Heuristic Expanding Disconnected Graph:A Rapid Path Planning Method for Mobile Robots

Existing mobile robots mostly use graph search algorithms for path planning,which suffer from relatively low planning efficiency owing to high redundancy and large computational complexity.Due to the limitations of the neighborhood search strategy,the robots could hardly obtain the most optimal global path.A global path planning algorithm,denoted as EDG*,is proposed by expanding nodes using a well-designed expanding disconnected graph operator(EDG)in this paper.Firstly,all obstacles are marked and their corners are located through the map pre-processing.Then,the EDG operator is designed to find points in non-obstruction areas to complete the rapid expansion of disconnected nodes.Finally,the EDG*heuristic iterative algorithm is proposed.It selects the candidate node through a specific valuation function and realizes the node expansion while avoiding collision with a minimum offset.Path planning experiments were conducted in a typical indoor environment and on the public dataset CSM.The result shows that the proposed EDG*reduced the planning time by more than 90%and total length of paths reduced by more than 4.6%.Compared to A*,Dijkstra and JPS,EDG*does not show an exponential explosion effect in map size.The EDG*showed better performance in terms of path smoothness,and collision avoidance.This shows that the EDG*algorithm proposed in this paper can improve the efficiency of path planning and enhance path quality.

Design of Cold-Junction Compensation and Disconnection Detection Circuits of Various Thermocouples and Implementation of Multi-Channel Interfaces Using Them-A Secondary Publication

Cold-junction compensation(CJC)and disconnection detection circuit design of various thermocouples(TC)and multi-channel TC interface circuits were designed.The CJC and disconnection detection circuit consists of a CJC semiconductor device,an instrumentation amplifier(IA),two resistors,and a diode for disconnection detection.Based on the basic circuit,a multi-channel interface circuit was also implemented.The CJC was implemented using compensation semiconductor and IA,and disconnection detection was detected by using two resistors and a diode so that IA input voltage became-0.42 V.As a result of the experiment using R-type TC,the error of the designed circuit was reduced from 0.14 mV to 3μV after CJC in the temperature range of 0°C to 1400°C.In addition,it was confirmed that the output voltage of IA was saturated from 88 mV to-14.2 V when TC was disconnected from normal.The output voltage of the designed circuit was 0 V to 10 V in the temperature range of 0°C to 1400°C.The results of the 4-channel interface experiment using R-type TC were almost identical to the CJC and disconnection detection results for each channel.The implemented multi-channel interface has a feature that can be applied equally to E,J,K,T,R,and S-type TCs by changing the terminals of CJC semiconductor devices and adjusting the IA gain.

Study on Scavenging and Disconnecting Effects of Nitrosation Reaction by Extracts of Tetradium Ruticarpum and Glycyrrhizae

In order to investigate and compare the effects of Tetradium ruticarpum and Glycyrrhizae extracts in terms of scavenging sodium nitrite and inhibiting N-ni- troso compounds formation, the 1_9（3^3） orthogonal test was conducted to extract the active components. In addition, the capacities of scavenging sodium nitrite and of in- hibiting the N-nitroso compounds formation were measured to confirm the optimum condition of extracting. When the scavenging rate was considered as the main index, the maximum capacities of scavenging sodium nitrite by the extracts of Tetradi- urn ruticarpum and Glycyrrhizae were 0.836 5 and 0.558 0, respectively. Further- more, when the disconnection rate was considered as the main index, the maximum capacities of inhibiting the N-nitroso compounds formation by the extracts of Tetradi- urn ruticarpum and G/ycyrrhizae were 0.922 8 and 0.625 6, respectively. As a re- suit, the capacity of inhibiting nitrosation reaction by Tetradium ruticarpum was shown to be much stronger than G/ycyrrhizae, no matter the scavenging rate or the disconnection rate as the main index to be considered.

A New Simulation Model for Recoil Analysis of Deep-Water Drilling Risers After Emergency Disconnection

The recoil response of a deep-water drilling riser following an ED(Emergency Disconnection)scenario is a transient and sensitive process.The recoiling displacement of the riser is the resultant of recoil motion and axial stretch.How-ever,it is typically represented by one variable in recoil simulations.As axial deformation is quite small compared with axial motion in the recoil process,it inevitably introduces numerical errors(i.e.,a large number annihilating a small number).Thus,it is hard to perform a quantitative analysis of axial deformation,although a consensus initial deformation is essential for recoil dynamics.Moreover,the triggered axial natural modes have never been examined before.In this study,the recoil response is decomposed into two parts:recoil motion and axial deformation,and a novel model is developed by Galerkin method.It has demonstrated that the initial stretch has a significant effect at the initial stage in recoil.The existing models underestimate the effects of axial deformation.The new model can capture information of triggered natural modes and figure out the modes undergoing dynamic compression.This study can be beneficial to overpull setting,determination of ED time and anti-recoil control optimization.

Gastroduodenal artery disconnection during liver transplantation decreases non-anastomotic stricture incidence

Background:The hepatic artery is the only blood source nourishing the biliary duct and associated with biliary complication after liver transplantation(LT).Gastroduodenal artery(GDA)disconnection increased proper hepatic artery flow.Whether this procedure attenuates biliary non-anastomotic stricture(NAS)is not clear.Methods:A total of 241 patients with LT were retrospectively analyzed.The patients were divided into the GDA disconnection(GDA-)and GDA preservation(GDA+)groups.Propensity score matching(PSM)was administrated to reduce bias.Logistic regression was conducted to analyze risk factors for biliary NAS before and after PSM.Postoperative complications were compared.Kaplan-Meier survival analysis and log-rank tests were performed to compare overall survival.Results:In all,99 patients(41.1%)underwent GDA disconnection,and 49(20.3%)developed NAS.Multivariate logistic regression revealed that GDA preservation(OR=2.24,95%CI:1.11-4.53;P=0.025)and model for end-stage liver disease(MELD)score>15(OR=2.14,95%CI:1.12-4.11;P=0.022)were risk factors for biliary NAS.PSM provided 66 pairs using 1:2 matching method,including 66 GDA disconnection and 99 GDA preservation patients.Multivariate logistic regression after PSM also showed that GDA preservation(OR=3.15,95%CI:1.26-7.89;P=0.014)and MELD score>15(OR=2.41,95%CI:1.08-5.36;P=0.031)were risk factors for NAS.When comparing complications between the two groups,GDA preservation was associated with a higher incidence of biliary NAS before and after PSM(P=0.031 and 0.017,respectively).In contrast,other complications including early allograft dysfunction(P=0.620),small-for-size graft syndrome(P=0.441),abdominal hemorrhage(P=1.000),major complications(Clavien-Dindo grade≥3,P=0.318),and overall survival(P=0.088)were not significantly different between the two groups.Conclusions:GDA disconnection during LT ameliorates biliary NAS incidence and may be recommended for application in clinical practice.

Layer stacked SiO_(x) microparticle with disconnected interstices enables stable interphase and particle integrity for lithium-ion batteries

Severe mechanical fractu re and unstable interphase,associated with the large volumetric expansion/contraction,significantly hinder the application of high-capacity SiO_(x)materials in lithium-ion batteries.Herein,we report the design and facile synthesis of a layer stacked SiO_(x)microparticle(LS-SiO_(x))material,which presents a stacking structure of SiO_(x)layers with abundant disconnected interstices.This LS-SiO_(x)microparticle can effectively accommodate the volume expansion,while ensuring negligible particle expansion.More importantly,the interstices within SiO_(x)microparticle are disconnected from each other,which efficiently prevent the electrolyte from infiltration into the interior,achieving stable electrode/-electrolyte interface.Accordingly,the LS-SiO_(x)material without any coating delivers ultrahigh average Coulombic efficiency,outstanding cycling stability,and full-cell applicability.Only 6 cycles can attain>99.92%Coulombic efficiency and the capacity retention at 0.05 A g^(-1)for 100 cycles exceeds99%.After 800 cycles at 1 A g^(-1),the thickness swelling of LS-SiO_(x)electrode is as low as 0.87%.Moreover,the full cell with pure LS-SiO_(x)anode exhibits capacity retention of 91.2%after 300 cycles at 0.2 C.This work provides a novel concept and effective approach to rationally design silicon-based and other electrode materials with huge volume variation for electrochemical energy storage applications.

Study of the Impact of Grid Disconnections on the Production of a Photovoltaic Solar Power Plant: Case of Diamniadio Power Plant

Today, renewable energy projects connected to the interconnected network, with powers of the order of tens of megawatts, are more and more numerous in sub-Saharan Africa. And financing these investments requires a reliable amortization schedule. In the context of photovoltaic systems connected to the interconnected electricity grid, the quintessence of damping is the amount of energy injected into the grid. Thus it is fundamental to know the parameters of this network and their variation. This paper presents an evaluation of the impact of power grid disturbances on the performance of a solar PV plant under real conditions. The CICAD photovoltaic solar plant, connected to the Senelec distribution network, with an installed capacity of 2 MWp is the study setting. An energy audit of the plant is carried out. Then the percentage of each loss is determined: voltage drops, module degradation, inverter efficiency. The duration of each disconnection is measured and recorded daily. The corresponding quantity of lost energy is thus calculated from meteorological data (irradiation, temperature, wind speed, illumination) recorded by the measurement unit in one-minute steps. The observation period is three months. The total duration of disconnections related to the instability of the electrical network during the study period is 46.7 hours. The amount of energy lost is estimated at 22.6 MWh. This represents 2.4% of the actual calculated production.

Morphogenesis of Floating Bone Segments: A Legacy of Serial Tensile Cross-Strut Microdamage in Trabecular Disconnection “Crumple Zones”?

Trabecular bone disconnection “hotspots” of real termini (ReTm) previously mapped as loci of weakness in the female aging spine and hip may be a source of free-floating cancellous segments found in the medullary space using a bespoke, thick slice histological method for identifying ReTm. A factor in their origin is apparently microdamage proliferation (differentiated by en bloc silver staining) with occasional callus moderation. Validation of similar “floating segments” (FS) in the ex-breeder rat suggested a pilot model for a potentially common phenomenon. Following marrow elution and density fractionation of the isolated floating segments from the whole proximal rat femora, scanning electron microscopy (SEM) and elemental microanalysis (EDS) was performed. The eluent contained numbers of vertically truncated, laterally branched floating segments (acute severance of sequential tensile cross-struts, causing chronic compression overload of axial-struts, with ii) inadequate stabilising callus, facilitating ReTm stacking into predetermined, substructural “crumple zones” of force containment, spheroidal attrition and particulate dissociation. As a catabolic outcome of altered tensile and hormonal influence, FS number may add a novel variable to cancellous bone kinetics particularly in women of relevance to fracture predisposition.

A Study of Digital Disconnection Among Older Adults in the Internet Age

With internet and smartphone usage increasing every year,seniors are being exposed to digital media,either actively or passively.To better integrate into the information society for the elderly,efforts are also needed to clarify the causes of their digital disconnection and develop appropriate solutions.In this study,semi-structured interviews are utilized to investigate the self-adjustment and external intervention of the elderly in the age of digital media and to explore the ways,causes,and effects of digital disconnection of the elderly.The focus issue of this study is to clarify the subjective and objective factors of digital disconnection,especially cognitive problems,group influences,and technological access barriers in the elderly population concerning digital devices and the Internet.

多间隔信息融合的母线保护电流互感器断线再开放策略

对于电流互感器(CT)断线后发生金属性故障的情景,现有母线保护采取的闭锁差动保护动作方式将会引发多个变电站停电。此外,当母线区内发生高阻接地故障时,现有母线保护判据可能会将其误判为CT断线故障,不利于电力系统的安全稳定运行。针对这一问题,提出了一种母线保护CT断线再开放策略,该策略基于断线间隔与非断线间隔的零序电流变化量对负荷波动和故障进行区分,并基于非断线间隔的差流有效值和间隔失灵保护信息对区内外故障进行判别。实时数字仿真系统仿真结果验证了所提CT断线识别判据和再开放策略的正确性。

基于ParFlow.CLM的居民小区屋顶雨水断接水文效应研究

城市不透水面的快速扩张极大地改变了自然的水文循环过程,是造成城市内涝、河湖生态退化等城市水问题的主要原因之一。海绵城市建设及低影响开发利用源头海绵设施或城市绿地断接城市不透水面,减少不透水面的水文效应,是缓解城市水问题的重要措施。探究不透水面断接的水文效应对我国海绵城市建设具有重要意义。基于全分布式物理水文模型ParFlow.CLM,充分考虑城市地下构筑物,探究了不同土壤质地情景下西宁市某典型居民小区建筑屋顶断接在连续的降雨、蒸发过程中的水文效应。模拟结果显示,利用该居民小区自然绿地断接建筑屋顶能取得较好的径流控制效果:当土壤饱和导水率(K_(s))大于0.01m/h时,屋顶径流的年削减率能达到72.9%以上。屋顶断接在建筑物雨落管附近形成了集中入渗,增加了根区土壤湿度,且这一效应随着土壤渗透性的增加而增强。根区土壤湿度的增加进一步促进了绿地的蒸散发:与屋顶断接前相比,不同土壤质地情景下居民小区年蒸散发总量增加了6.2%~7.8%。另一方面,集中入渗在局部也形成了更深的湿润锋,使得更多下渗水量能够脱离植被根区的蒸散发作用,从而促进根区水分的深层渗漏。模拟结果表明,尽管该居民小区地下停车场限制了大部分区域的深层渗漏,当土壤K_(s)大于0.01m/h时,屋顶断接情景下的年深层渗漏总量仍能超过城市化前的水平。

非连通空间对象方向关系表达与推理

为了弥补现有的二维空间对象方向关系表达模型大都利用点、最小外包矩形等近似地代替空间对象,距离真实空间对象间方向关系的描述与推理仍存在差距的不足,提出了一种基于Voronoi图的非连通空间对象方向关系表达模型。该模型借助Gestalt心理学理论,通过提取非连通空间对象的特征点、特征链,构建空间对象间的可视区域,生成方向关系Voronoi图,实现了非连通、含洞的参考对象与目标对象间方向关系的表达。该模型较好地顾及了空间对象形状、大小等因素带来的影响,表达精度更高、适用范围更广。为了提高复杂空间对象方向关系复合推理的精度,基于该模型提出了一个非连通对象间主方向关系复合推理算法。该算法借助Tile-union运算和Pr运算,实现了该模型下基本主方向关系的复合推理,降低推理结果的不确定性。分析和验证的结果表明,提出的非连通空间对象方向关系模型及复合推理算法,提高了表达与推理的精度,完善和提高了对复杂空间对象方位关系的分析与处理能力。

智能时代教育的离身性风险及其规避

智能时代,智能技术在教育领域的广泛使用既推动了教育的深层次变革,也带来了教育与身体分离的离身性风险。其具体表现为教育“订制式”倾向存在非涉身性风险、教育数字化倾向存在非体验性风险、教育环境虚拟化倾向存在弱情境性风险、师生关系异化存在去交互性风险。这些风险产生的根源在于智能时代的教育对身心二元论的固持、对教育工业化的崇拜、对全景敞视式规训的迷信、对泛在学习模式的盲从。针对智能时代的离身性风险,当前教育要基于“身体主体”,从四个方面规避相关风险:身心一体,注重发挥师生身体主体;知行合一,注重个体学习的体验性;主客交融,构建以实体为主、虚拟为辅的教育情境;师生双在场,建立身体交互主体。

架空线耐张线夹断连对安全备用线夹冲击试验及数值分析

为了探究耐张线夹断连时安全备用线夹承受的冲击载荷及线路关键位置的力学响应,建立了耐张线夹-安全备用线夹-导线耦联瞬断有限元模型。以JL/G1A-630/45-45/7导线为对象,模拟了耐张线夹断连后安全备用线夹单独承受冲击载荷的过程,分析多种档距和高差下耐张线夹断连后安全备用线夹关键位置张力变化。为了验证模型的有效性,开展了多组安全备用线夹受耐张线夹断连冲击试验。研究发现,高差与档距的增加会使安全备用线夹附近节点张力极值和导线振动周期增大。在档距500 m时张力极值和振动周期相较档距为150 m时分别增大了32.08%和140.23%。脱冰跳跃现象的发生会使安全备用线夹附近节点张力极值和导线振动周期减小。增大建立的有限元模型可用于耐张线夹断连冲击数值仿真,在工程当中为避免耐张线夹断连冲击对导线的损伤应减小大档距至500 m以下并降低悬挂点的高度。

经颈静脉肝内门体静脉分流术对肝硬化门静脉高压症患者门静脉直径及远期疗效的影响

目的探究经颈静脉肝内门体静脉分流术(TIPS)对肝硬化门静脉高压症(PHT)患者门静脉直径(PVD)及远期疗效的影响。方法选择2017年1月—2020年1月保定市第二中心医院收治的100例肝硬化PHT患者,利用随机数字表法分为对照组(50例,采用贲门周围血管离断术治疗)与研究组(50例,采用TIPS治疗),收集患者的临床资料并比较两组患者的肝脏血流动力学、肝功能及远期疗效。结果术前1 d,两组肝硬化PHT患者的PVD、门静脉血流量(PVF)、脾静脉内径(SVD)、脾静脉血流量(SVF)、门静脉流速(PVV)、脾静脉流速(SVV)、丙氨酸氨基转移酶(ALT)、天冬氨酸氨基转移酶(AST)及总胆红素(TBil)比较差异均无统计学意义(P>0.05);术后7 d,PVD[(1.15±0.22)cm vs(1.53±0.32)cm]、PVF[(774.45±101.28)mL vs(845.33±120.39)mL]、SVD[(1.17±0.21)cm vs(1.32±0.27)cm]、SVF[(304.47±63.38)mL vs(400.01±74.12)mL]、ALT[(38.45±8.61)U/L vs(50.26±10.05)U/L]、AST[(39.18±8.97)U/L vs(48.51±10.13)U/L]、TBil[(28.19±6.08)μmol/L vs(39.53±8.96)μmol/L]均降低(P<0.05),PVV[(45.69±9.98)cm/s vs(30.08±6.57)cm/s]及SVV[(24.76±6.02)cm/s vs(18.96±4.04)cm/s]均升高(P<0.05),且上述指标研究组改善更为明显(P<0.05)。两组肝硬化PHT患者的存活率随着术后时间的增加而降低,术后3年研究组的存活率明显高于对照组(P<0.05),并且,术后3年研究组的不良事件总发生率低于对照组,但两组之间差异无统计学意义(P>0.05)。结论TIPS治疗肝硬化PHT效果确切,可明显改善肝硬化PHT患者肝脏血流动力学及肝功能,对患者的远期疗效好。

一种基于磁耦合转移原理的10kV直流断路器

直流电流没有自然过零点,因此开断直流短路电流比开断交流短路电流更为困难。本文介绍一种基于磁耦合电流转移原理的中压10kV直流断路器拓扑方案,该断路器可实现对15kA直流电流的快速开断。首先,对直流断路器原理和控制逻辑进行介绍;然后,根据拓扑方案提出快速机械开关、电力电子开关、磁耦合装置等核心部件的设计思路;最后,搭建仿真模型对该方案进行仿真分析,模拟不同工况下的开断情况,仿真结果验证了该方案的有效性。

发电机解列时程序逆功率保护动作行为分析

在发电机组解列过程中出现程序逆功率保护未及时动作的异常情况,为了保证发电机组运行安全,通过对程序逆功率保护的动作过程、保护的整定原则和动作逻辑进行分析,找到了发生异常的原因,并提出了处理原则和预控措施。

“断亲”为何?--试论中国人际关系的变迁

当前中国社会出现的断亲现象,理论上可区分为宏观意义上的一般性解释、中层意义上的跨文化以及社会学本土化中的“关系性”解释。从人情与面子的研究框架出发予以审视,以往的各种理论均倾向于从社会结构角度解释这一现象,即认为“断亲”是由工业化、城市化、市场化所引发的社会流动导致的个体化结果。而人情与面子的研究框架则将此种社会现象指向行动主体的主观意图,即如果一个人的地方社会网络能够给其带来充沛的社会资源,那么他不会采取“断亲”行为;当一个人从其原有的地方网络中无法获得他所要的社会资源,或此资源已派不上用场时,其依附性便随之消失。但这并不意味着关系本身不再重要,因为现代性社会生活会使人们在自己的生活或事业领域重建自己的社会网络,“断亲”只是表示与旧有的亲属网络不再发生联系。

系统不确定的深海钻井立管解脱反冲智能控制

深海钻井立管系统紧急解脱后的反冲控制是深海油气钻探中的必备技术,但系统动力参数在多方面具有不确定性与难测性,给实际反冲控制带来了严峻挑战.建立系统模型不确定条件下的立管反冲智能自适应控制方法,通过反冲控制名义状态空间方程与闭环系统稳定性推导考虑模型不确定的修正控制输入,采用径向基(RBF)神经网络逼近模型不确定部分并选取满足李雅普诺夫(Lyapunov)稳定的权值自适应律,实现控制输入中对不确定部分的动态补偿.结果表明:该方法适用于实际反冲控制阀有调控速度限制的情况;张紧器刚度、阻尼、钻井液下泄摩擦力及立管浮力载荷等不确定性对反冲动力响应及控制效果均有一定影响;无论系统参数是否精确,经过RBF自适应控制后都降低了反冲初期振荡高度且降低了反冲触底风险.研究成果可有效解决工程背景下缺乏准确系统参数的立管反冲控制难题.

内转塔式单点系泊系统解脱施工方案研究

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