矿用振动筛是煤炭洗选行业的关键设备之一,主要应用于对原煤进行分级、脱泥、脱水等。由于矿用振动筛长期在恶劣的环境下高负荷运转,使得筛机的主要部件频繁发生故障,给洗选煤行业造成了较大的经济损失,故障严重时甚至能够造成人员的伤亡。因此研究如何对矿用振动筛进行状态监测以及故障诊断与预警,具有重要的学术价值与实用意义。文章首先应用ANSYS软件对矿用振动筛整体以及激振器大梁进行了模态分析,通过研究各阶振型,找出了侧板与大梁在各阶固有频率下形变较大的位置,并以此为依据设计了对侧板与大梁损伤的监测方案。为了探究筛箱异常振动故障机理,建立了基于支撑弹簧刚度的振动筛动力学模型,并通过ADAMS软件对振动筛的运动过程进行了仿真分析,得出支撑弹簧的振动位移与相位不一致会引起筛箱不同形式的偏摆。应用LabVIEW软件编写了获取支撑弹簧振动位移与相位的算法程序,设计了筛箱异常振动故障监测方案。在激振器轴承故障的研究中,首先对滚动轴承的故障机理进行了分析,采用基于小波降噪的EEMD包络解调算法获取激振器轴承的故障信息,并通过仿真验证了算法的有效性,进而设计了激振器轴承的故障监测方案。基于上述理论研究,本文将LabVIEW软件与MATLAB软件相结合,开发了矿用振动筛状态监测与故障诊断软件系统,用以监测矿用振动筛的运行状态,并对大梁与侧板损伤、筛箱异常振动以及激振器轴承故障进行数据采集与故障诊断。最后在现场对系统进行应用测试,验证了系统的有效性与实用价值。

随着科技的进步,人机交互、辅助医疗和机器人等技术在日常服务领域的应用日益增多,为人们的生活带来了诸多便利。本课题基于辅助老年人徒步行走、降低自身体能消耗的现实意义,以结构简洁灵活性、系统稳定性和穿戴舒适性为设计目标,开展了下肢外骨骼机器人的设计研究。主要研究内容如下:基于人体下肢结构特性、运动机理和行走步态,对外骨骼机械结构进行仿生设计,确定了总体尺寸,设计出整体构型方案,并完成驱动关节的配置及驱动方式的选取;利用Solidworks软件建立了外骨骼虚拟样机,并利用Workbench软件对受力最大的单腿支撑相和处于过渡时期的双腿支撑相进行了静力学分析,仿真结果表明,外骨骼所受的最大应力低于材料的许用应力、最大形变量符合设计要求。基于D-H参数坐标法和微分变换法,对外骨骼进行正、逆运动学分析,得出主动关节的运动特性;运用拉格朗日法对外骨骼进行动力学分析,建立了动力学方程;针对外骨骼的适用对象,拟合出适合穿戴者步态的数据曲线,创建了基于ADAMS模型,并进行运动仿真,得到髋关节、膝关节和踝关节轨迹曲线、行走位移及步长曲线;通过分析行走步态特征,验证了结构设计和步态参数的合理性。基于ZMP稳定性判据的步态规划方法,首先利用多项式插值法对外骨骼踝关节、髋关节运动曲线实现参数化,然后利用遗传算法对步态参数后续优化,最后求解出髋关节、踝关节的运动轨迹;借助Matlab软件建立了运动学模型,并通过分析模型角位移和角速度的变化轨迹,验证了步态规划的可行性与正确性,得出所设计的外骨骼具有穿戴舒适和实用较高的特点。

The main cause of underground disasters in coal mines is the stress concentration and high-intensity unloading of surrounding rock caused by man-made mining and the extraction of coal resources. Especially when the surrounding rock is affected by confined water, it is easy to lose stability and damage, which leads to the occurrence of disasters. Accordingly, the experimental study on the mechanical properties and energy evolution law of sandstone under the coupling of seepage and mining stress was carried out by means of Rock Top multi-field coupling tester. The test results show that: (1) The total stress-strain curve of sandstone can be divided into five stages. After the sandstone begins to unload, it changes from axial deformation to circumferential deformation. (2) The peak stress of sandstone increases with the increase of unloading level. With the increase of osmotic pressure difference, the peak stress of sandstone is not obvious due to the superposition of surrounding rock and water pressure. (3) The higher the unloading level of sandstone is, the larger the axial strain value at the peak stress is, and the axial deformation of sandstone is more obvious under high unloading level. The evolution law of dilatancy angle curve of sandstone roughly follows the law of ' increase—ecrease—increase—decrease ', and the expansion behavior of sandstone is more significant under low unloading level. (4) With the increase of initial unloading level, the elastic strain energy density of sandstone increases as a whole. The energy distribution coefficient of elastic strain energy density increases first and then decreases with the increase of axial strain of rock sample. (5) The instantaneous energy distribution coefficient of elastic strain energy of sandstone presents the change rule of 'increase—decrease—increase 'with the increase of axial strain of rock sample. The energy storage capacity of sandstone elastic strain energy reaches its peak after entering the elastic deformation stage, and its energy release capacity reaches its peak before entering the residual stress stage. © 2025 Biodiversity Research Center Academia Sinica. All rights reserved.

The effect of oxidation degree of graphene oxides (GO) on their removal from wastewater via froth flotation was studied in this work. Four types of GO samples with different oxidation degrees were synthesized and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), atomic force spectroscopy (AFM) et al. The effects of cetyl trimethyl ammonium bromide (CTAB) concentration, pH, stirring time on the removal of GO by froth flotation had been discussed. It was found that the addition of CTAB could improve surface hydrophobicity of GO, endowing GO to be easily separated by froth flotation. The removal was dependent on CTAB dosage, pH and stirring time. Moreover, the removal first increased and then decreased with the increasing oxidation degree of GO, and less kinetic energy input was needed to overcome the energy barrier between GO flocs with the increase of oxidation degree. The removal mechanism was proven to be electrostatic attraction, and the different contents of oxgenous-containing functional groups in GOs with various oxidation degrees played a vital role in their removal via froth flotation. (C) 2020 Elsevier Ltd. All rights reserved.

外骨骼机器人是一种穿戴在人体上,辅助人体运动的机械装置。随着机器人技术的发展,外骨骼的结构越来越复杂,自由度越来越多,这使得动力学研究的难度急剧增大,因此急需一种高效的动力学计算方法。根据上述研究背景,本文针对多自由度下肢外骨骼机器人的建模和高效动力学计算展开了一系列探索性研究,主要包括下肢外骨骼机械系统的设计、下肢外骨骼运动学与动力学分析、浮动基座模型逆动力学算法的研究、下肢外骨骼运动学与动力学仿真分析等。对下肢外骨骼进行总体结构设计。对人体下肢生理结构和关节运动机理进行研究,得到人体下肢的尺寸数据和关节运动范围,在此基础上确定了下肢外骨骼的构件尺寸、关节自由度数和驱动方式,借助SolidWorks完成了下肢外骨骼的三维实体建模,使用有限元方法对关键结构进行了强度校核。对下肢外骨骼进行运动学分析与动力学建模。使用D-H法建立单侧下肢外骨骼的运动学模型,通过运动学求解,确定了足部装置的位姿与关节转角之间的关系,使用MATLAB对足部装置的运动轨迹进行计算,采用蒙特卡洛法对足部装置的工作空间进行分析,验证了运动学分析的正确性。采用牛顿-欧拉方程法建立了下肢外骨骼的浮动基座动力学模型,构造了下肢外骨骼的运动树,使用空间向量计算出运动树中的模型数据。对下肢外骨骼进行动力学计算。由于本文建立的是下肢外骨骼浮动基座动力学模型,导致固定基座模型逆动力学算法失效,因此将其改进为浮动基座模型逆动力学算法,并将运动树代入算法进行下肢外骨骼的动力学计算。通过浮动基座模型逆动力学算法,得到了下肢外骨骼在步态运动过程中各关节驱动力矩的大小。结合人体步态规律对计算结果进行分析,并将计算结果和CGA步态数据库中的关节力矩进行对比,验证了浮动基座模型逆动力学算法的正确性;将拉格朗日法、牛顿-欧拉法和浮动基座模型逆动力学算法的计算效率进行对比,验证了浮动基座模型逆动力学算法的高效性。最后,建立ADAMS下肢外骨骼虚拟样机模型,使用ADAMS对下肢外骨骼进行运动学与动力学仿真,分析外骨骼在运动过程中的角度、速度、力矩变化曲线,验证所建立的仿真模型的正确性和浮动基座模型逆动力学算法的正确性。

Due to the challenges of separation and high costs, coal slime is often directly burned without further separation processing, leading to environmental pollution. Therefore, a feed -regulated water -only cyclone has been proposed to improve the coal slime separation efficiency by controlling the suspended bed. This method optimizes particle characteristics by incorporating a pre-desliming hydrocyclone, the characteristics of particles were optimized to regulate the hindered settling in suspension layer. Response surface experiments were conducted to investigate the impact of structural parameters on separation efficiency, Additionally, under optimal parameter conditions, particle size and density were characterized, and a simulation analysis was conducted using CFD-EDEM. The results showed that the maximum separation efficiency achieved in the experiment was 35.31%. Particle characterization analysis also revealed that, after feed regulation, the proportion of particles with a size of 0.045 mm within high density exceeded 75%. Industrial application experiments demonstrated the feasibility of obtaining a high -quality coal product with over screen yield of 9.29% and an ash content of 9.47%. This transformation of coal slurry into a valuable resource has generated significant economic benefits for enterprises and will address the environmental pollution issue caused by direct combustion and improper disposal.

Rock mass disasters are caused by instability driven by energy within the rock mass. The excavation and unloading disturbance can lead to fractures and instability in the rock mass structure, which is a major cause of dynamic disasters such as water inrush in stopes. To understand the influence of excavation unloading on rock mass structure fractures and to clarify the degradation law of surrounding rock and the mechanism of dynamic disasters like water inrush, this study focuses on the characteristics of rock damage and the evolution of energy under stress-seepage coupling factors. Using the Rock Top multi-field coupling tester, the study investigates the rock damage characteristics and energy evolution under three stress paths: conventional triaxial compression (group C), conventional unloading confining pressure with different initial damage degrees (group W), and cyclic loading and unloading confining pressure (group X) under the influence of stress-seepage coupling. Based on the evolution characteristics of rock elastic strain energy, the stress-strain curve of rock under conventional triaxial compression (group C) is divided into five stages, and the characteristics of U1, U3, Ue, Ud and permeability change in each stage are explained in detail (Ue is the elastic strain energy, Ud is the dissipated energy, U1 is the strain energy of the rock transformed by the positive work done by the axial stress on the rock, and U3 is the strain energy released by the negative work). During the conventional confining pressure unloading process, the evolution law of U1 and U3 is similar to that of group C rock, but the negative growth of U3 is more significant. The rock input energy gradually shifts from Ue to Ud, and the initial damage degree has no significant influence on the law. During the confining pressure unloading process, the permeability shows a fluctuating upward trend, and the confining pressure is negatively correlated with the permeability. In the process of cyclic loading and unloading confining pressure, the energy evolution law is similar to that of group W rock, with energy accumulation differing only due to time effects. On the whole, regardless of the stress path, the pre-peak rock is dominated by Ue, representing energy storage, while post-peak rock is dominated by energy release and dissipation. Axial stress loading is the main influencing factor for rapid accumulation of Ue, while the change in confining pressure is not enough to cause a large change in Ue. Axial load is the primary factor influencing engineering disasters. Furthermore, there is a significant negative correlation between rock damage variable and confining pressure. The larger the confining pressure is, the smaller the Ue release ratio of rock is, and the smaller the rock damage is. Confining pressure restraint effectively enhances the energy storage capacity of rock and inhibits the dissipation and release of rock energy. © 2024 Biodiversity Research Center Academia Sinica. All rights reserved.

In order to explore the law of deterioration and damage of roadway surrounding rocks and to clarify the water inrush mechanism of roadway spalling，laboratory tests on deterioration and seepage characteristics of sandstone under three stress paths of conventional triaxial(group C), conventional discharge of confining pressure(group W) under different initial damage degrees，and cyclic loading and unloading confining pressure discharge(group X) were carried out based on Rock Top multi-field coupling tester. The results show that：(1) At the beginning of cyclic loading and unloading confining pressure of group X rocks，the axial deformation of rocks is slower than the lateral and volume deformation，but cyclic loading and unloading confining pressure can lead to "strain accumulation" of rock，which makes the stress drop point of rock in group X appears "hysteresis effect" compared with group W. (2) The initial damage significantly affects the rock strength and the sensitivity to the confining pressure. The initial damage degree of rocks in group X and group W is negatively correlated with the unified confining pressure drop parameter(η )，and positively correlated with the incremental ratio of the strain and the confining pressure(λi ). The parameter η of group X is smaller than that of the group W，while λi is greater than that of the group W. (3) Obvious brittle failure of rocks occurs in groups X，group W and group C，and the main failure mode is shear failure. When the initial damage degree is low，the rock failure degree of group X is large，accompanied by local macroscopic cracks. (4) The rock permeability is affected by the factors such as rock pores，framework structure and crack development. The rock seepage-strain relationship curves of groups X and group W can be divided into three stages. The first and third stages are consistent. In the second stage，the rock permeability of group X decreases first and then increases，while the rock permeability of group W increases as a whole. (5) The permeability fluctuation of group X tends to be obvious with the increase of the circulation grade. The higher the initial damage degree is，the more easily this phenomenon occurs. The number of cycles has little effect on this law，but the increase of the number of cycles has an inhibition effect on rock seepage，and the inhibition effect is more significant than that caused by the decrease of confining pressure. © 2023 Academia Sinica. All rights reserved.

In order to explore the mining failure law of deep coal seam floor and clarify the mechanical behavior and energy change in the floor strata during mining, the mechanical properties and energy evolution law of sandstone under cyclic loading with different confining pressures (20, 30, 40 MPa) were studied using the Rock Top multi-field coupling tester. The results are as follows: (1) the hysteresis phenomenon of a rock stress-strain curve under cyclic loading is evident. Moreover, the hysteresis loop migrates to the direction of strain increase, and the fatigue damage caused by cyclic loading has a certain weakening effect on the peak strength of rock; (2) both the number of cycles and the axial strain show a nonlinear change characteristic that satisfies the quadratic function relationship. Among them, the stress level of the rock is the main factor affecting the fitting effect; (3) under the same confining pressure, with an increase in cycle level, the macroscopic deformation of the rock increases, the accumulation of fatigue damage in the sample increases, and the irreversible deformation of the rock increases, which leads to an increase in energy input and dissipation; (4) in terms of elastic energy and dissipation energy, elastic energy plays a dominant role. In the initial cycle, the rock is destroyed, and the rock energy loss is great. After the second cycle, the input energy is mainly stored in the rock in the form of elastic energy, and only a small part of the input energy is released in the form of dissipation energy; (5) the confining pressure can improve the efficiency of rock absorption and energy storage, enhance the energy storage limit of rock, and limit the dissipation and release of partial energy of rock. The greater the confining pressure, the more evident the limiting effect, and the more significant the dominant position of elastic energy; and (6) the change in the energy dissipation ratio can be divided into three stages: rapid decline stage, stable development stage and rapid rise stage. The greater the increase in dissipation energy, the greater the degree of rock damage. The evolution process of the energy dissipation ratio can reflect the internal damage accumulation process of rock well, which can be used as the criterion of rock instability.

The energy applied during breakage is the key to enhancing the magnetite liberation degree and improving quality. The relationship between energy and liberation properties remains unclear due to various complicated factors affecting mineral liberation. Therefore, this work aims to study the effect of energy on the breakage characteristics of magnetite ores; the impact breakage test was conducted on magnetite particle groups at different energies using a drop weight impact tester; the statistical analysis was performed based on the fractal theory to research the particle size distribution; the fracture morphology and liberation properties of these ores were analyzed using scanning electron microscope and mineral liberation analyzer. Results show that the particle size distribution of magnetite after breakage conforms to the fractal law. The larger the energy, the greater the fractal dimension for this distribution, showing a linear relation between them, which implies that the fractal dimension can evaluate the breakage degree. The fracture morphology of magnetite ores indicates that as the energy increases, the intergranular fracture evolves into transgranular fracture, proving the influence of energy on fracture modes. It is found that the magnetite liberation degree first increases and then decreases with the rising of energy, indicating that the magnetite liberation can be improved at an appropriate amount of energy. The above conclusions provide a theoretical reference for optimizing energy and improving broken product quality.