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排序方式: 共有594条查询结果,搜索用时 15 毫秒
41.
Scenario Management: An Interdisciplinary Approach 总被引:2,自引:0,他引:2
42.
InP MISFETs with SiO2 as the gate insulator and a deep channel recess have been fabricated. At 9 GHz the highest power output with 4 dB gain was 3.5 W/mm gate width with 33% power added efficiency. This power is more than twice that of the best GaAs MESFET. 相似文献
43.
Tien Dat Pham Kunihiko Yoshino Nga Nhu Le Dieu Tien Bui 《International journal of remote sensing》2013,34(22):7761-7788
ABSTRACTAboveground biomass (AGB) of mangrove forest plays a crucial role in global carbon cycle by reducing greenhouse gas emissions and mitigating climate change impacts. Monitoring mangrove forests biomass accurately still remains challenging compared to other forest ecosystems. We investigated the usability of machine learning techniques for the estimation of AGB of mangrove plantation at a coastal area of Hai Phong city (Vietnam). The study employed a GIS database and support vector regression (SVR) to build and verify a model of AGB, drawing upon data from a survey in 25 sampling plots and an integration of Advanced Land Observing Satellite-2 Phased Array Type L-band Synthetic Aperture Radar-2 (ALOS-2 PALSAR-2) dual-polarization horizontal transmitting and horizontal receiving (HH) and horizontal transmitting and vertical receiving (HV) and Sentinel-2A multispectral data. The performance of the model was assessed using root mean square error (RMSE), mean absolute error (MAE), coefficient of determination (R2), and leave-one-out cross-validation. Usability of the SVR model was assessed by comparing with four state-of-the-art machine learning techniques, i.e. radial basis function neural networks, multi-layer perceptron neural networks, Gaussian process, and random forest. The SVR model shows a satisfactory result (R2 = 0.596, RMSE = 0.187, MAE = 0.123) and outperforms the four machine learning models. The SVR model-estimated AGB ranged between 36.22 and 230.14 Mg ha?1 (average = 87.67 Mg ha?1). We conclude that an integration of ALOS-2 PALSAR-2 and Sentinel-2A data used with SVR model can improve the AGB accuracy estimation of mangrove plantations in tropical areas. 相似文献
44.
The finite element analysis in engineering applications comprises three phases: domain discretization, equation solving and error analysis. The domain discretization or mesh generation is the pre-processing phase which plays an important role in the achievement of accurate solutions. In this paper, the improvement of one particularly promising technique for generating two-dimensional meshes is presented. Our technique shows advantages and efficiency over some currently available mesh generators. 相似文献
45.
Corrosion properties of three different Sn‐Ag lead free solder alloys have been investigated in 0.3 wt% Na2SO4 solution as corrosive environment. As cast solder alloy was analyzed by X‐ray diffraction (XRD) and scanning electron microscopy (SEM). Volume fractions of the Ag3Sn in the solders were determined by image analysis technique. Pitting potential and corrosion potential for the alloys were determined by potentiodynamic tests. Electrochemical impedance spectroscopy (EIS) was carried out to measure the film and charge transfer resistance. Alloys with lower Ag content have been found as better corrosion resistance material. 相似文献
46.
In this paper we study how the spectral bound of Metzler operators changes under parameter perturbations. Characterizations of the stability radii of Metzler operator with respect to this type of disturbances are established. The results generalize those obtained in (Vietnam J. Math. 2006; 34 :357–368; Vietnam J. Math. 1998; 26 :147–163). Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
47.
For solving elliptic boundary value problems with singularities, we have proposed the combined methods consisting of the Ritz-Galerkin method using singular (or analytic) basic functions for one part,S 2, of the solution domainS, where there exist singular points, and the finite element method for the remaining partS 1 ofS, where the solution is smooth enough. In this paper, general approaches using additional integrals are presented to match different numerical methods along their common boundary Г0. Errors and stability analyses are provided for such a general coupling strategy. These analyses are important because they form a theoretical basis for a number of combinations between the Ritz-Galerkin and finite element methods addressed in [7], and because they can lead to new combinations of other methods, such as the combined methods of the Ritz-Galerkin and finite difference methods. Moreover, the analyses in this paper can be applied or extended to solve general elliptic boundary value problems with angular singularities, interface singularity or unbounded domain. 相似文献
48.
Kh. I. Amerkhanov I. M. Abdulagatov B. G. Alibekov G. V. Stepanov O. A. Bui 《Journal of Engineering Physics and Thermophysics》1986,51(2):957-962
Calorimeteric Cv-V-T measurements have given a new equation of state for n-propyl alcohol, which incorporates qualitative features of the critical point and the stability limit for the homogeneous phase (spinodal).Deceased.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 51, No. 2, pp. 275–281, August, 1986. 相似文献
49.
A design procedure and experimental results are presented for a class-E amplifier with an inductive impedance inverter. Experimental waveforms and characteristics measured at 1 MHz with an IRF620 MOSFET are given for the amplifier, which can operate under zero-voltage switching conditions for load resistances ranging from a short circuit to an open circuit. As the load resistance is increased at a fixed frequency, (1) the output power decreases, (2) a maximum efficiency of 96% occurs for optimum operation, (3) the peak values of the transistor voltage and the transistor current decrease, (4) the normalized peak values of the transistor voltage decrease, and (5) the normalized peak values of the transistor current increase 相似文献
50.
Nguyen Tien Phong Mohamed H. Gabr Le Hoai Anh Vu Minh Duc Andrea Betti Kazuya Okubo Bui Chuong Toru Fujii 《Journal of Materials Science》2013,48(17):6039-6047
In this study, core–shell rubber (CSR) nanoparticles with approximate particle size of 35 nm were used as a modifier for the epoxy polymer. The effects of various CSR contents in the epoxy matrix on mode I interlaminar fracture toughness, tensile strength, and fatigue life of the carbon fabric reinforced epoxy (CF/EP) composites were investigated. The experimental results showed that the mode I interlaminar fracture toughness at crack initiation and propagation significantly improved by 71.21 and 58.47 %, respectively, when 8.0 wt% CSR was dispersed in the epoxy matrix. The fatigue life of the modified CF/EP composites at all of CSR contents dramatically increased 75–100 times longer than that of the unmodified CF/EP composites at high cycle fatigue while tensile strength slightly increased by about 10 %. Field emission scanning electron microcopy (FESEM) observations of the fracture surfaces were conducted to explain failure mechanisms of CSR addition to the CF/EP composites. The evidences of the rubber nanoparticle debonding, plastic void growth, and microshear banding were credited for delaying the onset of matrix crack, and reducing the crack growth rate, as a result, attributed to increase in the mechanical properties of the CF/EP composites. 相似文献