生物防治研究进展

生物防治是农作物病虫害防治技术中一门传统应用科学,随着可持续生态农业重要思想的提出,生物防治越来越受到人们的重视.本文就生物防治的研究现状,从研究概况,研究进展,存在问题及今后研究方向三个方面来介绍当前生物防治发展状况.     

电刺激干预腓肠肌拉伤后成肌调节

目的：采用低强度电刺激治疗腓肠肌拉伤,观察其对于肌肉损伤部位成肌调节因子MyoD与Myogenin蛋白表达的影响。方法：雄性SD大鼠32只,随机分为对照组、模型组、D14组和D14-40Hz组。除对照组外其余各组建立腓肠肌拉伤动物模型。于造模后第5天D14-40Hz组开始予以电刺激,其余组继续喂养。正常对照组在实验开始当天,模型组在造模当天,D14组和D14-40Hz组在第14天进行在体力矩测试,测试结束后处死动物,分离腓肠肌采用免疫印迹法（Western blotting）测定MyoD与Myogenin蛋白表达。结果：对照组关节最大等长力矩值为0236±0045（Nm）,模型组肌肉拉伤后即刻关节最大等长力矩下降为0176±0034（Nm）,两者比较存在显著性差异（P＜005）;第14天D14-40Hz组最大等长力矩值为0247±0038（Nm）,与D14组比较存在显著性差异（P＜005）。MyoD与Myogenin蛋白表达测定结果：肌肉拉伤后第14天MyoD蛋白表达D14组与对照组比较无差异（P＞005）,但是MyoD蛋白表达D14-40Hz组比D14组增强明显（P＜005）;肌肉拉伤后第14天,D14-40Hz组Myogenin蛋白表达明显强于D14组（P＜005）。结论：腓肠肌急性拉伤后,早期采用低强度电刺激治疗可以明显提高关节力矩,并促进了MyoD与Myogenin的表达,对组织修复起到了积极地作用。     

基于变论域模糊PID的温度控制

针对弹丸应变实验系统温度8控制过程中具有非线性、大时滞及温度难以精确控制等问题,引入变论域思想,利用变论域思想的伸缩因子改变控制系统模糊规则的论域,结合PID控制和模糊PID控制的优点,从而形成变论域模糊PID自适应温度控制系统,设计了变论域模糊PID的温度控制方法。利用MATLAB仿真结果标明:与模糊PID算法比较,变论域模糊PID温度控制算法在超调量、鲁棒性和动态响应速度方面均具有明显优势。     

基于应变片法的低温条件下热膨胀特征参数的测量方法与装置

研究目的：为了满足低温系统的材料选择和结构设计对于材料热膨胀特征参数的需求,研发低温条件下精确、快速、方便操作、低成本的热膨胀特征参数测量方法和系统装置。创新要点：完成了卡玛合金箔应变片在77-293K低温温区敏感系数的修正,保证了基于应变片技术的低温条件材料热膨胀特征参数测量的精度;所研制装置合理的热设计和等速率式温度控制模式使得材料热膨胀特征参数在77-293K温区的测量可在14小时内快速完成。研究方法：针对77-293K温区,基于应变片测量方法,研制了采用比例-积分-微分（PID）温控系统的固体材料热膨胀特征参数测量装置（见图2和3）。通过将304不锈钢的测量数据与美国国家标准与技术研究院（NIST）公布数据进行比较,完成了卡玛合金箔应变片存77-293K低温温区的敏感系数修正（见图7和8）。采用修正后的敏感系数进行无氧铜线性收缩率测量,并与NIST公布数据比较（见图9和表2）,验证了该装置在77-293K低温温区的测量精度。重要结论：获得了77-293K低温温区卡玛合金箔应变片敏感系数的修正结果;基于修正敏感系数的应变片法测量装置,采用0．3K／min的等速率式温度控制模式,可实现77-293K低温温区固体材料热膨胀特征参数的精确、快速测量。     

应用神经肌肉电刺激技术发展女子赛艇运动员腰背肌力量

为了探索神经肌肉电刺激技术在赛艇运动训练中的实际应用,我们对浙江女子赛艇队的6名队员进行了为期6周的实验研究,其中3人以治疗腰肌劳损为主要目的,另3人以发展背阔肌力量为目的。经与同期进行正常训练不接受电刺激的对照组8人比较,发现实验组的力量训练效果皆优于对照组,且腰肌劳损组的平均最大卧拉力增长大于背阔肌组。     

Exploring the influence of excessive social media use at work: A three-dimension usage perspective

Pervasive social media has resulted in technology dependency and excessive usage, which can lead to negative outcomes in organizations. This paper aims to investigate the effects of social media’s different excessive usage patterns on employee job performance and the corresponding underlying mechanism. Specifically, we propose three dimensions of excessive social media use at work (i.e., excessive social, hedonic, and cognitive). These dimensions are related to technology-work conflict and strain, which in turn decrease employee job performance. An empirical study of 305 social media users in organizations reveals that excessive social media use for socialization and entertainment can generate conflict between technology use and work demand, whereas excessive social media use for information-sharing reduces employees’ psychological strain. In addition, technology-work conflict and strain negatively influence job performance. The theoretical and practical implications of this study are also discussed.     

Morphology evolution of two-phase Cu-Ag alloys under different conditions

Cu-Ag filamentary microcomposites with different Ag contents were prepared by cold drawing and intermediate heat treatments. The microstructure characterization and filamentary distribution were observed for two-phase alloys under different conditions. The effect of heavy drawing strain on the microstructure evolution of Cu-Ag alloys was investigated. The results show that the microstructure components consist of Cu dendrites, eutectic colonies and secondary Ag precipitates in the alloys containing 6%-24% （mass fraction） Ag. With the increase in Ag content, the eutectic colonies in the microstructure increase and gradually change into a continuous net-like distribution. The Cu dendrites, eutectic colonies and secondary Ag precipitates are elongated in an axial direction and developed into the composite filamentary structure during cold drawing deformation. The eutectic colonies tend to evolve into filamentary bundles. The filamentary diameters decrease with the increase in drawing strain degree for the two-phase alloys, in particular for the alloys with low Ag content. The reduction in filamentary diameters becomes slow once the drawing strain has exceeded a certain level.     

液化气罐工作应力测量和评估

为了评估局部受损液化气罐的应力水平,利用气压试验对罐体进行加载,采用电测法对罐体缺陷区、封头焊缝热影响区和母材区的应力进行测定。结果表明,凹坑区域呈现出较高的应力水平,最大应力位于凹坑中心,为436 MPa(1.12 Rel),该区域的高应力水平在湿H2S腐蚀环境中易引发局部应力腐蚀;受焊接残余应力的影响,罐体总应力有可能进一步增加;罐体继续使用前应对变形部位进行局部消除残余应力热处理,罐体内部定期进行表面探伤。     

《冲压工艺学》圆筒拉深过程应力应变状态分析授课探讨

圆筒形件的应力应变分析对于应对实际生产中可能出现的各种缺陷至关重要,在实际授课过程中,学生普遍反映该部分理解起来较为抽象,相关教材中也存在不尽完善之处。文章通过理论分析对圆筒形件拉深过程进行分析,不仅完善了相关教学理论,使学生接受起来更加容易,并且根据实际教学总结相关口诀,使得关键知识点更加易于记忆。     

An appraisal of techniques and equipment for cutting force measurement

INTRODUCTION Metal machining processes are characterised mainly by quick changes in quantified elements. In- dividual changes do not occur in isolation and they influence each other. The analysis of these changes require study of the complicated complete systems in their real situations. The study of cutting processes such as turning and facing, from dynamic aspects, is very important. The trend towards the measurement of cutting forces in machining leads to many theo- retical and practic…