Analogy-based software effort estimation has gained a considerable amount of attention in current research and practice. Its excellent estimation accuracy relies on its solution adaptation stage, where an effort estimate is produced from similar past projects. This study proposes a solution adaptation technique named LSA-X that introduces an approach to exploit the potential of productivity factors, i.e., project variables with a high correlation with software productivity, in the solution adaptation stage. The LSA-X technique tailors the exploitation of the productivity factors with a procedure based on the Linear Size Adaptation (LSA) technique. The results, based on 19 datasets show that in circumstances where a dataset exhibits a high correlation coefficient between productivity and a related factor (r≥0.30), the proposed LSA-X technique statistically outperformed (95% confidence) the other 8 commonly used techniques compared in this study. In other circumstances, our results suggest using any linear adaptation technique based on software size to compensate for the limitations of the LSA-X technique.

Remote Access Trojans (RAT) is a spyware which can steal the confidential information from a target organization. The detection of RATs becomes more and more difficult because of targeted attacks, since the victim usually cannot realize that he/she is being attacked. After RAT's intrusion, the attacker can monitor and control the victim's PC remotely, to wait for an opportunity to steal the confidential information. As this situation, the main issue we face now is how to prevent confidential information being leaked back to the attacker. Although there are many existing approaches about RAT detection, there still remain two challenges: to detect RAT sessions as early as possible, and to distinguish them from the normal applications with a high accuracy. In this paper, we propose a novel approach to detect RAT sessions by their network behavior during the early stage of communication. The early stage is defined as a short period of time at communication's beginning; it also can be seen as the preparation period of the communication. We extract network behavior features from this period, to differentiate RAT sessions and normal sessions. For the implementation and evaluation, we use machine learning techniques with 5 algorithms and K-Fold cross-validation. As the results, our approach could detect RAT sessions in the communication's early stage with the accuracy over 96% together with the FNR of 10% by Random Forest algorithm.

This paper proposes the first (practical) inner product encryption (IPE) scheme that is adaptively secure and fully attribute-hiding (attribute-hiding in the sense of the definition by Katz, Sahai and Waters), while the existing (practical) IPE schemes are either fully attribute-hiding but selectively secure or adaptively secure but weakly attribute-hiding. The proposed IPE scheme is proven to be adaptively secure and fully attribute-hiding under the decisional linear assumption in the standard model. The IPE scheme is comparably as efficient as the existing (practical) attribute-hiding IPE schemes. We also present a variant of the proposed IPE scheme with the same security that achieves shorter public and secret keys. A hierarchical IPE scheme can be constructed that is also adaptively secure and fully attribute-hiding under the same assumption. In this paper, we extend the dual system encryption technique by Waters into a more general manner, in which new forms of ciphertext and secret keys are employed and new types of information theoretical tricks are introduced along with several forms of computational reduction.

We focus on the feature transform approach as one methodology for biometric template protection, where the template consists of the features extracted from the biometric trait. This study considers some properties of the unitary (including orthogonal) transform-based template protection in particular. It is known that the Euclidean distance between the templates protected by a unitary transform is the same as that between original (non-protected) ones as a property. In this study, moreover, it is shown that it provides the same results in l2-norm minimization problems as those of original templates. This means that there is no degradation of recognition performance in authentication systems using l2-norm minimization. Therefore, the protected templates can be reissued multiple times without original templates. In addition, a DFT-based template protection scheme is proposed as an unitary transform-based one. The proposed scheme enables to efficiently generate protected templates by the FFT, in addition to the useful properties. It is also applied to face recognition experiments to evaluate the effectiveness.

Recently, many neural networks have been proposed for radar sea clutter suppression. However, they have poor performance under the condition of low signal to interference plus noise ratio (SINR). In this letter, we put forward a novel method to detect a small target embedded in sea clutter based on an optimal filter. The proposed method keeps the energy in the frequency cell under test (FCUT) invariant, at the same time, it minimizes other frequency signals. Finally, detect target by judging the output SINR of every frequency cell. Compared with the neural networks, the algorithm proposed can detect under lower SINR. Using real-life radar data, we show that our method can detect the target effectively when the SINR is higher than -39dB which is 23dB lower than that needed by the neural networks.

Explicit evaluation of the rate-distortion function has rarely been achieved when it is strictly greater than its Shannon lower bound since it requires to identify the support of the optimal reconstruction distribution. In this paper, we consider the rate-distortion function for the distortion measure defined by an ε-insensitive loss function. We first present the Shannon lower bound applicable to any source distribution with finite differential entropy. Then, focusing on the Laplacian and Gaussian sources, we prove that the rate-distortion functions of these sources are strictly greater than their Shannon lower bounds and obtain upper bounds for the rate-distortion functions. Small distortion limit and numerical evaluation of the bounds suggest that the Shannon lower bound provides a good approximation to the rate-distortion function for the ε-insensitive distortion measure. By using the derived bounds, we examine the performance of a scalar quantizer. Furthermore, we discuss variants and extensions of the ε-insensitive distortion measure and obtain lower and upper bounds for the rate-distortion function.

Multiple-input multiple-output (MIMO) technology is a useful means of achieving the higher data rates needed in the latest wireless devices. However, weighting calculations for MIMO transmission become complicated when there are a large number of antennas. Thus, developing a simpler way to transmit and receive multiple streams is an idea worth considering. With this in mind, we propose a spatial division method using orthogonal directivities formed by using higher order modes of rectangular microstrip antennas. Each of them is formed by one antenna element so that channels are orthogonalized only by antennas. We verify antenna radiation characteristics by using higher order mode microstrip antennas and confirm that orthogonal directivities are obtained with them. Measurement of two stream transmission reveals that the method achieves almost the same channel capacity as that of an eigenmode-beamforming method because of the high multiplexing gain it achieves.

The characteristic basis function method using improved primary characteristic basis functions (IP-CBFM) has been proposed as a technique for high-precision analysis of monostatic radar cross section (RCS) of a scattering field in a specific coordinate plane. IP-CBFM is a method which reduces the number of CBF necessary to express a current distribution by combining secondary CBF calculated for each block of the scatterer with the primary CBF to form a single improved primary CBF (IP-CBF). When the proposed technique was evaluated by calculating the monostatic RCS of a perfect electric conductor plate and cylinder, it was found that solutions corresponding well with analysis results from conventional CBFM can be obtained from small-scale matrix equations.

Purchase behavior prediction is one of the most important issues for the precision marketing of e-commerce companies. This Letter presents our solution to the purchase behavior prediction problem in E-commerce, specifically the task of Big Data Contest of China Computer Federation in 2014. The goal of this task is to predict which users will have the purchase behavior based on users' historical data. The traditional methods of recommendation encounter two crucial problems in this scenario. First, this task just predicts which users will have the purchase behavior, rather than which items should be recommended to which users. Second, the large-scale dataset poses a big challenge for building the empirical model. Feature engineering and Factorization Model shed some light on these problems. We propose to use Factorization Machines model based on the multiple classes and high dimensions of feature engineering. Experimental results on a real-world dataset demonstrate the advantages of our proposed method.

This paper proposes a method of watermarking for digital audio signals based on adaptive phase modulation. Audio signals are usually non-stationary, i.e., their own characteristics are time-variant. The features for watermarking are usually not selected by combining the principle of variability, which affects the performance of the whole watermarking system. The proposed method embeds a watermark into an audio signal by adaptively modulating its phase with the watermark using IIR all-pass filters. The frequency location of the pole-zero of an IIR all-pass filter that characterizes the transfer function of the filter is adapted on the basis of signal power distribution on sub-bands in a magnitude spectrum domain. The pole-zero locations are adapted so that the phase modulation produces slight distortion in watermarked signals to achieve the best sound quality. The experimental results show that the proposed method could embed inaudible watermarks into various kinds of audio signals and correctly detect watermarks without the aid of original signals. A reasonable trade-off between inaudibility and robustness could be obtained by balancing the phase modulation scheme. The proposed method can embed a watermark into audio signals up to 100 bits per second with 99% accuracy and 6 bits per second with 94.3% accuracy in the cases of no attack and attacks, respectively.

The RCS of a radar target is an important factor related with the radar performance such as detection, tracking and classification. When dealing with the design of 26/79GHz automotive surveillance radar system, it is essential to know individual RCS of typical vehicles and pedestrian. However, there are few papers related to the RCS measurement at 26 and 79GHz. In this letter, the RCS measurements of typical vehicles and pedestrian were performed in a large-scale anechoic chamber room and the characteristics are discussed.

This letter proposes a novel post-processing method for self-similarity based super-resolution (SR). Existing back-projection (BP) methods enhance SR images by refining the reconstructed coarse high-frequency (HF) information. However, it causes artifacts due to interpolation and excessively smoothes small HF signals, particularly in texture regions. Motivated by these observations, we propose a novel post-processing method referred to as middle-frequency (MF) based refinement. The proposed method refines the reconstructed HF information in the MF domain rather than in the spatial domain, as in BP. In addition, it does not require an internal interpolation process, so it is free from the side-effects of interpolation. Experimental results show that the proposed algorithm provides superior performance in terms of both the quantity of reproduced HF information and the visual quality.

This paper proposes an analytical, closed-form AC-DC voltage multiplier model and investigates the dependency of output current and input power on circuit and device parameters. The model uses no fitting parameters and a frequency term applicable to both multipliers using diodes and metal-oxide semiconductor field effect transistors (MOSFETs). Analysis enables circuit designers to estimate circuit parameters, such as the number of stages and capacitance per stages, and device parameters such as saturation current (in the case of diodes) or transconductance (in the case of MOSFETs). Comparisons of the proposed model with SPICE simulation results as well as other models are also provided for validation. In addition, design optimizations and the impact of AC power source impedance on output power are also investigated.

The sliding discrete Fourier transform (DFT) is a well-known algorithm for obtaining a few frequency components of the DFT spectrum with a low computational cost. However, the conventional sliding DFT cannot be applied to practical conditions, e.g., using the sine window and the zero-padding DFT, with preserving the computational efficiency. This paper discusses the extension of the sliding DFT to such cases. Expressing the window function by complex sinusoids, a recursive algorithm for computing a frequency component of the DFT spectrum using an arbitrary sinusoidal window function is derived. The algorithm can be easily extended to the zero-padding DFT. Computer simulations using very long signals show the validity of our algorithm.

In this paper, we present a modified image rejection method that uses imbalance compensation techniques for phase and gain in low-intermediate frequency (IF) software-defined radio (SDR) receivers. In low-IF receivers, the image frequency signal interferes with the desired signal owing to the phase and gain imbalances caused by analog devices. Thus, it is difficult to achieve the required image rejection ratio (IRR) of over 60dB without compensation. To solve this problem, we present modified blind compensation techniques based on digital signal processing using a feedback control loop with a practical computation process. The modified method can reduce the complexity when a hardware logic circuit is used, like an FPGA. The simulation and experimental results verify that the modified method achieves an IRR greater than 50-60dB for both the carrier and the modulated waves.

Among several optical devices in integrated optics, the fundamental characteristics of collinear optical switching devices have been studied about optical dielectric waveguides. Conventional waveguide-type acousto-optic (A-O) devices use collinear and longitudinal interactions with mode coupling based on the Bragg condition between optical waves and surface acoustic waves (SAW). Collinear A-O devices of the waveguide-type show sufficient performance for wavelength-selective switching with narrow bandwidths. However, in these collinear A-O devices, interaction time is several microseconds for 10 mm waveguide device length. In A-O devices of optical waveguides using transverse A-O interaction, where SAW propagates transversely to optical wave propagation direction, SAW propagation lengths needed for complete A-O interaction may become 10 µm and interaction time may be several nanoseconds. In this paper, fundamental characteristics of the transverse A-O interaction are studied as an electromagnetic boundary value problem. Refractive indices in optical waveguides induced by A-O effects with SAW are shown by sine functions. Wave field characteristics in periodic structures for transverse directions are analyzed by analytic method of Hill's equations for transverse spectral functions. Electromagnetic fields in regions with periodic structures are discussed by the Mathieu functions and the perturbation method. Dispersion characteristics of A-O eigen modes are studied for wavelengths of optical waves and SAW, with A-O coefficients.

In the development of inter-vehicle communication systems for the prevention of car crashes, it is important to know radio propagation characteristics at blind intersections. In field experiments and numerical simulations to investigate radio propagation characteristics, a half wavelength dipole antenna is assumed to be the wave source in many cases. However, a directivity of car antenna is changed by the effect of both car body and antenna position on car. In this paper, path loss characteristics considering antenna positions on car body at a blind intersection in urban area for inter-vehicle communications using 700MHz band are investigated. Additionally, simplified car models are proposed for the efficient analysis of radio propagation. Here, the hybrid method using both FDTD and ray-tracing methods is used for the radio propagation analysis.

The phenomenon of stochastic resonance (SR) in a mono-threshold-system-based detector (MTD) with additive background noise and multiplicative external noise is investigated. On the basis of maximum a posteriori probability (MAP) criterion, we deal with the binary signal transmission in four scenarios. The performance of the MTD is characterized by the probability of error detection, and the effects of system threshold and noise intensity on detectability are discussed in this paper. Similar to prior studies that focus on additive noises, along with increases in noise intensity, we also observe a non-monotone phenomenon in the multiplicative ways. However, unlike the case with the additive noise, optimal multiplicative noises all tend toward infinity for fixed additive noise intensities. The results of our model are potentially useful for the design of a sensor network and can help one to understand the biological mechanism of synaptic transmission.

We propose an algorithm for the scattering analyses of gratings with various local defects based on the difference-field boundary-element method (DFBEM). In the algorithm, the defect in the grating is partitioned, and the DFBEM is sequentially applied for each defect section. We validate the proposed algorithm by demonstrating its flexibility for various defect topologies for a locally deformed grating.

We deal with the scattering of a plane wave by the end-face of a waveguide system by the numerical method based on the sinc function and calculate the electric field on the end-face. It is shown that the results obtained analytically by the perturbation method are in relatively good agreement with the numerical results.