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排序方式: 共有3386条查询结果,搜索用时 15 毫秒
91.
El Rube I Ahmed M Kamel M 《IEEE transactions on pattern analysis and machine intelligence》2006,28(2):323-327
In this paper, new wavelet-based affine invariant functions for shape representation are presented. Unlike the previous representation functions, only the approximation coefficients are used to obtain the proposed functions. One of the derived functions is computed by applying a single wavelet transform; the other function is calculated by applying two different wavelet transforms with two different wavelet families. One drawback of the previously derived detail-based invariant representation functions is that they are sensitive to noise at the finer scale levels, which limits the number of scale levels that can be used. The experimental results in this paper demonstrate that the proposed functions are more stable and less sensitive to noise than the detail-based functions. 相似文献
92.
As a result of unmanned aerial vehicles being widely used in different areas, studies about increasing the autonomous capabilities of unmanned aerial vehicles are gaining momentum. Today, unmanned aerial vehicle platforms are especially used in reconnaissance, surveillance and communications areas. In this study, in order to achieve continuous long-range communication relay infrastructure, artificial potential field based path planning of Unmanned Aerial Vehicles is discussed. A novel dynamic approach to relay-chain concept is proposed to maintain the communication between vehicles. Besides dynamically keeping vehicles in range and appropriate position to maintain communication relay, artificial potential field based path planning also provides collision avoidance system. The performance of the proposed system is measured by applying a simulation under the Matlab Simulink and Network Simulator environment. Artificial potential field based flight patterns are generated in Matlab, and performance of the communication between vehicles is measured in Network Simulation environment. Finally the simulation results show that an airborne communication relay can be established autonomously by using artificial potential filed based autonomous path planning approach. Continues state communication is provided by obtaining a resistant communication relay which depends on artificial potential field based positioning algorithm. 相似文献
93.
Meghdad Mirabi Hamidah Ibrahim Nur Izura Udzir Ali Mamat 《Journal of Systems and Software》2012,85(8):1831-1851
In order to facilitate the XML query processing, several labeling schemes have been proposed to directly determine the structural relationships between two arbitrary XML nodes without accessing the original XML documents. However, the existing XML labeling schemes have to re-label the pre-existing nodes or re-calculate the label values when a new node is inserted into the XML document during an update process. In this paper, we devise a novel encoding scheme based on the fractional number to encode the labels of the XML nodes. Moreover, we propose a mapping method to convert our proposed fractional number based encoding scheme to bit string based encoding scheme with the intention to minimize the label size and save the storage space. By applying our proposed bit string encoding scheme to the range-based labeling scheme and the prefix labeling scheme, the process of re-labeling the pre-existing nodes can be avoided when nodes are inserted as leaf nodes and sibling nodes without affecting the order of XML nodes. In addition, we propose an algorithm to control the increment of label size when new nodes are inserted frequently at a fix place of an XML tree. Experimental results show that our proposed bit string encoding scheme provides efficient support to the process of XML updating without sacrificing the query performance when it is applied to the range-based labeling schemes. 相似文献
94.
Implementation of genetic algorithm in an embedded microcontroller-based polarization control system
Ghazaleh Mamdoohi Ahmad Fauzi Abas Khairulmizam Samsudin Noor Hisham Ibrahim Ariya Hidayat Mohd Adzir Mahdi 《Engineering Applications of Artificial Intelligence》2012,25(4):869-873
Implementation of genetic algorithm in a PIC32MX microcontroller-based polarization control system is proposed and demonstrated. The controller measures the signal intensity that is used to estimate the genetic value. This process is controlled by the genetic algorithm rather than referring to the Look-Up-Table as implemented in existing solutions. To reach optimum performance, the code is optimized by using the best genetic parameters so that the fastest execution time can be achieved. An ability of genetic algorithm to work efficiently in polarization control system possesses many advantages including easy code construction, low memory consumption and fast control speed. Genetic algorithm is intelligent enough to be used for endless polarization stabilization and in the worst case, able to stabilize the polarization changes in 300 μs. In the best case the response time can reach 17 μs. 相似文献
95.
Flavia M. S. Judice Ibrahim A. E. M. Shehata Lidia C. D. Shehata 《Materials and Structures》2006,39(3):353-364
This work investigates the horizontal and web shear resistance of continuous and discontinuous slab-web connections in pre-cast
pre-tensioned bridge systems. The beams were full scale pre-cast pre-tensioned girders and the slabs were made of ordinary
reinforced concrete either cast in place, for continuous connections, or pre-cast slabs with holes spaced at 312.5 mm to be
set in place, for discontinuous connections. The main variables were the connection type (continuous or discontinuous) and
the ratio of the connection steel.
From the test results and the numerical analysis performed, a modified stress field for the inclined compressive strut in
the truss model is proposed for continuous and discontinuous slab-web connections. The analytical results obtained with the
proposed modified stress field in the truss model compared well with the tests results. Design procedures for these types
of elements are also discussed. 相似文献
96.
ZnO/Si solar cell fabricated by spray pyrolysis technique 总被引:1,自引:0,他引:1
The ZnO/Si heterojunctions have been prepared by depositing n-ZnO films doped with aluminium on p-Si by spray pyrolysis method.
Heterojunction solar cells were fabricated using the configuration Al/ZnO/Si/In. The electrical properties of the heterojunction
are investigated by means of current–voltage measurements in the temperature range 295–375 K. The cells show the rectifying
behaviour characterized by the current–voltage (I–V) measurement under a dark condition, while photoelectric effects have
been exhibited under the illumination. As a result, the conversion efficiency of the fabricated cell of about 6.6% was obtained. 相似文献
97.
Hoh Huey Jiun Ibrahim Ahmad Azman Jalar Ghazali Omar 《Microelectronics Reliability》2006,46(5-6):836-845
This paper characterizes die damage resulting from various wafer thinning processes. Die fracture strength is measured using ball breaker test with respect to die surface finish. Further study on surface roughness and topography of each surface finish is obtained by atomic force microscopy (AFM) and scanning electron microscopy (SEM) techniques. Stress relief process with 25 μm removal is able to strengthen 100 μm wafer by 20.4% using chemical wet etch and 75 μm wafer by 36.4% with plasma etch. Relatively, plasma etching shows higher fracture strength and flexibility compared to chemical wet etch. This is due to topography of the finished surface of plasma etch is smoother and rounded, leading to a reduced stress concentration, hence improved fracture strength. 相似文献
98.
Optimization of composite plates with piezoelectric stiffener-actuators under in-plane compressive loads 总被引:1,自引:0,他引:1
Sarp Adali Ibrahim S. Sadek John C. Bruch Jr. James M. Sloss 《Composite Structures》2005,71(3-4):293-301
Stiffeners which are used to strengthen a plate can be constructed of piezoceramic materials and subsequently used as piezo actuators to improve the load carrying capacity of the plate. In the present study, a fibre composite plate with initial imperfections and under in-plane compressive loads is studied with a view towards minimizing its deflection using the piezo actuators and the fibre orientations. Piezoceramic stiffeners are bonded symmetrically on the top and bottom of the plate and deployed as actuators. Two cases of electric fields, namely, the in-phase and out-of-phase voltages are applied to the actuators. The presence of initial deflections leads to deformation under the in-plane compressive loads which should be less than the critical buckling load. Two cases of initial imperfections are considered, and the first one is the deterministic initial deflections which are known a priori and as such they are given as input parameters for the problem. In the second case the initial deflections are uncertain and they have to be obtained according to a given criterion. In the present study they are determined to produce the least favourable initial deflection (largest deflection) at a given point and the solution is obtained by convex modelling. The effect of the actuators, the ply angles and the voltage are studied and their effects on the transverse deflection are investigated. A performance index involving the L2 norm of the deflections is minimized using the piezo effect and as well as the ply angles the optimal values of which are determined for various problem parameters. 相似文献
99.
E. Subramanian G. Anitha M. Karthik Selvam M. Ibrahim Ali Badusha 《Bulletin of Materials Science》2005,28(1):55-61
An investigation on the effect ofβ-cyclodextrin (CD) in both free and inclusion-complexed forms with a guest anionic metal complex, dioxalatodiaquochromate(III)
(DDC), on the characteristics of conducting polyaniline (PANI) is carried out. Four materials, PANI (i.e. PANI-SO
4
2−
), PANI-DDC, PANI-CD and PANI-CD + DDC were prepared byin situ
chemical oxidative polymerization in aqueous H
2SO4 at pH 1 and subjected to electrical conductivity and spectral (IR and UV-vis bd measurements. DDC and CD when separately incorporated, reduce the conductivity of PANI by about half whilst their inclusion
complex CD + DDC enhances it. Spectral characterization reveals that DDC as a dopant and CD as an encapsule exhibit their
effects through adverse interaction with imine-amine N centres and benzenoid moiety of PANI. The inclusion complex CD + DDC,
on the contrary, functions as a dopant by lying in between the chains and seems to promote the extended conformation of PANI
chain and hence theπ
-electron delocalization. Exposure of the material to methanol vapour causes a decrease in conductivity in PANI and PANI-CD while an increase in PANI-CD
+ DDC. This study makes explicit the distinct role of CD as an encapsule and CD + DDC inclusion complex as a dopant in altering
the electrical property of PANI. 相似文献
100.
Analysis of Multi-Dimensional Space-Filling Curves 总被引:7,自引:0,他引:7