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排序方式: 共有791条查询结果,搜索用时 15 毫秒
101.
In this study, a vehicle routing problem with hard time windows (VRPHTW) that appears to meet demands of customers’ service within time intervals in a supermarket chain is solved. In VRPHTW, to reach a solution by an exact method is quite difficult and sometimes impossible if number of constraints is large enough (i.e., NP-hard), and solution time of a VRPHTW grows exponentially. As the size of the problem grows, a near optimal solution can be found using a heuristic method. A hierarchical approach consisting of two stages as “cluster-first route-second” is proposed. In the first stage, customers are assigned to vehicles using three different clustering algorithms (i.e., K-means, K-medoids and DBSCAN). In the second stage, a VRPHTW is solved using a MILP. The main contribution of the article is that the proposed hierarchical approach enables us to deal with a large size real problem and to solve it in a short time using the exact method. Finally, the proposed approach is employed on a supermarket chain. An instance of the algorithm is demonstrated to illustrate the applicability of the proposed approach and the results obtained are highly favourable.  相似文献   
102.
This paper investigates the grindability of calcite powder (D50 = 6.68 µm) to submicron particle sizes using stirred media mill (0.75 l) and ultrasonic generator (400 W, 24 kHz). The present study focuses directly on the comminution of calcite powder in water media by combined stirred milling and ultrasonic treatment and effects of some operational parameters such as grinding time (10–30 min), ultrasonic power (40–100% µm as amplitude settings), and solid ratio (10–30% w/w) on comminution. Experimental results have been evaluated on the basis of product size and width of particle size distribution.  相似文献   
103.
This study presents the development process of a set of questionnaire items to establish a measurement model for the usability of shared workspace groupware systems, which is suggested as a usability scale called SWUS, the Shared Workspace Usability Scale. Manifest variables and latent variables are based on the various dimensions of teamwork collated through the literature. A structural model was built on the measurement model. Models were evaluated through PLS-SEM methods. Data acquired on candidate questionnaire items from 398 international respondents who are users of five different online collaborative word processors was used for the model analysis. Of 37 candidate manifest variables, 22 were retained, which were measuring seven latent constructs: “3C Mechanisms,” “Grounding,” “Team Integration,” “Communication,” “Shared Access,” “Awareness,” and “Usability.” The data provided empirical evidence for the structural model based on these latent variables. The responses of the participants were not sensitive to differences between users in terms of gender and native language but showed sensitivity to age, experience with the evaluated software, and different shared workspace groupware evaluated in the study. Our structural model attempts to integrate several frameworks and models of usability for CSCW environments and provides empirical evidence for its reliability and validity based on subjective responses from users of shared workspace groupware.  相似文献   
104.
Multimedia Tools and Applications - Evaluation of body temperature and thermal symmetry in neonates is important in monitoring health conditions and predicting potential risks. With thermography,...  相似文献   
105.
Nowadays, the Traveling Salesman Problem (TSP) is one of the most studied combinational optimization problems that researchers study. Although it is easy to define, its solution is hard. Therefore, it is one of the NP-hard problems in the research literature. It can be used to solve real-life problems such as route planning and scheduling, and transportation and logistics applications. In this study, for TSP, an interface that can run on mobile devices using Android and IOS operating systems is developed. Real-world data are used online by the interface. Locations, and the distance between them, are obtained instantly by Google Maps APIs. Genetic (GA) and ant colony optimization (ACO) algorithms are used to solve the TSP. Furthermore, users have also been allowed to conduct trials for different parameter values. The application developed has been tested on two different datasets. The test results show that for the determination of the optimum route, the ACO algorithm is better than the GA. However, when considering the run times, GA works much faster than ACO.  相似文献   
106.
Climate is among the most significant factors on the environmental performance, life span and/or durability of construction materials in buildings. Although some historical buildings have been abandoned and neglected for a very long period, their existence through centuries can be explained because of their durability to climatic conditions of the area where they are situated. In this study, construction techniques and characteristics of building materials used in some madrasas (historical education buildings) in Western Anatolia (Turkey) were examined in order to evaluate the conditions of the buildings by taking into account climatic conditions of the region. The studied Western Anatolian madrasas, which are in the moderate climatic conditions, were constructed out of rubble stone, brick and mortar in random bond with local workmanship by local builders who continued the older traditions and have survived for more than 300 years without maintenance and repair. On the other hand, most of the madrasa buildings in Central and Eastern Anatolia, which are in the steppe climatic conditions, were differently constructed with cut stone on their exterior surfaces to prevent the main structures of the walls composed of rubble stone and mortar from harsh climatic conditions of these regions. This study indicated that construction techniques and building materials appropriate to the climate might have been intentionally chosen for the survival of historical buildings over the centuries.  相似文献   
107.
Kaçar Y  Alpay E  Ceylan VK 《Water research》2003,37(5):1170-1176
In this study, pretreatment of Afyon (Turkey) alcaloide factory wastewater, a typical high strength industrial wastewater (chemical oxygen demand (COD)=26.65 kgm(-3), biological oxygen demand (BOD(5))=3.95 kgm(-3)), was carried out by wet air oxidation process. The process was performed in a 0.75 litre specially designed bubble reactor. Experiments were conducted to see the advantages of one-stage and two-stage oxidation and the effects of pressure, pH, temperature, catalyst type, catalyst loading and air or oxygen as gas source on the oxidation of the wastewater. In addition, BOD(5)/COD ratios of the effluents, which are generally regarded as an important index of biodegradability of a high-strength industrial wastewater, were determined at the end of some runs. After a 2h oxidation (T=150 degrees C, P=0.65 MPa, airflowrate=1.57 x 10(-5)m(3)s(-1), pH=7.0), the BOD(5)/COD ratio was increased from 0.15 to above 0.5 by using the salts of metals such as Co(2+),Fe(2+),Fe(2+)+Ni(2+),Cu(2+)+Mn(2+) as catalyst.  相似文献   
108.
The paper presents investigation of how the usage of bottom ash (BA), granulated blast furnace slag (GBFS), and combination of both of these materials as fine aggregate in concrete affects the concrete durability. To assess durability characteristics of concrete, durability tests were conducted and the results were evaluated comparing with reference concrete. Three series concrete were produced. GBFS, BA and GBFS+BA are replaced the 3–7 mm-sized aggregate. Five test groups were constituted with the replacement percentages as 10%, 20%, 30%, 40% and 50% in each series. These by-products were used as non-ground form in the concrete. Durability properties of the concretes were compared in order to study the possible advantages of different replacement ratios. According to results, GBFS and BA affects some durability properties of concrete positively in case of it is used as fine aggregate. Resistance to high temperature and surface abrasion are positively affected properties. Capillarity, drying-wetting and freezing-thawing resistance of the concrete can be accepted to some extent. Properties of by-products and its replacement ratio are controlling the influence level and direction. Comparison of the SEM images and test results show that chemical and physical properties of GBFS and BA are the main factors affecting the concrete durability. It is concluded that it is possible to produce durable concrete by using GBFS and BA as fine aggregate.  相似文献   
109.
A vision of change for innovation within the perspective of revaluing the construction industry is essential to develop a culture of self-sustaining improvement, mutual recognition, respect and support in the long term in North Cyprus. The research attempts to put forward a case for a restructuring of the construction sector in order to deliver a step in change in quality of output and to realise maximum value to all clients, stakeholders and end users. The main objective of this study is to (1) determine current innovation practices and identify key issues that contribute to successful implementation (2) assess the existence and severity of barriers to change for innovation (3) propose solutions for overcoming barriers to change for innovation in construction industry and develop a framework to revaluate the construction industry. The research includes an extensive literature study, interviews with managers on the challenge of change for innovation in construction, analysis of this information to develop findings, and extending these to present the key strategic issues that could be targeted for revaluing the construction industry. The paper commences on understanding the firms’ own processes and detecting their weaknesses and strengths, determining the strategies and actions that should be made in the short term to adopt innovation practices and helping the North Cyprus construction industry to learn as a whole. The paper concludes how the drivers of change for innovation can offer benefits to construction firms in North Cyprus if appropriate strategies are adopted.  相似文献   
110.
Dual phase steels are a class of steels characterized by a microstructure consisting of a soft ferrite matrix with hard martensite islands at the grain boundaries. The temperature in the dual phase (α + γ) region and the holding time are two important parameters in the intercritically annealing process. In this study, different grades of commercial low alloy steels have been heat treated to a constant annealing temperature by changing the holding time. It is observed that the effect of holding time is dependent on the steel composition. In this context, a microstructural examination has been carried out using optical, scanning electron microscope and electron probe micro-analysis and hardness values have been determined.  相似文献   
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