Dissertations / Theses on the topic 'Spring constant'

Devido à necessidade de caracterizar as armadilhas magneto-ópticas (AMO), as quais fornecem amostras densas de átomos frios, e de extrema importância o conhecimento dos valores das constantes mecânicas k e β inerentes ao movimento harmônico super amortecido dos átomos nestas armadilhas. Neste trabalho, obtivemos estas constantes usando a técnica que aplica uma oscilação forçada aos átomos aprisionados através de um pequeno campo magnético oscilante adicional de forma a não perturbar o aprisionamento. Fizemos um estudo destas constantes como função de alguns parâmetros inerentes ao aprisionamento, como por exemplo: intensidade dos feixes laser, gradiente de campo magnético e dessintonia. A manipulação de átomos aprisionados, obtida através da observação de diversas estruturas espaciais dos mesmos, mostra um certo controle sobre estes átomos e a obtenção de valores para a temperatura dos átomos nestas estruturas, permite uma maior compreensão do mecanismo de aprisionamento. Nos detivemos então, na medida da temperatura dos átomos aprisionados em estrutura espacial do tipo anel além de propor um modelo teórico simples capaz de justificar os resultados obtidos.
In order to have precise characterization of magneto-optical traps (MOT), which are used to obtain a dense sample of cold atoms, it is important to measure the mechanical constants k and β of the over-damped harmonic motion that rule the motion of the atoms inside the MOT. In this work, we obtain these constants by applying a small additional a.c. magnetic field that does not perturb the trap d.c. field but forces the trapped atoms to oscillate. We studied the variation of the constants by changing laser intensities, trapping field gradient and detuning. The manipulation of trapped atoms and the observation of several kinds of spatial structures allow one to have a better comprehension of the trapping mechanism. We measured the temperature of the atoms in the ring type structure and a simple theoretical model that explains the results is proposed.

The dynamic properties of several rectangular and V-shaped microcantilevers were investigated. Particular attention was paid to the higher flexural eigenmodes of oscillation. The potential of the higher flexural modes was demonstrated through the use of cantilevers as standalone sensors for adsorbed mass. The mass adsorbed on the surface of a cantilever was in the form of a homogeneous water layer measured as a function of relative humidity. The minimum detectable water layer thicknesses were 13.7 Å, 3.2 Å, 1.1 Å, and 0.7 Å for the first four modes of a rectangular cantilever, clearly demonstrating enhanced accuracy for the higher eigenmodes of oscillation. These thicknesses correspond to minimum detectable masses of 33.5 pg, 7.8 pg, 2.7 pg and 1.7 pg for the first four modes. For quantitative applications the spring constants of each cantilever must be determined. Many methods exist but only a small number can calibrate the higher flexural eigenmodes. A method was developed to simultaneously calibrate all flexural modes of microcantilever sensors. The method was demonstrated for the first four eigenmodes of several rectangular and V-shaped cantilevers with nominal fundamental spring constants in the range of 0.03 to 1.75 N/m. The spring constants were determined with accuracies of 5-10 %. Spring constants of the fundamental mode were generally in agreement with those determined using the Sader method. The method is compatible with existing AFM systems. It relies on a flow of gas from a microchannel and as such poses no risk of damage to the cantilever beam, its tip, or any coating. A related method was developed for the torsional modes of oscillation. Preliminary results are shown for the fundamental mode of a rectangular cantilever. The method can be easily extended to the higher torsional modes, V-shaped cantilevers, and potentially, the flapping modes of the legs of V-shaped microcantilevers.

The response of wide flange steel columns subjected to constant axial loads and lateral blast loads was examined. The finite element program ABAQUS was used to model W8x40 sections with different slendernesses and boundary conditions. For the response calculations, a constant axial force was first applied to the column and the equilibrium state was determined. Next, a short duration, lateral blast load was applied and the response time history was calculated. Changes in displacement time histories and plastic hinge formations resulting from varying the axial load were examined. The cases studied include single-span and two-span columns. In addition to ideal boundary conditions, columns with linear elastic, rotational supports were also studied. Non-uniform blast loads were considered. Major axis, minor axis, and biaxial bending were investigated. The effects of strain rate and residual stresses were examined. The results for each column configuration are presented as a set of curves showing the critical blast impulse versus axial load. The critical blast impulse is defined as the impulse that either causes the column to collapse or to exceed the limiting deflection criterion. A major goal of this effort was to develop simplified design and analysis methods. To accomplish this, two single-degree-of-freedom approaches that include the effects of the axial load were derived. The first uses a bilinear resistance function that is similar to the one used for beam analysis. This approach provides a rough estimate of the critical impulse and is suitable only for preliminary design or quick vulnerability calculations. The second approach uses a nonlinear resistance function that accounts for the gradual yielding that occurs during the dynamic response. This approach can be easily implemented in a simple computer program or spreadsheet and provides close agreement with the results from the finite element method.
Ph. D.

The human body is an intricate network of many highly regulated biochemical processes and cell adhesion is one of them. Cell adhesion is mediated by specific interactions between molecules on apposing cell surfaces and is critical to many physiological and pathological processes like inflammation and cancer metastasis. During inflammation, blood-borne circulating leukocytes regularly stick to and roll on the vessel walls, which consist in part, adhesive contacts mediated by the selectin family of adhesion receptors (P-, E- and L-selectin). This is the beginning of a multi-step cascade that ultimately leads to leukocyte recruitment in areas of injury or infection. In vivo, selectin-mediated interactions take place in a hydrodynamic milieu and hence, it becomes imperative to study these interactions under very similar conditions in vitro. The goal of this project was to characterize the kinetic and mechanical properties of selectin interactions with different physiologically relevant ligands and selectin-specific monoclonal antibodies (mAbs) under a mechanically stressful milieu, using atomic force microscopy (AFM). Elasticity studies revealed that bulk of the complex compliance came from the selectins, with the ligands or mAbs acting as relatively stiffer components in the stretch experiments. Furthermore, molecular elasticity was inversely related to selectin length with the Consensus Repeats (CRs) behaving as Hookean springs in series. Besides, monomeric vs. dimeric interactions could be clearly distinguished from the elasticity measurements. L-selectin dissociation studies with P-selectin Glycoprotein Ligand 1 (PSGL-1) and Endoglycan revealed that catch bonds operated at low forces while slip bonds were observed at higher forces. These results were consistent with previous P-selectin studies and suggested that catch bonds could contribute to the shear threshold for L-selectin-mediated rolling By contrast, only slip bonds were observed for L-selectin-antibody interactions, suggesting that catch bonds could be a common characteristic of selectin-ligand interactions. Force History studies revealed that off-rates of L-selectin-sPSGL-1 (or 2-GSP-6) interactions were not just dependent on applied force, as has been widely accepted but in fact, depended on the entire history of force application, thus providing a new paradigm for how force could regulate bio-molecular interactions. Characterizing selectin-ligand interactions at the molecular level, devoid of cellular contributions, is essential in understanding the role played by molecular properties in leukocyte adhesion kinetics. In this aspect, data obtained from this project will not only add to the existing body of knowledge but also provide new insights into mechanisms by which selectins initiate leukocyte adhesion in shear.

Neste trabalho foram produzidas molas cerâmicas através do processo de moldagem por injeção em baixa pressão, utilizando-se como matéria-prima alumina submicrométrica, aditivada com ligantes a base de ceras. Dentro do tanque de uma injetora Pelstman, estes materiais foram homogeneizados e resultaram em uma suspensão de baixa viscosidade. Entre os objetivos deste trabalho estão a produção de molas cerâmicas helicoidais com perfil circular, a extração dos ligantes orgânicos utilizados durante a moldagem, a pré-sinterização das molas a 1000°C, o acabamento e a sinterização das molas em diferentes temperaturas e a medida de algumas de suas propriedades. A mudança na temperatura de sinterização é uma maneira simples de alterar as propriedades das molas cerâmicas, sem alterar sua composição ou suas dimensões. Foram produzidos três lotes de molas de alumina, que foram sinterizadas a 1550°C, 1600°C e 1650°C, com o objetivo de verificar os efeitos da temperatura sobre a constante de mola e a tensão de fratura. As molas de alumina sinterizada foram obtidas com densidades variando de 94,0% para 97,5% do limite teórico. As constantes de mola foram medidas desde a temperatura ambiente até 1100°C. Os dados obtidos nos ensaios de fratura sob compressão foram analisados de acordo com a estatística deWeibull e o método da máxima verossimilhança. Com o aumento da temperatura de sinterização, de 1550°C até 1650°C, foi observado que a constante de mola e a resistência característica de Weibull das molas de alumina aumentaram em 15% e 32%, respectivamente. Por outro lado, a temperatura de sinterização não teve muita influência sobre o módulo de Weibull. Isso acontece porque as bolhas internas e os defeitos superficiais introduzidos na fase de conformação das molas cerâmicas, possuem um efeito pronunciado na fratura das molas, mais importante do que a redução da porosidade com o aumento da temperatura de sinterização, e são fundamentais para determinar a resistência à compressão das molas cerâmicas.
Submitted by Marcelo Teixeira (mvteixeira@ucs.br) on 2014-06-05T16:49:28Z No. of bitstreams: 1 Dissertacao Rodrigo Antonio Barbieri.pdf: 4044147 bytes, checksum: 645abe8dc3f878007d2ac1715ded418e (MD5)
Made available in DSpace on 2014-06-05T16:49:28Z (GMT). No. of bitstreams: 1 Dissertacao Rodrigo Antonio Barbieri.pdf: 4044147 bytes, checksum: 645abe8dc3f878007d2ac1715ded418e (MD5)
In this work, ceramic coil springs was prepared by low-pressure injection molding using alumina submicrometer-sized powder. The powder are mixed with organic binders in the Pelstman machine tank for several hours resulting in a mixture with low viscosity. This work include the production of helical ceramic springs, thermal debinding, sintering in different temperatures and measure some properties. Sintering temperature was shown to be a simple way to change the spring constant and resistence to compression of ceramics without having a significant impact in the spring´s physical dimensions. Three sets of springs were sintered at different temperatures, from 1550°C to 1650°C, in order to observe the effects on spring constant and fracture stress. Sintered alumina springs were obtained with densities ranging from 94.0% to 97.5% of the theoretical limit. Springs constants were measured from room temperature up to 1100°C. Fracture stress data was analyzed according to Weibull statistics and the maximum likelihood method. Upon increase of sintering temperature from 1550°C to 1650°C, the spring constant and the Weibull characteristic strength of the alumina springs increases by 15% and 32%, respectively. On the other hand, sintering temperature has a negligible influence on Weibull modulus. This is because internal bubbles and surface defects introduced in the production stage of the ceramic springs - more than the reduction in porosity with increasing sintering temperature - are critical in determining the compression resistance of the ceramic springs.

Die Arbeit befasst sich mit der Erforschung und Anwendung der Kelvinsonden-Rasterkraftmikroskopie. Die Technik wird bezüglich der Quantität der gemessenen Werte und der erzielbaren lateralen Auflösung untersucht und auf diverse Probensysteme angewandt. Die so erhaltenen nanoskopischen Werte werden mit markoskopischen Messergebnissen verglichen. Sowohl die elektrostatische Kraft zwischen der Messspitze und der Probenoberfläche als auch deren Gradienten können zur Minimierung der elektrostatischen Wechselwirkung herangezogen werden. Die Detektion des Kraftgradienten zum Aufbau eines Regelkreises erweist sich gegenüber der Kraftdetektion überlegen. Die experimentell ermittelten Befunde werden durch eine Rechnersimulation bestätigt. Diese zeigt die Möglichkeit von quantitativen Ergebnissen für laterale Objektgrößen im Bereich von einigen Nanometern. Im Experiment kann dies gezeigt werden. Es folgt die Anwendung der Kelvinsonden-Rasterkraftmikroskopie: Nanoskopisch ermittelte Werte der Austrittsarbeitsänderung von Metalleinkristall-Oberflächen durch die Adsorption von C_60 entsprechen Literaturwerten, die mit makroskopisch messenden Methoden ermittelt wurden. Sich zeitlich ändernde Oberflächenpotentiale von einer organischen Solarzelle und von lateral unterschiedlich dotiertem Silizium lassen sich quantitativ messen. Der sich bei der Adsorption von Oktadezyl-Phosphonsäure auf Glimmer und Graphit bildende elektrostatische Dipol wird untersucht und abgebildet. Das Wachstumsverhalten und die Austrittsarbeit der organischen Moleküle PTCDA und Alq_3 auf den teilweise mit KBr bedeckten Metallsubstraten Au und Ag wird untersucht. Schlussendlich wird gezeigt, dass mit der Kelvinsonden-Rasterkraftmikroskopie sogar der molekülinterne Dipol der vier Butyl-Gruppen von Tetra-3,5-di-ter-butyl-phenyl-Porphyrinen aufgelöst werden kann.

Submitted by Kilvya Braga (kilvyabraga@hotmail.com) on 2018-04-23T13:32:14Z No. of bitstreams: 1 ROANA D'ÁVILA SOUZA MONTEIRO - DISSERTAÇÃO (PPGEM) 2015.pdf: 3977570 bytes, checksum: e1760f7cd8bdc07cce68f5b1aedd33a2 (MD5)
Made available in DSpace on 2018-04-23T13:32:14Z (GMT). No. of bitstreams: 1 ROANA D'ÁVILA SOUZA MONTEIRO - DISSERTAÇÃO (PPGEM) 2015.pdf: 3977570 bytes, checksum: e1760f7cd8bdc07cce68f5b1aedd33a2 (MD5) Previous issue date: 2015-08-31
Capes
As Ligas com Memória de Forma (LMF) constituem uma classe de materiais metálicos que possuem a capacidade de recuperar uma deformação pseudo plástica, introduzida por aplicação de carga mecânica, e retornar à sua forma original através de um simples aquecimento. O principal interesse nos atuadores de LMF utilizados no formato de molas helicoidais reside no grande deslocamento proporcionado pelo fenômeno de Efeito Memória de Forma (EMF), que permite a realização de trabalho mecânico quando este componente é submetido a diferentes condições de temperatura e cargas mecânica. No caso de elementos de LMF em estado de superelasticidade (SE) na temperatura ambiente, quando a carga mecânica é aplicada e mantida sob o material, a deformação originada pela formação de martensita induzida por tensão poderá também ser revertida por meio de um aquecimento. Nesse caso, tem-se um EMF em um elemento de LMF originalmente superelástico. Nesse contexto, o objetivo deste trabalho é realizar a caracterização eletromecânica de uma mini mola superelástica de LMF NiTi (Nitinol) quando submetida a um carregamento mecânico constante, avaliando a influência da taxa de variação da corrente elétrica e do aumento da carga mecânica nas temperaturas de transformação, além de determinar o comportamento do deslocamento com a variação de resistência elétrica. Para isso, foi desenvolvida uma plataforma experimental capaz de submeter a mini mola a carregamento mecânico constante (peso) e sinais de corrente elétrica variáveis com o tempo. Verificou-se que, para todas as cargas mecânicas e níveis de corrente elétrica, os resultados para a taxa de variação da corrente elétrica mais lenta (6 mA/s) apresentou uma melhor resposta em deslocamento e na variação da resistência elétrica quando comparados com a taxa mais rápida (12 mA/s), embora esta última resulte em um comportamento histerético mais estreito (resistência elétrica versus deslocamento). Também foi observado um aumento das temperaturas de transformação com o aumento da carga mecânica, como esperado pela lei de Clausius-Clayperon para LMF. Finalmente, foi verificada uma relação praticamente linear entre a variação do deslocamento e a variação de resistência elétrica, no aquecimento e no resfriamento.
The Shape Memory Alloys (SMA) are a class of metallic materials that have the ability to recover pseudo plastic deformation introduced by the application of mechanical load, and return to original shape by heating. The main interest in the SMA actuators used in the form of coil springs lies in the large displacement provided by the shape memory effect (SME) phenomenon, which allows performing mechanical work when the component is subjected to varying conditions of temperatures and mechanical loads. In the case of SMA elements in a state of superelasticity (SE) at room temperature, when mechanical load is applied and maintained on the material, the deformation caused by the formation of stress induced martensite can be reversed by heating. In this case, we have a SME in a SMA element originally superelastic. In this context, the objective of this work is to realize the electromechanical characterization of a superelastic mini coil spring of Ni-Ti SMA (Nitinol), when subjected to a constant mechanical loading, evaluating the influence of the electric current rate, the influence of mechanical load on the phase transformation temperatures, and determining the displacement behavior to the variation of electrical resistance. For this, an experimental platform was developed to submit the mini spring under constant load (dead weight) to electric current signals varying with time. It was found that for all mechanical loads and electrical current levels, the results for the slower rate of change electrical current (6 mA/s) showed a better response in displacement and the variation in the electrical resistance when compared to faster rate (12 mA/s), although the faster rate present a narrower hysteretic behavior (electrical resistance vs displacement). There was also verified an increase in phase transformation temperatures with increased mechanical load, as expected by the Clausius-Clayperon law for SMA. Finally, a practically linear relationship was found between the change in displacement with the variation in electrical resistance, during heating and cooling.

Using the tools of structural and network analysis developed by Ronald R. Burt and others, this study investigated the communication patterns among corporate officers of American Telephone and Telegraph Corporation (A.T. & T.) and United Telecommunications Corporation (Sprint). Data on contacts, efficiency, network density, and constraint indicate that opportunities for power and constraint have remained relatively stable at United Telecommunications between 1980 and 1990. A. A.T. & T., on the other hand, was more affected by the drastic changes in the telecommunication industry. The span of A.T. & T. has grown smaller and the potential for constraining relations among A. T. & T. and financial institutions has increased during the period 1980 and 1990.

碩士
逢甲大學
紡織工程所
92
The envisioned benefits of a composite spring are the reduction of weight, better chemical resistance and electrical insulation. The feasibility of replacing a metal helical compression spring with a composite one having the same characteristics has been studied. Four different types structure of composite helical spring that are unidirectional laminates (AU), rubber core in the unidirectional laminates (UR), braid outer layer cover unidirectional laminates (BU),and rubber core in unidirectional laminates with braid outer layer (BUR)structures respectively, and they have been discussed about the factors included rubber core and the braided outer layer applied on spring’s structure as well as their effects on structure mechanical properties, spring constant and fatigue performance. According to the experimental results, the composite helical spring with rubber core can increase its compression failure load about 12％. The braided outer-layered structure can not only add 18％of compression failure load, but increase spring constant approximately 16％. So the BUR structure that consists of rubber core and braided outer-layer composite helical spring obtains the highest mechanical properties, which the compression failure load is 336.2 kgf, the spring constant is 16.27 kgf/mm. In addition, after a hundred thousand cycles fatigue test, the carried load of BUR spring decreases within 5％ and which can be accepted by industry standard, in general.

碩士
建國科技大學
機械工程系暨製造科技研究所
100
This investigation conduct the basic design about constant pressure gas spring compressed air channel problem. The important term will focus on the performance for the machinery and for the compressed air consumption. In the meantime, the load and impact load is studied for the vibration of the constant pressure gas spring. The results are not the same owing to different design about flow channels. Suitable air flow channel design may sustain same force only a little compressed air. This investigation will use pressure sensor and data acquisition to measure the transient pressure for air chamber of the cylinder and use flowmeter to measure the consumption for the compressed air. The final results for the investigation is 0.015mm clearance between cylinder and piston, the length of the piston is 80mm, the width of flow channel is 3mm, the depth of the channel is 5mm and distance between channels is 4.5mm. These are suitable design for 60mm cylinder diameter for constant pressure gas spring. Commercial package FLUENT is cooperated to simulate compressed air in the multi-stage cavity flow, study the compressed air flow behavior in the constant pressure gas spring.

博士
國立清華大學
動力機械工程學系
96
Abstract Atomic force microscope (AFM) has many applications in science research under nano-scale or micro-scale. The mechanical properties of nanostructures can be measured from the deformation of cantilever of atomic force microscope. The accuracy of the mechanical properties depends on the precise calibration of the spring constant of AFM cantilevers. Thus, the spring constant of cantilever must be calibrated before measurement. Many parameters such as coating layers, material properties, geometries, tilt angles, and landing forces, significantly affecting the spring constant of AFM were investigated in this study. The results obtained from the finite element method were compared with those determined from the existing equations and from experiment. The results calculated from our finite element model show good agreement with experimental data and with the ones from other published papers. The results show that both the bending and torsional spring constants of NT-MDT CS12 rectangular cantilevers increased with the increasing thickness of aluminum coating layer. The coating layers of AFM cantilevers should not be neglected, especially for thinner cantilevers. The material properties directly affect the deformation characteristics of AFM cantilevers. The bending spring constant is proportional to the Young’s modulus and increases nonlinearly with Poisson’s ratio. However, the lateral spring constant decreases with increasing Poisson’s ratio. When the anisotropic material property of crystal silicon is considered, the commercial software CASTEP�� was adopted to obtain the anisotropic stiffness matrix of crystal silicon. Then, the anisotropic material matrix can be used in the finite element analysis. From the simulation results, the anisotropic material property significantly affects the spring constants of AFM cantilevers. Two equations were proposed to obtain the spring constants and the resonant frequencies of crystal silicon AFM cantilever with the axis located at different cantilever-crystal angles. The geometry variations due to the fabrication tolerance were also studied by finite element method. The thinner and narrower cantilevers are more sensitive to the force measurement; however the geometry nonlinearity should be considered under large loadings to improve the accuracy of measurement. Moreover, the resonant frequency shift caused from the mass of image tip was studied to reduce the error of spring constant calculation. During the force measurement process, the loading condition of the cantilever is very complex. During the cantilever landing process, the effects of combined loadings and pre-stress were analyzed by the finite element method. The landing force significantly affects the spring constant of AFM cantilevers, and should be considered. In order to precisely obtain the deformation behavior and spring constant of AFM cantilevers, the above mentioned parameters should be considered in the analysis. Once the spring constants of AFM cantilevers were obtained, they were used to measure the mechanical properties of carbon nanotubes. The effects of loading positions and geometries on the mechanical properties measurement were also carried out by finite element method in this study.

碩士
國立臺灣大學
工程科學及海洋工程學研究所
107
Moving-coil earphone is an integration of electrical, mechanical and acoustical system. Its performance is determined by the collaboration of these systems. Mechanical system converts electrical energy to acoustical energy, and diaphragm system, which composed of diaphragm and diaphragm rim is part of it. At low frequency, mechanical system can be simulated by an equivalent mass-spring-damper system. The equivalent mass, spring constant, and damping coefficient determine the performance of mechanical system at this frequency range. However, the equivalent spring constant of diaphragm system cannot be known before the earphone is assembled. Therefore, in this research, acoustic and electrical impedance method are adopted to determine the equivalent spring constant of the diaphragm system. In acoustic impedance method, the specific acoustic impedance of diaphragm system with an air-backed cavity was measured, and through curve fitting, the equivalent spring constant can be obtained. In electrical impedance method, the resonant frequency of system comprising of loudspeaker, cavity, and diaphragm system was measured, and by iteration, the equivalent stiffness value can be acquired. It can be shown from the result that the equivalent spring constant measured by the respective method are close in the order of magnitude and these two methods are feasible.

碩士
國立中正大學
光機電整合工程所
97
In this thesis, the historical background and development of an optical tweezers system were first reviewed. The introductory concepts for the basics of trapping a particle, the fundamental principles of operations and the detailed components for a typical optical tweezers were also presented. Subsequently, trapping and manipulation of polystyrene micro particles, bundles of polymer nanowires, and yeast cells were executed and demonstrated by an optical tweezers system set in lab. To describe the trapping force of an optical tweezers system quantitatively, characterization of the system’s spring constant was crucial. The main focus of this study was thus placed on precisely calibrating the spring constant of an optical tweezers system. The particle grasped by an optical tweezers is analogous to the way a particle was trapped in a potential well. Based on descriptions of the Brownian motion, both the Boltzmann distribution method and the power spectrum density method were employed to measure the spring constant. And, based on the employed optical tweezers system for trapping a polystyrene particle with diameter of 2.88um and under an laser power of 70 mW, the characterized spring constants for the two methods were 21.16±3pN/um and 19.96±2.6pN/um, respectively. Quantitatively, they were very close. Results further showed that the spring constant was increased linearly with the enhancement of the laser power. The effect of the particle size on the spring constant was also studied and discussed in this study. Once the spring constant is precisely calibrated, the optical tweezers system can be applied more directly to precision measurements and micro fabrications.

碩士
朝陽科技大學
資訊與通訊系碩士班
100
Cardiovascular disease is the leading cause of mortality in the developed world. Current social changes in eating habits and the increasing economic pressures of life gradually results in the production of many diseases of civilization, such as heart disease, stroke, arteriosclerosis and etc. In this study, we measured the finger pulse of photoplethymography ( PPG) at one-point using a non-invasive way, and measured the radial pulse using pressure sensors. We then calculated the spring constants of both signals. We recruited forty- four subjects in Taichuang hospital (22 men and 22 women), with an age range of forty to eighty-five years old. Results imply the positive correlation of spring constant with correlation coefficient = 0.77 between PPG and radial pulse. In addition, p value < 0.01 implies the significant correlation. The result also shows the feasibility to use the PPG as the index signal in evaluating the arterial stiffness for the application in home care or telemedicine.

博士
朝陽科技大學
資訊管理系博士班
102
Arteriosclerosis must be detected and treated in its early stage to prevent the occurrence of cardiovascular disease. Particularly, this disease is prone to befall the carotid and coronary arteries. Early detection will help reduce the severity of the disease as the complications have caused a high mortality, so it is the prime task to develop the new technology for early diagnosis or new technique for examination at this moment. This study adopted the non-invasive pressure sensor to measure the radial artery of atherosclerosis patients, analyze the radial artery pressure waveform, and calculate the spring constant. Furthermore, the spring constant, the carotid ultrasound index detected in the hospital and atherothrombotic risk factors (age, blood pressure, blood lipids, diabetes, and smoking) were analyzed. We collected sixty cases. The binary classification of ROC curve analysis was used to analyze the relationship between the spring constant and the abnormality of carotid artery index. The area under ROC curve up to 0.605 > 0.5 (AUC= 0.605 ± 0.077) indicates that the detected spring constant is a good determinant against right ICA/CCA index. The area under the ROC curve up to 0.504 > 0.5 (AUC=0.504 ± 0.079) indicates that the detected spring constant is a preliminary determinant against left ICA/CCA index. Regarding CCA index, the area under the ROC curve increases up to 0.727 > 0.5 (AUC = 0.727 ± 0.076), and that indicates the spring constant a good discernment for carotid abnormality. The verification of such spring constant can be applied for the patients with carotid disorder. Furthermore, the spring constant can be an indicator for atherosclerosis patients. Because the spring constant is a fast as well as effective method, it is hoped that the result can be of use to medical professionals and sheds some light to non-invasive arteriosclerosis diagnosis as well as lift medical quality.

碩士
國立陽明大學
生醫光電工程研究所
96
This thesis consists of two parts. In the first part, we report the application of a set of parallel dual tweezers, one stationary and one movable, to trap a polystyrene bead (suspended in de-ionized water) and drag it away from one of the trap centers beyond the linear (Hooke’s spring) regime, to probe the nonlinear optical force constants associate with the optical trap. Mathematically, we represent the nonlinear spring by a 5th order polynomial, with all the even orders absent because of the axial symmetry of the optical trap. By fitting the experimental data to the polynomial, the 3rd order and the 5th order nonlinear optical force constants for different bead size (diameter = 1.5 μm, 1.04 μm, 0.59 μm) at different optical trapping power (2 mW, 4 mW, and 6 mW) were obtained. For example, for a 1.04 μm polystyrene bead trapped in optical tweezers with trapping laser wavelength λ = 1064 nm, focused by a N.A. = 1.25 100X oil immersion objective, and with 2.0 mW optical power, the 3rd order and the 5th order nonlinear optical force constants were determined to be -85.86 ± 8.1 pN/μm-3 and 63.18 ± 10.8 pN/μm-5, respectively. Besides, useful information including the linear range, the maximum trapping force, and the error associated with the linear approximation of trapping force when the particle was in the nonlinear regime was deduced from the experimental data for each polystyrene bead size. In the 2nd part, we report the application of oscillatory optical tweezers to trap and oscillate three different types of E. coli, namely, JW1923 (normal but no flagellum), BW25113 (normal), and EHEC (Enterohemorrhagic E. coli, EHEC), suspended in 0.2% LB agar, to probe the interaction between E. coli and the agar substrate in terms of the elasticity modulus G'. We oscillated the optical trap center (via an oscillating mirror mounted on a pzt-stage driven by a sinusoidal signal from a lock-in amplifier) at an amplitude of approximately 34 nm and a frequency of 10 Hz, and measured the amplitude and the relative phase of the oscillating E. coli. From the experimental data, the interaction between E. coli and the substrate, characterized by the elasticity modulus G', were determined to be 64.53 ± 12.56 dyne/cm2, 54.8 ± 8.21 dyne/cm2, and 25.91 ± 7.71 dyne/cm2,respectively, for the three types of E. coli, JW1923, BW25113, and EHEC, all suspended in 0.2% LB agar. When the experiments were repeated in a mixed solution of 0.2% LB agar and galactose (10 mM), the elasticity modulus G' reduced to 55.08 ± 10.67 dyne/cm2, 42.4 ± 11.67 dyne/cm2, and 19.94 ± 8.4 dyne/cm2, respectively, for the three types of samples. The significance of the correlation between the elasticity modulus G' measured by this technique for three types of E. coli suspended in 0.2% LB agar, and the observed percentage of E. coli division in a sliding mode (27%, 13%, and 0%, respectively, for the three types of samples cultured in the same medium), requires further investigation.

The purpose of this study is to provide the necessary technical background and data for the development of a suspension system for a recumbent bicycle. For this reason, the customer requirements-design criteria for the development of the suspension system were set, and several static and dynamic tests were conducted on the bicycle's suspension components in order to determine their shock absorption properties. The shock absorption properties of the bicycle's components can be used as means of evaluating the specifications of the suspension system that will satisfy the established design criteria best. In addition, a test machine that can be used for damping coefficient and spring constant measurements was designed to provide further assistance with the analysis of the damping and elastic properties of the recumbent bicycle's suspension components. It was designed so that it can also be used for similar testing of other materials and parts used in the bicycle industry. The subject of this study was BikeE, a recumbent bicycle that was developed by Professor D. G. Ullman and the BikeE Corporation in 1992.
Graduation date: 1995

Dissertação de Mestrado Integrado em Engenharia Mecânica apresentada à Faculdade de Ciências e Tecnologia da Universidade de Coimbra
Pretende-se com esta tese, estudar e melhorar a cronometria de um relógio mecânico, introduzindo e combinando conceitos, mais ou menos recentes, desenvolvidos pelas indústrias relojoeiras de todo o mundo como o turbilhão tri axial, a espiral dupla e o mecanismo de força constante. Individualmente, figuram em diversos relógios mecânicos presentes no mercado e possuem todos, a característica de serem mecanismos implementados ao movimento com vista à melhoria cronométrica do mesmo. Cada um destes mecanismos acrescenta um valor monetário considerável aos relógios a que estão associados, com a promessa que a sua presença significa performances mais elevadas de cronometria. Sendo que, em teoria, os conceitos parecem fazer sentido, aparentemente o mercado carece de estudos conclusivos acerca das suas reais eficácias. É efetuado neste sentido um estudo teórico de cada um destes mecanismos, a trabalharem individualmente e em conjunto, num movimento criado pelo autor para o efeito, para que se retirem resultados conclusivos acerca da eficácia dos mesmos. O desenvolvimento desta tese passou pela criação de um movimento em base SolidWorks, onde foi implementado cada um dos mecanismos. O movimento foi desenhado de acordo com todas as regras tradicionais de relojoaria, tendo o autor, recorrido às normas NIHS (Normas da indústria relojoeira Suíça), e a peças chave catalogadas, com vista a tornar o movimento o mais realista e fiável possível. Toda a estrutura de suporte ao movimento também foi criada, mais uma vez, tornando o movimento, e assim o relógio projetado, num produto final pronto a ser fabricado e comercializado. A segunda fase da tese centrou-se nos aspetos cronométricos do movimento projetado. Foi inicialmente efetuada uma breve revisão bibliográfica, onde são descritos e estudados cada um dos fatores responsáveis pela perda das propriedades cronométricas de um relógio mecânico, como a amplitude e frequência, e posteriormente, apresentadas soluções para cada um desses problemas, soluções estas, que foram adotadas no movimento anteriormente projetado. Após este estudo, o autor, centrou-se na obtenção dos resultados cronométricos acerca do comportamento do movimento criado face a um movimento comum, que também foi desenhado, embora apenas nas suas partes fundamentais ao estudo. Para o efeito, recorreu ao programa de simulação dinâmica Simulink, que tem por base a linguagem Matlab, mas que simplifica a construção da programação ao permitir a introdução de dados por blocos à semelhança de um fluxograma. Neste programa dois modelos foram criados, um que simula o comportamento do movimento projetado, e outro que simula o comportamento de um movimento comum. As variáveis introduzidas em cada um destes modelos controlam diretamente os aspetos anteriormente estudados na revisão bibliográfica, que influenciam a cronometria, e os valores destas foram obtidos direta, e indiretamente do projeto efetuado em Solidworks. Daí a necessidade do mesmo. Os outputs obtidos nos dois modelos, a frequência e a amplitude do órgão oscilador, indicaram quão preciso cada um dos dois movimentos é face ao outro, permitindo assim, retirarem-se conclusões acerca das propriedades cronométricas de cada um e da eficácia que os conceitos introduzidos (no movimento projetado) têm num movimento comum. Os resultados a que se chegou após a comparação, indicam favoravelmente que, em teoria, os diferentes conceitos funcionam, quer estejam a trabalhar em conjunto quer estejam a trabalhar em separado. **O mundo da relojoaria é um nicho muito específico, contendo um vocabulário próprio muito extenso, e às vezes, de difícil compreensão. Alguns dos conceitos que foram introduzidos, bem como alguns dos termos utilizados, são da exclusividade desse mundo, pelo que, para o leitor que não esteja habituado aos mesmos, o texto desta tese pode tornar-se um verdadeiro desafio. Assim, antes de iniciar a leitura da mesma, o autor, aconselha a passar uma revista pelo apêndice 1, que nada mais é que um glossário ilustrado de relojoaria.
The aim of this thesis is to study and improve the timing of a mechanical watch and matching introducing more or less recent concepts developed by the watchmaking industries worldwide like the tri axial tourbillon the double hairspring and the mechanism of constant force. Individually listed in various mechanical watches in the market and all of them have the characteristic of being implemented mechanisms to movement with an objective in improving its timekeeping. Each of these mechanisms adds considerable value to mechanical watches with the promise that their presence means higher performances in timing. While in theory these concepts seem to make sense apparently the market lacks conclusive studies about its real efficacy. A theoretical study of each of these mechanisms is done working individually and together in a movement created by the author with the objective of withdrawing conclusive results about the effectiveness of them. The development of this thesis began by creating a movement based on SolidWorks where each mechanism has been implemented. The move was designed in accordance with all the rules of traditional watchmaking with the author consulting NIHS standards (Standards of Swiss watchmaking industry), and the key pieces catalogued in order to make the most realistic and reliable movement possible. The entire support structure (case) is also designed once again making the movement and thus making the watch designed in a final product ready to be manufactured and marketed. The second phase of the thesis focused on the chronometric aspects of movement designed. Was initially performed a brief literature review which are described and analysed each of the factors responsible for the loss of chronometric properties of a mechanical watch such as the amplitude and frequency and then presented solutions for each and every one of these problems. These solutions have been adopted in movement previously designed. After this study, the author focused on obtaining chronometric results of the behaviour of the created movement in comparison to a common movement which was also designed but only in its basic parts needed for the study. For this purpose the author used the dynamic simulation program named Simulink which is based on the Matlab language, but that simplifies the construction of the program to allow the introduction of data blocks similarly to a flowchart. In this program, two models were created, one which simulates the behaviour of the designed movement and another to simulate the behaviour of a common movement The variables to be introduced in each of these models directly control the previously studied aspects that influence the timing and the amounts of these were obtained directly and indirectly from the project done in SolidWorks. Hence the need of it. The outputs from the two models, the frequency and amplitude of the oscillator unit, indicated how accurate each of the two movements is compared to another thus allowing to withdraw conclusions from chronometric perspective about the properties of each and efficiency that the concepts introduced (in the projected movement) have in a common movement. The obtained results after comparing favourably indicate that in theory the different concepts work whether they are working together or are working separately. The world of horology is a very specific niche containing a very large and difficult to understand vocabulary. Some of the concepts that were introduced as well as some of the terms used are exclusive to this world so for the reader who is not accustomed to them the text of this thesis can become a real challenge. So before you start with reading the author kindly advises to spend an overall reading at Appendix 1 which is nothing more than an illustrated glossary of watchmaking.

碩士
國立臺灣科技大學
機械工程系
105
This study explores the design possibility of a spring-type rigid-link mechanism that produces a constant torque. The mechanism we aim to devise should have rigid links and a spring only without the use of flexible rods and cams. In this thesis, we firstly reviewed the development of the torsional mechanisms. We then put forward two possible mechanism concepts to output constant-torque, and use these two concepts to design three nearly constant-torque mechanisms. Then we analyzed the output torque of each mechanism, and then use Matlab and Adams software to verify the design results. Finally, we chose the most feasible design, performing its geometrical optimization. The design result shows that the average fluctuation of the output torque is only 5.67% during 60 degrees to 110 degrees of the crank motion.

碩士
龍華科技大學
工程技術研究所
98
Pneumatic system has been widely used in the industry as an essential power supply. For properly operating of the system, air pressure needs to be maintained at a stable range. However, air pressure is subject to change due to the load variation of the system. A pressure regulator is therefore installed to soothe the instability of the pressure. Pressure regulator is controlled by two springs, which acting on the valve of the regulator adjusts valve position for pressure control. The purpose of thisresearch is to propose a design method to determine the spring constants for the pressureregulator. Pressure distribution obtained from computation is adopted for spring force balance. Least square method is used to obtain the adequate spring constants based on the opening of the vale and forces on the valve such that outlet pressure can be maintain at constant value. Two different values, i.e. 200kPa and 400 kPa are considered just for verification purpose. To enhance the lifetime of the system, a de-humidifier is also installed to keep air clean and dry. It is believed that the de-humidifier creates a swirling velocity of the air thus generates centrifugal force to the water droplet for removing. This research adjusts the angle of the guide vane of the de-humidifier, and performs flow field simulation on the de-humidifier. The result shows that the smaller the angle of the guide vane is the larger its swirling velocity is, which could mean a better de-humidifying effect, however, larger pressure drop is obtained.

Different methods for the determination of cantilever properties in non-contact atomic force microscopy (NC-AFM) are under investigation. A key aspect is the determination of the cantilever stiffness being essential for a quantitative NC-AFM data analysis including the extraction of the tip-surface interaction force and potential. Furthermore, a systematic analysis of the displacement noise in the cantilever oscillation detection is performed with a special focus on the thermally excited cantilever oscillation. The propagation from displacement noise to frequency shift noise is studied under consideration of the frequency response of the PLL demodulator. The effective Q-factor of cantilevers depends on the internal damping of the cantilever as well as external influences like the ambient pressure and the quality of the cantilever fixation. While the Q-factor has a strong dependence on the ambient pressure between vacuum and ambient pressure yielding a decrease by several orders of magnitude, the pressure dependence of the resonance frequency is smaller than 1% for the same pressure range. On the other hand, the resonance frequency highly depends on the mass of the tip at the end of the cantilever making its reliable prediction from known cantilever dimensions difficult. The cantilever stiffness is determined with a high-precision static measurement method and compared to dimensional and dynamic methods. Dimensional methods suffer from the uncertainty of the measured cantilever dimensions and require a precise knowledge its material properties. A dynamic method utilising the measurement of the thermally excited cantilever displacement noise to obtain cantilever properties allows to characterise unknown cantilevers but requires an elaborative measurement equipment for spectral displacement noise analysis. Having the noise propagation in the NC-AFM system fully characterised, a proposed method allows for spring constant determination from the frequency shift noise at the output of the PLL demodulator with equipment already being available in most NC-AFM setups.