Numerical investigation of friction-heating-pressurization and its control parameters in the shear band of high-speed landslides

High-speed sliding often leads to catastrophic landslides,many of which,in the initial sliding phase before disintegration,experience a friction-induced thermal pressurization effect in the bottom shear band,accelerating the movement of the overlying sliding mass.To quantitatively investigate this complex multiphysical phenomenon,we established a set of equations that describe the variations in temperature and excess pore pressure within the shear band,as well as the conservation of momentum equation for the overlying sliding mass.With a simplified landslide model,we investigated the variations of temperature and excess pore pressure within the shear band and their impacts on the velocity of the overlying sliding mass.On this basis,we studied the impact of seven key parameters on the maximum temperature and excess pore pressure in the shear band,as well as the impact on the velocity of the overlying sliding mass.The simulation results of the standard model show that the temperature and excess pore pressure in the shear band are significantly higher than those in the adjacent areas,and reach the maximum values in the center.Within a few seconds after the start,the maximum excess pore pressure in the shear zone is close to the initial stress,and the shear strength loss rate exceeds 90%.The thermal pressurization mechanism significantly increases the velocity of the overlying sliding mass.The results of parameter sensitivity analysis show that the thermal expansion coefficient has the most significant impact on the temperature and excess pore pressure in the shear band,and the sliding surface dip angle has the most significant impact on the velocity of the overlying sliding mass.The results of this study are of great significance for clarifying the mechanism of thermal pressurization-induced high-speed sliding.

Extraction Fuzzy Linguistic Rules from Neural Networks for Maximizing Tool Life in High-speed Milling Process

In metal cutting industry it is a common practice to search for optimal combination of cutting parameters in order to maximize the tool life for a fixed minimum value of material removal rate（MRR）. After the advent of high-speed milling（HSM） pro cess, lots of experimental and theoretical researches have been done for this purpose which mainly emphasized on the optimization of the cutting parameters. It is highly beneficial to convert raw data into a comprehensive knowledge-based expert system using fuzzy logic as the reasoning mechanism. In this paper an attempt has been presented for the extraction of the rules from fuzzy neural network（FNN） so as to have the most effective knowledge-base for given set of data. Experiments were conducted to determine the best values of cutting speeds that can maximize tool life for different combinations of input parameters. A fuzzy neural network was constructed based on the fuzzification of input parameters and the cutting speed. After training process, raw rule sets were extracted and a rule pruning approach was proposed to obtain concise linguistic rules. The estimation process with fuzzy inference showed that the optimized combination of fuzzy rules provided the estimation error of only 6.34 m/min as compared to 314 m/min of that of randomized combination of rule s.

Breaking and Characteristics of Ganoderma Lucidum Spores by High Speed Entrifugai Shearing Pulverizer

The spores of Ganoderma lucidum were ground and broken to ultrafine particles by high speed centrifugal shearing（HSCS） pulverizer. The characteristics of Ganoderma lucidum spores were analyzed by scanning electron microscope （SEM）, Fourier transform infrared spectrophotometry （FTIR）. Ultraviolet-visible pectrophotometer was used to determine the extraction ratio of aqueous solubility polysaccharide between the raw and broken spores. The immunological function on the mice before and after the breaking of spores wan investigated. The experimental results show that after being ground, the sporoderm-broken ratio reachs 100%, the original active ingredients of ganoderma lucidum spores do not change, and the extraction ratio of aqueous solubility polysaccharide is greatly increased by 40.08%. The broken spores show much higher immunological activity comparing with original spores of Ganoderma lucidum.

Pneumomediastinum and subcutaneous emphysema secondary to dental extraction:Two case reports

BACKGROUND Dental extraction is a common operation in oral surgery and is usually accompanied by pain,swelling,and local infection.The application of high-speed air turbines increases the comfort of alveolar surgery and makes it more minimally-invasive.However,high-speed gas can enter the subcutaneous tissue of the face and neck or even the chest and mediastinum,which is a serious iatrogenic complication.CASE SUMMARY We describe two cases of severe subcutaneous and mediastinal emphysema caused by high-speed turbine splitting during dental extraction.The first case involved a 34-year-old man who complained of swelling of the face,mild chest tightness,and chest pain after dental extraction.Computed tomography(CT)scan showed a large amount of gas in the neck,chest wall,and mediastinum.The second case involved a 54-year-old woman who complained of swelling and pain of the neck after dental extraction.CT showed a large amount of gas collected in the neck and mediastinum.Both of them used high-speed turbine splitting during dental extraction.CONCLUSION High-speed turbine splitting during dental extraction may lead to severe subcutaneous and mediastinal emphysema.Dentists should carefully operate to avoid emphysema.If emphysema occurs,CT can be used to improve the diagnosis.The patient should be informed,and the complications dealt with carefully.

Effects of Different Wall-breaking Methods on Extraction of Solanesol from Stems and Leaves of Potato

In order to extract solanesol from potato stems and leaves more effectively and improve the extraction rate of solanesol, the same batch of potato stems and leaves harvested from Guyuan, Ningxia was selected as a research object, cell wall of potato stems and leaves was broken by enzymolysis with cellulase and high- speed shearing, and then reflux-extracted with 95% ethanol. Solanesol content was determined by HPLC, and extract yield was calculated. Extract yield and solanesol extraction rate was used as an index for comparison of difference between the 2 wall-breaking methods, so as to select the optimal wall-breaking method. The results showed that enzymolysis with cellulase exhibited extraction rate and extract yield of solanesol of 91.38% and 8.02%, respectively, which were better than those under high-speed shear emulsification technique. The enzymolysis wall-breaking method has the advantages of simple operation and strong feasibility.

剪切强化碳化法制备电池级碳酸锂工艺研究

针对传统碳化分解法制备电池级碳酸锂存在生产周期长、二氧化碳利用率低、杂质含量难以达到电池级碳酸锂标准等问题,以低品位锂云母矿石浸出液为原料,研究了碳酸钠沉锂—剪切碳化—离子交换—加热分解工艺制备电池级碳酸锂。结果表明:在温度30℃、液固体积质量比25/1、二氧化碳通入速率0.5 L/min、剪切转速6000 r/min条件下,钙、镁、锰去除率分别达97.26%、81.82%、95.73%。剪切辅助碳化法可显著提升碳化反应速率,缩短反应时间,节省70%以上CO 2气体,更有利于制得电池级碳酸锂。所制备碳酸锂符合电池级碳酸锂标准。

Pressure shear assisted extraction of polysaccharide from Auricularia auricula and its biological activities

In this paper,using to the comprehensive scoring method,pressure shear assisted extraction was used to prepare polysaccharide from Auricularia auricula(PS-AAP)by orthogonal test to optimize the extraction.The highest comprehensive score(90.70)was obtained under 1:70 g/mL solid-liquid ratio,110°C reaction temperature,60 min reaction time and 1.0 MPa reaction pressure.Compared to AAP by water bath(WB-AAP),PS-AAP led to a higher extraction efficiency and decreased the relative molecular weight.In addition,infrared spectrum(FT-IR)analysis showed that pressure shear assisted did not change the polysaccharide structure.Scanning electron microscope(SEM)showed that PS-AAP was smaller and more broken by pressure shear assisted.Furthermore,the ratio of glucose to mannose in PS-AAP was relatively higher than WB-AAP,which also proved that PS-AAP had certain antioxidant and hypoglycemic activities.Compared with WB-AAP,the inhibitionα-glucosidase andα-amylase activity of PS-AAP increased by 11.37%and 24.43%respectively.These results revealed that PS-AAP has the poten-tial value of being a antioxidant and hypoglycemic agent.

Rheology study of supercritically extracted tea-oil

The rheological analysis on dynamic shear rate-viscosity relationship of tea-oil extracted from tea-oil tree seeds by supercritical extraction method was carried out at gradient temperatures and constant shear rate,respectively.The results show that at 20,40,60 and 80 ℃,once the shear rate increases gradually,the torque enlarges correspondingly,while the viscosity shows little difference.However,at the constant shear rate,the rising temperature results in a steady downtrend on tea-oil viscosity.This results reveal that tea-oil viscosity is not closely correlated with shear rate at constant temperature,yet negatively correlated with temperature at constant shear rate.

Measurement of high-dynamic temperature field using high-speed quadriwave lateral shearing interferometer

An approach to measure a high-dynamic two-dimensional(2 D) temperature field using a high-speed quadriwave lateral shearing interferometer(QWLSI) is proposed. The detailed theoretical derivation to express the wavefront reconstruct principle of the proposed method is presented. The comparison experiment with thermocouples shows that the temperature field measurement using QWLSI has a precision of ±0.5 °C. An experiment for measuring the highdynamic temperature field generated by an electrical heater is carried out. A 200 frame rate temperature field video with 512 × 512 resolution is obtained finally. Experimental results show that the temperature field measurement system using a QWLSI has the advantage of high sensitivity and high resolution.

Failure mode change and material damage with varied machining speeds:a review

High-speed machining(HSM) has been studied for several decades and has potential application in various industries, including the automobile and aerospace industries. However,the underlying mechanisms of HSM have not been formally reviewed thus far. This article focuses on the solid mechanics framework of adiabatic shear band(ASB) onset and material metallurgical microstructural evolutions in HSM. The ASB onset is described using partial differential systems. Several factors in HSM were considered in the systems, and the ASB onset conditions were obtained by solving these systems or applying the perturbation method to the systems. With increasing machining speed, an ASB can be depressed and further eliminated by shock pressure. The damage observed in HSM exhibits common features. Equiaxed fine grains produced by dynamic recrystallization widely cause damage to ductile materials, and amorphization is the common microstructural evolution in brittle materials. Based on previous studies, potential mechanisms for the phenomena in HSM are proposed. These include the thickness variation of the white layer of ductile materials. These proposed mechanisms would be beneficial to deeply understanding the various phenomena in HSM.

双边剪钢板自动对中系统研究

双边剪切工艺中钢板对中过程需要人工目视激光线进行余量观测,操作复杂且主观判断影响数据准确性。为此设计基于机器视觉的双边剪钢板自动对中系统,依赖沿辊道分布的多组面阵相机进行辊道钢板状态数据采集,利用现场测量数据及钢板目标宽度标定出两条虚拟剪切线,摆脱对传统辅助激光线的依赖。同时系统中采用级联的钢板对象提取模型,采用先粗后精的分步提取思想,提升钢板边缘检测精度。依据钢板轮廓位置与虚拟剪切线位置关系换算出移动距离,从而控制磁力对中装置完成钢板对中过程,提升双边剪工艺的自动化程度。实际应用结果表明,系统对于钢板宽度测量误差小于5 mm,系统自动控制对中误差小于10 mm,满足企业自动控制需求。

平纹SiC纤维织物剪切性能

SiC纤维织物是耐高温陶瓷基复合材料的一种重要增韧材料。本文以平纹SiC纤维织物为研究对象,开展了单轴拉伸试验和±45°偏轴拉伸试验,得到了其拉伸和剪切性能;进行了纱线抽出试验,得到其经纬纱线间的摩擦系数;通过X射线CT检测,得到其细观结构;利用最小二乘法拟合出经纬纱线的横截面和卷曲形状曲线;通过建立纱线的简支梁模型,计算出剪切变形中经纬纱线摩擦力矩,预测了平纹SiC纤维织物的剪切应力-应变曲线。剪切变形过程分为纯剪和纱线挤压阶段,两个阶段的交界点为织物的锁紧角。研究结果对设计和制备平纹SiC纤维织物预制体具有参考价值。

灵芝总甾醇的闪式提取工艺优化及其抗氧化活性

采用高速剪切闪式提取技术从灵芝中提取总甾醇。GC-MS分析表明:灵芝总甾醇提取物中主要含有麦角甾醇和麦角甾-7,22-二烯-3β-醇。通过单因素实验和响应面实验优化提取工艺,在剪切机转速8 400 r/min、液料比25∶1(mL∶g)、剪切时间9 min的最优条件下,麦角甾醇实际得率为0.072 1%。对灵芝总甾醇提取物进行了抗氧化活性的测定,V C做阳性对照,灵芝总甾醇(以麦角甾醇计)浓度为1mg/mL时,对DPPH·的清除率达95.16%,对ABTS+·的清除率达81.33%,对·OH的清除率达55.41%,还原力吸光度为1.746。

高速剪切与微波辅助偶联提取鲜葛中葛根素

以湘西野葛根为原料,经高速剪切破坏其组织细胞,偶联微波辅助提取其葛根素。实验探讨剪切时间、剪切速度、微波平均辐射功率、辐射时间对葛根素提取率的影响。并采用响应面法试验设计,确定其最佳提取工艺。实验结果表明最佳工艺参数为剪切时间6min,剪切速度6000r/min,微波辐射时间20s,微波功率467.27W,获取葛根素含量2.05mg/g。

黑木耳多糖高剪切分散乳化法与酶法提取的比较研究

以黑木耳多糖得率为指标,分别采用高剪切分散乳化法和酶法提取黑木耳多糖,并对提取效果进行比较。结果表明:高剪切分散乳化法提取黑木耳多糖的工艺条件为转速21 000r/min,料液比1110(m/V),时间6 min,温度80℃;酶法提取黑木耳多糖的工艺条件为酶添加量1.2%,酶解时间60min,pH 5.5,酶解温度55℃,二者得率分别为24.43%,9.29%。与酶法相比,高剪切分散乳化法提取黑木耳多糖得率高、提取时间短、操作简单。故高剪切分散乳化法是黑木耳多糖提取的一种适宜方法。

基于信号特征提取的电阻点焊质量在线评判

以焊点接头强度作为焊点质量评判的指标,通过对点焊过程焊接电流、动态电阻、电极位移信号的同步采集和特征分析,提取若干特征参量监测点焊过程,依据特征参量与焊点接头抗剪强度间的相关分析结果,选取来自不同监测信号的7个特征参量建立了表征点焊过程的特征模式,并将此转化为计算机可以识别的模式矩阵,同时以焊接电流参数为模式分类的依据,建立不同模式矩阵类别和焊点接头抗剪强度之间的映射,将模式矩阵作为Hopfield神经网络的记忆样本存储于网络,利用网络联想记忆的功能实现对未知样本点焊过程的模式识别,进而实现点焊质量的评判。网络测试结果表明,利用Hopfield网络进行焊点质量在线评判可以得到满意的效果。

响应面法优化高剪切分散乳化提取悬钩子多酚

为探究提取小浆果悬钩子中活性成分多酚的最佳工艺参数,采用高剪切分散乳化提取技术,探讨了提取溶液浓度,高剪机转速,剪切时间3个因素对悬钩子多酚提取含量的影响。在单因素水平分析基础上,运用响应面优化设计试验对提取工艺进一步优化,由Design-Expert 7.0.0软件分析确定了悬钩子多酚的最佳提取条件,考虑到实际操作的便利,将最佳工艺参数修正为:提取溶液体积分数:85%,高剪机转速:18 000 r/min,剪切时间:220 s。经验证试验证实,优化后悬钩子提取物中多酚质量分数为(713.89±0.66)mg/hg鲜果。总黄酮和花色苷的质量分数分别为(229.97±1.37)mg/hg鲜果和(28.75±0.43)mg/hg鲜果。与传统的超声波、微波等辅助提取法相比,高剪切分散乳化技术提取法大大缩短了提取时间,避免了有效成分的损失与变性,是一种极具应用前景的方法。

酵母(Saccharomyces cerevisiae)及酵母提取物对肉鸡肉质的影响(英文)

本文旨在研究酵母(Saccharomyces cerevisiae)及其提取物对肉鸡肉质的影响。试验采用单因子随机分组,选取1日龄雄性肉鸡180只,随机分为3组,每组6个重复,每个重复10只。分别在基础饲粮中添加0.5%酵母和0.3%酵母提取物作为试验组饲粮。试验结果表明,饲粮添加酵母提取物可显著增加肉鸡小腿肉的最终pH(P<0.05),同时饲粮添加酵母有增加肉中水分含量及降低水煮失重率的趋势,但未达到统计学显著水平(P>0.05)。饲粮添加酵母及酵母提取物与对照组相比均可显著降低生肉和熟肉的剪切力(P<0.05)。饲粮添加酵母与对照组相比可显著降低TBARS值(P<0.05)。由此可知,饲粮添加酵母及酵母提取物可改善肉鸡肉质和嫩度,同时酵母及酵母提取物均具有降低氧化的作用。

高剪切乳化技术在柚子皮总黄酮提取中的应用

以柚子皮为原料,经过高剪切处理之后,用乙醇提取柚子皮中总黄酮。通过单因素试验,测定在不同条件下的黄酮提取率。得到最优的提取条件为:提取温度70℃,提取时间1.5 h,乙醇溶剂浓度80%,液料比40∶1,高剪切次数7次,剪切转速16000 r/min,剪切温度50℃。在优化条件下得到的黄酮提取率为0.902%。相比未进行剪切处理的样品,提取率增加了12.6%,表明高剪切处理是提高黄酮提取率的有效途径,另外,提取物有较强的抗氧化效果。

一种治疗哮喘复方中药颗粒剂不同制粒工艺的比较

目的比较治哮喘复方中药颗粒剂的3种制剂工艺,评价不同制粒工艺优缺点。方法以外观、流动性、粒径分布、吸湿性和溶化时间为指标评价湿法制粒、流化床一步法制粒,高速剪切制粒3种制粒工艺制得颗粒的优劣。结果流化床一步制粒法制粒工艺简单,制得颗粒的外观、流动性、粒径分布和溶化性均优于湿法制粒和高速剪切制粒,仅吸湿性稍差。结论综合考虑各个指标,3种工艺制得的颗粒中以流化床一步法制得颗粒最好。