应用于三维光学测量系统之照明光源设计

目前,发光二极管(Light Emitting Diode,LED)作为一种数字显示元件,已经获得广泛的应用,但是在其他领域,诸如照明等还处于起步和探索阶段.本文介绍了基于大功率LED的光照补偿光源的原理、设计过程等.在分析论证的基础上,依据斯派罗准则,通过计算,并且依照实际需要对所得结果进行修正,得到了适合需要的设计.最后,根据实际的需要以及相应的评判标准-五点均匀法则,指出了所设计光源的优越性,同时,根据前后的仿真结果,分析了前后差异的原因.     

On electron optics

For many experiments in physics and in some engineering applications, it is necessary to produce electron bundles, or as they are often called, “electron beams” of considerable intensities.Various methods have been used for directing a cloud of electrons evaporated from an emitting surface into a beam and then concentrating this beam to a desired degree. The concentration of electron beam in high vacuum depends entirely upon fields of force, either electric or magnetic, while in low vacuum or in rarified rare gas it depends also upon the action of the field of ionized gas molecules.In high vacuum the fields of force act upon the electron beam in a manner similar to the action of lenses upon a beam of light. An improperly shaped field produces effects similar to spherical aberration in poorly corrected lenses; non-uniform velocity of electrons in the beam results in effects similar to chromatic aberration of light.This optical analogy is not perfect.In the case of the electron beam the velocity varies continuously throughout most of the path and indices of refraction employed usually are greater than in the optical case. Moreover, space charge in beams of high intensity limits the concentration attainable; consequently, even theoretically, an electron beam can never be brought up to a mathematical point as in the case of light optics. Many secondary effects are present which complicate the problem still further.In focusing electron beams, both electrostatic and electromagnetic methods have been used extensively. The electrostatic method, however, seems to be preferable, especially when the beam is to be deflected. Precautions should be taken not to destroy the focusing of the beam during deflection.     

A note on the time required to set up conduction in an FG-17 thyratron as determined by a study of a linear time axis circuit for an oscillograph

In connection with a study of small thyratrons recently published, certain results seemed to indicate that 1,000 micro-seconds were required to set up conduction, but an investigation using a cathode-ray oscillograph definitely shows that good conduction can be set up in 10 to 20 micro-seconds. A satisfactory explanation of the earlier result, not requiring a time lag, has been suggested by O. W. Livingston of the General Electric Company.     

Inter‐firm Migration of Tacit Knowledge: Law and Policy1

Abstract

Much knowledge is diffused by the exchange of property rights in intangibles. But tacit knowledge, not being subject to property rights, is instead diffused by migration of knowledgeable individuals between firms. The law impacts significantly on this diffusion mechanism, in particular those rules that determine the use individuals may make of their tacit knowledge after migration to a different firm. The general principle underlying the relevant law is that individuals are free to migrate with all their tacit knowledge. Nonetheless there are some narrow exceptions to this principle. That these exceptions remain narrow and carefully policed by the courts is important because imposing too many restraints on use of tacit knowledge post‐term would have a negative impact on real innovation.     

劈尖干涉理论及应用

介绍了劈尖干涉的原理,利用分振幅法将一束光分为两束光,在介质膜上、下表面反射的光在膜的上表面附近相遇,而发生干涉,在介质表面就会观察到明暗相间、等间距的条纹。探讨了劈尖干涉理论在检查平面的平整度及计算平面凹凸的深度、测量微小长度、微小角度等很多实际应用的结论,改进了测量微笑长度的方法。     

带状电子注空间电荷波色散特性研究

在引导磁场无限大的情况下,对平板波导中带状电子注进行理论分析,得出了行列式形式的色散方程并进行数值计算。研究了空间电荷波色散曲线随电子密度、电子注厚度和电子注能量等参量的变化规律,这些规律对带状注器件的研究具有一定的参考价值。     

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.     

Leaderless consensus control of nonlinear multi-agent systems under directed topologies subject to input saturation using adaptive event-triggered mechanism

This paper deals with the leaderless consensus controller design for nonlinear multi-agent systems (MASs) subject to the input saturation nonlinearity by using an event-triggered (ET) mechanism. An adaptive ET scheme has been established with variable threshold parameter for attaining an efficient control bandwidth. Linear parameter varying (LPV) formulation and region of stability investigation for dealing with the inherent nonlinearity and input saturation, respectively, are focused in the study. A consensus controller design condition has been formulated to ensure the regional stability, to determine the consensus protocol gains, to choose the parameters of ET mechanism, and to select an appropriate adaptation law for ET control. Elimination of Zeno behavior, based on nonlinearity bounds, for the adaptive ET mechanism has been ensured through a rigorous analysis. In contrast to excising methods, a directed communication topology, adaptive ET mechanism, and removal of Zeno behavior as well as elimination of the windup effect of saturation have been considered in our work. A simulation study has been provided for six robotic agents and comparison results with the existing method are revealed.     

Optoelectrofluidic field separation based on light-intensity gradients

Optoelectrofluidic field separation (OEFS) of particles under light -intensity gradient (LIG) is reported, where the LIG illumination on the photoconductive layer converts the short-ranged dielectrophoresis (DEP) force to the long-ranged one. The long-ranged DEP force can compete with the hydrodynamic force by alternating current electro-osmosis (ACEO) over the entire illumination area for realizing effective field separation of particles. In the OEFS system, the codirectional illumination and observation induce the levitation effect, compensating the attenuation of the DEP force under LIG illumination by slightly floating particles from the surface. Results of the field separation and concentration of diverse particle pairs (0.82–16 μm) are well demonstrated, and conditions determining the critical radius and effective particle manipulation are discussed. The OEFS with codirectional LIG strategy could be a promising particle manipulation method in many applications where a rapid manipulation of biological cells and particles over the entire working area are of interest.     

Does lead userness foster idea implementation and diffusion? A study of internal shopfloor users

While the relevance of lead users has been well established for the early phases of the innovation process, such as ideation and creativity, the relationship between lead userness and implementation and diffusion has not been investigated. This is surprising, as the conjecture that lead user ideas are more likely to be implemented and diffused than non-lead user ideas is a key tenet of lead user research. To test this conjecture we draw on a sample of 87 internal process users in a large electronics firm who submitted ideas to an idea management system. 452 ideas were suggested, of which 148 were implemented and 33 further diffused on the shopfloor. We find that higher lead userness is positively and significantly associated with the likelihood of suggested ideas being implemented and diffused. This effect is substantial: Ideas coming from lead users were more than two times more likely to be implemented and more than three times more likely to be diffused than ideas coming from non-lead users. We conclude that lead user ideas are more likely than non-lead user ideas to be implemented and diffused throughout a social system, which arguably constitutes the ultimate success of any idea. Our research contributes to research on (internal) lead users, idea management systems, and idea implementation and diffusion.     

基于ArcGIS的地貌晕渲法可视化表达与分析

晕渲法是利用色彩和光影有规律的变换和组合来表示地表起伏变化的方法。基于ArcGIS平台,文章首先分析了光源方向（光照角）、光源入射角（高度角）和垂直比例因子的选择对黑白晕渲效果的影响,然后分析了基于黑白晕渲和分层设色的彩色晕渲图制作方法,对实践工作具有较强指导意义。     

从技术创新到社会技术系统转型——工业革命先导产业创新驱动发展的历史启示

突破性技术创新是如何产生的,它又如何逐步推动产业升级。人类工业革命的先导、18世纪英国纺纱技术的创新发展和扩散过程依然是一个值得关注的标本式案例,对这一案例的深入研究可以揭示从技术创新到技术与社会的协同演化并最终促成社会技术系统转型的基本路径,也可获得当前我国创新驱动发展的启示。     

An integrated platform enabling optogenetic illumination of Caenorhabditis elegans neurons and muscular force measurement in microstructured environments

Optogenetics has been recently applied to manipulate the neural circuits of Caenorhabditis elegans (C. elegans) to investigate its mechanosensation and locomotive behavior, which is a fundamental topic in model biology. In most neuron-related research, free C. elegans moves on an open area such as agar surface. However, this simple environment is different from the soil, in which C. elegans naturally dwells. To bridge up the gap, this paper presents integration of optogenetic illumination of C. elegans neural circuits and muscular force measurement in a structured microfluidic chip mimicking the C. elegans soil habitat. The microfluidic chip is essentially a ∼1 × 1 cm² elastomeric polydimethylsiloxane micro-pillar array, configured in either form of lattice (LC) or honeycomb (HC) to mimic the environment in which the worm dwells. The integrated system has four key modules for illumination pattern generation, pattern projection, automatic tracking of the worm, and force measurement. Specifically, two optical pathways co-exist in an inverted microscope, including built-in bright-field illumination for worm tracking and pattern generation, and added-in optogenetic illumination for pattern projection onto the worm body segment. The behavior of a freely moving worm in the chip under optogenetic manipulation can be recorded for off-line force measurements. Using wild-type N2 C. elegans, we demonstrated optical illumination of C. elegans neurons by projecting light onto its head/tail segment at 14 Hz refresh frequency. We also measured the force and observed three representative locomotion patterns of forward movement, reversal, and omega turn for LC and HC configurations. Being capable of stimulating or inhibiting worm neurons and simultaneously measuring the thrust force, this enabling platform would offer new insights into the correlation between neurons and locomotive behaviors of the nematode under a complex environment.     

An integrated actuating and sensing system for light-addressable potentiometric sensor (LAPS) and light-actuated AC electroosmosis (LACE) operation

To develop a lab on a chip (LOC) integrated with both sensor and actuator functions, a novel two-in-one system based on optical-driven manipulation and sensing in a microfluidics setup based on a hydrogenated amorphous silicon (a-Si:H) layer on an indium tin oxide/glass is first realized. A high-intensity discharge xenon lamp functioned as the light source, a chopper functioned as the modulated illumination for a certain frequency, and a self-designed optical path projected on the digital micromirror device controlled by the digital light processing module was established as the illumination input signal with the ability of dynamic movement of projected patterns. For light-addressable potentiometric sensor (LAPS) operation, alternating current (AC)-modulated illumination with a frequency of 800 Hz can be generated by the rotation speed of the chopper for photocurrent vs bias voltage characterization. The pH sensitivity, drift coefficient, and hysteresis width of the Si₃N₄ LAPS are 52.8 mV/pH, −3.2 mV/h, and 10.5 mV, respectively, which are comparable to the results from the conventional setup. With an identical two-in-one system, direct current illumination without chopper rotation and an AC bias voltage can be provided to an a-Si:H chip with a manipulation speed of 20 μm/s for magnetic beads with a diameter of 1 μm. The collection of magnetic beads by this light-actuated AC electroosmosis (LACE) operation at a frequency of 10 kHz can be easily realized. A fully customized design of an illumination path with less decay can be suggested to obtain a high efficiency of manipulation and a high signal-to-noise ratio of sensing. With this proposed setup, a potential LOC system based on LACE and LAPS is verified with the integration of a sensor and an actuator in a microfluidics setup for future point-of-care testing applications.     

高能气动喷丸致纯铜细晶化的实验与模拟

高能气动喷丸是通过剧烈塑性变形产生细晶材料的方法之一．用纯铜作为实验材料在高能气动喷丸实验机上作喷丸实验,利用表面形貌仪、显微硬度仪以及电子背散射衍射方法对经喷丸处理的试样进行表面粗糙度、硬度及晶粒尺度的测量．结果表明,表面粗糙度随处理时间的增长呈指数衰减趋势;晶粒尺度细化了一个量级,由初始的２５.４８μｍ细化至２５２μｍ;且显微硬度由原来的０５８ＧＰａ增加到１２５ＧＰａ．量纲分析得到喷丸过程的５个无量纲参数,利用有限元模拟研究了无量纲参数的影响．自编制程序产生丸粒的随机碰撞并调用Ａｎｓｙｓ?ｌｓ ｄｙｎａ模拟碰撞过程,并将模拟１０００次碰撞的结果与相应的实验值进行了比较．     

Serum Lipid Profile: Fasting or Non-fasting?

Serum lipid profile has now become almost a routine test. It is usually done in fasting state due to certain limitations in non-fasting serum sample. In the recent past efforts have been made to simplify blood sampling by replacing fasting lipid profile with non-fasting lipid profile. However, fasting specimen is preferred if cardiovascular risk assessment is based on total cholesterol, LDL cholesterol or non-HDL cholesterol. A lot has yet to be done in this area. Till then we have to believe in fasting lipid profile for assessment and management of cardiovascular disease.     

Development and validation of a Disaster Management Metamodel (DMM)

Disaster Management (DM) is a diffused area of knowledge. It has many complex features interconnecting the physical and the social views of the world. Many international and national bodies create knowledge models to allow knowledge sharing and effective DM activities. But these are often narrow in focus and deal with specified disaster types. We analyze thirty such models to uncover that many DM activities are actually common even when the events vary. We then create a unified view of DM in the form of a metamodel. We apply a metamodelling process to ensure that this metamodel is complete and consistent. We validate it and present a representational layer to unify and share knowledge as well as combine and match different DM activities according to different disaster situations.     

Characterizing multi-domain false news and underlying user effects on Chinese Weibo

False news that spreads on social media has proliferated over the past years and has led to multi-aspect threats in the real world. While there are studies of false news on specific domains (like politics or health care), little work is found comparing false news across domains. In this article, we investigate false news across nine domains on Weibo, the largest Twitter-like social media platform in China, from 2009 to 2019. The newly collected data comprise 44,728 posts in the nine domains, published by 40,215 users, and reposted over 3.4 million times. Based on the distributions and spreads of the multi-domain dataset, we observe that false news in domains that are close to daily life like health and medicine generated more posts but diffused less effectively than those in other domains like politics, and that political false news had the most effective capacity for diffusion. The widely diffused false news posts on Weibo were associated strongly with certain types of users — by gender, age, etc. Further, these posts provoked strong emotions in the reposts and diffused further with the active engagement of false-news starters. Our findings have the potential to help design false news detection systems in suspicious news discovery, veracity prediction, and display and explanation. The comparison of the findings on Weibo with those of existing work demonstrates nuanced patterns, suggesting the need for more research on data from diverse platforms, countries, or languages to tackle the global issue of false news. The code and new anonymized dataset are available at https://github.com/ICTMCG/Characterizing-Weibo-Multi-Domain-False-News.     

A method for the precise measurement of optical path-difference,especially in stressed glass

In connection with an investigation that involved the measurement of optical path-difference and thence birefringence it became necessary to have much higher accuracy than is ordinarily attained. After a careful study of the various methods available it appeared that the one which best meets the requirements of precision and simplicity is a method first elaborated by Friedel (1893), and based on an interesting property possessed by a fixed combination of (1) a polarizer, (2) the birefracting material, and (3) a quarter-wave plate, each placed in a definite orientation to the others. When plane parallel monochromatic light passes through the elements of this fixed combination in the order shown above, the emergent light is plane polarized and the azimuth is related in a simple manner to the path-difference of the specimen. Since this azimuth can be measured by means of an analyzer and graduated circle, the determination of path-difference thus reduces itself to the measurement of an angular displacement, which can be done easily and with high precision.The method was first made applicable to a petrographic microscope for the purpose of determining the path-difference at a given spot in small specimens. Later, there was constructed a separate polarimeter in which large specimens could be conveniently measured. This instrument has given all that was expected of it in facility and rapidity of taking readings, and for any path-difference has a sensitivity about one hundred times greater than that of the devices in common use.A resumé of the general relations for elliptically polarized light as applied to the present method is given, and the magnitude of the errors that may arise is discussed in detail.     

约翰·雷《英语谚语集》展示的生活世界

在西方社会中,人们很早就认识到谚语的功能和意义,并有意识地收集谚语。然而随着近代理性主义的兴起,谚语传统一度受到忽视,不仅＂谚语＂（proverb）一词的语义缩减,谚语的语境范围也从广阔的生活世界退守至狭隘的文学与民俗学研究。近年来谚语研究出现新的进展,谚语中包含的博物学思想也逐渐受到重视。本文拟从英国博物学家约翰·雷编写的《英语谚语集》入手,在博物学语境下探讨谚语中展现的生活世界,剖析谚语与博物学的关系。