Aerodynamic pressure variation over SMA wire integrated morphing aerofoil

An analysis of the pressure variation over an aerofoil with integrated Shape Memory Alloy (SMA) wire is reported. A computational model based on finite elements and potential flow computation is proposed to obtain the deflections of the upper and the lower skins of the aerofoil subjected to aerodynamic pressure and hysteretic deformation of the SMA wire. The computational model couples a one-dimensional phenomenological constitutive model of SMA wire with the laminar incompressible aerodynamic pressure induced deformation of the aerofoil skins. The SMA wires are actuated by thermoelectric control system with auxiliary compensator feeding the piezoelectric stack actuators to adjust the hysteretic dynamics of the SMA wire. At each step of this coupled deformation process, the deflected/morphed shape of the aerofoil is d while recalculating to get the pressure distribution. Panel method based on incompressible and inviscid flow is employed for this purpose. The aerodynamic lift is then obtained from the pressure distributions. Numerical results on the variation of coefficient of pressure are reported.

Swarm intelligence algorithms for integrated optimization of piezoelectric actuator and sensor placement and feedback gains

Swarm intelligence algorithms are applied for optimal control of flexible smart structures bonded with piezoelectric actuators and sensors. The optimal locations of actuators/sensors and feedback gain are obtained by maximizing the energy dissipated by the feedback control system. We provide a mathematical proof that this system is uncontrollable if the actuators and sensors are placed at the nodal points of the mode shapes. The optimal locations of actuators/sensors and feedback gain represent a constrained non-linear optimization problem. This problem is converted to an unconstrained optimization problem by using penalty functions. Two swarm intelligence algorithms, namely, Artificial bee colony (ABC) and glowworm swarm optimization (GSO) algorithms, are considered to obtain the optimal solution. In earlier published research, a cantilever beam with one and two collocated actuator(s)/sensor(s) was considered and the numerical results were obtained by using genetic algorithm and gradient based optimization methods. We consider the same problem and present the results obtained by using the swarm intelligence algorithms ABC and GSO. An extension of this cantilever beam problem with five collocated actuators/sensors is considered and the numerical results obtained by using the ABC and GSO algorithms are presented. The effect of increasing the number of design variables (locations of actuators and sensors and gain) on the optimization process is investigated. It is shown that the ABC and GSO algorithms are robust and are good choices for the optimization of smart structures.

On the cut‐on frequencies of a large round duct with azimuthal as well as radial partitions

This letter deals with a three‐dimensional analysis of circular sectors and annular segments resulting from the partitioning of a round (cylindrical) duct for use in an active noise control system. The relevant frequency equations are derived for stationary medium and solved numerically to arrive at the cut‐on frequencies of the first few modes. The resultant table indicates among other things that azimuthal partitioning does not raise the cutoff frequency (the smallest cut‐on frequency) beyond a particular value, and that radial partitioning is counterproductive in that respect.

Bypass operation in bridge convertors for high-voltage d.c. transmission

Bypass operation with the aid of a special bypass valve is an important part of present-day schemes of protection for h.v. d.c. transmission systems. In this paper, the possibility of using two valves connected to any phase in the bridge convertor for the purpose of bypass operation is studied. The scheme is based on the use of logic circuits in conjunction with modified methods of fault detection. Analysis of the faults in a d.c. transmission system is carried out with the object of determining the requirements of such a logic-circuit control system. An outline of the scheme for the logic-circuit control of the bypass operation for both rectifier and invertor bridges is then given. Finally, conclusions are drawn regarding the advantages of such a system, which include reduction in the number of valves, prevention of severe faults and fast clearance of faults, in addition to the immediate location of the fault and its nature.

Application of Solar Powered High Voltage Discharge Plasma for NOX Removal in Diesel Engine Exhaust

This paper proposes a compact electric discharge plasma source for controlling NOX emission in diesel engine exhaust. Boost converter is used to boost to solar powered battery voltage to 24V, further an automobile ignition coil was used to generate the high voltage pulse using fly-back topology. This design is aimed at retrofitting the existing catalytic converters with pulse assisted cleaning technique. In this paper we bring out a relative comparison of discharge plasma and plasma-adsorbent process at different gas flow rates. Activated alumina was used as adsorbent. The main emphasis is laid on the development of a compact pulse source from 12V battery, which is powered by the solar, for the removal of NOX from the filtered diesel engine exhaust.

Evaporation Heat Transfer Coefficient in a Capillary Pumped Loop and Loop Heat Pipe for Different Working Fluids

Capillary pumped loop (CPL) and loop heat pipe (LHP) are passive two-phase heat transport devices. They have been gaining importance as a part of the thermal control system of spacecraft. The evaporation heat transfer coefficient at the tooth-wick interface of an LHP or CPL has a significant impact on the evaporator temperature. It is also the main parameter in sizing of a CPL or LHP. Experimentally determined evaporation heat transfer coefficients from a three-port CPL with tubular axially grooved (TAG) evaporator and a TAG LHP with acetone, R-134A, and ammonia as working fluids are presented in this paper. The influences of working fluid, hydrodynamic blocks in the core, evaporator configuration (LHP or CPL), and adverse elevation (evaporator above condenser) on the heat transfer coefficient are presented.

Mitigation of lower order harmonics in a grid-connected single-phase PV inverter

In this paper, a simple single-phase grid-connected photovoltaic (PV) inverter topology consisting of a boost section, a low-voltage single-phase inverter with an inductive filter, and a step-up transformer interfacing the grid is considered. Ideally, this topology will not inject any lower order harmonics into the grid due to high-frequency pulse width modulation operation. However, the nonideal factors in the system such as core saturation-induced distorted magnetizing current of the transformer and the dead time of the inverter, etc., contribute to a significant amount of lower order harmonics in the grid current. A novel design of inverter current control that mitigates lower order harmonics is presented in this paper. An adaptive harmonic compensation technique and its design are proposed for the lower order harmonic compensation. In addition, a proportional-resonant-integral (PRI) controller and its design are also proposed. This controller eliminates the dc component in the control system, which introduces even harmonics in the grid current in the topology considered. The dynamics of the system due to the interaction between the PRI controller and the adaptive compensation scheme is also analyzed. The complete design has been validated with experimental results and good agreement with theoretical analysis of the overall system is observed.

ADAPTATION OF MW LEVEL NATURAL GAS LEAN BURN ENGINE FOR PRODUCER GAS OPERATION A GRID CONNECTED POWER PLANT

Availability of producer gas engines at MW being limited necessitates to adapt engine from natural gas operation. The present work focus on the development of necessary kit for adapting a 12 cylinder lean burn turbo-charged natural gas engine rated at 900 kWe (Waukesha make VHP5904LTD) to operate on producer and set up an appropriate capacity biomass gasification system for grid linked power generation in Thailand. The overall plant configuration had fuel processing, drying, reactor, cooling and cleaning system, water treatment, engine generator and power evacuation. The overall project is designed for evacuation of 1.5 MWe power to the state grid and had 2 gasification system with the above configuration and 3 engines. Two gasification system each designed for about 1100 kg/hr of woody biomass was connected to the engine using a producer gas carburetor for the necessary Air to fuel ratio control. In the use of PG to fuel IC engines, it has been recognized that the engine response will differ as compared to the response with conventional fueled operation due to the differences in the thermo-physical properties of PG. On fuelling a conventional engine with PG, power de-rating can be expected due to the lower calorific value (LCV), lower adiabatic flame temperature (AFT) and the lower than unity product to reactant more ratio. Further the A/F ratio for producer gas is about 1/10th that of natural gas and requires a different carburetor for engine operation. The research involved in developing a carburetor for varying load conditions. The patented carburetor is based on area ratio control, consisting of a zero pressure regulator and a separate gas and air line along with a mixing zone. The 95 litre engine at 1000 rpm has an electrical efficiency of 33.5 % with a heat input of 2.62 MW. Each engine had two carburetors designed for producer gas flow each capable of handling about 1200 m3/hr in order to provide similar engine heat input at a lower conversion efficiency. Cold flow studies simulating the engine carburetion system results showed that the A/F was maintained in the range of 1.3 +/- 0.1 over the entire flow range. Initially, the gasification system was tested using woody biomass and the gas composition was found to be CO 15 +/- 1.5 % H-2 22 +/- 2% CH4 2.2 +/- 0.5 CO2 11.25 +/- 1.4 % and rest N-2, with the calorific value in the range of 5.0 MJ/kg. After initial trials on the engine to fine tune the control system and adjust various engine operating parameter a peak load of 800 kWe was achieved, while a stable operating conditions was found to be at 750 kWe which is nearly 85 % of the natural gas rating. The specific fuel consumption was found to be 0.9 kg of biomass per kWh.

BIOMASS GASIFICATION TO SUBSTITUTE FOSSIL FUEL IN FOOD INDUSTRY

Food industries like biscuit and confectionary use significant amount of fossil fuel for thermal energy. Biscuit manufacturing in India is carried out both by organized and unorganized sector. The ratio of organized to unorganized sector is 60 : 40 (1). The total biscuit manufacturing in the organized sector India in 2008 was about 1.7 million metric tons (1). Accounting for the unorganized sector in India, the total biscuit manufacturing would have been about 2.9 million metric tons/annum. A typical biscuit baking is carried in a long tunnel kiln with varying temperature in different zones. Generally diesel is used to provide the necessary heat energy for the baking purpose, with temperature ranging from 190 C in the drying zone to about 300 C in the baking area and has to maintain in the temperature range of +/- 5 C. Typical oil consumption is about 40 litres per ton of biscuit production. The paper discusses the experience in substituting about 120 lts per hour kiln for manufacturing about 70 tons of biscuit daily. The system configuration consists of a 500 kg/hr gasification system comprising of a reactor, multicyclone, water scrubbers, and two blowers for maintaining the constant gas pressure in the header before the burners. Cold producer gas is piped to the oven located about 200 meters away from the gasifier. Fuel used in the gasification system is coconut shells. All the control system existing on the diesel burner has been suitably adapted for producer gas operation to maintain the total flow, A/F control so as to maintain the temperature. A total of 7 burners are used in different zones. Over 17000 hour of operation has resulted in replacing over 1800 tons of diesel over the last 30 months. The system operates for over 6 days a week with average operational hours of 160. It has been found that on an average 3.5 kg of biomass has replaced one liter of diesel.

Direct Measurement of Three-Dimensional Forces in Atomic Force Microscopy

Direct measurement of three-dimensional (3-D) forces between an atomic force microscope (AFM) probe and the sample benefits diverse applications of AFM, including force spectroscopy, nanometrology, and manipulation. This paper presents the design and evaluation of a measurement system, wherein the deflection of the AFM probe is obtained at two points to enable direct measurement of all the three components of 3-D tip-sample forces in real time. The optimal locations for measurement of deflection on the probe are derived for a conventional AFM probe. Further, a new optimal geometry is proposed for the probe that enables measurement of 3-D forces with identical sensitivity and nearly identical resolution along all three axes. Subsequently, the designed measurement system and the optimized AFM probe are both fabricated and evaluated. The evaluation demonstrates accurate measurement of tip-sample forces with minimal cross-sensitivities. Finally, the real-time measurement system is employed as part of a feedback control system to regulate the normal component of the interaction force, and to perform force-controlled scribing of a groove on the surface of polymethyl methacrylate.

Laser drilling improving circuit board manufacturing

We reported here a novel technique for laser high speed drillings on Printed Circuit Boards (PCBs). A CNC solid laser based system is developed to drill through and blind vias as an alternative to mechanical drilling. The system employs an Acousto-Optic Q-switched Nd: YAG laser, a computer control system and an X-Y moving table which can handle up to 400 x 400 mm PCB. With a special designed cavity the laser system works in a pulsed operation in order to generate pulses with width down to 0.5 mu s and maximum peak power over 10kW at 10k repetition rate. Delivered by an improved optical beam transforming system, the focused laser beam can drill hobs including blind vias on PCBs with diameter in the range of 0.1 - 0.4 mm and at up to 300 - 500 vias per second (depending on the construction of PCBs). By means of a CNC X-Y moving system, laser pulses with pulse-to-pulse superior repeatability can be fired at desired location on a PCBs with high accuracy. This alternative technology for drilling through or blind vias on PCBs or PWBs (printed wiring boards) will obviously enhance the capability to printed boards manufacturing.

KD-4型可动凝胶调驱体系研究与应用

针对中高温油藏调驱中使用的含醇类酚醛树脂类交联剂在现场应用中存在结块、醇的挥发性等问题，开展了可动凝胶合成技术、配方组成、成胶时间、热稳定性考察等试验研究，形成了以全水溶、高羟甲基化的预聚树脂交联剂为主体的KD-4型调驱体系配方。对KD-4型调驱体系成胶时间、热稳定性等进行了室内实验，并开展了前置段塞物模试验和可动性物模试验研究。依据试验结果，将总体段塞设计为“前置段塞＋主段塞＋保护段塞＋驱油段塞（视井况而定）”，成胶黏度由低到高。自2006年7月以来，该技术进行了6口井的现场应用，井组有效率100％，截至2007年10月底，按驻点法统计，累计阶段增产原油16158．7t，目前继续有效，措施效果显著，说明调驱性能稳定，方案设计科学.

基于B/S的海洋平台远程监控系统设计

本文提出基于浏览器/服务器（Browser/Server简写为B/S）海洋平台结构的远程监测控制系统,实现在客户端不间断对平台进行实时监视,获得现场采集数据,并以图形方式进行实时显示,从而为平台的安全运行和结构设计提供科学依据。

Estudio del comportamiento térmico del instrumento TriboLAB durante su estancia en la Estación Espacial Internacional desde la perspectiva del análisis de datos funcionales

[ES]El objetivo principal de esta tesis de máster es el estudio del comportamiento térmico del instrumento TriboLAB durante su estancia en la Estación Espacial Internacional, junto con la comparación de dicho comportamiento con el pronosticado por los modelos térmicos matemáticos empleados en el diseño de su sistema de control térmico. El trabajo realizado ha permitido profundizar de forma importante en el conocimiento del mencionado comportamiento. Ello permitirá poner a disposición de otros experimentadores interesados en ubicar sus instrumentos en los balcones exteriores de la Estación Espacial Internacional, información real acerca del comportamiento térmico de un equipo de las características del TriboLAB en dichas condiciones. Información de gran interés para ser empleada en el diseño del control térmico de sus instrumentos, especialmente ahora que la vida útil de la Estación Espacial Internacional ha sido prorrogada hasta 2020. El control térmico de los equipos espaciales es un aspecto clave para asegurar su supervivencia y correcto funcionamiento bajo las extremas condiciones existentes en el espacio. Su misión es mantener los distintos componentes dentro de su rango de temperaturas admisibles, puesto que en caso contrario no podrían funcionar o incluso ni siquiera sobrevivir más allá de esas temperaturas. Adicionalmente ha sido posible comprobar la aplicabilidad de distintas técnicas de análisis de datos funcionales en lo que respecta al estudio del tipo de datos aquí contemplado. Así mismo, se han comparado los resultados de la campaña de ensayos térmicos con los modelos térmicos matemáticos que han guiado el diseño del control térmico, y que son una pieza fundamental en el diseño del control térmico de cualquier instrumento espacial. Ello ha permitido verificar tanto la validez del sistema de control térmico diseñado para el TriboLAB como con la adecuada similitud existente entre los resultados de los modelos térmicos matemáticos y las temperaturas registradas en el equipo. Todo ello, ha sido realizado desde la perspectiva del análisis de datos funcionales.