In this paper, a differential input/output linear MOS transconductor using an adaptively biasing technique is proposed. The proposed transconductor based on a differential pair is linearized by employing an adaptively biasing circuit. The linear characteristic of the individual differential output currents are obtained by introducing the adaptively biased currents to terminate the differential output terminals. Using the proposed technique, the common-mode rejection ration (CMRR) becomes high. Simulation results show that the proposed technique is effective for improvement of the linearity and other performances.

Energy conservation is an important issue in mobile ad hoc networks (MANET), where the terminals are always supplied with limited energy. A new routing protocol is presented according to the study on the influence of low-energy nodes in ad hoc networks. The novel routing protocol (energy sensing routing protocol, ESRP) is based on the energy sensing strategy. Multiple strategy routing and substitute routing are both adopted in this paper. Referring to the level of the residual energy and the situation of energy consumption, different routes are chosen for packets transmission. The local maintenance is adopted, which can reduce packets retransmission effectively when the link breaks. We focus on the network lifetime most in all performances. The evaluation is done in comparison with other routing protocols on NS2 platform, and the simulation results show that this routing protocol can prolong the network lifetime and balance energy consumption effectively.

There are a great amount of various resources described in many different ways for service oriented grid environment, while traditional grid resource discovery methods could not fit more complex future grid system. Therefore, this paper proposes a novel grid resource discovery method based on association rule hypergraph partitioning algorithm which analyzes user behavior in history transaction records to provide personality service for user. And this resource discovery method gives a new way to improve resource retrieval and management in grid research.

The separation and localization of sound source signals are important techniques for many applications, such as highly realistic communication and speech recognition systems. These systems are expected to work without such prior information as the number of sound sources and the environmental conditions. In this paper, we developed a dodecahedral microphone array and proposed a novel separation method with our developed device. This method refers to human sound localization cues and uses acoustical characteristics obtained by the shape of the dodecahedral microphone array. Moreover, this method includes an estimation method of the number of sound sources that can operate without prior information. The sound source separation performances were evaluated under simulated and actual reverberant conditions, and the results were compared with the conventional method. The experimental results showed that our separation performance outperformed the conventional method.

We propose a design optimization flow for a high-speed and low-power operational transconductance amplifier (OTA) using a gm/ID lookup table design methodology in scaled CMOS. This methodology advantages from using gm/ID as a primary design parameter to consider all operation regions including strong, moderate, and weak inversion regions, and enables the lowest power design. SPICE-based lookup table approach is employed to optimize the operation region specified by the gm/ID with sufficient accuracy for short-channel transistors. The optimized design flow features 1) a proposal of the worst-case design scenario for specification and gm/ID lookup table generations from worst-case SPICE simulations, 2) an optimization procedure accomplished by the combination of analytical and simulation-based approaches in order to eliminate tweaking of circuit parameters, and 3) an additional use of gm/ID subplots to take second-order effects into account. A gain-boosted folded-cascode OTA for a switched capacitor circuit is adopted as a target topology to explore the effectiveness of the proposed design methodology for a circuit with complex topology. Analytical expressions of the gain-boosted folded-cascode OTA in terms of DC gain, frequency response and output noise are presented, and detailed optimization of gm/IDs as well as circuit parameters are illustrated. The optimization flow is verified for the application to a residue amplifier in a 10-bit 125 MS/s pipeline A/D converter implemented in a 0.18 µm CMOS technology. The optimized circuit satisfies the required specification for all corner simulations without additional tweaking of circuit parameters. We finally explore the possibility of applying this design methodology as a technology migration tool, and illustrate the failure analysis by comparing the differences in the gm/ID characteristics.

With the aim to improve the effectiveness of SAWSDL service discovery, this paper proposes a novel discovery method for SAWSDL services, which is based on the matchmaking of so-called fine-grained data semantics that is defined via sets of atomic elements with built-in data types. The fine-grained data semantics can be obtained by a transformation algorithm that decomposes parameters at message level into a set of atomic elements, considering the characteristics of SAWSDL service structure and semantic annotations. Then, a matchmaking algorithm is proposed for the matching of fine-grained data semantics, which avoids the complex and expensive structural matching at the message level. The fine-grained data semantics is transparent to the specific data structure of message-level parameters, therefore, it can help to match successfully similar Web services with different data structures of parameters. Moreover, a comprehensive measure is proposed by considering together several important components of SAWSDL service descriptions at the same time. Finally, this method is evaluated on SAWSDL service discovery test collection SAWSDL-TC2 and compared with other SAWSDL matchmakers. The experimental results show that our method can improve the effectiveness of SAWSDL service discovery with low average query response time. The results imply that fine-grained parameters fit to represent the data semantics of SAWSDL services, especially when data structures of parameters are not important for semantics.

Recently, to track and relate news documents from several sources, association rule mining has been applied due to its performance and scalability. This paper presents an empirical investigation on how term representation basis, term weighting, and association measure affects the quality of relations discovered among news documents. Twenty four combinations initiated by two term representation bases, four term weightings, and three association measures are explored with their results compared to human judgment of three-level relations: completely related, somehow related, and unrelated relations. The performance evaluation is conducted by comparing the top-k results of each combination to those of the others using so-called rank-order mismatch (ROM). The experimental results indicate that a combination of bigram (BG), term frequency with inverse document frequency (TFIDF) and confidence (CONF), as well as a combination of BG, TFIDF and conviction (CONV), achieves the best performance to find the related documents by placing them in upper ranks with 0.41% ROM on top-50 mined relations. However, a combination of unigram (UG), TFIDF and lift (LIFT) performs the best by locating irrelevant relations in lower ranks (top-1100) with 9.63% ROM. A detailed analysis on the number of the three-level relations with regard to their rankings is also performed in order to examine the characteristic of the resultant relations. Finally, a discussion and an error analysis are given.

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 study focuses on speaker adaptation techniques for Computer-Assisted Language Learning (CALL). We first investigate the effects and problems of Maximum Likelihood Linear Regression (MLLR) speaker adaptation when used in pronunciation evaluation. Automatic scoring and error detection experiments are conducted on two publicly available databases of Japanese learners' English pronunciation. As we expected, over-adaptation causes misjudgment of pronunciation accuracy. Following the analysis, we propose a novel method, Regularized Maximum Likelihood Regression (Regularized-MLLR) adaptation, to solve the problem of the adverse effects of MLLR adaptation. This method uses a group of teachers' data to regularize learners' transformation matrices so that erroneous pronunciations will not be erroneously transformed as correct ones. We implement this idea in two ways: one is using the average of the teachers' transformation matrices as a constraint to MLLR, and the other is using linear combinations of the teachers' matrices to represent learners' transformations. Experimental results show that the proposed methods can better utilize MLLR adaptation and avoid over-adaptation.

This letter proposes a simple k-hop flooding scheme for the temporarily lost child node of a multicast tree in a mobile ad hoc network where a group of nodes move together within a bound. Through simulation, we show that our scheme improves the packet delivery ratio of MAODV to be comparable to the epidemic routing with only small additional duplicate packets.

This paper presents Q factor analysis for FET oscillators employing distributed-constant elements. We replace the inductor of a lumped constant Colpitts circuit by a shorted microstrip transmission line for high frequency applications. Involving the FET's transconductance and the transmission line's loss due to both conducting metal and dielectric substrate, we deduce the Q factor formula for the entire circuit in the steady oscillation state. We compared the computed results from the oscillator employing an uniform shorted microstrip line with that of the original LC oscillator. For obtaining even higher Q factor, we modify the shape of transmission line into nonuniform, i.e., step-, tapered-, and partially-tapered stubs. Non-uniformity causes some complexity in the impedance analysis. We exploit a piecewise uniform approximation for tapered part of the microstrip stub, and then involve the asymptotic expressions obtained from both stub's impedance and its frequency derivatives into the active Q factor formula. Applying these formulations, we calculate out the value of capacitance for tuning, the necessary FET's transconductance and achievable active Q factor, and then finally explore oscillator performances with a microstrip stub in different shapes and sizes.

This paper discusses speaker verification (SV) using Gaussian mixture models (GMMs), where only utterances of enrolled speakers are required. Such an SV system can be realized using artificially generated cohorts instead of real cohorts from speaker databases. This paper presents a rational approach to set GMM parameters for artificial cohorts based on statistics of GMM parameters for real cohorts. Equal error rates for the proposed method are about 10% less than those for the previous method, where GMM parameters for artificial cohorts were set in an ad hoc manner.

High integration and low power operation of integrated circuits make noise sensitivity high. Therefore, it is important to reduce noise of circuits. A bias-offset transconductor is known as a linear transconductor. It is expected that noise sensitivity of the transconductor becomes higher due to improvement of linearity and reduction of power dissipation. This paper proposes a design method to reduce noise considering high linearity, reduction of power dissipation and small circuit size.

Binary maximal-length sequences (or m-sequences) are sequences of period 2m-1 generated by a linear recursion of degree m. Decimating an m-sequence {st} by an integer d relatively prime to 2m-1 leads to another m-sequence {sdt} of the same period. The crosscorrelation of m-sequences has many applications in communication systems and has been an important and well studied problem during more than 40 years. This paper presents an updated survey on the crosscorrelation between binary m-sequences with at most five-valued crosscorrelation and shows some of the many recent connections of this problem to several areas of mathematics such as exponential sums and Dickson polynomials.

The proposed automated scoring system for English writing tests provides an assessment result including a score and diagnostic feedback to test-takers without human's efforts. The system analyzes an input sentence and detects errors related to spelling, syntax and content similarity. The scoring model has adopted one of the statistical approaches, a regression tree. A scoring model in general calculates a score based on the count and the types of automatically detected errors. Accordingly, a system with higher accuracy in detecting errors raises the accuracy in scoring a test. The accuracy of the system, however, cannot be fully guaranteed for several reasons, such as parsing failure, incompleteness of knowledge bases, and ambiguous nature of natural language. In this paper, we introduce an error-weighting technique, which is similar to term-weighting widely used in information retrieval. The error-weighting technique is applied to judge reliability of the errors detected by the system. The score calculated with the technique is proven to be more accurate than the score without it.

A CMOS transconductor for multi-mode application is presented. The transconductor includes a voltage-to-current converter and a current multiplier. Voltage-to-current conversion employs linear region MOS transistors, and the conversion features high linearity over a wide input swing range. The current multiplier, which operates in the weak inversion region, provides a wide transconductance tuning range without degrading the linearity. The transconductor was designed and fabricated in the TSMC 0.18-µm CMOS process. The results show the transconductance tuning ratio of 23 and the IM3 performance of -68.5 dB.

In this paper, we present a new composite transistor circuit design technique that provides superior performance enhancement to analog circuits. By adding a composite transistor to the cascode-compensated amplifier, it has achieved a 102 dB DC gain, and a 37.6 MHz unity gain bandwidth while driving a 2 nF heavy capacitive load at a single 1.8 V supply. In the comparison of power-bandwidth and power-speed efficiencies on figures of merit, it offers significantly high values with respect to the reported state-of-the-art works. By employing the composite transistor in a linear regulator powered by a 3.3 V supply to generate a 1.8 V output voltage, it has shown fast recovery response at various load current transients, having a 1% settling time of 0.1 µS for a 50 mA or 100 mA step, while a 1% settling time of 0.36 µS for a maximum 735 mA step under a capacitive load of 10 µF with a 1 Ω ESR resistor. The simulated load regulation is 0.035% and line regulation is 0.488%. Comparing its results with other state-of-art LDO reported results, it also validates the significant enhanced performance of the proposed composite-transistor-based design in terms of speed, current driving capability and stability against changes in environmental parameters. All the proposed designs are simulated using chartered semiconductor (CSM) 1.8 V/3.3 V 0.18 µm CMOS triple-well process technology with thin/thick oxide options and BSIM3 model parameters.

Despite their usability advantages over traditional authentication systems, biometrics-based authentication systems suffer from inherent privacy violation and non-revocability issues. In order to address these issues, the concept of cancelable biometrics was introduced as a means of generating multiple, revocable, and noninvertible identities from true biometric templates. Apart from BioHashing, which is a two-factor cancelable biometrics technique based on mixing a set of tokenized user-specific random numbers with biometric features, cancelable biometrics techniques usually cannot preserve the recognition accuracy achieved using the unprotected biometric systems. However, as the employed token can be lost, shared, or stolen, BioHashing suffers from the same issues associated with token-based authentication systems. In this paper, a reliable tokenless cancelable biometrics scheme, referred to as BioEncoding, for protecting IrisCodes is presented. Unlike BioHashing, BioEncoding can be used as a one-factor authentication scheme that relies only on sole IrisCodes. A unique noninvertible compact bit-string, referred to as BioCode, is randomly derived from a true IrisCode. Rather than the true IrisCode, the derived BioCode can be used efficiently to verify the user identity without degrading the recognition accuracy obtained using original IrisCodes. Additionally, BioEncoding satisfies all the requirements of the cancelable biometrics construct. The performance of BioEncoding is compared with the performance of BioHashing in the stolen-token scenario and the experimental results show the superiority of the proposed method over BioHashing-based techniques.

Multi-hop Wireless LAN-based mesh network (WMN) provides high capacity and self-configuring capabilities. Due to data forwarding and path selection based on MAC address, WMN requires additional operations to achieve global connectivity using IPv6 address. The neighbor discovery operation over WLAN mesh networks requires repeated all-node broadcasting and this gives rise to a big burden in the entire mesh networks. In this letter, we propose the proxy neighbor discovery scheme for optimized IPv6 communication over WMN to reduce network overhead and communication latency. Using simulation experiments, we show that the control overhead and communication setup latency can be significantly reduced using the proxy-based neighbor discovery mechanism.

An implantable WBAN path-loss model for a capsule endoscopy which is used for examining digestive organs, is developed by conducting simulations and experiments. First, we performed FDTD simulations on implant WBAN propagation by using a numerical human model. Second, we performed FDTD simulations on a vessel that represents the human body. Third, we performed experiments using a vessel of the same dimensions as that used in the simulations. On the basis of the results of these simulations and experiments, we proposed the gradient and intercept parameters of the simple path-loss in-body propagation model.