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1.
Highway design which ensures that successive elements are coordinated in such a way as to produce harmonious and homogeneous driver performances along the road is considered consistent and safe. On the other hand, an alignment which requires drivers to handle high speed gradients and does not meet drivers' expectancy is considered inconsistent and produces higher crash frequency.  相似文献   
2.
Computer Numerical Control Machine Tool (CNCMT) Digital Twin (DT) model is a carrier for complex, time-varying, coupled data of CNCMT, which can theoretically provide a time-varying high-fidelity model. However, there are still many difficulties in its implementation process. And the key issue is how to realize the updated DT model with performance attenuation and validate it. In order to solve this problem, a model consistency retention method for CNCMT DT model is studied and proposed in this paper. Firstly, the framework of consistency retention method for DT model is designed including both digital space and physical space. The principles of data management and performance attenuation update in digital space are elaborated. Then, the implementation method for consistency retention of CNCMT DT model is studied in terms of performance attenuation update workflow for wear and other damage separately. Finally, a case study for the establishment and application of high-fidelity test bench DT model that focusing on rolling guide-rail is carried out to show the implementation flow of the proposed method and verify its operability and effectiveness.  相似文献   
3.
Micro electro discharge machining (micro EDM) is suitable for machining micro holes on metal alloy materials, and the micro holes can be machined even to several microns by use of wire electro discharge grinding (WEDG) of micro electrodes. However, considering practicability of micro holes <Φ100 μm in batch processing, the controllable accuracy of holes’ diameter, the consistency accuracy of repeated machining and the processing efficiency are required to be systematically improved. On the basis of conventional WEDG method, a tangential feed WEDG (TF-WEDG) method combined with on-line measurement using a charge coupled device (CCD) was proposed for improving on-line machining accuracy of micro electrodes. In TF-WEDG, removal resolution of micro-electrode diameter (the minimum thickness to be removed from micro electrode) is greatly improved by feeding the electrode along the tangential direction of wire-guide arc, and the resolution is further improved by employing negative polarity machining. Taking advantage of the high removal resolution, the precise diameter of micro-electrode can be achieved by the tangential feed of electrode to a certain position after diameter feedback of on-line measurement. Furthermore, a hybrid process was presented by combining the TF-WEDG method and a self-drilled holes method to improve the machining efficiency of micro electrodes. A cyclic alternating process of micro-electrode repeated machining and micro holes’ drilling was implemented for array micro holes with high consistency accuracy. Micro-EDM experiments were carried out for verifying the proposed methods and processes, and the experimental results show that the repeated machining accuracy of micro electrodes was less than 2 μm and the consistency accuracy of array micro holes was ±1.1 μm.  相似文献   
4.
In manufacturing industries, images are commonly used for quality control purposes. In such applications, if the quality of the products is good, then their images should be all similar to the image of a good-quality product. Therefore, comparison of images is a fundamental task in image-based quality control. This problem, however, is complicated in the sense that (1) observed images often contain noise, and (2) the related images need to be geometrically matched up first because images of different products could be geometrically mismatched because the relative positions between a camera and different products are often not exactly the same. The first issue requires a statistical method that can remove noise, and the second issue is related to the so-called image registration problem in the image processing literature. In this article, we propose effective methods for detecting difference between two images of products, and our proposed methods can accommodate both noise and geometric mismatch mentioned above. Theoretical results and numerical examples show that they can work effectively in applications.  相似文献   
5.
Complex socio-technical systems pose considerable challenges to requirements elicitation due to dynamic boundary conditions and conflicting perspectives. Traditional requirements engineering is criticized for its failure in providing a systemic view, overlooking ethical concerns and marginalized social perspectives. It is argued that educational institutions as a part of society need to ethically develop and manage their academic processes and consider such perspectives for emancipation. This critical qualitative research applies the emancipatory systemic methodology of critical systems thinking (CST) for the requirements elicitation of a complex and dynamic university course-timetables management problem. Firstly, the problem is ethically formulated to mitigate Type III errors. Secondly, multiple viewpoints are sought for boundary judgments using a CST-based ethical inquiry of boundary critique to reveal the normative content of the project design, explore imbalances amongst the socio-technical design components, and unveil the underlying ethical issues. The dynamic stakeholder network captures the system's emergence through stakeholder interconnectedness and boundary liquidity by sweeping-in relevant stakeholders through the continuum of various states of the project. This work enlightens requirements engineering by coupling systemic and socio-technical lenses for the elicitation of ethical requirements and the emancipation of marginalized perspectives in complex and dynamic information systems projects in general and timetabling problems, in particular.  相似文献   
6.
ContextOrganisational reengineering, continuous process improvement, alignment among complementary analysis perspectives, and information traceability are some current motivations to promote investment and scientific effort for integrating goal and business process perspectives. Providing support to integrate information systems analysis becomes a challenge in this complex setting.ObjectiveThe GoBIS framework integrates two goal and business process modelling approaches: i (a goal-oriented modelling method) and Communication Analysis (a communication-oriented business process modelling method).MethodIn this paper, we describe the methodological integration of both methods with the aim of fulfilling several criteria: i) to rely on appropriate theories; ii) to provide abstract and concrete syntaxes; iii) to provide scenarios of application; iv) to develop tool support; v) to provide demonstrable benefits to potential adopters.ResultsWe provide guidelines for using the two modelling methods in a top-down analysis scenario. The guidelines are validated by means of a comparative experiment and a focus-group session with students.ConclusionsFrom a practitioner viewpoint (modeller and/or analyst), the guidelines facilitate the traceability between goal and business process models, the experimental results highlight the benefits of GoBIS in performance and usability perceptions, and demonstrate an improvement on the completeness of the latter having an impact on efficiency. From a researcher perspective, the validation has produced useful feedback for future research.  相似文献   
7.
This study aims to investigate the effect of mica content on the mechanical properties of clays.Commercially available ground mica was blended with a locally available clayey soil,at varying nica contents by mass of 5%,10%,15%,20%,25% and 30%,to artificially prepare various micaceous clay blends.The preliminary testing phase included consistency limits and standard Proctor compaction tests.The primary testing program consisted of unconfined compression(UC),direct shear(DS) and scanning electron microscopy(SEM) tests.The test results showed that the liquid and plastic limits exhibited a linear,monotonically increasing trend with increase in mica content.The rate of increase in the plastic limit,however,was found to be greater than that of the liquid limit,thereby leading to a gradual transition towards a non-plastic,cohesionless character.The soft,spongy fabric and high water demand of the mica mineral led to higher optimum water contents and lower maximum dry unit weights with increasing mica content.Under low confinement conditions,i.e.the UC test and the DS test at low normal stresses,the shear strength was adversely affected by mica.However,the closer packing of the clay and mica components in the matrix under high confinement conditions offsets the adverse effects of mica by inducing frictional resistance at the shearing interface,thus leading to improved strength resistance.  相似文献   
8.
目的采用国家食品标准与三标度层次分析法(TAHP)对新疆小麦粉和食用植物油进行风险评估。方法层次构建中采用三标度(0,1,2)定量确定各个有害物的危害程度,并建立相应的比较和判断矩阵。通过矩阵运算获得各个危害物的权重并进行一致性检验。结果采用TAHP在MATLAB软件的辅助下计算各有害物的权重并检验其一致性。一致性检验结果为小麦粉为0.089,4种植物油为0.085,均低于0.1。利用各危害物权重因子构建的风险模型分别运用于新疆小麦粉和食用植物油2010、2014和2015年的风险评估,结果与实际情况较为吻合。结论该风险模型不仅可应用于上述食品质量风险评估,而且还可推广应用于其他食品的安全评价模型的构建,以及对食品质量安全的调查、评估和监督提供参考。  相似文献   
9.
叶永  陈建峰  程萍  冷欣 《传感技术学报》2012,25(11):1507-1510
在使用TDOA算法进行被动声定向时,为精确获取麦克风阵列阵元之间接收声源信号的时间差,进而计算目标的方位角,麦克风阵元之间必须保持较高的相位一致性。而从论文与专利检索来看,目前还没有有效方法筛选出符合要求的麦克风阵元。针对此问题,本文基于麦克风阵列阵元相位一致性的指标,设计出麦克风阵元筛选系统,通过实测数据分析表明:一致性较高的麦克风更适合组建麦克风阵列。  相似文献   
10.
Abstract:

A prioritization process has been developed and used at Network Systems of BAE Systems. It has been used to derive weights of importance for the criteria in tradeoff studies and to prioritize goals, customer needs, capabilities, risks, directives, initiatives, issues, activities, requirements, technical performance measures, features, functions and value engineering activities. This article presents this prioritization process.  相似文献   
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