Mechanism of Aperture Blinding in Screening Wet and Fine Coal

The agglomeration of moist fine coal and the mechanism of aperture blinding in screening were analyzed. The theoretical analysis and a pilot test on that the elastic screen mesh can overcome the aperture blinding problem were presented.

Pay-based Screening Mechanism: Personnel Selection in the View of Economics Theory

Based on economic theories, the paper studies the personnel selection at the asymmetric job market using signaling and screening model. The authors hold the opinion that an organization can screen the candidates' signaling based on the self-selection principle by providing an appropriate compensation choice. A pay-based screening mechanism is proposed to help the organization drive away the nonqualified applicants and retain the excellent applicants.

Attention-relation network for mobile phone screen defect classification via a few samples

How to use a few defect samples to complete the defect classification is a key challenge in the production of mobile phone screens.An attention-relation network for the mobile phone screen defect classification is proposed in this paper.The architecture of the attention-relation network contains two modules:a feature extract module and a feature metric module.Different from other few-shot models,an attention mechanism is applied to metric learning in our model to measure the distance between features,so as to pay attention to the correlation between features and suppress unwanted information.Besides,we combine dilated convolution and skip connection to extract more feature information for follow-up processing.We validate attention-relation network on the mobile phone screen defect dataset.The experimental results show that the classification accuracy of the attentionrelation network is 0.9486 under the 5-way 1-shot training strategy and 0.9039 under the 5-way 5-shot setting.It achieves the excellent effect of classification for mobile phone screen defects and outperforms with dominant advantages.

Sentiment classification model for bullet screen based on self-attention mechanism

With the development of short video industry,video and bullet screen have become important ways to spread public opinions.Public attitudes can be timely obtained through emotional analysis on bullet screen,which can also reduce difficulties in management of online public opinions.A convolutional neural network model based on multi-head attention is proposed to solve the problem of how to effectively model relations among words and identify key words in emotion classification tasks with short text contents and lack of complete context information.Firstly,encode word positions so that order information of input sequences can be used by the model.Secondly,use a multi-head attention mechanism to obtain semantic expressions in different subspaces,effectively capture internal relevance and enhance dependent relationships among words,as well as highlight emotional weights of key emotional words.Then a dilated convolution is used to increase the receptive field and extract more features.On this basis,the above multi-attention mechanism is combined with a convolutional neural network to model and analyze the seven emotional categories of bullet screens.Testing from perspectives of model and dataset,experimental results can validate effectiveness of our approach.Finally,emotions of bullet screens are visualized to provide data supports for hot event controls and other fields.

Low-salinity-based enhanced oil recovery literature review and associated screening criteria

A thorough literature review is conducted that pertains to low-salinity-based enhanced oil recovery(EOR).This is meant to be a comprehensive review of all the refereed published papers,conference papers,master’s theses and other reports in this area.The review is specifically focused on establishing various relations/characteristics or"screening criteria"such as:(1)classification/grouping of clays that have shown or are amenable to low-salinity benefits;(2)clay types vs.range of residual oil saturations;(3)API gravity and down hole oil viscosity range that is amenable for low salinity;(4)salinity range for EOR benefits;(5)pore sizes,porosity,absolute permeability and wettability range for low-salinity EOR;(6)continuous low-salinity injection vs.slug-wise injection;(7)grouping of possible low-salinity mechanisms;(8)contradictions or similarities between laboratory experiments and field evidence;and(9)compositional variations in tested low-salinity waters.A proposed screening criterion for low-salinity waterflooding is introduced.It can be concluded that either one or more of these mechanisms,or a combination thereof,may be the case-specific mechanism,i.e.,depending on the particular oil–brine–rock(OBR)system rather than something that is"universal"or universally applicable.Therefore,every OBR system that is unique or specific ought to be individually investigated to determine the benefits(if any)of low-salinity water injection;however,the proposed screening criteria may help in narrowing down some of the dominant responsible mechanisms.Although this review primarily focuses on sandstones,given the prominence of carbonates containing^60%of the world’s oil reserves,a summary of possible mechanisms and screening criteria,pertaining to low-salinity waterflooding,for carbonates is also included.Finally,the enhancement of polymer flooding by using low-salinity water as a makeup water to further decrease the residual oil saturation is also discussed.

Electric-magnetic-force characteristics of rare earth barium copper oxide superconductor high-field coils based on screening effect and strain sensitivity

Rare earth barium copper oxide(REBCO)is the most researched and commercialized second-generation high-temperature superconducting material.Due to the anisotropic structure,strong deformation sensitivity,and central field errors caused by screening current effects,it is still a challenge for commercialization applications.In this study,the transversely isotropic constitutive relationship is selected as the mechanical model based on the structural characteristics of REBCO tapes,and suitable microelements are selected to equate the elastic constants using their average stress-strain relationships.Then,a two-dimensional axisymmetric model for coils wound by single-layer tapes is constructed to analyze the dependence of the electric-magnetic-force distribution in the tape on the strain.Finally,the anisotropic approximation of the homogenized bulk method is used to equate large-turn high-field coils,and the electric-magnetic-force distribution characteristics of the coils with/without screening effects and mechanical strain conditions are investigated,respectively.The results reveal that the mechanical strain has a weakening effect on the electromagnetic field distribution of superconducting tapes,but causes a significant enhancement in the force field distribution.In the presence of 0.5% mechanical strain,the maximum weakening of the peak value of the current density and the critical current density inside the high-field coil can reach about 8% and 13%,respectively,with a nearly 5 times increase in the peak stress.The screening current makes the current field distribution inside the coil improve by about 10 times.The screening current induced magnetic field can reach up to 0.8 T,making the relative error of the high-field coil center up to 7.8%.

Unified Treatment of Screening Coulomb and Anharmonic Oscillator Potentials in Arbitrary Dimensions

A mapping is obtained relating radial screened Coulomb systems with low screening parameters to radial anharmonic oscillators in N-dimensional space. Using the formalism of supersymmetric quantum mechanics, it is shown that exact solutions of these potentials exist when the parameters satisfy certain constraints.

Study on conglutination model for fine moist material during screening

All coal preparation in which fine coal is handled depends to some extent on the wettability of coal surface by water. The content of external water in fine moist material plays significant role on screening. This article probed into the causations why fine moist materials adhere to the screen deck on common vibrator in the process of screening. Although the wetting that results from interactions between the coal surface and water molecules that are determined by the composition of coal matrix (interrelated with coal rank) and heterogeneous constituents such as oxygen function groups, mineral impurities and pores have something to do with adhering, we found that the effect of wettability is not the key causation to agglomeration, in other words, water bridges among particles are the key causation to the fine moist materials’ adhesion. This paper also shows how the capillary adhesive forces forms and how to calculate and measure these forces.

高等教育筛选功能缺失的表征、归因与重塑

高等教育不仅具有传播知识、技能、思想与文化的社会化功能,还具有将不适合接受高等教育或某一专业的人才筛选出来的社会筛选功能。高等教育筛选机制的前提是获取教育文凭的学生要经历严格的筛选过程,教育文凭能够有效区分不同能力的学生。目前,我国高等教育在过程阶段和出口阶段并没有对学生的能力进行严格筛选和区分,最终导致不同能力的学生却获取了相同的文凭,劳动力市场出现了混同均衡现象。不仅如此,担负筛选功能任务的阶段还发生了“前移”和“后移”的状况:“前移”至基础教育阶段,导致教育竞争的不断提前,并且对优质教育资源的需求增加;“后移”至毕业生就业阶段,导致就业招聘“学历论”导向加剧,且产生了高校毕业生过度的教育现象,极大地浪费了高等教育资源。造成高等教育筛选功能缺失现象形成的原因是多方面的:传统思想的积淀与延续是价值前提,利益主体的理性选择是重要推力,制度安排与环境的不兼容是现实基础。破解此问题需要从以下几个方面入手:一是要革新认知观念,由“宽出”到“严出”;二是要转变价值取向,由“利益取向”到“责任取向”;三是要深化学分制改革,由“刻板教条”到“自由灵活”。

以“合宪性、涉宪性”为方法——从“连坐规定案”审查意见的方法逻辑切入

《全国人民代表大会常务委员会关于完善和加强备案审查制度的决定》第5条规定了涉宪性审查、合宪性审查的双审原理结构:一是通过涉宪性审查穷尽法律问题,通常情形下,合法性审查已实现有效审查,作为重要备位机制的合宪性审查不再启动;例外情形下,穷尽法律问题仍未能实现有效审查,则进而展开合宪性审查。二是通过合宪性审查援引宪法依据,当明确条款并依序援引,禁止向抽象的法规范逃逸。其中,在基本权利审查场域,具体的基本权利规范优先援引,进而依需要辅助援引或单独援引“概括性人权条款”。据此方法规范,“连坐规定案”审查意见在对“连”与“坐”涉宪性审查后,关于“连”的合宪性审查继续展开,所诉诸的“宪法第二章关于‘公民的基本权利和义务’规定的原则和精神”,包括优先援引的第38条人的尊严条款、第33条第2款平等权条款以及补强援引的第33条第3款“概括性人权条款”。

长江中下游崩岸险情智能感知预警与防治关键技术研究构想及成果展望

崩岸是长江中下游河道自然演变的常见形式,严重威胁防洪安全、航道畅通及沿江经济基础设施正常运行甚至是人民生命财产安全。三峡工程等水利水电工程建成运行引起长江中下游水沙情势显著改变,近年来,中下游河道持续冲刷、局部河势调整、崩岸频发,造成多方面不利影响。尽管以往已开展了相关研究并进行了治理,但由于影响因素众多,崩岸机理复杂,隐蔽性、突发性和随机性强,预警及治理难度依然很大。本文以“崩岸机理揭示—大范围筛查—介入式监测—多尺度预警—系统化防治”为总体思路开展研究,围绕流-固耦合作用下的崩岸机理与险情智能筛查、河道岸坡土体全要素实时感知及崩岸模拟预警技术、耦合河势控制措施的崩岸系统防治技术等关键科学技术问题,重点研究持续冲刷下河势变化与崩岸动态响应关系,研发多源信息融合的崩岸险情智能筛查技术、河道岸坡全要素一体化智能感知技术、多尺度河道崩岸预测与预警技术,以及耦合河势控制措施的崩岸系统防治技术,旨在揭示持续冲刷条件下长江中下游崩岸发生的驱动因素及内在机理,研发崩岸险情智能感知预警及防治关键技术,实现崩岸险情智能筛查、多要素监测、动态预警与系统防治。研究有望显著提高长江中下游河道崩岸发生的预见性和治理技术水平,促进崩岸从灾后抢护向灾前预防转变,为河道系统治理和水安全保障能力提升提供科技支撑。

扁平大空间船舶火灾烟气控制试验研究

为有效控制扁平大空间船舶火灾烟气蔓延,研究大尺度火灾过程中的油池质量损失速率、舱室温度分布、隔热效率和烟气控制效果。利用尺寸为30 m×24 m×2.3 m的模拟舱,在0.35、0.55和0.70 m等3种不同挡烟垂壁高度和机械通风条件下开展试验。结果表明:挡烟垂壁高度增加,油池质量损失速率峰值减小;挡烟垂壁高度对舱室上层烟气温度的影响比对下层气体温度的影响更明显,1.4 m以上空间温度峰值明显下降,而1.4 m以下空间温度峰值无明显变化。顶棚平均温度和隔热效率随挡烟垂壁高度增加而下降。随挡烟垂壁高度增加,火源区与非火源区同时控烟模式隔热效率从28.2%提升至50.8%,火源区单独控烟模式隔热效率从29.4%提升至54.7%。

基于筛分配比的超薄纤维板物理力学性能研究

为优化超薄纤维板的生产工艺,提高超薄纤维板生产效率与生产质量,通过筛分重组,探究纤维尺寸、配比对超薄纤维板的影响。结果表明:在相同的热压条件下,粗纤维的含量越高,超薄纤维板的吸水厚度膨胀率越高。单一尺寸纤维制备的超薄纤维板静曲强度、弹性模量随着纤维尺寸的增大而提高。不同尺寸混合纤维制备的超薄纤维板,当粗纤维、中长纤维和细纤维的比例为6:3:1时,静曲强度和弹性模量达到最大。

乡村治理监督的内化机制及其调适路径——以湖北省咸宁市通城县Z村为例

治理监督是促进乡村有效治理、推动乡村治理体系和治理能力现代化的重要保障。随着国家监督体系的完善,监督要素日益深入并内化到乡村治理过程中。从实践来看,治理监督的内化包括完善基层组织、凝聚治理共同体、形成规则共治等3个阶段。其中,组织继替的筛选机制、公共信任的整合机制、规则治理的约束机制是其得以内化的实践机制。当前,乡村治理监督内化面临组织持续继替难以保证、协商自治空间难以维持、主体共治意识普遍不强等现实困境。因此,需要引导后备人才返乡生活、释放基层治理协商空间以及提升基层组织动员能力,以保障“监督治村”的常态化与实效性。

基于CNN-LSTM-Attention的月生活需水预测研究

需水预测是进行水资源配置的重要部分,对于水资源合理开发利用和社会可持续发展有重要指导意义.本文以陕西省为研究区,结合大数据分析法,提出一种基于CNN-LSTM-Attention的月生活需水预测模型.首先,通过卷积神经网络(convolutional neural networks,CNN)提取数据动态变化特征,然后利用长短期记忆(long short-term memory,LSTM)网络对提取的特征进行学习训练,最后使用注意力(attention)机制分配LSTM隐含层不同权重,预测月生活需水量并对比实际数据.结果表明,CNN-LSTM-Attention模型的相对平均误差值和决定系数(R2)分别为2.54%、0.95,满足预测精度需求,相比于LSTM模型预测精度更高.进一步证明了模型预测的合理性,可为陕西省水资源规划提供指导.

外保护套对预充填筛管过流能力的影响研究

外保护套作为机械筛管的重要组成部件,对筛管过流能力的影响不可忽略。为此,以预充填筛管为例,通过一套小型可视化防砂模拟试验装置研究了外保护套对预充填筛管过流能力的影响规律。试验结果表明:随着外保护套过流面积的增加,预充填筛管的米采油指数呈指数增加;当外保护套上的冲缝槽宽度小于地层原始砂粒径中值的3倍时,砂粒通过冲缝槽时易发生架桥堵塞,导致筛管过流能力大幅度下降;当外保护套上的冲缝槽宽度大于等于地层原始砂粒径中值的3倍时,外保护套上的冲缝槽对地层砂通过基本没有影响,且有利于预充填筛管发挥其自解堵功能。所得结论可为预充填筛管外保护套的设计提供依据。

基于100 MeV强流质子回旋加速器生产放射性同位素的束流筛选装置

在进行放射性同位素生产实验时,有时需要100 MeV强流质子回旋加速器引出单圈束流来满足实验要求。目前100 MeV强流质子回旋加速器束流引出时存在严重圈重叠问题,因此需要设计一款束流筛选装置对引出束流品质进行改善以满足实验要求。该束流筛选装置具有基于100 MeV强流质子回旋加速器的框架结构与狭缝运动系统,以及基于PLC设计的控制系统控制步进电机并利用电子尺和按偏差的比例P、积分I和积分D(PID)控制的算法实现闭环控制。经过多次运行调试,机械装置的运动精度在±0.2 mm,且在加速器运行过程中可以实现对束流的筛选。

分子对接在筛选抗宫颈癌药物中的研究进展

宫颈癌是最常见的妇科恶性肿瘤之一,在淋巴结转移和远处转移的情况下,五年生存率显著下降,因此研发新型抗宫颈癌药物对于治疗宫颈癌有重大的意义。分子对接技术是计算机辅助药物设计技术中最常用的研究方法之一,在筛选药物有效成分、发现药物作用于肿瘤的靶点以及探索抗肿瘤药物的作用机制中被广泛应用。本文将分子对接技术在抗宫颈癌药物筛选、抗肿瘤靶标确定方面以及抗宫颈癌作用机制等方面作一综述,为筛选抗宫颈癌药物及新药研发提供更充分的理论依据。

辉长岩骨料全级配碾压混凝土力学特性研究

辉长岩坚硬致密,具有高强度、高弹模特性,但将辉长岩骨料应用于大型水电工程在国内外尚无先例,缺乏可借鉴的工程实践经验,且湿筛碾压混凝土试件的力学性能无法真实反映全级配碾压混凝土的力学特性。对辉长岩骨料最大粒径为80 mm的全级配碾压混凝土的力学特性演化规律开展了系统研究,包括抗压强度、劈拉强度、轴压性能、轴拉性能、抗剪性能等,对比分析了全级配碾压混凝土抗压、劈拉强度及其湿筛试件的尺寸效应,并将试验结果与国内典型工程所用碾压混凝土的力学性能发展规律进行对比分析,此外还建立了辉长岩骨料全级配碾压混凝土抗压强度、劈拉强度、轴压性能、轴拉性能等力学性能-养护龄期演化函数模型。结果表明:辉长岩骨料全级配碾压混凝土的抗压强度、劈拉强度、抗剪等力学性能随龄期的发展规律符合国内同类工程碾压混凝土力学性能发展的一般规律;C_(90)20W8F100辉长岩全级配碾压混凝土试件与其湿筛试件抗压强度平均尺寸效应系数为0.80、劈拉强度平均尺寸效应系数为0.66;相关力学性能演化模型相关性高(R^(2)=0.9643~0.9992)。可见辉长岩骨料用于大型水电工程碾压混凝土坝建设具有可行性。

大豆耐盐碱生理机制及种质筛选研究进展

我国盐碱地面积大、分布广,且次生盐碱化问题日益严峻,盐碱地面积的不断增加成为制约农业发展的重要因素,选育能够适应逆境的作物品种是发挥盐碱土地生产潜力最主要的途径。大豆属于中度耐盐植物,是世界第四大作物,也是我国重要的粮食、经济和饲料兼用作物,筛选培育优质耐盐碱大豆品种对合理利用盐碱地、促进我国农业可持续发展具有重要意义。本文从盐碱土的类型及对植物的危害、盐碱土对大豆生长的危害、大豆耐盐碱生理机制、耐盐碱大豆种质筛选4个方面对大豆耐盐碱性研究现状进行综述,以期为大豆耐盐碱新品种的选育提供理论基础和育种思路。