A method and apparatus for determining the total base number of a used lubricant from an open, all loss, lubricating system. An AC voltage signal is applied between electrodes immersed in the used lubricant and a used-lubricant dependent response to the applied signal measured. The used lubricant base number is determined from the response. To allow for changes in the fresh lubricant inputted to the open lubricating system, the method and apparatus can have means for determining properties of the fresh lubricant needed to determine the total base number of used lubricant. To allow for possible contamination of the used lubricant, the method and apparatus can have means for determining the concentration of contamination and for determining properties of the contaminant needed to determine the total base number of used lubricant.

The present invention is a method and apparatus for determining remaining basicity of a used cylinder lubricant from an open, also referred to as an all-loss, lubrication system. The present invention has benefit in providing a near real-time basicity estimate of the used lubricant from an open power-cylinder lubricating system of a slow-speed, two-stroke diesel engine of crosshead construction.
Slow-speed, two-stroke diesel engines of crosshead construction are used in marine propulsion, stationary power or other applications because of their efficient, high power output. Unlike a smaller four-stroke engine with a single closed lubricating system that continuously circulates lubricant from a reservoir, often referred to as a sump, to the engine components and back to the reservoir, the crosshead two-stroke engine has two lubricating systems, a closed recirculating system that lubricates and protect the surfaces in the crankcase, and an open system that applies a cylinder lubricant only once to lubricate and protect the power cylinder walls and pistons before the used lubricant is removed from the engine and discarded.
A major reason for using an open cylinder lubricating system is that sulfur content of fuel for slow-speed crosshead engines is typically in the range of 1.5 to 5.0%. This compares to fuel sulfur content of typically less than 0.05% for most medium and high speed diesel engines. Since sulfur reacts to form acids, especially during the combustion process, the higher sulfur content fuel results in higher acid content in the engine cylinders. If the acids formed during combustion are not effectively neutralized, they can attack engine surfaces to cause reduced engine performance and life. Lubricant used on internal-combustion-engine cylinder walls should, as one of is functionalities, neutralize acids. This neutralizing functionality is achieved by formulating the lubricant to have high alkalinity, that is, to be highly basic. A lubricants' alkalinity is described by a Total Base Number (TBN), often referred to as the lubricant's Base Number (BN), which is a measure of the amount of acid that a mass of lubricant can neutralized. TBN is reported in terms of milligrams of potassium hydroxide per gram (mg KOH/g) and is, in general, determined by either ASTM D2896 or D4739 titrations methods. The sulfur content of typical four-stroke diesel fuel is sufficiently low so that a sufficiently high TBN engine lubricant can be formulated to allow a relatively long useful life in a closed lubricating system. Lubricant useful life ends and the lubricant must be replaced when the remaining TBN reaches a limit, typically set by the engine manufacturer, below which the lubricant no longer provides the desired acid neutralization function. With the high sulfur content of slow-speed crosshead diesel engine fuel, a lubricant has not been formulated to have a long service life in a closed lubricating system; hence an open lubricating system should be used.
To provide desired engine performance and life at an acceptable cost, the formulation and flow rate of a lubricant in an open cylinder lubricating system needs to be optimized. The lubricant flow rate should be selected to be sufficiently high for a particular engine operating condition to provide a lubricating film to minimize friction between piston rings and cylinder walls, and the lubricant must be formulated so that at a selected flow rate and operating condition and at a given fuel sulfur content, there is an appropriate basicity to adequately neutralize acids entering the lubricant from the combustion process without having excess basicity that can cause piston ring deposits and ultimately ring and cylinder wall wear. Appropriate basicity is typically determined by the remaining TBN of the used cylinder lubricant that is removed from a cylinder.
Traditionally, the optimization of lubricant flow rate and formulation is done by selecting a lubricant with an appropriate TBN for an expected range of fuel sulfur contents and varying lubricant flow rate to the cylinders based on a table or formula that uses the actual sulfur content reported by the fuel supplier, the operating condition/state of the engine, and historic off-line TBN analyses of used cylinder lubricants. The TBN analyses are typically laboratory methods performed on samples removed from individual cylinders for known fuel sulfur content and operating conditions. A problem with this traditional optimization method is that the current flow rate decision is made based on historic TBN data and not real-time or near real-time data. Hence, flow rates are, in general, conservatively set higher than needed so as to protect against, for example, transient or incorrectly reported fuel sulfur content. While a too high flow rate is better than the consequences of having a too low flow rate, a too high flow rate results in added lubricant costs and can potentially lead to piston ring deposits.
To minimize both risks and costs, engine operators desire to know the remaining TBN in the used cylinder lubricant in either real-time or near real-time to set an appropriate lubricant flow rate. Methods that use acid reagents to measure or estimate TBN, such as the ASTM methods, are too complex in most engine applications to be accurately and/or quickly performed. Methods that use Infrared (IR) Spectroscopy to measure one or more oxidation peaks of the used lubricant, for example the method described in Reischman et al. U.S. Patent Application 2003/0164451, currently estimate TBN by near real-time methods. An issue with IR TBN sensors is that due to the relatively opaque nature of used cylinder lubricant the sensor must have a relatively narrow gap if a transmission technique is used or must use an Attenuated Total Reflectance (ATR) technique. A narrow gap of a transmission IR sensor can get blocked over long periods with the relatively high viscosity used lubricant, and a surface of an Internal Reflection Element (IRE) of an ATR IR sensor can get coated over long periods with the relatively high viscosity, surface active used lubricant. When used in situ for essentially real-time TBN estimates, IR sensors typically require periodic cleaning to assure accurate long-term results.
Another issue when determining the remaining TBN of a used cylinder lubricant is that the used lubricant can be contaminated by the system lubricant in the closed lubrication system that lubricates the engine's crankcase components. The crosshead construction of two-stroke engines has a diaphragm and stuffing boxes separating the power cylinders from the crankcase to prevent combustion by-products and cylinder lubricant from entering the crankcase and conversely to prevent crankcase lubricant from entering the cylinder and mixing with the used cylinder lubricant before removal from the engine. The diaphragm and stuffing boxes, however, are typically not 100% efficient and, in general, the efficiency decreases with engine use such that the lubricant removed from the power cylinders may be a mixture of used cylinder lubricant and crankcase lubricant with the ratio of the two lubricants varying with engine operating conditions. Hence, the measured TBN may not accurately represent the TBN of the used cylinder lubricant.
Therefore, there remains a need for a reliable, accurate method and apparatus for real-time or near real-time estimation of used cylinder-lubricant remaining TBN over long periods of use. Accordingly the present invention is a method that meets that need.

Method and apparatus for estimating basicity of a used, all-loss cylinder lubricant


N-channel MOS transistors are connected to bit lines so as to correspond to the data to be read out. A constant current outputting circuit uses an off leakage current of load transistors similar to the N-channel MOS transistors as a reference current to constitute a current mirror circuit having a mirror ratio according to the number of the N-channel MOS transistors connected to each bit line. P-channel MOS transistors of the constant current outputting circuit are connected to the bit lines and supply a current according to the off leakage currents of the N-channel MOS transistors. Thus, malfunctions caused by such as off leakage currents of transistors or the like can be reliably prevented without causing an increase in access time.

1. Field of the Invention
The present invention relates to a technology pertaining to a bit line precharge-type semiconductor read only memory.
2. Description of the Related Art
Conventionally, a bit line precharge-type read only memory has been used in which data are stored according to whether or not there is a transistor connected to a bit line and the stored data are read out by detecting the potential of the bit line that has been precharged. Specifically, this type of read only memory has such a configuration as shown in FIG. 9.
As seen in the figure, precharge transistors Tr810 to Tr8n0, which constitutes a precharge circuit, are so configured as to precharge bit lines B810 to B8n0 under the control of a precharge signal 800.
Word lines W801 to W80m are respectively connected to the gates of N-channel MOS transistors Tr811 to Tr8nm, which constitute columns of transistors. More specifically, for example, the word line W801 is connected to the gates of the N-channel MOS transistors Tr811 to Tr8n1, the word line W802 is connected to the gates of the N-channel MOS transistors Tr812 to Tr8n2, and the word line W80m is connected to the gates of the N-channel MOS transistors Tr81m to Tr8nm.
The sources of the N-channel MOS transistors Tr811, etc. are grounded, whereas the drains are either connected to or cut off from the corresponding bit lines B810 to B8n0 according to the data (xe2x80x9c0xe2x80x9d or xe2x80x9c1xe2x80x9d) to be recorded, Specifically, in the example shown in the figure, drains of N-channel MOS transistors Tr811, etc. are connected to the bit lines B110, etc. in the cases where data to be recorded are xe2x80x9c0xe2x80x9d. Accordingly, when these N-channel MOS transistors, Tr811, etc. are tuned ON during read-out, the potentials of the bit lines B810, etc. to which the drains of the N-channel MOS transistors Tr811, etc. are connected are changed to a low level (xe2x80x9cLxe2x80x9d level).
P-channel MOS transistors Tr911 to Tr9n1 constitute pull-up circuits, and the drive capability of each of these P-channel MOS transistors is determined so that when data xe2x80x9c1xe2x80x9d is read out (i.e., when the drains of the N-channel MOS transistors Tr812, etc. that are turned ON are not connected to the bit lines B810, etc.), the potentials of the bit lines B810 to B8n0 are maintained at a high level (xe2x80x9cHxe2x80x9d level), and that the drive capability is less than that of the N-channel MOS transistors Tr811, etc.
The bit lines B810 to B8n0 are respectively connected to inverter circuits Inv811 and Inv812 to Inv8n1 and Inv8n2, which constitute output circuits.
In the read only memory as described above, data are read out according to the following operation.
(1) First, as shown in FIG. 10, the precharge signal 800 is reduced to an xe2x80x9cLxe2x80x9d level, the precharge transistors Tr810, etc. are switched to an ON state, and each of the bit lines B810 are precharged to an xe2x80x9c1xe2x80x9d level.
(2) Thereafter, in response to an input address signal (not shown), one of the word lines W801, etc. is selected and turns to an xe2x80x9cHxe2x80x9d level.
(3) Then, for example, when the word line W802 is selected and turns to an xe2x80x9cHxe2x80x9d level, the N-channel MOS transistors Tr812 to Tr8n2 that are connected to the word line W802 are switched to an ON state.
In this case, the drain of the N-channel MOS transistor Tr812 that is switched to an ON state is not connected to the bit line B810, and therefore, the potential of the bit line B810 is maintained at the xe2x80x9cHxe2x80x9d level by the P-channel MOS transistor Tr911 even after the precharge signal 800 has changed to the xe2x80x9cHxe2x80x9d level. Thus, a data xe2x80x9c1xe2x80x9d is output via the inverter circuits Inv811 and Inv812.
Meanwhile, the drain of the N-channel MOS transistor Tr822 that is also switched to an ON state is connected to the bit line B820 and, in addition, the drive capability of the P-channel MOS transistor Tr921 is made lower than the N-channel MOS transistor Tr822, as mentioned above. Therefore, the bit line B810 is discharged and the potential is reduced to an xe2x80x9cLxe2x80x9d level. Thus, a data xe2x80x9c0xe2x80x9d is output via the inverter Inv821 and Inb822.
In recent years, miniaturization has advanced in the process for CMOS semiconductor integrated circuit, and the power supply voltage has been more and more scaled as the thickness of the gate oxide film reduces. In order to avoid a operating speed reduction caused by the decrease of power supply voltage, there has been a trend toward reduction in threshold voltages of MOS transistors.
When the threshold voltage is reduced, however, the off leakage current of a MOS transistor increases. Consequently, in read only memories in which a number of drain nodes are connected to bit lines, the potentials of the bit lines tend to fluctuate, often causing device malfunctions. For example, in read only memories, the number of N-channel MOS transistors that are connected to bit lines often exceeds 1000, and therefore, even if the leakage current of each transistor is small, the total of the leakage current well exceeds a negligible level and affects circuit operation to cause malfunctions.
More specifically, assuming a case, for example, where there are a large number of the N-channel MOS transistors Tr811, etc. whose drains are connected to the bit line 810 (i.e., a case where many data xe2x80x9c0xe2x80x9ds are written), when the word line W802 turns to an xe2x80x9cHxe2x80x9d level as described above, then the potential of the bit line B810 cannot be maintained at the xe2x80x9cHxe2x80x9d level, as shown by the dashed line in FIG. 10 and results in an output data xe2x80x9c0xe2x80x9d, when the total of the off leakage currents of the N-channel MOS transistors Tr811 to Tr81m (except Tr812) exceeds the current that the pull-up circuit can supply (i.e., exceeds the drive capability), even though the drain of the N-channel MOS transistor Tr812 is not connected to the bit line B810 (i.e., even though a data xe2x80x9c1xe2x80x9d has been written therein). This phenomenon is apt to occur particularly at high temperatures, at which the off leakage current increases.
On the other hand, if the drive capability of the pull-up circuit is increased to prevent such a malfunction as described above, the discharge operation by the N-channel MOS transistor Tr822 is hindered by the pull-up circuit in the bit line B820, which is supposed to output a data xe2x80x9c0,xe2x80x9d and a time lag until the bit line B820 reaches the xe2x80x9cLxe2x80x9d level becomes long as shown by the dash-dot line in FIG. 9. This causes an increase in access time during read-out.
Moreover, as the potential of the bit line B820 is reduced by discharging, the voltage between the source and the drain of the P-channel MOS transistor Tr921 (pull-up circuit) increases, thereby increasing the current supplied to the bit line B820. As a result, the potential of the bit line B820 cannot be reduced below the threshold level of the inverter circuit Inv821, further increasing the possibility of malfunctions.
In view of the foregoing and other problems, it is an object of the present invention to reliably prevent malfunctions of read only memories caused by, for example, off leakage current of transistors without increasing access time.
This and other objects are accomplished, in accordance with a first aspect of the present invention, by providing a read only memory having a plurality of bit lines, a plurality of word lines, and a plurality of switching elements, wherein data corresponding to the presence or absence of switching elements connected to the bit lines are read out by discharging electric charge precharged in the bit lines with the switching elements selected by the word lines, the read only memory comprising: at least one current supplying circuit that supplies current to one of the bit lines when the switching elements are selected by the word lines; wherein the current supplying capability of the current supplying circuit is determined according to the number of the switching elements connected to the one of the bit lines.
With this configuration, the off leakage current of the switching elements that are not selected by the word lines is appropriately compensated sufficiently but not excessively by the current supplying circuit having a current supplying capability according to the number of the switching elements. Specifically, when the number of the switching elements connected to a bit line is large, the current supplying capability of the current supplying circuit that supplies current to the bit line is determined to be large, so that malfunctions caused by a decrease in the potential of the bit line can be prevented, whereas when the number of the switching elements connected to a bit line is small, the current supplying capability is determined to be small, so that malfunctions and operation speed degradations can be prevented that are caused by the obstruction to the discharge operation of the switching elements that are selected by word lines and are switched to an ON state.
In the above-described read only memory, the current supplying circuit may be a constant current circuit.
With this configuration, even if the potential of the bit line is reduced by the discharge of the switching elements that are selected and turned ON by the word lines, the potential of the bit line can be reliably reduced because the supplied current does not fluctuate. Specifically, in the case where a current is supplied to a bit line by a MOS transistor, as the potential of the bit line decreases, the supplied current increases since the voltage between the source and the drain of the MOS transistor increases. Therefore, the potential of the bit line cannot be sufficiently reduced, and the margins for switching levels of the output circuit tend to be small. In view of this, as described above, when a current is supplied to the bit line using a constant current circuit, the supplied current does not increase even if the potential of the bit line decreases. Thus, the potential of the bit line can be quickly and sufficiently reduced and consequently, operation speed is improved while margins of the output circuit are increased.
In the above-described read only memory, the constant current circuit may include a reference current generating circuit for generating a predetermined reference current using the same type of switching element as the switching elements; and a current mirror circuit for mirroring the reference current and supplying electric current to the bit line; wherein the mirror ratio of the current mirror circuit is determined according to the number of the switching elements.
With this configuration, since the current mirror circuit can supply a constant current that is proportional to a reference current, a constant current according to the number of the switching element connected to a bit line can be easily supplied to the bit line by appropriately determining the mirror ratio. In addition, since a current is supplied to the bit line using the current generated by a switching element of the same type as the switching element connected the bit line as a reference current, the off leakage current of the switching elements connected to the bit line can be easily compensated appropriately. Specifically, the use of a current mirror circuit makes it possible to supply a current for compensating an off leakage current, for example, using off transistors having characteristics corresponding to the transistors connected to the bit line (temperature characteristics and power supply voltage characteristics). Therefore, in comparison with conventional cases in which an on current of transistors is supplied, the accuracy of current compensation can be more easily increased without carrying out difficult matching of characteristics. Moreover, the off leakage current can be effectively cancelled against fluctuations in ambient conditions such as power supply voltages and ambient temperatures.
In the above-described read only memory, the current supplying circuit may supply an electric current to the bit line when the potential of the bit line is higher than a predetermined potential whereas the current supplying circuit may cut off electric current to the bit line when the potential of the bit line is lower than the predetermined potential.
With this configuration, the current supply is stopped when the potential of the bit line is reduced to a lower potential than a predetermined potential by the discharge of the switching elements selected by word lines and turned ON, and therefore, the potential of the bit line can be reduced more quickly and reliably thereafter. Consequently, margins in discharge operations can be increased.
In the above-described read only memory, the numbers of the switching elements to be connected to the bit lines may be categorized into a plurality of groups, and the current supplying capability of the current supplying circuit may be determined according to the groups.
With this configuration, the variety of current supplying circuits having differing current capabilities can be reduced, and therefore, simplification of the configurations can be easily achieved.
The above-described read only memory may further have a current adjusting circuit for adjusting the current supplying capability according to the potential of the bit line when all the switching element connected to the bit line are in an OFF state.
In the above-described read only memory, the current adjusting circuit may include a comparator circuit that compares the potential of the bit line with a predetermined reference potential when all the switching elements connected to the bit line are in an OFF state; a holding circuit that holds a comparison result obtained by the comparator circuit; and an adjusted current supplying circuit that supplies a current to the bit line according to the data held in the holding circuit.
With these configurations, even when the off leakage current fluctuates, for example, due to variations of the off leakage characteristics of the switching elements, a current corresponding to the fluctuating off leakage current can be supplied to the bit line by, for example, monitoring the potential of the bit line when the switching elements are in an OFF state. Therefore, a discrepancy between the off leakage current and the supplied current is suppressed and the off leakage current can be compensated more reliably.
In accordance with another aspect of the present invention, a read only memory is provided having a plurality of bit lines, a plurality of word lines, and a plurality of switching elements, wherein data corresponding to the presence or absence of switching elements connected to the bit lines are read out by discharging electric charge precharged in the bit lines with the switching elements selected by the word lines, the read only memory comprising: a plurality of current supplying portions that constitute a current supplying circuit having a predetermined current supplying capability and supplying electric current when the switching elements are selected to the word line; wherein at least one of the current supplying portions is connected to one of the bit lines according to the number of the switching elements connected to the bit line.
With this configuration, when fabricating a read only memory, current supply to the bit line is effected with current supplying capabilities according to varying write data by merely controlling the connection or the disconnection between the current supplying portions and the bit line, and the portions except the connection or the disconnection can be communized between the read only memories having different write data. Therefore, automatic design layout of the elements or the like for the read only memory is easily achieved, and the fabrication can be facilitated as a result of the simplification of the fabrication process. Moreover, in the process of forming contacts after the formation of transistors, current supplying capabilities can be set in addition to ROM data, and this contributes to a reduction in the lead time from the time when the ROM data are decided until the entire fabrication process is completed.
In accordance with yet another aspect of the invention, a read only memory is provided comprising: a plurality of switching elements provided so as to be connectable to and/or disconnectable from bit lines; wherein data to be read out are set by connecting and/or disconnecting the switching elements to/from the switching elements from the bit lines; and wherein, when reading out data, data corresponding to the presence or absence of switching elements connected to the bit lines are read out by discharging electric charge precharged in the bit lines with the switching elements selected by word lines; wherein the read only memory has a plurality of current supplying portions that constitute a current supplying circuit and are provided so as to be connectable to and/or disconnectable from the bit lines, the current supplying portions supplying electric current to the bit lines when the switching elements are selected by the word lines.
With this configuration, it is made possible to set the number of current supplying portions that are connected to a bit line in a data writing in read only memories in which data can be set (written) after the manufacture as well. Therefore, by appropriately compensating the off leakage current as described above, malfunctions and operation speed reductions are prevented.

Matsushita Electric Industrial Co., Ltd.


Among other disclosed subject matter, a method for managing supply and demand for a ware includes obtaining requirement information for a ware, the requirement information representing a forecasted demand for the ware at a specified time. The method includes generating supply information for the ware, generating pegging information, obtaining order information for the ware, modifying the requirement information and updating the pegging information. Any remainder of the forecasted demand of the requirement information that is not consumed by the order remains associated with the supply information in the pegging information.

Organizations use computer-based systems to controls some aspects of supplying wares. For example, a supply chain management system can be used to plan and/or execute the manufacture or procurement of goods that are to be sold to customers. Such systems can allow certain aspects of the process to be scheduled and specified, such as the amount of goods needed, when the delivery should take place, what machinery or other resources are to be used, to name a few examples.
Some systems have separate planning components. For example, some products from SAP AG include a Materials Requirement Planning component that can be used to plan the requirements for one or more materials, such as a raw material or a product. The output of a planning component can be based on forecasts of what future demands will be, and the plan can then be used to organize, analyze and/or execute operations in the organizations. For example, a plan can be laid out ahead in time, and more specific requirements such as sales orders can be added to the plan to replace parts thereof as they become available.


A method to design, implement and create distributed indexes for storing and comparing fingerprints of videos is presented. The method effectively utilizes cloud computing platforms that offer varying amounts of computing resources. The method enables the distributed index to scale to large numbers of data points and the distributed index is robust to failures within the computing resources maintaining the index. The method minimizes the memory required to maintain the distributed index and reduces the I/O operations needed to process operations performed on the index. The method improves the efficiency of the index to process queries.

Content-based video applications, such as copy detection and online video search, require the processing of large-scale and high dimensional data points. These data points represent many features extracted from videos. Given the substantial number of videos made available online and the increasing visual richness and complexities of online videos, processing such large amounts of data points has become a major challenge.
The present invention seeks to provide a mechanism for improving the handling and processing of large-scale and high dimensional data points within a video processing environment. In general terms the present invention relates to the processing of videos in a cloud computing environment.
Multidimensional trees for video processing are disclosed in C. Silpa-Anan and R. Hartley, Optimized KD Trees for Fast Image Descriptor Matching, In Proc. of IEEE Conference on Computer Vision and Pattern Recognition, pp. 1-8, Anchorage, Al., June 2008 and in J. Bentley, Multidimensional Binary Search Trees used for Associative Searching, Communications of the ACM, vol 18, No 9, pp. 509-517, 1975.
US2011/0064262 discloses attempts to protect 3D videos (videos consist of a base view and an enhancement view) by identifying regions in base and/or enhancement pictures that are not referenced by other pictures in the compressed 3D video. Then, these regions are watermarked and transmitted. Receivers of water-marked videos extract and verify the embedded watermarks.
US2008/0313140 discloses a method and apparatus for multi-dimensional content search and video identification which utilises multidimensional databases and indexes to search different structures such as videos. To do this, a compact hash of multidimensional vector signatures is used as the traversal index. For video search applications, global and local signatures around key points are used as discriminative information of the videos. To find matches, a likelihood score based on frame similarity is computed between the frames of a query video and original videos. Then, a correlation between the query video and original videos is generated by using a change in signatures of each sequence of frames in the query video and original videos.
US2008/0178302 discloses the use of video fingerprints to determine 2D video copies.
US2010/0318759 discloses a distributed backup storage which supports differential compression. It does not provide a distributed index for performing fast nearest neighbour searches.
The present invention provides a method of processing video fingerprint data in a cloud infrastructure, the method comprising the steps of analysing video data, extracting features from video data to form video fingerprint data, the video fingerprint data taking the form of multidimensional vectors, computing meta data and data points from the multidimensional vectors, inputting the multidimensional vector data into a distributed index having multiple levels, the distributed index comprising a directing tree and leaf nodes, storing meta data relating to the multidimensional vectors in the directing tree, storing data points computed from the multidimensional vectors in the leaf nodes, scaling the distributed index by increasing or decreasing the number of leaf nodes in the distributed index size dependent upon the number of multidimensional vectors to be stored, and distributing the leaf nodes across one or more client system.
Preferably, the multidimensional vectors are extracted from the leaf nodes and compared against multidimensional vectors extracted from another video stream.
Conveniently, all of the distributed index is hosted on a remote system.
Alternatively, only the leaf nodes are hosted on a remote system or systems.
Advantageously, the number of levels (L) to be included in the distributed index is determined by calculating the variance of the values to be stored in the distributed index.
Preferably, there are 2^L leaf nodes in the distributed index.
Conveniently, the method further includes the step of calculating the median value of the stored data points and using them as the split values at each level of the distributed index, dividing the data into two sub-sets.
Advantageously, the two sub-sets are a left sub-set and a right sub-set.
Conveniently, the median value process is repeated recursively.
Preferably, the method further includes the step of searching for the nearest neighbour of a data point.
Conveniently, the step of searching for a nearest neighbour of a data point includes traversing the directing tree.
Alternatively, the step of searching for a nearest neighbour of a data point includes the step of inserting the root of the directing tree into a priority queue.
Advantageously, the number of leaf nodes present in the distributed index is scaled by increasing the number of levels in the distributed index.
Preferably, when the number of levels is incremented by one, the number of leaf nodes available is doubled.
Conveniently, the method further includes the step of calculating the median value of the data points to be stored.
Advantageously, the method further includes the step of processing the multidimensional vectors with a map reduce algorithm.
The present invention also provides a system for processing video fingerprint data in a cloud infrastructure, system having a video fingerprint processor and a distributed index, wherein the video fingerprint processor is configured to extract features from video data to create multidimensional vectors, meta data and data points are computed from the multidimensional vectors, the distributed index has multiple levels and is formed of a directing tree and at least one leaf node, the directing tree is configured to store the meta data which relates to the multidimensional vectors, the or each leaf node is configured to store the data points computed from the multidimensional vectors, the distributed index is scalable and may be increased or decreased in size dependent upon the number of multidimensional vectors to be stored, and the or each leaf node is stored on a client system.
Preferably, the multidimensional vectors are extracted from the or each leaf node and are compared against multidimensional vectors extracted from another video stream, to detect similarities in the video streams.
Conveniently, all of the distributed index is hosted on a remote system.
Alternatively, the or each leaf node is hosted on a remote system.
Advantageously, the number of levels (L) to be included in the distributed index is determined by calculating the variance of the values to be stored in the distributed index.
Preferably, there are 2^L leaf nodes in the distributed index.
Conveniently, the distributed index is configured to calculate the median value of the stored data points and to use them as the split values at each level of the distributed index, to divide the data into two sub-sets.
Advantageously, the two sub-sets are a left sub-set and a right sub-set.
Preferably, the distributed index is configured to repeat the median value calculation recursively.
Conveniently, the distributed index is further configured to search for the nearest neighbour of a data point.
Advantageously, the search for the nearest neighbour of a data point includes traversal of the distributed index.
Alternatively, the search for the nearest neighbour of a data point includes inserting the root of the directing tree into a priority queue.
Preferably, the number of leaf nodes in the distributed index is scaled by increasing the number of levels in the distributed index.
Conveniently, when the number of levels is increased by one, the number of leaf nodes in the system is doubled.
Advantageously, when the number of levels in the distributed index is increased, the distributed index calculates the median value of the data points to be stored.
Preferably, the distributed index processes the multidimensional vectors with a map reduce algorithm.
Content-based video applications, such as copy detection and video search, require processing of large-scale and high dimensional data points. These data points represent many features extracted from videos. Given the substantial number of videos made available online and the increasing visual richness and complexities of online video content, the processing of such large volumes of data points presents a substantial challenge.
In an attempt to meet this challenge, embodiments of the invention present a distributed method to store and look up large-scale and high-dimensional data points extracted from online (and offline) video content.
In embodiments of the invention, features are extracted from videos and fingerprints (or signatures) are computed from these features. These fingerprints are stored in a distributed index, the fingerprints matched against known or catalogued videos or parts of videos. The index is distributed across computing resources in a cloud computing environment. The distributed index is then used to compare given query fingerprints against the fingerprints stored in the index for potential match.
Present technology may be employed to extract features from videos and compute fingerprints from videos or parts of videos. Such technology is conventional but innovative technologies can also be used to achieve a similar result. Examples of such methods are given in previous applications which disclose computing signatures from depth signals and from visual features of videos. However, it is to be understood that any method may be used to compute these fingerprints. The result of any fingerprint computation method is, in general, a set of multidimensional vectors. These multidimensional vectors are the input to the distributed index.
Embodiments of the present invention are concerned with creating, building and maintaining an index across a cloud computing environment.
From a high-level perspective, the distributed index according to the present invention takes two parts:                a directing tree, which contains no data points per se, but contains meta data computed from different dimensions of data points; and        leaf nodes, which contain actual data points, which are apportioned to respective leaf nodes in a predetermined manner so that each leaf node contains data points that are relatively close to the other data points in that leaf node as compared to the data points in other leaf nodes.
The directing tree may be used to find the leaf node that has the closest data points to a given query point. By construction (as detailed later), the directing tree may be balanced, which means that each branch has roughly the same number of nodes.
Leaf nodes may be mapped and stored in files in a distributed file system. Each node may be stored in a separate file. A file corresponding to a leaf node may be read in memory only if it needs to be either updated (i.e., inserting or deleting data points in them) or its items are the closest to a given query data point. Leaf nodes can be handled by different computing nodes in the cloud computing environment at the same time. The entire directing tree may be compact and may be maintained by a single server. The entire directing tree may be maintained in memory for fast processing. In contrast, the leaf nodes may be stored in the distributed file system.
Duplicated servers may be used to mitigate failures of the server maintaining the index as well as to process multiple query lookup operations in parallel. The number of levels in the directing tree, and hence the number of leaf nodes, may be used to control the scale of the data points stored in the index. Embodiments of the invention thus achieve scalability and robustness against failures.
The distributed index may be created from a set of data points. The index can be updated by adding new points or removing existing points. The index may be used to check whether given query points have similar ones in the index. The index may also perform distributed nearest neighbour searches to find the closest neighbours for each given query point.
The index may then return a result for each given query point of up to K nearest neighbours with a matching score for each neighbour. The query lookup process may be implemented in a distributed manner using the known MapReduce programming model which is discussed below. Operations to create and update the index are, in general, performed infrequently on a single server.
Embodiments of the invention use create and maintain a distributed implementation of an index using the MapReduce programming model disclosed in J. Dean and S. Ghemawat, MapReduce: Simplified Data Processing on Large Clusters, Communications of the ACM, vol 51, no 1, pp. 107-113, 2008. Embodiments of the invention do not improve the MapReduce model disclosed in Dean and Ghemawat, but do utilise the MapReduce model in their implementation.
MapReduce is a programming model designed for processing large volumes of data in parallel by dividing the work into a set of independent tasks. MapReduce programs are, in general, written in a particular style influenced by functional programming constructs, specifically idioms for processing lists of data.
MapReduce functionality is used in the implementation of embodiments of the present invention.
The first phase of a MapReduce program is mapping. A list of data elements are provided, one at a time, to a mapper function, which transforms each element individually to an output data element, as shown in FIG. 1.
The second phase of a MapReduce program is reducing, which allows values to be aggregated together. A reducer function receives an iterator of input values from an input list, and then combines these values together, returning output value results, as shown in FIG. 2.
MapReduce is particularly suitable for data intensive processing in which the input data can be too large for a single computer to process in a reasonable amount of time. Instead, the data is broken into chunks and processed by a plurality (potentially a large number) of different computers. The map function takes a key-value input and produces a key-value intermediate output. These data are stored on the local disk in a location which is tracked by a master node. The reduce function takes the intermediate values through remote file access and combines the results of matching keys. These results are written onto the DFS (Distributed File System). FIG. 3 demonstrates the key value processing steps and FIG. 4 shows the distributed job handling process between nodes.
The Apache Hadoop software library is a framework that allows for the distributed processing of large data sets across clusters of computers using the MapReduce programming model. It is designed to scale up from single servers to thousands of machines, each offering local computation and storage. Rather than relying on hardware to deliver high-availability, the library itself is designed to detect and handle failures at the application layer, so delivering a highly-available service on top of a cluster of computers, each of which may be prone to failures. The Hadoop software library also Includes Hadoop Distributed File System, or 'HDFS', is a distributed file system that provides high throughput access to application data. An example of a distributed file system is shown in FIG. 5.
In the present invention, Hadoop may be used as an implementation and framework for the development and deployment of the MapReduce functionality.
Amazon Web Services (or 'AWS') is a collection of remote computing services that together make up a cloud computing platform, offered over the Internet by Amazon. Three services offered by AWS are:                Amazon Simple Storage Service ('S3'), which provides scalable online storage;        Amazon Elastic Cloud Compute ('EC2'), which provides scalable online virtual computing power; and        Amazon Elastic Map Reduce ('EMR'), which provides a hosted Hadoop framework running on Amazon EC2 and S3 services.
The steps undertaken in creating and updating the index, along with the distributed look up operations are discussed below.
As mentioned previously, the distributed index may be composed of a directing tree and leaf nodes. The directing tree may be based on a modified version of K-dimensional (KD) trees. Embodiments of the invention, comprising a distributed index mechanism, improve on the prior art trees, with the improvements including storing data points in the leaf nodes and dynamically using a subset of the dimensions of the data points. The index embodying the present invention may be distributed and may run on clusters with variable numbers of machines.
A KD-tree is a binary tree in which every node is a K-dimensional point. Every non-leaf node may be considered as implicitly generating a splitting hyper-plane that divides the space into two parts, known as subspaces. Points to the left of this hyper-plane represent the left sub-tree of that node and points right of the hyper-plane are represented by the right sub-tree. The hyper-plane direction is chosen such that every node in the tree is associated with one of the k-dimensions, with the hyper-plane perpendicular to the axis of the k-dimension.
The present invention modifies traditional KD trees to design a distributed index. This is achieved by data points not being stored in non-leaf nodes, which achieves substantial memory saving. All data points are stored in leaf nodes. Further, map leaf nodes files are mapped and stored on a distributed file system, which enables distributed processing of look-up queries.
Additionally, only a subset of the dimensions of the data points is used, as opposed to all dimensions. This is because traditional KD tree structures perform poorly for high dimensional data sets. Video processing applications are required to process high dimensional data sets. Also, the index is increased and decreased in size dynamically, based on the number of data points. This is achieved by controlling the number of dimensions used in the index. This dynamic feature allows us efficiently support video processing applications with different scales.
Embodiments of the present invention include a distributed implementation of the index using the MapReduce programming model disclosed in Dean and Ghemawat which achieves scalability and robustness against failures.
To increase the efficiency and accuracy of the index, a subset of the dimensions are used to construct the index. The number of dimensions in each data point is denoted as D. Then, M≤D is taken as the dimensions used in the tree.
To select M, if the data set is large, a random representative sample of it may be taken. Otherwise, the whole data set may be used. Then, for each dimension of the data points, the variance of its values may be calculated.
Once the variance is calculated, the dimensions may be ranked in descending order based on their variances, and the first M dimensions may be taken which have the highest variances.
It is to be understood that several other methods may be used to select dimensions. For example, statistical parameters other than the variance can be used. Also, principal component analysis ('PCA') can be used to identify important components of the data set and employ these important components in building the index.
L may be used to denote the number of levels in the tree. Whilst M is fixed, L may change as the number of data points changes. L is also used to control the size of the index, as L controls the number of levels in the index. If L becomes larger than the number of chosen dimensions M, some dimensions may be repeated multiple times to reach the number of desired tree levels.
After choosing the number of levels (L), the index may be created. Firstly, the maximum depth (number of levels) of the index is set to L. Thus, the tree may have 2L (2^L) leaf nodes. Then, at each level of the index (starting from the top level), the data points may be sorted with respect to the dimension corresponding to that level.
Next, the median values of the sorted data points are used as the split values at each level and are stored in the interior nodes of the index. Subsequently, the data set is divided to left and right sub-sets based on the split values, and the left sub-set is inserted on the left sub-tree, and the right sub-set on the right sub-tree. This procedure may then be recursively repeated until the leaf node is reached, with the actual data points stored in leaf nodes. FIG. 6 shows an overview of the job handling according to the present invention.
An example of high level code for an index construction process is given below.
 points [ ]constructIndex (curIndexNode, start, end, curDimInd){ if (curDimInd is the last dimension)  set curIndexNode to be a leaf node else{sort (points, start, end )  median = ( start + end ) / 2  curIndexNode->splitValue = points[median] [curDimInd]  constructIndex (curIndexNode->left, start, median,   curDimInd+1)  constructIndex (curIndexNode->right, median+1, end,   curDimInd+1)}}
When a query data point is given, the nearest neighbours for the point may then be found. To achieve this, the directing tree is traversed until the leaf node is reached, containing data points. Then, the closest neighbours to the given point in the file corresponding to the found leaf node may be found. This finding neighbour operation may be carried out in parallel for many points at the same time. The details of the distributed version are set out in a later section of this document.
An example of high-level code for a find neighbour operation is given below.
getLeafNodeID (KDtreeNode, features){ if (KDtreeNode is leaf node)  return KDtreeNode -> fileID else if (features[currentDimension] <= KDtreeNode ->splitValue)  return getLeafNodeID (KDtreeNode -> left, features); else  return getLeafNodeID (KDtreeNode -> right, features);}
An alternative method to find neighbours is given below. This method may find more and closer neighbours by searching in multiple leaf nodes or 'bins'. The multiple bins may be chosen such that they contain the potential nearest neighbours. This method may require more processing power, but, in general, yields better neighbours, and may search candidate bins in ascending order of their distances to a given query point. It may maintain a priority queue of nodes, where the priority of a node is inversely proportional to its distance to the query point and the rectangle corresponding to this node.
The steps of this neighbor find method may include inserting the root of the KD tree into a priority queue, and then repeating the following steps:                Get the top node from the queue with the highest priority;        If it is a leaf node, or 'bin', add it to a list of preferred bins;        If not, calculate the distance from the query point to its child nodes, and insert them into the priority queue; and        Terminate the algorithm if the maximum number of bins is reached or the priority queue is empty.
An example of high-level code for this find neighbour method is shown below.
 List ResultBins = [ ]PriorityQueue qTreeNode currentNodeAdd tree root to qWHILE q is not emptycurrentNode = top of q WHILE currentNode is not Leaf  Calculate the distance from the query  point to the splitting dimension of the currentNode  IF distance < 0 //closer to left node   add the right child of currentNode to q   currentNode = the left child of currentNode  ELSE IF distance > 0 //closer to right node   add left child of currentNode to q   currentNode = right child of currentNode add binID of currentNode to resultBins IF count of resultBins = Max number Of Bins  terminate the algorithm
Insert and delete operations work as in regular binary trees. An example of code for an insert operation is given below. (The initial call is addVector (root, newVector), and it is assumed that the dimensions are indexed 0, 1, . . . , DIM−1, The variable 'currentDimension' keeps track of the current cutting dimension.
 InsertDataPoint (IndexNode, Point){ if (IndexNode is leaf){  Add Point to existing points in IndexNode} else if (dimensions[currentDimension] <= IndexNode ->splitValue)  InsertDataPoint (IndexNode ->left, Point) else  InsertDataPoint (IndexNode ->right, Point)}
To delete a data point, the bin for the data point may be found using the find algorithm above. Then, the point in the file corresponding to the found bin located, the point deleted and the deleted point replaced by the last point in the file.
When the number of data points increases/decreases significantly, the index internal structured needs to be scaled up or down to handle the significant change of the data size. We design our index to be highly scalable and can adapt to the dynamic changes in number of data points. We achieve this dynamic scalability by controlling the number of levels in the index, which is determined by the number of dimensions M used from the data points. Specifically, increasing M by one, doubles the number of nodes, and vice versa.
The index may be scaled up as follows (with similar operations used to scale it down). Firstly, the new dimension to be added must be selected. This may, in general, be the dimension which has the highest variance and not included in the tree already. Then, the contents of each file associated with the leaf nodes of the index may be sorted, based upon the value of the new dimension.
Subsequently, the median value for the sorted data points may be calculated, and then each leaf node may be split into two branches, with their associated files split in two, adding a new level to the index.
When more data points are provided, the tree bins sizes increase and the files associated to them become larger resulting in a low performance search. In order to avoid such a case, the KD-tree must be scaled up.
The MapReduce model divides the input data into splits, in which the data is organized as key-value pairs. Then, it creates a number of mapper functions to process each key-value pair in the input splits. Multiple mappers can run concurrently on each node in the cluster. Ideally, a mapper is run on the same node where the input split resides. After all mappers finish, reducer functions are executed to process the outcome of the mappers. Each reducer handles a fraction of the output key space, and produces the final results. Multiple stages of mapper and reducers can be chained together.
The aim of the present invention is to provide efficient and reliable processing of large-scale data sets. The most frequently invoked function on the distributed index is finding nearest neighbours for given query points. This is the function that the index is optimised to perform. Other functions, such as construction and updating the index, are, in general, undertaken infrequently over long periods. Thus, they are considered more offline functions and can be performed on duplicated copies of the index on backup machines. Once these infrequent functions are performed, the new index is copied over to the main index servers.
The MapReduce function is divided into two main map reducing stages. The first stage is provided with a set of query points and the function calculates the K nearest neighbours for each query point. The second stage depends on the specific application that uses the distributed index. For example, in the video copy detection application, the second stage constructs similarity matrices between query videos and reference videos to find potentially copied videos.
High-level code for the first map-reduce stage of our design is set out below, which consists of one Mapping task followed by two Reducing tasks. The second stage depends on the specific application using the index.
Map (Key, Value){ // Input: file with query points // Output: Nearest Bins IDs for each query point // Task: find leaf nodes that have neighbors of query // points, emit pairs of <LeafNodeID, query point> For each query point q {   Query the tree get nearest bins for q   Foreach (bin in the nearest bins)   {     Emit(binId, query vector)   } }}/*** First Reducer ***/Reduce (Key, Value){ // Input: key is a LeafNodeID, and Value is the list of // query points having neighbors in file corresponding // to LeafNodeID // Output: pairs of <q, list of k neighbors> for each // query point from that specific leaf node // Task: calculate the nearest neighbors for each query // point Load the bucket from the disk Initialize map from BucketID to corresponding query  vectors Initialize neighbor list to fill the nearest m frame  matches to the query vectors Foreach (Query Vector in Query Vectors List) {   Foreach (Reference vector in the bucket)    {     Initialize refVectorID     Initialize qVectorID     Calculate the distance between current query      vector the current reference vector     If (distance is larger than current threshold)      {       Initialize framematch instance (fm) with        current refVectorID,qVectorID,distance       neighbors.add(fm)      }     } Sort neighbors with respect to distance Pick the nearest m frame matches Foreach nearest frame match f  {   Emit (qVideoID, f) }}/*** Second Reducer ***/Reduce (Key, Value){ // Input: key is a LeafNodeID, and Value is the list of // query points identified as having neighbors in file // corresponding to LeafNodeID // Output: pairs of <q, list of k neighbors> for each // query point from all bins // Task: Get the nearest K matches for each query video // against all the nearest bins, and sort them. Sort the input framematch list on the distance // now we have all frame matches from all nearest bins Pick the nearest m framematches. Foreach nearest frame match f {  Emit ([refVideoID,qVideoID], f) }}
A novel method to design, implement and create distributed indexes for storing and comparing fingerprints of videos is presented. The method effectively utilises cloud computing platforms that offer varying amounts of computing resources. The method enables the distributed index to scale to large numbers of data points and the distributed index is robust to failures within the computing resources maintaining the index. The method minimizes the memory required to maintain the distributed index and reduces the I/O operations needed to process operations performed on the index. The method improves the efficiency of the index to process queries.
When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.
The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

System and method to store video fingerprints on distributed nodes in cloud systems


A system and method are presented for interfacing multiple plain old telephone system (POTS) devices with multiple cellular devices in communication with a cellular network to enable efficient communication among these devices. In a broad sense, the system includes an interface configured to function as a bridge between the POTS devices and the cellular devices. The interface selectively routes call attempts from a POTS device to one of a group of cellular devices which connect the calls from the POTS device over the cellular network. The interface may be configured to detect a key sequence for selecting a particular cellular device in the group during an outgoing call attempt from the POTS device. The interface then routes the outgoing call to the selected cellular device. The interface may also be configured to detect a telephone number entered into the POTS device during an outgoing call attempt and route the outgoing call to a particular cellular device based on criteria pre-programmed in the interface. The interface may also be configured to generate distinctive signaling, such as ring tones, for the POTS devices to distinguish incoming calls to the group of cellular devices.

The telephone has greatly facilitated communications between parties, especially when great distances separate the parties. Metropolitan cities and suburbs typically have sufficient access to a public switched telecommunications/telephone network (PSTN), as well as cellular networks. As access to PSTN and cellular networks has increased, a single subscriber may have several telephony devices, including plain old telephone system (POTS) devices and cellular telephones, available for use. As a result of having multiple telephony devices in the home, solutions have been developed involving cellular phone docking stations which enable the use of POTS devices over a cellular network. These solutions, however, fail to account for matching multiple cellular phone lines with multiple POTS lines including the ability to select a cellular phone line for use with one or more selected POTS devices as well as the ability to provide distinctive signaling for POTS devices receiving calls from one of several cellular phone lines.

This patent is subject to a terminal disclaimer.

System and method for interfacing plain old telephone system (POTS) devices with cellular devices in communication with a cellular network


A bone density meter including a light emission unit which emits light toward a surface of a user's body. A light reception unit receives the light emitted from the light emission unit toward the body surface and propagated in a portion of the body that includes bone. A bone density computation unit determines the bone density based on the amount of light received by the light reception unit. The light emission unit emits light toward the body surface at a portion having a thin subcutis, and the light reception unit receives the light propagated in the body through the portion at which the subcutis is thin.

The present invention relates to a bone density meter that uses light to measure bone density.
Methods for measuring the bone density of a measurement subject, such as a person, using light are known in the prior art. Japanese Laid-Open Patent Publication No. 2008-155011 describes one example of a bone density meter. The bone density meter includes a light emission unit, a light reception unit, a variation tendency calculation means, and a density calculation means. The light emission unit emits light into the measurement subject as it varies the light intensity. The light reception unit receives the reflection of the emitted light from the measurement subject. The variation tendency calculation means calculates a variation tendency from the intensity of the reflection light. The density calculation means calculates the bone density of the measurement subject from the variation tendency. In this manner, the bone density meter of the prior art varies the intensity of the light emitted from the light emission unit to evaluate and measure the bone density from the variation in the intensity of the reflection light.
In the bone density meter of the prior art, when measuring the bone density, for example, at a portion at which the subcutis is thick, light may not reach the bone due to factors such as insufficient output of the light emission unit. In such a case, accurate detection of the bone density is difficult.


A hydrocracking catalyst comprising zeolite crystallized as a layer on the surface of a porous alumina-containing matrix, said zeolite-layered matrix arranged in a configuration to provide macropores in which the zeolite layer is provided on the walls of the macropores. Hydrogenating metals can be incorporated into the catalyst.

Hydrocracking is a versatile petroleum refining process which enjoys widespread use in the refining industry. Hydrocracking has the ability to process a wide range of difficult feedstocks into a variety of desirable products. Feedstocks which may be treated by this process include heavy naphthas, kerosenes, refractory catalytically cracked cycle stocks and high boiling virgin and coker gas oils. At high severities, hydrocracking can convert these materials to gasoline and lower boiling paraffins; lesser severities permit the higher boiling feedstocks to be converted into lighter distillates such as diesel fuels and aviation kerosenes.
Hydrocracking is conventionally carried out at moderate temperatures of 350° C. to 450° C. (650° F. to 850° F.) and at high pressures, over 7,000 kPa (1,000 psig) because the thermodynamics of the hydrocracking process become unfavorable at higher temperatures. In addition, high hydrogen pressures, usually at least 800 psig are usually required to prevent catalyst aging and so to maintain sufficient activity to enable the process to be operated with a fixed bed of catalyst for periods of one to two years without the need for regeneration.
Environmental concerns, especially with sulfur oxides and nitrogen oxides emissions, have led petroleum refiners to depend more heavily than in the past on hydrodesulfurization and hydrocracking processes. Availability of by-product hydrogen from naphtha reforming no doubt has also cooperated to foster this dependence. Other factors too, have come into play to make hydroprocessing of increasing importance. Among these factors is that high quality crude oils for lube and fuels refineries are expected to progressively become more scarce. Also, refineries that include a fluid catalytic cracking (FCC) plant generate large volumes of dealkylated, aromatic refractory effluents, commonly known as FCC Cycle Oils. Decrease in demand for the fuel oil products into which these FCC Cycle Oils were previously incorporated has added to the practice of working them off by incorporation with a hydrocracker feedstock. The hydrocracking process, unlike catalytic cracking, is able to effectively upgrade these otherwise refractory materials.
Hydrocracking is an established petroleum refining process. The hydrocracking feedstock is invariably hydrotreated before being passed to the hydrocracker in order to remove sulfur and nitrogen compounds as well as metals and, in addition, to saturate olefins and to effect a partial saturation of aromatics. The sulfur, nitrogen and oxygen compounds may be removed as inorganic sulfur, nitrogen and water prior to hydrocracking although interstage separation may be omitted, as in the Unicracking-JHC process. Although the presence of large quantities of ammonia may result in a suppression of cracking activity in the subsequent hydrocracking step, this may be offset by an increase in the severity of the hydrocracking operation.
In the hydrotreater, a number of different hydrogenation reactions take place including olefin and aromatic ring saturation but the severity of the operation is limited so as to minimize cracking. The hydrotreated feed is then passed to the hydrocracker in which various cracking and hydrogenation reactions occur.
In the hydrocracker, the cracking reactions provide olefins for hydrogenation while hydrogenation in turn provides heat for cracking since the hydrogenation reactions are exothermic while the cracking reactions are endothermic; the reaction generally proceeds with generation of excessive heat because the amount of heat released by the exothermic hydrogenation reactions usually is much greater than the amount of heat consumed by the endothermic cracking reactions. This surplus of heat causes the reactor temperature to increase and accelerate the reaction rate, but control is provided by the use of hydrogen quench.
Conventional hydrocracking catalysts combine an acidic function and a hydrogenation function. The acidic function in the catalyst is provided by a porous solid carrier such as alumina, silica-alumina, or by a composite of a crystalline zeolite such as faujasite, Zeolite X, Zeolite Y or mordenite with an amorphous carrier such as silica-alumina. The use of a porous solid with a relatively large pore size in excess of 7 A is generally required because the bulky, polycyclic aromatic compounds which constitute a large portion of the typical feedstock require pore sizes of this magnitude in order to gain access to the internal pore structure of the catalyst where the bulk of the cracking reactions take place.
The hydrogenation function in the hydrocracking catalyst is provided by a transition metal or combination of metals. Noble metals of Group VIIIA of the Periodic Table, especially platinum or palladium may be used, but generally, base metals of Groups IVA, VIA and VIIIA are preferred because of their lower cost and relatively greater resistance to the effects of poisoning by contaminants. The preferred base metals for use as hydrogenation components are chromium, molybdenum, tungsten, cobalt and nickel; and, combinations of metals such as nickel-molybdenum, cobalt-molybdenum, cobalt-nickel, nickel-tungsten, cobalt-nickel-molybdenum and nickel-tungsten-titanium have been shown to be very effective and useful.
The porous support which provides the acidic functionality in the catalyst may comprise either an amorphous or a crystalline material or both. Amorphous materials have significant advantages for processing very high boiling feeds which contain significant quantities of bulky polycyclic materials (aromatics as well as polynaphthenes) since the amorphous materials usually possesses pores extending over a wide range of sizes and the larger pores, frequently in the size range of 100 to 400 Angstroms are large enough to provide entry of the bulky components of the feed into the interior structure of the material where the acid-catalyzed reactions may take place. Typical amorphous materials of this kind include alumina and silica-alumina and mixtures of the two, possibly modified with other inorganic oxides such as silica, magnesia or titania.
Crystalline materials, especially the large pore size zeolites such as zeolites X and Y, have been found to be useful for a number of hydrocracking applications since they have the advantage, as compared to the amorphous materials, of possessing a greater degree of activity, which enables the hydrocracking to be carried out at lower temperatures at which the accompanying hydrogenation reactions are thermodynamically favored. In addition, the crystalline catalysts tend to be more stable in operation than the amorphous materials such as alumina. The crystalline materials may, however, not be suitable for all applications since even the largest pore sizes in these materials, typically about 7.4 Angstroms in the X and Y zeolites, are too small to permit access by various bulky species in the feed. For this reason, hydrocracking of residuals fractions and high boiling feeds has generally required an amorphous catalyst of rather lower activity.
The crystalline hydrocracking catalysts generally tend to produce significant quantities of gasoline boiling range materials (approximately 330° F.−, 165° C.−) materials as product. Since hydrocracked gasolines tend to be of relatively low octane and require further treatment as by reforming before the product can be blended into the refinery gasoline pool, hydrocracking is usually not an attractive route for the production of gasoline. On the other hand, it is favorable to the production of distillate fractions, especially jet fuels, heating oils and diesel fuels since the hydrocracking process reduces the heteroatom impurities characteristically present in these fractions to the low level desirable for these products.
In fuels hydrocracking, the zeolite content of the catalyst is conventionally as high as possible for the desired acidity; conversely the amount of matrix which supports the metal component is limited and as the proportion of zeolite in the catalyst increases, the amount of support available for the metal component decreases with the result that the hydrogenation activity becomes limited at the high zeolite loadings requisite to fuels hydrocracking.

Hydrocracking catalyst and process using insitu produced Y-fauajasite


A multimode optical fiber having a first laser bandwidth greater than 220 MHz.km in the 850 nm window, a second laser bandwidth greater than 500 MHz.km in the 1300 nm window, a first OFL bandwidth of at least 160 MHz.km in the 850 nm window, and a second OFL bandwidth of at least 500 MHz.km in the 1300 nm window is disclosed. The multimode fiber is capable of operating in telecommunication systems employing both LED power sources and high power laser sources. Methods of making and testing the multimode optical fiber are also disclosed.

1. Field of the Invention
The present invention relates generally to a multimode optical fiber and method for use with telecommunication systems employing low data rates, as well as systems employing high data rates, and more particularly, to a multimode optical fiber and method optimized for applications designed for state of the art laser sources, as well as common light emitting diode sources.
While the present invention is subject to a wide range of applications, it is particularly well suited for use in telecommunications systems designed to transmit data at rates equal to and exceeding one gigabit/sec.
2. Technical Background
The goal of the telecommunication industry is generally to transmit greater amounts of information, over longer distances, in shorter periods of time. Over time, it has been shown that this objective is a moving target with no apparent end in sight. As the number of systems users and frequency of system use increase, demand for system resources increases as well.
Until recently, data networks have typically been served by Local Area Networks (LANs) that employ relatively low date rates. For this reason, Light Emitting Diodes (LEDs) have and continue to be the most common light source in these applications. However, as data rates begin to increase beyond the modulation capability of LEDs, system protocols are migrating away from LEDs, and instead, to laser sources. This migration is evidenced by the recent shift toward systems capable of delivering information at rates equal to and exceeding one (1) gigabit/sec.
While such transmission rates will greatly enhance the capabilities of LANs, it does create an immediate concern for system owners. Multimode optical fiber currently employed in telecommunication systems is designed primarily for use with LED sources and is generally not optimized for use with the lasers envisioned to operate in systems designed to transmit information at rates equal to or greater than one (1) gigabit/sec. Laser sources place different demands on multimode fiber quality and design, compared to LED sources.
Historically, the index profile at the core of multimode fibers has been tuned to produce high bandwidth with LED sources, which tend to overfill the core. The combination of the light intensity distribution from the LED source input pulse and the index profile of the fiber produces an overfilled modal weighting that results in an output pulse that has a relatively smooth rise and fall. Although peaks or plateaus resulting from small deviations from the ideal near-parabolic index profile do occur, their magnitude does not impact system performance at low data rates. In laser based systems, however, the intensity distribution of the source concentrates its power near the center of the multimode fiber. Consequently, small deviations in the fiber profile can produce significant perturbations in the impulse rise and fall, which can have a large effect on system performance. This effect can manifest itself in the form of excessively low bandwidth, as excessively high temporal jitter, or both. Although it is possible to correct these deficiencies to some degree by changing the launch condition of the source, such as the offset launch mode conditioning patch cord or the laser beam expander, this is typically not a practical solution for system owners.
A typical campus layout for a LAN system is designed to meet certain specified link lengths. The standard for the campus backbone (which travels between buildings) typically has a link length of up to about 2 km. The building backbone or riser (which travels between floors of a building) typically has a link length of up to about 500 meters. The horizontal link length (which travels between offices on a floor of a building) typically has a link length of up to about 100 meters. Older and current LAN technology, such as 10 Megabit Ethernet, can achieve a 2 km link length transmission with standard grade multimode optical fiber. However, next generation systems capable of gigabit/sec. and higher transmission rates cannot achieve all of these link lengths with standard multimode fiber presently available. In the 850 nm window, standard multimode fiber is limited to a link length of approximately 220 meters. In the 1300 nm window, standard grade fiber is limited to a link length of only about 550 meters. Accordingly, present technology only enables, at most, coverage for about two of the three campus link lengths. To fully enable a LAN for gigabit/sec. transmission rates, a multimode fiber capable of transmitting information over each of the three link lengths is necessary.
As used herein, overfilled (OFL) bandwidth is defined as the bandwidth using the standard measurement technique described in EIA/TIA 455-51 FOTP-51A, xe2x80x9cPulse Distortion Measurement of Multimode Glass Optical Fiber Information Transmission Capacityxe2x80x9d, with launch conditions defined by EIA/TIA 455-54A FOTP-54 xe2x80x9cMode Scrambler Requirements for Overfilled Launching Conditions to Multimode Fibersxe2x80x9d.
As used herein, laser bandwidth is defined as and measured using the standard measurement technique described in EIA/TIA 455-51 and either of the following two launch conditions methods. Method (a) is used to determine the 3 dB bandwidth at 1300, and method (b) is used to determine the 3 dB bandwidth at 850 nm. Method (a), which is used to determine the 3 dB laser bandwidth at 1300 nm, utilizes a 4 nm RMS spectral width 1300 nm laser with a category 5 coupled power ratio launch modified by connection of a 2 meter, standard step index, single-mode fiber, patch-cord wrapped twice around a 50 mm diameter mandrel. The launch condition is further modified by mechanically offsetting the central axis of the singlemode fiber from that of the multimode fiber in such a manner that a 4 um lateral offset between the central axis of the core of the single mode fiber patch-cord and the multimode fiber under test is created. Note: category 5 coupled power ratio is described in and measured using procedures in TIA/EIA 526-14A OFSTP 14 appendix A xe2x80x9cOptical Power Loss Measurements of Installed Multimode Fiber Cable Plant. Method (b), which is used to determine the 3 dB laser bandwidth at 850 nm, utilizes a 0.85 nm RMS spectral width 850 nm OFL launch condition, as described in EIA/TIA 455-54A FOTP 54, connected to a 1 meter length of a specially designed multimode fiber having a 0.208 numerical aperture and a graded index profile with and alpha of 2. Such a fiber can be created by drawing down a standard 50 xcexcm diameter core multimode fiber having a 1.3 index of refraction delta (delta=no2xe2x88x92nc2/2nonc=where no=the index of refraction of the core and nc=the index of refraction of the cladding) to a 23.5 xcexcm diameter core.
Today, in order to increase distance, manufacturers typically shift bandwidth between two wavelength windows by changing the shape of the refractive index profile. Depending upon the changes made, the result is either high OFL bandwidth at the 850 nm window with low OFL bandwidth at the 1300 nm window, or low OFL bandwidth at the 850 nm with high OFL bandwidth at the 1300 nm window. For example, for a standard 2% Delta 62.5 um FDDI-type fiber, the refractive index profile can be adjusted to result in OFL bandwidth of 1000 MHz.km at 850 nm and 300 MHz.km at 1300 nm, or it can be adjusted to result in OFL bandwidth of 25 MHz.km at 850 nm and 400 MHz.km at 1300 nm. With such multimode optical waveguide fibers having standard xe2x80x9calphaxe2x80x9d profiles, however, it is not possible to achieve an OFL bandwidth of 1000 MHz.km at 850 nm and 4000 MHz.km at 1300 nm. More typically, manufacturing tolerances would allow 850 nm/1300 nm OFL bandwidths of 600 MHz.km/300 MHz.km or 200 MHz.km/1000 MHz.km but not 600 MHz.km/1000 MHz.km.
There is a disconnect, however, between these historical bandwidth shifts, and what is necessary for gigabit/sec. transmission rates. Because high speed lasers are the standard light source for LANs designed to deliver information at rates exceeding a gigabit/sec., a multimode optical fiber having increased bandwidth at both the 850 nm and 1300 nm window is desired.
Moreover, because such LANs are in their infancy, all of the system components necessary to meet and/or exceed transmission rates of one gigabit/sec. are not yet fully reduced or practiced, optimized, and/or tested. For these reasons, it is not practical to replace existing LAN systems with a new LAN system speculatively designed to meet or exceed such high data rates. While it may be possible to achieve this result, it will likely not be the preferred or optimal solution, as following such a course of action will likely result in costly upgrades to the system and potentially a rework of the entire system.
The present invention is directed to a multimode optical fiber that is optimized for high speed laser sources capable of 1.0, 2.5, and 10 gigabit per second data transmission while exceeding the link length requirements discussed above. Moreover, the same multimode optical fiber maintains sufficiently high OFL bandwidth to support the transmission of information with the 1300 nm and 850 nm LED sources presently used in LAN systems. Such a multimode optical fiber will enable current LAN system owners to maintain their present LED based LAN systems, while at the same time enable them to easily transfer to a xe2x80x9cGigabit Ethernet Systemxe2x80x9d without having to undertake a costly multimode fiber upgrade. As used herein, xe2x80x9cGigabit Ethernet Systemxe2x80x9d is defined as a telecommunication system, such as a LAN, which is capable of transmitting data at rates equal to and/or exceeding one (1) gigabit/sec.
Accordingly, one aspect of the present invention relates a multimode fiber having a first laser bandwidth greater than 220 MHz.km in the 850 nm window, a second laser bandwidth greater than 500 MHz.km in the 1300 nm window, a first OFL bandwidth of at least 160 MHz.km in the 850 nm window, and a second OFL bandwidth of at least 500 MHz.km in the 1300 nm window. Such a multimode optical fiber has a variety of uses in the telecommunication industry, and is particularly well suited for use in telecommunication systems employing high speed laser sources. Such a fiber has the added benefit of providing sufficient OFL bandwidth for LED sources presently used in LAN systems.
In another aspect, the invention is directed to a multimode transmission system capable of transmitting data at rates equal to and exceeding one gigabit/sec. The multimode transmission system includes a laser source which transmits at least one gigabit/second of information, and a multimode optical fiber communicating with the laser source. The multimode optical fiber has a first laser bandwidth of at least 385 MHz.km in the 850 nm window which is capable of carrying the information at least 500 meters. The multimode optical fiber also has a second laser bandwidth of at least 746 MHz.km in the 1300 nm window for carrying the information at least 1000 meters. In addition, the multimode optical fiber includes first and second OFL bandwidths sufficiently high to be used with 850 nm and 1300 nm LED sources.
Another aspect of the present invention relates to a multimode optical fiber having a 62.5 xcexcm core, and a cladding bounding the core. The cladding has a refractive index lower than the refractive index of the core, and the multimode optical fiber exhibits a DMD profile, which when measured at a wavelength of 1300 nm, includes a first region having an average slope measured from (r/a)2=0.0 to 0.25, and a second slope region having an average slope measured from (r/a)2=0.25 to 0.50. The slope of the first region is preferably greater than the slope of the second region. More preferably, the slope of the first region is greater than 1.5 times the slope of the second region.
In a further aspect, the present invention is directed to a method of forming a multimode optical fiber. The method includes the steps of thermochemically reacting a silica containing precursor reactant and at least one dopant reactant to form soot, and delivering the soot to a target in a manner sufficient to produce a glass preform having specified characteristics. The glass preform is drawn into a multimode optical fiber having a 62.5 xcexcm core region and a cladding region bounding the core region. The reacting step includes selecting a precursor reactant and a dopant reactant according to a soot deposition recipe sufficient to result in a multimode optical fiber which exhibits a DMD profile, which when measured at a wavelength of 1300 nm, has a first average slope measured over a first region from (r/a)2=0.0 to 0.25, and a second average slope measured over a second region from (r/a)2 0.25 to 0.50, the first average slope being greater than the second average slope.
The multimode optical fiber of the present invention results in a number of advantages over other multimode optical fibers known in the art. One such advantage is that the multimode optical fiber of the present invention is fully compatible for use with high speed laser sources, as well as LED sources. Accordingly, the multimode optical fiber of the present invention can be used with conventional local area networks employing LED sources, and can be used with Gigabit Ethernet Systems, which employ high speed laser sources.
In addition, the multimode optical fiber of the present invention eliminates the need for costly mode conditioning patch cords often used to enable operation in the 1300 nm operating window for Gigabit Ethernet System protocol. For many multimode optical fibers, a mode conditioning patch cord is used to move power away from the center of the multimode fiber in order to avoid center line profile defects which typically result from some manufacturing processes. Because the preferred multimode optical fiber of the present invention is manufactured using the Outside Vapor Deposition process (OVD), the preferred multimode optical fiber of the present invention has reduced centerline profile defects. Accordingly, a mode conditioning patch cord is no longer needed to enable operation in the 1300 nm operating window of the preferred fiber of the present invention, thus allowing for on-center launch or slightly off-set due to loose connector tolerances, resulting in ease of installation and use.
Moreover, the multimode optical fiber of the present invention optimizes laser performance with a variety of laser sources, such as, but not limited to, 780 nm Fabry-Perot lasers, 850 nm Vertical Cavity Surface Emitting Lasers (VCSELs), 1300 nm Fabry-Perot lasers, and low cost 1300 nm transmitters envisioned for the future. The multimode optical fiber of the present invention is also designed to support operation at 2.5 and 10 gigabits/second over significant link lengths when used with high performance lasers in more advanced telecommunication systems.
Additional features and advantages of the invention will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the invention as described herein, including the detailed description which follows, the claims, as well as the appended drawings.
It is to be understood that both the foregoing general description and the following detailed description are merely exemplary of the invention, and are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate various embodiments of the invention, and together with the description serve to explain the principles and operation of the invention.

Laser optimized multimode fiber and method for use with laser and LED sources and system employing same


An input receiver includes a first input receiving unit, a second input receiving unit, a delay unit, and a first logic unit. The first input receiving unit receives an inverse wake-up signal, an external clock enable signal, a first voltage, and a reference signal, and then generates a first enable signal according to the external clock enable signal and the reference signal. The second input receiving unit receives the external clock enable signal, the first voltage, and an inverse enable voltage, and then generates a second enable signal as its output according to the external clock enable signal. The delay unit generates a wake-up signal according to the second enable signal. The first logic unit receives the wake-up signal and the first enable signal, and then generates an internal clock enable signal according to the wake-up signal and the first enable signal.

1. Field of the Invention
The present invention relates an input receiver and an operation method thereof, and particularly to an input receiver and an operation method thereof that can have lower power consumption when the input receiver enters a power down mode, and have a good setup time, a good hold time, a shorter response time, and better noise immunity when the input receiver enters or leaves the power down mode.
2. Description of the Prior Art
Please refer to FIG. 1. FIG. 1 is a diagram illustrating an input receiving circuit 102 for receiving an external clock enable signal XCKE and an enable register 104 according to the prior art. As shown in FIG. 1, when the external clock enable signal XCKE is changed from high to low, an internal clock enable signal ICKE outputted by the input receiving circuit 102 can be also immediately changed from high to low, and the enable register 104 can keep a latch clock enable signal LCKE outputted thereof low according to an inner clock ICLK, resulting in a system buffer (e.g. a clock buffer, an address buffer, a command buffer, or a data buffer of a dynamic random access memory) receiving the latch clock enable signal LCKE being turned off. That is to say, the system enters a power down mode.
In addition, when the external clock enable signal is changed from low to high, the internal clock enable signal ICKE outputted by the input receiving circuit 102 can be also immediately changed from low to high, and the enable register 104 can keep the latch clock enable signal LCKE outputted thereof high according to the inner clock ICLK, resulting in the system buffer (e.g. the clock buffer, the address buffer, the command buffer, or the data buffer of a dynamic random access memory) receiving the latch clock enable signal LCKE being turned on. That is to say, the system leaves the power down mode.
In the prior art, the input receiving circuit 102 has either larger power consumption, or worse noise immunity. Therefore, how to design a better input receiving circuit becomes an important issue for an integrated circuit designer.

Input receiver and operation method thereof