Design and Structure Optimization of Plenum Chamber with Airfoil Baffle to Improve Its Outlet Velocity Uniformity in Heat Setting Machines

The plenum chamber of a heat setting machine is a key structure for distributing hot air to different air channels.Its outlet velocity uniformity directly determines the heating uniformity of textiles,significantly affecting the heat setting performance.In a traditional heat setting machine,the outlet airflow maldistribution of the plenum chamber still exists.In this study,a novel plenum chamber with an airfoil baffle was established to improve the uniformity of the velocity distribution at the outlet in a heat setting machine.The structural influence of the plenum chamber on the velocity distribution was investigated using a computational fluid dynamics program.It was found that a chamber with a smaller outlet partition thickness had a better outlet velocity uniformity.The structural optimization of the plenum chamber was conducted using the particle swarm optimization algorithm.The outlet partition thickness,the transverse distance and the longitudinal distance of the optimized plenum chamber were 20,686.2 and 274.6 mm,respectively.Experiments were carried out.The experimental and simulated results showed that the optimized plenum chamber with an airfoil baffle could improve the outlet velocity uniformity.The air outlet velocity uniformity index of the optimized plenum chamber with an airfoil baffle was 4.75%higher than that of the plenum chamber without an airfoil baffle and 5.98%higher than that of the conventional chamber with a square baffle in a commercial heat setting machine.

Hydration Heat Evolution of Cement and Its Relation With Setting Time

In order to veritably measure the first peak of hydration heat evolution that has been illustrated important in indicating cement behavior in early hydration, an improved way of water addition into cement in isothermally calorimetric experiment is put forward. The experimental results indicated that: the magnitude of first peak of heat evolution varies from sample to sample, correlation between heat evolution during first peak of heat evolution and initial (as well as final) setting time is unsatisfactory when samples are not classified; while groups of sample classified based on strength grade represent satisfactory correlations, which indicating the existence of close relation between hydration heat evolution in much earlier hydration age and setting property of cement in rather later age. Importance of first peak in hydration heat evolution for understanding cement setting property and reasons for sample classification are also discussed in this paper.

Geodynamic Development of Eurasian Active Margin during Closing of Thetys Ocean, Depending on the Scale of Mantle-Crustal Sources Influence at Pre- and Post-collision Settings, Controlled by Geological and Geochemical Indicators

Phanerozoic geodynamic evolution development of Tethys Ocean,its collision and closing,revealed at the Eurasian active margin in pre-and post-collision stages during convergence of Afro-Arabian and Eurasian continents.Subduction of oceanic slab under continental margin revealed in steady state subduction and steepening of subducting slab provoked the incursion of mantle diapir.The steady state subduction is related with island arc setting whereas steepening provoked incursion of mantle diaper interarc-backarc and minor ocean settings.They are controlled by geological indicators—volcagenic,petrochemical,geochemical,tectonic and metallogenic.Each of them is determined by scale of mantle-crustal influence,controlled by intensity and level of mantle diapir incursion in the crust rising from interarc-backarc to minor oceanic setting.The island arc setting is characterized by blocking,which as others by extension of rifting(interarc-backarc)caused spreading out from zone of volcanic activity and mineralization sialic crusts,whereas minor ocean setting caused by spreading out from zone of volcanic activity and mineralization sialic and basaltic crusts.So mantle crustal influence rising from island arc to minor ocean settings controlled type of volcanism and mineralization in pre-collision development.At the closing of ocean occurred the precollision setting which is transferred in post-collision revealed in orogenesis.It is divided in two stages.The first initial stage occurred in penetration hot fluids from the mantle in sialic crust smelted from in granitoid melt and leached the gold and trace melts Sb,W,Mg and Hg from sialic crust.The latter are geochemical indicators of post-collision setting.The second final stage revealed in shoshonite-basalt volcanism activity occurred with penetrated mantle material into deep volcanic chambers and characterized with increasing of mantle influence than initial stage of post-collision activity.

Influence of Heat Setting on Mechanical and Structural Properties of Polypropylene Hernia Mesh

Heat setting has important effects on mechanical and structural properties of polypropylene( PP) mesh. However,there is no systematic study on the effects of heat setting. In this paper,the orthogonal array was designed for heat setting,and the influences of heat setting on structural, mechanical properties and flexural rigidity of PP mesh were studied. The experimental results showed that temperature had larger influence than tension and time on thickness,tensile strength,bursting strength, tear strength and bending stiffness of PP meshes, except the fabric weight. The optimum heat setting parameters were as follows: temperature was120 ℃, time was 10 min,and tension was small. These results will provide guideline for the selection of heat setting parameters.

Heat Setting Technology for the Glove of Flexible Medical Orthosis

In order to meet the curative effect,the glove of the flexible medical orthosis was designed to use nylon / spandex and polyester / spandex covered yarns to knit the glove by parts.For the purpose of confirming the best heat setting technology of the glove knitted by multicomponent materials, different heat setting technologies with different temperature and time were tested on the nylon / spandex and the polyester / spandex knitted fabrics.And the effects of the heat setting technology on dimensional stability and elastic recovery of the two kinds of fabrics were analyzed as well.The results show that in the proper range of temperature and time,dimensional stability and elastic recovery of the nylon / spandex knitted fabric become better with the increases of temperature and time.And dimensional stability of the polyester / spandex knitted fabric also turns good.But its elastic recovery doesn't change obviously.All the measured values were compared with each other.And the results indicate that dimensional stability and elastic recovery of these two kinds of fabrics both are great after the heat setting technology of temperature 180 ℃ and time 60 s.

Effect of Heat-Setting on Structural Parameters and Mechanical Properties of PP Monofilament Hernia Patch

General surgery hernia is a common and frequently- occurring disease in the world. In the tension-free hernia repair surgery, polypropylene （PP） patch has been confirmed as the most popular surgical implants. In this study, domestic medical PP monofilament was selected as raw material whose diameter was 0.15 mm, and the patch was knitted in the warp knitting machine of 12E gauge with one bar. Using the method of orthogonal experiment with three factors and three levels, the best heat-setting process of PP mesh was determined at the temperature of 130 ~C with 10 min under tension-free conditions. The relationship between heat-setting tension and performance of the patch was discussed. Patches with different porosity were prepared, and then structural parameters including density, thickness, porosity, and mechanical properties including tensile breaking strength, bursting strength, tearing strength, flexural rigidity and suture pulling out strength were tested and compared. The experimental results show that： the smaller of the patch＇s density, the higher of the porosity; other properties including density, thickness, bending stiffness, tensile breaking strength, bursting strength, tear strength, and suture pulling out strength reduce in varying degrees. This different degree of reduction is worth summarizing.

HEAT KERNEL ESTIMATES ON JULIA SETS

We give heat kernel estimates on Julia sets J（f;） for quadratic polynomials f c（z） = z;+ c for c in the main cardioid or the ±1/k-bulbs where k ≥ 2. First we use external ray parametrization to construct a regular, strongly local and conservative Dirichlet form on Julia set. Then we show that this Dirichlet form is a resistance form and the corresponding resistance metric induces the same topology as Euclidean metric. Finally, we give heat kernel estimates under the resistance metric.

Effects of Fillerwire Composition along with Different Pre- and Post-Heat Treatment on Mechanical Properties of AISI 4130 Welded by the GTAW Process

This research intends to find out the optimal mechanical properties of AISI 4130 steel welded by the GTAW process. Six test plates were joined by two types of filler wire with similar chemical composition to the base metal, and with lower carbon content and slightly higher alloy elements content compared to the first one. Test plates then exerted three different pre-heat and post-heat treatments on both groups. The three types of heat treatments were alternatively without pre-heat and post-heat, with pre-heat only, and finally with pre-heat and post-heat. Tensile, side bends and impact tests (for weld zone and HAZ) have been conducted. Results show that using low-carbon filler wire along with pre- and post-heat resulted in outstanding mechanical properties.

Power-Heat-Set:地毯丝热定型——采用过热蒸汽或饱和蒸汽

纺织工业中的热定型是描述大多数情况下在蒸汽或干燥热环境中进行热加工的一个术语。热定型赋予纤维、纱线或织物尺寸稳定性和其他所要求的属性,如高蓬松性、抗折皱性或耐温性。热定型也用来改进后继加工的属性。

超大型侧吹熔池熔炼余热锅炉烟气流动及烟尘黏附研究

富氧侧吹熔池熔炼广泛应用于铜、铅、锌等有色金属的提取,其后端的余热锅炉承载着余热回收利用、沉降烟尘的重要作用。但在实际生产过程中,炉内烟气流场混乱,烟尘易黏附积灰,炉壁与部件磨损严重等,导致了余热回收效率降低,低负荷运行甚至被迫停机。针对上述问题,采用多相网格质点方法,对年处理150万t精矿超大型富氧侧吹熔池熔炼余热锅炉内烟气流动特性、烟尘沉降与黏附开展数值模拟研究。结果表明:炉内的烟气涡旋会导致烟尘回流至入口烟道;挡板前移会导致挡板受击与堵塞情况加剧;增大挡板间距能有效减小挡板的堵塞;增大辐射室空间能大幅度减小挡板受到的冲击。

基于格子Boltzmann方法的地埋管管群换热的模拟研究

土壤结构和地下水通常会影响地埋管换热器的传热,本文将利用随机四参数生成法建立双分布函数格子Boltzmann模型,对有渗流条件下地埋管管群换热器与饱和土壤多孔介质的换热情况进行了模拟,分析了影响埋管外土壤平均温度的主要因素。研究表明,土壤热传导特性主要受土壤孔隙度、地下水渗流速度和土壤骨架导热系数k s的影响。本文的研究结论对考虑土壤渗流的地下换热器的设计具有一定的指导意义。

BLOW UP POINT SET OF POSITIVE SOLUTION FOR NONLINEAR HEAT EQUATION

In this paper we consider a class nonlinear heat cquation,with non-local ferm and study that the structure of blow up point set of positive solution of initial boundary value problem in nonsymmatric convex domain.

基于热传递减法集对势的区域水资源承载力评价

为有效评估区域水资源承载力系统演变特征并诊断脆弱性影响因素,引入物理学热传递思想,在集对分析传统减法集对势基础上进一步深化确定性项和不确定项之间的势差概念,构建了基于热传递减法集对势的区域水资源承载力评价方法,并应用于安徽省江淮丘陵区。结果表明:2011—2018年安徽省江淮丘陵区除合肥市外,其余地市水资源承载力水平整体有所改善,合肥市水资源承载力等级较低;人均水资源量、产水模数、生态用水率等因素是影响安徽省江淮丘陵区水资源承载力变化的重要脆弱性因素。整体而言,本文计算分析结果与传统减法集对势及半偏减法集对势计算结果基本一致,这表明构建的基于热传递减法集对势的水资源承载力评价方法计算结果合理有效,且丰富和发展了集对势的内涵,可为开展区域水资源承载力评价及脆弱性因素识别提供新的研究途径。

Lyocell长丝热定型工艺对其结构性能的影响

针对Lyocell长丝热定型工艺尚不明确的问题,采用干喷湿纺技术制备Lyocell水洗丝,研究热定型张力、温度和时间等工艺参数对Lyocell长丝力学性能和尺寸稳定性的影响,并结合广角X射线衍射、小角X射线散射以及双折射率等测试分析了不同条件下长丝结晶、取向以及微孔等结构的变化规律,阐明了热定型条件下长丝结构与性能的关系。结果表明:温度为110~130℃时,3 min的热定型可保证长丝中水分的去除,在热定型过程中长丝的晶区结构基本不变,微孔尺寸的减小以及非晶区纤维素分子链段的收缩,提高了长丝的致密化程度并降低了取向程度;施加0.5~2.3 cN/dtex的张力,长丝的断裂强度、初始模量不易发生弱化,且干热收缩率低于0.7%。施加适当张力的热定型有效抑制了非晶区链段的解取向,保持了纤维高结晶、高取向的结构特点,从而保证了Lyocell长丝的力学性能和尺寸稳定性。

采用扭曲片内插件的管壳式换热器自动设计新方法

管壳式换热器作为应用最广泛的换热器,对其进行优化设计是一个十分重要的研究主题。现有的设计方法多数是基于启发式方法求解或调用商业求解器,其运算速度较慢且不能保证设计解的质量。本文将集合修剪算法应用于管壳式换热器的自动设计,将管外径、管长、壳程直径、管程数、扭曲片节距、扭曲片厚度等定义为离散变量后输入,程序自动输出设计结果与方案。对采用扭曲片内插件的管壳式换热器进行自动设计优化,分别以最小化换热面积、年度总费用、净现值作为优化目标进行单目标优化。对比发现集合修剪算法可以保证设计解的全局最优,同时降低优化求解时间,可在0.5~2s内给出结果。以换热面积最小化为目标函数的优化结果显示,集合修剪算法可得到更小的换热面积,比文献值减少了0.7%,同时采用强化传热可减少换热面积。热流分配在管程时,强化技术降低了7.7%的换热面积,管程侧的压降则提高了16.9%;热流分配在壳程时,则降低14.6%的换热面积,管程压降提高了98.7%。以最小化年度总费用和净现值为目标的优化结果显示,强化传热的费用低于未强化情况,热流分配在管程时费用降低13.1%,分配在壳程时则降低0.57%。此外,换热器的费用也会受到成本参数的影响。

基于PSO-ELM组合算法的热力站负荷预测研究

提出了一种粒子群优化极限学习机(PSO-ELM)算法用于热力站负荷预测,应用粒子群(PSO)算法优化极限学习机(ELM)的输入权值和隐含层阈值。将提出的组合算法应用于天津市某小区热力站的负荷预测中,并与ELM、支持向量回归(SVR)和粒子群优化支持向量回归(PSO-SVR)算法在同等条件下进行比较。结果表明,PSO-ELM在预测精度上优于其他算法;在热负荷波动较大时,表现优于PSO-SVR;在一定范围内样本容量对预测结果影响不大,PSO-ELM可遗忘更多的数据。

导电纱线及柔性传感器耐久性影响因素研究

为了探究影响导电纱线及柔性传感器耐久性的因素,本文选取5种典型金属导电纱线,首先分析洗涤次数、热定型温度及氧化时间对其电阻的影响。然后,以77 dtex镀银导电纱线织造不同尺寸的柔性传感器,进行30次洗涤测试,并用活性藏青BF-DB进行染色处理,以此分析洗涤和染色对传感器性能的影响。结果表明:三种因素对铜纤维的导电性能影响最大,而对铜丝和不锈钢导电纱线的导电性能影响最小,其耐洗涤性、耐热性及抗氧化性能良好。锦纶基镀银导电纱线电阻随着热定型温度的增大而减小,长度缩短;洗涤次数增加,其电阻有一定程度增大;氧化处理20 d后导电性能明显减弱。镀银导电纱编织的柔性传感器较耐洗涤,染色处理后其尺寸变小,但能维持稳定的导电性。

卷烟加热棒测温仪的设计和不确定度分析

针对烟草行业,目前尚未存在检测加热卷烟烟具加热温度及温度均匀性的检测装置和方法,为了解决在狭隘空间内对微型棒状加热片的测温需求,本文研制了一种卷烟加热棒测温仪,并设计了一种适用于卷烟加热棒测温的新型结构。为了验证卷烟加热棒测温仪测量结果的准确性与可靠性,对测温仪进行不确定度分析。分析结果依据《GB/T 13283-2008工业过程测量和控制用检测仪表和显示仪表精确度等级》标准,在量程为100℃~400℃,满足0.1级要求。最后实验验证可以有效测量不同烟支的加热温度场情况。

1961―2022年新疆棉花花铃期高温热害时空变化规律研究

【目的】高温热害是新疆棉花花铃期最主要的气象灾害,严重制约着棉花的安全生产。明确该地区高温热害的演变特征,为科学制定防灾减灾措施提供参考依据。【方法】基于新疆植棉区55个国家基本气象站1961―2022年日最高气温资料以及24个棉花气象观测站1991―2022年棉花开花期、吐絮期观测资料,结合棉花花铃期高温热害监测指标,利用气候倾向率、Mann-Kendall突变检验等分析方法,揭示新疆棉花花铃期不同等级高温热害的时间和空间变化规律。【结果】1961―2022年新疆植棉区花铃期日最高气温、极端高温(日最高气温≥38.0℃)和极端高温累计日数呈极显著上升趋势,气候倾向率分别为0.16℃·(10 a)^(-1)、0.07℃·(10 a)^(-1)和0.45 d·(10 a)^(-1)。新疆各植棉区棉花花铃期高温热害发生的频率和强度均呈增加趋势。1961―2022年东疆亚区96.0%以上的年份发生了不同等级的花铃期高温热害,南疆亚区花铃期轻度和中度热害发生频率分别为88.7%和51.6%,北疆亚区花铃期轻度热害发生频率为64.5%。【结论】新疆植棉区花铃期高温热害发生的频率和强度呈现出“东强西弱,南多北少”的区域性特征。新疆植棉区应注重耐高温棉花品种的选育与应用推广,合理调整棉花种植布局,加强气象灾害监测与预警工作,保障新疆棉花生产安全稳定发展。

脱硫石膏对碱激发胶凝材料性能及微观结构的影响

将工业副产脱硫石膏引入碱激发胶凝材料,拟解决其高碱含量时凝结硬化过快问题,同时考察力学性能和水化反应特征,研究脱硫石膏对碱激发胶凝材料宏观性能影响规律,采用X射线衍射(XRD)、扫描电子显微镜(SEM)等微观分析手段探索脱硫石膏对碱激发胶凝材料的作用机理。结果表明:脱硫石膏的引入可以有效延缓碱激发胶凝材料的凝结时间,且脱硫石膏掺量与凝结时间呈正相关,与强度、水化速率和累积放热量呈负相关,综合考虑,脱硫石膏掺量不宜超过9%(质量分数);脱硫石膏掺入后,碱激发胶凝材料水化产物中并未生成大量钙矾石晶体,且微观结构疏松,从而导致材料强度降低。