Multilevel analysis of the central-peripheral-target organ pathway:contributing to recovery after peripheral nerve injury

Peripheral nerve injury is a common neurological condition that often leads to severe functional limitations and disabilities.Research on the pathogenesis of peripheral nerve injury has focused on pathological changes at individual injury sites,neglecting multilevel pathological analysis of the overall nervous system and target organs.This has led to restrictions on current therapeutic approaches.In this paper,we first summarize the potential mechanisms of peripheral nerve injury from a holistic perspective,covering the central nervous system,peripheral nervous system,and target organs.After peripheral nerve injury,the cortical plasticity of the brain is altered due to damage to and regeneration of peripheral nerves;changes such as neuronal apoptosis and axonal demyelination occur in the spinal cord.The nerve will undergo axonal regeneration,activation of Schwann cells,inflammatory response,and vascular system regeneration at the injury site.Corresponding damage to target organs can occur,including skeletal muscle atrophy and sensory receptor disruption.We then provide a brief review of the research advances in therapeutic approaches to peripheral nerve injury.The main current treatments are conducted passively and include physical factor rehabilitation,pharmacological treatments,cell-based therapies,and physical exercise.However,most treatments only partially address the problem and cannot complete the systematic recovery of the entire central nervous system-peripheral nervous system-target organ pathway.Therefore,we should further explore multilevel treatment options that produce effective,long-lasting results,perhaps requiring a combination of passive(traditional)and active(novel)treatment methods to stimulate rehabilitation at the central-peripheral-target organ levels to achieve better functional recovery.

Multilevel carbon architecture of subnanoscopic silicon for fast‐charging high‐energy‐density lithium‐ion batteries

Silicon(Si)is widely used as a lithium‐ion‐battery anode owing to its high capacity and abundant crustal reserves.However,large volume change upon cycling and poor conductivity of Si cause rapid capacity decay and poor fast‐charging capability limiting its commercial applications.Here,we propose a multilevel carbon architecture with vertical graphene sheets(VGSs)grown on surfaces of subnanoscopically and homogeneously dispersed Si–C composite nanospheres,which are subsequently embedded into a carbon matrix(C/VGSs@Si–C).Subnanoscopic C in the Si–C nanospheres,VGSs,and carbon matrix form a three‐dimensional conductive and robust network,which significantly improves the conductivity and suppresses the volume expansion of Si,thereby boosting charge transport and improving electrode stability.The VGSs with vast exposed edges considerably increase the contact area with the carbon matrix and supply directional transport channels through the entire material,which boosts charge transport.The carbon matrix encapsulates VGSs@Si–C to decrease the specific surface area and increase tap density,thus yielding high first Coulombic efficiency and electrode compaction density.Consequently,C/VGSs@Si–C delivers excellent Li‐ion storage performances under industrial electrode conditions.In particular,the full cells show high energy densities of 603.5 Wh kg^(−1)and 1685.5 Wh L^(−1)at 0.1 C and maintain 80.7%of the energy density at 3 C.

On the Use of Monotonicity-Preserving Interpolatory Techniques in Multilevel Schemes for Balance Laws

Cost-effective multilevel techniques for homogeneous hyperbolic conservation laws are very successful in reducing the computational cost associated to high resolution shock capturing numerical schemes.Because they do not involve any special data structure,and do not induce savings in memory requirements,they are easily implemented on existing codes and are recommended for 1D and 2D simulations when intensive testing is required.The multilevel technique can also be applied to balance laws,but in this case,numerical errors may be induced by the technique.We present a series of numerical tests that point out that the use of monotonicity-preserving interpolatory techniques eliminates the numerical errors observed when using the usual 4-point centered Lagrange interpolation,and leads to a more robust multilevel code for balance laws,while maintaining the efficiency rates observed forhyperbolic conservation laws.

Stock trend prediction method coupled with multilevel indicators

To systematically incorporate multiple influencing factors,the coupled-state frequency memory(Co-SFM)network is proposed.This model integrates Copula estimation with neural networks,fusing multilevel data information,which is then fed into downstream learning modules.Co-SFM employs an upstream fusion module to incorporate multilevel data,thereby constructing a macro-plate-micro data structure.This configuration helps identify and integrate characteristics from different data levels,facilitating a deeper understanding of the internal links within the financial system.In the downstream model,Co-SFM uses a state-frequency memory network to mine hidden frequency information within stock prices,and the multifrequency patterns of sequential data are modeled.Empirical results show that Co-SFM s prediction accuracy for stock price trends is significantly better than that of other models.This is especially evident in multistep medium and long-term trend predictions,where integrating multilevel data results in notably improved accuracy.

Harmonic Impedance Modeling and Oscillation Analysis of Modular Multilevel Converter

To facilitate rapid analysis of the oscillation stability mechanism in modular multilevel converter-based high voltage direct current(MMC-HVDC)systems and streamline the simulation process for determining MMC impedance characteristics,a simplified mathematical simulation model for MMC closed-loop impedance is developed using the harmonic state space method.This model considers various control strategies and includes both AC-side and DC-side impedance models.By applying a Nyquist criterion-based impedance analysis method,the stability mechanisms on the AC and DC sides of the MMC are examined.In addition,a data-driven oscillation stability analysis method is also proposed,leveraging a global sensitivity algorithm based on fast model results to identify key parameters influencing MMC oscillation stability.Based on sensitivity analysis results,a parameter adjustment strategy for oscillation suppression is proposed.The simulation results from the MATLAB/Simulinkbased MMC model validate the effectiveness of the proposed method.

模块化多电平矩阵换流器的等值阻抗模型解析分析

模块化多电平矩阵换流器(M3C)的阻抗建模是柔性低频输电系统稳定性分析和故障特性分析的关键理论基础。介绍了M3C的拓扑结构、数学模型与控制策略。在此基础上,分析了计及M3C拓扑结构特点、dq坐标变换过程和双dq分解控制的扰动电流-桥臂电压-扰动电压传递响应特性,推导了M3C等值阻抗特性与频率的关系,建立了可用固定电阻与随频率变化电抗串联表示的M3C等值阻抗数学模型。在PSCAD/EMTDC仿真平台上利用扫频法对等值阻抗理论分析的准确性进行验证,并讨论了系统控制参数、运行功率、一次参数等不同因素对M3C阻抗频率特性的影响。

一种低电压应力的三电平PFC电路研究

三电平及多电平电路具有更小的直流侧电压脉动和降低电路损耗的优点,并且能使直流侧电流波形更接近正弦化,因此提出一种基于四开关三电平PFC电路。利用四个开关管进行组合,使其具有多向开关功能,不仅能将输出电压抬升至三电平,降低开关管电压应力,还能为电感充电提供回路。同时该电路在每个模态最多两个开关管开通并共用一个脉冲信号,一定意义上简化了控制复杂度。最后,通过搭建一个额定功率为800 W的实验平台,验证理论分析正确性。

中性点不接地柔直配电网的单极接地故障暂态过程分析及保护新方案

针对中性点不接地的柔直配电网分析了直流馈线发生单极接地故障的暂态过程,提出了单极接地保护新方案,能有效解决现有直流线路保护不能反应中性点不接地柔直配电网的单极接地故障问题。在单极接地故障的分析中,将故障发展过程分为子模块电容放电阶段和交流重新馈入充电阶段。基于叠加原理分析了子模块电容放电阶段的电流流通路径、直流馈线暂态零模电流的电流成分和变化规律,得到故障馈线暂态零模电流主要呈现衰减非周期分量特征、非故障馈线暂态零模电流主要呈现振荡衰减分量特征的结论;利用牛顿迭代法推导了交流重新馈入充电的时刻,分析了影响因素并计算了过渡过程持续的最短时间。基于子模块电容放电开始时刻至交流重新馈入充电时刻这一段的暂态特征提出单极接地保护方案。该方案利用直流母线出现的零模电压启动保护,利用零模电压极性实现故障选极,利用故障馈线暂态零模电流绝对值的第一个积分时段值大于非故障馈线的值、且呈现衰减非周期分量特征选出故障馈线。搭建仿真模型,对故障分析结果和保护方案的有效性进行了验证。

基于Multilevel CodingTree模型的公路数字化档案标识编码研究

针对高速公路信息化建设中的编码问题,文章提出了基于Multilevel Coding Tree模型的"项目代号+属性+类别+流水号"四段位编码方案。根据该编码的结构,采用概率分析、实验测试和命题证明等手段,验证了编码的唯一性。该编码方案为公路信息化建设中各类文件提供了唯一的编码,达到一页(件)一码,是一种行之有效的编码方案。

Defect image segmentation using multilevel thresholding based on firefly algorithm with opposition-learning

To segment defects from the quad flat non-lead QFN package surface a multilevel Otsu thresholding method based on the firefly algorithm with opposition-learning is proposed. First the Otsu thresholding algorithm is expanded to a multilevel Otsu thresholding algorithm. Secondly a firefly algorithm with opposition-learning OFA is proposed.In the OFA opposite fireflies are generated to increase the diversity of the fireflies and improve the global search ability. Thirdly the OFA is applied to searching multilevel thresholds for image segmentation. Finally the proposed method is implemented to segment the QFN images with defects and the results are compared with three methods i.e. the exhaustive search method the multilevel Otsu thresholding method based on particle swarm optimization and the multilevel Otsu thresholding method based on the firefly algorithm. Experimental results show that the proposed method can segment QFN surface defects images more efficiently and at a greater speed than that of the other three methods.

AUTOMATIC MULTILEVEL THRESHOLDING METHOD BASED ON MAXIMUM ENTROPY

In the multilevel thresholding segmentation of the image, the classification number is always given by the supervisor. To solve this problem, a fast multilevel thresholding algorithm considering both the threshold value and the classification number is proposed based on the maximum entropy, and the self-adaptive criterion of the classification number is given. The algorithm can obtain thresholds and automatically decide the classification number. Experimental results show that the algorithm is effective.

基于多级编码调制的星座几何成形和重传技术

未来6G通信系统需要达到更高的峰值速率和频谱效率。由于在低密度奇偶校验码的解码算法上很难实现重大突破,相比于5G通信网络若要实现1~2个数量级的吞吐量提升,物理层比特交织编码调制系统的解调和解码的高效硬件实现是亟待解决的问题。多级编码调制是一种能够降低解调和解码实现复杂度的有效方案,其中部分调制比特可以采用分层解调,并只用经典低复杂度的代数码译码或者不进行译码。提出了一种基于高频谱效率多级编码调制的高阶星座几何成形和重传技术。为了优化几何成形的星座点,提出一种基于自编码结构的深度学习方法,通过并联编码器和串联解码器组成的自编码器,学习多级编码调制特性,并优化几何成形。相比于常规方形星座,自编码几何成形星座有约0.2 dB性能增益,同时只需原编码调制方案不到50%的编码长度,有效降低了解码硬件实现复杂度。还研究了基于Chase合并的重传方案,在重传时使用比特旋转的自编码几何成形星座图,能够有效提高传输性能。

适用于超大规模海上风电并网的直流送出系统

随着海上风电的超大规模开发,亟须提高输电廊道的利用率,实现超大规模海上风电并网的经济性和高效性。提出了适用于超大规模海上风电并网的直流送出系统构建方案,介绍了该系统的网架结构和电压等级、主接线方式、换流器拓扑以及陆上汇集站结构。在此基础上,提出了适用于该系统的交直流故障处理策略,包括系统平波电抗器配置、直流耗能装置配置和交直流故障处理策略。在PSCAD/EMTDC时域仿真软件中搭建了±500 kV/10000 MW海上风电直流送出系统的仿真模型,对交直流故障进行仿真,验证了所提方案及其交直流故障处理策略的可行性。

Risk Assessment of Diary Cattle Brucellosis Based on Systematic Multilevel Grey Relation Entropy Method

[Objective] The study was to explore the major factors affecting diary cattle brucellosis risk assessment,as well as their strong-to-weak sequence,so as to provide theoretical basis for assessing diary cattle brucellosis risk level in different regions.[Method] From 4 dimensions of feeding and importing,breeding,housing and polyculture situation,an evaluation index system was set up,and diary cattle brucellosis risk survey was conducted in 3 typical regions.Finally,systematic multilevel grey relation entropy method was applied to perform data analysis.[Result] The strong-to-weak sequence of Level 1 impact factor of diary cattle brucellosis was as follows：feeding and importinghousingpolyculture situationbreeding;the sequence of Level 2 impact factor was U32〉U12〉U11〉U31〉U21〉U42〉U43〉U23〉U22〉U41;the risk level sequence of 3 typical regions was Province A（County A1,A2,A3）Province B（County B1,B2,B3）Province C（County C1,C2,C3）.[Conclusion] According to the weight of Level 1 index strata,administrative departments at all levels and dairy cattle farmers should lay emphasis on the aspects of feeding,importing and housing;viewed from the perspective of Level 2 index strata,dairy cattle farmers should value the siting of cattle field,the brucellosis surveillance before importing and milking modes most.According to the diary cattle brucellosis risk level of 3 typical regions,if administrative departments at all levels strengthen peoples＇ awareness of their personal health and increase investment in this area,with new healthy cultured atmosphere built,the risk level of diary cattle brucellosis will surly decline.

改进的量子安全直传Ping-Pong协议

为了提高Ping-Pong协议的传输效率,对其加以改进。改进的协议增加了随机数序列。相对于原协议,将传输的经典消息与控制信息从1∶1的比例改变为N∶(M-N)。按照量子通信效率评价公式,相对于原协议0.333的通信效率,改进协议的Matlab仿真和数值推导结果均显示,只需满足条件N<M<2 N,其效率即可提高至N/(2 M-N);在最少控制模式的情况下,只要N>1,极限通信效率可达N/(N+2),故改进后的效率均大于原协议。

基于道路载荷的副车架台架试验载荷谱编制研究

某轻型商用车在整车道路耐久测试中出现副车架开裂失效问题,针对该问题,采集控制臂球销处的道路载荷谱,按虚拟S-N曲线计算球销载荷谱的伪损伤,根据Miner线性疲劳损伤累积原则,计算得到球销处的全寿命损伤。选取合适的多级载荷幅值,并根据损伤等效原则,得到各级载荷幅值的循环次数。按照损伤等效计算得到的多级载荷谱对副车架和控制臂进行台架试验,台架试验结果复现了副车架的路试开裂问题,且失效台架失效模式、寿命与整车路试结果有很好的关联性。后续优化后的副车架用该多级载荷谱进行台架验证通过后同样通过了路试耐久考核。

Design of Serially Concatenated Two-Level Polar Coded Modulation System with Low-Complexity

Multilevel coding(MLC)is a commonly used polar coded modulation scheme,but challenging to implement in engineering due to its high complexity and long decoding delay for high-order modulations.To address these limitations,a novel two-level serially concatenated MLC scheme,in which the bitlevels with similar reliability are bundled and transmitted together,is proposed.The proposed scheme hierarchically protects the two bit-level sets:the bitlevel sets at the higher level are sufficiently reliable and do not require excessive resources for protection,whereas only the bit-level sets at the lower level are encoded by polar codes.The proposed scheme has the advantages of low power consumption,low delay and high reliability.Moreover,an optimized constellation signal labeling rule that can enhance the performance is proposed.Finally,the superiority of the proposed scheme is validated through the theoretical analysis and simulation results.Compared with the bit interleaving coding modulation(BICM)scheme,under 256-quadrature amplitude modulation(QAM),the proposed scheme attains a performance gain of 1.0 dB while reducing the decoding complexity by 54.55%.

“五基”协同生物多样性监测技术体系构建研究

生物多样性保护是当今国际社会最为关注的热点之一,而生物多样性监测作为其重要基础,是确保有效保护措施得以实施的前提。传统的生物多样性监测主要基于实地调查,这不仅费时费力成本高,常常难以覆盖广泛的区域和满足长期监测的需求。在此背景下,遥感技术因其具备省时省力、长时序、高精度、多尺度动态监测等优势,为生物多样性监测提供了有利的工具,但目前缺乏联合多平台观测的生物多样性指标体系。为此,本研究提出了一种“五基”协同生物多样性监测的概念,具体包括天基卫星、空基遥感、航空无人机、移动巡护监测车和地面观测。此外,在深入分析“五基”协同生物多样性监测体系必要性的基础上,提出“五基”协同生物多样性监测技术体系,包括“五基”协同生物多样性监测指标体系,以及“五基”协同生物多样性监测技术体系亟需解决的网络布局、数据融合和预警平台建设等关键技术。“五基”协同生物多样性监测技术体系的构建不仅能使各监测平台和各类技术优势互补,还能促进构建形成全方位、立体化的生物多样性监测网络,以期有效提升我国生物多样性监测水平,为全球生物多样性保护做出积极贡献。

基于多元化多层次教学的高校工科课程思政探索与融入

课程思政与专业课程教学的融合是高校承担立德树人根本任务的重要体现。大气污染控制工程是高校环境科学与工程类专业的核心专业课,该文抓住高校工科课程大气污染控制工程的基础核心能力培养的课程地位,通过以学生为中心、以培养一流人才为导向和持续改进的工程教育理念来构建课程的主线和思政元素的探索融入,即通过线上线下混合式教学-翻转课堂-课程实验-课程设计-校外专家讲座的多元化教学模式探索课程思政元素,并将思政元素融入知识—能力—实践—思维—素养逐层递进的多层次教学过程。通过专业核心课程思政元素的探索与融入,培养具有新时代生态文明建设理念,能解决复杂大气问题的高级工程技术人才。

基于直流电流反馈的MMC-HVDC系统的中高频振荡抑制策略

基于模块化多电平换流器的柔性直流输电(modular multilevel convertor based high voltage direct current,MMC-HVDC)系统存在的中高频振荡问题严重危胁电力系统的正常运行。首先,基于MMC的动态相量模型,建立了MMC的交流侧阻抗模型;其次,利用阻抗法分析控制环节及控制参数对MMC阻抗特性的影响,得到了功率外环、电流内环及控制链路延时是导致MMC呈现负阻尼特性的主要原因;再次,在分析现有基于电压前馈环节和电流内环的协同振荡抑制策略不足的基础上,提出了功率外环附加直流电流反馈的振荡抑制策略,极大程度消除系统中的谐波分量,改善了MMC的阻抗特性;最后,通过电磁仿真软件验证理论分析和抑制措施的正确性与有效性。