Abstract:In recent decades, natural fibers have received attention of scientists and researchers due to their ecofriendly characteristics that qualify them as potential reinforcement in polymer composites in place of synthetic fibers. In this study, an experimental investigation has been conducted to evaluate the effect of orientation of fibers on mechanical properties of a newly developed bio-composite in which date palm fronds (DPF) are embedded as fibers in low-density polyethylene (LDPE) matrix. Three bio-composite sheets with orientations of 0°, 45° and 90°, respectively have been fabricated after the date palm fronds were chemically treated. The fabricated composite specimens are tested under tensile load using Universal Testing Machine (UTM) in accordance with the ASTM D-638 standard. Then, a comparison of the experimental results against analytical results is made to examine the accuracy and agreement between the two. An inconsistency in moduli, as was discovered, is attributed to the adhesion quality between the fibers and surrounding matrix. Output results help to assess the applicability of such class of bio-composites in real-life applications. The results of tensile strength, Young's modulus, and elongation at break revealed that date palm fronds can be used as reinforcement material in polymer-based composites for low strength applications. Keywords

The objective of this study was to investigate the effects on operator performance and satisfaction of an ergonomically designed workstation for performing a repetitive industrial assembly task. Experiments were conducted in a company with industrial workers using existing and newly developed workstations. Operator performance on the ergonomically designed workstation was 27% higher compared to the existing non-ergonomically designed workstation. Worker satisfaction score was also improved by 41% in the ergonomically designed workstation condition. The new workstation for a repetitive assembly task had highly significant positive effect on worker performance and satisfaction. Special features of the ergonomically designed assembly workstation were an adjustable and adequate worktable, an adjustable and ergonomically designed chair, ergonomically designed hand tools and a systematic layout of the workstation components.

<p>The rocks of the Saih Hatat Dome (SHD) formed during and after two major geological events shaping Arabia: 1) Subduction of continental rocks in the course of the Late Cretaceous Semail Ophiolite obduction onto the Arabian Plate and 2) Exhumation of >16 km and high deformation/folding in the northeastern part of the SHD. The latter resulted in a ~20 km wide recumbent fold (Saih Hatat Fold Nappe). The sub-horizontal fold axis of this fold trends NNE in the northern SHD. The core of the SHD and the recumbent fold consist of dark Neoproterozoic meta-shales and meta-sandstones, while its margin (and upper/lower limbs of the recumbent fold) consist of Permian cliff-forming carbonates.</p><p>Within the northern SHD, numerous milky quartz veins occur. We structurally and mineralogical analyzed >500 of these veins, covering an area of ~200 km<sup>2</sup>. The veins vary in width from one centimeter to a few meters, while the length ranges between several decimeters to several decameters. Associated with the predominant milky quartz, are calcite, siderite, chlorite, albite, anorthite, actinolite, rutile, hematite, goethite, and pyrrhotite. Rare molybdenite aggregates seem to replace carbonate, in which it occurs exclusively. Quartz microstructures include bulging (BLG) recrystallization, sub-grain rotation (SGR) recrystallization, and undulose extinction. Sub-grains and triple junctions in quartz are common. The mineralogy and quartz microstructures indicate maximum peak temperature conditions of ~400-500°C.</p><p>At least two sets of veins can be distinguished. Both vein sets occur mostly in clusters and partly form vein swarms. The mineralogy and quartz microstructure of both vein sets is similar. The older set 1 has been folded by the Saih Hatat Fold Nappe. Thus, vein formation predates 76-70 Ma. Furthermore, veins of set 1 are often sub-parallelly oriented to the main foliation of the host rocks, and they may be boudinaged. They may form complicated vein structures. We assume that this vein set initially formed during the Permian Pangean/Tethys rifting. The second vein set is abundant, sub-vertically and strikes consistently E/W to ESE/WNW. These veins cut the overall moderately NW-dipping bedding surfaces of the ambient rocks. Set 2 veins either formed during exhumation of the dome (Late Cretaceous to early Eocene and late Eocene to Oligocene) or they are part of the NW-striking sinistral Hajar Shear Zone, which affected the entire eastern Oman Mountains during the Oligocene to early Miocene. Ongoing U-Pb dating of carbonates and further field survey will further contribute to the understanding of their age and tectonic setting.</p>