Wei He - Academia.edu (original) (raw)

Papers by Wei He

Scientific reports, 2016

Low-power and high-density electronic synapse is an important building block of brain-inspired sy... more Low-power and high-density electronic synapse is an important building block of brain-inspired systems. The recent advancement in memristor has provided an opportunity to advance electronic synapse design. However, a guideline on designing and manipulating the memristor's analog behaviors is still lacking. In this work, we reveal that compliance current (Icomp) of electroforming process played an important role in realizing a stable analog behavior, which is attributed to the generation of conical-type conductive filament. A proper Icomp could result in a large conductance window, good stability, and low voltage analog switching. We further reveal that different pulse conditions can lead to three analog behaviors, where the conductance changes in monotonic increase, plateau after initial jump, and impulse-like shape, respectively. These behaviors could benefit the design of electronic synapse with enriched learning capabilities. This work will provide a useful guideline for desi...

Scientific reports, 2016

Gap formation favors the growth of understory plants and affects the decomposition process of pla... more Gap formation favors the growth of understory plants and affects the decomposition process of plant debris inside and outside of gaps. Little information is available regarding how bioelement release from shrub litter is affected by gap formation during critical periods. The release of carbon (C), nitrogen (N), and phosphorus (P) in the foliar litter of Fargesia nitida and Salix paraplesia in response to gap locations was determined in an alpine forest of the eastern Qinghai-Tibet Plateau via a 2-year litter decomposition experiment. The daily release rates of C, N, and P increased from the closed canopy to the gap centers during the two winters, the two later growing seasons and the entire 2 years, whereas this trend was reversed during the two early growing seasons. The pairwise ratios among C, N, and P converged as the litter decomposition proceeded. Compared with the closed canopy, the gap centers displayed higher C:P and N:P ratio but a lower C:N ratio as the decomposition proc...

Environmental science and pollution research international, Jan 5, 2016

Surface sediment from large and eutrophic Lake Chaohu was investigated to determine the occurrenc... more Surface sediment from large and eutrophic Lake Chaohu was investigated to determine the occurrence, spatial distribution, sources, and risks of polychlorinated biphenyls (PCBs) and heavy metals in one of the five biggest freshwater lakes in China. Total concentration of PCBs (Σ34PCBs) in Lake Chaohu was 672 pg g(-1) dry weight (dw), with a range of 7 to 3999 pg g(-1) dw, which was lower than other water bodies worldwide. The majority of heavy metals were detected at all sampling locations, except for Sr, B, and In. Concentrations of Al, Fe, Ca, Mn, Sr, Co, Zn, Cd, Pb, and Hg were similar to that reported for other lakes globally. Concentrations of K, Mg, Na, Li, Ga, and Ag were greater than the average, whereas those of Cr, Ni, and Cu were lower. Cluster analysis (CA) and positive matrix factorization (PMF) yielded accordant results for the source apportionment of PCBs. The technical PCBs and microbial degradation accounted for 34.2 % and 65.8 % of total PCBs using PMF, and PMF reve...

Organic letters, Jan 4, 2016

Herein we report a Rh(I)-catalyzed two carbon insertion into C-C bonds of benzocyclobutenols by e... more Herein we report a Rh(I)-catalyzed two carbon insertion into C-C bonds of benzocyclobutenols by employing symmetrical and unsymmetrical allenes. This reaction provides rapid access to alkylidene tetralins bearing two adjacent stereogenic centers in good yields and diasteroselectivities.

Journal of agricultural and food chemistry, Jan 28, 2015

The identification and quantitation of the anthocyanins in 12 purple-fleshed sweet potato (PFSP) ... more The identification and quantitation of the anthocyanins in 12 purple-fleshed sweet potato (PFSP) cultivars ('Jihei 1', 'Xuzi 3', 'Xuzi 6', 'Zhezi 4', 'Ningzi 1', 'Ningzi…

Lecture Notes in Computer Science, 2010

Magnetic induction tomography (MIT) is a new medical functional imaging technique. This paper pro... more Magnetic induction tomography (MIT) is a new medical functional imaging technique. This paper proposes a multi-layer model of the biological tissue. And a new reconstruction method of magnetic induction tomography based on the improved genetic algorithm(GA) was introduced. The GA was improved from the following aspects: the generation of the initial population, selection, crossover and mutation operation. The simulation results indicate that the method can reflect local and large-area bleeding in the shallow of biological tissue, and construct a base for the future clinical brain disease monitoring.

Third International Conference on Smart Materials and Nanotechnology in Engineering, 2012

ABSTRACT Monitoring techniques based on fiber Bragg grating sensor have proved to exhibit meaning... more ABSTRACT Monitoring techniques based on fiber Bragg grating sensor have proved to exhibit meaningful benefits when compared with the current solutions of an electric nature in recent years. In this study, several fiber Bragg grating (FBG) strain sensors were embedded into a prestressed concrete dual-room box-girder when construction at a prefabrication workshop to monitor strain of concrete girder during prestressing tension. All FBG sensors are alive during monitoring, which shows the advantages of robust surviving capability and long-term on-line monitoring performance. From the monitoring results it is found that the variances in strain at the measurement sites are small and almost is linear with time in certain one tension process, and the strain at the measurement sites almost synchronously and linearly change with the increase of the prestress. It is also found that the changes in strain at the measurement sites during the final tension are larger than that during the early tension.

Ceramics International, 2015

ABSTRACT Li6.925+xLa3-xBaxZr1.925Sb0.075O12 (0≤x≤0.08) ceramics were prepared by conventional sol... more ABSTRACT Li6.925+xLa3-xBaxZr1.925Sb0.075O12 (0≤x≤0.08) ceramics were prepared by conventional solid-state reaction. The crystal structure, microstructure, ionic conductivity were characterized using XRD, SEM and Impedance analysis. XRD results showed that all compositions have a single cubic garnet-like structure. Li6.945La2.98Ba0.02Zr1.925Sb0.075O12 showed the highest conductivity and the lowest activation energy. The enhancement of its ionic conductivity could be explained by the enhanced densification and occupation on Li2 site.

Journal of Materials Chemistry A, 2014

ABSTRACT Improvements in the electrical conductivity and lithium (Li) mobility for Li ion batteri... more ABSTRACT Improvements in the electrical conductivity and lithium (Li) mobility for Li ion batteries are of particular importance for their high-power applications. Mapping of electron energy loss spectroscopy shows that the electrochemical reaction front region is under electron-rich conditions during lithiation. In this paper, the electron-rich effect on the diffusion behaviors of Li in pristine and phosphorus-doped group IVA elements, e.g., silicon, germanium and tin, were investigated using the first principles density functional theory (DFT) calculations in combination with a climbing-image nudged elastic band and ab initio DFT molecular dynamics. Phosphorus doping was found to be a non-critical factor for enhanced Li diffusion into Si. Instead, the results showed that the diffusion barriers and diffusivity of Li are mainly affected by the electron-rich effect, i.e. the energy barriers decrease and diffusivity increases in an electron-rich environment. The decrease in diffusion barriers was attributed to the relaxation of Si–Si bonds with extra electrons, which can also apply to the case of Ge but not for metallic Sn. These new findings provide a theoretical and experimental basis for the design and fabrication of next generation batteries with a high power density.

Solar Energy Materials and Solar Cells, 2015

Lecture Notes in Computer Science, 2013

ABSTRACT A unified platform to extract all kinds of vocabulary should be required for vocabulary ... more ABSTRACT A unified platform to extract all kinds of vocabulary should be required for vocabulary monitoring. We argue just like other physical movements all words are doing the temporal-spatial movement. The classification of vocabulary is actually based on the types of movement. To model the temporal-spatial movement will lead to the extraction of all kinds of words. Therefore this paper proposes the temporal-spatial model of vocabulary movement with three quantities that is the state function, the state change function and the speed function. Furthermore the two new metrics (the normalized usage and the usage ratio) are proposed to calculate the model quantities. The model has been applied to extract the catchwords, new words, terminologies, commonly used words, and emergency terms. The results show that the temporal-spatial model has good robustness, which can eliminate the influence of the different corpus scale and give a package solution for vocabulary monitoring.

2009 Sixth International Conference on Information Technology: New Generations, 2009

To separate fine particles from waste water, a novel hydrocyclone was designed which features two... more To separate fine particles from waste water, a novel hydrocyclone was designed which features two cone sections. It is expected that flowrate can be increased at high separation efficiency without additional demand of pressure drop. This paper presents experimental investigations on its pressure drop characteristics. In this paper, influences of flowrate, split ratio, protrudent length of vertex finder, inlet area,

Cancer investigation, Jan 7, 2015

Erlotinib is a standard second-line therapy for patients with advanced non-small-cell lung cancer... more Erlotinib is a standard second-line therapy for patients with advanced non-small-cell lung cancer (NSCLC). However, its efficacy for those patients with epidermal growth factor receptor (EGFR) wild-type (WT) tumors is undecided. In this randomized phase II study, NSCLC patients with EGFR-WT tumors, who had been treated with platinum-based chemotherapy but still developed disease progression, were assigned to receive second-line treatment of erlotinib plus nab-paclitaxel or erlotinib alone. We found PFS and OS were significantly improved by erlotinib plus nab-paclitaxel. The adverse events were also well tolerable.

Proceedings 2011 International Conference on Human Health and Biomedical Engineering, 2011

In this study, the antioxidant responses induced by menadione in zebrafish (Danio rerio) were ana... more In this study, the antioxidant responses induced by menadione in zebrafish (Danio rerio) were analyzed. Changes in activities of superoxide dismutase (SOD), and catalase (CAT) in the liver, gill, muscle and kidney of fish were determined. The results showed that there were significant changes in SOD and CAT activities along with the different time and concentrations to different organs and

ChemInform, 2008

The recyclable ligand (I) is applied to osmium-catalyzed asymmetric aminohydroxylation reactions ... more The recyclable ligand (I) is applied to osmium-catalyzed asymmetric aminohydroxylation reactions of olefins. The addition of a small amount of polyethylene glycol 400 keeps the osmium (together with the ligand) in the aqueous phase during work-up. 50 percent of osmium could be recycled. -(SUN, X. L.; JIN, Y.; HE, W.; NAN, P.

Applied Mechanics and Materials, 2015

Computer-Aided Architectural Design Futures (CAADFutures) 2007, 2007

Functionally gradient materials (FGMs) are a new class of materials in which the composition and/... more Functionally gradient materials (FGMs) are a new class of materials in which the composition and/or the microstructure varies in one specific direction . The main advantage of FGMs is the gradual change of properties resulting from the gradient in the structure and reinforcement phases, which can avoid problems due to the mismatches in thermal expansion . A number of FGM manufacturing methods have been proposed, such as chemical vapor deposition , the plasma spray technique and various powder metallurgy techniques . The centrifugal method was introduced recently and has drawn a lot of attention due to its unique merits . In this method, the composition gradient is formed as a result of the difference in the centrifugal force which is generated by the difference in density between the molten metallic phase and the particles. At present, several FGMs have been prepared using a centrifugal method and most of them have an Al-matrix. However, most of the particulate reinforcements have higher densities than the Al matrix. Thus, few Al-matrix FGMs have a concentration of the reinforcement in the inner layer of the tube formed by the centrifugal method . It is however a more common requirement for cylindrical components to have special properties in inner layer, such as a high wear-resistance. In this paper, ZA27 was selected as the master alloy, as it is widely used as a cost and energy efficient substitute material for several ferrous and non-ferrous alloys in many engineering applications . Elemental Si is often added to the alloy to form hard, primary Si particles and to further improve the wear properties . The presence of silicon particles, however, impairs the ductility of the alloys while improving wear properties . In this study, most of the hard and crack-sensitive primary silicon particles were segregated to the inner layer by centrifugally casting. Thus, an FGM tube with high wear-resistance on the inside surface was fabricated which retained relatively good ductility in the matrix.

Scientific reports, 2016

Low-power and high-density electronic synapse is an important building block of brain-inspired sy... more Low-power and high-density electronic synapse is an important building block of brain-inspired systems. The recent advancement in memristor has provided an opportunity to advance electronic synapse design. However, a guideline on designing and manipulating the memristor's analog behaviors is still lacking. In this work, we reveal that compliance current (Icomp) of electroforming process played an important role in realizing a stable analog behavior, which is attributed to the generation of conical-type conductive filament. A proper Icomp could result in a large conductance window, good stability, and low voltage analog switching. We further reveal that different pulse conditions can lead to three analog behaviors, where the conductance changes in monotonic increase, plateau after initial jump, and impulse-like shape, respectively. These behaviors could benefit the design of electronic synapse with enriched learning capabilities. This work will provide a useful guideline for desi...

Scientific reports, 2016

Gap formation favors the growth of understory plants and affects the decomposition process of pla... more Gap formation favors the growth of understory plants and affects the decomposition process of plant debris inside and outside of gaps. Little information is available regarding how bioelement release from shrub litter is affected by gap formation during critical periods. The release of carbon (C), nitrogen (N), and phosphorus (P) in the foliar litter of Fargesia nitida and Salix paraplesia in response to gap locations was determined in an alpine forest of the eastern Qinghai-Tibet Plateau via a 2-year litter decomposition experiment. The daily release rates of C, N, and P increased from the closed canopy to the gap centers during the two winters, the two later growing seasons and the entire 2 years, whereas this trend was reversed during the two early growing seasons. The pairwise ratios among C, N, and P converged as the litter decomposition proceeded. Compared with the closed canopy, the gap centers displayed higher C:P and N:P ratio but a lower C:N ratio as the decomposition proc...

Environmental science and pollution research international, Jan 5, 2016

Surface sediment from large and eutrophic Lake Chaohu was investigated to determine the occurrenc... more Surface sediment from large and eutrophic Lake Chaohu was investigated to determine the occurrence, spatial distribution, sources, and risks of polychlorinated biphenyls (PCBs) and heavy metals in one of the five biggest freshwater lakes in China. Total concentration of PCBs (Σ34PCBs) in Lake Chaohu was 672 pg g(-1) dry weight (dw), with a range of 7 to 3999 pg g(-1) dw, which was lower than other water bodies worldwide. The majority of heavy metals were detected at all sampling locations, except for Sr, B, and In. Concentrations of Al, Fe, Ca, Mn, Sr, Co, Zn, Cd, Pb, and Hg were similar to that reported for other lakes globally. Concentrations of K, Mg, Na, Li, Ga, and Ag were greater than the average, whereas those of Cr, Ni, and Cu were lower. Cluster analysis (CA) and positive matrix factorization (PMF) yielded accordant results for the source apportionment of PCBs. The technical PCBs and microbial degradation accounted for 34.2 % and 65.8 % of total PCBs using PMF, and PMF reve...

Organic letters, Jan 4, 2016

Herein we report a Rh(I)-catalyzed two carbon insertion into C-C bonds of benzocyclobutenols by e... more Herein we report a Rh(I)-catalyzed two carbon insertion into C-C bonds of benzocyclobutenols by employing symmetrical and unsymmetrical allenes. This reaction provides rapid access to alkylidene tetralins bearing two adjacent stereogenic centers in good yields and diasteroselectivities.

Journal of agricultural and food chemistry, Jan 28, 2015

The identification and quantitation of the anthocyanins in 12 purple-fleshed sweet potato (PFSP) ... more The identification and quantitation of the anthocyanins in 12 purple-fleshed sweet potato (PFSP) cultivars ('Jihei 1', 'Xuzi 3', 'Xuzi 6', 'Zhezi 4', 'Ningzi 1', 'Ningzi…

Lecture Notes in Computer Science, 2010

Magnetic induction tomography (MIT) is a new medical functional imaging technique. This paper pro... more Magnetic induction tomography (MIT) is a new medical functional imaging technique. This paper proposes a multi-layer model of the biological tissue. And a new reconstruction method of magnetic induction tomography based on the improved genetic algorithm(GA) was introduced. The GA was improved from the following aspects: the generation of the initial population, selection, crossover and mutation operation. The simulation results indicate that the method can reflect local and large-area bleeding in the shallow of biological tissue, and construct a base for the future clinical brain disease monitoring.

Third International Conference on Smart Materials and Nanotechnology in Engineering, 2012

ABSTRACT Monitoring techniques based on fiber Bragg grating sensor have proved to exhibit meaning... more ABSTRACT Monitoring techniques based on fiber Bragg grating sensor have proved to exhibit meaningful benefits when compared with the current solutions of an electric nature in recent years. In this study, several fiber Bragg grating (FBG) strain sensors were embedded into a prestressed concrete dual-room box-girder when construction at a prefabrication workshop to monitor strain of concrete girder during prestressing tension. All FBG sensors are alive during monitoring, which shows the advantages of robust surviving capability and long-term on-line monitoring performance. From the monitoring results it is found that the variances in strain at the measurement sites are small and almost is linear with time in certain one tension process, and the strain at the measurement sites almost synchronously and linearly change with the increase of the prestress. It is also found that the changes in strain at the measurement sites during the final tension are larger than that during the early tension.

Ceramics International, 2015

ABSTRACT Li6.925+xLa3-xBaxZr1.925Sb0.075O12 (0≤x≤0.08) ceramics were prepared by conventional sol... more ABSTRACT Li6.925+xLa3-xBaxZr1.925Sb0.075O12 (0≤x≤0.08) ceramics were prepared by conventional solid-state reaction. The crystal structure, microstructure, ionic conductivity were characterized using XRD, SEM and Impedance analysis. XRD results showed that all compositions have a single cubic garnet-like structure. Li6.945La2.98Ba0.02Zr1.925Sb0.075O12 showed the highest conductivity and the lowest activation energy. The enhancement of its ionic conductivity could be explained by the enhanced densification and occupation on Li2 site.

Journal of Materials Chemistry A, 2014

ABSTRACT Improvements in the electrical conductivity and lithium (Li) mobility for Li ion batteri... more ABSTRACT Improvements in the electrical conductivity and lithium (Li) mobility for Li ion batteries are of particular importance for their high-power applications. Mapping of electron energy loss spectroscopy shows that the electrochemical reaction front region is under electron-rich conditions during lithiation. In this paper, the electron-rich effect on the diffusion behaviors of Li in pristine and phosphorus-doped group IVA elements, e.g., silicon, germanium and tin, were investigated using the first principles density functional theory (DFT) calculations in combination with a climbing-image nudged elastic band and ab initio DFT molecular dynamics. Phosphorus doping was found to be a non-critical factor for enhanced Li diffusion into Si. Instead, the results showed that the diffusion barriers and diffusivity of Li are mainly affected by the electron-rich effect, i.e. the energy barriers decrease and diffusivity increases in an electron-rich environment. The decrease in diffusion barriers was attributed to the relaxation of Si–Si bonds with extra electrons, which can also apply to the case of Ge but not for metallic Sn. These new findings provide a theoretical and experimental basis for the design and fabrication of next generation batteries with a high power density.

Solar Energy Materials and Solar Cells, 2015

Lecture Notes in Computer Science, 2013

ABSTRACT A unified platform to extract all kinds of vocabulary should be required for vocabulary ... more ABSTRACT A unified platform to extract all kinds of vocabulary should be required for vocabulary monitoring. We argue just like other physical movements all words are doing the temporal-spatial movement. The classification of vocabulary is actually based on the types of movement. To model the temporal-spatial movement will lead to the extraction of all kinds of words. Therefore this paper proposes the temporal-spatial model of vocabulary movement with three quantities that is the state function, the state change function and the speed function. Furthermore the two new metrics (the normalized usage and the usage ratio) are proposed to calculate the model quantities. The model has been applied to extract the catchwords, new words, terminologies, commonly used words, and emergency terms. The results show that the temporal-spatial model has good robustness, which can eliminate the influence of the different corpus scale and give a package solution for vocabulary monitoring.

2009 Sixth International Conference on Information Technology: New Generations, 2009

To separate fine particles from waste water, a novel hydrocyclone was designed which features two... more To separate fine particles from waste water, a novel hydrocyclone was designed which features two cone sections. It is expected that flowrate can be increased at high separation efficiency without additional demand of pressure drop. This paper presents experimental investigations on its pressure drop characteristics. In this paper, influences of flowrate, split ratio, protrudent length of vertex finder, inlet area,

Cancer investigation, Jan 7, 2015

Erlotinib is a standard second-line therapy for patients with advanced non-small-cell lung cancer... more Erlotinib is a standard second-line therapy for patients with advanced non-small-cell lung cancer (NSCLC). However, its efficacy for those patients with epidermal growth factor receptor (EGFR) wild-type (WT) tumors is undecided. In this randomized phase II study, NSCLC patients with EGFR-WT tumors, who had been treated with platinum-based chemotherapy but still developed disease progression, were assigned to receive second-line treatment of erlotinib plus nab-paclitaxel or erlotinib alone. We found PFS and OS were significantly improved by erlotinib plus nab-paclitaxel. The adverse events were also well tolerable.

Proceedings 2011 International Conference on Human Health and Biomedical Engineering, 2011

In this study, the antioxidant responses induced by menadione in zebrafish (Danio rerio) were ana... more In this study, the antioxidant responses induced by menadione in zebrafish (Danio rerio) were analyzed. Changes in activities of superoxide dismutase (SOD), and catalase (CAT) in the liver, gill, muscle and kidney of fish were determined. The results showed that there were significant changes in SOD and CAT activities along with the different time and concentrations to different organs and

ChemInform, 2008

The recyclable ligand (I) is applied to osmium-catalyzed asymmetric aminohydroxylation reactions ... more The recyclable ligand (I) is applied to osmium-catalyzed asymmetric aminohydroxylation reactions of olefins. The addition of a small amount of polyethylene glycol 400 keeps the osmium (together with the ligand) in the aqueous phase during work-up. 50 percent of osmium could be recycled. -(SUN, X. L.; JIN, Y.; HE, W.; NAN, P.

Applied Mechanics and Materials, 2015

Computer-Aided Architectural Design Futures (CAADFutures) 2007, 2007

Functionally gradient materials (FGMs) are a new class of materials in which the composition and/... more Functionally gradient materials (FGMs) are a new class of materials in which the composition and/or the microstructure varies in one specific direction . The main advantage of FGMs is the gradual change of properties resulting from the gradient in the structure and reinforcement phases, which can avoid problems due to the mismatches in thermal expansion . A number of FGM manufacturing methods have been proposed, such as chemical vapor deposition , the plasma spray technique and various powder metallurgy techniques . The centrifugal method was introduced recently and has drawn a lot of attention due to its unique merits . In this method, the composition gradient is formed as a result of the difference in the centrifugal force which is generated by the difference in density between the molten metallic phase and the particles. At present, several FGMs have been prepared using a centrifugal method and most of them have an Al-matrix. However, most of the particulate reinforcements have higher densities than the Al matrix. Thus, few Al-matrix FGMs have a concentration of the reinforcement in the inner layer of the tube formed by the centrifugal method . It is however a more common requirement for cylindrical components to have special properties in inner layer, such as a high wear-resistance. In this paper, ZA27 was selected as the master alloy, as it is widely used as a cost and energy efficient substitute material for several ferrous and non-ferrous alloys in many engineering applications . Elemental Si is often added to the alloy to form hard, primary Si particles and to further improve the wear properties . The presence of silicon particles, however, impairs the ductility of the alloys while improving wear properties . In this study, most of the hard and crack-sensitive primary silicon particles were segregated to the inner layer by centrifugally casting. Thus, an FGM tube with high wear-resistance on the inside surface was fabricated which retained relatively good ductility in the matrix.