Effect of bulk density of coking coal on swelling pressure

Coking coals are the important raw materials for the iron and steel industries and play an important role on its sustainable development, especially on the stamp-charging coke making with the characteristics of increasing the bulk density. There is a significance on the reasonable usage of the coking coal resource with the reduced production cost, improved efficiency of the economy to develop the stamp-charging coke making technology. Important effects of the density of coking coal on the coking and caking properties were investigated. In the article, the maximum values of swelling pressure and variation of Laowan gas coal and Xinjian 1/3 coking coal, Longhu fat coal and Didao coking coal, which were mined at Shenyang and Qitaihe respectively, were investigated under different bulk densities during the coking. The results showed that when the values of density increased from 0.85 ton/m³ to 1.05 ton/m³, for the Laowan gas coal, swelling pressure variation and even the maximum value changed slightly. The swelling pressure was 3.63 KPa when the density was improved to 1.05 ton/m³; for the Xinjian 1/3 coking coal, the values of swelling pressure changed significantly and the maximum values was 82.88 KPa with the density improved to 1.05 when the coal was heated to 600℃. The coke porosity, which was investigated by automatic microphotometer, decreased from 47.4% to 33.1% with the increasing of the density from 0.85 ton/m³ to 1.05 ton/m³, and the decreased value was 14.3%. Meanwhile, the pore structures of four cokes were characterized by an optical microscope.     

Effect of bulk density of coking coal on swelling pressure

Coking coals are the important raw materials for the iron and steel industries and play an important role on its sustainable development, especially on the stamp-charging coke making with the characteristics of increasing the bulk density. There is a significance on the reasonable usage of the coking coal resource with the reduced production cost, improved efficiency of the economy to develop the stamp-charging coke making technology. Important effects of the density of coking coal on the coking and caking properties were investigated. In the article, the maximum values of swelling pressure and variation of Laowan gas coal and Xinjian 1/3 coking coal, Longhu fat coal and Didao coking coal, which were mined at Shenyang and Qitaihe respectively, were investigated under different bulk densities during the coking. The results showed that when the values of density increased from 0.85 ton/m³ to 1.05 ton/m³, for the Laowan gas coal, swelling pressure variation and even the maximum value changed slightly. The swelling pressure was 3.63 KPa when the density was improved to 1.05 ton/m³; for the Xinjian 1/3 coking coal, the values of swelling pressure changed significantly and the maximum values was 82.88 KPa with the density improved to 1.05 when the coal was heated to 600°C. The coke porosity, which was investigated by automatic microphotometer, decreased from 47.4% to 33.1% with the increasing of the density from 0.85 ton/m³ to 1.05 ton/m³, and the decreased value was 14.3%. Meanwhile, the pore structures of four cokes were characterized by an optical microscope.     

无线电干扰系统电磁辐射安全限值的研究

在严格遵循国家有关部门电磁辐射防护规定中的相关标准情况下,进行无线电干扰系统的实验和操作中,发现当系统长时间使用时,按照电磁辐射相关安全标准设置安全间距仍会对人体健康产生不利影响。文章根据实验数据,对电磁辐射相关安全标准进行了深入研究和探讨,在对国家安全标准探讨的基础上提出考虑电磁辐射危害时不能仅仅将人体作为点来考虑,应充分认识到人体作为等效天线的特征以及吸收功率的问题。     

中国矿产资源基地划定指标体系构建与应用——以铁矿为例

矿产资源基地是优化中国矿产资源勘查开发布局、保障国内资源有效供应的战略核心区域。在分析基地布局影响因素的基础上,从资源基础、开发条件、市场需求和国家战略等方面构建了矿产资源基地划定指标体系。其中资源基础包括预测资源量、查明资源储量和设计开采规模,开发条件包括缺水程度和交通优势度,市场需求包括后续冶炼加工企业布局与产值,国家战略主要体现为区域协调发展战略对矿产资源基地布局的要求。在此基础上,以铁矿为例开展了实证研究,采用聚类分析、核密度估计等方法对各单项指标进行了分析评价,在全国识别了辽宁鞍山—本溪等12个铁矿资源基地。研究结果可以为“十四五”时期中国矿产资源基地调整优化提供参考,对其他矿产资源空间政策区的划定具有一定借鉴意义。     

氯改性活性炭吸附单质铅(Pb0)的机理

利用量子化学中密度泛函方法系统研究氯改性活性炭吸附单质铅（Pb⁰）的机理,明确了氯改性对活性炭吸附Pb⁰的影响,计算得到吸附过程中各个吸附构型的吸附能、重要键长、对应的Mayor键级和铅的Mulliken原子电荷.几何优化选用B3LYP方法结合def2-SVP基组,单点能任务选用PWPB95双杂化泛函结合def2-TZVP基组进行计算.结果表明：对于扶手椅型（armchair）活性炭,氯改性将使活性炭对Pb⁰的吸附能降低74.034kJ/mol;对于锯齿型（zigzag）活性炭,氯改性基本不会改变活性炭对Pb⁰的吸附能力,因此氯改性总体上会减弱活性炭对Pb⁰的吸附作用,但是吸附类型依然为强烈的化学吸附.分别应用电子密度分布和Mayor键级进一步验证纯活性炭和氯改性活性炭对Pb⁰吸附类型,结果与吸附能分析一致.Mayor键级分析表明氯原子通过改变周围碳原子活性影响Pb⁰的吸附,而不是与Pb⁰直接作用.Mulliken原子电荷分析表明铅的原子电荷正相关于活性炭对其的吸附能,铅的原子电荷越大,对应的吸附构型的吸附能越高.此外笔者发现Pb⁰的引入对氯改性活性炭继续吸附Pb⁰有抑制作用.     

香溪河大型底栖动物24 h漂流规律研究

漂流行为是大型底栖动物适应河流水文过程的重要生物行为,也是研究河流底栖动物时空分布过程的重要依据,研究底栖动物的漂流规律对了解河流生态系统纵向格局的形成过程和演变机制具有重要意义.2017年8月选择湖北省香溪河的2条支流（九冲河与高岚河）研究大型底栖动物的漂流种类、昼夜节律和功能摄食类群构成.结果表明:①九冲河与高岚河漂流底栖动物均以蜉蝣目（Ephemeroptera）占绝对优势,相对丰度分别为76.9%、96.1%.九冲河的漂流物种数（35种）远高于高岚河（14种）.②优势物种分析表明,九冲河的优势物种为高翔蜉（Epeorus sp.）、弯握蜉（Drunella sp.）、四节蜉（Baetis sp.）、花翅蜉（Baetiella sp.）、扁蚴蜉（Ecdyonurus sp.）、沼石蛾（Limnophilidae sp.）、等翅石蛾（Philopotamidae sp.）和蚋（Simulium sp.）,高岚河的优势物种为花翅蜉和高翔蜉.③2条河流大型底栖动物的漂流均为显著的夜漂流类型,且漂流高峰期均出现在06:00.九冲河的夜漂者以襀翅目（Plecoptera）为主,高岚河以蜉蝣目为主.不同物种漂流的昼夜节律不同,高翔蜉、弯握蜉、扁蚴蜉、沼石蛾、等翅石蛾和蚋的第1个漂流密度高峰期均出现在20:00-22:00;四节蜉的第1个漂流密度高峰期出现在04:00-06:00;而花翅蜉的第1个漂流密度高峰期在九冲河出现的时间为04:00-06:00,在高岚河为02:00-04:00.④昼夜间漂流底栖动物的功能摄食类群和生活类型群落组成也有一定差异,但总体来看,漂流者的功能摄食类群均以收集者为主,以游泳生活者占主要优势.研究显示,九冲河与高岚河底栖动物的漂流节律表现出明显的差异性,其人为活动强度的差异是造成漂流规律差异的主要原因.      

蓝藻腐解对水中营养盐影响的模拟研究

为研究不同密度藻类腐解过程对水体营养盐再分配的影响,在太湖藻类聚集区采集沉积物柱状样进行室内加藻模拟实验,共设置B、C、D 3组加藻密度分别为2500、7500和15000 g·m-2的处理组,监测蓝藻腐解过程中上覆水体的溶解氧(DO)、氧化还原电位(Eh)、氨氮(NH_4~+-N)、总氮(TN)及总磷(TP)等理化指标的变化情况.结果表明,蓝藻腐解会使水体DO和Eh迅速下降,最终分别维持在0.1 mg·L~(-1)左右和-300~-400 mV之间,水体处于厌氧强还原状态;同时,厌氧强还原条件又加速了蓝藻死亡腐解过程,促进了藻体营养盐向上覆水的扩散,B、C、D组营养盐含量分别于实验第6、第10和第14 d达到峰值,TN平均增长速率分别为26.67、43.41和67.82 mg·L~(-1)·d~(-1),TP平均增长速率分别为3.30、5.53和8.35 mg·L~(-1)·d~(-1),NH_4~+-N浓度最大值分别为对照组的7、51、125倍,水体形成明显的氮磷污染负荷,且蓝藻衰亡导致的上覆水TN浓度升高持续时间较TP浓度升高持续时间要长.研究表明,蓝藻水华腐解过程中向上覆水体释放了大量的有机物和可溶性营养盐,降低了水体透明度,加剧了水体富营养化状况,诱发湖泛发生,也为蓝藻水华再次爆发提供了物质基础.     

北方高盐景观水体氮磷时空分布特征及富营养化评价

为掌握北方高盐景观水体的水环境状况,选取天津市中新生态城3个景观水体(清净湖、蓟运河和蓟运河故道)为研究对象,于2013年12月—2014年11月对其进行定期取样监测,开展水体氮磷污染特征分析及富营养化评价。结果表明:1)蓟运河、清净湖和蓟运河故道的TDS均值分别为3.42,4.64,20.2 g/L,属于高盐景观水体;2)水体TN和TP浓度逐月变化显著,水质整体上冬春季优于夏秋季,其中蓟运河TP和TN的浓度最大,且波动较大;3)根据TN/TP比值判定,研究区水体除清净湖在短时间表现为氮限制外,水体大部分时间段内表现为磷限制,P为主要限制因子;4)富营养化评价表明:水体均处于富营养状态,且有蓟运河>蓟运河故道>清净湖;5)相关性结果表明:TDS与电导率、水温及EI呈显著正相关,相关系数分别为0.905、0.822和0.645,盐度也是影响富营养化的关键因素。     

基于空间监视雷达散射回波的电离层电子密度探测方法

目的提高空间监视雷达的电离层电波环境适应性。方法 VHF-L波段大功率雷达信号经过电离层传播时会发生非相干散射,散射回波中包含电离层信息。结合雷达方程和电离层目标特征,基于电离层非相干散射原理,理论分析空间监视雷达用于电离层电子密度非相干散射探测的条件(包括雷达参数设置和波束扫描方式),给出电离层回波功率、自相关函数和电子密度表达式,利用Matlab编程对某大功率空间监视雷达原始数据处理得到电离层散射回波及电子密度。结果给出了空间监视雷达用于电离层电子密度非相干散射探测的基本条件,实测数据发现电离层回波和电子密度符合电离层变化特征。结论利用VHF-L波段大功率雷达空间散射回波探测电离层电子密度是可行的,为空间监视雷达电离层环境感知与传播自适应修正提供了一种可能的新途径。     

Incorporation of neural network analysis into a technique for automatically sorting lightweight metal scrap generated by ELV shredder facilities

In an attempt to improve the technique of automatic sorting of lightweight metal scrap by sensing apparent density and three-dimensional shape, realized by the combination of a three-dimensional (3D) imaging camera and a meter to weigh a moving object on a conveyor belt, neural network analysis was integrated into the scrap identification algorithm, and its effect on the sorting accuracy of this technique was examined using approximately 1750 pieces of scrap sampled at three different end-of-life vehicle (ELV) shredder facilities. As a result, the newly developed algorithm, in which an unknown fragment is identified by passing through two discriminant analyses and one neural network analysis, was demonstrated to greatly decrease the time required for data analysis to prepare the identification algorithm without reducing the sorting accuracy. The average sorting accuracy for a mixture of three types of lightweight metal fragments was found to be 85%, based on the fact that the fist-sized fragments of cast aluminum, wrought aluminum, and magnesium sampled at the three ELV shredder facilities had similar apparent densities and 3D shapes. It was also suggested that still higher sorting performance is possible by repeating the procedure of modifying the database and re-learning of the neural network in the identification algorithm.