EngRN: Production Engineering (Topic)最新文献

筛选
英文 中文
Impact of information sharing on bullwhip effect in a non-serial supply chain with deterministic lead time 具有确定性提前期的非串行供应链中信息共享对牛鞭效应的影响
EngRN: Production Engineering (Topic) Pub Date : 2021-10-21 DOI: 10.2139/ssrn.3947016
Tamerat Kebede Mekonnen
{"title":"Impact of information sharing on bullwhip effect in a non-serial supply chain with deterministic lead time","authors":"Tamerat Kebede Mekonnen","doi":"10.2139/ssrn.3947016","DOIUrl":"https://doi.org/10.2139/ssrn.3947016","url":null,"abstract":"In this paper, we study the impact of retailers’ forecasting methods on the bullwhip effect. We consider three forecasting methods: Moving average (MA), exponential smoothing (ES), and minimum mean squared error (MMSE). We model retailers’ demand by a first-order autoregressive process. We also assume a base-stock policy for retailers’ stock replenishment. Based on Zhang (2004), we derive expressions for the bullwhip effect for each of the forecasting methods. We considered deterministic as well as stochastic lead time. We also consider multiple independent retailers. Our findings indicate that the impact of demand correlation and lead time on bullwhip effect changes with the forecasting method. However, the patterns seem to remain unaffected by the nature of lead time and the number of retailers. We also observe MMSE to outperform MA and ES when the bullwhip effect is the main concern.","PeriodicalId":325178,"journal":{"name":"EngRN: Production Engineering (Topic)","volume":"19 3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128633189","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Impact of Forecasting Methods on the Bullwhip Effect in a Supply Chain with One Distributor and Multiple Retailers 单分销商多零售商供应链中预测方法对牛鞭效应的影响
EngRN: Production Engineering (Topic) Pub Date : 2021-10-21 DOI: 10.2139/ssrn.3947026
Tamerat Kebede Mekonnen
{"title":"Impact of Forecasting Methods on the Bullwhip Effect in a Supply Chain with One Distributor and Multiple Retailers","authors":"Tamerat Kebede Mekonnen","doi":"10.2139/ssrn.3947026","DOIUrl":"https://doi.org/10.2139/ssrn.3947026","url":null,"abstract":"In this paper, we study the impact of retailers’ forecasting methods on the bullwhip effect. We consider three forecasting methods: Moving average (MA), exponential smoothing (ES), and minimum mean squared error (MMSE). We model retailers’ demand by a first-order autoregressive process. We also assume a base-stock policy for retailers’ stock replenishment. Based on Zhang (2004), we derive expressions for the bullwhip effect for each of the forecasting methods. We considered deterministic as well as stochastic lead time. We also consider multiple independent retailers. Our findings indicate that the impact of demand correlation and lead time on bullwhip effect changes with the forecasting method. However, the patterns seem to remain unaffected by the nature of lead time and the number of retailers. We also observe MMSE to outperform MA and ES when the bullwhip effect is the main concern.","PeriodicalId":325178,"journal":{"name":"EngRN: Production Engineering (Topic)","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133906211","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Optimal Design of Secondary Fume Extraction Systems in Ferroalloys Production: from Principles to Operation 铁合金生产中二次排烟系统的优化设计:从原理到运行
EngRN: Production Engineering (Topic) Pub Date : 2021-09-12 DOI: 10.2139/ssrn.3926016
M. Kadkhodabeigi
{"title":"Optimal Design of Secondary Fume Extraction Systems in Ferroalloys Production: from Principles to Operation","authors":"M. Kadkhodabeigi","doi":"10.2139/ssrn.3926016","DOIUrl":"https://doi.org/10.2139/ssrn.3926016","url":null,"abstract":"In ERAMET Norway AS (ENO) as one of the world’s largest producers of different grades of high manganese alloys, sustainable operation has always been a priority. There are therefore continuous activities in different plants of ENO in order to reduce environmental footprints of our operations. One of the main areas of focus in such activities has been reducing diffuse emissions through design and implementation of efficient fume extraction systems based on a systematic approach. Optimal design of secondary fume extraction systems in ferroalloys industry has always been challenging. The main reason for this, is the diffuse nature of emissions which are generated from different metallurgical processes. Although design of fume capturing systems based on principles of diffuse emissions extraction is the key for high performance capturing of generated fumes from molten slag and metal but there are several operational details, practical aspects and external parameters which should be taken care of them while making an industrial design. These aspects may cause deviation of a design from its ideal conditions because of the need for necessary modifications of the design. In order to make optimal design for secondary fume extraction systems with, having full overview on practical and operational aspects, applying industrial competences, using process information and operational data and applying proper modelling methods to evaluate performance of the system at each st ep, from initial idea to final design, are of great importance. In this work, principles for design of efficient secondary fume extraction systems, main reasons of deviation from best design in the industry and ENO’s practice based on the systematic approach for making an optimal design considering all operational restrictions, is presented.","PeriodicalId":325178,"journal":{"name":"EngRN: Production Engineering (Topic)","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128175423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Effective Binary Diffusivity of Silica and Viscosity of Silicomanganese Slag in the Smelting of Comilog and Wessels Ores Comilog和Wessels矿石冶炼中二氧化硅的有效二元扩散系数和硅锰渣的粘度
EngRN: Production Engineering (Topic) Pub Date : 2021-09-12 DOI: 10.2139/ssrn.3926105
O. Ostrovski
{"title":"Effective Binary Diffusivity of Silica and Viscosity of Silicomanganese Slag in the Smelting of Comilog and Wessels Ores","authors":"O. Ostrovski","doi":"10.2139/ssrn.3926105","DOIUrl":"https://doi.org/10.2139/ssrn.3926105","url":null,"abstract":"Reduction of manganese and silicon oxides in smelting of silicomanganese causes significant changes in slag composition and properties, increasing the slag viscosity and decreasing diffusivities of slag components. These changes can have a strong effect on the kinetics of reduction reactions. This paper analyses effective binary diffusivity of silica and slag viscosity in the process of smelting of silicomanganese from Comilog and Wessels ores. Compositions of slag and metal phases and slag viscosity were calculated using FACTSage Version 7.2 at 1450-1600 oC. Comilog ore contained high concentration of alumina while Wessels ore had lower concentrations of Al2O3 and MnO and higher concentrations of FeO and CaO in comparison with Comilog ore. Silica effective binary diffusivity and slag viscosity were related to the ratio of non-bridging oxygens per tetrahedrally coordinated cations (NBO/T), which decreased in the process of oxides reduction. Changes in the slag composition and NBO/T ratio caused increase in the slag viscosity and decrease in the effective binary diffusivity of silica in the smelting of Comilog ore by more than an order in magnitude. In the smelting of Wessels ore, slag viscosity increased and silica effective binary diffusivity decreased by approximately 5-fold","PeriodicalId":325178,"journal":{"name":"EngRN: Production Engineering (Topic)","volume":"97 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130240525","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
An Experimental Study of the Formation of Surface Agglomerates in a Submerged Arc Furnace 埋弧炉表面结块形成的实验研究
EngRN: Production Engineering (Topic) Pub Date : 2021-09-12 DOI: 10.2139/ssrn.3926630
Ville-Valtteri Visuri, E. Kunelius, E. Puukko, T. Fabritius
{"title":"An Experimental Study of the Formation of Surface Agglomerates in a Submerged Arc Furnace","authors":"Ville-Valtteri Visuri, E. Kunelius, E. Puukko, T. Fabritius","doi":"10.2139/ssrn.3926630","DOIUrl":"https://doi.org/10.2139/ssrn.3926630","url":null,"abstract":"Submerged arc furnace (SAF) is a continuously operating furnace used for ferrochrome production. As the SAF is practically full of feed materials, liquid metal and slag, agglomerates may form in different parts of the furnace. The aim of this work was to set up an experimental apparatus to study the effect of temperature and atmosphere on the formation tendency of agglomerates. The agglomerates formed in the experiments were analyzed using a scanning electron microscope to study their agglomeration mechanism. The results indicate that the main agglomeration mechanisms are sintering and cold welding. Agglomerates formed by sintering exhibited both metallic and oxidic binder phases. The compression strength of the agglomerates was found to exhibit high variance but did exhibit a clear dependence on the agglomeration mechanism.","PeriodicalId":325178,"journal":{"name":"EngRN: Production Engineering (Topic)","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114392994","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Technical Focus on DC-arc Furnace Application to Waste Stream Smelting 直流电弧炉在废液冶炼中的应用技术要点
EngRN: Production Engineering (Topic) Pub Date : 2021-09-12 DOI: 10.2139/ssrn.3927113
S. Louw, B. Belford, A. van Niekerk, R. Degel, M. Reuter
{"title":"Technical Focus on DC-arc Furnace Application to Waste Stream Smelting","authors":"S. Louw, B. Belford, A. van Niekerk, R. Degel, M. Reuter","doi":"10.2139/ssrn.3927113","DOIUrl":"https://doi.org/10.2139/ssrn.3927113","url":null,"abstract":"The application of DC-arc furnaces to the production of commodities such as ferrochrome, ilmenite and smelting of stainless-steel plant waste streams has progressed substantially over the last 30 years. The DC-arc furnace remains a suitable smelting unit for both consumer- & other steel plant waste products and will play a potentially significant role in the development of a circular economy. With increasing environmental legislation requirements and the associated treatment and disposal cost of consumer-, steel plant and smelter waste products, processing of these waste products is increasingly becoming more economically viable, yielding a strong business case and an overall positive environmental impact. The waste products such as spent catalysts, mill scales, steel fines and bag filter dusts often contain valuable elements and various processing routes exist to treat these waste products. The DC-arc furnace is a well-suited furnace application due to its ability to process fine materials and yield products with a higher economical value, without the need of feed-material agglomeration or high-end reductants. Inherently, the process behaviour of these furnaces is dynamic where strict metallurgical process control principles must be applied by the process team to keep the metallurgical condition of the furnace within its operational boundaries. In addition, a number of furnace design aspects further influence the control measures available to the team. This paper will focus on the application of DC-arc furnaces for fine waste stream processing, focussing on a stainless-steel waste sludge case study, with a technical focus on the inherent characteristics and design requirements of these furnaces, required to achieve a stable furnace operation.","PeriodicalId":325178,"journal":{"name":"EngRN: Production Engineering (Topic)","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126812387","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Recycling of Mn-rich ore fines, dust and sludge briquettes in Mn alloys production 锰合金生产中富锰矿粉、粉尘和污泥型块的回收利用
EngRN: Production Engineering (Topic) Pub Date : 2021-09-12 DOI: 10.2139/ssrn.3926126
Laure Diaz, N. Julia, A. Amalric, G. Nussbaum, Kåre Bjarte Bjelland
{"title":"Recycling of Mn-rich ore fines, dust and sludge briquettes in Mn alloys production","authors":"Laure Diaz, N. Julia, A. Amalric, G. Nussbaum, Kåre Bjarte Bjelland","doi":"10.2139/ssrn.3926126","DOIUrl":"https://doi.org/10.2139/ssrn.3926126","url":null,"abstract":"From mining operations to the production of metal alloys, mining and pyrometallurgical industries generate wastes such as sludge and dust. These manganese-rich co-products are currently mostly landfilled. Landfilling has an important impact, both environmentally and economically. ERAMET manganese alloy production plants and other metal industries seek to minimize those effects by recycling such co-products in the Submerged Arc Furnace (SAF). R&D work has been carried out to address this issue through briquetting agglomeration of manganese-rich co-products. These briquettes were used as raw material in the EXCALIBUR (Experimental Campaign of the Limit of Briquette Usage in Recycling) pilot campaign. It aimed at producing High Carbon Ferro Manganese (HCFeMn) in a pilot scale SAF. This study’s main objective is to assess the process stability during briquette recycling. Briquette quality was characterized by measuring fines formation and breakage during transport. Briquette recycling’s impact on the smelting process was quantified by dust generation, furnace stability and overall process performance. These briquette recycling tests in a pilot-scale SAF are part of the feasibility study of this process at an industrial scale.","PeriodicalId":325178,"journal":{"name":"EngRN: Production Engineering (Topic)","volume":"41 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134092631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
Some Carbon-Free Technologies for Manganese Ferroalloy Production 锰铁合金生产中的一些无碳技术
EngRN: Production Engineering (Topic) Pub Date : 2021-09-12 DOI: 10.2139/ssrn.3926069
I. Kero, H. Dalaker, Karen Sende Osen, E. Ringdalen
{"title":"Some Carbon-Free Technologies for Manganese Ferroalloy Production","authors":"I. Kero, H. Dalaker, Karen Sende Osen, E. Ringdalen","doi":"10.2139/ssrn.3926069","DOIUrl":"https://doi.org/10.2139/ssrn.3926069","url":null,"abstract":"To secure a future with the development of solar and wind energy, weather-safe roads and cities around the world, we must be able to produce metals in a safe, climate-neutral and responsible way. Obviously, we must prolong the lifespan of our materials, increase the efficiency of current processes, reuse and recycle what is already available, but that may not be enough. If we are to reach the global development goals, the world will most likely need new materials, including metals. There are many possible technologies that can help cut greenhouse gas emissions from the metallurgical industry, such as biocarbon and hydrogen as reducing agents but also electrolytic and metallothermic reduction routes and combinations of these solutions. Within each of these different themes, there are many technological possibilities. The current article gives an overview of the different alternatives to carbothermic reduction, i.e., describes the solutions which could potentially remove the need for carbon entirely. The discussion focuses on the possibilities, challenges, and the current technological barriers for these technologies to be applied to ferroalloy production.","PeriodicalId":325178,"journal":{"name":"EngRN: Production Engineering (Topic)","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122013639","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Benchmarking of FeNi Electric Arc Furnace Operations for Developing Furnace Design Parameters for Lateritic Ores in the Intermediate SiO2/MgO Range of between 2.2 and 2.7 FeNi电弧炉操作对SiO2/MgO介于2.2 ~ 2.7之间红土矿炉设计参数制定的基准
EngRN: Production Engineering (Topic) Pub Date : 2021-09-12 DOI: 10.2139/ssrn.3926636
P. Palovaara, Sauli Pisila, Matti Sakaranaho, Mikaela Lindvall, J. Tikka
{"title":"Benchmarking of FeNi Electric Arc Furnace Operations for Developing Furnace Design Parameters for Lateritic Ores in the Intermediate SiO2/MgO Range of between 2.2 and 2.7","authors":"P. Palovaara, Sauli Pisila, Matti Sakaranaho, Mikaela Lindvall, J. Tikka","doi":"10.2139/ssrn.3926636","DOIUrl":"https://doi.org/10.2139/ssrn.3926636","url":null,"abstract":"An extensive benchmarking study was conducted to establish the design for a circular 3-electrode electric furnace of 55MW for smelting of nickel saprolitic laterite ores in the intermediate SiO2/MgO range of 2.2-2.7. The investigation was focused on “intermediate slags” in the compositional range of 15-25% FeO, 0-5% Al2O3 and a SiO2/MgO ratio of 2.2-2.7. Industrial furnace references, operating at SiO2/MgO ratios of <2.2 and >2.7, were reviewed as basis for the design. It was found that slag superheats of up to 200°C is needed when producing high grade ferronickel. The bath resistance was estimated to 9-18mOhm and the operational resistance at shielded arc conditions to 35-55mOhm (Parc/Pbath ratios of 2.0-3.0), corresponding to a secondary voltage in the range of 1400-1750V. From the risk mitigation point of view due to slag characteristics, the furnace design was not limited to operation in shielded arc mode solely, but also towards brush arc operation. At the selected hearth power density of ~200 kW/m2 a wide operation window (Parc/Pbath ratio 1.0-2.6) was found manageable to realize freeze lining control at the estimated peak sidewall heat flux of maximum 165kW/m2. A fit for purpose conservative design approach was defined, aligned with industrial references as well as the latest furnace technology developments in intensive copper cooling elements and power stabilization system, which provides a sound basis for the proposed approach.","PeriodicalId":325178,"journal":{"name":"EngRN: Production Engineering (Topic)","volume":"226 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124185679","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Carbide formation and accumulation in SiMn furnaces SiMn炉中碳化物的形成和积累
EngRN: Production Engineering (Topic) Pub Date : 2021-09-12 DOI: 10.2139/ssrn.3926154
Vincent Canaguier, Jonas E Gjøvik, E. Ringdalen
{"title":"Carbide formation and accumulation in SiMn furnaces","authors":"Vincent Canaguier, Jonas E Gjøvik, E. Ringdalen","doi":"10.2139/ssrn.3926154","DOIUrl":"https://doi.org/10.2139/ssrn.3926154","url":null,"abstract":"Recent excavations of Norwegian medium size SiMn furnaces have revealed spectacular amounts of carbide-rich materials accumulating on the sidewalls. In an excavated furnace from Eramet Kvinesdal, producing a 19%Si silicomanganese alloy prior shutdown, the sidewall materials contained silicon carbide in addition to SiMn alloy, slag and carbon. This contrasts with the large amounts of titanium carbides found in a furnace from Ferroglobe (Glencore then) which was producing 16%Si silicomanganese. The significant volume occupied by the carbides is likely to affect the flow of materials as well as furnace operation. It is therefore meaningful to understand how and when those carbides can form, especially concerning titanium carbide given the low content of titanium (about 0.3%) in the raw materials. The present study investigates the conditions under which TiC and SiC can appear in the furnace. Slag, alloy, and gas compositions were chosen to mimic industrial charges and were reacted between 1450 and 1650 °C. The reacted samples were further analysed by electron probe microanalysis with wavelength-dispersive X-ray spectroscopy (EPMA/WDS). Thermodynamic calculations were conducted using FactSage 8.0 and used for further reflection. The results indicate that TiC was formed by both precipitation and chemical reaction.","PeriodicalId":325178,"journal":{"name":"EngRN: Production Engineering (Topic)","volume":"10 33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124732444","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
0
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
提示
您的信息不完整,为了账户安全,请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
确定
请完成安全验证×
相关产品
×
本文献相关产品
联系我们:info@booksci.cn Book学术提供免费学术资源搜索服务,方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。 Copyright © 2023 布克学术 All rights reserved.
京ICP备2023020795号-1
ghs 京公网安备 11010802042870号
Book学术文献互助
Book学术文献互助群
群 号:481959085
Book学术官方微信