脂肪酸稀土用作PVC热稳定剂的压析和喷霜特性

研究了常见脂肪酸的稀土盐用作ＰＶＣ 热稳定剂的压析和喷霜特性。结果表明，与常用金属皂（ 如钙、锌皂） 有所不同，硬脂酸稀土不但喷霜小，压析也小；脂肪酸稀土的压析和喷霜具有相似的递变规律：硬脂酸稀土～棕榈酸稀土～肉豆蔻酸稀土～月桂酸稀土＜ 葵酸稀土＜ 辛酸稀土。

聚乙烯蜡和硬脂酸钙在聚氯乙烯中的压析特性与机理

采用转矩流变仪颜色转移法,测试了聚乙烯蜡A-C 617A及硬脂酸钙(Ca St2)在硬质聚氯乙烯(PVC)中的压析性。结果表明,A-C 617A和Ca St2均产生压析,当用量为1份时,Ca St2的压析性为9. 3级,而A-C 617A的压析性为0. 3级,Ca St2的压析性明显大于A-C 617A;两者的压析性呈现显著的对抗效应,0. 6份Ca St2的压析性为5. 5级,并用0. 4份A-C 617A后,减小为0. 3级,并用A-C 617A能够显著减小Ca St2的压析性。可以推测,压析形成机理为:由于A-C 617A和Ca St2的极性小于金属表面,均能铺展润湿金属表面,形成粘附层,进而产生压析,且由于Ca St2的极性更强,其压析性更大;当Ca St2与A-C 617A并用时,由于A-C 617A可以插入Ca St2粘附层的非极性尾-非极性尾界面,分散Ca St2为反胶束并溶解Ca St2,减弱了Ca St2粘附层的凝聚力,从而有效减小了其厚度,因此,压析性明显减小。

PVC中润滑剂压析性的转矩流变仪测试方法

对聚氯乙烯(PVC)中润滑剂压析性进行测试评价,以硫醇有机锡为热稳定剂、高相对分子质量的聚酯润滑剂,为脱模剂配制含受试润滑剂和红色颜料的测试配混料及含白色颜料的清理配混料,然后,采用混炼式转矩流变仪先混炼测试配混料,再混炼清理配混料,得到的压析清理料块的着红色度可表征受试润滑剂的压析性。采用混炼式转矩流变仪作为测试仪器,测试条件可精确控制且受环境和操作因素影响较小,测试耗料少、耗时短,而新的配方体系又对软、硬质PVC中各种润滑剂压析性的测试均适用,因此,有效克服了已有技术的缺点,兼具适用面广、重复性高且省料、省时的综合优势。

压延加工中压析现象初探

在ＰＶＣ压延加工中有时发生严重的压折，影响了加工顺利和产品表面质量。本文结合生产实际及教训，对其进行了初步探讨，提出了相应有的效措施。

功能性填料在压析现象中的作用

压析是当PVC配方中某一添加剂的含量超过其可溶度而迁移到表面的现象，通常都携带着颜料或填料颗粒而在加工物体表面沉积后堵塞磨具口。

糖尿病患者血液透析中低血压的影响因素分析

目的探讨糖尿病患者透析中低血压(intradialytic hypotension,IDH)的影响因素。方法选择2017年1月~2019年12月北京3家血液透析中心的糖尿病患者140例,根据IDH的发生频率是否超过30%分为IDH组和非IDH组,记录患者的临床资料,分析2组患者IDH的影响因素。结果IDH组101人,非IDH组39人。Logistic回归分析显示超滤率、透析前收缩压是IDH的独立影响因素,OR值和95%CI:分别为:1.229(1.017~1.487),P=0.033;1.048(1.013~1.083),P=0.007。ROC曲线预测IDH,透析前收缩压的阈值为159mmHg(1mmHg=0.133kPa)(AUC=0.702,95%CI:0.604~0.801,P<0.001);超滤率的阈值为9.5ml/(h·kg)(AUC=0.657,95%CI:0.551~0.762,P=0.004)。结论超滤率、透析前收缩压是糖尿病患者发生IDH的危险因素,建议透析前收缩压质量控制的上限阈值为159mmHg,超滤率的质量控制上限阈值为9.5ml/(h·kg)。

血液透析过程中低血压原因分析及护理

低血压是血液透析患者常见的并发症，出现低血压前，多数患者均有先兆症状，如打哈欠、流泪或自觉寒冷感、疲乏等，如不及时采取有效措施，即可出现低血压的典型症状，如恶心、呕吐、胸闷、乏力、面色苍白、出冷汗、头晕甚至短暂的意识丧失。这不仅影响血透治疗的顺利进行...

负压透析制备人白细胞转移因子

负压透析制备人白细胞转移因子周新华，孙安堂，王吉英，赵凤华（山东省生物制品研究所）转移因子（ＴＦ）是细胞浸出液中可透析物质中的一种具有免疫活性的小分子物质，具有增强机体细胞免疫力的功能。提取转移因子大多采用经典的透析法，需时间长且透析效果往往不十分理...

维持性血液透析患者透析前收缩压变异度与住院情况

目的:统计广州市第一人民医院肾内科血液净化中心128例患者透析前血压控制情况,分析血压变异度对患者住院情况的影响。方法:选择2012年1月于广州市第一人民医院肾内科行维持性血液透析(MHD)的患者128例进行回顾性分析。统计参数包括年龄、性别、原发病因、连续2个月(2011年1-2月)透析前收缩压、残余尿量、2011年1月-2012年1月患者住院次数、总住院日、住院原因等。结果:128例患者平均透前收缩压为(148.53±17.81)mmHg,平均透前收缩压变异系数为(0.090±0.04),25%患者变异系数控制在0.061以内,50%患者控制在0.082以内,75%患者控制在1.140以内;每人年平均住院(1.96±1.06)次,其中,42.7%患者住院1次,28%患者住院超过2次,4%患者住院超过4次;总住院时间为(27.71±22.97)d,其中,25%患者住院天数不超过11d,50%患者住院超过20d,25%患者超过35d。相关分析显示透析前收缩压变异系数与年住院频次(r=0.269,P=0.022)、年住院总天数(r=0.240,P=0.045)成正相关,与年龄、残余尿量、透析龄等无明显相关性。结论:本研究提示MHD患者透析前收缩压波动性越大,患者年住院频次越高,住院持续时间越长。因此,平稳控制患者透析前收缩压,对于改善MHD患者预后至关重要。

300 MW直接空冷汽轮机高背压供热改造浅析

火力发电是煤炭资源最高效的利用形式之一。然而,受环境条件和热力学基本规律的约束,燃煤火力发电的能源转换和利用效率仅能达到40%左右。直接空冷汽轮机的乏汽余热回收可有效降低电厂散热损失,提高电厂整体热效率。回收汽轮机乏汽余热后将极大提高电厂的供热能力。文章介绍300MW直接空冷汽轮机高背压供热的改造方案。

采场底板矿压控制理论的应用

结合实际,谈谈采场底板矿压控制理论的应用。

脂肪酸季戊四醇酯的合成及应用

合成了硬脂酸和2-乙基己酸的季戊四醇酯,研究了2种酯分别与钙锌热稳定剂并用时对PVC(聚氯乙烯)的热稳定效果和压析效果,重点考察了脂肪酸季戊四醇酯的酯化度和脂肪酸碳链长度对PVC稳定性能的影响。结果认为用2-乙基己酸制备的季戊四醇酯稳定效果相对较好。

Extrusion force analysis of aluminum pipe fabricated by CASTEX using expansion combination die

To determine the extrusion force of pipe fabricated by continuous casting and extrusion (CASTEX) using an expansion combination die, the metallic expansion combination die was divided into diversion zone, expansion zone, flow dividing zone, welding chamber, and sizing zone, and the corresponding stress formulae in various zones were established using the slab method. The deformation zones of CASTEX groove were divided into liquid and semisolid zone, solid primary gripping zone, and solid gripping zone, and the formulae of pipe extrusion forces were established. Experiments were carried out on the self-designed CASTEX machine to obtain the aluminum pipe and measure its extrusion force using the expansion combination die. The experimental results of radial extrusion force for aluminum pipe are in good agreement with the calculated ones.

Dual Material Gate SOI MOSFET with a Single Halo

In order to suppress drain-induced barrier lowering in dual material gate SOI MOSFETs,halo doping is used in the channel near the source. Two-dimensional analytical models of surface potential and threshold voltage for the novel SOI MOSFET are developed based on the explicit solution of the two-dimensional Poisson＇s equation. Its characteristic improvement is investigated. It is concluded that the novel structure exhibits better suppression of drain-induced barrier lowering and higher carrier transport efficiency than conventional dual material gate SOI MOSFETs. Its drain-induced barrier lowering decreases with increasing halo doping concentration but does not change monotonically with halo length. The analytical models agree well with the two-dimensional device simulator MEDICI.

Influences of electric-hydraulic chattering on backward extrusion process of 6061 aluminum alloy

The possibility of the electric-hydraulic chattering technology and its application in the cold extrusion were presented.The conventional and electric-hydraulic chattering assisted backward extrusion processes were performed on 6061 aluminum alloy billets at room temperature.The experimental results showed that 5.65% reduction in the extrusion load was attained if the die and ejector were vibrated at a frequency of 100 Hz and amplitude of 0.013 mm in the longitudinal direction.The friction coefficient at the billet and tool system interface determined from the finite element analysis（FEA） decreased from 0.2 without chattering to 0.1 with application of electric-hydraulic chattering.The higher values of instantaneous velocity and direction change of material flow were achieved during the chattering assisted backward extrusion process.The strain distribution of the chattering assisted backward extrusion billet revealed lower maximum strain and smoother strain distribution in comparison with that produced by the conventional extrusion method.

NUMERICAL PREDICTION OF AIRCRAFT HYDRAULIC SYSTEM BASED ON THERMAL DYNAMIC ANALYSIS

A mathematical model of principal elements of the aircraft hydraulic system is presented based on the heat transfer theory. The dynamic heat transfer process of the hydraulic oil and the pump shells within an aircraft hydraulic system are analyzed by the difference method. A kind of means for the prediction to variational trends of the aircraft hydraulic system temperature is provided during operation. The numerical prediction and simulation under the operational conditions are presented for ground trial running and the decelerated operation in flight. Computational results show that there is a good coincidence between the experimental data and the numerical predictions.

Development of Turbocharger for Improving Diesel Engine Matching Performance

The two development ways of turbocharger technology to solve the problem of matching performance with diesel were presented. The ways of waste valve gate turbocharger and variable geometry turbocharger can solve the problem of engine’s low speed torque and achieve lower smoke level. Especially for variable geometry turbocharger, it covers all conditions of engine. It can not only improve the low engine’s speed torque and keep the power performance at high engine speed, but also cover wide engine speed performance that keeps lower fuel consumption and exhaust gas temperature in full load and part load matching. The results of theory analysis and experiment research showed that it’s the ideal solution to solve the matching problem of diesel engines.

Active Vibration Control and Stability Analysis of Cantilever Plate

Active vibration control and stability analysis of cantilever plate are discussed. Based on the analysis of characteristic equation of the closed loop control system, it is shown that such an active control may increase damping properties of the system, meanwhile it may result in instability of the system. It is stable when the feedback only occurs between the collocated sensors and actuators, but it may be unstable when there exists the feedback between sensors and actuators, which mainly depends on the property of the gain matrix of feedback. If the gain matrix is symmetric and definitely positive, the system is stable.

Aging behavior and mechanical properties of 6013 aluminum alloy processed by severe plastic deformation

Structural features, aging behavior, precipitation kinetics and mechanical properties of a 6013 Al–Mg–Si aluminum alloy subjected to equal channel angular pressing （ECAP） at different temperatures were comparatively investigated with that in conventional static aging by quantitative X-ray diffraction （XRD） measurements, differential scanning calorimetry （DSC） and tensile tests. Average grain sizes measured by XRD are in the range of 66-112 nm while the average dislocation density is in the range of 1.20×10^14-1.70×10^14 m^-2 in the deformed alloy. The DSC analysis reveals that the precipitation kinetics in the deformed alloy is much faster as compared with the peak-aged sample due to the smaller grains and higher dislocation density developed after ECAP. Both the yield strength （YS） and ultimate tensile strength （UTS） are dramatically increased in all the ECAP samples as compared with the undeformed counterparts. The maximum strength appears in the samples ECAP treated at room temperature and the maximum YS is about 1.6 times that of the statically peak-aged sample. The very high strength in the ECAP alloy is suggested to be related to the grain size strengthening and dislocation strengthening, as well as the precipitation strengthening contributing from the dynamic precipitation during ECAP.

Experimental research on ultimate bearing capacity of N-joints of grouted square steel tube trusses

Cave-in failure is apt to occur in joints of trusses made of square hollow sections. In order to turn the failure mode into a strength failure mode of joint members, the idea is proposed that the chord of the truss is grouted to increase the cave-in beating capacity of a hollow tube chord. An experiment of eight specimens of N- joints made of grout-filled square steel tubes is performed. Based on the experimental study, the geometrical parameters of specimens are analyzed, and the effects of the confinement index ε, the spacing between the two web members g and the ratio of side length of the vertical web member to that of the chord β on the behavior of specimens are investigated through simulation analysis by simulation analyses, the mechanical properties and the failure an ANSYS program. Based on the test results and modes of this kind of joints are analyzed and the formulae to predict the ultimate bearing capacities corresponding to different failure modes are developed. The ultimate bearing capacity of compressive N-joints is calculated in accordance with the cave-in failure mode of a chord member; the ultimate bearing capacity of tension N-joints is calculated in accordance with the punchingshear failure mode; the ultimate bearing capacity of a chord member is calculated in accordance with the shear failure mode in normal sections.