机械力化学技术制备磷酸法活性炭及其碘吸附性能的研究     

李素琼  黄彪  林冠烽  陈翠霞  黄锦峰 《南平师专学报》2011,30(5):29-35

研究采用机械力化学技术制备了吸附性能良好的活性炭。试验采用Plackett—Burman（PB）实验设计和Box—BehnkenDesign（BBD）设计法对影响活性炭碘吸附值的6个条件进行筛选优化。PB实验设计与统计学分析表明酸屑比、研磨时间、活化温度、磷酸浓度是影响活性炭碘吸附值的四个关键因素。以碘吸附值为响应目标,对四因素进行BBD设计,并经响应面法优化分析得到影响活性炭碘吸附值的二阶模型,确定了机械力化学技术制备磷酸活性炭的较优操作条件为：酸屑比2．00,研磨时间22min,活化温度406℃,磷酸浓度20％,活性炭的碘吸附值达1195．23mg／g。  相似文献   

基于VAR模型通货膨胀影响因素的实证分析     

白金  蒋木子 《丹东师专学报》2011,(4):63-69

分析了十年我国两次比较严重的通货膨胀的成因,使用2001年1月—2010年9月的季度数据,在构建稳定的VAR模型基础上,通过建立协整方程,运用格兰杰因果检验以及脉冲响应函数的方法,对其进行分析。结果表明：经济增长、广义货币供给量、房地产销售价格指数、外汇储备与CPI之间存在长期的协整关系;长期内以房地产为代表的资产价格对CPI的冲击较大,短期内外汇储备推高CPI的效果最为显著。  相似文献   

平板叶片的相关激励响应试验     

杜建建  李舜酩  张袁元  方立成 《实验室研究与探索》2011,30(1)

为了研究不同频率的激振力叠加作用下平板叶片的位移响应变化,在平板叶片上选取激励点和多个响应点进行相关性激励试验。试验中,首先运用设计的加法器对频率为112、280和583 Hz的简谐力分别进行叠加,然后以压电陶瓷片作为激振器对平板叶片进行激励,同时以压电陶瓷片作为感应器采集位移响应,最后应用谱分析方法对位移响应进行分析。通过对比不同频率的激振力叠加作用下的位移响应自功率谱幅值,发现自功率谱幅值比单一频率激振力作用时有所降低,并且降低的程度和与其叠加的激振力频率的大小和个数有关,叠加的个数越多,降低的程度越大。  相似文献   

基于MATLAB的结构可靠度分析方法研究   总被引：1，自引：1，他引：0  

李远瑛  张德生 《嘉应学院学报》2011,29(2):45-48

基于结构可靠度分析方法—JC法、蒙特卡罗法和响应面法的基本原理,利用MATLAB软件对算例编制了相应计算程序,并对计算结果进行了比较.计算结果表明,利用MATLAB可以编制结构可靠度分析程序,计算结果较快,数据合理,并为复杂结构的可靠性分析提供参考.  相似文献   

论美国文化应答式教育的涵义与启示     

陈越 《贵州教育学院学报》2011,(12):80-84

文化应答式教育是利用学生的语言文化背景进行教学,促进学生在学业上获得成功的一种教育模式,主要针对少数民族学生的教育。我国的教育研究在这个方面尚处于起始阶段。借鉴美国的教育模式对我国这样一个多民族国家的教育有着极其重大的指导意义。  相似文献   

两种方式的健步走对边缘性血脂升高的中年男性血脂及肺通气功能的研究     

孔淑珍  张葆欣  李洁妮  韩国庆  温晓妮  张明军 《北京体育大学学报》2017,40(9):54-59

摘要：目的：探讨2种方式的健步走对边缘性血脂升高中年男性脑力劳动者血脂及肺功能的影响。方法：选取西安市3所高校从事脑力劳动的科研工作者，筛选出符合（血脂水平分层标准）边缘性血脂升高标准的受试者48人，随机分成匀速组和变速组各24人，实施为期12周的健步走。2组采用的运动强度为，匀速组在第二和第三个10～15 min以60﹪～70﹪HRmax为主，变速组以60﹪～70﹪HRmax和70﹪～80﹪HRmax为主，每周4次，每次40～60 min。重点监测受试者运动前、运动4周、运动12周的血脂六项（TC、TG、HDL-C、LDL-C、Apoa1/Apob）和肺通气功能指标（VC、FVC、FEV1/FVC﹪、MVV、VC/Kg）。结果：1）与运动前比较，运动6周，匀速组血脂及肺通气功能各指标无显著性变化（p>0.05）；变速组TC显著降低（p＜0.05），FEV1/FVC﹪、MVV、VC/Kg显著升高（p＜0.05）。运动12周，匀速组TC、TG显著降低（p＜0.05），FEV1/FVC﹪、MVV、VC/Kg显著增高（p＜0.05）；变速组血脂各指标（除Apoa1/Apob外）和肺功能指标（除FVC外）均有显著差异（p＜0.01或p＜0.05）。2）组间比较：运动6周，两组血脂与肺功能各指标无显著性差异（p>0.05）。运动12周，具有显著性差异（p＜0.05）的指标为HDL-C、LDL-C、MVV。3)在不同的运动周期，血脂和肺功能指标的变化幅度均有显著性变化，运动12周明显优于运动6周，变速组变化幅度优于匀速组。结论：1)匀速健步走运动12周，具有明显的调脂效果和提高肺通气功能；变速健步走运动6周，对血脂异常和肺通气功能有显著的改善。运动12周，调脂效果非常显著基本回归正常范围，肺功能显著提高。2)2种方式的健步走，强度较高的变速运动对血脂异常的调脂效果和肺通气功能的提高显著优于匀速运动。  相似文献   

Physical activity and nutrition guidelines to help with the fight against COVID-19     

Kayvan Khoramipour  Aref Basereh  Amirhoseein Ahmadi Hekmatikar  Lindy Castell  Ruheea Taskin Ruhee 《Journal of sports sciences》2021,39(1):101-107

ABSTRACT

As the world is witnessing the epidemic of coronavirus disease 2019, emerging genetics and clinical pieces of evidence suggest a similar immunopathology to those of severe acute respiratory syndrome and Middle East respiratory syndrome. Staying at home to prevent the spread of the virus and consequently being largely inactive is associated with unintended consequences. These can actually enhance the infection risk and exacerbate poor health conditions including impaired immune function. Physical activity is a feasible way of improving health, particularly physical and mental health in a time of social isolation. However, people with certain health conditions in these circumstances may need a special physical activity programme in addition to any exercise they may already be performing via online programmes. This review aims to provide practical guidelines during the COVID-19 quarantine period. We suggest performing aerobic, resistance training, respiratory muscle training and yoga in the healthy, and in those with upper respiratory tract illness, patients with lower respiratory tract illness should be restricted to respiratory muscle training and yoga. In addition, vitamins D and C, omega-3 fatty acids, and regular consumption of fruit and vegetables might be considered as nutritional aids to support the immune system in those affected by COVID-19.  相似文献   

An NCME Instructional Module on Polytomous Item Response Theory Models     

Randall David Penfield 《Educational Measurement》2014,33(1):36-48

A polytomous item is one for which the responses are scored according to three or more categories. Given the increasing use of polytomous items in assessment practices, item response theory (IRT) models specialized for polytomous items are becoming increasingly common. The purpose of this ITEMS module is to provide an accessible overview of polytomous IRT models. The module presents commonly encountered polytomous IRT models, describes their properties, and contrasts their defining principles and assumptions. After completing this module, the reader should have a sound understating of what a polytomous IRT model is, the manner in which the equations of the models are generated from the model's underlying step functions, how widely used polytomous IRT models differ with respect to their definitional properties, and how to interpret the parameters of polytomous IRT models.  相似文献   

Automated Scoring of Constructed‐Response Science Items: Prospects and Obstacles     

Ou Lydia Liu  Chris Brew  John Blackmore  Libby Gerard  Jacquie Madhok  Marcia C. Linn 《Educational Measurement》2014,33(2):19-28

Content‐based automated scoring has been applied in a variety of science domains. However, many prior applications involved simplified scoring rubrics without considering rubrics representing multiple levels of understanding. This study tested a concept‐based scoring tool for content‐based scoring, c‐rater?, for four science items with rubrics aiming to differentiate among multiple levels of understanding. The items showed moderate to good agreement with human scores. The findings suggest that automated scoring has the potential to score constructed‐response items with complex scoring rubrics, but in its current design cannot replace human raters. This article discusses sources of disagreement and factors that could potentially improve the accuracy of concept‐based automated scoring.  相似文献   

Managing What We Can Measure: Quantifying the Susceptibility of Automated Scoring Systems to Gaming Behavior     

Derrick Higgins  Michael Heilman 《Educational Measurement》2014,33(3):36-46

As methods for automated scoring of constructed‐response items become more widely adopted in state assessments, and are used in more consequential operational configurations, it is critical that their susceptibility to gaming behavior be investigated and managed. This article provides a review of research relevant to how construct‐irrelevant response behavior may affect automated constructed‐response scoring, and aims to address a gap in that literature: the need to assess the degree of risk before operational launch. A general framework is proposed for evaluating susceptibility to gaming, and an initial empirical demonstration is presented using the open‐source short‐answer scoring engines from the Automated Student Assessment Prize (ASAP) Challenge.  相似文献