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Some special features of cloud-to-ground (CG) lightning discharges in the verge of Qinghai-Tibetan Plateau have been found by using the data from wide-band slow antenna system with 1μs time resolution. It has been found that (CG) lightning usually follows intracloud (IC) discharges. K-changes during the IC discharge part initiate from negative charge region and propagate downward to the lower positive charge region with an average speed of 1.5×107 m/s. The radiation waveforms of return stoke begin with a slow front which last for about 9.4 μs to about half of the field peak amplitude, and the zero-to-peak rise time was 10.9μs for negative first return strokes.

The application of total variation diminishing (TVD) implicit and explicit schemes to transonic flow around airfoils is presented. Several upwind and symmetric TVD flux limiters from the Non-MUSCL family are examined and compared with Jameson's non-linear artificial dissipation model. Inviscid results indicate that TVD schemes reduce shock smearing while practically eliminating numerical oscillations. Analytical results are presented for a NACA 0012 airfoil for various transonic flow conditions using TVD formulations of the 2D Navier-Stokes equations. Comparisons of computed results with experimental data show good agreement.

An improved system for total cylinder sampling from an indirect injection passenger car type diesel engine has been developed. The system utilizes explosively actuated cutters which cut aluminum diaphragms in both the main combustion chamber and precombustion chamber at a predetermined time. The cylinder charge is rapidly cooled and diluted as it flows from the chambers into the sampling system. When sampling from near top dead center, cylinder pressure decay half times of about 0.5 ms have been achieved. The system has been used to determine NOx concentrations in the cylinder as a function of crankangle position at 1000 rpm with equivalence ratios of 0.32, 0.52, and 0.60. NOx concentrations rise rapidly shortly after the onset of combustion, attain maxima which are 2 to 10% higher than corresponding exhaust concentrations at about 5-10 crankangle degrees after the end of the fuel injection process and then slowly decay to exhaust levels.

A dumping apparatus has been developed and tested for total cylinder sampling from an indirect injection diesel engine. The apparatus design is described in detail along with the experimental system. The system performance is given for one engine operating condition. Graphs of main chamber and pre-chamber pressures versus crankangle are also included. The system demonstrated a sampling accuracy of ±2 degrees of crankangle.