Milling of wood and wood-based materials with a computerized numerically controlled router IV: development of automatic measurement system for cutting edge profile of throw-away type straight bit

In industrial machining of timber, the method in which the operator visually inspects both wear and chippings of router bits after stopping the machine is generally adopted. However, many working hours are lost in this method and productivity suffers. Therefore, the development of a system that can automatically measure wear or chippings without stopping the machine is desirable. In this study, a laser measuring instrument was installed in a computerized numerically controlled (CNC) router, and an automatic measurement system for the cutting edge profile of throw-away-type straight bits with single-edged blades was developed. The main results are summarized as follows: (1) an automatic measurement system for the cutting edge profile of the bit was constructed; (2) this system was composed of a laser measuring instrument, a control personal computer (PC) for the CNC router, and a monitoring PC to control some devices and collect sampling data; (3) the system could measure the cutting edge profile of the bit without stopping the CNC router.Part of this article was presented at the 51st and 52nd Annual Meetings of the Japan Wood Research Society, Tokyo and Gifu, April 2001 and 2002, respectively     

Modelling spatial patterns of vegetation in desert sand dunes

A stochastic numerical approach was developed to model the actual standing biomass in the sand dunes of the northwestern Negev （Israel） and probable boundary conditions that may be responsible for the vegetation patterns investigated in detail. Our results for several variables characteristic for the prevailing climate, geomorphology, hydrology and biologicy at four measurement stations along a transect from northwest to southeast allowed for the development of a stochastic model for biomass distribution over the entire sand dune field （mesoscale） and at Nizzana experimental station （microscale）. With this equation it was possible to compute and interpolate a biomass index value for each grid point on the mesoscale and micro scale. The spatial distribution of biomass is negatively linked to distance from the sea, to rainfall and relief energy.     

Developing indicators for the sustainable management of mountain forests using a modelling approach

Methods to monitor the sustainability of forest management on local to regional scales are currently being developed in Europe, based on Pan-European criteria. However, current approaches to indicator development have several shortcomings. First, they fail to integrate the links among indicators. Second, they do not address the factors giving rise to specific indicator values explicitly. Third, they select indicators with an emphasis on data availability or ease of measurement rather than on informational content. To overcome these problems, we propose using a modelling approach to indicator development. What modelling and indicator development have in common is that they both try to capture the essence of real, complex systems. In this paper, we present an initial attempt to develop indicators for the sustainable management of mountain forests, using a modelling approach. Key issues that make the sustainable management of mountain forests a challenge, such as the poor ability of many stands to fulfil current human needs, are identified. A conceptual model depicting the most relevant system elements and links is described. In contrast to the Pan-European criteria and concept areas of sustainable forest management, which are result-oriented, the elements in the conceptual model are process-oriented. The approach could lead to a better understanding of the factors influencing the decision-making at the management unit level and to the identification of a set of meaningful indicators. To evaluate its full potential, however, a simulation model should be developed based on the conceptual model, and be applied to case studies.     

Experimental verification of bandsaw roll-tensioning theory

The validity of a bandsaw roll-tensioning theory developed by the author is verified based on a model experiment. It is shown that the actual roll-tensioning process can be clearly explained by this theory. Roll-stretching force transmission coefficients are introduced in this theory. These coefficients, which indicate the magnitude of the compression force parallel to the bandsaw surface at the roll-stretching position, are affected by the thickness of the bandsaw blade, the radius of the bandsaw blade vent at the measurement of tension, and the straightness of the bandsaw blade at the measurement of crown back, among others. For the practical use of this theory, therefore, it is necessary to determine the proper magnitude of these coefficients based on tensioning experiments.     

GPS在公路工程控制测量中的应用

GPS全球定位系统是美国研制并在1994年投入使用的卫星导航与定位系统,其应用技术已遍及国内外的各个领域。在测量领域GPS系统已广泛用于大地测量、工程测量、航空投影测量以及地形测量等方面。     

国外制浆材性状的测定技术

林木遗传改良中的遗传研究很大程度上取抉于选种目的性状的遗传变异和鉴定的技术能力.随着纸浆工业的发展对原料提出了更高的要求,物理学测量方法及化学分析技术的快速发展,与纸浆和纸品品质相关的制浆材木材性状的测定技术,近些年来在深度和广度上取得了相当成果,为大群体地开展木材性状的鉴定和比较选择提供了可能性.     

麻疯树果实发育阶段划分与性状变化动态

果实和种子性状变化与果实发育阶段存在明显的关系。本文在已有的麻疯树果实阶段划分基础上,把青果期进一步依照胚胎形态和种子形态,划分为小果实期、幼果期、皱果期和圆果期,这些阶段涵盖了果实发育的一般性阶段,而黄果期、褐果期和干果期则明显仅具有水分含量和颜色变化物理变化属性。进一步分析表明,小果实、幼果、皱果阶段为果实发育模型的I期,圆果期为Ⅱ期。麻疯树果实发育时表现为果壳先发育,种子填充后发育,长度先发育而宽度后发育的特点。定量分析表明,果实和种子性状与发育阶段之间呈现三次多项式模型,都出现了尾部下降(种子宽度例外)。此外,结籽率也明显影响了果实宽度发育和鲜重,对种子长度和宽度没有影响,但存在种子腰围变胖的现象。     

森林测树仪器使用现状与研究展望

测树仪器是森林资源调查的基本工具。结合教学、生产实习和科研体会,对近几十年来常用测树仪器的使用现状、主要特点及缺点作简要的综述与分析,并对测树仪器的发展趋势进行了展望。     

Developing a canopy closure model to predict overstorey/understorey relationships in Pinus radiata silvopastoral systems

Silvopastoral models require the development of the relationship between understorey pasture production, and the overstorey tree production. The Tikitere agroforestry trial, located near Rotorua in the Bay of Plenty, was established in Pinus radiata at a range of stockings in 1973, and monitored for stand parameters, understorey pasture production, and livestock carrying capacity between 1976 and 1992. A canopy closure model, developed for radiata pine plantations in the Bay of Plenty, shows a strong relationship (R2 ≈ 0.92) between canopy closure and the stand parameters of basal area and the ratio of green crown length to mean top height. Canopy closure was predicted for the Tikitere stands using the canopy closure model. A strong linear relationship (R2 ≈ 0.89) was shown to exist between the measured pasture production, and the predicted canopy closure. This indicates that direct assessment of canopy closure combined with a measurement of understorey pasture production, may be a simpler and more cost effective research technique than relying entirely on the continuous measurement of understorey pasture in the development of understorey/overstorey relationships. This revised version was published online in June 2006 with corrections to the Cover Date.     

中国REE复合系统耦合协调发展研究的维度、技术及影响机制

资源、环境和经济系统之间如何保持高效协同状态是我国加快推进全要素融合、地区一体化及经济高质量发展的重点研究课题.文中围绕多系统间耦合协调发展系统梳理分析了学界展开的相关研究,阐述不同系统维度下的核心研究内容,介绍多系统耦合协调关系研究的技术手段(包括测度指标体系、测算方法及结果分类和评价标准),概述多系统耦合协调发展的...     

在线测控技术在木基复合材制造中的应用现状与发展趋势

木基复合材制造中存在诸多影响人造板质量的因素，通过在线测控技术进行实时监控，可保证产品质量。介绍了智能远程在线控制系统在国内外的发展现状，提出了在线专家测控系统是今后的发展方向。     

Increased atmospheric CO2 concentration enhances the development of photosynthetic capacity beyond the temperature effect for silver birch in simulated future climate

We conducted an experiment to find out how future climate conditions will impact the spring development of photosynthetic capacity of silver birch leaves. We had two greenhouse conditions. In the simulated future climate condition, we had both elevated temperatures and CO₂ concentration, while for reference we had trees growing under current climate conditions. We used two methods to measure the development of photosynthetic capacity: first, the maximum quantum efficiency of photosystem II with a fluorescence meter; and second, the CO₂ assimilation rate with gas exchange measurements. The development of full photosynthetic capacity took around two weeks following the bud burst. The maximum quantum efficiency developed slightly faster than the CO₂ assimilation rate. Both measurement methods showed that an elevated CO₂ concentration enhanced the development of photosynthetic capacity beyond the impact of temperature only. The enhancement under the conditions of our simulated climate change translates to achieving photosynthetic capacity up to five days earlier, which impact should be taken into account in simulations of photosynthetic productivity.     

多通道土壤呼吸长期自动测量系统的集成与性能测试

全球气候变化已成为公众和科学界关注的热点。CO2作为一种重要的温室气体,其源、汇及通量的精确测定备受重视。全世界范围土壤呼吸高达     

Remote estimation of shelterbelt width from SPOT5 imagery

Width is one of the key parameters of a shelterbelt. Traditional methods to acquire this width are mainly based on field measurement, which is impractical for monitoring shelterbelts at regional scale. There are many studies analyzing linear objects, but they are not directly applicable to width detection of such objects. In this paper, we analyzed relationships among vegetation fractions retrieved from SPOT5 remote sensing imagery with 10 m × 10 m spatial resolution, shelterbelt area, and shelterbelt width in one pixel. Based on this analysis, we developed a method for recognizing shelterbelt width from a remote sensing image of central western Jilin Province, China. The result was validated by field measurement data and measurement from an aerial image of 0.5 m × 0.5 m spatial resolution. Mean absolute error was 2.40 and 2.73 m respectively, suggesting that the proposed method is feasible and its accuracy is acceptable. The study provides a valuable method for monitoring shelterbelt width across large spatial scales and an accurate input parameter for the recognition of shelterbelt porosity from remote sensing data in future research.     

Flexural and visual characteristics of fibre-managed plantation Eucalyptus globulus timber

ABSTRACT

The main goal of this study was to investigate the visual characteristics, recovery rate, and flexural properties of sawn boards from a fibre-managed plantation Eucalyptus globulus resource as a potential raw material for structural building applications. The impacts of the visual characteristics, strength-reducing features, and variation in basic density and moisture content on the bending modulus of elasticity (MOE) and modulus of rupture (MOR) of the boards were investigated. The reliabilities of different non-destructive methods in predicting MOE and MOR of the boards were evaluated, including log acoustic wave velocity measurement and numerical modellings. The MOE and MOR of the boards were significantly affected by the slope of grain, percentage of clear wood, and total number of knots in the loading zone of the boards. The normal variation in basic density significantly influenced the MOE of the boards while its effect on the MOR was insignificant. The numerical models developed using the artificial neural network (ANN) showed better accuracies in predicting the MOE and MOR of the boards than traditional multi-regression modelling and log acoustic wave velocity measurement. The ANN models developed in this study showed more than 78.5% and 79.9% success in predicting the adjusted MOE and MOR of the boards, respectively.     

TMJ-A人造板弹性模量无损检测显示机的误差因素分析

人造板无损检测是在线检测结构用人造板力学性能、保证产品质量的重要环节。本文介绍了弹性模量无损检测设备的功能和工作原理 ,从测试方法、机械系统、控制系统几个方面入手 ,分析了测试误差的形成原因及影响因素 ,为进一步提高人造板无损检测设备的测试精度和可靠性提供依据     

三维激光扫描与雕刻机集成系统的研究

激光扫描测量和雕刻机的集成是一项新技术，基于自主研发的激光扫描软件解决了与雕刻机系统集成过程中所遇到的扫描点云数据转换、激光测头的安装与固定、运动控制系统的一致性等问题。相比传统的手工雕刻和手工电脑绘图，其成倍地提高了加工效率。     

New monitoring concept of moisture content distribution in wood during RF/vacuum drying

A new method for monitoring moisture content during radio-frequency (RF)/vacuum drying was developed by measurement of temperature and pressure in wood. Temperature and pressure inside the wood were measured simultaneously during RF/vacuum drying at the same point. The relative humidity (RH) and moisture content (MC) below the fiber saturation point (FSP) were calculated based on temperature and pressure, and the relationship between the temperature, RH, and equilibrium moisture content (EMC) at the measurement point. When the moisture content was below the FSP, the calculated MC was slightly greater than the value given by oven drying. The absolute error was within 0.8% near the open cross side, and was within 1.8% at another measurement point. Thus, we concluded that it was practicable to monitor the moisture content below the FSP according to the temperature and pressure inside the wood. Part of this study was presented at the 15th Annual Meeting of the Chugoku Shikoku Branch of the Japan Wood Research Society, Higashi-Hiroshima, Japan, September 2003     

林地面积的勘测技术及误差分析

林地资源不仅是林业发展的基础,而且是控制森林资源消耗,增强森林生态防护效益,实现国民经济可持续发展的根本与保障。林地面积勘测技术在林地资源的有效利用和保护中具有重要的意义。本文对多种控制测量技术进行分析,比较各种方法的精度和效率,在满足测量精度要求下,选择更好的方法与技术进行林地面积勘测,能更快更好地完成测量任务。     

旋刀式草坪修剪机噪声评价分析

介绍了草坪修剪机的发展概况,对国内外5种旋刀式草坪修剪机操作者耳旁噪声进行测定,分析引起噪声的主要原因,提出了降低修剪机耳旁噪声影响的建议.