Study on the hydrolysis/precipitation behavior of Keggin Al13 and Al30 polymers in polyaluminum solutions

The hydrolysis/precipitation behaviors of Al³⁺, Al₁₃ and Al₃₀ under conditions typical for flocculation in water treatment were investigated by studying the particulates' size development, charge characteristics, chemical species and speciation transformation of coagulant hydrolysis precipitates. The optimal pH conditions for hydrolysis precipitates formation for AlCl₃, PAC_Al13 and PAC_Al30 were 6.5–7.5, 8.5–9.5, and 7.5–9.5, respectively. The precipitates' formation rate increased with the increase in dosage, and the relative rates were AlCl₃ ? PAC_Al30 > PAC_Al13. The precipitates' size increased when the dosage increased from 50 μM to 200 μM, but it decreased when the dosage increased to 800 μM. The Zeta potential of coagulant hydrolysis precipitates decreased with the increase in pH for the three coagulants. The iso-electric points of the freshly formed precipitates for AlCl₃, PAC_Al13 and PAC_Al30 were 7.3, 9.6 and 9.2, respectively. The Zeta potentials of AlCl₃ hydrolysis precipitates were lower than those of PAC_Al13 and PAC_Al30 when pH > 5.0. The Zeta potential of PAC_Al30 hydrolysis precipitates was higher than that of PAC_Al13 at the acidic side, but lower at the alkaline side. The dosage had no obvious effect on the Zeta potential of hydrolysis precipitates under fixed pH conditions. The increase in Zeta potential with the increase in dosage under uncontrolled pH conditions was due to the pH depression caused by coagulant addition. Al–Ferron research indicated that the hydrolysis precipitates of AlCl₃ were composed of amorphous Al(OH)₃ precipitates, but those of PAC_Al13 and PAC_Al30 were composed of aggregates of Al₁₃ and Al₃₀, respectively. Al³⁺ was the most un-stable species in coagulants, and its hydrolysis was remarkably influenced by solution pH. Al₁₃ and Al₃₀ species were very stable, and solution pH and aging had little effect on the chemical species of their hydrolysis products. The research method involving coagulant hydrolysis precipitates based on Al–Ferron reaction kinetics was studied in detail. The Al species classification based on complex reaction kinetic of hydrolysis precipitates and Ferron reagent was different from that measured in a conventional coagulant assay using the Al–Ferron method. The chemical composition of Al_a, Al_b and Al_c depended on coagulant and solution pH. The Al_b measured in the current case was different from Keggin Al₁₃, and the high Al_b content in the AlCl₃ hydrolysis precipitates could not used as testimony that most of the Al³⁺ was converted to highly charged Al₁₃ species during AlCl₃ coagulation.     

基于“反规划”视角的乡村旅游规划新途径探析

引入"反规划"思想,针对传统规划方法给乡村旅游带来的不利影响,强调"反规划"在乡村旅游规划中应用的必要性与可行性。通过与传统规划方法进行对比分析发现,当前乡村旅游规划中存在不少亟待解决的问题。同时,探析了"反规划"思想在乡村旅游规划中的运用,建立乡村旅游"反规划"发展模式为保障乡村旅游可持续性发展提供了理论依据。     

A methodology for assessing urban sustainability: Aalborg commitments baseline review for Riga, Latvia

Both the Aalborg Commitments and the guidance on integrated urban environmental management and sustainable urban transport plans proposed by the EU Thematic Strategy on the Urban Environment foresee a baseline review as the first step in developing integrated urban management plans and systems. A baseline review of urban sustainability undertaken in Riga reveals significant discrepencies between the sustainability criteria of the Aalborg Commitments and the: responsibilities and competencies of the municipal government and administration as defined by statutes; policy goals and measures defined in municipal planning documents; policy goals and measures defined in the Riga Development Plan. To better orient the mandate of the municipality towards sustainable development, municipal statutes should be supplemented to more fully reflect the issues defined by the Aalborg Commitments and should include sustainability as a goal. In order to strengthen the implementation of sustainable development specific policy goals, measures and targets should be formulated for all the Aalborg Commitments issues when revising existing municipal planning documents or developing a municipal sustainable development management plan. An analysis of the European Common Indicators and the State of the Environment in Riga 2001 indicators indicates that they can only partially fulfill a monitoring function for the implementation of the Aalborg Commitments. This highlights a need to better coordinate sustainable development initiatives at the European level. The methodology used for the baseline review in Riga is useful for assessing the status of urban sustainability when preparing integrated urban management plans or systems, but requires testing elsewhere. Readers should send their comments on this paper to BhaskarNath@aol.com within 3 months of publication of this issue.     

有限元数值模拟在巷道掘进中的应用研究

利用有限元分析进行数值模拟井下巷道分步开挖,对巷道应力、位移、应变进行了分析,改善了应力分布,有效减少了瓦斯涌出。本文利用数值模拟分步开挖并应用于实践,通过现场试验论证得出合理的分步开挖顺序改变了岩石应力集中,减少了瓦斯涌出量。     

航空公司安全目标控制的研究与改进

通过对航空公司安全目标控制现状的分析,得出了前馈控制中维修隐患查找不力,现场控制中员工自控和领导监督缺乏针对性、安全目标激励作用大打折扣、规章手册不利于查找,以及公司的反馈控制名存实亡等问题。并提出改进意见：针对维修隐患查找提出了新的查找机制;对员工安全指标排序,作为控制和监督的依据;引进目视管理,增强安全目标的激励作用;建议为维修员工提供能够快速查找相关手册项目的设备;使用滚动计划法制定安全计划,并借用其反馈框架,引入因果图查找产生偏差的原因。     

Are we planning for sustainable disaster recovery? Evaluating recovery plans after the Wenchuan earthquake

This article examines local recovery plans that were created in response to the Wenchuan earthquake and then suggests ways that planners can better apply the concept of sustainability to the recovery process. We utilize a plan evaluation protocol to analyze 16 recovery plans in counties and towns that were severely affected by the earthquake. We also conducted semi-structured interviews with public officials and planners, with the qualitative data gleaned from these interviews being used to supplement the plan quality assessment. The results reveal that local recovery plans do not appear to have incorporated sufficiently the concepts of sustainability. We conclude the paper with the following recommendations: emphasizing sustainability as a policy priority during vision and goal development; developing solid databases and planning techniques; designing a diversified set of regulatory- and incentive-based policy tools suitable for local governments; enhancing social and institutional learning; and further integrating multi-level and interagency governmental units.     

The conversion of chicken manure to biooil by fast pyrolysis I. Analyses of chicken manure,biooils and char by 13C and 1H NMR and FTIR spectrophotometry

Fast pyrolysis of chicken manure produced two biooils (Fractions I and II) and a residual char. All four materials were analyzed by chemical methods, ¹³C and 1H Nuclear Magnetic Resonance Spectrometry (¹³C and 1H NMR), and Fourier Transform Infrared Spectrosphotometry (FTIR). The char showed the highest C content and the highest aromaticity. Of the two biooils Fraction II was higher in C, yield and calorific value but lower in N than Fraction I. The S and ash content of the two biooil fractions were low. The Cross Polarization Magic Angle Spinning (CP-MAS) ¹³C NMR spectrum of the initial chicken manure showed it to be rich in cellulose, which was a major component of sawdust used as bedding material. Nuclear Magnetic Resonance (NMR) spectra of the two biooils indicated that Fraction I was less aromatic than Fraction II. Among the aromatics in the two biooils, we were able to tentatively identify N-heterocyclics like indoles, pyridines, and pyrazines. FTIR spectra were generally in agreement with the NMR data. FTIR spectra of both biooils showed the presence of both primary and secondary amides and primary amines as well as N-heterocyclics such as pyridines, quinolines, and pyrimidines. The FTIR spectrum of the char resembled that of the initial chicken manure except that the concentration of carbohydrates was lower.     

Impact of different public E&P policies on natural gas reserves and production in Pakistan

Low wellhead domestic gas prices over the past few years have led to the beginning of a shortage in natural gas reserves and production in Pakistan. Gas demand steadily rises in all sectors for being an economical fuel as compare to substitutes. In the view of foregoing consumption trend, the demand for gas is expected to grow with a higher pace during the 2010s. On the contrary, indigenous gas reserves are running out and cannot keep up with the demand. This paper examines the extent of upstream activities in different petroleum policy regimes. The wellhead price for indigenous gas is compared with the prices of alternatives (for example, gas import prices). In order to put the problem in perspective, the relationship between wellhead gas price and cumulative gas reserves in Pakistan are analyzed and we find that the looming gas shortage can be ameliorated in the short-run and eliminated in the long-run through incentivized wellhead price. To put it briefly, the idea is mooted to first take advantage of huge domestic reserves to ensure competitive consumer prices for gas. The findings are applicable to several other economies with under-developed natural resources.     

人-机-环境系统在武器装备研制中的应用

人-机-环境系统是把人、机、环境作为武器系统中的要素,从总体角度对武器装备进行全面规划和控制.人-机-环境系统在武器装备研制中的应用,将改变以往武器装备分散、孤立的研究局面,它把武器装备研制推向一个新阶段.综述了武器装备研制的不同阶段应用人-机-环境系统的基本思路.     

Mining and social development: Refocusing community investment using multi-criteria decision analysis

This paper addresses the question: How can mining companies assess social investment projects so that projects create value for the company and communities in which they operate? Mining companies are still wrestling with the limits of their responsibility in relation to social development even though they accept the business case for community investment at a general level. Fully aware of the practical hazards involved in taking an active role in facilitating local development, companies increasingly avoid methods that are overly paternalistic or assume the functions of the national or local governments. Gaining senior management's commitment to long-term social projects, which are characterised by uncertainty and complexity, is made easier if projects are shown to benefit the site's strategic goals. Case study research on large global mining companies, including interviews with social investment decision makers, has assisted in developing a Social Investment Decision Analysis Tool (SIDAT), a decision model for evaluating social projects. Multi-criteria decision analysis techniques integrating business planning processes with social impact assessment have proved useful in assisting mining companies think beyond seeking reputational benefits, to how they can meet their business goals and contribute to sustainable development.