工艺参数对球墨铸铁和低碳钢激光焊接的影响

为了提高球墨铸铁和低碳钢焊接接头力学性能,解决容易开裂的问题,采用激光焊接的方法对球墨铸铁和低碳钢进行焊接,研究了工艺参数对其焊接接头的组织和性能影响。结果表明,随着激光功率逐渐增加或焊接速率的逐渐变缓,试验件抗拉强度呈现出先增大后减小的变化趋势;当焊接功率为4250 W和焊接速率为2.4 m/min时,试样件焊接接头的强度处于极值400 MPa;在球墨铸铁侧热影响区内形成3种壳体结构(双壳结构、单壳结构和无核结构);焊缝区组织主要由树枝晶组织、少量的马氏体和莱氏体组织构成;焊缝区存在微裂纹,通过添加镍基材料可获得无裂纹焊缝,并提升抗拉强度约40 MPa,达到母材的95%。该研究对后续球墨铸铁与低碳钢高功率激光焊接工艺优化是有帮助的。

移动式防洪墙模型系统整体力学性能测试

研究了在正常蓄水条件下2.4m高及4m高移动式防洪墙模型系统整体的力学性能。在试验场地用混凝土墙及移动式防洪墙围建扇形和方形试验系统,用缓慢蓄水过程来模拟移动式防洪墙在真实工况条件下抵挡洪水的过程。用拉线式位移计、应变片等来监测移动式防洪墙的位移特征。结果表明:随着蓄水高度的增加,立柱和挡板的应力和变形不断增加,立柱的危险点在立柱主体和加强件的过渡位置,挡板的危险点为从下往上数第二、第三块挡板的中部,上述危险点为影响防洪墙力学性能的关键位置。

基于主要环境因子的设施黄瓜生长模型研究

针对当前设施黄瓜种植管理标准化程度低,作物生长过程中环境因素难以精准调控等问题,以德州市陵城区秋冬茬设施黄瓜为试验材料,利用主成分分析、多重共线性分析和岭回归组合算法构建基于主要环境因子的设施黄瓜生长模型。结果表明:(1)在株高、茎粗、叶片数、叶面积等生长指标中,苗期和初花期的叶面积载荷值在第一主成分中分别为0.994、0.980,说明叶面积能够较明显的表现黄瓜苗期和初花期的生长状况;(2)苗期影响叶面积变化的主要环境因素为光照、温度和湿度,初花期影响叶面积变化的主要环境因素为温度和光照,且都为正向显著影响;(3)基于岭回归建立的不同时期设施黄瓜生长模型,其模型决定系数皆大于90%。研究构建的生长模型具有较强的针对性,为科学选取代表黄瓜苗期和初花期长势的指标提供较好的方向,也为设施黄瓜种植者调控生产环境提供参考依据。

矿渣掺量对热养护粉煤灰基地聚物收缩和抗压强度的影响及机理分析

本文通过数字图像相关(DIC)方法研究了0%、10%、20%、30%、40%、50%六种矿渣掺量(质量分数,下同)对粉煤灰基地聚物(FAGP)混凝土热养护过程中收缩的影响,测试了热养护后混凝土和净浆的抗压强度,并且结合同步热分析(TGA-DSC)、X射线衍射(XRD)和扫描电子显微镜(SEM)对微观机理进行了分析。结果表明:随着矿渣掺量的增加,FAGP的收缩量和收缩速率均先减小后增大,抗压强度先增大后减小,水化程度增大,微裂缝数量增加;当矿渣掺量为40%时,FAGP混凝土的收缩量最小,抗压强度最大;当矿渣掺量较低时,地聚物水化程度小,微裂缝少,地聚物收缩的主要原因是热养护初期的弹性模量较低;当矿渣掺量较高时,地聚物水化程度大,微裂缝较多,地聚物收缩主要由较强烈的化学反应引起。

先锋派建筑审美变革背后的阶层诉求

在工业革命导致欧洲社会变革和阶层流动的社会背景下,以布尔迪厄关于阶层区分中审美配置的研究为理论基础,从20世纪初建筑先锋派运动宣言与实践的自我矛盾现象出发,阐释了建筑先锋派运动的首要目标是打破作为社会主流的传统建筑审美束缚;技术性、经济性、适用性等宣言在当时更多是为现代建筑审美提供合法性说辞。通过分析先锋派建筑师反传统审美背后对主流资产阶层审美品位的鄙视以及对获得资本权力认可的渴望,认为先锋派建筑师为现代建筑审美发声的一个非常重要的目的是:实现自我的阶层诉求,成为新的工业时代下资产阶层中牢固的一分子。

Simultaneous Determination of Melamine, Ammelide, Ammeline, and Cyanuric Acid in Milk and Milk Products by Gas Chromatography-tandem Mass Spectrometry

Objective To develop an analytical method for simultaneously qualitative and quantitative determination of melamine and triazine-related by-products including ammelide, ammeline, and cyanuric acid in milk and milk products by gas chromatography- tandem mass spectrometry （GC-MS/MS）. Methods Melamine and triazine-related by-products namely ammelide, ammeline and cyanuric acid in the samples were extracted in a solvent mixture of diethylamine, water, and acetonitrile （10：40：50, V/V/V）. After centrifugation, an aliquot of the supernatant was evaporated to dryness under a gentle stream of nitrogen gas, and then melamine and triazine-related by-products were derivatized using BSTFA with 1% TMCS. The derivatives of melamine and its analogues were determined by gas chromatography/tandem mass spectrometry using multiple reactional monitoring （MRM） with 2, 6-Diamino-4-chloropyrimidine （DACP） being used as an internal standard. Results The linear detectable ranges were from 0.004 mg/kg to 1.6 mg/kg for melamine, ammelide, ammeline, and cyanuric acid with a correlation coefficient no less than 0.999. The recovery rates of the tour compounds in spiked blank milk powder at concentrations 0.5, 1, 2 mg/kg were between 61.4%-117.2%, and the relative standard deviation was no more than 11.5% （n=6）. The detection limits of melamine, ammelide, ammeline and cyanuric acid in milk powder were 0.002 mg/kg with a ratio of signal to noise of 3. Conclusion This GC-MS/MS method for simultaneous determination of melamine, ammelide, ammeline, and cyanuric acid in milk and milk products is sensitive and specific.

Mechanisms underlying attenuation of apoptosis of cortical neurons in the hypoxic brain by flavonoids from the stems and leaves of Scutellaria baicalensis Georgi

Flavonoids from the stems and leaves of Scutellaria baicalensis Georgi, an antioxidant, markedly improve memory impairments and neuronal injuries. In the present study, primary cortical neurons of rats were exposed to potassium cyanide to establish a model of in vitro neural cell apoptosis. Inhibition of apoptosis by flavonoids from the stems and leaves of Scutellaria baical- ensis Georgi at concentrations of 18.98, 37.36, and 75.92 gg/mL was detected using this model. These flavonoids dramatically increased cell survival, inhibited cell apoptosis and excessive pro- duction of malondialdehyde, and increased the activities of superoxide dismutase, glutathione peroxidase, and Na＋-K＊-ATPase in primary cortical neurons exposed to potassium cyanide. The flavonoids from the stems and leaves of Scutellaria baicalensis Georgi were originally found to have a polyhydric structure and to protect against cerebral hypoxia in in vitro and in vivo models, including hypoxia induced by potassium cyanide or cerebral ischemia. The present study suggests that flavonoids from the stems and leaves of Scutellaria baicalensis Georgi exert neuroprotective effects via modulation of oxidative stress, such as malondialdehyde, superoxide dismutase, glutathione peroxidase and Na＋-K＋-ATPase disorders induced by potassium cyanide.

Flavonoids from Scutellaria baicalensis Georgi are effective to treat cerebral ischemia/reperfusion

Based on previous studies that have shown flavonoids from the stems and leaves of Scutellaria baicalensis Georgi are neuroprotective agents in a naturally senile, D-galactose, aging in vivo model, as well as an in vitro model of oxidative/hypoxic injury, we established a cerebral ischemia/reperfusion model in rats by middle cerebral artery occlusion. The light/electron microscopic observations found significant neuropathological changes including neuron loss or swelling and rough endoplasmic reticulum injury. Moreover, the activities of lactate dehydrogenase Na＋-K＋-ATPase, Ca2＋-ATPase and superoxide dismutase were significantly lowered, and the levels of malonaldehyde increased. In addition, the memory of rats worsened. However, treatment with flavonoids from Scutellaria baicalensis Georgi （35, 70 and 140 mg/kg） for 13 days dramatically improved the above abnormal changes. These results suggest that the ability of flavonoids from Scutellaria baicalensis Georgi in attenuating cerebral functional and morphological consequences after cerebral ischemia/reperfusion may be beneficial for the treatment of ischemic brain disease.

Direct conversion of fructose-based carbohydrates to 5-ethoxymethylfurfural catalyzed by AlCl_3·6H_2O/BF_3·(Et)_2O in ethanol

Direct conversion of fructose-based carbohydrates to 5-ethoxymethylfurfural （EMF） catalyzed by Lewis acid in ethanol was investigated. It was found that BF3.（Et）20 was favorable for 5-hydroxymethylfurfural （HMF） etherification to EMF. BF3.（Et）20 combination with A1C13.6H20 with the molar ratio of 1 was an effective catalyst system for synthesis of EMF from fructose-based carbohydrates. 55.0%, 45.4% and 23.9% of EMF yields were obtained from fructose, inulin and sucrose under optimized conditions, respectively.

A convenient look-up-table based method for the compensation of non-linear error in digital fringe projection

Although the structured light system that uses digital fringe projection has been widely implemented in three-dimensional surface profile measurement, the measurement system is susceptible to non-linear error. In this work, we propose a convenient look-up-table-based （LUT-based） method to compensate for the non-linear error in captured fringe patterns. Without extra calibration, this LUT-based method completely utilizes the captured fringe pattern by recording the full-field differences. Then, a phase compensation map is established to revise the measured phase. Experimental results demonstrate that this method works effectively.

Present Situation of the Anti-Fatigue Processing of High-Strength Steel Internal Thread Based on Cold Extrusion Technology:A Review

The adoption of cold-extrusion forming for internal thread net forming becomes an important component of anti-fatigue processing with the development of internal thread processing towards high performance, low cost and low energy consumption. It has vast application foreground in the field of aviation, spaceflight, high speed train and etc. The internal thread processing and anti-fatigue manufacture technology are summarized. In terms of the perspective of processing quality and fatigue serving life, the advantages and disadvantages of the processing methods from are compared. The internal thread cold-extrusion processing technology is investigated for the purpose of improving the anti-fatigue serving life of internal thread. The superiorities of the plastic deformation law and surface integrity of the metal layer in the course of cold extrusion for improving its stability and economy are summed up. The proposed research forecasts the develop- ment tendency of the internal thread anti-fatigue manufacturing technology.

基于STM32的滑块式油水分离装置设计及测试

随着石化工业的快速发展,炼油工艺下游含油污水的大量排放不但会造成环境污染,而且由于油品的易燃特性,遇明火易造成火灾。该文设计了一种基于STM32的滑块式油水分离装置,利用油水介质的导电性差异及超声波全反射原理,智能识别油气水三相,自动进行油水分离操作;并利用远程监控组件实现PC端油水分离状态及温度、气压等参数的实时监控。相比于传统的重力、过滤分离法等,自动化程度高,油水分离效果好,加强了安全系数。

VR技术在城乡规划领域应用现状和展望

虚拟现实(VR)技术为使用者提供模拟现实的操作环境,使其产生身临其境的现场感,VR技术正逐步应用于城乡规划与设计领域。文章通过分析现有的相关文献,从VR技术在产业发展中的应用探索、交互性规划设计中的应用、人本尺度规划研究支持3个角度进行梳理,总结VR技术应用于城乡规划领域的研究现状与问题,并提出3个方面的研究展望。

从宗教伦理的角度解读日本传统建筑观

针对日本传统建筑观中截然不同于西方和中国传统建筑观的特征,如喜好自由布局、质朴审美、讲求建筑的实用性等,运用马克斯·韦伯宗教社会学的分析方法,从建筑的象征、审美和使用三个方面,分析了日本传统宗教伦理对传统建筑观的影响,包括政教权力的分立对建筑象征性的影响,武士道的禁欲主义对建筑审美的影响,以目标为核心的价值观对建筑用途与形式关系的影响,指出了日本传统社会独特的建筑观与其宗教伦理关系密切,宗教伦理塑造了一个社会的精神气质,进而深刻影响了建筑观的形成。

Inhibition of Flavonoids from Scutellaria baicalensis Stems and Leaves against Abnormal Formation of PHF and Regulation of PP in OA Induced Brain Injury in Rats

[Objectives] To explore the inhibitory effects of flavonoids from Scutellaria baicalensis Georgi stems and leaves against abnormal formation of PHF and regulation mechanism of protein phosphatase(PP) in okadaic acid(OA) induced brain injury in rats.[Methods]Male Sprague-Dawley rats were treated with OA(200 ng/kg) in the lateral ventricle to establish a memory impairment model,and Morris water maze was used to screen the memory impairment model.Rats were intragastrically administered with 25,50 and 100 mg/kg SSF daily for 36 d.The protein expressions of PHF,PP1,PP2A-Cα,PP2A-Cβ,PP2 CA and PP2 CB in rat cortex and hippocampus were determined by Western blot.Ginkgo biloba leaf flavonoids were used as positive control drugs.[Results]Compared with the sham-operated rats,the expression of PHF protein in the cortex and hippocampus of the model group was significantly increased(P < 0.01);protein expression of PP2A-Cα and PP2A-Cβin the cortex and hippocampus,and PP2 CB in the hippocampus were significantly decreased(P < 0.05);protein expression of PP2 CA and PP2 CB in the cortex was significantly increased(P < 0.01);protein expression of PP1 in the cortex was significantly decreased(P < 0.01).Compared with the model rats,25,50 and 100 mg/kg SSF 36 d reversed the protein expression of PHF,PP2A-Cα and PP2ACβ in rat cortex and hippocampus and expression of PP1 in rat cortex induced by OA,but had no significant effect on the protein expression of PP2 CA and PP2 CB,G.biloba flavonoids also showed similar results to SSF.[Conclusions] SSF can significantly inhibit the abnormal formation of PHF in rat brain induced by OA.The inhibitory effect may be related to the regulation of PP1,PP2A-Cα and PP2A-Cβ protein expression in cerebral cortex and hippocampus by SSF,but less related to the regulation of PP2 CA and PP2 CB.

救生伞结构强度两种不同试验方法的开伞动载分析研究

开伞动载是反映救生伞安全救生性能的一项重要战技指标。首先介绍了机载空投和气体炮两种不同的救生伞结构强度试验方法，其次阐述了其工作原理和开伞动载测试方法，最后对获取的开伞动载数据进行了对比分析研究。

工程资产全链管理体系构建——基于国网安徽电力的探索实践

国网安徽电力充分借鉴类脑智能理念,利用“大云物移智链”等新兴技术,建立了基于“一站、三精、五全”的工程资产全链可视管控平台,实现了工程资产全过程精益管理、智能控制,大大提升了财务“支撑战略、支撑决策、服务业务、创造价值、防控风险”能力。本文对国网工程资产全链管理体系的构建思路和具体路径进行了详细阐述,并在此基础上,对相关经验和思考进行总结,为同类型企业工程资产管理提供借鉴和参考。

团体动力学导向下高校班级建设研究

班级建设是高校学生思想政治工作的重要组成部分,针对班级建设中学生容易出现的纪律意识不足、班级凝聚力不够等问题,立足团体动力学的理论基础,明确成长互助小组的组成原则,划分成长互助小组的类型,监控成长互助小组的开展,逐步探究成长互助小组融入班级建设的具体实施阶段、运行步骤、评估及反馈方式,帮助学生在思想、心理、学习、生活等各方面互助互勉,实现个人与团体的共同发展,共同应对大学生活的挑战,从而达到班级建设的目的。

远程会议口译的风险及防范

2020年新冠疫情在全球的爆发使远程会议口译成为常态,这一新常态对口译员、会议组织者、口译服务及设备提供商都带来一定的风险和挑战。本文以一线会议口译员远程同声传译的经验为基础,从口译员的视角,对远程同声传译给口译员带来的五方面风险和挑战进行分析,并提出相应的对策与建议,帮助他们更好地适应这一新的工作模式。

基于数字图像相关技术的轻骨料混凝土早龄期细观收缩实验研究

利用数字图像相关(Digital Image Correlation,DIC)技术,对早龄期轻骨料混凝土(Lightweight Aggregate Concrete,LWAC)在细观层面上的收缩现象开展实验研究,以探索其早龄期的收缩变形规律。具体实验方法为,在3种不同的水灰比条件下,分别比较骨料是否预湿对收缩变形的影响;使用DIC技术对LWAC的收缩变形进行观测,获得LWAC表面早龄期全场应变的演变过程。结果表明,预湿处理能够对轻骨料产生内养护的作用,从而减少混凝土早龄期的收缩变形;随着水灰比的增大,内养护的效果并不会随之增强,而是表现出先升后降的趋势,在水灰比为0.40时内养护效果最佳;在早龄期骨料与砂浆两部分的最小主应变没有表现出始终一致的变化趋势,而是在一定时间段内相互背离。