The main idea of filter methods in feature selection is constructing a feature-assessing criterion and searching for feature subset that optimizes the criterion. The primary principle of designing such criterion is to capture the relevance between feature subset and the class as precisely as possible. It would be difficult to compute the relevance directly due to the computation complexity when the size of feature subset grows. As a result, researchers adopt approximate strategies to measure relevance. Though these strategies worked well in some applications, they suffer from three problems: parameter determination problem, the neglect of feature interaction information and overestimation of some features. We propose a new feature selection algorithm that could compute mutual information between feature subset and the class directly without deteriorating computation complexity based on the computation of partitions. In light of the specific properties of mutual information and partitions, we propose a pruning rule and a stopping criterion to accelerate the searching speed. To evaluate the effectiveness of the proposed algorithm, we compare our algorithm to the other five algorithms in terms of the number of selected features and the classification accuracies on three classifiers. The results on the six synthetic datasets show that our algorithm performs well in capturing interaction information. The results on the thirteen real world datasets show that our algorithm selects less yet better feature subset.

A new Waffle-iron Ridge Guide (WRG) structure that has the ability to control both wavelength and impedance is proposed. With the proposed structure, not only can the wavelength be controlled over a wide range for both fast- and slow-waves in free space but the impedance can also be controlled. These features can improve the performance of array antennas in terms of reducing grating lobes and side lobes. In this paper, we discuss and evaluate a design scheme using equivalent circuits and EM-simulation. This paper also discusses how the conductivity and dielectric loss in the WRG affect the total gain of the array antenna.

Many text entry methods are available in the use of touch interface devices when using a screen reader, and blind smartphone users and their supporters are eager to know which one is the easiest to learn and the fastest. Thus, we compared the text entry speeds and error counts for four combinations of software keyboards and character-selecting gestures over a period of five days. The split-tap gesture on the Japanese numeric keypad was found to be the fastest across the five days even though this text entry method produced the most errors. The two entry methods on the QWERTY keyboard were slower than the two entry methods on the numeric keypad. This difference in text entry speed was explained by the differences in key pointing and tapping times and their repitition numbers among different methods.

In this paper, we consider a similarity control problem for nondeterministic discrete event systems, which requires us to synthesize a nonblocking supervisor such that the supervised plant is simulated by a given specification. We assume that a supervisor can observe not only the event occurrence but also the current state of the plant. We present a necessary and sufficient condition for the existence of a nonblocking supervisor that solves the similarity control problem and show how to verify it in polynomial time. Moreover, when the existence condition of a nonblocking supervisor is satisfied, we synthesize such a supervisor as a solution to the similarity control problem.

This research addresses improvements in the efficiency of spectrum utilization by defending against jamming attacks and corrupting the communications of the adversary network by executing its own jamming strategy. The proposed scheme, based on game theory, selects the best operational strategy (i.e., communications and jamming strategies) to maximize the successful communications and jamming rates of the network. Moreover, an estimation algorithm is investigated to predict the behavior of the adversary network in order to improve the efficiency of the proposed game theory-based scheme.

A compact uniplanar antenna design for tablet/laptop applications is proposed. The main design principle of this antenna is the use of the coupling-feed mechanism. The proposed antenna is composed of an inverted L-shaped parasitic element, T-shaped feeding strip, parasitic shorted strip, and a step tuning stub. With its small size of 55mm × 15mm × 0.8mm, the proposed antenna is able to excite dual wideband transmission over the full LTE/WWAN operation ranges of 698-960MHz and 1710-2690MHz. Furthermore, the proposed antenna also exhibits reduced ground effects, such that reducing the ground size of the proposed antenna will not affect its performance.

Precise determination of antenna phase centers is crucial to reduce the uncertainty in gain when employing the three-antenna method, particularly when the range distances are short-such as a 3-m radio anechoic chamber, where the distance between the phase centers and the open ends of an aperture antenna (the most commonly-used reference) is not negligible compared with the propagation distance. An automatic system to determine the phase centers of aperture antennas in a radio anechoic chamber is developed. In addition, the absolute gain of horn antennas is evaluated using the three-antenna method. The phase centers of X-band pyramidal horns were found to migrate up to 18mm from the open end. Uncertainties in the gain were evaluated in accordance with ISO/IEC Guide 93-3: 2008. The 95% confidence interval of the horn antenna gain was reduced from 0.57 to 0.25dB, when using the phase center location instead of the open end. The phase centers, gains, polarization, and radiation patterns of space-borne antennas are measured: low and medium-gain X-band antennas for an ultra small deep space probe employing the polarization pattern method with use of the horn antenna. The 95% confidence interval in the antenna gain decreased from 0.74 to 0.47dB.

Three-dimensional (3-D) scattering center models use a finite number of point scatterers to efficiently represent complex radar target signature. Using the CLEAN algorithm, 3-D scattering center model is extracted from the inverse synthetic aperture radar (ISAR) image, which is generated based on the shooting and bouncing ray (SBR) technique. The conventional CLEAN extracts the strongest peak iteratively based on the assumption that the scattering centers are isolated. In a realistic target, however, both interference from the closely spaced points and additive noise distort the extraction process. This paper proposes a matched filter-based CLEAN algorithm to improve accuracy efficiently. Using the matched filtering of which impulse response is the known point spread function (PSF), a point most correlated with the PSF is extracted. Thus, the proposed method optimally enhances the accuracy in the presence of massive distortions. Numerical simulations using canonical and realistic targets demonstrate that the extraction accuracy is improved without loss of time-efficiency compared with the existing CLEAN algorithms.

This paper proposes a novel method of reducing channel state information (CSI) feedback by using transmit antenna selection for downlink multiuser multiple input multiple output (DL-MU-MIMO) transmission in dense distributed antenna systems. It is widely known that DL-MU-MIMO transmission achieves higher total bit-rate by mitigating inter-user interference based on pre-coding techniques. The pre-coding techniques require CSI between access point (AP) and multiple users. However, overhead for CSI acquisition degrades the transmission efficiency of DL-MU-MIMO transmission. In the proposed CSI feedback reduction method, AP first selects the antenna set that maximizes the received power at each user, second it skips the sequence of CSI feedback for users whose signal to interference power ratio is larger than a threshold, and finally it performs DL-MU-MIMO transmission to multiple users by using the selected antenna set. To clarify the proposed method, we evaluate it by computer simulations in an indoor scenario. The results show that the proposed method can offer higher transmission efficiency than the conventional DL-MU-MIMO transmission with the usual CSI feedback method.

In-band full-duplex (FD) Multiple-Input and Multiple-Output (MIMO) communication performs uplink and downlink transmission at the same time using the same frequency. In this system, the spectral efficiency is theoretically double that of conventional duplex schemes, such as Time Division Duplex (TDD) and Frequency Division Duplex (FDD). However, this system suffers interference because the uplink and downlink streams coexist within the same channel. Especially at the terminal side, it is quite difficult for the terminal to eliminate the interference signals from other terminals since it has no knowledge about the contents of the interference signals. This paper presents an inter-terminal interference suppression method between the uplink and downlink signals assuming the multi-user environment. This method uses eigen-beamforming at the transmitting terminal to direct the null to the other terminal. Since this beamforming technique reduces the degrees of freedom available, the interference suppression performance and transmitting data-rate have a trade-off relation. This study investigates the system capacity characteristics in multi-user full-duplex MIMO communication using the propagation channel information measured in an actual outdoor experiment and shows that the proposed communication scheme offers higher system capacity than the conventional scheme.

The Transmission Control Protocol (TCP) with Network Coding (TCP/NC) was proposed to introduce packet loss recovery ability at the sink without TCP retransmission, which is realized by proactively sending redundant combination packets encoded at the source. Although TCP/NC is expected to mitigate the goodput degradation of TCP over lossy networks, the original TCP/NC does not work well in burst loss and time-varying channels. No apparent scheme was provided to decide and change the network coding-related parameters (NC parameters) to suit the diverse and changeable loss conditions. In this paper, a solution to support TCP/NC in adapting to mentioned conditions is proposed, called TCP/NC with Loss Rate and Loss Burstiness Estimation (TCP/NCwLRLBE). Both the packet loss rate and burstiness are estimated by observing transmitted packets to adapt to burst loss channels. Appropriate NC parameters are calculated from the estimated probability of successful recoverable transmission based on a mathematical model of packet losses. Moreover, a new mechanism for coding window handling is developed to update NC parameters in the coding system promptly. The proposed scheme is implemented and validated in Network Simulator 3 with two different types of burst loss model. The results suggest the potential of TCP/NCwLRLBE to mitigate the TCP goodput degradation in both the random loss and burst loss channels with the time-varying conditions.

Wireless Sensor Networks (WSNs) are randomly deployed in a hostile environment and left unattended. These networks are composed of small auto mouse sensor devices which can monitor target information and send it to the Base Station (BS) for action. The sensor nodes can easily be compromised by an adversary and the compromised nodes can be used to inject false vote or false report attacks. To counter these two kinds of attacks, the Probabilistic Voting-based Filtering Scheme (PVFS) was proposed by Li and Wu, which consists of three phases; 1) Key Initialization and assignment, 2) Report generation, and 3) En-route filtering. This scheme can be a successful countermeasure against these attacks, however, when one or more nodes are compromised, the re-distribution of keys is not handled. Therefore, after a sensor node or Cluster Head (CH) is compromised, the detection power and effectiveness of PVFS is reduced. This also results in adverse effects on the sensor network's lifetime. In this paper, we propose a Fuzzy Rule-based Key Redistribution Method (FRKM) to address the limitations of the PVFS. The experimental results confirm the effectiveness of the proposed method by improving the detection power by up to 13.75% when the key-redistribution period is not fixed. Moreover, the proposed method achieves an energy improvement of up to 9.2% over PVFS.

Hadoop is a popular open-source MapReduce implementation. In the cases of jobs, wherein huge scale of output files of all relevant Map tasks are transmitted into Reduce tasks, such as TeraSort, the Reduce tasks are the bottleneck tasks and are I/O bounded for processing many large output files. In most cases, including TeraSort, the intermediate data, which include the output files of the Map tasks, are large and accessed sequentially. For improving the performance of these jobs, it is important to increase the sequential access performance. In this paper, we propose methods for improving the performance of Reduce tasks of such jobs by considering the following two things. One is that these files are accessed sequentially on an HDD, and the other is that each zone in an HDD has different sequential I/O performance. The proposed methods control the location to store intermediate data by modifying block bitmap of filesystem, which manages utilization (free or used) of blocks in an HDD. In addition, we propose striping layout for applying these methods for virtualized environment using image files. We then present performance evaluation of the proposed method and demonstrate that our methods improve the Hadoop application performance.

Seed detection or sometimes known as nuclei detection is a prerequisite step of nuclei segmentation which plays a critical role in quantitative cell analysis. The detection result is considered as accurate if each detected seed lies only in one nucleus and is close to the nucleus center. In previous works, voting methods are employed to detect nucleus center by extracting the nucleus saliency features. However, these methods still encounter the risk of false seeding, especially for the heterogeneous intensity images. To overcome the drawbacks of previous works, a novel detection method is proposed, which is called secant normal voting. Secant normal voting achieves good performance with the proposed skipping range. Skipping range avoids over-segmentation by preventing false seeding on the occlusion regions. Nucleus centers are obtained by mean-shift clustering from clouds of voting points. In the experiments, we show that our proposed method outperforms the comparison methods by achieving high detection accuracy without sacrificing the computational efficiency.

Graph sampling is an effective method to sample a representative subgraph from a large-scale network. Recently, researches have proven that several classical sampling methods are able to produce graph samples but do not well match the distribution of the graph properties in the original graph. On the other hand, the validation of these sampling methods and the scale of a good graph sample have not been examined on weighted graphs. In this paper, we propose the weighted graph sampling problem. We consider the proper size of a good graph sample, propose novel methods to verify the effectiveness of sampling and test several algorithms on real datasets. Most notably, we get new practical results, shedding a new insight on weighted graph sampling. We find weighted random walk performs best compared with other algorithms and a graph sample of 20% is enough for weighted graph sampling.

This paper proposes a scheme for automatic generation of mixed-integer programming problems for scheduling with multiple resources based on colored timed Petri nets. Our method reads Petri net data modeled by users, extracts the precedence and conflict relations among transitions, information on the available resources, and finally generates a mixed integer linear programming for exactly solving the target scheduling problem. The mathematical programing problems generated by our tool can be easily inputted to well-known optimizers. The results of this research can extend the usability of optimizers since our tool requires just simple rules of Petri nets but not deep mathematical knowledge.

Japan Broadcasting Corporation (NHK) started test satellite broadcasting of ultra-high-definition television (UHDTV) on August 1st, 2016. The test broadcasting is being provided in the 12-GHz (11.7 to 12.75GHz) band with right-hand circular polarization. In 2018, left-hand circular polarization in the same frequency band will be used for satellite broadcasting of UHDTV. Because UHDTV satellite broadcasting uses the 16APSK modulation scheme, which requires a higher carrier-to-noise ratio than that used for HDTV in Japan, it is important to mitigate the cross-polarization interference. Therefore, we fabricated and tested a dual-circularly polarized offset parabolic reflector antenna that has a feed antenna composed of a 2×2 microstrip antenna array, which is sequentially rotated to enhance the polarization purity. Measured results showed that the fabricated antenna complied with our requirements, a voltage standing wave ratio of less than 1.4, antenna gain of 34.5dBi (i.e., the aperture efficiency was 69%), and cross-polarization discrimination of 28.7dB.

To effectively analyze the influence of two-wave with diffuse power (TWDP) fading on the achievable error rate performance of binary phase-shift keying (BPSK) signaling, we derive two novel concise asymptotic closed-form bit error rate (BER) formulas. We perform asymptotic analysese based on existing exact and approximate BER formulas, which are obtained from the exact probability density function (PDF) or moment generating function (MGF), and the approximate PDF of TWDP fading. The derived asymptotic closed-form expressions yield explicit insights into the achievable error rate performance in TWDP fading environments. Furthermore, the absolute relative error (ARE) between the exact and approximate coding gains is investigated, from which we also propose a criterion for the order of an approximate PDF, which is more robust than the conventional criterion. Numerical results clearly demonstrate the accuracy of the derived asymptotic formulas, and also support our proposed criterion.

Recently, H-bridge pulse width modulation (PWM) micro-stepping motor drivers have been widely used for 3-D printers, robots, and medical instruments. Differently from a simple PWM motor driver circuit, the H-bridge PWM micro-stepping motor driver circuit can generate radio frequency (RF) electromagnetic interference (EMI) noises of up to several hundred MHz frequencies, due to digital interface circuits and a high-performance CPU. For medical instrument systems, the minimization of EMI noises can assure operating safety and greatly reduce the chance of malfunction between instruments. This work proposes a passive-filter configuration-based circuit design for reducing up-to-several-hundred-MHz EMI noises generated from the H-bridge PWM micro-stepping motor driver circuit. More specifically, the proposed RF EMI reduction approach consists of proper passive filter design, shielding in motor wires, and common ground design in the print circuit board. The proposed passive filter configuration design is validated through the overall reduction of EMI noises at RF band. Finally, the proposed EMI reduction approach is tested experientially through a prototype and about 16 dB average reduction of RF EMI noises is demonstrated.

In this paper, we propose a new structure for a compact matched filter bank (MFB) for an optical zero-correlation zone (ZCZ) sequence set with Zcz=2z. The proposed MFB can reduces operation elements such as 2-input adders and delay elements. The number of 2-input adders decrease from O(N2) to O(N log2 N), delay elements decrease from O(N2) to O(N). In addition, the proposed MFBs for the sequence of length 32, 64, 128 and 256 with Zcz=2,4 and 8 are implemented on a field programmable gate array (FPGA). As a result, the numbers of logic elements (LEs) of the proposed MFBs for the sequences with Zcz=2 of length 32, 64, 128 and 256 are suppressed to about 76.2%, 84.2%, 89.7% and 93.4% compared to that of the conventional MFBs, respectively.