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基于课程学习过程性数据的成绩预测研究

软件导刊 2024年第8期23卷 287-293页

作者：姚河花张彤张顺赵亚娟青海大学计算机技术与应用学院青海西宁810016

学生成绩预测在智慧教育领域备受瞩目,通过分析课程过程性学习数据预测期末考试成绩对于提高教学质量至关重要。选取2017-2019年青海大学程序设计基础(c)课程的学生学习数据作为研究对象,使用支持向量机、随机森林、多层感知器、极限梯... 详细信息

学生成绩预测在智慧教育领域备受瞩目,通过分析课程过程性学习数据预测期末考试成绩对于提高教学质量至关重要。选取2017-2019年青海大学程序设计基础(c)课程的学生学习数据作为研究对象,使用支持向量机、随机森林、多层感知器、极限梯度提升树和多元线性回归5种机器学习模型,根据过程性学习数据提前评估学生的期末表现,同时采用均方根误差、确定系数、平均绝对误差和均方误差评价模型预测性能。实验结果表明,5种机器学习模型在成绩预测方面均有较好表现,其中极限梯度提升树性能最佳。采用机器学习模型深入分析学生的过程性学习数据并提前预测其期末表现可以帮助教师优化教学过程,使学生获得更好的学习成绩和体验。

关键词：成绩预测教学数据机器学习

节能降耗对经济绿色发展的影响研究——基于中国2007-2021年31个省级面板数据的实证

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生态经济 2024年第10期40卷 173-180页

作者：刘志雄张久玥黄翀广西民族大学经济学院广西南宁530007

利用2007-2021年中国31个省份(港澳台地区除外)的面板数据,采用引入能源和资源因素的c-D函数和熵权法测算各省级的经济绿色发展和节能降耗水平,实证检验了节能降耗对经济绿色发展的影响机制。研究发现:在空间布局上,节能降耗可推动经济... 详细信息

利用2007-2021年中国31个省份(港澳台地区除外)的面板数据,采用引入能源和资源因素的c-D函数和熵权法测算各省级的经济绿色发展和节能降耗水平,实证检验了节能降耗对经济绿色发展的影响机制。研究发现:在空间布局上,节能降耗可推动经济绿色发展,且不同区域助推效果存在差异,东部地区和中西部的低水平节能降耗地区效果更显著。从结构异质性来看,这种助推效果主要依靠能源效率和节能投入的边际增长,合理的一次能源消费和产业结构有利于经济绿色发展。影响机制研究发现,技术创新和环境规制可助推经济绿色发展。基于此,提出加强地区能源建设、因地制宜推进能源建设、加大能源科技创新与构建能源节约环境等政策建议。

关键词：节能降耗经济绿色发展中介效应

Assessment of biological changes in wheat seedlings induced by ^(12)c^(6+)-ion irradiation

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Nuclear Science and Techniques 2008年第3期19卷 138-141页

作者： zhang Luwei zhang Hong zhang Xiaofu ZHU Jianlan college of Grassland Science Gansu Agricultural University Lanzhou 730070 China Department of Medical Physics Institute of Modern Physics Chinese Academy of Sciences Lanzhou 730000 China Key Laboratory of Grassland-Ecosystem Pratacultural College Gansu Agricultural University Lanzhou 730070 China Sino-US center for Grazingland Ecosystem Sustainability Lanzhou 730070 China

The present study was designed to evaluate the effect of 12 6+ c ion beam (10～80 Gy) on biological changes of wheat seedlings. Reactive oxygen species (ROS)-related biomarkers and the quantification of plant survival and growth were examined at 10 day after carbon ions irradiation (LET: 30.8 keV/μm). The results showed that heavy ions obviously enhanced ROSs reflected by the production of O2 and H2O2 as well as TBARS, and - treatment with 20 Gy achieved the peak value, suggesting that higher mutagenic potential may occur at 20 Gy. Simultaneously, increase of SOD activity was induced by heavy ions to counteract ROS accumulation. On the other hand, higher doses at 40 and 80 Gy inhibited wheat growth and survival in comparison with the control, and reversely lower doses at 10 or 20 Gy stimulated wheat growth and survival. In conclusion, the above observations imply that a dose range of 20~40 Gy is likely promised for wheat mutation breeding.

关键词：离子电离辐射植物生长辐射损伤

c/cO_(2)摩尔比对cO_(2)气氛流态化预热活化半焦特性的影响

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煤炭学报 2024年第4期49卷 2067-2075页

作者：张海霞虎慧朱治平郑思奇齐晓宾中国科学院工程热物理研究所北京100190 中国科学院大学北京100049

我国工业领域涉及的行业多,碳减排压力大。富氧燃烧是燃烧中碳捕集的核心工艺,将流态化富氧预热活化与工业窑炉富氧燃烧过程耦合是拓宽燃料适应性、实现工业领域燃烧中碳捕集的新途径。利用小型流化床连续给料实验系统,在1050℃、cO_(2... 详细信息

我国工业领域涉及的行业多,碳减排压力大。富氧燃烧是燃烧中碳捕集的核心工艺,将流态化富氧预热活化与工业窑炉富氧燃烧过程耦合是拓宽燃料适应性、实现工业领域燃烧中碳捕集的新途径。利用小型流化床连续给料实验系统,在1050℃、cO_(2)流化速度为0.17 m/s条件下,通过调整给料速度,考察c/cO_(2)摩尔比(cc比)对半焦原料(Rc)流态化预热活化的影响,分析煤气组分及低位热值,计算cO_(2)还原率,表征粗颗粒活化半焦(Lc)和细颗粒活化半焦(Fc)的比表面积、孔隙结构和碳架结构,并利用高温管式炉热天平实验系统评价了Rc和Fc在1300℃条件下的反应活性。结果表明:采用流态化预热活化技术实现了cO_(2)的资源化利用,制备出富cO煤气,cc比由1增至4时,煤气中cO+H_(2)体积分数由69.24%增至79.08%,cO体积分数最高为68.96%,cO_(2)体积分数由29.48%降至20.13%,cO_(2)还原率由50.37%提升至57.56%,煤气低位热值由8.69 MJ/m^(3)增至9.83 MJ/m^(3),是参考文献所述工程产出煤气低位热值的1.55~1.88倍,有利于窑炉系统的着火及稳定燃烧。随cc比增加,Fc和Lc的比表面积先增加后减小,Fc和Lc的最高比表面积分别为291.21 m^(2)/g和477.15 m^(2)/g,分别为半焦原料的48倍和78倍;Fc和Lc具有丰富的微孔结构,且石墨化程度比Rc降低、活性点位增加;Fc和Lc的微孔面积占比表面积的54.93%~68.42%;相比较而言,Lc具有更高的比表面积和增量孔容积,主要是由于Lc在反应器内的停留时间较长,促进了孔隙的发展,形成了大量微孔。不同cc比条件下所得Fc的反应活性指数R0.5、质量平均反应速率均高于Rc,表明Fc具有较高的反应活性,可预测在高温气固活化态热燃料燃烧过程中,Fc将实现高效转化。提出了碳基燃料流态化富氧预热活化-高温气固活化态热燃料富氧燃烧的新思路,获得了cc比对cO_(2)气氛流态化预热活化半焦特性的影响规律,揭示了cO_(2)作为碳和氧载体的积极作用,研究结果为流态化预热活化技术在工业窑炉富氧燃烧行业的应用提供了数据支持。

关键词：半焦流态化预热活化二氧化碳反应活性

Influence of sample preparation on nanoindentation results of twinninginduced plasticity steel

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International Journal of Minerals,Metallurgy and Materials 2021年第5期28卷 877-887页

作者： Jiali zhang Stefan Zaefferer Institute for Materials Applications in Mechanical Engineering RWTH Aachen UniversityAachen 52062Germany Max-Planck-Institut für Eisenforschung Düsseldorf 40237Germany

Nanoindentation is an attractive characterization technique,as it not only measures the local properties of a material but also facilitates understanding of deformation mechanisms at submicron ***,because of the complex stress-strain field and the small scale of the deformation under the nanoindenter,the results can be easily influenced by artifacts induced during sample *** this work,a systematic study was conducted to better understand the influence of sample preparation methods on the nanoindentation results of ductile *** experiments were conducted on a steel(Fe-22Mn-0.65c,wt%)with twinning-induced plasticity(TWIP),which was selected for its large grain size and sensitivity to different surface preparation *** grouping the results obtained from each nanoindent,chemical polishing was found to be the best sample preparation method with respect to the resulting mechanical properties of the *** contrast,the presence of a deformation layer left by mechanical polishing and surface damage induced by focused ion beam(FIB)scanning were confirmed by the dislocation-nucleation-induced pop-in events of nanoindentation.

关键词： TWIP steels nanoindentation mechanical polishing chemical polishing pop-in

The Regulatory Effect of Natural Killer cells:Do "NK-reg cells" Exist?

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cellular & Molecular Immunology 2006年第4期3卷 241-254页

作者： cai zhang Jian zhang Zhigang Tian Institute of Immunopharmacology ＆ Immunotherapy School of Pharmaceutical Sciences Shandong University Jinan 250012 Shandong China Institute of Basic Medical Sciences Shandong Academy of Medical Sciences Jinan 250062 Shandong China

The most important progress in immunology in the last decade is the description of regulatory lymphocytes, among which Treg cells and regulatory NKT cells are much attractive to not only immunologists but also almost all biomedical researchers. Meanwhile, it is noted that NK cells are not only ＂Killers＂ but also regulate innate and adaptive immunity, especially in early stage, by secreting cytokines and cell-cell contact. In this review, we are going to briefly summarize the progresses in regulatory lymphocytes including T cells （Treg, Tr1, Th3）, NKT cells and NK cells, and then extensively introduce the positive regulatory function of NK cells in both normal immune response and in disease condition （tumor, infection and autoimmunity）, and finally, to focus on the most latest progression in the negative regulatory effects of NK cells on normal and pathogenic immune response. In conclusion, we speculate that a ＂regulatory NK （NK-reg）＂ cell subset exist and need to explore.

关键词： natural killer cell regulatory T cell innate immunity immune regulation

Hαcounterparts of X-ray bright points in the solar atmosphere

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Science china(Physics,Mechanics & Astronomy) 2012年第5期55卷 907-914页

作者： zhang Ping FANG cheng zhang QingMin School of Astronomy and Space Science Nanjing UniversityNanjing 210093China Key Lab of Modern Astronomy and Astrophysics Nanjing UniversityMinistry of EducationNanjing 210093China

X-ray bright points （XBPs） are small-scale brightenings in the solar corona. Their counterparts in the lower atmosphere, how- ever, are poorly investigated. In this paper, we study the counterparts of XBPs in the upper chromosphere where the Hot line center is formed. The XBPs were observed by the X-ray Telescope （XRT） aboard the Hinode spacecraft during the observing plan （HOP0124） in August 2009, coordinated with the Solar Magnetic Activity Research Telescope （SMART） in the Kwasan and Hida Observatory, Kyoto University. It is found that there are 77 Hot brightenings in the same field of view of XRT, and among 57 XBPs, 29 have counterparts in the Hot channel. We found three types of relationship： Types a, b and c, correspond- ing to XBPs appearing first, Hot brightenings occurring first and no respective correspondence between them. Most of the strong XBPs belong to Type a. The Hot counterparts generally have double-kernel structures associated with magnetic bipoles and are cospatial with the footpoints of the XBP loops. The average lag time is -3 minutes. This implies that for Type a the heating, presumably through magnetic reconnection, occurs first in the solar upper atmosphere and then goes downwards along the small-scale magnetic loops that comprise the XBPs. In this case, the thermal conduction plays a dominant role over the non-thermal heating. Only a few events belong to Type b, which could happen when magnetic reconnection occurs in the chromosphere and produces an upward jet which heats the upper atmosphere and causes the XBP. About half of the XBPs belong to Type c. Generally they have weak emission in SXR. About 62% Hot brightenings have no corresponding XBPs. Most of them are weak and have single structures.

关键词： solar activity bright points small-scale brightenings

Responses of microbial activities and soil physical-chemical properties to the successional process of biological soil crusts in the Gurbantunggut Desert,Xinjiang

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Journal of Arid Land 2015年第1期7卷 101-109页

作者： Bingchang zhang XiaoBing ZHOU YuanMing zhang Key Laboratory of Biogeography and Bioresources in Arid Land Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences

Biological soil crusts （BScs） are capable of modifying nutrient availability to favor the establishment of biogeochemical cycles. Microbial activities serve as critical roles for both carbon and nutrient transformation in BScs. However, little is known about microbial activities and physical-chemical properties of BScs in the Gurbantunggut Desert, Xinjiang, china. In the present research, a sampling line with 1-m wide and 20-m long was set up in each of five typical interdune areas selected randomly in the Gurbantunggut Desert. Within each sampling line, samples of bare sand sheet, algal crusts, lichen crusts and moss crusts were randomly collected at the depth of 0-2 cm. Varia- tions of microalgal biomass, microbial biomass, enzyme activities and soil physical-chemical properties in different succession of BScs were analyzed. The relationships between microalgal biomass, microbial biomass, enzymatic activities and soil physical-chemical properties were explored by stepwise regression. Our results indicate that micro- algal biomass, microbial biomass and most of enzyme activities increased as the BScs developed and their highest values occurred in lichen or moss crusts. Except for total K, the contents of most soil nutrients （organic c, total N, total P, available N, available P and available K） were the lowest in the bare sand sheet and significantly increased with the BScs development, reaching their highest values in moss crusts. However, pH values significantly decreased as the BScs developed. Significant and positive correlations were observed between chlorophyll a and microbial biomass c. Total P and N were positively associated with chlorophyll a and microbial biomass c, whereas there was a significant and negative correlation between microbial biomass and available P. The growth of cyanobacteria and microorganism contributed c and N in the soil, which offered substrates for enzyme activities thus increasing enzyme activities. Probably, improvement in enzyme

关键词： chlorophyll a microbial biomass c soil enzyme physical-chemical properties biological soil crusts

Anti-inflammatory and Immunomodulatory Effects of Marine n-3 Polyunsaturated Fatty Acids on Human Health and Diseases

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Journal of Ocean University of china 2019年第2期18卷 481-492页

作者： zhang Yiran MIN Junxia zhang Lijuan The First Affiliated Hospital Institute of Translational Medicine School of Medicine Zhejiang University Institute of cerebrovascular Diseases Affiliated Hospital of Qingdao University

The pharmaceutical effects of n-3 polyunsaturated fatty acids(n-3 PUFAs) as dietary nutrients on human health and diseases have gained much attention and are investigated for decades. Docosahexaenoic acid(DHA), eicosapentaenoic acid(EPA) and docosapentaenoic acid(DPA) are the three major n-3 PUFAs enriched in marine organisms, such as fish, shrimp, algae, and so on. It has been well known that n-3 PUFAs, especially DHA and EPA, are beneficial in reducing the risk of cardiovascular and cerebrovascular diseases. Accumulating evidence suggests that n-3 PUFAs might cure inflammatory diseases through several mechanisms, such as plasma membrane remodeling of lymphocytes, down-regulating pro-inflammatory cytokines, and alternating adhesion molecule expressions. Several molecular targets of n-3 PUFAs on immune-regulation have also been identified, such as GPR120(FFA4), protein kinase c(PKc), and PPAR-γ. However, it remains inconclusive if dietary n-3 PUFAs function the same both in vitro and in vivo based on cohort studies. This review will focus on the molecular targets and mechanisms of anti-inflammatory and immunomodulatory effects of n-3 PUFAs on human health and diseases, such as obesity, tumor, diabetes, and autoimmune diseases.

关键词： n-3 polyunsaturated fatty acids immune-regulation anti-inflammation mechanism