A Generalized Formula for Estimating Pure Alkenes Viscosity

Abstract

The importance of liquid viscosity in chemical process design makes it one of the most measured transport properties. Nevertheless, in the pure-component database, no experimental data on liquid viscosity for nearly 50% of the compounds are available. Therefore, prediction methods for liquid viscosity of alkenes over a wide range of absolute temperature for each components are necessary. Moreover, experimental data measured at lower temperatures are often extrapolated to higher temperatures with erroneous results. To improve liquid viscosity prediction of experimental data to temperatures and carbon numbers, we propose an empirical rule for estimating the viscosity of alkenes compounds. A predictive method, based physical properties (absolute temperature and carbon numbers) as its inputs, to correlate liquid viscosity by the statistical analysis is proposed. For a group of 19 compounds, the mean average absolute deviation was 4.6% for 118 data points. These values are better than other predictive methods and show that the statistical analysis model is stable and can be used to obtain good predictions for compounds that were not used in the model calibration.     

Sustainability assessment of flooring systems in the city of Tehran: An AHP-based life cycle analysis

In recent years, numerous attempts have been made to reduce the global environmental and associated socio-economic impacts of construction activities to achieve sustainable development goals. A sustainable system or activity refers to an eco-friendly, cost effective and socio-politically viable solution. This paper utilizes triple-bottom-line (TBL) sustainability criteria for the selection of a sustainable flooring system in Tehran (Iran). Three types of block joisted flooring systems – concrete, clay, and expanded polystyrene (EPS) blocks – have been investigated using life cycle analysis (LCA). Proposed approach provides a comprehensive evaluation system based on TBL criteria that are further divided into thirteen sub-criteria. It includes: (1) Environmental concerns (resource depletion, waste and emissions, waste management, climate change, environmental risk, embodied energy and energy loss); (2) Economic concerns (material cost, construction cost, and occupation and maintenance cost); and (3) Socio-political issues (social acceptance, vulnerability of area, and building weight). Analytical hierarchy process (AHP) is used as a multi-criteria decision making technique that helps to aggregate the impacts of proposed (sub)criteria into a sustainability index (SI) through a five-level hierarchical structure. Integration of AHP and LCA provides a framework for robust decision making that is consistent with sustainable construction practices. A detailed analysis shows that the EPS block is the most sustainable solution for block joisted flooring system in Tehran.     

The Nonconvergence of h-Refinement in Prolate Elements

Prolate elements are a “plug-compatible” modification of spectral elements in which Legendre polynomials are replaced by prolate spheroidal wave functions of order zero. Prolate functions contain a“bandwidth parameter” $c \ge 0 $ c ≥ 0 whose value is crucial to numerical performance; the prolate functions reduce to Legendre polynomials for $c\,=\,0$ c = 0 . We show that the optimal bandwidth parameter $c$ c not only depends on the number of prolate modes per element $N$ N , but also on the element widths $h$ h . We prove that prolate elements lack $h$ h -convergence for fixed $c$ c in the sense that the error does not go to zero as the element size $h$ h is made smaller and smaller. Furthermore, the theoretical predictions that Chebyshev and Legendre polynomials require $\pi $ π degrees of freedom per wavelength to resolve sinusoidal functions while prolate series need only 2 degrees of freedom per wavelength are asymptotic limits as $N \rightarrow \infty $ N → ∞ ; we investigate the rather different behavior when $N \sim O(4-10)$ N ～ O ( 4 ? 10 ) as appropriate for spectral elements and prolate elements. On the other hand, our investigations show that there are certain combinations of $N,\,h$ N , h and $c>0$ c > 0 where a prolate basis clearly outperforms the Legendre polynomial approximation.     

On the Issue of Incomplete and Missing Water-Quality Data in Mine Site Databases: Comparing Three Imputation Methods

Large water-quality databases are valuable for predicting mine drainage chemistry, identifying optimal measures for mitigation and remediation, and refuting/refining models and theories. However, such databases often have missing values due to periodic lack of sampling and analysis or input errors. These missing values lead to problems in machine learning and statistical analysis of water-quality data from mine sites. Using water-quality data collected from 1971 to 1994 from many locations at a copper-molybdenum-gold-silver-rhenium mine site, we compared three imputation methods to estimate missing water-quality data: iterative robust model-based imputation (IRMI), multiple imputations of incomplete multivariate data (AMELIA), and sequential imputation for missing values (IMPSEQ). These methods were evaluated based on mean absolute error, relative absolute error, and percent bias techniques. The results showed that IMPSEQ and IRMI are suitable to impute missing values in water-quality databases at mine sites, whereas AMELIA is not.     

Marine Water Quality Assessment Of Synthetic-Based Drilling Waste Discharges

Drilling muds or fluids used in drilling operations serve several functions: they lubricate the drill bit; maintain borehole pressure; clean and condition the hole; and flush rock cuttings to the surface. Drilling mud also adheres to rock cuttings, as can formation oil. Barite is used as a weighting agent, which approximately makes up approximately 33% of synthetic mud. It contains traces of heavy metals, which contribute to the toxicity of drilling waste. As environmental issues attract increasing public awareness, the treatment and disposal of spent drilling fluids and contaminated rock cuttings from drilling operations have become sensitive issues for offshore operations around the world. Within the last decade, the oil and gas industry has introduced synthetic-based drilling fluids as substitutes for oil-based fluids. This pollution prevention measure has been complemented by improvements in solid control systems technology. This paper adopts the current U.S. Environmental Protection Agency methodology for a hypothetical case study of an oil field on the East Coast of Canada to determine the water quality impacts of disposal of drilling wastes. The concentration of pollutants at the edge of the mixing zone in the water column and pore water are estimated and compared with Canadian water quality guidelines for protection of aquatic life.     

Numerical modelling of production from the Poihipi dry steam zone: Wairakei geothermal system,New Zealand

The Poihipi power station utilizes dry steam from a shallow zone near the margin of the Wairakei geothermal reservoir. The station has been in operation for several years, with daily variations in the fluid production rate following variations in time-of-day pricing of electricity. The corresponding varying pressure history provides a good database for testing models of the geothermal reservoir.     

An overview of air emission intensities and environmental performance of grey cement manufacturing in Canada

Air emissions generated in grey cement manufacturing originate primarily from the combustion of fossil fuels required to heat the kiln and the chemical reaction of raw materials in the pyroprocessing phase. Given that the kiln system is enclosed, air emissions generated, discharge from a single point source kiln stack. Unlike other industries, the point source kiln stack enables the cement sector to accurately monitor and record total air emissions. The largest contributors to air emissions from grey cement manufacturing are carbon dioxide (CO₂), oxides of nitrogen (NO _x ), sulphur dioxide (SO₂) and dust/particulate matter (PM). In Canada, grey cement manufacturing facilities are required to annually report these emissions through the National Pollutant Release Inventory (NPRI). Since CO₂, NO _x , SO₂ and PM are the largest contributors to air emissions, and Canadian grey cement facilities are required to report these emissions, combining NPRI data with annual grey cement production data allows for the development of intensity-based environmental performance indicators. Based on data provided by NPRI, in combination with industry production, we can better understand the environmental performance of Canada’s grey cement manufacturing. On the global stage, intensity-based performance measures provide a useful tool for comparison and demonstrate a strong environmental performance for grey cement production in Canada. As an energy intensive and trade exposed (EITE) grey cement manufacturing is vulnerable to unbalanced environmental policy, which may ultimately result in leakage of production and air emissions to developing countries.     

Scheduling and allocation in high-level synthesis using stochastic techniques

High-level synthesis is the process of automatically translating abstract behavioral models of digital systems to implementable hardware. Operation scheduling and hardware allocation are the two most important phases in the synthesis of circuits from behavioral specification. Scheduling and allocation can be formulated as an optimization problem. In this work, a unique approach to scheduling and allocation problem using the genetic algorithm (GA) is described. This approach is different from a previous attempt using GA (Wehn et al., IFIP Working Conference on Logic and Architecture Synthesis, Paris, 1990, pp. 47–56) in many respects. The main contributions include: (1) a new chromosomal representation for scheduling and for two subproblems of allocation; and (2) two novel crossover operators to generate legal schedules. In addition the application of tabu search (TS) to scheduling and allocation is also implemented and studied. Two implementations of TS are reported and compared. Both genetic scheduling and allocation (GSA) and tabu scheduling and allocation (TSA) have been tested on various benchmarks and results obtained for data-oriented control-data flow graphs are compared with other implementations in the literature. (A discussion on GSA was presented at the European Design Automation Conference Euro-DAC'94 in Grenoble, France, and TSA at the International Conference on Electronics, Circuits and Systems — ICECS'94 in Cairo, Egypt.) A novel interconnect optimization technique using the GA is also realized.     

Proximal femoral osteotomy as the primary operation for young adults who have osteoarthrosis of the hip

We report the results of proximal femoral osteotomy that was performed to treat osteoarthrosis in twenty-three consecutive young adults (twenty-five hips) who had a mean age of thirty-eight years (range, eighteen to fifty-three years). The mean duration of follow-up was seven years (range, two to twelve years). With conversion to a total hip replacement as the end point, the rate of survival at twelve years was 67 per cent (95 per cent confidence interval, 37 to 88 per cent). Four hips (16 per cent) were converted to a total hip replacement at a mean of eight years after the osteotomy. For the patients who did not have conversion to a total hip replacement, the mean score for pain, according to the system of Merle d'Aubigné and Postel as modified by Charnley, improved from 3.4 points preoperatively to 5.1 points postoperatively, the mean score for walking ability improved from 3.9 to 4.7 points, and the mean score for range of motion improved from 3.2 to 4.2 points. These results compare favorably with those following other forms of operative treatment of osteoarthrosis of the hip in young adults. In addition, the osteotomy does not preclude subsequent replacement arthroplasty if one is necessary.