Systems and methods for allowing challenge messages to be sent directly to a recipient's inbox where normally the challenge message would be sent to a pending folder or deleted. Challenge messages sent between federated messaging services contain a federated token which can be identified, authenticated and validated to determine whether the challenge message should be sent to a recipient's inbox. The federated token can include an authentication portion and a validation portion. Authentication methods for the authentication portion can include, for example, checksums, salts, hashes and digital signatures. Once a federated token is authenticated by decrypting the authentication portion according to one or more of these authentication methods, the federated token is validated by determining the defined use-base and determining whether the receipt of the federated token satisfies the defined use.

1. The Field of the Invention
The present invention relates generally to systems and methods for delivering electronic messages. More particularly, embodiments of the invention relate to allowing challenge messages from federated messaging services to be delivered directly to a recipient's inbox if the challenge message is authenticated and validated.
2. Relevant Technology
Electronic messaging or e-mail has become, for many people, a primary means of communication. The ease by which a person is able to send and receive an electronic message makes this form of communication extremely attractive. Unfortunately, others utilize electronic messaging to send unsolicited bulk electronic messages, better known as "spam." Unsolicited electronic messages may include commercial advertisements, political messaging, as well as pornographic solicitations. Due to the influx of unsolicited electronic messages, people have become wary of giving out their electronic addresses for fear that their address will be sold to would-be solicitors. Further, those who receive spam are often not able to successfuilly request removal from mass e-mailing lists. Moreover, it is difficult to ascertain who has sent unsolicited electronic messages, since solicitors often use fabricated addresses or refrain from including one altogether.
Challenge and response mechanisms have been developed as a way to filter out unwanted electronic messages. When an electronic message is directed to a recipient, the message is delivered to the recipient only if the sender is identified as being authorized to send electronic messages to the recipient. Usually, the recipient has a list of approved senders, allowing the electronic message from the approved senders to be sent to the recipient's inbox without a challenge.
However, when the sender is unknown, a challenge message is sent to the sender to verify that the sender's address is valid and that the sender is a person as opposed to a machine before delivering the senders email to the recipient's inbox. The sender is confirmed by asking the sender to respond to the challenge message in a way that affirmatively verifies that the sender is a person as opposed to a machine. This challenge/response method is quite successful in eliminating unsolicited electronic messages that are sent by mass-mailers.
However, challenge/response systems are based on a set of rules that do not take into consideration certain scenarios in which a recipient would actually like to receive an incoming message. In these situations, the challenge/response system is overinclusive, meaning that the spam protection actually prevents wanted messages from being sent directly to the recipient. FIGS. 1A and lB illustrate two such scenarios.
In one example, shown in FIG. 1A, user A sends an original message from service A to user B associated with service B, the original messaging being addressed TO email@example.com and FROM firstname.lastname@example.com. Assuming this is the first time that user B has received an electronic message from user A, service B will generate a challenge message. The server generating the challenge message, in some cases, will place in the FROM field the identity of the server, resulting in a challenge message being addressed TO firstname.lastname@example.com and FROM email@example.com. Because service A will likely not recognize the address in the FROM field of the challenge message, service A will send the incoming challenge message to user A's pending folder and user A will not have the opportunity to reply.
Furthermore, if service A utilizes a challenge/response mechanism, service A will issue a second challenge in response to the incoming first challenge message containing the unknown address (i.e., email@example.com). The second challenge sent to service B may result in yet another challenge being sent to service A. Meanwhile, the original message from user A remains undelivered to user B at user B's server. Appreciably, a "challenge war" has been created in which multiple challenges are sent to both parties, and neither party is aware of the existence of an original message and/or challenge message.
In another example, shown in FIG. 1B, user A associated with messaging service A sends an original message to user B associated with messaging service B, the original messaging being addressed TO email@example.com and FROM firstname.lastname@example.com. Suppose user B's service B then forwards the message to user B's remote account user B1 associated with service C. With some forwarding mechanisms, the forwarding protocol creates an electronic message in which the FROM field uses the address of the original sender. Thus, a forwarded message may be addressed TO beta 1 firstname.lastname@example.com and FROM email@example.com. Assuming this is the first time service C has received a message from user A, service C send a challenge message to user A. Thus, a challenge message from service C will be addressed TO email@example.com from beta 1 firstname.lastname@example.com or postmastereserviceC.com. The challenge message will be sent to A's pending folder since the FROM address is unknown and the original message left undelivered to user B1.
Further, service A could send a subsequent challenge message to service C if it does not recognize the FROM address. However, because service C is unfamiliar with user A's address, the challenge message is sent to user B1's pending folder. Thus, both user A and user B1 will have challenge messages in their pending folders, but will not be aware of them or may become aware of them after the time for responding to the challenge message has expired. Furthermore, repeated attempts by user A to send messages to user B will continue to result in additional challenges by both services A and C, which creates a "challenge war" situation in which both parties are sending challenges and yet neither party is aware of the incoming challenges, while, in reality, it is likely that user A and user B1 would not consider messages from each other as spam.
Thus, conventional challenge and response filtering systems are overinclusive and present users from receiving desired challenge messages in situations where the user would actually like to receive the message. It would be advantageous to provide message filtering systems that are capable of delivering such electronic messages without issuing a challenge message or otherwise failing to deliver the messages.

Electronic message system with federation of trusted senders


A system and method are provided for performing the process known as "data mining" on a database of raw data records having common data elements, to obtain categorical cluster rules as to what elements of the data tend to occur in common in multiple records. Initial values are assigned to the elements. In an iterative process, the associated value for each given one of the elements is recalculated based on the values of other elements which occur in records together with the given element. Thus, the associated values will tend to grow for elements occurring together in multiple records. Those common occurrences of elements in multiple records represent categorical cluster rules the owner of the data is likely to want to know about. Thus, these rules may be identified based on the growth of the associated values for the records.

In recent years, the field of data mining, or extracting useful information from bodies of accumulated raw data, has provided a fertile new frontier for database and software technologies. While numerous types of data may make use of data mining technology, a few particularly illuminating examples have been those of (i) mining information, useful to retail merchants, from databases of customer sales transactions, and (ii) mining information from databases of commercial passenger airline travel. In the description that follows, these examples will be used illustratively.
Customer purchasing patterns over time can provide invaluable marketing information for a wide variety of applications. For example, retailers can create more effective store displays, and can more effectively control inventory, than otherwise would be possible, if they know that, given a consumer's purchase of a first set of items, the same consumer can be expected, with some degree of probability, to purchase a particular second set of items along with the first set. In other words, it would be helpful from a marketing standpoint to know association rules between itemsets (different products) in a transaction (a customer shopping transaction).
To illustrate, it would be helpful for a retailer of automotive parts and supplies to be aware of an association rule expressing the fact that 90% of the consumers who purchase automobile batteries and battery cables also purchase battery post brushes and battery post cleanser. (In the terminology of the data mining field, the latter are referred to as the "consequent.")
It will be appreciated that advertisers, too, can benefit from a thorough knowledge of such consumer purchasing tendencies. Still further, catalogue companies can conduct more effective mass mailings if they know the tendencies of consumers to purchase particular sets of items with other sets of items.
It is to be understood, however, that although this discussion focusses on the marketing applications of the present invention, database mining and, hence, the principles of the present invention, are useful in many other areas, e.g., business and science.
It happens that until recently, it was highly impracticable to build large, detailed databases that could chronicle thousands, and from a statistical view preferably millions, of consumer transactions. Deriving useful information from the databases (i.e., mining the databases), was even more impractical.
Consequently, marketing and advertising strategies have been based upon anecdotal evidence of purchasing patterns, if any at all, and thus have been susceptible to inefficiencies in consumer targeting that have been difficult, if not impossible, to overcome.
With the advent of modern technology, however, building large databases of consumer transactions has become possible. The ubiquitous bar-code reader can almost instantaneously read so-called basket data, i.e., when a particular item from a particular lot was purchased by a consumer, how many items the consumer purchased, and so on, for automatic electronic storage of the basket data.
Further, when the purchase is made with, for example, a credit card, the identity of the purchaser can be almost instantaneously known, recorded, and stored along with the basket data.
Still further, vastly improved data storage media have made it possible to electronically store vast amounts of such information for future use.
As alluded to above, however, building a transaction database is only part of the marketing challenge. Another important part is the mining of the database for useful information. Such database mining becomes increasingly problematic as the size of databases expands into the gigabyte, and indeed the terabyte, range.
Much work, in the data mining field, as gone to the task of finding patterns of measurable levels of consistency or predictability, in the accumulated data. For instance, where the data documents retail customer purchase transactions, purchasing tendencies, and, hence, particular regimes of data mining, can be classified many ways.
One type of purchasing tendency has been called an "association rule."
In a conventional data mining system, working on a database of supermarket customer purchase records, there might be an association rule that, to a given percent certainty, a customer buying a first product (say, Brie cheese) will also buy a second product (say, Chardonnay wine). It thus may generally be stated that a conventional association rule states a condition precedent (purchase of the first product) and a condition subsequent or "consequent" (purchase of the second product), and declares that, with, say 80% certainty, if the condition precedent is satisfied, the consequent will be satisfied, also.
Methods for mining transaction databases to discover association rules have been disclosed in Agrawal et al., "Mining Association Rules Between Sets of Items in Large Databases", Proc. of the ACM SigMod Conf. on Management of Data, May 1993, pp. 207-216, and in Houtsma et al., "Set-Oriented Mining of Association Rules", IBM Research Report RJ 9567, October, 1993.
Early data mining approaches have had various drawbacks, which presented challenged for data mining pioneers to overcome. One such drawback was the requirement of excessive memory and of multiple data sorts and/or passes attributable to generating candidate itemsets of interest on-the-fly, that is during a pass over the data, which resulted in unduly prolonged processing time. Further, prior methods had not specifically addressed database structure or buffer management problems. Moreover, prior methods were incapable of discovering association rules having more than a single item in the consequent (the right-hand side of a rule), and accordingly were limited in their ability to discover useful association rules.
These and other data mining objectives have been addressed in Agrawal et al., U.S. Pat. No. 5,615,341, "System and Method for Mining Generalized Association Rules in Databases," and in co-pending, co-assigned U.S. patent applications Ser. No. 08/415,006, filed Mar. 31, 1995 now U.S. Pat. No. 5,796,209, Ser. No. 08/500,717, filed Jul. 11, 1995, Ser. No. 08/577,945 now U.S. Pat. No. 5,724,573, filed Dec. 22, 1995, and Ser. No. 08/735,911, filed Oct. 25, 1996 based on a foreign priority date of Oct. 26, 1995 now U.S. Pat. No. 5,812,997.
However, association rules have been limited in scope, in the sense that the conditions precedent and subsequent fall within the same column or field of the database. In the above example, for instance, cheese and wine both fall within the category of supermarket items purchased.
The field remains ripe for new, creative approaches to data mining, to further assist data system users to extract useful information from their accumulated data.

System and method for data mining from relational data by sieving through iterated relational reinforcement

International Business Machines Corporation


A method and state stabilizer for enhancing computing functionality by using fast excitations are described. The state stabilizer includes a voltage source for producing fast excitations having an associated excitation amplitude. An electronic device having an associated negative differential resistance region is also included. The excitation amplitude is greater than a width of the negative differential resistance region.

FIG. 1A is a circuit diagram for a conventional circuit 100 with a DC power source 110, inductor 120, capacitor 130, and resonant tunneling diode (RTD) 140. The presence of the RTD 140 creates instability in the circuit 100 that is more clearly seen in FIG. 1B. This figure is a graph of the current voltage relationship, which is commonly referred to as an I-V curve, for the RTD 140. For a first region labeled 142, the current increases up to a peak current Ip that has an associated peak voltage Vp. In contrast, the current within a region labeled 144 decreases with increasing voltage to a valley current Iv that has an associated valley voltage Vv. Finally, the current increases again with increasing voltage in a region labeled 146 beyond the valley current Iv. Because resistance is the ratio of voltage to current, analyzing the I-V curve in FIG. 1B indicates how the resistance in the circuit 100 varies.
The behavior of the circuit 100 in the 144 region is caused primarily by the RTD 140 and the quantum mechanical phenomenon called tunneling. In essence, tunneling is the quantum mechanical process by which a particle can penetrate a classically forbidden region of space (for example, passing from two separate points A and B without passing through intermediate points). The phenomenon is so named because the particle, in traveling from A to B, creates a sort of "tunnel" for itself, bypassing the usual route. As indicated in FIG. 1B, tunneling occurs during the region labeled 144, which consequently results in the current decreasing with increasing voltage. This region is generally referred to as the region of negative differential resistance (NDR). One skilled in the art can appreciate that the NDR depicted in region 144 means that
            ⅆ      V              ⅆ      I        <  0because the first derivative represents the slope of the line. Therefore,
      ⅆ    V        ⅆ    I  is the differential resistance.
The NDR region for RTDs can be both an advantage and a disadvantage in modern computing applications. When the RTD is used in amplifier devices, the NDR region can be quite helpful. In contrast, the NDR's existence creates a host of problems when used in logic devices, such as AND gates, OR gates, and NOR gates. One of the primary characteristics of these gates is that they produce a consistent output for a given input. In other words, logic devices must be stable. Because the NDR is by its nature unstable, using an RTD in a logic device is considerably limiting.
In other words, RTDs can only be used in logic devices within its stable regions (i.e., region 142 and region 146). This is more clearly seen with reference to FIG. 1C and FIG. 1D. In FIG. 1C, the circuit 145 includes two RTDs 140 and a DC source 110. FIG. 1D illustrates the corresponding I-V curves for this circuit. In essence, the circuit 145 creates two stable states 150, 152 and an unstable state 160. Hence, the RTDs 140 can be used in the regions that include the stable states 150, 152 but cannot be used in the NDR region that includes the unstable state 160. This inherent characteristic of the RTD considerably limits its use. Thus, there remains an unmet need among conventional devices.
While the invention is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and subsequently are described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed. In contrast, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

Method and apparatus for stability control using fast excitation in circuits having elements with negative differential resistance

The Regents of the University of California


The process for serially transmitting information entities over a serial bus between subscribers (ECU1 to ECU4) at a common transmission rate for all subscribers, includes providing the information entities with a start bit (Sta) at a beginning of transmission of each of the information entities; waiting to transmit the information entities on the bus from each subscriber until after a bus monitoring time period (T.sub.U) assigned to each subscriber has elapsed; setting a flag after a subscriber receives one of the information entities; monitoring a logic state of the serial bus during a bus monitoring time period (T.sub.U) at a monitoring rate sufficiently high so that receipt of each information entity is detected during reception of a start bit (Sta); each subscriber determining the state of the flag after expiration of the bus monitoring period (T.sub.U); and only then transmitting the information entities from the subscriber if the subscriber does not detect that the flag is set during the bus monitoring time period (T.sub.U).

The invention is directed to a process for information transmission and, more particularly, to a process for transmitting information entities serially between subscribers connected by a serial bus.
Increasingly, data processing technique makes use of networks of computers or the like. Different bus systems are known for these network functions. The information stream between a number of electronic components (for example, between control devices) also continues to increase in automobile technology. For example, the so-called CAN system (CAN=Controller Area Network) (cf. DE-OS 35 06 118) or ABUS system (ABUS=Automobile Bit-Serial Universal Interface) are presently used in motor vehicles for linking individual components. The objective of every communications system is to link individual components (subscribers) via bus lines so that they can communicate with one another via a central system or e.g. via an externally connected tester. In this respect there is a special case of communications relating to diagnostics. In this case an external testing device addresses one or more control devices for interrogating corresponding states. Due to competing subscribers, the problem of so-called bus arbitration occurs regardless of the type of bus system. Thus, it must be ensured that no more than one subscriber occupies the bus at one time, since this would lead to inaccurate information and/or loss of information. Like the Carrier Sense Multiple Access with Collision Detection (CSMA/CD) which is used to manage an ETHERNET bus, the aforementioned systems (CAN, ABUS) also work on the principle of priority ranking and checking of the transmitted information. In the case of CSMA/CD mentioned above, the information is lost in the event of collision and must be retransmitted. In CAN and ABUS, the message with higher priority is transmitted and the message with lower priority must be retransmitted. The known processes require independent hardware for bus connection and management.

Process for information transmission in a bus system having several participants


A method of preparing a catalyst comprising contacting a support with a trivalent titanium compound and a chromium-containing compound. A catalyst composition comprising a support, chromium, and titanium, wherein the titanium is derived from TiCl3, Ti2(SO4)3, Ti(OAc)3, Ti(+3) oxylate, Ti(NO3)3, Ti(+3) lactate or combinations thereof.

Olefin polymerization catalysts are known in the art, however methods of producing these catalysts may suffer from a variety of drawbacks. Enhancements in preparation methods for olefin polymerization catalysts can reduce the costs associated with catalyst production and improve process economics. Thus, there is an ongoing need to develop new methods of preparing olefin polymerization catalysts.

Methods of preparing a polymerization catalyst


This invention relates to a focal position detection apparatus for detecting a positional shift between the imaging position of an object image formed by a predetermined objective optical system and the detection surface of the object image. This apparatus includes a beam splitter for extracting part of a light beam from the objective optical system, splitting the light beam into at least three light beams, and guiding the split light beams to the light-receiving surface of a photo-sensing device arranged at a predetermined position. This beam splitter guides at least the three split light beams to a standard optical path and a pair of reference optical path and forms a standard image at a predetermined position in the standard optical path and a pair of reference images at predetermined positions in the pair of optical paths, respectively. The imaging positions of the pair of reference images are shifted from each other in opposite direction with respect to the imaging surface on which the standard image is formed. The apparatus detects a positional shift by using the optically symmetry of at least one pair of reference images in a focusing state with respect to the standard image.

1. Field of the Invention
The present invention relates to a focal position detection apparatus applicable to the auto-focusing mechanism of an optical equipment such as a microscope, a still camera, a video camera, or the like.
2. Related Background Art
In an optical equipment such as a microscope, a still camera, or a video camera, an object image is formed on a predetermined detection surface through an objective optical system, and the formed image is picked up using an image pickup element such as a CCD, a film, or the like. Such optical equipment has an auto-focusing mechanism to photograph a sharp object image. An important portion of the auto-focusing mechanism is a focal position detection apparatus for detecting a positional shift between the imaging plane (focal position) of the objective optical system and the image pickup surface (image detection surface) of the image pickup device.

Focal position detection apparatus having a light reflecting member with plural reflecting films


The present invention is directed to a flexible controlled release film for delivering a medicinal or cosmetic agent, e.g., through the skin of a subject, which delivery system comprises (a) a microembossed flexible film including microcells; (b) a liquid composition filled in the microcells wherein said liquid composition comprises the medicinal or cosmetic agent; and (c) a flexible sealing layer to enclose the liquid composition within the microcells.

Various structures with peripheral plates or walls containing a liquid component were previously known. For example, a liquid component may be filled between two parallel or near-parallel surfaces and, in such a case, the liquid component is present in a continuous form. The two plates may be edge sealed first with fill holes for subsequent filling of the liquid component. Alternatively, the liquid component may be dropped on one of the two plates (before or after application of the edge sealing adhesive), followed by placing a second plate on top of the first plate to contain the liquid component between the two plates. In some cases, spacers may be present in the continuous liquid phase to control the distance between the two plates. However, such a continuous liquid phase structure suffers certain disadvantages. For example, it lacks structure integrity and depth control, especially when the plates are flexible substrates. In addition, this type of structure is not format flexible for production and, if hard surface plates are involved, batch manufacturing is required which results in low production efficiency.
It is also possible to divide a liquid component into small compartments, for example, by microencapsulation. Individual droplets are wrapped by a wall material to form discreet compartments and such compartments are arranged between two parallel or near-parallel surfaces. There are numerous examples of microencapsulation of a liquid component for different types of applications. In the display field, for example, there are encapsulated electrophoretic displays and encapsulated cholesterolic liquid crystal displays. In the pharmaceutical field, drugs may be encapsulated for controlled release. In the imaging field, dye and UV curable monomers may be encapsulated for light/pressure induced imaging development. In this approach, the performance of an encapsulated product or device often depends on the size distribution of the microcapsules. It could be challenging to control the size of the microcapsules to be within a desired range. In addition, the capsule wall usually does not provide good mechanical support for structural integrity, especially with flexible substrates. Material selection is another issue with the microencapsulation technique. In many cases, extra chemical(s) are necessary to stabilize the dispersed phase; the extra chemical(s), however, could be detrimental to the final product.
U.S. Pat. No. 6,930,818 and related patents and patent applications describe a microcup structure for monochrome or multi-color electrophoretic displays. An electrophoretic display device is formed when the microcups are filled with an electrophoretic fluid comprising charged pigment particles dispersed in a dielectric solvent or solvent mixture. U.S. Pat. No. 6,795,138 and related patents and patent applications disclose a liquid crystal display, also utilizing the microcup structure. The liquid crystal composition filled in the microcups may further comprise one or more guest dye(s), in particular, dichroic dye(s). US Patent Application Publication No. 2005-0012881A describes a display device which can display a 3-dimensional image and such a display device is formed when the microcups are filled with an optically active electrophoretic dispersion. US Patent Application Publication No. 2006-0139724 discloses an electrodeposition or electrochromic display device which is formed when the microcups are filled with an electrolyte fluid or an electrochromic fluid. The contents of all of the patents and patent applications referred to above are incorporated herein by reference in their entirety.


A dense, self-reinforced silicon nitride ceramic body and a method of making such body. The body has a composition that includes: (a) silicon nitride; (b) a glassy grain boundary phase containing oxygen, nitrogen, magnesium, yttrium, silicon, zirconium, and at least one of titanium and aluminum; and (c) a second crystalline phase containing zirconium oxide; and (d) crystalline phases of metal zirconium silicide and/or metal zirconium silicon nitride. The ceramic exhibits high fracture toughness and high fracture strength and has a density at least 98 percent of theoretical.

This invention pertains to a sintered self-reinforced silicon nitride ceramic body and to compositions used in preparing the same.
Silicon nitride ceramics are recognized for their excellent mechanical and physical properties, including good wear resistance, low coefficient of thermal expansion, good thermal shock resistance, high creep resistance, and high electrical resistivity. In addition, silicon nitride ceramics resist chemical attack, particularly oxidation. Because of these attributes, silicon nitride is useful in a variety of wear and high temperature applications, such as cutting tools and parts in pumps and engines.
Typically, densification of silicon nitride requires the presence of densification aids, such as oxides of magnesium, yttrium, aluminum, cerium, silicon, and zirconium. A powder mixture comprising silicon nitride and one or more of such densification aids is usually prepared and heated under conditions described hereinafter. The densification aids form a liquid phase into which .alpha.-silicon nitride dissolves and from which it precipitates as .beta.-silicon nitride.
The final density of a ceramic body depends largely on the density of the body before heat is applied. This is often referred to as "green density," and the body is referred to as "greenware." The most common method of forming greenware is dry pressing. However, a problem with dry pressing is that it does not favor forming large and complex shaped bodies. In addition, forming greenware by dry pressing typically results in low density parts with non-uniform distributions of porosity. The non-uniformity generally relates to a higher density at the edge of a ceramic part than in the center. Further, binders, used to process the bodies into their near net shapes, usually have to be removed. De-bindering is a long and difficult process that often leads to development of internal cracks within the body.
An alternative method of forming ceramic greenware is by colloidal processing, such as slip-casting. An advantage of colloidal processing is that large, complex shaped, high density greenware can be produced without the use of binders. A second advantage is that aqueous carrier media may be used, eliminating the need for more expensive or potentially environmentally hazardous processing conditions. Notwithstanding these advantages, colloidal processing has one major disadvantage in that as the number of components in a formulation increases, it becomes more difficult to find common colloidal processing conditions. This is because every component has different surface characteristics, and these characteristics determine the conditions in which colloidal processing will work. Thus, for many multi-component ceramic compositions, it is difficult to form ceramic greenware by colloidal processing.
Typically, in order to obtain substantially full densification of the aforementioned powder mixture or greenware, one of four general methods is used: hot pressing (HP), hot isostatic pressing (HIP), pressure-less sintering, or low pressure gas sintering. Densification of silicon nitride alone normally does not go to completion in the absence of high pressure. For example, the density of the silicon nitride ceramic body might only reach 80 or 90 percent of its theoretical value. Whereas a density of at least 98 percent is required to achieve a ceramic having excellent mechanical and physical properties, such as high fracture strength and high fracture toughness. Further, at high temperatures and low pressures, silicon nitride decomposes into elemental silicon and nitrogen. Thus, the commercial need for fully densified silicon nitride ceramics, having excellent fracture strength and fracture toughness, is currently met predominantly by using HP or HIP to densify combinations of silicon nitride and densification aids.
Disadvantageously, however, the HP and HIP methods require complicated high pressure equipment and typically yield only a ceramic having a simple shape. In order to obtain a more complicated net shape, the densified HP or HIP ceramic typically must be subjected to post-densification procedures such as diamond grinding. Although more complicated shapes may be obtained by pressureless or low pressure gas sintering, these methods typically present difficulties in obtaining ceramic bodies of substantially full density having high fracture strength and toughness.

Sintered self-reinforced silicon nitride


This invention is concerned with actively shielded magnetic resonance (MR) devices and more particularly with an improved system which includes only a single former. All the coils of the system those with backward current and those with forward current, can all be wound in a single process on a single former machined during a single installation.

MRI magnets, used for diagnostic imaging, usually use superconducting coils to generate the high intensity static magnetic field needed in such systems and some type of a shield to prevent stray field from contaminating spaces where general public has access.
There are two basic methods for shielding the MRI magnet: ferromagnetic shielding and active shielding. The first method involves placing iron around the MRI magnet in form of a return Yoke.
The second method involves using active shielding magnets. The methods for active shielding magnets use counter-running coils with currents in opposite directions and iron in various combinations.
In active shielding for MRI systems two sets of coils are used: a first set of coils, responsible for the main homogenous magnetic field, and a second coil system, which is used to provide the active shielding. Usually the coils are made of superconductive material.
When constructing an active shield magnet prior art has required that the outer and inner magnets are wound on separate formers and the formers themselves are later assembled together. This was because coils overlapped along the Z axis.
In order to assemble the shielding coils, which may be subject to significantly large forces, it is necessary to have massive components to accommodate the fixings. It is an unfortunate consequence of this technique that the accumulation of the smallest tolerances and relative movements of parts of the assembly under load leads to important degradation of homogeneity.
Technically each set of coils was fitted in slots on its own special coil support which is called a former, i.e. the first set of coils 22 responsible for the main homogenous magnetic field is fitted on a first former 23, and the second set of coils 21 responsible for the active shielding is fitted on a second former 24 (FIG. 1). This structure which uses at least two separate formers for an MRI system was disclosed in prior art see for example U.S. Pat. Nos.: 5,329,266, 5,210,512, 5,296,810, 4,890,082, 5,045,826. In particular, Elscint's U.S. Pat. No. 5,012,217 on an integrated active shielded magnet is further improved by this disclosure.
Active shield magnets for use in MRI can be constructed in two principal ways. Either the wire is wound directly onto a former or the wire is wound into a mould and impregnated with resin. The second method produces separate free-standing coils which can be assembled onto a former or formers at a later time. Both methods have been used to construct working magnets.
Winding the wire directly onto a former is today the preferred method by the MRI manufacturer. When winding the wire directly onto the former the process time is shortened, thus saving valuable time. Furthermore the direct winding is more accurate in placing the coils exactly at the right position on the former compared with the moulding-assembly route.
Active shield systems with more than one former, as disclosed in prior art, have many disadvantages. For example it is difficult to assemble the two formers, thus the accuracy of the system is decreased. Another disadvantage of such a system is its size which is usually large. Yet another disadvantage of the two-former system is the fact that its coils can not be wound on the former itself in a single process. This means that the winding process becomes more expensive,, slower, and less accurate!.
One solution offered by prior art to try and solve the difficulty in assembling the two formers was using some type of a single former. For example see U.S. Pat. No. 5,136,273. In this cited art a single former is used and the shielding coils are placed at the ends of the former at a larger radius than the inner main coils. Such a solution as described in the above cited art solves the assembly problem but does not enable winding the coils in a single process nor does it give the most compact solution for a given homogeneity.
Because the coils cannot all be wound directly onto the single former, the possibility of achieving improved accuracy is lost.
Thus, a compact MRI magnet with a single former which allows a single winding process is most desired. Such a system offers great advantages in the construction of the magnet by making the coil winding process faster, cheaper, and easier to control.
It is the intention of the present invention to introduce an improved active shielding MRI system which is more compact, and uses a single former which can be wound in a single process.


A tissue sheet is made using a modified wet pressing machine in a modified wet pressing process employing an integrally sealed air press. After initial formation and conventional vacuum dewatering, the wet web is conformed to the surface contour of a relatively coarse fabric to give the web a textured surface. By creating a pressure differential across the web of at least 30 inches of mercury and an air stream through the web of at least 500 SCFM/in2, the air press noncompressively dewaters the wet web to a consistency of about 30 to about 40 percent prior to a heated drying cylinder. The web is dried to substantially preserve its three-dimensional, throughdried-like texture. The process provides a web having an exceptionally high degree of bulk and absorbency not expected in wet-pressed products.

The present invention relates generally to methods for making paper products. More particularly, the invention concerns methods for making cellulosic webs having high bulk and absorbency on a modified conventional wet-pressed machine.
There are generally two different methods for making the base sheets for paper products such as paper towels, napkins, tissue, wipes and the like. These methods are commonly referred to as wet-pressing and throughdrying. While the two methods may be the same at the front end and back end of the process, they differ significantly in the manner in which water is removed from the wet web after its initial formation.
More specifically, in the wet-pressing method, the newly-formed wet web is typically transferred onto a papermaking felt and thereafter pressed against the surface of a steam-heated Yankee dryer while it is still supported by the felt. As the web is transferred to the surface of the Yankee dryer, water is expressed from the web and is absorbed by the felt. The dewatered web, typically having a consistency of about 40 percent, is then dried while on the hot surface of the Yankee dryer. The web is then creped to soften it and provide stretch to the resulting tissue sheet. A disadvantage of wet pressing is that the pressing step densifies the web, thereby decreasing the bulk and absorbency of the tissue sheet. The subsequent creping step only partially restores these desirable sheet properties.
In the throughdrying method, the newly-formed web is first dewatered using vacuum and then transferred to a relatively porous fabric and non-compressively dried by passing hot air through the web. The resulting web can then be transferred to a Yankee dryer for creping. Because the web is substantially dry when transferred to the Yankee dryer, the density of the web is not significantly increased by the transfer. Also, the density of a throughdried sheet is relatively low by nature because the web is dried while supported on the throughdrying fabric. The disadvantages of the throughdrying method are the relatively high operational energy costs and the capital costs associated with the throughdryers.
Because the vast majority of existing tissue machines utilize the older wet-pressing method, it is of particular importance that manufacturers find ways to modify existing wet-pressed machines to produce the consumer-preferred low-density products without expensive modifications to the existing machines. Of course, it is possible to re-build wet-pressed machines to throughdried configurations, but this is usually prohibitively expensive. Many complicated and expensive changes are necessary to accommodate the throughdryers and associated equipment. In addition, the length of a through-air dried tissue machine is greater, requiring a building addition or modification. In some locations, building modifications are not practical or possible, or prohibitively expensive because of the interference with other existing equipment or limited area available on the site. Accordingly, there has been great interest in finding ways to modify existing wet-pressed machines without significantly altering the machine design.
In some instances, it is more convenient and cost effective to modify the press section of a wet-pressed tissue machine than the wet end, particularly if the wet end and headbox are in good condition. In addition, older wet-pressed machines may have existing equipment associated with the bottom felt run that can be readily adapted for other uses, making the modification simpler and even more cost effective. This invention discloses simplified methods of modifying a wet-pressed machine to make an improved consumer-preferred low-density product.
One simple approach to modifying a wet-pressed machine to produce softer, bulkier tissue is described in U.S. Pat. No. 5,230,776 issued Jul. 27, 1993 to Andersson et al. The patent discloses replacing the felt with a perforated belt of wire type and sandwiching the web between the forming wire and this perforated belt up to the press roll. The patent also appears to disclose additional dewatering means, such as a steam blowing tube, a blowing nozzle, and/or a separate press felt, that may be placed within the range of the sandwich structure in order to further increase the dry solids content before the Yankee dryer. These extra drying devices are said to permit the machine to run at speeds at least substantially equivalent to the speed of throughdrying machines.
It is important to reduce the moisture content of the web coming onto the Yankee dryer, to maintain machine speed and to prevent blistering or lack of adhesion of the web. Referring to U.S. Pat. No. 5,230,776, the use of a separate press felt, however, tends to densify the web in the same manner as a conventional wet-pressed machine. The densification resulting from a separate press felt would thus negatively impacting the bulk and absorbency of the web.
Further, jets of air for dewatering the web are not per se effective in terms of water removal or energy efficiency. Blowing air on the sheet for drying is well known in the art and used in the hoods of Yankee dryers for convective drying. In a Yankee dryer hood, however, the vast majority of the air from the jets does not penetrate the web. Thus, if not heated to high temperatures, most of the air would be wasted and not effectively used to remove water. In Yankee dryer hoods, the air is heated to as high as 900 degrees Fahrenheit and high residence times are allowed in order to effectuate drying.
Thus, what is lacking and needed in the art is a practical method for making tissue sheets having high bulk and absorbency comparable to throughdried sheets on a modified, conventional wet-pressed machine.
It has now been discovered that a wet-pressed tissue can be made having bulk and absorbency properties equivalent to those of comparable throughdried products, while maintaining reasonable machine productivity. More particularly, wet-pressed cellulosic webs can be made by vacuum dewatering a wet web up to approximately 30 percent consistency, then using an integrally sealed air press to noncompressively dewater the sheet to 30 to 40 percent consistency. The wet web is desirably then transferred to a xe2x80x9cmoldingxe2x80x9d fabric substituted for the conventional wet-pressing felt in order to impart more contour or three-dimensionality to the wet web. The wet web is preferably thereafter pressed against the Yankee dryer while supported by the molding fabric and dried. The resulting product has exceptional wet bulk and absorbency exceeding that of conventional wet-pressed towels and tissue and equal to that of presently available throughdried products.
As used herein, xe2x80x9cnoncompressive dewateringxe2x80x9d and xe2x80x9cnoncompressive dryingxe2x80x9d refer to dewatering or drying methods, respectively, for removing water from cellulosic webs that do not involve compressive nips or other steps causing significant densification or compression of a portion of the web during the drying or dewatering process.
The wet web is wet-molded in the process to improve the three-dimensionality and absorbent properties of the web. As used herein, xe2x80x9cwet-moldedxe2x80x9d tissue sheets are those which are conformed to the surface contour of a molding fabric while at a consistency of about 30 to about 40 percent and then dried by thermal conductive drying means, such as a heated drying cylinder, as opposed to other drying means such as a throughdryer, before optional additional drying means.
The xe2x80x9cmolding fabricsxe2x80x9d suitable for purposes of this invention include, without limitation, those papermaking fabrics which exhibit significant open area or three-dimensional surface contour sufficient to impart greater z-directional deflection of the web. Such fabrics include single-layer, multi-layer, or composite permeable structures. Preferred fabrics have at least some of the following characteristics: (1) On the side of the molding fabric that is in contact with the wet web (the top side), the number of machine direction (MD) strands per inch (mesh) is from 10 to 200 (3.94 to 78.74 per centimeter) and the number of cross-machine direction (CD) strands per inch (count) is also from 10 to 200 (3.94 to 78.74 per centimeter). The strand diameter is typically smaller than 0.050 inch (1.27 mm); (2) On the top side, the distance between the highest point of the MD knuckle and the highest point of the CD knuckle is from about 0.001 to about 0.02 or 0.03 inch (0.025 mm to about 0.508 mm or 0.762 mm). In between these two levels, there can be knuckles formed either by MD or CD strands that give the topography a 3-dimensional hill/valley appearance which is imparted to the sheet during the wet molding step; (3) On the top side, the length of the MD knuckles is equal to or longer than the length of the CD knuckles; (4) If the fabric is made in a multi-layer construction, it is preferred that the bottom layer is of a finer mesh than the top layer so as to control the depth of web penetration and to maximize fiber retention; and, (5) The fabric may be made to show certain geometric patterns that are pleasing to the eye, which typically repeat between every 2 to 50 warp yarns.
Hence, in one aspect, the invention resides in a method for making a cellulosic web, comprising: (a) depositing an aqueous suspension of papermaking fibers onto an endless first fabric to form a wet web; b) dewatering the wet web to a consistency of about 10 percent to about 30 percent; c) transferring the wet web to an endless second fabric; d) sandwiching the wet web between the second fabric and a support fabric and dewatering the wet web to a consistency of greater than 30 percent using a noncompressive dewatering device that is adapted to cause a pressurized fluid at about 5 pounds per square inch gauge or greater to flow substantially through the web due to an integral seal formed with the wet web; (e) pressing the dewatered wet web against the surface of a heated drying cylinder to at least partially dry the wet web; and, (f) drying the dewatered wet web to a final dryness.
In another aspect, the invention resides in a method for making a cellulosic web, comprising: (a) depositing an aqueous suspension of papermaking fibers onto an endless first fabric to form a wet web wherein the wet web; (b) transferring the wet web to an endless second fabric; (c) sandwiching the wet web between the second fabric and a support fabric and dewatering the wet web to a consistency of up to about 30 percent; (d) supplementally dewatering the wet web to a consistency of about 30 to about 40 percent using an air press that is adapted to cause a pressurized fluid at about 5 pounds per square inch gauge or greater to flow substantially through the web due to an integral seal formed between an air plenum and a collection device; (e) configuring the second fabric to provide an unsupported sheet wrap angle of the dewatered wet web about a pressure roll of less than 90 degrees; (f pressing the dewatered wet web against the surface of a heated drying cylinder to at least partially dry the dewatered wet web; and, (g) drying the dewatered wet web to a final dryness.
In another aspect, the invention resides in a method for making a cellulosic web, comprising: (a) depositing an aqueous suspension of papermaking fibers onto an endless first fabric to form a wet web; (b) dewatering the wet web to a consistency of up to about 10 percent; (c) transferring the wet web to an endless second fabric; (d) sandwiching the wet web between the second fabric and a support fabric; e) passing the wet web sandwiched between the second fabric and the support fabric between an air plenum and a collection device with the second fabric disposed between the wet web and the collection device, the air plenum and collection device being operatively associated and adapted to create a pressure differential across the wet web of about 30 inches of mercury or greater and a stream of pressurized fluid through the wet web of about 10 standard cubic feet per minute per square inch or greater; f) dewatering the wet web using the stream of pressurized fluid to a consistency of about 30 percent to about 40 percent; g) pressing the dewatered wet web against the surface of a heated drying cylinder with the second fabric; and, (h) drying the dewatered wet web to a final dryness.
In another aspect, the invention resides in a method of modifying a conventional wet press machine having at least one felt and compressive dewatering devices, comprising: (a) replacing at least one felt with at least one fabric; and, (b) replacing compressive dewatering devices with non-thermal, noncompressive dewatering devices. Wet press processing and equipment are discussed in U.S. Pat. No. 4,139,410 issued to Tapio et al. on Feb. 13, 1979 and incorporated herein by reference.
In another aspect, the invention resides in a method for making a cellulosic web, comprising the steps of: (a) depositing an aqueous suspension of papermaking fibers onto an endless first fabric to form a wet web; (b) dewatering the wet web to a consistency to about 10 to about 30 percent; (c) transferring the wet web to an endless second fabric; (d) sandwiching the wet web between the second fabric and a support fabric and dewatering the wet web to a consistency of greater than about 30 percent using a non-compressive dewatering device that is adapted to cause a pressurized fluid at about 5 pounds per square inch gauge or greater to flow substantially through the wet web due to an integral seal formed with the wet web; (e) transferring the wet web back to the second fabric; (f) pressing the dewatered wet web against the surface of a heated drying cylinder to at least partially dry the wet web; and, (g) drying the wet web to a final dryness.
In another aspect, the invention resides in a method for making a cellulosic web, comprising the steps of: (a) depositing an aqueous suspension of papermaking fibers onto an endless first fabric to form a wet web; (b) transferring the wet web to an endless second fabric; (c) sandwiching the wet web between the second fabric and a support fabric and dewatering the wet web to a consistency to about 30 percent; (d) further dewatering the wet web to a consistency of greater than about 30 percent to about 40 percent using an air press that is adapted to cause a pressurized fluid at about 5 pounds per square inch gauge or greater to flow substantially through the wet web due to an integral seal formed between an air plenum and a collection device; (e) transferring the wet web back to the second fabric such that the sheet wrap of the wet web on the pressure roll is less than 90xc2x0; (f) pressing the dewatered wet web against the surface of a heated drying cylinder to at least partially dry the wet web; and, (g) drying the wet web to a final dryness.
In yet another aspect, the invention resides in a method for making a cellulosic web, comprising the steps of: (a) depositing an aqueous suspension of papermaking fibers onto an endless first fabric to form a wet web; (b) dewatering the wet web to a consistency of about 10 percent to about 30 percent; (c) transferring the wet web to another fabric; (d) sandwiching the wet web between the second fabric and a support fabric, one of which utilizes the space and components formerly used in the bottom felt run of a tow press wet press machine; (e) dewatering the wet web to a consistency of greater than about 30 percent to about 40 percent using an air press that is adapted to cause a pressurized fluid at about 5 pounds per square inch gauge or greater to flow substantially through the web due to an integral seal formed between an air plenum and a collection device; (f) transferring the wet web back to the second fabric; (g) pressing the dewatered and wet web against the surface of a heated drying cylinder to at least partially dry the web; (h) drying the web to a final dryness.
In another aspect, the invention resides in a method for making a cellulosic web, comprising the steps of: (a) depositing an aqueous suspension of papermaking fibers onto an endless first fabric to form a wet web to make a wet web; (b) transferring the wet web to an endless second fabric; (c) sandwiching the wet web between the second fabric and a support fabric and dewatering the wet web to a consistency of about 10 percent to about 30 percent; (d) further dewatering the wet web to a consistency of greater than about 30 percent to about 40 percent using an air press that is adapted to cause a pressurized fluid at about 5 pounds per square inch gauge or greater to flow substantially through the web due to an integral seal formed between an air plenum and a collection device; (e) transferring the wet web back to the second fabric to give the web a bulk of about 8 cubic centimeter per gram or greater; (f) pressing the dewatered web against the surface of a heated drying cylinder with a fabric to preserve the bulk of about 8 cubic centimeter per gram or greater; and, (g) drying the web to a final dryness.
In yet another aspect, the invention resides in a method for making a cellulosic web, comprising the steps of: (a) depositing an aqueous suspension of papermaking fibers onto an endless first fabric to form a wet web; (b) transferring the wet web to an endless second fabric; (c) sandwiching the web between the second fabric and a support fabric; (d) passing the second and support fabrics with the wet web sandwiched therewithin between an air plenum and a collection device with the second fabric disposed between the wet web and the collection device; the air plenum and the collection device being operatively associated and adapted to create a pressure differential across the wet web of about 30 inches of mercury or greater and a stream of pressurized fluid through the wet web of about 10 standard cubic feet per minute per square inch or greater; (e) dewatering the wet web using the stream of pressurized fluid to a consistency of about 30 percent or greater; (e) pressing the wet web against the surface of a heated drying cylinder with the second fabric; and, (f) drying the web to a final dryness.
The term xe2x80x9cfirst fabricxe2x80x9d is used herein to refer to any fabric used in tissue making as described herein or known in the art, including, but not limited to, forming, molding, and other support fabrics used in making tissue. However, the first fabric is preferably a forming fabric. The term xe2x80x9csecond fabricxe2x80x9d is used herein to refer to any fabric used in tissue making as described herein or known in the art, including, but not limited to, forming, molding, and other support fabrics used in making tissue. However, the second fabric is preferably a molding fabric as described herein. Where the second fabric is a molding fabric, the resulting web is a molded web. The term xe2x80x9csupport fabricxe2x80x9d is used herein to refer to any fabric used in tissue making as described herein or known in the art, including, but not limited to, forming, molding, or any other fabric used in making tissue.
The terms xe2x80x9cintegral sealxe2x80x9d and xe2x80x9cintegrally sealedxe2x80x9d are used herein to refer to: the relationship between the air plenum and the wet web where the air plenum is operatively associated and in indirect contact with the web such that about 85 percent or greater of the air fed to the air plenum flows through the web when the air plenum is operated at a pressure differential across the web of about 30 inches of mercury or greater; and the relationship between the air plenum and the collection device where the air plenum is operatively associated and in indirect contact with the web and the collection device such that about 85 percent or greater of the air fed to the air plenum flows through the web into the collection device when the air plenum and collection device are operated at a pressure differential across the web of about 30 inches of mercury or greater.
The air press is able to dewater the wet web to very high consistencies due in large part to the high pressure differential established across the web and the resulting air flow through the web. In particular embodiments, for example, the air press can increase the consistency of the wet web by about 3 percent or greater, particularly about 5 percent or greater, such as from about 5 to about 20 percent, more particularly about 7 percent or greater, and more particularly still about 7 percent or greater, such as from about 7 to 20 percent. Thus, the consistency of the wet web upon exiting the air press may be about 25 percent or greater, about 26 percent or greater, about 27 percent or greater, about 28 percent or greater, about 29 percent or greater, and is desirably about 30 percent or greater, particularly about 31 percent or greater, more particularly about 32 percent or greater, such as from about 32 to about 42 percent, more particularly about 33 percent or greater, even more particularly about 34 percent or greater, such as from about 34 to about 42 percent, and still more particularly about 35 percent or greater.
By adding the integrally sealed air press dewatering step to the process, considerable improvements over the previously described existing processes can be achieved. First, and most importantly, a high enough consistency is achieved so that the process can operate at industrially useful speeds. As used herein, xe2x80x9chigh-speed operationxe2x80x9d or xe2x80x9cindustrially useful speedxe2x80x9d for a tissue machine refers to a machine speed at least as great as any one of the following values or ranges, in feet per minute: 1,000; 1,500; 2,000; 2,500; 3,000; 3,500; 4,000; 4,500; 5,000, 5,500; 6,000; 6,500; 7,000; 8,000; 9,000; 10,000, and a range having an upper and a lower limit of any of the above listed values. Further, molding the sheet at high consistencies significantly improves the ability of the sheet to retain its three-dimensionality and thus also significantly improves the resulting caliper of the sheet. As used herein, the term xe2x80x9ctexturedxe2x80x9d or xe2x80x9cthree-dimensionalxe2x80x9d as applied to the surface of a fabric, felt, or uncalendered paper web, indicates that the surface is not substantially smooth and coplanar. Additionally, the present machine configuration is amenable to incorporating a rush transfer step, which again results in a significant increase in bulk and absorbency relative to the existing wet pressing processes.
Optional steam showers or the like may be employed before the air press to increase the post air press consistency and/or to modify the cross-machine direction moisture profile of the web. Furthermore, higher consistencies may be achieved when machine speeds are relatively low and the dwell time in the air press is relatively high.
The pressure differential across the wet web provided by the air press may be about 25 inches of mercury or greater, such as from about 25 to about 120 inches of mercury, particularly about 35 inches of mercury or greater, such as from about 35 to about 60 inches of mercury, and more particularly from about 40 to about 50 inches of mercury. This may be achieved in part by an air plenum of the air press maintaining a fluid pressure on one side of the wet web of greater than 0 to about 60 pounds per square inch gauge (psig), particularly greater than 0 to about 30 psig, more particularly about 5 psig or greater, such as about 5 to about 30 psig, and more particularly still from about 5 to about 20 psig. The collection device of the air press desirably functions as a vacuum box operating at 0 to about 29 inches of mercury vacuum, particularly 0 to about 25 inches of mercury vacuum, particularly greater than 0 to about 25 inches of mercury vacuum, and more particularly from about 10 to about 20 inches of mercury vacuum, such as about 15 inches of mercury vacuum. The collection device desirably but not necessarily forms an integral seal with the air plenum and draws a vacuum to facilitate its function as a collection device for air and liquid. Both pressure levels within both the air plenum and the collection device are desirably monitored and controlled to predetermined levels.
Significantly, the pressurized fluid used in the air press is sealed from ambient air to create a substantial air flow through the web, which results in the tremendous dewatering capability of the air press. The flow of pressurized fluid through the air press is suitably from about 5 to about 500 standard cubic feet per minute (SCFM) per square inch of open area, particularly about 10 SCFM per square inch of open area or greater, such as from about 10 to about 200 SCFM per square inch of open area, and more particularly about 40 SCFM per square inch of open area or greater, such as from about 40 to about 120 SCFM per square inch of open area. Desirably, of the pressurized fluid supplied to the air plenum, 70 percent or greater, particularly 80 percent or greater, and more particularly 90 percent or greater, is drawn through the wet web into the vacuum box. For purposes of the present invention, the term xe2x80x9cstandard cubic feet per minutexe2x80x9d means cubic feet per minute measured at 14.7 pounds per square inch absolute and 60 degrees Fahrenheit (xc2x0 F.).
The terms xe2x80x9cairxe2x80x9d and xe2x80x9cpressurized fluidxe2x80x9d are used interchangeably herein to refer to any gaseous substance used in the air press to dewater the wet web. The gaseous substance suitably comprises air, steam or the like. Desirably, the pressurized fluid comprises air at ambient temperature, or air heated only by the process of pressurization to a temperature of about 300xc2x0 .F or less, more particularly about 150xc2x0 F. or less.
The wet web is desirably attached to the Yankee dryer or other heated drying cylinder surface in a manner that preserves a substantial portion of the texture imparted by previous treatments, especially the texture imparted by molding on three-dimensional fabrics. The conventional manner used to produce wet-pressed creped paper is inadequate for this purpose, for in that method, a pressure roll is used to dewater the wet web and to uniformly press the wet web into a dense, flat state. For the present invention, the conventional substantially smooth press felt is replaced with a textured material such as a foraminous fabric and desirably a throughdrying fabric. Tissue webs made according to the present method desirably have a bulk after being molded onto the three-dimensional fabric of about 8 cubic centimeters per gram (cc/g) or greater, particularly about 10 cc/g or greater, and more particularly about 12 cc/g or greater, and that bulk is maintained after being pressed onto the heated drying cylinder using the textured foraminous fabric.
For best results, significantly lower pressing pressures can be used as compared to conventional tissue making. Desirably, the zone of maximum load applied to the web should be about 400 psi or less, particularly about 350 psi or less, more particularly about 150 psi or less, such as between about 2 and about 50 psi, and most particularly about 30 psi or less, when averaged across any one-inch square region encompassing the point of maximum pressure. The pressing pressures measured in pounds per lineal inch (pli) at the point of maximum pressure are desirably about 400 pli or less, and particularly about 350 pli or less. Low-pressure application of a three-dimensional web structure onto a heated drying cylinder helps to maintain substantially uniform density in the dried web. Substantially uniform density is promoted by effectively dewatering the web with noncompressive means prior to the Yankee dryer attachment, and by selecting a foraminous fabric to contact the web against the dryer that is relatively free of high, inflexible protrusions that could apply high local pressure to the web. The fabric is desirably treated with an effective amount of a fabric release agent to promote detachment of the web from the fabric once the web contacts the dryer surface.
The absorbency of a tissue sheet may be characterized by its Absorbent Capacity and its Absorbent Rate. As used herein, xe2x80x9cAbsorbent Capacityxe2x80x9d is the maximum amount of distilled water which a sheet can absorb, expressed as grams of water per gram of sample sheet. More specifically, the Absorbent Capacity of a sample sheet can be measured by cutting a 4 inch by 4 inch (101.6 by 101.6 mm) sample of the dry sheet and weighing it to the nearest 0.01 gram. The sample is dropped onto the surface of a room temperature distilled water bath and left in the bath for 3 minutes. The sample is then removed using tongs or tweezers and suspended vertically using a 3-prong clamp to drain excess water. Each sample is allowed to drain for 3 minutes. The sample is then placed in a weighing dish by holding the weighing dish under the sample and releasing the clamp. The wet sample is weighed to the nearest 0.01 gram. The Absorbent Capacity is the wet weight of the sample minus the dry weight (the amount of water absorbed), divided by the dry weight of the sample. At least five representative samples of each product should be tested and the results averaged.
The xe2x80x9cAbsorbent Ratexe2x80x9d is the time it takes for a product to become thoroughly wetted out in distilled water. It is determined by dropping a pad comprised of twenty sheets, each measuring 2.5 inches by 2.5 inches (63.5 by 63.5 mm), onto the surface of a distilled water bath having a temperature of 30xc2x0 C. The elapsed time, in seconds, from the moment the sample hits the water until it is completely wetted (as determined visually) is the Absorbent Rate.
The present method is useful to make a variety of absorbent products, including facial tissue, bath tissue, towels, napkins, wipes, or the like. For purposes of the present invention, the terms xe2x80x9ctissuexe2x80x9d or xe2x80x9ctissue productsxe2x80x9d are used generally to describe such product structures, and the term xe2x80x9ccellulosic webxe2x80x9d is used to broadly refer to webs comprising or consisting of cellulosic fibers regardless of the finished product structure.
Many fiber types may be used for the present invention including hardwood or softwoods, straw, flax, milkweed seed floss fibers, abaca, hemp, kenaf, bagasse, cotton, reed, and the like. All known papermaking fibers may be used, including bleached and unbleached fibers, fibers of natural origin (including wood fiber and other cellulosic fibers, cellulose derivatives, and chemically stiffened or crosslinked fibers) or synthetic fibers (synthetic papermaking fibers include certain forms of fibers made from polypropylene, acrylic, aramids, acetates, and the like), virgin and recovered or recycled fibers, hardwood and softwood, and fibers that have been mechanically pulped (e.g., groundwood), chemically pulped (including but not limited to the kraft and sulfite pulping processes), thermomechanically pulped, chemithermomechanically pulped, and the like. The mixtures of any subset of the above mentioned or related fiber classes may be used. The fibers can be prepared in a multiplicity of ways known to be advantageous in the art. Useful methods of preparing fibers include dispersion to impart curl and improved drying properties, such as disclosed in U.S. Pat. No. 5,348,620 issued Sep. 20, 1994 and U.S. Pat. No. 5,501,768 issued Mar. 26, 1996, both to M. A. Hermans et al.
Chemical additives may be also be used and may be added to the original fibers, to the fibrous slurry or added on the web during or after production. Such additives include opacifiers, pigments, wet strength agents, dry strength agents, softeners, emollients, humectants, viricides, bactericides, buffers, waxes, fluoropolymers, odor control materials and deodorants, zeolites, dyes, fluorescent dyes or whiteners, perfumes, debonders, vegetable and mineral oils, humectants, sizing agents, superabsorbents, surfactants, moisturizers, UV blockers, antibiotic agents, lotions, fungicides, preservatives, aloe-vera extract, vitamin E, or the like. The application of chemical additives need not be uniform, but may vary in location and from side to side in the tissue. Hydrophobic material deposited on a portion of the surface of the web may be used to enhance properties of the web.
The headbox may be stratified to permit production of a multilayered structure from a single headbox jet in the formation of a web. In particular embodiments, the web is produced with a stratified or layered headbox to preferentially deposit shorter fibers on one side of the web for improved softness, with relatively longer fibers on the other side of the web or in an interior layer of a web having three or more layers. The web is desirably formed on an endless loop of foraminous forming fabric which permits drainage of the liquid and partial dewatering of the web.
Numerous features and advantages of the present invention will appear from the following description. In the description, reference is made to the accompanying drawings which illustrate preferred embodiments of the invention. Such embodiments do not represent the full scope of the invention. Reference should therefore be made to the claims herein for interpreting the full scope of the invention.

Method for making tissue sheets on a modified conventional wet-pressed machine


A method for forming a dual oxide thickness trench gate structure for a power MOSFET includes providing a semiconductor substrate; forming a first trench on a top surface of the substrate; forming a first oxide layer in the first trench where the first oxide layer has a first depth from the bottom of the first trench; forming a dielectric spacer along the sidewall of the first trench and on the first oxide layer; etching the first oxide layer exposed by the dielectric spacer to a second depth from the bottom of the first trench using the dielectric spacer as a mask where the second depth is lower than the first depth; removing the dielectric spacer; and forming a second oxide layer along the sidewall of the first trench above the first oxide layer where the second oxide layer has a thickness thinner than the thickness of the first oxide layer.

Power metal-oxide-silicon field-effect transistors (MOSFET) are employed in applications requiring high voltages and high currents. One type of Power MOSFETs uses a trench gate structure where the transistor gate is provided in a vertical trench formed at the surface of the substrate. The trench gate is isolated from the substrate by a gate oxide layer lining the sidewall and the base of the trench. The source and body regions are formed adjacent the trench at the surface of the substrate and the drain region is formed on the opposite surface of the substrate. As thus configured, the channel of the transistor is formed in body region along the vertical sidewall of the trench. Power MOSFETs using a trench gate are sometimes referred to as trench MOSFETs, or trench gate power MOSFETs, or trench-gated vertical power MOSFET.
In some applications, trench gate power MOSFET devices benefit from using a dual oxide thickness trench gate structure. In a dual oxide thickness trench gate structure, the trench gate is formed in a trench lined with a liner oxide layer at a bottom portion of the trench that is thicker than the thin gate oxide layer at the top portion of the trench. FIG. 1 duplicates FIG. 3N of commonly assigned U.S. patent application Ser. No. 13/776,523 and illustrates an example of a dual oxide thickness trench gate structure for a trench gate power MOSFET device. U.S. patent application Ser. No. 13/776,523 is entitled "Termination Trench For Power MOSFET Applications," filed Feb. 25, 2013, and is incorporated herein by reference in its entirety. Conventional fabrication processes for forming the dual oxide thickness trench gate structure involve forming a trench in the silicon substrate to a first depth, forming a nitride spacer on the sidewalls of the trench, and then etching the silicon substrate in the trench further to a second depth using the nitride spacer as a self-aligned mask. Then, the conventional processes perform thermal oxidation to grow the liner oxide layer at the bottom portion of the trench. The nitride spacer is removed and thermal oxidation is performed to grow the gate oxide layer at the top portion of the trench.
Challenges exist in forming the dual oxide thickness trench gate structure. For example, particle debris may become lodged in the bottom of the trench during the second trench etch process. The particle debris inhibits the liner oxidation and causes shorts between the trench gate and the silicon substrate.

Method for forming dual oxide trench gate power MOSFET using oxide filled trench

Alpha and Omega Semiconductor Incorporated


A method for hybrid automatic repeat request HARQ signalling in a communications system is disclosed. The method includes defining, in a communications apparatus, a link-independent HARQ entity for one link direction, wherein the defined entity includes a resource allocation for one or more of forward link and reverse link data, the resource allocation including at least one HARQ process having a process identification, each HARQ process having a unique HARQ identification, a data allocation having a predetermined timing offset with respect to the resource allocation, and a HARQ acknowledgement allocation having a predetermined timing offset with respect to the data allocation, wherein the timing offset of the HARQ acknowledgement with respect to the data allocation is determined in terms of time division duplexing TDD frames and independently of a forward link-reverse link ratio.

The following description of background art may include in-sights, discoveries, understandings or disclosures, or associations together with dis-closures not known to the relevant art prior to the present invention but provided by the invention. Some such contributions of the invention may be specifically pointed out below, whereas other such contributions of the invention will be apparent from their context.
Hybrid automatic repeat request (hybrid ARQ or HARQ) is a combination of high-rate forward error-correcting coding and ARQ error-control for detectable but non-correctable errors. In hybrid ARQ, a code may be used in order to perform forward-error correction and error detection by correcting a subset of errors while relying on ARQ to correct errors that are non-correctable using only redundancy sent in an initial transmission. HARQ in LTE is based on using a stop-and-wait HARQ procedure. When a packet is transmitted from eNode-B, UE decodes it and provides feedback on PUCCH. A similar procedure takes place in uplink side where a packet is transmitted from UE, and eNode-B decodes it and provides feedback on PHICH (physical HARQ indicator channel).

Hybrid automatic repeat request in communications


An integrated circuit package system comprising: forming a finger; forming a die pad adjacent the finger; applying a fill material around the finger and the die pad; forming a cavity in the finger and fill material; and attaching an integrated circuit die over the die pad adjacent the finger with the fill material.

Electronic products have become an integral part of our daily lives. This has created a consistent if not increasing expectation for new features, higher speed, more data, improved portability, etc. These demands have driven the development of electronic technology to reduce size, improve utility, and increase performance of the integrated circuit devices in an ever-increasing range of products such as cell phones, music players, televisions, and automobiles.
Packages of components such as semiconductor circuits, transistors, diodes and other electronic devices must also become smaller and thinner with more functions and connections. In packaging components, the need for connecting leads largely influences package dimensions. Many attempts have been made to create a surface mount type of packaging for semiconductor devices having a lead-less structure in which connecting leads are not needed.
Area array packages such as a ball grid array (BGA) require more materials and processing than more established technologies such as lead frame technology. The BGA package requires a substrate with traces, vias, and solder balls typically preformed for a specific range of integrated circuit device dimensions, input/output (I/O) count, and I/O functions.
Typically, area array packages use a laminate substrate to achieve higher lead counts while lead frame packages use less expensive materials and simpler processes resulting in higher reliability. For example, laminate is not able to withstand pressure cooker tests (PCT) in the same way as lead frame packages. Corrosion tests such as PCT have been a limitation of laminate packages.
Lead frame packaging relies on spacing between connecting leads of a lead frame to be very small in order to connect a device having many signal pins. Width or thickness of each lead should also be reduced but leads bend easily causing unwanted open or short circuits. Unfortunately, package size is often relegated to relatively large dimensions and spacing.
Current high-count lead frame packages require a relatively high number of fabrication steps making fabrication process complicated thereby increasing manufacturing costs. Attempts to provide projected portions at the bottom of a package often require forming metal film on the surface of the projected portions are complicated and costly.
In other attempts, etching processes are required to pattern metal foil for the die pads and leads further complicating manufacturing processes. It is also necessary to use a base apparatus for supporting the metal foil when patterning. This base apparatus is unnecessary after manufacturing the semiconductor integrated circuit device but still increases costs and complexity.
If metal foil is patterned after packaging the semiconductor device, the base apparatus becomes unnecessary. However, since the etching process is typically performed by wet etching, it is necessary to provide water resistant protection for the package including the semiconductor device when the etching is performed. Therefore, these manufacturing processes are also complicated and increase costs.
Yet other attempts require a pattern layer between the frame-like structures and column-like structures. These additional components increase manufacturing complexity and costs. The, number of manufacturing processes steps alone can significantly increase manufacturing processing costs.
Current attempts have many issues often requiring additional components such as metal film, electrodes of metal foil, column-like structures, and pattern layers. These components are pre-designed and manufactured into specific patterns and sizes with additional design and fabrication for different applications. Inventory and manufacturing are complicated and costly.
Thus, a need still remains for improving numbers of leads, compatibility, flexibility, reliability, yield, and manufacturing throughput to control costs and improve performance in systems for integrated circuit packages with isolated leads.
In view of the ever-increasing commercial competitive pressures, along with growing consumer expectations and the diminishing opportunities for meaningful product differentiation in the marketplace, it is critical that answers be found for these problems.
Additionally, the need to save costs, improve efficiencies and performance, and meet competitive pressures, adds an even greater urgency to the critical necessity for finding answers to these problems.
Solutions to these problems have been long sought but prior developments have not taught or suggested any solutions and, thus, solutions to these problems have long eluded those skilled in the art.

This patent is subject to a terminal disclaimer.

Integrated circuit package system with isloated leads


Techniques for calibrating digitally controlled oscillators (DCOs) are disclosed. In an aspect of the disclosure, an initial set of control codes for operating the DCO is determined. A range of output frequencies produced from the initial set is identified. Gaps or instances of overlap are identified in the frequency range. For the overlap case, control codes are removed from the initial set that correspond to the overlap instance to establish a revised set. For the gap case, control codes are added to the initial set for producing frequencies values that fill the gap. An apparatus for performing the same is also disclosed.

1. Field
This disclosure relates generally to the field of electronics, and more specifically, but not exclusively, to digitally controlled oscillators.
2. Background
A digitally controlled oscillator (DCO), sometimes referred to as a numerically controlled oscillator, is an electronic circuit for synthesizing a range of frequencies from a fixed reference clock. The output frequency generated by the DCO at a particular time is a function of the value a digital input or control code. DCOs may be used as frequency synthesizers for generating waveforms for a variety of electronic circuit-based applications. DCOs are being increasingly employed, for example, in the arenas of wireless communications, high resolution imaging, high speed networking, display technology, digital signal processing, and a host of other circuit-intensive areas.
For applications involving conventional wireless communications devices including mobile phones and portable computers, the DCO-produced waveforms may be used to implement functions such as clock and data recovery, carrier wave synthesis, signal encoding/decoding and modulation/demodulation, programmable waveform generation, and the like. Many recent applications involving wireless communications have seen the widespread use of DCOs implemented within digital phase locked loops (DPLLs). Due to its digital nature, the DCO can offer fast switching between output frequencies, high resolution, and operation over a broad frequency spectrum. DCOs may also offer superior noise rejection over conventional circuit techniques by reducing the number of analog circuit components, and reducing or eliminating noise susceptible parameters such as oscillator control voltages, etc.
As the demand for smaller DCOs for fast switching between more granular output frequencies continues to escalate, so too have the problems associated with parasitic circuit values and impedance mismatches for the various circuit elements that make up the DCOs. In practical implementations, linear input codes tend to produce nonlinear output frequencies from DCOs—specifically, gaps or instances of overlap in a plot of output frequency versus input control code.
A need persists in the art for effectively identifying and correcting these instances of nonlinearity in a DCO.

Dynamic calibration techniques for digitally controlled oscillator


A sucker rod connection is disclosed. The sucker rod connection comprises a tapered male member including a plurality of trapezoidal threads, and, a tapered female member also including a plurality of trapezoidal threads, in which the male member is capable of being received in threaded engagement with the female member, wherein the threads of the male member are in flank-to-flank contact, both flanks on each thread, with the threads of the female member, thereby creating diametrical interference between the male and female members preventing disengagement and substantially reducing axial interference between the male and female members.

1. Field of the Invention
Embodiments of the present invention relate to a sucker rod connection, and more particularly, a sucker rod connection with improved fatigue resistance and a method for achieving the same.
2. Description of the Related Art
Sucker rods are rods, typically made of steel or other materials, used to make up the mechanical assembly between the surface and downhole components of a rod pumping system. Sucker rods are conventionally about 25 to 30 ft (about 7 to 9 m) long and have threaded pins at ends of an elongate bar to enable the downhole components to be run and retrieved easily. Sucker rods can be connected with a threaded box or other threaded connection engaging the threaded pin. Typical diameters for sucker rods are ⅝″, ¾″, ⅞″, 1″ and 1⅛″.
The problem of sucker rod failure is particularly severe in 22.22 mm (⅞″) diameter, grade D, API-11B rods. Most failures occur in the rod in the area of the last thread engaged of the pin. In the prior art, for example with a 22.22 mm (⅞″) diameter, grade D, API-11B rod, the thread of the rod is cylindrical, and the diameter of the pin thread is a little smaller than the diameter of the box thread. As shown in FIG. 1A and FIG. 3, only the load flanks of the pin and box come in contact when making up the connection. In other words, there is no diametrical interference, and therefore to prevent disengagement it is necessary to introduce in the connection high deformation between the shoulder of the box and the shoulder of the pin after they come in contact. This deformation creates high axial tension in the pin and compression in the box. This tension in the pin, because of the make up, is added to the cyclical external tension (fatigue) which appears when the rod is working on pumping oil at the well. As a result, very often the tension goes above the resistance allowed of the steel and breaks the pin body in the area of the last engaged thread.

Sucker rod connection with improved fatigue resistance, formed by applying diametrical interference to reduce axial interference


A crystallization mask for laser illumination for converting amorphous silicon into polysilicon is provided, which includes: a plurality of transmissive areas having a plurality of first slits for adjusting energy of the laser illumination passing through the mask; and an opaque area.

(a) Field of the Invention
The present invention relates to a crystallization mask, a crystallization method, and a method of manufacturing a thin film transistor including crystallized semiconductor.
(b) Description of Related Art
A thin film transistor array panel is used for a display device such as a liquid crystal display (LCD) or an organic light emitting display (OLED), which includes a plurality of pixels independently driven by thin film transistors (TFTs).
In general, an LCD includes two panels having field generating electrodes and a liquid crystal layer interposed therebetween. This LCD displays desired images by applying electric field using the electrodes to the liquid crystal layer with dielectric anisotropy and adjusting the strength of the electric field to control the amount of light passing through the panels. In this case, TFTs are used for controlling signals transmitted to the electrodes.
An OLED is a self emissive display device, which displays images by exciting an emissive organic material to emit light. The OLED includes an anode (hole injection electrode), a cathode (electron injection electrode), and an organic light emission layer interposed therebetween. When the holes and the electrons are injected into the light emission layer, they are recombined and pair annihilated with emitting light. The light emission layer further includes an electron transport layer (ETL) and a hole transport layer (HTL) as well as an electron injecting layer (EIL) and a hole injecting layer (HIL) for enhancing the light emission. Each pixel of the OLED includes two TFTs, i.e., a switching TFT and a driving TFT. The current for light emission is driven by the driving TFT and the mount of the current driven the driving TFT is controlled by the data signals from the switching TFT.
The most commonly used TFTs for an LCD adapts amorphous silicon as a semiconductor layer.
An amorphous silicon TFT has mobility of about 0.5 to 1 cm2/Vsec, which is suitable for a switching element of an LCD. However, it is not sufficient for a driving circuit of a display device.
In order to overcome such a problem, an organic EL or a polysilicon TFT LCD using a polysilicon with electron mobility of 20 to 150 cm2/Vsec as a semiconductor layer has been developed. The relatively high electron mobility polysilicon TFT enables to implement a chip in glass technique that a display panel embeds its driving circuits.
In recent years, one of the most widely used methods of forming a polysilicon thin film on a glass substrate with a low melting point is an eximner laser annealing technique. The technique irradiates light with the wavelength, which can be absorbed by amorphous silicon, from an eximer laser into an amorphous silicon layer deposited on a substrate to melt the amorphous silicon layer at 1,400° C., thereby crystallizing the amorphous silicon into polysilicon. The crystal grain has a relatively uniform size ranging about 3,000–5,000, and the crystallization rime is only about 30–200 nanoseconds, which does not damage the glass substrate. However, there are disadvantages that non-uniform grain boundaries decrease the uniformity for electrical characteristics between the TFTs and make it hard to adjust the microstructure of the grams.
To solve these problems, a sequential lateral solidification process capable of adjusting the distribution of the grain boundaries has been developed. The process is based on the fact that the grains of polysilicon at the boundary between a liquid phase region exposed to laser beam and a solid phase region not exposed to laser beam grow in a direction perpendicular to the boundary surface. A mask having a slit pattern is provided, and a laser beam passes through transmittance areas of the mask to completely melt amorphous silicon, thereby producing liquid phase regions arranged in a slit pattern. Thereafter, the melted amorphous silicon cools down to be crystallized, and the crystal growth starts from the boundaries of the solid phase regions not exposed to the laser beam, and proceeds in the directions perpendicular to the boundary surface. The grains stop growing when they encounter each other at the center of the liquid phase region. This process is repeated after moving the slit pattern of the mask in the direction of the grain growth, and thus the sequential lateral solidification covers the whole area. The sizes of the grains can be as much as the widths of the slit pattern.
After the sequential lateral solidification, protrusions of protuberances of about 400–1,000 Å are formed on the surface of the polysilicon layer along the grain boundaries. These causes stress on the boundary surface of a gate insulating layer to be formed on the semiconductor layer. The stress in this process is found to be ten times more than that in the eximer laser annealing, and this results in degrading the characteristics of the TFTs.

Crystallization mask, crystallization method, and method of manufacturing thin film transistor including crystallized semiconductor


The invention relates to a new catalyst composition which is suitable for the polymerization of an olefin and which comprises a reduced transition metal complex and a co-catalyst. The invention is characterized in that the transition metal complex consists of a reduced transition metal, chosen from groups 4-6 of the Periodic Table of the Elements, with a multidentate monoanionic ligand and with two monoanionic ligands. In particular the reduced transition metal is titanium (Ti).

1. Field of the Invention
The invention relates to a catalyst composition which is suitable for the polymerization of an olefin and comprises a reduced transition metal complex and a co-catalyst. The invention also relates to a process for the polymerization of an olefin with such a catalyst composition.
2. Description of the Related Art
Catalyst compositions comprising a reduced transition metal complex and a co-catalyst are known from WO-A-93/19104, which describes complexes of a reduced transition metal of group 4 of the Periodic Table of the Elements, with a bidentate dianionic ligand bonded to it.
The catalyst composition of the present invention is distinguished from that in that the transition metal complex of the present invention consists of a reduced transition metal selected from groups 4-6 of the Periodic Table of the Elements combined with a multidentate monoanionic ligand (X) and two monoanionic ligands (L) as well as, optionally, extra ligands (K).
Such a catalyst composition has not been described before, nor applied in a polymerization of an olefin.

Catalyst composition and process for the polymerization of an olefin