Experimental Verification And Theoretical Analysis Of The Relationships Between Hardness, Elastic Modulus, And The Work Of Indentation

The relationship between hardness (H), reduced modulus (E-r), unloading work (W-u), and total work (W-t) of indentation is examined in detail experimentally and theoretically. Experimental study verifies the approximate linear relationship. Theoretical analysis confirms it. Furthermore, the solutions to the conical indentation in elastic-perfectly plastic solid, including elastic work (W-e), H, W-t, and W-u are obtained using Johnson's expanding cavity model and Lame solution. Consequently, it is found that the W-e should be distinguished from W-u, rather than their equivalence as suggested in ISO14577, and (H/E-r)/(W-u/W-t) depends mainly on the conical angle, which are also verified with numerical simulations. (C) 2008 American Institute of Physics.

Numerical verification for instrumented spherical indentation techniques in determining the plastic properties of materials

 Instrumented indentation tests have been widely adopted for elastic modulus determination. Recently, a number of indentation-based methods for plastic properties characterization have been proposed, and rigorous verification is absolutely necessary for their wide application. In view of the advantages of spherical indentation compared with conical indentation in determining plastic proper-ties, this study mainly concerns verification of spherical indentation methods. Five convenient and simple models were selected for this purpose, and numerical experiments for a wide range of materials are carried out to identify their accuracy and sensitivity characteristics. The verification results show that four of these five methods can give relatively accurate and stable results within a certain material domain, which is defined as their validity range and has been summarized for each method.

A discussion about a class of stress intensity factors and its verification

In this paper, new formulae of a class of stress intensity factors for an infinite plane with two collinear semi-infinite cracks are presented. The formulae differ from those gathered in several handbooks used all over the world. Some experiments and finite element calculations have been developed to verify the new formulae and the results have shown its reliability. Finally, the new formulae and the old are listed to show the differences between them.

Verification of a scaling law in few-cycle laser pulses

The scaling law of photoionization in few-cycle laser pulses is verified in this paper. By means of numerical solution of time-dependent Schrodinger equation, the photoionization and the asymmetry degree of photoionization of atoms with different binding potential irradiated by various laser pulses are studied. We find that the effect of increasing pulse intensity is compensated by deepening the atomic binding potential. In order to keep the asymmetric photoionization unchanged, if the central frequency of the pulse is enlarged by k times, the atomic binding potential should also be enlarged by k times, and the laser intensity should be enlarged by k(3) times. (c) 2005 Optical Society of America.

Analytical model of spin filtering effect and its experimental verification in a forward-biased iron-metal-Al2O3-n-type GaAs tunneling structure under optical spin orientation

An analytical model for the spin filtering transport in a ferromagnetic-metal - Al2O3 - n-type semiconductor tunneling structure has been developed, and demonstrated that the ratio of the helicity-modulated photo-response to the chopped one is proportional to the sum of the relative asymmetry in conductance of two opposite spin-polarized tunneling channels and the MCD effect of the ferromagnetic metal film. The performed measurement in an iron-metal/Al2O3/n-type GaAs tunneling structure under the optical spin orientation has verified that all the aspects of the experimental results are very well in accordance with our model in the regime of the spin filtering. After the MCD effect of the iron film is calibrated by an independent measurement, the physical quantity of Delta G(t)/G(t) (Delta G(t) = G(t)(up arrow) - G(t)(down arrow) is the difference of the conductance between two opposite spin tunneling channels, G(t) =( G(t)(up arrow) + G(t)(down arrow))/2 the averaged tunneling conductance), which concerns us most, can be determined quantitatively with a high sensitivity in the framework of our analytical model. Copyright (c) EPLA, 2008.

Study on Closed-set Speaker Identification Based on Biomimetic Pattern Recognition

In this paper, a new classifier of speaker identification has been proposed, which is based on Biomimetic pattern recognition (BPR). Distinguished from traditional speaker recognition methods, such as DWT, HMM, GMM, SVM and so on, the proposed classifier is constructed by some finite sub-space which is reasonable covering of the points in high dimensional space according to distributing characteristic of speech feature points. It has been used in the system of speaker identification. Experiment results show that better effect could be obtained especially with lesser samples. Furthermore, the proposed classifier employs a much simpler modeling structure as compared to the GMM. In addition, the basic idea "cognition" of Biomimetic pattern recognition (BPR) results in no requirement of retraining the old system for enrolling new speakers.

Experimental verification on the origin of plateau-like current-voltage characteristics of resonant tunneling diodes

Current-voltage (I-V) characteristics of GaAs-based resonant tunneling diodes have been investigated in the presence of a perpendicular magnetic field. Electron resonant tunneling is strongly suppressed by the applied magnetic field, leading to peak current decreasing with increasing magnetic field. The observed plateau-like structures appear in negative differential resistance region on the I-V curves and are magnetic-field dependent. The plateau-like structures are due to the coupling between the energy levels in the emitter well and in the main quantum well. (C) 2004 American Institute of Physics.

Application of ICA in on-line verification of the phase difference of the current sensor

The performance of the current sensor in power equipment may become worse affected by the environment. In this paper, based on ICA, we propose a method for on-line verification of the phase difference of the current sensor. However, not all source components are mutually independent in our application. In order to get an exact result, we have proposed a relative likelihood index to choose an optimal result from different runs. The index is based on the maximum likelihood evaluation theory and the independent subspace analysis. The feasibility of our method has been confirmed by experimental results.

Information geometry theory of high-dimension space and application for speaker independent continuous digit speech recognition

In the light of descriptive geometry and notions in set theory, this paper re-defines the basic elements in space such as curve and surface and so on, presents some fundamental notions with respect to the point cover based on the High-dimension space (HDS) point covering theory, finally takes points from mapping part of speech signals to HDS, so as to analyze distribution information of these speech points in HDS, and various geometric covering objects for speech points and their relationship. Besides, this paper also proposes a new algorithm for speaker independent continuous digit speech recognition based on the HDS point dynamic searching theory without end-points detection and segmentation. First from the different digit syllables in real continuous digit speech, we establish the covering area in feature space for continuous speech. During recognition, we make use of the point covering dynamic searching theory in HDS to do recognition, and then get the satisfying recognized results. At last, compared to HMM (Hidden Markov models)-based method, from the development trend of the comparing results, as sample amount increasing, the difference of recognition rate between two methods will decrease slowly, while sample amount approaching to be very large, two recognition rates all close to 100% little by little. As seen from the results, the recognition rate of HDS point covering method is higher than that of in HMM (Hidden Markov models) based method, because, the point covering describes the morphological distribution for speech in HDS, whereas HMM-based method is only a probability distribution, whose accuracy is certainly inferior to point covering.

Study on text-dependent speaker recognition based on Biomimetic Pattern Recognition

We studied the application of Biomimetic Pattern Recognition to speaker recognition. A speaker recognition neural network using network matching degree as criterion is proposed. It has been used in the system of text-dependent speaker recognition. Experimental results show that good effect could be obtained even with lesser samples. Furthermore, the misrecognition caused by untrained speakers occurring in testing could be controlled effectively. In addition, the basic idea "cognition" of Biomimetic Pattern Recognition results in no requirement of retraining the old system for enrolling new speakers.

A speaker-independent continuous speech recognition system using biomimetic pattern recognition

In speaker-independent speech recognition, the disadvantage of the most diffused technology (HMMs, or Hidden Markov models) is not only the need of many more training samples, but also long train time requirement. This paper describes the use of Biomimetic pattern recognition (BPR) in recognizing some mandarin continuous speech in a speaker-independent manner. A speech database was developed for the course of study. The vocabulary of the database consists of 15 Chinese dish's names, the length of each name is 4 Chinese words. Neural networks (NNs) based on Multi-weight neuron (MWN) model are used to train and recognize the speech sounds. The number of MWN was investigated to achieve the optimal performance of the NNs-based BPR. This system, which is based on BPR and can carry out real time recognition reaches a recognition rate of 98.14% for the first option and 99.81% for the first two options to the persons from different provinces of China speaking common Chinese speech. Experiments were also carried on to evaluate Continuous density hidden Markov models (CDHMM), Dynamic time warping (DTW) and BPR for speech recognition. The Experiment results show that BPR outperforms CDHMM and DTW especially in the cases of samples of a finite size.

The design and verification of FPGA CAD toolset

This paper introduces a complete CAD toolset for the implementation of digital logic in a Field-Programmable Gate Array (FPGA) platform. Compared with existing academic toolsets, this toolset introduces formal verification in each step of the tool flow, especially the formal verification of the configuration bitstream. The FPGA CAD tool verification flow using Formality is presented in detail. Using plug-in technology, we have developed an integrated FPGA design kit to incorporate all tools together.

Design and Verification of the Programming Circuit in an Application-Specific FPGA

In this paper we present a methodology and its implementation for the design and verification of programming circuit used in a family of application-specific FPGAs that share a common architecture. Each member of the family is different either in the types of functional blocks contained or in the number of blocks of each type. The parametrized design methodology is presented here to achieve this goal. Even though our focus is on the programming circuitry that provides the interface between the FPGA core circuit and the external programming hardware, the parametrized design method can be generalized to the design of entire chip for all members in the FPGA family. The method presented here covers the generation of the design RTL files and the support files for synthesis, place-and-route layout and simulations. The proposed method is proven to work smoothly within the complete chip design methodology. We will describe the implementation of this method to the design of the programming circuit in details including the design flow from the behavioral-level design to the final layout as well as the verification. Different package options and different programming modes are included in the description of the design. The circuit design implementation is based on SMIC 0.13-micron CMOS technology.

Biomimetic pattern recognition for speaker-independent speech recognition

In speaker-independent speech recognition, the disadvantage of the most diffused technology ( Hidden Markov Models) is not only the need of many more training samples, but also long train time requirement. This paper describes the use of Biomimetic Pattern Recognition (BPR) in recognizing some Mandarin Speech in a speaker-independent manner. The vocabulary of the system consists of 15 Chinese dish's names. Neural networks based on Multi-Weight Neuron (MWN) model are used to train and recognize the speech sounds. Experimental results are presented to show that the system, which can carry out real time recognition of the persons from different provinces speaking common Chinese speech, outperforms HMMs especially in the cases of samples of a finite size.