A flexible and computationally efficient method for spectral analysis of sinusoidal signals using the Basis Pursuit De-Noising (BPDN) is proposed. This method estimates a slotted Auto-Correlation Function (ACF) and computes the spectrum as the sparse representation of the ACF in a dictionary of cosine functions. Simulation results illustrate flexibility and effectiveness of the proposed method.

We have demonstrated switching characteristics in a wavelength switch based on multiple GaInAs/InP quantum wells. It consisted of straight arrayed waveguides with a linearly varying refractive index distribution. The refractive index can be changed via the thermo-optic (TO) effect. Using a Ti/Au thin-film heater to generate the TO effect, we realized four-port switching at four demultiplexed wavelengths. In addition, by changing the structure of the heater from rectangular to triangular, the power consumption for four-port switching was reduced by half.

This work presents a real-time human detection system for VGA (Video Graphics Array, 640480) video, which well suits visual surveillance applications. To achieve high running speed and accuracy, firstly we design multiple fast scalar feature types on the gradient channels, and experimentally identify that NOGCF (Normalized Oriented Gradient Channel Feature) has better performance with Gentle AdaBoost in cascaded classifiers. A confidence measure for cascaded classifiers is developed and utilized in the subsequent tracking stage. Secondly, we propose to use speedup techniques including a detector pyramid for multi-scale detection and channel compression for integral channel calculation respectively. Thirdly, by integrating the detector's discrete detected humans and continuous detection confidence map, we employ a two-layer tracking by detection algorithm for further speedup and accuracy improvement. Compared with other methods, experiments show the system is significantly faster with 20 fps running speed in VGA video and has better accuracy as well.

Recently, there is much concern about the provenance of distributed processes, that is about the documentation of the origin and the processes to produce an object in a distributed system. The provenance has many applications in the forms of medical records, documentation of processes in the computer systems, recording the origin of data in the cloud, and also documentation of human-executed processes. The provenance of distributed processes can be modeled by a directed acyclic graph (DAG) where each node represents an entity, and an edge represents the origin and causal relationship between entities. Without sufficient security mechanisms, the provenance graph suffers from integrity and confidentiality problems, for example changes or deletions of the correct nodes, additions of fake nodes and edges, and unauthorized accesses to the sensitive nodes and edges. In this paper, we propose an integrity mechanism for provenance graph using the digital signature involving three parties: the process executors who are responsible in the nodes' creation, a provenance owner that records the nodes to the provenance store, and a trusted party that we call the Trusted Counter Server (TCS) that records the number of nodes stored by the provenance owner. We show that the mechanism can detect the integrity problem in the provenance graph, namely unauthorized and malicious “authorized” updates even if all the parties, except the TCS, collude to update the provenance. In this scheme, the TCS only needs a very minimal storage (linear with the number of the provenance owners). To protect the confidentiality and for an efficient access control administration, we propose a method to encrypt the provenance graph that allows access by paths and compartments in the provenance graph. We argue that encryption is important as a mechanism to protect the provenance data stored in an untrusted environment. We analyze the security of the integrity mechanism, and perform experiments to measure the performance of both mechanisms.

This paper describes latest RF Automated Test Equipment (RF ATE) technologies that include device under test (DUT) connections, a calibration method, and an RF test module mainly focusing on low cost of test (COT). Most important respect for low COT is how achieve a number of simultaneous measurements and short test time as well as a plain calibration. We realized these respects by a newly proposed calibration method and a drastically downsized RF test module with multiple resources and high throughput. The calibration method is very convenient for RF ATE. Major contribution for downsizing of the RF test module is RF circuit technology in form of RF functional system in package (RF-SIPs), resulting in very attractive test solutions.

Recently, dynamic power supply voltage techniques, such as an Envelope Elimination and Restoration power amplifier (EER-PA) or Envelope-Tracking Power amplifier (ET-PA), have been attracting much attention because they can maintain high efficiency in large back-off region [1]-[6]. The dynamic power supply voltage techniques cause strong nonlinearity compared to a conventional power amplifier, hence a memoryless Digital Predistortion (DPD) technique is indispensable for these efficiency enhancement techniques. However, the performance of the memoryless DPD is degraded due to the frequency response of the envelope amplifier in the dynamic power supply voltage techniques [7]-[9]. In this paper, we clarify the degradation mechanisms of the memoryless DPD for the EER-PA due to the frequency response of the envelope amplifier based on the results of two-tone tests, and propose an analytical model for improving the performance of the memoryless DPD developed for the EER-PA. In addition, a prototype EER-PA is developed and we demonstrate that the residual distortion of the developed EER-PA with conventional memoryless DPD algorithm is compensated by the new algorithm based on the proposed analytical model. In the two-tone test, third-order intermodulation distortion (IMD3) with a tone spacing from 100 kHz to 4 MHz is improvement by up to 25 dB by the memoryless DPD algorithm based on the proposed model. Measured adjacent channel leakage power ratio (ACPR) of the developed EER-PA is improved from -22.5 dBc to -42.5 dBc in the OFDM signal test with 1.08 MHz bandwidth.

In this paper, a new swept-frequency method for the measurement of the complex permittivity and permeability of materials is proposed. The method is based on the S-parameters measurement of a cylindrical material placed inside a rectangular waveguide, where the axis of the cylinder is perpendicular to the narrow waveguide walls. The usage of cylinders in measurement is beneficial because they are easy to fabricate and handle. A novel exact solution of the field scattered by the cylinder is developed. The solution is based on expanding the field in a sum of orthogonal modes in cylindrical coordinates. Excitation coefficients relating the cylindrical scattered field to the waveguide modes are derived, and are used to rigorously formulates the S-parameters. Measurement are performed in the S-band with two dielectric materials (PTFE, nylon), and in the X-band with one magnetic material (ferrite epoxy). The measurement results agree with those from the literature.

In this paper, a simple and efficient design scheme for digital compensation of path imbalances in linear amplification with nonlinear component (LINC) transmitters is proposed to reduce signal distortion. For the LINC transmitters including path imbalances, an error vector magnitude (EVM) is analyzed and an optimal complex gain that minimizes the EVM is extracted. In addition, a straight-forward compensation scheme for the path imbalances is proposed using a least square method for complex gains of each radio frequency path. The effectiveness of the proposed method is compared with the other digital compensation methods. A LINC transmitter with multi-level quadrature amplitude modulation input signals is experimented to verify the performance of the suggested scheme. The proposed compensator can reduce the EVM and the adjacent channel power ratio of the output signals less than 2% and 45 dBc, respectively.

In this paper, we present a supervised learning method to seek out answers to the most frequently asked descriptive questions: reason, method, and definition questions. Most of the previous systems for question answering focus on factoids, lists or definitional questions. However, descriptive questions such as reason questions and method questions are also frequently asked by users. We propose a system for these types of questions. The system conducts an answer search as follows. First, we analyze the user's question and extract search keywords and the expected answer type. Second, information retrieval results are obtained from an existing search engine such as Yahoo or Google . Finally, we rank the results to find snippets containing answers to the questions based on a ranking SVM algorithm. We also propose features to identify snippets containing answers for descriptive questions. The features are adaptable and thus are not dependent on answer type. Experimental results show that the proposed method and features are clearly effective for the task.

We propose and demonstrate a simple and novel technique to accelerate the carrier injection/depletion processes in an RSOA by applying instantaneous injection/depletion currents at the transition edges of the modulation signal to force the carrier density to respond at a high speed and, as a result, to increase its modulation speed. We theoretically and experimentally show that, by using the proposed technique, it is possible to obtain 5 Gbit/s optical BPSK signal from an RSOA having a modulation bandwidth of only 0.9 GHz.

In NGN standards, End Host, also referred to as Terminal Equipment (TE), holds an important place in end-to-end path performance. However, most researchers neglect TE performance when considering performance of end-to-end paths. As far as the authors' knowledge goes, no previous study has proposed a model for TE performance. This paper proposes a method for measuring performance of TE and model extraction based on measurement data. The measurement was made possible with the use of a special NPU (Network Processing Unit) implemented as a programmable NIC. Along with the probing itself, a framework for removing the skew between the NPU and OS is developed in this paper. The multidimensional analysis includes method of probing, packet size and background traffic volume, and studies their effect on TE performance. A method for extracting a generic TE model is proposed. The outcome of this research can be used for modelling TE in simulations and in modelling end-to-end performance when considering QoS in NGN.

More and more mobile devices adopt multi-battery and dynamic voltage scaling policy (DVS) to reduce the energy consumption and extend the battery runtime. However, since the nonlinear characteristics of the multi-battery are not considered, the practical efficiency is not good enough. In order to reduce the energy consumption and extend the battery runtime, this paper proposes an approach based on the battery characteristics to implement the co-optimization of the multi-battery scheduling and dynamic voltage scaling on multi-battery powered systems. In this work, considering the nonlinear discharging characteristics of the existing batteries, we use the Markov process to depict the multi-battery discharging behavior, and build a multi-objective optimal model to denote the energy consumption and battery states, then propose a binary tree based algorithm to solve this model. By means of this method, we get an optimal and applicable scheme about multi-battery scheduling and dynamic voltage scaling. Experimental results show that this approach achieves an average improvement in battery runtime of 17.5% over the current methods in physical implementation.

In OFDMA-based digital duplexing (DD) systems, the effective channel impulse response (CIR) is lengthened due to time difference of arrivals (TDoAs) from adjacent subscriber stations (SSs). In this letter, a time-domain shortening filter (TSF) is proposed to shorten the effective CIR by maximizing signal-to-interference ratio for pulse shortening (SIRPS). A time-domain window (TW) is also proposed to reduce the effect of inter-carrier interference (ICI) due to CFO in OFDMA-based DD systems, by maximizing the signal-to-interference and noise ratio for window (SINRW).

This paper presents a novel inpainting method based on structure estimation. The method first estimates an initial image that captures the rough structure and colors in the missing region. This image is generated by probabilistically estimating the gradient within the missing region based on edge segments intersecting its boundary, and then by flooding the colors on the boundary into the missing region. The color flooding is formulated as an energy minimization problem, and is efficiently optimized by the conjugate gradient method. Finally, by locally replacing the missing region with local patches similar to both the adjacent patches and the initial image, the inpainted image is synthesized. The initial image not only serves as a guide to ensure the underlying structure is preserved, but also allows the patch selection process to be carried out in a greedy manner, which leads to substantial speedup. Experimental results show the proposed method is capable of preserving the underlying structure in the missing region, while achieving more than 5 times faster computational speed than the state-of-the-art inpainting method. Subjective evaluation of image quality also shows the proposed method outperforms the previous methods.

A highly stable microwave exciter system has been developed for 87Sr+ ion microwave frequency standards. The controller was built to optimize the transfer function of the phase-locked loop. The upper limit of the frequency tracking error achieved was 7.7 10-15 at τ = 1 s. A phase frequency discriminator using an FPGA was also made and applied to a phase-locked loop. This paper reports on the design of and results obtained from the microwave exciter for Sr+ ion microwave frequency standards.

A novel delta-sigma modulator that employs a non-uniform quantizer whose spacing is adjusted by reference to the statistical properties of the input signal is proposed. The proposed delta-sigma modulator has less quantization noise compared to the one that uses a uniform quantizer with the same number of output values. With respect to the quantizer on its own, Lloyd proposed a non-uniform quantizer that is best for minimizing the average quantization noise power. The applicable condition of the method is that the statistical properties of the input signal, the probability density, are given. However, the procedure cannot be directly applied to the quantizer in the delta-sigma modulator because it jeopardizes the modulator's stability. In this paper, a procedure is proposed that determine the spacing of the quantizer with avoiding instability. Simulation results show that the proposed method reduces quantization noise by up to 3.8 dB and 2.8 dB with the input signal having a PAPR of 16 dB and 12 dB, respectively, compared to the one employing a uniform quantizer. Two alternative types of probability density function (PDF) are used in the proposed method for the calculation of the output values. One is the PDF of the input signal to the delta-sigma modulator and the other is an approximated PDF of the input signal to the quantizer inside the delta-sigma modulator. Both approaches are evaluated to find that the latter gives lower quantization noise.

In this letter, a novel steganographic method with four-pixel differencing and exploiting modification direction is proposed. Secret data are embedded into each four-pixel block by adaptively applying exploiting modification direction technique. The difference value of the four-pixel block is used to judge whether the pixels in edge areas can tolerate larger changes than those in smooth areas. The readjustment guarantees to extract the secret data exactly and to minimize the embedding distortion. Since the proposed method processes non-overlapping 22 pixels blocks instead of two consecutive pixels, the features of edge can be considered sufficiently. Compared with the previous method, experimental results show that the proposed method provides better performance, i.e., larger embedding capacity and better image quality.

Raster maps are widely available in the everyday life, and can contain a huge amount of information of any kind using labels, pictograms, or color code e.g. However, it is not an easy task to extract roads from those maps due to those overlapping features. In this paper, we focus on an automated method to extract roads by using linear features detection to search for seed points having a high probability to belong to roads. Those linear features are lines of pixels of homogenous color in each direction around each pixel. After that, the seeds are then expanded before choosing to keep or to discard the extracted element. Because this method is not mainly based on color segmentation, it is also suitable for handwritten maps for example. The experimental results demonstrate that in most cases our method gives results similar to usual methods without needing any previous data or user input, but do need some knowledge on the target maps; and does work with handwritten maps if drawn following some basic rules whereas usual methods fail.

The authors propose a new method of controlling the isolation of an RF splitter. In the proposed method, a bias current is superimposed on an RF signal to change the permeability of the ferrite core used in the splitter's transformer. By doing this, the splitter isolation can be controlled. Experimental results have shown that superimposing a bias current of 500 mA improves device isolation by about 5 dB without affecting the loss characteristics.

In a large software system development project, many documents are prepared and updated frequently. In such a situation, support is needed for looking through these documents easily to identify inconsistencies and to maintain traceability. In this research, we focus on the requirements documents such as use cases and consider how to create models from the use case descriptions in unformatted text. In the model construction, we propose a few semantic constraints based on the features of the use cases and use them for a predicate argument structure analysis to assign semantic labels to actors and actions. With this approach, we show that we can assign semantic labels without enhancing any existing general lexical resources such as case frame dictionaries and design a less language-dependent model construction architecture. By using the constructed model, we consider a system for quality analysis of the use cases and automated test case generation to keep the traceability between document sets. We evaluated the reuse of the existing use cases and generated test case steps automatically with the proposed prototype system from real-world use cases in the development of a system using a packaged application. Based on the evaluation, we show how to construct models with high precision from English and Japanese use case data. Also, we could generate good test cases for about 90% of the real use cases through the manual improvement of the descriptions based on the feedback from the quality analysis system.