Computer Simulation for Haulage Performance of Power Tiller
The presence of a large number of marginal and small land holdings in India has rendered the power tiller to be the most suitable farm equipment for field operations, in view of its compact size, profitability and versatility, but the transport work which is also required to carry the farm produce is yet to be proved. Keeping these in mind, user friendly software was developed for predicting the haulage performance of power tiller to meet requirements in educational and research organizations. The developed software requires input parameters such as power tiller, trolley and operating conditions. The developed software was validated by conducting experiments with a 6.7 kW power tiller using a suitable trolley on tarmacadam road at various payloads and road slopes. The draft, slip, fuel consumption and speed were measured and other haulage performance parameters were calculated based on measured values to validate the developed software. The results simulated by software indicate lower draft and slip in the range of 1-23 and 2-9% with respect to the experimental data, however, higher transport productivity was in the range of 3-12%.
A program for predicting tractor performance in Visual C
Abstract A tractor performance program that predicts the performance of two-wheel-drive (2WD) and four-wheel-drive/mechanical-front-wheel-drive (4WD/MFWD) tractors on agricultural soils for both bias-ply and radial tires was developed to meet the user requirements for both educational and research programs. The program was written in Visual C++ programming language as a new method of predicting 2WD and 4WD/MFWD tractor performance. The program provides an intuitive user interface by linking databases such as tractor specifications, tire data (front, bias-ply, and radial), and traction equation coefficients to predict the performance of a selected tractor and model. The program has been proven to be user friendly and efficient.
Comparative study of in vitro flow characteristics between a human aortic valve and a designed aortic valve and six corresponding types of prosthetic heart valves.
A model of a pulsatile cardiovascular system is described including an electronic control, a hydraulic driving unit, a volume storage, a peripheral resistance and measuring equipment. Six different artificial heart valves, a designed aortic valve (Aachen pockett valve II) and a human aortic valve have been tested in the outflow position of the pump. Three of them are presently being used in clinical applications. Measurements of pressure and volume flow have been obtained for different frequencies n, pump volumes Vp and time ratios between pressure and suction phase. From the experimental results a comparative evaluation was deducted for different working conditions. In comparison to natural human aortic valve (NK) large volume flow is verified by the Aachen pocket valve II (AT), the Gott-Dagget value (GD), the Starr-Edwards valve (SE) and the Lillehei-Kaster valve (LK). The Gott-Daggett valve has the smallest back flow volume. The Smeloff-Cutter and in particular the Wada-Cutter valve have the largest regurgitation. This is to be expected since the Cutter valves are purposely so designed that they do not close tightly in order to avoid blood sedimentation. The human aortic valve, the Gott-Daggett valve and the Aachen pocket valve demonstrate the most favourable opening-closing characteristics. The human aortic valve achieves a negligible pressure loss, followed by the Björk-Shiley and the Lillehei-Kaster valve.