白桦粒度对其热解特性的影响

以白为生物质原料，将原料分为:0.2-0.5mm;0.5-0.8mm;0.8-1.2mm三个粒度等级，采用热重法（TG）和微商热重法（DTG），分别在升温速率为10、20、40、60℃/min四种条件下进行热解实验和热解特性研究。得出结论：在相同的升温速率条件下，白桦颗粒尺寸增大，平均热解速率趋于减小，其减小的程度与升温速率有关；高升温速率时，白桦颗粒尺寸增大，平均热解速率下的程度，大小低升温速率时的平均热解速率，颗粒尺寸增长，最大失重速度点温度Tp趋于增大，高升温速率热解时，应尽量减小白桦颗粒尺寸。     

热处理木材及其在欧洲的发展

有效的利用木材资源是一个令人们关注的重要课题,尤其是在森林覆盖率低的国家。由于环保意识的增强,人们对木材的功能性改良越来越多地侧重于采用物理处理方法。在这样的背景下,木材热处理在许多发达国家迅速的蓬勃发展起来,尤其是在欧洲。欧洲许多国家的科研机构和生产企业都进行了大量的研究,一些大的木材热处理厂也相继建立。本文回顾了木材热处理技术的发展历程,列举了热处理木材在以荷兰、德国、法国和芬兰为代表的欧洲国家中的工业化现状,总结了热处理材性能改善的原因、环境特性以及性能和用途。图2参26。     

玉米果穗生长特征的量纲分析

以两个玉米品种为材料,设置肥密顺、逆境对比试验,应用量纲分析原理筛选反映玉米穗与粒生长特征的变量及其数量关系式,探索量纲分析在玉米花后果穗和穗粒生长特征研究中的应用价值。重量、密度、容(体)积和相对生长率均是果穗和穗粒的重要生长特征。授粉后,果穗密度最小值、最大值分别为0.072和0.56 g/cm3,穗粒密度为0.061和0.63 g/cm3,它们的时间动态均符合y=a+b×cos(ct+d)。果穗密度、穗粒密度、果穗重量相对生长率、穗粒重量相对生长率、果穗体积相对生长率和穗粒容积相对生长率都具有逆境的稳定性,授粉至成熟的均值分别为0.273 g/cm3、0.285 g/cm3、0.10、0.11、0.076和0.076。果穗体积相对生长率和穗粒容积相对生长率具有基因型的稳定性。同一器官的重量相对生长率和容(体)积相对生长率之间关系符合y=ax/(b+x)。量纲分析有助于解析玉米花后果穗和穗粒生长。     

基于介数中心性的板式定制家具零件尺寸参数传递研究

针对板式定制家具个性化设计不断变化等现状,以提高设计效率为目的,运用介数中心性分析各板件在变型设计尺寸参数传递中的重要程度,确定变型参数的传递路径,最终实现板式定制家具变型设计。运用实例验证该方法在板式定制家具中应用的可行性,为板式定制家具的变型设计提供新思路。     

Application of Changing Dimension and Classifying Power Management to Large-scale MIS

While large-scale MIS is being developed, what relation schema and power management system to set up greatly influences its initial development and later use. First, to solve the setup of relation schema concerning constant change in the attribute of an entity, a changing dimension based on the relational theory in tradition has been used for the setup of relation schema with a wide adaptability; second, to achieve effective power management where there are different standards for business classification on account of too many users and frequent alteration, a classifying power management system has been adopted for the realization of classified self-management model, making the whole system compact and flexible.     

基于因次分析的盐田铺膜机动力参数研究

盐田铺膜机采用旋耕机逆转工作，一次完成切土，升土，抛土等工序，与一般旋耕机的工作方式不同，难以直接应用现有的研究结果分析其动力损耗，因此，根据土壤的特性，采用流体力学中分析流体状态的因次分析方法，由泊金汉π定理得出通用模型的准数方程并线性化，测出样机在预定工况下工作时各主要参灵敏，用最小二乘法估计各系数，并在实验值范围内分析各参数对动力损耗有无显著影响，对盐田铺膜机的改进及优化提供了基本参考依据。     

毛坯尺寸标注基准的选择

根据毛坯尺寸的作用 ,应用工艺尺寸式方法推导出在毛坯尺寸设计过程中应遵循的法则 ,以减小各加工面的粗加工余量公差及提高加工面相对于非加工面的尺寸和位置精度 ,通过实际验证 ,证明基于这种法则的毛坯设计对提高产品质量、降低材料消耗有重要意义     

Effects of salinity on the nail-holding power of dimension lumber used in light-frame wood building

We studied the effect of salinity on nail-hold-ing power in wood construction. In saline solution, the holding power of nails was less than in purified water. With the increase of salt concentration, t...     

库布齐沙地滴灌人工林土壤水分运移及其与土壤分形特征的关系

【目的】探究库布齐沙地人工林滴灌下土壤水分运移规律以及其与土壤分形特征的关系,以期为人工林滴灌策略制定提供参考。【方法】以典型人工林为研究对象,基于激光粒度衍射法测得土壤粒径分布并计算单重及多重分形维数,通过大田试验明确灌水及水分再分布过程湿润锋动态变化规律,并采用通径和冗余分析等手段探究湿润锋运移与分形特征的联系。【结果】1)库布齐沙地滴灌人工林湿润锋水平及垂向运移可分别用对数函数(R2=0.941~0.990)和幂函数(R2=0.958~0.996)描述；2)砂粒含量高于70%、黏粒低于2.5%土壤条件下,利用粉粒、黏粒含量构建的多元回归模型能较好地计算停灌后二维水分运移距离(R²=0.839~1.0),但对停灌前适用性较差(R2=0.243~0.403)；3)单重分形维数D和信息维数D1、信息维数/容量维数D1/D0、关联维数D2均与砂粉比呈负相关,而滴灌形成的湿润体体积与砂粉比正相关,且D较D0、D1、D1/D0、D2更能解释土壤砂粉比差异对湿润锋运移的影响。【结论】滴灌下人工林水分运移满足函数定量关系,砂粒占比高于70%且黏粒低于2.5%时,土壤质地越粗则湿润体体积越大,可在灌溉策略制定时进行土壤粒径分析,节约决策成本。与库布齐沙地相似环境条件下,滴灌时长6h流量3.0L.h-1时,速生杨和榆树林在停灌后48h需启动下次灌溉,沙柳和旱柳林则不需要。     

How perceived sensory dimensions of urban green spaces affect cultural ecosystem benefits: A study on Haizhu Wetland Park,China

Research exploring the relationship between human well-being and ecosystem functions by assessing cultural ecosystem benefits (CEBs) is a crucial and emerging field. However, quantifying CEB is challenging due to the lack of a uniform measurement scale. In addition, it is crucial to understand the factors that influence CEBs to enhance ecosystem functions and contribute to human well-being. While physical landscape features have been investigated, there is limited evidence supporting the link between perception-based landscape features and CEBs. Therefore, this study aimed to develop a CEBs measurement scale and investigate the impact of perceived sensory dimensions (PSDs) of urban green spaces (UGSs) on CEBs. We conducted a Public Participation GIS-survey (PPGIS) at Guangzhou National Haizhu Wetland Park. 1473 participants took part in our study and evaluated the CEBs provided by urban green spaces (UGSs). Using SPSS statistics and ArcMap tools, we found that PSDs of UGSs are significantly associated with CEB. Additionally, we confirmed that different levels within a PSD influence the levels of CEBs gained from UGSs. Our results indicate that creating serene, open, and natural UGSs is more effective than incorporating numerous cultural elements. In conclusion, this study introduces PSDs into the framework of CEB, which landscape architects can use to shape the specific environmental characteristics of UGSs and provide the CEBs required to support the well-being of urban populations.