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141.
Abd El Rahman Shabayek Cédric Demonceaux Olivier Morel David Fofi 《Journal of Intelligent and Robotic Systems》2012,65(1-4):295-308
Unmanned aerial vehicles (UAVs) are increasingly replacing manned systems in situations that are dangerous, remote, or difficult for manned aircraft to access. Its control tasks are empowered by computer vision technology. Visual sensors are robustly used for stabilization as primary or at least secondary sensors. Hence, UAV stabilization by attitude estimation from visual sensors is a very active research area. Vision based techniques are proving their effectiveness and robustness in handling this problem. In this work a comprehensive review of UAV vision based attitude estimation approaches is covered, starting from horizon based methods and passing by vanishing points, optical flow, and stereoscopic based techniques. A novel segmentation approach for UAV attitude estimation based on polarization is proposed. Our future insightes for attitude estimation from uncalibrated catadioptric sensors are also discussed. 相似文献
142.
143.
Design patterns codify proven solutions to recurring design problems. Their proper use within a development context requires that: (i) we understand them; (ii) we ascertain their applicability or relevance to the design problem at hand; and (iii) we apply them faithfully to the problem at hand. We argue that an explicit representation of the design problem solved by a design pattern is key to supporting the three tasks in an integrated fashion. We propose a model‐driven representation of design patterns consisting of triples < MP, MS, T > where MP is a model of the problem solved by the pattern, MS is a model of the solution proposed by the pattern, and T is a model transformation of an instance of the problem into an instance of the solution. Given an object‐oriented design model, we look for model fragments that match MP (call them instances of MP), and when one is found, we apply the transformation T yielding an instance of MS. Easier said than done. Experimentation with an Eclipse Modeling Framework‐based implementation of our approach applied to a number of open‐source software application's raised fundamental questions about: (i) the nature of design patterns in general, and the ones that lend themselves to our approach, and (ii) our understanding and codification of seemingly simple design patterns. In this paper, we present the principles behind our approach, report on the results of applying the approach to the Gang of Four (GoF) design patterns, and discuss the representability of design problems solved by these patterns. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
144.
Two modified electrodes (Pb/PbO2 and C/PbO2) were prepared by electrodepositing a lead oxide layer on lead and carbon sub-strates. These modified electrodes were used as anodes for the generation of sodium hypochlorite (NaOCl) from sodium chloride solution. Different operating conditions and factors affecting the treatment process of NaOCl generation, including current density, pH values, con-ductive electrolytes, and electrolysis time, were studied and optimized. By comparison the C/PbO2 electrode shows a higher efficiency than the Pb/PbO2 electrode for the generation of NaOCl. 相似文献
145.
El‐Ghazali Talbi Matthieu Basseur Antonio J. Nebro Enrique Alba 《International Transactions in Operational Research》2012,19(1-2):283-305
In recent years, the application of metaheuristic techniques to solve multi‐objective optimization problems has become an active research area. Solving this kind of problems involves obtaining a set of Pareto‐optimal solutions in such a way that the corresponding Pareto front fulfils the requirements of convergence to the true Pareto front and uniform diversity. Most of the studies on metaheuristics for multi‐objective optimization are focused on Evolutionary Algorithms, and some of the state‐of‐the‐art techniques belong this class of algorithms. Our goal in this paper is to study open research lines related to metaheuristics but focusing on less explored areas to provide new perspectives to those researchers interested in multi‐objective optimization. In particular, we focus on non‐evolutionary metaheuristics, hybrid multi‐objective metaheuristics, parallel multi‐objective optimization and multi‐objective optimization under uncertainty. We analyze these issues and discuss open research lines. 相似文献
146.
The relationship between the stability of crack propagation in, and the fracture surface appearance of, DGEBA epoxy resins cured with TETA has been investigated using a linear elastic fracture mechanics approach. In particular, the effect of varying the amount of curing agent and curing conditions and altering external variables such as testing rate, temperature and environment have been studied. Under certain conditions, propagation is found to be stable and fracture surfaces have a smooth appearance. Under other conditions the cracks propagate in an unstable stick-slip manner. In this case, arrest lines can be seen on the fracture surfaces and their intensity and roughness increases with the magnitude of the crack jumps. The roughness of the fracture surfaces has been measured using a Talysurf and this has been shown to be due principally to deviation of the cracks from the original fracture plane rather than any gross plastic deformation. 相似文献
147.
K. C. Aw N. T. Salim W. Gao Z. Li 《Journal of Materials Science: Materials in Electronics》2006,17(8):607-614
HSG-7000 is a spin-on glass (SOG) low k dielectric material, manufactured by Hitachi Chemical and is silesquioxane (SSQ) based. The dielectric constant (k) of HSG-7000 is claimed to be 2.2. Cu diffusion through nanoporous structure of SSQ based material in Cu/Low k interconnects has been reported as a concern. Approaches to minimize Cu diffusion involve the implementation of a barrier
layer between Cu and the low k dielectric material, or surface densification via plasma treatment. This paper discusses the effects of forming gas (93%
N2 + 7% H2) plasma in an attempt to reduce Cu diffusion through the HSG-7000 film without significant increase in the dielectric constant
(k). The FTIR and XPS results suggest a formation of C–N bonds due to the plasma treatment. The depth profile measurement of
Cu using XPS confirms the reduction of Cu diffusion through the film with plasma treatment. Results show that plasma treatment
of 30–40 s on HSG-7000 will provide a reasonable Cu diffusion resistance while ensuring the increase in k is below 2.4. 相似文献
148.
In this study electrochemical performance of Al and some of its alloys (Al-Zn, Al-Mg and Al-Mn) anodes vs MnO2 cathode were carried out in alkaline solution. The results show that the Al-Zn alloy anode has the best cell capacity among the other alloys. Cell capacity values go in the order Al-Zn>Al-Mg>Al>Al-Mn. This result is probably related to the nature of passive films formed on the surface of the alloys which examined by scanning electron microscopy (SEM). SEM morphologies of Al and its alloys showed coarse grains of passive films formed on the surface of these anode materials while Al-Mn morphology shows a needle-like structure.Electrolytic manganese dioxide (EMD) produced by electrodepositing on platinum anode from liquor resulting from reduction of low grade pyrolusite ore (β-MnO2) by sulfur slag was characterized as cathode in alkaline Zn-MnO2 batteries. Ore produced sample (EMD1) was performed well in comparison with EMD standard (EMD2) (commercial battery grade electrolytic manganese dioxide, TOSOH-Hellas GH-S). SEM morphology of Zn anode after cell reaction was carried out and showed that Zn anode has fine grains of passive film on its surface. 相似文献
149.
Conventional pile materials such as steel, concrete, and timber are prone to deterioration for many reasons. Fiber-reinforced polymer (FRP) concrete composites represent an alternative construction material for deep foundations that can eliminate many of the performance disadvantages of traditional piling materials. However, FRP composites present several difficulties related to constructability, and the lack of design tools for their implementation as a foundation element. This paper describes the results of an experimental study on frictional FRP/dense sand interface characteristics and the constructability of FRP–concrete composite piles. An innovative toe driving technique is developed to install the empty FRP shells in the soil and self-consolidating concrete is subsequently cast in them. The experimental program involves interface shear tests on small FRP samples and uplift load tests on large-scale model piles. Two different FRP pile materials with different roughness and a reference steel pile are examined. Static uplift load tests are conducted on different piles installed in soil samples subjected to different confining pressures in the pressure chamber. The results showed that the interface friction for FRP materials compared favorably with conventional steel material. It was shown that toe driving is suitable for installation of FRP piles in dense soils. 相似文献
150.
Masaki Oono El‐Sayed Atlam Masao Fuketa Kazuhiro Morita Jun‐ichi Aoe 《Software》2003,33(13):1229-1249
A double‐array is a well‐known data structure to implement the trie. However, the space efficiency of the double‐array degrades with the number of key deletions because the double‐array keeps empty elements produced by the key deletion. This paper presents a fast and compact elimination method of empty elements using properties of the trie nodes that have no siblings. The present elimination method is implemented by C language. From simulation results for large sets of keys, the present elimination method is about 30–330 times faster than the conventional elimination method and maintains high space efficiency. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献