An automatic question answering system must find, within a corpus,short factual answers to questions posed in natural language. The process involves analyzing the question, retrieving information related to the question, and extracting answers from the retrieved information. This thesis presents a novel approach to answer extraction in an automated question answering (QA) system. The answer extraction approach is an extension of the MultiText QA system. This system employs a question analysis component to examine the question and to produce query terms for the retrieval component which extracts several document fragments from the corpus. The answer extraction component selects a few short answers from these fragments. This thesis describes the design and evaluation of the Redundant Inverse Term Frequency (RITF) answer extraction component. The RITF algorithm locates and evaluates words from the passages that are likely to be associated with the answer. Answers are selected by finding short fragments of text that contain the most likely words based on: the frequency of the words in the corpus, the number of fragments in which the word occurs, the rank of the passages as determined by the IR, the distance of the word from the centre of the fragment, and category information found through question analysis. RITF makes a substantial contribution in overall results, nearly doubling the Mean Reciprocal Rank (MRR), a standard measure for evaluating QA systems.

This thesis develops strain and kinetic energy functions and a finite beam element useful for analyzing curved beams which go through large deflections, such as a hockey stick being swung and bent substantially as it hits the ice. The resulting beam model is demonstrated to be rotation invariant and capable of computing the correct strain energy and reaction forces for a specified deformation. A method is also described by which the model could be used to perform static or dynamic simulations of a beam.

Fiber Bragg gratings (FBGs) are key elements in modern telecommunication and sensing applications. In optical communication, with the advancement of the Erbium doped fiber amplifier (EDFA), there is a great demand for devices with wavelength tunability over the Erbium gain bandwidth (in particular, for wavelength division multiplexing (WDM) networks). The center wavelength of a FBG can be shifted by means of change of temperature, pressure or mechanical axial strain. The axial strain approach is the best method among all other techniques because it allows relatively large wavelength shifts with high speed. Axial strain of up to 4% will be required to cover the whole EDFA region (more than 40 nm of central wavelength shift). The formation of Bragg grating results in significant reduction in mechanical strength of optical fibers especially in tension. As a result, axial strain of only about 1% can be achieved by mechanical stretching of FBGs. In order to achieve the remaining 3% strain compression of FBGs has to be applied. In this thesis, the design and analysis of a novel device for achieving central wavelength shift are presented. In particular, the device has achieved, for a fiber with 12 mm FBG, a shifting of 46 nm in compression and 10.5 nm in tension with a reflection power loss of less than 0.25 dB and a FWHM bandwidth variation of approximately 0.1 nm. Both variations are well below the Bellcore standards requirement of 0.5 dB for peak reflectivity variation and 0.1 nm for bandwidth variation. The device consists of two fixed and one guiding ferrules. The difficulties associated with compressing the FBG were handled by carefully selecting tolerances and adjustment procedures. The device allows both tension and compression of FBGs, and the use of different FBG lengths and actuators. The effects of glue deformation and bending of the FBG during compression were analyzed in detail. Further, using the piezoelectric transducer (PZT) actuator as a driver, tuning speed of around 1.5nm/ms was achieved.

The effects of coupling parameters of active-passive and passive-passive coupling components on the coupling efficiency and signal mixed proportion for polymer optical fiber (POF) communication are investigated. A high sensitivity and easy fabricated POF displacement sensor is proposed by using cycling bending POF. Also, light sources for both Laser diode (LD) and light emitting diode (LED) are employed in this study. Experimental approaches and numerical analysis of rays tracing method and finite element method are performed to investigate the effects of coupling scheme and bent deformation on the optical power attenuation. Experimental results also illustrate the feasibility of using numerical analysis in coupling components and POF displacement sensor design. The effect of V-grooved array¡¦s POF on the coupling efficiency and signal mixed proportion are presented in active-passive components. The results indicate that the effect of the V-groove¡¦s shape and size on the coupling efficiency is very significant for all designed parameters of V-grooved array¡¦s POF. Compared with the parallel V-grooved array, the skew V-grooved array reduces the length of the coupling component and increases the output power between light source and POF. In the Y-branch POF coupler for passive-passive components, both the excess loss and the output power ratio of the Y-branch couplers are very sensitive to the couple angle, the coupling distance and the refractive index of the filling medium between the emitting-end and receiving-end of fibers. The results also show that the proposed model can be used to analyze the coupling efficiencies in the asymmetrical Y-branch or axial symmetrical couplers with acceptable accuracy. In the POF displacement sensor using by cycling bending loss, the results show that the effect of roller¡¦s number, interval and wavelength on light power attenuation is very significant. Based on the experimental data, a linear equation is derived to estimate the relationship between the power loss and the relative displacement. The difference between the estimated results and the experimental results is less than 8%.

The dynamic characteristics of shroud blade group played a significant role in steam turbine design. However, the complex shape and periodical structure of shroud blades make it so hard to find its dynamic characteristics under high speed operation. The complicate shape, periodic structure, and tedious computation limit the application of finite element method in the design analysis of shroud group blades. In order to design the shroud blade group, the component mode synthesis method was employed to derive the system dynamic equation of the grouped periodical blades. For simplicity, a pre-twisted and tapered cantilever beam is used to derive the approximate analytic solution of a rotating turbo blade. Then the approximated eigen solution of single blade is synthesized in company with the constrain condition by using the component mode synthesis method. In order to confirm the feasibility of the proposed simulation method, a real size turbine blade is used to discuss in the study. Through a comparison between the results solved from the proposed method and finite element method of single blade and shroud blade group to prove the reliability of the proposed method. The effect of blade parameters on the dynamic characteristic of shroud blade group has investigated in this work. Numerical results indicate the proposed method is feasible and effective in dynamic design analyses of the shroud blade group.

The Wafer Level Chip Scale Package (WLCSP) is gaining popularity for its performance and ability to meet the miniaturization requirements of portable consumer electronics, such as cell phones. For the industry of electronic package, the package life of electronic products is deemed as the essential consideration in the operation period. In practice, electronic products are usually damaged due to a harsh mechanical impact, such as drop and bending. The solder interconnections provide not only the electronic path between electric components and printing circuit board, but also the mechanical support of components on the printing circuit board, so that the reliability of solder interconnection becomes an essential consideration for a package. In the thesis several parameters, including redistribution layer (RDL) material and thickness, passivation material and thickness, under-bump metallization (UBM) structure factors are discussed. A variety of WLCSP structures are investigated for solder joint reliability performance. In addition to the fatigue lives of the test vehicle, locations and modes of fractured solder joints were observed. It was found that wafer level packaging structure under drop clearly related with the characteristic life. The weakest point of solder ball was intermetallic compound (IMC), and wafer level packaging structure was the crack into the second passivation layer and UBM interface of the corner. WLCSP under temperature cycling test was done and observed the fracture only occurred at the solder ball near the package.

Sandwich beams are composite systems having high stiffness-to-weight and strength-to-weight ratios and are used as light weight load bearing components. The use of thin, strong skin sheets adhered to thicker, lightweight core materials has allowed industry to build strong, stiff, light, and durable structures. Due to the use of viscoelastic polymer constituents, sandwich beams can exhibit time-dependent behavior. This study examines and predicts the time-dependent behavior of sandwich beams driven by the viscoelastic foam core. Governing equations of the deformation of viscoelastic materials are often represented in differential form or hereditary integral form. A single integral constitutive equation is used to model linear viscoelastic materials by means of the Boltzmann superposition principle. Based on the strength of materials approach, the analytical solution for the deformation in a viscoelastic sandwich beam is determined based on the application of the Correspondence Principle and Laplace transform. Finite element (FE) method is used to analyze the overall transient responses of the sandwich systems subject to a concentrated point load at the midspan of the beam. A 2D plane strain element is used to generate meshes of the three-point bending beam. User material (UMAT) subroutine in ABAQUS FE code is utilized to incorporate the viscoelastic constitutive model for the foam core. Analytical models and experimental data available in the literature are used to verify the results obtained from the FE analysis. The stress, strain, and deformation fields during creep responses are analyzed. Parameters such as the viscosity of the foam core, the ratio of the skin and core thicknesses, the ratio of the skin and core moduli, and adhesive layers are varied and their effect on the timedependent behavior of the sandwich system is examined.

Prepainted metal sheets being environment friendly and cost effective as compared to postpainted metal sheets, are widely used in construction, packaging, transportation and automotive industries. One of the key requirements for prepainted coatings is to retain its surface quality and properties during forming process. During forming process, major surface damage occurs when the coated sheet is bent and un-bent around the die corner. To reduce surface damage of coatings, proper control of the parameters during forming and detail study of the surface conditions is required. In the present study, influence of forming parameters such as die radius, lubrication and specimen material are investigated. The influence of these parameters on friction, surface damage and properties of polymer coatings are evaluated. Experiment set-up is built to conduct bending under tension test. This test gives a better way to evaluate coating performance, as it closely simulates the die region of real forming process and considers bending effects. Experimental results show increase in friction and surface damage with decrease in die radius. Moreover, with decrease in die radius hardness of the coating decreases and strain in the specimen increases. Lubrication has some effect on coefficient of friction, but the influence is not as significant as that of die radius. This is attributed to the fact that, the polymer coating itself acts as a solid lubricant in the test. Material effect was studied, polypropylene coating being the softer material compared to PVDF coating shows more surface damage in the form of scratches. Numerical simulations were performed using Finite Element Analysis package (FEA) Abaqus. A 2D model was built, exploiting the plane strain condition for bending under tension test. Numerical simulations indicate that maximum contact pressure and von Mises stress are concentrated at the beginning of the drawing edge. Apart from the location, the value of contact pressure was higher for smaller die radius. Thus, experiments help in studying the effect of forming parameters on coating performance and numerical simulations provide more insight into the critical areas where stresses are high. Numerical simulations also provide a scope to study the effect of material and geometric parameters on performance of coatings without running experiments.

There were three poly-Si TFT made by ELA, SLS, and HREC. The HREC TFT had better reliability than ELA TFT and SLS TFT under AC and hot carrier stress. And the effect of bending in SLS TFT was more obvious then ELA TFT, it provide us a better choose to develop a flexible TFT LCD. In poly-Si TFT, the photon current would decrease if there was a grain boundary in the channel. In all parameters include both manufacture and measurement the HREC TFT had better behaviors than ELA TFT and SLS TFT. But there also some shortcomings we must overcome include we muse growth a heat-retaining layer extra and must etch it and the poly-Si/heat-retaining etch rate and so on.

Aluminum based alloys have wide area of usage in automotive and defense industry and bending processes are frequently applied during production. One of the most important design criteria of bending processes is springback, which can be basically defined as elastic recovery of the part during unloading. To overcome this problem, heat treatment is generally applied to the workpiece material to refine tensile properties. In this study, the effect of heat treatment on springback characteristics of aluminum studied both numerically by using finite element analysis and experimentally. For this purpose, two different materials are selected and various heat treatment procedures are considered. The aluminum sheets having thickness of 1.6 mm, 2 mm and 2.5 mm are bent to 60&amp / #730 / , 90&amp / #730 / and 120&amp / #730 / . The von Mises stress distributions, plastic strain values and punch load values and comparison of the numerical and experimental results are also given.