Stream Surface Strip Element Method and Simulation of Three-Dimensional Deformation of Continuous Hot Rolled Strip

A new method,the stream surface strip element method,for simulating the three-dimensional deformation of plate and strip rolling process was proposed.The rolling deformation zone was divided into a number of stream surface(curved surface)strip elements along metal flow traces,and the stream surface strip elements were mapped into the corresponding plane strip elements for analysis and computation.The longitudinal distributions of the lateral displacement and the altitudinal displacement of metal were respectively constructed to be a quartic curve and a quadratic curve,of which the lateral distributions were expressed as the third-power spline function,and the altitudinal distributions were fitted in the quadratic curve.From the flow theory of plastic mechanics,the mathematical models of the three-dimensional deformations and stresses of the deformation zone were constructed.Compared with the streamline strip element method proposed by the first author of this paper,the stream surface strip element method takes into account the uneven distributions of stresses and deformations along altitudinal direction,and realizes the precise three-dimensional analysis and computation.The simulation example of continuous hot rolled strip indicates that the method and the model accord with facts and provide a new reliable engineering-computation method for the three-dimensional mechanics simulation of plate and strip rolling process.

Influences of Al and Si Powders on Microstructure and Hot Mechanical Properties of Al_2O_3-C Slide Plates

The basic formulation of Al2O3- C slide plates was65%（ in mass,the same hereinafter） white fused corundum particles,25% white fused corundum fines,6% active α-Al2O3 micropowder,4% carbon black and flake graphite, and additional 4% phenolic resin.Based on this formulation,3% Al powder,3% Si powder,and 3% Al ＋ 3% Si powder were used to substitute equivalent white corundum fines to improve the hot mechanical properties of Al2O3- C slide plates. The specimens with dimensions of 140 mm × 25 mm × 25 mm were pressed at 150 MPa,dried at 200 ℃ for 24 h,and hot treated at 1 400 ℃ for 3 h in carbon embedded condition. Then hot modulus of rupture and thermal shock resistance of the specimens were tested and the phase compositions and microstructure were analyzed. The results show that specimen with 3% Al powder has the higher hot modulus of rupture but lower residual modulus of rupture after thermal shock than the specimen with3% Si powder; the specimen with 3% Al ＋ 3% Si powders exhibits the highest hot modulus of rupture and the best thermal shock resistance; the change of mechanical property is closely related with the in-situ formed nonoxides： AlN in the form of bars is formed in specimens with Al powder; fibrous SiC whiskers are formed in specimens with Si powder; in the specimens with both Al and Sipowders,besides AlN and SiC whiskers,hexagonal tabular SiAlON is in-situ synthesized,which interlocks with each other.

黄芩苷微乳凝胶对小鼠镇痛作用的研究

评价黄芩苷微乳凝胶的镇痛作用,为黄芩苷微乳凝胶用于治疗炎症性疾病提供实验依据。采用醋酸扭体试验和热板试验,观察用黄芩苷微乳凝胶对腹腔注射0.7%醋酸及高温致小鼠疼痛反应的作用。小鼠随机分为模型组、扶他林乳胶剂阳性对照组、黄芩苷微乳凝胶低剂量组(含黄芩苷0.25%)、黄芩苷微乳凝胶高剂量组(含黄芩苷1.0%),每天腹部皮肤给药1次,连续给药4 d或7 d。造模后,观察小鼠扭体次数、痛阈相对百分率,计算肝、肾、胸腺、脾指数,对小鼠腹部皮肤肉眼观察并进行HE染色病理组织学检查。结果显示:与模型组相比,黄芩苷微乳凝胶低、高剂量组能够显著降低小鼠扭体次数(P<0.01,P<0.05),黄芩苷微乳凝胶高剂量组能够显著增加痛阈相对百分率(P<0.05),对小鼠体重、脏器指数无明显影响,小鼠腹部皮肤光滑健康无皮疹,组织病理学检查皮下有少量肥大细胞。结果表明黄芩苷微乳凝胶具有一定的镇痛作用和良好的安全性。

基于核偏最小二乘法的热轧板凸度预测

以某2160 mm热连轧生产线为研究对象,结合生产数据和数据驱动算法,提出并建立基于核偏最小二乘法和偏最小二乘法的热轧板凸度预测模型,并对模型的参数进行调整和优化。结果表明:偏最小二乘法模型的预测值与实测值误差为-25~30μm,88.74%的板凸度预测值绝对误差小于10μm;核偏最小二乘法模型的预测值与实测值误差为-25~25μm,91.57%的板凸度预测值绝对误差小于10μm。因此,优化后的核偏最小二乘法模型具有更好的预测效果。

MEMS微热板结构设计与仿真

微热板作为很多微机电系统(MEMS)传感器和执行器的基础结构,对器件性能影响极大,在气体传感器、燃料电池等领域都有着重要的应用。本文提出了几种悬浮式结构的微热板设计,并利用有限元分析方法(FEA),在气体传感器常用的工作温度400℃下,从热稳定性、机械稳定性、功耗和效率多方面对微热板进行了仿真,结果表明:螺旋形微热板的综合性能更好。进一步对可能影响微热板性能的多个因素,如电极电压、支撑层厚度、微加热器线宽间距比等进行了优化,获得了综合性能最优的微热板图形及参数设计。

不同消解方式对原子吸收分光光度法测定土壤中六种重金属的影响

土壤是人类宝贵的资源,与人类生产生活息息相关。但近年来,不少地区的土壤受到了污染和破坏。土壤中的污染主要是铜(Cu)、铅(Pb)、锌(Zn)、镍(Ni)、镉(Cd)、铬(Cr)。当土壤重金属超标后,会在相关的农产品和林产品富集,从而影响产品的安全。因此,快速、安全、准确地检测土壤中重金属元素就显得十分必要。本实验采用电热板消解法、微波消解法和王水消解法处理土壤质控样,使用原子吸收分光光度法对Cu、Pb、Zn、Ni、Cd、Cr进行测定。结果显示:三种消解方式标准曲线的相关系数R2均大于0.995,方法检出限均低于标准要求,符合实验要求。微波消解和电热板消解的精密度好于王水消解。微波消解和电热板消解的准确度较高,回收率均大于90%。

Study on Thermal Insulation Performance of Cross-Laminated Bamboo Wall

In recent years,bamboo,as a green building material,has attracted more and more attention worldwide.Inspired by the investigation of cross-laminated timber in structural systems,a new engineered cross-laminated bamboo(CLB)consisting of the cross lamination of bamboo scrimber plates is proposed in this paper.To evaluate its potential in structural applications,the thermal insulation performances of the CLB walls and CLB walls with the EPS foam plate were studied and evaluated by the temperature-controlled box-heat flow meter method.Test results indicated that the thermal insulation performance improved with the increase of thickness,but different wall configurations had little effect on the thermal insulation performance under the same thickness of the CLB wall.The thermal insulation performance of EPS-CLB composite wall was much better than that of CLB wall.In addition,a relatively acceptable accuracy of the theoretical calculations was proved.Finally,the influence of different locations of the EPS foam plate on heat transfer coefficient can be neglected as it was studied based on the validated numerical models.

固溶处理对Ti-4.5Al-2.5V-1.5Fe-0.25O热轧板材组织及力学性能的影响

研究了不同固溶温度与冷却方式对Ti-4.5Al-2.5V-1.5Fe-0.25O热轧板材显微组织及力学性能的影响。结果表明:热轧合金板材组织主要由α相和β相组成,随着固溶温度从910℃升高到1000℃,板材中α相含量减少而β相含量逐渐增多,初生等轴α相向针状β相转变进而向全片层状β相转变;空冷冷却速度较慢,高温组织有很大一部分发生分解,而水冷冷却抑制高温析出相析出及分解,形成片层状β转变组织;随着固溶温度的升高,合金板材抗拉强度先增加后减小,伸长率降低;940℃固溶后水冷处理的合金板材力学性能最优:抗拉强度1264 MPa,伸长率11.4%。

Thermomechanical Characterization of a Bio-Sourced Material Based on Clay and Alfa Fibers

Bio-based materials are of great interest owing to their abundance and the immense potential they display as an ideal alternative to widely used industrial construction materials(that directly and indirectly harm the environment).In this scope,an in-depth experimental study is presented here on clay-based materials aimed to enhance their properties through the addition of other bio-based components such as fibers,in the present case alfa fiber.The thermal conductivity and mechanical properties(compressive and flexural tensile strengths)of the composite clay-alfa material are analyzed with the percentage of alfa fiber in the matrix ranging from 0%to 4%.It is concluded that a percentage of alfa fibers between 1%and 2%is the most effective to get the required optimization of thermal and mechanical behavior of this bio-based material.

Activation of the corticotropin-releasing factor receptor from the basolateral or central amygdala modulates nociception in guinea pigs

Corticotropin-releasing factor (CRF) is a peptide that is released from the hypothalamus into widespread areas of the brain. Evidence has suggested that CRF is involved as a neuromodulator outside of the hypothalamic-pituitary-adrenal axis, playing an important role in fear, anxiety, depression and pain modulation. Our previous report demonstrated that CRF receptor activation in basolateral (BLA) or central nuclei of the amygdala (CeA) produces innate fear in guinea pigs. Inhibition of these receptors via administration of α-helical CRF9-41 (a nonspecific antagonist) into the CeA or BLA decreased innate fear behavior [1]. Additionally, there is strong evidence that emotional behavior and nociception can be modulated simultaneously. The present study was conducted to investigate the involvement of the CRF receptors of the BLA or CeA in nociception in guinea pigs. Guinea pigs were treated with CRF and α-helical CRF>9-41> in three different doses or injected with α-helical CRF9-41 preceded by CRF into the BLA or CeA, and they were evaluated using the hot plate test. Our findings indicated that activation of CRF receptors in the BLA and in the CeA promoted antinociception, and this effect was reversed by preadministration of α-helical CRF9-41 in the same area. The treatment with α-helical CRF>9-41> per se into the BLA and CeA did not alter nociception. Thus, nociception modulation occurs in a phasic manner, whereas defensive behavior can occur tonically because the α-helical CRF9-41 did not cause any modification on the index of analgesia in the hot plate test but did reduce innate fear behavior [1].

稳态法测量冰的导热系数

基于保护热板法原型,使用干冰-乙醇和乙二醇混合浴制造不同温度稳定低温环境之间的传热代替传统的加热传热,设计了冰的导热系数测量装置,在较大的温度范围(-70~-30℃)内实现了冰的导热系数稳定可靠的测量.同时充分借助电子式温度计高效测量数据,测得了冰在不同温度下和含有不同杂质情况下的导热系数变化规律,实验结果与参考值符合较好.利用杂质对冰的导热系数的影响规律,可以按需求调节冰的导热系数.

改良的热板法制备氧化钼纳米片

三氧化钼(MoO_(3))具有层状结构,在电子和光电子器件领域有着良好的应用前景.本文报道了一种改良的热板法来生长大尺寸的MoO_(3)晶体.这种方法能够在常压气氛下实现快速生长MoO_(3),具有低成本和操作简单等优点.通过改变源温度和衬底种类,可以很好地控制MoO_(3)晶体的生长速率和形貌.同时,通过光学显微镜、原子力显微镜、X射线衍射、拉曼光谱和扫描近场光学显微镜等手段,探究了其结构和物理性质.结果表明,MoO_(3)晶体在具有大尺寸的同时还表现出良好的结晶度.此外,还观察到所制备的MoO_(3)晶面上的双曲声子极化子现象,这一现象有望推动其在纳米电子和纳米光子器件中的应用.

样品尺寸对有效导热系数测量值影响的相关性研究

在工程实践中,样品的尺寸对保温材料有效导热系数的检测有极大影响。以XPS保温板和蒸压加气混凝土砌块为例,采用防护热板法研究了样品的规格尺寸对保温材料有效导热系数实测值的影响,探究了非标准尺寸保温材料的有效导热系数检测方法,结果表明:尺寸规格、拼接材料的导热系数、空气填充量均影响试验检测结果,选择不同导热系数的拼接材料拼接试验样品时,拼接材料导热系数远小于试验样品的导热系数,测得实验结果误差最小;拼接材料导热系数与试验样品的导热系数相近时,选择环形拼接测得实验结果误差最小。在可允许条件下,应用同种材料选择环形拼接,但不宜用不同材料拼接,以免误导工程试验。

热轧板千分尺校准方法分析及不确定度评定

在热轧钢板在轧制过程中为保证钢板尺寸而进行钢板厚度测量,故需要耐高温的特殊千分尺对其进行测量。目前对热轧板千分尺的校准工作依据其他的计量技术规范进行,缺乏针对热轧板千分尺的技术规范。在对热轧板千分尺实际校准的基础上,提出了热轧板千分尺的校准方法。结果表明:采用该校准方法对热轧板千分尺进行校准,能够满足其作为计量器具的使用要求;分析了温度变化为对热轧板千分尺准确度影响,并进行了不确定度评定。

双氯芬酸钠对小鼠炎性疼痛的作用研究

目的:分析双氯芬酸钠对小鼠炎性疼痛的镇痛作用。方法:使用“扭体法”和“热板法”观察不同浓度双氯芬酸钠溶液对注射醋酸和高温引起的小鼠疼痛反应的影响,观察指标包括扭体反应、扭体次数以及镇痛百分率。结果:高浓度(0.45%)的双氯芬酸钠具有较好的镇痛作用,其效果与低浓度吗啡处于同等水平;在所用浓度范围内,随着双氯芬酸钠浓度的升高,其镇痛效果越好,低浓度(0.05%)的双氯芬酸钠镇痛效果不明显。结论:有效浓度的双氯芬酸钠对炎性疼痛具有较好的镇痛作用。

广痛消泡沫气雾剂止痛促愈合的实验研究

目的观察广痛消泡沫气雾剂对小鼠的镇痛作用及对大鼠创面的促愈合作用。方法扭体实验将小鼠随机分为模型组、正常组、强痛定组和广痛消大、中、小剂量组,先予腹腔注射药物,0.5 h后再次腹腔注射0.6%冰醋酸10 mL/kg,观察末次给药后0.5 h内小鼠扭体次数、扭体潜伏时和扭体反应抑制率。热板实验将雌性小鼠随机分为盐水组、强痛定组和广痛消大、中、小剂量组,给药前1 h及给药后0.5 h后测定痛阈值。愈合实验将大鼠分为广痛消组、盐水组和康复新组,用打孔器在大鼠背部制造创面,每日换药1次,至创面完全愈合,观察第3、7、14日创面愈合率及总愈合时间。结果广痛消大、中、小剂量组扭体次数均明显少于模型组和强痛定组(P<0.05),扭体潜伏时均长于模型组和强痛定组(P<0.05);广痛消大、中剂量组痛阈提高百分率均大于盐水组(P<0.05),与强痛定组比较差异无统计学意义(P>0.05)。广痛消组创面愈合率第14日高于盐水组(P<0.05),与康复新组比较差异无统计学意义(P>0.05);愈合时间较盐水组短(P<0.05),与康复新组比较差异无统计学意义(P>0.05)。结论广痛消泡沫气雾剂对小鼠有较好的镇痛作用,对大鼠创面有较强的促愈合作用,剂量越大,疗效越好。

导热系数测定仪的系统稳定状态判定方法研究

由于现有平板导热仪存在测量时间固定且耗时长等不足,为了对现有平板导热仪的测量算法进行改善,通过对热板功率的稳定状态进行判定并加入测量阈值,提出了一种基于稳态法的导热仪系统稳定状态判定方法。实验结果表明:该方法能根据不同的测试试样和不同的测试条件在较短的时间内自动确定系统状态的平衡时刻点,且测量精度符合国家标准、重复性好(小于1%)、线性度高(大于0.998)。

稳态平板法测定绝热材料导热系数实验台优化

传统稳态平板法测定绝热材料导热系数实验台稳定时间长、精度低,难以满足教学要求。针对原实验台存在的问题,对其热保护电气控制系统、水冷系统、热功率测量系统、温度测量系统、机械系统和测控电路系统进行了优化设计。实验结果表明,优化设计后的实验台导热系数测量精度提高了5. 5%,稳定时间缩短了50%以上。该实验台起到了提高实验教学质量,改善实验教学条件的作用,为传统实验台的优化设计提供了新思路。

木荷树皮乙醇提取物抗炎镇痛作用研究

分别采用醋酸扭体法、二甲苯致小鼠耳廓肿胀法、热板致痛法观察木荷Shima superba树皮乙醇提取物对小鼠的镇痛及抗炎作用。结果表明:1)木荷树皮乙醇提取物能够有效地抑制醋酸引起的小鼠镇痛扭体反应。其200mg·kg-1处理组、400mg·kg-1处理组、800mg·kg-1处理组对小鼠的镇痛率分别为37.9%、52.2%和66.7%,阿司匹林200mg·kg-1处理组的镇痛率为37.4%。2)木荷树皮乙醇提取物能够降低二甲苯引起的小鼠耳廓肿胀。其200 mg·kg-1处理组、400mg·kg-1处理组、800 mg·kg-1处理组对小鼠耳廓肿胀的抑制率分别为35.1%、56.8%和69.3%,阿司匹林200mg·kg-1处理组的抑制率为54.9%。3)木荷树皮乙醇提取物能够提高热板致痛的小鼠痛阈值。其200mg·kg-1处理组、400mg·kg-1处理组、800mg·kg-1处理组药后60min,小鼠痛阈提高率分别为50.1%、63.3%和78.3%,阿司匹林200mg·kg-1处理组的痛阈提高率为63.6%。可见木荷树皮乙醇提取物有明显的抗炎消肿、镇痛的作用。

扁桃酸的镇痛抗炎作用研究

目的:观察扁桃酸的镇痛、抗炎作用。方法:50只昆明种SPF级小鼠随机分为5组:空白对照组(生理盐水,0.1 ml/10 g)、扁桃酸高(300 mg·kg^(-1))、中(200 mg·kg^(-1))、低(140 mg·kg^(-1))剂量组、阿司匹林阳性对照组,ig,qd。采用小鼠扭体法和热板法观察扁桃酸的镇痛作用。采用二甲苯涂耳致小鼠急性耳肿胀观察其抗炎作用。结果:扁桃酸各剂量组均能使小鼠扭体次数明显减少,痛阈延长,与空白对照组比较差异有统计学意义(P<0.01)。扁桃酸高剂量组的小鼠扭体次数少于阳性对照组,差异无统计学意义(P>0.05),扁桃酸中、低剂量组的小鼠扭体次数多于阳性对照组,其中低剂量组差异有统计学意义(P<0.05);扁桃酸各剂量组用药前后小鼠的痛阈提高率均比阳性对照组高,其中高剂量组用药前后痛阈增加明显,与阳性对照组差异有统计学意义(P<0.05)。扁桃酸各剂量组对小鼠耳肿胀的影响无显著作用,与空白对照组比较差异无统计学意义(P>0.05)。结论:扁桃酸具有显著的镇痛作用,抗炎作用不明显。