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.

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.

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.

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。

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。

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。

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。

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。

基于八步导学法的直播教学在乳腺外科教学中的应用

目的探究与分析基于八步导学法的线上直播教学方法在乳腺外科教学工作中的应用。方法选取2018年3月—2020年6月滨州医学院附属医院2018级及2019级乳腺外科专业的医学生86名作为研究对象,采取随机数字表法分为对照组与观察组,各43名,对照组给予传统多媒体线上直播教学,观察组在其基础上给予基于八步导学法的线上直播教学,对比2组医学生理论考试成绩、实践技能考试成绩、学习能力评分及对教学方法的评估。结果观察组理论考试成绩中理论成绩、病例分析成绩,实践技能中技能操作能力、健康宣教能力、沟通能力及人文素养成绩分别为(85.32±6.01)分、(80.16±6.87)分,(78.22±14.24)分、(77.98±13.54)分、(82.54±8.99)分、(80.05±6.74)分,医学生学习能力中自我管理能力、促进自主学习能力、促进学习积极性、促进生生互动、促进师生互动评分分别为(4.02±0.91)分、(4.03±0.82)分、(3.85±0.73)分、(4.11±0.85)分、(4.05±0.88)分,医学生认为技能操作配合好、认为反馈和指导正确、认为能够提高学习积极性与主动性、认为可巩固理论知识、认为可增强实践动手能力、认为可提高与患者的沟通能力、认为可提高面对患者时的能力与信心百分百分别为83.72%、86.05%、81.40%、95.35%、88.37%、93.02%、74.42%,观察组医学生的理论考试成绩、实践技能考试成绩、学习能力评分、对教学方法的评估均高于对照组,差异有统计学意义(P<0.05)。结论基于八步导学法的线上直播教学方法的构建及在乳腺外科教学工作中的应用,可明显提高医学生考试成绩,医学生的学习能力表现也较强,对教学方法的评价也较高。

采用矩阵束方法的复合材料圆管周向导波频散数据获取

基于矩阵束算法,提出了一种从弧形阵列采集数据中获取复合材料圆管多模态周向导波频散数据的方法。首先根据留数定理,给出了频率域导波响应信号的多模态周向导波叠加公式,构建了阵列导波信号的Hankel矩阵;然后通过求解Hankel矩阵的广义特征值获取了导波的频散数据,给出了综合利用正向和反向接收弧形阵列处理结果降低频散数据中噪声的方法;最后,设计了碳纤维复合材料圆管中周向传播导波信号的测量实验,利用矩阵束方法获取了圆管周向导波的频散数据,并与采用半解析有限元方法模拟的理论频散曲线进行了对比分析。理论频散曲线与实验数据吻合良好,表明该方法具有很强的鲁棒性,即使采用空气耦合换能器作为发射接收阵列,也可以有效地从弧形阵列波形信号中获取周向导波的频散数据。

无人潜航器解算目标运动要素的一种方法

随着计算机技术、人工智能、能源技术的发展,无人潜航器也被应用于军事领域。在分析了无人潜航器水下侦察搜索、反水雷战、水下诱骗战应用的基础上,提出潜艇采用线导方式控制双无人潜航器进行目标运动要素解算的方法,并分别通过图解法和计算法分析了其解算的原理。该方式只需探测目标的方位信息,降低了目标其他要素探测的难度,不仅增加了潜艇的探测距离还利于潜艇隐蔽,这对水下无人潜航器应用具有一定的参考意义。

小型多联装制导火箭弹弹道设计研究

提出了一火箭弹纵向平面内动力学模型,进行了一种基于伪谱法为的多联装制导火箭弹弹道设计;通过仿真算例对该方法进行了验证和分析。结果表明,该方法能够快速有效进行火箭弹多发连射时弹道设计,对于小型多联装制导火箭弹总体设计具有参考价值。

黄土地区PBA法暗挖车站快速施工关键技术研究

西安地铁何家营站是首次将“上四下二”六导洞PBA开挖工法应用于黄土地区的地下暗挖车站。群洞开挖本身具有较高的安全风险,而本项目工期紧张,需加快施工进度。利用MIDAS GTS NX对原导洞开挖方案进行优化,采用了上、下部导洞同时开挖、错距进行的方法。通过对比分析,结果表明:采用优化方案开挖时,地表沉降较小;上部边导洞的拱顶竖向变形明显增大,其余导洞的竖向变形均略小于原方案;上部边导洞的初支结构弯矩有小幅增长,其他导洞初支结构弯矩略有减小。通过技术经济指标对比分析,优化开挖方案在确保安全的前提下,能够极大提高施工效率,有效节约工期和费用。现场按优化方案开挖完成后,实测地表沉降未超出施工控制要求,且与计算结果较为吻合。

《临证指南医案》“通阳蠲饮法”辨治痰饮思路探析

探究叶天士“通阳蠲饮法”治疗痰饮的方药规律。叶天士认为痰饮病机属阳衰阴盛,饮邪上逆是痰饮病的典型特征。而治则方面,法遵仲景“温药和之”又多有发挥,认为温不是方法,而是目的,拓展温的概念为温阳、通阳、温养。治法方面,细化“通阳蠲饮法”为轻苦微辛开宣太阳、苦降辛通理运中阳、辛热淡渗温固肾阳。阐释叶天士治痰求本、重视宣畅气机、辨证四诊合参、详于三因制宜的个人特色。文章通过总结《临证指南医案》痰饮类案,管窥叶天士“通阳蠲饮法”治疗痰饮的方药规律,不揣谫陋,以飨诸君。

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。

基于AHP-模糊综合评价法的政府引导基金绩效评价研究

基于政府引导基金近年发展特点和相关政策要求,遵循政策导向性、重要性、层次性等原则,从项目决策、经济效益、管理水平、可持续性4个维度构建政府引导基金绩效评价指标体系,采用AHP-模糊综合评价法确定指标权重,并对山东省新旧动能转换基金进行绩效评价,结果表明该基金总体运营状况良好。最后针对评价中发现的问题提出相关政策建议。