轮式与三角履带式集材机的爬坡性能比较

我国东北林区经过多年采伐后,现森林资源主要分布在坡度15°以上地区,这对集材机的爬坡性能要求大幅增加.通过对集材机爬坡过程进行受力分析,得到集材机牵引力、最大爬坡度、爬坡速度和能耗的表达式.对三角履带式集材机ZLY-930E和轮式集材机ZLY-925D的参数进行爬坡度、爬坡速度和能耗的计算和分析,结果表明:在多种集材路面上,三角履带式集材机都能保证空载最大爬坡度达到20°以上,而爬坡速度较低,一般不超过19km/h.轮式集材机不能保证在不同集材路面上空载最大爬坡度都能达到15°以上,但最大爬坡速度都在20 km/h以上.在冬季坡度过大不允许集材机满载通过的路面上,为适当提高集材机爬坡度,三角履带式集材机集材质量可降至2000 kg,轮式集材机集材质量可降至1 400 kg.     

木屋圆木梁加工中心转塔式主轴结构设计与研究

通过对圆木梁加工形式的分析,确定加工中心转塔式主轴结构的总体布局方案,利用SolidWorks软件对木屋圆木梁加工中心进行三维建模。完成了矩形转塔、车外圆和铣横向榫槽主轴总成、钻孔主轴总成、铣纵向榫槽主轴总成、铣端部榫槽主轴总成、转动总成的结构设计及单位切削力、切削功率等主参数的设计计算。该设计使加工中心能够一次性进行车削、铣削、钻孔等形式的加工,大大提高了木屋圆木梁的加工精度和加工效率。     

Effects of wheeled cable skidder on rut formation in skid trail — a case study in Hyrcanian forest

The impact of skidding operations on forest soils can be divided into three major categories: soil profile disturbance, soil compaction, and soil puddling and rutting. The present study was designed as a factorial experiment in the Kheyrud Forest with a Timberjack cable skidder to evaluate the influences of number of machine passes and soil moisture of skid trails on rutting over a fine-grained soil, and to quantify these effects. The effects of soil moisture of 20% 30%, 30% 40% and 40% 50% and different levels of compaction were studied. Compaction treatments were applied using different numbers of skidding passes (1, 5, 10, 15, 20, 25, 30 times). Result shows that an increase in the number of machine passes could increase rut depth, but the majority of rutting was occurred after the initial few machine passes. Also rut depth at soil moisture of 40% 50% was higher than rut depths at soil moisture of 30% 40% and 20% 30%. The average rut depth in soil with 20% 30%, 30% 40% and 40% 50% moisture was 17, 22 and 35 cm, respectively. Rut depths were increased significantly with soil moisture and number of machine passes. It is suggested that skidding operations should be planned when soil conditions are dry in order to minimize rutting., but if skidding must be done under wet conditions, the operations should be stopped when machine traffic could create deep ruts.     

Effect of sensor quantity on measurement accuracy of log inner defects by using stress wave

Wood nondestructive testing （NDT） is one of the high efficient methods in utilizing wood. This paper explained the principle of log defect testing by using stress wave, and analyzed the effects of sensor quantity on defect testing results by using stress wave in terms of image fitting degree and error rate. The results showed that for logs with diameter ranging from 20 to 40 cm, at least 12 sensors were needed to meet the requirement which ensure a high testing accuracy of roughly 90% of fitness with 0.1 of error rate. And 10 sensors were recommended to judge the possible locations of defects and 6 sensors were sufficient to decide whether there were defects or not.     

传感器数量对应力波检测原木内部缺陷精度的影响

木材无损检测技术是高效利用木材的方法之一.该文阐述了应力波法检测木材缺陷的原理,分析了传感器数量对图像的拟合度和误差率两个指标的影响.结果表明,当原木直径在20～40cm范围内时,若需对原木缺陷进行精确测量,要求图像拟合度接近90%和误差率在0.1左右时,至少需12个传感器才能满足要求;当不需要对原木缺陷进行精确测量,只需确定缺陷的大致位置时,宜选用10个传感器进行测量;当仅仅需要判断原木是否存在缺陷时,选用6个传感器就能满足要求.图3表4参8.     

Relationship between branch-scar parameters and knot features of oriental beech (Fagus orientalis Libsky)

The classification of roundwood is inextricably linked to the measurement of a particular single wood defect. The appearance, location, and number of defects are important in the quality evaluation of logs and sawn timber, and the most important defects are knots. The purpose of this study was to investigate the relationship between the appearance of branch scars and features of the related knot inside oriental beech logs, and to model the relationship between well-defined branch-scar and knot parameters. One hundred and fifty knots in 15 stems of oriental beech trees were studied. Image analysis software was used to measure the branch-scar and knot features. The results showed a significant positive correlation between the branch-scar parameter “moustache length” and the knot length. The ratio of branch-seal length to width was found to be a good estimator of the stem diameter at the time of knot occlusion and the amount of clear wood between the knot occlusion and the bark. The relationship obtained for the oriental beech stem radius at time of knot occlusion confirms relationship reported for European beech (Fagus sylvatica L.).     

伊春林区宣贯国家原木标准情况的调查分析

过去，由于领导质量意识差，质检人员素质低，制度不健全，使得山中楞造材质量问题严重，贮木场质量问题普遍存在，管理不适应，造成资源浪费，效益流失，产品滞销。因此建议：推行ISO9000认证；按市场需求组织生产；加大标准化执法力度；建立激励机制。     

Bryophytes and decaying wood in Hepatica site-type boreo-nemoral Pinus sylvestris forests in Southern Estonia

The aim of the study was to establish the amount of decaying wood (logs and stumps) in various groups of Hepatica site-type pine forests of different age and management intensity and to analyse the composition of bryophytes in dependence of these factors. The average volume of CWD in old unmanaged forests was 47.5 m³/ha, which is rather well comparable with respective estimations from Fennoscandia. Reduced human impact contributes positively to the amount of CWD. Diversity of log diameter classes and decay stages is larger in old forests. Altogether 73 bryophyte species were recorded, 65 species on logs and 55 on stumps. Species richness on stumps was higher in managed forests than in unmanaged ones. At the same time, the species having high indicator value for man-cut stumps are very common species in boreal forests and grow on other substrata as well. Species composition and ecological conditions differed between stumps and logs. Logs are more humid microhabitats than stumps, therefore the occurrence of hepatics is more frequent on them. According to species composition on decaying wood the old unmanaged forests distinguished from others. As the differences of substratum characteristics were notable between old and young forests, the stand age described a considerable part of species variance on logs.     

Design and application of Model DZ1 log grapple driven by an electric drum

This article introduces the history and development of log grapple in China. According to the special conditions of Chinese forest areas, we have selected log grapple driven by electric drum, and have analyzed and calculated its parameters theoretically. This is the first log grapple driven by an electric drum made successfully in China. The Model DZ1 log grapple has a large closing force, works safely and is suitable for the special forest working conditions in China.     

IIS日志在网站安全中的研究与应用

针对目前网站存在的安全威胁,结合山西农业科技信息网防黑客实战经验,深入剖析了网站挂马、SQL注入攻击行为特点,通过典型实例探讨了如何利用IIS日志检测恶意攻击行为,并提出相应解决措施。同时,指出IIS日志在监控攻击行为、检测网站漏洞、预防攻击等方面的技术策略,为网站管理人员提供了一种保护网站安全的思路。