五自由度运动误差测量系统关键技术研究

设计了一种基于激光准直原理的运动平台激光五自由度运动误差测量系统,该系统基于双平行光束的准直原理对水平直线度、垂直直线度、偏摆角、俯仰角和滚转角误差进行同步测量.进行了系统直线度、偏摆角和俯仰角误差测量核心器件参数的自标定,针对双光束难以调平影响滚转角误差测量准确度的问题,利用水平仪对滚转角误差进行补偿修正.对整套系统...     

一种新型大尺寸长度校准装置的研制

介绍了一种新型的大尺寸长度校准装置,该装置解决了激光干涉仪等高精度大尺寸长度测量仪器的实验室校准与溯源问题.通过采用三路相干光进行测长,根据两辅助光路与主光路的测长偏差计算阿贝角,实现了阿贝误差的实时补偿.利用标准双频激光干涉仪测试了阿贝误差的补偿精度,35 m测量范围内的比对误差小于±3μm.测量精度达到了单光路同轴测量的水平.     

高精度80m大长度激光比长装置的研制

介绍了中国计量科学研究院研制的80m大长度激光比长装置,该装置由81m导轨、无阿贝误差测长系统、折射率实时修正系统等多个部分构成,填补了我国大长度标准的空白。装置测量不确定度为U=0.07μm+0.07×10~(-6)L(k=2),关键指标处于国际先进水平。     

直线导轨滚转角测量误差自校正方法

提出一种具有滚转角测量自动校正功能的五自由度运动误差测量系统,解决了平行双光束法在测量滚转角误差时受光束平行度影响较大的问题。介绍了平行双光束法测量五自由度运动误差的原理,建立了关于双光束平行度误差与滚转角测量误差间的模型,提出了基于双自准直单元的双光束平行度误差测量方法。实验结果表明:双光束之间存在15.4″的平行度误差时,可以将滚转角测量误差的残差由44″减小到2.7″。该校正方法有效提高了双光束测量滚转角的准确性,可用于直线导轨运动误差的在线监测。     

齿轮啮合分离测试技术中的测量齿轮误差修正

本文介绍齿轮啮合分离测试技术的测量齿轮误差修正技术，它运用最小区域法计算测量齿轮的压力角和螺旋角误差对其进行修正，利用切比雪夫多项多拟合测量齿轮的形状误差进行修正，试验结果表明修正技术可大大降低了测量齿轮精度要求，能使工作的配对件作为测量齿轮。     

基于地磁信息的火箭弹滚转角测量系统研究

在火箭弹飞行过程中,为实现火箭弹弹道修正,需实时解算弹体的滚转角。该文根据地磁场基本特性和火箭弹飞行过程中姿态变化关系,通过姿态变换矩阵,建立滚转角解算数学模型。搭建基于地磁信息的滚转角测量系统,采用两轴磁传感器测量地磁场矢量,辨识火箭弹滚转姿态信息。滚转角系统在火箭弹上进行飞行搭载试验,结果表明,利用地磁得到的解算滚转角线性度良好,与陀螺测得的弹体旋转速度相匹配,能够满足火箭弹弹道修正的要求。     

基于地磁测量的火箭弹滚转角解算误差补偿方法研究

为实现火箭弹弹道修正,需实时解算弹体的滚转角。根据地磁场基本特性,采用两轴磁传感器测量地磁场分量,并同时测量弹道倾角以解算弹体姿态角。提出一种火箭弹弹体滚转角解算的误差补偿方法,进行某型火箭弹打靶试验,利用该方法对火箭弹飞行试验过程中的姿态角数据进行实时解算,并与陀螺测量到的滚转角数据进行比较。试验结果表明:利用该方法解算滚转角准确度在4°以内,能够满足火箭弹弹道修正的要求。     

红外测量系统动态测角误差分析

介绍了一种光电测量设备红外测量系统动态测角误差检测方法，该方法是通过将红外系统测量数据与主摄影系统测量数据相比对，并对红外系统与主摄影系统平行度进行了定点修正，且与主摄影系统动态测角误差合成后实现的，叙述了检测设备的组成、检测方法、数据处理过程及测量结果，这一检测方法适用于具有摄影系统的光电测量设备的红外系统和电视系统等其它分系统动态测角误差的检测。     

双旋弹丸滚转测量系统设计与实现

为实现固定翼双旋弹弹道修正,需对弹体和鸭舵滚转信息进行测量。该文针对双旋弹丸鸭舵反旋和弹体高速旋转的特点,建立弹体和鸭舵滚转姿态解算模型,设计基于地磁和霍尔传感器的滚转测量系统。采用波形变换方法将正弦波形式地磁信号转换为易于测量的方波信号,并使用高通滤波器和迟滞比较器对含噪地磁信号进行优化,通过定时器捕获分别得到弹体和鸭舵转速信息,在此基础上通过线性插值得到滚转角信息。地面半实物仿真平台实验表明该滚转测量系统弹体转速测量跳动为–0.3~0.2 Hz,鸭舵相对弹体转速测量跳动为–0.15~0.15 Hz,滚转角测量跳动为–2°~1°,能够满足双旋弹弹道修正的要求。     

关于电子经纬仪i角误差修正的探讨

本文简要介绍了电子经纬仪i角误差修正的原理,并介绍了如何检测i角误差,并结合作者多年的检测经验对电子经纬仪i角误差修正的方法进行深入地探讨.     

Optimal decision-making in mammals: insights from a robot study of rodent texture discrimination

Texture perception is studied here in a physical model of the rat whisker system consisting of a robot equipped with a biomimetic vibrissal sensor. Investigations of whisker motion in rodents have led to several explanations for texture discrimination, such as resonance or stick-slips. Meanwhile, electrophysiological studies of decision-making in monkeys have suggested a neural mechanism of evidence accumulation to threshold for competing percepts, described by a probabilistic model of Bayesian sequential analysis. For our robot whisker data, we find that variable reaction-time decision-making with sequential analysis performs better than the fixed response-time maximum-likelihood estimation. These probabilistic classifiers also use whatever available features of the whisker signals aid the discrimination, giving improved performance over a single-feature strategy, such as matching the peak power spectra of whisker vibrations. These results cast new light on how the various proposals for texture discrimination in rodents depend on the whisker contact mechanics and suggest the possibility of a common account of decision-making across mammalian species.     

Sliding-induced non-uniform pre-tension governs robust and reversible adhesion: a revisit of adhesion mechanisms of geckos

Several mechanisms have been proposed in the literature to explain the robust attachment and rapid, controllable detachment of geckos'' feet on vertical walls or ceilings, yet, it is still debatable, which one is ultimately responsible for geckos'' extraordinary capabilities for robust and reversible adhesion. In this paper, we re-examine some of the key movements of geckos'' spatula pads and seta hairs during attachment and detachment, and propose a sequence of simple mechanical steps that would lead to the extraordinary properties of geckos observed in experiments. The central subject under study here is a linear distribution of pre-tension along the spatula pad induced by its sliding motion with respect to a surface. The resulting pre-tension, together with a control of setae''s pulling force and angle, not only allows for robust and strong attachment, but also enables rapid and controllable detachment. We perform computational modelling and simulations to validate the following key steps of geckos'' adhesion: (i) creation of a linear distribution of pre-tension in spatula through sliding, (ii) operation of an instability envelope controlled by setae''s pulling force and angle, (iii) triggering of an adhesion instability leading to partial decohesion along the interface, and (iv) complete detachment of spatula through post-instability peeling. The present work not only reveals novel insights into the adhesion mechanism of geckos, but also develops a powerful numerical simulation approach as well as additional guidelines for bioinspired materials and devices.     

记忆中介下交互叙事设计对民俗传播的影响

目的 从交互叙事设计的研究视角拓展了民俗文化传播的方法与路径。方法 梳理叙事与记忆、记忆与民俗文化、交互叙事设计与民俗文化传播之间的关系内涵,挖掘交互叙事设计与民俗文化传播之间的深层关联,通过搜集相关数据、运用核心理论建立数据模型,探索和研究交互叙事设计对民俗文化传播的影响。结果 验证了交互叙事设计对民俗文化传播、记忆中介的正向影响;隐性记忆对文化认知、文化认同的正向影响;显性记忆对文化认知的正向影响。证实了记忆在民俗交互叙事设计和文化传播之间所起的重要连接作用。明确了可通过交互叙事设计提升用户对民俗文化的认知与认同,为今后相关学者的深入研究提供了一定的参考。结论 交互叙事设计可以拓宽民俗文化传播研究的视野,在引导优秀传统文化的创新性发展,增强民众的文化自信、自强、自觉意识等方面具有重要的意义。     

Constructing and characterizing a bioactive small molecule and microRNA association network for Alzheimer's disease

Alzheimer''s disease (AD) is an incurable neurodegenerative disorder. Much effort has been devoted to developing effective therapeutic agents. Recently, targeting microRNAs (miRNAs) with small molecules has become a novel therapy for human diseases. In this study, we present a systematic computational approach to construct a bioactive Small molecule and miRNA association Network in AD (SmiRN-AD), which is based on the gene expression signatures of bioactive small molecule perturbation and AD-related miRNA regulation. We also performed topological and functional analysis of the SmiRN-AD from multiple perspectives. At the significance level of p ≤ 0.01, 496 small molecule–miRNA associations, including 25 AD-related miRNAs and 275 small molecules, were recognized and used to construct the SmiRN-AD. The drugs that were connected with the same miRNA tended to share common drug targets (p = 1.72 × 10⁻⁴) and belong to the same therapeutic category (p = 4.22 × 10⁻⁸). The miRNAs that were linked to the same small molecule regulated more common miRNA targets (p = 6.07 × 10⁻³). Further analysis of the positive connections (quinostatin and miR-148b, amantadine and miR-15a) and the negative connections (melatonin and miR-30e-5p) indicated that our large-scale predictions afforded specific biological insights into AD pathogenesis and therapy. This study proposes a holistic strategy for deciphering the associations between small molecules and miRNAs in AD, which may be helpful for developing a novel effective miRNA-associated therapeutic strategy for AD. A comprehensive database for the SmiRN-AD and the differential expression patterns of the miRNA targets in AD is freely available at http://bioinfo.hrbmu.edu.cn/SmiRN-AD/.     

An analytical approach to bistable biological circuit discrimination using real algebraic geometry

Biomolecular circuits with two distinct and stable steady states have been identified as essential components in a wide range of biological networks, with a variety of mechanisms and topologies giving rise to their important bistable property. Understanding the differences between circuit implementations is an important question, particularly for the synthetic biologist faced with determining which bistable circuit design out of many is best for their specific application. In this work we explore the applicability of Sturm''s theorem—a tool from nineteenth-century real algebraic geometry—to comparing ‘functionally equivalent’ bistable circuits without the need for numerical simulation. We first consider two genetic toggle variants and two different positive feedback circuits, and show how specific topological properties present in each type of circuit can serve to increase the size of the regions of parameter space in which they function as switches. We then demonstrate that a single competitive monomeric activator added to a purely monomeric (and otherwise monostable) mutual repressor circuit is sufficient for bistability. Finally, we compare our approach with the Routh–Hurwitz method and derive consistent, yet more powerful, parametric conditions. The predictive power and ease of use of Sturm''s theorem demonstrated in this work suggest that algebraic geometric techniques may be underused in biomolecular circuit analysis.     

Selection methods regulate evolution of cooperation in digital evolution

A key, yet often neglected, component of digital evolution and evolutionary models is the ‘selection method’ which assigns fitness (number of offspring) to individuals based on their performance scores (efficiency in performing tasks). Here, we study with formal analysis and numerical experiments the evolution of cooperation under the five most common selection methods (proportionate, rank, truncation-proportionate, truncation-uniform and tournament). We consider related individuals engaging in a Prisoner''s Dilemma game where individuals can either cooperate or defect. A cooperator pays a cost, whereas its partner receives a benefit, which affect their performance scores. These performance scores are translated into fitness by one of the five selection methods. We show that cooperation is positively associated with the relatedness between individuals under all selection methods. By contrast, the change in the performance benefit of cooperation affects the populations’ average level of cooperation only under the proportionate methods. We also demonstrate that the truncation and tournament methods may introduce negative frequency-dependence and lead to the evolution of polymorphic populations. Using the example of the evolution of cooperation, we show that the choice of selection method, though it is often marginalized, can considerably affect the evolutionary dynamics.     

Estimating Young's modulus of zona pellucida by micropipette aspiration in combination with theoretical models of ovum

The zona pellucida (ZP) is the spherical layer that surrounds the mammalian oocyte. The physical hardness of this layer plays a crucial role in fertilization and is largely unknown because of the lack of appropriate measuring and modelling methods. The aim of this study is to measure the biomechanical properties of the ZP of human/mouse ovum and to test the hypothesis that Young''s modulus of the ZP varies with fertilization. Young''s moduli of ZP are determined before and after fertilization by using the micropipette aspiration technique, coupled with theoretical models of the oocyte as an elastic incompressible half-space (half-space model), an elastic compressible bilayer (layered model) or an elastic compressible shell (shell model). Comparison of the models shows that incorporation of the layered geometry of the ovum and the compressibility of the ZP in the layered and shell models may provide a means of more accurately characterizing ZP elasticity. Evaluation of results shows that although the results of the models are different, all confirm that the hardening of ZP will increase following fertilization. As can be seen, different choices of models and experimental parameters can affect the interpretation of experimental data and lead to differing mechanical properties.     

Crowdsourcing contest dilemma

Crowdsourcing offers unprecedented potential for solving tasks efficiently by tapping into the skills of large groups of people. A salient feature of crowdsourcing—its openness of entry—makes it vulnerable to malicious behaviour. Such behaviour took place in a number of recent popular crowdsourcing competitions. We provide game-theoretic analysis of a fundamental trade-off between the potential for increased productivity and the possibility of being set back by malicious behaviour. Our results show that in crowdsourcing competitions malicious behaviour is the norm, not the anomaly—a result contrary to the conventional wisdom in the area. Counterintuitively, making the attacks more costly does not deter them but leads to a less desirable outcome. These findings have cautionary implications for the design of crowdsourcing competitions.     

Preventing Alzheimer's disease by means of natural selection

The amyloid cascade model for the origin of sporadic forms of Alzheimer''s disease (AD) posits that the imbalance in the production and clearance of beta-amyloid is a necessary condition for the disease. A competing theory called the entropic selection hypothesis asserts that the primary cause of sporadic AD is age-induced mitochondrial dysregulation and the following cascade of events: (i) metabolic reprogramming—the upregulation of oxidative phosphorylation in compensation for insufficient energy production in neurons, (ii) natural selection—competition between intact and reprogrammed neurons for energy substrates and (iii) propagation—the spread of the disease due to the selective advantage of neurons with upregulated metabolism. Experimental studies to evaluate the predictions of the amyloid cascade model are being continually retuned to accommodate conflicts of the predictions with empirical data. Clinical trials of treatments for AD based on anti-amyloid therapy have been unsuccessful. We contend that these anomalies and failures stem from a fundamental deficit of the amyloid hypothesis: the model derives from a nuclear-genomic perspective of sporadic AD and discounts the bioenergetic processes that characterize the progression of most age-related disorders. In this article, we review the anomalies of the amyloid model and the theoretical and empirical support for the entropic selection theory. We also discuss the new therapeutic strategies based on natural selection which the model proposes.     

论校准实验室质量体系建设

校准实验室质量体系建设是校准实验室管理的重要课题。本文结合工作实践和经验讨论了校准实验室认可、质量管理、用户满意、与员工沟通等相关问题。