采用多元弯曲组划分的线要素化简方法

线要素化简是制图综合中的重要研究内容和经典研究问题之一.针对当前基于弯曲的线化简方法中对连续弯曲取舍研究的不足,在分析线要素弯曲构成特点及取舍过程的基础上,提出一种采用多元弯曲组划分的线化简方法.首先基于目标比例尺下弯曲可视性划分多元弯曲组;为避免线要素化简过度,设计了合理的弯曲组内弯曲取舍方案,并从中选择整体位移最小的弯曲取舍方案化简多元弯曲组;最后重复化简过程,直到化简结果中不存在目标尺度下不可视的细小弯曲为止.通过对比实验,从视觉感受和量化分析的角度验证了该方法的有效性和适应性.

道路弯曲组共线与移位的协同处理方法

地图上道路符号化后的共线处理是解决道路符号空间冲突的方法之一。文中提出一种道路弯曲组共线和移位的协同处理方法,该方法利用道路的约束性三角网识别道路的空间冲突区域,提取空间冲突路段区域的骨架线,并计算相关弯曲的特征信息,然后把道路符号共线的几何计算方法和Snake移位模型相结合,协同解决道路符号共线和移位问题。该方法不仅能保证在给定的空间位置上道路符号共线,也能够保持道路形状特征。实验结果验证算法的有效性和实用性。

道路弯曲组共线与移位的协同处理方法

在地图自动编制中,有时计算机难以完成道路弯曲组共线与移位的协同处理的空间冲突问题,人们需要给出一套处理规则,让计算机批量的完成空间冲突产生后数据的分析。用Delaunay三角网判断地图综合后空间一致性的关系,利用经典Beam移位模型让计算机完成,空间冲突产生后数据的分析应用地图要素移位的制图评价规则分析数据处理的质量。应用实验说明了这种道路弯曲组共线与移位的协同处理方法的有效性和通用性。

采用三元弯曲组划分的线要素化简方法

当前基于弯曲的线要素化简在化简过程中对于连续小弯曲的化简处理有所欠缺。针对此提出了基于三元弯曲组的化简方法。该方法首先将连续的弯曲划分到各个弯曲三元组中;然后针对三元弯曲的不同组合类型采用不同的化简方式进行化简;最后设计循环化简判断规则,重复化简过程直到所有弯曲满足化简阈值,从而实现连续弯曲的间隔化简。实验表明,该方法能够有效地保持弯曲的形态特征以及不同化简阈值结果间的层次性。

高频层压弯曲木液压机组

河北省石家庄开发区纪元电气有限公司开发的高频层压弯曲木液压机组操作方便、加热快、能耗低、质量好、效率高、模具费用低等特点，已成为家具、乐器、鞋材、工艺品等等领域的加工弯曲木制品的首选设备之一。

Influence of microstructure and texture on formability of AZ31B magnesium alloy sheets

The effect of the repeated unidirectional bending （RUB） process and annealing on the formability of magnesium alloy sheets was investigated. The RUB process and annealing treatments produce two effects on microstructure： grain coarsening and weakening of the texture. The sheet that underwent RUB and was annealed at 300 ℃exhibits the best formability owing to the reduction of the （0002） basal texture intensity, which results in low yield strength, large fracture elongation, small Lankford value （r-value） and large strain hardening exponent （n-value）. Compared with the as-received sheet, the coarse-grain sheet produced by RUB and annealing at 400 ℃ exhibits lower tensile properties but higher formability. The phenomenon is because the deformation twin enhanced by grain coarsening can accommodate the strain of thickness.

浅谈铅酸蓄电池涂板

简要介绍了手工涂板的操作方法,分析了单面涂板机和双面涂板机的工作原理,采用双面涂板机涂板正面和反面均匀一致,反面没有露筋现象;而采用单面涂板机涂板反面露筋现象严重。采用双面涂板机涂板能够克服电池化成后极群组弯曲现象。

Microstructure and formability evolutions of AZ31 magnesium alloy sheets undergoing continuous bending process

Continuous bending (CB) process along rolling direction was performed to improve the formability of AZ31 magnesium alloy sheets. The microstructure and texture evolutions were characterized by optical microscopy (OM) and electronic backscatter diffraction (EBSD). The results reveal that the basal texture intensity of continuously bent and annealed (CBA) sample is drastically weakened. A large number of twins are induced on the concave surface by the 1st pass bending and the density of twins obviously declines during the 2nd pass bending owing to the occurrence of detwinning. Due to the asymmetric tension?compression strain states between the outer and inner regions during V-bending, twinning and detwinning are generated alternatively during the CB process. The Erichsen value is 5.2 mm which increases by 41% compared with that of as-received sample. This obvious improvement of formability can be attributed to the weakened basal texture, which leads to a smaller plastic strain ratio (r-value)together with a larger strain-hardening exponent (n-value).

Effects of pre-deformation mode and strain on creep aging bend-forming process of Al-Cu-Li alloy

The bending deformation method was adopted to characterize the creep deformation behavior of Al-Cu-Li alloy in the creep aging forming(CAF) process based on a series of CAF tests, and the evolution laws of its mechanical properties and microstructures under different pre-deformation conditions were studied. The results show that the bending creep strain characterization method can intuitively describe the creep variation. With the increase of the pre-deformation strain, the creep strain of the specimen firstly increases and then decreases. The increase of the pre-deformation strain can promote the course of aging precipitation, and improve the formed alloy’s tensile properties at room temperature, the Kahn tearing properties, and the fatigue propagation properties. Pre-rolled specimens produce a slightly weaker work hardening than pre-stretched specimens, but they also create a stronger aging-strengthening effect;thus the strength, toughness and damage performance can be improved to some extent. Among all the types of specimens, the specimen with 3% rolling after CAF treatment has the best comprehensive mechanical properties.

Flexural Behavior of FRP-Reinforced Concrete Composite Member

Concrete Filled FRP （Reinforced Polymeric Plastic） Tubes （CFFT） and Reinforced Concrete Filled FRP Tubes （RCFFT） are known to have the capability to enhance structural performance in terms of structural stability, ductility, as well as chemical resistance when compared with conventional concrete members. In this study, the authors evaluate the structural performance of the CFFT and the RCFFT through flexural tests for the purpose of applying the members as flexural ones. Moreover, the compressive behavior of the CFFT and the RCFFT members was investigated to examine their confinement effects. Based on the experimental and analytical results of the compressive behavior of the members, equations for estimating the ultimate compressive strengths of the CFFT and the RCFFT were proposed. In addition, the degree of improvement on the flexural performance of the RCFFT member strengthened by the FRP was analyzed from the flexural tests.

Modification of Campylobacterjejuni Broiler Colonization by a Feed Additive Composed of Encapsulated Organic Acids and Essential Oils

The objective of this study was to evaluate the effect of a novel feed additive on chicken intestinal colonization and carcass contamination by Campylobacterjejuni. The feed additive was composed of microencapsulated organic acids and essential oils （OA/EO）. The feed additive tested was provided by Jefo Nutrition Inc., St-Hyacinthe, Quebec, Canada. Day-old birds were separated into two rooms and subdivided into two groups. Chicken were fed with OA/EO or not fed with OA/EO until they reached 35 d of age. At 14 d of age, chickens received an oral suspension of two well characterized C. jejuni strains, depending on the room they were housed in. The levels of C. jejuni were periodically monitored in the caecum and on the carcasses. C. jejuni colonization was further characterized by the use of high-resolution melt analysis of the C. jejuniflaA gene （HRM-flaA）. The effect of the feed additive was strain-dependent. In room two, the feed additive had no effect on the caecal counts. In room one, at 35 d of age, caecal C. jejuni counts were higher with OA/EO, as opposed to carcasses counts which were lower in the treated group. The HRM-flaA analysis showed that an amplification profile was predominant in birds fed with OA/EO at 35 d of age in room one, suggesting the selection of a C. jejuni strain. In conclusion, the OA/EO seemed to be effective to reduce C. jejuni levels but this effect appeared strain dependent.

Study on Preparation of Ceramic Material and Its Properties

This paper introduces the classification, properties and application of porous ceramic materials, reviewed preparation of porous ceramics. Taking fly ash and red mud as the main raw material to generate porous ceramics, the paper study the influence of different proportions of raw materials, sintering temperature, porosity of porous ceramic sample rate, bending strength, and microstructure. The results show that, fly ash and red mud proportioning and sintering temperature are the main factors that influence the structure and properties of samples. The4#sample is a kind of high porosity and high strength quality of porous ceramics.

Construction of mTNFR1shRNA Plasmid and its Biological Effects on MHV-3 Induced Fulminant Hepatitis in BALB/cJ Mice

Previous study on TNFRl-mediated hepatocyte apoptosis has been implicated in the development of fulminant viral hepatitis. To interfere with the potentially effective target, plasmid named p-mTNFRlshRNA complimentary to the sequence responsible for mTNFR1 was also constructed and further confirmed by sequence analysis. To investigate the effect of mTNFRlshRNA plasmid on mTNFR1 expression in vivo and the disease progress in MHV-3 induced fulminant hepatitis mice model. By hydrodynamic injection of mTNFRlshRNA plasmid, the survival rate of mice, hepatic pathological change were examined and compared between mice with/without mTNFRlshRNA plasmid intervention. The expression of mTNFR1 was detected by Real-time PCR, immunohistochemistry staining. The mTNFRlshRNA plasmid significantly reduced mTNFR1 expression in vivo, markedly ameliorates inflammatory infiltration, prolonged the survival time period and elevated the survival rate from 0 up to 13.3% in Balb/cJ mice with MHV-3 induced fulminant hepatitis. This study was designed to explore the opportunity of RNA interference technique in inhibiting TNFR1 expression, which has been reported to be involved in the development of a variety of diseases including fulminant viral hepatitis and severe chronic hepatitis B.

Flexural and eigen-buckling analysis of steel-concrete partially composite plates using weak form quadrature element method

Flexural and eigen-buckling analyses for rectangular steel-concrete partially composite plates(PCPs)with interlayer slip under simply supported and clamped boundary conditions are conducted using the weak form quadrature element method(QEM).Both of the derivatives and integrals in the variational description of a problem to be solved are directly evaluated by the aid of identical numerical interpolation points in the weak form QEM.The effectiveness of the presented numerical model is validated by comparing numerical results of the weak form QEM with those from FEM or analytic solution.It can be observed that only one quadrature element is fully competent for flexural and eigen-buckling analysis of a rectangular partially composite plate with shear connection stiffness commonly used.The numerical integration order of quadrature element can be adjusted neatly to meet the convergence requirement.The quadrature element model presented here is an effective and promising tool for further analysis of steel-concrete PCPs under more general circumstances.Parametric studies on the shear connection stiffness and length-width ratio of the plate are also presented.It is shown that the flexural deflections and the critical buckling loads of PCPs are significantly affected by the shear connection stiffness when its value is within a certain range.

Microstructure and mechanical properties evolution of 65Cu-35Zn brass tube during cyclic rotating−bending process

The cyclic rotating−bending(CRB)processes under different deformation conditions were carried out to refine the microstructure and improve the mechanical properties of the 65Cu−35Zn brass tubes.The microstructure and the mechanical properties in the axial direction of the tubes after the CRB process were studied with the OM,EBSD and conventional tensile test.To obtain the accumulated effective plastic strain of the tube during the CRB process,the FEM simulation was also executed.The results show that the average grain size decreases with the increase of rotation time at RT,and with the decrease of bending angle at 200℃.With the increase of accumulated effective plastic strain during the CRB process,the reduction rate of average grain size of the brass tube increases,the tensile strength of the brass tube increases in wave shape and the elongation increases first and then sharply decreases.

采用双向斜拉式弯曲划分的曲线渐进化简方法

目的曲线化简是制图综合中的经典研究问题和重要研究内容,以往曲线化简以顶点压缩为主,而制图综合中曲线化简是渐进删除小弯曲,保留特征弯曲的过程,因此提出一种以弯曲为化简单元的曲线化简方法。方法通过弯曲划分、弯曲渐进取舍实现线要素化简:分析斜拉式弯曲划分方法优点与不足的基础上,提出一种双向斜拉式弯曲划分方法,使弯曲划分结果更加准确、完整;在双向斜拉式弯曲划分的基础上,探测弯曲间关系,将具有不同关系的弯曲定义为3类弯曲,并在此基础上划分两类弯曲组;对不同类型的弯曲组采用不同的弯曲取舍方法及取舍顺序,渐进删除弯曲,避免化简过度;重复弯曲划分、弯曲关系探测、弯曲取舍等过程,直至化简结果中不存在目标尺度下不可见的细小弯曲为止,实现曲线渐进化简,充分化简曲线以满足目标尺度下视觉要求。结果以某地区1∶25万的水系数据为实验对象,实验1分别利用双向斜拉式弯曲划分方法和斜拉式弯曲划分方法对其中16条线状河流要素划分弯曲单元,双向斜拉式弯曲划分方法划分的弯曲单元形态上更符合认知规律,且划分结果较斜拉式弯曲划分结果更加完整,避免了弯曲遗漏;实验2分别利用D-P算法、基于三元组的曲线化简方法、本文方法将16条线状河流要素由1∶25万分别化简至1∶50万、1∶100万、1∶200万,本文方法的各尺度化简结果较另两种方法在认知层次、几何层次、地理层次上都具有一定优越性;实验3增加实验数据量,对956条不同形态曲线构成的水系依实验2进行对比化简实验。计算每条曲线利用不同方法化简至各尺度后产生的位置误差,并统计不同结果中所有曲线位置误差的平均数、加权平均数、中位数等统计值量化评估化简结果,本文方法各尺度化简结果中位置误差的统计值均小于另两方法同尺度化简结果中位置误差的统计值。结论双向斜拉式弯曲划分方法划分曲线弯曲更加完整、准确、符合认知,采用双向斜拉式弯曲划分的曲线化简方法符合人工化简过程和认知规律,在形态保持、地理特征保持等方面都有一定优势,适于多种形态曲线化简,用于形态相对曲折、复杂的线要素化简时优势明显,适用于制图综合实际应用。

基于相似变换理论的膜张力-位移相关公式研究

以薄板的大挠度弯曲微分方程组为基础,以平面内可自由滑动、平面外无位移的局部测量范围内膜材为边界条件,推导出不同材性膜材的位移与张力对应比例关系。结合鹿岛建设株式会社的试验,得到双向等张力情况下膜张力-位移相关公式,该公式适用于各向同性与正交异性的膜材。ANSYS有限元验证表明,该公式具有很高的精度,可以满足工程需要。

On Light-Like Extremal Surfaces in Curved Spacetimes

In this paper, we find that under a diffeomorphic of nonlinear geodesic equations are concerned with light-like extremal surfaces in curved spaeetimes. It is interesting to transformation of variables, the light-like extremal surfaces can be described by a system Particularly, we investigate the light-like extremal surfaces in Schwarzschild spacetime in detail and some new special solutions are derived systematically with aim to compare with the known results and to illustrate the method.