燃气管线周围密闭空间的潜在风险及预防

近年来发生了多起因燃气泄漏后积聚在密闭空间内引起爆炸的严重事故,对社会造成了恶劣影响。本文通过对几起事故的共性分析,提出消除或减少这种危害的几个措施与同行们交流。     

The SOLIDS 6G Mobile Network Architecture:Driving Forces,Features,and Functional Topology

With the large-scale commercial launch of fifth generation(5G)mobile network,the development of new services and applications catering to the year 2030,along wi...     

Phase stability and pyroelectricity of antiferroelectric PLZST oxide

Polarization and transmission electron microscopy studies of the Pb_0.97La_0.02(Zr_0.65Sn_0.22Ti_0.13)O₃ (PLZST) ceramics confirmed the antiferroelectric (AFE) nature of this material. The electric-field-induced ferroelectric (FE) phase has a lifetime much longer than the reasonable laboratory time scale at T?≤?60°C. The observed frequency dispersion of the dielectric constant reflects the competition between AFE and FE orderings. At high temperatures, the induced-FE phase reverses fast to the AFE phase. This process produces a pronounced pyroelectric current. The FE-to-AFE transition temperature can also be tuned by a dc bias field.     

Cursor momentum for fascination measurement

We present a very different cause of search engine user behaviors—fascination. It is generally identified as the initial effect of a product attribute on users’ interest and purchase intentions. Considering the fact that in most cases the cursor is driven directly by a hand to move via a mouse (or touchpad), we use the cursor movement as the critical feature to analyze the personal reaction against the fascinating search results. This paper provides a deep insight into the goal-directed cursor movement that occurs within a remarkably short period of time (<30 milliseconds), which is the interval between a user’s click-through and decision-making behaviors. Instead of the fundamentals, we focus on revealing the characteristics of the split-second cursor movement. Our empirical findings showed that a user may push or pull the mouse with a slightly greater strength when fascinated by a search result. As a result, the cursor slides toward the search result with an increased momentum. We model the momentum through a combination of translational and angular kinetic energy calculations. Based on Fitts’ law, we implement goal-directed cursor movement identification. Supported by the momentum, together with other physical features, we built different fascination-based search result reranking systems. Our experiments showed that goal-directed cursor momentum is an effective feature in detecting fascination. In particular, they show feasibility in both the personalized and cross-media cases. In addition, we detail the advantages and disadvantages of both click-through rate and cursor momentum for re-ranking search results.     

A combination process of mineral carbonation with SO2 disposal for simulated flue gas by magnesia-added seawater

The desulfurization by seawater and mineral carbonation have been paid more and more attention. In this study, the feasibility of magnesia and seawater for the integrated disposal of SO₂ and CO₂ in the simulated flue gas was investigated. The process was conducted by adding MgO in seawater to reinforce the absorption of SO₂ and facilitate the mineralization of CO₂ by calcium ions. The influences of various factors, including digestion time of magnesia, reaction temperature, and salinity were also investigated. The results show that the reaction temperature can effectively improve the carbonation reaction. After combing SO₂ removal process with mineral carbonation, Ca²⁺ removal rate has a certain degree of decrease. The best carbonation condition is to use 1.5 times artificial seawater (the concentrations of reagents are 1.5 times of seawater) at 80°C and without digestion of magnesia. The desulfurization rate is close to 100% under any condition investigated, indicating that the seawater has a sufficient desulfurization capacity with adding magnesia. This work has demonstrated that a combination of the absorption of SO₂ with the absorption and mineralization of CO₂ is feasible.     

山楂后贮条件对山楂酒品质和风味的影响

该实验将鲜山楂密封贮藏于15 ℃、25 ℃和35 ℃,研究贮藏温度和时间对山楂酒品质和风味成分的影响。结果表明,相同贮藏时间条件下,随贮藏温度在15～35 ℃范围内升高,山楂酒pH值上升,总酸、柠檬酸和L-苹果酸含量降低,酯类含量升高。25 ℃条件下贮藏5 d,山楂酒pH值上升0.08,总酸、柠檬酸和L-苹果酸含量分别降低1.39 g/L、822.03 mg/L和154.83 mg/L,酯类物质含量升高49.7 mg/L;35 ℃条件下贮藏4 d,山楂酒pH值上升0.03,总酸、柠檬酸和L-苹果酸含量分别降低1.04 g/L、887.60 mg/L和164.88 mg/L,酯类物质含量升高25.8 mg/L。因此,25～35 ℃密封贮藏,可有效降低山楂酒中柠檬酸和L-苹果酸含量,升高酯类物质含量,改善山楂酒的风味与口感。     

某铀矿石微生物浸铀酸度试验

在其他条件一致,酸化酸度分别为10,20,30 g/L的条件下,采用柱浸方式对某铀矿石进行酸预浸-微生物浸铀对比试验,探索低酸耗、少板结、高浸出率的微生物浸铀工艺参数,为工业化堆浸应用提供参考。试验结果表明,3种酸化条件下,铀的最终浸出率接近,分别为96.14%,94.88%和98.25%,而耗酸率分别为8.23%,9.24%,9.67%,采用酸度为10 g/L的酸液酸化时耗酸率最低。     

某铁精矿浮选柱脱硫试验研究

采用浮选柱对某铁矿选矿厂生产的含硫量超过0.4%的磁铁矿精矿进行了脱硫试验研究。通过实验室浮选柱系统试验,确定了较理想的试验参数:磨矿细度-200目占96.8%以上,黄药用量240 g/t,硫化钠用量800g/t,硫酸铜用量200 g/t,2#油用量200 g/。t在此条件下,浮选柱经一次分选能够将铁精矿中硫含量降至0.084%。而浮选机经一次粗选、两次精选、一次扫选,所得铁精矿中硫品位仍在0.20%以上。     

Stress evolution with time and space during mining of a coal seam

Mining of the upper protective coal seam is widely practiced in China for coal mine safety, but relief gas may present a new risk of blasting. To control the relief gas effectively, a strain-soften model was built by FLAC^3D software to investigate the stress evolution during the process of mining the upper protective coal seam. The results show that the abutment stress changes rapidly within 10 m in front of the coal face, and the maximum abutment stress is approximately twice the original when the coal seam is mined 20–30 m. The abutment stress should break the rock mass and cause the gas to flow easily. In the stable mining period, the change trends of the x-stress and z-stress are different, and these should also pre-break the rock mass. The stress distributions of the rock mass at different distances under the protective coal seam are different, especially near the coal face, which should greatly affect the gas flow when the space of the protective and protected coal seams change over a large range. The relief angle also changes over a large range, increasing to a maximum approximately 30 m behind the coal face, and it decreases gradually when it is far away from the protective coal seam. The results are helpful for designing the coal face of protected coal seams and borehole layouts to control the relief gas.