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991.
Ferhan Kayihan Orville C. Sandall Duncan A. Mellichamp 《Chemical engineering science》1977,32(7):747-754
A theoretical study of simultaneous heat and mass transfer in binary distillation has shown that heat and mass transfer coefficients can be appropriately evaluated if liquid phase temperatures and compositions are measured as functions of height in a column. In this study, the experiments were carried out in a wetted-wall column using a methanol-water binary system at one atmosphere.Special probes were designed to determine the state of the liquid phase. Temperatures were measured with microthermocouples and liquid samples were analyzed with a high precision refractometer. The liquid phase was found to be saturated which indicated, in accordance with the conclusions from a theoretical study, that all the resistance to mass transfer was in the vapor phase. Local transfer coefficients were calculated using the composition data as a function of column height. The results were correlated by an equation showing close agreement with the Chilton-Colburn equation. ?Rey?0.20 cm?1.It is concluded that mass transfer in the vapor phase is the controlling resistance in distillation and that there is no additional evaporation within the liquid phase caused by heat transferred from the vapor phase as proposed by some previous investigators. 相似文献
992.
A multiphase microscopic interference system is designed to measure the height of cell which is important to the research of collective cell migration in physiology and medicine. This sys- tem can quantitatively measure cell height across a living monolayer without knowing the refractive index of cells. For the interference pattern, because the phases are all wrapped between - π to π, it is necessary to get the real phase through phase unwrapping,a method to restore the wrapped phase data of the object by using numerical calculations. Three representative algorithms are selected to unwrap the interference pattern of ceils: branch-cut method, quality-guided method and network method. Although each of them can restore the phase, their performances are obviously different. We compare these methods and find that branch-cut method needs the smallest execution time and can obtain good unwrapped patterns when noises are not serious. 相似文献
993.
椭圆曲线密码系统是最近十几年来获得迅速发展的一类密码系统.为了提高椭圆曲线密码系统的处理速度,针对其中最关键的运算——椭圆曲线标量乘法设计并实现了一种基于FPGA的硬件结构,完成GF(2/+m)上的椭圆曲线标量乘法计算.该结构最大程度地对标量乘算法的内部模块进行了并行处理,缩短最大延迟路径,从而达到提高运算速度的目的.这一结构在FPGA上实现后,计算一次GF(2/+/{163/})上的椭圆曲线标量乘法只需要36μs,这一性能是目前国际上已知的基于FPGA的标量乘法器中最好的. 相似文献
994.
Laing S Hernandez-Santana A Sassmannshausen J Asquith DL McInnes IB Faulds K Graham D 《Analytical chemistry》2011,83(1):297-302
Tumor necrosis factor α is an inflammatory cytokine which has been linked with many infectious and inflammatory diseases. Detection and quantification of this key biomarker is commonly achieved by use of an enzyme-linked immunosorbent assay (ELISA). This fundamental technique uses the spectroscopic detection of a chromogen such as 3,3',5,5'-tetramethylbenzidine (TMB). Horseradish peroxidase (HRP), bound to the detection antibody, catalyzes the oxidation of TMB by hydrogen peroxide to generate colored products which may be measured spectrophotometrically. In this study we have used a conventional ELISA kit and shown that, by replacing the traditional colorimetric detection with resonance Raman spectroscopy, we can achieve 50 times lower detection limits and the potential for multiplexed analysis is increased. In this approach, the laser wavelength was tuned to be in resonance with an electronic transition of the oxidized TMB. The relative intensity of the enhanced Raman bands is proportional to the amount of TMB, thus providing a means of improved quantification. Furthermore, TMB is one of the most widely used chromogenic substrates for HRP-based detection and commercial ELISA test kits, indicating that this detection technique is applicable to a large number of target analytes. 相似文献
995.
An optically based rigid-body six-degrees of freedom (DOF) measurement system optimized for prospective (real-time) motion correction in magnetic resonance imaging (MRI) applications is described. By optimizing system capabilities to the specific applications requirements, the six-DOF measurement is accomplished using a single camera and simple three-disc fiducial at rates of 50 Hz. The algorithm utilizes successive approximation to solve the three point pose problem for angles close to the origin. Convergence to submicroradian levels occurs within 20 iterations for angles in an approximate half-radian (29°) arc centered on the origin. The overall absolute accuracy of the instrument is 10-100 μm for translational and <100 μrad (0.005°) for rotational motions. Results for head nodding and speech tasks are presented for subjects in the MR scanner, and the instrument results are compared to standard prospective acquisition correction. 相似文献
996.
Duncan Phillips John Taylor Rajesh Lakhanpal John Scotney Geoff Bevan 《Coloration Technology》2001,117(4):209-211
Previous studies examining the fading exhibited by optionally aftertreated acid levelling and acid milling dyes on nylon 6.6, during washing in an oxidative-bleach containing detergent, have been extended to metal complex dyes. It has been shown that, in the main, such dyes exhibit low levels of (oxidativebleach) fading in both the single cycle, stressed UK-TO (60 °C) test and after 20 machine washes at 50 °C. 相似文献
997.
Polarised attenuated total reflection (ATR) infrared spectroscopy has been used to quantify biaxial orientation in commercially manufactured poly(ethylene terephthalate) (PET) films and stretch-blow moulded bottles. Using a single-bounce accessory with a high refractive index element, and applying appropriate data normalisation prior to measuring band intensities, measurement of the average square direction cosines that describe the orientation is simple. Using this technique it was shown that uniaxially drawn PET films were actually biaxially oriented, and there were significant gradients in orientation through the film thickness. Bulk measurements, or methods that assume uniaxial orientation, would give incorrect results from these materials. The bottles exhibited complex orientation patterns that depended on preform and mould design, and again there were strong orientation gradients through the bottle walls. Kratky's model (pseudo-affine) was used in an attempt to predict the biaxial orientation gradients as a function of preform and bottle dimensions. 相似文献
998.
Thomas L. Brandon Andrew T. Rose J. Michael Duncan 《Canadian Metallurgical Quarterly》2006,132(2):250-257
The engineering behavior of low-plasticity silts is more difficult to characterize than is the behavior of clay or sand. Due to their tendency to dilate during shear, establishing a consistent and practically useful failure criterion for low-plasticity silts can be very difficult. Consideration of how the undrained shear strength of silt is related to changes in pore pressure provides a more useful and practical framework for understanding the undrained strengths of these materials and for characterizing undrained strengths for practical purposes. Using a value of Skempton’s as a failure criterion has been found to result in very reasonable values of undrained strength and to reduce scatter in the results as compared to using other criteria. Using a failure criterion based on an appropriate value of results in consistent values of Su/p, and tolerably small values of strain at failure. For low-plasticity, dilative silts that pose the greatest problems with respect to definition of “failure,” using = 0 as a failure criterion is an appropriate and simple choice. 相似文献
999.
Boccaccini Marcus T.; Murrie Daniel C.; Duncan Scott A. 《Canadian Metallurgical Quarterly》2006,18(4):415
In this study, the authors examined how overreporting of psychopathology indices on the Personality Assessment Inventory (PAI; L. C. Morey, 1991) performed as screening measures for malingering in a sample of 166 defendants undergoing pretrial court-ordered evaluations in the federal criminal justice system. Using results from the Structured Interview of Reported Symptoms (SIRS; R. Rogers, R. M. Bagby, & S. E. Dickens, 1992) as the criterion measure of malingering, the authors found that the Negative Impression scale (NIM) was the most effective PAI screening measure (cut score ≥ 81T). NIM performed as well as an established comparison measure from the Minnesota Multiphasic Personality Inventory--2 (J. N. Butcher, W. G. Dahlstrom, J. R. Graham, A. Tellegen, & B. Kaemmer, 1989; Infrequency [F] cut score ≥ 95T), supporting the use of either of these indices as reasonable screening measures to identify potential malingerers for subsequent evaluation. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
1000.
JS Duncan 《Canadian Metallurgical Quarterly》1997,244(7):403-411
Idiopathic generalized epilepsy (IGE) comprises several subsyndromes. These are principally: benign neonatal familial convulsions, benign neonatal convulsions, benign myoclonic epilepsy in infancy, childhood absence epilepsy, juvenile absence epilepsy, juvenile myoclonic epilepsy, epilepsy with generalised tonic-clonic seizures on awakening. In addition, there are less well-recognized syndromes, such as eyelid myoclonia with absences. The pathophysiology of the IGE syndromes is not fully understood; it is evident that typical absences are the result of abnormal oscillations between the thalamus and cerebral cortex. Genetic studies are in progress to elucidate the biochemical defects underlying the conditions. The clinical and electroencephalographic features of the individual subsyndromes are distinct, but some patients may be difficult to classify into a particular subgroup. A correct syndromic diagnosis is important, as treatment strategies differ for patients with the different forms of IGE, and it is necessary for genetic research. 相似文献