单片机控制磁粉制动器模拟加载系统的研究(第Ⅰ报) 磁粉制动器性能试验及控制系统设计与分析

进行了磁粉制动器动态性能研究,求出了传递函数和制动扭矩过渡过程的响应函数。设计了单片机控制系统,对单片机作为比例调节器进行了改进,求出了控制系统的传递函数和响应函数。通过改进控制系统和完善反馈程序,从外部改善了磁粉制动器的使用性能,提高了系统的加载精度和响应速度。     

我国土壤质量及其评价研究的进展

在阐述了土壤质量的内涵基础上,分析了土壤质量和土壤健康、土地质量及土壤服务功能的联系。重点对我国土壤质量的评价研究进行了回顾和概述,从指标体系的选取和评价方法入手,探讨了评价的发展过程,分析了我国土壤评价指标体系因子选择的范围,在论述了国际土壤质量最新进展的基础上,指出了生物学指标研究是需要加强的方向;同时着重分析了我国土壤质量评价方法研究的进展,对我国土壤质量评价的方法进行了概括,指出了空间化,过程化,应用化和综合化的发展方向,并讨论了我国土壤评价研究的方向和趋势。     

浅谈生态旅游

本文阐述了生态旅游产生的背景，含义；介绍了我国的生态旅游资源状况；探讨了目前生态旅游发展中存在的问题；提出了相应的对策。     

水利水保工程在社会主义新农村建设中的作用

对遂宁市社会主义新农村建设示范村鸡头寺村水利水保工程发挥作用的调研结果表明:水利水保工程在社会主义新农村建设中彰显了巨大的作用,它为抗旱减灾夺丰收提供了基本的保障,夯实了农村发展基础,增强了农业发展后劲,促进了现代农业、特色产业的发展,为调整农村产业结构、助农增收搭建起了平台,改善了生态环境和群众的生活条件,促进了村风文明。分析了水利水保发展不足给新农村建设带来的严重影响,提出了具体的对策。     

水土保持综合治理在现代农业发展中的作用──以南康市茶叶坳小流域和赣县枧田小流域为例

南康市茶叶坳小流域和赣县枧田小流域水土保持综合治理为当地现代农业发展提供了生态保障、夯实了发展基础、培育了产业基地、催生了机制创新、造就了新型农民,取得了明显的生态、经济和社会效益,不仅改善了当地的生态环境,而且显现出现代农业的雏形,为现代农业发展做出了应有的贡献。提出了新形势下水土保持综合治理在更高层次上助推现代农业发展的对策。     

解读新《中华人民共和国水土保持法》的法条体系

新《中华人民共和国水土保持法》于2010年12月25日通过全国人大常委会的修订,其法条体系和突出特点可归纳为10个强化。包括强化了政府的水土保持目标责任,强化了水土保持规划的法律地位,强化了水土流失预防,强化了生产建设项目水土保持方案管理,强化了水土流失治理,强化了水土保持投入机制,强化了水土保持监测,强化了水土保持监督管理,强化了违法行为的处罚,强化了责任追究与代履行。     

东北地区旱地农业研究进展与发展对策

系统总结了40多年来东北地区旱地农业研究取得的进展,分析了当前东北地区旱地农业面临的问题,揭示了影响东北地区旱地农业生产的气候变化、水分供需、农田侵蚀和面源污染规律,重新制定了东北地区耕作制度区划,突破了一系列旱地农业生产关键技术,形成了多套适合东北不同区域的旱地农业综合技术模式,明确提出了现阶段东北旱地农业所面临的挑战,并指出了未来东北旱地农业的发展对策。     

产学研结合 促进农业产业化发展

华南农业大学以技术入股的方式,与广东省温氏食品集团有限公司合作,实现了产学研相结合,促进了农业产业化的发展,由于有了高校的科技优势作依托,企业发展有了强大后盾,实现了决策科学化,管理科学化和生产科学化。与企业合作,学校走出了一条产学研相结合的新路,丰富了教学内容,开辟了科研新天地,建立了稳定的教学实践基地,巩固了学生的专业思想,改善了办学条件,提高了办学活力,实践证明这是一条成功的办学之路。     

兴国县实施国家水保重点工程的成效分析

在野外调查的基础上,结合历史资料重点分析了兴国县实施国家水保重点工程的成效。1983—2005年,兴国县水土流失面积减少了60%,山地植被覆盖度上升了43.4%,年泥沙流失量减少了67.6%,河床普遍降低0.4 m,有林地面积净增5.4倍,土地产出率增长54.2%,农民年人均纯收入增加了17倍,贫困人口减少了12.9万人,水土流失恶化的趋势得到了有效遏制,生态环境得到了改善,昔日的穷乡僻壤,如今变成了绿树掩映的小康县。总结了管理上的成功经验与技术上的五大治理模式。在分析了治理成本后认为,国家的水保重点工程是极具前瞻性的,其出发点是正确的,是从根本上解决老百姓的贫困问题,与现在的新农村建设政策相一致。     

单片机控制磁粉制动器模拟加载系统的研究(第Ⅰ报)——磁粉制动器性能试验及控制系统设计与分析

进行了磁粉制动器动态性能研究,求出了传递函数和制动扭矩过渡过程的响应函数。设计了单片机控制系统,对单片机作为比例调节器进行了改进,求出了控制系统的传递函数和响应函数。通过改进控制系统和完善反馈程序,从外部改善了磁粉制动器的使用性能,提高了系统的加载精度和响应速度。     

Utilization Potential of Peats – a Study on Peat Biodegradability Determined by Respirometric Method

The biodegradation of different peat types was studied with a manometric respirometric test. Compaction peat and sphagnum peat samples were analysed, and the effect of peat pH on biodegradation behaviour was evaluated. Only minor (BOD/ThOD?<?0.4%) biodegradation was observed with compaction peat samples, and the stable state, in which biodegradation stopped, was achieved during a two month period. As expected, sphagnum peat samples with a lower decomposition rate degraded more than compaction peat samples. Alkalinity (pH between ca. 4–9) of the peat was noticed to reduce the degree of biodegradation and accelerate the achievement of the stable state.     

粪便好氧堆肥过程中温度对有机物的降解和氮的保持特性影响

研究堆肥过程温度对有机物的降解,尤其是氮的迁移转化的影响,对于提高堆肥效率和保持更多的氮在产物中具有重要意义。本研究采用密闭式好氧堆肥反应器,模拟高温(60℃)和中温(35℃)两种典型的堆肥温度,以新鲜锯末为空白载体,在含水率60%以及连续强制供气的条件下,进行了为期两周的试验,评估温度对于粪便中有机物的降解和氮的迁移转化的影响。结果表明,粪便中有机物(固体中的有机物,总有机碳、化学需氧量)高温去除率70%,比中温的63%高出11%;且堆肥腐熟期高温(6～8 d)比中温(10～11 d)缩短约4 d。总氮的损失高温(17%)比中温(31.4%)减少了约50%。高温下氮的损失发生在堆肥反应的第1 d,由无机氮的迅速减少造成,有机氮几乎未变。中温下氮的损失在堆肥反应的前4 d,由无机氮和有机氮共同参与。研究表明,温度对堆肥具有显著的影响,控制合适的堆肥温度不仅可以加快有机物的腐熟,提高效率,还可以减少氮的损失,提高产物的肥效。     

Non-additive effects of mixing different sources of dissolved organic matter on its biodegradation

To examine the potential impact of plant species richness on ecosystems, we studied non-additive effects of different plant litters on the biodegradation rate of dissolved organic matter (DOM) when mixing plant leaf-derived DOM derived from different plant species. A full factorial biodegradation experiment (31 possible singular and multiple combinations of five litter type-derived DOM sources) was conducted using plant litters from the five most abundant plant species in a subtropical watershed ecosystem, from which dissolved organic carbon (DOC) disappearance was measured. Loss of DOC over time was considered biodegradable DOC. We tested whether DOM diversity, measured as source species richness and composition, would affect biodegradation rates. Overall, we found significant non-additive (synergistic) effects of DOM diversity on biodegradation rates of DOM, which were explained both by plant species richness and composition. Across all treatments, a significantly higher biodegradation rate was correlated with the presence of DOM from higher nitrogen (N) containing plant litters; conversely, the presence of lower N decreased these rates. The N content and chemical characteristic of DOM might influence the magnitude of the synergistic effect. Our results suggest that loss of plant litter species diversity would not affect DOC biodegradation rate, provided that at least two species are conserved. However, the variability in DOC biodegradation rate across the treatments decreased with increased DOM diversity at three incubation time points. Our results also indicate that in an ecosystem with low plant biodiversity, loss of key species such as Lophostemon confertus could reduce the synergistic effects on DOC biodegradation rate.     

Chemical Composition of Cloud Water in the Puerto Rican Tropical Trade Wind Cumuli

In this biological oxygen demand (BOD) study, the manometric respirometric BOD OxiTop® method was used to monitor the biodegradation of two summer grade (SFO 1 and 2) and two winter grade light fuel oils (WFO 1 and 2) in OECD 301 F conditions, in groundwater, and in two different Finnish forest soils (mineral-poor and mineral-rich). The biodegradation measurements in the OECD 301 F conditions were carried out in two nutrient solutions for 28 days. In both solutions WFO 1 reached the highest biodegradation degree, 32% in the solution OECD 301 F, and 70% in a solution containing additional ammonium chloride. In groundwater conditions all the biodegradation degrees of fuel oils remained below 2% within the 28-day period. SFO 1 reached the highest 30 day biodegradability (4%) in mineral-poor soil, 18% in mineral-rich soil. In a 189-day measurement in a mineral-rich soil, the biodegradation degree for the SFO 1 was 94%. The manometric respirometric method proved to be a very suitable and practicable measurement method for the purpose of biodegradation studies of highly volatile light fuel oils, because in this method samples are treated to a lesser degree than in conventional methods, and dilutions are not needed. Results also indicated a considerable effect of conditions on the biodegradability in both water and soil environments. The results of these biodegradation studies could be used when planning in situ treatment methods based on natural biodegradation. In situ treatment methods are eco-efficient, and are especially suitable for sparsely populated sites.     

水体中硝基苯厌氧降解微生物的筛选及其降解特性研究

以硝基苯为碳源,采用间歇式曝气方式,经90d驯化培养,从处理硝基苯废水的生物活性污泥中分离得到13株高效降解菌,在厌氧环境条件分离纯化,筛选得到降解能力最强的MY4菌,并研究了其对不同浓度硝基苯的降解特性。结果表明,经16SrRNA鉴定,MY4菌属于兼性葡萄球菌属（Staphylococcus sp）,其在104～107CFU·mL^-1范围内对硝基苯的去除率没有显著差异,降解率均为65%,硝基苯的降解速率在3～5d期间达到最大。高浓度的硝基苯对微生物的降解过程存在抑制作用,随着浓度的增高,其降解半衰期明显延长。GC-MS分析表明,硝基苯经MY4菌株降解后的主要产物为苯胺。     

The use of biodegradation signatures and biomarkers to differentiate spills of petroleum hydrocarbon liquids in the subsurface and estimate natural mass loss

The history of diesel fuel spills into a sand aquifer was investigated using biodegradation signatures and biomarker compounds of the light non-aqueous phase liquid (LNAPL) petroleum hydrocarbons. Samples of the weathered LNAPL diesel from 28 monitoring wells, along with LNAPL from cores, in a 2 ha plume were characterised by GC–MS techniques. The relative extent of biodegradation was assessed using ratios of partially degraded and resistant compounds including n-alkanes (n-C17), pristane and phytane. Biomarkers cadalene and methyldibenzothiophenes were also used to differentiate two different crude oil sources (Middle Eastern and South-east Asian). Age relationships were also investigated from the LNAPL composition. Both the extent and distribution of biodegradation and biomarkers identified a recent spill into the aquifer and traced its spread within the existing LNAPL plume. Evidence of an older, discrete and more degraded spill was also identified within the larger plume. Importantly, these analyses also identified a loss of as much as 80% of spilled diesel mass through biodegradation and other natural attenuation processes. Oxidised hydrocarbon material immediately above the LNAPL in the profile and reduced pristane:phytane ratios at the top of the LNAPL profile, provide supporting evidence of aerobic biodegradation.     

Isotopic evidence and quantification assessment of in situ RDX biodegradation in the deep unsaturated zone

Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is an explosive compound whose extensive use has resulted in significant contamination of soils and groundwater worldwide. We studied its in situ biodegradation along the unsaturated zone beneath an explosives wastewater lagoon using compound-specific isotope analysis (CSIA) of RDX in the unsaturated zone, together with biodegradation slurry experiments under anaerobic conditions. We found the highest degradation potential of RDX and its nitroso derivatives in the upper part of the soil profile while in the lower parts, RDX-degradation potential was lower and the nitroso derivatives tended to persist. This was also observed in the field, as reflected by the isotopic composition of RDX along the profile. We also found a correlation between biodegradation potential and clay content: biodegradation was further enhanced in layers characterized by high-clay content or in those influenced by the high-clay layers. In addition, in the presence of high organic matter content, further enhancement of biodegradation was observed. We obtained different isotopic enrichment factors (?) for RDX biodegradation in different sections of the unsaturated profile and suggest that different degradation pathways exist simultaneously in situ, in variable proportions. Using the range of enrichment factors, we were able to assess the biodegradation extent of RDX at different sampling points along the profile, which ranged between 30 and 99.4%. The novel application of CSIA together with slurry experiments provides better insight into degradation processes that are otherwise difficult to detect and assess.     

Uptake of Hydrocarbon by Pseudomonas fluorescens (P1) and Pseudomonas putida (K1) Strains in the Presence of Surfactants: A Cell Surface Modification

The objective of this research was the evaluation of the effects of exogenous added surfactants on hydrocarbon biodegradation and on cell surface properties. Crude oil hydrocarbons are often difficult to remove from the environment because of their insolubility in water. The addition of surfactants enhances the removal of hydrocarbons by raising the solubility of these compounds. These surfactants cause them to become more vulnerable to degradation, thereby facilitating transportation across the cell membrane. The obtained results showed that the microorganism consortia of bacteria are useful biological agents within environmental bioremediation. The most effective amongst all, as regards biodegradation, were the consortia of Pseudomonas spp. and Bacillus spp. strains. The results indicated that the natural surfactants (rhamnolipides and saponins) are more effective surfactants in hydrocarbon biodegradation as compared to Triton X-100. The addition of natural surfactants enhanced the removal of hydrocarbon and diesel oil from the environment. Very promising was the use of saponins as a surfactant in hydrocarbon biodegradation. This surfactant significantly increases the organic compound biodegradation. In the case of those surfactants that could be easily adsorbed on cells of strains (e.g., rhamnolipides), a change of hydrophobicity to ca. 30-40% was noted. As the final result, an increase in hydrocarbon biodegradation was observed.     

印度热带森林干旱扰动土壤的微生物碳, 氮, 磷的研究

Variations in microbial biomass C (MB-C),N (MB-N) and P (MB-P) along a gradient of different dominant vegeta- tion covers (natural forest,mixed deciduous forest,disturbed savanna and grassland ecosystems) in dry tropical soils of Vindhyan Plateau,India were studied from January 2005 to December 2005.The water holding capacity,organic C,total N,total P and soil moisture content were comparatively higher in forest soils than in the savanna and grassland sites.Across different study sites the mean annual MB-C,MB-N and MB-P at 0-15 cm soil depth varied from 312.05 ± 4.22 to 653.40 ± 3.17,32.16 ± 6.25 to 75.66 ± 7.21 and 18.94 ± 2.94 to 30.83 ± 23.08 μg g ?1 dry soil,respectively.At all the investigated sites,the maximum MB-C,MB-N and MB-P occurred during the dry period (summer season) and the minimum in wet period (rainy season).In the present study,soil MB-C,MB-N and MB-P were higher at the forest sites compared to savanna and grassland sites.The differences in MB-C,MB-N and MB-P were significant (P 0.001) among sites and seasons.The MB-C (P 0.0001),MB-N (P 0.001) and MB-P (P 0.0001) were positively correlated with organic C,while the relationship between soil moisture and MB-C,MB-N and MB-P (P 0.001,P 0.01 and P 0.0001,respectively) was negative.The decreasing order of MB-C,MB-N and MB-P along study ecosystems was natural forest mixed deciduous forest savanna grassland.The results suggested that deforestation and land use practices (conversion of forest into savanna and grassland) caused the alterations in soil properties,which as a consequence,led to reduction in soil nutrients and MB-C,MB-N and MB-P in the soil of disturbed sites (grassland and savanna) compared to undisturbed forest ecosystems.     

生物表面活性剂及Tween-80在一株菲降解菌降解过程中的作用研究

Numerous studies have been devoted to the physical-chemical weathering processes leading to the creation of unique soil formations having their own history that induce soil-biotic diversity. However, the extent to which unique geomorphic formations influence soil biotic seasonal variation is not clear. Our aim was to define seasonal variations of soil biota in soils of different-aged terraces of the Makhtesh Ramon anticline erosional cirque in southern Israel. The strong effect of Makhtesh Ramon (Ramon Crater) erosional fluvial terrace age initiated by climatic changes during the Late Pleistocene–Early Holocene period on seasonal variations in both soil properties and the abundance and composition of soil biota were demonstrated. However, age dependence was not constant and values for observed soil properties and microbial activity were negligible between younger and older terraces for certain seasons, while free-living nematodes along with bacteria-feeding group were strongly dependent on the geomorphic features of the ages throughout the study period.