The concept of dual pairing vector spaces (DPVS) was introduced by Okamoto and Takashima in 2009, and it has been employed in various applications, functional encryption (FE) including attribute-based encryption (ABE) and inner-product encryption (IPE) as well as attribute-based signatures (ABS), generic conversion from composite-order group based schemes to prime-order group based ones and public-key watermarking. In this paper, we show the concept of DPVS, the major applications to FE and the key techniques employed in these applications. This paper presents them with placing more emphasis on plain and intuitive descriptions than formal preciseness.

This paper proposes a background noise estimation method using an outer product expansion with non-linear filters for ELF (extremely low frequency) electromagnetic (EM) waves. We proposed a novel source separation technique that uses a tensor product expansion. This signal separation technique means that the background noise, which is observed in almost all input signals, can be estimated using a tensor product expansion (TPE) where the absolute error (AE) is used as the error function, which is thus known as TPE-AE. TPE-AE has two problems: the first is that the results of TPE-AE are strongly affected by Gaussian random noise, and the second is that the estimated signal varies widely because of the random search. To solve these problems, an outer product expansion based on a modified trimmed mean (MTM) is proposed in this paper. The results show that this novel technique separates the background noise from the signal more accurately than conventional methods.

This paper shows a method to represent interval functions by using head-tail expressions. The head-tail expressions represent greater-than GT(X:A) functions, less-than LT(X:B) functions, and interval functions IN0(X:A,B) more efficiently than sum-of-products expressions. Let n be the number of bits to represent the largest value in the interval (A,B). This paper proves that a head-tail expression (HT) represents an interval function with at most n words in a ternary content addressable memory (TCAM) realization. It also shows the average numbers of factors to represent interval functions by HTs for up to n=16, which were obtained by a computer simulation. It also conjectures that, for sufficiently large n, the average number of factors to represent n-variable interval functions by HTs is at most 2/3n-5/9. Experimental results also show that, for n≥10, to represent interval functions, HTs require at least 20% fewer factors than MSOPs, on the average.

Much attention has recently been paid to direction of arrival (DOA) estimation using compressed sensing (CS) techniques, which are sparse signal reconstruction methods. In our previous study, we developed a method for estimating the DOAs of multi-band signals that uses CS processing and that is based on the assumption that incident signals have the same complex amplitudes in all the bands. That method has a higher probability of correct estimation than a single-band DOA estimation method using CS. In this paper, we propose novel DOA estimation methods for multi-band signals with frequency characteristics using the Khatri-Rao product. First, we formulate a method that can estimate DOAs of multi-band signals whose phases alone have frequency dependence. Second, we extend the scheme in such a way that we can estimate DOAs of multi-band signals whose amplitudes and phases both depend on frequency. Finally, we evaluate the performance of the proposed methods through computer simulations and reveal the improvement in estimation performance.

A new real-time sound field transmission system is presented. To construct this system, a large listening area needs to be reproduced at not less than a constant height. Additionally, the driving signals of the loudspeakers should be obtained only from received signals of microphones. Wave field reconstruction (WFR) filtering for linear arrays of microphones and loudspeakers is considered to be suitable for this kind of system. An experimental system was developed to show the feasibility of real-time sound field transmission using the WFR filter. Experiments to measure the reproduced sound field and a subjective listening test of sound localization were conducted to evaluate the proposed system. Although the reproduced sound field included several artifacts such as spatial aliasing and faster amplitude decay, the experimental results indicated that the proposed system was able to provide sound localization accuracy for virtual sound sources comparable to that for real sound sources in a large listening area.

Sound field reproduction systems seek to realistically convey 3D spatial audio by re-creating the sound pressure inside a region enclosing the listener. High-order Ambisonics (HOA), a sound field reproduction technology, is notable for defining a scalable encoding format that characterizes the sound field in a system-independent way. Sound fields sampled with a particular microphone array and encoded into the HOA format can be reproduced using any sound presentation device, typically a loudspeaker array, by using a HOA decoder. The HOA encoding format is based on the spherical harmonic decomposition; this makes it easier to design a decoder for large arrays of loudspeakers uniformly distributed over all directions. In practice, it is seldom possible to cover all directions with loudspeakers placed at regular angular intervals. An irregular array, one where the angular separation between adjacent loudspeakers is not constant, does not perform as well as a regular one when reproducing HOA due to the uneven sampling of the spherical harmonics. This paper briefly introduces the techniques used in HOA and advances a new approach to design HOA decoders for irregular loudspeaker arrays. The main difference between conventional methods and our proposal is the use of a new error metric: the radial derivative of the reconstruction error. Minimizing this metric leads to a smooth reproduction, accurate over a larger region than that achieved by conventional HOA decoders. We evaluate our proposal using the computer simulation of two 115-channel loudspeaker arrays: a regular and an irregular one. We find that our proposal results in a larger listening region when used to decode HOA for reproduction using the irregular array. On the other hand, applying our method matches the high-quality reproduction that can be attained with the regular array and conventional HOA decoders.

Binaural reproduction is one of the promising approaches to present a highly realistic virtual auditory space to a listener. Generally, binaural signals are reproduced using a set of headphones that leads to a simple implementation of such a system. In contrast, binaural signals can be presented to a listener using a technique called “transaural reproduction” which employs a few loudspeakers with crosstalk cancellation for compensating acoustic transmissions from the loudspeakers to both ears of the listener. The major advantage of transaural reproduction is that a listener is able to experience binaural reproduction without wearing any device. This leads to a more natural listening environment. However, in transaural reproduction, the listener is required to be still within a very narrow sweet spot because the crosstalk canceller is very sensitive to the listener's head position and orientation. To solve this problem, dynamic transaural systems have been developed by utilizing contact type head tracking. This paper introduces the development of a dynamic transaural system with non-contact head tracking which releases the listener from any attachment, thereby preserving the advantage of transaural reproduction. Experimental results revealed that sound images presented in the horizontal and median planes were localized more accurately when the system tracked the listener's head rotation than when the listeners did not rotate their heads or when the system did not track the listener's head rotation. These results demonstrate that the system works effectively and correctly with the listener's head rotation.

A queue layout of a graph G consists of a linear order of its vertices, and a partition of its edges into queues, such that no two edges in the same queue are nested. The queuenumber qn(G) is the minimum number of queues required in a queue layout of G. The Cartesian product of two graphs G1 = (V1,E1) and G2 = (V2,E2), denoted by G1 × G2, is the graph with {:v1 ∈ V1 and v2 ∈ V2} as its vertex set and an edge (,) belongs to G1×G2 if and only if either (u1,v1) ∈ E1 and u2 = v2 or (u2,v2) ∈ E2 and u1 = v1. Let Tk1,k2,...,kn denote the n-dimensional toroidal grid defined by the Cartesian product of n cycles with varied lengths, i.e., Tk1,k2,...,kn = Ck1 × Ck2 × … × Ckn, where Cki is a cycle of length ki ≥ 3. If k1 = k2 = … = kn = k, the graph is also called the k-ary n-cube and is denoted by Qnk. In this paper, we deal with queue layouts of toroidal grids and show the following bound: qn(Tk1,k2,...,kn) ≤ 2n-2 if n ≥ 2 and ki ≥ 3 for all i = 1,2,...,n. In particular, for n = 2 and k1,k2 ≥ 3, we acquire qn(Tk1,k2) = 2. Recently, Pai et al. (Inform. Process. Lett. 110 (2009) pp.50-56) showed that qn(Qnk) ≤ 2n-1 if n ≥1 and k ≥9. Thus, our result improves the bound of qn(Qnk) when n ≥2 and k ≥9.

One of the technological innovations that has enabled the VLSI semiconductor industry to reduce the transistor size, increase the number of transistors per die, and also follow Moore's law year after year is the fact that an equivalent yield and equivalent testing quality have been ensured for the same die size. This has contributed to reducing the economically optimum production cost (production cost per component) as advocated by Moore. In this paper, we will verify Moore's law using actual values from VLSI manufacturing sites while introducing some of the technical progress that occurred from 1970 to 2010.

In this letter, we present a radix-R regular interconnection pattern family of factorizations for the WHT-FFT with identical stage-to-stage interconnection pattern in a unified form, where R is any power of 2. This family of algorithms has identical sparse matrix factorization in each stage and can be implemented in a merged butterfly structure, which conduce to regular and efficient memory managing scalable to high radices. And in each stage, the butterflies with same twiddle factor set are aggregated together, which can reduce the twiddle factor evaluations or accesses to the lookup table. The kinds of factorization can also be extended to FFT, WHT and SCHT with identical stage-to-stage interconnection pattern.

With the distributed data mining technique having been widely used in a variety of fields, the privacy preserving issue of sensitive data has attracted more and more attention in recent years. Our major concern over privacy preserving in distributed data mining is the accuracy of the data mining results while privacy preserving is ensured. Corresponding to the horizontally partitioned data, this paper presents a new hybrid algorithm for privacy preserving distributed data mining. The main idea of the algorithm is to combine the method of random orthogonal matrix transformation with the proposed secure multi-party protocol of matrix product to achieve zero loss of accuracy in most data mining implementations.

Ocean surface current radar is a Doppler radar to observe oceanographic information using the Bragg scattering resonance mechanism. In this paper, we consider angular resolution improvement of the radar. The radar employs an antenna array with FMICW operation, then it can resolve angular distribution by Digital Beam Forming (DBF) and distance by Fourier transform of the beat signal obtained by the FMICW radar. In order to obtain sufficient angular resolution, large array length or aperture with increasing the number of elements is needed, that is often difficult to realize in the HF/VHF ocean surface current radar. In this paper we propose to apply the Khatri-Rao (KR) product array processing to the radar. To verify effectiveness of the KR product array processing in angular resolution enhancement for the ocean surface current radar, we apply the KR product array to actual experimental data set of the radar, and show that the method is available to angular resolution enhancement and Doppler spectrum improvement.

In this paper, we study on direction-of-arrival (DOA) estimation error reduction by Khatri-Rao (KR) product extended array in the presence of correlated waves. Recently, a simple array signal processing technique called KR product extended array has been proposed. By using the technique, degrees-of-freedom of an array can be easily increased. However, DOA estimation accuracy deteriorates when correlated or coherent waves arrive. Such highly correlated waves often arrive for radar application, hence error reduction technique has been desired. Therefore, in this paper, we propose a new method for error reduction preprocessing scheme by using N-th root of matrix. The N-th root of matrix has a similar effect to the spatial smoothing preprocessing for highly correlated signals. As a result, DOA estimation error due to signal correlation will be reduced. The optimal order of N depends on the data itself. In this paper, a simple iterative method to obtain adaptive N is also proposed. Computer simulation results are provided to show performance of the proposed method.

Microwaves have typically been used for communications and radar, but nowadays are given much attention to energy transfer applications. This paper describes microwave power transfer from a satellite to Earth that is visualized as a solar power satellite system (SPSS). After the system configuration is explained, unique engineering features are presented. Then, some contributions made by Japanese community are introduced, focusing on microwave and antenna engineering. As SPSS will handle high power levels at microwave frequency, and so components should be mass-produced to reduce the cost, then we need to shift our paradigm on the technology involved. Finally, the roadmap to a commercial SPSS is discussed.

First, this paper derives the prefix sum-of-products expression (PreSOP) and the number of products in a PreSOP for an interval function. Second, it derives Ψ(n,τp), the number of n-variable interval functions that can be represented with τp products. Finally, it shows that more than 99.9% of the n-variable interval functions can be represented with ⌈ n - 1 ⌉ products, when n is sufficiently large. These results are useful for a fast PreSOP generator and for estimating the size of ternary content addressable memories (TCAMs) for packet classification.

NTRU is a public key cryptosystem based on hard problems over lattices. In this paper, we present efficient methods for convolution product computation which is a dominant operation of NTRU. The new methods are based on the observation that repeating patterns in coefficients of an NTRU polynomial can be used for the construction of look-up tables, which is a similar approach to the sliding window methods for exponentiation. We provide efficient convolution algorithms to implement this idea, and we make a comprehensive analysis of the complexity of the new algorithms. We also give software implementations over a Pentium IV CPU, a MICAz mote, and a CUDA-based GPGPU platform. According to our analyses and experimental results, the new algorithms speed up the NTRU encryption and decryption operations by up to 41%.

Product return is a critical but controversial issue. To deal with such a vague return problem, businesses must improve their information transparency in order to administrate the product return behaviour of their end users. This study proposes an intelligent return administration expert system (iRAES) to provide product return forecasting and decision support for returned product administration. The iRAES consists of two intelligent agents that adopt a hybrid data mining algorithm. The return diagnosis agent generates different alarms for certain types of product return, based on forecasts of the return possibility. The return recommender agent is implemented on the basis of case-based reasoning, and provides the return centre clerk with a recommendation for returned product administration. We present a 3C-iShop scenario to demonstrate the feasibility and efficiency of the iRAES architecture. Our experiments identify a particularly interesting return, for which iRAES generates a recommendation for returned product administration. On average, iRAES decreases the effort required to generate a recommendation by 70% compared to previous return administration systems, and improves performance via return decision support by 37%. iRAES is designed to accelerate product return administration, and improve the performance of product return knowledge management.

This paper proposes an inner-product encryption (IPE) scheme, which achieves selectively fully-attribute-hiding security in the standard model almost tightly reduced from the decisional linear (DLIN) assumption, and whose ciphertext is almost the shortest among the existing (weakly/fully) attribute-hiding IPE schemes, i.e., it consists of n+4 elements of G and 1 element of GT for a prime-order symmetric bilinear group (G, GT), where n is the dimension of attribute/predicate vectors. We also present a variant of the proposed IPE scheme that enjoys shorter public and secret keys with preserving the security. A hierarchical IPE (HIPE) scheme can be realized that has short ciphertexts and selectively fully-attribute-hiding security almost tightly reduced from the DLIN assumption.

A low-cost and low-power via-programmable structured ASIC architecture named “VPEX3” and a VPEX3-specific CAD system are developed. In the VPEX3 architecture, which is an improved version of the old VPEX and VPEX2 architectures, an arbitrary logic function including sequential logic can be programmed by three via layers. The logic elements (LEs) of VPEX3 are 60% smaller than those of the previous VPEX2, which can be programmed by two via layers. In this paper, we describe a global architecture named Logic Array Block (LAB) composed of LE matrices. The clock lines are buffered in the buffering region on the left and right sides of LAB. Next, a VPEX3-specific CAD system utilizing an academic placement tool named “CAPO” and the “FGR” global router is developed. Since these tools are originally designed for ASICs, we developed CAD tools for supporting a structured ASIC architecture. In particular, we developed a detailed router that assigns via positions on the via-programmable routing fabric. Our CAD system successfully converts the HDL design to GDS-II data format including via-1, 2, 3 layouts, and the successful verification of LVS and DRC on GDSII is achieved. The performance of the VPEX3 architecture and the CAD system is evaluated using ISCAS benchmark circuits. The developed CAD system is used to successfully design a test chip composed of 130110 LEs.

In recent years, user-supplied reviews have increased to become widely prevalent on many websites. Some reviewers (users who comment on items) provide valuable information. Others provide information many people already know. Our goal is to identify credible reviewers who provide valuable information. Two methods can be used to measure reviewer credibility: assessing reviewers based on the content of reviews that they have written in the past and assessing reviewers based on their review histories. By comparing these methods, we aim at obtaining knowledge to determine which method is most useful for identifying credible reviewers. Additionally, many features have been proposed for assessing reviews or reviewers in the previous methods, but they have not been compared. We compare these attributes and clarify what kinds of attribute are useful for identifying credible reviewers.