对用户开展精细化用电行为画像及分类,是电力企业精准掌握用户用电规律、提升服务水平和市场竞争力的关键因素之一.针对当前电力用户分类研究中用户用电行为画像结果片面、集成学习负荷分类研究中的基分类器冗余问题及负荷类别不平衡问题,提出一种基于用电行为数字特征画像的电力用户两阶段分类算法.第一阶段,提出一种结合谱聚类和集成强基分类器的用户日负荷曲线分类算法:首先,针对集成学习基分类器学习能力弱的不足,提出一种基于改进长短期记忆网络(long short-term memory,LSTM)的强基分类器;其次,针对基分类器冗余问题,提出一种基于最小正则化代理经验风险的优化选择集成策略;然后,提出一种基于密度的高斯过采样方法处理类别不平衡.第二阶段,基于负荷曲线分类结果,构建以日负荷模式发生概率为数字特征的用户用电行为画像,采用谱聚类算法对用户画像实施分类.最后,通过实测用户负荷数据验证了所提方法的有效性.

深度挖掘用户负荷规律并感知用电行为对于提升电网服务质量、改善用户用能体验具有重要意义.针对用户负荷中存在的数据缺失、类别不平衡问题以及分类模型性能缺陷,提出一种基于数据增强和双向深度残差时间卷积网络(temporal convolutional network,TCN)的电力用户负荷曲线分类方法.首先,提出考虑负荷数据全局分布特性的两阶段数据增强方法,第一阶段采用基于张量奇异值阈值算法的低秩张量补全方法补全缺失数据,第二阶段使用基于Wasserstein距离的生成对抗网络过采样少数类样本,解决类别不平衡问题.其次,构建融合双向时序特征的深度残差TCN分类模型,实现大规模用电曲线精准辨识.最后,通过选取公开时序分类基准数据集以及实测负荷数据集,验证了所提分类模型在收敛速度和分类精度上具有更好的性能,所提数据增强方法能有效提升模型分类效果.

本文讨论静磁球谐多极矩展开,包括静磁标势和静磁矢势的外部球谐多极矩展开.在磁矢势外部球谐多极矩分析中介绍了两种不同的方法,方法一基于磁标势外部球谐多极矩展开求惯用磁矢势外部球谐多极矩展开,方法二从电流对远源场点磁矢势场贡献出发借助德拜势直接求得静磁矢势外部球谐多极矩展开的惯用表示.

19世纪初英国殖民者在英属印度推广牛痘疫苗,本以为是一场进步运动,不想这却与本土社会文化之间形成了旷日持久的冲突与妥协.随着牛痘疫苗的引入,印度民众的态度呈现出多样性,既有因文化差异和现实问题而导致的抵制,也有本土精英的改良建议和强制主张,以及在天花肆虐的特殊时刻印度民众的普遍接受.英属印度政府以促进牛痘疫苗的推广为目标,一方面采取强制手段取缔人痘接种,强行实施牛痘接种,另一方面也注重通过缓和与印度传统文化的紧张关系以及解决牛痘接种中的现实问题,对疫苗政策做出一定的调整.到19世纪末20世纪初,牛痘接种已取得很大进展,有效降低了天花死亡率.总之,19世纪牛痘疫苗在英属印度的推广是探索殖民时期印度社会历史变迁的重要切入点.

In modern power systems, analyzing the behaviors of the end users can help to improve the system’s security, stability, and economy. Load classification provides an efficient way to implement awareness of the user’s behaviors. However, due to the development of data collection, transmission, and storage technologies, the volumes of the load data keep increasing. Meanwhile, the structure and knowledge hidden in the data become ever more complicated. Therefore, the parallelized ensemble learning method has been widely employed in recent load classification research. Although the positive performance of ensemble learning has been proven, two critical issues remain: class imbalance and base classifier redundancy. These issues raise challenges of improving the classification accuracy and saving computational resources. Therefore, to solve the issues, this article presents an improved selective ensemble learning approach to enable load classification considering base classifier redundancy and class imbalance. First, a Gaussian SMOTE based on density clustering (GSDC) is introduced to handle the class imbalance, which aims to achieve higher classification accuracy. Second, the classifier pruning strategy and the optimization strategy of the ensemble learning are further introduced to handle the base classifier redundancy. The experimental results indicate that when combined with the popular classifiers, the presented approach shows effectiveness for serving the load classification tasks.

本文以媒质所受电磁场作用力为纽带,分别从极化电荷分布与电极化强度出发推导媒质所受电场作用力,从磁化电流与磁化强度出发推导媒介所受磁场作用力,不仅可以得到电极化强度与极化电荷体密度的关系以及磁化强度与磁化电流体密度的关系,还可直接得到孤立媒质边界处极化电荷面密度与电极化强度的关系以及磁化电流面密度与磁化强度的关系,故这种方法具有很强的通用性且更易理解.

2019年12月,湖北武汉暴发不明原因肺炎.2020年1月7日,我国首次证实病原体为一种全新的冠状病毒,并完成基因组全长测序[1].2020年2月11日,国际病毒分类委员会将此病毒命名为严重急性呼吸综合征冠状病毒2 (severe acute respiratory syndrome coronavirus 2,SARS-CoV-2);同日,世界卫生组织将此病毒引发的疾病命名为2019冠状病毒病(coronavirus disease 2019,COVID-19).

对称是现代物理学中位于基础地位的重要概念.电动力学教与学中应用对称开展分析,不仅仅有助具体问题解析,更有助于深化对电磁场宏观性质的认识和理解.电动力学研究对象——宏观电磁场不具有实物物质形态,故其对称性并不是显而易见的.本文从麦克斯韦方程组出发,采用非相对论形式的语言介绍宏观电磁场具有的普遍对称性,分析居于经典宏观电磁场理论基础地位的规范不变性是如何引起宏观电磁场对偶性破缺,并在此基础上探讨电动力学教与学中易混淆的两个概念——磁荷与磁单极子.

随着连接器配套领域产品的飞速发展,电子连接器正向着轻型化、小型化、高频信号、高Pin数、高精度和标准化方向发展.与此同时,对电子连接器的质量要求也日益提高.传统的人工抽检方法已经不能满足要求.基于机器视觉的检测技术对实现连接器高效、自动、精确的自动检测极为适用.本系统采用条形组合光源和同轴光配合,从4个方向上低角度照射连接器表面,能很好地突出表面缺陷及测量针脚尺寸.在软件算法方面,针对连接器型号多样化带来的定位问题,提出了小范围匹配找定位的方法.整体系统实现了对连接器外观质量的高速实时在线检测.

Objective:To evaluate the validity and repeatability of GRE cine sequence when it was used to evaluate the heart function of rhesus monkey,and to provide an accurate and optimal cardiac function assessment strategy for the study of rhesus monkey cardiac disease models.Methods:Eight healthy rhesus monkeys underwent conventional echocardiography and CMR GRE cine sequence scanning to assess cardiac function and got left ventricular end-diastolic volume(EDV),left ventricular end-systolic volume(ESV),stroke volume(SV),ejection fraction(EF),cardiac output(CO),left ventricular end-diastolic mass (Myo Mass(Diast)) and left ventricular end-systolic mass(Myo Mass(Syst)).The repeatability of GRE was evaluated by the testretest analysis.The validity of the GRE was evaluated by criterion-related validity by comparing the results of ultrasound and GRE.Results:The results of test-retest analysis showed that correlation coefficient(ICC) values of all function parameters were within 0.75～0.97,the P value was less than 0.01,and the results of repeated evaluation were better.The results of criterionrelated validity showed that except for CO,the Pearson correlation coefficient (r) values of the other function parameters were 0.80～0.92,and the difference was statistically significant.It was found that EF,CO and Myo Mass (Diast) acquired by GRE were smaller than those measured by ultrasound,and the difference was statistically significant.Conclusion:There are good validity and repeatability using the CMR GRE cine sequence to evaluate the cardiac function of normal rhesus monkey.

通过滑坡涌浪模型试验,运用高速摄像机记录滑坡入水形成涌浪的过程,并采用多功能监测系统测量滑坡涌浪形成后沿程传播的水位变化过程线,揭示了滑坡涌浪的初始运动形态特征和衰减变化规律.由于滑坡体的高速入水,水体的形态从冲溅形态发展到前涌形态再到后溃形态,伴随着冲溅形态水体的大片落下、前涌形态水体的前涌和后溃形态水体的向后溃倒,最终形成初始形态的涌浪.创新性地引入涌浪初始形态Froude数,并据其数值范围将涌浪的初始形态分为三种形态:常规涌浪、推移涌浪、跃冲涌浪.在运动的过程中,常规涌浪衰减为波形较稳定的波;推移涌浪将慢慢地衰减为常规涌浪;跃冲涌浪先衰减为推移涌浪再衰减为常规涌浪.

通过胶黏合法建立人胃癌裸鼠原位移植模型,并使用7T核磁共振成像(7T Mm)动态检测原位肿瘤.将对数生长期人胃低分化腺癌SGC-7901细胞制成细胞悬液注射于裸鼠右腋皮下,建立皮下移植模型;以皮下移植瘤块为材料,采用胶黏合法建立原位移植模型.造模约20 d后,裸鼠进行7T MRI扫描,并对胃部组织进行组织病理学检查.3只裸鼠中2只胃部可见肿瘤疑似物,组织病理学检查验证该疑似物为肿瘤,成瘤率达66.7％.实验结果表明,7T MRI对原位肿瘤可进行无创、动态的活体检测,且无辐射伤害.MRI检测有望用于临床前胃癌药物的研发以及临床胃癌的诊断.

During the teaching practice of the thermology course ,we find that some students tend to think of microscopic atoms in the classical Newtonian model .Thus ,when we discuss the degrees of freedom of gas molecules ,the students who think actively will get confused with the concepts of atom spin and the rotational degree of freedom .For this reason ,the spin and rotational degrees of freedom of single atom are discussed in this paper .The difference be‐tween the physical picture of quantum mechanical spin and the physical picture of classical New tonian mechanical rotation is explored .We point out the spin of microscopic particles is an intrinsic property ,which has no corresponding concept in classical physics .And we conclude that the simplified model that assumes the atom as a particle is appropriate for entry‐level un‐dergraduates in the sense that it can assist them to understand the basic concept and physical picture of atomic degrees of freedom .

Urokinase plasminogen activator receptor (uPAR) is a membrane protein which is attached to the cellular external membrane. The uPAR expression can be observed both in tumor cells and in tumor-associated stromal cells. Thus, in the present study, the human amino-terminal fragment (hATF), as a targeting element to uPAR, is used to conjugate to the surface of superparamagnetic iron nanoparticle (SPIO). Flowcytometry was used to examine the uPAR expression in different tumor cell lines. The specificity of hATF-SPIO was verified by Prussian blue stain and cell phantom test. The imaging properties of hATF-SPIO were confirmed in vivo magnetic resonance imaging (MRI) of uPAR-elevated colon tumor. Finally, the distribution of hATF-SPIO in tumor tissue was confirmed by pathological staining. Results showed that the three cells in which we screened, presented different expression characteristics, i. e., Hela cells strongly expressed uPAR, HT29 cells moderately expressed uPAR, but Lovo cells didn't express uPAR. In vitro, after incubating with Hela cells, hATF-SPIO could specifically combined to and be subsequently internalized by uPAR positive cells, which could be observed via Prussian blue staining. Meanwhile T2WI signal intensity of Hela cells, after incubation with targeted probe, significantly decreased, and otherwise no obvious changes in Lovo cells both by Prussian blue staining and MRI scans. In vivo, hATF-SPIO could be systematically delivered to HT29 xenograft and accumulated in the tumor tissue which was confirmed by Prussian Blue stain compared to Lovo xenografts. Twenty-four hours after injection of targeting probe, the signal intensity of HT29 xenografts was lower than Lovo ones which was statistically significant. This targeting nanoparticles enabled not only in vitro specifically combining to uPAR positive cells but also in vivo imaging of uPAR moderately elevated colon cancer lesions.

It was discovered that in flume experiment, under certain conditions, the dropping flow forms napped flow, skimming flow and periodic oscillation flow. Based on the numerical simulation,flume experi?ment and theoretical analysis, this paper focuses on studying the energy dissipation mechanism,flow evolu?tion characteristics and generating mechanism of periodic oscillatory flow. The results show that the flow pat?tern of periodic oscillation flow presents a similar wave of broken and hydraulic jump. The vertical drop pool is divided into recirculation region,level of impact zone,the vertical impact zone,oscillation and bro?ken zone and the tail vortex zone. Since fluid inertia and the reflection effect of structure disturb the origi?nal free surface,the periodic oscillation flow forms under the wave-mean vortex interaction.

In 1937, Von Neumann [1] established the famous coincidence theorem. Since then, the coincidence theorem was generalized in many directions. Browder [2] first proved some basic coincidence theorems for a pair of set-valued mappings in compact setting of topological vector spaces and gave some applications to minimax inequalities and variational inequalities. Recently, Ding [3] established some new coincidence theorems for a better admissible mapping on G-convex spaces by using the technique of a continuous partition of unity. In this paper, we will generalize these coincidence theorems on FC-spaces without convexity structure.

近年来,随着超声技术在医疗领域的广泛应用及微泡对比剂研制的进展,超声联合微泡技术作为一种安全、高效、操作简单,且具有一定靶向性的无创治疗手段,在高强度聚焦超声(HIFU)、药物传递、基因治疗、超声溶栓术、肿瘤治疗方面显示了巨大的应用潜力。就超声空化效应的治疗机制及应用予以综述。

介绍并分析了2009年华夏高等护理教育联盟"灾害护理概论"暑期课程的总体设计思路、课程内容、师资安排与教学方法、课程评价等,以期为国内灾害护理课程设置提供参考.

In this paper,an intelligent human-machine interface of laser cutting machine is introduced based on Atmel 89C51RC.It employes keybord and LCD as I/O equipment and RS 232 for communication,the software followed the thinking of modular design.Practice shows that the interface is simple,easy to operate,work stable and reliable.

本文针对CO2激光电源在工业现场的损坏现象,在CO2激光电源的整流滤波电路上进行浪涌防护实验,并分析了浪涌抑制器件的选择,确定了CO2激光电源的浪涌防护措施,实验验证了该措施有效、可行.