Isolated Bipolar Modular Multilevel DC-DC Converter with Self-balancing Capability for Interconnection of MVDC and LVDC Grids

Bipolar medium-voltage DC(MVDC)and lowvoltage DC(LVDC)grids have the advantages of flexible integration of distributed renewable-energy generation and reliable power supply.In order to achieve voltage conversion,power transfer,and electrical isolation for bipolar MVDC and LVDC grids,a high-power DC-DC converter is essential.Therefore,this paper proposes an isolated bipolar modular multilevel DCDC converter(BiMMDC)with power self-balancing capability for interconnection of MVDC and LVDC grids.The proposed BiMMDC consists of two series connected MMCs in the MV stage to configure a bipolar MVDC interface,and interleaved converters combined with a dual-transformer are designed in the LV stage to configure the bipolar LVDC interface and to provide a self-balancing capability.Equivalent circuits of two series-connected MMCs and a dual-transformer with interleaved converters are derived.After that,operation principles of the proposed BiMMDC are introduced,considering balanced/unbalanced power transfer of bipolar LVDC grid and monopolar shortcircuit or open-circuit faults at MVDC grid.The control scheme is also presented for the proposed BiMMDC under different operating conditions.Finally,a Matlab simulation and controller hardware-in-the-loop(CHIL)evaluation results are provided to validate the feasibility and effectiveness of the proposed typology and its operating performance.

Optical trapping capability of tornado circular Pearcey beams

We systemically investigate optical trapping capability of a kind of tornado waves on Rayleigh particles.Such tornado waves are named as tornado circular Pearcey beams(TCPBs)and produced by combining two circular Pearcey beams with different radii.Our theoretical exploration delves into various aspects,including the propagation dynamics,energy flux,orbital angular momentum,trapping force,and torque characteristics of TCPBs.The results reveal that the orbital angular momentum,trapping force,and torque of these beams can be finely tuned through the judicious manipulation of their topological charges(l_(1)and l_(2)).Notably,we observe a precise control mechanism wherein the force diminishes with|l_(1)+l_(2)|and|l_(1)-l_(2)|,while the torque exhibits enhancement by decreasing solely with|l_(1)+l_(2)|or increasing with|l_(1)-l_(2)|.These results not only provide quantitative insights into the optical trapping performance of TCPBs but also serve as a valuable reference for the ongoing development of innovative photonic tools.

From Knowledge Transfer to Capability Development:The Future of PBL+CBL Teaching Method in Operating Room Nursing Education

Concomitant with the advancement of contemporary medical technology,the significance of perioperative nursing has been increasingly accentuated,necessitating elevated standards for the pedagogy of perioperative nursing.Presently,the PBL(problem-based learning)pedagogical approach,when integrated with CBL(case-based learning),has garnered considerable interest.An extensive literature review has been conducted to analyze the application of the PBL-CBL fusion in the education of perioperative nursing.Findings indicate that this integrative teaching methodology not only enhances students’theoretical knowledge,practical competencies,and collaborative skills but also contributes to the elevation of teaching quality.In conclusion,the PBL-CBL teaching approach holds immense potential for broader application in perioperative nursing education.Nevertheless,it is imperative to continually refine this combined pedagogical strategy to further enhance the caliber of perioperative nursing instruction and to cultivate a greater number of exceptional nursing professionals in the operating room setting.

Robust Tracking Control for Self-balancing Mobile Robots Using Disturbance Observer

In this paper,a robust tracking control scheme based on nonlinear disturbance observer is developed for the self-balancing mobile robot with external unknown disturbances.A desired velocity control law is firstly designed using the Lyapunov analysis method and the arctan function.To improve the tracking control performance,a nonlinear disturbance observer is developed to estimate the unknown disturbance of the self-balancing mobile robot.Using the output of the designed disturbance observer,the robust tracking control scheme is presented employing the sliding mode method for the selfbalancing mobile robot.Numerical simulation results further demonstrate the effectiveness of the proposed robust tracking control scheme for the self-balancing mobile robot subject to external unknown disturbances.

The Development of Self-Balancing Controller for One-Wheeled Vehicles

The purpose of this study is to develop a self-balancing controller (SBC) for one-wheeled vehicles (OWVs). The composition of the OWV system includes: a DSP motion card, a wheel motor, and its driver. In addition, a tilt and a gyro, for sensing the angle and angular velocity of the body slope, are used to realize self-balancing controls. OWV, a kind of unicycle robot, can be dealt with as a mobile-inverted-pendulum system for its instability. However, for its possible applications in mobile carriers or robots, it is worth being further developed. In this study, first, the OWV system model will be derived. Next, through the simulations based on the mathematical model, the analysis of system stability and controllability can be evaluated. Last, a concise and realizable method, through system pole-placement and linear quadratic regulator (LQR), will be proposed to design the SBC. The effectiveness, reliability, and feasibility of the proposal will be con- firmed through simulation studies and experimenting on a physical OWV.

Banana-shaped electron acceptors with an electron-rich core fragment and 3D packing capability

The emergence of Y6-type nonfullerene acceptors has greatly enhanced the power conversion efficiency(PCE)of organic solar cells(OSCs).However,which structural feature is responsible for the excellent photovoltaic performance is still under debate.In this study,two Y6-like acceptors BDOTP-1 and BDOTP-2 were designed.Different from previous Y6-type acceptors featuring an A–D–Aʹ–D–A structure,BDOTP-1,and BDOTP-2 have no electron-deficient Aʹfragment in the core unit.Instead,there is an electron-rich dibenzodioxine fragment in the core.Although this modification leads to a marked change in the molecular dipole moment,electrostatic potential,frontier orbitals,and energy levels,BDOTP acceptors retain similar three-dimensional packing capability as Y6-type acceptors due to the similar banana-shaped molecular configuration.BDOTP acceptors show good performance in OSCs.High PCEs of up to 18.51%(certified 17.9%)are achieved.This study suggests that the banana-shaped configuration instead of the A–D–Aʹ–D–A structure is likely to be the determining factor in realizing high photovoltaic performance.

Research on Self-balancing Two Wheels Mobile Robot Control System Analysis

The paper presents the research on self-balancing two-wheels mobile robot control system analysis with experimental studies.The research problem in this work is to stabilize the mobile robot with self-control and to carry the sensitive things without failing in a long span period.The main objective of this study is to focus on the mathematical modelling of mobile robot from laboratory scale to real world applications.The numerical expression with mathematical modelling is very important to control the mobile robot system with linearization.The fundamental concepts of dynamic system stability were utilized for maintaining the stability of the constructed mobile robot system.The controller design is also important for checking the stability and the appropriate controller design is proportional,integral,and derivative-PID controller and Linear Quadratic Regulator(LQR).The steady state error could be reduced by using such kind of PID controller.The simulation of numerical expression on mathematical modeling was conducted in MATLAB environments.The confirmation results from the simulation techniques were applied to construct the hardware design of mobile robot system for practical study.The results from simulation approaches and experimental approaches are matched in various kinds of analyses.The constructed mobile robot system was designed and analyzed in the control system design laboratory of Yangon Technological University(YTU).

Motor Learning Based on the Cooperation of Cerebellum and Basal Ganglia for a Self-Balancing Two-Wheeled Robot

A novel motor learning method is present based on the cooperation of the cerebellum and basal ganglia for the behavior learning of agent. The motor learning method derives from the principle of CNS and operant learning mechanism and it depends on the interactions between the basal ganglia and cerebellum. The whole learning system is composed of evaluation mechanism, action selection mechanism, tropism mechanism. The learning signals come from not only the Inferior Olive but also the Substantia Nigra in the beginning. The speed of learning is increased as well as the failure time is reduced with the cerebellum as a supervisor. Convergence can be guaranteed in the sense of entropy. With the proposed motor learning method, a motor learning system for the self-balancing two-wheeled robot has been built using the RBF neural networks as the actor and evaluation function approximator. The simulation experiments showed that the proposed motor learning system achieved a better learning effect, so the motor learning based on the coordination of cerebellum and basal ganglia is effective.

Experimental study of the temporary plugging capability of diverters to block hydraulic fractures in high-temperature geothermal reservoirs

The effective plugging of artificial fractures is key to the success of temporary plugging and diverting fracturing technology,which is one of the most promising ways to improve the heat recovery efficiency of hot dry rock.At present,how temporary plugging agents plug artificial fractures under high temperature remains unclear.In this paper,by establishing an improved experimental system for the evaluation of temporary plugging performance at high temperature,we clarified the effects of high temperature,injection rate,and fracture width on the pressure response and plugging efficiency of the fracture.The results revealed that the temporary plugging process of artificial fractures in hot dry rock can be divided into four main stages:the initial stage of temporary plugging,the bridging stage of the particles,the plugging formation stage,and the high-pressure dense plugging stage.As the temperature increases,the distribution distance of the temporary plugging agent,the number of pressure fluctuations,and the time required for crack plugging increases.Particularly,when the temperature increases by 100℃,the complete plugging time increases by 90.7%.

Sb-Cu alloy cathode with a novel lithiation mechanism of ternary intermetallic formation: Enabling high energy density and superior rate capability of liquid metal battery

Antimony(Sb) is an attractive cathode for liquid metal batteries(LMBs) because of its high theoretical voltage and low cost.The main obstacles associated with the Sb-based cathodes are unsatisfactory energy density and poor rate-capability.Herein,we propose a novel Sb_(64)Cu_(36)cathode that effectively tackles these issues.The Sb_(64)Cu_(36)(melting point:525℃) cathode presents a novel lithiation mechanism involving sequentially the generation of Li_(2)CuSb,the formation of Li_(3)Sb,and the conversion reaction of Li_(2)CuSb to Li_(3)Sb and Cu.The generated intermetallic compounds show a unique microstructure of the upper floated Li_(2)CuSb layer and the below cross-linked structure with interpenetrated Li_(2)CuSb and Li_(3)Sb phases.Compared with Li_(3)Sb,the lower Li migration energy barrier(0.188 eV) of Li_(2)CuSb significantly facilitates the lithium diffusion across the intermediate compounds and accelerates the reaction kinetics.Consequently,the Li‖Sb_(64)Cu_(36)cell delivers a more excellent electrochemical performance(energy density:353 W h kg^(-1)at 0.4 A cm^(-2);rate capability:0.59 V at 2.0 A cm^(-2)),and a much lower energy storage cost of only 38.45 $ kW h^(-1)than other previously reported Sb-based LMBs.This work provides a novel cathode design concept for the development of high-performance LMBs in applications for large-scale energy storage.

考虑碳流约束的电力系统能碳安全域模型与计算方法

针对当前电力系统碳减排任务与安全稳定运行需求,研究电力系统低碳安全运行技术。现有的能量流安全域模型使电力系统安全监视与控制更加科学有效,但忽略了系统运行过程中可能存在的“高碳”风险。文中提出了一种考虑碳流约束的电力系统能碳耦合安全域(简称能碳安全域)模型与计算方法,旨在保证系统安全性的同时减排提效。为完整刻画电力系统的低碳运行能力极限,分别从负荷端和源端角度提出了考虑碳流约束的系统最大供电能力曲线及最大消纳能力曲线模型。基于系统最大供电能力工作点,提出了能碳安全边界仿真拟合计算方法,实现了能碳安全域的降维观测。最后,结合算例验证了所提模型的有效性。

企业数字化能力影响因素分析——以广东省制造业为例

制造业是我国国民经济的重要组成部分,随着新一代信息技术和数字技术的迅猛发展,民众日益增长的智能化需求和数字化市场趋势推动着企业不断探索和构建自身的数字化能力来实现数字化转型,进而获取持续的竞争优势。本文基于动态能力理论和TOE分析框架,以广东省制造业为例,设计了企业数字化能力的研究模型,并提出假设,在对模型和假设的不同影响路径进行实证检验和修正后,分析了组织结构、高层管理者和数字技术能力对广东省制造企业数字化能力构建的作用机理。

计及灾后恢复全过程储能应急响应能力的配电网韧性规划

储能因响应快、灵活性高的特点,已成为可再生能源发展必不可少的支撑技术,不仅具有削峰填谷、改善电能质量的作用,在灾后恢复过程中的应急响应能力同样不可忽视。提出了一种计及灾后恢复全过程储能应急响应能力的配电网韧性规划方法,构建了同时考虑网架增强和储能配置策略的配电网韧性增强双层规划模型,系统地刻画了极端灾害发生后配电网网架重构、设备抢修及复电等灾后恢复全过程的源-网-荷-储互动模式场景。最后,通过IEEE33节点系统的算例分析表明,所提方法能更充分地挖掘储能的应急响应潜力,有效提高增强性规划决策的精准度,获得更佳的投资回报。

数字化转型与企业国际化绩效研究——基于供应链能力的中介作用

本文借助Python爬虫技术刻画上市公司数字化转型强度,利用2012—2021年A股上市公司和国泰安数据库相关匹配数据,从理论和实证两个方面探讨数字化转型对企业国际化绩效的影响及其作用机理。研究结果表明,数字化转型对企业国际化绩效具有显著的促进作用且通过一系列内生性和稳健性检验,供应链能力在其中发挥了中介效应。进一步分析发现,数字化转型对企业国际化绩效的提升效果在非国有企业、技术和资本密集型行业、发达国家或地区更明显。这一结论对促进企业实现数字化转型、提升国际化绩效、增强国际竞争力具有重要的现实意义。

制造企业数字创新如何促进企业绩效提升

为探究制造企业数字创新促进企业绩效提升的过程机理,揭示数字创新的协同效应、扩散效应和增值效应,以及数字化投入持续性的情境效应,将数字创新划分为效率型、新颖型和融合型3种类型,并将数字化能力划分为数字协同能力、数字创新扩散能力和数字价值化能力3个维度,以251家中国制造企业为调查对象进行实证检验,结果发现,第一,数字创新能够显著提升企业绩效水平。第二,数字创新通过推动数字化能力重构促进企业绩效水平提升。第三,不同类型数字化能力在数字创新与企业绩效间发挥中介作用。具体表现如下:数字创新扩散能力在新颖型数字创新与企业绩效间发挥中介作用;数字价值化能力在融合型数字创新与企业绩效间发挥中介作用。第四,数字化投入持续性在企业数字创新过程中发挥重要调节作用,正向调节数字创新与企业绩效间关系,强化数字创新与数字化能力间关系,以及效率型数字创新与数字协同能力间关系。结论可为制造企业数字创新提供理论指导与实践启示。

高校图书馆科研数据管理服务能力评价指标体系研究

本文通过对相关文献和主流模型的梳理,从形式、内容、效用三个维度构建高校图书馆科研数据管理服务能力评价指标体系,并通过一系列科学验证,最终得到由机构支撑力、管理服务力、社会效应力3个一级指标,经费资源支撑、数据资源管理、用户素养教育、学术影响力等11个二级指标,成本效益分析、数据使用规范、用户素养教育内容、科研成果产出等35个三级指标构成的指标体系。构建高校图书馆科研数据管理服务能力评价指标体系,在为国内实践研究提供评价工具的同时,也可以促进高校图书馆科研数据管理服务规范化发展。

中小企业数字化转型的路径探析

加快推动中小企业数字化转型是数字经济发展的重要基础。由于缺乏足够的技术与资源,中小企业数字化转型需依附第三方数字平台完成产品体系、组织结构、业务流程的改造,进而降低成本、提升效率。其数字化转型过程为企业层面的数字技术部分采用、行业层面的数字技术整体融合以及生态层面的数字技术共生发展。但中小企业在数字化转型过程中,还面临数字意识薄弱、转型能力不足、转型资源受限、转型数据欠缺、转型成本过高等诸多困境。中小企业要立足推动数字经济发展的战略要求,从培养动态管理能力、运用轻体量数字平台、提升组织使用信息技术的能力、获得政府外部帮扶及支持等方面创新路径,推动数字化转型。

急诊科护士突发公共卫生事件心理弹性培训方案的构建与初步应用研究

目的构建基于Kumpfer心理弹性框架理论与国际心理弹性研究计划项目组(the International Resilience Research Project,IRRP)心理弹性训练策略的心理弹性培训方案,探讨其在急诊科护士突发公共卫生事件下的应用效果。方法2022年1-6月,采用简单随机抽样法选择上海市某三级医院的急诊科护士为研究对象,按随机数字表分为对照组和观察组各30例,对照组采用常规培训和管理方法,观察组在对照组的基础上实施心理弹性培训方案。评价并比较两组护士干预前后心理弹性及应急能力的变化。结果干预后,观察组护士的心理弹性、应急能力得分均高于对照组(均P<0.05)。结论心理弹性培训方案在突发公共卫生事件下能有效提升急诊科护士的心理弹性水平,保障突发公共卫生事件应急处置工作有序开展。

针灸推拿学专业研究生创新能力培养问题与对策

针灸推拿学作为中医学的一门传统优势学科,国家和社会对其创新型研究人才的需求日益迫切。文章分析了目前针灸推拿学专业研究生创新能力的培养现状,从师和生共创的两个角度探讨应对策略,旨在深化针灸推拿学专业研究生教育改革,提高本专业研究生培养质量,培养符合时代特征的、素质全面的针灸推拿学创新型研究人才。

数字化转型背景下中小制造企业如何编排资源利用数字机会——基于资源编排理论的fsQCA研究

利用数字机会是中小制造企业实现数字化转型的关键。资源编排理论指出,利用数字机会离不开企业资源和能力的支持,尤其要将各种资源和能力有效组合起来。但大量中小制造企业难以有效编排自身资源和能力来利用数字机会。为此,本文关注中小制造企业的五种传统资源和能力(实物资源、关系资源、制造能力、营销能力和创新能力)及两种数字资源和能力(大数据资源和数字平台能力),运用模糊集定性比较分析(fsQCA)方法对392份问卷数据进行分析,研究发现:五种传统资源和能力及两种数字资源和能力都不能单独作为中小制造企业数字机会利用的必要条件,但数字平台能力作为核心条件能发挥较为普适的作用。同时,中小制造企业的数字机会利用存在三种路径,可归纳为“内向型”“外向型”和“内外兼顾型”,通过进一步聚焦高技术制造业,发现其数字机会利用存在两种路径:“渐进型”和“突破型”。本文有助于发现如何在数字化背景下编排企业资源和能力,拓展了资源编排理论的研究情境(数字化背景)和研究范围(数字资源和能力),回应了识别“数据时代的资源编排规律”的呼吁。