scholarly journals Frequent-Pattern-Based Broadcast Scheduling for Conflict Avoidance in Multichannel Data Dissemination Systems

2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Chuan-Chi Lai ◽  
Yu-De Lin ◽  
Chuan-Ming Liu
Keyword(s):  
Data Dissemination ◽  
Location Based Services ◽  
Frequent Pattern ◽  
Access Time ◽  
Conflict Avoidance ◽  
Multiple Channels ◽  
Broadcast Scheduling ◽  
Channel Switching ◽  
New Variant ◽  
Average Access Time

With the popularity of mobile devices, using the traditional client-server model to handle a large number of requests is very challenging. Wireless data broadcasting can be used to provide services to many users at the same time, so reducing the average access time has become a popular research topic. For example, some location-based services (LBS) consider using multiple channels to disseminate information to reduce access time. However, data conflicts may occur when multiple channels are used, where multiple data items associated with the request are broadcasted at about the same time. In this article, we consider the channel switching time and identify the data conflict issue in an on-demand multichannel dissemination system. We model the considered problem as a data broadcast with conflict avoidance (DBCA) problem and prove it is NP-complete. We hence propose the frequent-pattern-based broadcast scheduling (FPBS), which provides a new variant of the frequent pattern tree, FP ∗ -tree, to schedule the requested data. Using FPBS, the system can avoid data conflicts when assigning data items to time slots in the channels. In the simulation, we discussed two modes of FPBS: online and offline. The results show that, compared with the existing heuristic methods, FPBS can shorten the average access time by 30%.

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.

A HIGH-PERFORMANCE SEQUENTIAL MRU CACHE USING VALID-BIT ASSISTANT SEARCH ALGORITHM

2007 ◽  
Vol 16 (04) ◽  
pp. 613-626
Author(s):  
HSIN-CHUAN CHEN ◽  
JEN-SHIUN CHIANG
Keyword(s):  
High Performance ◽  
Search Algorithm ◽  
Access Time ◽  
Data Memory ◽  
Average Access Time ◽  
Cache Scheme

Most recently used (MRU) cache is one of the set-associative caches that emphasize implementation of associativity higher than 2. However, the access time is increased because the MRU information must be fetched before accessing the sequential MRU (SMRU) cache. In this paper, focusing on the SMRU cache with subblock placement, we propose an MRU cache scheme that separates the valid bits from data memory and uses these valid bits to decide to reduce the unnecessary access number of memory banks. By this approach, the probability of the front hits is thus increased, and it significantly helps in improving the average access time of the SMRU cache without valid-bit assistant search especially for large associativity and small subblock size.

scholarly journals A Stochastic Analysis of Hard Disk Drives

2011 ◽  
Vol 2011 ◽  
pp. 1-21 ◽  
Author(s):  
Field Cady ◽  
Yi Zhuang ◽  
Mor Harchol-Balter
Keyword(s):  
Stochastic Analysis ◽  
Hard Disk Drives ◽  
Closed Form Solution ◽  
Hard Disk ◽  
Form Solution ◽  
Access Time ◽  
Analytical Technique ◽  
Wide Range ◽  
Average Access Time ◽  
Memory Request

We provide a stochastic analysis of hard disk performance, including a closed form solution for the average access time of a memory request. The model we use covers a wide range of types and applications of disks, and in particular it captures modern innovations like zone bit recording. The derivation is based on an analytical technique we call “shuffling”, which greatly simplifies the analysis relative to previous work and provides a simple, easy-to-use formula for the average access time. Our analysis can predict performance of single disks for a wide range of disk types and workloads. Furthermore, it can predict the performance benefits of several optimizations, including short stroking and mirroring, which are common in disk arrays.

scholarly journals A four-phase data replication algorithm for data grid

2015 ◽  
Vol 4 (1) ◽  
pp. 163 ◽  
Author(s):  
Alireza Saleh ◽  
Reza Javidan ◽  
Mohammad Taghi FatehiKhajeh
Keyword(s):  
Large Scale ◽  
Data Replication ◽  
Data Grid ◽  
Data Availability ◽  
Access Time ◽  
File Transfer ◽  
System Availability ◽  
Large Scale Data ◽  
Effective Network ◽  
Average Access Time

<p>Nowadays, scientific applications generate a huge amount of data in terabytes or petabytes. Data grids currently proposed solutions to large scale data management problems including efficient file transfer and replication. Data is typically replicated in a Data Grid to improve the job response time and data availability. A reasonable number and right locations for replicas has become a challenge in the Data Grid. In this paper, a four-phase dynamic data replication algorithm based on Temporal and Geographical locality is proposed. It includes: 1) evaluating and identifying the popular data and triggering a replication operation when the popularity data passes a dynamic threshold; 2) analyzing and modeling the relationship between system availability and the number of replicas, and calculating a suitable number of new replicas; 3) evaluating and identifying the popular data in each site, and placing replicas among them; 4) removing files with least cost of average access time when encountering insufficient space for replication. The algorithm was tested using a grid simulator, OptorSim developed by European Data Grid Projects. The simulation results show that the proposed algorithm has better performance in comparison with other algorithms in terms of job execution time, effective network usage and percentage of storage filled.</p>

Implementasi Distributed File Server pada Apache Web Server

2013 ◽  
Vol 4 (2) ◽  
pp. 84-88
Author(s):  
Novita Belinda Wunarso ◽  
Andrias Rusli ◽  
Michelle Angelica ◽  
Arabella Margaret Salim
Keyword(s):  
Web Server ◽  
Access Time ◽  
Storage Space ◽  
File Server ◽  
Index Terms ◽  
Average Access Time ◽  
The Web

In  this  research,  a  Distributed  File  Server (DFS) is developed to manage the need of a large storage space in the server, especially when the multimedia files are saved permanently in the web server. In the development, Apache Web Server is used with 1 computer as the main server, 2 computers as file servers, and 1 computer as the client who sends request. The result from the implementation of the DFS is the usage of main server’s storage space can be reduced by 99,77% from the full usage condition, causing an optimization in the web server. Another parameter is also being tested by the implementation of the DFS, which is the index.html page’s average access time. When only one server is being used, the average access time is 2,327 second. Whereas, when three servers are being used, the average access time is 5,577 second. Index Terms - Apache, distributed file server, web server optimization, average access time

Spiking Neural P Systems with Extended Channel Rules

2020 ◽  
Vol 31 (01) ◽  
pp. 2050049 ◽  
Author(s):  
Zeqiong Lv ◽  
Tingting Bao ◽  
Nan Zhou ◽  
Hong Peng ◽  
Xiangnian Huang ◽  
...  
Keyword(s):  
Parallel Computing ◽  
Control Mechanism ◽  
P Systems ◽  
Multiple Channels ◽  
Spiking Neural P Systems ◽  
Distributed Parallel Computing ◽  
New Variant ◽  
New Type ◽  
Turing Universality ◽  
Computing Models

This paper discusses a new variant of spiking neural P systems (in short, SNP systems), spiking neural P systems with extended channel rules (in short, SNP–ECR systems). SNP–ECR systems are a class of distributed parallel computing models. In SNP–ECR systems, a new type of spiking rule is introduced, called ECR. With an ECR, a neuron can send the different numbers of spikes to its subsequent neurons. Therefore, SNP–ECR systems can provide a stronger firing control mechanism compared with SNP systems and the variant with multiple channels. We discuss the Turing universality of SNP–ECR systems. It is proven that SNP–ECR systems as number generating/accepting devices are Turing universal. Moreover, we provide a small universal SNP–ECR system as function computing devices.

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