Source-model technique analysis of electromagnetic scattering by surface grooves and slits

A computational tool, based on the source-model technique (SMT), for analysis of electromagnetic wave scattering by surface grooves and slits is presented. The idea is to use a superposition of the solution of the unperturbed problem and local corrections in the groove/slit region (the grooves and slits are treated as perturbations). In this manner, the solution is obtained in a much faster way than solving the original problem. The proposed solution is applied to problems of grooves and slits in otherwise planar or periodic surfaces. Grooves and slits of various shapes, both smooth ones as well as ones with edges, empty or filled with dielectric material, are considered. The obtained results are verified against previously published data.     

Calibrating Gruneisen-Gamma(V) in the Framework of the Adiabatic-Gamma(V) EOS for Detonation Products

In a previous article a new equation of state (EOS) for detonation products called adiabatic-gamma(V) was presented [1 Partom , Y. 2011 . Detonation products EOS by specifying gamma(V) for the principal isentrope . Journal of Energetic Materials , 29 ( 3 ): 193 – 208 .[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]]. Briefly, adiabatic-gamma(V) is a Gruneisen EOS referred to a principal isentrope, which is specified in terms of the adiabatic gamma γ(V). The γ(V) function is piecewise linear with an arbitrary number of nodes n ≥ 3. The nodes of γ(V) are calibrated from Chapman-Jouguet (CJ) conditions and from expanding cylinder test data. In an expanding cylinder test the products release along the principal isentrope. It is therefore possible to calibrate the Gruneisen parameter Γ from such a test only at the CJ point and at large V, and in between we assume a linear variation. Here we show that in a plate push test with a gap between the explosive and the plate the products release along a higher isentrope (in the PV plane), which makes it possible to calibrate Γ(V). We define Γ(V) as a piecewise linear curve with nodes at the same values of V as γ(V). We demonstrate a procedure for calibrating Γ(V) by matching a target velocity history u(t), to be obtained from a plate push test with a gap. Like the procedure for calibrating γ(V) demonstrated in [1 Partom , Y. 2011 . Detonation products EOS by specifying gamma(V) for the principal isentrope . Journal of Energetic Materials , 29 ( 3 ): 193 – 208 .[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]], this, too, is a recursive procedure.     

A suite of prototype CAD tools to support early phases of architectural design

A suite of prototype CAD (computer-aided design) tools has been developed as part of an educational experiment in which an architectural design studio course was combined with a computer science graduate course on architectural CAD to study the collaboration between architects and their clients in a computer-based environment. The suite of tools is based on formalized abstractions inspired by lessons learned in the VLSI (very large-scale integrated circuit) CAD revolution of the 1980s. It encourages a step-by-step transformation of a building program, first into symbolic representations that can be checked and evaluated with automated programs, and eventually into simple but consistent 3-D (three-dimensional) geometry that can be inspected with an interactive walk-through visualization program.     

Modulation of learning, pain thresholds, and thermoregulation in the rat by preparations of free purified alpha-linolenic and linoleic acids: determination of the optimal omega 3-to-omega 6 ratio

Ingested polyunsaturated fatty acids are postulated to lead to changes in central nervous system activity, presumably by altering the lipid composition of neuronal membranes. In support of this hypothesis, we and other investigators have previously demonstrated cognitive effects in rats fed oils that contain both alpha-linolenic acid (18:3 omega 3) and linoleic acid (18:2 omega 6), with the relative content of alpha-linolenic acid being seen as the critical variable. The present study in rats examined the effects of preparations containing different ratios of highly purified free alpha-linolenic acid to linoleic acid (about 25 mg/kg of body weight daily) on learning performance (Morris water tank), pain thresholds (heated plate), and thermoregulatory control of d-amphetamine-induced hypothermia during 4 weeks of treatment. Preparations with omega 3-to-omega 6 ratios ranging from 1:3.5 to 1:5 (specifically a ratio of 1:4) produced significant favorable effects on all of these variables. Although the specific mode of action remains to be elucidated, these results suggest that such preparations of free fatty acids should be evaluated in the treatment of memory disorders and pain conditions.     

On the Feasibility of Extending Oblivious Transfer

Oblivious transfer is one of the most basic and important building blocks in cryptography. As such, understanding its cost is of prime importance. Beaver (in: The 28th STOC, pp 479–488, 1996) showed that it is possible to obtain \(\mathsf{poly}(n)\) oblivious transfers given only n actual oblivious transfer calls and using one-way functions, where n is the security parameter. In addition, he showed that it is impossible to extend oblivious transfer information theoretically. The notion of extending oblivious transfer is important theoretically (to understand the complexity of computing this primitive) and practically (since oblivious transfers can be expensive and thus extending them using only one-way functions is very attractive). Despite its importance, very little is known about the feasibility of extending oblivious transfer, beyond the fact that it is impossible information theoretically. Specifically, it is not known whether or not one-way functions are actually necessary for extending oblivious transfer, whether or not it is possible to extend oblivious transfers with adaptive security, and whether or not it is possible to extend oblivious transfers when starting with \(O(\log n)\) oblivious transfers. In this paper, we address these questions and provide almost complete answers to all of them. We show that the existence of any oblivious transfer extension protocol with security for static semi-honest adversaries implies one-way functions, that an oblivious transfer extension protocol with adaptive security implies oblivious transfer with static security, and that the existence of an oblivious transfer extension protocol from only \(O(\log n)\) oblivious transfers implies oblivious transfer itself.     

Microwave Discharge of O2 and CO2 as a Synthetic Tool for Oxidations of Unsaturated Compounds Adsorbed on Solid Supports

Cis and trans stilbene, styrene, 1-decene and 6-dodecene adsorbed on silica gel were reacted with oxygen atoms produced by microwave discharge of O₂ and CO₂. At 0°C these compounds gave mainly epoxides and carbonyl compounds as in neat liquid reactions. Below — 60°C ozonolysis products were formed; cis and trans stilbene and styrene gave benzaldehyde while 1-decene and 6-dodecene resulted mainly in ozonides.     

A theory of roll coating of viscous and viscoelastic fluids

A theory for roll coating of a fluid onto a moving sheet is developed utilizing the usual “lubrication approximations.” The effects of fluid and operating parameters on coating thickness and pressure distribution are determined for a Newtonian fluid, and for a purely viscous non-Newtonian fluid obeying the Power Law. The results for these cases are obtained analytically, and are rather straightforward. A viscoelastic fluid is considered, of a type which shows typical non-Newtonian shear behavior observed in polymer melts and solutions and which also exhibits normal stress behavior. Analytical solutions are not possible, but a perturbation method, using a viscoelastic perturbation parameter related to a Deborah number, yields an approximate solution. Only terms to first order in the perturbation parameter are given. Subject to that degree of approximation, the following conclusions are drawn:

• 1 Non-Newtonian shear behavior reduces the pressure distribution, and increases the coating thickness.
• 1 Elasticity of the type usually observed in polymer solutions makes only a minor contribution to the roll-separating (load-carrying) force. The contribution is positive, but smaller than the corresponding negative contribution due to the non-Newtonian shear effects.
• 1 An increase in load-carrying capacity would require a different viscoelastic fluid than the type considered here—one that is essentially Newtonian in shear but, independently, capable of developing significant normal stresses.

     

Blade-coating of a viscoelastic fluid

A theory is presented which describes the dynamics of blade-coating of a viscoelstic fluid onto a moving sheet. The method begins with the usual “lubrication” approximation, and develops the solution as a perturbation about the Newtonian case. Viscoelasticity is described by an empirical constitutive equation which shows non-Newtonian viscosity and finite normal stress behavior consistent with typical observations of polymeric fluids. Theoretical results indicate a small increase in coating thickness due to departure from Newtonian behavior, and a significant decrease in the magnitude of the pressure developed under the blade. Consequently, the blade loading can be reduced significantly by viscoelastic effects. The results for the loading may be an artifact of the specific constitutive model, since it can be shown that some viscoelastic fluids, specifically an “elastic Newtonian” fluid, would exhibit increased loading relative to the inelastic Newtonian case.