In the classical computation theory, the language of a system features the computational behavior of the system but it does not distinguish the determinism and nondeterminism of actions. However, Milner found that the determinism and nondeterminism affect the interactional behavior of interactive systems and thus the notion of language does not features the interactional behavior. Therefore, Milner proposed the notion of (weak) bisimulation to solve this problem. With the development of internet, more and more interactive systems occur in the world, such as electronic trading system. Security is one of the most important topics for these systems. We find that different security policies can also affect the interactional behavior of a system, which exactly is the reason why a good policy can strengthen the security. In other words, two interactive systems with different security policies are not of an equivalent behavior although their functions (or business processes) are identical. However, the classic (weak) bisimulation theory draws an opposite conclusion that their behaviors are equivalent. The notion of (weak) bisimulation is not suitable for these security-oriented interactive systems since it does not consider a security policy. This paper proposes the concept of secure bisimulation in order to solve the above problem.

We propose a highly sensitive carrier-recovery system for in-line amplification for binary phase shift keying (BPSK) signals in a periodically poled LiNbO3 based phase sensitive amplifier (PSA). We applied a discrete two-stage second harmonic generation/difference frequency generation (SHG/DFG) parametric conversion scheme to enhance the sensitivity of the carrier recovery. Owing to this two-stage SHG/DFG scheme, the conversion efficiency of the seed light for the injection locking needed for the pump generation can be improved compared to that of the cascaded SHG/DFG scheme. The new discrete scheme might also prevent the SNR degradation of the seed light caused by the ASE from the booster EDFA compared with the previous system that used the cascaded scheme. This novel carrier-recovery system exhibits high sensitivity with the SNR of over 7.8dB of the seed light, while tapped signal power is as low as -50dBm, which is low enough for injection locking. The new in-line PSA with this carrier-recovery system exhibits high gain of over 11dB. Since we successfully obtained the high gain property, we tried multistage amplification taking into account practical use and achieved it with both a high gain of 20dB and a noise figure that is almost as low as the standard quantum limit of a PSA.

An asymmetric left-handed coupled-line is presented to implement the tight forward coupler. Two left-handed transmission lines are coupled through its shunt inductors. The numerical procedures based on the generalized four-port scattering parameters combined with the periodical boundary conditions are applied to extract the modal characteristics of the asymmetric coupled-line, and theoretically predict that the proposed coupled-line can make a normalized phase constant of c mode 1.57 times larger than π mode for the forward coupler miniaturization. The design curves based on different overlapping length of the shunt inductors are reported for the coupler design. The procedures, so-called the port-reduction-method (PRM), are applied to experimentally characterize the coupler prototype using the two-port instruments. The measured results confirm that prototype uses 0.21 λg at 430 GHz to achieve -4.55 dB forward coupling with 13% 1-dB operating bandwidth.

A striped inductor and its utilization of a voltage-controlled oscillator (VCO) are studied with the aim of suppressing phase noise degradation in K- and Ka-bands. The proposed striped inductor exhibits reduced series resistance in the high frequency region by increasing the cross-sectional peripheral length, as with the Litz wire, and the VCO of the striped inductor simultaneously exhibits a lower phase noise than that of the conventional inductor. Striped and conventional inductors and VCOs are designed and fabricated, and their use of K- and Ka-bands is measured. Results show that the Q factor and corner frequency of the striped inductor are approximately 1.3 and 1.6 times higher, respectively, than that of the conventional inductor. Moreover, the 1-MHz-offset phase noise of the striped inductor's VCO in the K- and Ka-bands was approximately 3.5 dB lower than that of the conventional inductor. In this study, a 65-nm standard CMOS process was used.

A generalized covariance matrix taper (GCMT) model is proposed to enhance the performance of knowledge-aided space-time adaptive processing (KA-STAP) under sea clutter environments. In KA-STAP, improving the accuracy degree of the a priori clutter covariance matrix is a fundamental issue. As a crucial component in the a priori clutter covariance matrix, the taper matrix is employed to describe the internal clutter motion (ICM) or other subspace leakage effects, and commonly constructed by the classical covariance matrix taper (CMT) model. This work extents the CMT model into a generalized CMT (GCMT) model with a greater degree of freedom. Comparing it with the CMT model, the proposed GCMT model is more suitable for sea clutter background applications for its improved flexibility. Simulation results illustrate the efficiency of the GCMT model under different sea clutter environments.

A low-voltage controller-based all-digital phase-locked loop (ADPLL) utilized in the medical implant communication service (MICS) frequency band was designed in this study. In the proposed design, controller-based loop topology is used to control the phase and frequency to ensure the reliable handling of the ADPLL output signal. A digitally-controlled oscillator with a delta-sigma modulator was employed to achieve high frequency resolution. The phase error was reduced by a phase selector with a 64-phase signal from the phase interpolator. Fabricated using a 130-nm CMOS process, the ADPLL has an active area of 0.64 mm2, consumes 840 µW from a 0.7-V supply voltage, and has a settling time of 80 µs. The phase noise was measured to be -114 dBc/Hz at an offset frequency of 200 kHz.

This paper presents a varactor-based all-digital phase-locked loop (ADPLL) with a multi-phase digitally controlled oscillator (DCO) for near-threshold voltage operation. In addition, a new all-digital reference spur suppression (RSS) circuit with multiple phases random-sampling techniques to effectively spread the reference clock frequency is proposed to randomize the synchronized DCO register behavior and reduce the reference spur. Because the equivalent reference clock frequency is reserved, the loop behavior is maintained. The area of the proposed spur suppression circuit is only 4.9% of the ADPLL (0.038 mm2). To work reliably at the near-threshold region, a multi-phase DCO with NMOS varactors is presented to acquire precise frequency resolution and high linearity. In the near-threshold region (VDD =0.52 V), the ADPLL only dissipates 269.9 μW at 100 MHz output frequency. It has a reference spur of -52.2 dBc at 100 MHz output clock frequency when the spur suppression circuit is deactivated. When the spur suppression circuit is activated, the ADPLL shows a reference spur of -57.3 dBc with the period jitter of 0.217% UI.

In RFID-enabled supply chains, it is necessary to protect the contents of EPCs (Electronic Product Code) since an EPC contains sensitive information such as the product code and serial number and could be used for counterfeits. Although many protection schemes have been proposed, no scheme can limit the number of illegal attempts for discovering EPCs or notice whether an attacker exists. In this paper, we propose an illegal interrogation detectable products distribution scheme for RFID-enabled supply chains. The idea is to detect the attacker by forcing him/her to access an authentication server. Our scheme masks EPCs with random sequences. Masked EPCs are written into genuine tags on products while random sequences are placed on an authentication server with an access code. An access code is divided into shares with a secret sharing scheme and they are written into genuine tags. We also write bogus shares into extra off-the-shelf tags that are not attached to any products. Since an attacker who wants to know genuine EPCs may obtain a large number of access code candidates and must try each on the authentication server, the server can detect the attacker.

Web Service Composition (WSC) has been well recognized as a convenient and flexible way of service sharing and integration in service-oriented application fields. WSC aims at selecting and composing a set of initial services with respect to the Quality of Service (QoS) values of their attributes (e.g., price), in order to complete a complex task and meet user requirements. A major research challenge of the QoS-aware WSC problem is to select a proper set of services to maximize the QoS of the composite service meeting several QoS constraints upon various attributes, e.g. total price or runtime. In this article, a fast algorithm based on QoS-aware sampling (FAQS) is proposed, which can efficiently find the near-optimal composition result from sampled services. FAQS consists of five steps as follows. 1) QoS normalization is performed to unify different metrics for QoS attributes. 2) The normalized services are sampled and categorized by guaranteeing similar number of services in each class. 3) The frequencies of the sampled services are calculated to guarantee the composed services are the most frequent ones. This process ensures that the sampled services cover as many as possible initial services. 4) The sampled services are composed by solving a linear programming problem. 5) The initial composition results are further optimized by solving a modified multi-choice multi-dimensional knapsack problem (MMKP). Experimental results indicate that FAQS is much faster than existing algorithms and could obtain stable near-optimal result.

In this paper, we propose a method to estimate the most resource-consuming disease from electronic claim data based on Labeled Latent Dirichlet Allocation (Labeled LDA). The proposed method models each electronic claim from its medical procedures as a mixture of resource-consuming diseases. Thus, the most resource-consuming disease can be automatically estimated by applying Labeled LDA to the electronic claim data. Although our method is composed of a simple scheme, this is the first trial for realizing estimation of the most resource-consuming disease.

This study proposes a novel resonator design that uses tightly coupled parallel coils to improve the quality factor (Q factor) in coupled magnetic resonance wireless power transfer. Depending on the characteristics of the tightly coupled parallel-connected coils, the proposed resonator can offer significantly reduced resistance with very little self-inductance loss. A double-layer spiral coil structure is used for resonator design and evaluating its characteristics. Measured results show that a resonator consisting of two identical, tightly coupled parallel double-layer spiral coils can match the Q factor of a conventional double-layer spiral coil with the same number of turns, even though its equivalent resistance is approximately 75% less. Moreover, the system power transfer performance of the resonator was measured under the impedance matching condition. To further reduce the resistance, we propose another resonator comprising of three parallel and tightly coupled double-layer spiral coils, and measure its equivalent resistance characteristics for different wire gap sizes.

We developed an electrically driven near-infrared broadband light source based on self-assembled InAs quantum dots (QDs). By combining emissions from four InAs QD ensembles with controlled emission center wavelengths, electro-luminescence (EL) with a Gaussian-like spectral shape and approximately 85-nm bandwidth was obtained. The peak wavelength of the EL was blue-shifted from approximately 1230 to 1200 nm with increased injection current density (J). This was due to the state-filling effect: sequential filling of the discrete QD electron/hole states by supplied carriers from lower (ground state; GS) to higher (excited state; ES) energy states. The EL intensities of the ES and GS emissions exhibited different J dependence, also because of the state-filling effect. The point-spread function (PSF) deduced from the Fourier-transformed EL spectrum exhibited a peak without apparent side lobes. The half width at half maximum of the PSF was 6.5 µm, which corresponds to the estimated axial resolution of the optical coherence tomography (OCT) image obtained with this light source. These results demonstrate the effectiveness of the QD-based device for realizing noise-reduced high-resolution OCT.

On-chip neural interface devices based on CMOS image sensor technology are proposed and demonstrated. The devices were designed with target applications to optogenetics in bioscience. Multifunctional CMOS image sensors equipped with an addressable on-chip electrode array were integrated with a functional interface chip that contained embedded GaInN light emitting diodes (LEDs) and electrodes to create a neural interface. Detailed design information regarding the CMOS sensor chip and the functional interface chip including the packaging structure and fabrication processes are presented in this paper. The on-chip optical stimulation functionality was demonstrated in an in vitro experiment using neuron-like cells cultured on the proposed device.

In this letter, the problem of how to set reserve prices so as to improve the primary user's revenue in the second price-sealed auction under the incomplete information of secondary users' private value functions is investigated. Dirichlet process is used to predict the next highest bid based on historical data of the highest bids. Before the beginning of the next auction round, the primary user can obtain a reserve price by maximizing the additional expected reward. Simulation results show that the proposed scheme can achieve an improvement of the primary user's averaged revenue compared with several counterparts.

A novel directional coupler loaded with feedback capacitances on the coupled lines is presented. Its effect of enhancing the coupling is qualitatively shown by deriving an equation for the coupling. Besides, a method to compensate for the phase difference between the even and odd modes of the coupler is presented. To demonstrate, a novel tandem 3-dB coupler consisting of the proposed coupled lines is designed and described. In addition, a waveguide (rectangular coaxial line) 8×8 HYB matrix using planar double-layer structure that is composed of the proposed tandem 3-dB couplers and branch-line couplers, which is operated in S-band, is designed and fabricated showing excellent performance.

In recent years, various Portable Navigation Devices (PND) such as smart-phones are becoming popular as a vehicle navigation device. To compare with a conventional built-in navigation system, PND has advantages that it is low cost and easily mounted to the vehicle. On the other hand, PND has also disadvantage that in the most case it cannot obtain the reliable vehicle speed information such as wheel pulse information and that induces degradation of vehicle trajectory estimation (dead-reckoning). The vehicle trajectory estimation is the positioning method using inertial sensors, and generally used when GPS is not available. So in urban area where GPS signals are blocked or reflected by tall buildings, the degradation of vehicle trajectory estimation may cause the severe increase of position error. Accordingly, in this study two approaches are proposed to improve vehicle trajectory estimation with PND. The first one is the accurate speed estimation using time-series tightly coupled integration of accelerometer, gyro, and Doppler shift of GPS. And the second one is the correction of trajectory error using backward refinement that can work even in real-time processing. The experimental result in Shinjuku which is dense urban city shows that the error of vehicle trajectory estimation was reduced to 1/4 compared with the previous method.

Personal e-healthcare service is growing significantly. A large number of personal e-health measuring and monitoring devices are now in the market. However, to achieve better health outcome, various devices or services need to work together. This coordination among services remains challenge, due to their variations and complexities. To address this issue, we have proposed an ontology-based framework for interactive self-assessment of RESTful e-health services. Unlike existing e-health service frameworks where they had tightly coupling between services, as well as their data schemas were difficult to change and extend in the future. In our work, the loosely coupling among services and flexibility of each service are achieved through the design and implementation based on HYDRA vocabulary and REST principles. We have implemented clinical knowledge through the combination of OWL-DL and SPARQL rules. All of these services evolve independently; their interfaces are based on REST principles, especially HATEOAS constraints. We have demonstrated how to apply our framework for interactive self-assessment in e-health applications. We have shown that it allows the medical knowledge to drive the system workflow according to the event-driven principles. New data schema can be maintained during run-time. This is the essential feature to support arriving of IoT (Internet of Things) based medical devices, which have their own data schema and evolve overtime.

The objective of this paper is to recognize and classify the poses of idols in still images on the web. The poses found in Japanese idol photos are often complicated and their classification is highly challenging. Although advances in computer vision research have made huge contributions to image recognition, it is not enough to estimate human poses accurately. We thus propose a method that refines result of human pose estimation by Pose Guide Ontology (PGO) and a set of energy functions. PGO, which we introduce in this paper, contains useful background knowledge, such as semantic hierarchies and constraints related to the positional relationship between body parts. Energy functions compute the right positions of body parts based on knowledge of the human body. Through experiments, we also refine PGO iteratively for further improvement of classification accuracy. We demonstrate pose classification into 8 classes on a dataset containing 400 idol images on the web. Result of experiments shows the efficiency of PGO and the energy functions; the F-measure of classification is 15% higher than the non-refined results. In addition to this, we confirm the validity of the energy functions.

Up to now, broadband THz time-domain system has been developed and widely used for THz inspection system; however for many THz devices for THz band wireless communication, narrow-band system would be preferred rather than typical broadband system. In this work we established a narrowband and time-domain THz radiation and detection system and characterized uncooled microbolometer-based THz imagers using that system. The central frequency of generated narrowband THz wave was 850 GHz. This system enables simultaneous measurement of pulse energy and waveform of THz pulse using a superconducting transition edge sensor for measuring energy and electro-optic sampling for measuring THz waveform. We used this system to evaluate the performance of uncooled THz imagers; IRV-T0831 and T0832 from NEC. Noise equivalent power (NEP) of approximately 0.22 pW/Hz1/2 was achieved in case of T0832 at less than 1 THz which is lower than NEP value of previous reports.

The primitive called public key encryption with non-interactive opening (PKENO) is a class of public key encryption (PKE) with additional functionality. By using this, a receiver of a ciphertext can prove that the ciphertext is an encryption of a specified message in a publicly verifiable manner. In some situation that a receiver needs to claim that a ciphertext is NOT decrypted to a specified message, if he/she proves the fact by using PKENO straightforwardly, the real message of the ciphertext is revealed and a verifier checks that it is different from the specified message about which the receiver wants to prove. However, this naive solution is problematic in terms of privacy. Inspired by this problem, we propose the notion of disavowable public key encryption with non-interactive opening (disavowable PKENO) where, with respect to a ciphertext and a message, the receiver of the ciphertext can issue a proof that the plaintext of the ciphertext is NOT the message. Also, we give a concrete construction. Specifically, a disavowal proof in our scheme consists of 61 group elements. The proposed disavowable PKENO scheme is provably secure in the standard model under the decisional linear assumption and strong unforgeability of the underlying one-time signature scheme.