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排序方式: 共有49条查询结果,搜索用时 31 毫秒
1.
Yi-Yu Chen 《Polymer》2007,48(18):5268-5278
A series of novel metallo-polymers containing light-emitting poly(fluorene/ethynylene/(terpyridyl)zinc(II)) backbones and electron-transporting 1,3,4-oxadiazole (OXD) pendants (attached to the C-9 position of fluorene by long alkyl spacers) were synthesized by self-assembled reactions. The integrated ratios of 1H NMR spectra reveal a facile result to distinguish the well-defined main-chain metallo-polymeric structures which were constructed by different monomer ligand systems (i.e. single, double, and triple monomer ligands with various pendants). Furthermore, UV-vis and photoluminescence (PL) spectral titration experiments were carried out to verify the metallo-polymeric structures by varying the molar ratios of zinc(II) ions to monomers. As a result, the enhancement of thermal stability (Td) and quantum yields were introduced by the metallo-polymerization, and their physical properties were mainly affected by the nature of the pendants. The photophysical properties of these metallo-polymers exhibited blue PL emissions (around 418 nm) with quantum yields of 34-53% (in DMF). In contrast to metallo-polymers containing alkyl pendants, the quantum yields were greatly enhanced by introducing 1,3,4-OXD pendants but reduced by carbazole (CAZ) pendants. Moreover, electroluminescent (EL) devices with these light-emitting metallo-polymers as emitters showed green EL emissions (around 550 nm) with turn-on voltages of 6.0-6.5 V, maximum efficiencies of 1.05-1.35 cd A−1 (at 100 mA/cm−2), and maximum luminances of 2313-3550 cd/m2 (around 15 V), respectively.  相似文献   
2.
In this paper, a new digital redesign composed of pulse width modulator (PWM) is proposed. The proposed PWM combines fuzzy logic with genetic algorithm (GA) to tune the parameter of the proposed controller such that the output response of hybrid system closely matches the one of original continuous system. Finally, an illustrated example is proposed to show the proposed method is superior to the existing one.  相似文献   
3.
Xiuzi  Wei  Zhiyang  Yi-Yu 《Computer aided design》2004,36(14):1451-1460
Today, they are students in colleges and universities. Tomorrow, they will be engineers in various industrial sectors. One of the primary goals of education is to prepare people for successful careers in the real world. As in every course, students want to obtain the maximum value of a CAD related course for their future careers. They want to obtain knowledge and skills that are most practical and useful to them when they become engineers. College professors and teachers also want to provide the maximum value for students in their CAD courses. The question is: what should be included in such a CAD curriculum. This paper tries to answer some critical questions related to developing such a curriculum, from an industrial perspective, based on the authors' survey results and the first author's own (rather limited) experiences as a R&D staff for a CAD vendor. It focuses on issues related to teaching and training students on CAD systems. These include, for different roles, how much underlying mathematical foundations in CAD systems should be taught, how much computer skills and engineering knowledge the students should know, how much design methodologies related to CAD systems should be taught, and how much ability the students should develop in order to specify their CAD needs and to evaluate and choose the CAD systems most suitable for their specific applications. The paper then shares some personal experiences and suggestions from long-term CAD veterans on the essential topics of CAD education. Based on the survey results, last section concludes the paper by authors' suggestions on what should be included in CAD curriculums for different levels of students.  相似文献   
4.
This study characterized the plasmonic scattering effects of indium nanoparticles (In NPs) on the front surface and silver nanoparticles (Ag NPs) on the rear surface of a thin silicon solar cell according to external quantum efficiency (EQE) and photovoltaic current–voltage. The EQE response indicates that, at wavelengths of 300 to 800 nm, the ratio of the number of photo-carriers collected to the number of incident photons shining on a thin Si solar cell was enhanced by the In NPs, and at wavelengths of 1,000 to 1,200 nm, by the Ag NPs. These results demonstrate the effectiveness of combining the broadband plasmonic scattering of two metals in enhancing the overall photovoltaic performance of a thin silicon solar cell. Short-circuit current was increased by 31.88% (from 2.98 to 3.93 mA) and conversion efficiency was increased by 32.72% (from 9.81% to 13.02%), compared to bare thin Si solar cells.  相似文献   
5.
基于势概率假设密度滤波的检测前跟踪新算法   总被引:2,自引:0,他引:2  
基于势概率假设密度滤波(Cardinalized Probability Hypothesis Density, CPHD)检测前跟踪(Track before detect, TBD)算法能有效解决未知目标数的弱小目标检测跟踪.文章深入研究了CPHD算法, 从标准CPHD滤波的粒子权重更新出发, 结合检测前跟踪的实际, 合理地推导出CPHD-TBD算法的粒子权重更新表达式; 分析了CPHD滤波目标势分布的物理意义, 实现了目标势分布更新计算在检测前跟踪的应用.将CPHD滤波和TBD进行有效结合, 提出了基于势概率假设密度滤波的检测前跟踪算法, 并给出其详细实现步骤.仿真实验证明提出的CPHD-TBD算法与现有概率假设密度检测前跟踪(PHD-TBD)算法相比, 能更详细地传递目标分布信息, 从本质上改变了PHD-TBD对目标数估计的方式, 能更准确稳定估计目标数, 实现了对目标的发现和状态准确估计, 性能明显更优.  相似文献   
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7.
In this work, CO2 capture was experimentally investigated by forming tetra-n-butyl ammonium bromide (TBAB) semiclathrate in a new system of TBAB + graphite nanofluids. The experiments were carried out at 3.5 MPa and 277.15 K. Compared to the TBAB solution and the TBAB + sodium dodecyl sulphate (SDS) solution, it was found that the system of TBAB + graphite nanofluids was preferable for CO2 capture, and 0.2 wt.% graphite nanoparticles (GNP) was an optimal concentration for the enhancement of hydrate growth in TBAB + graphite nanofluids. At this GNP concentration, CO2 consumption gained at 0.29 mol% TBAB is greater than that acquired at 0.62 and 2.57 mol% TBAB. CO2 consumption obtained in TBAB + graphite nanofluids is larger than other systems containing GNP. Moreover, the morphologies of TBAB + CO2 semiclathrate formed in TBAB solution, TBAB + SDS solution, and TBAB + graphite nanofluids were presented, and the mechanism of CO2 capture using TBAB semiclathrate formation in graphite nanofluids was presented. Therefore, it is an efficient way to capture CO2 by forming TBAB semiclathrate in graphite nanofluids.  相似文献   
8.
报道了液氮温度下激光束诱导电流(LBIC)和I-V测试两种在HgCdTe器件中pn结结区扩展的表征方法.通过LBIC和I-V测试,发现了p型HgCdTe材料中由B+离子注入成结和干法刻蚀成结对材料造成的损伤使得有效结区范围大于注入和刻蚀面积,并获得n区横向扩展.同时,通过对比,相互印证两种方法得到的测试结果一致.  相似文献   
9.
基于标签多伯努利滤波器的机动小目标检测前跟踪   总被引:1,自引:0,他引:1  
标签多伯努利(LMB)滤波器在传统多伯努利滤波器基础上引入标签空间,能够实现真正意义上的多目标轨迹级滤波.文章对红外小目标的运动和量测进行建模,将标签多伯努利应用到红外小目标检测前跟踪领域.在此基础上,为了实现对运动模型时变目标的检测前跟踪,将交互式多模型(IMM)与LMB检测前跟踪算法相结合,提出IMM-LMB检测前跟踪算法.此外,给出了该算法的序贯蒙特卡罗实现.仿真结果表明,所提算法能够从输入的原始图像中直接实现轨迹级多目标检测和跟踪,且能够在线更新多模型概率,更好的适应多机动目标场景.  相似文献   
10.
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