Curl caused in a paper sheet in a fixing device during fixing of a toner image is removed while smoothly changing a direction of feed of the paper toward a plurality of paired discharge rollers in the fixing device. Anti-curl ribs, each having a rounded face that projects to pass through a plane connecting a contact point between a heating roller and a pressing roller and a contact point between the respective discharge rollers are arranged between the heating roller and the pressing roller and the plurality of paired discharge rollers in a fixing unit. Further, a first set of paired discharge rollers and a fourth set of paired discharge rollers are arranged respectively in correspondence with the anti-curl ribs and two of the anti-curl ribs are provided in correspondence with the side portions of the paper. Lastly, bent guide films are arranged on both sides of second guide ribs that correspond to the first and fourth sets of paired discharge rollers to facilitate paper feed.

1. Field of Invention
The invention relates to a fixing device in an image forming apparatus for fixing a toner image transcribed on paper by heating paper on which an image formed by supplying a toner in accordance with an electrostatic latent image formed on a photosensitive drum in a developing device, is transcribed. Particularly, the invention relates to a fixing device capable of removing curl caused in the paper in the fixing device in fixing a toner image by smoothly changing a feed direction of the paper toward a discharge roller in a fixing device.
2. Description of Related Art
There have conventionally been proposed various image forming devices, such as a laser printer or the like, adopting a so-called electronic photographing system. For example, an image forming device having a paper feeding device, a laser scanning device, a toner supplying device, a developing device, a fixing device and the like in gross classification, is disclosed in the specification and the drawings of Japanese Printed Patent Document No. 9-319201. According to such an image forming device, an electrostatic latent image is formed on the surface of a photosensitive drum in the developing device in accordance with image data provided by the laser scanning device, a toner image is formed on the photosensitive drum by supplying a toner in accordance with the electrostatic latent image from the toner supplying device, the toner image is transcribed by the cooperation of a transcribing roller and the photosensitive drum on a paper transferred from the paper feeding device into the developing device and thereafter, the toner image is fixed by heating the paper by the fixing device.
According to the fixing device, paper is heated by a heating roller in fixing the toner image. As a result, curl is caused in the paper after fixing processing and therefore, various curl removing means are provided to remove the curl caused in the paper. According to the curl removing means, generally, a method of removing curl is by winding the paper in a direction reverse to the direction of curl, caused during fixing, has been adopted.
For example, it is a general method that in a fixing device, a discharge roller and a pressing roller that is brought into press contact with the heating roller are arranged on the downstream side of a heating roller in the paper feed direction, two auxiliary casters are brought into press contact with the discharge roller, and a reverse curl is provided to the paper on the basis of cooperation between the discharge roller and the respective auxiliary casters thereby removing the curl of the paper.
However, according to the conventional fixing device, in structuring the means for removing curl from the paper, the two auxiliary casters which are brought into press contact with the discharge roller are needed and further, accessory parts, such as a spring, for bringing the respective auxiliary casters into press contact with the discharge roller are also needed. As a result, the cost of the fixing device is increased and the total cost of the image forming apparatus is increased.

Anti-curl feature in a fixing device for an image forming apparatus


Disclosed is a network game system in which a time lag is adjusted, using game terminal type information such as its ID number. A network game server comprises a lag adjusting program and a database to be referenced to execute the lag adjusting program. On the network, data from game terminals is transmitted in packets to the network game server where concentrated management is made of all packet data as user information. Different transmission time lags predetermined for the product types of the game terminals that are expected to connect to the server are stored into the database beforehand. When the server receives packet data from a terminal device having an EUI-64 identifier, the appropriate transmission time lag is read, based on the identifying information.

1. Field of the Invention
The present invention relates to a network game system including a plurality of network game terminals each having different throughput and a network game server which stores network game applications and processes packet data transmitted from the network game terminals, the network game terminals and the network game server being connected via a network, and a network game server and a network game terminal that can be used to be constituents of such a system.
2. Description of the Related Art
A real-time network game system has heretofore been known in which a server has game management software and terminals have game software. When the users of the terminals play a game by operating game software on their terminals, data is generated on each terminal, and, out of the data, at least data required for other users to play the game is transmitted to the server. Other users having access to the server read the data transmitted to the server. Based on the data thus read, the remote users play the game together concurrently, using the game software stored in their terminals. This system is disclosed in JP-A No. 6700/1997. As another network game system, a game system nursing a virtual living thing via a network is disclosed in JP-A No. 296271/2000. Client terminals access a server via a computer network and nurse a virtual living thing in a virtual space provided by the server.
Such gaming via a network enables a great number of people to play a game simultaneously and information for all users concentrates at a game server on the network. For a network game for which the real-time processing ability of the machine used to participate in it is essential requirement, difference in throughput across the participants' game terminals brings about unfairness across the game players. For example, when playing a kind of fight game across on-line participants, a game player using a machine with a higher CPU processing speed would always be advantageous in getting points of the game.
FIG. 4 is a timing chart representing the operations of two game terminals over time and their CPUs differ in processing speed. A game terminal 10 has a CPU whose processing speed is higher than the CPU of a game terminal 20. The timing chart represents the operation progress in a cycle; the game terminals 10 and 20 process data received from the server, return the result of processing the data to the server, and receive the result of the server processing of the data from the server. Time t1 in which the game terminal 10 processed the data is shorter than time t2 in which the game terminal 20 processed the corresponding data. Therefore, even if it takes equal time to transmit data from the game terminals 10 and 20 to the server, the server starts to process the data received from the game terminal 10 earlier. Accordingly, time difference between the operations of the two game terminals 10 and 20 gradually increases until they receive the result of the server processing of the data from the server.
As means for eliminating the unfairness by throughput difference across game terminals, an idea was proposed that the server be provided with a function of adjusting a lag when transmitting packet data to the participants' game terminals, considering the processing speed of the components such as CPU of the game terminals. That is, the game server initially measures the throughput of a game terminal used by each player and stores data transmission time lags according to the throughput of each game terminal in its database. When the server transmits packet data to each game terminal, it keeps the data in a buffer for a time equaling the time lag set per terminal. In this way, the server can adjust the time lag of data transmission.
With the increasing number of players participating in a network game, however, the following problem arose. The server need to know the processing speeds of all game terminals connected to the network and it takes more time to measure them. Moreover, creating a database for determining a time lag for each terminal takes time.
Most of the game terminals are products supplied from only a limited number of manufactures thereof and the number of types thereof is not so many. Notwithstanding, the server calculates and stores the time lags for all game terminals. This was inefficient. Moreover, each time a game terminal transmits data to the server, access to the database and reading the adjustment time lag set for the terminal must be performed and the time consumed for this is undesirable.
Furthermore, an extensive network requires memory space expansion for creating the database, which posed a problem of great costs of database provision.

Network game system, network game server, and network game terminal


A circuit arrangement for selective powering of distributed loads (D1-D7, 220-226, 213a-213e) is provided, comprising a plurality of load segments (10, 20, 30, 40, 50, 60, 70), each being electrically connected to at least one supply terminal al for receiving a variable voltage, wherein each load segment (10, 20, 30, 40, 50, 60, 70) comprises at least a load unit (D1-D7, 220-226, 213a-213e) and a proximity sensor unit (11), coupled with said load unit and comprising at least a reactive device (L1-L7, L1a-L7a, C1-C7, C1a-C7a, 214a-214e, 215d) having a reactance, said reactance depending on the proximity of a detection object (100, 102). In order to provide a simple and accurate way for user interactive powering of loads (D1-D7, 220-226, 213a-213e), during operation an operating voltage is provided to at least one load unit (D1-D7, 220-226, 213a-213e), depending on the reactance of at least one reactive device (L1-L7, L1a-L7a, C1-C7, C1a-C7a, 214a-214e, 215d) of said load segments (10, 20, 30, 40, 50, 60, 70), so that said operating voltage depends on the proximity of said detection object (100, 102).

With the increasing importance of LED-based lighting, LEDs already have a significant role in the area of decorative lighting. The low power consumption and long lifetime of LEDs make them a highly favorable choice for various applications. Moreover, LEDs having various colors are known in the art. It is also known, for instance, to combine red, green and blue LEDs to create the impression of a virtually unlimited variety of colors.
Especially when controlling numerous LEDs to create certain distributed effects, like LEDs on a string of lights or on a lighting surface, the cost of control electronics has to be taken into account. While relatively cheap LEDs are available today, a need exists to control the LED arrangement by means of simple and cheap control elements.
For decorative and/or user interactive LEDs and other kinds of loads, it is often desirable to detect the place where a certain effect is desired. For instance, in a string of
LEDs, one can think of a user indicating one or several LEDs to be activated, which indication is detected by some kind of sensor. After said detection, a driver or the like has to deliver the energy to this specific location. For many applications, resolution and accuracy requirements put on the detection are quite high, in order to avoid a mismatch between desired and realized effect.
For optical effects like the ones created with LEDs, the control may be based on cameras and a dedicated picture processing algorithm. In this case, good alignment can be expected. For other, non-optical effects, the determination of the actual effect position is quite complicated, so that there is hardly any possibility of applying a feedback signal to the controller. In addition to these control problems, the driver has to offer a high resolution in order to reproduce most of the desired effects at the specific location.
However, the detection and control devices known in the art are quite complicated, especially when a large area and/or many devices have to be controlled. This in turn leads to relatively high costs.
It is therefore an object of the present invention to provide cost-efficient and accurate means for user interactive powering of loads.

Circuit arrangement for selective powering of distributed loads


A green emitting lanthanide aluminate phosphors activated with manganese and alkali halide, and blends thereof, for plasma display panels (PDP) and methods for their preparation are provided. The phosphor has an empirical formula:Ln2-x-yB22O36:Mnx.Ay wherein Ln is a lanthanide metal selected from the group consisting of: La, Y, Gd, Tb, and a combination thereof, wherein La is: 0.57≦La≦1.782; Y is: 0≦Y≦0.19; Gd is: 0.198≦Gd≦0.95; and Tb is: 0≦Tb≦0.19; A is selected from the group consisting of: Li, Na, K and a combination thereof; B is selected from the group consisting of: Al and a combination of Al and Ga; x is 0.01≦x≦0.1; and y is 0.01≦y≦0.1. These phosphors have a band emission in green region, peaking at 515 nm when excited by 147 and 173 nm radiation from Xenon gas mixture of various compositions, a uniform particle size distribution (0.01 to 10 microns) appropriate for thin phosphor screens required for a variety of flat panel display and lamp applications and exhibit high brightness, good color saturation, good stability and shorter persistence under VUV excitation.

1. Field of the Invention
The present invention relates to the preparation and growth of small size particles Mn2+ and alkali halide doped lanthanide aluminate phosphor by solid sate and sol-gel methods. More specifically, the present invention provides stable green emitting Mn2+ and alkali halide doped lanthanide aluminate phosphor and process by thermally decomposing salts of lanthanum, gadolinium, terbium, manganese, alkali halide and alumina or sol-gel powders. To enhance the brightness, phosphor of present invention is blended with other terbium activated green emitting phosphors such as lanthanide borate, lanthanide phosphate or cerium magnesium aluminate.
2. Description of the Related Art
The plasma display panel (PDP) as a medium of large format (60+″) television (TV), particularly high definition TVs (HDTV's) is gaining attention over cathode ray tube (CRT) based TVs due to its' high performance and scalability. Although, CRT works with less power and having better picture quality, it has size limitation. Larger screens (CRT) of diagonal size more than 40 inches have larger depth and very heavy. Conversely, diagonal size of PDP is growing day by day, as there is no problem with depth and weight.
The structure of a PDP, which is known in the art, is described in FIGS. 1a and 1b. FIGS. 1a and 1b represents the cross section of an AC PDP. The plasma display has of two large area glass substrates 11, 16. Front plate 11 is made with sustain electrode 12 and scanning electrode 13, covered with thick dielectric layer 14 and a thin protection layer (MgO) 15. Back plate 16 is made with address electrodes 17, reflective layer 18, barrier ribs 19 and red phosphor 20R (Y,Gd)BO3:Eu2+, green phosphor 20G ZnSiO4:Mn2+ (P1) or the blend of ZnSiO4:Mn2+ and Y,GdBO3:Tb3+, and blue phosphor 20B BaMgAl10O17:Eu2+ coated by screen printing or ink jet process. Both the glass plates are frit sealed together and filed the space 21 with Xe, Ne gas mixture. When voltage is applied, a discharge is developed in the space 21 producing Vacuum UV (147 and 173 nm). When phosphors 20RGB are excited by VUV photons, they emit respective visible radiations viewed through the transparent front plate as an image 22.
The luminous efficiency of a PDP depends upon various factors including materials such as phosphors, gas mixture, dielectric layer, reflective layer, black matrix, electrodes, cell dimension and shape, nature, size and shape of electrodes, address waveforms, operating voltages, etc. The performance and lifetime of a PDP is strongly related to the nature of phosphors and their resistance to energetic discharge ions, electrons, and solarization from VUV arising from Xe/Ne gas discharge. Compared to standard emissive display such as CRTs (5-6 lm/W), the efficiency of a PDP is low (1-2 lm/W).
To improve the overall efficiency of PDPs, considerable developments related to materials, design, process and electronics are under way. Efforts are also being made to develop new phosphors as well as to improve existing phosphors. Due to vacuum UV specific wavelengths available from Xe discharge (147 nm and 173 nm), only a limited number of lamp phosphors are suitable for PDP applications. In addition to high luminous efficiency, PDP phosphors should have longer life or stability, required persistence, suitable color coordinates, color temperature, and color saturation.
The main application of large area plasma displays will be HDTV and high information content presentation. HDTV and similar type of display devices should have phosphors with low dielectric constant, required decay time, high resolution and high brightness for high performance. Screens coated in a close rib structure or closed cell structure with small particles exhibit higher packing density and also need lesser binder content.
Short time persistence value, which is defined as being 10% of the initial brightness, should be between 4 and 9 ms. Long time persistence, is another concern in selecting a phosphor, and should be less than 0.25% of initial brightness after 2 to 10 seconds. The three phosphors (red, green and blue) currently used in PDP's have different dielectric constants and particle morphology. Due to their physical nature, all of the three phosphors need different rheology of phosphor paste as well as different screening processes. In PDP applications these phosphors exhibit different electrical characteristics in a finished panel. This results in compromises in the performance of the display.
HDTV and similar type of devices should have high resolution and higher brightness for better performance. This can be achieved only with thin phosphor screens formed with very small phosphor particles (1-5 microns) in a close rib structure particularly in the case of PDP's. Screens with small particles have a higher packing density and also require lower binder content. Manganese activated zinc silicate phosphor with or without terbium activated yttrium gadolinium borate is currently used in plasma display panels (PDP) as a green emitting component due to its availability and high quantum efficiency.
The higher dielectric constant of zinc silicate phosphor (P1) is of particular concern as it charges more than its' blue and red counterparts and this results in a higher sustainer voltage. The charging effect on P1 phosphor is higher in presence of higher Xe concentrations (>5%). Higher Xe concentration is need in a PDP to increase the brightness levels. When compared with red and blue emitting phosphors, zinc silicate phosphor (U.S. Pat. No. 5,985,176) also exhibits longer persistence, lower dielectric constant, negative discharge and faster saturation with the VUV flux. Another suitable green candidate, Tb activated yttrium gadolinium borate, which shows lower color purity is described in U.S. Pat. No. 6,004,481. As a trade off, PDP industry is adopting the blend of P1 and Tb activated rare earth borate phosphors. The negative discharge of zinc silicate phosphor has become positive in a blend of zinc silicate phosphor (50%) and rare earth borate based phosphor (50%) in a plasma display panel as described in U.S. Pat. No. 6,753,645 B2. Efforts are being made to develop new phosphors to satisfying all requirements and replace existing Mn activated zinc silicate phosphor or the blend of silicate and borate.
Some other phosphor candidates based on alkali halide aluminates have being mentioned in Phosphor Handbook. U.S. Pat. Nos. 4,085,351, 5,868,963 and 6,423,248 B1 disclose the application of manganese activated aluminate phosphor with either of calcium, strontium, barium, magnesium or zinc in a gaseous discharge light-emitting element. Preparation of Manganese activated lanthanum, yttrium gadolinium aluminate green emitting phosphor excited by VUV ray is described in U.S. Pat. No. 6,805,814. European Patent No. EP 0 908 502 A1 teaches the preparation of barium or strontium magnesium aluminate by firing respective oxides or carbonate in presence of flux (AlF3) at 1450° C. for 48 hours (total time). International Patent Application No. WO 98/37165 describes a method of making oxygen containing phosphor powder, which includes alkaline earth aluminates by spray techniques. European Patent No. EP 1 359 205 A1 describes the method of preparation of various green emitting phosphors has La, Mg, Zn aluminates with Tb, Mn as activators.
Green emitting Mn and alkali metal activated lanthanum aluminate phosphors have been described in the commonly owned, co-pending U.S. Patent Application Publication No. 2005/0194570 A1, filed Mar. 2, 2004, entitled "Green Emitting Phosphor Material and Plasma Display Panel Using the Same," the contents of which are incorporated herein by reference.
Other related aspects to such phosphors are described in U.S. Pat. Nos. 4,150,321; 5,989,455; and 6,222,312 B1; European Patent No. 0 697 453 A1; International Patent No. WO 98/37165 by Hampden-Smith Mark, et al.
Further aspects to such phosphors are described in publications entitled (1) "Fluorescence in β-Al2O3-like materials of K, Ba, La activated with Eu2+ and Mn2+" by M. Tamatani, Jap. J. Applied Physics, Vol. 13, No. 6, June 1974 pp 950-956; (2) "The behavior of phosphors with aluminate host lattices" by J. L. Sommerdijk and A. L. N. Stevels, Philips Tech. Review Vol. 37, No. 9/10, 1977 pp 221-233; and (3) "Principal phosphor materials and their optical properties" by M. Tamatani in "Phosphor Handbook" edited by S. Shionoya and W. M. Yen, CRC Press (1999) pp. 153-176 and "Tb3+ activated green phosphors for plasma display panel applications" by R. P. Rao, J. Electrochemical Society Vol. 150 (2003) pp H165-171.
However, none of these patents and publications describe a green emitting Mn and alkali metal activated lanthanide aluminate phosphor according to the present invention.

Stable green phosphor and plasma display panel using the same


A mold having a pattern of a concavo-convex surface including protrusion and recess is prepared and the pattern is transferred to a resist layer formed on a substrate by an imprinting method. The side surface of a protrusion of the transferred resist pattern is then etched so that the protrusion has a width narrower than a width of the corresponding recess formed to the mold. This resist pattern forming method is preferably applicable to a magnetic recording medium manufacturing method and a magnetic head manufacturing method.

1. Field of the Invention
The present invention relates to a resist pattern forming (formation) method utilizing an imprinting method, and also relates to a magnetic recording medium manufacturing method and a magnetic head manufacturing method, both utilizing the method of forming the resist pattern mentioned above.
2. Related Art
In a method of manufacturing a semiconductor element or recording medium, for example, there is known an optical lithography method for forming a fine resist pattern to a resist layer formed on a substrate surface. In the resist pattern forming method utilizing this optical lithography method, a light is irradiated on the resist layer formed on the substrate surface (for example, a layer formed by applying a resist material, in thin film form, such as a resin which is reacted with light to be hardened) to thereby form a concavo-convex pattern, on the resist layer, which is thereafter developed, thus forming the resist pattern.
Furthermore, in recent years, in order to satisfy requirement of high density of the semiconductor element and increasing of recording capacity of the recording medium, there has been developed an electron-beam lithography technology capable of forming a resist pattern of nano-meter size by irradiating an electron beam in place of the light.
In such electron beam lithography technology, however, the resist pattern formation requires much time, which may provide inconvenience for mass-production, and moreover, an electron-beam lithograph device is expensive, leading to cost-up of a product.
Furthermore, in these days, another resist pattern forming method has been proposed as fine resist pattern forming method (as 'imprinting method'), for example, as disclosed in "Imprint of sub-25 nm vias and trenches in polymers" (Applied Physics Letters), by Stephen Y. Chou, Nov. 20, 1995, Vol. 67, No. 21, Pages 3114–3116, in which a concavo-convex portion including protrusion and recess of nano-meter size formed to a mold is pressed against the substrate surface to thereby transfer the shape of such concavo-convex portion to thereby form the resist pattern of nano-meter size.
This resist pattern forming method includes the following steps or processes, for example, such as shown in FIGS. 12A to 12D.
With reference to these figures, a mold (which may be called 'stamper') 21, as shown in FIG. 12B, having inverted patterns having protrusion 22 and recess 23 to be transferred of a concavo-convex shape and a substrate 11 are heated to a temperature more than a transition temperature of glass of a resist material forming the resist layer 12 and, thereafter, such mold 21 is pressed against the resist layer 12 formed on the surface of the substrate 11 as shown in FIG. 12A.
Next, under the state that the mold 21 is pressed against the resist layer 12, it is cooled to a temperature less than the transition temperature of the glass used as the resist material and then separated from the resist layer 12, whereby, as shown in FIG. 12C, the concavo-convex pattern (including protrusion 15 and recess 14) is transferred to the resist layer 12.
Further, in such processes, a resist material, which is not removed to the other portions at the mold pressing time, remains in the recess 14 of the resist pattern formed on the substrate 11, which is called herein later as 'resist remaining layer' denoted by reference numeral '3'. For this reason, as shown in FIG. 12D, this resist remaining layer 3 is thereafter removed by, for example, an etching treatment, to thereby expose a substrate surface 16 at this recess 14.
Further, although not directly relating to such imprint method, prior art of, for example, Japanese Patent Laid-open (KOKAI) Publication No. 2000-181082 or No. 2003-231608 discloses a patterning technology as 'semiconductor manufacturing method' in which a photoresist (or photo-resist) subjected to pattern exposure is treated by isotopic-etching using ozone to thereby carry out a fine patterning more than that performed by the pattern exposure.
In consideration of countermeasure to the requirement for achieving the high density of the semiconductor element and increasing the recording capacity of the recording medium, in order to make the recording density of the recording medium high, at the time of manufacturing a discrete-track-type magnetic recording medium (called hereunder 'discrete track medium'), which has been attracted as magnetic recording medium for future generation, it is necessary to make small, by some extent, a track pitch of a data recording track formed with the fine pattern of a layer of the magnetic material (i.e., magnetic layer). Accordingly, it is necessary to reduce, by some extent, the width of a groove between the tracks formed from the magnetic layer, and this groove corresponds to a non-magnetic portion for reducing magnetic influence to the adjacent recording tacks at the time of reading the recorded data.
In this time, in a case where the resist pattern 60 formed by the resist pattern forming method of the characters mentioned above is used as a mask, and as shown in FIG. 13, a metal mask layer 61 and a magnetic layer 62 are etched to thereby form the groove, i.e., non-magnetic portion, 63, the width of the groove to be etched is narrowed, as shown with a broken line in FIG. 13, in the direction separating from the resist pattern 60 (i.e., on the lower side in FIG. 13). For this reason, in a case where the width w7 at the protrusion of the resist pattern 60 is too widened without changing the pitch for forming the data recording track 65, there may cause a fear that it may become difficult to form the groove 63 having a depth reaching the substrate 64.
Accordingly, in order to form a resist pattern having a narrow width of the protrusion, i.e., w7 in FIG. 13, it will be necessary to press the resist layer 12 formed on the surface of the substrate 11 so as to transfer the concavo-convex shape including protrusion and recess of a mold 21a having a narrow width of a recess 23a, (i.e., in other words, a wide width of the protrusion 22a) shown in FIG. 14a.
However, as shown in FIG. 14A, it is more difficult to form the resist pattern having the narrow width of the protrusion by pressing mold 21a, against the resist layer, having the recess 23a having a narrow width than to form the resist pattern having the protrusion having a wide width by pressing the mold having the wide width of a recess 23b shown in FIG. 14B. That is, in the case of using the mold 21a having the narrow recess 23a, it contacts the resist layer 12 at a wide area, which requires a high load to the mold 21a for pressing the resist layer 12, and in addition, the formed resist pattern may be ready peeled at the time of separating the mold 21a from the resist layer 12. Such adverse phenomenon will become remarkable in a case of using a mold having a line-and-space pattern in which recesses and protrusions are periodically arranged as shown in FIGS. 14A and 14B.

Resist pattern forming method, magnetic recording medium manufacturing method and magnetic head manufacturing method


Continously variable-length antenna, operating in a wide frequency range that's simple, lightweight and reliable, and can be constructed by using a metal case-resided, coiled steel band spring returnable metal tape for the actual antenna, and pulling or releasing it by a thin insulating line. A strong, lightweight insulating tube, guiding the metal tape in its mechanical excursions, also provides for weatherproof construction. Remote controlling and an extremely wide range of antenna lengths can easily be realized.

This invention relates to an easily realizable, remotely adjustable length of an antenna element (monopole) in order to extend the operating frequency range.
The proper length of an antenna monopole (single antenna element) or dipole (two antenna elements or monopoles), or any other type of antenna consisting of more monopoles, for a given feeding point (radio frequency signal connection point) and antenna impedance, is inversely proportional to the operating frequency. Proper operation of the same antenna at different frequencies or frequency bands is achieved with the length of the antenna being variable and preferably remotely adjustable for the current operating frequency. If the required operating frequency band is wide, the antenna length has to vary in a wide range from very short to very long. There are also other important factors, which any long (few tens of feet) antenna, meant for outside free air operation, should fulfill: reliable mechanical and electrical operation in any position, weatherproof and lightweight construction, etc.
One of the solutions for continuously varying the length of an antenna may be based on a telescope principle. Antennas utilizing this type of mechanism are widely found in automobiles, where the telescope feature is used to erect or retract the antenna manually or remotely. Such an antenna would be too heavy for having tens of feet in maximum length, with a complicated and bulky length-adjusting high-power mechanism. Since the telescope antenna consists of several moving sections, there would always be a potential problem of having poor electrical contact between the sections; furthermore, there is an inherent problem with the telescope principle: the minimum length of the antenna cannot be less than the length of its longest section.
Using a metal tape as the actual antenna, extended from a power returnable metal tape mechanism, would be a better solution. Length variation is easily achieved by just pulling out or releasing back the metal tape with a thin insulating line in a strong, lightweight insulating tube.


A Rhodobacter species and variants thereof are provided for odor remediation of anaerobic livestock waste lagoons. Also provided are vector systems and genetically reconstituted Rhodobacter PS9 cells, and related methods for biomass production in anaerobic livestock waste lagoons.

This invention relates generally to the isolation and use of bacterial strains for odor remediation and fermentation in anaerobic livestock waste lagoons. In particular, the invention relates to the isolation of a biologically pure culture of a Rhodobacter PS9 (xe2x80x9cRPS9xe2x80x9d) bacterial strain and methods of using the bacterial strain to reduce the concentration of malodorous volatile organic compounds in anaerobic livestock waste lagoons and for biomass production from genetically reconstituted RPS9 cells.
Several publications are referenced herein. Full citations for these publications are provided below. The disclosures of these publications are hereby incorporated herein by reference in their entirety, unless otherwise noted.
Livestock waste lagoons are large reservoirs used for the storage and treatment of livestock waste and runoff. In order to operate efficiently, the waste must be loaded at an appropriate rate and maintained at a minimum volume. Such lagoons may be aerobic, anaerobic or facultative. While aerobic waste lagoons control sludge and odor better than anaerobic lagoons, they require the use of mechanical aerators to ensure adequate oxygen. In contrast, anaerobic lagoons can treat high waste load rates, do not require aeration, and thus operate at a much lower cost.
Anaerobic lagoons are often associated with noxious odors causing environmental problems associated with their use. In addition, the proximity of waste lagoons to populated areas exposes waste lagoon operators to nuisance lawsuits and potential liability. To help reduce problems associated with noxious odors, a two-stage anaerobic lagoon may be employed, wherein treated waste from a first cell is transferred to a second adjacent cell. However, operation of a two-stage lagoon is expensive. The main source of odors associated with anaerobic a waste lagoons results from the anaerobic digestion of complex, volatile, organic compounds resulting in the production of malodorous volatile organic and inorganic compounds.
U.S. Pat. No. 5,861,096 is directed to reducing odors from wastewater by chemical treatment. According to the patent, the most common source of odors in wastewater is reduced sulfur compounds resulting from anaerobic bacterial decomposition of biodegradable organic matter in the presence of sulfates. The patent refers to spraying an aqueous solution of a chlorine compound over the surface of a wastewater lagoon to react with the sulfides emanating from the surface. The spray may be provided through spray nozzles using a pipe distribution system and must cover at least 1,000 square feet.
U.S. Pat. No. 5,744,041 is directed to adding undefined cultures of anaerobic bacteria to wastewater to reduce the biological oxygen demand (BOD) of the wastewater. A portion of the treated wastewater with a reduced BOD is mixed with aerobic bacteria to form a liquor comprising water and aerobic organisms. The liquor is subjected to microzone treatment to remove a portion of the aerobic microorganisms. xe2x80x9cGenetically engineeredxe2x80x9d or xe2x80x9cgenetically reconstitutedxe2x80x9d organisms are often used for large-scale biomass production. Typically, a gene encoding a protein of interest is cloned into a bacteria using a vector system. The bacteria are grown in a large-scale fermentation process and induced to express the protein of interest which is then isolated from the bacterial cells. Significant costs are associated with establishing and maintaining particular bacterial growth conditions, including providing the appropriate growth media, temperature, pH, and oxygen level. Most plasmid vector systems rely upon use of antibiotic selection genes to maintain the presence of the vector in the cell. Furthermore, vector systems typically require the addition of exogenous compounds to induce expression of genes under the control of promoter sequences.
What is needed are new methods of reducing the odors associated with livestock waste lagoons in a reproducible, cost-effective and environmentally friendly manner. Systems and methods for large-scale biomass production are also needed that rely on naturally-occurring conditions and do not require the addition of antibiotics or other exogenous compounds.
This invention provides a newly isolated Rhodobacter PS9 strain and methods of using such strain to reduce the odor associated with livestock waste lagoons. Also provided herein are methods of using genetically reconstituted Rhodobacter PS9 cells for large-scale biomass/enzyme production.
The present inventors have identified RPS9 as the major photosynthetic bacterium in certain anaerobic livestock waste lagoons. In these photosynthetic lagoons, this bacterium constitutes 40 to 60% of the total microbial populations. The present invention provides a newly isolated photosynthetic bacterial strain, RPS9. Cultures of RPS9 are used, according to a preferred embodiment of the invention, to inoculate malodorous livestock waste lagoons and reduce odor through degradation of various volatile organic compounds.
In one preferred embodiment of the invention, a biologically pure culture of bacteria having some or all of the identifying characteristics of RPS9 is provided. In this embodiment, the identifying characteristics of RPS9 may include a bacteriochlorophyll xcex1 (xe2x80x9cBchlxe2x80x9d) profile, a cell extract absorption spectra, a MIDI-FAME (Microbial Identification System-Fatty Acid Methyl Ester) profile, and a species specific rRNA profile. The biologically pure culture bacteria is preferably capable of degrading malodorous volatile organic compounds such as fatty acids (e.g., butanoic acid, pentanoic acid, hexanoic acid, and heptanoic acid) and aromatic compounds (e.g., phenol, para-cresol, and 3-methyl-indole).
In another preferred embodiment, a method of inducing the growth of RPS9 and variants thereof in a livestock waste lagoon is provided by controlling lagoon conditions such as pH, temperature, and organic load. Growth is enhanced by adjusting the temperature to at least at about 22xc2x0 C. or above, the pH to about pH 6.9 to about 7.8, and the organic load to a protein concentration of about 1 g per liter and, preferably, a dry weight below about 4 g per liter.
In another preferred embodiment, an inoculum comprising a biologically pure culture of RPS9 or variant thereof and a suitable carrier is provided. The inoculum is used to inoculate a livestock waste lagoon. The inoculum is typically used to inoculate a livestock waste lagoon by providing from about 1 ml to about 5 ml of the bacterium (at a concentration of about 2 mg cell protein/ml) to the lagoon by any suitable method, preferably after adjusting the temperature, pH and organic load of the livestock waste lagoon.
In a further preferred embodiment, a method of genetically reconstituting a RPS9 strain is provided by introducing a vector comprising a gene encoding a protein product, a promoter to control expression of the protein product, and a selection gene. Preferably, the vector system does not require the continual presence of antibiotics to maintain the vector in the RPS9 strain. The promoter preferably does not require the addition of a substrate to induce expression of the protein product. The selection gene is preferably a gene essential to the survival of the RPS9 strain. A particularly preferred selection gene is the ffh gene. Reece, K. R and Phillips, G. J. (1995); Phillips, G. J. and T. J. Silhavy (1992). The gene may be inserted into the vector using any suitable recombinant DNA technique or method. The vector may be introduced into the RPS9 strain using any suitable technique or method.
In a yet another preferred embodiment, a fermentation system and method for producing a protein is provided. A genetically reconstituted RPS9 strain or variant thereof is grown in a livestock waste lagoon. The RPS9 cells are preferably separated from the liquid waste and induced to express a protein product in an inducing media. The protein product is preferably separated from the induced RPS9 cells. The fermentation system and method provides significant cost savings advantages over standard fermentation methods since the RPS9 are grown in waste products and do not require addition of antibiotics to maintain vectors, or exogenous compounds to induce expression of the protein product.
Additional embodiments and advantages of the present invention will be set forth in part in the description that follows, and in part will be obvious from the description, or may be learned through the practice of the invention. The objects and advantages of the invention will be attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

Rhodobacter strain for odor remediation of anaerobic livestock waste lagoons and biomass production

Iowa State University Research Foundation, Inc.


A reproducing/recording apparatus includes a first reproducing/recording mechanism (21) for reproducing data from and/or recording data onto a cartridge/disk combination (first disk) (1) or a bare disk (second disk) (2), the disk main body (1A) being contained in the cartridge (1B). The first reproducing/recording mechanism (21) has a traversing mechanism (50) disposed oppositely relative to the recording area of the first disk (1) or the second disk (2), a clamping mechanism (60) disposed oppositely relative to the traversing mechanism (50) with the first disk (1) or the second disk (2) interposed between them in order to clamp the first disk (1) and a keep member (64) adapted to bias the first disk (1) toward the side of the first disk tray at the time of clamping the first disk (1) by the clamping mechanism (60). The disk made to show a right attitude because the disk is pressed by the keep member (64) even when the first disk (1) is pushed up at an edge thereof by the sensor section arranged at the traversing mechanism (50).

1. Field of the Invention
The present invention relates to a reproducing/recording apparatus for reproducing data from and/or recording data onto a disk contained in a cartridge to form a cartridge/disk combination or a bare disk without cartridge.
2. Description of Related Art
A reproducing/recording apparatus for reproducing information from and/or recording information onto a disk has been used.
Such reproducing/recording apparatus includes a reproducing/recording mechanism for reproducing information from and/or recording information onto a disk mounted on a disk tray and a disk that is mounted on a disk tray is moved into and out from the apparatus main body through a disk inlet/outlet port.
Disks that can be used for information reproducing/recording include those that are contained in a cartridge, which may be referred to as cartridge/disk combinations, and bare disks that are not contained in a cartridge.
The reproducing/recording mechanism on which such a cartridge/disk combination is mounted normally includes a traversing mechanism disposed oppositely relative to the recording area of the disk main body and a clamping mechanism for clamping the center of the cartridge/disk combination arranged vis-à-vis the traversing mechanism.
Conventional reproducing/recording apparatus are provided at the traversing mechanism thereof with switches (not shown) that are used to acquire information if it is possible to write information on the cartridge/disk combination and the switches are provided with a sensor section that urges the periphery of the cartridge/disk combination.
Thus, when a cartridge/disk combination is mounted on the reproducing/recording mechanism, it can be pushed by the sensor section and become inclined. If the center of the cartridge/disk combination is clamped by the clamping mechanism, the cartridge/disk combination may not restore the proper attitude. Then, there arises a problem that the information reproducing/recording operation may not be performed properly.

This patent is subject to a terminal disclaimer.


A system for the detection of abnormalities in a medical image of a subject. The system includes an examination bundle, a learning engine, and a detecting engine. The examination bundle includes at least one medical image of the subject from a first modality and at least one medical image of the subject from a second modality. The learning engine is employed for determining the characteristics of abnormalities within the at least one medical image from the first modality and the at least one medical image from the second modality. The detecting engine is employed for detecting abnormalities within at least one of the medical images comprising the examination bundle.

Medical imaging plays an important role in the screening, diagnosis, and/or treatment of many diseases because medical images enable a physician to view the internal anatomical structure of a patient or to visualize physiological or metabolic information. A variety of different imaging techniques or modalities can be used in clinical medicine. Some well known techniques/modalities include X-ray and computed tomography (CT), ultrasound, nuclear medicine, ultrasonic imaging, and magnetic resonance imaging (MRI). X-ray and CT, ultrasound, and MRI produce images of anatomical structure, whereas nuclear medicine produces images depicting metabolic uptake or biodistribution of radioactive compounds in various tissues (organs or tumors). Other modalities for imaging functional characteristics of physiological systems include functional MRI (fMRI), single photon emission computed tomography (SPECT), and positron emission tomography (PET). Still other modalities capture still images or video streams of internal structures by using a camera housed inside a scope. These modalities include colonoscopy, bronchoscopy, endoscopy, and capsule endoscopy.
Different techniques/modalities each have their strengths and weaknesses. For example, X-ray imaging has high spatial and intensity resolutions, shows bony anatomy with high detail, and is relatively inexpensive to use; however, it also presents the viewer with complex two-dimensional (2-D) views of superimposed anatomy. X-ray imaging can also have difficulty resolving soft tissue features.
MRI has the advantage of displaying three-dimensional (3-D) images of soft tissues with high contrast and high spatial resolution, and it does not involve ionizing radiation (as does X-ray and CT); however, MRI does not image bone well. CT imaging, based on X-ray absorption, produces 3-D images of bony anatomy, and increasingly, good definition of soft tissue, although MRI remains the preferred modality for viewing soft tissue.
Ultrasound imaging is easily portable, relatively inexpensive, and does not involve ionizing radiation. It has high spatial resolution and is extremely fast, enabling real-time frame capture rates. More recently, one unique and potentially powerful use of ultrasound has been discovered: measuring the elasticity of tissue, which can be useful in distinguishing tumor tissue from healthy tissue, for example, in the breast. A disadvantage of ultrasound is that it cannot easily image through gas or bones, making it difficult to obtain images of some organs.
Nuclear medicine provides images depicting metabolic information that can be early indicators of pathological conditions; however, it can be difficult to accurately pinpoint the location of anomalies in the body due to the lack of structural information in the images.
SPECT uses tomographic principles to provide a series of 2-D nuclear medicine images from nearby slices of tissue, effecting a 3-D nuclear medicine image; however, the spatial resolution can be slightly degraded. PET also is a tomographic technique that measures physiology and function, and provides images with higher spatial resolution and signal to noise ratio (SNR) than SPECT images. However, PET systems are very costly, because of the need for a cyclotron to produce positron-emitting nuclides. fMRI is not frequently used in clinical applications, with the exception of surgical planning, which aims to determine the areas of the brain that respond to specific cognitive tasks, in order to avoid those areas during surgery.
Scopes enable a visual inspection of the interior of a body lumen, such as the bronchi (bronchoscopy), the colon (colonoscopy), or upper gastrointestinal tract (endoscopy). Capsule endoscopy does not actually use a scope, but rather a swallowable capsule containing a camera that captures images while traveling through the entire gastrointestinal tract. Capsule endoscopy is more comfortable for the patient than endoscopy, and allows visualization deep within the intestines. However, the capsule and/or camera cannot be controlled or fixed on certain areas of interest, as can be done with a scope.
In some clinical applications, two or more modalities are used to capture medical images. In some applications, an image from one modality is used to screen for a disease, and then a subsequent image from another modality (usually of a higher resolution and/or diagnostic utility) is captured to verify a diagnosis or to gauge the progression of the disease. One example of this is when chest (X-ray) radiography is used to screen for lung nodules, lung cancer, or other respiratory diseases. Suspicious findings may cause a radiologist to order CT imagery to provide a high-resolution 3-D visualization of the affected area. Another example is (X-ray) mammography that is used to screen for breast cancer; a positive indication of breast cancer may then require a 3-D MRI of the breast for further investigation of tumors. A more recent example of a screening procedure is the use of CT imagery for virtual colonoscopy; the identification of suspicious regions or suspected polyps could result in a follow-up colonoscopy.
In addition to the use of images from multiple modalities in a screening/verification process, another common use of multi-modal medical imaging is to provide both anatomical and functional information. For example, in brain imaging, when cancer is suspected or diagnosed, CT and/or MR images may be captured to show the structure of the brain and any abnormalities, and PET or SPECT images may be captured to show any metabolic behavior of tumors or lesions. The combination of CT and PET imagery is used in the chest as well, in order to examine images of the lungs, liver, and kidneys. The CT/PET combination has been well received and devices capable of capturing both modalities simultaneously have been emerging in the marketplace (General Electric's Discovery LS PET/CT system and Siemens' biograph™ are two examples).
In other situations, images from multiple modalities may be captured even if the modalities provide some sort of structural information. CT and MR images of the brain or abdomen, or of orthopedic sites, may be captured at different times. The emergence of sonoelasticity, or measuring elastic properties of tissue using ultrasonic imaging, can be used to examine elasticity of the breast, providing structural information that complements mammograms or MR breast images.
However, even though medical imaging modalities provide a wide variety of visual information, many diseases are difficult to detect or diagnose. For example, one source estimates that around 20% of breast cancer cases are not detected by mammography.
In efforts to detect various types of cancers and of other diseases, many researchers have developed computer-assisted detection/diagnosis (CAD) techniques that aid the radiologist in detecting abnormalities.
CAD techniques directed to mammography are known. Refer, for example, to U.S. Pat. Nos. 5,633,948, 5,732,697, 5,941,832, 6,075,878, 6,266,435, 6,272,233, 6,418,237 and 6,553,356, and U.S. Patent Application Nos. 2001/0031076 and 2002/0057826.
CAD techniques applied to the detection of pulmonary nodules are also known. Refer, for example, to U.S. Pat. Nos. 5,539,838, 5,825,936, 5,881,124, 5,987,094, 6,125,194 and 6,609,021, U.S. Patent Applications Nos. 2003/0076992, 2003/0095696, 2003/0099388, and 200/30105395, and European Patent Nos. EP1,129,426, EP1,249,006, and EP1,395,165.
CAD applied to the detection of colorectal cancer is described in U.S. Pat. Nos. 4,981,783, 5,628,314.and 5,983,211, and U.S. Patent Application Nos. 2002/0187502, 2002/0022240, and 2003/0032860.
Osteoporosis and bone disease are the subject of CAD techniques in U.S. Pat. Nos. 4,913,157, 5,247,934, 5,673,298, 5,817,020, 5,902,240 and 6,143,506.
Even though these prior art techniques assist the medical practitioner in detecting and/or diagnosing disease, they apply to individual medical images or to multiple medical images from a single modality.
Some progress has been made in aligning and/or fusing images from multiple modalities. For example, U.S. Pat. No. 6,266,453 (Hibbard) is directed to a system for displaying multimodal image data (CT+MRI or CT+PET brain images) on a graphical user interface (GUI), enabling manual or automatic registration and fusion. U.S. Pat. No. 6,539,127 (Roche) relates to a method for registering general multimodal image data, based on correlation ratios between the data sets. U.S. Pat. No. 6,640,130 (Freeman) is directed to a system for fusing anatomic images with spectroscopic images of tissue or organs. U.S. Patent Application No. 2003/0216631 (Bloch) employs free form deformations to register PET and CT thoracic and abdominal images.
Although these methods and systems related to aligning and fusing images from multiple modalities, they do not address how to utilize the multimodal imagery to provide an enhanced method for detecting and/or diagnosing disease.
Existing CAD methods and systems apply to individual medical images or to multiple medical images from a single modality, and as such, they are not optimal when applied to a collection of images from multiple modalities. Registration and fusion techniques, while providing visually meaningful information to the medical practitioner, do not provide the same level of assistance as CAD systems.
The present invention addresses the problems and limitations of the prior art by providing a system and method for computer assisted detection and/or diagnosis of disease or abnormalities utilizing imagery from multiple modalities.


A magnetic assembly includes plural first magnetic cores, plural coil windings and a second magnetic core. Each of the plural first magnetic cores includes plural legs and a first connection part. The first connection part is connected with first terminals of the plural legs. The first connection part of the first magnetic core at an upper position is located adjacent to second terminals of the plural legs of the adjacent first magnetic core at a lower position. Each coil winding is wound around at least one leg of the plural legs of the corresponding first magnetic core so as to form a magnetic element of the corresponding converter. The second magnetic core is stacked over the plural first magnetic cores. The second magnetic core is located adjacent to the second terminals of the legs of the topmost first magnetic core.

Generally, plural converters are connected with each other in parallel in a power supply system when high power is required. Each converter comprises at least one magnetic element such as a transformer or an inductor. The magnetic element comprises a magnetic core and a coil winding. The coil winding is wound around the magnetic core to form a closed magnetic flux path. Consequently, the magnetic element is produced.
Since the magnetic element occupies large fractions of volume and weight of the overall power supply system, it is an important issue to reduce the volume and weight of the magnetic element in order to increase the power density of the power supply system. However, since the magnetic elements of the plural converters have individual magnetic cores and the magnetic flux paths are independent, the volume and weight of the overall power supply system are increased and the fabricating cost of the power supply system is high. Moreover, during operations of the power supply system, the magnetic core of the magnetic element of each converter will result in a large magnetic loss. Since the magnetic cores of the magnetic elements of the plural converters in the conventional power supply system are independent and the magnetic flux paths are independent, the conventional power supply system has large magnetic loss and volume.
Therefore, there is a need of providing a magnetic assembly and a power supply system with the magnetic assembly in order to overcome the above drawbacks.

Magnetic assembly and power supply system with same


A flexible chair that includes a seat member with seat bottom and back rest portions, first and second pairs of legs, and a plurality of cross members. The pair of first legs are pivotly connected to rearward positions of the seat bottom portion and extend downwardly and forwardly from the seat bottom portion. The pair of second legs are pivotly connected to forward positions of the seat bottom portion and extend downwardly and rearwardly from the seat bottom portion, such that the first legs cross the second legs. The plurality of cross members connect the first and second legs together such that the seat member is rearwardly reclinable against a resilient force provided by at least one of the first pair of legs, the second pair of legs and the plurality of cross members.

It is presently known to make a chair that flexes, where as the back tilts, the seat travels forward and slightly upward. Such a chair is disclosed in U.S. Pat. Re. 36,335.
However, such a chair does not have arm rests, and does not provide a simple construction that allows the chair to resiliently recline in a hammock-like fashion, while still being stackable.


An illustrative SerDes receiver includes: a front-end filter, a precomputation unit, a selection element, and a controller. The front end filter converts a receive signal into a linearly-equalized signal. The precomputation unit accepts the linearly-equalized signal with or without a subtracted feedback signal, and employs a set of comparators with threshold values that depend on a first post-cursor ISI value F1, the set of comparators operating to generate a set of tentative symbol decisions. The selection element derives a selected symbol decision from each set of tentative symbol decisions, thereby deriving a sequence of symbol decisions from the receive signal. The controller constrains F1 if the receive signal uses a PAM4 signal constellation, setting F1 to equal zero if the receive signal is conveyed via a low-loss channel and to equal one if the receive signal is conveyed via a high-loss channel.

Digital communications occur between sending and receiving devices over an intermediate communications medium, or "channel" (e.g., a fiber optic cable or insulated copper wires). Each sending device typically transmits symbols at a fixed symbol rate, while each receiving device detects a (potentially corrupted) sequence of symbols and attempts to reconstruct the transmitted data. A "symbol" is a state or significant condition of the channel that persists for a fixed period of time, called a "symbol interval." A symbol may be, for example, an electrical voltage or current level, an optical power level, a phase value, or a particular frequency or wavelength. A change from one channel state to another is called a symbol transition. Each symbol may represent (i.e., encode) one or more binary bits of the data. Alternatively, the data may be represented by symbol transitions, or by a sequence of two or more symbols.
Many digital communication links use only one bit per symbol; a binary '0' is represented by one symbol (e.g., an electrical voltage or current signal within a first range), and binary '1' by another symbol (e.g., an electrical voltage or current signal within a second range), but higher-order signal constellations are known and frequently used. In 4-level pulse amplitude modulation (PAM4), each symbol interval may carry any one of four symbols, denoted as −3, −1, +1, and +3. Two binary bits can thus be represented by each symbol.
Channel non-idealities produce dispersion which may cause each symbol to perturb its neighboring symbols, a consequence known as inter-symbol interference (ISI). ISI can make it difficult for the receiving device to determine which symbols were sent in each interval, particularly when such ISI is combined with additive noise.
To combat noise and ISI, receiving devices may employ various equalization techniques. Linear equalizers generally have to balance between reducing ISI and avoiding noise amplification. Decision Feedback Equalizers (DFE) are often preferred for their ability to combat ISI without inherently amplifying the noise. As the name suggests, a DFE employs a feedback path to remove ISI effects derived from previously-decided symbols.
A standard textbook implementation of a DFE employs a number of cascaded circuit elements to generate the feedback signal and apply it to the received input signal, all of which must complete their operation in less than one symbol interval. As symbol intervals continue to shrink, this implementation becomes infeasible with currently available silicon semiconductor processing technologies. Accordingly, alternative implementations have been proposed such as those disclosed in U.S. Pat. No. 8,301,036 ("High-speed adaptive decision feedback equalizer") and U.S. Pat. No. 9,071,479 ("High-speed parallel decision feedback equalizer"). These alternative implementations exploit the use of precomputation modules, which greatly increase the required number of fast comparators and hence greatly increase the receiver's power requirements. U.S. Pat. No. 9,935,800 ("Reduced complexity precomputation for decision feedback equalizer") discloses one technique for reducing the number of fast comparators, yet there remains further room for improvement.


Apparatus and methods usable for wavelength references and measurement of wavelength of a light beam. The apparatus comprise at least two wavelength reference or filter elements positioned in a light beam, each wavelength reference element having a different free spectral range and operable to define a joint free spectral range, and a detector positioned in the beam after the wavelength reference elements. The joint free spectral range provided by the multiple wavelength reference elements results in a joint transmission peak that is centered at a unique wavelength, and maximum optical power detectable from the beam by the detector occurs at the center wavelength of the joint transmission peak.

There is an increasing demand for tunable lasers for test and measurement uses, wavelength characterization of optical components, fiberoptic networks and other applications. In dense wavelength division multiplexing (DWDM) fiberoptic systems, multiple separate data streams propagate concurrently in a single optical fiber, with each data stream created by the modulated output of a laser at a specific channel frequency or wavelength. Presently, channel separations of approximately 0.4 nanometers in wavelength, or about 50 GHz are achievable, which allows up to 128 channels to be carried by a single fiber within the bandwidth range of currently available fibers and fiber amplifiers. Greater bandwidth requirements will likely result in smaller channel separation in the future.
DWDM systems have largely been based on distributed feedback (DFB) lasers operating with a reference etalon associated in a feedback control loop, with the reference etalon defining a wavelength grid. Statistical variation associated with the manufacture of individual DFB lasers results in a distribution of channel center wavelengths across the wavelength grid, and thus individual DFB transmitters are usable only for a single channel or a small number of adjacent channels.
Continuously tunable external cavity lasers have been developed to overcome the limitations of individual DFB devices. Various laser tuning mechanisms have been developed to provide external cavity wavelength selection, such as mechanically tuned gratings used in transmission and reflection. External cavity lasers must be able to provide a stable, single mode output at selectable wavelengths while effectively suppress lasing associated with external cavity modes that are within the gain bandwidth of the cavity. These goals have been difficult to achieve. Effective operation of tunable lasers requires reliable wavelength reference systems for determining wavelength of laser output. Available wavelength reference systems used in external cavity lasers and other optical systems are subject to change due to aging and related changes in optical components during use, and can be unreliable. There is a need for wavelength reference apparatus methods that provide easy and accurate wavelength determination and which are reliable and not susceptible to variation due to aging during use. The present invention satisfies these needs, as well as others, and overcomes the deficiencies found in the background art.

Wavelength reference apparatus and method


A capsule dryer utilizes an upper level having a plurality of drying baskets and a lower level having a plurality of drying baskets disposed beneath the upper level of drying baskets. The footprint of the capsule dryer is thus reduced while providing a same or superior drying capabilities. Furthermore, the drying baskets at the different levels are independently controlled.

The present invention relates to soft capsule making and more particularly to a tumbler-dryer used for making soft capsules.
Typical soft encapsulation machines for use in making pharmaceutical medicines form at least two flexible gelatin sheets or ribbons by cooling molten gelatin on separate drums. The sheets are lubricated and guided into communication with each other over co-acting dies. Simultaneously, a desired quantity of fill material is dispensed between the sheets in synch with cavities in the outer surfaces of the dies to produce soft capsules. The soft capsules are transported from the encapsulation machine to a drying machine to dry (in other words, remove moisture from) the soft capsules and make them into their final form. The soft capsules are typically transported from the encapsulation machine to the dryer by a conveyor that extends along the front of the encapsulation machine.
The drying machine typically includes a plurality of axially aligned drying drums or baskets. The baskets are arranged adjacent one another and allow capsules to flow from one basket into the next adjacent basket. Heated air is routed through the various baskets to dry the capsules therein. Furthermore, after passing through the drying baskets, the capsules may also need to be routed through a drying tunnel wherein further moisture is removed from the capsules to obtain the desired state of dryness or moisture content. This drying process can require a significant number of baskets to dry the capsules to a desired moisture content. The capsules get dryer in each subsequent drying basket they flow into. This results in a large dryer requiring a large foot print or area of a factory in which it is employed. Furthermore, the use of drying tunnels also undesirably increases the area or footprint of the overall drying equipment required to dry the capsules to a desired moisture content.
Space in the manufacturing facility, however, may be at a premium. Therefore, it would be advantageous to reduce the size and/or footprint of the drying machines. Furthermore, it would be even more advantageous if a larger capacity or throughput can be achieved in the same or smaller footprint.
Typically, all of the baskets of conventional machinery are driven at a same rotational speed by a single belt drive unit. The required rotational speed of the baskets, however, can vary based upon the moisture content in the capsules. Thus, as the capsules get dryer and pass from one drying basket to the next, the required rotational speed may change. Since all the baskets are driven at the same rate of speed by a single belt drive mechanism, however, all of the baskets must be rotated at the same speed which will correspond to the speed of the most demanding of the drying baskets. The rotating of all the baskets at a same or uniform rotational speed can be inefficient and slow the drying process. Accordingly, it would be advantageous to be able to rotate the different baskets at different rotational speeds depending upon the needs of the capsules being dried therein.
A capsule dryer, according to the principles of the present invention, utilizes an upper level having a plurality of drying baskets and a lower level having a plurality of drying baskets disposed beneath the upper level of drying baskets. By providing upper and lower levels of drying baskets, the footprint of the capsule dryer can be reduced while providing the same or superior drying capabilities. Accordingly, the required area in a factory using the capsule dryer can be reduced thus allowing additional space in the factory for other equipment or tasks.
In another aspect of the present invention, the rotation of the drying baskets at the different levels are independently controlled and driven. This advantageously enables the upper and lower level baskets to be driven at different rotational speeds according to the needs of the capsules being dried therein. Accordingly, more efficient operation of the capsule dryer can be achieved along with an increase in throughput capacity.
In yet another aspect of the present invention, the capsule dryer utilizes a drive mechanism to rotate the drying drums. There is a programmable control device which is operable to control operation of the drive mechanism. The use of a control device is advantageous in that it facilitates the controlling of the operation and can also be integrated into or utilize the same control device that controls the encapsulation machine that produces the soft capsules. The control device can also control the routing of the capsules from one drying basket to the next drying basket. The control device is advantageous in that it can facilitate the transferring of capsules from one basket to the next and coordinate the same with all the baskets. This coordination can increase the throughput of the capsule dryer, increase the efficiency of the drying operation and reduce the complexity of the control system.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.


A three-dimensional image capturing device comprises a plurality of laser devices, and an imaging device, such as a CCD, having a plurality of photo-diodes. Each of the laser devices radiates a pulse modulated laser beam so as to detect distance information or data relating to a topography of a measurement subject. The laser beam is radiated onto the measurement subject and a reflected light beam is sensed by the CCD. Signal charge corresponding to a distance from the image capturing device to the measurement subject is accumulated in each of the photo-diodes, and thus the above distance information is sensed. Each laser beam, respectively radiated from each of the laser devices, shares illuminating area at the distance of the measurement subject, so that radiant energy of each laser beam can be reduced by sharing a single distance measurement operation among the plurality of laser devices.

1. Field of the Invention
The present invention relates to a three-dimensional image capturing device by which a three-dimensional shape of a measurement subject, which is to be measured, is captured by a time-of-flight measurement and its laser for emitting a measurement light beam.
2. Description of the Related Art
A three-dimensional measurement using a three-dimensional image capturing device is classified as an active system, in which light, an electric wave or sound is radiated onto a measurement subject, and a passive system in which the light, electric wave or sound is not output. The active system comprises the time-of-flight measurement, a phase detection using a modulated light wave, a triangulation, a moiré topography, and so on, and the passive system comprises a stereo vision system, and so on.
An active system device is bulky in comparison with that of the passive system, since the device requires a laser beam output mechanism. However, the active system device is superior regarding a distance measurement resolution, a measuring time, a measuring range and so on, and thus, despite the bulkiness, the device is utilized in various fields. In a three-dimensional image capturing device, described in "Measurement Science and Technology" (S. Christies et al., vol. 6, p. 1301–1308, 1995), a pulse-modulated laser beam irradiates a whole of a measurement subject through an illumination lens, and a reflected light beam, which is reflected by the measurement subject, is received by a two-dimensional CCD sensor to which an image intensifier is attached, so that an image signal, corresponding to the reflected light beam, is converted to an electric signal. ON-OFF control of the image intensifier is carried out by a gate pulse, which is synchronized with the pulse radiation of the laser beam. According to the device, since an amount of received light, based on the reflected light beam from the measurement subject, which is positioned far from the device, is less than that of received light based on a reflected light beam from a measurement subject, which is close to the measurement subject, an output corresponding to a distance between the measurement subject and the device can be obtained for each pixel of the CCD.
However, if a person is standing nearby the measurement subject and is in the range of the divergent laser illumination, a laser beam may become incident on an eye of the person and may damage the retina. Therefore, three-dimensional measurement using laser beam may be harmful to the retina of a bystander during the measurement.

Three dimensional image capturing device and its laser emitting device


Disclosed is a composition comprises or is produced from a biopolymer, an olefin copolymer, and an optional polymer wherein the biopolymer comprises repeat units derived from a glycoside. Also disclosed is an article comprising or produced from the composition.

Biodegradable polymers such as polymers from glycosides, poly(lactic acid), polyvinyl alcohol, polycaprolactone, have a broad range of industrial and biomedical applications as films. However, articles made from these materials or the films often suffer deficiencies such as brittleness, poor impact strength, poor tear strength, poor clarity, water sensitivity, poor processability, etc. In many instances selected deficiencies can be improved by preparing blends of biopolymers with other biopolymers or synthetic polymers. A problem associated with blending biopolymers is compatibility with other polymers, especially less polar polymers. Orientation with strain assisted crystallization of amorphous polymers may be used to increase the stiffness or modulus of films as well as elongation. Such orientation process decreases the elongation-at-break in the direction of the lower orientation.
Also, utilization of starch polymers is attractive due to the renewable nature and the compostability, which eases burdens on landfills, but articles fabricated from starch are very brittle, and this poor impact toughness limits commercial applications of pure starch articles. Starch can be blended with a variety of polymers to improve the properties of starch, but as the starch content increases the tensile strength and elongation at break both decrease. See, Bikiaris (D. Bikiaris and C. Panayiotou, Journal of Applied Polymer Science, 1998, vol 70, p. 1503). Anhydrous plasticized starch blended with polyethylene has been compatibilized with maleic anhydride-grafted polyethylene (Bikiaris). See also, WO2006042364. Maleic anhydride-grafted polyethylene has also been used in starch alloys containing 20 to 80% starch (e.g., U.S. Pat. No. 5,635,550) and in a blend of destructurized starch (e.g., U.S. Pat. No. 5,409,973).
It would also be desirable to produce articles from resin compositions with >80% starch content thereby improving the biodegradability of the resulting resin composition. These articles are more difficult to toughen because they comprise a higher proportion of the brittle starch and could also have the brittle starch as the continuous or co-continuous phase. For example, use of hydroxypropyl-modified, high-amylose starch in combination with less than 10% polyvinyl alcohol has been described (WO 00/36006). However, these articles have inferior impact properties, particularly at <40% relative humidity.
Accordingly, it is desirable to develop a modified composition, and its blends, with improved processability and physical properties and to articles made from the composition or from a multilayer structure comprising the composition.


Embodiments include low voltage embedded memory having conductive oxide and electrode stacks. A material layer stack for a memory element includes a first conductive electrode. A conductive oxide layer is disposed on the first conductive electrode. The conductive oxide layer has a plurality of oxygen vacancies therein. A second electrode is disposed on the conductive oxide layer.

For the past several decades, the scaling of features in integrated circuits has been a driving force behind an ever-growing semiconductor industry. Scaling to smaller and smaller features enables increased densities of functional units on the limited real estate of semiconductor chips. For example, shrinking transistor size allows for the incorporation of an increased number of memory devices on a chip, lending to the fabrication of products with increased capacity. The drive for ever-more capacity, however, is not without issue. The necessity to optimize the performance of each device becomes increasingly significant.
Embedded SRAM and DRAM have problems with non-volatility and soft error rates, while embedded FLASH memories require additional masking layers or processing steps during manufacture, require high-voltage for programming, and have issues with endurance and reliability. Nonvolatile memory based on resistance change, known as RRAM/ReRAM, typically operates at voltages greater than 1V, typically requires a high voltage (>1V) forming step to form a filament, and typically have high resistance values limiting read performance. For low voltage non-volatile embedded applications, operating voltages less than 1V and compatible with CMOS logic processes may be desirable.
Thus, significant improvements are still needed in the area of nonvolatile device manufacture and operation.

Low voltage embedded memory having conductive oxide and electrode stacks


An open roof construction for a vehicle includes a first closing element movably supported by a stationary part and is configured to move to an upward position with at least its front edge. A second closing element movably supported by the stationary part and is positioned rearward of the first closing element. The second closing element moves between a closed position in which it closes said roof opening and an at least partly open position. An air guide on a lower side of the first closing element guides and directs the air caught by said first closing element when in its upward position during driving of the vehicle to create a boundary layer of air which is situated between the outside and the inside of the vehicle at the position of the roof opening when said second closing element is in its at least partly open position.

The discussion below is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.
Aspects of the present invention relate to an open roof construction for a vehicle having a roof opening in a fixed roof portion, comprising: a stationary part for attaching the open roof construction to the fixed roof portion, a first closing element movably supported by the stationary part and being capable of moving to an upward position with at least its front edge, particularly swiveling around a lateral axis with its frontal edge upwards to an upward position, and a second closing element, which is movably supported by the stationary part and being positioned rearward of the first closing element, said second closing element being capable of moving between a closed position in which it closes said roof opening and an at least partly open position.
Such roof assembly is known from EP 0 903 253 of applicant. The first closing element is a flap in the fixed roof portion which comprises a flow channel extending in upward direction in order to direct air over the roof opening.


An improved method for processing of nickel bearing saprolite and limonite ores to recover the valuable minerals contained therein, comprising leaching the ore with nitric acid to form a slurry; separating the iron values by precipitation, removing the iron values; forming a liquid/solid residue in which nickel, cobalt and magnesium are in solution, and manganese and aluminum are solid residues in oxide form; conducting a liquid-solid separation and removing the solids; and recovering the nickel, cobalt, and manganese from the liquid-metal concentrate. The leachate is recovered and nitric acid from the leachate is recycled.

The compositions of ores vary tremendously, even when taken from the same mining site. Limonite and saprolite ores usually contain iron, nickel, cobalt, magnesium, manganese, chromium, and/or aluminum. Known processes for treating high magnesium saprolite ores or high-iron limonite type ores are generally high cost processes, whereas the present invention is an improved, cost-effective process which can handle a full range of ores, including transitional ores. The term "ores" as used herein is intended to mean oxide and sulfide ores, metallurgical wastes, and metal-bearing materials, it being understood that metals can be combined with other elements.

Method of recovering metal values from ores


A radio communication system includes a base station and a plurality of terminals including a new terminal. The system enables deletion of registration data relating to the new terminal when an end of communication between the new terminal and another terminal is detected or when one of the terminals is placed in a charger base. A new terminal is installed in the radio communication system by transmitting a system code of the base station from a terminal which has already been registered to the new terminal. In addition, communication between terminals is accomplished without sending a request signal to the base station.

1. Field of the Invention
The present invention relates to a radio communication system and a method of expanding a terminal with respect to a base station of the radio communication system.
2. Description of the Related Art
Presently, there is a radio communication system capable of communicating with remote terminals through a base station connected to a communication network. An example of this communication system is a PHS (Personal Handyphone System) which is to be put into practice in Japan. The specification of the PHS is standardized in RCR STD-28. The PHS has a base station installed in an indoor space (e.g., a house or an office) or in an outdoor space (e.g., a public space). Each of the indoor and outdoor base stations can be connected to terminals through radio communication.
Further, the standard defines transceiver communication by which direct conversation can be made between terminals of like transceivers. Transceiver communication is allowed for only those terminals which have the same base identification information (in particular, indoor terminals).

Method and apparatus for expanding a radio communication system and enabling communication between terminals


The present invention provides a motor control system and method thereof. The motor control system comprises a motor controller and a compensation device. The motor controller is used for generating a motor control output according to a reference signal and a first signal. The compensation device is used for generating a compensated motor control output according to the motor control output and a second signal. Moreover, the compensation device utilizes the compensated motor control output to reduce the steady-state phase error between the first signal and the reference signal.

1. Field of the Invention
The present invention relates to a motor control system and method thereof, especially to a motor control system and method thereof for reducing the steady-state phase error and the transition time.
2. Description of the Prior Art
Please refer to FIG. 1(a), FIG. 1(b), and FIG. 1(c). FIG. 1(a) is a schematic diagram of a motor system 10 of the prior art. FIG. 1(b) is a schematic diagram of a motor controller 30 of the prior art. FIG. 1(c) is a schematic diagram of a transfer function of the motor controller 30 of the prior art. The motor system 10 of the prior art usually comprises a motor device 12, a motor controller 30, a pulse width modulation (PWM) generator 26, and a resistance-capacitance (RC) filter 28. The motor controller 30 is used for controlling the motor device 12. As shown in FIG. 1(b), the motor controller 30 comprises a frequency detector 11 and a phase detector 13. The frequency detector 11 is used for detecting the frequency error between a first feedback signal 44 and a reference clock signal 42. The phase detector 13 is used for detecting the phase error between the first feedback signal 44 and the reference clock signal 42. Furthermore, the motor controller 30 utilizes the frequency gain (Gf), the phase gain (Gp), and the sum gain (Gs) to adjust the frequency detector 11, the phase detector 13, and the sum result thereof, so as to determine the motor control output 31 and control the motor device 12 to achieve ideal predetermined frequency and phase. The schematic diagram of the transfer function of the motor controller 30 is shown in FIG. 1(c), i.e.
            G      s        ·          (                                    S            ·                          K              FD                        ·                          G              f                                +                                    K              PD                        ·                          G              p                                      S            )        ,wherein S is a Laplace variable of the signal frequency, KFD and KPD represent the gain of the frequency detector 11 and the phase detector 13 respectively, and Gf, Gp, and Gs are the programmable gain for adjusting the frequency detector 11, the phase detector 13, and the sum result thereof respectively. Although the motor system 10 has accurate frequency in steady state, there are still errors in the phase. The errors in the phase will affect the control manner of a device utilizing the motor system 10. For example, if the device utilizing the motor system 10 is an optical information recording/reproducing system, e.g. a CD-ROM drive, the CD-ROM drive will be affected by different control manners of the motor system, e.g. constant angular velocity (CAV) or constant linear velocity (CLV).
Please refer to FIG. 2(a) to FIG. 2(d). FIG. 2(a) is a schematic diagram of the radius (r) and the angular speed (rpm) of the CAV motor. FIG. 2(b) is a schematic diagram of the radius (r) and the angular speed (rpm) of the CLV motor. FIG. 2(c) is a schematic diagram of the radius (r) and the control voltage (Vm) of the CAV motor. FIG. 2(d) is a schematic diagram of the radius (r) and the control voltage (Vm) of the CLV motor. Under the CAV mode, the phase error is fixed because the inner and the outer angular speeds of the disc are the same even though the radii are different, so that the control of the motor is not being affected a lot. However, under the CLV mode, the phase error is different because the inner and the outer angular speeds of the disc are different by different radii, so that Gp and Gs should be adjusted to achieve better quality control. Moreover, before the motor system 10 of the prior art reaches the predetermined ideal angular speed and phase, it needs a period of time for the angular speed and the phase of the motor device 12 to reach the predetermined ideal value. This period of time is called transition time.
The motor controller 30 in the motor system 10 of the prior art needs a longer transition time for the frequency and the phase of the motor device 12 to converge to the predetermined ideal value. Moreover, even if the motor device 12 reaches the steady state and has the accurate frequency, there are usually still errors in the phase. In devices which request more accurate phase, this kind of the motor device 12 does not conform to the standard and causes problems in some devices. According to the above description, the motor system 10 of the prior art in steady state has some problems, e.g. larger phase error and longer transition time, to be improved.

Motor control system and method of the same


A method for measuring latency in a bi-directional ring network includes transmitting a latency measurement packet from an originating node to a peer node and noting a time of receipt of the packet at the peer node. The packet is then transmitted back to the originating node in the opposite direction, while recording in the packet an indication of a peer node difference between a time of transmission of the packet from the peer node to the originating node and the time of receipt of the packet at the peer node. A time of return of the packet to the originating node is noted, so as to determine an originating node difference between a time of transmission of the packet from the originating node to the peer node and the time of return of the packet to the originating node. The latency is calculated by taking a difference between the originating node difference and the peer node difference.

Network ring topologies are gaining in popularity, particularly in Internet Protocol (IP) networks. Such networks enable carriers to offer large bandwidth to users in a cost-effective manner, since each node in the network needs only two interfaces, rather than having to maintain a separate interface for each of the other nodes as in a mesh network.
Recently-developed bidirectional protocols provide efficient bandwidth utilization by enabling data to be transferred between any pair of nodes in either direction around the ring, while maintaining fast protection against faults. The two opposing traffic directions are commonly referred to as an inner ring and an outer ring. It will be understood, however, that in the context of the present patent application and in the claims, the terms "inner" and "outer," as well as "clockwise" and "counterclockwise," are used arbitrarily to distinguish between the two opposing directions of packet flow in a ring network. These terms are chosen solely for convenience of explanation, and do not necessarily bear any relation to the physical characteristics of the network.
The leading bidirectional protocol for high-speed packet rings is the Resilient Packet Rings (RPR) protocol, which is in the process of being defined as IEEE standard 802.17. Network-layer routing over RPR is described, for example, by Jogalekar et al., in "IP over Resilient Packet Rings" (Internet Draft draft-jogalekar-iporpr-00), and by Herrera et al., in "A Framework for IP over Packet Transport Rings" (Internet Draft draft-ietf-ipoptr-framework-00). A proposed solution for Media Access Control (MAC—protocol layer 2) in bidirectional ring networks is the Spatial Reuse Protocol (SRP), which is described by Tsiang et al., in Request for Comments (RFC) 2892 of the Internet Engineering Task Force (IETF). These documents are incorporated herein by reference. They are available at www.ietf.org.
Using protocols such as these, each node in a ring network can communicate directly with all other nodes through either the inner or the outer ring, using the appropriate Media Access Control (MAC) addresses of the nodes. Each packet sent over one of the rings carries a header indicating its destination node. The destination node recognizes its address in the header and strips the packet from the ring. All other nodes pass the packet onward transparently around the ring.
It is common in all sorts of data communication networks for network users to enter into a service level agreement (SLA) with their network service providers. The SLA specifies the quality of service (QoS) that the user is entitled to receive, based on a list of service parameters, such as network availability, percent of packets lost, mean latency of packet delivery, and deviation of the latency relative to the mean. Controlling latency is important particularly for real-time services, such as voice and video. In order to commit to a SLA that includes latency-related parameters, the service provider must be able to monitor the latency so as to verify compliance with the SLA.
Methods of network latency measurement are known in the art. For example, U.S. Pat. No. 5,235,593, to Grow et al., describes a ring latency timer for the purpose of latency measurement in token rings. A token ring is a closed, unidirectional ring network. A small token frame circulates around the ring. A node wishing to transmit on the ring captures the token and is then granted control of the transmission medium for a specified period. After capturing the token, the node transmits an information frame on the ring. When one of the nodes recognizes the destination address of the frame as its own, it copies the frame. After completing the transmission, the sending node releases the token for use by the other nodes.
In order to measure the ring latency, the node sends a special "void" frame before releasing the token. The void frame contains the address of the sending node in both the sender and destination fields. A latency counter is initialized when the void frame is released, and it is incremented every 16 clock cycles until the void frame is received back at the sending node. A latency bit is then set, and the value of the counter indicates the latency of the ring. The value remains valid until the latency bit is reset, whereupon the measurement is repeated.
The measured latency value gives an indication of the traffic load on the ring. The measured value is compared to a target token rotation time (TRTT) in order to determine whether and when each of the nodes in the ring is entitled to transmit data. Different TRTT values can be set for different classes of service on the ring, in order to allocate ring bandwidth preferentially to high-priority services. All of these TRTT values are compared against the same measured latency value to determine when the different services are allowed to transmit frames on the ring.
The methods described by Grow et al. can be used for measuring latency of transmission around the entire ring in a single direction, but they do not provide a means for measuring round-trip, node-to-node latency between a pair of nodes on the ring. Most methods known in the art for measuring such round-trip latency are based on measuring the time required for a packet to be sent from a source node to a destination node and then back again. These methods suffer from the drawback that the measured latency includes the time taken by the destination node to process the packet that it receives from the source node and to generate the response packet to send back to the source node.
Alternatively, it is possible to measure one-way latency from the source node to the destination node, and thus to eliminate the effect of the processing time at the destination node. Such a measurement, however, requires precise synchronization between the clocks at the source and destination nodes. Most networks do not maintain sufficiently accurate synchronization between nodes to enable meaningful measurements of one-way latency to be made. Therefore, costly hardware must typically be added to the network to enable accurate one-way latency measurements.