Recently, design of sparse finite impulse response (FIR) digital filters has attracted much attention due to its ability to reduce the implementation cost. However, finding a filter with the fewest number of nonzero coefficients subject to prescribed frequency domain constraints is a rather difficult problem because of its non-convexity. In this paper, an algorithm based on binary particle swarm optimization (BPSO) is proposed, which successively thins the filter coefficients until no sparser solution can be obtained. The proposed algorithm is evaluated on a set of examples, and better results can be achieved than other existing algorithms.

The reliability of electromagnetic relay (EMR) which contains a permanent magnet (PM) can be improved by a robust design method. In this parameter design process, the calculation of electromagnetic system is very important. In analytical calculation, PM is often equivalent to a lumped parameter model of one magnetic resistance and one magnetic potential, but significant error is often caused; in order to increase the accuracy, a distributed parameter calculation model (DPM) of PM bar is established; solution procedure as well as verification condition of this model is given; by a case study of the single PM bar, magnetic field lines division method is adopted to build the DPM, the starting point and section magnetic flux of each segment are solved, a comparison is made with finite element method (FEM) and measured data; the accuracy of this magnetic field line based distributed parameter model (MFDPM) in PM bar is verified; this model is applied to the electromagnetic system of a certain type EMR, electromagnetic system calculation model is established based on MFDPM, and the static force is calculated under different rotation angles; compared with traditional lumped parameter model and FEM, it proves to be of acceptable calculation accuracy and high calculation speed which fit the requirement of robust design.

Although multi-user multiple-input multiple-output (MI-MO) systems provide high data rate transmission, they may suffer from interference. Block diagonalization and eigenbeam-space division multiplexing (E-SDM) can suppress interference. The transmitter needs to determine beamforming weights from channel state information (CSI) to use these techniques. However, MIMO channels change in time-varying environments during the time intervals between when transmission parameters are determined and actual MIMO transmission occurs. The outdated CSI causes interference and seriously degrades the quality of transmission. Channel prediction schemes have been developed to mitigate the effects of outdated CSI. We evaluated the accuracy of prediction of autoregressive (AR)-model-based prediction and Lagrange extrapolation in the presence of channel estimation error. We found that Lagrange extrapolation was easy to implement and that it provided performance comparable to that obtained with the AR-model-based technique.

This image sharing method is a secure way of protecting the security of the secret images. In 2011, Wang et al. proposed an image sharing method with verification. The idea of the method is to embed the secret and the watermark images into two shares by two equations to achieve the goal of the secret sharing. However, the constructed shares are meaningless images which are difficult to manage. Authors utilize the algorithm of the torus automorphism to increase the security of the shares. However, the algorithm of the torus automorphism must take much time to encrypt and decrypt an image. This paper proposes a friendly image sharing method to improve the above problem. Experimental results show the significant efficiency of the proposed method.

In this paper, the low density generator matrix (LDGM) coded scheme with unequal transmission power allocation (UTPA) in optical wireless channel is evaluated by computer simulation. In particular, the bit error rate performance of the LDGM-coded binary pulse position modulation (LDGM-BPPM) with the UTPA scheme is investigated in the presence of avalanche photo diode (APD) noise, scintillation and background noise. Consequently, the BER performance of the LDGM-BPPM with UTPA is better than that of the conventional LDGM-BPPM. It is found that there is the optimum power ratio (R). The optimum R varies with scintillation and background noise. For example, when the average received laser power is -47[dBm], the variance of scintillation is 0.1, and background noise is -45[dBm], the optimum R is 3.1. Thus, the LDGM-BPPM with the UTPA scheme is superior to the conventional LDGM-BPPM system.

It is shown that an infinite lumped-element LC- ladder network generates all Bessel functions Jn(t) of the first kind as a response to a single non-zero initial condition. Closed-form expressions for the voltage responses in the time domain are presented if the LC- ladder is driven by a step-like input voltage.

In consideration of the image noise captured by photoelectric cameras at nighttime, a robust motion detection algorithm based on sparse representation is proposed in this study. A universal dictionary for arbitrary scenes is presented. Realistic and synthetic experiments demonstrate the robustness of the proposed approach.

Chronic liver disease is a major worldwide health problem. Diagnosis and staging of chronic liver diseases is an important issue. In this paper, we propose a quantitative method of analyzing local morphological changes for accurate and practical computer-aided diagnosis of cirrhosis. Our method is based on sparse and low-rank matrix decomposition, since the matrix of the liver shapes can be decomposed into two parts: a low-rank matrix, which can be considered similar to that of a normal liver, and a sparse error term that represents the local deformation. Compared with the previous global morphological analysis strategy based on the statistical shape model (SSM), our proposed method improves the accuracy of both normal and abnormal classifications. We also propose using the norm of the sparse error term as a simple measure for classification as normal or abnormal. The experimental results of the proposed method are better than those of the state-of-the-art SSM-based methods.

In anonymous reputation systems, where after an interaction between anonymous users, one of the users evaluates the peer by giving a rating. Ratings for a user are accumulated, which becomes the reputation of the user. By using the reputation, we can know the reliability of an anonymous user. Previously, anonymous reputation systems have been proposed, using an anonymous e-cash scheme. However, in the e-cash-based systems, the bank grasps the accumulated reputations for all users, and the fluctuation of reputations. These are private information for users. Furthermore, the timing attack using the deposit times is possible, which makes the anonymity weak. In this paper, we propose an anonymous reputation system, where the reputations of users are secret for even the reputation manager such as the bank. Our approach is to adopt an anonymous credential certifying the accumulated reputation of a user. Initially a user registers with the reputation manager, and is issued an initial certificate. After each interaction with a rater, the user as the ratee obtains an updated certificate certifying the previous reputation summed up by the current rating. The update protocol is based on the zero-knowledge proofs, and thus the reputations are secret for the reputation manager. On the other hand, due to the certificate, the user cannot maliciously alter his reputation.

This study proposes a novel method for evaluating the transmission characteristics of a three-phase filter using the “Fortescue-mode S-parameters,” which are S-parameters whose variables are transformed into symmetrical coordinates (i.e., zero-/positive-/negative-phase sequences). The behavior of the filter under three-phase current, including its non-symmetry, can be represented by these S-parameters, without regard to frequency. This paper also describes a methodology for creating modal equivalent circuits that reflect Fortescue-mode S-parameters allowing the effects of circuit components on filter characteristics to be estimated. Thus, this method is useful not only for the measurement and evaluation but also for the analysis and design of a three-phase filter. In addition, the physical interpretation of asymmetrical/symmetrical insertion losses and the conversion method based on Fortescue-mode S-parameters are clarified.

Single-thread performance has not improved much over the past few years, despite an ever increasing transistor budget. One of the reasons for this is that there is a speed gap between the processor and main memory, known as the memory wall. A promising method to overcome this memory wall is aggressive out-of-order execution by extensively enlarging the instruction window resources to exploit memory-level parallelism (MLP). However, simply enlarging the window resources lengthens the clock cycle time. Although pipelining the resources solves this problem, it in turn prevents instruction-level parallelism (ILP) from being exploited because issuing instructions requires multiple clock cycles. This paper proposed a dynamic scheme that adaptively resizes the instruction window based on the predicted available parallelism, either ILP or MLP. Specifically, if the scheme predicts that MLP is available during execution, the instruction window is enlarged and the window resources are pipelined, thereby exploiting MLP. Conversely, if the scheme predicts that less MLP is available, that is, ILP is exploitable for improved performance, the instruction window is shrunk and the window resources are de-pipelined, thereby exploiting ILP. Our evaluation results using the SPEC2006 benchmark programs show that the proposed scheme achieves nearly the best performance possible with fixed-size resources. On average, our scheme realizes a performance improvement of 21% over that of a conventional processor, with additional cost of only 6% of the area of the conventional processor core or 3% of that of the entire processor chip. The evaluation results also show 8% better energy efficiency in terms of 1/EDP (energy-delay product).

This paper proposes an efficient two-scan labeling algorithm for binary hexagonal images. Unlike conventional labeling algorithms, which process pixels one by one in the first scan, our algorithm processes pixels two by two. We show that using our algorithm, we can check a smaller number of pixels. Experimental results demonstrated that our method is more efficient than the algorithm extended straightly from the corresponding labeling algorithm for rectangle binary images.

We propose a synthesis method of nested loops into parallelized circuits by integrating the polyhedral optimization, which is a state-of-the-art technique in the field of software, into high-level synthesis. Our method constructs circuits equipped with multiple processing elements (PEs), using information generated by the polyhedral optimizing compiler. Since multiple PEs cannot concurrently access the off-chip RAM, a method for constructing on-chip buffers is also proposed. Our buffering method reduces the off-chip RAM access conflicts and further enables burst accesses and data reuses. In our experimental result, the buffered circuits generated by our method are 8.2 times on average and 26.5 times at maximum faster than the sequential non-buffered ones, when each of the parallelized circuits is configured with eight PEs.

Maximally flat digital differentiators (MFDDs) are widely used in many applications. By using MFDDs, we obtain the derivative of an input signal with high accuracy around their center frequency of flat property. Moreover, to avoid the influence of noise, it is desirable to attenuate the magnitude property of MFDDs expect for the vicinity of the center frequency. In this paper, we introduce a design method of linear phase FIR band-pass MFDDs with an arbitrary center frequency. The proposed transfer function for both of TYPE III and TYPE IV can be achieved as a closed form function using Jacobi polynomial. Furthermore, we can easily derive the weighting coefficients of the proposed MFDDs using recursive formula. Through some design examples, we confirm that the proposed method can adjust the center frequency arbitrarily and the band width having flat property.

We propose a cyclic sleep control technique for backup resources in reconfigurable optical add/drop multiplexer (ROADM) systems to simultaneously achieve power savings and high-speed recovery from failures. Processes to check the reliability of backup resources, backup transponders and paths, are also provided in the control technique. The proposed technique uses sleep mode where backup transponders are powered down to minimize power for power savings. At least one of the backup transponders is always activated after self-checking using the loopback fiber connection in the ROADM and it becomes a shared backup for working transponders to enable high-speed recovery from failures. This activated backup transponder is powered down again after the next transponder is activated. These state transitions are cyclically applied to each backup transponder. This “cyclic” aspect of operation enables network operators to continuously monitor the reliability for all backup resources with the sleep mode. The activated backup transponders at both ends of the path are used in checking the reliability of backup paths. Therefore, all backup resources, both transponders and paths, can be regularly checked with the sleep mode to ensure data are stably forwarded. We estimated the power consumption with this technique under various conditions and found a trade-off between power reduction and the recovery capabilities from failures. We achieved more than 34% power saving of backup transponders maintaining the failure recovery time within 50ms in experiments. Furthermore, we confirmed the reliability of backup paths in experiments using backup transponders with the cyclic sleep control technique. These results indicated that the proposed control technique is promising in dramatically and reliably reducing the power consumption of backup resources.

Subcarrier pairing (SP) and power allocation (PA) can improve the channel capacity of the OFDM multi-hop relay system. Due to limitations of processing complexity and energy consumption, symbol-level relaying, which only regenerates the constellation symbols at relay nodes, is more practical than code-level relaying that requires full decoding and encoding. By modeling multi-hop symbol-level relaying as a multi-staged parallel binary symmetric channel, this paper introduces a jointly optimal SP and PA scheme which maximizes the end to end data rate. Analytical arguments are given to reveal the structures and properties of the optimal solution, and simulation results are presented to illustrate and justify the optimality.

This paper proposes an adaptive band activity ratio control (ABC) with cascaded energy allocation (CEA) scheme to improve end-to-end spectral efficiency for two-hop amplify-and-forward orthogonal frequency division multiplexing relay systems under transmit energy constraint. Subchannel pairing (SP) based spectrum mapping maps spectral components transmitted over high gain subchannels in the source-to-relay link onto high gain subchannels of the relay-to-destination link to improve the spectral efficiency. However, SP suffers from a frame efficiency reduction due to the notification of information of spectral component order. To compensate for the deficiency of SP, the proposed scheme employs dynamic spectrum control with ABC in which spectral components are mapped onto subchannels having high channel gain in each link, while band activity ratio (BAR) is controlled to an optimal value, which is smaller than 1, so that all spectral components are transmitted over relatively high gain subchannels of the two links. To further improve the performance, energy allocation at the source node and the relay node is serially conducted based on convex optimization, and BAR is controlled to improve discrete-input continuous-output memoryless channel capacity at the relay node. In the proposed scheme, since only information of BAR needs to be notified, the notification overhead is drastically reduced compared to that in SP based spectrum mapping. Numerical analysis confirms that the proposed ABC combined with CEA significantly reduces the required notification overhead while achieving almost the same frame error rate performance compared with the SP based scheme.

This paper presents a prediction model based on historical data to achieve optimal values of pipelining, concurrency and parallelism (PCP) in GridFTP data transfers in Cloud systems. Setting the correct values for these three parameters is crucial in achieving high throughput in end-to-end data movement. However, predicting and setting the optimal values for these parameters is a challenging task, especially in shared and non-predictive network conditions. Several factors can affect the optimal values for these parameters such as the background network traffic, available bandwidth, Round-Trip Time (RTT), TCP buffer size, and file size. Existing models either fail to provide accurate predictions or come with very high prediction overheads. The author shows that new model based on historical data can achieve high accuracy with low overhead.

In this paper, we present update rules for convolutive nonnegative matrix factorization (NMF) in which cost functions are based on the squared Euclidean distance, the Kullback-Leibler (KL) divergence and the Itakura-Saito (IS) divergence. We define an auxiliary function for each cost function and derive the update rule. We also apply this method to the single-channel signal separation in speech signals. Experimental results showed that the convergence of our KL divergence-based method was better than that in the conventional method, and our method achieved single-channel signal separation successfully.

The outage capacity of the fading cognitive multicast channel (CMC) is investigated in this paper. Assume that the instantaneous channel state information (CSI) of the interference link between the cognitive base station (CBS) and the primary user (PU) is available at the CBS, we derive the outage capacity in Rayleigh fading environments under the interference power and the transmit power constraints. Under the condition that the interference power limit is sufficiently larger or smaller than the transmit power limit, the asymptotic outage capacity is obtained in closed-form. Assume that only the channel distribution information (CDI) of the interference link is available at the CBS, the outage capacity under the interference outage and the transmit power constraints is derived in closed-form. The theoretical results are confirmed by simulations. It is shown that the outage capacity is not degraded due to partial knowledge of the interference link when the interference power limit is sufficiently larger than the transmit power limit. It is also shown that the capacity gain due to increasing the number of the secondary users (SUs) is negligible if the number of the SUs is already large. Additionally, the case of CDI with estimation error is also investigated. Interestingly, we show that the estimation error of CDI may be a positive factor for improving the outage capacity of the CMC.