It often occurs in the acoustic environment that a specific signal is contaminated by the additional noise of non-Gaussian distribution type. In order to extract exactly the various statistical information of only specific signal from the observed noisy data, a stochastic signal processing by use of digital computer is essential. In this study, a stochastic method for estimating the probability function of the specific signal embedded in the additional noise is first theoretically proposed in a suitable form for the quantized level observation. Then, the effectiveness of the proposed method is experimentally confirmed by applying it to the observed data in the acoustic environment.

A Ge/Si structure grown by chemical vapor deposition (CVD) is angle-lapped and characterized by the micro-Raman spectroscopy. Near the interface, the phonon mode due to the Si-Ge bond is clearly observed, which indicates that a SiGe alloy is formed by the solid-phase interdiffusion at the interface. The thickness of the interfacial alloy layer is about 0.2 µm. Amount of residual strain is estimated by comparing the measured phonon frequencies with those predicted from the composition profie, but the shift due to the residual strain is not appreciable. Both the interdiffusion at the interface and the nearly complete relaxation of the lattice mismatch are attributed to the high growth temperature of the CVD sample.

In this paper, a new M-estimation technique for the linear prediction analysis of speech is proposed. Since in the conventional linear prediction (CLP) method the obtained estimates are very much affected by the large amplitude residual parts, in the proposed method we use a loss function which assigns large weighting factor for small amplitude residuals and small weighting factor for large amplitude residuals which is for instance caused by the pitch excitations. The loss function is based on the assumption that the residual signal has an independent and identical t-distribution t(α) with α degrees of freedom. The efficiency of this new estimator depends on α. When α=, we get the CLP method. When the proposed method with small α is applied to the problems of estimating the formant frequencies and bandwidths of the synthetic speech by finding the roots of the prediction polynomial, we can achieve a more accurate and a smaller standard deviation (SD) estimate than that with large α. When the signal is very spiky, the proposed method can ahieve more efficient and accurate estimates than that with robust linear prediction (RBLP) method. The loss function is modified in the similar manner as the autocorrelation method. The solution is calculated by the Newton-Raphson iteration technique. The simulation results show that only few iterations are needed to reach a stationary point, the stationary point is always a local minimum and the obtained prediction filter is always minimum phase. Preliminary experiments on the human speech data indicate that the obtained results are insensitive to the placement of the analysis window and a higher spectral resolution than the CLP and RBLP method can be achieved.

In this letter, it is clarified that the quantum noise properties of the linear amplification and locking amplification in the injection locked laser process are different. The noise property of the locking amplification is newly given.

Thin Si films grown on anodized porous silicon have been characterized using a high-energy ion scattering technique with related simulations of MeV ions in solids. It turned out that the simulations are necessary and very usuful for quantitative and nondestractive analysis of thin films with thicknesses less than 100 nm. In the case of the epitaxial Si films examined, it is often insufficient for the characterization of crystalline quality to measure only the channeling minimum yield, and therefore, it is emphasized that angular scans over the critical angle in the vicinity of a channeling direction must be performed for the analysis of possible imperfections in thin films. The possible imperfections observed in the epitaxial specimen are treated quantitatively.

We report on 1N branching devices for fiber-optic networks. A novel Y-pattern mask for loss reduction in branching waveguide has been investigated based on simulation. 18 branching waveguides fabricated by ion-exchange proved that the scattering loss at the branching region made with novel Y-pattern is reduced considerably. Pigtailing technique has been developed using glass fiber arrays (FAs). The fibers in FA are aligned precisely, so that all fibers can be easily and precisely put into alignment with the output ports in a branching waveguide chip at the same time. A glass plate is used for reinforcement which improves mechanical and thermal stability of the device. Reliability of packaged devices is being strongly demanded. Various reliability tests have been performed with packaged 18 branching devices and those results are presented.

The a-Si films deposited on quartz substrates were crystallized by lateral sweep annealing in steep temperature gradient using a gas burner. Random nucleation in amorphous region was effectively suppressed in the temperature gradient, so lateral solid phase epitaxial growth from crystallites generated at the initial stage of lateral sweep annealing spread over 100 µm. Their crystallographic orientations were mostly (100).

This letter considers a subclass of t-symmetric error correcting/all unidirectional error detecting (t-SyEC/AUED) codes in which the information is represented in an m-out-of-k coded form, which thus can be regarded as virtually systematic for practical purposes. For t3, previous researchers proposed methods for constructing codes of this subclass which are either optimal or of asymptotically optimal order. This letter proposes a new method for constructing, for any values of t, m and k, codes that are either optimal or of asymptotically optimal order. The redundancy of the obtained code is of the order tlog2k bits when mt.

In case of the system identification problem, such as an echo canceller, estimated impulse response obtained by the frequency-domain adaptive filter based on the circular convolution has estimation error because the unknown system is based on the linear convolution in the time domain. In this correspondence, we consider a sufficient condition to reduce the estimation error.

The mechanisms for executing concurrent applications proposed so far fall into one of three groups: processes, kernel-level threads, and user-level threads. Each of them is insufficient in terms of either parallelism, the flexibility to combine separately developed programs at run-time, or costs of operations such as creation, switching, and termination. A thread facility in the XERO operating system overcomes this problem and provides a uniform framework for executing concurrent applications. To achieve parallelism of threads, the flexibility to combine separately developed programs at run-time, and fast thread operations, the operating system kernel and a thread management module in a user address space manage threads cooperatively. We implemented the cooperative thread management mechanism and measured its performance to examine the effectiveness of our approach.

This paper describes the integration of a qualitative method and a quantitative method by Bottleneck Diagnosis/Improvement Expert Systems for Synchronized queueing network (BDES-S and BIES-S). On the basis of qualitative reasoning, BDES-S can carry out parameter tuning in order to diagnose and improve bottlenecks of synchronized queueing networks. BDES-S can produce several alternative qualitative improvement plans for one bottleneck server. BIES-S can produce quantitative improvement equations for each qualitative improvement plan. Our method using BDES-S and BIES-S can integrate both quantitative and qualitative methods for parameter tuning on complicated queueing synchronized networks.

This letter proposes an improvement of the equivalent source method in order to give an accurate solution for the scattering of an electromagnetic plane wave by a conducting cylinder with edges.

This paper describes a new metric for evaluating the cost effectiveness of software reviews. The proposed metric is based on the degree to which costs needed for detecting all faults from software are reduced by software reviews in a project. The metric can be interpreted as combining two conventional metrics proposed by Fagan (1976) and Collofello and Woodfield (1989). As the proposed metric is normalized by virtual testing cost, we can compare the values of it among any different kind of projects. Using an experimental evaluation of the conventional metrics and the proposed metric for data collected in an industrial environment, we show the validity and usefulness of the proposed metric. In addition, we present a method to estimate a value of the proposed metric by using only the values which can be computed during the software reviews.

A specification formalism for business application software is presented. Our approach is to investigate specification documents which are actually used in development projects of business applications in banking, insurance, and government systems. Since the specification documents are prepared mainly for users' review for the developing software, the representation of the documents is designed to be easy to understand for users, only in business terminology without losing a certain level of formality. Also, to avoid redundancy of the specification, there are some implicit assumptions in the specification. We have analyzed some commonality of these assumptions hidden in specification documents and are trying to construct a language by formalizing the underlying system model.

Isotope dilution secondary ion mass spectroscopy (ID-SIMS) using 30Si as a spike is investigated as a quantitative analysis method for trace amounts of Si. For a standard solution of Si, the relateve standard deviation of results using this method is 5% for 0.2 µg Si, and the determination lower limit is 18 ng. Using this method, the amount of Si deposited on the Ge(100) surface by the self-limited adsorption of SiH2Cl2 is determined to be about 1.00.2 monolayer.

A laser/microwave method using two lasers of different wavelengths for carrier excitation is proposed to evaluate Si surfaces. These constitute a He-Ne laser (wavelength=633 nm, penetration depth=3 µm) and a YAG laser (wavelength=1060 nm, penetration depth=500 µm). Using a microwave probe, the amount of excited carriers can be detected. The carrier concentration is mainly dependent on the condition of the surface when carriers are excited by the He-Ne laser, as well as on the condition of the bulk region when carriers are excited by the YAG laser. Microwave intensities detected under the He-Ne and the YAG lasers illumination are referred to as the surface-recombination-velocity-related microwave intensity (SRMI) and the bulk-related microwave intensity (BRMI), respectively. The difference between SRMI and BRMI is called relateve SRMI (R-SRMI), and is closely related to the condition of the surface and surface active region. We evaluate the surfaces of the samples after plasma and wet etching to remove the photoresist layer. And we evaluate the surfaces of the samples after heat or HF treatment which is done to recover the damage introduced by plasma etching. It was found that the R-SRMI method is better suited to surface evaluation than conventional lifetime measurements.

Microcrystalline silicon embedded in silicon oxide has been prepared by means of a wet oxidation of porous silicon (PS) anodically produced from degenerate Si wafers in a HF solution. As the oxidation proceeded, optical absorptions of the PS specimen in the visible light region shifted obviously to the higher energy side. Visible light emission from the oxidized specimen was observed at room temperature with photoexcitation by a He-Cd laser while the as-prepared specimen emitted no visible lights. These results are discussed in relation to the quantum size effect of the microcrystalline silicon confined in the oxide matrix as well as visible emissions from as-prepared specimens produced from non-degenerate Si wafers.

Silicon-on-insulator (SOI) films fabricated by the wafer bonding technique were studies with capacitance-voltage (C-V) and deep-level transient spectroscopy (DLTS) measurements. For our expereiments, two kinds of SOI wafers were prepared. Many voids were present in one sample (void sample), but few voids were in the other sample (no void sample). Before annealing, two DLTS peaks (Ec-0.48 eV and Ec-0.38 eV) were observed in the SOI layer of the void sample. For the no void sample, different two DLTS peaks (Ec-0.16 eV and Ec-0.12 eV) were observed. The trap with an activation energy of 0.48 eV was annealed out after 450 annealing for 24 h. On the other hand, other traps were annealed out after 450 annealing for several hours. During annealing at 450, thermal donors (TDs) were formed simultaneously. In usual CZ silicon, a DLTS peak of TD was observed around 60 K. In the no void sample, however, a TD peak was observed at a temperature lower than 30 K. This TD was annihilated by rapid thermal annealing. This suggests that the TD with a shallower level was formed in the no void sample after annealing at 450.

This paper describes the impact of EDFAs on AM/FM FDM subcarrier multiplexing (SCM) all-fiber video distribution (AFVD) systems. As AM/FM hybrid system using EDFAs which can simultaneously distribute 11 AM-TV channels and 50 FM-TV channels is proposed and discussed. 4-stage amplifier-branch transmission experiments are introduced. The construction and performance of a newly designed 50 channel FM tuner are also presented.

Asynchronous Transfer Mode (ATM) switching system is expected to handle various kinds of media (such as motion video, computer data, and voice), and traffic control becomes essential to satisfy various quality requirements and to maintain efficient utilization of system resources. Priority control is one possible solution for realizing such a traffic control. In priority control, cells from various media are scheduled for transmission with different priority according to the quality class to which they belong. In this paper, we propose a new priority control method in which cells from various media are stored in their own buffer, we call it class buffer, and priority assignments are carried out based on the number of cells in each class buffer and the delay time. The number of cells in each class buffer is maintained using the counter circuit. The delay time of the cell is checked by the timer circuit for cell group, each of which consists of cells arriving during a periodical time interval. For simulation model, we consider three kinds of traffic; video, computer data, and voice, of which quality requirements are quite different. We show performance results in terms of the cell delay and the cell loss probability in our method through simulation.