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61.
Philip Arnold Jochen Moll Moritz Mälzer Viktor Krozer Dimitry Pozdniakov Rahmi Salman Stephan Rediske Markus Scholz Herbert Friedmann Andreas Nuber 《风能》2018,21(8):676-680
This short communication reports on a radar approach for structural health monitoring of wind turbine blades. Therefore, a bistatic frequency‐modulated continuous wave (FMCW) radar in the frequency range from 33.4 to 36.0 GHz has been developed and tested experimentally using a laboratory wind turbine demonstrator. A differential damage localization framework is presented here that exploits signal differences between measurements from the intact and the damaged structure for 3D imaging of the defect. We have achieved the localization of a 30‐mm cut in a glass fiber composite structure as well as the localization of a water pack at the backside of the specimen with a localization error of several centimeters. 相似文献
62.
Deepak Rajawat Salman Siddique Sandeep Shrivastava Sandeep Chaudhary Trilok Gupta 《火与材料》2018,42(7):834-842
The residual properties of concrete subjected to elevated temperature are of importance to assess the stability of the structure. This paper investigates the performance of concrete containing white ware ceramic sand exposed to elevated temperature. Concrete mixes containing 0%, 50%, and 100% ceramic sand were prepared. The specimen were exposed to elevated temperatures of 200°C, 500°C, and 800°C for a duration of 60 minutes. Their residual mechanical properties (compressive strength, split tensile strength), ultra sonic pulse velocity, and mass change for different cooling regimes were investigated and compared among specimen. The results showed that incorporation of ceramic sand in concrete mixes improved the resistance against elevated temperature of hardened concrete. 相似文献
63.
Zia Ul-Haq Zertasha Ramzan Salman Tariq Syeda Adila Batool Muhammad Ali Javed Sami 《International journal of remote sensing》2018,39(2):544-564
This article presents a comparison analysis of OMIT (Ozone Monitoring Instrument retrieved overpass total ozone column (TOC)), and DOST (Dobson Ozone Spectrophotometer observed TOC) over Delhi during a period from October 2004 to June 2011. Megacity Delhi, located in Indo-Gangetic Basin, is an important site for comparison of ground-based and satellite retrieved TOCs due to significant anthropogenic emissions of ozone precursors, large shift in seasons, and large-scale crop residue burning in the region. DOST and OMIT data show an overall bias of 3.07% and significant correlation with coefficient of determination R2 = 0.73. Large seasonal fluctuations in the biases and correlations have been observed ranging from 2.46% (winter) to 3.82% (spring), and R2 = 0.84 (winter) to R2 = 0.09 (summer), respectively. The large biases are attributed to changes in temperature, cloud cover, pollutants emissions from urban area, and crop-residue burning events. We also find notable variations in correlations between the datasets due to the varying burden of absorbing aerosols from open field crop-residue burning. The R2 has changed from 0.67 (for aerosol optical depth, AOD 1.5–3.5) to 0.77 (for AOD 0–0.99). The dependence of the bias on solar zenith angle, cloud fraction, and satellite distance is also discussed. A simple linear regression analysis is applied to check the linkage between DOST and OMIT. The influence of atmospheric air temperature and relative humidity on OMIT at different pressure levels between 1000 and 20 hPa has been discussed. 相似文献
64.
Naveed Ahmed Madiha Rafaqat Salman Pervaiz Usama Umer Hesham Alkhalefa Muhammad Ali Shar 《Materials and Manufacturing Processes》2019,34(10):1169-1181
Nickel alloys including Inconel 718 are considered as challenging materials for machining. Laser beam machining could be a promising choice to deal with such materials for simple to complex machining features. The machining accuracy is mainly dependent on the rate of material removal per laser scan. Because of the involvement of many laser parameters and complexity of the machining mechanism it is not always simple to achieve machining with desired accuracy. Actual machining depth extremely varies from very low to aggressively high values with reference to the designed depth. Thus, a research is needed to be carried out to control the process parameters to get actual material removal rate (MRRact) equals to the theoretical material removal rate (MRRth) with minimum surface roughness (SR) of the machined surfaces. In this study, five important laser parameters have been used to investigate their effects on MRR and SR. Statistical analysis are performed to identify the significant parameters with their strength of effects. Mathematical models have been developed and validated to predict the machining responses. Optimal set of laser parameters have also been proposed and confirmed to achieve the actual MRR close to the designed MRR (MRR% = 100.1%) with minimum surface roughness (Ra = 2.67 µm). 相似文献
65.
Next‐generation optoelectronic applications such as virtual and augmented reality systems need ultrahigh resolution displays with a greater number of smaller, tightly packed pixels to avoid issues such as aliasing and the screen‐door effect. High‐resolution grid electrodes with submicron or nanoscale line widths are ideal for successful integration of more pixels with smaller light‐emitting diodes. Solution‐printed metal grid electrodes are a cost‐effective alternative to the vapor‐deposited indium tin oxide or metal grid transparent electrodes, but a scalable method to print high‐resolution (≤2 µm line width) grid structures over large flexible or rigid substrates remains elusive. A versatile, scalable, directed assembly process is presented for printing high‐resolution grid transparent conductive electrodes under ambient conditions using silver nanoparticles over large substrates. Silver grid electrodes with line widths of 2 µm and 300 nm are printed using the described process. The aspect ratio and hence the electrical properties of the transparent electrodes are tailored using the withdrawal speed and the depth of the patterned photoresist. A high‐performance grid electrode with a sheet resistance of 43 Ω sq−1 and an average transmittance of ≈93% to visible light is realized. The printed grid electrodes are also remarkably flexible and are suited to a wide variety of conventional and emerging optoelectronic applications. 相似文献
66.
Salman Majeed Muhammad Zafar Mushtaq Ahmad Omer Kilic Shazia Sultana Jamil Raza Ghulam Yaseen Hina Gul Sehrosh Mir Lubna Munazza Jabeen 《Microscopy research and technique》2020,83(7):767-777
The family Cactaceae is the diversified group of angiosperm plants whose pollen statistics has been used for taxonomic identification. In this article, we present the pollen morphology of eight species belong to seven taxonomically complex genera of Cactaceae including Astrophytum, Cylindropuntia, Echinocereus, Echinopsis, Mammillaria, Opuntia, and Thelocactus using light and scanning electron microscopy. The pollen grains were acetolyzed, measured, described, and electron photomicrographs were taken. Cactaceae can be characterized by presenting different palynomorphological features including pollen type, sculpturing, polar and equatorial diameter, aperture orientation, exine thickness, P/E ratio, and echini features. Four types of pollen shapes, that is, prolate spheroidal (three species), subprolate (two species), prolate (two species), and oblate spheroidal in Echinocereus reichenbachii were observed. The polar and equatorial diameter observed maximum in O. ficus indica 116.95 and 112.27 μm while minimum in M. compressa 38.42 and 21.05 μm. Pollen of two types, tricolpate in members of subfamily Cactioideae and pantoporate in the Opuntioideae were examined. The fertility percentage has been observed maximum in Opuntia macrocentra (83.84%) and minimum in Opuntia ficus‐indica (57.89%). Exine sculpturing showing great variations such as granulate, reticulate, granulate perforate and micro‐echinate foveolate ornamentation was examined only in Echinopsis eyriesii. A key to species, based on pollen micromorphological attributes, has been constructed for correct identification of complex cactus species. 相似文献
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70.
Salman R. Salman 《Polymer-Plastics Technology and Engineering》2013,52(1-2):115-122
Photooxidative aging of high-impact polystyrene sheets at 25°C was followed for different intervals of 25, 40, 50, 75, and 80 h. Five different types of samples were used, viz. virgin, and recycled once, twice, three, and four times. The optical properties of exposed samples exhibited changes as a result of discoloration. The transmittance and reflection deceases whereas absorbance increases with increasing recycling of high-impact polystyrene. 相似文献