Bi-directional interaction of joint shear strength in non-seismically designed corner RC beam-column connections under seismic loading

Non-seismically designed(NSD)beam-column joints are susceptible to joint shear failure under seismic loads.Although significant research is available on the seismic behavior of such joints of planar frames,the information on the seismic behavior of joints of space frames(3D joints)is insufficient.The 3D joints are subjected to bi-directional excitation,which results in an interaction between the shear strength obtained for the joint in the two orthogonal directions separately.The bi-directional seismic behavior of corner reinforced concrete(RC)joints is the focus of this study.First,a detailed finite element(FE)model using the FE software Abaqus,is developed and validated using the test results from the literature.The validated modeling procedure is used to conduct a parametric study to investigate the influence of different parameters such as concrete strength,dimensions of main and transverse beams framing into the joint,presence or absence of a slab,axial load ratio and loading direction on the seismic behavior of joints.By subjecting the models to different combinations of loads on the beams along perpendicular directions,the interaction of the joint shear strength in two orthogonal directions is studied.The comparison of the interaction curves of the joints obtained from the numerical study with a quadratic(circular)interaction curve indicates that in a majority of cases,the quadratic interaction model can represent the strength interaction diagrams of RC beam to column connections with governing joint shear failure reasonably well.

Effect of Dietary Components on the Shear Bond Strength of Orthodontics Brackets after Thermal Aging

Introduction: The stability of orthodontic brackets throughout orthodontic treatment plays a critical role in the treatment’s effectiveness. The present in vitro study was designed to assess the impact of various dietary components on the performance of orthodontic brackets. Methods: Metal orthodontic brackets were bonded to 66 extracted anterior teeth divided into groups based on the solution type: Milk, Gatorade, Cold Coffee, and a control group using water. Each group consisted of 20 teeth except for the control group, which included six teeth. The bracketed teeth were submerged in their respective solutions for 15 minutes three times daily at different intervals to mimic an in vivo environment and were stored in artificial saliva at room temperature (23?C). The specimens underwent artificial aging through 10,000 cycles of thermocycling (representing one clinical year) between 5?C and 55?C. Shade measurements were taken using a VITA Easy Shade device, capturing the classic shade and L*, a*, and b* values. Delta E values were calculated immediately post-bonding and after 7 days, 1 month, 1, and 2 clinical years. The shear bond strength of each bracket was measured using an ultra-tester machine. Results: After two clinical years, significant differences in ΔE color values were observed across all groups, with the most substantial change noted in teeth immersed in cold coffee. Brackets submerged in milk demonstrated lower shear bond strength than other solutions, whereas the control group exhibited the highest shear bond strength (P = 0.01). Conclusion: The study indicates that dietary components significantly influence tooth color stability and the shear bond strength of orthodontic brackets, underscoring the importance of considering these factors in orthodontic treatment planning.

Research and Analysis on Anti-corrosion of Mountain Photovoltaic Brackets

With the increasing global demand for renewable energy,solar photovoltaic power generation technology has been widely applied in China and even globally.Especially in mountainous areas,complex terrain resources are cleverly utilized in the construction of photovoltaic power stations,but this also brings severe challenges to the anti-corrosion of photovoltaic brackets.This paper focuses on the anti-corrosion technology of mountain photovoltaic brackets,and deeply explores the influence of natural factors such as mountain climate,sandstorms,and precipitation on the corrosion of photovoltaic brackets.The research results show that the key to improving anti-corrosion performance lies in the selection of bracket materials and optimization of coating processes.After comparing various anti-corrosion treatment methods such as hot-dip galvanizing,spray aluminum coating,and new anti-corrosion materials,it is found that nano coating technology exhibits excellent protective effects in corrosive environments.This study is of great significance for promoting the sustainable development of photovoltaic power generation,providing solid theoretical support and practical guidance for the anti-corrosion design of mountain photovoltaic power stations.

Design and Optimization of Solar Photovoltaic Brackets in Mountainous Areas Adapted to Complex Wind Environments

With the increasing global demand for renewable energy,the application of photovoltaic power generation in mountainous areas is gradually increasing.However,the complex wind environment in mountainous areas poses severe challenges to the design and optimization of solar photovoltaic brackets.Traditional design methods are difficult to cope with the changeable wind speed and direction in mountainous areas,resulting in structural instability or material waste.Researchers have identified the key factors affecting wind response through parametric research and dynamic wind response analysis,so as to optimize the brackets design and improve its adaptability and stability in complex wind environments.In this paper,the complexity of wind speed,wind direction and turbulence characteristics in mountainous areas and their influence on brackets design are explored.Through static and dynamic wind load analysis,the geometrical shape and material selection of the bracket are optimized to enhance its wind resistance.The application of multi-objective optimization model and intelligent optimization algorithm provides an effective solution for the design of solar photovoltaic brackets,ensuring their safety and reliability in complex wind environments.

Application Strategies of the Bracket Set in Modern Architectural Design

The Bracket Set(dougong)is an important aspect of traditional Chinese architecture known for its exquisite structure,complexity,and rich variations.This design element has been used since the Qin and Han Dynasties and is still prevalent today.It highlights hierarchy and spiritual connotations in the design of a building.This article explores the application of Bracket Set elements in modern architectural design.It analyzes the specific application strategies of this design element,highlighting its value in modern architecture.The goal is to provide modern architectural designers with multiple perspectives and strategies to fully utilize the advantages of Bracket Set elements in architectural design and enhance the artistic value of their work.

高强钢商用车油箱托架热冲压成形工艺研究

为获得具有大弯曲特征的高强钢商用车油箱托架热冲压成形的最佳工艺参数,首先通过有限元模拟分析了摩擦因数、初始温度和成形速度3个成形工艺参数对托架壁厚和最大减薄率的影响。然后,通过正交试验和极差分析法,获得影响零件热冲压成形质量的主次因素和热冲压最佳工艺参数。结果表明,零件最大减薄率随初始温度的升高而降低;随摩擦因数和成形速度的增大而增大。正交试验结果表明,摩擦因数对最大减薄率的影响程度最大,其次是初始温度,成形速度的影响最小。在初始温度为920℃、摩擦因数为0.25、成形速度为30 mm·s^(-1)的参数组合下,零件的最大减薄率为12.3%。试验获得零件的最大减薄率为10.1%,从零件上取样进行拉伸得到抗拉强度均大于1500 MPa,平均硬度达到467.33 HV,显微组织为马氏体和残余奥氏体。试验结果表明有限元模拟的预测误差较小,零件无明显缺陷,并获得了最佳成形工艺参数。

自锁托槽矫治改善患者口腔健康及氧化应激反应的研究

目的探究正畸治疗患者使用自锁托槽矫治对口腔健康状况、龈沟液氧化应激及炎性因子的影响。方法纳入本院正畸治疗共60例患者进行随机分组(2022年4月至2024年4月),依据随机数字表法划分两组各30例。对照组均采取结扎托槽矫治,观察组均采取自锁托槽矫治。基于口腔健康评分、龈沟液氧化应激指标、龈沟液炎性因子水平,分别在治疗前及治疗4周时对其综合评价。结果两组治疗后中文版口腔健康影响程度量表(OHIP-49)得分较治疗前减少(P<0.05);同时观察组OHIP-49得分比对照组更低(P<0.05)。治疗后两组龈沟液丙二醛(MDA)水平和治疗前对比更低,超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GXH-Px)水平和治疗前对比更高(P<0.05);同时观察组MDA比对照组更低,SOD、GXH-Px比对照组更高(P<0.05)。两组治疗后龈沟液前列腺素E_(2)(PGE_(2))、白细胞介素1β(IL-1β)、肿瘤坏死因子-α(TNF-α)水平较治疗前均上升(P<0.05);但观察组上述指标仍比对照组更低(P<0.05)。结论正畸治疗患者使用自锁托槽矫治能调节牙周组织氧化应激反应,减轻炎症反应状态,提升口腔健康水平。

CBCT引导下头颈肩联合腹膜固定方式在乳腺癌IMRT中的临床适用性研究

目的基于锥形束CT(Cone Beam CT,CBCT)影像比较头颈肩联合腹膜体位固定方式和乳腺托架体位固定方式的摆位误差,研究头颈肩联合腹膜在乳腺癌患者调强放射治疗(Intensity Modulated Radiotherapy,IMRT)中体位固定方法的可行性。方法选取需要进行IMRT的40例乳腺癌患者为研究对象,并将其随机分成头颈肩联合腹膜固定组(20例)、乳腺托架固定组(20例)。每例患者在放射治疗(以下简称“放疗”)前行CBCT扫描,每周1次,分析2组患者在X(左右)、Y(进出)、Z(前后)方向的摆位误差、分次间位移和摆位效率。结果头颈肩联合腹膜和托架摆位2组患者在X、Y、Z方向上的摆位误差分别为(1.97±0.94)和(2.11±1.55)mm、(2.54±0.57)和(2.82±1.46)mm、(1.27±0.62)和(2.28±0.96)mm(P=0.801、0.604、0.013);分次间位移分别为(0.76±0.50)和(1.24±0.52)mm、(1.34±0.15)和(2.52±1.18)mm、(0.73±0.33)和(0.88±0.53)mm(P=0.453、0.296、0.773);摆位时间分别为(6.5±1.7)和(8.7±3.1)min(P=0.485);2组X、Y、Z方向上的首次摆位通过率分别为90%和85%、80%和70%、100%和95%(P=0.632、0.464、0.235);分次间摆位通过率为92%和82%、88%和79%、94%和88%(P=0.036、0.086、0.138)。结论头颈肩联合腹膜体位固定方式简单易行,可在一定程度上控制乳腺癌患者IMRT的摆位误差和分次间位移,尤其是Z方向上的摆位误差,提高摆位效率。

铝合金悬置托臂挤压铸造工艺设计与开发

对汽车铝合金悬置托臂进行了挤压铸造浇注系统设计与仿真分析。通过采取增加浇道、局部增压和高压点冷措施改善孤立热节冷却条件,对比改进前后浇注系统对铝合金悬置托臂铸件内部缩孔缺陷的影响;同时研究了不同T6处理工艺对铸件金相组织及力学性能的影响,对同类零件的挤压铸造浇注系统设计及T6处理工艺确定有一定的借鉴意义。

BracKet间接粘着法的临床应用

目的:提高固定矫治器中BracKet的粘接精度,使矫治器发挥最佳矫治疗效。方法:先将BracKet精确地粘接在石膏模型上,后用0.5 mm胶模制做转移模托,将BracKet再转移到模托上。最终将BracKet精确地粘着于牙面上。结果:通过临床观察证明BracKet间接粘着法克服了直接粘着法中BracKet位置不准确,BracKet的粘接高度和角度不易控制的缺点,能使BracKet精确地粘与牙面。结论:随着固定矫治器的不断发展,临床上对BracKet的粘着精度越来越高,为了达到此目标,提高矫治疗效,采用BracKet间接粘着法将托槽的粘着精度大大提高。

海外某光伏项目的光伏组件不同安装方式的技术经济比选

以南美洲某国光照资源丰富区域的233 MWp光伏项目为例,使用PVsyst软件进行发电量仿真计算。先对比1 V与2 V平单轴跟踪支架布置方式,确定1 V竖排布置的平单轴跟踪支架在经济性和发电效率上更优。随后对全部固定支架、全部跟踪支架、固定支架+跟踪支架这3种方案进行综合比较。结果显示,尽管全部跟踪支架方案初期投资较高,但长期发电收益显著优于全部固定支架方案及固定支架+跟踪支架方案。

高精度铅同位素比值MC-ICP-MS测试方法及土壤标准物质铅同位素组成

利用多接收电感耦合等离子体质谱仪(MC-ICP-MS)精准测定了国家土壤标准物质的铅同位素比值,研究了MC-ICP-MS测定铅同位素时的分馏效应,发现仪器存在非质量分馏效应,应用Baxter法和标准与实际样品的交叉组合法(SSB)校正仪器的质量和非质量分馏,校正后NIST SRM 981标准溶液的铅同位素比值具有较高的准确度和精确度。采用MC-ICP-MS测定了3个国家土壤标准物(GBW07564、GBW07406a、GBW07980)的铅同位素比值。对土壤进行微波消解和纯化,回收率大于98%,全流程空白小于0.22 ng。GBW07564铅同位素的^(206)Pb/^(204)Pb为19.9603±0.0303、^(207)Pb/^(204)Pb为15.7675±0.0061、^(208)Pb/^(204)Pb为39.0868±0.0264(n=9,2SD);GBW07406a铅同位素的^(206)Pb/^(204)Pb为18.8024±0.0018、^(207)Pb/^(204)Pb为15.7442±0.0025、^(208)Pb/^(204)Pb为39.1943±0.0086(n=9,2SD);GBW07980铅同位素的^(206)Pb/^(204)Pb为18.6142±0.0057、^(207)Pb/^(204)Pb为15.7378±0.0044、^(208)Pb/^(204)Pb为38.9629±0.0153(n=9,2SD)。这些土壤标准物质的^(206)Pb/^(207)Pb分别为1.2659±0.0014、1.1942±0.0001、1.1828±0.0001(n=9,2SD),^(208)Pb/^(206)Pb分别为1.9582±0.0018、2.0845±0.0003、2.0932±0.0002(n=9,2SD),大致在自然界土壤铅同位素^(206)Pb/^(207)Pb(大于1.17)、^(208)Pb/^(206)Pb(小于2.11)变化范围内,且容易获得,化学和铅同位素组成均一,适合作为监控土壤铅同位素化学及质谱分析数据可靠性的同位素土壤标准物质。

现浇连续梁墩梁式支架施工技术研究

为提升桥梁整体质量,满足煤运重载列车行驶对桥梁稳定性和安全性的要求,以新建蒙西至华中地区铁路煤运通道工程良山大桥为研究对象,围绕其3#~6#墩现浇连续梁墩梁式支架施工进行研究探讨。支架施工是现浇连续箱梁施工的首要内容,在支架拼装后需进行检查验收、预压等操作,以消除非弹性变形,获取弹性变形相关参数,为后续模板安装及钢筋混凝土施工提供技术和安全质量保障,所以必须严格按照设计方案施工,规范支架施工工艺,充分保证支架施工的整体质量。

某变速箱蓄能器支架的有限元分析及优化

蓄能器是高压液压系统的重要组成部分,蓄能器的正常工作是变速箱实现换挡和离合器结合等功能的保证。蓄能器支架是将其固定在壳体上的装置。在某变速箱样件试验中发生了蓄能器支架断裂的问题,导致变速箱相关功能失效,通过排查分析发现为设计原因导致。文章通过有限元法对蓄能器支架进行强度分析,发现在极限工况下蓄能器支架存在断裂失效风险,并基于分析结果对蓄能器支架进行优化设计,最终得到满足要求的设计并顺利通过试验。文中提到的分析方法和优化思路,对蓄能器的设计研发和仿真分析均有一定参考作用。

无托槽隐形矫治在口腔正畸患者中的价值研究

目的探讨无托槽隐形矫治在口腔正畸领域的应用价值。方法选取2022年6月至2023年6月本院收治的120例口腔正畸患者,根据随机数字表法分组,试验组(采用无托槽隐形矫治,60例),对照组(采用传统托槽式矫治,60例)。对比两组的牙周健康状态[龈沟出血指数(SBI)、牙龈指数(GI)、菌斑指数(PLI)、附着丧失水平(CAL)]、龈沟液炎症水平[白细胞介素-1β(IL-1β)、肿瘤坏死因子(TNF-α)、血清前列腺素E2(PGE2)]、患者满意度。结果试验组的SBI、GI、PLI、CAL牙周健康相关指标和IL-1β、TNF-α、PGE2龈沟液炎症水平均低于对照组(P<0.05)。患者满意度比对照组更高(P<0.05)。结论在口腔正畸患者中,无托槽矫治器有助于维护牙周健康,减轻牙周组织的炎症反应,患者满意度较高。

小瑶光特大桥0#块托架预压施工技术研究

连续刚构桥0#块是整个桥梁施工的起始部位,为后续节段的施工提供了基础和支撑,它承担着将桥梁上部结构的荷载传递到桥墩的关键作用。本文以贵州省剑河至黎平高速公路项目为例,以项目小瑶光特大桥0#块三角托架施工为背景,为了模拟0#块施工时托架施工的安全性和确定托架的弹性变形和非弹性变形,确保桥梁线性满足设计要求,采用了反力架预压的施工技术。托架预压按20%→60%→80%→110%逐级加载,分级预压。采用有限元分析与手算结合的方式,分析了满级加载的工况下托架安全性。

基于OptiStruct的轨道车辆天线支架结构轻量化设计

以某轨道车辆天线支架结构为研究对象,运用OptiStruct软件对天线支架结构进行拓扑优化和尺寸优化设计,文章对相关优化流程及结果进行具体的说明及分析。根据EN 12663相关标准对优化后的天线支架结构进行了仿真校核,结果显示强度满足标准要求,新天线支架结构相比于原结构质量减轻68.1%,优化结果理想。文章提出的天线支架结构轻量化方法,达到了降低支架总质量,减少材料使用量,降低生产成本的目的。

销棒支架法在市政桥梁施工中的设计与应用

现浇盖梁支架形式多样,每种支架形式均有其自身特点和适用范围,施工中通常根据工程特点选择不同的支架形式。研究结合工程实际,对其现浇盖梁施工中所采用的销棒法架空支架方案进行介绍,为后续现浇盖梁支架方案在工程中的比选、编制和优化提供参考。

履带自移式快速掘进装备研究

介绍了现有掘锚交替快速掘进装备的现状及其存在的问题,提出了一种新型履带自移式快速掘进装备,详细分析了其组成、工作原理和关键技术等;通过快速掘进装备的合理安排和各设备之间互相紧密配合,达到了工作面割煤连续性、支护连续性、运输连续性的目的,实现了掘进过程的掘锚运平行作业,形成了掘进和支护作业新模式,从根本上缩短了作业时间,提升了掘进效率。

基于增材制造的商用车后处理器支架拓扑优化 设计方法

为探究基于增材制造的拓扑优化设计方法在商用车轻量化领域的应用价值,将商用车后处理器支架作为试验对象,通过拓扑计算、几何重构、打印仿真分析等优化流程,提出了2种材料的优化方案设计,利用选区激光熔化(SLM)工艺完成实物增材制造。最终,2种方案均通过了8000 km强化路台架试验验证,结果表明,基于增材制造的拓扑优化设计方法满足设计及性能要求。