Strengthening the three-dimensional comprehensive observation system of multi-layer interaction on the Tibetan Plateau to cope with the warming and wetting trend

Changes in the water cycle on the Tibetan Plateau(TP)have a significant impact on local agricultural production and livelihoods and its downstream regions.Against the background of widely reported warming and wetting,the hydrological cycle has accelerated and the likelihood of extreme weather events and natural disasters occurring(i.e.,snowstorms,floods,landslides,mudslides,and ice avalanches)has also intensified,especially in the highelevation mountainous regions.Thus,an accurate estimation of the intensity and variation of each component of the water cycle is an urgent scientific question for the assessment of plateau environmental changes.Following the transformation and movement of water between the atmosphere,biosphere and hydrosphere,the authors highlight the urgent need to strengthen the three-dimensional comprehensive observation system(including the eddy covariance system;planetary boundary layer tower;profile measurements of temperature,humidity,and wind by microwave radiometers,wind profiler,and radiosonde system;and cloud and precipitation radars)in the TP region and propose a practical implementation plan.The construction of such a three-dimensional observation system is expected to promote the study of environmental changes and natural hazards prevention.

Geologic body three-dimensional model generation and visualization method

The divergence three-dimensional millet-seed body model and the continuous distributing layer-imitating model were introduced, which were used to express geologic body, and the procedure of generating these two models and their merits and demerits were synthesized. Three methods of geologic body’s three-dimensional expression were separately introduced, and the merits of the continuous distributing layer imitating model were proposed as comparing with the divergence three-dimensional millet-seed body model. The three-dimensional cubes were observed from any direction and any tangle with the application of dealing methods such as peeling, hollowing out, transparent or half-transparent.

Three-dimensional analysis of pedicle screw channel,screw entry point and lateral surface of cervical vertebral body

Objective To explore three-dimensional relations of pedicle screw channel (PSC) ,screw entry point and lateral surface of cervical vertebral body by digital techniques. Methods CT scan images of cervical

FINITE-PART INTEGRAL AND BOUNDARY ELEMENT METHOD FOR INTERACTION BETWEEN TWO PARALLEL PLANAR CRACKS IN THREE-DIMENSIONAL FINITE BODIES

By using the Somigliana representation and the concepts offinite-part integrals, a set of hypersingular integral equations ofthe interaction between two parallel planar cracks in a three-dimen-sional finite body subjected to arbitrary loads is derived, and thenits numerical method is proposed by the finite-part integral methodcombined with the boundary element method. According to the analytictheory of hypersingular integral equations, the square root models ofdisplacement discontinuities in the elements near the crack front areapplied, and thus the computational precision is raised. Based onthis, the stress intensity factors can be directly calculated.Finally, the stress intensity factors of sever- al typicalinteraction problems are calculated.

Three-dimensional experimental study of loose top-coal drawing law for longwall top-coal caving mining technology

Based on the loose medium flow field theory, the loose top-coal drawing law of longwall top-coal caving（LTCC） mining technology is studied by using self-developed three-dimensional（3D） test device. The loose top-coal drawing test with shields and the controlled test without shields are performed in the condition without any boundary effect. Test results show that shields will cause reduction in drawing volume of coal in the LTCC mining. The deflection phenomenon of drawing body is also observed in the controlled test, which is verified that the deflection of drawing body is caused by shield. It is found that the deflection angle decreases with increasing caving height, with the maximum value of atailand the minimum value of 0. In addition, the formula to calculate the drawing volume is proposed subsequently.The deflection of drawing body is numerically simulated using particle flow code PFC3 Dand the proposed formula to calculate drawing volume in LTCC is also verified.

Three-Dimensional Prototypes and Evaluation of Their Structure and Form

In order to reveal the appearance of the clothing prototype on the human body,the characteristics of the human body’s structure above the waist section were studied.Based on the experimental data of the fit prototype,three-dimensional prototypes features were comparatively analyzed.And then objectively evaluating the relationship was conducted between the planar structure lines of different prototypes and the human body.The results showed that the prototypes analyzed basically conformed to the size of the human body.However,when they were worn on the human body,there were problems in the structure and forming.The main reason was that the side seam was skewed to different degrees.The results of this study provide reference for many practitioners to choose prototypes.

准确影像定位在颈部食管腔外异物取出术的应用

目的分析颈部食管腔外异物的临床特点及准确影像定位在其诊断和治疗中的应用。方法回顾性分析2017年10月~2024年3月梅州市人民医院耳鼻咽喉科收治的10例颈部食管腔外异物患者,对颈胸部CT行多平面重建(multiplanar reconstruction,MPR),从横断位、冠状位、矢状位判断异物位置,选择合适的手术入路。结果10例颈部食管腔外异物,2例金属和1例木质异物为外伤进入颈部,7例鱼骨为误吞鱼骨迁移颈部。术前影像定位提示异物在环状软骨和甲状软骨周3例,甲状腺内1例,相对应颈椎周2例,胸锁乳突肌周2例,舌骨周2例。支撑喉镜下取出2例,经颈部切开入路取出7例,1例未取出转上级医院治疗。术中彩超协助定位3例。所有患者随访至今均痊愈。结论准确影像定位可为颈部食管腔外异物选择合适手术入路提供依据,术中若异物寻找困难,可借助术中彩超精确定位异物,为成功取出异物提供有力保障。

裂隙影响下的微润灌水分运移和分布规律

为研究裂隙发育对微润灌水分运移和分布特征的影响规律,进行了室内土箱水分入渗试验.通过人造裂隙方式,设置不同裂隙间距(6,8 cm)和裂隙深度(5,10,15 cm)处理,同时以无裂隙处理(CK)为对照,测定了入渗过程中入渗量变化、湿润体形态演变和入渗结束时水分分布特征.结果表明:裂隙对微润灌水分入渗速率基本无影响,各处理之间累积入渗量随入渗时间变化趋势接近,最终累积入渗量差异不显著.裂隙改变湿润体形态演变和水分分布特征,湿润锋到达裂隙区域后,在裂隙毛管阻隔效应影响下,水分水平运动受到抑制,向上运动得到加强,最终导致湿润体上部呈近似矩形、下部呈近似椭圆,剖面水分分布呈指状特征.裂隙深度对湿润体规则度、湿润锋向上运移距离和灌后水分分布均匀度影响显著,而裂隙间距对其影响不显著.相比CK,裂隙深度15 cm时湿润体分散度约增加了34.5%,湿润锋最终向上运移距离约增加了12.9%,水分分布均匀度约降低27.5%.综合考虑,在微润灌实际应用过程中应控制田间裂隙深度发育,以降低其不利影响.

改良剂作用下盐碱土水盐运移试验研究

为研究不同改良剂对滴灌条件下盐碱土中水盐运移的影响,通过室内双点源土柱入渗试验,探究在相同滴头流量(0.3 L/h)不同改良剂条件下,土柱中湿润峰的变化及湿润体内水分和盐分的运移情况。研究结果表明:改良剂的添加对水分的减渗作用明显,尤其是采用施用量为1.0 g/kg的腐殖酸处理的土壤,垂直湿润锋最深到达距地表11 cm处,较不添加改良剂的对照组小了9 cm;改良剂显著增加了湿润体平均体积含水率与脱盐率,与对照组相比,采用施用量为1.0 g/kg的腐殖酸处理的土壤湿润体平均体积含水率提高了28%、脱盐率提高了20%;采用施用量为1.0 g/kg的生物菌处理的土壤平均体积含水量提高了4%、脱盐率提高了15.1%。在相同滴头流量下,虽然经施用量为1.0 g/kg的腐殖酸处理的土壤湿润体平均体积含水量最高、脱盐率最好,但湿润体最小、脱盐范围最小且会产生地表积水,从而造成水分的浪费。综合来看,采用施用量为1.0 g/kg的生物菌改良的土壤比较适合宁夏南梁农场种植油葵、玉米等扎根较深的耐旱作物。

Inducing human induced pluripotent stem cell differentiation through embryoid bodies:A practical and stable approach

Human induced pluripotent stem cells(hiPSCs)are invaluable resources for producing high-quality differentiated cells in unlimited quantities for both basic research and clinical use.They are particularly useful for studying human disease mechanisms in vitro by making it possible to circumvent the ethical issues of human embryonic stem cell research.However,significant limitations exist when using conventional flat culturing methods especially concerning cell expansion,differentiation efficiency,stability maintenance and multicellular 3D structure establishment,differentiation prediction.Embryoid bodies(EBs),the multicellular aggregates spontaneously generated from iPSCs in the suspension system,might help to address these issues.Due to the unique microenvironment and cell communication in EB structure that a 2D culture system cannot achieve,EBs have been widely applied in hiPSC-derived differentiation and show significant advantages especially in scaling up culturing,differentiation efficiency enhancement,ex vivo simulation,and organoid establishment.EBs can potentially also be used in early prediction of iPSC differentiation capability.To improve the stability and feasibility of EB-mediated differentiation and generate high quality EBs,critical factors including iPSC pluripotency maintenance,generation of uniform morphology using micro-pattern 3D culture systems,proper cellular density inoculation,and EB size control are discussed on the basis of both published data and our own laboratory experiences.Collectively,the production of a large quantity of homogeneous EBs with high quality is important for the stability and feasibility of many PSCs related studies.

Effects of lower body positive pressure treadmill on functional improvement in knee osteoarthritis:A randomized clinical trial study

BACKGROUND Knee joint pain and stiffness are the two main symptoms of knee osteoarthritis(OA)and thus restrict a patient’s activities,such as walking and walking up and downstairs.The lower body positive pressure(LBPP)treadmill as one of the emerging body weight support system devices brings new hope for exerciserelated rehabilitation for knee OA patients.AIM To investigate the biomechanical effects and the subjective clinical assessment of LBPP treadmill walking exercise when compared with conventional therapy in mild to moderate knee OA patients.METHODS Eighteen patients with mild-to-moderate knee OA were recruited in this randomized controlled trial(RCT)study.The eligible knee OA patients were randomly assigned to two groups:LBPP and control groups.The patients in the LBPP group performed an LBPP walking training program for 30 min/session per day,6 d per week for 2 wk whereas the patients in the control group performed walking on the ground for the same amount.All patients underwent clinical assessments and three-dimensional gait analysis at pre-and 2-wk post-treatment.RESULTS The Western Ontario and McMaster Universities Arthritis Index and visual analog scale scores in both the LBPP group and control group were found to decrease significantly at the post-treatment point than the pre-treatment point(LBPP:70.25±13.93 vs 40.50±11.86;3.88±0.99 vs 1.63±0.52;control:69.20±8.88 vs 48.10±8.67;3.80±0.79 vs 2.60±0.70,P<0.001).Moreover,compared with the control group,the LBPP group showed more improvements in walking speed(P=0.007),stride length(P=0.037),and knee range of motion(P=0.048)during walking,which represented more improvement in walking ability.CONCLUSION The results of our RCT study showed that the LBPP group has a greater effect on improving gait parameters than the conventional group,although there was no significant advantage in clinical assessment.This finding indicates that LBPP treadmill walking training might be an effective approach for alleviating pain symptoms and improving lower extremity locomotion in mild to moderate knee OA patients.

硫酸盐快速干湿循环条件下MKPC硬化体的试验研究

为研究硫酸盐快速干湿循环条件下磷酸钾镁水泥(MKPC)浆体的性能。取MKPC净浆空白组(M1)、单掺石灰石(M2)、单掺硅灰(M3)以及双掺石灰石和硅灰(M4)4种MKPC浆体试件,在5%Na2SO4溶液进行全浸泡以及快速干湿循环。试验结果表明:在Na2SO4中浸泡90 d后,M1~M4的抗压强度相比自然养护28 d的抗压强度提高38.13%,46.10%,53.58%,83.30%,质量损失为1.69%,1.33%,1.09%,1.02%;180次的快速干湿循环后,M1~M4的抗压强度相比自然养护28 d的抗压强度提高16.79%,27.11%,39.92%,71.57%,质量损失为1.93%,1.48%,1.11%,1.09%。M1~M4试件的耐腐蚀系数均大于0.75,分别为0.85、0.87、0.91、0.94;添加矿物掺合料可较好改善MKPC硬化体在硫酸中的有抗压强度、质量损失以及耐腐蚀系数,说明MKPC硬化体具有良好的耐腐蚀性能。

膜下滴灌条件下沟垄规格对水分运移过程影响研究

沟垄栽培措施为重要的农艺耕作方式,研究膜下滴灌条件下沟垄规格对土壤水分运移的影响有利于提高水分利用效率。通过室内土箱模拟试验,探究了沟底宽度等沟垄规格参数对土壤湿润体的形状及水分分布的影响,采用多元线性回归方程构建了湿润锋运移距离模型,模拟了试验工况下土壤水分输运过程,并验证了模型的预测效果,最后基于构建的运移距离模型确定了试验工况下3 a生枸杞栽培种植最优沟垄规格。研究结果表明:随着沟底宽度的增加,湿润体形状愈发扁平,湿润体中水分分布重心会随沟底宽度的增加而逐渐上移;土壤含水率等值线分布图与湿润体形状图大致相似,呈由密至疏分布格局;构建的湿润锋运移距离模型预测的水分运移距离与试验结果误差较小,模型精度较高;试验工况下,采用膜下滴灌技术的3 a生枸杞栽培种植最优沟底宽度为22.50~28.90 cm。

Numerical aerodynamic analysis of bluff bodies at a high Reynolds number with three-dimensional CFD modeling

This paper focuses on numerical simulations of bluff body aerodynamics with three-dimensional CFD(computational fluid dynamics) modeling,where a computational scheme for fluid-structure interactions is implemented.The choice of an appropriate turbulence model for the computational modeling of bluff body aerodynamics using both two-dimensional and three-dimensional CFD numerical simulations is also considered.An efficient mesh control method which employs the mesh deformation technique is proposed to achieve better simulation results.Several long-span deck sections are chosen as examples which were stationary and pitching at a high Reynolds number.With the proposed CFD method and turbulence models,the force coefficients and flutter derivatives thus obtained are compared with the experimental measurement results and computed values completely from commercial software.Finally,a discussion on the effects of oscillation amplitude on the flutter instability of a bluff body is carried out with extended numerical simulations.These numerical analysis results demonstrate that the proposed three-dimensional CFD method,with proper turbulence modeling,has good accuracy and significant benefits for aerodynamic analysis and computational FSI studies of bluff bodies.

土石混合土层注浆固结体崩解特性研究

为研究元阳老虎嘴滑坡区梯田土石混合体注浆后固结体崩解特性,本文对元阳梯田土石混合体进行室内模型注浆后取样养护,再进行室内干湿循环崩解试验分析。结果表明:注浆固结体的崩解主要是未受浆液胶结或胶结弱的石块或土颗粒的崩解损失,且距离注浆孔越远,崩解掉落损失的土块直径越大;固结体前3次崩解的崩解速度最快,之后崩解速度变缓;注浆压力变大,崩解率会变小,但注浆压力增大幅度仅为0.1 MPa时对固结体的崩解改善作用并不是很明显;存在一个介于0.8~1.0之间的临界水灰比,当水灰比小于临界值时,同一压力下固结体崩解率随水灰比增大而减小,反之当水灰比大于临界值时,同一压力下固结体崩解率随水灰比增大而增大;对于注浆压力大的注浆固结体,养护时间变大能改善固结体崩解性,注浆压力小时养护时间对崩解性无影响。建议此次工程选择注浆压力0.45 MPa、水灰比0.8的注浆参数,固结体抗崩解性最好。

节能高效商用车车身涂装工艺的设计与应用

针对目前商用车车身涂装工艺的高能耗、环境不友好、生产效率低等问题,对商用车车身涂装材料和工艺进行优化选型。采用硅烷处理剂、高泳透力电泳涂料、“湿碰湿”涂装用胶、高固面漆等新材料,设计出一套节能高效的商用车车身涂装新工艺。

地下滴灌土壤水分运移与分布研究进展

地下滴灌条件下土壤水分运移与分布规律一直是学术界追踪的热点课题。为明确地下滴灌条件下土壤水分运移与分布影响因素的研究进展,总体概览了地下滴灌技术的基本原理、主要特点以及发展历程,系统阐述了不同地下滴灌方式下土壤水分运移与分布研究方法及结论,并介绍数值仿真技术在土壤水分分布规律研究中的应用现状,综合分析了地下滴灌条件下影响土壤水分运移与分布的关键因素,总结了当前研究现状与发展瓶颈,并对未来研究方向进行展望,以期为后续深入研究和提高灌溉水分利用率提供理论参考。

STUDY OF THREE-DIMENSIONAL SEPARATION OF BOUNDARY LAYER OVER BLUNT BODIES

In the case of three-dimensional flows, the separation can be defined in more than one way. Discussions about three-dimensional boundary layer separation in the literature have found a rational extension of the zero skin friction. Attempts have been made to establish the identity of “separation lines”. Among definitions, these may be found： （1） envelopes of limiting streamlines, （2） lines dividing flow which has come from different regions, （3） lines of singularities （problems of topology）, （4） lines on which some component of the skin friction vanishes. Each of these is valid under certain conditions, but none is universally valid. In the present work, we use the definition （4）, i.e. at low incidence of a blunt body the separation line is identified as the zero of the meridian skin friction component （Wang 1975）. So the separation line on a flattened spheroid （6：3：1） at 6° of incidence is calculated, as well as experimentally determined by using the electrochemical method, which allows to follow the evolution of the parietal velocity gradient.

微润灌溉土壤湿润体运移模型研究

为探明微润灌溉土壤入渗湿润体运移的变化规律,采用室内土箱模拟的方法,以粘壤土为例,选取不同土壤容重、初始含水率、管带埋深和压力水头等4个因素进行试验,研究这些因素对微润灌土壤入渗湿润锋随时间运移关系的影响。结果表明:在相同入渗时间内,湿润锋运移距离随土壤容重的增大而减小,随土壤初始含水率和压力水头的增大而增大,但不同管带埋深对湿润锋运移无显著影响;湿润锋垂直和水平方向运移距离与时间的1/2次方呈线性函数关系,以此为基础建立了包括土壤容重、初始含水率和压力水头的综合预测模型,用建立的综合模型对微润灌土壤入渗湿润锋运移距离进行预测,并对预测值与试验值进行比较,结果表明综合模型的预测精度较高。

涌泉根灌土壤湿润体运移模型

为了探明涌泉根灌土壤入渗湿润体运移的变化规律,以黏壤土为例,在室内选取不同土壤容重、初始含水率、灌水器套筒透水部长度和埋深等4个因素进行试验,研究这些因素对涌泉根灌土壤入渗湿润锋随时间运移关系的影响.结果表明:土壤入渗湿润锋运移速率随土壤容重的增大而减小,随土壤初始含水率的增大而增大,随套筒透水部管长的增长而增大,但不同埋深对灌水器湿润锋的推进速度无显著影响,涌泉根灌土壤入渗湿润体随时间的运移符合幂指数关系,幂指数在水平和垂直向分别为0.32和0.2.以此为基础分别建立了湿润锋在水平和垂直向运移距离的预测模型,并建立了包括土壤容重、初始含水率和灌水器套筒透水部长度的综合预测模型.用建立的综合模型对涌泉根灌土壤入渗湿润锋运移距离进行预测,并对预测值与试验值进行了比较后得出,综合模型的预测精度较高.