Synergy of fiber length and content on free vibration and damping behavior of natural fiber reinforced polyester composite beams

This work addresses the results of experimental investigation carried out on free vibration characteristics of short sisal fiber (SFPC) and short banana fiber (BFPC) polyester composites. Influence of fiber length and weight percentage on mechanical properties and free vibration characteristics are analyzed. Composite beam specimen is fabricated with random fiber orientations at17 MPa compression using compression molding machine. Natural frequencies and associated modal damping values of the composite laminates were obtained by carrying out the experimental modal analysis. It is found that an increase in fiber content increases the mechanical and damping properties. For SFPC, 3 mm fiber length and 50 wt% fiber content yielded better properties, whereas for BFPC, 4 mm fiber length and 50 wt% fiber content was the best combination. Scanning electron microscopy was performed to study the interfacial mechanism.     

Platinum-nickel bimetallic catalyst doped with rare earth for enhancing methanol electrocatalytic oxidation reaction

Platinum (Pt) is often used as anodic catalyst for direct methanol fuel cell (DMFC). However, platinum is difficult to achieve large-scale application because of its low stability and high cost. In this work, the electrocatalytic activity and stability of the Pt-based catalyst for methanol oxidation (MOR) are significantly improved by adding Ce and Ni to the catalyst. Additionally, the rare earth element-Pr (Dy) is also chosen to be added into the catalysts for comparison. A series of PtMNi (M = Ce, Pr, Dy) catalysts are prepared by impregnation and galvanic replacement reaction methods using carbon black as support. The electrocatalytic mass activity of PtCeNi/C, PtDyNi/C, PtPrNi/C and Pt/C is 3.92, 1.86, 1.69 and 0.8 A mg_Pt⁻¹, respectively. The mass activity of these the above four catalysts after stability measurement is 3.14, 1.49, 1.27 and 0.72 A mg_Pt⁻¹. Among them, PtCeNi/C has the highest catalytic activity. These as-prepared catalysts are also characterized by various analyzing techniques, such as TEM, HRTEM, XRD, XPS, ICP-OES, STEM, STEM-EDS elemental mapping and line-scanning etc. It shows that PtCeNi/C exhibits best catalytic activity (3.92 A mg_Pt⁻¹) among the as-obtained catalysts, 4.9 times higher than that of commercial Pt/C (0.8 A mg_Pt⁻¹). PtCeNi/C is also with excellent anti-CO poisoning ability. The outstanding catalytic performance of PtCeNi/C for the MOR is mainly attributable to uniform-sized PtCeNi nanoparticles, uniform Ni, Ce and Pt element distribution, and electron interaction among Pt-, Ni- and Ce-related species (electron transferring from Pt to CeO₂).     

Phase relation studies in the CeO2–La2O3–Er2O3 system at 1500°C

Materials based on CeO₂–La₂O₃–Er₂O₃ system are promising candidates for a wide of applications, but the phase relationship has not been studied systematically previously. To address this challenge, the isothermal section of the phase diagram for 1500 °C was investigated. The phase relations in the CeO₂–La₂O₃–Er₂O₃ ternary system at 1500 °C were studied by X-ray diffraction and scanning electron microscopy in the overall concentration range. To study phase relationships at 1500 °C the as-repared samples were thermally treated in two stages: at 1100 °C (for 300 in air) and then at 1500 °C (for 70 h in air) in the furnaces with heating elements based on Fecral (H23U5T) and Superkanthal (MoSi2), respectively. The solid solutions based on various polymorphous forms of constituent phases and with perovskite-type structure of LaErO₃ (R) with orthorhombic distortions were revealed in the system. No new phases were found. The isothermal section of the phase diagram for the CeO₂–La₂O₃–Er₂O₃ system has been constructed. It was established that in the ternary CeO₂–La₂O₃–Er₂O₃ system there exist fields of solid solutions based on hexagonal (A) modification of La₂O₃, cubic modification of CeO₂ with fluorite-type structure (F), cubic modification Er₂O₃ and with perovskite-type structure of LaErO₃ (R) with orthorhombic distortions. The maximal solubility of ceria in LaErO₃ was found to be around ∼ 2 mol% CeO₂ along the section CeO₂–(50 mol % La₂O₃ –50 mol% Er₂O₃).     

Growth,characterizations, and the structural elucidation of diethyl-2-(3-oxoiso-1,3-dihydrobenzofuran-1-ylidene)malonate crystalline specimen for dielectric and electronic filters,thermal, optical,mechanical, and biomedical applications using conventional experimental and theoretical practices

Journal of Materials Science: Materials in Electronics - The single crystals of diethyl-2-(3-oxoiso-1,3-dihydrobenzofuran-1-ylidene) malonate (D23DYM) were grown successfully and efficiently by the...     

Review of mathematical models for health risk assessment: VII. chemical dose

The health risk assessment of chemical emissions from industrial facilities requires the mathematical modeling of a variety of processes, including transport and fate of chemicals in and between various environmental media, population exposure to these chemicals, their associated doses, and health effects. Several models are presently available to address these different components of the health risk assessment. Existing models were reviewed and recommendations are provided for the selection of models suitable for screening and refined risk assessments. This article reviews mathematical models for estimating chemical dose.     

Tribological behaviour of new chemically bonded PTFE polyamide compounds

Topic of the study is the formation of new PTFE polyamide materials by reactive extrusion. The new type of formed PTFE polyamide compound shows very good material properties. Recently it has been revealed that carboxylic acid groups exhibit a very high reactivity under polyamide melting conditions. PTFE micro powders functionalized by carboxylic acid groups are the base for the block copolymer formation in polyamide melts under defined process conditions. Such functionalized micro powders are formed from virgin PTFE by electron irradiation in the presence of oxygen. These new PTFE polyamide materials can be processed easily using commercial (common) process equipment like twin-screw extruders and injection molding. Many experimental investigations have been performed under dry sliding friction on PA 6, PA 6.6 and PA 12 compounds with PTFE weight portions between 3.3 and 50%. They show low coefficients of friction and low specific wear rates. The wear resistance of newly developed PTFE polyamide compounds is comparable with commercially available mechanically or physically produced PTFE and PEAK compounds.     

A hybrid firefly algorithm with particle swarm optimization for energy efficient optimal cluster head selection in wireless sensor networks

Neural Computing and Applications - Wireless Sensor Networks (WSN) are operated on battery source, and the sensor nodes are used for collecting the information from the environment and transmitting...     

An experimental inquisition of waste heat recovery in electronic component system using concentric tube heat pipe heat exchanger with different working fluids under gravity assistance

In the utilizing of the waste heat in the electronic components meets the power demand and energy utilization for the industries and domestic applications. To meet out this by the understanding and optimization of the waste heat utilization by a compact and cost effective device using heat pipe heat exchanger. This paper states with the design, fabrication, development, and observation of an experimental investigation of the heat pipe introduce in the concentric tube heat exchanger. Working fluids like Methanol, Acetone and heat transport fluid as water. The investigation is further extended by varying the inclination angles, mass flow rates, and temperatures of hot and cold fluid at inlet conditions. The influence of gravitational effect on the heat pipe heat exchanger is conducted for inclination angle from 10° to 80° and the maximum performance is obtained at 60° inclination angle. It is observed while acetone as working fluid there is an increase in 29.75% for effectiveness, 79.81% as heat transfer coefficient, 39.53% as heat transfer rate, 6.70% for Reynold's number and 10.52% decrease in thermal resistance than with methanol. It is concluded that the acetone exhibits better performance when related with methanol as a working fluid. These observations show the suitability of the designed concentric tube heat pipe heat exchanger for the utilization of waste heat dissipation in electronic component system.     

Characterization of reduced graphene oxide obtained from vacuum-assisted low-temperature exfoliated graphite

Microsystem Technologies - Graphene consists of sheets of two-dimensional allotrope carbons and is a basic element of graphite. Herein, reduced graphene oxide (rGO) were exfoliated from graphite...