Kinematics Analysis and Singularity Avoidance of a Parallel Mechanism with Kinematic Redundancy

The kinematic redundancy is considered as a way to improve the performance of the parallel mechanism.In this paper,the kinematics performance of a three degree-of-freedom parallel mechanism with kinematic redundancy(3-DOF PM-KR)and the influence of redundant parts on the PM-KR are analyzed.Firstly,the kinematics model of the PM-KR is established.The inverse solutions,the Jacobian matrix,and the workspace of the PM-KR are solved.Secondly,the influence of redundancy on the PM-KR is analyzed.Since there exists kinematic redundancy,the PM-KR possesses fault-tolerant performance.By locking one actuating joint or two actuating joints simultaneously,the fault-tolerant workspace is obtained.When the position of the redundant part is changed,the workspace and singularity will be changed.The results show that kinematic redundancy can be used to avoid singularity.Finally,the simulations are performed to prove the theoretical analysis.

Reliability Analysis of a Mixed Redundant Model in C 3I System

Aim To define a mixed redundant model(MRM), improving the reliability of C 3I system. Methods The model combined the technology characters of two? unit system with one warm stand by unit and function substitute system. The reliability and availability equations of MRM were deduced. Results and Conclusion Compared with several other reliability models, it has obvious effect upon improving the system reliability. The effect? cost rate is very high among these models. The model can be used in reliability design, evaluation and check of C 3I system. Only a little attached cost is needed to improve C 3I system reliability effectively.

Performance Degradation and Reliability Analysis for Redundant Actuation System

Redundant actuator is the key component of Fly-By-Wire （FBW） system in which exists the inherent force fighting among different redundant channels at colligation point, This paper establishes the mathematical model of quad redundant actuator （QRA）, investigates the force equalization algorithm and carries out the performance degradation simulation and reliability analysis under the first failure and the second failure. The results indicate that the optimal equalization algorithm can solve the force fighting effectively, and the QRA can operate at degradation performance continuously under the first failure and the second failure. With the dynamic fault tree analysis, this paper calculates the reliability based on the performance of QRA and proves that the redundant actuator has very high reliability and safety.

System Reliability Analysis of Redundant Condition Monitoring Systems

The development and application of new reliability models and methods are presented to analyze the system relia- bility of complex condition monitoring systems.The methods include a method analyzing failure modes of a type of redundant con- dition monitoring systems (RCMS) by invoking failure tree model,Markov modeling techniques for analyzing system reliability of RCMS,and methods for estimating Markov model parameters.Furthermore,a computing case is investigated and many conclu- sions upon this case are summarized.Results show that the method proposed here is practical and valuable for designing condition monitoring systems and their maintenance.

GOMA:functional enrichment analysis tool based on GO modules

Analyzing the function of gene sets is a critical step in interpreting the results of high-throughput experiments in systems biology. A variety of enrichment analysis tools have been developed in recent years, but most output a long list of significantly enriched terms that are often redundant, making it difficult to extract the most meaningful functions. In this paper, we present GOMA, a novel enrichment analysis method based on the new concept of enriched functional Gene Ontology (GO) modules. With this method, we systematically revealed functional GO modules, i.e., groups of functionally similar GO terms, via an optimization model and then ranked them by enrichment scores. Our new method simplifies enrichment analysis results by reducing redundancy, thereby preventing inconsistent enrichment results among functionally similar terms and providing more biologically meaningful results.

Comparative Study on Structural Redundancy of Cable-Stayed and Extradosed Bridges Through Safety Assessment of Their Stay Cables

This study provides new insights into the comparison of cable-stayed and extradosed bridges based on the safety assessment of their stay cables.These bridges are often regarded as identical structures owing to the use of inclined cables;however,the international standards for bridge design stipulate different safety factors for stay cables of both types of bridges.To address this misconception,a comparative study was carried out on the safety factors of stay cables under fatigue and ultimate limit states by considering the effects of various untoward and damaging factors,such as overloading,cable loss,and corrosion.The primary goal of this study is to describe the structural disparities between both types of bridges and evaluate their structural redundancies by employing deterministic and nondeterministic methods.To achieve this goal,three-dimensional finite-element models of both bridges were developed based on the current design guidelines for stay cables in Japan.After the balanced states of the bridge models were achieved,static analyses were performed for different safety factors of stay cables in a parametric manner.Finally,the first-order reliability method and Monte Carlo method were applied to determine the reliability index of stay cables.The analysis results show that cable-stayed and extradosed bridges exhibit different structural redundancies for different safety factors under the same loading conditions.Moreover,a significant increase in structural redundancy occurs with an incremental increase in the safety factors of stay cables.

Self-alignment of full skewed RSINS: observability analysis and full-observable Kalman filter

Traditional orthogonal strapdown inertial navigation sys-tem （SINS） cannot achieve satisfactory self-alignment accuracy in the stationary base： taking more than 5 minutes and al the iner-tial sensors biases cannot get ful observability except the up-axis accelerometer. However, the ful skewed redundant SINS （RSINS） can not only enhance the reliability of the system, but also improve the accuracy of the system, such as the initial alignment. Firstly, the observability of the system state includes attitude errors and al the inertial sensors biases are analyzed with the global perspective method： any three gyroscopes and three accelerometers can be assembled into an independent subordinate SINS （sub-SINS）;the system state can be uniquely confirmed by the coupling connec-tions of al the sub-SINSs;the attitude errors and random constant biases of al the inertial sensors are observable. However, the ran-dom noises of the inertial sensors are not taken into account in the above analyzing process. Secondly, the ful-observable Kalman filter which can be applied to the actual RSINS containing random noises is established; the system state includes the position, ve-locity, attitude errors of al the sub-SINSs and the random constant biases of the redundant inertial sensors. At last, the initial self-alignment process of a typical four-redundancy ful skewed RSINS is simulated： the horizontal attitudes （pitch, rol ） errors and yaw error can be exactly evaluated within 80 s and 100 s respectively, while the random constant biases of gyroscopes and accelero-meters can be precisely evaluated within 120 s. For the ful skewed RSINS, the self-alignment accuracy is greatly improved, mean-while the self-alignment time is widely shortened.

Fault Detection and Isolation for Low Hardware Redundancy Flight Control System

The problems of current highly redundant flight control system are analyzed in this paper. Our study gives methods of utilizing other information to reduce physical components on the condition of meeting the reliability requirements for flight control system. The strategies presented in this paper mainly include information redundancy, multi-thread, time redundancy, geometry space redundancy, etc.. Analysis and simulation show these non-hardware based methods can reduce the requirement of system hardware level and thus reduce the system complexity, weight, space, costs and R＆D （research and development） time.

Canonical correlation analysis to land-use structure and its driving forces——Taking Yulin Prefecture as an example

In this paper, one of the most classical statistical methods, Canonical Correlation Analysis (CCA) is applied to identify quantitatively the driving forces of landuse structure in Yulin Prefecture. The main analysis is carried out through the software SPSS with the data on the level of towns and townships in 1992. The results indicate that landuse structure is determined by comprehensive action of different factors. Landuse structure with rural characteristics is mainly determined by geographical factors such as the elevation, temperature and precipitation, while the landuse structure with urban characteristics is mainly determined by demographic and socioeconomic conditions. At the same time, tests were carried out through the canonical correlation coefficient and redundancy analysis.

ANALYSIS OF Lyl1 EXPRESSION AS A FREQUENT PARTNER OF LMO2 IN T-CELL LEUKEMOGENESIS IN HUMAN

Objective： To identify aberrant gene expression in primary human T-cell acute lymphoblastic leukemia （T-ALL） and to evaluate the differently expressed level of Lyll and LMO2 genes in human LMO2 positive/TALl negative T-ALL tumors. Methods： Three methods, representational difference analysis （RDA） of cDNA, cDNA microarrays and RT-PCR were used to detect if Lyll and LMO2 genes were differently expressed in human LMO2 positive/tall negative T-ALL tumors. Results： The results of cDNA RDA and cDNA array shown that Lyll and LMO2 genes are differently expressed in human T-cell tumors. The result of RT-PCR also shown Lyll and LMO2 are high expressed in human T-cell tumors and very low level or no expressed in normal group. Conclusion： We have found that cDNA RDA and cDNA microarray can be successfully used to identify aberrant gene expression in T-ALL cells. In the study described in this manuscript we found that Lyll and LMO2 are aberrantly expressed in human T-ALL LMO2 positive/TALl negative T-ALL tumors.

Extending and analysis of X-Code

X-Code is one of the most important redundant array of independent disk （RAID）-6 codes which are capable of tolerating double disk failures. However, the code length of X-Code is restricted to be a prime number, and such code length restriction of X-Code limits its usage in the real storage systems. Moreover, as a vertical RAID-6 code, X-Code can not be extended easily to an arbitrary code length like horizontal RAID-6 codes. In this paper, a novel and efficient code shortening algorithm for X-Code is proposed to extend X-Code to an arbitrary length. It can be further proved that the code shortening algorithm maintains the maximum-distance-separable （MDS） property of X-Code, and namely, the shortened X-Code is still MDS code with the optimal space efficiency. In the context of the shortening algorithm for X-Code, an in-depth performance analysis on X-Code at consecutive code lengths is conducted, and the impacts of the code shortening algorithm on the performance of X-Code in various performance metrics are revealed.

Evaluation and Optimization of the Mixed Redundancy Strategy in Cloud-Based Systems

Mixed redundancy strategies are generally used in cloud-based systems,with different node switch mechanisms from traditional fault-tolerant strategies.Existing studies often concentrate on optimizing a single strategy in cloud computing environment and ignore the impact of mixed redundancy strategies.Therefore,a model is proposed to evaluate and optimize the reliability and performance of cloud-based degraded systems subject to a mixed active and cold standby redundancy strategy.In this strategy,node switching is triggered by a continual monitoring and detection mechanism when active nodes fail.To evaluate the transient availability and the expected job completion rate of systems with such kind of strategy,a continuous-time Markov chain model is built on the state transition process and a numerical method is used to solve the model.To choose the optimal redundancy for the mixed strategy under system constraints,a greedy search algorithm is proposed after sensitivity analysis.Illustrative examples were presented to explain the process of calculating the transient probability of each system state and in turn,the availability and performance of the whole system.It was shown that the near-optimal redundancy solution could be obtained using the optimizationmethod.The comparison with optimization of the traditional mixed redundancy strategy proved that the system behavior was different using different kinds of mixed strategies and less redundancy was assigned for the new type of mixed strategy under the same system constraint.

Probabilistic Indicators of Structural Redundancy in Mechanics

The paper in the introductory part reviews various definitions and interpretations of structural redundancy in mechanics. The study focuses on the general structural redundancy of systems after sequences of component failures followed by possible load redistributions. The second section briefly summarizes the Event Oriented System Analysis and structural redundancy in terms of the conditional probabilistic entropy. Mechanical responses to adverse loads in this approach are represented by random operational and failure events in the lifetime. The general redundancy measure in the third section of the paper employs the information entropy and goes beyond existing formulations since it includes all functional modes in service. The paper continues with a summary of traditional redundancy indices. In addition, it proposes an alternative redundancy index that accounts for the transition to secondary functional level in case of failures of primary components. The example of a ship structure illustrates the usage of the conditional entropy of subsystems of operational events and compares it to the traditional and newly proposed redundancy indices. The study at the end investigates how to enhance the safety of structures by using the redundancy based design.

珠江口伶仃洋春季鱼类群落结构及其与环境因子的RDA分析

为探究珠江口海域鱼类群落结构及其与环境因子的关系,于2021年3月在珠江口伶仃洋布设10个调查站位,分别在小潮期和大潮期开展鱼类底拖网调查和水环境数据收集,运用相对重要性指数、Shannon-Wiener多样性指数和Pielou均匀度指数研究鱼类群落结构,并通过冗余分析(redundancy analysis,RDA)探讨其与环境因子的相互关系。结果表明:本次调查到鱼类33种,隶属于13目(系)15科30属,其中小潮期捕获鱼类10目(系)12科22属23种,大潮期捕获鱼类12目(系)12科23属25种,有15种鱼类在2个时期均有捕获到;大潮期和小潮期各调查到鱼类优势种3种,其中凤鲚(Coilia mystus)和小头栉孔虾虎鱼(Ctenotrypauchen microcephalus)为共有优势种,颈斑鲾(Nuchequula nuchalis)为大潮期独有优势种,鳄鲬(Cociella crocodilus)为小潮期独有优势种;从生态习性看,2个潮期均为底层肉食性鱼类占优势;小潮期的Pielou均匀度指数在0.23~0.98之间,Shannon-Weiner多样性指数在0.77~2.44之间;大潮期的Pielou均匀度指数在0.39~0.86之间,Shannon-Weiner多样性指数在1.23~2.54之间;总体而言,大潮期鱼类物种数高于小潮期,但单因素方差分析(one-way analysis of variance,ANOVA)结果显示,大、小潮期的鱼类物种组成没有显著的差异(P=0.269)。RDA分析结果显示,水温、悬浮固体和叶绿素a是影响鱼类群落结构的主要环境因子。

基于高通量测序技术分析不同窖龄窖泥真菌群落多样性与空间异质性

利用Illumina NovaSeq高通量测序、冗余分析和FUNGuild等方法对甘肃金徽酒10a和50a窖龄窖池及其不同空间位置窖泥的真菌群落结构、真菌菌群与理化因子之间的关系以及真菌功能预测等进行研究。结果表明,随着窖池深度的增加,10 a窖池窖泥的多样性和丰富度呈现降低趋势,50 a窖池窖泥的多样性整体呈现升高趋势,而丰富度则呈现先降低后升高趋势,其中10a窖池窖壁上层的多样性和丰富度均显著高于其他位置(P<0.05),而50a窖池窖底层的多样性和丰富度均显著高于其他位置(P<0.05)。10a窖池窖壁层的多样性和丰富度显著高于50a窖池(P<0.05),而50a窖底层的多样性和丰富度明显高于10a窖池(P<0.05)。所有窖泥样品共检测到21个真菌门和520个真菌属,其中子囊菌门(Ascomycota)、担子菌门(Basidiomycota)、被孢霉门(Mortierellomycota)和罗兹菌门(Rozellomycota)4个优势真菌门以及曲霉属(Aspergillus)和哈萨克斯坦酵母属(Kazachstania)等多数优势真菌属的相对丰度随窖池窖龄和空间位置的变化差异显著(P<0.05)。镰刀霉属(Fusarium)、Aspergillus、Kazachstania和红曲霉属(Monascus)与水分、腐殖质、K^(+)和Ca^(2+)含量呈正相关,枝孢菌属(Cladosporium)、维希尼克氏酵母属(Vishniacozyma)与pH值呈正相关。窖泥真菌营养类型主要有腐生营养型和病理-腐生-共生营养型等7种,功能类群包括4个单一功能群和7个混合功能群。通过系统分析不同窖龄窖池和空间位置的窖泥真菌群落多样性,为明确甘肃金徽酒窖泥的真菌群落结构及空间分布规律奠定了理论基础。

2021年6月和9月唐山近岸海域浮游植物群落结构特征及影响因素

依据2021年6月和9月唐山近岸海域的生态现状调查数据,分析该海域浮游植物群落结构的时空变化特征及其影响因素。结果显示:2021年6月和9月共检出浮游植物3门39属79种;6月有4种优势种,以硅藻-甲藻混合占优;9月有5种优势种,均为硅藻;2个月无共有优势种。6月浮游植物丰度平均值为7.48×10^(4)个·m^(-3),9月为316.99×10^(4)个·m^(-3),浮游植物丰度的空间分布整体均表现出近岸高远岸低的分布趋势。聚类分析和多维尺度分析表明,2021年6月和9月唐山近岸海域浮游植物群落结构显著不同,物种演替明显,且6月浮游植物群落结构的差异性大于9月。冗余分析(RDA)显示,造成调查海域浮游植物群落结构6月和9月间存在显著差异的主要影响因素为盐度、温度、活性磷酸盐和悬浮物。6月海水环境特征为低温高盐水,磷酸盐质量浓度较低,而悬浮物质量浓度较高;9月海水环境特征为高温低盐水,活性磷酸盐较充足,悬浮物质量浓度较低。

基于冗余分析(RDA)的红树林水鸟物种组成特征及影响因子研究

在红树林生态系统中,水鸟多样性被认为是衡量红树林生态系统健康的重要指标。水鸟对环境因子的敏感性不同会导致其栖息地选择的差异,这些差异共同影响了红树林水鸟的物种多样性。开展红树林水鸟多样性及其影响因子分析,从景观尺度研究影响水鸟多样性的因子,可为广东省红树林生态系统健康评估及水鸟保护提供重要参考。文章分析了广东省红树林水鸟物种组成及动态变化,并应用冗余分析(Redundancy analysis,RDA)方法探讨了影响红树林水鸟多样性的因子及相关性。结果如下:(1)广东红树林水鸟物种数、国家重点保护物种数和香农指数分别由2018年的56种、10种和2.4921提升至2022年的88种、23种和2.7423;(2)RDA检验显示水鸟类群各典型轴对物种-景观因子关系方差的累积解释均超过96%,且蒙特卡罗排列检验具有显著性(p<0.05),说明前两个典型轴可以很好地解释水鸟物种与景观因子变量之间的相关性;(3)RDA分析表明红树林面积、滩涂面积和水产养殖池面积是影响水鸟多样性的正向因子,人为干扰因子如道路和建设用地面积是影响水鸟多样性的负向因子。

套养池塘主要养殖阶段浮游生物的群落结构特征

为探究长江中下游地区套养池塘主要养殖阶段浮游生物群落结构特征及其影响因素,于2019年5—9月,在中国水产科学研究院淡水渔业研究中心宜兴屺亭科研实验基地主养鲤(Cyprinus carpio,“福瑞鲤2号”)和尼罗罗非鱼(Oreochromis niloticus,“中威1号”)、套养鲢(Hypophthalmichthys molitrix)和鳙(H.nobilis),采用人工投喂的常规鱼种培育池塘中,每间隔15~25 d测定水体理化指标及浮游生物种类和数量。结果显示,主要养殖阶段池塘总氮和氨氮浓度呈上升趋势,并逐渐趋于稳定;亚硝酸氮含量在养殖周期内浓度均较低,总磷先上升、后下降。实验中共检测到浮游植物8门77属,以绿藻门和蓝藻门为主;浮游动物5类72种,以原生动物和轮虫类为主。基于浮游生物密度的主成分分析(PCA)和热图显示,实验期间浮游生物群落结构具有明显的时序性变化,优势种及其密度变化明显。冗余分析(RDA)表明,总氮和亚硝酸氮浓度显著影响浮游植物丰度(P<0.05);水温、p H和亚硝酸氮浓度显著影响浮游动物丰度(P<0.05)。14个浮游生物优势种的密度与水体理化指标间存在显著线性相关(P<0.05)。结果表明,长江中下游地区套养池塘主要养殖阶段浮游生物群落结构时序性变化明显,水体理化指标存在差异。本研究结果可为套养模式下池塘的水质监测和调控及养殖管理提供参考数据。

变电站系统抗震冗余性量化方法

为定量评价冗余性对变电站系统抗震性能的影响,提出了基于状态树方法的系统抗震冗余性分析方法.首先,在功能单元层面提出了冗余度、冗余效果指标、冗余系数的定义;其次,给出了系统冗余度的线性加权组合和非线性加权组合计算方法,将功能单元的冗余度和冗余系数进行集成;最后,建立了系统冗余度和冗余效果指标之间的关联模型.结果表明,变电站系统的抗震性能与其冗余度呈正相关性,系统冗余度-冗余效果指标模型可采用过原点直线表达,斜率为系统性能指标最大增量与系统最大冗余度的比值.母线单元具有汇集、分配电能的作用,对进线单元、变压器单元的冗余作用具有提升效果.采用线性加权和非线性加权组合计算方法时,变电站系统的最大冗余度分别为0.870和0.980,系统冗余度-冗余效果指标模型的斜率分别为0.698 9和0.618 1.

宁夏干旱风沙区荒漠草原不同退化阶段植被土壤变化特征及其相关性

为深入了解荒漠草原不同退化阶段植被与土壤变化,探究荒漠草原不同退化阶段土壤性质与植被特征的关系,本研究以宁夏干旱风沙区荒漠草原为对象,比较了未退化、轻度退化、中度退化和重度退化4个退化阶段下草地植被和土壤性状,分析了草地退化过程中植被与土壤的关系。结果表明:随草地退化程度增加,草地优势种由多年生豆科、禾本科逐渐转变为一年生杂类草;不同草地植物功能群盖度、高度和地上生物量随着退化加剧变化并不相同(P<0.05);Shannon-Wiener多样性指数、Simpson优势度指数和Pielou均匀度指数呈下降趋势;土壤有机质、全碳、全氮、速效氮、速效磷和黏粒含量显著降低,但容重显著增加。冗余分析发现,荒漠草原植被特征与土壤因子密切相关,不同退化阶段影响草地植被特征的土壤性质不同。未退化阶段,草地的植被特征受全碳含量极显著影响,中度退化阶段,草地的植被特征受容重含量极显著影响,重度退化阶段,草地的植被特征受速效氮含量极显著影响(P<0.01)。通过改善植被进而影响土壤或者补充土壤养分可能是一个有效的草地恢复策略。