Journal of Zhejiang University-SCIENCE A最新文献

{"title":"Numerical investigations of the failure mechanism evolution of rock-like disc specimens containing unfilled or filled flaws","authors":"Tian-zhen Wang, Jian Wang, Shengke Jiang, Jiahe Zhang","doi":"10.1631/jzus.A2200238","DOIUrl":"https://doi.org/10.1631/jzus.A2200238","url":null,"abstract":"目的 岩石的力学响应和最终破坏模式与破坏机制的演化有关。本文旨在通过光滑粒子流体力学(SPH)方法模拟材料混合破坏行为, 探讨含填充及未填充裂缝的类岩圆盘试件加载后的破坏机制演变。 创新点 1. 在SPH框架中引入混合破坏模型模拟类岩圆盘试样的破坏行为; 2. 通过SPH数值模拟方法分析圆盘试样的破坏机制演化过程, 研究裂纹聚结和裂缝填充的破坏行为。 方法 1. 在SPH框架下, 分别采用张拉损伤模型和Drucker-Prager模型计算材料的张拉破坏和剪切破坏; 模拟一系列巴西圆盘试样的破坏行为并与试验结果对比, 验证所提SPH方法是否可用于模拟岩石的破坏机制演化。2. 通过统计分析, 研究不同裂缝倾角和材料属性联合作用对试样宏观破坏形态及力学响应的影响。 结论 1. 对于含未填充裂缝的圆盘试样, 岩桥区裂纹的聚结机制受裂缝倾角和材料性能的组合影响。2. 对于含填充裂缝的圆盘试件, 当圆盘和填充材料的抗拉强度与粘聚力的比值接近时, 试样的张拉损伤的增长速度更快, 使得整个试件表现更多的脆性特征。3. 随着充填物分布不均匀程度的增加, 试样张拉损伤的增长速率降低, 且圆盘试样展现出更多的延性特征; 当预制裂缝倾角接近45°时, 填充物的影响更大。 The mechanical responses and ultimate failure patterns of rocks are associated with the failure mechanism evolution. In this study, smoothed particle hydrodynamics (SPH) method with the mixed-mode failure model is proposed to probe into failure mechanism evolutions for disc specimens upon loading. The tensile damage model and the Drucker-Prager model are used to calculate the tensile failure and shear failure of the material, respectively. It is concluded that for flaw-unfilled disc specimens, the crack coalescence mechanism in the rock bridge area is affected by the flaw inclination angle and the material property. Considering disc specimens with filled flaws, the incremental rate of tensile damage grows more rapidly when the disc and filling material have a closer ratio of tensile strength to cohesion, which makes the entire specimen response greater brittleness. Furthermore, with the increasing non-uniformity of filling distribution, the incremental rate of tensile-activated damage decreases and the disc specimen performs more ductile. Besides, the influence of the fillings is greater when the flaw inclination angle is approaching 45°. It is proved that the proposed SPH method can be used to simulate the failure mechanism evolution of rocks, which lays a foundation for the study of more complex rock failure.","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"104 1","pages":"64-79"},"PeriodicalIF":3.2,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90578985","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":"Mechanistic investigation on Hg^0 capture over MnO_x adsorbents: effects of the synthesis methods","authors":"Dong Ye, Yongjin Hu, Zhichang Jiang, Xin Liu, Haining Wang","doi":"10.1631/jzus.A2200388","DOIUrl":"https://doi.org/10.1631/jzus.A2200388","url":null,"abstract":"目的 针对当前单质汞高效脱除难题, 本文旨在探讨不同制备方法对锰氧化物吸附剂单质汞捕集性能的影响, 并通过对吸附剂物理化学性质的研究, 揭示锰氧化物吸附剂的构效关系及脱汞机理。 创新点 1. 揭示锰氧化物吸附剂脱汞性能与物化性质之间的构效关系; 2. 阐明锰氧化物吸附剂表面脱汞机理, 并揭示其中的活性位点。 方法 1. 采用常规的沉淀法、水热法及溶胶凝胶法合成锰氧化物吸附剂; 2. 采用微型固定床反应器研究系列锰吸附剂的脱汞性能; 3. 采用物化表征研究系列锰氧化物汞吸附剂的物化特性, 揭示其中的构效关系; 4. 结合动力学计算, 揭示锰氧化物汞吸附剂表面脱汞机理, 并阐明影响吸附剂脱汞性能的关键因素。 结论 1. 与采用沉淀法及水热法制备的汞吸附剂相比, 采用溶胶凝胶法制备的汞吸附剂在150~250 °C的温度区间内具有更为优异的脱汞性能; 2. 采用溶胶凝胶法制备的锰氧化物吸附剂具有丰富的表面酸性位点, 可促进单质汞的吸附, 并为接下来的单质汞氧化步骤提供充足的反应物, 这也是该吸附剂具有优异脱汞性能的主要原因; 3. 脱汞过程中, 初始吸附阶段是主要的速控阶段, 而Mn4+及化学吸附氧为该反应中的主要活性位点。 This study demonstrated the impacts of the synthesis methods on the textural structures, chemical properties, and Hg^0 capture capability of the MnO_ x system. Compared with the samples synthesized using the precipitation (PR) and hydrothermal (HT) methods, the adsorbent prepared via the sol-gel (SG) technique gave the best performance. At 150 °C, ca. 90% Hg^0 removal efficiency was reached after 7.5 h for MnO_ x prepared by the SG method, ca. 40% higher than that of the other two methods. The specific surface area of the adsorbent synthesized via the SG technique (23 m^2/g) was almost double that of the adsorbent prepared by the HT method (12 m^2/g) and three times that of the one prepared by the PR method (7 m^2/g). The presence of plentiful acid sites from the SG method facilitated the physisorption of Hg^0, making more Hg^0 available to be oxidized to HgO by the redox sites and thus giving the adsorbent prepared by the SG method the highest Hg^0 removal efficiency. The strong oxidative ability accelerated the oxidation of the physically adsorbed Hg^0 to HgO, which explained the higher Hg^0 removal efficiency of the sample prepared using the HT method than that of the one synthesized by the PR technique. During the whole Hg^0 removal cycles, chemisorption dominated, with the initial adsorption stage and the external mass-transfer process playing important roles.","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"59 1","pages":"80-90"},"PeriodicalIF":3.2,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83014027","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":"Finite volume method-based numerical simulation method for hydraulic fracture initiation in rock around a perforation","authors":"Yu Zhang, Shaohao Hou, Songhua Mei, Yanan Zhao, Dayong Li","doi":"10.1631/jzus.A2200203","DOIUrl":"https://doi.org/10.1631/jzus.A2200203","url":null,"abstract":"目的 建立射孔围岩水力压裂起裂数值模型, 提出基于有限体积法的射孔围岩水力压裂破裂数值模拟方法, 从而得到流体压力分布和起裂压力等相关参数及其规律。 创新点 1. 运用坐标转换和叠加原理, 推导出考虑孔隙度演化的射孔围岩应力分布; 2. 提出基于有限体积法的射孔围岩水力压裂破裂数值模拟方法。 方法 1. 考虑初始地应力、流体渗流和温度传热对射孔围岩的影响, 运用坐标转换和叠加原理得到射孔围岩应力分布。2. 考虑围岩渗透率和孔隙率的应力敏感性, 采用有限容积法对所提出的方程进行解耦确定射孔围岩的流体压力和温度。3. 在水力压裂射孔围岩破裂准则的基础上, 提出射孔围岩水力压裂破裂数值模拟方法。 结论 1. 随着射孔方位角的上升, 需要更多的注入时间和更高的流体压力才能达到裂缝的起始; 井壁不可渗时的起裂压力更高。2. 当井壁不可渗时, 流体压力在射孔前呈椭圆形分布, 且流体压力从射孔到远处逐渐减少。当井壁是可渗时, 流体压力的分布沿着井筒向外扩散。3. 渗透率和孔隙度的应力敏感性增加了井周区域的流体压力和渗透率, 导致流体流动范围更广, 且起裂压力和时间都有所降低。","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"56 1","pages":"56-63"},"PeriodicalIF":3.2,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88218039","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":"Multiscale multiphysics modeling in geotechnical engineering","authors":"Zhenyu Yin, Qi Zhang, F. Laouafa","doi":"10.1631/jzus.A22MMMiG","DOIUrl":"https://doi.org/10.1631/jzus.A22MMMiG","url":null,"abstract":"在岩土工程领域, 许多应用都涉及到多尺度和多物理场, 例如内部侵蚀、水力压裂、能源桩、城市垃圾处理、非常规油气藏的生产、天然气水合物的热激法和降压法开采、路面的冻融循环、放射性废物处理、污染物运移和二氧化碳封存等等。在文献中, 这些多物理场通常可能包括以下两个或者两个以上方面: 固体变形、流体流动扩散、热传导和热对流、化学/生物反应、电场等等。此外, 所研究的空间尺度可以从纳米级到微米级到数百公里级, 时间尺度也可以从纳秒到数百或数千年不等。近些年来, 受益于计算能力的持续发展和对精密设备制造的大量投资, 数值模拟和多尺度实验室测试已成为地质力学及其相关领域的主流方法。科学家们为了求解多尺度和多物理场过程, 已经开发并成功应用了不同的本构理论、控制方程模型、数值离散方法、求解器等等。为此, 本专题收集在该研究领域具有代表性的研究成果, 涵盖用计算流体动力学和离散元法进行多层土的潜蚀模拟、裂缝变形滞回曲线对二氧化碳吞吐的影响、盐碱岩和石膏岩的溶解、射孔围岩水力压裂的起裂过程这四个方面。我们希望通过本专题, 能帮助读者加强对各个研究领域的理解, 进一步推动多场多尺度问题的应用和发展。","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"34 1","pages":"1-5"},"PeriodicalIF":3.2,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77736930","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":"Modelling and applications of dissolution of rocks in geoengineering","authors":"F. Laouafa, Jianwei Guo, M. Quintard","doi":"10.1631/jzus.A2200169","DOIUrl":"https://doi.org/10.1631/jzus.A2200169","url":null,"abstract":"目的 展示一种用于描述溶解过程及其与岩土工程的耦合的方法, 预测地下洞穴的发育过程, 为天坑等地质灾害的防治提供依据 创新点 用达西尺度模型的扩散界面代替孔隙尺度模型的锐利界面来描述溶解过程, 提升研究对象的尺度和计算效率。 方法 利用体积平均法将孔隙尺度模型上推到达西尺度。 结论 达西尺度模型描述溶解过程与孔隙尺度模型的结果吻合良好, 可广泛应用于岩土工程中的各类溶解问题。 The subsoil contains many evaporites such as limestone, gypsum, and salt. Such rocks are very sensitive to water. The deposit of evaporites raises questions because of their dissolution with time and the mechanical-geotechnical impact on the neighboring zone. Depending on the configuration of the site and the location of the rocks, the dissolution can lead to surface subsidence and, for instance, the formation of sinkholes and landslides. In this study, we present an approach that describes the dissolution process and its coupling with geotechnical engineering. In the first part we set the physico-mathematical framework, the hypothesis, and the limitations in which the dissolution process is stated. The physical interface between the fluid and the rock (porous) is represented by a diffuse interface of finite thickness. We briefly describe, in the framework of porous media, the steps needed to upscale the microscopic-scale (pore-scale) model to the macroscopic scale (Darcy scale). Although the constructed method has a large range of application, we will restrict it to saline and gypsum rocks. The second part is mainly devoted to the geotechnical consequences of the dissolution of gypsum material. We then analyze the effect of dissolution in the vicinity of a soil dam or slope and the partial dissolution of a gypsum pillar by a thin layer of water. These theoretical examples show the relevance and the potential of the approach in the general framework of geoengineering problems.","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"111 1","pages":"20-36"},"PeriodicalIF":3.2,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76775411","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":"Biophysical neurons, energy, and synapse controllability: a review","authors":"Jun Ma","doi":"10.1631/jzus.A2200469","DOIUrl":"https://doi.org/10.1631/jzus.A2200469","url":null,"abstract":"目的 阐明功能性神经元设计的物理机理, 揭示能量调控神经元放电模态和突触活性的物理机理, 并论证神经元自适 应性选频的路径和神经元网络内异质性和缺陷的形成。 创新点 1. 建立了包含表达电磁感应、热效应和温度感知、光敏、压电感知和磁场感知的系列神经元模型; 2. 定义了 神经元中哈密顿能量并解释其来源和计算方法; 3. 指出哈密顿能量对神经元突触调控的物理机理和方法; 4. 解 释了听觉神经元和视觉神经元在外界刺激下的选频响应机理; 5. 解释了神经元网络内异质性和缺陷形成的能 量机理。 方法 把忆阻器、热敏电阻、光电管、压电陶瓷、约瑟夫森结等嵌入简单的电感-电容和电阻耦合的神经元电路, 实 现对外界物理信号的捕获和感知。从神经元电路场能量方程和赫姆霍兹定理分别得出功能神经元模型的能量函 数, 确认其表达式的唯一性和一致性。以神经元能量函数为控制开关, 对神经元突触进行自适应控制来实现能 量平衡。 结论 1. 特定物理器件嵌入神经元电路可以增强其物理感知能力; 2. 能量驱动和调控可以有效控制神经元和神经元 网络放电模态和时空斑图; 3. 生物神经元的多重自适应性源于能量流的平衡分配。 Diffusive intracellular and extracellular ions induce a gradient electromagnetic field that regulates membrane potential, and energy injection from external stimuli breaks the energy balance between the magnetic and electric fields in a cell. Indeed, any activation of biophysical function and self-adaption of biological neurons may be dependent on energy flow, and synapse connection is controlled to reach energy balance between neurons. When more neurons are clustered and gathered closely, field energy is exchanged and shape formation is induced to achieve local energy balance. As a result, the coexistence of multiple firing modes in neural activities is fostered to prevent the occurrence of bursting synchronization and seizure. In this review, a variety of biophysical neuron models are presented and explained in terms of their physical aspects, and the controllability of functional synapses, formation of heterogeneity, and defects are clarified for knowing the synchronization stability and cooperation between functional regions. These models and findings are summarized to provide new insights into nonlinear physics and computational neuroscience.","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"1 1","pages":"109-129"},"PeriodicalIF":3.2,"publicationDate":"2022-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90214666","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 hydraulic fracture deformation hysteresis on CO_2 huff-n-puff performance in shale gas reservoirs","authors":"Xia Yan, Piyang Liu, Zhao-qin Huang, Hai Sun, Kai Zhang, Jun-feng Wang, Jun Yao","doi":"10.1631/jzus.A2200142","DOIUrl":"https://doi.org/10.1631/jzus.A2200142","url":null,"abstract":"目的 在页岩气藏CO_2吞吐过程中, 水力裂缝处于循环载荷作用下时, 极易发生不可逆变形(变形滞后), 影响吞吐效果。本文旨在建立考虑水力裂缝变形滞后的页岩气藏CO_2吞吐流固耦合模型, 形成相应的高效求解方法, 并开展流固耦合数值模拟研究, 以揭示变形滞后对CO_2吞吐的影响规律。 创新点 1. 建立考虑水力裂缝变形滞后、复杂裂缝系统和特殊流动机理的页岩气藏多组分流固耦合模型, 并形成相应的三维高效数值模拟技术; 2. 揭示水力裂缝变形滞后对页岩气藏CO_2吞吐的影响规律。 方法 1. 建立考虑水力裂缝变形滞后、复杂裂缝系统和特殊流动机理的页岩气藏多组分流固耦合模型; 2. 基于结构化网格构造高效稳定的多组分流固耦合模型数值求解算法; 3. 通过流固耦合数值模拟, 揭示水力裂缝变形滞后对页岩气藏CO_2吞吐的影响规律。 结论 1. 水力裂缝变形滞后会阻碍 CO_2注入期间裂缝渗透率的恢复, 对CO_2吞吐有负面影响; 2. 较低的初始水力裂缝导流能力和生产压力、较晚的吞吐启动时间、较高的注入压力和较多的循环次数均会增强变形滞后的负面影响; 3. CO_2吞吐效果与初始水力裂缝导流能力、吞吐启动时间、注入压力和循环次数呈正相关, 与生产压力呈负相关。 As a promising enhanced gas recovery technique, CO_2 huff-n-puff has attracted great attention recently. However, hydraulic fracture deformation hysteresis is rarely considered, and its effect on CO_2 huff-n-puff performance is not well understood. In this study, we present a fully coupled multi-component flow and geomechanics model for simulating CO_2 huff-n-puff in shale gas reservoirs considering hydraulic fracture deformation hysteresis. Specifically, a shale gas reservoir after hydraulic fracturing is modeled using an efficient hybrid model incorporating an embedded discrete fracture model (EDFM), multiple porosity model, and single porosity model. In flow equations, Fick’s law, extended Langmuir isotherms, and the Peng-Robinson equation of state are used to describe the molecular diffusion, multi-component adsorption, and gas properties, respectively. In relation to geomechanics, a path-dependent constitutive law is applied for the hydraulic fracture deformation hysteresis. The finite volume method (FVM) and the stabilized extended finite element method (XFEM) are applied to discretize the flow and geomechanics equations, respectively. We then solve the coupled model using the fixed-stress split iterative method. Finally, we verify the presented method using several numerical examples, and apply it to investigate the effect of hydraulic fracture deformation hysteresis on CO_2 huff-n-puff performance in a 3D shale gas reservoir. Numerical results show that hydraulic fracture deformation hysteresis has some negative effects on CO_2 huff-n-puff performance. The effects are sensitive to the initial conductivity of hydraulic fracture, production pressure, starting time of huff-n-puff, injection pressure, and huff-n-puff cycle number.","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"22 1","pages":"37-55"},"PeriodicalIF":3.2,"publicationDate":"2022-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77049321","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":"Optimum insulation thickness of external walls by integrating indoor moisture buffering effect: a case study in the hot-summer-cold-winter zone of China","authors":"Yan Feng, Zitao Yu, Jiang Lu, Xu Xu","doi":"10.1631/2023.A2200158","DOIUrl":"https://doi.org/10.1631/2023.A2200158","url":null,"abstract":"In the high-humidity, hot-summer-cold-winter (HSCW) zone of China, the moisture buffering effect in the envelope is found to be significant in optimum insulation thickness. However, few studies have considered the effects of indoor moisture buffering on the optimum insulation thickness and energy consumption. In this study, we considered the energy load of an exterior wall under moisture transfer from the outdoor to the indoor environment. An optimum insulation thickness was obtained by integrating the P1−P2 model. A residential building was selected for the case study to verify the proposed method. Finally, a comparison was made with two other widely used methods, namely the transient heat transfer model (TH) and the coupled heat and moisture transfer model (CHM). The results indicated that the indoor moisture buffering effect on the optimum insulation thickness is 2.54 times greater than the moisture buffering effect in the envelope, and the two moisture buffering effects make opposing contributions to the optimum insulation thickness. Therefore, when TH or CHM was used without considering the indoor moisture buffering effect, the optimum insulation thickness of the southern wall under one air change per hour (1 ACH) and 100% normal heat source may be overestimated by 2.13% to 3. 59%, and the annual energy load on a single wall may be underestimated by 10.10% to 11.44%. The decrease of airtightness and the increase of indoor heat sources may result in a slight reduction of optimum insulation thickness. This study will enable professionals to consider the effects of moisture buffering on the design of insulation thickness.","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"104 1","pages":"998 - 1012"},"PeriodicalIF":3.2,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76862344","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":"Hole-growth phenomenon during pyrolysis of a cation-exchange resin particle","authors":"Zhengliang Huang, Yun-bo Yu, Qiuyue Song, Yao Yang, Jingyuan Sun, Jingdai Wang, Yong-rong Yang","doi":"10.1631/2023.A2200233","DOIUrl":"https://doi.org/10.1631/2023.A2200233","url":null,"abstract":"A novel central hole-expansion phenomenon is identified, in which the cation-exchange resin is pyrolyzed in a mixed atmosphere of nitrogen and oxygen at 400–500 °C. In this reaction, the reaction path is predictable and always starts from the center of the resin particle to form a central hole, then continues and expands around the hole, finally forming a uniformly distributed hole group; the particle surface remains intact. Analysis shows that this formation mode is due to the different reaction paths of sulfonic groups between the surface and interior of the particle, caused by the temperature difference. On the surface, transformation reactions happen at high temperatures (410–500 °C) to form stable organic sulfur structures, while decomposition occurs inside the particle at a relatively low temperature (<410 °C) and promotes complete pyrolysis of the copolymer matrix to form holes.","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"43 1","pages":"974 - 987"},"PeriodicalIF":3.2,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73681787","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":"Investigations on lubrication characteristics of high-speed electric multiple unit gearbox by oil volume adjusting device","authors":"Shuai Shao, Kailin Zhang, Yuan Yao, Yi Liu, Jun Gu","doi":"10.1631/2023.A2200274","DOIUrl":"https://doi.org/10.1631/2023.A2200274","url":null,"abstract":"In this paper, a numerical simulation model of the flow field in a gearbox with an oil volume adjusting device is established for the first time to study its influence on the lubrication characteristics of a high-speed electric multiple unit (EMU) gearbox. The moving particle semi-implicit (MPS) method is used to numerically simulate the internal flow field of the gearbox of the high-speed EMU under working conditions. The effects of the velocity of the high-speed EMU, the immersion depth, and the oil sump temperature on the power loss of the gears and the lubricant quantity of each bearing are studied and provide an effective tool for the quantitative evaluation of the lubrication characteristics of the gearbox. The lubrication characteristics of the gearbox under different working conditions are studied when the oil volume adjusting device is closed and opened. The results show that the oil volume adjusting device mainly changes the amount of lubricant stirred by the output gear by changing the flow rate of lubricant from the cavity pinion (Cavity P) to the cavity gear (Cavity G), and thus affects the power loss of gears and the lubricant quantity of each bearing.","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"21 1","pages":"1013 - 1026"},"PeriodicalIF":3.2,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81822843","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}