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1.
This paper presents effect of thickness on the physical properties of thermally evaporated cadmium selenide thin films. The films of thickness 445 nm, 631 nm and 810 nm were deposited employing thermal evaporation technique on glass and ITO coated glass substrates followed by thermal annealing in air atmosphere at temperature 300 °C. The as-deposited and annealed films were subjected to the XRD, UV–Vis spectrophotometer, source meter, SEM and EDS to find the structural, optical, electrical, morphological and compositional analysis respectively. The structural analysis shows that the films have cubic phase with preferred orientation (1 1 1) and nanocrystalline nature. The structural parameters like inter-planner spacing, lattice constant, grain size, number of crystallites per unit area, internal strain, dislocation density and texture coefficient are calculated. The optical band gap is found in the range 1.69–1.84 eV and observed to decrease with thickness. The electrical resistivity is found to increase with thickness for as-deposited films and decrease for annealed films. The morphological studies show that the as-deposited and annealed films are homogeneous, smooth, fully covered and free from crystal defects like pin holes and voids. The grains in the as-deposited films are densely packed, well defined and found to be increased with thickness. 相似文献
2.
Placing a topper on a sleeping system is common practice to enhance sleeping comfort. The aim of this study was to determine the thickness and hardness effect of a mattress topper by measuring the four physiological measurements from 40 healthy males. The results showed that the use of a thin mattress topper (30 mm) significantly induced lower body pressure and temperature, higher muscle activities in the biceps femoris, and a straighter spinal alignment in the T12–L4 vertebrae. The use of a hard mattress topper significantly induced a higher body pressure, a lower body temperature in the lower extremities, a higher EMG (%MVC) in the trapezius, but a lower EMG (%MVC) in the biceps femoris, and a straighter spinal alignment at T1–T4, T4–T6, and T6–T8. Overall, a soft topper of 30-mm thickness was suggested as the best combination. The findings can provide very useful information for topper design and selection. 相似文献
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4.
Xuefu Zhang Yuanming Lai Wenbing Yu Shujuan Zhang 《Tunnelling and Underground Space Technology incorporating Trenchless Technology Research》2002,17(3)
In this paper, based on the governing differential equations of the problem of temperature field with phase change, the finite element formulae of this problem are obtained from Galerkin's method. An illustrative example of the temperature field in cold region tunnel under the conditions of the different construction seasons, different initial temperatures, different thicknesses and thermal conductivity of insulation material is provided. Then some significant results are presented, which can provide a reference for actual tunnel engineering designs in cold regions. 相似文献
5.
For multilayered plated and shell structures the formulation of the optimization problem is strongly dependant on the definition of the design variables. Therefore, the first part of the work is devoted to the definition of design variables and the forms of objective functions. Then, two numerical examples have been solved to demonstrate the effectiveness of the proposed formulations and the optimization algorithm (the modified evolutionary strategy). They deal with thickness and shape optimization problems subjected to dynamic and static constraints, respectively. 相似文献
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《Measurement》2014
Eddy current testing (ECT) is a non-destructive technique that can be used in the measurement of conductive material thickness. In this work ECT and a machine learning algorithm (support vector machine – SVM) are used to determine accurately the thickness of metallic plates. The study has been made with ECT measurements on real specimens. At a first stage, a few number of plates is considered and SVM is used for a multi-class classification of the conductive plate thicknesses within a finite number of categories. Several figures of merit were tested to investigate the features that lead to “good” separating hyperplanes. Then, based on a SVM regressor, a reliable estimation of the thickness of a large quantity of plates is tested.Eddy currents are induced by imposing a voltage step in an excitation coil (transient eddy currents – TEC), while a giant magnetoresistance (GMR) is the magnetic sensor that measures the transient magnetic field intensity in the sample vicinity. An experimental validation procedure, including machine training with linear and exponential kernels and classification errors, is presented with sets of samples with thicknesses up to 7.5 mm. 相似文献
8.
《Measurement》2014
In this paper, two silicon nitride layers with thickness, 0.2 and 0.4 μm, are coated onto single crystal silicon (SCS) in order to achieve Si3N4/Si cantilever microbeams. The effect of LPCVD silicon nitride surface coatings on fatigue properties of SCS cantilever microbeams is investigated. Fatigue testing is conducted at both 40 Hz and 100 Hz. Typical S–N (strain amplitude–fatigue cycle) curves of the beams are achieved and correlated fatigue failure modes are investigated. It is found that thinner Si3N4 coating of 0.2 μm results in better fatigue lives of Si3N4/Si beams than thicker Si3N4 coating of 0.4 μm. Both thinner and thicker coated beams have major fatigue crack planes along {1 1 1} planes; however, thicker coated beams possess specific failure mode of delamination, which is not found in thinner coated beams. Delamination reduces the reinforcing effect of thicker Si3N4 coating and leads to its shorter fatigue life. For thicker coated beams, fatigue life at 100 Hz is longer than that at 40 Hz. The mechanism for delamination and the effect of cyclic frequency is investigated, and factors for better fatigue life are proposed. 相似文献
9.
《Drug development and industrial pharmacy》2013,39(11):1354-1359
High amylose and pectin were mixed at 1:1 mass ratio and cross-linked with sodium trimetaphosphate (STMP) in alkaline medium. Films were prepared from aqueous dispersions of these cross-linked polymer blend at three different concentrations (3, 4 and 5%), by solvent casting method. Characterization of the films included thickness, surface morphology, water uptake, water vapor permeability (WVP), tensile strength measurements and enzymatic digestion. The cross-linking allowed to obtain films with improved mechanical properties and reduced WVP. The high resistance to enzymatic digestion exhibited by these films represents a promising approach to their application in the development of colon drug delivery systems. 相似文献
10.
Anh Tuan Thanh Pham Oanh Kieu Truong Le Dung Van Hoang Truong Huu Nguyen Trang Huyen Cao Pham Phuong Thanh Ngoc Vo Thang Bach Phan Vinh Cao Tran 《Journal of the European Ceramic Society》2021,41(6):3493-3500
Structure modification has been found to tune significantly the transparent-conducting performance, especially mobility and conductivity of hydrogenated Ga-doped ZnO (HGZO) films. The strong correlation between film thickness and mobility of the films is revealed. The mobility increases quickly with increasing the thickness from 350 to 900 nm, and then tends to be saturated at further thicknesses. A higher mobility than 50 cm2/Vs can be achieved, which is an extra-high value for polycrystalline ZnO films deposited by using the sputtering technique. The thickness-dependent mobility originates from scatterings on grain boundaries and dislocation-induced defects controlled by thin-film growth. Based on the Volmer-Weber model, an expansion model is built up to describe the thickness-dependent crystal growth of the HGZO films, especially at the thick films. As a result, the 800 nm-thick HGZO film obtains the highest performance with high mobility of 51.5 cm2/Vs, low resistivity of 5.3 × 10?4 Ωcm, and good transmittance of 83.3 %. 相似文献