森林火灾无线报警器的设计

采用温度传感器、红外热释电传感器以及烟雾传感器,对森林火灾产生的高温、红外线和烟雾进行检测,检测信号通过相应的放大和专用芯片处理之后,送入专用多路传感器信号综合处理芯片KBS5200进行数据的模拟—数字转换,并通过内部逻辑电路进行与或逻辑运算,最后通过GSM智能控制器利用现有的手机网络进行远程报警。其主要优点是:最大限度地避免了误报警和漏报警,而且利用高效率太阳能电池板和高效能锂离子电池解决了供电的难题。     

古建筑修缮用原木的贮存保管技术

古建筑木构件的修补和更新成为古建筑修缮中主要任务之一.其间,所用原木在贮存期的保管是亟待解决的课题.通过故宫百年大修中对所备原木保管的实践,提出在备料的同时,需对原木采取防腐防虫处理和进行规范的保护工艺.鉴于我国南北方气候条件复杂,危害生物的种类区别较大,采用保护防治处理的工艺也应因地制宜、有所不同.     

Use of wood products in multi-storey residential buildings: views of Swedish actors and suggested measures for an increased use

ABSTRACT

Many studies have shown that wooden buildings in general have a lower climate impact than buildings built of conventional materials such as concrete and steel. In Sweden, however, only about 10% of the multi-dwelling buildings are built with timber frames. The goal of this empirical study is to provide a broad picture of the views of Swedish actors regarding the use of wood products in multi-storey residential buildings and suggest measures for an increased use. A questionnaire concerning the use of wood products in construction was sent out to Swedish developers, main contractors, and architects and 100 answers were received. The study shows that the views of the groups of actors differ in some respects and factors that may either facilitate or be obstacles to an increased use of wood products were identified and discussed.     

Basic study on nondestructive evaluation of artificial deterioration of a wooden rafter by ultrasonic measurement

Most old buildings in Korea are wood framed and, with age, deterioration is found in all wood components of antique buildings. Insects and rapid changes in humidity are among the main causes of deterioration. To preserve antique wooden buildings, nondestructive testing (NDT) methods are required. Various methods of nondestructive evaluation (NDE) such as X-ray, stress wave, drilling resistance test, and ultrasound are used to inspect the safety of wooden antique buildings. The ultrasonic method is relatively simple, inexpensive, and accurate. The rafters are one of the main components of antique buildings and are seriously affected by deterioration. This study aimed to develop a nondestructive ultrasonic technique for evaluation of wooden rafter deterioration. Regression models describing the relationship between the artificial deterioration of the specimen and ultrasonic parameters were proposed. The method was found to be reliable for evaluating wooden rafter deterioration.     

木材干燥应力连续监测方法的研究

本文在卡普法的基础上，提出了木材干燥应力连续监测方法，并设计了所需的配套装置。该方法采用涡流传感器对干燥过程中卡普片的矢高进行连续测试，同时通过计算机自动采集、存储数据。结果表明：矢高与干燥时间存在精密的相关性，它们之间的相关系数大部分达到0．99以上，从而实现了木材干燥应力的自动与连续监测。     

古建筑木结构的无损检测新技术

将三维应力波断层扫描仪和阻力仪应用于古建筑木结构的勘查中.试验室预试验及现场勘查实例证明,三维应力波断层扫描仪完全适用于木构件的勘查,与阻力仪结合使用,可使勘查操作更便捷,结果更准确.     

无线传感器网络及其在林业中的应用

综述了无线传感器网络(Wireless Sensor Networks,WSN)的节点构成、体系结构、研究热点以及在森林火灾监测和救灾、自然保护区生态多样性监测、生态环境监测、木材检测、精准林业中的应用研究现状,表明其在林业中的应用虽然尚处于起步阶段,但其扩展了传统资源管理的能力,尤其数据采集上更突破传统方法的局限,有着广阔的应用前景。     

Development of a monitoring system for guided circular saws: an experimental investigation

ABSTRACT

Lack of a monitoring system for guided circular saws marks one of the most critical machines in sawmills as a production bottleneck. Monitoring systems are being researched and developed for machine tools, especially for the metal cutting industry; but there are limited studies on the development of monitoring systems for circular saws in wood manufacturing process. In this study, sensors with the possibility to indicate sawing deviation were chosen that could be mounted in or on the saw guides. The sensors were: a microphone, an accelerometer, temperature sensor, an acoustic emission (AE) sensor, and a newly developed displacement sensor. A load cell was used to measure the lateral force on the guides. The outputs from these sensors were compared to the standard deviation of the board surface measured at the top of the cut. The signals from the displacement sensor, microphone, accelerometer, guide force sensor, and AE senor had no correlation to changes in the sawing deviation as measured by the standard deviation at the top of the board. Under laboratory conditions, the sound level and the AE signal did indicate the beginning and end of the cut. It was found that blade temperature is a good indicator of saw cutting performance. A newly developed temperature sensor can provide accurate temperature of the saw during cutting. The sensor can be used for measuring the rate of heating to cooling over time which can be used as a monitoring system to detect if there is any issue in the system.     

Density calculation of wood by portable X-ray tube with consideration of penetrating depth

A portable X-ray apparatus generates soft X-rays which have a continuous wavelength (wide range). When using continuous wavelength X-rays, the mass attenuation coefficient of the soft X-rays is changed as the penetrating depth in wood increases, unlike monochromatic X-rays which are usually used for medical purposes. In safety inspections of historic buildings, penetrating depth varies in an X-ray radiograph. Computerized tomography (CT) is a powerful tool that helps determine the density information of the inner sections of buildings. Because only portable X-rays can be used in historic buildings and the penetrating depth can vary, the mass attenuation coefficient of wood according to penetrating depth needs to be investigated. Therefore, in this study, we developed a statistical method which takes into account the influence of the penetrating depth on a density calculation made by a portable X-ray apparatus. X-ray tests were conducted on wood specimens of various depths. From the results, a statically determined mass attenuation coefficient (SMAC) ( $ \mu = - 0.214\ln (t) + 0.7251 $ ), which is the equation of mass attenuation coefficient according to the penetrating depth in wood, was derived to convert radiographs to density radiographs. All projections were converted into density profiles using two methods, average mass attenuation coefficient and SMAC. Based on the density profile for each projection, a density distribution of a cross-section was reconstructed by filtered back projection. Compared with the cases using a consistent mass attenuation coefficient, SMAC provided much higher precision in density prediction than the average mass attenuation coefficient.     

Plate-type waveguides for detecting acoustic emissions generated by termite attacks

To examine the feasibility of using plate-type waveguides for effective detection of acoustic emissions (AEs) from termite attacks in wood, AEs generated by breaking pencil leads or by termite attacks were detected using an AE sensor with a resonant frequency of 140kHz with steel plates of four different sizes and thickness and three AE sensors without them. The larger plates were associated with larger amplitudes of the artificial AEs. The amplitudes of AEs detected by an AE sensor with a steel plate larger than 30×30mm were greater than the average amplitude of the artificial AEs detected by three AE sensors. When detecting AEs generated by the feeding activity of workers,Coptotermes formosanus Shiraki, the cumulative AE events detected by the sensor with a steel plate were much larger than those of the three AE sensors without a plate. Because AE waves are attenuated much less in a steel plate than in wood, it is more effective to attach the AE sensor to wood with a steel plate rather than directly to the wood. These findings suggest that it is feasible to use an AE sensor with a plate-type waveguide for the nondestructive detection of termite attacks in wood.     

Modelling the distribution of wood properties along the stems of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) as affected by silvicultural management

In this work, empirical ring-based models were developed to predict the distribution of early wood percentage, wood density and fibre length along the stems of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) as affected by silvicultural management. The performance of the ring-based models was also compared for Scots pine and Norway spruce with corresponding disc-based (cross-sectional) models. Moreover, both models were integrated with example simulations by a process-based growth and yield model to analyze how management, such as thinning, affects the growth and wood properties of Scots pine trees over a rotation as an average for the tree stem, but also along the stem.The ring-based models built for annual early wood percentage (explained by ring width), air dry wood density (explained by early wood percentage and cambial age) and fibre length (explained by radial growth percentage and cambial age) predicted reasonably well the wood properties both at an intra-ring level, but also at a cross-sectional level. These predictions were also reasonably well in line with corresponding cross-sectional predictions by the disc-based models (which predicted the properties based on the number of annual rings and diameter at breast height and/or the cross-section being considered and temperature sum). The example simulations also demonstrated that both models predicted slightly lower wood density for dominant trees compared to dominated ones grown in thinned and unthinned Scots pine stands over a rotation. Unlike the disc-based model, the ring-based model predicted, on average, higher early wood percentage in dominant trees than in dominated ones. However, fibre length was not significantly affected when the averages of the whole stems were predicted, and this held true for both ring- and disc-based models.In summary, the incorporation of empirical ring-based wood property models into a process-based growth and yield model, offers a means to study in detail how environmental conditions, forest structure and management affect the quantity and properties of stem wood produced over a rotation. The disc-based wood property models used in this work are based on data with large geographical and genetic variation, and therefore may turn out to be more applicable for predicting future wood and fibre resources at a regional and national level. This kind of integrated use of wood property models with a process-based growth and yield model could help us to evaluate the forest resources under current and changing climate.     

Social housing and green space: a case study in Inner London

Urban woodlands and green spaces provide a range of benefitsto people in densely populated areas: as places to use, viewand enjoy. There is increasing interest in green spaces andtheir impacts on people's quality of life. The work describedin this paper involved a partnership between Peabody Trust,a social housing association; the Forestry Commission and Treesfor Cities, an environmental charity. The aim of the projectwas to involve residents in the use and enjoyment of their localwoodland. The research gained an understanding of how the residentsof two housing estates in South London view and experience theirlocal woodland, called Peabody Hill Wood. Three focus groupsand a questionnaire were undertaken with residents. Observationswere also made at a community activity day and walk throughthe wood with local residents. From the analysis of the data,there was a complex mix of attitudes towards Peabody Hill Woodthat related to not only the management of the wood but alsothe management of the buildings by Peabody Trust. This researchhighlights, as a number of other studies have, that woodlandsnear to where people live are valuable spaces and play a significantrole by providing opportunity for contact with nature. Key implicationsof the research suggest that housing associations can have animportant role to play in green space management. Partnershipworking with the environmental sector can help bring about muchneeded improvements to the environment. Working with communitiesand sustaining long-term commitment are also advocated.     

木材渗透性的控制因素及改善措施

鉴于木材渗透性对高效加工与利用木材的重要作用,从木材渗透性的主要影响因子及改善措施等方面进行综合分析,并指出其主要发展方向.木材渗透性的控制因素方面,应进一步借助SEM-EDX,TEM,FTIR,NRM,CT等先进手段,深入分析木材的主要渗透通道,以更精准地确定主要影响因素;木材浸注技术方面,应注重联合多种技术,或开发应用集多重功能于一体的综合新技术,以更好地改善木材渗透性.     

无线传感器网络在森林监测中的应用

在对森林监测无线传感器网络的网络体系结构、管理平台结构、研究热点,以及在森林监测中的应用研究现状进行阐述的同时,针对森林环境监测、森林防火等领域提出了无线传感器网络应用的方案与思路。     

国内外木结构建筑耐火性能的研究进展

为推动现代木结构建筑在国内的发展,分析了木结构建筑耐火的关键性,重点介绍了近二十年来国内外在木结构建筑耐火模拟测试、建筑及其结构耐火极限试验、防火材料应用和软木制品的保温隔热检测与耐火应用等方面的研究进展及成果。在学习和借鉴的基础上,通过总结国外研究成果和经验,提出目前国内在木结构建筑耐火研究方面尚存在的一些问题,与国外相比研究工作的薄弱环节。建议在国内外已有的木结构建筑相关标准规范基础上,加强国内在木结构建筑防火研究的理论基础工作,尤其是模拟试验研究,为木结构建筑的耐火性能评估奠定基础。同时,强调软木材料自身特性,提出在木结构建筑构件及其连接节点处使用软木材料覆面,在保证实用性的基础上,还起到绝缘、隔热、装饰的作用,进一步提高木构件的防火性能,从而提高建筑整体的耐火性。通过上述分析,以期为我国现代木结构建筑防火优化设计提供有益参考。     

Research Advance of Near-infrared Spectroscopy in Wood Anatomical Characteristics Estimation

As a newly current advanced analysis technology,the near-infrared(NIR)spectroscopy possesses advantages of easy operation,fast and accurate detection,low cost and non-destructive test, has been widely used in the fields including pulp manufacturing and paper-making,wood properties estimation,wood progressing,wood composites producing and wood protection.In present work, based on introduction of the basic principles of NIR and its main characteristics,an overview was conducted focusing on the research status of wood anatomical characteristics(including cellulose crystallinity,microfibril angle and fiber morphology) estimation by using NIR spectroscopy.Moreover, the application trends were prospected.     

Quantitative estimation of carbon removal effects due to wood utilization up to 2050 in Japan: effects from carbon storage and substitution of fossil fuels by harvested wood products

Carbon absorbed by forests remains stored in the timber used for wood products, and a change in wood product stock can be evaluated as substantial removal/emission of atmospheric carbon. Since the carbon storage effect due to harvested wood products (HWP) might be taken into account in the future framework of carbon mitigation, it is crucial to estimate the carbon fl ow and stock concerning HWP for the next commitment period. In the present study, we developed a model for estimating the fl ow and stock of wood products in Japan’s building, furniture, and paper sectors. The HWP carbon storage effect and substitution effect (carbon reduction by substituting fossil fuels and energy-intensive materials with HWP) up to 2050 were quantitatively estimated by lifetime analysis. Our model simulation revealed that (i) the carbon stock change in Japan due to HWP would be evaluated as a large emission if the atmospheric-fl ow approach is adopted, (ii) carbon removal would not significantly increase if the ratio of newly constructed wooden buildings/furniture remains stable, and (iii) the carbon storage effect together with the substitution effect would have a significant impact on climate change mitigation if the ratio of newly constructed wooden buildings/furniture is gradually improved to 70% by 2050.     

时域核磁共振技术在木材科学研究领域的应用

时域核磁共振技术（TD-NMR）作为一种先进的表征手段,能快速、精准测量木材中自由水和吸着水的动态变化,也可以基于水分信息表征木材孔隙分布,因此已被广泛应用于木材科学研究领域。文中归纳了时域核磁共振技术用于测量木材含水率、水分性质、水分分布及木材孔隙分布的方法,并对主要研究结果进行综述,以期为相关领域的研究和应用提供理论参考。     

大数据视域下木材流通企业的供应链管理策略研究

随着我国社会主义市场经济体系的不断完善,现代化企业的管理模式和产业结构逐步科学化、精细化。而木材流通企业作为木材贸易的重要载体,应用先进的技术和经营模式强化供应链管理,有助于促进木材资源创造丰富的社会价值和经济效益。介绍了大数据环境下企业供应链管理特点,分析了木材流通企业供应链管理大数据优势,对大数据视域下木材流通企业的供应链管理进行展望。     

To thin or not to thin: bio-economic analysis of two alternative practices to increase amount of coarse woody debris in managed forests

Maintenance of biodiversity in commercial forests has become a main goal in forestry, and several new management principles to reach that goal have been introduced lately. For example, in even-aged forestry, tree retention (leaving a proportion of trees standing in clear-cut sites) is widely used to increase the structural diversity and the amount of dead wood in forests. However, the cost-efficiency of the new management principles is poorly studied. To increase the amount of dead wood, an alternative way could be a change in the thinning regime, so that the self-thinning builds up of woody debris of a growing stand. We used long-term (200?years) simulations to compare ecological and economical effects of the two alternative management practices to increase the amount of dead wood in forest stands: (1) green tree retention and (2) growing stands unthinned. We simulated stand growth and management of 12 pine and 12 spruce stands that represented sites in different parts of Finland. We found that growing stands unthinned produced about 5–6?times more dead wood than retention with 20 trees left per hectare. In terms of economical loss, leaving stands unthinned reduced the net present value of harvest revenues less than 20%. Consequently, leaving stands unthinned offers a cost-effective option to increase the amount of dead wood in commercial forests. The effects of unthinned management were, however, dependent on thermal sum and initial stand density, indicating that biodiversity-oriented management practices should be designed for local conditions.