室内空气环境的CFD评价方法

介绍了计算流体动力学(CFD)的k-!模型、空气年龄控制方程、人体热舒适性指标PMV,利用CFD评价了某办公室室内空气环境。     

延安城市居民红色记忆的建构路径与代际差异

作为贯通于中国现当代社会进步与发展的典型文化现象,红色记忆宏观层面的书写、建构、传承等话题得到了广泛的关注与探讨,但个体层面的红色记忆研究相对空缺并亟待推进。为此,本文以红色资源富集的延安城市核心区为案例地,借助世代研究法,通过对36位当地居民的深度访谈,明晰了红色记忆"宏观—微观"的建构路径与结果,并诠释了延安老中青三代城市居民的红色记忆代际差异。研究发现,宏观层面的记忆要素挖掘、叙事表达与资源活化构筑了居民红色记忆的编码、选择与巩固过程,促使当地居民生成富有时代特色的红色记忆内容,并最终构建了老中青三代权威性、功能性及反思性的差异性红色记忆体系。研究结果折射出记忆建构的社会力量与时代变迁对个体记忆塑造的重要意义,并为规范开展红色记忆实践,推进红色记忆薪火相传提供了理论参照。     

1995～2000年河西走廊土地利用变化研究

目前,人类面临的许多环境问题都与土地利用/覆被变化有关。利用1995和2000年两个时期的Landsat5的4、3、2(RGB)波段合成影像的解译结果,采用中国科学院资源环境数据库中的全国1∶100000土地资源利用分类系统,基于GIS软件平台ArcInfo7.1中文版对河西走廊近5年来的土地利用变化进行了研究。结果表明,近5年来,河西走廊发生了大规模的土地利用变化:①土地利用类型斑块数量和总边缘长度基本呈增加之势,表明研究区内景观的破碎程度增加;②土地利用结构变化表现出耕地、林地和建设用地有明显增加,水域、草地和未利用地都呈减少趋势,反映出区域城镇化进程的加快和生态环境恶化的趋势;③土地利用变化的区域差异明显,表现为地处河西走廊西段的酒(泉)嘉(峪关)地区以耕地、林地、水域和建设用地增加,未利用地和草地减少为主要变化特点,走廊中段的张掖市以耕地、林地和建设用地增加,草地、水域和未利用地减少为主要变化特点,走廊东段的武(威)金(昌)地区以耕地和建设用地增加,草地和水域减少为主要变化特点。     

1953-2016年中国粮食补贴政策分析

粮食补贴政策是确保粮食增产、农民增收和国家粮食安全的重要举措。论文分3个阶段系统梳理和分析了1953-2016年期间实施的粮食补贴政策特点和演变趋势,分4个环节即粮食生产、加工、存储、销售环节分析了补贴政策的时空变化,总结提炼了目前粮食补贴政策存在的问题,以期为我国粮食补贴政策的制定提供参考。分析表明,我国粮食补贴的形式、对象、范围和目标等在起步阶段（1953-1978年）、探索调整阶段（1979-2003年）和改革发展阶段（2004-2016年）变化明显,补贴资金投入逐年增长且表现出显著的区域差异性;补贴政策逐渐向粮食主产区、经济相对发达的地区倾斜。目前我国粮食补贴政策存在的问题主要体现在补贴效果和目标的差距、补贴对象和范围的核定、补贴结构以及补贴政策的影响力和农户的认知度等方面。研究以期为完善粮食补贴政策制定和提高政策实施效果起到借鉴作用。     

长江中下游粮食主产区耕地利用生态效率区域差异与空间收敛

基于耕地利用生态效率内涵构建其评价指标体系,并运用SBM-Undesirable模型、核密度估计法及空间收敛模型,对长江中下游粮食主产区71个市（州）耕地利用生态效率区域差异及收敛态势定量刻画。结果表明：（1）2007—2018年长江中下游粮食主产区耕地利用生态效率整体水平中等,各粮食主产区效率差异明显,效率损失主要源于投入冗余所带来的投入非效率,其中劳动力投入冗余度最高;（2）时间维度上看,长江中下游粮食主产区整体耕地利用生态效率始终存在两级分化的现象,整体内部差异呈扩大趋势,但逐步趋于稳定,各粮食主产区内部差异演变具有较大分异性;（3）空间维度上看,考虑空间溢出效应的情境下,长江中下游粮食主产区整体存在显著的绝对β收敛,且在科技水平、农户收入水平、灌溉水平及空间溢出效应等因素的共同影响下以1.01%的速度条件收敛,但各粮食主产区收敛态势具有区域差异性。应建立粮食主产区协同机制,因地制宜,分区施策以提升长江中下游粮食主产区耕地利用生态效率水平。     

不同林龄木麻黄人工林生物多样性与土壤养分状况研究

木麻黄（Casuarina equisetifolia）是我国东南沿海海岸防护林骨干树种。本文对广东省茂名市木麻黄防护林开展了不同林龄的种群结构、植物多样性、以及土壤养分特征的研究。结果表明,滨海沙地木麻黄群落在生长过程中有明显的自疏现象,18年林个体数（975株·hm-2）不足3年林个体数一半（2350株·hm-2）,3年至6年龄木麻黄生长最快。调查林地内共有植物27种,其中灌木8种,草本植物18种。随林龄的增长,林下植物种数显著增加,多样性指数、均匀度指数逐步增加,优势度指数下降。林地土壤有机碳、全氮与速效氮供应水平极低;土壤磷供应相对较好,表层有效磷一般高于3.5mg·kg-1。土壤有效养分与植物多样性显著相关,显示养分是植物定居的主要限制因素。结果表明,木麻黄林结构简单,生物多样性低,土壤养分贫乏。     

Lead,cadmium, copper,zinc, iron,and calcium in human hair as a function of gender,age, smoking,and hair dyeing

Hair samples were collected randomly from 110 subjects (55 male and 55 female) ranging in age from (<15–60) years. Each subject was asked to complete a personal questionnaire describing his/her sex, age, general health, smoking, use of hair dyes, occupational area, and living habits. Concentrations of Pb, Cd, Cu, Zn, Fe, and Ca in human hair samples were evaluated using atomic absorption spectrometry. Results indicated that concentrations of Pb, Cd, Cu, and Zn in the hair of smokers were higher than those in the hair of non-smokers, whereas, Fe and Ca concentrations in hair of smokers were lower than those in hair of non-smokers. Moreover, the concentrations of these elements are higher in dyed hair compared with undyed hair.     

藓类-兴安落叶松林木质物残体贮量及组成

以大兴安岭藓类-兴安落叶松林为研究对象,估算木质物残体(WD)的贮量及组成,分析WD随着龄组的动态变化趋势.WD 又可分为粗木质残体(CWD)和细木质残体(FWD),随着对 CWD 研究的不断深入,CWD 的直径划分标准有了改进,美国学者把直径大于10 cm的WD定为CWD,但我国大多学者的研究仍然沿用以往的直径大于2.5 cm的标准,致使研究结果与国际研究无法进行比较.鉴于此,采用新的 CWD划分标准,分析CWD的物种组成、径级结构、腐烂等级及树种组成等特征,揭示CWD密度、体积和生物量贮量及特征随着龄组的变化趋势.结果表明,(1)WD体积和生物量为2.09~151.03 m3·hm-2和1.57~55.11 t·hm-2.从组成上来看,中龄林以倒木和小枝为主(占73.00%),近熟林以枯立木和倒木为主(占96.04%),过熟林以枯立木为主(93.18%).从类型上来看,中龄林均为FWD,近熟林和过熟林中CWD生物量达75%以上.(2)龄组显著影响着藓类-兴安落叶松林WD和CWD的生物量和组成.随着龄组的增加,WD生物量和枯立木比例逐渐增加,倒木和大枝比例减小.CWD 生物量和体积随着龄组的增大而逐渐增加.(3)近熟林中 CWD密度、体积和生物量(217株·hm-2、40.51 m3·hm-2、20.61 t·hm-2)均小于过熟林(258株·hm-2、138.82 m3·hm-2、48.88 t·hm-2).(4)近熟林CWD体积和生物量均以Ⅱ-Ⅲ级腐烂为主(两者之和分别占90.81%和89.01%),过熟林以Ⅲ级腐烂为主(占36.15%和41.23%).(5)过熟林CWD密度、体积和生物量均以10~20 cm为主,且以枯立木居多.     

The challenge of being a young manager: The effects of contingent reward and participative leadership on team‐level turnover depend on leader age

Effective leadership requires a leader claiming as well as team members granting the leadership position. Contingent reward and participative leadership may both facilitate this mutual process. However, these behaviors differ in the degree to which they require a leader to have status and be prototypical. Their effectiveness might thus depend on the status‐related characteristics of the leader. In this respect, we propose that younger leaders, by deviating from the leader prototype in terms of age, lack a natural status cue, which will determine the effectiveness of these two leadership behaviors in shaping turnover. Two pilot studies (N = 113 and 121 individuals) confirm that younger leaders are perceived as less prototypical and to have lower status than older leaders. Examining 83 work teams, we show that leader age differently moderates the effects of contingent reward and participative leadership on time‐lagged team turnover. For younger (compared with older) leaders, contingent reward was effective as illustrated by decreased voluntary turnover and increased involuntary turnover, whereas participative leadership, which was associated with increased voluntary turnover and decreased involuntary turnover, was ineffective. These findings point to the importance of incorporating natural status cues of leaders for understanding the effectiveness of different leadership behaviors. Copyright © 2016 John Wiley & Sons, Ltd.     

The influence of confounding factors on the relationship between muscle contraction level and MF and MPF values of EMG signal: a review

The purpose of this article is to gather results of studies on the relationship between median frequency (MF) and mean power frequency (MPF) and the level of muscle contraction, and to use those results to discuss the differences in the trends according to factors related to measurement technique and subject. Twenty-one studies with 63 cases for upper limb muscles and nine studies with 31 cases for lower limb muscles were analysed. Most results showed an increase in parameters with an increased level of muscle contraction, only some studies showed a decrease. The influence on parameters of the level of muscle contraction and factors such as subjects, type of contraction, muscle length and electrodes was analysed for each muscle. It was concluded that when analysing the influence of different factors on MF and MPF, because those factors interact they should be considered together, not separately.