Flaking on high-moisture corn （wet corn） by hot-air heating was studied in the paper. The wet-heating approach was beneficial to improve corn gelatinization by experimental results. By the experiments, a set of opti...Flaking on high-moisture corn （wet corn） by hot-air heating was studied in the paper. The wet-heating approach was beneficial to improve corn gelatinization by experimental results. By the experiments, a set of optimal parameters was obtained： hot-air temperature 120-130℃, heating duration 70 min, gap between rollers 0.5 -1.0 mm, 150-200 r·min^-1 for rotational speed of rollers.展开更多
Magnesium potassium phosphate cement(MKPC)coatings exhibit potential for carbon steel protection but face challenges in practical application due to the preparation process and properties.This study develops flake gra...Magnesium potassium phosphate cement(MKPC)coatings exhibit potential for carbon steel protection but face challenges in practical application due to the preparation process and properties.This study develops flake graphite(FG)-modified MKPC coatings via spraying process,investigating the effects of FG size and dosage on phase composition,microstructure,mechanical properties,corrosion protection,and thermal conductivity.Results show that a low FG dosage(5 wt%)synergistically optimizes multifunctional performance.Compared to unmodified MKPC,FG2-1 exhibited exceptional impact resistance,associated with a 57%reduction in corrosion current density(icorr),a 356.3% increase in low-frequency impedance modulus(Z_(0.01 Hz))and a 37% increase in thermal conductivity.However,the coating with a high FG dosage(15 wt%)degraded performance due to defect accumulation and reduced crystallinity of KMgPO_(4)·6H_(2)O.This work advances the rational design of multifunctional inorganic coatings for extreme service environments requiring coupled corrosion protection and thermal management.展开更多
The ternary transition-metal telluride TaCo_(2)Te_(2)has been reported to host a topological band structure characterized by a nontrivial Berry phase.While transport properties have been investigated in both bulk crys...The ternary transition-metal telluride TaCo_(2)Te_(2)has been reported to host a topological band structure characterized by a nontrivial Berry phase.While transport properties have been investigated in both bulk crystals and thick flakes(>150 nm),studies on thin flakes(<100 nm)of this van der Waals(vdW)material remain scarce.We investigate the low-temperature transport properties of TaCo_(2)Te_(2)thin flakes by fabricating Hall bar devices on mechanically exfoliated flakes with different thicknesses(15 nm and 90 nm).Temperature-dependent resistance measurements reveal that the 15-nm-thick sample exhibits a lower residual resistivity ratio and Debye temperature compared to the 90-nm-thick one.Magnetotransport measurements under perpendicular magnetic fields up to±14 T demonstrate lower magnetoresistance,carrier concentration,and mobility in the thinner sample,suggesting increased phonon scattering due to defect-induced disorder.Remarkably,pronounced Shubnikov-de Haas(SdH)oscillations are observed above 8 T in both samples in spite of the defect-induced disorder.Analysis of the Landau fan diagram yields a non-zero Berry phase in both samples,indicating the existence of a topologically non-trivial phase in TaCo_(2)Te_(2)thin flakes.Our findings establish TaCo_(2)Te_(2)as a promising candidate for exploring intrinsic topological states in layered materials.展开更多
In this study,reclaimed asphalt pavement(RAP)used in different percentages in hot mix asphalt(HMA)and warm mix asphalt(WMA)were tested for moisture,fracture and rutting resistance adding hydrogenated castor oil flakes...In this study,reclaimed asphalt pavement(RAP)used in different percentages in hot mix asphalt(HMA)and warm mix asphalt(WMA)were tested for moisture,fracture and rutting resistance adding hydrogenated castor oil flakes(HCOF)as rejuvenating agent.Volumetric and Marshall parameters were evaluated for both types of mixtures.Addition of 5%of HCOF by weight of binder content in RAP found to restore properties of aged binder.WMA mix was made by adding 0.1%Zycotherm by weight of optimum binder content.Moisture,rutting and fracture damage performance were assessed utilizing indirect tensile strength,wheel tracking and semi-circular bending tests.The mix's tensile strength ratio increased by 2.3%in the HMA with RAP(HMA-R)mix compared to the WMA with RAP(WMA-R)mix at 10%RAP content.HMA mixes provide better resistance to rutting compared to WMA.However,40%of RAP content HMA-R and WMA-R using HCOF rejuvenator shows greater rutting performance compared to other RAP mix.HMA-R mix fracture resistance increased by 18.14%compared to WMA-R mix when RAP content increases to 40%.Regression analyses were carried out to validate the strain energy found from fracture damage analysis of both HMA-R and WMA-R with R2 value more than 0.9.HMA-R protected moisture and fracture damage better than WMA-R.The rejuvenating efficiency of HCOF was further validated using Fourier transform infrared and microscopic analysis.展开更多
受全球气候变暖的影响,青藏高原湖泊、河流的温度显著升高,水温变化与水生生物的繁育息息相关,但目前对于青海湖裸鲤洄游产卵的重要场所——河流入湖口的水温研究较少,水温变化对于裸鲤产卵的影响也尚不明确。因此本研究基于刚察气象站...受全球气候变暖的影响,青藏高原湖泊、河流的温度显著升高,水温变化与水生生物的繁育息息相关,但目前对于青海湖裸鲤洄游产卵的重要场所——河流入湖口的水温研究较少,水温变化对于裸鲤产卵的影响也尚不明确。因此本研究基于刚察气象站观测数据、中国区域地面气象要素驱动数据集(CMFD)、欧洲中期天气预报中心第五代陆面再分析数据集(ERA5-Land)、第六次国际耦合模式比较计划(CMIP6)的多模式数据,尝试利用Fresh water Lake Model(简称FLake模式)模拟青海湖最大支流布哈河入湖口处水温并评估其适用性,探讨了再分析数据和CMIP6多模式数据驱动模拟历史(1981—2014年)水温的集合的优越性,预估了未来时期(2024—2100年)三种情景下的水温演变及成因,结果表明:(1)CMFD和ERA5-Land模拟水温的集合优于单个模式的模拟水温且在短期和长期模拟结果精度都较好,CMIP6多模式长期的模拟水温集合优于单个模式的模拟水温,可以较好的再现再分析数据模拟水温的集合。(2)未来布哈河入湖口的水温随着排放强度的增加显著升高,与水温呈正相关的气象因子从大到小依次为气温、比湿、向下长波辐射和向下短波辐射,呈负相关的气象因子是风速;除远期高排放情景(SSP585)的向下短波辐射,其他情景的气象因子与水温的关系均通过了95%的显著性检验。(3)近期(2024—2040年),三种情景的水温较历史时期均有少许升高,水温间的差异不大,青海湖裸鲤产卵的窗口期略微缩短,水温升高会对裸鲤的产卵造成轻微影响;中期(2041—2060年),三种情景的水温进一步升高,水温间的差异逐渐显现,裸鲤的产卵窗口期明显缩短,水温升高对裸鲤的产卵有一定的危害;远期(2081—2100年),三种情景的水温差异更显著,SSP126和SSP245情景的升高速率减慢;SSP585情景的水温升高速率依旧加快,水温持续升高导致裸鲤的产卵窗口期显著缩短,一定程度限制了青海湖裸鲤的产卵活动。展开更多
It is still a challenge to simultaneously enhance coercivity(H_(cj))and remanence(J_(r))of hot-deformed Nd-Fe-B magnet due to the coercivity-remanence trade-off dilemma.Here,we achieved this balance between H_(cj)and ...It is still a challenge to simultaneously enhance coercivity(H_(cj))and remanence(J_(r))of hot-deformed Nd-Fe-B magnet due to the coercivity-remanence trade-off dilemma.Here,we achieved this balance between H_(cj)and Jr by flake Cu powder assisted DyF_(3)interflake addition.The Hcj increases from 1218 to 1496 kA/m and Jr increases from 1.32 to 1.34 T compared with the original magnet.Results show that the width of coarse grain layers reduces because of the introduction of flake Cu,which increases the contact areas of the adjacent grains at ribbon interfaces and suppresses the excessive growth of grains.The stronger degree of texture and higher density compared with the original magnet should take the responsibility for the increase of J_(r).Additionally,the aggregation regions of rare earth rich(RE-rich)phase reduce and the betterment of the microstructure is another reason for the enhancement of Jr in the flake Cu aided DyF_(3)hot-deformed magnet.This strategy of using flake powder additives provides a promising method for optimizing microstructure and enhancing magnetic properties of hot-deformed Nd-Fe-B magnets.展开更多
Deformation behaviors of CNTs/Al alloy composite fabricated by the method of flake powder metallurgy were investigated by hot compression tests, which were performed in the temperature range of 300?550 °C and str...Deformation behaviors of CNTs/Al alloy composite fabricated by the method of flake powder metallurgy were investigated by hot compression tests, which were performed in the temperature range of 300?550 °C and strain rate range of 0.001? 10 s?1 with Gleeble?3500 thermal simulator system. Processing maps of the CNTs/Al alloy at different strains were calculated to study the optimum processing domain. Microstructures before and after hot compressions were characterized by electron backscattered diffraction (EBSD) method. Stress?strain curves indicate that the flow stress increases with the increase of strain rate and the decrease of temperature. The processing maps of the CNTs/Al alloy at different strains show that the optimum processing domain is 500?550 °C, 10 s?1 for hot working. EBSD analysis demonstrates that fully dynamic recrystallization occurs in the optimum processing domain (high strainrate 10 s?1), whereas the main soften mechanism is dynamic recovery at low strain rate (0.001 s?1).展开更多
A novel wet-chemical method for the preparation of silver flakes was studied. The well-defined particles were prepared by directly adding FeSO4 solution into AgNO3 solution containing citric acid at an agitation speed...A novel wet-chemical method for the preparation of silver flakes was studied. The well-defined particles were prepared by directly adding FeSO4 solution into AgNO3 solution containing citric acid at an agitation speed of 150 r/min at room temperature. The products were characterized by scanning electron microscopy （SEM） and X-ray diffraction （XRD）. The results show that particles are irregular thin silver flakes. And the sizes of them range from 2 to 10 μm. It is found that citric acid plays an important role in the formation of sliver flakes. There is an optimum amount of citric acid for the preparation of silver flakes by this method. It is also found that high reduction rate is favorable for the formation of silver flakes.展开更多
The deformation behaviors of Al2O3/Al composites were investigated by compressive tests conducted at temperature of 300-450 °C and strain rates of 0.001-1.0 s-1 with Gleeble-1500 D thermal simulator system. The r...The deformation behaviors of Al2O3/Al composites were investigated by compressive tests conducted at temperature of 300-450 °C and strain rates of 0.001-1.0 s-1 with Gleeble-1500 D thermal simulator system. The results show that the flow stress increases with increasing strain rate and decreasing temperature. The hyperbolic sine constitutive equation can describe the flow stress behavior of Al2O3/Al composites, and the deformation activation energy and constitutive equations were calculated. The processing maps of Al2O3/Al-2 μm and Al2O3/Al-1 μm composites at strain of 0.6 were obtained and the optimum processing domains are in ranges of 300-330 °C, 0.007-0.03 s-1 and 335-360 °C, 0.015-0.06 s-1 for hot working, respectively. The instability zones of flow behavior can also be recognized by the maps.展开更多
In rare cases rolling bearings fail by WEC （white etching crack） damage before reaching their calculated rating life, if so called additional loads are applied on the bearing in addition to the normal Hertzian stre...In rare cases rolling bearings fail by WEC （white etching crack） damage before reaching their calculated rating life, if so called additional loads are applied on the bearing in addition to the normal Hertzian stress （PHz）. A number of additional loads have been identified by means of tests with rolling bearings. These can be small direct currents as a result of electrostatic charge or large alternating currents from inverter-fed drives that unintentionally flow through the bearing. WEC damages can also be initiated by a pure mechanical additional load which is dependent on factors including the bearing kinematics but also on the dynamics of the drive train. The current state of knowledge on this subject is presented and taken as the basis for developing a hypothesis on the WEC damage mechanism. If load situations critical for WEC cannot be avoided, the risk of WEC can be considerably reduced by the selection of suitable materials and coatings as well as, in some cases, of suitable lubricants.展开更多
湖泊对气候变化非常敏感,是气候变化的指示器。青藏高原湖泊众多,但由于观测数据的缺乏,目前对全球变暖背景下高原湖泊热力状况的研究依然不足且多为短期研究。利用中国科学院青藏高原研究所(ITPCAS)开发的中国区域高时空分辨率地面气...湖泊对气候变化非常敏感,是气候变化的指示器。青藏高原湖泊众多,但由于观测数据的缺乏,目前对全球变暖背景下高原湖泊热力状况的研究依然不足且多为短期研究。利用中国科学院青藏高原研究所(ITPCAS)开发的中国区域高时空分辨率地面气象要素驱动数据集、MODIS地表温度数据、青海湖浮标观测数据,分析了Freshwater Lake Model(简称Flake模式)在青海湖的适用性,揭示了青海湖热力状况对气候变化的响应。结果表明,Flake模式能够很好的模拟出青海湖的热力状况,但对夏季与秋季的湖表面水温(特别是夜间)模拟偏高,部分是驱动数据误差造成的,修正驱动数据后模拟效果得到改善。对1989 2012年Flake模拟的湖表面温度与ITPCAS数据不同驱动要素之间的年际变化趋势与相关性进行分析,发现青海湖表面温度呈现上升趋势,与气温、向下长波辐射有较好的正相关性,而与风速负相关。内部热力状况的模拟结果显示,青海湖混合层温度基本全年呈上升趋势,其中5、6月及12月增温最显著;湖泊底层温度在5月以及12月的两次季节性翻转时期呈上升趋势,在6 10月湖水分层期呈下降趋势,分层期湖泊上层温度升高会加强湖水层结稳定性,使湖水混合减弱,导致底层温度下降。展开更多
The mineralogy and petrography of natural graphite in Saba Boru of Ethiopia indicate that there exists flake graphite with a slightly oval structured fine size according to our study on thin and polished sections.Here...The mineralogy and petrography of natural graphite in Saba Boru of Ethiopia indicate that there exists flake graphite with a slightly oval structured fine size according to our study on thin and polished sections.Herein,for estimating the carbon content in graphite,the ASTM-C561,the test method for ash in a graphite sample,was used.For characterizing graphite,x-ray diffraction,x-ray fluorescence,inductively coupled plasma mass spectroscopy,and scanning electron microscopy were also used.Chemical analysis of ore samples determined that the average compositions are 63.35%SiO2,15.45%Al2O3,2.36%Fe2O3,2.07%K2O,less than1%others,and loss-on-ignition(LOI)in the range of^4.74%–37.42%.The total carbon content of graphitic ore ranged from 4.11%to 33.14%.Importantly,when graphite is concentrated through floatation,its average purity and recovery are 92.97%and 90.82%,respectively.Furthermore,once the graphite concentrates are treated with hydrofluoric acid,the average value attains a high grade of 96.48%C.Moreover,the average ash content is 81.93%(pre-flotation)and 3.1%(post-flotation),respectively.Finally,after beneficiation,a silica is identified as a major gangue(85.88%),usable as a raw material for other purposes such as cement.Hence,these graphite-bearing rocks seem to be worth exploring for commercialization opportunities.展开更多
The FTP200 flake tantalum powder was introduced.The microstructures of the powder with leaf-like primary particles having an average flakiness of 2 to 20 and porous agglomerated particles were observed.The chemical co...The FTP200 flake tantalum powder was introduced.The microstructures of the powder with leaf-like primary particles having an average flakiness of 2 to 20 and porous agglomerated particles were observed.The chemical composition,physical properties,and electrical properties of the FTP200 powder were compared with those of the FTW300 nodular powder.The FTP200 powder is more sinter-resistant,and the surface area of the flake tantalum powder under sintering at high temperature has less loss than that of the nodular tantalum powder.The specific capacitance of the flake tantalum powder is higher than that of the nodular tantalum powder with the same surface area when anodized at high voltage.Thus,the flake tantalum powder is suitable for manufacturing tantalum solid electrolytic capacitors in the range of median and high（20-63 V） voltages.展开更多
The use of laser-induced breakdown spectroscopy(LIBS) for the analysis of heavy metals in water samples is investigated. Some factors such as splashing, surface ripples, extinction of emitted intensity, and a shorter ...The use of laser-induced breakdown spectroscopy(LIBS) for the analysis of heavy metals in water samples is investigated. Some factors such as splashing, surface ripples, extinction of emitted intensity, and a shorter plasma lifetime will influence the results if the water sample is directly measured. In order to avoid these disadvantages and the ‘coffee-ring effect', hydrophilic graphite flakes with annular grooves were used for the first time to enrich and concentrate heavy metals in water samples before being analyzed by LIBS. The proposed method and procedure have been evaluated to concentrate and analyze cadmium, chromium, copper, nickel, lead,and zinc in a water sample. The correlation coefficients were all above 0.99. The detection limits of 0.029, 0.087, 0.012, 0.083, 0.125, and 0.049 mgl^(-1) for Cd, Cr, Cu, Ni, Pb, and Zn,respectively, were obtained in samples prepared in a laboratory. With this structure, the heavy metals homogeneously distribute in the annular groove and the relative standard deviations are all below 6%. This method is very convenient and suitable for online in situ analysis of heavy metals.展开更多
一维湖泊模式是青藏高原湖泊研究的主要手段之一,但不同湖泊模式在青藏高原适用性及其差异依然不够明确。利用MODIS地表温度数据、青藏高原鄂陵湖站点观测的气象数据、湖温及湖面能量数据,驱动、评估和对比了目前应用最为广泛的两个一...一维湖泊模式是青藏高原湖泊研究的主要手段之一,但不同湖泊模式在青藏高原适用性及其差异依然不够明确。利用MODIS地表温度数据、青藏高原鄂陵湖站点观测的气象数据、湖温及湖面能量数据,驱动、评估和对比了目前应用最为广泛的两个一维湖泊模式Freshwater Lake Model(FLake)和Community Land Model version 4.5(CLM4.5)中耦合的湖泊模块在青藏高原典型湖泊的适用性。结果表明:FLake和CLM模式均能较好的对湖泊热力状况进行模拟,CLM模式对于湖表面温度和湖泊内部不同深度的温度模拟优于Flake模式,净辐射和能量的累积也是CLM模式的模拟值更接近观测值。造成Flake模式模拟偏差更大的原因与模式中计算感热、潜热的摩擦速度有关,观测的摩擦速度均值为0.22 m·s-1,CLM模式中的摩擦速度与观测值接近,为Flake模式的1.5倍,将CLM模式中的摩擦速度替换到Flake模式中后模拟结果有明显的改善。展开更多
The properties of gray cast iron(GCI)are affected by density of matrix,size of flake graphite and primary austenite.In this paper,the Y-type specimen of GCI was prepared by lost foam casting(LFC)with and without vibra...The properties of gray cast iron(GCI)are affected by density of matrix,size of flake graphite and primary austenite.In this paper,the Y-type specimen of GCI was prepared by lost foam casting(LFC)with and without vibration,and the influence of vibration frequency on the density of matrix,size of primary phase,and properties of the GCI was studied.The results show that the length of the flake graphite and the size of the primary austenite in GCI firstly decrease and then increase with the increase of the vibration frequency.With a vibration frequency of 35 Hz,the length of the flake graphite is the shortest,the primary austenite is the finest and the density of the matrix is the highest.In addition,the tensile strength,elongation and hardness of the GCI firstly increase and then decrease with the increase of the vibration frequency,due to the refinement of the primary phase and the increase of the matrix density.In order to analyze the refinement mechanism of the primary phase of the GCI fabricated by the LFC with vibration,the solidification temperature fields of the GCI fabricated by the LFC with the vibration frequency of 0 and 35 Hz were measured.The results show that the vibration reduces the eutectic point of the GCI and increases the supercooling degree during the eutectic transformation.As a result,the length of the flake graphite and the size of the primary austenite in GCI fabricated by LFC with the vibration frequency of 35 Hz decrease.展开更多
Developing flexible sensors with high working performance holds intense interest for diverse applications in leveraging the Internet-of-things(IoT)infrastructures.For flexible piezoresistive sensors,traditionally most...Developing flexible sensors with high working performance holds intense interest for diverse applications in leveraging the Internet-of-things(IoT)infrastructures.For flexible piezoresistive sensors,traditionally most efforts are focused on tailoring the sensing materials to enhance the contact resistance variation for improving the sensitivity and working range,and it,however,remains challenging to simultaneously achieve flexible sensor with a linear working range over a high-pressure region(>100 kPa)and keep a reliable sensitivity.Herein,we devised a laserengraved silver-coated fabric as"soft"sensor electrode material to markedly advance the flexible sensor's linear working range to a level of 800 kPa with a high sensitivity of 6.4 kPa^-1 yet a fast response time of only 4 ms as well as long-time durability,which was rarely reported before.The integrated sensor successfully routed the wireless signal of pulse rate to the portable smartphone,further demonstrating its potential as a reliable electronic.Along with the rationally building the electrode instead of merely focusing on sensing materials capable of significantly improving the sensor's performance,we expect that this design concept and sensor system could potentially pave the way for developing more advanced wearable electronics in the future.展开更多
基金Supported by Heilongjiang Provincial Scientific Research Project(GC04B509-02)
文摘Flaking on high-moisture corn （wet corn） by hot-air heating was studied in the paper. The wet-heating approach was beneficial to improve corn gelatinization by experimental results. By the experiments, a set of optimal parameters was obtained： hot-air temperature 120-130℃, heating duration 70 min, gap between rollers 0.5 -1.0 mm, 150-200 r·min^-1 for rotational speed of rollers.
基金National Key Research and Development Program of China(2024YFB3714804)National Natural Science Foundation of China(52171277)+1 种基金Baima Lake Laboratory Joint Funds of the Zhejiang Provincial Natural Science Foundation of China(LBMHZ24E020001)Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering(2022SZ-TD006).
文摘Magnesium potassium phosphate cement(MKPC)coatings exhibit potential for carbon steel protection but face challenges in practical application due to the preparation process and properties.This study develops flake graphite(FG)-modified MKPC coatings via spraying process,investigating the effects of FG size and dosage on phase composition,microstructure,mechanical properties,corrosion protection,and thermal conductivity.Results show that a low FG dosage(5 wt%)synergistically optimizes multifunctional performance.Compared to unmodified MKPC,FG2-1 exhibited exceptional impact resistance,associated with a 57%reduction in corrosion current density(icorr),a 356.3% increase in low-frequency impedance modulus(Z_(0.01 Hz))and a 37% increase in thermal conductivity.However,the coating with a high FG dosage(15 wt%)degraded performance due to defect accumulation and reduced crystallinity of KMgPO_(4)·6H_(2)O.This work advances the rational design of multifunctional inorganic coatings for extreme service environments requiring coupled corrosion protection and thermal management.
基金supported by the National Key Research and Development Program of China(Grant Nos.2022YFA1403400 and 2020YFA0309200)the National Natural Science Foundation of China(Grant Nos.12074417,92065203,92365207,and 92477115)+1 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB33000000)the Synergetic Extreme Condition User Facility sponsored by the National Development and Reform Commission,and the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0302600).
文摘The ternary transition-metal telluride TaCo_(2)Te_(2)has been reported to host a topological band structure characterized by a nontrivial Berry phase.While transport properties have been investigated in both bulk crystals and thick flakes(>150 nm),studies on thin flakes(<100 nm)of this van der Waals(vdW)material remain scarce.We investigate the low-temperature transport properties of TaCo_(2)Te_(2)thin flakes by fabricating Hall bar devices on mechanically exfoliated flakes with different thicknesses(15 nm and 90 nm).Temperature-dependent resistance measurements reveal that the 15-nm-thick sample exhibits a lower residual resistivity ratio and Debye temperature compared to the 90-nm-thick one.Magnetotransport measurements under perpendicular magnetic fields up to±14 T demonstrate lower magnetoresistance,carrier concentration,and mobility in the thinner sample,suggesting increased phonon scattering due to defect-induced disorder.Remarkably,pronounced Shubnikov-de Haas(SdH)oscillations are observed above 8 T in both samples in spite of the defect-induced disorder.Analysis of the Landau fan diagram yields a non-zero Berry phase in both samples,indicating the existence of a topologically non-trivial phase in TaCo_(2)Te_(2)thin flakes.Our findings establish TaCo_(2)Te_(2)as a promising candidate for exploring intrinsic topological states in layered materials.
文摘In this study,reclaimed asphalt pavement(RAP)used in different percentages in hot mix asphalt(HMA)and warm mix asphalt(WMA)were tested for moisture,fracture and rutting resistance adding hydrogenated castor oil flakes(HCOF)as rejuvenating agent.Volumetric and Marshall parameters were evaluated for both types of mixtures.Addition of 5%of HCOF by weight of binder content in RAP found to restore properties of aged binder.WMA mix was made by adding 0.1%Zycotherm by weight of optimum binder content.Moisture,rutting and fracture damage performance were assessed utilizing indirect tensile strength,wheel tracking and semi-circular bending tests.The mix's tensile strength ratio increased by 2.3%in the HMA with RAP(HMA-R)mix compared to the WMA with RAP(WMA-R)mix at 10%RAP content.HMA mixes provide better resistance to rutting compared to WMA.However,40%of RAP content HMA-R and WMA-R using HCOF rejuvenator shows greater rutting performance compared to other RAP mix.HMA-R mix fracture resistance increased by 18.14%compared to WMA-R mix when RAP content increases to 40%.Regression analyses were carried out to validate the strain energy found from fracture damage analysis of both HMA-R and WMA-R with R2 value more than 0.9.HMA-R protected moisture and fracture damage better than WMA-R.The rejuvenating efficiency of HCOF was further validated using Fourier transform infrared and microscopic analysis.
文摘受全球气候变暖的影响,青藏高原湖泊、河流的温度显著升高,水温变化与水生生物的繁育息息相关,但目前对于青海湖裸鲤洄游产卵的重要场所——河流入湖口的水温研究较少,水温变化对于裸鲤产卵的影响也尚不明确。因此本研究基于刚察气象站观测数据、中国区域地面气象要素驱动数据集(CMFD)、欧洲中期天气预报中心第五代陆面再分析数据集(ERA5-Land)、第六次国际耦合模式比较计划(CMIP6)的多模式数据,尝试利用Fresh water Lake Model(简称FLake模式)模拟青海湖最大支流布哈河入湖口处水温并评估其适用性,探讨了再分析数据和CMIP6多模式数据驱动模拟历史(1981—2014年)水温的集合的优越性,预估了未来时期(2024—2100年)三种情景下的水温演变及成因,结果表明:(1)CMFD和ERA5-Land模拟水温的集合优于单个模式的模拟水温且在短期和长期模拟结果精度都较好,CMIP6多模式长期的模拟水温集合优于单个模式的模拟水温,可以较好的再现再分析数据模拟水温的集合。(2)未来布哈河入湖口的水温随着排放强度的增加显著升高,与水温呈正相关的气象因子从大到小依次为气温、比湿、向下长波辐射和向下短波辐射,呈负相关的气象因子是风速;除远期高排放情景(SSP585)的向下短波辐射,其他情景的气象因子与水温的关系均通过了95%的显著性检验。(3)近期(2024—2040年),三种情景的水温较历史时期均有少许升高,水温间的差异不大,青海湖裸鲤产卵的窗口期略微缩短,水温升高会对裸鲤的产卵造成轻微影响;中期(2041—2060年),三种情景的水温进一步升高,水温间的差异逐渐显现,裸鲤的产卵窗口期明显缩短,水温升高对裸鲤的产卵有一定的危害;远期(2081—2100年),三种情景的水温差异更显著,SSP126和SSP245情景的升高速率减慢;SSP585情景的水温升高速率依旧加快,水温持续升高导致裸鲤的产卵窗口期显著缩短,一定程度限制了青海湖裸鲤的产卵活动。
基金Project supported by the National Key Research and Development Program of China(2022YFB3505201,2022YFB3505400)the National Natural Science Foundation of China(52261034)the Natural Science Foundation of Jiangxi Province(20224BAB204015)。
文摘It is still a challenge to simultaneously enhance coercivity(H_(cj))and remanence(J_(r))of hot-deformed Nd-Fe-B magnet due to the coercivity-remanence trade-off dilemma.Here,we achieved this balance between H_(cj)and Jr by flake Cu powder assisted DyF_(3)interflake addition.The Hcj increases from 1218 to 1496 kA/m and Jr increases from 1.32 to 1.34 T compared with the original magnet.Results show that the width of coarse grain layers reduces because of the introduction of flake Cu,which increases the contact areas of the adjacent grains at ribbon interfaces and suppresses the excessive growth of grains.The stronger degree of texture and higher density compared with the original magnet should take the responsibility for the increase of J_(r).Additionally,the aggregation regions of rare earth rich(RE-rich)phase reduce and the betterment of the microstructure is another reason for the enhancement of Jr in the flake Cu aided DyF_(3)hot-deformed magnet.This strategy of using flake powder additives provides a promising method for optimizing microstructure and enhancing magnetic properties of hot-deformed Nd-Fe-B magnets.
基金Project(2012AA030311)supported by the National High-tech Research and Development Program of ChinaProject(51421001)supported by the National Natural Science Foundation of ChinaProject(106112015CDJXY130002)supported by the Fundamental Research Funds for the Central Universities,China
文摘Deformation behaviors of CNTs/Al alloy composite fabricated by the method of flake powder metallurgy were investigated by hot compression tests, which were performed in the temperature range of 300?550 °C and strain rate range of 0.001? 10 s?1 with Gleeble?3500 thermal simulator system. Processing maps of the CNTs/Al alloy at different strains were calculated to study the optimum processing domain. Microstructures before and after hot compressions were characterized by electron backscattered diffraction (EBSD) method. Stress?strain curves indicate that the flow stress increases with the increase of strain rate and the decrease of temperature. The processing maps of the CNTs/Al alloy at different strains show that the optimum processing domain is 500?550 °C, 10 s?1 for hot working. EBSD analysis demonstrates that fully dynamic recrystallization occurs in the optimum processing domain (high strainrate 10 s?1), whereas the main soften mechanism is dynamic recovery at low strain rate (0.001 s?1).
基金Project(B20121806)supported by the Science and Technology Research Program of Education Department of Hubei Province,China
文摘A novel wet-chemical method for the preparation of silver flakes was studied. The well-defined particles were prepared by directly adding FeSO4 solution into AgNO3 solution containing citric acid at an agitation speed of 150 r/min at room temperature. The products were characterized by scanning electron microscopy （SEM） and X-ray diffraction （XRD）. The results show that particles are irregular thin silver flakes. And the sizes of them range from 2 to 10 μm. It is found that citric acid plays an important role in the formation of sliver flakes. There is an optimum amount of citric acid for the preparation of silver flakes by this method. It is also found that high reduction rate is favorable for the formation of silver flakes.
基金Project(2012AA030311)supported by the National High-tech Research and Development Program of ChinaProject(2010BB4074)supported by the Natural Science Foundation of Chongqing Municipality,ChinaProject(2010ZD-02)supported by the State Key Laboratory for Advanced Metals and Materials,China
文摘The deformation behaviors of Al2O3/Al composites were investigated by compressive tests conducted at temperature of 300-450 °C and strain rates of 0.001-1.0 s-1 with Gleeble-1500 D thermal simulator system. The results show that the flow stress increases with increasing strain rate and decreasing temperature. The hyperbolic sine constitutive equation can describe the flow stress behavior of Al2O3/Al composites, and the deformation activation energy and constitutive equations were calculated. The processing maps of Al2O3/Al-2 μm and Al2O3/Al-1 μm composites at strain of 0.6 were obtained and the optimum processing domains are in ranges of 300-330 °C, 0.007-0.03 s-1 and 335-360 °C, 0.015-0.06 s-1 for hot working, respectively. The instability zones of flow behavior can also be recognized by the maps.
文摘In rare cases rolling bearings fail by WEC （white etching crack） damage before reaching their calculated rating life, if so called additional loads are applied on the bearing in addition to the normal Hertzian stress （PHz）. A number of additional loads have been identified by means of tests with rolling bearings. These can be small direct currents as a result of electrostatic charge or large alternating currents from inverter-fed drives that unintentionally flow through the bearing. WEC damages can also be initiated by a pure mechanical additional load which is dependent on factors including the bearing kinematics but also on the dynamics of the drive train. The current state of knowledge on this subject is presented and taken as the basis for developing a hypothesis on the WEC damage mechanism. If load situations critical for WEC cannot be avoided, the risk of WEC can be considerably reduced by the selection of suitable materials and coatings as well as, in some cases, of suitable lubricants.
文摘湖泊对气候变化非常敏感,是气候变化的指示器。青藏高原湖泊众多,但由于观测数据的缺乏,目前对全球变暖背景下高原湖泊热力状况的研究依然不足且多为短期研究。利用中国科学院青藏高原研究所(ITPCAS)开发的中国区域高时空分辨率地面气象要素驱动数据集、MODIS地表温度数据、青海湖浮标观测数据,分析了Freshwater Lake Model(简称Flake模式)在青海湖的适用性,揭示了青海湖热力状况对气候变化的响应。结果表明,Flake模式能够很好的模拟出青海湖的热力状况,但对夏季与秋季的湖表面水温(特别是夜间)模拟偏高,部分是驱动数据误差造成的,修正驱动数据后模拟效果得到改善。对1989 2012年Flake模拟的湖表面温度与ITPCAS数据不同驱动要素之间的年际变化趋势与相关性进行分析,发现青海湖表面温度呈现上升趋势,与气温、向下长波辐射有较好的正相关性,而与风速负相关。内部热力状况的模拟结果显示,青海湖混合层温度基本全年呈上升趋势,其中5、6月及12月增温最显著;湖泊底层温度在5月以及12月的两次季节性翻转时期呈上升趋势,在6 10月湖水分层期呈下降趋势,分层期湖泊上层温度升高会加强湖水层结稳定性,使湖水混合减弱,导致底层温度下降。
基金This work was supported by Jimma Institute of Technology through Mega Project.
文摘The mineralogy and petrography of natural graphite in Saba Boru of Ethiopia indicate that there exists flake graphite with a slightly oval structured fine size according to our study on thin and polished sections.Herein,for estimating the carbon content in graphite,the ASTM-C561,the test method for ash in a graphite sample,was used.For characterizing graphite,x-ray diffraction,x-ray fluorescence,inductively coupled plasma mass spectroscopy,and scanning electron microscopy were also used.Chemical analysis of ore samples determined that the average compositions are 63.35%SiO2,15.45%Al2O3,2.36%Fe2O3,2.07%K2O,less than1%others,and loss-on-ignition(LOI)in the range of^4.74%–37.42%.The total carbon content of graphitic ore ranged from 4.11%to 33.14%.Importantly,when graphite is concentrated through floatation,its average purity and recovery are 92.97%and 90.82%,respectively.Furthermore,once the graphite concentrates are treated with hydrofluoric acid,the average value attains a high grade of 96.48%C.Moreover,the average ash content is 81.93%(pre-flotation)and 3.1%(post-flotation),respectively.Finally,after beneficiation,a silica is identified as a major gangue(85.88%),usable as a raw material for other purposes such as cement.Hence,these graphite-bearing rocks seem to be worth exploring for commercialization opportunities.
文摘The FTP200 flake tantalum powder was introduced.The microstructures of the powder with leaf-like primary particles having an average flakiness of 2 to 20 and porous agglomerated particles were observed.The chemical composition,physical properties,and electrical properties of the FTP200 powder were compared with those of the FTW300 nodular powder.The FTP200 powder is more sinter-resistant,and the surface area of the flake tantalum powder under sintering at high temperature has less loss than that of the nodular tantalum powder.The specific capacitance of the flake tantalum powder is higher than that of the nodular tantalum powder with the same surface area when anodized at high voltage.Thus,the flake tantalum powder is suitable for manufacturing tantalum solid electrolytic capacitors in the range of median and high（20-63 V） voltages.
基金supported by National Natural Science Foundation of China (No. 21735005)the Science and Technology Program of Anhui Province (No. 1501041119)+1 种基金the Science and Technology Major Special Program of Anhui Province (No. 15CZZ04125)National Key Research and Development Plan of China (No. 2016YFD0800902-2)
文摘The use of laser-induced breakdown spectroscopy(LIBS) for the analysis of heavy metals in water samples is investigated. Some factors such as splashing, surface ripples, extinction of emitted intensity, and a shorter plasma lifetime will influence the results if the water sample is directly measured. In order to avoid these disadvantages and the ‘coffee-ring effect', hydrophilic graphite flakes with annular grooves were used for the first time to enrich and concentrate heavy metals in water samples before being analyzed by LIBS. The proposed method and procedure have been evaluated to concentrate and analyze cadmium, chromium, copper, nickel, lead,and zinc in a water sample. The correlation coefficients were all above 0.99. The detection limits of 0.029, 0.087, 0.012, 0.083, 0.125, and 0.049 mgl^(-1) for Cd, Cr, Cu, Ni, Pb, and Zn,respectively, were obtained in samples prepared in a laboratory. With this structure, the heavy metals homogeneously distribute in the annular groove and the relative standard deviations are all below 6%. This method is very convenient and suitable for online in situ analysis of heavy metals.
文摘一维湖泊模式是青藏高原湖泊研究的主要手段之一,但不同湖泊模式在青藏高原适用性及其差异依然不够明确。利用MODIS地表温度数据、青藏高原鄂陵湖站点观测的气象数据、湖温及湖面能量数据,驱动、评估和对比了目前应用最为广泛的两个一维湖泊模式Freshwater Lake Model(FLake)和Community Land Model version 4.5(CLM4.5)中耦合的湖泊模块在青藏高原典型湖泊的适用性。结果表明:FLake和CLM模式均能较好的对湖泊热力状况进行模拟,CLM模式对于湖表面温度和湖泊内部不同深度的温度模拟优于Flake模式,净辐射和能量的累积也是CLM模式的模拟值更接近观测值。造成Flake模式模拟偏差更大的原因与模式中计算感热、潜热的摩擦速度有关,观测的摩擦速度均值为0.22 m·s-1,CLM模式中的摩擦速度与观测值接近,为Flake模式的1.5倍,将CLM模式中的摩擦速度替换到Flake模式中后模拟结果有明显的改善。
基金financially supported by the National High Technology Research and Development Program of China(No.2007AA03Z113)
文摘The properties of gray cast iron(GCI)are affected by density of matrix,size of flake graphite and primary austenite.In this paper,the Y-type specimen of GCI was prepared by lost foam casting(LFC)with and without vibration,and the influence of vibration frequency on the density of matrix,size of primary phase,and properties of the GCI was studied.The results show that the length of the flake graphite and the size of the primary austenite in GCI firstly decrease and then increase with the increase of the vibration frequency.With a vibration frequency of 35 Hz,the length of the flake graphite is the shortest,the primary austenite is the finest and the density of the matrix is the highest.In addition,the tensile strength,elongation and hardness of the GCI firstly increase and then decrease with the increase of the vibration frequency,due to the refinement of the primary phase and the increase of the matrix density.In order to analyze the refinement mechanism of the primary phase of the GCI fabricated by the LFC with vibration,the solidification temperature fields of the GCI fabricated by the LFC with the vibration frequency of 0 and 35 Hz were measured.The results show that the vibration reduces the eutectic point of the GCI and increases the supercooling degree during the eutectic transformation.As a result,the length of the flake graphite and the size of the primary austenite in GCI fabricated by LFC with the vibration frequency of 35 Hz decrease.
基金the financial support of the project from the National Natural Science Foundation of China(No.61904141)the funding of Natural Science Foundation of Shaanxi Province(No.2020JQ-295)+3 种基金the Key Research and Development Program of Shaanxi(Program No.2020GY-252)National Key Laboratory of Science and Technology on Vacuum Technology and Physics(HTKJ2019KL510007)City University of Hong Kong(Project Nos.7005070 and 9667153)Shenzhen Science and Technology Innovation Committee under the Grant JCYJ20170818103206501。
文摘Developing flexible sensors with high working performance holds intense interest for diverse applications in leveraging the Internet-of-things(IoT)infrastructures.For flexible piezoresistive sensors,traditionally most efforts are focused on tailoring the sensing materials to enhance the contact resistance variation for improving the sensitivity and working range,and it,however,remains challenging to simultaneously achieve flexible sensor with a linear working range over a high-pressure region(>100 kPa)and keep a reliable sensitivity.Herein,we devised a laserengraved silver-coated fabric as"soft"sensor electrode material to markedly advance the flexible sensor's linear working range to a level of 800 kPa with a high sensitivity of 6.4 kPa^-1 yet a fast response time of only 4 ms as well as long-time durability,which was rarely reported before.The integrated sensor successfully routed the wireless signal of pulse rate to the portable smartphone,further demonstrating its potential as a reliable electronic.Along with the rationally building the electrode instead of merely focusing on sensing materials capable of significantly improving the sensor's performance,we expect that this design concept and sensor system could potentially pave the way for developing more advanced wearable electronics in the future.
