Adaptive energy-preserving algorithms for guiding center system

We develop two types of adaptive energy preserving algorithms based on the averaged vector field for the guiding center dynamics,which plays a key role in magnetized plasmas.The adaptive scheme is applied to the Gauss Legendre’s quadrature rules and time stepsize respectively to overcome the energy drift problem in traditional energy-preserving algorithms.These new adaptive algorithms are second order,and their algebraic order is carefully studied.Numerical results show that the global energy errors are bounded to the machine precision over long time using these adaptive algorithms without massive extra computation cost.

Study of Axisymmetric Infinite Guide Lined with Locally Reacting Material without Flow Using DtN Operators

The present work proposed a new method for the modeling by the finite element method of the acoustic propagation problems in infinite axisymmetric cylindrical guides lined with locally reacting absorbent materials without flow. The method deals with the development of an efficient transparent boundary condition based on DtN operators. The method developed in this study is successfully applied to a straight axisymmetric lined guide by imposing a mode on one of the artificial boundaries of the truncated guide. The results are in good agreement with analytical solutions. Applying the method for a non-uniform axisymmetric lined guide which is a complex case, proved its effectiveness and the results compared to those of PML layers are in very good agreement.

Clinical Observation on Brachial Plexus Block with “One Injection Two Points” Method Guiding by Ultrasound

OBJECTIVE: To compare the clinical effect of brachial plexus block with "One Injection Two Points" guided under ultrasound and the conventional method guiding by ultrasound. METHODS: 70 patients were randomized evenly into 2 groups, with 35 patients in each group, while the Experiment Group(Group B) received One Injection Two Points" method, the Control Group(Group A) received the conventional method.The nerve block every 5 s, the success rate of anesthesia, the dosage of local anesthetics, second remedial anesthesia, adverse reactions, etc.were recorded. RESULTS: Group B was superior to group A in the success rate of anesthesia; There were 6 patients in group A who required constant pump injection of Remifentanil to remedy, while no patients in Group B needed remedy treatment. There were no serious adverse reactions in both groups.CONCLUSIONS: The clinical effect of brachial plexus block with "One Injection Two Points" method guided under ultrasoundguiding by ultrasound was superior to that of the conventional method.

Theoretical investigation of band-gap and mode characteristics of anti-resonance guiding photonic crystal fibres

With the full-vector plane-wave method （FVPWM） and the full-vector beam propagation method （FVBPM）, the dependences of the band-gap and mode characteristics on material index and cladding structure parameter in anti- resonance guiding photonic crystal fibres （ARGPCFs） are sufficiently analysed. An ARGPCF operating in the near- infrared wavelength is shown. The influences of the high index cylinders, glass interstitial apexes and silica structure on the characteristics of band-gaps and modes are deeply investigated. The equivalent planar waveguide theory is used for analysing such an ARGPCF filled by the isotropic materials, and the resonance and the anti-resonance characteristics r：~n h~ w~｜] r^r~dlrtpd

AN ANALYSIS OF AND APPROACH TO THE METHOD FOR TESTING THE PARALLELISM OF SAW GUIDE MOTION LOCUS AGAINST THE BLADE

The parallelism of saw guide motion locus against the blade is one of the main iterns in the testing of the geometric precision of the whole woodworking band saxving-machine. It reflects the making and mounting precisions of the sawguide device,having a direct effect on the working performance. the saw timber quality. and the safety (nature) of the woodworking band sawing-machine, so it is of great importance in the testing process of the band sawing-machine assembly and their going out of the plant.

Motion Regular Analysis and Its Simulation of the Rodless Drilling Unit's Guiding & Positioning Board

To analyze the stress of the guiding & positioning board and the effectiveness of the guiding & positioning device,according to guiding & positioning device's operational principle and structure,the guiding & positioning board's motion regular was analyzed by diagrammatical method based on 2 postulated conditions.Considering about the working conditions' change,simulations in 5 different kinds of working conditions were done to check the correctness of the motion regulars obtained by diagrammatical method.Simulation results prove that the motion regulars are right,the postulated conditions have no effect on the obtained motion regulars.According to the simulation results,the motion processs's characters were drawn out at the same time.

Push vs pull method for endoscopic ultrasound-guided fine needle aspiration of pancreatic head lesions: Propensity score matching analysis

AIM To evaluate the efficacy of endoscopic ultrasoundguided fine needle aspiration(EUS-FNA) of pancreatic head cancer when pushing(push method) or pulling the echoendoscope(pull method).METHODS Overall, 566 pancreatic cancer patients had their first EUS-FNA between February 2001 and December 2017. Among them, 201 who underwent EUS-FNA for pancreatic head lesions were included in this study. EUS-FNA was performed by the push method in 85 patients, the pull method in 101 patients and both the push and pull methods in 15 patients. After propensity score matching(age, sex, tumor diameter, and FNA needle), 85 patients each were stratified into the push and pull groups. Patient characteristics and EUSFNA-related factors were compared between the two groups.RESULTS Patient characteristics were not significantly different between the two groups. The distance to lesion was significantly longer in the push group than in the pull group(13.9 ± 4.9 mm vs 7.0 ± 4.9 mm, P < 0.01). The push method was a significant factor influencing the distance to lesion(≥ median 10 mm)(P < 0.01). Additionally, tumor diameter ≥ 25 mm(OR = 1.91, 95%CI: 1.02-3.58, P = 0.043) and the push method(OR = 1.91, 95%CI: 1.03-3.55, P = 0.04) were significant factors contributing to the histological diagnosis of malignancy.CONCLUSION The pull method shortened the distance between the endoscope and the lesion and facilitated EUS-FNA of pancreatic head cancer. The push method contributed to the histological diagnosis of pancreatic head cancer using EUS-FNA specimens.

基于多特征SAD-Census变换的立体匹配算法

视差不连续区域和重复纹理区域的误匹配率高一直是影响双目立体匹配测量精度的主要问题,为此,本文提出一种基于多特征融合的立体匹配算法。首先,在代价计算阶段,通过高斯加权法赋予邻域像素点的权值,从而优化绝对差之和(Sum of Absolute Differences,SAD)算法的计算精度。接着,基于Census变换改进二进制链码方式,将邻域内像素的平均灰度值与梯度图像的灰度均值相融合,进而建立左右图像对应点的判断依据并优化其编码长度。然后,构建基于十字交叉法与改进的引导滤波器相融合的聚合方法,从而实现视差值再分配,以降低误匹配率。最后,通过赢家通吃(Winner Take All,WTA)算法获取初始视差,并采用左右一致性检测方法及亚像素法提高匹配精度,从而获取最终的视差结果。实验结果表明,在Middlebury数据集的测试中,所提SAD-Census算法的平均非遮挡区域和全部区域的误匹配率为分别为2.67%和5.69%,测量200~900 mm距离的平均误差小于2%;而实际三维测量的最大误差为1.5%。实验结果检验了所提算法的有效性和可靠性。

基于PSD的分离式长导轨直线度测量方法研究

利用分段拼接测量方法能够将PSD激光准直测量系统测量范围扩大,相较于传统长导轨直线度测量方法,该方法可同时适用于连续型导轨和分离式超长导轨的直线度测量。首先,在(-5~+5) mm测量范围内,通过激光干涉仪分别测得激光准直测量系统的接收靶在水平和竖直方向上的位移,误差均优于±(1μm+1%H)。然后,在40 m范围内与激光准直测量系统的直线度测量精度进行对比,二者水平方向直线度误差相差0.06 mm,竖直方向直线度误差相差0.13 mm。最后,在70 m分离式超长导轨上,测得水平方向直线度为0.50 mm,竖直方向直线度为0.53 mm。该方法可迅速定位和调整直线度误差极值点位置,能够较为有效地解决分离式超长导轨的直线度装配调试问题。

一种自适应强制进化随机游走算法应用于换热网络综合

RWCE(强制进化随机游走)算法应用于系统热集成时,最大步长既影响当前可行搜索域的范围,又影响整型变量的进化,固定参数设置降低了更优解产生的几率。因此提出一种融合自适应步长和自适应反向学习策略的RWCE算法。建立随机动态步长,在导向参数牵引下自动激励有利步长值持续进化;在此基础上,建立自适应反向学习策略改变个体进化路径,使算法在优化的不同阶段能够自动搜索最佳步长,并挖掘尽可能多的结构,充分发挥算法全局搜索和局部开发能力。最后研究并计算H6C10、H10C10、H13C73个典型中大规模算例,结果表明该方法能够进一步提升算法的寻优能力。

气相色谱内标法对糟烧白酒中甲醇含量的检测与应用

建立气相色谱内标法,检测糟烧白酒中的甲醇含量,此方法精确度、灵敏度、回收率均良好;对半成品和成品糟烧白酒中的甲醇含量作了比较,发现半成品糟烧白酒中甲醇含量较高,需作进一步的抽样检测,以指导生产,改良工艺。

超声引导下一步法行经皮经肝胆囊穿刺引流术在急性重症胆囊炎治疗中的应用

目的探讨超声引导下采用一步法行经皮经肝胆囊穿刺引流术(PTGD)在急性重症胆囊炎(ASC)治疗中临床效果。方法选择2020年1月至2023年5月在安徽医科大学第二附属医院接受PTGD治疗的ASC患者30例,其中男性19例,女性11例;年龄55~78岁,平均年龄67岁;病程42~64 h,平均病程55.77 h。行PTGD,统计视觉模拟量表(VAS)评分;对临床症状缓解患者行腹腔镜下胆囊切除术(LC)。比较其术前、术后第1天胆囊长径、胆囊宽径及术前、术后第1天、术后第3天感染指标变化;分析患者术后第1天、第2天、第3天腹痛缓解率;分析患者术后并发症发生情况。结果30例患者均一次性穿刺置管成功。术后第1天、第2天、第3天患者腹痛症状缓解率分为86.7%(26/30)、96.7%(29/30)和100.0%(30/30)。其中26例患者于术后5~6周后行LC。患者术后第1天胆囊长径、胆囊宽径均较术前减小[(76.58±8.62)mm vs(105.35±14.84)mm、(28.71±5.29)mm vs(41.25±3.41)mm。P<0.05]。患者最高体温、白细胞计数(WBC)、中性粒细胞比例(NEU%)、C反应蛋白(CRP)水平及VAS评分在术后第1天、术后第3天均较术前下降,且术后第3天低于术后第1天(P<0.05)。术后出现1例发生引流管脱管,1例胆汁引流不畅,但均未出现出血、胆汁漏、血气胸等严重并发症。结论在ASC的治疗中,采用超声引导下一步法行PTGD治疗可以减轻患者疼痛,改善炎症指标,降低术后并发症的发生。

改进型密集阵列全聚焦成像算法的碳纤维复合材料板损伤定位研究

本文针对各向异性碳纤维复合材料板的损伤定位问题,提出改进型密集阵列全聚焦成像方法。首先,考虑碳纤维复合材料板的各向异性,通过实验分析超声导波在板中的传播特性,得到沿不同传播方向的群速度值。其次,对密集型传感器阵列的参数进行分析和优化研究,分别对不同阵列参数即阵元间距和阵元数量进行指向性函数的数值分析,优化阵列的参数,以保证阵列主瓣较窄、旁瓣较低且无栅瓣。然后,提出了一种考虑碳纤维复合材料板各向异性的改进型密集传感器阵列板结构缺陷定位算法。使用超声导波在碳纤维复合材料板中沿不同传播方向的群速度值,对全聚焦算法进行修正,并利用虚拟聚焦原理对板结构进行全聚焦成像。最后,通过布置碳纤维复合材料孔洞损伤实验,对基于密集阵列全聚焦成像方法的定位精度进行分析。实验结果表明,改进型密集阵列全聚焦成像算法的定位精度为1.00 mm,相较于使用单一群速度值,该方法在定位孔洞损伤缺陷时具有更高的精度。

含初应力各向异性层合管纵向导波频散特性分析

基于勒让德级数法,联立增量变形理论,分析了含初应力各向异性层合管中纵向导波的频散特性,探讨了初应力场下导波传播的过程。相较传统级数展开法,通过利用正交完备性与递推特性,可有效地避免冗余的积分运算。基于所提联合理论方法,将其与不含应力的单层复合材料空心圆管纵向导波频散曲线进行对比,验证了所提理论方法的有效性。随后,数值计算了不同堆叠顺序下单向纤维层合管的导波频散曲线,揭示了中间层纤维角度对纵向导波频散特征的影响规律。最后,计算了不同初应力状态下的单向纤维层合管的纵向导波频散曲线,并讨论了初应力对各向异性层合管的纵向导波传播特性的影响规律。通过对比分析,为含初应力的各向异性层合管的无损检测与评估提供了理论支持。

青少年向复合阅读转向的引导策略

为探究全媒体环境下青少年向复合阅读转变过程中的阅读表现及其影响因素,并提出科学引导策略,文章运用混合方法研究收集青少年阅读的调查数据,对数据资料进行多角度多层次的深入分析。研究发现:青少年阅读整体上初显复合模式,阅读态度和家庭环境支持对青少年阅读行为表现产生显著的正向影响,阅读行为投入的内部反馈和外部结果又会影响他们的阅读态度,尤其是对个人兴趣驱动的休闲阅读态度产生显著影响;科学引导青少年向复合阅读转变的策略包括:根据阅读态度实施差异化的引导策略,加大家庭环境的支持力度,提供线上线下无缝衔接的服务体验。

“趣味引导,融合重构”推进兽医药理学教学创新改革

兽医药理学传统教学过程中,如何克服知识点繁复枯燥、思政元素孤立生硬、过程性评价参与度不高等挑战,是提高教学效果必须面对的一个问题。通过利用现代化信息平台,授课教师秉持“趣味引导,融合重构”的教学理念,通过多元化知识体系融合和探究式的课程设计,围绕学生的需求和兴趣切入教学,开展兽医药理学课程的教学改革。教师采用“5Q”教学法进行授课,引导学生主动探究和发现问题;加强课程思政建设,使学生在潜移默化中接受思想政治教育;通过对知识点进行模块化设计,形成“5M”课程内容体系;并通过构建四元教学评价体系,建立及时、精准的教学反馈机制。兽医药理学作为兽医学科的重要分支,其教学创新理念和实践具有较强的辐射推广价值。

大尺度圩田水网地区特色生态空间单元解析及传承策略研究——以高淳为例

我国幅员辽阔,各个地区的乡村空间各具特色。在诸如江浙一带的圩田水网地区便形成了独特的生态-聚落空间布局模式。文章以大尺度高淳水网地区的聚落空间为研究对象,在分析现状水系网络、农田体系、圩堤陆路等生态要素共同作用下的乡村特色空间基础上,从维持水田格局的特色性、分类引导聚落选址和堤路网体系优化布局三个方面,分别探究传承乡村特色空间的策略与导控方法,旨在为我国其他相似圩田水网地区的乡村特色空间传承提供实践指导方法和参考借鉴意义。

新型深海风机钢管桩基础安装用导向架结构优化

为解决水深45.000 m深海风机钢管桩基础安装作业可靠性差和精度低等问题,对一种新型深海风机钢管桩基础安装用导向架进行结构优化。采用有限元法(Finite Element Method, FEM)与试验相结合的方法,从环境参数与作用载荷、结构形式、作业工况和结构强度与结构稳定性等方面对导向架进行综合研究。经海试验证,优化的导向架的打桩精度与打桩高效性均满足技术指标要求,可大幅提高深海风机钢管桩基础安装作业速度和质量。

叶天士辛润通络法探析

辛润通络法肇源于《黄帝内经》,奠基于张仲景,发扬于叶天士,是治疗络病的大法。辛润通络法的核心内涵是“通而润之”,其运用当以“久、痛、瘀”为临床特征,以“邪滞络脉,阴血亏虚”为辨证要点,以“行津化瘀通络,滋润养血通补”为作用机制。研究叶天士辛润通络法相关医案,可以更好地理解其内涵和运用要点,为临床应用提供参考。

考虑云团衰减作用的激光制导炮弹弹道规划

针对多云天气条件下,云团对激光信号产生较大衰减作用从而影响末制导性能这一问题,提出一种考虑云团对激光衰减作用的滑翔增程激光制导炮弹弹道规划方法。经过合理假设建立云团近似模型,在此基础上设计云团规避—控制能量最优复合规避目标函数(Compound Evasion Objective Function,CEOF)。根据激光导引头工作特性和制导炮弹的飞行特性建立弹道规划模型,采用Radau伪谱法将弹道规划问题转化为非线性规划问题(Non-linear Programming,NLP)。调用NLP求解器SNOPT求解。选取多组云团算例进行仿真分析,仿真结果验证所提弹道规划方法的有效性。研究结果表明,与传统弹道规划方法进行仿真对比,新的弹道规划方法以增加较少动能损耗、控制能量消耗和攻击时长为代价,大幅减少了云团对激光的衰减作用,验证了其优越性。