This paper proposes a dual-conduction class-C VCO for ultra-low supply voltages. Two cross-coupled NMOS pairs with different bias points are employed. These NMOS pairs realize an impulse-like current waveform to improve the phase noise in the low supply conditions. The proposed VCO was implemented in a standard 0.18 µm CMOS technology, which oscillates at a carrier frequency of 4.5 GHz with a 0.2-V supply voltage. The measured phase noise is -104 dBc/Hz@1 MHz-offset with a power consumption of 114 µW, and the FoM is -187 dBc/Hz.

A technique to reduce noise transfer functions (NTF) of switched-capacitor (SC) integrators without changing their signal transfer functions (STF) is proposed. The proposed technique based on a simple reconnection scheme of multiple sampling capacitors. It can be implemented into any SC integrators as long as they have a transfer delay. A design strategy is also given to reduce the effect of parasitic capacitors. An SC integrator with a small total capacitance and a low noise transfer gain based on the proposed technique is also proposed. For a given design example, the total capacitance and the simulated noise transfer gain of the proposed SC integrator are 37% and 90% less than the conventional one.

Using a single-site lightning location technique, a new portable lightning location system is developed. We incorporate an attitude detection technique using inertial sensors to detect an accurate electromagnetic field vector of sferics by palm-sized electromagnetic sensors which can have arbitrary attitude. The present paper describes the concept and the performance of the developed prototype of the portable system.

We present pseudo-preimage attacks on Davis-Meyer mode of reduced rounds of the block ciphers ARIA, Camellia, and Serpent by using Sasaki's framework. They yield preimage or second-preimage attacks on PGV hashing modes. We develop proper initial structures for applying meet-in-the-middle techniques to the block ciphers, by considering their diffusion layers, and propose a method to find matching-check equations for indirect partial matching technique with a binary matrix. These works enable us to attack 5 rounds of ARIA, 7 rounds of Camellia, and 4 rounds of Serpent faster than brute force attack.

Satellite-borne SAR (synthetic aperture radar) is for high-resolution geosurface measurements. Recently, a feature extraction method based on CCD (coherent change detection) was developed, where a slight surface change on the geosurface is detected using the phase relationship between sequential complex SAR images of the same region made at different times. For accurate detection of the surface change, the log-likelihood method has been proposed. This method determines an appropriate threshold for change detection, making use of the phase characteristic of the changed area, and thus enhances the detection probability. However, this and other conventional methods do not seek to proactively employ phase information of the estimated coherence function, and their detection probability is often low, especially in the case that the target has small surface or local uniform changes. To overcome this problem, this paper proposes a novel transformation index that considers the phase difference of the coherence function. Furthermore, we introduce a pre-processing calibration method to compensate the bias error for the coherence phase which resulting mainly from the orbit error of the antenna platform. Finally, the results from numerical simulations and experiment modeling of the geosurface measurement verify the effectiveness of the proposed method, even in situations with low SNR (signal to noise ratio).

We propose preimage attacks against PKC98-Hash and HAS-V. PKC98-Hash is a 160-bit hash function proposed at PKC 1998, and HAS-V, a hash function proposed at SAC 2000, can produce hash values of 128+32k (k=0,1,...,6) bits. These hash functions adopt the Merkle-Damgård and Davies-Meyer constructions. One unique characteristic of these hash functions is that their step functions are not injective with a fixed message. We utilize this property to mount preimage attacks against these hash functions. Note that these attacks can work for an arbitrary number of steps. The best proposed attacks generate preimages of PKC98-Hash and HAS-V-320 in 264 and 2256 compression function computations with negligible memory, respectively. This is the first preimage attack against the full PKC98-Hash function.

This paper deals with the diffraction of a transverse magnetic (TM) plane wave by a perfectly conductive periodic surface by an integral method. However, it is known that a conventional integral method does not work for a critical angle of incidence, because of divergence of a periodic Green's function (integral kernel). To overcome such a divergence difficulty, we introduce an image Green's function which is physically defined as a field radiated from an infinite phased array of dipoles. By use of the image Green's function, it is newly shown that the diffracted field is represented as a sum of radiation from the periodic surface and its image surface. Then, this paper obtains a new image integral equation for the basic surface current, which is solved numerically. A numerical result is illustrated for a very rough sinusoidal surface. Then, it is concluded that the method of image Green's function works practically even at a critical angle of incidence.

An inter-vehicle communication system for the 720 MHz band that is designed to prevent car crashes at intersections has recently been proposed in Japan. This paper presents an analysis of the propagation characteristics of an intersection surrounded by concrete block walls in a residential area. The propagation characteristics were analyzed for the first time using the finite-difference time-domain (FDTD) method. We investigated the influence of wall thickness and source locations on the propagation characteristics. The results of our investigation showed that the most commonly used wall thickness and source locations do not strongly affect propagation loss. Furthermore, we analyzed the power delay profile and delay spread by taking into consideration the structure of the concrete block walls.

An inductorless low noise amplifier (LNA) with active balun for digital TV (DTV) applications is presented. The LNA exploits a noise cancellation technique which allows for simultaneous wide-band impedance matching and low noise design. The matching and amplifier stages in the LNA topology perform single-ended to differential signal conversion with balanced output. The second and third-order nonlinearity of the individual amplifiers as well as the distortion caused by the interaction between the stages are suppressed to achieve high IIP2 and IIP3. A method for intrinsic cancellation of the second-order interaction is employed to reduce the dependence of the IIP3 on the frequency spacing between the interfering signals in the two-tone test of DTV tuners. Fabricated in a 0.18 µm CMOS technology, the LNA core size is 0.21 mm2. Measurements show that the LNA IIP3 and IIP2 are +12 dBm and +21 dBm, respectively. The IIP3 variation is less than 5 dB in the 10 MHz to 200 MHz frequency spacing range. A voltage gain of 14.5 dB and a noise figure below 4 dB are achieved in a frequency range from 100 MHz to 1 GHz. The LNA consumes 11 mA from a 1.8 V supply voltage.

The 2-adic complexity of binary periodic sequences plays an important role in cryptology. In this paper, by means of the usual Fourier transform, we give a simpler form of the upper bound for 2-adic complexity than related result before. For pn-periodic sequences, we discuss the relation between sequences and their Fourier coefficients. Furthermore, based on the relation, we get the lower bound for the number of pn-periodic sequences with given 2-adic complexity.

Constructing a secure and efficient key wrapping scheme is demanding, and the scheme based on a universal hash function and an elementary encryption mode like ECB and CBC modes is potential for a practical use. However, at SAC 2009, Gennaro and Halevi showed that a key wrapping scheme using a universal hash function and ECB mode (a HtECB scheme) is broken, and the security of a scheme based on a universal hash function and CBC mode (a HtCBC scheme) has been left as an open problem. In this paper, we first generalize classical notions of universal and uniform hash functions, and propose a total of four new notions of the keyed hash function. We then prove that HtECB and HtCBC schemes are secure key wrapping schemes if the universal hash function satisfies uniformity and our notions, where the result on the HtCBC scheme gives a partial answer to the open problem. Then we discuss a basic problem of identifying relations between various notions of a keyed hash function, and point out that a monic polynomial hash function satisfies all the new notions.

Undeniable signature, and unpretendable signature schemes have been studied independently. In this paper, efficient schemes which serve as both at the same time are presented. The schemes find their typical application in anonymous auction where the winner cannot deny her bid; nobody can pretend to be the winner; and the anonymity of all losers is preserved. The security of the schemes is proved in the common reference string model under discrete logarithm type assumptions.

Based on Tu-Deng's conjecture and the Tu-Deng function, in 2010, X. Tang et al. proposed a class of Boolean functions in even variables with optimal algebraic degree, very high nonlinearity and optimal algebraic immunity. In this corresponding, we consider the concatenation of Tang's function and another Boolean function, and study its cryptographic properties. With this idea, we propose a class of 1-resilient Boolean functions in odd variables with optimal algebraic degree, good nonlinearity and suboptimal algebraic immunity based on Tu-Deng's conjecture.

The metallic waveguide is one of many effective media for millimeter- and submillimeter-waves because of the advantage of its low-loss nature. This paper describes the fabrication method of PTFE-filled waveguide components with the use of the SR (synchrotron radiation) direct etching process of PTFE, sputter deposition of metal, and electroplating. PTFE is known as a difficult material to process with high precision. However, it has been reported that PTFE microstructures can be fabricated by the direct exposure to SR. First, an iris-coupled waveguide BPF with 5-stage Chebyshev response is designed and fabricated for the Q-band. It is demonstrated that the present process is applicable for the fabrication of the practical components inclusive of narrow patterns. Then, a cruciform 3 dB coupler with air-filled posts is designed and fabricated for the Q-band. Directivity and matched state of the coupler can be realized by “holes” in the dielectric material. The measurement results are also shown.

T-function is a kind of cryptographic function which is shown to be useful in various applications. It is known that any function f on F2n or Z2n automatically deduces a unique polynomial fF ∈ F2n[x] with degree ≤ 2n-1. In this letter, we study an algebraic property of fF while f is a T-function. We prove that for a single cycle T-function f on F2n or Z2n, deg fF=2n-2 which is optimal for a permutation. We also consider a kind of widely used T-function in many cryptographic algorithms, namely the modular addition function Ab(x)=x+b ∈ Z2n[x]. We demonstrate how to calculate deg Ab F from the constant value b. These results can facilitate us to evaluate the immunity of the T-function based cryptosystem against some known attacks such as interpolation attack and integral attack.

Large capacity tags are becoming available to meet the demands of industry, but the UHF RFID protocol is unable to reliably and efficiently read large data sets from tags. First of all, large data sets are not well protected. The tag merely relies on 16-bit CRC for ensuring the validity of up to 4,096-bit user-specific data in EPCglobal C1G2 protocol. Furthermore, the reliability will be even worse if large capacity tags are implemented using semi-active technology which is likely to prevail among sensor-integrated RFID tags. Since semi-active tags greatly alleviate the performance limitation imposed by the turn-on power of the tag chip, backscattering signal of semi-active tags could be a serious challenge for most readers because it is much weaker than signals emitted by passive tags due to longer reading distance. In this paper, Interim CRC is presented to enhance transmission reliability and efficiency when the tag is backscattering a large data set. By taking advantage of Interim CRC, the large data set can be divided into several blocks, and 16-bit checksum is calculated over each block. The tag backscatters all blocks at the first time and only retransmits certain blocks if CRC error occurs in those blocks. The result of simulation shows that the reading error rate can be confined to a preset threshold and the accumulative total of transmitted data are greatly reduced if optimal block size and transmission times are complied with. The simulation also conclusively proves that semi-active tags derive even longer reading range from Interim CRC. In addition, Interim CRC is totally compliant with the EPCglobal C1G2 protocol. It fully makes use of CRC-16 encoder and does not involve any other data encoding schematics and hardware modifications.

The problem of a Gaussian beam that is incident on a plane dielectric interface from a denser dielectric medium to a rarer one and is reflected at the interface has been important research subjects studied by many researchers. In this paper, we have obtained a novel uniform asymptotic solution for reflection and beam shift of the Gaussian beam that is incident on the interface from the denser medium. The uniform asymptotic solution consists of the geometrically reflected beam, the lateral beam if any, and the newly derived transition beam which plays an important role in the transition region near the critical angle of the total reflection. We have confirmed the validity of the uniform asymptotic solution by comparing with the reference solution obtained numerically from the integral representation. We have shown that, in addition to the Goos-Hanchen shift and the angular shift, the Gaussian beam is shifted to either direction by the interference of the geometrically reflected beam and the lateral beam near the critical angle of the total reflection.

This paper discusses the task of human action detection. It requires not only classifying what type the action of interest is, but also finding actions' spatial-temporal locations in a video. The novelty of this paper lies on two significant aspects. One is to introduce a new graph based representation for the search space in a video. The other is to propose a novel sub-volume search method by Minimum Cycle detection. The proposed method has a low computation complexity while maintaining a high action detection accuracy. It is evaluated on two challenging datasets which are captured in cluttered backgrounds. The proposed approach outperforms other state-of-the-art methods in most situations in terms of both Precision-Recall values and running speeds.

In the past few years, discriminant analysis and manifold learning have been widely used in feature extraction. Recently, the sparse representation technique has advanced the development of pattern recognition. In this paper, we combine both discriminant analysis and manifold learning with sparse representation technique and propose a novel feature extraction approach named sparsity preserving embedding with manifold learning and discriminant analysis. It seeks an embedded space, where not only the sparse reconstructive relations among original samples are preserved, but also the manifold and discriminant information of both original sample set and the corresponding reconstructed sample set is maintained. Experimental results on the public AR and FERET face databases show that our approach outperforms relevant methods in recognition performance.

CLEFIA is a 128-bit block cipher proposed by Shirai et al. in 2007. On its saturation attack, Tsunoo et al. reported peculiar saturation characteristics in 2010. They formulated some hypotheses on the existence of the characteristics with no proof. In this paper we have theoretically proved their hypotheses. In their attack scenario, we show that the mod-2 distribution is a code word of Extended Hamming code, and then proof is given by using the property of Hadamard transform.