Analysis of a metal hydride reactor for hydrogen storage

In this paper a two-dimensional model of an annular cylindrical reactor filled with metal hydride suitable for hydrogen storage is presented. Comparison of the computed bed temperatures with published experimental data shows a reasonably good agreement except for the initial period. Effects of hydrogen pressure and external fluid temperatures on heat transfer and entropy generation are obtained. Results show that the time required for hydrogen charging and discharging is higher when the thermal capacity of the reactor wall is considered. The time required for absorption and desorption can be reduced significantly by varying the hydrogen gas pressure and external fluid temperatures. However, along with reduction in time the entropy generated during hydrogen storage and discharge increases significantly. Results also show that for the given input conditions, heat transfer between the external fluid and hydride bed is the main source of entropy generation.     

Macroporous WO3: Tunable morphology as a function of glycine concentration and its excellent acetone sensing performance

Materials-by-Design symbolizes the development of advanced materials with cost and time -effective experimentation. Here, we show the single and unique strategy of developing macroporous WO₃ with different morphologies (nano to micro) using glycine as structure assisting agent. The developed structures were analyzed with various characterizing tools, and tested for practical application as acetone gas sensor (83.87% for 10?ppm). The morphological correlation with the sensitivity is described.     

Measurement of yaw,pitch and side-force on a lifting model in a hypersonic shock tunnel

Yawing moment, pitching moment and side-force on a blunt, triangular, lifting model were measured in a shock tunnel using an accelerometer balance at a hypersonic Mach number of 8. The measurements were carried out at different angles of incidence of the model with the freestream. The balance was instrumented with accelerometers to sense the model acceleration in the desired directions, and was equipped with a soft suspension system such that the model had a free flight during the tests in the shock tunnel. Pressure measurements on the surfaces of the model were carried out using high frequency pressure transducers to validate the output of the force balance. The moment and force coefficients obtained through both the measurement techniques have a good agreement reciprocally. The force and moment coefficients for the test model were analytically estimated using Newtonian theory to compare with the measured coefficients. The comparison between theory and experiments has been found quite encouraging.     

Evaluation of the effects of machining parameters on MQL based surface grinding process using response surface methodology

Journal of Mechanical Science and Technology - Grinding is a precision machining process widely used for close tolerance and good surface finish. Due to aggregate of geometrically undefined cutting...     

Hierarchical WSN protocol with fuzzy multi-criteria clustering and bio-inspired energy-efficient routing (FMCB-ER)

Multimedia Tools and Applications - Wireless Sensors Network (WSN) is used for monitoring and recording the physical environment and to transfer the sensed data to a central location by means of...     

Crisis Management

Multiple recent disasters have put crisis management in the limelight. Consequently, many IT-related research efforts are under way to bring transformational changes to first responder and response organizations’ ability to contain and mitigate crises.     

CFD based performance analysis of a solar air heater duct provided with artificial roughness

In the present work the performance of a solar air heater duct provided with artificial roughness in the form of thin circular wire in arc shaped geometry has been analysed using Computational Fluid Dynamics (CFD). The effect of arc shaped geometry on heat transfer coefficient, friction factor and performance enhancement was investigated covering the range of roughness parameter (relative roughness height (e/D) from 0.0299 to 0.0426 and relative roughness angle (α/90) from 0.333 to 0.666) and working parameter (Reynolds number, Re from 6000 to 18,000 and solar radiation of 1000 W/m2). Different turbulent models have been used for the analysis and their results are compared. Renormalization-group (RNG) k-? model based results have been found in good agreement and accordingly this model is used to predict heat transfer and friction factor in the duct. The overall enhancement ratio has been calculated in order to discuss the overall effect of the roughness and working parameters. A maximum value of overall enhancement ratio has been found to be as 1.7 for the range of parameters investigated.     

A switch-level test generation system for synchronous and asynchronous circuits

A switch-level test generation system for synchronous and asynchronous circuits has been developed in which a new algorithm for fully automatic switch-level test generation and an existing fault simulator have been integrated. For test generation, a switch-level circuit is modeled as a logic network that correctly models the behavior of the switch-level including bidirectionality, dynamic charge storage, and ratioed logic. The algorithm is able to generate tests for combinational and sequential circuits. BothnMOS and CMOS circuits can be modeled. In addition to the classical line stuck-at faults, the algorithm is able to handle stuck-open and stuck-closed faults on the transistors of the circuit.In synchronous circuits, the time-frame based algorithm uses asynchronous processing within each clock phase to achieve stability in the circuit and synchronous processing between clock phases to model the passage of time. In asynchronous circuits, the algorithm uses asynchronous processing to reach stability within and between modules. Unlike earlier time-frame based test generators for general sequential circuits, the test generator presented uses the monotonicity of the logic network to speed up the search for a solution. Results on benchmark circuits show that the test generator outperforms an existing switch-level test generator both in time and space requirements. The algorithm is adaptable to mixed-level test generation.     

Methyltrimethoxysilane based monolithic silica aerogels via ambient pressure drying

We have developed a novel route to monolithic silica aerogels via ambient pressure drying by the acid–base sol–gel polymerization of methyltrimethoxysilane (MTMS) precursor. An extent of silica polymerization in the alcogels plays a crucial role in obtaining the monolithic aerogels which could be optimized by a proper control over the MeOH/MTMS molar ratio (S) during the sol–gel synthesis. The alcogel undergoes the distinct “spring-back effect” at the critical stage of the drying and thereby preserving the highly porous silica network without collapse. The process yields silica aerogels exhibiting very low bulk density and high specific surface area of 0.062 g/cm³ and 520 m²/g, respectively. The average pore diameter and the cumulative pore volume varied from 4.5 to 12.1 nm and 0.58 to 1.58 cc/g, respectively. In addition, the aerogels are superhydrophobic with contact angle as high as 152°. We anticipate that the new route of the monolithic silica aerogel production will greatly expand the commercial exploitation of these materials.