共查询到20条相似文献,搜索用时 62 毫秒
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孙杰 《中国环境管理干部学院学报》2006,16(3):68-69
高等学校人才培养工作水平评估,是促进高等学校改革的重大举措.评估深化了教育体制改革,强化和完善了规章制度,提高了教学质量,优化了师资队伍.档案工作是评估的基础之一,有重要的作用,同时评估对档案工作也提出了新的要求,促进了学校档案工作的发展,使其更加规范化、科学化,也提高了档案工作者的素质. 相似文献
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The paper provides a model for the cutting of reinforced concrete members with stream-line cutting tools. The model is an extended version of the energy model originally developed by Momber and Kovacevic (1995) for hydro-abrasive machining. The model allows the stepwise calculation of the energy absorbed during the cutting of the two parts of the compound - steel bar and matrix material. Hydro-abrasive cutting tests on different cementitious composites are performed in order to verify the numerical results. It is shown that the cutting process can be subdivided into four cutting stages whose locations depended on the energy locally available at the erosion site. 相似文献
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钻井液的使用和钻屑的管理 总被引:1,自引:1,他引:0
澳大利亚矿产和能源部(DME)根据所处地区的环境敏感性、钻屑处置方式和钻井液的环境性能评估钻井液的使用及其废物排放。环境性能的标准包括基液和整个钻井液的生物毒性、可生物降解性和生物累积性。申请人有责任明确活动的环境领域和可能的环境影响。油基钻井液(OBF)的芳烃含量不超过1%,附在钻屑上的基液干重限值为10%。大钻屑堆可能是海洋低水平烃类渗漏到海洋环境的来源之一,对钻屑堆的移除和处置问题,需要慎重考虑。 相似文献
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While it is a clean alternative to conventional machining using environmentally polluting cutting oils and emulsions, cryogenic machining using liquid nitrogen has been reported to increase cutting forces and shorten tool life when cutting AISI 304 austenitic stainless steel. This paper presents improved results by using an economical cryogenic cooling approach designed after studying the cryogenic properties of the stainless steel material. By injecting a small amount of liquid nitrogen to the chip-tool interface, but not to the workpiece, this approach yielded a 67% tool-life improvement at 3.82 m/s and a 43% improvement at the medium speed of 3.40 m/s when compared with conventional emulsion cooling. It improved machining productivity and reduced production cost. In this study, different cryogenic machining approaches were compared in the machining test using commercial carbide inserts. The results show the cooling approach is crucial in attaining the benefits of cryogenic machining in cutting stainless steel. 相似文献
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This study investigated the effect of inoculation of Pleurotus tuber-regium, a Nigerian white rot fungus, period of incubation, different levels of contamination on cutting fluids degradation in contaminated
soil over 30, 60, and 90 days. Control for different levels of cutting fluids was also used to compare rates of bioremediation
of the contaminant in the soil. At the end of each incubation period, the mycelia-ramified substrate was separated from the
soil layer and dried. The soil samples were analyzed for physico-chemical parameters; total petroleum hydrocarbon, lignin
content by determining the acid detergent fraction (ADF), heavy metals content of the soil using flame atomic absorption spectrophotometer,
and changes in the polyphenol oxidase and peroxidase activities were also determined after 1, 2, and 3 months. P. tuber-regium improved the nutrient status of the soil and increased enzyme activity was recorded. A reduction in the pH and heavy metal
contents of the soil at all levels of cutting fluids concentrations was detected. The lignin in the rice straw decreased from
34.50% in the control to 8.06% at 30% cutting fluids concentration after 3 months of incubation. The highest TPH loss of 30.84%
was recorded at 20% cutting fluids contamination after 3 months compared to 13.75% at the onset of the experiment. The improvement
of the nutrient contents of the soil, bioaccumulation of heavy metals, degradation of TPH, lignin, and increased activity
of polyphenol oxidase and peroxidase was due to biodegradation of the cutting fluids. 相似文献
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An experiment was conducted to determine the influence the time of brush-cutting can have on plant regrowth and attractiveness
to herbivores that browse in linear corridors. The influence of cutting time on leaf flush and senescence, shoot morphometry,
and biomass was measured for 3 consecutive years after initial brush-cutting. Results indicate that morphological and phenological
attributes of three woody deciduous plants were influenced by the timing of brush-cutting for up to 3 years after initial
cutting. Brush-cutting generally stimulated plants to produce larger than normal shoots and delay leaf senescence. The degree
to which plants were affected, however, varied with the timing of initial cutting and the species in question. Generally,
plants cut later in the year resprouted more vigorously and were taller in the third year after cutting but produced less
overall biomass than when cut earlier. In the years following brush-cutting, plants cut earlier flushed leaves earlier in
the spring but delayed leaf senescence in the fall when compared to uncut controls. Results of these trials suggest that brush-cutting
time influences plant response and several plant attributes known to influence plant attractiveness to moose and other herbivores.
We therefore recommend that roadside and railside vegetation management plans consider the influence of cutting time on plant
regrowth. Such considerations can ensure that brush is cut to reduce the attractiveness of plant regrowth in these linear
corridors, reduce the utilization of such brush by herbivores, and, as such, mitigate collision risk between motorists and
herbivores such as moose. 相似文献
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James O. Luken Steven W. Beiting Scott K. Kareth Robyn L. Kumler Jun H. Liu Craig A. Seither 《Environmental management》1994,18(2):251-255
We tested two cutting regimens (cut/spray and cut/delay spray) and four radiarc-applied herbicides (Garlon + Tordon, Accord,
Accord + Escort, and Krenite) in an Ohio power-line corridor to determine which management combination best eliminated target
species (i.e., trees) and preserved nontarget species (i.e., low shrubs, vines, perennial herbs, and grasses).
When spraying was delayed after cutting, the herbicide with the least impact on nontarget species (Krenite) also was least
efficient at killing target trees. Spraying soon after cutting improved tree-killing efficiency of several herbicides, but
it also increased the negative impact on nontarget species. The herbicide with the most consistent tree-killing ability (Accord
+ Escort) had the most impact on nontarget species.
Because none of the herbicide/cutting treatments performed ideally, resource managers must decide the acceptable impact on
nontarget species when considering herbicide use. Future success of herbicides as part of an integrated succession management
approach requires more selective application methods and formulations so that target effects can be maximized and nontarget
effects can be minimized. 相似文献
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钻屑、钻井液固化处理及对环境的影响分析 总被引:10,自引:3,他引:10
钻屑和废钻井液的固化处理是现阶段钻井废物无害化处理的主要研究方向,研究利用固化剂对钻屑和废泥浆进行固化处理,优选配方(水泥+粉煤灰+添加剂)进行固化处理;同时考查了钻屑、钻井液固化填埋后对周围环境的影响。结果表明,固化物浸出液的分析结果符合国家危险废物鉴别标准(GB5085.3-1996)和国家污水综合排放标准(GB8978-1996),对周围环境水质调查监测,环境水质未受到污染,与填埋前的监测指标变化不大。 相似文献
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This study used the stable 15N isotope to quantitatively examine the effects of cutting on vegetative buffer uptake of NO3(-)-N based on the theory that regular cutting would increase N demand and sequestration by encouraging new plant growth. During the summer of 2002, 10 buffer plots were established within a flood-irrigated pasture. In 2003, 15N-labeled KNO3 was applied to the pasture area at a rate of 5 kg N ha(-1) and 99.7 atom % 15N. One-half of the buffer plots were trimmed monthly. In the buffers, the cutting effect was not significant in the first few weeks following 15N application, with both the cut and uncut buffers sequestering 15N. Over the irrigation season, however, cut buffers sequestered 2.3 times the 15N of uncut buffers, corresponding to an increase in aboveground biomass following cutting. Cutting and removing vegetation allowed the standing biomass to take advantage of soil 15N as it was released by microbial mineralization. In contrast, the uncut buffers showed very little change in 15N sequestration or biomass, suggesting senescence and a corresponding decrease in N demand. Overall, cutting significantly improved 15N attenuation from both surface and subsurface water. However, the effect was temporally related, and only became significant 21 to 42 d after 15N application. The dominant influence on runoff water quality from irrigated pasture remains irrigation rate, as reducing the rate by 75% relative to the typical rate resulted in a 50% decrease in total runoff losses and a sevenfold decrease in 15N concentration. 相似文献
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Richard Reader 《Environmental management》1988,12(6):803-808
To help determine whether plants should be grouped into guilds for environmental impact assessment, the responses of six members of a guild of deciduous forest herbs to selective tree harvesting were compared. Harvesting operations themselves (tree cutting and skidding) had little effect on five of the six species but the sixth species decreased more in cut plots than in uncut plots. Subsequent microclimatic changes, resulting from tree cutting, also affected guild members differently. In the first year after cutting, two species increased more in cut plots than in uncut plots, while three other species did not change in frequency of occurrence and the sixth species decreased more in cut plots than in uncut plots. This inconsistent response of guild members to tree harvesting suggests that caution should be exercised in using guilds to assess plant response to environmental change. 相似文献
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Environmental management of the stone cutting industry 总被引:1,自引:0,他引:1
Environmental Management of the stone cutting industry in Hebron is required to reduce the industry's adverse impact on the downstream agricultural land and the adverse impact on the drinking water aquifers. This situation requires the implementation of an industrial wastewater management strategic approach and technology, within the available technical and financial resources. Ten pilot projects at different locations were built at Hebron to reduce or eliminate the incompatible discharge of the liquid and solid waste to the environment and improve the stone cutting industry's effluent quality. A review of existing practices and jar test experiments were used to optimize the water recycling and treatment facilities. The factors reviewed included influent pumping rates and cycles, selection of the optimal coagulant type and addition methods, control of the sludge recycling process, control over flow rates, control locations of influent and effluent, and sludge depth. Based on the optimized doses and Turbidity results, it was determined that the use of Fokland polymer with an optimal dose of 1.5mg/L could achieve the target turbidity levels. The completion of the pilot projects resulted in the elimination of stone cutting waste discharges and an improvement in the recycled effluent quality of 44-99%. This in turn reduced the long term operating costs for each participating firm. A full-scale project that includes all the stone cutting firms in Hebron industrial area is required. 相似文献