This paper considers the problem of simulating the humidity distributions of a grain storage system. The distributions are described by partial differential equations (PDE). It is quite difficult to obtain the humidity profiles from the PDE model. Hence, a discretization method is applied to obtain an equivalent ordinary differential equation model. However, after applying the discretization technique, the cost of solving the system increases as the size increases to a few thousands. It may be noted that after discretization, the degree of freedom of the system remain the same while the order increases. The large dynamic model is reduced using a proper orthogonal decomposition based technique and an equivalent model but of much reduced size is obtained. A controller based on optimal control theory is designed to obtain an input such that the output humidity reaches a desired profile and also its stability is analyzed. Numerical results are presented to show the validity of the reduced model and possible further extensions are identified. 相似文献
The present paper deals with two-unit warm standby models having one regular and one expert repairman. It is assumed that the expert is called only if the regular repairman is not able to complete the repairs within some tolerable (patience) time. In model 1, it is assumed that the regular repairman can always do the repairs of the unit, failed from standby state. In model 2, the regular repairman sometimes may not be able to do the repairs of the above nature within some patience time and the expert is called for in case of standby failure also.The various measures of system effectiveness are calculated using semi-Markov and regenerative processes. Based on these measures a rule is developed when the services of the expert man should be utilized profitably. 相似文献
Mg-Al layered double hydroxide decorated starch bionanocomposites (starch/layered double hydroxide) are prepared by solution intercalation method. The bionanocomposites are systematically characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and high-resolution transmission electron microscopy techniques. The thermal stability of starch is enhanced due to dispersion of layered double hydroxide within the starch matrix. The chemical resistance property of starch is improved substantially with slight sacrifice in biodegradation behavior by the delamination of layered double hydroxide in starch matrix. Herein, layered double hydroxide acts as potential laminated filler for change in structural, thermal, and chemical resistance properties of starch with little sacrifice in biodegradable behavior. 相似文献
The aim of this study was to isolate and screen bacteria from soil and effluent of electroplating industries for the synthesis of silver nanoparticles and characterize the potential isolate. Soil and effluent of electroplating industries from Mumbai were screened for bacteria capable of synthesizing silver nanoparticles. From two soils and eight effluent samples 20 bacterial isolates were obtained, of these, one was found to synthesize silver nanoparticles. Synthesis of silver nanoparticle by bacteria was confirmed by undertaking characterization studies of nanoparticles that involved spectroscopy and electron microscopic techniques. The potential bacteria was found to be Gram‐negative short rods with its biochemical test indicating Pseudomonas spp. Molecular characterization of the isolate by 16S r DNA sequencing was carried out which confirmed its relation to Pseudomonas hibiscicola ATCC 19867. Stable nanoparticles synthesized were 50 nm in size and variable shapes as seen in SEM micrographs. The XRD and FTIR confirmed the crystalline structure of nanoparticles and presence of biomolecules mainly proteins as agents for reduction and capping of nanoparticles. The study demonstrates synthesis of nanoparticles by bacteria from effluent of electroplating industry. This can be used for large scale synthesis of nanoparticles by cost effective and environmentally benign mode of synthesis.Inspec keywords: biotechnology, effluents, soil, biochemistry, scanning electron microscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, nanoparticles, electroplatingOther keywords: environmentally benign mode, large‐scale nanoparticles synthesis, proteins, biomolecules, Fourier transform infrared spectroscopy, X‐ray diffraction, SEM micrographs, pseudomonas hibiscicola ATCC 19867, 16S rDNA sequencing, molecular characterisation, biochemical test, gram‐negative short rods, potential bacteria, spectroscopy, electron microscopic techniques, soil, electroplating industries, effluent, pseudomonas spp, silver nanoparticles biosynthesis相似文献
Totally six dinuclear complexes of Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) of calix[4]arene derivatized with two pendants possessing terminal –COOH functions at two of its alternate phenolic –OH groups were synthesized for the first time and were well characterized. 相似文献
There has long been a need to experimentally measure the dynamic contact conditions of important engineering tribological systems, especially those with polymeric bearing surfaces that prove difficult to model. In order to experimentally quantify the dynamic contact conditions of geometrically complex polymeric bearing surfaces, a composite sensor material has been developed. In this study, qualitative morphological analysis of virgin ultrahigh molecular weight polyethylene (UHMWPE) and carbon black (CB) powders, as well as UHMWPE and CB powder mixtures of varying percentages was performed using field emission scanning electron microscopy (FESEM). Quantitative structure and friction analysis using atomic force microscopy (AFM) was performed on cryoultrasectioned block surfaces of compression-molded CB/UHMWPE composite. In addition, the mechanical properties of the composites were quantified using tensile testing, and the force dependence of the electrical properties was examined under dynamic compressive loading. 相似文献
In this paper, a model of two dimensional problem of generalized thermoelasticity for a fiber-reinforced anisotropic elastic medium under the effect of temperature dependent properties is established. Reflection phenomena of plane waves in an initially stressed thermoelastic medium is studied in the context of two theories proposed by Lord–Shulman and Green–Lindsay. Using proper boundary conditions, the amplitude ratios and energy ratios for various reflected waves are presented. The phase speeds, reflection coefficients and energy ratios are computed numerically with the help of MATLAB programming and are depicted graphically to show the effect of initial stress and temperature dependent properties. It is found that there is no dissipation of energy at the boundary surface during reflection. A comparison between the two theories is also depicted in the present investigation.
The present investigations are focused on the effect of different Ti-based catalysts (Ti, TiO2, TiCl3 and TiF3) on de/re-hydrogenation characteristics of nanocrystalline MgH2. Desorption temperature of milled MgH2 lowers from 380 to 350, 340, 310 and 260 °C with the addition of Ti, TiO2, TiCl3 and TiF3 respectively. The rehydrogenation characteristics are also improved through the deployment of Ti-based catalysts. Among all Ti based additives, TiF3 is found to be the most effective catalyst for hydrogen sorption from nano MgH2. The better catalytic effect of TiF3 over other Ti-based catalyst can be explained on the basis of temperature programmed reduction (TPR) studies. TPR experiments performed for different Ti additives, reveals that there is no oxidation/reduction reaction below 400 °C except for TiF3. The TPR profile of TiF3 shows some oxidation/reduction reaction exhibits at 200 °C. In order to further improve the sorption characteristics and cyclability of TiF3 catalyzed nano MgH2, we have investigated the effect of SWCNTs in MgH2+TiF3 sample. De/rehydrogenation characteristics reveal the synergistic effect of SWCNTs and TiF3 in MgH2+TiF3 sample. The details of the improvement in sorption behavior of MgH2–TiF3 in presence of SWCNTs are described and discussed. 相似文献
This paper presents the design of a cylindrical dielectric resonator antenna (DRA) using a nearly temperature stable dielectric composite material. By the combination of compounds with positive and negative temperature coefficient, a dielectric composite series (1 ? x)(Mg0.95Zn0.05)TiO3 ? x(Ca0.8Sr0.2)TiO3 has been developed. The structural and morphological properties of the grown samples have been characterized by means of X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray (EDX) spectroscopy analysis. Microwave dielectric properties of the composite samples have been investigated using the TE01δ dielectric resonator method. Relative permittivity (?r) of 21.9, dielectric loss tan δ of 0.0002 and temperature coefficient of resonant frequency (τf) of ?0.15 ppm/°C have been obtained for the x = 0.08 sample, which was used for designing the DRA. The DRA resonates at 4.6 GHz frequency and offers the bandwidth of 315 MHz. The characteristics of proposed DRA have been simulated using the Ansoft high frequency structure simulator (HFSS). Comparison between the simulated and measured results shows a reasonably good agreement. 相似文献