附录：外文翻译
5.1Introduction
Cylindrical shells are used innuclear,fossil and petrochemical industries. They are also used in heat exchangers of the shell and tube type.Generally.These vessels are easy to fabricate and install and economical to maintain. The design procedures in pressure vessel codes for cylindrical shells are mostly based on linear elastic assumption,occasionally allowing for limited inelastic behavior over a localized region.The shell thickness is the major design parameter and is usually controlledby internal pressure and sometimes by external pressure which can produce buckling.Applied loads are also important in controlling thickness and so are the disconti-nuity and thermal stresses.The basic thicknesses of cylindrical shells are Based on simpli?ed stress analysis and allowable stress for the material of construction.There are some variations of the basic equations in various design codes.Some of the equations are based on thick-wall Lame equations.In this chapter such equations will be discussed.Also we shall discuss the case of cylindrical shells under external pressure where there is a propensity of buckling or collapse.
5.2 Thin-shell equations
A shell is a curved plate-type structure.We shall limit our discussion to Shells of revolutions.Referring to Figure5.1 this is denoted by anangle ?,The meridional radius r1 and the conical radius r2,from the center line.The horizontal radius when the axis is vertical is r. If the shell thickness is t,with z being the coordinate across the thickness,following the convention of Flugge, We have the following stress resultants:
?-+
=
2
2
1 1) (
t
t
dz r
z
r
N
θ
θ
σ(5.1)
?-+
=
2
2
2 2) (
t
t
dz r
z
r
N
φ
φ
σ(5.2)
?-+
=
2
2
2 2) (
t
t
dz r
z
r
N
θφ
θφ
σ(5.3)
Figure 5.1 Thin shell of revolution .
?-+=2
21
1)(
t
t
dz r z r N θφφθσ (5.4) These stress resultants are assumed to be due only to an internal pressure, p,acting in the direction of r. For membrane shells where the Effects of bending can be ignored,all the moments are zero and further development leads to
θφφθN N =
The following equations result from considering force equilibrium along with the additional requirement of rotational symmetry:
0cos )
(1=-φφθφN r d rN d (5.6)
φφN r r pr N 122-
= (5.7) Noting that φsin 2r r = ,we have,by solving Eqs.(5.6)and(5.7),
2
2pr N =φ (5.8) )2(2122r r pr N -=
φ (5.9) The above two equations are the results for a general shell of revolution. Two speci?c cases result:
1. For a spherical shellof radius R, r1= r2 =R,which gives
2
pR N N ==θφ (5.10) 2. For a cylindrical pressure vessel of radius R,we have r1 =∞; r2 = R,which gives
2
pR N =φ (5.11) pR N =θ (5.12) This gives the hoop stress
t
pR t N hoop ==
=θφσσ (5.13) and the longitudinal stress t
pR t N long 2===θφσσ (5.14) These results will be shown to be identical to the results that follow. Let us consider a long thin cylindrical shell of radius R and thickness t, subject to an internal pressure p.By thin shell we mean the ones having the ratio R/t typically greater than about10.If the ends of the cylindrical shell are closed,there will be stresses in the hoop as well as the axial (longitudinal) directions.
A section of such a shell is shown in Figure5.2. The hoop(circumfer-ential)stress, hoop σand the longitudinal stress, long σ are indicated in the ?gure.The shell is assumed to be long and thin resulting in hoop σand long σto be uniform through the thickness.Therefore in this case hoop σand long σ are also referred to as membrane stress(there are no bending stresses associated with this type of loading).
Considering equilibrium across the cut section,we have,
tL R pL hoop σ2)2(=
Figure 5.2 Thin cylindrical shell. which gives
t
pR hoop =σ (5.15) Considering a cross-section of the shell perpendicular to its axis,we have
)2(2Rt R p long πσπ= Which gives
t pR hoop 2=
σ （5.16 5.3 Thick-shell equations
For R/t ratios typically less than 10,Eqs.(5.15) and (5.16) tend not to be accurate,and thick-shell equations have to be used. Consider a thick cylindrical shell of inside radius Ri and outside radius Ro subjected to an internal pressure p as shown in Figure5.3 .The stress function for this case(refer to AppendixI)is given as a Function of radius r as
2ln Br r A +=Φ (5.17)
Figure 5.3 Thick cylindrical shell .
with A and B to be determined by the boundary conditions. If we indicate the radial stress as rad o and the hoop and longitudinal Stress as indicated previously by hoop σand long σ,we have
B r A dr d r o rad 212+=Φ=
(5.18) B r
A dr d r o hoop 212+-=Φ= (5.19) The constants A and
B are determined from the following boundary conditions:
p rad -=σ at i R r =
0=rad σ at o R r = (5.20) Substituting(5.20)into(5.18)and(5.19),we have
)(22
22i o o
i R R R R A --= )(2222i o i R R p
R B -= (5.21)
Denoting the ratio of the outside to inside radii as m,so that m =Ro/Ri, We obtain theradial and hoop stresses
]1[122
2r
R m p o rad --=σ (5.22) ]1[1222r R m p o hoop
+-=σ (5.23) Figure5.4 shows the radial and hoop stress distributions.
The longitudinal stress,long σ is determined by considering the Equilibrium of forces across a plane normal to the axis of the shell,which gives
)(2
22i o long i R R R p -=πσπ (5.24)
This is of course based on the assumption that the longitudinal stress is a Form of membrane stress in that there is no variation across the thickness of The shell.Thus we have
Figure 5.4 Hoop and radial stress distribution .
)
1()(2222-=--=m p R R pR i o i
long σ (5.25) It should be noted however that the solutions indicated by Eqs.(5.22), (5.23),and(5.25) are valid for regions remote from discontinuities.
5.4 Approximate equations
For a moderately thick shell employing thin-shell theory and using the Mean radius Rm we get the expression of the hoop stress, hoop σ,as
t
t R p t pR i m hoop )2/(+=-=σ (5.26) Equating the hoop stress, hoop σ,to the code-allowable design stress, m S , We have
p
S pR t m i 5.0-= (5.27) Rewriting Eq.(5.27) in terms of the outside radius, o R we have,
t
t R p t pR o m hoop )2/(-=-=σ (5.28) Once again equating the hoop stress to the code-allowable design stress, S,we have
p
S pR t m 5.00+= (5.29) The equations in the ASME Boiler and Pressure Vessel Code are based On equating the maximum membrane stress to the allowable stress Corrected for weld joint ef?ciency.The allowable stress, m S ,is replaced by The term SE (to be explained later).In ASME Boiler and Pressure Vessel
Code,SectionVIII Division1, The Eqs .(5.27) and (5.29) are modi?ed as:
p
SE pR t 5.0-= (5.30) p
SE pR t 5.0+= (5.31) In ASME Boiler and Pressure Vessel Code SectionIII,Division1, the equationsusedare
p
SE pR t 6.0-= (5.32) p SE pR t 4.0+=
(5.33) In Eqs .(5.30)and (5.32), R stands for the inside radius, i R ,whereas in Eqs.(5.31) and (5.33) it stands for the outside radius, o R .In both of the above equations, S is the allowable stress and E is the joint ef?ciency.This joint ef?ciency is employed because cylindrical shells are often fabricated by welding.The values of E depend on the type of radio graphic examination performed at various welded seams of the shell.
5.5Buckling of cylindrical shells
Consider a long,thin cylindrical shell of mean diameter D and wall thickness t subjected to an external pressure P.The cylinder is in a stable con?guration as long as it remains circular in shape.If there is an initial ellipticity,the cylinder will be in an unstable condition and will eventually buckle.
If the cylinder is suf?ciently long,the end effects may be neglected and The problem may be considered as two-dimensional. Summing up the forces in the radial direction,we have
0)(22)(=--++++Pds V ds ds
dv V d N d ds dS dN N θθ or
0=-+Pds ds ds
dv Nd θ or
)2/(,0D R PRd ds ds
dv Nd ==-+θθ 0=--R
N dS dV P Summation of forces in the tangential direction(see Figure5.5) gives -02
2)()(=+++++θθd v d ds ds dv V N ds dS dN N 0=+-θvd ds ds
dN 0=-ds
dN R V
Figure 5.5 Equilibrium of a shell element.
With ds dM
V =,we have
ds dM
R ds dN 1
= Assuming deviation from circular shape to be small,we have
C R M
N +=
Where C is a constant
When
2D
R =
0==V M
2D
P N = Therefore
2D
P R M
N +=
022=--R N
s d M d P
01
2222=---R D P R M s d M d P
0)21(22
22=-++D R D P R M s d M d For a curved shell:
0)21()1(1223=--=D
R v Eh M 0))1(61(3
2222=-++Eh PD v R M s d M d with 2D
R ?
0))1(61(32222=-++M Eh PD
v R s d M
d With ))
1(64(32
22Eh v PD D k -+=
0222=+M k s d M
d
ks C ks C M cos sin 21+=
ks k C ks k C ds dM
cos sin 21+=
0=ds dM
at 0=s
0=ds dM at 4D
s π=
0)4sin(=D
k π
ππn D
k =)4(
n kD 4=
))
1(64(3222Eh v PD D k -+=
)14(4)
1(62232-=-n D Eh v D P cr With a minimum value of n=1,we get
32)()1(2d t
v E
P cr -=
(5.34)
For cylinder with shorter lengths,where the ends are free to expand Axially and rotate with the restriction of expanding radially,thecritical Pressure is given by
??????
??????+-+????????????+--+--=)41)(1(1)(24112)1()()1(3222222222222320D L n n D t E D L n v n n d t v E P cr
ππ When D
l is large: )1()()1(322320--=n d
t v E P cr (5.35) So that it becomes identical to the buckling pressure inEq.(5.34)for n= 2. In the ASME code,the critical pressure is calculated for two situations, Involving the ratio of the outside diameter to the thickness(Do/t) 1.10≥t
D o 2.
10 5.6 Discontinuity stresses in pressure vessels Let us take the special case of discontinuity at a juncture between a cylindrical vessel and ahemispherical head subjected to internal pressure p. For simplicity let us assume the spherical head and the cylindrical shell are Of the same thickness.If the mean radius and thethickness of the shell are Denoted by Rm and t respectively,then the hoop and the longitudinal Stresses in the cylindrica lshell are given by: t pR m hoop c =σ (5.36) t pR m long c 2=σ (5.37) The hoop and the longitudinal stresses in the spherical shell are given by: t pR m hoop s 2=σ (5.38) t pR m long s 2= σ (5.39) The radial growth or dilation of the cylindrical shell under internal pressure p is given by )2(22 v Et pR m r c -=δ (5.40) That of the spherical region is given by )1(22 v Et pR m r s -=δ (5.41) Where v is the Poisson’s ratio. If the spherical and the cylindrical portions were separated,the Difference in the radial growth would be Et pR m r s r c r 22 =-=δδδ (5.42) In the actual vessel the hemispherical head and the cylindrical shell are Kept in place by shear force, V and moment M per unit circumference. These discontinuity forces produce local bending stresses in the adjacent Portions of the vessel.The de?ection and the slope induced at the edges of The cylindrical and spherical portions by the force V are equal.The Continuity at the juncture will bes atis?ed if M equals zero and V is such That it produces a de?ection of δ/2. Applying the results from semi-in?nite beam on an elastic foundation Due to M and V , And substituting the spring rate of the foundation by 2 m R Et/ ))sin()(cos(2)cos(2222x x e Et R M x e Et R V x m x m βββββδββ--=-- (5.43) where β is the attenuation factor,given by 4 222)1(3t R v m -=β (5.44) We have with 2/δδ= and M=0.at x=0 Et R V m 222βδ = (5.45) Substituting the value of δ from Eq.(5.45)we have β8p V = (5.46) The longitudinal stress and the hoop stress distribution in the cylindrical region is then given by )sin(86222x e p t t pR x m long c ββσβ-±= (5.47) )sin(43)cos(422x e t vp x e t pR t pR x x m m hoop c ββ βσββ--±-= (5.48) Using numerical values as, p= 2MPa, Rm = 1m, t = 25mm,and Poisson’sratio, v =0.3,we have from Eq.(5.44), β = 0.008127/mm and the Longitudinal and the hoop stresses become )sin(3640x e x long c βσβ-±=Mpa (5.49) )sin(9.10)cos(2080x e x e x x hoop c ββσββ--±-=Mpa (5.50) In Eq .(5.49) the ?rst quantity –the membrane longitudinal stress –is a constant (equal to 40MPa) along the length of the vessel,while the second quantity –the bending stress –varies along the length.In Eq.(5.50) the membrane hoop stress (equal to 80MPa) stays constant along the length, while the direct compression stress due to shortening of the radius and the bending stress varies along the length of the vessel. 1.Find the thickness of a cylindrical shell 2m in diameter if it is required to contain an internal pressure of 7MPa.The allowable stress in the material is140MPa. 2.A thick cylindrical shell of 1.2m inside diameter and 1.5m outside diameter is subjected to an internal pressure of 35MPa.Determine the following: a.Magnitude and location of the maximum hoop stress b.Magnitude of the maximum radial stress and its location c.Average hoop stress 3.A thick cylinder has an inside diameter of 300mm and an outside Diameter of 450mm.If the allowable stress is175MPa,what is the maximum internal pressure that can be applied? 4.A cylinder has an inside radius of 1.8m and is subjected to an Internal pressure of 0.35 MPa.What is th required thickness if the Allowable stress is105 MPa? 5.For problem 4,what is the required thickness if thick cylinder equations were used? https://www.doczj.com/doc/275309856.html,ing ASME Boiler and Pressure Vessel Code equations,determine the thickness of a cast-iron pressure vessel subjected to an internal pressure of 0.5 Mpa using a joint ef?ciency of 85 percent and a corrosion allowance of 1.5mm.The allowable stress (Sm)of the material is14MPa. 第五章 5.1简介 圆柱形容器主要用于核能，石油化工工业，它们也用于管壳式换热器。通常，这些容器制造、安装容易，维护经济。压力容器标准中圆柱形容器的设计程序主要是基于线性弹性假设，有时允许局部区域有限的非弹性行为。外壳厚度是主要设计参数，通常是由内部压力控制，有时是由产生屈曲的外部压力控制。添加载荷、不连续应力、热应力在控制厚度的过程中也很重要。圆柱形容器的基本厚度主要是基于简化应力分析和建筑物料的许用应力。在不同的设计标准中基本方程有一些变化。有一些方程是基于厚壳方程。在这一章节，这些理论将被讨论。另外，我们还将讨论圆柱形容器外压失稳在情形。 5.2薄壳方程 对于弯板型结构，我们只讨论旋转壳。参考图5.1，从中心，记为角?，经向半径记为r1和锥形半径记为r2当轴是垂直时水平半径为r。当沿Z坐标方向的壁厚为t，根据下面的草图，我们得到残余应力。 ?-+ = 2 2 1 1) ( t t dz r z r N θ θ σ(5.1) ?-+=2 2 2 2)( t t dz r z r N φφσ (5.2) ?-+=222 2)( t t dz r z r N θφθφσ (5.3) 图5.1：旋转壳 ?-+=2 21 1)( t t dz r z r N θφφθσ (5.4) 径向的残余应力由内压产生，对于膜壳，弯曲的影响可以忽略。所有的弯矩为零，进一步推得： θφφθN N = 由旋转对称产生的力的平衡导出下面的方程： 0cos )(1=-φφ θφN r d rN d (5.6) φφN r r pr N 1 22-= (5.7) 由于φsin 2r r =，我们解出(5.6)和(5.7)得： 2 2pr N =φ (5.8) )2(2122r r pr N -= φ (5.9) 以上两个方程是普通壳的旋转的结果。两个具体的例子： 1.对于球壳，半径为R 则 r1= r2 =R 得出： 2 pR N N ==θφ (5.10) 2.对于圆柱形压力容器，半径为R ， 则r1 =∞; r2 = R 得出： 2 pR N =φ (5.11) pR N =θ (5.12) 环向应力： t pR t N hoop == =θφσσ (5.13) 轴向应力 t pR t N long 2===θφσσ (5.14) 这些结果与下面的结果一致。考虑一细长圆柱壳的半径为R ，厚度为t ，受内压为p 。薄壳是指壳的半径和厚度R/t 之比大于10。如果圆柱壳的两端是封闭的，还受环向应力和纵向应力。壳的局部图如图5.1所示。环向应力hoop σ和纵向应力long σ如图所示。外壳被假定为细长所以hoop σ和long σ沿厚度方向分布均匀。因此，这种情况下的hoop σ和long σ也称薄膜应力（这种类型载荷不存在弯曲应力） 考虑切节的平衡，得出： tL R pL hoop σ2)2(= 图5.2：圆柱壳 得出： t pR hoop =σ (5.15) 考虑横截面的壳垂直于轴心，我们得出： )2(2Rt R p long πσπ= t pR hoop 2= σ （5.16） 5.3 厚壳理论 壳的半径和厚度R/t 之比小于10，式(5.15)和 式(5.16)将会不准确，这时将用到厚壳理论，厚壳圆柱形容器的内径为Ri ，外径为Ro ，受内压为p ，如图5.3这种情况下的应力函数（参阅附录I ）由半径r 的函数给出： 2ln Br r A +=Φ (5.17) 图5.3厚壳圆柱形容器 A 和 B 由边界条件决定。如果用rad o 表示径向应力、用hoop σ表示环向应力和用long σ表示纵向应力，我们得出： B r A dr d r o rad 212+=Φ= (5.18) B r A dr d r o hoop 212+-=Φ= (5.19) 常量A 和 B 由下面的边界条件决定： p rad -=σ at i R r = 0=rad σ at o R r = (5.20) 将式 (5.20) 代入式(5.18)和式(5.19)得出： )(22 22i o o i R R R R A --= )(2222i o i R R p R B -= (5.21) 外径和内径之比记为m ，则m =Ro/Ri 我们得出径向和周向应力 ]1[1222r R m p o rad --=σ (5.22) ]1[12 22r R m p o h o o p +-=σ (5.23) 图5.4显示出径向和周向应力的分布 纵向压力long σ垂直壳轴的面受力平衡得出： )(222i o long i R R R p -=πσπ (5.24) 假定纵向应力是薄膜应力的一种，而且壳的厚度没有变化。因此，得出： 图5.4径向和周向应力的分布 ) 1()(2222-=--=m p R R pR i o i long σ (5.25) 值得一提的是：由式(5.22)、 (5.23) 和(5.25)推出的结果在远离不连续性区域处有效。 对于中等厚壳，运用薄壳方程和平均半径Rm ，我们得出环向应力的方程。 t t R p t pR i m hoop )2/(+=-=σ (5.26) 等值的环向应力hoop σ，允许设计应力Sm ，得出： p S pR t m i 5.0-= (5.27) 将外径代入(5.27)式得： t t R p t pR o m hoop )2/(-=-=σ (5.28) 又等同的环向应力的允许设计应力S 得： p S pR t m 5.00+= (5.29) 这些方程在ASME 锅炉及压力容器标准中主要是基于等同最大薄膜应力的容许应力，根据焊接接头效率校正。许用应力Sm 用SE （稍后解释）替代，在ASME VIII -1锅炉及压力容器标准中，.(5.27) 式和(5.29)式修改为： p SE pR t 5.0-= (5.30) p SE pR t 5.0+= (5.31) 在ASME VIII -1锅炉及压力容器标准中，方程变为： p SE pR t 6.0-= (5.32) p SE pR t 4.0+= (5.33) 在(5.30) 式和(5.32)式中，Ri 代表内径，然而在(5.31)式和 (5.33)式中Ro 代表外径。在上面两个式子中，S 为许用应力，E 是接头效率。用接头效率是因为圆柱壳容器通常是用焊接制造的。E 的值取决于壳上采用的焊缝的种类。 5.5圆柱壳的屈曲 细长圆柱壳容器的中径为D ，厚度为t ，受外压为p ，只要它仍然是圆形，圆柱体是一个稳定的配置，如果最初的椭圆，柱体将工作在不稳定工况，最终将屈曲。 如果圆柱体足够长，端面的因素可以忽略，问题可以认为在二维平面内。 总结径向方向上的受力，得出： 0)(22)(=--++++Pds V ds ds dv V d N d ds dS dN N θθ 0=-+P d s ds ds dv Nd θ )2/(,0D R PRd ds ds dv Nd ==-+θθ 0=--R N dS dV P 总结切向方向上的受力（见图5.5），得出： -02 2)()(=+++++θθd v d ds ds dv V N ds dS dN N 0=+-θvd ds ds dN 0=-ds dN R V 图5.5壳单元的平衡 代入 ds dM V =,得 ds dM R ds dN 1= 假定圆形变形偏差可以忽略不计，得出： C R M N += 其中C 是一个常量 因为2D R =，0==V M ，2D P N = 所以： 2D P R M N += 022=--R N s d M d P 01 2222=---R D P R M s d M d P )21(2222=-++D R D P R M s d M d 对于弯曲壳体: 0)2 1 ()1(1223 =--=D R v Eh M 毕业设计外文资料翻译 题目POLISHING OF CERAMIC TILES 抛光瓷砖 学院材料科学与工程 专业复合材料与工程 班级复材0802 学生 学号20080103114 指导教师 二〇一二年三月二十八日 MATERIALS AND MANUFACTURING PROCESSES, 17(3), 401–413 (2002) POLISHING OF CERAMIC TILES C. Y. Wang,* X. Wei, and H. Yuan Institute of Manufacturing Technology, Guangdong University ofTechnology, Guangzhou 510090, P.R. China ABSTRACT Grinding and polishing are important steps in the production of decorative vitreous ceramic tiles. Different combinations of finishing wheels and polishing wheels are tested to optimize their selection. The results show that the surface glossiness depends not only on the surface quality before machining, but also on the characteristics of the ceramic tiles as well as the performance of grinding and polishing wheels. The performance of the polishing wheel is the key for a good final surface quality. The surface glossiness after finishing must be above 208 in order to get higher polishing quality because finishing will limit the maximum surface glossiness by polishing. The optimized combination of grinding and polishing wheels for all the steps will achieve shorter machining times and better surface quality. No obvious relationships are found between the hardness of ceramic tiles and surface quality or the wear of grinding wheels; therefore, the hardness of the ceramic tile cannot be used for evaluating its machinability. Key Words: Ceramic tiles; Grinding wheel; Polishing wheel 吉林化工学院理学院 毕业论文外文翻译English Title（Times New Roman ，三号） 学生学号：08810219 学生姓名：袁庚文 专业班级：信息与计算科学0802 指导教师：赵瑛 职称副教授 起止日期：2012.2.27～2012.3.14 吉林化工学院 Jilin Institute of Chemical Technology 1 外文翻译的基本内容 应选择与本课题密切相关的外文文献（学术期刊网上的），译成中文，与原文装订在一起并独立成册。在毕业答辩前，同论文一起上交。译文字数不应少于3000个汉字。 2 书写规范 2.1 外文翻译的正文格式 正文版心设置为：上边距：3.5厘米，下边距：2.5厘米，左边距：3.5厘米，右边距：2厘米，页眉：2.5厘米，页脚：2厘米。 中文部分正文选用模板中的样式所定义的“正文”，每段落首行缩进2字；或者手动设置成每段落首行缩进2字，字体：宋体，字号：小四，行距：多倍行距1.3，间距：前段、后段均为0行。 这部分工作模板中已经自动设置为缺省值。 2.2标题格式 特别注意：各级标题的具体形式可参照外文原文确定。 1．第一级标题（如：第1章绪论）选用模板中的样式所定义的“标题1”，居左；或者手动设置成字体：黑体，居左，字号：三号，1.5倍行距，段后11磅，段前为11磅。 2．第二级标题（如：1.2 摘要与关键词）选用模板中的样式所定义的“标题2”，居左；或者手动设置成字体：黑体，居左，字号：四号，1.5倍行距，段后为0，段前0.5行。 3．第三级标题（如：1.2.1 摘要）选用模板中的样式所定义的“标题3”，居左；或者手动设置成字体：黑体，居左，字号：小四，1.5倍行距，段后为0，段前0.5行。 标题和后面文字之间空一格（半角）。 3 图表及公式等的格式说明 图表、公式、参考文献等的格式详见《吉林化工学院本科学生毕业设计说明书（论文）撰写规范及标准模版》中相关的说明。 Thermoelectric Properties of n -Type Bi 2Te 3/PbSe 0.5Te 0.5Segmented Thermoelectric Material SEJIN YOON,1JUN-YOUNG CHO,1HYUN KOO,1SUNG-HWAN BAE,1SEUNGHYUN AHN,1GWI RANG KIM,1JIN-SANG KIM,2and CHAN PARK 1,3,4 1.—Department of Materials Science and Engineering,Seoul National University,Daehak-dong,Gwanak-gu,Seoul,Republic of Korea. 2.—Electronic Materials Research Center,Korea Institute of Science and Technology,Wolgok 2-dong,Seongbuk-gu,Seoul,Republic of Korea. 3.—Research Institute of Advanced Materials,Seoul National University,Daehak-dong,Gwanak-gu,Seoul,Republic of Korea. 4.—e-mail:pchan@snu.ac.kr To investigate the effects of segmentation of thermoelectric materials on performance levels,n -type segmented Bi 2Te 3/PbSe 0.5Te 0.5thermoelectric material was fabricated,and its output power was measured and compared with those of Bi 2Te 3and PbSe 0.5Te 0.5.The two materials were bonded by diffusion bonding with a diffusion layer that was $18l m thick.The electrical conductivity,Seebeck coef?cient,and power factor of the segmented Bi 2Te 3/PbSe 0.5Te 0.5sample were close to the average of the values for Bi 2Te 3and PbSe 0.5Te 0.5.The output power of Bi 2Te 3was higher than those of PbSe 0.5Te 0.5and the segmented sample for small D T (300K to 400K and 300K to 500K),but that of the segmented sample was higher than those of Bi 2Te 3and PbSe 0.5Te 0.5when D T exceeded 300K (300K to 600K and 300K to 700K).The output power of the segmented sample was about 15%and 73%higher than those of the Bi 2Te 3and PbSe 0.5Te 0.5samples,respectively,when D T was 400K (300K to 700K).The ef?ciency of thermoelectric materials for large temperature differences can be enhanced by segmenting materials with high performance in different temperature ranges. Key words:Thermoelectric material,segmented thermoelectric material, Bi 2Te 3,Pb(Se,Te),output power INTRODUCTION Many studies have focused on improving the energy conversion ef?ciency of thermoelectric materials for their potential use in power-generation and cooling systems.The ef?ciency of a thermoelectric material is characterized by its dimensionless ?gure of merit [zT =(S 2r T )/j ,where S is the Seebeck coef?cient,r is the electrical conductivity,and j denotes the thermal conductivity].1 The upper limit of the ef?ciency (g ?g c ??????????????? 1tzT p à1 =???????????????1tzT p t1àg c h i ,where g c =D T /T hot is the Carnot ef?ciency,and zT is the average zT over the temperature range)is determined by the temperature difference D T ,2,3which means that better energy conversion can be expected with the use of a larger D T .Most thermoelectric materials,how-ever,have high zT over a very limited temperature range,indicating that most thermoelectric materials cannot effectively utilize such a large D T .High ther-moelectric energy conversion ef?ciency can be obtained when a large D T can be used,which can only be realized by using a thermoelectric material with high zT value across a broad temperature range.Materials with large average zT values over a wide temperature range have to be used to convert large amounts of energy from a large D T .Connection of materials with high zT values in different tempera-ture ranges,forming a segmented thermoelectric (Received May 10,2013;accepted October 14,2013;published online November 27,2013) Journal of ELECTRONIC MATERIALS,Vol.43,No.2,2014 DOI:10.1007/s11664-013-2869-4ó2013TMS 414 Load and Ultimate Moment of Prestressed Concrete Action Under Overload-Cracking Load It has been shown that a variation in the external load acting on a prestressed beam results in a change in the location of the pressure line for beams in the elastic range.This is a fundamental principle of prestressed construction.In a normal prestressed beam,this shift in the location of the pressure line continues at a relatively uniform rate,as the external load is increased,to the point where cracks develop in the tension fiber.After the cracking load has been exceeded,the rate of movement in the pressure line decreases as additional load is applied,and a significant increase in the stress in the prestressing tendon and the resultant concrete force begins to take place.This change in the action of the internal moment continues until all movement of the pressure line ceases.The moment caused by loads that are applied thereafter is offset entirely by a corresponding and proportional change in the internal forces,just as in reinforced-concrete construction.This fact,that the load in the elastic range and the plastic range is carried by actions that are fundamentally different,is very significant and renders strength computations essential for all designs in order to ensure that adequate safety factors exist.This is true even though the stresses in the elastic range may conform to a recognized elastic design criterion. It should be noted that the load deflection curve is close to a straight line up to the cracking load and that the curve becomes progressively more curved as the load is increased above the cracking load.The curvature of the load-deflection curve for loads over the cracking load is due to the change in the basic internal resisting moment action that counteracts the applied loads,as described above,as well as to plastic strains that begin to take place in the steel and the concrete when stressed to high levels. In some structures it may be essential that the flexural members remain crack free even under significant overloads.This may be due to the structures’being exposed to exceptionally corrosive atmospheres during their useful life.In designing prestressed members to be used in special structures of this type,it may be necessary to compute the load that causes cracking of the tensile flange,in order to ensure that adequate safety against cracking is provided by the design.The computation of the moment that will cause cracking is also necessary to ensure compliance with some design criteria. Many tests have demonstrated that the load-deflection curves of prestressed beams are approximately linear up to and slightly in excess of the load that causes the first cracks in the tensile flange.(The linearity is a function of the rate at which the load is applied.)For this reason,normal elastic-design relationships can be used in computing the cracking load by simply determining the load that results in a net tensile stress in the tensile flange(prestress minus the effects of the applied loads)that is equal to the tensile strength of the concrete.It is customary to assume that the flexural tensile strength of the concrete is equal to the modulus of rupture of the 要求：选择一篇和自己论文或者自己专业相关的外文进行翻译，英文字符数在6000-7000字符（注：可以继续按原文的一部分）。排版格式按照下文 公司的核心竞争力 原文来源：The Core Competence of the Corporation, Research Report on Harvard Business Review,1990 至少有三种检验方法可以用来确定公司的核心竞争力。首先，核心竞争力能够为公司进入多个市场提供方便。举例来说，显示器系统方面的核心竞争力能够使一家公司涉足计算器、微型电视机、手提电脑显示屏以及汽车仪表盘等广泛的业务领域，这就是卡西欧公司进军手持式电视机市场不足为奇的原因。第二，核心竞争力应当对最终产品为客户带来的可感知价值有重大贡献。显然，本田公司的发动机专长满足了这个条件。 最后一点，核心竞争力应当是竞争对手难以模仿的。如果核心竞争力是各项技术和生产技能的复杂的融合，那么这项能力就难以被竞争对手模仿。竞争对手或许能够获得核心竞争力中的几种技术，但是要复制其内部协调与学习的整体模式却非常困难。在20世纪60年代初期，JVC决定致力于录像带技术方面的核心竞争力，这个核心竞争力就通过了我们上述的三项检验。20世纪70年代末美国的RCA公司决心开发以唱针为基础的视频转动式系统，这个项目则不能通过上述三项检验。 。。。。。。。。。。。 The Core Competence of the Corporation The Core Competence of the Corporation Research Report on Harvard Business Review,1990 The distinction we observed in the way NEC and GTE conceived of themselves a portfolio of competencies versus a portfolio of businesses was repeated across many industries. From 1980 to 1988, Canon grew by 264%, Honda by 200%. Compare that with Xerox and Chrysler. And if Western managers were once anxious about the low cost and high quality of Japanese imports, they are now overwhelmed by the pace at which Japanese rivals are inventing new markets, creating new products, and enhancing them. Canon has given us personal copiers; Honda has moved from motorcycles to four wheel off road buggies. Sony developed the 8mm camcorder, Yamaha, the digital piano. Komatsu developed an underwater remote controlled bulldozer, while Casio's latest gambit is a small screen color LCD television. Who would have anticipated the evolution of these vanguard markets? In more established markets, the Japanese challenge has been just as disquieting. Japanese companies are generating a blizzard of features and functional enhancements that bring technological sophistication to everyday products. Japanese car producers have been pioneering four wheel steering, four valve-per cylinder engines, in car navigation systems, and sophisticated 法学毕业论文参考文献精选 [1] 姜玉丹，苏静. 从BBS到开心网、人人网看大学生 网络行为方式的转变[J]. 中国林业教育. 2011（S1） [2] 方彩芬. 网络语言特点透析[J]. 宁波高等专科学校 学报. 2002（01） [3] W Schramm. Mass Communication[J]. Annual Review of Psychology . 1962 [4] 郑华清，黄崇珍. 从“杯具”看网络流行语的语言 变异[J]. 湖北经济学院学报（人文社会科学版）. 2011（01） [5] Beijing University Youth Research Center （Youth Research Center,Beijing University,Beijing,100871,China）. 高校BBS与SNS网站的比 较研究--以北京大学未名BBS和人人网为例[J]. 高校辅导员学刊. 2010（04） [6] 李力. 新媒体时代的网络舆情应对研究[D]. 南昌大 学 2014 [7] 华姐措. 藏族民间文化在大众传媒中的传播与发展 研究[D]. 西北民族大学 2014 [8] 王泉. 参与式文化背景下的大学生媒介素养教育[D]. 南京邮电大学 2014 [9] 邱婷婷. 微博名人头像真实性对消费者购买决策的 影响[D]. 浙江大学 2015 [10] 朱冬顺. 基于信任基础的虚拟社区内口碑再传播影响因素研究[D]. 浙江大学 2015 [11] 沈玉秋. 传播学视域下对《金枝》文化内涵的解读 [D]. 西北民族大学 2014 [12] 翟敬朋. 老人的社会功能与幸福感的关系研究[D]. 南京大学 2014 [13] 张晔. 虚拟社区中同妻群体生活适应问题的研究 [D]. 哈尔滨工业大学 2012 [14] 陆莹. 人人网中大学生自我呈现研究[D]. 哈尔滨工业大学 2010 [15] 李丽. 大学生网络购物的自我认同建构研究[D]. 哈尔滨工业大学 2010 [16] 于立华. 我国非传统社团社会功能的哲学思考[D]. 中国石油大学 2007 [17] 孟一. 微博的社会功能及其作用方式研究[D]. 广西师范学院 2012 [18] 郭修远. 学术新闻的功能与传播规范[D]. 湖南大学 2012 [19] 康晶晶. 浅析社会中的语言变异--以网络流行语为例[J]. 民营科技. 2010（06） [20] 陈原着.社会语言学[M]. 商务印书馆， 2000 [1] 周峰. 密闭微波辅助提取-HPLC测定中成药中黄芩苷及绿原酸的研究[D]. 北京化工大学 2009 本科毕业设计（外文翻译） 题目居住区交往空间规划与设计 院（系部）xxx学院 专业名称xx 年级班级xx 学生姓名xx 指导教师xx xx 年xx 月x 日 Planning and Design of Association Space of residential District Xia dong liang 【Abstract】:The association space refers to the indoor and outdoor space for communication between residents.The article presents an overall discussion of the necessity，hierarchy and functionality of association space,with a wish to create positive and healthy association atmosphere and stimulate good communication among residents so that the residential area can become a homeland full of love and harmony． 【Keyword】:residential area；association space；necessity；hierarchy；Functionality 【Foreword】：As the housing system reform and the rapid development of real estate, urban residential areas large urban settlements have emerged on the layout of residential buildings, public buildings, public green space, life and living facilities such as roads, to provide urban residents live in the community and The establishment, is an integral part of the city. Exchanges between the living room area residents is to communicate and exchange of indoor and outdoor space. At this stage, people's living standards greatly improved the living environment of continuous improvement district. Developers should not only focus on residential construction and the reasonable comfort, paying greater attention to the construction of residential environment. However, the current environment in the construction of residential areas, they are often the natural ecology of greening the environment is much more to consider, and the promotion of exchanges between the residents of the space environment to consider less, environmental construction can not meet the occupants of the psychological characteristics and needs. From the basic physiological needs gradually to meet the psychological and cultural fields of promoting a higher level, the residential area is not only the function of living, but also people's thinking and feelings of the local exchange. Therefore, the strengthening of exchanges between the residential areas of space construction, increase residential neighbourhood affinity, should be developed in the planning and construction of residential areas should also consider the issue. How to conduct exchanges between the residential areas of space planning and design, improve people's quality of life, the author of his own real estate development 毕业论文（设计）外文翻译 题目：中国上市公司偏好股权融资：非制度性因素 系部名称：经济管理系专业班级:会计082班 学生姓名：任民学号： 200880444228 指导教师：冯银波教师职称:讲师 年月日 译文： 中国上市公司偏好股权融资：非制度性因素 国际商业管理杂志 2009.10 摘要：本文把重点集中于中国上市公司的融资活动，运用西方融资理论，从非制度性因素方面，如融资成本、企业资产类型和质量、盈利能力、行业因素、股权结构因素、财务管理水平和社会文化，分析了中国上市公司倾向于股权融资的原因，并得出结论，股权融资偏好是上市公司根据中国融资环境的一种合理的选择。最后，针对公司的股权融资偏好提出了一些简明的建议。 关键词：股权融资，非制度性因素，融资成本 一、前言 中国上市公司偏好于股权融资，根据中国证券报的数据显示，1997年上市公司在资本市场的融资金额为95.87亿美元，其中股票融资的比例是72.5％，，在1998年和1999年比例分别为72.6％和72.3％，另一方面，债券融资的比例分别是17.8％，24.9％和25.1％。在这三年，股票融资的比例，在比中国发达的资本市场中却在下跌。以美国为例，当美国企业需要的资金在资本市场上，于股权融资相比他们宁愿选择债券融资。统计数据显示，从1970年到1985年，美日企业债券融资占了境外融资的91.7％，比股权融资高很多。阎达五等发现，大约中国3/4的上市公司偏好于股权融资。许多研究的学者认为，上市公司按以下顺序进行外部融资：第一个是股票基金，第二个是可转换债券，三是短期债务，最后一个是长期负债。许多研究人员通常分析我国上市公司偏好股权是由于我们国家的经济改革所带来的制度性因素。他们认为，上市公司的融资活动违背了西方古典融资理论只是因为那些制度性原因。例如，优序融资理论认为，当企业需要资金时，他们首先应该转向内部资金（折旧和留存收益），然后再进行债权融资，最后的选择是股票融资。在这篇文章中，笔者认为，这是因为具体的金融环境激活了企业的这种偏好，并结合了非制度性因素和西方金融理论，尝试解释股权融资偏好的原因。 The development of plastic mould China's industrial plastic moulds from the start to now, after more than half a century, there has been great development, mold levels have been greatly enhanced. Mould has been at large can produce 48-inch big-screen color TV Molded Case injection mold, 6.5 kg capacity washing machine full of plastic molds, as well as the overall car bumpers and dashboards, and other plastic mould precision plastic molds, the camera is capable of producing plastic mould , multi-cavity mold small modulus gear and molding mold. --Such as Tianjin and Yantai days Electrical Co., Ltd Polaris IK Co. manufactured multi-cavity mold VCD and DVD gear, the gear production of such size precision plastic parts, coaxial, beating requirements have reached a similar foreign the level of product, but also the application of the latest gear design software to correct contraction as a result of the molding profile error to the standard involute requirements. Production can only 0.08 mm thickness of a two-cavity mold and the air Cup difficulty of plastic doors and windows out of high modulus, and so on. Model cavity injection molding manufacturing accuracy of 0.02 to 0.05 mm, surface roughness Ra0.2 μ m, mold quality, and significantly increase life expectancy, non-hardening steel mould life up to 10~ 30 million, hardening steel form up to 50 ~ 10 million times, shorten the delivery time than before, but still higher than abroad,and the gap between a specific data table. Process, the multi-material plastic molding die, efficient multicolor injection mould, inserts exchange structure and core pulling Stripping the innovative design has also made great progress. Gas-assisted injection molding, the use of more mature technologies, such as Qingdao Hisense Co., Ltd., Tianjin factory communications and broadcasting companies, such as mold manufacturers succeeded in 29 ~ 34-inch TV thick-walled shell, as well as some parts on the use of gas-assisted mould technology Some manufacturers also use the C-MOLD gas-assisted software and achieved better results. Prescott, such as Shanghai, such as the new company will provide users with gas-assisted molding equipment and technology. Began promoting hot runner mold, and some plants use rate of more than 20 percent, the general heat-thermal hot runner, or device, a small number of units with the world's advanced level of rigorous hot runner-needle device, a small number of units with World advanced level of rigorous needle-hot runner mould. However, the use of hot runner overall rate of less than 10%, with overseas compared to 50 ~ 80%, the gap larger. In the manufacturing technology, CAD / CAM / CAE technology on the level of application of a new level to the enterprise for the production of household appliances representatives have introduced a considerable number of CAD / CAM systems, such as the United States EDS UG Ⅱ,复合材料与工程专业毕业设计外文文献翻译
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