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排序方式: 共有406条查询结果,搜索用时 9 毫秒
31.
N. Rajagopalan P. G. Shukla C. Bhaskar V. S. Banker J. R. Dharia Kartic C. Khilar 《应用聚合物科学杂志》1992,45(5):909-913
A starch urea formaldehyde (starch-UF) matrix has been studied for application to the encapsulation of a solid insecticide. The pertinent parameters relating to the matrix synthesis have been identified and the influences of these parameters on release of the insecticide from the starch UF matrix have been investigated. The key parameter controlling the rate of release is the urea to starch ratio. It is shown that the release process can be described in terms of the generalized equation Mt/M∞ = ktn where k and n vary with system variables. 相似文献
32.
A maximum likelihood-based method is proposed for blur identification from multiple observations of a scene. When the relations among the blurring functions are known, the estimate of blur obtained using the proposed method is very good. Since direct computation of the likelihood function becomes difficult as the number of images increases, we propose an algorithm to compute the likelihood function recursively. 相似文献
33.
G Pavlinkova K Rajagopalan S Muller A Chavan G Sievert D Lou C O''Toole B Haley H Kohler 《Canadian Metallurgical Quarterly》1997,201(1):77-88
Mesophasic proliposomal system for levonorgestrel was developed and evaluated both in vitro and in vivo. The vesicles were mostly unilamellar, however, few vesicles were multilamellar which budded off spontaneously upon hydration. The release of drug from this system adhered to zero order kinetics. The effect of alcohols and volatile oils on transdermal flux was investigated. The flux was found to be the highest for alcohol, and followed by that for lemon oil. The in vivo studies indicate the requirement for a loading dose, since, a significant lag phase was observed before the therapeutic levels were reached. This system was, however, superior to the PEG-based ointment system which was employed as the control formulation. The results demonstrate the potential of proliposomal system for efficacious transdermal delivery of hydrophobic drugs. 相似文献
34.
S.S. Singh R. Sarkar H.-X. Xie C. Mayer J. Rajagopalan N. Chawla 《Journal of Electronic Materials》2014,43(4):978-982
The growth of metallic (predominantly Sn) whiskers from pure metallic platings has been studied for over 50 years. While the phenomenon of Sn whiskering has been studied for decades, very little is known about the mechanical properties of these materials. This can be attributed to the difficulty in handling, gripping, and testing such fine-diameter and high-aspect-ratio whiskers. We report on the stress–strain behavior of Sn whiskers inside a dual-beam focused ion beam (FIB) with a scanning electron microscope (SEM). Lift-out of the whiskers was conducted in situ in the FIB, and the whiskers were tested using a microelectromechanical system tensile testing stage. Using this technique, the whiskers had minimum exposure to ambient air and were not handled by hand. SEM images after fracture enabled reliable calculation of the whisker cross-sectional area. Tests on two different whiskers revealed relatively high tensile strengths of 720 MPa and 880 MPa, respectively, and a limited strain to failure of ~2% to 3%. For both whiskers, the Young’s modulus was between 42 GPa and 45 GPa. It is interesting to note that the whiskers were quite strong and had limited ductility. These findings are intriguing and provide a basis for further work to understand the effect of Sn whisker mechanical properties on short circuits in electronics. 相似文献
35.
A recently discovered clostridial bacteria converts components of synthesis gas (CO, CO2, H2) into liquid products such as ethanol, butanol and acetic acid. Isolated from an agricultural lagoon, the stability and productivity characteristics of the bacteria were studied in a continuous 4.5 l bubble column bioreactor at 37°C using artificial blends of CO, CO2, and N2. Preliminary results on the rates of cell growth, substrate utilization, product formation, and yields of products and cells from CO are discussed. At steady state, apparent yields (mole C in products per mole CO consumed) of ethanol, butanol, and acetic acid were 0.15, 0.075 and 0.025, respectively, and the cell yield was 0.25 g/mol CO. The theoretical yield of ethanol is 0.33 if CO is only utilized for the production of ethanol. The experimental yield of CO2 from CO was approximately 60% compared to the theoretical yield of 67% with ethanol as the sole product. As a comparison with another ethanol-producing bacteria, the results of a similar fermentation study using batch-grown Clostridium ljungdahlii showed yields of 0.062 for ethanol and 0.094 for acetic acid and a cell yield of 1.378 g/mol. 相似文献
36.
Effect of average flow and capacity utilization on effluent water quality from US municipal wastewater treatment facilities 总被引:1,自引:0,他引:1
There is increasing interest in decentralization of wastewater collection and treatment systems. However, there have been no systematic studies of the performance of small treatment facilities compared with larger plants. A statistical analysis of 4 years of discharge monthly report (DMR) data from 210 operating wastewater treatment facilities was conducted to determine the effect of average flow rate and capacity utilization on effluent biochemical oxygen demand (BOD), total suspended solids (TSS), ammonia, and fecal coliforms relative to permitted values. Relationships were quantified using generalized linear models (GLMs). Small facilities (40 m3/d) had violation rates greater than 10 times that of the largest facilities (400,000 m3/d) for BOD, TSS, and ammonia. For facilities with average flows less than 40,000 m3/d, increasing capacity utilization was correlated with increased effluent levels of BOD and TSS. Larger facilities tended to operate at flows closer to their design capacity while maintaining treatment suggesting greater efficiency. 相似文献
37.
J. Wei J. Barnes S. Guha L. P. Gonzalez Y. K. Yeo R. L. Hengehold G. Rajagopalan 《Journal of Electronic Materials》2011,40(2):103-108
Bulk ternary InAs1−y
P
y
polycrystals with diameters up to 50 mm were grown from a pseudobinary InP-InAs melt using the vertical Bridgman technique.
Electrical and optical properties were investigated as functions of alloy composition and sample temperature. As-grown undoped
crystals have been found to exhibit n-type conductivity irrespective of alloy composition. Though the bulk InAs1−y
P
y
substrates show high optical transmission out to long wavelengths as well as high carrier mobility, they exhibit random compositional
fluctuations across the substrate area. 相似文献
38.
Rajagopalan S. Aller J. M. Restrepo J. A. Habetler T. G. Harley R. G. 《Industry Applications, IEEE Transactions on》2006,42(6):1464-1477
There are several applications where the motor is operating in continuous nonstationary operating conditions. Actuators and servo motors in the aerospace and transportation industries are examples of this kind of operation. Detection of faults in such applications is, however, challenging because of the need for complex signal processing techniques. Two novel methods using windowed Fourier ridges and Wigner-Ville-based distributions are proposed for the detection of rotor faults in brushless dc motors operating under continuous nonstationarity. Experimental results are presented to validate the concepts and illustrate the ability of the proposed algorithms to track and identify rotor faults. The proposed algorithms are also implemented on a digital signal processor to study their usefulness for commercial implementation 相似文献
39.
The recovery of depth from defocused images involves calculating the depth of various points in a scene by modeling the effect that the focal parameters of the camera have on images acquired with a small depth of field. In the approach to depth from defocus (DFD), previous methods assume the depth to be constant over fairly large local regions and estimate the depth through inverse filtering by considering the system to be shift-invariant over those local regions. But a subimage when analyzed in isolation introduces errors in the estimate of the depth. In this paper, we propose two new approaches for estimating the depth from defocused images. The first approach proposed here models the DFD system as a block shift-variant one and incorporates the interaction of blur among neighboring subimages in an attempt to improve the estimate of the depth. The second approach looks at the depth from defocus problem in the space-frequency representation framework. In particular, the complex spectrogram and the Wigner distribution are shown to be likely candidates for recovering the depth from defocused images. The performances of the proposed methods are tested on both synthetic and real images. The proposed methods yield good results and the quality of the estimates obtained using these methods is compared with the existing method. 相似文献
40.
S. Z. Masih J. H. Shukla K. S. Rajagopalan 《Drug development and industrial pharmacy》1979,5(4):387-405
The performance of the air-jet sieve (AJS), for the particle size analysis of pharmaceutical powder, was evaluated and compared with the conventional sieve shaker (ESS). Two grades of acetaminophen (APAP) were used as test pharmaceutical powders. The particle size analysis by the AJS was simple, reproducible, efficient and accurate. The problematic powder, possessing excessive electrostatic charges and ranging in mean diameter from 17 nm to 800 nm (beyond the scope of ESS) could be evaluated accurately by AJS. The analysis time required by AJS was relatively less than that required by ESS. The accuracy of the determination by AJS was not affected by the sample size. Both the speed of rotation (vibrations and/or shaking) and the total time of sifting affected the results of the determination by ESS. The particle size value of APAP-special determined by ESS and AJS were 680.0 ± 0.14 nm and 40.0 ± 0.32 respectively, whereas the value assigned by the manufacturer was below 74 nm (-200 mesh). The precision of either method for particle size analysis of powder possessing excessive electrostatic charge was improved by the use of carbon black as an anti-static agent. 相似文献