Fiber optic transversal filters for RF direction finding

A wide-band electro-optic direction-finding (DF) processor employing a network of fiber optic delay lines is described. This DF filter offers a potential instantaneous bandwidth of 20 GHz and allows for multiple, simultaneous beam-angular responses with peaks that are independent of frequency. Preliminary results of an eight-laser feasibility test model DF device with two transversal filters show good agreement between predicted and measured angular responses. This experimental matched-delay filter operates in the 200–1,000 MHz frequency range and can simultaneously monitor two angles of arrival. The laboratory results obtained in this investigation suggest that the fiber optics matched-delay filter can be useful for wide-band direction finding.     

基于CPLD的线阵CCD的驱动电路设计与实现

CCD驱动时序电路的设计实现是其应用的关键问题。该文在分析TCD1209D线阵CCD的工作原理和驱动时序等特性的基础上,提出了一种基于CPLD的线阵CCD驱动电路的设计方法,其中选用MAXII系列CPLD作为硬件设计平台,运用VHDL语言设计驱动时序电路。该设计使用ouartusII软件对所设计的驱动程序进行了仿真,仿真与实验结果表明该方案设计可行,电路结构简单,集成度较高,实用性强,并具有一定通用性。     

Coloured peak algebras and Hopf algebras

For G a finite abelian group, we study the properties of general equivalence relations on G _n = G ⁿ ⋊ _n , the wreath product of G with the symmetric group _n , also known as the G-coloured symmetric group. We show that under certain conditions, some equivalence relations give rise to subalgebras of G _n as well as graded connected Hopf subalgebras of ⨁ _{n≥ o} G _n . In particular we construct a G-coloured peak subalgebra of the Mantaci-Reutenauer algebra (or G-coloured descent algebra). We show that the direct sum of the G-coloured peak algebras is a Hopf algebra. We also have similar results for a G-colouring of the Loday-Ronco Hopf algebras of planar binary trees. For many of the equivalence relations under study, we obtain a functor from the category of finite abelian groups to the category of graded connected Hopf algebras. We end our investigation by describing a Hopf endomorphism of the G-coloured descent Hopf algebra whose image is the G-coloured peak Hopf algebra. We outline a theory of combinatorial G-coloured Hopf algebra for which the G-coloured quasi-symmetric Hopf algebra and the graded dual to the G-coloured peak Hopf algebra are central objects. 2000 Mathematics Subject Classification Primary: 16S99; Secondary: 05E05, 05E10, 16S34, 16W30, 20B30, 20E22Bergeron is partially supported by NSERC and CRC, CanadaHohlweg is partially supported by CRC     

Asymptotic stability at infinity for differentiable vector fields of the plane

Let be a differentiable (but not necessarily C¹) vector field, where σ>0 and . Denote by R(z) the real part of z∈C. If for some ?>0 and for all , no eigenvalue of DpX belongs to , then: (a) for all , there is a unique positive semi-trajectory of X starting at p; (b) it is associated to X, a well-defined number I(X) of the extended real line [−∞,∞) (called the index of X at infinity) such that for some constant vector v∈R² the following is satisfied: if I(X) is less than zero (respectively greater or equal to zero), then the point at infinity ∞ of the Riemann sphere R²∪{∞} is a repellor (respectively an attractor) of the vector field X+v.     

Exact algorithms for the Hamiltonian cycle problem in planar graphs

We construct an exact algorithm for the Hamiltonian cycle problem in planar graphs with worst case time complexity , where c is some fixed constant that does not depend on the instance. Furthermore, we show that under the exponential time hypothesis, the time complexity cannot be improved to .     

Planar binary trees and perturbative calculus of observables in classical field theory

We study the Klein–Gordon equation coupled with an interaction term (□+m²)φ+λφ^p=0. In the linear case (λ=0) a kind of generalized Noether's theorem gives us a conserved quantity. The purpose of this paper is to find an analogue of this conserved quantity in the interacting case. We will see that we can do this perturbatively, and we define explicitly a conserved quantity, using a perturbative expansion based on Planar Trees and a kind of Feynman rule. Only the case p=2 is treated but our approach can be generalized to any ^p-theory.     

无符号拉普拉斯谱半径的新上界

如果一个图存在定向满足其最大出度△~＋不超过最大度△的一半,则通过估计图的半边路径（semi-edge walk）的个数,得到了该图的无符号拉普拉斯谱半径的一个新上界.进而根据D.Goncalves对平面图边分解的结果,得到了平面图无符号拉普拉斯谱半径的一个新上界.     

Three coordination polymers built from planar tetranuclear clusters and 5-sulfoisophthalic acid

Three coordination polymers built from planar tetranuclear clusters and H₃sip ligands, Pb₂Cl(sip)(bipy) (1), Pb₂Br(sip)(H₂O) (2), and Ni₄(sip)₂(pyz)₂(H₂O)₈(OH)₂·2H₂O (3) (H₃sip?=?5-sulfoisophthalic acid, bipy?=?2,2′-bipyridine, and pyz?=?pyrazine), have been hydrothermally synthesized and characterized by IR, TGA, and single-crystal X-ray diffraction. Compound 1 features a 2-D layer-like structure containing tetranuclear square [Pb₄(SO₃)₂] clusters. Complex 2 has a 3-D open framework architecture constructed from tetranuclear cluster [Pb₄Br₂(SO₃)₂] inorganic building blocks. The tetranuclear units, [Ni₄(OH)₂(COO)₄], in 3 are interlinked through carboxylates and µ₂-pyz ligands to generate a 2-D layer structure. The connecting modes between tetranuclear clusters and organic ligands in the three compounds are discussed in this article. In the solid state at room temperature, yellow photoluminescence in 1 and 2 are observed.     

Acetylcholine Receptor-Based Biosensor

Abstract

The acetylcholine (ACh) receptor protein isolated from Torpedo electric organ was incorporated into asolectin liposomes and immobilized noncovalently on the surface of a Planar Interdigitated Capacitive sensor to produce an ACh receptor-based biosensor. Capacitance of the biosensor, which was stable in buffered saline, increased rapidly when ACh was added. The response was dosedependent and specific for ACh, and the biosensor did not respond to six other neurotransmitters. Impure receptor preparations containing ACh esterase produced a smaller signal in response to ACh but showed enhanced response after inhibition of ACh esterase with diisopropylfluorophosphate.

The competitive antagonist d-tubocurare, and the noncompetitive antagonist amantadine, inhibited the response of the biosensor to ACh, but a time-dependent recovery occurred upon perfusion with ACh. The irreversible antagonist α-neurotoxin inhibited the response and there was no recovery following perfusion with ACh. Thus, the pharmacologic profile of the biosensor in response to drugs closely resembled that of the nicotinic ACh receptor.