To improve the deteriorated capacity gain and source recovery performance due to channel mismatch problem,this paper reports a research about blind separation method against channel mismatch in multiple-input multiple...To improve the deteriorated capacity gain and source recovery performance due to channel mismatch problem,this paper reports a research about blind separation method against channel mismatch in multiple-input multiple-output(MIMO) systems.The channel mismatch problem can be described as a channel with bounded fluctuant errors due to channel distortion or channel estimation errors.The problem of blind signal separation/extraction with channel mismatch is formulated as a cost function of blind source separation(BSS) subject to the second-order cone constraint,which can be called as second-order cone programing optimization problem.Then the resulting cost function is solved by approximate negentropy maximization using quasi-Newton iterative methods for blind separation/extraction source signals.Theoretical analysis demonstrates that the proposed algorithm has low computational complexity and improved performance advantages.Simulation results verify that the capacity gain and bit error rate(BER) performance of the proposed blind separation method is superior to those of the existing methods in MIMO systems with channel mismatch problem.展开更多
The rapid evolution of laser micro/nano-manufacturing techniques has transformed precision manufacturing,enabling the creation of complex micro/nano-structures.These techniques are crucial for multiple industries,incl...The rapid evolution of laser micro/nano-manufacturing techniques has transformed precision manufacturing,enabling the creation of complex micro/nano-structures.These techniques are crucial for multiple industries,including electronics,photonics,and biomedical engineering,owing to their unmatched precision and versatility.The ability to manipulate materials at such scales has unlocked new possibilities for innovation,thereby facilitating the development of advanced components and devices with enhanced performance and functionalities.展开更多
该研究旨在分析不同产区修水宁红茶的香气组分及感官品质差异,探讨产区对其品质的影响。采用顶空固相微萃取-气相色谱-质谱联用技术(headspace solid-phase microextraction and gas chromatography mass spectrometry,HS-SPME-GC-MS)分...该研究旨在分析不同产区修水宁红茶的香气组分及感官品质差异,探讨产区对其品质的影响。采用顶空固相微萃取-气相色谱-质谱联用技术(headspace solid-phase microextraction and gas chromatography mass spectrometry,HS-SPME-GC-MS)分析3个产区的修水宁红茶香气组分,并运用主成分分析(principal component analysis,PCA)和偏最小二乘判别分析(partial least squares discrimination analysis,PLS-DA)评估产区对香气组分的影响,结合偏最小二乘回归变量投影重要性(variable importance in projection,VIP)分析、单因素方差分析(P<0.05)以及计算气味活性值(odor activity value,OAV)确定关键香气组分。共鉴定出99种香气组分,包括醇类、醛类、酮类、酯类、萜烯类、烷烃类和酸类。PCA和PLS-DA表明,产区对修水宁红茶的香气组分具有显著影响。结合VIP分析,共筛选出22种VIP值大于1的香气组分,通过方差分析进一步筛选出8种香气组分,确定了(E)-3-己烯-1-醇、(E)-呋喃芳樟醇氧化物、δ-杜松烯、正己醛、(Z)-3-己烯己酸酯和苯甲醇是修水宁红茶的关键呈香物质。该研究揭示了产区对修水宁红茶香气组分的显著影响,确定了关键呈香物质,明确了其对感官品质的贡献,为修水宁红茶的香味调控和品质提升提供了科学依据和研究基础。展开更多
Multidimensional integration and multifunctional com-ponent assembly have been greatly explored in recent years to extend Moore’s Law of modern microelectronics.However,this inevitably exac-erbates the inhomogeneity ...Multidimensional integration and multifunctional com-ponent assembly have been greatly explored in recent years to extend Moore’s Law of modern microelectronics.However,this inevitably exac-erbates the inhomogeneity of temperature distribution in microsystems,making precise temperature control for electronic components extremely challenging.Herein,we report an on-chip micro temperature controller including a pair of thermoelectric legs with a total area of 50×50μm^(2),which are fabricated from dense and flat freestanding Bi2Te3-based ther-moelectric nano films deposited on a newly developed nano graphene oxide membrane substrate.Its tunable equivalent thermal resistance is controlled by electrical currents to achieve energy-efficient temperature control for low-power electronics.A large cooling temperature difference of 44.5 K at 380 K is achieved with a power consumption of only 445μW,resulting in an ultrahigh temperature control capability over 100 K mW^(-1).Moreover,an ultra-fast cooling rate exceeding 2000 K s^(-1) and excellent reliability of up to 1 million cycles are observed.Our proposed on-chip temperature controller is expected to enable further miniaturization and multifunctional integration on a single chip for microelectronics.展开更多
In this work, a rumor’s spreading and controlling in a directed Micro-blog user network being consisted with 580 000 nodes are simulated. By defining some authority nodes that release anti-rumor information as the pr...In this work, a rumor’s spreading and controlling in a directed Micro-blog user network being consisted with 580 000 nodes are simulated. By defining some authority nodes that release anti-rumor information as the prevention strategy, the effect of the nodes’ role in network on rumor’s suppression is studied. The findings show that rumor will be spread out fast and reach a stable level within limited steps. The suppression of rumor is more predominated by the intervening opportunity, the earlier the intervention strategy was implemented, the better the rumor’s controlling could be achieved. The controlling effect is less relevant with the role of the authority nodes in network.展开更多
The NIR micro-images of ibuprofen tablets were collected in this research.Compare correlation imaging and principal component analysis（PC A） with histogram were applied to acquire the spatial distribution of ibuprof...The NIR micro-images of ibuprofen tablets were collected in this research.Compare correlation imaging and principal component analysis（PC A） with histogram were applied to acquire the spatial distribution of ibuprofen granule.The result indicated that a similar distribution trend can be acquired by both of the two methods mentioned above;the information of PC2 results from ibuprofen mainly since the correlation coefficient between PC2 loading vector and the NIR spectrum of ibuprofen is 0.9930.The result of PCA indicated that the information of PC2 results from ibuprofen mainly for both the low and the high content of ibuprofen in the tablets.The correlation coefficient between the data of the two PC2 loading vectors of the low and the high content of ibuprofen in the tablets is 0.9998,which indicates that the result of PCA is stable and reliable.展开更多
Excellent fluid sealing performance is crucial to ensuring the safety of important equipment,especially in aerospace field,such as space capsule and fuel chamber.The frequently opening and closing of the sealing devic...Excellent fluid sealing performance is crucial to ensuring the safety of important equipment,especially in aerospace field,such as space capsule and fuel chamber.The frequently opening and closing of the sealing devices is particularly important.Driven by this background,clams(Mactra chinensis)which can open and close their double shells with superior sealing performance,are studied in this work.Here,we show that the clam’s sealing ability is the result of its unique multilevel intermeshing microstructures,including hinge teeth and micro-blocks.These microstructures,which resemble gear teeth,engage with each other when the shell closes,forming a tight structure that prevents the infiltration of water from the outside.Furthermore,the presence of micron blocks prevents the penetration of finer liquids.The simulation results of the bionic end seal components show that the multilevel microstructure has a superior sealing effect.This research is expected to be applied to undersea vehicles that require frequent door opening and closing.展开更多
Due to the rise of biological and MEMS technology in recent years, some micro flow system components have drawn attention and been developed by many investigators. The importance of micro-pumps manufactured is higher ...Due to the rise of biological and MEMS technology in recent years, some micro flow system components have drawn attention and been developed by many investigators. The importance of micro-pumps manufactured is higher than the other part of micro flow system since it is the power source of the entire micro-flow system and responsible for driving working fluid in the microfluidic system. In actual operation, the instability and bad dynamic characteristics of the micro-pump will cause larger fluid flow mobility error, such as transport behavior and response procedures failure, etc., and even damage the microfluidic system. Therefore, to investigate the stability and dynamic characteristics of a micro pump is necessary. The Finite element analysis (FEA), ANSYS Workbench, is employed to analyze the dynamic characteristics of this micro pump, and experiment is also considered in this study.展开更多
The influences of micro alloy and heat treatment procedure on the hardening of DJ108Ti alloy, which is based on the electrolytic Al Si(2 05%) Ti(0 25%) Fe(0 30%) multi component alloy, have been investigated...The influences of micro alloy and heat treatment procedure on the hardening of DJ108Ti alloy, which is based on the electrolytic Al Si(2 05%) Ti(0 25%) Fe(0 30%) multi component alloy, have been investigated. The results indicate that the micro alloy based on the multi component alloy makes α Al dendrites in DJ108Ti alloy refined; that the improved heat treatment procedure makes the eutectic Si phases granulated , the Fe phase refined, and the strengthening phases of Mg2Si and Al2Cu fully precipitated. The micro alloy and the heat treatment procedure harden DJ108Ti alloy and benefit the abrasion resistance of the alloy展开更多
This research focused on integrating GIS into energy alternatives for climate change mitigation by creating a GIS-based hydrologic model that can be used to identify sites that have significant potential for micro hyd...This research focused on integrating GIS into energy alternatives for climate change mitigation by creating a GIS-based hydrologic model that can be used to identify sites that have significant potential for micro hydropower development within the River Perkerra catchment area. Hydropower is a clean and renewable energy source that remains largely untapped in the country and its development can be used to mitigate anthropogenic climate change by reducing reliance on fossil or biomass derived fuels. This research established the extent of this resource and whether the available sites with significant micro hydropower potential within the study area were amply copious to warrant further development. Currently, such identification is done physically using means that are menial, costly and significantly time consuming. A 90-metre resolution Digital Terrain Model (DTM) data obtained from the Shuttle Radar Topography Mission and various GIS tools were used to create a hydrologic framework which was used to identify potential sites along River Perkerra that suited any desired head requirement for the purposes of locating micro hydropower plants. The derived model demonstrated that it was possible to identify sites at discrete geographic locations along any stream drainage network using GIS. In addition, the model also provides a decision support system that integrates a powerful graphical user interface, spatial database management system and a generalized river basin network flow model for the purposes of exploiting and developing micro hydropower. With sufficient data on catchment discharge and use of higher resolution DTM, the model can be further enhanced to accurately obtain the total microhydro potential of River Perkerra by aggregating the respective potentials of every steam segment.展开更多
The ever increasing development of portable electronics has led to a higher demand for compact and reliable power sources. Significant resources are being presently dedicated to the study of micro machined gas turbine...The ever increasing development of portable electronics has led to a higher demand for compact and reliable power sources. Significant resources are being presently dedicated to the study of micro machined gas turbines, because of their remarkable power density. The paper reports the procedures and the results of a series of tests conducted at the Department of Mechanical & Aerospace Engineering of University of Roma 1, to obtain the map of an ultra-micro gas turbine device, and the head losses and the combustion efficiency of the corresponding ultra-micro combustion chamber, fed by a mixture of butane and propane. This work is a part of a research aimed at the conception, design and prototyping of an ultra-micro thermo-electrical device for portable power generation. The novelty of the research consists in the fact that the thermal engine is a (ultra-micro) gas turbine set. In a subsequent stage, several different configurations have been assessed to select the most proper geometry and structural characteristics of the most relevant components (radial compressor, radial turbine, combustion chamber, electric motor and generator, bearings, regenerative heat exchanger).展开更多
基金supported by Sichuan Youth Science and Technology Innovation Research Team Project(No.2015TD0022)the Talents Project of Sichuan University of Science and Engineering(No.2017RCL11 and No.2017RCL10)the first batch of science and technology plan key R&D project of Sichuan province(No.2017GZ0068)
文摘To improve the deteriorated capacity gain and source recovery performance due to channel mismatch problem,this paper reports a research about blind separation method against channel mismatch in multiple-input multiple-output(MIMO) systems.The channel mismatch problem can be described as a channel with bounded fluctuant errors due to channel distortion or channel estimation errors.The problem of blind signal separation/extraction with channel mismatch is formulated as a cost function of blind source separation(BSS) subject to the second-order cone constraint,which can be called as second-order cone programing optimization problem.Then the resulting cost function is solved by approximate negentropy maximization using quasi-Newton iterative methods for blind separation/extraction source signals.Theoretical analysis demonstrates that the proposed algorithm has low computational complexity and improved performance advantages.Simulation results verify that the capacity gain and bit error rate(BER) performance of the proposed blind separation method is superior to those of the existing methods in MIMO systems with channel mismatch problem.
文摘The rapid evolution of laser micro/nano-manufacturing techniques has transformed precision manufacturing,enabling the creation of complex micro/nano-structures.These techniques are crucial for multiple industries,including electronics,photonics,and biomedical engineering,owing to their unmatched precision and versatility.The ability to manipulate materials at such scales has unlocked new possibilities for innovation,thereby facilitating the development of advanced components and devices with enhanced performance and functionalities.
文摘该研究旨在分析不同产区修水宁红茶的香气组分及感官品质差异,探讨产区对其品质的影响。采用顶空固相微萃取-气相色谱-质谱联用技术(headspace solid-phase microextraction and gas chromatography mass spectrometry,HS-SPME-GC-MS)分析3个产区的修水宁红茶香气组分,并运用主成分分析(principal component analysis,PCA)和偏最小二乘判别分析(partial least squares discrimination analysis,PLS-DA)评估产区对香气组分的影响,结合偏最小二乘回归变量投影重要性(variable importance in projection,VIP)分析、单因素方差分析(P<0.05)以及计算气味活性值(odor activity value,OAV)确定关键香气组分。共鉴定出99种香气组分,包括醇类、醛类、酮类、酯类、萜烯类、烷烃类和酸类。PCA和PLS-DA表明,产区对修水宁红茶的香气组分具有显著影响。结合VIP分析,共筛选出22种VIP值大于1的香气组分,通过方差分析进一步筛选出8种香气组分,确定了(E)-3-己烯-1-醇、(E)-呋喃芳樟醇氧化物、δ-杜松烯、正己醛、(Z)-3-己烯己酸酯和苯甲醇是修水宁红茶的关键呈香物质。该研究揭示了产区对修水宁红茶香气组分的显著影响,确定了关键呈香物质,明确了其对感官品质的贡献,为修水宁红茶的香味调控和品质提升提供了科学依据和研究基础。
基金The authors thank D.Berger,D.Hofmann and C.Kupka in IFW Dresden for helpful technical support.H.R.acknowledges funding from the DFG(Deutsche Forschungsgemeinschaft)within grant number RE3973/1-1.Q.J.,H.R.and K.N.conceived the work.With the support from N.Y.and X.J.,Q.J.and T.G.fabricated the thermoelectric films and conducted the structural and compositional characterizations.Q.J.prepared microchips and fabricated the on-chip micro temperature controllers.Q.J.and N.P.carried out the temperature-dependent material and device performance measurements.Q.J.and H.R.performed the simulation and analytical calculations.Q.J.,H.R.and K.N.wrote the manuscript with input from the other coauthors.All the authors discussed the results and commented on the manuscript.
文摘Multidimensional integration and multifunctional com-ponent assembly have been greatly explored in recent years to extend Moore’s Law of modern microelectronics.However,this inevitably exac-erbates the inhomogeneity of temperature distribution in microsystems,making precise temperature control for electronic components extremely challenging.Herein,we report an on-chip micro temperature controller including a pair of thermoelectric legs with a total area of 50×50μm^(2),which are fabricated from dense and flat freestanding Bi2Te3-based ther-moelectric nano films deposited on a newly developed nano graphene oxide membrane substrate.Its tunable equivalent thermal resistance is controlled by electrical currents to achieve energy-efficient temperature control for low-power electronics.A large cooling temperature difference of 44.5 K at 380 K is achieved with a power consumption of only 445μW,resulting in an ultrahigh temperature control capability over 100 K mW^(-1).Moreover,an ultra-fast cooling rate exceeding 2000 K s^(-1) and excellent reliability of up to 1 million cycles are observed.Our proposed on-chip temperature controller is expected to enable further miniaturization and multifunctional integration on a single chip for microelectronics.
文摘In this work, a rumor’s spreading and controlling in a directed Micro-blog user network being consisted with 580 000 nodes are simulated. By defining some authority nodes that release anti-rumor information as the prevention strategy, the effect of the nodes’ role in network on rumor’s suppression is studied. The findings show that rumor will be spread out fast and reach a stable level within limited steps. The suppression of rumor is more predominated by the intervening opportunity, the earlier the intervention strategy was implemented, the better the rumor’s controlling could be achieved. The controlling effect is less relevant with the role of the authority nodes in network.
基金supported by the National Science Foundation of China,the Basic and Applied Research of Nearinfrared Micro-imaging Technology in Biology(No20575076)
文摘The NIR micro-images of ibuprofen tablets were collected in this research.Compare correlation imaging and principal component analysis（PC A） with histogram were applied to acquire the spatial distribution of ibuprofen granule.The result indicated that a similar distribution trend can be acquired by both of the two methods mentioned above;the information of PC2 results from ibuprofen mainly since the correlation coefficient between PC2 loading vector and the NIR spectrum of ibuprofen is 0.9930.The result of PCA indicated that the information of PC2 results from ibuprofen mainly for both the low and the high content of ibuprofen in the tablets.The correlation coefficient between the data of the two PC2 loading vectors of the low and the high content of ibuprofen in the tablets is 0.9998,which indicates that the result of PCA is stable and reliable.
基金supported by the National Natural Science Foundation of China(52105296,51973165 and 62161160311)the Fundamental Research Funds for the Central Universities(2042022kf1220)+1 种基金Open Fund of Hubei Key Laboratory of Electronic Manufacturing and Packaging Integration(Wuhan University)(EMPI2023020)Large-scale Instrument And Equipment Sharing Foundation of Wuhan University.
文摘Excellent fluid sealing performance is crucial to ensuring the safety of important equipment,especially in aerospace field,such as space capsule and fuel chamber.The frequently opening and closing of the sealing devices is particularly important.Driven by this background,clams(Mactra chinensis)which can open and close their double shells with superior sealing performance,are studied in this work.Here,we show that the clam’s sealing ability is the result of its unique multilevel intermeshing microstructures,including hinge teeth and micro-blocks.These microstructures,which resemble gear teeth,engage with each other when the shell closes,forming a tight structure that prevents the infiltration of water from the outside.Furthermore,the presence of micron blocks prevents the penetration of finer liquids.The simulation results of the bionic end seal components show that the multilevel microstructure has a superior sealing effect.This research is expected to be applied to undersea vehicles that require frequent door opening and closing.
文摘Due to the rise of biological and MEMS technology in recent years, some micro flow system components have drawn attention and been developed by many investigators. The importance of micro-pumps manufactured is higher than the other part of micro flow system since it is the power source of the entire micro-flow system and responsible for driving working fluid in the microfluidic system. In actual operation, the instability and bad dynamic characteristics of the micro-pump will cause larger fluid flow mobility error, such as transport behavior and response procedures failure, etc., and even damage the microfluidic system. Therefore, to investigate the stability and dynamic characteristics of a micro pump is necessary. The Finite element analysis (FEA), ANSYS Workbench, is employed to analyze the dynamic characteristics of this micro pump, and experiment is also considered in this study.
文摘The influences of micro alloy and heat treatment procedure on the hardening of DJ108Ti alloy, which is based on the electrolytic Al Si(2 05%) Ti(0 25%) Fe(0 30%) multi component alloy, have been investigated. The results indicate that the micro alloy based on the multi component alloy makes α Al dendrites in DJ108Ti alloy refined; that the improved heat treatment procedure makes the eutectic Si phases granulated , the Fe phase refined, and the strengthening phases of Mg2Si and Al2Cu fully precipitated. The micro alloy and the heat treatment procedure harden DJ108Ti alloy and benefit the abrasion resistance of the alloy
文摘This research focused on integrating GIS into energy alternatives for climate change mitigation by creating a GIS-based hydrologic model that can be used to identify sites that have significant potential for micro hydropower development within the River Perkerra catchment area. Hydropower is a clean and renewable energy source that remains largely untapped in the country and its development can be used to mitigate anthropogenic climate change by reducing reliance on fossil or biomass derived fuels. This research established the extent of this resource and whether the available sites with significant micro hydropower potential within the study area were amply copious to warrant further development. Currently, such identification is done physically using means that are menial, costly and significantly time consuming. A 90-metre resolution Digital Terrain Model (DTM) data obtained from the Shuttle Radar Topography Mission and various GIS tools were used to create a hydrologic framework which was used to identify potential sites along River Perkerra that suited any desired head requirement for the purposes of locating micro hydropower plants. The derived model demonstrated that it was possible to identify sites at discrete geographic locations along any stream drainage network using GIS. In addition, the model also provides a decision support system that integrates a powerful graphical user interface, spatial database management system and a generalized river basin network flow model for the purposes of exploiting and developing micro hydropower. With sufficient data on catchment discharge and use of higher resolution DTM, the model can be further enhanced to accurately obtain the total microhydro potential of River Perkerra by aggregating the respective potentials of every steam segment.
文摘The ever increasing development of portable electronics has led to a higher demand for compact and reliable power sources. Significant resources are being presently dedicated to the study of micro machined gas turbines, because of their remarkable power density. The paper reports the procedures and the results of a series of tests conducted at the Department of Mechanical & Aerospace Engineering of University of Roma 1, to obtain the map of an ultra-micro gas turbine device, and the head losses and the combustion efficiency of the corresponding ultra-micro combustion chamber, fed by a mixture of butane and propane. This work is a part of a research aimed at the conception, design and prototyping of an ultra-micro thermo-electrical device for portable power generation. The novelty of the research consists in the fact that the thermal engine is a (ultra-micro) gas turbine set. In a subsequent stage, several different configurations have been assessed to select the most proper geometry and structural characteristics of the most relevant components (radial compressor, radial turbine, combustion chamber, electric motor and generator, bearings, regenerative heat exchanger).
