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枯萎病菌不同专化型镰刀菌酸的产生数量与菌丝生长的相互关系 被引量:3
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作者 姚艳平 王建明 +1 位作者 郭强 武扬 《山西农业大学学报(自然科学版)》 CAS 2002年第3期231-233,252,共4页
在改良的理查德培养基中 ,通过对引起枯萎病的五种不同专化型的尖孢镰刀菌镰刀菌酸的产生数量与菌丝生长间的相互关系进行研究 ,结果表明 ,不同专化型的枯萎病菌镰刀菌酸产生的早晚及产生数量明显不同 ,而且其菌丝生长情况也各异。尖孢... 在改良的理查德培养基中 ,通过对引起枯萎病的五种不同专化型的尖孢镰刀菌镰刀菌酸的产生数量与菌丝生长间的相互关系进行研究 ,结果表明 ,不同专化型的枯萎病菌镰刀菌酸产生的早晚及产生数量明显不同 ,而且其菌丝生长情况也各异。尖孢镰刀菌黄瓜专化型和翠菊专化型的镰刀菌酸的产生数量与菌丝生长的相互关系较为密切。 展开更多
关键词 枯萎病菌 专化型 镰刀菌酸 产生数量 菌丝生长 作物 相互关系
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Evaluation of straightening capacity of plate roll straightener 被引量:1
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作者 王勇勤 刘志芳 严兴春 《Journal of Central South University》 SCIE EI CAS 2012年第9期2477-2481,共5页
Straightening machine is widely used for improving the quality of the defective mild steel plates.In general,the capacity of straightening machine is affected by material properties,the initial shape of the incoming p... Straightening machine is widely used for improving the quality of the defective mild steel plates.In general,the capacity of straightening machine is affected by material properties,the initial shape of the incoming plate and the plastic ratio.The mechanics model describing the capacity of the machine was developed.The deviation of the straightening capacity curves was studied.Then,the presented model was evaluated by comparative study to filed production data.Finally,the influences of overstretch,straightening speed,strengthening coefficient,elastic modulus,width of the plate on the straightening capacity were studied.It is convenient to determine whether the plate can be straightened or not by a series of straightening capacity curves.The straightening speed,width of the plate and elastic modulus of the material are more sensitive to the straightening capacity than the strengthening coefficient. 展开更多
关键词 plastic ratio straightening capacity strengthening factor PLATE
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Multi-objective optimization of rolling schedule based on cost function for tandem cold mill 被引量:4
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作者 陈树宗 张欣 +3 位作者 彭良贵 张殿华 孙杰 刘印忠 《Journal of Central South University》 SCIE EI CAS 2014年第5期1733-1740,共8页
In terms of tandem cold mill productivity and product quality, a multi-objective optimization model of rolling schedule based on cost fimction was proposed to determine the stand reductions, inter-stand tensions and r... In terms of tandem cold mill productivity and product quality, a multi-objective optimization model of rolling schedule based on cost fimction was proposed to determine the stand reductions, inter-stand tensions and rolling speeds for a specified product. The proposed schedule optimization model consists of several single cost fi.mctions, which take rolling force, motor power, inter-stand tension and stand reduction into consideration. The cost function, which can evaluate how far the rolling parameters are from the ideal values, was minimized using the Nelder-Mead simplex method. The proposed rolling schedule optimization method has been applied successfully to the 5-stand tandem cold mill in Tangsteel, and the results from a case study show that the proposed method is superior to those based on empirical formulae. 展开更多
关键词 tandem cold mill multi-object optimization rolling schedule cost function simplex algorithm
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Domestication Test of Halopegia azurea (Karl Moritz Schumann) (Marantaceae): Preliminary Study on the Rhizome Cuttings
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作者 Marie Marguerite Mbolo Abada Jean Ernest Mballa Bimi Josseline Landry Douandju Tsonang Pierre Abe 《Journal of Environmental Science and Engineering(A)》 2015年第1期21-29,共9页
In order to domesticate H. azurea (Halopegia azurea), acclimatization of rhizome's cuttings and young shoots in farms was tested at Nkol Evodo village from February 2012 to June 2012. The best substrate for propaga... In order to domesticate H. azurea (Halopegia azurea), acclimatization of rhizome's cuttings and young shoots in farms was tested at Nkol Evodo village from February 2012 to June 2012. The best substrate for propagation was assessed: (0) wetland; (1) sand/wetland; (2) sawdust/wetland; (3) sand/sawdust/wetland. Young shoots' growth was observed in situ for 8 weeks. A significant difference (P 〈 0.05) was observed in the appearance of young shoots and leaves in nursery. The highest average number of young shoots and leaves (0.62 ± 0.09) was found in substrates 0 and 1, the lowest (0.31 ± 0.08) in substrate 3. Substrate 3 showed the lowest number of young leaves (0.41 ± 0.16) and substrate 2 the highest (0.97 ±0.24). A significant difference in the mortality rate of cuttings (P 〈 0.05) was observed: 68.75% and 53.12% in substrates 2 and 3, respectively. On farm, new leaves and young shoots' appearance showed a highly significant difference. Plants growing in substrates 2 and 3 showed the highest number of leaves. New shoots developed only in plants growing in substrates 0 and 1. These results suggest that it is possible to domesticate H. azurea for leaves' production in quantity and quality, and open up better opportunities for its cultivation. 展开更多
关键词 H. azurea DOMESTICATION CUTTINGS substrate farm.
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Study and application on the evaluation method of porous formation for long-term waterflooding sand reservoir 被引量:1
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作者 Wang Changjiang Jiang Hanqiao +2 位作者 Chen Minfeng Geng Zhanli Liu Pengfei 《Engineering Sciences》 EI 2009年第3期88-92,共5页
Nine targets which stand both for the static characteristic of produced formations and the dynamic parameter of wells including the average permeability,variation coefficient of permeability,moving capability,remainin... Nine targets which stand both for the static characteristic of produced formations and the dynamic parameter of wells including the average permeability,variation coefficient of permeability,moving capability,remaining recoverable reserves,coefficient of flooding,daily oil production,increasing rate of water cut,cumulative liquid production per unit meter and efficiency index of oil production are selected as the evaluation indexes,a novel model to evaluate the porous formations in long-term waterflooding sand reservoir was established by using the support vector machine and clustering analysis. Data of 57 wells from Shentuo 21 block Shengli oilfield was analyzed by using the model. Four kinds of formation groups were gained. According to the analysis result,different adjustment solutions were put forward to develop the relevant formations. The Monthly oil production increased 7.6 % and the water cut decreased 8.9 % after the adjusted solutions. Good results indicate that the learning from this method gained will be valuable adding to other long-term waterflooding sand reservoirs in Shengli oilfield and other similar reservoirs worldwide. 展开更多
关键词 long-term waterfiooding reservoir support vector machine clustering formation evaluation adjustment solution
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Study on the Refineries' Energy Efficiency Based on SFA- Model
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作者 Liu Siwei Shen Hao 《International Journal of Technology Management》 2013年第6期31-34,共4页
The study on the enterprise's energy efficiency is one of the most important fields of energy efficiency research. Most studies used DEA and aggregate data to estimate the energy efficiency of enterprises. In this st... The study on the enterprise's energy efficiency is one of the most important fields of energy efficiency research. Most studies used DEA and aggregate data to estimate the energy efficiency of enterprises. In this study, based on Cobb-Douglas production function, we make a SFA model which takes the energy input and CO2 emission into account. By using the SFA model, we calculate the refineries' total-factor energy efficiency with Sinopec refineries' micro-data from 2004 to 2009. Meanwhile, we do empirical study on the factors which influence the energy efficiency. In the last, we put forward some advices so as to improve energy efficiency. 展开更多
关键词 REFINERY total-factor energy efficiency SFA model CO2 emission
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Influence of variables in deep drawing of AA 6061 sheet 被引量:8
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作者 S.RAJU G.GANESAN R.KARTHIKEYAN 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2010年第10期1856-1862,共7页
Deep drawing is one of the most important processes for forming sheet metal parts.It is widely used for mass production of cup shapes in automobile,aerospace and packaging industries.Cup drawing,besides its importance... Deep drawing is one of the most important processes for forming sheet metal parts.It is widely used for mass production of cup shapes in automobile,aerospace and packaging industries.Cup drawing,besides its importance as forming process,also serves as a basic test for the sheet metal formability.The effect of equipment and tooling parameters results in complex deformation mechanism.Existence of thickness variation in the formed part may cause stress concentration and may lead to acceleration of damage.Using TAGUCHI's signal-to-noise ratio,it is determined that the die shoulder radius has major influence followed by blank holder force and punch nose radius on the thickness distribution of the deep drawn cup of AA 6061 sheet.The optimum levels of the above three factors,for the most even wall thickness distribution,are found to be punch nose radius of 3 mm,die shoulder radius of 8 mm and blank holder force of 4 kN. 展开更多
关键词 deep drawing aluminium alloy thickness distribution signal to noise ratio
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An Econometric Analysis of Cotton Production Technologies in Harran Plain, Turkey: Translog versus Cobb-Douglas Functions
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作者 T. Isgin R. Ozel +1 位作者 A. Bilgic S. Ipekcioglu 《Journal of Agricultural Science and Technology(B)》 2011年第3期420-427,共8页
This research explores the question of how the three production factors, capital, labor, and land may impact the current level of cotton output on the Harran Plain, a major cotton production area in Turkey. The object... This research explores the question of how the three production factors, capital, labor, and land may impact the current level of cotton output on the Harran Plain, a major cotton production area in Turkey. The objective of this paper is to estimate a Translog production function and compare the results to those from a Cobb-Douglas specification. Nested tests we performed resulted in the conclusion that the constant returns to scale, weak separability and Cobb-Douglas hypotheses are all satisfied. Thus the Cobb-Douglas specification is a superior functional form yielding results more robust than those from the translog model. Dwelling on Cobb-Douglas estimation results, farm size is found the most influential variable determining cotton output, followed by the variable representing capital as the second influential. Results also demonstrate that the returns-to-scale parameter calculated for this sample is not statistically different from unity, suggesting that cotton production technology in this region exhibits constant returns to scale. This result is consistent with current literature findings that render support to an inverse relationship between farm size and productivity in developing countries. 展开更多
关键词 Cotton translog model cobb-douglas model weak separability TURKEY constant returns to scale.
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ENERGY FLOW OF BELLAMYA AERUGINOSA IN A SHALLOW ALGAL LAKE, HOUHU LAKE (WUHAN, CHINA)
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作者 闫云君 梁彦龄 王洪铸 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2001年第3期243-248,共6页
The energy budget of Bellamya earuginosa in a shallow algal lake, Houhu Lake (Wuhan, China) was investigated by the measurement of flesh production (32.8kJ/(m 2·a)), egestion (337.7 kJ/(m 2·a)), metabolism (... The energy budget of Bellamya earuginosa in a shallow algal lake, Houhu Lake (Wuhan, China) was investigated by the measurement of flesh production (32.8kJ/(m 2·a)), egestion (337.7 kJ/(m 2·a)), metabolism (246.7 kJ/(m 2·a)), and estimation of excretion (21.4kJ/(m 2·a)). The net growth efficiency of the species is about 10.9%, which accords with the generally reported value for gastropods. In addition, the relationships between starvation respiration ( R , mgO 2/(Ind·d)), body weight ( Wd , mg in dry wt) and temperature ( T , ℃) were also determined. The regression equation R =0.044 Wd 0.537 e 0.061T was obtained by the least square method, The measured SDA of the species is 26.51% of its gross metabolism. 展开更多
关键词 Houhu Lake energy flow Bellamya aeruginosa
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Design of intrinsically safe power supply 被引量:3
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作者 LI Rui-jin JIN Lin 《Journal of Coal Science & Engineering(China)》 2012年第4期443-448,共6页
Aiming to make a high power direct current supply safely used in coal mine production, this paper made a deep research on characteristics of intrinsically safe power supply, using the mathematical model established ac... Aiming to make a high power direct current supply safely used in coal mine production, this paper made a deep research on characteristics of intrinsically safe power supply, using the mathematical model established according to coal mine intrinsic safety standards. It provides theory support for the application of high power intrinsically safe power supply. The released energy of output short circuit of switch power supply, and the close related factors that influence the biggest output short-circuit spark discharge energy are the theoretical basis of the power supply. It is shown how to make a high power intrinsically safe power supply using the calculated values in the mathematical model, and take values from intrinsically safe requirements parameters scope, then this theoretical calculation value can be developed as the ultimate basis for research of the power supply. It gets the identification method of intrinsically safe from mathematics model of intrinsically safe power supply characteristics study, which solves the problem of theory and application of designing different power intrinsically safe power supply, and designs a kind of high power intrinsically safe power supply through this method. energy, flyback 展开更多
关键词 intrinsically safe circuit switching power supply output short circuit discharge characteristics output short circuit release
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Comparative Analysis of Energy Efficiency in Wheat Production in Different Climate Conditions of Europe
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作者 Janusz Gotaszewski Marcel van der Voort +3 位作者 Andreas Meyer-Aurich Fatima Baptista Athanasios Balafoutis Hannu Juhani Mikkola 《Journal of Agricultural Science and Technology(B)》 2014年第8期632-640,共9页
This paper presents results concerning energy efficiency of wheat production considered in the context of specific energy input variation in different climatic conditions of Europe as well as case studies on implement... This paper presents results concerning energy efficiency of wheat production considered in the context of specific energy input variation in different climatic conditions of Europe as well as case studies on implementation of selected energy saving measures in practice. The source data collected from the six european union (EU) countries represent five agricultural regions of continental Europe and three climates: continental, temperate and Mediterranean. The life cycle assessment (LCA) methodology was applied to analyze the data excluding of pre-farm gate activities. The total primary energy consumption was decomposed into main energy input streams and it was regressed to yield. In order to compare energy efficiency of wheat production across the geographical areas, the data envelopment analysis (DEA) was applied. It was shown that the highest wheat yield (6.7 t/ha to 8.7 t/ha) at the lowest specific energy input (2.08 GJ/t to 2.56 G J/t) is unique for temperate climate conditions. The yield in continental and Mediterranean climatic conditions is on average lower by 1.3 t/ha and 2.7 t/ha and energy efficiency lower by 14% and 38%, respectively. The case studies have shown that the energy saving activities in wheat production may be universal for the climatic zones or specific for a given geographical location. It was stated that trade-offs between energy, economic, and environmental effects, which are associated with implementation of a given energy saving measure or a set of measures to a great extent depend on the current energy efficiency status of the farm and opportunity for investment, which varies substantially across Europe. 展开更多
关键词 WHEAT energy efficiency trade-off analysis
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Biodiesel Production from Crude Jatropha curcas L.Oil with Trace Acid Catalyst 被引量:1
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作者 刘颖颖 鲁厚芳 +3 位作者 蒋炜 李东升 刘世界 梁斌 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2012年第4期740-746,共7页
Biodiesel produced from crude Jatropha curcas L.oil with trace sulfuric acid catalyst(0.02%-0.08% oil) was investigated at 135-184 ℃.Both esterification and transesterification can be well carried out simultane-ously... Biodiesel produced from crude Jatropha curcas L.oil with trace sulfuric acid catalyst(0.02%-0.08% oil) was investigated at 135-184 ℃.Both esterification and transesterification can be well carried out simultane-ously.Factors affecting the process were investigated,which included the reaction temperature,reaction time,the molar ratio of alcohol to oil,catalyst amount,water content,free fatty acid(FFA) and fatty acid methyl ester(FAME) content.Under the conditions at 165 ℃,0.06%(by mass) H2SO4 of the oil mass,1.6 MPa and 20:1 methanol/oil ratio,the yield of glycerol reached 84.8% in 2 hours.FFA and FAME showed positive effect on the transesterification in certain extent.The water mass content below 1.0% did not show a noticeable effect on trans-esterification.Reaction kinetics in the range of 155 ℃ to 175 ℃ was also measured. 展开更多
关键词 free fatty acids Jatropha curcas L.oil BIODIESEL TRANSESTERIFICATION acid catalyst
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Methods Comparison for Microsatellite Marker Development:Different Isolation Methods,Different Yield Efficiency 被引量:1
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作者 ZHAN Aibin BAO Zhenmin HU Xiaoli LU Wei HU Jingjie 《Journal of Ocean University of China》 SCIE CAS 2009年第2期161-165,共5页
Microsatellite markers have become one kind of the most important molecular tools used in various researches. A large number of microsatellite markers are required for the whole genome survey in the fields of molecula... Microsatellite markers have become one kind of the most important molecular tools used in various researches. A large number of microsatellite markers are required for the whole genome survey in the fields of molecular ecology,quantitative genetics and genomics. Therefore,it is extremely necessary to select several versatile,low-cost,efficient and time-and labor-saving methods to develop a large panel of microsatellite markers. In this study,we used Zhikong scallop(Chlamys farreri) as the target species to compare the efficiency of the five methods derived from three strategies for microsatellite marker development. The results showed that the strategy of constructing small insert genomic DNA library resulted in poor efficiency,while the microsatellite-enriched strategy highly improved the isolation efficiency. Although the mining public database strategy is time-and cost-saving,it is difficult to obtain a large number of microsatellite markers,mainly due to the limited sequence data of non-model species deposited in public databases. Based on the results in this study,we recommend two methods,microsatellite-enriched library construction method and FIASCO-colony hybridization method,for large-scale microsatellite marker development. Both methods were derived from the microsatellite-enriched strategy. The experimental results obtained from Zhikong scallop also provide the reference for microsatellite marker development in other species with large genomes. 展开更多
关键词 MICROSATELLITE marker development isolation efficiency method comparison SCALLOP
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Evaluation of the individual allocation scheme and its impacts in a dynamic global vegetation model 被引量:1
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作者 SONG Xiang ZENG Xiao-Dong LI Fang 《Atmospheric and Oceanic Science Letters》 CSCD 2016年第1期38-44,共7页
The strategies of plant growth play an important role not only in ecosystem structure,but also in global carbon and water cycles.In this work,the individual carbon allocation scheme of tree PFTs and its impacts were e... The strategies of plant growth play an important role not only in ecosystem structure,but also in global carbon and water cycles.In this work,the individual carbon allocation scheme of tree PFTs and its impacts were evaluated in China with Institute of Atmospheric Physics-Dynamic Global Vegetation Model,version 1.0(IAP-DGVM1.0)as a test-bed.The results showed that,as individual growth,the current scheme tended to allocate an increasing proportion of annual net primary productivity(NPP)to sapwood and decreasing proportions to leaf and root accordingly,which led to underestimated individual leaf biomass and overestimated individual stem biomass.Such biases resulted in an overestimation of total ecosystem biomass and recovery time of mature forests,and an underestimation of ecosystem NPP and tree leaf area index in China. 展开更多
关键词 IAP-DGVM 1.0 individual allocation scheme BIOMASS carbon residence time China
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Survey and Conservation of Indigenous Fruits of Western Ghats
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作者 Prakash Chandra Tripathi Ganesan Karunkaran +1 位作者 Vadivel Sankar Rathnam Senthil Kumar 《Journal of Agricultural Science and Technology(A)》 2015年第7期608-615,共8页
Western Ghats region of India is one of the biodiversity hotspots of the world. The topography, wide rainfall variation and varied temperature conditions enable inhabitancy of several plant species. This plant wealth ... Western Ghats region of India is one of the biodiversity hotspots of the world. The topography, wide rainfall variation and varied temperature conditions enable inhabitancy of several plant species. This plant wealth is being used in various forms by tribes and natives of the area for centuries. These gain further importance due to the fact that ripe fruits serve as a source of food and medicine to tribes throughout the year. These wild fruits are source of minerals and vitamins in the diet of the rural people. The potential productivity and floristic diversity of the area have attracted the experts. There are more than 50 wild edible fruit species are available in Western Ghats region. These belong to 25 families and 38 genera. Out of the 25 families, the important ones as a source of fruits are Apocynaceae, Anacardiaceae, Euphorbiaceae, Moraceae, Sapotaceae and Sapindaceae. The fruiting period of different species ranges between two and six months. The highest number of species mature from April to May. The availability of these fruits reduces after October. Some of these fruits, such as Mangifera indica, Artocarpus heterophyllus, Carissa carandas, Emblica officinalis and Syzygium cuminii, have been given emphasis in order to identify high yield and high fruit quality clones and standardization of production technologies. The collection, conservation and utilization on some of the fruits, such as Garcinia indica and Garcinia gummigutta have started at various research organizations. Some other fruits, namely Chrysophyllum roxburghii (Family Sapotaceae), Canthium parviflora Lamk syn. Plectronia parviflora (Lam.) Bedd. (Family Rubiaceae), Elaeagnus conferta Roxbsyn, Elaeagnus latifolia L. (Family Elaeagnaceae), Securina leucopyrus syn. Flueggea leucopyrus (Family Euphorbiaceae), Elaeocarpus tuberculatus Roxb. (Family Elaeocarpaceae), Nephelium stipulacum Bedd. syn. Doratoxylon stipulatum (Family Sapindaceae) have potential for commercial cultivation. Thus, attempts were made with the objective of recording availability of these species, proximate analysis and their on farm and off farm conservation at Central Horticultural Experiment Station (CHES). Few plants were also provided to local growers on farm conservation. The continuous depletion of forest and the increasing human disturbance resulted in losses of these species. There is need to conserve these fruits for future. 展开更多
关键词 Western Ghats indigenous fruits genetic variability conservation.
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Dependence of Consumption Volume on the Labor-Force in One-Productive Models of Economic Dynamics
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作者 Sabir Isa Hamidov 《Journal of Mathematics and System Science》 2015年第3期113-117,共5页
In the work one-productive model of economic dynamics the labor-force involved in production is investigated the case when or function with constant elasticity of substitution (CES) is studied. is considered. The de... In the work one-productive model of economic dynamics the labor-force involved in production is investigated the case when or function with constant elasticity of substitution (CES) is studied. is considered. The dependence of the consumption volume on production function coincides with the Cobb-Douglas function 展开更多
关键词 One-productive models production function Cobb-Douglas function function with constant elasticity of substitution(CES).
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Quality Analysis of Dairy Herd Improvement Data from Henan Province 被引量:1
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作者 Zhen ZHANG Xiaoli REN +3 位作者 Lei YAN Yuefei YAN Fanjun GENG Yanqin SUN 《Agricultural Science & Technology》 CAS 2017年第1期151-155,188,共6页
The dairy herd improvement data from Henan Province were analyzed statistically to establish screening criteria for relevant data, thereby laying a foundation for genetic evaluation of dairy cows. With the 2 152 451 t... The dairy herd improvement data from Henan Province were analyzed statistically to establish screening criteria for relevant data, thereby laying a foundation for genetic evaluation of dairy cows. With the 2 152 451 test-day records about 155 893 Chinese Holstein dairy cows collected by the Henan Dairy Herd Improvement Center from January 2008 to April 2016, the dynamics of test times during a complete lactation, test interval during a complete lactation, days in milk (DIM) of first test-day record, daughter descendant number and herd number of bull, age at first calving and pedigree integrity rate among different years and different herd sizes were analyzed by MEANS order of SAS 9.4. In addition, the data that were applicable to genetic evaluation were screened by SQL program. The results showed that during 2008-2015, the number of cow individuals participating in DHI in Henan Province increased from 7 379 to 93 706; the test-day milk yield increased from 19.91 to 24.05 kg; the somatic cell count reduced from 411.09×10^3 to 277.08×10^3 cells/ml; the percentage of cows with DIM ranging from 5-305 d reached 70.92%; the average test times increased from 3.20 to 6.31 times; the test interval decreased from 70.22 to 33.83 d; the dairy cows with age at first calving of 25 months were dominant, accounting for 12.57%; the bulls whose daughter descendant number was 20 or more and the daughters were distributed in 10 or more farms accounted for 6.05%; the one-generation pedigree integrity rate was 82.54%; the percentage of data that could be used for genetic evaluation was screened as 20.67%, which was lower than the results of other similar studies. 展开更多
关键词 Dairy herd improvement data quality Test times Test interval DIM of first test-day record Daughter descendant number and herd number of bull age at first calving Pedigree integrity rate
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Soil Disturbance from Different Mechanised Harvesting in Hill Tropical Forest, Peninsular Malaysia
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作者 Mohd Hasmadi Ismail Norizah Kamarudin 《Journal of Environmental Science and Engineering》 2010年第1期34-41,共8页
The impacts of mechanised forest harvesting to soil physical properties are the major concern by forest managers, which have the potential to impact soil sustainability and forest productivity. Malaysia is practicing ... The impacts of mechanised forest harvesting to soil physical properties are the major concern by forest managers, which have the potential to impact soil sustainability and forest productivity. Malaysia is practicing reduce impact logging (RIL) and applying code of forest harvest practice in forest harvesting and operations for sustainable forest resources management. In 2001, a machinery called Rimbaka Timber Harvester R2020-A was introduced for timber extraction for peat swamp forest and later on the machine was introduced to the hill tropical forest as an alternative to other machines. The study aimed to evaluate soil compaction (soil cone index, soil bulk density, soil moisture content and soil pore space) by Rimbaka Timber Harvester R2020-A and crawler tractor KOMATSU D60-A. A total of five samples were randomly taken using core sampler of 50 mm height and 50 mm diameter at the beneath a lug imprint for passes 1, 4 and 8. Altogether samples were 45. The locations of sample were to the fight and left of each rut centre for both machines. Treatment effects were evaluated using analysis of variance (ANOVA). Result showed that compaction by Rimbaka machine was increased bulk density from 1.14 to 1.43 g/cc, cone index from 1.94 to 3.45 g/cm3 decreased total pore space by 43% and decreased soil moisture content by 19%. Meanwhile compaction by KOMATSU D60-A was increased bulk density from 1.2 to 1.43 g/co, cone index from 1.24 to 1.94 g/cm3 decreased soil moisture content by 11% and total pore space by 6%, respectively. The value increased rapidly as more passes increase on the track surface. The higher soil disturbance by Rimbaka machine was due to physical design and specification of the machine. This study also observed that there was significant difference in the total passes of machinery used in harvesting operation. Although Rimbaka machine is showing more effected to soil compaction, the machine is a practical alternative to avoid skid trail and reduce road density in forest area. 展开更多
关键词 Soil disturbance bulk density cone index pore space harvesting operation Rimbaka harvester system crawler tractor.
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Responses of Grassland Net Primary Productivity to Environmental Variables in Northern China
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作者 刘芳 张红旗 +1 位作者 许尔琪 康蕾 《Journal of Resources and Ecology》 CSCD 2016年第2期92-100,共9页
Various environmental factors affect net primary productivity (NPP) of grassland ecosystem. Extensive reports on the effects of environmental variables on NPP can be found in literature. However, the agreement on th... Various environmental factors affect net primary productivity (NPP) of grassland ecosystem. Extensive reports on the effects of environmental variables on NPP can be found in literature. However, the agreement on the relative importance of various factors in shaping the spatial pattern of grassland NPP has not yet been reached. Here a grassland in situ NPP database comprising 602 samples in northern China for 1980-1999 was developed based on a literature review of published biomass and forage yield field measurements. Correlation analyses and dominance analysis were used to quantify the separate and combined effects of environmental variables (climate topography and soil) on spatial variation in NPP separately. Grassland NPP ranged from 4.76 g C m-2a-1 to 975.94gCm-2a-1, showing significant variations in space. NPP increased with annual precipitation and declined with annual mean temperature significantly. Specifically, precipitation had the greatest impact on deserts, followed by steppes and meadows. Grassland NPP decreased with increasing altitude because of water limitation, and positively correlated with slope, but weakly correlated with aspect. Soil quality showed positive effects on NPP. Annual precipitation was the dominant factor affecting the spatial variability of net primary productivity, followed by elevation. 展开更多
关键词 Grassland net primary productivity Field measurements Environmental variables Dominant factor Northern China
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Related turbulent momentum and passive scalar transfer in a turbulent channel flow 被引量:1
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作者 Ahui Tian Feng Liu Yi Zhou 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2022年第10期92-106,共15页
Direct numerical simulation was carried out to investigate the correlation between the momentum and passive scalar transfer in a turbulent channel flow with Re_(τ)=u_(τ)δ/ν=180 and Pr=0.71,where u_(τ)is the frict... Direct numerical simulation was carried out to investigate the correlation between the momentum and passive scalar transfer in a turbulent channel flow with Re_(τ)=u_(τ)δ/ν=180 and Pr=0.71,where u_(τ)is the friction velocity,δis the channel half width,andνis the kinematic viscosity.The one-point and two-point energy transfer and the corresponding scalar transfer are of particular interest.There is a significant positive correlation between the one-point energy and scalar transfer,particularly near the wall,and the correlation between the two production terms is always larger than that between the other terms.By resorting to the Karman-Howarth-Monin-Hill equation and the scale-by-scale scalar transfer budget equation,we explored the two-point energy and scalar transfer at two different vertical locations(i.e.,one location close to the wall y^(+)=10 and the other location slightly away from the wall y^(+)=60).An inverse interscale transfer phenomenon of the energy and scalar is observed in the spanwise direction at y^(+)=10,which is caused by the corresponding streak stretching,whereas along the streamwise and the vertical directions a forward interscale energy and scalar transfer phenomenon is observed.The physical mechanisms(e.g.,production,dissipation,and viscous diffusion terms)contributing to the two-point energy transfer closely resemble those in the two-point scalar transfer.The intrinsic correlation between both the two-point energy and scalar transfer can find its roots in the similarity between the momentum and scalar streaks. 展开更多
关键词 Turbulence simulation Channel flow Scale-by-scale energy budget Scalar transfer
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