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991.
B. K. Sarkar A. S. Verma R. C. Gupta K. Singh 《International Journal of Thermophysics》2010,31(3):620-629
Using photoacoustic spectroscopy, the composition-dependent absorption coefficient (α), thermal diffusivity (σ), and optical bandgap (E
g) of Zn1−x
Mn
x
Te diluted magnetic semiconductor have been measured. For higher Mn compositions, the absorption spectrum of the Zn–Mn–Te
system consists of three regions, viz., the high absorption region, the exponential region, and the weak absorption tail.
The bandgap follows a nonlinear variation with composition, showing a downward bowing with a minimum around x = 0.31 as a consequence of the electro-negativity difference between the substituted atoms. The composition-dependent band-edge
effective mass of the carriers does not show the bowing behavior indicating that the momentum matrix is not the same for all
the Zn1−x
Mn
x
Te alloys due to different lattice constants. The absorption spectra show that the transition is allowed and direct. 相似文献
992.
Many accounting and finance problems require ordinal multi-state classification decisions, (e.g., control risk, bond rating, financial distress, etc.), yet few decision support systems are available to aid decision makers in such tasks. In this study, we develop a Neural Network based decision support system (NN-DSS) to classify firms in four ordinal states of financial condition namely healthy, dividend reduction, debt default and bankrupt. The classification results of the NN-DSS model are compared with those of a Naïve model, a Multiple Discriminant Analysis (MDA) model, and an Ordinal Logistic Regression (OLGR) model. Four different evaluation criteria are used to compare the models, namely, simple classification accuracy, distance-weighted classification accuracy, expected cost of misclassification (ECM) and ranked probability score. Our study shows that NN-DSS models perform significantly better than the Naïve, MDA, and OLGR models on the ECM criteria, and provide better results than MDA and OLGR on other criteria, although not always significantly better. The effect of the proportion of firms of each state in the training set is also studied. A balanced training set leads to more uniform (less skewed) classification across all four states, whereas an unbalanced training set biases the classification results in favor of the state with the largest number of observations. 相似文献
993.
994.
995.
The paper decribes results of mathematical investigations into the prediction of mine water inflows to longwall coal workings. Numerical calculations are reported on the basis of experimentally deduced hydraulic conductivities above longwall panels. The effect of longwall working on hydraulic conductivities is investigated by mathematical analyses of stress and failure. Numerical calculations of mine water inflows are reported on the basis of mathematically inferred hydraulic conductivities. Results are correlated with field data. 相似文献
996.
The Laplace-Stieltjes (LS) transform for the distribution of time to first system failure (TFSF), transition probability, availability and mean time to system failure have been derived for two unit repairable redundant standby system with perfect as well as imperfect switchover condition. General expressions for computing various reliability performance indices have been obtained by using Markov Renewal techniques considering general distributions for time to failure and time to repair for the units. 相似文献
997.
K Singh 《Canadian Metallurgical Quarterly》1997,51(7):226-230
Although oxygen (O2) is needed to the body, partially reduced forms of O2 and some of their derivatives collectively called reactive oxygen species (ROS), are highly toxic prooxidants to the body. To prevent ROS toxicity body's endogenous and exogenous antioxidants (AOS) act in concert. To maintain health a balance between pro and anti oxidants is very necessary. 相似文献
998.
The numbers are staggering. In a chilling report, the U.S. Institute of Medicine (10M) estimates that somewhere between 44,000 and 98,000 Americans die each year from "avoidable medical errors" costing the nation about US$17 billion to US$29 billion annually. Errors include failing to make timely and accurate diagnosis, selecting improper treatment, and following a treatment plan incorrectly. For example, hospital staff might give the wrong drug or dosage, or a surgeon might operate on the wrong body part. Errors in surgery or emergency treatment can be especially serious. The root causes of these errors are inadequate training, poor processes, and information systems that don't expose patient information at relevant times - sometimes leading to confusion about the patient's identity or the intended procedures. Network technologies show great promise in solving some of the dangerous and tragic "avoidable medical errors" that currently plague the health care industry. 相似文献
999.
M. Deepa M. Kar D.P. Singh A.K. Srivastava Shahzada Ahmad 《Solar Energy Materials & Solar Cells》2008,92(2):170-178
Electrochemical synthesis of tungsten oxide (WO3) thin film nanostructures by potentiostatically controlling the surface aggregates formed at the electrode–electrolyte interface, in the presence of a polymeric template (polyethylene glycol 400, PEG) from a plating sol of peroxotungstic acid (PTA) is presented. The nanoparticulate morphology of the WO3 film changes drastically upon varying PEG content in the precursor sol; from an amorphous structure with randomly distributed pores for a film derived from a PTA sol with PEG:ethanol in a 3:7 volume ratio, to a mesoporous, nanocrystalline material with hybrid structures encompassing spherical grains and nanorod-like shapes with a triclinic modification for a film formed in a sol with PEG:ethanol in a 1:1 volume ratio. This approach highlights the role of the PEG proportion in controlling crystal growth, assembly patterns and pore structure. The film derived from the sol with PEG:ethanol in a 1:1 volume ratio exhibits superior transmission modulation and coloration efficiency as compared to the film obtained from a sol with PEG:ethanol in a 3:7 volume ratio. While the latter film deteriorates rapidly within 35 color-bleach cycles, the former film sustains more than 3500 cycles, without significant degradation. This film also exhibits fast switching between the clear and blue states; these are repercussions of the mesopore structure and the interconnected nanocrystallite phase. 相似文献
1000.
This paper explores the possibility of using tensile index as one of the appropriate end point parameters to determine the thermal index of a synthetic insulation paper. The paper samples were aged at three different times and temperatures. The tensile index of fresh as well as aged samples was determined experimentally. The study showed that tensile index could be considered as an appropriate parameter to find the thermal index of the chosen synthetic insulation paper. 相似文献