A numerical analysis is presented for the oscillatory flow of Maxwell fluid in a rectangular straight duct subjected to a simple harmonic periodic pressure gradient.The numerical solutions are obtained by a finite dif...A numerical analysis is presented for the oscillatory flow of Maxwell fluid in a rectangular straight duct subjected to a simple harmonic periodic pressure gradient.The numerical solutions are obtained by a finite difference scheme method.The stability of this finite difference scheme method is discussed.The distributions of the velocity and phase difference are given numerically and graphically.The effects of the Reynolds number,relaxation time,and aspect ratio of the cross section on the oscillatory flow are investigated.The results show that when the relaxation time of the Maxwell model and the Reynolds number increase,the resonance phenomena for the distributions of the velocity and phase difference enhance.展开更多
Water-triggered materials are receiving increasing attentions due to their diverse capabilities such as easy operation,soft actuation,low cost,environmental friendliness,and many more other advantages.However,most of ...Water-triggered materials are receiving increasing attentions due to their diverse capabilities such as easy operation,soft actuation,low cost,environmental friendliness,and many more other advantages.However,most of such materials generally have a long reaction time and require strict preservation conditions,which limit their adaptability in practice.In this study,a novel water-triggered material based on Al-NaOH-composited eutectic gallium–indium(eGaIn)alloys was proposed and demonstrated,which is rather fast-responsive and deformable.Once water is applied,the material thus fabricated would achieve a temperature rise of 40C in just several seconds along with gas production,indicating its big potential to be used as a thermal and pneumatic actuator.Further,the new material’s reusability and degradation ability were also tested.Following that,a double-layer-structure smart bandage was designed,whose bulk was filled with Al-NaOH-composited eGaIn while BiInSn served as outer supporting material.According to the experiments,a sheet structure with a thickness of 2 mm would support a weight of 1.8 kg after it was subjected to a cooling process,which is much better than the weight-bearing capability of fiberglass.In addition,a prototype of a water-triggered sphere robot was also fabricated using Al-NaOH-eGaIn,which realized rolling and bouncing behaviors under specific external stimulation.These findings indicate the potential value of the present material in developing future wearable devices,soft actuators,and soft robotics.展开更多
Drying is a key step in starch noodle production.The effects of high temperature(60,70,80°C)and high relative humidity(65%,75%,85%)drying(HTHD)on the moisture distribution,starch microstructure and cooking charac...Drying is a key step in starch noodle production.The effects of high temperature(60,70,80°C)and high relative humidity(65%,75%,85%)drying(HTHD)on the moisture distribution,starch microstructure and cooking characteristics of extruded whole buckwheat noodles were investigated.Compared to the conventional hot-air drying(CHAD)at 40°C,the increase in drying temperature(60–80°C)and the decrease in relative humidity(85%–65%)significantly improved drying efficiency of the extruded noodles.By adjusting drying temperature and relative humidity,the rate of moisture migration in noodles and phase transition of starch could be appropriately controlled.The optimum drying parameters(T70H75,70°C drying temperature and 75%relative humidity)showed smooth and dense network structure,resulting in the lowest cooking loss(6.61%),broken rate(0%),highest hardness(1695.17 g)and springiness(0.92).However,the total flavonoid content(TFC)and the total phenolic content(TPC)reduced by 6.81%–28.50%and 7.19%–53.23%in contrast to CHAD,and the color of buckwheat noodles became darker through HTHD.These findings showed the potential of HTHD for increasing drying efficiency and improving buckwheat noodle quality.The appropriate drying parameters could maintain a balanced relationship between moisture migration in noodles and phase transition of starch,which resulted in better cooking quality for extruded whole buckwheat noodles.Such a study is valuable for regulating the process conditions of buckwheat-based foods and promoting its commercial utilization.展开更多
CONSPECTUS:Conventional robots can accomplish defined tasks but often encounter troubles when handling irregular objects under unstructured environments.Soft robots,with supercompliance,large transformation,and high e...CONSPECTUS:Conventional robots can accomplish defined tasks but often encounter troubles when handling irregular objects under unstructured environments.Soft robots,with supercompliance,large transformation,and high environmental adaptability,hold big promise for delicate manipulations such as grasping soft objects or delivering precious biomedical samples.Even a step further,if soft robots are endowed with the extraordinary behaviors to freely transform among different morphologies and constructions just like those already existing in literature and science fiction films,more fantastic challenges can be tackled.Representing one of the most potential robotic soft materials,liquid metals have been given sufficient expectations on realizing the transformable machines that might fundamentally reform modern daily life.Accordingly,inspiring discoveries on controllable transformations of the liquid metal have been obtained surprisingly and tremendous efforts have been made over the past decade,indicating a significant step toward such a formidable dream.It is clear that the discovery of liquid metal-based largescaled transformation with several hundred-fold fast change on the surface area opens a brand new direction of manufacturing future transformable machines.Even unusual findings on a self-fueled liquid metal with biological life-like behavior to freely explore the unknown space that solves the energy supply issue also came into being,holding big promise for making bionic transformable robots.This Account aims to systematically sort out the developmental history of liquid metal transformable machines with special focus on the fundamental scientific discoveries,the underlying mechanisms,and the potential applied scenarios based on liquid metal enabled solid−liquid hybrids.The fantastic properties and unique transformation capabilities of liquid metals have built the basis for a new era of designing soft robotics and we believe that liquid metal transformable machines are evolving into new forms of soft robots.展开更多
基金Project supported by the National Natural Science Foundation of China(Nos.11672164 and41831278)the Taishan Scholars Project Foundation of Shandong Province of China
文摘A numerical analysis is presented for the oscillatory flow of Maxwell fluid in a rectangular straight duct subjected to a simple harmonic periodic pressure gradient.The numerical solutions are obtained by a finite difference scheme method.The stability of this finite difference scheme method is discussed.The distributions of the velocity and phase difference are given numerically and graphically.The effects of the Reynolds number,relaxation time,and aspect ratio of the cross section on the oscillatory flow are investigated.The results show that when the relaxation time of the Maxwell model and the Reynolds number increase,the resonance phenomena for the distributions of the velocity and phase difference enhance.
基金the Key Program of National Natural Science foundation of China(91748206)。
文摘Water-triggered materials are receiving increasing attentions due to their diverse capabilities such as easy operation,soft actuation,low cost,environmental friendliness,and many more other advantages.However,most of such materials generally have a long reaction time and require strict preservation conditions,which limit their adaptability in practice.In this study,a novel water-triggered material based on Al-NaOH-composited eutectic gallium–indium(eGaIn)alloys was proposed and demonstrated,which is rather fast-responsive and deformable.Once water is applied,the material thus fabricated would achieve a temperature rise of 40C in just several seconds along with gas production,indicating its big potential to be used as a thermal and pneumatic actuator.Further,the new material’s reusability and degradation ability were also tested.Following that,a double-layer-structure smart bandage was designed,whose bulk was filled with Al-NaOH-composited eGaIn while BiInSn served as outer supporting material.According to the experiments,a sheet structure with a thickness of 2 mm would support a weight of 1.8 kg after it was subjected to a cooling process,which is much better than the weight-bearing capability of fiberglass.In addition,a prototype of a water-triggered sphere robot was also fabricated using Al-NaOH-eGaIn,which realized rolling and bouncing behaviors under specific external stimulation.These findings indicate the potential value of the present material in developing future wearable devices,soft actuators,and soft robotics.
文摘Drying is a key step in starch noodle production.The effects of high temperature(60,70,80°C)and high relative humidity(65%,75%,85%)drying(HTHD)on the moisture distribution,starch microstructure and cooking characteristics of extruded whole buckwheat noodles were investigated.Compared to the conventional hot-air drying(CHAD)at 40°C,the increase in drying temperature(60–80°C)and the decrease in relative humidity(85%–65%)significantly improved drying efficiency of the extruded noodles.By adjusting drying temperature and relative humidity,the rate of moisture migration in noodles and phase transition of starch could be appropriately controlled.The optimum drying parameters(T70H75,70°C drying temperature and 75%relative humidity)showed smooth and dense network structure,resulting in the lowest cooking loss(6.61%),broken rate(0%),highest hardness(1695.17 g)and springiness(0.92).However,the total flavonoid content(TFC)and the total phenolic content(TPC)reduced by 6.81%–28.50%and 7.19%–53.23%in contrast to CHAD,and the color of buckwheat noodles became darker through HTHD.These findings showed the potential of HTHD for increasing drying efficiency and improving buckwheat noodle quality.The appropriate drying parameters could maintain a balanced relationship between moisture migration in noodles and phase transition of starch,which resulted in better cooking quality for extruded whole buckwheat noodles.Such a study is valuable for regulating the process conditions of buckwheat-based foods and promoting its commercial utilization.
基金partially supported by the National Natural Science Foundation of China Key Project (91748206)Dean’s Research Funding and the Frontier Project of the Chinese Academy of Sciences
基金This work was supported by the National Nature Science Foundation of China under Key Project(51890893,52106066,81701850,and 91748206)Shuimu Tsinghua Scholarship,China Postdoctoral Science Foundation(2021M691707)the Fundamental Research Funds for the Central Universities(YWF-21-BJ-J-1170).
文摘CONSPECTUS:Conventional robots can accomplish defined tasks but often encounter troubles when handling irregular objects under unstructured environments.Soft robots,with supercompliance,large transformation,and high environmental adaptability,hold big promise for delicate manipulations such as grasping soft objects or delivering precious biomedical samples.Even a step further,if soft robots are endowed with the extraordinary behaviors to freely transform among different morphologies and constructions just like those already existing in literature and science fiction films,more fantastic challenges can be tackled.Representing one of the most potential robotic soft materials,liquid metals have been given sufficient expectations on realizing the transformable machines that might fundamentally reform modern daily life.Accordingly,inspiring discoveries on controllable transformations of the liquid metal have been obtained surprisingly and tremendous efforts have been made over the past decade,indicating a significant step toward such a formidable dream.It is clear that the discovery of liquid metal-based largescaled transformation with several hundred-fold fast change on the surface area opens a brand new direction of manufacturing future transformable machines.Even unusual findings on a self-fueled liquid metal with biological life-like behavior to freely explore the unknown space that solves the energy supply issue also came into being,holding big promise for making bionic transformable robots.This Account aims to systematically sort out the developmental history of liquid metal transformable machines with special focus on the fundamental scientific discoveries,the underlying mechanisms,and the potential applied scenarios based on liquid metal enabled solid−liquid hybrids.The fantastic properties and unique transformation capabilities of liquid metals have built the basis for a new era of designing soft robotics and we believe that liquid metal transformable machines are evolving into new forms of soft robots.
