移动式双螺杆空气压缩机系统动态特性分析

在对移动式双螺杆空气压缩机系统组成及运行原理分析基础上,建立柴油发动机子系统、空气压缩机主机子系统和进气控制子系统数学模型,利用Matlab/Simulink平台构建空气压缩机系统仿真模型,对空气压缩机在加/卸载运行条件下的系统压力、流量和轴功率进行仿真分析,以研究双螺杆空气压缩机动态特性;并通过试验验证数学模型的有效性。仿真和试验结果表明:用气量对空气压缩机系统动态特性产生影响,用气量波动越大,空气压缩机系统轴功率越高,能量利用率越低,且压力波动越大;用气量越大,空气压缩机加卸载频率越低,系统能量利用率越高;仿真结果和试验结果最大相对误差小于5%,所建立的数学模型能反映空气压缩机动态加、卸载运行过程。该研究可为空气压缩机系统节能运行提供参考。     

Remediation of PAH-contaminated soil by pulsed corona discharge plasma

Purpose

Polycyclic aromatic hydrocarbons (PAHs) are hydrophobic organic pollutants of great environmental and health concern. PAHs are very persisted in soils and sediments which make it very difficult to remove them from soil. Therefore, remediation of PAH-contaminated sites has become an important environmental issue. The objective of this work was to study PAH degradation by pulsed corona discharge plasma system.

Materials and methods

Phenanthrene (Phe) was used as the model pollutant. The Phe-contaminated soil samples were prepared by adding appropriate amount of Phe dichlormethane solution (200 mg/L) into a given amount of pretreated soil, and Phe distributed uniformly in the soil at about 100 mg/kg. The experimental system mainly consisted of a pulse high-voltage power supply and a reactor vessel. The high-voltage electrode comprised of six stainless-steel needles and the ground electrode was a stainless-steel plate. The concentration of Phe was determined by HPLC system after being extracted out from soil. Effect of run parameters such as pulse voltage, pulse frequency, air flow rate, gas atmosphere, and initial concentration of Phe on Phe degradation was investigated, and the consumption of ozone during discharge process was also studied.

Results and discussion

The results showed that degradation efficiency of Phe (initial concentration 100 mg/kg) approached approximately 70 % after 40 min of discharge treatment under the conditions of pulse voltage 18 kV, pulse frequency 70 Hz, and air flow rate 0.8 L/min, which increased with the pulse voltage and pulse frequency due to the enhancement of input energy. An optimal air flow rate of 0.8 L/min was observed to obtain a maximum Phe degradation efficiency. Oxygen atmosphere favored Phe degradation due to high concentration of generated O-reagents, and ozone was found to act on Phe degradation. The concentration of Phe had influence on remediation capacity that increased with the amount of Phe in soil.

Conclusions

The results confirmed that pulsed corona-discharge plasma was a potential method for remediation of PAH-contaminated soil. This study offered a viable treatment option for remediation of Phe-contaminated soil, which was expected to remove PAHs other than Phe from soil with further development.

     

Taxon-specific responses of soil microbial communities to different soil priming effects induced by addition of plant residues and their biochars

Purpose

This work investigated changes in priming effects and the taxonomy of soil microbial communities after being amended with plant feedstock and its corresponding biochar.

Materials and methods

A soil incubation was conducted for 180 days to monitor the mineralization and evolution of soil-primed C after addition of maize and its biochar pyrolysed at 450 °C. Responses of individual microbial taxa were identified and compared using the next-generation sequencing method.

Results and discussion

Cumulative CO₂ showed similar trends but different magnitudes in soil supplied with feedstock and its biochar. Feedstock addition resulted in a positive priming effect of 1999 mg C kg^?1 soil (+253.7 %) while biochar gave negative primed C of ?872.1 mg C kg^?1 soil (?254.3 %). Linear relationships between mineralized material and mineralized soil C were detected. Most priming occurred in the first 15 days, indicating co-metabolism. Differences in priming may be explained by differences in properties of plant material, especially the water-extractable organic C. Predominant phyla were affiliated to Acidobacteria, Actinobacteria, Chloroflexi, Gemmatimonadetes, Firmicutes, Planctomycetes, Proteobacteria, Verrucomicrobia, Ascomycota, Basidiomycota, Blastocladiomycota, Chytridiomycota, Zygomycota, Euryarchaeota, and Thaumarchaeota during decomposition. Cluster analysis resulted in separate phylogenetic grouping of feedstock and biochar. Bacteria (Acidobacteria, Firmicutes, Gemmatimonadetes, Planctomycetes), fungi (Ascomycota), and archaea (Euryarchaeota) were closely correlated to primed soil C (R ²?=??0.98, ?0.99, 0.84, 0.81, 0.91, and 0.91, respectively).

Conclusions

Quality of plant materials (especially labile C) shifted microbial community (specific microbial taxa) responses, resulting in a distinctive priming intensity, giving a better understanding of the functional role of soil microbial community as an important driver of priming effect.

     

Genetic diversity of Quercus glandulifera var. brevipetiolata populations in three forest communities with different succession stages

In order to understand the relationship between population succession and its genetic behavior, random amplified polymorphic DNA (RAPD) technique was used to analyze the genetic diversity of Quercu glandulifera var. brevipetiolata populations in three forest communities with different succession stages (coniferous forest, coniferous and broad-leaved mixed forest, evergreen broad-leaved forest). The results showed that 145 repetitive loci were produced in 60 individuals of Q. glandulifera using 11 primers, among which 120 loci were polymorphic, and the total percentage of polymorphic loci was 82.76% with an average of 64.14%. Estimated by the Shannon information index, the total genetic diversity of the three populations was 0.4747, with an average of 0.3642, while it was 0.3234, with an average of 0.2484, judged from the Nei index. Judged from percentage of polymorphic loci, Shannon inform at ion index and Nei index, the genetic diversity followed a decreasing order: coniferous forest > broad-leaved mixed forest > evergreen broad-leaved forest. Analysis of molecular variance (AMOVA) showed that 69.73% of the genetic variance existed within populations and 30.27% of the genetic variance existed among populations. The coefficient of gene differentiation (GST) was 0.2319 and the gene flow (N _m) was 1.6539. The mean of genetic identity among populations of Q. glandulifera was 0.8501 and the mean of genetic distance was 0.1626. The genetic identity between the Q. glandulifera population in the coniferous forest and that in the coniferous and broadleaved mixed forest was the highest. UPGMA cluster analysis based on Nei’s genetic distance showed that the population in the coniferous forest gathered with that in the coniferous and broad-leaved mixed forest firstly, then with that in the evergreen broad-leaved forest. The genetic structure of Q. glandulifera was not only characteristic of the biological characteristics of this species, but was also influenced by the microenvironment in different communities. __________ Translated from Journal of Northwest Forestry University, 2008, 23(1): 18–22 [译自: 西北林学院学报]     

水稻透射光谱与氮含量的相关性研究

采用小区试验研究了水稻叶片氮含量与透射光谱的相关性。用“秀水110”建立诊断模型,再用“协优9308”进行检测,分析一阶导数光谱与叶片氮含量的相关性。结果表明,一阶导数光谱与氮含量显著相关,相关系数可达R2=0.74。预测模型可达R2=0.84。与一阶导数光谱相比,还建立了3个植被指数：蓝波段透射光谱氮指数(BETNI)、波段透射光谱氮指数(YETNI)和红波段透射光谱氮指数(RETNI),并分别计算了它们在这三个波段的特殊波长的值。在这些特殊波长处,3个指标与氮含量的相关性明显比单叶片的透射光谱的相关性显著。YETNI610,YETNI630,YETNI643,YETNI652,and RETNI能够很好的预测氮含量;对于“协优9308”的预测结果显示YETNI570,YETNI592和RETNI最优。分析结果显示,透射光谱的氮指标（YETNI570,YETCI592,and RETNI）能够最好地预测氮含量。     

湘两优糯粱一号品种特性与再生技术研究

湘两优糯粱一号是利用高粱温光互作核不育原理,用湘糯梁 S-1与湘10721品种杂交而成的世界上第一个两系法选配的高粱新品种。它的杂种优势,品种特性,秋茬再生能力与其他常规品种有何差异？尤其是常规品种在本地只种春季一茬,不存在秋季再生的情况下,如何根据浙江省的气候,科学确定春茬砍杆时间和秋季再生茬安全抽穗时间,以及相应的秋季配套技术,是作者本文的研究目的。经过作者5年的试验研究,在摸清了该组合生育期短、茎杆粗壮、株型紧凑、杂种优势显著、适应性广、产量高和再生能力极强等特性后,进而研究与掌握了春茬收获时间、低茬秋季再生技术     

浙江省农业气象灾害特点及防灾措施

农业气象灾害是造成农业生产不稳定的主要因素之一。根据浙江省历年气象资料和灾情资料,分析了浙江省台风、洪涝、干旱、低温冻害等主要农业气象灾害的发生频率和地域分布特点,分析了近几年浙江省农业气象灾害的变化特征,并提出了防灾措施,从而为防御农业气象灾害,减轻灾害损失,保障农业生产稳产、增产提供依据。     

不同水稻品种对铜镉的吸收与耐性研究

以七种水稻品种为材料,通过温室水培试验,研究七个水稻品种Cu,Cd吸收累积特征的差异。结果表明：汕优63相对其它六种水稻品种属于高积累水稻品种,对重金属Cu,Cd较敏感;武育粳3号属于相对低积累水稻品种,对重金属Cu,Cd相对不敏感。     

金华佛手早期落果生理原因初探

佛手幼果发育过程中，蛋白质含量随幼果发育略有提高，开花后第５～２５天由５．６４１ｍｇ／ｇ鲜重增至８．０７６ｍｇ／ｇ鲜重。吲哚乙酸含量在开花后第５～１０天由４３．３７μｇ／ｇ干重升至７４．４０μｇ／ｇ干重，然后急剧下降，至开花后第２５天降至１３．５０μｇ／ｇ干重。吲哚乙酸氧化酶活性显示，在开花后第１０～２５天由２．７２μｇ／ｈ·ｍｌ酶液升至１１．１７μｇ／ｈ·ｍｌ酶液。佛手幼果发育过程中，吲哚乙酸氧化酶活性升高，引起吲哚乙酸含量下降，蛋白质等养分积累减少，可能是佛手早期落果的生理原因之一。     

加强污染综合治理促进畜牧业可持续发展

我省是全国畜禽养殖业较为发达的省份。伴随着养殖业的发展,畜禽养殖业污染问题日益突出。养殖业污染来源广泛,成分复杂,主要由畜禽粪便、废气污水、有害气体、饲料中富余营养、药物及饲料添加剂和消毒剂残留等组成,如果得不到有效处理,则会对土壤、水体和空气构成严重污染。因