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1.
Acoustic Emission (AE) signals, which are electrical version of acoustic emissions, are usually analysed using a set of signal
parameters. The major objective of signal analysis is to study the characteristics of the sources of emissions. Peak amplitude(P
a
) and rise time(R
t
) are two such parameters used for source characterization. In this paper, we theoretically investigate the efficiency ofP
a
andR
t
to classify and characterize AE sources by modelling the input stress pulse and transducer. Analytical expressions obtained
forP
a
andR
t
clearly indicate their use and efficiency for source characterization. It is believed that these results may be of use to
investigators in areas like control systems and signal processing also 相似文献
2.
Uma Maheswar Rao S. S. M. S. Abdul Majeed C. Venkataseshaiah R. Sarathi 《Bulletin of Materials Science》2002,25(6):473-475
In the present work, tracking phenomena has been studied with silicone rubber material under the a.c. and d.c. voltages following
IEC-587 standards. The surface condition of the tracked zone was analysed using wide angle X-ray diffraction (WAXD) and thermogravimetric
differential thermal analysis (TG-DTA) studies. The tracking time was different for a.c. and d.c. voltages. 相似文献
3.
Pasteurized milk (225 g) adjusted to pH 6.2 was set with 3.5 milk clotting units of chymosin (EC 3.4.23.4). The same amount of milk at pH 5.8 was set with 3.5 milk clotting units of porcine pepsin (EC 3.4.23.1). Fifteen minutes after clotting, the curd was broken, and curd and whey were separated by centrifugation at 3500 × g for 20 min. The curd (30 g) was extracted at pH 6.8 in 450 ml water or at pH 6.2 (chymosin) or 5.8 (pepsin) in 450 ml 1 M sodium chloride.Chymosin was completely released from the curd and accounted for by both methods of extraction. Pepsin was completely released and accounted for after extraction in 1 M sodium chloride at pH 5.8 but was partly inactivated during extraction at pH 6.8.Assay of curd extracts and whey by a linear agar diffusion test accounted for 102 ± 6% of the pepsin activity added to milk when the curd was extracted in 1 M sodium chloride. Extraction at pH 6.8 allowed recovery of only 63% of the activity. Chymosin recovery was 100 ± 5% by both methods of curd extraction. 相似文献
4.
The 1991 census for England and Wales provides a substantial amount of data on demography, ethnicity, housing tenure, employment status, and other social factors for geographical areas ranging in size from enumeration districts upwards. Many in the health service and in the academic community are making use of the data in the 1991 census. However, users of census data need to be aware of the problems and limitations of these data, which include the format of the data, data modification and suppression, sampling error, and underenumeration. An important innovation of the 1991 census was that the census form included a question on the postcode of respondents; this allowed the Office of Population Censuses and Surveys to produce a postcode-enumeration district look up table which overcomes many of the problems previously encountered in trying to assign postcodes to enumeration districts. The new look up table also includes the grid reference of postcodes, and this will improve the geographical referencing of census data. 相似文献
5.
Noor Zamin Khan Sayed Ali Khan Muhammad Sohail M. A. Majeed Khan Jahangeer Ahmed Li Zhan Feihong Wang Muhammad Tahir Abbas Xin Xu 《Journal of the American Ceramic Society》2021,104(9):4911-4922
The trivalent rare-earth (RE3+) doped phosphors show tremendous achievement in narrow band multicolor line emission for various applications. However, the 4f–4f absorption transition of these ions is forbidden in UV and blue light excitation. Usually, a sensitizer having spin allowed transition was used as a co-dopant to excite these ions via the energy transfer phenomenon. Another approach promisingly using to excite these ions by efficient energy transfer from the intrinsic emission of the Ca2LuTaO6 double perovskite phosphors host lattice. Phosphors of Ca2LuTaO6 with double perovskite structure were synthesized by using a high-temperature solid-state reaction method. The produced Ca2LuTaO6 double perovskite phosphors show an intrinsic broad band emission centered at 424 nm under the excitation of 313 nm UV light. The origin of this broad band blue emission was deeply investigated by using computation and experimental approaches. The trivalent activator Dy3+ and Eu3+ were doped is a single and co-dopant in the produced Ca2LuTaO6 phosphors to check their excitation in UV and near-UV spectral region. X-ray diffraction and scanning electron microscopy were used to investigate the structure and phase analysis. Various characterizations such as photoluminescence excitation, emission, and CIE chromaticity coordinates were measured which illustrate the potential of Dy3+ and Eu3+ activated Ca2LuTaO6 double perovskite phosphors for narrow band multicolor line emission for various applications. 相似文献
6.
First and second law investigations of a new solar‐assisted thermodynamic cycle for triple effect refrigeration
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This investigation is persuaded for the first and second law analyses of a new solar‐driven triple‐effect refrigeration cycle using Duratherm 600 oil (Duratherm Extended Life Fluid, NY, USA) as the heat transfer fluid is performed. The proposed cycle is an integration of ejector, absorption, and cascaded refrigeration cycles that could produce refrigeration output of different magnitude at different temperature simultaneously. Both exergy destruction and losses in each component and hence in the overall system are determined to identify the causes and locations of the thermodynamic imperfection. The effects of some influenced parameters such as hot oil outlet temperature, refrigerant turbine inlet pressure, and the evaporator temperature of ejector and cascaded refrigeration cycle have been observed on the first and second law performances. It is found that maximum irreversibility occurs in central receiver as 52.5% and the second largest irreversibility of 25% occurs in heliostat field. The second law efficiency of the solar driven triple effect refrigeration cycle is 2%, which is much lower than its first law efficiency of 11.5%. Analysis clearly shows that performance evaluation based on the first law analysis is inadequate and hence, more meaningful evaluation must be included in the second law analysis. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
7.
Mohammadreza Kosari Uzma Anjum Shibo Xi Alvin M. H. Lim Abdul Majeed Seayad Emmanuel A. J. Raj Sergey M. Kozlov Armando Borgna Hua Chun Zeng 《Advanced functional materials》2021,31(47):2102896
Beyond the catalytic activity of nanocatalysts, the support with architectural design and explicit boundary could also promote the overall performance through improving the diffusion process, highlighting additional support for the morphology-dependent activity. To delineate this, herein, a novel mazelike-reactor framework, namely multi-voids mesoporous silica sphere (MVmSiO2), is carved through a top-down approach by endowing core-shell porosity premade Stöber SiO2 spheres. The precisely-engineered MVmSiO2 with peripheral one-dimensional pores in the shell and interconnecting compartmented voids in the core region is simulated to prove combined hierarchical and structural superiority over its analogous counterparts. Supported with CuZn-based alloys, mazelike MVmSiO2 nanoreactor experimentally demonstrated its expected workability in model gas-phase CO2 hydrogenation reaction where enhanced CO2 activity, good methanol yield, and more importantly, a prolonged stable performance are realized. While tuning the nanoreactor composition besides morphology optimization could further increase the catalytic performance, it is accentuated that the morphological architecture of support further boosts the reaction performance apart from comprehensive compositional optimization. In addition to the found morphological restraints and size-confinement effects imposed by MVmSiO2, active sites of catalysts are also investigated by exploring the size difference of the confined CuZn alloy nanoparticles in CO2 hydrogenation employing both in-situ experimental characterizations and density functional theory calculations. 相似文献
8.
9.
The thermodynamic performance of an industrial waste heat recovery‐based trigeneration system is studied through energy and exergy efficiency parameters. The effects of exhaust gas inlet temperature, process heat pressure, and ambient temperature on both energy and exergy efficiencies, and electrical to thermal energy ratio of the system are investigated. The energy efficiency increases while electrical to thermal energy ratio and exergy efficiency decrease with increasing exhaust gas inlet temperature. On the other hand, with the increase in process heat pressure, energy efficiency decreases but exergy efficiency and electrical to thermal energy ratio increase. The effect of ambient temperature is also observed due to the fact that with an increase in ambient temperature, energy and exergy efficiencies, and electrical to thermal energy ratio decrease slightly. These results clearly show that performance evaluation of trigeneration system based on energy analysis is not adequate and hence more meaningful evaluation must include exergy analysis. The present analysis contributes to further information on the role of exhaust gas inlet temperature, process heat pressure, ambient temperature influence on the performance of waste heat recovery‐based trigeneration from a thermodynamic point of view. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
10.
Bulletin of Engineering Geology and the Environment - Ten potentially abrasive rock samples selected from various locations of Pakistan covering igneous, metamorphic and sedimentary rocks were... 相似文献