Journal of Zhejiang University-SCIENCE A最新文献

{"title":"上覆土层岩石锚墩基础单调上拔承载特性研究","authors":"Yizhou Sun, Honglei Sun, Chong Tang, Yu Cai, Feng Pan","doi":"10.1631/jzus.a2200446","DOIUrl":"https://doi.org/10.1631/jzus.a2200446","url":null,"abstract":"","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"43 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78452274","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fractal analysis of small-micro pores and estimation of permeability of loess using mercury intrusion porosimetry","authors":"Tuo Lu, Yaming Tang, Y. Tie, B. Hong, Wu-chun Feng","doi":"10.1631/jzus.A2200528","DOIUrl":"https://doi.org/10.1631/jzus.A2200528","url":null,"abstract":"Many popular models have been proposed to study the fractal properties of the pores of porous materials based on mercury intrusion porosimetry (MIP). However, most of these models do not directly apply to the small-micro pores of loess, which have a significant impact on the throat pores and tunnels for fluid flow. Therefore, in this study we used a combination of techniques, including routine physical examination, MIP analysis, and scanning electron microscope (SEM) image analysis, to study these small-micro pores and their saturated water permeability properties. The techniques were used to determine whether the fractal dimensions of six MIP fractal models could be used to evaluate the microstructure types and permeability properties of loess. The results showed that the Neimark model is suitable for analysis of small-micro pores. When applied to saturated water permeability, the results from this model satisfied the correlation significance test and were consistent with those from SEM analysis. A high clay content and density cause an increase in the number of small-micro pores, leading to more roughness and heterogeneity of the pore structure, and an increase in the fractal dimensions. This process further leads to a decrease in the content of macro-meso pores and saturated water permeability. Furthermore, we propose new parameters: the *Ellipse and its area ratios (*EAR). These parameters, coupled with 2D-SEM and 3D-MIP fractal dimensions, can effectively and quantitatively be used to evaluate the types of loess microstructures (from type I to type III) and the saturated water permeability (magnitude from 1×10−4 cm/s to 1×10−5 cm/s).","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"93 1","pages":"584 - 595"},"PeriodicalIF":3.2,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89084473","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Correlation between travel experiences and post-COVID outbound tourism intention: a case study from China","authors":"Yilin Sun, Yinan Dong, Dianhai Wang, E. Waygood, Hamed Naseri, K. Nishii","doi":"10.1631/jzus.a2300057","DOIUrl":"https://doi.org/10.1631/jzus.a2300057","url":null,"abstract":"","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"38 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2023-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81211351","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analytical solution of ground-borne vibration due to a spatially periodic harmonic moving load in a tunnel embedded in layered soil","authors":"Lihui Xu, Menglu Ma","doi":"10.1631/jzus.A2200385","DOIUrl":"https://doi.org/10.1631/jzus.A2200385","url":null,"abstract":"目的 地铁列车运行时诱发的振动会对周围环境造成不利影响。本文旨在提出适用于振动预测的周期性隧道-地层耦合解析模型, 探讨各种参数(地层参数、隧道参数、荷载参数等)对振动响应的影响, 研究振动的传播规律, 为减振设计提供理论依据。 创新点 1. 根据平面波与柱面波之间的转换关系, 推导适用于环境振动预测的周期性隧道-地层耦合解析模型; 2. 通过参数分析, 明确移动周期简谐荷载下振动响应的规律及各种参数的影响。 方法 1. 通过理论推导和考虑隧道结构与层状土间的动力相互作用, 获得移动周期简谐荷载下动力响应的计算方法(公式(19)); 2. 通过对比验证, 以及根据现有移动常力及移动简谐荷载的动力响应结果, 验证所提模型的准确性及高效性(图4~6); 3. 通过参数分析, 设置工程常见的参数(地层参数、隧道参数和荷载参数等), 得到移动周期简谐荷载下的振动响应规律及各种参数的影响(图7~16)。 结论 1. 所提周期性隧道-地层耦合解析模型的计算效率高, 预测结果准确, 可用于地铁列车振动环境影响预测。2. 由于荷载移动效应及多普勒效应, 荷载参数影响振动响应主频及频率分布带宽, 但地层参数及隧道参数的影响较小。3. 增加隧道埋深是降低地表振动水平的有效措施。4. 地表一定距离处的振动水平高于隧道正上方, 即出现振动放大区; 环评时应当重点关注放大区内的振动水平, 避免不利影响。 In this study, we propose a novel coupled periodic tunnel–soil analytical model for predicting ground-borne vibrations caused by vibration sources in tunnels. The problem of a multilayered soil overlying a semi-infinite half-space was solved using the transfer matrix method. To account for the interactions between the soil layer and tunnel structure, the transformation characteristics between cylindrical waves and plane waves were considered and used to convert the corresponding wave potentials into forms in terms of the Cartesian or cylindrical coordinate system. The induced ground-borne vibration was obtained analytically by applying a spatially periodic harmonic moving load to the tunnel invert. The accuracy and efficiency of the proposed model were verified by comparing the results under a moving constant and harmonic load with those from previous studies. Subsequently, the response characteristics under a spatially periodic harmonic moving load were identified, and the effects of a wide range of factors on the responses were systematically investigated. The numerical results showed that moving and Doppler effects can be caused by a spatially periodic harmonic moving load. The critical frequency and frequency bandwidth of the response are affected by the load type, frequency, velocity, and wavenumber in one periodicity length. Increasing the tunnel depth is an efficient way to reduce ground-borne vibrations. The effect of vibration amplification on the free surface should be considered to avoid excessive vibration levels that disturb residents.","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"23 1","pages":"637-652"},"PeriodicalIF":3.2,"publicationDate":"2023-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81745735","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of coral sand on the mechanical properties and hydration mechanism of magnesium potassium phosphate cement mortar","authors":"Hao Liu, Huamei Yang, Houzhen Wei, Jining Yu, Q. Meng, Rongtao Yan","doi":"10.1631/jzus.a2200389","DOIUrl":"https://doi.org/10.1631/jzus.a2200389","url":null,"abstract":"","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"27 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2023-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91092861","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Two-stage identification of interlayer contact loss for CRTS III prefabricated slab track based on multi-index fusion","authors":"W. Du, J. Ren, Kaiyao Zhang, Shijie Deng, Shuyi Zhang","doi":"10.1631/jzus.A2300010","DOIUrl":"https://doi.org/10.1631/jzus.A2300010","url":null,"abstract":"To accurately identify the potential contact loss of the China railway track system (CRTS) III prefabricated slab track, a finite element model with contact loss of self-compacting concrete (SCC) under transient impact was established. Then the vertical accelerations near impact points on the track slab surface were extracted to obtain damage-sensitive indices in the time and frequency domains. The indices were initially normalized to obtain independent items of evidence before the Dempster-Shafer (D-S) evidence theory was used to fuse these into one. Finally, a two-stage identification was performed to identify the damaged SCC area, comprising a rough identification (Stage I) and a precise identification (Stage II). The research results show that the damage indices extracted based on the transient impact response change abruptly at the damage location, and that can be used for damage identification. However, the use of a single index to determine the damage of the impact point may be misjudged. In Stage I, five damage indices of acceleration were fused to magnify the difference between the damaged point and undamaged point, thereby improving the accuracy of finding damage. In Stage II, in the area where more impact points were added, a fusion of three indices of acceleration response, that is, the absolute mean of the time domain, the maximum amplitude of the frequency domain, and the power density ratio, further narrowed down the area where damage exists. As a result, when the contact loss of SCC is greater than 50% along the thickness direction, the identification accuracy can be as high as 70% to 80%. The two-stage identification method proposed in this study can greatly improve the efficiency of interlayer damage detection of slab tracks and is expected to provide effective technical support for damage identification of track structures in the future.","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"22 1","pages":"497 - 515"},"PeriodicalIF":3.2,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75395943","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of additional cylinders on power-extraction performance of a Savonius vertical-axis wind turbine","authors":"Yangyang Yan, Jintao Zhang, Junao She, Wenhao Liu, Jianghong Deng, Jianyang Zhu","doi":"10.1631/jzus.A2200292","DOIUrl":"https://doi.org/10.1631/jzus.A2200292","url":null,"abstract":"To improve the power-extraction performance of the Savonius vertical-axis wind turbine (S-VAWT), additional cylinders, which are used to control the fluid flow around the wind turbine blade, were introduced into the blade design. In contrast to the traditional numerical method, a mathematical model in the form of a dynamical system was used in this study. A numerical calculation program that could effectively solve the equations of wind-induced rotation of S-VAWT was developed, and combined with the Taguchi experimental method to investigate the influence of additional cylinders on the power-extraction characteristics of the S-VAWT. The results showed that the additional cylinders have a significant impact on the power-extraction performance of the S-VAWT. At 4-m/s wind speed, the average power coefficient of the S-VAWT with additional cylinders is 15% higher than that of the conventional S-VAWT. After construction of the wind turbine prototype and power-extraction tests, the results showed that compared with a conventional S-VAWT, the output power was 29% higher for the S-VAWT with additional cylinders under the same particular conditions.","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"18 1","pages":"531 - 542"},"PeriodicalIF":3.2,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76579623","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"基于质心动态规划的四足机器人稳定运动控制策略","authors":"Yangyang Han, Guoping Liu, Zhenyu Lu, Huaizhi Zong, Junhui Zhang, Feifei Zhong, Liyu Gao","doi":"10.1631/jzus.a2200310","DOIUrl":"https://doi.org/10.1631/jzus.a2200310","url":null,"abstract":"","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"8 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83488486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical modeling and experimental study of microstamping process for fabricating microchannels using thin sheets of titanium","authors":"WenZe Mao, Yan-cheng Wang, Deqing Mei, Ling Xuan, Caiying Zhou","doi":"10.1631/jzus.a2300083","DOIUrl":"https://doi.org/10.1631/jzus.a2300083","url":null,"abstract":"","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"73 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83722810","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation of flow characteristics in a rotor-stator cavity under crossflow using wall-modelled large-eddy simulation","authors":"Lei Xie, Qian Du, Guang Liu, Zengyan Lian, Yaguang Xie, Yifu Luo","doi":"10.1631/jzus.A2200565","DOIUrl":"https://doi.org/10.1631/jzus.A2200565","url":null,"abstract":"Rotor-stator cavities are frequently encountered in engineering applications such as gas turbine engines. They are usually subject to an external hot mainstream crossflow which in general is highly swirled under the effect of the nozzle guide vanes. To avoid hot mainstream gas ingress, the cavity is usually purged by a stream of sealing flow. The interactions between the external crossflow, cavity flow, and sealing flow are complicated and involve all scales of turbulent unsteadiness and flow instability which are beyond the resolution of the Reynolds-average approach. To cope with such a complex issue, a wall-modeled large-eddy simulation (WMLES) approach is adopted in this study. In the simulation, a 20° sector model is used and subjected to a uniform pre-swirled external crossflow and a stream of radial sealing flow. It is triggered by a convergent Reynolds-averaged Navier-Stokes (RANS) result in which the shear stress transport (SST) turbulent model is used. In the WMLES simulation, the Smagoringsky sub-grid scale (SGS) model is applied. A scalar transportation equation is solved to simulate the blending and transportation process in the cavity. The overall flow field characteristics and deviation between RANS and WMLES results are discussed first. Both RANS and WMLES results show a Batchelor flow mode, while distinct deviation is also observed. Deviations in the small-radius region are caused by the insufficiency of the RANS approach in capturing the small-scale vortex structures in the boundary layer while deviations in the large-radius region are caused by the insufficiency of the RANS approach in predicting the external crossflow ingestion. The boundary layer vortex and external ingestion are then discussed in detail, highlighting the related flow instabilities. Finally, the large-flow structures induced by external flow ingress are analyzed using unsteady pressure oscillation signals.","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"33 1","pages":"473 - 496"},"PeriodicalIF":3.2,"publicationDate":"2023-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82556327","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}