A cargo organizer includes a base, a storage compartment supported by the base and a deployment system for the storage compartment. The storage compartment includes a plurality of wall panels each having a hinged connection with the base and pivotable about its hinged connection between a stowed orientation and an upright orientation. The storage compartment is selectively deployable between a collapsed condition and an open condition. In the collapsed condition, each wall panel is lowered to its stowed orientation while, in the open condition, each wall panel is raised to its upright orientation. In the collapsed condition, the wall panels include an underlying wall panel and two adjacent overlying wall panels in spaced opposition about the underlying wall panel. The deployment system includes a strap system that connects an inboard portion of the underlying wall panel to respective outboard portions of the two adjacent overlying wall panels.

Vehicles may include various inner compartments that provide storage spaces for objects. For example, a sedan may include an enclosed trunk that is separate from its passenger compartment. A sport utility vehicle (SUV) or van, on the other hand, may include a rear cargo area behind its rear passenger seats that is open to its passenger compartment. To better secure objects and otherwise enhance the usability of the storage spaces provided by their inner compartments, these vehicles may include features for subdividing their inner compartments into smaller compartments. However, the features for subdividing the inner compartments may themselves occupy the storage spaces they provide or otherwise interfere with the use of the storage spaces. Moreover, it may not be convenient, or possible, to convert the subdivided inner compartments into un-subdivided inner compartments that provide larger storage spaces.

Cargo organizer with collapsible storage compartment


The present invention provides a power supply device for an electric vehicle that allows highly efficient operation of a compressor inverter. A power supply device for motor vehicle 10 has: a main circuit 13 having a power source 11, a DC-DC converter 18, and a main inverter 17 that drives a main motor 12; an auxiliary circuit 15 having an auxiliary inverter 19 that drives an auxiliary motor 14, a first electrical circuit 23 that is connected to the main circuit 13 on a primary side of the DC-DC converter 18, a second electrical circuit 24 that is connected to the main circuit 13 on a secondary side of the DC-DC converter 18, and a connection circuit 30 configured to be capable of selecting one of the first electrical circuit 23 and the second electrical circuit 24 as a path for supplying a direct current voltage to the auxiliary inverter 19; and a control device 16 that controls the connection circuit 30 when the main motor 12 is in power running operation so that switching between the first electrical circuit 23 and the second electrical circuit 24 is performed corresponding to a required voltage of the auxiliary inverter 19.

In recent years, the necessity to decrease the degree of dependence on petroleum as an energy source has been pointed out from the viewpoint of reducing carbon dioxide emission and securing energy, for the purpose of which technologies have been actively developed. Among such technologies, hybrid vehicles and electric drive vehicles that use an electrical power source (battery) as a driving source have raised great expectations. In this description, hybrid vehicles and electric drive vehicles are collectively referred to as electric vehicles. Various attempts have been made in order to improve the use efficiency of electrical energy as a power source for electric vehicles.
Patent Literature 1 discloses a system in which a DC-DC converter 103 is arranged between a high voltage power source 101 and a drive inverter 104, as shown in FIG. 9. In the system of Patent Literature 1, a control device 109 transmits control signals to the DC-DC converter 103 and the drive inverter 104, on the basis of the rotational speed and the torque of a drive motor 110. Thus, the boost ratio in the DC-DC converter 103 and the PWM duty in the drive inverter 104 are sequentially changed. Further, the control device 109 transmits control signals also to a compressor inverter 107, thereby sequentially changing the PWM duty in the compressor inverter 107 so as to supply an appropriate AC voltage to a compressor motor 111.

Power supply device for electric vehicle


Systems, methods, and apparatus to preheat weld wire are disclosed. An example welding torch includes a first contact tip configured to conduct welding current to a consumable electrode, a second contact tip configured to conduct preheating current to the consumable electrode, and a plurality of liquid cooling assemblies configured to conduct the preheating current and to conduct the welding current to the consumable electrode.

This disclosure relates generally to welding and, more particularly, to welding torches and methods to provide wire preheating for welding.
Welding is a process that has increasingly become ubiquitous in all industries. Welding is, at its core, simply a way of bonding two pieces of metal. A wide range of welding systems and welding control regimes have been implemented for various purposes. In continuous welding operations, metal inert gas (MIG) welding and submerged arc welding (SAW) techniques allow for formation of a continuing weld bead by feeding welding wire shielded by inert gas from a welding torch and/or by flux. Such wire feeding systems are available for other welding systems, such as tungsten inert gas (TIG) welding. Electrical power is applied to the welding wire and a circuit is completed through the workpiece to sustain a welding arc that melts the electrode wire and the workpiece to form the desired weld.
While very effective in many applications, these welding techniques may experience different initial welding performance based upon whether the weld is started with the electrode "cold" or "hot." In general, a cold electrode start may be considered a start in which the electrode tip and adjacent metals are at or relatively near the ambient temperature. Hot electrode starts, by contrast, are typically those in which the electrode tip and the adjacent metals' temperature are much more elevated, but below the melting point of the electrode wire. In some applications, it is believed that initiation of welding arcs and welds is facilitated when the electrode is hot. However, the current state of the art does not provide regimes designed to ensure that the electrode is heated prior to initiation of a welding operation.
The figures are not to scale. Where appropriate, the same or similar reference numerals are used in the figures to refer to similar or identical elements.

Systems, methods, and apparatus to preheat welding wire


A fuel cell system (1) which includes: a fuel cell (2) to be supplied with a gas for power generation, the gas unused for the power generation to be discharged out of the fuel cell (2); a circulation flow path (8) through which the discharged gas is resupplied to the fuel cell (2); a variable flow rate circulation pump (6) for circulating the gas through the circulation flow path (8); a valve (7) for discharging the gas in the circulation flow path (8) to the outside thereof; a voltage sensor (22) for measuring voltage of the fuel cell (2); and a controller (32) for controlling the circulation pump (6) and the valve (7). The circulation pump (6) and the valve (7) are controlled based on the voltage (CV) measured by the voltage sensor (22).

A fuel cell is an electrochemical device to convert chemical energy of fuel gas such as hydrogen gas and oxidant gas containing oxygen supplied thereto, directly to electric energy which is extracted from electrodes provided on both sides of an electrolyte thereof. A fuel cell using a solid polymer electrolyte membrane has low operation temperature and can be easily handled, and therefore, it has been a focus of attention as a power source for an electric vehicle.
The solid polymer electrolyte membrane is required to be retained in a moderately humidified state in order to exert oxidant gas or the both gases are humidified to be supplied to the fuel cell. Thus, water added for the humidification and water produced by a power generation reaction in the fuel cell are condensed and may cause clogging or blocking of a gas passage in the fuel cell, depending on operating conditions of the fuel cell.
Moreover, in a fuel cell using air as the oxidant gas, nitrogen contained in the air passes through a solid polymer membrane thereof, and accumulates in a fuel gas circulation system. Consequently, a fuel gas partial pressure decreases at a fuel electrode of the fuel cell, lowering operation efficiency thereof. In order to resolve the clogging and the accumulation of nitrogen, purging is performed for the fuel gas circulation system.
Japanese Patent Laid-Open Publication No. 2002-243417 discloses a fuel cell system which removes impurities accumulated in a hydrogen gas circulation system by opening a purge valve provided in the system and releasing anode off-gas to outside of the system.


A method for increasing the rate of healing in mammalian tissue includes the administration of a solution of angiotensin II.

A wound (i.e., a laceration or opening) in mammalian tissue results in tissue disruption and coagulation of the microvasculature at the wound face, and repair of such tissue represents an orderly, controlled cellular response to injury.
Tissue growth and repair are biologic systems where cellular proliferation and angiogenesis occur in the presence of an oxygen gradient. Wound healing represents an orderly, controlled cellular response to injury. The sequential morphologic and structural changes which occur during tissue repair have been characterized in great detail and have in some instances been quantified. Raftery, A. T., "Regeneration of Parietal and Visceral Peritoneum", Brit. J. Surg., Vol. 60, p. 293 (1973). All soft tissue wounds, regardless of size, heal in a similar manner. Injury results in tissue disruption and coagulation of the microvasculature at the edge of the wound. The cellular morphology consists of three distinct zones. The central avascular wound space is oxygen-deficient, acidotic, hypercarbic, and has high lactate levels. Adjacent to the wound space is a gradient zone of local anemia (ischemia) which is populated by dividing fibroblasts. Behind the leading zone is an area of active collagen synthesis characterized by mature fibroblasts and numerous newly-formed capillaries (i.e., neovascularization). While this new blood vessel growth (angiogenesis) is necessary for the healing of wound tissue, angiogenic agents have heretofore been unable to fulfill the long-felt need of providing the additional biosynthetic effects of tissue repair.
Despite the need for more rapid healing of wounds, i.e., severe burns, surgical incisions, lacerations and other trauma, there is presently no practical way to accelerate wound healing with pharmacological agents.
The invention comprises a method for increasing the rate of healing of wound tissue, comprising the application to such tissue of angiotensin II in an amount which is sufficient for said increase. As explained in the detailed description which follows, it has been found that the application of angiotensin II to wound tissue significantly increases the rate of wound healing, leading to a more rapid re-epithelialization and tissue repair.
The term angiotensin II refers to the octapeptide present in humans and other species, and has the sequence Asp-Arg-Val-Tyr-Ile-His-Pro-Phe. Angiotensin II is a known pressor agent and is commercially available.


A headrest for a vehicle seat includes a stationary support part, and an impact element which can be moved relative to the latter. The impact element is mounted on the support part via a lever system which can be at least partially decoupled, so that it permits different sequences of movement between impact element and the support part.

This application is a National Phase of PCT/EP2004/011095, filed Oct. 5, 2004, and claims the priority of German patent document DE 103 48 939.8, filed Oct. 18, 2003, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to a headrest for a vehicle seat, with a stationary support part and an impact element which can be moved relative to the latter.
A known headrest of the generic type disclosed in German patent document DE 102 02 598 A1 has a stationary support part and an impact element which can be moved relative to the latter. The two are connected to each other via upper and lower levers which form four-bar linkages. The impact element can be moved relative to the stationary support part by pivoting the levers so as to actuate the four-bar linkage. Such pivoting of the impact element relative to the stationary support part occurs in two different situations. First, by pulling the impact element forward, a desired comfortable distance can be set between head and headrest. A locking device locks the four-bar linkages, and keeps the impact element in position once it is set. Second, such moving can also be induced by a crash, via the four-bar linkage as described previously. While the adjustment for comfort purposes is carried out manually, the crash-active adjustment is performed by a drive unit.
One object of the present invention is provides an improved headrest for a vehicle seat with a stationary support part and an impact element that can be moved relative to the latter.
Another object of the invention is to provide such a headrest which is simple and can be manufactured cost effectively.
These and other objects and advantages are achieved by the headrest configuration according to the invention, in which a lever system provided between the impact element and support part can be at least partially decoupled, so that different sequences of movement are possible between the support part and impact element, depending on the reason for which such a movement takes place. Such independence of movement makes it possible to set each sequence of movement separately, and thus to provide an ideal sequence of movement for each triggering situation. In addition, the provision of two different locking systems is unnecessary.
According to one embodiment of the invention, the impact element is mounted on the support part via at least one lower lever and one upper lever. The connection via two levers constitutes a simple lever system which can be made sufficiently robust to absorb forces acting on the impact element during an accident.
It is also possible to provide a pair of levers at the bottom and top, which makes the mounting of the movable impact element more stable. The use of pairs of levers therefore supports a robust and reliable mounting of the impact element on the stationary support component. The upper and lower levers can be mounted pivotably in each case both on the stationary support part and on the movable impact element, so that they form a four-bar linkage in each case.
In still another embodiment, a hinge point of the four-bar linkage is mounted displaceably, so that the four-bar linkage can be decoupled, so as to permit different sequences of movement via the same lever arrangement. If the displaceably mounted hinge point of the four-bar linkage is locked, the sequence of movement is characterized by a pivoting of the levers about the four-bar linkages, so that the movement of the impact element relative to the stationary support part is distinguished by a combination of a pivoting movement with a translation movement. Depending in each case on the arrangement of the levers, the impact element can thereby be displaced forward (i.e., toward the vehicle occupant's head), and also downward or upward. When the displaceably mounted hinge point of the four-bar linkage is unlocked, a different sequence of movement becomes possible, which is distinguished by pivoting of at least one lever with the impact plate about a hinge point. This type of movement makes it possible to set both the distance of the impact element from a vehicle occupant's head and the inclination of the impact element.
The displaceably mounted hinge point can be a bolt which is mounted in an elongated hole, and can be pressed into the elongated hole, so as to lock the hinge point in the mounting. As a result, the elongated hole achieves a defined frictional value against the bolt. In order to adjust the hinge point in the elongated hole, a minimum force must first be overcome. This arrangement has the advantage that it can be produced in a simple and material-saving manner. It constitutes a simple possibility of locking a hinge point in a mounting.
The different sequences for moving the impact element in different situations include, for example, transfer of the impact element from a normal position into a protective position in the event of an accident, in order to protect the vehicle occupant against injuries. The protective position is defined in such a manner that it prevents a vehicle occupant's head from swinging back in the event of an accident, and therefore prevents injuries.
The transfer from the normal position into the protective position can take place via the four-bar linkage. Pivoting via the four-bar linkage has the advantage that a reliable and specifically predeterminable displacement of the impact element relative to the stationary support part is possible.
According to a further embodiment, the impact element can be adjusted in its normal position for comfort reasons. In this case, the adjustment can take place by via the decoupled four-bar linkage. For example, the comfort adjustment can take place via a movement of the displaceably mounted hinge point of the four-bar linkage.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.


A speaker comprising a frame; a first magnetic body and a second magnetic body each coupled to the frame and spaced apart by a predetermined distance from each other to form a gap, wherein the first magnetic body and the second magnetic body are arranged such that opposite polarities of the first magnetic body and the second magnetic body are provided at adjacent lateral positions; a first diaphragm; a second diaphragm; and a first voice coil plate having at least one voice coil wound on and coupled to the voice coil plate, the first voice coil plate being located in the gap between the opposite polarities of the first magnetic body and the second magnetic body, wherein the first voice coil plate is coupled to the first diaphragm and second diaphragm.

Conventional cone-type speakers usually have a cylindrical shape and use a cylindrical permanent magnet. However, such a structure results in the speaker having a substantial thickness which is not conducive to the current trend of miniaturization of electronics. Furthermore, if sound is required to be produced in more than one direction, two different speakers are often used together, which results in an unwieldy speaker system. There exists a need to produce a more compact speaker, and in particular, a bidirectional speaker capable of producing sound in two directions.


A green or sustainable building infrastructure comprising conjoining modular building segments. The purpose of the invention is to increase the precision, quality, and timing of building projects by allowing modular building segments to be constructed in an off-site controlled environment, transported, and quickly assembled on site. The conjoining modular building segments are prismatic box-like structures conjoined in a variety of configurations, each having at least three walls. The prismatic box-like structures are arranged and attached horizontally to create ceilings and floors, and they are arranged and attached vertically to create walls for the infrastructure. Some of the walls may be removed and the space inside each prismatic box-like structure is available for storage. The prismatic box-like structures may have certain dimensions, comprise specific materials, or be constructed or conjoined in specific ways.

Constructing a green or sustainable building or another structure is a complex process that requires significant amounts of time, resources, and collaboration from many fields of endeavor. Through the years, different techniques have been developed to try to maximize the efficiency and economy of the process. The most common current building techniques involve the use of standardized building components that are shipped to the construction site in small pieces and assembled on site.
However, when such methods are used, a green or sustainable building or other structure can take months or even years to build. The building project is consequently subjected to unpredictable weather conditions, and great exertions must be made to store and protect tools and resources. Resources may be wasted. Furthermore, even though efficient modern assembly techniques have driven down prices for many industrial and consumer products—such as cars, machinery, clothing, and electronics—such techniques are not fully taken advantage of in constructing green or sustainable buildings. Overall, the current methods lose the potential benefits of quality, precision, efficiency, and optimal timing that are possible through the manufacture of modular building segments in a controlled environment as described herein.
In view of the foregoing, what is needed is a green or sustainable and efficient building design that will allow the main infrastructure of a building or another structure to be manufactured in a controlled off-site environment and then be transported to a building site and quickly assembled on site to form the finished building or other structure. Such a technique would need to preserve or improve the structural integrity of the building, use efficient building techniques, provide for efficient temperature control and access to utilities within the building, and optimize the use of resources by integrating the infrastructure into the overall functionality of the building. Furthermore, unlike current modular green or sustainable building systems, such a building design should allow for an infinite variety of configurations to appeal to myriad preferences and needs.

Modular prismatic box-like structure-based building method and infrastructure


An optical transmission system is provided in which a plurality of Raman amplifiers are combined so that the wavelength band of a first Raman amplifier in the form of an upward convex curve including the maximum gain value and the wavelength band of a second Raman amplifier in the form of a downward convex curve including the minimum gain value overlap with each other, and that the wavelength band of the first Raman amplifier in the form of a downward convex curve including the minimum gain value and the wavelength band of the second Raman amplifier in the form of an upward convex curve including the maximum gain value overlap with each other. This arrangement also applies to cases where three or more amplifiers are used. Due to this arrangement, an optical transmission system is realized in which it is possible to attain a reduction in Raman gain flatness without using any means such as an equalizer.

1. Field of the Invention
The present invention relates to an improvement of gain flatness of a Raman amplifier using a wavelength multiplexed pump light source in a wavelength-division multiplexing transmission system.
2. Description of the Related Art
An optical fiber using silica as its main component and containing germanium in its core is widely used. It is known that, in a Raman amplifier using this optical fiber, maximum Raman gain value is obtained at a wavelength spaced apart by approximately 100 nm to the long wavelength side from the pump light source wavelength. An attempt has been made, utilizing this phenomenon, to amplify a wavelength-division multiplexing signal (hereinafter referred to as WDM signal) using a plurality of light sources of different wavelengths (hereinafter referred to as wavelength multiplexed pump light sources). To prevent pump lightwave on the longest wavelength side of the wavelength multiplexed pump light source from overlapping signal lightwaves on the shortest wavelength side of the WDM signal, it is necessary for the maximum wavelength band of the wavelength multiplexed pump light source to be approximately 100 nm.
Japanese Patent Application Laid-open No. 2000-98433 discloses that it is necessary to improve the flattening of the Raman gain wavelength property over a wide band in order to effect wavelength-division multiplexing transmission of signal lightwaves, and that it is necessary to take into account the wavelength arrangement of the wavelength multiplexed pump light source.
More specifically, regarding the arrangement of a plurality of pump light sources of different wavelengths, when the wavelength interval between adjacent pump lightwaves is less than 6 nm, it is impossible to secure a margin obtained by adding the band width of a combiner which does not involve an increase in the insertion loss of the combiner due to crosstalk of the combiner when combining pump lightwaves of different wavelengths to the band width of the pump light source. When the wavelength interval exceeds 35 nm, a reduction in gain which is so great as to be unsuitable for wavelength-division multiplexing transmission occurs near the center of the total Raman gain band width of the respective Raman gains generated from adjacent wavelengths, so that it is necessary for the wavelength interval of the pump lightwave to be in the range of 6 nm to 35 nm.
Further, there has been disclosed a technique in which, in order to make the wavelength interval of adjacent pump light sources as small as possible so that the total gain flatness may not increase, the pump lightwave is divided into lightwaves for forward pump and lightwaves for backward pump; for example, the pump light wavelength interval respectively belonging to the forward pump and backward pump is approximately 6 nm, and pump light wavelengths xcex2, xcex4, . . . respectively belonging to the backward pump are arranged between pump light wavelengths xcex1, xcex3, . . . belonging to the forward pump, whereby the pump light wavelength interval of the Raman amplifier is made less than 6 nm to realize a dense pump light wavelength arrangement, making it possible to realize a Raman amplifier so that the difference between maximum and minimum of the Raman gain wavelength property of the Raman amplifier, that is, the gain flatness is so small as to allow dense WDM transmission.
In the Raman amplifier disclosed in Japanese Patent Application Laid-open No. 2000-98433, forward pump and backward pump are treated independently; assuming that the combining position of forward pump lightwave is A and that the combining position of backward pump lightwave is B, the longitudinal section Axe2x86x92B of the optical fiber where stimulated Raman scattering is generated by the forward pump lightwave and the longitudinal section Bxe2x86x92A of the optical fiber where stimulated Raman scattering is generated by the backward pump lightwave are common to each other except for the pump direction.
That is, in the invention as disclosed in Japanese Patent Application Laid-open No. 2000-98433, an amplifier is formed so that gain flatness is so small as to allow dense WDM transmission by using a forward pump light source and a backward pump light source, Raman amplification being effected in the same section in the optical transmission system.
However, any practical Raman amplifier has a certain amount of gain deviation within the gain band even if it is the Raman amplifier with small gain flatness as disclosed in Japanese Patent Application Laid-open No.2000-98433.
That is, regarding the Raman amplifier in which forward pump and backward pump are combined with each other, even in the case of an amplifier with small gain flatness, when Raman amplifiers of the same gain wavelength property are used in a plurality of stages, the wavelength determining the maximum value of the Raman gain wavelength property and the wavelength determining the minimum value thereof are the same in each Raman amplifier, so that each time the amplification stages are passed, the maximum values and minimum values of the Raman gain wavelength property are accumulated, and the deviation of the Raman gain wavelength property increases, with the result that there is a large difference in power between the channels, resulting in a rather poor degree of flatness. For example, when inputting a WDM signal to an optical amplifier using an erbium doped optical fiber (EDF), or after outputting it from the optical amplifier, it is necessary to compensate for the power for each channel by a means like an equalizer.
According to a first aspect of the present invention, there is provided an optical transmission system characterized in that: a plurality of Raman amplifiers including a plurality of pump light sources of different pump wavelengths are used; the longitudinal section of the optical fiber where stimulated Raman scattering is generated differs depending upon the plurality of Raman amplifiers; and the plurality of Raman amplifiers mutually compensate for the respective Raman gain wavelength properties.
That is, according to the first aspect of the present invention, there is provided an optical transmission system in which, at an output point for a wavelength division multiplexing signal of the optical transmission system using a plurality of stages of Raman amplifiers, the total Raman gain flatness of the plurality of Raman amplifiers smaller than the cumulative flatness on the assumption that every amplifier has the same gain profile of one of the plurality of Raman amplifier.
According to a second aspect of the present invention, in the first aspect of the invention, there is provided an optical transmission system characterized in that the plurality of Raman amplifiers are designed to be of at least two types of pump wavelength sets, and when there exist a plurality of Raman amplifiers of the same pump wavelengths which use the same kind of amplifier fibers, they include different set gains.
According to a third aspect of the present invention, in the first or second aspect of the invention, there is provided an optical transmission system characterized in that: at least a first Raman amplifier and a second Raman amplifier are used as the plurality of Raman amplifiers; a wavelength band where the Raman gain wavelength property of the first Raman amplifier exhibits an upward convex curve including a maximum value of Raman gain of GAmax at a wavelength of xcexAmax and a wavelength band where the Raman gain wavelength property of the second Raman amplifier exhibits a downward convex curve including a minimum value of Raman gain of GBmin at a wavelength of xcexBmin overlap with each other; a wavelength band where the Raman gain wavelength property of the first Raman amplifier exhibits an downward convex curve including a minimum value of Raman gain of GAmin at a wavelength of xcexAmin and a wavelength band where the Raman gain wavelength property of the second Raman amplifier exhibits an upward convex curve including a maximum value of Raman gain of GBmax at a wavelength of xcexBmax overlap with each other; and the total Raman gain flatness is smaller than the flatness of said first Raman amplifier and said second Raman amplifier.
That is, according to the third aspect of the invention, there is provided an optical transmission system in which, regarding the gain flatness of the optical transmission system using the first Raman amplifier and the second Raman amplifier, the maximum and minimum values of the respective Raman gain wavelength properties of the first Raman amplifier and the second Raman amplifier are not accumulated to cause an increase in the total Raman gain flatness, and in which the total Raman gain flatness can be set to be smaller than the gain flatness of each of the first Raman amplifier and the second Raman amplifier.
According to a fourth aspect of the present invention, in the third aspect of the invention, there is provided an optical transmission system characterized in that the wavelength xcexAmax and the wavelength xcexBmin are substantially equal to each other, and in which the wavelength xcexAmin and the wavelength xcexBmax are substantially equal to each other.
That is, according to the fourth aspect of the invention, there is provided an optical transmission system, in which the total Raman gain flatness of the optical transmission system using the first Raman amplifier and the second Raman amplifier is minimum.
According to a fifth aspect of the present invention, in any one of the first to fourth aspects of the invention, there is provided an optical transmission system characterized in that at least one of a discrete Raman amplifier and a distributed Raman amplifier is used as the Raman amplifier.
That is, according to the fifth aspect of the invention, there is provided an optical transmission system, in which discrete amplifiers or distributed amplifiers are used so that the total Raman gain flatness is smaller than the each Raman gain flatness of the plurality of Raman amplifiers constituting the optical transmission system.
For example, when laying a new line as a transmission path or when newly installing a Raman amplifier in an existing line where no Raman amplifier is used, the deviation of the gain wavelength property increases cumulatively if a large number of stages of Raman amplifiers having the same gain wavelength property are used when a large number of stages of Raman amplifiers are required, so that it is necessary to select either a discrete Raman amplifier or a distributed Raman amplifier for each Raman amplifier in order that the respective gain wavelength properties of the Raman amplifiers mutually compensate for so as to decrease the total gain flatness. When Raman amplifiers are to be added to an existing optical transmission system in which a Raman amplifier has already been installed, it is necessary to select either a discrete amplifier or a distributed amplifier for each of the additional Raman amplifiers in order that the gain wavelength property of the existing Raman amplifier and the gain wavelength property of the additional Raman amplifiers may mutually compensate for so as to decrease the total Raman gain flatness.
Here, the theory on which the present invention is based will be described.
There are two kinds of Raman amplifiers: a distributed amplifier and a discrete amplifier. In the distributed Raman amplifier, mainly the optical fiber transmission path itself is used as the medium for Raman amplification, so that, taking into account the distortion generated when, for example, amplifying the WDM signal, the optical fiber transmission path is one whose effective core area Aeff in the signal band wavelength is from approximately 50 xcexcm2 to 100 xcexcm2. It is not necessary for the actual gain of the distributed amplifier, that is, the Raman gain, to exceed the transmission loss of a relay section of the optical transmission path itself.
The discrete Raman amplifier is used as a relay amplifier, so that the effective core area Aeff in the signal band wavelength is made as small as approximately 10 xcexcm2 to 30 xcexcm2 to thereby increase the non-linearity, and, as far as the Raman gain due to the effective core area Aeff is concerned, it is so designed that the Raman gain of the discrete Raman amplifier is larger than the Raman gain of the distributed Raman amplifier by approximately 10 dB. Further, since the discrete Raman amplifier is used as a relay amplifier, a Raman gain which is in excess of the transmission loss of the highly non-linear optical fiber constituting the discrete Raman amplifier is required. That is, the gain of the discrete Raman amplifier must be a net gain, which is an apparent gain.
In the case of signal/wavelength and pump lightwave/wavelength, the Raman gain is approximately given as: G=exp(gRPOLeff/Aeff), where gR is the Raman gain coefficient; PO is the pump light power at the pump light input end of the optical fiber constituting the Raman amplifier; and Leff is the length (effective length) generating effective stimulated Raman effect. Assuming that xcex1p is the attenuation per unit length of the pump lightwave, Leff=(1/xcex1p)[1xe2x88x92exp(xe2x88x92xcex1pL)]. L is the length of the longitudinal section of the optical fiber where stimulated Raman scattering is generated by the Raman amplifier.
Thus, to experimentally obtain a Raman gain coefficient belonging to a desired wavelength band, a pump lightwave in which the pump light wavelength xcexp is fixed to the shortest wavelength side of the desired wavelength band is input to the pump light input end of the optical fiber constituting the Raman amplifier, and the signal light wavelength xcexs is swept from the short wavelength side to the long wavelength side of the desired wavelength band, measuring the pump light power PO at the pump light input end of the optical fiber constituting the Raman amplifier and the input end signal lightwaves input P1 and the output end signal lightwave output P2 of the Raman amplifier.
In correspondence with the fixed pump light wavelength xcexp and the swept signal light wavelength xcexs, the apparent gain (net gain) GN=10 log(P2/P1) is obtained from the input end signal lightwaves input P1 and the output end signal lightwaves output P2, and the signal light transmission loss xcex1gL which is the product of the attenuation xcex1s per unit length in the signal light wavelength of the optical fiber constituting the Raman amplifier by the length L of the optical fiber constituting the Raman amplifier, obtaining the actual gain (Raman gain) G from the equation: G=Gn+xcex1sL.
The pump light power PO at the pump light input end of the optical fiber constituting the Raman amplifier can be measured, and, since the length L of the optical fiber constituting the Raman amplifier is known, Leff can be obtained through calculation. Since the gain G has been obtained, gR/Aeff can be obtained from the equation: G=exp(gRPOLeff/Aeff), and since Aeff is known by a well-known experiment method, gR can be obtained. For gR to be clearly measured, it is necessary for the pump light power PO at the pump light input end of the optical fiber constituting the Raman amplifier to be approximately +10 dBm, and the signal lightwaves is required to be approximately xe2x88x9220 dBm.
Assuming that "ugr"p is the frequency corresponding to the pump light wavelength xcexp and that "ugr"s is the frequency corresponding to the signal light wavelength xcexs, the above-mentioned Raman gain coefficient gR("ugr"p, "ugr"s) is obtained with respect to the parameters ("ugr"p, "ugr"s) of the fixed pump light frequency "ugr"p and the signal frequency "ugr"s of the signal to be swept. It is theoretically known that the generalized Raman gain coefficient gR depends upon the frequency shift xcex94"ugr"="ugr"pxe2x88x92"ugr"s. Thus, in order to obtain the generalized Raman gain coefficient gR(xcex94"ugr"), gR(xcex94"ugr") of the same magnitude is brought into correspondence with gR("ugr"p, "ugr"s) corresponding to the parameters ("ugr"p, "ugr"s), and the parameters ("ugr"p, "ugr"s) are replaced by the frequency shift xcex94"ugr"="ugr"pxe2x88x92"ugr"s.
In this way, the wavelength (frequency) dependency of the generalized Raman gain coefficient (or gR/Aeff) is obtained to prepare a table of wavelength (frequency)/Raman gain coefficient (or gR/Aeff).
The basic idea regarding the way pump lightwave, signal lightwaves, and optical fiber attenuation are related with each other in Raman amplification is described in xe2x80x9cPump Interactions in a 100 nm Bandwidth Raman Amplifierxe2x80x9d IEEE PHOTONICS TECHNOLOGY LETTERS, VOL.11, No. 5, MAY 1999, p.530.
Based on this idea, a basic equation showing how pump as lightwave, signal lightwaves, and optical fiber attenuation for Raman amplifier simulation are related was obtained on the assumption that the pump lightwave and signal lightwaves advance, that Rayleigh scattering is small, and that the influence of spontaneous emission light is negligible.
Assuming that the optical fiber attenuation at frequency "ugr" is xcex1"ugr", that the effective core area is Aeff"ugr", and that the Raman gain coefficient between frequency "xgr" and frequency "ugr" is gR("xgr"xe2x88x92"ugr")=g"xgr""ugr", the change in power at the time when advancing wave of power P"ugr" at frequency "ugr" has advanced by distance Z is expressed by the following equation:                                           ⅆ                          P              v                                            ⅆ            z                          =                                            -                              α                v                                                                P              v                                +                                    P              v                                                                  ∫                                  c                   greater than                   v                                                                                g                    cv                                                        A                                          eff                                                                    xe2x80x83                                                                                                                                                  P                                                                                    ⅆ                                                                                -                                    P              v                                                                  ∫                                  c                   less than                   v                                                                                g                                          v                                                                    xe2x80x83                                                                                                                                              A                    effv                                                                                P                                                                                    ⅆ                                                                                                  Equation                          xe2x80x83                        1
It is assumed here that the powers of WDM signals at frequencies "ugr"1, "ugr"2, . . . , "ugr"n are Ps"ugr"1, Ps"ugr"2, . . . , Ps"ugr"n, that the powers of multiplexing pump lightwaves at frequencies "xgr"1, "xgr"2, . . . , "xgr"m are Pp"xgr"1, Pp"xgr"2, . . . , Pp"xgr"m ("ugr"1 less than "ugr"2 less than . . .  less than "ugr"n less than "xgr"1 less than "xgr"2 less than . . .  less than "xgr"m), and that there is no Raman transition between the WDM signals.
As stated above, both WDM signal and pump lightwave are discrete spectrums, so that the integration of equation 1 is replaced by addition.
By applying a WDM signal of a frequency "ugr"k and power Ps"ugr"k to P"ugr"of equation 1, the following equation is obtained:                                           ⅆ                          P              svk                                            ⅆ            z                          =                                            -                              α                vk                                                                P              svk                                +                                    P              svk                                                                  ∑                1                gn                                                          xe2x80x83                                                                                g                                                                                                              xe2x80x83                                                                  vk                                                                            A                                          eff                                                                    xe2x80x83                                                                                                                                                  P                                      p                                                              xe2x80x83                                                                                                                                            Equation                          xe2x80x83                        2
Further, by applying a pump lightwave of a frequency "xgr"j and power PP"xgr"j to P"ugr"of equation 1, the following equation is obtained:                                           ⅆ                          P              pq                                            ⅆ            z                          =                                            -                              o                ci                                                                P              rcj                                +                                    P              pcj                                                                  ∑                1                gn                                                          xe2x80x83                                                                                g                                                                                                              xe2x80x83                                                                  ci                                                                            A                                          eff                                                                    xe2x80x83                                                                                                                                                  P                                      p                                                              xe2x80x83                                                                                                                                            -                                    P              pci                                                                  ∑                1                                                      ς                                                              xe2x80x83                                                            i                                    -                  1                                                                          xe2x80x83                                                                                g                                          ci                                                                    xe2x80x83                                                                                                                                              A                                          eff                                                                    xe2x80x83                                                                                                                                      xe2x80x83                                                                  i                                                                                                    i                                                                                                      P                                      p                                                              xe2x80x83                                                                                                                                            -                                    P              pci                                                                  ∑                1                vi                                                          xe2x80x83                                                                                g                                                                                                              xe2x80x83                                                                  iv                                                                            A                                          eff                                                                    xe2x80x83                                                                                                                                      xe2x80x83                                                                  i                                                                                                    i                                    v                                                                  P                  sv                                                                                Equation                          xe2x80x83                        3
The power (Ps"ugr"1, Ps"ugr"2, . . . , Ps"ugr"n) of the WDM signal is given at the signal input point, and the multiplexing pump lightwave (Pp"xgr"1, Pp"xgr"2, . . . , Pp"xgr"m) is given at the pump lightwave input point, so that the following results are achieved in the cases of forward pump, backward pump, and a combination of both.
First, the case of forward pump will be described. By substituting the initial value set when Z=0(Ps"ugr"1, Ps"ugr"2, . . . , Ps"ugr"n) and (Pp"xgr"1, Pp"xgr"2, . . . , Pp"xgr"m), respectively into the right side of equation 2 and equation 3, xcex94Ps"ugr"k and xcex94Pp"xgr"j spaced apart from Ps"ugr"k and Pp"xgr"j by xcex94z with respect to arbitrary "ugr"k and arbitrary "xgr"j are obtained. By substituting Ps"ugr"k+xcex94Ps"ugr"k and Pp"xgr"j+xcex94Pp"xgr"j respectively into the right sides of equation 2 and equation 3 as Ps"ugr"k and Pp"xgr"j, it is possible to obtain Ps"ugr"k and Pp"xgr"j spaced apart from the point where z=0 by 2xcex94z. By repeating this, it is possible to obtain (Ps"ugr"1, Ps"ugr"2, . . . , Ps"ugr"n) and (Pp"xgr"1, Pp"xgr"2, . . . , Pp"xgr"m) at the output point. Thus, the gain is known.
Next, the case of backward pump will be described. It is assumed that multiplexing pump lightwave (Pp"xgr"1, Pp"xgr"2, . . . , Pp"xgr"m) is subjected to backward pump when Z=L, and that the anticipated value of multiplexing pump light power when Z=0 is Pp"xgr"kxe2x88x92xcex1"xgr"kL (k is an integer ranging from 1 to m), taking into account the transmission loss xcex1"xgr"k. The initial value of the WDM signal lightwaves (Ps"ugr"1, Ps"ugr"2, . . . , Ps"ugr"n) when Z=0 and the anticipated value of multiplexing pump light power are computed in the same manner as in the case of forward pump. In this process, equation 2 is used as it is, and, regarding equation 3, + sign and xe2x88x92 sign are exchanged, obtaining the multiplexing pump light power (Pp"xgr"1, Pp"xgr"2, . . . , Pp"xgr"m) when Z=L. When the computed multiplexing pump light power and the set multiplexing pump light power coincide with each other within the set error range, the computed WDM signal lightwaves (Ps"ugr"1, Ps"ugr"2, . . . , Ps"ugr"n) when Z=L is adopted as a solution satisfying equation 2 and a solution satisfying the equation in which the signs of equation 3 are exchanged. When the computed multiplexing pump light power and the set multiplexing pump light power are outside the set error range, the magnitude of the multiplexing pump light power (Pp"xgr"1, Pp"xgr"2, . . . , Pp"xgr"m) when Z=0 is anticipated and set anew, and the initial value of the WDM signal lightwaves (Ps"ugr"1, Ps"ugr"2, Ps"ugr"n) when Z=0 and the anticipated set value of the multiplexing pump light power are, as in the case of forward pump, substituted into equation 2 and the equation obtained by exchanging the signs of equation 3, obtaining the multiplexing pump light power (Pp"xgr"1, Pp"xgr"2, . . . , Pp"xgr"m) when Z=L. The above computation is repeated until the computed multiplexing pump light power when Z=L and the set multiplexing pump light power coincide with each other within the set error range.
Next, the case of a combination of forward pump and backward pump will be described. Here, it is assumed there is no mutual action between forward pump and backward pump. Thus, superposition of forward pump and backward pump is performed to obtain gain. That is, the sum of equation 3 indicating the pump lightwave at the time of forward pump and an equation obtained by exchanging the signs of equation 3 indicating the pump lightwave at the time of backward pump is substituted into the Pp"xgr" of equation 2 indicating the pump lightwave, repeating the algorithm for forward pump and backward pump.
As in the above three cases, simulation is performed using equation 2 and equation 3, the gain wavelength properties of two Raman amplifiers compensate for each other, and a value at which the total Raman gain flatness is decreased is searched for. By applying the value to an actual system, it is possible to realize the optical transmission system of the present invention.


In one aspect, rotary cutting tools are described comprising clearances with projections adjacent the cutting edge and extending the width and length of the clearance surface of each tooth. This design can assist in reducing vibration or chatter during cutting operations.

Solid end mills, especially with cutting diameters equal and larger than 12 mm, implemented with currently well-known straight and eccentric clearances (or combination of both), when applied to cutting metals, tend to generate, sometimes considerable, vibrations (or chatter). Suppressing vibrations is one of most essential requirements to any solid end mill. Therefore, there is a huge effort to develop and pro-duce special geometry features helping to reduce or eliminate chatter.
By implementing end mills with an unequal index, deferential helix angles, veritable helix angles, and the like, the problem partially gets solved. For example, some of these features might work well for titanium alloys, but does not suppress vibrations in stainless steels, or other materials. In addition, some combinations of these features provide an acceptable solution for cutting diameters up to 12 mm, but vibrations still exist at larger cutting diameters.
The so-called "micro land" is the currently existing solution to suppress vibrations for solid end mills with a cutting diameter larger than 12 mm, which is produced by grinding a tiny clearance facet of 0.05-0.1 mm width and with an angle of between 1.5-3°. The clearance facet must be ground adjacent the cutting edge. Along with high accuracy needed for grinding the land width and angles, the "micro land" requires, at least two cleanses (i.e., minimum 2 passes) on each tooth, and probably three cleanses for each tooth.
Another problem is that cutters with the "micro-land" consume considerably larger spindle power vs. cutters without the "micro-land." In fact, there is an increase in specific energy, which in turn produces larger hit generation during milling, which in turn creates additional difficulties in applying cutters with the "micro-land" to cut high temperature alloys. In view of the foregoing, improved end mills are de-sired that provide one or more advantages over conventional designs.

Solid end mill with complex clearance surface