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Search Results: 1 - 10 of 88922 matches for " 石永飞 "
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岩质边坡滚石飞落模型与防治技术
Free-fly rolling model of stone on rock slope and control techniques

,??,,孟家琪
- , 2018,
Abstract: 针对公路岩质边坡的滚石灾害问题,建立岩石跳跃滚落的理论分析模型,推导了岩石运动的轨迹方程、滚石第1次落点后的水平速度和竖向速度以及第2次落点的水平距离,计算了滚石掉入构筑物表面的水平距离和对砂垫层的撞击能,并计算了滚石撞入砂垫层的入土深度,分析了撞击能与入土深度的关系,同时推导出了滚石落入砂垫层的冲击压力、最大法向压应力、撞击能以及压入量,并通过2个算例对提出的模型进行验证,根据计算结果选取了合理的防护方式对滚石灾害进行防护。研究结果表明:算例1滚石对砂垫层的压入量为1.28 m,设计构筑物上的砂垫层厚度为2 m,同时考虑到构筑物的安全储备,滚石撞击坡面后的水平运动距离小于撞击点到公路路缘的水平距离,滚石飞落至地面的撞击能为167 kJ,采用型号为AXI-015(防护等级为200 kJ)的被动防护网可有效防护构筑物,避免安全事故的发生;算例2滚石落入砂垫层的压入量为0.87 m,撞击能为124 kJ,设计洞口顶回填1.5 m厚的砂垫层,采用防护等级为150 kJ的被动防护网可有效防护边坡滚石灾害。采用提出的模型计算并进行防护的效果非常明显,证明了所建模型的可实施性,为以后类似工程提供了有益指导。
Aiming the problem of rolling stone disasters of highway rock slopes, a theoretical analysis model of rock jumping and rolling was established. By deducing the trajectory equation of rock movement, the horizontal velocity and vertical velocity of the first drop point of rolling stone and the horizontal distance of the second drop point were derived. In addition, the horizontal distance of rolling stone falling into the structure surface and the impact energy on sand cushion were calculated, the depth of rock rolling into sand cushion was calculated, and the relationship between impact energy and depth was analyzed. At the same time, the impact pressure, the maximum normal compressive stress, the impact energy and the amount of indentation of rolling stone falling into sand cushion were derived. The proposed model was verified by two examples. According to the calculation results, a reasonable protection method was selected for the protection of rolling stone hazards. The results show that in the first example, the amount of indentation of rolling stone falling to sand cushion is 1.28 m, and the thickness of sand cushion on the designed structure is 2 m. Considering the safety reserve of structure, the distance of horizontal movement of rolling stone after hitting the slope is less than the horizontal distance from the impact point to road edge, and the impact energy of rolling stone flying down to the ground is 167 kJ. The passive protective net of AXI-015 (protection grade is 200 kJ) can effectively protect the structure and avoid accident. In the second example, the amount of indentation of rolling stone falling into sand cushion is 0.87 m, the impact energy is 124 kJ, and the thickness of sand cushion with 1.5 m is backfilled to the top of the designed hole. The passive protective net of AXI-015 (protection grade is 150 kJ) can effectively protect slope rolling rock hazards. The effect is obvious of which using proposed method for calculation and protection. At the same time, it is proved that the model can be implemented, which can provide
线性分布荷载作用下梯度功能压电悬臂梁的解
,,陈盈
力学学报 , 2004, DOI: 10.6052/0459-1879-2004-3-2002-039
Abstract: 采用逆解法求解了上表面受线性分布荷载作用的压电悬臂梁执行器,其中体积力$F_z$呈非线性分布.首先确定了应力函数和电位移函数的多项式表达式,进而研究了该问题的通解,以及体积力的不同分布对解答的影响.常体积力和无体力情况下的解可以由上述解直接得到.本文为研究其它类型的压电梯度微观结构提供了一种可行的方法.
双洞效应的黄土公路隧道变形影响离心模型试验
Centrifuge Model Test on Deformation Influence of Loess Road Tunnel Basedon Double-hole Effect

,,来弘鹏,
- , 2016,
Abstract: 摘要 目前,有些黄土公路隧道受到地形限制只能采取小净距隧道形式,为了更好地解决彼此开挖相互受影响带来的安全隐患问题,笔者开展了6组基于先加载后开洞思路的离心模型试验,研究了不同净距和间距的组合下双洞效应黄土公路隧道地表及地层的变形规律。试验结果表明:间距保持1D时,随着净距的增大,双洞间的相互影响程度明显减弱,先行洞开挖对后行洞的次生扰动逐级递减;地表沉降轮廓由单核心盆地演变为多核心盆地,地层变形曲线从V形发展为W形;压力拱效应明显且成拱高度随两隧体净距的增加而升高。间距变为2D时,无论净距如何取值,地表和地层沉降的最大值都会在右侧隧道中心线附近出现,右侧隧道上覆土体变得更为敏感。净距2D间距2D时,地表和地层沉降均在右侧先行隧道拱顶上方出现6组工况下的最大沉降值,评定为最不利工况;间距1D净距取1.5D和2D时,两隧体间均可形成自稳的宽底承载土柱体。因此,小净距黄土公路隧道合理净距取值范围为1.5D~2D,相应的掌子面间距宜控制在1D内。
Piezoelectric Cantilever Actuator Subjected To A Linearly Distributed Loading
线性分布荷载作用下梯度功能压电悬臂梁的解

Yang Yongbo Shi Zhifei Chen Ying,
,,陈盈

力学学报 , 2004,
Abstract: The inverse method is traditionally used to solve elastic problems. In the present paper this method is applied for a piezoelectric cantilever actuator subjected to a linear distributed loading on the upper surface. Nonlinear body force Fz is also considered. The stress function and induction function in the form of polynomials are obtained. The general solutions as well as the influence of the distribution profile of body force on this solution are discovered. From this conclusion the solutions of the cantilever actuator with constant body force and without body force can be easily found. This work provides a feasible method to study other kinds of functionally gradient piezoelectric microstructures.
数字控制400Hz三相四线高功率因数PWM整流器研究
健将,,王文杰,张际海,张建国
电工技术学报 , 2012,
Abstract: 根据航空电源系统中AC-DC静止变流器的应用需要,设计了一套数字控制400Hz三相四线高功率因数PWM整流器系统。传统的直接电流控制方法由于被控量是交流信号,因而存在着相位静差问题,本文采用基于dq同步旋转坐标变换的空间矢量控制方法,实现了输入电流与输入电压间的相位无静差控制,实现了高功率因数目的;针对三相四线结构输出串联电容均压问题,本文提出了输出串联电容均压环与中线电流环串联的双闭环控制方法,实现了输出串联电容均压控制。最后在理论分析与仿真的基础上搭建了3kW原理样机,仿真和实验结果均验证了该系统控制方法的正确性与可行性。
长行程直线电机的迭代学习控制
阳春,周云,李鸿,李介明,
中国电机工程学报 , 2007,
Abstract: 光刻机工件台在扫描曝光过程中要求纳米级的定位精度,采用长行程直线电机粗动加洛仑兹电机高精密微动补偿的6自由度复合运动系统能满足要求。为减小微动电机的运动范围和加速度,必须提高直线电机的轨迹跟踪精度。提出了一种开闭环D型迭代学习控制律改善永磁直线同步电动机(PMLSM)的轨迹跟踪性能。控制器由三部分组成:PID控制器用来提高系统对扰动和参数变化的鲁棒性;前馈补偿器可提高系统的实时跟踪性能;迭代学习控制器则通过执行重复任务来不断向理想的控制信号逼近。实验结果表明,这种控制方法可以有效提高系统的轨迹跟踪精度。
纤维增强塑料筋混凝土梁抗弯设计数值分析
李炳宏,江世,,钱华,胡显奇
长安大学学报(自然科学版) , 2011,
Abstract: 为预测纤维增强塑料筋(FRP筋)混凝土梁在受弯工作过程中弯矩和挠度的发展情况,从而为FRP筋混凝土梁的抗弯设计提供依据,采用对构件正截面进行分层的方法,根据极限强度理论、应变协调条件和内力平衡条件,对构件的弯矩-曲率关系和荷载-挠度关系进行了数值计算,并编写计算代码,设计图形用户界面(GUI)。理论计算结果与试验结果的比较说明,采用极限强度理论可以较好地预测FRP筋混凝土梁的极限弯矩,对于FRP筋混凝土梁短期挠度的计算,ACI模型的计算结果过小,Faza&GangaRao模型可以较好地预测构件在正常使用极限状态下的短期挠度,所采用的数值计算方法则可以较好地预测构件在短期荷载作用下的极限挠度。各种挠度计算方法之间的对比表明,所采用的数值计算方法更加适合于FRP筋混凝土梁短期挠度的求解。
盐胁迫对大豆种子萌发及矿质元素变化的影响
,周妍,徐明,徐靖宇,金晓,连旋**
生态学杂志 , 2015,
Abstract: ?以大豆为试验材料,测定了中性盐和碱性盐胁迫下大豆种子的萌发、生长参数及各种矿质元素的含量,试图揭示盐胁迫下大豆种子萌发与矿质元素的响应过程及其相互关系。结果表明:大豆种子的萌发率、萌发势、萌发指数及生物量等在高浓度盐胁迫下均呈降低趋势,高浓度碱性盐胁迫比中性盐胁迫下降的趋势更为显著;盐胁迫下,大豆种子萌发过程中矿质元素含量与萌发参数存在显著相关关系。同时,盐胁迫下各种矿质元素在大豆子叶中呈逐渐降低、根中逐渐升高的趋势,造成了大豆体内矿质离子不平衡;尤其是高浓度碱性盐胁迫下,大豆根中矿质元素积累量更大,离子失衡更为显著。研究表明,盐胁迫尤其是高浓度碱性盐胁迫造成了大豆种子中矿质离子大幅度的失衡,对大豆种子的萌发和生长造成严重的伤害。?
地震勘探安全距离的标定方法研究
Calibration Method for Safety Distance during Seismic Exploration

双虎,丁向晖,,杨阳,单启铜
- , 2017, DOI: 10.3969/j.issn.1000-0844.2017.01.0186
Abstract: 随着地震勘探的不断推进及人类活动范围的扩大,地震采集工作法避免会涉及到越来越多的复杂地表条件和采集环境,如城区、油区等障碍物繁多的地区及环境高敏感区域。大量障碍物既影响地震采集质量和资料品质,也给施工安全造成威胁。在过渡带地震勘探中,由于激发方式多样化,安全距离的确定较为复杂,稍有不慎,很容易引起安全事故和造成资料缺失。本文基于振动效应的原理对混源激发中的安全距离进行理论探讨和实际测试,其结果对于复杂地区的地震勘探施工有着一定的指导意义。
With the continuous advancement of seismic exploration and an expansion in the range of human activities,areas of exploration and associated surfaces have become increasingly complex to negotiate when acquiring seismic data.In addition,areas of exploration have now been expanded to urban areas,oil areas,pipelines,and other places where there are a variety of obstacles,which results in the need for complex seismic operational methods,and involves greater operational difficulty and lower work efficiency.During seismic data acquisition of complex transition zone (TZ),the obstacles are usually numerous,and the work area often contains intricate pipelines,wells,power grids,buildings,and areas under nature protection.In addition,mixed excitation methods are required,such as vibroseis,explosives,and different kinds of air guns.With the continuous increase in awareness of seismic operational safety and environmental protection,the valid acquisition area of seismic projects has become increasingly narrow,and the range of source point deployment has increasingly reduced.These factors are leading to the acquisition of poor quality seismic data,and even data gaps in some areas.There is an urgent need to determine effective acquisition space to reasonably lay out source points.Optimization of geometry,and excitation and receiving parameters improve seismic data quality,and although the use of data interpolation can compensate for missing data during later processing it is associated with "false" suspects.During actual operations,safe distance values are usually provided by clients or determined using instrument tests.However,safety distances are generally too large,and thus the effective acquisition space is greatly compressed.Based on above two points,this paper uses Sadov's vibration formula,known in engineering blasting,for seismic exploration,and combines flexibility of testing instruments and scientifically calibrated safety distances,thereby improving the capacity of the source layout,which further expands the seismic acquisition space,improves the quality of seismic data,ensures the safety of operations,and enhances the operation schedule.The research provided in this paper is thus of considerable use for seismic exploration in complex areas.
田间接种固氮类芽孢杆菌对小麦的增产效应
Effect of nitrogen-fixing Paenibacillus spp.on wheat yield

皓文,,李朋,王志敏,陈三凤
- , 2016,
Abstract: 为了解固氮类芽孢杆菌对小麦的增产效果,对实验室分离保存的4株固氮类芽孢杆菌菌株1-18、1-33、1-43 及1-49,在固氮酶活性、吲哚乙酸(IAA)分泌量及接种小麦后的增产效果进行了比较。结果表明,这4株固氮类芽孢杆菌接种小麦后,比不接种固氮菌剂的对照增产5.1%~26.9%,其中菌株1-18的增产效率最高(增产26.9%),其次是菌株1-49(增产18.7%)。相应地,这2株菌株的固氮酶活性也比其他2株菌株高,菌株1-18固氮酶活性为1 043.6 nmol/(mg·h),菌株1-49为969.5 nmol/(mg·h),但分泌的IAA量低于其他2个菌株,菌株1-18 分泌IAA量为24.95 μg/mL,菌株1-49分泌IAA量为26.34 μg/mL。结果说明用于本研究的固氮芽孢杆菌在固氮酶活性、IAA分泌量及对小麦的增产效果方面存在差异。
Four nitrogen-fixing Paenibacillus strains 1-18, 1-33, 1-43 and 1-49 are used to inoculate wheat, and the wheat yields are analyzed to determine the effect of these strains on wheat yields.The results showed that wheat yields were increased by 26.9%, 9.7%, 5.1% and 18.7%, respectively.Furthermore, the nitrogenase activities and IAA amounts produced by these 4 strains were analyzed.Of these 4 strains, strain 1-18 exhibited the highest nitrogenase activity (1 043.6 nmol/(mg·h)) and the activity (969.5 nmol/(mg·h)) of strain 1-49 is higher than the rest 2 strains 1-33 ((565.9±3.0) nmol/(mg·h)) and 1-43 ((904.5±4.3) nmol/(mg·h)).However, the IAA amounts produced by strains 1-18 ((24.95±1.2) μg/mL) and 1-49 ((26.34±4.2) μg/mL) are lower than those produced by strains 1-33 ((27.73±1.8) μg/mL) and 1-43 ((49.91±3.6) μg/mL).Our study provided fundamental information for strain improvement of nitrogen-fixing strain for microbial fertilizer.
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