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71.
从电子商务在我国迅速发展的角度出发,系统地介绍了我国电子商务网站的典范:阿里巴巴、淘宝。从电子商务的模式出发分析了其经营理念,成功因素及其不足,对中国的电子商务目前状况作了分析,并提出展望。 相似文献
72.
基于MATLAB语言的自动控制原理多媒体教学研究 总被引:1,自引:1,他引:0
结合我校自动化专业教学,从培养高素质,复合型人才的角度,在教学中引入目前世界上流行的MATLAB软件,并把MATLAB语言应用于经典控制系统设计和分析中,在自动控制原理多媒体辅助教学方面做了一些有益尝试和探索,取得了满意的教学效果。 相似文献
73.
《砌体工程施工质量验收规范》GB50203-2002内容简介 总被引:1,自引:0,他引:1
简要介绍国家标准《砌体工程施工质量验收规范》GB5 0 2 0 3 2 0 0 2的主要特点及内容。其中 ,着重介绍强制性条文的内容及与原相关规范、标准变更修改部分的说明 相似文献
74.
Chao-Hong Wang Sinn-Wen Chen Chia-Hua Chang Jen-Chin Wu 《Metallurgical and Materials Transactions A》2003,34(2):199-209
A series of Al-Cu-Ni alloys of various compositions were made and annealed at 800 °C. The equilibrium phases were studied
by metallography, X-ray diffraction (XRD) analysis, and electron probe microanalysis. The isothermal section of the ternary
Al-Cu-Ni system at 800 °C was then determined based on these experimental results and the available phase relationship knowledge
of the three constituent binary systems. No ternary compound was found. All three phases, AlNi3, AlNi, and Al3Ni2, have very high ternary solubility, especially the AlNi phase, which almost reaches the binary Al-Cu side. However, no continuous
solid solution was formed between the AlNi phase and any of the binary Al-Cu phases. Interfacial reactions of Al/Ni, Al/Cu,
Al-Cu/Ni, and Al-Ni/Cu at 800 °C were investigated by using reaction couple techniques. The results showed that Al3Ni and Al3Ni2 phases were formed in the Al/Ni couples; β-AlCu4, γ
1-Al4Cu9, and ɛ
2-Al2Cu3 phases were formed in the Al/Cu couples. As for the results in the Al-2 at. pct Ni/Cu, Al-5 at. pct Ni/Cu, and Al-2 at. pct
Cu/Ni, Al-4.5 at. pct Cu/Ni, and Al-6 at. pct Cu/Ni were similar to those in the binary Al/Cu and Al/Ni couples, respectively.
A different reaction path was found in the Al-7.5 at. pct Cu/Ni couples, and an AlNi solid solution layer was formed instead
of the Al3Ni and Al3Ni2 phases. 相似文献
75.
Visual tracking in high-dimensional state space by appearance-guided particle filtering 总被引:2,自引:0,他引:2
Wen-Yan Chang Chu-Song Chen Yong-Dian Jian 《IEEE transactions on image processing》2008,17(7):1154-1167
In this paper, we propose a new approach, appearance-guided particle filtering (AGPF), for high degree-of-freedom visual tracking from an image sequence. This method adopts some known attractors in the state space and integrates both appearance and motion-transition information for visual tracking. A probability propagation model based on these two types of information is derived from a Bayesian formulation, and a particle filtering framework is developed to realize it. Experimental results demonstrate that the proposed method is effective for high degree-of-freedom visual tracking problems, such as articulated hand tracking and lip-contour tracking. 相似文献
76.
Nanocomposites based on poly(butylene terephthalate) (PBT) and an organoclay (Cloisite 30B) were prepared by melt blending using a twin‐screw extruder. Two kinds of PBTs, ie PBT‐A and PBT‐B, with different inherent viscosities (ηinh), were used for this study (ηinh of PBT‐A and PBT‐B were 0.74 and 1.48, respectively). Dispersion of the clay layers in the PBT nanocomposites was characterized by using X‐ray diffraction (XRD) and transmission electron microscopy (TEM). Tensile and dynamic mechanical properties and non‐isothermal crystallization temperatures of the nanocomposites were also examined. Nanocomposites based on the higher‐viscosity PBT (PBT‐B) showed a higher degree of exfoliation of the clay and a higher reinforcing effect when compared to the composites based on the lower‐viscosity PBT (PBT‐A). The clay nanolayers dispersed in PBT matrices lead to increases in the non‐isothermal crystallization temperatures of the PBTs, with such increases being more significant for the PBT‐B nanocomposites than for the PBT‐A nanoocomposites. Copyright © 2004 Society of Chemical Industry 相似文献
77.
Poly[2‐methoxy‐5‐(2′‐ethyl‐hexyloxy)‐para‐phenylene vinylene] (MEH‐PPV)/silica nanoparticle hybrid films were prepared and characterised. Three kinds of materials were compared: parent MEH‐PPV, MEH‐PPV/silica (hybrid A films), and MEH‐PPV/coupling agent MSMA/silica (hybrid B films), in which MSMA is 3‐(trimethoxysilyl) propyl methacrylate. It was found that the hybrid B films could significantly prevent macrophase separation, as evidenced by scanning electron and fluorescence microscopy. Furthermore, the thermal characteristics of the hybrid films were largely improved in comparison with the parent MEH‐PPV. The UV‐visible absorption spectra suggested that the incorporation of MSMA‐modified silica into MEH‐PPV could confine the polymer chain between nanoparticles and thus increase the conjugation length. The photoluminescence (PL) studies also indicated enhancement of the PL intensity and quantum efficiency by incorporating just 2 wt% of MSMA‐modified silica into MEH‐PPV. However, hybrid A films did not show such enhancement of optoelectronic properties as the hybrid B films. The present study suggests the importance of the interface between the luminescent organic polymers and the inorganic silica on morphology and optoelectronic properties. Copyright © 2004 Society of Chemical Industry 相似文献
78.
Trieu-Kien Truong Yaotsu Chang Yan-Haw Chen Lee C.D. 《Communications, IEEE Transactions on》2005,53(5):749-754
In this paper, two algebraic decoders for the (103, 52, 19) and (113, 57, 15) quadratic residue codes, which have lengths greater than 100, are presented. The results have been verified by software simulation that programs in C++ language have been executed to check possible error patterns of both quadratic residue codes. 相似文献
79.
80.
Jen-Chwen Lin T. Leo Ngai Y. Austin Chang 《Metallurgical and Materials Transactions A》1986,17(7):1241-1245
Defect equilibria for binary semiconducting compound phases which exhibit ionized native donor and acceptor defects were considered,
and equations describing the pressure-temperature-composition relationships for these compound phases were derived. These
equations were used to analyze experimental data from the literature for tin telluride. Excellent agreement was obtained between
calculated thermodynamic and phase boundary values and experimental data. The approach presented is readily extended to obtain
equations for the thermodynamic properties of ternary and higher order semiconducting compound phases. 相似文献