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81.
Conventional adaptive driving beam headlamps are limited in achieving still higher quantities of switchable pixels by the number of LEDs and movable elements needed. In this paper, it is shown that by integrating an active matrix liquid crystal display module, it is possible to realize fully adaptive high‐resolution headlights without mechanical elements and a finite number of LED with 30 k switchable pixels.  相似文献   
82.
World Wide Web is a continuously growing giant, and within the next few years, Web contents will surely increase tremendously. Hence, there is a great requirement to have algorithms that could accurately classify Web pages. Automatic Web page classification is significantly different from traditional text classification because of the presence of additional information, provided by the HTML structure. Recently, several techniques have been arisen from combinations of artificial intelligence and statistical approaches. However, it is not a simple matter to find an optimal classification technique for Web pages. This paper introduces a novel strategy for vertical Web page classification, which is called Classification using Multi-layered Domain Ontology (CMDO). It employs several Web mining techniques, and depends mainly on proposed multi-layered domain ontology. In order to promote the classification accuracy, CMDO implies a distiller to reject pages related to other domains. CMDO also employs a novel classification technique, which is called Graph Based Classification (GBC). The proposed GBC has pioneering features that other techniques do not have, such as outlier rejection and pruning. Experimental results have shown that CMDO outperforms recent techniques as it introduces better precision, recall, and classification accuracy.  相似文献   
83.
With quantum computers being out of reach for now, quantum simulators are alternative devices for efficient and accurate simulation of problems that are challenging to tackle using conventional computers. Quantum simulators are classified into analog and digital, with the possibility of constructing “hybrid” simulators by combining both techniques. Here we focus on analog quantum simulators of open quantum systems and address the limit that they can beat classical computers. In particular, as an example, we discuss simulation of the chlorosome light-harvesting antenna from green sulfur bacteria with over 250 phonon modes coupled to each electronic state. Furthermore, we propose physical setups that can be used to reproduce the quantum dynamics of a standard and multiple-mode Holstein model. The proposed scheme is based on currently available technology of superconducting circuits consist of flux qubits and quantum oscillators.  相似文献   
84.
In this paper, we present some novel results and ideas for robust and accurate implicit representation of geometric surfaces in finite element analysis. The novel contributions of this paper are threefold: (1) describe and validate a method to represent arbitrary parametric surfaces implicitly; (2) represent arbitrary solids implicitly, including sharp features using level sets and boolean operations; (3) impose arbitrary Dirichlet and Neumann boundary conditions on the resulting implicitly defined boundaries. The methods proposed do not require local refinement of the finite element mesh in regions of high curvature, ensure the independence of the domain’s volume on the mesh, do not rely on boundary regularization, and are well suited to methods based on fixed grids such as the extended finite element method (XFEM). Numerical examples are presented to demonstrate the robustness and effectiveness of the proposed approach and show that it is possible to achieve optimal convergence rates using a fully implicit representation of object boundaries. This approach is one step in the desired direction of tying numerical simulations to computer aided design (CAD), similarly to the isogeometric analysis paradigm.  相似文献   
85.
Clustering algorithms generally accept a parameter k from the user, which determines the number of clusters sought. However, in many application domains, like document categorization, social network clustering, and frequent pattern summarization, the proper value of k is difficult to guess. An alternative clustering formulation that does not require k is to impose a lower bound on the similarity between an object and its corresponding cluster representative. Such a formulation chooses exactly one representative for every cluster and minimizes the representative count. It has many additional benefits. For instance, it supports overlapping clusters in a natural way. Moreover, for every cluster, it selects a representative object, which can be effectively used in summarization or semi-supervised classification task. In this work, we propose an algorithm, SimClus, for clustering with lower bound on similarity. It achieves a O(log n) approximation bound on the number of clusters, whereas for the best previous algorithm the bound can be as poor as O(n). Experiments on real and synthetic data sets show that our algorithm produces more than 40% fewer representative objects, yet offers the same or better clustering quality. We also propose a dynamic variant of the algorithm, which can be effectively used in an on-line setting.  相似文献   
86.
Crack propagation in a series of epoxy resins described in Part 1 has been studied as a function of testing rate and temperature. It has been found that crack propagation is continuous at low temperatures but that as the temperature is raised the mode of propagation becomes unstable (stick/slip). Features on the fracture surfaces at the crack arrest lines have been shown to be of the same dimensions as those expected for a Dugdale plastic zone. It has been suggested that the slip process takes place by slow growth of a crack through the plastic zone followed by rapid propagation through virgin material. It has been shown that the stick/slip behaviour is due to blunting of the crack which is controlled by the yield behaviour of the resin. A unique fracture criterion has been shown to be applicable to epoxy resins which is that a critical stress of the order of three times the yield stress must be achieved at a critical distance ahead of the crack. Electron microscope replicas of the fracture surfaces have been obtained and an underlying nodular structure can be resolved. However, no direct correlation between the nodule size and fracture properties has been found.  相似文献   
87.
Rapid industrialization and urbanization has led to increasing input of chemical contaminants into the aquatic environment of Malaysia. Despite the threat civilization poses to the biota, there are still very few relevant studies on ecotoxicological testing of river ecosystems. To overcome this knowledge gap, we examined lethal and genotoxic effects of sediments from different rivers of the northern Malaysia against Chironomus kiiensis, a group well represented in the aquatic fauna of this region. We exposed the larvae to sediments from Selama River (SR), Permatang Rawa River (PRR) and Kilang Ubi River (KUR) at various durations (0, 6, 12, 24 and 48 h). The larval mortality was monitored, whereas DNA damage in survivors' cells was determined using the comet assay. Pollution level indexed by the amounts of heavy metals and other organic contaminants in the sediment showed progressive increases from SR to PRR to KUR. Highly polluted sediments (PRR to KUR) were detrimental to C. kiiensis larvae, most of which did not survive following exposure for long periods. DNA analyses revealed greater damages in nuclei derived from larvae maintained on polluted sediments, in particular, those from KUR. The effects on the genomic material of C. kiiensis larvae occurred in a time‐dependent manner, with damage level increasing as exposure time progressed. Our results highlight the genotoxic properties of polluted sediments. More importantly, this study showed that C. kiiensis larvae could respond to different levels of pollution with respect to exposure time. It is concluded that C. kiiensis larvae is a potential candidate for river ecotoxicological monitoring. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   
88.
Abstract

The main natural source of water available in Kuwait is the brackish groundwater located in the Kuwait Group and the Dammam aquifers, where the salinity ranges from 4300 to 10200 mg/l and from 2500 to 10000 mg/l, respectively. Limited fresh groundwater resources in Al‐Rawdhatain and Umm Al‐Aish fields, which have a salinity of 359 ‐1737 mg/l, are also available. Most of the groundwater in Kuwait is used for irrigation, domestic purposes, small‐scale industries and for blending with distilled water. Because rainfall is seasonal and less than annual evaporation, the recharge of the groundwater from rainfall is negligible. The objective of this paper is to assess the different water resources in Kuwait in order to make an integrated management plan and to focus on future sustainability. Generally, in the State of Kuwait, there is increasing pressure on the natural water resources because of the exploitation of the aquifers at a rate exceeding that of both the groundwater recharge and population growth (from 1.4 million in 1980 to 2.55 million in 2003). This has lead to the observed decline in groundwater level and to the deterioration of water quality. In the early 1950s, a plan was endorsed in Kuwait to establish seawater desalination plants. By 2005, six desalination plants have been established, with a total capacity of distillation units of 1434.72 ×103 m3/d (315.6 MIGD). However, the gross maximum consumption for the year 2003 reached a value of 1440.17 ×103 m3/d (316.8 MIGD), which is higher than the total capacity of the available distillation units. Given the limitation of conventional water and the shortages of non‐conventional water, along with the increasing population, Kuwait must consider the recycling of wastewater for irrigation, industrial or any other unrestricted non‐potable purpose.  相似文献   
89.
Indexing sequences containing multiple moving objects by all features of these objects captured at every clock tick results in huge index structures due to the large number of extracted features in all sampled instances. Thus, the main problems with current systems that index sequences containing multiple moving objects are: huge storage requirements for index structures, slow search time and low accuracy due to lack of representation of the time-varying features of objects. In this paper, a technique called cTraj to address these problems is proposed. For each object in a sequence, cTraj captures the features at sampled instances. Then, it maps the object??s features at each sampled instance from high-dimensional feature space into a point in low-dimensional distance space. The sequence of points of an object in low-dimensional space is considered the time-varying feature trajectory of the object. To reduce storage requirements of an index structure, the sequence of points in each trajectory is represented by a minimum bounding box (MBB). cTraj indexes a sequence by the MBBs of its objects using a spatial access method (SAM), such as an R?tree; thus, greatly reducing storage requirements of the index and speeding up the search time. The cTraj technique does not result in any false dismissal, but the result might contain a few false alarms, which are removed by a two-step refinement process. The experiments show that the proposed cTraj technique produces effective results comparable to those of a sequential method, however much more efficient.  相似文献   
90.
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