木材抓具抓爪的可靠性分析

本文在分析木材抓具工作受力的基础，运用可靠度干涉理论，对抓爪的工作可靠度进行了计算，提出了提高抓爪工作可靠度的方法。     

机械加工实现可靠度全面质量管理的探讨

从机械加工工序过程实现可靠度控制加工质量的现点出发，引用可靠度理论，运用控制图，并用实例探讨了可靠度理论在机械加工中实现全面质量管理的方法。     

钢板弹簧疲劳寿命可靠性计算

在讨论钢板弹簧疲劳寿命概率分布的基础上，研究了可靠度和置信度问题，给出了利用三参数Weibull分布计算疲劳寿命和可靠度的公式，计算实例表明，该法可方便地对所要求的任意可靠度和置信度进行寿命计算。     

机床可靠性与维修性指标的统计分析

ＣＡ６１４０普通车床是国产最典型、使用量最大的金属切削机床。该型号机床的切削性能好、价格低。但据用户反映其使用可靠性和维修性尚不理想。为此，我们在吉林市几家机械加工企业随机抽取了８台正在使用中的机床做样机，查阅了近几年来使用与维修方面的有关数据。就其可靠性与维修性做了统计分析。１可靠性分析 机床可靠性是指机床在规定条件下和规定时间内完成规定功能的能力，常用可靠度Ｒ（ｔ）做定量描述。１．１可靠度与平均故障间隔时间 可靠度表示设备在规定条件下和规定时间内完成规定功能的概率，其表达式为：式中：ｔ－时间，…     

林区公路桥梁结构系统可靠度分析的理论方法

本文是林区公路桥梁结构系统可靠度分析课题的总则。在本文中,作者从系统工程的观点出发,运用结构可靠度理论,构造了林区公路桥梁系统可靠性分析的理论框架,并首次将桥涵水文对系统可靠度的影响纳入工程大系统之中,并讨论了各子系统可靠度对整个系统可靠性影响的权重问题,初步探了基于系统可靠度的大系统优化问题。     

基于逆向FTF法的RFER值地铁车门风险主动管理研究

车门系统作为地铁车辆中的关键子系统，其系统运行可靠性密切关系到乘客的人身安全和运营的服务可靠度。据国内某地铁公司五年线网运营数据统计，因车门系统导致晚点占比线网总晚点数为54%,人为导致车门无法关闭的晚点占比27%,部件故障导致晚点的占比27%。可以看出，车门系统的设备可靠度在线网服务可靠度中起了决定性作用。针对上述问题，采用基于逆向FTF(FTA-FMEA)的可靠性分析方法，以设备寿命评估为基础，融入危险度(Risk)、频度(Frequency)、经济度(Economy)、修复度(Repair)构建动态RFER系数值作为主动管理导向，通过寿命评估、可靠度计算、RFER动态风险系数值评估，以制定合理的维护策略，有效提升车门设备运营可靠性。     

木本香料植物─少花桂

介绍了木本香料植物—少花桂在贵州省的分布、生境和群落，并进行了引种繁殖，苗期结果为：1年生营养袋苗平均高17．0cm，最高19．0cm，平均地径0．364cm，平均根深18．3cm；裸根苗平均高24．6cm，最高30．2cm，地径0．395cm．平均根深12．6cm；苗期应进行适当遮荫。     

不同轻型基质对马尾松容器苗生长的影响

试验表明，不同轻型基质配方对马尾松容器苗有重要影响，生长差异明显，方差分析和多重比较表明，大部分达到了极显著和显著差异。在几个方面同时表现较好的配方是：3号（泥炭土0．2＋锯屑0.8）、6号（炭土0．6＋锯屑0．2＋稻谷壳0．2）和13号（泥炭土0．46＋锯屑0．27＋稻谷壳0．27），可在生产中推广应用。     

朝仓花椒组织培养快繁试验

以朝仓花椒为试材，研究了其组培快繁技术。试验表明，4～5月份接种外植体易获得无菌苗；初期适宜的增殖培养基为MS＋6-BA1．0mg／L（单位下同）＋IBA0．2＋3．0％蔗糖，继代增殖培养基为MS＋6-BA0．5＋IBA0．1＋3．0％蔗糖，适宜的生根培养基为1／4MS＋NAA0．3＋2．5％蔗糖，移栽最佳基质为蛭石。     

板栗主要栽培品种的遗传学分析

应用RAPD分子标记手段，研究了品种间的遗传多样性。对46个板栗品种样品的DNA，用1个引物进行扩增反应，产生69个多态位点。结果表明，各个位点上遗传多样性程度存在较大差别，有效等位基因数目（Ne）最大值为1．9990，最小值为1．0444；基因多样度（H）的最大值为0．4998，最小值为0．042；Shannon信息指数的最大值为0．6929，最小值为0．1047。所检测位点的平均有效等位基因数目为1．5260，平均基因多样度为0．3618，平均信息指数为0．4832。有效等位基因数目、平均基因多样度和平均Shannon信息指数的标准误都较小，分别为0．3096，0．1418，0．1748，估计精度较高。这3个遗传多样性度量表明板栗品种间具有较高的遗传多样度。品种间遗传距离最大值为0．8001，相应的遗传共享度为0．4493；品种间遗传距离最小值为0．0910，对应的遗传共享度为0．9130。遗传距离是评价品种间近缘关系的重要指标。对板栗品种间的遗传分析，是板栗良种选育和品种间亲缘关系的理论基础。     

深栽造林钻孔机钻头结构的有限元分析及优化

钻头是深栽造林钻孔机最重要的工作部件,强度和变形是钻头设计过程中必须考虑的问题。利用SolidWorks Simulation插件对深栽造林钻孔机钻头进行了有限元分析,并在此基础上对钻头结构进行了优化,使钻头厚度减小了2mm、质量减轻了2．1kg,达到了结构优化的目的。     

关于钻孔桩终孔的探讨

桥梁桩基础施工中,设计图的工程地质勘察资料普遍存在与实际不符的情况,为了防止钻桩终孔的盲目性,同时为了防止过分的保守,本文结合实际对钻孔桩终孔问题进行探讨。     

冲击钻冲孔埋钻事故的处理

该文详细的介绍了简便可行的钻孔灌注桩施工中埋钻事故的处理方案。 即先用钻井法提取被埋钻颈,原地回填后再重新造孔、这样可以不修改设计方案节省费用,在一般中小型施工中可以实施。     

Induction of discolored wood in Scots pine (Pinus sylvestris)

Induction of discolored wood in Scots pine (Pinus sylvestris L.) trees by treatment with ethylene, carbon dioxide, nitrogen (hypoxia) or wounding from early April to late September was investigated. All treatments induced formation of discolored wood upward and downward from the drill hole. The amount of discolored wood formed above the drill hole depended on the treatment in the following order: ethylene > carbon dioxide = nitrogen > wounding; and below the drill hole in the order: ethylene > carbon dioxide = nitrogen = wounding. Based on chemical analyses (HPLC/UV, GS/MS, LC/MS and 1H-NMR), discolored wood induced by wounding or treatment with ethylene or carbon dioxide showed compositional similarities to natural heartwood, whereas discolored wood induced by nitrogen treatment showed fewer similarities to natural heartwood. The results suggest that ethylene is an important factor controlling heartwood formation, although wounding and internal concentrations of carbon dioxide may also play a role.     

核桃楸不同整地方式育苗效果

根据凤城边门苗圃的山区气候和土壤特点,采用垄作、床作、畦作3种整地方式进行播种育苗试验,结果表明,辽东地区核桃楸育苗选择垄作整地方式比床作和畦作整地效果好,能显著提高苗木生长量和生根量。垄作比床作和畦作整地育苗地径提高71.74%和122.54%,其他各项指标提高的幅度也都达到了55%以上。     

Using drill resistance to quantify the density in coarse woody debris of Norway spruce

To evaluate the mass of coarse woody debris (CWD), it is necessary to quantify its density. Drill resistance measurements are introduced as a approach to estimate the density of CWD in different stages of decay. Dead logs of Norway spruce [Picea abies (L.) Karst.] from a Central European mountainous site were used as a test system to compare the new method with conventional predictors of wood density such as fast quantitative field estimates (e.g., knife probe) and classification of decay classes based on a set of qualitative traits and quantitative estimates. The model containing only drill resistance as a predictor explained 65% of the variation in wood density and was markedly better than models containing one or more of several conventional predictors. However, we show that the relationship between drill resistance and gravimetric wood density relationship is sensitive to the decay status. Therefore, the best model combines drill resistance and decay class (adj. R2 = 0.732). An additional experiment showed that drill resistance is also sensitive to the moisture state (fresh vs. oven-dry) of the sample. The major potential of the method lies in its non-destructive nature which allows repeated sampling in long-term ecosystem studies or in protected areas where destructive sampling is prohibited. The limitations of the method are discussed and recommendations for applications are given.     

Combined effect of wood moisture content,drill bit rotational speed and feed rate on drilling resistance measurements in Norway spruce (Picea abies (L.) Karst.)

ABSTRACT

An IML-RESI PD 400 drilling tool and a standard spade drill bit (IML System GmbH, Wiesloch, Germany) were used to study the combined effect of wood moisture content (MC), drill bit rotational speed and feed rate on drilling resistance (DR) and feeding force (FF). Tests were made with Norway spruce (Picea abies (L.) Karst.) conditioned in a normal climate (20°C/65% RH), at 20°C/95% RH, vacuum-pressure impregnated in water, and oven-dried. Rotational speeds and feed rates had an impact on feed rate per cutting edge for the major cutting edge of the drill bit which was used for correlation with DR and FF for various MC. Impact of MC on DR and FF depended on rotational speeds and feed rates of the drill bit. For feed rates per cutting edge less than 0.09?mm, DR was higher for water saturated (WS) specimens. Negligible differences between DR for various MC were found for feed rates per cutting edge between 0.09 and 0.15?mm. DR was higher at low MC for feed rates per cutting edge which were higher than 0.15?mm. FF extremely increased in conditioned (20°C/95% RH) and WS specimens at feed rates per cutting edge less than 0.1?mm.     

钻掘推进--地下管线工程施工新技术简介

本文介绍了钻掘推进技术的原理和施工方法。     

钻孔灌注桩坍孔的预防与处理

本文分析了在粉砂土地质情况下，桥梁钻孔灌注桩施工中发生坍孔的原因，提出了坍孔的预防及处理方法。     

Comparison of ground disturbance of frozen peatland during stump harvesting using a stump drill and rake

ABSTRACT

Tree stumps could be a source of renewable energy, contributing to a reduced dependence on fossil fuels. In Finland, stumps are currently harvested when the ground is not frozen to avoid co-removal of large amounts of soil and stones. Hence, the machinery used for stump extraction is not operated year-round. On peatlands, stumps could potentially be harvested when the ground is frozen. However, peatlands are highly sensitive to ground disturbance. There is, therefore, a need to identify equipment that causes low ground disturbance. In this study, peatland ground disturbance at stump level caused by stump harvesting using either a stump drill or a conventional stump rake was evaluated and compared in winter conditions. Results show that the stump drill caused up to 90% less ground disturbance per harvested stump than the conventional stump rake, but harvested 32–53% of the stump wood. Additionally, the size and shape of the disturbed areas changed between the harvesting year and following year, indicating that frost heaving plays a role in filling holes caused by stump extraction. The stump drill also consumed similar time to the conventional stump rake when harvesting Scots pine stumps on mineral soils, but far more when harvesting Norway spruce stumps.