Дисертації з теми "SHAPE OF TUNNEL"

The ability to collect valuable data concerning the stress, strains, and shape profiles of aircraft and aircraft components during flight is important to fields such as structural health monitoring, gust alleviation, and flutter control. A research interest in the form of a NASA Phase
I SBIR called for possible systems that would be able to take accurate shape sensing data on a flexible wing aircraft. In a joint venture between Luna Technologies Inc. and Virginia
Polytechnic Institute and State University a flexible wing wind tunnel model was designed and constructed as a test article for the Luna Technologies Inc. fiber optic shape sensing system. In order to prove the capability of a fiber optic shape sensing system in a wind tunnel environment a flexible wing test article was constructed. The wing deflections and twists of the test article were modeled using a vortex lattice method called Tornado combined with simple beam theories. The beam theories were linear beam theories and the stiffness of the composite bodies was supplied by static testing of the test articles. The code was iterative in that it ran the VLM code to estimate the forces and moments on the wing and these were applied to a linear beam which gave the wing a new geometry which in turn was run through the VLM. The wind tunnel model was constructed at Virginia Tech using 3-D printing techniques for the fuselage and foam and fiberglass for the wings. On the bottom surface of the wings the Luna Technologies Inc. fiber optic shape sensing fiber was bonded along the leading and tailing edges. The swept-wing test article was experimentally tested in the Virginia Tech 6\'x6\' Stability Wind Tunnel at various airspeeds and the VLM based code results were in agreement, within margins of error and uncertainty, with the experimental results. The agreement of the analytical and experimental results verified the viability of using an iterative VLM code in combination with simple beam theories as a quick and relatively accurate approximation method for preliminary design and testing. The tests also showed that a fiber optic shape sensing system can be sufficiently tested in a wind tunnel environment, and if applied carefully could perhaps in the future provide useful shape and strain measurements.

Master of Science

Orientador: Vicente Lopes Junior
Resumo: A busca por aeronaves capazes de modificar sua geometria melhorando suas características aerodinâmicas incentivou diversos autores a sugerirem modelos de asas adaptativas. Tais modelos utilizam atuadores leves de modo a substituir os atuadores clássicos convencionais sem, no entanto, comprometer a e ciência de voo da aeronave. Dentre os materiais utilizados para isto se destacam as ligas de memória de forma (Ni-Ti), que são capazes de converter energia térmica em energia mecânica e, uma vez deformadas, podem retornar a sua condição original de forma através de seu aquecimento. Neste contexto, o presente trabalho objetiva controlar a posição angular de um aerofólio utilizando para isto um par de os de liga de memória de forma. No modelo de asa proposto, deseja-se estabelecer uma forma para o per l aerodinâmico a partir da determinação de um ângulo entre duas seções da asa. Este ângulo é atingido pelo efeito de memória de forma da liga através da passagem de uma corrente elétrica. A função da corrente elétrica é alterar a temperatura dos atuadores através do efeito Joule, modificando a forma da liga. Devido à presença de efeitos não-lineares, principalmente no modelo matemático da liga, propõe-se a aplicação de controladores não-lineares do tipo liga-desliga.
Doutor

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
A busca por aeronaves capazes de modificar sua geometria melhorando suas características aerodinâmicas incentivou diversos autores a sugerirem modelos de asas adaptativas. Tais modelos utilizam atuadores leves de modo a substituir os atuadores clássicos convencionais sem, no entanto, comprometer a e ciência de voo da aeronave. Dentre os materiais utilizados para isto se destacam as ligas de memória de forma (Ni-Ti), que são capazes de converter energia térmica em energia mecânica e, uma vez deformadas, podem retornar a sua condição original de forma através de seu aquecimento. Neste contexto, o presente trabalho objetiva controlar a posição angular de um aerofólio utilizando para isto um par de os de liga de memória de forma. No modelo de asa proposto, deseja-se estabelecer uma forma para o per l aerodinâmico a partir da determinação de um ângulo entre duas seções da asa. Este ângulo é atingido pelo efeito de memória de forma da liga através da passagem de uma corrente elétrica. A função da corrente elétrica é alterar a temperatura dos atuadores através do efeito Joule, modificando a forma da liga. Devido à presença de efeitos não-lineares, principalmente no modelo matemático da liga, propõe-se a aplicação de controladores não-lineares do tipo liga-desliga.
The search for aircraft capable of modifying its geometry improving its aerodynamic characteristics, encouraged several authors to suggest models of adaptive wings. These models use lightweight actuators to replace conventional classic actuators without, however, compromise aircraft flight efficiency. Shape Memory Alloys (SMA) can be used efficiently for this application. These materials are capable of converting thermal energy into mechanical energy and a deformed time, can return to its original condition so through its heating. The current work aims to control the angular position of an airfoil using a couple of alloy wires of shape memory. In the proposed wing model, it is desired to establish a way for the aerodynamic pro le of the determination of an angle between two sections of the wing. This angle is attained by the alloy shape memory effect by passing an electric current. The function of the electric current is to change the temperature of the actuators through the Joule effect, modifying the shape of the shape memory alloy. Due to the presence of non-linear effects, especially in the mathematical model of the alloy, it proposes the application of nonlinear controllers type on-of

Underground structures perform an important role in transportation systems in many seismically active regions around the world, but empirical data regarding the seismic behavior of these structures is limited. This research works towards filling that empirical gap through the use of scale model shake table testing. Underground seismic soil-structure interaction (USSSI) effects were investigated for a stiff rectangular tunnel cross-section embedded within soft clay. San Francisco Young Bay Mud was used as a prototype soil for developing a scale model soil mixture consisting of kaolinite, bentonite, class C fly ash, and water. A single cell Bay Area Rapid Transit (BART) cut-and-cover subway tunnel was used as the prototype for the 10th scale model subway cross-section. A flexible walled test container originally developed for a pile study at UC Berkeley was modified for use at Cal Poly, San Luis Obispo. The flexible container allows for close approximation of one-dimensional (1D) free-field site response by significantly limiting the rigidity of the boundary conditions and allowing the soil to deform under simple shear. The study was conducted over two shake table testing phases: Phase I consisted of shaking a model soil column to evaluate the ability of the test container to produce adequate 1D free-field site response, and Phase II tests explored the horizontal racking distortion of a shallow rectangular tunnel cross-section subjected to strong transverse ground shaking. Phase I test results and comparison with SHAKE models indicate that the test container can sufficiently mimic 1D free-field conditions, specifically for the primary shear deformation mode. Similarly, the equivalent linear soil-structure interaction code FLUSH was found to adequately model site response for the Phase II soil-structure system. Comparison of recorded horizontal racking distortions of the model structure with those from numerical modeling suggest that current simplified design methods may overestimate distortions to some degree for cases similar to those examined in this research. Overall, the flexible wall testing container shows promise as a viable means for gaining further insight into USSSI topics, as well as various other geotechnical and soil-structure interaction problems.

A supersonic wind tunnel, with a 20" x 20'" test section cross sectional area, was designed and constructed at the Techsburg Wind Tunnel Facility in order to determine the lift and drag on irregularly shaped fragments in supersonic flow. Prior to beginning the wind tunnel design process, a blowdown analysis model was created in order to determine the influence of a number of parameters on tunnel run time and test gas properties throughout the tunnel circuit. The design of the settling chamber, test section, supersonic nozzles, diffuser, and exhaust are presented in this thesis. Diffuser performance has a large influence on wind tunnel efficiency and run time. Therefore, significant efforts should be taken in order to attain the highest possible pressure recovery within the diffuser. The design of wind tunnel components, as well as their stress analysis, was conducted using SolidWorks. The control valve and silencer were sized and selected for the expected tunnel operating conditions. Since the control valve tends to encompass a significant portion of the overall tunnel cost, care must be taken to ensure it has a large enough flow capacity to produce the desired test conditions. Also, attempts must be made to accurately predict the total pressure loss through the silencer, since this loss can have a large impact on the total pressure ratio necessary to produce the design Mach number. Upon completion of the design process, the supersonic wind tunnel was assembled, and shakedown testing was conducted. During shakedown testing it was determined that the wind tunnel was capable of producing Mach 2 flow in the test section. Following shakedown testing, a flow survey was conducted in order to ensure uniform Mach number flow exists throughout the region occupied by the fragments. Based on the flow survey it was determined that within the middle 60% of the test section, the average Mach number was 1.950 and varied by only 0.56% within this region. Two irregularly shaped fragments were tested at Mach 2 flow, over an effective 360° pitch sweep, with wind tunnel runs performed every 10 degrees. Based on the measured force data for both fragments, the lift appeared to follow a sinusoidal curve, with minimum values at 0, 90, and 180° balance pitch angle, and maximum values occurring around 45 and 135° pitch angle. The drag force was observed to follow a gradual curve with minimum values at 0 and 180° balance pitch angle, as expected since the fragment presented area is generally least in this orientation. The maximum drag was found to occur at a balance pitch angle of 90°, once again as expected since the fragment presented area is generally greatest at this angle. It was also observed that the fragment drag tended to be greater for a fragment orientation which places the concave side of the fragment into the direction of the flow.
Master of Science

In the framework of Geotechnical Engineering and Rock Mechanics many cases are known (described in either the classical or the modern tunnelling bibliography) where, even during construction, large deformations and high stresses in the lining are observed. This is the result of natural phenomena identified with swelling and/or squeezing conditions. This thesis is devoted to the study of tunnelling in difficult conditions, with particular attention to the development of large time-dependent deformations. These deformations may develop either during the construction stage, causing instabilities of the tunnel face and unsafe working conditions, or remain hidden during the “short-term”, thus leading to complex problems when the tunnel is put into service. Under these circumstances the construction costs may rise due to the delays in excavation time, the stabilising and heavy support measures to install. Though the physic-chemical reactions which are the basis of these phenomena have been studied for nearly one century, during the last thirty years the research work concentrated on the rigorous identification, quantification and prediction of the models of behaviour associated with them. In particular, during the last few years, two Research Programmes on these topics (“Tunnelling in difficult conditions” and “Mechanised excavation of tunnels”, co-ordinated by Professor Giovanni Barla) were carried out with the financial support of the Italian Ministry for University and Research. Into this contest, a Ph. D. thesis [Barla M., 1999] was dedicated to the determination of the typical stress-paths around a tunnel and the application to laboratory testing by means of a newly developed triaxial cell (Soft Rocks Triaxial Apparatus, SRTA). The samples of a stiff clay came from the Caneva-Stevenà quarry, near Pordenone (Italy), where swelling induced deformations and instabilities caused failure of the 30 cm thick unreinforced concrete lining of the adits. The decision to further investigate these phenomena came from the growing world-wide interest on the subject and from the availability of a new relevant case study. Several cubic samples of tectonized clay shales (Chaotic Complex) were, in fact, obtained at the face of Raticosa tunnel and Osteria access adit, along the new high speed railway line Bologna-Florence. The present study deals with the models of behaviour which were proposed in recent years, with the aim to identify the most significant factors involved in the selection and design of stabilizing measures of the tunnel face and supports to be installed along the heading. The testing programme performed on the clay shales had the task of identifying similarities and/or differences with respect to the previous research. Moreover, the characterisation studies performed allowed for the determination of significant influence of expandable minerals, complex structure and low mechanical properties of these geomaterials. The testing programme included triaxial tests performed on natural material in closely controlled conditions; oedometer type tests were performed on reconstituted samples. The SRTA was modified for the purpose of testing the new material. Other characterization tests (Atterberg limits, X-ray diffraction analyses, oedometer tests on natural material, etc.) were performed in other laboratories (Enel-Hydro, Milan and Seriate). An extended and critical bibliographic study was carried out with the intent of describing the principal available methods for modelling and predicting the swelling behaviour and their consequences. Though several methods are presently available in literature, they are often very specific and effective for particular case studies. Moreover, the models of swelling behaviour are often embedded in relatively simple elastic and elasto-plastic constitutive laws, which do not allow one to take into account time-dependent deformations. Further investigation in the field of advanced models was carried out, with the intent of determining the significant factors influencing the real mechanical behaviour. The second part of this study was devoted to the numerical modelling at the sample scale and at the tunnel scale. Numerical analyses were performed by the Finite Difference Method and an axi-symmetric coupled model reproducing the sample behaviour at laboratory scale. The stress-paths of the triaxial tests reproduced the behaviour of a point located on the tunnel sidewalls during construction with initial isotropic state of stress. Three elasto-plastic laws were assumed for the ground: Drucker-Prager, modified Cam Clay and Nova-Lagioia model [Nova & Lagioia, 2000]. The stress-strain curves obtained from the laboratory tests could be represented in a satisfactory way, but the corresponding excess pore pressure at low stress level (positive) or at incipient failure (negative) could not be predicted reliably. Since any attempt of reproducing the tectonized clay shales behaviour by means of either simple or more complex elasto-plastic models has been shown to be not effective, an alternate way for the purpose of modelling was represented by time-dependent models of visco-elastic plastic type. Considering that the clay shales exhibit at low stress level a significant time-dependent response, the visco-elastic plastic Burgers’ model with Mohr-Coulomb yield criterion (CVISC) as available with the FDM code Flac [Itasca, 1999] was used. The parameters describing the time-dependent response of the specimens (as evidenced during the laboratory tests) were determined by means of closed-from solutions (Burgers’ visco-elastic model) and numerical analyses with the CVISC constitutive equation. In both cases a satisfactory description of the mechanical behaviour could be achieved. Numerical analyses were performed with the intent of reproducing the deformational response of the Raticosa tunnel, for which monitoring data were available (radial and longitudinal displacements). Numerical analyses were performed by the FDM and an axi-symmetric coupled model reproducing the full excavation sequence of an equivalent circular tunnel. The geotechnical parameters entering the CVISC model for the clay shales at the tunnel scale needed to be assessed in terms of the parameters obtained at laboratory scale. In fact, the parameters based on laboratory testing were not likely to reproduce the tunnel behaviour as observed during excavation. This was the case for deformability, strength, and time dependent parameters, which were evaluated on the basis of experience and in situ observations. The tunnel response in terms of plastic zone extension, radial and longitudinal displacements versus time could be reproduced satisfactorily. Based on of the present work, the following conclusions can be drawn: (a) the time-dependent behaviour of the clay shales is a significant factor to be taken under close consideration for the assessment of the tunnel response to excavation (the elasto-plastic constitutive laws are not capable of reproducing the full range of behaviour of the tunnel); (b) laboratory testing is necessary in order to determine the relevant features of the mechanical behaviour of the material, however the parameters determined from laboratory tests cannot be directly used for appropriate prediction of tunnel behaviour; (c) monitoring is essential for the assessment of the tunnel response (stability of the face and of the core ahead of the face), including the effectiveness of the stabilization measures and of the primary lining, and the time of its installation.

A questionnaire survey was conducted in five different villages in Mpumalanga Province. Hundred and fifty traditional healers were interviewed. The aim of the survey was to record and document indigenous knowledge held by the traditional healers on wild ginger and eight other popular plants used by them. The healing properties of wild ginger as perceived by traditional healers, ranged from healing coughs, colds, flu, hysteria, malaria and menstrual disorder, to protection against lightning. Majority (77%) said that there was no difference in medicinal value between cultivated and those grown in the wild. The majority of the traditional healers (72%) said they would appreciate proper training on how to domesticate these plants. Traditional healers do not have professional knowledge and skills to produce theses medicinal plants. Therefore training is crucial to impart these skills. The income category of traditional healers ranged from less than R200 to a maximum of R3000. Traditional healers received as few as 1 to 5 patients per day. The consultation cost ranged from R20 to more than R95. People who gathered plants for traditional healers ranged from 1 to 10 depending on the popularity of the traditional healer and the size of his/ her surgery. An experiment was carried out at Johannesburg Center for the disabled (JOCOD), Lenasia, South of Johannesburg, in a plastic tunnel and under a shade net. The objective of the experiment was to determine the effect of using a tunnel or a shade net on the yield of rhizome and to determine the effect of different harvesting periods on rhizome yield of wild ginger. The treatments were four in number, namely; two growing structures (tunnel and shade net) and two harvesting periods. On the effect of harvesting periods on yield, although there was no significant differences in the number of enlarged roots harvested between the first harvesting period and the second harvesting period, the number of roots tended to be higher during the first harvesting period compared to the second harvesting period. There was a significant difference in the number of rhizomes between the first and the second harvesting periods. On the effect of growth structure on yield of wild ginger, the number of enlarged roots was significantly higher from plants grown in a tunnel compared with those grown in a shade net. There was a significant difference in rhizome circumference between plants grown in a plastic tunnel and those grown in a shade net. There were interactions between the harvesting date and growth structure for fresh enlarged root mass. Fresh mass of enlarged roots of wild ginger was greater during the first harvesting date than during the second harvesting date for plants grown in a plastic tunnel. For small scale or resource poor farmers, herbalists and traditional healers who wish to grow wild ginger under protection, it is better to grow wild ginger in a plastic tunnel than under a shade net, probably because wild ginger performs well in warm conditions. The plastic tunnels have a tendency of maintaining warm temperatures during winter months. Early harvesting of wild ginger at the end of June 28/06 than harvesting in September. This could be because wild ginger grows rapidly throughout the summer season and in winter, the growth rate drops (dormant stage) making early winter the right time to harvest.
Dissertation (M Inst Agrar (Horticulture))--University of Pretoria, 2007.
Plant Production and Soil Science
unrestricted

This study developed a temperature controlled semi-active tuned mass damper (TMD) using shape memory alloy (SMA) for civil structural applications. It addressed the off-tuning issues caused by the variances in structural mass and stiffness when in service, since off-tuning of the TMD increases the structural response. The effect of in-service temperature on SMA can provide adaptive dynamic properties to TMD. Therefore, the natural frequencies can be adjusted to an optimal range. In this thesis, the material characterisation of SMA is studied through acting dynamic cyclic loading. It was found that Cu-Al-Mn SMA has a superior self-centring capacity, adequate fatigue life and a large damping ratio. By controlling the in-service temperature of a cantilever SMA beam, it was found that the stiffness of the SMA increases and the damping ratio reduces with higher temperatures in free vibration. It is important to note that these properties are increasingly sensitive to temperature when pre-stress is applied and the pre-stressed level is approximate to the phase transformation temperature. The potential for employing SMA with temperature control in a semi-active TMD system is considerable. The feasibility of this type of semi-active TMD was studied experimentally by mounting the SMA-based TMD on a cantilever beam to reduce the excessive vibration caused by off-tuning. For lateral loadings, the non-pre-stressed SMA was applied to a steel framed structure for addressing the off-tuning issues experienced under actions caused by earthquakes and wind by conducting shaking table tests. Cooling the SMA can effectively retune the structural frequencies and attenuate the vibration, but heating the SMA contributed limited effectiveness. This is because the damping losses and stiffness variance are relatively small while heating. In simulation studies, a timber floor-TMD system was modelled under vertical excitations. Both heating and cooling of the SMA can effectively retune the structure from its off-tuned state and can consequently reduce the excessive vibration. Moreover, temperature control of the SMA can shift the natural frequencies to avoid resonance under harmonic loadings. Based on the theoretical and experimental studies in this thesis, the temperature controlled semi-active TMD with SMA can address the off-tuning issues experienced by civil structures under various in-service excitations.

Tato diplomová práce uvádí dynamiku klikového mechanismu šestiválcového řadového motoru za účelem návrhu klikového hřídele v CAD programu Pro/Engineer. Následuje popis vibrací klikového mechanismu a analytický výpočet jeho torzních vibrací. Hlavní část diplomové práce se pak zabývá konverzí hřídele do konečno-prvkového modelu v programu ANSYS a jeho importem do prostředí Adams/Engine. V tom je provedena modální analýza klikového ústrojí pro získání vlastních frekvencí a tvarů. Na konec práce je porovnán výstup z analytického řešení a výsledky z multi-body systému.

The thesis is devoted to analysing of flexible buried arch structures. Modelling of the flexible concrete arch is carried out via a nonlinear finite element model that accounts for soil constitutive relations, soil-structure interactions, sequential construction stages and soil compaction. Advanced FE-model was verified by measurement obtained by full-scale field testing of two buried arches. Mathematical optimization methods of genetic algorithms and Levenberg-Marquardt method are applied to already calibrated complex computational models in order to reduce bending and associated flexural stresses in the concrete section of buried arch. Centre line of the arch is parameterized by cubic Bezier curve to reach interpolation of thrust line. Optimization technique is applied with extensive parametrical study which shows the optimal shapes for buried arches of various span/rise ratios, backfill depths and foundation soil types. For practical application are given coordinates of Bézier curve control polygons of particular resulting shape. Subsequently is applied optimization method for a theoretical reduction of tensile stresses obtained by shape optimization of previously verified numerical model of buried arch. Comparisons of earth pressure, bending moment axial force and deflection of flexible structure during sequential construction of different span/raise ratios of buried arches are presented. The behaviour of flexible buried arch with effect of local traffic load model LM1 has been analysed via 3D finite elements model with respect to different depth of backfill above crown.

Due to rapid urbanization, the role of underground construction is increasing day by day. Underground tunnels are used for several purposes such as storage space, transportation, sewage, water and, oil delivery, and so on. Due to the constant pressure of high-rise residential buildings and, traffic movement, tunnels can be damaged. Hence, the study of stability assessment is very imperative. Many researchers have been proven that the stability of a tunnel depends on various factors like cover depth, type of loading, material properties, etc. This paper investigates the stability appraisal of different shapes of the tunnels in rock mass under static load. Finite element software, ANSYS has been used for numerical modeling and investigation of the static response of different shapes of 3-D shallow tunnels, which are Circular, Horse-shoe, Box Shape, and Semi-ellipse considering the same cross sectional area under static loading conditions. In the paper, a load has been applied as pressure through a steel patch on top of the tunnel. A 3-D finite element model has been taken for the numerical study with a constant C/D ratio. This paper aims to compute longitudinal deformation on the lining and crown of each tunnel. The failure of the tunnel along the tunnel axis has been investigated. The conclusion of the study represents that the most stable shape is circular from a deformation point of view among all the tunnels when subjected to static loading conditions.

碩士
國立清華大學
工程與系統科學系
102
The market demand for portable electric equipment increase dramatically year by year. Although transistors develop toward low cost and high density, maintaining device characteristics becomes difficult due to the device fabrication and physics limitations of the device. Designing a device that different from conventional MOSFET is a necessary way. This thesis based on P-I-N structure tunnel field effect transistor which operated by quantum tunneling mechanism. Thus, compared with conventional MOSFET operated by drift mechanism, the Tunneling Transistor can achieve fast on/off characteristic and the OFF current can be decrease. This work is the first time to demonstrate the asymmetric gate tunnel FET. The device is based on SOI wafer. We design the gate structure above nanowire and planar to form asymmetric gate structure. The asymmetric gate structure has different control ability to channel. There is tri-gate structure on source and channel intrinsic junction and the control ability is good. It makes the screening length shorter and leads ION increase. There is planar structure on drain and channel intrinsic junction and the control ability is bad. It makes the screening length longer and leads IOFF smaller than tri-gate tunnel FET. The asymmetric gate tunnel FET has the SSmin 152mV/dec and SSavg 233mV/dec. ION gets to 7×10-7A and IOFF gets to 1×10-15A. The ON/OFF ration is 7×108. Compare to tri-gate tunnel FET and planar tunnel FET, the AG-TFET has the better electric characteristic. We also study in the reliability of AG-TFET. In positive bias stress and hot carrier stress analysis, the degradation behaviors after stress are investigated. The AG-TFET presents better reliability than tri-gate TFET after stress. The lesser degradation is due to the peaks of vertical electric field of AG-TFET is lower than tri-gate structure device. This work shows experimental data for device’s reliability; all the data can display asymmetric gate tunnel field effect transistor has applied to high value actually; it would become the next-generation device.

碩士
國立臺灣科技大學
營建工程系
106
In this study, UDEC software is used to investigate the effects of stress and deformation of horseshoe shape tunnel on unjointed, single joints and two orthogonal jointed rock masses. Whether the rock mass is plastically damaged and the safety factor is calculated to evaluate the safety of the rock mass. First, the horseshoe shape tunnel excavation was carried out on four different overburden depths (K=1) and four different initial stresses (K=0.5, 1, 2, 3). Next, discussing the case where the variation of joint dip angle is for a single joint through the right angle shale disk (K=1), and the two orthogonal jointed rock mass are at four different initial stresses. Finally, compare with orthogonal jointed rock mass with no joints and a single section. The results of this study show that when a single joint passes through the corner, the joint angle between β=15~75˚ the axial stress is large and the plastic zone is produced. The distribution of stress, displacement and plastic zone of two orthogonal jointed rock masses is roughly the superposition of the single joint β=45 ̊ and 135 ̊ trends. Within the scope of the analysis of this study, the most plastic failure was caused by two joint distributions and K=3.

碩士
朝陽科技大學
營建工程系碩士班
96
A comparison study was conducted in this research to investigate the difference in tunneling engineering between gravel tunnel and alternative gravel/shale tunnel using two major highway and railroad tunnels in central Taiwan . The excavation procedure, control/monitoring, and geological investigation data were collected and studied to investigate the major factors affecting the effectiveness of tunnel excavation procedure and construction management for the selected tunnels. As a result of the study, conclusions were drawn to provide suggestions for future better tunneling engineering in similar geological conditions in central Taiwan . The results of the study were summarized as the following: (1) Although shale exhibits better water-sealing characteristics, the seepage flow channels formed within the shale layer may jeopardize the stability of the tunnel excavation. Effective dewatering/drainage systems before and during excavation are necessary for both tunnels in the study to maintain adequate stability for the subsequent construction activities throughout the tunnel excavation process. (2)The use of ground supports such as pipe-curtain technique, or jet grouting is necessary for gravel tunnel, especially in the opening section, when the depth of the over-burden is smaller than 2-3 time of the excavation width. (3) The wet shot-crete can be used for the lining to achieve significant greater effectiveness for gravel tunnel than that by the traditional dry shot-crete. (4) The scheduling management using full capacity rotation resulted in much less idle time in tunneling process than using the traditional rotation as employed in the alternative shale/gravel tunnel.

碩士
國立臺灣大學
土木工程學研究所
102
Taiwan is a mountainous country. Some gravel layers are located in western Taiwan mountain foot and Huatung Valley. Wuho Tableland is a Quaternary Period fluvial fan and risen by Central Range Fault. In this tableland, it still reserved the indication of fluvial fan that we can found, such as the spread of the gravel layers and gravel arrangement. And in the fluvial fan, the grain size and thickness of gravel layers are not equal, so that the stratum would be anisotropic and inhomogeneous. This stratum would affect the availability of geoengineering. Aug 28, 2012, Typhoon Tembin stroke Taiwan with heavy rain, especially for eastern Taiwan that causes sinkhole. The sinkhole is 10 meters in depth. From bore log and geologic investigation, we found the sinkhole is located in Wuho conglomerate. And we want to draw the connection between the configuration of the strata and the sinkhole. In this research, we analyzed into two aspects: experimental method and numerical simulation. Then, we set up sand-box experiment and verify with discrete element method (DEM). Finally, apply proper thickness, depth of gravel layer and depth of tunnel into this case. The results showed that with deeper tunnel comes shallower and wider sinkhole. And thicker gravel layers comes larger shift of sinkhole. This can be seen from both experiments and DEM simulation.

碩士
國立高雄第一科技大學
營建工程所
93
The numerical method of Discontinuous Deformation Analysis (DDA) is adopted in this research. Its theory was originally developed by Dr. Gen-hua Shi and published in 1989. The DDA method is capable of completing the direct deformation and stress analysis in the jointed rock masses and simulating the joint behavior of the rocks under excavations due to allowing the separation, compression, rotation and collision between the DDA blocks. This research employs the newly developed DDA program DDA-2005. The program includes the simulation of the viscous damping in blocks in order to avoid the reflection of the contact energy between the blocks and boundary blocks back to the area of the analysis when the number of the time step is increased to a certain large amount. The energy basically would cause the larger stresses in the simulation than the ones in the field. Although the rock bolts are stalled in the simulation, the simulation result still shows that the rocks around the excavated tunnel would collapse. It is not a comparable result with the field situation. This research adopted the profile of the Ping-Lin three-hole tunnel in Pei-I Highway in order to investigate the influence of the various tunnel profiles to the stress distribution around the excavated area and the newly developed function of the viscous layer. The analysis result shows that the viscous damping layer at the boundary is able to absorb the reflecting energy to the area of the analysis therefore the more realistic simulation of the tunnel excavation using the DDA method could be obtained.

碩士
國立臺灣海洋大學
河海工程學系
102
This experimental study was to explore the dispersion characteristics of air pollution plume over two consecutive triangle hills in the suburban region. The experiments were conducted in the Environmental Wind Tunnel of National Taiwan Ocean University which had a test section with cross section of 2m by 1.4m and 12.6m long. Spires and roughness elements were deployed to simulate the adiabatic atmospheric boundary layer in the suburban region. Methane was used as the tracer for dispersion of air pollution plume. Effects of the angle of triangle hill, source height, and distance between source and the hill on the dispersion characteristics of pollution plume are investigated in the present study.

The unique features of shape memory alloys (SMA) gives them an unmatched ability to be implemented in several fields of engineering. Considering their phase shift capacity, when thermoelectrically driven, SMAs assume an elastic modulus variation predicated upon two key parameters - stress and temperature. Based on the above statement, the present dissertation aims to develop a new vibration control system, which makes use of SMAs in order to extend and improve its operational domain. Initially, an experimental campaign is developed in order to design a mapping of the elastic modulus of a FLEXINOL R SMA sample.This mapping seeks to explore and an optimize the inclusion of shape memory alloys in vibration control systems. In a second step, two types of ATMDs (Suppressor and TMD) are mathematically studied in order to comprise the insertion of a SMA element in the control system. Considering the main purpose of this thesis, a particular case study structure was chosen to carry out the implementation of the new vibration control system. The selected structure consists in a footbridge built over an important highway located in the Lisbon city center, Portugal. At this stage, both the design of the SMA element and the subsequent operational limits are presented. Afterwards, a numerical model computed in MATLAB (The Mathworks, 2014) is developed to simulate the behavior of a two degrees of freedom (TDOF) system. This one provides the system’s behavior (structure + ATMD) towards a predefined harmonic request, evaluating the effects of the implementation of the new vibration control system. Using the above mentioned numerical model, an influence analysis of both control systems was carried out. Several comparisons between the variants of each ATMD (Suppressor and TMD) where drawn, showing the positive and negative aspects of their action. In the end, a single numerical model, with the ability to excite the structure, read its behavior, identify the vibration frequencies and properly tune the control system in real time, performed a complete structural analysis. Finally, a concluding chapter is presented, where the obtained results are discussed. This chapter also mentions the main future development prospects, that may be considered in studies conducted by other researchers.

博士
國立交通大學
電子研究所
105
In this dissertation, we have investigated the process technologies and device characteristics for sub-10nm MOSFET applications. A feasible pathway to scale Ge NWFETs beyond the 10 nm node was proposed by using a novel diamond-shaped Ge and Ge0.9Si0.1 gate-all-around nanowire (NW) FETs with four {111} facets. In-situ ALD O3 treated Ge surface has been demonstrated to improve the interface of Ge FinFETs by removing damages and roughness induced by fin dry etching. Using microwave annealing (MWA) for S/D dopant activation with low thermal budget suppressed the increase of the interface states. The advantages of MWA for dopant activation include low defect density compared to RTA, negligible dopant diffusion, and suppression of non-ideal straggle effect of ion implantation. The tunable diamond-shaped Ge NW was obtained through simple top-down dry etching and blanket Ge epitaxy techniques readily available in mass production. The different etching selectivity of surface orientations for Cl2 and HBr was employed for the three-step isotropic/anisotropic/ isotropic dry etching. The ratio of Cl2 and HBr, mask width, and Ge recess depth were crucial for forming the nearly defect-free suspended Ge channel through effective removal of dislocations near the Si/Ge interface. The fabricated Ge NWs possesses four {111} facets along the <110> direction. This technique could also be applied for forming diamond-shaped Ge0.9Si0.1 and Si NWs. The diamond-shaped Ge and Ge0.9Si0.1 gate-all-around (GAA) NWFETs with four {111} facets were then fabricated. Taking advantages of the GAA configuration, favorable carrier mobility of the {111} surface, nearly defect-free suspended channel, and improved dopant activation by incorporating Si, nFET and pFET with excellent performance have been demonstrated, including an Ion/Ioff ratio exceeding 108, the highest ever reported for Ge-based pFETs. The in-situ atomic layer deposition (ALD) ozone treated Ge surface and MWA have been combined to reduce interface damage and to scale EOT of Ge FinFETs. An atomically thin GeO2 interfacial layer of 0.36 nm is achieved. The superior subthreshold characteristics of 67.8 mV/dec. and 72.9 mV/dec. for Ge n- and p-FinFETs, respectively, were simultaneously obtained for the first time because of the surface smoothing effect of ALD ozone treatment, the interface trap density reduction and diffusionless dopant activation induced by MWA. Furthermore, the gate-induced drain leakage (GIDL) current can be effectively suppressed by using the MWA for the S/D dopant activation. MWA activates dopants through solid-phase epitaxial regrowth with low thermal budget. Optimizing the microwave power during MWA is capable of realizing low defect density at the junction, suppressing dopant diffusion, and mitigating the straggle effect of ion implantation. These favorable features of MWA facilitate the formation of extremely abrupt junction profiles in tunnel field-effect transistors (TFETs). In conjunction with the improved gate-to-channel controllability of the multiple-gate (MG) structure, we demonstrate high-performance lateral n-type and p-type Si-TFETs by using a CMOS-compatible process flow with excellent band-to-band tunneling efficiency and device scalability. The 32-nm MG Si-TFET shows promising characteristics, including a high ON-state current of 41.3 μA/μm, a large current ON/OFF ratio of > 5x107, and minimal short-channel effect by using VG =2 V and VD =1 V.

碩士
國立高雄科技大學
環境與安全衛生工程系
107
With the demand for economic activities and the development of engineering technology, the vehicle tunnels in the metropolitan area gradually appear irregular shapes to bypass natural or man-made obstacles. U-shaped tunnels are common tunnel types. The characteristics of these tunnels are that the length is not necessarily long, but the slope of the entrance is steep because the entrance to the driveway reaches a certain depth in the extremely short hinterland. This type of tunnel includes cross-river tunnels, cross-lake tunnels, cross-harbour tunnels and special tunnels in urban areas. Due to the large number of vehicles and passers-by, evacuation and disaster relief activities will face extremely severe conditions when fires occur in this type of tunnels. Current research rarely discusses the relationship between U-shaped tunnel entrance slope and fire hazard. This study has analyzed the effects of different entrance slopes on both sides of the tunnel and the push-pull phenomenon due to the stack effect. The research method is to use the numerical simulation and model experiments to verify. The conditions of the U-shaped tunnel in the event of a fire are analyzed by FDS. Schlieren photography technique is used to record the variation of the heat flow in the glass tunnel models when various slopes are at the ends of the structure. The stack effect are clearly demonstrated to affect the hot flow and smoke in the model tunnels. The hazards of fires in U-shaped tunnels and the effects of personnel evacuation have been discussed in this study through numerical simulations and model experiments. The results are very helpful in enhancing the fire safety of U-shaped tunnels. Keywords: U-shaped tunnel, vehicle tunnel fire, stack effect, push-pull effect, Fire Dynamics Simulator (FDS), Schlieren photography technique

Hypersonic vehicles are exposed to severe heating loads during their flight in the atmosphere. In order to minimize the heating problem, a variety of cooling techniques are presently available for hypersonic blunt bodies. Introduction of a forward-facing cavity in the nose tip of a blunt body configuration of hypersonic vehicle is one of the most simple and attractive methods of reducing the convective heating rates on such a vehicle. In addition to aerodynamic heating, the overall drag force experienced by vehicles flying at hypersonic speeds is predominate due to formation of strong shock waves in the flow. Hence, the effective management of heat transfer rate and aerodynamic drag is a primary element to the success of any hypersonic vehicle design. So, precise information on both aerodynamic forces and heat transfer rates are essential in deciding the performance of the vehicle. In order to address the issue of both forces and heat transfer rates, right kind of measurement techniques must be incorporated in the ground-based testing facilities for such type of body configurations. Impulse facilities are the only devices that can simulate high altitude flight conditions. Uncertainties in test flow conditions of impulse facilities are some of the critical issues that essentially affect the final experimental results. Hence, more reliable and carefully designed experimental techniques/methodologies are needed in impulse facilities for generating experimental data, especially at hypersonic Mach numbers. In view of the above, an experimental program has been initiated to develop novel techniques of measuring both the aerodynamic forces and surface heat transfer rates. In the present investigation, both aerodynamic forces and surface heat transfer rates are measured over the test models at hypersonic Mach numbers in IISc hypersonic shock tunnel HST-2, having an effective test time of 800 s. The aerodynamic coefficients are measured with a miniature type accelerometer based balance system where as platinum thin film sensors are used to measure the convective heat transfer rates over the surface of the test model. An internally mountable accelerometer based balance system (three and six-component) is used for the measurement of aerodynamic forces and moment coefficients acting on the different test models (i.e., blunt cone with after body, blunt cone with after body and frustum, blunt cone with after body-frustum-triangular fins and sharp cone with after body-frustum-triangular fins), flying at free stream Mach numbers of 5.75 and 8 in hypersonic shock tunnel. The main principle of this design is that the model along with the internally mounted accelerometer balance system are supported by rubber bushes and there-by ensuring unrestrained free floating conditions of the model in the test section during the flow duration. In order to get a better performance from the accelerometer balance system, the location of accelerometers plays a vital role during the initial design of the balance. Hence, axi-symmetric finite element modeling (FEM) of the integrated model-balance system for the missile shaped model has been carried out at 0° angle of attack in a flow Mach number of 8. The drag force of a model was determined using commercial package of MSC/NASTRAN and MSC/PATRAN. For test flow duration of 800 s, the neoprene type rubber with Young’s modulus of 3 MPa and material combinations (aluminum and stainless steel material used as the model and balance) were chosen. The simulated drag acceleration (finite element) from the drag accelerometer is compared with recorded acceleration-time history from the accelerometer during the shock tunnel testing. The agreement between the acceleration-time history from finite-element simulation and measured response from the accelerometer is very good within the test flow domain. In order to verify the performance of the balance, tests were carried out on similar standard AGARD model configurations (blunt cone with cylinder and blunt cone with cylinder-frustum) and the results indicated that the measured values match very well with the AGARD model data and theoretically estimated values. Modified Newtonian theory is used to calculate the aerodynamic force coefficient analytically for various angles of attack. Convective surface heat transfer rate measurements are carried out by using vacuum sputtered platinum thin film sensors deposited on ceramic substrate (Macor) inserts which in turn are embedded on the metallic missile shaped body. Investigations are carried out on a model with and without fin configurations in HST-2 at flow Mach number of 5.75 and 8 with a stagnation enthalpy of 2 MJ/kg for zero degree angle of attack. The measured heating rates for the missile shaped body (i.e., with fin configuration) are lower than the predicted stagnation heating rates (Fay-Riddell expression) and the maximum difference is about 8%. These differences may be due to the theoretical values of velocity gradient used in the empirical relation. The experimentally measured values are expressed in terms of normalized heat transfer rates, Stanton numbers and correlated Stanton numbers, compared with the numerically estimated results. From the results, it is inferred that the location of maximum heating occurs at stagnation point which corresponds to zero velocity gradient. The heat-transfer ratio (q1/Qo)remains same in the stagnation zone of the model when the Mach number is increased from 5.75 to 8. At the corners of the blunt cone, the heat transfer rate doesn’t increase (or) fluctuate and the effects are negligible at two different Mach numbers (5.75 and 8). On the basis of equivalent total enthalpy, the heat-transfer rate with fin configuration (i.e., at junction of cylinder and fins) is slightly higher than that of the missile model without fin. Attempts have also been made to evaluate the feasibility of using forward facing cavity as probable technique to reduce the heat transfer rate and to study its effect on aerodynamic coefficients on a 41° apex angle missile shaped body, in hypersonic shock tunnel at a free stream Mach number of 8. The forward-facing circular cavities with two different diameters of 6 and 12 mm are chosen for the present investigations. Experiments are carried out at zero degree angle of attack for heat transfer measurements. About 10-25 % reduction in heat transfer rates is observed with cavity at gauge locations close to stagnation region, whereas the reduction in surface heat transfer rate is between 10-15 % for all other gauge locations (which is slightly downstream of the cavity) compared with the model without cavity. In order to understand the influence of forward facing cavities on force coefficients, measurement of aerodynamic forces and moment coefficients are also carried out on a missile shaped body at angles of attack. The same six component balance is also being used for subsequent investigation of force measurement on a missile shaped body with forward facing cavity. Overall drag reductions of up to 5 % is obtained for a cavity of 6 mm diameter, where as, for the 12 mm cavity an increase in aerodynamic drag is observed (up to about 10%). The addition of cavity resulted in a slight increase in the missile L/D ratio and did not significantly affect the missile lateral components. In summary, the designed balances are found to be suitable for force measurements on different test models in flows of duration less than a millisecond. In order to compliment the experimental results, axi-symmetric, Navier-Stokes CFD computations for the above-defined models are carried out for various angles of attack using a commercial package CFX-Ansys 5.7. The experimental free stream conditions obtained from the shock tunnel are used for the boundary conditions in the CFD simulation. The fundamental aerodynamic coefficients and heat transfer rates of experimental results are shown to be in good agreement with the predicted CFD. In order to have a feeling of the shock structure over test models, flow visualization experiments have been carried out by using the Schlieren technique at flow Mach numbers of 5.75 and 8. The visualized shock wave pattern around the test model consists of a strong bow shock which is spherical in shape and symmetrical over the forebody of the cone. Experimentally measured shock stand-off distance compare well with the computed value as well as the theoretically estimated value using Van Dyke’s theory. These flow visualization experiments have given a factual proof to the quality of flow in the tunnel test section.

Hypersonic vehicles are exposed to severe heating loads during their flight in the atmosphere. In order to minimize the heating problem, a variety of cooling techniques are presently available for hypersonic blunt bodies. Introduction of a forward-facing cavity in the nose tip of a blunt body configuration of hypersonic vehicle is one of the most simple and attractive methods of reducing the convective heating rates on such a vehicle. In addition to aerodynamic heating, the overall drag force experienced by vehicles flying at hypersonic speeds is predominate due to formation of strong shock waves in the flow. Hence, the effective management of heat transfer rate and aerodynamic drag is a primary element to the success of any hypersonic vehicle design. So, precise information on both aerodynamic forces and heat transfer rates are essential in deciding the performance of the vehicle. In order to address the issue of both forces and heat transfer rates, right kind of measurement techniques must be incorporated in the ground-based testing facilities for such type of body configurations. Impulse facilities are the only devices that can simulate high altitude flight conditions. Uncertainties in test flow conditions of impulse facilities are some of the critical issues that essentially affect the final experimental results. Hence, more reliable and carefully designed experimental techniques/methodologies are needed in impulse facilities for generating experimental data, especially at hypersonic Mach numbers. In view of the above, an experimental program has been initiated to develop novel techniques of measuring both the aerodynamic forces and surface heat transfer rates. In the present investigation, both aerodynamic forces and surface heat transfer rates are measured over the test models at hypersonic Mach numbers in IISc hypersonic shock tunnel HST-2, having an effective test time of 800 s. The aerodynamic coefficients are measured with a miniature type accelerometer based balance system where as platinum thin film sensors are used to measure the convective heat transfer rates over the surface of the test model. An internally mountable accelerometer based balance system (three and six-component) is used for the measurement of aerodynamic forces and moment coefficients acting on the different test models (i.e., blunt cone with after body, blunt cone with after body and frustum, blunt cone with after body-frustum-triangular fins and sharp cone with after body-frustum-triangular fins), flying at free stream Mach numbers of 5.75 and 8 in hypersonic shock tunnel. The main principle of this design is that the model along with the internally mounted accelerometer balance system are supported by rubber bushes and there-by ensuring unrestrained free floating conditions of the model in the test section during the flow duration. In order to get a better performance from the accelerometer balance system, the location of accelerometers plays a vital role during the initial design of the balance. Hence, axi-symmetric finite element modeling (FEM) of the integrated model-balance system for the missile shaped model has been carried out at 0° angle of attack in a flow Mach number of 8. The drag force of a model was determined using commercial package of MSC/NASTRAN and MSC/PATRAN. For test flow duration of 800 s, the neoprene type rubber with Young’s modulus of 3 MPa and material combinations (aluminum and stainless steel material used as the model and balance) were chosen. The simulated drag acceleration (finite element) from the drag accelerometer is compared with recorded acceleration-time history from the accelerometer during the shock tunnel testing. The agreement between the acceleration-time history from finite-element simulation and measured response from the accelerometer is very good within the test flow domain. In order to verify the performance of the balance, tests were carried out on similar standard AGARD model configurations (blunt cone with cylinder and blunt cone with cylinder-frustum) and the results indicated that the measured values match very well with the AGARD model data and theoretically estimated values. Modified Newtonian theory is used to calculate the aerodynamic force coefficient analytically for various angles of attack. Convective surface heat transfer rate measurements are carried out by using vacuum sputtered platinum thin film sensors deposited on ceramic substrate (Macor) inserts which in turn are embedded on the metallic missile shaped body. Investigations are carried out on a model with and without fin configurations in HST-2 at flow Mach number of 5.75 and 8 with a stagnation enthalpy of 2 MJ/kg for zero degree angle of attack. The measured heating rates for the missile shaped body (i.e., with fin configuration) are lower than the predicted stagnation heating rates (Fay-Riddell expression) and the maximum difference is about 8%. These differences may be due to the theoretical values of velocity gradient used in the empirical relation. The experimentally measured values are expressed in terms of normalized heat transfer rates, Stanton numbers and correlated Stanton numbers, compared with the numerically estimated results. From the results, it is inferred that the location of maximum heating occurs at stagnation point which corresponds to zero velocity gradient. The heat-transfer ratio (q1/Qo)remains same in the stagnation zone of the model when the Mach number is increased from 5.75 to 8. At the corners of the blunt cone, the heat transfer rate doesn’t increase (or) fluctuate and the effects are negligible at two different Mach numbers (5.75 and 8). On the basis of equivalent total enthalpy, the heat-transfer rate with fin configuration (i.e., at junction of cylinder and fins) is slightly higher than that of the missile model without fin. Attempts have also been made to evaluate the feasibility of using forward facing cavity as probable technique to reduce the heat transfer rate and to study its effect on aerodynamic coefficients on a 41° apex angle missile shaped body, in hypersonic shock tunnel at a free stream Mach number of 8. The forward-facing circular cavities with two different diameters of 6 and 12 mm are chosen for the present investigations. Experiments are carried out at zero degree angle of attack for heat transfer measurements. About 10-25 % reduction in heat transfer rates is observed with cavity at gauge locations close to stagnation region, whereas the reduction in surface heat transfer rate is between 10-15 % for all other gauge locations (which is slightly downstream of the cavity) compared with the model without cavity. In order to understand the influence of forward facing cavities on force coefficients, measurement of aerodynamic forces and moment coefficients are also carried out on a missile shaped body at angles of attack. The same six component balance is also being used for subsequent investigation of force measurement on a missile shaped body with forward facing cavity. Overall drag reductions of up to 5 % is obtained for a cavity of 6 mm diameter, where as, for the 12 mm cavity an increase in aerodynamic drag is observed (up to about 10%). The addition of cavity resulted in a slight increase in the missile L/D ratio and did not significantly affect the missile lateral components. In summary, the designed balances are found to be suitable for force measurements on different test models in flows of duration less than a millisecond. In order to compliment the experimental results, axi-symmetric, Navier-Stokes CFD computations for the above-defined models are carried out for various angles of attack using a commercial package CFX-Ansys 5.7. The experimental free stream conditions obtained from the shock tunnel are used for the boundary conditions in the CFD simulation. The fundamental aerodynamic coefficients and heat transfer rates of experimental results are shown to be in good agreement with the predicted CFD. In order to have a feeling of the shock structure over test models, flow visualization experiments have been carried out by using the Schlieren technique at flow Mach numbers of 5.75 and 8. The visualized shock wave pattern around the test model consists of a strong bow shock which is spherical in shape and symmetrical over the forebody of the cone. Experimentally measured shock stand-off distance compare well with the computed value as well as the theoretically estimated value using Van Dyke’s theory. These flow visualization experiments have given a factual proof to the quality of flow in the tunnel test section.

碩士
淡江大學
土木工程學系碩士班
93
As earthquakes had brought terrible losses all over the world in every year, the use of control devices to improve dynamic characteristic of civil structures has become widely accepted in civil engineering. In this research, an hybrid tuned mass damper (HTMD) was constructed and equipped at the top floor of the scaled model of a 3-story frame building to verify its applicability using the shaking table in the department of Civil Engineering, Tamkang University. Firstly, a mathematical model called full-order-system was identified to simulate the dynamic behavior of the 3-story model equipped with an HTMD under the excitations of the actuator command and shaking table. In this system, the possible control-structure interaction induced by the actuator has been taken into account. Through the balanced-state reduction and the choice of the appropriate physical quantities for feedback, the LQG (Linear Quadratic Gaussian) control law was used to design the controllers. For implementation, the discrete dynamic output feedback equation was formed and directly used for calculating the controller command in real time. The control purpose is to reduce the adjacent drifts between floors and the absolute acceleration of building floors. The LQG controllers designed were implemented on the 3-story building equipped with an HTMD by conducting shake table tests. The time scaling factor was considered in the tests. A passive tuned mass damper (TMD), which is corresponding to HTMD with no control command, and another type of active devices – active mass driver (AMD) were both installed on the same building model for the comparisons of their control effectiveness. In designing the controllers for the building with an AMD, the LQG strategy following the same procedures as in the HTMD case was employed. From the time domain and frequency domain analyses of the experimental results, we found that the HTMD has a remarkable effect on reducing the response if the weightings were appropriately adjusted. It is also shown that the application of LQG strategy to the building with AMD or HTMD can achieve good performance. Furthermore, the hybrid control using acceleration feedback was demonstrated to be a promising way for response reduction of buildings.

碩士
國立中興大學
土木工程學系所
96
This thesis primarily deals with the stroke issue of Multiple Tuned Mass Damper (MTMD) which might meet constraint in practice for the vibration control of building. A stroke weighting factor is introduced in the parameter design stage to consider the importance of MTMD stroke. The idea is to obtain an MTMD parameter set that induces acceptable structural control effectiveness but large MTMD stroke reduction. Besides analytical study, this idea was also conducted experimentally by shaking table tests of a full-scale three story building with an actual MTMD prototype. The moving mass of the MTMD prototype is 360 kilograms (2% of total mass of test building) which consists of 5 units of TMDs. Each TMD has the identical damper and spring configurations for economical reason. The mass and the damper coefficient of TMD are adjustable. The shaking table tests were conducted at National Center on Research of Earthquake Engineering (NCREE). Various earthquake inputs were used to verify the structural control efficiency and MTMD stroke reduction. Experimental results demonstrate that reduction in MTMD’s stroke is observed with little sacrifice in roof acceleration control. The test results also show that building responses could be dominated by the higher modes because of low damping ratios. To solve this problem, the smallest unit of TMD is designed to tune the higher mode. Numerical simulation results show the newly designed MTMD is capable of controlling the multiple modal responses of the building. Shaking table tests for the newly designed MTMD is scheduled.

yes
A frequency tuned antenna has been designed to meet the coverage requirements of the DCS, PCS, UMTS and WLAN bands. The antenna consists of a main patch, and a planar inverted L (PIL) slot. The radiator patch is fed, and shorted, using simple feed lines with broadband characteristics. The handset represents the finite ground plane, and a varactor diode is mounted across the middle of the slot for tuning purposes. Initial tuning was obtained by placing lumped capacitors, instead of the varactor, over the radiator. Good agreement is obtained between the predicted and measured input return loss, gain and radiation pattern over the tuned frequency range.
MSCRC

The Blanka tunnel has two boring sections: Brusnice tunnel and Královská obora tunnel. Both tunnels were boring in difficult geologycal conditions, but the geology conditions of these tunnels are not same. Also they had not the same hazards during boring. There was used a spectrum of different technical works with hazard reduction purpose and safety process of boring. There were three serious accidents, wnich everyone made a creater on the surface, but they have not the same causes. This text has a task to describe a geological survey before and during the boring of both tunnels. How other reasons affected the process of boring? How the tunnels were bored? What events preceded the everyone of three major failure? This text does not deal with economical things of boring and effects of specific personal influence on the process of boring. Key words Tunnel, excavation, Blanka, Brusnice, Letná, Stromovka park, Vltava river, underground water, geology, ordovik, New Austrian Tunnelling method, pilot tunnel, calotte, bench, bottom, arche, bolt, lining, grouting, collapse of ceiling, failure, tube, shale, quarzite, soil, loess, ballast, clay

Current seismic design practice promotes inelastic response in order to reduce the design forces. By allowing the structure to yield while increasing the ductility of the structure, the global forces can be kept within the limited bounds dictated by the yield strength. However, during severe earthquakes, the structures undergo significant inelastic deformations leading to stiffness and strength degradation, increased interstory drifts, and damage with residual drift. The research presented in this thesis has three components that seek to address these challenges. To prevent the inelastic effects observed in yielding systems, a new concept “apparent weakening” is proposed and verified through shake table studies in this thesis. “Apparent weakening” is introduced in the structural system using a complementary “adaptive negative stiffness device” (NSD) that mimics "yielding” of the global system thus attracting it away from the main structural system. Unlike the concept of weakening and damping, where the main structural system strength is reduced, the new system does not alter the original structural system, but produces effects compatible with an early yielding. Response reduction using NSD is achieved in a two step sequence. First the NSD, which is capable of exhibiting nonlinear elastic stiffness, is developed based on the properties of the structure. This NSD is added to the structure resulting in reduction of the stiffness of the structure and NSD assembly or “apparent weakening”-thereby resulting in the reduction of the base shear of the assembly. Then a passive damper, designed for the assembly to reduce the displacements that are caused due to the “apparent weakening”, is added to the structure-thereby reducing the base shear, acceleration and displacement in a two step process. The primary focus of this thesis is to analyze and experimentally verify the response reduction attributes of NSD in (a) elastic structural systems (b) yielding systems and (3) multistory structures. Experimental studies on 1:3 scale three-story frame structure have confirmed that consistent reductions in displacements, accelerations and base shear can be achieved in an elastic structure and bilinear inelastic structure by adding the NSD and viscous fluid damper. It has also been demonstrated that the stiffening in NSD will prevent the structure from collapsing. Analogous to the inelastic design, the acceleration and base shear and deformation of the structure and NSD assembly can be reduced by more than 20% for moderate ground motions and the collapse of structure can be prevented for severe ground motions. Simulation studies have been carried on an inelastic multistoried shear building to demonstrate the effectiveness of placing NSDs and dampers at multiple locations along the height of the building; referred to as “distributed isolation”. The results reported in this study have demonstrated that by placing a NSD in a particular story the superstructure above that story can be isolated from the effects of ground motion. Since the NSDs in the bottom floors will undergo large deformations, a generalized scheme to incorporate NSDs with different force deformation behavior in each storey is proposed. The properties of NSD are varied to minimize the localized inter-story deformation and distribute it evenly along the height of the building. Additionally, two semi-active approaches have also been proposed to improve the performance of NSD in yielding structures and also adapt to varying structure properties in real time. The second component of this thesis deals with development of a novel device to control the response of structural system using adaptive length pendulum smart tuned mass damper (ALP-STMD). A mechanism to achieve the variable pendulum length is developed using shape memory alloy wire actuator. ALP-STMD acts as a vibration absorber and since the length is tuned to match the instantaneous frequency, using a STFT algorithm, all the vibrations pertaining to the dominant frequency are absorbed. ALP-STMD is capable of absorbing all the energy pertaining to the tuned-frequency of the system; the performance is experimentally verified for forced vibration (stationary and non-stationary) and free vibration. The third component of this thesis covers the development of an adaptive control algorithm to compensate hysteresis in hysteretic systems. Hysteretic system with variable stiffness hysteresis is represented as a quasi-linear parameter varying (LPV) system and a gain scheduled controller is designed for the quasi-LPV system using linear matrix inequalities approach. Designed controller is scheduled based on two parameters: linear time-varying stiffness (slow varying parameter) and the stiffness of friction hysteresis (fast varying parameter). The effectiveness of the proposed controller is demonstrated through numerical studies by comparing the proposed controller with fixed robust H∞ controller. Superior tracking performance of the LPV-GS over the robust H∞ controller in different displacement ranges and various stiffness switching cases is clearly evident from the results presented in this thesis. The LPV-GS controller is capable of adapting to the parameter changes and is effective over the entire range of parameter variations.