A method for reproducing a recording medium comprising reading out identification data from a recording medium having recorded thereon data and the identification data, which identification data includes entity identification data and detection data. The detection data is generated using at least the entity identification data and indicates whether or not the entity identification data at least is authentic data. The identification recorded on the recording medium is read out, detection data is generated based on the entity identification data of the identification data as read out and the detection data extracted from the read-out identification data is compared to the generated detection data. When, as a result of comparison, the detection data extracted from the read-out identification data is coincident with the generated detection data, the outputting of the data read out from the recording medium is permitted.

There is a contents distributing system for distributing contents data, such as music, over the network, such as EMD (electronic music distribution). With this system, a user terminal device, for example, may access a server device, where the contents data are stored, to download desired contents data. For payment, the private information, such as a credit card number, a secret number or the Web money, is sent from the user terminal device to the server device.
In such system, payment is by transmitting the private information, such as credit card number, secret number or the Web money from the terminal device to the server device, over the network, so that a cumbersome operation is needed in inputting the private information. Moreover, there is a risk that the private information may be illicitly acquired by a third party for unauthorized use.
As a means for combating this problem, there is a payment system employing a pre-paid recording medium. In this system, the remaining recordable volume of the contents data is recorded on the recording medium purchased by the user. When the terminal device accesses a server device to download the contents data desired by the user, data indicating the recordable volume is transmitted from the terminal device to the server device. The terminal device receives the downloaded contents data and the updated data indicating the recordable data volume to record these data on the recording medium.
With the recording medium used in this system, the contents data and the data indicating the recordable data volume need to be updated from time to time, and hence the write-once or rewritable recording medium is used. Consequently, the recordable data volume, recorded on the recording medium, may be manipulated by a user with a malignant intention, as a result of which the contents data may be repeatedly downloaded by the user with a malignant intention, thus detracting from the benefit of the system supervisor or the copyright owner.

Recording medium recording and/or reproduction apparatus, recording and/or reproduction method


A known fuel injection valve that can be secured to a fuel distributor by rotating the fuel injection valve about a longitudinal valve axis. A first electrical contact element extends out of the valve housing, parallel to the longitudinal valve axis. Such fuel injection valves can be electrically contacted by a bank of contacts that can be mounted on the fuel distributor in a direction of the longitudinal valve axis. The novel fuel injection valve includes first electrical contact elements which extend radially outward. By rotating the fuel injection valve about its longitudinal valve axis, an electrically conductive connection can be made between first electrical contact elements and second electrical contact elements that electrically contact the connection in the fuel injection valve. In this way, a simple, very compact, safe and secure electrical contacting of the fuel injection valves is attained. The electrically actuatable fuel injection valve according to the invention is especially suitable for fuel injection systems of mixture-compressing internal combustion engines with externally supplied ignition.

The invention is based on electrically actuatable fuel injection valve. From German Patent Disclosure Document DE 39 07 764 A1, U.S. patent application Ser. No. 463,572, filed Jan. 11, 1990 U.S. Pat. No. 5,016,594, an electrically actuatable fuel injection valve is already known to applicant that can be secured to a fuel distributor by means of a bayonet mount, by rotating it about its longitudinal valve axis. The first electrical contact elements of the fuel injection valves, which protrude from the valve housing parallel to the longitudinal valve axis, are electrically contacted by second electrical contact elements, which are disposed on a contact bank that can be mounted on the fuel distributor in the direction of the longitudinal valve axis.
Contacting the known fuel injection valves electrically requires a great amount of space for installation, and in particular a great height for installation in the direction of the longitudinal valve axes, because the process of joining the contact bank having the second electrical contact elements is effected in the direction of the first electrical contact elements of the fuel injection valve and hence in the direction of the longitudinal valve axes.

Method for electrically contacting an electrically actuable fuel injection valve


A power recovery system is used for reducing the total energy consumption in a process such as an industrial treating process or a fluid refining process including the delivery of a fluid under a high pressure. The power recovery system includes a high-pressure pump for pressuring raw water, a reverse osmosis membrane cartridge for treating high-pressure water discharged from the high-pressure pump with a reverse osmosis membrane to produce treated water, a positive-displacement piston pump for pressuring raw water under the pressure of concentrated water which is discharged from the reverse osmosis membrane cartridge without being treated by the reverse osmosis membrane, and a power recovery pump turbine for boosting the pressurized raw water discharged from the positive-displacement piston pump and adding the boosted water to the high-pressure water discharged from the high-pressure pump. The power recovery pump turbine is actuated by pressurized water generated in the power recovery system.

1. Field of the Invention
The present invention relates to a power recovery system for reducing the total energy consumption in a process such as an industrial treating process or a fluid refining process including the delivery of a fluid under a high pressure. Particularly, the present invention is preferably used for a power recovery system serving as a consumption energy reducing means in a seawater desalination plant which employs a reverse osmosis membrane method for removing salinity from seawater.
2. Description of the Related Art
Industrial treating processes or fluid refining processes that use a high-pressure fluid require high cost of power to refine the high-pressure fluid. Several methods have been attempted to recover energy from the high-pressure fluid after the processes. As a typical example of such processes according to the related art, a seawater desalination plant which employs a reverse osmosis membrane method and its problems will be described below.
A seawater desalination plant which employs a reverse osmosis membrane method is composed mainly of a pretreatment system, a high-pressure pump, a reverse osmosis membrane cartridge, and a power recovery system. When seawater is introduced into the seawater desalination plant, the seawater is processed to have certain water qualities by the pretreatment system, and then delivered into the reverse osmosis membrane cartridge under pressure by the high-pressure pump. Part of the high-pressure seawater in the reverse osmosis membrane cartridge passes through the reverse osmosis membrane against the reverse osmosis pressure and is desalinated, and fresh water is taken out from the reverse osmosis membrane cartridge. The remaining concentrated seawater with a high salt content is discharged as a reject from the reverse osmosis membrane cartridge. The operational costs of the seawater desalination plant include electric expenses as the highest cost, and more than half of the electric expenses are consumed to operate the high-pressure pump for pressurizing the seawater. There have been proposed various power recovery systems for effectively recovering the pressure energy from the high-pressure reject with the high salt content which has been discharged from the reverse osmosis membrane cartridge.
One of the proposed power recovery systems is a Pelton-wheel power recovery system in which the high-pressure reject is converted into a high-speed jet by nozzles, and the kinetic energy of the high-speed jet is recovered by a Pelton wheel and used to assist motive energy of a motor that drives the high-pressure pump. The Pelton-wheel power recovery system will hereinafter be also referred to as "Related art A". In this system, the Pelton wheel and a pump impeller are generally mounted on one main shaft, and their rotational speeds cannot be changed independently of each other. Although the Pelton wheel is highly efficient itself, if the seawater desalination plant that is combined with the Pelton-wheel power recovery system is to be operated according to seasonal variations in plant throughput, then the Pelton wheel occasionally needs to be operated at much lower efficiencies than its highest possible efficiency.
Another power recovery system for recovering energy from a high-pressure reject has a turbine runner and a pump impeller that are mounted on one main shaft as an assembly called a power recovery pump turbine. In the power recovery pump turbine, the turbine is rotated by the high-pressure reject to drive the pump that is used as a booster pump, thereby reducing the power required to operate a high-pressure pump for pressurizing seawater. The power recovery system of this type has two variations. According to one variation, the seawater from the pretreatment system is divided and supplied to the high-pressure pump and the pump of the power recovery pump turbine, and the seawater pressurized by the pump of the power recovery pump turbine is added to the seawater pressurized by the high-pressure pump. According to the other variation, the entire seawater from the pretreatment system is supplied to both the high-pressure pump and the pump of the power recovery pump turbine. The former variation will hereinafter be also referred to as "Related art B", and the latter variation as "Related art C". According to Related art B, if the turbine efficiency of the power recovery pump turbine is low, then the power recovery system fails to recover sufficient power, and because the power recovery pump turbine bears the same head as the high-pressure pump, the power recovery pump turbine tends to adversely affect the entire system if its efficiency is low. According to Related art C, because the entire seawater is supplied from the pretreatment system to the pump of the power recovery pump turbine, the power recovery pump turbine is liable to adversely affect the overall energy efficiency of the seawater desalination plant if its pump has a low performance.
Still another power recovery system comprises a positive-displacement piston pump having a piston that is actuated in a cylinder by a high-pressure reject supplied thereto to recover energy from the reject. The power recovery system will hereinafter be also referred to as "Related art D". It is the general practice to place a low-head variable-speed inverter-driven booster pump downstream of the positive-displacement piston pump in order to compensate for a pressure loss caused by a control valve. It is known in the art that the booster pump needs to be of a special pump structure with a high inlet pressure and requires an expensive mechanical seal having high pressure resistance. The power recovery system possesses relatively low reliability because this system includes more electric devices to be supplied with energy from external sources than other power recovery systems.
The above power recovery systems according to the related art will be described in detail below.
Related Art A:
A power recovery system according to Related art A which employs a turbine for recovering energy from a high-pressure fluid that has been processed in an industrial treating process or a fluid refining process will be described below with reference to FIG. 26 of the accompanying drawings. A seawater desalination plant which employs a reverse osmosis membrane method will be described as a typical example of the industrial treating process, and problems of Related art A will be described in specific detail below.
When seawater 1 is pumped into the seawater desalination plant by an intake pump 2, the seawater 1 is processed to have certain water qualities by a pretreatment system 3, and then pressurized and delivered via a high-pressure line 7 into a reverse osmosis membrane cartridge 8 by a high-pressure pump 5 that is driven by an electric motor 6. Part of the seawater in a high-pressure chamber 9 of the reverse osmosis membrane cartridge 8 passes through a reverse osmosis membrane 10 against the reverse osmosis pressure and is desalinated, and then desalinated water 12 is taken out from the reverse osmosis membrane cartridge 8. The remaining concentrated seawater with a high salt content is discharged under pressure as a reject from the reverse osmosis membrane cartridge 8 into a concentrated seawater line 13. The pressure energy of the high-pressure reject discharged from the reverse osmosis membrane cartridge 8 is recovered as power by a turbine 14 having a rotating impeller. The recovered power contributes to reduction of the drive power generated by the electric motor 6 which is coaxially coupled to the turbine impeller. The reject from which the pressure energy has been removed by the turbine 14 is discarded as a low-pressure turbine reject 15.
For example, it is assumed that a seawater desalination plant including 16 trains of seawater desalination apparatuses combined with the power recovery system according to Related art A produces about 50 MGD (Megagalons per day) and its reverse osmosis membrane cartridges are placed under a pressure of about 7.7 MPa to desalinate 28% of the intake seawater. In this case, the turbine recovers about 2280 kW of energy per train at an efficiency of 88%, and it is possible to reduce the power required to drive the high-pressure pump to about 2090 kW. However, if the turbine efficiency drops by 5% in a case where optimized operation of the turbine is impeded for the reasons described above with respect to Related art A, then the seawater desalination plant fails to recover about 130 kW of energy. As the type of turbine, a Pelton turbine is often used. In this case, the high-pressure reject is ejected as a high-speed jet into the atmosphere and then impinges upon the buckets of the turbine impeller to drive the turbine impeller. When the reject impinges upon the buckets, its pressure drops to the atmospheric pressure. Therefore, the seawater desalination plant requires ancillary facilities such as pumps for discarding the reject from the discharge line.
When the seawater desalination plant is to desalinate 45% of the intake seawater, the turbine recovers about 1080 kW of energy per train at an efficiency of 88%, and it is possible to reduce the power required to drive the high-pressure pump to about 1630 kW. If it is assumed that the turbine efficiency drops by 5%, then the seawater desalination plant fails to recover about 60 kW of energy.
Related Art B:
A power recovery system according to Related art B which employs a mechanical apparatus called "power recovery pump turbine" or "turbocharger pump" will be described below with reference to FIG. 27 of the accompanying drawings. The power recovery pump turbine or turbocharger pump comprises a pump impeller and a turbine impeller which are coupled to each other by a single shaft such that the pump impeller is driven only by the power recovered by the turbine impeller.
When seawater 1 is pumped into the seawater desalination plant by an intake pump 2, the seawater 1 is processed to have certain water qualities by a pretreatment system 3, and then pressurized and delivered via a high-pressure line 7 into a reverse osmosis membrane cartridge 8 by a high-pressure pump 5 that is driven by an electric motor 6. Part of the seawater in a high-pressure chamber 9 of the reverse osmosis membrane cartridge 8 passes through a reverse osmosis membrane 10 against the reverse osmosis pressure and is desalinated, and then desalinated water 12 is taken out from the reverse osmosis membrane cartridge 8. The remaining concentrated seawater with a high salt content is discharged under pressure as a reject from the reverse osmosis membrane cartridge 8 into a concentrated seawater line 13. The high-pressure reject discharged from the reverse osmosis membrane cartridge 8 is introduced into a turbine 14 of a power recovery pump turbine 18 to drive a turbine impeller disposed in a casing of the turbine 14. Thus, a pump impeller in a booster pump 17 that is coupled to the turbine 14 by a rotational shaft 16 is rotated, and the pressure energy possessed by the high-pressure reject is recovered as effective power. The reject from which the pressure energy has been removed by the turbine 14 is discarded as a low-pressure turbine reject 15. The recovered power is consumed to rotate the pump impeller that is coaxially coupled to the turbine impeller. Part of the seawater from the pretreatment system 3 is supplied via a supply line 4 to the booster pump 17, and is pumped by the booster pump 17. The pumped seawater flows through a booster pump outlet line 19 into the high-pressure line 7 where it is added to the seawater from the high-pressure pump 5. The combined seawater is supplied to the reverse osmosis membrane cartridge 8. As a consequence, when the seawater desalination plant is to produce a certain amount of desalinated water, the amount of seawater to be pressurized by the high-pressure pump 5 may be decreased, thus reducing the cost of electric power required to drive the high-pressure pump 5 by the motor 6.
The turbine impeller is driven by the high-pressure seawater that is supplied under a pressure of 7 MPa or higher from the reverse osmosis membrane cartridge 8. Accordingly, there is a narrow choice of the turbine 14. Also, there is a narrow choice of the pump coaxially coupled to the turbine 14 in order to ensure high efficiency.
It is assumed that a seawater desalination plant including 16 trains of seawater desalination apparatuses combined with the power recovery system according to Related art B produces about 50 MGD (Megagalons per day) and its reverse osmosis membrane cartridges desalinate 28% of the intake seawater. In this case, it is possible to reduce the power required to drive the high-pressure pump to about 1960 kW per train. When the seawater desalination plant is to desalinate 45% of the intake seawater, it is possible to reduce the power required to drive the high-pressure pump to about 1570 kW. However, if the pump and turbine efficiencies of the power recovery pump turbine 18 drop by 5% due to the narrow choice of the turbine 14 and the booster pump 17, then the power consumption increases by 120 kW for desalinating 28% of the intake seawater and by 160 kW for desalinating 45% of the intake seawater. Since the latter desalinating process requires a Pelton turbine as the turbine, the seawater desalination plant requires ancillary facilities such as pumps for discarding the reject from the discharge line, and the power recovery pump turbine is expected to be operated at a rotational speed of 5000 rpm or higher.
Related Art C:
A power recovery system according to Related art C which employs a power recovery pump turbine as a high-pressure booster pump will be described below with reference to FIG. 28 of the accompanying drawings.
When seawater 1 is pumped into the seawater desalination plant by an intake pump 2, the seawater 1 is processed to have certain water qualities by a pretreatment system 3, and then pressurized and delivered via a high-pressure line 7 to a booster pump 17 of a power recovery pump turbine 18 by a high-pressure pump 5 that is driven by an electric motor 6. The seawater 1 is then delivered from the booster pump 17 via a booster pump outlet line 19 into a reverse osmosis membrane cartridge 8. Part of the seawater in a high-pressure chamber 9 of the reverse osmosis membrane cartridge 8 passes through a reverse osmosis membrane 10 against the reverse osmosis pressure and is desalinated, and then desalinated water 12 is taken out from the reverse osmosis membrane cartridge 8. The remaining concentrated seawater with a high salt content is discharged under pressure as a reject from the reverse osmosis membrane cartridge 8 into a concentrated seawater line 13. The high-pressure reject discharged from the reverse osmosis membrane cartridge 8 is introduced into a turbine 14 of the power recovery pump turbine 18 to drive a turbine impeller disposed in a casing of the turbine 14. Thus, a pump impeller in the booster pump 17 that is coupled to the turbine 14 by a rotational shaft 16 is rotated, and the pressure energy possessed by the high-pressure reject is recovered as effective power. The reject from which the pressure energy has been removed by the turbine 14 is discarded as a low-pressure turbine reject 15. The recovered power is consumed to rotate the pump impeller that is coaxially coupled to the turbine impeller, thereby further boosting the seawater supplied from the high-pressure line 7. The power recovery system according to Related art C is theoretically as effective as the power recovery system according to Related art B in reducing the power required to desalinate seawater.
Related Art D:
A power recovery system according to Related art D which comprises a positive-displacement power recovery system will be described below with reference to FIG. 29 of the accompanying drawings. In the power recovery system according to Related art D, the high-pressure energy of the reject from a reverse osmosis membrane cartridge is supplied to actuate the pistons in a pair of power recovery chambers of a positive-displacement piston pump, thereby pumping the intake seawater.
When seawater 1 is pumped into the seawater desalination plant by an intake pump 2, the seawater 1 is processed to have certain water qualities by a pretreatment system 3, and then pressurized and delivered via a high-pressure line 7 into a reverse osmosis membrane cartridge 8 by a high-pressure pump 5 that is driven by an electric motor 6. Part of the seawater in a high-pressure chamber 9 of the reverse osmosis membrane cartridge 8 passes through a reverse osmosis membrane 10 against the reverse osmosis pressure and is desalinated, and then desalinated water 12 is taken out from the reverse osmosis membrane cartridge 8. The remaining concentrated seawater with a high salt content is discharged under pressure as a reject from the reverse osmosis membrane cartridge 8 into a concentrated seawater line 13. The high-pressure reject discharged from the reverse osmosis membrane cartridge 8 is introduced through a control valve 20 into a pair of power recovery chambers 21 of a positive-displacement piston pump 23, thereby actuating pistons in the power recovery chambers 21. The reject from which the pressure energy has been removed by actuating the pistons is discarded as a low-pressure turbine reject 15. Part of the seawater in the supply line 4 is pumped by the positive-displacement piston pump 23, and the pumped seawater is discharged to a supply seawater bypass boost line 24, and is finally be added to the high-pressure seawater supplied from the high-pressure pump 5. The pressure of the seawater in the supply seawater bypass boost line 24 is lower than the pressure of the seawater in the high-pressure line 7 because of a pressure loss caused by the reverse osmosis membrane cartridge 8 and the piping, a pressure loss caused by the control valve 20, and a leakage loss caused by leakage of fluid between the power recovery chambers 21 and the pistons disposed therein. In order to combine the seawater in the supply seawater bypass boost line 24 and the seawater in the high-pressure line 7 with each other, a booster pump 17 which is driven by a motor 26 is provided between the supply seawater bypass boost line 24 and a booster pump outlet line 19.
It is assumed that a seawater desalination plant including 16 trains of seawater desalination apparatuses combined with the power recovery system according to Related art D produces about 50 MGD (Megagalons per day) and its reverse osmosis membrane cartridges desalinate 28% of the intake seawater. In this case, it is possible to reduce the power required to drive the high-pressure pump to about 1440 kW per train. When the seawater desalination plant is to desalinate 45% of the intake seawater, it is possible to reduce the power required to drive the high-pressure pump to about 1330 kW. The head required for the booster pump 17 is of a small value equivalent to a pressure loss caused by the piping and the like. However, since the pressure at the inlet of the booster pump 17 is of a high level of about 7 MPa, the booster pump 17 needs to be a special pump having a high-pressure seal structure.


The fluids have an oil-soluble boron content of about 0.001 to about 0.1%, an oil-soluble phosphorus content of about 0.005 to about 0.2%, and either no metal additive content or an oil-soluble metal content as one or more metal-containing additives of no more than about 100 ppm. Included in the fluids are: (a) at least 70 wt % of hydrogenated poly-.alpha.-olefin oligomer fluid with a viscosity in the range of 2-6 cSt at 100.degree. C.; (b) 2-20 wt % of acrylic viscosity index improver; (c) 4-25 wt % of oil-soluble dialkyl ester of a C.sub.4 to C.sub.14 .alpha.,.omega.-dicarboxylic acid with a pour point of -45.degree. C. or lower; (d) ashless dispersant; (e) friction modifier; and (f) oil-soluble inhibitors. The components are such that the fluid has (i) a KV of at least 6.8 cSt at 100.degree. C., (ii) a BV of 15,000 cP or less at -40.degree. C., (iii) a KV at 100.degree. C. of at least 6.0 cSt after 4 hours and at least 5.0 cSt after 20 hours in the Volkswagen taper roller bearing shear stability test. The fluids possess other excellent performance properties.

The continuing development of new power transmission equipment gives rise to demands for new automatic transmission fluids capable of meeting increasingly severe performance requirements sought by the original equipment manufacturers and marketers of power transmission fluids. Among significant improvements in this regard are the ashless or low-ash synthetic base compositions described in U.S. Pat. Nos. 5,089,156 and 5,360,562 to D. R. Chrisope and R. J. Hartley. Those compositions, which utilize among other things mixtures of certain high and low viscosity hydrogenated poly-.alpha.-olefin oligomers and little or no high molecular weight viscosity index improvers, have excellent high and low temperature viscosity properties and excellent shear stability. Nevertheless, further progress in the field requires compositions which not only possess these properties, but which in addition exhibit superior seal performance and superior friction properties.

Substantially metal free synthetic power transmission fluids having enhanced performance capabilities


A planting implement including a toolbar and a seed metering system supported by the toolbar. The seed metering system includes at least one row unit. Each row unit includes a frame, an auxiliary seed hopper supported by the frame, a seed meter fluidly coupled to the auxiliary seed hopper, and a vacuum fan fluidly coupled to the auxiliary seed hopper and the seed meter in a closed fluid system in which the vacuum fan recirculates air through the auxiliary seed hopper and the seed meter.

After a field has been worked, for example plowed, tilled and/or finished, a planting implement, i.e., a planter, may be towed behind an agricultural vehicle to simultaneously create numerous rows of planted seeds by disking furrows and planting the seeds within the furrows via a pneumatic seed planting system. Typically, planters can include one or more main seed tank(s), row units that are distributed across the width of a toolbar, and a pneumatic system to transport the seeds or fertilizer from the storage tanks to the row units. Each row unit generally includes auxiliary seed hoppers, a metering device, discs to cut the furrow in the field, closing discs, and press wheels. Thereby, the row units each respectively open a trench in the field, deposit seeds via the metering device, close the trench, and pack soil onto the seed in order to plant the seeds.
The pneumatic system may include an air pressure differential system, an air compressor system, an electric generator, and various hoses and/or conduits to transport the seeds from the main seed tank(s) to the respective auxiliary seed hoppers. Many modern planters have air pressure differential systems which include a centralized vacuum fan that facilitates seed transportation to the multiple row units. As can be appreciated, the single vacuum fan cannot specifically tailor a variable vacuum pressure for each row unit. Further, if an operator desires to not use one or more of the row unit(s) to plant fewer rows of seed, the single vacuum fan cannot shut off the row unit(s) which are not presently planting seed. Additionally, it is typical for the pneumatic system to be an open airflow system. Meaning, air from the surrounding atmosphere is drawn into the intake of the metering devices, and the single vacuum fan exhausts the resultant pressurized air back into the surrounding atmosphere. This open airflow system may lead to energy loss as well as to the contamination of the surrounding atmosphere due to chemicals present within the airstream. Also, some metering devices can become clogged because debris, for example dust or crop residue, may collect on the air intake port of a respective metering device.
What is needed in the art is a cost-effective and energy efficient seed metering system.


The invention is a method for compensating for fringe visibility errors in a fiber-optic gyro. The light beam phase is modulated utilizing a phase-modulation generating function comprising a stepped waveform with steps of height 2.pi.k-.phi..sub.SE +j.phi..sub.M -.gamma..sub.ZS at time intervals .tau. where a phase step .phi. specified by the phase-modulation generating function is transformed into a change in light-beam phase of (.phi..sub.X /X).phi..sub.X where .phi..sub.X is the change in light phase produced by a phase step X. The integer k takes on the value -1, 0, or 1, j takes on the value -1 or 1, .phi..sub.SE is a phase determined by the fiber-optic gyro, .phi..sub.M is a predetermined phase value, and .gamma..sub.ZS is a phase designed to compensate for the fringe visibility errors. The phase .gamma..sub.ZS represents a small perturbation to the modulation and is a function of zone Z and state S where the zone identifier Z and state identifier S denote one of a plurality of operating conditions of the fiber-optic gyro. The zone identifier Z depends on the relative magnitudes and signs of .phi..sub.SE and .phi..sub.M, and the state identifier S is a function of k and j. Estimates of the Sagnac residual phase compensated for fringe visibility errors are then obtained by adding calculated fringe visibility compensation terms to .phi..sub.SE.

This invention relates generally to fiber-optic gyros and more specifically to the signal processing associated with fiber-optic gyros.
Fiber-optic gyros measure rate of rotation by determining the phase difference in light waves that propagate in opposite directions through a coil wound with optical fiber. Light waves that propagate through the coil in the direction of rotation take a longer time than light waves that propagate through the coil in the direction opposite to the direction of rotation. This difference in time, measured as the phase difference between counter-propagating light waves, is proportional to the angular velocity of the coil.
A typical block diagram for a fiber-optic gyro is shown in FIG. 1. A light source 2 supplies a reasonably coherent light beam to the optical-fiber interferometer 4 which causes the input light beam to be split into twvo light beams that are fed into opposite ends of an optical fiber configured as a coil. The light beams emerging from opposite ends of the optical fiber are recombined into a single output light beam that feeds into the detector 6.
The detected light intensity I (i.e. output of the detector 6) is given by ##EQU1## where I.sub.o is the peak detected light intensity and .theta.(t) is the phase difference between the two beams expressed as a function of time.
The phase difference .theta.(t) typically takes the form EQU .theta.(t)=[.PHI.(t)].sub.mod2.pi. -[.PHI.(t-.tau.)].sub.mod2.pi. +.phi..sub.S +2.pi.n (2)
where .PHI.(t) is the phase-modulation generating function and .PHI.(t).sub.mod2.pi. is the phase modulation introduced by a phase modulator at one end of the fiber-optic coil in the interferometer 4, .tau. is the propagation time through the fiber optic coil, and (.phi..sub.S +2.pi.n) is the so-called Sagnac phase resulting from the rotation of the fiber-optic coil about its axis. The integer n (called the Sagnac fringe number) is either positive or negative and the Sagnac residual phase .phi..sub.S is constrained to the range -.pi..ltoreq..phi..sub.S <.pi..
The output of the detector 6 is high-pass filtered to remove the DC component, then converted to digital form by the analog-to-digital converter 8, and finally processed in the digital processor 10 to yield at the output a measure of the rate and angle of rotation of the interferometer 4. In addition, the digital processor 10 generates a phase-modulation generating function .PHI.(t), the modulo-2.pi. portion of which is converted to analog form by the digital-to-analog converter 12 and supplied to the phase modulator in the interferometer 4.
The phase-modulation generating function .PHI.(t) typically consists of a number of phase-modulation components among which are .PHI..sub.SE (t) and .PHI..sub.M (t). The phase-modulation component .PHI..sub.SE (t) is typically a stepped waveform with steps that change in height by -.phi..sub.SE at .tau. intervals where .phi..sub.SE is an estimate of .phi..sub.S. Thus, the .PHI..sub.SE (t) modulation cancels in large part .phi..sub.S. The accurate measurement of the uncancelled portion of the Sagnac residual phase .phi..sub.S is of great importance in that it is the quantity that is used in refining the estimate of the Sagnac phase and generating the .PHI..sub.SE (t) phase-modulation component.
The accurate measurement of the uncancelled portion of the Sagnac residual phase is greatly facilitated by choosing the .PHI..sub.M (t) phase-modulation component such that [.PHI..sub.M (t)-.PHI..sub.M (t-.tau.)] is equal to j.phi..sub.M where the permitted values of j are the values -1 and 1 and .phi..sub.M is a predetermined positive phase angle somewhere in the vicinity .pi./2 radians where the slope of the cosine function is greatest. This effect can be achieved, for example, by having .PHI..sub.M (t) be a square wave with amplitude .pi./2 and period 2.tau..
While it might appear that the best choice for .phi..sub.M would be .pi./2 where the slope of the cosine function is greatest, it has been shown that values between .pi./2 and .pi. provide better noise performance.
The .PHI..sub.M (t) modulation can also be a stepped function wherein the phase increases or decreases at .tau. intervals by .phi..sub.M. Under these circumstances, EQU [.PHI.(t)].sub.mod2.pi. -[.PHI.(t-.tau.)].sub.mod2.pi. =2.pi.k-.phi..sub.SE +j.phi..sub.M (3)
Substituting these expressions in equation (2), we obtain EQU .theta.=2.pi.(k+n)+j.phi..sub.M (4)
The equation above is the ideal phase difference equation, where .phi..sub.S -.phi..sub.SE =0. For fiber-optic closed-loop calculation, two control parameters are inserted into the phase difference equation with the following result: ##EQU2## The rebalance phase error .epsilon. is given by EQU .epsilon.=.phi..sub.S -.phi..sub.SE (6)
and the phase modulator scale factor error .delta./.pi. is given by ##EQU3## where .phi..sub.X is the change in light phase caused by a phase modulation step intended to produce a change of X radians. Note that if .phi..sub.x were correct and equal to X, then .delta. would be equal to zero.
The parameters .phi..sub.SE and .phi..sub.X (for a particular X) are driven by control loops to force the two demodulated signals to zero. TFhe rebalance phase demodulation equation is ##EQU4## and the scale factor demodulation equation is ##EQU5## where p.sub.kj is the probability of occurrence of each state, D.sub.kj is the scale factor demodulation polarity, I.sub.kj is the detected light intensity which may be a function of k and j, and I.sub.av is the average of I.sub.kj. The quantity I.sub.kj -I.sub.av is the amplitude of the signal that results from the high-pass filtering of the output signal from detector 6.
Fiber optic gyros generally employ broadband light sources in order to avoid polarization cross-coupling effects as the light propagates through the fiber. As a result, however, coherence is lost as non-reciprocal phase shifts between the clockwise and counter-clockwise beams are introduced. This leads to the "fringe visibility effect" whereby the interference pattern between the two beams loses contrast as the difference in optical paths increases.

Method for compensating for fringe visibility errors in a fiber-optic gyro


An object of the invention is to provide an optical fiber coating removing apparatus which can remove coating from an optical fiber preform without damaging the optical fiber surface. The apparatus is excellent in workability because positioning or the like for coating removal easily. The invention provides an optical fiber coating removing apparatus for holding coating 1b of an end portion of an optical fiber 1 between a pair of coating removing blades and removing the coating 1b from the optical fiber 1 with the pair of the blades. In each blade 11, 11′, a blade pressing plate 12, 12′, a semicircular blade 13, 13′ having a semicircular eating blade portion 13a, and a flat blade 14, 14′ having a straight-line eating blade portion 14a having a triangular section are integrally laminated onto a blade bearing plate 15, 15′ in that order. The coating 1b is removed without damaging the surface of the optical fiber.

When optical fibers are connected to each other, or when an optical fiber is connected to an optical component, first the coating in an end portion of each optical fiber is removed to expose the glass portion thereof. After that, the surface of the glass portion of the optical fiber exposed after the coating removal is cleaned by wiping off residual parts of the coating or the like with apiece of gauze or the like impregnated with a solvent. After that, a part of this glass portion is cut off with a fiber cutter (creeper) so that the glass portion has a predetermined exposed length. Thus, a mirror-finished cut surface is obtained. Such a series of steps for terminal working in the end portion of the optical fiber are carried out individually with tools special to those steps respectively, or carried out with an automated apparatus.
Removal of coating from an optical fiber is carried out, for example, by nipping the coating of a single-core optical fiber with a pair of coating removing blades, making the blades eat into the coating, and pulling the coating from the optical fiber with the coating removing blades. FIG. 8 is a view showing examples of removal of coating from a conventional optical fiber. FIG. 8(A) shows an example of removal of coating with flat blades, and FIG. 8(D) shows an example of removal of coating with semicircular blades.
As shown in FIG. 8(A), when coating 1b of an optical fiber 1 is removed with a pair of flat blades 2, the upper and lower flat blades 2 and 2 are made to eat into the coating 1b shallowly enough not to come into direct contact with the surface of a glass portion 1a of the optical fiber 1. In this state, when the optical fiber 1 is pulled in the left direction shown by the arrow in the drawing, the coating 1b is ripped down at the place where the blades eat. Then, the coating 1b is removed while forming a swelling on the right of the blades.
When the outer diameter of the glass portion 1a is 0.125 mm and the outer diameter of the coating 1b is not larger than 0.3 mm, the distance between the pair of flat blades 2 will be about 0.2 mm, and the distance between the glass portion la and each flat blade 2 will be about 0.04 mm.
When the thickness of the coating 1b of the optical fiber 1 is small, pulling out the coating 1b may make the optical fiber 1 shake up and down. When the coating 1b is pulled out in the state where the optical fiber 1 shakes up and down, the pair of flat blades 2 and 2 further eat into the coating 1b so that the surface of the glass portion 1a of the optical fiber 1 is brought into contact with the blades. Thus, the surface of the glass portion 1a is apt to be damaged. When the surface of the glass portion 1a is damaged, the strength in connecting optical fibers to each other by fusion splicing is lowered so that the connection may be broken easily.
It is therefore known that a resin layer is added to a coating portion to be removed so that the thickness of the coating is increased, and the coating 1b is removed together with the added resin layer (see Japanese Patent Laid-Open No. 94925/1994). However, it requires extra labor to form the coating resin layer additionally for coating removal. In addition, when the upper and lower flat blades 2 and 2 are made to eat into the coating 1b, the sectional shape of the coating 1b becomes an elliptic shape as shown in FIG. 8(B). When the coating 1b is pulled out in this state, the end portion from which the coating 1b has been removed is expanded like an elliptic trumpet as shown in FIG. 8(C). Thus, there is also a problem that failure in shape is apt to occur in a molding step in which glass portions 1b are connected to each other by fusion splicing and the fusion splicing portion thereof is covered with resin or the like.
As shown in FIG. 8(D), when coating is removed with a pair of semicircular blades 3 and 3, first, the semicircular blade portions are made to eat into the coating 1b shallowly enough not to come into direct contact with the glass portion 1a. The semicircular blades 3 are steadier than the flat blades 2 when the optical fiber is pulled out. Thus, it is difficult for the optical fiber surface to abut against the blades.
However, when the optical fiber 1 is pulled out in the left direction shown by the arrow in the drawing, the coating 1b is ripped down at the place where the blades eat into the coating 1b, coating dust 1c is collectively concentrated on the right side of the blades. When the coating dust is concentrated, the pulling resistance increases so that it becomes difficult to pull out the optical fiber 1. When the optical fiber 1 is pulled forcedly, the optical fiber 1 will be broken. In addition, when the adhesive force between the coating 1b and the glass portion 1a is great, the coating dust is crushed to powder to increase the residual part of the coating 1b adhering to the glass portion 1b. Thus, the workability to remove the coating dust (residual part) deteriorates.
In order to facilitate the removal of coating from an optical fiber, there is also known a technique in which a heater is disposed in a coating removing apparatus and heating by the heater is used to weaken the adhesive force between the optical fiber and the coating. However, the aforementioned problem in coating removing blades themselves has not been solved.
It is an object of the present invention to provide an optical fiber coating removing apparatus which can carry out coating removal easily without damaging the surface of a glass portion of an optical fiber when the coating of the optical fiber is removed therefrom.
Further, it is another object of the present invention to provide an optical fiber coating removing apparatus which is excellent in workability because it can carry out positioning or the like for removing the coating of the optical fiber easily.


An adiabatic liquid volume sensor system is described, which employs a main chamber in a back-to-back configuration with a reference chamber of known volume. The system measures liquid volume in the main chamber by making low frequency acoustic measurements of the acoustic pressure differences in the two closed chambers when driven with a sinusoidal frequency from the same speaker. Pressure transducers in each chamber measure acoustic adiabatic pressures in each chamber. The ratio of these pressures multiplied by the known volume of the reference chamber yields the volume of gas in the main chamber. The volume of liquid is equal to the known volume of the main chamber minus the calculated gas volume.

The present invention relates to volume measuring sensors, and more particularly to a sensor for measuring the volume of air or ullage in a container or a tank, thereby providing an indication of the volume of a liquid, powder or solid occupying the remaining volume of the container.
Several factors have come to the fore in recent years to suggest that a new design for a fuel quantity gauge is becoming a necessity. With the advent of consumers desiring smaller automobiles, designers would like the flexibility of employing convoluted fuel tanks to achieve space efficiency. This will necessitate a change from the simple fuel level gauges in use today.
Consumers, having voiced their desire for longer and more inclusive warranties, are getting such from automobile manufacturers. As a consequence, manufacturers are looking for methods to lessen repair costs wherever possible. Presently if an automobile is brought in for repair because of a defective fuel gauge, the entire fuel tank is replaced. The cost of dissecting the old fuel tank and repairing the gauge is prohibitive. Manufacturers would like externally mounted or easily removable fuel sensors so that the good fuel tank would not have to be discarded, thereby reducing warranty repair costs.
An unlevel vehicle and/or fuel sloshing contribute sources of error to fuel level gauges. Considering the increasing amount of stops and starts for today's commuting driver, the fuel sloshing could render the fuel gauge inaccurate for a large fraction of the time. This enhances the need for a level and sloshing insensitive fuel quantity sensor.
The new dashboard displays can display a high degree of accuracy in their readouts. So much so, that now the limiting factor in the accuracy of reading the remaining fuel is no longer in the display but in the fuel quantity gauge itself. Car manufacturers would like more accurate fuel gauges.
These four compelling reasons indicate the definite need for a new or improved fuel quantity gauge.
Conventional gauges have been used in the measuring of fuel for years. The automobile with its relatively quiescent journey and limited elevation angle, typically employs the mechanical float sensor. This sensor detects level of fluid in the tank and is inexpensive. A simple mechanical float fuel sensor consists of a float (which always rides at the level of the fuel) and vertical rails which constrain the float. For a reference see E. W. Pike et al., "Investigation of Fuel Quantity Measuring Techniques," DTIC-AD712120, USAF-AMC Wright Patterson AFB, Ohio, June 1952. This sensor produces either a changing voltage or current as the float moves up and down along the rails. There have been numerous advances in the mechanical float sensor. However, most mechanical float sensors tend to suffer from the following general disadvantages: (1) Mechanical float sensors required some electricity within the fuel tank, disadvantageous from a safety standpoint. (2) Mechanical mechanisms of any sort break down with much higher regularity than any other system having no moving parts. (3) Mechanical floats have lower accuracies than other fuel gauges available today. (4) Mechanical float gauges measure only fuel level. This is a disadvantage as fuel sloshing, inclining of the road, and the convoluted fuel tank shapes of today decrease the accuracy of fuel level as a measure of fuel quantity.
Some aircraft use mechanical float sensors, but most use a coaxial capacitive sensor. Whichever sensor is used, a matrix of these sensors (from 4 to 12, typically) is typically used within each fuel tank inside the aircraft. There are several separate fuel tanks within an aircraft to take best advantage of this limited volume available in the wings and fuselage. This matrix of sensors and averaging electronics is required to allow some measure of accuracy during maneuvering and climbing. The capacitive sensor is also more accurate than the mechanical float sensor and can therefore provide better fuel management and less likelihood of running out of fuel. However the capacitive sensor is more expensive than the mechanical float sensor, making a matrix of such sensors prohibitively expensive for use in automobiles. Microbial growth in the fuel tank has been shown to affect the accuracy of this sensor. For references see W. B. Engle and R. M. Owen, "Electrical and Physical Nature of Microbial Membranes Implicated in Aircraft Fuel Quantity Probe Malfunction," SAE-710439, National Air Transportation Meeting, Atlanta, Ga., May 1971; J. Huddart, "An Alternative Approach to Fuel gauging," ASE-790138, Society of Automotive Engineers, Detroit, Mich., February/March 1979; K. Suzuki, T. Tomoda, and S. Momoo, "A Highly Accurate Fuel Level Measuring System," SAE-871961, Passenger Car Meeting, Dearborn, Mich., October 1987; P. Weitz and D. Sale, "Effects of Anti-Static Additives on Aircraft Capacitance Fuel Gauging Systems, AFWAL Wright Patterson AFB, Ohio, Technical Report #AFWAL-TR-80-2058, June 1980.
A fiber optic liquid level gauge is described in J. W. Berthod, "Fibre Optic Intensity Sensors," Photonics Spectra, 22(12), 125–138 (December 1988), and utilizes two fibers, a prism, an LED, and a detector. Multiple fiber sensors, each of different length, can be employed to provide an incremental level capability. The disadvantages of the fiber optic fuel gauge are: 1) the sensor must be located inside the tank, 2) films can form on the prism and foul the sensor, 3) the fiber optic sensor is a discrete sensor, and 4) the fiber optic sensor is a level sensor only.
There are two techniques associated with another known fuel sensor, the Boyle's Law or pressure fuel quantity gauge. (For references, see: H. Garner and W. Howell, "Volume Fuel Quantity Gauge" Patent Application, NASA-CASE-Lar-13147-1, Ser. No. 06/643/523 filed Aug. 23, 1984 and now abandoned. Takebayashi, "Volume measurement of liquid in a deformed tank," SAE-871964, Passenger car meeting, Dearborn, Mich., October, 1987.) The first technique (the Beckman method) uses isothermal compression to measure the volume of the gas. Any isothermal (constant temperature) change in volume is accompanied by a change in pressure. Measuring this pressure change, as a piston which is connected to the system collapses its volume, yields a measure of the entire tank volume. A major drawback of this technique is that it cannot work in a tank that has vent holes or leaks of any kind. Such leaks would not allow the pressure build up that is so critical to the measurement. A second method, proposed by Wantanabe and Takebayashi, id., uses an adiabatic (no heat flow) process and a step function of pressure to determine the volume of the air in the tank. This method can deal with small, medium, and large holes in the tank. The effect of leaks in the tank do not alter the outcome of the gauge; they only modify the relaxation time and damping of the pressure pulse in the tank. By noticing the speed of decay of the pressure after the step response, the gas volume can be determined. The disadvantages of this system are (1) the system is bulky and heavy, (2) the adiabatic system requires more complex electronics, and (3) the pistons and valves involved together with the electronics cause this gauge to be very expensive compared to other automobile fuel gauges.
It is therefore an object of the present invention to provide an improved system for measuring the gas volume in a closed container, which is reliable and relatively inexpensive to manufacture.
A further object is to provide an improved adiabatic pressure system for measuring the quantity of a liquid, solid or powder in a closed container of known empty volume.
Yet another object of this invention is to provide an improved fuel quantity gauge system for vehicles.

Acoustic adiabatic liquid quantity sensor


A card edge connector includes a longitudinal housing with a pair of sidewalls and an inserting slot therebetween, a plurality of contacts and three metallic retainers, each of the retainers has a base portion retained in the insulative housing and a pair of board locks defining a central line L in a vertical direction perpendicular to the longitudinal direction. The retainer includes a first retaining portion and a second retaining portion disposed at both sides of the central lines L and different from each other.

1. Field of the Invention
The present invention relates to card edge connectors, more particularly to a card edge connector with an improved retainer.
2. Description of Related Art
Card edge connectors are employed widely in computers to receive a memory card, graphic card, network interface et al. The card edge connector as described in U.S. Pat. No. 7,708,599B2 has an elongated housing, a plurality of contacts retained in the housing for electrically connecting a corresponding memory card, and a pair of ejector mechanisms attached at two opposited ends of the housing for locking the memory card or pushing the memory card out. The housing has a pair of side walls with a plurality of passageways for receiving contacts, a central slot between the side walls for receiving the memory card and a pair of tower portions at two ends thereof. At least one pair of metallic retainers is retained in the bottom of the housing for retaining the card edge connector on a printed circuit board (PCB).
However, the retainer has a pair of retaining barbs symmetrically interfering with the insulative housing, thereby easily being pulled out and destroying inner sides of the insulative housing, especially when the memory card is repeatedly pulled from the card edge connector or the card edge connector is rocked by an overlarge force accidentally.
Therefore, an improved card edge connector and an improved retainer thereof are desired to overcome the disadvantages of the related arts.

Card edge connector with improved retainer and retainer thereof


A method for navigation system modifies a route to the destination by allowing a user to select a type of items or conditions to be avoided from the route. The method includes the steps of displaying a set of data indicating items that a user will encounter when the user follows the calculated route, prompting the user to select a type of the item to be avoided in a new route to the destination, and recalculating the new route according to the user's selection and guiding the user to the destination through the new route. The navigation system displays the set of items which is classified into distance ranges each representing a range of distance from a current user position where each item is represented by a corresponding icon.

Modern vehicles are equipped with sophisticated electronic devices such as multimedia entertainment systems, GPS navigation systems, Internet access devices, and the like. This invention is directed to a display method and apparatus for navigation system for guiding the user to the destination and for displaying traffic information which is typically implemented in such a vehicle electronic device, although the present invention is not limited to the automobile use. This invention can also be applied to a hand-held navigation system, remote terminal, PDA (personal digital assistant), etc. However, for the convenience of explanation, the present invention will be described with respect to a vehicle navigation system.
When driving an automobile, a user wants to reach the destination quickly and smoothly. A user uses the route calculation function of the navigation system to obtain the effective route to a particular destination. In this function, the processor provided in the navigation system calculates an optimum route to the destination. However, because of various traffic incidents, such as traffic jams, accidents, construction, etc., it is sometimes difficult to enjoy smooth driving to the destination. Thus, when driving an automobile to the destination guided by a vehicle navigation system, a user wants to know whether there are any traffic incidents that may affect his/her travel to the destination.
Today, there is a radio communication service which provides traffic information to subscribed members through a wireless transmission or a telephone network. If a user is a member of such a service, he is able to receive the ongoing traffic information through the vehicle navigation system, a portable navigation device, or the like, having a radio transmitter or an Internet access capability. For example, such traffic information (typically depicted by traffic incident icons) will be combined with a map image of an area where the user is currently located.
The traffic conditions can be classified into several categories. For example, the condition is conceivable wherein one vehicle or more vehicles stalled on the middle or proximate with the calculated route for any reason. Another condition is that two or more vehicles collide on or proximate to the calculated route. Still another condition is where traffic construction is in progress while automobile accidents are not involved. Still another condition is that the traffic is extremely slow even though no accident or construction exists but only because there are too many vehicles on the road at the same time. There may be still other conceivable traffic condition types.
Such types of traffic condition are relevant when the user wants to determine which route to take to reach the destination. Each traffic type can pose different consideration in determining the specific route to the destination. For example, the user may reason that the problem associated with a stalled vehicle can be quickly eliminated while the problem due to a road construction may be long-lasting. If the user makes such determination, the user may decide to ignore the stalled vehicle in evaluating the route to the destination but try to avoid the road construction.
Traffic maneuvers can pose similar problems as well. Traffic maneuvers refer to the operation of the vehicle in turning or stopping, etc. When the user wants to avoid making a left turn since the user is uncomfortable with the move, the user may want to make an alternative route that does not involve or decreases the instances of left turns. Still another situation where the user wants to avoid a specific maneuver is when the user knows that making the particular maneuver will lead to an undesirable area or condition. For instance, the user may know that by making a right turn at a particular intersection, he will get into a bumpy road. Even if the bumpy route requires less travel time to the destination, the user may want to avoid damages to his vehicle or discomfort in driving. Thus, the user may want to change the route to avoid the bumpy road.
The user may also wish to eliminate a certain category of point of interest ("POI") from a POI list so as not to display the particular category of POIs. The navigation system is capable of listing various types of POIs along the route. However, because there are many types (categories and sub-categories) of POI, the navigation system displays a long list of POIs, which may become difficult for the user to find the desired POI data. Such a long list of POIs can be distracting to select a desired POI type from many entries of POI in the list, the user may wish to limit POI type to be displayed on a screen. For example, the user may want to know only about gas stations along the route. In that case, he may wish to eliminate such types of POIs as food or shopping area, or the like, from the POI list.
As described above, the user desires to use his discretion in determining which route to take or not to take by limiting or avoiding particular traffic incidents or traffic maneuvers. The user may also wish to eliminate certain POI types to obtain a tidy view on a display. The process of limiting or avoiding particular traffic conditions and maneuvers and POI types must be performed with minimum distraction to the user so that the user can concentrate on driving. The process must also allow the user to specify the conditions to a reasonable detail at a glance. Thus, there is a substantial need for a navigation system that allows the user to easily limit or avoid particular traffic conditions and maneuvers.

This patent is subject to a terminal disclaimer.

Navigation system allowing to remove selected items from route for recalculating new route to destination


A stereoscopic image of an object is focused on an image pickup device based on the degree to which left and right images of the object are coincident on the image pickup device. Signals produced by the image pickup device that represent the left and right images are compared with each other to develop a control signal that indicates the coincidence of the left and right images on the image pickup device, and the spacing between the image pickup device and an optical element that directs the images onto the device is changed in response to the control signal to increase the coincidence. Two alternative types of comparison are performed, each of which indicates the degree of coincidence (and hence the quality of focus) of the left and right images on the image detector. In one approach, the left and right images are compared to determine their cross correlation on the image pickup device, and the spacing is changed to maximize the correlation. Alternatively, the comparison determines the difference between the left and right images on the image pickup device, and the spacing is changed to minimize the difference. The focusing technique is useful in, e.g., the optical system of an endoscope. Rangefinding and videometry are also performed to determine the distance to the object being viewed, as well as its position and size.

This invention relates to focusing a stereoscopic optical system. The invention also relates to rangefinding and videometry in an imaging system.
Stereoscopic optical systems are used in a variety of applications. One environment in which stereoscopic (i.e., three-dimensional) viewing has become useful is the field of endoscopic surgery. During this type of surgery, an endoscope is inserted into the body through a small puncture opening to allow the user to visualize the surgical site without fully opening the wound. The endoscope supplies light to the surgical site through a set of optical fibers that extend along the length of the endoscope. An image pickup device (such as a solid-state sensor, e.g., a charge-coupled device or CCD) receives optical images of objects in the surgical site from an optical assembly, and converts the images to electrical signals for visualization on an electronic display. The image pickup device can be located at the distal tip of the endoscope, in the proximal, handle end of the endoscope, or anywhere in between.
Stereoscopic optical systems produce a video image of an object by acquiring separate left and right images of the object from two different viewing angles. The systems display the right image to the observer's right eye, and separately display the left image to the observer's left eye to provide a three-dimensional view of the object.

Stereoscopic autofocusing based on comparing the left and right eye images


A method enables a gas turbine engine to be operated. The method includes directing fluid flow from a source into an inlet of a valve, channeling the fluid flow entering an inlet portion of the valve towards an outlet portion of the valve such that a direction of the fluid flow is changed within the inlet portion, and controlling the amount of fluid flow entering the outlet portion of the valve by selectively positioning a valve disk coupled within the inlet portion of the valve by a valve disk axle. The method also comprises channeling the fluid flow from the inlet portion of the valve through the outlet portion of the valve and into a fluid supply pipe, wherein the valve outlet portion has a substantially right cylindrical shape such that a direction of fluid entering the body outlet portion remains substantially constant therethrough.

This invention relates generally to gas turbine engines and more particularly, to valve assemblies used to regulate fluid flow for a gas turbine engine.
Gas turbine engines typically include an engine casing that extends circumferentially around a compressor, and a turbine including a rotor assembly and a stator assembly. Within at least some known engines, a plurality of ducting and valves coupled to an exterior surface of the casing are used to channel fluid flow from one area of the engine for use within another area of the engine. For example, such ducting and valves may form a portion of an environmental control system (ECS).
At least some known valve assemblies are used to control fluid flow that is at a high temperature and/or high pressure. Such valve assemblies include a substantially cylindrical valve body that is coupled between adjacent sections of ducting. The valve body includes a valve sealing mechanism that is selectively positionable to control fluid flow through the valve. More specifically, at least some known valves includes a piston/cylinder arrangement that is positioned external to the valve body and is coupled to the valve sealing mechanism to provide the motive force necessary to selectively position the valve sealing mechanism.
Because the piston/cylinder arrangement is offset from the main valve body, a center of gravity of the valve assembly is typically displaced a distance from a centerline axis of the valve body. Such an eccentric center of gravity may induce bending stresses into the valve assembly, adjoining tubing, and supporting brackets during engine operation. Depending on the application, the physical size and weight of the piston/cylinder arrangement may also present difficulties during the duct routing phase of the engine design.

Methods and apparatus for regulating gas turbine engine fluid flow


The present invention relates to an anti-microbial composition and method of use thereof. In particular, the present invention relates to an anti-microbial composition comprising farnesol and cetrimide.

Since their discovery during the 20th century, antimicrobial agents (antibiotics and related medicinal drugs) have substantially reduced the threat posed by infectious diseases. However, it is well documented that in recent times numerous microbes, in particular bacteria, have become resistant to particular antimicrobial agents due to their overuse. Accordingly, there is a continuing need for new anti-microbial agents.
One area that is of particular important is in the area of infection control. Practices, such as hand washing and changing gloves before and after contact with subjects infected with microbes, are critically important in maintaining sterile environments and restricting the spread of disease. Antimicrobial agents, in particular antiseptics, are often used in these environments; however, their continued use has also seen a reduction in their efficacy.
Consequently there is a need for a general use antimicrobial agent that can be used in clinical settings i.e. the treatment of infections, wounds and the like as well as in general infection control e.g. cleaning/sterilising hard surfaces, hand washing and instrument treatment.


A composition for cross-linking of ethylene.polymer comprises 2,4-diphenyl-4-methyl-1-pentene and at least one peroxide selected from the group consisting of [1] peroxides represented by the formula (I): ##STR1## (wherein R.sup.1 stands for one member selected from the group consisting of alkyl groups, aryl groups, and alkyl-substituted aryl groups having 1 to 9 carbon atoms, R.sup.2 for one member selected from the group consisting of phenylene group, ethylene group, --C.tbd.C--, and alkyl groups, aryl groups, and alkyl-substituted aryl groups having 1 to 9 carbon atoms, and n for 1 or 2) and [2] peroxides represented by the formula (II): ##STR2## (wherein two R.sup.3 's independently stand for one member selected from the group consisting of alkyl groups, aryl groups, and alkyl-substituted aryl groups of 1 to 9 carbon atoms or jointly stand for an ethylene group, R.sup.4 and R.sup.5 independently stand for a linear or branched alkyl group of 1 to 6 carbon atoms or --(CH.sub.2).sub.m C(O)OR.sup.6 [wherein R.sup.6 stands for an alkyl group of 1 to 4 carbon atoms and m for an integer in the range of 1 to 3] or jointly for a cyclohexane ring or a cyclododecane ring unsubstituted or substituted with 1 to 3 alkyl groups of 1 to 4 carbon atoms); a method for cross-linking an ethylene.polymer by the use of the composition mentioned above, a method for cross-linking an ethylene.polymer using the composition and a cross-linkable composition comprises an ethylene.polymer and the composition.

1. Field of the Invention
This invention relates to a composition for cross-linking ethylene.polymer which enables an ethylene.polymer to be cross-linked by heating while simultaneously retarding scorch and enhancing the degree of cross-linking, and to a method for cross-linking ethylene.polymer.
This invention further relates to a composition for the production of a cross-linked ethylene.polymer, which composition retains a liquid state at normal room temperature, exhibits only slight volatility, and exhibits high aging stability.
2. Description of the Prior Art
A well-known problem in the production of shaped articles of a cross-linked ethylene.polymer is that the compound suffers scorching in the molding device to such an extent that the appearance of the molded article is degraded, the amount of the compound extruded becomes irregular, and the products come to lack uniformity.
A number of methods are already known for preventing the compound from scorching in the molding device. For example, Japanese Patent Publication SHO 54(1979)-8500 discloses a method for preventing scorch by addition of a selected vinyl compound such as, for example, .alpha.-methylstyrene or an acrylic ester. U.S. Pat. No. 3,335,124 discloses a method for preventing scorch by addition of a sulfur compound. U.S. Pat. No. 3,202,648 discloses one based on the addition of a nitrogen compound, and Japanese Patent Publication SHO 47(1972)-36866 discloses one based on the addition of a phenol type compound.
Dicumylperoxide (hereinafter referred to as "DCP") is commonly used as a cross-linking agent for polyethylene. Since this compound has a melting point of 38.degree. C. to 40.degree. C. and is in a solid state at room temperature, it is liable to be contaminated with foreign matter during handling. This foreign matter can not be detected. Mixing of ethylene.polymer with the DCP is generally carried out using an extruder or the like. For the DCP to be supplied at a fixed speed, it has to be melted by heating. The use of DCP therefore adds to the number of process steps and requires measures for operational safety.
For the solution of this problem, it has been proposed to use for cross-linking an organic peroxide which is in a liquid state at room temperature. Japanese Patent Publication HEI 2(1990)-031106 discloses an organic peroxide mixture consisting of 25 to 10% by weight of bis(.alpha.-t-butylperoxyisopropyl)benzene and 75 to 90% by weight of isopropylcumyl-t-butylperoxy and Japanese Patent Public Disclosure SHO 54(1979)-132644 discloses a DCP substituted with an alkyl group.
Joint use of an organic peroxide and 2,4-diphenyl-4-methyl-1-pentene (hereinafter referred to as "MSD") in the curing of an unsaturated polyester resin has been disclosed (Reinforced Plastics, Vol. 29, No. 8, pp. 357 to 362), as has the joint use of an organic peroxide and MSD for the purpose of lowering the molecular weight of a polymer resulting from the polymerization of a vinyl monomer such as styrene (Japanese Patent Publication SHO 55(1980)-6895).
The method of Japanese Patent Publication SHO 54(1979)-8500 is effective for retarding scorching but has little or no effect toward enhancing the degree of cross-linking. .alpha.-methylstyrene and acrylic ester are low molecular weights and, therefore, are susceptible of volatilization. They are volatilized, therefore, while they are being mixed with the ethylene.polymer or while the composition produced by the mixing is being stored and are degraded in their ability to retard scorching and are apt to cause inconsistency in the quality of the cross-linked polymer.
The methods of U.S. Pat. No. 3,335,124, U.S. Pat. No. 3,202,648, and Japanese Patent Publication SHO 47(1972)-36866 are useful for retarding scorching. However, these methods have a disadvantage of slightly lowering the cross-linking degree. Further, the compounds used in these methods have toxicity.
As regards the organic peroxides which are in the liquid state at normal room temperature, it is preferable during winter to use an organic peroxide having a lower melting point than the organic peroxides disclosed in Japanese Patent Publication HEI 2(1990)-31106 and Japanese Patent Public Disclosure SHO 54(1979)-132644. Furthermore the organic peroxides which are liquid at room temperature and have a low vapor pressure are required. Further, it is required that such liquid peroxides don't suffer yellowing and lowering of active oxygen during storage.
The purpose of the using MSD during the curing of an unsaturated polyester is to delay the curing time and lower the temperature of generated heat. The heat generation temperature is governed by the polymerization conversion rate. It is evident, therefore, that MSD only functions to inhibit the polymerization. In the polymerization of styrene, for example, MSD is used as a chain transfer agent for the purpose of lowering the molecular weight.

Composition for cross-linking of ethylene-polymer, method for cross-linking ethylene-polymer, and cross-linkable composition


A routing system transfers data packets of real time communication services of a call, and includes a converter receiving media gateway control protocol encoded first control data and processing the first control data to obtain second control data. The system, based on the first control data, allocates a first transport address for a first routing port for incoming data packets, and allocates a second transport address for a second routing port for outgoing data packets. A central control entity controls a central control entity controlled network of forwarding elements, and determines a static pathway through the network of forwarding elements based on the second control data. A first end of the static pathway corresponds to the first routing port and a second end corresponds to the second routing port. The central control entity controls a data plane flow of a stream of the data packets along the static pathway.

The Third Generation Partnership Project (3GPP) standard Release 4 architecture utilizes a mobile switching centre server (MSC-S) as controlling element and a media gateway node (MGW) to do the data plane handling of packet-based voice calls in the circuit switched (CS) domain of a core network (CN).
The MSC-S contains the mobility management and the call control logic without residing in the media pathway of real time communication services such as voice streams or video streams. The media pathway passes through one or more MGWs. The MGW is an element maintaining a call connection and performing switching function when required. The MGWs establish, manipulate, and release the media streams. The way the MSC-S controls the MGW is defined by the media gateway control protocol framework, also referred to as the H.248 protocol framework (MEGACO). Further control signaling occurs between a radio network controller (RNC) and the MSC-S.
Generally mobile data traffic volumes are steadily increasing. Reasons for this can be, e.g., users watching online videos. In some regions, the data traffic volumes are exceeding the volumes for CS voice data traffic already today, while all others regions show a similar trend. With the availability of the 4G radio technology (LTE) this trend can be expected to increase.
In this light, a MSC-S and MGW are supporting IP transport already today. For example, the MSC-S and the MGW of today already support packet based functionality via internet protocol (IP) for data transport between nodes in the core network. Also the CS RNCs and base station controllers (BSCs) support IP based data transport. This is known as "A-interface over IP" (AoIP) and "Iu over IP". In networks which are predominantly based on packet traffic in the packet switched (PS) domain, maintaining the CS domain for voice traffic in the CN may become complex and costly.
Accordingly, a need exists to provide efficient routing techniques for data packets of real time communication services of a call.

Routing system for transferring data packets of a call


A self-assembly structure of micro electromechanical optical switch utilizes residual stresses of three curved beams. The first curved beam pushes the base plate away from the substrate. The second curved beam lifts up the mirror slightly. Then, the third curved beam rotates the mirror vertical to the base plate and achieves self-assembly. In another embodiment, magnetic force and magnetic-activated elements are used.

In recent years, microelectromechanical Systems (MEMS) plays a great role in the development of optical systems. MEMS provides a semiconductor-like lithographic batch fabrication process which makes it easy to make micromechanical and microoptical elements integrated with control electronics on a single chip. By combining with the microoptics or waveguides, it grants the flexibility of light path design to be free-space or guided-wave. This advanced technology has been leveraged to create many crucial components for telecommunication application, such as optical switches, variable optical attenuators, tunable filters. The invention is one of the optical switches utilizing MEMS technology.
U.S. Pat. No. 6,292,600 discloses a free-rotating hinged micro-mirror switching element operated in "open" and "close" states. The micro-mirror comprises a mirror connected to the substrate by free-rotating micro-hinges. The hinges include one or more hinge pins and one or more hinge staples. Pushrods are connected at one end to the mirror and at the opposite end to the translation stage with hinge joints. And the actuated component is the scratch-drive actuator (SDA). Through applying appropriate voltage to the SDA, the SDA can be deformed or moved to a certain extent. The deformation or movement in turn causes the pushrods to act upon the mirror and rotate it to a predetermined position or angle from the substrate. Such design is able to turn the linear movement of the pushrods into rotation of the mirror and relatively reduce the entire device dimensions. However, because the degree of freedom of the mirror rotation is extremely sensitive to the optical fiber coupling efficiency, the mirror rotation angle has to be precisely controlled and encounters much difficulty.
Besides, in U.S. Pat. Nos. 6,526,198 and 6,556,741, the micro-mirror switch includes a substrate, an electrode coupled to the substrate, and a micromachined plate rotatably coupled to the substrate about a pivot axis. The micro-mirror has an orientated reflective surface mounted to the micromachined plate. An electrical source is coupled to the electrode and the micromachined plate. When voltage is applied, the electrostatic force causes the actuator move downward. The high reflection mirror surface is assembled to the actuator and perpendicular to the substrate. In order to avoid causing electrical short when the mirror moves down, a landing electrode with a buckle beam is specially used. Though the structure may provide precise movement, but each optical switch element needs additional assembly, which consumes time and a lot of work.

MEMS optical switch with self-assembly structure

Industrial Technology Research Institute


Methods, systems, and media to enhance memory leakage management by identifying a suspect allocation pattern during execution of a task, which may be indicative of memory leakage and implementing measures to protect against memory leakage based upon the suspect allocation pattern, are disclosed. More specifically, embodiments may detect a suspect allocation pattern by monitoring memory allocations and deallocations for tasks. The pattern of memory allocations and deallocations may then be analyzed to determine whether a suspect allocation pattern exists. For instance, the memory allocations and deallocations may be compared to determine whether there is an increasing net residual allocation left by the task after it has reached a quiescent runtime state. In some embodiments, a suspect allocation pattern exists if the total memory allocation for a task continues to rise after a pre-determined time period.

Computer systems are well known in the art. They have attained widespread use for providing computer power to many segments of today's modern society. Computers are available in many different forms such as a desktop, floor standing, or portable computers and include, e.g., one or more central processing units (CPUs) and associated volatile and non-volatile memory. Some computer systems also include a display, an input-output device such as a keyboard and/or a mouse, one or more storage devices such as hard disk drives, and, in many instances, a network interface adapter. One of the distinguishing characteristics of these systems is the use of a motherboard or system planar to electrically connect these components together. Examples of such computer systems are IBM's e-Server series, ThinkPad series, and Intellistation series.
The widespread use of personal computers in conjunction with networks has resulted in a reliance on the network resources such as e-business enterprises for, e.g., telecommuting, obtaining news and stock market information, trading, banking, shopping, shipping, communicating in the form of Voice Internet protocol (VoiceIP) and email, as well as other services. For many, PCs represent an essential tool for their livelihood. Thus, in today's networked world, the availability and performance of the network is as important as the availability and performance of the personal computer.
Today's e-business environment is very competitive so there is no room for failure. Servers such as the IBM pSeries help e-business enterprises remain competitive by remaining operational 24/7, 365 days a year. Because reliability is mission-critical, such servers include features to monitor for problems, features to correct or bypass minor problems on the fly, and hot swappable components to allow failed components to be replaced without powering down the server.
The problem of memory leakage, however, is not adequately addressed. Memory leakage refers to situations in which a task fails to deallocate at least some of the memory allocated to the task. For instance, when being executed, a task is allocated a portion of a heap, or other shared memory, to store variables, perform calculations, or the like. Once the task no longer needs to use the memory, the memory should be deallocated so it is available for allocation to other tasks. Memory leakage occurs when some portion of memory is not deallocated even though a task may no longer need the memory. Moreover, that same task, when executed again may be allocated more memory and may not deallocate all of that memory either, resulting in a continual leakage that can eventually consume so much of the shared memory that insufficient memory is available for other tasks.
In many instances, memory leakage remains undetected. In the latter instances, the computer system produces an "out of memory" error the next time some task needs a memory allocation and reports the error along with an identification of the task that requested the memory. The source of the memory leakage, however, is not detectable from the available information so the group of tasks must be restarted and, depending upon how critical the tasks are on the operation of the computer system, the entire computer system may need to be powered down and rebooted.
Further, memory leakage may occur only under specific circumstances that result from a combination of tasks being executed simultaneously. Thus, debugging the error is difficult post-mortem.
Many servers forward the "out of memory" error to a technical service provider to resolve the error. The technical service provider must re-create the circumstances to reproduce the memory leakage and/or review thousands or hundreds of thousands of lines of code to find the code responsible for the memory leakage. In many instances, one or more highly experienced software "trouble-shooters" may work on the problem for months before finding a solution, while the customer continues to endure the problem.
Restarting the application or rebooting the computer system, temporarily fixes the memory leakage condition. However, powering down and rebooting a network server significantly impacts the availability and reliability of the server, which is a very undesirable effect when availability and reliability are key features for distinguishing the server from a multitude of available servers on the market. For instance, many servers take hours or even days to return to service once they are powered down. Further, the memory leakage condition is not corrected, the condition is just delayed until the next time that the circumstances facilitate a memory leakage by the task.
Therefore, there is a need for methods, systems, and media to enhance memory leakage management by identifying attributes of a task potentially related to memory leakage and implementing measures to protect against memory leakage based upon the attributes identified. In some embodiments, upon detecting a memory leakage associated with a task, the embodiments may generate a signal adapted to terminate and restart the task or to request that the task be terminated and restarted. When the task restarts, memory usage by the task is reset, freeing up the leaked memory.

International Business Machines Corporation


A load control system for controlling a plurality of lighting loads located in a space may be configured to track the location of one or more tracked devices. The load control system may comprise a system controller, lighting control devices, e.g., for controlling a plurality of lighting loads, and tracked devices. The tracked devices may each transmit beacon messages. The lighting control devices may receive the beacon message. The lighting control devices may measure a communication quality metric of each of the beacon messages, and process the measured communication quality metrics received over a period of time to determine a processed communication quality metric for the tracked device. The lighting control devices may transmit tracking data to the system controller. The system controller may determine a location of the tracked device. For example, the system controller may determine the location of the tracked device via trilateration.

A user environment, such as a residence or an office building for example, may be configured using various types of load control systems. A lighting control system may be used to control the lighting loads in the user environment. A motorized window treatment control system may be used to control the natural light provided to the user environment. A heating, ventilation, and air conditioning (HVAC) system may be used to control the temperature in the user environment.
Each load control system may include various control devices, including control-source devices and control-target devices. The control-target devices may receive messages (e.g., digital messages), which may include commands (e.g., control instructions, such as load control instructions), for controlling an electrical load from one or more of the control-source devices. The control-target devices may be capable of controlling an electrical load. The control-source devices may be capable of controlling the electrical load via the control-target device. Examples of control-target devices may include lighting control devices (e.g., a dimmer switch, an electronic switch, a ballast, or a light-emitting diode (LED) driver), a motorized window treatment a temperature control device (e.g., a thermostat), an AC plug-in load control device, and/or the like. Examples of control source devices may include remote control devices, occupancy sensors, daylight sensors, temperature sensors, and/or the like.
Although control-source devices may be capable of controlling a control-target device, a control-source device may not be capable of controlling a control-target device, based on a user location and/or a mobile device. For example, a control-source device may not be capable of setting a control-target device to a lighting intensity, based on a user and/or mobile device located within the load control system. This may be desirable, for example, for users located in an office that may desire to have a lighting intensity, temperature level, and/or natural light provided at a predefined level.

Real time locating system having lighting control devices


A packaging substrate includes: a dielectric layer unit having top and bottom surfaces; a positioning pad embedded in the bottom surface of the dielectric layer unit; at least a passive element having a plurality of electrode pads disposed on upper and lower surfaces thereof, the passive element being embedded in the dielectric layer unit and corresponding to the positioning pad; a first circuit layer disposed on the top surface of the dielectric layer unit, the first circuit layer having first conductive vias electrically connected to the electrode pads disposed on the upper surface of the passive element; and a second circuit layer disposed on the bottom surface of the dielectric layer unit, the second circuit layer having second conductive vias electrically connected to the electrode pads disposed on the lower surface of the passive element. Through the embedding of the passive element, the overall structure may have a reduced height.

1. Field of the Invention
This invention relates to packaging substrates and methods of fabricating the same, and, more particularly, to a packaging substrate having a passive element and a method of fabricating the same.
2. Description of Related Art
With the rapid development of semiconductor package technology, passive elements are in increasing demands. Passive elements do not affect the basic characteristics of signal, but only allow the signals to pass therethrough. Passive elements include capacitors, resistors and inductors. Compared to active elements, the passive elements have their resistances unchanged even when voltages or currents change, because the passive elements do not participate in electron exercises.
Any product that is driven by electricity needs passive elements that provide electrical loop controlling functions. Such applications include 3C and other industrial fields. Please refer to FIG. 1, which is a cross-sectional diagram of a packaging substrate having a passive element according to the prior art. A passive element 12 is disposed on conductive pads 11 on a substrate 10 by means of solder bumps 13.
With the development of technology, electronic devices are designed to meet the low-profile and compact-size requirements. However, a package structure of the prior art, in which the passive element 12 is disposed on the substrate 10, has an increased height, and is adverse in the thinning design for the electronic devices. Since the passive element 12 is disposed on an external surface of the substrate 10, a signal transmission route between an interlayer circuit and a passive element of the substrate 10 is very long, which results in the loss of electricity and electrical functionality. Also, the surface of the substrate 10 is occupied by a circuit layout, so an area within which passive elements may be disposed is very limited. Therefore, only a small number of passive elements may be disposed on the substrate 10. As the number of passive elements increases, the area reduction of the circuit layout is inevitable.
Therefore, how to avoid the drawbacks of the packaging substrate having a passive element of the prior art is becoming one of the popular issues in the art.

Method of fabricating packaging substrate having a passive element embedded therein


Embodiments of the present invention provide a method for generating a label forwarding table for a non-destination router on a ring topology. Embodiments of the present invention further provide an apparatus for generating a label forwarding table for a non-destination router on a ring topology and a method and system for generating two label switching paths LSPs of different ring directions on a ring topology. Technical solutions provided by the embodiments of the present invention are based on a clockwise label forwarding table and a counterclockwise label forwarding table that are generated for each non-destination router on the ring topology. When it is found that traffic cannot be forwarded to a destination router by using one of the two label forwarding tables, the non-destination router performs traffic switching and uses the other label forwarding table to forward the traffic.

More and more telecom operators around the world are gradually migrating originally scattered and incompatible networks that adopt different technologies to unified network architecture based on the Internet protocol (IP) or multi-protocol label switching (MPLS) technology. With advantages such as being flexible and simple, topology-independent and connection-oriented, an IP/MPLS technical system is becoming a major service bearing manner adopted by the telecom operators in a network.
The IP/MPLS technical system mainly includes two parts, namely, a control layer and a forwarding layer. The control layer is mainly responsible for discovering an end-to-end route and establishing a path in a network, and the forwarding layer is mainly responsible for addressing and distributing of packets. Main protocols defined at the control layer include the open shortest path first (OSPF) protocol, the intermediate system to intermediate system (IS-IS) protocol, the label distribution protocol (LDP), the resource reservation protocol (RSVP), and so on. Main specifications defined at the forwarding layer include IP, MPLS and so on.
The MPLS uses a short label of a fixed length to an encapsulate network layer packet. Two important concepts in the MPLS are forwarding equivalence class (FEC) and label.
The MPLS is actually a class-based forwarding technology that classifies packets with a same forwarding processing manner (having a same destination, using a same forwarding path, and having a same service level) into one class, which is referred to as an FEC. Generally speaking, classification of a packet into an FEC is in accordance with its network layer destination address. Packets belonging to a same FEC get completely the same processing in an MPLS network.
A label is a short identifier that is of a fixed length and has a local meaning, and is used to identify an FEC. When packets arrive at ingress of the MPLS network, they are classified into different FECs according to a certain rule, and according to a FEC to which a packet belongs, a corresponding label is encapsulated in the packet. Therefore, in the network, the packet may be forwarded according to the label.
LDP is an important protocol at the control layer of the IP/MPLS architecture, and defines a mechanism and method for establishing a point-to-point LSP between two nodes along a shortest path. At present, the following situation may exist in an LSP established on a ring topology according to LDP: if a link fault occurs on the ring topology, packets are discarded, and such a packet loss process does not stop until a completely new LSP is established. The entire packet loss process generally lasts for a few seconds, which is unacceptable for a mobile voice service.

Method, apparatus and system for generating label forwarding table on ring topology