正十二烷喷雾火焰中碳烟的瞬态生成特性

针对压燃式发动机中碳烟演化过程难以被实验准确捕捉的问题,研究了高温高压环境中正十二烷喷雾燃烧焰中碳烟瞬态生成特性及动力学行为,在实验方面,应用消光辐射联合技术以及燃烧成像测速技术,同步获得高温高压环境中单孔喷油器正十二烷喷雾燃烧火焰中的碳烟体积分数、碳烟温度和碳烟速度场的瞬态分布;数值计算方面,基于OpenFOAM环境,发展欧拉喷雾模型和非稳态火焰面进度变量湍流燃烧模型的耦合模型,喷雾燃烧过程的数值计算结果与实验数据有高度的一致性。研究结果表明:相比于参考工况,低喷油压力工况火焰浮起长度更短,碳烟在当量比Φ>2区间驻留时间更长,推动了碳烟的生成,碳烟峰值质量增加了80%;高温环境工况碳烟在当量比Φ>2区间驻留时间没有明显差异,但更短的火焰浮起长度使得燃料在更高的当量比开始燃烧,导致其碳烟峰值质量增加了88%;富氧工况的燃烧温度最高,碳烟粒子运动速度增大,使得碳烟在当量比Φ>2区间驻留时间明显减少,同时火焰内部当量比较小,因而碳烟峰值质量减少了42%。

水陆两栖仿生机器人水下步态生成研究

设计一种拥有弧形腿与桨鳍结合的水陆两栖仿生机器人,提出一种水陆两栖机器人的水下步态映射函数,以期望机器人获得与海龟类似的推进方式。依据海龟的形态结构和运动形态,以Hopf振荡器为基本神经元建立六条腿全耦合式拓扑结构的中枢模式发生器(Central pattern generator,CPG)神经网络。对CPG输出信号以及机器人水下步态映射函数进行分析、优化实现参数的可调性及各步态间转换的平稳性。最后通过仿真与实验验证并生成水下步态生成的转换图,证明了优化后的步态CPG输出信号以及机器人水下步态映射函数的可行性。

随机不确定环境下双足机器人步态扰动平衡控制方法

在随机不确定环境下,双足机器人需要实时地调整步态以保持平衡。同时,控制系统需要具备良好的稳定性,以确保机器人在受到扰动时不会失去平衡或发生损坏,这对控制算法的性能提出了很高的要求。为了提升机器人运动稳定性,提出一种随机不确定环境下双足机器人步态扰动平衡控制方法。通过RCG姿态解算算法获取双足机器人的实时姿态,根据姿态信息生成单足相阶段、双足相阶段以及足部踝关节轨迹,将上述轨迹作为理想轨迹,设计自适应滑膜控制器处理随机不确定环境带来的外部扰动,动态调整控制参数和策略使机器人能够按照理想轨迹稳定行走,以此实现双足机器人步态扰动平衡控制。实验结果表明,在环境扰动下所提方法能够显著提高机器人的稳定性和适应性,显著提高了机器人运动的稳定性。

双足步行机器人在线步态生成与偏航控制策略

针对双足步行机器人的偏航行走需求,提出一种步态生成与偏航行走控制策略,实现步态模式的在线生成与自主偏航行走。其步骤为:首先,基于零力矩点(ZMP)稳定判据,采用线性倒立摆模型和正-逆运动学循环求解算法,建立离线步态生成器;其次,采用预观控制理论,建立用于轨迹跟踪的预观控制器,实现双足步态的在线生成;然后,引入角度系数,运用矢量合成法,根据目标偏航角度,通过回放-纠正方法确定合适的固定系数;最后,采用MATLAB和Adams组成的联合仿真平台,验证方法的有效性。研究结果表明:该方法能利用离线生成的角度,有效减少质心侧向轨迹跟踪误差;通过矢量合成和回放纠正,选取合适的角度系数,实现无偏航步态的在线生成;不需要实时规划参考ZMP轨迹,在保证稳定的前提下,实现15°和30°偏航行走。

一种基于CPG的两足机器人步态生成方法

提出一种基于中枢模式发生器(central pattern generator,CPG)的双足机器人步态生成方法。应用Matsuoka振荡器设计了CPG控制器,其输出控制踝关节角度,膝关节和髋关节角度通过轨迹规划得到。通过将CPG输出与"引导曲线"叠加,实现了机器人的连续稳定行走。该方法避免了CPG繁杂的参数优化过程,是CPG应用的一大进步。MATLAB仿真结果证明了所提方法的可行性。

光源前置消光法测量缸内碳烟瞬态生成过程

开发了一种全新的碳烟测量方法——光源前置消光法(FILE),并进行了台架开发和标定试验。结果表明,FILE测量碳烟仅需一个光学窗口且激光两次穿过碳烟生成区域,因此更适用于结构位置紧凑的发动机缸内测量。采用高速摄像机拍摄了柴油燃烧过程中碳烟情况。表明:碳烟高密度区主要集中在油束下游火焰中心区和缸壁附近低氧区域;环境温度为800 K时,整个燃烧过程中碳烟瞬时质量稳定保持在100μg左右;环境温度1 200 K时,瞬时碳烟质量峰值升高一倍。

基于CPG的仿蟹机器人复杂地形步态生成方法

为了提高仿蟹机器人的复杂环境适应性,提出一种基于生物神经反射机理的自适应复杂地形步态生成方法。首先,采用互抑神经元振荡器构建仿蟹机器人CPG运动控制网络模型;其次,利用具有良好逼近能力的前馈神经网络将CPG输出的节律信号映射为步行足足端轨迹;然后,在CPG模型中引入基于力传感器触发的反射机制,实现了机器人自适应复杂地形步态生成;最后,通过仿蟹机器人复杂地形运动控制的实验研究,验证所提出的基于生物神经反射机理的自适应复杂地形步态生成方法的有效性。

有限元领域中基于孔特征抑制的模型态生成研究

在有限元领域,对复杂模型进行分析需要耗费巨大的计算资源,如何在保证计算精度的前提下有效提高计算效率一直是一项研究重点。为解决这个问题,引入多态模型理论,通过生成合适的模型态来取得结果精度与计算时间的平衡点。因此,模型态的质量直接关系到计算效率的提升程度。孔特征作为有限元分析模型的常见特征,对计算规模有重要影响。文章基于特征抑制的方式探索模型中孔特征的合适处理策略,并结合孔特征的几何属性估计不同策略下生成的模型态的计算精度和计算规模。在此基础上找出几何属性之间存在相互制约的关系,根据经典的加权方法将多目标问题转化成单目标问题,建立模型态选择标准并使用遗传算法选择出最优模型态。

双足机器人动态步行实时步态生成

针对双足机器人动态步行生成关节运动轨迹复杂问题,提出了一种简单直观的实时步态生成方案。建立了平面五杆双足机器人动力学模型,通过模仿人类步行主要运动特征并根据双足机器人动态步行双腿姿态变化的要求,将动态步行复杂任务分解为顺序执行的四个过程,在关节空间相对坐标系下设计了躯干运动模式、摆动腿和支撑腿动作及步行速度调整模式,结合当前步行控制结果反馈实时产生稳定的关节运动轨迹。仿真实验验证了该方法的有效性,简单易实现。

面向理论解的有限元等价模型态生成策略研究

在有限元技术的广泛应用中,存在一个普遍问题,即分析复杂模型十分耗费计算资源。怎样改造模型,使得模型改造前后的分析解的差异在可接受范围内,并有效提高计算效率一直是研究热点。引入的多态模型理论可通过降低初始模型复杂度生成模型态,并用模型态代替初始模型进行计算以提高计算效率。由有限元误差估计理论推导可知,为了使初始模型与其模型态的分析解差异可控,必须首先保证两者的理论解差异可忽略。因此,以初始模型中的几何特征为研究对象,探索合适的特征改造策略,使得依据该策略生成的模型态与初始模型的理论解差异可忽略不计,即两者在理论解的角度上是等价的,为进一步量化估计初始模型与模型态的分析解差异打下工作基础。

当今中国人的完整性生成样态透视

当今中国人的完整性生成样态呈现出优势和劣势并存的态势,既存在经济快速增长所带来的物质财富巨大扩展、政治社会协调发展等有利条件;也存在制约人的完整性生成的不利因素:人的劳动仍存在一定程度的异化,人生成的时间空间尚待平衡,人的个性生成仍受一定的依附观念制约,人的精神世界容易被膨胀的物的需要侵蚀。当务之急是创造和培育人的完整性生成的因素、条件和前提。

自动生成舰船浮态调整措施的实时运算方法

本文根据舰船使用的实际需要，分析了利用液舱调整浮态的基本原则，研究出一套适用于自动生成浮态调整方案的运算逻辑和限值判断计算方法，解决了实时计算的速度和精度问题，并能得到合理的结果。该方法已应用于实船。

浅谈如何动态生成高中数学高效课堂

本文就如何构成动态生成高中数学高效课,从几个方面加以论述,值得高中数学教师借鉴.

基于双生成函数的步行机器人最优步态生成

将最优控制理论中的双生成函数方法应用到双足步行机器人的在线最优步态生成中.针对线性化的机器人模型,分别以关节角度和力矩为状态和输入变量,考虑能量消耗,构造线性二次型最优控制问题.基于一对生成函数推导得到该问题的解,可以参数化为线下计算系数和边界条件,相对应的求解过程由线下数值积分部分和线上代数运算部分组成.通过设置多步仿真实例进行计算.结果表明,利用该方法可以显著地提高机器人步态的在线生成效率.设计比例微分控制器,当机器人以合理的步长和适当的时间段行走时,由线性化引起的建模误差可以被控制在较小范围之内,非线性模型的轨迹可以很好地跟踪线性化模型的轨迹.

基于腰关节力矩补偿的仿人机器人快速步行模式生成

为了有效地提高仿人机器人动步行能力,利用基于预观控制的ZMP步态生成模式的优点并引入脚尖脚后跟与地面间的旋转关节,生成了机器人的质心和踝关节轨迹.同时,为了得到更快的步行速度,提出了侧向质心摆动幅度递减和腰关节偏摆力矩补偿的方法.最后在虚拟物理环境下,利用动力学仿真软件实现了虚拟3-D仿人机器人快速动步行.仿真结果证明了所采用方法的有效性.

Slope displacement prediction based on multisource domain transfer learning for insufficient sample data

Accurate displacement prediction is critical for the early warning of landslides.The complexity of the coupling relationship between multiple influencing factors and displacement makes the accurate prediction of displacement difficult.Moreover,in engineering practice,insufficient monitoring data limit the performance of prediction models.To alleviate this problem,a displacement prediction method based on multisource domain transfer learning,which helps accurately predict data in the target domain through the knowledge of one or more source domains,is proposed.First,an optimized variational mode decomposition model based on the minimum sample entropy is used to decompose the cumulative displacement into the trend,periodic,and stochastic components.The trend component is predicted by an autoregressive model,and the periodic component is predicted by the long short-term memory.For the stochastic component,because it is affected by uncertainties,it is predicted by a combination of a Wasserstein generative adversarial network and multisource domain transfer learning for improved prediction accuracy.Considering a real mine slope as a case study,the proposed prediction method was validated.Therefore,this study provides new insights that can be applied to scenarios lacking sample data.

Ultimate pit optimization with ecological cost for open pit metal mines

The ecological costs of open pit metal mining are quantified, which include lost value of direct eco-services, lost value of indirect eco-services, prevention and restoration costs, and cost of carbon emission from energy consumption. These ecological costs are incorporated in an iterative ultimate pit optimization algorithm. A case study is presented to demonstrate the influence of ecological costs on pit design outcome. The results show that it is possible to internalize ecological costs in mine designs. The pit optimization outcome shifts considerably to the conservative side and the profitability decreases substantially when ecological costs are accounted for.

基于CPG的仿海蟹机器人浮游步态生成方法

结合仿生游动机理,针对游泳桨推进仿海蟹机器人提出一种基于中枢模式发生器浮游步态生成方法.采用可独立控制频率、幅值、相位延迟和时间非对称系数的一类非线性振荡器作为节律信号发生器,通过最近相邻耦合的方式构建了仿生游动的链式中枢模式发生器（CPG）运动控制模型,并分析了振荡单元平衡点的性态,证明了振荡器极限环存在的唯一性和稳定性;在此基础上,引入三个顶层控制信号作为CPG网络的激励,分别用来控制机器人的游动速度、转艏速率和浮潜速率,实现了仿海蟹机器人的三维游动控制.实验结果显示样机具有一定稳定性和机动性,机器人的直线游动速度和转艏速度随着游速控制系数和转艏速率控制系数的增加而增大,最大直线游动速度可达0.41 BL/s,最大原地转艏速率可达1.7 rad/s.仿真及实验结果验证了此中枢模式发生器模型的可行性与所提控制方法的有效性.

Discussion on Action and Potential of Fenlong Megascience in the Symbiosis between Human and Nature

The fourth new farming model Fenlong is identified as megascience for the first time. Fenlong can be directly applied to farming of farmland, remoulding of mortar black soil and saline alkali land and development of degraded grassland. Deep loosening can create huge soil reservoirs, reduce fertilization, promote indi- rectly the improvement of river water fisheries and water sources and the upgrading of shaping and hydropower industry, thus making a new round of mobilization and pooling of natural resources. As a result, the nature is able to produce good food needed by human, the spatial dimension of the land is increased, the natural pre- cipitation storage is increased, the flood and drought disasters are reduced, the eco-environment is improved, and the economic benefits are increased. Fenlong is not restricted to global application by ecological region and crop variety and is not subject to the time-space constraints for a hundred thousand years. On the basis of utilizing the heaven and earth resources, it brings about a huge effect of mega- science. Compare with traditional farming, the depth under the mode of Fenlong is increased by 2-3 times, the contents of nutrient, water, oxygen and microorganism in the soil are increased by 10%-200%, the content of pale salt is increased by 20%-40%, the temperature is increased by 2-4 ~C, and the photosynthetic efficiency of crops is improved by 10%. Under the cultivation mode of Fenlong, the yield of crop applied with no fertilizers is increased by more than 10%, crop yield is still in- creased by more than 5% when the application amount of chemical fertilizer is re- duced by 10%-20%. Under the farming mode of Fenlong combined with no in- crease in fertilization, the crop yield, crop quality, farming efficiency, natural precipi- tation storage and air humidity are increased by 10%-50%, 5%, 15%, 100% and 5%, respectively, and the emissions of methane and other gases are reduced by more than 5%. Even in mortar black soil, saline alkali land and degraded grassland, the yield is still increased by 15%-50%. These improvement effects can last for many years, helping achieve the real harmonious coexistence between human and nature.

Dynamic Changes of Land Ecological Carrying Capacity Based on the Ecological Footprint——By the Case Study of Chengdu City

Chengdu City is in the period of rapid urbanization and industrialization, and the disturbance derived from human activities on environment is increasing remarkablely in recent 20 years. The pressure on environment, economy and population is also increasing and land use in Chengdu has changed enormously. As struc- ture and function of land ecological system change obviously, sustainable development of land productivity has been an important goal and strategic task from now on, and it is necessary to systematically research land ecological carrying capacity based on ecological footprint. The ecological footprint of Chengdu City in the past ten years was calculated and analyzed from the spatial and temporal aspects according to statistical data from 1998 to 2008, as per ecological footprint method, ecological carrying capacity and the GIS spatial analysis method, and regression analysis method. The ecological footprint and ecological carrying capacity values from 2009 to 2019 in Chengdu City were predicted through calculation results in the past ten years. The results show that the ecological footprint and ecological deficit of land use from 1998 to 2008 increased in Chengdu City. The ecological deficit of land use within the city center was in high levels in the past ten years, and the ecological footprint kept raising, especially in areas, such as Shuangliu, Chongzhou, Qingyang among 9 city areas, 4 counties and 6 districts in Chengdu City. There is fanlike distribution of ecological deficit of land use. Analysis shows that the social and natural ecological system is uneven distribution, which is not in sustainable de- velopment situation. The results of the study show that the economic, social and natural ecological system in Chengdu City is not sustainable, and the ecological foot- print is uneven distribution. The analysis of the dynamic change of land ecological carrying capacity in Chengdu City is very important for city government in the pro- cess of the vigorous development in new Tianfu Xinqu, and redevelopment in the northern part of this city.