净化厂房的洁净度管理及节能运行实例

对生产量不断增加的净化车间洁净度，对失控采取措施，使车间的洁净度达到要求。在生产条件许可的情况下，改变空调运行的各项参数，达到节约大量电费的目的。     

Subpicosecond Domain Switching in Discrete Regions of Pb(Zr0.35Ti0.65)O3 Thick Films

The time dependence of the domain switching current density, J_sw(t), under pulsed voltages on a ferroelectric parallel‐plate capacitor is the consequence of region‐by‐region polarization reversals across the film. As the distributive coercive voltage of domain nucleation increases from zero to the maximum applied voltage during the capacitor charging time, J_sw(t) is proportional to the domain switching speed at each time. By transforming the spatially inhomogeneous domain nucleation distribution into a temporal distribution of coercive fields (E_c), a local lnJ_sw versus E_c^?1 plot is derived for each domain, following the Merz equation. This provides insight into the independent domain switching dynamics at different nucleation sites in Pb(Zr_0.35Ti_0.65)O₃ thick films over a large current range. Although the activation field of the slope of the lnJ_sw(t) versus E_c^?1 plot varies with film area and temperature, all the plots extrapolate to a single point (J₀, E₀) from which the ultimate domain switching current density of J₀ =1.4 × 10⁸ A cm^?2 at the highest field of E₀ = 0.20‐0.25 MV cm^?1 is derived. Unexpectedly, J₀ and E₀ are independent of the film thickness and area, after correction for a small interfacial‐layer effect. This analysis provides rigorous evidence for nucleation rate‐limited domain switching with a subpicosecond nucleation time and the relative unimportance of domain forward‐growth time across film thicknesses between 0.14 and 2 μm. This work paves the way to improve the efficiency of ferroelectric thick‐film functionality in electronic and optoelectronic devices with ultrafast clock rates.     

New neural method for bias dependent noise modelling of microwave transistors

A new method for accurate determination of noise parameters of microwave transistors for various bias conditions is proposed in this paper. The proposed model consists of a transistor empirical noise model (modification of Pospieszalski’s noise model) and two artificial neural networks. With the aim to avoid extraction of the empirical model parameters for each bias point, an artificial neural network is used to introduce bias-dependence of the equivalent circuit parameters. Accuracy of such bias-dependent model is further improved by using an additional neural network aimed to correct the noise parameters’ values. The proposed modeling approach is exemplified by modelling of a MESFET device in packaged form. The noise parameters obtained by the simulation agree well with the measured data.     

Effects of grain source and enzyme additive on site and extent of nutrient digestion in dairy cows

Four lactating, cannulated Holstein cows were used in a 4 x 4 Latin square design to investigate the effects of grain source and fibrolytic enzyme supplementation on ruminal fermentation, nutrient digestion in the rumen and in the intestine, and milk production. A 2 x 2 factorial arrangement was used; two grains (barley and hull-less barley) were combined with and without enzyme. The enzyme supplement (Pro-Mote; Biovance Technologies Inc., Omaha, NE) contained primarily cellulase and xylanase activities and was applied daily to the total mixed diet. Dry matter intake was not affected by diet, but starch intake was greatest when hull-less barley was fed. Starch from hull-less barley was more digestible in the rumen and in the total tract than was starch from barley, but opposite results occurred for fiber digestion, indicating that hull-less barley depressed fiber digestion. As a result, cows fed the hull-less barley diets tended to produce more milk with a higher milk lactose content than did cows fed the barley diets. Enzyme supplementation had minimal effects on ruminal digestion but increased nutrient digestibility in the total tract and the proportion of microbial N in nonammonia N. Consequently, cows fed diets supplemented with enzyme had a higher milk protein content and tended to produce more 4% fat-corrected milk than did control cows. These results indicate that the use of hull-less barley rather than barley increased the digestible energy intake of dairy cows, resulting in higher milk production. The use of a fibrolytic enzyme mixture enhanced feed digestibility and milk production.     

In vitro and in vivo determinations of sun protection factors of sunscreen lotions with octylmethoxycinnamate

The aim of this work was to evaluate the correlation between in vitro and in vivo determinations of sun protection factors (SPF) of sunscreen lotions containing the synthetic sunscreen octyl methoxycinnamate. Three sunscreen lotions containing either 2, 4.5 or 7.5% octyl methoxycinnamate were prepared. The in vitro SPFs of these sunscreen lotions were determined according to the spectrophotometric method of Mansur et al. The in vivo SPF values were determined according to the Food and Drug Administration (FDA) method. The results indicate that there was a good correlation between the in vitro and in vivo determinations for the sunscreen lotions examined.     

Combining mutations in the incoming and outgoing pheromone signal pathways causes a synergistic mating defect in Saccharomyces cerevisiae

Mating pheromones stimulate Saccharomyces cerevisiae yeast cells to form a pointed projection that becomes the site of cell fusion during conjugation. To investigate the role of mating projections, we screened for mutations that enhanced the weak mating defect of MAT a ste2‐T326 cells that are defective in forming pointed projections. These cells are also 10‐fold more sensitive to α‐factor pheromone because ste2‐T326 encodes truncated α‐factor receptors that are not regulated properly. Mutations in AXL1, STE6 and FUS3 were identified in the screen. AXL1 was studied further because it is required for efficient a ‐factor pheromone production and for selecting the site for bud morphogenesis. Mutation of AXL1 did not enhance the morphogenesis or pheromone sensitivity defects of ste2‐T326. Instead, the synergistic mating defect was apparently due to decreased a ‐factor production because the axl1Δ ste2‐T326 cells mated well with a sst2 α mating partner that is supersensitive to a ‐factor. When combined with a wild‐type mating partner, the ste2‐T326 axl1Δ cells failed to mate because they did not lock cell walls, one of the earliest steps in conjugation. Analysis of axl1Δ in combination with other mutations that cause defects in morphogenesis or pheromone sensitivity (e.g. bar1, sst2, afr1) indicated that both phenotypes of ste2‐T326 cells, supersensitivity to α‐factor and the defect in forming pointed projections, contributed to the synergistic mating defect. We suggest a model that the synergistic mating defect is caused by the combined effects of ste2‐T326 and axl1Δ on the presentation of a ‐factor to partner cells. Altogether, these results demonstrate an important linkage between the incoming and outgoing pheromone signals during the intercellular communication that promotes yeast mating. Copyright © 1999 John Wiley & Sons, Ltd.     

Effect of cultivar and seed maturity on amino acid content in fresh and canned broad bean (Vicia faba v. major)

The content of dry matter, total nitrogen, and amino acids (except for tryptophan) in fresh and canned broad bean (Vica fabav. major) seedswas determined, in the canned product whole seeds or cotyledons without hull being analysed. Two Dutch bred cultivars, Comprimo RS with large seeds and medium sized Threefoldwhite, were investigated at four stages of maturity defined by the content of dry matter at levels of about 25% (stage I), 30% (II), 35% (III), and 40% (IV). Amino acid content in 100 g fresh weight was similar in the two cultivars, rapidly increasing with maturation. The value of protein expressed by the EAA index was almost the same for the investigated cvs, usually being slightly higher in the case of more mature seeds. Whole seeds from canned product contained slightly less amino acids than the raw material while the EAA index showed similar or slightly lower values for whole seeds than for the raw vegetable. The content of all the amino acids (except for tyrosine) was greater and the EAA indices were higher in the cotyledons of canned broad bean than in whole seeds. Methionine with cystine were the limiting amino acids in fresh and canned seeds.     

基于正反HFM信号的水下高速小目标处理算法与试验分析

针对水下高速小目标的特点,提出了基于宽带正反双曲调频（HFM）信号的水下高速小目标检测与参数估计快速算法,并完成了仿真。通过在信号发射端加入时间伸缩因子来模拟目标运动,实现了水下高速小目标检测与参数估计的动态试验。并采集了雷体的反射回波数据。设计的以TMS320C6701为核心的信号处理系统,通过本文提出的快速算法实现了低信噪比下雷体反射回波检测与参数估计。试验结果表明,基于正反HFM信号的快速处理算法及数字信号处理（DSP）系统能有效完成低信噪比下的高速目标回波的检测与参数估计,与仿真结果具有较好的一致性．     

Analysis of Millimeter Wave Scattering by the Infinite Plane Metallic Grating Using PCG-FFT Technique

In this paper, both fast Fourier transformation (FFT) and preconditioned CG technique are introduced into method of lines (MOL) to further enhance the computational efficiency of this semi-analytic method. Electromagnetic wave scattering by an infinite plane metallic grating is used as the examples to describe its implementation. For arbitrary incident wave, Helmholz equation and boundary condition are first transformed into new ones so that the impedance matrix elements are calculated by FFT technique. As a result, this Topelitz impedance matrix only requires O(N) memory storage for the conjugate gradient FFT method to solve the current distribution with the computational complexity O(N log N) . Our numerical results show that circulate matrix preconditioner can speed up CG-FFT method to converge in much smaller CPU time than the banded matrix preconditioner.     

CAD of Millimeter Wave Y-Junction Circulators with a Ferrite Sphere

A gradient optimization technique along with a definition of cost function is applied to the CAD of the circulator with a magnetized ferrite sphere for millimeter wave communications. A three-dimensional Finite-Difference Time-Domain (FDTD) approach for the analysis of this ferrite sphere based microstrip circulator is presented. The topology of the structure is enforced at each step of optimization and its physical dimensions are used as optimization variables. The cost function is defined using location of zeros and poles of the circulator's transmission, isolation, and reflection functions. Numerical tests show that the optimization process converges from an arbitrarily selected starting point with the new definition of the cost function.