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.

冗余分析(RDA)在简化湖泊沉积指标体系中的应用——以太白湖为例

根据太白湖沉积柱中硅藻、孢粉、粒度、磁化率、元素含量等指标记录,冗余分析结果表明松孢粉的百分含量、沉积物磷浓度、频率磁化率及有机碳含量是能显著解释水环境变化的最小变量组合,解释的硅藻变率百分比达51.5%,仅比所有沉积指标共同解释的信息量少6.4%。主要根据该4指标的古环境意义,对该湖近200年来的营养演化驱动机制进行了探讨。太白湖近代富营养化过程表明:在温暖湿润的气候背景下,较高营养背景的湖泊极易在人类活动的驱动下发生富营养化,因此对湖泊资源必须进行合理的人为开发与利用。

稀有种处理对RDA排序结果影响的比较研究

为了解稀有种对RDA排序结果的影响,该研究以北京东灵山华北落叶松林调查数据为例,在RDA排序的基础上,对比分析了未处理稀有种RDA与剔除频度<5%、盖度<5%的稀有种后RDA排序结果的差异,并用蒙特卡罗拟合检验分析了二者物种变量和环境变量之间的相关关系,以及用Spearman秩相关系数检验了对应排序轴的相关性。结果表明:(1)蒙特卡罗拟合检验结果显示未处理稀有种RDA与剔除稀有种RDA各自对应的物种变量和环境变量之间均呈极显著相关关系;(2)从排序轴特征值对物种数据方差以及物种环境关系解释量来看,剔除稀有种RDA前两排序轴与前四排序轴均有较高的物种环境关系累积解释量;(3)剔除稀有种前后对应排序轴的Sperman秩相关分析结果表明,尽管未处理稀有种RDA和剔除稀有种RDA在第三轴和第四轴间存在一定的交叉,但二者对应的前四排序轴均呈极显著的一一对应关系(P<0.001),相似性极高。总之,结合物种环境关系的累积解释量及对应排序轴的相关性可知,在环境因子个数较少、研究尺度较小时,使用RDA排序揭示植物种、植物群落和环境因子之间相互作用的生态关系时,剔除稀有种前后RDA排序具有较高吻合性,只是对环境因子的解释趋势稍有差异。

用RDA技术寻找肝再生相关基因的初步研究

利用表达性差异显示分析 (RDA)技术 ,研究大鼠 2 /3肝部分切除后 1h肝组织中基因的选择性表达 ,建立了大鼠 2 /3肝部分切除术后 1h再生肝组织选择性表达基因EST库。该库约含 3× 10 4 个独立克隆 ,其中 95 %以上的克隆含有插入片段 ,长度约 2 0 0～ 70 0bp不等 ,对随机挑出的 5 2个克隆的序列分析表明其中大多数基因与肝再生调控相关 (38/5 2 )。 10株未报道序列经RNA杂交证实 ,其中 6株与肝再生相关。

基于RDA的白洋淀浮游植物群落动态特征分析

2010年4-11月采样调查了白洋淀浮游植物群落组成和时空变化特征,利用冗余分析（RDA）方法分析了影响浮游植物群落分布的主要环境因子.共检出浮游植物8门183种（属）,以蓝藻、绿藻和硅藻为主.浮游植物的密度在8.68×10^6-314.32×10^6/L内变化,最大值出现在秋季（9月）,最小值出现在冬季（11月）.采蒲台水体的Shannon-Wiener指数和均匀度指数最高,王家寨和南刘庄则较低.水温、透明度和高锰酸钾指数对白洋淀浮游植物群落的分布和动态变化影响最大,而pH值和总磷浓度对绿藻门和蓝藻门种类影响较为明显.控制有机污染物和磷的排放是解决白洋淀富营养化的主要措施.

CALIS、美、英、澳的RDA政策声明比较分析

选择具有代表性的中国高等教育文献保障系统(China Academic Library&Information System,CALIS)、美国、英国和澳大利亚的四个资源描述与检索(Resource Description and Access,RDA)政策声明为研究对象,从制定目的、排列方式和使用方式角度,着重分析了各政策声明的特点、规则条款数量、规则分布和做法类型以及本地核心元素的新增与分布,并以此为依据对中国RDA政策声明的制定提出建议。

荒漠草原弃耕恢复草地土壤与植被的RDA分析

土壤质量变劣是沙化的本质，核心内容为土壤物质流失，理化性质和生物特性退化，以及土体构型的变化。弃耕前土壤沙化程度和性质对弃耕地植被恢复进程、演替方向等产生重要影响。为了深入认识弃耕恢复草地不同覆沙厚度条件下，土壤环境因子和植物之间的关系，以宁夏盐池荒漠草原弃耕恢复草地为研究对象，应用冗余分析（ｒｅｄｕｎｄａｎｃｙａｎａｌｙｓｉｓＲＤＡ），研究弃耕恢复草地随地表覆沙厚度在空间上的连续变化，植被分布及其多样性变化与主要土壤因子间的关系。结果表明，１）随着覆沙厚度的增加植被由达乌里胡枝子群落向苦豆子群落转变；达乌里胡枝子的重要值由０．３３４降低到０．１０４，苦豆子的重要值由０增加到０．４０４。２）植物群落物种多样性指数从０．３２增加到０．７９，丰富度指数从０．１３增加到０．４０，均匀度指数从０．１１增加到０．２２。３）对弃耕地植物群落分布及其物种多样性变化有显著影响的主要土壤环境因子分别为碳酸钙和全盐（０～１０ｃｍ）、碳酸钙（１０～４０ｃｍ）。表层土壤碳酸钙含量的变化表征了地带性灰钙土的沙化程度和退化阶段，弃耕恢复草地当前植物分布格局的形成主要还是特定土壤退化状态约束下物种随机扩散竞争的适应性结果，覆沙厚度所决定的表层土壤环境因子的直接或间接作用是主要的决定因子，土壤养分对植被的直接作用尚未充分体现。

“资源描述与检索”(RDA)的实施进展

"资源描述与检索"(RDA)是一部应21世纪数字资源著录和信息描述的需要而诞生的元数据内容新标准。文章从宣传、培训、完善和与其他书目数据整合等角度对现阶段的RDA实施进展进行了调查与分析,并简要介绍了RDA在中国的发展情况。