虚拟手术仿真中人体软组织形变技术的研究

对虚拟手术仿真中人体软组织形变技术进行深入研究,利用OpenGL三维图形标准建立了基于质点-弹簧物理模型的虚拟人体软组织形变系统。围绕虚拟手术仿真中人体软组织形变的逼真度和实时性两大要素展开研究,通过对比四边形网格结构提出了改进的基于质点-弹簧模型的正六边形几何拓扑结构,并对软组织形变动力学模型及其数值积分算法、软组织形变力反馈计算模型进行了讨论,针对以往的虚拟手术器械与软组织表面接触时作用点的最近邻质点求取算法存在的不足,提出了改进的求取算法。实验结果表明,改进的算法在模拟软组织形变时具有较好的稳定性和实时性。     

机械产品造型及外观评价体系研究

随着社会的发展,机械产品受到越来越多人的关注,对其进行外观设计及评价研究可有效提高产品的附加值,推动产品的不断进化。本文主要论述了机械产品的设计要素及相关设计评价,对于机械产品的造型设计具有重要的借鉴意义。     

Marine-Derived Hydrogels for Biomedical Applications

Marine organisms provide novel and broad sources for the preparations and applications of biomaterials. Since the urgent requirement of bio-hydrogels to mimic tissue extracellular matrix (ECM), the natural biomacromolecule hydrogels derived from marine sources have received increasing attention. Benefiting from their outstanding bioactivity and biocompatibility, many attempts have been made to reconstruct ECM components by applying marine-derived natural hydrogels. Moreover, marine hydrogels have been successfully applied in biomedicine by means of microfluidics, electrospray, and bioprinting. In this review, the classification and characteristics of marine-derived hydrogels are summarized. In particular, their role in the development of biomaterials is also introduced. Then, the recent advances in bio-fabrication strategies for various hydrogel materials are focused upon. Besides, the influences of hydrogel types on their functions in biomedical applications are discussed in depth. Finally, critical reflections on the limitations and future development of marine-derived hydrogels are presented.     

Multiphoton Lithography as a Promising Tool for Biomedical Applications

Multiphoton lithography (MPL) is a powerful and useful structuring tool capable of generating 2D and 3D arbitrary micro- and nanometer features of various materials with high spatial resolution down to nm-scale. This technology has received tremendous interest in tissue engineering and medical device manufacturing, due to its ability to print sophisticated structures, which is difficult to achieve through traditional printing methods. Thorough consideration of two-photon photoinitiators (PIs) and photoreactive biomaterials is key to the fabrication of such complex 3D micro- and nanostructures. In the current review, different types of two-photon PIs are discussed for their use in biomedical applications. Next, an overview of biomaterials (both natural and synthetic polymers) along with their crosslinking mechanisms is provided. Finally, biomedical applications exploiting MPL are presented, including photocleaving and photopatterning strategies, biomedical devices, tissue engineering, organoids, organ-on-chip, and photodynamic therapy. This review offers a helicopter view on the use of MPL technology in the biomedical field and defines the necessary considerations toward selection or design of PIs and photoreactive biomaterials to serve a multitude of biomedical applications.     

Three Potential Elements of Developing Nerve Guidance Conduit for Peripheral Nerve Regeneration

Autograft replaced by a nerve guidance conduit (NGC) is challenging in peripheral nerve injury because current NGC is still limited by precise conductivity and excellent biocompatibility in vivo, which influences the peripheral nerve repair even for a long lesion gap repair. Several particular elements have the potential function for nerve conductivity acceleration based on the traditional three factors of neural tissue engineering. The review aims to address three questions: 1) What is the superior factor for nerve conduction in the application? 2) How can a more conductive regenerative scaffold be constructed in vivo? 3) What is the next step in nerve regeneration for NGC? The bibliometrics analysis of NGC-related references is adopted to acquire that the conductive material, manufacturing technology of neural scaffold, and electrical stimulation (ES) play essential roles in the acceleration of nerve conduction. This review visually analyses the research status and summarizes the main types of conductive materials, the manufacturing technologies of neural scaffolds, and the characteristics of ES. The viewpoints and outlook of developing NGC are also discussed in this review. The proposed three elements are expected to improve the nerve conduction of NGC in vivo and even address the dilemma of long-distance peripheral nerve injury.     

含高比例风光接入的输电网氢-电混合储能系统配置方法

目前高比例风光接入的输电网存在弃风弃光率普遍较高的问题,配置储能设备作为一种具有潜在效用的手段在当前的研究中备受青睐。针对输电网储能配置问题,为达到综合成本减小和弃风弃光率降低的目的,提出了一种基于双层规划模型的输电网氢-电混合储能系统配置方法。首先,对氢-电混合储能系统的特性进行建模,在此基础上建立输电网氢-电混合储能系统功率与容量配置双层规划模型。上层模型以配置储能后年综合成本最小为目标;下层模型以弃风弃光率最小为目标。其后基于蓄电池和氢储能的不同特性,提出一种氢-电混合储能系统配合策略。最后,针对该模型非线性多目标的特点,采用双层迭代粒子群算法与潮流计算相结合进行模型求解。在算例仿真部分,以某含有高比例风光接入地区输电网为例,进行氢-电混合储能系统容量和选址的优化配置,验证了所建模型和所提求解算法的可行性和有效性。提高了风电光伏出力在时序上的转移能力,减少了高碳化石能源的消耗量,降低了弃风弃光率。     

新能源同步机与调相机在高比例新能源电网中应用的比较

针对高比例新能源电网的电压稳定问题和新能源脱网风险,新能源同步机(Motor Generator Pair,MGP)系统和调相机均能发挥重要作用。为对比二者的动态特性,本文介绍了MGP结构和控制策略,分析了MGP的无功调节原理和机械隔离作用。推导了调相机的动态调节特性及无功调节能力的影响参数。在PSCAD中分别搭建了MGP和调相机接入新能源并网系统的仿真模型,对比了不同故障情况下MGP和参数优化前、后调相机的动态特性,结果表明MGP和调相机都具备抑制电压跌落的能力,而MGP的机械隔离作用可以隔离故障对逆变器和新能源机组的大部分影响,防止新能源大量脱网。     

土石坝掺砾心墙料的击实特性研究北大核心CSCD

心墙土料的击实特性能够反映实际工程建设时的压实效果。本文选择一种风积土料和花岗岩砾石料,开展不同含水率、不同掺砾比例及不同击实功等条件下的击实特性试验研究,探索掺砾土料击实干密度与含水率、掺砾比例及击实功之间的关系。试验结果表明:随着含水率的增加,掺砾土料的击实曲线呈先增后减的抛物线型关系;随掺砾含量增大,重型击实功条件下掺砾土料的击实干密度呈现先增后减的变化规律;随掺砾含量增大,轻型击实功条件下掺砾土料的击实干密度近似成比例线性增加;对相同掺砾比例的掺砾土料,随击实功能的增大,其击实干密度逐渐增大,并最终趋于收敛。     

基于频率安全约束与临界惯量计算的分时段限制风电出力方法

高比例风电接入导致系统等效惯量降低,增加了电网引发频率失稳的可能性。为保障日内频率安全稳定运行,同时避免大面积切除风电的不合理操作,提出了基于频率安全约束与临界惯量计算的分时段限制风电出力方法。通过引入频率最低点和最大频率变化率约束指标,并考虑日内运行方式变化,分时段求解电网临界惯量及对应的最大风电并网容量。结合电网实际惯量判定小于临界惯量的时段,对这些时段依据最大风电并网容量确定风电切除量,从而在日内各时段消除频率安全隐患。最后通过算例系统证明：所提方法能准确筛查电网日内存在频率安全风险的时段,求解的风功率分时段切除量可有效消除频率安全隐患。     

面向网络节点的新能源高占比系统消纳阻力精细化评估

随着新能源装机容量的不断提升,新能源高占比系统弃风弃光问题严峻,开展新能源消纳问题研究,精确定位新能源消纳阻力对提升新能源消纳措施的制定有重要意义。文中提出一种面向网络节点的电力系统新能源消纳阻力精细化评估方法。首先,基于潮流追踪算法将网络节点潮流划分为常规机组注入、新能源注入和负荷流出三部分;其次,从网络节点角度建立调峰、调频及节点电压偏差约束与新能源消纳的数学关系模型,计及三者耦合关系分析网络节点弃电情况;然后,构建基于网络节点的新能源消纳阻力评估模型并求解,定位系统中新能源消纳的关键节点,明确各节点新能源消纳制约因素并量化新能源消纳阻力;最后,基于改进IEEE 39节点系统设计算例,验证了评估方法的有效性。所提评估方法可为电力部门采取措施以提升新能源消纳提供依据。