Development and implementation of a NURBS curve motion interpolator

This paper deals with the issues of development and implementation of a real-time NURBS interpolator for a six-axis robot. Using an open-architecture controller system as a testbed, a real-time NURBS curve interpolator was developed, implemented and tested. Sample runs were conducted with the resulting trajectories measured in real-time during robot motion. The resulting trajectories are analyzed, discussed and compared with those from a commonly used point-to-point approximation technique. The real-time NURBS curve interpolator's feasibility, advantages and related issues are also discussed.     

Nonnegative integral subset representations of integer sets

We consider an integer-subset representation problem motivated by a medical application in radiation therapy. We prove NP-completeness, derive nontrivial bounds, and report on the performance of a greedy heuristic.     

Using the analytic network process (ANP) in a SWOT analysis - A case study for a textile firm

Strengths, Weaknesses, Opportunities and Threats (SWOT) analysis does not provide an analytical means to determine the importance of the identified factors or the ability to assess decision alternatives according to these factors. Although the analysis successfully pinpoints the factors, individual factors are usually described briefly and very generally. For this reason, SWOT analysis possesses deficiencies in the measurement and evaluation steps. Although the analytic hierarchy process (AHP) technique removes these deficiencies, it does not allow for measurement of the possible dependencies among the factors. The AHP method assumes that the factors presented in the hierarchical structure are independent; however, this assumption may be inappropriate in light of certain internal and external environmental effects. Therefore, it is necessary to employ a form of SWOT analysis that measures and takes into account the possible dependency among the factors. This paper demonstrates a process for quantitative SWOT analysis that can be performed even when there is dependence among strategic factors. The proposed algorithm uses the analytic network process (ANP), which allows measurement of the dependency among the strategic factors, as well as AHP, which is based on the independence between the factors. Dependency among the SWOT factors is observed to effect the strategic and sub-factor weights, as well as to change the strategy priorities.     

Information cut for clustering using a gradient descent approach

We introduce a new graph cut for clustering which we call the Information Cut. It is derived using Parzen windowing to estimate an information theoretic distance measure between probability density functions. We propose to optimize the Information Cut using a gradient descent-based approach. Our algorithm has several advantages compared to many other graph-based methods in terms of determining an appropriate affinity measure, computational complexity, memory requirements and coping with different data scales. We show that our method may produce clustering and image segmentation results comparable or better than the state-of-the art graph-based methods.     

A method for the efficient prioritization of infrastructure renewal projects

The infrastructure renewal program at MIT consists of a large number of projects with an estimated budget that could approach $1 billion. Infrastructure renewal at the Massachusetts Institute of Technology (MIT) is the process of evaluating and investing in the maintenance of facility systems and basic structure to preserve existing campus buildings. The selection and prioritization of projects must be addressed with a systematic method for the optimal allocation of funds and other resources. This paper presents a case study of a prioritization method utilizing multi-attribute utility theory. This method was developed at MIT's Department of Nuclear Engineering and was deployed by the Department of Facilities after appropriate modifications were implemented to address the idiosyncrasies of infrastructure renewal projects and the competing criteria and constraints that influence the judgment of the decision-makers. Such criteria include minimization of risk, optimization of economic impact, and coordination with academic policies, programs, and operations of the Institute. A brief overview of the method is presented, as well as the results of its application to the prioritization of infrastructure renewal projects. Results of workshops held at MIT with the participation of stakeholders demonstrate the feasibility of the prioritization method and the usefulness of this approach.     

Service life planning and performance requirements

Service life planning comprises a model for the determination of a reasonable expected service life for buildings and components, and it establishes a routine for the assessment of design alternatives. A design option is considered reasonable when it meets or exceeds performance requirements over time that have been drawn up specifically for the specific project. Due to this assessment reference, there is a very evident link to the concept of performance-based building. Any stakeholder involved in the value chain or in the design process of the building, as well as regulators and building users, can express performance requirements. Identified requirements, both in relevance and in quality, will vary with the stakeholder and his/her perspective of interest. As building sector manufacturers develop most products with reference to standards rather than with reference to specific requirements, there is no direct link from user requirements to the product design. Instead, the building designer has the responsibility to ensure performance requirements are met by the performance of products integrated into the design. As these design decisions also have to be made at the material and component level, a performance-based building would benefit from an established rationale that enables the communication of performance requirements across the relevant system levels in the relevant design processes. A path for the connection of the established concepts of service life planning and performance-based building is presented. The aim is to identify key elements that need to be developed for the successful linkage of performance-based building with service life planning.     

啮合型同向旋转双螺杆挤出螺槽非充满的熔融理论研究 Ⅱ.模型的求解

根据啮合型同向旋转双螺杆挤出非充满熔融的理论模型，对描述非充满熔融过程的主要物理量：固相高度变化函数、熔融速率及熔融区总长等进行了计算分析，并对有关影响因素进行了讨论。     

THE APPLICATION OF COKELET''''S WAVE THEORY IN THE CALCULATION OF WAVE-CURRENT FIELD

By using Cokelet's wave theory,the limiting wave height and the relative waveangular frequency in wave-current field were calculated in this paper.It is indicated by numeri-cal calculation that if the water depth is not too small,the result given by authors'calculationare very close to the results of limiting wave height by Dalrymple(1975)and to the data of rel-ative wave angular frequency by linear wave theory;but if water depth is rather small,thereare some discrepancy,     

压水堆核电厂用全自动多螺栓四同步安装机的结构创新研究

首先在结构上创造了新型螺栓、螺母和一套崭新的安装机。在主机上去掉了精密、复杂、昂贵的机器人或机械手，改用结构简单的集成齿轮机构，以实现同步旋拧功能；运用现代流体传动与控制的理论，建立流本控制的数学模型和传递函数，从而实现了4个同步安装的效果。