水杨基荧光酮分光光度法与石墨炉原子吸收法测定饮用水中钛的比较

【目的】对水杨基荧光酮分光光度法（A法）与石墨炉原子吸收法（B法）测定饮用水中钛进行比较,从而建立一种简便、快速、高灵敏度的测定饮用水中钛的方法。【方法】水杨基荧光酮分光光度法按照GB/T5750.6-2006《生活饮用水标准检验方法-金属指标》17.2的有关规定进行。石墨炉原子吸收法按照仪器厂家推荐条件进行。【结果】两种方法均具有良好的线性关系、准确度和精密度,所测得的结果在统计学上无显著性差异。【结论】A法干扰因素多,操作繁琐。B法则操作简单,灵敏度高,精密度和准确度均符合分析要求,适宜推广应用。     

Climatology of Equatorial Stratospheric Ozone and Trends over Lagos (6.6°N, 3.3°E)

Dobson spectrophotometer total ozone observations made at Lagos (6.6°N, 3.3°E) between 1993 and 2004 are analyzed in order to derive climatology and variability of equatorial stratospheric ozone and ozone trends. Our results demonstrate clear seasonal changes which maximizes in June and July with typical value of 259 DU. Ozone variability is essentially low, within 0–6%. Detailed comparisons with the satellite measurements from 1997–2002 indicate considerable disagreement. The spectral analysis of ozone data reveals strong quasi-biennial signatures. Dobson ozone trend (1993–2004) is found to be roughly +2.0 ± 1.0% per decade; quantitatively consistent with previous trends results except for sign.     

气压制动系统ABS双模糊控制仿真分析

根据气压制动系统的结构和性能特性,建立中型载货汽车动力学模型和气压制动系统模型。根据基于滑移率控制的ABS控制流程,在Matlab/Simulink环境内建立适合气压ABS的双模糊控制器。为研究双模糊控制方法在气压ABS系统中的控制效果,利用建立的模型和控制器,仿真双模糊控制气压ABS的制动过程,并把仿真结果与相同条件下逻辑门限值控制的气压ABS制动仿真结果进行对比。结果表明,双模糊控制方法在控制精度和控制柔性等方面具有较大的优势。     

几种新型热作模具钢的性能对比研究

利用洛氏硬度计和冲击试验机对SDCM1、SDCM2、SDCM3、SDCM4等4种热作模具钢作硬度和冲击试验,得到了这4种钢的最佳热处理工艺参数。利用BAHR DIL805A相变仪、SDT CM600热重/DSC联用热分析仪、LFA 457激光导热系数测量仪等设备测量了这4种材料的膨胀系数、比热和热扩散系数。结果表明:SDCM3具有最佳的综合力学性能,SDCM4在这4种材料中具有最好的热作模具性能。     

设计变更方案比选与造价控制

本文通过对局部设计变更方案的优化与比选实例,探讨工程设计变更造价控制的一些做法。     

两种生产HDPE的催化剂应用对比分析

对比分析了国产BCH催化剂与国外同类催化剂的基本物性和工业应用等方面，指出了各自的优缺点，对国产BCH催化剂今后发展和工业应用有一定指导作用。     

Activation cross sections of the Yb(p,xn)Lu reaction for indirect production of the therapeutic radionuclide Yb

Activation cross sections of the ^natYb(p,xn)¹⁶⁹Lu reaction have been measured for the first time up to 70 MeV to investigate the production possibility of the radionuclide ¹⁶⁹Yb through decay of its parent ¹⁶⁹Lu. The cross sections were measured using the stacked foil irradiation technique and gamma spectrometry. The experimental data were compared with the results of the ALICE-IPPE theoretical model code. Different production routes were compared for the internal radiotherapy related radioisotope ¹⁶⁹Yb. Above 30 MeV proton energy the integral yield of the ^natYb(p,xn)¹⁶⁹Lu reaction is higher than that of the earlier investigated ¹⁶⁹Tm(p,n)¹⁶⁹Yb, ¹⁶⁹Tm(d,2n)¹⁶⁹Yb, ^natEr(α,xn)¹⁶⁹Yb, ^natYb(α,x)¹⁶⁹Lu and ^natHf(p,x)¹⁶⁹Lu reactions at the equivalent particle energies.     

Research scene

This opinion survey about the future of international construction concerns several time horizons, but only the five-year horizon is discussed in this paper. The analysis focuses on construction market attractiveness - a measure obtained by combining opinions about the rate of growth, profitability and openness to foreign competition - and construction industry competitiveness with respect to both services and materials. The results of the survey rank attractiveness of construction markets by country and city. The analysis of competitiveness of construction services and materials largely points to the same countries and indicates some important medium-term trends in the international construction market.

Cette étude d'opinions sur l'avenir de la construction internationale s'intéresse à plusieurs horizons mais seul l'horizon à 5 ans est examiné dans ce document. Cette analyse se concentre sur l'attractivité du marché de la construction - que l'on mesure en combinant les opinions sur le taux de croissance, la rentabilité et l'ouverture à la concurrence internationale et sur la compétitivité de cette industrie en termes de services et de matériaux. Les résultats de l'étude classent l'attractivité des marchés de la construction par pays et par ville. L'analyse de la compétitivité des services et des matériaux de construction met nettement en eéidence les mêmes pays et indique certaines tendances à moyen terme qui se dessinent sur le marché de la construction internationale.     

Coke deposition mechanism on the pores of a commercial Pt-Re/γ-Al2O3 naphtha reforming catalyst

Coke deposition mechanism on a commercial Pt-Re/γ-Al₂O₃ naphtha reforming catalyst was studied. A used catalyst that was in industrial reforming operation for 28 months, as well as the fresh catalyst of the unit were characterized using XRD, XRF, and nitrogen adsorption/desorption analyses. Carbon and sulfur contents of the fresh and the used catalysts were determined using Leco combustion analyzer. The pore size distributions (PSD) of the fresh and the used reforming catalysts were determined using BJH and Comparison Plot methods. The Comparison Plot method produced the most reasonable PSDs for the catalysts. Through comparison of the PSDs of the fresh and the used catalysts, it was revealed that coke deposited on both micropores and mesopores of the catalyst at a constant thickness of 1.0 nm. The constant coke thickness on the catalyst pore walls in the naphtha reforming process (temp. ∼ 500 °C) implies that coke deposition reaction is the slow controlling step in comparison to the fast mass transfer rate of coke ingredients into the pores. The bulk density of the deposited coke on the used catalyst was calculated as 0.966 g/cm³.     

Rule-based personalized comparison shopping including delivery cost

Comparison shopping allows customers to reduce time and effort when searching for product information and prices. However, traditional comparison sites mainly compare product prices without using precise information on delivery cost. To overcome this limitation, we adopted a rule-based comparison shopping framework using the eXtensible Rule Markup Language (XRML) architecture, which computes the exact personalized delivery cost at comparison sites. The prototype ConsiderD, which was developed for this purpose, computes the exact delivery costs considering the shipping rules, destination, delivery speed, and shipping rates. The XRML architecture effectively maintains the consistency of formal rules with the original Web pages. To demonstrate the performance of rule-based comparisons, we conducted an experiment on the purchase of books based on real-world data from five leading online bookstores. This experiment shows that rule-based comparison can significantly outperform data-based comparison in terms of the total cost of product and delivery. We also found that the comparison of delivery cost is very important because the variance of delivery cost can be as big as the variance of book prices itself.