The high level waste (HLW) generated from the reprocessing of the spent fuel of pressurized heavy water reactor has been characterized for the minor actinides. The radiation dose of the waste solution was reduced by radiochemical separation of cesium from HLW by solvent extraction with chlorinated cobalt dicarbollide dissolved in 20% nitrobenzene in xylene. Minor actinides (Np, Pu, Am, Cm) in the high level waste were assayed by alpha spectrometry following radiochemical separation. The gross alpha activity determined by liquid scintillation agrees well (within 10%) with the cumulative quantities of actinides determined by alpha spectrometry. 相似文献
We study Lusztig?s t-analog of weight multiplicities, or affine Kostka–Foulkes polynomials, associated to level one representations of twisted affine Kac–Moody algebras. We obtain an explicit closed form expression for the unique t-string function, using constant term identities of Macdonald and Cherednik. This extends previous work on t-string functions for the untwisted simply-laced affine Kac–Moody algebras. 相似文献
A Bayesian data analysis technique is presented as a general tool for inverting linear viscoelastic models of branched polymers.
The proposed method takes rheological data of an unknown polymer sample as input and provides a distribution of compositions
and structures consistent with the rheology, as its output. It does so by converting the inverse problem of analytical rheology
into a sampling problem, using the idea of Bayesian inference. A Markov chain Monte Carlo method with delayed rejection is
proposed to sample the resulting posterior distribution. As an example, the method is applied to pure linear and star polymers
and linear–linear, star–star, and star–linear blends. It is able to (a) discriminate between pure and blend systems, (b) accurately
predict the composition of the mixtures, in the absence of degenerate solutions, and (c) describe multiple solutions, when
more than one possible combination of constituents is consistent with the rheology. 相似文献
Particles have been shown to adsorb at the interface between immiscible homopolymer melts and to affect the morphology of
blends of those homopolymers. We examined the effect of such interfacially active particles on the morphology of droplet/matrix
blends of model immiscible homopolymers. Experiments were conducted on blends of polydimethylsiloxane and 1,4-polyisoprene
blended in either a 20:80 or 80:20 weight ratio. The effects of three different particle types, fluoropolymer particles, iron
particles, and iron oxyhydroxide particles, all at a loading of 0.5 vol.%, were examined by rheology and by direct flow visualization.
Particles were found to significantly affect the strain recovery behavior of polymer blends, increasing or decreasing the
ultimate recovery, slowing down or accelerating the recovery kinetics, and changing the dependence of these parameters on
the applied stress prior to cessation of shear. These rheological observations were found to correlate reasonably well with
particle-induced changes in drop size. The particles can both increase as well as decrease the drop size, depending on the
particle type, as well as on which phase is continuous. The cases in which particles cause a decrease in drop size are analogous
to the particle stabilization of “Pickering emulsions” well-known from the literature on oil/water systems. We hypothesize
that cases in which particles increase drop size are analogous to the “bridging–dewetting” mechanism known in the aqueous
foam literature. 相似文献
Twisted marine cables on the sea floor can form highly contorted three-dimensional loops that resemble tangles. Such tangles or ‘hockles’ are topologically equivalent to the plectomenes that form in supercoiled DNA molecules. The dynamic evolution of these intertwined loops is studied herein using a computational rod model that explicitly accounts for dynamic self-contact. Numerical solutions are presented for an illustrative example of a long rod subjected to increasing twist at one end. The solutions reveal the dynamic evolution of the rod from an initially straight state, through a buckled state in the approximate form of a helix, through the dynamic collapse of this helix into a near-planar loop with one site of self-contact, and the subsequent intertwining of this loop with multiple sites of self-contact. This evolution is controlled by the dynamic conversion of torsional strain energy to bending strain energy or, alternatively, by the dynamic conversion of twist (Tw) to writhe (Wr). 相似文献
Ion-irradiation induced surface stress generation and the resulting deflection of 2D cantilever graphene films is studied using molecular dynamics (MD) simulations. The simulation results show that the free-end deflection is strongly dependent on the kinetic energy of the incident ions. At low incident energies (?10 eV), the graphene film bends towards the irradiated side (upward deflection in our simulations); a transition from bending towards the irradiated side (upward deflection) to bending away from the irradiated side (downward deflection) occurs when the incident energy is ~10 eV; the downward deflection peaks at ~50 eV. Further increases of the incident energy cause the magnitude of downward deflection to decrease. The evolution of free-end deflection with respect to the number of incidences is also dependent on the incident energy. The dependence of the deflection behavior of the graphene films on the incident energy revealed by our atomistic simulations suggests the generation of intrinsic stress of different levels in the growing films. Such behavior may be attributed to competing mechanisms of production and annihilation of interstitial- and vacancy-like defects in the growing film. Understanding the dependence of thin film deflection on the incident energy provides guidelines for controlling thin film shapes at the nanometer scale using ion-beam machining. 相似文献
Extraction of Np4+ and \( {\text{NpO}}_{2}^{2 + } \) was carried out from nitric acid feeds using solutions of N,N,N′,N′-tetra-n-octyldiglycolamide (TODGA) in two imidazolium-based room temperature ionic liquids, viz., 1-butyl-3-methylimidazolium bis(trifluoromethanesulphonyl) imide ([C4mim][NTf2]) and 1-octyl-3-methylimidazolium bis(trifluoromethanesulphonyl) imide ([C8mim][NTf2]). The extraction equilibrium was attained within 2 h for both the metal ions in both the ionic liquids. While a cation exchange mechanism is proposed for the extraction of \( {\text{NpO}}_{2}^{2 + } , \) an ion-pair mechanism of extraction is proposed for the Np4+ ion. The nature of the extracted species was determined by carrying out experiments at varying concentrations of TODGA, and species of the type Np(L)2(NO3)4 and NpO2(L)2+ were found to be extracted in 3 mol·dm?3 HNO3. The identification of these extracted species was also supported from the variable nitrate and C4mim+ ion concentration experiments. 相似文献
Operations research (OR) has been at the core of decision making since World War II, and today, business interactions on different platforms have changed business dynamics, introducing a high degree of uncertainty. To have a sustainable vision of their business, firms need to have a suitable decision-making process at each stage, including minute details. Our study reviews and investigates the existing research in the field of decision support systems (DSSs) and how artificial intelligence (AI) capabilities have been integrated into OR. The findings of our review show how AI has contributed to decision making in the operations research field. This review presents synergies, differences, and overlaps in AI, DSSs, and OR. Furthermore, a clarification of the literature based on the approaches adopted to develop the DSS is presented along with the underlying theories. The classification has been primarily divided into two categories, i.e. theory building and application-based approaches, along with taxonomies based on the AI, DSS, and OR areas. In this review, past studies were calibrated according to prognostic capability, exploitation of large data sets, number of factors considered, development of learning capability, and validation in the decision-making framework. This paper presents gaps and future research opportunities concerning prediction and learning, decision making and optimization in view of intelligent decision making in today’s era of uncertainty. The theoretical and managerial implications are set forth in the discussion section justifying the research questions.
The electrochemical reduction of nitro group of orthonitroaniline (ONA) is carried out on Pb, Cu, and Sn electrodes. The effect
of current density, temperature, and acid concentration on product yield is studied. The polarization curve for ONA in acidic
condition is recorded. Under preparative electrolysis, ONA gives a mixture of hydroxylamine and phenylenediamine, the proportion
of phenylenediamine increasing with the electrolysis time. The product formation is confirmed by thin-layer chromatography,
melting-point test, UV-visible, IR, and NMR methods. The operating conditions are optimized for a good yield of orthophenylenediamine.
The catalytic activity of different metals for the reduction of nitro group is discussed. The percent yield of orthophenylenediamine
is found to be high on the lead electrode.
Published in Russian in Elektrokhimiya, 2007, Vol. 43, No. 2, pp. 215–221.
The text was submitted by the authors in English. 相似文献