Effect of Boronizing on Operating Stability of Steel AISI 304L under Erosion Impact of Hard Particles

Metal Science and Heat Treatment - The effect of solid boronizing at 950°C for 2 and 4 h on the phase composition, microstructure, hardness and abrasive wear of steel AISI 304L is studied...     

Experimental study of a micro-scale sloped solar chimney power plant

Journal of Mechanical Science and Technology - Solar chimney power plants (SCPP) are structures that have the potential to generate a significant amount of electrical energy without harming the...     

Unsaturated flow phenomena in porous medium as in a trickling filter

The relationship between substrate removal efficiency and dispersion characteristics of biological filters was investigated. Flow measurements were made using tap water and a synthetic feed solution. The importance of changes in fluid regime with regard to the simultaneous transport and reaction within the biological filter was demonstrated. The effect of drop formation and breakage of liquid jets on substrate utilization was shown.     

Effect of weathering on the geomechanical properties of the Miocene basalts in Malatya,Eastern Turkey

Miocene volcanic rocks are widely exposed in the eastern Taurids, Turkey. The geomechanical properties and weathering degree of the Middle–Upper Miocene basalts were determined at the Boztepe dam site in Malatya, eastern Turkey. An engineering geology map of the Boztepe dam site was made and the joint sets and the degree of weathering determined in the field. The degree of weathering and RQD values were obtained on some 1,195 m of core which was then compared with a series of geomechanical tests including unit weight, porosity, water absorption, uniaxial compressive strength and compressive wave velocity. The geomechanical properties were compared with the weathering classifications of ISRM (Rock characterization, testing and monitoring, p 211, 1981) and Kilic (Environ Eng Geosci 4:475–483, 1999)      

Investigation of UV and I–V characteristics of high refractive index polymer thin film for optoelectronic applications

In this study, high refractive index polymer (HRIP) [poly(pentabromobenzyl methacrylate-co-glycidyl methacrylate)] was investigated to obtain its optical and electrical performance for optoelectronic applications. UV characteristics of the polymer in solution of tetrahydrofuran were obtained and optical band gap energy of the polymer was calculated as 3.8 eV. I–V characteristics of the polymer were investigated after HRIP thin film was prepared using spin coating technique. The electrical parameters such as barrier height Φ_Bo, ideality factor n and reverse saturation current I_o were extracted from the forward biasing I–V characteristics. At the same time, series resistance R_s and Φ_Bo were determined by using a modified Norde function combined with conventional forward I–V method.     

Designing of a powder compressing device with vibration and investigation of compressibility of MgO powders with this device

One of metal matrix composite (MMC) production methods is infiltration of liquid metal into preformed reinforcement. In this method, MMCs are produced by infiltration of liquid metal into preformed reinforcement using one of pressure, vacuum or pressureless (free) infiltration methods. For infiltration purposes, reinforcement materials in different figuration are preformed in desired shape and reinforcement volume ratio. In this study a vibration apparatus has been designed to compress the particulate reinforcement in a tube so that pressure or vacuum infiltration can be carried out. The compressibility of MgO powders with different sizes with this apparatus has also been investigated. It has been found that with this apparatus, it is possible to compress desired number of specimens uniformly at the same time and at the same ratio. It has also been determined that MgO powders can be compressed in different ratio due to particle sizes with this device. Compressing time of 3 min is enough to reach maximum compression ratio in MgO powders.     

Geobag Performance as Scour Countermeasure for Bridge Abutments

This paper presents observations and data from a sequence of laboratory experiments conducted to evaluate geobags as a countermeasure to protect bridge-abutment foundations from failure attributable to scour of the alluvial-river channel in which they are placed. Geobags comprise geotextile cloth bags filled with local sediment or concrete. The experiments focused on the performance of geobags placed as an apron around pile-supported wing-wall abutments retaining erodible embankments, and subject to live-bed and clear-water flow conditions. Though an apron of geobags is shown to substantially reduce or eliminate scour immediately at the abutment, the apron must be formed flexibly of linked geobags. Moreover, a performance concern is that the apron may shift scour to a location flanking or downstream of the apron, and in so doing imperil a nearby pier or riverbank. The experiments indicate the importance of protecting the embankment region beneath and immediately behind the abutment’s pile cap. Live-bed conditions proved to be the more critical for abutment protection, owing to the capacity of dunes to destabilize geobags around the edges of the apron. Design guidelines are given and include using current riprap configurations for sizing and placing geobags.     

Poly(methyl methacrylate)/POSS hybrid networks by type II photoinitiated free radical polymerization

A new strategy for organic–inorganic hybrid networks is presented through in‐situ Type II photoinitiated polymerization of methyl methacrylate with diethanolamino‐functionalized polyhedral oligomeric silsesquioxanes (POSS‐DEA). The diethanolamino groups are simply incorporated onto POSS nanoparticles by nucleophilic ring‐opening reaction of commercially available epoxycyclohexyl POSS and diethanol amine. The photoinitiated polymerization of methyl methacrylate in the presence of benzophenone as photosensitizer and POSS‐DEA as hydrogen donor leads to poly(methyl methacrylate) (PMMA)/POSS hybrid networks under UV light irradiation. The morphology and thermal properties of hybrid networks are investigated by using Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and transmission electron microscopy. The morphology results confirm that POSS cages are homogeneously distributed in PMMA matrix at the molecular levels, whereas the thermal analyses shows that the obtained hybrid networks have higher glass transition temperatures and better thermal stabilities compared to parent PMMA homopolymer. POLYM. COMPOS., 35:1614–1620, 2014. © 2013 Society of Plastics Engineers     

Reliability estimation of washing machine spider assembly via classification

This paper presents a study on the reliability estimation of the spider assembly of the front loading washing machine. To achieve the analytical certification of the current design of the spider assembly of the washing machine, fatigue life test, finite element analysis, physical experimentation, and a classification processes were conducted. First, the conventional finite element analysis and fatigue life analysis were conducted and their simulation results have been validated by physical experiments in this research. The probability of failure is estimated by a classification process. Specifically, the probabilistic neural network classifier is incorporated into the simulation process to reduce the number of finite element analysis calculations while ensuring the prediction accuracy of the failure probability. Based on the estimated failure probability and other structural analysis results, the margin of the performance of the spider assembly is fully identified.     

Cost assessment of concrete and steel types for office buildings: An exploratory study

This paper presents a set of regression models which incorporates concrete and steel types in modeling the costs of office buildings. To these ends, three typical office buildings with seven and 15 stories have been designed by the help of a commercial software taking into account the Turkish practice. In each project C-16, C-20, C-25, C-30 and C-35 concrete classes and S-220 and S-420 steel types were used for dimensioning purposes. Rough construction costs were then calculated for different combinations of concrete classes and steel types. The findings of the study revealed that column dimensions decrease following an increase in a particular concrete class. However, this decrease stops after C-30. Furthermore, an average cost difference of 16% was observed between the steel types S-220 and S-420.