完全解决图$\overline{B_{n-8,1,4}}$的色等价类

Two graphs are defined to be adjointly equivalent if and only if their complements are chromatically equivalent.Using the properties of the adjoint polynomials and the fourth character R₄（G）,the adjoint equivalence class of graph B_n-8,1,4 is determined.According to the relations between adjoint polynomial and chromatic polynomial,we also simultaneously determine the chromatic equivalence class of B_n-8,1,4 that is the complement of B_n-8,1,4.     

图簇Y_(λ_kδ)∪β_kS_δ~*的伴随分解及其补图的色等价性

设P_n是具有n个顶点的路,令δ=rn+1,我们S_δ~*表示把rP_(n+1)的每个分支的一个1度点重迭在一起得到的图.用Y_(λ_1δ)~(S*)表示把r_1S_δ~*中每个分支的r度顶点与S_δ~*的r度顶点依次邻接后得到的图,Y_(λ_2δ)~(S*)表示把用r_2Y_(λ_1δ)~(S*)中每个分支的r+r1度顶点与S_δ~*的r度顶点依次邻接后得到的图,一般地,Y_(λ_kδ)~(S*)表示把用r_kY_(λ_(k-1)δ)~(S*)中每个分支的r+r_k-1度顶点与S_δ~*的r度顶点依次邻接后得到的图,运用图的伴随多项式的性质,证明了图Y_(λ_kδ)~(S*)∪β_kS_δ~*的伴随多项式的因式分解定理,进而得到了这类图的补图的色等价性.     

算子的酉等价与换位代数的K0-群

We show that two irreducible operators on Н are unitarily equivalent if and only if W^*（AФB)‘≌M2(C), and give an answer to the open question posed by J. B. Conway (Subnormal Operators, 7r Pitman, Advanced Publishing Program,Boston, London, Melbourne, 1981) for irreducible operator. We also show that if T, T1 and T2 are irreducible operators with TФT1≌TФT2, then T1≌T2. Finally, we show that K0(A(D))≌Z, giving a new result on the Ko-group of Banach algebras.     

Nonsmooth Mapping of Linear Control Systems

This paper deals with linear control systems of a special form. The main goal of the paper is to find the exact analytic solution of the time-optimal control problem for an arbitrary linear control system with constant coefficients using the analytic solution of this problem for the canonical system. For this aim, we construct a certain nonsmooth mapping between the 0-controllability sets of the given systems. In other words, by means of this mapping, we investigate the equivalence of the systems with the same qualitative behavior in a neighborhood of the stationary point.     

半开口管道中的氢/空气火焰加速和压力发展过程

本文研究了氢／空气预混火焰在半开口管道中的火焰加速现象和压力发展过程．结果表明,重复布置的障碍物对火焰速度和压力提升产生显著的影响．火焰传播状态随着氢气当量比的变化而发生改变,在氢气当量比约为０．３４时,火焰速度出现第一次跃变;随着氢气当量比进一步提高,火焰速度发生第二次跃变,即由爆燃转为爆轰．发生爆轰时氢气当量比的范围随着阻塞比的不同而发生变化．     

Congruence Kernels in Weakly Regular Varieties

We generalize the concept of deductive system of Hilbert algebras for the general case of algebras in weakly regular variety and we show that congruence kernels of these algebras are just deductive systems. This concept enables us to describe congruence classes in algebras of weakly regular varieties.AMS Subject Classification (1991): 08A30 08B05     

Effects of temperature and moisture on the mechanical properties of polyester resin in tension

The effect of environment on the physical and mechanical properties of composite materials in some cases is determined by the environmental sensitivity of the binder. The results of experimental investigation of the deformability and strength of polyester resin, widely used as a binder in composites, upon the action of stationary and quasi-stationary loads, temperatures, and moisture are presented. The ranges of acceptable values of these services factors are determined. The elastic modulus and tensile strength of the material are obtained from quasi-static tests. The viscoelastic behavior of the resin is investigated in creep tests. From the results of a short-term experiment with stepwise loading up to failure, it is found that the creep of specimens with a moisture content of 0.14% can be described by a linear viscoelastic model for stresses up to 20 MPa (two thirds of the strength). The action of single loading impulses is summarized according to the Boltzmann superposition principle. The temperature and absorbed moisture are considered as factors accelerating the relaxation processes in the material. The creep activation under the action of these factors is described using the methods of time-temperature and time-moisture equivalence. The results of short-term creep tests allow us to determine the relaxation characteristics of the material in stationary conditions. The long-term creep under close-to-service conditions is predicted using these data and quite good agreement with the control test is obtained. The sensitivity of the material characteristics (strength, elastic modulus, and creep strain) to the action of temperature and moisture is estimated. The creep strain is most sensitive to the action of environmental factors. For a fully saturated material (moisture content 1.64 wt.%), after one hour creep, this strain four times exceeds that of a dry one. The same growth in deformability is caused by an 18°C increase in temperature. A quantitative comparison of the characteristics of polyester and epoxy resins allows us to choose the binder for composites and to estimate the expected environmental effect. Presented at the 11th International Conference on Mechanics of Composite Materials (Riga, June 11–15, 2000). Translated from Mekhanika Kompozitnykh Materialov, Vol. 36, No. 3, pp. 395–406, May–June, 2000.     

Equivalence for varieties in general and for $ {\cal BOOL} $ in particular

The varieties equivalent to a given variety are characterized in a purely categorical way. In fact they are described as the models of those Lawvere theories which are Morita equivalent to the Lawvere theory of which therefore are characterized first. Along this way the conceptual meanings of the n-th matrix power construction of a variety and McKenzie's σ-modification of classes of algebras [22] become transparent. Besides other applications not only the well known equivalences between the varieties of Post algebras of fixed orders m and the variety of Boolean algebras are obtained; moreover it can be shown that the varieties are the only varieties equivalent to . The results then are generalized to quasivarieties and more general classes of algebras. Received November 4, 1998; accepted in final form September 15, 1999.     

聚芳醚酮类聚合物晶体结构醚酮等效性的研究

半结晶的聚芳醚酮类聚合物 ( PAEKs)因其性能优异而在机械、航天等高技术领域中得到广泛应用 .有关其晶体结构的研究亦有许多文献报道[1～ 11] ,而醚基与酮基在晶体结构方面是否等效一直存在争议 .虽然醚酮等效性的观点已被广泛接受 [4～ 8] ,但对于聚合物主链中含联苯基团的 PAEKs的醚酮等效性的研究则复杂得多 .文献 [1 ]报道醚酮等效性在主链含有联苯基团时不再成立 .本文首次发现醚酮等效性在主链含有联苯基团时在适当条件下仍可成立 ,并对聚芳醚酮类聚合物晶体结构的醚酮等效性问题进行了系统阐述 .1　实验部分　　样品联苯聚醚酮 …     

A graphical characterization of the largest chain graphs

The paper presents a graphical characterization of the largest chain graphs which serve as unique representatives of classes of Markov equivalent chain graphs. The characterization is a basis for an algorithm constructing, for a given chain graph, the largest chain graph equivalent to it. The algorithm was used to generate a catalog of the largest chain graphs with at most five vertices. Every item of the catalog contains the largest chain graph of a class of Markov equivalent chain graphs and an economical record of the induced independency model.