Design of a Self-Adaptive Down-Hole Layered Steam Injector and Its Application

Layered steam injection, widely used in Liaohe Oilfield at present, is an effective recovery technique to heavy oil reserves. Which makes the steam front-peak push forward uniformly, the amount of steam injection be assigned rationally, and the effect of injection steam be obtained as expected. To maintain a fixed ratio of layered steam injection and solve the problem of nonadjustable hole diameter with the change of layer pressure in the existing injectors, a new method is proposed in this paper to design layered steam injectors based on the dynamic balance theory According to gas-liquid two-phase flow theory and heat transfer theory, the energy equation and the heat conduction equation in boreholes are developed. By analyzing the energy equilibrium of water-steam passing through the injector hole, we find an expression to describe the relation between the cross-sectional area of injector hole and the layer pressure. With this expression, we provide a new set of calculation methods and write the corresponding computer program to design and calculate the main parameters of a steam injector. The actual measurement data show that the theoretically calculated results are accurate, the software runs reliably, and they provide the design of self-adjustable layered steam injectors with the theoretical foundation.

Estudo físico-químico de copoliéteres por viscosimetria

A viscosimetria é um procedimento experimental simples e pouco oneroso, que pode fornecer informações valiosas sobre o volume hidrodinâmico e a conformação de macromoléculas em solução, num determinado solvente, em uma dada temperatura. Os parâmetros viscosimétricos podem ser matematicamente calculados por extrapolação gráfica, cuja execução experimental é mais demorada. Em contrapartida, é possível que a determinação seja feita por um único ponto. Neste trabalho, os dois métodos de cálculo, empregando uma série de seis equações: Huggins, Kraemer e Schulz-Blaschke, por extrapolação gráfica, e Schulz-Blaschke, Solomon-Ciuta e Deb-Chanterjee por um único ponto, foram utilizados em soluções de poli(glicol propilênico) (PPG) e copolímeros em bloco à base de poli(glicol propilênico) e poli(glicol etilênico) (EG-b-PG), com diferentes teores de poli(glicol etilênico), tendo isopropanol, tetra-hidrofurano (THF) e tolueno como solventes puros, além das misturas em proporções iguais de THF/ isopropanol e THF/ tolueno, a 25C. Os valores de viscosidade intrínseca e de algumas constantes indicaram que os solventes puros e as misturas se apresentaram no limite entre o bom e o mau solvente. Verificou-se também que o método de cálculo por um único ponto foi válido, especialmente quando a equação de Schulz-Blaschke foi empregada, apresentando um baixo percentual de erro sendo possível assim reduzir o tempo de análise para a maioria dos sistemas estudados

Copolímeros à base de estireno e anidrido maleico: caracterização e estudo viscosimétrico

Copolímeros à base de estireno e anidrido maleico (SMA) são materiais sintéticos comercialmente disponíveis, obtidos pela reação dos dois monômeros citados em diferentes proporções, resultando em materiais versáteis, e disponíveis em diferentes graus de massas e porcentagens molares de anidrido maleico. São considerados polímeros funcionais devido à reatividade do grupamento anidrido maleico presente na cadeia polimérica. Por este motivo, esses materiais possuem vasta gama de aplicações, e elevada importância em diversas áreas, principalmente por terem baixa toxicidade, boa resistência térmica e boa estabilidade dimensional. Dessa forma, para melhor aplicação desses copolímeros, é muito importante o conhecimento dos parâmetros relativos ao seu comportamento em solução. A viscosimetria, em especial, é um método simples, útil e apropriado para fornecer essas informações. Os parâmetros viscosimétricos podem ser matematicamente calculados por extrapolação gráfica, entretanto a geração dos dados experimentais é mais demorada. Em contrapartida, é possível que a determinação experimental seja feita de forma mais rápida, por um único ponto, procedimento esse que desperta tanto o interesse acadêmico quanto o industrial. Neste trabalho, foram empregados os dois métodos de cálculo, utilizando solventes puros, misturas de solventes e três amostras de copolímeros à base de SMA. As determinações foram conduzidas a 40C. Os copolímeros utilizados possuiam teores de anidrido maleico de 50%, 45% e 40%, sendo os dois últimos esterificados com butil-metil-éster e sec-butil-metil-éster, respectivamente. Os solventes utilizados foram: N-metil-pirrolidona (NMP), tetrahidrofurano (THF) e suas respectivas misturas 1:1 com metil-etil-cetona (MEK), ou seja, (NMP:MEK) e THF:MEK, sendo a MEK um não solvente para o copolímero não esterificado. As equações utilizadas para extrapolação gráfica foram as de Huggins, Kraemer e Schulz-Blaschke. As equações empregadas em um único ponto foram as de Solomon-Ciuta, Deb-Chanterjee e novamente Schulz-Blaschke. Os resultados obtidos foram comparados e avaliou-se a possibilidade da utilização do método mais rápido, por um único ponto, para os sistemas estudados através dos desvios percentuais tendo como padrão os resultados da equação de Huggins. A equação de Deb-Chanterjee foi a mais adequada aos sistemas em NMP, que foi também o melhor solvente para as amostras. Os resultados obtidos na mistura NMP:MEK sugeriram que a viscosimetria pode ter sido um método sensível às pequenas diferenças estruturais entre os grupos pendentes nas amostras esterificadas. Paralelamente, realizou-se análises de espectroscopia na região do infravermelho (FTIR), análise termogravimétrica (TGA) e ensaios dinâmico-mecânicos (DMA) para a caracterização estrutural e térmica das amostras. Somente os resultados obtidos a partir de DMA indicaram diferenças entre as amostras esterificadas

Dimensionamento e análise numérica de pisos industriais de concreto.

Os pisos industriais devem atender aos critérios de segurança, funcionalidade e durabilidade das estruturas de concreto. A fim de analisar o desempenho de placas de concreto apoiadas sobre base elástica quando submetidas a ações diretas e indiretas, foram elaborados diversos modelos analíticos e empíricos. Com o avanço tecnológico e o advento de softwares desenvolvidos através de processos numéricos como o método dos elementos finitos (MEF), a aplicação desses modelos foi facilitada. Este trabalho aborda os métodos de cálculo existentes e utilizados na execução dos projetos estruturais de pisos industriais de concreto.

A new apparatus for modelling excavations

Underground space is commonly exploited both to maximise the utility of costly land in urban development and to reduce the vertical load acting on the ground. Deep excavations are carried out to construct various types of underground infrastructure such as deep basements, subways and service tunnels. Although the soil response to excavation is known in principle, designers lack practical calculation methods for predicting both short- and long-term ground movements. As the understanding of how soil behaves around an excavation in both the short and long term is insufficient and usually empirical, the judgements used in design are also empirical and serious accidents are common. To gain a better understanding of the mechanisms involved in soil excavation, a new apparatus for the centrifuge model testing of deep excavations in soft clay has been developed. This apparatus simulates the field construction sequence of a multi-propped retaining wall during centrifuge flight. A comparison is given between the new technique and the previously used method of draining heavy fluid to simulate excavation in a centrifuge model. The new system has the benefit of giving the correct initial ground conditions before excavation and the proper earth pressure distribution on the retaining structures during excavation, whereas heavy fluid only gives an earth pressure coefficient of unity and is unable to capture any changes in the earth pressure coefficient of soil inside the zone of excavation, for example owing to wall movements. Settlements of the ground surface, changes in pore water pressure, variations in earth pressure, prop forces and bending moments in the retaining wall are all monitored during excavation. Furthermore, digital images taken of a cross-section during the test are analysed using particle image velocimetry to illustrate ground deformation and soil-structure interaction mechanisms. The significance of these observations is discussed.

Development of a new apparatus for modeling deep excavation related problems in geotechnical centrifuge

Underground space is commonly exploited both to maximise the utility of costly land in urban development and to reduce the vertical load acting on the ground. Deep excavations are carried out to construct various types of underground infrastructure such as deep basements, subways and service tunnels. Although the soil response to excavation is known in principle, designers lack practical calculation methods for predicting both short- and long-term ground movements. As the understanding of how soil behaves around an excavation in both the short and long term is insufficient and usually empirical, the judgements used in design are also empirical and serious accidents are common. To gain a better understanding of the mechanisms involved in soil excavation, a new apparatus for the centrifuge model testing of deep excavations in soft clay has been developed. This apparatus simulates the field construction sequence of a multi-propped retaining wall during centrifuge flight. A comparison is given between the new technique and the previously used method of draining heavy fluid to simulate excavation in a centrifuge model. The new system has the benefit of giving the correct initial ground conditions before excavation and the proper earth pressure distribution on the retaining structures during excavation, whereas heavy fluid only gives an earth pressure coefficient of unity and is unable to capture any changes in the earth pressure coefficient of soil inside the zone of excavation, for example owing to wall movements. Settlements of the ground surface, changes in pore water pressure, variations in earth pressure, prop forces and bending moments in the retaining wall are all monitored during excavation. Furthermore, digital images taken of a cross-section during the test are analysed using particle image velocimetry to illustrate ground deformation and soil–structure interaction mechanisms. The significance of these observations is discussed.

Quantum Mechanical Study on Tunnelling and Ballistic Transport of Nanometer Si MOSFETs

Using self-consistent calculations of million-atom Schrodinger-Poisson equations, we investigate the I-V characteristics of tunnelling and ballistic transport of nanometer metal oxide semiconductor field effect transistors (MOSFET) based on a full 3-D quantum mechanical simulation under nonequilibtium condition. Atomistic empirical pseudopotentials are used to describe the device Hamiltonian and the underlying bulk band structure. We find that the ballistic transport dominates the I-V characteristics, whereas the effects of tunnelling cannot be neglected with the maximal value up to 0.8mA/mu m when the channel length of MOSFET scales down to 25 nm. The effects of tunnelling transport lower the threshold voltage V-t. The ballistic current based on fully 3-D quantum mechanical simulation is relatively large and has small on-off ratio compared with results derived from the calculation methods of Luo et al.

Design of a fibre-optic disc accelerometer: theory and experiment

Mechanical principles of fibre-optic disc accelerometers (FODA) different from those assumed in previous calculation methods are presented. An FODA with a high sensitivity of 82 rad/ g and a resonance frequency of 360 Hz is designed and tested. In this system, the minimum measurable demodulation phase of the phase-generated carrier (PGC) is 10(-5) rad, and the minimum acceleration reaches 120 ng theoretically. This kind of FODA, with its high responsivity, all-optic-fibre configuration, small size, light weight and stiff shell housing, ensures effective performance in practice.

Comparative study for colloidal quantum dot conduction band state calculations

By comparing the results of some well-controlled calculation methods, we analyze the relative importance of bulk band structure, multi-bulk-band coupling, and boundary conditions in determining colloidal quantum dot conduction band eigenenergies. We find that while the bulk band structure and correct boundary conditions are important, the effects of multi-bulk-band coupling are small.

Computer-aided design of PV/wind hybrid system

A complete set of match calculation methods for optimum sizing of PV/wind hybrid system is presented. In this method, the more accurate and practical mathematic models for characterizing PV module, wind generator and battery are adopted; combining with hourly measured meteorologic data and load data, the performance of a PV/wind hybrid system is determined on a hourly basis; by fixing the capacity of wind generators, the whole year's LPSP (loss of power supply probability) values of PV/wind hybrid systems with different capacity of PV array and battery bank are calculated, then the trade-off curve between battery bank and PV array capacity is drawn for the given LPSP value; the optimum configuration which can meet the energy demand with the minimum cost can be found by drawing a tangent to the trade-off curve with the slope representing the relationship between cost of PV module and that of the battery. According to this match calculation method, a set of match calculation programs for optimum sizing of PV/wind hybrid systems have been developed. Applying these match calculation programs to an assumed PV/wind hybrid system to be installed at Waglan island of Hong Kong, the optimum configuration and its hourly, daily, monthly and yearly performances are given. (C) 2003 Elsevier Science Ltd. All rights reserved.

Unattended ground sensor system based on fiber optic disk accelerometer

The basic principle and critical characteristics of unattended ground sensors (UGS) based on fiber optic disk accelerometers are introduced. Mechanical principles of fiber optic disk accelerometers (FODA) and calculation methods are presented. An FODA with a high sensitivity of 120rad/g and a resonance frequency of 300Hz is designed and used for detection in military affair.

Inter-simple sequence repeat (ISSR) analysis of genetic variation of Chondrus crispus populations from North Atlantic

ISSR analysis was used to investigate genetic variations of 184 haploid and diploid samples from nine North Atlantic Chondrus crispus Stackhouse populations and one outgroup Yellow Sea Chondrus ocellatus Holmes population. Twenty-two of 50 primers were selected and 163 loci were scored for genetic diversity analysis. Genetic diversity varied among populations, percentage of polymorphic bands (PPB) ranged from 27.0 to 55.8%, H(Nei's genetic diversity) ranged from 0.11 to 0.20 and I(Shannon's information index) ranged from 0.16 to 0.30. Estimators PPB, H and I had similar values in intra-population genetic diversity, regardless of calculation methods. Analysis of molecular variance (AMOVA) apportioned inter-population and intra-population variations for C crispus, showing more genetic variance (56.5%) occurred in intra-population, and 43.5% variation among nine populations. The Mantel test suggested that genetic differentiation between nine C. crispus populations was closely related with geographic distances (R = 0.78, P = 0.002). Results suggest that, on larger distance scale (ca. > 1000 km), ISSR analysis is useful for determining genetic differentiations of C crispus populations including morphologically inseparable haploid and diploid individuals. (c) 2007 Elsevier B.V. All rights reserved.

水下机器人耐压舱弹塑性稳定性的一种简易计算方法

耐压舱的稳定性设计是水下机器人设计中的重要问题之一 .本文针对耐压舱的设计问题提出了一种简便的计算方法 ,并与不同计算方法的结果进行了对比

基于模型的立体视觉的优化方法

针对 3D视觉检测中最典型的误差源图像中像素的量化误差 ,在已知模型的条件下 ,对双目立体视觉提出一种模型。利用该优化模型及改进的约束最小二乘法对未知模型的立体视觉解法做一些改进 ,可以明显减小系统的误差。仿真结果表明 ,与未知模型的立体视觉方法相比 ,在同样的量化误差条件下 ,该方法可将系统误差减小 50 %以上。

一种基于视觉的移动机器人定位系统

具有自主的全局定位能力是自主式移动机器人传感器系统的一项重要功能 .为了实现这个目的 ,国内外均在不断地研究发展各种定位传感器系统 .这里介绍了一种采用光学原理的全方位位置传感器系统 .该传感器系统由主动式路标、视觉传感器、图象采集与数据处理系统组成 .其视觉传感器和数据处理系统可安装在移动机器人上 ,然后可通过观测路标和视角定位的方法 ,计算出机器人在世界坐标系中的位置和方向 .实验证明 ,该系统可以实现机器人的在线定位 ,其采样速率和精度能够满足实用要求 .