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91.
Accurate node localization in wireless sensor networks (WSNs) is an essential for many networking protocols like clustering, routing, and network map building. The classical localization techniques such as multilateration and optimization‐based least square localization (OLSL) techniques estimate position of unknown node (UN) from the distance measured between all anchor nodes (ANs) and UNs. On the other hand, node localization using fixed terrestrial ANs suffers from poor localization accuracy because the ground to ground (GG) channel link is not reliable. By contrast, the mobile anchor deployed in unmanned aerial vehicle (UAV) provides high localization accuracy through reliable air to ground (AG) channel link. Still, the nonlinear distortion introduced in the wireless channel makes the distance measurement noisy. This noisy distance measurement also limits localization accuracy of classical localization techniques. Hence, the highly nonlinear artificial neural network (ANN) models such as multilayer perceptron (MLP) models can be applied effectively for node localization in UAV‐assisted WSNs. However, the MLP suffers from slow training speed, which limits its usage in real‐time applications. So, the extreme learning machine (ELM) is found to be a better alternative because it works on empirical error minimization theory, and its learning process requires only a single iteration. The detailed simulation analysis supports the proposed ELM localization scheme in terms of both localization accuracy and computational complexity. 相似文献
92.
93.
This investigation analyses the failure of left barrel used in engine of an aircraft. The barrel was subjected to detailed examination using standard non-destructive and destructive testing methods in order to identify the cause of failure of left barrel. The experimental results include fractography, chemical analysis, coating analysis and optical microstructure. The investigation concludes that failure is caused by the formation of corrosion pits which act as stress raiser and fatigue has assisted in propagation of the crack. 相似文献
94.
A comparative study based on the thermal performance of elliptical and offset-halves journal bearings has been carried out by solving energy equation while assuming Parabolic Temperature Profile Approximation across the fluid film for faster computation of temperatures. Investigation for the rise in oil film temperatures, thermal pressures, load capacity, and power loss for three commercially available grade oils have been carried out for bearing configurations under study. It has been found that the offset-halves journal bearing runs cooler when compared with elliptical journal bearing profile with minimum power loss and good load capacity using Oil 2 as lubricant for which minimum thermal degradation has been observed. 相似文献
95.
Rajesh Grover Satwinder S Marwaha John F Kennedy 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2001,76(3):251-256
The methanogenesis of black liquor from pulp and paper mill was achieved using immobilized cell technology in a laboratory‐scale two‐stage reactor system run continuously for 340 days. The optimum organic loading rate for the anaerobic treatment of black liquor was 8.0 kgm?3d?1 at which the % COD removal, biogas production and methane content were 55%, 11 dm3d?1 and 71%, respectively. Organic loading rates above 8.0 kgm?3d?1 were observed to be toxic to the methanogenic bacteria and resulted in decreased methane content, biogas and COD removal. The applicability of the system to the large‐scale processing and treatment of paper mill liquid waste is discussed. © 2001 Society of Chemical Industry 相似文献
96.
Rajesh V. Shende Daniel S. Krueger George A. Rossetti Stephen J. Lombardo 《Journal of the American Ceramic Society》2001,84(7):1648-1650
The synthesis, processing, and electrical properties of SrZrO3 and SrTiO3 materials have been examined. Phase-pure powders of SrZrO3 and SrTiO3 materials were synthesized using the Pechini method. Powder processing routes that used water and 2-propanol as carrier fluids were developed to achieve high green densities, which resulted in sintered densities of >99% of the theoretical density. The relative permittivity and average breakdown strength for carefully processed SrZrO3 were 60 and 40 V/μm; the corresponding values for SrTiO3 were 400 and 35 V/μm. The higher breakdown strengths suggest that these materials can be used in high-voltage capacitor applications. 相似文献
97.
The creation of nanoscale materials for advanced structures has led to a growing interest in the area of biomineralization. Numerous microorganisms are capable of synthesizing inorganic-based structures. For example, diatoms use amorphous silica as a structural material, bacteria synthesize magnetite (Fe3O4) particles and form silver nanoparticles, and yeast cells synthesize cadmium sulphide nanoparticles. The process of biomineralization and assembly of nanostructured inorganic components into hierarchical structures has led to the development of a variety of approaches that mimic the recognition and nucleation capabilities found in biomolecules for inorganic material synthesis. In this report, we describe the in vitro biosynthesis of silver nanoparticles using silver-binding peptides identified from a combinatorial phage display peptide library. 相似文献
98.
Silica-precipitating peptides isolated from a combinatorial phage display peptide library 总被引:2,自引:0,他引:2
Many biological organisms contain specialized structures composed of inorganic materials. Cellular processes in vivo facilitate the organized assembly of mineral building blocks into complex structures. The structural hierarchy and complexity across a range of length scales are providing new ideas and concepts for materials chemistry. Proteins that direct biomineralization can be used to control the production of nanostructured materials and facilitate the fabrication of new structures. Here, we demonstrate that some of the silica-binding peptides isolated from a combinatorial phage peptide display library can be used in precipitating silica from a solution of silicic acid. The results described in this report demonstrate that peptides displayed by phages act as templates in inorganic material synthesis and provide a means of understanding how some of the biological systems may be carrying out materials chemistry in vivo. 相似文献
99.
A suffix tree approach to anti-spam email filtering 总被引:1,自引:0,他引:1
We present an approach to email filtering based on the suffix tree data structure. A method for the scoring of emails using
the suffix tree is developed and a number of scoring and score normalisation functions are tested. Our results show that the
character level representation of emails and classes facilitated by the suffix tree can significantly improve classification
accuracy when compared with the currently popular methods, such as naive Bayes. We believe the method can be extended to the
classification of documents in other domains.
Editor: Tom Fawcett 相似文献
100.
Endometriosis is a frequent disorder that commonly presents with infertility and pelvic pain. Although the precise aetiology of endometriosis is unclear, it is generally considered to involve multiple genetic, environmental, immunological, angiogenic and endocrine processes. Genetic factors have been implicated in endometriosis but the susceptibility genes remain largely unknown. Although endometriosis is a benign disorder, recent studies of endometriosis suggest endometriosis could be viewed as a neoplastic process. Evidence to support this hypothesis includes the increased susceptibility to develop ovarian clear-cell and endometrioid cancers in the presence of endometriosis, and molecular similarities between endometriosis and cancer. In this article we discuss (i) the evidence suggesting that endometriosis might be viewed as a neoplastic process, and (ii) the implications of this hypothesis for elucidating the pathogenesis of endometriosis and developing novel methods of diagnostic classification and individualised treatments. 相似文献