We study a radio frequency(RF) wireless energy transfer(WET) enabled multiple input multiple output(MIMO) system. A time slotted transmission pattern is considered. Each slot can be divided into two phases, downlink(D...We study a radio frequency(RF) wireless energy transfer(WET) enabled multiple input multiple output(MIMO) system. A time slotted transmission pattern is considered. Each slot can be divided into two phases, downlink(DL) WET and uplink(UL) wireless information transmission(WIT). Since energy conversion efficiency of the energy harvesting circuits are non.linear, the conventional linear model leads to a mismatch for resource allocation. In this paper, the power allocation algorithm considering the practical non.linear energy harvesting circuits is studied. The optimization problem is formulated to maximize the energy efficiency of system with multiple constraints, i.e., the transmission power, the received power and the minimum harvested energy, which is a non.convex problem. We transform the objective function from fractional form into an equivalent objective function in subtractive form and provide an iterative power allocation algorithm to achieve the optimal solution. Numerical results show that our proposed algorithm with the non.linear RF energy conversion models can achieve much better performance than the algorithm with the conventional linear model.展开更多
A process to convert models made by rapid prototypi ng techniques like SL (stereolitography) and LOM (laminated object manufacturing) or by conventional techniques (silicones, resins, wax, etc.) into metallic mould s ...A process to convert models made by rapid prototypi ng techniques like SL (stereolitography) and LOM (laminated object manufacturing) or by conventional techniques (silicones, resins, wax, etc.) into metallic mould s or tools has been developed. The main purpose of this technique is to rapidly obtain the first prototypes of parts, for plastics injection, forging or any oth er manufacturing process using the tools produced by casting a metal into a cera mic mould. Briefly, it can be said that the ceramic moulds are produced by mixing in variab le proportions, depending on the type of ceramics employed, strength and roughne ss desired, a ceramic mixture composed by alumina and/or zirconium silicates bon ded with silica coming from a liquid binder, based on ethyl silicate. A catalyst is added to the slurry in order to produce a sol-gel reaction. The liquid slur ry is poured into the box containing the mould to be reproduced. After a short p eriod of time, controlled by the amount of gelling agent, the ceramic mixture ac quires a rubber consistency. The pattern is removed from the ceramic mould, whic h is fired to stop the gelation reaction. After this stabilization the ceramic m ould is sintered at high temperatures in order to generate an inert mould wi th the desired strength in which almost all metallic alloys can be cast. The effect of ceramic materials (shape, granulometric distribution, chemical com position, etc.), processing parameters (proportion binder/ceramic/catalyst, sint ering conditions, etc.) and casting conditions (mould pre-heating temperature a nd pouring temperature) were studied in order to obtain metallic moulds or tools with tailored properties (high dimensional accuracy, low roughness and high mec hanical strength).展开更多
With the increase in the coverage area of magnetotelluric data,three-dimensional magnetotelluric modeling in spherical coordinates and its differences with respect to traditional Cartesian modeling have gradually attr...With the increase in the coverage area of magnetotelluric data,three-dimensional magnetotelluric modeling in spherical coordinates and its differences with respect to traditional Cartesian modeling have gradually attracted attention.To fully understand the influence of the Earth’s curvature and map projection deformations on Cartesian modeling,qualitative and quantitative analyses based on realistic three-dimensional models need to be examined.Combined with five representative map projections,a type of model conversion method that transforms the original spherical electrical conductivity model to Cartesian coordinates is described in this study.The apparent resistivity differences between the spherical western United States electrical conductivity model and the corresponding five Cartesian models are then compared.The results show that the cylindrical equal distance map projection has the smallest error.A meridian convergence correction resulting from the deformation of the map projection is introduced to rotate the Cartesian impedance tensor from grid north to geographic north,which reduces differences from the spherical results.On the basis of the magnetotelluric field data,the applicability of the Cartesian coordinate system to western and contiguous United States models is quantitatively evaluated.Precise interpretations of the contiguous United States model were found to require spherical coordinates.展开更多
A new methodology of voice conversion in cepstrum eigenspace based on structured Gaussian mixture model is proposed for non-parallel corpora without joint training. For each speaker, the cepstrum features of speech ar...A new methodology of voice conversion in cepstrum eigenspace based on structured Gaussian mixture model is proposed for non-parallel corpora without joint training. For each speaker, the cepstrum features of speech are extracted, and mapped to the eigenspace which is formed by eigenvectors of its scatter matrix, thereby the Structured Gaussian Mixture Model in the EigenSpace （SGMM-ES） is trained. The source and target speaker＇s SGMM-ES are matched based on Acoustic Universal Structure （AUS） principle to achieve spectrum transform function. Experimental results show the speaker identification rate of conversion speech achieves 95.25%, and the value of average cepstrum distortion is 1.25 which is 0.8% and 7.3% higher than the performance of SGMM method respectively. ABX and MOS evaluations indicate the conversion performance is quite close to the traditional method under the parallel corpora condition. The results show the eigenspace based structured Gaussian mixture model for voice conversion under the non-parallel corpora is effective.展开更多
Directing to the weakness of the present fixed values mapping methods （method_F）, a vocal tract system conversion method based on the universal background model （UBM） is proposed for improving the performance of t...Directing to the weakness of the present fixed values mapping methods （method_F）, a vocal tract system conversion method based on the universal background model （UBM） is proposed for improving the performance of the speech conversion system from Chinese whis- pered speech to normal speech. For the numerous components of UBM, the errors produced by the acoustical probability density statistical model can＇t be ignored. Thus an effective Gaus- sian mixture components chosen method based on the posterior probability summation of the minimum spectral distortion is developed to optimizing the system performance. The proposed method （method_U） is analyzed and compared using the performance index （PI） based on Itakura-Saito spectral distortion measure. It is shown experimentally that the performance of method_U is more stability for different speakers and different phonemes than that of method_F. The average PI of method_U is better than method_F. It is shown that by selecting effective Gaussian mixture components, the PI of method_U can be further improved 5.11%. Subjective auditory tests also show that the proposed method can improve the definition and intelligibility of conversion speech.展开更多
Addressing climate change has become a common issue around the world in the 21st century and equally an important mission in Chinese forestry.Understanding the development of monitoring and assessment of forest biomas...Addressing climate change has become a common issue around the world in the 21st century and equally an important mission in Chinese forestry.Understanding the development of monitoring and assessment of forest biomass and carbon storage in China is important for promoting the evaluation of forest carbon sequestration capacity of China.The author conducts a systematic analysis of domestic publications addressing＂monitoring and assessment of forest biomass and carbon storage＂in order to understand the development trends,describes the brief history through three stages,and gives the situation of new development.Towards the end of the 20th century,a large number of papers on biomass and productivity of the major forest types in China had been published,covering the exploration and efforts of more than 20 years,while investigations into assessment of forest carbon storage had barely begun.Based on the data of the 7th and 8th National Forest Inventories,forest biomass and carbon storage of the entire country were assessed using individual tree biomass models and carbon conversion factors of major tree species,both previously published and newly developed.Accompanying the implementation of the 8th National Forest Inventory,a program of individual tree biomass modeling for major tree species in China was carried out simultaneously.By means of thematic research on classification of modeling populations,as well as procedures for collecting samples and methodology for biomass modeling,two technical regulations on sample collection and model construction were published as ministerial standards for application.Requests for approval of individual tree biomass models and carbon accounting parameters of major tree species have been issued for approval as ministerial standards.With the improvement of biomass models and carbon accounting parameters,thematic assessment of forest biomass and carbon storage will be gradually changed into a general monitoring of forest biomass and carbon storage,in order to realize their dynamic monitoring in national forest inventories.Strengthening the analysis and assessment of spatial distribution patterns of forest biomass and carbon storage through application of remote sensing techniques and geostatistical approaches will also be one of the major directions of development in the near future.展开更多
Large-scale pre-training has shown remarkable performance in building open-domain dialogue systems.However,previous works mainly focus on showing and evaluating the conversational performance of the released dialogue ...Large-scale pre-training has shown remarkable performance in building open-domain dialogue systems.However,previous works mainly focus on showing and evaluating the conversational performance of the released dialogue model,ignoring the discussion of some key factors towards a powerful human-like chatbot,especially in Chinese scenarios.In this paper,we conduct extensive experiments to investigate these under-explored factors,including data quality control,model architecture designs,training approaches,and decoding strategies.We propose EVA2.0,a large-scale pre-trained open-domain Chinese dialogue model with 2.8 billion parameters,and will make our models and codes publicly available.Automatic and human evaluations show that EVA2.0 significantly outperforms other open-source counterparts.We also discuss the limitations of this work by presenting some failure cases and pose some future research directions on large-scale Chinese open-domain dialogue systems.展开更多
The recently emerging laser-induced graphene(LIG)technology,with one-step processing and designable features,has been widely used in the fabrication of wearable/portable electronics.Herein,by taking inspiration from k...The recently emerging laser-induced graphene(LIG)technology,with one-step processing and designable features,has been widely used in the fabrication of wearable/portable electronics.Herein,by taking inspiration from kirigami,we designed a stretchable supercapacitor(SC)step by step through controlling laser induction and cutting process on the polyimide(PI)film,with the use of one single CO_(2) laser source.Firstly,the carbonized basic geometric units of lines were produced on PI films to investigate the processing-structure relationships.Then,the complex photothermal conversion and heat transfer progress involved in the carbonized process were simulated by a photothermal model.Both experimental and theoretical results suggested that the laser power,scan rate and focus condition have great influence on the size,shape and morphology of the carbonized lines.Finally,we optimized the parameters of laser induction and cutting process to fabricate the kirigami-inspired SCs with reliable electrochemical properties and editable mechanical flexibility,showing great potential in the field of flexible electronics.展开更多
Pluripotency-associated factors and their rivals, lineage specifiers, have long been consid- ered the determining factors for the identity of pluripotent and differentiated cells, respectively. Therefore, factors that...Pluripotency-associated factors and their rivals, lineage specifiers, have long been consid- ered the determining factors for the identity of pluripotent and differentiated cells, respectively. Therefore, factors that are employed for cellular reprogramming in order to induce pluripotency have been identified mainly from embryonic stem cell （ESC）-enriched and pluripotency-associated factors. Recently, lineage specifiers have been identified to play important roles in orchestrating the process of restoring pluripotency. In this review, we summarize the latest discoveries regarding cell fate conversion using pluripotency-associated factors and lineage specifiers. We highlight the value of the ＂seesaw＂ model in defining cellular identity, opening up a novel scenario to consider pluri- potency and lineage specification.展开更多
基金supported in part by National Natural Science Foundation of China (61372070)Natural Science Basic Research Plan in Shaanxi Province of China (2015JM6324)+2 种基金Ningbo Natural Science Foundation (2015A610117)Hong Kong, Macao and Taiwan Science & Technology Cooperation Program of China (2015DFT10160)the 111 Project (B08038)
文摘We study a radio frequency(RF) wireless energy transfer(WET) enabled multiple input multiple output(MIMO) system. A time slotted transmission pattern is considered. Each slot can be divided into two phases, downlink(DL) WET and uplink(UL) wireless information transmission(WIT). Since energy conversion efficiency of the energy harvesting circuits are non.linear, the conventional linear model leads to a mismatch for resource allocation. In this paper, the power allocation algorithm considering the practical non.linear energy harvesting circuits is studied. The optimization problem is formulated to maximize the energy efficiency of system with multiple constraints, i.e., the transmission power, the received power and the minimum harvested energy, which is a non.convex problem. We transform the objective function from fractional form into an equivalent objective function in subtractive form and provide an iterative power allocation algorithm to achieve the optimal solution. Numerical results show that our proposed algorithm with the non.linear RF energy conversion models can achieve much better performance than the algorithm with the conventional linear model.
文摘A process to convert models made by rapid prototypi ng techniques like SL (stereolitography) and LOM (laminated object manufacturing) or by conventional techniques (silicones, resins, wax, etc.) into metallic mould s or tools has been developed. The main purpose of this technique is to rapidly obtain the first prototypes of parts, for plastics injection, forging or any oth er manufacturing process using the tools produced by casting a metal into a cera mic mould. Briefly, it can be said that the ceramic moulds are produced by mixing in variab le proportions, depending on the type of ceramics employed, strength and roughne ss desired, a ceramic mixture composed by alumina and/or zirconium silicates bon ded with silica coming from a liquid binder, based on ethyl silicate. A catalyst is added to the slurry in order to produce a sol-gel reaction. The liquid slur ry is poured into the box containing the mould to be reproduced. After a short p eriod of time, controlled by the amount of gelling agent, the ceramic mixture ac quires a rubber consistency. The pattern is removed from the ceramic mould, whic h is fired to stop the gelation reaction. After this stabilization the ceramic m ould is sintered at high temperatures in order to generate an inert mould wi th the desired strength in which almost all metallic alloys can be cast. The effect of ceramic materials (shape, granulometric distribution, chemical com position, etc.), processing parameters (proportion binder/ceramic/catalyst, sint ering conditions, etc.) and casting conditions (mould pre-heating temperature a nd pouring temperature) were studied in order to obtain metallic moulds or tools with tailored properties (high dimensional accuracy, low roughness and high mec hanical strength).
基金the National Natural Science Foundation of China(Nos.42220104002,42104073,and 41630317).
文摘With the increase in the coverage area of magnetotelluric data,three-dimensional magnetotelluric modeling in spherical coordinates and its differences with respect to traditional Cartesian modeling have gradually attracted attention.To fully understand the influence of the Earth’s curvature and map projection deformations on Cartesian modeling,qualitative and quantitative analyses based on realistic three-dimensional models need to be examined.Combined with five representative map projections,a type of model conversion method that transforms the original spherical electrical conductivity model to Cartesian coordinates is described in this study.The apparent resistivity differences between the spherical western United States electrical conductivity model and the corresponding five Cartesian models are then compared.The results show that the cylindrical equal distance map projection has the smallest error.A meridian convergence correction resulting from the deformation of the map projection is introduced to rotate the Cartesian impedance tensor from grid north to geographic north,which reduces differences from the spherical results.On the basis of the magnetotelluric field data,the applicability of the Cartesian coordinate system to western and contiguous United States models is quantitatively evaluated.Precise interpretations of the contiguous United States model were found to require spherical coordinates.
基金supported by the Natural Science Foundation of China(61271360)the Application Fundamental Research Project of Suzhou(SYG201230)
文摘A new methodology of voice conversion in cepstrum eigenspace based on structured Gaussian mixture model is proposed for non-parallel corpora without joint training. For each speaker, the cepstrum features of speech are extracted, and mapped to the eigenspace which is formed by eigenvectors of its scatter matrix, thereby the Structured Gaussian Mixture Model in the EigenSpace （SGMM-ES） is trained. The source and target speaker＇s SGMM-ES are matched based on Acoustic Universal Structure （AUS） principle to achieve spectrum transform function. Experimental results show the speaker identification rate of conversion speech achieves 95.25%, and the value of average cepstrum distortion is 1.25 which is 0.8% and 7.3% higher than the performance of SGMM method respectively. ABX and MOS evaluations indicate the conversion performance is quite close to the traditional method under the parallel corpora condition. The results show the eigenspace based structured Gaussian mixture model for voice conversion under the non-parallel corpora is effective.
基金supported by the National Natural Science Foundation of China(61071215)the Science and Technology Foundation of Suzhou(SYG201033)the Pre-research Foundation of Soochow University(Q311901111,14317399)
文摘Directing to the weakness of the present fixed values mapping methods （method_F）, a vocal tract system conversion method based on the universal background model （UBM） is proposed for improving the performance of the speech conversion system from Chinese whis- pered speech to normal speech. For the numerous components of UBM, the errors produced by the acoustical probability density statistical model can＇t be ignored. Thus an effective Gaus- sian mixture components chosen method based on the posterior probability summation of the minimum spectral distortion is developed to optimizing the system performance. The proposed method （method_U） is analyzed and compared using the performance index （PI） based on Itakura-Saito spectral distortion measure. It is shown experimentally that the performance of method_U is more stability for different speakers and different phonemes than that of method_F. The average PI of method_U is better than method_F. It is shown that by selecting effective Gaussian mixture components, the PI of method_U can be further improved 5.11%. Subjective auditory tests also show that the proposed method can improve the definition and intelligibility of conversion speech.
基金funded by the State Forestry Administration of China
文摘Addressing climate change has become a common issue around the world in the 21st century and equally an important mission in Chinese forestry.Understanding the development of monitoring and assessment of forest biomass and carbon storage in China is important for promoting the evaluation of forest carbon sequestration capacity of China.The author conducts a systematic analysis of domestic publications addressing＂monitoring and assessment of forest biomass and carbon storage＂in order to understand the development trends,describes the brief history through three stages,and gives the situation of new development.Towards the end of the 20th century,a large number of papers on biomass and productivity of the major forest types in China had been published,covering the exploration and efforts of more than 20 years,while investigations into assessment of forest carbon storage had barely begun.Based on the data of the 7th and 8th National Forest Inventories,forest biomass and carbon storage of the entire country were assessed using individual tree biomass models and carbon conversion factors of major tree species,both previously published and newly developed.Accompanying the implementation of the 8th National Forest Inventory,a program of individual tree biomass modeling for major tree species in China was carried out simultaneously.By means of thematic research on classification of modeling populations,as well as procedures for collecting samples and methodology for biomass modeling,two technical regulations on sample collection and model construction were published as ministerial standards for application.Requests for approval of individual tree biomass models and carbon accounting parameters of major tree species have been issued for approval as ministerial standards.With the improvement of biomass models and carbon accounting parameters,thematic assessment of forest biomass and carbon storage will be gradually changed into a general monitoring of forest biomass and carbon storage,in order to realize their dynamic monitoring in national forest inventories.Strengthening the analysis and assessment of spatial distribution patterns of forest biomass and carbon storage through application of remote sensing techniques and geostatistical approaches will also be one of the major directions of development in the near future.
基金supported by the 2030 National Key AI Program of China(No.2021ZD0113304)the National Science Foundation for Distinguished Young Scholars(No.62125604)+2 种基金the NSFC projects(Key project with No.61936010 and regular project with No.61876096)the Guoqiang Institute of Tsinghua University,China(Nos.2019GQG1 and 2020GQG0005)Tsinghua-Toyota Joint Research Fund.
文摘Large-scale pre-training has shown remarkable performance in building open-domain dialogue systems.However,previous works mainly focus on showing and evaluating the conversational performance of the released dialogue model,ignoring the discussion of some key factors towards a powerful human-like chatbot,especially in Chinese scenarios.In this paper,we conduct extensive experiments to investigate these under-explored factors,including data quality control,model architecture designs,training approaches,and decoding strategies.We propose EVA2.0,a large-scale pre-trained open-domain Chinese dialogue model with 2.8 billion parameters,and will make our models and codes publicly available.Automatic and human evaluations show that EVA2.0 significantly outperforms other open-source counterparts.We also discuss the limitations of this work by presenting some failure cases and pose some future research directions on large-scale Chinese open-domain dialogue systems.
基金the National Natural Science Foundation of China(Grant No.51775197)the Science and Technology Planning Project of Guangdong Province(Grant No.2018A050506007)the Guangzhou Science and Technology Program Project(Grant No.201704020090)。
文摘The recently emerging laser-induced graphene(LIG)technology,with one-step processing and designable features,has been widely used in the fabrication of wearable/portable electronics.Herein,by taking inspiration from kirigami,we designed a stretchable supercapacitor(SC)step by step through controlling laser induction and cutting process on the polyimide(PI)film,with the use of one single CO_(2) laser source.Firstly,the carbonized basic geometric units of lines were produced on PI films to investigate the processing-structure relationships.Then,the complex photothermal conversion and heat transfer progress involved in the carbonized process were simulated by a photothermal model.Both experimental and theoretical results suggested that the laser power,scan rate and focus condition have great influence on the size,shape and morphology of the carbonized lines.Finally,we optimized the parameters of laser induction and cutting process to fabricate the kirigami-inspired SCs with reliable electrochemical properties and editable mechanical flexibility,showing great potential in the field of flexible electronics.
基金supported by the National Basic Research Program of China(973 Program,Grant No.2012CB966401)the Key New Drug Creation and Manufacturing Program(Grant No.2011ZX09102-010-03)+1 种基金the National Science and Technology Major Project(Grant No.2013ZX10001003)the Ministry of Science and Technology(Grant No.2011DFA30730 and 2013DFG30680)and 111 Project
文摘Pluripotency-associated factors and their rivals, lineage specifiers, have long been consid- ered the determining factors for the identity of pluripotent and differentiated cells, respectively. Therefore, factors that are employed for cellular reprogramming in order to induce pluripotency have been identified mainly from embryonic stem cell （ESC）-enriched and pluripotency-associated factors. Recently, lineage specifiers have been identified to play important roles in orchestrating the process of restoring pluripotency. In this review, we summarize the latest discoveries regarding cell fate conversion using pluripotency-associated factors and lineage specifiers. We highlight the value of the ＂seesaw＂ model in defining cellular identity, opening up a novel scenario to consider pluri- potency and lineage specification.
