An interpolation filter without a FIFO memory is configured as a cascade arrangement of simpler interpolation sub-filters that are operated in reverse order. The interpolation sub-filter that produces the highest sampling frequency is operated first, followed by interpolation sub-filters that operate at successively lower sampling frequencies. Computational independence of the cascaded sub-filters is guaranteed by adding delays to sampled and filtered signals. Delays are implemented by operating each of the cascaded sub-filters using prior filtering results that are computed during a previous sampling interval. A small increment to random-access memory is required for storing the successively delayed signals. The digital signal processor performing the filtering process is stalled for one clock cycle at the time a filtered signal sample is outputted so that the outputted signal sample can be produced without a timing conflict.

Linear filters implemented with digital signal processing, generally with constant coefficients, are widely used in electronic systems, particularly in systems configured with digital logic. For example, digital filters are widely used in high fidelity audio systems, cellular telephones, speakerphones, high performance television and radio receivers, speech recognition, and numerous other applications requiring linear processing of a band-limited signal.
Digital interpolation filters are generally included in system designs to increase a signal sampling rate before a digital-to-analog (D/A) conversion process. The Nyquist rate, as is well understood in the art, is the minimum sampling rate for a band-limited signal without losing its information content. However, upsampling ("interpolating") a band-limited signal to rates beyond the Nyquist rate allows D/A conversions with fewer bits of precision than are used for the original signal while preserving the original signal's information content. Reducing the number of bits in D/A converters often results in substantial cost reduction for a D/A device and increased conversion speed. Thus, generating oversampled signals is a frequent design approach in high performance systems such as high performance audio reproduction systems.
To achieve high filtering performance such as a flat pass band, a flat stop band, and a steep inter-band transition, high order filters are required. For example, the number of filter delay taps required to implement an FIR filter with a pass-band ripple of ±r1 centered around unity, a stop-band ripple of ±r 2 centered around zero, a transition bandwidth of Ftransition Hz, and a sampling frequency of Fsampling Hz is approximately, as described in R. A. Haddad, et al., "Digital Signal Processing: Theory, Applications and Hardware," W.H. Freeman and Co., 1991, p. 199
                                          -            10                    ·                                    log              10                                                  (                                                r                  1                                ·                                  r                  2                                            )                                      -        13                    14.6        ·                              F            transition                                F            sampling                                +    1    ,which demonstrates the rapid growth of the number of taps necessary to implement a filter as its transition bandwidth is reduced. Thus, high performance digital filters with more than 50 or 100 taps are not uncommon for known filters with narrow transition bandwidths.
Filters configured with many taps inherently require that a significant number of digital operations be performed at a high repetition rate. This, in turn, requires that substantial chip area must be dedicated when a high-order filter is implemented with an integrated circuit, or else a high performance digital signal processor must be designed into the end product. Either of these alternatives can result in recognizable cost and power increases in the end product, and, for portable systems, a reduction in battery life.
Digital filters are usually implemented with finite-duration impulse response (FIR) filters, so named because an input signal with a limited time duration produces an output signal with a limited time duration. FIR filters, unlike infinite-duration impulse response (IIR) filters, do not exhibit stability problems because their non-recursive structure produces an output signal that only depends on ordinary numerical operations on an input signal, and with limited time delays. FIR filters have no corresponding lumped-parameter analog equivalent. FIR filters are less dependant on numerical quantization and, unlike IIR filters, can be easily designed without substantial phase error that would otherwise contribute to waveform distortion of the output signal. FIR filters are often easier to design than IIR filters because their coefficients are precisely their impulse responses. But a high performance FIR filter, like a corresponding IIR filter, bears a system cost for substantial numerical computation, particularly for multiplication of the input signal by a filter coefficient for each of the many filter taps, making a recognizable contribution to the cost of the end product.
A broad research effort has been made over the past decades to reduce the necessary computation for digital filters, particularly for high-order FIR and IIR filters, and has produced several significant results. An article by J. O. Coleman, et al., "Fractions in the Canonical-Signed Digit Number System," 2001 Conf. on Information Sciences and Systems, Mar. 21, 2001, pp. 1-2, which is referenced and incorporated herein, describes the use of canonical signed digits (CSD) for the representation of binary numbers. Using a CSD representation recognizes and takes advantage of the fact that subtraction is no more complex than addition in binary arithmetic and both are much simpler than multiplication which is generally implemented with a series of resource-consuming shifts and adds corresponding to the number of "1" bits in the multiplier.
Other prior research efforts have produced further simplifications to the computation necessary to support FIR and IIR filters and include:                using FIR filters with symmetrical (or anti-symmetrical) impulse response that inherently maintain linear phase delay in the output signal. Such filters can be implemented with half as many multiplications as a non-symmetrical filter.        using "half-band filters," which are FIR filters that have transforms that are even functions of frequency and which have odd symmetry about a half-bandwidth point, which produce both a symmetric impulse time response as well as zero impulse time response for the even-numbered time steps, obviating the need to calculate the response at the even-numbered points.        structuring decimation and interpolation filters as a series of cascaded stages, with each stage operating with smaller steps of decimation or interpolation, and configuring the more rapidly executed steps with lower order sub-filters. (Decimation and interpolation filters are digital filters that reduce or increase the number of sample points of an input signal by a factor of M, and typically constrain M to be 2n where n is an integer exponent.)        using efficient digital structures such as tree adders, Homer's nested multiplication, etc., and general custom logic to perform arithmetic operations in minimal time.
Despite these advances in digital filter implementations, a remaining obstacle to low cost filter design, particularly for interpolation filters, is the need to include a dual-port FIFO ("first in/first out") memory to supply the output data in a real-time application of a filter configured as a sequence of simpler, cascaded sub-filters, where each sub-filter operates on the output of the previous filter, and each sub-filter operates at a different repetition rate. The need for FIFO memory arises in systems configured to use a selectable upsampling rate because the timing for availability of delayed and filtered samples in the digital computation depends on the selected upsampling rate, and leads to impractical or essentially unworkable circuit or software logical structures in these flexible arrangements, or else to designs that are not cost effective for the marketplace. A dual-port FIFO memory in prior-art designs provides the interface between an ALU (arithmetic and logic unit) that performs the actual filter calculation for the cascaded sub-filters operating at the different repetition rates and the digital logic (the "glue" logic) that outputs the selected filtered samples from the cascaded sub-filters in the right order, and at the right time. Dual-port FIFO memories are a significant cost element in digital filter designs, particularly for high-order filters, usually requiring substantial die area for their implementation. A dual-port FIFO memory often consumes as much as 30% of the die area for a custom chip that can perform flexible upsampling, for example, a device that can selectively execute multiple upsampling rates for high performance, multi-channel audio applications. The additional area for a FIFO memory is important because systems may be configured with six or more independent audio channels, each requiring a separate interpolation filter. A significant contributor to the substantial die area required by filters with FIFO memory is the need for extensive interconnections between portions of the operative filter logic that are inherently separated on the die. FIFO memory macros also require special power and ground structures around them, adding to the real estate on the die. For custom filters that operate at only one upsampling rate such as sample rate doubling, extensive logical design can sometimes be included in the device to avoid the FIFO memory problem. But a majority of designs that can accommodate flexible upsampling rates have not avoided this problem.
Thus, the prior art approach uses a digital interpolation filter to produce a filtered output signal at a higher sampling rate than the sampling rate of an input signal, and a known simplification of a digital interpolation filter uses a cascade arrangement of simpler interpolation sub-filters that each perform a smaller interpolation step, such as 2:1 interpolation, for a larger step of interpolation, such as 8:1 interpolation. The first cascaded interpolation sub-filter of the prior art operates on the input sampled data sequence and produces a filtered signal at twice the input signal sampling rate. The first cascaded interpolation sub-filter is followed by a second cascaded interpolation sub-filter that operates on the interpolated signal produced by the first interpolation sub-filter and produces a filtered signal at four times the sampling rate. The second cascaded interpolation sub-filter is followed, in turn, by a third cascaded interpolation sub-filter that produces a signal at eight times the sampling rate, etc. Thus, the first cascaded interpolation sub-filter operates on the input signal and produces an interpolated signal at a higher sampling rate, followed by a second interpolation sub-filter that operates on the interpolated signal and produces a further interpolated signal at a yet higher sampling rate, etc., which makes each succeeding filtering stage dependent on the previous filtering stage, and determines the necessary order in which each stage must be executed. In addition, the entire computation must be completed before the first filtered output signal is required, i.e., at the highest repetition rate. The prior art may also use CSD and other digital efficiencies to reduce the computational load for a digital filter. To accommodate a flexible over-sampling rate for the filtered output signal, the prior art necessarily uses a dual-port FIFO memory with its attendant cost in device area to provide the output signal samples in the correct sequence and with the correct timing.
A need thus exists for a filter design that can eliminate the dual-port FIFO memory for filters configured with cascaded sub-filtering stages. Digital interpolation and decimation filter implementations such as FIR filter implementations configured with cascaded stages, particularly in systems requiring removal of spectral components that produce aliasing after interpolation or decimation of an input sampled signal, can benefit from designs that do not have need for a dual-port FIFO memory.

Method and apparatus for efficient multi-stage FIR filters


A light source optical system includes a micro lens array, a condenser lens unit, and a dichroic surface. In a direction orthogonal to an optical axis in a cross section parallel to a normal of the dichroic surface and the optical axis of the condenser lens unit, a width of the dichroic surface is narrower than a width of the condenser lens unit. A light source optical system satisfies a predetermined conditional expression.

Field of the Invention
The present invention relates to a light source optical system and a projection display apparatus employing the same.
Description of the Related Art
In recent years, a projector has been developed that irradiates a fluorescent body with a light flux emitted from high output laser diodes (hereinafter referred to LDs) as an excitation light, and includes a wavelength-converted fluorescent light as a light source light. In such a projector, the brightness of the projector can be increased by increasing the number of LDs and/or increasing the output of each LD.
However, the light density of a light source spot formed on a fluorescent body surface is increased when the strength of incident light onto the fluorescent body is increased to increase the brightness. As a result, a problem such as reduction of the light conversion efficiency occurs because of a luminance saturation phenomenon, and therefore, the brightness proportional to the increase in the output of the LD cannot be obtained.
A technique discussed in United States Patent Application Publication No. 2012/0133904 is known as a technique to solve such a problem. United States Patent Application Publication No. 2012/0133904 discusses a configuration in which two fly-eye lenses are provided on the latter stage of an optical system for compressing light fluxes from a plurality of LDs. Such a configuration can uniformize the light density of the light source spot formed on the fluorescent body and suppress the occurrence of an area having an extremely high light density to suppress the reduction of the light conversion efficiency described above.
The configuration discussed in United States Patent Application Publication No. 2012/0133904 requires not only the LD for exciting the fluorescent body but also an LD for guiding a blue color light to a color separating and combining system and an optical system therearound, leading to increasing the entire apparatus size.

Light source optical system and projection display apparatus employing the same


A main module of an object oriented computer program is independent of the software domain and can be dynamically configured or reconfigured at runtime by domain specific dynamic link libraries. This main module is a generic main which is configured by a service configurator. A framework connector is provided as are a communications component and a asynchronous/asychronous management component.

1. Field of the Invention
The present invention relates to generally to a generic main computer program module that is dynamically configured at run time, and in particular to a network daemon using a service configuration pattern to configure a generic main object in a network computing environment.
2. Description of the Related Art
As set forth in U.S. Pat. No. 5,499,365, full incorporated herein by reference, object oriented programming systems and processes, also referred to as "object oriented computing environments," have been the subject of much investigation and interest. As is well known to those having skill in the art, object oriented programming systems are composed of a large number of "objects." An object is a data structure, also referred to as a "frame," and a set of operations or functions, also referred to as "methods," that can access that data structure. The frame may have "slots," each of which contains an "attribute" of the data in the slot. The attribute may be a primitive (such as an integer or string) or an object reference which is a pointer to another object. Objects having identical data structures and common behavior can be grouped together into, and collectively identified as a "class."
Each defined class of objects will usually be manifested in a number of "instances". Each instance contains the particular data structure for a particular example of the object. In an object oriented computing environment, the data is processed by requesting an object to perform one of its methods by sending the object a "message". The receiving object responds to the message by choosing the method that implements the message name, executing this method on the named instance, and returning control to the calling high level routine along with the results of the method. The relationships between classes, objects and instances traditionally have been established during "build time" or generation of the object oriented computing environment, i.e., prior to "run time" or execution of the object oriented computing environment.
In addition to the relationships between classes, objects and instances identified above, inheritance relationships also exist between two or more classes such that a first class may be considered a "parent" of a second class and the second class may be considered a "child" of the first class. In other words, the first class is an ancestor of the second class and the second class is a descendant of the first class, such that the second class (i.e., the descendant) is said to inherit from the first class (i.e., the ancestor). The data structure of the child class includes all of the attributes of the parent class.
Two articles providing further general background are E. W. Dijkstra, The Structure of "THE" Multiprogramming System, Communications of the ACM, Vol. 11, No. 5, May 1968, pp. 341-346, and C. A. R. Hoare, Monitors: Operating Systems Structuring Concepts, Communications of the ACM, Vol. 17, No. 10, October, 1974, pp. 549-557, both of which are incorporated herein by reference. The earlier article describes methods for synchronizing using primitives and explains the use of semaphores while the latter article develops Brinch-Hansen's concept of a monitor as a method of structuring an operating system. In particular, the Hoare article introduces a form of synchronization for processes and describes a possible method of implementation in terms of semaphores and gives a proof rule as well as illustrative examples.
As set forth in the Hoare article, a primary aim of an operating system is to share a computer installation among many programs making unpredictable demands upon its resources. A primary task of the designer is, therefore, to design a resource allocation with scheduling algorithms for resources of various kinds (for example, main store, drum store, magnetic tape handlers, consoles). In order to simplify this task, the programmer tries to construct separate schedulers for each class of resources. Each scheduler then consists of a certain amount of local administrative data, together with some procedures and functions which are called by programs wishing to acquire and release resources. Such a collection of associated data and procedures is known as a monitor.
The adaptive communication environment (ACE) is an object-oriented type of network programming system developed by Douglas C. Schmidt, an Assistant Professor with the Department of Computer Science, School of Engineering and Applied Science, Washington University. ACE encapsulates user level units and WIN32 (Windows NT and Windows 95) OS mechanisms via type-secured, efficient and object-oriented interfaces:                PC mechanisms—Internet-domain and UNIX-domain sockets, TLI, Named pipes (for UNIX and Win 32) and STREAM pipes;        Event multiplexing—via select( ) and poll( ) on UNIX and WaitForMultipleObjects on Win 32;        Solaris threads, POSIX Pthreads, and Win 32 threads;        Explicit dynamic linking facilities—e.g., dlopen/dlsym/dlclose on UNIX and LoadLibrary/GetProc on Win 32;        Memory-mapped files;        System VIPC—shared memory, semaphores, message queues; and        Sun RPC (GNU rpc++).
In addition, ACE contains a number of higher-level class categories and network programming frameworks to integrate and enhance the lower-level C++ wrappers. The higher-level components in ACE support the dynamic configuration of concurrent network daemons composed of application services. ACE is currently being used in a number of commercial products including ATM signaling software products, PBX monitoring applications, network management and general gateway communication for mobile communications systems and enterprise-wide distributed medical systems. A wealth of information and documentation regarding ACE is available on the worldwide web at the following universal resource locator:
http://www.cs.wustl.edu/ . . . schmidt/ACE-overview.html.
The following abbreviations are aor may be utilized in this application:                Thread—a parallel execution unit within a process. A monitor synchronizes, by forced sequentialization, the parallel access of several simultaneously running Threads, which all call up functions of one object that are protected through a monitor.        Synchronizations-Primitive—a means of the operating system for reciprocal justification of parallel activities.        Semaphore—a Synchronizations-Primitive for parallel activities.        Mutex—a special Synchronizations-Primitive for parallel activities, for mutual exclusion purposes, it includes a critical code range.        Condition Queue—an event waiting queue for parallel activities referring to a certain condition.        Gate Lock—a mutex of the monitor for each entry-function, for protection of an object, for allowing only one parallel activity at a time to use an Entry-Routine of the object.        Long Term Scheduling—longtime delay of one parallel activity within a condition queue or event waiting queue for parallel activities.        Broker—a distributor.
In addition, the following acronyms are or may be used herein:                AFM Asynchronous Function Manager        SESAM Service & Event Synchronous Asynchronous Manager        PAL Programmable Area Logic        API Application Programmers Interface        IDL Interface Definition Language        ATOMIC Asynchron Transport Optimizing observer-pattern-like system supporting several Modes (client/server-push/pull) for an IDL-less Communication subsystem, described herein        XDR External Data Representation        I/O Input/Output        IPC Inter Process Communication        CSA Common Software Architecture (a Siemens AG computing system convention)        SW Software

Interpretive network daemon implemented by generic main object


A laser printer includes: a main casing with two side walls; lower guiding grooves formed in the side walls; a process cartridge that is guided by the guiding grooves to be mounted in or removed from the main casing; and a lever rotatably supported by a shaft mounted on the main casing at a position near the lower guiding groove in one side wall. When the lever is rotated, a protruding part provided on one end of the lever protrudes into the lower guiding groove and engages with a fixing boss provided on the process cartridge, thereby preventing the process cartridge from moving in a direction opposite the direction in which the cartridge is mounted in the main casing.

1. Field of the Invention
The present invention relates to an image-forming device such as a laser printer, and particularly to an electrophotographic image-forming device having a removable process cartridge.
2. Description of Related Art
Process cartridges employed in laser printers and other image-forming devices, such as those disclosed in Japanese unexamined patent application publication No. HEI-10-254328, are well known in the art. This type of process cartridge is configured of a photosensitive unit housing a photosensitive drum and a charger, and a developing portion including a developing roller and a toner cartridge accommodating a developer (toner). The process cartridge can be removed from a main casing of the image-forming device in order to perform maintenance, clear paper jams, or the like.
The process cartridge is inserted through an opening formed in the main casing and guided into the image-forming position by guiding rails formed on the inside of the main casing. A spring is provided in the main casing for pulling the process cartridge into the image-forming device. When the process cartridge is mounted in the main casing, the spring prevents the cartridge from stopping short of the image-forming position and fixes the cartridge in the correct position.

Image-forming device having a removable process cartridge


A lower body support device is shown herein. The lower leg of the user is positioned such that the knee of the user rests within the area defined by a knee frame, the shin of the user rests within the area defined by a bend frame, and the ankle of the use rests in the region of an ankle frame. A strap bar means connected to the knee frame allows for the securing of a knee pad, such knee pad is user chosen, worn by the user and strapped to the knee frame via the strap bar means. A seat insert is secured to the top of the ankle frame. The user wears one leg support device on each leg. While resting on a surface, the bottom of the knee frame and the bottom of the ankle frame, and possibly the knee pad worn by the user, contact said surface. Preferably, the buttocks of the user rests on the seat insert, which transfers a significant portion of the weight of the user to the surface via the frames. The ankle frame and knee frame greatly limit the possibility of side-to-side motion. Additionally, the user may stand and walk while employing the leg support device.

1. Field of the Invention
This invention is directed toward the field of lower body support devices. More particularly, this invention relates to a lower body support device for providing improved support, stability, and mobility for users of the device.
2. Discussion of Prior Art
Many occupations require workers to assume kneeling positions in order to attend the task for which they are employed. Unfortunately, assuming a kneeling position for an extended period, or repeatedly, causes those in such a position discomfort, cramping, muscle fatigue, or other similar problems.
Many devices have been proposed over the years to alleviate the discomforts associated with kneeling positions. For instance, U.S. Pat. No. 1,296,522 to Holsey shows a simple knee pad device. Similarly, U.S. Pat. No. 1,547,166 to Davidison shows a slightly more sophisticated knee pad. However, neither device provides much in the way of actual support or cushioning. That is, even though the knee is elevated above whatever surface on which the knee pad rests, the user's weight still stresses the knee.
In U.S. Pat. No. 2,627,301 to Emmett, a knee board is shown. Although this device implements a recognizable pad to cushion the knee, it does not allow much mobility to a standing user. As such, is utility its diminished.
In U.S. Pat. No. 4,377,309 to Mengshoel another knee board device is illustrated. Through a variety of configurations, Mengshoel discloses a more portable device than previously shown. Additionally, the device has provision for a seat element, which takes some stress off the user's knees. However, the user's weight still passes through the user's ankles. Moreover, in the J-shaped ankle configuration the user's leg may separate from the pad, especially when employed in a dynamic occupational setting. Additionally, the O-shaped ankle configuration, the ability of the user to equip the device is impaired. That is, putting one's foot through the O-shaped ankle configuration is difficult.
In U.S. Pat. No. 4,772,071 to Richards, a complicated knee pad device is shown. Said device includes a frame with a knee pad section, a seat section, and a mid-shin floor engaging member. This device is hampered by its obvious complexity. Moreover, it is designed with an integrated knee pad, limiting the user to employing that knee pad exclusively. Additionally, this device is not particularly stable, being prone to side-to-side rolling.
In U.S. Pat. No. 5,865,507 to Earl, a kneeler is shown. This kneeler allows a certain amount of the user's weight to pass through the seat incorporated in the frame of the device. However, a user of the device cannot walk around with this device attached to their legs. As such, the user would have to carry such device with them, greatly diminishing its utility.
As such, there is a void in the prior art in the field of lower body support devices. The prior art lacks a device which provides improved lower body support, mobility, and stability in a less complex configuration. The present invention fills this void.


Active encapsulation compositions which are stable in the glassy state at ambient temperatures are prepared by melt extrusion of a ternary carrier blend comprising of 1) a food polymer, 2) a spice or herb, and 3) a low molecular weight sugar or polyol. Such glassy matrices are useful for the encapsulation of encapsulates, in particular, flavors and medications.

1. Field of the Invention
The present invention relates to encapsulation compositions in which an encapsulate is encapsulated in a glassy matrix by a process known as melt extrusion. More particularly, the present invention relates to flavor encapsulation compositions in which a flavoring agent is encapsulated by melt extrusion in a glassy matrix containing spices and herbs as a part of the matrix. Incorporation of spices and herbs in the matrix creates an active carrier protecting and modulating the encapsulated flavoring agents. The present invention also relates to processes for preparing such compositions.
2. Discussion of the Background
The encapsulation of encapsulates is an area of active research. In particular, the encapsulation of encapsulates such as medications, pesticides (including insecticides, nematocides, herbicides, fungicides, microbiocides, etc.), preservatives, vitamins and flavoring agents is desired for a number of reasons. In the case of medications and pesticides, encapsulation may be desired to achieve controlled release of the medications or the pesticides. For vitamins, encapsulation may be carried out to protect the vitamins from air-oxidation and, thus, to extend shelf life of the vitamins. In the case of flavoring agents, the encapsulation may be carried out to place the flavorings in an easily metered form which will release the agent at a controllable event, such as the addition of water.
It is generally known to skilled practitioners in the field of flavor encapsulation that the current practical commercial processes leading to stable, dry flavors are limited in great part to spray drying and extrusion fixation. The former process requires emulsification or solubilization of the flavor in an aqueous carrier containing the encapsulation solids, followed by rapid drying in a high temperature, high velocity gas stream and collection as a low-density bulk solid.
While spray drying accounts for the majority of commercially encapsulated flavor materials, several limitations of the process are evident. Low molecular weight components of complex or natural flavor mixtures generally exhibit high vapor pressures and are usually lost or disproportionate during the process. The resultant flavor-carriers are porous and difficult to handle. In addition, deleterious chemical reactions such as oxidation can result on surfaces exposed during and after drying. The final product, a dry, free flowing fine powder will release the encapsulate rapidly upon hydration whether rapid release is desired or not. Incorporation of spices or herbs in a significant amount in the solubilized carrier is not practical for the reason of swelling of a spice or an herb powder in water, resulting in a high viscosity and clogging atomizing wheels or nozzles during spray drying.
Some other encapsulation processes may include freeze drying, drum drying and tray drying. These processes have marginal significance due to a high processing cost and relatively poor protection of encapsulates, compared to spray drying and extrusion. The processes of drying are slow in the case of freeze and tray drying resulting in a weak glassy character generated by slow drying rather than quick cooling. Volatile flavor losses are very significant. Drum drying could be a fast process; however, loss of volatile components is very significant on the contact with a high temperature surface. All the above processes require a milling step further weakening the flavor. Moreover, the preparation step involves making a slurry where spices and herbs will swell and form a viscous dispersion that is difficult to control and process.
U.S. Pat. No. 3,971,852 discloses the use of a modified starch, gums and other food polymers with low molecular weight polyhydroxy compounds and spray drying to yield a glassy matrix with encapsulated oil at a maximum of 70-80% by volume. The system forms a shell surrounding the oil flavoring but is limited to lipophilic flavoring agents.
U.S. Pat. No. 4,532,145 discloses a process for preparing compositions in which a volatile flavorant is fixed by spray drying from a carrier solution made up of 10-30% of a low molecular weight component such as a sugar or edible food acid with the balance of the solids being a maltodextrin carbohydrate in the amount of 70-90%.
U.S. Pat. No. 5,124,162 discloses a carrier mixture composed of mono- and disaccharides (22-45%), maltodextrins (25-50%), and a high molecular weight carbohydrate such as chemically modified starch or gum acacia (10-35%) to which volatile flavoring agents are added and the subsequent dispersion is spray dried to yield a free flowing powder with a bulk density of 0.50 g/cc.
A number of technical issues are unmet by these approaches. First, thermally sensitive flavors undergo undesirable reactions including oxidation, rearrangements, and hydrolysis. Secondly, volatile components are lost or disproportionate during atomization and evaporation in the dryer. Finally, spices and herbs are not included in the compositions.
A second process route, melt injection, has been utilized to advantage with lipid-based flavors. In this technology, a melt is prepared by boiling off sufficient water from a high solids carbohydrate syrup, adding flavoring oils with an emulsifier, agitating under pressure to emulsify the oil in the melt and injecting the mixture into a chilling, dehydrating solvent bath to obtain fine rod-like filaments. After solvent removal, the matrix is reduced in size and, in some cases, coated with an anti-caking agent before being packed. See, e.g., U.S. Pat. Nos. 2,809,895; 2,856,291; and 3,704,137. Subsequent improvements in the art are disclosed in U.S. Pat. No. 3,314,803 for the encapsulation of volatiles such as acetaldehyde, and in U.S. Pat. No. 4,707,367, which discloses encapsulation of up to 35% by weight of flavor oil in the glassy matrix.
U.S. Pat. No. 4,689,235 discloses the use of modified starch-maltodextrin carriers in the range of 5 parts modified starch/95 parts maltodextrin to 95 parts modified starch/5 parts maltodextrin. The carrier is dissolved to form a syrup, water is cooked off, flavor is added and emulsified, and the melt is injected into a solvent bath.
An alternative route to encapsulating flavors is disclosed in U.S. Pat. No. 4,230,687. In this approach, high molecular weight carriers such as proteins, starches and gums are plasticized by addition of significant amounts of water in the presence of the encapsulate and subjected to a high shear dispersing process. The rubbery or plastic matrix with encapsulate is then extruded, recovered and dried to yield a stable product.
Another alternative process, melt extrusion, can be utilized for flavor fixation and encapsulation. In this process, a melting system, i.e., an extruder is employed to form the carrier melt in a continuous process. The encapsulated flavor is either admixed or injected into the molten carbohydrate carrier.
U.S. Pat. No. 4,232,047 discloses the use of a matrix comprising a fused encapsulating material selected from the group consisting of starches, cereal flour, modified starches, gums, proteins, and mixtures thereof to encapsulate essential oils, oleoresins, and mixtures. The composition is melted in the presence of 10% to 40% by weight of water and extruded under non-puffing conditions. The flavor agent forms a micro dispersion in the glasseous melt.
U.S. Pat. No. 5,972,395 discloses the use of a matrix composed of 15 to 40% of a high molecular weight carrier, preferably a maltodextrin and at least 40% of a low molecular weight carbohydrate, sugar polyol, or adipic acid. The matrix is extruded to yield a solid matrix characterized as a glass.
U.S. Pat. Nos. 5,087,461 and 5,009,900 disclose utilizing a composition consisting of a modified food starch, maltodextrin, polyol, and mono- and disaccharide components. The starch is a chemically-modified water-soluble starch and is used in the amount of 40 to 80% of the total mixture. The balance of the composition is comprised of 10 to 40% maltodextrin, 5 to 20% corn syrup solids or polydextrose, and 5 to 20% mono- or disaccharide. This matrix is said to balance processing response with glass matrix character.
U.S. Pat. No. 5,756,136 discloses the encapsulation of cinnamic aldehyde in a matrix containing at least 25% of a whey protein isolate. The resulting encapsulate exhibits a control release functionality and protection for yeast-leavened dough.
U.S. Pat. Nos. 6,652,895; 6,416,799; 6,187,351; 5,603,971; and 5,897,897 disclose the use of a series of extrusion matrix compositions. The use of water to plasticize the matrix in the extrusion process yields an encapsulated flavor matrix characterized by glass transition temperatures greater than 40° C. In U.S. Pat. No. 6,652,895, a composition containing a carboxylate or sulfate containing food polymer and the presence of calcium ions in the melt is disclosed. In U.S. Pat. No. 6,416,799, a composition containing a maltodextrin with buffering organic acid-acid salts is disclosed. In U.S. Pat. No. 6,187,351, a composition containing 2 to 45% of a food polymer, 25 to 80% of a maltodextrin, and 10 to 30% of a mono- or disaccharide or 24 D.E. to 42 D.E. corn syrup solids is disclosed. The matrix is dry blended, fed into the extruder with the required water plasticizer and flavor, and the resulting encapsulate is obtained as a glassy solid exhibiting a glass transition temperature greater than 40° C. The disclosed polymers include modified celluloses, high methoxy pectin, gum arabic (acacia), locust bean gum, guar gum, and lesser gums such as gum ghatti, gum tragacanth and gum karaya. Also disclosed are proteins such as gelatin and casein, microbial gums such as xanthan and gellan, pregelatinized starches in addition to other carbohydrate polymers such as inulins, beta-glucans and konjac flour.
U.S. Patent Application 2002/0189493 discloses the use of majority, single polymer component compositions with melt extrusion encapsulation. In one case, a matrix composed of a binary polymer composition selected from the group of gelatin, hydrolyzed gelatin, larch gum and gum arabic at 0 to 50% of the individual polymers is disclosed.
U.S. Patent Application 2002/0187223 teaches the use of prehydrated agar agar (at 1-7% levels) with other carriers which are mixed with a flavor, extruded and dried to form a glassy matrix encapsulating media.
U.S. Pat. No. 4,816,298 discloses the preparation of a cold-water dispersible granular composition comprising a plasticizer and thermally moldable polymers. The polymers are selected from the group of methyl cellulose, hydroxypropyl methylcellulose, carboxymethyl cellulose, and hydroxypropyl cellulose and are extruded at an elevated temperature with plasticizer to yield a cold-water dispersible matrix.
In a number of the cited patents which disclose melt extrusion, the matrix compositions were carefully defined to accommodate processing limitations of the extruder, as well as to generate a stable matrix in the glassy state characterized by a glass transition temperature of greater than 40° C. The cited patents describe liquid flavor, essential oils, oleoresins, processed flavors, medications, pesticides, and vitamins as encapsulates.
Formation of a matrix in the glassy state is of particular value for encapsulation of water-soluble flavorings and extracts. The role of water as a plasticizing agent conflicts with the desired results, because water has the effect of lowering the glass transition temperature (Tg) of the glassy matrix. In model studies of a number of food carbohydrate systems, the upper limit of water content is approximately 7 to 10 wt. % for lower molecular weight components such as mono- and disaccharides, maltodextrins, food polymers and combinations of these agents. At higher water contents, the Tg is lowered to the extent that the matrix is in the undesirable rubbery, plastic or fluid state at room temperatures.
In order to insure a higher Tg, several options are available. By limiting the class of encapsulate materials to lipophilic materials such as citrus oils, plasticizing moisture can be removed by a boil off process as described in U.S. Pat. Nos. 2,856,291; 2,809,895; 3,314,803; 3,704,137; and 4,707,367. Alternatively, the use of melt injection limits the flavoring agents to materials with lower vapor pressure which can be admixed to the composition before melting. Flavorings which are in the form of aqueous extracts, water, or alcohol-water solutions will result in a product with a Tg much below 25° C. leading to plastic flow and loss of volatiles upon storage.
Similarly, in U.S. Pat. Nos. 5,009,900 and 5,972,395, the flavorings are limited to those with limited volatility, and total moisture level in the product is less than 11% by weight. Many of the key top notes and unique flavor components of complex flavors have high vapor pressures at room temperature and are not easily encapsulated by such a process.
Matrix improvements for the continuous melt extrusion process are described in U.S. Pat. Nos. 6,652,895; 6,416,799; 6,187,351; 5,603,971; and 5,897,897. The use of modified starch and food polymers with low molecular weight carbohydrate plasticizers is detailed to yield encapsulates in a glassy matrix with a Tg greater than 40° C. However, with these matrices, the flavor loads are generally limited to 10 wt. % or less. Encapsulates described were medications, pesticides, vitamins, preservatives, and flavoring agents, wherein the flavoring agent is selected from the group consisting of natural extracts, oleoresins, essential oils, protein hydrolyzates, aqueous reaction flavors, compounded natural flavors, and artificial flavors.
Preparation of a solid in the glassy state is dependent upon both matrix composition and the process used to generate the encapsulating material. The advantages of retaining the glass form of the matrix include increased physical stability of the solid, reduced loss of incorporated volatiles, and reduction of deleterious intermolecular reactions and oxidation. A detailed discussion of the physical chemistry of water-food polymer interactions relating to the glassy state can be found in H. Levine and L. Slade, "Glass Transitions in Foods," in Physical Chemistry of Foods, H. Schwartzberg and R. Hartel, Eds., Marciel Dekker, New York, pp. 83-205, 1992; and in H. Levine and L. Slade, "Water as a Plasticizer: physico-chemical aspects of low-moisture polymeric systems," in Water Science Reviews, vol. 3, F. Franks, Ed. Cambridge University Press, London, pp. 79-185, 1988, which are incorporated herein by reference. The role of water as a plasticizer with food polymers, as well as the relationships between molecular compositions and dynamics of interactions between various components, are discussed in these references.
It is important to mention that melt extrusion is not a drying process. It generates glassy compositions by melting matrix components, followed by a quick cooling of the melt. Optionally, in-process or post-processing drying could be applied to further control moisture and other properties of the compositions. However, drying is not essential for the formation of glassy encapsulation compositions. Water or aqueous solutions used as a plasticizer are added in the amounts not preventing formation of a glassy matrix with the glass transition temperature above ambient temperature. In other words, quick cooling of the matrix makes it glassy without significant water evaporation. This distinguishes the melt extrusion process from spray-, drum-, or tray drying where a glassy matrix may be obtained mainly though evaporation of water from a slurry.
Spices and herbs in their original and ground powdered form possess unique flavor properties. More recently it has been recognized that spices and herbs contain potent antioxidants that may have protective properties for oils and flavors. The same antioxidants may be health beneficial. Thus, there remains a need for encapsulation compositions in which an encapsulate is encapsulated in an active carrier which is stable in the glassy state at ambient or slightly elevated temperatures and contains a significant amount of spices and herbs in addition to liquid or solid encapsulates. These active carriers can exhibit unique flavor interactions with encapsulates and modulate a flavor imparted by encapsulates. In turn, flavors may modulate flavor characteristics imparted by the active carrier and have an effect on bioavailability or other antioxidant or protective functions of spices and herbs. There is also a need to mask, modify or mitigate some of the intense background notes introduced by either spices, herbs or encapsulates. The glassy carriers can preserve, modulate and control release of encapsulates. There is also a need to preserve labile and sensitive flavors with natural antioxidants introduced by spices and herbs constituting a significant part of the active carrier.

This patent is subject to a terminal disclaimer.

Melt extrusion encapsulation of flavors and other encapsulates in a carrier containing spices and herbs


This invention relates to site-specific integration and expression of recombinant proteins in eukaryotic cells. In particular, the invention includes compositions and methods for improved expression of antibodies including bispecifc antibodies in eukaryotic cells, particularly Chinese hamster (Cricetulus griseus) cell lines, by employing an expression-enhancing locus.

Cellular expression systems aim to provide a reliable and efficient source for the manufacture of a given protein, whether for research or therapeutic use. Recombinant protein expression in mammalian cells is a preferred method for manufacturing therapeutic proteins due to, for example, the ability of mammalian expression systems to appropriately post-translationally modify recombinant proteins.
Despite the availability of various expression systems, the challenge of efficient gene transfer and stability of the integrated gene for expression of a recombinant protein still exists. For long-term expression of a target transgene, one consideration is minimal disruption of cellular genes to avoid changes in the phenotype of the cell line.
Engineering stable cell lines to accommodate multiple genes for expression, such as multiple antibody chains as in multispecific antibodies, is particularly challenging. Wide variations in expression levels of integrated genes may occur. Integrating additional genes may lead to greater variation in expression and instability due to the local genetic environment (i.e., position effects). Expression systems for the production of multispecific antigen-binding proteins often requires the expression of two or more different immunoglobulin chains intended to pair as a specific multimeric format, and can often weigh in favor of homodimer production, rather than the desired heterodimer or multimer combination. Accordingly, there is a need in the art for improved mammalian expression systems.

Compositions and methods for making antibodies based on use of an expression-enhancing locus


A CMOS inverter which comprises a series of connected p-channel and n-channel MOS FETs of which gate electrodes, drain contact electrodes, and voltage source lines are arranged on different insulation layers stacked on each other. The drain contact electrodes are formed by a conductor, including a silicide of high melting point metal, such as, tungsten or molybdenum. They are coated by an insulation layer over which the voltage source lines and signal lines for transferring output to a succeeding stage are arranged. By doing so, the device area is decreased, and the substrate can be reflowed to smooth the surface of the insulator so as to prevent disconnecting of the wirings.

This invention generally relates to a semiconductor integrated circuit. More particularly, this invention relates to a circuit having complementary metal oxide semiconductor type inverters.
Metal oxide semiconductor (MOS) type field effect transistors (FETs) are widely used in integrated circuits (ICs), especially complementary MOS (CMOS) FETs which are used for inverters having various circuits, such as a peripheral circuit of a dynamic random access memory (DRAM) device.
FIG. 1(a) shows a circuit diagram of a double stage inverter circuit. The first stage is composed of a p channel FET Tp1, and an n channel FET Tn1. The FETs are connected in series between a positive voltage source line Vcc1 and a negative voltage source line Vss1. The gate electrodes of these transistors are connected to each other, and G1 a first junction point of these gates is connected to an input terminal Din. The source electrodes Sp and Sn of these transistors are respectively connected to the Vcc1 or Vss1, while the drain electrodes Dp and Dn of these FETs are connected to each other, and outputs an inverted signal to a first output signal line N1 which feeds the inverted signal to the second stage inverter. The second stage inverter is also composed of a p channel FET Tp2 and an n channel FET Tn2. These transistors are connected similarly to the first inverter. These transistors receive the inverted signal from the first signal line N1 at a second junction point G2, and output the signal to a second output signal line N2 which is connected to an output terminal Dout. The second voltage source line Vss1 is usually grounded.
FIG. 1(b) is a schematic plan view illustrating an exemplary arrangement of elemental devices on an IC chip showing a portion of a double stage inverter circuit, as shown in FIG. 1(a). The p-channel FETs Tp1, Tp2 and the n-channel FETs Tn1, Tn2 are formed in a semiconductor substrate. These FETs are separated from each other by a field oxide layer and coated by a gate oxide layer. The insulation layers are not shown in FIG. 1(b), but they can be considered to be coating for the entire surface of the substrate. The gate electrodes G1 and G2 are usually formed with a doped polysilicon layer deposited on the gate oxide layer. The entire surface of the substrate is further coated with an insulation layer, such as, silicon dioxide (SiO.sub.2) which will be called first insulation layer hereinafter. The first insulation layer is also not shown in FIG. 1(b) because it is coating for the entire surface of the substrate. The voltage source lines Vcc1, Vss1 and the signal lines N0, N1, N2 are formed over the first insulation layer by patterning an aluminum film, for example. They are respectively identified in FIG. 1(b) with a double dot chain line, a single dot chain line and broken lines. These wiring patterns are connected to corresponding electrodes Sp, Sn, Dp, Dn, G1, G2 through respective contact holes formed through the insulation layers. These contact holes are identified by cross hatched areas in FIG. 1(b).
The configurations inverter circuits cause several problems when packing density of the elemental devices in the IC becomes high. Generally, the voltage source lines Vcc1 and Vss1 are required to be wider compared to other wiring lines, such as, G1, G2 or N0, N1, N2 because voltage source lines have to carry a larger current than those of other wiring lines. If the aluminum wiring lines are made too narrow, the current density in the wiring line increases which causes electro-migration of aluminum, and the reliability of the device decreases; thereby, reducing the size of the device. Further, as can be seen in FIG. 1(b), the voltage source lines Vcc1, Vss1 and the signal lines N0, N1, N2 are formed on a same layer (the first insulation layer) with the same aluminum film. Accordingly, the Vcc1 or Vss1 lines must be arranged in an outside area of the device, and extended branch members B toward the inside of the device in order to contact with respective electrodes Sp or Sn since the voltage source lines Vcc1, Vss1 have to be separated from the signal lines N0, N1, N2 which are arranged at the center part of the device. Accordingly, a limitation on the design to reduce the size of the device size is set.

Semiconductor integrated circuit having CMOS inverters


Systems and methods for whirl mitigation in an aircraft braking system are provided. For example, an apparatus is provided comprising a brake disk stack including a torque tube having a first axial end and a second axial end, a back leg near a first axial end of the torque tube, and a circumferentially disposed spline extending from the back leg towards the second axial end of the torque tube.

Aircraft brakes tend to vibrate during use. Aircraft brakes may exhibit the whirl mode of vibration ("whirl") and/or the squeal mode of vibration ("squeal"). Squeal may be understood as a torsional motion of the non-rotating brake parts about the axle. Whirl may be understood as a wobble outside the rotational plane between a torque plate and a backleg. Whirl typically occurs in the range of about 200 Hz to about 500 Hz. While it is desirable to mitigate both squeal and whirl, whirl is potentially more damaging than squeal. Thus, there exists a need for systems and methods that assist in whirl mitigation.

Systems and methods for brake whirl mitigation


A radially symmetrical optoelectric module includes a receptacle assembly with a symmetrical tubular ferrule and a first lens. The ferrule defines an axial opening extending along an optical axis. The ferrule is formed radially symmetrical about the optical axis with the first lens engaged in the ferrule along the optical axis. One end of the ferrule is formed to receive an end of an optical fiber such that the end is positioned along the optical axis and adjacent the first lens. An optoelectric package includes an optoelectric device and a second lens. The second lens is positioned adjacent the optoelectric device and positioned along the optical axis so that light traveling along the optical axis appears at the optoelectric device and passes through the second lens.

This invention relates to optical-to-electrical and electrical-to-optical modules.
More particularly, the present invention relates to optical-to-electrical and electrical-to-optical modules that are radially symmetrical about a longitudinal axis.
And more specifically the present invention pertains to optical-to-electrical and electrical-to-optical modules that incorporate a lens system, along with the radially symmetrical features that compensate for temperature changes.
In optical-to-electrical and electrical-to-optical (hereinafter xe2x80x9coptoelectricxe2x80x9d) modules used in the various communications fields, one of the problems that must be solved is the efficient transmission of light between a light generating device and an optical fiber or, alternatively, the transmission of light from the optical fiber to a light receiving device without being affected by temperature changes and the like. Here, it will be understood by those skilled in the art that the term xe2x80x9clightxe2x80x9d is a generic term that includes any electromagnetic radiation that can be modulated and transmitted by optical fibers or other optical transmission lines.
Here it will be understood that the optoelectric modules are used to communicate between an optical fiber and an optoelectric device, such as a light source (e.g. a laser, light emitting diode, etc.) generally referred to as a transmission module, or between an optical fiber and a light receiving device (e.g. a photodiode, PIN diode, PN diode, etc.) generally referred to as a receiving module. In this disclosure both modules are referred to generically as optoelectric modules.
Generally, one of the problems with optoelectric modules is the amount of time and effort required in the fabrication and assembly. Another problem that arises is that much of the time and effort in assembly and mounting is applied in alignment of the various components so that light generated by, for example a laser, reaches the core of an optical fiber and light emanating from an optical fiber must be directed onto a photo diode or the like. After substantial time is expended in the original alignment procedures, temperature changes and the like during operation can substantially change the alignment and cause substantial changes in the amount of light being usefully applied. These changes can substantially affect the continued operation of the modules.
It would be highly advantageous, therefore, to remedy the foregoing and other deficiencies inherent in the prior art.
Accordingly, it is an object the present invention to provide new and improved radially symmetrical optoelectric modules.
Another object of the present invention is to provide new and improved radially symmetrical optoelectric modules that further incorporate a novel lens systems so that expansion and/or contraction during changes in temperature does not affect alignment.
Another object of the present invention is to provide new and improved radially symmetrical optoelectric modules that are easily aligned and assembled.
Another object of the present invention is to provide new and improved radially symmetrical optoelectric modules that remain aligned during changes in operating temperature.
And another object of the present invention is to provide new and improved radially symmetrical optoelectric modules that improve the efficiency of optical systems.
Still another object of the present invention is to provide new and improved radially symmetrical optoelectric modules that allow the use of a variety of components and component materials.
Briefly, to achieve the desired objects of the present invention in accordance with a preferred embodiment thereof, provided is a radially symmetrical optoelectric module including a symmetrical ferrule defining an axial opening extending along an optical axis and having first and second ends positioned along the optical axis. The ferrule is formed radially symmetrical about the optical axis with a lens assembly engaged in the ferrule along the optical axis. A first end of the ferrule is formed to receive an optical fiber such that an end of the optical fiber is positioned along the optical axis and adjacent the lens assembly and light passing through the optical fiber is acted upon by the lens assembly and an optoelectric device is affixed to the second end of the ferrule so that light traveling along the optical axis appears at the optoelectric device.
In a preferred embodiment, the radially symmetrical optoelectric module includes a receptacle assembly with a symmetrical ferrule and a first lens. The ferrule defines an axial opening extending along an optical axis and has first and second ends positioned along the optical axis. The ferrule is formed radially symmetrical about the optical axis and the first lens is engaged in the ferrule along the optical axis. The first end of the ferrule is formed to receive an optical fiber such that an end of the optical fiber is positioned along the optical axis and adjacent the first lens with light passing through the optical fiber being acted upon by the first lens. An optoelectric package includes an optoelectric device and a second lens positioned adjacent the optoelectric device, the second lens is mounted along the optical axis by the optoelectric package. The optoelectric package is affixed to the second end of the ferrule so that light traveling along the optical axis appears at the optoelectric device and passes through the second lens. Because of the xe2x80x9ctwo lens systemxe2x80x9d axial spacing of the structural components is not critical and because of the combination of radial symmetry and the two lenses, the module expands and contracts equally in all directions during changes in temperature so that alignment is not affected and the module provides a constant output under varying conditions.

Radially symmetrical optoelectric module


A method, apparatus and system is provided for assessing risk for well completion, comprising: obtaining, using an input interface, a Below Rotary Table hours and a plurality of well-field parameters for one or more planned runs, determining, using at least one processor, one or more non-productive time values that correspond to the one or more planned runs based upon the well-field parameters, developing, using at least one processor, a non-productive time distribution and a Below Rotary Table distribution via one or more Monte Carlo trials; and outputting, using a graphic display, a risk transfer model results based on a total BRT hours from the Below Rotary Table and the non-productive time distribution produced from the one or more Monte Carlo trials.

In the oil and gas industry, drilling and completing hydrocarbon wells involve a complex process of drilling and other operations. When completing a hydrocarbon well, drilling operators typically run a variety of downhole monitoring equipment within the wellbore to improve well completion effectiveness and profitably. Often times when completing wells, drilling operators are bound to strict timelines and may gauge their performance using variety of performance metrics. In many instances, to remain profitable, the drilling operators may need to exceed the performance metrics and/or complete the wells before the designed timeline. For instance, drilling operators may be evaluated on the performance metric nonproductive time or NPT. In certain instances, if the total NPT time for completing a well exceeds a specified threshold, the drilling operator may be required to pay a penalty equivalent to the damages caused by the excessive NPT. Alternatively, for the same well completion job, the drilling operator may receive bonus compensation if the total NPT time falls under the specified threshold. As such, numerous innovations and improvements are needed to accurately gauge NPT and/or other performance parameters and assess well completion risk.

Method of predicting drilling and well operation

THE HARTFORD STEAM BOILER INSPECTION AND INSURANCE COMPANY


A software layer is disposed between an application and a driver. In use, the software layer is adapted to receive an object from the application intended to be rendered by a first graphics processor. Such software layer, in turn, routes the object to a second graphics processor, based on a policy.

In some graphics environments, more than one graphics processor is available for graphics processing purposes. For example, a first graphics processor may be capable of providing a limited amount of graphics processing capabilities as well as using system memory, as opposed to its own dedicated memory. Still yet, a second graphics processor may be provided with more advanced graphics processing capabilities as well as its own dedicated memory. Of course, such additional processing capabilities generally come at increased cost in terms of power, etc. There may also be secondary sources for an increase; for example, greater memory usage, data bus activity (e.g. PCI Express), or transistor leakage (which increases with increased overall silicon area), etc.
There is a continuing need for addressing the various trade-offs (e.g. performance vs. power, etc.) associated with such multi-graphics processor systems.

System, method, and computer program product for policy-based routing of objects in a multi-graphics processor environment


A method of manufacturing a flexible amorphous silicon solar cell includes the steps of: a) coating a PI varnish on a glass substrate; b) imidizing the PI varnish film; c) vacuum-depositing a metal film on the PI film; d) vacuum-depositing an amorphous silicon film on the metal film; e) vacuum-depositing a transparent conducting film on the amorphous silicon film; and f) separating the PI film from the glass substrate. The method also provides for preparing the PI varnish by the steps of: 1) preparing a mixed solution of 60-100% by weight aprotic solvent, and 0-40% by weight aromatic solvent; 2) adding into the mixed solution in a mole ratio of 1:9 two aromatic diamines; and 3) further adding in the mixed solution in a mole ratio of 1:5 two aromatic dianhydrides.

The present invention relates to a manufacturing method of a flexible amorphous silicon solar cell.
Solar cell is a new pollution-free energy source with applications and market demand thereof increasing steadily. It finds applications in consumer electronics products as well as in power system, and has good prospects of being one of the major energy sources. Flexible amorphous silicon solar cells are fabricated by depositing amorphous silicon, metallic and transparent conductive oxide films on a flexible substrate with the desirable features of light weight, thin thickness, flexibility, portability and nonfracture, and can be more useful than the traditional glass-substrate amorphous silicon solar cells.
There are two main types of flexible amorphous silicon solar cells, namely:
(1) The ones with metal substrate
Presently, the substrate is made of stainless steel on which there are sequentially grown metallic, amorphous silicon, and transparent conductive oxide (TCO) films, as typified by the products of ECD, Sovonics Solar System companies of the U.S.
(2) The ones having the substrate made of a polymer material
Two kinds of polymer films are used, including films of polymer materials with good transparency and those with poor transparency. The former has a very high transmission in the visible light range so that there can be sequentially grown thereon transparent conductive oxide, amorphous silicon and metal films to form a structure the same as that of the glass-substrate solar cell purchased from Sanyo Electric Co. Ltd. Amorphous silicon solar cells with the substrate made of a polymer material with poor transparency have the same structure as that of metal substrate amorphous silicon solar cells. On the amorphous silicon solar cells, there are sequentially grown metal amorphous silicon, and transparent conductive oxide films, as typified by the solar cells developed by the Iowa Thin Film Technology Inc. of the U.S., and the Sanyo Electric Co., Ltd. of Japan.
Compared with polymer substrate solar cells, metal substrate solar cells are heavy and not easily rollable. This is because it is not easy to make metal substrate thin and rollable enough. The flexible solar cells are required to be light-weight, thin as well as flexible. Although European Patent Application No. 0,109,976 filed by Sovonics Solar System has disclosed to make a very thin, light weight and flexible amorphous silicon solar cell on a very thin metal substrate (<50.mu.m), or by etching away the metal substrate after the cell is produced, the manufacturing procedure thereof is too complicated, and the cost is too high. Solar cells with polymer substrate will be more flexible, lighter in weight, and thinner than those with metal substrate.
The polymer films suitable for being used as the substrate of solar cells should have the following characteristics:(1) good heat stability; (2) good mechanical strength; (3) surface smoothness and thickness uniformity; (4) high purity (low ion content) to avoid gas release in a high vacuum, and (5) good weatherability to avoid degrading after long time exposure to sunlight. Therefore, developing a suitable polymer material for the substrate would be one of the key techniques. Besides, the choice of the right technology for depositing the films on polymer substrate in vacuum is also critical because of the significant thermal expansion coefficient of polymer films. The right technology would ensure that the polymer substrate would not be deformed or warped, and the films deposited thereon would be even in thickness and would not be easily stripped off or cracked.
The types of polymer substrates for polymer film solar cells include:
1) polyimide (PI)-film substrate:
Most of the PI films used are those marketed under the trademark of "Kapton" from Du Pont of the U.S., having primary constituents of pyromellitic dianhydride (PMDA) and oxydianiline (ODA), and with desirable characteristics in heat resistance, mechanical strength, electrical insulation, radiation-shielding, and chemical-resistance. However, its coefficient of thermal expansion (TCE) is relatively high (4.0-5.0.times.10.sup.-5 cm/cm.degree. C.) and the PI film is very soft, and when aluminum (TCE:1.3.times.10.sup.-5 cm/cm.degree. C.), chromium (TCE:6.times.10.sup.-6 cm/cm.degree. C.), and amorphous silicon (TCE:1.9-4.times.10.sup.-6 cm/cm.degree. C.) films are deposited on the PI film in vacuum (with operation temperature up to 250.degree. C.), there would be a stress mismatch between the PI film and the films deposited on it, resulting in the deposited films being easily stripped off and cracked, and uneven in thickness.
To alleviate the problems of warping and excessive thermal expansion coefficent of PI films used as substrate, some people tried to add a supporting layer under the PI film as disclosed in U.S. Pat. No. 4,514,583; Japan kokai Nos. 60-79779 and 60-66869; and European Patent Application No. 0 ,189,976 filed by Sovonics Solar System. This supporting layer is mostly a thin film of a metal. Some use fabrics or polymer material. The European Patent Application No. 0,189,796, filed by Sovonics Solar System, uses a very thin metal film on which a PI film is applied. When the films are deposited on the substrate, the supporting layer is selectively etched to get the flexible solar cell. Alternatively, the metal film can be retained as a part of the substrate. The method according to the Sovonics Solar System patent is too complicated. The composite substrate comprising a thin metal supporting layer and a PI film is still too soft, and it's thermal expansion coefficient would still be excessive, and the substrate would be warped during the a-Si:h deposition.
Supporting layer made of fabrics or glass fiber fabric would not make a good substrate since it has a surface having a roughness possibly amounting to several .mu.m to several ten's .mu.m and the PI film applied thereon will also be uneven.
2) Polyether sulfone (PES) film-substrate:
PES has a glass transition temperature of 225.degree. C. and will easily release gas in a vacuum. Thus PES substrate (TCE) has poor characteristics and is not suitable for high efficiency device. The TCE of PES is 5.5.times.10.sup.-5 cm/cm.degree. C. which is even larger than that of PI and presents more difficulty in reaching the stress match between PES film and metal, amorphous silicon films and indium tin oxide (ITO, a transparent electrode material).
3) PI/MeO/PI/MeO (wherein MeO means metal oxide) multi-layer film substrate:
Laminated substrate comprising alternating PI and MeO layers would ameliorate the softness and reduce the TCE of PI substrate. However, the lamination process is too complicated. Until now, solar cells with polymer substrate and metal substrate are mostly fabricated by a roll-to-roll process to deposit the various layers on the flexible substrate in vacuum. The equipment, such as the thermal evaporator sputter or the E-Beam gun evaporator, required for depositing the metal or the transparent conductive oxide films on substrate, although having been commercialized, is very expensive. And it is complicated and difficult to adapt to roll-to-roll plasma-enhanced chemical vapor deposition (PECVD), also called glow discharge chemical vapor deposition (GD-CVD) required for depositing amorphous silicon films. Presently, no commercialized PECVD equipment available is used for the roll-to-roll operation. Users must develop the equipment required by themselves. To enhance the efficiency of the solar cells, the N, I, P layers of amorphous silicon would have to be deposited separately in three different reaction chambers (i.e. in a multichamber PECVD equipment) to avoid contaminating each other. It's very difficult to make such solar cells by the roll-to-roll process, which is still under studies now.
Therefore, the following drawbacks exist in depositing the films of polymer solar cells by roll-to-roll process: 1) The available equipment for the glass substrate solar cells cannot be utilized, and the required new equipment is not available; 2) Because the film deposition occurs in a large area, it is difficult to maintain the required flatness of the polymer substrate in this large area film deposition process. It is also difficult to control the deformation of the substrate caused by heating, resulting in expansional deformation of the films deposited and poor quality; 3) It is difficult to perform multichamber with PECVD to increase the efficiency of polymer solar cells; 4) The equipment is expensive, and consequently the production cost is high.
The kapton from Du Pont, as mentioned earlier, has a high thermal expansion coefficient and has strong adhesion between the glass substrate and the PI film deposited thereon, rendering it difficult to have the PI peeled off the substrate.
It is therefore attempted by the Applicant to deal with the above shortcomings encountered by the prior art.

Method for manufacturing flexible amorphous silicon solar cell

Industrial Technology Research Institute


A production line for manufacturing automobiles, for example, has a plurality of self-propelled carriages for carrying workpieces respectively thereon, the self-propelled carriages having respective first emergency shutdown circuits, and a plurality of automatic machines for processing the workpieces on the self-propelled carriages, respectively, the automatic machines having respective second emergency shutdown circuits, respectively. When one of the self-propelled carriage malfunctions, the first emergency circuit thereon is energized to interrupt movement of the self-propelled carriage along the production line, and operation of the automatic machine which processes the work-piece on the stopped self-propelled carriage is stopped in response to a signal which energizes the first emergency shutdown means on the self-propelled carriage. Alternatively, the second emergency shutdown circuit on one of the automatic machines is energized to interrupt operation of the automatic machine, and movement of the malfunctioning self-propelled carriage which carries the workpiece processed by stopped automatic machine is stopped in response to a signal which energizes the second emergency shutdown circuit.

The present invention relates to a method of and an apparatus for stopping the operation of a production line in case of an emergency, and more particularly to a method of and an apparatus for localized emergency shutdown of a production line including self-propelled carriages for transferring workpieces along a power feed line and automatic machines disposed in respective working zones or work stations along the production line for assembling and machining the workpieces, the method and apparatus being capable of stopping the operation of a self-propelled carriage and an automatic machine in case of emergency only in the working zone which is subjected to an operation failure.
The automobile industry has one of the most advanced automatic production facilities. The automobile production lines are combined with various industrial robots which replace manual labor and effect various operations such as assembling, coating, welding, and other processes.
The automated production lines are also associated with automated workpiece feed means. One recent example of such automatic workpiece feed means is the use of self-propelled carriages instead of conventional conveyor lines. Self-propelled carriages independently run along desired tracks in a factory. They can more easily adapt themselves to modified track layouts than the conveyor lines, and do not take up a large space. Therefore, the space available in the factory can be utilized effectively.
Self-propelled carriages run to transfer workpieces from one station to another along a production line while being supplied with electric power from a power feed line extending along the production line.
Heretofore, the power feed line is arranged to extend through all production stations or working zones along the production lines. If an unexpected serious trouble occurs in one production station, then the power feed line has to be cut off to stop the operation of the self-propelled carriage and the automatic machine or robot in the faulty production station, and hence all the production stations are shut off of necessity. Once the automobile assembly line is shut off to stop the manufacturing operation, it takes a considerable time to restore the production line back to normal operation. Such assembly line shutdown results in quite a large loss of money since each automobile product would otherwise be completed very rapidly in a matter of seconds.
Japanese Laid-Open Utility Model Publication No. 61-154128 discloses a system in which a power feed line extending along a production line is divided into segments associated with respective working zones and the electric power supplies for the power feed line segments can independently be turned on and off to prevent the entire production line from being shut off.
However, since production lines have a large number of working zones or production stations, it is time-consuming and laborious to install such power feed line segments in the respective working zone and control units for independently turning on and off the power supplies for each power feed line segments. Therefore, the cost of such independently controllable power line segments is very high.

Method of and apparatus for emergency shutdown of production line


This invention is to prevent coloring or clouding of the molded article, and also to prevent fusion between the glass blank and the mold member and crack formation in the molded article.. The glass blank is provided with the surface layer containing a lower content in water-soluble components than in the core part of the glass base, and a hydrocarbon coating layer formed on the layer. The blank is then press molded.

1. Field of the Invention
The present invention relates to a glass blank employed as a molding material in the press molding of an optical element such as a lens, and more particularly to a glass blank capable of preventing a reaction with the mold member upon press molding, also reducing the adhesive force and the frictional force, thereby avoiding fusion and crack formation in the course of cooling and obtaining a satisfactory optical element, and also to a method for producing an optical element utilizing the glass blank.
2. Related Background Art
For obtaining a satisfactory molded product from the reheating and pressing of glass, it has been a major problem to avoid fusion between the molding glass and the mold member. For this purpose there have been proposed various technologies in the improvement of the mold member, and improvements in the molding material are recently starting to be proposed for preventing the type of fusion mentioned above. Among such proposals for the improvement of the molding material, Japanese Patent Publication Nos. 2-1778, 2-1779, 2-1780 and 61-29890 disclose providing the surface of a glass base with a coating of glass having a higher glass transition point than that of the glass base, a coating of silicon oxide or of carbon. Also, Japanese Patent Laid-open Application No. 1-264937 discloses providing the surface of a glass base with a thin organic layer. Also, the Japanese Patent Laid-open Application No. 62-207728 discloses removing evaporable components on the surface with an acid.
These improvements are effective for avoiding fusion of the glass to the mold member, but the methods disclosed in the above-mentioned references are associated with the following drawbacks:
(a) When the surface of the glass base is provided with a coating of glass having a higher glass transition point than that of the glass base, the glass coating layer is cracked by the molding pressure, and the glass base oozes through the crack causing local clouding on the surface or local fusion of the glass base to the mold member. Also, the adhesive force and the frictional force between the glass blank and the mold member may become large in the course of cooling, eventually causing a crack in the glass base;
(b) When the surface of the glass base is given a coating of silicon oxide, there will be encountered difficulties similar to those in case (a). Particularly, cracks easily occur in the course of cooling, because silicon oxide strongly stickes to with the mold member. The coating tends to crack in the heating stage, because the thermal expansion coefficient of silicon oxide is significantly lower than that of the ordinary optical glass constituting the glass base;
(c) If the surface of the glass base is given an unnecessarily thick carbon coating, the carbon, being a reducing agent, reacts with oxygen in the glass, thus reducing the glass components and giving a brown color thereto. Particularly, if lead-containing glass is used as a glass base, PbO therein is reduced, so that the glass is colored conspicuously and has a lowered transmittance;
(d) When the surface of the glass base is given a thin organic layer, the layer is decomposed upon heating, eventually generating a corrosive gas (such as chlorine or fluorine), thereby contaminating the press molding apparatus and affecting the life of the apparatus including the mold member. Also, the surface precision of the molding apparatus may be deteriorated because the decomposition occurs locally at random;
(e) In some optical glasses, when immersed in acid, not only the volatile components but also the glass itself are dissolved, thus the acid treatment is not usable in such a case.
For avoiding these drawbacks, Japanese Patent Application No. 2-187148 proposes a glass blank having a hydrocarbon coating on glass. According to this proposal, the hydrocarbon coating contains a larger amount of CH.sub.2 in comparison with the carbon coating of a same thickness, thereby being superior in preventing fusion and crack formation, without excessive deterioration of the transmittance of the glass blank.
However, this proposal is still associated with a drawback in that the molded article becomes clouded, though slightly, by the reaction of easily-reactive components in the glass blank, particularly alkali metal oxides and boric, acid, with the hydrocarbon coating.

Method for producing optical element by press molding a blank having a component removed layer and a hydrocarbon coating


The invention relates to a vacuum sewage system, which includes a sanitary unit, such as a toilet unit, vacuum sewer piping (200) connected to the sanitary unit, a discharge valve between the sanitary unit and the vacuum sewer piping, and a vacuum generating device for generating vacuum in the vacuum sewer piping. The system comprises an on-line separator device (1) in the vacuum sewer piping (200, 201) and a first pump means (2) and a second pump means (3) connected in parallel with the on-line separator device (1). The first pump means (2) is a vacuum pump for generating vacuum in the vacuum sewer piping (200, 201) and for evacuating air from the sewage flow flowing into the on-line separator device (1) and the second pump means (3) is arranged for pumping mainly sewage from the sewage flow flowing into the on-line separator device (1).

Vacuum sewage systems, particularly vacuum toilet systems, are well known. At a first stage of development a vacuum sewage system typically comprised a large volume collecting tank, in which system the tank is maintained under vacuum in order to provide vacuum for the vacuum sewer piping. Vacuum is maintained in the large volume collecting tank by a separate vacuum pump. The sewage is emptied from the collecting tank by a sewage pump connected to the bottom of the collecting tank. Due to the large volume collecting tank, such systems require a lot of space, which normally is not available in e.g. trains, marine vessels and aircraft. An example of such a solution is disclosed e.g. in EP 0 330 490.
At a later stage, an ejector based system came along, in which sewage is circulated from a large volume collecting tank to a liquid jet pump opening into the same collecting tank. The liquid jet pump has an inlet connected to vacuum sewer piping and further to sanitary units, such as toilets. The sewage is circulated through the liquid jet pump, whereby the liquid jet pump generates a vacuum towards the vacuum sewer piping for drawing sewage from the toilets into the collecting tank. This solution requires a lot of space. Further, it has a low degree of efficiency. Such a solution is known e.g. from EP 0 653 524.
Other developments include a liquid ring pump that is connected to a large volume collecting tank, whereby vacuum is generated and sewage is pumped by the same pump in an alternating manner, e.g. EP 0 287 350.
Another single pump solution is disclosed in EP 0 644 299. This solution comprises a moisture protected dry rotary vane pump, which generates vacuum in a large volume collecting tank. This tank is emptied by reversing the pump function, so that the pressure side of the pump is connected to the large volume collecting tank for emptying the same by forcing out the sewage to another location by pressurized air. This solution also requires a large space and furthermore the pump is very vulnerable to any humidity, thus requiring intricate control mechanisms.
On-line systems provided with liquid ring pumps generating vacuum and pumping sewage directly from the vacuum sewer piping are also known and are disclosed e.g. in EP 0 333 045 and EP 0 454 794. A further on-line solution is described e.g. in EP 1 172 492. Such on-line systems deploy one single pump which generates vacuum and sucks sewage at the same time. These solutions represent attempts to reduce space requirement by eliminating the intermediate large volume collecting tank, i.e. a tank located between the pump and the vacuum sewer piping,
The latter solutions with on-line pumps having the dual duty of generating vacuum by sucking air and simultaneously sucking sewage are, however, not very efficient. Further, they are apt to functional disturbances. The pumps used in this context are designed either for pumping air or pumping liquid, whereby the transport of both air and liquid generally is not very successful.
This is due to the typical transport function of a vacuum sewage system, particularly a vacuum toilet system, where sewage is transported through the vacuum sewer piping in slugs with intermediate large volumes of air forming a non-homogenous sewage flow.
When a vacuum toilet is flushed by activating the flush function, the discharge valve between the vacuum toilet bowl and the vacuum sewer piping is opened, and the vacuum prevailing in the vacuum sewer piping draws out the sewage and flush water from the toilet into the vacuum sewer piping. Only a small amount of flush water is needed, due to the strong suction effect of the vacuum sewer piping and the atmospheric pressure prevailing in (and around) the vacuum toilet bowl. The amount of sewage and flush water is typically about 2 liters.
Consequently, there is a pressure difference, i.e. atmospheric pressure on the toilet bowl side of the sewage and flush water and vacuum on the vacuum sewer piping side of the sewage and flush water, when the discharge valve opens. The transport of sewage and flush water takes place due to this pressure difference, whereby the sewage and flush water forms a discrete slug followed by a large amount of air, e.g. about 2 liters of sewage and flush water followed by about 60 liters of air, i.e. a sewage and flush water in a ratio of about 1:30 to air. A large amount of air is sucked or forced into the vacuum sewer piping since the discharge valve remains open for a certain period of time.
Vacuum sewer piping generally is of a relatively small diameter which helps to keep up the formation of the slugs, which again is necessary for maintaining the pressure difference (lower pressure in front and higher pressure behind the discrete slugs) necessary for transport. During the transport through the vacuum sewer piping, the slugs are affected by gravity and flatten out after some time in horizontally arranged piping. This equalizes the pressure, whereby the necessary pressure difference described above before and after the discrete slugs is abolished. In order to re-establish the pressure difference for sewage transport, the vacuum sewer piping is provided with low points or pockets, in which the sewage collects so that the discrete slugs are formed again.
Such a train of discrete slugs and air, especially in a ratio of about 1:30, which forms the sewage flow in a vacuum sewage system, is difficult to pump with high efficiency.


The present invention is directed to a method of producing a sintered hard metal having a diamond film wherein a gas that is obtained by activating a raw material gas containing 2 to 60 mol % of carbon monoxide and hydrogen gas is brought in contact with a sintered hard metal to form a diamond film, thereby a diamond film can be formed on said sintered hard metal with the adhesion of the diamond excellent.

(1) Field of the Invention
This invention relates to a method of producing a sintered hard metal with a diamond film, and more particularly to a method of producing a sintered hard metal with a diamond film suitable for, for example, various cutting tools such as bits, end mils, drills, and cutters, draw dies, blanking dies, abrasion resistant machine parts, and the like.
(2) Description of the Related Art
Conventionally, in the field of various cutting tools such as bits, end mils, and cutters, since cutting tools excellent abrasion resistance can be obtained by using a diamond film as a protective film for cutting tools made of a sintered hard metal, the demand for cutting tools made of a sintered hard metal on which a diamond film is formed is increasing.
Conventionally, as methods of forming a diamond film on a sintered hard metal have been suggested, for example, a method wherein, prior to the formation of a diamond film, a sintered hard metal is subjected to ion etching treatment thereby activating the surface of the sintered hard metal, and then the sintered hard metal is contacted with an activated raw material gas (see Japanese Laid-Open Patent Application No. 204695/1985), and a method wherein prior to the formation of a diamond film on a substrate of a cermet, the cermet is etched with an acid solution to remove the bonding phase of the surface, and then the cermet is contacted with an activated raw material gas (see Japanese Laid-Open Patent Application No. 52363/1986).
However, the cutting tools of a sintered hard metal formed with a diamond film that are obtained by these methods still are accompanied by such problems that the cutting edge is still abraded, that chipping (breaking part of the cutting edge) will occur, and that it is still hardly said that the adhesion of the diamond film is satisfactory.
Thus, generally the adhesion between the surface of a sintered hard metal and a diamond film is poor.
Therefore, in order to improve the adhesion between the surface of a sintered hard metal and diamond, techniques for forming an intermediate layer between a sintered hard metal and a diamond thin film are developed.
For example, Japanese Laid-Open Patent Application No. 126972/1983 discloses a method wherein after an intermediate layer made of one or more compounds selected from a carbide, a nitride, a boride, and an oxide of a metal of Groups IVa, Va, and VIa of the periodic table is first formed on the surface of a sintered hard metal, a diamond thin film is formed on the intermediate layer.
Also, Japanese Laid-Open Patent Application No. 159981/1984 discloses a tool that includes on a metal such as W, Nb, Ta, V, Cr, and Hf a diamond thin film formed by the CVD method or the like.
However, in either of the above Patent Applications, since the thin film is formed stepwise by forming first an intermediate layer and then the diamond thin film, it is hardly said that the adhesion between the sintered hard metal and the diamond thin film has been improved sufficiently enough to the practical level although the methods are allegedly intended to improve the adhesion.
Further, as a tool member coated with artificial diamond, a tool member coated with artificial diamond is suggested wherein at least the tool working surface of a cermet substrate member is coated with an artificial diamond film having an average layer thickness of 1 to 1.2 .mu.m formed by an artificial diamond deposition formation process via a deposited layer having an average layer thickness of 0.05 to 1.2 .mu.m made of any one of W, Mo, and Nb and their alloys [see Japanese Patent Publication No. 15347/1988 (Japanese Laid-Open Patent Application No. 208473/1985)].
However, since, in the method disclosed in the Japanese Patent Publication mentioned above, the composition of the reactant mixed gas for the formation of diamond is 1 vol. % or below, the deposited metal layer is not effectively carbonized. Therefore, the adhesion between the diamond layer and the cermet substrate member is accordingly poor.

Method of producing sintered hard metal with diamond film


Provided is a supported catalyst for producing carbon nanotubes with a large specific surface area. The supported catalyst enables the production of carbon nanotubes with a large specific surface area in high yield. Therefore, the catalyst can be used in various fields. Also provided are carbon nanotubes produced using the supported catalyst.

1. Field of the Invention
The present invention relates to a catalyst for producing carbon nanotubes, and more particularly to a catalyst for producing carbon nanotubes with a large specific surface area and carbon nanotubes produced using the catalyst.
2. Description of the Related Art
Carbon nanostructures (CNSs) refer collectively to nano-sized carbon structures having various shapes, such as nanotubes, nanohairs, fullerenes, nanocones, nanohorns, and nanorods. Carbon nanostructures can be widely utilized in a variety of technological applications because they possess excellent characteristics.
Particularly, carbon nanotubes (CNTs) are tubular materials consisting of carbon atoms arranged in a hexagonal pattern and have a diameter of approximately 1 to 100 nm. CNTs exhibit insulating, conducting or semiconducting properties depending on their inherent chirality. CNTs have a structure in which carbon atoms are strongly covalently bonded to each other. Due to this structure, CNTs have a tensile strength approximately 100 times that of steel, are highly flexible and elastic, and are chemically stable.
CNTs are divided into three types: single-walled CNTs (SWCNTs) consisting of a single sheet and having a diameter of about 1 nm; double-walled CNTs (DWCNTs) consisting of two sheets and having a diameter of about 1.4 to about 3 nm; and multi-walled CNTs (MWCNTs) consisting of three or more sheets and having a diameter of about 5 to about 100 nm.
CNTs are being investigated for their commercialization and application in various industrial fields, for example, aerospace, fuel cell, composite material, biotechnology, pharmaceutical, electrical/electronic, and semiconductor industries, due to their high chemical stability, flexibility and elasticity. However, CNTs have a limitation in directly controlling the diameter and length to industrially applicable dimensions for practical use owing to their primary structure. Accordingly, the industrial application and use of CNTs are limited despite their excellent physical properties.
CNTs are generally produced by various techniques, such as arc discharge, laser ablation, and chemical vapor deposition. However, arc discharge and laser ablation are not appropriate for mass production of CNTs and require high arc production costs or expensive laser equipment. Chemical vapor deposition using a vapor dispersion catalyst has the problems of a very low synthesis rate and too small a size of final CNT particles. Chemical vapor deposition using a substrate-supported catalyst suffers from very low efficiency in the utilization of a reactor space, thus being inappropriate for mass production of CNTs. Thus, studies on catalysts and reaction conditions for chemical vapor deposition are currently underway to increase the yield of CNTs.
A need also exists for CNTs that have a small diameter and can be readily dispersed in and mixed with polymers during compounding with the polymers to manufacture composite materials with improved physical properties.

Catalyst for producing carbon nanotubes and carbon nanotubes produced using same