A liquid ejection apparatus including an ejection head having a nozzle in which liquid is ejected through the nozzle, a plurality of cartridges that retain the liquid and supplies the liquid to the ejection head, and a switching mechanism that switches liquid to be supplied to the ejection head from a plurality of types of liquid supplied from the cartridges. The switching mechanism includes a body having a communication passage in communication with the ejection head, a first diaphragm chamber and a second diaphragm chamber that communicate with each other through the communication passage and located to facing each other, a first diaphragm and a second diaphragm arranged in the first diaphragm chamber and the second diaphragm chamber, respectively, and capable of opening and closing the communication passage, and an operation mechanism provided in the communication passage. The operation mechanism includes a first operation end and a second operation end that operate the first diaphragm and the second diaphragm, respectively, when the communication passage is opened to allow communication between at least one of the first and second diaphragm chambers and the ejection head, and an urging member that urges the first and second operation ends in a direction in which the communication passage is opened by the first and second diaphragms.

1. Technical Field
The present invention relates mainly to a liquid ejection apparatus used as an inkjet type recording apparatus that forms dots on a recording medium by ejecting ink droplets from nozzles in accordance with printing data and a method of initial filling of the liquid ejection apparatus.
2. Related Art
As a liquid ejection apparatus that ejects liquid onto a target, an inkjet type recording apparatus that performs printing by ejecting ink onto a recording paper sheet is known. This type of apparatus suppresses noise generated through printing to a relatively low level and is capable of forming small-sized dots at a high density. Therefore, an inkjet type recording apparatus is now frequently used for printing including color printing. Such apparatus includes an inkjet type printing head and a paper feeder mechanism. Ink is supplied from an ink cartridge to the printing head. The paper feeder mechanism transports a recording medium in a direction perpendicular to the scanning direction of the printing head.
The inkjet type recording apparatus performs recording by ejecting ink droplets onto the recording medium through mechanical pressure or thermal energy applied to the printing head while moving the printing head mounted in a carriage along the width of the recording medium (in the main scanning direction). Specifically, a printing head that ejects, for example, black ink and different color inks such as yellow, cyan, and magenta inks is mounted in the carriage of the inkjet type recording apparatus. The recording apparatus performs not only text printing using the black ink but also full-color printing by changing the ejecting proportion of the inks.
Further, to improve the quality of the color printing, a recording apparatus employing ink of a total of six colors, including black, has been developed. The six colors include light cyan, and light magenta as well as the aforementioned colors. Also, there is a demand for an inkjet type recording apparatus capable of performing large-scale printing on large-sized sheets of paper without replacing ink cartridges. In these cases, ink cartridges with increased capacities become necessary for supplying ink to the recording heads. To satisfy the demand, a recording apparatus configured as will be described in the following has been developed. Specifically, for example, ink cartridges are removably mounted not in a carriage but in cartridge holders arranged in securing portions formed at opposite side portions of the body of the apparatus. Ink is supplied from each of the cartridge holders to a printing head through, for example, a flexible tube and an ink supply passage.
This inkjet type recording apparatus can be applied to various types of printing through ejection of ink droplets from nozzle openings of the printing head. The ink cartridges are replaceable in accordance with the purposes for printing. In other words, if printing needs to be carried out with inks of different types than the inks retained in the currently mounted ink cartridges, the ink cartridges are temporarily separated from the apparatus and replaced by ink cartridges retaining desired types of ink. This structure leads to frequent demands for printings of different printing qualities using different types of inks in the same printer.
However, replacement of the ink cartridges is troublesome for the user of the recording apparatus. If an increased number of cartridges needs to be replaced, such troublesome user operation must be repeated a number of times. In a printing apparatus described in JP-A-2003-237100, the types of ink ejected from corresponding nozzle rows can be changed without replacing ink cartridges. Nonetheless, the apparatus does not allow such switching of the ink types in correspondence with the nozzle rows and is not applicable to a case in which the ink types must be switched in correspondence with the nozzle rows.
JP-A-2001-219574 describes a switch structure that allows switching of ink cartridges in correspondence with nozzle rows. However, the switch structure switches the ink cartridges, which are connected to the nozzle rows. Specifically, the number of ink cartridges that are simultaneously connected to each of the nozzle rows is always one. This makes it necessary to perform initial ink filling for each of the ink cartridges before the ink cartridges are initially used, which is disadvantageous. Further, in the recording apparatus having the above-described switch structure, there may be a case in which only one of the cartridges is used. In this case, bubbles may be generated in a corresponding ink passage, leading to a defect in ink ejection.

Liquid ejection apparatus and initial filling method of the same


Broadly, the present invention relates to furan no-bake foundry binders where bisphenol A tar (BPAT) is used to replace a portion of the furfuryl alcohol and any conventional filler optionally included in for binder formulation. Reduction in the amount of furfuryl alcohol in the foundry binder formulation may lead to a reduction in the cost and an improvement in early strength of these formulations. Accordingly, in a furan no-bake foundry binder of a resin derived from a major proportion of furfuryl alcohol and optionally fillers, the improvement which comprises at least a fraction of said furfuryl alcohol being bisphenol A tar. Bisphenol A tar also can replace at least a fraction of any filler included in the binder formulation.

The present invention relates to the manufacture of no-bake foundry binders and more particularly to a furan no-bake foundry binder containing bisphenol A tar (BPAT) filler. A "no-bake foundry binder", as used herein, means an organic chemical solution that is mixed into foundry sand and cured at ambient temperature by the action of an acid catalyst. The cured sand forms are used in metal casting operations.
Furfuryl alcohol is the key ingredient in furan no-bake foundry sand mold and core formulations. Furfuryl alcohol often is in short supply and is high in cost. Inexpensive fillers are used to reduce the cost of these formulations by replacing at least a fraction of the furfuryl alcohol. Such fillers must be compatible with the ingredients in the formulation. Most such fillers are by-products resulting from various industrial processes. Examples of such traditional fillers include residues from the ozone oxidation production of azeleic acid; by-products (mixed esters) from the production of terephthalic acid and its esters; lignins and lignosulfonates from the paper industry; and various rosins from the forest industry.
Heretofore, for example, bisphenol A tar has been proposed for use in phenolic-based, heat-cured foundry shell resin formulations (British Pat. No. 2,271,357).

Use of bisphenol a tar in furan no-bake foundry binders


According to the present invention there is provided a process for producing an acid anhydride by reacting a carboxylic acid, preferably a carboxylic acid having a polymerizable group, with a sulfonyl halide compound in the presence of a tertiary amine or in the presence of a tertiary amine and an inorganic base, wherein the tertiary amine or the tertiary amine and the inorganic base are used in an amount of 0.9 to 1.2 equivalents relative to the acid generated from the sulfonyl halide compound.

As the process for producing an acid anhydride, there has been a process which comprises reacting a low-molecular acid anhydride such as acetic anhydride with a high-molecular carboxylic acid [for example, J. Am. Chem. Soc. 63 699 (1941)], or a process which comprises reacting a low-molecular acid anhydride with a high-molecular carboxylic acid chloride to form a high-molecular acid anhydride (for example, JP-A-5-339194). In these processes, the low-molecular carboxylic acid formed as a by-product or a carboxylic acid chloride is removed by azeotropic distillation with a solvent. With these processes, however, it is difficult to produce a low-molecular acid anhydride and the yield thereof is low. Further, this process has a problem in that it is unapplicable to production of an acid anhydride which is thermally unstable.
As the process for producing a low-molecular acid anhydride, there is known a process which comprises reacting an acid halide with a carboxylic acid and wherein the inorganic acid formed as a by-product is removed (for example, JP-A-9-104642) or a process which comprises reacting an acid halide with a metal carboxylate and wherein the metal salt formed is removed [for example, J. Org. Chem. 60(7) 2271 (1995)]. Even with these processes, however, the yield of the acid anhydride obtained is not satisfactory. Further, the reaction using an acid halide is inferior in the safety of reaction.
Meanwhile, as the process for producing a low-molecular acid anhydride at a good yield, there is known a process which comprises reacting a carboxylic acid with methanesulfonyl chloride in the presence of triethylamine [J. Chem. Res., Synop. 3 100 (1984)]. In this process, 2 equivalents of a carboxylic acid is reacted using 2.1 equivalents of methanesulfonyl chloride [therefore, the acids (hydrochloric acid and methanesulfonic acid) formed by the reaction with methanesulfonyl chloride become 2.1 equivalents] and 3.33 equivalents of triethylamine (this trimethylamine amount becomes 1.67 equivalents relative to the acids formed from methanesulfonyl chloride). In this reaction, triethylamine is used in an amount fairly larger than the stoichiometric amount required for the raw material carboxylic acid and methanesulfonyl chloride in order to accelerate the reaction. This reaction is conducted at −15° C. using tetrahydrofuran as a solvent.
After the reaction, tetrahydrofuran is distilled off under reduced pressure; ethyl acetate is added to the residue for dissolution; and the ethyl acetate phase is washed with an aqueous sodium hydrogencarbonate solution. Thereafter, the ethyl acetate phase is dried over anhydrous sodium sulfate, after which the solvent therein is distilled off to obtain an intended acid anhydride.
The above reaction is highly reactive and tends to give rise to a side reaction. As a result, the yield tends to be inferior and the reaction has a room for improvement. Particularly when the carboxylic acid is a polymerizable group-containing carboxylic acid such as acrylic acid or methacrylic acid [hereinafter the both are referred to as (meth)acrylic acid], a fairly large proportion of the acid anhydrides obtained is a polymer(s), which greatly reduces the yield of an intended product.
Further in the above process using a large amount of triethylamine, washing with water is conducted after the reaction in order to remove triethylamine from the product; however, the compound has a strong odor and is unable to remove sufficiently.
Furthermore, a triethylamine salt is contained in a large amount in the waste solution generated from the above washing with water, which poses a problem of waste solution disposal.
Thus, it is desired to develop a process for producing an acid anhydride, which can produce an acid anhydride at a high yield and a high purity, wherein the purification of intended product from reaction mixture is easy, and wherein the waste solution disposal is easy as well.

Process for production of acid anhydride


A pressure balance valve contains: a receiving chamber including an external cold-water inlet, an external hot-water inlet, an external cold-water outlet, and an external hot-water outlet; a valve core including a pressure sensing fence, a first ring portion and a second ring portion. Between the first ring portion and the pressure sensing fence is defined a cold-water pressure cavity, and between the second ring portion and the pressure sensing fence is defined a hot-water pressure cavity. The first ring portion has an internal cold-water inlet and an internal cold-water outlet, the second ring portion has an internal hot-water inlet and an internal hot-water outlet. The first ring portion also has at least one first fixing slot for fitting with at least one first resilient loop, and the second ring portion also has at least one second fixing slot for fitting with at least second resilient loop.

A conventional pressure valve is applied in various water supply devices, such as conventional or digital showering systems, as disclosed in U.S. Pat. No. 8,267,111 B2, US Publication Nos. US 2013/0042923 A1 and US 2012/0138177.
The water supply device is normally a temperature control faucet and includes a thermostatic valve and a temperature sensing element for matching with the thermostatic valve; the thermostatic valve can adjust desired mixing ratio of cold water and hot water based on a preset showing temperature.
The thermostatic valve can adjust the desired mixing ratio of the cold water and the hot water by adjusting a size of each of a cold-water orifice and a hot-water orifice. However, when the cold-water pressure of the cold-water orifice and the hot-water pressure of the hot-water orifice are not equal, the desired mixing ratio of the cold water and the hot water cannot be adjusted precisely. To overcome such a problem, a pressure balance valve is fixed on an inlet end of the water supply device so as to automatically adjust water pressures of the cold water and the hot water, thus balancing the cold-water pressure of the cold-water orifice and the hot-water pressure of the hot-water orifice.
Conventional pressure balance contains a housing, a fitting sleeve disposed in the housing, and a valve core, wherein between the housing and the fitting sleeve is defined a receiving chamber so that the valve core axially slides in the receiving chamber. The valve core includes a cold-water pressure room and a hot-water pressure room which are spaced from each other by a pressure sensing fence, and the pressure sensing fence has a cold-water detection face and a hot-water detection face so that the cold-water pressure in the cold-water pressure room and the hot-water pressure in the hot-water pressure room act on the cold-water detection face and the hot-water detection face, when a pressure difference between the cold-water pressure and the hot-water pressure is sensed, the valve core acts on the pressure sensing fence and automatically slides so as to balance the cold-water pressure and the hot-water pressure.
A receiving chamber of a pressure balance valve of another temperature control faucet is defined by a part of components of a thermostatic valve, such as, a thermostatic valve core in a cylinder shape, an end plug mounted on one first end of the thermostatic valve core, and a central shaft fixed on a second end of the thermostatic valve core. The central shaft drives the thermostatic valve core rotates in a valve seat of the thermostatic valve so as to adjust a mixing ratio of cold water and hot water, such that a peripheral fence of the receiving chamber can be rotated as well during mixing the cold water and the hot water together.
Accordingly, the valve core of the pressure balance valve has to axially slide quickly and accurately according to the pressure difference of the cold-water pressure and the hot-water pressure, hence a high stability and precision of the pressure balance valve is required.
Likewise, in some conditions, the valve core has to stop the cold water flowing into the cold-water pressure room or to stop the hot water flowing into the hot-water pressure room, a high tightness between the valve core and the housing is therefore required as well. To comply with above-mentioned requirements, a gap between an outer surface of the valve core and an inner surface of the housing has to be less than 0.03 mm, and the outer surface of the valve core and the inner surface of the housing have to be machined smoothly, thus causing high machining cost.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.


The method of supporting and transporting hot flat glass on a gas bed for ceramicizing includes arranging a number of spaced-apart porous or perforated planar segments to form a base with a gas-permeable support surface so that slits, which are narrower than the planar segments, are formed between them, forcing gas through the porous or perforated planar segments and conducting the gas away through the slits between them so as to form the gas bed with no static pressure zones and with a parabolic pressure distribution and producing a predetermined temperature profile for ceramicizing through which the hot flat glass is transported on the gas bed without deformation and without any contact between it and the base. The resulting glass ceramic has smoother surfaces without pits or deformations.

1. The Field of the Invention
The invention relates to a method for supporting and transporting hot flat glass on a gas bed, which is built up over a gas-permeable support surface of a base, in a contactless manner by passing a gas through the support surface.
The invention also relates to a device for performing this method.
2. Related Art
In the conventional glass ceramicizing process typically used in the industry, the glass to be ceramicized, typically in the form of a plate-shaped or fiat green glass body, rests on a solid base. Since during the ceramicization process temperatures and viscosities are reached at which the glass surface can be harmed by mechanical contact with the base, spot-shaped impressions due to adhesion known as "pits" appear on the underside of the glass. Due to shrinkage occurring during ceramicization, relative motion between the supported glass and the base also occurs, creating scratches on the glass surface.
These disadvantages, which result from contact of the green glass plate with the solid base, seemingly suggest employing principles from float glass production. However, the ceramicization process differs from the usual float glass tempering process in that substantially higher temperatures are required, usually up to about 950° C., but in special cases even up to 1250° C., instead of about 500° C. to 700° C. in the case of tempering and bending furnaces for float glass. In addition, temperature homogeneity in the range of a few degrees K must be guaranteed to prevent deformations of the glass ceramic.
It is known to ceramicize glass in contactless fashion by retaining the green glass molded body to be ceramicized on a gas bed in which the supporting gas, as a rule air, flows out of a permeable base and builds up a load-bearing air bed between this base and the green glass molded body. Since there is no direct contact between a solid base and the green glass body, the aforementioned disadvantages cannot arise.
British Patent 1,383,202 discloses a corresponding device for contactless ceramicizing of a green glass plate on an air bed. However this known device has various disadvantages, because air is only supplied through perforated plates but is not drawn off through the base. With typical perforations in the plates, a comparatively high permeability is achieved.
Calculations show that in the middle region of the green glass plate to be ceramicized the gas speed is nearly zero and a "static" pressure is generated. Then a gas flow from the gas bed occurs essentially only in the vicinity of the edge of the plate. In contrast to the pressure in the edge region, the static pressure in the middle of the plate does not change in response to changes in the thickness of the gas film. Accordingly, in the plate center there are no restoring forces responding to deviations from planarity or from a particularly desired shape. Furthermore the thickness of the gas film is very sensitively dependent on the magnitude of the pilot pressure and other process parameters. Disruptions in these latter parameters can therefore cause warping of the plates.
U.S. Pat. No. 3,607,198 describes a device for contactless retention and transport of a hot glass plate on an air cushion that is built up above a solid base. Here, by arranging inlet-air slits and outlet-air slits successively alternating along the transport route zones with static and dynamic gas pressure are created, each extending over the entire width of the glass plate. Since here the gas delivery is effected via narrow slits with large interstices between them, the result is a gas supply that is locally very inhomogeneous, which in turn—because of the alternation between zones of high and low gas speed—makes it difficult to obtain a homogeneous temperature profile in the glass. Moreover, an expensive structure is employed, which is not suitable for use in the range of temperatures around 950° C., and certainly not for higher temperatures of up to about 1250° C. which can be necessary for ceramicization, because of considerations regarding the materials that are used.
U.S. Pat. No. 5,078,775 also discloses a device for contactless support and transport of a flat glass plate, in the tempering of float glass, on an air cushion that is built up above a solid base that likewise has alternating inlet-air and outlet-air slits. This known device, despite modifications in details, relies on the fundamental concept of U.S. Pat. No. 3,607,198, with the inlet-air and outlet-air slits in the base, and thus with regard to ceramicization applications has comparable disadvantages.

Method and device for retaining and transporting flat glass in a contactless manner


A terrain profile for executing terrain following flight is generated using a minimal volume of digital terrain elevation data (DTED) information. By limiting the amount of information considered in generating the terrain profile, the computational time and resource requirements for terrain profile generation are reduced, but without compromising the integrity of the terrain profile generated. The sample region is limited by limiting the width of sample regions according to expected use including most likely terrain following flight command data, potential unexpected flight path deviation, and long range terrain following flight data.

The present invention relates generally to terrain following aircraft control, and more particularly to a method for accessing and utilizing terrain elevation data in the context of terrain following flight.
To minimize above ground elevation, and therefore minimize visibility and vulnerability to ground based detection and attack, military aircraft often execute terrain following flight. Terrain following flight generally maintains a given elevation above ground level independent of actual elevation above sea level. In other words, the aircraft follows the ground contour at a substantially fixed elevation above the ground and maneuvers according to prevailing ground contour along a given flight path. The actual above ground level elevation may increase to establish a suitable climb angle to clear an upcoming high elevation terrain feature.
The general algorithm applied to flight following terrain is to select the tallest terrain feature lying along and near the flight path. The aircraft altitude and attitude vector are referenced to determine whether or not an upcoming terrain feature will be cleared. If necessary, the terrain following algorithm requires that the aircraft enter a suitable climb angle to clear any upcoming terrain features. Otherwise, the algorithm would maintain a substantially consistent above ground elevation according to a given terrain profile data structure.
As used herein, the term "terrain profile" shall refer to a data structure representing terrain along a given flight path. A terrain following algorithm uses the terrain profile data structure to execute terrain following flight along the designated flight path. A terrain profile may be thought of generally as a terrain cross-sectional, elevational contour, e.g., as taken through a vertical plane containing the flight path, but must account for terrain conditions near the designated flight path. For example, for a given point along the flight path, the highest elevation point laterally outward on either side a given distance is assigned as the terrain profile elevation at the given point. This produces a conservative, i.e., safe, elevation contour in the terrain profile.
Most terrain following applications use radar and/or ladar sensor data to generate a terrain profile along a predicted flight path of the aircraft. The predicted flight path is generally based on the current aircraft attitude and velocity. Terrain following flight is preferably executed, however, with limited or no active sensor data because active sensor emissions make the aircraft visible to threat installations at greater distances. Using active sensors, especially at high power, compromises covert missions because the aircraft can be detected at long distances by hostile forces. If active sensors are to be used, such sensors are preferably used at low power settings to minimize detectable emissions and allow only short range detection by hostile forces. Unfortunately, terrain following flight requires more distant terrain information, typically exposing the aircraft to detection if generated using long range high power active sensors. Furthermore, active sensor data has its limitations. Sensor data alone cannot see behind hills or around corners. Sensors can only "guess" where to gather terrain data in generating a terrain profile.
Digital terrain elevation data represents surface elevation at discrete "data posts." Each data post has a surface location or address, e.g. latitude and longitude, and an associated elevation, e.g. relative to sea level. Thus, a simple form of a DTED database would deliver a scalar elevation datum in response to longitude and latitude address input. More complicated DTED databases have been developed for certain applications. For example U.S. Pat. No. 4,899,293 issued Feb. 6, 1990 to J. F. Dawson and E. W. Ronish shows a tessellation method for creating a spherical database by warping a digital map, including digital terrain elevation data, by longitude and latitude parameters.
DTED database systems are used in flight mission computer systems and flight planning strategy in military applications aid in, for example, covert and evasive flight operations. As used in mission computer systems, a DTED database can aid a pilot in time-critical maneuvers such as terrain following flight or in selecting routes evasive with respect to a given threat position. Such threat positions may be known in advance, or detected while in flight. The computation speed required in accessing and calculating routes or alternatives based on DTED can be vitally critical, especially for repeated computations required to keep a pilot fully appraised of current terrain conditions and route alternatives. Thus, improvements in methods of accessing DTED and computations based on extracted DTED are not simply improvements in computational elegance, but can be life-saving and critical to mission success.
Terrain profiles have been built by extracting a massive volume of DTED data with reference to a designated flight path. As may be appreciated, each data sample taken from the DTED database for consideration in generating the terrain profile requires a given amount of processing time. The data extracted from the DTED database for generating the terrain profile corresponded to data posts lying along a length of the flight path preceding aircraft position and all data posts within a given distance of that length portion, i.e. a fixed length and width region of data posts along the flight path and identified relative to current aircraft position. The terrain profile must provide safe, conservative information. To this end, a large volume of DTED data has been incorporated into terrain profiles. Unfortunately, the volume of data extracted and processed has constrained terrain profile generation, i.e., has required excess terrain profile calculation time.
Thus, prior methods of generating terrain profiles include long range active sensors, but long range sensor emissions make aircraft visible at long distances, and DTED database systems, but generating conservative terrain profiles requires massive DTED data points and can require relatively long calculation time.
It is desirable, therefore, that terrain following flight be executed without aid of high power, long range active sensor data to avoid exposing the aircraft to threat installations. It is further desirable that a method of producing a terrain profile for executing terrain following flight support dynamic and efficient calculation time.


The present invention provides filter-based assays for measuring binding of compounds to phosphodiesterases (PDEs). The assay permits stoichiometric binding of compounds to PDEs, thereby providing a highly sensitive measure of a PDE binding and inhibition.

1. Field of the Invention
The present invention relates generally to the fields of enzymology and cell biology. More particularly, it concerns methods for assessing phosphodiesterase function.
2. Description of Related Art
Phosphodiesterase-5 (PDE5), which specifically degrades cGMP, is the target of sildenafil (Pfizer tradename Viagra®) in causing penile erection (Boolell et al., 1996; Corbin & Francis, 1999). PDE5 is present in high levels in smooth muscle tissues, but it is also present in platelets and other tissues (Francis et al., 1990; Francis et al., 2001). PDE5 is believed to contain a single catalytic domain and regulatory domain on each of two subunits. The catalytic domain is highly specific for cGMP, and it is homologous to those of the other family members of the superfamily of cyclic nucleotide phosphodiesterases (PDE) (McAllister-Lucas et al., 1993). The regulatory domain contains two GAF domains (Aravind & Ponting, 1997; McAllister-Lucas et al., 1993; Thomas et al., 1990a) (GAF=cGMP-Anabaena adenylate cyclase-Escherichia coli FhIA), at least one of which functions as a highly selective allosteric site for cGMP binding (Liu et al., 2001a; McAllister-Lucas et al., 1993). Four other PDE families (PDE2, PDE6, PDE10, and PDE11) also possess GAF domains (Charbonneau, 1990; Charbonneau et al., 1990; Fawcett et al., 2000; Francis et al., 2001; Fujishige et al., 1999; Soderling et al., 1999). In addition to PDE5, two other PDE families (PDE2, PDE6) have been shown to bind cGMP (Stroop & Beavo, 1991; Yamazaki et al., 1980).
Binding of cGMP to the GAF domains of PDE2 stimulates catalytic activity of this enzyme (Beavo et al., 1971). The regulatory domain in PDE5 is phosphorylated by cGMP-dependent protein kinase (PKG) at Ser-92 (bovine) both in vitro and in intact cells (Mullershausen et al., 2001; Murthy, 2001; Rybalkin et al., 2002; Thomas et al., 1990b; Wyatt et al., 1998). Regulation of phosphorylation of this site is substrate-directed since occupation of a GAF domain by cGMP is required for phosphorylation by PKG. Phosphorylation causes stimulation of both catalytic activity and cGMP binding to the GAF domain (Corbin et al., 2000; Francis et al., 2002).
It has been proposed that these effects are responsible for negative feedback regulation of active cGMP levels in cells. For both the cGMP and cAMP signaling pathways, negative feedback regulation has emerged as a major function of PDEs. PDE3 and PDE4 have been reported to be activated by phosphorylation when cAMP is elevated in cells (Conti, 2000; Degerman et al., 1997). Likewise, elevation of cGMP has been shown to cause increased PDE5 activity that is associated with cGMP-sensitive phosphorylation (Mullershausen et al., 2001; Murthy, 2001; Wyatt et al., 1998). In each case, PDE phosphorylation correlates with increased degradation of cyclic nucleotide. Elevation of cGMP is required for phosphorylation of PDE5 by PKG or cAMP-dependent protein kinase (PKA), and this process stimulates degradation of cGMP as well as sequestration of cGMP in the GAF domain (Corbin et al., 2000), both of which represent negative feedback on the cGMP pathway.
Negative feedback regulation of cGMP would be enhanced if cGMP binding to the GAF domain also directly stimulates the catalytic domain. This was predicted earlier from the principle of reciprocity (Thomas et al., 1990a; Weber, 1975; Francis et al., 1990). Binding of 3-isobutyl-1-methylxanthine (IBMX) or a similar ligand to the catalytic domain has been shown to stimulate binding of cGMP to a GAF domain, but direct evidence that binding of cGMP to a GAF domain stimulates the catalytic domain has been elusive. This has been due in large part to difficulties in performing such studies with PDE5, in which both the catalytic domain and GAF domain possess high specificity for cGMP. Okada & Asakawa recently reported that cGMP stimulates PDE5 catalytic activity when measured using a fluorescent cGMP analog that is specific for the catalytic site of the enzyme (Okada & Asakawa, 2002). They suggested that this stimulation occurs through cGMP binding to the GAF domains.
Studies of the catalytic domain of PDE5 would be greatly enhanced by a specific, high-affinity PDE5 catalytic-site radioligand that binds with sufficient affinity to allow isolation of the ligand-enzyme complex. In addition, binding assays based on this interaction could be used to screen for potentially efficacious PDE inhibitors. Properties of the catalytic site that are not directly dependent on catalytic activity could also be examined using such a ligand.


Embodiments of the present invention disclose a method and an apparatus for retrieving transmit opportunity control in reverse direction grant, so that a conflict occurring between a case where an RD Initiator continues sending another frame to an RD Responder after retrieving TXOP control and a case where a terminal other than the RD Initiator sends a block acknowledgement to the RD Responder can be avoided. The method provided in the embodiments of the present invention includes: when an RD Initiator fails to correctly demodulate a frame sent by an RD Responder, retrieving, by the RD Initiator, TXOP control by using a PIFS if it is impossible for the RD Responder to enable an MU-MIMO mode, and retrieving, by the RD Initiator, the TXOP control by using a duration if it is possible for the RD Responder to enable the MU-MIMO mode, where the duration is longer than the PIFS.

A basic service set (BSS) is a basic element of a wireless local area network (WLAN). A BSS network is formed by stations (STA) that have certain association within a specific coverage area. One scenario of the association is that stations directly communicate with each other in an ad hoc network, which is called an independent BSS (IBSS). Another common scenario is that in a BBS network, only one central station for dedicatedly managing a BSS is called an access point (AP), whereas other stations that are not an AP are called terminals, or called non-AP STAs. The AP and non-AP STAs are collectively called STAs. The AP and non-AP STAs do not need to be distinguished in description of the STA. In the same BSS network, due to factors such as a distance and transmit power, one STA is incapable of detecting another STA that is far away from it. The two STAs are hidden nodes for each other.
In the 802.11e protocol, a transmit opportunity (TXOP) is introduced. A TXOP is a bounded time interval during which a station may transmit a frame in a specific communication category. The station obtains a TXOP through contention. Once obtaining the TXOP, the station may transmit a frame in a specific communication category within the TXOP. The frame may specifically be a data frame, a control frame, or a management frame.
When a certain STA obtains a TXOP through contention, the STA is called a TXOP holder. A technology that within the TXOP, when the TXOP holder does not transmit data itself, the TXOP holder temporarily transfers TXOP control to another STA, and the another STA is enabled to send data to the TXOP holder is called reverse direction grant (RDG). In the RDG, the TXOP holder is called a reverse direction initiator (RD Initiator), and the STA that temporarily obtains the TXOP control granted by the RD Initiator is called a reverse direction responder (RD Responder).
To fully use a spectrum resource and improving a transmission rate, a TXOP sharing mode of multi-user multiple input multiple-output (MU-MIMO) is defined for downlink data of an AP. In this TXOP sharing mode of the MU-MIMO, multiple service types may share one TXOP, so as to implement concurrent transmission of frames of multiple service types in an MU-MIMO mode, thereby greatly saving the spectrum resource.
In traditional RDG, when an RD Responder sends a last frame to an RD Initiator, or requires an RD Initiator to send a block acknowledgement for the frame, the RD Responder automatically returns TXOP control back to the RD Initiator.
If the RD Initiator correctly demodulates the last frame sent by the RD Responder, the RD Initiator immediately retrieves the TXOP control. When the RD Responder sends a block acknowledgement request (BAR), the RD Initiator returns a block acknowledgement (BA) to the RD Responder. When the RD Initiator fails to correctly demodulate a block acknowledgement frame, the RD Initiator retrieves the TXOP control by using a point coordination function inter-frame space (PIFS). Retrieving the TXOP control by using the PIFS means that when the RD Initiator fails to correctly demodulate a frame, and does not know whether the frame is a last frame and whether a block acknowledgement is needed for the frame, within one PIFS, the RD Initiator intercepts a state of a channel (busy or idle). If the channel is in an idle state within the PIFS, the RD Initiator retrieves the TXOP control.
Based on the traditional RDG, when the RD Responder is an AP that supports the MU-MIMO, the AP may use an MU-MIMO technology to improve the transmission rate. For example, in a specific scenario, existing stations are an AP, an STA1, and an STA2. The STA1 and the STA2 are hidden nodes for each other, the RD Initiator is the STA1, and the RD Responder is the AP. When the AP enables the MU-MIMO, concurrently sends a frame to the STA1 and the STA2, and requires the STA2 to send an acknowledgement in time, if the STA1 fails to correctly demodulate the frame, the STA1 retrieves TXOP control by using a PIFS and then continues sending another frame to the AP. However, in this case, the STA2 sends a BA to the AP according to a requirement of the AP. That is, at the same time point, the STA1 sends another frame to the AP and the STA2 sends a BA to the AP, thereby resulting in a conflict.

This patent is subject to a terminal disclaimer.

Method and apparatus for retrieving transmit opportunity control in reverse direction grant


Disclosed herein are methods and systems that allows a user, when entering a string of input characters, to remove multiples input characters at one time back to where a typographical error occurs in the string. The method offers improvement over the current character-by-character deletion method where a user hits a deletion key multiple times to remove input characters that include the typographical error.

After a user inputs a sequence of characters, an error may be identified being in the middle of the sequence of characters. Currently, a user can correct the entire sequence of characters via an auto-correction function, which sometimes fails to provide replacement words that accurately reflect what the user intends to input. A user can also manually delete, character-by-character, the characters up to the position where an input error starts.
What is needed in the art are methods and systems that allows a user to efficiently delete characters corresponding to an input error and restart/continue inputting characters.

Intelligently deleting back to a typographical error


A device for bowing the brim of a cap and for storing, transporting, washing and/or displaying such cap having a body portion with first and second retention arms extending upwards at each end thereof forming first and second receipt areas at their junctions for receipt therein of the first side and second side of the cap brim, to form such brim into a desired curve. Notches can be disposed inward of each of the receipt areas for receipt of one side of the brim to form alternate brim receipt areas for different desired brim curvatures.

1. Field of the Invention
The device of this invention resides in the area of bowing devices for imparting a desired curve to a bendable structure and more particularly relates to a device into which the brim of a cap is positioned to bend the cap brim into a desired curved shape and which cap is retained in the device until the brim can maintain such curved shape on its own with such device also useful for transporting and storing the cap to maintain the brim in such desired curved shape.
2. Description of the Prior Art
Baseball caps are well known and generally have a fabric dome structure which fits over the head and a brim or visor extending from the front thereof which brim is made of a fabric covering stitched to a cardboard or plastic insert. When a baseball cap is purchased, the brim is a flat, planar member; and many purchasers will initially bend the brim manually to put a curve in it. Some individuals desire to have a more evenly curved brim than can be achieved by means of hand manipulation.
Most brim-bending methods of the prior art are not specifically adapted to put a neat, symmetrical curve in a baseball cap brim. In the prior art a curve is commonly accomplished by placing a somewhat rounded object, such as a baseball glove, under the brim and then curving the brim around the glove. Elastic bands are then placed around the brim and glove to have the brim form a desired even curve and be retained in that position until the brim takes on the desired curve on its own to maintain the brim in such curved shape. Other methods of curving a baseball cap brim are known such as using paper clips to clip the sides of the brim together. Another method requires that the brim be bent before turning the brim inside the cap and partially pulling it through the opening typically found in the rear of a baseball cap to hold the brim in such bent position until the brim retains a curve on its own. Formed wire devices in which caps can be washed and dried are also known. Once a desired curve has been imparted to the brim, such curve is often difficult to maintain over time. For example, if one packs a cap having a brim in a suitcase, during travel pressure from the other contents in the suitcase against the curved brim may cause the brim to flatten out.

Cap brim shaping, transport, storage and display device


A ski pole grip having an integral shell for protecting one's hands during a fall and more specifically for precluding one's thumb from being injured especially from extending outwardly and thereby bearing the brunt of impact during a fall, is disclosed. The shell partially surrounds the grip and is attached to the grip at the top and bottom thereof. The grip and shell are preferably molded in one integral piece with the shell in an inverted position. The shell is folded down to partially surround the grip--it is then in its use configuration and can be inserted onto a ski pole.

Skiing is one of the most popular sports in the world and is participated in both recreationally and competitively by millions of people in many countries throughout the world.
One of the reasons that skiing is so popular is that it is a very physically stimulating and thrilling activity involving high speeds--depending on one's skill level--and also involving many types of movements. Indeed, the essence of skiing is to generally push one's self to do as much as possible and therefore gain as much excitement and enjoyment as possible for one's own skill level.
For example, a beginner will ski down a hill having a shallow decline, which typically has very few bumps or turns, at a fairly low speed and generally without doing anything more than making very shallow turns. While this is not as physically challenging in terms of forces generated as more advanced type of skiing, it is often just as challenging to a beginner as competitive skiing might be to an experienced skier. In essence, what the beginner is doing even at this simple level, is to push his own abilities to the limit and make movements that may cause him to be in a situation that he does not have the skill level to handle, and resultingly the skier will probably fall.
As a beginning skier learns to perform basic maneuvers with confidence, other maneuvers--or similar maneuvers at higher speeds --are attempted. This is done in order to maintain a high level of excitement while skiing. Resultingly, even a more advanced skier is often prone to falling because he is pushing himself to his skill limits by performing new and more difficult maneuvers. Even in the case of advanced or professional skiers, maneuvers are performed that push a skier's skills to the limit. Further, these maneuvers are performed at high speeds. Resultingly, experienced and professional skiers fall occasionally, especially during competitive skiing where one is truly skiing at the limits of one's skill.
In any case, irrespective of the level of ability of a skier, there is a very good chance that any skier will fall at least occasionally. While beginning skiers typically fall more often, and are therefore more frequently exposed to the possibility of injury, more advanced skiers are usually going faster when they fall and therefore may be prone to more severe injury.
Further, skiing is done in an often slippery environment, which makes falling all the more likely.
It has been found that indeed most injuries in skiing are due to falling. Recent statistics indicate that the injury rate is about 3.3 injuries per 1000 skier days. In actuality, it is established that about 40% of downhill skiing injuries go unreported and that the injury rate may even be as high as 10 injuries per 1000 skier days. This translates to possibly as many as 5 million skiing related injuries in the world each year. This statistic has decreased in the last 20 to 30 years partially due to improved equipment such as the skies and boots. Most of the reduction in the injury rate is due to a decrease in lower extremity injuries.
The frequency of upper extremity injuries has not changed significantly, and statistics indicate that slightly under one-half of all skiing injuries are to the upper extremities; and moreover, that 85% of upper extremity injuries are thumb injuries. While at first this may seem slightly unusual, it can be well understood given the nature of how a skier generally tends to fall, and moreover, how a skier generally tends to defend himself when falling. It has been found that most often during a fall a skier will extend his or her arms and hands as a defense against the fall. When a downhill skier falls he typically does not have time to let go of the poles, or even if he does relax his grip on the poles, the poles generally remain within his hands. As the skier gets closer to the ground during the fall, the basket end of the poles usually trails behind which manages to tilt the hand in the forward direction of the thumb. As the skier outstretches his hands to help break the fall, the grip portion of the pole of the ski acts to isolate the thumb from the rest of the fingers which helps leave the thumb exposed and therefore vulnerable to impacting the snow.
Unfortunately, due to the direction of travel of the skier and the specific orientation of one's thumb when one's arms and hand are extended forwardly, the thumb is not designed to bend in the direction of the forces experienced on impact with the snow. In order words, most people's thumbs cannot bend back enough to absorb the impact of the forces experienced. Injury can therefore easily occur when the hands and arms hit the snow, especially at high speeds. Typically, a strong valgus force (bending back) occurs on the thumb, which strains the ulnar colateral ligament. Occasionally there is even a fracture at the base of the first phalanx joint of the thumb.
It has been found that it is very common to have one's thumbs protruding in an extended position, rather than somewhat covered in a closed position. Very commonly --as indicated by the 85% thumb injury rate--thumb impacts directly in the snow. Such injuries are apparently more common if the skier is still holding onto the ski pole. It is generally assumed that the ski pole is in some way responsible for the high frequency of thumb injuries in skiing, since other forms of sport where forward falls are common do not have a high frequency of thumb injuries.
A device that could preclude one's thumb from protruding outwardly while holding a ski pole grip and also that would protect one's thumb from direct impact with snow during a fall could potentially help a skier avoid--or at least lessen the risk of--thumb injuries while skiing.


A customizable dental appliance adapted to lie within the mouth of a person including of occlusal posterior pads optionally with a connective arch or a u-shaped style base with upstanding labial and/or buccal walls. The appliance is made of low-density polyethylene.

This invention relates to dental appliances and mouthguards, and more particularly to customizable dental appliances and mouthguards.
It is well known that athletes who are in contact sports wear mouthguards to protect their teeth from sharp blows as well as to protect the head and temporomandibular joint from concussion. Mouthguards are common in football, hockey, soccer, rugby, boxing, for example. Mouthguards may be considered a subgroup of dental appliances.
There is also a trend for athletes, such as body builders, weight lifters, baseball batters, golfers, football players, hockey players, and bowlers to wear dental appliances to prevent the clenching of their teeth during exertion which results in hundreds of pounds of compressed force exerted from the lower jaw onto the upper jaw. Teeth clenching also occurs in bruxing and child birthing. Clenching can result in headaches, muscle spasms, damage to teeth and injury to the temporomandibular joint as well as pain in the jaw. Thus, dental appliances have been created having posterior pads to be positioned between the upper and lower teeth to prevent clenching and damage to one""s teeth and jaw structures.
It also is well known that there are dental appliances for a myriad of other uses. Splints, which look like mouthguards, are used for bleaching of teeth, while other appliances may be used to control breathing and snoring. Dentists also use appliances in administering to teeth during dentistry.
Dental appliances and mouthguards historically have been made of ethylene vinyl acetate (EVA). These devices are subject to degradation due to the user clenching and chewing on the appliance or mouthguard. EVA also has a mild ester-like odor and cannot be made clear but rather translucent to white.
Upon decomposition, EVA will break down to hazardous vinyl acetate, acetic acid, carbon monoxide and hazardous hydrocarbon oxidation products.
There is a need for dental appliances to be made of clear material for aesthetics, have low or no odor and exhibit strong flexible, tensile and impact properties.
A customizable dental appliance adapted to lie within the mouth of a person consisting of occlusal posterior pads optionally with a connective arch or a u-shaped style base with upstanding labial and/or buccal walls. The appliance is made of low-density polyethylene with a nucleating agent.
A principle object and advantage of the present invention is the appliance is made of low-density polyethylene which exhibits no odor and strong flexible, tensile and impact properties while yet being soft.
Another object and advantage of the present invention is that the customizable appliance may be made clear for aesthetics.
Another object and advantage of the present invention is that the nucleating agent permits the softened appliance to shrink onto the teeth and gums for a tight fit.
Another object and advantage of the present invention is that the appliance is non-hazardous.
Another object and advantage of the present invention is that the nucleating agent adds gloss and clarity to the appliance.
Another object and advantage of the present invention is that the nucleating agent increase the crystalline temperature so that the appliance will harden quicker for a better customized fit.
Another object and advantage of the present invention is that the agent has anti-slip properties that make the appliance easy to mold.
Other objects and advantages will become obvious with the reading of the following specification and appended claims with a review of the figures.

Low-density polyethylene dental appliance and mouthguard with nucleating agent


Techniques and examples of hybrid automatic repeat request (HARQ) buffer size design for communication systems are described. A user equipment (UE) communicates with a serving cell of a wireless network using a HARQ mechanism, with the communicating involving: (a) determining, by the processor, a respective size of each buffer of a plurality of buffers corresponding to a plurality of HARQ processes on a per-HARQ process basis; and (b) storing, by the processor, respective information in each buffer of the plurality of buffers for a corresponding HARQ process among the plurality of HARQ processes.

Unless otherwise indicated herein, approaches described in this section are not prior art to the claims listed below and are not admitted as prior art by inclusion in this section.
In communication systems, HARQ is typically used to enhance reliability of communications to minimize negative impact due to potential corruption of a communication link between a transmitter and a receiver. In HARQ-based communications, only part of encoded bits are sent in each transmission as managed by a corresponding HARQ process. There are costs associated with HARQ-based communications in terms of storage and decoding complexity. With respect to storage, the receiver needs to buffer received bits for decoding if one or more previous transmissions failed. With respect to decoding complexity, for low-density parity-check (LDPC) decoders, decoding complexity relates to the number of coded bits. Both aspects of costs are related to the buffer size of a HARQ process.

HARQ buffer size design for communication systems


The oxidation of isobutyraldehyde produces isobutyric acid and byproducts, such as isopropyl formate. A method of reducing the isopropyl formate byproduct in the oxidation of isobutyraldehyde is described. The method uses a co-solvent, such as acetone, to the isobutyraldehyde feed to increase both the selectivity of the reaction to isobutyric acid and the production rate of isobutyric acid so that the isopropyl formate byproduct is significantly reduced.

Production of isobutyric acid (iHOBu) is accomplished by the catalyzed or uncatalyzed oxidation of isobutyraldehyde (iHBu). FIG. 1 illustrates that the oxidation of the aldehyde results in the formation, first of peroxyacid, followed by the generation of an intermediate that can lead to production of two moles of the desired acid (Pathway A), with an undesired by-product, isopropyl formate (IPF), produced by the Bayer-Villager oxidation of isobutyraldehyde (Pathway B).

As seen in FIG. 1, iHBu can form either the desired acid or the undesired byproduct IPF. In Pathway A, the movement of electrons from a C—H bond on the peroxy acid-aldehyde intermediate results in the formation of two moles of the desired carboxylic acid product. In Pathway B, the electrons move from a C—C bond on the intermediate to form one mole of iHOBu and one mole of the undesired IPF byproduct. Low selectivity for Pathway A results in the loss of some of the iHBu feed to form of the undesired byproduct IPF. In view of problems associated with low selectivity of iHBu oxidation, it would be beneficial if Pathway B of the oxidation mechanism could be impeded so that less byproduct IPF will be produced and more desired acid will be produced.
IPF not only consumes valuable raw materials and lowers the production of the desired acid, it also has other drawbacks. For example, IPF byproduct is very difficult to be separated from unreacted starting materials. The separation of IPF from the reaction mixture is usually accompanied by unreacted isobutyraldehyde (iHBu) due to the proximity of their boiling points. Accordingly, the formation of IPF by-product is a significant financial burden on commercial production of isobutyric acid.

Reduction of ester formation in isobutyraldehyde oxidation


A trailer backup assist system for a vehicle, according to one embodiment, includes a trailer coupled with the vehicle. The trailer of the trailer backup assist system has a braking system. The trailer backup assist system also includes a sensor that senses a hitch angle between the vehicle and the trailer. In addition, the trailer backup assist system includes a steering input device that provides a desired curvature of the trailer. The trailer backup assist system further includes a controller generating a steering command based on the hitch angle for the vehicle to guide the trailer on the desired curvature and an actuation command for the braking system to reduce a rearward travel distance for the trailer to achieve the desired curvature.

Reversing a vehicle while towing a trailer can be challenging for many drivers, particularly for drivers that drive with a trailer on an infrequent basis or with various types of trailers. One reason for such difficulty may be that backing a vehicle with an attached trailer requires steering inputs that are opposite to steering inputs when backing the vehicle without a trailer attached to the vehicle. Another reason for such difficulty may be that small errors in steering while backing a vehicle with an attached trailer are amplified, which may cause the trailer to quickly depart from a desired path. Yet an additional reason backing a trailer can prove to be difficult is the need to control the vehicle in a manner that limits the potential for a jackknife condition to occur. These difficulties may also be experienced and in some instances increased when attempting to quickly achieve a tight turning radius or when switching between various trailers that have a wide variance in how they react to similar steering inputs, such as how a relatively short trailer may react quicker to a steering change than a longer trailer.

Trailer backup assist system with active trailer braking for curvature control


A distributed cell field-effect transistor (FET) amplifier (40) includes a plurality of parallel, elongated source (46a) and drain (46b) regions of individual FET unit cells (46) formed in a substrate (42) in transverse alternating relation, with a plurality of elongated channel regions (46c) being formed between and parallel to adjacent source (46a) and drain (46b) regions respectively. A source foot (48) and a drain foot (50) extend perpendicular to the source (46a) and drain (46b) regions on opposite longitudinally spaced sides thereof respectively. A gate foot (52) extends parallel to the source (48) and drain (50) feet, between the source foot (48) and the cells (46). Source (54) and drain (56) pads and gate (58) fingers extend from the source (48), drain (50) and gate (52) feet into electrical connection with the respective source (46a), drain (46b) and gate ( 46c) regions respectively. The source pads (54) include airbridge portions (54b) which extend over the gate foot (52) without making contact therewith. A fixed tuning circuit (70) is connected between the gate foot (52) and source foot (48), including an inductive stub (72) having a first end connected to the gate foot (52) and a second end, and a capacitor (74) having a first plate (74a) which is integral with the source foot (48) and a second plate connected to the second end of the stub (72). The integration of the capacitor (74) with the source foot (48) enables the amplifier (40) to be tuned at the gate foot (52), thereby eliminating undesirable coupling effects and the need for a separate via for the tuning circuit (70).

1. Field of the Invention
The present invention generally relates to the field of high frequency electronic signal amplifiers, and more specifically to a monolithic microwave integrated circuit (MMIC) field-effect transistor (FET) amplifier.
2. Description of the Related Art
Monolithic microwave integrated circuits on gallium arsenide (GaAs) and other semi-insulating substrates enable active array radar, communications and other systems to be produced which are compact, lightweight, provide high performance and can be manufactured inexpensively on a commercial production basis. A general treatise on MMICs is presented in an article entitled "MMIC Technology: Better Performance at Affordable Cost", in Microwave Journal, April 1988, pp. 135-143.
Distributed circuit arrangements are employed in MMIC amplifiers to increase the power handling capability. This is accomplished by fabricating a plurality of amplifier unit cells on a substrate and interconnecting them in a parallel interdigitated configuration.
An example of such a prior art MMIC amplifier is illustrated in FIG. 1 and generally designated as 10. The amplifier 10 includes a plurality of transversely spaced metal-semiconductor field effect transistor (MESFET) unit cells fabricated in a GaAs substrate, each including doped source, drain and channel regions which are not visible in the drawing. The amplifier 10 further includes a plurality of parallel, elongated drain pads 14 which overlie the drain regions of the MESFET cells in electrical connection therewith. The right ends of the drain pads 14 are interconnected by a drain foot 16 which enables the drain pads 14 to be collectively connected to external circuitry.
A plurality of source pads 18 are interspersed between the respective drain pads 14 in electrical connection with the source regions of the MESFET cells. A plurality of gate fingers 20 are interspersed between the respective drain pads 14 and source pads 18 in electrical connection with the respective channel regions of the MESFET cells, and interconnected at their left ends to a gate foot 22.
Source connection pads 24 and 26 are provided at the upper and lower ends of the amplifier 10, and connected to a ground plane (not shown) on the opposite side of the substrate 12 by electrically conductive vertical interconnects or vias 28 and 30 respectively. The source pads 18 are connected to the source connection pads 24 and 26 by an electrically conductive airbridge 34 having first portions 34a which are ohmically bonded to the source pads 18 and second portions 34b which extend over and are electrically isolated from the drain pads 14 and gate fingers 20.
The amplifier 10 has a common emitter configuration, with the source pads 18 grounded through the vias 28 and 30 and ground plane. An input signal is applied to the gate regions of all of the MESFET cells in parallel through the gate foot 22 and gate fingers 20, and an output signal is taken from the drains of all of the MESFET cells in parallel through the drain pads 14 and drain foot 16.
In this configuration, the total collector current flow through the amplifier 10 is distributed between the MESFET cells. However, due to the architecture of the amplifier 10, the electrical characteristics of the unit MESFET cells are different and the collector currents through the individual cells are also different.
More specifically, the source pads 18 are effectively connected to the source connection pads 24 and 26 in series through the airbridge 34. The source inductance, and thereby the inductive reactance and collector current varies between the unit cells, with the source inductance of the inner cells being higher than the outer cells. For am amplifier with a large number of cells, the source inductance of the inner cells can become excessive, thereby reducing the cutoff frequency of the amplifier.
The series connection of the source pads 18 to the source connection pads 24 and 26 also creates a phase difference between the signals propagating through the individual MESFET cells, thereby reducing the signal combining efficiency of the amplifier 10. The connection of the portions 34a of the airbridge 34 to the source pads 18 requires a relatively large amount of space, thereby increasing the spacing between the gate fingers 20 and further increasing the signal phase variation.
Further drawbacks of the arrangement of the amplifier 10 are that it occupies an inefficiently large amount of space on the substrate 12, and is limited to only high power applications.

Distributed cell monolithic mircowave integrated circuit (MMIC) field-effect transistor (FET) amplifier


A rotating electrical machine includes, a cooling circuit 4 is provided for introducing oil to inside a housing, for cooling an inner periphery and outer periphery of a slotless stator in that order. Moreover, there is also provided a cover plate for preventing back flow of the oil introduced to inside the housings, to an outer peripheral side of the slotless stator 1. As a result, oil which has just been introduced to the housing, and has not yet been supplied for cooling the heat source, is promptly circulated to the inner peripheral side of the stator which requires much more cooling, so that the temperature rise of the overall rotating electrical machine is effectively suppressed. Moreover, a part of the oil introduced to inside the housing is used for lubricating bearings supporting a rotor.

1. Field of the Invention
The present invention relates to a liquid cooled type rotating electrical machine with an improved circulating path for liquid coolant.
2. Description of the Related Art
Heretofore, as a liquid cooled type rotating electrical machine where cooling liquid is introduced into a housing, and a stator is cooled by the cooling liquid, there are known for example, the rotating electrical machines of Japanese Examined Patent Application, Second Publication No. Sho. 60-36696, and U.S. Pat. No. 4709180.
With the former rotating electrical machine, the stator body is cooled by the cooling liquid, while with the latter rotating electrical machine, the cooling liquid is circulated inside the rotor for cooling.
However, when an Nd-Fe-B magnet is used for the rotor, the generating efficiency is increased accompanying the high magnetic flux due to the large energy product. With an increase in temperature of the magnet itself however the magnetic force is reduced, and hence the generating efficiency drops.
On the other hand, in the case where electricity generation is carried out at high rotational speeds exceeding several ten thousand rpm, generating in the stator copper losses and eddy current losses produced in the winding section, and core losses produced in the core section, these losses are all converted to heat so that the stator comes into a high temperature condition.
Therefore, in order to realize high efficiency power generation, it becomes important to efficiently cool the inner periphery of the stator close to the rotor, so that the characteristics of the magnet are not impaired.
The present invention takes into consideration the above situation with the object of efficiently cooling the stator.
In order to achieve the above object, the present invention adopts the following devices.
That is, according to the present invention, a rotating electrical machine is provided, in which a cylindrical shape stator is accommodated inside a housing, a rotor is rotatably supported on an inner peripheral side of the stator, and a cooling circuit for introduces cooling liquid (oil with this embodiment) to inside the housing for cooling an inner periphery and an outer periphery of the stator in that order.
With this construction, low temperature cooling liquid which has just been introduced to the housing, and has not yet been supplied for cooling the heat source, is promptly circulated to the inner peripheral side of the stator which requires much more cooling than the outer peripheral side of the sator.
Therefore, it becomes possible to efficiently cool the stator using the low temperature cooling liquid. Hence the temperature rise of the overall rotating electrical machine is suppressed.
Furthermore, with the above construction, in the case where there is provided a non return device (a cover plate with this embodiment) for preventing back flow of the cooling liquid introduced inside the housing, to an outer peripheral side of the stator, the cooling liquid introduced to inside the housing is reliably conducted to the inner peripheral side of the stator close to the rotor before to being conducted to the outer peripheral side of the stator far from the rotor.
Furthermore, with either of the above constructions, in the case where the cooling liquid is also used for lubrication of bearings supporting the rotor, the circuit necessary for lubrication and cooling can be simplified.
Moreover, with any of the above constructions, with a stator winding where heat conducting particles (BN particles with this embodiment) are filled into the stator winding, and moreover when a resin such as varnish is also impregnated, into the stator winding this is impregnated with the heat conducting particles mixed into the impregnating resin and is then hardened, then the thermal conductivity of the impregnated resin portion is improved. Hence, heat dissipation of the stator winding is enhanced and the cooling efficiency is further improved.

Rotating electrical machine with improved circulating path for coolant


To enable network control (particularly, transmission band allocation) that excels in follow-up ability to follow changes in a network, locality, and responsiveness. A network control apparatus controls a wireless ad-hoc network and includes: a routing processing unit (402) which establishes routing within a wireless ad-hoc network using routing information including information regarding a local transmission quality within the wireless ad-hoc network; a routing processing unit (406) which obtains the information regarding the transmission quality from the routing information used for establishing the routing; and a bottleneck estimating unit (411) which estimates a relay apparatus as a bottleneck candidate, based on a distribution of plural transmission qualities within the wireless ad-hoc network, which are indicated by the obtained information.

Conventionally, a wireless ad-hoc network and a wired network are connected to each other at a gateway, and data is transmitted from plural sending terminals connected to the wireless ad-hoc network to respective receiving terminals connected to the wired network.
In the transmission, an effective band available for the data transmission between each of the sending and receiving terminals depends on routing from the sending terminal to the gateway and the network status, thus resulting in unfairness among the sending terminals.
In order to reduce such unfairness, various techniques are known for securing fairness in transmission band among plural sending terminals connected to the wireless ad-hoc network (for example, see Patent References 1 to 6).
Patent Reference 1 discloses a technique for detecting a bottleneck in the transmission band, which is generated at a relay node in the wireless ad-hoc network, so as to decrease a transmission rate at a source apparatus.
In addition, Patent Reference 2 discloses a technique for searching packet content at each relay node and scheduling an order of transmitting each packet.
In addition, Patent Reference 3 discloses a technique for prorating, at each relay node, a transmission band available for the relay node according to the number of terminals that are relayed (subordinate terminals) so as to achieve a fair data transmission amount among the subordinate terminals.
In addition, for a method of controlling the transmission amount for the sending terminals according to a communication band on a transmission path, Patent Reference 4 discloses a technique for estimating the transmission band for the communication network at a receiving side and indicating, to the sending terminals, the data transmission amount based on the estimated transmission band.
In addition, Patent Reference 5 discloses a technique for optimizing an update frequency of routing information by increasing the update frequency between unstable nodes or links, and decreasing, conversely, the update frequency between stable nodes or links. Patent Reference 5 further discloses a technique for estimating, at each relay node, stability (fault tolerance) of the nodes and links on the transmission path.
In addition, Patent Reference 6 discloses a technique for detecting a bottleneck link on the transmission path by obtaining, one by one, band information of each link between a sending terminal and a relay node, between relay nodes, and between a relay node and a receiving terminal, so as to perform transmission and reception according to the band of the detected link.                Patent Reference 1: Japanese Unexamined Patent Application Publication No. 2005-328458        Patent Reference 2: Japanese Unexamined Patent Application Publication No. 2006-74720        Patent Reference 3: Japanese Unexamined Patent Application Publication No. 2004-172719        Patent Reference 4: Japanese Unexamined Patent Application Publication No. 2000-115245        Patent Reference 5: Japanese Unexamined Patent Application Publication No. 2004-336768        Patent Reference 6: Japanese Patent No. 3662907

Network control apparatus, method, and program


A cell for the electrowinning of aluminium (50) from alumina dissolved in a molten electrolyte comprises a generally horizontal cell bottom (5), preferably aluminium-wettable, on which a pool of product aluminium (50) is collected from at least one electrically conductive cathodic element (10) having aluminium-wettable cathode surfaces (11). The cathodic element comprises an inclined cathodic wall (10) in the electrolyte (60) above the generally horizontal cell bottom (5). The cathodic wall (10) has an upwardly-oriented inclined face (11) that forms a sloping upper aluminium-wettable drained active cathode surface on which aluminium is produced and drains into the aluminium pool (50), and a downwardly-oriented inclined face (12) which is in contact with the molten electrolyte (60) and which overlies the aluminium pool (50). The aluminium pool (50) covers substantially the entire cell bottom (5) including underneath the cathodic wall (10). A return path for alumina-enriched electrolyte (60) towards a bottom end of the anode-cathode gap (40) may be provided behind the cathodic wall (10) along an inactive surface (12) thereof. The cell may be fitted with anodes (10) that are foraminate, e.g. an arrangement of spaced apart parallel rods, or solid plates.

The technology for the production of aluminium by the electrolysis of alumina, dissolved in molten cryolite containing salts, at temperatures around 950° C. is more than one hundred years old. This process and the cell design have not undergone any great change or improvement and carbonaceous materials are still used as electrodes and cell linings.
U.S. Pat. No. 3,400,061 (Lewis/Hildebrandt) and U.S. Pat. No. 4,602,990 (Boxall/Gamson/Green/Traugott) disclose aluminium electrowinning cells with sloped drained cathodes facing anodes sloping across the cell. In these cells, the molten aluminium flows down the sloping cathodes into a median longitudinal groove along the centre of the cell, or into lateral longitudinal grooves along the cell sides, for collecting the molten aluminium and delivering it to a sump.
In U.S. Pat. No. 5,362,366 (de Nora/Sekhar), a double-polar anode-cathode arrangement was disclosed wherein cathode bodies were suspended from the anodes permitting removal and reimmersion of the assembly during operation, such assembly also operating with a drained cathode.
U.S. Pat. No. 5,368,702 (de Nora) proposed a novel multimonopolar cell having upwardly extending cathodes facing and surrounded by or in-between anodes having a relatively large inwardly-facing active anode surface area. In some embodiments, electrolyte circulation was achieved using a tubular anode with openings.
U.S. Pat. No. 5,651,874 (de Nora/Sekhar) proposed coating components with a slurry-applied coating of refractory boride, which proved excellent for cathode applications. This publication discloses slurry-applied applications and novel drained cathode configurations, including designs where a solid cathode body with an inclined upper drained cathode surface is placed on or secured to the cell bottom.
U.S. Pat. No. 5,472,578 (de Nora) discloses an aluminium production cell comprising a grid on the cell bottom for restraining motion of the aluminium pool on the cell bottom. In some embodiments, the top end of the grid forms an aluminium-wettable drained cathode surface under an active anode surface.
WO00/40782 (de Nora) discloses aluminium production anodes with a series of coplanar parallel elongated anode members which are spaced-apart by flow-through openings and which form an electrochemically active surface. In one embodiment two downwardly converging spaced apart adjacent anodes can be arranged between a pair of substantially vertical cathodes. The adjacent anodes are spaced apart by an electrolyte down-flow gap in which alumina-rich electrolyte flows downwards until it circulates via the adjacent anodes' flow-through openings into the inter-electrode gaps.
WO01/31088 (de Nora) discloses aluminium electrowinning cells with solid anodes having a V-shaped active surface facing sloping cathodes. The anodes and cathodes are associated with vertical passages for the circulation of alumina-rich electrolyte to a bottom part of the inter-electrode gaps spacing the anodes and cathodes.
While the foregoing references indicate continued efforts to improve cell operations, none suggests the invention and there have been no entirely acceptable proposals for improving the cell efficiency, and at the same time facilitating the implementation of a drained cathode configuration with improved electrolyte circulation and large storage capacity of product aluminium.

Aluminium electrowinning cells with inclined cathodes


A wireless communication method embeds service related information, including a version of a service associated with the service related information, within an initial wireless access message. The method may also include broadcasting the initial wireless access message including the embedded service related information. Another aspect of the present disclosure includes a wireless communication method that indentifies service related information embedded within an initial wireless access message. The method may also establish a connection with an access node of the wireless communication network to receive a service when a version of a service associated with the service related information satisfies a predetermined condition.

Field
Aspects of the present disclosure relate generally to wireless communication systems, and more particularly to service discovery from wireless nodes before device discovery and connection establishment between wireless nodes.
Background
Wireless networks are widely deployed to provide various communication services such as voice, video, packet data, messaging, broadcast and other like wireless communication services. These wireless networks may be multiple-access networks capable of supporting multiple users by sharing the available network resources. In a wireless local area network (WLAN) an access point supports communication for a number of wireless stations within the wireless network. In an ad-hoc mode, the wireless stations communicate in a peer-to peer (P2P) manner without an access point. Similarly, a peer-to-peer network allows the peer nodes to directly communicate with one another. In a peer-to-peer network, peer-to-peer nodes within range of one another discover and communicate directly without an access point.
In implementations of wireless networks, nodes of the wireless networks discover each other and establish a connection before performing service discovery, which is referred to as the "connection prerequisite for service discovery." Service discovery may include information regarding any service related applications or data available from a wireless peer node. This connection prerequisite for service discovery introduces latency. In addition, the connection prerequisite for discovery of service related information consumes additional power.

Detecting services provided by a wireless node before device discovery and connection establishment


A device mounting structure includes: a base; a unit having a mounting area on which a device is mounted; a projection formed on a face of the unit; a first wiring disposed on the unit and between a top part of the projection and the mounting area; a groove provided in the base, the groove incorporating at least part of the projection; and a second wiring disposed at a bottom part of the groove in the base and electrically connected to the first wiring. The first wiring has a resin layer containing metallic particles, and a metal film on the resin layer.

1. Technical Field
The present invention relates to a device mounting structure, device mounting method, electronic apparatus, liquid droplet ejection head, and liquid droplet ejection apparatus.
2. Related Art
As a method for disposing and electrically connecting a drive device such as an IC chip on a circuit board, the wire bonding method has been known for some time now. For example, even with respect to liquid droplet ejection heads (ink jet recording heads) used in the case of application of the liquid droplet ejection method (ink jet method) when forming images and manufacturing micro devices, a wire bonding method is used to connect piezoelectric elements for conducting ink ejection operations and a drive circuit (IC chip or the like) for supplying electrical signals to the piezoelectric elements (for example, see Japanese Unexamined Patent Application, First Publication No. 2003-159800 and Japanese Unexamined Patent Application, First Publication No. 2004-284176).
In conjunction with the ever higher integration of IC chips and the like in recent years, there has been a tendency for the external connection terminal of the IC chip and the like to become ever narrower, and to be given an increasingly narrow pitch. In this regard, there has also been a tendency to give an increasingly narrow pitch to the wiring patterns formed on the base substrate. Consequently, application of a connection method using the aforementioned wire bonding has become increasingly difficult.
Moreover, with respect to methods conducting image formation and micro device manufacture based on the liquid droplet ejection method, in order to realize increasingly minute detailing of the image or miniaturization of the micro device, it is preferable to make the distance between the nozzle apertures provided in the liquid droplet ejection head (the nozzle pitch) as small (narrow) as possible. As piezoelectric elements are multiply formed corresponding to the nozzle apertures, if the nozzle pitch is made small, the distance between the piezoelectric elements must also be made small, corresponding to the nozzle pitch. If the distance between the piezoelectric elements is made small in this manner, connection of the plurality of respective piezoelectric elements and the driver IC by the wire bonding method is difficult.
Furthermore, in conjunction with the increasingly compact size of electronic apparatuses, there is a growing need to electrically connect the device and the wiring of the base substrate via a step difference of the IC chip or the like in the device, or a step difference derived from the formation of the base substrate.

Device mounting structure, device mounting method, electronic apparatus, liquid droplet ejection head, and liquid droplet ejection apparatus


The present invention teaches a LTPS TFT substrate and its manufacturing method. The manufacturing method, after forming vias using the photoresist layer on the ILD layer and the gate insulation layer above the source/drain contact regions, and before peeling the photoresist layer, forms conductive layers in the vias by depositing conductive material in the vias. The source/drain electrodes contact the conductive layers in the vias and therefore are conducted to the source/drain contact regions, thereby effectively resolving the problem of contact impedance being too high between the source/drain electrodes and the source/drain contact regions from the existing re-etch LDD technique. Then, through the re-etch LDD technique, the present invention is able to omit a mask process without sacrificing product characteristics. In addition, the vias and the photoresist layer have undercut structure, preventing the deposited conductive material from affecting the photoresist layer's peeling and guaranteeing the photoresist layer's peeling efficiency.

In the field of display technologies, liquid crystal display (LCD) and active matrix organic light emitting diode (AMOLED) are widely applied to mobile phones, personal digital assistants (PDA), digital cameras, computer screens, and notebook screens, due to their thin thickness, high quality, power saving, and low radiation.
Thin film transistor (TFT) array substrate is a key component to LCD and AMOLED devices, directly affecting the performance of these flat panel display devices. For the provision of driving circuit to the display devices, the TFT array substrate is usually configured with multiple gate scan lines and multiple data lines, jointly defining multiple pixel units. Each pixel unit is configured with TFT and pixel electrode. The gate of the TFT is connected to a corresponding gate scan line. When the voltage on the gate scan line reaches the threshold voltage, the source and drain of the TFT are conducted, and the voltage on the data line reaches the pixel electrode, thereby controlling the display of the corresponding pixel. Usually the TFT on the array substrate includes gate electrode, gate insulation layer, active layer, source and drain electrodes, and insulating protection layer, stacked on the substrate.
Compared to traditional amorphous silicon (a-Si) TFT, low temperature poly-silicon (LTPS) TFT, due to better carrier mobility, is widely applied to small- to medium-sized, high-resolution, LCD and AMOLED display panels, despite its more complex manufacturing process. LTPS is considered as an important material to achieve low-cost and full-color flat panel displays.
Hot carrier effect is a major factor causing metal oxide semiconductor (MOS) to fail. As MOS devices are continuously reduced in size, they suffer even severer hot carrier effect. To effectively control the hot carrier effect for LTPS N-type MOS (NMOS) devices so as to enhance their reliability and improve the leakage current under negative bias condition in LTPS array, existing LTPS NMOS adopts a lightly doped drain (LDD) method in the manufacturing process by providing a lightly doped region in the poly-silicon (poly-Si) ditch around the source and drain, and distributing some voltage to this lightly doped region.
Currently mostly applied LDD techniques are mask LDD and re-etch LDD. The process of manufacturing LTPS array substrate using mask LDD involves the following steps.
Step S10, as shown in FIG. 1, sequentially forms a buffer layer 200 and a poly-Si active layer 300 on the substrate 100, coats photoresist on the poly-Si active layer 300, and forms a photoresist pattern 980 using a mask through exposure and development, and forms source/drain contact regions 310 by implanting N-type ions of a high dosage (P+, 1×1014˜1×1015 ions/cm2) to two ends of the poly-Si active layer 300 using the photoresist pattern 980 as a shielding layer.
Step S20, as shown in FIG. 2, peels the photoresist pattern 980, forms a gate insulation layer 400 above the buffer layer 200 to cover poly-Si active layer 300 by deposition, deposits and patterns a first metallic layer on the gate insulation layer 400, forms a gate electrode 500 on the poly-Si active layer 300 above where a ditch region 320 to be located, and forms the ditch region 320 and LDD regions 330 between the ditch region 320 and the source/drain contact regions 310 by implanting N-type ions of a low dosage (P+, 1×1012˜1×1013 ions/cm2) to two ends of the poly-Si active layer 300 using the gate electrode 500 as a shielding layer.
Step S30, as shown in FIG. 3, forms an interlayer dielectric (ILD) layer 600 on the gate electrode 500 and the gate insulation layer 400 by deposition, coats a photoresist on the ILD layer 600, and forms a photoresist layer 900 by exposure and development.
Step S40, as shown in FIG. 4, forms vias 650 by etching the ILD layer 600 and the gate insulation layer 400 above the source/drain contact regions 310 to the two sides of the poly-Si active layer 300 using the photoresist layer 900 as a shielding layer.
Step S50, as shown in FIG. 5, deposits and patterns a second metallic layer on the ILD layer 600 to obtain source/drain electrodes 800. The source/drain electrodes 800 contact the source/drain contact regions 310 to the two sides of the poly-Si active layer 300 through the vias 650.
Unlike mask LDD technique, existing re-etch LDD technique performs two etching to the first metallic layer after patterning and forming poly-Si active layer 300, instead of conducting heavy doping to the poly-Si active layer 300 through the photoresist pattern 980. The metallic pattern after the first etching defines the source/drain contact regions 310 for heaving doping. Then heavy doping is conducted using the metallic pattern as a shielding layer towards the two sides of poly-Si active layer 300 by implanting N-type ions of a high dosage. Then, the first metallic layer is etched for a second time to obtain the gate electrode 500 and, using the gate electrode 500 as a shielding layer, light doping is conducted towards the two sides of the poly-Si active layer 300 by implanting N-type ions of the low dosage. Compared with the mask LDD technique, the main advantage of the re-etch LDD technique is to save a lithographic process, thereby saving the production cost and process time of a mask, and increasing productivity. The main drawback of re-etch LDD technique is that, when conducting heavy doping, N-type ions have to be implanted through the gate insulation layer 400. Within the existing workstation capability, most N-type ions cannot be implanted into the poly-Si active layer 300, causing low ionic content in the source/drain contact regions 310, resulting in abnormal contact impedance to the source/drain electrodes 800, and affecting device performance.

LTPS TFT substrate and manufacturing method thereof

Wuhan China Star Optoelectronics Technology Co., Ltd.


An echo cancellation detector for controlling an acoustic echo canceller that is configured to cancel an echo of a far-end signal in a near-end signal in a telephony system, the echo cancellation detector comprising a comparison generator configured to compare the far-end signal with the near-end signal, a decision unit configured to make a determination about a first acoustic echo canceller based on that comparison and a controller configured to control an operation of a second acoustic echo canceller in dependence on the determination.

This invention relates to echo cancellation in telephony. In telephony, audio signals (e.g. including voice signals) are transmitted between a near-end and a far-end. Far-end signals which are received at the near-end may be outputted from a loudspeaker. A microphone at the near-end may be used to capture a near-end signal to be transmitted to the far-end. An "echo" occurs when at least some of the far-end signal outputted at the near-end is included in the near-end signal which is transmitted back to the far-end. In this sense the echo may be considered to be a reflection of the far-end signal. An example scenario is illustrated in FIG. 1a, which shows a signal being captured by a far-end microphone and output by a near-end loudspeaker. The echo is a consequence of acoustic coupling between the loudspeaker and the microphone; the microphone captures the signal originating from its own loudspeaker in addition to the voice of the near-end speaker and any near-end background noise. The result is an echo at the far-end loudspeaker. Echo cancellation is an important feature of telephony. Hands-free devices and teleconferencing, in particular, require echo cancellation that can adapt to environments having a wide range of acoustic characteristics. In these examples, a combination of factors contributes to echo being more of an issue. First, the volume at which the far-end signal is outputted from the near-end loudspeaker is typically loud enough that the far-end signal is a significant part of the signal captured by the near-end microphone. Second, the physical arrangement of the loudspeaker and microphone in these types of arrangements tends to result in a good acoustic coupling between the two.
Acoustic echo cancellers typically synthesise an estimate of the echo from the far-end voice signal. The estimated echo is then subtracted from the microphone signal. This technique requires adaptive signal processing to generate a signal accurate enough to cancel the echo effectively. An adaptive filter is often used to model the environment's acoustic impulse response.
An acoustic echo cancellation application often forms part of a user application, such as VoIP (Voice over Internet Protocol) software. There is an increased demand for high definition voice quality in VoIP communications. Some mobile phone vendors now incorporate an acoustic echo canceller (AEC) into their platform audio interface, which is accessible to user applications. When a user application that implements acoustic echo cancellation runs on a platform that also implements acoustic echo cancellation, this can have a severe impact on voice quality. FIG. 1b illustrates an implementation in which the two are cascaded. Non-linear modules such as a noise canceller, non-linear processor, comfort noise generator and automatic gain controller in the platform AEC can negatively impact the operation of the user application AEC. For example, the user application AEC models the echo path impulse response during the presence of far-end voice. This may cause it to regenerate echo that was cancelled by the platform AEC. Also, periods of double talk (DT) may be distorted or chopped due to the application AEC adapting to the high far-end signal.
The user application AEC should preferably be disabled if it is operating on a platform that also has an AEC in its audio interface. Some device vendors recognise the problem and provide information indicating the presence of a platform AEC through the relevant application programming interface (API). This information can be used to turn the application AEC ON or OFF, as appropriate. This approach is unreliable, however, as it is entirely dependent on device vendors providing the AEC information. Therefore there is a need for an improved mechanism for detecting the presence of a platform AEC.