蒲绒-芦苇机械混合复合材料的吸油性能

2010年本实验室开始生物质对柴油的吸附实验,和前人的结论一致,生物质热改性后其吸油和漂浮性能提高,但成本增加很多。受到前人复合吸油材料的启发,2012年开展了蒲绒-芦苇机械混合复合材料吸油和漂浮性能的研究,并采用正交实验对影响除油效果的因素进行优化。结果表明,蒲绒-芦苇复合材料较之芦苇吸油性能提高,且比各组分的叠加饱和吸油量还高。震荡使芦苇的漂浮率明显降低,但对蒲绒及复合材料的影响较小。正交实验结果显示,投加量0.7g,油膜厚度0.55 mm,不震荡时,蒲绒除油最佳;在相同条件下,粒径为380~500μm的芦苇除油最佳,蒲绒和该粒径的芦苇按质量比为1∶4混合成的复合材料的除油效果最佳。     

Lactic acid production with undefined mixed culture fermentation of potato peel waste

Potato peel waste (PPW) as zero value byproduct generated from food processing plant contains a large quantity of starch, non-starch polysaccharide, lignin, protein, and lipid. PPW as one promising carbon source can be managed and utilized to value added bioproducts through a simple fermentation process using undefined mixed cultures inoculated from wastewater treatment plant sludge. A series of non-pH controlled batch fermentations under different conditions such as pretreatment process, enzymatic hydrolysis, temperature, and solids loading were studied. Lactic acid (LA) was the major product, followed by acetic acid (AA) and ethanol under fermentation conditions without the presence of added hydrolytic enzymes. The maximum yields of LA, AA, and ethanol were respectively, 0.22 g g^?1, 0.06 g g^?1, and 0.05 g g^?1. The highest LA concentration of 14.7 g L^?1 was obtained from a bioreactor with initial solids loading of 60 g L^?1 at 35 °C.     

Benefits to poorly studied taxa of conservation of bird and mammal diversity on islands

Protected area delineation and conservation action are urgently needed on marine islands, but the potential biodiversity benefits of these activities can be difficult to assess due to lack of species diversity information for lesser known taxa. We used linear mixed effects modeling and simple spatial analyses to investigate whether conservation activities based on the diversity of well‐known insular taxa (birds and mammals) are likely to also capture the diversity of lesser known taxa (reptiles, amphibians, vascular land plants, ants, land snails, butterflies, and tenebrionid beetles). We assembled total, threatened, and endemic diversity data for both well‐known and lesser known taxa and combined these with physical island biogeography characteristics for 1190 islands from 109 archipelagos. Among physical island biogeography factors, island area was the best indicator of diversity of both well‐known and little‐known taxa. Among taxonomic factors, total mammal species richness was the best indicator of total diversity of lesser known taxa, and the combination of threatened mammal and threatened bird diversity was the best indicator of lesser known endemic richness. The results of other intertaxon diversity comparisons were highly variable, however. Based on our results, we suggest that protecting islands above a certain minimum threshold area may be the most efficient use of conservation resources. For example, using our island database, if the threshold were set at 10 km² and the smallest 10% of islands greater than this threshold were protected, 119 islands would be protected. The islands would range in size from 10 to 29 km² and would include 268 lesser known species endemic to a single island, along with 11 bird and mammal species endemic to a single island. Our results suggest that for islands of equivalent size, prioritization based on total or threatened bird and mammal diversity may also capture opportunities to protect lesser known species endemic to islands. Beneficios de los Taxa Poco Estudiados para la Conservación de la Diversidad de Aves y Mamíferos en Islas     

Mass,energy and material balances of SRF production process. Part 1: SRF produced from commercial and industrial waste

This paper presents the mass, energy and material balances of a solid recovered fuel (SRF) production process. The SRF is produced from commercial and industrial waste (C&IW) through mechanical treatment (MT). In this work various streams of material produced in SRF production process are analyzed for their proximate and ultimate analysis. Based on this analysis and composition of process streams their mass, energy and material balances are established for SRF production process. Here mass balance describes the overall mass flow of input waste material in the various output streams, whereas material balance describes the mass flow of components of input waste stream (such as paper and cardboard, wood, plastic (soft), plastic (hard), textile and rubber) in the various output streams of SRF production process. A commercial scale experimental campaign was conducted on an MT waste sorting plant to produce SRF from C&IW. All the process streams (input and output) produced in this MT plant were sampled and treated according to the CEN standard methods for SRF: EN 15442, EN 15443. The results from the mass balance of SRF production process showed that of the total input C&IW material to MT waste sorting plant, 62% was recovered in the form of SRF, 4% as ferrous metal, 1% as non-ferrous metal and 21% was sorted out as reject material, 11.6% as fine fraction, and 0.4% as heavy fraction. The energy flow balance in various process streams of this SRF production process showed that of the total input energy content of C&IW to MT plant, 75% energy was recovered in the form of SRF, 20% belonged to the reject material stream and rest 5% belonged with the streams of fine fraction and heavy fraction. In the material balances, mass fractions of plastic (soft), plastic (hard), paper and cardboard and wood recovered in the SRF stream were 88%, 70%, 72% and 60% respectively of their input masses to MT plant. A high mass fraction of plastic (PVC), rubber material and non-combustibles (such as stone/rock and glass particles), was found in the reject material stream.     

锯末+乙醇作为混合碳源去除地下水中硝酸盐的影响因素研究

本试验采用室内试验装置,研究了 pH、温度、硝酸盐浓度对锯末+乙醇作为混合碳源去除地下水中硝酸盐的影响结果表明,pH值在5～10内变化时对锯末+乙醇混合碳源体系的硝酸盐去除率影响较大,pH ＞7时的硝酸盐去除率明显高于pH ＜7时的去除率;并且随着pH值的增加,亚硝酸盐的积累量越多,锯末+乙醇混合碳源体系最佳的pH值范围是7～8.锯末+乙醇混合碳源体系受温度的影响较大,温度为8.5、15℃时的反硝化速率显著低于25℃时的速率,25℃时的反硝化速率分别是8.5、15℃时的3倍和1.5倍,锯末+乙醇混合碳源体系适宜的温度范围为25 ～35℃进水硝酸盐浓度也会影响锯末+乙醇混合碳源体系的反硝化效果,硝酸盐氮浓度在67.8 ～113 mg·L-1范围内变化时,反应体系的硝酸盐去除效果较好反应初期,硝酸盐浓度越大混合碳源体系的反硝化速率就越低,可能较大的硝酸盐负荷对反硝化细菌产生毒害作用而不利于硝酸盐的去除.     

乳化油在汽车发动机上的应用及探讨

本文对乳化油的乳化性能和在汽车发动机上的发展现状进行了探讨,分析对比了混合燃料的优缺点。研究表明：汽车发动机燃用乳化油可提高热效率,有效降低NOx及碳烟排放,但动力性略差,CO排放有所增加。最后阐述了我国乳化油未来发展优势。     

Machining efficiency of powder mixed near dry electrical discharge machining based on different material combinations of tool electrode and workpiece electrode

Powder mixed near dry electrical discharge machining (PMND-EDM) is a novel electrical discharge machining (EDM) process. It is proposed to further improve the machining efficiency of dry EDM. The principle of material removal in PMND-EDM is illustrated and its deionization principle is proposed. The influence of residual heat on MRR is analyzed. The concept of superfluous residual heat is proposed. The material removal rate (MRR), the main index of machining efficiency for PMND-EDM process, is researched. Single factor experiments are performed to get effect of peak current, pulse on time, pulse off time, flow rate, tool rotational speed, air pressure and powder concentration on MRR under different material combinations of tool electrode and workpiece electrode. Thermal phenomena in PMND-EDM are illustrated. Effect of each process parameter on MRR of PMND-EDM is gotten and analyzed based on the deionization principle of PMND-EDM. Differences in MRR under different material combinations are found out. Brass tool electrode and W18Cr4V workpiece gain higher MRR under most of discharge conditions, while the superiority of copper tool electrode and 45 carbon steel workpiece in MRR arise when there is improper heat dissipation. The difference is analyzed based on the deionization principle of PMND-EDM.     

混酸消解玻璃纤维滤筒滤膜法测定大气颗粒物中的铅

用高氯酸、硝酸和氢氟酸组成的混酸在加热的条件下消解玻璃纤维滤筒滤膜采集的铅尘样品,可基本除去滤膜中的硅。大部分除去滤筒中的硅,残留的硅酸对铅的溶出和准确测定不干扰。因此是取代索氏提取法和酸煮法的理想方法。     

航空发动机燃油系统附件低温试验方法

目的 探索一种航空发动机燃油系统附件低温试验方法.方法 梳理对比国内外航空发动机燃油系统附件低温试验方法的差异,分析国内外标准规定的试验温度差异的来源,检测3号喷气燃料的实际低温特性,验证?51℃的试验温度对3号喷气燃料的不适用性.分析航空发动机系统附件低温工作时会升温的特点,提出尽量模拟起动过程的低温试验方法.结果 利用提出的试验方法,在环境温度为?55℃、燃油温度为?40℃下,进行了135 h低温试验,额外单独进行1000次模拟发动机低温起动过程.试验过程中,某型主燃油泵调节器工作正常,并随某航空发动机通过了某飞机在我国北方某机场的高寒试飞试验.结论 GJB 241A规定的燃油温度?51℃或黏度12 mm2/s对应的温度(?56℃)不适用于3号喷气燃料,环境温度为?55℃,燃油温度为?40℃,并尽量模拟发动机低温起动过程的低温试验方法能够有效验证航空发动机燃油系统附件的低温工作能力.     

1961~2019年黄河流域大气自净能力指数变化特征分析

利用2015~2019年环境空气质量监测数据和黄河流域73个站点1961~2019年的气象观测资料,对11个站点的大气自净能力指数的适用性及其与环境空气质量之间的关联性进行了验证,并分析了黄河流域大气自净能力指数的时空变化特征及影响因子.结果表明,1961~2019年黄河流域大气自净能力指数整体呈下降趋势,下降速率为每10a下降0.18t/（d×km²）,平均值为4.44t/（d×km²）,且在1969年达到最大值,为5.32t/（d×km²）,2011年达到最小值,为3.81t/（d×km²）;黄河流域73个站点中有64个站点大气自净能力指数呈下降趋势,50个站点呈显著和极显著下降趋势.从年内变化看出,黄河流域大气自净能力指数最高值出现在4月,为5.30t/（d×km²）,最低值出现在1月,为3.48t/（d×km²）.在年空间分布上,黄河流域大气自净能力指数分布以青海西南部,山东、四川大部分地区,内蒙古、宁夏以及甘肃少部分地区,陕西西安,山西的五寨和右玉等大气自净能力较好,大气自净能力指数在4.69~7.18t/（d×km²）,其余地区大气自净能力相对较差.影响因子中,混合层高度与大气自净能力指数呈极显著正相关,相关系数为0.63（n=4307）;小风日数与大气自净能力指数呈极显著负相关,相关系数为-0.78（n=4307）,日平均风速³2.5m/s的日数及日平均风速³5.5m/s的日数与大气自净能力指数均呈极显著正相关,相关系数分别为0.78和0.55（n=4307）;降水日数与大气自净能力指数呈极显著正相关,相关系数为0.18（n=4307）,中雨及以上日数与大气自净能力指数呈显著正相关,相关系数为0.03（n=4307）,黄河流域小雨对大气自净能力的影响明显高于中雨.逐步回归分析显示,大气自净能力指数主要受日平均风速³2.5m/s的日数、降水日数和混合层高度的综合影响,其中,日平均风速³2.5m/s的日数对大气自净能力指数的贡献率最大,其贡献为正.