天然胶原的稳态流变性能和数学模拟

用旋转流变仪研究胶原溶液的稳态流变性能,讨论了浓度和温度的变化对胶原溶液流动曲线的影响。实验数据显示胶原溶液的剪切粘度随着剪切速率的增大而降低,表明胶原溶液具有明显的假塑性。同一剪切速率下,温度升高,胶原溶液的剪切粘度降低;浓度增大,剪切粘度增大。用幂律方程、Carreau方程和Cross方程对胶原溶液的流动曲线进行数学拟合,结果表明幂律方程,Carreau方程和Cross方程都能准确地描述胶原的流动曲线,其中幂律方程的粘度指数K和非牛顿指数n的变化能准确反映胶原假塑性的变化;Carreau方程和Cross方程的参数比幂律方程多,其拟合得到的曲线和实验数据吻合得更好。但在本实验条件下,Carreau方程和Cross方程预测的零剪切粘度η0和无穷剪切粘度η∞不准确。     

PF—Ⅱ尼龙流变行为研究

用ＸＬＹ－Ⅱ型流变仪研究了ＰＦ－Ⅱ尼龙的流变行为，得到了熔体表现粘度与温度，剪切应力，剪切速率的流动曲线以及剪切应力与剪切速率的关系，结果表明，ＰＦ－Ⅱ尼龙是非牛顿假塑性流体；表观粘度与温度关系符合Ａｒｒｈｅｎｉｕｓ方程，随温度升高，非牛顿指数变大，在２１０～２５０℃范围内，其非牛顿指数ｎ为０．４９～０．６５，恒剪力应力τ，下的粘流活化能∧Ｆ，随τ的增大而稍在减小。     

聚乙烯醇缩丁醛/聚乙二醇体系的流变性能

采用美国TA公司的AR2000型应力控制流变仪研究了聚乙烯醇缩丁醛/聚乙二醇(PVB/PEG)体系的流变学性能,研究了温度、PVB质量分数与PEG分子量对PVB/PEG体系的流动曲线和非牛顿指数等流变特性的影响。结果表明PVB/PEG体系存在剪切变稀行为,为假塑性流体;温度升高,表观黏度减小,非牛顿指数增大;PVB质量分数增加,表观黏度增加,非牛顿指数减小;PEG分子量增加,表观黏度增加,非牛顿指数变化很小。在一定的浓度和剪切速率下体系的黏度随温度的变化符合Arrhenius方程式,粘流活化能随剪切速率的增加而减小。     

胶原溶液流变性能的研究

以纯化猪皮为原料提取胶原,配制不同浓度胶原溶液研究其流变性能,采用幂律方程拟合流动曲线,拟合程度非常高,以黏流活化能分析了黏度对温度的依赖性。讨论了胶原溶液浓度、剪切速率、温度对其黏度的影响。结果表明,该胶原溶液具有假塑性流体特征,浓度越高,非牛顿指数n越小,假塑性越强,黏度随剪切速率增大而下降的程度越明显。相同剪切速率下,温度升高,各浓度胶原溶液黏度下降。浓度越高,黏流活化能越大,对温度越敏感。     

聚乙烯醇水溶液的剪切流变行为

研究了不同浓度和分子量的聚乙烯醇(PVA)水溶液的流变性能。讨论了剪切速率和温度对PVA水溶液的表观黏度、非牛顿指数和粘流活化能的影响。实验结果表明,随剪切速率增加,不同浓度和聚合度样品间黏度的差别降低,所有PVA水溶液均显示剪切变稀行为。随PVA浓度提高,溶液的非牛顿指数是先增大后降低。同时发现剪切速率的变化影响PVA水溶液黏度的温度依赖性。     

不同分子量丙烯腈-丙烯酰胺共聚物溶液的流变性研究

将不同分子量的丙烯腈（AN）与丙烯酰胺（AM）的共聚物溶解于二甲亚砜（DMSO）中，获得聚丙烯腈（PAN）溶液。采用旋转粘度计和锥板流变仪，从非牛顿指数n、流动活化能△Eq、结构粘度指数△ηa和弹性模量G等方面比较了不同分子量PAN溶液的流变性能。结果表明，分子量高的PAN溶液的表观粘度对应力变化敏感，分子理低的PAN溶液的表现粘度对温度的变化敏感，无论是从粘性还是从弹性角度看，低分子量PAN溶液的物理稳定性好。     

丁二烯-苯乙烯嵌段共聚物溶液粘度的测定和研究

采用NEX－1型锥板粘度计和HAAK－100型锥板粘度计测定了丁二烯－苯乙烯嵌段共聚物（SBS）两种型号SBS1401和SBS4402的环己烷溶液和甲苯溶液的粘度,温度范围为20℃-60℃,浓度范围为1％－25％。研究了各种因素对溶液粘度的影响,并计算出了运动粘度。8％以下溶液呈现牛顿流体的性质,粘度基本不随剪切速率改变。浓度从10％起,溶液呈现出非牛顿性,粘度随剪切速率呈幂率变化,粘流活化能随剪切速率的增加而增高。在本文的测量范围内,绝对粘度与浓度呈三次多项式的关系,运动粘度与浓度呈指数关系。     

胶原/异丙醇共混溶液的稳态流变及其触变行为

采用流变仪考察了异丙醇对胶原溶液稳态剪切、屈服应力和触变性质的影响。实验表明,在低剪切速率下,异丙醇的浓度对体系的粘度影响较大,在高剪切速率下各体系粘度则对异丙醇浓度不敏感。幂律方程和Carreau方程能很好地拟合胶原/异丙醇共混溶液的流动曲线,通过粘度系数K、非牛顿指数n和零剪切粘度η0等准确地描述共混溶液的流变性质。通过屈服应力测试发现,异丙醇的加入降低了体系的屈服应力,改善了胶原的流动性质,但同时也使体系不稳定程度增加。另外含有1mol/L异丙醇的共混溶液触变面积小于纯胶原溶液,受剪切破坏的结构能较快速恢复,而含有2和3mol/L异丙醇浓度的共混溶液触变面积大于纯胶原溶液,受剪切而破坏的结构恢复慢,溶液不稳定性增加。     

胶原/甘油共混溶液的流变性能

采用旋转流变仪和动态流变仪研究胶原/甘油共混溶液的稳态和动态流变性能,考查温度、剪切速率和胶原浓度对流动曲线的影响.结果表明,胶原/甘油共混溶液是假塑性流体,非牛顿指数,n随着甘油浓度的增加而减小,甘油的存在降低了共混溶液对温度依赖性,具体表现为:共混溶液n值的变化范围明显减小,流动曲线稳定.提高剪切速率比升高温度更能有效改善胶原/甘油共混溶液的流动性.体系中胶原浓度的改变,对共混溶液的粘弹性影响较大.     

高分子量微生物纤维素LiCl/DMAc纺丝溶液流变性研究

微生物纤维素溶液流变性能对其纺丝工艺研究具有重要的指导意义,以8%LiCl/DMAc为溶剂采用旋转流变仪对不同分子量、不同固含量溶液的稳态流变及动态流变进行了测定。结果表明:微生物纤维素的LiCl/DMAc溶液属于非牛顿假塑性流体;高分子量的溶液比低分子量的溶液黏度要高;随温度的升高,溶液表观黏度不断下降,高浓度的溶液在低剪切速率下对温度更敏感,且浓度越高,结构黏度指数越大,纺丝难度越大。通过动态流变得知,溶液浓度越高,体系弹性强度及黏滞力越大,但对外部剪切力越敏感,其物理稳定性越弱。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from