Applied Mechanics and Materials Vol. 575

Abstract: The flat plate collector is a device used for harnessing the solar energy. The efficiency of this device is dependent on the various heat losses. These losses are bottom loss, side loss, edge loss, corner loss, sealing loss & top loss. These losses are measured as well as recorded. There are forty eight thermocouples located at different points. The input energy is through the electric heaters to the collector. These heaters are kept below the absorber. The capacity of each heater is 0.5 kW. These heaters are two in number. The wind velocity is measured by the vane type anemometer. The input heat flux is kept constant & wind velocity is varied. The evaluation of various heat losses is important for the performance evaluation of the collector. Generally the upward heat losses play an important role in the total heat losses. The present paper is an experimental simulation of a horizontal single glazed flat plate collector. The losses are measured under steady state conditions at different wind velocity & keeping 90⁰ yaw angle and at zero tilt angle.

Abstract: We have fabricated p-type monocrystalline silicon (Si) solar cell with phosphorus (P) screen-printed n+ emitter and investigated its electrical and structural properties. During P screen-printed n+ emitter process, a 16 nm-thick phosphosilicate glass (PSG) layer was formed as a result of interaction between P-dopant paste and Si substrate. Due to the PSG reflow associated with the reduction of viscosity of oxide caused by the amount of P atoms in PSG layer, thinner and thicker PSG film was formed in convex and concave regions of the textured Si surface, respectively, which was quite different from the growth behavior of thermally grown SiO₂ layer. Due to a strong dependence of P diffusion on the Si interstitials, deeper and shallower junctions were abnormally formed near the convex and concave regions in the textured Si surface, respectively. The electric field and temperature dependence of the current-voltage characteristics demonstrated that the Poole-Frenkel barrier lowering mechanism along with the generation-recombination mechanism had dominance over the current conduction in the reverse bias region of p-type monocrystalline Si solar cell fabricated using screen printing process.

Abstract: Transparent conductive oxide (TCO) is one of the important components in dye-sensitized solar cells. The main requirements of TCO for dye-sensitized solar cells are having a low electrical resistance and a high light transmittance. This study focuses on the synthesis of fluorine-doped tin oxide including its optimization. The synthesis of fluorine-doped tin oxide has been conducted under spray pyrolysis technique in which a precursor solution of SnCl₂:F having concentration of 0.3, 0.5, 0.7, and 0.9 M. The spray pyrolysis was performed using a nebulizer with deposition time of 10 min. The glass substrate was heated at a temperature of 400, 450, and 500°C prior to deposition. The fluorine doped tin oxide was then measured the electrical resistivity for each area of ​​1 cm². Therefore, the mean and distribution of electrical resistivity of fluorine-doped tin oxide with an area of ​​10 x 10 cm then were predicted. In addition, the morphology and transmittance of fluorine-doped tin oxide are also examined. The optimization of the synthesis process of fluorine-doped tin oxide using spray pyrolysis was obtained at a concentration of 0.7 M with a sintering temperature of 400°C. The best fluorine-doped tin oxide has been also fabricated into the dye-sensitized solar cell and the performance has been studied.

Abstract: The main electromagnetic radiation source and the generating mechanism in low voltage frequency converter were defined and analyzed in this paper according to electromagnetic radiation theory together with the discussion of the impact on radiation from raise time, falling time of pulse width modulation (PWM) signal and carrier frequency, so that the radiation can be understood more exactly in term of numerical value change, which helps specifically reduction of converter radiation during design phase in compliance with related international standards and technical norms regarding industrial converter. Started with the theory of electromagnetic field the zone around converter were differentiated and analyzed based on the radiation characteristics. As main means of radiation suppression in converter shielding and grounding were quantitatively analyzed. A series of tests with different power rating converters verified the calculation and analysis. Consequently the design of converter was guided to meet the requirements of standard.

Abstract: An experimental study was conducted at Rewa, India (24°32′′N, 81°18′′E) in order to investigate the effect of the material of the body of a basin type solar still on its performance. Two single sloped basin type solar stills of G.I. sheet and F.R.P. respectively were constructed of equal basin area and size and were tested by keeping them side by side under identical conditions. Due to considerably lower thermal conductivity of F.R.P. as compared to that of G.I., around 30% higher productivity was observed in the former. The base heat loss as calculated with the help of the thermal model, in case of F.R.P. still was observed to be 36% which was much lower than 53% for G.I. still. The efficiency of the F.R.P. still was obtained as 32% whereas for G.I. still it was 26%.

Abstract: A novel parallel mechanism which enlarges the workspace by singularity-free mode change is proposed. The proposed mechanism is inherited the design of Linear DELTA which has three degree-of-freedom translational moving plate driven by three linear actuators, in addition, extended it by redundantly actuation by four linear actuators and asymmetric design. New criterions about redundancy and singularity of redundantly actuated parallel mechanism using summation and product of determinants of minor matrices of the transposed Jacobian matrix are proposed. Redundantly actuation and asymmetric design enables singularity-free mode changes with loss redundancy but maintain non-singularity, that are evaluated by the proposed criterions. Numerical simulations demonstrate the singularity-free mode changes of the proposed mechanism.

Abstract: The usage of Ionic Polymer-Metal Composite (IPMC) actuator as the propulsor for underwater robot has been worked out by many scientists and researchers. IPMC actuator had been selected due to its advantages such as low energy consumption, low operation noise and ability to work underwater. This paper presents the fabrication and characterization of the IPMC actuator. The IPMC actuator samples had been fabricated using electroless plating for three different thickness and lengths. The characterization was conducted to determine the influence of the thickness, length, input frequency, drive voltage and orientation angle on the tip force and output frequency. The results show that IPMC thickness has significant influence on the tip force generation and lower input frequency would results wider displacement. The recorded results are essential as future reference in developing the propulsor for the underwater robot.

Abstract: The designer should be familiar with the acceptable dimensions and material for model, which fulfils its performance requirements under stress and deformation. In this paper the design and failure analysis of track tensioner unit (TTU) of hybrid locomotion mobile robot is presented. The TTU is a module that helps the locomotion system transformability while robot moves on wheel or track mechanism. It is made of Aluminium alloy Al6061-T6 and was analyzed for its mechanical behaviour that subjected under different load conditions. The failure analysis gave the results about the material behaviour under loading condition that helps the selection of suitable one for design. The simulation result shows that the model material fails or deform permanently under 1000N load.

Abstract: Soft robots are robots made of soft materials and actuators. Previously we proposed the HPN (Honeycomb PneuNets) Robot, where PneuNets were placed as actuators into honeycomb shaped elastomer. In this paper, we present some progress of this effort. A random search algorithm is applied to plan the obstacle-avoid movements of an HPN robot. We test it through several cases, and the results showed that the algorithm can work effectively. We introduce an HPN robot prototype, which is made of RTV-2 silicone rubber. Preliminary experiments showed that some good expansion rate and flexibility can be achieved. A piston and soft body simulation model of HPN robots is also presented, which can mimic the basic behaviors of the HPN robot.

Abstract: In this paper, according to the requirements of the self-propelled-gun’s fire extinguisher bottle test technology, using variable speed metering pump technology, a variable cain pressure predictive controller is developed. The experiment is done, and experiment results show that the method can improve response speed of pump-valve combined control, and leak detection and pressure test of various types of fire extinguisher bottle is solved effectively. The trial operation proves: this test equipment is high common, high stability and high integration.