共查询到20条相似文献,搜索用时 281 毫秒
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王书琦 《林业机械与木工设备》1988,(4)
一、概述所谓综合标准化,就是在进行标准化时,针对不同的标准化对象,以考虑整体最佳效果为主要目的,把所涉及到的全部因素综合起来,用系统工程的方法进行处理。其实质在于把那些能够使标准化对象达到最佳技术水平和质量水平的全部相关要素的系统性和最佳关系反映出来。 相似文献
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Ⅵ.标准化发展趋势 一、综合标准化 综合标准化又称“全面标准化”或“整体标准化”,是指“在进行标准化时,应针对不同的标准对象,以考虑整体最佳效果为主要目标,把所涉及的全部因素综合起来进行系统处理。” 综合标准化的基本特征是系统性,整体 相似文献
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从天然橡胶加工企业生产的角度试分析影响云南天然橡胶企业综合竞争力的原因,并从政策引导、企业定位、强化现场管理、提升产品质量、做好生产成本分析与控制、实现企业管理标准化、制度化等方面阐述了提升云南天然橡胶企业综合竞争力的举措。 相似文献
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《Forest Ecology and Management》1997,95(1):63-77
Fires occur frequently in dry forests of the Inland West. Fire effects vary across the landscape, reflecting topography, elevation, aspect, slope, soils, and vegetation attributes. Patches minimally affected by successive fires may be thought of as ‘refugia’, islands of older forest in a younger forest matrix. Refugia support species absent within the landscape matrix. Our goal was to predict the occurrence of pre-settlement refugia using physiographic and topographic variables.We evaluated 487 plots across a 47000 ha landscape using three criteria to identify historical fire refugia: different structure from surrounding matrix; different fire regime from surrounding matrix; presence of old individuals of fire-intolerant tree species. Several combinations of aspect, elevation, and topography best predicted refugial presence.Less than 20% of the pre-settlement landscape was identified as historical fire refugia. Refugia were not connected except by younger stands within the matrix. Current management goals of increasing amounts and connectivity of old, refugia-like forests for the benefit of species associated with late-successional habitat increase the risk of insect and pathogen outbreaks and catastrophic wildfires. 相似文献
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探索钢板弹簧模糊优化设计的一种新方法,在造价、体积、强度和重量等约束条件下,钢板弹簧的优化设计问题是一个具有多局部极值、非线性及具有整数和实数变量的混合优化问题。本文应用遗传算法和模糊理论,建立了汽车钢板弹簧模糊优化设计的一种新方法。实践证明,自适应遗传算法用于钢板弹簧的设计,效果是十分明显的,并可以在其它类型的机械零件设计中推广应用。 相似文献
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彭荣 《中南林业科技大学学报(自然科学版)》2004,24(4):92-95
不平衡状态下的传递检验TDT是进行连锁分析常用的统计方法之一.统计量Tc,Tm和Tmhet是TDT在多等位基因标识基因座上的推广.为了改进检验的效果,通过给Tmhet的各项以合理的不同的权而得到一个新的检验统计量,并且比较了两者的功效.数字结果都显示这个新的统计量是一个更有效的检验. 相似文献
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南昌市花园城市建设中存在的问题及对策措施 总被引:1,自引:0,他引:1
南昌市花园城市建设中存在绿地发展不平衡、建筑密度过大、绿地结构不合理、缺乏防护林、对绿量与景观质量的综合考虑不够等问题,据此提出了科学规划、加强旧城改造、增强绿地域特色、重视防灾功能等对策措施。 相似文献
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Understory herb communities in the Southern Appalachians are among the highest biodiversity plant communities in North America. In the mid-1990s, a debate began over whether understory herb communities recover to their pre-disturbance states following logging. Studies showing reduced herb-layer diversity in previously logged forests were criticized for not accounting for intersite environmental heterogeneity. More recent studies have addressed environmental heterogeneity, but have neglected long-term recovery by using “mature forests” as young as 80 years old as the benchmark for diversity comparison, even though old growth stands have disturbance return intervals exceeding 500 years. Here we address concerns clouding previous studies of high-diversity Appalachian herb communities and investigate their long-term recovery by comparing paired sites of old growth forest and forest logged 100–150 years ago. We found that species richness and individual abundance is greater in old growth forests than mature forests and that species composition differed significantly between the two. Turnover in species among old growth and mature forests accounted for 11% of the total species richness and was significantly greater than expected. Species turnover at intermediate (5–50 m) and landscape-scales (>10 km) contributed the most towards total species richness. Herb communities in rich cove forests have successional trajectories that exceed 150 years, with important community changes still occurring long after the forest returns to what has been previously termed a “mature” state. To conserve the diverse herb layer, we conclude that mature forest stands are too young to serve as baselines for recovery, landscape-scale preservation of multiple forest stands is needed to maximize species richness, and maintaining 100–150-year logging rotations will likely lead to loss of biodiversity. 相似文献