Human activities in the marginal zone of the Changtang Plateau(CTP)uninhabited area are important research topics in China and globally.Based on the core-periphery theory of geography,this paper selected three countie...Human activities in the marginal zone of the Changtang Plateau(CTP)uninhabited area are important research topics in China and globally.Based on the core-periphery theory of geography,this paper selected three counties in the marginal zone of the CTP uninhabited area with significant transitional physical geography features and socio-economic conditions as case areas.We used the data set of settlement patches identified by visual interpretation in Google Earth Pro,combining them with field survey data to study the evolution of human settlements on the CTP,the characteristics of settlement layout,and their socio-economic roots.The study found that:(1)Since the democratic reform in Xizang,the production mode of herders on the CTP has transitioned from four-season nomadic herding to cold-season sedentary grazing,warm-season rotational grazing,and then to a combination of sedentary grazing and forage supplementation.In structural changes of grassroots organizations,village boundaries were clarified,grazing ranges were fixed,and settlement systems were formed.(2)On a large scale,the settlement layout on the CTP showed a certain degree of agglomeration in local areas,but the settlements’spatial agglomeration decreased as the observation scale decreased.The settlement size structure matched the typical rank-size rule of rural settlements.(3)The settlement layout of the CTP showed significant traffic lines and dominant location orientation.These orientation characteristics revealed“core-periphery”regional differences.Changes in production conditions,such as artificial grass cultivation and part-time employment,affected the dependence on traditional grazing points.Settlements moved from resource dependence to dependence on multiple elements,such as resources and facilities.The religious,cultural heritage of the sacred mountains,lakes,and temples influenced the settlement layout,leading to clustering in local areas and to group format.This study expands our understanding of the settlement pattern in the marginal zone of uninhabited areas and provides valuable references for advancing the optimization of the CTP human settlement system in the new era.展开更多
A prediction framework based on the evolution of pattern motion probability density is proposed for the output prediction and estimation problem of non-Newtonian mechanical systems,assuming that the system satisfies t...A prediction framework based on the evolution of pattern motion probability density is proposed for the output prediction and estimation problem of non-Newtonian mechanical systems,assuming that the system satisfies the generalized Lipschitz condition.As a complex nonlinear system primarily governed by statistical laws rather than Newtonian mechanics,the output of non-Newtonian mechanics systems is difficult to describe through deterministic variables such as state variables,which poses difficulties in predicting and estimating the system’s output.In this article,the temporal variation of the system is described by constructing pattern category variables,which are non-deterministic variables.Since pattern category variables have statistical attributes but not operational attributes,operational attributes are assigned to them by posterior probability density,and a method for analyzing their motion laws using probability density evolution is proposed.Furthermore,a data-driven form of pattern motion probabilistic density evolution prediction method is designed by combining pseudo partial derivative(PPD),achieving prediction of the probability density satisfying the system’s output uncertainty.Based on this,the final prediction estimation of the system’s output value is realized by minimum variance unbiased estimation.Finally,a corresponding PPD estimation algorithm is designed using an extended state observer(ESO)to estimate the parameters to be estimated in the proposed prediction method.The effectiveness of the parameter estimation algorithm and prediction method is demonstrated through theoretical analysis,and the accuracy of the algorithm is verified by two numerical simulation examples.展开更多
The body channel based wireless power transfer(BC-WPT)method utilizes the human body as the medium to transfer power for bioelectronics,which can achieve a lower transmission loss due to its higher conductivity.Howeve...The body channel based wireless power transfer(BC-WPT)method utilizes the human body as the medium to transfer power for bioelectronics,which can achieve a lower transmission loss due to its higher conductivity.However,except for the channel length,different on-body loca-tions of the transmitter and receiver also influence the power supply performance.This paper fo-cuses on the wrist-to-forehead path to show the potential of BC-WPT for the brain bioelectronics such as the brain computer interface device.The channel characteristics from 10 MHz to 60 MHz are measured by a vector network analyzer(VNA)and a prototype BC-WPT system with differ-ent copper electrodes and the lowest power loss locates between-22 dB and-33 dB.Furthermore,the minimum path loss limit is simulated in Advanced Design System(ADS)software and the low-est optimum path loss can reach nearly-13 dB.Finally,a rectifier circuit is also built at the receiv-er side to harvest d.c.voltage.The results show that the open-circuit voltage(OCV)can reach 1.75 V with the transmitter of 50Ωoutput impedance supplying 5V_(pp)sine voltage at 60 MHz when adopt-ing 1 cm-diameter circular electrodes.展开更多
研究舰艇附近水下爆炸问题对船体结构设计、爆炸冲击损害预测及人员安全保障至关重要。为此,提出改进扩散界面法中的六方程可压多相流模型以解决冲击波条件下热力学状态预测偏差,并为相关抗冲击机理研究与数值方法优化提供支撑。通过引...研究舰艇附近水下爆炸问题对船体结构设计、爆炸冲击损害预测及人员安全保障至关重要。为此,提出改进扩散界面法中的六方程可压多相流模型以解决冲击波条件下热力学状态预测偏差,并为相关抗冲击机理研究与数值方法优化提供支撑。通过引入混合能量校正方程及更精确的气体状态方程改进模型,在非结构网格系统构建数值算法程序,采用基于最小二乘重建和Barth-Jespersen限制器的二阶守恒定律的单调上游中心方案(Monotonic Upstream-centered Scheme for Conservation Laws,MUSCL)-Hancock格式、两相流带接触的Harten-Lax-van Leer(Harten-Lax-van Leer Contact,HLLC)黎曼求解器求解齐次双曲型方程,以Newton-Raphson迭代法求解瞬时压力松弛方程。研究结果表明:混合能量方程校正后,模型模拟流体冲击波速度和界面的结果与欧拉方程精确解高度吻合,解决界面附近数值振荡问题;相较于实验数据,改进型模型相对误差1.13%,准确度提升0.33%,且通过拟合冲击Hugoniot曲线获得更精确的刚性气体状态方程(Stiffened Gas Equation of State,SG-EOS)参数,同时可清晰呈现水下爆炸的冲击波传播、气泡胀缩及坍塌水射流现象,但在气泡界面清晰度、射流精细度上存在缺陷,主要受数值格式极端梯度下耗散特性限制。综上,改进型六方程可压多相流模型有效提升了舰艇附近水下爆炸模拟准确性,为深入研究舰艇抗冲击机理提供重要支撑,也为后续相关数值方法的优化奠定了坚实基础。展开更多
基金The Second Comprehensive Scientific Investigation and Research Project of the Qinghai-Tibet Plateau,No.2019QZKK1007The Strategic Priority Research Program of the Chinese Academy of Sciences,No.XDA20010102。
文摘Human activities in the marginal zone of the Changtang Plateau(CTP)uninhabited area are important research topics in China and globally.Based on the core-periphery theory of geography,this paper selected three counties in the marginal zone of the CTP uninhabited area with significant transitional physical geography features and socio-economic conditions as case areas.We used the data set of settlement patches identified by visual interpretation in Google Earth Pro,combining them with field survey data to study the evolution of human settlements on the CTP,the characteristics of settlement layout,and their socio-economic roots.The study found that:(1)Since the democratic reform in Xizang,the production mode of herders on the CTP has transitioned from four-season nomadic herding to cold-season sedentary grazing,warm-season rotational grazing,and then to a combination of sedentary grazing and forage supplementation.In structural changes of grassroots organizations,village boundaries were clarified,grazing ranges were fixed,and settlement systems were formed.(2)On a large scale,the settlement layout on the CTP showed a certain degree of agglomeration in local areas,but the settlements’spatial agglomeration decreased as the observation scale decreased.The settlement size structure matched the typical rank-size rule of rural settlements.(3)The settlement layout of the CTP showed significant traffic lines and dominant location orientation.These orientation characteristics revealed“core-periphery”regional differences.Changes in production conditions,such as artificial grass cultivation and part-time employment,affected the dependence on traditional grazing points.Settlements moved from resource dependence to dependence on multiple elements,such as resources and facilities.The religious,cultural heritage of the sacred mountains,lakes,and temples influenced the settlement layout,leading to clustering in local areas and to group format.This study expands our understanding of the settlement pattern in the marginal zone of uninhabited areas and provides valuable references for advancing the optimization of the CTP human settlement system in the new era.
文摘A prediction framework based on the evolution of pattern motion probability density is proposed for the output prediction and estimation problem of non-Newtonian mechanical systems,assuming that the system satisfies the generalized Lipschitz condition.As a complex nonlinear system primarily governed by statistical laws rather than Newtonian mechanics,the output of non-Newtonian mechanics systems is difficult to describe through deterministic variables such as state variables,which poses difficulties in predicting and estimating the system’s output.In this article,the temporal variation of the system is described by constructing pattern category variables,which are non-deterministic variables.Since pattern category variables have statistical attributes but not operational attributes,operational attributes are assigned to them by posterior probability density,and a method for analyzing their motion laws using probability density evolution is proposed.Furthermore,a data-driven form of pattern motion probabilistic density evolution prediction method is designed by combining pseudo partial derivative(PPD),achieving prediction of the probability density satisfying the system’s output uncertainty.Based on this,the final prediction estimation of the system’s output value is realized by minimum variance unbiased estimation.Finally,a corresponding PPD estimation algorithm is designed using an extended state observer(ESO)to estimate the parameters to be estimated in the proposed prediction method.The effectiveness of the parameter estimation algorithm and prediction method is demonstrated through theoretical analysis,and the accuracy of the algorithm is verified by two numerical simulation examples.
文摘The body channel based wireless power transfer(BC-WPT)method utilizes the human body as the medium to transfer power for bioelectronics,which can achieve a lower transmission loss due to its higher conductivity.However,except for the channel length,different on-body loca-tions of the transmitter and receiver also influence the power supply performance.This paper fo-cuses on the wrist-to-forehead path to show the potential of BC-WPT for the brain bioelectronics such as the brain computer interface device.The channel characteristics from 10 MHz to 60 MHz are measured by a vector network analyzer(VNA)and a prototype BC-WPT system with differ-ent copper electrodes and the lowest power loss locates between-22 dB and-33 dB.Furthermore,the minimum path loss limit is simulated in Advanced Design System(ADS)software and the low-est optimum path loss can reach nearly-13 dB.Finally,a rectifier circuit is also built at the receiv-er side to harvest d.c.voltage.The results show that the open-circuit voltage(OCV)can reach 1.75 V with the transmitter of 50Ωoutput impedance supplying 5V_(pp)sine voltage at 60 MHz when adopt-ing 1 cm-diameter circular electrodes.
文摘研究舰艇附近水下爆炸问题对船体结构设计、爆炸冲击损害预测及人员安全保障至关重要。为此,提出改进扩散界面法中的六方程可压多相流模型以解决冲击波条件下热力学状态预测偏差,并为相关抗冲击机理研究与数值方法优化提供支撑。通过引入混合能量校正方程及更精确的气体状态方程改进模型,在非结构网格系统构建数值算法程序,采用基于最小二乘重建和Barth-Jespersen限制器的二阶守恒定律的单调上游中心方案(Monotonic Upstream-centered Scheme for Conservation Laws,MUSCL)-Hancock格式、两相流带接触的Harten-Lax-van Leer(Harten-Lax-van Leer Contact,HLLC)黎曼求解器求解齐次双曲型方程,以Newton-Raphson迭代法求解瞬时压力松弛方程。研究结果表明:混合能量方程校正后,模型模拟流体冲击波速度和界面的结果与欧拉方程精确解高度吻合,解决界面附近数值振荡问题;相较于实验数据,改进型模型相对误差1.13%,准确度提升0.33%,且通过拟合冲击Hugoniot曲线获得更精确的刚性气体状态方程(Stiffened Gas Equation of State,SG-EOS)参数,同时可清晰呈现水下爆炸的冲击波传播、气泡胀缩及坍塌水射流现象,但在气泡界面清晰度、射流精细度上存在缺陷,主要受数值格式极端梯度下耗散特性限制。综上,改进型六方程可压多相流模型有效提升了舰艇附近水下爆炸模拟准确性,为深入研究舰艇抗冲击机理提供重要支撑,也为后续相关数值方法的优化奠定了坚实基础。
