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Computational Support for the Collaborative D...
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This thesis discusses the use of a cooperative, agent-based search in the cable harness routing problem (CHRP). They hypothesis behind this work is that a human designer can be greatly assisted in the intricate task of routing cables through a complex space if he is empowered to interact naturally with other autonomous agents as well as with the design itself. A collection of automated search and routing agents, which make use of domain knowledge and which are able to communicate with the human designer, is discussed. In addition, this thesis presents a novel interactive routing environment in which each agent is able to communicate design fragments with others via an adaptive, genetic-based blackboard. |
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Tunable Thermal Conductivity
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This paper lists methods for tuning and enhancing thermal conductivity. Heat transfer applications have a lot of challenges such as, raise the thermal conductivity, control thermal conductivity to be changeable within the same application, and working in very accurate applications like micro combustors and electronic etc. All these requirements couldn’t be achieved by the traditional methods of heat transfer. Therefore, a lot of techniques which are related mainly to the nanotechnology are working on these issues. In this paper we will subjected to some of the methods of tuning thermal conductivity in order to control the heat transfer process. |
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Laser-Induced Breakdown Spectroscopy – A Lite...
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This paper lists the principles of Laser-Induced Breakdown Spectroscopy (LIBS) and gives a brief review of some research work done on its tilization in the applications of the detection of aerosols and fine particles in gaseous flows. Laser-induced breakdown spectrometry (LIBS), also referred to as laser-induced plasma spectroscopy, is one of the new spectroscopy techniques developed by adopting high power, pulsed and narrow bandwidth lasers. The LIBS system is a stand-off or remote sensing technique which permits non-intrusive qualitative and quantitative measurements. The principle of the LIBS technique is illustrated in figure (1). A pulsed laser beam is focused at the test point and produces a spark due to the high electric field. The spark generates high-density plasma which excites various atomic elements present in the focal volume. |
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Fiber-Optic based Dynamic Pressure sensor for...
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Acquiring accurate, transient measurements in harsh environments has always pushed the limits of available measurement technology. Until recently, the technology to directly measure certain properties in extremely high temperature environments has not existed. Advancements in optical measurement technology have led to the development of measurement techniques for pressure, temperature, acceleration, skin friction, etc. using extrinsic Fabry-Perot interferometry (EFPI). The basic operating principle behind EFPI enables the development of sensors that can operate in the harsh conditions associated with turbine engines, high-speed combustors, and other aerospace propulsion applications where the flow environment is dominated by high frequency pressure and temperature variations caused by combustion instabilities, blade-row interactions, and unsteady aerodynamic phenomena. Using micromachining technology, these sensors are quite small and therefore ideal for applications where restricted space or minimal measurement interference is a consideration. In order to help demonstrate the general functionality of this measurement technology, sensors and signal processing electronics currently under development by Luna Innovations were used to... |
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Experimental Study of Compressible Pipe Flow ...
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Anna Ekblom Johan Gullman-Strand's (KTH Sweeden) work on compressible pipe flow with friction and heat addition. The aim of the presented work was to compare existing theoretical analysis with experimental results in the feld of compressible pipe ow in a straight circular pipe with constant cross section area subjected to wall friction and heat addition. The equations describing pipe ow subjected to friction have been rederived. Two different models have been compared. The experiments were conducted on four pipes differing in length and friction factor.Quantities such as total inlet pressure, total inlet temperature, static pressure distribution along the pipe, venturi nozzle pressure difference, power added, outlet dynamic pressure distribution and outlet total temperature have been measured in order to determine the dependence on heat addition and friction. There was no apparent effect of heating on the fl ow eld though the input power was entirely transfered to the ow. The in uence of friction seems to have the predicted effect, since the achieved outlet Mach numbers were similar for all four pipes for similar input conditions. Inn contrast to the theoretical model of one-dimensional ow, the outlet Ma... |
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The Behaviour of Air (Nitrogen) inside Carbon...
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This paper shows how Air (Nitrogen) is not a gas inside a Carbon nanotube, as inferred from the results of a Monte Carlo simulation of Nitrogen molecules in the presence of 2 surfaces. The surface under study was composed of Carbon, and the length scale was a few dozen nanometers, which made the problem representative of air inside a carbon nanotube. The surfaces have been shown to increase the compressibility of the gas, but the gas almost completely adsorbs onto the surface at room temperature due to the strong surface interaction potential. Therefore, it can also be deduced that Nitrogen is not quite a gas inside a Carbon nanotube. |
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Global Continuity in Stokes’ Flow
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Creeping flow (flow with Re << 1) past a sphere is described by Stokes’* celebrated solution (1851). The solution is formulated with the help of the streamfunction which ensures mass conservation on a differential level. However, if the streamlines and velocity contours for this flow are plotted, the image suggests that global continuity is violated. This can often lead to some confusion and doubt over the validity of the solution, so a simple demonstration follows to show that Stokes’ solution also satisfies global mass conservation, despite the illusion presented by the streamlines and velocity contours. |
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Plasma Wind Tunnels
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Various plasma wind tunnels have been built for developing reusable space transportation systems and space probes entering the atmospheres of celestial bodies. All together they cover almost the whole reentry trajectory of a space craft. They generate continuous plasma flows of high specific enthalpy and velocity with thermal or magnetoplasmadynamic generators. Plasma wind tunnels are used for:(1) Development and qualification of radiation and ablative cooling materials and thermal protection systems (2) Validation of numerical codes for reentry prediction (3) Development and qualification of reentry measurement devices |
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Hydrogen sensors based on titania nano-tubes
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This article is a literature survey on the fabrication of novel H2 sensors based on titania nano-tubes prepared using anodization and annealed in an oxygen atmosphere. The as prepared nano-tubes are amorphous but they crystallize on annealing at elevated temperatures and are structurally stable (which is a requirement of any sensor) to at least 600 °C.Titania nano-tubes are grown from titanium foil (≈99.5% pure) of thickness 0.25 mm. The anodization is performed in an electrolyte medium of 0.5% hydrofluoric acid in water, using a platinum foil cathode. A well defined nano-tube architecture results, with nano-tube length of 400 nm in approximately 20 minutes.Measurement of H2 concentration is based on the increase in conductivity of the nano-tube surface in a hydrogen ambient as compared to its original conductivity, and this is quantified by ’sensitivity’ ratio, S = (R0 – Rgas)/Rgas (where R0 is the electrical resistance of the sensor before passing the gas and Rgas that after passing gas and reaching the saturation value). The sensor shows significant hydrogen sensitivity, with a three order of magnitude change in resistance as compared to its original resistance. The major process behind the interaction between the nano-tu... |
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