A working label switched path (LSP) between neighbor label switched routers (LSRs) in a ring network that utilizes label switching is protected by an LSP that connects the neighbor LSRs of the working LSP in an opposite direction to the working LSP. If the working LSP fails, then packets are switched to the protection LSP. Switched packets traverse the protection LSP until they reach the neighbor LSR that they would have reached had the packets traversed the working LSP. Time-to-live (TTL) values of packets that traverse the protection LSP are adjusted to account for the number of hops on the protection LSP so that the TTL values of the packets are the same after traversing the protection LSP as they would have been had they traversed the working LSP. After traversing the protection LSP packets can be switched back to the working LSP or switched to a next hop LSP.

In packet-switched networks, packets traveling from a source address to a destination address may be transmitted through many intermediate network nodes, such as switches or routers. Intermediate network nodes that receive packets headed for the destination address utilize look-up tables to determine the next hop for the packets. Label switching is a technique that has been developed to expedite the look-up process at each hop as packets travel from a source address to a destination address. In brief, label switching involves attaching a label to a packet that enables the next hop of the packet to be quickly determined by an intermediate network node that has received the packet. One label switching protocol that is being standardized by the Internet Engineering Task Force (IETF) is known as multi-protocol label switching (MPLS).
FIG. 1 depicts multiple network nodes 102 that utilize MPLS to forward packets through a mesh network. The network nodes are referred to as label switch routers (LSRs) and a group of interconnected LSRs define an MPLS domain 104. LSRs that are at the edge of the MPLS domain and provide an interface to non-MPLS network nodes are referred to as edge LSRs (also as ingress LSRs and egress LSRs with respect to packets that are entering or leaving the MPLS domain). The path that labeled packets travel through an MPLS domain is referred to as the label switch path (LSP). FIG. 1 depicts examples of two LSPs, working LSP 1 and protection LSP 1, which extend between LSRs in the MPLS domain. Although only two LSPs are depicted, an MPLS domain may include thousands of unique LSPs.
MPLS is often used in conjunction with the Internet protocol (IP) at the Network layer (layer 3) and a Data Link layer (layer 2) protocol such as Ethernet (IEEE 802.3x), asynchronous transfer mode (ATM), or Frame Relay. According to the MPLS protocol, an MPLS header, also referred to as a "shim header," is inserted between the Network layer header (the inner header) and the Data Link layer header (the outer header) to guide a labeled packet through an MPLS domain. Multiple shim headers can be stacked, as is known in the field, to support hierarchical operations. MPLS can also be used in a layer 2 environment where the shim header is located between two layer 2 headers.
FIG. 2 depicts an example of a labeled packet that includes an outer header 208 (i.e., a MAC header that includes a destination address, a source address, and a type field), a label switching header 210 (also referred to as the shim header), an inner header 212 and payload 214 (i.e., an IP header and an IP payload), and a MAC trailer 216 (i.e., the CRC). As described by the IETF (RFC 3032, January 2001) and shown in the expanded view of FIG. 2, an MPLS shim header includes a 20-bit MPLS label field 218, a 3-bit experimental use field 220, a 1-bit stacking field 222, and an 8-bit time-to-live (TTL) field 224. The MPLS label field carries the label value that is used to forward a packet to the next LSR. The experimental use field is not yet fully defined, the stacking field is used to identify when an MPLS header is the last MPLS header in a stack of MPLS headers, and the TTL field carries a TTL value that places a limit on the number of hops an MPLS packet can traverse within an MPLS domain.
As is well known in the field, packet-switched networks are currently being adapted to support traditional telecommunications traffic, such as voice communications. In order for packet-switched networks to support traditional telecommunications traffic, the packet-switched networks must include failure protection mechanisms that ensure a standard of reliability that meets or exceeds the reliability standards that are achieved by circuit-switched networks. For example, it is important that a label switched network can recover from an LSP failure within 50 milliseconds (ms).
In metropolitan areas, traditional circuit-switched traffic is often carried using ring network architectures. Ring networks are now being adapted to carry packet-switched traffic and label switching is being implemented on the ring networks to provide improved quality of service. In order for packet-switched ring networks to carry telecommunications traffic, they must ensure a standard of reliability that meets or exceeds the reliability standards of circuit-switched ring networks.
One failure protection technique that has been proposed for mesh-type MPLS-based networks involves establishing a unique protection LSP for each working LSP and switching packets from the working LSP to the protection LSP if the working LSP fails. For example, referring to the mesh network of FIG. 1, protection LSP 1 is established to provide a protection pathway for working LSP 1. If there is a failure of a link that is utilized by the working LSP, then packets that would have been sent on the working LSP are switched to the protection LSP. The TTL values of the packets that are switched to the protection LSP are set to allow the packets to traverse the number of hops on the protection LSP. After the switched packets have traversed all of the hops on the protection LSP, the shim headers are popped.
In the example of FIG. 1, if there is a failure of either one of the links that supports working LSP 1, then, according to the technique, packets that would have been sent on working LSP 1 are switched to protection LSP 1 and the TTL values are set to allow the packets to traverse the protection LSP. The switched packets traverse the protection LSP until the destination LSR is reached and then the protection LSP shim header is popped, causing the packets to exit the MPLS domain. While this technique works well in a mesh-type network, the technique does not work as well in a ring-type network because label switched packets may traverse multiple different LSPs around a ring before exiting the MPLS domain.
Another drawback to the above-described protection scheme is that packets traversing the protection LSP will arrive at the destination LSR on a different port than the port used by the working LSP. Having packets that previously arrived on one port suddenly arrive on a different port indicates to the receiving LSR that there has been a network topology change that must be learned. Topology learning consumes valuable processing time that could be used to perform other critical operations.
In view of the desire to use ring-type packet-switched networks to carry traditional telecommunications traffic and the problems of current failure protection techniques, what is needed is a failure protection technique for label switched ring networks that provides fast protection switching, that does not trigger additional topology learning, and that is easy to implement.

Method and system for providing failure protection in a ring network that utilizes label switching


An alpha-numeric display arrangement, designed to be vandal-proof, has an opaque mould plate mounted on the reverse of a metal front plate. Elongate apertures in the front plate each form one of a plurality of segments of the alpha-numeric display. Elongate apertures in the mould plate are each accurately aligned with a respective one of the apertures in the front plate. Molten transparent material is introduced to a required level in each of the contiguous aperture pairs. A space is left above the solidified material in which a light emitting diode mounted on a lighting board is received. Thus, each of the apertures is provided with a light emitting diode which is in optical communication with the transparent material provided within each of the apertures.

The present invention relates to a light display arrangement and a method of forming the same.
Display arrangements for providing illuminated displays find wide use in a variety of situations. Particular forms of light display arrangements comprise alpha-numeric light displays which are intended to provide for an illuminated figure such as a numeral or letter, or a combination thereof, so as to relay information to persons located in the vicinity of the display.
Typical examples comprise the light displays associated with a light system and which, for those waiting for a lift to arrive at their particular floor level, can provide for a clear indication of the location of the lift in the building at any particular time.
Whether used as part of a lift system or otherwise, light displays are commonly provided at locations readily accessible by members of the public and often without supervision. This has the potential disadvantage that such light displays can comprise readily accessible targets for those intent on vandalism or other potentially destructive activities.
While attempts have been made to provide for so-called vandal-proof light displays, such known displays are found to exhibit limitations and disadvantages. For example, although the information being conveyed by way of the display can be readily identified when the display is viewed head on, the displayed information appears far from clear when the display is viewed from the side thereof. Such disadvantages are particularly exhibited when the display comprises a segmented alpha-numeric display in which the illumination of each of the segments has to be individually controlled so as to provide for the selective display of a required range of numerals and/or letters.

Light display and method of forming the same


A comestible product press comprising a first handle having first and second ends; a second handle having first and second ends, wherein the first and second handles are hingedly connected to one another at their first ends; a first protrusion on the first handle, the first protrusion extending toward the second handle when the first and second handles are positioned to define an acute angle therebetween; a second protrusion on the second handle, the second protrusion extending away from the first handle when the first and second handles are positioned to define an acute angle therebetween; and an intermediate member connected to at least one of the first and second handles, wherein the intermediate member substantially fills the space between the first and second protrusions when the first and second handles are brought together.

A number of different comestible product presses exist, such as presses for lemons, limes, garlic, and other foods. Many of such presses are manually operated, and can include one or more handles enabling a user to exert pressure upon a comestible product. Among other things, such pressure can be exerted to extract fluid from the comestible product (e.g., press juice from lemons, limes, or other fruits), to extract any other part of the comestible product (e.g., remove pits or seeds from a food item), and/or to crush, crack, shape, or change the comestible product in any number of different manners.
Although many advancements have already been made in comestible product presses, still others are possible, and offer advantages over conventional comestible product presses


A method for diagnosis of a defect of an object to be inspected, such as a rotational machine, etc., by measuring a vibration generated thereby, wherein a measured signal generated by the object is detected, an amplitude probability density function of wave-form of the obtained measured signal is expanded orthogonally through a Gram-Charlier series, and the Gram-Charlier series are calculated so as to make diagnosis of defect(s) in the object to be inspected.

The present invention relates to a defect diagnosis in a friction system, such as bearings and/or gears in a rotational machine, and to a defect diagnosis in a construction system, such as an unbalance in rotating masses and/or a misalignment where two rotational machines run off an axis thereof.
A sudden and/or unexpected stoppage of manufacturing machinery equipment brings about extremely large economic loss. In facilities utilizing the manufacturing equipment, precautionary maintenance is practiced for preventing such trouble such as a sudden unexpected stoppage. As an example of the method of precautionary maintenance for preventing such trouble, a sound or/and a vibration being generated by the machinery equipment in operation is measured so as to determine the condition thereof. Such a procedure is called a xe2x80x9cstate-base precautionxe2x80x9d. Here, the conventional arts will be explained in terms of the state-base precaution, by taking a vibration measurement as an example.
When making the diagnosis of the presence of troubles by measuring the vibration of machinery equipment, it is decided whether the measured vibration exceeds a reference value or not in the magnitude thereof. Ordinarily, two kinds of reference values are prepared for the decisions. Namely, if the detected value exceeds the reference value being the smaller of the reference values, it is found to be in a domain of caution, therefore observation must be performed frequently, though the equipment operation will be continued. If the detected value exceeds the reference value being the larger of the reference values, it is found to be in a domain of danger, therefore equipment operation must be stopped in order for the equipment to be restored or repaired immediately. When the state of the machinery equipment reaches to the caution domain, a time when it reaches to the danger domain is predicted from a guide such as a chart or a graph indicating a tendency in the past of changes from a normal state into the caution domain, so as to provide for production planning which has the highest economic efficiency and a planning of maintenance, including the restoration or repair.
The equipment of the manufacturing machines located in a factory or works of a company varies depending upon the purposes thereof, i.e., there are used various kinds or sorts of machinery, being different in revolution speed, electric power consumption (torque), and/or loads, including large or small values thereof, or a machine having a large vibration or one having a small vibration.
Each reference value for deciding the presence of the defect or failure is unique and characteristic to each particular machinery equipment, and the reference values are decided on the basis of a large accumulated number of sample data representative of the defect or failure conditions, as well as those representative of the normal conditions. However, for fully obtaining the effect of the state-base precaution, an appropriate reference value for decision is needed.
A significant investment of labor is needed to determine the above reference for decision, since enough sample data may not be obtainable due to a rareness or scarcity of the troubles or accident, or since the kinds or sorts of the machines to be inspected is too large in number. Further, there are many companies which cannot apply the state-base maintenance, because of such reasons as that there is no engineer for maintenance work who has applied knowledge in trouble or defect diagnosis, therefore the sample data cannot be gathered.
Though the state-base maintenance is an economical and superior method of maintenance with reduced costs or expenses, the most suitable possible decision reference or criterion must be decided upon so as to apply the state-base maintenance, as mentioned previously. Many companies are unable to apply the state-base maintenance, since this reference for decision cannot be appropriately decided thereby.
According to the present invention, an object is to provide a diagnosis method wherein attention is paid to a difference of a probability density function of amplitude obtained by normalizing a wave-form of a measured signal, such as the wave-form of vibration which is generated by the machine, from a normal distribution, thereby proposing the decision criterion which can be applied in common to the different facilities of many rotational machines, and also to provide a trouble or defect diagnosis apparatus comprising those functions.
The present invention is based upon a principle that the amplitude probability density function of a measured signal, such as the vibration being generated by an object to be detected, for example, a machine, etc., operating under a normal condition, coincides with the normal distribution, however, it is shifted from the normal distribution when trouble or abnormal condition arises in the machine.
According to the present invention, while no component information relating to the measured signal is utilized, such as the amplitude and the vibration number thereof which is generated by the object such as a machine to be inspected, the normalized amplitude probability density function is decided to coincide with the normal distribution or not, fully independent of specifications such as the revolution number, the electric power consumption, the load and the scale of the structure of the machine.
Namely, according to the present invention, there is provided a defect diagnosis method for an object to be inspected, comprising:
detecting a measured signal being generated by said object to be inspected;
expanding orthogonally an amplitude probability density function of a wave-form of the obtained measured signal in a Gram-Charlier series; and
calculating the Gram-Charlier series so as to make a diagnosis of a defect in the object to be inspected.
Here, the defect in the present invention means indicates the condition where the machine operates differently from operation under the normal condition, but not that it is already in an inoperable condition.
Further, according to the present invention, there is provided a defect diagnosis method for an object to be inspected, comprising:
detecting a measured signal being generated by said object to be inspected;
expanding orthogonally an amplitude probability density function of a wave-form of the obtained measured signal in a Gram-Charlier series; and
Further, according to the present invention, there is provided a defect diagnosis method for an object to be inspected, comprising:
detecting a measured signal being generated by said object to be inspected;
expanding a wave-form of the obtained measured signal obtained in a Fourier series to obtain a frequency spectrum;
expanding orthogonally an amplitude probability density function by viewing the obtained frequency spectrum from an axis of an amplitude thereof in a Gram-Charlier series; and
calculating the Gram-Charlier series so as to make diagnosis of a defect in said object to be inspected.
Further, according to the present invention, there is provided a defect diagnosis method for an object to be inspected, comprising:
detecting a measured signal being generated by said object to be inspected;
expanding a wave-form of the obtained measured signal in a Fourier series to obtain a frequency spectrum;
expanding orthogonally an amplitude probability density function by viewing the obtained frequency spectrum from an axis of an amplitude thereof in a Gram-Charlier series; and
calculating a difference from a normal distribution so as to make a diagnosis of a defect in the object to be inspected. In the invention defined in the above, the measured signal may be a vibration.
In the invention defined in the above, the measured signal may be an acoustic, an acoustic emission, fluctuations of current or of effective electric power rather than a vibration.
In the invention defined in the above, the object to be inspected can include a vehicle, an aircraft and a construction other than an ordinary machine.
Furthermore, according to the present invention, there is provided a defect diagnosis apparatus for implementing the defect diagnosis method, comprising a probe with respect to the object to be inspected.
Here, a method with use of an expanding equation of the Gram-Charlier series will be explained in detail below.
The amplitude probability density function of the normal distribution N(xcexc,"sgr"2) can be expressed as follows, assuming that an averaged value is xcexc and a dispersion is "sgr"2.       f              (      x      )        =            1              σ                                      2                        π                                          ⅇ              -                                            (                              x                -                μ                            )                        2                                2                                      σ              2
Here, by making the averaged value xcexc=0 and the dispersion "sgr"2=1, the normalized N(0,1) can be expressed as follows:       f              (      x      )        =            1                        2                    π                                ⅇ              -                              x            2                    2
where, xcfx86(x) is as follows.       ϕ              (      x      )        =      ⅇ          -                        x          2                2
It is presumed that an arbitrary density function p(x) can be expanded in the following form with use of a normal distribution density function xcfx86(x) and a derived function thereof:                               p                                (            x            )                          =                                            c              0                                                                  ϕ                                  (                  0                  )                                                                          (                x                )                                              +                                                    c                1                                            1                !                                                                                ϕ                                  (                  1                  )                                                                          (                x                )                                              +                                                    c                2                                            2                !                                                                                ϕ                                  (                  2                  )                                                                          (                x                )                                              +                                                    c                3                                            3                !                                                                                ϕ                                  (                  3                  )                                                                          (                x                )                                              +                                                    c                4                                            4                !                                                                                ϕ                                  (                  4                  )                                                                          (                x                )                                              +          …                                    (        1        )
where the xcfx86(n)(x) is expressed by a polynomial of Hermite as below.
xcfx86(n)(x)=(xe2x88x921)nHn(x)xcfx86(x)xe2x80x83xe2x80x83(2)
And the equation (1) is derived as follows.                               p                                (            x            )                          =                                            c              0                                                                  H                0                                                          (                x                )                                                                ϕ                                            (                x                )                                              -                                                    c                1                                            1                !                                                                                H                1                                                          (                x                )                                                                ϕ                                            (                x                )                                              +                                                    c                2                                            2                !                                                                                H                2                                                          (                x                )                                                                ϕ                                            (                x                )                                              -                                                    c                3                                            3                !                                                                                H                3                                                          (                x                )                                                                ϕ                                            (                x                )                                              +                                                    c                4                                            4                !                                                                                H                4                                                          (                x                )                                                                ϕ                                            (                x                )                                              -          …          +                                                    c                n                                            n                !                                                                                H                n                                                          (                x                )                                                                ϕ                                            (                x                )                                              -          …                                    (        3        )
Then, by differentiating the normal distribution density function xcfx86(x), the following xcfx86(n)(x) is obtained:
xcfx86(1)("khgr")=xe2x88x92xexe2x88x92x22=xe2x88x92xxc2x7xcfx86(x)
xcfx86(2)(x)=xe2x88x92xcfx86(x)xe2x88x92xxc2x7xcfx86(1)(x)=xe2x88x92xcfx86(x)+x2xc2x7xcfx86(x)=(x2xe2x88x921)xc2x7xcfx86(x)
xe2x80x83xcfx86(3)(x)=2xxc2x7xcfx86(x)+(x2xe2x88x921)xc2x7xcfx86(1)(x)=2xxc2x7xcfx86(x)xe2x88x92(x2xe2x88x921)xc2x7xxc2x7xcfx86(x)=xe2x88x92(x3xe2x88x923x)xc2x7xcfx86(x)
xcfx86(4)(x)=(xe2x88x923x2+3)xc2x7xcfx86(x)xe2x88x92(x3xe2x88x923x)xc2x7xcfx86(1)(x)=(xe2x88x923x2+3)xc2x7xcfx86(x)+(x3xe2x88x923x)xc2x7xxc2x7xcfx86(x)=(x4xe2x88x926x2+3)xc2x7xcfx86(x)
xcfx86(5)(x)=(4x3xe2x88x9212x)xc2x7xcfx86(x)+(x4xe2x88x926x2+3)xc2x7xcfx86(1)(x)=(4x3xe2x88x9212x)xc2x7xcfx86(x)xe2x88x92(x4xe2x88x926x2+3)xc2x7xxc2x7xcfx86(x)=xe2x88x92(x5xe2x88x9210x3+15x)xc2x7xcfx86(x)
xcfx86(6)(x)=(xe2x88x925x4+30x2xe2x88x9215)xc2x7xcfx86(x)xe2x88x92
(x5xe2x88x9210x3+15x)xc2x7xcfx86(1)(x)=
(xe2x88x925x4+30x2xe2x88x9215)xc2x7xcfx86(x)+
(x5xe2x88x9210x315x)xc2x7xxc2x7xcfx86(x)=
(x6xe2x88x9215x4+45x2xe2x88x9215)xc2x7xcfx86(x)
From those differentiating values and the above equation (2), the following can be obtained:
H0(x)=1
H1(x)=x
H2(x)=x2xe2x88x921
H3(x)=x3xe2x88x923x
H4(x)=x4xe2x88x926x2+3
H5(x)=x5xe2x88x9210x3+15x
H6(x)=x6xe2x88x9215x4+45x2xe2x88x9215
Further, the polynomial of Hermite has an orthogonality as below:                                           ∫                          -              ∞                        ∞                                                                        H                m                                                          (                x                )                                                                                H                n                                                          (                x                )                                                                ϕ                                            (                x                )                                                    =                                            δ              mn                                                  (              x              )                                =                      xe2x80x83                                                        m              !                                                  xe2x80x83                                                  (                              m                =                n                            )                                                              =                  xe2x80x83                                  0                                xe2x80x83                                          (                          m              ≠              n                        )
An integration is executed by multiplying Hn(x) at the both sides of the equation (3):             ∫              -        ∞            ∞                                    H          n                                  (          x          )                                  p                          (          x          )                                  ⅆ        x              =                    c        0                                    ∫                      -            ∞                    ∞                                                            H              n                                                  (              x              )                                                                    H              0                                                  (              x              )                                                      ϕ                                      (              x              )                                            -                            c          1                          1          !                                            ∫                      -            ∞                    ∞                                                            H              n                                                  (              x              )                                                                    H              1                                                  (              x              )                                                      ϕ                                      (              x              )                                            +                            c          2                          2          !                                            ∫                      -            ∞                    ∞                                                            H              n                                                  (              x              )                                                                    H              2                                                  (              x              )                                                      ϕ                                      (              x              )                                            -                            c          3                          3          !                                            ∫                      -            ∞                    ∞                                                            H              n                                                  (              x              )                                                                    H              3                                                  (              x              )                                                      ϕ                                      (              x              )                                            +                            c          4                          4          !                                            ∫                      -            ∞                    ∞                                                            H              n                                                  (              x              )                                                                    H              4                                                  (              x              )                                                      ϕ                                      (              x              )                                            -    …    +                            c          n                          n          !                                            ∫                      -            ∞                    ∞                                                            H              n                                                  (              x              )                                                                    H              n                                                  (              x              )                                                      ϕ                                      (              x              )                                            -    …
Since the Hermite polynomial has the orthogonality, only the clauses having the same order, and derived is the following:                                                                         (                                  -                  1                                )                            n                                                                  ∫                                  -                  ∞                                ∞                                                                                H                    n                                                                          (                    x                    )                                                                                p                                                        (                    x                    )                                                                                ⅆ                  x                                                              =                      c            n
                                                                                c                  0                                =                                  xe2x80x83                                                                                ∫                                          -                      ∞                                        ∞                                                                                p                                                                    (                        x                        )                                                                                ⅆ                      x                                                                                c                  1                                =                                  xe2x80x83                                                                  -                                                            ∫                                              -                        ∞                                            ∞                                                                                x                        ·                                                  p                                                                                (                            x                            )                                                                                ⅆ                        x                                                                                c                  2                                =                                  xe2x80x83                                                                                ∫                                              -                        ∞                                            ∞                                                                                (                                                                              x                            2                                                    -                          1                                                )                                                                                p                                                                          (                          x                          )                                                                                ⅆ                        x                                                                              =                                                                                ∫                                                  -                          ∞                                                ∞                                                                                x                          2                                                                                p                                                                                (                            x                            )                                                                                ⅆ                          x                                                                                -                                                                  ∫                                                  -                          ∞                                                ∞                                                                                p                                                                                (                            x                            )                                                                                ⅆ                          x                                                                                c                  3                                =                                  xe2x80x83                                                                                -                                                                  ∫                                                  -                          ∞                                                ∞                                                                                (                                                                                x                              3                                                        -                                                          3                                                            x                                                                                )                                                                                p                                                                                (                            x                            )                                                                                ⅆ                          x                                                                                =                                                            -                                                                        ∫                                                      -                            ∞                                                    ∞                                                                                x                            3                                                                                p                                                                                (                              x                              )                                                                                ⅆ                            x                                                                                +                                          3                                                                                ∫                                                      -                            ∞                                                    ∞                                                                                x                            ·                                                          p                                                                                (                                x                                )                                                                                ⅆ                            x                                                                                c                    4                                    =                                      xe2x80x83                                                                                ∫                                                  -                          ∞                                                ∞                                                                                (                                                                                x                              4                                                        -                                                          6                                                                                x                                2                                                                                +                            3                                                    )                                                                                p                                                                                (                            x                            )                                                                                ⅆ                          x                                                                                =                                                                                ∫                                                      -                            ∞                                                    ∞                                                                                x                            4                                                                                p                                                                                (                              x                              )                                                                                ⅆ                            x                                                                                -                                              6                                                                                ∫                                                          -                              ∞                                                        ∞                                                                                x                              2                                                                                p                                                                                (                                x                                )                                                                                ⅆ                              x                                                                                +                                                                                xe2x80x83                                                                                xe2x80x83                                                                  3                                                                              ∫                                              -                        ∞                                            ∞                                                                                p                                                                          (                          x                          )                                                                                ⅆ                        x                                                                                c                  5                                =                                  xe2x80x83                                                                                -                                                                  ∫                                                  -                          ∞                                                ∞                                                                                (                                                                                x                              5                                                        -                                                          10                                                                                x                                3                                                                                +                                                          15                                                            x                                                                                )                                                                                p                                                                                (                            x                            )                                                                                ⅆ                          x                                                                                =                                                            -                                                                        ∫                                                      -                            ∞                                                    ∞                                                                                x                            5                                                                                p                                                                                (                              x                              )                                                                                ⅆ                            x                                                                                +                                                                                xe2x80x83                                                                                10                                                                                ∫                                                  -                          ∞                                                ∞                                                                                x                          3                                                                                p                                                                                (                            x                            )                                                                                ⅆ                          x                                                                                -                                      15                                                                                ∫                                                  -                          ∞                                                ∞                                                                                x                          ·                                                      p                                                                                (                              x                              )                                                                                ⅆ                          x                                                                                c                  6                                =                                  xe2x80x83                                                                                ∫                                          -                      ∞                                        ∞                                                                                (                                                                        x                          6                                                -                                                  15                                                                                x                            4                                                                          +                                                  45                                                                                x                            2                                                                          -                        15                                            )                                                                                p                                                                    (                        x                        )                                                                                ⅆ                      x                                                                                =                                  xe2x80x83                                                                                ∫                                              -                        ∞                                            ∞                                                                                x                        6                                                                                p                                                                          (                          x                          )                                                                                ⅆ                        x                                                                              -                                      15                                                                                ∫                                                  -                          ∞                                                ∞                                                                                x                          4                                                                                p                                                                                (                            x                            )                                                                                ⅆ                          x                                                                                +                                      45                                                                                ∫                                                  -                          ∞                                                ∞                                                                                x                          2                                                                                p                                                                                (                            x                            )                                                                                ⅆ                          x                                                                                -                                                                                xe2x80x83                                                                  15                                                                              ∫                                              -                        ∞                                            ∞                                                                                p                                                                          (                          x                          )                                                                                ⅆ                        x                                                                                (        4        )
Here, it is assumed that n number of time series data xcexi are collected from the vibration data which the machine generates.
Then, the average value xcexc is obtained as follows, and the total data is shifted by the average value (xcexi=xcexixe2x88x92xcexc).   μ  =                    ∑                  i          =          1                n                          λ        i              n
Next, an effective value "sgr" is obtained as is expressed below, so as to normalize the total data (xcexi=xcexi/"sgr").   σ  =                              ∑                      i            =            1                    n                                  λ          i          2                    n
The following summations are obtained from the time series data which are normalized:             s      0        =    n    ,      xe2x80x83                s      1        =                  ∑                  i          =          1                n                          λ        i              ,      xe2x80x83                s      2        =                  ∑                  i          =          1                n                          λ        i        2              ,      xe2x80x83                s      3        =                  ∑                  i          =          1                n                          λ        i        3              ,
                s      4        =                  ∑                  i          =          1                n                          λ        i        4              ,      xe2x80x83                s      5        =                  ∑                  i          =          1                n                          λ        i        5              ,      xe2x80x83                s      6        =                  ∑                  i          =          1                n                          λ        i        6              ,  …
Then, those summations are divided by the number of the data as follows:                     s        0            =                        n          /          n                =        1              ,          xe2x80x83                          s        1            =                                                  ∑                              i                =                1                            n                                                  λ              i                                n                =        0              ,          xe2x80x83                          s        2            =                                                  ∑                              i                =                1                            n                                                  λ              i              2                                n                =        1              ,          xe2x80x83                          s        3            =                                    ∑                          i              =              1                        n                                          λ            i            3                          n                                s        4            =                                    ∑                          i              =              1                        n                                          λ            i            4                          n              ,          xe2x80x83                          s        5            =                                    ∑                          i              =              1                        n                                          λ            i            5                          n              ,          xe2x80x83                          s        6            =                                    ∑                          i              =              1                        n                                          λ            i            6                          n              ,    …
By inserting them into those coefficient cj, then the following is obtained:
c0=s0=1
c1=xe2x88x92s1=0
c2=s2xe2x88x92s0=0
c3=xe2x88x92s3+3s1=xe2x88x92s3
c4=s4xe2x88x926s2+3s0=s4xe2x88x923
c5=xe2x88x92s5+10s3xe2x88x9215s1=xe2x88x92s5+10s3
c6=s6xe2x88x9215s4+45s2xe2x88x9215s0=s6xe2x88x9215s4+30
By the normalization as in the above, c0=1 and c1=c2=0, therefore a compensated clause starts with the third clause.
The coefficient cj can be expressed as below.
c3=xe2x88x92s3
c4=s4xe2x88x923
c5=xe2x88x92s5+10s3
c6=s6xe2x88x9215s4+30
The series being obtained by the expansion in this manner is called the Gram-Charlier series. The Gram-Charlier series contain therein elements of the defect or trouble and deterioration. However, mathematically, as the Gram-Charlier series are in orthogonal relationships with each other, the elements of the defects and deterioration contained therein can be considered to be totally independent of each other.
When the amplitude probability density function is the normal distribution, all of the Gram-Charlier series become zero. When the condition comes into the defect or trouble and shifts from the normal distribution, each absolute value of these numeral (series) values becomes large. Accordingly, by determining the criterion or reference value of the Gram-Charlier series, it is possible to make diagnosis of the defects or troubles.
From the equation (3), the arbitrary density function p(x) becomes as follows:                               p                                (            x            )                          =                              (                          1              +                                                                    c                    3                                                        3                    !                                                                                (                                                            x                      3                                        -                                          3                                            x                                                        )                                            +                                                                    c                    4                                                        4                    !                                                                                (                                                            x                      4                                        -                                          6                                                                    x                        2                                                              +                    3                                    )                                            +                                                                    c                    5                                                        5                    !                                                                                (                                                            x                      5                                        -                                          10                                                                    x                        3                                                              +                                          15                                            x                                                        )                                            +                                                                    c                    6                                                        6                    !                                                                                (                                                            x                      6                                        -                                          15                                                                    x                        4                                                              +                                          45                                                                    x                        2                                                              -                    15                                    )                                            +              …                                                  xe2x80x83                        }                                          ϕ                                      (              x              )                                                          (        5        )
This is called a Gram-Charlier distribution function. This Gram-Charlier distribution function is the function which is the most analogous or approximated to the amplitude probability density function which is actually measured.
The arbitrary density function can be expressed by a sum of the normal distribution density function xcfx86(x) and a differentiation function r(x), as shown in the following equation:
p(x)=xcfx86(x)+r(x)
where the difference function r(x) becomes as below from the equation (5):                               r                                (            x            )                          =                                            p                                            (                x                )                                      -                          ϕ                                            (                x                )                                              =                                    (                                                                                c                      3                                                              3                      !                                                                                (                                                                  x                        3                                            -                                              3                                                x                                                              )                                                  +                                                                            c                      4                                                              4                      !                                                                                (                                                                  x                        4                                            -                                              6                                                                          x                          2                                                                    +                      3                                        )                                                  +                                                                            c                      5                                                              5                      !                                                                                (                                                                  x                        5                                            -                                              10                                                                          x                          3                                                                    +                                              15                                                x                                                              )                                                  +                                                                            c                      6                                                              6                      !                                                                                (                                                                  x                        6                                            -                                              15                                                                          x                          4                                                                    +                                              45                                                                          x                          2                                                                    -                      15                                        )                                                  +                …                                                          xe2x80x83                            )                                                  ϕ                                            (                x                )                                                                        (        6        )
Then, the next equation is defined:                     δ        =                              ∫                          -              6                        6                                                                        (                                  r                                                        (                    x                    )                                                  )                            2                                                  ⅆ              x                                                          (        7        )
where a square integration value of the difference function r(x) from 6 to xe2x88x926 is the difference xcex4.
The difference xcex4 is zero when the amplitude probability density function is coincident with the normal distribution, while the numeral value comes to be large when being in the condition of the defect or trouble and shifted from the normal distribution. Accordingly, by determining the criterion or the reference value of the difference xcex4, it is possible to make the diagnosis of the defect or trouble.

Defect diagnosis method and defect diagnosis apparatus


A compiler includes a front-end module, an optimization module, and a back-end module. The front-end module pre-processes a source code to generate an intermediate code. The optimization module optimizes the intermediate code. The back-end module translates the optimized intermediate code to generate a machine code. Optimization includes translating a branch instruction in the intermediate code into performing the following operations: establishing a post dominator tree for the branch instruction to find an immediate post dominator of the branch instruction as a reconverge point of a first path and a second path of the branch instruction; inserting a specific instruction at the front end of the reconverge point, so as to jumping to execute the instructions of the second path on the condition that once the specific instruction on the first path is executed.

In recent years, with the rise of Internet of things (IOT) and the rapid development of artificial intelligence, machine learning and other fields, the amount of data processing has increased significantly. The traditional cloud computing has been unable to cope with such a large amount of real-time data processing, and thus has been replaced by the application architecture of distributed computing (e.g., fog computing, edge computing, end user computing). For example, edge computing moves computations of applications, data, and services from the central node of the network to the logical edge node of the network for processing. In other words, edge computing decomposes the large-scale services that were originally processed by the central node into small and many manageable parts, and distributes them to the edge nodes for processing. The edge node is close to the user terminal device, thus speeding up the data processing and transmission and reducing the delay.
Therefore, a general-purpose graphics processing unit (GPGPU) has been widely used in such applications that need to compute a large amount of data and can be highly parallelized. In addition to processing graphics data, such graphics processing unit can also be used to calculate the general computing tasks that were originally processed by a CPU, and was generally not associated with graphics processing. Due to the powerful parallel processing capability and programmable pipelines of the modern graphics processing unit, the performance of the GPGPU can greatly surpass that of the traditional CPU, for processing single instruction multiple data (SIMD) on the condition that the computation of data processing is much larger than that of data scheduling and transmission.
However, most GPUs use manufacturers' system architectures and compilers themselves, which usually only support applications with their own defined architectures and languages. Even if these manufacturers have released some support services for open-source software, compilers and other related software or hardware still have to use their definitions. For example, the traditional open computing language (OpenCL) compiler is AMD CLOC, which is closed source software and is only provided for X86 platform. In other words, developers are unable to modify, add instructions to, and optimize them. Therefore, there are some difficulties in the development and use. Therefore, how to provide a portable OpenCL compiler platform and an optimized compiler to improve the performance of graphics processors supporting OpenCL is a current topic.

Compiler adapted in graphics processing unit and non-transitory computer-readable medium


A switching device according to the present invention includes ion conductive layer 23 containing titanium oxide, first electrode 21 provided in contact with ion conductive layer 23, and second electrode 22 provided in contact with ion conductive layer 23 and which can supply metal ions to ion conductive layer 23.

A large number of integrated circuits are currently used in electronic apparatuses. Most of the integrated circuits that are used in the electronic apparatuses are application specific integrated circuits (ASICs). The application specific integrated circuit is a dedicated circuit designed for a specific electronic apparatus. The circuit configuration of the application specific integrated circuit, including the arrangement of logic cells (unit logic circuits for AND circuits, OR circuits, or the like) and connections among the logic cells, cannot be changed after manufacturing.
In recent years, competition for development of electronic apparatuses has been intensifying, and much effort has been made to miniaturize the electronic apparatuses. In these circumstances, much attention has been paid to programmable logic ICs (rewritable logic integrated circuits) which, even after manufacturing, allow specific functions from among many functions on one chip to be selected by changing the circuit configuration with electronic signals. In the programmable logic IC, a plurality of logic cells are connected together via switches. Typical examples of the programmable logic IC include an FPGA (Field-Programmable Gate Array) and a DRP (Dynamically Reconfigurable Processor).
In spite of much attention being paid to the programmable logic IC, the number of examples in which the programmable logic IC is mounted in the electronic apparatus has been limited. The reason is as follows. In the conventional programmable logic IC, switches connecting logic cells together have a large size and thus a high ON-resistance. Thus, a configuration having a small number of logic cells each including a large number of transistors has been adopted in order to minimize the number of switches installed. This reduces the degree of freedom of the combination of the logic cells, limiting the functions of the programmable logic IC. That is, the large size and high on resistance of the switch limit the functions of the programmable logic IC. The mounting of the programmable logic IC in the electronic apparatus is thus limited.
Thus, the size and ON-resistance of the switch, connecting the logic cells together, need to be reduced in order to provide the programmable logic IC with various functions to promote the mounting of the programmable logic IC in the electronic apparatus and the like. As a switch that meets this demand, a switching device has been proposed which utilizes metal ion migration and electrochemical reaction in an ion conductor (a solid through which ions can migrate freely) (see, for example, WO 2003/094227). The switching device disclosed in WO 2003/094227 has a smaller size and a lower ON-resistance than semiconductor switches (MOSFETs) often used in the conventional programmable logic ICs.
FIG. 7 is a schematic sectional view showing the configuration of the switching device disclosed in WO 2003/094227. The switching device has first electrode 11, and second electrode 12 laminated on first electrode 11 via ion conductive layer 13 (referred to as a "solid electrolyte" in Patent Document 1). In this case, ion conductive layer 13 serves as a medium through which metal ions are conducted.
Now, the operation of the switching device shown in FIG. 7 will be described. Second electrode 12 is grounded, and a negative voltage is applied to first electrode 11. Then, metal in second electrode 12 is dissolved into ion conductive layer 13 as metal ions. The metal ions in ion conductive layer 13 are precipitated on a surface of first electrode 11 as metal. The precipitated metal forms metal dendrite connecting first electrode 11 and second electrode 12. The metal dendrite is a metal precipitate resulting from precipitation of the metal ions contained in ion conductive layer 13. The metal dendrite electrically connects first electrode 11 and second electrode 12 together to turn on the switch.
On the other hand, with the switch in the on state, second electrode 12 is grounded, a positive voltage is applied to first electrode 11. Then, the metal dendrite is dissolved into ion conductive layer 13, and a part of the metal dendrite is severed. This electrically disconnects first electrode 11 from second electrode 12 to turn off the switch. Electrical characteristics change before the electric connection is completely cut. For example, the electric resistance between first electrode 11 and second electrode 12 increases or inter-electrode capacitance changes before the electric connection is finally cut. Furthermore, a desirable material for first electrode 11 is a material which does not feed metal ions into the ion conductive layer when the voltage is applied to first electrode 11. Additionally, the negative voltage may be applied to first electrode 11 again in order to change the off state to the on state.
JOURNAL OF SOLID STATE CIRCUITS, Vol. 40, No. 1, 2005, pp. 168 to 176 proposes that such a switching device as shown in FIG. 7 be used as a wiring switch for the programmable device. Compared to conventional switches, this switching device reduces the switch area to 1/30 and the switch resistance to 1/50. Moreover, the switching device can be formed into a wiring layer. This is expected to reduce the chip area and to improve possible wiring delays. Furthermore, the size of the logic cells in the programmable logic IC can be reduced, allowing a drastic increase in circuit utilization efficiency. As a result, the chip area is reduced to 1/10, and power efficiency is tripled. The large chip size and low power efficiency of the conventional programmable logic IC limits the range of applications thereof. However, programmable logic ICs using such a switching device as shown in FIG. 7 can cover a wider application range.
WO 2003/094227 discloses Cu/Cu2S, Ag/Ag2S, and the like as examples of a combination of an electrode material and an ion conductive layer. Any of the material combinations involves the application of a voltage (switching voltage) of about 0.05 to 0.30 [V] to first electrode 11 (FIG. 7) in order to change the switching device from the on state to the off state or from the off state to the on state. On the other hand, for logic signals used in the programmable logic IC as signals, a voltage indicating one of two types of information, that is, an operating voltage for the logic IC, is Vdd [V]. A voltage indicating the other type of information is 0.0 [V]. A Vdd [V] that is currently often used in silicon integrated circuits is about 1.0 to 2.0 [V].
The switching device disclosed in WO 2003/094227 has a switching voltage of at most 0.30 [V]. Consequently, if the Vdd of the logic signal is 1.0 [V], the switching voltage is lower than Vdd. Thus, every time a logic signal with the voltage Vdd [V] is input to the switching device, a voltage of 1.0 [V] is applied to the first electrode. The logic signal may thus change the state of the switch. In this case, a fatal problem may occur; the switch may not function. Therefore, a higher switching voltage needs to be set to stabilize the switching device.
Furthermore, a time equal to or longer than the product life (generally 10 years) of the programmable logic IC is required to hold the state of the switching device (the time required to maintain non-volatility). Heat energy at room temperature is generally 26.0 [meV]. Thus, when the switching voltage is closer to 26.0 [mV], thermal noise may be generated and is likely to cause the switching state to change voluntarily. Therefore, the switching voltage also needs to be increased in order to allow the state of the switching device to be maintained for a longer time.

Switching device, rewritable logic integrated circuit, and memory device


A method and apparatus for channel sensing in a wireless communication device is provided. A self-signal intentionally transmitted to a first wireless device by another wireless communication device is detected in a signal received by the first wireless device. An original self-signal transmitted by the second wireless device is reconstructed from the detected self-signal. The reconstructed self-signal is then suppressed in the received signal and channel sensing is performed on the remaining signal. If the self-signal cannot be detected and verified in the received signal, the second wireless device may be requested to retransmit a modified self-signal and a predetermined number of attempts made to detect and verify the self-signal. Results of channel estimation performed on the received signal may be used in reconstructing the original self-signal. The channel estimation may include information from a plurality of frames in the received signal.

Use of the radio frequency (RF) spectrum is regulated by governmental entities in each country. Typically, a fixed band of the spectrum is allocated to one or more types of primary users. Certain bands of the spectrum may be overloaded, such as cellular network bands, while other bands may be underused, such as television and radio broadcast bands. For example, a town may have only a few television stations or a radio station may cease broadcasting at a certain time of day. Previously, non-licensed users were prevented from using such underused bands of the spectrum.
More recently, regulatory agencies have opened up some bands of the RF spectrum to secondary users, provided such secondary users avoid interference with primary users. Interference is avoided by deferring to primary users when such users are operating and on the portions of a band in which they are operating. Such opportunistic use of under-utilized RF spectrum for wireless communication is often referred to as cognitive radio.
In order to avoid interference with primary users of a band, a secondary user may perform channel sensing on one or more channels of the band to determine whether a primary user is currently using the channels. If such use is sensed, the secondary user may attempt to use other channels or delay its use of the first channels until such use will not interfere. A secondary user may already be using a channel when a cognitive radio attempts to use it or a primary user may begin using a channel while the secondary user is using it. In either case, the secondary user is required to sense the primary user's activity and avoid use of the channel.
Where no use is currently being made of a channel by a collection of intercommunicating cognitive radios (a cell), the radios of the cell may simply receive signals on the channel and use one of several known techniques for determining whether the channel is already in use. Where the cell is already using a channel, the radios of the cell must periodically cease transmitting on the channel to sense use of the channel by a primary user. Such a channel sensing technique may be referred to as quiet period channel sensing.
Alternatively, the radios of a cell may employ channel-hopping: using a subset of the available channels in a band and, at regular intervals, hopping to a different subset, after checking that the new subset is not already in use. In this way, the secondary users will avoid hopping onto channels already in use by primary user and within a predetermined period, hop off of channels that a primary user has begun using. Such hopping techniques may also be used among subcarriers within a single channel.
All these techniques for channel sensing result in the cognitive radios of a cell using less than the full bandwidth available in an RF band. There is therefore a need for a more efficient technique of channel sensing. More particularly, there is a need for channel sensing while continuing to use channels and subcarriers of an RF band.

Channel sensing based on self-signal suppression


According to one embodiment, a measuring apparatus includes an ultrasonic transmitter, an ultrasonic receiver and an estimator. An ultrasonic transmitter transmits, as a transmission signal, an ultrasonic beam in a plurality of directions. An ultrasonic receiver receives, as received signals, reflected waves of the transmission signal from the plurality of directions, one received signal including a plurality of reflected waves when the transmission signal is transmitted to one direction of the plurality of directions. An estimator that estimates range information from the received signals, based on preliminarily obtained received signals and a preliminarily obtained distance to an object.

In recent years, demands for 2-dimensional range sensors or 3-dimensional range sensors for use in automatic driving, or detection of an obstacle, or mapping, to be mounted on a mobile robot have been increasing.
Generally, a millimeter-wave radar or camera, etc. is mounted on a vehicle in which an automatic driving function is mounted. As a range sensor for use in a mobile robot, an ultrasonic sensor that detects a distance to the nearest object, a 2-dimensional range sensor such as a laser range finder (LRF), and a 3-dimensional range sensor such as a LiDAR are used, and furthermore, three-dimensional measurements, etc. using a camera have been performed.
However, a sensor using a laser is high in cost. A sensor using an image has a disadvantage of being susceptible to illumination. These 2-dimensional and 3-dimensional range sensors are high in cost as a whole.


Scheduling a sequence of tasks quickly using a task list containing a sequence of entries, with each entry indicating whether a task is enabled or disabled for execution. A scheduler block examines the sequence of entries without wasting time in examining entries between those (entries) related to a prior scheduled task and a task to be scheduled next. By not wasting time examining the entries related to the disabled entries, the next task in the sequence of tasks may be scheduled for execution quickly.

1. Field of the Invention
The present invention relates to data processing systems, and more specifically to a method and apparatus for scheduling tasks quickly in a sequential order.
2. Related Art
Data processing systems are often used to execute user applications (e.g., word processor, spreadsheets, distributed computing, etc). Applications in turn are often supported by multiple tasks. A task is generally implemented in the form of one or more instructions to provide a corresponding utility. Examples of tasks include transferring a segment of data from one memory unit to another and performing complex instructions.
Multiple tasks often need to be executed to support user applications. In general, the tasks often need to share resources such as processors, memories and interconnecting buses for execution. At least due to availability of only limited resources, only some of the tasks can generally be executed in parallel at a given time. Accordingly, data processing systems often include schedulers which coordinate and control execution of the tasks.
Schedulers typically need to be implemented meeting or balancing various requirements. One requirement is that the next task to be executed be determined quickly. In addition, it may be required to suspend a first task after partial execution, execute a second task and then switch back to the execution of the first task.
What is therefore needed is a method and apparatus for scheduling tasks meeting one or more requirements such as those noted above.

Scheduling tasks quickly in a sequential order

International Business Machines Corporation


A controller coupled to a host system, an external storage unit and a temporary memory performs a simultaneous data transfer thereamong. The controller includes an interface unit coupled to the host system, a buffer memory coupled to the external storage unit, a data transfer control unit coupled to the interface unit and the buffer memory, and a bus interconnecting the interface unit, the buffer memory and the temporary memory to one another. The data transfer control unit includes sequencing circuitry for generating first and second enable-signals substantially simultaneously and then generating one of first and second read signals and one of second and first write signals while instructing the temporary memory to fetch data onto the bus. The interface unit is supplied with the first enable-signal, the first read signal and the first write signal from the sequencing circuitry for outputting data therein onto the bus in response to the first read signal while receiving the first enable-signal and for fetching data on the bus in response to the first write signal while receiving the first enable-signal. The buffer memory is supplied with the second enable-signal, the second read signal and the second write signal from the sequencing circuitry for outputting data therein onto the bus in response to the second read signal while receiving the second enable-signal and for fetching data on the bus in response to the second write signal while receiving the second enable-signal.

The present invention relates to a controller for controlling an external storage or sub-memory unit such as a hard disk drive, a floppy disk drive, an optical disk drive and a cartridge magnetic tape drive employed in an information processing system and, more particularly, to an improvement in a data transfer control unit in such a memory controller.
An information processing system, which processes, manages and stores a great amount of data, includes one or more external storage or sub-memory units described above in addition to a main memory unit. A memory controller is thus required which intervenes between a host processor and the sub-memory unit to perform a data transfer operation therebetween. In general, such a memory controller includes an interface control unit for interfacing with the host processor, a buffer memory for temporarily storing data read from or to be written into the sub-memory unit, and a data transfer control unit for performing a data transfer operation between the interface control unit and the buffer memory. In accordance with requests from the host processor, the memory controller writes data from the host processor into the sub-memory unit and reads data from the sub-memory unit to the host processor.
The host processor often requires to obtain data that are the same as the data which were written into or read from the sub-memory unit by the previous request. Even in such a case, if the memory controller is constructed to perform the data read operation from the sub-memory unit whenever the access request is generated from the host processor, it takes a relatively long time to transfer the required data to the host processor. This is because the access speed of the sub-memory unit is slow.
In order to solve this problem, it has been proposed to apply a so-called cache memory technique to the memory controller for the sub-memory unit. Specifically, the memory controller is constructed to be connected with or to include a cache memory for storing a part of data written in the sub-memory unit and the data transfer control unit is added with a function of controlling the cache memory. Accordingly, if the cache memory stores data that are the same as the data required by the host processor, those data are read out of the cache memory and then transferred via the interface unit to the host processor. No data read operation from the sub-memory unit is thus required. On the other hand, in case where the cache memory does not store the data required by the host processor, the data read operation from the sub-memory unit is initiated. The data read from the sub-memory unit is first temporarily stored in the buffer memory. The data thus stored in the buffer memory is then transferred to the cache memory under the control of the data transfer control unit. Thereafter, the data read operation from the cache memory is initiated, so that the data is transferred to the interface unit from the cache memory and finally to the host processor.
Thus, the data transfer speed is improved remarkably in case of the cache memory storing the required data, but the data transfer speed is lowered extremely in the case of the cache memory not storing the required data since the data read out of the sub-memory unit is transferred from the buffer memory to the interface unit under the intervention of the cache memory. Moreover, when the host processor requires to write data into the sub-memory unit, that data is first stored into the cache memory from the interface unit and thereafter transferred to the buffer memory from the cache memory. The data write speed into the sub-memory unit is thereby lowered.

Memory controller for sub-memory unit such as disk drives