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On The Role of Environment on Tensile Response and Fracture Behavior of A High Strength Alloy Steel
Get PDFIn this paper, the influence of exposure to an aggressive environment and concomitant degradation due to corrosion on tensile properties and fracture behavior of a high strength alloy steel in the fully annealed condition is presented and discussed. Cylindrical specimens, conforming to the specifications detailed in American Society for Testing and Materials standard (ASTM E8), were prepared for purpose of this study. A test method (GMW14872), developed by General Motors (Michigan, USA), for purpose of inducing controlled corrosion on the exposed surface, using a spray technique, was used for stimulating accelerated corrosion in an environmental chamber. This was done with the intent of establishing the influence of damage resulting from an exposure to aggressive environment on short-term mechanical properties of the chosen alloy steel. The deformed and failed samples of the chosen alloy steel were examined in a scanning electron microscope with the objective of establishing the conjoint influence of severity of environment, exposure time, nature of loading and intrinsic microstructural effects on tensile response and fracture behavior
Design and Simulation of a New Solar Paraboloid Dish Collector
No full textSolar energy utilization is vital for our society which faces the global warming problem and the increase in the prize of fossil fuels. Concentrating solar collectors are a promising technology for producing useful energy from the sun. In this study, an innovative concentrating collector with a paraboloid dish reflector is presented and simulated. The main idea of this collector is the use of a dish reflector for continuous heat production with a high concentration ratio. For this reason, a spherical receiver absorber with two linear insulated ducts is used. The cost of this system is relative low because there is not a glass cover but a tracking system is required. The final results show better performance than the typical collectors such as the flat plate collectors and the evacuated tube collectors, fact that makes this collector a promising solution. The design and the simulation are carried out with the commercial software Solidworks, in the flow simulation studio
STEM and other Fields of Study
Get PDFSince the 2008 stock market crash in the United States of America (USA), with the multinational effects around most of the world, there has been job losses and financial insecurity felt by most working people. The lack luster recovery and the drop of oil prices in the last year (which has stabilized in recent months), have not improved much this sense and need for financial security. Financial security is largely obtained if one helps one’s young adult offspring select a well-paying profession. The paper by the authors in 2007, compared the financial wisdom of selecting STEM jobs as opposed to other fields of study. Their hypothesis that “science, technology, engineering, and mathematics (STEM) related fields will have higher monthly income on average than communication, education, arts, and social science fields”, was demonstrated to be true. The monthly income based on specialty field was forecasted using 4 methods. Half of the methods were moving averages and exponential smoothing, and these were stationary series models. The other half was trend-based methods; regression analysis, and double exponential smoothing or Holt’s method. The authors showed that the moving averages forecast a difference in favor of STEM fields of 934.18 per month. Further, a 1060.3 in monthly salary was forecast via Holt’s method. More recent data by Forbes shows that the top paying jobs are No. 1 Drilling Engineer with median pay of 97,300 and No.3 Mining Engineer with median pay $71,300 a year. These STEM jobs do lead to the same conclusion today that jobs outside the STEM fields do not pay as well
Chemical Composition Control of Evaporated Cu2ZnSnS4 Solar Cells
Get PDFThis paper focuses on chemical composition issue of evaporated Cu2ZnSnS4 (CZTS) absorber and potential solutions to it. The chemical composition of the CZTS absorber was estimated by energy dispersive spectroscopy (EDS) and a solution-based Inductively Coupled Plasma Mass Spectroscopy (ICPMS). It discloses a chemical non-uniformity issue spatially on even the same sample and confirms Sn loss issue. It also reveals that substrate option affects composition control
Performance Characteristics of A Simulated Hybrid Solar-Photovoltaic-Thermoelectric System for Renewable and Direct Power Generation Applications
Get PDFAdvanced nonconventional renewable and alternative green energy technologies which are used for generation of electrical power have shown real promise and received renewed interest in recent years due to an increasing concern of environmental issues of greenhouse gas emissions, air pollution, and the limitations and conservation of natural energy resources. Solar-photovoltaic (PV) systems directly convert renewable solar energy into green electrical energy. However, their power production and efficiencies tend to decrease when operating at relatively higher temperatures. Therefore, reducing the temperature of PV modules using efficient cooling methods would improve their performances. Thermoelectric power generation (TEG) technology could be used to convert a portion of the waste-heat energy dissipated from PV systems, thus cooling them, and at the same time generates extra power. Hence, hybrid photovoltaic-thermoelectric power generation (HPV-TEG) systems integrate TEG modules with a PV module to form a more efficient power generation system. The main objective of this paper is to investigate the viability and performance characteristics of a hybrid HPV-TEG through detailed lab-simulated tests. Experimental results and in thermal images showed that the HPV-TEG system was able to generate more DC power than the solo PV system while operating at higher irradiance intensities and lower TEG’s inlet coolant temperature. At the irradiance of 615W/m2, the power generation from the hybrid HPV-TEG system increased by 4.1% compared to the solo PV system. The results also indicated that when the irradiance was increased to 750W/m2, the power generated from the hybrid system increased to approximately 8.6% higher than the power generated from the solo PV system at the same irradiance. The integration of the concentrators in the hybrid PV system increased the maximum power point by 23.3% compared to the hybrid PV system without concentrators
Effect of MgSO4 Solution on the Physicochemical and Mechanical Properties of OPC-Metakaolin and OPC-Metakaolin-Limestone Blends
Get PDFThis study aims to investigate the effect of MgSO4 solution on the durability of the pastes made of ordinary Portland cement (OPC) blended with 10, 20 and 30 wt.% metakaolin (MK) and the pastes made by partial substitution of metakaolin in the mix containing 30% metakaolin by 5 and 10 wt.% limestone (LS). All pastes were prepared using the suitable amount of water for standard consistency. The pastes cured in tab water for 28 days then divided into two sets; the first one continued for hydration in tab water up to two years. The second set was immersed in 5% MgSO4 solution for the same period of hydration. Compressive strength, chemically combined water content and free lime content of the two sets of the hardened cement pastes were determined and compared to each other. Also, mass change of the set samples immersed in sulphate solution was investigated. In addition, phase composition and microstructure of some selected samples in the two solutions were examined by using XRD and SEM techniques respectively. It was found that the paste made of (70% OPC + 20% MK + 10% LS) represent the most durable against sulphate attack
Structural, Morphological, Topographical Characterization of Titanium Dioxide Nanotubes Metal Substrates for Solar Cell Application
Get PDFHigh demand on energy conversion in DSSC, requires development of well-organized TiO2 nanotube structures because of their large surface area-to-volume ratio, superior lifetime and provision of optimal pathways for electron percolation. In this work multi-layered Titanium dioxide nanotubes (MTNTs) have been fabricated by an electrochemical anodization technique. MTNTs were annealed at 350‚°C, 450‚°C, 550‚°C and 650‚°C. The structural and morphological properties of the MTNTs have been evaluated by XRD, Confocal Raman Microscopy (CRM) through Large Area Scan (LAS), Depth Profiling (DP) and SEM analysis. SEM-EDX has been employed for element elucidation of TNTs. SEM analysis has revealed the change in surface with increase in annealing temperature. Moreover SEM analysis has revealed the presence of porous and MTNTs for the samples annealed at 350‚°C and 650‚°C with modal pore size of 35.56 nm and 31.05 nm respectively. EDX analysis has revealed that the fabricated MTNTs consist of Ti and O atoms. CRM has confirmed the presence of Anatase phase TiO2 with Raman vibration modes at 142.37 cm-1, 199.04 cm-1, 394.67 cm-1, 516.16 cm-1 and 639.29 cm-1with the Rutile phase TiO2 with Raman vibration modes at 445.26 cm-1 and 612.07 cm-1. The XRD analysis has revealed that the MTNTs consist of multiphase Anatase and Rutile phase depending on the annealing temperature. AFM has confirmed the existence of porous nano-tubular structure for all samples
Shaping and Geometrical Analysis of the Ring-type Test Samples Used in Dimensional Measurements by a Bench-Type Multisensor CMM
Get PDFThe routine measurements of various geometrical quantities in industrial applications are realized by use of a range of optical methods. Optical metrology is a dynamically developing area of the modern science and technology using a hardware solution from simple sensors to advanced computer-controlled measurement systems. In many specific applications dedicated measurement systems are required, which are characterized by much better metrological parameters and wider measuring capabilities than typical systems. Testing of such systems must be carried out on objects with similar properties as the actual objects produced in industrial conditions. The hybrid system for non-contact simultaneous assessment of the surface texture and dimension developed in Koszalin University of Technology (Koszalin, Poland) specially produced sets of ring-type samples with a variable external diameter φz=20.5-30±0.2 mm.
This paper presents theprogress of works related to the design, production and analysis of the geometrical dimensions of such sets of test samples prepared for dimensional assessment by using laser triangulation methods. All the stages of this work are all so described and detailed in this paper. These stages included: the determination of assumptions for the preparation of samples, the choosing and characterising of the materials used for samples, the machiningwith a specialized bench-type lathe SK-1, as well as the dimensional measurements used by simple hand measuring instruments and the advanced bench-type coordinate measuring machine Video-Check®-IP 250 produced by Werth Messtechnik GmbH. The results obtained, which were presented in the form of bar diagrams and detailing already discussed, confirmed the dimensional correctness of the machining that was carried out
Defects and Remedies in Stamping of Advanced High Strength Steels
Get PDFIn recent years, the use of advanced high strength steels (AHSS) in the automotive industry has increased due to their potential in reducing weight, leading to lower fuel consumption and carbon dioxide emissions. The AHSS structures would be the optimum choice for many applications; however, there are many defects to overcome in their stamping. In this present study, different types of defects and remedies of AHSS stampings are presented
Synthesis and Characterization of PVdF/PVP-Based Electrospun Membranes as Separators for Supercapacitor Applications
Get PDFElectrospun polyvinylidene fluoride (PVdF)/polyvinylpyrrolidone (PVP) nanofiber embedded with carbon black nanoparticles (<50nm) were fabricated and characterized for supercapacitor separators. Carbon black nanoparticles with different weight percentages (0, 0.25, 0.5, 1, 2, and 4wt%) were added to a mixture of N, N-dimethylacetamide (DMAC)/acetone and sonicated for a well dispersion. Then, PVdF and PVP were added, and the solution was heated on a hot plate to make a polymeric solution prior to the electrospinning process. The morphology of the electrospun nanofibers was characterized by scanning electron microscopy and transmission electron microscopy. Fourier transform infrared spectroscopy was carried out on the PVdF/PVP films to identify changes in the crystalline phase during the process. The annealed nanofibers samples were also examined by X-ray diffraction unit. These investigations demonstrated that the many physical properties were significantly improved, which may be useful for supercapacitor separators. Supercapacitors will become one of the most suitable energy storage devices in the near future, and the separator is one of the major components of the supercapacitors.Keywords: Electrospun Nanofibers, PVdF, carbon black nanopowders, characterization, supercapacitor separators