Wavelet-based deconvolution of ultrasonic signals in nondestructive evaluation

INTRODUCTION Deconvolution of ultrasonic signals is defined as the solution of the inverse problem of convolving an input signal, known as the system function h(n), with a medium reflectivity function x(n) and can be rep- resented by y(n)=h(n)*x(n) η(n), (1) where y(n) is the measured signal, * denotes the convolution operation and η(n) is the additive noise. Recovering x(n) from the observation y(n) leads to improving the appearance and the axial resolution of the RF-signals by removin…     

数学问题二例

1.The triangle inequality guarantees that the sum of the lengthsof two side of a triangle is greater than the length of the third.As aconsequence,if x and y are the legs of a right triangle,with x≤y,andz is the hypotenuse,then x+y>z,so x>z-y.Under what circum-stances will x>2(z-y)be true?     

Homogenization of a nonlinear degenerate parabolic equation

1 Introduction a Let T > 0 and Ω be a bounded open set of R n with Lipschitz boundary ? Ω and let ? Ω = Γ 1 ∪ Γ2 with 1 H n? ( Γ1) > 0, we consider the homogenization of the mixed boundary value problem of the following equation set: 1 2 0 ( ) div ( , , , ) ( , ) ( , ) in (0, ), ( , , , ) 0 on (0, ), on (0, ), ( ,0) in , t b u a x t u u g xu f x t T a x tu u v T u h T u x u ε ε ε ε ε ε ε ε ε ε ε Ω ε εΓ Γ Ω ??? ? ? ? = ?? × ??? ? = × ? ??? = =× ?? (1) where v is the…     

大偶数表为两个素数之和（下）

In the paper: the representation of large even integer as a sum of two primes is proved to be right independently by each of W-progression ∑∞n=1(1)/((n+1)(n-1)!)of the discovery and the prime theorem. It is induced as two following problems which are solved for getting results of ration: Is there a function of f(2n) to be only dependent upon 2n or not? And it can express a number of group of prime solutions on representation of even integer as a sum of two primes. In one－dimensional space, the prime theorem is led into odd sequence integer to find P(G)～(2 )/(log n).P(G) is regarded as a data handling tool for setting a mathematical model of random sampling, get: P2n(1，1)n＞22n-P2=P1=f(2n)～(2nlogn/2)/(log2nlog2n)(2n→∞). The prime theorem π(x) is generalized to the two-dimensional space: π(x,y). A mathematical model of average values is set up by π(x,y), get: P2n(1，1)2n＞22n=P1+P2=f(2n)2～(2n)/(log22n)(2n→∞). But for expressing a number of group of prime solutions of even integer，the laws of values of principal steps of the two different functions f(2n) and f(2n)2 are unanimous. Thus, the proof of different ways lead to the same result and determines a forceful declaration: Goldbach’s conjecture is proved to be a right theorem.     

THE GENERATING THEORY OF THE FLUTES''''PROFILE OF SPECIAL REVOLVING TOOLS WITH CONSTANT-SPIRAL-ANGLED EDGES

The manafacturing theory proposed in this paper is composed of the se-lection of the machining type(motions and adjustments)and the determination of thefunctions of motion parameters.The paper shows that the special revolving tools withconstant spiral angled egdes can be ground in the[x y (?)]or[x y z (?)]systembased on the conjugate theory and differential geometry.The functions of motion pa-rameters in these two systems are deduced.     

Inspiring Questions from the Sea of Examinations(题海拾贝)

1 If x,y,and z are.positive intergers,howmany integers are between xy(z-1) and xyz?已知 x,y,z 是三个正整数,问在 yx(z-1)和xyz 之间存在多少个整数.Solution:xy-1.The number of integers between xy(z-1) and xyzmay be found by finding the difference between the twoproducts and subtracting 1.Thus this difference can be     

03年加拿大数学奥林匹克试题及解答

1.Consider a standard twelve-hour Clock whosehour and minute hands move continuously.Let m be aninteger,with 1≤m≤720.At precisely m minutesafter 12:00,the angle made by the hour hand andminute hand is exactly 1°.Determine all possible valuesof m.2.Find the last three digits of the number2003 2002 2001。3.Find all real positive solutions(if any)tOx3 y3 z3=x y z,andx2 y2 z2=xyz.     

Longest Paths and Cycles in Connected Claw-Free Graphs

A graph is called claw-free if it does not contain a claw as its induced subgraph. In this paper, we prove the following results : 1 ) If G is a 2-connected claw-free graph on n vertices, then for any vertex υ and any two distinct vertices x and y in V(G) - |υ| , G has a path containing v and all neighbors of v and connecting x and y;2) Let C be the longest cycle in a 3-connected claw-free graph G and H a component of G - C,and if H is connected but not 2-connected, then there exist nonadjacent vertices u and v in H such that |V(C)| ≥3(d(u) d(u)) -2.     

图的符号全划分数

Let G = （V, E） be a graph, and let f ： V →{-1, 1} be a two-valued function. If ∑x∈N（v） f（x） ≥ 1 for each v ∈ V, where N（v） is the open neighborhood of v, then f is a signed total dominating function on G. A set {fl, f2,… fd} of signed d total dominating functions on G with the property that ∑i=1^d fi（x） ≤ 1 for each x ∈ V, is called a signed total dominating family （of functions） on G. The maximum number of functions in a signed total dominating family on G is the signed total domatic number on G, denoted by dt^s（G）. The properties of the signed total domatic number dt^s（G） are studied in this paper. In particular, we give the sharp bounds of the signed total domatic number of regular graphs, complete bipartite graphs and complete graphs.     

Viscosity approximation methods with weakly contractive mappings for nonexpansive mappings

Let K be a closed convex subset of a real reflexive Banach space E, T:K→K be a nonexpansive mapping, and f:K→K be a fixed weakly contractive (may not be contractive) mapping. Then for any t∈(0, 1), let xt∈K be the unique fixed point of the weak contraction x tf(x) (1?t)Tx. If T has a fixed point and E admits a weakly sequentially continuous duality mapping from E to E*, then it is shown that {xt} converges to a fixed point of T as t→0. The results presented here improve and generalize the cor- responding results in (Xu, 2004).     

On the Ruled surfaces in Minkowski 3-space R1^3

INTRODUCTIONLet ú3={(x1,x2,x3)|x1,x2,x3∈ú} be a 3D vector space, x=(x1,x2,x3) and y=(y1,y2,y3) be two vectors in ú3. The pseudo scalar product of x and y is defined by     

Influence of baffle position on liquid sloshing during braking and turning of a tank truck

The influence of baffle position on liquid sloshing during the braking and turning of a tank truck was studied using a volume of fluid (VOF) model. The forces,their positions and weight distribution during braking and the forces and rolling moment during turning were calculated. The reliability of the calculation method was validated by comparisons with experimental results. The results showed that during braking,liquid splashes in the tank and the maximum forces and G (the ratio of weight acting on the front axle to the rear axle) are large when A (the ratio of the arch area above the baffle to the area of cross section)≤0.1. When A≥0.2,as the position of the baffle is lowered,the maximum of Fx (the force in direction x) first decreases then increases,and the maximum of Fy (the force in direction y) and G increase. During turning,liquid splashes in the tank and the maximum forces and M (the rolling moment) are large when D (the ratio of the arch area above the baffle to the area of cross section)≤0.2. When D≥0.3,as the position of the baffle is lowered,the maximums of Fy,Fz (the force in direction z) and M increase.     

A rigidity theorem for submanifolds in S^n＋p with constant scalar curvature

Let M‘ be a closed submanifold isometrically immersed in a unit sphere S^n p. Denote by R, H and S, the normalized scalar curvature, the mean curvature, and the square of the length of the second fundamental form of M‘, respectively. Suppose R is constant and ≥1. We study the pinching problem on S and prove a rigidity theorem for M‘ immersed in S^n p with parallel normalized mean curvature vector field. When n≥8 or, n=7 and p≤2, the pinching constant is best.     

Normal families and shared values of meromorphic functions

We studied the normality conditions in families of meromorphic functions, improved the results of Fang and Zalcman [Fang ML, Zalcman L, Normal families and shared values of meromorphic functions, Computational Methods and Function Theory, 2001, 1 (1): 289-299], and generalized two new normality criterions. Let F be a family of meromorphic functions in a domain D, a a non-zero finite complex number, B a positive real number, and k and m two positive integers satisfying m>2k 4. If every function denoted by f belonging to F has only zeros with multiplicity at least k and satisfies f m(z)f (k)(z)=a??f (k)(z)?≤B or f m(z)f (k)(z)=a??f (z)?≥B, then F is normal in D.     

Generalized Derivations in Prime Rings

Let R be a ring, a ,b ∈ R, ( D , α ) and (G , β ) be two generalized derivations of R . It is proved that if aD ( x ) = G ( x )b for all x ∈ R, then one of the following possibilities holds: (i) If either a or b is contained in C , then α = β= 0 and there exist p , q ∈ Qr ( RC) such that D ( x )= px and G ( x )= qx for all x ∈ R;(ii) If both a and b are contained in C , then either a = b= 0 or D and G are C-linearly dependent;(iii) If neither a nor b is contained in C , then there exist p , q ∈ Qr ( RC) and w ∈ Qr ( R) such that α ( x ) = [ q ,x] and β ( x ) = [ x ,p] for all x ∈ R, whence D ( x )= wx-xq and G ( x )= xp + avx with v ∈ C and aw-pb= 0.     

一些数字和公式的读法(英文)

31% thirty one percent 30.7°thirty point seven degrees0.631 nought point six three one +312 plus three and a half-514 minus five and a quarter 1xone over xy2 y squared k3 k cubed3a4 three a to the foura5茁2 alpha to the five over beta squaredx摇姨root x y3姨 the cube root of yz4姨the fourth root of z1x摇姨one over root x 1xnone over x to the n r=Rnlittle r equals big R over nxX+yY=1little x times big X plus little y times big Y equals onexX+yY=zZlittle x …     

相似形

基础篇课时一比例线段诊断练习一、填空题1.已知:x2=y3=m5=n7,则y∶(x+m+n)=.2.已知:x∶y∶z=2∶3∶5,则3x+4y-2zx-y+3z=.3.若x+y2x=45,则xy=.4.若ab=cd,且a、d的比例中项为10cm,则b、c的比例中项是.二、选择题1.若2x-y=0,则x-yx的值为()(A)22.(B)2.(C)2-1.(D)1-2.2.如果a∶b=3∶2,且b是a和c的比例中项,那么b∶c等于()(A)4∶3.(B)3∶2.(C)2∶3.(D)3∶4.3.已知点M将线段AB黄金分割(AM>BM),则下列各式中不正确的关系是()(A)AM∶BM=AB∶AM.(B)AM=5-12AB.(C)AM≈0.618AB.(D)BM=5-12AB.三、解答题1.已知:a-bb-c=ac,求证:ba+bc=2.…     

芬兰五所大学入学考试数学试题

1.Find the area bounded by the curves y2 =4 x and y=x.2 .Solve the inequality x+ 4 >2 x+ 2 .3.The cross section of a wooden beam is a rectangle.L et the height of the cross section be x and the width y.The strength of the beam is proportional to yx2 .Find the ratio of the cross sectional height and width forthe strongest possible beam cut from a log with a circular cross section of area A.4 .Two circles,one inside the other,touch at the point A.The radius of the bigger circle is less than th…     

A note on equicontinuous maps of graph space

1 Introduction 1 Let X as a compact metric space with the metric d and f :X → Xas a continuous map. For every nonnegative integer n , define f ninductively by f n = f ? f n?1, with f 0as the identity map on X . If there is a positive integer n such that f n( x )= x, the point x of X is called the periodic point of f and the least n is called the periodic point of x . A periodic point is called a fixed point. Denote the fixed points set and the periodic points set of f respectively by F ( f…     

On some difference sequence spaces defined by a sequence of Orlicz functions

INTRODUCTION Let w be the set of all sequences of real or com- plex numbers and R∞, c and c0 be the sequence spaces of bounded, convergent and null sequences x=(xk), respectively. A sequence x∈R∞ is said to be almost convergent (Lorentz, 1948) if all Banach limits of x coincide. Lorentz (1948) proved that 1 c? = ??? x =( xk ) :linm 1n ∑kn= xk s exists, uniformly in s???. Maddox (1967; 1978) has defined x to be strongly almost convergent to a number L if 1 linm 1n ∑k n= xk s? L=0,…