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In cognitive radio applications, there are multiple different types of message queues. Existing queueing based works in underlay cognitive radio networks mainly focused on homogeneous packets. Therefore, we propose a new underlay scheme to deal with packets' heterogeneity by assuming high-priority packets have preemptive transmission opportunities over low-priority ones, and the former ones have impatient waiting time. We model the secondary user packets' behavior as a M/M/1+GI queueing system from the perspective of the whole system, which is represented by a two-dimensional state transition graph. The reneging probability of high-priority packets and the average waiting time in two-class priority queues are analyzed. Then we extend the single-channel model to multiple channels. Under this scenario, the closed form of low-priority packets' expected system delay is derived. Simulation results demonstrate that the average waiting time of high-priority packets decreases with the growing interference power threshold and the average waiting time of the low-priority packet is proportional to the arrival rate of high-priority packet and so on. This work may lay the foundation to design efficient Medium Access Control protocols and optimize long-term system performance by carefully choosing system parameters. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

We consider the problem of bit error rate (BER) degradation because of the power gain imbalance between horizontal ( H)-polarization and vertical ( V)-polarization components in an orthogonal dual-polarization transmission system. To alleviate the aforementioned BER degradation problem, we propose a non-orthogonal polarization-domain rotation scheme where the axes of H-polarization and V-polarization components are rotated with different angles at the transmitter and de-rotated at the receiver. In addition, in order to assess the effectiveness of the polarization-domain rotation scheme, we derive the closed-form BER expression under a practical dual-polarized channel model, which is represented by cross-polarization ratio and co-polarization ratio (CPR). We also derive the approximated BER expressions for the two asymptotic values of CPR: balanced CPR and infinite CPR. With the derived BER expressions, we find the optimal rotation angles that jointly minimize the BER. According to the numerical results, it is shown that about 3dB E b/ N0 gain is obtained at the BER of 10−4 and the CPR of 10dB by the polarization-domain rotation scheme with optimal rotation angles compared with the conventional orthogonal dual-polarization transmission. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Two new demodulate-and-forward schemes of multi-relay cooperative diversity with switch-and-examine relaying (SER) are analyzed. To reduce relay usage and enhance bandwidth efficiency, the two new cooperative diversity schemes employ a switch-based relay selection. The proposed schemes consume less communication resource than regular relaying schemes, such as the selection combining (SC) or maximal ratio combining (MRC) schemes that always use all relays, and also achieve better performance than distributed switch-and-stay schemes. In the first scheme, the decision statistic for relay usage and selection is based on the signal-to-noise ratio (SNR). In the second scheme, the log-likelihood ratio (LLR) of received signals is used for the decision of relay usage and selection. With the two SER schemes, the bit error probability (BEP) of binary phase shift keying (BPSK) and the average number of used paths are derived and expressed in closed-form for the independent and identically distributed (i.i.d.) Rayleigh fading channels. Numerical and simulation results are presented for performance illustrations. According to the numerical results, the LLR-based SER not only achieves a lower BEP but also consumes less relay resource than the SNR-based SER. Furthermore, the LLR-based SER scheme even outperforms the corresponding SNR-based SC scheme for a range of average SNR. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Recently, Jiang et al. and He et al. independently found security problems in Chen et al.'s remote user authentication scheme for non-tamper-proof storage devices like Universal Serial Bus stick and proposed improvements. Nonetheless, we detect that the schemes proposed by Jiang et al. and He et al. overlook a user's privacy. We also observe that Jiang et al.'s scheme is vulnerable to insider attack and denial of service attacks and lacks forward secrecy. We point out that the password changing facility in He et al.'s scheme is equivalent to undergoing registration, whereas in Jiang et al.'s scheme, it is unsuitable. Moreover, the login phase of both the schemes is incapable to prevent the use of wrong password leading to the computation of an unworkable login request. Therefore, we design a new scheme with user anonymity to surmount the identified weaknesses. Without adding much in communication/computational cost, our scheme provides more security characteristics and keeps the merits of the original schemes. As compared with its predecessor schemes, the proposed scheme stands out as a more apt user authentication method for common storage devices. We have also presented a formal proof of security of the proposed scheme based on the logic proposed by Burrows, Abadi and Needham (BAN logic). Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Two-factor user authentication scheme allows a user to use a smart card and a password to achieve mutual authentication and establish a session key between a server and a user. In 2012, Chen et al. showed that the scheme of Sood et al. does not achieve mutual authentication and is vulnerable to off-line password guessing and smart card stolen attacks. They also found that another scheme proposed by Song is vulnerable to similar off-line password guessing and smart card stolen attacks. They further proposed an improved scheme. In this paper, we first show that the improved scheme of Chen et al. still suffers from off-line password guessing and smart card stolen attacks, does not support perfect forward secrecy, and lacks the fairness of session key establishment. We then propose a new security-enhanced scheme and show its security and authentication using the formal verification tool ProVerif, which is based on applied pi calculus. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper focuses on noncoherent detection scheme for multiple-input multiple-output two-way relay channel network with two two-antennas source nodes and one single-antenna relay node. An orthogonal differential space-time network coding (ODSTNC) scheme based on relay detection and forward protocol is proposed. The proposed scheme combines space-time coding with network coding, and the differential modulation and detection are used in both multiple access stage and broadcast stage. The multiple-symbol differential detection is employed at the relay. The maximum likelihood decision and its low-complexity sphere decoding decision are given. The upper and lower bounds on the average symbol error probability for this system under differential binary phase shift keying (DBPSK) are derived, and a diversity order of 2 is confirmed to be achieved. The simulation results show that the ODSTNC scheme has good performance, and it is available for the applications of far distance signal transmission between two terminals where channel state information is unknown. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Though the introduction of the new 4th Generation mobile access technologies promises to satisfy the increasing bandwidth demand of the end-users, it poses in parallel the need for novel resource management approaches at the side of the base station. To this end, schemes that try to predict the forthcoming bandwidth demand using supervised learning methods have been proposed in the literature. However, there are still open issues concerning the training phase of such methods. In the current work, the authors propose a novel scheme that dynamically selects a proper training set for artificial neural network prediction models, based on the statistical characteristics of the collected data. It is demonstrated that an initial statistical processing of the collected data and the subsequent selection of the training set can efficiently improve the performance of the prediction model. Finally, the proposed scheme is validated using network traffic collected by real, fully operational base stations. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this study, we propose a regression forests-based cascaded method for face alignment. We build on the cascaded pose regression (CPR) framework and propose to use the regression forest as a primitive regressor. The regression forests are easier to train and naturally handle the over-fitting problem via averaging the outputs of the trees at each stage. We address the fact that the CPR approaches are sensitive to the shape initialisation; in contrast to using a number of blind initialisations and selecting the median values, we propose an intelligent shape initialisation scheme. More specifically, a large number of initialisations are propagated to a few early stages in the cascade, then only a proportion of them are propagated to the remaining cascades according to their convergence measurement. We evaluate the performance of the proposed approach on the challenging face alignment in the wild database and obtain superior or comparable performance with the state-of-the-art, in spite of the fact that we have utilised only the freely available public training images. More importantly, we show that the intelligent initialisation scheme makes the CPR framework more robust to unreliable initialisations that are typically produced by different face detections [ABSTRACT FROM AUTHOR]

The extrapolation scheme of correlation energy is revisited to evaluate the complete basis set limit from double-zeta (DZ) and triple-zeta levels of calculations. The DZ level results are adjusted to the standard asymptotic behavior with respect to the cardinal number, observed at the higher levels of basis sets. Two types of adjusting schemes with effective scaling factors, which recover errors in extrapolations with the DZ level basis set, are examined. The first scheme scales the cardinal number for the DZ level energy, while the second scheme scales the prefactor of the extrapolation function. Systematic assessments on the Gaussian-3X and Gaussian-2 test sets reveal that these calibration schemes successfully and drastically reduce errors without additional computational efforts. [ABSTRACT FROM AUTHOR]

An indoor localization technology is increasingly critical as location-aware applications evolve. Researchers have proposed several indoor localization technologies. Because most of the proposed indoor localization technologies simply involve using the received signal strength indicator value of radio-frequency identification (RFID) for indoor localization, radio-frequency interference, and environmental factors often limit the accuracy of localization results. Therefore, this study proposes an accurate RFID localization based on the neural network (ARL-N2), a passive RFID indoor localization scheme for identifying tag positions in a room, combining a location identification based on dynamic active RFID calibration algorithm with a backpropagation neural network (BPN). The proposed scheme composed of two phases: in the training phase, an appropriate BPN architecture is constructed using the training data derived from the coordinates of reference tags and the coordinates obtained using the localization algorithm. By contrast, the online phase involves calculating the tracking tag coordinates and using these values as BPN inputs, thereby enhancing the estimated location. A performance evaluation of the ARL-N2 schemes confirms its high localization accuracy. The proposed method can be used to locate critical objects in difficult-to-find areas by creating minimal errors and applying and economical technique. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Anonymous receiver encryption is an important cryptographic primitive. It allows a sender to use the public identities of multiple receivers to encrypt messages so that only the authorized receivers or a privileged set of users can decrypt the messages, and the identities of the receivers are not revealed. Recently, Zhang et al. proposed a novel anonymous multi-receiver encryption scheme and claimed that their scheme could realize the receiver's identity privacy. Unfortunately, in this paper, we pointed out that the scheme by Zhang et al. did not achieve the anonymity of the receiver identity after analyzing the security of the scheme. At the same time, we give the corresponding attack. After analyzing the reason to produce such attacks, a novel anonymous multi-receiver encryption scheme is given to achieve the anonymity of the receiver's identities. And we formally prove that the proposed scheme is semantically secure for confidentiality and receiver identities' anonymity. The security of the scheme is based on decisional bilinear Diffie-Hellman problem. Compared with the scheme by Zhang et al., Fan et al., Wang et al., and Chien et al., our scheme is shown to be better performance and robust security. To the best of our knowledge, our scheme is most efficient in terms of computational cost and communication overhead. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

As users move around in wireless local area networks, they associate with different access points in succession to maintain connectivity. Without the carefully designed association control policy, it may lead to frequent handoffs and imbalanced load, which can potentially incur unacceptable delays and poor throughput. While existing works to this issue mainly focus on minimizing the number of handoffs over time, in this paper, we propose a new association control scheme with the goal of reducing the frequency of handoffs and balancing load among access points. The defined problem, handoff optimization and load balancing (HOLB,) is mathematically described as a minimum-maximum programming. Since the HOLB problem is a nondeterministic polynomial-time hard, two constant approximation algorithms are presented to resolve it. First, we propose an α-approximation( [ABSTRACT FROM AUTHOR]

Proxy signature allows an original signer to delegate her signing capability to a proxy signer. Recently, to provide lower communication cost and stronger security, Zhang and Yu proposed a short proxy signature scheme in the standard model. They claimed that their scheme simultaneously achieves several merits including strong unforgeability, shorter signature length, and lower computational cost. However, we show that Zhang and Yu's scheme is not as secure as they claimed, because anyone can obtain the actual signing key of proxy signer from three valid proxy signatures. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Multi-proxy signature is one of the useful primitives of the proxy signature. Till now, only a few schemes of identity-based multi-proxy signature (IBMPS) have been proposed using bilinear pairings, but most of the schemes are insecure or lack a formal security proof. Because of the important application of IBMPS scheme in distributed systems, grid computing, and so on, construction of an efficient and provable-secure IBMPS scheme is desired. In 2005, Li & Chen proposed an IBMPS scheme from bilinear pairings, but their paper lacks a formal model and proof of the security. Further, in 2009, Cao & Cao presented an IBMPS scheme with the first formal security model for it. Unfortunately, their scheme is not secure against the Xiong et al's attack. In this paper, first, we present an IBMPS scheme, then we formalize a security model for the IBMPS schemes and prove that the presented scheme is existential unforgeable against adaptive chosen message and identity attack in the random oracle model under the computational Diffie-Hellman assumption. Also, our scheme is not vulnerable for the Xiong et al's attack. The presented scheme is more efficient in the sense of computation and operation time than the existing IBMPS schemes. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, we study joint resource allocation and adaptive modulation in single-carrier frequency-division multiple access systems, which is adopted as the multiple access scheme for the uplink in the 3GPP Long Term Evolution standard. We formulate an adaptive modulation and sum-cost minimization (JAMSCmin) problem. Unlike orthogonal frequency-division multiple access, in addition to the restriction of allocating a subchannel to one user at most, the multiple subchannels allocated to a user in single-carrier frequency-division multiple access systems should be consecutive as well. This renders the resource allocation problem prohibitively difficult and the standard optimization tools (e.g., Lagrange dual approach widely used for orthogonal frequency-division multiple access, etc.) cannot help towards its optimal solution. We propose a novel optimization framework for the solution of this problem that is inspired from the recently developed canonical duality theory. We first formulate the optimization problem as binary-integer programming (BIP) problem and then transform this BIP problem into continuous space canonical dual problem that is the concave maximization problem. Based on the solution of the canonical dual problem, we derive joint resource allocation and adaptive modulation algorithm, which has polynomial time complexity. We provide conditions under which the proposed algorithm is optimal. We compare the proposed algorithm with the existing algorithms in the literature. The results show a tremendous performance gain. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper proposes an ideal rateless codes model to comprehensively describe rateless codes and extends the definition of systematic linear block code to generalized systematic code. Under the proposed model, average delay, maximum disorder, and uniformity recovery entropy are introduced as performance indices to design efficient rateless codes. A novel coding scheme based on two-stage encoding and forward equal probability is proposed to optimize the proposed indices. In the first stage, the first k symbols are encoded, aiming to improve the performance of order recovery, uniformity recovery, and transmission efficiency as much as possible. In the second stage, the remaining infinite symbols are encoded, where the symbols with high degree are used to compensate the symbols loss in the first stage. Simulation results show that the proposed scheme can achieve generalized systematic rateless codes with high probability and also has less average delay and maximum disorder, better capacity achievability, and uniformity recovery performance than Luby trasform (LT) codes and rateless coded symbol sorting algorithm. Besides, the proposed scheme has the aforementioned advantages compared with expending window fountain codes except for uniformity recovery and maximum disorder performance when the erasure rate is higher than about 0.25. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY Desktop grids are platforms for grid computing that incorporate desktop resources into a grid infrastructure. The purpose of this computing paradigm is to process a massive computational tasks by exploiting the donated resources connected over the Internet. In desktop grids, it is important to guarantee fast turnaround time in the presence of dynamic properties, such as volatility and heterogeneity. To achieve this objective, we propose a task scheduling scheme based on resource clustering that can selectively allocate tasks to those resources that are most suitable for the current situation of a desktop grid environment. As a classifier of resources, the k-means clustering algorithm is introduced to classify resources according to their own task execution availability and result-return probability. The experimental results show that our scheduling scheme is more efficient than existing scheduling schemes with respect to reducing both the turnaround time and the quantity of resources consumed. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

ABSTRACT Modern medical imaging requires storage of large quantities of digitized clinical data. To provide high bandwidth and to reduce the storage space, a medical image must be compressed before transmission. One of the best image compression techniques is using the Haar wavelet transform. The method of discrete cosine transform (DCT) is chosen to be the preprocessing scheme to identify the image frequency information and has excellent energy compaction property. The block coding algorithm uses a wavelet transform to generate the sub band samples, which can be quantized and coded. It is more robust to errors than many other wavelet-based schemes. In this article, simulations are carried out on different medical Images and it demonstrates the performance in terms of peak signal to noise ratio (PSNR) & bits per pixel (BPP). Our proposed method is found to preserve information fidelity while reducing the amount of data. © 2014 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 24, 175-181, 2014 [ABSTRACT FROM AUTHOR]

ABSTRACT Three dimensional (3D) medical images possess some specific characteristics that should be utilized by an efficient compression scheme. In this article, one such compression scheme for volumetric 3D medical image data is presented. Two processes involved in this scheme are decorrelation and encoding. Decorrelation of the 3D data is realized through 3D multiwavelet transform with apt prefiltering so as to give good representation of the image which could be exploited by the encoder. Encoding is done through proposed Block Coding Algorithm, which is embedded, block based, and wavelet transform coding algorithm without maintaining any list structures. The idea behind this algorithm is to sort the 3D transform coefficients in to a 1D array with respect to declining thresholds and to use state table to keep track of the blocks and coefficients that has been coded. In the experiment conducted on various 3D magnetic resonance and computed tomography images of human brain with multiwavelets such as Geronimo-Hardin-Massopust, Chui-Lian, and orthogonal symmetric/antisymmetric (SA4), efficiency of the proposed scheme was weighed against the state of art encoders such as 3D Set Partitioning in Hierarchical Trees, 2D Set Partitioned Embedded BloCK Coder, and No List SPIHT. Attributes used for performance measurements are peak signal to noise ratio, bit rate, and structural similarity index of reconstructed image with respect to original image. © 2014 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 24, 182-192, 2014 [ABSTRACT FROM AUTHOR]

The authors present a novel approach to improve three-dimensional (3D) structure estimation from an image stream in urban scenes. The authors consider a particular setup, where the camera is installed on a moving vehicle. Applying traditional structure from motion (SfM) technique in this case generates poor estimation of the 3D structure because of several reasons such as texture-less images, small baseline variations and dominant forward camera motion. The authors idea is to introduce the monocular depth cues that exist in a single image, and add time constraints on the estimated 3D structure. The scene is modelled as a set of small planar patches obtained using over-segmentation, and the goal is to estimate the 3D positioning of these planes. The authors propose a fusion scheme that employs Markov random field model to integrate spatial and temporal depth features. Spatial depth is obtained by learning a set of global and local image features. Temporal depth is obtained via sparse optical flow based SfM approach. That allows decreasing the estimation ambiguity by forcing some constraints on camera motion. Finally, the authors apply a fusion scheme to create unique 3D structure estimation. [ABSTRACT FROM AUTHOR]

SUMMARY Long term evolution constitutes the next generation cellular network beyond 3G that is designed to support the explosion in demand for bandwidth-hungry multimedia services in wireless networks by providing an extremely high performance radio access technology. To support multimedia broadcast/multicast services (MBMS), long term evolution offers the functionality to transmit MBMS over a single frequency network, where a time-synchronized common waveform is transmitted from multiple cells for a given duration. This enables over-the-air combining, thus significantly improving the spectral efficiency (SE) compared with conventional MBMS operations. In MBMS over a single frequency network transmissions, the achieved SE is mainly determined by the modulation and coding scheme selected. This study proposes and evaluates four approaches for the selection of the modulation and coding scheme. Each approach corresponds to different users' distribution and multimedia traffic conditions. On the basis of SE measurements, we determine the approach that either maximizes or achieves a target SE for the corresponding users' distribution and traffic conditions. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

By examining the diversity-multiplexing tradeoff (DMT) of an amplify-and-forward (AF) multi-antenna multi-relay network, a procedure to select the optimal number of relays and relay candidates is established. Subsequently, a distributed BLAST transmission scheme in conjunction with successive nulling and cancellation at destination is proposed to achieve the optimal DMT. Illustrative results indicate that the proposed method can significantly enhance the outage probability performance, and for a selected number of relays in use, the performance enhancement can be further improved by increasing the number of available relays in the AF network. Copyright © 2010 John Wiley & Sons, Ltd. A distributed BLAST transmission scheme in conjunction with successive nulling and cancellation at destination is proposed to achieve the optimal DMT. Illustrative results indicate that the proposed method can significantly enhance the outage probability performance, and for a selected number of relays in use, the performance enhancement can be further improved by increasing the number of available relays in the amplify-and-forward (AF) network. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In three-party password-based key exchange protocol, a client is allowed to share a human-memorable password with a trusted server such that two clients can negotiate a session key to communicate with each other secretly. Recently, many three-party password-based key exchange protocols have been developed. However, these proposed schemes cannot simultaneously achieve security and efficiency. Based on elliptic curve cryptography (ECC), this paper will propose a new simple three-party password-based authenticated key exchange scheme. The proposed method not only reduces computation cost for remote users and a trusted server but also is more efficient than previously proposed schemes. It is better suited for resource constrained devices, such as smart cards or mobile units. Copyright © 2010 John Wiley & Sons, Ltd. Recently, many three-party password-based key exchange protocols have been developed. However, these proposed schemes cannot simultaneously achieve security and efficiency. Based on elliptic curve cryptography (ECC), this paper, will propose a new simple three-party password-based authenticated key exchange protocol. The proposed method not only reduces computation cost for remote users and a trusted server but also is more efficient than previously proposed schemes. It is better suited for resource constrained devices, such as smart cards or mobile units. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

While conventional frequency reuse techniques need to allocate mutually exclusive frequency resources to adjacent cells, this paper proposes a technique for OFDMA systems to use pseudo-random subchannel allocation patterns based on the preamble number. Although sophisticated cell planning is not required for the proposed technique, irregular frequency patterns can allow efficient interference avoidance and high data throughput. Copyright © 2010 John Wiley & Sons, Ltd. While conventional frequency reuse techniques need to allocate mutually exclusive frequency resources to adjacent cells, this paper proposes a technique for OFDMA systems to use pseudo-random subchannel allocation patterns based on the preamble number. Although sophisticated cell planning is not required for the proposed technique, irregular frequency patterns can allow efficient interference avoidance and high data throughput. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The paper proposes Spatiotemporal Clustering and Compressing Schemes for data collection applications on wireless sensor networks. The proposed one-round distributed clustering scheme and lightweight compressing algorithm are high cost effective and low energy consumption compared with previous work. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In 1998, a revolutionary system of angiosperm classification, the Angiosperm Phylogeny Group system was published. Meanwhile, another new system of classification of angiosperms, the eight-class system was proposed by C. Y. Wu and colleagues based on long term work on the flora of China. The Flora Reipublicae Popularis Sinicae project was initiated in 1959 and completed by 2004. It is the largest Flora so far completed in the world, including 31 228 species of vascular plants, or one-eighth of the global plant diversity. The English-language and updated Flora of China (FOC) is an international joint effort initiated in 1988 and accelerated in 1998. Up to now, 15 of the 24 volumes of the FOC have been published. Based on the floristic data, the composition, characteristics, floristic divisions and affinities of the flora of China have been studied by Wu and colleagues since 1965. In the past 10 years, analyses of the available floristic data have been very productive. The East Asiatic Floristic Kingdom was proposed in 1998. All 346 families of angiosperms in China, according to the eight-class system of classification, were comprehensively discussed by using knowledge of current and historical distribution of seed plants in the world, together with some morphological and molecular data. A scheme of distribution patterns or areal-types of families and genera of seed plants in China was modified and elucidated, together with a proposed scheme of areal-types of the world. Molecular phylogenetic and biogeographical studies of angiosperms in China in the past 10 years also witnessed a progressive development. Integration of morphological and molecular data and fossil evidence revealed some significant results. Eastern Asia, which used to be regarded as an important center of survival during the ice age, is likely an important center of diversification of angiosperms. [ABSTRACT FROM AUTHOR]

In order to establish encrypted communications in deployable sensor networks, it is essential that encryption keys be shared between nodes. However, the sharing of keys is not simple given the restricted resources of such devices. In recent years, several random key predistribution schemes have been proposed; in the scheme proposed by Du and colleagues, improved performance is achieved by using information regarding the deployment location when predistributing keys. However, this scheme suffers from the problem that it is possible to apply only for the so-called group deployment model whereby nodes are partitioned into groups and deployed from locations that are arranged systematically. In this paper we propose a random key predistribution scheme that can be applied to arbitrary deployment models by making use of probability distribution information regarding the deployment when the key predistribution is performed. In addition, we confirm from computational experiments that this method is able to construct networks that are more consolidated than those created by Du and colleagues' scheme. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 90(10): 73–83, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.20390 [ABSTRACT FROM AUTHOR]

This study investigated how a schematic-based visualisation approach implemented in an electronic learning environment facilitated the learning of the complex programming concept. The semantic-based visualisation approach applied Visualcode Rules and utilised various pictorial notations modeling the execution of recursive procedures. In this study, 38 college students studied the Scheme language and its recursive procedures in three different conditions. The three conditions were (a) the VisualScheme environment in which schematic-based pictorial notations (e.g. coloured icons and environment trees) were employed to help learners trace intermediate steps of executing procedures; (b) an Internet learning environment in which an ordered sequence of static pictorial notations provide a snap shot and illuminate execution of recursive procedures; (c) an Internet learning environment in which on-line source codes were annotated with detailed textual information. Results of the study indicated schematic-based pictorial notations helped students to form a better conceptual framework for learning the concept of recursion. It is suggested that the design of an electronic learning environment may appropriately apply meaningful pictorial information to help students learn complex programming concepts. [ABSTRACT FROM AUTHOR]

This paper describes the behavior of the processing element (PE) generally used in applying the data-flow control scheme to signal processing equipment in the switching system or in the computer system. A performance evaluation is presented in terms of the characteristics based on the theoretical analysis. It is important in this scheme to evaluate the time until the program execution is completed (program execution time) for the given parallelism of the data-flow program and the multiplicity of the program (task). As a preliminary to the estimation of the program execution time, this paper evaluates PE as a whole. First, the matching-store unit of FE is considered. A simple numerical analysis based on the traffic model is presented and the performance is evaluated. The characteristics such as the mean number of waiting calls and the mean waiting time are calculated. Using those results, the whole PE is modeled as a BCMP-type queueing network, and the mean cycle time is derived. Finally, the result of numerical calculation and the result of simulation are illustrated. The range of application is described, together with some discussions. [ABSTRACT FROM AUTHOR]

Multilevel coding (MLC) provides a low-complexity encoding scheme for lattices obtained via construction D. On the other hand, multistage decoding is also a practical decoding scheme for MLC provided that the underlying error correcting codes are capacity achieving, which requires using a powerful soft decoder for each code. Proposed is an approximation of the log-likelihood ratio (LLR) which used for the soft decoding of the different error correcting codes employed in the lattice construction. This approximation is based on the von Mises distribution and achieves, with lower complexity, the same error rate performance obtained with the exact LLR calculation. [ABSTRACT FROM AUTHOR]