Dissertations / Theses on the topic 'Plane-parallel plate'

Обсяг звіту становить 56 сторінок, міститься 25 ілюстрацій, 17 таблиці. Загалом опрацьовано 22 джерел. Актуальність: контроль та швидка оцінка характеристик параметрів кровотоку є важливим атрибутом правильної діагностики пацієнта, а в особливості неівазивним методом вимірювання, так як сприйняття організму чужорідного тіла може вести до неприємних наслідків. Мета: недорогий та надійний лазерний вимірювач швидкості кровотока, як для лабораторних дослідів, так і для повсякденного контролю пацієнта. Завдання: 1. Огляд та аналіз літератури, що стосується лазерних вимірювачів швидкості кровотоку. 2. Огляд та аналіз інтелектуальної власності сучасних лазерних вимірювачів швидкості кровотоку. 3. Побудова оптично-функціональної схеми приладу. 4. Підбір елементів для реалізації швидкоміра. 5. Моделювання лазерного вимірювача кровотоку.
The volume of the report is 56 pages, contains 25 illustrations, 17 tables. In general, 22 sources were processed. Relevance: control and rapid assessment of the characteristics of blood flow parameters is an important attribute of proper diagnosis of the patient, and in particular a non-invasive method of measurement, as the perception of a foreign body can lead to unpleasant consequences. Purpose: inexpensive and reliable laser blood flow meter, both for laboratory experiments and for daily monitoring of the patient. Task: 1. Review and analysis of the literature related to laser blood flow meters. 2. Review and analysis of intellectual property of modern laser blood flow meters. 3. Construction of the optical-functional scheme of the device. 4. Selection of elements to the optical-functional scheme of the flowmeter. 5. Simulation of a laser blood flow meter.

The plane parallel homogeneous (PPH) bias is defined as the difference between the plane parallel cloud albedo, calculated for homogeneous cloud optical depth distributions, and the independent pixel (IP) albedo, which allows for optical depth variability, but assumes that individual cloudy columns transfer solar radiation as plane parallel slabs (horizontal photon transport is neglected). Estimates of the PPH bias from extensive Advanced Very High Resolution Radiometer (AVHRR) observations are provided for areas similar in size to weather and climate model gridboxes. The goal is to investigate conditions and assumptions influencing the PPH bias, and to suggest methods to correct for it.
Visible PPH biases vary from about 0.02 to 0.30, depending on area size, view/sun geometry, and other factors influencing optical depth retrievals and albedo calculations. Broadband PPH biases are slightly smaller than visible biases; broadband absorptance biases are about an order of magnitude smaller. Approximate estimates of the bias in broadband reflected flux at cloud top often exceed 30 Wm$ sp{-2}$ for near-nadir measurements, suggesting that the assumption of cloud homogeneity produces errors that cannot be ignored in climate studies.
Solar geometry affects the PPH bias not only through the direct dependence of albedo on solar zenith angle, but also through systematic changes in the apparent mean and variance of optical depth arising from the neglect of 3-d effects in satellite radiance inversions. PPH biases decrease with data resolution, increase when atmospheric radiative effects are accounted for in optical depth retrievals, and are only slightly affected by water cloud microphysics. PPH biases are also shown to differ substantially between the forward and backward scattering directions, and between large-scale models with and without provision for fractional cloudiness.
A large fraction of the PPH bias is removable by: (1) adjusting regionally averaged optical depths with the reduction factor of Cahalan et al. (1994a), and (2) fitting observed optical depth distributions with lognormal and (to a lesser degree) gamma distributions. These methods require the logarithmic mean and variance of optical depth, which are parameterized as a function of regional mean optical depth and cloud fraction, quantities routinely available in climate models.

High skirt selectivity and extended out-of-band rejection is a major challenge for the successful progress of in-line microwave filters. This thesis presents novel filter realizations with improved performance, compatible with the standard single thin all-metal insert in a split-block housing and therefore maintaining the low-cost fabrication characteristics. In addition, significant filter performance improvement is achieved. The synthesis procedure implemented for the filter concept consists of a few steps. Some preliminary steps are a rigorous characterization of a double-ridge coaxial waveguide, and the modelling of an equivalent circuit model for the parallel coupled ridge waveguide devised in the filter concept. From these elements, a full wave electromagnetic analysis shows that parallel-coupled asymmetric ridge waveguides produce strongly dispersive coupling which introduces a transmission zero. Later on this property is extended to parallel-coupled asymmetric ridge waveguide resonators, where it is demonstrated that it is possible to independently control the coupling coefficient and the frequency of the transmission zero. This allows the realization of pseudo-elliptic narrowband in-line bandpass filters in E-plane technology. A general synthesis procedure for high order filters is outlined and numerical and experimental results are presented for validation. The elements employed for the synthesis procedure of the bandpass prototypes are also applied to investigate structures suitable for different applications. In particular, stopband and dual stopband filters are presented with numerical and experimental results. Finally, the study of a microwave chemical/biochemical sensing device for the characterization and detection of cells in chemical substances and cells in solution in micro-litre volumes is also reported.

To optimize delivery of radiation therapy treatments, accurate knowledge of absorbed dose in the clinical beam is essential. In this work we investigated issues related to the use of different types of ionization chambers for accurate radiation dosimetry. We determined values of Pwall at 60Co for plane-parallel chambers and used them to derive the conversion factors kecal k'R 50 or kQ for a 20 MeV electron beam. Our results agreed within 0.4% with kQ values given in the IAEA TRS-398 protocol, but differences of up to 1.8% were found between our kecalk' R50 values and those in the AAPM TG-51 protocol. We also investigated the behavior of two liquid-filled ionization chambers in megavoltage photon beams, examining stability, ion recombination and beam quality dependence. Methods for determining and correcting for recombination were investigated. Preliminary results show that the energy dependence of a liquid-filled chamber can typically be limited to less than 1% for megavoltage photon beams.

The Mueller scattering matrix elements (S(ij)) and the cross-sections for the scattering of an electromagnetic plane wave from two infinitely long, parallel, circular cylinders at oblique incidence are derived. Each cylinder can be of arbitrary materials (any refractive index). The incident wave can be in any polarization state. To find the scattering coefficients, which are essential for calculating S(ij) and the cross-sections, the multiple scatterings were taken into account for all orders such that the 'incident' field of one cylinder is the true incident field plus the scattered field from the other cylinder. The formal solutions of the scalar wave equation are obtained in the three regions; the region outside the two cylinders, the region inside each cylinder and the scattering coefficients are found by satisfying the boundary conditions. A computer program was written. The scattering coefficients are calculated from a matrix equation. This is the first comprehensive study of the two cylinder problem. Special cases are considered in comparison with other published works. Calculations are shown of S(ij) and of cross-sections for some selected cases of configurations of the two cylinders.

Measurements of absorbed dose to water in megavoltage electron beams are carried out with cylindrical or plane-parallel ionization chambers. The perturbation factor associated with plane-parallel ionization chambers that have sufficiently large guard rings is assumed to be unity. The NACP-02 chamber is one such chamber that we have investigated in order to determine if this assumption is valid. By performing Monte Carlo simulations with the EGSnrc code, water-to-air Spencer-Attix stopping powers and perturbation factors were calculated in water with a detailed model of the NACP chamber that was validated through results obtained from measurements and simulations. These were determined for electron beam energies between 4 MeV and 19 MeV for a clinical and PSDL linear accelerator. The overall perturbation factor was found to decrease with energy at dref from 1.015 at 4 MeV to 1.004 at 19 MeV and increase with depth for a fixed beam quality.

For megavoltage electron beams, current dosimetry protocols assume well-guarded plane-parallel ionization chambers have electron perturbation correction factors of unity. Papers by other researchers have shown the contrary. The National Physical Laboratory (NPL), Teddington UK, has an electron calibration service that requires knowledge of the ratio of perturbation factors in water to graphite for their NACP-02 chamber. Using the Monte Carlo code EGSnrcMP, perturbation correction factors at depth zref in graphite for the NPL's Radiation Dynamics linac 4 – 19 MeV were calculated. These results combined with those in water calculated by Zakikhani (2006) showed that only the ratio of perturbation factors in water to graphite for the 4 MeV and 12 MeV beams, at 1.0080 ± 0.27 % and 1.0071 ± 0.28 %, were significantly different from unity. Perturbation correction factors in water and graphite for the Varian clinical linacs 4 – 18 MeV were also investigated. Important issues that arose requiring further study included the discrepancy in results caused by 1 keV vs. 10 keV transport cutoffs and whether the depth of the effective point of measurement should account for the phantom equivalent thickness of the chamber window.
Pour les faisceaux d'électrons de haute énergie (MV), les protocoles de dosimétrie actuels supposent que les chambres d'ionisation à plaques parallèles ont des facteurs de correction de perturbation électronique égaux à l'unité. Plusieurs articles d'autres auteurs ont démontré le contraire. Le National Physical Laboratory (NPL), Teddington Royaume-Uni, possède un service d'étalonnage qui requiert de savoir les facteurs de perturbation de l'eau par rapport au graphite pour leur chambre NACP-02. A l'aide du code Monte Carlo EGSnrcMP, les facteurs de correction de perturbation à profondeur zref dans le graphite ont été calculés pour le linac Radiation Dynamics du NPL à des énergies de 4-19 MeV. Ces résultats, combinés à ceux dans l'eau calculés par Zakikhani (2006), ont montré que seulement les facteurs de perturbation de l'eau par rapport au graphite des faisceaux de 4 MeV et 12 MeV, à 1,0080 ± 0,27 % et 1,0071 ± 0,28 % respectivement, étaient significativement différents de l'unité. Les facteurs de correction de perturbation dans l'eau et dans le graphite ont aussi été étudiés pour les linacs cliniques de Varian à 4-18 MeV. D'importants problèmes ont alors été soulevés, notamment des différences dans les résultats causés par des énergies de coupure de 1 keV par rapport à 10 keV ainsi que la question de savoir si la profondeur du point de mesure devrait prendre en compte l'épaisseur effective de la fenêtre d'entrée. Ces problèmes requièrent davantage d'études.

Les surfaces gauches sont très largement utilisées dans la modélisation d'objets. L'obtention de ces modèles se fait directement par usinage ou par réalisation d'un moule qui sera utilisé en fonderie ou en matriçage. Les logiciels de fabrication assistée par ordinateur ne proposent pas d'aide à l'utilisateur pour la planification des trajectoires. Les choix d'outils, de posage de la pièce dans l'espace de la machine et de stratégie sont souvent arbitraires et reposent sur des habitudes qui souvent conduisent à une faible efficacité. Nous nous proposons dans cette thèse, en vue d'augmenter la productivité, d'établir un critère permettant de justifier le choix de la géométrie de l'outil, du posage et de la stratégie associée. Des travaux de recherche ont prouvé l'efficacité des outils toriques par rapport aux outils sphériques en termes de taux d'enlèvement de matière. Cependant il a été montré que cette efficacité n'est avérée et maximale que pour une direction d'usinage bien précise qui est celle de la plus grande pente. La direction optimale d'utilisation des outils toriques variant sur toute la surface à usiner, des travaux plus récents ont proposé des méthodes de partitionnement de surface : la surface à usiner est découpée en zones qui sont chacune usinées suivant une direction optimale. La planification de trajectoires d'usinage des surfaces complexes se heurte aujourd'hui au problème du choix du nombre de zones lors du découpage de la surface à usiner : un découpage trop grossier ne permettra pas de garantir l'efficacité de l'utilisation d'un outil torique mais un découpage trop fin induira des temps de déplacement entre zones importants et des changements de direction fréquents qui forcent la machine à ralentir et ainsi pénaliseront la productivité. Une méthode de découpage minimal de la surface complexe garantissant l'efficacité d'un outil torique est donc développée et proposée dans ces travaux. Un coefficient d'efficacité permettant de quantifier l'intérêt de l'utilisation d'un outil torique par rapport à un outil sphérique est introduit puis une stratégie de découpage de la surface garantissant l'efficacité d'un outil torique en tout point usiné est établie. La méthode est ensuite étendue en prenant en compte dans un premier temps un posage optimal puis en modifiant le posage (sur une machine 5 axes utilisée en 3+2 axes) pour chaque zone considérée. De nombreuses simulations démontrent l'efficacité de la méthode qui a également été validée expérimentalement
Free form surfaces are widely used in object modeling. These models are obtained directly by machining or by making a mould that will be used in foundry or forging. Computer-aided manufacturing software does not provide user assistance for path planning. The choice of tools, the setup of the part in the machine space and the strategy are often arbitrary and based on habits that often lead to low efficiency. In this thesis, we propose, in order to increase productivity, to establish a criterion to justify the choice of tool geometry, setup and associated strategy. Research has proven the effectiveness of toroidal tools compared to spherical tools in terms of material removal rates. However, it has been shown that this efficiency is only proven and maximum for a specific machining direction, which is the one with the steepest direction. Since the optimal direction of use of toroidal tools varies over the entire surface to be machined, more recent work has proposed surface partitioning methods: the surface to be machined is divided into zones, each of which is machined in an optimal direction. The planning of machining paths for complex surfaces nowadays faces the problem of choosing the number of zones when cutting the surface to be machined: cutting too coarse will not guarantee the efficiency of using a toroidal tool, but cutting too thin will induce travel times between important zones and frequent changes in direction that force the machine to slow down and thus penalize productivity. A minimum cutting method for the free form surface guaranteeing the efficiency of a toroidal tool is therefore developed and proposed in this work. An efficiency coefficient allowing to quantify the interest of using a toroidal tool compared to a spherical tool is introduced and then a surface cutting strategy guaranteeing the efficiency of a toroidal tool at any point machined is established. The method is then extended by first taking into account an optimal setup and then modifying the setup (on a 5 axis machine used in 3+2 axes) for each area considered. Many simulations demonstrate the effectiveness of the method, which has also been experimentally validated

Thesis (MScEng (Civil Engineering))--Stellenbosch University, 2008.
The Southern African Institute of Steel Construction expressed concern with regard to the unit definition of the effective length factor, K, stipulated for compressive elements of parallel chord trusses in Clause 15 of SANS 10162-1:2005 - Limit state design of hot-rolled steelwork. The simplified method for truss design specified in the code assumes all compression members are pin-connected, which allows for greater design simplicity and reduces the amount of code interpretation required by the designer. In addition to this, Clause 15 requires the additional reduction in resistance of the first web compression members by a factor of 0.85. However, this approach may be considered overly conservative and in current design practice the effective length factor is often reduced to less than 1.0. This research investigates the effective length factor of web compression members in parallel chord trusses, by means of investigative structural analyses of representative trusses using ANGELINE and Prokon analytical programs, and by designing, constructing and testing six representative trusses, using current design practices. A comparative study of a number of different countries’ codified approaches to truss design is also included. The structural analyses revealed that in-plane buckling of the web compression members was the consistent mode of failure, however at a much greater applied load than the design load determined according to SANS 10162-1:2005. Contrary to the expected mode of failure, all six tests performed on the representative trusses exhibited elastic out-of-plane buckling, or strongaxis buckling, of the web compression members, but still at a much greater applied load than the design load. The unexpected out-of-plane buckling of the web members is due to the inplane stiffness of the end connections used. In order to stay true to current design practice, gusset plates and longitudinal welds were used to join the web members to the chords. The stiffness of the gusset plates therefore significantly reduced the effective length of the web compression members in-plane, but did not reduce the effective length out-of-plane. Despite the unanticipated behaviour of the tests performed, certain conclusions can still be drawn from the results. The unit definition of the effective length factor for in-plane buckling of web compression members is too conservative and a K factor of 0.8 is recommended. In addition to this an effective length factor for out-plane-buckling of web compression members of 1.1 is recommended for trusses with welded connections. The necessity of the reduction in resistance of 0.85 of the first web compression members requires further investigation. The most important conclusion to be drawn is that out-of-plane buckling of web compression members can be the dominant failure mode, which is not taken into consideration in current design practice.

This paper demonstrates an approach for passive alignment and assembly of link components for board-level very-short range optical interconnects. This interchip optical link is based on planar polymeric multimode waveguides and glassbased electro-optical transceivers. The main aim of the work is the investigation of assembly processes of link components in order to fulfill the tolerance requirements using passive alignment. The optical characterization in regard to the optical coupling between link components will define the tolerances for the alignment process. This optical analysis is based on measurements of spatial coupling characteristics. The influence of assembly tolerances on the coupling efficiency is investigated. Flip-chip assembly of electro-optical devices on the glass interposer and of the glass interposer on optical overlay is presented to prove the implementation of the concept.

This paper discusses the technology development for integration of parallel optical interconnects on board-level, including the active and passive optical components as well as the electrical integrated circuitry. The inter-chip link is based on planar polymeric optical multimode waveguides with integrated out-of-plane coupling optics and optical transceiver subassemblies based on glass interposer. Integration of polymeric waveguides on flexible substrates will be shown since the realization of an overlay optical substrate enhances the yield and testability of the final hybrid electrooptical printed circuit board (EOPCB). Realized on-board waveguides feature low insertion loss (minimum attenuation coefficient of below 0.1 dB/cm). For short planar waveguides (Lwaveguide = 9 cm) error free transmission (BER < 10-12) up to 30 Gbit/s was achieved. The development of glass interposer passive optical coupling structures for VCSEL-based short-distance links will be described.

Дисертаційна робота присвячена дослідженню закономірностей процесу концентрування водних розчинів малолетких рідин у стікаючій плівці випаровуванням в перехресний потік нейтрального газу і використанню результатів цих досліджень для створення нової конструкції концентратора та методики його розрахунку. Такий концентратор дозволяє проводити безвакуумне концентрування розчинів при температурі нижче температури їх кипіння, що, зважаючи на високі температури кипіння мололетких рідин, дає можливість знизити енерговитрати й відмовитися від дефіцитних видів палива, що використовується для нагрівання розчину. Відповідно до мети та поставлених задач, дослідження мали характер комплексних, оскільки були використані як теоретичні так експериментальні методи, які знайшли своє застосування у концентруванні водних розчинів. Теоретичні дослідження проводили використовуючи метод математичного моделювання, який полягав у формулюванні спрощених фізичних уявлень про процеси, що вивчаються, і опис їх системою диференційних та інтегральних рівнянь. Розрахунки, пов'язані з моделюванням і обробкою експериментальних даних проводили за допомогою програмного забезпечення Microsoft Excel, Mathcad. У дисертації наведені результати моделювання гідродинаміки і тепломасоперенесення стікаючої плівки індивідуальної (однокомпонентної) рідини, що випаровується в перехресний потік нейтрального газу з використанням розробленої математичної моделі. Ці результати показали закономірності зміни товщини, швидкості стікання і температури плівки за її довжиною, а також температури газу над плівкою. Встановлено, що інтенсивність випаровування рідини з плівки при її перехресному напрямку руху щодо газового потоку більше, ніж при прямоточному напрямку і може перевищувати інтенсивність випаровування при протиточному напрямку. Температура плівки рідини, що випаровується в перехресний потік нейтрального газу, при віддаленні від її початкового перерізу досягає усталеного значення, а при подальшому збільшенні відстані від цього перерізу рідина повністю випаровується. Розроблено алгоритм розрахунку відстаней, на яких відбуваються ці явища. Температура газу над плівкою за довжиною плівки змінюється несуттєво, але за своїм характером ця зміна відповідає зміні температурі плівки, і також досягає усталеного значення. В ході експериментальних досліджень використовували методи фізичного моделювання із застосуванням теорії подібності, статистичної обробки експериментальних даних. Вхідні та вихідні параметри досліджуваних процесів на експериментальній установці визначали манометричним, термометричним і об'ємним методами вимірювання. А концентрацію водних розчинів гліцерину, який використовувався в якості модельної рідини, вимірювали ареометричним і рефрактометричним методами. На підставі експериментального дослідження тепломасоперенесення в стікаючій плівці води, що випаровується в перехресний потік повітря, встановлені значення коефіцієнта тепловіддачі від поверхні до стікаючої з неї плівки, а також коефіцієнтів тепло – і масовіддачі від плівки до повітряного потоку. Показано, що залежності коефіцієнтів тепло – і масовіддачі від початкового потоку рідини проходять через мінімум, відповідний 𝑅𝑒ж≈500, що свідчить про перехід від ламінарного режиму течії плівки до турбулентного в умовах, що розглядаються. Встановлено залежність цих коефіцієнтів від параметрів процесу тепломасоперенесення для обох режимів. На підставі математичної обробки експериментальних даних були отримані емпіричні рівняння для їх розрахунку. Отримані результати математичного моделювання та експериментального дослідження випаровування індивідуальної рідини зі стікаючої її плівки стали основою для розробки математичної моделі і дослідження процесу концентрування водних розчинів малолетких рідин в стікаючій плівці випаровуванням в перехресний потік нейтрального газу. За допомогою цієї моделі встановлено закономірності зміни складу розчину за довжиною плівки та інтенсивності процесу концентрування. Показано, що концентрація розчину на початку плівки змінюється лінійно, потім відбувається її різкий підйом, що триває до повного випаровування води. Такий характер зміни концентрації розчину за довжиною плівки пов'язаний з розподілом температури плівки. Різкий підйом концентрації відповідає усталеному значенню температури. Встановлено, що інтенсивність процесів концентрування зростає зі зменшенням початкового потоку розчину і його початкової концентрації, а також зі збільшенням початкової температури розчину, температури поверхні стінки, на якій стікає плівка й початкової температури повітря, що надходить в простір над плівкою. Зі збільшенням швидкості повітря інтенсивність концентрування падає. Проведено експериментальне дослідження процесу концентрування водних розчинів гліцерину в їх стікаючій плівці в умовах випаровування в потік повітря, в результаті якого визначені коефіцієнти тепло – і масовіддачі, що являються параметрами розробленої математичної моделі. Встановлено, що в дослідженому діапазоні зміни параметрів процесу для низько концентрованих розчинів гліцерину, як і для води, характерний перехід від ламінарного режиму стікання плівки до турбулентного, для розчинів з підвищеною концентрацією гліцерину такий перехід відсутній і плівка стікає тільки в ламінарному режимі. У дисертації на основі експериментальних досліджень показано прояв капілярних ефектів за умов стіканні плівки рідини, що випаровується в перехресний газовий потік, який виражається зменшенням ширини плівки. Також встановлені закономірності цього зменшення для плівок води й водних розчинів гліцерину залежно від параметрів процесу стікання. Для води і водних розчинів гліцерину така зміна ширини плівки може досягати 50-80%. Найбільший вплив на зменшення ширини плівки за таких умов дають початковий потік рідини та температура поверхні стікання. Для коригування поверхні випаровування плівки, визначеної на основі технологічного розрахунку, була введена величина ширини середньої поверхні випаровування плівки. Результатами експериментального дослідження впливу параметрів процесу стікання плівки води й водних розчинів гліцерину на ширину середньої поверхні випаровування стали узагальнені емпіричні закономірності, що пов'язують коригувальний коефіцієнт з основними параметрами процесу стікання. На основі проведених в дисертаційній роботі теоретичних і експериментальних досліджень закономірностей стікання і тепломасоперенесення в плівці рідини, а також моделювання процесу концентрування водних розчинів малолетких рідин в стікаючій плівці розроблена нова конструкція і методика розрахунку плівкового концентратора таких розчинів. Конструкція заснована на використанні плоско–паралельної (пластинчастої) насадки, що дозволяє забезпечити перехресну взаємодію стікаючої плівки рідини з газовим потоком. Елементи насадки (пластини) мають внутрішні порожнини, де проходить теплоносій, що нагріває плівку розчину, яка стікає з її зовнішньої поверхні. Методика розрахунку випробувана на конкретному прикладі розрахунку концентратора водного розчину гліцерину. Її апробація показала, що для підвищення концентрації цього розчину від 6 до 30% (мас.) з продуктивністю в 2,0 т/год необхідна робоча висота плоско – паралельної насадки рівна 1,62 м. Розроблену методику розрахунку такого апарату та ескізний проект на концентратор прийнятий Державним науково – дослідним інститутом хімічних продуктів у розробку директивного технологічного процесу та проектування фази регенерації відпрацьованої кислотної суміші виробництва нітратів целюлози. Результати дисертаційних досліджень впроваджені в учбовий процес при викладанні дисциплін "Процеси і апарати хімічних виробництв" та "Технологія виробництва спеціальних високомолекулярних сполук" на кафедрі хімічної технології високомолекулярних сполук Шосткинського інституту СумДУ.
The thesis is devoted to the study of the regularities of the process of concentration of aqueous solutions of some low–volatile liquids in a flowing diaper by evaporation into a cross flow of neutral gas and the use of the results to create a new kind of the concentrator. Such kind of a concentrator makes possible vacuum–free concentration of solutions at temperatures below their boiling point, which, due to the high boiling points of volatile liquids, helps to reduce energy consumption and to avoid the scarce types of fuel used while heating the solution. The thesis presents the results of modeling the hydrodynamics and heat and mass transferring of a flowing film of an individual (of one component) liquid evaporating into a cross flow of a neutral gas using the created mathematical model. The results demonstrate the regularities of changes in the thickness, flow rate and temperature of the film along its length, as well as the temperature of the gas above the film. It was found that the intensity of evaporation of liquid from the film during its cross–interaction with the gas flow is higher than during direct–flow interaction and can exceed the rate of evaporation during counter current interaction. The temperature of a liquid film evaporating into a cross flow of a neutral gas, with distance from its initial cross section, reaches an equilibrium value, and with a further increasing the distance from this section, the liquid evaporates completely. There has been developed an algorithm for calculating the distances at which these phenomena appear. The temperature of the gas above the film along the length of the film changes insignificantly, but by its natural characteristics this change is associated with the temperature of the film and reaches an equilibrium value, in addition. On the basis of an experimental study of heat and mass transfer in a flowing film of water evaporating into a cross flow of air, the values of the heat transfer coefficient from the surface to the film flowing along it, as well as the coefficients of heat and mass transfer from the film to the air flow, have been established. The dependence of these coefficients on the parameters of the heat and mass transfer process showed the presence of a transition from the laminar mode of film flow to the turbulent one at the value of the number 𝑅𝑒ж≈500. Mathematical processing of the experimental data made it possible to obtain empirical equations for calculating the heat and mass transfer coefficients. The obtained results of mathematical modeling and experimental study of the evaporation of an individual liquid from its flowing down film became the basis for the development of a mathematical model and study of the process of concentration of aqueous solutions of some low–volatile liquids in a flowing film by evaporation into a cross flow of neutral gas. Using this model, the regularities of changes in the composition of the solution along the length of the film and the intensity of the concentration process were established. It is shown that the concentration of the solution at the beginning of the film changes linearly, then there is a abrupt rise, continuing until the complete evaporation of water. This kind of a change in the concentration of the solution along the length of the film is associated with the temperature distribution of the film. The abrupt rise of concentration corresponds to the state temperature value. An experimental study of the process of concentration of aqueous solutions of glycerin in their flowing film in the conditions of evaporation into an air stream was carried out, as a result of which the heat and mass transfer coefficients were determined, which are the parameters of the developed mathematical model. It was found that, in the investigated range of variation of the process parameters, for low–concentration solutions of glycerol, as well as for water, it is common to observe the transition from a laminar mode of film flow to a turbulent one, for solutions with an increased concentration of glycerol, such a transition is absent and the film flows down only in a laminar mode. The thesis presents experimental data on a decrease in the width of a liquid film flowing down a heated flat surface, associated with capillary effects. For water and aqueous solutions of glycerin, such a change in the width of the film can reach 50-80%. The natural characteristic of the change in the width of the film along its length and the obtained empirical dependences for its assessment are established. On the basis of the results obtained in the thesis, the study of the process of concentrating aqueous solutions of some low–volatile liquids, a new design and method for calculating a film concentrator have been developed. The design is based on the use of a plane–parallel (lamellar) packing, which makes possible a cross–flow interaction. The elements (plates) of the packing have internal cavities through which the coolant passes, heating the solution film flowing down their outer surface. The calculation technique was tested on specific parameters of the concentration process.

碩士
國立臺灣科技大學
機械工程系
107
The flow characteristics of two parallel plane jets were experimentally studied. The widths and lengths of the jet exits were 4 mm and 145 mm, respectively. The ratios of the spacing between the two neighboring jets to the width of the jet exits were 3, 5, 8, 10, and 15. According to the smoke-flow visualization results, two characteristic flow modes, combination before vortex breakup (CBVB) and combination after vortex breakup (CAVB), were identified in the domain of non-dimensional jet spacing and jet Reynolds number. Coherent structures evolved in the shear layers of the jets issued from the jet exits and expanded laterally as the jets travelled downstream. The CBVB mode appeared at small non-dimensional jet spacing. The jet columns inclined slightly toward the centerline due to the slightly low pressure existing between the neighboring jets in the near field. The shear-layer coherent structures merged together, broke up into small eddies, then combined into a single jet to evolve to downstream area. The CAVB mode appeared at large non-dimensional jet spacing. The neighboring jets combined into a single jet to evolve to downstream area first, then the shear-layer coherent structures merged together and broke up into small eddies. The PIV measured velocity fields showed a recirculation region consisted of two counter-rotating vortices existing between the jets near the jet exits. The apex of the recirculation region was a four-way saddle which was a merge point (MP) of the two parallel plane jets. Around the centerline upstream the MP, the flow velocities were reversed. Around the centerline downstream the MP the flow velocity pointed downstream. However, the lateral velocity profiles presented a deficit around the centerline. As the lateral velocity profiles evolved downstream, the velocity deficits around the centerline became smaller and smaller, and finally attained a local maximum at an axial distance downstream the MP. The location where the centerline velocity became the maximum of the lateral velocity profile was termed the combined point (CP). The velocity distribution in axial and lateral directions, characteristic flow regimes, axial lengths of the MP and CP were presented, analyzed, and discussed.

碩士
高雄醫學大學
牙醫學研究所
99
Background: Orientation of the occlusal plane is one of the most important clinical procedures in prosthodontic rehabilitation of edentulous patients. Because of its effect on aesthetics, function and denture stability, it should be reconstructed as identical as possible to the occlusal plane of missing natural teeth. The use of the ala-tragus line to orient the occlusal plane is advocated by some authors. However, there is some controversy on the exact points of references of the ala-tragus line, since some researchers believe in using the lower border of the tragus, others believe in using the middle part of the tragus, and still others believe in using the upper part. In the past, cephalometric and photographic analysis has been used to investigate the relationship between the natural occlusal plane and anatomical structure in the skull. At present, this study aims at determining the most reliable ala-tragus line as a guide for the orientation of the occlusal plane by using cone-beam computed tomography (CBCT). Materials and Methods: A total of fifty-eight young adults (22 females and 36 males) with complete natural dentition were selected. Exclusion criteria included history of major trauma to the face, nose surgery, craniomandibular disorder syndrome, or previous orthodontic treatment. The metal indicators were attached to anterior and posterior reference points. The occlusal planes were determined by mesio-incisal angle of the maxillary central incisors and mesio-buccal cusp tip of the maxillary first or second molar. A 3D CBCT images was taken for each patient. The X, Y, and Z 3D space coordinates of each points would be located and obtained, then three points formed a plane. The angles between those planes were measured, and statistical analysis were carried out. Results: The measurement results are presented by mean values and standard deviations. The angle between the occlusal plane and Camper’s plane had the lowest mean value in the angle formed with Camp. 3L-Occ. 2 (7.43±4.88°) and the highest mean value in the angle formed with Camp. 1R-Occ. 1 (15.56±7.64°). And the angles between Camp. 3-Occ. 1/2 group had lower value than other groups. The differences between the planes in relation to the occlusal planes were found to be very highly significant (p &lt; 0.001). It means no absolutely parallelism exists between the occlusal plane and the ala-tragus line. Conclusion: According to the result of the present study, there is no parallelism between the occlusal plane with two different posterior reference points and the ala-tragus line with three different posterior ends. The average angle between the occlusal plane connecting mesio-incisal angle of maxillary central incisors with mesio-buccal cusp tip of maxillary second molar and the Camper’s plane connecting the inferior border of ala with inferior border of tragus had the lowest mean angle (7.43～7.86°). This value is higher than the literature reports by other researchers. Within the limitations of this study, it may be summarized that the inferior border of the tragus with the inferior border of the ala of the nose was more accurate in orienting the occlusal plane than others.

碩士
國立中央大學
物理學系
102
The first Proton Therapy Center in Taiwan will be soon in operation. The superior quality of the depth-dose distribution of protons than electrons or photons to the target volume is well known. Proton therapy can reduce the radiation dose to normal tissue surrounding the tumor due to high-energy proton beam energy can be adjusted so that after it penetrates the body, it stops in the tumor, and will not continue to penetrate to damage the rear of the organ. However, protons generate more ion pairs in gas filled ionization chamber than electrons or photons, therefore, higher current density in detector. From BOAG theory, recombination effects depend on the electric field applied, the gas width of electrodes and the current density. The purpose of this study is to investigate the recombination effects with parallel plate ionization chamber. Pad Ionization Chambers were used to study the recombination effect. The experiment was done at Institute of Nuclear Energy Research with 30 MeV protons. We set the experimental steps: (1) two gas gap: 3mm and 6mm, respectively (2) four beam current intensity (1, 5, 10 and 15 nA) (3) scanning electric field between parallel plates (for 3mm, from 100V to 1500V in step of 100 volts; for 6mm, from 200V to 3000V in step of 200 volts). Collection efficiency means the relations between its ionization current and collection by pad ion chamber due to recombination by ions. Using Faraday cup timely monitoring of their beam current changes, and it measured by subtracting the amount of current material to stop the current correction ionization chamber current actual incident, this amendment before the experiment is an important step before analyzing. Finally, we verified BOAG theory and compliance with General Recombination (Volume recombination) effects as the dominate ingredient under the experimental conditions. In proper operating voltage region; the larger E field, the smaller electrode spacing and the lower current intensity, the recombination efficiency is less than 0.1%. In proton therapy, we can ignore this recombination phenomenon; the proton beam current means collection ionization current by ion chamber.

碩士
國立臺灣科技大學
機械工程系
107
In this study, the flow pattern and flow field characteristics of two-dimensional jet issuing from two adjacent, parallel with constant velocity at different intervals are analyzed by 2D-CFD. The widths of the jet exits were 4 mm. The ratios of the spacing between the two jets to the width of the jet exits were 5, 10, and 15. The Reynold number range were between 200 and 1600. The CFD results show that there is a saddle point in the recirculation zone between the two jets. The saddle points have similar-shaped structures but are not affected by the different Reynold number and the ratios of the spacing between the two jets to the width of the jet exits. The jets approach each other in the converging region, and velocity is rise. When the two jets are no longer approached each other and advance in parallel, the velocity are decreased. The merge point moves downstream as the nozzle exit spacing increases, but is not affected by the Reynolds number. The combined point moves downstream as the nozzle exit spacing increases or the Reynolds number increases. The ratios of the combined jet velocity and the outlet velocity are the same between Reynolds number 200 and 1200, but are different between Reynolds number 1400 and 1600. In converging region, the vorticity between two jet approaches zero. At the same two jets to the width of the jet exits, the overall vorticity change of Reynolds number between 1400 and 1600 is higher than the Reynolds number of 200 to 1200.

Thesis (M.S.)--University of Wisconsin--Madison, 1995.
Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 160-170).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1988.
Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 70-72).

A two-dimensional model for predicting the rate of radiation heat transfer for the interior of an industrial furnace is described. The model is two-dimensional due to the assumptions of the heat source as an infinite radiating plane and the heat sink as rows of parallel tubes that are both infinite in length and in number. A refractory back wall, located behind the tube rows, is also included in some of the model configurations. The optical properties for the heat source, heat sink, and refractory back wall are simplified by assuming the "black-body" case: all are treated as perfect absorbers and emitters of radiation. This assumption allows three different solution techniques-a graphical, crossed-string, and numerical method-to be used in solving for the radiant transfer rate. The numerical method, an innovative Monte Carlo technique, is the one employed in this study. Hottel used a graphical technique to solve the furnace model for a two row configuration in which the tubes are arranged on equilateral triangular centers. His results, along with those produced by the crossed-string method, are used in this work to validate the numerical technique. Having been validated, the numerical method was then employed to extend Hottel's work by adding more tube rows to the original equilateral triangular configuration and by generalizing the results to isosceles arrangements. Findings of this investigation are summarized in a table that lists the direct view factors for a ten tube row configuration arranged in an equilateral triangular array. Values from this table can be used to solve the transfer rate problem for twenty different cases by assuming a nonconducting refractory back wall. Results for twelve cases are represented graphically in this document The results are used to demonstrate the importance of a refractory back wall on overall radiation absorption. Examinations of the two row and five row cases for an isosceles triangular array indicate that the tabular values can be applied to any isosceles arrangement if the ratio of row separation distance to tube center-to-center distance is 0.7 or greater.
Graduation date: 1995

碩士
景文科技大學
電腦與通訊研究所
97
The thesis mainly discuss a kind of antenna structure parallel to non-ideal ground plane, take notebook antenna as an examples, A notebook antenna suffer from non-ideal ground plane and being parallel to the LCD monitor on the ground; the radiation efficiency of the antenna decreases obviously. This thesis propose three kinds of antenna structures,3D-PIFA,3D-Tab monopole and the compound structure. The compound structure combines the benefits of 3D-PIFA and 3D-Tab monopole structure to overcome the effects of complex environments in notebook. Consequently, better the antenna efficiency and enough BW for WWAN frequency range (824~2170MHz) can be achieved through compound structure. Design procedures and variation of each parameter relative to antenna performance are explained in detail in this thesis.

博士
國立臺灣大學
化學工程學研究所
91
Abstract Driven by applying an electrical potential, temperature, or solute concentration gradient, the transport of colloidal particles in a continuous medium is known as the “phoretic motion”. In this work, a boundary collocation method and a reflection method are utilized to calculate the various phoretic velocities of small spherical particles migrating parallel to one or two plane walls. First, in chapter 2, the quasisteady diffusiophoretic motion of a spherical particle in a fluid solution of a nonionic solute located between two infinite parallel plane walls is studied in the absence of fluid inertia and solute convection. The imposed solute concentration gradient is constant and parallel to the two plane walls, which may be either impermeable to the solute molecules or prescribed with the far-field concentration distribution. The particle-solute interaction layer at the particle surface is assumed to be thin relative to the particle radius and to the particle-wall gap widths, but the polarization effect of the diffuse solute in the thin interfacial layer caused by the strong adsorption of the solute is incorporated. The presence of the neighboring walls causes two basic effects on the particle velocity: first, the local solute concentration gradient on the particle surface is enhanced or reduced by the walls, thereby speeding up or slowing down the particle; secondly, the walls increase viscous retardation of the moving particle. Numerical results for the diffusiophoretic velocity of the particle relative to that under identical conditions in an unbounded fluid solution are presented for various values of the relaxation parameter of the particle as well as the relative separation distances between the particle and the two plates. For the special case of diffusiophoretic motions of a spherical particle parallel to a single plate and on the central plane of a slit, the collocation results agree well with the approximate analytical solutions obtained by using a method of reflections. The presence of the lateral walls can reduce or enhance the particle velocity, depending on the surface properties of the particle, the relative particle-wall separation distances, and the solutal boundary condition at the walls. A theoretical study is presented in chapter 3 for the quasisteady osmophoretic motion of a spherical vesicle in a solution located between two infinite parallel plane walls in the limit of negligible Reynolds and Peclet numbers. The applied solute concentration gradient is uniform and parallel to the two plane walls, which may be either impermeable to the solute molecules or prescribed with the far-field concentration distribution. The presence of the neighboring walls causes two basic effects on the vesicle velocity: first, the local concentrations on both sides of the vesicle surface are altered by the walls, thereby speeding up or slowing down the vesicle; secondly, the walls enhance the viscous interaction effect on the moving vesicle. Numerical results for the osmophoretic velocity of the vesicle relative to that under identical conditions in an unbounded solution are presented for various values of the relevant properties of the vesicle as well as the relative separation distances between the vesicle and the two plates. For the special case of osmophoretic motions of a spherical vesicle parallel to a single plate and on the central plane of a slit, the collocation results agree well with the approximate analytical solutions obtained by using a method of reflections. The presence of the lateral walls can reduce or enhance the vesicle velocity, depending upon the relevant properties of the vesicle, the relative vesicle-wall separation distances, and the solutal boundary condition at the walls. In chapter 4, the steady thermocapillary migration of a fluid droplet located between two infinite parallel plane walls is examined in the absence of fluid inertia and thermal convection. The imposed temperature gradient is constant and parallel to the two plates, and the droplet is assumed to retain a spherical shape. The plane walls may be either insulated or prescribed with the far-field temperature distribution. The presence of the neighboring walls causes two basic effects on the droplet velocity: first, the local temperature gradient on the droplet surface is enhanced or reduced by the walls, thereby speeding up or slowing down the droplet; secondly, the walls increase viscous retardation of the moving droplet. Numerical results for the thermocapillary migration velocity of the droplet relative to that under identical conditions in an unbounded medium are presented for various values of the relative viscosity and thermal conductivity of the droplet as well as the relative separation distances between the droplet and the two plates. For the special cases of thermocapillary motions of a spherical droplet parallel to a single plate and on the central plane of a slit, the collocation results agree well with the approximate analytical solutions obtained by using a method of reflections. The presence of the lateral walls can reduce or enhance the droplet velocity, depending upon the relative transport properties of the droplet, the relative droplet-wall separation distances, and the thermal boundary condition at the walls. In chapter 5, the quasisteady thermophoretic motion of a spherical particle in a gaseous medium located in an arbitrary position between two infinite parallel plane walls is studied in the absence of fluid inertia and thermal convection. The Knudsen number is assumed to be small so that the fluid flow is described by a continuum model with a temperature jump, a thermal slip, and a frictional slip at the particle surface. The imposed temperature gradient is constant and parallel to the two plane walls, which may be either insulated or prescribed with the far-field temperature distribution. The presence of the neighboring walls causes two basic effects on the particle velocity: first, the local temperature gradient on the particle surface is enhanced or reduced by the walls, thereby speeding up or slowing down the particle; secondly, the walls increase viscous retardation of the moving particle. Numerical results for the thermophoretic velocity of the particle relative to that under identical conditions in an unbounded gaseous medium are presented for various values of the relative thermal conductivity and surface properties of the particle as well as the relative separation distances between the particle and the two plates. For the special case of thermophoretic motions of a spherical particle parallel to a single plate and on the central plane of a slit, the collocation results agree well with the approximate analytical solutions obtained by using a method of reflections. The presence of the lateral walls can reduce or enhance the particle velocity, depending upon the relative thermal conductivity and surface properties of the particle, the relative particle-wall separation distances, and the thermal boundary condition at the walls. Finally, the four phoretic motions considered in chapters 2-5 are simply compared.

This work describes the design and measurement of a compact bidirectional ultrawideband (UWB) modified equiangular spiral antenna with an integrated feed internally matched to a 50-Ohm microstrip transmission line. A UWB transition from microstrip to double-sided parallel-strip line (DSPSL) soldered to a short (1.14 mm) twin-line transmission line feeds the spiral. The currents on the feed travel in a direction approximately perpendicular to the direction of the currents on the spiral at the points where the feed passes the spiral in close proximity (0.57 mm). Holes were etched from the metal arms of the spiral to reduce the impedance mismatch caused by coupling between the transmission line feed and the spiral. This work also describes a low-loss back-to-back transition from coaxial line to DSPSL, an in-phase connectorized 3 dB DSPSL power divider made using three of those transitions, a 2:1 in-phase DSPSL power divider, a 3:1 in-phase DSPSL power divider, a radial dipole fed by DSPSL, an array of those dipoles utilizing the various power dividers, and a UWB circular monopole antenna fed by DSPSL. Measured and simulated results show good agreement for the designed antennas and circuits.

碩士
國立中山大學
物理學系研究所
99
The contactless electroreflectance（CER） spectra of ZnO bulk has been measured at 300K. It was observed the difference between the CER spectra by using the polarization E of probe light perpendicular ( E⊥c) and parallel ( E∥c) to the c-axis of the m-plane ZnO. In addition, a mercury lamp was focused on the sample to reduce its strength of electric field. It was observed that the CER spectrum was blue-shifted with Hg lamp being on. Hence, the observed features were attributed to excitonic transitions. The experimental spectra were fitted by Lorentzian lineshapes. The energies of the A ( B）, B（A）, and C excitonic transitions were determined as 3.329eV, 3.343eV and 3.387eV, respectively.