The power-saving opportunities of long-running application servers which execute on multi-core systems are studied in this paper. The research goal is to develop an efficient power-saving strategy of application servers with the minimum performance degradation in cloud environments. The power-saving strategy is based on the run-time information which is already available in a JVM, the base software component of application servers. Several key findings are revealed through this study. First, the particular behavior of application servers, also known as phases, can be related to the run-time information of a JVM. Thus the phases of an application server can be predicted before the applications actually execute on hardware. Secondly, some particular phases are observed in this study and used to establish the power-saving strategy, such as memory phases and execute phases. Finally, a new finding of idle phase is proposed to reduce significant energy wastage without performance degradations. Based on these findings, a set of power-saving algorithms is proposed and implemented with two widely used JVMs, Sun's Hotspot and Jikes RVM. With the experiments of five multi-threaded benchmarks and two web application benchmarks, the use of proposed power-saving strategy leads to the lowest value of energy-delay product among the other power-saving techniques, and the performance degradation is well below 6 percent.

With numerous connected devices and appliances, the smart home is one of the representative fields of Internet of Things (IoT). As the complexity of devices/appliances increase, numerous buttons (sometimes dozens) are designed on the remote controller in home spaces even if several of them are seldom used. A user may be confused with the controller even if he or she only intends to perform a simple operation. This confusion also leads to a higher probability of mal-operations. In addition, conventional methods of communication between remote controllers and connected devices, such as eXtensible Markup Language (XML) messages, are usually bandwidth-consumptive. To address these problems, an intelligent universal remote control system for home appliances named Point-n-Press is proposed. Point-n-Press addresses the directionality feature, which enables easy and intuitive control by pointing to the target device to display the target's control interface on the screen of the remote controller. By leveraging the state dependencies of home device/appliance operations, only functional buttons that are relevant to the current context are utilized. Two real prototypes are implemented to verify the feasibility of the proposed scheme. The evaluation results show that Point-n-Press is a useful and suitable control scheme for IoT-based smart homes.

The concept of smart homes (SH) has been extensively popularized, and there are a lot of technologies that need to be continuously utilized and integrated in such a concept. In this article, some applied problems of camera array (CA) in the SH are discussed and solved. Determining how to build an effective management method for CA in order to ensure that user privacy is not encroached upon is an important issue. In SH, the applications of CA are very diversified. We suggest that a satisfactory management method of CA should be based on the open service gateway initiative (OSGi) that includes resource management and monitoring (RMM) and UPnP security for the problems of resources and privacy, respectively. Finally, an applied example of CA is addressed in an elder-care center (EC). Simulation results show that the management strategy and application of CA based on an OSGi is satisfactory.

Abstract One of the most challenging issues in wireless sensor networks is to meet the requirements of coverage and connectivity under given energy constraints. Most existing coverage and connectivity algorithms work to form tree networks when sensor nodes do not have location information of themselves. However, a tree topology network does not perform well in terms of energy efficiency and scalability if compared with a cluster network. In this paper, a novel topology control algorithm called Adaptive Random Clustering (ARC) is proposed to form a cluster network with required coverage and connectivity without location information. The performance of its coverage intensity and connectivity is analyzed based on the characteristics of cluster topology, and their proper parameters are determined. ARC inherits an excellent energy efficiency from cluster topology and avoids the collisions and overhearing of data packets. A good scalability can be achieved as only a limited number of channels are needed in ARC for a large‐scale network. Furthermore, ARC can adjust the number of active nodes adaptively according to the required coverage to balance the energy consumption. Simulation results demonstrate that required coverage and connectivity can be satisfied and network lifetime is prolonged significantly. Copyright © 2010 John Wiley & Sons, Ltd.

The secure requirement of modern information systems is increasing significantly nowadays, especially in cloud computing with distributed applications. Among secure mechanisms of an organization, the access control (AC) is a foundation for modern information systems. In order to reach an effective and flexible approach of access control, the Role-based Access Control (RBAC) models are widely deployed in organizations. Comparing with traditional discretionary access control (DAC) and mandatory access control (MAC), the user-role-subject mapping of a RBAC model provides effective permissions assignments for access control of an organization. However, the RBAC sessions could be stretched over multiple distributed servers in cloud computing. The traversed sessions between servers could be modified, monitored and attacked by modern hacker techniques, and become secure leaks in RBAC models. In order to ensure secure sessions in cloud computing, various encryption approaches are used. Among these encryption approaches, the use of digital certificates by asymmetric encryption methods could be an appropriate solution to ensure the security of RBAC sessions. However, the cost of public/private keys management and issuing an appropriate certificate tokens for each member in organizations could be very expensive. The high cost might block the deployment of secure RBAC sessions, and then reduce the secure level of organizations. In order to improve this issue, a low-cost approach of secure sessions for RBAC models is proposed in this paper. The personal smart cards can be used as a certificate tokens in RBAC models to reach effective user authentications. Moreover, each session of RBAC models, including user-role-subject assignments and content-based accesses, can be protected by digital certificates which is generated by user own smart cards. Thus the security of RBAC sessions can be improved significantly. It is worth noting that personal smart cards are issued by public departments, thus the expense of tokens issuing and key management could be minimized. Therefore, the session security of a RBAC model could be ensured with user own smart cards without additional cost.

The performance and scalability issues of multithreaded Java programs on multicore systems are studied in this paper. First, we examine the performance scaling of benchmarks with various numbers of processor cores and application threads. Second, by correlating low-level hardware performance data to JVM threads and system components, the detail analyses of performance and scalability are presented, such as the hardware stall events and memory system latencies. Third, the usages of memory resource are detailed to observe the potential bottlenecks. Finally, the JVM tuning techniques are proposed to alleviate the bottlenecks, and improve the performance and scalability. Several key findings are revealed through this study. First, the lock contentions usually lead to a strong limitation of scalability. Second, in terms of memory access latencies, the most of memory stalls are produced by L2 cache misses and cache-to-cache transfers. Finally, the overhead of minor garbage collections could be an important factor of throughput reductions. Based on these findings, the appropriate Java Virtual Machine (JVM) tuning techniques are examined in this study. We observe that the use of a parallel garbage collector and an appropriate ratio of young to old generation can alleviate the overhead of minor collection and improve the efficiency of garbage collections. Moreover, the cache utilizations could be enhanced with the use of thread-local allocation buffer, and then leads to the performance improvements significantly.

Fault-based cryptanalysis has been developed to effectively break both private-key and public-key cryptosystems, making robust finite field multiplication a very important research topic in recent years. However, no robust normal basis multiplier has been proposed in the literature. Therefore, this investigation presents a semisystolic Gaussian normal basis multiplier. Based on the proposed Gaussian normal basis multiplier, both concurrent error detection and correction capabilities can be easily achieved using time redundancy technology with no hardware modification.

The conventional layered protocols in ad hoc networks tend to suffer from the inability to distinguish between losses due to route failures and congestion because of the inflexible structure. Recently, in efforts to overcome the challenges of dynamic environment, there have been increased interests in protocols that rely on interactions between different layers. The authors propose a cross-layer multicasting scheme based on the concept of local backtracking groups and adequate buffer equipped within nodes to avoid undesired retransmission from the source and further to improve the efficiency of source-to-receivers delivery with the aid of buffer. While encountering route failure, a node can quickly restore its routing paths to multicast subscribers by exploiting the precise notification from the MAC layer and the parent group then opportunely provides it with an unacknowledged packets conserved in the buffer. It is obviously benefic that retransmission packets are issued from the parent group rather than from the source. The authors present both analytic models and simulation results that substantiate the efficiency and robust of our approach based on realistic mobility scenarios.

In 2004, Jiang et al. presented a secure communication between set-top-box and smart card in DTV broadcasting. Their proposed protocol has following merits: security, dynamic session key, mutual authentication, lower computation and communication and users could freely chosen password. Moreover, the proposed scheme could prevent smart card clone and MacCormac Hack problems which are serious problems in DTV broadcasting. However, Jiang et al.'s scheme causes much computation and communication overhead of smart cards and STBs. In this paper, we propose an efficient secure communication between set-top box and smart card in DTV broadcasting. Our propose scheme not only has the same merits as that of Jiang et al.'s scheme but also significantly reduces the computation and communication cost. Therefore, our scheme only requires several hashing operations in both smart card side and STB side, and has a very small quantity of transmission data.

Abstract In recent years, the wireless network has been attracting a lot of attentions, and due to these devices has enjoyed a tremendous rise in popularity. However, the broadcast storm becomes a very serious problem for ad hoc networks to migrate into the overlay networks for the applications of group communications. The main concept of virtual subnet technology is the capability to group users into broadcast domains, which divides a virtual subnet into logic, instead of physical, segments and reduces the traffic overhead. With this characteristic, we propose an interoperability network model integrating self‐organizing ad hoc networks and the Internet/a conventional network with the partition of physical/virtual subnets. Moreover, we describe a protocol to establish the virtual broadcast domains by using the IPv6 addressing concept in ad hoc networks and perform IP‐based network communications in a multi‐switch backbone. Since the virtual subnet technology functions by logically segmenting the network into different broadcast domains, packets can only be delivered between fixed/mobile nodes with the same virtual identity. Therefore we can prevent the broadcast storm problem in MANET. The hierarchical networks, physical/virtual subnets, addressing method, and mobility management are described, and some performance issues are evaluated. Copyright © 2006 John Wiley & Sons, Ltd.

This paper proposes an approach in the object oriented concept to encrypt the object description information of MPEG-4 streams. It is a format-compliant algorithm with MPEG-4 streams. Without the proper key to decrypt, the decoder mistakenly interprets the object descriptors to construct the video object in the frame. It selectively chooses objects to encrypt, which reduces the volume of data to be encrypted, which make it simple and efficient

The paper focuses on the loop-level parallelism of bytecode on a distributed shared memory (DSM) system, which is built on a cluster of multiprocessors. We define a new attribute called 'Loop Attribute' to record the information of Java loops. When first loading a Java program, our Java virtual machine, called ES-JVM, checks and analyzes the loops of the bytecode dynamically, handles the data dependence of loops, and records the information as the loop attributes. ES-JVM uses the virtual shared memory and synchronization mechanisms provided by the DSM system to maintain the memory consistency. Before ES-JVM interprets the loops of the bytecodes, it dispatches the workload of loops to the interpreter threads at all nodes according to the loop attributes and the number of threads. After distributed and parallel execution of the loops, ES-JVM continues to interpret the rest of the bytecodes of the Java program. Finally, ES-JVM saves the loop attributes in a new class file for the next run. Our research shows that distributed and parallel execution of loops of a Java program could improve performance.

An intelligent moving agent (IMA) group designed for a mobile host (MH) is presented. The concept of group communication, intelligence and moving code are introduced into the design of the IMA. By the operation of the IMA group, a MH can act as a computer on the wired network and the following goals can be achieved: (1) the MH on the wireless network can become a member on the internet; (2) the hand-off problem can be solved by the moving feature of an IMA; (3) the location problem can also be solved by introducing the concept of group communication among the IMAs, which resides on different base stations, serving the same MH; and (4) the reliability and bandwidth of wireless communication can be solved by the store and forward ability of the IMA.