An efficient algorithm to reduce the noise from the Nuclear Magnetic Resonance Free Induction Decay (NMR FID) signals is presented, in this paper, via the oversampled real-valued discrete Gabor transform using the Gaussian synthesis window. An NMR FID signal in the Gabor transform domain (i.e., a joint time-frequency domain) is concentrated in a few number of Gabor transform coefficients while the noise is fairly distributed among all the coefficients. Therefore, the NMR FID signal can be significantly enhanced by performing a thresholding technique on the coefficients in the transform domain. Theoretical and simulation experimental analyses in this paper show that the oversampled Gabor transform using the Gaussian synthesis window is more suitable for the NMR FID signal enhancement than the critically-sampled one using the exponential synthesis window, because both the Gaussian synthesis window and its corresponding analysis window in the oversampling case can have better localization in the frequency domain than the exponential synthesis window and its corresponding analysis window in the critically-sampling case. Moreover, to speed up the transform, instead of the commonly-used complex-valued discrete Gabor transform, the real-valued discrete Gabor transform presented in our previous work is adopted in the proposed algorithm.

An alaryngeal speech enhancement system is proposed to improve the intelligibility and quality of speech signals generated by an artificial larynx transducer (ALT). Proposed system identifies the voiced segments of alaryngeal speech signal, by using pattern recognition methods, and replaces these by their equivalent voiced segments of normal speech. Evaluation results show that proposed system provides a fairly good improvement of the quality and intelligibility of ALT generated speech.

In this letter, we consider a problem of global exponential stabilization of a class of approximately feedback linearized systems. With a newly proposed LMI-condition, we propose a controller design method which is shown to be improved over the existing methods in several aspects.

In this paper, we address issues in improving hands-free speech recognition performance in different car environments using multiple spatially distributed microphones. In the previous work, we proposed the multiple linear regression of the log spectra (MRLS) for estimating the log spectra of speech at a close-talking microphone. In this paper, the concept is extended to nonlinear regressions. Regressions in the cepstrum domain are also investigated. An effective algorithm is developed to adapt the regression weights automatically to different noise environments. Compared to the nearest distant microphone and adaptive beamformer (Generalized Sidelobe Canceller), the proposed adaptive nonlinear regression approach shows an advantage in the average relative word error rate (WER) reductions of 58.5% and 10.3%, respectively, for isolated word recognition under 15 real car environments.

About 20-45% of the total power in any VLSI circuit is consumed by the clocking system and 90% of this power consumption is spent by flip-flops. Wider datapaths, deeper pipelines, and increasing number of registers in modern processors have underscored the importance of the flip-flops. As a result, the flip-flops' performance metrics such as, power, delay, and power delay product will become a crucial factor in overall performance of processors. As technology is moving into deep submicron level, noise immunity and noise generated by any component in a digital device is also becoming a vital factor in circuit design. This paper studies various flip-flop designs for their noise immunity and noise generation metrics. It categorizes the flip-flops and reports extensive simulation results for best representative examples including the newly proposed one from the group (a patent is filed for this flip-flop). It compares power, delay, power delay product, number of transistors, number of clocked transistors, noise immunity, and noise generation for flip-flops that are reported as ones with the best performances in the literature.

Nowadays, numerous Medium Access Control (MAC) contention protocols for ad hoc networks typically use a fixed transmit power level without using any transmit power control. In this paper, we present an enhancement scheme, called Power Adapted Medium Access Control (PAMAC) scheme for achieving energy conservation, which allows a node to vary its own transmit power on a packet basis. The primary objective of this scheme is to use suitable transmit power level for Clear-To-Send (CTS), DATA, and Acknowledgement (ACK) that still allows to achieve a correct reception of a packet despite intervening path loss, noise and interference. The evaluation of the throughput efficiency per node, energy consumption per node and energy per successfully transmitted bit is performed by a computer simulation. Simulation results indicate that the proposed PAMAC scheme can achieve a high reduction of the energy consumption and energy per successfully transmitted bit and also an improvement in the throughput efficiency per node compared to the conventional Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) protocol.

In this paper, we propose a new error feedback (EF) structure for 2-D separable-denominator digital filters described by a rational transfer function. In implementing two-dimensional separable-denominator digital filters, the minimum delay elements structures are common. In the proposed structure, the filter feedback-loop corresponding to denominator polynomial is placed at a different location compared to the commonly used structures. The proposed structure can minimize the roundoff noise more than the previous structure though the number of multipliers is less than that of previous one. Finally, we present a numerical example by designing the EF on the proposed structure and demonstrate the effectiveness of the proposed method.

As the complexity of VLSI circuits increases, the routability problem becomes more and more important in modern VLSI design. In general, the flexibility improvement of the edges in a routing tree has been exploited to release the routing congestion and increase the routability in the routing stage. Given an initial rectilinear Steiner tree, the rectilinear Steiner tree can be transformed into a Steiner routing tree by deleting all the corner points in the rectilinear Steiner tree. Based on the definition of the routing flexibility in a Steiner routing tree and the timing-constrained location flexibility of the Steiner-point in any Y-type wire, the simulated-annealing-based approach is proposed to construct a better timing-constrained flexibility-driven Steiner routing tree by reassigning the feasible locations of the Steiner points in all the Y-type wires. The experimental results show that our proposed algorithm, STFSRT, can increase about 0.005-0.020% wire length to improve about 43-173% routing flexibility for the tested benchmark circuits.

Screen pattern used in offset-printed documents has been one of great obstacles in developing document recognition systems that handle color documents. This paper proposes a selective smoothing method for filtering the screen patterns/noise in high-resolution color document images. Experimental results show that the method yields significant improvements in character pattern extraction.

In order to miniaturize a very low-level dc current amplifier and to speed up its output response speed, we proposed to employ the switched-capacitor circuit (SCC) as its negative feedback circuit, instead of the conventionally used high-ohmage resistor. However, in the case of using SCC, the output waveform had unnecessary components. To decrease the effect of these components and to speed up the response speed, we used a switched-capacitor filter (SCF), an offset controller, and a positive feedback circuit. As a result, we demonstrated that it was useful to use the amplifier using the SCC.

According to the proliferation of ubiquitous computing, various products which contain large-size embedded software have been developed. One of most typical features of embedded software is concurrency of software and hardware factors. That is, software has connected deeply into hardware devices. The existence of various hardware make quality assurance of embedded software more difficult. In order to assure quality of embedded software more effectively, this paper discusses features of embedded software and an effective method for quality assurance for embedded software. In this paper, we first analyze a failure distribution of embedded software and discuss the effects of hardware devices on quality of embedded software. Currently, in order to reduce hardware related faults, huge effort for testing with large number of test items is required. Thus, one of the most important issues for quality assurance of embedded software is how to reduce the cost and effort of software testing. Next, focusing on hardware constraints as well as software specifications in embedded software, we propose an evaluation metrics for determinating important functions for quality of embedded software. Furthermore, by referring to the metrics, undesirable behaviors of important functions are identified as root nodes of fault tree analysis. From the result of case study applying the proposed method to actual project data, we confirmed that test items considering the property of embedded software are constructed. We also confirmed that the constructed test items are appropriate to detect hardware related faults in embedded systems.

It is not always possible to find a global parse for an input sentence owing to problems such as errors of a sentence, incompleteness of lexicon and grammar. Partial parsing is an alternative approach to respond to these problems. Partial parsing techniques try to recover syntactic information efficiently and reliably by sacrificing completeness and depth of analysis. One of the difficulties in partial parsing is how the grammar might be automatically extracted. In this paper we present a method of automatically extracting partial parsing rules from a tree-annotated corpus using the decision tree method. Our goal is deterministic global parsing using partial parsing rules, in other words, to extract partial parsing rules with higher accuracy and broader expansion. First, we define a rule template that enables to learn a subtree for a given substring, so that the resultant rules can be more specific and stricter to apply. Second, rule candidates extracted from a training corpus are enriched with contextual and lexical information using the decision tree method and verified through cross-validation. Last, we underspecify non-deterministic rules by merging substructures with ambiguity in those rules. The learned grammar is similar to phrase structure grammar with contextual and lexical information, but allows building structures of depth one or more. Thanks to automatic learning, the partial parsing rules can be consistent and domain-independent. Partial parsing with this grammar processes an input sentence deterministically using longest-match heuristics, and recursively applies rules to an input sentence. The experiments showed that the partial parser using automatically extracted rules is not only accurate and efficient but also achieves reasonable coverage for Korean.

The reflection characteristics of large alternating-phase fed single-layer waveguide arrays with center-feeds are investigated to identify the mechanism for bandwidth narrowing effects. Firstly, the overall reflection for the whole array is analyzed by FEM and fine agreement with measurements is demonstrated. It is deviating from the conventional prediction based upon a simple sum of reflections from components in the array, such as the multiple-way power divider, the slot waveguides and the aperture at the antenna input. Careful diagnosis reveals that the mutual coupling between the alternating phase waveguides via external half-space is the key factor in reflection accumulation. Amongst all, the slot with strong excitation whose position depends upon the aperture illumination design produces the dominant contribution in the mutual coupling.

A method is presented for the simultaneous measurement of the absolute gain of antennas in solution and the dielectric properties of the solution. The principle and formulation are based on a modified Friis transmission formula. This three-antenna method is applied to gain measurement of printed dipole antennas in solution, and demonstrated through comparison with calculated results to be an accurate method for the measurement of both antenna gain and solution dielectric properties.

Investment planning for power plants involves making a long-term plan covering various facility investments, such as the construction of a new power plant or the replacement of an old plant with a new one, under uncertain environments. In this paper, we propose an optimization method for such a planning problem. Our method is based on decision tree analysis, in which uncertain environments are described as scenarios. The maintenance of existing plants is also taken into account by introducing the option of large-scale repair in addition to replacement. In order to avoid combinatorial explosion of failure event scenarios of plants, we introduce the concept of failure risk cost which contributes to simplification of the decision tree and reduction of the calculation time.

We present a method of stabilizing a class of nonlinear systems which are not necessarily feedback linearizable. First, we show a new way of constructing a diffeomorphism to transform a class of nonlinear systems to the feedback linearized form with perturbation. Then, we propose a semi-globally stabilizing control law for nonlinear systems that are connected by a chain of integrator perturbed by arbitrary nonlinear terms. In our approach, we have flexibility in choosing a diffeomorphism where the system is not restricted to involutivity and this leads to reduction in computational burden and flexibility in controller design.

Continuous and explosive growth of the Internet has shown that current TCP mechanisms can obstruct efficient use of high-speed, long-delay networks. To address this problem we propose an enhanced transport-layer protocol called gHSTCP, based on HighSpeed TCP proposed by Sally Floyd. It uses two modes in the congestion avoidance phase based on the changing trend of RTT. Simulation results show gHSTCP can significantly improve performance in mixed environments, in terms of throughput and fairness against the traditional TCP Reno flows. However, the performance improvement is limited due to the nature of TailDrop router, and the RED/ARED routers can not alleviate the problem completely. Therefore, we present a modified version of Adaptive RED, called gARED, directed at the problem of simultaneous packet drops by multiple flows in high speed networks. gARED can eliminate weaknesses found in Adaptive RED by monitoring the trend in variation of the average queue length of the router buffer. Our approach, combining gARED and gHSTCP, is quite effective and fair to competing traffic than Adaptive RED with HighSpeed TCP.

The present paper describes a quality enhancement of band-limited speech signals. In regular telephone communication, the quality of the received speech signal is degraded by band limitation. We propose an effective but simple scheme for obtaining narrowband speech signals in which the frequency components are estimated from band limited signals. The proposed method utilizes aliasing components generated by wavelet reconstruction filters in the inverse discrete wavelet transform. The results of enhancement have been verified by applying this method to speech samples via telephone lines to obtain a noticeable improvement in speech quality.

A peer-to-peer (P2P) Contents Delivery Network (CDN) is a system in which the users get together to forward contents so that the load at a server is reduced. Lately, we have high-speed services for an access to the Internet such as the Asymmetric Digital Subscriber Line (ADSL). Some broadcasters may not have such services because they have only dial-up services and wireless services as PHS and a mobile phone to broadcast live. A problem with P2P CDN is its overhead to construct a distribution tree. It becomes a crucial problem when a broadcaster has only a low-speed access to the Internet, and we propose a P2P CDN system which reduces such an overhead. A server peer is the root peer of a distribution tree and provides users with contents. With the existing algorithms, new peers measure a Round Trip Time (RTT) and a throughput from a broadcaster site when they join the distribution tree. With our algorithm, a new peer sends the server peer a Search Request message which is forwarded throughout the distribution tree until a suitable peer which has enough bandwidth to accomodate is found finally so that the new peer will measure a throughput to that peer. The problem with our algorithm is that as the number of users in the tree increases, the new peer will be preoccupied with measurement, because it may find many suitable peers as its parent candidates. To solve this problem, we introduce a Time To Stop Broadcast (TTSB) on the Search Request message in order to reduce the number of measurement. We have compared the traditional algorithm with ours by simulation. From the simulation results, we have found that our method is effective when a server peer has a low-speed access to the Internet, while the users have a high-speed access.

There have been many arguments that the underlying structure of natural languages is beyond the descriptive capacity of context-free languages. A well-known example is tree adjoining grammars; less common are spine grammars, linear indexed grammars, head grammars, and combinatory categorial grammars. It is known that these models of grammars have the same generative power of string languages and fall into the class of mildly context-sensitive grammars. For an automaton, it is known that the class of languages accepted by transfer pushdown automata is exactly the class of linear indexed languages. In this paper, deterministic transfer pushdown automata is introduced. We will show that the language accepted by a deterministic transfer pushdown automaton is generated by an unambiguous spine grammar. Moreover, we will show that there exists an inherently ambiguous language.