徐州住宅不同供暖方式下热环境与舒适性调查分析

指出了目前市场上存在有多种供暖方式,不同的供暖方式,其室内热环境及舒适性也不尽相同。为比较不同供暖方式对室内热环境与用户的热舒适性的影响,选取徐州地区不同供暖方式的典型住宅小区,采用调查问卷与跟踪实测两种方法进行了调研,并对调研结果进行了统计与分析,根据分析结果提出了具有参考价值的建议。     

地暖供热的发展空间和应用

随着社会的发展及人们对节能低碳生活的重视，大量的新技术在越来越多的行业应用起来，供暖行业也不例外。在供暖形式上人们改变了传统的散热器供暖方式，而是采用地暖供热。地暖供热：即将加热管安装在地板以下，用热媒不高于60℃的热水使地板循环加热。以辐射和对流的方式通过地面向室内供暖的供热方式。该文从地暖供热的优势、应用发展前景及使用时的注意事项几方面进行了综合论述。     

2017～2020年采暖期沈阳市空气质量变化研究

由于在以往空气质量分析中,经济活动连续性和持续性使得无法准确估算供暖行业对大气质量的直接影响。而2019～2020年供暖期的城市社会经济活动受到抑制,这为科学评估供暖企业排放影响空气质量提供了机会。为此,对比分析了2017～2020年沈阳市冬季供暖期间的气象因子、空气质量指数和主要污染物浓度指标,明确了供暖行业、社会生产和交通运输对空气质量污染物排放量的贡献。结果表明:2019～2020年集中供暖期沈阳市大气环境质量比往年有明显改善,且空气质量主要受地面污染物总排放量的调控,与气象因子无显著相关性。供暖企业污染物排放量占冬季大气环境污染物总排放量的60%～80%,且与供热面积正相关;而社会生产和交通运输对空气污染物总量的贡献占比20%～40%。因此,集中供暖污染物排放仍是沈阳市冬季空气污染物的主要来源,提出了从供暖行业视角进行节能减排仍是提高和改善冬季空气质量的重要措施和手段。     

单管系统在户式采暖中的应用

根据现在户式小型采暖炉供暖的特点,并结合供暖工程和应用实例对比,对单管水平系统加跨越管及散热器如何合理分布进行了分析,阐明了选择合理的布置方式可节约投资、并能满足供暖要求的设计理念。     

浅谈地面辐射供暖中几个应注意的问题

近年来,一种高效节能的供暖方式——地面辐射供暖(地采暖)逐渐为人们所接受,特别是在新建的高档住宅楼中,地面辐射供暖得到广泛的采用。地面辐射供暖的热源可采用热水加热的铝塑盘管、地热电缆、地电热板、地电热膜等。使用的地面材料有木地板、地毯、地砖、石材、塑料地板等。但最常用的是以低温热水为热源,木地板为地面材料的低温热水地板辐射供热系统。本文集中讨论这种地采暖系统中的一些问题。     

供热调节方式分析

在我国北方,特别是地处严寒地带的黑龙江省,每年的供暖期长达半年之久,每年用于建筑供暖的燃料、水、电等能源消耗是相当可观的,如何尽量降低建筑供暖能耗,应引起有关部门和能源工作者的注意.本文仅对供暖系统的合理调节及节能的影响作一些初步研究与探讨.     

浅析地板辐射供暖

地板辐射供暖是一个新课题。但在北京、呼和浩特、大连等地区已从试点进入实施阶段。有关地板辐射供暖规范、规程、标准已陆续制定、发布。     

分户计量供暖系统形式的探讨

本文通过对散热器分户供暖几种系统形式的分析，阐明了在分户供暖设计时宜采用双管水平同程式系统形式。     

某厂房低环温空气源热泵系统供暖运行效果分析

为解决甘肃慧联信息科技发展有限责任公司厂房离市区集中供暖达10km以上、导致采用市政集中供暖成本过高的问题,采用低环温空气源热泵系统为厂房及办公楼提供热源。对整个厂区供暖系统进行了设计,后对系统运行的具体参数进行了分析,结果表明:采用体积热负荷对建筑进行热负荷的计算体积热指标平均值比设计选型时选择的高5.4%,低环温空气源热泵属于高效、清洁的供暖热源。     

地热实木地板点滴

在地热的地面上铺装实木地板,是芦苇席和其它任何材料所不能比的。这种科学的供暖方式已在欧美普遍兴起,成为人们追求的热点。     

Canopy management possibilities for arboreal Leucaena in mixed sorghum and livestock small farm production systems in semi-arid India

A major problem for small farmers in the semi-arid tropics is the chronic shortage of fodder for draft animals. Leucaena leucocephala has improved productivity in many places in India and in various cropping systems, usually as either a pure crop or in a hedgerow alley-cropping configuration. Mixed cropping with arboreal forms is seldom seen. For off-season fodder production, hedgerows have the disadvantage of being open to unmanaged browsing when unfenced (as is usual). Arboreal forms are generally far less vulnerable. In this paper, the components of production of sorghum and arboreal Leucaena are measured under different intensities of canopy lopping. The most productive management system of those examined was pollarding of the Leucaena at the time of under-sowing with sorghum. In a year with less than 50% of average seasonal rainfall, this system gave a yield of 4.6 tonnes/ha/yr fresh wt fodder and 3.8 tonnes/ha/yr dry wt. of fuel harvests, while increasing the standing crop of wood by 1.8 t/ha/yr and retaining a yield of sorghum grain equivalent to 46% of pure sorghum cropping; the LER of this system was 1.35. Cash values of the alternative management systems were estimated, including the discounted Net Present Value of the standing crop of timber. Maximum value was attained with unlopped pure crop Leucaena followed by pollarded Leucaena with sorghum; pure crop sorghum achieved a lower value. These results demonstrate both the high productivity of Leucaena/sorghum based systems, and the stability of production even in poor rainfall conditions. Pollarding transferred the high future value of Leucaena timber to the present value of sorghum grain and fuelwood.     

Interactions in decomposition and N mineralization between tropical legume residue components

In situ produced plant residues contain a mixture of different plant components of varying quality. To assess synergistic or antagonistic interactions occurring during the decomposition and mineralization of such mixtures, individual plant parts (stems, leaves, leaf litter and roots) or the mixture of stems, leaves and leaf litter of the agroforestry species pigeonpea (Cajanus cajan) or of crop residues of peanut (Arachis hypogaea) or of the weed hairy indigo (Indigofera hirsuta) were incubated in pots for 19 weeks. Periodically, remaining plant residues were sieved out (>2 mm), weighed and N content as well as soil mineral N determined. Above- and below-ground residues of peanut decomposed fastest and showed the largest N release in agreement with their high N concentration and low-acid detergent fibre (ADF) : N ratio. Hairy indigo was hypothesized to be of lower quality than pigeonpea because of its high-polyphenol content. However, it decomposed faster than pigeonpea, largely because of the higher N and lower lignin concentration of its components. Ranking of individual plant components for N mineralization resulted in the following pattern, leaves > leaf litter > roots > stems. In mixtures of the different plant components a similar species order in decomposition was obtained, e.g. peanut > hairy indigo > pigeonpea. The amount of N released from the mixture was dominated by stem material that comprised 46–61% of the mixture. The interactions in mixtures were relatively small for peanut (generally high-quality components) as well as for pigeonpea (low proportion of high-quality components, i.e. N rich leaf material). However, a positive interaction occurred during later stages of N mineralization in the mixture of hairy indigo as it had a significant proportion of N rich components and absence of highly reactive polyphenols. Thus, for plants with low to intermediate chemical quality attributes, manipulating plant composition (e.g. by varying harvest age, affecting stem and leaf proportions) will be important to obtain significant interactions during decomposition when its components are mixed.     

天牛体内纤维素酶研究进展

文章综述近年来国内外有关天牛体内纤维素酶的研究进展,主要包括:天牛体内纤维素酶的来源、不同天牛种类纤维素酶的性质、纤维素酶抑制剂、纤维素酶同工酶、纤维素酶基因以及天牛体内纤维素酶活性变化与寄主的关系,并展望了未来的研究方向。     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland.     

Modeling spatial variability and pattern of rust and brown eye spot in coffee agroecosystem

The advent of Precision Agriculture has made possible the analysis of complex spatial patterns of plant disease epidemiology considering statements of integrated disease management. The objective of this work was to use geostatistics, statistics and geographical information systems to characterize the structure and magnitude of spatial dependency of rust (Hemileia vastatrix) and brown eye spot (Cercospora coffeicola) incidence and severity in coffee agroecosystem cultivated with Catuai Vermelho IAC-99 (Coffea arabica L.). Evaluations of incidence and severity of rust and brown eye spot were accomplished at 67 georeferenced points arranged in 6.6202 ha of coffee crop, in the years of 2005, 2006 and 2007. Exponential models of covariance enabled the characterization of the magnitude and structure of rust and brown eye spot spatial variability in the evaluated dates. Ordinary block kriging presented satisfactory performance to map rust and brown eye spot outbreaks based on kriging error coefficients. Kriged maps enabled the visualization of intensity of rust and brown eye spot in each evaluation date. Assessments of incidence and severity presented highly statistical correlation based on linear regression models, also confirmed by the spatial variability of kriging maps. Kriging maps of rust and brown eye spot enabled to observe that intensity of disease was dispersed in foci patterns along the coffee plantation, indicating that the current strategy of disease control based in total area may be replaced by site specific disease management, with less environmental impact and sustainability of coffee crop, according to statements of integrated disease management and precision agriculture.     

Nutrient cycling and growth in forest ecosystems of south western Australia: Relevance to agricultural landscapes

Nutrient and hydrologic cycles in harvested native forests in southern Australia are largely balanced. For example, we have little or no evidence of any decline in nutrient capital or availability in harvested forests. Short-term and small-scale reductions in evapotranspiration due to loss of leaf area after harvesting are adequately balanced at the landscape scale by large areas of regenerating or older-age forest. In contrast, agricultural systems on similar soils are a) dependent on large inputs of fertilisers to maintain growth and b) frequently subject to increasing salinity and waterlogging or other forms of degradation. The large-scale replacement of long-lived communities of perennial and often deep- rooting native species with annual crops or other communities of shallow-rooting species might be better managed within the framework of knowledge developed from studies of native plant communities. However, application of such a mimic concept to systems of low natural productivity is limited when agricultural systems require continued high productivity. Nonetheless, the mimic concept may help in developing sustainable management of agriculture on marginal lands, and contribute to the nutritional resilience of agroecosystems. Relevant characteristics for mimic agroecosystems in south western Australia include: high species diversity, diversity of rooting attributes, utilisation of different forms of nutrients (especially of N and P) in space and time, and the promotion of practices which increase soil organic matter content. This revised version was published online in June 2006 with corrections to the Cover Date.     

Native woody species regeneration in exotic tree plantations at Munessa-Shashemene Forest,southern Ethiopia

Regeneration of native woody species was studied in the plantations and the adjacent natural forest at Munessa-Shashemene Forest Project Area, Ethiopia. The aim of the study was to test the hypothesis that tree plantations foster regeneration of native woody species. A total of 60 plots, having 10 × 10 m area each, were studied in monoculture plantations of 4 exotic species (Cupressus lusitanica, Eucalyptus globulus, E. saligna, Pinus patula) and an adjacent natural forest. Ages of the plantations ranged between 9 and 28 years. Soil seed bank analysis was also undertaken from soil samples collected in each of the 60 plots to examine the similarity between the soil seed flora and aboveground vegetation. A total of 56 naturally regenerated woody species were recorded beneath all plantation stands with densities ranging between 2300 and 18650 individuals / ha in different stands. There was a significant difference among plantation stands with regard to understorey density (standard deviation: 4836 ± 1341). Vegetation diversity was assessed through analyses of floristic composition, species richness and abundance. Generally, seedling populations were the most abundant components of the regeneration in most of the plantation stands, forming 68 % of the total regeneration count in all stands. A total of 77 plant species represented by 44 herbs, 13 woody species, 8 grasses and 12 unidentified species were recorded in the soil seed bank from all stands. Similarity between the soil seed bank and aboveground flora was very low implying that the role of soil seed banks is negligible rather dispersal plays an important role in the process of regeneration. These results support the concept that forest plantations can foster the regeneration of native woody species, thereby increasing biological diversity, provided that there are seed sources in the vicinity of the plantations.     

Trees and shrubs as sources of fodder in Australia

Experience with browse plants in Australia is briefly reviewed in terms of their forage value to animals, their economic value to the landholder and their ecological contribution to landscape stability. Of the cultivated species only two have achieved any degree of commercial acceptance (Leucaena leucocephala and Chamaecytisus palmensis). Both of these are of sufficiently high forage value to be used as the sole source of feed during seasonal periods of nutritional shortage. Both are also leguminous shrubs that establish readily from seed. It is suggested that a limitation in their present use is the reliance on stands of single species which leaves these grazing systems vulnerable to disease and insects. Grazing systems so far developed for high production and persistence of cultivated species involve short periods of intense grazing followed by long periods of recovery. Similar management may be necessary in the arid and semi-arid rangelands where palatable browse species are in decline.     

Measurement of Green Plank Shape for Prediction and Elimination of Compression Wood

The objective of this study was to predict the amount and the distribution of compression wood (CW) within a Norway spruce [ Picea abies (L.) Karst.] plank based on green plank curvature. The findings indicated a possibility of predicting the longitudinal distribution of CW from the green plank curvature. Areas free from CW showed a typical concave shape in relation to the centre of the log, while CW was present when a convex shape was shown. The larger the magnitude of convex curvature, the higher the concentrations of CW that could be found, and a larger fraction of dried planks was rejected due to excessive warp. This study also determined what information can be used to eliminate areas of high concentrations of CW by cutting and how cutting affects the grading results with respect to warp. Over 50% of the plank length showing a high concentration of CW (>30% of the cross-cut volume) was successfully cut off. Cutting strategies based on predicted CW concentrations resulted in a 10-40% increase in accepted plank length.     

闽南山地木荷林套种南方红豆杉的试验

为了解南方红豆杉在闽南山地生长所需的环境条件,开展了木荷林下套种南方红豆杉的试验研究,结果表明,在较高郁闭度的木荷林中套种南方红豆杉,随木荷林郁闭度的增大,南方红豆杉的树高、地径和生物量降低,叶绿素含量减少,养分含量下降。郁闭度为0.5的木荷林套种南方红豆杉,其生产力最高,叶绿素含量和养分含量均最大。