Indoor environments propagation simulation using a hybrid MoM and UTD electromagnetic method

Radio channel observation and characterization is indispensable in mobile communications systems development. Efficient propagation prediction is crucial for rapid and cost-effective systems deployment. On-site measurements, statistical models, propagation prediction and deterministic modeling are widely used for the qualification of radio channels. In this paper, a simulation tool for deterministic channel modeling in indoor environments is evolved. A hybrid combination of the Method-Of-Moments (MoM) and the Uniform Theory of Diffraction (Utd) is used. Statistical characteristics of a simple office room are calculated and the results are in excellent agreement with corresponding results of relative research on the field.     

Periprandial self-intravenous drinking in the rat.

Describes 4 experiments in which self-injected intravenous (iv) drinking (SID) of intact and desalivated male albino Wistar rats (N = 29) was studied over long periods in relationship with continuously recorded feeding of powdered chow. Periprandial episodes of SID were similar to those of oral drinkers, but the preprandial anticipatory component was increased in these permanently dehydrated (oliguric) Ss. The elimination of hedonic factors together with the observed responses to calorically or osmotically modified diets available ad lib or in restricted schedules (1 or 2 meals a day) emphasized the regulatory role of periprandial drinking. Ss that received injections in parallel with their SID-paired partners showed a nonreliable meal onset following iv water receipt; generally, meals remained taken in an idiosyncratic pattern. In the absence of food, SID Ss continued the rhythm of iv water ingestion. Results are discussed with reference to regulatory nature of drinking and to biological oscillator models. (34 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Recovery of uranium from phosphoric acid by means of supported liquid membranes

U(VI) was transported at 23 ± 1°C from 5–6 M phosphoric acid solutions through liquid membranes of kerosene solutions of di(2-ethylhexyl) phosphoric acid and trioctyl phosphine oxide (D2EHPA/TOPO) supported on porous polytetrafluoroethylene to a solution of phosphoric acid of equal or greater molarity containing ferrous ion as a reducing agent. The ferrous ion could be omitted when the higher molarity acid was used. The uranium flux was proportional to the U(VI) concentration. The overall resistivity of the membranes to uranium flux had a diffusional component that was proportional to the membrane thickness and an interfacial component that resulted from rate-limiting uranium complexation/decomplexation kinetics. The interfacial component accounted for over 80% of the resistivity of a membrane 75 μm thick. Increasing the temperature to 60°C only slightly diminished the interfacial resistivity. A theoretical model was constructed that accommodated data obtained from uranium transport through the membranes and through quiescent layers of phosphoric acid and D2EHPA/TOPO in kerosene. The average uranium flux from simulated solutions of wet-process phosphoric acid at 90% uranium transfer was estimated to be 1.3 × 10^?11 mol cm^?2 sec^?1, or 0.09 lb ft^?2 yr^?1. The flux was judged to be too low for supported liquid membranes to be competitive with liquid/liquid extraction for recovery of uranium from wet-process phosphoric acid.     

The cGMP-Dependent Protein Kinase 2 Contributes to Cone Photoreceptor Degeneration in the Cnga3-Deficient Mouse Model of Achromatopsia

Mutations in the CNGA3 gene, which encodes the A subunit of the cyclic guanosine monophosphate (cGMP)-gated cation channel in cone photoreceptor outer segments, cause total colour blindness, also referred to as achromatopsia. Cones lacking this channel protein are non-functional, accumulate high levels of the second messenger cGMP and degenerate over time after induction of ER stress. The cell death mechanisms that lead to loss of affected cones are only partially understood. Here, we explored the disease mechanisms in the Cnga3 knockout (KO) mouse model of achromatopsia. We found that another important effector of cGMP, the cGMP-dependent protein kinase 2 (Prkg2) is crucially involved in cGMP cytotoxicity of cones in Cnga3 KO mice. Virus-mediated knockdown or genetic ablation of Prkg2 in Cnga3 KO mice counteracted degeneration and preserved the number of cones. Analysis of markers of endoplasmic reticulum stress and unfolded protein response confirmed that induction of these processes in Cnga3 KO cones also depends on Prkg2. In conclusion, we identified Prkg2 as a novel key mediator of cone photoreceptor degeneration in achromatopsia. Our data suggest that this cGMP mediator could be a novel pharmacological target for future neuroprotective therapies.     

Design of Efficiently Encodable Rate-Compatible LDPC Codes Using Vandermonde Extension Matrices

A low-complexity algorithm for the design of efficiently-encodable rate-compatible (RC) low-density parity-check (LDPC) codes by deterministically extending an irregular repeat-accumulate (IRA) is introduced. The extending structure is based on circulants shifted according a truncated Vandermonde matrix (VM) and therefore termed as “extended VM” (eVM). The novel extending algorithm is significantly less computationally complex than other known similar methods since it does not require any optimization of the extending profile or any post-construction girth conditioning. To improve the codes’ properties and correcting capabilities in low code rate applications, the optimal proportions of degree-1 and degree-2 parity bits for the extended nodes are investigated and, in contrast to existing deterministic extending approaches for RC-IRA codes, an extending increment step equal to half the information block length is chosen. Various bit error rate (BER) and frame error rate (FER) have been obtained for different code rates, R, and information block length k ₀ = 512 and 1024 bits considering an additive white Gaussian noise (AWGN) channel. The results have demonstrated that the proposed eVM RC-LDPC codes, despite their very simple structure and very low computational complexity, exhibit excellent performance only slightly inferior to both dedicated IRA and previously known RC-IRA codes for different data block sizes.     

Efficient PCA-driven EAs and metamodel-assisted EAs,with applications in turbomachinery

This article presents methods to enhance the efficiency of Evolutionary Algorithms (EAs), particularly those assisted by surrogate evaluation models or metamodels. The gain in efficiency becomes important in applications related to industrial optimization problems with a great number of design variables. The development is based on the principal components analysis of the elite members of the evolving EA population, the outcome of which is used to guide the application of evolution operators and/or train dependable metamodels/artificial neural networks by reducing the number of sensory units. Regarding the latter, the metamodels are trained with less computing cost and yield more relevant objective function predictions. The proposed methods are applied to constrained, single- and two-objective optimization of thermal and hydraulic turbomachines.     

A novel rapid method for the determination of frying oil quality: development of prototype and equations and examination with respect to legislation criteria

The present work presents a prototype apparatus developed for a novel method based on capillary penetration for the determination of frying oil quality and examines the method and the performance of the prototype. The work further assesses the method results in comparison with the results of established methods and proposes equations for calculating frying oil quality parameters relevant to legislation criteria. The examination of the method is performed by using 184 oil samples produced by frying different foods in different oils for forty-five successive batches. Equations relating the method output with the total polar compounds, total polymers and viscosity are proposed. High correlation coefficients between legislation criteria and the method result are obtained: R² = 0.96, R² = 0.91 and R² = 0.86 for correlation with the oil viscosity, the polymer compounds and the TPC of the fried oils, respectively. The false-positive and false-negative answers of the method are below 2.5% for all cases.     

The role of phosphoric acid in the anodic electrocatalytic layer in high temperature PEM fuel cells

The poisoning effect and the role of H₃PO₄ (PA) at the anodic electrocatalytic layer of a high temperature polymer electrolyte membrane (HT PEM based on ADVENT TPS^®) fuel cell are discussed under the light of cyclic voltammetry, CO stripping, and X-ray photoelectron spectroscopy (XPS) experiments. The catalytic layer was based on both the pyridine-modified multi-wall carbon nanotubes, 30 wt% Pt/(ox.MWCNT)–Py, and on commercial 30 wt% Pt/C, with varying PA loadings on the electrode. At low PA loadings (<3 gPA/gPt), the electrochemically active surface area of Pt decreases significantly under H₂ anode long-term operation, approaching surface Pt utilization <10 %. This degradation is attributed to the formation of pyrophosphoric or triphosphoric acid as well as catalytically H₂ reduced PA species, which block the Pt surface area. As was explicitly detected by means of XPS PA species were displaced from the Pt surface under H₂ or CO exposure. The poisoning effect is reversible as these species can be hydrated back to orthophosphoric acid. The reduced species can be reoxidized into PA at 750 mV versus RHE. On the other hand, the electrochemical interface is stable at PA loadings exceeding 3 gPA/gPt, thus approaching Pt surface utilization >80 % in the long term. This is believed to be a consequence of the more uniform distribution of PA, thus eliminating the PA displacement from the Pt interphase. It is hypothesized that the minimization of the PA poisoning effect at PA > 3 gPA/gPt, may also be a result of more efficient hydration of the catalytic layer that is being achieved through the hydration of the PA in the membrane and in the catalyst layer by the cathodically produced water vapors.