Anisotropic behavior of deep-drawn al 1017 alloy using Macroscopic tensile and cupping tests

This paper presents a macromechanical approach for the determination of microstructural integrity of aluminum 1017 alloy (vis-à-vis recrystallization, recovery, and grain growth). Tensile and cupping tests were carried out on cold-rolled 1.2 mm and 1.6 mm samples. The paper examines the variation of the plastic strain ratio, dislocation density, degree of deformation, and ultimate tensile strength of this alloy in relation to the orientation of rolling using macromechanically based stress and strain models.     

Influence of real-world engine load conditions on nanoparticle emissions from a DPF and SCR equipped heavy-duty diesel engine

The experiments aimed at investigating the effect of real-world engine load conditions on nanoparticle emissions from a Diesel Particulate Filter and Selective Catalytic Reduction after-treatment system (DPF-SCR) equipped heavy-duty diesel engine. The results showed the emission of nucleation mode particles in the size range of 6-15 nm at conditions with high exhaust temperatures. A direct result of higher exhaust temperatures (over 380 °C) contributing to higher concentration of nucleation mode nanoparticles is presented in this study. The action of an SCR catalyst with urea injection was found to increase the particle number count by over an order of magnitude in comparison to DPF out particle concentrations. Engine operations resulting in exhaust temperatures below 380 °C did not contribute to significant nucleation mode nanoparticle concentrations. The study further suggests the fact that SCR-equipped engines operating within the Not-To-Exceed (NTE) zone over a critical exhaust temperature and under favorable ambient dilution conditions could contribute to high nanoparticle concentrations to the environment. Also, some of the high temperature modes resulted in DPF out accumulation mode (between 50 and 200 nm) particle concentrations an order of magnitude greater than typical background PM concentrations. This leads to the conclusion that sustained NTE operation could trigger high temperature passive regeneration which in turn would result in lower filtration efficiencies of the DPF that further contributes to the increased solid fraction of the PM number count.     

Lipids Classes,Fatty Acids,Fat Soluble Vitamins,and Molecular Species of the Triacylglycerol of Baphia nitida and Gliricidia sepium Seed Oils

Oil was extracted from the seeds of B. nitida and G. sepium and evaluated for its fatty acid composition, lipid profile, fatty acid distribution, fat soluble vitamins, unsaponifiable matter content, and molecular speciation of triacylglycerol. C18:2 was the predominating fatty acid found in the oils of B. nitida (50.00 ± 0.20 g/100 g fatty acids) and G. sepium (32.20 ± 0.30 g/100 g fatty acids) while the neutral lipids were the dominating lipid class in the oils of B. nitida (95.50 ± 0.70 g/100 g oil) and G. sepium (98.00 ± 0.30 g/100 g oil). Molecular species with equivalent carbon chain number C₄₈ were mainly present in the oils of B. nitida (39.6 ± 0.2%) and G. sepium (33.4 ± 0.0%). Digalactosyldiacylglycerol was the major glycolipid found in B. nitida (54.08 ± 0.10%) while both digalactosyldiacylglycerol (34.47 ± 0.50%) and digalactosylmonoacylglycerol (43.71 ± 0.20%) were found to be dominantly present in the oil of G. sepium. Phosphatidylethanol amine was the most abundant phospholipid found in B. nitida (97.70 ± 0.10%) while lyso phosphatidylethanol amine was the most abundant in G. sepium (74.22 ± 0.30%). Vitamins A and E were the two fat soluble vitamins detected in both oils while the gas chromatography-mass spectrometry result of the unsaponifiable matters revealed the presence of phytol, dodecatrienol, campesterol, stigmasterol, beta sitosterol, beta amyrin, beta tocopherol, stigmast-7-en-3-ol, stigmast-4-en-3-one, and hydrocarbons.     

Synthesis of polyol from the seed oil of Lonchocarpus cyanescens as potential lubricant

Polyol was synthesised from the seed oil of Lonchocarpus cyanescens by epoxy ring opening reaction with 2‐ethylhexanol. The structural characterization was confirmed using Fourier Transform Infrared and Proton Nuclear Magnetic Resonance (¹HNMR). Linolenic (C18:3) and oleic (C18:1) acids are the dominant fatty acids in the seed oil of L cyanescens with an iodine value of 170.46 ± 1.00 g 100 g⁻¹. The finding of this study showed that the seed oil of L cyanescens can be used to synthesise polyol, which can be used as a starting material for lubricant. Copyright © 2012 John Wiley & Sons, Ltd.     

Study on the Mechanical Properties of Cast 6063 Al Alloy Using a Mixture of Aluminum Dross and Green Sand as Mold

The mechanical characteristics of 6063 aluminum alloy cast in a mixture of aluminum dross and silica sand as mold have been examined. The amount of dross in the green silica sand was varied in the range of 0?C80% with bentonite as binder. In all, 40 samples were cast, and 8 of these were left in the as-cast condition for control while 32 were first homogenized at 470°C for 6?h and then rolled in a two-high mill at ambient temperature to 10% reduction in one pass. The rolled samples were solution heat treated at 515°C for 8?h followed by normalizing, annealing, and quench tempering, respectively. The samples were then simulated and tensile behavior coupled with the evaluation of microhardness and microstructures developed. The results obtained demonstrate significant improvement in mechanical properties from 50% to 80% dross in the mold. Tensile strength increased to 177?MPa and 15% elongation compared with conventional 6063-T5 aluminum alloy with 145?MPa tensile strength and 8% elongation. The improvement in mechanical properties by the quench-tempered samples can be attributed to the inducement of fine and coherent Mg₂Si crystals within the matrix. Furthermore, the overall analysis of the proportion of dross to the size of cast show that about 64% of dross generated can be utilized as mold material.     

Pulverized coal particle ignition in a combustion environment with a reducing-to-oxidizing transition

A reducing-to-oxidizing (RO) environment is characteristic of what a coal particle experiences in the near-burner region of pulverized coal (pc) furnaces. The RO environment can influence early-stage coal combustion processes such as ignition, aerosol formation, and char burnout. However, fundamental studies have focused on either oxidizing conditions (mimicking the post-flame region) or reducing conditions (mimicking the devolatilization region). The effect of this RO environment on early-stage coal combustion has, until now, not been considered. Here, the role of this reducing-to-oxidizing environment on single-particle ignition is evaluated. Powder River Basin (PRB) sub-bituminous coal was used, with a particle size of 125–149 μm and two nominal gas temperatures of 1300 K and 1800 K. The experimental findings for purely-oxidizing conditions with 20 vol% oxygen are compared with those of reducing-to-oxidizing environment. Single particles were tracked using high speed, high resolution videography. Emission intensities of the particles were used to evaluate the prevailing ignition modes, and to determine the characteristic ignition and induction times in both oxidizing and reducing-to-oxidizing environments. Experimental findings show that homogeneous-to-heterogeneous mode of ignition is prevalent for purely oxidizing conditions for both nominal gas temperatures of 1300 K and 1800 K. However, hetero-homogeneous ignition is favored in reducing-to-oxidizing environment at 1800 K and heterogeneous ignition at 1300 K gas flame temperature. The reducing-to-oxidizing environment leads to longer ignition delay times of about 20% and 40% on average for 1300 K and 1800 K nominal gas temperatures respectively but shorter induction times than those of oxidizing condition. The results show that ignition behavior in a reducing-to-oxidizing post-flame environments can be quite different from those in oxidizing environments.     

Integrated data envelopment-thermoexergetic optimization framework for multicomponent distillation system with multiexergetic response in the robust parameter design procedures

Integrated exergetic, data envelopment analysis (DEA)-robust parameter design framework is proposed to optimize and select thermo-feasible multicomponent distillation system which is a herculean task through reported exergy analysis techniques. It attempts to reduce the thermodynamic computational search for optimal sequence and to handle the effects of variations. Conventional exergetic analysis obtained the thermo-responses, variations are smoothened by robust signal-to-noise ratio procedures, variable return to scale (VRS) partitioning is imposed prior to the efficiency determination by the facet VRS model and penalization coefficient model is employed to select the optimum. The numerical illustration reveals its specificity and provides vivid and panoramic insight into actual efficient systems and those that need improvement. This study shows that exergetic analysis when integrated with DEA and robust parameter procedures can interrelate adequately, efficiently and effectively to optimize multicomponent distillation process and can be applied for optimizing energy-intensive systems especially those with multi-response processes.     

Optical Spatial Modulation with Diversity Combiner in Dual-Hops Amplify-and-Forward Relay Systems Over Atmospheric Impairments

Wireless Personal Communications - In this paper, we analyzed a dual-hop optical spatial modulation channel state information-assisted amplified and forward (AF) relay system with spatial diversity...     

Entry qualifications and academic performance of architecture students in Nigerian Polytechnics: Are the admission requirements still relevant?

The competence of fresh graduates of architecture has been continuously criticized by the industry for inadequate knowledge. This is often blamed on the poor standard of education evidenced by poor performances in professional and degree/diploma examinations conducted by various schools of architecture in the country. Although, factors responsible for the scenario are well documented in the literature, most of these works are based on testimonial and circumstantial evidences relating to management of architectural education only. The aim of this paper is to investigate the relationship between entry qualifications and the performance of architecture students in Nigerian Polytechnics with a view to determining the relevance of current admission policy to architectural education in Nigeria. Data were obtained from official records in the Department of Architecture in four randomly selected polytechnics in the southwestern part of Nigeria. Pearson Product Moment Correlation (r) was used to test the hypotheses. Findings reveal weak relationship between the two variables (physics and mathematics). This is contrary to the expectations of most scholars and policy makers who opine that students' proficiency in these subjects would enhance their performance at higher levels. The paper traces the contradiction to the poor handling of public examinations and misconception of architecture as being pure science. It holds that if these requirements are still relied upon for the admission of students into schools of architecture, wrong candidates would continue to gain entry into the profession. The paper concludes by recommending certain measures that are capable of reversing the trend.