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991.
M. Verman B. Singh J.L. Jethwa M.N. Viladkar 《International Journal of Rock Mechanics and Mining Sciences》1997,34(5):851-858
Based on the field data obtained from 12 Indian and several NGI case histories, a semi-empirical relation has been proposed in this paper for determination of “mobilised” cohesion around underground openings. It has been found that mobilisation of cohesion takes place at higher values around underground openings than the valves previously suggested and the values obtained from block shear tests. A strength enhancement factor has been suggested which is to be multiplied with the cohesion parameter obtained from block shear tests for practical application. This apparent strength enhancement may be attributed to anisotropy in strength, statistical variation in strength and confining conditions around tunnels. 相似文献
992.
993.
994.
The results of measurement of thermal expansion coefficient from 50°C to the softening temperature on eight glass compositions
of the As-Sb-Se system are presented. Measurements have been made on (As, Sb)40Se60 and As
x
Sb15Se85−x
glasses at heating rates of 1°C/min and 5°C/min. The composition and temperature dependence of the thermal expansion coefficient
is discussed in the light of results of other chalcogenide glasses. 相似文献
995.
996.
Gurdeep Singh 《Mine Water and the Environment》1986,5(1):21-32
The coal mining industry is facing serious corrosion problems. Millions of litres of water is disposed off from some underground coal mines every day. In this survey, mine water samples from various underground coal mines were collected and analysed in an attempt to correlate the various physicochemical characteristics with their corrosivity. The analyses include determination of the values of pH, alkalinity, acidity, specific conductivity, hardness, total solids, sulphate, chloride, cupric, ferrous and ferric ions. Corrosion rates of steel in minewaters were also measured by weight-loss trial method. The present survey shows that mine waters are nearly neutral, alkaline, midly acidic and highly acidic in nature. The corrosivity of these vary from mildly to extremely corrosive. An evaluation of minewaters corrosivity using Langelier Saturation Index has also been made but no definite relationship has been found between the corrosion rate and Langelier Saturation Index. A classification of the basis of corrosivity of these mine waters is also made. Causes of aggressiveness of Fe3+, Cu2+, SO4 2?, Cl? in acid mine waters have also been discussed which conclude that corrosion rates were significantly increased by Fe3+ and Cu2+ due to their reduction to Fe2+ and metallic Cu, respectively. Occurrence of these ions in acid mine waters has also been discussed. 相似文献
997.
Near-infrared (NIR) reflectance spectroscopy was evaluated as a rapid and environmentally benign technique for the simultaneous determination of macronutrients and energy in commercially available, packaged meals. Reflectance spectra (400–2498 nm) of homogenized meals were obtained with a dispersive NIR spectrometer. Protein and moisture were measured by AOAC reference methods, total fat by a semi-automated acid hydrolysis, solvent extraction, gravimetric method and total carbohydrate calculated. Energy was calculated using Atwater factors. Using multivariate analysis software, PLS models (n = 113–115 products) were developed to relate NIR spectra of homogenized meals to the corresponding reference values. The models predicted components and energy in validation samples (n = 37–38 products), overall, with r2 of above 0.96. Ratios of deviation to performance were between 3.6 and 6.6, and indicated adequacy of the models for screening, quality control, or process control. Performance of the models varied substantially when used to predict sub-groups of meals within the validation set. 相似文献
998.
In this paper, we have developed a new full-adder cell using multiplexing control input techniques (MCIT) for the sum operation and the Shannon-based technique to implement the carry. The proposed adder cell is applied to the design of several 8-bit array multipliers, namely a Braun array multiplier, a CSA multiplier, and Baugh–Wooley multipliers. The multiplier circuits are designed using DSCH2 VLSI CAD tools and their layouts are generated by Microwind 3 VLSI CAD tools. The output parameters such as propagation delay, total chip area, and power dissipation are calculated from the simulated results. We have also calculated energy per instruction (EPI), throughput, latency, signal-to-noise ratio (SNR), and the effect of temperature on the drain current by using the generated layout output parameter of a BSIM 4 advanced analyzer. The simulated results of the proposed adder-based multiplier circuit are compared with a cell multiplier that utilizes a MCIT-based adder, a cell multiplier composed of complementary pass transistor logic-based (CPL) adders and those of other published multipliers circuits. From the analysis of these simulated results, it was found that the proposed multiplier circuit gives better performance in terms of power, propagation delay, latency and throughput than other published results. 相似文献
999.
S. N. Singh R. Gandotra P. K. Singh B. C. Chakravarty 《Bulletin of Materials Science》2005,28(4):317-323
Minority carrier lifeline, τ, is one of the most important parameters which has a decisive effect on the performance of silicon
devices based on excess carriers. The value of τ is greatly affected by the presence of impurities and defects in silicon
and its value provides a fair indication of quality of the material. Photoconductivity decay (PCD) and photocurrent generation
(PCG) methods are simple and low cost methods of measurement of minority carrier lifetime in silicon wafers. However, their
application requires care. The PCD method can give quite misleading results in case of polycrystalline wafers if there exists
potential barriers at the grain boundaries which may affect majority carrier mobility significantly. PCG needs creation of
an inducedp
+-p-n
+ structure of substantially good quality that should not degrade with time. For PCG method the T measurement under vacuum
conditions provides correct and consistent results. 相似文献
1000.
Ripening affects the quality and nutritional contents of fleshy fruits. Mango, a climacteric fruit, is very susceptible to post-harvest losses, due to fast softening. In the present paper we report the effect of 1-methylcyclopropene (1-MCP) and Ethrel on antioxidant levels in mango fruit during ripening. Use of 1-MCP is applied commercially to delay ripening while Ethrel is used to accelerate ripening of climacteric fruits. 1-MCP treatment led to decreased levels of H2O2 and lipid peroxidation, concomitant with increased activities and isozymes of catalase (CAT) and superoxide dismutase (SOD), as compared to respective controls. On the other hand, Ethrel treatment led to an increase in H2O2 and lipid peroxidation, concomitant with a decrease in the activities and isozymes of catalase and SOD. Guaiacol peroxidase (GPX) could not be detected in the control or in treated fruits. Activity of ascorbate peroxidase (APX) was found to drastically increase in the presence of Ethrel while 1-MCP treatment led to only a marginal increase in APX. 相似文献