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基于微波辅助法从玉米秸秆中提取纤维素的研究

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长春师范大学学报 2024年第2期43卷 92-98,111页

作者：王晓惠崔萌吉林化工学院材料科学与工程学院吉林省吉林市132022

玉米秸秆中含有丰富纤维素,是天然的“纤维素库”。若将其提取出来加以利用,将会极大程度地提高秸秆的附加值,为生产生活带来便利。本实验采用微波辅助法处理玉米秸秆粉末,去除其中的半纤维素和木质素,提取其中的秸秆纤维素。利用傅里... 详细信息

玉米秸秆中含有丰富纤维素,是天然的“纤维素库”。若将其提取出来加以利用,将会极大程度地提高秸秆的附加值,为生产生活带来便利。本实验采用微波辅助法处理玉米秸秆粉末,去除其中的半纤维素和木质素,提取其中的秸秆纤维素。利用傅里叶变换红外光谱、X射线衍射以及扫描电镜的方法从形貌、结构以及性能等方面对提取产物进行表征。探究NaOH溶液的质量分数、微波加热时间、微波加热功率、亚氯酸钠浓度以及料液比对提取率的影响,得到从玉米秸秆中提取秸秆纤维素的最佳实验条件为:NaOH溶液质量分数为12%,微波功率为595 w,微波加热时间为9 min,NaClO_(2)浓度为0.3 mol/L。

关键词：玉米秸秆纤维素微波辅助法单因素实验

空间紫外辐射侵蚀环境下SiC/(C_(f)/SiC)陶瓷基复合材料的服役特性演变规律

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固体火箭技术 2024年第3期47卷 370-378页

作者：张佩杨晓辉白龙腾王旭东程晨曹佩航天推进技术研究院西安航天动力研究所复合材料工程中心西安710100

在波长为200~400 nm、最低温度为-50℃、辐射度为3.0 w/m^(2)的紫外辐射环境下,对SiC/(C_(f)/SiC)陶瓷基复合材料分别进行0、10、30、60、120 h辐射实验,结合微观组织结构、组分与力学性能演变情况,研究了紫外辐射服役环境对SiC/(C_(f)/... 详细信息

在波长为200~400 nm、最低温度为-50℃、辐射度为3.0 w/m^(2)的紫外辐射环境下,对SiC/(C_(f)/SiC)陶瓷基复合材料分别进行0、10、30、60、120 h辐射实验,结合微观组织结构、组分与力学性能演变情况,研究了紫外辐射服役环境对SiC/(C_(f)/SiC)陶瓷基复合材料的影响。结果表明,相比于未受紫外辐射的SiC/(C_(f)/SiC)陶瓷基复合材料,当紫外辐射10 h后,SiC/(C_(f)/SiC)陶瓷基复合材料的弯曲强度和模量均有小幅度增加;当紫外辐射超过30 h后,随着辐射时间进一步增加,弯曲强度先增加后降低,而弯曲模量持续降低并且材料表层的裂纹缺陷基本呈现出尺寸和数量均增加的趋势,表明紫外辐射进一步损伤了材料内层。紫外辐射前后SiC/(C_(f)/SiC)陶瓷基复合材料均表现为台阶状的弯曲断裂行为。未进行紫外辐射的SiC/(C_(f)/SiC)陶瓷基复合材料断口以纤维断裂为主;紫外辐射10 h的试样表现出与未辐射试样类似的断裂形貌且纤维受侵蚀不明显;紫外辐射30 h后,试样断口除发现碳纤维断裂现象外,还可发现明显的碳纤维拔出和界面层脱壳现象,碳纤维受到的侵蚀作用较明显;紫外辐射120 h后,SiC/(C_(f)/SiC)陶瓷基复合材料内部碳纤维受到的侵蚀作用进一步加剧,界面层剥离严重,碳纤维端头呈现针状结构。

关键词：陶瓷基复合材料空间环境紫外辐射辐射侵蚀微观组织结构弯曲力学性能

Effect of the span of Australian GPS coordinate time series in establishing an optimal noise model

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Science China Earth Sciences 2015年第11期58卷 523-539页

作者： JIAng weiPing ZHOU xiaohui GNSS Research Center Wuhan University School of Geodesy and Geomatics Wuhan University

The span of coordinate time series affects the determination of an optimal noise model. we analyzed position data recorded for 10 continuous Global Positioning System （GPS） sites from 1998.0 to mid-2009 on the Australian Plate to estimate the best noise model and thereafter obtain the true uncertainties of the velocity, employing the maximum likelihood estimation （MLE） method. MLE was employed to analyze the data in four ways. In the first two analyses, the noise was assumed to be a combination of flicker noise and white noise for the raw time series and spatially filtered time series. In the final two analyses, the spectral indices and amplitudes were simultaneously estimated for a power law noise plus white noise model for the raw time series and spatially filtered time series. we conclude that the noise model of GPS time series in Australia can be best described as the combination of flicker noise and white noise. Velocity uncertainties fall below -0.2 mm/yr when the time span exceeds -9.5 years. A comparison of noise amplitudes and maximum likelihood estimation values between the raw and spatially filtered time series suggests that traditional spatial filtering to remove common-mode errors might not be applicable to the raw time series of this region.

关键词： Australian Plate Global Positioning System time series noise model maximum likelihood estimation

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面向非结构化环境的移动机器人路径规划

组合机床与自动化加工技术 2024年第4期 56-61页

作者：朱伟龙徐晓辉宋涛李锡哲汪曙河北工业大学电子信息工程学院天津300401

针对移动机器人在非结构化环境中路径规划转折点较多、运动效率低与实时避障问题,提出基于改进A*算法融合动态窗口法(DwA)的移动机器人路径规划算法。首先,优化A*算法启发函数,针对估计代价值引入动态权重系数w(n),提高路径规划算法搜... 详细信息

针对移动机器人在非结构化环境中路径规划转折点较多、运动效率低与实时避障问题,提出基于改进A*算法融合动态窗口法(DwA)的移动机器人路径规划算法。首先,优化A*算法启发函数,针对估计代价值引入动态权重系数w(n),提高路径规划算法搜索效率;然后,基于梯度下降算法与SG滤波算法对全局路径进行平滑处理;最后,在全局路径规划的基础上引入DwA算法,提高移动机器人的全局路径规划能力和实时避障能力。实验结果表明,融合算法在提高路径规划搜索效率、平滑路径曲线、动态实时避障等方面具更优的效果。

关键词：非结构化环境移动机器人融合算法路径规划动态避障

Tides and Turbulent Mixing in the North of Taiwan Island

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Advances in Atmospheric Sciences 2019年第3期36卷 313-325,341页

作者： Xiangzhou SOng Dexing wU xiaohui XIE State Oceanic Administration Ministry of Nat-ural Resources Physical Oceanography Laboratory Ocean University of China National Marine Environmental Forecasting Center State Oceanic Administration Horn Point Laboratory University of Maryland Center for Environmental Science

Microstructure and hydrological profiles were collected along two cross-shelf sections from the deep slope to the shallow water in the north of Taiwan Island in the summer of *** the tidal currents on the shelf were dominated by the barotropic tide with the current ellipse stretched across the shelf,significant internal tides were observed on the *** depth-mean turbulent kinetic energy(TKE)dissipation rate on the shelf was 10^-6w kg^-1,corresponding to a diapycnal diffusivity of 10^-2 m^2s^-*** depth-mean TKE dissipation rate on the slope was 1×10^-7 wkg^-1,with diapycnal diffusivity of 3×10^-4m^2s^-*** shear instability associated with internal tides largely contributed to the TKE dissipation rate on the slope from the surface to 150 m,while the enhanced turbulence on the shelf was dominated by tidal or residual current dissipations caused by friction in the thick bottom boundary layer(BBL).In the BBL,the Ekman currents associated with the northeastward Taiwan warm Current were identified,show.ng a near-bottom velocity spiral,which agreed well with the analytical bottom Ekman solution.

关键词： microstructure observations turbulent mixing internal tides bottom boundary layer bottom Ekman spiral

Effects of Pulsed Magnetic Field on Microsegregation of Solute Elements in a Ni-Based Single Crystal Superalloy

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Journal of Materials Science & Technology 2017年第1期33卷 105-110页

作者： Yingju Li Yuefei Teng xiaohui Feng Yuansheng Yang Superalloy Division Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

The effects of a pulsed magnetic field （PMF） on the microsegregation of solute elements during directional solidification of a Ni-based single crystal superalloy were experimentally investigated, and the results show that the PMF significantly affects the microsegregation of Al, Ti, Co, Mo and w elements in the alloy. However, the distribution behavior differs for both positive and negative segregation elements. with the PMF, the microsegregation of negative segregation elements, Co and w, was restrained effectively, while that of positive segregation elements, A1, Ti and Mo, was aggravated. A segregation model was estab- lished to reveal the distribution mechanism of the elements with PME It is considered that, under the action of PME the jumping of solute atoms from the liquid phase to solid phase is hindered, but the jumping of solute atoms from the solid phase into liquid phase is promoted during solidification. As a result, the effective distribution coefficient of the solute atoms is reduced, which leads to the reduction of microsegregation of negative segregation elements and aggravation of microsegregation of positive segregation elements.

关键词： Pulsed magnetic field Segregation Superalloy Distribution coefficient

血清YKL-40、TNF-α与糖尿病视网膜病变相关性的临床研究

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临床眼科杂志 2024年第2期32卷 127-132页

作者：萨其如拉蔺晓慧内蒙古医科大学呼和浩特010020 内蒙古自治区人民医院

目的研究血清中人软骨糖蛋白-39(YKL-40)、肿瘤坏死因子-α(TNF-α)与糖尿病性视网膜病变(DR)的相关性及临床指标间的相关性,探讨YKL-40及TNF-α在DR发生发展中所起的作用,希望用于DR高危人群的筛选、预测及诊断。方法回顾性系列病例研... 详细信息

目的研究血清中人软骨糖蛋白-39(YKL-40)、肿瘤坏死因子-α(TNF-α)与糖尿病性视网膜病变(DR)的相关性及临床指标间的相关性,探讨YKL-40及TNF-α在DR发生发展中所起的作用,希望用于DR高危人群的筛选、预测及诊断。方法回顾性系列病例研究。本研究旨在比较三种不同类型的糖尿病患者临床指标及YKL-40、TNF-α水平,分别是单纯2型糖尿病无视网膜病变患者(DM组)、非增生性糖尿病性视网膜病变患者(NPDR组)、增生性糖尿病性视网膜病变患者(PDR组)以及选取同期行白内障手术患者为空白对照组(ngT组),其时间选取为2021年3月至2022年6月在我院住院治疗的患者。所有研究对象都应记录并测量其性别、年龄、病程、身高、体重等基本信息,并计算出体质指数(BMI)。测定收缩压(SBP)、舒张压(DBP)。抽取空腹肘静脉血,分离血清。空腹静脉血糖(FBG)、糖化血红蛋白(HbA1c)、甘油三脂(TG)、总胆固醇(TC)、低密度脂蛋白(LDL-C)、高密度脂蛋白(HDL-C)、空腹胰岛素(FINS)等临床指标并计算胰岛素抵抗指数(HOMA-IR)。采用酶联免疫法检测血清中YKL-40及TNF-α的浓度,进一步分析与其他临床指标之间的关系。结果血清YKL-40浓度PDR组为(67.93±8.52)ng/mL,高于NPDR组的(59.29±7.87)ng/mL,DM组的(50.08±10.01)ng/mL及ngT组的(39.07±9.59)ng/mL,差异均有统计学意义(均PngT组的(38.7±8.32)Pg/mL,差异均有统计学意义(均P<0.001)。血清YKL-40与病程、糖化血红蛋白、静脉血糖、胰岛素抵抗指数均呈正相关(均P<0.05);血清TNF-α与病程、糖化血红蛋白、静脉血糖、胰岛素抵抗指数呈正相关(均P<0.05)。血清YKL-40的ROC曲线下的面积(0.894);血清TNF-α的ROC曲线下的面积(0.927);二者联合诊断时的ROC曲线下的面积(0.935)。结论YKL-40及TNF-α水平在NC、DM、NPDR及PDR四组中均逐渐升高,二者可能参与到DR的发病过程;YKL-40及TNF-α的水平升高可能对DR的危险性更高。

关键词：人软骨糖蛋白-39 肿瘤坏死因子-α 糖尿病视网膜病变

慢性射血分数降低的缺血性心肌病患者心功能和甲状腺功能的相关性分析

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中国循证心血管医学杂志 2024年第3期16卷 279-282页

作者：张晓慧袁河新河南省直第三人民医院心血管内科郑州450000

目的探讨慢性射血分数降低的缺血性心肌病(ICM)患者心功能和甲状腺功能的相关性。方法选取2020年5月至2022年5月于河南省直第三人民医院收治的ICM患者110例为研究对象,根据左室射血分数(LVEF)将患者分为对照组(LVEF≥40%,n=49)和研究组(... 详细信息

目的探讨慢性射血分数降低的缺血性心肌病(ICM)患者心功能和甲状腺功能的相关性。方法选取2020年5月至2022年5月于河南省直第三人民医院收治的ICM患者110例为研究对象,根据左室射血分数(LVEF)将患者分为对照组(LVEF≥40%,n=49)和研究组(LVEF0.05);研究组LVEDD、LAD水平均高于对照组(P0.05)。研究组FT3水平低于对照组、TSH水平高于对照组(P0.05);Ⅲ、Ⅳ级组FT3水平低于Ⅰ级组、TSH水平均高于Ⅰ级组,Ⅳ级组FT3水平低于Ⅱ级组、TSH水平均高于Ⅱ级组(P<0.05)。NYHA心功能分级与TSH呈正相关(P<0.05);LVEDD与FT4、FT3均呈负相关,与TSH呈正相关(P<0.05);LAD与FT4、FT3均呈负相关,与TSH呈正相关(P<0.05)。结论慢性射血分数降低的ICM患者血清FT3水平较低,与LVEDD及LAD呈负相关;慢性射血分数降低的ICM患者血清TSH水平较高,与NYHA心功能分级、LVEDD及LAD呈正相关。

关键词：缺血性心肌病射血分数心功能甲状腺功能

Heat Leakage Numerical Investigation of a Compound Parabolic ConcentratorPulsating Heat Pipe Solar Collector

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Journal of Thermal Science 2022年第5期31卷 1318-1326页

作者： XU Rongji CHEN Jingyan ZHAng xiaohui w.ng Ruixiang XU Shuhui Beijing Engineering Research Center of Sustainable Energy and Buildings Beijing University of Civil Engineering and ArchitectureBeijing100044China

As a new type of equipment for solar medium temperature utilization, the compound parabolic concentrator-pulsating heat pipe solar collector(CPC-PHPSC) uses pulsating heat pipe(PHP) as an endotherm, which can realize efficient energy conversion. The design of proper concentration ratio of compound parabolic concentrator(CPC) ensures that the incident sunlight can be concentrated on the evaporator section surface of PHP without solar tracking system. The objective of the present work is to study the influence of solar radiation intensity, air speed, material thickness(glass and insulation board) and tilt angle on the thermal performance of the new collector, which is difficult to control in the experiment. The heat leakage process and characteristics of the CPC-PHPSC were numerically studied by establishing a 3D numerical model of the collector unit. The results show that the theoretical collector efficiency of CPC-PHPSC reaches 74.5%, which is consistent with the experimental results. During operation, the heat collection performance is the best when the tilt angle is 45° and the solar radiation intensity is 1000 w/m^(2), while the excessive air speed will increase the convective heat loss. Increasing the thickness of insulation board and glass has little effect on the collector efficiency.

关键词： solar collector CPC(Compound Parabolic Concentrator) pulsating heat pipe solar irradiation intensity glass thickness