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排序方式: 共有155条查询结果,搜索用时 15 毫秒
1.
Influenced by partial shade, PV module aging or fault, there are multiple peaks on PV array's output power–voltage (P–V) characteristic curve. Conventional maximum power point tracking (MPPT) methods are effective for single peak P–V characteristic under uniform solar irradiation, but they may fail in global MPP tracking under multi-peak P–V characteristics. Existing methods in literature for this problem are still unsatisfactory in terms of effectiveness, complexity and speed. In this paper, we first analyze the mathematical model of PV array that is suitable for simulation of complex partial shade situation. Then an adaptive MPPT (AMPPT) method is proposed, which can find real global maximum power point (MPP) for different partial shade conditions. When output characteristic of PV array varies, AMPPT will adjust tracking strategies to search for global peak area (GPA). Then it is easy for conventional MPPT to track the global MPP in GPA. Simulation and experimental results verify that the proposed AMPPT method is able to find real global MPP accurately, quickly and smoothly for complex multi-peak P–V characteristics. Comparison analysis results demonstrate that AMPPT is more effective for most shade types. 相似文献
2.
Toward multiple maximum power point estimation of photovoltaic systems based on semiconductor theory
Jen‐Cheng Wang Yu‐Li Su Kun‐Chang Kuo Jyh‐Cherng Shieh Joe‐Air Jiang 《Progress in Photovoltaics: Research and Applications》2015,23(7):847-861
Environmental conditions, such as temperature, non‐uniform irradiation, and solar shading, deeply affect the characteristics of photovoltaic (PV) modules in PV‐assisted generation systems. Several local maximum power points (MPPs) are found in the power–voltage curve of PV systems constructed by series/parallel‐connected PV modules under partially shaded conditions. The characteristics of PV systems change unpredictably when multiple MPPs occur, so the actual MPP tracking (MPPT) becomes a difficult task. Conventional MPPT methods for the PV systems under partially shaded conditions cannot quickly find the actual MPP such that the optimal utilization of PV systems cannot be achieved. Based on the p–n junction semiconductor theory, we develop a multipoint direct‐estimation (MPDE) method to directly estimate the multiple MPPs of the PV systems under partially shaded conditions and to cope with the mentioned difficulties. Using the proposed MPDE method, the multiple MPPs of the PV systems under partially shaded conditions can be directly determined from their irradiated current–voltage and power–voltage characteristic curves. The performances of the proposed MPDE method are evaluated by examining the characteristics of multiple MPPs of PV systems with respect to different shading strengths and numbers of the shaded PV modules and also tested using the field data. The experimental results demonstrate that the proposed MPDE method can simply and accurately estimate the multiple MPPs of the PV systems under partially shaded conditions. The optimization of MPP control models and the MPPT for PV systems could be achieved promisingly by applying the proposed method. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
3.
Juan Manuel Enrique Jos Manuel Andújar Eladio Durn Miguel Angel Martínez 《Progress in Photovoltaics: Research and Applications》2015,23(12):1940-1955
This paper presents a new, simple, accurate, and inexpensive practical methodology and experimental solution for the modeling of conventional (domestic and commercial facilities) photovoltaic generators (PVG), so that they can work at their maximum power point (MPP). The PVG may be a panel, an array of panels, or a photovoltaic field. As a starting restriction (actual) it has to be assumed that it is not possible to isolate the PVG variables dependence (mainly current, voltage, and hence power) with solar radiation and temperature, because they are highly correlated. This methodology proposes the modeling facility on its MPP by its MPP resistance (RMPP = VMPP/IMPP), being VMPP and IMPP the voltage and current of the PVG, respectively, at its MPP. The analysis shows, by simulation first and then experimentally, that RMPP does not present significant temperature dependencies, at least in the usual range. This important result allows us to model the PVG only in terms of solar radiation. From a set of experimental data, different models to estimate RMPP are proposed. The obtained results are very accurate. These models allow an immediate practical application that it is also developed in the paper: MPP tracker (MPPT) design by the calculation of the DC/DC converter duty cycle which places the PVG at its MPP directly and continuously. This new methodology and experimental system has been registered in the Spanish Patent and Trademark Office with the number P201530352. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
4.
Jianliang Lin William D. Sproul John J. Moore Roman Chistyakov Bassam Abraham 《Surface & coatings technology》2011,206(7):1780
The paper presents the results on the deposition of nanoscale structurally laminated CrN films using a novel multi pulse modulated pulsed power (MPP) magnetron sputtering technique. With the multi pulse MPP approach, thin films with a structural modulation in the nanometer range are obtained by alternately switching two (or even more) high power MPP pulses on the same target, which have different pulse lengths, frequencies and powers. Each pulse was turned on for a pulse repeat duration during which this given pulse shape was repeated. In this study, CrN films have been deposited in a closed field unbalanced magnetron sputtering system using the multi pulse MPP technique by varying the pulse repeat duration of two different pulses. The CrN films were also deposited by dc magnetron sputtering (dcMS) and single pulse MPP techniques for comparison. The microstructure and properties of the films were characterized using glancing incident X-ray diffraction, scanning electron microscopy, transmission electron microscopy, nanoindentation, and ball-on-disk wear tests. The structure and properties of the multi pulse MPP CrN films depended on the pulse repeat duration. The highest hardness of 30.5 GPa and an H/E ratio of 0.9 have been achieved in the multi pulse MPP CrN films. The wear rate of the single pulse MPP and multi pulse MPP CrN films decreased by a factor of 5.8–17 as compared to the dcMS CrN films. 相似文献
5.
6.
Modulated pulse power (MPP) sputtering is a variation of high power pulsed magnetron sputtering (HPPMS) that overcomes the rate loss issue and achieves enhanced plasma ionization through modulation of the pulse shape, intensity, and duration. In this study, the principle and characteristics of MPP/HPPMS technique are first introduced. An electrostatic quadrupole plasma mass spectrometer installed parallel to the target surface has been used to examine the plasma properties, including time averaged ion energy and mass distributions of the positive ions, generated during sputtering a metal Cr target in pure Ar and Ar/N2 atmospheres using MPP and continuous dc power sources in a closed field unbalanced magnetron sputtering system. It was found that the MPP plasma exhibits a low ion energy peak at 1-2 eV and a short ion energy tail with the maximum ion energy affected by the peak current and power utilized on the cathode. A significantly increased numbers of single and double charged Cr and Ar ions were identified in the MPP plasma as compared to the dc plasma in pure Ar. The number of ions (ion flux) increased when the peak target power and current were increased. Besides single and double charged Cr, Ar and N ions, N3+, N4+, CrN+ and CrN2+ ion species were also identified in the MPP discharge with the introduction of N2 into the system. The ion energy distributions of ion species for the MPP plasma in Ar/N2 atmosphere exhibit similar peak values and tail distributions to those of the MPP plasma in pure Ar atmosphere. However, the energy tail extended toward higher energies due to the increased peak current and power on the cathode as the N2 flow rate percentage was increased in the system. 相似文献
7.
硼酸锌对MPP/PEPA阻燃PP性能的影响 总被引:1,自引:0,他引:1
采用多聚磷酸蜜胺(MPP)和笼状季戊四醇磷酸酯(PEPA)复配阻燃剂,制备了具有良好阻燃性能的无卤阻燃PP。研究了MPP/PEPA质量比和硼酸锌(ZB)用量对PP阻燃和力学性能的影响。结果表明:MPP/PEPA质量比为3∶2时,复配效果最好;添加少量的ZB即可显著提高材料的阻燃性能;当MPP/PEPA/ZB添加量分别为12%、8%和2%时,阻燃PP的氧指数高达35%,并具有较好的力学性能。TGA结果表明:添加ZB可以起催化MPP/PEPA酯化,促进成炭的作用;SEM分析表明,ZB可以起到稳定炭层,增加炭层厚度的作用。 相似文献
8.
LS MPP编程语言研究 总被引:1,自引:1,他引:0
为了方便开发运行于LS MPP系统的应用程序,文章研究了LS MPP编程语言.首先,分析了现有LS MPP计算机的体系结构,以及作为其未来发展方向的图像处理器的概念模型.然后,介绍了对应该概念模型的中间语言和中间表示.最后,详细分析了该概念模型对应的高级语言扩展部分.分析表明,高级语言对概念模型描述的并行计算机性能的提高非常有益,使程序员的编程更加方便,并且降低了编译器的复杂性. 相似文献
9.
10.
本文提出了并行求解问题时所应征用MPP系统中临界处理器数的选择方法,该方法根据问题图中每一结点的时间特征进行选择,可操作性好,易于实现,特别适用于基于互连网络的MPP系统和分布式系统。 相似文献