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88篇 您的检索式:作者名="Changhe LI"
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1Urban land expansion and arable land loss of the major cities in China in the 1990s显示文摘Based on the land-use data in 1990 and 2000, determined by interpreting Landsat Thematic Mapper (TM) imagery, this paper defines the extent of urban construction land, and extracts patches of urban construction land of 145 cities with the largest areas in 1990 and arable land patches around these cities. With these data, this paper analyzes the characteristics of ur- ban construction land expansion and the consequent arable land loss in East, Middle and West China, and further identifies the social, economic and spatial factors of the urban land use changes, using GIS (Geographical Information System) and multivariate regression approaches. The results show that total urban land of the 145 cities expanded by 39.8%, with about 70% of the new urban land converted from arable land in the 1990s. The urban land expansion varied among the three regions, with a value of 43.0% in the East, 33.1% in the West (33.1%) and 17.8% in the Middle. Moreover, mean urban construction land per capita increased by10.7% in the East, but it decreased by 7.7% in the Middle, 1.4% in the West. Statistical analysis indicated that total wages of staff and workers could best explain the differences of urban land expansion.TAN Minghong LI Xiubin LU Changhe 2005Science China Earth Sciences2005,48,9:32
2Grinding temperature and energy ratio coefficient in MQL grinding of high-temperature nickel-base alloy by using different vegetable oils as base oil显示文摘Vegetable oil can be used as a base oil in minimal quantity of lubrication(MQL). This study compared the performances of MQL grinding by using castor oil, soybean oil, rapeseed oil, corn oil, sunflower oil, peanut oil, and palm oil as base oils. A K-P36 numerical-control precision surface grinder was used to perform plain grinding on a workpiece material with a high-temperature nickel base alloy. A YDM–III 99 three-dimensional dynamometer was used to measure grinding force,and a clip-type thermocouple was used to determine grinding temperature. The grinding force, grinding temperature, and energy ratio coefficient of MQL grinding were compared among the seven vegetable oil types. Results revealed that(1) castor oil-based MQL grinding yields the lowest grinding force but exhibits the highest grinding temperature and energy ratio coefficient;(2) palm oil-based MQL grinding generates the second lowest grinding force but shows the lowest grinding temperature and energy ratio coefficient;(3) MQL grinding based on the five other vegetable oils produces similar grinding forces, grinding temperatures, and energy ratio coefficients, with values ranging between those of castor oil and palm oil;(4) viscosity significantly influences grinding force and grinding temperature to a greater extent than fatty acid varieties and contents in vegetable oils;(5) although more viscous vegetable oil exhibits greater lubrication and significantly lower grinding force than less viscous vegetable oil, high viscosity reduces the heat exchange capability of vegetable oil and thus yields a high grinding temperature;(6) saturated fatty acid is a more efficient lubricant than unsaturated fatty acid; and(7) a short carbon chain transfers heat more effectively than a long carbon chain. Palm oil is the optimum base oil of MQL grinding, and this base oil yields 26.98 N tangential grinding force,87.10 N normal grinding force, 119.6 °C grinding temperature, and 42.7% energy ratio coefficient.Li Benkai Li Changhe Zhang Yanbin Wang Yaogang Jia Dongzhou Yang Min 2016Chinese Journal of Aeronautics2016,29,4:20
3Advances in fabrication of ceramic corundum abrasives based on sol–gel process显示文摘Corundum abrasives with good chemical stability can be fabricated into various free abrasives and bonded abrasive tools that are widely used in the precision machining of various parts.However,these abrasives cannot satisfy the machining requirements of difficult-to-machine materials with high hardness,high strength,and strong wearing resistance.Although superhard abrasives can machine the above-mentioned materials,their dressing and manufacturing costs are high.By contrast,ceramic corundum abrasives fabricated by sol–gel method is a costeffective product between conventional and superhard abrasives.Ceramic corundum abrasives exhibit self-sharpening and high toughness.In this review,the optimization methods of ceramic corundum abrasive properties are introduced from three aspects:precursor synthesis,particle shaping,and sintering.Firstly,the functional mechanism of seeds and additives on the microstructural and mechanical properties of abrasives is analyzed.Specifically,seeds can reduce the phase transition temperature and improve fracture toughness.The grain size and uniformly dense structure can be controlled by applying an appropriate amount of multicomponent additives.Then,the urgent need of engineering application and machinability of special shape ceramic corundum abrasives is reviewed,and three methods of abrasive shaping are summarized.The micromold replication technique is highly advanced and can be used to prepare functional abrasives.Additionally,the influence of a new sintering method,namely,two-step sintering technique,on the microstructural and mechanical performance of ceramic corundum abrasives is summarized.Finally,the challenge and developmental trend of the optimization of ceramic corundum abrasives are prospected.Baoteng HUANG Changhe LI Yanbin ZHANG Wenfeng DING Min YANG Yuying YANG Han ZHAI Xuefeng XU Dazhong WANG Sujan DEBNATH Muhammad JAMIL Hao Nan Li Hafiz Muhammad ALI Munish Kumar GUPTA Zafar SAID 2021Chinese Journal of Aeronautics2021,34,6:11
4Specific grinding energy and surface roughness of nanoparticle jet minimum quantity lubrication in grinding显示文摘Nanoparticles with the anti-wear and friction reducing features were applied as cooling lubricant in the grinding fluid. Dry grinding, flood grinding, minimal quantity of lubrication(MQL), and nanoparticle jet MQL were used in the grinding experiments. The specific grinding energy of dry grinding, flood grinding and MQL were 84, 29.8, 45.5 J/mm^3, respectively. The specific grinding energy significantly decreased to 32.7 J/mm^3 in nanoparticle MQL. Compared with dry grinding, the surface roughness values of flood grinding, MQL, and nanoparticle jet MQL were significantly reduced with the surface topography profile values reduced by 11%, 2.5%, and 10%,respectively, and the ten point height of microcosmic unflatness values reduced by 1.5%, 0.5%,and 1.3%, respectively. These results verified the satisfactory lubrication effects of nanoparticle MQL. MoS_2, carbon nanotube(CNT), and ZrO_2 nanoparticles were also added in the grinding fluid of nanoparticle jet MQL to analyze their grinding surface lubrication effects. The specific grinding energy of MoS_2 nanoparticle was only 32.7 J/mm^3, which was 8.22% and 10.39% lower than those of the other two nanoparticles. Moreover, the surface roughness of workpiece was also smaller with MoS_2 nanoparticle, which indicated its remarkable lubrication effects. Furthermore,the role of MoS_2 particles in the grinding surface lubrication at different nanoparticle volume concentrations was analyzed. MoS_2 volume concentrations of 1%, 2%, and 3% were used.Experimental results revealed that the specific grinding energy and the workpiece surface roughness initially increased and then decreased as MoS_2 nanoparticle volume concentration increased.Satisfactory grinding surface lubrication effects were obtained with 2% MoS_2 nanoparticle volume concentration.Zhang Dongkun Li Changhe Jia Dongzhou Zhang Yanbin Zhang Xiaowei 2015Chinese Journal of Aeronautics2015,28,2:10
5Milling surface roughness for 7050 aluminum alloy cavity influenced by nozzle position of nanofluid minimum quantity lubrication显示文摘In nanofluid minimum quantity lubrication(NMQL)milling of aviation aluminum alloy,it is the bottleneck problem to adjust the position parameters(target distance,incidence angle,and elevation angle)of the nozzle to improve the surface roughness of milling,which has large and uncontrollable errors.In this paper,the influence law of milling cutter speed,helical angle,and cavity shape on the flow field around the milling cutter was studied,and the optimal nozzle profile parameters were obtained.Using 7050 aluminum alloy as the workpiece material,the milling experiment of the NMQL cavity was conducted by utilizing cottonseed oil-based Al2 O3 nanofluid.Results show that the high velocity of the surrounding air flow field and the strong gas barrier could be attributed to high rotating velocities of the milling cutter.The incidence angle of the nozzle was consistent with the helical angle of the milling cutter,the target distance was appropriate at 25–30 mm,and the elevation angle was suitable at 60°–65°.The range and variance analyses of the signal-to-noise ratio of milling force and roughness were performed,and the chip morphology was observed and analyzed.The results show that the optimal combination of nozzle position parameters was the target distance of 30 mm,the incidence angle of 35°,and the elevation angle of 60°.Among these parameters,target distance had the largest impact on cutting performance with a contribution rate of more than 55%,followed by incidence angle and elevation contribution rate.Analysis by orthogonal experiment revealed that the nozzle position parameters were appropriate,and Ra(0.087 lm)was reduced by 30.4%from the maximum value(0.125 lm).Moreover,Rsm(0.05 mm)was minimum,which was 36%lower than that of the seventh group(Rsm=0.078 mm).Zhenjing DUAN Changhe LI Yanbin ZHANG Lan DONG Xiufang BAI Min YANG Dongzhou JIA Runze LI Huajun CAO Xuefeng XU 2021Chinese Journal of Aeronautics2021,34,6:10
6Prediction on grinding force during grinding powder metallurgy nickel-based superalloy FGH96 with electroplated CBN abrasive wheel显示文摘In this article,a grinding force model,which is on the basis of cutting process of single abrasive grains combined with the method of theoretical derivation and empirical formula by analyzing the formation mechanism of grinding force,was established.Three key factors have been taken into accounts in this model,such as the contact friction force between abrasive grains and materials,the plastic deformation of material in the process of abrasive plowing,and the shear strain effect of material during the process of cutting chips formation.The model was finally validated by the orthogonal grinding experiment of powder metallurgy nickel-based superalloy FGH96 by using the electroplated CBN abrasive wheel.Grinding force values of prediction and experiment were in good consistency.The errors of tangential grinding force and normal grinding force were 9.8%and 13.6%,respectively.The contributions of sliding force,plowing force and chip formation force were also analyzed.In addition,the tangential forces of sliding,plowing and chip formation are 14%,19%and 11%of the normal forces on average,respectively.The pro-posed grinding forcemodel is not only in favor of optimizing the grinding parameters and improving grinding efficiency,but also contributes to study some other grinding subjects(e.g.abrasive wheel wear,grinding heat,residual stress).Benkai LI Chenwei DAI Wenfeng DING Changyong YANG Changhe LI Olga KULIK Vyacheslav SHUMYACHER 2021Chinese Journal of Aeronautics2021,34,8:10
7Cryogenic minimum quantity lubrication machining: from mechanism to application显示文摘Cutting fluid plays a cooling-lubrication role in the cutting of metal materials.However,the substantial usage of cutting fluid in traditional flood machining seriously pollutes the environment and threatens the health of workers.Environmental machining technologies,such as dry cutting,minimum quantity lubrication(MQL),and cryogenic cooling technology,have been used as substitute for flood machining.However,the insufficient cooling capacity of MQL with normal-temperature compressed gas and the lack of lubricating performance of cryogenic cooling technology limit their industrial application.The technical bottleneck of mechanical-thermal damage of difficult-to-cut materials in aerospace and other fields can be solved by combining cryogenic medium and MQL.The latest progress of cryogenic minimum quantity lubrication(CMQL)technology is reviewed in this paper,and the key scientific issues in the research achievements of CMQL are clarified.First,the application forms and process characteristics of CMQL devices in turning,milling,and grinding are systematically summarized from traditional settings to innovative design.Second,the cooling-lubrication mechanism of CMQL and its influence mechanism on material hardness,cutting force,tool wear,and workpiece surface quality in cutting are extensively revealed.The effects of CMQL are systematically analyzed based on its mechanism and application form.Results show that the application effect of CMQL is better than that of cryogenic technology or MQL alone.Finally,the prospect,which provides basis and support for engineering application and development of CMQL technology,is introduced considering the limitations of CMQL.Mingzheng LIU Changhe LI Yanbin ZHANG Qinglong AN Min YANG Teng GAO Cong MAO Bo LIU Huajun CAO Xuefeng XU Zafar SAID Sujan DEBNATH Muhammad JAMIL Hafz Muhammad ALI Shubham SHARMA 2021Frontiers of Mechanical Engineering2021,16,4:8
8Milling Force Model for Aviation Aluminum Alloy: Academic Insight and Perspective Analysis显示文摘Aluminum alloy is the main structural material of aircraft,launch vehicle,spaceship,and space station and is processed by milling.However,tool wear and vibration are the bottlenecks in the milling process of aviation aluminum alloy.The machining accuracy and surface quality of aluminum alloy milling depend on the cutting parameters,material mechanical properties,machine tools,and other parameters.In particular,milling force is the crucial factor to determine material removal and workpiece surface integrity.However,establishing the prediction model of milling force is important and difficult because milling force is the result of multiparameter coupling of process system.The research progress of cutting force model is reviewed from three modeling methods:empirical model,finite element simulation,and instantaneous milling force model.The problems of cutting force modeling are also determined.In view of these problems,the future work direction is proposed in the following four aspects:(1)high-speed milling is adopted for the thin-walled structure of large aviation with large cutting depth,which easily produces high residual stress.The residual stress should be analyzed under this particular condition.(2)Multiple factors(e.g.,eccentric swing milling parameters,lubrication conditions,tools,tool and workpiece deformation,and size effect)should be considered comprehensively when modeling instantaneous milling forces,especially for micro milling and complex surface machining.(3)The database of milling force model,including the corresponding workpiece materials,working condition,cutting tools(geometric figures and coatings),and other parameters,should be established.(4)The effect of chatter on the prediction accuracy of milling force cannot be ignored in thin-walled workpiece milling.(5)The cutting force of aviation aluminum alloy milling under the condition of minimum quantity lubrication(mql)and nanofluid mql should be predicted.Zhenjing Duan Changhe Li Wenfeng Ding Yanbin Zhang Min Yang Teng Gao Huajun Cao Xuefeng Xu Dazhong Wang Cong Mao Hao Nan Li Gupta Munish Kumar Zafar Said Sujan Debnath Muhammad Jamil Hafiz Muhammad Ali 2021Chinese Journal of Mechanical Engineering2021,34,1:7
9Nano-enhanced biolubricant in sustainable manufacturing:From processability to mechanisms显示文摘To eliminate the negative effect of traditional metal-working fluids and achieve sustainable manufacturing,the usage of nano-enhanced biolubricant(NEBL)is widely researched in minimum quantify lubrication(MQL)machining.It's improved tool wear and surface integrity have been preliminarily verified by experimental studies.The previous review papers also concluded the major influencing factors of processability including nano-enhancer and lubricant types,NEBL concentration,micro droplet size,and so on.Nevertheless,the complex action of NEBL,from preparation,atomization,infiltration to heat transfer and anti-friction,is indistinct which limits preparation of process specifications and popularity in factories.Especially in the complex machining process,in-depth understanding is difficult and meaningful.To fll this gap,this paper concentrates on the comprehensive quantitative assessment of processability based on tribological,thermal,and machined surface quality aspects for NEBL application in turning,milling,and grinding.Then it attempts to answer mechanisms systematically considering multi-factor influence of molecular structure,physicochemical properties,concentration,and dispersion.Firstly,this paper reveals advanced lubrication and heat transfer mechanisms of NEBL by quantitative comparison with biolubricant-based MQL machining.Secondly,the distinctive filmformation,atomization,and infiltration mechanisms of NEBL,as distinguished from metal-working fluid,are clarified combining with its unique molecular structure and physical properties.Furtherly,the process optimization strategy is concluded based on the synergistic relationship analysis among process variables,physicochemical properties,machining mechanisms,and performance of NEBL.Finally,the future development directions are put forward aiming at current performance limitations of NEBL,which requires improvement on preparation and jet methods respects.This paper will help scientists deeply understand effective mechanism,formulate process specifications,and find future development trend of this technology.Yanbin ZHANG Hao Nan LI Changhe LI Chuanzhen HUANG Hafiz Muhammad ALI Xuefeng XU Cong MAO Wenfeng DING Xin CUI Min YANG Tianbiao YU Muhammad JAMIL Munish Kumar GUPTA Dongzhou JIA Zafar SAID 2022Friction2022,10,6:5
10Analysis of grinding mechanics and improved grinding force model based on randomized grain geometric characteristics显示文摘Too high grinding force will lead to a large increase in specific grinding energy, resulting in high temperature in grinding zone, especially for the aerospace difficult cutting metal materials,seriously affecting the surface quality and accuracy. At present, the theoretical models of grinding force are mostly based on the assumption of uniform or simplified morphological characteristics of grains, which is inconsistent with the actual grains. Especially for non-engineering grinding wheel,most geometric characteristics of grains are ignored, resulting in the calculation accuracy that cannot guide practical production. Based on this, an improved grinding force model based on random grain geometric characteristics is proposed in this paper. Firstly, the surface topography model of CBN grinding wheel is established, and the effective grain determination mechanism in grinding zone is revealed. Based on the known grinding force model and mechanical behavior of interaction between grains and workpiece in different stages, the concept of grain effective action area is proposed. The variation mechanism of effective action area under the influence of grain geometric and spatial characteristics is deeply analyzed, and the calculation method under random combination of five influencing parameters is obtained. The numerical simulation is carried out to reveal the dynamic variation process of grinding force in grinding zone. In order to verify the theoretical model, the experiments of dry grinding Ti-6Al-4 V are designed. The experimental results show that under different machining parameters, the results of numerical calculation and experimental measurement are in good agreement, and the minimum error value is only 2.1 %, which indicates that the calculation accuracy of grinding force model meets the requirements and is feasible. This study will provide a theoretical basis for optimizing the wheel structure, effectively controlling the grinding force range, adjusting the grinding zone temperature and improving the workpiece machining quality in the industrial grinding process.Mingzheng LIU Changhe LI Yanbin ZHANG Min YANG Teng GAO Xin CUI Xiaoming WANG Wenhao XU Zongming ZHOU Bo LIU Zafar SAID Runze LI Shubham SHARMA 2023Chinese Journal of Aeronautics2023,36,7:5
11Multistage analysis method for detection of effective herb prescription from clinical data显示文摘为特定的疾病条件或特别的耐心的组决定有效繁体中文药(TCM ) 治疗是因为复杂个性化的表明,在真实世界的病人和在临床的背景规定的个性化的联合治疗要求调查的一个困难的问题。在这研究,集成倾向大小写匹配的一个多级式的分析方法,复杂网络分析,和植物给了丰富分析被建议为特别疾病识别有效植物药方(例如,失眠) 。首先,匹配的倾向大小写被使用匹配临床的盒子。然后,核心网络抽取和植物集合丰富被联合检测核心有效植物药方。基于有效性的相互的信息被用来检测强壮的 herbsymptom 关系。这个方法在一个 TCM 临床的数据集合上被使用, 955 个病人从设计得好的观察研究收集了。结果与更高的有效性率揭示了那组植物药方(76.9% 对 42.8% 为匹配的样品;94.2% 对 84.9% 为所有样品) 与原版相比,药方被发现。有症状表明的特别的耐心的组也被识别帮助调查有效植物药方的指示。Kuo Yang Runshun Zhang Liyun He Yubing Li Wenwen Liu Changhe Yu Yanhong Zhang Xinlong Li Yan Liu Weiming Xu Xuezhong Zhou Baoyan Liu 2018Frontiers of Medicine2018,12,2:5
12Electrostatic atomization minimum quantity lubrication machining:from mechanism to application显示文摘Metal cutting fluids(MCFs)under flood conditions do not meet the urgent needs of reducing carbon emission.Biolubricant-based minimum quantity lubrication(MQL)is an effective alternative to flood lubrication.However,pneumatic atomization MQL has poor atomization properties,which is detrimental to occupational health.Therefore,electrostatic atomization MQL requires preliminary exploratory studies.However,systematic reviews are lacking in terms of capturing the current research status and development direction of this technology.This study aims to provide a comprehensive review and critical assessment of the existing understanding of electrostatic atomization MQL.This research can be used by scientists to gain insights into the action mechanism,theoretical basis,machining performance,and development direction of this technology.First,the critical equipment,eco-friendly atomization media(biolubricants),and empowering mechanisms of electrostatic atomization MQL are presented.Second,the advanced lubrication and heat transfer mechanisms of biolubricants are revealed by quantitatively comparing MQL with MCF-based wet machining.Third,the distinctive wetting and infiltration mechanisms of electrostatic atomization MQL,combined with its unique empowering mechanism and atomization method,are compared with those of pneumatic atomization MQL.Previous experiments have shown that electrostatic atomization MQL can reduce tool wear by 42.4%in metal cutting and improve the machined surface Ra by 47%compared with pneumatic atomization MQL.Finally,future development directions,including the improvement of the coordination parameters and equipment integration aspects,are proposed.Wenhao Xu Changhe Li Yanbin Zhang Hafiz Muhammad Ali Shubham Sharma Runze Li Min Yang Teng Gao Mingzheng Liu Xiaoming Wang Zafar Said Xin Liu Zongming Zhou 2022International Journal of Extreme Manufacturing2022,4,4:4
13Aridity trend and response to vegetation restoration in the loess hilly region of northern Shaanxi Province显示文摘处于干燥湿的条件检测变化趋势能为开发战略措施减轻全球温暖的影响提供信息,特别地在干燥区域。作为一个盒子区域在黄土高原上拿北 Shaanxi 的多山的区域,这研究在 19812012 期间分析了干旱变化的趋势,并且探索了在 1999 实现的 Grain-for-Green (GFG ) 节目支持的植被恢复的效果。结果显示在这个区域的干旱被 0.88% 非显著地在 19812012 期间每年增加,显示出一个弄干的趋势。这个弄干的趋势和振幅被 GFG 节目支持的植被恢复的影响改变,基于二调查结果。第一是干旱变化趋于在 19811999 期间增加当它转弯了在 20002012 期间减少时,与从 2.45% ~ 1.06% 改变的地区性的吝啬的相对变化率。这区别在黄土溪谷区域是更显著的,在植被更显然被改进的地方。第二是由 EVI 显示了的吝啬的植被范围在县水平每年增加了 0.90% ~ 4.32% ,当干旱在 20002012 期间每年在 0.14% ~ 2.32% 减少了时。用吝啬的县数据的回归分析显示变化干旱评价,在干旱衰落的一半附近说明那是否定地与有决心的系数的 EVI 的有关(R < 啜 class= “ a-plus-plus ” > 0.56 的 2 ) 被 EVI 变化解释。这效果的机制是复杂的,但是植被改进导致的风速度衰落能是一个重要贡献者,这被发现。这个区域在 19812012 期间变得更干燥,这被结束,但是 eco 恢复减少了弄干的速度。然而,这个结论涉及无常,并且进一步的学习基于实验被需要证实支持 GFG 的植被恢复的效果。LI Wangjun LU Changhe 2015Journal of Geographical Sciences2015,25,3:4
14Prevention of Mother-To-Child Transmission of HIV-China,2011-2020显示文摘ABSTRACT Introduction:Prevention of mother-to-child transmission(PMTCT)of human immunodeficiency virus(HIV)is a global health focus in most parts of the world.The World Health Organization(WHO)launched the dual Elimination of Mother-to-Child Transmission(EMTCT)of HIV and syphilis initiative and released global guidance on criteria and processes for validation of the EMTCT in 2014.The purpose of this report was to analyze the key validation indicators of EMTCT of HIV in China from 2011 to 2020 and to provide relevant basis information for the implementation of EMTCT action in China.Xiaoyan Wang Qian Wang Changhe Wang Tong Zhang Zhixin Li Zhonghua Ma Ailing Wang 2021China CDC weekly2021,3,48:3
15Comparative assessment of force,temperature,and wheel wear in sustainable grinding aerospace alloy using biolubricant显示文摘The substitution of biolubricant for mineral cutting fluids in aerospace material grinding is an inevitable development direction,under the requirements of the worldwide carbon emission strategy.However,serious tool wear and workpiece damage in difficult-to-machine material grinding challenges the availability of using biolubricants via minimum quantity lubrication.The primary cause for this condition is the unknown and complex influencing mechanisms of the biolubricant physicochemical properties on grindability.In this review,a comparative assessment of grindability is performed using titanium alloy,nickel-based alloy,and high-strength steel.Firstly,this work considers the physicochemical properties as the main factors,and the antifriction and heat dissipation behaviours of biolubricant in a high temperature and pressure interface are comprehensively analysed.Secondly,the comparative assessment of force,temperature,wheel wear and workpiece surface for titanium alloy,nickel-based alloy,and high-strength steel confirms that biolubricant is a potential replacement of traditional cutting fluids because of its improved lubrication and cooling performance.High-viscosity biolubricant and nano-enhancers with high thermal conductivity are recommended for titanium alloy to solve the burn puzzle of the workpiece.Biolubricant with high viscosity and high fatty acid saturation characteristics should be used to overcome the bottleneck of wheel wear and nickel-based alloy surface burn.The nano-enhancers with high hardness and spherical characteristics are better choices.Furthermore,a different option is available for high-strength steel grinding,which needs low-viscosity biolubricant to address the debris breaking difficulty and wheel clogging.Finally,the current challenges and potential methods are proposed to promote the application of biolubricant.Xin CUI Changhe LI Yanbin ZHANG Wenfeng DING Qinglong AN Bo LIU Hao Nan LI Zafar SAID Shubham SHARMA Runze LI Sujan DEBNATH 2023Frontiers of Mechanical Engineering2023,18,1:3
16Study on drying and combustion process in grate-CFB incinerator显示文摘The drying and combustion process in the combined grate and circulating fluidized bed(grate-CFB) municipal solid waste(MSW) incinerator was investigated experimentally and mathematically.The drying grate bed was simulated by a muffle furnace,which could be controlled at a constant tempera-ture level.The kind of wastes,thickness of waste layer fed and temperature were chosen as the ad-justable parameters to study their effect on the drying process.The experimental results indicated that the hydrophilic wastes were more difficult to be dried than the hydrophobic wastes.The higher the temperature is the easier the waste is to be dried.The thinner waste layer is favorable to drying the waste.The pyrolysis experiment in the furnace showed that the higher temperature level could reduce the conversion rate of carbon to carbon monoxide.The semi-empirical mathematical model that in-cluded the bed material distribution submodel,volatile matter release submodel,carbon particle combustion submodel and so on was proposed.A 260 t/d grate-CFB incinerator was modeled and the model predicted bulk density agreed with the measured value from industrial field test.The predicted flue gas(e.g.CO2,CO) concentration deviated slightly from the industrial test data.The parameters and variables used in the model were determined by the experiments or practical field test.This model can be used to design the grate-CFB incinerator and guide its operation.QingHai Li YanGuo Zhang MeiQian Chen AiHong Meng ChangHe Chen 2009Science China(Technological Sciences)2009,52,5:3
17Machinability of ultrasonic vibration-assisted micro-grinding in biological bone using nanolubricant显示文摘Bone grinding is an essential and vital procedure in most surgical operations.Currently,the insufficient cooling capacity of dry grinding,poor visibility of drip irrigation surgery area,and large grinding force leading to high grinding temperature are the technical bottlenecks of micro-grinding.A new micro-grinding process called ultrasonic vibration-assisted nanoparticle jet mist cooling(U-NJMC)is innovatively proposed to solve the technical problem.It combines the advantages of ultrasonic vibration(UV)and nanoparticle jet mist cooling(NJMC).Notwithstanding,the combined effect of multi parameter collaborative of U-NJMC on cooling has not been investigated.The grinding force,friction coefficient,specific grinding energy,and grinding temperature under dry,drip irrigation,UV,minimum quantity lubrication(MQL),NJMC,and U-NJMC micro-grinding were compared and analyzed.Results showed that the minimum normal grinding force and tangential grinding force of U-NJMC micro-grinding were 1.39 and 0.32 N,which were 75.1%and 82.9%less than those in dry grinding,respectively.The minimum friction coefficient and specific grinding energy were achieved using U-NJMC.Compared with dry,drip,UV,MQL,and NJMC grinding,the friction coefficient of U-NJMC was decreased by 31.3%,17.0%,19.0%,9.8%,and 12.5%,respectively,and the specific grinding energy was decreased by 83.0%,72.7%,77.8%,52.3%,and 64.7%,respectively.Compared with UV or NJMC alone,the grinding temperature of U-NJMC was decreased by 33.5%and 10.0%,respectively.These results showed that U-NJMC provides a novel approach for clinical surgical micro-grinding of biological bone.Yuying YANG Min YANG Changhe LI Runze LI Zafar SAID Hafiz Muhammad ALI Shubham SHARMA 2023Frontiers of Mechanical Engineering2023,18,1:3
18Bleaching effect and nonvolatile holographic storage in doubly doped LiNbO_3:Fe:Cu crystals显示文摘The bleaching effect, i.e. the crystal shows that decoloration after it is illuminated by ultraviolet light, has been observed in congruent LiNbO3:Fe:Cu crystals. Based on this bleaching effect, a new technique including the recording phase by two interfering red beams and fixing phase by both UV light and a coherent red beam has been experimentally investigated to realize nonvolatile holographic storage in LiNbO3:Fe:Cu. The results of proof-of-concept experiments confirm that bleaching effect becomes an alternative physical mechanism for nonvolatile holographic storage with high recording sensitivity and weak light-induced scattering noise.LIU Dean, LIU Liren, ZHOU Changhe, REN Liyong & LI GuangaoShanghai Institute of Optics and Fine Mechanics, Chinese Academy ofSciences, Shanghai 201800, ChinaDepartment of Physics, Nankai University, Tianjin 300071, China 2002Chinese Science Bulletin2002,47,20:3
19Fiber-reinforced composites in milling and grinding:machining bottlenecks and advanced strategies显示文摘Fiber-reinforced composites have become the preferred material in the fields of aviation and aerospace because of their high-strength performance in unit weight.The composite components are manufactured by near netshape and only require finishing operations to achieve final dimensional and assembly tolerances.Milling and grinding arise as the preferred choices because of their precision processing.Nevertheless,given their laminated,anisotropic,and heterogeneous nature,these materials are considered difficult-to-machine.As undesirable results and challenging breakthroughs,the surface damage and integrity of these materials is a research hotspot with important engineering significance.This review summarizes an up-to-date progress of the damage formation mechanisms and suppression strategies in milling and grinding for the fiber-reinforced composites reported in the literature.First,the formation mechanisms of milling damage,including delamination,burr,and tear,are analyzed.Second,the grinding mechanisms,covering material removal mechanism,thermal mechanical behavior,surface integrity,and damage,are discussed.Third,suppression strategies are reviewed systematically from the aspects of advanced cutting tools and technologies,including ultrasonic vibration-assisted machining,cryogenic cooling,minimum quantity lubrication(MQL),and tool optimization design.Ultrasonic vibration shows the greatest advantage of restraining machining force,which can be reduced by approximately 60%compared with conventional machining.Cryogenic cooling is the most effective method to reduce temperature with a maximum reduction of approximately 60%.MQL shows its advantages in terms of reducing friction coefficient,force,temperature,and tool wear.Finally,research gaps and future exploration directions are prospected,giving researchers opportunity to deepen specific aspects and explore new area for achieving high precision surface machining of fiber-reinforced composites.Teng GAO Yanbin ZHANG Changhe LI Yiqi WANG Yun CHEN Qinglong AN Song ZHANG Hao Nan LI Huajun CAO Hafiz Muhammad ALI Zongming ZHOU Shubham SHARMA 2022Frontiers of Mechanical Engineering2022,17,2:3
20Minimum quantity lubrication machining of aeronautical materials using carbon group nanolubricant: From mechanisms to application显示文摘It is an inevitable trend of sustainable manufacturing to replace flood and dry machining with minimum quantity lubrication(MQL)technology.Nevertheless,for aeronautical difficult-tomachine materials,MQL couldn’t meet the high demand of cooling and lubrication due to high heat generation during machining.Nano-biolubricants,especially non-toxic carbon group nano-enhancers(CGNs)are used,can solve this technical bottleneck.However,the machining mechanisms under lubrication of CGNs are unclear at complex interface between tool and workpiece,which characterized by high temperature,pressure,and speed,limited its application in factories and necessitates in-depth understanding.To fill this gap,this study concentrates on the comprehensive quantitative assessment of tribological characteristics based on force,tool wear,chip,and surface integrity in titanium alloy and nickel alloy machining and attempts to answer mechanisms systematically.First,to establish evaluation standard,the cutting mechanisms and performance improvement behavior covering antifriction,antiwear,tool failure,material removal,and surface formation of MQL were revealed.Second,the unique film formation and lubrication behaviors of CGNs in MQL turning,milling,and grinding are concluded.The influence law of molecular structure and micromorphology of CGNs was also answered and optimized options were recommended by considering diverse boundary conditions.Finally,in view of CGNs limitations in MQL,the future development direction is proposed,which needs to be improved in thermal stability of lubricant,activity of CGNs,controllable atomization and transportation methods,and intelligent formation of processing technology solutions.Xin CUI Changhe LI Wenfeng Ding Yun CHEN Cong MAO Xuefeng XU Bo LIU Dazhong WANG Hao Nan LI Yanbin ZHANG Zafar SAID Sujan DEBNATH Muhammad JAMIL Hafiz Muhammad ALI Shubham SHARMA 2022Chinese Journal of Aeronautics2022,35,11:3
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