With the rapid growth in electronic device performance,there has been an increasing demand for thermally conductive polymer composites to handle the thermal management issue,thus contributing to the great importance t...With the rapid growth in electronic device performance,there has been an increasing demand for thermally conductive polymer composites to handle the thermal management issue,thus contributing to the great importance to develop the graphene framework,which is evaluated as the most promising reinforcements for enhancing the thermal conductivity of polymer.Vacuum filtration is a common method to fabricate graphene framework,whereas,it is available to prepare a framework with centimeter-scale thickness by filtrating the graphene-water dispersion,due to the fact of sample cracking caused by the mismatch of surface tension between graphene and water.In this work,a surfactantassisted strategy was proposed by adjusting the surface tension of the water close to that of graphene first,then performing a conventional filtration process,to fabricate graphene framework.As a result,a thick graphene framework(thickness:3 cm)was successfully prepared,and after embedding into epoxy,the framework endows the composite(13.6 wt%)with a high in-plane thermal conductivities of12.4 W/mK,which is equivalent to≈64 times higher than that of neat epoxy.Our method is simple and compatible with the conventional filtration process,suggesting great potential for the mass-production of graphene framework to meet the practical application requirements.展开更多
A type of electromagnetic hip-mounted generator （EHG） is proposed to harvest energy from human hip motion to generate electricity. Based on the law of electromagnetic induction, the EHG generator can convert the kin...A type of electromagnetic hip-mounted generator （EHG） is proposed to harvest energy from human hip motion to generate electricity. Based on the law of electromagnetic induction, the EHG generator can convert the kinetic power of the thigh swing into electrical energy during walking or running. To demonstrate the feasibility of the present method, a prototype of the EHG has been designed and fabricated. A theoretical analysis has been conducted to interpret the working behavior of this prototype. In addition, the performance of the system has been experimentally tested through a rotary motor and human body motion. When driven by the rotary motor at a rotation speed of 100 r/rain, the open-circuit voltage of this prototype is 2.5 V. Further, a maximum open-circuit voltage of approximately 1 V and a maximum output power of 284 μW could be produced respectively when walking with an EHG at a speed of 1.47 m/s. This handy renewable energy technology is promising as a pervasive electricity generation system for a group of wearable or implanted sensors, actuators and mobile electronics.展开更多
Navigation with sensor networks has shown many advantages and great potential in many scenarios. Previous works have mainly focused on selecting the shortest path to navigate an internal user out of an emergency field...Navigation with sensor networks has shown many advantages and great potential in many scenarios. Previous works have mainly focused on selecting the shortest path to navigate an internal user out of an emergency field. However, they did not consider variations of the dangerous areas which usually occur in practical applications. This paper presents an efficient dynamic routing algorithm to successfully guide users to the destination exit. The navigation goal is looking for a safe and short path to enable the user to escape from a dangerous area as fast as possible. Without knowing the locations of the nodes, the user is guided by a sequence of sensor nodes to pass through the dangerous areas. The algorithm ensures the navigation path security by predicting the dynamic changes affecting the navigation path. The performance of this approach is evaluated using extensive simulations to validate its effectiveness. Simulations show that the approach is scalable and performs well in various settings.展开更多
With the energy and environmental problems becoming increasingly serious, human power, as a pervasive, renewable, mobile and environment friendly energy, draws more and more attention over the world. In this paper, th...With the energy and environmental problems becoming increasingly serious, human power, as a pervasive, renewable, mobile and environment friendly energy, draws more and more attention over the world. In this paper, the most basic features of human power are presented. The currently available human power harvesting theories and devices are briefly reviewed and compared. Further, direct or indirect utilization of human power in daily life, especially transportation and home appliances, such as human-powered car, watercraft, air- craft, washing machine and television etc. are summarized. Considering that the total energy from an individual is rather limited, as previously focused by most of the former works, it is conceived in this paper that an important future for large scale use of human powers lies in the efficient conversion, collection and storage of such energy from discrete people and then use it later on as desired. With the huge amount of energy gathered, the application category of human power would be significantly expended. Starting from this point, three technical ways towards efficiently utilizing human power are sketched, which are termed as human-powered grid （HPG）, human-powered charger （HPC） and human-powered storage （HPS）, among which, HPG is capable of collecting the electric power produced by each individual at different regions and thus can supply unique and flexible power to the customers covered in the area, without relying on the conventional electricity grid. The HPC can then charge various kinds of electrical devices instantly by a human driven generator which converts human power into electricity. Finally, the HPS can store electricity in time for later use. In this way, even for the devices requiring electricity that is strong enough, the collected human power can also serve as its reliable energy source. Meanwhile, utilization of human power becomes rather convenient and timely which guarantees its practical value. It is expected that with further research and increasing applications, human power could partially relieve the current global electricity shortage and environmental issues via its pervasive contribution.展开更多
A liquid metal magnetohydrodynamics generation system （LMMGS） was proposed and demonstrated in this paper for collecting parasitic power in shoe while walking. Unlike the conventional shoe-mounted human power harves...A liquid metal magnetohydrodynamics generation system （LMMGS） was proposed and demonstrated in this paper for collecting parasitic power in shoe while walking. Unlike the conventional shoe-mounted human power harvesters that use solid coil and gear mechanism, the proposed system employs liquid metal （Ga62In25Sn13） as energy carrier, where no moving part is requested in magnetohydrodynamics generators （MHGs）. While walk- ing with the LMMGS, the foot alternately presses the two liquid metal pumps （LMPs） which are respectively placed in the front and rear of the sole. As a result, the liquid metal in the LMPs （LMP I and II） is extruded and flows through the MHGs （MHG I and II） in which electricity is produced. For a comparison, three types ofLMMGSs （LMMGS A, B and C） were built where all the parts are the same except for the LMPs. Furthermore, performances of these LMMGSs with different volume of injected liquid metal were tested respectively. Experimental results reveal that both the output voltage and power of the LMMGS increase with the volume of injected liquid metal and the size of the LMPs. In addition, a maximum output power of 80 mW is obtained by the LMMGS C with an efficiency of approximately 1.3%. Given its advantages of no side effect, light weight, small size and reliability, The LMMGS is well-suited for powering the wearable and implantable micro/nano device, such as wearable sensors, drug pumps and so on.展开更多
Electronic packaging materials and thermal interface materials(TIMs)are widely used in thermal management.In this study,the epoxy composites with core-shell structure SiC@SiO_(2) nanowires(SiC@SiO_(2) NWs)as fillers c...Electronic packaging materials and thermal interface materials(TIMs)are widely used in thermal management.In this study,the epoxy composites with core-shell structure SiC@SiO_(2) nanowires(SiC@SiO_(2) NWs)as fillers could effectively enhance the thermal conductivity of epoxy composites.The unique structure of fillers results in a high thermal conductivity of epoxy composites,which is attributed to good interfacial compatibility epoxy matrix and bridging connections of SiC@SiO_(2) NWs.From neat epoxy to 2.5 wt%loading of SiC@SiO_(2) NWs,the thermal conductivity is significantly increased from 0.218 to 0.391 W m^(−1) K^(−1),increased by 79.4%.In addition,the composite with 2.5 wt%filler possess lower coefficient of thermal expansion and better thermal stability than that of neat epoxy.All these outstanding properties imply that epoxy/SiC@SiO_(2) NWs composites could be the ideal candidate for TIM.展开更多
The realization of good aqueous dispersibility of commercial graphene products composed of exfoliated graphene sheets is of significance for downstream applications.However,the tap density of commercial graphene powde...The realization of good aqueous dispersibility of commercial graphene products composed of exfoliated graphene sheets is of significance for downstream applications.However,the tap density of commercial graphene powder is quite low(0.03-0.1 kg/m3),meaning that 1 kg graphene powder occupies about 10-30 m3 in volume during transportation.And,the available content of commercial graphene dispersion/slurry in aqueous medium cannot exceed 5 wt%,although the density is high(≈1050 kg/m3).In this work,a graphene monolith was prepared by oven-drying of graphene sheets prefunctionalized with poloxamer surfactants.Our graphene monoliths not only have a high density(1500 kg/m^3) and high graphene content(≈10 wt%),but also a full capability to be completely redispersed(≈100%) in water by bath sonication to obtain solubilized graphene sheets,whose lateral size and thickness are unchanged compared to as-exfoliated ones.Moreover,a simple empirical method was proposed to predict the redispersion capability of graphene monoliths using different poloxamers by contact angle measurements.Our results provide a universal approach to make exfoliated graphene-based products with better downstream availability and lower transportation cost.展开更多
基金financial support by the National Key R&D Program of China (No.2017YFB0406000)Scientific Instrument Developing Project of the Chinese Academy of Sciences (No.YZ201640)+6 种基金the Project of the Chinese Academy of Sciences (No.KFZD-SW-409)Science and Technology Major Project of Ningbo (Nos.2016S1002 and 2016B10038)International S&T Cooperation Program of Ningbo (No. 2017D10016) for financial supportthe Chinese Academy of Sciences for Hundred Talents ProgramChinese Central Government for Thousand Young Talents Program3315 Program of Ningbothe Key Technology of Nuclear Energy (CAS Interdisciplinary Innovation Team,2014)
文摘With the rapid growth in electronic device performance,there has been an increasing demand for thermally conductive polymer composites to handle the thermal management issue,thus contributing to the great importance to develop the graphene framework,which is evaluated as the most promising reinforcements for enhancing the thermal conductivity of polymer.Vacuum filtration is a common method to fabricate graphene framework,whereas,it is available to prepare a framework with centimeter-scale thickness by filtrating the graphene-water dispersion,due to the fact of sample cracking caused by the mismatch of surface tension between graphene and water.In this work,a surfactantassisted strategy was proposed by adjusting the surface tension of the water close to that of graphene first,then performing a conventional filtration process,to fabricate graphene framework.As a result,a thick graphene framework(thickness:3 cm)was successfully prepared,and after embedding into epoxy,the framework endows the composite(13.6 wt%)with a high in-plane thermal conductivities of12.4 W/mK,which is equivalent to≈64 times higher than that of neat epoxy.Our method is simple and compatible with the conventional filtration process,suggesting great potential for the mass-production of graphene framework to meet the practical application requirements.
文摘A type of electromagnetic hip-mounted generator （EHG） is proposed to harvest energy from human hip motion to generate electricity. Based on the law of electromagnetic induction, the EHG generator can convert the kinetic power of the thigh swing into electrical energy during walking or running. To demonstrate the feasibility of the present method, a prototype of the EHG has been designed and fabricated. A theoretical analysis has been conducted to interpret the working behavior of this prototype. In addition, the performance of the system has been experimentally tested through a rotary motor and human body motion. When driven by the rotary motor at a rotation speed of 100 r/rain, the open-circuit voltage of this prototype is 2.5 V. Further, a maximum open-circuit voltage of approximately 1 V and a maximum output power of 284 μW could be produced respectively when walking with an EHG at a speed of 1.47 m/s. This handy renewable energy technology is promising as a pervasive electricity generation system for a group of wearable or implanted sensors, actuators and mobile electronics.
基金Supported by the National Key Basic Research and Development Program (973) of China (No. 2011CB302705)in part by the Zhejiang Agriculture & Forest University Innovation (No. 2009RC11)+1 种基金Science Technology Department of Zhejiang Province Commonwealth (No. 2011C31G2100015)the Zhejiang Provincial Natural Science Foundation (Nos. Y3090558 and Y3100363)
文摘Navigation with sensor networks has shown many advantages and great potential in many scenarios. Previous works have mainly focused on selecting the shortest path to navigate an internal user out of an emergency field. However, they did not consider variations of the dangerous areas which usually occur in practical applications. This paper presents an efficient dynamic routing algorithm to successfully guide users to the destination exit. The navigation goal is looking for a safe and short path to enable the user to escape from a dangerous area as fast as possible. Without knowing the locations of the nodes, the user is guided by a sequence of sensor nodes to pass through the dangerous areas. The algorithm ensures the navigation path security by predicting the dynamic changes affecting the navigation path. The performance of this approach is evaluated using extensive simulations to validate its effectiveness. Simulations show that the approach is scalable and performs well in various settings.
文摘With the energy and environmental problems becoming increasingly serious, human power, as a pervasive, renewable, mobile and environment friendly energy, draws more and more attention over the world. In this paper, the most basic features of human power are presented. The currently available human power harvesting theories and devices are briefly reviewed and compared. Further, direct or indirect utilization of human power in daily life, especially transportation and home appliances, such as human-powered car, watercraft, air- craft, washing machine and television etc. are summarized. Considering that the total energy from an individual is rather limited, as previously focused by most of the former works, it is conceived in this paper that an important future for large scale use of human powers lies in the efficient conversion, collection and storage of such energy from discrete people and then use it later on as desired. With the huge amount of energy gathered, the application category of human power would be significantly expended. Starting from this point, three technical ways towards efficiently utilizing human power are sketched, which are termed as human-powered grid （HPG）, human-powered charger （HPC） and human-powered storage （HPS）, among which, HPG is capable of collecting the electric power produced by each individual at different regions and thus can supply unique and flexible power to the customers covered in the area, without relying on the conventional electricity grid. The HPC can then charge various kinds of electrical devices instantly by a human driven generator which converts human power into electricity. Finally, the HPS can store electricity in time for later use. In this way, even for the devices requiring electricity that is strong enough, the collected human power can also serve as its reliable energy source. Meanwhile, utilization of human power becomes rather convenient and timely which guarantees its practical value. It is expected that with further research and increasing applications, human power could partially relieve the current global electricity shortage and environmental issues via its pervasive contribution.
文摘A liquid metal magnetohydrodynamics generation system （LMMGS） was proposed and demonstrated in this paper for collecting parasitic power in shoe while walking. Unlike the conventional shoe-mounted human power harvesters that use solid coil and gear mechanism, the proposed system employs liquid metal （Ga62In25Sn13） as energy carrier, where no moving part is requested in magnetohydrodynamics generators （MHGs）. While walk- ing with the LMMGS, the foot alternately presses the two liquid metal pumps （LMPs） which are respectively placed in the front and rear of the sole. As a result, the liquid metal in the LMPs （LMP I and II） is extruded and flows through the MHGs （MHG I and II） in which electricity is produced. For a comparison, three types ofLMMGSs （LMMGS A, B and C） were built where all the parts are the same except for the LMPs. Furthermore, performances of these LMMGSs with different volume of injected liquid metal were tested respectively. Experimental results reveal that both the output voltage and power of the LMMGS increase with the volume of injected liquid metal and the size of the LMPs. In addition, a maximum output power of 80 mW is obtained by the LMMGS C with an efficiency of approximately 1.3%. Given its advantages of no side effect, light weight, small size and reliability, The LMMGS is well-suited for powering the wearable and implantable micro/nano device, such as wearable sensors, drug pumps and so on.
基金The authors are grateful for the financial support by the National Natural Science Foundation of China(51573201 and 51303034)Public Welfare Project of Zhejiang Province(2016C31026)International S&T Cooperation Program of Ningbo(2015D10003)。
文摘Electronic packaging materials and thermal interface materials(TIMs)are widely used in thermal management.In this study,the epoxy composites with core-shell structure SiC@SiO_(2) nanowires(SiC@SiO_(2) NWs)as fillers could effectively enhance the thermal conductivity of epoxy composites.The unique structure of fillers results in a high thermal conductivity of epoxy composites,which is attributed to good interfacial compatibility epoxy matrix and bridging connections of SiC@SiO_(2) NWs.From neat epoxy to 2.5 wt%loading of SiC@SiO_(2) NWs,the thermal conductivity is significantly increased from 0.218 to 0.391 W m^(−1) K^(−1),increased by 79.4%.In addition,the composite with 2.5 wt%filler possess lower coefficient of thermal expansion and better thermal stability than that of neat epoxy.All these outstanding properties imply that epoxy/SiC@SiO_(2) NWs composites could be the ideal candidate for TIM.
基金financial support by the National Natural Science Foundation of China(Nos.51573201,51501209 and 201675165)NSFC-Zhejiang Joint Fund for the Integration of Industrialization and Informatization(No.U1709205)+6 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA22000000)Scientific Instrument Developing Project of the Chinese Academy of Sciences(No.YZ201640)Science and Technology Major Project of Ningbo(Nos.2016S1002 and 2016B10038)International S&T Cooperation Program of Ningbo(No.2017D10016)for financial supportthe Chinese Academy of Sciences for Hundred Talents ProgramChinese Central Government for Thousand Young Talents Program3315 Program of Ningbo。
文摘The realization of good aqueous dispersibility of commercial graphene products composed of exfoliated graphene sheets is of significance for downstream applications.However,the tap density of commercial graphene powder is quite low(0.03-0.1 kg/m3),meaning that 1 kg graphene powder occupies about 10-30 m3 in volume during transportation.And,the available content of commercial graphene dispersion/slurry in aqueous medium cannot exceed 5 wt%,although the density is high(≈1050 kg/m3).In this work,a graphene monolith was prepared by oven-drying of graphene sheets prefunctionalized with poloxamer surfactants.Our graphene monoliths not only have a high density(1500 kg/m^3) and high graphene content(≈10 wt%),but also a full capability to be completely redispersed(≈100%) in water by bath sonication to obtain solubilized graphene sheets,whose lateral size and thickness are unchanged compared to as-exfoliated ones.Moreover,a simple empirical method was proposed to predict the redispersion capability of graphene monoliths using different poloxamers by contact angle measurements.Our results provide a universal approach to make exfoliated graphene-based products with better downstream availability and lower transportation cost.
