Interaction Mechanisms between Natural Debris Flow and Rigid Barrier Deflectors:A New Perspective for Rational Design and Optimal Arrangement

Rigid barrier deflectors can effectively prevent overspilling landslides,and can satisfy disaster prevention requirements.However,the mechanisms of interaction between natural granular flow and rigid barrier deflectors require further investigation.To date,few studies have investigated the impact of deflectors on controlling viscous debris flows for geological disaster prevention.To investigate the effect of rigid barrier deflectors on impact mechanisms,a numerical model using the smoothed particle hydrodynamics(SPH)method with the Herschel–Bulkley model is proposed to simulate the interaction between natural viscous flow and single/dual barriers with and without deflectors.This model was validated using laboratory flume test data from the literature.Then,the model was used to investigate the influence of the deflector angle and multi-barrier arrangements.The optimal configuration of multi-barriers was analyzed with consideration to the barrier height and distance between the barriers,because these metrics have a significant impact on the viscous flow pile-up,run-up,and overflow mechanisms.The investigation considered the energy dissipation process,retention efficiency,and dead-zone formation.Compared with bare barriers with similar geometric characteristics and spatial distribution,rigid barriers with deflectors exhibit superior effectiveness in preventing the overflow and overspilling of viscous debris flow.Recommendations for the rational design of deflectors and the optimal arrangement of multi-barriers are provided to mitigate geological disasters.

Experimental Study on Vortex-Induced Vibration of Rough Risers with Coupling Interference Effect Under Side-by-Side Arrangement

A vortex-induced vibration(VIV)experiment of rough risers with coupling interference effect under a side-by-side arrangement was carried out in a wave-current combined flume.The roughness of the riser was characterized by arranging different specifications of surface attachments on the surface of the riser.Rough risers with three different roughnesses were arranged side by side with smooth risers to explore the VIV response of the riser under the combined action of roughness and interference effect,and to reveal the coupling mechanism between roughness and interference effect.The experimental results show that,compared with that of a smooth riser,the VIV of a rough riser under the coupling interference effect has a wider"lock-in"region,and the displacement decreases more significantly at a high reduced velocity,which is more likely to excite higher-order modes and frequency responses.In addition,the displacement response and frequency response of the smooth riser are not significantly affected by wake interference from the rough riser,which is caused by the decrease of the wake region due to the delay of the boundary layer separation point of the rough riser.

Experimental Study on Vortex-Induced Vibration of Rough Risers Coupling with Interference Effect in Tandem Arrangement

In order to study the response law of vortex-induced vibration(VIV)of marine risers under the combined action of roughness and interference effects,and to reveal the coupling mechanism of roughness and interference effects on the riser,a VIV experiment of rough risers in tandem arrangement was conducted in a wave−current combined flume.The experiment characterized the risers’roughness by arranging different specifications of attachments on the surface of the risers.Three rough risers with different roughness and smooth risers were arranged in tandem arrangement,with the rough risers arranged downstream.The experimental results indicate that the suppression of the attachments on the downstream risers’vibration are more significant both in the CF and IL directions as the reduced velocity increases.For the downstream riser,the amplitude response of rough riser is more significantly weakened compared with the smooth one at high reduced velocity.For the upstream risers,changes in the roughness and spacing ratio have an impact on their‘lock-in’region.When the roughness of downstream risers is relatively large(0.1300)and the spacing between risers is small(S/D=4.0),the reduced velocity range of‘lock-in’region in the CF direction of upstream risers is obviously expanded,and the displacement in the‘lock-in’region is severer.

Effects of Spatial Row Arrangement and Time of Planting Intercrops on Performance of Groundnut (Arachis hypogaea L.) under Maize (Zea mays L.)—Groundnut Intercropping System in Ejura

In monoculture, crop failure due to biotic or abiotic causes can result in partial or total output failure. The yield, socio-economic, and environmental effects of intercropping on the farmer and the environment as a whole have not received much attention. There is a dearth of knowledge on the productivity of maize-groundnut intercrops in Ghana regarding the relative timing of planting and spatial arrangement of component crops. Therefore, the objective of the study was to determine the effects of spatial row arrangement and the time of planting intercrops on the productivity of groundnut under maize-groundnut intercropping. The 5 × 3 factorial field experiment was undertaken at the Miminaso community in the Ejura-Sekyedumase municipality of the Ashanti Region of Ghana during the 2020 cropping seasons. Treatments were evaluated in a Randomized Complete Block Design (RCBD) with three replicates. The levels of row arrangement of intercrops were: one row of maize and one row of groundnut (1M1G), one row of maize and two rows of groundnut (1M2G), two rows of maize and one row of groundnut (2M1G), two rows of maize and two rows of groundnut (2M2G), sole maize and sole groundnut (M/G). The levels of time of introducing groundnut included simultaneous planting of intercrops (0 WAP), planting groundnut one week after planting maize (1 WAP) and planting groundnut two weeks after planting maize (2 WAP). There were significant (P 0.05) treatment interactions for pod and seed yields of groundnut throughout the study. The highest groundnut pod yields of 1815.00 kg/ha and 2359.00 kg/ha were recorded by the 0WAP × 1M2G treatment in the major and minor seasons of 2020, respectively, while the highest groundnut seed yields of 741.00 kg/ha and 726.00 kg/ha were recorded in the major and minor rainy seasons of 2020 by 1WAP × G and 0WAP × G treatments, respectively. The highest seed yields of groundnut (404 kg/ha and 637 kg/ha for major and minor rainy seasons, respectively) were produced by 1WAP × 2M2G.

Conductor Arrangement and Phase Sequence Optimization Scheme for 500 kV Four-Circuit Transmission Lines on Same Tower

The four-circuit parallel line on the same tower effectively solves the problems faced by the line reconstruction and construction under the condition of the increasing shortage of transmission corridors.Optimizing the conductor and phase sequence arrangement of multiple transmission lines is conducive to improving electromagnetic and electrostatic coupling caused by electromagnetic problems.This paper uses the ATP-EMTP simulation software to build a 500 kV multi-circuit transmission line on the same tower.It stimulates the induced voltage and current values of different line lengths,tower spacing,vertical and horizontal spacing between different circuits,phase sequence arrangement,and nominal tower height.Moreover,use the BP neural network optimized by a genetic algorithm to predict the induced voltage and current under the unknown conductor and phase sequence arrangement.Finally,based on multi-objective particle swarm algorithm to construct the optimization model of conductor arrangement scheme of overhead transmission line,combined with electromagnetic environment control index,determine the optimal conductor arrangement scheme by the size of particle fitness function,a significant reduction in induced voltages and currents between transmission lines and the four-circuit conductor layout scheme meeting the requirements of the electromagnetic environment is obtained,which provides a reference for the tower design of the transmission station project.

Generation of irregular particle packing with prescribed statistical distribution, spatial arrangement, and volume fraction

A method for packing irregular particles with a prescribed volume fraction is proposed.Furthermore,the generated granular material adheres to the prescribed statistical distribution and satisfies the desired complex spatial arrangement.First,the irregular geometries of the realistic particles were obtained from the original particle images.Second,the Minkowski sum was used to check the overlap between irregular particles and place an irregular particle in contact with other particles.Third,the optimised advance front method(OAFM)generated irregular particle packing with the prescribed statistical dis-tribution and volume fraction based on the Minkowski sum.Moreover,the signed distance function was introduced to pack the particles in accordance with the desired spatial arrangement.Finally,seven biaxial tests were performed using the UDEC software,which demonstrated the accuracy and potential usefulness of the proposed method.It can model granular material efficiently and reflect the meso-structural characteristics of complex granular materials.This method has a wide range of applications where discrete modelling of granular media is necessary.

Tooth arrangement design of retractable DTH hammer bit used for drilling while casing

Down-the-hole(DTH)hammer with casing while drilling(CWD)is a technology that has been proven to be able to alleviate many of the problems faced by complex formations.However,the drill bit is suffered from rapid wear,low drilling efficiency,and high energy consumption due to the unreasonable tooth arrangement and impact energy selection in drilling process,which affect the application effect of this technology.ABAQUS software was used for numerical simulation of rock breaking behavior under impact load with the single,three,and five teeth arrangement drill bit respectively,to improve the application effect and solve the aforementioned technical problems.Based on the calculated parameters of tooth arrangement,we designed a novel drill bit for hard rocks and provided a theoretical basis for the tooth arrangement of largediameter drill bits.

数字经济与实体经济融合的制度安排

数字经济与实体经济融合是建设现代化产业体系的现实需要,也是推动实体经济高质量发展的内在要求。然而,数据产权、交易、分配和治理制度不健全、核心技术存在短板、数字技术与传统产业脱节、寡头垄断平台“一家独大”、数字基础设施供求不匹配、数字鸿沟较大为数字经济与实体经济融合带来了现实挑战。数据要素制度、数字技术制度、数字产业制度、数字平台制度、数字基础设施制度可为数字经济与实体经济融合发展提供关键内核、强劲动能、生态体系、中介载体和坚实底座。因此,数字经济与实体经济走向深度融合需要加强相关的制度安排,未来应完善以“数据二十条”为核心的数据要素制度、“卡脖子”技术攻关制度、数字产业融合制度、数字平台治理制度、数字基础设施共投共建共享制度和数字鸿沟弥合制度。

广东音乐钢琴改编曲的艺术特色与演奏要义

中国钢琴作品的创作与发展已有百年历史,而广东音乐钢琴改编曲以广东音乐元素为基础,结合并借鉴西方钢琴创作技法,以其浓郁的岭南风韵,确立了在中国钢琴音乐中的重要地位。广东音乐钢琴改编曲在乐曲的风格、曲式、调性等方面独具一格,演奏起来也有别于其他国家和地区的钢琴改编曲。立足广东音乐钢琴改编曲的艺术特色与演奏要义,探索如何合理运用钢琴这一西洋乐器,展现广东音乐独特的神韵与意境。通过深入分析改编曲的创作背景、音乐风格和演奏技巧,提出有效的途径建议,以助于演奏者更好地理解和诠释优秀的广东音乐钢琴改编曲。

低透煤层瓦斯超前排放钻孔布置方式优化研究

目的为有效解决低透气性煤层瓦斯突出问题,有效消除阵列布孔方式带来的瓦斯排放盲区以及对角圆相切布孔方式造成的钻孔数量增加、重复排放等问题。方法通过理论分析,在超前排放钻孔有效排放半径一定的情况下提出阵列菱形法优化超前排放孔的布置方式(R为有效排放半径,煤层走向排放孔的间距为√3R),其钻孔数量约为对角圆相切法的3/4,重复排放面积减少至11%,减少了对角圆相切布孔方式的重复排放面积,减少了钻孔的数量。结果运用COMSOL Multiphysics对阵列菱形法布孔方式进行数值模拟运算,结果表明,阵列菱形法布孔方式排放20 d后,钻孔有效排放半径内整体瓦斯压力低于0.5 MPa,排放100 d后瓦斯压力低于0.30 MPa,卸压效果优于对角圆相切布孔方式的。将阵列法和对角圆相切法两种布孔方式排放100 d时钻孔周围的瓦斯压力分布情况与阵列菱形法布孔方式排放20 d时的分布情况交叉对比,发现阵列菱形法布孔方式卸压速率更快,卸压范围更广。结论提出阵列菱形法设计钻孔布孔方式,并运用COMSOL Multiphysics对3种钻孔布孔方式的卸压情况进行数值模拟运算,对比发现,阵列菱形法钻孔布孔方式比阵列法和对角圆相切法布孔方式更具优势,且在相同时间内卸压速率更快、卸压范围更广,对低透煤层预防瓦斯突出具有重要的意义。

集中式馈线自动化配电网供电可靠性评估

计及集中式馈线自动化的配电网可靠性评估尚存在较多研究空白,且多数研究仅计及故障停电的影响,在考虑预安排检修容量约束的情况下,计及负荷转供影响,结合馈线自动化的类型及运行逻辑,依据馈线自动化相关技术指标,对恢复供电过程中出现的负荷点进行详细分类,推导出不同类型负荷期望恢复供电时间和配电网供电可靠性指标计算公式。结合算例进行分析可知,不同终端配置下馈线系统平均停电持续时间SAIDI可减少0.95~1.08 h/(用户·a),说明了优化终端配置可有效提高配电网供电可靠性,证明了所提评估方法的准确性和实用性,并比较了不同终端配置对可靠性的影响。

服装裁片自动抓取技术及其布局方法的研究进展

为促进服装裁片自动化运输的发展,推动服装加工端完成产业升级,即“机器代人”,实现服装智能制造,综述了目前国内外服装裁片智能抓取技术及其布局方法的研究现状。具体分析了空压吸附式抓取,静电式抓取,针刺式抓取,机械手抓取和软体手指抓取的原理和特点,阐述了各抓取方式所适用的面料范围,将其在面料表面的布局方式总结为3类:盲式布局抓取、单点布局抓取和多点协同抓取。研究认为软体手指抓取技术具有更广阔的应用前景,并展望了服装裁片智能抓取技术的未来发展趋势,指出提高抓取准确率,提高抓取头的重复定位精度,研发便捷、高效、经济的布局方式,以及研发结合机器视觉技术等人工智能技术的智能抓取方式为未来的重要研究方向。

阵列式碳纤维复合材料的制备与微波吸收机理研究

以碳纤维为代表的碳材料具有质轻、导电性好、化学稳定性强等突出的物理化学性质,将其作为吸波剂使用可以提升材料的吸波性能、使用寿命并有效降低重量。通过“电场取向优化+基体灌封固化”的工艺完成了不同组分阵列式碳纤维复合材料的制备,采用SEM、FT-IR等手段对材料的形貌和化学成分进行表征,利用矢量网络分析仪对材料在2~18 GHz频段内的复介电常数和复磁导率进行表征,分析了微观结构对材料电磁参数、界面阻抗匹配及电磁波吸收性能的影响规律,最后研究碳纤维空间排布形式、复配粉体成分对其吸波性能的影响机制。结果表明,材料的电磁损耗机制由电介质损耗、干涉相消、界面极化弛豫、磁损耗共同构成;当复合材料厚度为2.0 mm时,反射率<-10 dB(6.1~7.6 GHz),在6.5 GHz处最大衰减值为-15.2 dB,热导率达到3.2 W/(m·K);验证所制备的材料在满足电磁波吸收功能的同时还具有一定的导热性。

资源编排视角下江苏“好苏嫂”发展策略研究

家政服务已经成为城市生活不可或缺的重要组成部分。本文以江苏省好苏嫂家庭服务有限责任公司为例,运用资源编排理论总结“好苏嫂”在资源管理中的成功经验,为中国家政企业的发展策略提供参考借鉴。

麦穗干插花加工型小麦种质资源的筛选

本研究以麦穗干插花(以下简称麦穗花)加工企业认可的云生1号、云麦53号品种为对照,采用芒长、穗长和茎秆强度3个加工企业认为影响麦穗花加工和销售的重要指标,对42份长芒小麦种质资源进行性状筛选与评价,并利用文献报道的与小麦茎秆强度相关的SSR分子标记对参试资源进行茎秆强度辅助选择,挑选出在农艺性状和分子遗传学上都适合加工麦穗花的优异种质资源,为云南干花产业发展提供新的原材料。结果表明,通过两年的田间种植观测与数据分析,未发现3个性状都较两个对照优异的资源。其中,C6(小黑麦)两年的芒长都较两对照显著优异且穗长和茎秆强度差异不明显或也显著优异,是比两个对照更适合加工麦穗花的优异资源;其次是C3和C9,两年的穗长和茎秆强度都显著优于或与两个对照差异不显著,也是加工麦穗花的较理想资源;C4、C5、C7和C8的穗长较云麦53号显著优异,芒长和茎秆强度则差异不显著或也显著优异。对茎秆强度的SSR分子标记辅助选择结果表明,C4、C6可能携带有与云麦53号相同的BARC59、BARC134和WMC48位点以及与云生1号相同的BARC59位点,C3、C5、C8也可能携带与云麦53号相同的BARC59、BARC134和WMC48位点以及与云生1号相同的BARC59、BARC358位点,C9可能携带有与云麦53号相同的BARC59、BARC134位点以及与云生1号相同的BARC59、WMC48位点。但是,用这些引物获得的分子标记结果与表型评价结果之间的一致性都在50%及以下,可能这些分子标记都不适宜用作供试小麦材料茎秆强度的辅助筛选。今后还需进一步筛选适合评价麦穗花加工型小麦种质资源的指标及分子标记,为选育满足生产需求的优良小麦品种提供技术支持。

三角形排列波浪锥柱绕流流动特性数值分析

采用大涡模拟方法,分析了亚临界雷诺数为3 900时三角形排列波浪锥柱的横流向间距比和顺流向间距比对其升阻力特性、尾流干涉效应及三维流动结构等的影响.结果表明,上游2个波浪锥柱的升阻力特性受下游波浪锥柱影响较小,下游波浪锥柱处于上游双波浪锥柱尾流中,其升阻力特性受横流向间距比和顺流向间距比影响更为显著.3个波浪锥柱间的流动状态可分为邻近干扰、漩涡撞击和涡相互作用状态.在漩涡撞击状态下,上游波浪锥柱尾涡得以发展充分,周期性撞击在下游波浪锥柱表面,从而产生较大的脉动升力.横流向间距比、顺流向间距比分别为3和6时,下游波浪锥柱脉动升力系数较单直圆柱提升了20.93倍.

RC框架梁端负弯矩纵筋部分置于梁侧楼板对性能的影响及构造问题分析

为适应建筑多功能、大跨度、重荷载、高抗震的发展要求,框架梁端部负弯矩纵筋配筋率通常较高,节点区钢筋过于密集,混凝土施工质量不易保证,对结构综合性能有不利影响。先对梁端负弯矩纵筋部分设置于梁侧楼板内(简称APNRFS)的布筋方式进行阐述,然后基于试验结果分析探讨了该配筋方式对结构性能带来的变化及相关构造问题。研究表明:梁端采用APNRFS布筋方式一般不会降低框架梁的承载力;梁端的弯曲变形能力和结构抗震性能有一定提高;移至板内的梁负筋布置宽度宜小于有效翼缘宽度范围;移至板内的梁端负筋宜同时兼作楼板负筋;横向分布筋参与受力,设计中应适当增配。

“一带一路”来华留学生全英文大学物理实验课程建设与实践

针对国家三部委提出的“推进来华留学生英语授课示范课程建设,全面提升来华学历学位留学教育质量”的要求,结合近年来中国矿业大学面向“一带一路”沿线国家来华留学生开设的“全英文大学物理实验”课程建设情况,探讨了实验绪论课程安排、实验项目的配置与调整、实验教学实施方式、学生管理及其课程成绩评定等关键环节的处理,并介绍了教材建设以及自主学习系统的开发建设情况。利用问卷调查对近年来的教学效果进行了分析评估,结果显示,学生总体对课程较为满意。希望本文的探讨能够为“全英文大学物理实验”课程的建设提供有益的参考。

认知负荷理论视域下教材插图编配研究

认知负荷理论是一种适合解释教材插图学习的理论,它认为学习者的学习活动主要在容量有限的工作记忆中进行,工作记忆有两条信息加工通道,分别负责处理文字内容和图片内容。有待工作记忆处理的文字内容和图片内容要彼此对应,编配方式应有利于学习者整合图文信息,且不宜让学习者的工作记忆负荷过重。在现行教材的代表性样本中,教材编配的大部分插图与文字内容相对应,教材主要采用嵌入、邻近、内容关联词、符号标志关联词等技术帮助学生建立插图与相应文字内容之间的联系,但插图与文字的有效关联技术运用得较少,教材插图的编配缺乏明确的规范。为规范教材插图的编配,应将“对应”作为插图选配的原则,适当提升嵌入技术的使用比例,充分且到位地运用图文关联技术,开展图文关联技术组合效果的研究,加强不同学科教材编写者在插图编配上的相互借鉴。

基于修正Loganathan公式的非水平布置双线平行盾构隧道施工引起土体位移计算方法

[目的]为研究双线平行盾构隧道非水平布置方式下,由施工引起的周围土体位移规律,提出一种基于修正Loganathan公式的土体位移计算方法。[方法]介绍了Loganathan公式及相关假设;考虑盾构隧道开挖扰动引起的地层损失、土体卸荷回弹和土体损失率沿掘进路径变化的综合影响,修正Loganathan公式并建立单线盾构隧道周围土体位移解;建立双线平行盾构隧道非水平布置方式下,由施工引起的土体位移计算方法;通过实际工程的现场监测和数值模拟结果,验证所提计算方法的工程适用性。[结果及结论]所提计算方法能够考虑隧道轴心连线与水平面夹角、双线隧道半径、隧道轴心间距、双线隧道埋深等双线隧道布置因素,以及隧道盾构施工扰动造成的地层损失、土体卸荷回弹和土体损失率沿掘进路径变化等施工因素对土体位移的影响。地面沉降及土体水平位移的理论计算结果同现场监测结果和数值模拟结果之间的平均误差分别为5.6%、0.6%和5.5%、5.3%,均满足工程经验规定的20%的精度要求,说明所提计算方法能够有效解决双线平行盾构隧道非水平布置方式下施工引起的土体位移计算问题,具有良好的工程适用性。