Study on Large Power Tractor Driver’s Heart Rate and Fatigue in Sowing Work

In order to reduce the driving fatigue in sowing work, this paper based on heart rate (HR) as the main indicator to survey, tested and analyzed the fatigue condition of the drivers of three imported tractors and one domestic tractor in sowing work. The results showed that when driving the imported tractors in sowing work, the HR increasing rate was 10.4%-14.3%, labor intensity belonged to the light level;when driving domestic tractor in sowing work, the HR increasing rate was 23.4%-33.0%, it was remarkably bigger than that of driving imported tractors (P＜0.05), labor intensity belonged to the middle level. The main effects on driving fatigue included the control methods, tractors' cab environment, processing time, operating content, and so on. Finally, we proposed the concrete measures and suggestions to reduce driving fatigue and improve drivers' work condition.     

Application of Time-frequency Representations in Study on Heart Sound

Heart sound is non-stationary signal, some of its important characteristics can be obtained by time - frequency analysis method. The criteria of different time-frequency representation concentricity of spectrogram, coverage, MSE and regularity of time envelope axe proposed, the performances of Short-time Fourier transform, Wigner - Ville distribution, continuous wavelet transform, and S transform in study on heart sound are compared based on these criteria , and concrete example of application is given.     

Stability analysis on shallow tunnel with floor lift under inclined ground by upper bound method

采用极限分析上限法,基于内外能耗守恒原理,通过构建考虑隧底隆起的斜坡地段浅埋隧道破坏模式,推导出围岩压力的计算式,并通过典型算例重点分析了典型因素对隧道围岩稳定性的影响。研究结果表明：基于泰沙基极限平衡法进行隧道围岩支护设计较为保守,不考虑隧底隆起的极限分析方法次之考虑隧底隆起极限分析方法的风险最大;斜坡地表倾角增大对浅埋隧道稳定性有着不可忽视的不利影响;围岩压力随岩土侧压力系数减小、埋深增大、断面尺寸加大而增大;岩土黏聚力增大、内摩擦角增大对提高浅埋隧道围岩稳定性有积极作用。     

矿粉粒度及反应温度对高磷鲕状赤铁矿制备碳化铁的影响

基于对50根弯曲破坏钢筋混凝土圆柱低周反复试验结果的分析,建立了完整滞回环的数学表达式并推导得出等效阻尼比计算模型;以双柱墩桥梁为例,说明了建立桥梁整体结构等效阻尼比与墩柱端部塑性铰等效阻尼比关系的方法。研究表明,完整滞回环数学表达式较好地反映了弯曲破坏钢筋混凝土圆柱的滞回特性,得到的等效阻尼比模型计算结果与试验结果符合较好;采用建立的桥梁整体结构等效阻尼比与墩柱端部塑性铰等效阻尼比的关系进行pushover分析更能反映实际情况。采用等效阻尼比模型算得的目标位移与基于Rosenblueth模型和Kowalsky模型算得的位移之间存在较大差距。     

Numerical Simulation of Berthing Velocity of the Ship

Based on the field data of berthing velocity for the ship (10000t-50000t), the berthing velocities have been numerically simulated by using Monte Carlo method in this paper. After statistical tests, it shows that the maximum values of the berthing velocity follow a Gumber distribution and the probability curves of failure for the means of maximum values are also obtained. The present results have been compared with the ones determined by specification of harbor engineering both at home and abroad.     

混凝土拉压强度尺寸效应的细观非均质机理

为了从材料细观非均质角度揭示混凝土强度尺寸效应机理,建立了混凝土细观单元等效非均质力学模型,开展了立方体抗拉、抗压强度尺寸效应细观数值模拟研究。研究结果表明：混凝土强度尺寸效应根源于材料细观非均质性,随着模型尺寸的增加,混凝土材料细观单元弹性模量变异系数增大,材料细观非均质性增强,大尺寸模型内部存在更多的低强度单元或缺陷,导致混凝土立方体抗拉、抗压强度降低,极限应变减小,脆性增大;混凝土损伤破坏由少量集中区域,发散扩展形成多条非贯通的裂纹带;数值模拟结果与尺寸效应实验数据相吻合。     

Characteristics of Brittle Failure and Stress Drop Under Triaxial Loading and Unloading

The characteristics of deformation failure and stress brittle drop of granite under loading and unloading conditions are studied respectively based on two unloading stress path cases and conventional triaxial compression experiments. The experiments show that the primary deformation of rock is rebound or tension in the (main) unloading direction, but plastic deformation in the non or sub unloading direction is not significant. And the curves of stress strain after peak strength present obvious brittle. Whilst the primary deformation of rock under loading is axial pressure deformation, and plastic deformation increases with the raise of confining pressure. The fracture is characterized by strong tensile, and all tensile cracks are fully developed. Furthermore, when the rock samples are unloaded in two directions, and even normal to unloading direction, sub unloading annular tensile cracks are produced. The shear fractures is obvious comparatively when confining pressure becomes higher, and it develops following tensile cracks with more micro tension cracks formed in two sides along shear plane. But the fracture is characterized by shear under conventional triaxial compression with little tensile cracks; the coefficients of brittles stress drop of granite is increased with the growth of confining pressure under conventional triaxial compression and reduced under unloading. When the initial confining pressure is the same, the coefficients of brittles stress drop under unloading is less than that under loading. In SchemeⅡ, the coefficients of brittles stress drop reaches negative when initial confining pressure is up to 30 MPa, and the one （R）is RⅢ>RⅠ>RⅡ in three test cases.     

梅花鹿三种深加工制品的营养保健成分研究

分析了测定了鹿茸血酒,鹿心片和鹿鞭精中的蛋白质,脂肪,总糖,维生素及无机微量元素的含量,结果表明,它们是优良的营养保健佳品.     

木工宽带砂光机噪声对人体心率的影响

该文从噪声对人体心率影响的角度 ,分析了木工宽带砂光机 (BSG2 713)的现场噪声及其主要频率的单频噪声对工人生理及心理负荷的影响 .该研究采用的方法是 :以正常工作状况下 ,砂光机的噪声为噪声分析源 ,并提取有代表性的实验噪声 ,在安静及噪声暴露的条件下进行人体心率影响实验 ,最后通过噪声对人体心率的影响情况 ,分析砂光机噪声对人体负荷的影响 .该方法与传统噪声评价方法相比 ,强调了影响劳动安全的人体心理负荷问题 ,从生理学和心理学角度来探讨噪声的影响 .结果表明 :在噪声暴露过程中 ,6 7Hz的噪声对人体心理负荷影响最大 ;而 14 2 2Hz的噪声对人体心理影响波动最大 ,且噪声暴露停止后影响仍持续增加 .     

长输管道定量风险评价方法研究

油气管疲乏的定量风险评价技术是一门新型的管理技术。介绍了定量风险评价技术的内容，以及国外在定量风险评价技术方面所取得的成绩。在我国进行管道的定量风险评价技术具有重要意义，管道管理者可以根据评价结果了解管道的完好状况和提前掌握管道的危险地段情况，以便合理地分配维护资金，交管道的盲目被动维修为预知主动维修，提高管道的运行安全性。