地铁隧道不同排烟风速对火灾烟气控制的模拟分析

以某地铁隧道过江段为研究对象,基于CFD数值模拟方法,采用大涡模拟火灾分析软件FDS对相同纵向风速条件下,排烟道内不同排烟风速对地铁列车火灾烟气控制效果的影响进行模拟对比分析,分析结果可为设计单位对在排烟风机的选取提供一定的参考。模拟分析的结果表明,当纵向风速设定为1m/s时,排烟风道内排烟风速为5m/s即能达到较好的地铁列车火灾烟气控制效果。     

警惕来自外太空的灾害

<正>强烈的太阳风暴并非地震与海啸等自然灾害的主要诱因,但它对航天、通信、电力等人类的高科技活动却会造成严重影响。美国国家科学院和美国宇航局2010年初郑重预警了2012—2014年太阳风暴将带来的影响。科学家们担忧,太阳的这一次猛然"苏醒",也     

谈露天煤矿的安全隐患与防范措施

＂安全为天、安全为本＂是生产、生活中永恒的主题。无论从事何种生产经营活动,都必须把安全作为一项基础工作来抓,处处体现＂安全第一、预防为主、综合治理＂的安全生产方针。     

Performance and efficiency of old newspaper deinking by combining cellulase/hemicellulase with laccase-violuric acid system

Performance and efficiency of old newspaper (ONP) deinking by combining cellulase/hemicellulase with laccase-violuric acid system (LVS) were investigated in this study. Brightness, effective residual ink concentration (ERIC) and physical properties were evaluated for the deinked pulp. Fiber length, coarseness, specific surface area and specific volume were also tested. The changes of dissolved lignin during the deinking processes were measured with UV spectroscopy. The fiber morphology was observed with environmental scanning electronic microscopy (ESEM). Experimental results showed that, compared to the pulp deinked with each individual enzyme, ERIC was lower for the cellulase/hemicellulase-LVS-deinked pulp. This indicated that a synergy existed in ONP deinking using a combination of enzymes. After being bleached by H₂O₂, enzyme-combining deinked pulp gave higher brightness and better strength properties. Compared with individual enzyme deinked pulp, average fiber length and coarseness decreased a little for the enzyme-combining deinked pulps. A higher specific surface area and specific volume of the pulp fibers were achieved. UV analysis proved that more lignin was released during the enzyme-combining deinking process. ESEM images showed that more fibrillation was observed on the fiber surface due to synergistic treatment.     

Noninvasive fetal genome sequencing: a primer

We recently demonstrated whole genome sequencing of a human fetus using only parental DNA samples and plasma from the pregnant mother. This proof-of-concept study demonstrated how samples obtained noninvasively in the first or second trimester can be analyzed to yield a highly accurate and substantially complete genetic profile of the fetus, including both inherited and de novo variation. Here, we revisit our original study from a clinical standpoint, provide an overview of the scientific approach, and describe opportunities and challenges along the path toward clinical adoption of noninvasive fetal whole genome sequencing. © 2013 John Wiley & Sons, Ltd.     

Seasonal Variation of Inorganic Nutrient Uptake by Heterotrophic Bacterioplankton in Jiaozhou Bay,North China

The distribution patterns and factors affecting uptake rates and turnover times of dissolved inorganic nutrients by heterotrophic bacterioplankton (HB) in Jiaozhou Bay were studied based on in situ surveys and laboratory culturing. The uptake rates of dissolved inorganic phosphorus (DIP) and dissolved inorganic nitrogen (DIN) by HB are limited by the temperature of the water and the concentration of dissolved organic carbon. The turnover times of DIP and DIN by HB are regulated by the concentrations of the nutrients and the numbers of HB, which show significant spatiotemporal variability in Jiaozhou Bay. HB may aggravate the P-limitation of phytoplankton by competing for phosphorus in summer in Jiaozhou Bay. HB play an important role in the biogeochemical cycling of nutrients and may increase the N:P ratio and the accumulation of DIN, thereby accelerating the imbalance of the N:P ratio in Jiaozhou Bay.     

Movement of lagoon-liquor constituents below four animal-waste lagoons

Movement of liquor constituents from animal-waste lagoons has the potential to degrade ground water quality. The depth of movement and concentrations of lagoon-liquor constituents in the soil underlying three cattle (Bos taurus)-waste retention lagoons and one swine (Sus scrofa)-waste lagoon were determined. Samples were taken by using a direct-push coring machine, dissected by depth, and analyzed for total N, organic C, CaCO3, pH, cation exchange capacity (CEC), texture, and extractable NO3, NH(4), P, Cl, Ca, Mg, K, and Na. Ammonium N concentrations were greatest in the upper 0.5 m of soil under all four lagoons with concentrations ranging from 94 to 1139 mg kg(-1). Organic N was determined to make up between 39 and 74% of the total N beneath all lagoons. The swine lagoon had 2.4 kg N m(-2) in the underlying soil whereas the cattle lagoon with highest quantity of N had 1.2 kg N m(-2) in the underlying soil. Although N concentrations decreased with depth, N was greater than expected background levels at the bottom of some cores, indicating that the sampling efforts did not reach the bottom of the N plume. Nitrate N concentrations were generally less than 5 mg kg(-1) immediately below the lagoon floor. In the uppermost 0.5 m of soil underlying the swine and three cattle lagoons, NH4+ occupied 44% and between 1 and 22% of the soil cation exchange sites, respectively. The depth of movement of N under these lagoons, as much as 4 m, may pose remediation difficulties at lagoon closure.     

胜利油田利用生化法处理含油泥砂研究

胜利油田含油泥砂中含油量较高,直接进行生物降解处理的难度较大,操作周期长,费用高。先采用化学方法处理再进行生物处理,这样既可实现原油的资源化,又可降低费用,提高处理速度及处理效果。实验结果表明:化学处理方法能够将含油泥沙的含油量由51.1%降低至3.1%,原油回收率达到94%以上;再经过48h的生物处理,其含油量降到0.18%,达到了国家规定的无害化排放标准(<0.3%)。