Cycle-by-Cycle Queue Length Estimation for Signalized Intersections Using Multi-Source Data

In order to estimate vehicular queue length at signalized intersections accurately and overcome the shortcomings and restrictions of existing studies especially those based on shockwave theory,a new methodology is presented for estimating vehicular queue length using data from both point detectors and probe vehicles. The methodology applies the shockwave theory to model queue evolution over time and space. Using probe vehicle locations and times as well as point detector measured traffic states,analytical formulations for calculating the maximum and minimum( residual) queue length are developed. The proposed methodology is verified using ground truth data collected from numerical experiments conducted in Shanghai,China. It is found that the methodology has a mean absolute percentage error of 17. 09%,which is reasonably effective in estimating the queue length at traffic signalized intersections. Limitations of the proposed models and algorithms are also discussed in the paper.

Highly active CoP-CO_(2)N confined in nanocarbon enabling efficient electrocatalytic immobilizing-conversion of polysulfide targeting high-rate lithium-sulfur batteries

Lithium-sulfur batteries suffer from poor cycling stability because of the intrinsic shuttling effect of intermediate polysulfides and sluggish reaction kinetics,especially at high rates and high sulfur loading.Herein,we report the construction of a CoP-CO_(2)N@N-doped carbon polyhedron uniformly anchored on three-dimensional carbon nanotubes/graphene(CoP-CO_(2)N@NC/CG)scaffold as a sulfur reservoir to achieve the trapping-diffusion-conversion of polysulfides.Highly active CoP-CO_(2)N shows marvelous catalytic effects by effectively accelerating the reduction of sulfur and the oxidation of Li_(2)S during the discharging and charging process,respectively,while the conductive NC/CG network with massive mesoporous channels ensures fast and continuous long-distance electron/ion transportation.DFT calculations demonstrate that the CoP-CO_(2)N with excellent intrinsic conductivity serves as job-synergistic immobilizing-conversion sites for polysulfides through the formation of P…Li/N…Li and Co…S bonds.As a result,the S@CoP-CO_(2)N@NC/CG cathode(sulfur content 1.7 mg cm^(-2))exhibits a high capacity of988 mAh g^(-1)at 2 C after 500 cycles,which is superior to most of the electrochemical performance reported.Even under high sulfur content(4.3 mg cm^(-2)),it also shows excellent cyclability with high capacity at 1 C.

Experimental investigation of Z-pinch radiation source for indirect drive inertial confinement fusion

Z-pinch dynamic hohlraums(ZPDHs)could potentially be used to drive inertial confinement fusion targets.Double-or multishell capsules using the technique of volume ignition could exploit the advantages of ZPDHs while tolerating their radiation asymmetry,which would be unacceptable for a central ignition target.In this paper,we review research on Z-pinch implosions and ZPDHs for indirect drive targets at the Institute of Nuclear Physics and Chemistry,China Academy of Engineering Physics.The characteristics of double-shell targets and the associated technical requirements are analyzed through a one-dimensional computer code developed from MULTI-IFE.Some key issues regarding the establishment of suitable sources for dynamic hohlraums are introduced,such as soft X-ray power optimization,novel methods for plasma profile modulation,and the use of thin-shell liner implosions to inhibit the generation of prior-stagnated plasma.Finally,shock propagation and radiation characteristics in a ZPDH are presented and discussed,together with some plans for future work.

Evaluation of Major Factors Affecting Spatial Resolution of Gamma-Rays Camera

The spatial resolution of the gamma-rays camera was measured on a60Co gamma-rays source with edge method. The gamma-rays camera is consisting with rays-fluorescence convertor, optical imaging system, MCP image intensifier, CCD camera, electronic control system and other devices, and is mainly used in the image diagnostics of the intense pulse radiation sources [1]. Due to the relatively big quantum detective efficiency (DQE) and quantum gain of the gamma-rays, etc., the experimental data were processed by averaging multiple images and fitting curves. According to the experimental results, the spatial resolution MTF (modulation transfer function) at the 10% intensity was about 2lp/mm. Meanwhile, because of the relatively big dispersion effects of the fluorescence transmissions in the scintillator and the optical imaging system, the maximal single-noise ratio (SNR) of the camera was found to be about 5:1. In addition, the spatial resolution of the camera was measured with pulse X-rays with 0.3MeV in average energy and exclusion of the effects of secondary electrons from consideration. Accordingly, the spatial resolution MTF at the 10% intensity was about 5lp/mm. This could be an additional evidence to verify the effects of secondary electrons induced by the 1.25MeV gamma-rays in the scintillator upon the spatial resolution. Based on our analysis, the dispersion sizes of the secondary electrons in the scintillator are about 0.4mm-0.6mm. Comparatively, as indicated by the detailed analysis of the spatial resolutions of the MCP image intensifier and CCD devices, both of them have little effect on the spatial resolution of the gamma-rays camera that could be well neglected.

Performance Evaluation of the Thick Pinhole Gamma Rays Diagnostic System

The diagnostic methods for the profile of the radiation source were estab-lished at first based on the pinhole imaging principle. In this paper, the relationships among various parameters of the gamma-rays crammer such as the modulation transfer function (MTF), the noise power spectrum (NPS), the signal-noise ratio (SNR) and the detective quantum efficiency (DQE) are developed and studied experimentally on the cobalt radiation source. The image diagnostic system is consisting with rays-fluorescence convertor (YAG crystal), optical imaging system, MCP image intensifier, CCD camera and other devices. The spatial resolution of the modulation transfer function (MTF) at 10% intensity was measured as 1 lp/mm by knife-edge method. The quantum of the measurement system is about 150 under weak radiation condition due to the single particle detection efficiency of the system. The dynamic range was inferred preliminarily as about 437. The required radiation intensity was calculated using the experiment result for the (SNR) = 1, 5, 10, respectively. The theoretical investigation results show that the radiation image with (SNR) = 1 can be only obtained when the pinhole diameter is 0.7 mm, object distance and image distance are both 200 cm, and the radiation intensity is about 1.0 × 1012 Sr-1·cm-2.

Study of Supper Resolution Processing Methods for Thick Pinhole Image

An image super resolution reconstruction method was used to improve the spatial resolution of the thick pinhole imaging system and to mitigate the limitations of the image spatial resolution of the hardware of the image diagnostic system. The thick pinhole is usually applied into the diagnostics of the high energy neutron radiation image. Due to the impacts among its energy flux, spatial resolution and effective field of view, in dealing with the large area radiation source, the spatial resolution of the thick pinhole neutron image cannot meet the requirements for high precision modeling of the radiation source image. In this paper, the Lucy-Richardson image super resolution reconstruction method was used to simulate the thick pinhole imaging and super resolution image reconstruction. And the spatial resolution of the image could be increased by over three times after the image super resolution reconstruction. Besides, in dealing with the pseudo-noise, plum blossom shape appeared in the image super resolution reconstruction. The analysis of the source of the pseudo-noise was made based on the simulation of the image reconstruction under various conditions according to the characteristics of the thick pinhole image configuration.

渣层对中间包内宏观流动及渣/钢界面附近速度的影响

中间包渣层对内部宏观流动的影响往往被忽略,且针对中间包渣/钢界面下方速度的研究较少。本工作以单流无控流装置中间包为研究对象,在水模型中使用墨水和盐水示踪剂研究宏观流动现象,并使用粒子图像测速(PIV)技术测定水油界面下方以及中间包内部区域的速度分布,从而探究油层对中间包内宏观流动以及水油界面处流场的影响。结果表明,油层对中间包内示踪剂在底部的传输和扩散有促进作用,油层的存在减缓了水油界面处墨水传输过程。无油层方案中墨水向上传输趋势明显,而含油层方案中墨水主要沿底部进行传输,与无油层方案相比,墨水从出口流出的时间有所缩短。在盐水示踪剂实验中,含油层方案的RTD曲线相比无油层方案整体向左偏移,盐水溶液较早地流出中间包出口。对于整体流场,无油层方案的速度基本都大于含油层方案速度。在靠近出口和右侧壁面的区域,存在局部速度含油方案略大于无油方案的情况,油层对流体的阻滞作用变弱。对于油层方案,靠近长水口区域的垂直速度最大,随着与水油界面距离增加,垂直速度有所增加。在靠近右侧壁面的区域中,水平速度最大,但其随液面高度变化较小。

CA-YOLOv5: Detection model for healthy and diseased silkworms in mixed conditions based on improved YOLOv5

The accurate identification and localization of diseased silkworms is an important task in the research of disease precision control technology and equipment development in the sericulture industry. However, the existing deep learning-based methods for this task are mainly based on image classification, which fails to provide the location information of diseased silkworms. To this end, this study proposed an object detection-based method for identifying and locating healthy and diseased silkworms. Images of mixed healthy and diseased silkworms were collected using a mobile phone, and the category and location of each silkworm were labeled using LabelImg as a labeling tool to construct an image dataset for object detection. Based on the one-step detection model YOLOv5s, the ConvNeXt-Attention-YOLOv5 (CA-YOLOv5) model was designed in which the large kernel with depth-wise separable convolution (7×7 dw-conv) of ConvNeXt was adopted to expand receptive fields and the channel attention mechanism ECANet was added to enhance the capability of feature extraction. Experiments showed that the mean average precision (mAP) values of CA-YOLOv5 for healthy and diseased silkworms reached 96.46%, which is 1.35% better than that achieved via YOLOv5s. At the same time, the overall performance of CA-YOLOv5 was significantly better than state-of-the-art one-step models, such as Single Shot MultiBox Detector (SSD), CenterNet, and EfficientDet, and even improved YOLOv5 using image attention mechanism and a lightweight backbone, like SENet-YOLOv5 and MobileNet-YOLOv5. The results of this study can provide an important basis for the accurate positioning of diseased silkworms in precision disease control technology and equipment development.

中间包水模型数据的流出百分比分析方法

针对已有停留时间分布曲线或F曲线分析方法在归一化过程中,将单流中间包流出百分比或多流中间包中各流流出百分比之和限定为100%,将示踪剂流出总量信息掩盖,导致结果不精确的问题,本工作提出了流出百分比的分析方法,通过计算可以将物理实验结果转化为各流实时的流出百分比曲线。以流出百分比曲线为基础,计算得到时间加权平均方差和剩余示踪剂百分比,并以此对单流、四流中间包水模型实验结果进行分析。结果表明,采用流出百分比方法能对实验结果进行校对,进一步验证实验的可重复性。同时可对比双挡墙和U型挡墙控制装置设置下,四流中间包监测时间终点流出百分比差异及两倍理论停留时间时刻的死区比例大小。并可直观对比多流中间包不同挡墙下各流的一致性,及在单流堵塞后示踪剂在其他各流的分配及一致性。

Evaluation of urban redevelopment impact on non-motorized traffic

As an important component of city evolution, urban land redevelopment has an impact on transportation system. The current traffic impact analysis （TIA） is lack of a comprehensive component for non-motorized transportation under redevelopment. For a better guidance of land redevelopment and non-motorized transportation planning, it is necessary to evaluate the negative impact of redevelopment on non-motorized traffic in the TIA. In this paper, an evaluation framework for the impact analysis is built up. We organized the pro- cedures and components of impact evaluation, and proposed the corresponding qualitative and quantitative evaluation indicators for non-motorized traffic under redevelopment. Level of service （LOS） and its criterion are employed for external impact evaluation, and level of safety, convenience, independence, and comfort which are four aspects of quality of service （QOS） are proposed to analyze the internal impact. The framework is applied to a redevelopment study in Shanghai, China. The case study results indicate that the rede- velopment from a residential area to a mixed commercial area has a significant impact on non-motorized traffic. The potential negative impact from both external and internal traffic can be minimized by reasonable improvements in the internal land use design.