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排序方式: 共有1153条查询结果,搜索用时 46 毫秒
71.
Wavy roll design was employed for strengthening 1 mm thin austenitic stainless steel coil sheet by cold rolling without further reduction in thickness. This steel possesses high corrosion resistance and high ductility. Initially, the sheets were rolled into sine wave shape (wave amplitude <2 mm) and then flattened using conventional cold rolling mill. Such a process cycle was repeated for four times successfully and the mechanical properties were measured after each cycle. The yield strength increased from 255 to 931 MPa with corresponding decrease in elongation from 45% to only 17% after the fourth cycle of severe cold working. Tensile strength and hardness values increased from 753 MPa and 185 HV to 973 MPa and 371 HV, respectively. The micro-to-nano-scale resolution structures, obtained by optical and atomic force microscope (AFM), were used to explain the variation in properties during this manufacturing process and to propose schematically the deformation mechanism. 相似文献
72.
Soharab Hossain Shaikh Asis Kumar Maiti Nabendu Chaki 《Machine Vision and Applications》2013,24(2):337-350
This paper proposes a new method for image binarization that uses an iterative partitioning approach. The proposed method has been tested towards binarization of both document and graphic images. The quantitative comparisons with other standard methods reveal that the proposed approach outperforms existing widely used binarization techniques in terms of accuracy of binarization. The experimental results further establish the superiority of the proposed method, especially for degraded documents and graphic images. The proposed algorithm is suitable for a multi-core processing environment as it can be split into multiple parallel units of executions after the initial partitioning. 相似文献
73.
74.
Non-linear transient stability analysis has been performed to study the sub-synchronous whirl stability of a rigid rotor supported on two symmetric hydrodynamic bearings with rough surfaces subjected to a unidirectional constant load. A Reynolds type equation for finite hydrodynamic bearings, with different models of rough surfaces, has been solved using the stochastic finite element method. The trajectories of the journal center have been obtained by solving the equations of motion of the journal center by the fourth-order Runge-Kutta method. Results show an increase in the stability with transverse roughness and a decrease in the stability with isotropic roughness. A small improvement in stability is obtained with longitudinal roughness. 相似文献
75.
Chandra Sekhar Espenti Kummari Subba Venkata Krishna Rao Palakurthi Ramesh Akila Chandra Sekhar Kummara Madhusudana Rao 《IET nanobiotechnology / IET》2020,14(6):485
In this examination, we researched the advantages of DNA fragmentation and metallic nanoparticles well‐appointed with biomolecules. A novel interpretation of DNA damage by Silver Nano‐Clusters (AgNCs) which were developed by the utilization of green synthesis method was demonstrated. The green synthesis of AgNCs was accomplished by utilizing the leaf extract of Salacia mulbarica (SM). The preparation of SM‐AgNCs was developed by estimating surface plasmon resonance peak around 449 nm by using a UV–Visible spectrophotometer. The effect of phytochemicals in SM leaf extract on the development of stable SM‐AgNCs was confirmed by FTIR spectroscopy. The size of the fabricated SM‐AgNCs was estimated by dynamic light scattering and zeta‐sizer analysis and the morphology of the SM‐AgNCs was examined by transmission electron microscopy. The presence of clusters of Ag particles in the prepared SM‐AgNCs was recognized by energy dispersion X‐ray analysis. The results show that saponins, phytosterols, and phenolic compounds present in plant extract may play a great part in developing the SM‐AgNCs in their specialized particles. The succeeded SM‐AgNCs shows incredible anti‐bacterial action towards Escherichia coli and Bacillus subtilis. In‐light of the antibacterial study, these SM‐AgNCs were analyzed with calf thymus‐DNA and found significant damage to the strand of thymus‐DNA.Inspec keywords: visible spectra, surface plasmon resonance, transmission electron microscopy, DNA, nanofabrication, particle size, X‐ray chemical analysis, ultraviolet spectra, molecular biophysics, nanomedicine, microorganisms, nanoparticles, silver, X‐ray diffraction, antibacterial activity, Fourier transform infrared spectra, biomedical materialsOther keywords: stable SM‐AgNCs, silver nanoparticles, ct‐DNA damage, metallic nanoparticles, silver nanoclusters, Salacia mulbarica leaf extract, reactive oxygen species, DNA fragmentation, surface plasmon resonance, UV‐Visible spectrophotometer, Fourier transform infrared spectroscopy, dynamic light scattering, Zeta‐sizer analysis, transmission electron microscopy, energy dispersive X‐ray analysis, saponins, phytosterols, phenolic compounds, plant extract, Escherichia coli, Bacillus subtilis, Ag 相似文献
76.
During unidirectional micropyretic synthesis, a high-temperature reaction front propagates in a steady, oscillatory or unstable manner, depending on the reaction conditions chosen, thereby converting a reactant mix to products which display features of the wave propagation conditions. Bands are sometimes noted in the synthesized solid, often with a fixed periodicity along the propagation direction. This banded structure is thought to be the signature of an oscillating wave front. In previous articles by us and others, banded structures and other residual instabilities have been thought to arise from variations in the combustion front velocity caused by a mismatch between the heat diffusion rate and the heat production rate from the product synthesis (i.e. by exceeding the critical Lewis number). Such thermal oscillations have been modeled in the past by a single overall reaction formulation and a corresponding heat flow solution. Spiral fronts have also been noted. It is likely that the banded structures could also have originated from entropy-generating, dissipative, Belousov–Zhabotinsky (BZ) type reactions. The overall BZ reaction progresses in the form of a non-linear oscillator with several intermediary steady-state sub-reactions contained in a reaction volume. One possible sub-reaction sequence by which a BZ reaction may occur during micropyretic synthesis is discussed. Micropyretic synthesis can invoke both types of oscillations, i.e. the Lewis type and the BZ type. Two binary systems where the BZ oscillations are possible, namely the Ti–B and Ni–Al alloy systems, are examined. Spiral fronts are thought to contain both types of oscillations. A comparison with experiments shows that the micropyretic product chemistry is adequately predicted for the first time by a BZ formulation in both systems. Modeling methods for both types of oscillations are presented and integrated for the special case where an oscillation in the liquid metal concentration is noted. Forward reaction rate constants are calculated for the sub-reactions. 相似文献
77.
A. Das N. Das M.K. Naskar D. Kundu M. Chatterjee H.S. Maiti 《Ceramics International》2009,35(5):1799-1806
Silicalite-1 particles with minimum twinning have been synthesized inside the polar core of non-ionic surfactant/co-surfactant-stabilized water-in-oil (w/o) type emulsions at 150° ± 1 °C within a short reaction time of 5 h. The non-ionic surfactants of varying hydrophilic–lipophilic balance (HLB) values, i.e. sorbitan monooleate (Span 80, HLB: 4.3), sorbitan monolaurate (Span 20, HLB: 8.6), polyoxyethylene (4) lauryl ether (Brij 30, HLB: 9.7) and polyoxyethylene sorbitan monooleate (Tween 80, HLB: 15), the cationic surfactant, i.e. cetyl trimethyl ammonium bromide (CTAB), surfactant concentration, co-surfactant, synthesis temperature and time have been found to play significant role in controlling size and characteristics of Silicalite-1. It has been observed that the crystallinity and size of Silicalite-1 can be tailored by adjusting the interactions between the polar surfactant head groups at the w/o interface and the growing crystallographic surfaces (or silicate/TPA ions) in the aqueous medium of the emulsion. 相似文献
78.
Of concern in the paper is the distribution of thermal stresses in the vicinity of a penny-shaped crack in a thick elastic
plate made of a non-isotropic material. The problem pertains to the situation where the crack is opened by a prescribed normal
pressure and a prescribed heat-flux or a prescribed temperature. 相似文献
79.
The steady, two-dimensional, incompressible MHD flow past a circular cylinder with an applied magnetic field parallel to
the main flow is studied using the finite difference method. The magnetic Reynolds number is assumed to be small. Results
are presented up to the Reynolds number R=500 and interaction parameter N=1.3. As N increases suppression of the separation is observed. Drag coefficient is decreasing for the small values of N and then increasing as N increases. It is found that a smaller value of far field distance is required as N increases.
Received 6 March 2000 相似文献
80.
Santanu K. Maiti 《Transactions of the Indian Institute of Metals》2008,61(2-3):211-215
We explore a novel transport phenomenon by studying the effect of disorder on electron transport through a thin film of varying disorder strength with the distance from its surface. A simple tight-binding model is used to describe the film which is attached to two metallic electrodes, where the coupling of this film to the electrodes is treated through the use of Newns-Anderson chemisorption theory. It is found that, in the strong disorder regime the current amplitude through the film increases with the increase of the disorder strength, while it decreases in the weak disorder regime. This strange behavior is completely opposite to that of a conventional disordered system. Our results also predict that the electron transport is significantly influenced by the finite size of the thin film. 相似文献