Partial Global Indexing for Location-Dependent Query Processing

2007 ◽  
pp. 739-743
Author(s):  
J. Jayaputera
Keyword(s):  
Simulation Model ◽  
Query Processing ◽  
Access Time ◽  
Current Cell ◽  
Local Storage ◽  
Location Dependent Query ◽  
Future Work

The idea of this article is based on the parallel indexing concept (Taniar & Rahayu, 2002) in which an indexed object residing in a BS is either fully, partially, or not replicated to others BSs. Therefore, every server contains either partial or all indexes of other servers. In our proposed approach, whenever the requested results return from neighboring cells, we append the resulting items to the current cell. This implies that when the next user sends a request, the current cell needs to look up its own index first to verify if the data is in its local storage. If the data is not present, the current server sends a request to the neighboring cells on behalf of the client; otherwise, the current server directly sends the requested query to the client. We have evaluated our proposed approach and showed that the access time can be reduced by a factor of two.The next section of this article describes some related work. We then describe our proposed work and the simulation model, and we compare the performance of our proposed technique to other techniques. Finally, we conclude the article and suggest future work.

scholarly journals ACCESS TIME OF EMERGENCY VEHICLES UNDER THE CONDITION OF STREET BLOCKAGES AFTER A LARGE EARTHQUAKE

2016 ◽  
Vol III-4/W1 ◽  
pp. 37-44
Author(s):  
N. Hirokawa ◽  
T. Osaragi
Keyword(s):  
Simulation Model ◽  
Large Scale ◽  
Large Earthquake ◽  
Access Time ◽  
Microscopic Simulation ◽  
Property Damage ◽  
Emergency Vehicles ◽  
Fire Stations ◽  
Average Access Time ◽  
Alternative Routes

The previous studies have been carried out on accessibility in daily life. However it is an important issue to improve the accessibility of emergency vehicles after a large earthquake. In this paper, we analyzed the accessibility of firefighters by using a microscopic simulation model immediately after a large earthquake. More specifically, we constructed the simulation model, which describes the property damage, such as collapsed buildings, street blockages, outbreaks of fires, and fire spreading, and the movement of firefighters from fire stations to the locations of fires in a large-scale earthquake. Using this model, we analyzed the influence of the street-blockage on the access time of firefighters. In case streets are blocked according to property damage simulation, the result showed the average access time is more than 10 minutes in the outskirts of the 23 wards of Tokyo, and there are some firefighters arrive over 20 minutes at most. Additionally, we focused on the alternative routes and proposed that volunteers collect information on street blockages to improve the accessibility of firefighters. Finally we demonstrated that access time of firefighters can be reduced to the same level as the case no streets were blocked if 0.3% of residents collected information in 10 minutes.

Study on Clustering-Based Location Dependent Query

2012 ◽  
Vol 532-533 ◽  
pp. 897-901
Author(s):  
Ming Jun Wei ◽  
Li Chun Xia ◽  
Jian Guo Jin ◽  
Qiu Hong Fan
Keyword(s):  
Mobile Computing ◽  
Query Processing ◽  
Location Analysis ◽  
System Efficiency ◽  
Analysis Algorithm ◽  
System Resources ◽  
Location Dependent Query ◽  
Special Case ◽  
New Location

This paper firstly analyzes the importance and necessity of location dependent query in the mobile computing. Then, it proposes a special case in the application of the location dependent query. That is as follows: Inquirers may send the same location dependent query in different but similar positions. However, the server will not deal with them together but treat them separately. Thus, it will not only cause the waste of system resources but also delay disposal of other queries. According to the principal of clustering we propose a new location Analysis Algorithms-similar merging location analysis algorithm (SMLA). By the algorithm, similar queries can be combined into the same query, so as to reduce the load on central servers, improve system efficiency and query processing performance.

scholarly journals Location-Dependent Query Processing Under Soft Real-Time Constraints

2009 ◽  
Vol 5 (3) ◽  
pp. 205-232 ◽  
Author(s):  
Zoubir Mammeri ◽  
Franck Morvan ◽  
Abdelkader Hameurlain ◽  
Nadhem Marsit
Keyword(s):  
Performance Evaluation ◽  
Query Processing ◽  
Real Time ◽  
Mobile Devices ◽  
Communication Cost ◽  
Time Constraints ◽  
Mobile Clients ◽  
Location Dependent Query

In recent years, mobile devices and applications achieved an increasing development. In database field, this development required methods to consider new query types like location-dependent queries (i.e. the query results depend on the query issuer location). Although several researches addressed problems related to location-dependent query processing, a few works considered timing requirements that may be associated with queries (i.e., the query results must be delivered to mobile clients on time). The main objective of this paper is to propose a solution for location-dependent query processing under soft real-time constraints. Hence, we propose methods to take into account client location-dependency and to maximize the percentage of queries respecting their deadlines. We validate our proposal by implementing a prototype based on Oracle DBMS. Performance evaluation results show that the proposed solution optimizes the percentage of queries meeting their deadlines and the communication cost.

scholarly journals ACCESS TIME OF EMERGENCY VEHICLES UNDER THE CONDITION OF STREET BLOCKAGES AFTER A LARGE EARTHQUAKE

2016 ◽  
Vol IV-4/W1 ◽  
pp. 37-44 ◽  
Author(s):  
N. Hirokawa ◽  
T. Osaragi
Keyword(s):  
Simulation Model ◽  
Large Scale ◽  
Large Earthquake ◽  
Access Time ◽  
Microscopic Simulation ◽  
Property Damage ◽  
Emergency Vehicles ◽  
Fire Stations ◽  
Average Access Time ◽  
Alternative Routes

The previous studies have been carried out on accessibility in daily life. However it is an important issue to improve the accessibility of emergency vehicles after a large earthquake. In this paper, we analyzed the accessibility of firefighters by using a microscopic simulation model immediately after a large earthquake. More specifically, we constructed the simulation model, which describes the property damage, such as collapsed buildings, street blockages, outbreaks of fires, and fire spreading, and the movement of firefighters from fire stations to the locations of fires in a large-scale earthquake. Using this model, we analyzed the influence of the street-blockage on the access time of firefighters. In case streets are blocked according to property damage simulation, the result showed the average access time is more than 10 minutes in the outskirts of the 23 wards of Tokyo, and there are some firefighters arrive over 20 minutes at most. Additionally, we focused on the alternative routes and proposed that volunteers collect information on street blockages to improve the accessibility of firefighters. Finally we demonstrated that access time of firefighters can be reduced to the same level as the case no streets were blocked if 0.3% of residents collected information in 10 minutes.

Energy and Latency Efficient Access of Wireless XML Stream

2010 ◽  
Vol 21 (1) ◽  
pp. 58-79 ◽  
Author(s):  
Jun Pyo Park ◽  
Chang-Sup Park ◽  
Yon Dohn Chung
Keyword(s):  
Query Processing ◽  
Index Structure ◽  
Access Time ◽  
Xml Data ◽  
Mobile Client ◽  
Wireless Broadcast ◽  
Efficient Access ◽  
Distributed Index ◽  
Mobile Clients ◽  
Text Content

In this article, we address the problem of delayed query processing raised by tree-based index structures in wireless broadcast environments, which increases the access time of mobile clients. We propose a novel distributed index structure and a clustering strategy for streaming XML data that enables energy and latencyefficient broadcasting of XML data. We first define the DIX node structure to implement a fully distributed index structure which contains the tag name, attributes, and text content of an element, as well as its corresponding indices. By exploiting the index information in the DIX node stream, a mobile client can access the stream with shorter latency. We also suggest a method of clustering DIX nodes in the stream, which can further enhance the performance of query processing in the mobile clients. Through extensive experiments, we demonstrate that our approach is effective for wireless broadcasting of XML data and outperforms the previous methods.

Simulation and Experiment Study on Water Vapor Condensing Heat Transfer Characteristics in Horizontal Tubes

2016 ◽  
Author(s):  
Shengchun Liu ◽  
Jiahui Zhang
Keyword(s):  
Heat Transfer ◽  
Water Vapor ◽  
Simulation Model ◽  
Cfd Simulation ◽  
Local Heat Transfer ◽  
Horizontal Tube ◽  
Local Heat ◽  
Simulation And Experiment ◽  
Condensing Heat Transfer ◽  
Future Work

Water vapor condensing process inside horizontal tube has been studied in the paper. A CFD simulation model has been developed with Fluent software. An experimental investigation has also been conducted with an 8-mm inside diameter horizontal tube. As well as the heat transfer correlations available in literatures, the CFD model has been validated against the experimental results. The discrepancy of the simulation model is within 15%. The effect of wall temperature, inlet vapor velocity and inlet superheating degree on local heat transfer coefficient has been analyzed. The simulation model can be employed in future work to develop a condensation heat transfer correlation in horizontal tube.

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