基于ADAMS/Cable的烟草打顶机钢丝绳升降系统的动力学仿真

针对ADAMS传统方法难以高效、精确地进行大变形柔性体钢丝绳的建模与仿真问题,提出了利用ADAMS Machinery/Cable模块创建烟草打顶机打顶装置、驱动液压缸、升降运动导轨、钢丝绳、滑轮的刚柔耦合多体系统动力学模型的方法,并对其虚拟样机模型进行了动力学仿真分析。结果表明：利用Cable建模向导能够快速、精确地创建钢丝绳系统,仿真速度更加迅速,为深入分析烟草打顶机打顶升降装置的振动稳定性、运行安全性及疲劳特性等奠定了基础,也为各种钢丝绳吊装系统的建模提供了一种全新的思路。     

板栗象甲和蛾类的化学防治效果

为了解农民喷施化学药剂对板栗主要虫害的防治效果,2009年5—10月,在安徽省金寨县油坊店乡选择20棵板栗母树,其中10棵喷施化学药剂,10棵不喷施化学药剂,每7d收集落果,对虫害情况进行调查,最终通过产量调查评估喷施化学药剂对板栗主要虫害的防治效果。结果表明:喷施化学药剂对剪枝象和栗实象有明显的防治效果;喷施化学药剂,对雪片象和蛾类无明显效用。由此可见,喷施化学药剂对部分板栗虫害有较为明显的防治作用,有利于提高板栗产量和单粒质量,但应根据不同虫害的发生规律及特点,适当、适时、适量地使用化学药剂。     

液压锯木机的研制

介绍了所设计液压锯木机的结构与原理,对不同工况下液压系统的控制进行了分析.该机能更好地适应各种工况的作业要求,降低了工人的劳动强度,提高了安全性和工作效率.     

深耕免灌机改型设计

在引进意大利瓦勒拉尼系统深耕免灌机的基础上,对其整机的核心技术传动部分、液压部分、犁体部分进行了改型设计,应用电控、液压传感装置,替代了原有的链条式塔轮机构,实现了4个不同规格位置的间距鱼鳞坑开沟作业,解决了引进设备在我国干旱、半干旱地区深耕整地开沟的作业问题。新研制改型的深耕免灌机即鱼鳞坑开沟犁,其机型结构中机械、电控、液压一体化水平高、测距精确、结构简单、可靠性高、成本低廉,具有很高的推广价值。     

试制成功液压捣固机

我局森林铁路共300多公里,承担全局生产运输任务。线路维修作业,人工打镐,劳动强度大,质量低,成为森铁维修作业主要矛盾。为了解决这个矛盾,森铁组成有领导干部、工人和技术人员三结合领导小组,去锦州、北京、太原铁路局参观学习。通过学习分析对比,认为液压捣固机比电动捣固机进了一步,适合森铁维修作业条件。因此我们确定仿制交通部DH——3型小液压捣固机作为我森铁第一代捣固机。经过三个月的努力,于74年11月份试制成功。     

J—80型拖拉机液压转向器的故障诊断：故障树分析方法的应用

J-80型拖拉机是以集材为主,并能综合利用的四轮驱动80马力拖拉机。它是我国林区生产中使用的主要集材设备之一,其液压系统可实现折腰转向和控制排障器、搭载板起落及绞盘机卷筒制动等。由于采用了液压系统,大大地改善了该机的性能,提高了集材作业的生产效率。但是,由于林区作业条件恶劣,各使用单位缺乏使用、     

几种生物农药防治烟草花叶病的药效研究

生物农药在烟草花叶病的防治中具有重要的地位和广阔的应用前景.通过7种生物药剂的田间小范围示范性试验.结果表明,保健驱蚜剂用清水稀释5倍进行叶面喷施对花叶病的防效最好,平均达49.29%,药效也持久,今后可以通过加大其药量或浓度等进一步的试验研究,最终确立其最佳药量或浓度.此外,于苗期100倍液,大田期300倍液进行叶面喷施的HN3S,平均防效达26.03%,也有一定的研究和应用价值.     

多层压机液压伺服系统性能仿真分析

分析多层压机液压伺服系统组成及加压过程,以多层压机液压伺服系统为研究对象,根据多层压机相关特性参数分析系统负载特性,建立以压力为输出的多层热压液压伺服系统的数学模型;应用MATLAB/Simulink对液压伺服系统进行仿真,得到系统伯德图和阶跃响应曲线,根据伯德图和阶跃响应曲线对液压伺服系统性能(稳定性、快速性及准确性)进行分析,结果表明系统稳定性良好;针对液压伺服系统性能(快速性和准确性)存在的缺陷进行了改进设计,加入PID控制器环节,改善了液压伺服系统的响应速度和准确性。     

瑞典木材装卸液压起重臂简介

一、液压起重臂的发展概况瑞典木材装卸作业中,广泛使用液压起重臂,在三十年代木材是靠人力装车。四十年代末及五十年代初期,开始利用简易绞盘机将木材提升起来,直到五十年代末期才开始着手研究设计新型的液压起重     

不同药剂防治烟草黑胫病效果研究及综合防治对策

为了筛选出防治烟草黑胫病的有效药剂,选取了5种防治烟草黑胫病的药剂并在枣阳地区进行了防效试验。结果表明：参试的5种药剂品种中,对烟草黑胫病的防治效果以枯草芽孢杆菌最好,其次是40%烯酰吗啉、58%甲霜灵锰锌可湿性粉剂,这3种药剂可作为枣阳烟区防治烟草黑胫病的首选药剂。针对烟草黑胫病的综合防治,可以从选择适宜的抗病品种、保健栽培、生物防治以及化学药剂交叉使用等方面开展,以实现烟叶生产的可持续健康发展。     

Browsing Damage on Pine (Pinus sylvestris and P. contorta) by a migrating moose (Alces alces) Population in Winter: Relation to Habitat Composition and Road Barriers

In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads.     

Effects of Root Freezing on the Physiology and Growth of Picea glauca,Picea mariana and Pinus banksiana Seedlings Under Different Soil Moisture Regimes

The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage.     

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.     

Growth and Terminal Bud Formation in Picea abies Seedlings Grown with Alternating Diurnal Temperature and Different Light Qualities

The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions.     

CAD与建筑设计的关系

本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。     

Natural Regeneration in Clear-cuts: Effects of Scarification,Slash Removal and Clear-cut Age

The effects of soil scarification (mounding), slash removal and clear-cut age on the natural regeneration in clear-cuts was evaluated using data from four sites in southern Sweden. The treatments were carried out during a good seed and establishment year for birch ( Betula pubescens Ehrh. and B. pendula Roth). Scarification had the strongest positive effect on the density of naturally regenerated seedlings, especially in birch, but also in pine ( Pinus sylvestris L.) and spruce [ Picea abies (L.) Karst]. Slash removal had a positive effect on birch density. No statistically significant effect of clear-cut age was found. In addition, no statistically significant interactions between clear-cut age and scarification or slash removal were found. The ingrowth of field vegetation was the fastest in areas that were not scarified, less rapid in areas scarified on old clear-cuts, and the slowest after scarification in fresh clear-cuts. In conclusion, it may be possible to control the density of birch during a good establishment year for birch. If birch is desired, the best combination of treatments is to remove the slash and scarify; otherwise, these treatments should be avoided.     

Risk Perception Among Non-industrial Private Forest Owners

Based on an enquiry, risk perception among non-industrial private forest owners is described in relation to climate change and forestry hazards. Of the respondents, 11% took action to remedy the effects of climate change. Out of a given set, hazards were ranked according to each respondent's experience of recent substantial financial loss to the estate and in relation to his or her willingness to make investments aimed at risk reduction. For each hazard, the respondent assessed the risk in four classes ranging from very high to negligible risk. Six hazards were considered most problematic in all three aspects: browsing damage, falling timber prices, damage by wind, spruce bark beetle, root rot and pine weevil. A majority of the respondents claimed to take action to reduce the risk associated with at least one hazard, while 35% did not know whether they did. Excluding climate change, the need for decision support was the largest in relation to damage by wind owing to a combination of perceived high risk and a high level of ignorance in relation to whether risk-reducing measures were taken.     

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.     

Pasture production and tree growth in a young pine plantation fertilized with inorganic fertilizers and milk sewage in northwestern Spain

The use of organic waste materials such as milk sewage as an organic fertilizer could have the dual advantages of organic-waste disposal and reduced dependence on inorganic fertilizers. The effects of fertilization with (1) conventional mineral fertilization, (2) milk sewage sludge at 40 kg N ha⁻¹ target rate and (3) no fertilization on pasture production and tree growth were examined in an experiment consisting of two pasture mixtures under a one-year-old Pinus radiata plantation with a density of 2500 trees ha⁻¹. The two pasture mixtures were: (1) Dactylis glomerata L. var. saborto (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹); (2) Lolium perenne L. var. Tove (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹). The experiment began in the spring of 1995 using a randomized block design with three replicates in Castro Riberas de Lea (Lugo, Galicia, north-western Spain). Plot size was 12 × 8 m², with a 1 m buffer strip between plots. Two-year data showed that fertilization with either material had a positive effect on pasture production, with no significant difference between the two fertilization treatments. Tree growth in the milk sewage sludge plot was significantly higher than in the control plots. Inorganic fertilization increased pasture production, but affected tree growth negatively. The results show that milk sewage sludge could be used as a fertilizer in silvo-pastoral systems. This revised version was published online in June 2006 with corrections to the Cover Date.