Improvement for design of beam structures in large vibrating screen considering bending and random vibration

Demand for large vibrating screen is huge in the mineral processing industry. As bending and random vibration are not considered in a traditional design method for beam structures of a large vibrating screen, fatigue damage occurs frequently to affect the screening performance. This work aims to conduct a systematic mechanics analysis of the beam structures and improve the design method. Total motion of a beam structure in screening process can be decomposed into the traditional followed rigid translation(FRT), bending vibration(BV) and axial linear-distributed random rigid translation(ALRRT) excited by the side-plates. When treated as a generalized single-degree-of-freedom(SDOF) elastic system analytically, the BV can be solved by the Rayleigh's method. Stochastic analysis for random process is conducted for the detailed ALRRT calculation. Expressions for the mechanics property, namely, the shearing force and bending-moment with respect to BV and ALRRT, are derived, respectively. Experimental and numerical investigations demonstrate that the largest BV exists at the beam center and can be nearly ignored in comparison with the FRT during a simplified engineering design. With the BV and FRT considered, the mechanics property accords well with the practical situation with the maximum error of 6.33%, which is less than that obtained by traditional method.

Static-deformation based fault diagnosis for damping spring of large vibrating screen

Based on the statics theory, a novel and feasible twice-suspended-mass method(TSMM) was proposed to deal with the seldom-studied issue of fault diagnosis for damping springs of large vibrating screen(LVS). With the static balance characteristic of the screen body/surface as well as the deformation compatibility relation of springs considered, static model of the screen surface under a certain load was established to calculate compression deformation of each spring. Accuracy of the model was validated by both an experiment based on the suspended mass method and the properties of the 3D deformation space in a numerical simulation. Furthermore, by adopting the Taylor formula and the control variate method, quantitative relationship between the change of damping spring deformation and the change of spring stiffness, defined as the deformation sensitive coefficient(DSC), was derived mathematically, from which principle of the TSMM for spring fault diagnosis is clarified. In the end, an experiment was carried out and results show that the TSMM is applicable for diagnosing the fault of single spring in a LVS.

Correlation Analysis between Mean Corpuscular Hemoglobin and Mean Corpuscular Volume for Thalassemia Screening in Large Population

Correlation analysis between the hematological parameters mean corpuscular hemoglobin (MCH) and mean corpuscular volume (MCV) for thalassemia screening in large population was discussed. A total of 4920 peripheral blood samples of reproductive age persons were collected from Guangdong province of China. The hematological parameters MCH and MCV values of samples were first measured, and then the DNA analyses for thalassemia were conducted. All samples were composed by 4463 non-thalassemia and 457 thalassemia, and among 457 thalassemia samples, 311 were α-thalassemia, 133 were β-thalassemia, and 13 were α & β-thalassemia. In accordance with non-thalassemia, thalassemia, α-thalassemia, β-thalassemia, α & β-thalassemia and the entire group itself, a total of six sample groups were divided. The corresponding correlation coefficients between the measured MCH and MCV values for the six sample groups were 0.880, 0.968, 0.966, 0.962, 0.980 and 0.965 respectively. For the thalassemia carriers, highly significant correlation between MCH and MCV were observed. The fitting equations between MCH and MCV values were also obtained. The results indicated that the feasibility for thalassemia screening using MCV or MCH independently as parameter, and provided suitable strategy to select parameters and models for thalassemia screening in large population.

Integrated Management of Large Screen Communication Strategy for Electric Vehicles

The intelligent product of traditional fuel vehicles in electric vehicle region is the large screen of central control panel, which is the subversive innovative design of electric vehicles and the intelligent symbol under the Internet innovative thinking. Through the specific analysis of large screen innovative design, target customers, communication channel and communication effect of electric vehicle products, the comprehensive management of large screen communication of electric vehicles can be realized.

Characteristics analysis of a novel centralized-driving flip-flow screen

During screening operation, blinding or clogging of screen perforations generally occurs to reduce the sieving capacity and efficiency. Recently, the flip-flow screening has been widely recognized as a feasible method to deal with the problem. In this paper, a novel centralized-driving flip-flow screen(CFS) was developed for the separation of fine and moist coal, and the key structures, namely, a centralized-driving mechanism and a quasi-circle beam mounted with the mat were designed for high reliability and stability. By means of a test on an experimental prototype, the effect of some factors, i.e., initial stretch and hardness of the polyurethane panel, respectively, and the rotation speed of the driving motor on the kinematic characteristic of the screen surface was investigated. Results show that without an initial stretch, the sieve mat generates the largest vibratory amplitude while the slacker the sieve mat initially is, the smaller amplitude it will accomplish. And an increase in the rotation speed could cause a rise in the vibratory amplitude. Unlike the two factors, the hardness does not have a definite effect on the kinematic performance, on which a further study is required. Finally, screening processing on a laboratory prototype was conducted to draw the conclusion that the developed CFS also has a high sieving efficiency for the fine and moist coal.

Integral Optimization of Systematic Parameters of Flip-Flow Screens

The synthetic index K s for evaluating flip-flow screens is proposed and systematically optimized in view of the whole system. A series of optimized values of relevant parameters are found and then compared with those of the current industrial specifications. The results show that the optimized value K s approaches the one of those famous flip-flow screens in the world. Some new findings on geometric and kinematics parameters are useful for improving the flip-flow screens with a low K s value, which is helpful in developing clean coal technology.

五种院前卒中筛查量表对院内急性大血管闭塞性缺血性卒中的预测价值

目的探讨并分析5种院前卒中筛查量表对院内急性大血管闭塞性缺血性卒中的预测价值。方法回顾性纳入2015年1月—2022年12月,因非卒中相关疾病收入东台市人民医院并在住院期间因疑似卒中症状激活院内卒中绿色通道的所有患者。采用ROC曲线评估筛查量表对院内急性大血管闭塞性缺血性卒中的预测价值。5种筛查量表分别为卒中现场评估和分类转运量表(field assessment stroke triage for emergency destination,FAST-ED)、快速动脉闭塞评估量表(rapid arterial occlusion evaluation,RACE)、洛杉矶运动量表(Los Angeles motor scale,LAMS)、辛辛那提院前卒中严重程度量表(Cincinnati prehospital stroke severity scale,CPSSS)和院前急性卒中严重程度量表(prehospital acute stroke severity scale,PASS)。结果本研究共纳入174例患者,其中54例(31.0%)患者诊断为急性大血管闭塞性缺血性卒中。RACE(AUC 0.888,95%CI 0.849~0.928)和LAMS(AUC 0.859,95%CI 0.812~0.905)对急性大血管闭塞性缺血性卒中的预测效能最高,其次是FAST-ED(AUC 0.820,95%CI 0.768~0.872)、CPSSS(AUC 0.810,95%CI 0.756~0.863)和PASS(AUC 0.786,95%CI 0.727~0.844),三者之间差异无统计学意义。结论院前卒中筛查量表在预测院内急性大血管闭塞性缺血性卒中方面均显示出良好的预测能力,其中RACE和LAMS的预测效能最高。

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%。

Complex granular flows of sticky-wet material on flip-flow screens:Calibration of discrete element simulations

Discrete element method(DEM)is an effective approach for studying the screening process of flip-flow screens.However,there have been few studies focusing on the thick layer of sticky-wet particles on flip-flow screens.To achieve accurate simulations of the thick layer of sticky-wet particles on a flip-flow screen,firstly,the movement law of particle flow was studied,and a multi-regime combination cali-bration method based on characteristics of particle flow regimes was proposed.Based on the Plackett-Burman experiment,the curse of dimensionality caused by multi-state and multi-contact parameters was overcome.Subsequently,the lifting cylinder,rotating drum,and trampoline tests were carried out to obtain macroscopic reference values under various granular flow regimes.The calibration results were then determined using the response surface method and climbing algorithm.Finally,the calibration results were tested at both macroscopic and mesoscopic scales and compared with a commonly used calibration method.The results demonstrate that the calibration method,which considers the multi-state characteristics,improves simulation accuracy by 2%-10%and reduces the simulation error to less than 10%,thus meeting the requirements for engineering optimization of flip-flow screens.

不同茶树品种黄大茶降糖降脂功效比较分析

黄大茶是我国独有的一种茶类,以一芽四叶茶树鲜叶为原料,具有独特的干茶黄、汤色黄、叶底黄的“三黄”品质。黄大茶健康功效显著,具有降低血糖和血脂的作用,但以不同茶树品种制成的黄大茶,其降糖、降脂功效是否存在差异尚不清楚。为此,选取了13个不同茶树品种,按照黄大茶标准工艺制成干茶,通过测定其水提物对α-葡萄糖苷酶活性抑制率和对3T3-L1前脂肪细胞分化的影响,比较其体外降糖、降脂功效。结果表明,降糖效果最佳的茶树品种是黄金桂,α-葡萄糖苷酶IC50值为185.17μg/mL。降脂效果最好的茶树品种是柿大茶1号,茶汤处理后的3T3-L1前脂肪细胞中总胆固醇含量较对照组下降78.8个百分点,甘油三酯含量较对照组下降93.5个百分点。进一步对茶样进行生化成分含量测定与多元统计分析表明,皖茶91茶多糖含量最高,为5.59%,而茶农98茶多糖含量仅为3.38%。PCA分析结果表明,金鸡种和柿大茶1号在生化成分含量上与其他品种存在显著差异,其中总儿茶素为主要贡献物。相关性分析结果表明,茶多酚和茶多糖可能是影响不同茶树品种黄大茶降糖功效的主要活性物质,而总儿茶素和茶多糖则是影响黄大茶降脂功效的物质。综上所述,本研究比较分析了不同茶树品种黄大茶的降糖降脂功效和主要生化成分含量,将为以健康为导向的黄大茶品种筛选提供理论依据。

曲轴连杆式大型弛张筛关键部件动态特性

弛张筛作为选煤厂原煤干法深度筛分的关键装备,尤其曲轴连杆式弛张筛稳定性较好,在大型动力煤选煤厂得到广泛应用。曲轴连杆机构为该大型弛张筛的核心关键部件,其可靠性对筛分效果与后续分选环节均有重要影响。基于此,采用有限元仿真计算,聚焦曲轴连杆机构的动态特性,围绕哈尔乌素大型动力煤选煤厂大型弛张筛,构建曲轴连杆结构有限元模型并进行模态分析,进而基于模态叠加法进行简谐载荷作用下的谐响应分析,最后通过边界条件模拟其在筛机运行下的运动状态,对其进行了动力学分析。结果表明,其固有频率均远大于系统工作时的激振频率,曲轴连杆结构无共振风险;工作状态下曲轴连杆产生的应力集中在曲轴表面以及连杆的轴承处,最大应变为1.10×10^(-4),满足设计要求;同时,确定了连杆与曲轴间的机械碰撞是结构产生材料变形的主要原因。本研究结果为大型曲轴连杆式弛张筛的选型设计、结构优化以及工程实践提供了理论与技术参考。

大型振动筛运行状态在线监测系统研究与应用

目前振动筛运行状态主要依靠人工经验判断,现有在线监测方法因测量精度低,难以满足大型振动筛的智能化发展需求。为此,开发了振动筛运行状态在线监测系统,对该系统的构成与主要功能进行了概述;针对传统单轴或普通三轴单方向振动传感器准确性差的技术难题,建立了振动筛虚拟空间三维坐标系,利用运动矢量合成算法重构了筛机监测位点的实际振动方向角与振动强度,克服了传感器安装精度和现场工况条件对结果的影响,实现了筛机振动数据的精准测量;根据温度传感器实时数据获取轴承温升曲线,实现了温度数据的精准感知;通过对异常数据的分析,基于支持向量机建立了振动筛运行异常与预警模型。现场应用表明,在线监测系统实现了振动筛运行状态数字化判识与早期故障预警,显著降低了筛分装备故障率,保障设备高效稳定运行。

大尺寸插头PCB加工研究

随着各行业对显示屏需求的不断增加,显示屏越来越需要满足多元化设计要求。印制插头作为印制电路板(PCB)对位连接网络的必需端口,具有一定特殊性,与其连接的主板需要精密对位、高度重合,这就要求插头的涨缩尺寸保持稳定,厚度均匀性须一致。从覆铜板(CCL)及PCB过程管控入手,对显示屏用大尺寸插头PCB加工案例进行验证总结,为该类产品的加工提供一套解决方案。

基于Echarts的跨平台教学资源数字化展现解决方案

教学资源数字化是未来教育发展的重要趋势之一,它将为教育带来更多的机遇和挑战。文章提出一种基于Echarts的跨平台教学资源数字化展现解决方案。通过教学资源微信小程序、超星学习通和看数大屏的融合,满足了学生、教师以及管理人员不同角色的数字化需求。解决方案能够辅助教育决策,提供更高效和规范的管理方式,提高教学效果和教学质量。

大型炼焦煤选煤厂深度筛分技术研究

当前的选煤厂深度筛分一般设定为单向流程,筛分范围受到限制,导致筛分效率下降,为此提出对大型炼焦煤选煤厂深度筛分技术的设计与验证研究。综合实际的筛分需求及标准,设置分级筛分粒度标准,进行筛上筛下标定划归,采用多单组合处理的形式,在合理的范围之内,最大程度扩大筛分范围,制定多单元组合深度分筛流程,采用二次张拉弹性侧筛实现深度筛分处理。测试结果表明:经过三个阶段的测定,最终使得A选煤厂深度筛选的效率得到了极大地提升,可以达到60%以上,其筛选精度也得到了很大的提升,可以达到80%以上,说明该项筛分技术以及结构的实际应用效果更佳,筛分速度较快,误差可控,具有实际的应用价值。

穿屏互动技术在广电节目制作中的应用实践

本文介绍了在晚会节目中采用的穿屏互动技术,分析了业务需求,介绍了技术系统实践,重点探讨了该技术的创新应用以及大小屏融合的难点与挑战。

乡村数字可视化大屏的界面装饰元素创设

数字大屏旨在以可视化的方式传达数据信息和指标业务,因此大屏的界面设计显得至关重要。为了探索可视化大屏界面装饰元素的创设,以数字乡村可视化大屏为例,基于一定的图形图像处理技术和设计原则规范,从设计师的视角制定视觉风格、构建创设思路、设计装饰元素,最终实现装饰元素的整合和视觉效果的展示。

大屏幕技术在电视演播室中的互动性与实时性研究

探讨在电视演播室中提升大屏幕技术互动性与实时性的策略。通过利用人工智能(Artificial Intelligence,AI)驱动的智能互动、引入多感官互动技术、采用5G/6G通信技术、实施计算密集型任务的云端处理、构建基于物联网的实时互动系统以及探索新的互动形式和界面等方法,电视演播室可以实现更高效、更自然的节目互动,并提供近乎实时的观众体验。这些创新技术为电视节目制作与传播带来了新的机遇和挑战。

大型LED屏幕散热效率的模拟分析

大型LED屏幕作为时下流行的宣传工具,被广泛运用于商业或民用建筑中。本文针对浙江省金华市某居民楼建筑的大型LED屏幕,选取夏季空气调节室外计算干球温度和夏季极端天气情况下的气候状况,分析屏幕散热情况、热量排除及局部热堆积,给出空间内温度场分布情况和热量排出状况。结果表明,不同角度外界温度变化对屏后温度影响变化不大,而设置风机的数量增加能有效提升屏幕散热效果。本文同时依据以上结论,对具体施工提出建议,为相关工程项目提供参考。

大数据可视化分析助力企业智能物资采购全流程

随着数智油田的高速发展和建设,企业面对物资采购业务的不断发展和数据的不断增加,如何高效且准确地利用大数据分析技术对企业物资采购进行智能化分析,推进整体业务信息化发展、智能化应用,成为一个重要的研究课题。本文以帆软FineBI工具和可视化大屏为基础,深入探讨利用大数据分析技术实现企业物资采购的数据可视化、智能化应用。