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排序方式: 共有126条查询结果,搜索用时 15 毫秒
1.
人们在频繁使用存储设备的时候,数据丢失的现象时有发生。该文主要介绍数据丢失的原因,数据丢失的处理以及如何利用软件手段来恢复PC硬盘或U盘的数据。 相似文献
2.
Heterostructured dysprosium vanadate – ZnO for photo-electrocatalytic and self-cleaning applications
In this article, we report fabrication of 5 wt% of Dy as DyVO4 supported ZnO by template-free hydrothermal-thermal decomposition method and its photocatalytic activity towards degradation of azo dyes Rhodamine-B (Rh-B) and Trypan Blue (TB) in solar light, Electrocatalytic activity in methanol oxidation and Self-cleaning properties. The as prepared DyVO4-ZnO was characterized by surface analytical and spectroscopic techniques. The results suggested that Dysprosium vanadate doping on ZnO has increased its photocatalytic efficiency with high reusability. DyVO4-ZnO exhibits higher electrocatalytic activity than prepared ZnO for methanol electrooxidation in alkaline medium, revealing its promising potential as the anode in direct methanol fuel cells. Hydrophobicity of ZnO increases by doping of DyVO4. 相似文献
3.
《Measurement》2014
In practical engineering applications, useful information is often submerged in strong noise and the feature information is difficult to be extracted. Aimed at the detection problem of multi-frequency signal under colored noise background, a novel weak signal detection method based on stochastic resonance (SR) tuning by multi-scale noise is proposed. Firstly, noisy signal is processed by orthogonal wavelet transform to decompose the signal into multi-scale ingredients. According to the orthogonal wavelet transform coefficients characteristics of 1/f distribution, multi-scale noise is constructed so as to make the frequency-band containing the driving frequency be enhanced through SR system. Thus multi-frequency weak signal is detected. The method is effective to detect multi-frequency weak signal under colored noise background. Experiment signal analysis results show that the proposed method is simple for multi-frequency weak signal detection, and has good prospects for engineering applications. 相似文献
4.
A number of microstrip antenna arrays have been designed based on the improved size patch elements with different substrate heights to evaluate the gain enhancement in practical measurements. Initially, microstrip patch antenna arrays (MPAAs) have been designed, analysed and tested at 10 GHz frequency and then the optimised high gain (∼21 dBi) array is fabricated and tested at 60 GHz-band frequencies. It has been found that the loss emergence due to the long feeding transmission line (TL) network severely degrades the antenna gain in large MPAAs on the thicker substrates. However, the gain can be significantly enhanced in large MPAAs by employing relatively thinner substrate but it shrinks the return loss (S11) bandwidth (BW) and increases the side lob level (SLL). 相似文献
5.
The radiation characteristics of the double dielectric grating leaky-wave antenna are analyzed by the improved perturbation method. The results indicate that under the condition of the same radiation intensity, the double dielectric grating antenna has relatively smaller dimensions than that of the single one. It is undoubtly of great importance in the case that the limitation of the weight and volume of system is strictly required. The results obtained from this paper are compared with the exact solution based on the mode matching method. It is justified that the present perturbation procedure yields as highly results as the rigorous approach with extremely simplicity of the analysis and calculations. 相似文献
6.
文章通过对AutoCAD矢量图转换Photoshop图片几种常用方法的探讨和比较。为工程设计人员在设计制图过程中采用最有效的方法提供了参考。 相似文献
7.
Xu Shanjia 《Journal of Infrared, Millimeter and Terahertz Waves》1987,8(9):987-999
The coupling of surface waves by two crossed dielectric slab sections with curved transition waveguides is investigated by the method of staircase approximation. the coupling problem of the nonuniform structure is analyzed in terms of the scattering of incident surface wave by the crossed structure as a whole. The scattering characteristics of the crossed waveguides are calculated with a particular attention directed to the effect of radiation due to bending of the curved transition waveguides on coupling properties of the structure. Some useful guidelines for the design of the coupling structures are thereby suggested. 相似文献
8.
9.
Weihai Fang Shanjia Xu Feng Nian Li Zhang 《Journal of Infrared, Millimeter and Terahertz Waves》2010,31(5):629-640
Scattering characteristics of strip grating sandwiched between two dielectric layers in the case of plane-wave arbitrary oblique
incidence are carefully investigated by a new method which combines coordinate revolving theory with the rigorous mode matching
method. Comparisons between the results obtained with the present method and those given by the other methods verify the effectivity
and practicability of the present method. The spatial filter characteristics of the new strip grating structure are given.
It shows that the ultra-wideband bandpass characteristics can be realized using the present structure. Besides, a new circular
polarizer is proposed. It is indicated that the new circular polarizer can realize complete circular polarization for every
frequencies by means of changing the structure parameters of the dielectric uniform layers, which overstep the limitation
of single strip that can achieve circular polarization only in a fixed frequency. The present investigation gives some useful
guidelines for accurate design of the spatial bandpass filters and circular polarizers. 相似文献
10.
高永琴 《安徽水利水电职业技术学院学报》2010,10(1):91-93
文章分析了安徽省部分高职院校一般学生长跑运动存在的主要问题是:多数学生进行长跑运动存在盲目性,缺乏科学合理的锻炼方法和正确的运动技术,这对身体健康和运动水平的提高不利。提出了解决对策:加强技术教学的同时注意长跑运动理论知识的渗入与普及。 相似文献