Operational testing of valve regulated lead acid batteries incommercial aircraft

Valve regulated lead acid (VRLA) batteries provide electrical performance that is virtually identical to sintered plate nickel-cadmium battery systems. In addition, the VRLA batteries offer the user a no-maintenance battery and other enhanced features that make this a very desirable battery for aircraft applications. In field trials, where VRLA batteries were substituted for nickel-cadmium batteries, the VRLA provided the user with a high reliability turbine engine starting battery under a wide variety of climatic conditions     

Advanced lithium ion battery charger

A lithium ion battery charger has been developed for four and eight cell batteries or multiples thereof. This charger has the advantage over those using commercial lithium ion charging chips in that the individual cells are allowed to be taper charged at their upper charging voltage rather than be cutoff when all cells of the string have reached the upper charging voltage limit. Since 30-60% of the capacity of lithium ion cells may be restored during the taper charge, this charger has a distinct benefit of fully charging lithium ion batteries by restoring all of the available capacity to all of its cells     

Relationship between daily variation of cosmogenic nuclide Be-7 concentration in atmosphere and solar activities

Daily Be-7 concentrations in air at the height of 15 m are continuously observed at 38°15.2′N, 140°20.9′E, between 2000 and 2001. The average concentration and the relative standard deviation were 4.0 mBq/m³ and 50% in 2000–2001, respectively. The Be-7 concentrations increased 2.5% with the decrease in the sunspot numbers by 6.7% for the term of two years. From the power spectral analysis, the periodicity of 26 days is shown for the daily Be-7 concentrations. The folding analysis indicates that the time variation of the Be-7 concentration is similar to that of the ground-based neutron counting rate, and the phase delay for the minimum portion of Be-7 concentration was roughly 8 days to the maximum sunspot number. These results indicate that the Be-7 concentrations in the air at ground level have 26 day periodicity as a component of time variations and the time variation is caused by the solar modulation of galactic cosmic rays, which corresponds to the variation of the sunspot number due to the rotation of the sun.     

MMAE-Based Control with Space-Time Point Process Observations

A multiple model adaptive estimator (MMAE) has been formulated to estimate the state of a dynamic system modeled by a linear stochastic differential equation, from which measurements, described as a noise-corrupted space-time point process functionally related to that state, are extracted. Assumed certainty equivalence is used to combine such an estimator with the LQ full-state feedback controller to synthesize a practical, implementable controller. Performance of the estimator and resultant controller characteristics are investigated via simulation as a function of approximation method used to limit the full-scale estimator to finite dimensionality and also as a function of important parameters defining the dynamics and observation processes.     

Synthesis of biomass and utilization of plants wastes in a physical model of biological life-support system

The paper considers problems of biosynthesis of higher plants' biomass and "biological incineration" of plant wastes in a working physical model of biological LSS. The plant wastes are "biologically incinerated" in a special heterotrophic block involving Californian worms, mushrooms and straw. The block processes plant wastes (straw, haulms) to produce soil-like substrate (SLS) on which plants (wheat, radish) are grown. Gas exchange in such a system consists of respiratory gas exchange of SLS and photosynthesis and respiration of plants. Specifics of gas exchange dynamics of high plants--SLS complex has been considered. Relationship between such a gas exchange and PAR irradiance and age of plants has been established. Nitrogen and iron were found to the first to limit plants' growth on SLS when process conditions are deranged. The SLS microflora has been found to have different kinds of ammonifying and denitrifying bacteria which is indicative of intensive transformation of nitrogen-containing compounds. The number of physiological groups of microorganisms in SLS was, on the whole, steady. As a result, organic substances--products of exchange of plants and microorganisms were not accumulated in the medium, but mineralized and assimilated by the biocenosis. Experiments showed that the developed model of a man-made ecosystem realized complete utilization of plant wastes and involved them into the intrasystem turnover.     

Sc在L10-TiAl金属间化合物中占位的理论研究

基于密度泛函理论,运用第一原理赝势平面波方法,采用CASTEP量子力学能量软件包研究了Sc占据Ti位与Sc占据A l位的超胞晶格常数、原子形成热、超胞总态密度与电子密度差分图,两种情况对比下,在L10-TiA l合金中,Sc优先占据Ti位,这一结论为进一步研究三元系TiA l-Sc合金提供了理论研究的基础。     

提高电铸局部电沉积速率试验研究

电铸成型是采用离子沉积的方法制造复制件，具有很好的复制精度，因此电铸技术得到了广泛的应用。但由于受极限电流密度等多方面因素的影响，电铸速率一直是制约电铸技术发展的一个瓶颈，许多学者为此做了大量的理论和试验研究，但对如何提高极限电流密度还没有提供一个比较满意的答案，为提高电铸局部电沉积速率，本文在前人工作的基础上，讨论了影响电铸速率的因素，提出了一种新型的电铸方法－喷射式电铸，并通过两组试验分析了局部电沉积速率怀电铸液流量的关系以及局部铸速率与喷嘴口径的关系，试验结果表明，采用喷射式电铸可以大大提高局部极限电流密度，从而使电铸局部电沉积速率有一个较大范围的提高，为将电铸与快速成型结合奠定了试验基础。     

动态三角翼的非定常气动特性和压力分布相关研究

文章介绍了不同后掠角三角翼在进行俯仰振荡时的动态压力特性,说明这种动态压力特性同三角翼的法向力的变化是密切相关的,试验研究揭示了流态、压力和气动力之间的密切关系。同时试验研究显示三角翼上翼面压力的动态变化曲线呈现出双峰形态;不同后掠角三角翼在动态试验过程中压力、法向力都具有相似特性。     

Estimated Flight Time for Optimum Trajectories

Various methods are presented for estimating the flight time for vehicles which fly an optimum trajectory. A realistic example is considered in order to display the inherent accuracy of each of these methods. Numerical integration methods are found to be the most accurate. Simple formulas are derived for the case where a less accurate estimate is acceptable. All of these methods require less computation than would be required in order to solve the overall optimization problem. Thus any one of these methods can be applied to an onboard guidance scheme or control system which requires a real time estimate of the time-to-go.     

Recent developments in micrometeoroid simulation

In the first part the state of the art of the most advanced micrometeoroid simulation techniques is reviewed. Then a new accelerator is described, which was developed jointly by the Technische Universität München and the N.A.S.A. George C. Marshall Space Flight Center. Finally the use of this new technique is indicated for basic research in fields other than astronautics.