bluuebunny/crossref_metadata_2025 huggingface dataset:
Peroxiredoxin V in multiple sclerosis lesions: predominant expression by astrocytes
Authors: Holley J.E. , Newcombe J. , Winyard P.G. , Gutowski N.J.
Published: July 2007

Oxidative stress is implicated in the pathogenesis of multiple sclerosis (MS). Defence against oxidative damage is mediated by antioxidants. Peroxiredoxin V (PRDX V) is an intracellular anti-oxidant enzyme with peroxynitrite reductase activity. It is increased during inflammation, when free radical production intensifies, and is protective in an animal model of brain injury. However, little is known about PRDX V expression in the human brain. We investigated PRDX V expression in white matter from normal human brain ( n = 5) and MS patients ( n = 18), using immunohistochemistry and immunoblotting. A global increase in PRDX V was evident in MS normal-appearing white matter (NAWM) but the most striking increase was in astrocytes in MS lesions. PRDX V- positive hypertrophic reactive astrocytes were seen in acute lesions where inflammation was present. Yet surprisingly, in chronic lesions (CL), where inflammation has abated and a glial scar formed, there was strong PRDX V staining of post-reactive, scar astrocytes. Furthermore, immunoblotting analysis of tissue from two MS cases confirmed a substantial increase in PRDX V expression in CL compared with NAWM from the same individual. This might indicate ongoing oxidative stress despite the absence of histologically defined inflammation. Further investigations of this phenomenon will be of interest for therapeutic targeting. Multiple Sclerosis 2007; 13: 955—961. http://msj.sagepub.com
Theoretical Design of a Molecular Switch with Controlled Hydrogen Bonds: Electronic and Vibrational Spectra of [Co(2,2′-biimidazole)(C6H4O2)(NH3)2]2
Authors: Mori Hirotoshi , Miyoshi Eisaku
Published: July 2007

The electronic and vibrational spectra of a proton–electron-coupled inorganic complex [Co(Hbim)(C6H4O2)(NH3)2]2 having multistable states, were theoretically investigated using density functional theory calculations using B3LYP parameters. The electronic excitation spectrum in the low-spin ground 1Ag state of the complex has no strong absorption in the visible region (600–700 nm), while in the high-spin 5A1 and 9Ag complexes, some prominent peaks were predicted in the visible region. Frequency analyses of the 1Ag, 5A1, and 9Ag states showed the strong band of the NH stretching vibration at 2690, 2120, and 2770 cm−1, respectively. Based on this, it is possible to distinguish 5A1 from 1Ag and 9Ag by measuring IR light absorption at 2120 cm−1, showing that [Co(Hbim)(C6H4O2)(NH3)2]2 would be a good candidate for use as optically durable molecular level memory.
Predicting the risk of a false-positive test for women following a mammography screening programme
Authors: Njor Sisse Helle , Olsen Anne Helene , Schwartz Walter , Vejborg Ilse , Lynge Elsebeth
Published: July 2007

Objectives: The objectives of this study was to provide a simple estimate of the cumulative risk of a false-positive test for women participating in mammography screening. To test the method, we used data from two well-established, organized mammography screening programmes offering biennial screening to women aged 50–69 years in Copenhagen and Fyn, Denmark.

Methods: We defined the outcome from a screen as being either a false-positive test or not a false-positive test. We then tested whether the outcomes from subsequent screens were independent, and afterwards estimated the risk over 10 screens of a false-positive test, i.e. the risk of getting at least one false-positive test for a woman participating in all 10 screens typically offered in Europe.

Results The outcomes of subsequent screens were found to be independent. After completion of screening rounds 3–5, the risk of a false-positive test over 10 screens was predicted to be 15.8–21.5% for a woman participating in the programme in Copenhagen, and 8.1–9.6% for a woman participating in the programme in Fyn.

Conclusions Our study showed that a relatively robust prediction of the risk of a false-positive test over 10 screens can be calculated in a simple way relatively early after the start of a mammography screening programme.
Diversity, abundance and distribution of macroalgae at Sirinart Marine National Park, Phuket Province, Thailand
Authors: Thongroy Pimonrat , Liao Lawrence M. , Prathep Anchana
Published: July 2007

Diversity, abundance and distribution of intertidal macroalgae were investigated in relation to environmental conditions (site, shore level, salinity, temperature, NO3-and) in Sirinart Marine National Park, Phuket province, Thailand, from January to November 2004. The shores were divided into 3 categories by shore level: upper, mid and lower shores; and 3 sampling sites: sites 1, 2 and 3. A total of 52 species of macroalgae were recorded. Nine species are considered to be new records for the Thai marine flora. The average diversity index of macroalgae differed slightly among sites: 0.92±0.07 (mean±SE), 1.00±0.13 and 0.94±0.16 for site 1, site 2 and site 3, respectively. There was significant difference in abundance of macroalgae among sites and seasons.Lyngbya majusculaandPadina australiswere the most abundant species. Their percentage covers were 31.66±7.21% and 27.77±4.67% in site 2 at mid shore level during March 2004 and in site 3 at mid shore level during November 2004, respectively.
Filament formation and differentiation in seven species of red algae
Authors: Yan Yin Ming , Yan Hu Xiao , Kui Tseng Cheng
Published: July 2007

Filaments were induced from cut edges of segments of Gloiosiphonia capillaris, Gloiopeltis furcata, Chondrus ocellatus, Solieria tenuis, Ceramium kondoi, Chondria tenuissima, Laurencia okamurai and from the intact surfaces of Ceramium kondoi and Chondria tenuissima under unialgal culture conditions. The filaments of Gloiosiphonia capillaris can grow vegetatively under free-living conditions, while filaments of Gloiopeltis furcata tended to differentiate after excision from explants and grew autotrophically to the 10- to 20-cell stage. Filaments of other species usually survived attached to generating explants. Two distinct modes of filament regeneration were discerned among the species. In Gloiosiphonia capillaris, Gloiopeltis furcata, Chondrus ocellatus and Solieria tenuis, filaments initially developed into crust or crust-like compact tissue in suspension culture; upright thalli developed from the crusts. In Ceramium kondoi, Chondria tenuissima and Laurencia okamurai, thalli were generated from pseudoparenchyma that was developed from filaments, while creeping parts (rhizoids) formed a prostrate system.
An Early Critical Period for Long-Term Plasticity and Structural Modification of Sensory Synapses in Olfactory Cortex
Authors: Poo Cindy , Isaacson Jeffry S.
Published: July 2007

Critical periods for plasticity of thalamic sensory inputs play an important role in developing neocortical circuits. During an early postnatal time window, pyramidal cells of visual, auditory, and somatosensory cortex undergo structural refinement and possess an enhanced ability for activity-dependent synaptic plasticity. In olfactory cortex, however, pyramidal cells receive direct sensory input from the olfactory bulb, and it is unclear whether the development of olfactory sensory circuits is governed by a critical period. Here, we show that NMDA receptor-dependent long-term potentiation and dendritic spine maturation occur only during a brief postnatal time window at sensory synapses of olfactory cortex pyramidal cells. In contrast, associational synapses onto the same cells retain the capacity for plasticity into adulthood.
Management of a cooperative cache in grids with grid cache services
Authors: Cardenas Yonny , Pierson Jean‐Marc , Brunie Lionel
Published: July 2007

Distributed systems like grids support diverse models of distributed computation and need to operate large data entities in a distributed way. A significant quantity of this data are used only for a limited period of time. Caching is recognized as one of the most effective techniques to manage temporary data and collaborative cache is traditionally proposed to scale cache capabilities in distributed environments. Grid needs to manage dynamically different models of computation with different data access patterns. In this paper, we propose a basic infrastructure for the management of collaborative caches that permits to operate and control dynamically different cache mechanisms and cache schemes in grid. Beside traditional collaborative caching where the cooperation is often limited to data resolution, in our infrastructure the collaborative cache capacities are extended to operate and manage these distributed temporal data. Our proposition is composed of a reference cache model that defines four layers for the management of collaborative cache; an information model that represents the main cache elements and their activity; and a set of operations to request specific tasks to monitor, operate, and coordinate a generic collaborative cache system. Implementation issues of a prototype in Globus Toolkit 4 are discussed. Copyright © 2007 John Wiley & Sons, Ltd.
Self‐Similar Gas Motion Near The Evaporating Electrode of An Electric Arc
Authors: Djakov B. E.
Published: July 2007

Simple solutions of 1Dt gas‐dynamical equations based on similarity analysis are possible for the gas surrounding a point source of mass and energy such as an electrode (cathode) arc spot. To obtain nontrivial (non‐zero temperature) solutions throughout, two‐scale formulation is used that permits an additional boundary condition near the source. Three generalised gas flow variables, R, Z and V, related to gas density, temperature and velocity are calculated and presented as functions of a single similarity parameter, λ, related to position and time. The computational results are compared with data from two gas discharge experiments: on gas disturbances due to an electric arc of micrometer length in atmospheric air and on expansion of a metal‐vapour plasma cloud generated by a low‐pressure cold‐cathode arc.
Optically Active Thin Films Deposited by Plasma Polymerization of Dye Molecules
Authors: Barranco A. , Aparicio F. , Yanguas‐Gil A. , Groening P. , Cotrino J. , González‐Elipe A. R.
Published: July 2007

Colored and fluorescent thin films are prepared via polymerization of dye molecules by interaction with a remote plasma of Ar while they are sublimated on a substrate. The films are formed by a crosslinked matrix of fragments of the original dye and some unreacted molecules. Films made of Ethyl Red or Rhodamine 6G dyes are characterized and studied with regard to their optical properties. Plasma characterization by optical emission spectroscopy (OES) shows the fragmentation of the evaporated dye molecules by interaction of the dye molecules with the electrons of the plasma. The electron energy seems to be the main parameter controlling the polymerization degree of the films. The process is very interesting for the deposition of thin films containing functional molecules.
Low‐Pressure PECVD of Nanoparticles in Carbon Thin Films from Ar/H2/C2H2 Plasmas: Synthesis of Films and Analysis of the Electron Energy Distribution Function
Authors: Camero M. , Gordillo‐Vázquez F. J. , Gómez‐Aleixandre C.
Published: July 2007

A study of the synthesis of carbon nanoparticles embedded in carbon thin films deposited by radiofrequency (RF) (13.56 MHz) Ar/H2 (4 %)/C2H2 plasmas is presented. The carbon nanospheres exhibit an amorphous structure that is clearly observed at 300 W, under 0.1 Torr, and grows in size with increasing C2H2 between 1 % and 20 %. Above a C2H2 concentration threshold (20 % in this case) carbon nanoparticles are no longer formed. In order to study possible changes in the plasma kinetics, optical emission spectroscopy (OES) is used to evaluate the electron temperature while changing the C2H2 concentration. In addition, an analysis of the temporal evolution of the electron energy distribution function (EEDF) is carried out for various C2H2 concentrations considering the effects produced by electron‐vibrational superelastic collisions and relative concentration of excited Ar atoms. Finally, the morphological and tribological features of the deposited films are characterized.
Nonthermal Plasma Synthesis of Faceted Germanium Nanocrystals
Authors: Cernetti P. , Gresback R. , Campbell S. A. , Kortshagen U.
Published: July 2007

Low‐pressure plasmas are known for their ability to synthesize nanoparticles via gas‐phase nucleation. While in the past this particle formation has often been considered from the viewpoint of a contamination problem in semiconductor processing, we here describe a low‐pressure plasma that enables the synthesis of faceted germanium nanocrystals. The germanium nanocrystals are generally single crystals without any planar defects such as twin boundaries. A change in the morphology with particle size is observed. Small germanium particles up to about 30 nm in size are mostly cubes with (100) crystal facets. Larger crystals between 30–60 nm are primarily cuboctahedrons. Even larger nanocrystals are mainly spherical. The shape evolution is interpreted in terms of the equilibrium shape of hydrogen‐coated germanium crystals. Possible applications of these crystals are discussed.
In Situ Monitoring of Silicon Plasma Etching Using a Quantum Cascade Laser Arrangement
Authors: Stancu G. D. , Lang N. , Röpcke J. , Reinicke M. , Steinbach A. , Wege S.
Published: July 2007

In etch plasmas used for semiconductor processing, concentrations of the precursor gas NF3 and of the etch product SiF4 are measured online and in situ using a new diagnostic arrangement, the Q‐MACS Etch system, which is based on quantum cascade laser absorption spectroscopy (QCLAS). In addition, the etch rates of SiO2 layers and of the silicon wafer are monitored including plasma‐etching endpoint detection. For this purpose the Q‐MACS Etch system is working as an interferometer arrangement. The experiments are performed in an industrial, dual‐frequency, capacitively coupled, magnetically enhanced, reactive ion etcher (MERIE), which is a plasma reactor developed for dynamic random access memory (DRAM) technologies. In the spectral range 1028 ± 0.3 cm–1, the absorption cross‐sections of SiF4 and NF3 are determined to be σ = (7.7 ± 0.7) × 10–18 cm2 molecule–1 and σ = (8.7 ± 0.8) × 10–20 cm2 molecule–1, respectively.
Cytometry of ATM activation and histone H2AX phosphorylation to estimate extent of DNA damage induced by exogenous agents
Authors: Tanaka Toshiki , Huang Xuan , Halicka H. Dorota , Zhao Hong , Traganos Frank , Albino Anthony P. , Dai Wei , Darzynkiewicz Zbigniew
Published: July 2007

This review covers the topic of cytometric assessment of activation of Ataxia telangiectasia mutated (ATM) protein kinase and histone H2AX phosphorylation on Ser139 in response to DNA damage, particularly the damage that involves formation of DNA double‐strand breaks. Briefly described are molecular mechanisms associated with activation of ATM and the downstream events that lead to recruitment of DNA repair machinery, engagement of cell cycle checkpoints, and activation of apoptotic pathway. Examples of multiparameter analysis of ATM activation and H2AX phosphorylation vis‐a‐vis cell cycle phase position and induction of apoptosis that employ flow‐ and laser scanning‐cytometry are provided. They include cells treated with a variety of exogenous genotoxic agents, such as ionizing and UV radiation, DNA topoisomerase I (topotecan) and II (mitoxantrone, etoposide) inhibitors, nitric oxide‐releasing aspirin, DNA replication inhibitors (aphidicolin, hydroxyurea, thymidine), and complex environmental carcinogens such as present in tobacco smoke. Also presented is an approach to identify DNA replicating (BrdU incorporating) cells based on selective photolysis of DNA that triggers H2AX phosphorylation. Listed are strategies to distinguish ATM activation and H2AX phosphorylation induced by primary DNA damage by genotoxic agents from those effects triggered by DNA fragmentation that takes place during apoptosis. While we review most published data, recent new findings also are included. Examples of multivariate analysis of ATM activation and H2AX phosphorylation presented in this review illustrate the advantages of cytometric flow‐ and image‐analysis of these events in terms of offering a sensitive and valuable tool in studies of factors that induce DNA damage and/or affect DNA repair and allow one to explore the linkage between DNA damage, cell cycle checkpoints and initiation of apoptosis. © 2007 International Society for Analytical Cytology
Performance analysis of an adaptive receiver structure for digital mobile communications
Authors: Lombardi C. , Luise M. , Reggiannini R.
Published: July 2007

In this paper we investigate the performance of a combined estimation/equalization technique for the mobile radio channel, assuming a GSM‐recommended transmission format (narrowband TDMA with midamble, recommendation 5.04) and MSK modulation scheme.

Channel estimation is performed via correlation of the received signal with a suitably modulated replica of the transmitted midamble. Equalization is then obtained by means of a maximum likelihood sequence estimation (MLSE) scheme in the form of a so‐called Viterbi equalizer.

Our analysis provides theoretical results concerning the bit error rate (BER) attained by the receiver for a given stationary multipath channel model. Simulation results are also presented in order to integrate and validate the theory.
International standards for the broadband ISDN user‐network interface
Authors: Anderson Jon
Published: July 2007

Recently, a series of international standards on broadband ISDN were approved in CCITT Study Group XVIII. These standards establish fundamental details on transmission, multiplexing and switching for broadband aspects of ISDN. This article reports on the current definition of the BISDN user‐network interface. The UNI reference configuration, physical medium, rates, structure, ATM functions, and operations and maintenance functions are addressed with consideration given to open issues and the direction of future standards activities. Objectives for the UNI capabilities have generally been met with the current CCITT specifications. Some of the UNI physical layer ‘options’, however, potentially impose networking cost penalties.
Generation of m‐sequences over GF(q2) from m‐sequences over GF(q)
Authors: Komo John J. , Lam Maurice S.
Published: July 2007

A closed form solution that yields the component shift required for the vector representation of m‐sequences over GF(q2) in terms of m‐sequences over GF(q2) is presented. Iterative application of this expression then enables the vctor representation of m‐sequences over GF(q2m) in terms of m‐sequences over GF(q). These vector m‐seqeences can be used directly for the selection of frequencies in frequency hopped spread spectrum communication systems.
Design method for high‐precision monolithic quartz crystal filters
Authors: Kobayashi Masaki
Published: July 2007

This paper proposes a method of designing high‐precision monolithic quartz crystal filters (MCFs). the realization of MCFs is inhibited by: (a) the frequency‐dependence of the coupling characteristics of the resonators; and (b) the distortion of the resonance characteristics of the resonators. These are both related to the arrangement of the eigenfrequencies of the filter, and they deviate the actual values from the designed values. the modes of additional phase‐inverting electrodes (phase inverter) of the MCFs are considered in this paper. For the forementioned (a), the conditions of the structure of the phase inverter are deduced which minimize the frequency‐dependent variation of a gyrator equivalently representing the mechanical coupling of the resonator. For (b), the conditions of the structure of the resonator which satisfy the second‐degree series resonance characteristics are deduced. the effect of the conditions for the structures is examined by computer simulation, and the design method of filters is shown. the proposed filter is compared with conventional MCFs from the viewpoint of the arrangement of the eigenfrequencies so that the usefulness of the proposed method is demonstrated.
Iterative technique for designing IIR filters with arbitrary log‐magnitude function
Authors: Kobayashi Takao , Imai Satoshi
Published: July 2007

This paper proposes an iterative approximation technique of log‐magnitude response for IIR filters. Minimization of the mean‐square error between a desired log‐frequency response and that of an IIR filter leads to a nonlinear problem. In this paper, the least squares problem on the logarithmic scale is approximated by the iteration of a weighted least squares problem on the linear scale. the weighting function is updated using the result of the previous iteration so that the weighted error on the linear scale approximates the squared error on the logarithmic scale. the filter coefficients at each iteration step can efficiently be obtained using a fast recursive algorithm for a set of linear equations. Several design examples are presented, which show that the iterative algorithm converges after one or two iterations in practice and the weighted error at convergence gives a good estimate of the mean‐square error on the logarithmic scale. an example is also presented, where both log‐magnitude and phase responses are approximated simultaneously.
Three‐state compound channel models
Authors: Suematsu Toshinari , Imai Hideki
Published: July 2007

This paper considers the qualitative or quantitative properties of the data errors generated on the digital channel or recording medium, and the construction of the statistical model which generates the errors with the same property as that of the actual errors. This is one of the important problems in the evaluation and design of the devices (especially those for error‐correction). the traditional statistical model for such a purpose is based on the Markov chain, for which a number of studies have been made. Typical examples are the Gilbert model, the Fritchman model and the extended Gilbert model. This paper extends those models further and presents several new three‐state compound channel models. These models have some very interesting properties which have not been observed in earlier models. For example, it is possible to generate a larger number of paired errors or burst errors of specified length. This paper describes first the features of those models and then constructs them. an example is given in which the model parameters are determined from the error data measured from an optical disk.
An efficient coding using the correlation between time series of differential LSP parameters
Authors: Arai Shuichi , Ozawa Shinji
Published: July 2007

The information compression by LSP analysis‐synthesis is a promising method in the sense that speech with relatively high quality can be synthesized with a small number of codes. Up to now, coding of LSP parameters has been investigated from various viewpoints. LSP analysis is performed framewise independently, while rarely does the speech information change rapidly with time. Consequently, when viewed as a time‐series, LSP parameters contain redundancies. On the other hand, LSP parameters are ordered in the ascending order of the frequency, and the time‐series exists for each parameter. A correlation exists between two time‐series which are adjacent on the frequency axis. From those viewpoints, this paper examines first the statistical features of LSP parameters when viewed as the time‐series. the coding based on those features is proposed, and the essential usefulness of the method is verified experimentally. Then, a new highly efficient coding method is proposed by combining the two foregoing ideas. In the proposed method, the interframe difference of LSP parameters is encoded in the first stage, which can reduce the coding complexity.

In the second stage, the coding complexity required for transmission is reduced further by encoding the difference of the time‐series adjacent on the frequency axis. Applying the proposed system, coding experiment and the quality evaluation of synthesized speech were performed, and the validity of the proposed method was confirmed.
Restriction on realization of single‐amplifier impedance‐converter and its application to LCR filter simulation
Authors: Fujii Nobuo , Yanagisawa Takeshi
Published: July 2007

This paper proposes a method to realize single‐amplifier impedance converters (SAICs), while a conventional general impedance converter (GIC) for an active RC filter requires two operational amplifiers. First, various restrictions required for realizing an SAIC were investigated. Then a method of realizing an SAIC was described which utilizes the property of a grounded active RC two‐port circuit having an impedance‐conversion effect; and the SAIC was applied to the simulation of an LCR filter. an SAIC can approximately simulate an arbitrary circuit with some restricted circuit constants, although the range of circuits which can be simulated exactly is limited. As examples, an asymmetrical sixth‐order BPF and a symmetrical sixth‐order BPF were constructed and their experimental results agreed well with the theoretical values.
Max‐flow min‐cut theorem for the multicommodity flows in certain planar directed networks
Authors: Nagamochi Hiroshi , Ibaraki Toshihide
Published: July 2007

Classes CB, CS and CU have been found as the classes of networks, for which there exist efficient graph‐theoretical algorithms for the multicommodity flow problem on the directed network. This paper shows that the max‐flow min‐cut theorem holds for classes CB and CS. In other words, in those networks, if the multicommodity flow is not feasible, there always exists a cut for a source‐and‐sink pair, indicating the unfeasibility of the flow. For class CU, an example has already been presented where the max‐flow min‐cut theorem does not hold.
Synthesis of a flow network with a given centrality on each vertex
Authors: Takeuchi Masashi , Kishimoto Wataru , Kishi Genya
Published: July 2007

This paper considers the problem of constructing a flow network when the centrality at each vertex is given. Here, attention is given to a centrality function such that the centrality at a vertex under consideration is the sum of maximum flow values between it and all other vertices. It is a representative centrality function among those representing the centrality of each vertex in an undirected flow network in which edges have capacity. First, we introduce a necessary and sufficient condition wherein a given sequence is a centrality sequence for a flow network. Next, we present a procedure for determining a terminal capacity matrix of a flow network with a given centrality sequence. Furthermore, we determine a terminal capacity matrix of a flow network with a given centrality sequence such that the sum of edge capacity is minimum. From these discussions we can see that the problem of constructing a flow network when a centrality is given, can be reduced to the previously known problem of constructing a flow network when a terminal capacity matrix is given.
A new structure of prefilters for FIR digital filters
Authors: Aikawa Naoyuki , Sato Masamitu
Published: July 2007

The cascade of a prefilter and an equalizer is effective for realizing an FIR digital filter with few multipliers. Generally, the number of multipliers in the entire filter decreases as the prefilter response becomes closer to a given specification. This paper proposes a new structure of pre‐filters which can produce a response closer to the specification than a conventional structure. Furthermore, a new method of cascading the prefilters, and which improves both the passband and stopband characteristics, is described. In this method, a pre‐filter cascaded with the preceding ones is designed so as to compensate their approximate characteristics. the small passband ripple and large stopband attenuation can be realized by using the proposed prefilters and an equalizer with only few multipliers.
A new DSP‐oriented FFT algorithm
Authors: Mikami Naoki , Matsuoka Masahiro
Published: July 2007

In the traditional fast‐Fourier trans form (FFT) algorithm, the design for high‐ speed operation is made based on the number of operations, especially the number of multiplications, which is time‐consuming in the general‐purpose processor. This is not necessarily reasonable in the digital signal processor (DSP), where the multiplication can be performed in the time equal to that of other operations. From such a viewpoint, this paper proposes an algorithm which matches the feature of DSP, where the pro cessing is fast when the multiply‐accumulate operations are continued in execution. the algorithm is applicable when the number of data IV can be factorized into mutually prime factors. DFT for smaller number (factor) of data is modified into the cyclic convolution, and is executed at a high speed (small‐ N algorithm). the proposed algorithm is composed of the small‐N algorithms and DFT for a large number of data (multidimensional algorithm), which combines small‐N algorithms into a multidimensional DFT. the number of operations is not necessarily reduced in the proposed algorithm, compared with the traditional FFT, but it was verified by an actual run of the program on DSP that the execution time is reduced.
Pitch synchronous Mel inverse LSP analysis‐synthesis technique of LPC voiced residual
Authors: Mano Atsushi , Ozawa Shinji
Published: July 2007

This paper proposes the pitch synchro nous mel inverse LSP analysis‐synthesis technique as a new coding method for LPC voiced residual. the pitch synchronous amplitude spectrum of the voiced residual has characteristic zeros. By applying the inverse LSP analysis in mel domain to this spectrum, the spectrum can be encoded with a high efficiency with order of analysis as small as 12. Then mel LSP inverse filter is proposed which can synthesize directly the voiced residual in the time domain from the mel LSP coefficients. It is shown that the voiced residual can easily be synthesized. For the voiced residual obtained from the forementioned analysis‐synthesis system, the order of the model formel inverse LSP analysis, quantization characteristics and the interpolation performance were investigated, with the mean spectrum distortion of mel pitch synchronous amplitude spectrum as the evaluation measure. the optimization of each parameter was discussed. A pitch synchronous mel inverse LSP analysis‐synthesis system was constructed based on the obtained result. A subjective quality evaluation was made for the synthesized speech, and it was verified that a high‐quality speech can be synthesized at 4.8 kbit/s. These results indicate that the proposed method is applicable with merits to the low bit‐rate vocoder.
Synthesis of LDI digital filters based on symmetrical lattice network simulation
Authors: Iwakura Hiroshi , Niwa Hiroki
Published: July 2007

It is important to realize a low‐sensitivity digital filter, from the view point of economy such as hardware complexity, for which numerous studies have been made. From those studies it is known that the digital filter simulating the analog network, such as leapfrog and wave digital filters, exhibit low coefficient‐sensitivity characteristics. This paper is based on the symmetrical lattice reactance network. It is shown that the required transfer function is given as the output difference between the doubly resistively terminated IX ladder networks constructed with two kinds of one‐port LC reactance elements as the series elements. A method to construct a digital filter is proposed by the leapfrog structure using LDI. the digital filter constructed by the proposed method requires a fewer number of elements. the operating transfer function and the return‐ loss function are realized simultaneously. It is shown by examples that compared with the traditional method based on the simulation of the analog network, almost comparable passband characteristics can be realized.
Use of generalized cepstral distance measure in isolated word recognition
Authors: Kobayashi Takao , Kondo Shun‐Ichi , Imai Satoshi
Published: July 2007

This paper proposes a generalized cepstral discance measure based on minimum phase spictral models and shows the performance of the distance measure for isolated word recognition. the generalized cepstral distance measure approximates the L2 norm between two spectra on a fractional power magnitude scale. the measure is equal to the cepstral distance measure for the special case. Calculation of the distance can be performed efficiently from cepstral coefficients or linear predictor coefficients. Isolated word recognition experiments using a vocabulary of 20 highly confusable Japanese city names indicate that the generalized cepstral distance measure gives higher recognition accuracy than conventional distance measures. Three analysis parameter sets, which are FFT cepstral coefficients, linear predictor coefficients, and improved cepstral coefficients, are also compared in terms of their effects on the recognition performance.
A highly reliable trellis‐coded modulation using binary convolutional codes
Authors: Yamaguchi Kazuhiko , Imai Hideki
Published: July 2007

This paper proposes a coding scheme for multilevel channel coding, aiming at the high‐speed and highly reliable information transmission. the coding scheme is realized by combining binary convolutional codes. the scheme is based essentially on the idea of the coding by Imai‐Hirakawa's block code, and is implemented easily. Since the convolutional code and Viterbi decoding are em ployed, a high coding gain is realized. As an example, 2M level PSK with coding rate (M ‐ 1)/N and 2'M‐level QAM are presented. the result is compared with Ungerboeck's scheme, which is considered at present for practical application. It is shown that a larger coding gain is realized for the same har‐Iware scale. In the convolutional code, the coding scheme minimizing the decoding error probability for the given constraint length and the coding rate is called the optimal scheme. the proposed scheme is not the optimal in this sense. Consequently, the deviation from the optimal scheme is evaluated using the error exponent. it is shown that when the decoding error probability is set as constant, the implementation of the decoder is easier by the proposed method.
A chaotic circuit family including one diode
Authors: Saito Toshimichi
Published: July 2007

This paper considers the chaotic phenomena in a family of three‐dimensional autonomous circuits composed of R, L, C, ‐R (linear negative resistor) and one diode. First, a canonical equation is proposed which describes such a family of circuits. It is a piecewise‐linear equation containing one large parameter α. When a is sufficiently large, an idealization applies where the diode is regarded as a switch. This idealiza tion is valid theoretically. the equation is simplified to a system where the two‐ and three‐dimensional linear equations alternate. the one‐dimensional Poincaré mapping can be defined. the one‐dimensional mapping is formulated explicitly. the generation condition for the chaos is presented in the sense of Li‐Yorke. the condition is verified by an experiment corresponding to a circuit example for chaos generation.
Lyapunov stability of two‐dimensional digital filters
Authors: Hinamoto Takao , Hamanaka Takashi , Maekawa Sadao
Published: July 2007

This paper discusses first the Lyapunov stability based on the Fornasini‐Marchesini model, and derives the two‐dimensional Lyapunov stability condition. the derived condition is general in the sense that it includes as a special case, the traditional two‐dimensional Lyapunov stability based on the Roesser model. Then the necessary and sufficient condition for the forementioned condition is derived. A sufficient condition is shown for the limit‐cycle not to be generated by the overflow in addition, due to the finite word length. Finally, the filter design based on the derived stability condition is discussed.
Realization of leapfrog‐type switched capacitor filters using time‐shared operational amplifier
Authors: Iwakura Hiroshi
Published: July 2007

Switched capacitor filters (SCFs) have recently been used widely since they are suitable for integrated circuits. Most conventional SCFs require the same number of operational amplifiers (OPAs) as the orders of a filter circuit, and each OPA requires a considerable area of a chip and power dissipation compared with other components. Therefore, it is desirable to realize a filter circuit with fewer OPAs. A known method which satisfies these conditions is the leapfrogtype SCF which reduces OPAs to about half.

This paper proposes an SCF which can reduce OPAs further, by using a signal flow graph (SFC) with no delay‐free loop which is the necessary condition for realization of a digital filter. In the proposed method, an SFG is divided into several blocks so that each of them can be calculated independently. Then the blocks are calculated sequentially in the order which makes the calculation possible. In other words, a single OPA is time‐shared with multiphase clocks. This paper also proposes another method in which the same DFGs are divided into blocks so that a parallel operation is possible.
Variable threshold soft decision decoding
Authors: Yamaguchi Kazuhiko , Iizuka Hiroshi , Nomura Eiji , Imai Hideki
Published: July 2007

Soft decision decoding is a decoding method which tries to improve the error‐correcting capability by utilizing the information concerning the reliability of the received symbol. One of the soft decision decoding methods for practically useful block code, is APP (a posteriori probability) decoding applicable to the majority‐logic de‐codable code. In APP decoding, the error is decided for each symbol as in majority‐logic decoding. This paper proposes a new decoding method (variable threshold APP decoding), in which the error‐correcting capability is improved by controlling the order of error decisions in APP decoding. the performance is evaluated by simulation. As a result, it is shown that the variable threshold APP decoding exhibits better characteristics than APP decoding and approximate APP decoding both in bit error rate and block error rate. When, for example, the proposed decoding is applied to (73, 45) difference set cyclic code, a coding gain of 1.0 dB is obtained compared with the approximate APP decoding. In the proposed decoding method, the time required for decoding is increased, while the hardware scale is almost the same as that of the approximate APP decoding.
Second‐order switched capacitor filter block with two clock frequencies and its design
Authors: Takeda Yasuyoshi , Sato Chikara
Published: July 2007

A second‐order variable SC filter block with two clock frequencies has been studied. This block consists of two first‐order variable SC filters feedback connected. By changing the two clock frequencies independently, both the resonant frequency and the Q value can be adjusted. It is possible to fabricate a higher‐order variable SC filter with degrees of freedom by cascading several of the blocks presented here. Derivation of the difference equation, transfer function and design method of this second‐order variable SC filter block is the objective of this paper.
Robust model matching design method which ensures stability
Authors: Zhong Yi‐Sheng , Tagawa Ryozaburo , Eisaka Toshio
Published: July 2007

The design method entitled “robust model matching” was recently proposed for the design of practical robust control systems. By this method, if the overall system is stable, any desired robustness in the steady‐state and transient characteristics can be guaranteed in spite of parameter variations for minimum‐phase plants. However, when using this method it is always necessary to employ a trial‐and‐error process to ascertain stability. In this paper a robust model matching design method which guarantees stability is proposed for the case when the parameter variations are such that the plant remains a minimum‐phase plant without a change in the sign of the gain. Moreover, only the controlled variable and the operating quantity are measurable. By this approach, any desired robustness in the steady‐state and transient characteristics can be achieved while guaranteeing robust stability without the necessity of a trial‐and‐error process.

In this paper, first the necessary conditions a robust filter must fulfill to ensure stability are presented. Next, the degree relationships that certain polynomials concerning the model matching controlled must fulfill to design a robust filter are clarified. Further, it is proven that control system stability is ensured by the design of an appropriate robust filter without narrowing the class of realizable reference models. Finally, the proposed design method is set forth and an example design problem is given.
Experimental approximate solutions of nonlinear discrete oscillation with parametric excitation
Authors: Tanaka Toshiyuki
Published: July 2007

In the analysis of a discrete nonlinear system, one of the important problems is to derive a steady solution for the nonlinear difference equation characterizing the system. However, the study for the solution method of the difference system has not been sufficient, and examples of the methods being applied to the parametric oscillation are few. This paper presents a method which derives the steady solution for the quasi‐linear difference equation containing a periodic parametric excitation in its weakly nonlinear function with small parameter e. In this method the harmonic balance and the averaging methods used in the solution of the continuous nonlinear differential equation are applied to the discrete system. Since the nonlinear term in the equation is bounded by ε the discrete waveform in the steady state is almost sinusoidal. This paper presents numerical examples for the solutions by the two methods, assuming the solution as the discrete oscillation corresponding to the sinusoid of the continuous system. As a result, the same solution is obtained by either method. Comparing the result with the output waveform obtained directly by the numerical calculation for the fundamental equation, the validity of the approximate solution by the proposed method was verified.
Cycle breaking and longest path in channel routing problem
Authors: Shimamoto Takashi , Sakamoto Akio
Published: July 2007

Channel routing is one of the automatic routing techniques in LSI design. In the channel routing by trunk‐branch scheme, if a cycle exists in the relational graph between subnets, the trunk of a net must be divided to break the cycle. Reference [11] presented a method, which divides the trunk of a net at a terminal on the graph representing the routing requirement. the effectiveness and pseudo‐effectiveness of the method are defined. Through the discussion of the necessary and sufficient condition for the realizability of the division, a condition is derived for the routing requirement to be realized. This paper discusses the degree of freedom remaining in the trunk division (i.e., the connection of free arcs in the modification of the requirement graph). the effect of the degree of freedom on the final result, especially on the longest path in the requirement graph, is discussed. As a result, it is shown that if the trunk division satisfies a certain condition, it does not increase much the longest path length.
A block placement procedure using a force model
Authors: Onodera Hidetoshi , Tamaru Keikichi
Published: July 2007

The paper treats the problem of automatic placement of building blocks of different sizes. This problem arises frequently in automating the layout design of LSIs. In this paper, a method is described for finding a global placement taking into account the connectivity between blocks as well as dimensions of blocks and placing regions. A method is proposed to establish a force model such that attractive forces caused by the connectivity between blocks and repulsive forces caused by the block overlaps are exerted on the blocks, and to derive a placement result as a system equilibrium state. the placement procedure is as follows. We start with the initial placement obtained only by applying attractive forces caused by connectivity, and then add gradually repulsive forces which are calculated based on the actual overlapping area between blocks. As a result, block overlap is removed and thus we can obtain a global placement considering local shape fitness while taking connectivity between blocks in a global way. In this paper, we explain first an outline of the proposed algorithm and then describe details of the methods for realizing it, e.g., functional forms of repulsive force against overlapping area, increasing ratio of repulsive force, and calculation method for the block equilibrium position and block orientation. Finally, the experimental results using examples with 17 and 33 blocks to demonstrate the effectiveness of the proposed algorithm are explained.
Effects of harmonic waves on output characteristics of electromagnetic thickness‐sensor
Authors: Yamada Takayuki , Suzuki Isao
Published: July 2007

An electromagnetic sensor to measure the thickness of metallic objects (including rusty objects) was proposed previously by the authors. the effects of higher‐harmonic waves of the sensor output due possibly to a magnetic nonlinearity of an object, however, was not taken into account. This paper examines this effect in relation to the thickness of the object, and obtains the optimum measuring frequency and current considering a heat‐loss in the sensor at a very low frequency; these are about 0.7 Hz and about 60 mA, respectively. With the improved method, the measurable ranges of thickness of objects are 0.5 to 4.5 mm for steel plates, and 0.5 to 7.0 mm for casting plates, an improvement by a factor of 2.5.
Spatial correlation and probabilistic evaluation of fluctuations at two observation points in a diffuse sound field
Authors: Ohta Mitsuo , Nakasako Noboru
Published: July 2007

Fluctuations at two observation points in a diffused sound field vary with correlations. In actual acoustic measurements, a sound level meter with a time constant is often used for a white noise input with a frequency bandwidth. Hence, fluctuations of the sound intensity must be considered first. Numerous studies have been reported on the probability density function and the spatial correlation in a diffuse sound field. How‐ever, the former is limited to a single variate distribution while the latter is restricted to the linear correlation of fluctuations. In this paper, the joint probability distribution of the fluctuations of the sound intensity is derived first so that various linear and nonlinear correlation effects between the fluctuations at two observation points are found in connection with the well‐known T‐type probability distribution at in dividual observation point. the resultant distribution expression is a two‐variate joint T distribution for which the arbitrary frequency bandwidth of the input and the effects of square function and arbitrary time constant of the measurement device are reflected structurally in each statistical parameter. Further, to distinguish all correlations between fluctuations at the two observation points A and B, the conditional probability density function on the fluctuation at the point A is derived in the case where a conditioned level is set at the point B. Finally, the present method is applied to the fluctuation data of sound measured in a reverberant room so that the actual usefulness is confirmed.
A priority queue with two priority classes whose nonpriority class call has preemptive and nonpreemptive parts
Authors: Komatsu Masaharu
Published: July 2007

A priority queue with two priority class calls is analyzed. In this model, nonpriority call consists of three parts: preemptive‐repeat part, preemptive‐resume part, and non‐preemptive part. If a priority call arrives during the service of the preemptive‐repeat part, the preemptive‐resume part and the non‐preemptive part, the preemptive‐repeat different, the preemptive‐resume, and the nonpreemptive priority queueing disciplines are enforced, respectively. As an analytical result, characteristic equations of completion time, busy period, waiting time, system time and through out are derived. Also, from numerical examples, throughput and average waiting time characteristics are examined.