中国石化开发出聚乙烯用改性催化剂及其制备方法

中国石油化工股份有限公司(简称中国石化)开发出一种聚乙烯用改性催化剂及其制备方法。该催化剂包括主催化剂和改性剂,两者质量比为100.0∶(0.1~30.0)。主催化剂为Ziegler-Natta催化剂、茂金属催化剂、后过渡金属催化剂、FI催化剂、铬基催化剂中的一种,改性剂为硅氧烷、苯乙烯基聚合物中的至少一种。该方法通过将改性剂引入主催化剂中,改变了主催化剂原有活性位点的分布和催化特性,进而可以改变聚乙烯活性链的生长和结晶行为,提高了聚乙烯的相对分子质量分布。

Vibration analysis of nano-structure multilayered graphene sheets using modified strain gradient theory

In this paper, for the first time, the modified strain gradient theory is used as a new size-dependent Kirchhoff micro-plate model to study the effect of interlayer van der Waals （vdW） force for the vibration analysis of multilayered graphene sheets （MLGSs）. The model contains three material length scale parameters, which may effectively capture the size effect. The model can also degenerate into the modified couple stress plate model or the classical plate model, if two or all of the material length scale parameters are taken to be zero. After obtaining the governing equations based on modified strain gradient theory via principle of minimum potential energy, as only infinitesimal vibration is considered, the net pressure due to the vdW interaction is assumed to be linearly proportional to the deflection between two layers. To solve the goveming equation subjected to the boundary conditions, the Fourier series is assumed for w = w（x, y）. To show the accuracy of the formulations, present results in specific cases are compared with available results in literature and a good agreement can be seen. The results indicate that the present model can predict prominent natural frequency with the reduction of structural size, especially when the plate thickness is on the same order of the material length scale parameter.

基于OBE理念的英语专业口语课程混合式教学改革探析

OBE即成果导向教育,是一种以学习成果为导向的教育理念。针对目前英语专业口语课程教学中存在的问题,在OBE理念指导下,以学生为中心,以“口语产出”为导向,依托Fi F口语训练系统,进行英语专业口语课程线上线下混合式教学改革,确保学生达成课程目标,提升英语口语能力和英语交际能力,为未来职业的成功打下良好基础。

基于折射率数据的玻璃物证比对检验似然比模型建立及评估

玻璃是常见微量物证,目前国内微量物证检验报告通常只列出检验数据或定性给出比对检验结论,无法量化表达物证比对鉴定结论。似然比证据价值评价方法在全世界被广泛接受,但在中国,针对玻璃物证的定量价值评价方法还未建立,给检察官和法官准确利用玻璃物证带来困难。为提升玻璃物证的证据价值,本文拟建立量化比对检验结论的似然比方法模型并进行评估。基于四大类150个玻璃样品共750个折射率的检验数据,采用高斯核密度估计方法建立似然比(LR)模型,采用直方图和两类错误率对该模型进行评估。通过建立的似然比模型计算得出同源样品间的LR值在6.58~204500范围内,不同源的样品间的LR值在0~0.68范围内,在150个样品的自身比对中,仅有一个样品自身比对的LR<1,错误排除率为0.67%;对150个不同来源玻璃样品进行两两比对,在C^(2)_(150)=11175对比对中,有173对LR>1,错误接纳率为1.55%,两个错误率均较低,在可接受范围内。基于高斯核密度估计建立的似然比模型能够对基于玻璃折射率数据的样品比对给出满意的比对结果,可为法庭提供玻璃样品比对的量化评估值。

Assessment of China’s forest fi re occurrence with deep learning, geographic information and multisource data

Considerable economic losses and ecological damage can be caused by forest fi res,and compared to suppression,prevention is a much smarter strategy.Accordingly,this study focuses on developing a novel framework to assess forest fi re risks and policy decisions on forest fi re management in China.This framework integrated deep learning algorithms,geographic information,and multisource data.Compared to conventional approaches,our framework featured timesaving,easy implementation,and importantly,the use of deep learning that vividly integrates various factors from the environment and human activities.Information on 96,594 forest fi re points from 2001 to 2019 was collected on Moderate Resolution Imaging Spectroradiometer(MODIS)fi re hotspots from 2001 to 2019 from NASA’s Fire Information Resource Management System.The information was classifi ed into factors such as topography,climate,vegetation,and society.The prediction of forest fi re risk was generated using a fully connected network model,and spatial autocorrelation used to analyze the spatial aggregation correlation of active fi re hotspots in the whole area of China.The results show that high accuracy prediction of fi re risks was achieved(accuracy 87.4%,positive predictive value 87.1%,sensitivity 88.9%,area under curve(AUC)94.1%).Based on this,it was found that Chinese forest fi re risk shows signifi cant autocorrelation and agglomeration both in seasons and regions.For example,forest fi re risk usually raises dramatically in spring and winter,and decreases in autumn and summer.Compared to the national average,Yunnan Province,Guangdong Province,and the Greater Hinggan Mountains region of Heilongjiang Province have higher fi re risks.In contrast,a large region in central China has been recognized as having a long-term,low risk of forest fi res.All forest risks in each region were recorded into the database and could contribute to the forest fi re prevention.The successful assessment of forest fi re risks in this study provides a comprehensive knowledge of fi re risks in China over the last 20 years.Deep learning showed its advantage in integrating multiple factors in predicting forest fi re risks.This technical framework is expected to be a feasible evaluation tool for the occurrence of forest fi res in China.

Geospatial characteristics of fire occurrences in southern hemispheric Africa and Madagascar during 2001-2020

For this study of long-term spatial patterns and trends of active fires in southern hemispheric Africa and on Madagascar from 2001 to 2020,active fire data from the MODIS FIRMS global fire data products were analyzed.The annual center of fire concentration tended to migrate toward the preserved rainforests and nature conservation areas in the Congo Basin and the mountain forests on the northeastern coast of Madagascar.Fire frequency varied seasonally at both study areas.We used geo statistical analysis techniques,such as measures of dispersion and emerging hot spot analysis,to reveal long-term trends in spatial patterns of fire events.In southern hemispheric Africa,the observed active fires tended to drift northward toward the Zambia-DRC border in the Congo basin.This northward migration progressed toward humid rainforests,which were better suited to sustaining repeated fire events.On Madagascar,the observed active fires tended to migrate toward the east coast in protected mountain forests.The spatial patterns of long-term trends showed a concentration of fires in the tropical regions of southern hemispheric Africa.Moreover,smaller clusters of new hot spots were located over eastern South Africa,overlapping with undifferentiated woodlands.On Madagascar,both hot and cold spots were identified and were separated by the highland region in the center of the island.Most of the eastern island was characterized by cold spots that received less precipitation than did the rest of the island.The presence of increasing hots spots in the densely vegetated areas highlights the urgent need for fire prevention and management in this region.

Mutual promotion of mitochondrial fi ssion and oxidative stress contributes to mitochondrial-DNAmediated infl ammation and epithelial-mesenchymal transition in paraquat-induced pulmonary fibrosis

BACKGROUND:Pulmonary fibrosis(PF)is one of the main causes of death in patients with paraquat(PQ)poisoning.This study aimed to evaluate the relationship between mitochondrial fi ssion and oxidative stress in PQ-induced epithelial-mesenchymal transition(EMT)and PF.METHODS:C57BL/6 mice and MLE-12 cells were exposed to PQ to construct a PF model in vivo and in vitro.Histological changes in the lungs were examined by hematoxylin and eosin(H&E)staining.Mitochondrial morphology was detected by MitoTracker®Deep Red FM or transmission electron microscopy(TEM).Western blotting and immunofluorescence were used to determine the expression of protein.The migration ability of the cells was detected by the cell scratch test.Mitochondrial DNA(mtDNA)levels were assessed by real-time polymerase chain reaction(PCR).Enzyme-linked immunosorbent assay(ELISA)was applied to detect cytokine levels.Superoxide dismutase(SOD)activity and the levels of glutathione(GSH)and malondialdehyde(MDA)were detected by chemichromatometry.RESULTS:PQ exposure caused EMT and PF in vivo and in vitro.PQ destroyed mitochondrial structure and enhanced the expression of dynamin-related protein 1(Drp1),which were accompanied by oxidative stress.Inhibiting mitochondrial fission using mitochondrial division inhibitor-1(Mdivi-1),a selective inhibitor of Drp1,attenuated PQ-induced EMT and oxidative damage.Treatment with N-acetyl-L-cysteine(NAC),an antioxidant,reduced Drp1 expression,attenuated mitochondrial structure damage and inhibited PQ-induced EMT and PF.Both Mdivi-1 and NAC treatment markedly suppressed mtDNA release,the expression of Toll-like receptor 9(TLR9)and phosphorylation(P)-NF-κB p65 as well as cytokines(interleukin 6[IL-6],interleukin-1β[IL-1β],and tumor necrosis factor-α[TNF-α])production.CONCLUSION:Mutual promotion of mitochondrial fission and oxidative stress contributes to EMT in PQ-induced PF,which is associated with the mtDNA/TLR9/NF-κB pathway.

Identifying anthropogenic and natural causes of wildfires by maximum entropy method-based ignition susceptibility distribution models

Turkey has a high potential for wildfires along its Mediterranean coast because of its dense forest cover and mild climate.An average of 250 wildfires occurs every year with more than 10,000 hectares destroyed due to natural and human-related causes.The study area is sensitive to fires caused by lightning,stubble burning,discarded cigarette butts,electric arcing from power lines,deliberate fire setting,and traffic accidents.However,52%of causes could not be identified due to intense wildfires occurring at the same time and insufficient equipment and personnel.Since wildfires destroy forest cover,ecosystems,biodiversity,and habitats,they should be spatially evaluated by separating them according to their causes,considering environmental,climatic,topographic and forest structure variables that trigger wildfires.In this study,wildfires caused by lightning,the burning of agriculture stubble,discarded cigarette butts and power lines were investigated in the provinces of Aydin,Mugla and Antalya,where 22%of Turkey’s wildfires occurred.The MaxEnt method was used to determine the spatial distribution of wildfires to identify risk zones for each cause.Wildfires were used as the species distribution and the probability of their occurrence estimated.Additionally,since the causes of many wildfires are unknown,determining the causes is important for fire prediction and prevention.The highest wildfire occurrence risks were 9.7%for stubble burning,30.2%for lightning,4.5%for power lines and 16.9%by discarded cigarette butts.In total,1,266 of the 1,714 unknown wildfire causes were identified by the analysis of the cause-based risk zones and these were updated by including cause-as signed unknown wildfire locations for verification.As a result,the Area under the ROC Curve(AUC)values were increased for susceptibility maps.

Smoldering charcoal detection in forest soil by multiple CO sensors

Cleaning up residual fires is an important part of forest fire management to avoid the loss of forest resources caused by the recurrence of a residual fire.Existing residual fire detection equipment is mainly infrared temperature detection and smoke identification.Due to the isolation of ground,temperature and smoke characteristics of medium and large smoldering charcoal in some forest soils are not obvious,making it difficult to identify by detection equipment.CO gas is an important detection index for indoor smoldering fire detection,and an important identification feature of hidden smoldering ground fires.However,there is no research on locating smoldering fires through CO detection.We studied the diffusion law of CO gas directly above covered smoldering charcoal as a criterion to design a detection device equipped with multiple CO sensors.According to the motion decomposition search algorithm,the detection device realizes the function of automatically searching for smoldering charcoal.Experimental data shows that the average CO concentration over the covered smoldering charcoal decreases exponentially with increasing height.The size of the search step is related to the reliability of the search algorithm.The detection success corresponding to the small step length is high but the search time is lengthy which can lead to search failure.The introduction of step and rotation factors in search algorithm improves the search efficiency.This study reveals that the average ground CO concentration directly above smoldering charcoal in forests changes with height.Based on this law,a CO gas sensor detection device for hidden smoldering fires has been designed,which enriches the technique of residual fire detection.

Three-dimensional inversion of knot defects recognition in timber cutting

The comprehensive utilization of wood is the main goal of log cutting,but knot defects increase the diffi-culty of rationally optimizing cutting.Due to the lack of real shape data of knot defects in logs,it is diffi cult for detection methods to establish a correlation between signal and defect morphology.An image-processing method is proposed for knot inversion based on distance regularized level set segmentation(DRLSE)and spatial vertex clustering,and with the inversion of the defects existing relative board position in the log,an inversion model of the knot defect is established.First,the defect edges of the top and bottom images of the boards are extracted by DRLSE and ellipse fi tting,and the major axes of the ellipses made coplanar by angle correction;second,the coordinate points of the top and bottom ellipse edges are extracted to form a spatial straight line;third,to solve the intersection dispersion of spatial straight lines and the major axis plane,K-medoids clustering is used to locate the vertex.Finally,with the vertex and the large ellipse,a 3D cone model is constructed which can be used to invert the shape of knots in the board.The experiment was conducted on ten defective larch boards,and the experimental results showed that this method can accurately invert the shapes of defects in solid wood boards with the advantages of low cost and easy operation.

基于FI分类号检索中数据库的选择

本文针对FI分类号在智能检索系统的不同数据库中进行检索的差异进行理论分析和应用验证,提出利用FI分类号进行检索时,选择合适的数据库进行检索,有利于审查员更高效的利用FI分类号进行检索。

用FPGA实现嵌入式视频图像信号实时采集

提出了一种基于FPGA的嵌入式视频图像信号实时采集系统,采用SAA7111A对信号进行A/D变换,并用FPGA与SDRAM实现大容量的双帧缓存。详细说明双口存储器、有限状态机的实现及隔行扫描到逐行扫描的转换、乒乓互锁工作机制等。本系统可用在安全监控、工业图像检测、机器视觉等领域。

基于物联网的智能高压开关柜设计

设计了一种基于物联网技术的智能开关柜。智能开关柜IED采用DSP+ARM双CPU的结构,通过CAN总线、RS-485总线、ZigBee技术等接收智能监测单元监测到的信息,按照IEC61850协议与站控层服务中心进行通信,实现远程监控功能。智能控制单元对柜内开关量、温度、湿度等进行监测,并通过液晶屏、高亮指示条和指示灯显示开关柜状态,同时负责实现开关柜电动操作控制。智能识别单元将设备信息以电子标签的形式预埋在设备中,通过无线射频识别(RFID)技术直接将设备信息传递给智能开关柜IED,由开关柜上传到一体化信息平台,对设备进行准确定位、跟踪。所设计的智能开关柜已成功应用于唐山虹桥变电站,现场工作正常。

基于生态位适宜度的耕地可持续利用评价

耕地可持续利用评价是土地利用研究的重要内容。基于生态位理论,从区域耕地生态系统整体性出发,提出耕地生态元和耕地生态位的概念,并在此基础上构建了耕地可持续利用生态位适宜度评价模型(Fi模型)。然后,将所构建模型应用于河南省焦作市耕地可持续利用评价之中,测度了1997～2006年期间焦作市耕地可持续利用生态位适宜度Fi值。为了便于对照分析,采用限制因子模型(NFmin-i模型)和希尔伯脱空间模型(CHi模型)进行耕地可持续利用生态位适宜度NFmin-i值和CHi值的测算。测算结果表明:(1)1997～2006年期间,Fi值总体上呈递增趋势,从1997年的0.5088增加到2006年的0.6503,表明支撑焦作市耕地可持续利用的自然、经济和社会因子总体上呈良性发展趋势,即耕地可持续利用现实生态位趋于最适生态位。(2)1997～2006年期间,Fi与CHi值各年间的变化规律一致,与NFmin-i值总体变化规律一致,表明运用Fi模型进行耕地可持续利用评价具有较强的科学性和现实性。同时,Fi值有利于从综合角度表征区域耕地总体可持续利用水平。(3)利用最适生态位解释区域耕地可持续利用评价标准,以及运用n维资源(条件)生态位与最适生态位的匹配这一基本思想进行区域耕地可持续利用评价,生态意义明确,便于依据生态位适宜度值的大小及其变化制定区域耕地利用方案和措施。

广西隆林县首起鼠疫暴发流行的特征及原因分析

目的 了解广西 2 0 0 0年发生鼠疫暴发流行的特征 ,初步分析流行原因。方法 以普查、医学观察和追踪调查相结合对人群进行调查 ,用 IHA(间接血凝法 ,Indirect hem agglutination assay,IHA)法测定鼠疫 FI抗体 ,按国家鼠疫诊断标准诊断病人。结果 疫情波及天生桥库区周围 2个乡镇 15个自然屯或单位 ,发生腺型鼠疫病人 4 2例 ,发病率为 1.10 % ,隐性感染率 2 .78% ,第 2代发病率 2 .76 %。流行时间为 3～ 10月。人间鼠疫发病年龄以青少年多见。结论 疫点分布于天生桥库区周围 ,库区鼠、蚤密度增高 。

华北区年高温日数区域平均方法及趋势分析

利用华北地区33个代表站1961—2002年间的年高温日数序列,采用均生函数和最优子集回归法,设计出具有较强拟合能力和未来趋势预测的数理统计模型。该模型能较好地拟合历史实况,其信度达到了99%;也使用该模型做出华北地区2003—2005年3年的高温日数趋势预测,对2003年和2004年做出的趋势预测效果较好。

关于CFI代数

对可交换FI代数(简称CFI代数)的特征进行系统研究,获得(正则)FI代数和CFI代数的一些新的性质;探讨CFI代数与HFI代数、格蕴涵代数及R0代数等逻辑代数之间的关系,得到CFI代数成为正则HFI代数的一个充分必要条件.

日本FI/F-term分类体系在专利技术/功效矩阵中的应用研究

随着创新型企业对专利信息服务品质和服务深度提出越来越高的要求,基于数理统计的基本专利分析方法已经不能满足实际应用需求,针对技术层面深度剖析的专利技术/功效矩阵分析成为能够为企业技术创新提供有力支撑的重要有效手段。本研究根据专利技术/功效矩阵的制作流程,探索性利用日本专利检索体系中的FI/Fterm分类体系进行数据分类标引预处理,并基于实例进行实际应用可行性验证,从而形成面向特定技术主题的专利技术/矩阵分析方法。最后,简单阐述该方法的相关注意事项以及应用前景。

流动注射在线分离富集与石墨炉原子吸收光谱法联用的研究

将流动注射在线预富集系统与石墨炉原子吸收光谱法联用，以Ｃ１８反相键合硅胶为柱材料，以二乙基二硫代氨基甲酸钠为螯合剂，乙醇为洗脱液，以固定体积洗脱方式测定了Ｃｄ、 Ｃｕ和 Ｆｅ，富集倍数分别为 ４０、２９和 １８（与 ３０ ｕＬ进样量相比），检出限（３σ）分别为 ０． ４、３． ０和 ２２ ｎｇ／Ｌ。

鼠疫胶体金法快速诊断试剂盒的研制

目的研制一种敏感、特异、快速并适用于非专业人员的鼠疫胶体金法快速诊断鼠疫FI抗体的试剂盒。方法采用柠檬酸三钠还原法制备胶体金颗粒,标记金黄色葡萄球菌A蛋白作为探针,同时用鼠疫多糖抗原致敏硝酸纤维素膜,共同组装成基于免疫层析原理的胶体金法快速诊断盒。结果间接血凝法检测阳性300份血清标本,胶体金法检测全部为阳性,间接血凝法检测阴性100份血清标本,胶体金法检测全部为阴性,两种方法符合率100%;并且鼠疫胶体金法快速诊断盒不与假结核耶尔森氏菌等相关细菌的免疫血清发生交叉反应。结论鼠疫胶体金法快速诊断盒具有较好的特异性和敏感性,并且具有更简便快速的优点,适合基层单位现场使用。