火花源原子发射光谱单次火花放电行为探讨

在火花源原子发射光谱中,光源的原子火花放电过程行为复杂,直接观测困难。为了研究原子在单次火花放电发光的行为,利用火花源原子发射光谱仪的时间解析功能和单次火花处理技术设计实验,获取不锈钢标准物质中铁、铝、硅、锰、磷、硫、碳等7个元素的原子在单次火花放电发光的光强随时间分布的时序曲线,通过对各个元素的单次火花光强随时间分布时序曲线的特征分析,得出了原子在单次火花激发过程中发光行为滞后于放电行为、不同元素的原子在同一激发条件下单次火花光强时序曲线的持续时间及发光的最高强度值的时间点存在差异的结论。这为降低火花源原子发射光谱仪的检出限、提高灵敏度以及避免元素间谱线干扰提供了新的途径,同时也为进一步研究火花放电过程中微观粒子的行为提供了新的途径。     

Gleeble—1500热／力模拟试验机高速压缩系统功能的改善

Ｇｌｅｅｂｌｅ－１５００热／力模拟试验机高速压缩系统经较长时间使用后，高速压缩性能达不到试验要求，经试验，在不更换相关组件的情况下，用修改给定程序曲线等办法，较好地解决了该问题。     

WA光学分析仪——光学液体分析专家

<正>全系列现场仪表专家Endress+Hauser,日前推出了WA光学分析仪系列产品。该系列产品可用于分析紫外吸收、色度、红外吸收、浊度、细胞生长,具有量程大、精度高、稳定性好等特点,可用于生命科学、食品饮料、化工、油气、水和污水等行业。该系列传感器采用光度测量原理。当光线照射到液面上,入射光强、透射光强、散射光强相互之间比值和水样特性之间存在一定的相关关系,通过测定透射光强,散射光强和入射光强     

炼钢电弧炉高功率变压器的低率使用

就炼钢电弧炉提高变压器功率后其供电曲线与节电之间的关系进行了系统分析，提出不同冶炼时期电弧热利用率不同，输入炉内的电功率也应随之进行调整。一座５ｔ炼钢电弧炉，通过改造使变压器扩容后，加之供电曲线选择适当，在其它条件相同下，单位电耗降低了１０４ｋＷ．ｈ／ｔ。     

炼钢电弧炉高功率变压器的低功率使用

就炼钢电弧炉提高变压器功率后其供电曲线与节电之间的关系进行了系统分析，提出不同冶炼时期电弧热利用率不同，输入炉内的电功率也应随之进行调整。一座５ｔ炼钢电弧炉，通过改造使变压器扩容后，加之供电曲线选择适当，在其它条件相同下，单位电耗降低了１０４ｋＷ·ｈ／ｔ。     

钕铁硼磁体磁性的近似普适规律的研究

为了探讨钕铁硼磁体磁性的近似普适规律,把不同性能钕铁硼磁体在各温度下的退磁曲线加以归一化,这使退磁曲线显示出近似的普适性,而且其内禀矫顽力及剩磁随温度变化的规律也相似,据此导出钕铁硼磁体在各温度下退磁曲线的近似普适数学表达式,由该公式计算得到的各温度下的退磁曲线与实测曲线基本吻合.     

取向硅钢磁化曲线的单矢量模型计算

采用单矢量模计算硅钢单晶不同的方向磁化曲线，给出了可以计算硅钢单晶任意方向磁化曲线的数值算法，在单矢量模型计算单昌磁化曲线的基础上，利用织构数据计算多晶硅钢任一方向的磁化曲线，结果较好地反映出磁化曲线随方向的变化趋势。     

定向凝固的半结晶硅及太阳电池的制备

定向凝固技术具有工艺简单、操作方便、生产效率较高等优点,能够降低太阳电池的成本。本文介绍了采用喷涂Si_3N_4粉的石英坩埚制备半结晶硅试验。以该晶体为基体材料,按常规工艺制备的太阳电池,在100毫瓦/厘米~2光强下,转换效率已达7.5％(面积为4厘米~2)和6.3％(面积为28.26厘米~2),光谱响应的峰值偏向于短波长方向,用作袖珍计算器的电源,在室内光强下有清晰的数字显示。     

磁制冷材料在不同温度下的M-H曲线测量方法及设备的研究

为了选择合适的磁制冷材料,得到材料的磁热效应,即ΔS-T曲线,必须测出材料在不同温度下的M-H曲线.我们采用脉冲磁场的方式提供测试所需的高磁场,自行研制了符合测试精度要求的M-H曲线测试装置,测试了金属Gd的-50℃～50℃之间的每隔10℃的不同温度下的M-H曲线.     

铝锂合金的超塑性m—δ曲线与CL方程式的应用

在不同的条件下，对２０９１Ａｌ－Ｌｉ合金的超塑性总延伸率δＦ和ｍ－δ曲线进行了测定。测到的总延伸率δＦ为４０７％。ｍ－δ曲线属ｍＬ－ｍｍａｘ型。分别呈基本形式、上升式及下降式三种形式。     

一类链路调度器的统一随机服务曲线研究

随着基于通信网络的业务应用不断的增加,已有的通信网络因所需负载的业务流种类的增加而需改进或提升服务性能。新设计出来的通信网络需为其所负载的业务数据流提供新的Qos服务保证．这要求寻找某种方法对计算机通信网络中的网络构成单元或其组合进行建模与性能保证分析。通信链路调度器网络构成单元对通信网络所能提供的Qos保证影响尤其突出．基于网络演算对这类通信网络构成单元及其组合进行服务保证分析,首先便是寻找这类网络构成单元的紧致性服务曲线。     

Effects of Hysteresis on Steady-State Infiltration in Unsaturated Slopes

Hysteresis is a common feature exhibited in hydraulic properties of an unsaturated soil. For a specific matric suction, water content or coefficient of permeability on a wetting curve is always lower than those found on a drying curve. This paper focuses on hysteresis observed in steady-state infiltration tests in a laboratory slope model. The slope model consisted of a 400 mm thick fine sand layer overlying a 200 mm thick gravelly sand layer at a slope angle of 30°. The slope model was subjected to artificial rainfalls of different intensities. The slope model was instrumented to continuously measure the changes in pore-water pressure or matric suction, volumetric water content, and water balance during an experiment. Two experiments with similar applied precipitation intensities were conducted on soils that experienced adsorption and desorption processes. For the adsorption process, the slope model was first subjected to an antecedent steady-state rainfall with an intensity lower than the intensity of the incident steady-state rainfall. In the adsorption process, the water content of the soils increased during the incident rainfall prior to achieving the steady-state condition. For the desorption process, the slope model was first subjected to an antecedent steady-state rainfall with an intensity higher than the intensity of the incident steady-state rainfall. In the desorption process, the water content of the soils actually decreased during the incident rainfall prior to achieving the steady-state condition. The results indicate that the matric suction distributions in soils experiencing the desorption process were higher than those observed in soils experiencing the adsorption process. The matric suctions within the slope during a steady-state infiltration were affected by the initial water content of the soil prior to the infiltration process. Numerical analyses, employing both drying and wetting hydraulic properties of the soils, were performed to study the difference in matric suctions as observed in the experiments. The results suggest that the hysteretic behavior of the soil affects the matric suction distribution within the slope at steady-state conditions. The appropriate hydraulic properties of the soils (i.e., drying or wetting) should be used in accordance with the process that the soils actually experience (i.e., desorption process or adsorption process) even though the slope is under a steady-state rainfall condition.     

Functional characteristics of lateral interactions between rods in the retina of the snapping turtle

1. Intracellular recordings were made of the slow hyperpolarizing light responses of single rods in the retina of the snapping turtle. Physiological criteria used to identify rods were verified by intracellular injections of Procion Yellow. 2. The amplitudes of the responses elicited by fixed intensity flashes increased as the stimulus was enlarged to a diameter of 300 mum. Scattered light was found incapable of accounting for this effect, which must result from summative interaction of rods with neighbouring receptors. Effects of summative interaction were observed even at stimulus intensities that produced maximal responses. Enlarging the diameter of the higher intensity stimuli from 100 to 300 mum increased the peak response amplitude by almost 50%; it also produced a distinct initial peak of the response which we term overshoot. The amplitude of this overshoot was graded with stimulus size. 3. Complete intensity-response relationships were determined using stimulus diameters of 100 and 750 mum for each rod. With the smaller stimulus the intensity response range was 4-5 log units, and with the larger stimulus this was increased to 5-0 log units. For intensities below about 60 quanta/mum2 per flash (514 nm) the amplitudes elicited by the large stimulus followed a sigmoid-shaped curve. However, at higher intensities an additional lobe appeared on the intensity-response relationship. The appearance of this lobe correlated with the emergence of the overshoot on the response wave form. 4. Determinations of rod flash sensitivity (mV per quantum per mum2) showed that it increased with stimulus size up to a stimulus diameter of about 300 mum. With diameters between 50 and 150 mum, a linear relationship existed between the flash sensitivity and stimulus area. Absolute quantal sensitivities increased with stimulus area by a factor of 26, from a value of 28 muV per photoisomerization per rod with a stimulus 25 mum in diameter, to 720 muV per photoisomerization per rod with a stimulus 300 mum in diameter. 5. By comparison, red-sensitive cones showed increased sensitivity as a function of stimulus size only up to a stimulus diameter of 120 mum. Their over-all sensitivity was lower than that of rods and proved linear with stimulus diameter rather than with stimulus area. 6. Simultaneous recordings were made from rod-cone pairs to determine whether the overshoot, and hence the lobe on the amplitude-intensity function, could result from a cone input to the rod response. The time course of the cone response proved much too rapid to fit the overshoot of the rod response. 7. The spectral sensitivity of the dark-adapted rod response closely followed the difference spectrum of the rod photopigment for wave-lengths greater than 450 nm. This was true throughout the intensity range of the response, including low intensities where response averaging was necessary. 8. At low response amplitudes (approximately 1 mV), about 70% of the 40 rods tested showed responses to long wave-length stimuli consisting of two components...     

Selection of Gravity Separators for the Beneficiation of the Uljin Tin Ore

Gravity separation is typically used in the beneficiation of tin ores as the density difference between the valuable and associated gangue minerals is significant. In the present investigation, a cassiterite sample collected from the Uljin deposit in South Korea has been subjected to different gravity separators to evaluate the separation efficiency. The selection of gravity units has been made based on performance evaluation following heavy liquid separation and assessment of grade/recovery curves and Tromp curve methods. In addition, a gravity separation index (GSI) has been proposed that is simpler than other methods for assessing the performance of gravity separators.     

Model for the fluorescence induction curve of photoinhibited thylakoids

The fluorescence induction curve of photoinhibited thylakoids measured in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethyl urea was modeled using an extension of the model of Lavergne and Trissl (Biophys. J. 68:2474-2492), which takes into account the reversible exciton trapping by photosystem II (PSII) reaction centers and exciton exchange between PSII units. The model of Trissl and Lavergne was modified by assuming that PSII consists of photosynthetically active and photoinhibited (inactive in oxygen evolution) units and that the inactive PSII units can efficiently dissipate energy even if they still retain the capacity for the charge separation reaction. Comparison of theoretical and experimental fluorescence induction curves of thylakoids, which had been subjected to strong light in the presence of the uncoupler nigericin, suggests connectivity between the photoinhibited and active PSII units. The model predicts that photoinhibition lowers the yield of radical pair formation in the remaining active PSII centers. However, the kinetics of PSII inactivation in nigericin-treated thylakoids upon exposure to photoinhibitory light ranging from 185 to 2650 micromol photons m-2 s-1 was strictly exponential. This may suggest that photoinhibition occurs independently of the primary electron transfer reactions of PSII or that increased production of harmful substances by photoinhibited PSII units compensates for the protection afforded by the quenching of excitation energy in photoinhibited centers.     

基于高斯函数的风机特性曲线拟合及应用

针对矿山风机特性曲线多项式拟合中存在的曲线振荡和假收敛,拟合的曲线与实际通风机特性曲线的非稳定工作区域形状相差较大等问题,基于最小二乘准则,提出一种用高斯拓展函数拟合风机p-Q曲线的算法。在计算过程中运用MATLAB软件对风机p-Q实测数据进行处理,利用BFS法编程计算了高斯非线性方程组并得到高斯函数各项参数,绘制了高斯拟合结果图,从而给出了求解最佳风机p-Q曲线拟合方程的算法。采用高斯函数可近似拟合包含马鞍形区域与稳定工作区域的风机全压特性曲线,与多项式最小二乘法相比,避免了低次多项式假收敛和高次多项式曲线振荡的问题。     

Luminescence properties of a new yellow long-lasting phosphorescence phosphor NaAlSiO_4:Eu~(2+),Ho~(3+)

A new aluminosilicate long-lasting phosphor with composition of NaAlSiO4:Eu2+,Ho3+ was synthesized and investigated. Under UV light excitation, the phosphor emitted yellow light corresponding to the characteristic emission of Eu2+ due to 5d-4f transition. Bright yellow phosphorescence sustaining for more than 30 min was observed after ceasing the excitation. The phosphorescence intensity decay obeyed a t–1 decay law, indicating a tunneling electron-hole recombination process in the phosphor. Four peaks appeared in the thermoluminescence curve and the ones at 322 and 370 K were thought to account for the long lasting phosphorescence at room temperature. The Ho3+ ion incorporated into the phosphor did not give any light but dramatically increased the intensities of both photoluminescence and phosphorescence via promoting defect levels in the phosphor.     

The effects of light intensity on hatching of Echinostoma caproni Miracidia

Egg cultures of Echinostoma caproni were exposed to 25-W incandescent light at control intensities (9.7 mumol s-1 m-2) and reduced intensities (1.0, 0.5, 0.25, 0.125, 0.06, 0.03, and 0.01 mumol s-1 m-2). Low intensities of light did not affect the diurnal hatching rhythm of the miracidia, with maximum hatching occurring from 1200 to 1300 hr. However, at 0.5, 0.25, and 0.125 mumol s-1 m-2, hatching was delayed 2 days at each interval. From 0.06 to 0.01 mumol s-1 m-2, hatching still occurred, but at 17 days of development rather than at the 11.3-day average found under illumination with a 25-W incandescent light. No appreciable hatching was observed in cultures kept in the dark.     

Management of spinal trauma

The objective of the study was to evaluate the relationship between curing light intensity and (1) linear post-gel polymerization contraction strain, and (2) degree of conversion of a dental composite. Cylindrical specimens of a dental resin composite were cured from a distance of 7 mm for 40 s at four attenuated light intensities (71%, 49%, and 34% of control intensity and for 20 s at 71% plus 20 s at 100% intensity). A group cured at full intensity served as a control. Degree of conversion (DC) was measured at the top and bottom and linear contraction strain was measured at the bottom of the composite samples. DC at the sample top was significantly different (P < 0.05) between all groups except the 71% and 49% intensity groups. At the sample bottom, DC resulting from the two highest intensities (71% and 100%) were not significantly different from each other (P > 0.05). All other groups were significantly different from each other (P < 0.05). DC for the sample cured at two light intensities was not significantly different from those cured at the lower intensity or higher intensity for 40 s (P > 0.05). The sample cured with two intensities showed a 21.8% reduction from the contraction strain predicted by a light energy density calculation. Application of light at less than the maximum intensity of the curing light resulted in significant reduction of polymerization contraction strain without significantly affecting the degree of conversion.     

Visual sensitivity in the black-bellied tree duck (Dendrocygna autumnalis), a crepuscular species.

Produced visual adaptation curves for 3 black-bellied tree ducks using D. S. Blough's (1955) psychophysical tracking procedure. 2 scotopic curves from different preexposure light intensities and 1 photopic curve were generated. Nonlinear regression curves were then fit to the raw data. The mean scotopic thresholds did not differ significantly, but as expected, they were significantly lower than the mean photopic threshold. Time to the curves' asymptotes correlated with preexposure light intensity. Although the adaptation curves showed no distinct rod-cone "break," retinal histology revealed a duplex retina with a preponderance of rods, which reflects this species' crepuscular habits. Results are discussed in relation to the ecology of the species. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)