The present invention generally relates to improved methods of assembly of two or more DNA fragments, methods of rapid ligation-independent cloning, and kits for rapid ligation-independent cloning and their uses.

A. DNA Cloning
DNA cloning is the procedure of making copies (or clones) of particular DNA sequences, usually by insertion into a cloning vector and replication into a host organism. Molecular cloning regroups the set of operations needed to assemble and clone recombinant DNA fragments for the purpose of DNA cloning; it usually involves methods to generate DNA fragments and varied strategies to assemble them with a vector that can be further amplified into the host. Traditionally, DNA cloning was made with the use of restriction enzymes (Cohen et al. 1973). Typically, the DNA to clone is cut on each end by a restriction enzyme, the vector is cut by the same enzyme, usually in an area named the multi-cloning site (MCS) and the two fragments are joined together by treatment with a DNA ligase. The use of two restriction enzymes with non-compatible overhangs allows directional cloning in which the DNA fragments is inserted into the vector in only one direction.
Cloning methods were later developed with the availability of the polymerase chain reaction (PCR). PCR enables de novo synthesis of DNA fragments in vitro by exponential amplification of a DNA sequence. A PCR uses a DNA template, two small oligonucleotides called primers whose sequence matches the DNA template on each end of the sequence to amplify, and a series of multistep temperature cycles comprising a denaturation step to separate the two DNA strands, an annealing step where primers find their homologous sequence on DNA, and finally, a step of synthesis or elongation by the means of a DNA polymerase in the presence of dNTPs. If restriction sites are introduced in the primer sequence, PCR fragments can be cloned by traditional restriction enzyme cloning. Alternatively, a blunt-ended PCR product can be cloned directly in an open vector after ligation with the DNA ligase, but not directionally. The use of Taq DNA polymerase often leaves an extra A nucleotide on the 3′ end which limits the blunt-end cloning efficiency. This problem led to the popular T/A cloning method in which a free T overhang generated by a restriction enzyme digestion on the vector conveniently creates a one-base complementary overhang for cloning. All these methods require at some point the use of a DNA ligase to join DNA fragments, even when multiple PCR fragments are combined by Splicing by Overlap Extension PCR (Horton R M et at 1989).
B. Ligation-Independent Cloning
The need for restriction sites and the inherent issues associated with the length of traditional cloning has led to the development of numerous alternate strategies that did not require a DNA ligation step. For purposes of clarity and relevance to this invention, ligation-independent cloning or "LIC", is defined as any cloning method that uses the complementary annealing of sequence-specific single-stranded stretches of DNA located on each end of the DNA fragments for the joining reaction; the stretches must be long enough to hold the DNA assembly together through the transformation process. Note that a few modern cloning methods often use the term, seamless cloning, to be differentiated from the older ligation-independent cloning term, still the event at the source of the DNA joining reaction is the annealing between two complementary stretches of single-stranded DNA "ssDNA" that are physically created during the process. Some authors also use the term, homologous recombination, to highlight the sequence homology between the DNA fragments but the joining reaction is again physically accomplished by the annealing of complementary stretches of ssDNA. The procedure is de facto well-adapted for the cloning of PCR inserts where homologies can be incorporated in the primer sequence Ligation-Independent Polymerase Chain Reaction, "LIC-PCR". In most applications, the stretches of ssDNA are generated by the 3′ to 5′ exonuclease activity found in proof-reading polymerases, such as for example T4 DNA polymerase, but other enzymes have been used with success such as lambda exonuclease, an enzyme with a 5′→3′ exo activity (Tsen 1999). The filling of the gaps left by the annealing of partially overlapping ssDNA tails and ligation per see can occur either in vitro before transformation or in vivo after transformation in the bacterial host with the help of the DNA repair system. It has been shown indeed that the host bacterium fills up the resulting sequence gaps and ligates the construct very efficiently. There are very few by-products, in particular no by-products, resulting from improper ligations. The sequence-dependency of the process makes the cloning very reliable and efficient. The procedure mimics to some extent natural recombination processes used by live cells to repair, mix, and/or exchange DNA molecules.
The first documented report of LIC was made by Aslanidis (Aslanidis et al. 1990). Specially designed vectors with two 12-nucleotide (nt) stretches of DNA containing four nucleotides but one, located on each side of the cloning site were used. Digestion with a 3′→5′ exonuclease in the presence of the complementary nucleotide triphosphate would continue until the first occurrence of the missing base was encountered (event which kicks off the polymerase activity), thus allowing fine control of the stretches of homologous ssDNA (Aslanidis et al. 1990; Haun et al. 1992; Kuijper et al. 1992). In the sequence and ligation-independent cloning or, SLIC method, (Li et al. 2007), all dNTPS were initially excluded to allow sequence-independent overlaps to be created, and dCTP was then added to bring the T4 DNA polymerase to a stall at the first G occurrence and the LIC proceeded as usual.
The minimal length requirement for LIC was found to be 10-nt long (Aslanidis et al. 1994). Improved cloning efficiency was observed between 15-nt and 30-nt (Sharon et al., U.S. Pat. No. 6,372,429), but stretches as long as 100 nt have been reported (Elledge, US Patent Application US 2007/0292954 A1). In a similar situation intermediate between classical cloning and LIC, Stoker et al. were able to apply the Aslanidis method to generate a 2-nt overhang but a final step of DNA ligation was still required for cloning (Stocker et al. 1990).
An alternative method to generate ssDNA tails for cloning PCR products is to mix PCR fragments of unequal length. The method was used in rolling circle PCR, "RCPCR", where both vector and insert are amplified and annealed before transfection (Jones et al. 1990a and 1990b). In this enzyme-free cloning method, Tillet et al. mixed PCR products of different lengths to achieve similar results (Tillet et al. 1999); in a comparable approach, the "mixed-PCR" reaction used multiple nested PCR products (Tachibana et al. 2009). The inverse-PCR, "iPCR", method achieved the same goal by using incomplete PCR products generated towards the end of amplification and found in any PCR reaction (Li et al. 2007).
Many other ways to create ssDNA tails have been described. The use of nicking endonuclease, meaning enzymes that cut only one strand, has been reported (Yang 2010). The use of deoxyuracil residues "dU" incorporated in primers and secondary enzymatic removal by the uracil DNA glycosylase has been reported several times, although for the generation of smaller sticky tails (see e.g. Bitinaite et al. 2007). The presence of abasic sites (sites with no base) induces a stall of the DNA polymerase and, when properly located in primers, creates stretches of ssDNA at the ends of the PCR products; this approach was used in the AS-PCR (autosticky PCR, Gal et al. 1999). The use of primers containing ribonucleotides has been applied to LIC as well (Donahue et al. 2002).
The vaccinia virus DNA polymerase can catalyze in vivo the formation of DNA concateners (Willer et al. 2000). This DNA joining reaction is dependent of the exonuclease activity of the polymerase and is preceded by the formation of complementary ssDNA tails (Hamilton et al. 2007). The reaction can proceed at room temperature without the need for any particular step to inactivate the exonuclease and has been applied to the cloning of DNA fragments (Evans et al. U.S. Pat. No. 7,575,860).
It was shown early after the discovery of LIC that ssDNA stretches can be generated by controlled 3′→5′ exonuclease digestion. Typically, one used the 3′→5′ exonuclease activity of T4 DNA polymerase or of Exonuclease III. The method required a delicate control of the reaction because of the high processivity of those enzymes and variations from batch to batch between enzyme preparations. The last point was reported by Kuijper et al. (1992) who, while proceeding with LIC following the original Aslanidis method, noticed that each lot of T4 DNA polymerase had to be tested, likely for contamination by endonuclease activity. In Hsiao et al. (1993), linearized vectors and PCR inserts were purified and mixed in equal molar amounts, then treated by ExoIII for 30 s to 1 min on ice; after adding TE (Tris/EDTA buffer), the remaining ExoIII was immediately removed by phenol/chloroform extraction. Kaluz et al. (1992) reported a similar approach but only the insert was treated by ExoIII and, following phenol/chloroform extraction, ligated to a cut vector o/n at 16° C.; in this case a ligation step was necessary because of the very short overhangs on the vector side. Li et al. (1997) also used ExoIII followed by phenol/chloroform extraction before annealing and transformation and demonstrated that both 5′ overhangs and gaps can be left for repair by the host bacteria.
A very similar approach using T4 DNA polymerase was published in 1993 (Yang et al. 1993). Following controlled treatment for 2 min at 37° C., the T4 DNA polymerase was inactivated at 70° C. for 10 min. The authors then filled-in the gaps after annealing using again T4 polymerase in the presence of dNTP. It was suggested that the fill-in step may be omitted but the assumption was not verified experimentally. The method was patented under U.S. Pat. No. 5,580,759. The Gibson assembly goes one step further by ligating the DNA assembly before transformation, thus enabling the cloning of very large DNA molecules (Gibson 2011).
The present invention addresses a need in the art for more efficient and faster methods in cloning techniques.

Methods of rapid ligation-independent cloning of DNA and uses thereof


A TV program selection support system selects only programs suiting viewer's preference or necessary for a viewer from a large number of programs to be broadcast and proposes the selected programs to the viewer. The TV program selection support system comprises a program receiver for receiving broadcast TV programs, an EPG receiver for receiving an electronic program table listing TV programs, an EPG storage device for storing an EPG received by the EPG receiver, an operating means to be operated by the viewer to select a program from the stored electronic program table, a program selection support program for determining viewer's view tendency by analyzing the operation made by the viewer, creating an electronic program table on the basis of the view tendency and displaying the created electronic program table.

The present invention relates to a method of supporting a TV (television) viewer for TV program selection and, more particularly, to a method suitable for a viewer to select a desired program among many programs progressively increasing with the increase of TV broadcasting channels caused by the development of digital TV broadcasting techniques, and a system for carrying out the method.
Methods by which TV viewers select TV programs are classified roughly into three groups.
Method 1) This method enables a viewer to obtain information about programs from TV program lists and program information provided in newspapers and magazines or program information heard from other persons, to select a desired program with reference to the information, to set a TV set for broadcasting date and time when the selected program is to be broadcast and a channel through which the selected program is to be broadcast, and to view the selected program. This method is used also to view a desired program by presetting the desired program for recording by a TV or by presetting the desired program for recording by a video recorder.
Method 2) This method enables a viewer to change the channels of a TV set so that programs being broadcast are displayed one after another to enable the viewer to search for a desired program.
Method 3) A broadcasting system using a communication satellite broadcasts an electronic program guide called an EPG. A program list can be viewed on the screen of a TV set through a device having an electronic program guide receiving function. This method enables a viewer to select a desired program by specifying a program name displayed on the screen of the TV set without specifying a channel through which the program of the specified program is broadcast. Techniques relating to this method is mentioned in "Eizou Media Gakkai-shi", Vol. 51, No. 9, pp. 1364(30)–1369(35) (1997). Electronic program guide is able to display only viewer's favorite channels or programs classified by genre.
If digital TV broadcasting becomes prevalent and programs are broadcast through more than one hundred channels, the number of programs which can be viewed by viewers increases. Consequently, the amount of program information provided in newspapers and magazines becomes enormous, and booklets containing program lists and program information will become considerably thick. Under such circumstances, it is very difficult for the viewers to select only necessary information from program information provided in the conventional newspapers and magazines. When selecting a desired program by the method which enables a viewer to change the channels of a TV set so that programs being broadcast are displayed one after another to enable the viewer to search for a desired program, the viewer memorizes the contents of a plurality of desired programs, compares the contents and selects one of the desired programs. It is known that human beings are able to memorize about seven pieces of information for a short period of time. Therefore, it is very difficult for a viewer to memorize the contents of successively viewed programs when the channels increases.
The method 3) using EPG is able to solve the problem of the thick booklet but the same cannot solve problem of difficulty in selecting a desired program from many programs. Even if the number of channels is as small as ten channels or below through which ground waves can be received by TV sets, many people have regretful experiences of having failed to notice program lists, of obtaining information about programs after programs have been broadcast, of failing in viewing programs and of forgetting recording programs.


The instant invention relates to novel surfactant-free, multiphase sunscreen compositions that provide protection from the sun, have a unique visual appeal, and provide skin conditioning and moisturization. In a two-phase embodiment of the instant invention, the compositions are comprised of (1) a first layer comprising a high-density ester and sunscreen, and (2) a second aqueous layer, which is usually the top layer. In a three-phase embodiment of the instant invention, the compositions are comprised of (1) a first layer comprising a high-density ester and and sunscreen, (2) a second aqueous layer, and (3) a third oily layer. The high-density ester layer usually has a specific gravity that is greater than that of the aqueous layer and the aqueous layer usually has a specific gravity that is greater than the oily layer. In preferred embodiments, each phase is substantially clear and has a volume approximately equal to that of the other phase(s). The phases disperse upon mixing and separate over time after mixing. The phases may be colored differently to enhance visual appeal. In some embodiments, emulsified boundary layer(s) form between the phases and constitute third or fourth phases.

One portion of the solar spectrum comprises wavelengths of electromagnetic energy which range between about 290 and 3,000 nanometers (nm). This range may be divided into different regions, namely: (1) the ultraviolet region (290–400 nm), (2) the visible region (400–760 nm) and (3) the near-infrared region (>760 nm). The ultraviolet region has, moreover, been arbitrarily divided into three bands, referred to as the UVA, UVB and UVC bands.
The UVB band extends from 290 to 320 nm. It is the principal cause of the sunburn reaction and it is also the most effective in stimulating the tanning reaction in the skin. UVC radiation (200–290 nm) from the sun does not reach the surface of the earth, although one can encounter radiation in this range from artificial sources such as germicidal lamps and high and low pressure mercury arc lamps. For purposes of the present invention, however, protection against UVC radiation is generally not a major concern, i.e., in contrast to the dangers posed by UVA and UVB radiation. The UVA band, which extends from 320–400 nm, can also cause the tanning reaction. UVA radiation can also cause sunburns, but its capacity to do so is less than that of UVB radiation.
The amount of UVA radiation exposure, however, is increasing. This is due to the fact that most sunscreens effectively block only UVB radiation. As stated above, UVB radiation is more capable than UVA radiation of causing the tanning and burning reactions. Therefore, if one is using a sunscreen that blocks UVB radiation he/she will tend to stay in the sun for an extended period of time because the immediate effects of the sun tan/bum are not evident. The problem is that UVA is still penetrating the skin and although it is not causing any immediately obvious effects, it is causing long-term damage. Long-term hazards of ultraviolet radiation include premature aging of the skin. This condition is characterized by wrinkling and yellowing of the skin, along with other physical changes such as cracking, telangiectasis (spider vessels), solar keratoses (growths), ecchymoses (subcutaneous hemorrhagic lesions), and loss of elasticity (sagging).
In recent years, it has been well documented that UVA radiation, like UVB radiation, is harmful to the skin. In fact, current data reveal that solar radiation containing these wavelengths (A and B) is a contributing cause of skin cancer, which presently accounts for 30–40% of all new cancers each year. In the United States alone, 500,000 new cases of skin cancer will be reported this year and the number is expected to keep rising in the future. UVA radiation has been shown to promote skin cancer by inhibiting enzymes that repair cells damaged by UVB radiation. UVA radiation also penetrates more deeply into the skin than UVB radiation and causes changes in blood vessels and premature aging of the skin, thus adding to the damage produced by UVB rays. The goal of any sunscreen should thus be to protect the user from both UVA and UVB radiation with a minimum of side effects.
The "SPF" (Sun Protection Factor) is recognized as the ratio of the irradiation time required to elicit a minimum erythemal reaction (sunburn) on sunscreen protected skin using a solar simulator, to the irradiation time required to elicit the same minimum erythemal reaction (sunburn) on unprotected skin. This test is conducted under clinical conditions according to the procedure described in the Proposed Monograph for Sunscreen Containing Drug Products (hereafter referred to as the Proposed Monograph) published by the U.S. Food and Drug Administration (FDA) in the U.S. Federal Register, Vol. 43, Aug. 25, 1978, Part 2, pages 38206–38269, which is incorporated herein by reference. As used herein, the term "SPF" or Sun Protection Factor is defined in accordance with the definitions in the Proposed Monograph. This same publication also describes the clinical testing procedure mandated for determining whether sunscreen products are waterproof, water resistant and sweatproof. The labeled SPF values are generally recognized as being between 2 and 50. This is not meant to imply that SPF values greater than 50 are unachievable given the previous formulation technology. However, the amounts of sunscreen agents needed to achieve such high SPF values are usually cost prohibitive given current formulation technologies. The concentration of sunscreen agents needed to satisfy a waterproof designation are particularly high, because some of the agents are washed away in the test that measures SPF for a waterproof composition.
In general, the SPF number approximately corresponds to the multiple of time during which the properly applied sunscreen will prevent obvious reddening of the skin, over the exposure time that causes unprotected skin to exhibit reddening. Thus, a person should be able to remain in the sun without visible effects for eight times the usual unprotected duration, if an SPF 8 sunscreen formulation has been properly applied. Of course, the duration of unprotected exposure, which produces a visible effect on the skin, varies from one individual to another, due to differences in their skin cells. Currently popular are high-SPF "sunblocker" products, having SPF values of at least 30.
A sunscreen works on the surface of the skin to absorb UV radiation so that the harmful rays never enter the skin. Commercially available sunscreen products contain from about 3 to about 26% of one or more UV absorbing chemicals. When applied to the surface of the skin as a thin film, these chemicals act as a filter to diminish the penetration of UV radiation to the cells of the epidermis. These sunscreens are typically applied in a cream, oil, lotion, alcohol or gel vehicle and they are usually colorless because they do not contain any visible light-absorbing chemicals. The most widely used organic-based sunscreens contain, for example, paraminobenzoic acid (PABA), PABA esters (glyceryl PABA), amyldimethyl PABA and octyldimethyl PABA), benzophenones (oxybenzone and sulisobenzone), cinnamates (octylmethoxy cinnamate and cinoxate), salicylates (homomethyl salicylate), anthranilates such as menthyl anthranilate, 2-ethylhexyl-2-cyano-3,3-diphenyl acrylate, 2-phenyl benzimidazole-5-sulfonic acid, digalloyl trioleate, 3-(4-methyl benzylidene) camphor, 4-isopropyl dibenzoyl methane, butyl methoxy dibenzoyl methane, 2-ethyl-2-cyano-3,3′-diphenyl acrylate.
Common sun care products sold in today's market include oil-in-water emulsions incorporating stearic acid neutralized with triethanolaminc. The SPF values of such emulsions range from 2 to 50, and they commonly include ethylhexyl methoxycinnamate as the sunscreen agent. As the SPF of these formulations increases, they commonly contain ethylhexyl salicylate, homosalate, octocrylene and/or oxybenzone in addition to the ethylhexyl methoxycinnamate mentioned above. Alternatively, padimate O can be used in place of the ethylhexyl methoxycinnamate or the salicylates mentioned above. Dioxybenzone, avobenzone or menthyl anthranilate can be used in place of oxybenzone. If the product does not claim to be substantive to the skin (i.e., waterproof or water resistant), trolamine salicylate or DEA methoxycinnamate can be used in place of (or in combination with) the ethylhexyl methoxycinnamate, ethylhexyl salicylate or homosalate. Additionally, sulisobenzone may be used in such non-substantive formulations in place of oxybenzone. The Proposed Monograph lists 21 active ingredients that can be used individually or in combinations to achieve the desired product SPF.
U.S. Pat. No. 4,917,882 ("'882 patent") discloses a gel-type sunscreen composition comprising about 1 and about 30 percent of sunscreen agent, between about 5 and about 25 percent polyethylene, and between about 20 and about 95 percent of a benzoate ester. The benzoate ester is important to the composition of the '882 patent because it provides a translucent, non-oily feeling, anhydrous vehicle which is well suited for carrying the sunscreen agents. In particular, the patent notes that benzoate esters do not interfere with the UV absorption of typical sunscreen agents and that compounds such as mineral oil have been found to shift the absorbance curve of agents such as Padimate O, thereby reducing their ability to absorb UV radiation in the erythemal region.
Sunscreen compositions in the form of creams and lotions are two-phase systems in which one of the phases is finely and uniformly dispersed within the other to form an emulsion. Mixing the two phases with an appropriate surfactant emulsifier, which also functions to stabilize the emulsion and initially makes the dispersion. The sun screening ingredients are usually solubilized in the oil phase, which is, most commonly, the internal or dispersed phase. However, after application and prolonged exposure of the skin to water, the surfactants actually facilitate the emulsifier removal of the product from the skin by causing the oils to re-emulsify.
Several approaches have been taken in an effort to solve this problem. One solution is to resort to water in oil emulsions. Because this type of emulsion is usually not sufficiently water soluble to dissolve or disperse in water, it therefore has little ability to re-emulsify oily material into water. Another technique used to reduce the re-emulsification of the sunscreen's internal "oily phase" is to use emulsifiers that lose their ability to emulsify once they have been applied to the skin. These are typified by the "polymeric" surfactants that rely upon a "sphere of hydration" to establish and maintain their water solubility. Once the hydration sphere is lost (due to drying when the product is applied to the skin), the polymeric surfactant loses its ability to emulsify and the oil phase along with the dissolved sunscreens stay on the skin.
Another way to eliminate re-emulsification is to simply not include any surfactants in the formulation. Sunscreen oils take this approach and do not show significant reductions in sun protection factors following bathing. However, sunscreen or sun tanning oils are considered to have an unpleasant, "greasy" feel and they can have an unfavorably high cost of goods as they are made entirely of oils. Creams and lotions, on the other hand, can contain 70% to 80% water and therefore have a concomitantly lower production cost, but they suffer from the re-emulsification problem described above.
The need exists, therefore, for multiphase, high SPF sunscreen compositions that provide adequate and prolonged protection against both UVB and UVA radiation even upon extended exposure to water. Ideally, such compositions would have a low production cost and would not evoke any unpleasant sensation upon application to the skin. Further, the need exists for multiphase sunscreen products in which the various phases are visibly distinct prior to application, thereby enhancing the cosmetic appeal of the products.


A pressure control system varies a parameter of a gas flowing out of the well to artificially generate a pressure value at a fluid mover. The fluid mover receives fluid from a conduit such as a dip tube positioned in the well. The system may also include a flow control device controlling a gas flow out of the well and a controller controlling the flow control device using information relating to at least one wellbore parameter.

1. Field of the Disclosure
The disclosure herein relates generally to the methods and devices for controlling gas production.
2. Background of the Art
Hydrocarbon gas is usually recovered using a well drilled into a formation having a gas reservoir. A gas well may have a complex geometry that includes vertical sections and deviated sections, at least some of which intersect a gas-producing zone, or "pay zone." Water is often produced along with the gas in a pay zone. Because the hydrostatic pressure associated with produced water can impair the rate of gas production, it is usually desirable to control the amount of water residing in a pay zone or other section of a well. However, the borehole of the well may have geometry or trajectory that prevents a fluid mover, such as a pump, from being located in the well to efficiently remove accumulated water.
The present disclosure is directed to methods, devices, and system for removing water from a section of the well using a remotely situated fluid mover.

Gas production using a pump and dip tube


A method of preventing network denial of service attacks by early discard of out-of-order segments comprises creating a reassembly queue for a connection between a first network node and a second network node, wherein the connection has been established based on a transport-layer network protocol, the reassembly queue having a size based on a buffer size of an input interface with which the connection is associated. As out-of-order data segments arrive on the connection, and before other processing of the segments, whether the reassembly queue is full is determined, and the out-of-order segments are discarded if the reassembly queue is full. The size of the reassembly queue is automatically changed in response to one or more changes in any of network conditions and device resources.

The approaches described in this section could be pursued, but are not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Transmission Control Protocol (TCP) as described in IETF RFC 793 defines transport-layer messages that network nodes may communicate to achieve guaranteed data delivery and implement flow control. TCP data packets include a header carrying a segment sequence number that a receiver can use to determine whether the receiver has received all segments from a sender. Valid segments must have a sequence number falling in a changeable range defined as the receiver's sliding receive window. Different implementations can use receive windows of different sizes.
Varying network conditions can cause loss or delay of segments in a stream of segments that a sender sends a receiver. When a TCP implementation at the receiver receives segments bearing a sequence number higher than the highest previously acknowledged segment, the receiver stores the newly received segments in a reassembly queue for later processing after earlier missing segments arrive.
When too many out-of-order segments arrive on a TCP connection, and the receive window of a TCP implementation is large, then the TCP implementation is vulnerable to an attack consisting of a flood of spoofed segments. The receive window of an application might be large when an application uses large data records, or in applications that traverse satellite links or links in other so-called "long fat networks" in which delays are longer or more drops occur than with other kinds of links. Receive window scaling is described in V. Jacobson et al., "TCP Extensions for High Performance," IETF RFC 1323 (1992).
Since an incoming segment is more likely to be accepted if the receive window is large, vulnerability increases with window size. If the number of spoofed and received out-of-order segments is excessively large, then the reassembly queue can overflow. Alternatively, if a TCP implementation allocates more memory for the reassembly queue as more out-of-order segments arrive and overflow approaches, then eventually the TCP implementation may run out of memory. The result would be resource exhaustion and a successful denial of service (DOS) attack.
Further, in certain approaches in which segments are placed in the reassembly queue by writing a pointer to the segment in an interface input queue, overflow of the reassembly queue also may cause resource exhaustion at the interface input queue. This condition may trigger slow-start approaches in protocols such as UDP that are using the same interface but not associated with the problem condition. Resource starvation of all protocols that are using the interface may occur.
The same problem may arise when too many genuine out-of-order segments arrive. In that case, for efficient management of resources such as packet memory, then queuing too many segments is undesirable. However, it may be difficult to determine whether received segments are genuine or spoofed.
Known TCP stacks do not limit the size of the TCP reassembly queue. Implementing a hard-coded limit on the reassembly queue is inefficient, especially for applications that must use a large receive window size, or for applications in which the receive window is typically an order of magnitude larger than the normal window size. U.S. application Ser. No. 10/815,218, filed Mar. 30, 2004, entitled "Preventing network data injection attacks using duplicate-ACK and reassembly gap approaches," of Anantha Ramaiah et al., describes how to discard the "fake" data in the re-assembly queue.

Preventing network denial of service attacks by early discard of out-of-order segments


A method and system for compositing a plurality of three-dimensional Sub-Images by examining the Depth values of the Pixels corresponding to same spatial location in each Sub-Image and compositing the content of the Pixel having the greatest Depth value. The Depth values are divided into two or more binary Segments, where the bit length of the Segments is determined according to their level of significance. In a first step, the numerical values of the Segments having the same level of Significance are simultaneously compared, and accordingly a group designating the Depth values which the numerical value of their Most Significant Segment is the greatest is determined, and a Grade is evaluated for the Least Significant Segments indicating their numerical size in comparison with the numerical value of the other Segments of the same level of significance. In a second step, the Grades of the Segments of the Depth values which corresponds to the group are compared, and Depth value indications are removed from the group if their Grade is less than the highest Grade which corresponds to another Depth values in the group. The second step is repeated until the last set of Segments is reached or until a single Depth values is designated by the group.

As with many types of information processing implementations, there is a ongoing effort to improve performance of computer graphics rendering. One of the attractive attempts to improve rendering performance is based on using multiple graphic processing units (GPUs) harnessed together to render in parallel a single scene.
There are three predominant methods for rendering graphic data with multiple GPUs. These include Time Domain Composition, in which each GPU renders the next successive frame, Screen Space Composition, in which each GPU renders a subset of the pixels of each frame, and Scene based Composition, in which each GPU renders a subset of the database.
In Time Domain Composition each GPU renders the next successive frame. A major disadvantage of this method is in having each GPU rendering an entire frame. Thus, the speed at which each frame is rendered is limited to the rendering rate of a single GPU. While multiple GPUs enable a higher frame rate, a delay can be imparted (i.e., impairing latency) in Time Domain Composition applications in the response time of the system to user's input. These delays typically occurs since at any given time only one GPU is engaged in displaying a rendered frame, while all the other GPUs are in the process of rendering one of a series of frames in a sequence. In order to maintain a steady frame rate, the system delays acting on the user's input until the specific GPU that first received the user's input cycles through the sequence and is again engaged in displaying its rendered frame. In practical applications, this condition serves to limit the number of GPUs that are used in a system.
Another difficulty associated with Time Domain Composition applications is related to the large data sets that each GPU should be able to access, since in these applications each GPU should be able to gain access to the entire data used for the image rendering. This is typically achieved by maintaining multiple copies of large data sets in order to prevent possible conflicts due to multiple attempts to access a single copy.
Screen Space Composition applications have a similar problem in the processing of large data sets, since each GPU must examine the entire data base to determine which graphic elements fall within its part of the screen. The system latency in this case is equivalent to the time required for rendering a single frame by a single GPU.
The Scene Compsition methods, to which the present invention relates, excludes the aforementioned latency problems, the requirement of maintaining multiple copies of data sets, and of the problems involved in handling the entire database by each GPU.
The Scene Composition methods well suits applications requiring the rendering of a huge amount of geometrical data. Typically these are CAD applications, and comparable visual simulation applications, considered as "viewers," meaning that the data have been pre-designed such that their three-dimensional positions in space are not under the interactive control of the user. However, the user does have interactive control over the viewer's position, the direction of view, and the scale of the graphic data. The user also may have control over the selection of a subset of the data and the method by which it is rendered. This includes manipulating the effects of image lighting, coloration, transparency and other visual characteristics of the underlying data.
In CAD applications, the data tends to be very complex, as it usually consists of massive amount of geometry entities at the display list or vertex array. Therefore the construction time of a single frame tends to be very long (e.g., typically 0.5 sec for 20 million polygons), which in result slows down the overall system response.
Scene Composition (e.g. object based decomposition) methods are based on the distribution of data subsets among multiple GPUs. The data subsets are rendered in the GPU pipeline, and converted to Frame Buffer (FB) of fragments (sub-image pixels). The multiple FB's sub-images have to be merged to generate the final image to be displayed. As shown in FIG. 1, for each pixel in the X/Y plane of the final image there are various possible values corresponding to different image depths presented by the FBs' sub-images.
Each GPU produces at most one pixel 12 at each screen's (X/Y) coordinate. This composed pixel 12 is a result of the removal of hidden surfaces and the shading and color blending needed for effectuating transparency. Each of the pixels 12 generated by the GPUs holds a different depth measure (Z-value), which have to be resolved for the highest Z (the closest to the viewer). Only one pixel is finally allowed through. The merging of the sub-image of each FB is the result of determining which value (10) from the various possible pixels values 12 provided by the FBs represents the closest point that is visible in viewer's perspective. However, the merging of the partial scene data to one single raster, still poses a performance bottleneck in the prior art.
The level of parallelism in the prior art is limited, due to the inadequacies in the composition performance of multiple rasters. The composition of two rasters is usually performed by Z-buffering, which is a hardware technique for performing hidden surface elimination. In the conventional methods of the prior art Z-buffering allows merging of only two rasters at a time.
Conventional hardware compositing techniques, as examplifed in FIG. 2A, are typically based on an iterative collating process of pairs of rasters (S. Molner "Combining Z-buffer Engines for Higher-Speed Rendering," Eurographics, 1988), or on pipelined techniques (J. Eyes at al. "PixelFlow: The Realization," ACM Siggraph, 1997). The merging of these techniques is carried out within log2 R steps, of S stages, wherein R is the number of rendering GPUs. In the collating case, the time needed to accomplish comparison between two depth measures at each such comparator (MX) is log2 Z, where Z is the depth domain of the scene. E.g. for typical depth buffers with 24 bits per pixel, the comparison between two Z-buffers is typically performed in 24 time clocks.
Since in the prior art techniques the merging of only two Z-buffers is allowed at a time, composition of multiple rasters is made in a hierarchical fashion. The complexity of these composition structures is O(log2 R), making the performance highly effected by R, the number of graphic pipelines. For growing values of R the compositing time exceeds the allocated time slot for real time animation. In practical applications, this condition serves to limit the number of GPUs that are used in a system. FIG. 2B shows the theoretical improvement of performance by increasing parallelism. The composition time grows by the factor of the complexity, O(log2 R). The aggregated time starts increasing at (e.g.) 16 pipelines. Obviously, In this case there is no advantage in increasing the level of parallelism beyond 16.
Software techniques are usually based on compositing the output of R GPUs by utilizing P general purpose processors (E. Reinhard and C. Hansen "A Comparison of Parallel Compositing Techniques on Shared Memory Architectures," Eurographics Workshop on Parallel Graphics and Visualisation, Girona, 2000). However, these solutions typically requires utilizing (i) binary swap, (ii) parallel pipeline, and (iii) shared memory compositor, which significantly increase the complexity and cost of such implemetations.
The most efficient implementation among the software techniques is the Shared Memory Compositor method (known also as "Direct Send" on distributed memory architectures). In this method the computation effort for rendering the sub-images is increased by utilizing additional GPUs (renderers), as shown in the block diagram of FIG. 3A and the pseudo code shown in FIG. 3B. In the system illustrated in FIG. 3A, 2 compositors (CPUs, p0 and p1) are operating concurrently on the same sub-images, which are generated by 3 renderers (GPUs, B0, B1, and B2). The computation task distributed between the CPUs, each performing composition of one half of the same image. It is well-known that for any given number of GPUs one can speed up the compositing by increasing the number of parallel compositors.
However, increased number of renderers slows down the performance severely. The complexity of this method is O(N*R/P) where N is the number of pixels in a raster (image), R is the number of GPUs, and P is the number of compositing units (CPUs, Pi). The compositing process in this technique is completed within R−1 iterations. In the implementation of this technique on SGI's Origin 2000 Supercomputer the compositing was carried out utilizing CPUs. The results of the compositing performed by this system are shown in FIG. 4. FIG. 4 demonstrates the overhead of this method, the compositing time required for this system is over 6 times the time required for the rendering.
All the methods described above have not yet provided satisfactory solutions to the problems of the prior art methods for compositing large quantities of sub-images data into one image.
It is an object of the present invention to provide a method and system for rendering in parallel a plurality of sub-image frames within a close to real time viewing.
It is another object of the present invention to provide a method and system for concurrently composing large amounts of sub-image data into a single image.
It is a further object of the present invention to provide a method and system which substantially reduce the amount of time requires for composing sub-image data into a single image.
It is a still another object of the present invention to provide a method and apparatus for concurrently composing large amounts of sub-image data into a single image that can be implemented efficiently as a semiconductor based device.
It is a still further object of the present invention to provide a method and apparatus for composing sub-image data based on presenting a competition between the multiple sources of the sub-image data.
Other objects and advantages of the invention will become apparent as the description proceeds.

Method and system for compositing three-dimensional graphics images using associative decision mechanism


A split roof lining and datum scheme includes first, second and third roof lining assemblies. The first and second roof lining assemblies are aligned and directly connected to a roof installation of a vehicle using alignment features mated with datums in the roof installation. The third roof lining assembly is aligned and directly connected with the first and second roof lining assemblies using alignment features mated with datums in the first and second roof lining assemblies. The third roof lining assembly is not directly connected to the roof installation. Cover assemblies, optionally including light sources, cover interfaces between the first and third roof lining assemblies and between the second and third roof lining assemblies.

A roof lining covers an interior surface of a roof of a vehicle. Such a roof lining can be of a single piece or a multi-piece construction. In multi-piece roof linings, a joint between the multiple pieces may run a full width of the vehicle and is visible to occupants of the vehicle.


A wireless device establishes a data session with a data call, and a data connection is set up for the data session. The wireless device may receive or originate a voice call while the data session is dormant, exchange traffic data for the voice call, and perform handoff between base station controllers (BSCs), if needed, during the voice call. Upon termination of the voice call, the wireless device determines whether it has moved to a new packet zone during the voice call. This may be the case if the wireless device was handed off between BSCs located in different packet zones. If the wireless device has moved to a new packet zone, then the data connection is updated, e.g., by sending to the current serving BSC an origination message indicating no data to send. The network entities perform appropriate actions to update the data connection for the wireless device.

I. Field
The present disclosure relates generally to communication, and more specifically to techniques for maintaining a data connection during a dormant data session with a wireless communication network.
II. Background
Wireless communication networks are widely deployed to provide various communication services such as voice, packet data, broadcast, messaging, and so on. These wireless networks may be multiple-access networks capable of supporting communication with multiple users by sharing the available system resources. Examples of such multiple-access networks include Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, and Orthogonal Frequency Division Multiple Access (OFDMA) networks.
A wireless device (e.g., a cellular phone) may originate a packet data call to establish a data session with a wireless network. As part of the data call setup, a data connection is established among network entities that will serve the wireless device for the data session, which are called serving network entities. Thereafter, the wireless device may send or receive packet data via the serving network entities. The data session may be sporadically active for only a small portion of the time and may be dormant for much of the time.
The wireless device may roam while the data session is dormant and may move out of the coverage of the serving network entities. In some instances, the wireless device may not be able to update the data connection to new network entities that can serve the wireless device for the data session. This may be the case, for example, if the wireless device has an ongoing voice call and is not permitted to send signaling during the voice call to update the data connection for the data session. If the data connection is not updated and the wireless network thereafter has packet data to send to the wireless device, then the wireless device may miss the packet data because the data connection is erroneous.
There is therefore a need in the art for techniques to maintain a data connection during a dormant data session.

Maintaining a data connection during a dormant data session with a wireless communication network


An electric power steering apparatus includes a controller for controlling power assist of an electric motor so as to reduce a manual steering force required of the driver. The controller includes two closed control loops, one operating on the basis of a steering torque and the other on the basis of a differential value of the steering torque. The second closed control loop includes a differential torque compensator for compensating for the differentiated steering torque in such a manner as to increase the proportion of an assist torque developed in accordance with the change of the steering torque while keeping a desired degree of stability of operation of the steering system.

1. Field of the Invention
The present invention relates to an electric power steering apparatus which provides power assist of an electric motor directly to a steering system so as to reduce necessary steering power to be applied by the driver.
2. Description of the Related Art
FIG. 1 of the accompanying drawings diagrammatically shows the general construction of an electric power steering apparatus of the type concerned.
The electric power steering apparatus 1 includes an electric motor 10 disposed in a steering system of the vehicle, and a controlling unit or controller 20 for controlling power assist of the electric motor 10 so as to reduce a manual steering effort or power required of the driver.
A steering wheel 2 of the vehicle is firmly connected to one end of a steering shaft 3, the opposite end of the steering shaft 3 being operatively connected through a pair of universal joints 4a, 4b to a pinion gear 6 of a rack-and-pinion mechanism 5. The rack-and-pinion mechanism 5 includes a rack shaft 7 having formed on its outside surface a row of rack teeth 7a meshing with the pinion gear 6. By means of the rack-and-pinion mechanism 5 formed jointly by the pinion gear 6 and the rack teeth 7a, rotary motion of the pinion gear 6 is translated into axial reciprocating motion of the rack shaft 7. The rack shaft 7 is connected at its opposite ends to steerable front wheels 9, 9 via a pair of tie rods 8, 8, respectively.
With this arrangement, when the steering wheel 2 is steered or turned in one direction, the front wheels 9 are caused to pivot or swing in the same direction via the rack-and-pinion mechanism 5 and the tie rods 8, thereby changing the direction of motion of the vehicle.
In order to reduce necessary steering power to be applied by the driver, the electric motor 10 for providing a steering assist torque (power assist) is disposed coaxially with the rack shaft 7 in such a manner that rotational output power of the electric motor 10 is converted via a ball screw mechanism 11 into an axial thrusting force acting on the rack shaft 7. The ball screw mechanism 11 is composed of a nut 12 connected to a rotor of the electric motor 10 for co-rotation therewith, and a screw shaft 7b formed on a part of the rack shaft 7 and threaded with the nut 12. With this arrangement, a rotational force of the nut 12 is converted via the screw shaft 7b into an axial thrusting force of the rack shaft 7. Since the steering assist torque generated by the electric motor 10 is thus converted into the axial thrusting force of the rack shaft 7, a manual steering force required of the driver to steer the front wheels 9 can be reduced.
A steering torque sensor 18 detects a manual steering torque T acting on the pinion gear 6 and generates a steering torque signal 18a indicative of the detected steering torque T. The steering torque signal 18a is supplied to the controller 20. The controller 20 generates a motor drive signal 20a on the basis of the torque signal 18a, so as to control output power of the electric motor 10 according to the motor drive signal 20a.
FIG. 2 is a block diagram showing a typical known example of the controller 20. As shown in this figure, the controller 20 generally comprises an assist torque control section 30 and a motor drive section 40. The assist torque control section 30 determines a target assist torque based on the torque signal 18a from the steering torque sensor 18 and generates a target assist torque signal 30a. The motor drive section 40 generates a motor drive signal 20a based on the target assist torque signal 30a.
The assist torque control section 30 includes a steering torque compensator 31, a first target assist torque determiner 32, a steering torque differentiator 33, a second target assist torque determiner 34, and an adding means or adder 35.
The steering torque compensator 31 undertakes compensation of the frequency characteristics of the steering torque signal 18a and generates a compensated steering torque signal 31a. To this end, the steering torque compensator 31 has a frequency characteristic so set as to stabilize operation of the steering system.
The target assist torque determiner 32 generates a first assist torque signal 32a based on the compensated steering torque signal 31a. The first assist torque signal 32a is a signal corresponding to a drive current (including the polarity thereof) of the electric motor 10 which is required for the electric motor 10 to generate a first target assist torque. The first target assist torque signal 32a may be a signal corresponding to a drive voltage of the electric motor 10 which is required for the electric motor 10 to generate the first target assist torque.
The first target assist torque determiner 32 has a steering torque vs. first target assist torque conversion table which is prepared to output a value of the first target assist torque with respect to the input of a value of the compensated steering torque. The first target assist torque determiner 32 is designed to set the first target assist torque value to be zero when the absolute value of the compensated steering torque value is smaller than a preset dead zone threshold. Alternatively, when the compensated steering torque value is greater than the preset dead zone threshold, the first target assist torque determiner 32 operates to output a first target assist torque value proportional to the compensated steering torque value. The first target assist torque determiner 32 controls the first target assist torque value so as not to exceed a preset first target assist torque upper limit even when the compensated steering torque value becomes large.
The steering torque differentiator 33 determines the amount of change in the steering torque signal 18a per unit time and outputs the determined change of the steering torque signal 18a as a differential torque signal 33a.
The second target assist torque determiner 34 outputs a second target assist torque signal 34a based on the differential torque signal 33a. The second target assist torque signal 34a is a signal corresponding to a drive current (including the polarity thereof) of the electric motor 10 which is required for the electric motor 10 to generate the second target assist torque. The second target assist torque signal 34a may be a signal corresponding to a drive voltage of the electric motor 10 which is required for the electric motor 10 to generate the second target assist torque.
The second target assist torque determiner 34 has a differential torque vs. second target assist torque conversion table which is prepared to output a value of the second target assist torque with respect to the input of a differential torque value. The second target assist torque determiner 34 is designed to set the second target assist torque value to be zero when the absolute value of the differential torque value is smaller than a preset dead zone threshold. The dead zone threshold of the second target assist torque determiner 34 is set to be smaller than the dead zone threshold of the first target assist torque determiner 32. When the differential torque value is greater than the preset dead zone threshold, the second target assist torque determiner 34 operates to output a second target assist torque value proportional to the differential torque value. The second target assist torque determiner 34 controls the second target assist torque value so as not to exceed a preset second target assist torque upper limit even when the compensated steering torque value becomes large.
The adder 35 operates to add together the first target assist torque signal 32a and the second target assist torque 32a and output the result of the adding operation as the aforesaid target assist torque signal 30a.
The motor drive section 40 is comprised of a deviation calculating circuit 41, a PID (proportional-integral-derivative control) circuit 42, and a drive circuit 43.
The electric motor 10 is equipped with a current detector (not shown) which detects a current being actually supplied to the electric motor 10 and outputs a drive current signal 10a corresponding to the detected motor current. The drive current signal 10a is fed back to the deviation calculating circuit 41 of the motor drive section 40.
The deviation calculating circuit 41 determines a deviation between the target assist torque signal 30a (i.e., a signal corresponding to a current to be supplied to the electric motor 10 to generate the target assist torque) and the drive current signal 10a, and it outputs a deviation signal 41a.
The PID circuit 42 is designed to perform specific computing operations, such as proportion, integration and differentiation on the basis of the deviation signal 41a and to output a PID control output signal 42a to the drive circuit 43.
The drive circuit 43 generates, on the basis on the PID control output signal 42a, a motor drive signal 20a and provides it to the electric motor 10 so as to supply a drive current (or a drive voltage) to the electric motor 10.
The conventional controller 20 of the foregoing construction operates to set both a first target assist torque in accordance with a steering force exerted by the driver and detected by the steering torque sensor 18, and a second target assist torque in accordance with the change of the steering force, and to control, on the basis of a target assist torque obtained by adding together the first target assist torque and the second target assist torque, an assist torque to be provided from the electric motor 10.
In the conventional controller 20, the steering torque compensator 31 is disposed immediately upstream of the first target assist torque determiner 32 so as to stabilize the operation of the steering system. Rotational power of the electric motor 10 is fed back to the steering torque sensor 18 via the ball screw mechanism 11 and the rack shaft 7. The electric motor 10, the ball screw mechanism 11, the rack shaft 7, the steering torque sensor 18, the steering torque compensator 31, the first target assist torque determiner 32, the adder 35 and motor driving section 40 are operatively connected together in the order named and jointly form a first closed control loop. In the first closed control loop, the steering torque compensator 31 undertakes compensation of the frequency characteristics in an effort to stabilize control operation of the first closed control loop.
However, when the compensated steering torque signal 31a supplied as an output from the steering torque compensator 31 has such a small level which is included in a dead zone of the first target assist torque determiner 32 (namely, smaller than the dead zone threshold), the first target assist torque signal 32a supplied from the first target assist torque determiner 32 is fixed to the value of 0 (zero). In this condition, the first closed control loop (starting from the steering torque sensor 18, then passing successively through the steering torque compensator 31, the first target assist torque determiner 32 and the motor drive section 40, and finally returning to the steering torque sensor 18), i.e., a closed loop containing the first target assist torque determiner 32 cannot undertake a prescribed closed loop control action. In other words, when the output level of the steering torque compensator 31 is in the dead zone of the first target assist torque determiner 32, the frequency characteristics compensation performed by the steering torque compensator 31 becomes totally ineffective.
There is another or a second closed loop in the controller 20, which loop starts from the steering torque sensor 18, then passes successively through the steering torque differentiator 33, the second target assist torque determiner 34, the adder 35, the motor driving section 40 and the electric motor 10, and finally returns to the steering torque sensor 18 (i.e., a closed loop including the second target assist torque determiner 34). Even when the absolute value of a steering torque value is small to such an extent as to belong to the dead zone of the first target assist torque determiner 32, if the amount of a change in the steering torque per unit time (represented by a differential torque signal 33a supplied from the steering torque differentiator 33) exceeds the dead zone threshold of the second target assist torque determiner 34, an assist torque based on the change of the steering torque will be supplied. However, the second closed loop including the second target assist torque determiner 34 does not have any means for adjusting or compensating the frequency characteristics to stabilize the control operation of the second closed loop. Accordingly, if a control operation of the controller 20 based only on the second closed loop including the second target assist torque determiner 34 is performed, the control operation tends to become unstable.
In the conventional controller 20, although an attempt was made to increase the proportion of the second target assist torque to the first target assist torque so as to provide a light feel to steering maneuvers, the result was unsatisfactory in that when steering is taken on a road having a low tire ground-contact coefficency (such as a snow-clad road) and hence requires only a small manual steering force (i.e., when the level of an output from the steering torque compensator 31 is in the dead zone of the first target assist torque determiner 32), partly due to a small frictional force acting between the road surface and the tires, and partly due to an insufficient control-loop stabilizing operation of the steering torque compensator 31, the steering system becomes unstable and sometimes causes unpleasant vibrations of the steering wheel 2. Thus, the conventional controller 20 has a limited capability of increasing the proportion of the second target assist torque to the first target assist torque in an effect to improve the comfortableness of steering maneuvers without deteriorating the stability of control operation of the steering system.


Provided is a voltage level shift circuit including: a first voltage level shift circuit formed of a P-channel enhancement type transistor (M1) and an N-channel depletion type MOS transistor (M3); and a second voltage level shift circuit formed of a P-channel enhancement type transistor (M2) and an N-channel depletion type MOS transistor (M4). In the voltage level shift circuit, a cascode circuit using an N-channel depletion type transistor (M5) is serially connected to the first voltage level shift circuit, a cascode circuit using an N-channel depletion type transistor (M6) is serially connected to the second voltage level shift circuit, and a unit for complementarily controlling bias voltages of the respective cascode circuits. As a result, an output signal of the voltage level shift circuit connected to an input of a differential amplifier circuit, for expanding an input voltage range of a signal, is not affected by fluctuations in power supply voltage.

1. Field of the Invention
The present invention relates to a voltage level shift circuit and a semiconductor integrated circuit including a differential amplifier circuit which uses the voltage level shift circuit. More particularly, the present invention relates to a voltage level shift circuit with improved relative accuracy and improved power supply rejection ratio and to a semiconductor integrated circuit using the voltage level shift circuit.
2. Description of the Related Art
A technique to add a voltage level shift circuit to an input stage of a differential amplifier circuit or the like to expand an input voltage range of the differential amplifier circuit is conventionally widely used (see, for example, JP 05-22054 A).
Such a voltage level shift circuit is, for example, in a constant voltage circuit illustrated in FIG. 6A, inserted on an input side of an error amplifier (differential amplifier circuit) 101 to be used as a voltage level shift circuit 100 for expanding an input voltage range of the error amplifier (differential amplifier circuit) 101 in some cases. In such a constant voltage circuit, when a low voltage (for example, 315 mV) is outputted as an output DCout, in order to decrease the number of divided resistors R1 and R2 connected to a power MOS transistor 31 for power output, it is preferable to monitor as a low voltage as possible by a voltage feedback signal VFB and to set a reference voltage Vref outputted from a reference voltage circuit 30 to 315 mV.
However, as the error amplifier 101, a differential amplifier circuit using MOS transistors as illustrated in FIG. 6B is often used. In the differential amplifier circuit (error amplifier) 101, a drain-source voltage (Vds) of an N-channel enhancement type MOS transistor M11 is about 200 mV, while a gate-source voltage (Ggs) of an N-channel enhancement type MOS transistor M9 is about 400 mV, and thus, an input signal of 600 mV or more is necessary at input terminals IN+ and IN− of the differential amplifier circuit. Therefore, it is necessary to shift the level of the direct current potential of a reference voltage Vref (signal of about 315 mV) and a voltage feedback signal VFB by the voltage level shift circuit 100 to be inputted to the differential amplifier circuit (error amplifier) 101 as a signal of 600 mV or more.
In this way, when the level of the direct current potential of an input signal is shifted in a positive direction by a voltage level shift circuit, a source follower circuit using a P-channel enhancement type MOS transistor with a constant current circuit being a load is sometimes used. For example, FIG. 7 illustrates an exemplary conventional source follower circuit (see Behzad Razavi, "Design of Analog CMOS Integrated Circuits", Maruzen Co., Ltd., Mar. 30, 2003, pp. 82-91).
The conventional source follower circuit uses a constant current source formed of a bias voltage source 14 for outputting a constant voltage with a power supply voltage being the reference and a P-channel enhancement type MOS transistor M32 as a load of a P-channel enhancement type transistor M31. Here, the relationship between a direct current potential Vi of the input voltage and a direct current potential Vo of the output voltage is:Vo=Vi+VTP+(1/K)1/2,  (1)where a current supplied by the constant current source is I. Here, VTP and K are a threshold voltage and a conductance coefficient, respectively, of the P-channel enhancement type transistor M31 which operates as a source follower.
It is to be noted that there are conventional reference voltage circuits and an electronic device (see JP 2003-295957 A). However, an object of the conventional reference voltage circuits is to decrease the difference in voltage applied to the reference voltage circuits and to make smaller the difference between the output voltages of the respective reference voltage circuits. The conventional reference voltage circuits are not related to the above-mentioned voltage level shift circuit (source follower circuit).
When the voltage level shift circuit illustrated in FIG. 7 is used at the input of a differential amplifier circuit, at least two voltage level shift circuits having the same characteristics are necessary. However, when a plurality of voltage level shift circuits having the same characteristics are formed, there is a problem in that, due to uneven accuracy in manufacture, it is difficult to maintain the same difference between the input potential and the output potential of the respective voltage level shift circuits.
Further, in a voltage level shift circuit illustrated in FIG. 7, due to fluctuations in the power supply voltage, source-drain voltage of a transistor M32 for supplying constant current fluctuates, and thus, there is a problem in that the power supply rejection ratio is deteriorated due to channel length modulation effect.
Further, the voltage level shift circuit illustrated in FIG. 7 has a problem in that, because fluctuations on the side of the power supply voltage are caused at an output terminal through a parasitic capacitance between a substrate and a drain terminal of the P-channel enhancement type transistor M32 used as the load, the power supply rejection ratio at a low frequency (<1 kHz) is deteriorated.

Voltage level shift circuit and semiconductor integrated circuit


A high-power magnetron assembly includes a high-power magnetron and a compact magnetic field generator. The high-power magnetron includes a cathode configured to emit electrons in response to receiving a supply of voltage from a power supply. The high-power magnetron includes an anode configured to concentrically surround the cathode and to attract the emitted electrons across an interaction region between the cathode and the anode. The compact magnetic field generator includes a plurality of permanent magnets including: a cathode magnet that has a longitudinal axis of symmetry annularly and that is surrounded by the cathode and disposed within the magnetron; and an anode magnet configured to annularly surround an outer perimeter of the magnetron. An arrangement of the plurality of permanent magnets concentrically about the longitudinal axis of symmetry forms a specified magnetic field within the interaction region that bounds the electrons emitted within the interaction region.

Magnetrons require a strong and nearly uniform external magnetic field within the interaction region between the cathode and anode structures. Various magnetic-field generator solutions meet these requirements. One solution includes two "Helmholtz-like" coils or a solenoid, which can generate a nearly uniform field in a central region between the coils containing the magnetron. A second solution includes a "U-shaped" bar of iron with a coil at the bottom of the "U" and the magnetron placed between ends of the "U." A third solution applies to a low-power magnetron, where external "U-shaped" permanent magnets are used. The permanent magnets according to the third solution are relatively large and heavy because a large amount of magnetic material is necessary to create the "U-shaped" permanent magnets. Specifically, the magnetron cathode and anode (the main magnetron structures) are very small, so the permanent magnets are located external to these main magnetron structures. The permanent magnets must be relatively large and heavy in order to generate the required magnetic field in the small interior region between the cathode and anode because the permanent magnets are located at some distance from the primary electron-beam interaction region in the gap between the cathode and anode.
Both of the magnetic-field generator techniques described above that use coils to generate the magnetic field required for high-powered magnetrons are large and heavy and require an external power source for the coils. The volume and weight associated with the power source adds additional size and weight to the magnetic-field generator/magnetron system. High-power magnetrons that have a high duty factor operation may require a method of cooling the magnet coils. A cooling system for the magnet coil adds additional size and weight to the magnetron. Many potential applications for a magnetron cannot tolerate the weight or size of these magnetic-field generator techniques.

Compact magnet design for high-power magnetrons


There is disclosed a flow control valve which regulates a flow rate by determining a stop position of a piston by contact in an opened state, and which enables remote and high-precision flow rate regulation. In a closed state, an urging force of a return spring acts on a piston, bringing a diaphragm into close contact with a valve seat. In this state, when compressed air is supplied into a pilot chamber, moving the piston, the diaphragm is brought out of contact with the valve seat. Then, the piston comes into contact with a nut and the diaphragm is stopped providing a fixed clearance between the diaphragm and the valve seat. An opened state is established. Of course, the nut can be moved to any desired position by means of a serve motor or the like, so that a position at which the piston comes into contact with the nut can be changed.

1. Field of the Invention
The present invention relates to a flow control valve which is changed to and held in an opened state by pressure of compressed air against an urging force of a spring and more particularly to a flow control valve for use in a semiconductor manufacturing device.
2. Description of Related Art
As one of conventional flow control valves, for example, there is a flow control valve disclosed in Japanese unexamined patent publication No. 7(1995)-253170. FIG. 4 is a sectional view of such flow control valve 100. This flow control valve 100 has an under body 120 with an inlet port 121 and an outlet port 122 formed on either side. An intermediate body 130 formed with a first operation port 131 is secured on the under body 120. An upper body 140 formed with a second operation port 141 and attached with an adjustment screw 142 is secured on the intermediate body 130. Thus, the outer shape of the whole flow control valve 100 is determined.
The under body 120 is centrally provided with an annular valve seat 101 in addition to the inlet port 121 formed at a right side in the figure and the outlet port 122 formed at a left side in the figure. An inside A of the valve seat 101 is communicated with the inlet port 121, whereas an outside B of the valve seat 101 is communicated with the outlet port 122. When a valve body 102 is brought into contact with the valve seat 101, communication between the inlet port 121 and the outlet port 122 is interrupted. When the valve body 102 is brought out of contact with the valve seat 101, the communication between both ports 121 and 122 is allowed.
The intermediate body 130 is a substantially cylindrical member secured on the under body 120 at a center area thereof. The intermediate body 130 is formed with the first operation port 131 and further internally formed with a small-diameter cylinder 132 and a large-diameter cylinder 133. In the intermediate body 130, a substantially columnar piston 150 is fit to be slidable up and down. The piston 150 has a central large-diameter portion 151, a lower small-diameter portion 152 provided under the large-diameter portion 151, and an upper small-diameter portion 153 provided above the large-diameter portion 151. The large-diameter portion 151 is air-tightly engaged in the large-diameter cylinder 133. The lower small-diameter portion 152 is air-tightly engaged in the small-cylinder 132. A lower surface 154 of the large-diameter portion 151 and the intermediate body 130 define a first operation chamber 134. The first operation port 131 of the intermediate body 130 opens into the first operation chamber 134. Through the first operation port 131, air pressure is applied to or released from the first operation chamber 134. When the air pressure is applied to the first operation chamber 134, the piston 150 is pushed up.
The valve body 102 is attached to a lower end of the lower small-diameter portion 152 of the piston 150. The circumferential portion of the valve body 102 forms a diaphragm 156 of which the peripheral edge is sandwiched between the under body 120 and the intermediate body 130. The valve body 102, which is movable in conjunction with the vertical movement of the piston 150, is brought out of contact or into contact with the valve seat 101 of the under body 120. When the valve body 102 is brought into contact with the valve seat 101, communication between the inlet port 121 and the outlet port 122 is interrupted. When the valve body 102 is brought out of contact with the valve seat 101, the communication between both ports 121 and 122 is allowed.
The upper body 140 is a substantially cylindrical member secured on the intermediate body 130. The upper body 140 is centrally formed with a through hole 143 in addition to the second operation port 141. The upper small-diameter portion 153 of the piston 150 is engaged in the hole 143 of the upper body 140. The upper surface 155 of the large-diameter portion 151, the intermediate body 130, and the upper body 140 define a second operation chamber 144. The second operation port 141 of the upper body 140 opens into the second operation chamber 144. Through the second operation port 141, air pressure is applied to or released from the second operation chamber 144. When the air pressure is applied to the second operation chamber 144, the piston 150 is pushed down. The upper body 140 is formed with a spring groove 145. A return spring 146 is located between the upper surface 155 of the piston 150 and the spring groove 145. The return spring 146 urges the piston 150 downward.
An upper half of the hole 143 of the upper body 140 is formed with screw threads. The adjustment screw 142 is mounted in this portion. The adjustment screw 142 has a lower end 147 which restricts upward movement of the piston 150. Changing of the height of the lower end 147 by turning of the adjustment screw 142 allows changes of a stop position of the piston 150, thereby adjusting a clearance between the valve body 102 and the valve seat 101 at a valve opening time. It is to be noted that a lock nut 148 may be used to hold the adjustment screw 142 against inadvertent movement.
The operation of the flow control valve 100 having the above structure will be explained below. The flow control valve 100 is operated by the application of air pressure to the first operation port 131 or the second operation port 141. A means for supplying the air pressure may be anything, for example, a compressed-air cylinder and an air-pressure pump.
The state where no air pressure is applied to both the first operation port 131 and second operation port 141 is first considered. In this state, the piston 150 receives the urging force of only the return spring 146. The piston 150 is therefore moved downward until the valve 102 attached at a lower end of the piston 150 comes into contact with the valve seat 101. In this state, the valve body 102 is held in contact with the valve seat 101, interrupting communication between the inlet port 121 and the outlet port 122, the flow control valve 100 is closed.
When the air pressure is applied to the first operation port 131, the first operation chamber 134 of the flow control valve 100 is increased in pressure. This pushes the piston 150 upward against the urging force of the return spring 146 until the upper end of the piston 150 comes into contact with the lower end 147 of the adjustment screw 142, and then the piston 150 is stopped. The valve body 102 is accordingly moved together with the piston 150, providing a clearance between the valve seat 101 and the valve body 102, thereby allowing the communication between the inlet port 121 and the outlet port 122. Thus, the flow control valve 100 becomes opened.
In this state, when the adjustment screw 142 is operated to change the position of the lower end 147, the stop position of the piston 150 is changed. The clearance between the valve seat 101 and the valve body 102 is adjusted to control a flow rate during an opened state of the flow control valve 100.
When supply of the air pressure to the first operation port 131 is stopped and the pressure of the first operation chamber 134 is released, the flow control valve 100 is placed in a closed state again by the urging force of the return spring 146. At that time, air pressure is applied to the second operation port 141, the pressure in the second operation chamber 144 becomes high. This pressure assists the urging force of the return spring 146 to push the piston 150 downward. A valve closing operation is further ensured.
The control of a flow rate by means of the flow control valve 100 in FIG. 4 is however performed by manual turning of the adjustment screw 142 to change the lower end 147 of the screw 142 with which the upper end of the piston 150 comes into contact, changing the stop position of the piston 150 in the opened state. Accordingly, it could not be conducted by remote and high-precision control.
Particularly, the control of a flow rate by remote and high-precision control is required for a semiconductor manufacturing device. On this account, the flow control valve 100 shown in FIG. 4 would be unusable in the semiconductor manufacturing device.
FIG. 5 shows the flow control valve 100 of FIG. 4 additionally attached with an electro-pneumatic regulator 160 which controls a normally-closed proportional intake valve 161 and a normally-closed proportional discharge valve 162 through a control substrate 163. In this flow control valve 100 of FIG. 5, air pressure is applied to or released from the first operation port 131 through the electro-pneumatic regulator 160 to bring the valve into the opened state or the closed state. Thus, when the normally-closed proportional intake valve 161 is opened and simultaneously the normally-closed discharge proportion valve 162 is closed, air pressure is supplied and applied to the first operation chamber 134, thereby bringing the valve into the opened state and holding it in that state. Upon de-energization in this state, however, the normally-closed proportional intake valve 161 and the normally-closed proportional discharge valve 162 are closed, but the air pressure in the first operation chamber 134 remains retained. Depending on the state or the case, the opened state is sustained. This may continuously cause an outflow of a fluid to be controlled.
Especially, if the outflow of the controlled fluid is continued during de-energization, the flow control valve 100 of FIG. 5 would be unusable in the semiconductor manufacturing device which requires accurate flow control.


An electroluminescent light source included as a sheet-like structure as part of headliner in a vehicle. The electroluminescent light source is arranged under an outer layer of fabric, as well as under a layer of foam and a layer of nonwoven textile material. The electroluminescent light source lacks a dedicated housing for containing the electroluminescent light source, which allows for the headliner to maintain a flat and uniform surface that is undisturbed by the inclusion of the electroluminescent light source. When the electroluminescent light source is activated, the emitted light has sufficient brightness to shine through the various layers of the headliner to illuminate the interior of the vehicle.

Vehicles typically include a metal roof over a passenger compartment of the vehicle. As seen in FIG. 1, the interior surface of the roof is often lined with a headliner 2, consisting of an underlying non-woven textile layer 4 arranged closest to the metal roof, which textile layer 4 is covered by a foam layer 6, which is covered by a fabric layer 8 defining an exposed surface 10 of the headliner 2 that is visible to occupants inside the passenger compartment of the vehicle.
Interior illumination of the passenger compartment is typically accomplished using lighting fixtures including a light bulb arranged in a housing. The housing is attached to the interior surface of the roof of the vehicle, so that light emitted by the light bulb is directed down from the roof to illuminate the passenger compartment of the vehicle. This type of lighting fixture provides light that emanates from a single location (i.e. from the lighting fixture), and thus may present uneven lighting throughout the passenger compartment. This type of light fixture also includes the use of the housing, which presents a bulky protrusion on the interior surface of the roof of the vehicle, and thus presents a non-uniform appearance in relation to the headliner 2 that may be undesirable.


A semiconductor device used for a semiconductor relay includes: a first diode; a second diode; an electric field shield film for covering the second semiconductor island region, where the second diode is formed; and a wiring for electrically connecting the first diode to the second diode. The wiring is arranged so as to cross above a silicon oxide film surrounding the second semiconductor island region. The electric field shield film is positioned below the wiring, and has a cutout portion in an overlapping region which overlaps the wiring. By forming the cutout portion, end portions of the electric field shield film is arranged to be shifted. Therefore, formation of a deep concave portion which is based on a concave portion on the silicon oxide film and a step of the electric field shield film over the entire width of the wiring can be prevented, and the disconnection of the wiring can be prevented.

A semiconductor relay (optical semiconductor relay device) is one type of a relay having no movable contact (which is a non-contact relay), and is a relay that inputs/outputs signals by an electronic circuit using a semiconductor. As such a semiconductor relay, for example, a so-called solid state relay is cited. In the solid state relay, non-contact signal transmission is achieved by signal transmission using an optical signal and an electric signal in an electrically-insulated space between a light-emitting element such as a photo coupler and a semiconductor element (semiconductor device) such as a thyristor, triac, diode, and transistor.
For example, Patent Document 1 (Japanese Patent Application Laid-Open Publication No. H04-303973) disclose a technique of covering surfaces of a photovoltaic diode and a control circuit with a polycrystalline semiconductor layer in a photo acceptance element for the solid state relay.


An embodiment is a method and apparatus for ultrasonic contact imaging. A thin-film transistor (TFT) array is deposited on a substrate. A receiver having a plurality of receiver elements is deposited on the TFT array to receive a received signal. A transmitter adjacent to the receiver generates a transmit signal at an ultrasonic frequency. The transmit signal is reflected from a surface to produce a reflected signal. The received signal is a superposition of the transmit signal and the reflected signal as result of interference. The received signal is representative of differences in acoustic impedances across the surface.

Incoherent C-mode ultrasound detectors have been used for high resolution surface and contact imaging in scanned single element devices, similar to acoustic microscopes, and also 2D arrays. However, all of these detectors use a pulse-echo methodology to collect reflectivity information from the surface of interest. The complexity of the electronics and acoustic structures needed to scale these devices to large areas becomes complex, impractical, or expensive.
Techniques for large-area ultrasound contact imaging have a number of disadvantages. High resolution, C-mode, contact/surface images may be acquired by scanning a highly focused ultrasound transducer over a surface, similar to an acoustic microscope. The focused transducer operates in pulse-echo mode, in which an ultrasound pulse or tone burst is transmitted to the surface and the received reflected response is peak detected at the appropriate time/range gate associated with the surface. Since scanning a single transducer is very time consuming, there has been development of large-area 2D arrays that collect a whole image plane synchronously. However, because the surface of interest is typically a large distance, greater than many wavelengths, away from the receiver face, large apertures are needed to maintain high resolution at the imaging surface. In the single element transducer system, this means that the scan step size and resolution at the focal point is often much smaller than the diameter of the single-element transducer. Thus, simply tiling single element transducers to produce a large-area array is not only difficult, but also will not provide the pixel density needed for large-area, 2D, ultrasound contact imaging.
U.S. Pat. No. 5,456,256 and U.S. Patent Application Number 2007/0258628 A1 describe two-dimensional (2D) array approaches that use dynamic focusing of smaller-sized elements. However, the electronics required to time delay and phase each element are complex and difficult to match over a large number of elements. This approach also requires the distribution of common reference signals, which is a challenge over a large area. Because of the complexity of these circuits, they prohibit the use of polysilicon thin film transistors (TFTs) and other low-cost, large-area electronics. Thus, the electronics requirements for this approach are prohibitively complex and expensive when scaled to large-areas.
Acoustic structures, such as lenses and waveguides, may be used to maintain high resolution for pulse-echo contact imaging with incoherent arrays. U.S. Pat. Nos. 5,483,963 and 6,552,841 describe large lenses used to focus ultrasound from the image plane onto an incoherent focal plane detector. In this approach, the resolution is limited by the aperture of the lens, which is not easily scalable to arbitrarily large areas. In addition, the lens structure requires large separations between the focal plane array, the lens, and the image plane; this limits the overall size of the final device.
U.S. Patent Application Numbers 2008/0258580 A1 and 2008/0219098 describe waveguide structures used to prevent ultrasound spreading to maintain resolution at the image plane. However, this structure suffers from difficulties in manufacturing and performance. To achieve the density and resolution needed, the acoustic waveguides often need to be spaced very close together (on the order of or smaller than a wavelength). Because the cores are spaced so closely together, the cladding layers are very thin and allow crosstalk between neighboring cores that degrades lateral resolution. In addition, fabricating the waveguide plates and aligning them with an array becomes increasingly difficult for large areas.
Pulse-echo structures and methods of ultrasound contact imaging are not scalable to large-area, incoherent devices capable of high-resolution, low-cost imaging.


A fabrication method of three-dimensional microstructures is to fabricate a real 3D microstructure. First, a substrate is coated with an anti-reflection layer to absorb reflected exposure light, and then the anti-reflection layer is overlaid with a first thick photoresist. After having been fully exposed by a first photo mask, a predetermined exposure depth of the first thick photoresist is achieved by a second photo mask and dosage-controlled UV exposure. If the unexposed areas of the first thick photoresist are released during a development step, a single-layer microstructure is created. Inversely, a multi-layered microstructure can be obtained simply by repeating the process described above. After all layers are laminated on the substrate, all unexposed areas of the all thick photoresist layers are released and connected to each other during a development step.

1. Field of the Invention
The present invention relates to a fabrication method of three-dimensional (3D) microstructure, and more particularly, to a semiconductor process employing a thick photoresist by controlling exposure dosage to form a microstructure on a substrate.
2. Description of the Related Art
In recent years, microstructure devices have been developed for biochemistry, sensor science and pharmaceutics, and also have given rise to the advent of various fabrication techniques to fabricate microstructures made from various materials.
Embedded micro channels are generally used for microstructure devices to distribute and store micro fluid, and find applications in areas such as reagents, pharmaceuticals or inkjet printheads. There are at least four major methods that have been reported that use thick photoresist, such as SU-8 resist, to fabricate embedded micro channel structures. All the methods are superior to other non-mentioned micromachining techniques, such as excimer laser micromachining, especially in respect to costs and applicability.
As shown in FIGS. 1(a)–1(c), the first method discloses that a substrate 11 is overlaid with a filling material 13 and SU-8 layers 12 and 14 to define embedded micro channels. And then the filling material 13 is released from therein to obtain micro channels embedded in the substrate 11. UV light 15 is employed as an exposure source on SU-8 layers 12 and 14. However, this method must apply many different materials to finish one layer of embedded channel. In particular, the filling material 13 is different from the SU-8 layers 12, and negative effects in succeeding steps arise from their mismatching characteristics.
FIGS. 2(a)–2(c) illustrate the fabrication process of the second method. A whole SU-8 layer coated on the substrate 21 is directly overlaid with a metal mask 24 after exposed areas 22 and unexposed areas 23 arise from UV exposure. In the succeeding step, the metal mask 24 is coated with another SU-8 layer 25, and the SU-8 layer 25 is exposed to UV light 26. Therefore, the unexposed areas 23 of the lower SU-8 layer are not exposed to UV light 26 yet due to the metal mask 24. The micro channel can be released after the unexposed areas 23 are developed. Unfortunately, the metal mask 24 is a thin film liable to have cracks thereon. The cracks will cause a next stacked layer, such as SU-8 layer 25, failures. The root cause of the cracks is from the elevated temperature during an evaporation step or a succeeding baking step. Furthermore, the microstructure is also caused damage by the removal of the metal mask 24 thereafter.
The third method laminates a Riston film (dry film) 33 by a roller 34 on a SU-8 layer 32 formed on a substrate 31 to obtain micro channels, as show in FIGS. 3(a)–3(b). The adhesion uniformity problem between them is a serious concern during the laminating step. As shown in FIGS. 4(a)–4(c), a microstructure is formed on a substrate 41 by utilizing proton beam 44 to partially expose a SU-8 layer. The entire depth of SU-8 a layer can be fully exposed by a proton beam 44 with higher intensity. Therefore, the areas covered with a photo mask 46 are unexposed areas 43, the other areas are fully exposed areas 42. Under partial exposure of a proton beam 45 with lower intensity, the upper portions of the unexposed areas 43 become new exposed areas 42, and the lower portions of the unexposed areas 43 remain unexposed. In the fourth method, the proton beam 45 may be an elegant approach for dosage control on exposure, but not a popular source for common use.
In summary, the traditional methods for a microstructure either use more than two materials and a tedious process, or costly facilities like the proton beam, and are not simple enough for the fabrication of stacked channels.

Fabrication method of a three-dimensional microstructure


A method for managing data distribution within a networked computing environment, the method including receiving one or more tasks and associated task priorities. The method includes determining a current resource allocation for a plurality of computing devices within the networked computing environment. The method includes determining, based, at least in part, on the received task priorities and the current resource allocation, at least one of the plurality of computing devices to assign as a source computing device, and sending at least one of the one or more tasks to the at least one source computing device.

The deployment of large amounts of information and data, such as virtual machine images, text documents, presentations, and software updates, in the educational delivery field is necessary but often inefficient and unreliable. Data deployment includes getting new software or hardware up and running properly in its environment, including installation, configuration, running, testing, and making necessary changes. In computer-based training sessions, the data is not always deployed to the client or student computing devices on time or deployed accurately, and this problem only increases when a large number of computing devices are included and large amounts of data need to be deployed. Deployment of information between computing devices can also be done through peer-to-peer networks. Peer-to-peer networking is a distributed application architecture that partitions tasks or work loads between peers. Peers are able to make a portion of their resources available to other networked devices without central coordination by servers or stable hosts.

Managing data distribution to networked client computing devices

International Business Machines Corporation