The influence of the longitudinal acceleration and the angular acceleration of detecting target based on vortex electromagnetic waves in keyhole space are analyzed.The spectrum spreads of different orbital angular mom...The influence of the longitudinal acceleration and the angular acceleration of detecting target based on vortex electromagnetic waves in keyhole space are analyzed.The spectrum spreads of different orbital angular momentum(OAM)modes in different non-line-of-sight situations are simulated.The errors of target accelerations in detection are calculated and compared based on the OAM spectra spreading by using two combinations of composite OAM modes in the keyhole space.According to the research,the effects about spectrum spreads of higher OAM modes are more obvious.The error in detection is mainly affected by OAM spectrum spreading,which can be reduced by reasonably using different combinations of OAM modes in different practical situations.The above results provide a reference idea for investigating keyhole effect when vortex electromagnetic wave is used to detect accelerations.展开更多
Analysis of a four-dimensional displacement vector on the fabric of space-time in the special or general case into two Four-dimensional vectors, according to specific conditions leads to the splitting of the total fab...Analysis of a four-dimensional displacement vector on the fabric of space-time in the special or general case into two Four-dimensional vectors, according to specific conditions leads to the splitting of the total fabric of space-time into a positive subspace-time that represents the space of causality and a negative subspace-time which represents a space without causality, thus, in the special case, we have new transformations for the coordinates of space and time modified from Lorentz transformations specific to each subspace, where the contraction of length disappears and the speed of light is no longer a universal constant. In the general case, we have new types of matric tensor, one for positive subspace-time and the other for negative subspace-time. We also find that the speed of the photon decreases in positive subspace-time until it reaches zero and increases in negative subspace-time until it reaches the speed of light when the photon reaches the Schwarzschild radius.展开更多
Taking the sociopetal space with high using rate and welcomed by visitors in Jingxiu Park of Baoding as the study object,human demands on spatial characteristics and space factors were evaluated by the method of POE,a...Taking the sociopetal space with high using rate and welcomed by visitors in Jingxiu Park of Baoding as the study object,human demands on spatial characteristics and space factors were evaluated by the method of POE,and modification measures of the sociopetal space in city opening park were put forward,which provided evidence for solving regional problems of city park and creating urban open space.展开更多
Based on an available parking space occupancy （APSO） survey conducted in Nanjing, China, an APSO forecasting model is proposed. The APSO survey results indicate that the time series of APSO with different time-secti...Based on an available parking space occupancy （APSO） survey conducted in Nanjing, China, an APSO forecasting model is proposed. The APSO survey results indicate that the time series of APSO with different time-sections are periodical and self-similar, and the fluctuation of the APSO increases with the decrease in time-sections. Taking the short-time change behavior into account, an APSO forecasting model combined wavelet analysis and a weighted Markov chain is presented. In this model, an original APSO time series is first decomposed by wavelet analysis, and the results include low frequency signals representing the basic trends of APSO and several high frequency signals representing disturbances of the APSO. Then different Markov models are used to forecast the changes of low and high frequency signals, respectively. Finally, integrating the predicted results induces the final forecasted APSO. A case study verifies the applicability of the proposed model. The comparisons between measured and forecasted results show that the model is a competent model and its accuracy relies on real-time update of the APSO database.展开更多
目的:对比三维多回波恢复梯度回波(3D MERGE)、三维可变反转角快速自旋回波(3D SPACE STIR)序列在腰椎间盘突出症(LDH)检查中的应用效果。方法:选择2020年1月~2022年11月收治的135例LDH患者,回顾性分析患者临床和磁共振成像(MRI)资料,...目的:对比三维多回波恢复梯度回波(3D MERGE)、三维可变反转角快速自旋回波(3D SPACE STIR)序列在腰椎间盘突出症(LDH)检查中的应用效果。方法:选择2020年1月~2022年11月收治的135例LDH患者,回顾性分析患者临床和磁共振成像(MRI)资料,所有患者均接受常规MRI扫描及3D MERGE、3D SPACE STIR序列扫描,对比3D MERGE、3D SPACE STIR序列测量神经根直径的一致性,评价两种序列的图像质量参数[信噪比(SNR)、对比噪声比(CNR)]、图像清晰度评分。结果:3D MERGE和3D SPACE STIR序列测量的L3~S1神经根直径比较差异无统计学意义(P>0.05),且两组序列测量的L3、L4、L5和S1直径均显示出较高相关性(r=0.957,0.986,0.975,0.972,P<0.05);3D MERGE序列的SNR及CNR均高于3D SPACE STIR序列,神经根显示分级、图像清晰度评分优于3D SPACE STIR序列,差异有统计学意义(P<0.05)。结论:3D MERGE、3D SPACE STIR序列在LDH神经根直径测量中具有极高一致性,3D MERGE序列较3D SPACE STIR序列能够更清晰显示神经跟的解剖形态,图像质量更好。展开更多
目的研究血清CC型趋化因子2(CC type chemotactic factor 2,CCL2)、CCL18与声门型喉癌患者临床病理参数和预后的关系。方法选择邯郸市中心医院和河北工程大学附属医院2015年8月~2018年12月收治的168例声门型喉癌患者为研究对象,受试者...目的研究血清CC型趋化因子2(CC type chemotactic factor 2,CCL2)、CCL18与声门型喉癌患者临床病理参数和预后的关系。方法选择邯郸市中心医院和河北工程大学附属医院2015年8月~2018年12月收治的168例声门型喉癌患者为研究对象,受试者工作特征(ROC)曲线确定血清CCL2、CCL18最佳截点,将患者分为CCL2高表达组和低表达组、CCL18高表达组和低表达组,分析血清CCL2、CCL18水平与声门型喉癌患者临床病理参数的关系,采用Kaplan-Meier曲线和Log-Rankχ^(2)检验分析血清CCL2高表达组和低表达组、CCL18高表达组和低表达组的5年无病生存率,采用Cox回归模型分析声门型喉癌预后的影响因素,并分析血清CCL2和CCL18表达与肿瘤复发/转移的关系。结果根据ROC曲线计算得出CCL2、CCL18的最佳截点分别为100.81、218.99 pg/ml。相较于CCL2、CCL18低表达组,CCL2、CCL18高表达组T3~T4a级、N1~N3级、肿瘤低分化占比明显升高(P<0.05)。168例声门型喉癌患者随访5年失访8例,完成随访160例。67例发生复发/转移,39例因复发/转移而死亡,肿瘤复发/转移率为41.88%(67/160),无病生存率为58.13%(93/160)。Kaplan-Meier生存曲分析显示,血清CCL2、CCL18高表达组5年无病生存率均明显低于血清CCL2、CCL18低表达组(P<0.05)。Cox回归分析显示,T分级升高、颈淋巴结复发、N分级升高、咽喉部复发、CCL2高表达、CCL18高表达是声门型喉癌预后不良的危险因素(P<0.05)。分析血清CCL2和CCL18表达与肿瘤复发/转移的关系发现,CCL2和CCL18均高表达时其复发/转移率明显高于CCL2和CCL18均低表达、CCL2低表达且CCL18高表达、CCL2高表达且CCL18低表达,差异比较有统计学意义(χ^(2)=10.450,P=0.015)。结论声门型喉癌患者血清CCL2、CCL18高表达与T分级、N分级、肿瘤低分化和预后不良显著相关。展开更多
针对控制目标耦合导致统一电能质量调节器电能质量补偿响应速度慢、精度差、鲁棒性差等问题,提出了一种控制目标解耦的连续集模型预测(continuous control set model predictive control,CCS-MPC)直接控制策略。该控制策略依据当前时刻...针对控制目标耦合导致统一电能质量调节器电能质量补偿响应速度慢、精度差、鲁棒性差等问题,提出了一种控制目标解耦的连续集模型预测(continuous control set model predictive control,CCS-MPC)直接控制策略。该控制策略依据当前时刻被控目标电压、电流参数,构建目标唯一的预测控制模型,在简化控制器结构的同时实现串、并联侧电感电流和电容电压解耦控制,显著提高统一电能质量调节器动态性能。基于偏导数获取模型预测控制价值函数的最优解,实现参数变化、外部扰动工况下负载电压、电网电流高精度补偿。仿真验证了所提控制策略的有效性。展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11804073 and 61775050).
文摘The influence of the longitudinal acceleration and the angular acceleration of detecting target based on vortex electromagnetic waves in keyhole space are analyzed.The spectrum spreads of different orbital angular momentum(OAM)modes in different non-line-of-sight situations are simulated.The errors of target accelerations in detection are calculated and compared based on the OAM spectra spreading by using two combinations of composite OAM modes in the keyhole space.According to the research,the effects about spectrum spreads of higher OAM modes are more obvious.The error in detection is mainly affected by OAM spectrum spreading,which can be reduced by reasonably using different combinations of OAM modes in different practical situations.The above results provide a reference idea for investigating keyhole effect when vortex electromagnetic wave is used to detect accelerations.
文摘Analysis of a four-dimensional displacement vector on the fabric of space-time in the special or general case into two Four-dimensional vectors, according to specific conditions leads to the splitting of the total fabric of space-time into a positive subspace-time that represents the space of causality and a negative subspace-time which represents a space without causality, thus, in the special case, we have new transformations for the coordinates of space and time modified from Lorentz transformations specific to each subspace, where the contraction of length disappears and the speed of light is no longer a universal constant. In the general case, we have new types of matric tensor, one for positive subspace-time and the other for negative subspace-time. We also find that the speed of the photon decreases in positive subspace-time until it reaches zero and increases in negative subspace-time until it reaches the speed of light when the photon reaches the Schwarzschild radius.
文摘Taking the sociopetal space with high using rate and welcomed by visitors in Jingxiu Park of Baoding as the study object,human demands on spatial characteristics and space factors were evaluated by the method of POE,and modification measures of the sociopetal space in city opening park were put forward,which provided evidence for solving regional problems of city park and creating urban open space.
基金The National Natural Science Foundation of China(No50738001)the National Basic Research Program of China (973Program) (No2006CB705501)
文摘Based on an available parking space occupancy （APSO） survey conducted in Nanjing, China, an APSO forecasting model is proposed. The APSO survey results indicate that the time series of APSO with different time-sections are periodical and self-similar, and the fluctuation of the APSO increases with the decrease in time-sections. Taking the short-time change behavior into account, an APSO forecasting model combined wavelet analysis and a weighted Markov chain is presented. In this model, an original APSO time series is first decomposed by wavelet analysis, and the results include low frequency signals representing the basic trends of APSO and several high frequency signals representing disturbances of the APSO. Then different Markov models are used to forecast the changes of low and high frequency signals, respectively. Finally, integrating the predicted results induces the final forecasted APSO. A case study verifies the applicability of the proposed model. The comparisons between measured and forecasted results show that the model is a competent model and its accuracy relies on real-time update of the APSO database.
文摘目的:对比三维多回波恢复梯度回波(3D MERGE)、三维可变反转角快速自旋回波(3D SPACE STIR)序列在腰椎间盘突出症(LDH)检查中的应用效果。方法:选择2020年1月~2022年11月收治的135例LDH患者,回顾性分析患者临床和磁共振成像(MRI)资料,所有患者均接受常规MRI扫描及3D MERGE、3D SPACE STIR序列扫描,对比3D MERGE、3D SPACE STIR序列测量神经根直径的一致性,评价两种序列的图像质量参数[信噪比(SNR)、对比噪声比(CNR)]、图像清晰度评分。结果:3D MERGE和3D SPACE STIR序列测量的L3~S1神经根直径比较差异无统计学意义(P>0.05),且两组序列测量的L3、L4、L5和S1直径均显示出较高相关性(r=0.957,0.986,0.975,0.972,P<0.05);3D MERGE序列的SNR及CNR均高于3D SPACE STIR序列,神经根显示分级、图像清晰度评分优于3D SPACE STIR序列,差异有统计学意义(P<0.05)。结论:3D MERGE、3D SPACE STIR序列在LDH神经根直径测量中具有极高一致性,3D MERGE序列较3D SPACE STIR序列能够更清晰显示神经跟的解剖形态,图像质量更好。
文摘针对控制目标耦合导致统一电能质量调节器电能质量补偿响应速度慢、精度差、鲁棒性差等问题,提出了一种控制目标解耦的连续集模型预测(continuous control set model predictive control,CCS-MPC)直接控制策略。该控制策略依据当前时刻被控目标电压、电流参数,构建目标唯一的预测控制模型,在简化控制器结构的同时实现串、并联侧电感电流和电容电压解耦控制,显著提高统一电能质量调节器动态性能。基于偏导数获取模型预测控制价值函数的最优解,实现参数变化、外部扰动工况下负载电压、电网电流高精度补偿。仿真验证了所提控制策略的有效性。
