基于四自由度并联机构的数控机床研究

介绍一种基于混合型四自由度并联平台机构开发的五坐标并联机床 .由于其独特的机构设计 ,与基于 Stewart平台的并联机床相比 ,X方向的进给运动与运动平台分离 ,改由工作台单独进给 ,因而其工作空间成倍增大 .采用龙门框架结构和滚珠丝杠支承方案使机床获得更高的刚度 .给出了该机床运动学逆解 ,控制系统采用基于 PC的数控系统进行五轴联动控制

基于Stewart平台六维力传感器的分区静态标定方法

基于Stewart平台的六维力传感器具有结构紧凑、刚度大、量程宽等特点,它在工业机器人、空间站对接等领域具有广泛的应用前景。好的标定方法是正确使用传感器的基础。由于基于Stewart平台的六维力传感器是一个复杂的非线性系统,所以采用常规的线性标定方法必将带来较大的标定误差从而影响其使用性能。标定的实质是,由测量值空间到理论值空间的映射函数的确定过程。由函数逼近理论可知,当只在已知点集上给出函数值时,可用多项式或分段多项式等较简单函数逼近待定函数。基于上述思想,本文将整个测量空间划分为若干连续的子测量空间,再对每个子空间进行线性标定,从而提高了整个测量系统的标定精度。实验分析结果表明了该标定方法有效。

机器人多传感器实验平台中的图像传感器在线标定研究

本文结合智能机器人多传感器实验平台的研制工作,系统地介绍了图像传感器在线标定的原理和方法,并对标定系统的构成做了概述,同时结合实验对相关问题进行进一步的探讨。

基于跟随领航者法的多UUV队形控制方法研究

本文主要研究基于跟随领航者法的多 UUV(unmanned underwater vehicle)队形控制。在 UUV 载体坐标系下建立系统的运动学模型,该模型是对笛卡尔坐标系下的运动学模型的改进,避免了极坐标系下奇异点的出现。该模型经过输入输出反馈线性化,获得稳定的队形控制器。同时,为了缩小队形控制律中的控制参数的调整范围,本文提出了辅助算法,在此基础上分析参数的有效范围。将队形控制律在多 UUV 数字仿真平台上验证,证实了改进的运动学模型和控制律的有效性。

一种并联机床运动平台位姿测量方法

提出一种采用附加测量机构直接测量并联机床运动平台位姿精度的方法。其基本思想是根据运动平台的运动特性在固定平台和运动平台之间增设附加测量机构，当运动平台运动时带动测量机构运动，通过安装在测量机构上的传感器测得广义坐标参量， 经运动学建模即可得到运动平台的位姿。当测量机构位姿正解求解速度满足实时控制要求时，利用该反馈信息对机床进行实时精度补偿和控制。基于上述思想建立的并联机床位姿测量系统可部分排除机床切削力变形和运动副间隙等误差， 从而提高机床的位姿测量精度。以一种五坐标并联机床为例，介绍采用附加测量机构直接测量运动平台位姿精度的建模方法。其中， 测量机构的综合十分重要。测量机构的组成决定了运动学模型的复杂程度， 即决定了运动学模型的计算效率。

多种监控系统基于CAN总线的联网设计

介绍了基于CAN总线的多种监控系统联网设计,该设计应用DDE(动态数据交换)技术实现VB程序与多种组态软件开发的SCADA系统的数据交换,通过调用动态链接库函数完成总线的数据通信,从而搭建了工业现场的信息化管理平台.

藏东南巨厚松散堆积体发育条件、成灾模式及防治对策——以川藏公路然乌至鲁朗段为例

The unique geologic, geomorphic and climatic conditions of southeast Tibet have made the region to develop the multi-style and frequently occurring geologic hazards, especially the collapses and landslides and debris flows along the section of Ranwu-Lulang in Sichuan-Tibet highway. However, most of those geologic hazards have close relationship with the loose accumulations. That is, the loose accumulations are the main carrier of most geologic hazards. Thereof, the huge-thick accumulations along the highway is regarded as the objective in the thesis to study the geologic background, hazarding model and mitigation methods comprehensively, based on the multi-disciplinary theories and former materials. First of all, in the paper, based on field engineering geologic investigations, the genetic type and the characteristics of spatiotemporal distribution of the huge-thick loose accumulations along the highway, have been analysized from the factors of regional geology and geomorphy and climate, as well as the coupling acting of those factors with inoculation and eruption of the loose accumulations geologic hazards. The huge-thick loose accumulations has complex genetic types and specific regulations of spatiotemporal distribution, closely controlled by the outer environment of the region. The accumulations are composed of earth and boulder, with disorder structure and poor sorting, specific forming environments and depositing conditions. And its physical and mechanic properties are greatly distinguished from rock and common earth inland. When Sichuan-Tibet highway was firstly constructed along the north bank of Purlung Tsangpo River, the huge-thick loose accumulations was cut into many high and steep slopes. Through the survey to the cut-slopes and systematic investigation to their failures, the combination of height and angle of the accumulations slope has been obtained. At the same time, the types of genetic structure of those cut-slopes are also analysized and concluded, as well as their failure models. It is studied in the paper that there are piaster, duality, multielement and complexity types in genetic structure, and rip-dump-repose, rip-shear-slip and weathering-flake types in failure models. Moreover, it is briefly introduced present engineering performance methods and techniques dealing with the deformation and failure of the accumulations cut-slope. It is also suggested that several new techniques of slope enforcement and the method of landslide and rockfall avoiding should be applied. The research of high and steep cut-slope along the highway has broadened the acknowledgement of the combination of cut-slope height and angle. Especially, the dissertation also has made the monographic studies about the geologic background and hazarding models and prevention methods of some classic but difficult accumulations geologic hazards. They are: (1) Research of the engineering geologic background of the 102 landslide group and key problems about the project of tunnel. The 102 landslide group is a famous accumulational one composed of glacial tills and glaciofuvial deposit. The tunnel project is a feasible and optional one which can solve the present plight of “sliding after just harnessing” in the 102 section. Based on the glacial geomorphy and its depositing character, distribution of seepage line, a few drillhole materials and some surveying data, the position of contact surface between gneiss and accumulations has been recognized, and the retreating velocities of three different time scales (short, medium and long term) have been approximately calculated, and the weathering thickness of gneiss has also been estimated in the paper. On the basis of above acknowledgement, new engineering geomechnic mode is established. Numerical analysis about the stability of the No.2 landslide is done by way of FLAC program, which supplies the conclusion that the landslide there develops periodically. Thereof, 4 projects of tunnel going through the landslide have been put forwards. Safety distance of the tunnel from clinohefron has been numerically analysized. (2) Research of the geologic setting and disaster model and hazard mitigation of sliding-sand-slope. From the geologic setting of talus cone, it is indicated that the sliding-sand-slope is the process of the re-transportation and re-deposit of sand under the gravity action and from the talus cone. It is the failure of the talus cone essentially. The layering structure of the sliding-sand-slope is discovered. The models of movement and failure of the sliding-sand-slope has been put forwards. The technique, “abamurus+grass-bush fence+degradable culture pan”, is suggested to enforcement and green the sliding-sand-slope. (3) Characteristics and hazarding model and disaster mitigation of debris flow. The sources of solid material of three oversize debris flows have been analysized. It is found that a large amount of moraine existing in the glacial valley and large landslide dam-break are the two important features for oversize debris flow to be taken place. The disaster models of oversize and common debris flows have been generalized respectively. The former model better interpret the event of the Yigong super-large landslide-dam breaking. The features of common debris flow along the highway section, scouring and silting and burying and impacting, are formulated carefully. It is suggested that check dam is a better engineering structure to prevent valley from steeply scouring by debris flow. Moreover, the function of check dam in enforcing the slope is numerically calculated by FLAC program. (4) Songzong ancient ice-dammed lake and its slope stability. The lacustrine profile in Songzong landslide, more than 88 meters thick, is carefully described and measured. The Optical Simulated Luminescence (OSL) ages in the bottom and top of the silty clay layer are 22.5±3.3 kaB.P., 16.1±1.7 kaB.P., respectively. It is indicated by the ages that the lacustrine deposits formed during the Last Glacial Maximum ranging from 25ka B.P. to 15ka B.P. The special characteristics of the lacustrine sediment and the ancient lake line in Songzong basin indicated that the lacustrine sediment is related to the blocking of the Purlung Tsangpo River by the glacier in Last Glacial Maximum from Dongqu valley. The characteristics of the lacustrine profile also indicate that the Songzong ice-dammed lake might run through the Last Glacial Maximum. Two dimensional numerical modeling and analysis are done to simulate the slope stability under the conditions of nature and earthquake by FLAC program. The factor of safety of the lacusrtine slope is 1.04, but it will take place horizontal flow under earthquake activity due to the liquefaction of the 18.33 m silt layer. The realign to prevent the road from landslide is suggested.

巴丹吉林沙漠及其南缘地区的水化学和环境同位素特征与环境演变

The Badain Jaran Desert lies on the Alashan Plateau in western Inner Mongolia. Because of huge dunes, permanent lakes and on the northern fringe of the Asian summer monsoon, the Badain Jaran Desert has been drawing attentions of many experts. And they have made great progress in dune’s geomorphology, botany in desert, paleoclimate change and other study areas. We analyzed environmental isotope and ion chemistry in lakes and groundwater of the desert and southeastern area, and collected some other evidences from 14C dating, fossils and archeology. According to chemical analysis, we discuss the difference spatial character of ion chemistry and environmental isotope in lakes and groundwater of the desert and adjacent. Contrasting with ion chemistry and isotope results in other arid area, we argue origin of groundwater and lakes in the desert area, and get a preliminary understanding of desert lakes’ evolution during Holocene. Some main conclusions were drawn as follows: 1. It has a obvious difference in hydrophysical parameters between lakes and groundwater in the desert and margin. 2. The results of ion analysis show that Na+ and Cl- are dominant in most lakes of the desert. Meanwhile, Na+ 、Cl- and HCO3- are dominant in groundwater of the desert and adjacent, and alsoMg2+、Ca2+、and NO3- have more percentage than in lakes. 3. Owing to different solubilities, the conten of main ions in water varies with the content of TDS. Whereas the content of TDS is over 100 g/L, the content of SO42-、HCO3-、Mg2+and Ca2+ in lakes descend. 4. The result of isotope analyzing indicate the lakes and groundwater in southeast desert have a similar vaporing trend with the groundwater in the southeast margin of the desert. It imply there would have some kind of contact between groundwater in margin and lakes of southeast desert. 5. Contrasting with isotope results of groundwater in other arid area, it show that the groundwater in the desert and Yabulai area should be phreatic water which have a low water table. Therefore, we conclude that the groundwater in southeast part of the desert and southern margin mainly are recharged by precipitation of local abundant rainfall and groundwater of low mountain of southern area. 6. And all of these evidences, which are different from salinity, the content of CO32- and geological data, show that the bigger northern lake group and southeastern lake group in the desert have different groundwater replenishing system because a fold belt lie between of the two group lakes and obstruct them in landform. and HCO3- 7. The 14C dating results of fossil and lacustrine deposits show that there maybe have a wider range of shoreline during early and middle Holocene than today. 8. By the discovery and study of some pieces of pottery and fine stoneware, we preliminary conclude that there maybe have some certain amount of early human activities in the Badain Jaran Desert.

Series Elastic Actuators

This thesis presents the design, construction, control and evaluation of a novel force controlled actuator. Traditional force controlled actuators are designed from the premise that "Stiffer is better''. This approach gives a high bandwidth system, prone to problems of contact instability, noise, and low power density. The actuator presented in this thesis is designed from the premise that "Stiffness isn't everything". The actuator, which incorporates a series elastic element, trades off achievable bandwidth for gains in stable, low noise force control, and protection against shock loads. This thesis reviews related work in robot force control, presents theoretical descriptions of the control and expected performance from a series elastic actuator, and describes the design of a test actuator constructed to gather performance data. Finally the performance of the system is evaluated by comparing the performance data to theoretical predictions.

The Grasping Problem: Toward Task-Level Programming for an Articulated Hand

This report presents a system for generating a stable, feasible, and reachable grasp of a polyhedral object. A set of contact points on the object is found that can result in a stable grasp; a feasible grasp is found in which the robot contacts the object at those contact points; and a path is constructed from the initial configuration of the robot to the stable, feasible final grasp configuration. The algorithm described in the report is designed for the Salisbury hand mounted on a Puma 560 arm, but a similar approach could be used to develop grasping systems for other robots.

Novel information sharing syntax for data sharing between police and community partners, using role-based security.

The exchange of information between the police and community partners forms a central aspect of effective community service provision. In the context of policing, a robust and timely communications mechanism is required between police agencies and community partner domains, including: Primary healthcare (such as a Family Physician or a General Practitioner); Secondary healthcare (such as hospitals); Social Services; Education; and Fire and Rescue services. Investigations into high-profile cases such as the Victoria Climbié murder in 2000, the murders of Holly Wells and Jessica Chapman in 2002, and, more recently, the death of baby Peter Connelly through child abuse in 2007, highlight the requirement for a robust information-sharing framework. This paper presents a novel syntax that supports information-sharing requests, within strict data-sharing policy definitions. Such requests may form the basis for any information-sharing agreement that can exist between the police and their community partners. It defines a role-based architecture, with partner domains, with a syntax for the effective and efficient information sharing, using SPoC (Single Point-of-Contact) agents to control in-formation exchange. The application of policy definitions using rules within these SPoCs is inspired by network firewall rules and thus define information exchange permissions. These rules can be imple-mented by software filtering agents that act as information gateways between partner domains. Roles are exposed from each domain to give the rights to exchange information as defined within the policy definition. This work involves collaboration with the Scottish Police, as part of the Scottish Institute for Policing Research (SIPR), and aims to improve the safety of individuals by reducing risks to the community using enhanced information-sharing mechanisms.

Opções terapêuticas no encerramento de diastemas

Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária

Lower extremity amputation in people with diabetes: Trends and determinants

Introduction: The prevalence of diabetes is rising rapidly. Assessing quality of diabetes care is difficult. Lower Extremity Amputation (LEA) is recognised as a marker of the quality of diabetes care. The focus of this thesis was first to describe the trends in LEA rates in people with and without diabetes in the Republic of Ireland (RoI) in recent years and then, to explore the determinants of LEA in people with diabetes. While clinical and socio-demographic determinants have been well-established, the role of service-related factors has been less well-explored. Methods: Using hospital discharge data, trends in LEA rates in people with and without diabetes were described and compared to other countries. Background work included concordance studies exploring the reliability of hospital discharge data for recording LEA and diabetes and estimation of diabetes prevalence rates in the RoI from a nationally representative study (SLAN 2007). To explore determinants, a systematic review and meta-analysis assessed the effect of contact with a podiatrist on the outcome of LEA in people with diabetes. Finally, a case-control study using hospital discharge data explored determinants of LEA in people with diabetes with a particular focus on the timing of access to secondary healthcare services as a risk factor. Results: There are high levels of agreement between hospital discharge data and medical records for LEA and diabetes. Thus, hospital discharge data was deemed sufficiently reliable for use in this PhD thesis. A decrease in major diabetes-related LEA rates in people with diabetes was observed in the RoI from 2005-2012. In 2012, the relative risk of a person with diabetes undergoing a major LEA was 6.2 times (95% CI 4.8-8.1) that of a person without diabetes. Based on the systematic review and meta-analysis, contact with a podiatrist did not significantly affect the relative risk (RR) of LEA in people with diabetes. Results from the case-control study identified being single, documented CKD and documented hypertension as significant risk factors for LEA in people with diabetes whilst documented retinopathy was protective. Within the seven year time window included in the study, no association was detected between LEA in patients with diabetes and timing of patient access to secondary healthcare for diabetes management. Discussion: Many countries have reported reduced major LEA rates in people with diabetes coinciding with improved organisation of healthcare systems. Reassuringly, these first national estimates in people with diabetes in the RoI from 2005 to 2012 demonstrated reducing trends in major LEA rates. This may be attributable to changes in diabetes care and also, secular trends in smoking, dyslipidaemia and hypertension. Consistent with international practice, LEA trends data in Ireland can be used to monitor quality of care. Quantifying this improvement precisely, though, is problematic without robust denominator data on the prevalence of diabetes. However, a reduction in major diabetes-related LEA rates suggests improved quality of diabetes care. Much controversy exists around the reliability of hospital discharge data in the RoI. This thesis includes the first multi-site study to explore this issue and found hospital discharge data reliable for the reporting of the procedure of LEA and diagnosis of diabetes. This project did not detect protective effects of access to services including podiatry and secondary healthcare for LEA in people with diabetes. A major limitation of the systematic review and meta-analysis was the design and quality of the included studies. The data available in the area of effect of contact with a podiatrist on LEA risk are too sparse to say anything definitive about the efficacy of podiatry on LEA. Limitations of the case-control study include lack of a diabetes register in Ireland, restricted information from secondary healthcare and lack of data available from primary healthcare. Due to these issues, duration of disease could not be accounted for in the study which limits the conclusions that can be drawn from the results. The model of diabetes care in the RoI is currently undergoing a re-configuration with plans to introduce integrated care. In the future, trends in LEA rates should be continuously monitored to evaluate the effectiveness of changes to the healthcare system. Efforts are already underway to improve the availability of routine data from primary healthcare with the recent development of the iPCRN (Irish Primary Care Research Network). Linkage of primary and secondary healthcare records with a unique patient identifier should be the goal for the future.

The mobile cloud - more than a cloud

Nearly one billion smart mobile devices are now used for a growing number of tasks, such as browsing the web and accessing online services. In many communities, such devices are becoming the platform of choice for tasks traditionally carried out on a personal computer. However, despite the advances, these devices are still lacking in resources compared to their traditional desktop counterparts. Mobile cloud computing is seen as a new paradigm that can address the resource shortcomings in these devices with the plentiful computing resources of the cloud. This can enable the mobile device to be used for a large range of new applications hosted in the cloud that are too resource demanding to run locally. Bringing these two technologies together presents various difficulties. In this paper, we examine the advantages of the mobile cloud and the new approaches to applications it enables. We present our own solution to create a positive user experience for such applications and describe how it enables these applications.

Stress correlations in granular materials: An entropic formulation

We study the response of dry granular materials to external stress using experiment, simulation, and theory. We derive a Ginzburg-Landau functional that enforces mechanical stability and positivity of contact forces. In this framework, the elastic moduli depend only on the applied stress. A combination of this feature and the positivity constraint leads to stress correlations whose shape and magnitude are extremely sensitive to the nature of the applied stress. The predictions from the theory describe the stress correlations for both simulations and experiments semiquantitatively. © 2009 The American Physical Society.