Apparatus and method for writing data to an optical disc, and for subsequently reading the data therefrom. A first modulation encoding scheme (MES1) is defined to encode input data as data symbols having nominal symbol lengths over a first range. A second modulation encoding scheme (MES2) different from the MES1 is further defined to encode input data as data symbols having nominal symbol lengths over a second range. Each symbol length of the second range appears in the first range. The MES1 is used to encode primary data written to the disc while the MES2 is used to encode secondary data inserted at selected locations for disc authentication purposes. A readback system includes a primary decoder which decodes and outputs the primary data, and a secondary decoder which searches for a leading synchronization pattern which, when detected, allows remaining portions of the secondary data to be decoded.

This invention relates generally to the field of optical disc technology and more particularly, but not by way of limitation, to the placement and retrieval of data on an optical disc using alternate data modulation schemes to facilitate disc authentication efforts, including copy protection and forensic tracking.
Optical discs have become increasingly popular as efficient and cost-effective storage media for digitally stored data. A typical optical disc comprises a circular disc having a recording layer of light reflective material embedded in a refractive substrate. The recording layer is disposed along a plane substantially normal to an axis about which the disc is rotated and stores data in the form of localized pits and lands (also sometimes referred to as xe2x80x9cmarksxe2x80x9d and xe2x80x9cspacesxe2x80x9d) along a continuously extending spiral track.
The data are recovered from the disc through the use of a light source (such as a laser) which applies light of selected wavelength to the rotating disc, and a transducer which generates a readback signal indicative of the data in relation to the relative differences in reflectivity of the pits and lands. It is common to separate the relative elevations of the pits and lands by a distance equal to a quarter-wavelength of the applied light so as to facilitate a substantial change in the amount of light reflected by the pits as compared to the amount of light reflected by the lands.
One popular optical disc format is commonly referred to as compact disc, or CD, which has found widespread use in recent years in computer applications (such as CD-ROM) and in the music recording industry (audio CDs). A CD has an outer diameter of 120 millimeters (4.724 inches) and a data storage capacity of about 650 megabytes (MB). Another popular optical disc format is commonly referred to as digital versatile disc, or DVD. A DVD has the same form factor as a CD, but has a data storage capacity of about 4.7 gigabytes (GB) per layer. This increased storage capacity generally accommodates a feature-length video movie (DVD-video), or large amounts of other types of data (DVD-ROM, DVD-RAM, DVD-audio, etc.). Other optical disc configurations with different form factors and storage capacities have also been proposed and commercialized.
As will be recognized, the writing of data to an optical disc includes the encoding of each input group of data bits into a corresponding group of modulated bits. Such modulation is necessary to meet run-length requirements that specify how close and how far apart successive logical ones (pit/land transitions) can occur on the disc. If successive transitions are too close together, the detection circuitry may not be able to distinguish the individual transitions; if successive transitions are too far apart, the detection circuitry may lose frequency lock and thus be unable to recover the data from the disc.
Both CDs and DVDs utilize run-length requirements of at least two zeros and no more than ten zeros between successive ones. This results in pits and lands with symbol lengths that range from 3T to 11T, with T of determined period length.
CDs typically use what is referred to as 8/14 modulation (xe2x80x9cEFMxe2x80x9d) so that each 8 bits of input data are modulated into 14 bits of modulated data. For example, an 8-bit data pattern 00001010 (representing the number 10) can provide a corresponding 14-bit modulation pattern of 10010001000000. Since 8/14 modulation patterns (words) can start and/or end with a logical one, CDs additionally use three merge bits between successive modulation words to ensure the run-length rules are not violated at transitions between words. Hence, CD modulation is also sometimes referred to as 8/17 modulation.
DVDs typically use what is referred to as 8/16 modulation (xe2x80x9cEFM+xe2x80x9d) so that each 8 bits of input data are modulated into a corresponding 16-bit modulation pattern. For example, the 8-bit pattern 00001010 (representing the number 10) can result in a corresponding 16-bit modulation pattern of 0010010001000000. Unlike CDs, no merge bits are required between adjacent DVD modulation words.
Due to the worldwide consumer demand for the types of information available on optical discs (e.g., software, music, video, etc.), combined with the relative ease with which unauthorized copies of optical discs can be generated, suppliers of optical discs have attempted to incorporate schemes to authenticate the discs; that is, to determine whether a particular disc is an authorized copy. Such disc authentication can occur in the form of copy protection or forensic tracking efforts.
Generally, copy protection involves configuring the optical disc in such a manner that an authorized disc functions properly in a readback system, but an unauthorized copy does not. One common copy protection scheme used in CD-ROM discs is to write certain copy protection data at certain locations on the disc. When the CD-ROM is subsequently loaded into a host computer, a system processor polls these locations and verifies the contents before granting access to remaining portions of the disc.
Forensic tracking efforts generally entail storing certain xe2x80x9cmarkingxe2x80x9d or xe2x80x9ctrackingxe2x80x9d information on the disc. The forensic information usually does not prevent an unauthorized copy from functioning in the readback system, but based on the presence or absence of the information, a determination can be made whether a particular optical disc is in fact an authorized copy. Forensic information may include, for example, information relating to the ownership of the contents of the disc, when and where the mastering process occurred, etc.
Various ways to embed data in an optical disc for use in disc authentication efforts have been proposed in the prior art. A particular approach involves the creation of certain disruptions in the optical disc by violating the run length requirements of the modulation scheme used to record data to the optical disc. For example, in the case of the 8/14 CD and 8/16 DVD modulation schemes which only allow lengths of 3T-11T, embedded data can be incorporated having symbols that are less than 3T or greater than 11T in length.
There are several problems with this approach, however. The run-length requirements of a given modulation scheme are there to ensure the readback system can properly detect and decode the data. Hence, the optical tracking system may have trouble detecting symbol lengths that are too short and the recovery tracking oscillators may lose frequency lock if the symbols are too long. If the run-length violations are sufficiently severe, the violations can induce uncorrectable errors in the application data, compromising the integrity of the optical disc itself.
More importantly, such run-length violations are easily detectable using standard time interval analysis (TIA) test equipment, allowing unscrupulous parties to readily duplicate and defeat the copy protection or forensic information scheme altogether.
Because of these and other considerations, there remains a continued need in the art for improved ways to embed data on an optical disc for disc authentication purposes without interfering with the operability of the disc. It is to such improvements that the present invention is directed.
The present invention is directed to an apparatus and method for writing data to an optical disc, and for subsequently reading the data therefrom.
In accordance with preferred embodiments, a first modulation encoding scheme (MES1) is defined for the encoding of input data as data symbols having nominal symbol lengths over a first range of symbol lengths. The MES1 is generally related to the particular type of disc; for example, a CD will typically use 8/14 and a DVD will use 8/16.
A second modulation encoding scheme (MES2) different from the first modulation encoding scheme is also defined for the encoding of input data as data symbols having nominal symbol lengths over a second range of symbol lengths. The MES2 is selected to have the same (or to have more stringent) run-length rules than the MES1, so that each symbol length of the second range of symbol lengths from the MES2 appears in the first range of symbol lengths MES1. Moreover, the MES2 is configured to output different symbols for a given input word than the MES1.
The MES1 is used to encode and write primary data to the optical disc, with the primary data having an informational content used by a user of the optical disc. At selected times during the writing of the primary data, the MES2 is used to encode and write secondary data to the optical disc at a location adjacent a portion of the primary data. The secondary data have an informational content used to authenticate the optical disc as an authorized copy and include a leading synchronization pattern which, when detected, allows remaining portions of the secondary data to be decoded using the MES2.
Preferably, the data are subsequently read from the optical disc using a specially configured readback system having a primary decoder configured in accordance with the MES1 to decode the primary data, and a secondary decoder connected in parallel with the primary decoder configured in accordance with the MES2 to decode the secondary data. A readback modulation signal is transduced from the optical disc and concurrently transmitted to both the primary and secondary decoders. The primary decoder operates upon the readback modulation signal to output the primary data, while the secondary decoder searches the readback modulation signal for the leading synchronization pattern and, upon detection, outputs the secondary data. Preferably, the secondary decoder is further configured to detect and correct errors in the secondary data.
In this way, disc authentication data can be readily placed on the optical disc without interfering with the readback capabilities of the disc. Because the encoding of the secondary data does not violate the standard run-length rules for the disc (i.e., the MES1), no run-length violations will be detected.
These and various other features and advantages which characterize the present invention will be apparent from a reading of the following detailed description and a review of the associated drawings.

Optical disc authentication using alternate data modulation encoding schemes


Provided is an SiGe crystal having an improved performance index and excellent machinability as a material constituting a thermoelectric element, neither degradation in characteristics nor cracking occurring during use. Crystal grains forming the crystal are 5xc3x9710xe2x88x925 mm3 or more in size.

The present invention relates to a silicon germanium (SiGe) crystal preferably used as a thermoelectric element material and a thermoelectric element using the same.
When a P-type semiconductor material and a N-type semiconductor material are joined each other at two junctions and a temperature difference is given between the two junctions, there is generated thermoelectromotive force between them by the so-called Seebeck effect.
A thermoelectric element employing the above principle has no movable part and is simple in construction and hence with this element an energy direct conversion system which is high in reliability, long in lifetime and easy in maintenance may be quite within the bounds of possibility. Therefore, various kinds of thermoelectric element materials have conventionally produced and developed.
Among them, SiGe has been known as a typical thermoelectric element material of chemical stability and many proposals on improvements of its performance and production processes have been hitherto presented [for example, Japanese Patent Laid-open Publication No. 61-149453 (U.S. Pat. No. 4,711,971, European Patent No. 185499), Japanese Patent Laid-open Publication No. 8-56020, Japanese Patent No. 2623172].
The performance index Z which is an index of performance of the thermoelectric element is given by the following equation (1):
Z=xcex12"sgr"/Kxe2x80x83xe2x80x83(1)
[In the equation (1), xcex1 is the Seebeck coefficient, "sgr" the electric conductivity, and K the thermal conductivity.]
The performance indexes Z of various thrmoelectric element materials are shown in FIG. 7 in relation with the temperature. As is apparent from FIG. 7, in the case of an SiGe polycrystal obtained by a conventional production process, the performance index thereof is inferior to that of for example a tellurium based thermoelectric material such as Bi2Te2 or PbTe at a practical temperature ranging from 200xc2x0 C. especially to 600xc2x0 C., which is a weak point thereof in practical use.
Under these circumstances, in order to improve the performance index Z by raising the electric conductivity of the material with increase of concentrations of conduction electrons and holes thereof, there have been performed attempts wherein as dopants Group III elements such as B, Al and Ga are added into the P-type material, Group V elements such as P, As and Sb into the N-type material, and as disclosed in Japanese Patent Laid-open Publication Nos. 61-14953 and 8-56020, metals such as Pb, Sn, Fe, Ni and Cr, and silicides thereof into the material.
With these improvements, the performance index Z of SiGe has been improved, but there is a great demand for further improvements of the performance index for practical use.
There has been another problem, since an ingot of SiGe is produced by means of the casting method or the Bridgemann process in which components Si, Ge and additives such as dopants are mixed to form a mixture in respective predetermined amounts, and then molten to become a composition as homogeneous as possible, followed by cooling, or by means of powder sintering the mixture, the obtained ingot is collective concretion of crystal grains.
For the above reason, there have arisen the following obstacles {circumflex over (1)}xcx9c{circumflex over (3)} that hinders real practical use of SiGe as the thermoelectric material: {circumflex over (1)} As scattering of carriers at grain boundaries of the ingot cannot be avoided, the improvement of the electric conductivity thereof is impeded. {circumflex over (2)} As grain boundary segregation arises at a practical temperature of 200xc2x0 C. or higher, especially in the vicinity of a high temperature heat source of 500xc2x0 C. or higher, the characteristics thereof degrade in process of time. {circumflex over (3)} Local inhomogeneity of the composition in the ingot is inevitable, thereby characteristics being further degraded and cracking easily occurring not only in mechanical processing but during use.
Through a diligent research conducted with a view to the drawbacks of the polycrystalline SiGe obtained by the conventional production process, the present inventors have acquired an inventive idea that the drawbacks are solved and an SiGe thermoelectric element practically usable can be realized by increasing sizes of crystal grains forming an SiGe block, preferably of a single crystal. As a result of various actual investigations of the idea, the present inventors have succeeded in producing an SiGe crystal ingot composed of crystal grains of 5xc3x9710xe2x88x925 mm3 or more in size almost over all the range of x of SixGe1xe2x88x92x (0 less than x less than 1) by means of the Czochralski method.
It is an object of the present invention to provide an SiGe crystal material that realizes the improvement of the performance index as the thermoelectric element and is excellent in machinability, there arising neither degradation in the characteristics nor cracking during use.
To solve the above problem, an SixGe1xe2x88x92x (0 less than x less than 1) crystal of the present invention is characterized in that crystal grains forming said crystal are 5xc3x9710xe2x88x925 mm3 or more in size.
The SixGe1xe2x88x92x (0 less than x less than 1) crystal is preferably produced by means of a pulling method.
The SixGe1xe2x88x92x (0 less than x less than 1) crystal has preferably an absolute value of the Seebeck coefficient in the range of 100 to 700 xcexcV/K.
The SixGe1xe2x88x92x (0 less than x less than 1) crystal has preferably a value of a thermal conductivity in the range of 1 to 20 W/mxc2x7K.
The SixGe1xe2x88x92x (0 less than x less than 1) crystal has preferably a value of the electric conductivity in the range of 101 to 105 W/xcexa9xc2x7m.
The SixGe1xe2x88x92x (0 less than x less than 1) crystal has more preferably an absolute value of the Seebeck coefficient in the range of 100 to 700 xcexcV/K, a value of the thermal conductivity in the range of 1 to 20 W/mxc2x7K and a value of the electric conductivity in the range of 101 to 105 W/xcexa9xc2x7m.
The SixGe1xe2x88x92x (0 less than x less than 1) crystal has preferably a value of x in the range of 0.6 to 0.8.
A P-type thermoelectric material may be produced by adding an element selected from B, Al or Ga into the SixGe1xe2x88x92x (0 less than x less than 1) crystal.
An N-type thermoelectric material may be produced by adding an element selected from P, As or Sb into the SixGe1xe2x88x92x (0 less than x less than 1) crystal.
The SixGe1xe2x88x92x (0 less than x less than 1) crystal is preferably a single crystal.
A thermoelectric element of the present invention is characterized by using the SixGe1xe2x88x92x (0 less than x less than 1) crystal described above.
When sizes of crystal grains forming an SixGe1xe2x88x92x (0 less than x less than 1) crystal are increased, the mechanical strength of the crystal is improved and sustained highly especially at a high temperature at which a thermoelectric element is used, so that the crystal is mechanically stable under working environment of the element, and hence degradation of the element may be suppressed. These functions are more conveniently enhanced in the case where the crystal ingot is a single crystal.


The present invention relates to a system and method for locating the direction and distance to a RF signal source from an avalanche beacon to find an avalanche victim. The system and method includes a RF signal locator and a graphical display residing on the signal locator. The receiver graphical display provides the searcher with an initial way point reading that includes directional and distance data associated with the beacon RF signal source from the avalanche beacon. The directional and distance data is based upon the received RF signals. A processor within the locator receiver receives and measures RF signals emitted by the RF signal source. The locator advantageously provides continuous subsequent way point readings for the user, where the subsequent way point readings include directional and distance data associated with the RF signal source. The distance data provided by the subsequent way point readings is based upon a path loss slope of the received RF signals from the avalanche beacon.

1. Field of the Invention
The present invention relates to a direction and distance estimation system and method based upon characteristics of the Radio Frequency (RF) and the power path loss curve to locate victims.
2. Description of Related Art
Aircraft emergency locator systems such as ELTs (Emergency Locator Transmitters) and terrestrial location systems such as PLBs (Personal Locator Beacons) are well known in the existing art. Individuals lost at sea and fortunate enough to have emergency location identification devices such as an Emergency Position Indicating Radio Beacon (EPIRB), can send out RF signals with the hopes that their distress signals will be picked up by maritime stations or satellites, which can in turn, relay the information to the proper authorities.
Handheld or mobile location devices and systems can effectively locate the directional parameters associated with distress beacons; however, in order to obtain accurate distance readings, one must employ the use of satellites and global positioning systems (GPS). If a distress beacon emits a GPS signal to orbiting satellites, then a searcher may easily locate the distress beacon based upon the GPS reading. Many distress beacons currently being used are not equipped to transmit GPS readings and merely emit a RF signal for reception by a handheld, mobile, stationary or orbiting satellite receiver. As stated above, the RF receivers used to track and locate a RF signal from a distress beacon effectively locate the direction of the beacon, however reliable distance readings under this application are not possible. The lack of distance readings to the beacon can unnecessarily prolong or possibly imperil a search and rescue operation. If an individual is attempting to locate a person lost at sea, then initial movement of a search vessel is carefully monitored in order to prevent possibly running over the distressed victim. If the search vessel is a great distance from the distressed victim, then valuable time may be lost due to the necessity to move slowly during the searching process. If accurate distance readings were available, then the searching process could be shortened and therefore increase the likelihood of a successful rescue.
Directional and distance information may be equally important to search and rescue operations on land. Searchers may need to locate a distress beacon in dense woods or an urban metropolitan area. The beacon may be used by hikers, off road adventurers, skiers, campers and children. If the searcher is limited to directional data only, then even the effectiveness of a land search could be significantly diminished.
Avalanches are a great hazard to skiers, hikers and climbers and other people in mountain regions during winter. If a person is buried by snow, there is a very short period of time available to recover the person before he or she suffocates or dies of exposure due to the snow pack. The time factor in locating someone buried in an avalanche is a critical factor in the survival of the person buried. Electronic locating devices are known in the prior art to find victims of an avalanche that are buried under snow. Avalanche rescue devices manufactured by several companies transmit an RF signal on a frequency of 457 kHz. U.S. Pat. No. 6,031,482 issued to Lemaitre, et al., Feb. 29, 2000, discusses a method and system for sensing and locating a person, e.g. under an avalanche. Various types of electronic systems are discussed in this patent. U.S. Pat. No. 6,167,249 issued to Hereford, et al. discloses an avalanche victim locating transceiving apparatus that uses a plurality of different antennas that are arranged to provide directional and distance estimates to the victim along the lines of flux. None of the references exploit the RF characteristics of the field or power path loss curve to estimate a point to point direction and distance to an avalanche victim.
It would therefore be advantageous to provide a method and system for the location of a distress beacon that would provide the searcher with accurate distance and direction estimations. By providing a searcher with distance and directional estimations, the search time may be reduced significantly without endangering the distress victim. Although, the search and rescue operation has been discussed in association with sea and water rescue, distance estimations are also advantageous in regard to terrestrial search and rescue missions. It would also be advantageous if a handheld device facilitated the operation of the present system and method.

Direction and distance finder for locating distress signals


The jitter reduction circuit to reduce phase noise in a pulse train, comprises: —a resettable integrator (70) to integrate the pulse train, —a comparator (72) to compare the integrated pulse train with a reference level and to generate a modified pulse train with reduced phase noise, —a crossing time interval detector (94) configured to determine a discrete time interval during which the integrated pulse train crosses the reference level and to reset the integrator between two discrete time intervals determined consecutively.

The known jitter reduction circuit to reduce phase noise in a pulse train comprises:                a resettable integrator to integrate the pulse train,        a comparator to compare the integrated pulse train with a reference level and to generate a modified pulse train with reduced phase noise,
An example of such a jitter reduction circuit is described in WO 97/30516 in the name of UNDERHILL, Michael et al.
A known jitter reduction circuit continuously integrates the pulse train to obtain an analog sawtooth signal. The integration process is not perfect because of the use of capacitors and other electronic analog components. For example, if in one cycle, a capacitor is first charged from a voltage VA to a voltage VB with a current IA and then discharged from voltage VB to VA with a current −IA to generate one tooth of the sawtooth signal, an integration error appears. In fact, the time necessary to charge the capacitor from voltage VA to voltage VB is not exactly the same as the one necessary to discharge the same capacitor from voltage VB to voltage VA. The integration error is small for one cycle. However, in known jitter reduction circuits, the integration error is accumulated from one cycle to the next one so that the accumulated integration error grows more and more important. Thus, these jitter reduction circuits are unreliable.

Jitter reduction circuit and frequency synthesizer


The invention provides methods for efficient recombinant expression, refolding, and purification of Beta-site APP cleaving enzyme (BACE) polypeptides. In various aspects, the method includes the steps of expressing a recombinant construct in bacteria, dissolving inclusion bodies with a denaturant at high pH in the presence of a reducing agent, diluting the solubilized BACE polypeptide in an aqueous solution at a temperature of about 1° C. to 15° C., and incubating the diluted sample at a temperature of about 4° C. to 15° C. until the recombinant BACE polypeptide folds into an active enzyme.

Neuritic plaques containing primarily amyloid beta protein (Abeta) are one of the hallmarks of Alzheimer's Disease. Beta-site APP cleaving enzyme (BACE), known also as beta-secretase, Asp2, and Memapsin, has been identified as the enzyme responsible for processing amyloid precursor protein (APP) to produce the N-terminal portion of the Abeta peptide. This enzyme has been suggested as rate limiting in the production of the Abeta peptide. See, for example, Sinha et al., 1999, Nature 402:537-554, and published PCT applications WO 00/17369, WO 01/23533, and WO 98/22597. See also: Hussain, I. et al., 1999, Mol. Cell. Neurosci. 14:419-427; Vassar, R. et al., 1999, Science 286:735-741; Yan, R. et al., 2000, Nature 402:533-537; and Lin, X. et al., 2000, Proc. Natl. Acad. Sci. USA 97:1456-1460 (2000).
BACE is a therapeutic target for the development of inhibitory compounds for the treatment of Alzheimer's Disease. Rational drug design methods require supply of properly expressed, refolded, and active BACE in order to model and design appropriate new drugs. BACE in sufficient amounts has proven difficult to obtain.
BACE is a relatively large and structurally complex enzyme. The primary structure of BACE as it is synthesized in the endoplasmic reticulum is shown in FIG. 1 [SEQ ID NO:1]. The enzyme contains 501 amino acids, including a N-terminal signal (leader) sequence of about 21 amino acids (pre-sequence domain) followed by a pro-sequence domain consisting approximately of residues 22 to 45 (pro-sequence domain) that is proteolytically removed once the enzyme reaches its destination in the Golgi apparatus, to generate a mature enzyme.
Prosequence domains are commonly found in protease precursor polypeptides, where they generally function to prevent catalytic activity and assist in protein folding. The pro-sequence domain is typically cleaved from the protease precursor to generate a mature active protease. Previous work in a baculovirus expression system, expressing a BACE precursor having BACE pre-sequence and pro-sequence domains but truncated at the junction between the putative protease and transmembrane region, indicated that the pro-sequence domain facilitates proper folding of the BACE protease domain. See Shi, X-P. et al., Mar. 30, 2001, J. of Biol. Chem. 276(13):10366-10373.
BACE contains a transmembrane domain of about 27 amino acids that anchors the protein to the membrane. A short cytosolic C-terminal tail of 21 amino acids follows the transmembrane domain. Attachment to the membrane allows BACE to interact with and cleave APP, the first and prerequisite step in the generation of A-beta.
BACE isolated from human brain is heavily glycosylated. As expressed by a stably transfected 293T cell line, BACE is glycosylated at four asparagines: 132, 151, 202, and 333. Analysis of HEK 293 cells stably overexpressing BACE showed that the enzyme is phosphorylated at Ser477, and that phosphorylation regulates enzyme intracellular trafficking (Walter et. al., 2001, J. Biol. Chem. 276:14634-41). Three disulfide bonds suggested as critical for activity, are formed between the following pairs of cysteine residues: Cys195-Cys399, Cys257-Cys422, and Cys309-Cys359 (Haniu et. al., 2000, J. Biol. Chem. 275:21099-21106).
These structural features of the BACE polypeptide all appear to have specific functions relating to enzymatic activity. Enzymes expressed in insect and CHO cells are properly refolded and show activity. These proteins are glycosylated. For example, insect cells express glycosylated BACE, from the mannose-rich glycans available in the insect cells. Biantennary and triantennary oligosaccharides of the complex type provide glycosylation in the CHO-expressed BACE (Charlwood et. al., 2001 J. Biol. Chem. 276:16739-48). These glycosylated proteins have proven difficult to process, however, due to the heterogeneity conferred by differential glycosylation. BACE production in these cells generally requires expensive culture media and does not yield high amounts of protein.
These negative aspects of mammalian and insect cell expression do not apply to BACE proteins expressed in E. coli. Bacteria are easy to grow, produce high yields of protein, and the cost of culture media is low. However, E. coli do not provide for post-translational modifications of the protein.
Previous attempts to produce and isolate large quantities of active BACE from E. coli were initially unsuccessful. Although the cells grew well and expressed reasonable quantities of protein, refolding and isolating the enzyme using known published methods, including those described in Lin et. al. 2000, PNAS USA 97:1456-60 and Tang, WO 01/00663, failed to produce quantities of active BACE suitable for drug discovery methods.
Accordingly, a simple, efficient, and reliable method for expression of recombinant BACE in E. coli and for refolding and purification of sufficient quantities of BACE necessary for use in drug discovery methods is greatly needed.

This patent is subject to a terminal disclaimer.


A wavelength selector switch includes first and second refracting plates, an optical splitter, first and second optical systems, an optical coupler polarization controller, and second refracting plate. The first refracting plate refracts the second wavelength-multiplexed light beam. The optical splitter spatially splits into a plurality of wavelength components light beams. The first optical system changes the wavelength components into parallel light beams. The polarization controller selectively changes a polarization angle of each of the parallel light beams. The second optical system condenses the parallel light beams. The optical coupler multiplexes into a third wavelength-multiplexed light beam the parallel light beams condensed. The second refracting plate directs wavelength components of the third wavelength-multiplexed light beam to the first and second optical output ports depending on their polarization angles.

1) Field of the Invention
The present invention relates to a wavelength selector switch that selects wavelength-multiplexed light according to wavelengths and outputs the selected light to a desired port. The present invention, particularly, relates to the wavelength selector switch which allows all-optical cross-connect.
2) Description of the Related Art
Optical networks, which use wavelength-division multiplexing (WDM) communication, have been progressing rapidly to allow increasing traffic due to spread of the Internet and to make use of the existing optical fiber networks. The WDM communication, which is applied to a point-to-point network at present, has been researched for application to a ring network and a mesh network. Such a network allows optical processing in its network node with an optical add/drop multiplexer (OADM), which divides and combines light of desired wavelength, and an optical cross connect (OXC), which does not need opto-electric conversion. This optical processing can lead to control (e.g. setting and cancellation) of a dynamic path based on wavelength information. Progress of a photonic network technology which uses such optical technology fully is disclosed in, for example, U.S. Pat. No. 6,204,946.
The OADM or OXC includes a wavelength selector switch. FIG. 34 is a schematic diagram of the wavelength selector switch. As shown in FIG. 34, optical transmission paths of two system, i.e. a first optical transmission path 111a is operated as a main line of an optical fiber transmission linear path and a second optical transmission path 111b is operated as a branched line.
A wavelength selector switch 110 is disposed between the first optical transmission path 111a and the second optical transmission path 111b such that the wavelength selector switch 110 connects nodes of the first optical transmission 111a and the second optical transmission path 111b. The wavelength selector switch 110 includes two optical input ports In and Add and two optical output ports Pass and Drop. Concretely, the ports are named as an input port In, a combining port Add, a passing optical output port Pass, and a dividing optical output port Drop respectively.
Light that is input via the optical input ports In and Add, is a WDM signal that includes a plurality of wavelength components. The typical wavelength space is 100 GHz (0.8 nm) and a number of wavelengths is from a few wavelengths to a few tens of wavelengths (for example 32 wavelengths; in this case, for λn, n=32). A circulator 112a is combined with (inserted into) the node of the first optical transmission path 111a and a circulator 112b is combined with (inserted into) the node of the second optical transmission path 111b. The circulators 112a and 112b have a function of outputting light that is input to an optical input port C1 from an optical input-output port C2 and a function of outputting light that is input to the optical input-output port C2 from an optical output port C3 respectively.
An optical switch module 114 is disposed between optical input-output ports C2 of the circulators 112a and 112b. The optical switch module 114 includes optical systems 117, a diffraction grating 118, and a micro mirror array 121 formed by micro electromechanical systems (MEMS). The optical systems 117 (not shown in detail in the diagram) includes lenses like a collimating lens and a collective lens (Refer to U.S. Pat. No. 6,204,946).
According to such structure, light that is output from the optical input-output port C2 of the circulator 112a is incident on a grating surface of the diffraction grating 118 via the optical system 117. The diffraction grating 118 is an element that imparts a different diffraction angle to a different wavelength component that is incident at a predetermined angle. Therefore, a WDM signal that is reflected from the diffraction grating 118 is separated spatially for every component of wavelength λ and is collected on the micro mirror array 121.
By controlling a micro mirror 122 for different wavelengths that are provided in the micro mirror array 121, the light of wavelengths from λ1 to λn that is collected on the micro mirror array 121 is either reflected through the same optical path as that of the incident light or is reflected through a different optical path.
The micro mirror array 121 is a mirror that is manufactured by using a micro machine technology. The micro machine technology is disclosed in pages 94 to 103 of February 2002 issue of a Journal of IEICE (The Institute of Electronics, Information & Communication engineers) and "Micro mechanical optical device" on pages 1274 to 1284 of no. 11, 69th volume of JAPANESE JOURNAL OF APPLIED PHYSICS (published by The Japan Society of Applied Physics). The micro mirror 122 as shown in the diagram is an arrangement of a plurality of micro mirrors 122a to 122n that are arranged at a distance of tens of μm from each other. The number of micro mirrors 122n is same as the number n in which wavelengths λ is split (separated) and one micro mirror corresponds to one wavelength component. Light of wavelengths from λ1 to λn that is separated by the diffraction grating 118 is incident on the micro mirror 122 (122a to 122n) in a position corresponding to that particular wavelength.
FIG. 35 is a side view of a micro mirror arrangement that is provided in the micro mirror array. FIG. 36 is an illustration of an operation of the micro mirror. The micro mirror 122 includes a substrate 123, a support 124 that protrudes from the substrate 123, and a reflector 125 that is supported at a center by the support 124. Surface 125a of the reflector 125 is a total reflecting surface from which light A and B are reflected totally. The substrate 123 includes a pair of electrodes 126a and 126b in the form of a flat plate facing the reflector 125 with the support 124 sandwiched between the electrodes 126a, 126b and the reflector 125. An electrode 127 in the form of a flat plate is provided an overall rear surface of the reflector 125 facing the electrodes 126a and 126b.
When voltage is applied to the electrode 126a, static electricity is generated between the electrodes 126a and 127 that are facing each other. Due to the static electricity, the electrode 127 is attracted towards the electrode 126a and the reflector 125 is inclined to one side with the support 124 as a center, as shown in FIG. 35.
With the electrode 127 attracted towards the electrode 126a, light incident on the reflector 125 is allowed to be reflected in a direction same as that of the light beam A. Concretely, the surface 125a of the reflector 125 is adjusted such that the surface 125a is orthogonal (at right angles) to direction of light A that is incident. Due to this, the light that is input from the optical input port In can be returned in the same optical path and can be output from the optical output port Pass.
On the other, when voltage is applied to the electrode 126b, static electricity is generated between the electrodes 126b and 127 that are facing each other. Due to the static electricity, the electrode 127 is attracted towards the electrode 126b and the reflector 125 is inclined to one side with the support 124 as the center as shown in FIG. 18.
With the electrode 127 attracted towards the electrode 126b, light beams A and B that are incident on the reflector 125 are reflected to follow different optical paths. Concretely, the reflector 125 is adjusted such that the angle of the surface of the reflector 125 is at predetermined angles (θ) with the light beams A and B that are incident. This enables to output the light beam A that is input from the optical input port In from the optical output port Drop by switching to an optical path of the other light beam B. Similarly, the light beam B that is input from the optical input port Add can be output from the optical output port Pass by switching to an optical path of the other light beam A.
Thus, the light input to the optical input ports In and Add can be selected according to wavelengths λ1 to λn and can be output from the optical output ports Pass and Drop upon switching. For example, as shown in FIG. 34, let the light from the (optical input port) In of the first optical transmission path 111a has wavelengths λ1, λ2, and λ3 and the light from the (optical input port) Add of the second optical transmission path 111b has wavelengths λa, λb, and λc (where wavelengths λ1 =λa, λ2=λb, and λ3=λc). A certain wavelength can be selected and be made to switch to a different optical path by changing the angle of the micro mirror 122. Thus, the wavelengths λa, λ2, and λc can be output from the optical output port Pass of the first optical transmission path and the wavelengths λ1, λb, and λ3 can be output from the optical output port Drop of the second optical transmission path.
Thus, by using the micro mirror array 121, the direction of reflection of the light beams A and B of wavelengths λ1 to λn that are incident on the micro mirror array 121 can be switched for each frequency component. Thus, it is possible to use the second optical transmission path (branched line) as a back-up circuit of the first optical transmission path (main line) and to perform operations like transmitting by switching a specific wavelength λ only, for which the transmission was hindered in one of the optical transmission paths, to the other optical transmission path.
However, in the wavelength selector switch 110 that employs the micro mirror array, the all-optical cross-connect could not be achieved. The micro mirror 122 that is used in the micro mirror array 121 can switch the light from the second optical input ports In and Add and the second optical output ports Pass and Drop mutually when the angle is changed as shown in FIG. 36. Whereas, in a situation that is illustrated in FIG. 35, light incident from one of the optical input ports In of the first optical transmission path cannot be returned to the optical output port Pass.
In other words, in a situation that is illustrated in FIG. 35, it is not possible to switch an overall optical path of the other optical input port Add of the second optical transmission path 111b. In this situation, even if the light is incident from the optical input port Add, the micro mirror 122 is inclined at an angle such that the incident light cannot be reflected to any of the ports. Thus, the conventional wavelength selector switch 110, due to the arrangement in the micro mirror array 121 has not been able to achieve the all-optical cross-connect in which the light from the two optical input ports is always switched to any of the two optical output ports. An all-optical cross-connect at present implies a possibility of switching the light to a desired port for each wavelength by using a structure of 2×2 ports (i.e. two input ports and two output ports).
The voltage is to be applied continuously to either the electrode 126a or the electrode 126b to maintain the status in which the angle of the micro mirror 122 in the micro mirror array 121 is changed. If the voltage is stopped, the switching of the optical path that is maintained cannot be continued. Apart from this, an optical axis of the light incident on and output from the micro mirror 122 from the plurality of micro mirrors in the micro mirror 122 has to be adjusted which is a tedious job. Moreover, the components in the arrangement being the micro members, the component cost goes high and the durability of the structure that changes the angle of the micro mirrors 122 becomes an issue.


A method comprises depositing a dielectric film layer, a hard mask layer, and a patterned photo resist layer on a substrate. The method further includes selectively etching the dielectric film layer to form sub-lithographic features by reactive ion etch processing and depositing a barrier metal layer and a copper layer. The method further includes etching the barrier metal layer and hard mask layer by gas cluster ion beam (GCIB) processing.

Surfaces of microelectronic materials such as semiconductors, dielectrics, and metals (often as thin films on a substrate) are generally planarized after their fabrication. The close proximity of microelectronic components, either as multiple layers or as interacting and interconnected subcomponents, requires a high degree of uniformity of the surface. Advances in semiconductor technology have seen the advent of very large scale integration (VLSI) and ultra large scale integration (ULSI) circuits, resulting in the integration of very many more devices in smaller areas on a semiconductor substrate.
The greater device densities require greater degrees of planarity to permit the higher resolution lithographic processes required to form the greater number of devices having smaller features as incorporated in current designs. That is, as successive generations of improvements in semiconductor fabrication are implemented, the tolerance for scratches, erosion, contamination, or other imperfections in the smoothed surface becomes smaller.
One such method of planarization is by chemical mechanical polishing (CMP). CMP, though, is limited because the physical polish often generates scratches, erosion, or other surface defects on the wafer surface. Additionally, the polish rate depends upon the pattern density factor; thus the longer the polish, the worse the uniformity. This non-uniformity of the surface is not within the acceptable tolerances for processing the very thin wire levels of emerging fabrication methods. Also, for fatwire levels, a thick CMP hard mask is often required in the film stack to be sure that some hard mask remains after CMP, if desired.
FIG. 1 shows a graph of the line resistance distribution of multiple chips on twelve wafers—each chip has nested lines with widths of 2.5 μm, 6 μm, 15 μm, and 25 μm, and having 50% pattern density—formed using a conventional CMP process. Along the x-axis are the wafer IDs, and along the y-axis is the line resistance in Ohms. As will be appreciated by one skilled in the art, it is desirable to have uniformity of resistance across the wafer in order to optimize performance. The four different lines on the graph show the resistance varies considerably across each wafer.
Thus, it is desirable to achieve a more planar and smoothed surface, with extremely uniform line resistance across the wafer, even when the surface includes complex structures.

Integrated circuit fabrication process using gas cluster ion beam etching

International Business Machines Corporation


An illuminative sucker includes a decorative back portion formed on a back portion of a sucker cup portion adhered on a flat surface, a lamp selected from a light-emitting diode and an incandescent bulb fixed on a lamp socket secured to the back portion of the sucker cup portion for illuminating the decorative back portion for decorative display or warning purposes. A plurality of the illuminative suckers may be assembled to be a string adhered on a flat surface for wide-area decorative, display or warning purposes.

A conventional Christmas-light string includes a plurality of Christmas lights or bulbs connected to a power source by a lengthy electrical cord which can be hung on a Christmas tree or any structure. However, it can not be adhered on a slippery surface such as a window glass to thereby limit its decorative uses and applications.
If it is intended to decorate a glass window with such a light (lamp) string, an additional stand, frame or even a display device should be further provided adjacent to the window for hanging the string of decorative lights (lamps), causing a very inconvenient installation and cost consuming job therefore.

Illuminative sucker & decorative string thereof

c/o Hung Hsing Patent Service Center, P.O. Box 55-1670


A transistor is provided that includes a silicon layer with a source region and a drain region, a gate stack disposed on the silicon layer between the source region and the drain region, an L shaped gate encapsulation layer disposed on sidewalls of the gate stack, and a spacer disposed above the horizontal portion of the gate encapsulation layer and adjacent to the vertical portion of the gate encapsulation layer. The gate stack has a first layer of high dielectric constant material, a second layer comprising a metal or metal alloy, and a third layer comprising silicon or polysilicon. The gate encapsulation layer has a vertical portion covering the sidewalls of the first, second, and third layers of the gate stack and a horizontal portion covering a portion of the silicon layer that is adjacent to the gate stack.

High dielectric constant (high-K) transistors in conjunction with metal gates, or "MHK transistors", are undergoing active development in the industry. In an MHK transistor, any extrinsic oxygen that enters the formed high-k gate layer during subsequent processing changes the electrical properties of the MHK transistor. One of the more deleterious impacts of extrinsic oxygen is the lower K interfacial oxide (SiOx) regrowth underneath the high-K layer. It is critical to prevent such dielectric regrowth in order to achieve the desired dielectric thickness and maintain good short channel control. A conventional MHK transistor, such as the one disclosed in U.S. Patent Application Publication No. 2004/033678, uses an I-shaped gate encapsulation layer to protect the high-k gate layer from such dielectric regrowth. While this protects the high-k gate layer, one observed problem with such a transistor is that an I-shaped gate encapsulation layer often leads to the high-k/metal gate layer being exposed, so as to leave it open to attack during subsequent wet etching with the possibility of extrinsic oxygen ingress.
When the metal high-k gate stack is not perfectly vertical but instead has a sloped profile, the I-shaped gate encapsulation layer does not sufficiently protect the metal layer of the gate stack. This leaves the metal gate layer exposed and open to oxygen ingress and attack during subsequent wet etches In particular, the edge of the metal gate layer is exposed so that metal is etched out. As a result of the gate being undercut, the electrical properties of the metal high-k transistor are changed. Further, in many cases the gate is undercut to such an extent that the gate stack lifts off and is then re-deposited elsewhere on the integrated circuit wafer. Thus, the use of an I-shaped gate encapsulation layer to protect the gate stack results in poor yield and a process that is not robust.

High-k/metal gate transistor with L-shaped gate encapsulation layer


A hose coupling using at least one reinforcing ring to reinforce a hose coupling during a crimping process, the hose coupling having an inner sleeve, an outer sleeve coaxial with the inner sleeve, and a hose coaxially interposed therebetween. During the crimping process a crimping force is applied directly to the outer sleeve to form at least one depression that results in an area of peak crimp force on the inner sleeve, the depression helping to seal and lock the hose between the inner and outer sleeves. The reinforcing ring is positioned within the inner sleeve and concentric with the area of peak crimp force on the inner sleeve. Consequently, the reinforcing ring prevents the inner sleeve from deforming under the crimping force, thereby ensuring the integrity and long-term durability of the hose coupling. The reinforcing ring preferably has an inside diameter equal to or greater than an inside diameter of the inner sleeve and is disposed within at least one groove located within the inner sleeve to permit unrestricted fluid flow through the hose coupling.

1. Field of the Invention
The present invention relates generally to conduit couplings. More particularly, the present invention relates to a compact reinforcement to be used in a crimped coupling for high-pressure hose connections such as in an automotive air-conditioning system.
2. Description of the Prior Art
It is generally known in the art relating to flexible conduit couplings to utilize a coupling member having a collar or concentric circular sleeves. The collar, or outer sleeve, is crimped over a hose circumscribing an inner sleeve in order to engage the hose to the coupling member and create a sealed coupling. Generally, to resist the crimping forces, the inner sleeve is made of heavy gauge steel. Unfortunately, heavy gauge steel adds unwanted cost and weight to the coupling assembly.
O-rings and split rings have been used in couplings for sealing and engaging a hose. For example U.S. Pat. Nos. 5,044,671 and 5,096,231 to Chisnell et al. disclose a hose fitting assembly having a resilient sealing member, such as an O-ring or nylon bushing, on the outer periphery of the inner sleeve that sealingly engages the hose to create a sealed coupling. While the sealing members provide a seal to prevent leaks, they do not add any structural benefit to the fitting, nor do they protect the inner coupling member from forces applied to crimp the coupling to the hose.
U.S. Pat. No. 2,250,286 to White discloses a coupling having two concentric circular sleeves. The outer sleeve has a protuberance that contains a split ring that engages the hose with the coupling member when the protuberance is depressed. The depression of the protuberance presses the split ring against the material of the hose and thereby holds the hose firmly between the two sleeves of the coupling. The hose coupling is designed to compress and deform in order to securely engage the hose between the split ring and the inner sleeve of the coupling. Therefore, coupling and use of the split ring to enhance sealing does not in any way prevent the inner sleeve of the coupling from deformation in case of an excessive crimping force.
U.S. Pat. No. 863,745 to Nelson et al. discloses a metal strengthening ring concentrically located between a rubber inner portion and fabric outer portion of a hose. The strengthening ring strengthens an enlarged head portion of the fabric outer portion of the hose, and the coupling is not necessarily crimped at the point where the strengthening ring is located. The placement of the ring prevents expansion of the inner rubber portion of the hose over the strengthening ring and compression of the rubber hose between the ring and the coupling sleeve, that causes damage to the hose and speeds deterioration and failure of the hose and coupling connection. Therefore, the strengthening ring may reinforce the hose, but does not necessarily protect the inner sleeve of the coupling from excessive crimping forces.
More recently, there have been attempts to produce couplings from lightweight materials such as aluminum. However, because of the crimping force necessary to secure the hose to the coupling, reinforcement is required to prevent the weaker aluminum coupling from deforming. Accordingly, U.S. Pat. No. 5,387,016 to Joseph et al. discloses such a tubular coupling fabricated from aluminum that includes a tubular liner having a predetermined length that is press-fit into the tubular connector body. The tubular liner provides structural rigidity and strength to the aluminum connector thereby protecting the coupling from deforming under the crimping force required to connect the tubular connector body to the end of the rubber hose.
Furthermore, Joseph et al. discloses that the tubular liner is formed from a different material than the material of the coupling body to increase the structural rigidity of the body. Therefore, the benefit of using lightweight aluminum for the connector body is countered by the burden of the added weight of the tubular liner. In other words, while the tubular liner of Joseph et al. may add strength, it also adds significantly more weight and cost.
Another problem with the relatively long tubular insert of Joseph et al. is one of beam deflection. Under radial compression, the relatively long tubular liner is weaker and more prone to deflection than a more discrete element of the same cross section would be. That is, when the crimping force is applied to the coupling, the relatively long tubular liner will have a tendency to compress relatively easily because of cumulative deflection along the length of the tubular liner. A more discrete element would undergo relatively minute beam deflection.
Additionally, in an automotive air-conditioning system, the flow of fluid, such as refrigerant fluid, should not be disrupted or it may adversely affect the operation of the air-conditioning system. Accordingly, a disadvantage of the tubular liner disclosed by Joseph et al. is that the reduced inner diameter of the coupling over the entire length of the tubular liner results in a significantly restricted flow of fluid through the coupling.
Further, in a vehicle's air-conditioning system, hose couplings are exposed to a harsh environment where the hose couplings are damaged due to heat and vibrations generated by the vehicle's engine. The harsh engine environment coupled with increased pressure on the hose couplings at the deformed crimped connections has been known to cause prior art couplings to fail prematurely. A discrete reinforcement member in the coupling can provide reinforcement that helps the coupling to overcome the above mentioned shortcomings of the prior art.
Finally, prior art crimped couplings for steel and aluminum couplings have been tested by the applicant of the present invention. Throughout a variety of tests and observation of failed components, it has been concluded that when the crimped connection fails, it fails repeatedly in the same location, independent of whether a steel coupling, an aluminum coupling, or an aluminum coupling with a tubular liner is used. Accordingly, there continues to be a need for a lower cost, lighter weight reinforcement for a hose coupling that will provide support necessary to withstand crimping forces on the tubular body. Finally, the solution must be cost effective, lighter in weight, and not restrict fluid flow through the hose coupling.


A system and method for estimating the range between two devices performs two or more ranging estimates with subsequent estimates performed using a clock that is offset in phase with respect to a prior estimate. The subsequent estimate allows estimate uncertainties due to a finite clock resolution to be reduced and can yield a range estimate with a higher degree of confidence. In one embodiment, these additional ranging estimates are performed at n/N (for n=1, . . . N−1, with N>1 and a positive integer) clock-period offset introduced in the device. The clock-period offset can be implemented using a number of approaches, and the effect of clock drift in the devices due to relative clock-frequency offset can also be determined. To eliminate the bias due to clock-frequency offset, a system and method to estimate the clock-frequency offset is also presented.

With the many continued advancements in communications technology, more and more devices are being introduced in both the consumer and commercial sectors with advanced communications capabilities. Additionally, advances in processing power and low-power consumption technologies, as well as advances in data coding techniques have led to the proliferation of wired and wireless communications capabilities on a more widespread basis.
For example, wired and wireless communication networks are now commonplace in many home and office environments. Such networks allow various heretofore independent devices to share data and other information to enhance productivity or simply to improve their convenience to the user. One such communication network that is gaining widespread popularity is an exemplary implementation of a wireless network such as that specified by the WiMedia-MBOA (Multiband OFDM Alliance). Other exemplary networks include the Bluetooth® communications network and various IEEE standards-based networks such as 802.11 and 802.16 communications networks.
Computing the distance of a target wireless device from a reference wireless device is called ranging. Ranging can be performed by measuring the received signal strength (RSS) or the time of arrival (time-of-arrival) of the signal propagated between the target and reference node. The ranging accuracy using the received signal strength depends on the accurate modeling of path-loss and the propagation channel environment. On the other hand, the ranging accuracy using time-of-arrival typically depends on the estimation accuracy of time of arrival, because electromagnetic waves propagate at approximately the speed of light and thus a small error (in the nanosecond scale) in time translates to larger error in distance. The estimation accuracy of time of arrival depends on the available signal bandwidth, and the accuracy and resolution of the sampling clock frequency. Therefore, ultra wideband (UWB) technology that occupies greater than 500 MHz bandwidth is suitable for ranging and provides centimeter-level accuracy. The proposed effort for IEEE 802.15.3a and WiMedia standardizes UWB technology to provide high-rate (>53.3 MB/s) wireless connectivity in wireless personal network (WPAN) and WiMedia has proposed two-way ranging (TWR) as an additional feature for UWB systems. Also, the specifications of IEEE 802.15.4a for low-rate (<250 KB/s) WPAN makes ranging mandatory.
Ranging using multiple reference devices can enable positioning. Computing the 2D/3D position of a target wireless device relative to a coordinate system commonly known to a set of reference devices is called positioning. One common positioning system is the Global Positioning System, or GPS. Geodesic positioning obtained by a GPS receiver requires synchronous signal from at least four satellites. Although, the coverage of GPS positioning is broad, it requires line-of-sight connectivity from the satellites that may not exist in certain geographic locations. Indoor coverage may suffer as well, such as in office building, shopping mall, warehouse, auditorium, indoor stadium, parking structure. Furthermore, GPS receivers are costly and provide only meter-level accuracy.
Another ranging technique is the local positioning systems (LPS). Local positioning systems can provide indoor positioning using an ad-hoc wireless sensor network. To provide different emerging applications of location awareness, the location of such sensors has to be accurate and automatically configurable. A host of applications can be envisioned using the LPS. For example: (i) LPS for public safety—placing a localizer along a trail to mark the route, locating fire fighters in a burning building, locating children lost in the mall or park, etc.; (ii) LPS for smart home applications—automatic door opening when the resident is in the vicinity, activating certain appliances or devices depending on resident location, timing adjustment of light, temperature and sound level per individual profile, finding personal item such as pets, keys, purse, luggage; (iii) LPS in inventory control—localizers for real-time inventory, differentiating the contents of one container from the others; locating a book in the library, a document file in a law office; (iv) LPS for health care—hospital staff, patients and assets tracking, simplified record keeping and workflow, raising an alert if a staff member had not check a particular patient, visitor tracking for security, automatic pop-up of patient record on a tablet PC for a doctor's visit; and (iv) LPS for intelligent vehicle highway system—placing localizers along the side of a road to use as guide posts, placing localizers in vehicles to provide local intelligence for safety and providing centimeter level accuracy as opposed to meter level accuracy using GPS. Thus, ubiquitous use of position awareness implies local positioning systems which are expected to be low-cost, low-power, small-size and have scaleable accuracy.
Two-way ranging between a pair of devices has been used in various applications, including wireless networks. In general, ranging accuracy of the time-of-flight-based method depends on the signal bandwidth used in the transactions. However, assuming an operating bandwidth of the receiver to be higher than the signal bandwidth, the rate of the sampling clock affects the timing accuracy of ranging transactions—the higher the rate of the sampling clock, the higher the ranging accuracy. This is due to the fact that sampling with a higher clock frequency results in a more accurate timing resolution. However, due to the difficulty of accurately synchronizing all devices in certain applications, two-way ranging accuracies can be somewhat diminished. For example, if the respective clocks of the devices participating in the measurement have relative offset between them, a certain amount of error will be introduced in the measurement.
One way to improve the accuracy is to increase the frequency of the clock. At higher frequencies, the clock periods are shorter and thus the maximum offset is smaller. The higher clock frequency also makes time resolutions finer, reducing uncertainties related to time quantization noise. For example, using 528 MHz sampling clock rate gives the finite ranging resolution of 56.8 cm. Typically, the overall offset is statistically smaller as well. However, it is not always possible, practical or desirable to increase the rate of the sampling clock. Higher clock frequency requires higher complexity and higher power consumption in the device.


A cross flow filtration apparatus for nanofiltration or reverse osmosis has pressure vessels with a plurality of filter cartridges in each vessel. A feed port is provided at an intermediate position on the side of the vessel, and two permeate flows or branches exit opposite ends of the vessel, and the first branch has a characteristically high “upstream” flux and quality, while the second is of lesser flux and/or quality. The system provides a high degree of moduarity, enhancing flux or yield at a reduced driving pressure or overall pressure drop. Centered or off-center port, and a stop or valve in the permeate stream may apportion flows between the two outlets. Staged systems may employ a first stage bypass to achieve a target quality with increased yield. A flow divider or adaptor permits the cartridges to fit and seal in the vessel and an installation tool or sleeve may facilitate installation or replacement of cartridges having a directional perimeter seal. A tool permits modules to be bi-directional installed in the pressure vessel. Other embodiments involve adapting a conventional vessel designed for end-to-end feed flow utilizing a restrictor, obstruction or valve inside the filter cartridge to bifurcate or otherwise split or apportion the permeate. RO elements may be modified to movably position an obstruction or valve along a string of the elements and vary the take-off to two or more permeate outlets, or to provide pressure relief valves that present different pressure conditions for different elements of a string. A pressure vessel may have an intermediate inlet, with symmetric or asymmetric branching of permeate flow to opposed ends of the vessel, enhancing permeate flux, permeate quality and/or energy efficiency.

The invention pertains to filtration apparatus for treating fluids, and particularly relates to high volume or high flow treatment plants, such as public drinking water, agricultural water or industrial water treatment plants.
In the modern world, water treatment plants are specified by clients or required by government regulations to have certain maximum concentrations of various chemical species. The equipment and methods used to treat feed waters to achieve specified product water quality may or may not be set forth in detail. Final equipment design and method of operation are usually determined by the system suppliers, e.g., specialized water treatment engineering firms and equipment manufacturers. In many instances a water user accepts a bid for specified product water quality and quantity from a water supplier who is to own and operate the water treatment plant, and the user does not set any specifications on the plant or on the selection of equipment/design. This last arrangement often provides the user with the lowest possible water supply cost. Large treatment plants often rely on a filtration process employing major plumbed-in units, such as banks of modular pressure vessels containing RO or other filter elements, for at least one stage of treatment.
These filtration systems, such as nanofiltration (NF) or reverse osmosis (RO) water treatment apparatus, are typically implemented in high-flow treatment applications as cross-flow systems wherein a string or series of filter cartridges are arranged in a lesser number of high pressure fluid vessels, and pumps direct the feed flow through the pressure vessels such that the flow proceeds across the surface of membranes in the cartridges, while permeate passes through the membranes and out via a collection manifold.
Modern filtration pressure vessels may fit up to about eight spiral wound or other membrane filter elements in hydraulic series. These pressure vessels commonly have a single feed inlet, a single reject stream outlet for residual flow of the retentate, and permeate outlets at one or both ends of the vessel. Large water treatment plants often use modular banks of such pressure vessels in order to save money on the cost of valves and piping. High pressure piping and valves required for feeding pressure vessels are relatively more expensive than the lower-pressure conduits employed for the permeate and reject streams, and provision of multi-element pressure vessels reduces the overall number of required pipe connections. The pressure vessels are typically slightly larger in diameter than the filter elements (e.g., RO elements), and as feed water passes each RO element a portion of the water permeates through RO membranes and is collected in the permeate tubes and manifolds. The flow volume and flow velocity of the feed stream progressively fall with downstream position, and the concentration of chemical species in the remaining feed water progressively increases after passage along each element due to such permeation loss. Correspondingly, the amount and quality of permeate that passes through each downstream filter element drops. Thus, a multi-element pressure vessel with n elements produces permeate at a rate that is typically less than n times the output of a single element, and the permeate is also of an intermediate quality which is lower than that of a single element.
The filter "transfer function" of the individual units is determined by membrane type, and varies locally with the driving pressure, ionic content of the feed, temperature, pH and other factors. The general mechanisms and limitations of these processes are best illustrated in the context of reverse osmosis (RO) systems operating to demineralize an aqueous feed, and the discussion of art and description of the invention below shall, for clarity and consistency, refer to RO units, although those skilled in the art will understand that the improvement of this invention may be implemented with corresponding or analogous structure for other filtration devices, and all of these corresponding or analogous structure embodiments are considered to be within the scope of this invention.
Filtration or treatment units of this type remove different undesired species to varying degrees, and membranes may be specialized in different ways to specifically address typical seawater, brackish water or fresh water loading and treatment requirements. A large number of publications deal with the removal of poorly rejected chemical species in liquids treated by RO. U.S. Pat. No. 4,574,049 (as Re-examined) teaches the use of a double pass RO system where sufficient caustic is added to the permeate of the first pass RO upstream of the second pass RO to improve rejection of carbon dioxide by chemical conversion, thus reducing passage of carbon dioxide into the product (as well as ionizing certain other species, if present). U.S. Pat. No. 5,250,185 of Tao, et al., teaches the use of high pH feeds to RO units to improve removal (rejection) of boron. U.S. Pat. No. 5,925,255 teaches increasing the pH of a suitably pre-treated RO feed to improve rejection of poorly ionized species such as boron, silica, and some organics and to reduce the fouling of certain RO membranes. U.S. Pat. No. 6,267,891 teaches the use of ion exchange pretreatment, degassing, and pH control to maximize resistivity of a high purity water produced by a double pass RO system. Many other systems involve ordered regimens of pH change, degassing, scrubbing and filtration and other operations to permit the efficient removal of multiple problematic component pairs of constituents. All of these processes require extensive pretreatment equipment, and most also involve substantial chemical usage on an ongoing basis.
A bulk cross flow filtration process, such as reverse osmosis, is a pressure-driven process that involves filtration by passing the fluid through a filtration medium, such as a filter membrane, positioned across an overall input/output fluid path while the face of the filter membrane is washed by the feed flow. A portion of the fluid permeates through the membrane and is collected as a permeate or filtrate stream, while the remainder of the feed flow traveling along the face of the membrane exits the apparatus as a reject, brine or concentrate stream. Certain impurities, such as suspended matter (if not already removed by pretreatment), ions, and molecules above a certain size are rejected by the membrane. These become concentrated in the reject stream, while other components in the fluid may pass through the membrane into the filtrate. The filtration medium may be contained within a bag, cartridge or cylindrical pressure vessel, and typically is a porous, semi-permeable or selectively permeable membrane that is mounted in a generally cylindrical cartridge. Cartridge elements are typically either of a construction that employs a spiral wound sheet filter membrane or alternatively a bundle of hollow fiber filter membrane elements. Such cartridges may be dimensioned to fit within a cylindrical housing or pressure vessel and to communicate with suitable inlet and outlet manifolds and/or ports on adjacent cartridges and/or the pressure vessel. The pressure vessel permits the process to operate at a controlled pressure above the threshold driving force needed for permeation through the fiber or membrane filter. Typically, for processes such as ultrafiltration or reverse osmosis, this pressure is in the range of two to eighty atmospheres, and the pressure vessel is a cylindrical vessel having a length that may accommodate four or more filter cartridges. In the prior art, the high pressure filtration cartridges, such as reverse osmosis cartridges, are typically arranged in a string or series with each other in the flow stream. The cartridges are generally all of the same type or manufacture, and are inserted seriatim from one end of the vessel. Short interconnecting fittings, e.g., short press-fit couplers, may be added between the permeate pipes of successive cartridges in the series. One or more peripheral seals may extend around the outside of each cartridge to generally force the feed water to pass over the membranes of each cartridge in sequence rather than flowing directly around the outside of the cartridge to the downstream elements.
In devices of this type, feed fluid commonly enters at one end of the pressure vessel, at a high rate of flow, and travels along the length of the vessel contacting one side (e.g., either the inside or the outside) of the filter membrane mounted in each filter cartridge. The portion of the feed fluid which does not permeate through the filter membrane exits the apparatus at the opposite end of the pressure vessel as a concentrated retentate or reject stream. Throughout the length of the vessel, fluid is driven through the membranes of the cartridges (e.g., against the osmotic gradient in the case of RO membranes), and the fluid that crosses the filter medium is collected by a suitable manifold structure in each cartridge and passed to one or more outlets of the pressure vessel as a permeate or filtered output stream. Typically the vessel is provided with suitable pipe fittings, which may be incorporated in end caps or other structures, and the filter cartridges have seals, end-manifolds, center-pipe manifolds, or other structure that enables them to form fluid connections with the inlet or outlet flows of the pressure vessel.
Such cross flow filtration units are employed, with suitable membrane structures, for a number of separation and purification processes, including gas mixture separation, electrodialysis, microfiltration, ultrafiltration, nanofiltration, and reverse osmosis. On a commercial scale, many of these applications employ cross flow filtration to separate or remove contaminants from a feed fluid at a pressure that may be elevated to the range of several atmospheres (in the case of ultrafltration or nanofiltration), or up to twenty to eighty or more atmospheres (in the case of reverse osmosis of a seawater feed) in order to achieve a desired level of flux across the membranes and suitable yield or quality of permeate. Contaminants such as suspended particles, bacteria, viruses, colloids and the like, and substances such as silica, macromolecules (e.g., biomaterial, complexed or highly hydrated inorganic molecules), as well as herbicides, pesticides, salts, and the like may all be removed in this manner with membranes of suitable porosity/permeability. The semi-permeable membrane "rejects" the targeted contaminants, i.e., prevents the contaminants from passing through the membrane and into the permeate stream.
As cross flow membrane filtration processes have become commercially established as effective methods for fluid purification, basic filter module designs and standardized pressure vessels have come to be the "brick and mortar" of water treatment system or fluid separation system design. In this capacity, they must perform without defects for extended times, processing massive flows of water at the lowest possible cost.
The pressure vessels for these filter cartridges are typically cylindrical tube-like structures of standardized diameter that are configured for large modular installations comprised of many banks of vessels, each vessel holding many filter cartridges. The vessels may be made of fiber-reinforced polymer resin composite material, or may be stainless steel, or may be hybrid structures having composite bodies incorporating steel fittings or fitting reinforcements in a composite body. Such vessels may have plug-type closures or end caps that may be removed to provide "full-bore" access to the interior of the vessel for installation or replacement of the filter cartridges. The filter elements typically have a cylindrical cartridge design with simple end seals to enable long chains or strings of filter elements. This facilitates the loading and unloading of modular filtration elements, and simplifies the construction of large capacity systems. Ports for fluid feed and/or for removal of the permeate and concentrate streams are typically located at, and may be physically incorporated into, the end caps, while each cartridge typically joins to the adjacent one with a sealing coupling at its end, such as a central supply or take-off conduit, or similar end-connector structure of suitable strength and dimensional stability.
Correspondingly, filtration membrane suppliers or OEMs in this field have developed modular membrane cartridge elements that typically include a spiral wound membrane/spacer envelope communicating with a central fluid permeate conduit, some structural body or skeleton that maintains its diametral and length dimensions, and some form of cartridge-to-cartridge coupling. The coupling may, for example, include a male or a female ending, typically with O-ring seals, that joins the permeate collection tubes of adjacent cartridges. Multiple cartridges of this type are assembled together with suitable shims in a pressure vessel to provide a fit that limits axial movement and thus avoids erosion of the seals by movement during extended use. A springy anti-telescope/anti-shock device typically is placed at each end of the chain of cartridges to support and absorb axially-directed forces carried by the cartridge shell. The internal cartridge couplings or end supports of one supplier may not be compatible with those of another supplier, so that, as a practical matter, a large water purification or treatment system may operate using many hundreds of cartridges of a single type from a single supplier.
In the commercially available pressure vessels known to applicant, the feed entrance and exit ports are located such that the feed fluid will flow substantially from one end of the vessel toward the opposite end past successive filter cartridges, and the vessels are sized so that two or more filtration cartridges or elements may be connected in series within the vessel to achieve a desired capacity while limiting the overall capital cost of the filtration system. Typical filtration system designs in use today employ pressure vessels that hold six to eight or more "cartridges" or modular filter elements, and these couple or interfit with each other inside the vessel as described above. An engineer may thus design a system of desired capacity by changing relatively simple parameters, such as the number of vessels of the given length, the number of 48-vessel modules, the feed pump rating, supply conduit size and the like. The modular construction allows one to minimize the number of costly components such as manifolds and pumps, as well as valves and sensors, and to effect relatively simple monitoring and control regimens. It also permits simple servicing and replacement of the filtration elements, which are all identical and are typically sized for convenient handling—e.g., the cylindrical elements are under about a meter in length and are usually ten to fifteen centimeters in diameter. Thus, the module-to-module packing of filter cartridges in long pressure vessels provides a flexible approach for plant designs of different sizes.
While the use of modular arrays of multi-element vessels allows one to scale plant size relatively easily and to connect with upstream and downstream processes, it does not provide much flexibility of the filtration stage itself.
U.S. Pat. No. 4,046,685 issued in 1977 to Desalination Systems, Inc. proposed a system wherein a feed enters at one end of an RO pressure vessel, and a ring (24, shown in FIG. 1 of that patent) is fastened at an intermediate position inside the vessel to rigidly position a front RO membrane cartridge. The downstream end of the permeate pipe of the front cartridge is plugged, as is the upstream end of the permeate pipe of the next cartridge, so that permeate exits the vessel in two places—a first flow of high quality permeate at the inlet end of the vessel and a second flow of lesser quality permeate, collected from the several downstream cartridges, at the distal end of the vessel. That patent also suggests that such an RO vessel and output arrangement be employed in a second stage RO, substituting high rejection membranes to produce a lesser amount of a high quality water at the front end and a greater amount of lesser quality water from the remaining elements at the opposite end of the pressure vessel. This is intended to produce two useable water output streams of different characteristics, e.g., to produce domestic and industrial/agricultural water outputs, respectively, from the same RO plant. However, applicant is not aware of commercial systems of the type indicated in that patent. Instead, modern systems employ "full bore" pressure vessels, as previously described. The cartridges employed in these vessels often have directional seals; the cartridge may be inserted unidirectionally from one end of the vessel, and may be removed, typically several years later when spent, by travel in the same direction out the opposite end of the pressure vessel.
In the modern systems employing long, multi-cartridge pressure vessels, there is a practical limit to the number of filtration elements that can be effectively utilized in this manner within a single pressure vessel. This limit is a consequence of the trade-off inherent in the cross flow filtration process. In a pressurized cylindrical vessel as described above, the feed fluid flows axially along the length of the vessel to reach each successive cartridge, and purified fluid passes through the membrane(s) and is collected as a permeate stream. Seals around the perimeter of each element prevent the feed from bypassing a cartridge, so the concentration of retained contaminants continuously increases in the remaining feed water as it becomes loaded with the "reject" of upstream cartridges. The volume of the downstream feed flow also decreases in moving from the vessel feed inlet to the vessel reject outlet. This double concentration effect increases the osmotic pressure barrier and thus the driving pressure that is needed at the surface of each successive membrane element to produce permeate, and results in different filtration characteristics along the length of the pressure vessel. When plural filter cartridges are placed in series, loss of feed fluid to the upstream permeate outflow, and the cumulative fluid drag or pressure drop along the upstream fluid flow path, also operate to reduce the downstream pressure as well as the fluid velocity of the stream as it traverses the length of the pressure vessel. Each of these factors lowers the productivity or efficiency of the downstream modules and the quality of the downstream permeate. In extreme cases (such as in sea water desalination where the semi-permeable membrane is a seawater RO membrane), the "last" downstream filtration element in a pressure vessel may contribute only a tiny fraction of the total permeate flow compared to that produced by the "first" upstream filtration element in the same vessel. Conversely, the upstream element may experience a higher degree of plugging or fouling early in its life due to the increased through flow it experiences, or various elements may age differently due to the differences in both salinity and cross flow velocity.
In constructing multi-cartridge pressure vessels, the end caps or manifolds with their pipe fittings are appreciably more expensive than the plain cylindrical-walled portions of the pressure vessel. Thus, the cylindrical body of a glass composite pressure vessel rated at 1000 psi may be manufactured for about $20-40 per linear foot (thus, $40-$120 per cartridge), while an end cap with inlet, suitable sealing faces, and permeate and possibly brine outlet connections may cost several hundred dollars, substantially raising the price of the vessel. This suggests that it should be cost effective to extend the length of a pressure vessel to hold more, e.g., 8-10, filter cartridges while still using only two end fittings. However, as discussed above, while the relatively low marginal cost of adding additional filter modules in a linear section of pressure vessel is inviting, a reduction in relative yield and quality occurs with the addition of further filtration elements in the vessel. Moreover, if a designer were to address capacity by using longer vessels to hold more modules, operation at the flows and level of pressure necessary to effect separation at the designed capacity could require much larger pressure pumps and thereby substantially increase energy utilization. The level of required energy may also vary over time depending upon seasonal changes in feed water characteristics, on filter and cartridge characteristics, membrane aging or fouling conditions, and the structural configuration of the system, among other determinants. Cartridges may scale or foul. These factors may therefore combine to drive down performance or increase capital costs, operating costs or both in a way that ultimately requires steady-state operation at less than optimum efficiency or at less than the intended or the rated capacity. For these and other reasons, the capacity of RO pressure vessels remains limited and has become relatively standardized, commonly holding at most around 6-8 filter cartridges in series. Even with such vessels, and the ability to vertically stack banks of many vessels, large warehouse-size treatment buildings are required to house a major RO plant, and better efficiency and/or greater compactness would be highly desirable.
Because cross flow membrane filtration processes such as reverse osmosis (RO) and nanofiltration (NF) are now routinely employed for water desalination and brackish water treatment projects that involve massive volumes of fluid and must operate for many years, the economic consequences can be substantial. These systems may involve large operating costs for energy and chemicals in addition to the initial capital expenses of construction and plumbing, and they require periodic membrane or cartridge replacement. The ever-increasing size of RO and NF projects entering the planning and design stages today requires consideration and implementation of incremental cost saving measures that may, over the lifetime of a project, affect any of these cost components and thus may produce substantial savings for the owner, operator, and/or other customer of the project. The use of conventional, multiple element pressure vessels may in some circumstances lower the capital cost of such systems by providing greater capacity without additional construction costs; however, the compromise of operating efficiency as noted above attendant with the use of such vessels may increase the later operating costs for the same systems. Institutional predispositions or weaknesses within a contracting authority, such as a public water board, as well as the bidding process itself may bias the evaluation of treatment plant designs and result in a failure to fully consider or understand future performance or maintenance cost issues. Nonetheless, current modular filtration systems have become increasingly locked into the use of basic units having these limitations. The consequences for ever-larger RO and NF systems being designed and built today may be substantial.
It would therefore be desirable to provide a multi-cartridge cross flow filter assembly and associated fittings of enhanced design versatility and/or performance.
It would also be desirable to provide basic vessel, filter cartridge and associated fittings, or that provide an increase in vessel scale or filtration capacity without detrimental loss of efficiency.
It would also be desirable to provide basic vessel, filter cartridge and associated fittings that increase output, that reduce operating costs, or that otherwise enhance energy utilization or maintenance efficiency of a plant.
These and other limitations of and deficiencies in the prior art filtration/purification systems are addressed in whole or in part by the improved system designs and methods of this invention.

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