A (periodic) correlation function is an important measure to evaluate the effectiveness of pseudorandom sequences. In practice, the sequences are required to have the impulse-like autocorrelation function. Also, crosscorrelation magnitudes of the distinct sequences must be as low as possible. Theoretically, the correlation of sequences has a strong connection with problems of algebraic coding and combinatorics. Namely, the correlation distribution of sequences is related to the weight distribution of codewords in algebraic codes. Furthermore, binary sequences with ideal two-level autocorrelation are equivalent to cyclic Hadamard difference sets in combinatorics. Therefore, a good knowledge of coding theory and combinatorics is helpful for a study of sequences with low correlation. In this thesis, the correlation of binary sequences is studied by the aid of fruitful results of coding theory and combinatorics. From this study, some interesting properties are presented on the correlation of binary sequences, and several new binary sequences with low correlation are discovered. The outline of thesis is as follows. First of all, crosscorrelation properties of binary sequences with ideal two-level autocorrelation are studied. The 3- and 5-valued crosscorrelation properties of several classes of binary sequences with ideal two-level autocorrelation are completely determined by either theoretical proofs or conjectures. Second, new binary sequences of period of a multiple of 4 are proposed by making use of the interleaved structure of sequences. The sequences have three-valued out-of-phase autocorrelation, i.e., {0, -4, +4}, which is optimal with respect to autocorrelation magnitude. Third, a new binary sequence family with low correlation and a large family size is proposed and its asymptotic optimality is examined. With respect to maximum correlation, a family size, and a linear complexity, the sequence family is competitive among all known binary sequence families. Finally, the construction of quadratic bent functions of a special polynomial form is presented by providing necessary and sufficient conditions on the coefficients of the polynomial. The resulting quadratic bent functions can be employed for the linear feedback shift register (LFSR) implementation of a family of bent sequences, which is a potential candidate for future code-division multiple access (CDMA) system.

The aim of this thesis work is to investigate the algorithms of speech recognition. The author programmed and simulated the designed systems for algorithms of speech recognition in MATLAB. There are two systems designed in this thesis. One is based on the shape information of the cross-correlation plotting. The other one is to use the Wiener Filter to realize the speech recognition. The simulations of the programmed systems in MATLAB are accomplished by using the microphone to record the speaking words. After running the program in MATLAB, MATLAB will ask people to record the words three times. The first and second recorded words are different words which will be used as the reference signals in the designed systems. The third recorded word is the same word as the one of the first two recorded words. After recording words, the words will become the signals’ information which will be sampled and stored in MATLAB. Then MATLAB should be able to give the judgment that which word is recorded at the third time compared with the first two reference words according to the algorithms programmed in MATLAB. The author invited different people from different countries to test the designed systems. The results of simulations for both designed systems show that the designed systems both work well when the first two reference recordings and the third time recording are recorded from the same person. But the designed systems all have the defects when the first two reference recordings and the third time recording are recorded from the different people. However, if the testing environment is quiet enough and the speaker is the same person for three time recordings, the successful probability of the speech recognition is approach to 100%. Thus, the designed systems actually work well for the basical speech recognition.

A (periodic) correlation function is an important measure to evaluate the effectiveness of pseudorandom sequences. In practice, the sequences are required to have the impulse-like autocorrelation function. Also, crosscorrelation magnitudes of the distinct sequences must be as low as possible. Theoretically, the correlation of sequences has a strong connection with problems of algebraic coding and combinatorics. Namely, the correlation distribution of sequences is related to the weight distribution of codewords in algebraic codes. Furthermore, binary sequences with ideal two-level autocorrelation are equivalent to cyclic Hadamard difference sets in combinatorics. Therefore, a good knowledge of coding theory and combinatorics is helpful for a study of sequences with low correlation. In this thesis, the correlation of binary sequences is studied by the aid of fruitful results of coding theory and combinatorics. From this study, some interesting properties are presented on the correlation of binary sequences, and several new binary sequences with low correlation are discovered. The outline of thesis is as follows. First of all, crosscorrelation properties of binary sequences with ideal two-level autocorrelation are studied. The 3- and 5-valued crosscorrelation properties of several classes of binary sequences with ideal two-level autocorrelation are completely determined by either theoretical proofs or conjectures. Second, new binary sequences of period of a multiple of 4 are proposed by making use of the interleaved structure of sequences. The sequences have three-valued out-of-phase autocorrelation, i.e., {0, -4, +4}, which is optimal with respect to autocorrelation magnitude. Third, a new binary sequence family with low correlation and a large family size is proposed and its asymptotic optimality is examined. With respect to maximum correlation, a family size, and a linear complexity, the sequence family is competitive among all known binary sequence families. Finally, the construction of quadratic bent functions of a special polynomial form is presented by providing necessary and sufficient conditions on the coefficients of the polynomial. The resulting quadratic bent functions can be employed for the linear feedback shift register (LFSR) implementation of a family of bent sequences, which is a potential candidate for future code-division multiple access (CDMA) system.

This thesis has detailed the extensive analysis of the XAS and RIXS spectra of LiFePO4 and FePO4, with the primary focus on LiFePO4. One of the primary motivations for this study was to understand the electronic structure of the two compounds and, in particular, shed some light on the nature of electron correlation within the samples. Two classes of band structure calculations have come to light. One solution uses the Hubbard U parameter, and this solution exhibits a band gap of about 4 eV. Other solutions that use standard DFT electron correlation functionals yield band gaps between 0 and 1.0 eV. <p>The RIXS spectra of LiFePO4 and FePO4 were analyzed using Voigt function fitting, an uncommon practice for RIXS spectra. Each of the spectra was fit to a series of Voigt functions in an attempt to localize the peaks within the spectra. These peaks were determined to be RIXS events, and the energetic centers of these peaks were compared to a small band gap band structure calculation. The results of the RIXS analysis strongly indicate that the small gap solution is correct. This was a surprising result, given that LiFePO4 is an ionic, insulating transition metal oxide, showing all of the usual traits of a Mott-type insulator. <p>This contradiction was explained in terms of polaron formation. Polarons can severely distort the lattice, which changes the local charge density. This changes the local DOS such that the DOS probed by XAS or RIXS experiments is not necessarily in the ground state. In particular, polaron formation can reduce the band gap. Thus, the agreement between the small gap solution and experiment is false, in the sense that the physical assumptions that formed the basis of the small gap calculations do not reflect reality. Polaronic distortion was also tentatively put forward as an explanation for the discrepancy between partial fluorescence yield, total fluorescence yield, and total electron yield measurements of the XAS spectra of LiFePO4 and FePO4.

Inspection of solder joint interconnection has been a crucial process in the electronics manufacturing industry to reduce manufacturing cost, improve yield, and ensure product quality and reliability. New inspection techniques are urgently needed to fill in the gap between available inspection capabilities and industry requirement of low-cost, fast-speed, and highly reliable inspection systems. The laser ultrasound inspection system under development aims to provide a solution that can overcome some of the limitations of current inspection techniques. Specifically, the fully developed system will be an automated system that is capable of inspecting hidden solder joints with multiple defect types. This research work includes the following aspects: 1) Inspection system integration and automation to improve system throughput and capability, system performance characterization by stability study and gage repeatability and reproducibility study , 2) Development and implementation of signal processing methods, including time-domain correlation coefficient analysis, auto-comparison method, and frequency-domain spectral estimation, to allow for fast and accurate interpretation of vibration signals, 3) Development of a finite element modal model followed by experimental validation. The modal analysis results indicate there are unique mode frequencies and mode shapes associated with certain solder joint defects, and 4) Study of the systems unique capability in detecting solder joint fatigue cracks.

Investment of mutual fund has always been popular to the common investor. No matter investing at Systematic Investment Plan or One-time Investment, choosing a ¡§good¡¨ mutual fund is expected for every investor. However, how to find a good one among a large number of funds? In the past reports or theses, there are many reasons of influencing mutual fund performance, which include fund¡¦s size among others. The common sense said that ¡§if you want to invest in mutual fund, you should choose the larger size ¡¨ Is that true? Through the past reports we can find out different opinions. This study mainly research into the relationship between performance and size of domestic open-ended mutual funds. Expect to give a simpler data for reference and lower the risk before general investors put money into funds. The logic of Spearman's Rank Correlation coefficient would be applied as the statistical inference in this study, and the domestic open-ended equity fund, balanced fund, and quasi-money market fund will be used as the observed samples. Monthly performance and size is the observed unit of time in this research period from March 2001 to February 2010. Thus via this mode will know whether the correlation between fund¡¦s performance and size is positive, negative or there is no correlation. The conclusions of this study are presented as follows: 1. There is a low positive correlation between performance and size for equity fund and quasi-money market fund. But the balanced fund does not show any correlation for these two variables. 2. Moreover, the study shows there is better performance for investing in over 4 billion NT asset of equity fund in a short term period. But the result of balanced fund and quasi-money market fund can¡¦t highlight the optimal size in a short term period. 3. From the long term point of view, the optimal interval of size for equity and balanced fund is between 1 billion and 2 billion. And the optimal size to quasi-money market fund is over 40 billion.

This paper presents an analysis of the linkage between Hungary¡¦s and its neighbouring country, Slovakia¡¦s special kind of political-, and economic relations over the past two decades. The author searches for an answer to the question what fundamental factors, internal and international, determine the long-term growth of the two countries¡¦ bilateral trade and the often tensed bilateral interstate relation as well as how the latter influences economic development in the common cross-border areas. Applying the models of mathematical economics, the author carried out an econometric investigation to prove her hypothesis on the bilateral political relation affects bilateral trade.

This thesis presents the research results of a correlation and model based on nano and macroindentation hardness measurements. The materials used to develop and test the correlation include bulk tantalum and O1 tool steel. Following the literature review and a detailed description of the experimental techniques, the results of the nanoindentation hardness measurements are presented. After applying the methods and correlation recommended here, the results should give an accurate value of hardness in the Vickers scale for microstructural features that are too small to be precisely and exclusively measured using the traditional macroindentation hardness technique. The phenomena and influential factors in nanoindentation hardness testing are also discussed. These phenomena and theories are consistent with the microstructural behavior predicted in the Nix and Gao model for mechanism-based strain gradients. Implementing the correlation factors and/or correlation curve, accurate results can be found for metals over a broad hardness range. Initially, this research may impact the pipeline division of the petroleum industry by providing a correlation to the Vickers scale for nanoindentation testing of microstructural features. This thesis may also provide a research methodology to develop hardness correlations for materials other than metals. This thesis consists of eight chapters. Following an introduction in Chapter I, the research motivations and objectives are highlighted in Chapter II. Chapter III explains the multi-scale indentation techniques used in this thesis and Chapter IV presents the materials preparation techniques used. Then, the results are presented in Chapter V, followed by the factors affecting nanoindentation hardness in Chapter VI. Finally, Chapters VII and VIII reveal the indentation contact analysis, correlation, and conclusions of this research, respectively.

Elastography is a non-invasive imaging modality that uses ultrasound to estimate the elasticity of soft tissues. The resulting images are called 'elastograms'. Elastography techniques are promising as cost-effective tools in the early detection of pathological changes in soft tissues. The quality of elastographic images depends on the accuracy of the local displacement estimates. Cross-correlation based displacement estimators are precise and sensitive. However cross-correlation based techniques are computationally intense and may limit the use of elastography as a real-time diagnostic tool. This study investigates the use of parallel general purpose graphics processing unit (GPGPU) engines for speeding up generation of elastograms at real-time frame rates while preserving elastographic image quality. To achieve this goal, a cross-correlation based time-delay estimation algorithm was developed in C programming language and was profiled to locate performance blocks. The hotspots were addressed by employing software pipelining, read-ahead and eliminating redundant computations. The algorithm was then analyzed for parallelization on GPGPU and the stages that would map well to the GPGPU hardware were identified. By employing optimization principles for efficient memory access and efficient execution, a net improvement of 67x with respect to the original optimized C version of the estimator was achieved. For typical diagnostic depths of 3-4cm and elastographic processing parameters, this implementation can yield elastographic frame rates in the order of 50fps. It was also observed that all of the stages in elastography cannot be offloaded to the GPGPU for computation because some stages have sub-optimal memory access patterns. Additionally, data transfer from graphics card memory to system memory can be efficiently overlapped with concurrent CPU execution. Therefore a hybrid model of computation where computational load is optimally distributed between CPU and GPGPU was identified as an optimal approach to adequately tackle the speed-quality problem in real-time imaging. The results of this research suggest that use of GPGPU as a co-processor to CPU may allow generation of elastograms at real time frame rates without significant compromise in image quality, a scenario that could be very favorable in real-time clinical elastography.

Although e-enterprise has been a main stream, there are many stories about the resistance of employees. On the other hand, by the times of knowledge economy age and the popularity of e-learning, a lot of people join the online classes or traditional classes with the support of e-learning system after their office hours. Actually, e-learning system is one kind of e-enterprise systems. If the e-learning experience can let the students be more knowledgeable to the e-enterprise, it will be very helpful to proceed e-enterprise project. The purpose of this research is to probe whether the experience of e-learning would impact the cognition of e-enterprises development. This research adopted quantitative method to explore the relationship between e-learning experience and e-enterprise cognition. A questionnaire survey has been sent to the students who have used the e-learning systems in online courses or traditional courses. According to statistic analyses, the major conclusions are as follows: 1. The e-learning experiences have significant impact on e-enterprise cognition. 2. The impact of the experience of using discussion tools of e-learning systems on e-enterprise cognition will not be interfered by student¡¦s studying attitude. 3. However, The impact of the experience of using supplementary tools of e-learning systems on e-enterprise cognition will be interfered by student¡¦s studying attitude.