An ATM concentrator connects (mxc3x97n) input highways to n output highways and performs a full priority control. The ATM concentrator has output cell buffers for respective quality classes. Cells are read from the output buffers of the quality classes and the number of valid cells thereof is checked. A quality class c is determined with respect to which an accumulated value of the numbers of valid cells calculated successively from quality classes of higher priority is maximum within the total number of the output highways. The ATM concentrator outputs only cells of the highest priority class if the quality class c is the highest priority class. When the quality class c is not the highest priority class, the ATM concentrator writes valid cells of next priority class through the quality class c over cells that are not valid cells in the highest priority class.

1. Field of the Invention
The present invention relates to a traffic priority control system for a concentration-type ATM (Asynchronous Transfer Mode) switch which is used in an ATM exchange, an ATM cross-connect apparatus, or the like, and more particularly to an ATM concentrator for achieving traffic priority control while preventing a reduction in the throughput of transmitted cells of low priority class with a plurality of output cell buffers for priority classes.
2. Description of the Prior Art
For ATM communications, an information signal such as an audio, video, or data signal is digitized and stored in the payload of an ATM cell that is 53 bytes long, and an ATM traffic composed of the ATM cells is transmitted.
Audio, video, and data signals have different information rates (i.e., transmission bands) and different allowable transmission delay times. Therefore, users of these signals pose different requirements for the qualities of services (QoS) of ATM networks, such as transmission band assurances and transmission delay assurances, with respect to audio, video, and data traffic. For example, users want to reduce any transmission delay for audio and video traffic because if the transmission delay were too large, audio and video signals reproduced from ATM cells at a receiver would be unnatural to the users. On the other hand, low-rate data traffic keep their qualities from being lowered even when their transmission delay is somewhat large.
There is known a priority control system for controlling the transmission of information signals depending on a number of quality classes established with respect to different requirements for transmission delays and transmission bands of the information signals. According to the priority control system there are established, more specifically, quality classes for traffic comprising ATM cells of information signals, and one of the quality classes is assigned to an ATM cell depending on connection numbers such as VPI (Virtual Path Identifier) and VCI (Virtual Connection Identifier) and a CLP (Cell Loss Priority) bit that are contained in the header of the ATM cell. In a buffer of an ATM exchange or an ATM cross-connect, the quality class of the ATM cell for a connection is determined depending on the VPI, the VCI, and the CLP bit in the header of the arrived ATM cell, and the ATM cell is controlled for transmission depending on the determined quality class.
One example of such a priority control system will be described below with reference to FIG. 1. FIG. 1 shows an ATM cell buffer system having a single input highway and a single output highway. There are established two quality classes with respect to transmission delays, i.e., a high priority class (class 1) and a low priority class (class 2) for ATM cells. The ATM cell buffer system has a cell buffer 33 for storing ATM cells of the high priority class and a cell buffer 34 for storing ATM cells of the low priority class. The cell buffers 33, 34 are connected to the input highway through respective connection filters 31-1, 31-2. The connection filters 31-1, 31-2 refer to the VPI, the VCI, and the CLP bit of each ATM cell that has arrived from the input highway to determine the quality class of each ATM cell, and transfers valid cells of determined quality classes to the respective cell buffers 33, 34. For example, if an ATM cell that has arrived at the connection filter 31-1 is of the high priority, then the connection filter 31-1 stores the ATM cell in the cell buffer 33, and if an ATM cell of the low priority has arrived, then the connection filter 31-2 stores the ATM cell in the cell buffer 34. The cell buffers 33, 34 have respective output terminals connected to a readout controller 32 which reads ATM cells from the cell buffers 33, 34.
According to a process of determining a sequence to read ATM cells in the readout controller 32, as disclosed in Japanese laid-open patent publication No. 4-220834 (JP, A, 04220834) (column 7, lines 9 to 14), for example, the readout controller 32 attempts to read ATM cells from the cell buffer 33 for the high priority class, and if the number of ATM cells stored in the cell buffer 33 is zero, then the readout controller 32 attempts to read ATM cells from the cell buffer 34 for the low priority class. Such a process is referred to as full priority control. The full priority control is advantageous in that it allows the readout controller 32 to carry out a simple control process and is applicable to high-speed circuits.
An ATM concentrator will be described below. An ATM concentrator is an ATM switch for connecting a plurality of input highways to a fewer number of output highways than the input highways. An (mxc3x97nxe2x88x92n) ATM concentrator connects (mxc3x97n) input highways to n output highways. For example, as disclosed in Japanese laid-open patent publication No. 7-66827 (JP, A, 07066827) (see FIG. 1 thereof), if an ATM exchange or an ATM cross-connect which has (mxc3x97n) input highways and (mxc3x97n) output highways is to be constructed with m basic modules having n input highways and n output highways and a single connection module, an (mxc3x97nxe2x88x92n) ATM concentrator is used for connecting (mxc3x97n) input highways to n output highways in the connection module.
FIG. 2 shows a conventional (mxc3x97nxe2x88x92n) ATM concentrator. An (mxe2x88x921) selector serves to select one of m highways, and n pieces of (mxe2x88x921) selectors 11-1 to 11-n are connected to (nxc3x97m) input highways. A counter 12 is connected to control the (mxe2x88x921) selectors 11-1 to 11-n to select one of the input highways. Output signals from the (mxe2x88x921) selectors 11-1 to 11-n are supplied through respective connection filters 36-1 to 36-n to a routing decision circuit 13. The routing decision circuit 13 has output terminals connected to a routing network 14 of an (nxc3x97n) Banyan switch. The routing network 14 has n output terminals connected through respective output cell buffers 35-1 to 35-n, each comprising an FIFO (First-In First-Out) memory, to n output highways.
Input signals from the (nxc3x97m) input highways are multiplexed into n signals, whose speed is m times the speed of the input signals, by the (mxe2x88x921) selectors 11-1 to 11-n. Specifically, if the speed of an input signal from an input highway is represented by V, then the speed of a signal outputted from an (mxe2x88x921) selector is represented by mV. Based on a signal generated by the counter 12, the (mxe2x88x921) selectors 11-1 to 11-n are operated in synchronism each other for synchronized multiplex timing. The n multiplexed signals are delivered to the connection filters 36-1 to 36-n, respectively, which refer to the VPI, the VCI, or the CLP bit in the header of each ATM cell to decide whether the ATM cell is a valid cell of a passing connection to pass through the ATM concentrator or not. If the ATM cell is a valid cell of a passing connection, then the connection filters 36-1 to 36-n send the valid cell to the routing decision circuit 13. If the ATM cell is not of a passing connection or it is an invalid cell of a passing connection, then the connection filters 36-1 to 36-n write the ATM cell over an idle cell or an invalid cell.
The routing decision circuit 13 and the routing network 14 serve to hold sequences of arrival of valid cells from the same input highways and store valid cells uniformly in the output cell buffers 35-1 to 35-n for thereby preventing valid cells from concentrating on and hence overflowing some of the output cell buffers 35-1 to 35-n. Based on the known function of the Banyan switch for sorting a monotonous signal string into a continuous signal string without blocking, the routing decision circuit 13 and the routing network 14 shift and output valid cells, one by one, successively from highways of smaller numbers, and shift effective cells arriving in a next cell slot from a highway represented by the sum of 1 and the maximum highway number of the highway which has outputted valid cells in a preceding cell slot. When the highway number reaches its maximum value n, the routing decision circuit 13 and the routing network 14 control the highway number to go back to the first highway. Idle cells and invalid cells are outputted to a highway which is free of valid cells. A j-th highway will hereinafter be represented by xe2x80x9cHWjxe2x80x9d.
If four valid cells are simultaneously inputted to odd-numbered highways HW1, HW3, HW5, HW7 of the routing decision circuit 13 when n=8, then the routing network 14 outputs valid cells at the highways HW1, HW2, HW3, HW4. If seven valid cells are simultaneously inputted to the routing decision circuit 13 in a next cell slot, then the routing network 14 outputs valid cells at the highways HW5, HW6, HW7, HW8, HW1, HW2, HW3. The routing network 14 transmits ATM cells at a speed mV which is m times the input signal speed V to the output cell buffers 35-1 to 35-n, each of which stores m ATM cells in one cell slot. The output cell buffers 35-1 to 35-n store input cells even when they are idle cells or invalid cells other than valid cells. ATM cells are read from the cell output positions of the output cell buffers 35-1 to 35-n in each cell slot. Even if cells stored in the output cell buffers 35-1 to 35-n are idle cells or invalid cells, they are read from the output cell buffers 35-1 to 35-n.
FIG. 3 shows a conventional ATM concentrator for carrying out the full priority control with quality classes established. The ATM concentrator shown in FIG. 3 is similar to the ATM concentrator shown in FIG. 2 except that a high priority class (class 1) and a low priority class (class 2) are established with respect to transmission delays for full priority control. A cell stream from (nxc3x97m) input highways is supplied simultaneously to a sorting unit 1 for the high priority class and a sorting unit 2 for the low priority class. Each of the sorting units 1, 2 serves to concentrate the (nxc3x97m) input highways to n output highways. The sorting unit 1 for the high priority class has n output terminals connected respectively to output cell buffers 3-1 to 3-n for the high priority class. The numbers of valid cells stored in the output cell buffers 3-1 to 3-n are held by a valid cell number table 4. Similarly, the sorting unit 2 for the low priority class has n output terminals connected respectively to output cell buffers 6-1 to 6-n for the low priority class. The numbers of valid cells stored in the output cell buffers 6-1 to 6-n are held by a valid cell number table 7. A selector 39 serves to select n out of 2n highways from the output cell buffers 3-1 to 3-n, 6-1 to 6-n. A readout controller 38 refers to the valid cell number tables 4, 7 to control the reading of cells in the selector 39.
An example of each of the sorting units 1, 2 is shown in FIG. 4. The sorting unit shown in FIG. 4 is similar to a block 37, indicated by the dotted lines, of the ATM concentrator shown in FIG. 2 except that the connection filters 36-1 to 36-n shown in FIG. 2 are replaced with connection quality class filters 15-1 to 15-n which function as both connection filters and quality filters. The connection quality class filters 15-1 to 15-n refer to the VPI, the VCI, or the CLP bit in the header of each ATM cell to decide whether the ATM cell is an valid cell of a passing connection to pass through the sorting unit or not. If the ATM cell is an valid cell of a passing connection, then the connection quality class filters 15-1 to 15-n determines the quality class of the valid cell, i.e., decides whether the quality class is the class 1 or the class 2, based on the VPI, the VCI, or the CLP bit. If the ATM cell is an valid cell of the quality class to pass through the sorting unit 1 or 2, then the connection quality class filters 15-1 to 15-n send the valid cell to the routing decision circuit 13. If the ATM cell is not of a passing connection or it is an invalid cell of a passing connection, or if it is a valid cell of a passing connection but is not of the quality class to pass through the sorting unit, then the connection quality class filters 15-1 to 15-n write the ATM cell over an idle cell or an invalid cell. Consequently, the ATM concentrator shown in FIG. 3 selects ATM cells having predetermined VPI, VCI, and CLP bit and a predetermined quality class from input signals supplied from the (nxc3x97m) input highways, and supplies the selected ATM cells to the n highways. The ATM concentrator outputs ATM cells at a speed which is m times the speed at which they are inputted to the ATM concentrator.
Operation of the (mxc3x97nxe2x88x92n) ATM concentrator shown in FIG. 3 which has the full priority control capability will be described below. When ATM cells arrive at the ATM concentrator, the sorting units 1, 2 sort, for respective quality classes, those ATM cells having predetermined VPI, VCI, and CLP bit. If ATM cells are valid cells of the high priority class, then they are sorted by the sorting unit 1, and stored in the output cell buffers 3-1 to 3-n for the high priority class at a speed which is m times the speed at which the ATM cells are inputted. Likewise, if ATM cells are valid cells of the low priority class, then they are sorted by the sorting unit 2, and stored in the output cell buffers 6-1 to 6-n for the low priority class at a speed which is m times the speed at which the ATM cells are inputted.
The number of valid cells among a total of n ATM cells to be read from the output cell buffers 3-1 to 3-n at a next readout time is counted and written in the valid cell number table 4 for the high quality class. Similarly, the number of valid cells among a total of n ATM cells to be read from the output cell buffers 6-1 to 6-n at a next readout time is counted and written in the valid cell number table 7 for the low-quality class.
The selector 39 reads ATM cells, one by one, from the cell output positions of the output cell buffers 3-1 to 3-n for the high-quality class in each output selector slot. At the same time, the readout controller 38 reads the number of valid cells among ATM cells at the cell output positions of the output cell buffers 3-1 to 3-n from the valid cell number table 4. The readout controller 38 checks if the number of valid cells of the high priority class is 0 or not. If the number of valid cells of the high priority class is 1 or more, then the readout controller 38 outputs a select signal to the selector 39 to output n pieces of the ATM cells read from the output cell buffers 3-1 to 3-n. If the number of valid cells of the high priority class is 0, then the readout controller 38 outputs a select signal to the selector 39 to output ATM cells from the output cell buffers 6-1 to 6-n for the low quality class.
Therefore, if a select signal received from the readout controller 38 represents the selection of the class 1 (high priority class), then the selector 39 outputs the n ATM cells read from the output cell buffers 3-1 to 3-n for the high quality class, one by one, to the n output highways. If a select signal received from the readout controller 38 represents the selection of the class 2 (low priority class), then the selector 39 reads ATM cells from the cell output positions of the output cell buffers 6-1 to 6-n for the low quality class, and outputs n ATM cells, one by one, to the n output highways.
The conventional ATM concentrator shown in FIG. 3 is disadvantageous in that if the n ATM cells read from the output cell buffers 3-1 to 3-n for the high priority class which corresponds to a high quality class include even one valid cell, then the ATM concentrator does not output any ATM cells of a quality class lower than the high quality class, with the result that the throughput of the ATM concentrator will not increase. This is because when ATM cells arrive at such an interval that k valid cells (k is an integer in the range of 1xe2x89xa6k less than n) are always stored in any of the output cell buffers 3-1 to 3-n for the high priority class, the k valid cells are outputted from only the output cell buffers 3-1 to 3-n, but valid cells of the class 2 stored in the output cell buffers 6-1 to 6-n are not outputted at all, and idle cells and invalid cells are outputted from (nxe2x88x92k) of the output highways of the ATM concentrator whereas valid cells are transmitted through k highways.
For example, when ATM cells arrive at such an interval that while valid cells of the class 2 arrive highly frequently at the ATM concentrator, valid cells of the class 1 arrive less frequently at the ATM concentrator though one valid cell of the class 1 is always stored in any one of the output cell buffers 3-1 to 3-n, valid cells are outputted from only the output cell buffers 3-1 to 3-n, but any valid cells of the class 2 stored in the output cell buffers 6-1 to 6-n are not outputted at all, and idle cells and invalid cells are outputted from (nxe2x88x921) of the output highways of the ATM concentrator whereas valid cells are transmitted through only one highway. As a result, the utilization factor of the highways does not increase, and the throughput of the ATM concentrator does not increase.
It is, therefore, an object of the present invention to provide an ATM concentrator of an (mxc3x97nxe2x88x921) configuration which has output cell buffers assembled together into as many groups as the number of quality classes established for ATM cells, for carrying out full priority control for outputting valid cells of a higher priority class in preference to valid cells of a lower priority class, the ATM concentrator being capable of multiplexing and outputting valid cells of both the higher and lower priority class when the number of valid cells of the higher priority class in n output highways is small, for thereby increasing the utilization factor of the highways and the ATM concentrator throughput.
According to the present invention, the above object can be accomplished by an ATM concentrator having (mxc3x97n) input highways and n output highways and established CL quality classes ranging from a quality class 1 of highest priority to a quality class CL of lowest priority, for performing a priority control process for outputting cells of a quality class of relatively high priority in preference to cells of a quality class of relatively low priority, where each of m, n, CL is an integer of 2 or greater, comprising:
output cell buffers for the respective quality classes, associated respectively with the output highways;
a readout controller for checking the number of valid cells of cells read from the n output highways for each of the quality classes, determining a quality class c with respect to which an accumulated value of the numbers of valid cells calculated successively from quality classes of higher priority is maximum within the total number n of the output highways, generating a multiplexing control signal to instruct the output cell buffers of the quality class 1 to output n cells if the determined quality class c is the quality class 1, and checking highways corresponding to valid cells of cells read from the output cell buffers of the quality classes 2 through c and generating a multiplexing control signal to instruct writing of valid cells of the quality classes 2 through c over highways corresponding to cells which are not valid cells, of cells read from the output cell buffers of the quality class 1, if the determined quality class c is a quality class other than the quality class 1; and
a quality class multiplexer for outputting n cells read from the output cell buffers of the quality class 1 according to the multiplexing control signal or outputting a total of n cells produced by multiplexing the valid cells read from the output cell buffers of the quality classes 2 through c with n cells read from the output cell buffers of the quality class 1 based on the multiplexing control signal, to the n output highways;
whereby priority control of the quality class of relatively high priority and the quality class of relatively low priority can be carried out based on the multiplexing control signal generated by the readout controller.
The above and other objects, features and advantages of the present invention will become apparent from the following description with reference to the accompanying drawings which illustrate examples of the present invention.

Traffic priority control system for a concentration-type ATM switch


A method and system that detects mirrored host pairs using information about a large set of pages, including one or more of: URLs, IP addresses, and connectivity information. The identities of the detected mirrored hosts are then saved so that browsers, crawlers, proxy servers, or the like can correctly identify mirrored web sites. The described embodiments of the present invention use one or a combination of techniques to identify mirrors. A first group of techniques involves determining mirrors based on URLs and information about connectivity (i.e., hyperlinks) between pages. A second group of techniques looks at connectivity information at a higher granularity, considering all links from all pages on a host as one group and ignoring the target of each link beyond the host level.

The present invention relates generally to a method and apparatus for finding mirrored hosts and, specifically, to a method and apparatus for finding mirrored hosts by analyzing connectivity and naming structures of the host and of the web pages of the host.
In recent years, the World Wide Web (xe2x80x9cthe webxe2x80x9d) has grown hugely in popularity and use. Currently, almost any type of information can be found on the web if one knows where to look. Knowing where to look has increasingly become problematic because the number of web sites that make up the web have grown at an astounding rate since the early 1990s. In recent years, increasingly sophisticated software, such as search engines and web browsers have been developed that allow users of the web to locate information in the web. Other software, such as proxy servers improve the speed and security of web usage.
A web crawler is a software program that fetches a set of pages from the web by following hyperlinks between the pages. Search engines, such as Compaq Computer Corporation""s AltaVista search engine, employ crawlers to build the web page indexes used by the search engine. Web browsers are applications that fetch and display web pages to a user. Proxy servers (proxies) fetch web pages from web server systems on behalf of web browsers. For efficiency reasons, proxies and browsers sometimes cache web pages (that is, store their content locally). Thus, if a cached page is requested a second time, it can be retrieved from a local cache.
A page in the web is accessed by its web address, also called a Uniform Resource Locator (URL). The URL of a web page has three parts: 1) an access type (such as xe2x80x9chttpxe2x80x9d) 2) a host name, which identifies the host on which the page is stored, and 3) a path, which specifies a location within the host. A web site is made up of one or more web pages. As shown in FIG. 7, the format of a URL of a web page looks like:
 less than access type greater than :// less than host greater than / less than path greater than
where  less than host greater than  is the name of the web server that stores the web site and  less than path greater than  is the path of the page within the web server.
It has become increasingly common to duplicate all or part of certain popular web sites. For example, download hosts for certain popular software are often xe2x80x9cmirroredxe2x80x9d so that users can obtain the same downloadable software from any one of the mirrored hosts. Mirroring is the systematic replication of content across hosts. Mirroring happens when distinct hosts provide access to copies of the same data. Because mirrored hosts allow users to obtain the same information from any of the mirrored hosts, mirroring helps avoid bottlenecks at popular hosts. Hosts are mirrored for a variety of other reasons. Mirrored hosts may have identical page structures or they may contain only certain pages and page structures that are identical. In this document, two separate tests are used when determining mirrors. In a first test, two hosts, A and B are xe2x80x9cmirrorsxe2x80x9d if and only if for every document on host A there is a highly similar document on B with the same path and vice versa. A second test categorizes pairs of hosts according to a plurality of mirroring categories, where the categories represent degrees of miroring. The two hosts do not have to be exactly matched in structure and/or content to be mirrored hosts.
Crawlers, search engines, and proxy servers all fetch large numbers of pages on the web. If these programs could detect mirroring in hosts, they could refrain from fetching content from all but one of the mirrored hosts, thus reducing the number of pages fetched and improving their overall performance. Given a large list of URLs encountered on the web (such as a list collected by a crawler of the list of URLs viewed by a central proxy of a large Internet Service Provider) it is desirable to be able to determine which hosts are mirrored. Some specific examples are provided below.
Often search engines index only one copy of a mirrored page. In the process, they may fetch replicas and discard them. If mirroring information were available, a search engine could avoid fetching replicas from known mirrored hosts. The search engine could also distribute fetches of the remaining pages between the mirrors for load balancing, or choose the best mirror in terms of response time.
Proxy servers and web browsers maintain cached copies of downloaded pages to avoid re-fetching. The effectiveness of such caches can be increased if mirroring information is available. When a URL needs to be fetched, the cache is first checked. If a requested page has not yet been fetched, but it is determined that a page from a mirrored host with the same path has been fetched and is available in the cache, the cached mirror page can be used instead of fetching the requested page.
Thus, the ability to identify mirrored hosts would improve the speed and efficiency of operation of software accessing the world wide web.
Certain conventional web crawling software are able to identify some mirrored web sites by using Domain Name Server (DNS) lookup. When a crawler fetches a URL, it needs to first convert the hostname of the URL to a corresponding Internet Protocol (IP) address to establish a network connection. Such lookups are done using a service known as DNS. A DNS lookup returns one or more IP address for each hostname. Crawlers usually treat hosts that have an IP addresses in common as mirrors to avoid redundant fetching. This method does not always identify all mirrored hosts and may mis-identify some hosts as mirrored that are not mirrored. For example, a xe2x80x9cvirtual hostxe2x80x9d is a host that hosts more than one web site but has a single IP address. The web sites hosted by a virtual host web server, while all having the same IP address are not necessarily mirrors. Similarly, not all mirrored hosts share a common IP address. In addition, some hosts may have more than one IP address. Thus, IP matching alone is not always sufficient to prove that two hosts are mirrors of each other.
The described embodiment of the present invention addresses not only the problem of finding identical mirror hosts, but also the problem of finding hosts that are not completely identical, but contain a significant amount of shared content. This information is useful in understanding the composition of the web and the collaborations ongoing between principals on the web.
The described embodiment of the invention detects mirrored host pairs using information about a large set of pages, including one or more of: URLs, IP addresses, and connectivity information. The identities of the detected mirrored hosts are then saved so that browsers, crawlers, proxy servers, or the like can correctly identify mirrored web sites. The described embodiments of the present invention use one or a combination of techniques to identify mirrors. A first group of techniques involves determining mirrors based on URLs and information about connectivity (i.e., hyperlinks) between pages. A second group of techniques looks at connectivity information at a higher granularity, considering all links from all pages on a host as one group and ignoring the target of each link beyond the host level.
In accordance with the purpose of the invention, as embodied and broadly described herein, the invention relates to a method of determining mirrored web sites, comprising: receiving information about a plurality of web sites stored on a plurality of hosts; determining a list of host pairs that are potentially mirrored hosts; and analyzing the list of pairs of potential mirrored hosts to determine which of the host pairs are mirrored hosts.
In further accordance with the purpose of the invention, as embodied and broadly described herein, the invention relates to a method of determining mirrored web hosts, comprising: receiving information about the IP addresses of a plurality of web sites stored on a plurality of hosts; determining clusters of hosts, where all web sites in a cluster have the same IP addresses; and determining that the hosts in clusters of hosts having less than or equal to a threshold number of hosts therein are mirrored web hosts.
In further accordance with the purpose of the invention, as embodied and broadly described herein, the invention relates to a method of determining mirrored web hosts, comprising: receiving information about the addresses of a plurality of web sites stored on a plurality of hosts and about page level connectivity information of the plurality of web sites and a list of potentially mirrored hosts pairs; and filtering the list of potential mirrored hosts pairs in accordance with the page level connectivity information.
In further accordance with the purpose of the invention, as embodied and broadly described herein, the invention relates to a method of determining mirrored web hosts, comprising: receiving information about the addresses of a plurality of web sites stored on a plurality of hosts and about connectivity information of the plurality of web sites; for each host, determining a set of terms for the host, indicating those hosts that are targets of incoming links from some page on the host; for each term, determining the frequency, which equals the number of such incoming links; for each host, selecting the terms with the highest frequency; for each host, weighting the terms; and using term vector matching to determine the likelihood of a pair of hosts being mirrors in accordance with the weighted terms of the pair of hosts.
Advantages of the invention will be set forth in part in the description which follows and in part will be obvious from the description or may be learned by practice of the invention. The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims and equivalents.

Method and apparatus for finding mirrored hosts by analyzing connectivity and IP addresses


A vent is disclosed for a screw mounted support shaft of a fluid dynamic bearing for a spindle of a magnetic disk file. The support shaft for mounting a spindle bushing has an axial hollow center internally threaded at one end, and has upper and lower bearing journals for rotatably mounting the spindle bushing with a fluid lubricant. The bearing journals are separated by a recess having a vent passage between the recess and hollow center. A screw is threaded through the base plate or cover into the threaded end of the support shaft, mounting the support shaft to the base plate or cover. An air vent passage, such as a slit is provided axially either in the threaded end of the hollow center of the support shaft or in the screw, and radially across the end of the support shaft so the air bleed passage extends from the hollow center externally of the support shaft.

Magnetic disk files provide primary data storage systems for computer systems. The data is recorded in concentric tracks of a magnetic disk in the form of magnetic transitions. The disks are mounted on a spindle and the information is accessed by an actuator which moves a magnetic transducer radially over the surface of the disk and aligns the transducer with the concentric tracks. The disk and spindle are mounted for rotation on a support shaft and the disks are rotated at high speeds by means of an electric motor.
Important requirements for magnetic disk files are quick access to data together with high data rates. A key to both is a high rotational speed. On average, it takes half a revolution of the disk for the desired data to reach the transducer after the actuator has positioned the transducer at the desired track. Thus, the higher the speed the disk rotates, the quicker the desired data can be accessed. Similarly, faster rotation of a disk causes more data to pass the transducer, increasing the data rate at the transducer.
Fluid dynamic bearings may be used to achieve faster rotation speeds. In these systems, a lubricating fluid, such as oil, functions as the actual bearing surface between the stationary support shaft and the rotating spindle.
Typically, the lubricating fluid is maintained in the bearing areas by means of surface tension seals and a careful balance between the surface tension of the lubricant, the relative pressures of the air and the lubricant, and the size and structure of the clearances at the edges of the bearings.
For magnetic disk drive spindles, two fluid dynamic bearings are typically required with one at the top and one at the bottom of the spindle, respectively The bearings are held in place by surface tension, but are sometimes subject to rupturing by entrapped air and are therefore vented to avoid rupturing the oil film. The entrapped air can occur in low pressure and/or high temperature conditions. When the support shaft for the spindle is hollow and is press fitted into a hole in a disk file base plate, the entrapped air then vented out through the press fit hole in the base plate.
Referring to FIG. 1, an example of the described fluid dynamic spindle bearing 10 of the prior art is illustrated with two journal bearings 12 and 14. A spindle bushing 16 is mounted on a support shaft 16 with a small clearance. The small clearance is filled with a fluid lubricant, such as oil, through which fluid dynamic pressure is generated as the spindle bushing is rotated. The lubricating fluid is maintained in the bearing journals 12 and 14 by means of surface tension seals employing a careful balance between the surface tension of the lubricant, the relative pressures of the air and the lubricant, and the size and structure of the clearances at the edges of the bearings.
Two fluid dynamic bearings 12 and 14 are employed toward the top and bottom of the magnetic disk drive spindle, respectively. A recess 20 is provided defining or separating the bearing journals 12 and 14. The illustrated bearings 12 and 14 are normally coupled. If coupled, the bearings are sometimes decoupled by entrapped air, risking rupturing the oil film surface tension seals. The rupturing can occur due to expansion of the entrapped air due to low external ambient pressure and/or high temperature conditions. The bearings 12 and 14 may include a venting hole to the hollow center opening 23 in the support shaft 18 to reduce the likelihood of rupturing the oil film surface tension.
Alternatively, the bearings may be initially decoupled, forming surface tension seals at the top and bottom of each bearing 12 and 14. In the case of decoupled bearings, air is already present between the two radial bearings, but sometimes additional air can be entrapped during assembly or oil charging or even during operation. Thus, venting is often necessary to avoid rupturing the oil film. The venting hole 22 is therefore provided to vent the entrapped air through the hollow center opening 23 in the support shaft 18.
The support shaft 18 is press fit into an opening in a base plate 25. The press fit provides an external vent for the center opening 23 of the support shaft. Press fitting of the support shaft into the press fit hole in the base plate can be an expensive arrangement requiring accurate machining of the hole.
A more easily manufacturable alternative may be a screw mount through a flat base plate into the bottom of the support shaft 18. Unfortunately, the venting function is impeded by the presence of the screw and the contact between support shaft 18 and base plate 25 even if venting hole 22 is provided. A hollow screw could be employed, but is not suitable from a cost perspective.

International Business Machines Corporation


An expert system for diagnosing data communication networks. The expert system operates according to a landmark data abstraction paradigm, wherein landmarks are interpretations of network data. The landmarks are indicators of network problems. The expert system diagnoses the data communication networks by detecting landmarks and then interpreting the detected landmarks to determine whether network problems exist.

1. Field Of The Invention
The present invention relates generally to expert systems, and more particularly to expert systems for diagnosing data communication networks.
2. Related Art
There are at least three types of network problems that occur in data communication networks: physical problems, connectivity problems, and configuration problems.
Physical problems include problems which induce noise on the network, or which physically and/or electrically impede communication on the network. For example, physical problems include defective or incorrectly installed cables and connectors. Physical problems also include cables which are too long or which are broken.
Connectivity problems include problems with spanning devices. For example, connectivity problems include malfunctioning and incorrectly installed repeaters, bridges, and routers.
Configuration problems include problems with configuring and programming devices on the network. For example, a configuration problem occurs when multiple devices are programmed with the same network address. Another configuration problem occurs when a device is programmed with an incorrect broadcast address.
Tools are used to diagnose data communication networks to identify network problems. Protocol analyzers are such tools.
With the tools, human operators may manually diagnose data communication networks. For example, operators may use protocol analyzers to statistically monitor the data communication networks to measure traffic levels, including broadcast traffic levels, and to detect collisions and errors.
Based on network information acquired through using the tools, operators may identify network problems. The operators may correct the network problems once such network problems are identified.
However, there are problems with manually diagnosing data communication networks. For example, novice operators may not have the knowledge and experience to differentiate between important and superfluous information. Thus, novice operators may collect large amounts of unneeded information. Also, novice operators may lack sufficient knowledge and experience to effectively and efficiently operate the tools. Further, novice operators may lack sufficient knowledge and experience to accurately and effectively use network information to detect network problems. Expert operators having sufficient knowledge and experience to effectively, accurately, and efficiently collect data, operate the tools, and detect network problems may not be available to diagnose the data communication networks.
Further, manual diagnosis of data communication networks may result in sporadic monitoring of the networks since such manual diagnosis can be performed only when a human operator is available. Thus, even if expert operators are available, manual diagnosis is not conducive for periodic diagnosis of data communication networks.
A prior solution to the above manual diagnosis problem is to use known expert systems to automatically diagnose data communication networks. Such known expert systems automatically control the tools (such as protocol analyzers) to collect network data. Based on the network data, the known expert systems automatically identify network problems.
However, there are problems with using known expert systems to automatically diagnose data communication networks. First, known expert systems, like novice operators, often collect large amounts of unneeded information.
Second, known expert systems often analyze and interpret the collected data in an inefficient and ineffective manner.
Third, known expert systems do not allow for human operator interaction and control. With known expert systems, operators send commands to initiate the known expert systems. However, once initiated, the known expert systems execute until they complete the operators' commands. The operators do not interact with the known expert systems (once the expert systems are initiated) because the known expert systems often do not provide operators with status information. The operators do not control the known expert systems because, once initiated, the known expert systems do not respond to operator commands.
Providing such operator interaction and control is important for both novice operators and expert operators.
For novice operators, such interaction and control is important for learning purposes. By providing novice operators with interaction and control, novice operators will learn how to control the tools and how to identify network problems.
For expert operators, such interaction and control is important for greater accuracy in the diagnosis process. By providing expert operators with interaction and control, expert operators may draw on their experience and knowledge to either confirm or modify the expert systems, operation. Such confirmation and modification will ultimately result in a more accurate and effective diagnosis process.
Therefore, an expert system for automatically diagnosing data communication networks, which efficiently and effectively collects, analyzes, and interprets data, and which allows for human operator interaction and control, is required.

Landmark data abstraction paradigm to diagnose data communication networks


An earthmoving apparatus collects windrows of loose material left behind during roadmaking via a ground tracking pick up head and without damaging the ground surface. The apparatus can be used for removing other types of loose material from the ground without damage to the ground.

This invention relates to a debris removing apparatus and particularly relates to an earth working apparatus for picking up windrows of loose material on a ground surface, such as a road surface.
When pavements such as roads, airports, industrial hardstandings, and the like, are constructed out of gravel, crushed rock, or other quarry products, graders are used to trim each layer to the required level, shape and texture.
Any surplus material is cut off by the grader and left in windrows, that is, rows of loose material sitting on top of the finished surface.
Currently, the task of removing this material is performed by either small elevating scrapers, or by front-end loaders. Neither of these existing machines are efficient since they spread and spill the loose material, necessitating the expensive and tedious repetition of the grading and grade checking operations. Also, as scrapers and front-end loaders are primarily designed for other tasks, these machines often cut and damage the finished surface which can change the level, shape and texture of the surface.
I have therefore designed an apparatus which can pick up loose debris such as the windrows of loose material on a ground surface and which can eliminate, or at least reduce, the disadvantages found with the use of scrapers and front-end loaders.
My apparatus can be used in other applications as well, such as for general removal of loose debris on a factory floor or other ground surface.


An intensifier is operable to supply force and includes a housing defining a cavity. A ram is slidably positioned within the cavity and partially extends from the housing. The ram is moveable between retracted and extended positions along a longitudinal axis. First and second links are rotatably coupled to one another about an axis of rotation and are selectively moveable between retracted positions where the axis of rotation is not axially aligned with the ram and partially extended positions where the axis of rotation is axially aligned with the ram. The intensifier includes a plurality of power pistons axially aligned with each other and the ram. The power pistons are selectively operable to provide an output force to the ram when the first and second links are in the partially extended positions.

The present disclosure generally relates to a fluid powered device to perform work. More particularly, a pneumatically powered intensifying cylinder is described.
The manufacturing industry utilizes various intensified fluid powered devices to perform work. Some of these devices may produce 100 or more tons of output force. One such device utilizes air at various input pressures to drive a piston and rod into a sealed hydraulic chamber. An intensified output force acts on a working piston rod. Pressures in excess of 6,000 psi may be generated in a sealed hydraulic chamber. Due to these high operating pressures, seals may require replacement from time to time. Furthermore, such systems may also be subject to air entering into the hydraulic chamber. The accumulated air may adversely affect the performance of the cylinder and may require purging from the system.
Some intensified fluid powered devices include springs to return internal pistons. The springs may be subject to breakage and may have a potential to damage the cylinder should breakage occur. Furthermore, special valving is required to sequence the operation of the various components of the intensified fluid powered device. To obtain a desired output force, some models require an input pressure of approximately 145 psi to be supplied. Accumulators or special air compressors may be required to provide this magnitude of input pressure.
Another high force output device that operates with an input of relatively low pressure air is known as an air toggle press. This simple device produces a greatly magnified force output through a toggle linkage mechanism. However, the air toggle press does not produce a straight-line constant force output that may be desirable in some applications. The seals and the cylinder of the air toggle press are exposed to relatively low pressures only.
Many of the previously described assemblies may require anti-rotation devices to maintain proper orientation of certain components during the work stroke. These devices may be added either internally or externally depending on unit design and space constraints.


An auxiliary filter assembly is for use in a skimmer of residential swimming pools. The assembly comprises an adaptor collar and a cleanable filter basket. The adaptor collar is substantially flat and is for placement on a rim of a below water surface opening within the skimmer. The cleanable filter basket is made of a water porous material. The filter basket has an open top with a substantially rigid stabilizing ring permanently positioned in an edge defining the open top. The ring is dimensioned to rest on the adaptor collar. Swimming water debris is trapped in the filter basket as pool water is pulled through the filter basket on its way to a primary filter apparatus. The filter basket is easily separated from the adaptor collar, cleaned as needed and replaced.

Residential swimming pools are not uncommon. They can be above ground pools or in ground pools. Typically, the above ground pools hold about 3,000 gallons to about 15,000 gallons water and the in ground pools hold about 10,000 gallons to about 30,000 gallons water. In all cases, the water must be run through a filter apparatus to remove debris, including airborne material such as fallen leaves, other plant material, insects, and material brought into the pool by the swimmer such as hair and lint.
The typical pool has a water intake line which draws water from at least the surface of the pool and ideally from both the surface and the bottom of the pool. The water at the surface level is initially pulled into a skimmer and passed through a skimmer basket. The skimmer basket is a rigid mesh basket which filters out larger debris, e.g. leaves. The water then is conveyed by a pipeline to a primary filter apparatus to filter out more minute debris. There are different filter apparatus. Sand or diatomaceous earth are common filter medias. Periodically, the filter media in the filter apparatus becomes clogged and must be replaced. This involves a fairly arduous task of disassembling the filter apparatus, removing the filter media, discarding the filter media, adding fresh filter media to the filter apparatus, and reassembling the filter apparatus. Needless to say, the typical swimming pool owner would rather be swimming.
There is a need for a filter system to lessen or even eliminate the current necessity of periodic replacing of filter media in the filter apparatus. In accord with the need, there have been developed pre-main filter apparatus systems. U.S. Pat. Nos. 5,202,020 and 5,672,271 disclose devices for placement in the swimming pool's skimmer basket. The device of U.S. Pat. No. 5,202,020 appears costly to manufacture. The device of U.S. Pat. No. 5,672,271 appears difficult to use.
In accord with a continued need for a pre-primary filter apparatus filtering system, there has now been developed an assembly for use in the pool's skimmer. The assembly is economical to produce, easy to use and efficient in operation. The assembly of the invention effectively filters debris from the swimming pool water before it reaches the pool's primary filter assembly. The assembly is very conveniently cleaned and reused.

Auxiliary filter assembly for a swimming pool skimmer


There is provided an apparatus for compression testing. The apparatus has a base assembly having an end load element attached to the base assembly, the base assembly being rigid. The apparatus has a support assembly attached to the base assembly, and having a plurality of window portions. The apparatus has a core assembly installed within the support assembly, the core assembly being crushable and configured to protect the support assembly and the base assembly from fracture loads generated during compression testing. The base assembly, the support assembly, and the core assembly together form an apparatus for compression testing of a test specimen having a notch portion. The apparatus is configured for use with an optical strain measurement system. When the test specimen is installed in the support assembly, the test specimen and the notch portion are visible to the optical strain measurement system through the plurality of window portions.

1) Field of the Disclosure
The disclosure relates generally to apparatus assemblies, systems and methods for compression testing of test specimens, and more particularly, to apparatus assemblies, systems and methods for compression testing of large notch compression test panels, such as panels of component parts of air vehicles.
2) Description of Related Art
Mechanical testing of component parts, or of test specimens of component parts, is often performed in the manufacture of air vehicles, such as aircraft, rotorcraft, spacecraft, and other air vehicles. Mechanical testing provides material property data, such as strength, hardness ductility, and other data about the material as tested under various conditions, such as compression, tension, load and temperature. In turn, the mechanical testing provides information relating to the suitability of a material for its intended application. Such information aids in the design of component parts that will perform as expected.
Mechanical testing of component parts of air vehicles may include compression testing. Compression testing determines the behavior of materials, such as composite or metal materials, under compressive load conditions. Compression testing may be conducted by loading a test specimen, such as a test panel or a flat piece of laminate referred to as a "coupon", between two support plates of a test fixture.
The test fixture is typically installed in a testing machine, for example, a universal testing machine. The testing machine may apply a compression force or load to the test specimen and may compress the test specimen in a lengthwise direction until it fractures or breaks. The testing machine may record the force required to fracture or break the test specimen. Compressive strength of the test specimen material may be measured by plotting applied force or load versus deformation of the test specimen material. As used herein, "compressive strength" means the maximum compressive load or stress the test specimen material is capable of withstanding before fracturing or breaking.
Test fixtures, apparatus assemblies, and methods for compression testing of air vehicle component parts exist. For example, FIG. 1 is an illustration of a front perspective view of an existing test fixture 10 for compression testing, such as in the form of an existing large notch compression (LNC) test fixture 10a. As shown in FIG. 1, the existing test fixture 10 has a first support plate 12a and a second support plate 12b that sandwich a test specimen panel 28 therebetween. The test specimen panel 28 may be in the form of a large notch compression (LNC) panel.
As further shown in FIG. 1, the first support plate 12a and the second support plate 12b of the existing test fixture 10 completely cover the test specimen panel 28 and obstruct any view of the test specimen panel 28. Thus, use of such existing test fixture 10 precludes use with existing optical strain measurement systems that may be used to optically obtain information relating to strain measurements of the test specimen panel 28.
Instead of using existing optical strain measurement systems, the existing test fixture 10 requires the use of a plurality of strain gages 14 (see FIG. 1) to measure the strain of the test specimen panel 28. As shown in FIG. 1, each strain gage 14 may be positioned laterally across the first support plate 12a, and each strain gage 14 may be coupled to hinge attachment elements 16 mounted on a frame portion 18 of the existing test fixture 10.
However, the use of such strain gages 14 (see FIG. 1) may involve extensive installation time and labor, which results in increased flow time. In addition, the use of such strain gages 14 (see FIG. 1) may require precise alignment and calibration operations, as well as connection to a strain gage machine, prior to testing. This may, in turn, result in increased time and expense of testing. Due to the extensive time involved in installing the strain gages 14 (see FIG. 1) on the existing test fixture 10 (see FIG. 1), test specimen panels 28 may only be tested at a test rate of one (1) or two (2) test specimen panels 28 per day.
As further shown in FIG. 1, the existing test fixture 10 has a base portion 22 and a side support portion 24 (one on each side). However, the base portion 22 may be thin and wear out after several compression tests. Shimming may be required to reinforce the base portion 22 and to hold the first support plate 12a, the second support plate 12b, and the test specimen panel 28 in place. For example, shims 20 (see FIG. 1) may be installed on the existing test fixture 10 (see FIG. 1). However, such shimming process may involve extensive installation time and labor prior to testing. This may, in turn, result in increased time and expense of testing.
Thus, existing methods for compression testing of test specimen panels, such as large notch compression panels, may be expensive and may take four (4) to ten (10) weeks or more to complete. Accordingly, there is a need in the art for an improved apparatus, system and method for compression testing of test specimens, such as large notch compression test panels of component parts of air vehicles, that provide advantages over known apparatus assemblies, systems and methods.

Apparatus, system and method for compression testing of test specimens


A method and system utilized by a multi-processor computer for storing exponent codes is provided. The multi-processor computer includes a plurality of processing elements. Each processing element executes a task having an instruction set. The processing elements are assigned a position in an execution sequence that defines the order in which the processing elements generate their respective outputs. Instruction sets are stored in a computer memory attached to the processing elements. The instruction sets are stored so that the processing elements produce outputs according to the execution schedule. The computer memory can be accessed using a two-dimensional addressing scheme where one dimension designates processing elements and the other designates instructions. Each instruction set includes one or more exponent codes that cause a processing element to raise an input value to a specified power.

A dominant characteristic of a multiprocessor computer is that it is capable of concurrently executing a number of different software routines or "tasks". Typically, a program is broken down into one or more tasks, and each task is executed by a respective processing element. A multiprocessor computer has at least two processing elements. Although most common computers use a single processor, there are, in fact, many multiprocessor computers available today. The number of processing elements in each of these computers varies from two to 64,000.
As a result of executing a task, a processing element within a multiprocessor computer will generate one or more outputs. These outputs may be produced simultaneously with the outputs of other processing elements. In many circumstances, it is necessary to coordinate the generation of outputs among the processing elements. For example, in a situation where data dependency exists between two or more tasks, i.e., a successively executing task relies upon the outputs of one or more processing elements, it is necessary to synchronize the arrival of the data with the execution of the successive task.
One method currently used to synchronize the arrival of output data is polling. Using a polling method, a task waiting for data will individually poll each processing element to determine whether or not a respective output is available. Although this method allows the task to process the outputs in a coordinated fashion, it incurs a substantial amount of execution overhead. The task must repetitively execute a polling routine, which adds cost and complexity to the computer. Another method used to coordinate the arrival of outputs is the use of an interrupt processing scheme. Using this method, each processing element, upon generating an output, interrupts a successive task which is to receive the output. There are two drawbacks to using the interrupt method. First, the interrupt method adds substantial processing overhead to the computer. Second, the interrupt scheme adds considerable design complexity to the computer, which in turn increases its cost. A third technique taught by the prior art for coordinating the arrival of outputs of processing elements is to simply allow a successive task to wait until all the processing elements have generated their outputs. After the processing elements have finished generating outputs, the successive task receives the outputs and resumes execution. Such a technique is simple to implement; however, it will negatively effect the throughput of the computer because the successive task will be idle for large amounts of time waiting for data.
Thus, there exists a need for an improved method of coordinating the arrival of data outputs from processing elements in a multiprocessor system. Such a method should be simple to implement and improve the overall throughput of the multiprocessor system.

Method and system for storing exponent codes in a multi-processor computer to produce putputs according to an execution schedule


A system and method for authenticating a terminal in a communication system is described. The method includes executing a terminal authentication protocol, whereby the executing the terminal authentication protocol includes authenticating an identity of a network entity by a terminal in a communication system. The method further includes executing a challenge authentication protocol, wherein the executing the challenge authentication protocol includes sharing challenge data between the terminal and the network entity, and forming at the terminal, test data by at least applying one authentication function to the challenge data using the identifier. The executing the challenge authentication protocol further includes transmitting a message including terminal authentication data from the terminal to the network entity, and determining, based on the terminal authentication data, whether to provide the terminal with access to a service.

1. Field of the Invention
This invention relates to authentication protocols.
2. Description of the Related Art
Authentication protocols are used in communication networks to enable one entity in the network to satisfy another entity of its capacity to be provided with a service, for example the undertaking of a data transaction or the granting of access to a resource. For example, if a user's mobile telephone is to access an e-mail account on a remote server then the server may wish to authenticate the mobile phone so that it can be sure that it is making the contents of the account available to the correct entity. Similarly, the user of the mobile phone may want the phone to authenticate the server so that he can be sure that data that he provides to the server is not being intercepted by a third party who might be impersonating the server.
A number of authentication protocols have been developed.
The Extensible Authentication Protocol (EAP), described in [RFC2284], provides a standard mechanism for support of multiple authentication methods. Through the use of EAP, support for a number of authentication schemes may be added, including smart cards, Kerberos, Public Key, One Time Passwords, and others. Specific EAP/SIM and EAP/AKA methods have been defined for the purposes of the OWLAN system, which makes use of the GSM or UMTS authentication methods for the authentication of WLAN access and derivation of link keys for the protection of the WLAN link.
EAP is a general authentication protocol, designed to allow end-points to use multiple forms of authentication. EAP does not require the server (typically a PPP or IEEE 802 end-point) to authenticate the client itself, rather it allows the server to proxy authentication messages to a back-end authentication server, and inspect the packets to determine if the authentication was successful.
One of the goals of EAP is to enable the development of new authentication methods without requiring the deployment of new code on the local authentication server. As a result, the local server acts as a "passthrough", and need not understand specific EAP methods.
Since its deployment, a number of weaknesses in EAP have become apparent. These include lack of protection of the user identity or the EAP negotiation and no standardized mechanism for key exchange. For example, EAP/SIM and EAP/AKA solve these problems by making use of the specific features of SIM and USIM (AKA) authentication methods.
Recently IETF working groups have designed three new protocols to develop standard solutions. Two of them PEAP and TTLS, originating from the pppext working group, are intended to solve the same problem as EAP/SIM and EAP/AKA, but independently of the specific EAP method. The idea in brief is to encapsulate the EAP protocol within TLS. The third protocol PIC is developed by the ipsra working group, and it develops a unilateral version of the ISAKMP authentication and key derivation protocol, within which the EAP protocol is encapsulated. All three protocols include a method of managing secret parameters for further use. In PEAP and TTLS keys are derived from the TLS master key, while in PIC the tunnel derived by simplified ISAKMP is used to transport security association from the local authentication server to the client.
By wrapping the EAP protocol within TLS, Protected EAP (PEAP) claims to provide user anonymity and built-in support for key exchange.
FIG. 1 shows the relationship between the EAP peer (client), the network authentication server (NAS) and the backend authentication server. As described in the figure, the EAP conversation "passes through" the NAS on its way between the client and the backend authentication server. While the authentication conversation is between the EAP peer and the backend authentication server, the NAS and the backend authentication server need to have established trust for the conversation to proceed.
In PEAP, the conversation between the EAP peer and the backend server is encrypted and integrity protected within a TLS channel, and mutual authentication is required between the EAP peer and the backend server.
As a result, the NAS does not have knowledge of the TLS master secret derived between the EAP Peer and the backend authentication server, and cannot decrypt the PEAP conversation. In order to providing keying material for link-layer ciphersuites however, the NAS does obtain the master session keys, which are derived from the TLS master secret via a one-way function.
Since EAP methods may not know the link layer ciphersuite that has been negotiated, it may not be possible for them to provide link layer ciphersuite-specific keys. In addition, attempting to provide such keys is undesirable, since it would require the EAP method to be revised each time a new link layer ciphersuite is developed. As a result, PEAP derives master session keys, which can subsequently be truncated for use with a particular link layer ciphersuite. PEAP does not discuss the format of the attributes used to communicate the master session keys from the backend authentication server to the NAS; examples of such attributes are provided in [RFC2548].
The operation of PEAP is as follows:
1. Establish TLS connection. The TLS record protocol provides a secure connection between the peer and the back-end authentication server
2. Authenticate TLS server. The TLS handshake protocol is used for server authentication
3. Authenticate user. The user of the peer authenticates by tunnelling another EAP mechanism (e.g. Generic Token Card) inside the EAP-TLS connection. The back-end authentication server may have to contact another server to get the user authentication information validated.
4. Generate session keys. Using the TLS Pseudo-Random Function (PRF), the peer and the back-end server generate key material for use between NAS and peer.
5. (Transport session keys). The session key is transported from the server to the authenticator using e.g. Radius attributes and secure connection.
In a new internet draft, draft-buckley-pppext-eap-sim-gmm-00.txt, an application of PEAP to GSM authentication is presented. The architectural overview of this EAP method using SIM is depicted in FIG. 2.
The architectural view of EAP-TTLS is essentially the same as in PEAP, see FIG. 3. EAP-TTLS claims to allow legacy password-based authentication protocols to be used against existing authentication databases, while protecting the security of these legacy protocols against eavesdropping, man-in-the-middle and other cryptographic attacks.
EAP-TTLS also allows the client and server to establish keying material for use in the data connection between the client and access point. The keying material is established implicitly between the client and server based on the TLS handshake.
When record layer security is instantiated at the end of a TLS handshake, a pseudo-random function (PRF) is used to expand the negotiated master secret, server random value and client random value into a sequence of octets that is used as keying material for the record layer.
EAP-TTLS leverages this technique to create keying material for use in the data connection between client and access point. Exactly the same PRF is used to generate as much keying material as required, with the constant string set to "ttls keying material", as follows:
EAP-TTLS_keying_material=PRF(SecurityParameters.master_secret, ttls keying material",
SecurityParameters.client_random+SecurityParameters.server_random);
The master secret, client random and server random used to generate the data connection keying material must be those established during the TLS handshake. Both client and TTLS server generate this keying material, and they are guaranteed to be the same if the handshake succeeded. The TTLS server distributes this keying material to the access point via the AAA carrier protocol.
The PIC protocol is a method to bootstrap IPsec authentication via an "Authentication Server" (AS) and user authentication mechanisms (e.g., RADIUS), see FIG. 4. The client machine communicates with the AS using a key exchange protocol where only the server is authenticated, and the derived keys are used to protect the user authentication. Once the user is authenticated, the client machine obtains credentials from the AS that can be later used to authenticate the client in a standard IKE exchange with an IPsec-enabled security gateway. The later stage does not require user intervention.
The PIC protocol realizes this approach and secures it using simplified ISAKMP and IKE mechanisms. The protocol embeds EAP messages [RFC2284] in ISAKMP payloads to support multiple forms of user authentication. Once this user authentication succeeds, the client machine obtains from the AS credentials that can later be used by the client to perform regular IKE authentication with an IPsec-enabled gateway. PIC defines several forms of credentials and can be extended to support others. Note that this document uses the term "credentials" for both digital certificates and shared secret keys.
PIC requires no modification to IKE. Instead it uses simplified elements of ISAKMP and IKE to obtain a much less ambitious goal than general IKE, namely the secure provisioning of credentials for successfully authenticated users. The direct use of IKE, e.g. as compared to TLS tunneling [GETCERT], reduces complexity and contributes to the efficiency of the protocol.
The PIC protocol is defined between the Client and the AS. All other exchanges between the entities are implicit in the protocol. This applies in particular to user and machine authentication between the AS and the Back-End Authentication Server, and certification between the AS and the CA.
The four main stages of the proposed PIC protocol are:
1. An optional round of messages provides partial protection of the AS from denial-of-service attacks by verifying that the initiator of the exchange is reachable at the purported source IP address. This is done before any significant CPU or memory resources are consumed by the AS.
2. The protocol establishes a one-way authenticated channel from the client to the AS in which only the server is authenticated.
3. User authentication is performed over this secured channel. User authentication information is transported using EAP tunnelled within ISAKMP.
4. The AS sends the client a (typically short-term) credential, which can be used in subsequent IKE exchanges. This credential can be thought of as a certificate, or a private key generated or stored by the AS and accompanied by a corresponding certificate. It may also be a symmetric secret key, or other information for deriving such a key.
In stage 4 the created ISAKMP tunnel is used to obtain the secure provisioning of credentials for successfully authenticated users.
Another alternative proposal is HTTP digest authentication within a TLS tunnel, which is not described in detail here.
It should be noted that the network entity called "back-end server" in the description of PEAP, see FIG. 1, has not at all the same role in the authentication protocol as the back-end server in PIC has. The PEAP back-end server is called the EAP Server in FIG. 2 and its role is essentially the same as that of the TTLS AAA server of EAP-TTLS (FIG. 3) and the AS of PIC (FIG. 4).
The above proposals all utilise an inner client (or mutual) authentication protocol within a secure tunnel constructed using a session key resulting from an outer server authentication protocol. In the following description we use EAP/AKA as an example of the inner protocol. But the general points of the discussion are applicable to any pair of authentication protocols used in the above manner. This is convenient because the EAP/AKA protocol is to be implemented by the USIM of 3G mobile stations, and so this protocol is readily available to a terminal that is to be authenticated. EAP/AKA is a challenge-response protocol. In the protocol the "responding entity" which is to be authenticated shares a secret key with the "challenging entity" which is to verify its authenticity. The challenging entity issues to the responding entity a challenge message which includes challenge data, which is typically randomly generated data. The responding entity then generates response data by applying a known function to that challenge data and to the secret key. The response data is returned to the challenging entity in a response message. The challenging entity can also apply the known function to the challenge data and the key, and the result of that can be compared to the response data. Only if the two match is the responding entity is authenticated. In the above proposals the authentication method of AKA is to be used in just the same way as in its pre-existing applications: i.e. the terminal is supplied with challenge data to which it is to apply the function, and then it returns the result to the network for authentication. However, the key agreement part of UMTS AKA is not used.
In place of the EAP encapsulated AKA protocol any EAP type protocol can be used for authentication of the terminal to network.
FIG. 5 illustrates the logical architecture that is common to all of the above proposals. First, a stage-one authentication exchange 40 takes place. In that exchange the identity of a back-end server 41 is authenticated to a terminal entity 42. However, the identity of the terminal entity is not authenticated to the back-end server. Then a stage-two authentication exchange 43 takes place, in which it is intended that the terminal entity is authenticated to the back-end server. Since each of the proposals is intended to be compatible with existing terminal entities, the existing authentication protocol (e.g. EAP/AKA), which has hitherto been usable as a stand-alone protocol, is used for the essential authentication part of stage two. In stage two the back-end server issues a challenge 44 to the terminal entity. The challenge is of such a type that the back-end server can (either by itself or through referral to a further authentication server) authenticate the terminal by means of its response to the challenge. The terminal entity processes the challenge and formulates its response (step 45) and returns that response to the back-end server (step 46). Then the back-end server checks the response (or refers it for checking) (step 47). If the response is correct then the back-end server has authenticated the terminal entity and can issue it with credentials, e.g. session keys that allow it to carry out subsequent secure transactions with the server (step 48). Otherwise no such credentials are issued and the terminal entity cannot carry out such transactions.
Some of the stage-two protocols have both authentication function and key-agreement function. In existing proposals the key-agreement function of the stage-two protocol is not used. Instead, the session keys are derived using the key-agreement function of the stage-one authentication protocol.
Up to now it has been supposed that the above proposals provide for secure authentication of both the back-end server and the terminal entity to each other. However, the inventors of the present invention have observed that this is not the case.
The vulnerability of the above proposals will be described with reference to FIG. 6. In FIG. 6 like items are numbered as for FIG. 5. In FIG. 6 a "man-in-the-middle" (MITM) attacker 49, who intends to impersonate a terminal entity 42, takes the place of the terminal entity in FIG. 5. The MITM performs the stage-one authentication with the back-end server. Then during the stage-two authentication when it receives the challenge message (step 44) from the back-end server it forwards it on to the terminal entity 42. (Step 50) Using the pre-existing AKA protocol, it returns the appropriate response to the MITM. (Step 51). Then the MITM forwards that response to the back-end server. (step 46). Since the response is the correct response for authentication of terminal entity 42 the back-end server will authenticate the MITM as terminal entity 42 (step 47) and issue it with credentials accordingly (step 48). That may allow the MITM access to supposedly secure services, impersonating the identity of terminal entity 42.
The proposals described above have been developed with the aim of using the existing challenge-response protocol for the essential authentication part of stage two, since that is already a feature of the terminals that are to use the system. Since the proposals fail to provide adequate security, a new approach is needed.


A microfluidic refill includes a reservoir having a hollow body and an opening; a transport member in fluid communication with the reservoir; and a lid enclosing the opening of the reservoir. The lid is in fluid communication with the transport member. The lid comprises a rigid microfluidic delivery member. The rigid microfluidic delivery member includes a die and electrical traces that are in electrical communication with the die, wherein the electrical traces terminate at electrical contacts, wherein the electrical traces are disposed on only one plane. The die has a fluid chamber in fluid communication with the transport member at an inlet of the fluid chamber and with an orifice at an outlet of the fluid chamber and.

Various systems exist to deliver volatile compositions, such as perfume compositions, into the air by an energized (i.e. electrically/battery powered) microfluidic atomization. Recent attempts have been made to deliver scents using thermally activated microfluidic delivery systems, and, particularly, thermal inkjet systems. Some of these attempts are directed to printing ink-based scented fluids onto a substrate or surface medium using methods similar to those for printing ink onto a substrate or surface.
Thermal inkjet technology utilizes a replaceable cartridge that contains fluid and a micro-electro-mechanical system ("MEMS") based print head that controls the release of the fluid from the cartridge. Some cartridges for printing fluid onto a substrate include a flexible circuit to provide electrical communication between the cartridge and the dispensing device. In order to locate the substrate to be printed in close proximity with the inkjet cartridge, the electrical connections on the inkjet cartridge must be positioned away from the substrate. As a result, the electrical connections on the flexible circuit may be disposed on a different plane as an orifice where the ink is released from the inkjet cartridge. Thus, when inserting a new inkjet cartridge into the printer, the inkjet cartridge needs to be connected with the printer relative to at least two planes. This may cause limitations in the design of the printer and the access to the inkjet cartridge, as well as increase the complexity of replacing the inkjet cartridge. Moreover, some flexible circuit structures are relatively complicated to manufacture and to attach to a cartridge of a complex shape.
Further, the flexible circuit structures may be made of expensive materials such as polyimide. In addition, the flexibility of the circuit board may have poor electrical connection between the inkjet cartridge and the printer. This is due to the fact that the connection points of the flexible circuit structure may oxidize over time, especially in the presence of certain chemical vapors, causing the electrical connection between the inkjet cartridge and the printer to be diminished.
As a result, it would be beneficial to provide a microfluidic delivery system for delivering a fluid composition into the air that uses relatively inexpensive circuit boards that are also easy to manufacture. Moreover, it would be beneficial to provide a microfluidic delivery system that provides for strong and reliable electrical connection between the refill and the microfluidic delivery system. In addition, it would be beneficial to provide a microfluidic delivery system and refill that are relatively simple to replace.

Microfluidic delivery system for releasing fluid compositions


The present invention relates to an electrical machine having a permanent-magnet-excited rotor. On the perimeter of the rotor, several plate-like or lamellar permanent magnets are arranged for each rotor pole directly at the air gap adjacent to the stator of the machine. Combinations of stator-slotting harmonic fields and harmonic fields based on the division of the magnets that lead to oscillating torques. These oscillating torques are largely suppressed by having the total number of permanent magnets configured on the rotor correspond to a prime number greater than three.

The invention relates to an electrical machine having a permanent-magnet-excited rotor, and more particularly, a rotor of an electrical machine having several plate-like or lamellar permanent magnets arranged on its perimeter for each rotor pole at a point directly at the air gap adjacent to the stator of the machine.
An electrical machine having a permanent-magnet-excited rotor is described in German Patent No. U-80 18 686. Due to production engineering and cost considerations, the permanent magnets used for these types of rotors are designed as flat, rectilinear plates or strips. In the case of one rotor, if several permanent magnets are configured side-by-side on the rotor perimeter for each rotor pole, then irregularities in the magnetic field of the individual rotor poles result because of the finite gaps between the individual, adjoining magnets. These irregularities cause harmonic fields, which when combined with stator winding and stator slotting fields, can produce oscillating torques.
It would be advantageous to provide an electrical machine having a permanent-magnet-excited rotor designed to avoid oscillating torques caused by the interaction of stator and rotor harmonic fields.

Electrical machine having a permanent-magnet-excited rotor


A lever electromechanical valve actuator assembly and arrangement of electromechanical valve actuators that creates a compact actuator assembly to increase ease of serviceability, provide space for engine components and eliminate interference between the actuators and components in the vehicle engine compartment.

The present invention relates to electromechanical valves actuators and, more particularly, to compact electromechanical valve actuator assemblies and the arrangement of electromechanical valve actuators on an engine.
As engine technology advances and manufacturers strive to increase engine power, improve fuel economy, decrease emissions, and provide more control over engines, manufacturers are developing electromechanical valve actuators (also known as electromagnetic valve actuators or EMVA) to replace cam shafts for opening and closing engine valves. Electromechanical valve actuators allow selective opening and closing of the valves in response to various engine conditions.
Electromechanical valve actuators generally include two electromagnets and a spring loaded armature plate disposed between the electromagnets. The armature plate is movable between the electromagnets as the power coils are selectively energized to create a magnetic force to attract the armature plate to the energized electromagnet. The surface of the electromagnets to which the armature is attracted is generally referred to as a pole face and the armature is operationally coupled to the valve so that as the armature moves between pole faces in a pole-face-to-pole-face operation, the valve is opened and closed.
Electromechanical valve actuators are generally formed as linear electromechanical valve actuators or lever electromechanical valve actuators. One problem with linear electromechanical valve actuators is that each electromechanical valve actuator operationally coupled to the associated valve includes a relatively large set of electromagnets for opening and closing the valves (FIG. 1). The size of the electromagnets makes it difficult to position all of the linear electromechanical valve actuators over a particular cylinder, especially for engines that have four or more valves per cylinder. The size of linear electromechanical valve actuators may also limit the ease of serviceability of the engine, such as by restricting the space available for changing the spark plug. Another problem with linear electromechanical valve actuators is that linear electromechanical valve actuators generally have a substantial height extending from the cylinder head of an engine. The height of the linear electromechanical valve actuators makes them difficult to package engines in today's compact and full engine compartments. For example, linear electromechanical valve actuators may interfere with other engine parts, other components or accessories located in the engine compartment, and even the vehicle body structure, such as, the hood. Yet another problem with linear electromechanical valve actuators is that they generally draw a substantial amount of power from the vehicle electrical system, as compared with lever electromechanical valve actuators, thereby putting additional demand on the alternator in today's power hungry vehicles.
In view of the drawbacks associated with linear electromechanical valve actuators, many manufacturers have recently turned to lever electromechanical valve actuators, which due to their mechanical and magnetic properties have substantial power savings over linear electromechanical valve actuators. Lever electromechanical valve actuators also generally do not protrude as far from the cylinder head as linear electromechanical valve actuators. However, a major problem with lever electromechanical valve actuators is still the package size required on the cylinder head. Due to the set locations of valves by engine designers, designs for actuator assemblies on the engine have been traditionally limited. Most lever electromechanical valve actuators packaged on the cylinder head are arranged longitudinally in line with the cylinder head as a group, as shown in FIG. 2, with each actuator group being arranged laterally across the cylinder head. As shown in FIG. 2, the lever electromechanical valve actuators on an engine having four valves 20 per cylinder 16 requires significantly more space laterally across a cylinder head than cam shafts, thereby presenting packaging concerns in engine compartments where space is limited. Also, the arrangement of lever electromechanical valve actuators shown in FIG. 2 raises additional serviceability concerns, especially for the ease of servicing and replacing the spark plug and in some arrangements, the fuel injector. In the embodiment illustrated in FIG. 2, at least two of the actuators are completely within the perimeter of the cylinder walls extended toward the actuators, making it difficult to change the spark plug as well as service the actuators. Therefore, there is a need for additional electromechanical valve actuator arrangements that minimize package space, provide ease of serviceability, and provide room wiring assemblies and control modules communicating with the individual actuators.

Electromechanical valve actuator assembly


An electrochemical cell (10) includes first and second electrodes (12) and (14) with an electrolyte system (26) disposed therebetween. The electrolyte system includes a polymeric support structure through which is dispersed an electrolyte active species in an organic solvent. The solvent, which remains liquid to low temperatures, is a binary or higher order system comprising diethyl carbonate and one or more of propylene carbonate, ethylene carbonate, dimethyl carbonate, dipropylcarbonate, dimethylsulfoxide, acetonitrile, dimethoxyethane, tetrahydrofuran, n-methyl-2-pyrrolidone, and combinations thereof.

There has been a great deal of interest in developing better and more efficient methods for storing energy for applications such as cellular communication, satellites, portable computers, and electric vehicles to name but a few. Accordingly, there has been recent concerted efforts to develop high energy, cost effective batteries having improved performance characteristics.
Rechargeable or secondary cells are more desirable than primary (nonrechargeable) cells since the associated chemical reactions which take place at the positive and negative electrodes of the battery are reversible. Electrodes for secondary cells are capable of being recharged by the application of an electrical charge thereto. Numerous advanced electrode systems have been developed for storing electrical charge. Concurrently much effort has been dedicated to the development of electrolytes capable of enhancing the capabilities and performance of electrochemical cells.
Heretofore, electrolytes have been either liquid electrolytes as are found in conventional wet cell batteries, or solid films as are available in newer, more advanced battery systems. Each of these systems have inherent limitations and related deficiencies which make them unsuitable for various applications. Liquid electrolytes, while demonstrating acceptable ionic conductivity tend to leak out of the cells into which they are sealed. While better manufacturing techniques have lessened the occurrence of leakage, cells still do leak potentially dangerous liquid electrolytes from time to time. Moreover, any leakage in the cell lessens the amount of electrolyte available in the cell, thus reducing the effectiveness of the device.
Solid electrolytes are free from problems of leakage, however, they have traditionally offered inferior properties as compared to liquid electrolytes. This is due to the fact that ionic conductivities for solid electrolytes are often one to two orders of magnitude poorer than a liquid electrolyte. Good ionic conductivity is necessary to insure a battery system capable of delivering usable amounts of power for a given application. Most solid electrolytes have not heretofore been adequate for many high performance battery systems.
One class of solid electrolytes, specifically gel electrolytes, have shown great promise for high performance battery systems. Gel electrolytes contain a significant fraction of solvents and/or plasticizers in addition to the salt and polymer of the electrolyte itself. Traditionally, a single solvent has been used, into which is incorporated the electrolyte salt which provides the ion transport between the opposing electrodes. More recently, researchers have begun to experiment with mixed solvent systems in an effort to enhance device performance. While these efforts have met with some success, one area in which performance has not been addressed is low temperature performance. As temperature drops below freezing (i.e., 0.degree. C.), lithium battery device capacity rapidly drops from about 60% to virtually 0% by -20.degree. C. This is a serious limitation to lithium battery performance as the applications devices into which the cells are incorporated--namely cellular phones, two-way radios, and laptop computers--are often in such low temperature environments.
Accordingly, there exists a need for a new electrolyte system which combines the properties of high ionic conductivity and excellent low temperature performance. The electrolytes should not compromise performance at higher temperatures, should also be relatively cost effective, and easy to produce.

Electrolyte composition for rechargeable electrochemical cells


A noise cancelling device includes an extracting unit configured to extract a first noise from a signal, the signal being based on an input audio signal, a storing unit configured to store noise characteristic information on a second noise, the second noise remaining after subtracting the extracted first noise from the signal based on the audio signal. And the device further includes a cancelling unit configured to perform cancelling processing for cancelling a noise on the input audio signal based on the first noise and the noise characteristic information on the second noise.

1. Technical Field
The present disclosure relates to a noise cancelling device.
2. Related Art
Conventional noise cancelling devices subtract operation noise which is produced as a result of an operation of driving a zoom lens and the like from obtained original audio data to provide audio data of clearer sound in sound recording or video recording.
For example, a noise cancelling device as disclosed in JP 2006-211436 A is known.
Recently, as digital cameras have been downsized, the source of the operation noise, such as a zoom lens, and a microphone for collecting ambient sounds for obtaining audio signals have been getting nearer to each other. On the other hand, digital cameras capable of capturing not only a still picture but also a motion picture by multiplying and recording the audio signals have been more widely used. Under such a circumstance, operation noise needs to be addressed more than ever.

Panasonic Intellectual Property Management Co., Ltd.


An improved throat plate is disclosed herein. The throat plate includes a main body, an opening in the main body for allowing a cutting tool to extend therethrough, and a retainer assembly attached to the main body for retaining the throat plate in contact with the table. Preferably the retainer assembly is pivotally attached to the main body and/or is movable between a first position contacting the table and a second position bypassing the table. The retaining assembly may pivot about an axis substantially perpendicular to a plane of the table. The retainer assembly may also include an extension that contacts underside of the table. The extension in turn may include a camming surface contacting the underside of the table.

FIG. 1 shows a power tool 10 incorporating a prior art throat plate 11 on table 13. The power tool shown in FIG. 1 is a table saw, but persons skilled in the art should recognize that the invention is applicable to any tool having a cutting tool through a table, at least momentarily. Similarly, the cutting tool 12 shown in FIG. 1 is a circular blade, but persons skilled in the art will recognize that the invention is equally applicable to any other cutting tools, such as drill bits, grinder wheels, sanding wheels, linear edge blade including, but not limited to, scroll saw blades, band saw blades, jigsaw blades, hole saw blades, etc. Preferably the cutting tool 12 is driven by a motor (not shown).
Throat plate 11 is typically fixedly attached to table 13 by screws 14. However, operators may want to change the throat plate 11 to accommodate wider cutting tools 12. Accordingly, it is preferable to provide a throat plate that is easy to install and/or remove.