This work presents a two-stage ordinal optimization theory-based approach for solving the throughput maximization problems with power constraints of sub-carrier assignment and power allocation in multi-user orthogonal frequency division multiplexing uplink systems. In the first stage, a crude but efficient model is employed to evaluate the performance of a sub-carrier assignment pattern and the genetic algorithm is used to search through the huge solution space. In the second stage, an exact model is employed to evaluate s best sub-carrier assignment patterns obtained in stage 1 and form the select subset. Finally, the best one of the select subset is the good enough solution that we seek. Via numerous tests, this work demonstrates the efficiency of the proposed algorithm and compares it with those of other heuristic methods.

This paper presents a general architecture for designing efficient reverse converters based on the moduli set {2α, 22β+1-1, 2β-1}, where β < α ≤ 2β, by using a parallel implementation of mixed-radix conversion (MRC) algorithm. The moduli set {2α, 22β+1-1, 2β-1} is free from modulo (2k+1)-type which can result in an efficient arithmetic unit for residue number system (RNS). The values of α and β can be selected to provide the required dynamic range (DR) and also to adjust the desired equilibrium between moduli bit-width. The simple multiplicative inverses of the proposed moduli set and also using novel techniques to simplify conversion equations lead to a low-complexity and high-performance general reverse converter architecture that can be used to support different DRs. Moreover, due to the current importance of the 5n-bit DR moduli sets, we also introduced the moduli set {22n, 22n+1-1, 2n-1} which is a special case of the general set {2α, 22β+1-1, 2β-1}, where α=2n and β=n. The converter for this special set is derived from the presented general architecture with higher speed than the fastest state-of-the-art reverse converter which has been designed for the 5n-bit DR moduli set {22n, 22n+1-1, 2n-1}. Furthermore, theoretical and FPGA implementation results show that the proposed reverse converter for moduli set {22n, 22n+1-1, 2n-1} results in considerable improvement in conversion delay with less hardware requirements compared to other works with similar DR.

This paper proposes a new approach for the joint processing of signal detection and channel estimation based on the expectation-maximization (EM) algorithm in orthogonal frequency division multiplexing (OFDM) mobile communications. Conventional schemes based on the EM algorithm estimate a channel impulse response using Kalman filter, and employ the random walk model or the first-order autoregressive (AR) model to derive the process equation for the filter. Since these models assume that the time-variation of the impulse response is white noise without considering any autocorrelation property, the accuracy of the channel estimation deteriorates under fast-fading conditions, resulting in an increased packet error rate (PER). To improve the accuracy of the estimation of fast-fading channels, the proposed scheme employs a differential model that allows the correlated time-variation to be considered by introducing the first- and higher-order time differentials of the channel impulse response. In addition, this paper derives a forward recursive form of the channel estimation along both the frequency and time axes in order to reduce the computational complexity. Computer simulations of channels under fast multipath fading conditions demonstrate that the proposed method is superior in PER to the conventional schemes that employ the random walk model.

Careful inspection of efficiency in a DC-DC converter and its dependence on different parameters have been key concerns for power electronic specialists for a long time ago. Although extensive research has been done on the estimation of power loss for different components in a DC-DC converter separately, there isn't any comprehensive study regarding power loss analysis in a DC-DC converter. In this research, detailed description and necessary considerations in order to analyze the power loss of all components in a Push-Pull DC-DC converter are presented. Push-Pull topology is the best choice for investigating efficiency issues, since it exhibits all different types of power loss that are usually encountered in DC-DC converters. This research proposes and verifies appropriate power loss models for all components in a DC-DC converter that dissipate power. For this purpose, conduction and switching loss models of all the relevant components are fully developed. The related equations are implemented in MATLAB environment to simulate all possible causes of power loss in the converter. In order to provide a test bed for evaluation of the proposed loss models and the converter efficiency, a 50 W Push-Pull DC-DC converter was designed and implemented. The experimental results are in full accordance with the simulation results in different input voltages, load conditions and switching frequencies. It was finally shown that the proposed models accurately estimate the DC-DC converter's efficiency.

To further suppress the multiple-access interference (MAI) in frequency-hopping multiple-access (FHMA) system, a novel kind of FH sequence set named as no-hit-zone (NHZ) sequence, is proposed for an FHMA system with M-ary FSK modulation (MFSK/FHMA) in this paper. Expressions for the decision variables are derived for the asynchronous MFSK/FHMA system with NHZ sequence set (MFSK/FHMA-NHZ) under a slow Rayleigh-fading channel model. For the special case of M=2, accurate analytic bit error rate (BER) is derived as a function of maximum relative delay D and the number of users K by a characteristic function method. The theoretical results validated by Monte Carlo simulations are used to investigate the dependence of the average BER on D and K. Comparison with the MFSK/FHMA system with Markov hit pattern (MFSK/FHMA-Markov) shows that MFSK/FHMA-NHZ system performs better than Markov hit pattern system as long as D is restricted in a certain range and further, the gain in the performance increases with increase in the value of K.

In bistatic radar, it is important to suppress the undesired signals such as the direct propagated signal from transmitter and its multipath components. Conventionally, some suppression methods have been proposed. They are categorized into the method using a feedback system and the method which subtracts the replicas of the undesired signals. The former method may have the problem on the convergence of the suppression performance. The latter method requires the precise delay times of the undesired signals. In this paper we propose a new method to detect the target in digital terrestrial TV-based bistatic radar which is based on orthogonal frequency division multiplexing (OFDM), without any information on the undesired signals' delay times. In the proposed method, we adapt a scheme based on maximum signal to noise ratio (MSN) algorithm, which makes signal to interference plus noise ratio (SINR) maximum for the desired signal component. The maximum sensitivity is steered so as to match the path that exhibits the delay which relates to the target position, as if the search beam is steered along the direction in array signal processing. In the proposed method, "nulls" are also formed for other delay components to be suppressed simultaneously. In the frequency domain, the carrier components of the scattered signal divided by those of the reference signal indicate the delays caused by scattering. We call these divided carrier components "normalized received signal." The steered sensitivity and nulls are created by the weight which is applied to the normalized received signal in the frequency domain. We obtain the method to estimate the weight to achieve the maximum SINR in the delay estimation which also includes the compensation for the reduction of the weight's length caused by decorrelation among the delay components. The simulation results show that our proposed method without any information on the undesired signal's delays provides sufficient detection performance for the typical target compared to the conventional one.

This paper proposes an iterative peak power reduction method with adaptive intermediary over-sampling which uses the necessary minimum bandwidth according to iteration number for wireless OFDMA systems. The required bandwidth to each iteration number is evaluated by computer simulation, and over-sampling numbers in iterative processing are controlled by using the simulation results. The results show that the required bandwidth is 1.6, 2.0, and 2.7 times of the used signal bandwidth at the iteration number of 1, 2, and 3, respectively. The proposed adaptive over-sampling method can reduce its multiplication number by 13%.

The purpose of this work is to synthesize a three-dimension C60 polymer using photo-polymerization method. The used pristine materials were C60 precipitates prepared by a liquid-liquid interfacial precipitation (LLIP) method. The prepared LLIP material was set in the vacuum and was compressed in the anvil with the pressure of 600 MPa or 7 GPa. The 4th harmonics FEL with the wavelength of 500 nm was irradiated with macro-pulses (the pulse width of 20 µs) containing very short micro-pulses (the pulse width of 200 fs). The Raman Ag(2) peak of C60 molecules in the vicinity of 1469 cm-1 becomes broad and shifts to the lower energy region as proceeding of polymerization. Under high pressure and/or FEL irradiation the LLIP crystal revealed the large red-shift and the increment of the half width of the Raman Ag(2) peak. Furthermore the LLIP crystal mixture with iodine revealed the more distinctive red-shift, ca.13cm-1 because of highly packing of C60 molecules. The C60 molecular accession by LLIP process and/or the photo-assisted hole-doping from iodine were promising conditions to promote the photo-polymerization effectively.

In situ observation of the adsorption process and the states of cytochrome c on glass/solution interfaces, and the functionality of the reduction reaction of adsorbed cytochorome c were performed by using slab optical waveguide (SOWG) spectroscopy. The peak position of the absorption band of cytochorome c adsorbed on a bare glass surface was almost the same as that of that in solution. The cytochorome c adsorbed on glass/solution interface was reduced by sodium dithionite solution. The adsorbed cytochorome c was still maintained its functionality after immobilization.

This paper describes a technique for reconstructing dynamic scene geometry using a handheld video projector-camera system and a single checkerboard image as a structured light pattern. The proposed technique automatically recognizes a dense checkerboard pattern under dynamic conditions. The pattern-recognition process is adaptive to different light conditions and an object's color, thereby avoiding the need to set threshold values manually for different objects when the scanning device is moving. We also propose a technique to find corresponding positions for the checkerboard pattern, when displayed by a projector, without needing any position-encoding techniques. The correspondence matching process is based on epipolar geometry, enabling the checkerboard pattern to be matched even if parts of it are occluded. By using a dense checkerboard pattern, we can construct a handheld projector-camera system that can acquire the geometry of objects in real time, and we have verified the feasibility of the proposed techniques.

Over the recent years, a great deal of effort has been made to estimate age from face images. It has been reported that age can be accurately estimated under controlled environment such as frontal faces, no expression, and static lighting conditions. However, it is not straightforward to achieve the same accuracy level in a real-world environment due to considerable variations in camera settings, facial poses, and illumination conditions. In this paper, we apply a recently proposed machine learning technique called covariate shift adaptation to alleviating lighting condition change between laboratory and practical environment. Through real-world age estimation experiments, we demonstrate the usefulness of our proposed method.

Ad Hoc Routing (AHR) was proposed to replace optimal routing in cluster-based multihop networks since it offers lower implementation complexity. However, this complexity reduction comes at the cost of an increase in the required transmission power. In addition, when the conventional distributed relay selection is applied to implement AHR, another increase in the required transmission power occurs due to the receiver selection error. In this paper, Ad Hoc Cooperative Routing (AHCR) that integrates the cooperative transmission with AHR is presented to reduce the difference between the required transmission power of AHR and that of optimal routing. Besides, Distributed Ad Hoc Cooperative Routing (DAHCR) scheme 1 that combines the cooperative transmission with AHR is proposed to reduce the difference between the required transmission power of DAHR and that of AHR. We then address the problem of DAHCR scheme 1 and propose DAHCR scheme 2. Simulation results show that the required transmission power of AHCR and DAHCR scheme 1 is less than that of AHR and DAHR, respectively. In addition, DAHCR scheme 2 further reduces the required transmission power of DAHCR scheme 1. On the other hand, DAHCR scheme 1 increases the complexity by 43% compared to DAHR. Besides, DAHCR scheme 2 increases the complexity by 1.97% compared to DAHCR scheme 1.

We examined the characteristics of fiber fuse propagation in hole-assisted fibers (HAF). The fiber fuse propagated in the same way as in conventional single-mode fiber (SMF) when the diameter of an inscribed circle linking the air holes (c) was much larger than the diameter of the melted area (Dmelted). The melted area is caused by fiber fuse propagation and Dmelted is assumed to be almost the same size as the plasma. However, when c was much smaller than Dmelted, the fiber fuse did not propagate in HAF with input powers above 15 W at 1480 and 1550 nm. This result indicates that the threshold power of fiber fuse propagation in HAF can be at least 10 times larger than that in conventional SMF in the optical communication band. We also observed the dynamics of fiber fuse termination at a splice point between HAF and a conventional fiber by using a high-speed camera, when c was much smaller than Dmelted. We consider that the reduction in gas density caused by the air holes results in fiber fuse termination. When c was almost the same as Dmelted, we observed a new propagation mode and its dynamics for a fiber fuse with a damage track whose period was approximately 30 times longer than that in conventional SMF. We also made the first observation of a new threshold power (upper threshold) for a fiber fuse.

The active shape model (ASM) has been widely adopted by automated bone segmentation approaches for radiographic images. In radiographic images of the distal radius, multiple edges are often observed in the near vicinity of the bone, typically caused by the presence of thin soft tissue. The presence of multiple edges decreases the segmentation accuracy when segmenting the distal radius using ASM. In this paper, we propose an enhanced distal radius segmentation method that makes use of a modified version of ASM, reducing the number of segmentation errors. To mitigate segmentation errors, the proposed method emphasizes the presence of the bone edge and downplays the presence of a soft tissue edge by making use of Dual energy X-ray absorptiometry (DXA). To verify the effectiveness of the proposed segmentation method, experiments were performed with 30 distal radius patient images. For the images used, compared to ASM-based segmentation, the proposed method improves the segmentation accuracy with 47.4% (from 0.974 mm to 0.512 mm).

Precise estimation of data distribution with a small number of sample patterns is an important and challenging problem in the field of statistical pattern recognition. In this paper, we propose a novel method for estimating multimodal data distribution based on the Gaussian mixture model. In the proposed method, multiple random vectors are generated after classifying the elements of the feature vector into subsets so that there is no correlation between any pair of subsets. The Gaussian mixture model for each subset is then constructed independently. As a result, the constructed model is represented as the product of the Gaussian mixture models of marginal distributions. To make the classification of the elements effective, a graph cut technique is used for rearranging the elements of the feature vectors to gather elements with a high correlation into the same subset. The proposed method is applied to a character recognition problem that requires high-dimensional feature vectors. Experiments with a public handwritten digit database show that the proposed method improves the accuracy of classification. In addition, the effect of classifying the elements of the feature vectors is shown by visualizing the distribution.

In this letter, we study the performance of multi-antenna relay networks with limited feedback beamforming in decode-and-forward (DF) relaying. Closed-form expression for both outage probability and symbol error rate are derived by using the moment generation function (MGF) of the combined signal-to-noise ratio (SNR) at the destination. Subjected to a total power constraint, we also explore adaptive power allocation between source and relay to optimize the performance. Simulations are given to verify the correctness of our theoretical derivations. Results show that the proposed adaptive power allocation solution significantly outperforms the uniform power allocation method.

Background subtraction is widely used in detecting moving objects; however, changing illumination conditions, color similarity, and real-time performance remain important problems. In this paper, we introduce a sequential method for adaptively estimating background components using Kalman filters, and a novel method for detecting objects using margined sign correlation (MSC). By applying MSC to our adaptive background model, the proposed system can perform object detection robustly and accurately. The proposed method is suitable for implementation on a graphics processing unit (GPU) and as such, the system realizes real-time performance efficiently. Experimental results demonstrate the performance of the proposed system.

An interactive support system for image quality enhancement to adjust display equipments according to the user's own subjectivity is developed. Interactive support system for image quality enhancement enable the parameters based on user's preference to be derived by only selecting user's preference images without adjusting image quality parameters directly. In the interactive support system for image quality enhancement, the more the number of parameters is, the more effective this system is. In this paper, lightness, color and sharpness are used as the image quality parameters and the images are enhanced by increasing the number of parameters. Shape of tone curve is controlled by two image quality adjustment parameters for lightness enhancement. Images are enhanced using two image quality adjustment parameters for color enhancement. The two parameters are controlled in L* a* b* color space. Degree and coarseness of image sharpness enhancement are adjusted by controlling a radius of mask of smoothing filter and weight of adding. To confirm the effectiveness of the proposed method, the image quality and derivation time of the proposed method are compared with a manual adjustment method.

A new image watermarking scheme is presented to achieve high capacity information hiding and geometric invariance simultaneously. Visually salient region is introduced into watermark synchronization. The saliency value of a region is used as the quantitative measure of robustness, based on which the idea of locally most salient region (LMSR) is proposed to generate the disjoint invariant regions. A meaningful binary watermark is then encoded using Chinese Remainder Theorem (CRT) in transform domain. Simulation results and comparisons demonstrate the effectiveness of the proposed scheme.

The search for lightweight authentication protocols suitable for low-cost RFID tags constitutes an active and challenging research area. In this context, a family of protocols based on the LPN problem has been proposed: the so-called HB-family. Despite the rich literature regarding the cryptanalysis of these protocols, there are no published results about the impact of fault analysis over them. The purpose of this paper is to fill this gap by presenting fault analytic methods against a prominent member of the HB-family: HB+ protocol. We demonstrate that the fault analysis model can lead to a flexible and effective attack against HB-like protocols, posing a serious threat over them.