74 research outputs found
A Lefschetz type coincidence theorem
A Lefschetz-type coincidence theorem for two maps f,g:X->Y from an arbitrary
topological space X to a manifold Y is given: I(f,g)=L(f,g), the coincidence
index is equal to the Lefschetz number. It follows that if L(f,g) is not equal
to zero then there is an x in X such that f(x)=g(x). In particular, the theorem
contains some well-known coincidence results for (i) X,Y manifolds and (ii) f
with acyclic fibers.Comment: The final version, 23 pages, to appear in Fund. Mat
Higher order Nielsen numbers
Suppose X,Y are manifolds, f,g:X->Y are maps. The well-known Coincidence
Problem studies the coincidence set C={x:f(x)=g(x)}. The number m=dimX-dimY is
called the codimension of the problem. More general is the Preimage Problem.
For a map f:X->Z and a submanifold Y of Z, it studies the preimage set
C={x:f(x) in Y}, and the codimension is m=dimX+dimY-dimZ. In case of
codimension 0, the classical Nielsen number N(f,Y) is a lower estimate of the
number of points in C changing under homotopies of f, and for an arbitrary
codimension, of the number of components of C. We extend this theory to take
into account other topological characteristics of C. The goal is to find a
"lower estimate" of the bordism group Omega_{p}(C) of C. The answer is the
Nielsen group S_{p}(f,Y) defined as follows. In the classical definition the
Nielsen equivalence of points of C based on paths is replaced with an
equivalence of singular submanifolds of C based on bordisms. We let
S_{p}^{prime}(f,Y) be the quotient group of Omega_{p}(C) with respect to this
equivalence relation, then the Nielsen group of order p is the part of this
group preserved under homotopies of f. The Nielsen number N_{p}(f,Y) of order p
is the rank of this group (then N(f,Y)=N_{0}(f,Y)). These numbers are new
obstructions to removability of coincidences and preimages. Some examples and
computations are provided.Comment: New version, 18 pages. Minor revisions throughout the pape
Fixed points and selections of set-valued maps on spaces with convexity
We provide theorems extending both Kakutani and Browder fixed
points theorems for multivalued maps on topological vector spaces,
as well as some selection theorems. For this purpose we introduce
convex structures more general than those of locally convex and
non-locally convex topological vector spaces or generalized
convexity structures due to Michael, van de Vel, and Horvath
Measurement of the Bottom-Strange Meson Mixing Phase in the Full CDF Data Set
We report a measurement of the bottom-strange meson mixing phase \beta_s
using the time evolution of B0_s -> J/\psi (->\mu+\mu-) \phi (-> K+ K-) decays
in which the quark-flavor content of the bottom-strange meson is identified at
production. This measurement uses the full data set of proton-antiproton
collisions at sqrt(s)= 1.96 TeV collected by the Collider Detector experiment
at the Fermilab Tevatron, corresponding to 9.6 fb-1 of integrated luminosity.
We report confidence regions in the two-dimensional space of \beta_s and the
B0_s decay-width difference \Delta\Gamma_s, and measure \beta_s in [-\pi/2,
-1.51] U [-0.06, 0.30] U [1.26, \pi/2] at the 68% confidence level, in
agreement with the standard model expectation. Assuming the standard model
value of \beta_s, we also determine \Delta\Gamma_s = 0.068 +- 0.026 (stat) +-
0.009 (syst) ps-1 and the mean B0_s lifetime, \tau_s = 1.528 +- 0.019 (stat) +-
0.009 (syst) ps, which are consistent and competitive with determinations by
other experiments.Comment: 8 pages, 2 figures, Phys. Rev. Lett 109, 171802 (2012
The QCD transition temperature: results with physical masses in the continuum limit II.
We extend our previous study [Phys. Lett. B643 (2006) 46] of the cross-over
temperatures (T_c) of QCD. We improve our zero temperature analysis by using
physical quark masses and finer lattices. In addition to the kaon decay
constant used for scale setting we determine four quantities (masses of the
\Omega baryon, K^*(892) and \phi(1020) mesons and the pion decay constant)
which are found to agree with experiment. This implies that --independently of
which of these quantities is used to set the overall scale-- the same results
are obtained within a few percent. At finite temperature we use finer lattices
down to a <= 0.1 fm (N_t=12 and N_t=16 at one point). Our new results confirm
completely our previous findings. We compare the results with those of the
'hotQCD' collaboration.Comment: 19 pages, 8 figures, 3 table
Research and Design of a Routing Protocol in Large-Scale Wireless Sensor Networks
无线传感器网络,作为全球未来十大技术之一,集成了传感器技术、嵌入式计算技术、分布式信息处理和自组织网技术,可实时感知、采集、处理、传输网络分布区域内的各种信息数据,在军事国防、生物医疗、环境监测、抢险救灾、防恐反恐、危险区域远程控制等领域具有十分广阔的应用前景。 本文研究分析了无线传感器网络的已有路由协议,并针对大规模的无线传感器网络设计了一种树状路由协议,它根据节点地址信息来形成路由,从而简化了复杂繁冗的路由表查找和维护,节省了不必要的开销,提高了路由效率,实现了快速有效的数据传输。 为支持此路由协议本文提出了一种自适应动态地址分配算——ADAR(AdaptiveDynamicAddre...As one of the ten high technologies in the future, wireless sensor network, which is the integration of micro-sensors, embedded computing, modern network and Ad Hoc technologies, can apperceive, collect, process and transmit various information data within the region. It can be used in military defense, biomedical, environmental monitoring, disaster relief, counter-terrorism, remote control of haz...学位:工学硕士院系专业:信息科学与技术学院通信工程系_通信与信息系统学号:2332007115216
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