Friction Reduction in Lubricated-MEMS with Complex Slip Surface Pattern

AbstractMany types of micro-electro-mechanical-system (MEMS) based products are currently employed in a variety of applications. However, high friction in these systems is a problem which limits the development of MEMS devices in which sliding contacts are involved. The aim of this research is to evaluate the effect of boundary slip on the hydrodynamic friction in a low load lubricated MEMS, in particular when boundary slip takes places in the certain region of the lubricated sliding contact, i.e. complex slip surface pattern. The effectiveness of the boundary slip in reducing friction is highlighted. The results indicate that the deterministic complex slip pattern has a beneficial effect on decreasing friction

Redesigning of 4 (Four) Blades Propeller Installed in a Wooden Fishing Boat in a Ship Yard in Tegal, Central Java Province

For design of marine propeller, the energy supply from marine engine to the propeller should be converted to thrust force with minimum losses. Furthermore, the unwanted vibration and cavitation due to the overlooking a detail calculation of the propeller should be prohibited for increasing the fuel efficiency and life-span of the propeller. In the last few decades, most of small and medium sized enterprises (SMEs) focusing their work on ship component industry in Central Java Province Indonesia provide the marine propeller to the ship manufacturer and ship repairmen in some shipyards in northern part of Central Java port. The design of the propeller is never been observed and optimized. The aim of the present work is to redesign the installed propeller on a wooden fishing boat with the new optimized design using B-Series propeller theory approach. The reverse engineering method uses three-dimensional scanner to obtain the geometrical data of the installed ship propeller. The new optimized propeller design is obtained from free software calculation based on the boat and engine specification. The comparison shows that the new optimized propeller design has a wider blade and larger pitch and increases 20% of the open water efficiency of the propeller performance at lower engine rotation. Keywords: B-series design, fishing boat, marine propeller, redesign, optimizatio

Carbon nanotube capacitance model in degenerate and nondegenerate regimes

In this work, fundamental results on carrier statistics in a carbon nanotube treated as a one-dimensional material are presented. Also the effect of degeneracy on the capacitance of the carbon nanotube channel in a carbon nan-otube field effect transistor is discussed. A quantum capacitance as well as a classical capacitance is revealed. Furthermore it is shown that for low gate voltage, the total capacitance is equivalent to the classical capacitance but for high gate voltage it is equivalent to the quantum capacitance. We predict that in the nondegenerate regime, the total capacitance is equivalent to the classical capacitance and that the quantum capacitance can be neglected, whereas only quantum capacitance needs to be taken into account in the calculation of the total capacitance in the degenerate regime

Animal fiber characterization and fiber loading effect on mechanical behaviors of sheep wool fiber reinforced polyester composites

© 2020 Taylor & Francis. This is an Accepted Manuscript of an article published by Taylor & Francis in Journal of Natural Fibers on 06/12/2020, available online: https://doi.org/10.1080/15440478.2020.1848743.This study presents animal fiber characterization and the influence of various fiber loadings on mechanical properties of sheep hair fiber-reinforced polymer (SHFRP) composites. The sheep hair fibers (SHF) characterization was carried out using X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FTIR), thermo-gravimetric analysis (TGA), scanning electron microscopy (SEM) and non-contact surface roughness machine. The functional group and chemical bond were analyzed using FTIR techniques. The crystallinity index and thermal stability of the SHF were characterized, using XRD and TGA techniques, respectively. The composites were fabricated using a compression molding technique and a varying weight percentage of 20, 30 and 40 fiber. The composite plates were cut into test samples according to ASTM standard methods for their mechanical (tensile, flexural and impact) behaviors to be extensively analyzed. The surface morphology of the fractured samples was examined with aid of an SEM. From the results obtained, it was evident that the SHFRP composite recorded a significantly increased tensile strength property when fiber loading was increased from 20 to 40 wt%. The optimum 40 wt% SHFRP composite sample recorded better flexural and impact strength, when compared with other counterparts. This was attributed to a better fiber-matrix interfacial adhesion, as established fromSEM micrographs.Peer reviewedFinal Accepted Versio

A Novel Signal Processing Method for Friction and Sliding Wear

© 2021 by ASME. This is the accepted manuscript version of an article which has been published in final form at https://doi.org/10.1115/1.4052063This current study proposed a new computationally efficient and comparatively accurate algorithm for calculating both static and dynamic coefficients of friction from high frequency data. Its scope embraced an application in a real-time friction-based system, such as active braking safety systems in automobile industries. The signal sources were from a heavy-duty reciprocating dry sliding wear test platform, focused on experimental data related to friction induced by stick-slip phenomena. The test specimen was a polytetrafluoroethylene (PTFE)-coated basalt/vinyl ester composite material, tested at a large scale. The algorithm was primarily aimed to provide scalability for processing significantly large tribological data in a real-time. Besides a computational efficiency, the proposed method adopted to evaluate both static and dynamic coefficients of friction using the statistical approach exhibited a greater accuracy and reliability when compared with the extant models. The result showed that the proposed method reduced the computation time of processing and reduced the variation of the absolute values of both static and dynamic frictions. However, the variation of dynamic friction was later increased at a particular threshold, based on the test duration.Peer reviewe

An Improved Method for Measuring Phthalates in Seawater With Blank Contamination Using GC-MS

Quantification of phthalates or phthalic acid esters (PAEs) might be problematic due to matrix overlap, auto-self absorbance and background scattering noise by the plastic lab materials although plastics have been reported in the release of PAEs. These materials (ambient air, reagents bottles, sampling devices, and various analytical instruments), are ubiquitous in the laboratory environment, thereby making it more difficult to reliably analyze of trace concentration of PAEs. Thus, in the current study, a straight forward and reliable protocol has been established for the analysis of PAEs including control of blank contamination, and the experimental conditions such as extraction time and temperature were optimized. The mass of PAEs in blank tests of selected materials ranged from 3±0.7 to 35±6 ng for liquid-liquid extraction (LLE) and from 5±1.8 to 63±15 ng for solid-phase extraction (SPE). For both extraction methods, higher blank values were measured for dibutyl phthalate (DBP) (35±6 ng, 12±3 ng), and DEHP (63±12 ng, 23±5 ng) in LLE and SPE, respectively. Average recoveries of PAEs in LLE were 90-97% and obtained with successive aliquots of 2 mL, 1 mL, and 1 mL dichloromethane (DCM). For SPE, recoveries up to 86-90% were achieved with successive aliquots of 5, 3, and 2 mL DCM at a sample flow rate of 5 mL min -1 . Under the optimized conditions, the method quantification limits (MQL) for PAEs was 10-20 ng L -1 for LLE and 10-35 ng L -1 for SPE. Moreover, the dissolved concentrations of PAEs from LDPE measured by the LLE method ranged < 1.5 to 5.83 ng cm -2, and those measured by SPE ranged from 1.0to256ngL -1 , in seawater samples of Sharm Obhur. The method has lower MQL values for LLE and SPE than average reported values of 10-100 ng L -1 and 30-100 ng L -1 , respectively

The Effect of High-Power and Low-Power Lasers on Symptoms and the Nerve Conduction Study in Patients With Carpal Tunnel Syndrome. A Prospective Randomized Single-Blind Clinical Trial

Introduction: Carpal tunnel syndrome (CTS) is the most common peripheral nerve entrapment. Various treatments have been suggested for CTS and there is no consensus on their superiority and the order of their use. Laser therapy is a non-invasive treatment method for many musculoskeletal diseases, including CTS. This study aimed to determine and compare the effect of high-power lasers (HPLs) and low-power lasers (LPLs) on pain severity, function, pinch strength, and nerve conduction study findings in patients aged 30-50 years with mild or moderate CTS. Methods: This is a prospective, randomized, single-blind clinical trial. The study population included 45 patients aged 30-50 years who came to the physical medicine and rehabilitation clinic of Shohada-e-Tajrish hospital and mild or moderate CTS was confirmed for them. Patients were randomly assigned to control, LPL therapy, and HPL therapy groups. Pain, function, pinch strength, and nerve conduction study findings were recorded in all groups before, immediately and 12 weeks after the treatment. All data were compared using SPSS version 21. Results: All groups showed improvement regarding pain, function, and pinch strength. Laser therapy showed significantly better results compared to a wrist splint, but no significant difference was seen between high-power and LPL therapy groups. Nerve conduction evaluation findings did not reveal any significant difference. Conclusion: Both the wrist splint and laser therapy can improve the symptoms of carpal tunnel syndrome. HPL therapy showed better results, although not significantly different from LPL therapy. © 2020. All rights reserved

Palm Date Fibers: Analysis and Enzymatic Hydrolysis

Waste palm dates were subjected to analysis for composition and enzymatic hydrolysis of their flesh fibers. The fruit contained 32% glucose and 30% fructose, while the water-insoluble fibers of its flesh consisted of 49.9% lignin and 20.9% polysaccharides. Water-insoluble fibers were settled to 55% of its initial volume in 12 h. The presence of skin and flesh colloidal fibers results in high viscosity and clogging problems during industrial processes. The settling velocity of the fibers was improved by enzymatic hydrolysis. Hydrolysis resulted in 84.3% conversion of the cellulosic part of the fibers as well as reducing the settling time to 10 minutes and the final settled volume to 4% of the initial volume. It implies easier separation of the fibers and facilitates fermentation processes in the corresponding industries. Two kinds of high- and low-lignin fibers were identified from the water-insoluble fibers. The high-lignin fibers (75% lignin) settled easily, while the low-lignin fibers (41.4% lignin) formed a slurry suspension which settled very slowly. The hydrophilicity of these low-lignin fibers is the major challenge of the industrial processes

Statistical investigation on anaerobic sulphate-reducing bacteria growth by turbidity method

In oil and gas industry, corrosion due to activity of microorganism is one of the main factors, which contribute to catastrophic structural failure. Previous study always linked Sulfate-Reducing Bacteria (SRB) upon the mechanism of Microbiologically Influenced Corrosion (MIC), as the major contributors. In this study, mechanisms of SRB genus D. vulgaris in terms of bacterial growth under influence of environmental factors were investigated. The growth of pure strain ATCC 7757 and SRB isolated from the soil in suspected areas in Peninsular Malaysia were investigated by using turbidity measurement. Results from the study were analyzed statistically to show the significant influence due to various environmental factors. The results agreed that variation of each environmental parameter tested gives strong influence upon bacterial growth for SRB strain individually