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941.
在电工与电子技术课程中融入素质教学的实践 总被引:1,自引:0,他引:1
陈新华 《电气电子教学学报》2001,23(2):50-51
针对当前教育改革的形势,对在《电工电子技术》课程改革中推行素质 教育的重要性和必要性进行了论述,结合实践介绍了把素质教育融入课程教学改革中的新模式。 相似文献
942.
L.?Marié J.?Burguete F.?DaviaudEmail author J.?Léorat 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,33(4):469-485
A numerical study of the magnetic induction equation has
been performed on von Kármán type flows. These flows are
generated by two co-axial counter-rotating propellers in
cylindrical containers. Such devices are currently used in the
von Kármán sodium (VKS) experiment designed to study dynamo
action in an unconstrained flow. The mean velocity fields have
been measured for different configurations and are introduced in
a periodic cylindrical kinematic dynamo code. Depending on the
driving configuration, on the poloidal to toroidal flow ratio
and on the conductivity of boundaries, some flows are observed
to sustain growing magnetic fields for magnetic Reynolds numbers
accessible to a sodium experiment. The response of the flow to
an external magnetic field has also been studied: The results
are in excellent agreement with experimental results in the
single propeller case but can differ in the two propellers case. 相似文献
943.
F. Crisciani R. Purini 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,31(4):571-575
The present note deals with Munk's ocean model and proposes an alternative approach to find its solution, with special regard
to the western boundary layer. We introduce a suitable “distance” between the related Sverdrup streamfunction and all the
admissible streamfunctions which are valid in the western boundary layer. We prove that such distance has a minimum that singles
out a unique solution. Unlike the traditional method, this procedure works without assuming a priori any dynamic boundary
condition.
Received 16 July 2002 Published online 6 March 2003
RID="a"
ID="a"e-mail: fulcri@itt.ts.cnr.it 相似文献
944.
Guoen Hu 《Journal of Mathematical Analysis and Applications》2003,283(2):351-361
boundedness is considered for the commutator of higher-dimensional Marcinkiewicz integral. Some conditions implying the and the boundedness for the commutator of the Marcinkiewicz integral are obtained. 相似文献
945.
Closed kernel systems of the coalition matrix turn out to correspond to cones of games on which the core correspondence is
additive and on which the related barycentric solution is additive, stable and continuous. Different perfect cones corresponding
to closed kernel systems are described.
Received: December 2001/Revised: July 2002
RID="*"
ID="*" This note contains the new results, which were presented by the first author in an invited lecture at the XIV Italian
Meeting on Game Theory and Applications in Ischia, July 2001. The lecture was dedicated to Irinel Dragan on the occasion of
his seventieth birthday. 相似文献
946.
947.
Zheng-qiu Zhang Xian-wu Zeng Zhi-cheng WangCollege of Mathematics Wuhan University Wuhan . China College of Mathematics. Hunan University Changsha China 《应用数学学报(英文版)》2003,19(4):691-702
Abstract By using the continuation theorem of coincidence degree theory,the existence of a positive periodicsolution for a nonautonomous diffusive food chain system of three species. dx_1(t)/dt=x_1(t)[r_1(t)-a_(11)(t)x_1(t)-a_(12)(t)x_2(t)]+D_1(t)[y(t)-x_1(t)], dx_2(t)/dt=x_2(t)[-r_2(t)+a_(21)(t)x_1(t-r_1)-a_(22)(t)x_2(t)-a_(23)(t)x_3(t)], dx_3(t)/dt=x_3(t)[-r_3(t)+a_(32)(t)x_2(t-r_2)-a_(33)(t)x_3(t)], dy(t)/dt=y(t)[r_4(t)-a_(44)(t)y(t)]+D_2(t)[x_1(t)-y(t)]+D_2(t)[x_1(t)-y(t)],is established,where,r_i(t),a_(ii)(t)(i=1,2,3,4),D_i(t)(i=1,2),a_(12)(t),a_(21)(t),a_(23)(t)and a_(32)(t) are all positiveperiodic continuous functions with period w>0,T_i(i=1,2)are positive constants. 相似文献
948.
Ralph Kummetz 《Applied Categorical Structures》2003,11(1):3-25
This paper investigates function spaces of structures consisting of a partially ordered set together with some directed family of projections.More precisely, given a fixed directed index set (I,), we consider triples (D,,(p
i
)
iI
) with (D,) a poset and (p
i
)
iI
a monotone net of projections of D. We call them (I,)-pop's (posets with projections). Our main purpose is to study structure preserving maps between (I,)-pop's. Such homomorphisms respect both order and projections.Any (I,)-pop is known to induce a uniformity and thus a topology. The set of all homomorphisms between two (I,)-pop's turns out to form an (I,)-pop itself. We show that its uniformity is the uniformity of uniform convergence. This enables us to prove that properties such as completeness and compactness transfer to function pop's.Concerning categorical properties of (I,)-pop's, we will see that we are in a lucky situation from a computer scientist's point of view: we obtain Cartesian closed categories. Moreover, by a D
-construction we get (I,)-pop's that are isomorphic to their own exponent. This yields new models for the untyped -calculus. 相似文献
949.
We give a sufficient and necessary condition that a domain is biholomorphic to the classical domain. 相似文献
950.
Mbekhta's subspaces and a spectral theory of compact operators 总被引:4,自引:0,他引:4
Let be an operator on an infinite-dimensional complex Banach space. By means of Mbekhta's subspaces and , we give a spectral theory of compact operators. The main results are: Let be compact. . The following assertions are all equivalent: (1) 0 is an isolated point in the spectrum of (2) is closed; (3) is of finite dimension; (4) is closed; (5) is of finite dimension; . sufficient conditions for to be an isolated point in ; . sufficient and necessary conditions for to be a pole of the resolvent of .