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1.
Dynamic properties of bamboo, Phyllostachys pubescens, with moisture content (MC) ranging from −130 to 130°C, were studied by dynamic mechanical analysis (DMA). The results showed
that the hygrothermal effect on dynamic mechanical properties was negative. The storage modulus decreases with increasing
temperature and MC, and glass transition temperature decreases with increasing MC. The glass transition temperature and tan
delta of bamboo were 30.5°C, 0.02 and 10.61°C, 0.04, when MC was 10% and 34%, respectively.
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Translated from Journal of Nanjing Forestry University (Natural Sciences Edition), 2006, 30(1): 65–68 [译自: 南京林业大学学报(自然科学版), 2006, 30(1): 65–68] 相似文献
2.
In order to analyze the effect of temperature gradient on moisture movement during highly intensive drying, such as microwave-vacuum
drying, the profile of the temperature and moisture content in sealed wood whose opposite faces were subjected to temperature
gradient for a short time was measured. The ratio of the moisture content (MC) gradient to the temperature gradient (dM/dT) was calculated and the factors influencing moisture movement under nonisothermal conditions were discussed. The results
indicate that moisture moved in wood from the warm surface to the cold one even if opposite faces of the sealed wood assembly
were exposed continuously to different but constant temperatures for a short period. The moisture content on the cold surface
was higher than that on the warm surface. The moisture content gradient opposite to the temperature gradient was established,
and the dM/dT was below 0.9%/°C. The temperature in the sample and the distance from the hot surface of the sample was strongly linearly
correlated. With an increase in temperature, initial moisture content and experimental time, the dM/dT was significantly increased.
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Translated from Journal of Beijing Forestry University, 2005, 27(2): 96–100 [译自: 北京林业大学学报, 2005, 27(2): 96–100] 相似文献
3.
The technology of liquefying processed-waste bamboo with phenol is investigated by single factor trials and an orthogonal
design. We studied the preparation technology and properties of adhesives from this phenol-liquefied bamboo with formaldehyde
(BPF). The results show that temperature has a significant effect on liquefaction. The effect of the mass ratio of phenol
to bamboo comes second and the catalyst dosage within the range of 2%–4% is the least effective. The optimum conditions of
liquefaction are as follows: a mass ratio of phenol to bamboo 3.5, a catalyst dosage of 4%, liquefying temperature 145°C and
liquefying time 60 min. The liquefaction rate of bamboo reached 99.1%. For the preparation of the adhesive, a mass ratio of
liquefied bamboo products to formaldehyde (37%) is 100 to 164.8–199.5, while the ratio 100 to 108.2 is the best. This adhesive
has a lower curing temperature than that of normal PF resin. At a hot-press temperature of 130 or 140°C, this new adhesive
provides excellent bonding strength of plywood. The most favorable temperature for hot-pressing is 140°C.
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Translated from Chemistry and Industry of Forest Products, 2007, 27(6): 65–70 [译自: 林产化学与工业] 相似文献
4.
Qiang Liu Shaolin Peng Hua Bi Hongyi Zhang Zhi’an Li Wenhui Ma Niya Li 《Frontiers of Forestry in China》2006,1(3):243-252
In order to explore the release of nutrients and the effects of global warming on the decomposition rate of forest litter,
an experiment is designed to reciprocally decompose forest foliar litter in two sites across climatic zones: Mt. Jianfengling
in Hainan Province in the tropics and Mt. Dinghushan in Guangdong Province in the subtropics. The two sites have similar altitudes,
soil types, annual mean rainfall and seasonality of dry and wet. The main difference between these two sites is the annual
mean temperature with the difference of 3.7°C. Foliar litters of 10 native dominant tree species have been collected respectively
from the two sites and divided into single-species litter and mixed litter. They are decomposed reciprocally in the two sites.
The results indicate that litter decomposes in the tropical site 1.36–3.06 times more rapidly than in the subtropical site.
Apparent Q
10, calculated on the basis of the temperature difference between the two sites, ranges from 3.7 to 7.5. The return amount of
N, P and C will increase by 32.42, 1.033 and 741.1 kg/hm2, respectively in Mt. Dinghushan in the first year’s litter decomposition under the prevailing temperature condition. Only
in Mt. Dinghushan is the correlation between decomposition rate constant and initial litter quality high and significant in
the ratio of lignin to N, lignin, the ratio of lignin to P, HLQ and C. This is not the case at Mt. Jianfengling.
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Translated from Journal of Beijing Forestry University, 2005, 27(1): 24–32 [译自: 北京林业大学学报, 2005, 27(1): 24–32] 相似文献
5.
Lili Zhang Zhenyu Li Hailin Li Ruidong Han Yongli Zhao 《Frontiers of Forestry in China》2006,1(4):453-459
Chinese pine caterpillar (Dendrolimus tabulaeformis) larvae were fed with pine needles of different degrees of damage to evaluate the effects of pine needles on the growth and
development of larvae. The results showed that the nutritional index of the larvae declines after feeding on the damaged pine
needlings. The lowest amount of food ingested and voided feces, the lowest nutritional index, slowest development, lightest
pupae and most mortality were found in those pine caterpillar larvae fed with pine needles which were 50% damaged. The damaged
pine needles significantly affected the population dynamics of Chinese pine caterpillars. The nutritional indices of larvae
fed with 25% and 75% damaged pine needles were similar. The nutritional index of the dark morphs was higher than that of the
tinted morphs, however, their mortality was lower than that of the tinted morphs. This phenomenon was reversed at the later
stage of development when the larvae were fed on 50% damaged pine needles.
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Translated from Journal of Beijing Forestry University, 2005, 27(6): 83–88 [译自: 北京林业大学学报, 2005, 27(6): 83–88] 相似文献
6.
Haijun Liu Youqing Luo Junbao Wen Zhiming Zhang Jihua Feng Wanqiang Tao 《Frontiers of Forestry in China》2006,1(3):328-335
According to the international methods of pest risk analysis and urban forestry characteristics in Beijing, a quantitative
risk assessment system in Beijing for three primary non-indigenous pests was proposed. This system was used to analyze three
major non-indigenous species, Dendroctonus valens, Hyphantria cunea, and Apriona swainsoni. The results show that the risks of these three pests in the Beijing area were 2.46, 2.30, and 2.02, which were all highly
risky. Based on the result and extensive risk communications, combined with the management experience of the Beijing Forest
Protection Station, the authors proposed some effective control measures to prevent the invasion of the three pests into Beijing.
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Translated from Journal of Beijing Forestry University, 2005, 27(2): 81–87 [译自: 北京林业大学学报, 2005, 27(2): 81–87] 相似文献
7.
The regeneration of exhausted solutions of electroless nickel plating wood veneer was realized using soluble calcium salt
to precipitate and remove phosphite and then using fluoride to remove residual calcium ions from the solution. The effect
of the pH value of the solution, treatment temperature and the molar ratio of calcium ions to phosphite ions on the removal
efficiency of phosphite was investigated. Wood veneer was electroless plated using regenerated solutions. A coating with better
electrical conductivity and electromagnetic shielding was obtained.
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Translated from Journal of Northeast Forestry University, 2005, 33(3): 47–48 [译自: 东北林业大学学报, 2005, 33(3): 47–48] 相似文献
8.
Calculating aggregation index by the sample-plot data used to lead to computing error due to the existence of a boundary effect.
Here, we suggest a method for adjusting boundary effect in the analysis of spatial patterns at different stages of development
of the broad-leaved Korean pine forest. This method is good for the reasonable management and biological control of the forests.
The total station was used to sample the relative coordinates data at four corners of the temporary sample plot and of each
tree in the field. Based on the sampling data, a correct approach to the boundary effect on aggregation index was put forward
to the spatial pattern analysis of the broad-leaved Korean pine forest in its different stages of development. The results
showed that the forest trees grew in a clumped pattern in the stage dominated by the pioneer trees, and that the trees were
distributed in a random pattern in the stage dominated by the companion trees or in the mature stage. The spatial pattern
of the broad-leaved Korean pine forest changing from clumped to random distribution is influenced by biological characteristic,
the adaptive strategy of tree species and the natural disturbance in its entire development.
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Translated from Journal of Nanjing Forestry University, 2005, 29(3): 57–60 [译自: 南京林业大学学报, 2005, 29(3): 57–60] 相似文献
9.
In order to reduce the density of wood-based composites without causing a deterioration of their mechanical properties, we
studied the process of manufacturing wood-based composites. A combination of polymer foaming technology and flat hot-pressing
technology was used. The microscopic structure of the various wood-based composites was analyzed with a scanning electron
microscope (SEM). Modulus of rupture (MOR), modulus of elasticity (MOE), impact strength, and thickness expansion rate of water sorption (TS) were all measured. The results showed that fibers loosely interweave, and fibers had been connected by micropore. They also
showed that spaces between fibers had big micropore structure. MOR, MOE and impact strength were the highest among three levels of ratio. When the total content of resin and foaming agent were
20% by weight, TS was higher. A hot-pressing temperature of 120°C was optimal. At the low temperatures of 80°C, the foaming process was uncompleted.
At a higher temperature, micropores burst at a certain pressure. Based on the variance analysis and maximum difference analysis,
a significance test shows that the optimum conditions for the total content of resin and foaming agent is 20% by weight, with
a hot pressing temperature of 120°C for 15 min. Under these conditions, the properties of wood-based foaming composites all
achieved the industry standard.
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Translated from Journal of Beijing Forestry University, 2007, 29(3): 154–158 [译自: 北京林业大学学报] 相似文献
10.
Jiying Song Youqing Luo Juan Shi Xiaosu Yan Weiping Chen Ping Jiang 《Frontiers of Forestry in China》2006,1(4):460-463
In November 2003 and June 2004, the insect borers and their spatial distribution within Pinus massoniana were investigated in Zhoushan City, in East China’s Zhejiang Province, where pine wood nematode (Bursaphelenchus xylophilus) are typically found. The niche width, proportional similarity of niche and the niche overlap of dominant species of dying
trees were computed. Results show that five insect species infect and damage Pinus massoniana, which had been infected by pine wood nematodes, among which four are wood boring beetles and one termite. Species within
host trees vary from winter to summer and all the species have their own niche width, proportional similarity of niche and
the niche overlap. They can achieve competitive equilibrium and coexistence according to their biological characteristics
and life habits.
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Translated from Journal of Beijing Forestry University, 2005, 27(6): 108–111 [译自: 北京林业大学学报, 2005, 27(6): 108–111] 相似文献
11.
A preliminary study of the hydrological effects of forest litter and soils in the Simianshan Mountains was carried out. Results
indicate that the annual accumulation of different forest litters is about 6.80–20.21 t/hm2 and the maximum water carrying capacity ranges from 1.8 to 4.6 mm. Among them the water carrying abilities of the litter
of Lithocarpus glabra and natural deciduous forests are larger than that of Pinus massoniana. A power function relationship exists between the accumulated water-carrying volume and time. An investigation of the physical
properties shows that forest soils, to a depth of 1 m, have a powerful water-carrying ability, varying from 7.84 to 18.87
mm. Non-linear regression analysis shows that the soil infiltration rate is significantly correlated with time.
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Translated from Journal of Beijing Forestry University, 2005, 27(1): 33–37 [译自: 北京林业大学学报] 相似文献
12.
The growth process of natural poplar-birch forests 总被引:1,自引:0,他引:1
With a combination of permanent and temporary sample plots, we investigated the growth conditions of natural poplar-birch
forests. The forests were divided into four site classes, using statistical and analytical techniques in a quantitative model,
in descending order where site class I was the best. On this basis, the growth of natural poplar-birch forests in the different
site classes was studied. The growth processes of height and diameter at breast height were divided into three stages: a fast
growing period, a stable growing period and a slow growing period. Results of this study provide a theoretical basis for the
directive cultivation of natural poplar-birch forests.
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Translated from Journal of Northwest Forestry University, 2005, 33(5): 9–12 [译自: 东北林业大学学报, 2005, 33(5): 9–12] 相似文献
13.
According to the requirements of the conversion of farmland to forests project (CFFP), we investigated the vegetation factors
and environmental factors from more than 6,105 sub-compartments in Liangcheng County, Inner Mongolia by using the Matlab,
analytic hierarchy process (AHP), and the hierarchical cluster method (HCM). The site conditions were classified quantitatively.
The results show that CFFP at this site comprises five site-type groups and 19 site types. A quantitative site classification
system method has been established in this paper.
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Translated from Journal of Beijing Forestry University, 2005, 27(6) [译自: 北京林业大学学报, 2005, 27(6)] 相似文献
14.
Carbon storage of artificial forests in rehabilitated lands in the upper reaches of the Yellow River
Jianzhong Hu 《Frontiers of Forestry in China》2006,1(3):268-276
We studied 10-to 27-year-old artificial forests on rehabilitated lands in the upper reaches of the Yellow River with the objective
of comparing the carbon densities of various artificial and natural forests. Under artificial plantations, the vegetation
layer (including roots) had a mean carbon density of 111.3 t/hm2, the litter layer a density of 5.1 t/hm2, and the soil layer a density of 64.9 t/hm2. These values accounted for 28.6%, 13.8%, and 61.0% of their respective counterparts in the natural secondary forests under
the same site conditions in the region. The ratios of carbon density among vegetation, litter, and soil pools were 39.6:1.8:58.6
for artificial forests and 57.4:2.7:39.9 for natural forests. The carbon densities of the vegetation and litter layers increased
exponentially with forest age. The total carbon density ratios were also increasing gradually. Although the mean total carbon
density of the artificial forests in the rehabilitated lands was 281.2 t/hm2 in the experimental area, it accounted for only 41.5% of the carbon density of the natural secondary forests (677.4 t/hm2). The annual increase in total carbon density of artificial forests was as high as 15.2 t/hm2, which was 11.7% more than that of natural forests and 6.8 times higher than that (1.95 t/hm) of artificial forests in the
entire country as measured during 1994–1998. This indicates that growth and carbon storage capacity of artificial forests
in the rehabilitated lands were higher than those of forests on the barren hills and the secondary forests. We concluded that
the conversion project from croplands to forests and grasslands based on scientific principles is very important in the formation
of carbon sinks for reducing greenhouse effects.
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Translated from Journal of Beijing Forestry University, 2005, 27(6): 1–8 [译自: 北京林业大学学报, 2005, 27(6): 1–8] 相似文献
15.
To meet the demand of automatic pruning machines, this paper presents a new method for dynamic automatic identification of
standing tree limbs and capture of the digital images of Platycladus orientalis. Methods of computer vision, image processing and wavelet analysis technology were used to compress, filter, segment, abate
noise and capture the outline of the picture. We then present the arithmetic for dynamic automatic identification of standing
tree limbs, extracting basic growth characteristics of the standing trees such as the form, size, degree of bending and their
relative spatial position. We use pattern recognition technology to confirm the proportionate relationship matching the database
and thus achieve the goal of dynamic automatic identification of standing tree limbs.
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Translated from Journal of Beijing Forestry University, 2005, 27(4) [译自: 北京林业大学学报, 2005, 27(4)] 相似文献
16.
Scots pine sapwood (Pinus sylvestris L.) and Douglas fir heartwood (Pseudotsuga menziesii Franco) specimens were exposed in double layer field trials at 23 different European test sites under different exposure
conditions (in total 27 test sets). The material climate in terms of wood moisture content (MC) and wood temperature was automatically
monitored over a period of up to 7 years and compared with the progress of decay. The overall aim of this study was to establish
dose–response relationships between climate factors and decay as a basis for the service life prediction of wood. The “Scheffer
Climate Index” based on weather data collected at official meteorological stations at the different test sites poorly correlated
with the corresponding decay progress and was therefore not a suitable tool for estimating site-specific decay potential.
In contrast, the use of the combined material climatic parameters MC and wood temperature led to a feasible dose–response
function and turned out to be a useful basis for service life prediction of wood. 相似文献
17.
The interactions between pine wood nematode and three bacterium strains isolated from the nematode, Bursaphelenchus xylophilus, which are two strong pathogenic bacterium strains, Pseudomonas fluorescens GcM5-1A and Pseudomonas putida ZpB1-2A and a weak-pathogenic bacterium strain, Pantoea sp. ZM2C, were studied. The result showed that the strong-pathogenic GcM5-1A strain and ZpB1-2A strain significantly increased
fecundity, reproduction rate, and the body volume of the adult nematode. Meanwhile, pine wood nematodes significantly promoted
reproduction of the two strong-pathogenic bacterium strains. However, the weak-pathogenic bacterium strain, ZM2C, completely
inhibited reproduction of pine wood nematodes. Aseptic pine wood nematodes significantly inhibited reproduction of the strain
ZM2C. The results indicated that mutualistic symbiosis exists between pine wood nematodes and the two pathogenic bacteria
it carries. The phenomenon showed that the pathogenic bacteria carried by the nematode were not accidentally contaminated,
but rather had existed as symbionts of the nematode with which it had coevoluted over a long period. The role of mutualistic
symbiosis in the process of pine wilt disease was also discussed.
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Translated from Journal of Nanjing Forestry University, 2005, 29(3): 1–4 [译自: 南京林业大学学报, 2005, 29(3): 1–4] 相似文献
18.
Fractal theory, used to study natural figures and images with self-similarity but without characteristic lengths, offers an
effective tool to investigate quantitatively the complex systems such as soil. In this paper, we have discussed about our
study of the fractal features of the subalpine coniferous forests, soil particles, and microaggregates under different intensities
of anthropogenic disturbances in the Miyaluo area of west Sichuan and investigated the effects of the disturbances on the
forest soils attributed to different fractal dimensions. The study introduces a new way to investigate the recovery and reestablishment
of subalpine coniferous forests.
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Translated from Chinese Journal of Ecology, 2005, 24(8): 878–882 [译自: 生态学杂志, 2005, 24(8): 878–882] 相似文献
19.
Jianying Xu Ragil Widyorini Hidefumi Yamauchi Shuichi Kawai 《Journal of Wood Science》2006,52(3):236-243
Binderless fiberboards with densities of 0.3 and 0.5 g/cm3 were developed from kenaf core material using the conventional dry-manufacturing process. The effects of steam pressure (0.4–0.8
MPa) and cooking time (10–30 min) in the refining process, fiber moisture content (MC) (10%, 30%), and hot-pressing time (3–10
min) on the board properties were investigated. The results showed that kenaf core binderless fiberboards manufactured with
high steam pressure and long cooking time during the refining process had high internal bond (IB) strength, low thickness
swelling (TS), but low bending strength values. The binderless fiberboards made from 30% MC fibers showed better mechanical
and dimensional properties than those from air-dried fibers. Hot-pressing time was found to have little effect on the IB value
of the binderless board at the refining conditions of 0.8 MPa/20 min, but longer pressing time resulted in lower TS. At a
density of 0.5 g/cm3, binderless fiberboard with the refining conditions of 0.8 MPa/20 min recorded a modulus of rupture (MOR) of 12 MPa, modulus
of elasticity (MOE) of 1.7 GPa, IB of 0.43 MPa, and 12% TS under the optimum board manufacturing conditions.
Part of this article was presented at the 54th Annual Meeting of the Japan Wood Research Society, Hokkaido, August 3–5, 2004 相似文献
20.
Preliminary study on the characteristics of tactility of wood by physiological index HRV 总被引:1,自引:0,他引:1
We used heart rate variability (HRV), an electrophysiological index, to investigate the changes of the sympathetic and parasympathetic
nervous systems of people when they were in contact with wood and other materials, in a time-domain, a frequency-domain, and
by means of nonlinear dynamics. Our aim was to discover the relations among thermal parameters of different kinds of material,
human physiological feedbacks, and psychological perceptions. It shows that the activity of the sympathetic nervous system
when in contact with wood increased no more than when in contact with metal and ceramic materials, while the activity of the
parasympathetic nervous system weakened less than when in contact with these materials. The time taken by the sympathetic
and parasympathetic nervous systems to revert to their normal state after contact with cloth and wood was shorter than that
after contact with metal and ceramic. A subjective survey, by SD method, showed that the tactility of wood was favorable and
people preferred wood to other kinds of material. Correlation analysis’ results showed that there was a close correlation
among the HRV indices, human psychological emotion ratings, and thermal parameters of the different kinds of materials. The
experiment proves that the effect of wood on our autonomous nervous system is slightly better than that of other materials
except for cloth. Wood does not damage people’s health.
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Translated from Journal of Northeast Forestry University, 2005, 33(2): 29–31 [译自: 东北林业大学学报, 2005, 33(2): 29–31] 相似文献