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121.
Reza Akhtar 《K-Theory》2004,32(3):269-291
Let k be a field and X a smooth projective variety of dimension d over k. Generalizing a construction of Kato and Somekawa, we define a Milnor-type group
which is isomorphic to the ordinary Milnor
We prove that
is isomorphic to both the higher Chow group CHd+s (X,s) and the Zariski cohomology group
相似文献
122.
Saeed‐ur‐Rehman Muhammad Arshad Masood Ahmad Khalid Masud Abdul Ghani Nasima Arshad Ammad Hussain Qureshi Sohail Akhtar Ghauri 《中国化学会会志》2000,47(3):501-508
Some of the bis‐complexes of a derivative of phenhomazine (dibenzo[b,f][1:5]diazocine‐6:12‐dione; PHZD) with Ni(II), Cu(II), Co(II), Cd(II), Zn(II) and Hg(II) of the general formula M(PHZD)2X2 [where X = C1, Br and I], were prepared and identified. These complexes have been characterised on the basis of elemental analysis, and spectroscopic, magnetic and conductance data. The thermal mode of decomposition and thermal stability of these complexes was investigated on the basis of the respective thermal curves in a static air atmosphere. The thermoanalytical investigations indicate that these complexes undergo two‐step changes as temperature is raised, except for Cd(II) and Hg(II) complexes, with the formation of metal oxides as end product. The degradation mechanism of the complexes has also been proposed. 相似文献
123.
Mohammad Arafat Hussain Farzana Alam Sharmin Akhtar Rupa Rayhana Awwal Soo Yeol Lee Md. Kamrul Hasan 《Ultrasonics》2014
Elasticity imaging techniques with built-in or regularization-based smoothing feature for ensuring strain continuity are not intelligent enough to prevent distortion or lesion edge blurring while smoothing. This paper proposes a novel approach with built-in lesion edge preservation technique for high quality direct average strain imaging. An edge detection scheme, typically used in diffusion filtering is modified here for lesion edge detection. Based on the extracted edge information, lesion edges are preserved by modifying the strain determining cost function in the direct-average-strain-estimation (DASE) method. The proposed algorithm demonstrates approximately 3.42–4.25 dB improvement in terms of edge-mean-square-error (EMSE) than the other reported regularized or average strain estimation techniques in finite-element-modeling (FEM) simulation with almost no sacrifice in elastographic-signal-to-noise-ratio (SNRe) and elastographic-contrast-to-noise-ratio (CNRe) metrics. The efficacy of the proposed algorithm is also tested for the experimental phantom data and in vivo breast data. The results reveal that the proposed method can generate a high quality strain image delineating the lesion edge more clearly than the other reported strain estimation techniques that have been designed to ensure strain continuity. The computational cost, however, is little higher for the proposed method than the simpler DASE and considerably higher than that of the 2D analytic minimization (AM2D) method. 相似文献
124.
This paper analyses declaration and the follow-on decisions in test cricket. We model the match outcome given the end of first, second and third innings positions; data on 391 test matches, from the period 1997 to 2007, are used to fit the models. We then investigate how declaration strategy should vary from innings to innings, and how the nature and strength of the covariate effects vary. As the match progresses, the explanatory power of the covariates increases (from 44% at the end of the first innings to 80% at the end of the third). Home advantage and the effects of team strengths decrease. Overs-remaining, or equivalently overs used, and the number of runs by which the reference team lead their opponents remain important throughout. The follow-on decision problem is also briefly considered, and surprisingly, we find that the decision to enforce the follow-on or otherwise has no effect on match outcome. 相似文献
125.
Imran Akhtar Rajat Mittal George V. Lauder Elliot Drucker 《Theoretical and Computational Fluid Dynamics》2007,21(3):155-170
Numerical simulations have been used to analyze the effect that vortices, shed from one flapping foil, have on the thrust
of another flapping foil placed directly downstream. The simulations attempt to model the dorsal–tail fin interaction observed
in a swimming bluegill sunfish. The simulations have been carried out using a Cartesian grid method that allows us to simulate
flows with complex moving boundaries on stationary Cartesian grids. The simulations indicate that vortex shedding from the
upstream (dorsal) fin is indeed capable of increasing the thrust of the downstream (tail) fin significantly. Vortex structures
shed by the upstream dorsal fin increase the effective angle-of-attack of the flow seen by the tail fin and initiate the formation
of a strong leading edge stall vortex on the downstream fin. This stall vortex convects down the surface of the tail and the
low pressure associated with this vortex increases the thrust on the downstream tail fin. However, this thrust augmentation
is found to be quite sensitive to the phase relationship between the two flapping fins. The numerical simulations allows us
to examine in detail, the underlying physical mechanism for this thrust augmentation.
相似文献
126.
A series of experiments has been conducted on oxygen free high conductivity (OFHC) copper hollow cylinders under cyclic free-end torsion and biaxial tension–torsion at large strains. In addition, equations are developed to account for the finite rotation and strains in electrical resistance strain gages. In free-end cyclic torsion experiments with shear strain range equal to 23%, a significant strain in the axial direction is observed and it accumulates with a constant rate cycle by cycle. In the biaxial tension–torsion (multiaxial ratchetting) experiments, in which the primary (constant) axial stress is larger than the initial yield stress of the material, the loading conditions are varied to determine the influence of primary axial stress, cyclic shear strain range, pre-cyclic hardening and loading sequence on multiaxial ratchetting. Some important experimental features are high-lighted and recommended to help modeling efforts later. 相似文献
127.
Okadaic acid (OA), a lipophilic phycotoxin highly toxic to humans is produced by toxigenic dinoflagellates. The need to develop high performing methods for OA analysis able to improve the traditional ones is evident. In this work, competitive indirect enzyme-linked electrochemical immunosensor based on super paramagnetic nanobeads has been developed for the detection of OA. Streptavidin-coated magnetic beads were used as support to immobilize the biotinylated OA. Preliminary, colorimetric tests were performed in order to optimize different experimental parameters. Electrochemical detection was carried out by differential pulse voltammetry (DPV). The limit of detection (LOD) (0.38 μg L−1), the mid point value (IC50) (3.15 μg L−1) and the time needed (60 min) for analysis of a real sample validated the developed electrochemical immunosensor as a promising tool for routine use. The matrix effect and the recovery rate were also assessed, showing an excellent percentage of recovery. 相似文献
128.
Mohamad Ridzwan Ishak Zulkiflle Leman Mohd Sapuan Salit Mohd Zaki Abd Rahman Mohd Khairun Anwar Uyup Riaz Akhtar 《Journal of Thermal Analysis and Calorimetry》2013,111(2):1375-1383
This study aimed to investigate the effect of resin impregnation on the interfacial shear strength (IFSS), thermogravimetric (TG) and fourier transform infrared (FT-IR) of sugar palm (Arenga pinnata) fibres. In addition, the effect of resin impregnation on the mechanical properties of sugar palm fibre reinforced unsaturated polyester (UP) composites was also studied. The fibres were impregnated with UP via vacuum resin impregnation process at a pressure of 600 mmHg for 5 min. Composites of 10, 20, 30, 40 and 50 % fibre loadings were fabricated and tested for tensile and flexural properties. It was observed that the impregnation process caused the fibres to be enclosed by UP resin and this gave a strong influence to the increase of its interfacial bonding by the increase of its IFSS from single fibre pull-out test. It was also observed with TG and FT-IR spectra that the impregnated fibre had lower moisture uptake than the control and there was no significant increase in thermal stability of the impregnated fibre. The sequence of fibre decomposition started from the evaporation of moisture, hemicelluloses, cellulose, lignin and finally ash content and the presence of these components were proven by FT-IR spectra. For the composite specimens, due to the high interfacial bonding of the impregnated fibre and the matrix, the impregnated composites showed consistently higher tensile strength, tensile modulus, elongation at break, flexural strength, flexural modulus and toughness than the control samples. It was also observed that 30 % fibre loading gave optimum properties. 相似文献
129.
Naseem Akhtar Narsi V. Badami Richard J. W. Cremlyn Kenneth J. Goulding 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3):293-298
Abstract o-Methoxyphenyl-, N-phenyl-N′,N′-dimethyl, and N-3-acetylphenyl-urea with chlorosulfonic acid gave 4-methoxy-3-ureido, 4-(N′,N′-dimethylureido)-, and N-3-acetylureido-benzenesulfonyl chlorides respectively. However, attempts to chlorosulfonate phenylthiourea were unsuccessful; the product was the zwitterionic sulfonic acid which did not give the sulfonyl chloride with phosphorus pentachloride. N-Phenyl-N′-p-tolyl urea by reaction with chlorosulfonic acid afforded the corresponding 4-sulfonyl chloride. N-Phenyl-N′-2-pyridyl- and N-phenyl-N′-2-thiazolyl thioureas reacted similarly. In contrast, N-phenyl-N′-2′-pyridylurea only gave the bis-sulfonyl chloride. Selected ureido-sulfonyl chlorides have been condensed with hydrazine and sodium azide and some reactions of the sulfonyl azides examined. Acetylation of phenylurea gave only the N-(3-acetyl)- or the S-acetyl derivative depending on the conditions. Contrary to previous work, it is not considered that the N-(l-acetyl) phenylthiourea is formed. 相似文献
130.
R. J. W. Cremlyn N. Akhtar I. Khattak 《Phosphorus, sulfur, and silicon and the related elements》2013,188(2):205-209
Abstract The preparation of cholesteryl phosphorodichloridite (2) is described; this compound with aniline (2 mol. equiv.) gave the N-phenylphosphoramidochloridite (5) and the latter by condensation with water afforded the N-phenyl-amidophosphite (6). Similarly the N-phenylphosphoramidochloridite (5) with morpholine gave the morpholidite (7); phenylhydrazine gave the hydrazinophosphite (8) and ethanol the amidoethyl phosphite (9). Cholesteryl phosphorodichloridite (2) by reaction with aniline (4 mol. equiv.) gave the N,N 1?diphenylphosphorodiamidite (10). The reaction of cholesteryl phosphorodichloridite (2) with methanol and ethanol are discussed in relation to the analogous reactions with cholesteryl phosphorodichloridate. Boiling ethanol gave cholesterol as the only isolatable product but at room temperature a low yield of the diethylphosphite (11; R=Et) was obtained. The yield of the phosphite was greatly increased in the presence of base. Similarly the dichloridite 2 with boiling water gave cholesterol (1), but at room temperature cholesteryl phosphite 3 was isolated: the mechanistic basis for these different results is briefly discussed. trans-4-t-Butylcyclohexanol with phosphorus trichloride gave the phosphorodichloridite, which was characterised by conversion to the corresponding N,N 1?diphenylphosphorodiamidite. 相似文献