共查询到20条相似文献,搜索用时 31 毫秒
1.
Yongjun Tian Tiansheng Wang Ke Chen Lie Chen Dongning Zheng Hanhong Qi Sven Linzen Frank Schmidl Paul Seidel 《中国科学A辑(英文版)》2000,43(1):82-87
A flip-chip-type gradiometer has been constructed with a 10 mm × 5 mm planar DCSQUID gradiometer fabricated on a SrTiO3 bicrystal substrate and a flux transformer made from a YBCO*/YBCO/CeO2/YSZ multilayer on ϕ50.8 mm Si wafer. The coupling coefficient between the flux transformer and the planar gradiometer is
0.18. The transformer increases effectively the resolution of the gradiometer. A magnetic field gradient resolution of 73
fT.cm−1Hz−1/2 in the white region and 596 fT.cm−1Hz−1/2 at 1 Hz has been obtained. High quality magnetocardiogram signals have been successfully measured by using this flip-chip-type
gradiometer in an unshielded environment. 相似文献
2.
Biaobing Jin Lin Kang Ruixin Wu Jianyu Zhang Qiheng Cheng Peiheng Wu Dong Jing Gang Jiao Kai Shao Mingming Jiang Jiazong Zhang Minsong Sun Yunyi Wang Yueliang Zhou Huibin Lü Shifa Xu Meng He Xiaoping Wang Bingchuan Yang Jian Lu Qishao Zhang 《中国科学A辑(英文版)》1997,40(2):219-224
A high-T
c superconducting (HTSC) thin film/GaAs MESFET hybrid microwave oscillator operated at 10.6 GHz has been designed, fabricated
and characterized. Microstrip line structures were used throughout the circuit with superconducting thin film YBa2Cu3O7-δ(YBCO) as the conductor material. The YBCO thin films were deposited on 15 mm×10 mm×0.5 mm LaAlO3 substrates. The oscillator was common-source, series feedback type using a GaAs-MESFET (NE72084) as the active device and
a superconducting microstrip resonator as the frequency stabilizing element. By improving the unloaded quality factorQ
0 of the superconducting microstrip resonator and adjusting the coupling coefficient between the resonator and the gate of
the MESFET, the phase noise of the oscillator was decreased. At 77 K, the phase noise of the oscillator at 10 kHz offset from
carrier was −87 dBc/Hz.
Project supported by the National Center for Research and Development on Superconductivity of China. 相似文献
3.
V. D. Mazurov 《Algebra and Logic》1998,37(6):371-379
For G a finite group, ω(G) denotes the set of orders of elements in G. If ω is a subset of the set of natural numbers, h(ω)
stands for the number of nonisomorphic groups G such that ω(G)=ω. We say that G is recognizable (by ω(G)) if h(ω(G))=1. G
is almost recognizable (resp., nonrecognizable) if h(ω(G)) is finite (resp., infinite). It is shown that almost simple groups
PGLn(q) are nonrecognizable for infinitely many pairs (n, q). It is also proved that a simple group S4(7) is recognizable, whereas A10, U3(5), U3(7), U4(2), and U5(2) are not. From this, the following theorem is derived. Let G be a finite simple group such that every prime divisor of
its order is at most 11. Then one of the following holds: (i) G is isomorphic to A5, A7, A8, A9, A11, A12, L2(q), q=7, 8, 11, 49, L3(4), S4(7), U4(3), U6(2), M11, M12, M22, HS, or McL, and G is recognizable by the set ω(G); (ii) G is isomorphic to A6, A10, U3(3), U4(2), U5(2), U3(5), or J2, and G is nonrecognizable; (iii) G is isomorphic to S6(2) or O
8
+
(2), and h(ω(G))=2.
Supported by RFFR grant No. 96-01-01893.
Translated fromAlgebra i Logika, Vol. 37, No. 6, pp. 651–666, November–December, 1998. 相似文献
4.
V. P. Burichenko 《Algebra and Logic》2008,47(6):384-394
Let G = SL(n, q), where q is odd, V be a natural module over G, and L = S2(V) be its symmetric square. We construct a 2-cohomology group H2(G, L). The group is one-dimensional over F
q if n = 2 and q ≠ 3, and also if (n, q) = (4, 3). In all other cases H2(G, L) = 0. Previously, such groups H2(G, L) were known for the cases where n = 2 or q = p is prime. We state that H2(G, L) are trivial for n ⩾ 3 and q = pm, m ⩾ 2. In proofs, use is made of rather elementary (noncohomological) methods.
__________
Translated from Algebra i Logika, Vol. 47, No. 6, pp. 687–704, November–December, 2008. 相似文献
5.
V. D. Mazurov 《Algebra and Logic》1997,36(1):23-32
For a finite group G, ω(G) denotes the set of orders of its elements. If ω is a subset of the set of natural numbers, h(ω)
stands for the number of pairwise nonisomorphic finite groups G for which ω(G)=ɛ. We prove that h(ω(G))=1, if G is isomorphic
to S9, S11, S12, S13, or A12, and h(ω(G))=2 if G is isomorphic to S2(6) or to O
8
+
(2). 01
Supported by RFFR grant No. 96-01-01893.
Translated fromAlgebra i Logika, Vol. 36, No. 1, pp. 37–53, January–February, 1997. 相似文献
6.
A. I. Sozutov 《Algebra and Logic》2007,46(3):195-199
An involution j of a group G is said to be almost perfect in G if any two involutions in jG whose product has infinite order are conjugated by a suitable involution in jG. Let G contain an almost perfect involution j and |CG(j)| < ∞. Then the following statements hold: (1) [j,G] is contained in an FC-radical of G, and |G: [j,G]| ⩽ |CG(j)|; (2) the commutant of an FC-radical of G is finite; (3) FC(G) contains a normal nilpotent class 2 subgroup of finite
index in G.
__________
Translated from Algebra i Logika, Vol. 46, No. 3, pp. 360–368, May–June, 2007. 相似文献
7.
Let G be an outerplanar graph with maximum degree △. Let χ(G^2) and A(G) denote the chromatic number of the square and the L(2, 1)-labelling number of G, respectively. In this paper we prove the following results: (1) χ(G^2) = 7 if △= 6; (2) λ(G) ≤ △ +5 if △ ≥ 4, and ),(G)≤ 7 if △ = 3; and (3) there is an outerplanar graph G with △ = 4 such that )λ(G) = 7. These improve some known results on the distance two labelling of outerplanar graphs. 相似文献
8.
We study the spectrum of the boundary-value problem for the Laplace operator in a thin domain Ω(ε) obtained by small perturbation
of the cylinder Ω(ε)=ω×(-ε/2.ε/2) ⊂ ℝ3in a neighborhood of the lateral surface. The Dirichlet condition is imposed on the bases of the cylinder, and the Dirichlet
condition or the Neumann condition is imposed on the remaining part of ∂Ω(ε). We construct and justify asymptotic formulas
(as ε→+0) for eigenvalues and eigenfunctions. In view of a special form of the lateral surface, there are eigenfunctions of
boundary-layer type that exponentially decrease far from the lateral surface. For the mixed boundary-value problem such a
localization is possible in neighborhoods of local maxima of the curvature of the contour ∂ω. This property of eigenfunctions
is a characteristic feature of the first points of the spectrum (in particular, the first eigenvalue) and, under the passage
from Ω(h)() to Ω(h), the spectrum itself has perturbation O(h−2). Bibliography: 29 titles.
Translated fromProblemy Matematicheskogo Analiza, No. 19, 1999, pp. 105–149. 相似文献
9.
To solve the stochastic equations for fluctuating potentials in donor-acceptor systems with low compensations K, an asymptotic
perturbation theory is elaborated and a correction to the Fermi level of impurity electrons is calculated: δμ(K) = c1K + c2K3/2 + c3K2
log(1/K) + c4K2. The constants ci are an asymptotic series in the powers of α = 0.23 with coefficients depending on Λ, where 1/Λ is the mean size of the local
two-acceptor complex. The constant c1 is proportional to Λ. Thus, despite the low compensation of two-acceptor local complexes, their structure determines the
leading term of the asymptotic behavior of δμ(K).
Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 112, No. 2, pp. 295–307, August, 1997. 相似文献
10.
Ion beam assisted pulsed laser deposition of biaxially aligned yttria-stabilized zirconia (YSZ) was used to produce a buffer
layer for YBCO film on polycrystalline metallic substrate. The YSZ layers were biaxially aligned with (001) axis normal to
the substrate. The minimum FWHM of (111) phi-scan of the YSZ was 19°, and the minimum FWHM of the rocking curve of YSZ was
4.5°. Highly c-axis oriented biaxially aligned YBCO thin films were epitaxially grown by laser ablation on these layers, with
JC(77K, 0T) = 2.1 × 105 A/cm2,
.
Project supported by the National Center for R&D on Superconductivity of China. 相似文献
11.
O. G. Parfenov 《Journal of Mathematical Sciences》1998,92(1):3630-3634
The Gelfand widths of the unit ball of H2(ν) (the weighted Hardy space) with respect to the metric of the space L∞(Tr) are considered (here Tr is the circle of radius r centered at the origin), as well as the Bernstein widths of the unit ball of H∞ with respect to the metric of the space L2(Tr, μ). Asymptotic formulas for the widths in question are established for arbitrary measures ν, μ. Bibliography: 5 titles.
Translated fromZapiski Nauchnykh Seminarov POMI, Vol. 232, 1996, pp. 134–140.
Translated by S. V. Kislyakov. 相似文献
12.
S. V. Kislyakov 《Journal of Mathematical Sciences》1981,16(3):1102-1108
Let A be a closed subalgebra of the complex Banach algebra C(S), containing the constant functions. We assume that one has
found a probability measureμ on S and a function F from L∞(μ) such that: 1)|F|= 1 a.e. relative to μ; 2) F
μ
ε A1; 3) F is a limit point of the unit ball of the algebra A in the topology δ(L∞(μ), L1(μ)). One proves in the paper that under these conditions the space A** contains a complement space, isometric to H∞. The measure μ and the function F, satisfying the conditions l)-3) indeed exist if the maximal ideal space of the algebra
A contains a non-one-point part (and it is very likely that such aμ. and F exist whenever the algebra A is not self-adjoint). Thus, the above-formulated result allows us to extend A. Pelczynski's
theorem (Ref, Zh. Mat., 1975, 1B894) regarding the space H∞ to a very broad class of uniform algebras.
Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR,
Vol. 65, pp. 80–89, 1976. 相似文献
13.
14.
M. E. Dudkin 《Ukrainian Mathematical Journal》1998,50(6):888-900
We give a criterion of invariance and symmetry of the restriction of an arbitrary unbounded self-adjoint operator in the space
L
2(ℝn, dx) by using the introduced notion of support of an arbitrary vector and the notion of capacity of a subspace N ⊂ ℝn.
Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 50, No. 6, pp. 781–791, June, 1998.
This work was partially supported by the Foundation for Fundamental Research of the Ministry of Science and Technology of
the Ukraine (grant No. 1/238 “Operator”). 相似文献
15.
Let Τ be the Baby Monster graph which is the graph on the set of {3,4}-transpositions in the Baby Monster group B in which two such transpositions are adjacent if their product is a central involution in B. Then Τ is locally the commuting graph of central (root) involutions in 2
E
6(2). The graph Τ contains a family of cliques of size 120. With respect to the incidence relation defined via inclusion these
cliques and the non-empty intersections of two or more of them form a geometry ℰ(B) with diagram for t=4 and the action of B on ℰ(B) is flag-transitive. We show that ℰ(B) contains subgeometries ℰ(2
E
6(2)) and ℰ(Fi
22) with diagrams c.F
4(2) and c.F
4(1). The stabilizers in B of these subgeometries induce on them flag-transitive actions of 2
E
6(2):2 and Fi
22:2, respectively. The geometries ℰ(B), ℰ(2
E
6(2)) and ℰ(Fi
22) possess the following properties: (a) any two elements of type 1 are incident to at most one common element of type 2 and (b) three elements of type 1 are pairwise incident to common elements of type 2 if and only if they are incident to a common
element of type 5. The paper addresses the classification problem of c.F
4(t)-geometries satisfying (a) and (b). We construct three further examples for t=2 with flag-transitive automorphism groups isomorphic to 3⋅2E2:2, E6(2):2 and 226 .F4(2) and one for t=1 with flag-transitive automorphism group 3⋅Fi
22:2. We also study the graph of an arbitrary (non-necessary flag-transitive) c.F
4(t)-geometry satisfying (a) and (b) and obtain a complete list of possibilities for the isomorphism type of subgraph induced by the common neighbours of a pair
of vertices at distance 2. Finally, we prove that ℰ(B) is the only c.F
4(4)-geometry, satisfying (a) and (b).
Oblatum 20-X-1999 & 2-I-2001?Published online: 5 March 2001 相似文献
16.
17.
We study the mod p homology of the double and the triple loop spaces of exceptional Lie groups E
6, E
7, and E
8 through the Eilenberg–Moore spectral sequence and the Serre spectral sequence using homology operations. The Bockstein actions
on them are also determined. As a result, the Eilenberg–Moore spectral sequences of the path loop fibrations converging to
H
*(Ω2
G;?
p
) and H
*(Ω3
G;?
p
) collapse at the E
2-term for any compact simple Lie group G.
Received: 11 November 1999 相似文献
18.
Andrei Heilper 《Israel Journal of Mathematics》1979,34(1-2):1-11
Let {Zn=1{(
n
∓
) bea sequence of points in the unit open disk, and letNϕ(U) denote the class of functionsf analytic in the unit disk U such that |f|∈L (
ϕ
1
)(U). For ϕ ≡ 1, the necessary and sufficient conditions for the existence off εN(U) and vanishing atz
n is Σ(
n=1
∓
) (1–|Zn|)2 ∞. Also we estimate a large family of canonical products. These results are extended to ϕ(z)=(1-|z|)ϕ.
This represents a part of a Ph.D. thesis conducted at the Technion — Israel Institute of Technology, Department of Mathematics,
by Dr. C. A. Horowitz. His help during the preparation of this paper is gratefully acknowledged. 相似文献
19.
It is proved that a finite group isomorphic to a simple non-Abelian group L3(2m) or U3(2m) is, up to isomorphism, recognizable by a set of its element orders. On the other hand, for every simple group S=S4(2m), there exist infinitely many pairwise non-isomorphic groups G with w(G)=w(S). As a consequence, we present a list of all
recognizable finite simple groups G, for which 4t ∉ ω(G) with t>1.
Supported by RFFR grant No. 99-01-00550, by the National Natural Science Foundation of China (grant No. 19871066), and by
the State Education Ministry of China (grant No. 98083).
Translated fromAlgebra i Logika, Vol. 39, No. 5, pp. 567–585, September–October, 2000. 相似文献
20.
N. M. Timofeev 《Mathematical Notes》1997,61(3):321-332
Let τk(n) be the number of representations ofn as the product ofk positive factors, τ(n)=τ(n). The asymptotics of Σ
n≤x
τ
k
(n)τ(n+1) for 80k
10 (lnlnx)3≤lnx is shown to be uniform with respect tok.
Translated fromMatematicheskie Zametki, Vol. 61, No. 3, pp. 391–406, March, 1997.
Translated by N. K. Kulman 相似文献