Determination of tin in nonferrous metals

Curves are included showing the relationship between voltage and relative position of electrodes, and between voltage and counter gas pressure. Also included are experiments on the preparation of sensitive and insensitive points, and experiments with different electrode materials. These data are for a counter operated with the point at negative potential.Zeleny's conclusion that a high resistance layer of adsorbed gas exists at the point is adopted. In addition, the assumption is made that the field at the point at the onset of “self-counting” is sufficient to produce auto-electronic emission. This combination now leads to a theory which accounts for the various characteristics of the counter and explains the threshold of counting curve, the auto-counting curve, and the continuous discharge curve. Probability considerations account for the selective counting of different ionizing agents in certain voltage ranges, for the dependence of counting upon path of ionizing rays through the chamber, and for the increase of counts with increase of voltage from threshold of counting to the point where all rays are registered.     

Spectral intensity distribution in a hydrogen discharge

A cold cathode discharge tube has an auxiliary tube attached from which cathode-rays are projected against the main cathode. A photo-electric cell, attached to a monochromatic illuminator, is used to measure relative intensity distribution of H_γ and H_δ respectively, from the main cathode through the cathode dark space into the negative glow with and without excitation of the auxiliary tube. When the main cathode is bombarded by the electron stream the intensity of spectral illumination in the negative glow is increased by about 20 per cent. This increase does not result from the mere addition of an illumination, which appears when the auxiliary tube is alone excited, to the illumination of the main discharge, but may be attributed to the production of soft X-rays in the gas which are capable of exciting the gas molecules.R. Seeliger and co-workers have investigated spectrophotometrically the several characteristic sections of a cold cathode discharge tube. Their method consisted of an examination, with a microphotometer, of spectrograms taken at points along the discharge. The intensity distribution of any spectral line was found continuous in passing from one portion of the discharge to another, e.g., from the Faraday dark space into the positive column, and that the maxima of illumination for different lines appeared displaced relative to one another.A. Wehnelt and A. Jachan demonstrated with several experimental arrangements the effect of bombarding the cold cathode of an ordinary discharge tube with a beam of cathode-rays. There resulted an increase in the total intensity of illumination in the tube together with a shrinkage of the cathode dark space.The purpose of the present investigation was to examine the effect such an electronic bombardment would produce upon the spectral intensity distribution near the cathode of a hydrogen discharge in Hγ and Hδ alone were capable of investigation.     

On the rôle of tube walls,and surface and space charges in electrical discharges through rarefied gases

Several matters pertaining to the part played by tube walls, and surface and space charges in electrical discharges through rarefied gases, are briefly discussed, and experiments are described which throw light on some of the processes involved in such discharges. Measurements made under identical conditions of the falls of potential between striæ in the positive columns of discharges in hydrogen at various pressures in two glass tubes of different diameters showed that for pressures above 1.1 mm. these falls were increasingly greater in the larger tube. The results of experiments done with discharges produced under unusual conditions and bearing on the radial and axial fields present in the positive columns of discharges are described, and photographs of some of the discharges are reproduced in a part of which the positive column was made to pass through a long metal tube placed inside of the glass discharge tube, the two ends of the metal tube being at times both open and at other times both closed with wire gauzes of fine mesh. The potential assumed by the metal tube and the current flowing through its walls were measured, and special experiments were done to elucidate the process by which the current manages to penetrate the more or less field-free space inside the metal cylinder. The distributions of the space and surface charges along the length of a glass discharge tube were measured separately, at least roughly, and the nature of these distributions was found to depend markedly upon whether the anode or the cathode of the discharge tube was connected to earth, although the combined effects of the two charges of necessity produced the same field distribution within the discharge tube in both cases. The gases used in the experiments were air and hydrogen.     

Behavior of positive ions in hydrogen

It has been shown that electrons with 11.5 volts energy can dissociate a hydrogen molecule into its two constituent atoms, but up until recently no experiments have been performed to see whether fast positive ions are able to dissociate hydrogen.In the present experiments Li or Cs positive ions of various velocities are produced in a tube containing hydrogen molecules. The tube is immersed in liquid air, and the rate of decrease of pressure of hydrogen is measured as a function of the velocity of the positive ions. It is found that with no positive ions entering the tube there is a certain decrease in the pressure of the hydrogen due to its thermal dissociation on the hot filament and its subsequent condensation on the cold walls of the tube. With ions of energies from 15 to 320 volts flowing in the tube the rate of decrease of pressure is greater, showing a formation of some condensible product due to the action of the ions.The rate of pressure decrease with the voltage applied has been found to be proportional to the ion current flowing. The rate per unit current is proportional to the pressure; and the rate per unit current per unit pressure is practically independent of the voltage for Li and Cs ions of energies from 15 to 320 volts.The effect has been shown not to be due to secondary electrons.The process may be due to the formation of alkali hydrides in the gas phase. The number of hydrogen molecules disappearing per positive ion entering the tube varies from 0.01 to 0.5. No critical potentials have been found in this experiment, in disagreement with recent experiments of Leipunsky and Schechter.     

Room-temperature coherent manipulation of single-spin qubits in silicon carbide with a high readout contrast

Spin defects in silicon carbide (SiC) with mature wafer-scale fabrication and micro/nano-processing technologies have recently drawn considerable attention. Although room-temperature single-spin manipulation of colour centres in SiC has been demonstrated, the typically detected contrast is less than 2, and the photon count rate is also low. Here, we present the coherent manipulation of single divacancy spins in 4H-SiC with a high readout contrast () and a high photon count rate (150 kilo counts per second) under ambient conditions, which are competitive with the nitrogen-vacancy centres in diamond. Coupling between a single defect spin and a nearby nuclear spin is also observed. We further provide a theoretical explanation for the high readout contrast by analysing the defect levels and decay paths. Since the high readout contrast is of utmost importance in many applications of quantum technologies, this work might open a new territory for SiC-based quantum devices with many advanced properties of the host material.     

套管厚度对探测器探测效率影响的MC研究

本文利用蒙特卡罗MCNP5程序分别模拟研究厚度为3mm探管对测井仪探测效率的影响和探管厚度变化对测井仪探测效率的影响,得出如下主要结论:对3mm探管,随着能量的增加绝对探测效率先增加后慢慢降低。探管厚度越大,1.46MeV的伽马射线被慢化到低能端的相对计数就越多,相应全能峰的相对总计数会慢慢减少,绝对峰探测效率随着探管厚度的增加逐渐降低。     

The magnetic deflection experiments of Curtiss and of Mott-Smith

We have carried out a geometrical analysis which applies to that type of cosmic ray deflection experiment in which an extended region of magnetic field lies between the lower two of three or more Geiger-Mueller counters arranged in line for counting coincident discharges. It is apparent that charged particles of sufficiently low energy will be deviated away from the last counter and that the counting rate will therefore be reduced by application of the field. This paper presents a method for computing what proportion of electrons of a given energy will be eliminated by application of the field. The method is extended to include a constant loss of energy per unit path length as the particle traverses an iron core. The results of the experiments of Curtiss and of Mott-Smith are interpreted in the light of these calculations. Curtiss' result could be explained if all rays were electrons of 4 × 10⁸ volts energy. One may conclude from his observation that if all the radiation consists of positive or negative electrons, the fraction between 2 × 10⁷ volts and 1.5 × 10⁸ volts is less than 30 per cent. of the total above 2 × 10⁷, and that the fraction between 2 × 10⁷ and 10⁹ is greater than 30 per cent. A comparison of Curtiss' and Mott-Smith's experiments yields no reason for doubting the correctness of using the magnetic induction B when computing the deflection within iron. Nor does it necessarily sustain this procedure. An experiment by W. F. G. Swann and the writer is at present under way for the purpose of securing, if possible, more conclusive evidence on this point.     

Residual currents in A.C. discharges.

A point by point determination is made of the residual current flowing during the reignition period of an a.c. arc between pure graphite electrodes in atmospheric air.The air pressure is varied from 0.14 to 5.4 atmospheres absolute and the gap varied from 1/4 to 5 mm. Alternating current of 6o cycles per second is supplied to the arc by a io Kv. power transformer and the r.m.s. discharge current is limited by ohmic resistance to values between o.o5 and 2 amperes. The residual current rises to a peak shortly after the voltage reverses and the current then decreases as the recovery voltage increases to its reignition value. The peak of the residual current increases directly with the r.m.s. current of the arc, and is essentially independent of both the length of the gap and the pressure of the gas. The reignition voltage is shown to be a function of the value of residual current existing just prior to ignition. The rate of decay of residual current decreases as gas pressure and gap length are increased.     

基于选择实验法的胶州湾湿地围垦生态效益损失评估

选择实验法是当前国际上用于评估资源环境价值的前沿方法。本文针对胶州湾湿地围垦生态影响,应用选择实验法,评估湿地围垦造成的生态效益损失,提出生态修复优选方案。在查阅文献和咨询专家的基础上,确定了湿地面积、植被覆盖率、湿地水质和生物多样性4项湿地修复属性。通过对胶州湾地区293名居民进行随机抽样调查,定量评估了湿地修复中不同属性的支付意愿价值,评估结果显示:若将湿地的各项属性修复至基线水平,居民的支付意愿约为321.78元/(年·户),据此测算胶州湾湿地围垦的生态效益损失约为7.67亿元/年。研究结果进一步表明:4个属性中居民对湿地面积变化的关注程度最高,其次是湿地水质,因此政府应当制定以恢复湿地面积为重点的湿地保护和修复政策。     

The velocity of sound

A new method for measuring the velocity of sound over short distances has been devised in which sixty pulses per second cause a sinusoidal curve to appear upon an oscilloscopic screen.As the receiving microphone is moved away from the sound oscillator, the crest of the sine curve moves across the oscilloscope, completing the circle in one-sixtieth of a second. The actual velocity of the sound is easily calculated after the distance moved bv the microphone has been measured.Application of the probability laws and the error curve shows that the method is very accurate, providing the alternating current maintains itself invariably at sixty cycles per second. The average of twelve hundred measurements gives 331.364 ± 0.043 meters per second at zero degrees centrigrade.     

Mica and the Mica industry

The instrument described is an ammeter for measuring currents flowing in the secondary circuits of induction coils.A D'Arsonval system is used, modified by placing a small condenser in parallel with the moving coil and its calibration shunt to compensate for the high rate change of current, and by a ground on one side of the system to prevent sparking between the meter parts.The instrument is especially adapted for use in X-ray work, because it was found that the quantity of X-rays was directly proportional to the current flowing in the tube.     

Variable-structure PD controller for satellite attitude: Stability analysis and design for optimal performance

A novel variable structure controller is investigated for satellite attitude control. This novel controller does not lead to a sliding mode, which avoids the chattering problem, making it suitable for practical implementation. Detailed formulation of the controller is presented along with analytical stability analysis for a second order system. The system having this nonlinear controller is homogeneous, which leads to a similar response at large and small deviations from the equilibrium. A procedure for tuning homogeneous controllers for all initial conditions is proposed. A detailed model of the satellite attitude dynamics, actuator dynamics, and delays in the system is utilized to optimize controller gains numerically. A comparative analysis shows the superiority of the proposed controller over a conventional PID controller in terms of better transients and lower energy consumption.     

Endogenous technical advance and the stochastic trend in output: A neoclassical approach

In the recent endogenous growth literature, the trend in output is stochastic, while investment in scientific knowledge is treated as analogous to a capital stock. This paper models both research and development (R&D) and disembodied technical advance using neo-classical equations, which specify the equilibrium stocks as a function of prices and output. The elasticity of R&D in the production function, estimated using factor shares, is time-varying and increasing. Returns to scale are increasing in all factors. The most important aspect of the model is that the equilibrium rate of technical advance is not cyclically invariant, but co-moves with output at business cycle frequencies. This allows the production function to behave as a stochastic trend. Growth accounting demonstrates that long-term variations in the rate of productivity growth have been associated mainly with low-frequency fluctuations in the rate of disembodied technical advance, with secondary effects from the stocks of R&D and physical capital. During the high productivity period 1948–1972, technical advance contributed 1.48 percentage points per year to output, with 0.98 accounted for by R&D. The productivity slowdown of the mid-1970s was accounted by a gradual decline in the effect of R&D, and a more abrupt collapse in disembodied technology. The subsequent productivity revival was associated with two accelerations in disembodied technical advance, the first beginning in the early 1980s, and the second in the mid-1990s. The production function is simulated in a small econometric model. Model simulations find that exogenous shocks to the inflation rate generate significant variations in growth by inducing fluctuations in disembodied technology.     

公共资源水污染与经济发展关系实证研究——以中小企业数量众多的江苏省为例

工业废水排放是公共资源水污染的主要原因之一。本文选取1995--2007年江苏省经济与工业废水排放数据,分析了经济发展与工业废水排放关系,建立了经济增长与工业废水排放量的水平计量模型,并探究了其演替轨迹。实证研究表明,江苏省经济发展与工业废水排放量呈现一定的环境库兹涅茨曲线特征。针对江苏省中小企业数量众多现状,减少中小企业工业废水排放是减轻公共资源水环境压力和影响经济发展的重要途径。文中最后针对江苏省水污染与经济发展现状给出了减少工业废水排放的几点建议。     

高功率Ni/MH电池用AB5型负极储氢合金的研究

研究和开发具有优异高倍率特性的储氢电极合金是发展高功率型Ni/MH电池的技术关键,具有重大的理论意义和商业价值。基于合金热力学和动力学行为的讨论,研究了AB5型储氢电极合金的微结构对其倍率放电性能的影响。结果表明,由于非化学计量(B/A >5 )和高催化活性第二相的引入,B侧添加硼或钼可以显著提高合金的高倍率放电容量和低温放电容量。进一步结合A侧稀土成分优化,发展出一类具有优异倍率性能的MmNi3.55Co0.75Mn0.4Al0.3Bx(Mm为混合稀土)合金。该系列合金有望应用于高功率Ni/MH电池和低温( - 35 oC)Ni/MH电池。     

PublicationHarvester: An open-source software tool for science policy research

We present PublicationHarvester, an open-source software tool for gathering publication information on individual life scientists. The software interfaces with MEDLINE, and allows the end-user to specify up to four MEDLINE-formatted names for each researcher. Using these names along with a user-specified search query, PublicationHarvester generates yearly publication counts, optionally weighted by Journal Impact Factors. These counts are further broken-down by order on the authorship list (first, last, second, next-to-last, middle) and by publication type (clinical trials, regular journal articles, reviews, letters/editorials, etc.) The software also generates a keywords report at the scientist-year level, using the medical subject headings (MeSH) assigned by the National Library of Medicine to each publication indexed by MEDLINE. The software, source code, and user manual can be downloaded at http://www.stellman-greene.com/PublicationHarvester/.     

Incorrect order of draw could be mitigate the patient safety: a phlebotomy management case report

Procedures involving phlebotomy are critical for obtaining diagnostic blood specimens and represent a well known and recognized problem, probably among the most important issues in laboratory medicine. The aim of this report is to show spurious hyperkalemia and hypocalcemia due to inadequate phlebotomy procedure. The diagnostic blood specimens were collected from a male outpatient 45 years old, with no clinical complaints. The tubes drawing order were as follows: i) clot activator and gel separator (serum vacuum tube), ii) K₃EDTA, iii) a needleless blood gas dedicated-syringe with 80 I.U. lithium heparin, directly connected to the vacuum tube holder system. The laboratory testing results from serum vacuum tube and dedicated syringe were 4.8 and 8.5 mmol/L for potassium, 2.36 and 1.48 mmol/L for total calcium, respectively. Moreover 0.15 mmol/L of free calcium was observed in dedicated syringe. A new blood collection was performed without K₃EDTA tube. Different results were found for potassium (4.7 and 4.5 mmol/L) and total calcium (2.37 and 2.38 mmol/L) from serum vacuum tube and dedicated syringe, respectively. Also free calcium showed different concentration (1.21 mmol/L) in this new sample when compared with the first blood specimen. Based on this case we do not encourage the laboratory managers training the phlebotomists to insert the dedicated syringes in needle-holder system at the end of all vacuum tubes. To avoid double vein puncture the dedicated syringe for free calcium determination should be inserted immediately after serum tubes before EDTA vacuum tubes.     

A procedure to obtain the initial amplitude and phase for the Krylov–Bogoliubov method

Using the Krylov–Bogoliubov method for obtaining analytical solutions to systems with small non-linearities, a procedure is employed to determine the initial amplitude and phase in terms of the initial displacement and velocity. Equations representing the time rate of change of amplitude and phase are used directly. Whether the corresponding linear equations of the non-linear system has purely imaginary, complex conjugate or real roots, the same procedure can be applied.An example is given which demonstrates the initial amplitude and phase change for various higher order approximations.     

关于技术资产评估中折现率构成及变化的研究

科学地评估技术资产的价值,对于确保技术资产交易的公平性、促进我国高新技术发展具有十分重要的意义。在运用收益法对技术资产进行评估时,折现率取值的很小差异会对评估结果产生很大影响,而如何确定技术资产的折现率则属于我国资产评估的前沿问题。在此,对技术资产折现率的研究包括：1)折现率实质、影响因素与选取缺陷;2)折现率的基本构成及其变化;3)折现率及其变化值的确定。     

基于CTGAL电路的进制可变计数器设计

通过对计数器和钟控传输门绝热逻辑(clocked transmission gate adiabatic logic,CTGAL)电路工作原理及结构的研究,提出了基于CTGAL电路的四/八/十六进制可变计数器设计方案,与传统CMOS电路实现的四/八/十六进制计数器相比,在相同工作频率下,平均节省能耗约87%。HSPICE模拟结果表明了所设计的电路具有正确的逻辑功能和显著的低功耗特性。