Numerical simulation for the initial state of avalanche in polydisperse particle systems

Numerical simulation is employed to investigate the initial state of avalanche in polydisperse particle systems.Nucleation and propagation processes are illustrated for pentadisperse and triadisperse particle systems,respectively.In these processes,particles involved in the avalanche grow slowly in the early stage and explosively in the later stage,which is clearly different from the continuous and steady growth trend in the monodisperse system.By examining the avalanche propagation,the number growth of particles involved in the avalanche and the slope of the number growth,the initial state can be divided into three stages:T1(nucleation stage),T2(propagation stage),T3(overall avalanche stage).We focus on the characteristics of the avalanche in the T2 stage,and find that propagation distances increase almost linearly in both axial and radial directions in polydisperse systems.We also consider the distribution characteristics of the average coordination number and average velocity for the moving particles.The results support that the polydisperse particle systems are more stable in the T2 stage.

Impact of initial fluctuations and nuclear deformations in isobar collisions

Relativistic isobar^(96)_(44)Ru+^(96)_(44)Ru and^(96)_(40)Zr+^(96)_(40)Zrcollisions have revealed intricate differences in their nuclear size and shape,inspiring unconventional studies of nuclear structure using relativistic heavy ion collisions.In this study,we investigate the relative differences in the mean multiplicityR_(<Nch>)and the secondR_(ε2)and third-order eccentricityR_(ε3)between isobar collisions using initial state Glauber models.It is found that initial fluctuations and nuclear deformations have negligible effects on R_(<Nch>)in most central collisions,while both are important for the R_(ε2)and R_(ε3),the degree of which is sensitive to the underlying nucleonic or sub-nucleonic degree of freedom.These features,compared to real data,may probe the particle production mechanism and the physics underlying nuclear structure.

An Initial Perturbation Method for the Multiscale Singular Vector in Global Ensemble Prediction

Ensemble prediction is widely used to represent the uncertainty of single deterministic Numerical Weather Prediction(NWP) caused by errors in initial conditions(ICs). The traditional Singular Vector(SV) initial perturbation method tends only to capture synoptic scale initial uncertainty rather than mesoscale uncertainty in global ensemble prediction. To address this issue, a multiscale SV initial perturbation method based on the China Meteorological Administration Global Ensemble Prediction System(CMA-GEPS) is proposed to quantify multiscale initial uncertainty. The multiscale SV initial perturbation approach entails calculating multiscale SVs at different resolutions with multiple linearized physical processes to capture fast-growing perturbations from mesoscale to synoptic scale in target areas and combining these SVs by using a Gaussian sampling method with amplitude coefficients to generate initial perturbations. Following that, the energy norm,energy spectrum, and structure of multiscale SVs and their impact on GEPS are analyzed based on a batch experiment in different seasons. The results show that the multiscale SV initial perturbations can possess more energy and capture more mesoscale uncertainties than the traditional single-SV method. Meanwhile, multiscale SV initial perturbations can reflect the strongest dynamical instability in target areas. Their performances in global ensemble prediction when compared to single-scale SVs are shown to(i) improve the relationship between the ensemble spread and the root-mean-square error and(ii) provide a better probability forecast skill for atmospheric circulation during the late forecast period and for short-to medium-range precipitation. This study provides scientific evidence and application foundations for the design and development of a multiscale SV initial perturbation method for the GEPS.

Mg-doped,carbon-coated,and prelithiated SiO_(x) as anode materials with improved initial Coulombic efficiency for lithium-ion batteries

Silicon suboxide(SiO_(x),x≈1)is promising in serving as an anode material for lithium-ion batteries with high capacity,but it has a low initial Coulombic efficiency(ICE)due to the irreversible formation of lithium silicates during the first cycle.In this work,we modify SiO_(x) by solid-phase Mg doping reaction using low-cost Mg powder as a reducing agent.We show that Mg reduces SiO_(2) in SiO_(x) to Si and forms MgSiO_(3) or Mg_(2)SiO_(4).The MgSiO_(3) or Mg_(2)SiO_(4) are mainly distributed on the surface of SiO_(x),which suppresses the irreversible lithium-ion loss and enhances the ICE of SiO_(x).However,the formation of MgSiO_(3) or Mg_(2)SiO_(4) also sacrifices the capacity of SiO_(x).Therefore,by controlling the reaction process between Mg and SiO_(x),we can tune the phase composition,proportion,and morphology of the Mg-doped SiO_(x) and manipulate the performance.We obtain samples with a capacity of 1226 mAh g^(–1) and an ICE of 84.12%,which show significant improvement over carbon-coated SiO_(x) without Mg doping.By the synergistical modification of both Mg doping and prelithiation,the capacity of SiO_(x) is further increased to 1477 mAh g^(–1) with a minimal compromise in the ICE(83.77%).

Multi-Level Image Segmentation Combining Chaotic Initialized Chimp Optimization Algorithm and Cauchy Mutation

To enhance the diversity and distribution uniformity of initial population,as well as to avoid local extrema in the Chimp Optimization Algorithm(CHOA),this paper improves the CHOA based on chaos initialization and Cauchy mutation.First,Sin chaos is introduced to improve the random population initialization scheme of the CHOA,which not only guarantees the diversity of the population,but also enhances the distribution uniformity of the initial population.Next,Cauchy mutation is added to optimize the global search ability of the CHOA in the process of position(threshold)updating to avoid the CHOA falling into local optima.Finally,an improved CHOA was formed through the combination of chaos initialization and Cauchy mutation(CICMCHOA),then taking fuzzy Kapur as the objective function,this paper applied CICMCHOA to natural and medical image segmentation,and compared it with four algorithms,including the improved Satin Bowerbird optimizer(ISBO),Cuckoo Search(ICS),etc.The experimental results deriving from visual and specific indicators demonstrate that CICMCHOA delivers superior segmentation effects in image segmentation.

Irregular initial solidification by mold thermal monitoring in the continuous casting of steels:A review

Occasional irregular initial solidification phenomena,including stickers,deep oscillation marks,depressions,and surface cracks of strand shells in continuous casting molds,are important limitations for developing the high-efficiency continuous casting of steels.The application of mold thermal monitoring(MTM) systems,which use thermocouples to detect and respond to temperature variations in molds,has become an effective method to address irregular initial solidification phenomena.Such systems are widely applied in numerous steel companies for sticker breakout prediction.However,monitoring the surface defects of strands remains immature.Hence,indepth research is necessary to utilize the potential advantages and comprehensive monitoring of MTM systems.This paper summarizes what is included in the irregular initial solidification phenomena and systematically reviews the current state of research on these phenomena by the MTM systems.Furthermore,the influences of mold slag behavior on monitoring these phenomena are analyzed.Finally,the remaining problems of the formation mechanisms and investigations of irregular initial solidification phenomena are discussed,and future research directions are proposed.

An improved initial rotor position estimation method using high-frequency pulsating voltage injection for PMSM

High frequency pulsating voltage injection method is a good candidate for detecting the initial rotor position of permanent magnet synchronous motor.However,traditional methods require a large number of filters,which leads to the deterioration of system stability and dynamic performance.In order to solve these problems,a new signal demodulation method is proposed in this paper.The proposed new method can directly obtain the amplitude of high-frequency current,thus eliminating the use of filters,improving system stability and dynamic performance and saving the work of adjusting filter parameters.In addition,a new magnetic polarity detection method is proposed,which is robust to current measurement noise.Finally,experiments verify the effectiveness of the method.

Impact of Initial Soil Conditions on Soil Hydrothermal and Surface Energy Fluxes in the Permafrost Region of the Tibetan Plateau

Accurate initial soil conditions play a crucial role in simulating soil hydrothermal and surface energy fluxes in land surface process modeling.This study emphasized the influence of the initial soil temperature(ST)and soil moisture(SM)conditions on a land surface energy and water simulation in the permafrost region in the Tibetan Plateau(TP)using the Community Land Model version 5.0(CLM5.0).The results indicate that the default initial schemes for ST and SM in CLM5.0 were simplistic,and inaccurately represented the soil characteristics of permafrost in the TP which led to underestimating ST during the freezing period while overestimating ST and underestimating SLW during the thawing period at the XDT site.Applying the long-term spin-up method to obtain initial soil conditions has only led to limited improvement in simulating soil hydrothermal and surface energy fluxes.The modified initial soil schemes proposed in this study comprehensively incorporate the characteristics of permafrost,which coexists with soil liquid water(SLW),and soil ice(SI)when the ST is below freezing temperature,effectively enhancing the accuracy of the simulated soil hydrothermal and surface energy fluxes.Consequently,the modified initial soil schemes greatly improved upon the results achieved through the long-term spin-up method.Three modified initial soil schemes experiments resulted in a 64%,88%,and 77%reduction in the average mean bias error(MBE)of ST,and a 13%,21%,and 19%reduction in the average root-mean-square error(RMSE)of SLW compared to the default simulation results.Also,the average MBE of net radiation was reduced by 7%,22%,and 21%.

Effect of Size and Initial Water Content on the Effective Diffusion Coefficient during Convective Drying of Sweet Potato Cut into Cubic and Cylindrical Shapes

In this article, we investigated the influence of size and initial water content on the effective diffusion coefficient of sweet potatoes samples cut into cubic and cylindrical shapes. The sizes of the cubic samples are 0.5, 1, 1.5, 1.75, 2, 2.5 and 3 cm edge with a respective initial water content of 2.7, 3.76, 3.48, 2.68, 3.28, 2.17 and 2.29 kg/kgms. For cylindrical samples, the radius is set at 0.5 cm and sample heights are 1, 1.5, 2, 2.5, 3, 3.5 and 4 cm with respective water contents of 2.2, 3.19, 2.85, 2.1, 2.17, 2.39 and 2.03 kg/kgms. The effective diffusion coefficients of cubic samples are of the order of 10−10 and 10−9 m2∙s−1 grew with sample edge. As for the cylindrical samples, the effective diffusion coefficients were of the order of 10−9 m2∙s−1 and there was no linear correlation between cylinder height and their effective diffusion coefficient. As for the examination of the initial water content on the effective diffusion coefficient, it turned out that the initial water content had no influence on the effective diffusion coefficient of the sweet potato samples.

Influence of initial check, information exchange, final accuracy check, reaction information nursing on the psychology of elderly with lung cancer

BACKGROUND As one of the fatal diseases with high incidence,lung cancer has seriously endangered public health and safety.Elderly patients usually have poor self-care and are more likely to show a series of psychological problems.AIM To investigate the effectiveness of the initial check,information exchange,final accuracy check,reaction(IIFAR)information care model on the mental health status of elderly patients with lung cancer.METHODS This study is a single-centre study.We randomly recruited 60 elderly patients with lung cancer who attended our hospital from January 2021 to January 2022.These elderly patients with lung cancer were randomly divided into two groups,with the control group taking the conventional propaganda and education and the observation group taking the IIFAR information care model based on the conventional care protocol.The differences in psychological distress,anxiety and depression,life quality,fatigue,and the locus of control in psychology were compared between these two groups,and the causes of psychological distress were analyzed.RESULTS After the intervention,Distress Thermometer,Hospital Anxiety and Depression Scale(HADS)for anxiety and the HADS for depression,Revised Piper’s Fatigue Scale,and Chance Health Locus of Control scores were lower in the observation group compared to the pre-intervention period in the same group and were significantly lower in the observation group compared to those of the control group(P<0.05).After the intervention,Quality of Life Questionnaire Core 30(QLQ-C30),Internal Health Locus of Control,and Powerful Others Health Locus of Control scores were significantly higher in the observation and the control groups compared to the pre-intervention period in their same group,and QLQ-C30 scores were significantly higher in the observation group compared to those of the control group(P<0.05).CONCLUSION The IIFAR information care model can help elderly patients with lung cancer by reducing their anxiety and depression,psychological distress,and fatigue,improving their tendencies on the locus of control in psychology,and enhancing their life qualities.

障碍物数量对含尘瓦斯爆炸特性影响的试验和数值模拟研究

为探究含尘瓦斯爆炸条件下不同数量障碍物的激励效应,运用中尺度激波管道和激光纹影系统,对比不同数量障碍物影响下含尘瓦斯爆炸的火焰传播和压力变化,分析爆炸流场结构的变化。通过数值模拟软件Fluent模拟含尘瓦斯爆炸,对试验结论进行补充说明。结果表明,障碍物对爆炸火焰的加速作用在单一瓦斯参与下更加强烈。煤尘的加入使得流场湍流度增大,混合爆炸释放更多能量,激波强度增大,爆炸压力提升。障碍物对火焰的影响仅在其附近有效,障碍物下游最大超压明显提升。随障碍物数量的增加,激波反复振荡、叠加,使得压力升高,湍流度增加,火焰形成射流并加速燃烧。火焰传播速度和最大超压与障碍物数量呈正相关关系。

运动伪影校正技术改善肾动脉瘤锥形束CT图像质量

目的观察运动伪影校正技术(MFT)对于改善肾动脉瘤锥形束CT(CBCT)图像质量的价值。方法前瞻性选取20例拟接受经导管动脉栓塞治疗的肾动脉瘤患者,于CBCT引导下行肾动脉造影,采用MFT处理运动伪影;对MFT校正前、后图像质量进行主、客观评价,评估其显示肾动脉、载瘤动脉及靶区血管树情况,测算单位密度像素平均值(mean)、标准差(SD)及血管边缘锐化误差率。结果MFT校正后,肾动脉瘤最大密度投影图像显示肾动脉、重建CBCT图像显示载瘤动脉均明显优于校正前(P均<0.05);利用Flightplan for Liver软件可自动提取清晰的血管树;肾动脉瘤CBCT图像SD及血管边缘锐化误差率明显减小而mean明显增加(P均<0.05)。结论MFT可有效改善肾动脉瘤CBCT图像质量。

基于探测器响应机理的碳/碳构件CT图像环状伪影的校正方法

在碳/碳复合材料的计算机断层扫描(CT)中,由于探测器单元的响应非线性及不一致性导致重建图像出现严重的环状伪影,干扰图像中缺陷的检出,影响检测系统对被检构件的质量评价。结合碳/碳复合材料组分单一且密度均匀的特点,提出了一种基于探测器响应机理的CT图像环状伪影的校正方法,利用采集的劣化投影数据做预重建,对重建结果做阈值分割以获得被检测物体的三维模型。结合已知的材料和密度信息,对被检物体进行重投影,得到投影数据的理论值与实测值之间的映射关系,用于探测器响应校正以优化检测图像。与传统低通滤波的环状伪影校正方法相比,该方法考虑了环状伪影的物理成因并充分利用了检测对象的先验信息。研究结果表明,该校正方法在保留图像细节和纹理的同时,能够有效减少环状伪影,提升图像质量,消除伪影对于图形中缺陷识别的干扰,为提升检测系统对碳/碳复合材料构件缺陷的检出能力提供理论依据。

基于纹影成像技术的可视化口罩密合性检测装置的设计与应用

口罩佩戴不当造成的泄漏会显著降低口罩的有效性。现有的口罩密合性测试结果仅判断佩戴口罩过程中是否存在气体泄漏,但无法精确指出气流泄露部位,也不能实时调整口罩佩戴方式。为此,利用纹影成像技术设计口罩密合性检测装置。该技术利用气流对光波的扰动,将肉眼看不到的气流变化转化为可见的图像,从而实现气流的可视化。利用口罩密合性检测装置可观测不同口罩、不同佩戴个体下的口罩气流泄露情况,同时测量泄露气流的纹影面积。使用该装置测试头模或真人佩戴口罩时的密合性,结果显示:头模佩戴医用外科口罩时泄露气流的纹影最明显;不同个体佩戴同类口罩时泄露气流也存在纹影差异。采用医用外科口罩对装置有效性进行验证,数据显示正确佩戴口罩时口罩边缘气流泄漏率为36.83%。

脑血管数字减影血管造影高分辨率分割网络设计

针对现存卷积神经网络对脑血管数字减影血管造影分割精度不高的问题,本文提出了一种基于U-Net的改进网络(IC-Net)。通过融合使用Inception和CAM通道注意力模块,以多种感受域提取更丰富的血管特征信息,并对特征信息进行筛选。增加7×7卷积层,通过压缩特征层分辨率的方式减少训练过程中产生的数据量。本文所提模型与U-Net、R2U-Net、Attention U-Net相比,IOU、Accuracy、F1-Score和ROC曲线下面积4项指标平均提升了1.82%、0.014%、1.19%和0.73%。结果验证了IC-Net模型明显提升了脑血管数字减影血管造影虚弱血管和血管末端的检测能力,提升了分辨伪影噪声的能力,为医生识别脑血管中产生的病变提供有力参考。

能谱CT去金属伪影技术对髋关节置换患者置换物伪影及成像质量效果影响研究

目的 探循能谱CT去金属伪影(MAR)技术对髋关节置换患者置换物伪影及成像质量效果影响研究。方法回顾性研究,纳入首都医科大学附属北京友谊医院于2022年1月至2023年10月收治的42例髋关节置换患者为研究对象,均应用CT能谱及MAR技术,基于原始能谱CT扫描数据,权定能级范围70~130keV,并以20keV能级为间隔(依次为70keV、90keV、110keV及130keV),共计4组,所获单能量图像按MAR技术使用有无分为非MAR组、MAR组。观察两组置换物周围肌肉、周围骨组织、膀胱在相同能级下的信噪比(SNR)及伪影指数(AI)用以评估伪影情况,且由2名高年资影像医师对置换物周围肌肉、骨质结构及盆腔器官情况进行主观评分用以评估成像质量效果。结果 随能级升高,两组置换物周围肌肉、周围骨组织、膀胱SNR均有升高,AI均有降低,且在70~110KeV能级条件下,MAR组置换物周围肌肉、周围骨组织SNR均高于非MAR组,AI均低于非MAR组,差异有统计学意义(P<0.05),在70~130KeV能级条件下,MAR组膀胱SNR均高于非MAR组,AI均低于非MAR组,差异有统计学意义(P<0.05);随能级升高,非MAR组周围肌肉、盆腔器官主观评分先升后降,于110KeV抵达最高值,骨质结构主观评分逐步升高,MA R周围肌肉、骨质结构及盆腔器官情况主观评分均逐步升高,于70keV、90keV、110keV及130keV相同能级下,相较于非MAR组,MAR周围肌肉、骨质结构及盆腔器官情况主观评分均更高(P<0.05)。结论 髋关节置换患者应用能谱CT联合MAR技术,置换物伪影得以减少,成像质量效果获有提高,推荐在110KeV能级水平上采用MAR技术,可最大限度消除金属伪影,并充分显示临近组织,更有助于临床诊断。

影响乳腺X线导管造影图像质量的因素分析及处理对策

目的对影响乳腺X线导管造影图像质量的因素进行调查收集,总结常发生的问题并提出处理对策,为临床提供能满足诊治要求的导管造影图像。方法回顾性收集2016年1月—2019年12月我院行乳腺X线导管造影检查的资料,检查成功的共有2850例,其中一次性成功者2609例,进行二次检查的导管造影的病例241例,对比两次造影检查的过程与图像质量。结果影响导管造影图像质量或造成造影术失败的常见原因有8大类,导管内容物干扰导管的显示最多,有70例;导管内空气造成的伪影有43例;注入对比剂过多有36例;注入对比剂过少有29例;拍片时压力过大有25例;呼吸运动伪影有20例;对比剂误入其他导管有14例;其他原因有4例。针对不同的原因与高年资技师、诊断医师分析并找出应对方法,获得满足临床诊治的图像。结论乳腺X线导管造影的图像质量好坏,影响临床对导管内有无病变的诊断,耽误患者病情的治疗,技师应针对不同的情况采取相适宜的应对方法,可以有效解决造影失败问题,提升乳腺导管造影成功率,提高导管造影图像质量,满足临床诊治所需。

阻塞性睡眠呼吸暂停综合征患儿面部形态和舌骨位置的头影测量研究

目的分析阻塞性睡眠呼吸暂停综合征(OSAS)患儿面部形态和舌骨位置的头影测量指标结果。方法随机选取78例OSAS患儿纳入OSAS组,另选取未接受过耳鼻喉科、正畸或语言治疗的78名健康体检儿童纳入健康对照组。2组儿童均接受耳鼻喉科评估和头影测量,且OSAS组患儿接受夜间多导睡眠描记(PSG)检查。结果面部头影测量结果显示,OSAS组面部前高度(N-Me)、面部前下高度(ANS-Me)均高于健康对照组,差异有统计学意义(P<0.05);OSAS组面部上前高度(N-ANS)、面部后部总高度(S-Go)与健康对照组比较,差异无统计学意义(P>0.05)。舌骨测量结果显示,OSAS组舌骨点至下颌平面的垂直距离(HyS)、舌骨体之最前上方至第三颈椎之最前下点的线性距离(C3-H)、舌骨最前点(Dh-H)、舌骨最前点至腭平面的垂直距离(HyMP)、舌骨最后点(Dv-H)均大于健康对照组,差异有统计学意义(P<0.05)。结论相较于健康儿童,OSAS患儿面部生长发育存在明显变化,表现为N-Me和ANS-Me增加,HyS、C3-H、HyMP、Dh-H、Dv-H增加。

跨学科视野下的批评延展与知识生产——“影游融合”研究综述

“影游融合”具有跨学科的研究特质,可以在视野延展与知识拓展的维度上增益影视批评良性发展。学术脉络上,这一问题牵扯到版权、技术、营销等多重因素,经历了“电影与游戏”“影游联动”“影游融合”的概念演变轨迹,形成了以陈旭光为主导,涉及学术合法性、新美学特征、跨界差异、产业发展、媒介结合体、接受主体等多方面的研究现状。在促进交叉研究的新文科理念下,重新梳理相关研究成果有助于发现与补足短板,为“接着讲”提供有益参照。

基于SoS核函数调制的超声图像伪影剔除方法

针对超声图像伪影严重的问题,提出了一种基于SoS核函数调制的超声图像伪影剔除方法,该方法能同时剔除由等声程线扩散、传感器拖尾现象和检测噪声产生的伪影.该方法利用SoS核函数对测得的超声回波信号进行调制,对调制后的信号等间隔低速率采样来获取离散序列值,再对离散序列进行离散傅里叶变换得到傅里叶系数序列,利用谱估计算法对回波信号参数进行估计,获取检测信号的特征参数,最后对回波信号进行自适应重构,计算声场得到超声图像.试验结果表明,聚焦和直探头对槽和通孔类缺陷的去伪影效果明显,与传统B扫图像相比,峰值信噪比分别达到了24.306、23.213、15.074和16.444 dB,结构相似度分别为0.931、0.932、0.746和0.773,表明该算法有效提高了缺陷图像的质量.