An analysis is presented for target tracking with short range multistatic radar system in this paper. The velocity vector is introduced into the model to depict target motion more precisely. The system measurement equ...An analysis is presented for target tracking with short range multistatic radar system in this paper. The velocity vector is introduced into the model to depict target motion more precisely. The system measurement equation is such constructed on the basis of range difference that make the tracking model independent of the transmitter position. Therefore the algorithm is very much suitable for the case that the transmitter is not fixed. Simulation results show that the algorithm has the advantages of fast tracking and small steady tracking errors, and can be used for tracking target in short range with multistatic radar system.展开更多
This paper describes a short range target location system based on the range difference information of a T-R4 multistatic radar system with FMCW signal. A new method is proposed to determine the location and length of...This paper describes a short range target location system based on the range difference information of a T-R4 multistatic radar system with FMCW signal. A new method is proposed to determine the location and length of a thin cylindrical target making use of the high resolution of wide band FMCW signal and the spectrum characteristics of the target echo. Formulae are derived for target location and its length estimation being independent of the transmitter position. System performances are simulated with the proposed algorithm and the results are given for various situations.展开更多
The mean shift tracker has difficulty in tracking fast moving targets and suffers from tracking error accumulation problem. To overcome the limitations of the mean shift method, a new approach is proposed by integrati...The mean shift tracker has difficulty in tracking fast moving targets and suffers from tracking error accumulation problem. To overcome the limitations of the mean shift method, a new approach is proposed by integrating the mean shift algorithm and frame-difference methods. The rough position of the moving tar- get is first located by the direct frame-difference algorithm and three-frame-difference algorithm for the immobile camera scenes and mobile camera scenes, respectively. Then, the mean shift algorithm is used to achieve precise tracking of the target. Several tracking experiments show that the proposed method can effectively track first moving targets and overcome the tracking error accumulation problem.展开更多
This paper presents an investigation on the effect of JPEG compression on the similarity between the target image and the background,where the similarity is further used to determine the degree of clutter in the image...This paper presents an investigation on the effect of JPEG compression on the similarity between the target image and the background,where the similarity is further used to determine the degree of clutter in the image.Four new clutter metrics based on image quality assessment are introduced,among which the Haar wavelet-based perceptual similarity index,known as HaarPSI,provides the best target acquisition prediction results.It is shown that the similarity between the target and the background at the boundary between visually lossless and visually lossy compression does not change significantly compared to the case when an uncompressed image is used.In future work,through subjective tests,it is necessary to check whether this presence of compression at the threshold of just noticeable differences will affect the human target acquisition performance.Similarity values are compared with the results of subjective tests of the well-known target Search_2 database,where the degree of agreement between objective and subjective scores,measured through linear correlation,reached a value of 90%.展开更多
The existing research results show that a fixed single station must conduct three consecutive frequency shift measurements and obtain the target’s moving speed by constructing two frequency difference equations. This...The existing research results show that a fixed single station must conduct three consecutive frequency shift measurements and obtain the target’s moving speed by constructing two frequency difference equations. This article proposes a new method that requires only two consecutive measurements. While using the azimuth measurement to obtain the angular difference between two radial distances, it also conducts two consecutive Doppler frequency shift measurements at the same target azimuth. On the basis of this measurement, a frequency difference equation is first constructed and solved jointly with the Doppler frequency shift equation. By eliminating the velocity variable and using the measured angular difference to obtain the target’s lead angle, the target’s velocity can be solved by using the Doppler frequency shift equation again. The new method avoids the condition that the target must move equidistantly, which not only provides an achievable method for engineering applications but also lays a good foundation for further exploring the use of steady-state signals to achieve passive positioning.展开更多
Fusion power output is proportional not only to the fuel particle number densities participating in reaction but also to the fusion reaction rate coefficient (or reactivity), which is dependent on reactant velocity ...Fusion power output is proportional not only to the fuel particle number densities participating in reaction but also to the fusion reaction rate coefficient (or reactivity), which is dependent on reactant velocity distribution functions. They are usuMly assumed to be dual Maxwellian distribution functions with the same temperature for thermal nuclear fusion circumstances. However, if high power neutral beam injection and minority ion species ICRF plasma heating, or multi-pinched plasma beam head-on collision, in a converging region are required and investigated in future large scale fusion reactors, then the fractions of the injected energetic fast ion tail resulting from ionization or charge exchange will be large enough and their contribution to the non-Maxwellian distribution functions is not negligible, hence to the fusion reaction rate coefficient or calculation of fusion power. In such cases, beam-target, and beam-beam reaction enhancement effect contributions should play very important roles. In this paper, several useful formulae to calculate the fusion reaction rate coefticient for different beam and target combination scenarios are derived in detail展开更多
color words may show different cultural connotation of each language in some degree.While translating,we should handle color words appropriately according to cultural differences in both the original and target langua...color words may show different cultural connotation of each language in some degree.While translating,we should handle color words appropriately according to cultural differences in both the original and target language.This paper brings a discussion of cultural differences between English and Chinese color words.展开更多
Small infrared target detection has widespread applications in various fields including military,aviation,and medicine.However,detecting small infrared targets in complex backgrounds remains challenging.To detect smal...Small infrared target detection has widespread applications in various fields including military,aviation,and medicine.However,detecting small infrared targets in complex backgrounds remains challenging.To detect small infrared targets,we propose a variable-structure U-shaped network referred as CAFUNet.A central differential convolution-based encoder,ASPP,an Attention Fusion module,and a decoder module are the critical components of the CAFUNet.The encoder module based on central difference convolution effectively extracts shallow detail information from infrared images,complemented by rich contextual information obtained from the deep features in the decoder module.However,the direct fusion of the shallow detail features with semantic features may lead to feature mismatch.To address this,we incorporate an Attention Fusion(AF)module to enhance the network performance further.We performed ablation studies on each module to evaluate its effectiveness.The results show that our proposed algorithm outperforms the state-of-the-art methods on publicly available datasets.展开更多
基于超高效液相色谱-质谱联用的非靶向代谢组学方法探究不同年龄组驼肉代谢物的差异及变化规律。结果表明,在3个年龄组(3~4、6~7岁和9~10岁,分别以I、II和III组表示)骆驼背最长肌中共鉴定出显著差异代谢物710种;在I vs II组显著差异代...基于超高效液相色谱-质谱联用的非靶向代谢组学方法探究不同年龄组驼肉代谢物的差异及变化规律。结果表明,在3个年龄组(3~4、6~7岁和9~10岁,分别以I、II和III组表示)骆驼背最长肌中共鉴定出显著差异代谢物710种;在I vs II组显著差异代谢物有78个,其中I组上调47个,II组上调31个;在II vs III组显著差异代谢物有49个,其中II组上调18个,III组上调31个;在I vs III组显著差异代谢物有65个,其中I组上调29个,III组上调36个。京都基因与基因组百科全书通路分析结果表明,差异代谢物主要富集到蛋白质和氨基酸代谢、脂肪酸、维生素和矿物质代谢等相关通路,说明不同生长阶段骆驼中各营养素的消化代谢均有差异。I组中的多不饱和脂肪酸(polyunsaturated fatty acid,PUFA)(尤其n-6 PUFA、n-3 PUFA)含量和PUFA/不饱和脂肪酸值均显著高于III组,这主要与相关代谢通路上的花生四烯酸、亚油酸和13-L-过氧化氢油酸浓度的显著上调有关;同时L-亮氨酸、L-缬氨酸、L-谷氨酰胺等差异代谢物可以作为不同年龄驼肉品质差异的潜在标记物。展开更多
红外小目标的检测一直是红外追踪系统的关键技术,针对现有红外小目标检测方法在复杂背景下易造成虚警、检测速度慢的不足,从人类视觉系统的角度出发,参考了多尺度局部能量因子检测方法(multiscale local contrast measure using a local...红外小目标的检测一直是红外追踪系统的关键技术,针对现有红外小目标检测方法在复杂背景下易造成虚警、检测速度慢的不足,从人类视觉系统的角度出发,参考了多尺度局部能量因子检测方法(multiscale local contrast measure using a local energy factor,MLCM-LEF),提出了一种基于双层局部能量因子的红外小目标检测方法.从局部能量差异与局部亮度差异两个角度进行目标检测,使用双层局部能量因子从能量角度描述小目标与背景的相异程度,同时采取加权亮度差因子从亮度角度对图像进行目标检测,通过二维高斯融合上述二者的处理结果,最终利用图像均值和标准差进行自适应阈值分割,提取红外小目标.经过公开数据集实验测试,该方法在抑制背景噪声、减低虚警概率的表现上比主流的检测方法有所提升,与MLCM-LEF算法相比,基于双层局部能量因子的方法将单帧检测时间降低至三分之一.展开更多
文摘An analysis is presented for target tracking with short range multistatic radar system in this paper. The velocity vector is introduced into the model to depict target motion more precisely. The system measurement equation is such constructed on the basis of range difference that make the tracking model independent of the transmitter position. Therefore the algorithm is very much suitable for the case that the transmitter is not fixed. Simulation results show that the algorithm has the advantages of fast tracking and small steady tracking errors, and can be used for tracking target in short range with multistatic radar system.
文摘This paper describes a short range target location system based on the range difference information of a T-R4 multistatic radar system with FMCW signal. A new method is proposed to determine the location and length of a thin cylindrical target making use of the high resolution of wide band FMCW signal and the spectrum characteristics of the target echo. Formulae are derived for target location and its length estimation being independent of the transmitter position. System performances are simulated with the proposed algorithm and the results are given for various situations.
基金supported by the Fundamental Research Funds for the Central Universities Project(CDJZR10170010)
文摘The mean shift tracker has difficulty in tracking fast moving targets and suffers from tracking error accumulation problem. To overcome the limitations of the mean shift method, a new approach is proposed by integrating the mean shift algorithm and frame-difference methods. The rough position of the moving tar- get is first located by the direct frame-difference algorithm and three-frame-difference algorithm for the immobile camera scenes and mobile camera scenes, respectively. Then, the mean shift algorithm is used to achieve precise tracking of the target. Several tracking experiments show that the proposed method can effectively track first moving targets and overcome the tracking error accumulation problem.
文摘This paper presents an investigation on the effect of JPEG compression on the similarity between the target image and the background,where the similarity is further used to determine the degree of clutter in the image.Four new clutter metrics based on image quality assessment are introduced,among which the Haar wavelet-based perceptual similarity index,known as HaarPSI,provides the best target acquisition prediction results.It is shown that the similarity between the target and the background at the boundary between visually lossless and visually lossy compression does not change significantly compared to the case when an uncompressed image is used.In future work,through subjective tests,it is necessary to check whether this presence of compression at the threshold of just noticeable differences will affect the human target acquisition performance.Similarity values are compared with the results of subjective tests of the well-known target Search_2 database,where the degree of agreement between objective and subjective scores,measured through linear correlation,reached a value of 90%.
文摘The existing research results show that a fixed single station must conduct three consecutive frequency shift measurements and obtain the target’s moving speed by constructing two frequency difference equations. This article proposes a new method that requires only two consecutive measurements. While using the azimuth measurement to obtain the angular difference between two radial distances, it also conducts two consecutive Doppler frequency shift measurements at the same target azimuth. On the basis of this measurement, a frequency difference equation is first constructed and solved jointly with the Doppler frequency shift equation. By eliminating the velocity variable and using the measured angular difference to obtain the target’s lead angle, the target’s velocity can be solved by using the Doppler frequency shift equation again. The new method avoids the condition that the target must move equidistantly, which not only provides an achievable method for engineering applications but also lays a good foundation for further exploring the use of steady-state signals to achieve passive positioning.
基金Supported by the International Thermonuclear Experimental Reactor Project of China under Grant No 2013GB114003the National Natural Science Foundation of China under Grant No 11275135
文摘Fusion power output is proportional not only to the fuel particle number densities participating in reaction but also to the fusion reaction rate coefficient (or reactivity), which is dependent on reactant velocity distribution functions. They are usuMly assumed to be dual Maxwellian distribution functions with the same temperature for thermal nuclear fusion circumstances. However, if high power neutral beam injection and minority ion species ICRF plasma heating, or multi-pinched plasma beam head-on collision, in a converging region are required and investigated in future large scale fusion reactors, then the fractions of the injected energetic fast ion tail resulting from ionization or charge exchange will be large enough and their contribution to the non-Maxwellian distribution functions is not negligible, hence to the fusion reaction rate coefficient or calculation of fusion power. In such cases, beam-target, and beam-beam reaction enhancement effect contributions should play very important roles. In this paper, several useful formulae to calculate the fusion reaction rate coefticient for different beam and target combination scenarios are derived in detail
文摘color words may show different cultural connotation of each language in some degree.While translating,we should handle color words appropriately according to cultural differences in both the original and target language.This paper brings a discussion of cultural differences between English and Chinese color words.
文摘Small infrared target detection has widespread applications in various fields including military,aviation,and medicine.However,detecting small infrared targets in complex backgrounds remains challenging.To detect small infrared targets,we propose a variable-structure U-shaped network referred as CAFUNet.A central differential convolution-based encoder,ASPP,an Attention Fusion module,and a decoder module are the critical components of the CAFUNet.The encoder module based on central difference convolution effectively extracts shallow detail information from infrared images,complemented by rich contextual information obtained from the deep features in the decoder module.However,the direct fusion of the shallow detail features with semantic features may lead to feature mismatch.To address this,we incorporate an Attention Fusion(AF)module to enhance the network performance further.We performed ablation studies on each module to evaluate its effectiveness.The results show that our proposed algorithm outperforms the state-of-the-art methods on publicly available datasets.
文摘基于超高效液相色谱-质谱联用的非靶向代谢组学方法探究不同年龄组驼肉代谢物的差异及变化规律。结果表明,在3个年龄组(3~4、6~7岁和9~10岁,分别以I、II和III组表示)骆驼背最长肌中共鉴定出显著差异代谢物710种;在I vs II组显著差异代谢物有78个,其中I组上调47个,II组上调31个;在II vs III组显著差异代谢物有49个,其中II组上调18个,III组上调31个;在I vs III组显著差异代谢物有65个,其中I组上调29个,III组上调36个。京都基因与基因组百科全书通路分析结果表明,差异代谢物主要富集到蛋白质和氨基酸代谢、脂肪酸、维生素和矿物质代谢等相关通路,说明不同生长阶段骆驼中各营养素的消化代谢均有差异。I组中的多不饱和脂肪酸(polyunsaturated fatty acid,PUFA)(尤其n-6 PUFA、n-3 PUFA)含量和PUFA/不饱和脂肪酸值均显著高于III组,这主要与相关代谢通路上的花生四烯酸、亚油酸和13-L-过氧化氢油酸浓度的显著上调有关;同时L-亮氨酸、L-缬氨酸、L-谷氨酰胺等差异代谢物可以作为不同年龄驼肉品质差异的潜在标记物。
文摘红外小目标的检测一直是红外追踪系统的关键技术,针对现有红外小目标检测方法在复杂背景下易造成虚警、检测速度慢的不足,从人类视觉系统的角度出发,参考了多尺度局部能量因子检测方法(multiscale local contrast measure using a local energy factor,MLCM-LEF),提出了一种基于双层局部能量因子的红外小目标检测方法.从局部能量差异与局部亮度差异两个角度进行目标检测,使用双层局部能量因子从能量角度描述小目标与背景的相异程度,同时采取加权亮度差因子从亮度角度对图像进行目标检测,通过二维高斯融合上述二者的处理结果,最终利用图像均值和标准差进行自适应阈值分割,提取红外小目标.经过公开数据集实验测试,该方法在抑制背景噪声、减低虚警概率的表现上比主流的检测方法有所提升,与MLCM-LEF算法相比,基于双层局部能量因子的方法将单帧检测时间降低至三分之一.