54 research outputs found

    Research on the Combination Model Based Mid-long Term Forecasting of Power Load

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    电力负荷预测作为电力系统健康发展的重要保证,为供发电制定计划提供参考,为电网的增容、布局建设和投资等提供依据,是电力企业现代化的标志,一直以来都是保证电力系统可靠供电和经济运行的重要课题。随着中国经济的快速发展以及电力发展进入市场化进程,未来电力的发展对负荷预测的准确性、实时性和可靠性提出了更高的要求,提高精确度成为电力负荷预测在新时期将面临的挑战和压力。 电力负荷预测系统是一个非线性动态系统,而传统的数学模型,或者是线性的,或者是非线性的,一般都以静态系统居多。在动态模型的种类中,如神经网络模型,具有自学习、自适应能力,却往往预测时间长、精度不高。随着新时期电力系统结构的日益复杂化,电力...Power load forecasting which provides reference for power generation program, the basis for the increasing capacity, layout of the construction and investment of grid, is an important guarantee for the healthy development of the power system. It is a sign of the power of modern enterprises, and has been the important issue to ensure that the power system is reliable and economical power supply. Wi...学位:工程硕士院系专业:软件学院_工程硕士(软件工程)学号:X201223045

    Research progress in the metabolism of corneal epithelial cells

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    角膜上皮层位于角膜表面,外邻泪膜,内与角膜前弹力层相连。角膜上皮细胞代谢所需营养及氧分主要通过泪膜、房水和角膜缘毛细血管运送。正常的角膜上皮细胞代谢是维持角膜上皮细胞正常增殖与分化状态的关键。角膜上皮细胞代谢异常可导致上皮损伤或变性,是多种角膜疾病的病理基础。本文就近年来关于角膜上皮细胞代谢相关的组织结构、营养来源、细胞增殖分化以及相关疾病的研究进展进行综述。Corneal epithelium is located in the surface layer of the cornea, with tear film outside and Bowman's layer inside.The nutrient and oxygen for the metabolism of corneal epithelial cells is transmitted by tear film, anterior aqueous humor and corneal limbal capillary.Metabolism of the corneal epithelial cells is tightly correlated with its proliferation and differentiation.The abnormal metabolism of corneal epithelial cells can cause epithelial damage or dystrophy, which is the pathological basis of many corneal diseases.This review summarizes recent research progress regarding corneal epithelial cell metabolism related tissue structure, origin of nutrient, cell proliferation and differentiation and diseases related to corneal epithelial cell metabolism.国家重大科学研究计划项目(2013CB967003); 国家自然科学基金面上项目(81270977); 国家卫生和计划生育委员会科研基金项目(WKJ-FJ-26); 福建省高等学校新世纪优秀人才支持计划项目资

    EDI与我国商贸信息化

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    EDI是(ElectronicDatalnterchange)的英文缩写。译为“电 子数据交换”。它是将计算机技术、计算机网络技术、电子通讯技 术应用于商业贸易领域,使标准化的商务数据在EDI系统中传递、 处理。EDI目前已广泛应用于商业贸易组织、银行、海关、运输、 港口,码头、仓储、商检、保险等部门,并将这些部门联在一个 EDI系统之中,使各商贸环节有机地结合,创造出一个高效率的商 贸环境。由于采用EDI商贸方式,可以减少甚至消除贸易过程中的 纸面单证,因而也被形象地称为“无纸贸易”。 EDI最早起源于60年代末的西欧和北美经过30多年的发展,已 逐步进入成熟期。近年来世界...学位:经济学硕士院系专业:经济学院经济研究所_商业经济学号:1992090

    Water stability of biological soil crusts in hilly regions of Loess Plateau,Northwest China

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    &nbsp;采用改进的土壤水稳性团聚体数量测定方法,研究了黄土丘陵区不同组成和生物量的生物结皮层水稳定性.结果表明:生物结皮层的水稳定性与其生物组成有关,苔藓结皮的水稳定性显著高于藻结皮,震荡390次后,苔藓结皮的厚度和质量损失率仅分别是藻结皮损失率的47.3%和40.1%;生物结皮层水稳定性与生物结皮的生物组成有关,60%以上苔藓覆盖度的生物结皮的稳定性最高,质量和厚度损失率分别是藻结皮(无苔藓覆盖)损失率的28.6%和22.7%;生物结皮层水平方向结构水稳定性显著大于垂直方向,震荡390次后,苔藓结皮的面积损失率仅为厚度损失率的6.4%.试验分析证实,生物结皮层是一种水平方向稳定性极强的层状结构体,这一结构特性增强了其抗风蚀和水蚀的能力. </span

    Study on availability of soil phosphorus and plants adaptability

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    研究黄土丘陵区不同植被类型下土壤磷素有效性、植物叶片磷含量及土壤-植物磷素营养关系,以期揭示植被恢复对土壤磷素的影响,明确植物群落对土壤磷素环境的适应性。【方法】以农地为对照,采集了黄土丘陵区125块样地中不同植物(包括草本植物茵陈蒿、长芒草、铁杆蒿及人工林柠条、沙棘、刺槐)的叶片及其生长的土地表层(0~20cm)的土壤样品,测定了土壤全磷、有效磷、pH和叶片磷含量,分析了土壤与植物磷素营养特征以及土壤有效磷与叶片磷含量、土壤pH之间的相关性。【结果】研究区土壤有效磷含量极低(1.54mg/kg),全磷含量较高。不同植被类型下土壤全磷含量差异不显著,但土壤有效磷含量差异显著,土壤有效磷含量由大到小依次为农地&gt;茵陈蒿&gt;沙棘、刺槐、柠条&gt;长芒草、铁杆蒿,土壤pH在不同植被类型样地间差异不明显;不同植被类型叶片磷平均含量为1.43mg/g,其中茵陈蒿和沙棘叶片磷含量较高,与其他植物差异显著(P&lt;0.05);不同植被类型(除沙棘外)样地土壤有效磷与叶片磷含量间相关性不显著。【结论】黄土丘陵区土壤有效磷含量和植物叶片磷含量均低于全球平均水平,且叶片磷含量与土壤有效..】The paper studied the characteristics of soil available phosphorus and leaf phosphorus of typical vegetation communities in loess hilly region.The objective was to explore the effect ofvegetation restoration on soil phosphorus availability,and to understand the suitability of vegetation communities to soil phosphorus condition.【Method】Different plants of the 125plots in Zhifanggou watershedof loess hilly region were selected,including Artemisia capillaris,Stipa bungeana,Artemisia gmelinii,Caragana intermedia,Hippophae rhamnoides,Robinia pseudocacia,taking the crop land as the control.Leaf&nbsp; and surface soil(0-20cm)samples were collected,the soil total P,available P,pH and leaf P content weredetermined.The characteristics of soil and plant P nutrient,the relativity among soil P,soil pH and leaf Pin different vegetation communities were analyzed.【Result】The results showed a great shortage of soil available P content(1.54mg/kg)and a relatively high content of soil total P in the loess hilly region.Significant difference was observed in soil available P content and soil pH among different plants,which wasnot observed in soil total P content.The soil available P in proper order was crop land>Artemisia capillaris>Hippophae rhamnoides,Robinia pseudocacia,Caragana intermedia>Stipa bungeana,Artemisiagmelinii.The average leaf P content was 1.43mg/g and the leaf P content of Artemisia capillaris,Hippophae rhamnoides was significantly higher than other plants(P<0.05).There was no obvious correlation among soil available P content,soil pH and leaf P content in different plants(except Hippophae rhamnoides).【Conclusion】Leaf P content and soil available P content in studied area were lower than the average value in the world.Non-significant correlation was found between P content of soil and plant leaf.Theratio of soil available P content in soil total P content increased with vegetation succession progress,suggesting that soil P status was also enhanced,artificial forest communities appeared to be higher demand ofsoil available P content than herbage communities of natural restoration.Plants P content of specific speciesdid not change as much as soil P.Therefore,the vegetation restoration progress could be acceleratedthrough application of P fertilizer addition in this area.Thus,the plants adaptive mechanism under low Pstress should be attached more attention in future research

    Effects of revegetation on organic carbon storage in deep soils in hilly Loess Plateau region of

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    以黄土丘陵区不同恢复年限的人工刺槐林、人工柠条林和自然撂荒地为对象,以0~100cm(浅层)土壤为对照,研究了不同植被类型下100~400cm(深层)土壤有机碳(SOC)储量的剖面分布特征和累积动态.结果表明:随土壤深度增加,浅层SOC储量显著降低,深层SOC变化趋势不明显,但储量很高,约占0~400cm剖面SOC的60%.80~100cm土层的SOC储量与深层100~200和200~400cm的SOC储量呈显著线性相关,是0~100cm5个土层中与深层SOC储量变化相关性最强的一层,可用以估算深层SOC储量.人工刺槐林、柠条林、撂荒地表层(0~20cm)SOC储量显著高于坡耕地,而深层SOC储量在不同利用类型间差异不显著.随植被恢复年限的增加,深层SOC储量呈上升趋势,人工刺槐林和人工柠条林100~400cmSOC平均累积速率分别为0.14和0.19t&middot;hm-2&middot;a-1,人工柠条林与浅层SOC累积速率相当.在估算黄土丘陵区植被恢复的土壤固碳效应时,应考虑深层土壤有机碳累积量,否则会严重低估植被恢复的土壤固碳效应.</span

    Distribution of light fraction organic carbon under different land use types

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    以黄土丘陵区林地(刺槐和柠条)、撂荒地及坡耕地3种土地利用类型为研究对象,以浅层土壤(0&mdash;100 cm)为对照,采用有机碳密度分组法对不同利用类型深层土壤(100&mdash;400 cm)轻组有机碳含量及其分配比例进行了研究。结果表明,1)3种土地利用类型土壤轻组有机碳含量及其分配比例随土壤深度的增加而显著下降,其含量的变化范围为0.09 1.76 g/kg,分配比例变化范围为4.19%32.24%;各利用类型下亚深层(100&mdash;200 cm)、深层(200&mdash;400 cm)土壤轻组有机碳含量为浅层的12.4%39.8%,分配比例为浅层的28.7%66.2%;随土层深度增加,轻组有机碳含量及其分配比例的降幅在不同土地利用类型下表现为刺槐林地&gt;撂荒地&gt;柠条林地&gt;坡耕地;2)各土地利用类型下同一土层轻组有机碳含量及其分配比例不同,浅层、亚深层和深层土壤轻组有机碳含量及其分配比例表现为林地&gt;撂荒地&gt;坡耕地。3)退耕还林还草增加了浅层土壤轻组有机碳含量及其分配比例,却降低了亚深层、深层土壤轻组有机碳含量及其分配比例,即与浅层土壤相比,植被恢复相对增加了深层土壤有机碳的稳定性。 更多还原Taking the Robinia pseudoacacia woodlands,Caragana korshinskii shrublands,abandoned croplands,and slope croplands in hilly regions of the Loess Plateau as study objects,we investigated the contents anddistribution ratios of soil light fraction organic carbon ( LFOC) in the deep soil layer( 100-400 cm) under differentland use types by using the method of relative density fractionation with the shallow soil layer( 0-100 cm) as thecontrol. The results show that there are significantly declining trends in the content and distribution ratio of soil lightfraction organic carbon along with the increase of soil depth under the studied land use types. The contents of soillight fraction organic carbon range from 0. 09 to 1. 76 g /kg,while the distribution ratios of soil light fraction organiccarbon range from 4. 19% to 32. 24%. Under the three land use types,the contents and distribution ratios of soillight fraction organic carbon in the sub-deep soil( 100-200 cm) and deep soil( 200-400 cm) of that in the shallowlayer( 0&mdash;100 cm) range from 12. 4% to 39. 8%,28. 7% to 66. 2%,respectively. The declining rates of the soil&nbsp; light fraction organic carbon contents and distribution ratios are Robinia pseudoacacia woodlands > abandonedcroplands > Caragana korshinskii shrublands > slope croplands. The contents and distribution ratios of soil lightfraction organic carbon in the same soil layer among the three land use types are different. The contents anddistribution ratios of soil light fraction organic carbon both are forestlands > abandoned croplands > slope lands inthese three layers. Both the contents and distribution ratios of soil light fraction organic carbon are increased afterthe implementation of the Grain for Green project,while those in the sub-deep and deep soils of those in the shallowlayer are reduced. Compared with the shallow soil layer,the stability of deep soil organic carbon is enhancedrespectively in the process of revegetation

    Organizational learning capacity, new product development speed and organizational performance: the moderate effect of demand uncertainty

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    企业面临着激烈竞争和日益动荡的经营环境,创新效率逐渐成为其保持竞争优势的重要因素。通过调查研究方法,以福建101家制造企业为研究对象,在检验组织学习能力、新产品开发速度与组织绩效之间关系的基础上,分析市场需求不确定性对上述关系的调节作用。研究结果表明:新产品开发速度对组织绩效具有正向影响,并在组织学习与组织绩效的关系中起到中介作用;此外,市场需求不确定性正向调节新产品开发速度与组织绩效之间的关系,即市场需求不确定性越高,新产品开发速度对组织绩效的正向影响就越强烈。This article identifies the relationships between the organizational learning capacity, new product development speed and organizational performance, as well as considering the effect of demand uncertainty. The empirical results based on the data from 101 shoes and clothing enterprises in Fujian concludes that: organizational learning capacity enhances the organizational performance through the mediate effect of the new product development speed. But the demand uncertainty positively moderates the positive relationship between NPDS and organizational performance. Finally, there are also some limitations and expectations should be considered in the future.国家自然科学基金项目“我国服务型组织中主动性氛围的内涵、形成机制与影响后果”(71572164);福建省中青年教师教育科研项目“营销3.0时代福建省消费者信任重塑与品牌提升问题研究”(JA12007S);贵州省教育厅高校人文社会科学研究基地项目“贵州喀斯特地区旅游产业和互联网金融产业融合问题研究”(JD2014047)

    A New Particle Swarm Optimization Approach to the Inertia Parameters Identification of Onorbit Space Robot

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    提出了针对一类多自由度空间机器人卫星惯性参数在轨辨识的一种粒子群(PSO)优化新算法。通过粒子邻域限定的多样性保持、低效粒子随机重置和粒子误差的序列性评价,得到了比常规方法更好的结果,且具有无附加燃料消耗、线动量测量和特定的机器人路径规划等便利性优点。仿真算例表明,该改进方法具有较高的准确性与效率

    Ti同位素分析方法及应用研究进展

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