Simulation Analysis of Deformation Control for Magnetic Soft Medical Robots

Dear Editor,This letter presents a biocompatible cross-shaped magnetic soft robot and investigates its deformation mode control strategy through COMSOL modeling and simulation.Magnetic soft robots offer novel avenues for precise treatment within intricate regions of the human body.

From Simulation to Reality: A Comprehensive Study on the Efficacy of a Rotating Monopolar and Bipolar Radiofrequency System through In-Silico Modeling and Pre-Clinical and Clinical Validation

Background: Skin aging is an unavoidable process aggravated by environmental agents. Among other energy devices, non-invasive radiofrequency (RF) technology is widely used for skin tightening and body contouring as it is simpler and more affordable than other technologies that also minimize pain and side-effects. However, most of the current RF devices do not provide automatic skin temperature control and it is difficult to achieve controlled, deep, and harmless thermal increase, so treatment performance and safety is dependent on the operator’s movements and expertise. Objective: To show the potential of numerical simulations for optimizing the design of monopolar and bipolar RF electrodes that are capable of providing homogeneous, deep and controlled heating. Materials and methods: In-silico models were developed and analyzed using Comsol Multiphysics software to simulate the RF effect produced in tissue by rotating monopolar and bipolar electrodes with different geometries from the Sculpt & Shape RF device (Sinclair, Spain), operating at frequencies of 0.5 and 1 MHz. Ex-vivo and in-vivo proof-of-concept tests were carried out to validate the simulations. Finally, treatments were performed on 16 subjects and a total of 78 body areas to assess the clinical results generated by the RF electrodes for skin tightening and body contouring. Results: In-silico studies emulated the superficial and deep dispersion of heat due to the release of RF energy into human skin tissue. The rotating electrodes (monopolar and bipolar) and the selected RF frequency (0.5 and 1 MHz) determined the homogeneity of the thermal distribution, the penetration depth (between 4.37 mm and 25.0 mm) and the heating dynamics (between 30 and 100 seconds to reach the target skin temperature), which were confirmed by ex-vivo and in-vivo tests. In addition, real treatments on facial and body areas using skin temperatures of between 43˚C and 44˚C showed consistent results with good clinical efficacy for skin tightening, circumference reduction and cellulite reduction, with no adverse effects and high subject satisfaction. Conclusions: New monopolar and bipolar RF electrodes with rotating technology have been designed and optimized using numerical simulations. The use of in-silico studies and accurate models that reproduce the thermal behavior of human biological tissues can be used to better understand RF devices and to develop superior, efficient, and safer products more quickly.

Integrated Experimental and Simulation Investigation of Breakdown Voltage Characteristics Across Electrode Configurations in SF_(6) Circuit Breakers

This study investigates the breakdown voltage characteristics in sulfur hexafluoride(SF6)circuit breakers,employing a novel approach that integrates both experimental investigations and finite element simulations.Utilizing a sphere-sphere electrode configuration,we meticulously measured the relationship between breakdown voltage and electrode gap distances ranging from 1 cm to 4.5 cm.Subsequent simulations,conducted using COMSOL Multiphysics,mirrored the experimental setup to validate the model’s accuracy through a comparison of the breakdown voltage-electrode gap distance curves.The simulation results not only aligned closely with the experimental data but also allowed the extraction of detailed electric field strength,electric potential contours,and electric current flow curves at the breakdown voltage for gap distances extending from 1 to 4.5 cm.Extending the analysis,the study explored the electric field and potential distribution at a constant voltage of 72.5 kV for gap distances between 1 to 10 cm,identifying the maximum electric field strength.A comprehensive comparison of five different electrode configurations(sphere-sphere,sphere-rod,sphere-plane,rod-plane,rod-rod)at 72.5 kV and a gap distance of 1.84 cm underscored the significant influence of electrode geometry on the breakdown process.Moreover,the research contrasts the breakdown voltage in SF6 with that in air,emphasizing SF6’s superior insulating properties.This investigation not only elucidates the intricate dynamics of electrical breakdown in SF6 circuit breakers but also contributes valuable insights into the optimal electrode configurations and the potential for alternative insulating gases,steering future advancements in high-voltage circuit breaker technology.

基于Comsol软件的电磁兼容课程案例式教学设计

该文介绍基于Comsol软件的电磁兼容课程案例式教学方法。通过案例教学和仿真,学生将理论知识应用于实际问题,深入理解电磁兼容的概念和原理。通过仿真案例的可视化结果,学生直观地理解电磁辐射和传导,观察不同参数对电磁兼容性的影响。结果表明,仿真案例具有直观性和可视化等优势,同时又有简化模型、缺乏实际操作经验和对计算机的依赖等局限性。在设计仿真案例时,要充分发挥其优势,规避不足,为学生的学习提供实践性、直观性和灵活性,培养学生的工程设计与研发能力。

间歇和连续喷灌下土壤水分运动特征COMSOL数值模拟与验证

为探明间歇喷灌和连续喷灌条件下的土壤水分运动规律,建立喷灌随时间变化的非均匀灌水边界下的土壤水分二维运动模型,借助COMSOL数值模拟软件,实现模型的求解,并通过土箱试验对模型进行验证,分析不同喷灌模式下土壤水分运动特征,评估喷灌均匀性和喷灌模式对土壤含水率均匀性的影响。结果表明,土壤含水率和土壤湿润峰模拟值与实测值之间的一致性较好。喷灌模式对土壤水分运动过程和含水率均匀度影响不大。随着间歇次数和间歇时长的增加,喷灌结束时表层土壤含水率减小、水分入渗深度增加。喷灌条件下,土壤含水率均匀度高于地表测得的喷灌均匀度。当喷灌均匀度为39.77%~80.15%时,土壤含水率均匀度为88.57%~94.47%。当喷灌均匀度较低、点喷灌强度较高、总灌水量较大时,采用间歇喷灌、增加间隙次数和总间歇时长,可以一定程度降低地表径流和深层渗漏风险、改善土壤含水率均匀性。研究可为喷灌系统设计均匀度合理取值和高效运行提供理论基础。

一种基于COMSOL的四极场离子运动仿真模型

四极场质谱仪是目前应用最广泛的小型质谱仪器之一。研究四极场中离子运动轨迹,对于深入理解和认识四极场中离子的行为非常重要,不仅有助于提出新的质谱技术问题,也对质谱仪器研制具有指导意义。离子运动的数值模拟和仿真是研究四极杆中离子运动行为的高效数字化手段。本文基于COMSOL Multiphysics建立了四极场的数字仿真模型Sim-Quaq-COM-V1.0,应用该模型得到的仿真数据结果与理论计算结果一致,可作为研究四极场中离子行为的精确数字化模型。在此基础上,对比研究了双曲四极杆与圆柱四极杆中离子的运动行为,相同条件下,m/z 69离子在双曲四极场中通过的数量约为圆柱四极场的4倍。该仿真计算模型能够快速配置全局参数,节省几何设计和建模的时间,降低计算难度;模型支持并行计算技术,在计算速度和计算量方面均有大幅提升,能够同时处理大量离子,缩短研究周期,助力质谱仪器设计和研发技术的数字化发展。

基于Simulink和Comsol联合仿真的虚拟热试验系统

通过Simulink和Comsol软件联合仿真搭建虚拟热试验系统,实现热试验的完全虚拟化;利用联合仿真技术,实现对控制系统、电场、热场的综合仿真分析;可一次性直接观测各个观测点数据状态,包括功放输出状态信息、加热器输出状态信息及被试件热热状态信息。虚拟热试验系统对工程热试验具有预示和指导作用,可以实现超出现有热环境地面模拟能力的热环境模拟,为型号的研制提供依据。

COMSOL Multiphysics在锂离子电池中的应用

作为一种具有前景的能量存储系统,锂离子电池需要进一步提高能量密度、功率密度、可靠性和循环稳定性,以满足不断增长的大型能源存储、电动汽车和便携式电子设备需求。当前对锂离子电池的实验研究仍然面临多个挑战,这些挑战包括电解液的导电性和安全性、高能量负极的沉积-剥离机制的优化、高能量正极的循环电压和容量维持、高电流条件下的界面极化和容量释放,以及在极端电流-温度-针刺条件下的热失控管理等问题。这些问题涉及到电-化-力-热等多个场的耦合作用,需要进行协同优化处理。COMSOL Multiphysics提供了一种可行的工具,通过求解多物理场耦合的连续方程,能够同时考虑载流子浓度、电流密度、电-化学势、温度、应力/应变和几何形态等综合信息的演化。本文概述了该工具在锂离子电池的电解液、负极和正极设计等方面的研究,并聚焦于多场耦合对电池性能的综合影响、多场耦合模拟方法以及理论模拟与实验表征的结合。最后,本文对理论与实验联合研究中的多场和多尺度问题进行了展望。

基于COMSOL仿真的脉冲电流激励下电动汽车动力电池热特性研究

随着电动汽车的快速发展,锂离子电池作为电动汽车主要动力来源,其综合性能受到越来越多的关注。而在低温环境下动力电池性能衰减严重,影响电动汽车在北方寒冷地区的发展和普及。低温预热技术作为电池热管理系统的核心技术之一,可以有效缓解动力电池在低温环境下的性能衰减。文章通过试验得到电池的基本参数,基于COMSOL仿真软件搭建了电池脉冲加热模型,探究电池在加热过程中温升速率的变化以及模组温度分布情况。研究结果表明:在低温环境下,脉冲加热可以有效提高电池的温度。在加热过程中,电池模组内温度分布均匀,平均温差为0.55℃,整体呈现出温度向电池模组中心聚集的趋势。此外,还将脉冲电流加热与电加热膜加热的加热效果作了对比,验证了脉冲加热的加热效果和温度一致性都优于电加热膜加热法。

基于COMSOL Multiphysics的经皮心肌内室间隔射频消融仿真模型构建及应用

目的:构建一种经皮心肌内室间隔射频消融仿真模型,探究不同激励电压、不同消融时间对消融区域的影响。方法:以梗阻性肥厚型心肌病患者的术前CT数据为基础,利用Mimics软件实现心脏各区域组织的分割与三维表面重建,通过SolidWorks软件将重建后的各部分转化为三维实体模型,并将其与在COMSOL Multiphysics仿真软件中建立的电极针结构结合在一起,得到梗阻性肥厚型心肌病的经皮心肌内室间隔射频消融仿真模型。基于该模型设置电磁、热多物理场边界条件,并对组织温度分布以及消融时间、激励电压对消融区域的影响进行仿真分析。结果:利用该模型可以实现经皮心肌内室间隔射频消融的仿真分析,且不同的激励电压、不同的消融时间对有效消融区域具有明显的影响。结论:构建的经皮心肌内室间隔射频消融仿真模型为后续开展多种因素对消融结局的影响提供了模型基础,对进一步研究实际临床治疗中的参数优化具有重要意义。

基于COMSOL的普朗铜矿裂隙渗流数值模拟

为了补充普朗铜矿地质特征研究以及探明矿区裂隙渗流特征,基于COMSOL软件对普朗铜矿裂隙渗流进行数值模拟。通过人工测窗法、三维激光扫描法和数字式全景钻孔摄像法对矿区的节理裂隙进行全面测量,调查开采前后矿区岩体裂隙张开度、倾向倾角、分布特征等情况。利用Monte-Carlo法生成裂隙网络模型并导出矿区岩体裂隙的几何参数,用COMSOL软件对普朗铜矿中裂隙进行渗流数值模拟。模拟结果得出,矿区的孔隙率为2.56%,渗透系数为6.52×10^(-8)m/s,对普朗铜矿的开采和资源评估具有重要意义,为其他类似矿山中裂隙渗流的数值模拟提供借鉴。

基于COMSOL和MATLAB的近轴光学隐形的研究

基于矩阵光学原理实现透镜组近轴光出现隐形区域,探究了不同参数的透镜对光学隐形区域的影响;采取正交实验设计,分别使用MATLAB和COMSOL对隐形区域进行了数值模拟,对比得出了隐形区域的影响因素,并进行了可视化呈现。结果表明,透镜的焦距和半径影响隐形区域,当透镜的直径不变时,若透镜的焦距为f,此时隐形区域t_(1)和隐形区域t_(2)的体积之和最小,当透镜的焦距小于f时,透镜的焦距与隐形范围呈负相关;当透镜的焦距大于f时,透镜的焦距与隐形范围呈正相关;当透镜的焦距不变时,透镜的直径与隐形范围呈正相关。各个透镜参数对隐形区域的体积的影响因素排序为:焦距f_(2)>直径h_(1)>直径h_(2)>焦距f_(1)。研究结果对于深入理解光学隐形区域的形成及其受透镜参数调节的影响具有重要的意义。

基于COMSOL的井下电磁式能量阻隔器设计及分析

为改善页岩频谱共振装置由于作业空间开放而导致的能量利用率较低的问题,对井下电磁式能量阻隔器进行设计及分析。基于工程电磁场理论及非线性有限元算法,并通过COMSOL Multiphysics软件对井下电磁式能量阻隔器的磁场分布及运行过程进行分析,最后通过仿真结果验证井下电磁式能量阻隔器设计的可行性及正确性,并初步研制电磁式能量阻隔器上封隔部分样机。该研究在提高学生理论分析及仿真能力的同时,使学生对电磁式装置的设计及分析有一个更为直观、全面的认识。

基于COMSOL Multiphysics 软件的地下水污染物运移模拟研究

地下水环境质量是衡量生态文明建设水平的重要指标,应用科学有效的计算方法模拟地下水污染物渗漏的影响范围及程度,对于地下水污染的防治有着极其重要的意义。COMSOL Multiphysics作为一款多物理场建模与仿真软件,能够较好地结合现实水文地质条件,有效地模拟自然界一些水文地质过程发生和发展过程,对进行以预防和修复治理为目的的地下水污染物数值模拟预测具有十分重要的应用价值。本文根据研究区的水文地质特征,利用COMSOL Multiphysics软件构建了地下水数值模型,对研究区地下水污染物运移规律进行分析,对污染物运移轨迹进行模拟与预测。预测结果表明,氯仿、石油烃污染物在释放1 000 a时的影响范围分别是6.3×10^(6)m^(2)和5.7×10^(6)m^(2)。由于地下水流速相对较慢,污染物扩散速度极其缓慢,研究区内污染物需要在百年时间量级上才可能形成较大规模扩散,短期内对地下水环境的污染风险较小。模拟结果为研究区的地下水环境评价和防范措施提供了科学依据。

基于COMSOL-PHREEQC的CO_(2)+O_(2)地浸采铀反应运移数值模拟

铀资源是的世界上重要的战略资源,如何安全高效开发利用铀资源,对保障国家能源供应和国家战略安全意义重大。CO_(2)+O_(2)地浸采铀是砂岩型铀矿采冶的主要方式,研究CO_(2)+O_(2)溶浸过程中水动力场和化学场的耦合机制是预测地浸采铀过程中铀动态浸出的关键核心。以内蒙古某煤铀共存矿床为对象,通过COMSOL构建地浸过程中溶质运移的对流与弥散模型,通过PHREEQC构建砂岩型铀矿CO_(2)+O_(2)溶浸过程的热力学数据库,利用iCP平台(Interface COMSOL-PHREEQC)建立COMSOL-PHREEQC耦合框架的CO_(2)+O_(2)地浸采铀的反应运移数值模型,模拟了CO_(2)+O_(2)地浸过程中铀矿动态浸出过程。同时,基于参数敏感性分析定量比较了不同参数对铀浸出效果影响的重要性程度。研究结果表明,本模型能够模拟预测CO_(2)+O_(2)溶浸过程中铀的反应运移过程。模拟结果发现CO_(2)+O_(2)地浸采铀过程中,抽、注液孔周围水动力强,溶浸液与铀矿物发生强烈的化学反应,形成高浓度的铀区;在水动力作用弱的地方,溶浸液不能及时到达,形成低浓度铀区。浸出铀的运移过程主要受对流和弥散作用控制。浸出铀可以通过下部煤层采动裂缝进入采煤工作面和采空区内,影响煤矿安全开采活动。参数敏感性分析结果揭示抽液流量、CO_(2)和O_(2)体积分数是铀浸出率的关键控制因素,而铀的浸出率与地层渗透率、地下水流速之间并不是呈单调的递增关系。研究结果对砂岩型铀矿CO_(2)+O_(2)地浸开采具有一定的指导作用。

A study of fire propagation in coal seam with numerical simulation of heat transfer and chemical reaction rate in mining field

Spontaneous combustion of coal is a problem that affects the mining operation and generates environ-mental,economic,social and geotechnical impacts.This phenomenon has been divided into two pro-cesses:ignition and propagation.Fire propagation develops in coal seams because of a set of factors such as direction and wind speed,fracturing and temperature.In this work,heat transfer and chemical kinetics are studied from conservation equations of energy and species,respectively,using the software COMSOL Multiphysics to simulate the propagation of fires in coal seams.Two possible scenarios were analyzed that usually occur in the walls of the coal seams,such as fire focus and fire complete screens.It was found that the propagation kinetics of the fire changes depending on the temperature,the fractur-ing of rock mass and the area of fire influence.For temperature values lower than 300℃,there is con-sumption around 250 cm^3/h,values around 700℃,the consumption is 1500 cm^3/h,and for fires of 1200℃ have values of 3000 cm^3/h.Depending on the speed of propagation can vary from 4 to 17cm/day,considering on the level and fracturing of the final wall of the open pit.

Numerical simulation of enhancing coalbed methane recovery by injecting CO_2 with heat injection

The technology used to enhance coalbed methane(CBM) recovery by injecting CO_2(CO_2-ECBM) with heat, combining heat injection with CO_2 injection, is still in its infancy; therefore, theoretical studies of this CO_2-ECBM technology should be perused. First, the coupling equations of the di usion–adsorption–seepage–heat transfer fields of gas are established. The displacement processes under di erent pressures and temperatures are simulated by COMSOL. Finally, the displacement effects, a comparison of the CO_2 storage capacity with the CH_4 output and the e ective influencing radius of CO_2 injection are analyzed and discussed. The results show that(1) the displacement pressure and temperature are two key factors influencing the CH_4 output and the CO_2 storage capacity, and the increase in the CO_2 storage capacity is more sensitive to temperature and pressure than the CH_4 output.(2) The gas flow direction is from the injection hole to the discharge hole during the displacement process, and the regions with high velocity are concentrated at the injection hole and the discharge hole.(3) A reduction in the CH_4 concentration and an increase in the CO_2 concentration are obvious during the displacement process.(4) The e ective influencing radius of injecting CO_2 with heat increases with the increase in time and pressure. The relationship between the e ective influencing radius and the injection time of CO_2 has a power exponential function, and there is a linear relationship between the functional coe cient and the injection pressure of CO_2. This numerical simulation study on enhancing CBM recovery by injecting CO_2 with heat can further promote the implementation of CO_2-ECBM project in deep coal seams.

Simulation of microwave’s heating effect on coal seam permeability enhancement

As hydraulic fracturing was forbidden in some countries due to possible negative environmental impacts and enhanced coalbed methane(ECBM)was restricted by in-situ conditions,microwave heating was proposed to enhance coalbed permeability.One of the mechanisms of improving coal permeability with microwave irradiation is that thermal expansion caused by microwave heating.To study the influence of microwave’s heating effect of coal samples,the simulations were conducted using a coupled electromagnetic,thermal and mechanical model in this paper.The temperature,Von-Mises stress and strain distribution of coal sample are recorded every 10 s.The permeability distribution is also obtained based on the relationship between strain and permeability from articles.It was found that volume average temperature,stress,strain and permeability increase almost linearly with time.The average permeability increased from 1.65 10×16 m^2 to 3.63 10×16 m^2 under 2.45 GHz and 500Wmicrowave radiation after 300 s.The significant increase proved microwave to be effective in coal seam permeability enhancement.

Three-dimensional spatial structure of the macro-pores and flow simulation in anthracite coal based on X-ray μ-CT scanning data

The three-dimensional(3 D) structures of pores directly affect the CH4 flow.Therefore,it is very important to analyze the3 D spatial structure of pores and to simulate the CH4 flow with the connected pores as the carrier.The result shows that the equivalent radius of pores and throats are 1-16 μm and 1.03-8.9 μm,respectively,and the throat length is 3.28-231.25 μm.The coordination number of pores concentrates around three,and the intersection point between the connectivity function and the X-axis is 3-4 μm,which indicate the macro-pores have good connectivity.During the single-channel flow,the pressure decreases along the direction of CH4 flow,and the flow velocity of CH4 decreases from the pore center to the wall.Under the dual-channel and the multi-channel flows,the pressure also decreases along the CH4 flow direction,while the velocity increases.The mean flow pressure gradually decreases with the increase of the distance from the inlet slice.The change of mean flow pressure is relatively stable in the direction horizontal to the bedding plane,while it is relatively large in the direction perpendicular to the bedding plane.The mean flow velocity in the direction horizontal to the bedding plane(Y-axis) is the largest,followed by that in the direction horizontal to the bedding plane(X-axis),and the mean flow velocity in the direction perpendicular to the bedding plane is the smallest.

Diagnostic of capacitively coupled radio frequency plasma from electrical discharge characteristics：comparison with optical emission spectroscopy and fluid model simulation

The capacitively coupled radio frequency（CCRF）plasma has been widely used in various fields.In some cases,it requires us to estimate the range of key plasma parameters simpler and quicker in order to understand the behavior in plasma.In this paper,a glass vacuum chamber and a pair of plate electrodes were designed and fabricated,using 13.56 MHz radio frequency（RF）discharge technology to ionize the working gas of Ar.This discharge was mathematically described with equivalent circuit model.The discharge voltage and current of the plasma were measured atdifferent pressures and different powers.Based on the capacitively coupled homogeneous discharge model,the equivalent circuit and the analytical formula were established.The plasma density and temperature were calculated by using the equivalent impedance principle and energy balance equation.The experimental results show that when RF discharge power is 50–300 W and pressure is 25–250 Pa,the average electron temperature is about 1.7–2.1 e V and the average electron density is about 0.5？×10^17–3.6？×10^17m^-3.Agreement was found when the results were compared to those given by optical emission spectroscopy and COMSOL simulation.