Energy and carbon dioxide (CO2) balance of logging residues as alternative energy resources: system analysis based on the method of a life cycle inventory (LCI) analysis

Using the method of a life cycle inventory (LCI) analysis, the energy balance and the carbon dioxide (CO₂) emission of logging residues from Japanese conventional forestry as alternative energy resources were analyzed over the entire life cycle of the residues. The fuel consumption for forestry machines was measured in field experiments for harvesting and transporting logging residues at forestry operating sites in Japan. In addition, a total audit of energy consumption was undertaken. It involved an assessment of materials, construction, and the repair and maintenance of forestry machines as well as the costs associated with an energy-conversion plant. As a result, the ratio of energy output to input was calculated to be 5.69, indicating that the system examined in this study could be feasible as an energy production system. The CO₂ emission per MWh_e (e: electricity) of the biomass-fired power generation plant was calculated to be 61.8kgCO₂/MWh_e, while that of coal-fired power generation plants in Japan is 960kgCO₂/MWh_e. Therefore, the reduction in the amount of CO₂ emission that would result from replacing coal with biomass for power generation by as much as 3.0 million dry-t/year of logging residues in Japan was estimated to be 1.66 million tCO₂/year, corresponding to 0.142% of the national CO₂ emission. This study provides evidence that Japan could reduce its domestic CO₂ emission by using logging residues as alternative energy resources.     

Lysimeter study on the use of biodrainage to control waterlogging and secondary salinization in (canal) irrigated arid/semi-arid environment

The study describes the capacity of trees to control the rise in water table and thus prevent the formation of waterlogged soils and development of secondary salinization in canal irrigated areas. It was conducted in RCC lysimeters of 1.2 m dia. and 2.5 m depth filled with sandy loam alluvial soil (Typic Ustochrept), with provisions to maintain water table depth at 1, 1.5 and 2 m from the surface and groundwater salinity at 0.4, 3, 6, 9 and 12 dS m-1. The amount of water biodrained by eucalyptus (Eucalyptus tereticornis) and bamboo (Bambusa arundinacea) at the given water table depths and groundwater salinity levels was monitored over four years by daily measuring the water needed for maintaining the water table. The trees continued to absorb and transpire water throughout the year, the capacity being more in summer and rainy than that was in the winter season. The eucalyptus plant could biodrain 2880, 5499, 5518 and 5148 mm of water in the first, second, third and fourth year of study period, from non-saline groundwater and a water table depth of 1.5 m. The amount of water biodrained was more at 1.5 m as compared to 1 and 2 m water table depths. The biodrainage capacity of trees was significantly affected by the salinity of the groundwater. However, even at salinity of 12 dS m-1, the eucalyptus plant biodrained 53% of that under non-saline conditions. It was calculated that biodrainage could control water table rises upto 1.95, 3.48, 3.76 and 3.64 m in first, second, third and fourth year, respectively. The secondary salinity developed in the root zone, upto 45 cm depth, did not exceed 4 dS m-1 even at water table depth of 1 m with salinity of 12 dS m-1. The volume of water biodrained by bamboo increased with time and could control water table rises upto 1.09, 1.86, 2.46 and 2.96 m in first, second, third and fourth year of growth, respectively.This study indicates that due to high transpiration capacity and an ability to extract water from deeper layers containing saline groundwater, the trees can control the rise in water table in irrigation command areas and prevent the formation of waterlogged and eventually the saline wastelands.     

Controlled water table management as a strategy for reducing salt loads from subsurface drainage under perennial agriculture in semi-arid Australia

Recent community based actions to ensure the sustainability of irrigation and protection of associated ecosystems in the Murrumbidgee Irrigation Area (MIA) of Australia has seen the implementation of a regional Land and Water Management Plan. This aims to improve land and water management within the irrigation area and minimise downstream impacts associated with irrigation. One of the plan objectives is to decrease current salt loads generated from subsurface drainage in perennial horticulture within the area from 20 000 tonnes/year to 17 000 tonnes/year. In order to meet such objectives Controlled Water table Management (CWM) is being investigated as a possible ‘Best Management Practice’, to reduce drainage volumes and salt loads.During 2000–2002 a trial was conducted on a 15 ha subsurface drained vineyard. This compared a traditional unmanaged subsurface drainage system with a controlled drainage system utilizing weirs to maintain water tables and changes in irrigation scheduling to maximize the potential crop use of a shallow water table. Drainage volumes, salt loads and water table elevations throughout the field were monitored to investigate the effects of controlled drainage on drain flows and salt loads.Results from the experiment showed that controlled drainage significantly reduced drainage volumes and salt loads compared to unmanaged systems. However, there were marked increases in soil salinity which will need to be carefully monitored and managed.     

钢板弹簧疲劳分析

传统的钢板弹簧强度分析中,多是借助简化的力学模型,基于材料力学的小挠度梁的线弹性理论进行计算,计算中的假设条件和计算方法与钢板弹簧实际情况不尽相符,计算结果存在误差。在钢板弹簧的结构应力计算基础上,通过建立钢板弹簧装配及加载状态的精确有限元模型,并考虑片间的非线性接触,在交变载荷作用下,计算得到钢板弹簧接近实际工况的应力循环,然后利用其S N曲线,基于Miner线性累计损伤准则计算其疲劳寿命。通过钢板弹簧的实际疲劳试验,验证了模型计算结果的正确性。     

杉木人工林生长过程表编制的研究*

利用近些年来在南方１４省（区）有关单位搜集的杉木人工林（实生）标地４４６５块材料，以杉木带、区及地位指数表为分类基础，编制了５组杉木人工林生长过程表（南带，北带及中带东区、中区、西区各编一组）。各表标准差大部分在±５％以下，最大不超过±７．８％。并根据各带、区生长过程表，提出经营意见及间伐、主伐年龄。     

龙山林区天敌对马尾松毛虫抑制作用的研究*

龙山林场松毛虫天敌的种类繁多,从蜘蛛、昆虫、病菌到鸟类,构成一个极其复杂的天敌综合体。从两年四代生命表中可清楚地看出天敌的作用。在各类死亡因子中,最主要的是幼虫期的捕食性天故和其他一些死亡因子,所造成的死亡率平均为78％,根据天敌作用的系统考查,初步认为生物因子是这个周期(1984—1985年)松毛虫虫口下降的主导因子。     

Does <Emphasis Type="Italic">Puccinia hemerocallidis</Emphasis> regularly host-alternate between <Emphasis Type="Italic">Hemerocallis</Emphasis> and <Emphasis Type="Italic">Patrinia</Emphasis> plants in Japan?

Daylily rust fungus, Puccinia hemerocallidis, was proven to host-alternate between a wild daylily, Hemerocallis fulva var. longituba, and a patrinia, Patrinia villosa. No proof was obtained for the early belief that the fungus is pathogenic to plantainlilies, Hosta species, in addition to daylilies, Hemerocallis species. The fungus seems to alternate regularly between daylilies and patrinias in Japan because most daylily species are deciduous, and a vegetatively reproducing stage of the pathogen does not seem capable of successfully overwintering free of the living host tissue.     

山东省107-杨树地位指数表的编制

地位指数表是评价立地质量的重要指标之一。本文应用采集的解析木资料,选用6个导向曲线模型对标准地内平均优势木的树干解析资料进行拟合。由拟合结果确定Richards函数为最佳导向曲线模型。在分析杨树高生长在各指数级间的多形特征的基础上,建立了多形地位指数模型,并编制了多形地位指数表。经检验表明,编制的多形地位指数表具有较好的精度。     

蓝藻介导磁聚物化学强化一级处理低浓度生活污水的研究

通过壳聚糖-超纯磁铁矿粉磁聚物对低浓度生活污水化学强化一级处理并利用磁场将絮体收集实验得出,引入蓝藻充当媒介,可使絮体大而密实,有助于水体污染物的去除。引入超纯磁铁矿粉,可使形成的絮体带有强磁性,便于借助外磁场快速移出水体,从而为固液分离提供一种新的工艺思路。     

灌溉对土壤水分分布和潜水蒸发的影响

通过室内土柱试验,对3种灌水处理条件下不同地下水埋深土壤中的水分分布和潜水蒸发规律进行了分析。结果表明,灌溉制度和地下水埋深对潜水蒸发影响较大。在同一水位下,总灌水量相同,灌水频率不同时,随灌水频率增加,潜水蒸发量显著减少;在同一水位下,低灌水频率土壤随次灌水量增加潜水蒸发减少,且水位越深,潜水蒸发量减少越大,水位越浅,潜水蒸发量减少越小。