Short process forming techniques for brazing and soldering materials can shorten the process,improve product quality,and increase production efficiency,which has received much attention from welding researchers.This r...Short process forming techniques for brazing and soldering materials can shorten the process,improve product quality,and increase production efficiency,which has received much attention from welding researchers.This review mainly summarized the research reports on short process forming techniques for brazing and soldering materials.Firstly,the traditional process and its shortcomings were presented.Secondly,the latest research of short process forming technologies,such as continuous casting technique,atomization powder technique,solder ball forming technique,and rapid solidification technique,was summarized,and the traditional forming performance of several brazing and soldering materials was introduced.Finally,the current restrictions and research trends of short process forming technique for brazing and solder materials were put forward,providing theoretical guidance and reference for related research and technique development in brazing and soldering field.展开更多
Al-Mg-Si(AA6xxx)series alloys have been used widely in automotive industry for lightweight purpose.This work focuses on developing a short process for manufacturing Al-0.5Mg-1.3Si(wt.%)alloy sheets with good mechanica...Al-Mg-Si(AA6xxx)series alloys have been used widely in automotive industry for lightweight purpose.This work focuses on developing a short process for manufacturing Al-0.5Mg-1.3Si(wt.%)alloy sheets with good mechanical properties.Hereinto,a preparation route without homogenization was proposed on the basis of sub-rapid solidification(SRS)technique.The sample under SRS has fine microstructure and higher average partition coefficients of solute atoms,leading to weaker microsegregation owing to the higher cooling rate(160℃/s)than conventional solidification(CS,30℃/s).Besides,Mg atoms tend to be trapped in Al matrix under SRS,inducing suppression of Mg2Si,and promoting generation of Al Fe Si phase.After being solution heat treated(T4 state),samples following the SRS route have lower yield strength compared with that by CS route,indicating better formability in SRS sample.After undergoing pre-strain and artificial aging(T6 state),the SRS samples have comparable yield strength to CS samples,satisfying the service requirements.This work provides technological support to industrially manufacture high performance AA6xxx series alloys with competitive advantage by a novel,short and low-cost process,and open a door for the further development of twin-roll casting based on SRS technique in industries.展开更多
As an important intermediate product, short-chain fatty acids（SCFAs） can be generated after hydrolysis and acidification from waste activated sludge, and then can be transformed to methane during anaerobic digestion...As an important intermediate product, short-chain fatty acids（SCFAs） can be generated after hydrolysis and acidification from waste activated sludge, and then can be transformed to methane during anaerobic digestion process. In order to obtain more SCFA and methane,most studies in literatures were centered on enhancing the hydrolysis of sludge anaerobic digestion which was proved as un-efficient. Though the alkaline pretreatment in our previous study increased both the hydrolysis and acidification processes, it had a vast chemical cost which was considered uneconomical. In this paper, a low energy consumption pretreatment method, i.e. enhanced the whole three stages of the anaerobic fermentation processes at the same time, was reported, by which hydrolysis and acidification were both enhanced, and the SCFA and methane generation can be significantly improved with a small quantity of chemical input. Firstly, the effect of different pretreated temperatures and pretreatment time on sludge hydrolyzation was compared. It was found that sludge pretreated at 100°C for 60 min can achieve the maximal hydrolyzation. Further, effects of different initial p Hs on acidification of the thermal pretreated sludge were investigated and the highest SCFA was observed at initial p H 9.0with fermentation time of 6 d, the production of which was 348.63 mg COD/g VSS（6.8 times higher than the blank test） and the acetic acid was dominant acid. Then, the mechanisms for this new pretreatment significantly improving SCFA production were discussed. Finally,the effect of this low energy consumption pretreatment on methane generation was investigated.展开更多
In several stress responsive gene loci of monocot cereal crops,we have previously identified an unusual posttranscriptional processing mediated by paired presence of short direct repeated （SDR） sequences at 5＇ and ...In several stress responsive gene loci of monocot cereal crops,we have previously identified an unusual posttranscriptional processing mediated by paired presence of short direct repeated （SDR） sequences at 5＇ and 3＇ splicing junctions that are distinct from conventional （U2/U12-type） splicing boundaries.By using the known SDR-containing sequences as probes,24 plant candidate genes involved in diverse functional pathways from both monocots and dicots that potentially possess SDR-mediated posttranscriptional processing were predicted in the GenBank database.The SDRs-mediated posttranscriptional processing events including cis-and trans-actions were experimentally detected in majority of the predicted candidates.Extensive sequence analysis demonstrates several types of SDR-associated splicing peculiarities including partial exon deletion,exon fragment repetition,exon fragment scrambling and trans-splicing that result in either loss of partial exon or unusual exonic sequence rearrangements within or between RNA molecules.In addition,we show that the paired presence of SDR is necessary but not sufficient in SDR-mediated splicing in transient expression and stable transformation systems.We also show prokaryote is incapable of SDR-mediated premRNA splicing.展开更多
In order to detecting and tracking along the weld seam with rotating arc sensor in underwater welding,the highpressure water environment rotating arc welding hardware platform is established and welding experiments us...In order to detecting and tracking along the weld seam with rotating arc sensor in underwater welding,the highpressure water environment rotating arc welding hardware platform is established and welding experiments using rotating arc sensor is done. Different radius of rotating arc sensor is used. And the corresponding welding current and voltage is obtained,which is compared with the results of rotating arc sensor short-circuit process simulation model under high-pressure water environment established in this article. The results show that under high-pressure water environment,rotating arc radius should be optimized,otherwise the short-circuit-arcing cycle will transit to a short-circuit-arcing-abruption cycle,making the welding quality poor. At last the critical radius between the short-circuit-arcing cycle and short-circuit-arcing-abruption cycle under high-pressure water environment is obtained.展开更多
The effects of Reactive Black 5 utilized to cotton fabrics by short wet-steam process on the dyeing properties were investigated. This study will provide a theoretical reference for short wet-steam process of cotton f...The effects of Reactive Black 5 utilized to cotton fabrics by short wet-steam process on the dyeing properties were investigated. This study will provide a theoretical reference for short wet-steam process of cotton fabrics with bifunctional reactive dyes. The optimal amount of Selilao agent was 20 g/L, while the soaping and rubbing fastness of the dyed cotton fabrics were both reached to 4-5 rating.展开更多
An intelligent fuzzy c-means system for process monitoring and recognition of process disturbances during short- circuiting gas metal arc welding （GMAW） is introduced in this paper. The raw measured and statisticall...An intelligent fuzzy c-means system for process monitoring and recognition of process disturbances during short- circuiting gas metal arc welding （GMAW） is introduced in this paper. The raw measured and statistically test data of probability density distribution （ PDD ） and class frequency distribution （ CFD ） of welding electrical parameters are further processed into a 7-dimensional array which is designed to describe various welding conditions, and is employed as input vector of the intelligent fuzzy c-means system. The fuzzy c-means system is used to conduct process monitoring and automatic recognition. The correct recognition rate of 24 test data under 8 kinds of welding condition is 92%.展开更多
The modeling of the term structure of interest rates is one of primary topics for researches in financial economics. Here we consider models of the short interest rate in discrete processes. Our methodology of analysi...The modeling of the term structure of interest rates is one of primary topics for researches in financial economics. Here we consider models of the short interest rate in discrete processes. Our methodology of analysis follows the framework of discrete stochastic calculus.展开更多
【目的】针对高浑浊度矿井水处理技术存在处理工序长、超滤(UF)膜进水水质要求高、膜污染严重的问题,采用短流程超滤膜化学反应器(MCR)组器处理高浑浊度矿井水。【方法】在保留短流程超滤MCR工艺精简、集成度高、占地面积小的优势基础上...【目的】针对高浑浊度矿井水处理技术存在处理工序长、超滤(UF)膜进水水质要求高、膜污染严重的问题,采用短流程超滤膜化学反应器(MCR)组器处理高浑浊度矿井水。【方法】在保留短流程超滤MCR工艺精简、集成度高、占地面积小的优势基础上,对短流程超滤MCR技术的抗污染膜组器型式进行改进,探究高效膜污染控制组器型式;并对改进后组器的运行参数开展试验研究,通过优化运行通量、系统回收率、运行周期、反洗通量4个运行参数,考察不同运行条件对膜污染控制效果,从而确定抗污染膜组器的稳定运行参数,通过进水悬浮物浓度,考察短流程超滤MCR组器的进水条件。【结果】结果表明,短流程超滤MCR组器中振动模式的抗污染性能优于曝气模式,跨膜压差(TMP)低于曝气模式0.16~0.26 k Pa/d。而在振动模式中,线性振动模式TMP低于旋转振动模式0.5 k Pa/d,表明线性振动模式抗污染能力强,且线性振动模式的吨水能耗为0.03 k W·h、水阻能耗占比为28.8%,均优于旋转振动模式。此外,线性振动模式短流程超滤MCR组器在运行通量≤40L/(m^(2)·h),系统回收率≤97%,运行周期为45 min,反洗通量为60 L/(m^(2)·h)条件下,能保证膜抗污染效果,短流程超滤MCR组器进水耐受悬浮物质量浓度达到2000 mg/L,运行参数调整对产水水质无显著影响。【结论】振动模式短流程超滤MCR组器可有效减少处理工艺流程,放宽UF膜进水水质要求,缓解UF膜运行过程中膜污染的情况,可为高浑浊度矿井水工艺改造提供技术指导。展开更多
单晶硅作为常用的红外光学材料,随着红外技术的不断发展,对光学元件的质量要求也越来越高。为了获得高面形精度、高表面质量的复杂曲面单晶硅光学元件,提出了激光原位辅助超精密车削、磁流变和小磨头抛光组合抛光修形的短流程加工工艺...单晶硅作为常用的红外光学材料,随着红外技术的不断发展,对光学元件的质量要求也越来越高。为了获得高面形精度、高表面质量的复杂曲面单晶硅光学元件,提出了激光原位辅助超精密车削、磁流变和小磨头抛光组合抛光修形的短流程加工工艺。采用激光原位辅助超精密车削加工后的单晶硅元件具有低亚表面损伤,与未加激光时相比,激光原位辅助超精密车削后的单晶硅亚表面损伤由920 n m降低至318 nm。并经过多轮磁流变和小磨头抛光组合工艺迭代加工后,单晶硅光学元件面形精度和表面质量得到有效提升,最终面形精度RMS值优于1/50λ,表面粗糙度Ra值优于0.5 nm。该方法抑制了加工过程中的亚表面损伤,减少了后续抛光过程中损伤去除时间,有效提高了单晶硅光学元件加工效率,且面形精度和表面质量可满足高精度光学元件应用要求。展开更多
基金National Key Research and Development Program(2021YFB3401101)。
文摘Short process forming techniques for brazing and soldering materials can shorten the process,improve product quality,and increase production efficiency,which has received much attention from welding researchers.This review mainly summarized the research reports on short process forming techniques for brazing and soldering materials.Firstly,the traditional process and its shortcomings were presented.Secondly,the latest research of short process forming technologies,such as continuous casting technique,atomization powder technique,solder ball forming technique,and rapid solidification technique,was summarized,and the traditional forming performance of several brazing and soldering materials was introduced.Finally,the current restrictions and research trends of short process forming technique for brazing and solder materials were put forward,providing theoretical guidance and reference for related research and technique development in brazing and soldering field.
基金Financial supports from The National key research and development program(No.2016YFE0115300)The Natural Science Foundation of China(Nos.51790483,51625402,51790485 and 51801069)are greatly acknowledged+2 种基金Partial financial support came from The science and technology development program of Jilin Province(No.20190901010JC)The Changjiang Scholars Program(T2017035)the Program for JLU Science and Technology Innovative Research Team(JLUSTIRT,2017TD-09).
文摘Al-Mg-Si(AA6xxx)series alloys have been used widely in automotive industry for lightweight purpose.This work focuses on developing a short process for manufacturing Al-0.5Mg-1.3Si(wt.%)alloy sheets with good mechanical properties.Hereinto,a preparation route without homogenization was proposed on the basis of sub-rapid solidification(SRS)technique.The sample under SRS has fine microstructure and higher average partition coefficients of solute atoms,leading to weaker microsegregation owing to the higher cooling rate(160℃/s)than conventional solidification(CS,30℃/s).Besides,Mg atoms tend to be trapped in Al matrix under SRS,inducing suppression of Mg2Si,and promoting generation of Al Fe Si phase.After being solution heat treated(T4 state),samples following the SRS route have lower yield strength compared with that by CS route,indicating better formability in SRS sample.After undergoing pre-strain and artificial aging(T6 state),the SRS samples have comparable yield strength to CS samples,satisfying the service requirements.This work provides technological support to industrially manufacture high performance AA6xxx series alloys with competitive advantage by a novel,short and low-cost process,and open a door for the further development of twin-roll casting based on SRS technique in industries.
基金supported by the National Science Foundation of China (Grant no. 51408419)the National Key Technology Research and Development Program of China (Grant nos. 2014BAL02B02-03 and 2014BAC29B01)the Key Program for International S&T Cooperation Projects of China (Grant no. 2012DFG91380)
文摘As an important intermediate product, short-chain fatty acids（SCFAs） can be generated after hydrolysis and acidification from waste activated sludge, and then can be transformed to methane during anaerobic digestion process. In order to obtain more SCFA and methane,most studies in literatures were centered on enhancing the hydrolysis of sludge anaerobic digestion which was proved as un-efficient. Though the alkaline pretreatment in our previous study increased both the hydrolysis and acidification processes, it had a vast chemical cost which was considered uneconomical. In this paper, a low energy consumption pretreatment method, i.e. enhanced the whole three stages of the anaerobic fermentation processes at the same time, was reported, by which hydrolysis and acidification were both enhanced, and the SCFA and methane generation can be significantly improved with a small quantity of chemical input. Firstly, the effect of different pretreated temperatures and pretreatment time on sludge hydrolyzation was compared. It was found that sludge pretreated at 100°C for 60 min can achieve the maximal hydrolyzation. Further, effects of different initial p Hs on acidification of the thermal pretreated sludge were investigated and the highest SCFA was observed at initial p H 9.0with fermentation time of 6 d, the production of which was 348.63 mg COD/g VSS（6.8 times higher than the blank test） and the acetic acid was dominant acid. Then, the mechanisms for this new pretreatment significantly improving SCFA production were discussed. Finally,the effect of this low energy consumption pretreatment on methane generation was investigated.
基金supported by the National Key Basic Research Program (973 program) (No. 2006CB100205)the National Science Fund for Distinguished Young Scholars (No. 30825030)+2 种基金the National Natural Science Foundation of China (No. 30770466, 90717110, 30970260 and 30971752)the Earmarked Fund for Modern Agro-industry Technology Research System (No. nycytx-01)the National High Technology Research and Development Program of China (863 Program) (No. 2007AA10Z100)
文摘In several stress responsive gene loci of monocot cereal crops,we have previously identified an unusual posttranscriptional processing mediated by paired presence of short direct repeated （SDR） sequences at 5＇ and 3＇ splicing junctions that are distinct from conventional （U2/U12-type） splicing boundaries.By using the known SDR-containing sequences as probes,24 plant candidate genes involved in diverse functional pathways from both monocots and dicots that potentially possess SDR-mediated posttranscriptional processing were predicted in the GenBank database.The SDRs-mediated posttranscriptional processing events including cis-and trans-actions were experimentally detected in majority of the predicted candidates.Extensive sequence analysis demonstrates several types of SDR-associated splicing peculiarities including partial exon deletion,exon fragment repetition,exon fragment scrambling and trans-splicing that result in either loss of partial exon or unusual exonic sequence rearrangements within or between RNA molecules.In addition,we show that the paired presence of SDR is necessary but not sufficient in SDR-mediated splicing in transient expression and stable transformation systems.We also show prokaryote is incapable of SDR-mediated premRNA splicing.
基金supported by the National Natural Science Foundation of China(Grant No.51665016)founded by the China Scholarship Council(Grant No.201508360113)
文摘In order to detecting and tracking along the weld seam with rotating arc sensor in underwater welding,the highpressure water environment rotating arc welding hardware platform is established and welding experiments using rotating arc sensor is done. Different radius of rotating arc sensor is used. And the corresponding welding current and voltage is obtained,which is compared with the results of rotating arc sensor short-circuit process simulation model under high-pressure water environment established in this article. The results show that under high-pressure water environment,rotating arc radius should be optimized,otherwise the short-circuit-arcing cycle will transit to a short-circuit-arcing-abruption cycle,making the welding quality poor. At last the critical radius between the short-circuit-arcing cycle and short-circuit-arcing-abruption cycle under high-pressure water environment is obtained.
文摘The effects of Reactive Black 5 utilized to cotton fabrics by short wet-steam process on the dyeing properties were investigated. This study will provide a theoretical reference for short wet-steam process of cotton fabrics with bifunctional reactive dyes. The optimal amount of Selilao agent was 20 g/L, while the soaping and rubbing fastness of the dyed cotton fabrics were both reached to 4-5 rating.
基金The authors are grateful to the financial support provided by the National Natural Science Foundation of China under grant No. 51005106, Research Fund for the Doctoral Program of Jiangsu Uni- versity of Science and Technology under grant No. 35060902, A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘An intelligent fuzzy c-means system for process monitoring and recognition of process disturbances during short- circuiting gas metal arc welding （GMAW） is introduced in this paper. The raw measured and statistically test data of probability density distribution （ PDD ） and class frequency distribution （ CFD ） of welding electrical parameters are further processed into a 7-dimensional array which is designed to describe various welding conditions, and is employed as input vector of the intelligent fuzzy c-means system. The fuzzy c-means system is used to conduct process monitoring and automatic recognition. The correct recognition rate of 24 test data under 8 kinds of welding condition is 92%.
文摘The modeling of the term structure of interest rates is one of primary topics for researches in financial economics. Here we consider models of the short interest rate in discrete processes. Our methodology of analysis follows the framework of discrete stochastic calculus.
文摘【目的】针对高浑浊度矿井水处理技术存在处理工序长、超滤(UF)膜进水水质要求高、膜污染严重的问题,采用短流程超滤膜化学反应器(MCR)组器处理高浑浊度矿井水。【方法】在保留短流程超滤MCR工艺精简、集成度高、占地面积小的优势基础上,对短流程超滤MCR技术的抗污染膜组器型式进行改进,探究高效膜污染控制组器型式;并对改进后组器的运行参数开展试验研究,通过优化运行通量、系统回收率、运行周期、反洗通量4个运行参数,考察不同运行条件对膜污染控制效果,从而确定抗污染膜组器的稳定运行参数,通过进水悬浮物浓度,考察短流程超滤MCR组器的进水条件。【结果】结果表明,短流程超滤MCR组器中振动模式的抗污染性能优于曝气模式,跨膜压差(TMP)低于曝气模式0.16~0.26 k Pa/d。而在振动模式中,线性振动模式TMP低于旋转振动模式0.5 k Pa/d,表明线性振动模式抗污染能力强,且线性振动模式的吨水能耗为0.03 k W·h、水阻能耗占比为28.8%,均优于旋转振动模式。此外,线性振动模式短流程超滤MCR组器在运行通量≤40L/(m^(2)·h),系统回收率≤97%,运行周期为45 min,反洗通量为60 L/(m^(2)·h)条件下,能保证膜抗污染效果,短流程超滤MCR组器进水耐受悬浮物质量浓度达到2000 mg/L,运行参数调整对产水水质无显著影响。【结论】振动模式短流程超滤MCR组器可有效减少处理工艺流程,放宽UF膜进水水质要求,缓解UF膜运行过程中膜污染的情况,可为高浑浊度矿井水工艺改造提供技术指导。
文摘单晶硅作为常用的红外光学材料,随着红外技术的不断发展,对光学元件的质量要求也越来越高。为了获得高面形精度、高表面质量的复杂曲面单晶硅光学元件,提出了激光原位辅助超精密车削、磁流变和小磨头抛光组合抛光修形的短流程加工工艺。采用激光原位辅助超精密车削加工后的单晶硅元件具有低亚表面损伤,与未加激光时相比,激光原位辅助超精密车削后的单晶硅亚表面损伤由920 n m降低至318 nm。并经过多轮磁流变和小磨头抛光组合工艺迭代加工后,单晶硅光学元件面形精度和表面质量得到有效提升,最终面形精度RMS值优于1/50λ,表面粗糙度Ra值优于0.5 nm。该方法抑制了加工过程中的亚表面损伤,减少了后续抛光过程中损伤去除时间,有效提高了单晶硅光学元件加工效率,且面形精度和表面质量可满足高精度光学元件应用要求。
