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Low-energy background through Compton scattering from the ambient $\gamma$ rays can be contaminated in direct dark matter search experiments. In this paper, we report comparable measurements on low-energy spectra via Compton scattering from several $\gamma$-ray sources with a p-type point-contact germanium detector. The spectra between 500 eV and 18 keV have been measured and analyzed. Moreover, the features of the electron binding effect, particularly at the edges of the K- and L-shells in the germanium atom, were observed with different gamma sources and were consistent with the models in the Geant4 simulation. An empirical background model is proposed that provides insights into understanding the low-energy background in germanium for direct dark matter experiments., Comment: 7 pages, 5 figures and 2 tables; version accepted by JINST

A model of the Li-diffused inactive layer in P-type high purity germanium detectors is built to describe the transportation of charge carriers and calculate the charge collection efficiency therein. The model is applied to calculate charge collection efficiency of a P-type point-contact germanium detector used in rare event physics experiments and validated in another P-type semi-planar germanium detector. The calculated charge collection efficiency curves are well consistent with measurements for both detectors. Effects of the Li doping processes on the charge collection efficiency are discussed based on the model. This model can be easily extended to other P-type germanium detectors, for instance, the P-type broad-energy Ge detector, and the P-type inverted-coaxial point-contact detector.

Image compression, as one of the key-enabling technologies in multimedia communications, has been paid much attention in the past decades, where the two key techniques discrete wavelet transform (DWT) and set-partitioning in hierarchical trees (SPIHT) have great influence on its final performance. Due to the proprieties of fast computation, low memory requirement, DWT has been adopted as a new technical standard for still image compression. But it did not make much use of the region information. Although several improved methods have been proposed that adopt direction-adaptive wavelet for using the geometric and spatial information, they still did not consider the texture information. Furthermore, the traditional SPIHT algorithm has the drawbacks of long bits output and time consuming. In this paper, we first propose a new technique named interpolation-based direction-adaptive lifting DWT. It can adaptively choose the best lifting direction and use the Lagrange interpolation technique to make prediction according to its local characteristics. This method makes good use of the image texture features. Then a modified SPIHT coding algorithm is presented. It improves the scanning process and can effectively reduce the coding bits length and running time. Experimental results demonstrate that our method can yield better results than traditional techniques.

A new gel polymer electrolyte (GPE), fumed silica-doped poly(butyl methacrylate-styrene) (P(BMA-St))-based gel polymer electrolyte, was developed for lithium ion battery. The copolymer P(BMA-St) was synthesized by emulsion polymerization, the copolymer membranes doped with and without fumed silica were prepared through phase inversion, and the GPEs were obtained by immersing the membranes in 1 M LiPF6 solution. The structure and performances of the copolymer, the membranes and the GPEs were characterized by Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), scanning electron spectroscopy (SEM), thermogravimetric analysis (TGA), linear sweep voltammetry (LSV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). The copolymer P(BMA-St) is formed through the breaking of the double bond C C in the monomers, butyl methacrylate and styrene. By doping 10 wt.% fumed silica in P(BMA-St) membrane, the properties of the membrane and the corresponding GPE were improved. The membrane doped with fumed silica is stable up to 355 °C and its pore size becomes more uniform and smaller; oxidative decomposition potential of the GPE doped with fumed silica is raised to 5.2 V (vs. Li/Li+) and its ionic conductivity is as high as 2.15 × 10−3 S cm−1 at ambient temperature.

Due to the latest developments in communication and computing, smart services and applications are being deployed for various applications such as entertainment, health care, smart homes, security and surveillance. In intelligent communication environments, the main difficulty arising in designing an efficient congestion control scheme lies in the large propagation delay in data transfer which usually leads to a mismatch between the network resources and the amount of admitted traffic. To attack this problem, this paper describes a novel congestion control scheme in intelligent communication environments, which is based on a Back Propagation (BP) neural network technique. We consider a general computer communication model with multiple sources and one destination node. The dynamic buffer occupancy of the bottleneck node is predicted and controlled by using a BP neural network. The controlled best-effort traffic of the sources uses the bandwidth, which is left over by the guaranteed traffic. This control mechanism is shown to be able to avoid network congestion efficiently and to optimize the transfer performance both by the theoretic analyzing procedures and by the simulation studies.

We report femtosecond laser induced valence state and refractive index change in transparent Sin(3+)-doped fluoroaluminate glass. The effect of annealing on the induced changes was studied and the thermal stability of these changes was discussed. The results show that the femtosecond laser induced valence state change is more stable than the induced refractive index change. The observed phenomenon could be applied to design the thermally erasable or stable storage medium. (c) 2007 Elsevier B.V. All rights reserved.

A detailed numerical modelling study was carried out to represent geotechnical aspects of the Wieczorek underground coal gasification (UCG) site in Poland. A coupled thermos-mechanical numerical model was created to represent a single coal burning panel. The coal burning process was simulated by modifying the energy balance equation with an additional term related to the calorific value of coal as a source. Temperature dependent material properties were assigned to the coupled thermal-mechanical model according to published data. In the model, the burning zone spread about 7.5m laterally after 20 days of burning. Results from the coupled model were used to gauge a worst-case scenario in terms of the potential size of a formed cavity. This data was used within a less computationally expensive mechanical-only numerical model in order to evaluate the ground subsidence caused by the worst-case scenario for single and multiple UCG burning panels. The single panel burning resulted in 23mm of ground subsidence at the top of the model after long term coal burning. The ground subsidence measured at the top of the model, at the center point of the gasification arrangement, was approximately 72mm when five panels were burnt with an edge to edge panel distance of 5m; this was increased to 85mm for seven panels. The numerical modelling results have implications to the industrial application of UCG. Keywords: Numerical model, underground coal gasification, calorific value, subsidence.

Two serials of Eu3+ doped AlN films are prepared by means of magnetron RF reactive sputtering under different RF powers and N-2/(N-2 + Ar) ratios. XRD analysis indicates that the films change from amorphous to c-axis oriented crystalline as the RF power increases or as the N-2/(N-2 + Ar) ratio decreases. Lower N-2/(N-2 + Ar) ratio and higher RF power enhance the deposition rate and crystallinity. The grain size and surface roughness observed by SEM and AFM increase with the increase of the RF power. The emission from 5 Do to F-7(J) (J = 0-4) of Eu3+ is observed in the PL spectra for all the crystalline films, and the D-5(0) to F-7(2) transition of the films grown at 300 W has double exponential decays, 38 and 161 mu s. The crystalline quality of the films improves the photoluminescence intensity. (C) 2005 Elsevier B.V. All rights reserved.

The compound FeSr(2)NdCu(2)O(7+delta) (Fe1212) was successfully synthesized by solid-state reaction. X-ray diffraction data indicate that the sample is of single phase. Rietveld whole-pattern-fitting method was used to refine the crystal structure of samples prepared under different annealing conditions using the tetragonal system with space group P4/mmm. Magnetization measurements indicate that magnetic susceptibility chi changes with temperature in a Curie-type manner. Resistance measurements indicate that these samples have a semiconductor-like behavior.

Ln(3+) (Ln = Nd, Sm, Eu, Gd, Dy, Ho, Er)-doped Y3GaO6 compounds were prepared by solid-state reaction, and their optical spectra such as absorption, photoluminescence, excitation and time-resolved spectra have been measured for Ln Nd, Sm, Dy, Ho, Er. X-ray powder diffraction shows that the lattice parameters of the compounds (Y(0.96)Ln(0.04))(3)GaO6 decrease with the decrease of the radii of trivalent Ln(3+) ions, indicating that Ln(3+) ions have substituted for y(3+) ions in the lattice. Optical spectra show that there are obvious absorptions at ultraviolet to visible region. The strong emissions in visible and infra-red region show that Y3GaO6 is a suitable host for rare-earth-doped laser crystal and phosphor materials. (C) 2004 Elsevier B.V. All rights reserved.

Pr1+xBa2−xCu3O7±δ solid solution was investigated by means of X-ray powder diffraction and Rietveld analysis. Single-phase PrBa2Cu3O7±δ (Pr123) can be synthesized under a Pr-rich condition by sintering at 950 °C in air. The solubility of Pr1+xBa2−xCu3O7±δ solid solution is 0.08≤x≤0.80. The structure of Pr1+xBa2−xCu3O7±δ is orthorhombic for 0.08≤xx≤0.80. To form single-phase Pr123, the Ba sites in the Pr123 structure are partially occupied by excess Pr ions, and the smallest amount of excess Pr is x=0.08. Meanwhile, all Ba ions stay in the Ba sites.

The crystal structures of a series of compounds with the composition Ln(3)GaO(6)(Ln = Nd, Sm, Eu, Gd, Tb, Dy, Ho and Er) synthesized by solid-state reaction at 1400degreesC are investigated. X-ray diffraction shows that Ln3GaO6 has a non-centro symmetric orthorhombic structure (space group Cmc2(1)). Lattice parameters a, b, c and cell volume and the average distances between Ln(l)-O, Ln(2)-O of these compounds decrease with the decreasing of the radii of trivalent Ln ions, which accord with the expected lanthanide contraction behavior. There are two sites of seven-fold coordination for Ln atoms with oxygens, and Ga atoms are in oxygen tetrahedra which are distorted and elongated along the a-axis. Magnetization measurements indicate that the susceptibility X changes with temperature in Curie-type manner. (C) 2004 Elsevier Inc. All rights reserved.

We have investigated the structure and magnetic properties of Pr 1− δ (Co,Cu) 5+2 δ (0 δ 7 -type structure, using X-ray powder diffraction and magnetic measurements. The lattice parameters ( a and c ) of Pr 1− δ (Co,Cu) 5+2 δ compounds increase with increasing Cu content since the radius of Cu is a little larger than that of Co. Our experimental results indicate that Cu may stabilize Pr 1− δ (Co,Cu) 5+2 δ compounds with the TbCu 7 -type structure, but δ is only determined by the temperature. The X-ray patterns of magnetically aligned samples show that the compounds with x =2.0 and 3.0 exhibit easy-plane magnetocrystalline anisotropy. The saturation magnetization and Curie temperature decrease with increasing Cu content.

The PrBa(2-x)Sr(x)Cu(3)O(7+/-delta) solid solution was investigated by means of X-ray powder diffraction in combination with Rietveld analysis. The Sr-doped Pr123 single phase could be synthesized at 950degreesC in air. The solubility of PrBa(2-x)Sr(x)Cu(3)O(7+/-delta) solid solution is 0.2 less than or equal to x less than or equal to 0.6. The structure of PrBa(2-x)Sr(x)Cu(3)O(7+/-delta) is orthorhombic for x = 0.2. The structure transforms into tetragonal for 0.3 less than or equal to x less than or equal to 0.6. In the PrBa(2-x)Sr(x)Cu(3)O(7+/-delta) structure, Sr ions can replace Ba ions, the highest value is x = 0.6 under our experimental condition. But Sr ions could not replace Pr ions. Furthermore Pr ions could not occupy the sites of Ba ions in the PrBa(2-x)Sr(x)Cu(3)O(7+/-delta) system. Both ionic radii and chemical properties play an important role in the mutual substitution of Pr, Ba and Sr ions in the Pr123 structure of the PrBa(2-x)Sr(x)Cu(3)O(7+/-delta) system. (C) 2003 Elsevier B.V. All rights reserved.

The coexistence of superconductivity and magnetic order seems to take place in the so-called ruthenate-cuprates (Ru-1212). A systematic study is carried out on crystal structure of the RuSr 2 R Cu 2 O 8− δ phases ( R =Gd, Tb, Dy, Y, Ho, Er) synthesized under high pressure by X-ray powder diffraction. RuSr 2 R Cu 2 O 8− δ ( R =Gd, Tb, Dy, Y, Ho, Er) has the Ru-1212-type structure of a tetragonal symmetry and the RuO 6 octahedra rotate around the c -axis with an additional small rotation around an axis perpendicular to c . The DC-magnetization data establish that compounds with R =Gd, Y, Ho, Er exhibit ferromagnetic order below about 140 K, and the Meissner effect was observed at low temperature for R =Y compound.

The Pr1+xBa2-xCu3O7±δ solid solution was investigated by means of X-ray powder diffraction combined with Rietveld analysis. A Pr123 single phase could be synthesized under Pr-rich conditions by sintering at 950 °C in air. The solubility range of Pr1+xBa2-xCu3O7±δ solid solution is 0.08≤x≤0.80. The structure of Pr1+xBa2-xCu3O7±δ for 0.08≤x

Subsolidus phase relations of the constant copper oxide content (50 mol%) section in the PrO(11/6)-BaO-CaO-CuO system at 950 degreesC in air are investigated by means of X-ray diffraction analyses. The phase relations consist of I single-phase region, I two-phase region, 2 three-phase regions and 6 four-phase regions. Mutual substitutions among Pr, Ba and Ca in the Pr123 structure were studied in detail. The result indicates that Ba ions can be replaced exclusively by Pr ions, but not by Ca ions, whereas Ca ions can partially occupy the sites of Pr ions. The ionic radius plays a more important role than the chemical property for substitution among Pr, Ba and Ca ions in the Pr123 structure. (C) 2003 Elsevier B.V. All fights reserved.

The techniques of scanning force microscopy have been successfully used to investigate characterization of the surface structure of polymer films. We obtained AFM/STM images of polyaniline films with molecular resolution. The repeat unit consists of alternating phenyl rings (nitrogen atoms) in polyaniline molecular chains. The results clearly showed characteristic structure in polyaniline films. The molecular chains are separated by dopants with different sizes in the polyaniline films. The distance between molecular chains depends upon the size and geometric shape of dopants, the surface structure of polyaniline films were obviously observed to be also influenced.

Along with the increase in users' demands for service functions, single services or simple functions cannot satisfy users' requirements any more. Therefore, we need service composition to provide customized services or compound functions to meet users' needs. However, existing methods cannot describe customized services or guarantee the safety of service composition, so we propose a novel framework for service description and operations in this paper. Our framework is composed of a new format for service description and a set of service operations. The former is used to describe the structure of customized services and to be the foundation of service operations, while the latter is used to represents the dependency relationships between services and to verify the safety of service composition. Compared to the existing service description languages, our method can be used to describe customized services and to be the basis for achieving the automation of service composition. An example is given to demonstrate that our approach can provide better service description and safe service composition.

Personalized recommendation techniques play more and more important roles for the explosively increasing of information nowadays. As a most popular recommendation approach, collaborative filtering (CF) obtains great success in practice. To overcome the inherent problems of CF, such as sparsity and scalability, we proposed a semantic based mixture CF in this paper. Our approach decomposes the original vector into semantic component and residual component, and then combines them together to implement recommendation. The semantic component can be extracted by topic model analysis and the residual component can be approximated by top values selected from the original vector respectively. Compared to the traditional CF, the proposed mixture approach has introduced semantic information and reduced dimensions without serious information missing owe to the complement of residual error. Experimental evaluation demonstrates that our approach can indeed provide better recommendations in both accuracy and efficiency.

GPUTA 2009 contains 3 peer-reviewed papers selected by members of the GPUTA 2009 Program Committee. The workshop covers some major topics in the field of GPU applications in parallel processing, high-performance computing, and scientific and engineering computing. We thank the authors for submitting their work and the members of the GPUTA 2009 Program Committee for managing the reviews of the workshop papers.

A time-delay estimate algorithm for Internet-based control systems using the least mean square (LMS) filter algorithm was proposed. Modeling the time delay of Internet-based control systems as a nonlinear time series, the future time delay could be predicted by LMS algorithm. The simulation results showed that the proportion of time-delay prediction values, with prediction error of less 5%, reached 81.7% and the LMS algorithm can achieve ideal efficacy if time-delay has no variety abnormally. Based on the estimation time-delay online, an adaptive time-delay compensator was designed. An Internet-based water tank control system was used to demonstrate the validity of the designed time-delay compensator. The experimental results illustrated that the time-delay compensator can improve dynamic performance of the control system markedly.

In a transparent computing environment, clients load their Operating Systems (OSes) from a remote central server, thus the boot time of clients is a significant performance metric for customers. With the rapid evolution of systems based on transparent computing, an in-depth study on the performance of the booting process in it is urgently required. This paper studies the boot performance of clients in a transparent computing environment for a workload associated with the booting process of clients. To address the performance issues, we propose and solve a closed queuing network model, which is employed to evaluate and predict the boot performance of the system with various hardware configurations, using the obtained workload characteristics. The results from the model are consonant with the actual results measured in our experiments. And then we employ the model to predict and analyze the boot performance.

With the success of wireless technologies in consumer electronics, standard wireless technologies are envisioned to be deployed in industrial environments as well. Many industrial applications have stringent requirements on reliability and timing. In wired environments, reliability is well catered by field-bus systems. When wireless links are adopted, reliability requirement is significantly more difficult to be fulfilled due to the adverse properties of the radio channels. In this paper, a novel reliable routing protocol for industrial wireless networks is proposed. Based on the idea of cross-layer design, a new layer (CBF_A) is inserted between MAC layer and network layer, which can provide the information of link quality to network layer. Our experiments prove that the new protocol is superior in both cost and reliability.

The recently proposed active queue management (AQM) is an effective method used in Internet routers for congestion control, and to achieve a tradeoff between link utilization and delay. The de facto standard, the random early detection (RED) AQM scheme, and most of its variants use average queue length as a congestion indicator to trigger packet dropping. In this paper, we propose a novel proportional and differential RED algorithm, called NPDRED, as an extension of RED. NPD-RED is based on a self-tuning proportional and differential controller, which not only considers the instantaneous queue length at the current time point, but also takes into consideration the ratio of the current differential error signal to the buffer size. Furthermore, we give theoretical analysis of the system stability and give guidelines for the selection of feedback gains for the TCP/RED system to stabilize the instantaneous queue length at a desirable level. Extensive simulations have been conducted with ns2. The simulation results have demonstrated that the proposed NPD-RED algorithm outperforms the existing AQM schemes in terms of average queue length,average throughput, and stability.

The applications of 3D information acquisition and 3D solid surface reconstruction are increasing in the last years. This paper presents a solution of capturing 3D information from 2D image sequence, which captures 3D information with a rotated camera. Solutions for 3D information acquisition are briefly reviewed first, and current work on 3D information acquisition from 2D image sequence is described. We consider 3D points acquisition, and describe the result based on graph-cutted by horizontal tangents from several different viewpoints. The results are many compound and smooth curves, and multi-slices, which can be used to reconstruct the solid surface. The algorithm is suitable for protuberant solid reconstruction especially.

This article describes a new method which we have used for computing matrix-vector products. Matrix-vector multiplication is the core of black-box algorithm, which is effective when we analyze the properties of sparse or structured matrix. Hence it is very useful to optimize the calculation. Here we design an algorithm for large-sized sparse zero-one matrix-vector products based on the theory of cache, whose advantage is that it can reduce cache misses to the minimum. We divide the matrix M into several vertical strips and vector x is stripped by system in the corresponding way. Then we calculate the products of all stripped matrix and the vector, and add all the results together to obtain the Zo matrix-vector product. We use C++ language to implement the algorithm in Windows XP and have experiments to compare the time costs between the Zo and stripped matrix-vector products of various blocking schemes. After many experiments, we find the most appropriate blocking scheme to suit the cache size.

The advent of Internet and WWW imposes great challenges to search information quickly and accurately. Intelligent search has become a hot topic in Internet computing, with rival search engines battling to become the de facto Web portal. Web search becomes more and more personalized and this requires that the search agent has some "intelligent" to satisfy specific requirements of different users. This paper reports a fuzzy intelligent search agent and shows its great advantages. A detail example has been given to illustrate the pros and cons of the fuzzy approach. Based on our fuzzy intelligent search agent, the efficiency of search has been greatly improved and it will be a practical solution for intelligent information retrieval.

Recent researches on parallel and distributed systems present drawbacks and limitations regarding to the analysis, design, implementation and execution of high performance parallel applications. Complex issues related to the development of such high performance parallel applications vary from the modularization, in the design stage, to the task allocation and distribution. Such difficulties have motivated the design and implementation of MidHPC (middleware for high performance computing), a middleware which automatically and transparently balances process workloads using knowledge obtained from techniques to extract and predict application behaviors. Through this middleware, application tasks transparently communicate among each other through a distributed shared memory system. In order to better take advantage of the MidHPC middleware, parallel applications are written using the POSIX threads standard. Applications developed following this programming model can be executed in SMPs, clusters and grids without any source code modification nor any additional change. Experimental evaluation of the proposed middleware shows not only good scalability and performance can be achieved, as also efficient process migration.

The metadata in the Semantic Grid are described using the technologies of the Semantic Web, such as OWL (OWL Web Ontology Language), and SPARQL has been recommended by W3C. And most metadata including actual data are stored in relational databases. Under such a situation, the necessity of SPARQL-to-SQL translation algorithm development becomes issued for seamless data access to the Semantic Grid data. Even though several translation algorithms have been proposed, there still remain the following problems, and especially these algorithms are dependent on a specific storage model. Hence, when we try to use one of other storages not the original, much cost is required to modify and verify the translation algorithm. In this paper, we propose a new system model to independently use an algorithm upon storage structures. The system model guarantees independency between translation algorithms and storages, and thus it improves application and usability of translation algorithms.

The control and coordination of mobile robots in groups that can freely cooperate and move on a plane is a widely studied topic in distributed robotics. In this paper, we focus on the flocking problem: there are two kinds of robots: the leader robot and the follower robots. The follower robots are required to follow the leader robot wherever it goes (following), while keeping a formation they are given in input (flocking). A novel scheme is proposed based on the relative motion theory. Extensive theoretical analysis and simulation results demonstrate that this scheme provides the follower robots an efficient method to follow the leader as soon as possible with the shortest path. Furthermore, this scheme is scalable, and the processing load for every robot is not increased with the addition of more robots.

The concept of Churn is the continuous process of node arrival and departure in distributed peer-to-peer network. There exists two eprotocol Selecting News and Eldersxtreme cases. The first one is that enormous nodes joining the system concurrently, which results in a flash crowd scenario for special nodes in the system. The other is that enormous nodes crashed or the connections between nodes are failed in a moment, which comes out a shrink search later. In this paper, we present a novel protocol Selecting News and Elders (SNE) with positive communication policy among peers and conservative neighbor maintenance scheme under churn, to keep desirable properties such as a low network diameter and clustering. The protocol is resilient against different churn and fit for P2P information dissemination and file sharing systems especially.

In this paper we have considered the distributed scheduling problem for channel access in wireless mesh networks. The problem is to assign time-slots for each node in the network to access the control channels so that it is guaranteed that each node can broadcast the control packet to any one-hop neighbor in one scheduling cycle. The objective is to minimize the total number of different time-slots in the scheduling cycle. In the single-channel ad hoc networks, the known best result for this problem is proved to be (K2 + 1) in arbitrary graphs and 25K in unit disk graphs with K as the maximum node degree. The original contributions of this paper are that it has taken the large interference range problem into consideration for the first time and proposed two algorithms for the scheduling problem, namely, the one neighbor per cycle (ONPC) algorithm and the all neighbors per cycle (ANPC) algorithm. We prove that the number of time-slots by the second algorithm is upper-bounded by 2K in some special case. The fully distributed versions of these algorithms are given in this paper. Simulation results also show that the performance of ANPC is rather better than ONPC.

This paper establishes ACE system that supports active emergency call service. ACE system is physically composed of E-device (emergency mobile device) for the handicapped, single elderly, and children, and E-server (emergency server) with realtime monitoring management feature. E-device reports emergency situation to emergency institutions and the user's guardian through Internet or CDMA. Therefore, E-device is devised to be affordable, light- weighted, and small enough for the minorities including the handicapped, the elders, and children could carry around. E-server is developed as a comprehensive control system which provides realtime monitoring feature in order to manage E-devices efficiently and guarantee quality service.

In this paper, SeviceCuts, a decision tree based model is proposed, considering the special attributes of wireless service and the normal need of users, helping service decision agent classify the wireless services adaptively. The decision tree is traversed based on some searching rule. A small number of matching rules are stored in the leaf node, which contain the most matching service strategies to users, and are linearly traversed to find the highest priority rule that matches the user's query requirement. The analysis of algorithm complication and performance shows that the efficiency of ServiceCuts decision tree model is better than traditional linear search structure and the normal binary decision tree structure.

The Internet evolution has been requiring the development of new technology to support multimedia transmission such as images, database access, audio and video in realtime. Such development needs new services and supports like the voice over IP (VoIP) which has a main motivation in the low cost communication and management. VoIP systems have motivated this work which proposes an adaptive audio quantizer named IQ (intervalar quantizer) to reduce the data dimensionality and consequently the entropy, what allows better audio compression. This quantizer is adaptive because it has an error tolerance parameter which can be varied according to the available network bandwidth, allowing to adapt communication. After transmitting, the audio is improved by using a filter with complex poles in the Z plan. This filter attenuates non-important frequencies, privileging the sensitive ones to human audition. Results confirm that IQ and the filter offer good quality (measured using the mean opinion score metrics) and compress ratio.

Mobility especially the flexibility given to us by the mobile phone is the future of computing as we know it. No longer are we restricted to sitting at a desk in front of a powerful desktop machine. Mobile technology of today allows users to work, learn and play no matter where they may be. Wireless technology is becoming more and more a standard feature of computing, so much so that it is expected that approximately two billion Bluetooth enabled devices will have been produced by the end of 2007. This paper examines how Bluetooth application development may be simplified for the programmer by use of the mobile message passing interface (MMPI). It explores a selection of application areas that can benefit from this simplified means of wireless inter-device communication, including: compute intensive tasks, mobile learning and multi-player gaming.

This paper presents the MidHPC project (standing for middleware for high performance computing project), which aims at providing support to the execution of multithreaded applications on heterogeneous environments, such as Grids. MidHPC is composed of three main modules: an extractor, a load balancer and a distributed shared memory. Basically, it automatically converts threads into processes, and optimally (by using application and environment knowledge) distributes them on grids, through migrations, by using a transparent support for process communication over networks.

It is estimated that by the end of 2007 approximately two billion Bluetooth enabled devices will have been produced to date. The mobile phone market has a significant share of this. The gaming sector has done little to promote the use of bluetooth for gaming. This reflects the limited number of bluetooth enabled games currently available. Why should the modern day phone user have to compete only against the device, when a far more competitive, and enjoyable game can be achieved by the interaction of two or more human players. The development of such games, typically requires significant bluetooth specific api calls to setup the communications mechanism, and carry out communication. This paper details how the Mobile Message Passing Interface (MMPI) may be applied the the realm of bluetooth gaming. In particular this paper introduces a framework that allows for the transformation of a single player game, to a multiplayer Bluetooth enabled game with the minimum of code changes.

As a fundamental component in wireless networks, location management consists of two operations: location update and paging. These two supplementary operations enable the mobile user ubiquitous mobility. However, in case of failed location update, a significant consequence is the obsolete location identity in the network databases and thereafter the incapability in establishing the valid route for the potential call connection, which will seriously degrade the network quality-of-service (QoS). This issue is not theoretically studied in the literature. In this paper, we perform a quantitative analysis of the location management effect on QoS in the wireless networks. The metrics call blocking probability and the average number of blocked calls are introduced to reflect the QoS. For the sake of general applicability, the performance metrics are formulated with the relaxed tele-traffic parameters. Namely, the call inter-arrival time, cell residence time, location area residence time and location update inter-arrival time follow a general probability density function. The formulae are additionally specified in the static and several dynamic location management mechanisms. Numerical examples are presented to show the interaction between the performance metrics and location management schemes. The discussions on the sensitivity of tele-parameters are also given.

Motivated by the first process allocation limitations of the original Route load balancing algorithm, this paper presents RouteGA (Route with Genetic Algorithm support) which considers historical information about parallel application executions in order to optimize the first scheduling. This information is extracted by using monitors and summarized in a knowledge base used to quantify process occupation at the launch moment. Such occupation is used to parameterize a genetic algorithm responsible for optimizing the process allocation on heterogeneous computing environments such as Grids. Results confirm RouteGA over- performs the original Route, which had previously overper-formed others from literature.

Sensor networking has emerged as a promising tool for monitoring and actuating the devices of the physical world, employing self-organizing networks of battery-powered wireless sensors that can sense, process, and communicate. Though many specific technical challenges remain and deserve much further study, the primary factor currently limiting progress in sensor networks is not these challenges but is instead the lack of an overall sensor network architecture. In this paper, we characterize the unique design requirements of sensor networks infrastructure, and propose a Cubic and Cross-Layer (CCL) sensor network architecture as a suitable architecture for sensor networks. CCL enables cross-layering using a notification service, adaptability of the protocols to application-specific needs, and a communication abstraction for data-centric communication. In our architecture, we argue that the sensor network has a common abstract- sensor service protocol (SSP), which can provide services rich enough for applications and keep the interface platform-independent. While many aspects of deployed sensor networks will be specific to particular applications, we have begun to identify key building blocks that will enable a wide range of applications.

The minimum-cost single-source unsplittable flow problem is a single-source multi-commodity flow problem in which each commodity should be shipped only on one single path at the minimum possible cost without violating the capacity of each edge. An outstanding open question on this problem is whether a simultaneous (2,1)-approximation can be achieved for minimizing congestion and cost. But for the general version so far the best possible ratio is (3 + 2radic(2),1). In this paper we present a polynomial-time approximation algorithms which achieves this approximation ratio, our algorithm is more efficient and easier to implement compares to previous algorithms for this problem.

This paper studies approaches to exploiting the space both within or across registers efficiently for improving the register file reliability against transient errors. The idea of our approach is based on the fact that a large number of register values are narrow (i.e., less than or equal to 16 bits for a 32-bit architecture); therefore, the upper 16 bits of the registers can be used to replicate the short operands for enhancing register integrity. This paper also adapts a prior register replication approach by selectively copying register values (i.e., long operands only) to the unused physical registers for enhancing reliability without incurring significant hardware cost. Our experiments indicate that on average, 993% register reads (regardless of short or long operands) can find their replicas available, implying significant improvement of register file integrity against transient errors.

Work on coverage and redundancy of wireless sensor networks has motivated this paper which proposes a technique based on genetic algorithms to organize different radii sensors on fields. The genetic algorithm optimizes the organization of sensors maximizing the coverage and redundant area. Based on the obtained results this paper also presents a study of the coverage and redundancy behavior having random sensor failures. By using these results it is possible to define the best number of sensors for an specific area.