Semiconductor structures and methods for making semiconductor structures include a split gate non-volatile memory (NVM) cell in an NVM region. A charge storage layer, a first conductive layer, and a capping layer are formed over the substrate, which are patterned to form a control gate stack in the NVM region of the substrate. A high-k dielectric layer, a metal layer, and a second conductive layer are formed over the substrate. The second conductive layer and the metal layer are patterned to form remaining portions of the second conductive layer and the metal layer over and adjacent to a first side of the control gate stack. The remaining portion of the second conductive layer is removed to form a select gate stack, which includes the remaining portion of the metal layer. A stressor layer is formed over the substrate.

1. Field
This disclosure relates generally to integrated non-volatile memory (NVM) and logic transistor manufacturing, and more specifically, to the making split gate NVM cells integrated with high-k, metal gate (HKMG) logic transistors.
2. Related Art
Non-volatile memories (NVMs) have become very significant in the semiconductor industry and thus the manner of making them has also become very significant. On the same integrated circuits are logic transistors, and in cases where the NVM is embedded in a much larger system, the logic transistor performance is the dominant concern. The cost of making the NVM is accordingly kept as low as possible while achieving the needed performance. Ways of achieving this normally includes using techniques that can be implemented with commonly available equipment and using materials that are well characterized. An effective approach for achieving the desired performance has been found to be the use of split gate NVM cells which utilize a select gate and a control gate over a continuous channel while using HKMG transistors for the logic transistors.
Accordingly there is a need to provide further improvement in achieving both low cost and high performance for split gate NVM cells in an integration with high-k, metal gate transistors.

Method of making a split gate non-volatile memory (NVM) cell and a logic transistor


A portable analytical grade mass spectrometer system contained in a single enclosure is disclosed for use in analyzing atmospheric, water, soil, drugs, explosives and other substances and includes a gas chromatograph and a mass analyzer assembly enclosed within a vacuum housing, a vacuum pump, and an on-board computer such that an operator, by means of an attached keyboard, can input data and information, and input a sample to be analyzed, and thereby operate the miniaturized mass spectrometer system.

The present invention relates generally to the determination of the chemical composition of unknown chemical compounds. More particularly, the present invention relates to apparatus for determining the chemical composition of environmental and non-environmental substances, such as hazardous and toxic chemicals, air and water contaminants.
In the area of environmental testing of the composition of the air, water, hazardous chemicals and other environmental as well as non-environmental samples, including the detection of drugs and explosives, it is often desirable and much of the time necessary to conduct the tests of such materials at the source or location of the materials. Since such materials are oftentimes found outside of controlled environments which are provided with sources of power, and since it is often important, for example, in the case of drugs and explosives, to quickly ascertain the presence of such substances in a rapid manner in the absence of readily available power sources, the need has arisen in the art for a compact, powerful and yet very sensitive instrument for testing as well as monitoring the chemical composition of such materials.
With many presently available systems, it takes days and often weeks to transport the samples to a central laboratory and obtain the results from the sophisticated routines necessary to analyze the chemical composition of certain substances. The present invention, on the other hand, both senses and analyzes such substances in minutes right on the site where the substance is found. In addition to providing advanced field testing and analysis, the present invention, which includes a novel gas chromatograph and mass spectrometer combination, provides a comprehensive real-time monitoring and on-site assessment capability for scientists, engineers, compliance specialists and others with environmental protection and public safety responsibilities.
The present system, then, combines in one portable compact package a fully integrated and totally self-contained system which couples a temperature programmed gas chromatograph with a high performance miniaturized mass spectrometer and on-board computer. The computer includes an operating system, as well as a mass spectra library and analysis software.


A smart glove includes a glove for housing and triggering electronic modules having a sensor; a triggering member for triggering the electronic modules; and a slide provided on the glove for partially or completely enclosing the electronic modules. The slide is made of a flexible material and comprises a base; two side walls extending from two side portions of the base; two channels extending starting from a first end of the base towards a second end of the base; a protrusion connected to the base from a connection end of the protrusion and extending between a channel; a lock end located at an end of the protrusion not connected to the base and extending from the protrusion perpendicularly or in an angled manner; a slot provided on an opposite end of the base without the lock end, comprising a hollow and extending from the base towards a roof.

Wearable sensors are used in factories, especially in production lines and logistics areas for saving time and energy, reducing error rates or increasing productivity etc.
The United States patent document no. US20170338610 A1, an application known in the state of the art, discloses a glove comprising an electronic module, a holder with clips for securing the electronic module and a button for activating the electronic module. However there is no element in this document for protecting the electronic module against the effects of impacts. Again in this document, the button is positioned next to the index finger and is not provided with any protection. Therefore, the button becomes active in cases of impacts or accidental situations. Again in this document, the pins on the electronic component of the glove are located below the electronic component. Therefore, the device wears out more quickly and its lifespan is reduced.
The United States patent document no. US20180146720A1, another application in the state of the art, discloses a glove comprising a button surrounded by a rigid protective element. However in this document the button is provided in the palm. In order to press the button, the fingers of the user make a flexion movement. During this movement, the flexor digitorum profundus, flexor superficialis and lumbricalis are activated and full range of motion is achieved. This exhausts the muscles. In addition, not every person is able to reach full range of motion easily. For such people, this type of movement overstrains the tendons and causes diseases such as carpal tunnel.
In these prior art documents, bonding techniques are used at the element which provides data transmission between the triggering button and the slide. There are conductive cables inside the bonded material. This element presents a rigid use in materials such as gloves having flexible use, and is uncomfortable. In addition, it is susceptible to cable breakage due to its inflexibility, and therefore the lifespan of the device decreases.
Industrial gloves vary according to their field of use. For example, in the area where aluminum parts are collected, there are specific knitting (weaving-density of the yarns) and coating properties for occupational health and safety standards. However, in other areas, for example spare parts in warehouses or production lines, gloves with different properties are used. In the said documents, uniform (single type) gloves are used.

TIM AKILLI KIYAFETLERI VE BILISIM TEKNOLOJISI ANONIM SIRKETI


In a tandem gas-shielded arc welding method, carbon dioxide is used as a shielding gas for a leading electrode formed by a solid wire, an argon-carbon dioxide gas mixture containing at least 60% by volume of argon gas is used as a shielding gas for a trailing electrode formed by a solid wire or a flux-cored wire, both the leading electrode and the trailing electrode have a reverse polarity, the leading electrode satisfies the relationships “5.00≦(I·V·10−8)/(Wf·πr2)≦10.00” and “(I2·10−3)/V≧4.50”, and the trailing electrode satisfies the relationships “4.00≦(I·V·10−8)/(Wf·πr2)≦7.00” and “(I2 10−3)/V≧8.00”.

1. Field of the Invention
The present invention relates to a two-electrode welding method in gas-shielded arc welding.
2. Description of the Related Art
Techniques for a gas-shielded arc welding method have been proposed in International Publication No. WO2008/016084, Japanese Unexamined Patent Application Publication No. 2004-188428, and Japanese Unexamined Patent Application Publication No. 2010-125496. For example, International Publication No. WO2008/016084 makes an assumption, in tandem gas metal arc (GMA) welding, that there is a different shielding gas composition suitable for each of a leading electrode and a trailing electrode. This is because the leading electrode has a function of increasing the depth of weld penetration into a base material, whereas the trailing electrode has a function of stopping the flow of metal with arc pressure to shape a molten pool, the metal being melted by an arc from the leading electrode and flowing backward from the molten pool. Under the assumption described above, International Publication No. WO2008/016084 proposes a technique in which, by supplying shielding gases of different compositions suitable for the leading electrode and the trailing electrode, it is possible to stabilize the droplet transfer and reduce the amount of spatter without sacrificing the depth of weld penetration.
Specifically, International Publication No. WO2008/016084 proposes a technique in which a leading-electrode shielding gas to be supplied to the leading electrode is a two-component gas mixture of argon gas and carbon dioxide or a three-component gas mixture of argon gas, carbon dioxide, and oxygen gas; a trailing-electrode shielding gas to be supplied to the trailing electrode is argon gas alone, a two-component gas mixture of argon gas and carbon dioxide, a two-component gas mixture of argon gas and oxygen gas, or a three-component gas mixture of argon gas, carbon dioxide, and oxygen gas; and the concentration of carbon dioxide in the trailing-electrode shielding gas is lower than that in the leading-electrode shielding gas.
Japanese Unexamined Patent Application Publication No. 2004-188428 proposes a welding wire and a welding method using the welding wire to solve the problem with related art in which, in welding using a shielding gas containing at least 50% by volume of carbon dioxide, it is very difficult to achieve spray transfer. That is, Japanese Unexamined Patent Application Publication No. 2004-188428 proposes a welding wire and a welding method using the welding wire with which, in carbon dioxide gas-shielded arc welding using a shielding gas mainly composed of carbon dioxide, droplet spray transfer can be achieved and it is possible not only to reduce the amount of spatter but also to obtain a good bead shape even when high-speed welding is performed. Note that the shielding gas mainly composed of carbon dioxide refers to a shielding gas that contains, for example, at least 50% by volume of carbon dioxide.
Specifically, Japanese Unexamined Patent Application Publication No. 2004-188428 proposes a technique in which a rare-earth element is added to a welding wire and the content of calcium (Ca) is specified to stabilize and concentrate an arcing point in a negative electrode; a straight polarity, which is opposite the normal polarity, is used (i.e., the welding wire is negatively charged) to reduce the amount of spatter even when a larger amount of carbon dioxide is contained in the shielding gas; and titanium (Ti), zirconium (Zr), and aluminum (Al), which are strong deoxidizing elements, are added to the welding wire to achieve more stabilized weldability.
Japanese Unexamined Patent Application Publication No. 2010-125496 proposes a technique in which, in a tandem gas-shielded arc welding method of consumable electrode type which uses two welding wires as electrodes, an active gas containing at least 40% by volume of carbon dioxide (CO2) is used as a shielding gas for the leading electrode, an inert gas containing a total of at least 99.5% by volume of one or two of argon (Ar) gas, helium (He) gas, and hydrogen (H2) gas is used as a shielding gas for the trailing electrode, and slag is removed by the trailing electrode before molten metal produced in the leading electrode is solidified.
In the technique proposed in International Publication No. WO2008/016084, a gas mixture mainly composed of inert gas, such as argon gas, is used as a shielding gas to reduce the amount of spatter. However, this technique has a problem in that the weld penetration is as shallow as that in a tandem method of related art. Also, the technique proposed in International Publication No. WO2008/016084 has a problem in that the cost of the shielding gas is high. Since the cost of inert gas, such as argon gas, is several times higher than that of carbon dioxide, it has been desired, in actual welding practice, to reduce the use of inert gas and to use a gas mainly composed of carbon dioxide as much as possible.
The technique proposed in Japanese Unexamined Patent Application Publication No. 2004-188428 has a problem in that the rare earth element added to the welding wire is expensive. Also, although the technique proposed in Japanese Unexamined Patent Application Publication No. 2004-188428 is limited to a straight polarity, a large amount of spatter is produced if, for example, welding is performed with a straight polarity by using an inexpensive solid wire.
As with the technique proposed in Japanese Unexamined Patent Application Publication No. 2004-188428, the technique proposed in Japanese Unexamined Patent Application Publication No. 2010-125496 has a problem in that the rare earth element added to the welding wire is expensive. Additionally, the technique proposed in Japanese Unexamined Patent Application Publication No. 2010-125496 has a problem in that it is not possible to perform tandem gas-shielded arc welding if an active gas containing 100% by volume of CO2 is used as a shielding gas for the leading electrode and, at the same time, an inexpensive solid wire is used as the leading electrode. As a preferred embodiment of this technique, Japanese Unexamined Patent Application Publication No. 2010-125496 proposes a technique in which the leading electrode and the trailing electrode are made to have a straight polarity and a reverse polarity, respectively. This causes two arcs to repel each other and affects the process in which a weld bead is shaped by the trailing electrode, which is the greatest benefit of tandem gas-shielded arc welding.
Generally, welding which uses carbon dioxide as a shielding gas for the leading electrode has been known for providing deep weld penetration. However, due to a very large amount of spatter, it has been unable to use carbon dioxide in tandem gas-shielded arc welding.
The present invention has been made in view of the problems described above. An object of the present invention is to provide a tandem gas-shielded arc welding method in which, even though 100% carbon dioxide is used for the leading electrode, it is possible to achieve lower cost, less spatter, and deeper weld penetration than those in tandem gas-shielded arc welding of related art which uses a shielding gas mainly composed of inert gas.


Disclosed is a protection cover allowing a handheld device to reversely discharge, which includes a bidirectional DC-DC converter and a charging/discharging controller arranged inside the protection cover so as to allow a first handheld device that is received in the protection cover to externally discharge electrical power thereof. The protection cover applies a removable external connection to electrically connect to a second handheld device so as to allow the first handheld device to reversely discharge, via the protection cover, to the second handheld device.

The progress of science and technology makes more and more handheld device (or handheld electronic device) carried by a user, such as a mobile phone, digital camera, digital camcorder, navigation device, and notebook computer that can are often carried by a user when the user is going out or taking a tour. These different handheld devices have dedicated rechargeable cells and rechargers for the purposes of recharging the rechargeable cells when they run out of power.
However, such handheld devices have individual and independent power supply system. Consequently, when one of these handheld devices runs out of power, it is not possible for the other handheld devices that may have extra powers to provide a supply of power to the run-out-of-power device.
Further, since it is often that more than two or three handheld devices (such as those listed above) are carried by a user going out of town or taking a trip, a number of chargers must also be carried, plus 110/220 volt power adaptors and various types of power plugs for use in different zones. It is apparently troublesome and inconvenient.
Thus, the present invention aims to provide a solution to overcome the above problems.

Protection cover allowing handheld device to reversely discharge


A device comprising a massfree energy receiver and means to convert massfree energy into ordinary electricity or mechanical work, including a pulsed plasma reactor driving an inertially damped drag motor.

Energy converters that are fed by local or environmental energy are usually explained by taking recourse to the notion that they convert zero point electromagnetic radiation (ZPE) to electric energy. The ZPE theories have gained a life of their own, as T. Kuhn has pointed out (in his "Black Body Theory and the Quantum"), after emerging from Planck's second theory, specifically from the term ½ hυ in the new formula for oscillator energy. In 1913, Einstein and Stern suggested that motional frequencies contributing to specific heat fell into two categories—those that were independent of temperature and those that were not (e.g. rotational energy), leading them to conclude that zero-point energy on the order of ½ hυ was most likely. In the second part of their paper, however, they provided a derivation of Planck's Law without taking recourse to discontinuity, by assuming that the value of the ZPE was simply hu. It is worth noting that Einstein had already in 1905 ("Erzeugung und Verwandlung des Lichtes betreffenden heuristichen Gesichtspunkt", Ann. d. Phys, 17, 132) framed the problem of discontinuity, even if only heuristically, as one of placing limits upon the infinite energy of the vacuum state raised by the Rayleigh-Jeans dispersion law. According to Einstein, the Rayleigh-Jeans law would result in an impossibility, the existence of infinite energy in the radiation field, and this was precisely incompatible with Planck's discovery—which suggested instead that at high frequencies the entropy of waves was replaced by the entropy of particles. Einstein, therefore, could only hope for a stochastic validation of Maxwell's equations at high frequencies "by supposing that electromagnetic theory yields correct time-average values of field quantities", and went on to assert that the vibration-energy of high frequency resonators is exclusively discontinuous (integral multiples of hυ).
Since then, ZPE theories have gone on a course independent from Planck's second theory. The more recent root of modern ZPE theories stems from the work of H. Casimir who, in 1948, apparently showed the existence of a force acting between two uncharged parallel plates. Fundamentally the Casimir effect is predicated upon the existence of a background field of energy permeating even the 'vacuum', which exerts a radiation pressure, homogeneously and from all directions in space, on every body bathed in it. Given two bodies or particles in proximity, they shield one another from this background radiation spectrum along the axis (i.e. the shortest distance) of their coupling, such that the radiation pressure on the facing surfaces of the two objects would be less than the radiation pressure experienced by all other surfaces and coming from all other directions in space. Under these conditions, the two objects are effectively pushed towards one another as if by an attractive force. As the distance separating the two objects diminishes, the force pushing them together increases until they collapse one onto the other. In this sense, the Casimir effect would be the macroscopic analogy of the microscopic van der Waals forces of attraction responsible for such dipole-dipole interactions as hydrogen bonding. However, it is worth noting that the van der Waals force is said to tend to establish its normal radius, or the optimal distance between dipoles, as the distance where the greatest attractive force is exerted, beyond which the van der Waals forces of nuclear and electronic repulsion overtake the attraction force.
Subsequently, another Dutch physicist, M. Sparnaay, demonstrated that the Casimir force did not arise from thermal radiation and, in 1958, went on to attribute this force to the differential of radiation pressure between the ZPE radiation from the vacuum state surrounding the plates and the ZPE radiation present in the space between them. Sparnaay's proposal is that a classical, nonquantal, isotropic and ubiquitous electromagnetic zero-point energy exists in the vacuum, and even at a temperature of absolute zero. It is further assumed that since the ZPE radiation is invariant with respect to the Lorentz transformations, it obeys the rule that the intensity of its radiation is proportional to the cube of the frequency, resulting in an infinite energy density for its radiation spectrum.
What appeared to be the virtue of this reformulated theory was the notion that the vacuum no longer figured as pure space empty of energy, but rather as a space exposed to constantly fluctuating 'fields of electromagnetic energy'.
Puthoff has utilized the isomorphism between van der Waals and Casimir forces to put forth the zero-point (ZP) energy theory of gravity, based on the interpretation that the virtual electromagnetic ZP field spectrum predicted by quantum electrodynamics (QED) is functionally equivalent to an actual vacuum state defined as a background of classical or Maxwellian electromagnetic radiation of random phases, and thus can be treated by stochastic electrodynamics (SED). Whereas in QED, the quanta are taken as virtual entities and the infinite energy of the vacuum has no physical reality, for SED, the ZPE spectrum results from the distortion of a real physical field and does not require particle creation. Gravity then, could be seen as but the macroscopic manifestation of the Casimir force.
We do not dispute the fact that even in space absent matter there is radiant energy present which is not of a thermal nature. But we claim that this energy is not electromagnetic, nor is its energy spectrum infinite. That this is so stems not just from our opinion that it is high time that Einstein's heuristic hypothesis should be taken as literally factual—in the dual sense that all electromagnetic energy is photon energy and all photons are local productions, but above all from the fact that it is apparent, from the experiments of Wang and his colleagues (Wang, Li, Kuzmich, A & Dogariu, A. "Gain-assisted superluminal light propagation", Nature 406; #6793; 277), that the photon stimulus can propagate at supraluminal speeds and lies therefore well outside of any scope of electromagnetic theory, be this Maxwell's classical approach taken up by ZPE theories, or Einstein's special relativistic phenomenology of Maxwell's theory. The fact is that if the light stimulus can propagate at speeds greater than those of light, then what propagates is not light at all, and thus not energy configured electromagnetically. Light is solely a local production of photons in response to the propagation of a stimulus that itself is not electromagnetic.
It is critical to understand that the implication from this that—aside from local electromagnetic radiation and from thermal radiation associated with the motions of molecules (thermo-mechanical energy), there is at least another form of energy radiation which is everywhere present, even in space absent matter. Undoubtedly, it is that energy that prevents any attainment of absolute zero, for any possible local outpumping of heat is matched by an immediate local conversion of some of this energy into a minimum thermal radiation required by the manifolds of Space and Time. And undoubtedly also this radiation is ubiquitous and not subject to relativistic transformations (i.e. Lorentz invariant). What it is not, is electromagnetic radiation consisting of randomistic phases of transverse waves.
To understand this properly, one must summarize the differences from existing ZPE theories—and all these differences come down to the fact that this energy which is neither electromagnetic nor thermal per se (and is certainly not merely thermo-mechanical), has nevertheless identifiable characteristics both distributed across subtypes or variants and as well common to all of them.
Essentially the first subtype or variant consists of longitudinal massfree waves that deploy electric energy. They could well be called Tesla waves, since Tesla-type transformers can indeed be shown experimentally to radiate massfree electric energy, in the form of longitudinal magnetic and electric waves having properties not reduceable to photon energy or to 'electromagnetic waves', and having speeds of displacement that can be much greater than the limit c for all strictly electromagnetic interactions.
One may well denote the second subtype by the designation of massfree thermal radiation, since it contributes to temperature changes—and, as obviously indicated by the impossibility of reaching an absolute zero of temperature, this contribution occurs independently of the presence of matter, or mass-energy, in Space. In other words, not all thermal radiation can be reduced to vibration, rotation and translation (drift motion) of molecules, i.e. to thermomechanical energy, because the properties of pressure and volume that determine temperature and affect matter, appear indeed to a great extent to be independent from matter, a fact which itself is responsible for the observed catastrophic and unexpected phase changes of matter and has required to this day the insufficient explanation offered semi-empirically by the Van der Waals Force Law.
Finally the third subtype may be designated latent massfree energy radiation—since it deploys neither charge, nor thermal or baroscopic effects, and yet it is responsible for 'true latent heat' or for the 'intrinsic potential energy' of a molecule. It is also responsible for the kinetoregenerative phenomenon whereby an electroscope performs a variable charge-mediated work against the local gravitational field.
The common characteristic of all three subtypes of massfree energy radiation is that they share the same nonclassical fine structure, written as follows for any energy unit, where c is any speed of light wave function, and the wavelength λ and wave function W are interconnected as a function of the physical quality of the energy field under consideration:E=λcW
In the instance of longitudinal electric radiation, this takes on the directly quantizable form:E=(λqc)Wv=peWv=(h/λx)Wv=∫=qVwhere Wv is the voltage-equivalent wave function corresponding to V, pe constitutes the linear momentum corresponding to the conventional q or e, h is the Planck constant, λx the Duane-Hunt constant expressed as a wavelength, λq is a wavelength constant; and the sign =∫=signifies exact equality between an expression in the conventional dimensions of length, mass and time, and an expression in length and time dimensions alone.
In the instance of massfree thermal radiation (contributing to temperature changes), the transformation obeys Boltzmann's rule (k is now Boltzmann's constant and T is Kelvin-scale temperature):E=λn1cWn1=λn1(λVζp)(λαζn1)=∫=kTand in the third instance—of latent massfree radiation, the transformation obeys the rule:E=λn1cWn1=λn1(λn1ζn1)(λn1fn1)=λn13ζn1fn1where ζ and f are frequency functions, f being a specific gravitational frequency term, and fn1 being defined as equal to (λn1)−0.5 meter0.5sec−1. ζn1 has the value of c/λn1.
If the electric variant of massfree radiation has a direct quantum equivalence, via the Duane-Hunt Law, none of the three primary aether energy variants possess either the classic form of electromagnetic energy which requires square superimposition of speed of light wave functions c, as c2, or the quantum form of energy, requiring E=hυ. The critical first step in the right direction may well be attributed to Dr. W. Reich, as it regards the fact that massfree energy couples two unequal wave functions, only one of which is electromagnetic and abides by the limit c. We then unravelled the threefold structure described above, and further showed that, in the case of longitudinal electric waves, the postulated equivalence (q=λqc) is merely phenomenological, as these waves are not restricted by the function c in their conveying of electric charge across space. It can further be demonstrated that all blackbody photons are bound by an upper frequency limit (64*1014 Hz), above which only ionizing photons are produced, and that all blackbody photons arise precisely from the interaction of massfree electric radiation with molecules of matter (including light leptons), whereby the energy of that radiation is locally converted into photon or electromagnetic radiation. In other words, all nonionizing electromagnetic energy appears to be secondary energy that results locally from the interaction of matter with massfree electric energy. It cannot therefore consist of the primary energy that is present in the vacuum, an energy that is neither virtual nor electromagnetic, but actual and concrete in its electric, thermal and antigravitic manifestations. Lastly, gravitational energy, being either the potential or the kinetic energy responsible for the force of attraction between units of matter, is a manifestation that also requires, much as electromagnetic radiation does, coupling of massfree energy to matter or to mass-energy.
The Tesla coil is a generator of a massfree electric energy flux that it transmits both by conduction through the atmosphere and by conduction through the ground. Tesla thought it did just that, but it has been since regarded instead (because of Maxwell, Hertz and Marconi) as a transmitter of electromagnetic energy. The transmitter operates by a consumption of massbound electric power in the primary, and by induction it generates in the coupled secondary two electric fluxes, one massbound in the coil conductor, and the other massfree in the body of the solenoid. Tesla also proposed and demonstrated a receiver for the massfree energy flux in the form of a second Tesla coil resonant with the first. The receiver coil must be identical and tuned to the transmitter coil; the capacitance of the antenna plate must match that of the transmitter plate; both transmitter and receiver coils must be grounded; and the receiver coil input and output must be unipolar, as if the coil were wired in series.
The generators of massfree energy with which we are concerned provide current pulses associated with a damped wave (DW) oscillation of much higher frequency than the pulse repetition frequency. A particular problem in recovering the massfree energy content of such pulses is provided by the damped wave oscillations. Although in our U.S. Pat. No. 5,416,391 we describe arrangements incorporating split phase motors to recover such energy, their efficiency is a great deal less than what should theoretically be attainable. Other workers such as Tesla and Reich, have encountered the same problem to an even greater degree.
In XIXth century motor engineering terminology, dynamos capable of producing direct current by continuous homopolar induction were known as 'unipolar' generators. The term unipolar induction appears to have originated with W. Weber, to designate homopolar machines where the conductor moves continuously to cut the magnetic lines of one kind of magnetic pole only, and thus require sliding contacts to collect the generated current. Faraday's rotating copper disc apparatus was, in this sense, a homopolar generator when the disc was driven manually, or a homopolar motor when the current was provided to it. Where the rotating conductor continuously cuts the magnetic field of alternatingly opposite magnetic poles, the operation of a machine, whether a generator or a motor, is said to be heteropolar. Unipolar machines went on to have a life of their own in the form of low voltage and high current DC generators—from Faraday, through Plucker, Varley, Siemens, Ferraris, Hummel, to Lord Kelvin, Pancinoti, Tesla and others—almost exclusively in the form of disc dynamos, but some having wound rotors. In Mordey's alternator, and in so-called 'inductor alternators', however, homopolar generators were employed to obtain alternating currents, with the use of rotors wound back and forth across the field. Use of smooth, unwound rotors in AC induction motors (as opposed to AC synchronous motors, such as hysteresis motors) was a later development than homopolar dynamos. By 1888, Tesla and Ferraris amongst still others, had independently produced rotating magnetic fields in a motor, by employing two separate alternate currents with the same frequency but different phase. Single phase alternate current motors were developed later, and split-phase motors were developed last. Ferraris (Ferraris, G (1888) "Rotazioni elettrodynamiche", Turin Acad, March issue.) proposed the elementary theory of the 2-phase motor, where the current induced in the rotor is proportional to the slip (the difference between the angular velocity of the magnetic field and that of the rotating cylinder), and the power of the motor is proportional to both the slip and the velocity of the rotor.
If an iron rotor is placed within the rotating magnetic field of a 2-phase stator, it will be set in rotation, but not synchronously, given that it is always attracted to the moving magnetic poles with a lag. But if an aluminum or copper rotor is used instead, it becomes 'dragged' around by the rotating stator field because of the eddy currents induced in it. If the aluminum or copper rotor were to rotate synchronously with the stator magnetic field, there would be no induced eddy currents and thus no motor action would result. The motor action depends, in this instance, upon the presence of asynchronous slip, since the function of the latter is to sustain the induction of those currents in the rotor that are responsible for the motor action of the dragged rotor. This then is the origin of the term 'AC drag motors'. Once the drag rotor evolved from a cylinder to a hollow cup, they earned the epithet of 'drag-cup motors'. Later, already in the XXth century, the cups were fitted over a central stator member, and the sleeve rotor 2 phase servomotor was born.
Tesla knew that impulse currents as well as CW sinusoidal currents could be used to drive AC motors. Regarding his invention of an hysteresis motor ('magnetic lag motor', as he called it), he stated: ". . . pulsatory as well as an alternating current might be used to drive the[se] motors . . . " (Martin, T C (1894) "The inventions, researches and writings of Nikola Tesla", Chapter XII, p. 68). In his search for efficient utilization of the high frequency DW impulse currents of his induction coils, Tesla began by employing an AC disc induction motor as shown in FIG. 17 of his famous 1892 address (Tesla, N (1892) "Experiments with alternate currents of high potential and high frequency", in "Nikola Tesla Lectures", 1956, Beograd, pp. L-70–71). This consisted of a copper or aluminum disc mounted vertically along the longitudinal axis of an iron core on which was wound a single motor coil which was series wired to the distal terminal of an induction coil at one end, and to a large suspended and insulated metal plate at the other. What was new about this was the implementation of an AC disc induction motor drive, where the exciting current traveled directly through the winding with just a unipolar connection to the coil secondary (under certain conditions, even the series connection to the plate could be removed, or replaced with a direct connection to the experimenter's body): "What I wish to show you is that this motor rotates with one single connection between it and the generator" (Tesla, N. (1892), op. cit., L-70, Tesla's emphasis). Indeed, he had just made a critical discovery that, unlike in the case of massbound charge where current flow requires depolarization of a bipolar tension, massfree charge engages current flow unipolarly as a mere matter of proper phase synchronization.
Tesla thought that his motor was particularly adequate to respond to windings that had 'high-self-induction', such as a single coil wound on an iron core. The basis of this self-induction is the magnetic reaction of a circuit, or an element of a circuit—an inductor—whereby it chokes, dims or dampens the amplitude of electric waves and retards their phase.
For the motor to respond to still higher frequencies, one needed to wind over the primary motor winding a partial overlap secondary, closed through a capacitor, since "it is not at all easy to obtain rotation with excessive frequencies, as the secondary cuts off almost completely the lines of the primary" (Idem, L-71.).
Tesla stated that "an additional feature of interest about this motor" was that one could run it with a single connection to the earth ground, although in fact one end of the motor primary coil had to remain connected to the large, suspended metal plate, placed so as to receive or be bathed by "an alternating electrostatic field", while the other end was taken to ground. Thus Tesla had an ordinary induction coil that transmitted this "alternating electrostatic field", an untuned Tesla antenna receiving this "field", and a receiver circuit comprising his iron-core wound motor primary, a closely coupled, capacitatively closed secondary, and the coupled nonferromagnetic disc rotor. Eventually, in his power transmission system, he would replace this transmitter with a Tesla coil, and place an identical receiving coil at the receiving end, to tune both systems and bring them into resonance. But his motor remained undeveloped, and so did the entire receiver system.
Tesla returned to this subject a year later: "on a former occasion I have described a simple form of motor comprising a single exciting coil, an iron core and disc" (Tesla, N (1893) "On light and other high frequency phenomena", in "Nikola Tesla Lectures", 1956, Beograd, pp. L-130, and L-131 with respect to FIG. 16-II). He describes how he developed a variety of ways to operate such AC motors unipolarly from an induction transformer, and as well other arrangements for "operating a certain class of alternating motors founded on the action of currents of differing phase". Here, the connection to the induction transformer is altered so that the motor primary is driven from the coarse secondary of a transformer, whose finer primary is coupled, at one end, directly and with a single wire to the Tesla secondary, and at the other left unconnected. On this occasion, Tesla mentions that such a motor has been called a 'magnetic lag motor', but that this expression (which, incidentally, he had himself applied to his own invention of magnetic hysteresis motors) is objected to by "those who attribute the rotation of the disc to eddy currents when the core is finally subdivided" (Tesla, N (1893), op. cit., p. L-130).
In none of the other motor solutions, 2-phase or split-phase, that he suggests as unipolar couplings to the secondary of an induction coil, does the nonferromagnetic disc rotor motor again figure. But he returns to it a page later, and indirectly so, by first addressing the disadvantages of ferromagnetic rotors: "Very high frequencies are of course not practicable with motors on account of the necessity of employing iron cores. But one may use sudden discharges of low frequency and thus obtain certain advantages of high-frequency currents without rendering the iron core entirely incapable of following the changes and without entailing a very great expenditure of energy in the core. I have found it quite practicable to operate, with such low frequency disruptive discharges of condensers, alternating-current motors."
In other words—whereas his experiments with constant wave (CW) alternating currents, and as well with high-voltage DW impulses from induction coils, indicated the existence of an upper frequency limit to iron core motor performance, one might employ instead high-current, DW impulses—of high DW frequencies but low impulse rates—to move these motors quite efficiently. Then he adds "A certain class of [AC] motors which I advanced a few years ago, that contain closed secondary circuits, will rotate quite vigorously when the discharges are directed through the exciting coils [emphasis added]. One reason that such a motor operates so well with these discharges is that the difference of phase between the primary and secondary currents is 90 degrees, which is generally not the case with harmonically rising and failing currents of low frequency. It might not be without interest to show an experiment with a simple motor of this kind, inasmuch as it is commonly thought that disruptive discharges are unsuitable for such purposes."
What he proposes next forms the basis of modern residential and industrial AC electric power meters, the AC copper disc motor whose rotor turns on the window of these meters, propelled forward by the supply frequency. But instead of employing any such CW input, Tesla uses the disruptive discharges of condensers, incipiently operating as current rectifiers. With the proper conditions, e.g. correct voltage from the generator, adequate current from the capacitor, optimum capacitance for the firing rate, and tuned spark-gap, to mention a few, Tesla found that the nonferromagnetic disc rotor turned but with considerable effort. But this hardly compared to the results obtained with a high-frequency CW alternator, which could drive the disc "with a much smaller effort". In summary then, Tesla went as far as being the first to devise a motor driven by Tesla waves, that employed a nonferromagnetic rotor, and whose arrangement encompassed both transmitter and receiver circuits. For this purpose, he employed a single phase method in which the signal is fed unipolarly to the winding, placed in series with a plate capacitance.
Tesla also later proposed driving a similar single-phase nonferromagnetic disc motor from bipolar capacitative discharges through an atmospheric spark-gap now placed in parallel with the main motor winding, and again simulating a split-phase by a closely wound secondary that was closed by a capacitance.
As Tesla admits, the results of all his AC eddy current motor solutions were meagre and limited by current and frequency problems. Likewise, the two phase arrangements proposed by Reich for his OR motor, involving a superimposition of the damped waves of a first phase on a fixed continuous wave second phase, require an external power source and a pulse amplifier circuit, and failed to meet Reich's own desiderata.
We have previously proposed the use of squirrel cage motors with capacitative splitting of phase to convert the damped wave (DW) output of plasma pulsers, but once a squirrel cage (SC) is introduced, the dampening effect which the nonferromagnetic copper cage exerts in being dragged by the revolving stator field is counteracted by the ferromagnetic cylinder of laminated iron, in which the copper cage is embedded, working to diminish the slip and bring the rotor to near synchronism. This is, in all likelihood, what limits SC motors to responding to the DC component of the DW impulse, and thus be limited to respond to fluxes of massbound charges. Historically, as we shall see, the obvious advantage of the SC servomotors lay in the fact that, in particular for 2-phase applications, they were far more efficient at performing work without evolution of heat. Indeed, if the eddy currents in the nonferromagnetic rotor are permitted to circulate in nonordered form, the rotor material and stator will heat up rapidly and consume much power in that heating. This is in fact considered to be a weakness of AC nonferromagnetic-rotor induction motors.


An MR device for MR imaging includes an RF coil system. In order to enable switching to and fro between different applications in such an MR device without having to move the patient so as to position a new RF coil system, it is proposed to provide the RF coil system for the transmission and/or reception of RF signals with at least two RF coil arrays which are integrated in one coil former and have been optimized for different applications, each RF coil array comprising at least two RF coils which are decoupled from one another.

The invention relates to a magnetic resonance (MR) device for MR imaging as well as to an RF coil system for such an MR device.
MR devices of this kind are generally known and described in numerous documents, for example, in U.S. Pat. No. 6,377,045 which discloses a magnetic resonance device for carrying out the SENSE method by means of an RF coil array. The optimization of RF coil arrays is of major importance for MR imaging. For given clinical protocols a specific optimization of the image quality can be achieved by parameter variation of the coil number, the coil configuration and the arrangement of the coils. The object basically consists of obtaining a maximum signal-to-noise ratio (SNR). A high SNR in deeper layers is achieved by means of RF coils having a given minimum size. However, the maximum number of RF coils in relation to the given size of the object to be examined, for example, a patient, is thus limited. When using parallel imaging methods, such as SENSE or SMASH the number of RF coils is increased so as to obtain a high reduction factor for a corresponding temporal resolution.
It can be stated in principle that the design criteria for RF coils differ significantly in dependence on the relevant application and the imaging method. For example, when the SENSE imaging method is used, a low error propagation rate should be achieved in combination with a high reduction factor, whereas maximization of the SNR is most important when synergy coils are used. It follows therefrom that an RF coil array which has been optimized for the SENSE method also deviates geometrically from a synergy coil array in respect of the number, the size and the position of the RF coils.
For clinical applications it is desirable that switching over between and selection of different applications and imaging methods can take place at will without it being necessary to move the patient in order to fit a new RF coil array. Therefore, it is an object of the invention to provide an MR device as well as an RF coil system for such an MR device which enable such selection and switching.

MR device provided with differently optimized RF coil arrays


A semiconductor device includes a logic structure including a logic circuit disposed in a circuit region and a lower insulation covering the logic circuit, a memory structure on the logic structure, a stress relaxation structure interposed between the logic structure and the memory structure in the circuit region, and a connection structure electrically connecting the memory structure to the logic circuit along a conductive path that extends through a connection region of the device beside the circuit region.

The inventive concepts relate to semiconductor devices and methods of manufacturing the same. More particularly, the inventive concepts relate to non-volatile semiconductor memory devices and methods of manufacturing the same.
The integration density of semiconductor memory devices may be proportional to the cost of the semiconductor memory devices. A conventional two-dimensional (2D) memory device includes a planar array of unit memory cells formed of fine patterns of certain elements and features. The integration density of such a conventional two-dimensional (2D) memory device mainly corresponds to the area occupied by a unit memory cell of the device. Thus, the degree to which the integration density of a 2D memory device can be increased greatly depends on advances in techniques of forming fine patterns. However, apparatuses for forming fine patterns are very expensive to begin with and the cost of these apparatuses will only increase along with the fineness of the patterns that they are able to produce. Therefore, manufacturing costs may impose limits on the extent to which the integration densities of 2D memory devices are increased. In light of this, three-dimensional (3D) semiconductor devices have been developed. Three-dimensional (3D) semiconductor memory devices provide high integration densities and excellent performance while being relative inexpensive to manufacture per unit memory cell.


A surgical implant system includes an implant and a fixation member for securing the implant to tissue. The implant and the fixation member together comprise a single monolithic structure. The implant includes an insertion instrument. The implant, the fixation member, and the insertion instrument together comprise a single monolithic structure and are constructed from a single material. The implant is monolithically connected to the fixation member at a first frangible connection and is monolithically connected to the insertion instrument at a second frangible connection. Each of the frangible connections can be broken when force is applied.

The present inventions relate, in general, to surgical implant systems and methods of implanting same. More particularly, the present inventions relate to surgical implant systems including monolithic structures having an implant, a fixation member, and/or an instrument that are frangibly connected for separation during a surgical procedure.
Surgical implants often include several components. The implant itself may be comprised of different pieces, and is often secured to adjacent tissue by one or more additional fixation elements, such as screws or anchors. In addition, one or more instruments are typically needed during a surgical procedure to grasp and guide the implant and to place the fixation element(s) to secure the implant. The many components needed during one procedure can pose challenges for organization in the operating room, sterilization to prevent infection, and accuracy and efficiency in properly handling and placing the implant and fixation element(s) during a procedure. For instance, dropping or mishandling smaller screws can be a challenge during a procedure. This increases manufacturing costs as well as inventory of implants and instrumentation.
There is a need in the art for a surgical implant system that overcomes these drawbacks by simplifying surgical procedures and by making such procedures more efficient.

Fusion cage with integrated fixation and insertion features


In a power supply system for a passive safety device, a step-up circuit steps up an input voltage based on a supply voltage from a battery to obtain a predetermined output voltage. An input voltage detecting circuit detects the input voltage. An output voltage changing circuit changes the output voltage based on a detection signal from the input voltage detecting circuit. Thus, the control load on the step-up circuit is reduced and increase in the size and rating of the step-up circuit is suppressed.

A conventional power supply system 100 for a vehicle (for instance, JP 10-129402 A2 and JP 08-310337 A2), as illustrated in FIG. 7, comprises a battery 101, a first power supply circuit 102, a second power supply circuit 103, a firing circuit 104, a satellite sensor communication circuit 105, a microcomputer 106, a crash sensor 107, a nonvolatile memory 108 and a backup capacitor 109.
The first power supply circuit 102 steps up or boosts an input voltage vin based on the supply voltage of the battery 101 to provide a predetermined high output voltage Vout (24V). The output voltage Vout is supplied to the firing circuit 104, satellite sensor communication circuit 105 and second power supply circuit 103. The backup capacitor 109 is charged with the output voltage Vout. The second power supply circuit 103 steps down the output voltage Vout to provide a predetermined low output voltage (5V). The input voltage at which the second power supply circuit 103 can stably operate as a 5V regulator is 5.5V. The output voltage of the second power supply circuit 103 is used as power supply voltage for the microcomputer 106, crash sensor 107 and nonvolatile memory 108.
Recently, the power supply system 100 is provided with occupant protecting functions against rear seat side impact and roll over as well as against front impact and front seat side impact. For this reason, the numbers of installed satellite sensors and airbags tend to increase. The processing speed of the microcomputer 106 is increased. For high performance of the power supply system 100, more than one microcomputer 106 may be installed. In this instance, the current consumption in ECUs (Electronic Control Units) is increased. This will result in the increased size and rating of the first power supply circuit 102.
The load on the first power supply circuit 102, that is, the voltage step-up control load is increased with increase in the difference between the input voltage Vin and the output voltage Vout. That is, the lower the supply voltage from the battery 101 is, the higher the voltage step-up control load is. To stably ensure the desired output voltage Vout according to the magnitude of the difference between the input voltage Vin and the output voltage Vout, the size and rating of the first power supply circuit 102 must be increased.
In consideration of the foregoing, another passive safety device is proposed in, for instance JP 09-290704A2 (U.S. Pat. No. 5,995,891), to reduce the current born by the first power supply circuit 102. This device is shown in FIG. 8.
This power supply system 100 is different from that shown in FIG. 7 in that an input voltage detecting circuit 110, a switching element 111 and reverse current blocking diodes 112, 113 are additionally installed. In the input voltage detecting circuit 110, the input voltage Vin is compared with a predetermined threshold value (5.5V). When the input voltage Vin is 5.5V or higher, the switching element 111 is opened (turned off) by a signal from the input voltage detecting circuit 110. For this reason, the first power supply circuit 102 and the second power supply circuit 103 are disconnected from each other. When the input voltage Vin is lower than 5.5V, the switching element 111 is closed by the signal from the input voltage detecting circuit 110. For this reason, the first power supply circuit 102 and the second power supply circuit 103 are connected to each other.
In this power supply system 100, the current for the downstream side of the second power supply circuit 103 need not be ensured at the first power supply circuit 102 when the input voltage Vin is 5.5V or higher. It need not be ensured when the supply voltage from the battery 101 is 6.5V or higher with the voltage drop (1V) at a reverse current blocking diode 112 taken into account. For this reason, the voltage step-up control load on the first power supply circuit 102 can be reduced. Therefore, increase in the size and rating of the first power supply circuit 102 can be suppressed.
However, when the supply voltage from the battery 101 is lower than 6.5V, it is difficult to ensure the operation of the second power supply circuit 103. It is assumed here that the second power supply circuit 103 is operated with the supply voltage from the battery 101 being up to 6V. As described above, the input voltage at which the second power supply circuit 103 can stably operate as a 5V regulator is 5.5V For this reason, in the power supply system 100, the second power supply circuit 103 cannot be operated, when the supply voltage from the battery 101 is within the range between 6V (inclusive) and 6.5V (exclusive) with voltage drop (1V) at the reverse current blocking diode 113.


A method for creating and managing customized print media through an enhanced content management process is disclosed. A print media customer, which may be an individual or organization, is profiled to determine content preferences. Profiling may be based on face-to-face or electronic surveys, Internet usage patterns, buying patterns, or other criteria. Content associated with the preferences is obtained and analyzed. Content affinities, or relationships between the content and other content in a content network, are determined, and may influence the print media produced. A history of the content is maintained, to ensure content is not duplicated. Both substantive and non-substantive content, such as advertising content, is used. Both the content and layout of the print media can be customized.

This invention relates to the publication of customized and personalized newspapers, newsletters, magazines, periodicals, journals, catalogs, books and other printed media.
The current state of the art in the print publishing world is primarily to "broadcast" identical issues of a publication to all customers. Although electronic media, such as Internet sites, allow customization of information for various customer segments and/or individuals, print media has generally remained un-customized. Rather, periodicals, books and other print media are often targeted to a particular market segments in a coarse-grained manner. Prior art in print media customization relates to simple regional customization in newspapers and to some extent periodicals. Minor customization of books is also not unknown. However, the ability to mass customize print media such as newspapers, books, magazines, etc. has not been a reality.
Unfortunately, this coarse-grained approach to the delivery of printed material puts real limits on the value of the print media to its customers, and limits the ability to adequately contextualize print advertising for the consumers of the print media. A by-product of this lack of contextualization is the reduction in the potential value of print media advertising.
Electronic media allows for better customization, and this will become increasingly effective. However, print media will continue to have significant advantages for some time to come. For example, print media is often more convenient than electronic media. It is highly portable, always available, etc. Also, the resolution of print is better than that of display screens, which reduces reading fatigue.
The historic lack of customization of print media is primarily due to the processes and technologies involved. It has simply generally been prohibitively expensive to customize print runs of a particular magazine or book for specific organizations and individuals. This is partly due to the economics of content assembly, layout and printing. It is also partly due to limitations of sufficient, high quality and modular content, and the ability to easily aggregate and understand customer preferences for content, and effective organization and display of content.
However, recent advances in software and printing technologies have enabled a much more economic and extensive customization of print media. For example, leveraging digital press technology, magazine-quality printers are now much less expensive—enabling more cost-effective very short print runs. This has made the "bottleneck" to highly customized and personalized print media to be one of information management rather than that of the mechanics of volume printing. Fortunately advanced information processes will increasingly become available to make true customization of print media feasible. In particular, the Internet, as a mass information management and gathering environment enables the intelligent surveying, aggregation and analysis of print media customers to provide sufficient information to customize print media. In addition, integration of print media and Internet sites can be effected—enabling cross-referencing of content, etc.
The customization of print media provides part of the solution to the problem of "information overload", in that irrelevant information is less likely to be pushed on to readers. The more contextualized and relevant the information delivered to the individual consumer, the higher the value.
This invention provides a comprehensive method for effectively creating and managing customized print media through an enhanced content management process.

Method and system for customized print publication and management


According to the invention, a packaged integrated circuit includes a lid attached to a base to enclose a cavity, an integrated circuit chip or chips being attached to each of the lid and base within the cavity. Preferably, the chip or chips that generate the most heat during operation of the packaged integrated circuit are attached to the lid and the lid is made of a material having good thermal conductivity such as aluminum nitride. The chips attached to the base generate relatively little heat and so do not require a heat sink to be included in the base. The packaged integrated circuit is formed in a cavity-up configuration, thereby enabling connection pins or solder balls to be formed over the entire exterior surface of the base, increasing interconnection density. Additionally, attachment of chips to both the lid and the base allows an increased number of electronic functions to be included in one packaged integrated circuit. Further, the chip or chips attached to the lid can be tested before being committed to the base, thereby enabling defective chips to be discarded without having to discard the relatively expensive base.

1. Field of the Invention
This invention relates to integrated circuits and, in particular, to packaged integrated circuits in which a lid is attached to a base to enclose a semiconductor die.
2. Related Art
Integrated circuit chips (semiconductor dice on which electrically conductive material is formed) can be packaged in a variety of ways, e.g., encapsulated in plastic, enclosed in ceramic, or enclosed in a metal can, to form packaged integrated circuits. Packaged integrated circuits can be mounted on, for instance, a printed circuit board so that the integrated circuit chip within the package is connected to electrically conductive material outside the package. In through-hole mounting, e.g., dual-in-line packages (DIPs) and pin grid arrays (PGAs), electrically conductive pins that extend outside the package are inserted into holes formed in a mounting board, the holes being coated with electrically conductive material. In surface mounting, e.g., plastic leaded chip carriers (PLCCs) and quad flat packs (QFPs), electrically conductive leads extend outside the package and are attached to electrically conductive material formed on a surface of the mounting board.
FIG. 1A is a cross-sectional view of a prior art cavity-down ceramic pin grid array (PGA) 100. Integrated circuit chip 104 is attached to surface 102a of ceramic base 102 within a cavity formed in base 102. Heat sink 106 is formed in base 102 in proximity to chip 104 such that heat sink 106 is exposed beyond surface 102d of base 102 to the exterior of cavity-down PGA 100. Bond wires 103 are used to make electrical connection between bond pads (not shown) on chip 104 and bond pads (not shown) on surface 102c of base 102. Lid 105 is attached with adhesive 107 to surface 102b of base 102 to seal chip 104 in the cavity. Electrically conductive pins 101 extend from surface 102b of base 102. Pins 101 are electrically connected to the bond pads on surface 102c by electrically conductive vias and traces (not shown) formed in base 102. Cavity-down PGA 100 is mounted on a mounting board by positioning pins 101 in corresponding holes formed in the mounting board, the holes being coated with electrically conductive material.
FIG. 1B is a plan view along direction 1B--1B (FIG. 1A) of cavity-down PGA 100 illustrating surface 102b from which pins 101 extend. For clarity, lid 105, bond wires 103 and heat sink 106 are not shown, and only some of pins 101 are shown. As is evident from FIG. 1B, a large portion of surface 102b from which pins 101 could otherwise extend, is unavailable for that purpose. For instance, pins 101 cannot be located near inner peripheral edge 112a of surface 102b since lid 105 (FIG. 1A) must be attached to surface 102b near edge 112a. Further, a relatively large area (circumscribed by edge 112a in FIG. 1B) must be eliminated from surface 102b in order to allow space for chip 104 and the bond pads on surface 102c.
Given the above constraints, the area defined by outer peripheral edge 112b of surface 102b (the "footprint" of cavity-down PGA 100) must be made large enough so that surface 102b is large enough to accommodate the desired number of pins 101.
FIG. 2 is a cross-sectional view of a prior art cavity-up ceramic PGA 200. Cavity-up PGA 200 is similar to cavity-down PGA 100 and similar elements are designated with the same numerals in FIGS. 1A, 1B and 2. In cavity-up PGA 200, pins 101 extend from surface 102d of base 102, rather than surface 102b of base 102 as in cavity-down PGA 100. In cavity-up PGA 200, the above-noted limitations on usage of surface 102b for placement of pins 101 are not present, since pins 101 do not extend from surface 102b. However, the presence of heat sink 106 still prevents complete usage of surface 102d for pins 101 and the footprint of cavity-up PGA 200 is, like cavity-down PGA 100, undesirably large. While elimination of heat sink 106 would provide more area on surface 102d for pins 101, thereby enabling the footprint of cavity-up PGA 200 to be made smaller, the absence of heat sink 106 would prevent effective removal of heat from cavity-up PGA 200 during operation.
Additionally, in conventional PGAs (either cavity-up or cavity-down), an integrated circuit chip is attached only to a surface, e.g., surface 102a, of the package base, e.g., base 102. The package lid is generally not sufficiently robust to support an integrated circuit chip. Also, the package cavity is not large enough to accommodate a chip attached to the lid and a chip attached to the base.
In a packaged integrated circuit, each integrated circuit chip must be tested for proper functionality after being attached and electrically connected to the package leads. In conventional PGAs, a chip or chips are attached and electrically connected to a package base which also includes a heat sink and the package pins (e.g., FIGS. 1A and 1B). Thus, the chip or chips are tested only after being committed to the relatively expensive package base. If the chip or chips do not perform satisfactorily, the package base must be discarded along with the defective chip or chips.

Package integrated circuit having thermal enhancement and reduced footprint size


A sun visor assembly is provided incorporating a magnetic detention system. That assembly includes a sun visor body, a ferromagnetic element held in that body and a permanent magnet in a headliner of the vehicle. The permanent magnet and the ferromagnetic element are aligned so that the body is attracted toward the headliner and positively held in a home position adjacent the headliner.

Sun visors must maintain a sufficient retention force to overcome the weight of the sun visor blade or body and hold the sun visor against the headliner in the home or storage position. This is necessary in order to maintain the sun visor in place and prevent it from swinging down unintentionally from the home position. Less critically, a weak retention force also allows the visor to flutter when the vehicle shakes, creating an annoyance and a perceived lack of quality.
Current visor technology utilizes a leaf spring built into the visor support rod upon which the body is pivotally mounted to retain the sun visor in the home position. Such a construction is disclosed in, for example, U.S. Pat. No. 4,394,043 to Moulding et al. This strategy counters the weight of the visor body by applying a moment at the base of the visor body. Unfortunately, this method of retention generates significant bending stresses on the sun visor body forcing visor construction material and thickness selection.
The flaw with existing retention technology is that the retention forces are only applied at the rod. In cases where detention is the limiting factor on sun visor body stiffness applying a retention force at the end of the visor opposite the rod would enable thinner and lighter visor body construction. A further disadvantage to the existing technology is that the leaf spring retention mechanism is built for a specific angle at which the sun visor locks into detention so that it is held in the home position. Disadvantageously, a single vehicle program may need multiple sun visor retention spring designs to accommodate variations in headliner geometry which often varies, for example, from a standard roof vehicle to a vehicle incorporating a moon roof.
The sun visor that is the subject matter of this document incorporates a magnetic detention system so as to provide a retention force at the end of the sun visor body opposite the rod to thereby enable construction of the sun visor body from thinner and lighter materials. Further, the magnetic detention system is effective for maintaining a sun visor body in the home position over a wider range of geometries or configurations including for both standard roof and moon roof equipped vehicles.

Sun visor assembly incorporating a magnetic detention system


Apparatus for substantially eliminating exposure to live parts in a load center includes a bus assembly with male-terminal stabs which are capped with nonconductive material. A nonconductive structure covers the bus assembly and allows only the stabs to pass into the interior of circuit breaker compartments. A shutter assembly in each circuit breaker compartment has a nonconductive shutter plate that moves only in the Z axis to provide access to the stabs when a circuit breaker is inserted with a Z axis motion. Inserting the circuit breaker in the load center causes a shutter plate latch to open and depress the shutter. When the circuit breaker is removed from the load center, the shutter plate is biased upward and latched in a position over the stabs. No live touch points are available in the load center.

An electrical panel or panelboard, has a main bus and individual connection points on the bus that are connectable to electrical devices, such as circuit breakers for branch conductors and any other electrical devices designed to be installed for a branch circuit. Because the circuit breakers, sometimes referred to herein simply as 'breakers" for convenience, and other branch electrical devices are typically mounted directly to the panelboard, an operator and/or tools may come in contact with exposed conductors in the panelboard when installing or removing the circuit breakers from the panelboard. Thus, it is recommended that power be shut off to the panelboard as a precaution when electrical devices are being installed or removed. However, it may be considered desirable in some cases to keep the panelboard energized to prevent an electrical hazard as a consequence of deenergization, or operators may intentionally keep the power on in the interest of saving time. Moreover, shutting off power to the panelboard can be a major inconvenience, especially for data centers, hospitals, and other critical applications that require a high availability power source.
Thus, a need exists for an improved way to safely insert and remove a circuit breaker or other switching equipment from an electrical panel as part of a larger scheme for installing and removing branch circuit devices without deenergizing the electrical panel. Measures to prevent unintentional contact with live, i.e. energized, conductors are often known as "finger safe" provisions. Work on energized equipment will be known herein as 'live work". Particular panelboards, oftentimes called load centers, are front-accessible, wall-mounted panelboards, and typically for low voltage light, heat or power circuit applications, which have miniature circuit breakers to define and protect each branch circuit. Due to their size, design, and economic constraints, load center-type panel boards can present unique challenges for the above considerations.

One axis shutter with a pin-based bus system for miniature circuit breaker load centers


An LED lamp conversion module for converting an outpost lighting fixture from incandescent or halogen lighting to LED lighting, the conversion module including a base and an LED lamp attached to the base, where the LED lamp has at least one LED. Electronics are adapted to illuminate the at least one LED of the LED lamp when powered with a current. The conversion module also includes an electronic connection member in electrical communication with the electronics. The conversion module may be used to replace an incandescent or halogen lamp in an outpost lighting fixture by connecting the base to the outpost lighting fixture and connecting the electronic connection member to a power source of the outpost lighting fixture.

The present invention relates to lighting devices, and in particular, conversion modules that may be used to retrofit existing incandescent or halogen lamps in decorative low voltage landscape lighting fixtures with more efficient light emitting diode ("LED") lights.
For many years business and homeowners have installed path lighting at ingress and egress locations on their property, both for aesthetics and safety. Historically, that lighting consisted of a series of electrically interconnected lighting outposts each comprising one or more incandescent or halogen lamps. Today, there are available more efficient LED lamps that use +/− 1/20th the power of an incandescent light and last +/−20 years, all while outputting a comparable number of lumens as an incandescent lamp. However, heretofore there has been no way to retrofit the ubiquitous existing incandescent or halogen decorative low voltage landscape lighting fixture outposts with the more efficient LED lamps.


A positive resist layer formed on a translucent substrate is subjected to exposure and development to form circular resist patterns disposed near each other at a predetermined distance. The exposure pattern has an opening of a plurality of circular ring shape surrounding the plurality of resist patterns. The opening may have a width equal to the predetermined distance. Since the width of the opening is constant over the whole outer periphery of each resist pattern, uniform exposure can be realized at all positions along the periphery to form a perfect circle shape. After a convex lens shape is given to each resist pattern by heating and reflow process, the convex lens shape is transferred to the substrate by dry etching process using the resist patterns as a mask to form a microlens array with convex lenses.

A) Field of the Invention
The present invention relates to a microlens array manufacture method which transfers lens shapes to a transparent substrate or underlying layer by etching using a resist pattern as a mask, and to a microlens array produced.
B) Description of the Related Art
A microlens array having regularly aligned microlenses is used in a photocoupler for an optical fiber array, an optical integrated circuit, a solid state imager, an optical system of an electronic copy machine, a liquid crystal display and the like. According to a conventional manufacture method for such a microlens array, circular positive resist patterns are formed and changed to convex lens shapes by heating and reflow process, and thereafter the convex lens shapes of the positive resist patterns are transferred to a substrate by a dry etching process (for example, refer to Japanese Patent Laid-open Publication No. HEI-7-174903).
With this method, as shown in FIG. 7, on one principal surface of a quartz substrate 1, a necessary number of circular positive resist patterns 2a to 2d are disposed in line. Each resist pattern is spaced from other resist patterns so as not to contact each other. The regions outside the circular patterns 2a to 2d are exposed to leave un-exposed circular patterns. Next, the resist patterns 2a to 2d are heated and reflowed to form convex lens shapes (spherical convex shapes) by a surface tension. Thereafter, by using the resist patterns 2a to 2d as a mask, the substrate is dry-etched to transfer the lens shapes of the resist patterns to the principal surface of the substrate. In this manner, a microlens array can be formed on the substrate 1, having convex lenses of circular plan shapes linearly aligned in correspondence with the resist patterns 2a to 2d.
Generally, a larger exposure energy is required at a narrower exposure line (or area) width, when resist patterns are formed by subjecting a positive resist layer to exposure and development process. If the exposure area is narrower, a higher exposure energy is needed to transfer the mask image at a high fidelity. In the example shown in FIG. 7, a larger exposure energy is required at a position nearer to the center line Lc intersecting the centers of the resist patterns 2a to 2d. An exposure process is performed at such an exposure energy as proper resist patterns are formed on the center line Lc. With this setting, although proper exposure is performed on the center line Lc along an X direction, the exposure line (or area) width becomes broader at a position remoter from the center line Lc in a Y direction perpendicular to the X direction, resulting in excessive exposure. Proper resist patterns in conformity with the reticle patterns cannot be obtained.
FIG. 8 shows cross-section of a convex lens La formed on the substrate 1 by transferring the resist pattern 2a, the convex lens La corresponding to the resist pattern 2a formed by the above-described method. Lx and Ly indicate the cross section of the lens La along the X and Y directions. As described above, although the lens pattern 2a is subjected to proper exposure on the center line Lc along the X direction, excessive exposure is performed along the Y direction away from the center line Lc. The lens La is not a perfect circle, and the radius of curvature in the X direction becomes larger than that in the Y direction. Thus, a focal point Py in the Y direction becomes nearer to the substrate than a focal point Px in the X direction. A focal length difference (astigmatism) between the sagittal direction (X direction) and the meridional direction (Y direction) becomes large so that the optical characteristics are degraded.


A coupling between a motor vehicle steering shaft and a motor vehicle steering wheel including a first coupling element on the steering wheel having a cavity therein, a second coupling element on the steering shaft plugged into the cavity in the first coupling element, and a latch responsive to relative rotation between the first and the second coupling elements to couple together for unitary rotation the first and the second coupling elements with substantially zero lash therebetween. The latch includes a plurality of lugs on the second coupling element seated in extensions of the cavity in the first coupling element, a plurality of ramps in the cavity extensions operative to eject the lugs from the cavity extensions concurrent with relative rotation between the first and the second coupling elements, a plurality of sockets in the first coupling element, and a plurality of springs operative to thrust the lugs into corresponding ones of the sockets. The sockets and the lugs are shaped to wedge together to eliminate dimensional clearance, i.e., lash, which would otherwise permit relative rotation and relative linear translation between the first and the second coupling elements.

Commonly, a motor vehicle steering wheel is retained on the end of a motor vehicle steering shaft by a nut on the shaft clamped against the center of the steering wheel. The nut in the center of the steering wheel complicates the task of accommodating additional elements on the steering wheel, e.g., supplemental inflation restraint apparatus, and delays the attachment of such additional elements until after the steering wheel is mounted on the steering shaft and secured by the nut. U.S. Pat. No. 5,536,106, issued Jul. 16, 1996 and assigned to the assignee of this invention, describes a coupling between a motor vehicle steering shaft and a motor vehicle steering wheel in which a plunger on the steering wheel snaps into a notch in the steering shaft when a polygonal-shaped end of the steering shaft is plugged into a correspondingly shaped socket in the steering wheel. A coupling according to this invention between a motor vehicle steering shaft and a motor vehicle steering wheel is a novel alternative to the coupling described in the aforesaid U.S. Pat. No. 5,536,106.

Coupling between steering wheel and steering shaft


A system for supplying a working fluid to a combustor includes a fuel nozzle and a combustion chamber downstream from the fuel nozzle. A flow sleeve circumferentially surrounds the combustion chamber, and fuel injectors provide fluid communication to the combustion chamber. A distribution manifold circumferentially surrounds the fuel injectors and defines an annular plenum. A fluid passage through the distribution manifold provides fluid communication through the distribution manifold. A radial cross-sectional area of the annular plenum varies around the flow sleeve. A method for supplying a working fluid to a combustor includes flowing a working fluid through a combustion chamber, diverting a portion of the working fluid through a distribution manifold that circumferentially surrounds fuel injectors circumferentially arranged around the combustion chamber, and changing at least one of a pressure or flow rate of the diverted portion of the working fluid.

Combustors are commonly used in industrial and power generation operations to ignite fuel to produce combustion gases having a high temperature and pressure. For example, gas turbines typically include one or more combustors to generate power or thrust. A typical gas turbine used to generate electrical power includes an axial compressor at the front, one or more combustors around the middle, and a turbine at the rear. Ambient air may be supplied to the compressor, and rotating blades and stationary vanes in the compressor progressively impart kinetic energy to the working fluid (air) to produce a compressed working fluid at a highly energized state. The compressed working fluid exits the compressor and flows through one or more nozzles into a combustion chamber in each combustor where the compressed working fluid mixes with fuel and ignites to generate combustion gases having a high temperature and pressure. The combustion gases expand in the turbine to produce work. For example, expansion of the combustion gases in the turbine may rotate a shaft connected to a generator to produce electricity.
Various design and operating parameters influence the design and operation of combustors. For example, higher combustion gas temperatures generally improve the thermodynamic efficiency of the combustor. However, higher combustion gas temperatures also promote flashback or flame holding conditions in which the combustion flame migrates towards the fuel being supplied by the nozzles, possibly causing severe damage to the nozzles in a relatively short amount of time. In addition, higher combustion gas temperatures generally increase the disassociation rate of diatomic nitrogen, increasing the production of nitrogen oxides (NOX). Conversely, a lower combustion gas temperature associated with reduced fuel flow and/or part load operation (turndown) generally reduces the chemical reaction rates of the combustion gases, increasing the production of carbon monoxide and unburned hydrocarbons.
In a particular combustor design, one or more fuel injectors, also known as late lean injectors, may be circumferentially arranged around the combustion chamber downstream from the nozzles. A portion of the compressed working fluid exiting the compressor may flow through the fuel injectors to mix with fuel to produce a lean fuel-air mixture. The lean fuel-air mixture may then be injected into the combustion chamber for additional combustion to raise the combustion gas temperature and increase the thermodynamic efficiency of the combustor.
The late lean injectors are effective at increasing combustion gas temperatures without producing a corresponding increase in the production of NOX. However, the pressure and flow of the compressed working fluid exiting the compressor may vary substantially around the circumference of the combustion chamber. As a result, the fuel-air ratio flowing through the late lean injectors can vary considerably, mitigating the beneficial effects otherwise created by the late lean injection of fuel into the combustion chamber. Previous attempts have been made to achieve a more uniform flow of working fluid through the late lean injectors. For example, scoops or shrouds have been installed over a portion of the fuel injectors to more evenly regulate the flow of working fluid through the fuel injectors. However, an improved system and method for reducing the variation in the pressure and/or flow of the working fluid flowing through the late lean injectors would be useful.

System and method for supplying a working fluid to a combustor via a non-uniform distribution manifold


A slide rail includes a first slide, a second slide, and a third slide, each of the first slide, the second slide, and the third slide comprising a pair of sidewalls. The first slide further includes a bottom wall, the pair of the sidewalls are extended from two edges of the bottom wall respectively. The second slide is received in a space bounded by the bottom wall and the sidewalls of the first slide; the sidewalls of the second slide extend out from the space to contact the sidewalls of the third slide.

1. Field of the Invention
The present invention generally relates to slide rails. Particularly, the present invention relates to slide rails with adequate space between slides.
2. Description of Related Art
Slide rails are used for guiding objects, such as drawers, to be pushed into or pulled out from bodies, such as furniture. There are many kinds of slide rails, some have ball bearings and others do not. Slide rails having ball bearings are easy to be pulled or pushed, for they have little friction. However, the ball bearings add to the cost of the slide rails, and brackets for supporting the ball bearings tend to break, which causes the slide rails to become unusable. Slide rails without ball bearings have lower costs than those having ball bearings. Such slide rails have at least two slides movable relative to each other.
In the slide rails, locks are typically installed between the slides for preventing unwanted movement of the slides. Only when the locks are unlocked, the slides may move relative to each other. Therefore, adequate space between the slides is needed for installing the locks.

Hong Fu Jin Precision Industry (ShenZhen) Co., Ltd.


Methods, components and systems for implementing secure and efficient broadcast encryption schemes with configurable and practical tradeoffs among a pre-broadcast transmission bandwidth t, a key storage cost k, and a key derivation cost c, in which the schemes use subtree difference and key decomposition to generate secondary keys, use the secondary keys to encrypt the broadcast and generate ciphertexts, and use the RSA encryption scheme to implement derivability between the primary keys and the secondary keys. To decrypt the broadcast, a privileged user uses one of its primary keys to derive a secondary key, which is used to decrypt the broadcast. The product of key derivation costc and the key storage cost k is at most (2a−log a−2)loga n, when n is the number of users, 1≦b≦log n, a=2b, and revoked users r<n/3.

1. Field of the Invention
The present invention relates to broadcast encryption, and more specifically to implementing efficient broadcast encryption schemes with configurable tradeoffs among pre-broadcast transmission bandwidth, key storage cost, and key derivation cost.
2. Description of the Related Art
Broadcast encryption schemes allow a center to transmit encrypted data over a broadcast channel to a large number of users such that only privileged users, a select subset P of the users, can decrypt it. Traditional applications include Pay TV, content protection on CD/DVD/flash memory, secure Internet multicast of privileged content such as video, music, stock quotes, news stories, and the like. However, broadcast encryption schemes can be used in any setting that might require selective disclosure of potentially lucrative content.
Broadcast encryption schemes typically involve a series of pre-broadcast transmissions, at the end of which the users in P can decrypt a broadcast session key bk. The remainder of the broadcast is then encrypted using bk.
In terms of efficiency, the most important parameters of the broadcast encryption schemes are: 1) the number of pre-broadcast transmissions t made by the center; 2) the maximum amount of keying material k a user must persistently store; and 3) the maximum amount of computation c the user must perform to decrypt the broadcast session key bk from the pre-broadcast transmissions. In a system of n users, r of which are to be revoked, a broadcast encryption scheme must find a favorable balance among the parameters t, k, and c.
One variant of the broadcast encryption problem, for which finding an efficient solution has been difficult, is the so-called "stateless receiver" case. This variation includes the following requirements:
1. Each user in the privileged set P can decrypt the broadcast by himself.
2. No coalition of users outside the privileged set P can decrypt the broadcast.
3. Consecutive broadcasts may address unrelated privileged sets.
4. A user need not update its keys if other users leave or join the privileged set.
5. A user's keys are unaffected by its viewing history.
In this case, users are provided with some initial key or set of keys, and can only use this keying material when decrypting future broadcasts. Stateless receivers can store only the keys given at the initial stage such as manufacturing time. As a result, every broadcast message must contain enough information to enable non-revoked receivers to obtain the current session key using their initial receiver keys. The above definition can also be extended to allow some threshold of free riders, i.e. users outside of the privileged sets who might be able to decrypt the broadcast.
The stateless model is preferable since it does not involve any type of key update procedure, which is not only costly but also introduces additional points of failure. Since keys are not updated in the stateless model, they can be embedded in non-volatile tamper-resistant storage. This enhanced security reduces the possibility of piracy in broadcast settings.
The problem of stateless receiver broadcast encryption, a practical trade-off among pre-broadcast transmissions t, user key storage k, and user decryption computation c, is well-known in the literature. However, previously proposed solutions are all inefficient with respect to at least one of the parameters. Essentially, these proposals belong to one of three categories: 1) schemes using error-correcting codes, 2) schemes using key trees, and 3) schemes using RSA.
The schemes using error-correcting codes require the number of revoked user r be specified in advance, and one or more of the parameters t, k and c be at least linear with r. However, the number of revoked users r changes from time to time in practice. The key-tree-based stateless receiver broadcast encryption scheme needs to store log n (or more) keys in limited devices, such as tamper-resistant smart cards. The user key storage k is very high.
The RSA public-key encryption scheme was proposed in R. L. Rivest, A. Shamir and L. Adleman (RSA), A Method for Obtaining Digital Signatures and Public—Key Cryptosystems—Comm. Of the ACM (1978), vol. 21, 120-126. According to the RSA scheme, a keyholder chooses two large prime numbers p and q, and two exponents e and d such that ed≡1(mod Φ(n)), where Φ(n)=LCM(p−1)(q−1). The scheme publishes e and the product n=pq, but keeps d, p and q secret. To encrypt a message mε Z/nZ, a sender computes me (modn) and transmits this number to the keyholder. To decrypt, the keyholder computes m≡(me)d(modn). Over the past 27 years, numerous cryptographic inventions have used ideas related to RSA that were not envisioned by the inventors of RSA. The RSA encryption scheme does not, in itself, address the problem of broadcast encryption.
In S. G. Akl and P. D. Taylor, Cryptographic Solution to a Multilevel Security Problem—Crypto '82, Plenum Press (1982), 433-450, Akl and Taylor used techniques related to RSA to handle access control. In Akl-Taylor, each user is a member of one or more security classes. For any fixed set of security classes, each user in their scheme obtains a single "master key" that enables it to gain access to any security class of which it is a member. These security classes form a partially-ordered set (poset) under the inclusion relation. This poset can be modeled as a directed acyclic graph (DAG). Akl-Taylor uses RSA to generate a set of immiscible keys tailored for a given DAG. Nonmembers of a security class cannot collude to gain access to the security class. The center generates an RSA modulus n=pq and fixes some m∈(Z/nZ)*. Keys have the form ki=m1/ei(modn) for publicly known ei. An important property of RSA is that, given e, it is computationally easy to compute me (mod n) for any m, but it is computationally hard to compute m1/e (mod n), i.e., it is easy to compute eth powers but hard to compute eth roots. Thus, ki→kj if ej divides ei. In other words, if ej divides ei, keys kj can be computed from keys ki. More generally,{ki1, . . . kiz}→kj, if and only if ej divides LCM (ei1, . . . eiz)  (1)
Thus, key derivability is completely dictated by the factorization of the ei's. In Akl-Taylor, each vertex vi in the DAG is associated with a distinct prime pi, and ei=Πvi→vj Pj. The keys are immiscible, and nonmembers of a security class cannot collude to gain access. However, the cost of computing kj from ki in Akl-Taylor is very high. In addition, the Akl-Taylor scheme does not address the problem of broadcast encryption, where the privileged subsets may change from one broadcast to another.
In T. Asano, A Revocation Scheme with Minimal Storage at Receivers—Asiacrypt '02, Lecture Notes in Computer Science 2501 (2002), Springer-Verlag, 433-450, Asano proposes a stateless receiver broadcast encryption scheme in which each user only needs to store a single key. According to the Asano scheme, users are positioned as leaves in a hierarchical tree such that each node in the tree (other than the root) has a-1 siblings, wherein a denotes the branching factor. Each user is allowed to derive (2a−1−1)logan+1 subset keys, where each subset contains an ancestor of the user's leaf, together with some number (but not all) of the ancestor's siblings. These subsets form a poset under the inclusion relation, and key derivability can be modeled by a DAG. A privileged user can use its key to derive secondary keys, one of which is used to recover the broadcast session key bk and then the broadcast. The Asano scheme uses techniques related to the RSA encryption scheme to dictate which keys can be derived from other keys. However, the derivability graph that the Asano scheme uses is highly non-optimal. Fixing the number of transmissions to be t=O(r loga(n/r)), the user's computational requirement becomes c=O(2a loga n), which quickly becomes huge as a increases. Thus, although the Asano scheme has the advantage of requiring a user to store only one key, and of being able to trade off the number of pre-broadcast transmission for user decryption computation, the computation increases at an unacceptable rate as the transmission decreases.
In M. Luby and J. Staddon, Combinatorial Bounds for Broadcast Encryption—Eurocrypt '98, Lecture Notes in Computer Science 1403 (1998), Springer-Verlag, 512-526, Luby and Staddon considered a variant of unconditionally secure one-time broadcast encryption schemes (OTBESs). In this model, each user u is given some set K′u of keys. The Luby-Staddon scheme proves a combinatorial bound relating maxu|K′u| and the number of pre-broadcast transmissions t—namely,
                                          max            u                                                                    K              u              ′                                                  ≥                              (                                                                                (                                                                                n                                                                                r                                                                                )                                                        1                    /                    t                                                  t                            -              1                        )                    /          r                                    (        2        )
where n is the total number of users, and r is the number of users that are not entitled to the broadcast. However, there is no derivability among the keys, and keys are used only once (as a one-time pad).
Accordingly, there has been a need for a broadcast encryption scheme with an acceptable and configurable tradeoff among t, k and c.