圆锥形血管中的振荡发展流动

本文在小锥度角的假设下,研究了圆锥形血管的非定常振荡的发展流动问题.导得了相应的速度分布公式.分析表明,所有收缩的圆锥形血管的流动都是发展流动,而且锥度角对发展流动的影响随着锥度角的增大而增大.     

Matrix Analysis to Additive Schwarz Methods

1.IntroductionWeconsiderthefollowingsecondorderellipticboundaryvalueproblem:Lu=f,infl,(1)u=o,onOfl,(2)whereLisaselfadjointpositiveoperatorandflCnd(15dS3)isapolyhedraldomain.Aweaksolutionhasthefollowingform:FinduEHf(fl)suchthat:LetVh:=M=Span{rki},where{ghi}couldbenodalbasisconsistingofpiece-wiselinearfunctionsorothersplinefunctions-Substitutingthefollowingsolutionuh=Zui4iintotheaboveweakformleadstoadiscreteequationAu=f,(3)whereA=(crij),oij=A(ofi,rkj).(4)Itiswellknownthatthec0efficientmat…     

关于分光计调整方法的分析

本文对自准直调节方法的成像规律和光栅侧向倾斜对测量结果的影响等问题,进行了半定量分析,给出了相关的调节依据和正确的调节步骤     

A Near-Resonance Solution to the Bloch Equations and Its Application to RF Pulse Design

A near-resonance expansion of the solution to the Bloch equations in the presence of a radiofrequency (RF) pulse is presented in this paper. The first-order approximation explicitly demonstrates the nonlinear nature of the Bloch equations and precisely relates the excitation profile with the RF pulse when the flip angle is less than π/2. As an application of this solution, we present a procedure for designing RF pulses to generate symmetric excitation profiles with arbitrary shapes for new encoding approaches such as wavelet encoding.     

A dynamical mechanism for quark mixing and neutrino oscillations

We show that, if one assumes fermion generations to be given by a gauge symmetry, together with a certain Higgs mechanism for breaking it, then the known empirical features of quark and lepton mixing can be largely explained, including, in particular, the fact that the mixing (CKM) matrix element , responsible for the muon anomaly in atmospheric neutrinos, is near maximal, and much larger than its quark counterparts and , while the corner elements for both quarks () and leptons () are all very small. The mechanism also automatically gives a hierarchical fermion-mass spectrum which is intimately related to the mixing pattern. Received: 8 February 1999 / Published online: 15 July 1999     

Geometric Applications of a Randomized Optimization Technique

We propose a simple, general, randomized technique to reduce certain geometric optimization problems to their corresponding decision problems. These reductions increase the expected time complexity by only a constant factor and eliminate extra logarithmic factors in previous, often more complicated, deterministic approaches (such as parametric searching). Faster algorithms are thus obtained for a variety of problems in computational geometry: finding minimal k -point subsets, matching point sets under translation, computing rectilinear p -centers and discrete 1-centers, and solving linear programs with k violations. Received May 23, 1998, and in revised form March 29, 1999.     

Synthesis of quinolines by ruthenium-catalyzed heteroannulation of anilines with 3-amino-1-propanol

Anilines react with 3-amino-1-propanol in dioxane in the presence of a catalytic amount of a ruthenium catalyst and tin(II) chloride dihydrate together with a hydrogen acceptor to afford the corresponding quinolines in moderate yields.     

Synthesis of spiroisoindolinones by palladium-catalyzed heterocyclization of 2-iodobenzoyl chloride with ketimines

2-Iodobenzoyl chloride reacts with ketimines in acetonitrile at 100° under carbon monoxide pressure in the presence of a catalytic amount of a palladium catalyst together with triethylamine to afford the corresponding spiroisoindolinones in high yields.     

Synthesis of 3-phenoxy-1,3-dihydro-1-isobenzofuranones by palladium-catalyzed carbonylative cyclization of 2-bromobenzaldehyde with phenols

2-Bromobenzaldehyde reacts with phenols in acetonitrile under carbon monoxide pressure in the presence of a catalytic amount of bis(triphenylphosphine)palladium(II) chloride to afford the corresponding 3-phenoxy-1,3-dihydro-1-isobenzofuranones in high yields.     

Determination of breath alcohol using a differential-type amperometric biosensor based on alcohol dehydrogenase

A differential-type amperometric biosensor based on conventional thick-film technology has been developed for breath alcohol measurement. The amperometric breath alcohol biosensor utilizes the alcohol dehydrogenase (ADH) and nicotinamide adenine dinucleotide (NAD⁺) cofactor which produce reduced NADH as a product of the oxidation of alcohol. The biosensor was designed in a differential format consisting of a common Ag/AgCl reference electrode, an active working electrode containing the ADH, and the inactive working electrode containing only bovine serum albumin instead of the ADH. The differential signal between the active working electrode and the inactive working electrode minimized the interference from a large number of oxidizable species present in a person's breath. Prior to the amperometric measurement the biosensor was hydrated simply by dipping it into a phosphate buffer solution at pH 7.4. The NADH produced from the enzymatic reaction was oxidized at the working electrode biased at a potential of 470 mV vs. an on-board Ag/AgCl reference electrode. The biosensor can measure a person's breath alcohol over the concentration range 20–800 ppm routinely required in a test of drunken driving.