Database network system

Abstract

A database network system is capable of recognizing in a short time (within several minutes) the state of damage or the like of city lifelines (waterworks, electricity, and gas supplies) over a whole city. A database network system according to the present invention includes a center station, relay database stations (RDSs), and terminal stations. A terminal station group includes a plurality of terminal stations for acquiring changing information to accumulate the information as data and for transmitting the data as requested. Each of the plurality of relay database stations (RDSs) is arranged for the terminal station group, and accumulates pieces of information sequentially received from the terminals as specific data and other data and transmits the data as requested. The center station sequentially receives parts of the specific data and other data of an arbitrary one of the relay database stations (RDSs) from the corresponding relay database station, performs a receiving operation of all the data and the specific information data a plurality of times by performing the receiving operation a plurality of times, and accumulates the data as needed.

Claims

What is claimed is:

1. A multilayer polling database network system for collecting information, comprising:

a lower polling layer having a plurality of terminal station groups, each group including a plurality (P.sub.2) of terminal stations, each terminal station acquiring information, accumulating the information as data, and transmitting the data during a lower-layer polling period (T.sub.2);

a relay database station layer having a plurality (P.sub.1) of relay database stations, each relay station database communicating with a corresponding terminal station group for acquiring information (b.sub.1) from the terminal stations, extracting specific information (b.sub.2) from the information (b.sub.1) acquired from the terminal stations, dividing the information (b.sub.1) into n (n=1, 2, 3 . . . ) groups and holding the divided information for a predetermined period of time; and

a center station for sequentially polling the relay database stations and acquiring (b.sub.2 +b.sub.1 /n).times.P.sub.2 bytes of information during an upper-layer polling period (T.sub.1).

2. A database network system according to claim 1, wherein the upper-layer polling period (T.sub.1) and lower-layer polling period (T.sub.2) have the following relations:

T.sub.1.gtoreq.T.sub.2

T.sub.1 =[k.times.(b.sub.2 +b.sub.1 /n) P.sub.2.times.P.sub.1 ]/r.sub.1

T.sub.2 =k.times.b.sub.1 x P.sub.2 /r.sub.2

where

k: constant

r.sub.1 : the effective data transmission rate between the center station and the relay database stations

r.sub.2 : the effective data transmission rate of the lower polling layer.

3. A database network system according to claim 1, wherein the information is city utility information and the terminal stations are living unit terminals of houses.

4. A database network system according to claim 1, wherein the specific information (b.sub.2) extracted from the information (b.sub.1) is selected based on a degree of emergency.

5. A database network system according to claim 1, wherein the center station comprises a main database which holds the specific information data and the data for a predetermined period of time to provide a history of the operation.

6. A database network system according to claim 1, wherein the information acquired by the terminal station includes at least one of data for reading meter values, data for collecting/monitoring information related to various maintenance jobs, and information data related to security, care of elderly people, water pressures of fire hydrants, and monitors of air-conditioners.

7. A database network system according to claim 1, wherein the plurality of relay database stations includes at least one upper-layer relay database station group and a plurality of lower-layer relay database station groups associated with one of the upper-layer relay database stations,

the database relay stations of the lower-layer relay database station group collect information from the terminal station groups, and

the center station collects information from the upper-layer relay database stations.

8. A method of collecting data, comprising:

collecting data regarding utility networks at a number (P.sub.2) of terminal stations;

arranging the terminal stations into a plurality of groups;

associating each group of terminal stations with at least one of a number (P.sub.1) of relay database stations;

transmitting the data (b.sub.1) from the groups of terminal stations to the associated relay database station during to a second polling period (T2);

extracting selected information (b.sub.2) from the transmitted data (b.sub.1) at the relay database stations;

dividing the data (b.sub.1) into n (n=1, 2, 3 . . . ) groups; and

sequentially polling the relay database stations with a center station to acquire (b1+b2/n)*P.sub.2 bytes of information during a first polling period (T1).

9. The method of claim 8, further comprising holding the data b.sub.1 at the relay database stations for a predetermined period of time.

10. The method of claim 8, wherein the first polling period (T.sub.1) and the second polling period (T.sub.2) have following relations:

T.sub.1.gtoreq.T.sub.2

T.sub.1 =[k.times.(b.sub.2 +b.sub.1 /n) P.sub.2.times.P.sub.1 ]/r.sub.1

T.sub.2 =k.times.b.sub.1.times.p.sub.2 /r.sub.2

where

k: constant

r.sub.1 : the effective data transmission rate between the terminal stations and the relay database stations

r.sub.2 : the effective data transmission rate between the relay database stations and the center station.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a city lifeline information collection system capable of collecting information related to lifeline services such as gas supplies, waterworks, and electricity, in particular, for rapidly collecting data (specific data) related to a state of emergency.

2. Description of the Related Art

U.S. Pat. No. 5,689,233, U.S. Pat. No. 4,888,706, U.S. Pat. No. 4,322,842, and U.S. Pat. No. 5,894,422 are related to a lifeline information collecting system, an emergency information collection, or emergency information offering system. U.S. Pat. No. 5,689,233 discloses an emergency information offering system. An object of the invention is to attain proper information collecting and offering functions by combining information infrastructures and public infrastructures upon emergencies involving lifeline facilities.

Problems caused when conventional communication equipment is used will be described below in the case where a telephone network is used.

A collection system using a telephone network is used in practice to collect general pieces of lifeline information relating to houses; for example the state of gas supplies, waterworks, and electricity, or the state in which undesirable conditions occur, however, the information collection system using the telephone line is not effective when communications are congested during a disaster. In addition, when pieces of information of 100 bytes per terminal, including information on gas supplies, waterworks, and electricity, are to be collected for 200,000 terminals or more, the number of hours required when the telephone network is used is determined by 30 seconds.times.200,000 terminals=1,667 hours. Therefore, a continuous monitoring system cannot be easily realized by using a telephone network.

The problems to be solved by the present invention are as follows.

1. An information collection/monitoring system for recognizing in a short time (within several minutes) the state of damage of city lifelines (waterworks, electricity, and gas supplies) caused by a large earthquake over the whole city has not been developed in Japan or other countries. The development of such a system is considered as a problem which must be quickly solved for a countermeasure against disasters.

2. The present invention develops a system which recognizes information on water meters, electricity meters, and gas meters installed in houses and collects/monitors this information over the whole city in real time, so as to solve the above problem.

3. Since this system is an information collection system used during emergencies, delay and interruption of information collection caused by congestion of communications cannot be permitted. The problem of congestion cannot be solved by using a conventional communication system, and should be solved by developing a dedicated information collection system.

4. Since a dedicated system requires its functions and performances to be regulated, it is a technical problem to develop a system appropriate to the object.

5. It has been a difficult technical problem to develop an information collection system which continuously monitors lifelines of the whole city and has a function of collecting emergency information in a short time, while at the same time collecting detailed lifeline information.

6. This technical problem is solved by a new network configuration technique, i.e., a database network, obtained by combining high-speed databases distributed in a multi-layer radio polling system. When a disaster occurs, in order to recognize the state of the disaster, it is required to recognize the states of the lifelines of all houses within several minutes. In addition, in a disaster, communications are congested by events occurring at the same time. Therefore, assurance of communications is required evenduring disasters.

7. When a disaster occurs, in order to recognize the state of the disaster, the condition of the system up to the occurrence of the disaster must be recognized, and it must be recognized that the system is operating normally.

SUMMARY OF THE INVENTION

It is a main object of the present invention to provide a new database network system which is different from a conventional communication system.

It is another object of the present invention to constitute an information collection/monitoring system for recognizing in a short time (within several minutes) the state of damage of city lifelines (waterworks, electricity, and gas supplies) caused by a large earthquake over a whole city by using the database network system.

It is still another object of the present invention to provide a database network system, according to the above objects, which can recognize a state of the lifelines immediately before the damage caused by the large earthquake.

To this end, according to one aspect of the present invention, there is provided a database network system for collecting information comprising a terminal station group constituted by a plurality of terminal stations for acquiring changing information, to accumulate the information as data, and to transmit the data in accordance with a request, a plurality of relay database stations, each arranged for the terminal station group, for accumulating pieces of information sequentially received from the terminals as specific data and other data, and for transmitting the data in accordance with a request, and a center station for sequentially receiving parts of the specific data and the other data of an arbitrary one of the relay database stations from the corresponding relay database station, for performing a receiving operation of all the data and the specific information data a plurality of times by performing the receiving operation a plurality of times, and for accumulating all the data and the specific information data as needed.

The plurality of relay database stations includes at least one upper-layer relay database station group and a plurality of lower-layer relay database station groups arranged for one of the upper-layer relay database stations, the stations of the lower-layer relay database station group collect information of the terminal station group constituted by the plurality of terminal stations, and the center station collects information from the upper-layer relay database station.

The changing information is city lifeline information of gas supplies, electricity, waterworks, and the like, and the terminal stations are living unit terminals of houses and the like.

Specific information is extracted from changing house terminal information depending on a degree of emergency, at least two types of information including the original house terminal information:are generated, and the at least two types of information are collected in the center station for a collection time which changes depending on the degree of emergency.

The database network system is continuously operated, and a main database of the center station is designed to always hold the history of the operation by accumulating specific information data and the other data for a predetermined period of time.

As a combination of the pieces of changing information, one combination of data for reading meter values included in one of lifeline data of meters, data for collecting/monitoring information related to various maintenance jobs, and information data related to security, care of elderly people, water pressures of fire hydrants, and monitors of air-conditioners can be employed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a conceptual diagram of a lifeline information collection/monitoring system constituted by combining an asynchronous two-layer polling system serving as a first embodiment of a database network system according to the present invention and a high-speed database.

FIG. 2 is a conceptual diagram of a lifeline information collection/monitoring system constituted by combining an asynchronous three-layer polling system serving as a second embodiment of the database network system according to the present invention and a high-speed database.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of systems according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a conceptual diagram of a lifeline information collection/monitoring system constituted by combining an asynchronous two-layer polling system serving as the first embodiment of a database network system according to the present invention and a high-speed database.

A center station 1 comprises a main database 1A for arranging collected data and accumulating the data for a required period of time. The center station 1 sequentially polls relay database stations. (RDS) 3.sub.1 to 3.sub.p1 of a relay database station group 3 to collect data.

The relay database stations 3.sub.1 to 3.sub.p1 are related to corresponding terminal groups, and sequentially poll terminal stations, e.g., the terminal stations each corresponding to one household serving as a living unit, to collect data.

Although each of the relay database stations 3.sub.1 to 3.sub.p1 has the same function as that of the main database 1A, this is omitted in FIG. 1 for descriptive convenience.

Terminal station groups 5.sub.1 to 5.sub.p1 are related to the relay database stations 3.sub.1 to 3.sub.p1, respectively. The terminal station group 5.sub.1 related to the relay database station 3.sub.1 includes p.sub.2 terminal stations 5.sub.11 to 5.sub.1p2. The relay database station 3.sub.1 sequentially polls terminal stations 5.sub.11 to 5.sub.1p2 to collect data. The relay database station 3.sub.2 sequentially polls terminal stations 5.sub.21 to 5.sub.2p2 to collect data. The relay database station 3.sub.p1 sequentially polls terminal stations 5.sub.p11 to 5.sub.p1p2 to collect data. The sequential polling operations in the relay database stations are performed in parallel or almost in parallel to each other. Upper-layer communication is indicated by a dotted line 6, and an effective data transmission rate of communication between the center station 1 and the relay database station 3.sub.1 or the like is represented by r.sub.1. Lower-layer communication is indicated by a dotted line 8, and an effective data transmission rate of communication between the relay database station 3.sub.1 and a terminal station or the like is represented by r.sub.2. As communication media, various media including priority communication in, especially, the lower-layer communication are expected. However, a radio communication medium is used in this embodiment.

As the first embodiment of the database network system, a system for recognizing within ten minutes the state of damage of city lifelines (waterworks, electricity, or gas supply systems) caused by a large earthquake will be described below.

Signals (lifeline information) representing the states of water, gas, and electricity supplies are collected and continuously monitored through meters installed in houses. Collection, analysis, and accumulation/holding of the lifeline information are performed by using a dedicated network structured by combining radio communication devices and computers. In this case, each house corresponds to a terminal station, and information obtained from so-called electronic meters (or microcomputer meters) is used as the lifeline information. The electronic meter has functions of performing collection, holding, transmission, updating, and the like, of information data (quantity used or the like).

Examples of conditions of the database network system are as follows.

1. The number of house terminals: about 260,000

2. Lifeline information (per house terminal):

waterworks: 20 bytes

gas: 20 bytes

electricity: 20 bytes

other: 40 bytes

total: 100 bytes

Information which has a high degree of emergency and must be continuously monitored is

10 bytes/house terminal

3. Pieces of information having a high degree of emergency and which must be continuously monitored are periodically collected from the 260,000 house terminals every several minutes and updated. The collection/updating time is set at 10 minutes or less. In addition, a time record of the last 24 hours is always held.

4. All the collected pieces of lifeline information are updated as needed (or periodically), and the latest contents of the lifeline information are held in the database in the system.

The realization of a system satisfying the above requests uses the techniques (combinations thereof) described below.

1. A multi-layer radio polling system is used.

2. A conceptual view of the configuration of a lifeline information collection system constituted by combining a two-layer polling system and a high-speed database is shown in FIG. 1.

3. Pieces of house terminal lifeline information collected by a polling scheme (1) have given addresses, and (2) are classified by designated items. Therefore, since the pieces of lifeline information collected from the house terminals have a database structure, a computer (PC) for acquiring and processing the pieces of lifeline information is regarded as a database, and functions and characteristics of the database are effectively used.

4. In addition to arrangement of the main database device 1A in the center station 1, databases are distributed in the relay stations 3.sub.i.

5. Databases capable of updating a large quantity of data at high speed are used as the main database device 1A and the relay station database devices,.

6. A relay station in which a database having a high-speed data updating function is arranged is called a relay database station (to be referred to as an RDS hereinafter).

7. In FIG. 1, the RDS mainly has four functions.

(1) Communication control of a lower polling layer.

(2) Acquisition of lifeline information (b.sub.1 bytes/terminal, in this embodiment b.sub.1 =100 bytes) from a house terminal.

(3) Data having a high degree of emergency or specific data is extracted, and data sets (called event change information or specific data information) of (b.sub.2 bytes/terminal, in this embodiment b.sub.2 =10 bytes).times.p.sub.2 are generated.

(4) Division of lifeline information 100 bytes/terminal (the number of divided portions is n), and holding of the divided portions for a predetermined period of time.

8. The center station 1 sequentially polls p.sub.1 relay database stations to collect information. For one polling period, [(10+100/n).times.p.sub.2 ] bytes are collected from each RDS.

9. As a result of item 7, every one polling period, event change information of (10 bytes/terminal).times.p.sub.2.times.p.sub.1 is collected in the center station 1. Here, p.sub.2.times.p.sub.1 is the total number of house terminals.

10. As a result of item 7, every n polling periods, lifeline information of (100 bytes/terminal).times.p.sub.2.times.p.sub.1 is collected in the center station. More specifically, every n periods, pieces of lifeline information from all the house terminals are collected.

11. According to items 9 and 10, the following is understood: From all the house terminals to the center station 1, (1) event change information having a high degree of emergency is transmitted for a short time, and (2) all pieces of lifeline information are transmitted. The above two objects can be achieved by using one information transmission path.

12. An upper-layer polling period T.sub.1 is given by the following equation:

T.sub.1 =[8.times.(10+100/n) p.sub.2.times.p.sub.1 ]/r.sub.1

where r.sub.1 is the effective data transmission rate of the upper polling layer. When the number of all house terminals p.sub.2.times.p.sub.1 is given, the polling period T.sub.1 is mainly determined by r.sub.1.

13. When the upper limit of T.sub.1 is given to use a network, according to the above equation, the lower limit of r.sub.1 is almost determined.

14. A polling period T.sub.2 of the lower polling layer is given by:

T.sub.2 =8.times.100.times.p.sub.2 /r.sub.2,

where r.sub.2 is the effective data transmission rate of the lower polling layer.

15. The effective data transmission rate r.sub.1 of the upper polling layer is given by:

1/r.sub.1 =1/r.sub.d1 +1/r.sub.u1,

where r.sub.d1 is a data transmission rate in bits per second (bps) of a communication line for connecting an RDS and the center station 1 to each other, and r.sub.u1 is a data updating rate of a database in the center station.

16. The effective data transmission rate r.sub.2 of the lower polling layer is given by:

1/r.sub.2 =1/r.sub.d2 +1/r.sub.u2,

where r.sub.d2 is a data transmission rate of a transmission line for connecting house terminal stations and an RDS, and r.sub.u2 is a data updating rate of a database in the RDS.

17. The upper polling layer and the lower polling layer operate asynchronously. In order to ensure that data collected in the center station and the upper-layer RDS are the latest data collected in the RDS, the condition

T.sub.1.gtoreq.T.sub.2 must be satisfied.

18. When the condition

T.sub.1 =T.sub.2 is satisfied, all the data collected in the lower polling layer are sent to the upper polling layer. For this reason, the data transfer efficiency is 100%.

19. At this time, the effective data transmission rate r.sub.2 of the lower polling layer and the effective data transmission rate r.sub.1 of the upper polling layer have the following relationship:

r.sub.2 =r.sub.1.times.(1/p.sub.1).times.[100/(10+100/n)],

where (1/p.sub.1) is a required rate reduction effect obtained by a parallel operation of p.sub.1 lower polling cells, and [100/(10+100/n)] is an adjustment effect obtained by a ratio of quantities of transmission information.

20. Actually, r.sub.2 is set to be slightly larger than the above value:

r.sub.2 =r.sub.1.times.(1/p.sub.1).times.[100/(10+100/n)].times.(1+.delta.)

where .delta.<<1

21. The memory capacity required for a database in an RDS:

(1) 100.times.p.sub.2 bytes: 100 bytes of data are collected from p.sub.2 house terminals and stored.

(2) 10.times.p.sub.2 bytes: 10 bytes are extracted from 100 bytes, and 10 bytes.times.p.sub.2 are stored.

22. The memory capacity required for a database in the center station:

(1) 100.times.p.sub.2.times.p.sub.1 bytes: Pieces of lifeline information collected from all the house terminals are stored and held.

(2) 10.times.p.sub.2.times.p.sub.1.times.(24.times.60/T.sub.1) bytes: Pieces of event change information collected from all the house terminals for the latest 24 hours are stored and held.

23. (Data quantity of each layer of system)

                         TABLE 1
                          UNIT       QUANTITY OF INFORMATION        TOTAL
     QUANTITY
                        (NUMBER)           (BYTES)/UNIT                (BYTES)
      HOUSE TERMINAL   p.sub.2 .times. p.sub.1              100
     100 .times. p.sub.2 .times. p.sub.1
          LEVEL
        RDS LEVEL       p.sub.1        100 .times. p.sub.2      100 .times.
     p.sub.2 .times. p.sub.1
                                       10 .times. p.sub.2       10 .times.
     p.sub.2 .times. p.sub.1
      CENTER STATION        1      100 .times. p.sub.2 .times. p.sub.1  100
     .times. p.sub.2 .times. p.sub.1
                                   10 .times. p.sub.2 .times. p.sub.1 .times.
     24 .times. 60/T.sub.1  10 .times. p.sub.2 .times. p.sub.1 .times. 24
     .times. 60/T.sub.1

                         TABLE 2
                          UNIT       QUANTITY OF INFORMATION        TOTAL
     QUANTITY
                        (NUMBER)           (BYTES)/UNIT                (BYTES)
      HOUSE TERMINAL   p.sub.3 .times. p.sub.2 .times. p.sub.1              100
                  100 .times. p.sub.3 .times. p.sub.2 .times. p.sub.1
          LEVEL
       LOWER-LAYER     p.sub.2 .times. p.sub.1      100 .times. p.sub.3
     100 .times. p.sub.3 .times. p.sub.2 .times. p.sub.1
        RDS LEVEL                      10 .times. p.sub.3       10 .times.
     p.sub.3 .times. p.sub.2 .times. p.sub.1
       UPPER-LAYER      p.sub.1    100 .times. p.sub.3 .times. p.sub.2  100
     .times. p.sub.3 .times. p.sub.2 .times. p.sub.1
        RDS LEVEL                  10 .times. p.sub.3 .times. p.sub.2  10
     .times. p.sub.3 .times. p.sub.2 .times. p.sub.1
                                   20 .times. p.sub.3 .times. p.sub.2  20
     .times. p.sub.3 .times. p.sub.2 .times. p.sub.1
      CENTER STATION        1      100 .times. p.sub.3 .times. p.sub.2 .times.
     p.sub.1  100 .times. p.sub.3 .times. p.sub.2 .times. p.sub.1
                                   10 .times. p.sub.3 .times. p.sub.2 .times.
     p.sub.1 .times. 24 .times. 60/T.sub.1  10 .times. p.sub.3 .times. p.sub.2
     .times. p.sub.1 .times. 24 .times. 60/T.sub.1
                                   20 .times. p.sub.3 .times. p.sub.2 .times.
     p.sub.1 .times. F 20 .times. p.sub.3 .times. p.sub.2 .times. p.sub.1
     .times. F

                                                 TABLE 3
                                         QUANTITY OF INFORMATION     COLLECTION
     TIME
                                                 (BYTES)                  (MIN)
      DETAILED LIFELINE INFORMATION    100 .times. p.sub.3 .times. p.sub.2
     .times. p.sub.1  T.sub.1 .times. (n.sub.3 + n.sub.2 .times. 5)
         EVENT CHANGE INFORMATION       10 .times. p.sub.3 .times. p.sub.2
     .times. p.sub.1       T.sub.1
         MAINTENANCE INFORMATION        20 .times. p.sub.3 .times. p.sub.2
     .times. p.sub.1  T.sub.1 .times. (n.sub.3 + n.sub.2)

• Inventors
  Mizushina, Shizuo; Adachi, Atsushi;
• Assignee
  Hamanen Co., Ltd. (Hamamatsu, JP)
• Published
  Nov-19-2002
• Current US Classes:
  707/104.1
• Application #
  522033
• International Classes
  G06F 017/30
• Field of Search
  707/104.1
• Examiner
  Amsbury; Wayne
• Agent
  Venable, Frank; Robert J.
• US Patent References:
  4322842
  4888706
  5689233
  5732510
  5761083
  5943673
  6121875
  6169476
  6236365
  6246320
  6356554
  6352222