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31.
D.E. Caro E. Gold A.G. Klein C.E. MacDowell G.I. Opat J.W.G. Wignall 《Nuclear Physics B》1973,52(1):239-247
We present differential cross sections for elastic d scattering at beam momenta 0.735 and 0.940 GeV/c and momentum transfers in the range 0.04<|t|<0.5(GeV/c)2. The d elastic differential cross section is expressed in terms of a deutron form factor and the I=0 t-channel exchange N amplitudes, enabling us to isolate the corresponding I=0 t-channel exchange cross sections. 相似文献
32.
33.
Robert Gold 《Journal of Number Theory》1974,6(5):369-373
Let k be a J-field, K the basic Zl-extension of k, and A0, A the l-class groups of k, K respectively. It is known that if A01?J is nontrivial, then is infinite. It is shown that this result is still true if the classes represented by the primes lying over l are factored out from both groups. This is applied to and A0 = (0) for information on the invariants λ and μ. There are such k for which λ ≥ 2. 相似文献
34.
This paper describes a flow-injection (FI) method for the simultaneous determination of aniline and cyclohexylamine impurities in cyclamate products. The method consists of the derivatization of amines with 1,2-naphthoquinone-4-sulfonate under selective and non-selective conditions. Here, the selectivity is achieved by working at 20 degree C, at which only aniline reacts, whilst higher temperatures (80 degree C) lead to a non-selective reaction of the two analytes. The FI manifold is composed of two flow cells for the spectrophotometric detection of derivatives at 480 nm. Experimental conditions have been optimized by factorial design and multicriteria making approach. Quantification is accomplished by differential analysis of the analyte contributions in the double peaks generated when the sample reaches cell 1 and cell 2. Results obtained with the proposed method are in satisfactory agreement with those provided by the standard method for the analysis of cyclamate samples. 相似文献
35.
36.
The effect of charge stratification by direct, in-cylinder injection of a small quantity of propane-air mixture in a single-cylinder,
propane-fuelled, spart-ignition engine, has been determined in terms of in-cylinder pressure, flame visualisation and exhaust
emissions. The operating conditions ranged from low load to wide open throttle at 1000 and 1500 rpm, and with quiescent and
swirling in-cylinder flows. The effects of injection-driven flow and turbulence on combustion have been considered independently
of mixture strength by assessing the consequences of injecting a local mixture of an equivalence ratio equal to that of the
port-induced charge.
The results provide further evidence to support the concept of direct in-cylinder mixture injection. At 1000 rpm and low load,
faster development of the flame kernel and subsequent enflamed area were observed, together with a 60% increase in peak cylinder
combustion pressure at an overall equivalence ratio of 0.7 (A/F of 22.5). The relative effect of local-charge stratification increased with reduction in equivalence ratio at this engine
speed and without increase in emissions; at 1500 rpm, stable combustion was achieved even at an equivalence ratio of 0.61
(A/F of 25.8), which was below the flammability limit of the homogeneous port-only propane/ air mixture. Unthrottled engine operation
produced similar results so that at an equivalence ratio of 0.55 (A/F of 28.5), for example, the Coefficient of variation of the indicated mean effective pressure was reduced from 0.4 to less
than 0.1 by mixture local injection. With a shrouded inlet valve generating mean gas velocities of 6 m/s at the time of ignition
in the vicinity of the spark plug, control of rich mixture injection both with and against the bulk in-cylinder flow, resulted
in stable combustion with Coefficient of variation of the indicated mean effective pressure of less than 0.1 at an equivalence
ratio of 0.55 (A/F of 28.5).
Received: 28 October 1997/Accepted: 23 March 1998 相似文献
37.
In the context of social organisms, a school refers to a cohesive group of organisms that share a common speed and direction of motion, as well as a common axis of body alignment or polarization. Schools are also noted for the relatively fixed nearest-neighbour distances between individuals. The rules of interaction that lead to the formation and maintenance of a school structure have been explored experimentally, analytically, and by simulation. Interest in biological examples, and non-biological “self-propelled particles” such as robots, vehicles, or autonomous agents leads to the question of what are the simplest possible sets of rules that can assure the formation and the stability of the “perfect school”: an aggregate in which the nearest-neighbour distances and speeds are identical.Here we explore mechanisms that lead to a perfect school structure in one and two dimensions. We consider distance-detection as well as velocity-detection between the interacting pairs of self-propelled particles. We construct interaction forces and formulate schooling equations. In the simplest cases, these equations have analytic solutions. In many cases, the stability of the perfect school can be explored. We then investigate how these structures form and evolve over time from various initial configurations using simulations. We study the relationship between the assumed interaction forces and the school patterns that emerge. While true biological schools are far from perfect, the insights gained from this investigation can help to understand some properties of real schools, and to suggest the appropriate properties of artificial schools where coordinated motion is desired. 相似文献
38.
Naveen Satrawala Kamal N. Sharma Leah C. Matsinha Latisa Maqeda Shepherd Siangwata Gregory S. Smith Raj K. Joshi 《Tetrahedron letters》2017,58(28):2761-2764
Base-catalyzed C–C cross coupling of secondary alcohols and aryl-aldehydes was achieved, when an alcoholic solution of an aryl-aldehyde was stirred under reflux for 45 h in the presence of a catalytic (20 mol%) amount of K2CO3. The consistent formation of α,α′-bis-(benzylidene) alkanones was obtained in moderate to good yields using various secondary alcohols and substituted aryl-aldehydes. Herein, α,α′-bis-(benzylidene)alkanones, which are the classical products of Claisen-Schmidt (cross aldol) condensation, have been synthesized via an alternative strategy using secondary alcohols. Bis-(benzylidene) alkanones are an integral part of various drug regimes and the production of bis-(benzylidene) alkanones without using any precious metal is a major outcome of the present reaction. 相似文献
39.
We study a new kind of online bin packing with conflicts, motivated by a problem arising when scheduling jobs on the Grid. In this bin packing problem, the set of items is given at the beginning, together with a set of conflicts on pairs of items. A conflict on a pair of items implies that they cannot be assigned to a common bin. The online scenario is realized as follows. Variable-sized bins arrive one by one, and items need to be assigned to each bin before the next bin arrives. We analyze the online problem as well as semi-online versions of it, which are the variant where the sizes of the arriving bins are monotonically non-increasing as well as the variant where they are monotonically non-decreasing. 相似文献
40.
Let G be a connected reductive algebraic group defined over an algebraically closed field of positive characteristic. We study a generalization of the notion of G-complete reducibility in the context of Steinberg endomorphisms of G. Our main theorem extends a special case of a rationality result in this setting. 相似文献