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1 – 10 of 11Xuhui Li, Zhiyong Peng and Jiannong Cao
Mobile agent, as a new mobile computing technology, has been applied to various parallel and distributed computing problem solutions. Several mobile agent systems have been built…
Abstract
Mobile agent, as a new mobile computing technology, has been applied to various parallel and distributed computing problem solutions. Several mobile agent systems have been built to drive the agents following a platform dependant scheme, and some formal approaches have been proposed to describe mobile agents’ behaviors or properties for respective purposes. However, there remains a lack of a standard approach to describing a mobile agent algorithm and its semantics from the viewpoint of a practical program, which makes it difficult to specify an algorithm unambiguously and verify its correctness formally. This paper proposes a practical approach to overcome that difficulty by defining a script language and associated mechanisms to specify and verify mobile agent algorithms. The language, called SMAL, can describe mobile agent’s behaviors clearly due to its explicitly defined semantics. Based on the semantics, a transformation function for converting the specified algorithm to its equivalent specification in Mobile UNITY, a well‐known mobile computation formal approach for correctness verification, is presented. Formal verification of the algorithms can be accomplished based on the UNITY‐logic rules.
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Ronnie Cheung, Gang Yao, Jiannong Cao and Alvin Chan
Context‐aware mobile computing extends the horizons of the conventional computing model to a ubiquitous computing environment that serves users at anytime, anywhere. To achieve…
Abstract
Purpose
Context‐aware mobile computing extends the horizons of the conventional computing model to a ubiquitous computing environment that serves users at anytime, anywhere. To achieve this, mobile applications need to adapt their behaviors to the changing context. The purpose of this paper is to present a generalized adaptive middleware infrastructure for context‐aware computing.
Design/methodology/approach
Owing to the vague nature of context and uncertainty in context aggregation for making adaptation decisions, the paper proposes a fuzzy‐based service adaptation model (FSAM) to improve the generality and effectiveness of service adaptation using fuzzy theory.
Findings
By the means of fuzzification of the context and measuring the fitness degree between the current context and the predefined optimal context, FSAM selects the most suitable policy to adopt for the most appropriate service. The paper evaluates the middleware together with the FSAM inference engine by using a Campus Assistant application.
Originality/value
The paper is of value in presenting a generalized adaptive middleware infrastructure for context‐aware computing and also comparing the performance of the fuzzy‐based solution with a conventional threshold‐based approach for context‐aware adaptation.
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Arjan Durresi, Leonard Barolli, Akio Koyama and Makoto Takizawa
Satellite networking will be an important component of future ubiquitous communications systems. Satellite networks will be especially useful to interconnect remote sensor…
Abstract
Purpose
Satellite networking will be an important component of future ubiquitous communications systems. Satellite networks will be especially useful to interconnect remote sensor networks. Therefore, satellite networks should provide the needed QoS, differentiation of services and at the same time keep the required scalability. The purpose of this paper is to propose a new Diffserv‐based scheme of bandwidth allocation during congestion, called proportional allocation of bandwidth (PAB).
Design/methodology/approach
The paper suggests a method for implementing PAB without storing per‐flow state, which makes the scheme scalable and simple and shows, by simulation, the advantages of using PAB in IP satellite networks.
Findings
The paper finds that PAB can be used in geostationary earth orbit, MEO and low earth orbit satellite networks. In PAB, during congestion all flows get a share of IP available bandwidth, which is in proportion to their subscribed information rate.
Originality/value
The simulations described in this paper show that the performance of PAB scheme is good on congested satellite networks.
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Hideyuki Takahashi, Kazuhiro Yamanaka, Satoru Izumi, Yoshikazu Tokairin, Takuo Suganuma and Norio Shiratori
Real‐time multimedia supervisory systems generally include a distributed system that delivers live video input captured with cameras at the watched person's site, using a PC or…
Abstract
Purpose
Real‐time multimedia supervisory systems generally include a distributed system that delivers live video input captured with cameras at the watched person's site, using a PC or hand‐held device at the distant supervisor's site. The system comprises many entities such as cameras for image capture, transmission software, network connections, receiver software, a display device, multimedia processing software and hardware, control software, etc. The purpose of this paper is to realize a safe and convenient supervisory system that autonomously provides users with services that fulfill users' requirements related to quality and privacy in a ubiquitous information environment.
Design/methodology/approach
A system is designed by integrating environmental information acquired from the real world and knowledge related to human social activities. A real space understanding mechanism is proposed to infer the situations and relationships of users by combining sensing information and social knowledge. Social knowledge related to human relationships, the life style of the watched person, home structure, etc. is used with ontology to infer the situations of users.
Findings
An early prototype was implemented for supervising elderly people and some experiments were performed based on several scenarios. Results obtained from some experiments confirmed that this supervisory system can provide real‐time multimedia supervisory services for elderly people, with reasonable quality‐of‐service and privacy that meet the users' requirements.
Originality/value
The system described in this paper assesses the situation of users and surrounding environmental information to provide appropriate supervisory services. This paper provides insight into the design and development of ubiquitous application systems to realize comfortable and safe services using a combination of environmental information and social knowledge.
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Kaoru Hiramatsu, Takashi Hattori, Tatsumi Yamada and Takeshi Okadome
The purpose of this paper is to focus on sensor data fluctuations. Context‐aware applications in the real world adapt their behavior to contexts abstracted from real‐world…
Abstract
Purpose
The purpose of this paper is to focus on sensor data fluctuations. Context‐aware applications in the real world adapt their behavior to contexts abstracted from real‐world situations sensed as physical quantities by heterogeneous and distributed sensors. Most of the adaptations are programmed as rules derived from human experience in making environments comfortable and efficient. Preparation of sufficient rules, however, is difficult because oversights and exceptional contexts are inevitable.
Design/methodology/approach
This paper, focuses on sensor data fluctuations and calculates the probabilities indicating the frequency of such fluctuations.
Findings
The results help to confirm the preset rules of the context‐aware applications and find previously unnoticed situations that the context‐aware applications should cope with.
Originality/value
The paper shows how this method is applied to log data captured in an office in order to evaluate the method's capabilities and consider the feasibility of abstracting the newly observed situations into rules.
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Chao Sha, Ruchuan Wang, Haiping Huang and Lijuan Sun
Energy consumption is a fundamental concern in wireless multimedia sensor networks, even more than that in traditional wireless sensor networks. In fact, sensors are…
Abstract
Purpose
Energy consumption is a fundamental concern in wireless multimedia sensor networks, even more than that in traditional wireless sensor networks. In fact, sensors are battery‐constrained devices, while multimedia applications, which require higher transmission rates and more extensive processing capacity, produce large quantities of data. The purpose of this paper is to propose a method which could save multimedia nodes' energy during their sleeping and transmitting phases and effectively bring down energy consumption.
Design/methodology/approach
Based on the location and direction angle of nodes, areas of the overlapping sensing region between adjacent nodes could be calculated and a sleeping strategy is carried out to reduce energy consumption of inactive nodes. Moreover, an improved image comparison and block transmission methods by utilizing the sequence similar detection arithmetic theory is brought up as well to further save the node's energy.
Findings
With the help of the mobile nodes and by dividing the network into grids, sensing direction of multimedia node as well as the area of the overlapping sensing region could be obtained which provide a basis for the sleeping strategy. Furthermore, energy consumption on transmission is also reduced by only transmitting the unmatched blocks. Simulation results show that this method obtains satisfactory performance on prolonging the networks' lifetime.
Originality/value
This paper is of value in presenting an effective energy‐saving strategy for wireless multimedia sensor networks.
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Elhadi Shakshuki and Abdur Rafey Matin
Intelligent agents are becoming an essential part of collaborative virtual environments. The purpose of this paper is to present an architecture of a learning agent that is able…
Abstract
Purpose
Intelligent agents are becoming an essential part of collaborative virtual environments. The purpose of this paper is to present an architecture of a learning agent that is able to utilize machine learning techniques to monitor the user's actions.
Design/methodology/approach
A learning agent is developed and integrated into federated collaborative virtual workspace.
Findings
The experimental results showed that the combination of genetic algorithms and reinforcement learning algorithms provides the agent with better learning capability resulting in better predictions for the user.
Originality/value
This paper provides experimental results and a performance analysis in terms of accuracy of predictions, processing time, and memory utilization of the agent.
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Akiko Takahashi and Tetsuo Kinoshita
With the wide spread of the ubiquitous environment, it is necessary to provide adequate multimedia communication services for various users under various networked environments…
Abstract
Purpose
With the wide spread of the ubiquitous environment, it is necessary to provide adequate multimedia communication services for various users under various networked environments. In such situations, it is essential to organize multimedia software components dynamically to provide necessary services for effective service provision based on the system's operational environment during the run time of the system. The purpose of this paper is to propose a new scheme for observing and controlling behavior of the QoS‐aware agent organization, which provides a flexible QoS control of multimedia service components.
Design/methodology/approach
Two models are proposed in this paper: a flexible distributed system (FDS) model and a behavioral characteristics model (BCM), which were applied to the design of network middleware constructed as a QoS‐aware agent organization. Experiments were performed using the middleware prototype system.
Findings
Results confirmed that the proposed models provide an effective scheme for designers of multimedia communication services.
Originality/value
This paper shows that using the FDS model, a multiagent system can be designed and constructed systematically. In addition, using BCM, a multiagent system with flexible QoS control capability can deal with changes of the system's operational situations and thereby maintain the required QoS as well as its behavioral characteristics.
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Zhaohui Wu, Hong Li, Guoqing Yang, Zhigang Gao and Pan Lv
The purpose of this paper is to focus on the method to improve real‐time property of real‐time operating system (RTOS), one of the most essential problems in RTOS studies.
Abstract
Purpose
The purpose of this paper is to focus on the method to improve real‐time property of real‐time operating system (RTOS), one of the most essential problems in RTOS studies.
Design/methodology/approach
Improved task models are proposed based on the basic task and extended task models of OSEK operating system (OSEK OS). According to different task states, optimized scheduling algorithm was put forward. Some examples in a practical environment are described that illustrate the value of the method.
Findings
This method has been successfully implemented and evaluated in an OSEK compatible operating system, SmartOSEK OS. The time cost of context switching is decreased and the efficiency is enhanced.
Research limitations/implications
The improvement gained depends on the ratio of each strategy applied. In case the strategy D is applied too many times, the performance will be lead to a depressing result. For real‐time system, a long‐lived process that maybe increase the ratio of strategy D is not the optimal selection.
Originality/value
Dividing the ready state of task into intermediate state and initial state, can optimize the process of task context switching for OSEK OS. The method has proven to be useful in improving the real‐time property of RTOS.
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