Dynamic light scattering by gels under hydrostatic pressure

Measurements of variation with pressure of the collective diffusion constant D_c in polyacrylamide gels using both a good solvent (water) and a theta solvent (methanol 30% - water 70% by volume) are reported. From these observations the variation of ξ_h, the hydrodynamic screening length in the gel, is obtained, and compared with ξ_st, the static screening length. The latter is obtained from measurements of the density of the polymer solutions. In the concentration range studied (3%–10%) and for pressures up to 3 kbar, both ξ_h and ξ_st diminish with increasing pressure (i.e. the solvent quality improves), but the variation of ξ_h is more than an order of magnitude smaller than ξ_st for both the poor and good solvent cases.     

Functionalization of soluble polymers

Summary The synthesis of di-(4-formylphenyloxyethyl) poly(oxyethylene) and the corresponding oxime derivative are described. Kinetic aspects of the reaction of the dichloro telechelic with 4-hydroxy benzaldehyde are investigated and discussed.     

Sensitivity analysis of initial value problems with mixed odes and algebraic equations

An efficient method is described for sensitivity analysis of nonlinear initial value problems, which may include algebraic equations as well as ordinary differential equations.The linearity of the sensitivity equations is utilized to solve them directly via the local Jacobian of the state equations. The method is implemented with the implicit integrator DASSL and is demonstrated on a stiff industrial reaction model.     

Randomized unbiased design of regression experiments on functionals in a Hilbert space

Translated from Kibernetika, No. 2, pp. 58–66, March–April, 1991.     

Compile-time partitioning of iterative parallel loops to reducecache coherency traffic

Adaptive data partitioning (ADP) which reduces the execution time of parallel programs by reducing interprocessor communication for iterative parallel loops is discussed. It is shown that ADP can be integrated into a communication-reducing back end for existing parallelizing compilers or as part of a machine-specific partitioner for parallel programs. A multiprocessor model to analyze program execution factors that lead to interprocessor communication and a model for the iterative parallel loop to quantify communication patterns within a program are defined. A vector notation is chosen to quantify communication across a global data set. Communication parameters are computed by examining the indexes of array accesses and are adjusted to reflect the underlying system architecture by compensating for cache line sizes. These values are used to generate rectangular and hexagonal partitions that reduce interprocessor communication     

Processing of engineering ceramics with high power CO2 lasers

The hardness and brittleness of high performance engineering ceramics such as zirconia, aluminia, silicon carbide and silicon nitride makes traditional processing very expensive and time consuming. Efforts have been made to cut thick commercial ceramics with a continuous wave CO₂ laser. The results obtained so far are very promising and materials up to 10 mm in thickness have been cut successfully.     

Neutron and capture γ-ray accumulation factors in engineering calculations of reactor shielding

Translated from Atomnaya Énergiya, Vol. 66, No. 5, pp. 321–324, May, 1989.     

Analog regulators of the energy-liberation distribution in nuclear reactors

Translated from Atomnaya Énergiya, Vol. 66, No. 2, pp. 81–85, February, 1989.