A spaceborne LFM scatterometer for ocean surface wind vectormeasurement-a time domain approach

The limitations of the currently used continuous-wave-pulse (CW-pulse) spaceborne scatterometers for wind-vector retrieval are reviewed. The disadvantages due to purely time-domain or frequency-domain (Doppler filtering) approaches are described. To overcome the limitations of these methods, a modified scheme is proposed wherein the pulse transmitted is linearly frequency modulated (LFM) and the processing is carried out in the time domain. This method is described and compared with other techniques to highlight the improved results obtainable with this LFM technique     

A step towards improvements in the characteristics of self excitedinduction generator

Improvements of voltage regulation characteristics of self-excited induction generators (SEIGs) are investigated. Typical results of the sensitivity studies performed are presented and conclusions are drawn to suggest guidelines for design of such generators     

Synthesis of algorithm-based fault-tolerant systems from dependencegraphs

Algorithm-based fault tolerance (ABFT) is a method for improving the reliability of parallel architectures used for computation-intensive tasks. A two-stage approach to the synthesis of ABFT systems is proposed. In the first stage, a system-level code is chosen to encode the data used in the algorithm. In the second stage, the optimal architecture to implement the scheme is chosen using dependence graphs. Dependence graphs are a graph-theoretic form of algorithm representation. The authors demonstrate that not all architectures are ideal for the implementation of a particular ABFT scheme. They propose new measures to characterize the fault tolerance capability of a system to better exploit the proposed synthesis method. Dependence graphs can also be used for the synthesis of ABFT schemes for non-linear problems. An example of a fault-tolerant median filter is provided to illustrate their utility for such problems     

Probabilistic cost estimation in advance of production in a computerized manufacturing system through stochastic geometric programming

A mathematical model for stochastic cost optimization has been developed. The model contains cost terms such as inventory cost, penalty cost for due date violation, and the machining cost. The probable range of cost has been estimated by a stochastic geometric program. If an exact solution is desired, a two stage stochastic geometric program has to be solved. This is mathematically tedious and requires great computational effort. However, managers are often concerned with a policy decision which can be based on the probable lower and upper bounds on the cost function. The probability level on the lower bound of cost has been calculated through the theory of error propagation. This approach is explained through an example.     

Storage stability of solid rocket fuels. 2. Effect of oxidizer loadings

Ageing behaviour, leading to ballistic changes, has been studied as a function of oxidizer loading in polystyrene/ammonium perchlorate solid-propellants. The ageing studies were carried out at 100 °C in air. Change in burning rate decreased as the oxidizer loading increased from 75 to 80%. The change in thermal decomposition rates both at 230 and 260 °C also decreased as the oxidizer loading in the propellants increased. The shapes of the plots of the changes in burning rate and thermal decomposition rate (230 and 260 °C) at different storage times for different oxidizer-loaded propellants seem to be exactly similar. These results lead to the conclusion that the thermal decomposition of the propellant may be responsible for bringing about the ballistic changes during the ageing process. Infrared studies of the binder portion of the aged propellant indicate that peroxide formation takes place during the course of ageing and that peroxide formation for a particular storage time and temperature increases as the loading decreases.     

Multidimensional high-throughput screening of displacers

A multidimensional, batch high-throughput screening (MD-HTS) protocol was developed to investigate the effects of various parameters on the selectivity of ion-exchange protein displacement systems. A variety of molecules were screened, and the results were employed to provided insights into the influence of displacer chemistry and concentration, resin chemistry, and mobile-phase salt counterion on the efficacy and selectivity of these nonlinear chromatographic systems. These results open up the possibility of tailoring the selectivity of displacement separations by choosing appropriate combinations of operating conditions using the MD-HTS technique. The screens were also employed for the identification of displacers and conditions for the separation of a challenging protein mixture by selective displacement chromatography. Column displacements were carried out with potential lead compounds identified from the MD-HTS screens, and the results confirmed that selective displacement could indeed be achieved for this model mixture. Furthermore, the results indicated that this approach is particularly useful when the order of elution is not changed, but the inherent selectivity is increased in the presence of the displacer. The results presented in this paper demonstrate the utility of the MD-HTS technique for rapid method development in protein ion-exchange displacement chromatography.