Comparison between Equivalent Charge Model and Equivalent Dipole Model on Realistic Head Model

Equivalent source layer （ESL） imaging is an important kind of high-resolution electro- encephalogram （EEG） imaging. It consists of two categories： equivalent dipole layer （EDL） and equivalent charge layer （ECL）. Both of them are assumed to be located on or near the cortical surface and have been proposed as high-resolution imaging modalities or as intermediate steps to estimate the epicortical potential. Here, EDL and ECL based on a realistic head model are presented, both simulations and real data experiment are done to compare these two models. The results show that ECL can provide higher spatial resolution about source location than EDL does.

Effect of head model on Monte Carlo modeling of spatial sensitivity distribution for functional near-infrared spectroscopy

Modeling Light propagation within human head to deduce spatial sensitivity distribution(SSD)is important for Near-infrared spectroscopy(NIRS)/imaging(NIRI)and diffuse correlation tomography.Lots of head models have been used on this issue,including layered head model,artificial simplified head model,MRI slices described head model,and visible human head model.Hereinto,visible Chinese human(VCH)head model is considered to be a most faithful presentation of anatomical structure,and has been highlighted to be employed in modeling light propagation.However,it is not practical for all researchers to use VCH head models and actually increasing number of people are using magnet resonance imaging(MRI)head models.Here,all the above head models were simulated and compared,and we focused on the effect of using di®erent head models on predictions of SSD.Our results were in line with the previous reports on the effect of cerebral cortex folding geometry.Moreover,the in fluence on SSD increases with thefidelity of head models.And surprisingly,the SSD percentages in scalp and gray matter(region of interest)in MRI head model were found to be 80%and 125%higher than in VCH head model.MRI head models induced nonignorable discrepancy in SSD estimation when compared with VCH head model.This study,as we believe,is the first to focus on comparison among full serials of head model on estimating SSD,and provided quantitative evidence for MRI head model users to calibrate their SSD estimation.

Interictal Electrophysiological Source Imaging Based on Realistic Epilepsy Head Model in Presurgical Evaluation:A Prospective Study

Invasive techniques are becoming increasingly important in the presurgical evaluation of epilepsy.Adopting the electrophysiological source imaging(ESI)of interictal scalp electroencephalography(EEG)to localize the epileptogenic zone remains a challenge.The accuracy of the preoperative localization of the epileptogenic zone is key to curing epilepsy.The T1 MRI and the boundary element method were used to build the realistic head model.To solve the inverse problem,the distributed inverse solution and equivalent current dipole(ECD)methods were employed to locate the epileptogenic zone.Furthermore,a combination of inverse solution algorithms and Granger causality connectivity measures was evaluated.The ECD method exhibited excellent focalization in lateralization and localization,achieving a coincidence rate of 99.02%(p<0.05)with the stereo electroencephalogram.The combination of ECD and the directed transfer function led to excellent matching between the information flow obtained from intracranial and scalp EEG recordings.The ECD inverse solution method showed the highest performance and could extract the discharge information at the cortex level from noninvasive low-density EEG data.Thus,the accurate preoperative localization of the epileptogenic zone could reduce the number of intracranial electrode implantations required.

Computer model of the human head-neck and finite element analysis

The difficulty in establishing the finite element model of head and cervical spine is interpreted in the study. A head-neck 3D model is constructed accurately and quickly by the technology of CT scan,the automatically modeling of Mimics software and the RE technology of Geomagic software. Then the finite element model of the head-neck which is close to the real one is set up by the preprocessor of the FEM soft ware ANSYS. After the transient finite element analysis is performed on the model,the historical response of the displacement of the head is obtained. The result is validated by the result of the existed experiment. The stress,as well as the deformation,of nodes in the head and the cervical spine at any time benefits a lot to the clinic study on the injure to the head and neck caused by the impacts. And all the analysis is done by limited computer available.

Modeling and simulation of crushing process of spiral mining head

According to the characteristics of spiral mining head for deep seabed cobalt-rich crust, the kinematic model, cutting loads model, quantity of cutting picks model of mining head, granularity distribution model and energy consumption model were constructed. Based on these models, computer simulation program of cutting loads was developed with VB software. The mechanical parameters of mining head were obtained in the cutting depth range of 5160 mm. Making use of the simulation results, the effect of cutting depth of spiral mining head on the mining process was studied. The results show that the maximum force of single pick is 4.7051kN, the maximum force and torque of spiral drum of mining head are respectively 34.1668kN and 3.8795kN·m at the cutting depth of 160mm.

A Rabbit Model of Hormone-induced Early Avascular Necrosis of the Femoral Head

Objective To establish an experimental model of early stage avascular necrosis of the femoral head （ANFH） caused by corticosteroid in adult rabbits and to observe the pathological changes with various imaging techniques. Methods ANFH was induced by a combination of hypersensitivity vasculitis caused by injection of horse serum and subsequent administration of a high dose of corticosteroid. The pathological changes were detected with digital radiography （DR）, computed tomography （CT）, magnetic resonance imaging （MRI）, ink artery infusion angiography, hematoxylin-eosin staining, and immunohistochemistry. Results The imageological and pathological changes corresponded to the clinical characteristics of early stage ANFH. DR showed bilaterally increased bone density, an unclear epiphyseal line, and blurred texture of cancellous bone. CT showed spot-like low-density imaging of cancellous bone, thinner cortical bone, osteoporosis, and an unclear epiphyseal line. MR! showed bone marrow edema and spot-like high signals in T2-weighted imaging in cancellous bone. Ink artery infusion angiography showed fewer obstructed blood vessels in the femoral head. HE staining of pathological sections showed fewer trabeculae and thin bone, an increased proportion of empty osteocyte lacunae, decreased hematopoiesis, thrombosis, and fat cell hypertrophy. Immunohistochemistry showed attenuated expression of vascular endothelial growth factor in osteoblasts and chondrocytes, and on the inner membrane of blood vessels. Conclusion Experimental rabbit model of early stage ANFH caused by corticosteroid can be successfully established and provide the foundation for developing effective methods to treat early stage ANFH.

Extraction and Analysis of Gully Head of Loess Plateau in China Based on Digital Elevation Model

In China′s Loess Plateau area, gully head is the most active zone of a drainage system in gully areas. The differentiation of loess gully head follows geospatial patterns and reflects the process of the loess landform development and evolution of its drainage system to some extent. In this study, the geomorphic meaning, basic characteristics, morphological structure and the basic types of loess gully heads were systematically analysed. Then, the loess gully head′s conceptual model was established, and an extraction method based on Digital Elevation Model(DEM) for loess gully head features and elements was proposed. Through analysing the achieved statistics of loess gully head features, loess gully heads have apparently similar and different characteristics depending on the different loess landforms where they are found. The loess head characteristics reflect their growth period and evolution tendency to a certain degree, and they indirectly represent evolutionary mechanisms. In addition, the loess gully developmental stages and the evolutionary processes can be deduced by using loess gully head characteristics. This study is of great significance for development and improvement of the theoretical system for describing loess gully landforms.

Thrust and Torque Characteristics Based on a New cutter-head Load Model

Full face rock tunnel boring machine（TBM） has been widely used in hard rock tunnels, however, there are few published theory about cutter-head design, and the design criteria of cutter-head under complex geological is not clear yet. To deal with the complex relationship among geological parameters, cutter parameters, and operating parameters during tunneling processes, a cutter-head load model is established by using CSM（Colorado school of mines） prediction model. Force distribution on cutter-head under a certain geology is calculated with the new established load model, and result shows that inner cutters bear more force than outer cutters, combining with disc cutters abrasion; a general principle of disc cutters＇ layout design is proposed. Within the model, the relationship among rock uniaxial compressive strength（UCS）, penetration and thrust on cutter-head are analyzed, and the results shows that with increasing penetration, cutter thrust increases, but the growth rate slows and higher penetration makes lower special energy（SE）. Finally, a fitting mathematical model of ZT（ratio of cutter-head torque and thrust） and penetration is established, and verified by TB880 E, which can be used to direct how to set thrust and torque on cutter-head. When penetration is small, the cutter-head thrust is the main limiting factor in tunneling; when the penetration is large, cutter-head torque is the major limiting factor in tunneling. Based on the new cutter-head load model, thrust and torque characteristics of TBM further are researched and a new way for cutter-head layout design and TBM tunneling operations is proposed.

Radiotherapy-customized head immobilization masks:from modeling and analysis to 3D printing

Immobilization devices may be a valuable aid to ensure the improved effectiveness of radiotherapy treatments where constraining the movements of specific anatomical segments is crucial. This need is also present in other situations, specifically when the superposition of various medical images is required for fine identification and characterization of some pathologies. Because of their structural characteristics, existing head immobilization systems may be claustrophobic and very uncomfortable for patients, during both the modeling and usage stages. Because of this, it is important to minimize all the discomforts related to the mask to alleviate patients’ distress and to simultaneously guarantee and maximize the restraint effectiveness of the mask. In the present work, various head immobilization mask models are proposed based on geometrical information extracted from computerized tomography images and from 3D laser scanning point clouds. These models also consider the corresponding connection to a radiotherapy table, as this connection is easily altered to accommodate various manufacturers’ solutions. A set of materials used in the radiotherapy field is considered to allow the assessment of the stiffness and strength of the masks when submitted to typical loadings.

基于PPR和NSGA-Ⅱ的泵前微压过滤器水力与过滤性能研究

【目的】探究泵前微压过滤器的性能。【方法】开展5组流量(2~8m^(3)/h)、5组含沙量(0.5~2.0g/L)、3组滤网过滤面积(1 105、1 582、2 060 cm^(2))和4组分水器型式(不加、1型、2型、3型)的物理模型试验,采用投影寻踪回归分析法(PPR)、多目标遗传算法(NSGA-Ⅱ),建立水头损失、截沙质量和总过滤效率的预测模型,探究各指标的影响因素排序,确定泵前微压过滤器的最佳运行工况。【结果】影响泵前微压过滤器水头损失的因素排序为进水流量?含沙量?滤网过滤面积;影响截沙质量的因素排序为含沙量?滤网过滤面积?进水流量;影响总过滤效率的因素排序为滤网过滤面积?含沙量?进水流量;以相对误差≤10%作为判定标准,建立的截沙质量和总过滤效率PPR预测模型合格率为100%,模型精度较高,但水头损失PPR预测模型合格率仅为70%,模型不可靠。本试验范围下泵前微压过滤器的最佳运行工况为:含沙量2 g/L、进水流量7 m^(3)/h、滤网过滤面积2 060 cm^(2)。【结论】PPR预测模型对截沙质量和总过滤效率的预测精度较高,对水头损失的预测误差较大,在后期可用量纲分析与多元回归相结合预测水头损失、截沙质量和总过滤效率。

个性化头部生物力学模型的开发及验证

本文提出了一种个性化头部生物力学模型建模方法,并对所生成模型进行了有效性验证。该方法以图斯特50th百分位头部生物力学模型为基础,基于目标模型头部CT数据,采用三维点云配准和自由网格变形法,实现具有详实脑组织结构的个性化头部生物力学模型的快速建模。通过重构经典尸体试验,发现该方法构建的个性化头部生物力学模型在运动学和生物力学响应方面与尸体试验结果高度一致,且与通过逆向工程方法开发的头部生物力学模型并无明显差异,验证了本文方法所开发模型的有效性。因此,本文方法可用于快速构建具有详细解剖学结构的个性化头部生物力学模型,为损伤生物力学、临床医学和法医鉴定等领域的数字化需求提供基础计算分析工具。

有限元方法在脑震荡领域的热点:脑损伤模型、测试方法与防护装备的改进

背景:由身体接触性运动或交通事故造成的脑震荡远比人们想象的更为严重与常见,近年来引起了媒体、医学界及体育界的广泛关注与高度重视。目的:采用文献计量学方法对有限元方法在脑震荡领域的研究热点与趋势进行可视化分析,从而为中国在该领域的研究提供一定的参考。方法:基于Web of Science核心集数据库进行文献检索,检索主题词策略为(TS=(Concussion)) AND TS=(Finite element),利用CiteSpace 6.2.R4可视化工具对纳入文献的作者、国家、机构、关键词及被引文献等进行可视化分析。结果与结论:(1)共计纳入215篇文献,发文量与被引量总体上呈上升趋势;学科分布涉及生物医学工程、生物物理学、运动科学、临床神经学及神经科学等学科,呈现多学科交叉融合的趋势;发文量最多的作者是来自爱尔兰都柏林大学的Gilchrist M,发文量最多的机构是渥太华大学,发文量最多的国家是美国。(2)通过关键词分析发现研究的热点聚焦于脑损伤模型的建立用来模拟和预测脑震荡的损伤;脑震荡损伤机制的解析;防护设备和装置的优化设计。(3)通过文献共被引分析发现脑损伤的预测与评估是该领域的知识基础亦是研究热点。(4)有限元方法运用在脑震荡领域的研究热点主要围绕头部损伤预测为主题展开,结合探索大脑损伤机制以及防护装备的设计与改进。(5)随着人工智能与材料学的进步,未来有限元方法在脑震荡损伤领域的研究热点将集中于脑损伤模型、测试方法与防护装备的改进。

基于改进CSM模型的硬岩掘进机刀盘危险点应力分析方法

TBM刀盘受载后的危险点应力获取缺少直接的测量方法,工况复杂的情况下也难以测量,这就制约了刀盘载荷分析在刀盘寿命分析及其再制造方向上的应用问题,为此本文提出了一种基于改进CSM模型的TBM刀盘危险点应力分析方法.在CSM模型基本压力假设的基础上,提出了滚刀刀刃侧面基本压力的概念,推导计算了滚刀刀刃侧面受到的压力和摩擦力,并将二者逐个引入CSM模型中的三向力的计算,建立了改进的CSM模型;通过与公开的滚刀载荷实验数据对比,计算得到的三向力误差均在5%以内,弥补了CSM模型不能预测侧向力的不足.基于改进的CSM模型,通过分析滚刀载荷三向力的差值关系,建立了滚刀载荷差值与滚刀刀间距离的指数关系,得到了计算刀盘滚刀载荷的理论模型,使用ABAQUS的实体耦合功能,加载上各滚刀的载荷,分析整个刀盘的载荷分布,进一步获得刀盘危险点的位置.由此建立了一套刀盘滚刀群载荷获取及危险点应力分布计算的方法.通过与辽宁大伙房水库引水隧道工程中公开的实验数据及危险点统计数据对比,验证了基于改进CSM模型的TBM刀盘危险点应力计算方式的有效性.该研究对经典的CSM模型进行了改进,所提出的刀盘危险点的应力分析方法可为刀盘再制造寿命预测提供可靠的载荷分析依据,并指导刀盘服役阶段的操控参数设置.

口腔医学仿真头模实验室的科学化管理

口腔仿真头模实验训练系统是面向21世纪最符合口腔颌面部解剖、生理特点的口腔临床实验教学设备,是集口腔临床模拟训练、临床基本技能实践操作与实验信息化教学为一体的,是目前国内外较先进的口腔医学实验教学平台。从先期使用培训、基础条件的维护与更新、使用过程的跟踪管理等三个方面阐述了该实验室的系统化管理方案,科学化、精细化和规范化管理好仿真头模实验室,保证好教学质量。本着配合好理论授课的教学内容与目标、服务好每名口腔医学生的理念,总结了一套科学有效的系统化管理方法,建立了科学系统的管理制度,体现了口腔实验教学中心的管理水平,是推动口腔医学实验教学不断进步,培养业务能力强、素质高的现代化口腔医学临床创新人才的基础。

地下矿山非爆机械化智能采掘

非爆机械化采掘是替代传统钻爆法进行深部硬岩开挖的一种新方法,其智能化升级包括智能感知、智能决策和智能控制。在综合分析岩石采掘工程涉及的两大问题(破碎和稳定)和三大要素(环境条件、岩体特性、采掘参数)的基础上,建立包括岩体及环境特性原位监测、硬岩可切割性改善、采掘参数智能控制和采掘表现性能评价在内的非爆机械化智能采掘工艺,以实现岩石采掘装备的机械化、自动化、无人化,采掘工艺的连续化、精细化、协同化,以及采掘管理的信息化、数字化、智能化。此外,建立非爆机械化智能采掘PDCA循环管理模式,通过深部高应力诱导利用和能量调控、硬岩诱变改性降危增割和多源载荷联合破岩3个子循环的协同,实现地下矿山安全高效采掘。

逆向工程技术在石膏头像设计中的应用

借助专用逆向软件,采用逆向技术对石膏头像的点云扫描数据进行预处理和数模重构,从而完成了其逆向建模设计。将扫描数据导入Geomagic Wrap软件中,进行清除噪点、全局注册、合并、补孔、平滑等预处理;预处理后的数据以STL格式导入Geomagic Design X软件中进行进一步的数模重构。对重构后的模型进行了偏差分析,结果表明逆向重构精度符合设计要求。

动水头作用下花岗岩风化土的内部侵蚀机理

[目的]揭示动水头作用下花岗岩风化土侵蚀演化的动态过程,研究动态水力条件对土体内部侵蚀发展的影响,探明颗粒迁移规律与内部侵蚀机理,为深入研究花岗岩边坡的破坏模式与促滑机理提供理论依据。[方法]设计竖向土柱渗流装置,开展上升水头与正弦水头条件下花岗岩风化土柱的渗流试验,基于渗流土柱顶面与侧面的试验现象,从渗流速度变化、颗粒流失量变化和渗流前后颗粒级配、质量变化等方面,分析动水头作用下花岗岩风化土内部侵蚀的发育特征。[结果]①花岗岩风化土粒径差异较大,在骨架间存在微小孔隙,渗流冲刷作用使得土颗粒通过土体骨架间的孔隙运移流失。在内部侵蚀过程中,细颗粒流失量相对较多,粗颗粒流失量较少。②土体内部侵蚀作用是渐进发展的过程,在土体薄弱区域的结构最先产生变形与破坏。试验中渗流泉眼由土柱边界开始发展到土柱中部区域,渗流通道沿着渗流方向自下而上发育,水力条件短时间内发生显著变化会造成渗流通道快速贯通。③土体内部侵蚀作用将随渗流时间推进而趋于稳定,但正弦水头将“激活”土颗粒运动,加剧土体的内部侵蚀作用。加大水头变化幅度或减小水头变化周期,能够加剧土体内部侵蚀作用,导致水流运移速度加快以及颗粒迁移流失量增多。[结论]水力条件变化对土体内部侵蚀作用存在显著影响,正弦水头更能加剧颗粒迁移流失。

基于精神情感状况导向的照护模式在重症颅脑损伤术后恢复期患者中的应用

目的 探讨基于精神情感状况导向的照护模式在重症颅脑损伤术后恢复期患者中的应用效果。方法 选取2020年2月至2023年2月湖南中医药高等专科学校附属第一医院100例重症颅脑损伤恢复期患者,以奇偶数法分为对照组和干预组,各50例。对照组于术后恢复期给予常规护理干预,干预组在对照组的基础上给予基于精神情感状况导向的照护模式干预,干预1个月。比较两组干预前后负面情绪[焦虑自评量表(SAS)及抑郁自评量表(SDS)]、日常生活活动能力[改良Barthel指数(MBI)]及认知功能[蒙特利尔认知评估量表(Mo CA)]。结果 干预后,两组SAS、SDS评分低于干预前,且干预组低于对照组(P<0.05);两组MBI、Mo CA评分高于干预前,且干预组高于对照组(P<0.05)。结论 基于精神情感状况导向的照护模式可改善重症颅脑损伤术后恢复期患者的负面情绪,提高日常生活活动能力和认知功能。

隔膜式电磁阀内部流场数值模型构建与流动特性分析

基于k-ε(k为湍流动能,ε为湍流耗散率)湍流模型,以进口质量流量、出口静压为数值计算条件,建立了隔膜阀内部流场的数值模拟模型,并对模型的精度进行了试验验证。在此基础上,应用该模型分析了不同进口流量(2.787~33.273 kg/s)条件下阀体内部流动特性及压力场分布规律,并建立了进口流量与阀体水头损失的精确数量关系。结果表明:(1)数值模拟能较好的预测不同流量条件下阀体的水头损失,在进口流量分别为5.546、11.091和16.637 kg/s时,试验与数值模拟相对误差仅为-6.433%、4.619%和7.264%。(2)在进口流量恒定的条件下,从进口至出口,流道内的静压总体沿程呈减小趋势,在阀体内部由于阀坎的阻挡造成流道收缩以及水流撞击隔膜产生折流而出现较大的静压变化梯度。(3)水流在经过阀坎上的窄流道后,在阀体下游形成明显的空化区,伴随着有一定的回流现象,阀体下游的空化区主要出现在距出口1/3流体域处,随着进口流量的增大,阀体下游的涡流更加剧烈,回流现象更为显著,但回流区的范围并未显著增加。(4)在模型精度验证的基础上,应用该模型进一步分析了18种进口流量条件下阀体内部流动特性及压力场分布规律,并建立了进口质量流量Q与阀体水头损失?P的数量关系,当进口质量流量Q从2.787~15.428 kg/s,雷诺数从37927~215984时的拟合方程为?P=2076.31Q-7567.49,R^(2)=0.964;进口质量流量从17.141~33.273 kg/s,雷诺数从240097~467009时的拟合方程为?P=5688.02Q-67317.39,R^(2)=0.993,为灌溉管网水力计算提供了参考依据。

改进YOLOv5n的管道DR缺陷图像检测方法

近年来,数字射线成像技术(digital radiography,DR)由于其独有优势已被广泛应用于工业管道无损检测。为提高管道DR缺陷图像检测精度,提出了一种改进的YOLOv5n管道DR缺陷图像检测方法。该方法有两点贡献,针对目标检测网络中分类和回归两个任务存在冲突的问题,设计了任务独立解耦检测头,通过分别为两类任务构建独立的特征图实现解耦。为了缓解解耦检测头模块带来的参数量增加问题,引入了轻量化的深度可分离卷积替代标准卷积,在保证精度的同时,减少模型参数量。实验结果表明,在管道缺陷数据集上,该方法的mAP@0.5比YOLOv5n提高0.9个百分点。与YOLOv4、Faster-RCNN和SSD等其他几种目标检测模型的对比实验表明,该方法在mAP@0.5、参数量和计算量上都达到最优,有效提高了管道DR缺陷图像检测的性能。