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101.
While search engines have been a successful tool to search text information, image search systems still face challenges. The keyword-based query paradigm used to search in image collection systems, which has been successful in text retrieval, may not be useful in scenarios where the user does not have the precise way to express a visual query. Image collection exploration is a new paradigm where users interact with the image collection to discover useful and relevant pictures. This paper proposes a framework for the construction of an image collection exploration system based on kernel methods, which offers a mathematically strong basis to address each stage of an image collection exploration system: image representation, summarization, visualization and interaction. In particular, our approach emphasizes a semantic representation of images using kernel functions, which can be seamlessly harnessed across all system components. Experiments were conducted with real users to verify the effectiveness and efficiency of the proposed strategy.  相似文献   
102.
The vehicle routing problem with deliveries and pickups is one of the main problems within reverse logistics. This paper focuses on an important assumption that divides the literature on the topic, namely the restriction that all deliveries must be completed before pickups can be made. A generalised model is presented, together with a mathematical formulation and its resolution. The latter is carried out by adopting a suitable implementation of the reactive tabu search metaheuristic. Results show that significant savings can be achieved by allowing a mixture of delivery and pickup loads on-board and yet not incurring delays and driver inconvenience.  相似文献   
103.
The aim of this work was to study the accumulation and fractionation of P in the inlet and outlet sediment of a constructed wetland for the wastewater treatment of a metallurgic plant in Argentina. It was important to predict whether P could be released into the water again by changing environmental conditions or retained over time. P-fractionation was performed using a sequential extraction method. Sediment cores were sliced at depths of: 0-3; 3-7 and 7-10 cm. Sediment showed high pH values and anoxic conditions. In the inlet area, P was principally bound to the carbonate fraction, whereas in the outlet area, it was mainly bound in the residual fraction. This behavior was justified by the effluent composition, which is rich in Ca2+ and Fe3+ and presents high values of pH and conductivity. These conditions favor CaCO3 and Fe(OOH)n precipitation and the subsequent sorption of P to their surface. The sediment active layer involved in the exchange reactions was the superficial one (0-3 cm). The wetland is highly efficient in P retention. P was retained by sediment in fractions that will not release it to the water while chemical and environmental conditions of the system are maintained.  相似文献   
104.
随着现今社会互联网、个人终端技术的飞越发展,电子商务越来越多的出现在人们的生活与工作中,这种全新的商务模式具有便捷、高效率、低成本的特点.同时,这种全新的商务模式对管理水平、信息传递技术都提出了更高的要求,其中安全的重要性尤为突出.  相似文献   
105.
This paper presents Latency-Energy Minimization Medium Access (LEMMA), a new TDMA-based MAC protocol for Wireless Sensor Networks (WSNs), specially suited to extend the lifetime of networks supporting alarm-driven, delay-sensitive applications characterized by convergecast traffic patterns and sporadic traffic generation. Its cascading time-slot assignment scheme conciliates low end-to-end latency with a low duty-cycle, while supporting multi-sink WSN topologies. Unlike most of the current solutions, LEMMA’s time-slot allocation protocol makes decisions based on the interference actually experienced by the nodes, instead of following the simple but potentially ineffective n-hop approach. Simulation results are presented to demonstrate the ineffectiveness of the n-hop time-slot allocation in comparison with LEMMA, as well as to evaluate the performance of LEMMA against L-MAC, T-MAC and Low Power Listening. The results show that under the target scenario conditions, LEMMA presents lower interference between assigned time-slots and lower end-to-end latency, while matching its best contender in terms of energy-efficiency.  相似文献   
106.
Cable supported bridges are wind prone structures. Therefore, their aerodynamic behaviour must be studied in depth in order to guarantee their safe performance. In the last decades important achievements have been reached in the study of bridges under wind-induced actions. On the other hand, non-conventional design techniques such as sensitivity analysis or optimum design have not been applied although they have proved their feasibility in the automobile or aeronautic industries. The aim of this research work is to demonstrate how non-conventional design techniques can help designers when dealing with long span bridges considering their aeroelastic behaviour. In that respect, the comprehensive analytical optimum design problem formulation is presented. In the application example the optimum design of the challenging Messina Strait Bridge is carried out. The chosen initial design has been the year 2002 design proposal. Up to a 33% deck material saving has been obtained after finishing the optimization process.  相似文献   
107.
卷草纹是中国传统装饰纹样之一,它的形成和发展记载了中国装饰艺术旺盛的生命力。本文分析了卷草纹的发展过程、形象构成以及艺术特征,并通过具体案例诠释了它在现代设计各个领域的延展和应用。旨在探索传统装饰纹样在现代设计中的传承与发展的方向。  相似文献   
108.
文章阐述了地税网上申报系统开发的背景和意义;介绍了基于J2EE的网上报税系统的结构、软件的主要功能及具体的实现方法和所用的关键技术;总结了所用技术的优势以及系统中难点的处理。  相似文献   
109.
110.
Summary The transition of a poly(vinyl chloride) after either nucleophilic substitution to various extents or plasticization with distinct amounts of diocytl phthalate has been measured by Dynamical Mechanical Thermal Analysis. Both sets of experiments are shown to result in similar loss of transition. The results are argued in the light of prior work on the substitution mechanism determining role of the mmr chain segments at the end of isotactic sequences. They strongly suggest the mmr structures to interact specifically with plasticizer thereby becoming stiffer (antiplasticization).  相似文献   
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