Geotechnical properties of steel slag aggregates: Shear strength and stiffness

Steel slag is an industrial by-product formed in the furnace during the steelmaking process. Electric arc furnace slag (EAFS) and ladle furnace slag (LFS) are the primary by-products of steelmaking from steel scraps. This research evaluates the physical, geotechnical and engineering properties of LFS, EAFS and a blend comprising 50% LFS and 50% EAFS (LFS50 + EAFS50) through laboratory testing. The specialized laboratory tests undertaken in this study include California bearing ratio (CBR) and unconfined compressive strength (UCS) tests, direct shear tests (DSTs), consolidated drained (CD) triaxial tests and repeated load triaxial (RLT) tests. The shear strength responses of the steel slag were found to vary with the dilatancy-induced peak strength of the LFS and the LFS50 + EAFS50 mixture and the dilatancy-associated strain-hardening behavior of the EAFS. Based on the high shear strength parameters and the adequate stiffness that were attained, the steel slag was found to have the potential for usage as a geo-material. LFS and LFS50 + EAFS50 were well-graded and had high CBR values, which would deem them suitable for roadwork applications. EAFS, however, was found to be poorly graded and to have relatively lower CBR values, which would deem it suitable for less stringent applications such as engineering fill and pipe bedding. The viability of using these by-products as geo-materials in civil infrastructures can transform these current waste by-products, particularly LFS, from being stockpiled at steel company plants to being used as alternative green material.     

Modification of the cyclone separator geometry for improving the performance using Taguchi and CFD approach

ABSTRACT

The cyclone separator performance has been affected by its high-pressure drop. The main geometric ratios such as outlet diameter, inlet width and inlet height and total height have been preferred to reduce the pressure drop and improve the performance of cyclone separator. These standard geometric values have been altered with the aid of design of experiment technique by Taguchi method for reducing the pressure drop. This changed new design produce low-pressure drop compared with the standard cyclone separator. Moreover, the collection efficiency of the new design is high when compared with standard cyclone separator. The pressure drop, Euler number, cut-off diameter and efficiency of the standard and new cyclone separator have been compared with the results of mathematical and computational fluid dynamics technique (CFD). The Reynolds stress turbulence model and discrete phase model have been used for simulating the cyclone separator in CFD. An acceptable agreement has been obtained between these results.     

Crystal structure,optical and thermal studies of a new organic nonlinear optical material: l-Histidinium maleate 1.5-hydrate

A new organic nonlinear optical material l-histidinium maleate 1.5-hydrate (LHM) with the molecular formula C₁₀H₁₆N₃O_7.5 has been successfully synthesized from aqueous solution by slow solvent evaporation method. The structural characterization of the grown crystal was carried out by single crystal X-ray diffraction at 293(2) K. In the crystal, molecules are linked through inter and intramolecular NH?O and OH?O hydrogen bonds, generate edge fused ring motif. The hydrogen bonded motifs are linked to each other to form a three dimensional network. The FT-IR spectroscopy was used to identify the functional groups of the synthesized compound. The optical behavior of the grown crystal was examined by UV–visible spectral analysis, which shows that the optical absorption is almost negligible in the wavelength range 280–1300 nm. The nonlinear optical property was confirmed by the powder technique of Kurtz and Perry. The thermal behavior of the grown crystal was analyzed by thermogravimetric analysis.     

Regiospecific analysis of fractions of bovine milk fat triacylglycerols with the same partition number

Bovine milk fat was fractionated using preparative reversed-phase high-performance liquid chromatography. The conditions consisted of two successive linear gradients of acetonitrile and tert-butylmethylether, followed by a final isocratic mixture of the two eluants, leading to triacylglycerols grouped by their partition number (PN). Fractions corresponding to partition numbers 32 to 50 were isolated and analyzed for fatty acid distribution between sn-1,3 and sn-2 positions by Grignard degradation. Results showed that the fatty acid distribution in milk fat triacylglycerols is nonrandom. The distribution of short-chain fatty acids, stearic (predominantly at sn-1,3 position) and palmitic (predominantly sn-2 position), did not change with triacylglycerol size. Medium-chain fatty acids were predominantly located at sn-2 position, but their proportion at this position decreased with triacylglycerol size. Oleic acid distribution was also size-dependent in that it was located in high proportions at sn-2 position in smaller triacylglycerols and vice versa. Results also showed that the sn-2 position was more unsaturated than sn-1,3 position in the PN range from 32 to 40, but it was more saturated in triacylglycerols with higher PN.     

Worst‐case design of subsea production facilities using semi‐infinite programming

The problem of designing novel process systems for deployment in extreme and hostile environments is addressed. Specifically, the process system of interest is a subsea production facility for ultra deepwater oil and gas production. The costs associated with operational failures in deepwater environments are prohibitively high and, therefore, warrant the application of worst‐case design strategies. That is, prior to the construction and deployment of a process, a certificate of robust feasibility is obtained for the proposed design. The concept of worst‐case design is addressed by formulating the design feasibility problem as a semi‐infinite optimization problem with implicit functions embedded. A basic model of a subsea production facility is presented for a case study of rigorous performance and safety verification. Relying on recent advances in global optimization of implicit functions and semi‐infinite programming, the design feasibility problem is solved, demonstrating that this approach is effective in addressing the problem of worst‐case design of novel process systems. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2513–2524, 2014     

Atmospheric Composition and Quality of Fresh Mushrooms in Modified Atmosphere Packages As Affected by Storage Temperature Abuse

Mushrooms (Agaricus bisporus) were packaged in 4-liter modified atmosphere (MA) containers, and a steady-state atmosphere of 5% and 10% was maintained at 4 °C. Temperature was fluctuated from 4 °C to 20 °C during 12-d storage period in cycles: 2 d at 4 °C followed by 2 d at 20 °C. Temperature increase during fluctuations caused anoxic atmospheres both in O₂ (1.5%) and CO₂ (22% to 10%). The quality of mushrooms stored under temperature fluctuating regime was severely affected as indicated by extensive browning, loss of firmness, and the level of ethanol in the tissue compared to mushrooms stored at constant temperature. It was clear that temperature fluctuation, even if it should occur once, can seriously compromise the benefits of MA packaging and safety of the packaged produce.     

Increasing short-chain fatty acid yield during lipase hydrolysis of a butterfat fraction with periodic aqueous extraction

Factors affecting the release of short-chain fatty acids during hydrolysis of a butterfat fraction with a 1,3-positional and short-chain-specific Penicillium roqueforti lipase were investigated. When a short-chain triglyceride fraction was used as substrate, as opposed to whole butterfat, the ratio of desirable flavor short-chain free fatty acids (FFA) to undesirable medium-chain FFA in the FFA fraction increased from 0.75 to 1.80. However, with both substrates, FFA accumulation eventually led to lipase inhibition and limited the total amount of triglyceride hydrolysis. This inhibition phenomenon was principally due to product inhibition. Periodically extracting the FFA with a buffer solution minimized this inhibition phenomenon, thereby significantly increasing lipase activity and the degree of triglyceride hydrolysis. Thus, on-line extraction of FFA in lipase reactors has the potential of greatly increasing system productivity.     

Nickel-based,binary-composite electrocatalysts for the cathodes in the energy-efficient industrial production of hydrogen from alkaline-water electrolytic cells

Ni-Mo, Ni-Zn, Ni-Co, Ni-W, Ni-Cr and Ni-Fe, binary-composite, codeposit surface coatings on mild-steel substrates were prepared by conventional electrodeposition techniques. The chemical compositions and the micrographic surface features of these coatings are reported. The utility of these coatings as cathodes in laboratory-scale alkaline-water electrolytic cells was assessed by polarisation techniques. The trend in their electrocatalytic activities ranks in this order: Ni-Mo>Ni-Zn>Ni-Co>Ni-W>Ni-Fe>Ni-Cr. The electrocatalytic activity of these coatings is very significant when compared with the data on conventional mild-steel cathodes currently used in industry. The results obtained experimentally are presented. A brief discussion is also included to highlight their utility.     

Evaluating the effect of vehicle modification in reducing injuries from landmine blasts. An analysis of 2212 incidents and its application for humanitarian purposes

Introduction

Anti-vehicle (AV) mines have been laid indiscriminately in conflict areas for the past 100 years. With an indeterminate life-span they continue to pose a significant threat to the civilian population, as well as restrict the movement of people, aid and goods to vulnerable populations. The aim of this study was to analyse unique casualty data from 2212 mine incidents to determine if simple vehicle modifications can reduce fatality and injury rates from mine explosions.

Method

We analysed casualty data from the Rhodesian War (1972–1980), to assess the effects of basic vehicle modifications (V-shaped hull, increased ground clearance, widened axles, heavy vehicles and blast deflectors) on injury rates. A multinomial regression statistical model was developed for vehicle modifications and number of alterations to explore these effects.

Results

Incident data was available on 2212 vehicle mine incidents involving 16,456 people. The overall fatality rate was 3.3% (544/16,456) and the overall injury rate was 22.7% (3741/16,456). Explosions against mine-protected vehicles resulted in a fatality rate of 1.2% (150/12,919); occupants in unprotected vehicles sustained a fatality rate of 11.4% (395/3537). The injury rate in mine protected vehicles was 22.2% (2868/12,919) compared to 24.7% in unprotected vehicles (873/3537).Utilising a multinomial logistical-regression model, we show that each design feature significantly reduced fatality rate (from 45% in unprotected vehicles to 0.8% in protected vehicles); each of these designs had a cumulative effect in fatality reduction. In isolation, blast deflectors, whilst reducing fatality rates, increased injury rates.

Conclusions

Our data clearly demonstrates that simple vehicle modifications can have a significant effect on reducing fatality and injury rates from AV mine explosions. Given that the modifications described were produced using commercially available vehicles with basic engineering requirements, we believe that similar processes could be employed in post-conflict environments in a cost-effective manner.