Verbal communication and noise in eating establishments

A new simple prediction model has been derived for the average A-weighted noise level due to many people speaking in a room with assumed diffuse sound field. Due to the feed-back influence of noise on the speech level (the Lombard effect), the speech level increases in noisy environments, and the suggested prediction model gives a 6 dB reduction of the noise level by doubling the equivalent absorption area of the room. This is in contrast to the lowering by 3 dB by doubling of the absorption area for a constant power sound source. The prediction model is verified by experimental data found in the literature. In order to achieve acceptable conditions for speech communication within a small group of people, a guide for the recommended minimum absorption area per person in eating establishments is provided.     

Measurement and prediction of speech and noise levels and the Lombard effect in eating establishments

Measurements made of the acoustical characteristics of, and occupied noise levels in, ten eating establishments are described. Levels to which diners and employees were exposed varied from 45 to 82 dB(A). From these levels and diner questionnaire responses, the number of customers present and average noise levels to which individual diners were exposed during their visits were estimated. These data, assumptions about the number of talkers per customer, and classical room-acoustical theory were used to deduce talker voice output levels. These varied from slightly above "casual" to "loud." An iterative model for predicting speech and noise levels in eating establishments, including the Lombard effect as described by a new, proposed model, was developed. With the measured noise levels as the target for prediction, optimization techniques were used to find best estimates of unknown prediction parameters--such as those defining the Lombard effect, the number of talkers per customer, and the average absorption per customer--with highly credible results. The prediction algorithm and optimal parameters constitute a novel model for predicting speech and noise levels--and thus speech intelligibility--in eating establishments, as a function of the number of customers, including a proven, realistic model of the Lombard effect.     

Modeling of optimal conditions for oxyhemoglobin photodissociation in laser-irradiated biotissue

Based on the theory of radiation transfer and a model that describes the structure and optical properties of biotissues, we have found spectral conditions of irradiation of the skin surface that ensure efficient generation of molecular oxygen O₂ in the dermis due to the photodissociation of blood oxyhemoglobin. We show that, for maximal local O₂ formation at depths z ≤ 0.2 mm, 0.2 mm < z ≤ 0.9 mm, 0.9 mm < z ≤ 2.5 mm, and z > 2.5 mm, it is more effective to use wavelengths in the intervals 418 ± 5, 575 ± 5, 585 ± 5, and 600 ± 5 nm, respectively. Physical reasons for the shift of optimal wavelengths toward the red range of the spectrum are described. We show that they are based on the selectivity of optical properties of the skin biotissue, which acts as of a kind of spectral filter the transmission curve of which depends on the depth. It is found that irradiation at a wavelength near 575 nm is optimal for the generation of a maximal amount of O₂ in the intire bulk of the dermis.     

Ray-tracing prediction of optimal conditions for speech in realistic classrooms

Recent papers have discussed the optimal reverberation times in classrooms for speech intelligibility, based on the assumption of a diffuse sound field. Here this question was investigated for more ‘typical’ classrooms with non-diffuse sound fields. A ray-tracing model was modified to predict speech-intelligibility metric U₅₀. It was used to predict U₅₀ in various classroom configurations for various values of the room absorption, allowing the optimal absorption (that predicting the highest U₅₀)—and the corresponding optimal reverberation time—to be identified in each case. The range of absorptions and reverberation times corresponding to high speech intelligibility were also predicted in each case. Optimal reverberation times were also predicted from the optimal surface-absorption coefficients using Sabine and Eyring versions of diffuse-field theory, and using the diffuse-field expression of Hodgson and Nosal. In order to validate the ray-tracing model, predictions were made for three classrooms with highly diffuse sound fields; these were compared to values obtained by the diffuse-field models, with good agreement. The methods were then applied to three ‘typical’ classrooms with non-diffuse fields. Optimal reverberation times increased with room volume and noise level to over 1 s. The accuracy of the Hodgson and Nosal expression varied with classroom size and noise level. The optimal average surface-absorption coefficients varied from 0.19 to 0.83 in the different classroom configurations tested. High speech intelligibility was, in general, predicted for a wide range of coefficients, but could not be obtained in a large, noisy classroom.     

Choice of optimal conditions in electromagnetic analysis

A theoretical study is presented for alternating magnetic fields in a sphere and a long cylinder; this is extended to frequencies such that differences in diameter and surface conductivity are not distinguished in Förster's method. Optimal conditions for structural testing of the entire cross-section are found to occur in the audiofrequency range. Tables are given for the second derivatives of the real and imaginary components of the Bessel and McDonald functions.     

Computer program for determining optimal running conditions of a steam turbine cogeneration system

Cogeneration is an efficient way of using energy and at a national level permits an important saving in primary energy. Different systems include those with a back-pressure steam turbine and those with a pass-out condensing steam turbine.This paper deals with the basis and structure of a software pack that enables the user to determine the optimal running conditions in either case. The program is interactive, written in FORTRAN 77 and composed of six program blocks. Each block is responsible for one basic aspect of the analysis process.Because the objective function is non-linear and only point values are available, instead of algebraic expressions, the complex optimization algorithm is used. The object of the function is to minimize the hourly fuel and electricity costs during operation.Finally, the program has been applied to a cogeneration installation with a 970 kW back-pressure turbine. The results indicate that the system sometimes produces more steam per hour than required, the excess being due to the fact that the profit from the sale of electricity is greater than the cost of steam production.     

On publication characteristics of research establishments

Patterns of publication output, multiple authorship and individual productivity are measured for three physics institutions. The findings are compared with earlier results on publication rates in journals and some other research laboratories.     

任意椭圆偏振激光场非线性汤姆逊散射的一般表述与X射线产生的优化条件

基于相对论条件的电动力学,解析求解了任意椭圆偏振条件下激光场的非线性汤姆逊散射的一般表示.利用解析结果得到了背向非线性汤姆逊散射高次谐波的极值条件.结果表明对于基频背向汤姆逊散射,在相同条件下,圆偏振激光具有最大值而线偏振是最小值,如果激光偏振态从圆偏振连续的过渡到线偏振,背向汤姆逊散射的角功率随之单调递减.这一效应对高强度入射激光尤为重要,当 a² >5时,圆偏振情形的贡献几乎是线偏振的2倍.这对基于汤姆逊散射机制的X射线源实验研究具有重要参考意义. 关键词： 非线性汤姆逊散射 偏振度 极值     

Choice of optimal conditions for X‐ray fluorescence analysis of milk products with varying fat content

The design of experiments was used to study sources of errors in the sample preparation and to choose optimal conditions for X‐ray fluorescence (XRF) analysis of milk products of varying fat content. The measurements were performed using the conventional wavelength‐dispersive XRF (WDXRF) and the total reflection XRF (TXRF) techniques. For WDXRF, the dried milk samples were pelletized, and the mathematical models were constructed, which described the dependence of XRF intensity on the pelletizing pressure, the pellet weight and the milk fat content. The effect of radiation time on the stability of pressed milk powder samples was also estimated. When applying TXRF, the sample preparation involved diluting milk samples with the ultrapure water, adding the internal standard (Ga) and drying of a sample aliquot on a quartz glass sample carrier. The mathematical models were designed, which described the dependence of the sample preparation error on the dilution ratio and sample aliquot pipetted on the carrier. A physical interpretation of the obtained mathematical models was proposed. Copyright © 2013 John Wiley & Sons, Ltd.     

Quantitative EPR — Sensitivity to experimental conditions and optimal setting of recording parameters

This is the proportionality of the area under undistorted absorption curve to the spin number contributing to the resonance phenomena which makes the electron paramagnetic resonance spectrometry a method of quantitative analysis. However, quantitative EPR (Q-EPR) is not so simple as the relation is. Direct quantitative measurements are practically excluded, the comparison of both standard and unknown sample EPR signals (indirect determination) is rather used, as a rule. The accuracy of spin number determination is an essential problem of quantitative EPR. The experimental conditions and instrumental variables influencing the signal shape and intensity may lower the accuracy of quantitative determinations. There is different sensitivity of various line parameters to the instrumental distortions and experimental conditions. Thus, the optimal setting of instrumental variables controlling the distortions depends on the procedure being used for quantitative determinations. The aspects of sensitivity of different Q-EPR procedures to instrumental distortions, as well as the rules of optimal setting of these parameters are the subject of this review.     

An optimal analytical expression for the superparamagnetic relaxation rate under conditions of a stochastic resonance for the model of bistable systems

An analytical expression for the superparamagnetic relaxation rate of uniaxial particles modulated by a radio-frequency field is chosen that describes adequately the magnetic moment dynamics under conditions of a stochastic resonance in the approximation of discrete orientations. The complex magnetic susceptibility components are calculated for a weak external variable field. A comparison is made with the results of numerical modeling based on a solution of the Fokker-Planck equation with a periodic drift term. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 54–58, May, 2007.     

Prediction and validation of ash sticking probability under fouling conditions in pulverized coal combustion

Under the fouling conditions in stationary coal combustion systems, the sticking/rebound behavior of solid incident particles is a key issue in determining the ash deposition rate. From a dynamic point of view, the bulk fly ash, which dominants the deposited mass, successively interacts with the clean tube, the inner fine deposited layer and the bulk deposited layer during ash deposition. In this paper, we experimentally investigate the time-resolved evolution of ash fouling in a 25 kW coal combustor. The deposited mass flux rapidly reaches a stable state that fluctuates around a mean value of ～3 g/(m²·s) for two kind of probe materials. The rapid initial stage only allows the formation of 1–2 layers of bulk deposited ash, revealing the dominant role of bulk deposit in capturing large incident particles. Inspired by the observation, we apply a 3D adhesive discrete element model (DEM) to fully describe the many-body evolving process subject to the incident events of a 30-µm particle. The simulation agrees well with the experiments when using a higher particle surface energy of 200 mJ/m². The rapidly growing feature of ash sticking probability with increasing the bulk deposit layers can be reproduced in this case, and an empirical formula is proposed. It is also validated that, at the deposit growth stage, the newly-deposited particles stay just where they impact. The effectiveness of the DEM tool shall benefit a fully-validated sticking/rebound model under the fouling condition that is convenient for CFD use.     

Prediction of total loss factors of structures Part III: Effective loss factors in quasi-transient conditions

Previous work has been done on the prediction of the total loss factors of structures in steady state [1]. In this paper, the effective loss factors of coupled structures in quasi-transient conditions are considered, which are thought to be important parameters in the prediction of ringing noise radiated from impacting machines. SEA is used and Maidanik's arguments [2] are re-examined in analysis and discussion. A series of measurements have been carried out on two coupled plates (i.e., a structure having two substructures) and a randomly chosen complicated structure. An equation derived from the two coupled substructures model is used to estimate the effective loss factors of the two coupled plates. Good agreement is obtained between the estimated and measured values.     

Identification of optimal ALD process conditions of Nd2O3 on Si by spectroscopic ellipsometry

Variable angle spectroscopic ellipsometry (VASE) is used to investigate the thickness and optical properties of Nd₂O₃ films deposited by atomic layer deposition (ALD) at various process conditions. It is found that the films exhibit good thickness uniformity and an almost constant growth rate of 0.42 ?/cycle in the temperature region of 290–330 °C. Further examination of the imaginary part of the dielectric functions of the selected samples demonstrates that all optically observable dielectric-related defects are located in the interface layer between the silicon substrate and the native oxide rather than in the bulk Nd₂O₃ layer. And, the defects within the band gap of the interface are found to be strongly affected by the deposition temperature. In the deposition temperature range of 300–320 °C, only one absorption peak of 3.53 eV besides the silicon substrate’s critical features is observed, indicating that the Si/SiO₂/Nd₂O₃ stacks contain the fewest interfacial defects. Then the optimal ALD process condition for Nd₂O₃ is determined as Nd(thd)₃ (thd = 2,2,6,6,-tetramethyl-3,5-heptanedionato) evaporation temperature: 185 °C, deposition temperature: 300–320 °C, saturation condition: Nd(thd)₃ and pulse time longer than 0.5 s.