对一种新型供热收费模式的探讨

在总结现有供热收费模式特点的基础上提出了一种新型的供热收费模式--三部制收费模式,给出了三部制收费模式的计算方法.     

徕卡TPS1200全站仪的常见故障排除与维护保养

徕卡TPS1200全站仪是近年来石油物探行业应用最为广泛的测量仪器之一。本文对TPS1200全站仪在使用中经常出现的故障现象进行了归纳分类,分析了故障产生的原因及解决办法,并对维修过程中所采取的措施进行了介绍。文中还介绍了全站仪的一些日常维护保养常识。     

双卡联动技术应用于油田加油站

双卡联动控制技术在电路设计上充分考虑了电磁兼容性以及生成交易记录的可靠性.通过对现场的应用测试表明,该系统功能完善,具有较强的适应环境能力,计量准确;适合于加油行业的应用,真正实现了卡机联动,提高了加油站的管理水平,保证了加油站的安全性.     

First principles study on the properties of p-type conducting In:SnO2

Detailed theoretical investigations on the structural, electronic and optical properties of p-type conducting In:SnO₂ have been conducted by first principle calculations. Analysis on the thermal stability via standard enthalpy of formation calculations shows that In:SnO₂ remains stable at very high In concentration, although the lattice constant expands in a distorted rutile structure with the increase of indium content. This can be attributed to the larger ionic radii and the one less 5p electron of In³⁺. Due to the differences in thermal stabilities of the structures with the same indium concentration, the preferred In³⁺ distribution is to occupy the Sn sites in different (110) slabs, followed by occupying the location in the same (110) slab with a maximized distance between indium ions. Indium element in SnO₂ introduces a band in the low energy region originated from the In 4d orbitals and an acceptor energy level slightly above the Fermi energy. While the large effective mass of the electron holes in the valence band results in the small p-type conductivity of In:SnO₂. The tiny changes in the conduction band and band gap lead to the invariability of the optical spectra in the ultraviolet-visible region. On the contrary, the dramatic enhancement of dielectric function, reflectivity and absorption in infrared region can be interpreted by the transition from the occupied states to the empty bands near E_f as well as the exciton effect. These features make In:SnO₂ a good candidate for applications such as transparent conducting materials, infrared reflecting materials and gas sensors.     

新型缓蚀剂对水性环氧涂料防腐性能的影响

新型无机缓蚀剂已成为目前研究的热点.国内外对磷酸盐系缓蚀剂的缓蚀机理和缓蚀效果的研究已很充分[1-2].但该类缓蚀剂也存在一定的缺点,如颗粒较粗大,在涂料中分散性能较差等[3].为解决这一问题,现在的主要发展方向是开发出高效、低价、高性能化、高同体化、水性化、微细粉末产品[4].复合磷钛粉就是基于这一要求发展起来的一类新型缓蚀剂.本文利用极化曲线对复合磷钛粉的缓蚀机理进行了初步的探索,并通过电化学阻抗技术研究了复合磷钛粉用量对涂层耐蚀件的影响.     

供电企业输变配电设备信息编码基本原则的探讨

系统地进行供电企业输变配电设备分类和编码是 MIS建设和计算机网络开发和应用急需解决的问题。从信息化的高度首次提出供电企业输变配电设备分类和编码的基本原则。这些原则可以作为电力企业建立信息资源管理和信息编码的指导。     

Optimisation of acid extraction of pectin from sweet potato residues by response surface methodology and its antiproliferation effect on cancer cells

The response surface methodology was employed to study the acid extraction of pectin from sweet potato residues. The effects of extraction temperature, extraction time, solution pH and liquid/solid ratio on yield and galacturonic acid content of pectin were investigated. Experimental data were fitted to quadratic polynomial models and analysed using appropriate statistical methods. The determined optimum conditions were extraction temperature 93 °C, extraction time 2.2 h, solution pH 1.7 and liquid/solid ratio (v/w) 30:1. Under these conditions, the experimental extraction yield and galacturonic acid content of pectin were 5.09% and 70.03% (w/w), which were in good agreement with predicted values, 5.08% and 69.40%, respectively. In addition, sweet potato pectin exhibited remarkable antiproliferation effects on human colon cancer cells HT‐29 and human breast cancer cells Bcap‐37 by 46.64% and 42.64% at 1.00 mg mL^?1 separately, indicating that it could potentially be used as a natural supplement in functional foods.     

Flammability limits of hydrogen-enriched natural gas

This paper reports both the lower and upper flammability limits of hydrogen-enriched natural gas with hydrogen fractions of 20%, 40%, 60% and 80% respectively as well as these of natural gas and hydrogen, measured by using a constant volume combustion chamber together with a high-speed schlieren photographic system. Based on investigating pressure rise history inside the combustion chamber as well as flame photos, the effect of hydrogen enrichment on the flammability characteristics is discussed. Our experimental results show that the flammability limits of methane-hydrogen mixtures can be used for hydrogen-enriched natural gas as long as their hydrogen fractions are the same. In this paper, the flammability data of methane-hydrogen mixtures available in the literature are reviewed. Correlations for both the lower and upper flammability limits of methane-hydrogen mixtures are summarized.     

ERIC-PCR identification of the spread of airborne Escherichia coli in pig houses

To understand the spread of microbial aerosols in pig houses, with Escherichia coli (E. coli) as indicator, the airborne E. coli in 4 pig houses and their surroundings at different points 10, 50 m upwind and 10, 50, 100, 200 and 400 m downwind respectively from the pig houses were collected, and the concentrations were calculated at each sampling point. Furthermore, the feces of pigs were collected to separate E. coli. The ERIC-PCR (Enterobacterial Repetitive Intergenic Consensus-Polymerase Chain Reaction) technology was used to amplify the isolated E. coli DNA samples, then the amplified results were analyzed by NTSYS-pc (Version 2.10) to identify the similarity of isolated E. coli. The results showed that the airborne E. coli concentrations in indoor air of the 4 pig houses (21-35 CFU m⁻³ air) were much higher than those in upwind and downwind air (P < 0.05), but there were no significant differences (P > 0.05) at downwind distances. The ERIC-PCR results also showed that 52.4% of the fecal E. coli (four houses being respectively 2/4, 50%; 2/4, 50%; 3/6, 50%; 4/7, 57.1%) were identical to the indoor airborne E. coli isolates, and there was more than 90% similarity between the majority of E. coli (50%, 21/42) isolated from downwind air at 10, 50, 100 and 200 m and those from indoor air or feces. It could be concluded that the aerosols in pig houses can spread to the surroundings, and thus effective measures should be taken to control and minimize the spread of microbial aerosols.