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Seasonally frozen soil effects on the dynamic behavior of highway bridges

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Research in Cold and Arid Regions 2012年第1期4卷 13-20页

作者： ZhaoHui ＂Joey＂ Yang Qiang Li Elmer E. Marx JinChi Lu Department of Civil Engineering University of Alaska-Anchorage Anchorage Alaska USA Bridge Design Engineer State of Alaska DOT＆PF 3132 Channel Drive Juneau AK 99801 USA Assistant Project Scientist Department of Structural Engineering University of California San Diego La Jolla CA 92093 USA

Frozen ground is significantly stiffer than unfrozen ground. For bridges supported on deep foundations, bridge stiffness is also measurably higher in winter months. Significant changes due to seasonal freezing in bridge pier boundary conditions require addi- tional detailing in order to ensure a ductile performance of the bridge during a design earthquake event. This paper reports the lat- est results obtained from a project that systematically investigated the effects of seasonally frozen soil on the seismic behavior of highway bridges in cold regions. A bridge was chosen and was monitored to study its seismic performance and assess the impact of seasonally frozen soil on its dynamic properties. A Finite Element （FE） model was created for this bridge to analyze the impact of seasonal frost. It was found that when frost depth reaches 1.2 m, the first transverse modal frequency increases about 200% when compared with the no-frost case. The results show that seasonal frost has a significant impact on the overall dynamic be- havior of bridges supported by pile foundations in cold regions, and that these effects should be accounted for in seismic design.

关键词： dynamic behavior , seasonally frozen soil pile foundation earthquake Finite Element modeling

Effect of Molecular Weight on Thermoelectric Performance of P3HT Analogues with 2-Propoxyethyl Side Chains

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Journal of Wuhan University of Technology(Materials Science) 2024年第2期39卷 268-281页

作者：董得福 WANG Wei ZHAN Chun LI Chenglong ZHOU Qisheng 肖生强 state Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China

By replacing hexyl chains in poly(3-hexylthiophene)(P3HT)with 2-propoxyethyls,four poly(3-(2-propoxyethyl)thiophene)(P3POET)homopolymers with comparable polydispersity indexes(PDI)and regioregularities were prepared herein in addition with step increment of about 7 kDa on numberaverage molecular weight(M_(n))from around 11 to 32 kDa(accordingly denoted as P11k,P18k,P25k,and P32k).When doped in film by FeCl_(3)at the optimized conditions,the maximum power factor(pf_(max))increases greatly from 4.3μW·m^(-1)·K^(-2)for P11k to 8.8μW·m^(-1)·K^(-2)for P18k,and further to 9.7μW·m^(-1)·K^(-2)for P25k,followed by a slight decrease to 9.2μW·m^(-1)·K^(-2)for *** close Seebeck coefficients(S)at pf_(max)are observed in these doped polymer films due to their consistent frontier orbital energy levels and Fermi *** main contribution to this pf_(max)evolution thus comes from the corresponding conductivities(σ).Theσvariation of the doped films can be rationally correlated with their microstructure evolution.

关键词： conjugated polymer molecular weight microstructure thermoelectric performance

Power Flow Model for Medium-voltage Distribution Systems Considering Measurement and Structure Characteristics

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Journal of Modern Power Systems and Clean Energy 2024年第2期12卷 571-583页

作者： Zhengmei Lu Wei Yan Dezhi Huang Junjie Tang Ferdinanda Ponci Antonello Monti state Key Laboratory of Power Transmission Equipment&System Security and New Technology Chongqing UniversityChongqing 400044China state Grid Zhejiang Yiwu Power Supply Company State Grid Zhejiang Electric Power CompanyYiwu 322001China Institute for Automation of Complex Power Systems of the E.ON Energy Research Center at RWTH Aachen University Aachen52074Germany Digital Energy Fraunhofer FIT Aachen52072Germany IEEE

Medium-voltage distribution systems(MVDSs)mainly consist of a feeder head,lines,distribution transformers,and the equivalent load or power supply interfaced with the distribution *** information of such load or power supply can be measured via the three-wattmeter method(THM)and the two-wattmeter method(TWM).The measurements can be used to perform the control of the power supply and simulate the characteristics of the load,so the models of the load and the power supply need to consider the measurement *** research works on three-phase power flow(pf)just consider the measurement characteristics of ***,the pf equation of the bus measured via TWM is firstly *** on conventional measurements,an accurate and general model of the grounded and ungrounded slack bus is ***,the influence arising from the connection type and angle shift of distribution transformers on the admittance matrix is considered,and thus a general three-phase transformer model is summarized,which is applicable for all the transformers mentioned ***,Newton's method is adopted to solve the pf calculation,and the performance of the proposed pf model is demonstrated through designed tests.

关键词： Medium-voltage distribution system three-phase power flow calculation measurement characteristic slack bus modeling distribution transformer

Effect of micro-dimple patterns on capillary pull-off force and friction force of silicon surface

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Chinese Physics B 2009年第1期18卷 231-237页

作者：张向军董云开刘永合 J.A.Schaefer state Key Laboratory of Tribology Tsinghua University Institute of Physics and Center of Micro/nano Technology Technich University of IlmenauPF 100565Germany

A microtribometer is used to measure and compare pull-off forces and friction forces exerted on （a） micro-dimpled silicon surfaces, （b） bare silicon surfaces, and （c） octadecyltrichlorosilane （OTS） treated silicon surfaces at different relative humidity （RH） levels separately. It is found that above a critical RH level, the capillary pull-off force increases abruptly and that the micro-dimple textured surface has a lower critical RH value as well as a higher pull-off force value than the other two surfaces. A micro topography parameter, namely sidewall area ratio, is found to play a major role in controlling the capillary pull-off force. Furthermore, micro-dimpled silicon surface is also proved to be not sensitive to variation in RH level, and can realize a stable and decreased friction coefficient compared with un-textured silicon surfaces. The reservoir-like function of micro dimples is considered to weaken or avoid the breakage effect of liquid bridges at different RH levels, thereby maintaining a stable frictional behaviour.

关键词： micro-dimpled surface capillary pull-off force frictional property relative humidity

A Least-squares-based Iterative Method with Better Convergence for pf/Opf in Integrated Transmission and Distribution Networks

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CSEE Journal of Power and Energy Systems 2024年第3期10卷 953-962页

作者： Kunjie Tang Shufeng Dong Yonghua Song College of Electrical Engineering Zhejiang UniversityHangzhou 310027China state Key Laboratory of Internet of Things for Smart City and Department of Electrical and Computer Engineering University of MacaoMacao SARChina IEEE

The limitations of the conventional master-slavesplitting(MSS)method,which is commonly applied to power flow and optimal power flow in integrated transmission and distribution(I-T&D)networks,are first *** that the MSS method suffers from a slow convergence rate or even divergence under some circumstances,a least-squares-based iterative(LSI)method is *** with the MSS method,the LSI method modifies the iterative variables in each iteration by solving a least-squares problem with the information in previous iterations.A practical implementation and a parameter tuning strategy for the LSI method are ***,a LSI-pf method is proposed to solve I-T&D power flow and a LSIheterogeneous decomposition(LSI-HGD)method is proposed to solve optimal power *** experiments demonstrate that the proposed LSI-pf and LSI-HGD methods can achieve the same accuracy as the benchmark ***,these LSI methods,with appropriate settings,significantly enhance the convergence and efficiency of conventional ***,in some cases,where conventional methods diverge,these LSI methods can still converge.

关键词： Fixed-point theory integrated transmission and distribution networks least-squares-based iterative method master-slave-splitting method optimal power flow power flow

Tanshinone IIA ameliorates energy metabolism dysfunction of pulmonary fibrosis using 13C metabolic flux analysis

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Journal of Pharmaceutical Analysis 2024年第2期14卷 244-258页

作者： Baixi Shan Haoyan Zhou Congying Guo Xiaolu Liu Mingyu Wu Rao Zhai Jun Chen state Key Laboratory of Natural Medicines China Pharmaceutical UniversityNanjing210009China Department of Pharmacognosy School of Traditional Chinese PharmacyChina Pharmaceutical UniversityNanjing210009China

Evidence indicates that metabolic reprogramming characterized by the changes in cellular metabolic patterns contributes to the pathogenesis of pulmonary fibrosis (pf). It is considered as a promising therapeutic target anti-pf. The well-documented against pf properties of Tanshinone IIA (Tan IIA) have been primarily attributed to its antioxidant and anti-inflammatory potency. Emerging evidence suggests that Tan IIA may target energy metabolism pathways, including glycolysis and tricarboxylic acid (TCA) cycle. However, the detailed and advanced mechanisms underlying the anti-pf activities remain obscure. In this study, we applied [U-13C]-glucose metabolic flux analysis (MFA) to examine metabolism flux disruption and modulation nodes of Tan IIA in pf. We identified that Tan IIA inhibited the glycolysis and TCA flux, thereby suppressing the production of transforming growth factor-β1 (TGF-β1)-dependent extracellular matrix and the differentiation and proliferation of myofibroblasts in vitro. We further revealed that Tan IIA inhibited the expression of key metabolic enzyme hexokinase 2 (HK2) by inhibiting phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR)/hypoxia-inducible factor 1α (HIF-1α) pathway activities, which decreased the accumulation of abnormal metabolites. Notably, we demonstrated that Tan IIA inhibited ATP citrate lyase (ACLY) activity, which reduced the collagen synthesis pathway caused by cytosol citrate consumption. Further, these results were validated in a mouse model of bleomycin-induced pf. This study was novel in exploring the mechanism of the occurrence and development of Tan IIA in treating pf using 13C-MFA technology. It provided a novel understanding of the mechanism of Tan IIA against pf from the perspective of metabolic reprogramming.

关键词： Pulmonary fibrosis Tanshinone IIA 13C-metabolic flux analysis Metabolic reprogramming

Simplified p-i-n Perovskite Solar Cells with a Multifunctional Polyfullerene Electron Transporter

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Chinese Journal of Polymer Science 2024年第8期42卷 1060-1066页

作者： Fei-Fei Wang Tian-Xiao Liu Ze-Wei Cui Ling-Yuan Wang Yun-Jie Dou Xiao-Yu Shi Si-Wei Luo Xiao-Dong Hu Zhi-Jun Ren Yang-Yang Liu Yu Zhao Shang-Shang Chen state Key Laboratory of Coordination Chemistry MOE Key Laboratory of High Performance Polymer Materials&TechnologySchool of Chemistry and Chemical EngineeringNanjing UniversityNanjing 21003China

In prevailing p-i-n perovskite solar cells(PSCs),solution-processible fullerene molecules are widely used as electron-transporting layers(ETLs)but they typically suffer from poor uniformity and undesirable stability ***,a separate bathocuproine(BCP)layer is needed to block hole tran sfer,increasing fabrication complexity and ***,we address these limitations by develo ping a novel polymeric ETL(named pf BCP)synthesized by polymerizing C_(60)with *** innovative material achieves both efficient electron transport and hole blocking,while its excellent uniformity minimizes interface recombination and enhances ***,our blade-coated PSCs utilizing pfBCP achieve a high power conversion efficiency exceeding 22%and retain 91%of initial efficiency after 1200 h of light *** development not only paves the way for commercially viable PSCs but also opens avenues for future ETL design to realize even more efficient and stable PSCs.

关键词： Polyfullerene Perovskite solar cells Electron transporter Stability

Intersection-pavement de-icing: comprehensive review and the state of the practice

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Research in Cold and Arid Regions 2019年第1期11卷 1-12页

作者： ZhaoHui Joey Yang University of alaska Anchorage

Winter maintenance operations are crucial for pedestrian and motorist safety and public mobility on urban streets and highways in cold regions, especially during winter storms. This study provides a comprehensive literature review of existing deicing technologies, with emphasis on electrical resistance-heating deicing technologies for possible applications in areas with concentrated traffic, such as street intersections and crosswalks. A thorough review of existing and emerging deicing technology for snow/ice melting was conducted. The performance of various deicing methods was evaluated and the installation and operation cost of the electrical resistance-heating methods compared. Finally, current state of the practice of intersection/crosswalk winter maintenance was surveyed among state departments of transportation in North America. The intersection/crosswalk winter maintenance procedure adopted by the state of alaska Department of Transportation and Public Facilities was described, and the annual winter maintenance and operation cost per intersection was estimated. It was found that the annual energy cost of an electrical resistance-heating method such as the carbon-fiber-tape deicing technology is about the same as the average annual maintenance and operation cost of current practice. In addition, an automatic electrical resistance-heating deicing system will bring benefits such as minimized delay time and improved safety for pedestrian and vehicular traffic in an urban application.

关键词： deicing technology intersection crosswalk electric resistance heating state of the practice

Controllable and switchable capillary adhesion mechanism for bio-adhesive pads: Effect of micro patterns

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Chinese Science Bulletin 2009年第10期54卷 1648-1654页

作者： ZHANG XiangJun LIU Yuan LIU YongHe AHMED S.I.-U. state Key Laboratory of Tribology Tsinghua University Beijing 100084 China Institute of Physics and Center for Micro/Nano Technology Technical University of IImenau PF 100565 Germany

Some insects and animals, such as bugs, grasshoppers and tree frogs, realize their efficient adhesion mechanism to glass surface, wall and ceiling by injecting a wetting liquid thin film into the pad-substrate contact area. Their ability to control adhesion (attaching or detaching from a surface) is in many cases connected to the contact geometry and surface patterns of their attachment pads. This paper focuses on the dependence of the capillary adhesion (wet adhesion) on the micro patterns of the bio-adhesive pads. The objective is to reveal the possible mechanism for a bio-adhesive pad to control capillary force through adjusting its micro-scale surface pattern and topography. A capillary adhesion force model is built up taking account of the combined role of micro-dimple geometry as well as the wetting behavior of the confined liquid thin film. Calculated results of the apparent contact angle on the regularly micro-dimpled surfaces are compared with and in good agreement with the experimental measurements. Simulation of the capillary adhesion force reveals that it is controllable in a large mag- nitude by adjusting a dimensionless surface pattern parameter k defined as a/(a+b), where a is the dia- meter of micro dimple, and (a+b) is the side length of one pattern cell. When adjusting the parameter k more than 0.75, the capillary adhesion force could be switchable from attractive to repulsive. This effect of micro patterns on the interfacial capillary force is proved to be dominant when the pad-substrate clearance decreases to the nano/micrometer scale. These results indicate that a controllable and switchable capillary adhesive mechanism might be utilized by a living insect or animal to realize its stable adhesion and quick releasing movement through adjusting the micro-pattern topography of its bio-adhesive pad.

关键词：毛细管力可能机制粘合剂粘附生物开关可控玻璃表面