Nonlinear Time History Analysis for the Different Column Orientations under Seismic Wave Synthetic Approach

The significant impact of earthquakes on human lives and the built environment underscores the extensive human and economic losses caused by structural collapses. Over the years, researchers have focused on improving seismic design to mitigate earthquake-induced damages and enhance structural performance. In this study, a specific reinforced concrete (RC) frame structure at Kyungpook National University, designed for educational purposes, is analyzed as a representative case. Utilizing SAP 2000, the research conducts a nonlinear time history analysis to assess the structural performance under seismic conditions. The primary objective is to evaluate the influence of different column section designs, while maintaining identical column section areas, on structural behavior. The study employs two distinct seismic waves from Abeno (ABN) and Takatori (TKT) for the analysis, comparing the structural performance under varying seismic conditions. Key aspects examined include displacement, base shear force, base moment, joint radians, and layer displacement angle. This research is anticipated to serve as a valuable reference for seismic restraint reinforcement work on RC buildings, enriching the methods used for evaluating structures through nonlinear time history analysis based on the synthetic seismic wave approach.

Nonlinear Pushover Analysis of the Influences on RC Footing for the External Elevator Well

In contemporary society, reducing carbon dioxide emissions and achieving sustainable development are paramount goals. One effective approach is to preserve existing RC (Reinforced Concrete) buildings rather than demolishing them for new construction. However, a significant challenge arises from the lack of elevator designs in many of these existing RC buildings. Adding an external elevator becomes crucial to solving accessibility issues, enhancing property value, and satisfying modern residential buildings using convenient requirements. However, the structural performance of external elevator wells remains understudied. This research is designed by the actual external elevator project into existing RC buildings in Jinzhong Rd, Shanghai City. Specifically, this research examines five different external elevator wells under nonlinear pushover analysis, each varying in the height of the RC (Reinforced Concrete) footing. By analyzing plastic hinge states, performance points, capacity curves, spectrum curves, layer displacement, and drift ratio, this research aims to provide a comprehensive understanding of how these structures of the external elevator well respond to seismic events. The findings are expected to serve as a valuable reference for future external elevator projects, ensuring the external elevator designs meet the seismic requirements. By emphasizing seismic resistance in the design phase, the research aims to enhance the overall safety and longevity of external elevator systems integrated into existing RC buildings.

Prediction and Analysis of Elevator Traffic Flow under the LSTM Neural Network

Elevators are essential components of contemporary buildings, enabling efficient vertical mobility for occupants. However, the proliferation of tall buildings has exacerbated challenges such as traffic congestion within elevator systems. Many passengers experience dissatisfaction with prolonged wait times, leading to impatience and frustration among building occupants. The widespread adoption of neural networks and deep learning technologies across various fields and industries represents a significant paradigm shift, and unlocking new avenues for innovation and advancement. These cutting-edge technologies offer unprecedented opportunities to address complex challenges and optimize processes in diverse domains. In this study, LSTM (Long Short-Term Memory) network technology is leveraged to analyze elevator traffic flow within a typical office building. By harnessing the predictive capabilities of LSTM, the research aims to contribute to advancements in elevator group control design, ultimately enhancing the functionality and efficiency of vertical transportation systems in built environments. The findings of this research have the potential to reference the development of intelligent elevator management systems, capable of dynamically adapting to fluctuating passenger demand and optimizing elevator usage in real-time. By enhancing the efficiency and functionality of vertical transportation systems, the research contributes to creating more sustainable, accessible, and user-friendly living environments for individuals across diverse demographics.

模糊分割多目标风险框架下电网连锁故障运行风险评估

在分析电网长期演化过程与短期演化过程区别的基础上,提出电网连锁故障运行风险概念,定量分析连锁故障长期风险与运行风险间的关系,建立电网连锁故障运行风险评估模型。利用蒙特卡洛法对给定初始运行方式的电网进行演化模拟,并引入模糊分割多目标风险框架建立评估指标体系。在IEEE 118节点系统中进行算例研究,分析了系统运行参数对给定运行方式下电网连锁故障运行风险的影响。

面向新型电力系统的输电网与分布式变速抽水蓄能联合规划

针对高比例新能源场景下分布式变速抽水蓄能的容量配置及其在电网中的位置接入问题,提出了输电网和分布式变速抽水蓄能的联合规划方案。首先,考虑了各类抽水蓄能的运行和库容约束、火电机组的出力和爬坡约束以及输电网的传输能力,以分布式新能源的经济消纳为优化目标,建立了分布式变速抽水蓄能和输电网间的联合规划模型。然后,通过凸松弛方法将该模型转化为混合整数线性规划模型,以两阶段优化方法求解得到了分布式变速抽水蓄能与输电网的联合规划方案。最后,采用两个标准测试系统对比验证了所提含分布式变速抽水蓄能的联合规划相较于定速抽水蓄能的规划方案,能更好地与其他灵活性资源相协调以消纳风光可再生能源,总体上可降低约20%的成本。

超高压变电站接入弱交流系统的功角、电压稳定问题研究

超高压变电站接入弱交流系统情况不可避免,故障发生后可能引起近区电网暂态稳定问题。系统失稳可能呈现电压失稳和功角失稳两种表现形式,不同运行方式下系统的稳定特征和表现形式不同。在大负荷且地区电源开机不足方式下以电压失稳模式为主导,在小负荷且电源开机较多时以功角失稳模式为主导。部分方式下两种稳定问题相互交织,共同导致系统失稳。以某超高压变电站A接入电网的情况为例,分析了系统存在的稳定问题和相关影响因素,识别了不同运行方式下系统的主导失稳模式,并制定了相应的安全稳定控制措施。

换相失败后直流整流站有功特性及其对送端交流系统影响的研究

针对直流换相失败的研究目前主要集中在逆变站及受端电网,而直流换相失败引起的整流站有功功率变化可能超过直流输电功率,会对送端交流系统造成巨大的功率冲击。首先,介绍了直流换流器的等效数学模型以及目前工程中常用的整流站控制策略。接着,基于包含详细控保系统的实际直流工程电磁暂态仿真模型,结合相关电气量的变化轨迹分析了直流换相失败后整流站注入交流系统的有功功率变化超过正常输送功率的机理,并分析了故障严重程度、功率控制方式、控制器参数等因素对整流侧有功功率冲击大小的影响。最后,针对实际交直流混联电网,分析了受端电网故障引发直流换相失败后,其对送端电网产生的功率冲击对系统稳定性的影响。研究结论可以为实际电网运行提供参考。

呼吸道合胞病毒急性下呼吸道感染门诊患儿临床特征、住院及再发喘息随访研究

目的:研究呼吸道合胞病毒(respiratory syncytial virus,RSV)引起的急性下呼吸道感染门诊患儿临床特征、住院及再发喘息情况。方法:收集2016年10月至2017年3月在重庆医科大学附属儿童医院门诊就诊的2岁以下急性下呼吸道感染(acute lower respiratory infection,ALRI)患儿鼻咽抽吸物,采用PCR方法检测16种常见的呼吸道病毒,对比分析RSV检出患儿的临床特征。分别在入组2周和6个月后对患儿进行住院和再发喘息随访,对导致RSV感染住院和再发喘息危险因素进行logistic回归分析。结果:共收集457例2岁以下的ALRI门诊患儿,400例(87.5%)患儿病毒检出阳性,其中单一RSV检出271例(59.3%),RSV混合其他病毒检出54例(11.8%),其他病毒检75例(16.4%),未检出病毒者57例(12.5%)。与后2组患儿比较,单一RSV检出和RSV混合其他病毒检出组更易出现发热、喘息及呼吸困难症状(均P<0.0083)。单一RSV检出患儿住院者有29例(住院率11.4%),其年龄显著小于未住院患儿(P=0.001)。Logistic分析示年龄(OR=0.766,95%CI=0.649~0.904,P=0.002)是单一RSV检出ALRI患儿住院的保护因素,而早产(OR=5.306,95%CI=1.106~25.459,P=0.037)是其危险因素。对216例6个月随访成功的毛细支气管炎患儿分析后发现,单一RSV检出毛细支气管炎患儿6个月内再发喘息和反复喘息的比例分别是25.9%和15.8%;logistic回归分析发现早产是RSV毛细支气管炎患儿反复喘息发作的危险因素(OR=5.383,95%CI=1.127~25.705,P=0.035)。结论:RSV感染ALRI患儿易出现发热、喘息和呼吸困难。小年龄和早产是RSV相关ALRI患儿住院的危险因素;早产还是RSV感染毛细支气管炎患儿后短期内反复喘息发作的危险因素。

基于皮尔逊相关系数的海南省地闪密度与雷击故障关系分析

海南省属于热带季风气候,雷雨众多,地闪密度远高于平均值,在研究输电线路防雷时需要特别注意地闪密度对雷击故障的影响。文中依据海南省67条35、110、220 k V输电线路资料参数及海南省输电线路近8年的运行报告、事故报告和雷电定位系统的数据绘制了地闪密度图,实际雷击故障分布图,拟合了海南省雷暴日与地闪密度的分布曲线,针对CIGRE经验公式及QGDW 672—2011标准不能准确反映海南省雷电活动的不足,提出了针对海南省地闪密度的分级方法,并基于皮尔逊相关系数分析了CIRGE标准及针对海南省标准下的地闪密度与实际雷击跳闸率的相关性,对海南省的输电线路差异化防雷具有指导意义。

应用支气管镜治疗儿童肺不张407例临床分析

目的:探讨支气管镜在儿童肺不张治疗中的作用。方法:采用回顾性研究方法,选择2014-2015年在重庆医科大学附属儿童医院呼吸中心经胸部X线片或胸部CT检查诊断为肺不张并进行支气管镜检查及灌洗治疗的儿童共407例,对其原发肺部疾病、病原学、肺不张部位等项目进行特征分析,并通过胸部X线片或胸部CT随访复张情况。结果:407例儿童肺不张原发肺部疾病包括肺炎297例(73%)、肺炎合并先天性气道发育异常57例(14%)、支气管扩张伴感染21例(5%)、哮喘急性发作15例(4%)等;除肺炎外,肺炎合并先天性气道发育异常见于<1岁组及1~3岁组,哮喘急性发作常见于>3~6岁组,支气管扩张伴感染常见于>6岁组。最常见的肺不张部位为右肺中叶。常规呼吸道病原检测阳性率61%(247/407),检出病原体依次为细菌(主要为革兰阴性杆菌)、支原体(主要在3岁以上患儿中检出)、病毒(主要在1岁以下患儿中检出)等。灌洗液培养阳性率34%(110/320),灌洗液与鼻咽抽吸物培养检出病原一致性为69%(55/80)。术后失访率43%(177/407),随访复张率90%(206/230)。肺炎、外源性气道异物、哮喘急性发作患儿的复张率较高,肺结核和支气管扩张伴感染患儿的复张率较低,病程越长复张率越低,实施纤维支气管镜手术1次的患儿复张率90%,2次98%,3次及以上复张率逐渐下降。结论:支气管镜在明确儿童肺不张病因及治疗中具有重要作用,可以根据临床情况尽早施行。

Influence of moderate pre-oxidation treatment on the physical, chemical and phosphate adsorption properties of iron-containing activated carbon

A novel adsorbent based on iron oxide dispersed over activated carbon （AC） were prepared, and used for phosphate removal from aqueous solutions. The influence of pre-oxidation treatment on the physical, chemical and phosphate adsorption properties of iron-containing AC were determined. Two series of ACs, non-oxidized and oxidized carbon modified by iron （denoted as AC-Fe and AC/O- Fe）, resulted in a maximum impregnated iron of 4.03% and 7.56%, respectively. AC/O-Fe showed 34.0%46.6% higher phosphate removal efficiency than the AC-Fe did. This was first attributed to the moderate pre-oxidation of raw AC by nitric acid, achieved by dosing Fe（II） after a pre-oxidation, to obtain higher iron loading, which is favorable for phosphate adsorption. Additionally, the in-situ formed active site on the surface of carbon, which was derived from the oxidation of Fe（II） by nitric acid dominated the remarkably high efficiency with respect to the removal of phosphate. The activation energy for adsorption was calculated to be 10.53 and 18.88 kJ/mol for AC-Fe and AC/O- Fe, respectively. The results showed that the surface mass transfer and intra-parficle diffusion were simultaneously occurring during the process and contribute to the adsorption mechanism.

Effect of Na^+ impregnated activated carbon on the adsorption of NH_4^+-N from aqueous solution

Two kinds of activated carbons modified by Na＋ impregnation after pre-treatments involving oxidation by nitric acid or acidification by hydrochloric acid （denoted as AC/N-Na and AC/HCl-Na, respectively）, were used as adsorbents to remove NH4＋-N. The surface features of samples were investigated by BET, SEM, XRD and FT-IR. The adsorption experiments were conducted in equilibrium and kinetic conditions. Influencing factors such as initial solution pH and initial concentration were investigated. A possible mechanism was proposed. Results showed that optimal NH4＋-N removal efficiency was achieved at a neutral pH condition for the modified ACs. The Langmuir isotherm adsorption equation provided a better fit than other models for the equilibrium study. The adsorption kinetics followed both the pseudo second-order kinetics model and intra-particle kinetic model. Chemical surface analysis indicated that Na＋ ions form ionic bonds with available surface functional groups created by pre-treatment, especially oxidation by nitric acid, thus increasing the removal efficiency of the modified ACs for NH4＋-N. Na＋-impregnated ACs had a higher removal capability in removing NH4＋-N than unmodified AC, possibly resulting from higher numbers of surface functional groups and better intra-particle diffusion. The good fit of Langmuir isotherm adsorption to the data indicated the presence of monolayer NH4＋-N adsorption on the active homogenous sites within the adsorbents. The applicability of pseudo second-order and intra-particle kinetic models revealed the complex nature of the adsorption mechanism. The intra-particle diffusion model revealed that the adsorption process consisted not only of surface adsorption but also intra-particle diffusion.