The present invention provides a method and an improved apparatus for removing gas bubbles from a reaction chamber comprising a flexible layer removably affixed to a substrate layer having a multiplicity of oligonucleotide binding sites disposed thereon, in which biological reactions are performed. The invention specifically relates to methods and apparatus for removing gas bubbles from a reaction chamber wherein target molecules contained in a sample fluid are reacted with probe molecules immobilized on a substrate having an array of oligonucleotide binding sites. The arrays are covered with a flexible, gas permeable layer that permits mixing of the sample fluid on the biochip and removal of gas bubbles from the fluid by use of a means for facilitating diffusion of gas bubbles across the flexible, gas permeable layer.

1. Field of the Invention
The present invention relates to an apparatus for performing biological reactions on a substrate surface and a method for removing gas bubbles from the apparatus. Specifically, the invention relates to an apparatus having a flexible, gas permeable layer affixed to a substrate layer with an adhesive, wherein the flexible, gas permeable layer, the adhesive and the substrate layer enclose a reaction chamber, and a means for facilitating diffusion across the flexible, gas permeable layer. The diffusion-facilitating means creates a pressure gradient or concentration gradient across the flexible, gas permeable layer, thereby increasing the rate of diffusion of gas molecules from the reaction chamber across the flexible, gas permeable layer.
2. Description of the Prior Art
Recent advances in molecular biology have provided the opportunity to identify pathogens, diagnose disease states, and perform forensic determinations using gene sequences specific for the desired purpose. This explosion of genetic information has created a need for high-capacity assays and equipment for performing molecular biological assays. Most urgently, there is a need to miniaturize, automate, standardize and simplify such assays. While these assays were originally developed in research laboratories working with purified products and performed by highly skilled individuals, adapting these procedures to clinical uses, such as diagnostics, forensics and other applications, has produced the need for equipment and methods that allow less-skilled operators to effectively perform the assays under higher capacity, less stringent assay conditions.
Existing technology utilizes the binding of molecules contained within a biologically reactive sample fluid, hereinafter referred to as target molecules, onto molecules contained within biologically reactive sites, hereinafter referred to as probe molecules. The primary enabler of this technology is an apparatus commonly referred to as a biochip, which comprises one or more ordered microscopic arrays (xe2x80x9cmicroarraysxe2x80x9d) of biologically reactive sites immobilized on the surface of a substrate. A biologically reactive site can be created by dispensing a small volume of a fluid containing a biological reagent onto a discrete location on the surface of a substrate, also commonly referred to as spotting. To enhance immobilization of probe molecules, biochips can include a 2-dimensional array of 3-dimensional polymeric anchoring structures (for example, polyacrylamide gel pads) attached to the surface of the substrate. Probe molecules such as oligonucleotides are covalently attached to polyacrylamide-anchoring structures by forming amide, ester or disulfide bonds between the biomolecule and a derivatized polymer comprising the cognate chemical group. Covalent attachment of probe molecules to such polymeric anchoring structures is usually performed after polymerization and chemical cross-linking of the polymer to the substrate is completed.
Biochips are advantageously used to perform biological reactions on the surface thereof. Existing apparatus for performing biological reactions on a substrate surface, however, are deficient in that they either require unacceptably large volumes of sample fluid to operate properly, cannot accommodate substrates as large as or larger than a conventional microscope slide, cannot independently accommodate a plurality of independent reactions, or cannot accommodate a substrate containing hydrogel-based microarrays. Most existing apparatus also do not allow introduction of fluids in addition to the sample fluid (such as wash buffers, fluorescent dyes, etc.) into the reaction chamber. Disposable apparatus must be disassembled and reassembled around the biochip every time a new fluid must be introduced. Other existing apparatus are difficult to use in a laboratory environment because they cannot be loaded with standard pipet tips and associated pipettor apparatus.
Many existing apparatus also exhibit unacceptable reaction reproducibility, efficiency, and duration. Reaction reproducibility may be adversely affected by bubble formation in the reaction chamber or by the use of biologically incompatible materials for the reaction chamber. Reaction duration and efficiency may be adversely affected by the presence of concentration gradients in the reaction chamber.
Bubbles can form upon introduction of sample fluid to the reaction chamber or by outgassing of the reaction chamber materials. When gas bubbles extend over the substrate surface in an area containing biologically reactive sites, the intended reaction may intermittently fail or yield erroneous results because the intended concentration of the sample fluid mixture has been compromised by the presence of gas bubbles.
Biologically incompatible reaction chamber materials may cause unacceptable reaction reproducibility, by interacting with the sample fluid, thus causing the intended reaction to intermittently fail or yield erroneous results.
Incomplete mixing of the sample fluid can introduce concentration gradients within the sample fluid that adversely impact reaction efficiency and duration. This effect is most pronounced when there is a depletion of target molecules in the local volume surrounding a biologically reactive site. During a biological reaction, the probability that a particular target molecule will bind to a complementary (immobilized) probe molecule is determined by the given concentration of target molecules present within the sample fluid volume, the diffusion rate of the target molecule through the reaction chamber, and the statistics of interaction between the target molecule and the complementary probe molecule. For diagnostic assays, target DNA molecules are often obtained in minute ( less than picomol) quantities. In practice, it can take tens of hours for a hybridization reaction to be substantially complete at the low target nucleic acid molecule levels available for biological samples. Concentration gradients in the hybridization chamber can further exacerbate this problem.
U.S. Pat. No. 5,948,673 to Cottingham discloses a self-contained multi-chamber reactor for performing both DNA amplification and DNA probe assays in a sealed unit wherein some reactants are provided by coating the walls of the chambers and other reactants are introduced into the chambers prior to starting the reaction in order to eliminate flow into and out of the chamber. No provisions are made for eliminating gas bubbles from the chambers.
There remains a need in the art for methods and apparatus for performing biological reactions on a substrate surface that use a low volume of sample fluid, that accommodate substrates as large as or larger than a conventional microscope slide, that accommodate a plurality of independent reactions, and that accommodate a substrate surface having one or more hydrogel-based microarrays attached thereto. There also remains a need in the art for an apparatus that allows introduction of fluids in addition to sample fluid into each reaction chamber via standard pipet tips and associated pipettor apparatus. There also remains a need in the art for such an apparatus that increases reaction reproducibility, increases reaction efficiency, and reduces reaction duration. There also remains a need in this art for a simple method for removing gas bubbles from such an apparatus. These needs are particularly striking in view of the tremendous interest in biochip technology, the investment and substantial financial rewards generated by research into biochip technology, and the variety of products generated by such research.
The invention provides an apparatus for performing biological reactions on a substrate surface and a method for removing gas bubbles from the apparatus to prevent interference with biological reactions such as hybridization at reaction sites on-the substrate surface. Specifically, the method of the invention is directed to an apparatus comprising a flexible, gas permeable layer affixed to a biochip with an adhesive, wherein the flexible, gas permeable layer, the adhesive, and the biochip enclose a reaction chamber, and a means for facilitating diffusion of gas molecules out of the reaction chamber across the flexible, gas permeable layer. The diffusion-facilitating means creates a pressure gradient or concentration gradient across the flexible, gas permeable layer, thereby increasing the rate of diffusion of gas molecules from the reaction chamber through the flexible, gas permeable layer.
The biochip comprises a substrate having a first surface and a second surface, wherein the first surface contains an array of biologically reactive sites, and is preferably an oligonucleotide array. The array is provided in an area bounded by an adhesive set down on the first substrate surface. The flexible, gas permeable layer, the adhesive and the first substrate surface further define a volume comprising a reaction chamber.
The flexible, gas permeable layer preferably is deformable, translucent, and porous. More preferably, the flexible, gas permeable layer is selectively permeable to gas but impermeable to liquid. Most preferably, the flexible, gas permeable layer is selectively permeable to gases and impermeable to liquids because the surface tension of the sample fluid prevents escape of the liquid through the pores of the flexible membrane.
In certain embodiments of the invention, the substrate comprises a multiplicity of oligonucleotide arrays, which are contained in one or a plurality of areas bounded by the adhesive and covered by the flexible, gas permeable layer.
Each of the reaction chambers also preferably include a first port, and certain embodiments further include a second port, that transverses the substrate and comprises a first opening on the first substrate surface and a second opening on the second substrate surface. The openings of these ports on the second substrate surface are covered by a removable cover, most preferably a foil tape. The openings of these ports on the first substrate surface are provided within the area bounded by the adhesive.
The adhesive, the flexible, gas permeable layer and the substrate also enclose a reaction chamber that is filled prior to use with a water-soluble compound. The water-soluble compound is preferably a solid at a temperature most preferably at or below room temperature, and a liquid at higher temperatures, most preferably below about 100xc2x0 C.
In preferred embodiments, the diffusion-facilitating means creates a pressure differential across the flexible, gas permeable layer. In more preferred embodiments, the diffusion-facilitating means comprises a vacuum source removably affixed to the flexible, gas permeable layer, wherein the vacuum source is used to apply a vacuum to the flexible, gas permeable layer. Most preferably, the vacuum source comprises a vacuum pump connected by a length of plastic tubing to a reducer that completely encloses the area defined by the adhesive and is removably sealed to the flexible, gas permeable layer.
The chamber is also optionally supplied with a roller, most preferably a patterned roller, positioned in contact with the flexible, gas permeable layer and movable longitudinally across the surface of the chamber for mixing sample fluid and wash solutions as required.
Specific preferred embodiments of the present invention will become evident from the following more detailed description of certain preferred embodiments and the claims.

Method and apparatus for performing biological reactions on a substrate surface


This invention relates to lip seals for shafts, whose lip bodies consist of rubber elastic material, and is mounted on the reverse side on an essentially radial surface of a back-up ring which is integral with the housing. When the pressure of the medium to be sealed out increases, dangerous overloads occur on the lip edge, in spite of the roller diaphragm-like deformation of the lip body. According to the invention, these overloads are reduced by the introduction of a trough in the supporting back-up ring in the zone of the lip body near the clamp, into which the lip body is deformed and thus the pressure on the edge of the lip is reduced (FIG. 1 ).

1. Field of the Invention
This invention relates to a lip seal for sealing around a shaft, in particular for sealing a ship's propeller shaft in relation to a fluid medium. Such a seal generally can have a clamping part which can be clamped between a first and second back-up ring integral with the shaft housing, a seal lip for sealing against the shaft, and an intermediate part therebetween. The intermediate part can have two zones, the first zone of which is adjacent to the clamping part and the second zone of which supports the seal lip, whereby the two zones form a folded, elastic joint and are disposed angularly with respect to one another. When the pressure of the medium to be sealed out increases beyond a normal pressure, the angle joint of the intermediate part is deformed toward the shaft and into contact with the second back-up ring.
2. Background Information
Lip seals of this type are disclosed by German Laid Open Patent Appln. Nos. 37 18 411, 37 42 080, 38 17 660 and 39 24 270. In such lip seals, when the pressure of the medium to be sealed out increases, the angle joint is deformed towards the shaft in the manner of a roller diaphragm. Such a deformation results in a reduction of the effective surface area of the second zone of the intermediate part, pressurized by the medium to be sealed out, in the direction of the application force of the seal lip edge. Thus the application force is reduced.
This desirable effect is compromised, or reduced, however, by the fact that the second zone of the intermediate part is shortened, whereby the portion of the contact force caused by the elastic righting moment of the intermediate portion is increased. On account of this force acting in the opposite direction, the above-mentioned depressurization effect is reduced, so that at high pressures of the medium to be sealed out, overheating can occur at the lip edge. Such an overheating can cause leaks or even the complete failure of the seal.
German Laid Open Patent Appln. No. 20 64 542 discloses a lip seal on which a back-up ring integral with the housing has a trough which, at normal pressure of the medium to be sealed out, forms a sickle-shaped gap with the sealing body, and when the pressure of the medium to be sealed out increases, this space is filled by the sealing body. However, the trough of the back-up ring is not located between the fastening point of the sealing body and the angle joint, but between the angle joint and the free, or exposed end of the back-up ring, which backup ring runs approximately parallel to the second zone of the intermediate part. In this configuration, accordingly, the seal lip does not retain its unrestricted ability to follow the oscillations of the shaft.

Lip seal to seal a shaft, in particular a ship's propeller shaft


An electric match having electrical leads embedded in flame-producing compound is protected against an accidental resistance across the leads after firing by a length of heat-shrinkable tubing encircling the match body and having a skirt portion extending beyond the leads. The heat of the burning match and an adjacent thermal battery causes the tubing to fold over the end of the match body, covering the ends of the leads and protecting them from molten pieces of the battery.

The present invention relates generally to electric matches and more particularly to an electric match protected against external resistance after firing by a length of heat-shrinkable tubing.
The electric match or ignitor is a well-known initiator of thermal batteries. These batteries, designed for applications requiring long shelf life, rapid activation and relatively high current for a relatively short operating life, have a heat producing compound such as iron/potassium perchlorate adjacent an electrolyte such as a lithium chloride/potassium chloride eutetic. Examples of thermal batteries are shown in U.S. Pat. No. 3,558,363 of P. J. Franklin and U.S. Pat. No. 3,677,822 of D. M. Bush. The Franklin patent discloses a thermal cell having a single layer each of electrolyte and heat compound, and an electric match positioned in contact with the heat compound. The Bush patent discloses a thermal battery having a stack of alternating layers of electrolyte and heat compound, a combustible fuze strip extending along the stack, and an electric match disposed adjacent an end of the fuze strip. The operation of both batteries is similar in that a burst of flame from the match ignites the heat compound which burns at the proper temperature and rate to melt the electrolyte, thereby activating the battery.
Although many types of matches have been used with thermal batteries, the recent trend has been towards matches of the type shown in U.S. Pat. No. 3,906,858 of J. R. Craig et al. These matches have a solid cylindrical body with a cavity at one end for ignition powder, electrical leads extending through the body to the cavity and a bridgewire across the leads in contact with the ignition powder. In addition to small size and rugged construction, matches of this type permit the selection of ignition powder and bridgewire so that only an intentional large current will ignite the device, while an accidental smaller current will not.
Tests of matches having a body shape similar to the body of the Craig patent and using titanium/potassium perchlorate powder show these matches can withstand a current of one amp, 1 watt for 5 minutes without firing, yet fire within three milliseconds upon application of the designed firing current of three and one half amps. The flame produced by the matches has been observed on film to extend over thirty inches from the match, with the ignition producing sufficient force to blow away the sealing cover placed over the end of the match.
The ignition powder of an electric match burns without leaving a significant residue and the resistive wire is consumed by the heat of the electric current and the match. Accordingly, after ignition the match consists of only the body and the electrical leads.
However, the thermal battery creates a significant residue, consisting principally of molten electrolyte. It has been found that a piece of this residue occasionally comes into contact with the exposed lead ends of the fired match, causing an electrical short on the match ignition circuit. This unexpected short circuit may adversely effect the performance of the equipment which energized the battery.

Resistance after firing protected electric match

The United States of America as represented by the United States Department of Energy


A flash phase analysis circuit provides parallel phase channels for simultaneously analyzing a detected signal in each of several phase windows and providing parallel outputs indicating whether a target falls in one of the phase windows. In one implementation, the parallel outputs each drive a segment of an output device to indicate the target type to the user. The flash phase analysis circuit divides a detected signal among the phase windows and then simultaneously compares the measured signal at each phase window with a reference signal. The circuit matches measured data with pre-selected phase characteristics corresponding to known targets in parallel and provides parallel output signals indicating target type.

Metal detectors typically identify the type of a metal object located in a background environment by analyzing the characteristics of an electrical signal attributable to the target. In particular, some metal detectors identify target type by analyzing the phase relationship between a signal transmitted into the ground and a received signal. For example, some metal detectors use phase detectors, sometimes called "synchronous detectors," to measure the received signal at two different phases, usually 90.degree. apart. When the phase detectors are 90.degree. apart, they are referred to as being in "quadrature." The output of each of the phase detectors is a D.C. signal proportional to the magnitude of the received signal at a selected phase angle. The ratio between these D.C. signals is proportional to the phase relationship between transmitted and received signals.
Conventional metal detectors analyze the measured ratio by sequentially comparing it to a series of expected ratios. Such detectors compare the measured ratio with a series of expected ratios one by one until they find the best match. Typical digital and microprocessor based systems, for example, sequentially analyze measured phase data by stepping through a pre-defined series of ranges to find a best fit. Often, this approach is expensive to implement, causes switching noise and signal delays, and can be less accurate.

Metal detector target identification using flash phase analysis


The disclosure of the present specification provides a method for receiving a downlink control channel, which is repeated on a plurality of downlink subframes, by a wireless device in a wireless communication system. The method may comprise the steps of: attempting, by the wireless device, blind decoding of the downlink control channel, using one or more of multiple scrambling codes; when the blind decoding is successful, determining, by the wireless device, a repetition level for the downlink control channel on the basis of a scrambling code by which the wireless device has been successful in the blind decoding; and determining, by the wireless device, the number of repetitions of the downlink control channel according to the repetition level.

Field of the Invention
The present invention relates to mobile communication.
Related Art
3rd generation partnership project (3GPP) long term evolution (LTE) evolved from a universal mobile telecommunications system (UMTS) is introduced as the 3GPP release 8. The 3GPP LTE uses orthogonal frequency division multiple access (OFDMA) in a downlink, and uses single carrier-frequency division multiple access (SC-FDMA) in an uplink. The 3GPP LTE employs multiple input multiple output (MIMO) having up to four antennas. In recent years, there is an ongoing discussion on 3GPP LTE-advanced (LTE-A) evolved from the 3GPP LTE.
As disclosed in 3GPP TS 36.211 V10.4.0 (2011-12) "Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation (Release 10)", a physical channel of LTE may be classified into a downlink channel, i.e., a PDSCH (Physical Downlink Shared Channel) and a PDCCH (Physical Downlink Control Channel), and an uplink channel, i.e., a PUSCH (Physical Uplink Shared Channel) and a PUCCH (Physical Uplink Control Channel).
Meanwhile, in recent years, research into communication between devices or the device and a server without human interaction, that is, without human intervention, that is, machine-type communication (MTC) has been actively conducted. The MTC represents a concept in which not a terminal used by human but a machine performs communication by using the existing wireless communication network.
Since MTC has features different from communication of a normal UE, a service optimized to MTC may differ from a service optimized to human-to-human communication. In comparison with a current mobile network communication service, MTC can be characterized as a different market scenario, data communication, less costs and efforts, a potentially great number of MTC devices, wide service areas, low traffic for each MTC device, etc.
Meanwhile, recently, extension or enhancement of cell coverage of a base station (BS) for MTC devices has been considered. However, when an MTC device is placed in a coverage extension (CE) or a coverage enhancement (CE) area, a downlink channel may not be properly received. To this end, the BS may consider to repeatedly transmit the same downlink channels on a plurality of subframes.
However, if the MTC device cannot identify the number of repetitions of downlink control channel repeated on a plurality of subframes, the MTC device cannot properly receive a downlink data channel, or the like.

Method and wireless device for receiving downlink control channel


A vehicle height adjustment device includes front forks, a rear suspension, a weight estimation unit, and a front wheel-side target movement amount determination unit. The front fork includes a front wheel-side suspension spring and a front wheel-side support member, which supports one end of the front wheel-side suspension spring, and moves toward another end of the front wheel-side spring to change the front wheel-side suspension spring length. The rear suspension includes a rear wheel-side suspension spring and a rear wheel-side support member, which supports one end of the rear wheel-side suspension spring, and moves toward another one end of the rear wheel-side spring to change the rear wheel-side suspension spring length. The weight estimation unit estimates a weight applied to a vehicle. The front wheel-side target movement amount determination unit decreases, a movement amount of the front wheel-side support member as the estimated weight increases.

Japanese Examined Patent Publication No. 8-22680 discloses a vehicle height adjustment device that increases the height of a motorcycle during travel and that decreases the height of the motorcycle during halt in order to facilitate a rider's or a passenger's getting on and off the motorcycle.
The vehicle height adjustment device automatically changes the height of the motorcycle in response to its speed of travel. Specifically, the vehicle height adjustment device automatically increases the vehicle height when the vehicle speed reaches a set speed, and automatically decreases the vehicle height when the vehicle speed becomes equal to or lower than a set speed.


An open-end or box wrench with a ratcheting socket wrench at the opposite end of the wrench handle. The ratcheting socket wrench may be either fixedly or pivotally attached. In one embodiment of the invention, a socket is permanently affixed to the ratchet mechanism. In another embodiment of the invention, a drive member for releasable attachment to sockets is permanently affixed to the ratchet mechanism. In either embodiment, the ratchet mechanism is preferably reversible.

Wrenches are available in a wide variety of styles and sizes. The most common types of wrenches are likely the open-end wrench and the box wrench. The open-end wrench has an opening of particular size and two parallel sides for engaging opposite sides of a fastener. The box wrench generally has a polygonal opening for contacting the circumferential surfaces of a fastener. Both of these wrenches are widely known in the art.
There also exist ratcheting socket wrenches, which hasten the process of inserting or removing a fastener considerably since ratcheting socket wrenches do not require that the wrench be removed from the fastener at the end of each turn. Ratcheting socket wrenches also have the advantage of being employable for a variety of fasteners, as sockets of diverse size may be releasably attached to the ratcheting body.
The disadvantage of most ratcheting socket wrenches is their size. Many times the ratchet and socket mechanism simply will not fit into the work envelope. Another common problem is that many times the insertion or removal of a fastener may be initiated with a ratcheting socket wrench, yet an open-end or box wrench is often required to finish the process. Such a situation may occur when, for example, space limitations around a fastener increase as the fastener's head position changes during insertion or removal. In this situation it is common to have and employ, both a ratcheting socket wrench and an open-end or box wrench. This entails the purchase of a wrench and a socket for each fastener size. Storage space becomes an issue, and there is the added annoyance of assuring that both wrench types are accessible when needed.
One aspect of the present invention is the elimination of the need for separate sockets and wrenches for the same fastener size. Another aspect of the present invention is a device that conveniently combines the benefits of both types of wrenches on one handle, thereby eliminating the need to search for and have available a second wrench.
The present invention contemplates a wrench having an open-end or box wrench at one end and a ratcheting socket wrench at the opposite end. The ratcheting socket wrench portion is made to pivot about the wrench handle to provide maximum flexibility of use.
In one embodiment of the present invention, the ratcheting socket wrench has a socket which is permanently affixed to the ratcheting body and fits the same size fastener as the open-end or box wrench on the opposite side of the wrench handle. In the preferred embodiment of the invention, the ratcheting direction of the ratcheting socket wrench may be reversed by pulling axially downward on the socket and turning the socket slightly left or right as required.
In another embodiment of the present invention, a coupling member replaces the socket member. The coupling member is designed for releasable attachment to common sockets, thus allowing the ratcheting socket wrench to be used on fasteners of various size. The ratcheting mechanism may be designed for use with a particular range of socket sizes based on the size of the open-end or box wrench portion. This would eliminate the need for installing on every wrench, a ratcheting mechanism capable of withstanding the load of an entire socket size range. In this embodiment of the invention, the ratcheting direction of the ratcheting socket wrench may also be reversed by pulling axially downward on the socket and turning the socket slightly left or right as required.


A compact diffuser for high-power gas turbines, comprising a first diffusion section of substantially axial path defined by two conical coaxial walls, followed by a double curved diffuser with three walls, of which the intermediate wall is cantilever-supported by a set of aerodynamically profiled ribs disposed horizontally and situated near the exit of said double curved diffuser. The diffuser is connected to the turbine exhaust casing by an envelope internal to said exhaust casing and having its contours smoothly joined to the diffuser.

The diffusers most frequently used in power gas turbines are known to be derived from those designed and arranged for aeronautical turbines in which a small overall radial dimension is essential, and in which the diffusion duct must be traversed by aerodynamically profiled double-wall ribs, which are cooled in the interspace with cold gas for supporting the shaft bearing which would otherwise not be reachable.
These diffusers are compromised of two coaxial conical walls with an angle of about 7.degree. between the cones. In this respect, a diffuser of this type has its maximum efficiency under conditions of best compromise between the friction loss at the two walls, which is dependent on length for equal surface finishes and is thus smaller the shorter the diffuser, and the diffusion turbulence losses which are smaller the more gradual the diffusion and thus the longer the diffuser. It has been found experimentally that the optimum compromise length, dependent on degree of finish, velocity etc., corresponds as a first approximation to an angle between the cones of about 7.degree. for two-wall diffusers of prevalently axial extension.
On the other hand, the gas is still at high velocity when leaving the diffuser, and its energy is therefore lost, but as the exhaust is axial and taking into account the aeronautical compromise between weight, overall size and efficiency, this loss is accepted.
Land-based turbines, which derive from aeronautical experience, use similar diffusers, the only difference being that at the end of the diffuser the gas is made to curve into the radial direction due to the fact that the exhaust is radial in land-based turbines. In order to curve the gas with smaller losses and smaller radii, formations of deflectors are often arranged in the bend, and have a cross-section in the form of parallel circular arcs. Gas diffusion is considered finished at the end of the conical portion, and the deflectors serve only to reduce the pressure drop through the bend, and not for diffusion purposes.
Land-based turbines derived from aeronautical technology do not exploit the larger range of alternatives offered by land installations over aeronautical installations for the following reasons:
a) they retain the bearing support ribs at the diffuser inlet where the gas is of considerable velocity, resulting in a certain loss which becomes much greater if the turbine has to operate under other than design conditions. In such a case the loss caused by the reduction in cross-section during passage through the ribs is supplemented by the loss caused by the impact of the gas against the ribs, this impact occurring at an angle of incidence which is more removed from the optimum angle the more the operation deviates from the design point (in the case of land-based turbines, it is not unusual to have to operate at 50% of the initial design speed). In the aeronautical turbine, the ribs are essential for overall size and weight reasons. In the land-based turbines, the bearing could instead be supported from the outside if certain mechanical problems related to the shaft line are solved; and
b) they do not reduce the exhaust gas velocity to a minimum without negative effects in the efficiency and noise level.
One type of diffuser which is beginning to be adopted in land-based turbines is precisely characterized by the elimination of these ribs and an attempt to improve diffusion in the final bend. The ribs are eliminated by supporting the bearing from the outside, given that the exhaust is no longer axial, and the bend is made in the form of a truly curved diffuser which is much more complicated than a straight diffuser but which by careful design and experimental setting-up can attain a further worthwhile recovery.
In order to further improve this type of diffuser, it is necessary either to increase the axial conical portion so as to arrive at the bend with a greater diffusion ratio, which however causes an intolerable increase in the axial turbine length, or to dispose an intermediate wall in said portion so as to double the diffusion angle. This path has been followed in particular by those manufacturers who retain the bearing support ribs so as to also support the intermediate wall by these latter. However, this design gives only insignificant results for obvious reasons. In this respect, by retaining the ribs, all the aforesaid losses under working conditions other than the design condition still occur, and in addition because of the said balance between friction losses and diffusion losses, the introduction of the double wall into the zone in which the gas is still at high speed leads to an increase in losses due to friction and entry impact, which strongly reduce the theoretical advantages of the increased diffusion.
A second path would be to increase the curved diffuser portion, but this would lead to an increased overall radial dimension which in the case of large turbines is even less desirable (transport problems etc.).

Compact diffuser, particularly suitable for high-power gas turbines


A method is provided for allocating resources by a Base Station (BS) in a wireless communication system. The method includes persistently allocating one or more resource slots among a plurality of resource slots, the persistently allocated one or more resource slots being allocated to corresponding one or more Mobile Stations (MSs), de-allocating at least one persistently allocated resource slot of the one or more persistently allocated resource slots, determining whether a hole is created due to the de-allocation among the one or more persistently allocated resource slots not de-allocated, and shifting a location of at least one of the one or more non-de-allocated persistently allocated resource slots when it is determined that the hole is created due to the de-allocation.

1. Field of the Invention The present invention relates to a method and apparatus for allocating resources in a wireless communication system and a system thereof. More particularly, the present invention relates to a method and apparatus for allocating resources in a wireless communication system using a persistent resource allocation scheme and a system thereof.
2. Description of the Related Art
Next-generation communication systems are being developed to provide various high-speed, high-capacity services to Mobile Stations (MSs). A next-generation communication system includes an Institute of Electrical and Electronics Engineers (IEEE) 802.16 communication system and a Mobile Worldwide Interoperability for Microwave Access (WiMAX) communication system. The Mobile WiMAX communication system is a communication system based on the IEEE 802.16 communication system.
With reference to FIG. 1, a description will now be made of a frame structure in an IEEE 802.16 communication system.
FIG. 1 is a diagram illustrating a frame structure in an IEEE 802.16 communication system.
As illustrated in FIG. 1, a frame 111 includes a DownLink (DL) subframe 113, a Transmit/Receive Transition Gap (TTG) interval 115, an UpLink (UL) subframe 117, and a Receive/Transmit Transition Gap (RTG) interval 119. A length of the frame 111 is tframe, a length of the DL subframe 113 is tDL—subframe, a length of the TTG interval 115 is tTTG, a length of the UL subframe 117 is tUL—subframe, and a length of the RTG interval 119 is tRTG.
The DL subframe 113 includes a preamble region 121, a Frame Control Header (FCH) region 123, a DL_MAP region 125, a UL_MAP region 127, and a DL data burst region 129. A synchronization signal, e.g., preamble signal, for synchronization acquisition between a signal transmission apparatus, e.g., a Base Station (BS), and a signal reception apparatus, e.g., a MS, is transmitted during the preamble region 121. Basic information on subchannels, ranging and a modulation scheme is transmitted during the FCH region 123. A DL_MAP message is transmitted during the DL_MAP region 125, and a UL_MAP message is transmitted during the UL_MAP region 127. The DL_MAP message includes a DL_MAP Information Element (IE) indicating information about the DL data burst region 129. The UL_MAP message includes a UL_MAP IE indicating information about a UL data burst region 133. DL data bursts are transmitted during the DL data burst region 129.
The UL subframe 117 includes a control region 131 and the UL data burst region 133. Although not separately illustrated in FIG. 1, the control region 131 includes a ranging region, a Channel Quality Indicator Channel (CQICH) region, an ACKnowledgment (ACK) channel (ACKCH) region, and a sounding region. The ranging region is a region during which an MS transmits a ranging code, and when performing an initial network entry operation, performing a handoff operation or requesting resource allocation, an MS transmits a ranging code through the ranging region according to its purpose. The CQICH region indicates a region during which an MS transmits its CQI, and the ACKCH region indicates a region during which an MS transmits its success/failure in reception of DL data bursts. A sounding signal for allowing an MS to perform UL channel estimation is transmitted during the sounding region.
As described in FIG. 1, the IEEE 802.16 communication system allocates resources to an MS to exchange DL and UL traffic data with it, and provides the resource allocation information to the MS using a resource allocation message. The resource allocation message can be a DL_MAP message or a UL_MAP message. A transmission period of the DL_MAP message and UL_MAP message is a frame period.
However, in the service where traffic data is periodically transmitted to an MS, for example, in Voice over Internet Protocol (VoIP) service, BSs transmitting a resource allocation message at every frame to transmit resource allocation information for the resources allocated to the corresponding MS may cause an unnecessary waste in resources. Therefore, when providing a service having a periodic traffic transmission period like the VoIP service, it is preferable to persistently allocate resources for the corresponding MS. A scheme of persistently allocating resources for a particular MS is referred to as a 'persistent resource allocation scheme'. For convenience, the persistent resource allocation scheme will be referred to herein as a 'circuit-mode resource allocation scheme'.
When using the circuit-mode resource allocation scheme, an MS, once it is allocated resources from a BS, can persistently use the allocated resources without receiving the resource allocation message at every frame. Of course, when the resource allocation for the MS is changed or released, the BS can notify the MS of the change and release of the resource allocation using a separate resource allocation message. As a result, when using the circuit-mode resource allocation scheme, the BS has no need to transmit the resource allocation message at every frame, thereby making it possible to prevent the waste of resources caused by the transmission of the resource allocation message.
With reference to FIG. 2, a description will now be made of a resource allocation method based on a circuit-mode resource allocation scheme in an IEEE 802.16 communication system.
FIG. 2 is a diagram schematically illustrating a resource allocation method based on a circuit-mode resource allocation scheme in an IEEE 802.16 communication system.
Before a description of FIG. 2 is given, it should be noted that the IEEE communication system uses two resource allocation schemes, namely a packet-mode resource allocation scheme and a circuit-mode resource allocation scheme. Referring to FIG. 2, both a resource allocation method based on the packet-mode resource allocation scheme and a resource allocation method based on the circuit-mode resource allocation scheme are illustrated. For convenience, however, a description of the resource allocation method based on the packet-mode resource allocation scheme will be omitted herein. For convenience, resources allocated using the circuit-mode resource allocation scheme will be referred to as 'circuit-mode resources'.
The slot numbers referred to herein and illustrated in FIGS. 2 and 3 are numbered separately for each of the packet-mode resource allocation scheme and the circuit-mode resource allocation scheme in order to simplify the explanation. The slot numbers for the packet-mode resource allocation scheme are numbered in the same direction as the resource allocation beginning with the first slot used for the packet-mode resource allocation scheme. The slot numbers for the circuit-mode resource allocation scheme are numbered in the opposite direction to the resource allocation beginning with the last slot used for the packet-mode resource allocation scheme. The slot numbers used herein are merely for the purpose of explanation and any other slot numbering scheme may equally be used, such as numbering all of the slots of a subframe. Further, the direction of the resource allocation is merely an example, as at least one of the packet-mode resource allocation scheme and circuit-mode resource allocation scheme may employ a resource allocation in a direction opposite to that described herein.
Referring to FIG. 2, when resources are allocated for UL data bursts included in a UL subframe using the circuit-mode resource allocation scheme, UL resources are allocated slot by slot beginning from a start offset. The start offset indicates a location from which the BS starts allocating UL resources using the circuit-mode resource allocation scheme, and a slot #10 assumed to be the start offset in FIG. 2. A detailed description of the start offset will be given below.
For example, in FIG. 2, a circuit-mode resource #1 includes 2 slots in the forward direction from slot #10, which in this example is the start offset, a circuit-mode resource #2 includes 2 slots in the forward direction from a slot #8, which is the next slot of the slots included in the circuit-mode resource #1, and a circuit-mode resource #3 includes 6 slots in the forward direction from a slot #6, which is the next slot of the slots included in the circuit-mode resource #2.
However, the use of the circuit-mode resource allocation scheme described in FIG. 2 may cause a reduction in resource efficiency, which will be described with reference to FIG. 3.
FIG. 3 is a diagram illustrating a case where a circuit-mode resource is de-allocated in an IEEE 802.16 communication system.
Referring to FIG. 3, it is assumed that the circuit-mode resource #2 among the 3 circuit-mode resources allocated in FIG. 2 is de-allocated. It is also assumed that after the circuit-mode resource #2 is de-allocated, a circuit-mode resource #4, or a new circuit-mode resource, may be allocated. The number of slots included in the circuit-mode resource #4 is assumed to be 4. In this case, the number of slots included in the circuit-mode resource #4 exceeds the number 2 of slots included in the de-allocated circuit-mode resource #2. Therefore, the circuit-mode resource #4 cannot use the slots which were included in the circuit-mode resource #2, and should therefore include new slots following the circuit-mode resource #3 that as illustrated in FIG. 3 would comprise larger slot numbers than the start offset. The slots included in the circuit-mode resource #4 include 4 slots in the forward direction from a slot #14, which is the new start offset. As a result, the 2 slots of a slot #8 and a slot #7, which were included in the de-allocated circuit-mode resource #2, become a hole, and the hole is an unavailable resource.
As described in FIG. 3, the use of the circuit-mode resource allocation scheme may cause creation of the hole, impeding continuity of resource allocation. The creation of the hole reduces the resource efficiency, resulting in a decrease in efficiency of the IEEE 802.16 communication system.

Method and apparatus for allocating resources in a wireless communication system and system thereof