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排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
Maarten Markus 《Planning Theory & Practice》2016,17(4):497-515
Frameworks of environmental regulations are fundamental yet problematic factors in achieving climate mitigation and adaptation policy goals. Recent theoretical arguments claim the value of general legal frameworks to enable experimentation and contextual adaptation of policies. However, empirical research regarding the effects of both general and specific norms in the practice of urban intervention remains limited. In this article we empirically discern how city governments deal with the tension between control and flexibility in the implementation of urban climate change goals. We argue that policies of adaptation/mitigation face two types of implementation problems: non-adaptive implementation and non-implementation. The first stems from an excessively constraining use of rules, while the second derives from a too general and undefined regulatory framework. Analysing two empirical cases in Amsterdam, Netherlands and Boston, MA, USA, we conclude that there are three elements that affect the way actors deal with these deficits: the level of scale at which regulations are established, the degree of land ownership which provides margin of manoeuvre to public authorities, and the sense of political urgency behind mitigation and adaptation policies. 相似文献
982.
Nonlinear clearing functions have been proposed in the literature as metamodels to represent the behaviour of production resources that can be embedded in optimisation models for production planning. However, most clearing functions tested to date use a single-state variable to represent aggregate system workload over all products, which performs poorly when product mix affects system throughput. Clearing functions using multiple-state variables have shown promise, but require significant computational effort to fit the functions and to solve the resulting optimisation models. This paper examines the impact of aggregation in state variables on solution time and quality in multi-item multi-stage production systems with differing degrees of manufacturing flexibility. We propose multi-dimensional clearing functions using alternative aggregations of state variables, and evaluate their performance in computational experiments. We find that at low utilisation, aggregation of state variables has little effect on system performance; multi-dimensional clearing functions outperform single-dimensional ones in general; and increasing manufacturing flexibility allows the use of aggregate clearing functions with little loss of solution quality. 相似文献
983.
通过中华商圣文化园的可行性方案的论证、规划、设计过程,侧重新型文化园的概念,以旅游文化为基调,建设集多种娱乐商业项目于一体的旅游文化商业园地。 相似文献
984.
985.
Based on a real case study from the automotive industry, this paper deals with production planning in powertrain plants. We present an overview of the production planning process and propose a mixed integer linear programme to determine the production quantities of each product over a planning horizon of several days. Then, using real data of an engine assembly line, we simulate the performance obtained through the proposed model within a rolling horizon planning process. We perform multiple tests in order to evaluate the impact of two parameters involved in this process: planning frequency and frozen horizon length. Furthermore, in order to illustrate the value of improving coordination between engine plants and their customers, we evaluate the impact of the quality of demand information (orders and forecasts). We analyse the simulation results and provide insights and recommendations in order to achieve a good trade-off between service level, inventory, and planning stability. 相似文献
986.
Daniele Martella Sara Nocentini Dmitry Nuzhdin Camilla Parmeggiani Diederik S. Wiersma 《Advanced materials (Deerfield Beach, Fla.)》2017,29(42)
Grabbing and holding objects at the microscale is a complex function, even for microscopic living animals. Inspired by the hominid‐type hand, a microscopic equivalent able to catch microelements is engineered. This microhand is light sensitive and can be either remotely controlled by optical illumination or can act autonomously and grab small particles on the basis of their optical properties. Since the energy is delivered optically, without the need for wires or batteries, the artificial hand can be shrunk down to the micrometer scale. Soft material is used, in particular, a custom‐made liquid‐crystal network that is patterned by a photolithographic technique. The elastic reshaping properties of this material allow finger movement, using environmental light as the only energy source. The hand can be either controlled externally (via the light field), or else the conditions in which it autonomously grabs a particle in its vicinity can be created. This microrobot has the unique feature that it can distinguish between particles of different colors and gray levels. The realization of this autonomous hand constitutes a crucial element in the development of microscopic creatures that can perform tasks without human intervention and self‐organized automation at the micrometer scale. 相似文献
987.
This paper focuses on the development and validation of an optimal motion planning method for computer-assisted surgical training. The context of this work is the development of new-generation systems that combine artificial intelligence and computer vision techniques in order to adjust the learning process to specific needs of a trainee, while preventing a trainee from the memorization of particular task settings. The problem described in the paper is the generation of shortest, collision-free trajectories for laparoscopic instrument movements in the rigid block world used for hand–eye coordination tasks. Optimal trajectories are displayed on a monitor to provide continuous visual guidance for optimal navigation of instruments. The key result of the work is a framework for the transition from surgical training systems in which users are dependent on predefined task settings and lack guidance for optimal navigation of laparoscopic instruments, to the so called intelligent systems that can potentially deliver the utmost flexibility to the learning process. A preliminary empirical evaluation of the developed optimal motion planning method has demonstrated the increase of total scores measured by total time taken to complete the task, and the instrument movement economy ratio. Experimentation with different task settings and the technical enhancement of the visual guidance are subjects of future research. 相似文献
988.
Automatic feature recognition aids downstream processes such as engineering analysis and manufacturing planning. Not all features can be defined in advance; a declarative approach allows engineers to specify new features without having to design algorithms to find them. Naive translation of declarations leads to executable algorithms with high time complexity. Database queries are also expressed declaratively; there is a large literature on optimizing query plans for efficient execution of database queries. Our earlier work investigated applying such technology to feature recognition, using a testbed interfacing a database system (SQLite) to a CAD modeler (CADfix). Feature declarations were translated into SQL queries which are then executed.The current paper extends this approach, using the PostgreSQL database, and provides several new insights: (i) query optimization works quite differently in these two databases, (ii) with care, an approach to query translation can be devised that works well for both databases, and (iii) when finding various simple common features, linear time performance can be achieved with respect to model size, with acceptable times for real industrial models. Further results also show how (i) lazy evaluation can be used to reduce the work performed by the CAD modeler, and (ii) estimating the time taken to compute various geometric operations can further improve the query plan. Experimental results are presented to validate our main conclusions. 相似文献
989.
This research located and analyzed forty case studies in Japan related to Enterprise Resource Planning (ERP) switching, and specifically discussed the Decline stage of the ERP Life Cycle which has not been concerned enough in the academia. Qualitative data was mainly collected to answer the research questions fully. The results indicate the Decline stage does exist empirically. The prior studies explore the ERP failure cases which usually happen soon after the kickoff. This research finds empirical evident that both Large Enterprises (LEs) and Small and Medium Enterprises (SMEs) have experienced some kinds of declining in system performance and business performance, and had the urges and needs to retire or upgrade the current ERP system. Based on the findings, the causes of ERP termination, the two strategies which organizations adopted to deal with the current ERP systems, and the five events after the decision-making point were summarized and discussed. The findings also revealed three ambiguous issues that need more efforts. The results of this research fill up the blank in the ERP life cycle theory for more than one decade. The findings from a relatively large sample can also help practitioners and researchers to explore the shifting period more thoroughly and to build tools to solve current and potential problems in order to prepare and assist organizations. 相似文献
990.
Susan L. Bradbury 《International Planning Studies》2016,21(1):64-80
Creating a continental transportation system that supports the efficient movement of goods between Canada and the United States is essential to the economies of both countries. However, 25 years after the passage of the Canada–US Free Trade Act and many agreements and accords later, poor connectivity, congestion and delays still plague many transborder corridors. Recent attempts to improve this situation involving several proposed new bridge projects have either been halted or significantly delayed over the last decade. This paper will review and critically examine the bi-national planning process that has been followed in an attempt to build a new bridge across the Detroit River, known as the Detroit River International Crossing (DRIC) project. 相似文献