Crystal chemistry of alpha-quartz is discussed in relation to the nature, concentration and distribution of the common impurities. Two schemes for incorporation of impurities in the host structure,viz., the charge compensation model for untwinned natural quartz, and the broken-bond model for synthetic quartz to accomodate excess impurity residue after charge compensation, are critically reviewed. Another model for the presence of Al-H defects independent of alkali association in natural quartz is suggested. It is pointed out that the growth pressure influences the nature and distribution of impurities as well as generation of planar and line defects in synthetic quartz. It is also established that mechanicalQ (which is a measure of the acoustic loss) of synthetic crystals grown at low pressure deteriorates with increase in impurity content in excess of what is required for satisfying the charge compensation rule. 相似文献
Microsystem Technologies - This paper presents the design of a miniaturized coupled-line bandpass filter centered at 5.25 GHz with a fractional bandwidth of 20% for wireless local area... 相似文献
As part of developing a computer-aided diagnosis system for the early detection/classification of brain tumors, this paper presents an Information set-based sigmoid features and a classifier using MR images. A set of information values constituting an Information set springs forth on fitting a membership function to a set of information source (attribute) values, the sum of which gives the certainty/uncertainty in the attribute values to a class, say, the pixel intensities in an MRI to a disease class. This certainty/uncertainty representation is not attempted in the existing methods, thus failing to produce efficient features. To this end, Hanman-Anirban (HA), Mamta-Hanman (MH), and Possibilistic Renyi entropy functions are employed including the pervasive membership function in the generation of four types of sigmoid features. The pervasive Information set results from the use of pervasive membership function that is a combination of the membership function and non-membership function. Furthermore, the Shannon-Hanman Transform classifier is formulated using the t-norm of error vectors between the training and test feature vectors, and its parameters are learned through the Pervasive learning model. The proposed system comprising features, classifier, and the learning model is tested on two Brain MRI’s datasets. The t-norm based fusion of two features has also been experimented. The Shannon-Hanman Transform classifier along with the Pervasive learning model is found to outperform the other classifiers in the literature with the highest accuracy of 99.51% for the two-class classification with a fusion of two features and 99.09% for the three-class classification with a sigmoid MH feature.
In this article, we propose the use of power function and least squares method for designing of a fractional order digital differentiator. The input signal is transformed into a power function by using Taylor series expansion, and its fractional derivative is computed using the Grunwald–Letnikov (G–L) definition. Next, the fractional order digital differentiator is modelled as a finite impulse response (FIR) system that yields fractional order derivative of the G–L type for a power function. The FIR system coefficients are obtained by using the least squares method. Two examples are used to demonstrate that the fractional derivative of the digital signals is computed by using the proposed technique. The results of the third and fourth examples reveal that the proposed technique gives superior performance in comparison with the existing techniques. 相似文献
Arrays suitable for genotoxicity screening are reported that generate metabolites from cytochrome P450 enzymes (CYPs) in thin-film spots. Array spots containing DNA, various human cyt P450s, and electrochemiluminescence (ECL) generating metallopolymer [Ru(bpy)2PVP10]2+ were exposed to H2O2 to activate the enzymes. ECL from all spots was visualized simultaneously using a CCD camera. Using benzo[a]pyrene as a test substrate, enzyme activity for producing DNA damage in the arrays was found in the order CYP1B1 > CYP1A2 > CYP1A1 > CYP2E1 > myoglobin, the same as the order of their metabolic activity. Thus, these arrays estimate the relative propensity of different enzymes to produce genotoxic metabolites. This is the first demonstration of ECL arrays for high-throughput in vitro genotoxicity screening. 相似文献
A significant decrease in the degree of thermal stratification is demonstrated by improvising transverse wall ribs on the inner cylindrical surfaces of large liquid hydrogen storage tanks. The ribbed surfaces are modeled as fins and a conjugate transient heat transfer problem is formulated for predicting flow currents and heat transfer. Turbulent Rayleigh numbers between 1.2×1012 and 6×1016 are considered. A stratification parameter based on the moment of energy is defined to quantify the degree of stratification and this parameter is seen to be about 30% lower for the ribbed tanks. The degree of stratification is not sensitive to changes in the ratio of the rib height to the spacing between the ribs. The transient free convection is shown to be characterized by the parameter Fo×Ra0.15. The process of stratification takes place more slowly in the ribbed tanks than in smooth-walled tanks. The free convective heat transfer coefficient for tanks having ribbed surface is also seen to be significantly lower. Incorporation of ribs over the inner surface of the insulated tanks is demonstrated to offer a simple means of reducing the stratification and boil-off losses. 相似文献
This paper presents the theoretical investigation of CDM opportunity in a township at Jaipur, India. The purpose of study is to identify and analyze the various opportunities viz., installation of solar water heater, energy efficient lighting, energy efficient air conditioners, and energy efficient submersible water pumps in desert coolers and thus achieve a considerable (65.7?%) reduction in GHG emissions. Out of the various opportunities considered, the retrofitting with solar water heater can be recommended for CDM. Though, the retrofitting with energy efficient lighting, energy efficient air conditioners and energy efficient submersible water pumps in desert coolers claimed CO2 emission reduction of 104.84, 25.92, and 36.94?tons per annum, respectively, but the only opportunity which got through CDM was retrofitting with solar water heater claiming 115.70?tCO2 (100?%) emission reductions per annum which could result into net earnings of 115.70 CERs. The simple and discounted payback period for all four project activities are also calculated with and without CDM and tax benefits. 相似文献
Bidirectional flexure analysis of functionally graded (FG) plate integrated with piezoelectric fiber reinforced composites
(PFRC) is presented in this paper. A higher order shear and normal deformation theory (HOSNT12) is used to analyze such hybrid
or smart FG plate subjected to electromechanical loading. The displacement function of the present model is approximated as
Taylor’s series in the thickness coordinate, while the electro-static potential is approximated as layer wise linear through
the thickness of the PFRC layer. The equations of equilibrium are obtained using principle of minimum potential energy and
solution is by Navier’s technique. Elastic constants are varying exponentially along thickness (z axis) for FG material while Poisson’s ratio is kept constant. PFRC actuator attached either at top or bottom of FG plate
and analyzed under mechanical and coupled mechanical and electrical loading. Comparison of present HOSNT12 is made with exact
and finite element method (FEM). 相似文献