A Generalised Approach for the Prediction of Laser Cutting Parameters

A design of a tasking and control environment for laser based manufacturing systems is proposed. This uses an empirical approach based on recording previous manufacturing experience in a database, in order that this can be used in planning and control of future processes. The work presented gives details of the partial implementation of this design for laser cutting systems. This makes use of Computer Aided Design and Manufacture, Computer Numerical Controlled laser cutting machines, database and computerised planning and control

Environmental determinants of the ecology and distribution of Acacia tortilis under arid conditions in Qatar

PhD ThesisScrub or woodland communities dominated by Acacia tortilis form one of the few tree-dominated natural ecosystems in the hyper-arid climate of Qatar, making it a very important tree species that provides an essential habitat both for native animals and domestic livestock. However, the conservation and sustainable management of this tree has so far been neglected and it is now severely impacted by overgrazing and wood fuel collection. This research investigates the main environmental, ecological and management factors affecting the growth and distribution of Acacia tortilis in Qatar, including the factors affecting its regeneration. It also aims to guide the implementation of conservation programmes and development of a strategy to forestall deforestation and prevent the extinction of Acacia tortilis in Qatar. Initially, field survey, remote sensing and GIS techniques, together with univariate and multivariate statistical modelling techniques, were used to explore environmental influences on distribution of A. tortilis in Qatar at a national scale. Different vegetation indices (VIs), normalized difference vegetation index (NDVI), soil adjusted vegetation index (SAVI), were derived for a time series of Landsat TM/ETM+ images for 1998 and 2010 and tested using ground-truth data to explore the temporal dynamics of Acacia-dominated ecosystems which indicated substantial reduction in vegetation greenness in 2010 than 1998. The initial approach had limited success due to difficulties of identifying Acacia tortilis communities accurately on satellite images due to the sparsity of tree cover and indicates the limitations of using remote sensing methods for tracing vegetation dynamics in Qatar and similar arid and hyper arid environments. The multinomial logistic regression model has a superior ability to predict Acacia distribution and is a suitable method in the prediction of the occurrence of different vegetation types. Phytogeographical investigations of the environmental and biotic factors that control the distribution of the Acacia tortilis at a local scale, in both areas protected and unprotected from human land use impacts, demonstrate that topographic factors and their control on soil and water conditions are fundamental determinants. The distinctive topography of Qatar has resulted in a heterogeneous soil landscape with extreme contrasts of chemical and physical soil conditions within and between depressions and more elevated positions in soil toposequences. Depressional land forms are more suitable for the Acacia tree growth than the surrounding higher ground because ENVIRONMENTAL DETERMINANTS OF ACACIA TORTILIS IN QATAR II depression soils have greater soil water content, soil depth, organic carbon and available phosphorus contents. Conversely, the absence of Acacia trees in summit areas is related to severe limitations for tree growth, including negligible soil water content and shallow soil depth caused by impeding bedrock or cemented horizons resulting in drought stress, as well as large contents of gypsum and/or CaCO3 in soils. The slope-controlled movement of eroded soil material, water and plant debris, and the localised leaching of soluble salts, are suggested to be important processes that lead to improved soil quality and better tree growth in depressions. The regeneration of Acacia tortilis through seedling establishment is perhaps surprisingly shown to be greater in the unprotected than in protected areas. This is attributed to the importance of ingestion by large mammals (mainly domestic herbivores) on the germination and recruitment of Acacia seedlings. The greater frequency of Acacia saplings in depressions within the unprotected areas is, however, also attributed to the presence of greater amounts of soil water, soil depth, available phosphorus, and organic carbon. Although the action of browsing may be regarded as positive, most anthropogenic impacts were shown to have negative effects on the condition and distribution of Acacia tortilis. The results proved that the impacts of cutting and browsing were severe in the unprotected sites, despite the evidence of more active regeneration. It is concluded that there is an urgent need to review the provision and management of protected habitats for Acacia tortilis in Qatar. It is suggested that cutting for domestic use should be restricted; that conservation efforts should be concentrated in depressions that favour tree growth; and that the livestock numbers should be limited to enable seedling establishment without excessive browsing.“Qatar University”, for sponsoring my Ph.D. researc

An Ant Colony Algorithm for HRES Size and Configuration Optimisation

Postprin

Business process modeling for software acquisition - A literature review

Los Alamitos, US

Comparative Study between using of Biomass and Extract of Trichoderma Viride to Inducing Anticancer (TIA) Vincristine Production from Catharanthus Roseus in Vitro

This experiment was conducted in college of Agriculture , Al-Qasem Green university in 2015 ,to study the different of effects between using Trichoderma viride as biomass and as extract to induce the production of anticancer vincristine in vitro  using MS medium supplemente with (2,4-D) and (BA) in (1+1) mg /L concentration to induce callus  production then inoculated the callus directly with biomass of T.viride by single spore .In first method and adding extract of T.viride to the MS medium in the second method .The study include quantity and quality determination of vincristine by HPLC technique .Results revealed that the highest values was for the using of T.viride as biomass which gave(25.120)µg/g vincristine and the lowest value was for T.viride as extract which gave(15.346)µg/g vincristine .also results explained that adding of T.viride as biomass and the extract cause decrease in the fresh and dry weight of callus inducing from leaves of C.roseus and the highest decrease was to biomass method (200, 0.019) mg followed by  extractmethod(340,0.031)mgrespectively. Keywords: Trichoderma viride in vitro, vincristine extract

Dispatch Strategy as a Design Variable in Hybrid Renewable Energy System Optimisation

Postprin

Thermal-Hydraulic performance in a microchannel heat sink equipped with longitudinal vortex generators (LVGs) and nanofluid

In this study, the numerical conjugate heat transfer and hydraulic performance of nanofluids flow in a rectangular microchannel heat sink (RMCHS) with longitudinal vortex generators (LVGs) was investigated at different Reynolds numbers (200-1200). Three-dimensional simulations are performed on a microchannel heated by a constant temperature with five different configurations with different angles of attack for the LVGs under laminar flow conditions. The study uses five different nanofluid combinations of Al2O3 or CuO, containing low volume fractions in the range of 0.5% to 3.0% with various nanoparticle sizes that are dispersed in pure water, PAO (Polyalphaolefin) or ethylene glycol. The results show that for Reynolds number ranging from 100 to 1100, Al2O3-water has the best performance compared with CuO nanofluid with Nusselt number values between 7.67 and 14.7, with an associated increase in Fanning friction factor by values of 0.0219-0.095. For the case of different base fluids, the results show that CuO-PAO has the best performance with Nusselt number values between 9.57 and 15.88, with an associated increase in Fanning friction factor by 0.022-0.096. The overall performance of all configurations of microchannels equipped with LVGs and nanofluid showed higher values than the ones without LVG and water as a working fluid. © 2020 by the authors

Climate Zones of the Asphalt Binder Performance for the Highway Pavement Design

The asphalt pavement is exposed to the natural environment, which is affected by Climate change such as temperature, rain, ultraviolet, and other environmental conditions. This study aimed to establish the asphalt binder performance of Yemen so that the asphalt pavement can be designed to resist the distresses of rutting and cracking that occurred due to seasonal temperature changes and rainfall. The first step of determining the binder performance is to establish high and low temperatures, as well as rainfall because the asphalt binder is a temperature and rainfall sensitive viscoelastic material. To study the climatic zoning of asphalt pavement in Yemen, the data of temperature and rainfall in 19 provinces of Yemen in the past 10 years were collected and comprehensively analyzed, and the variations laws of them were analyzed. According to the Chinese approach, the climatic zoning of Yemen's asphalt pavement was divided. The moisture temperature coefficient was introduced, and its probability distribution state was also analyzed. The standard of the moisture temperature coefficient was suggested and the asphalt pavement climate zones based on the moisture temperature coefficient were determined. The results indicated that the main influencing factors of asphalt pavement in Yemen were the temperature rise and rainfall, and the climate zones of asphalt pavement were divided into different zones such as 1-2-1, 2-2-2, 1-2-2, and 3-1-2. According to the principle of equal probability, the moisture temperature coefficient was found to be 18, and the asphalt pavement climate zoning map was drawn. The findings of this study are highly significant and provide valuable decision support for pavement management and improve the transportation system. Doi: 10.28991/cej-2020-03091613 Full Text: PD

Human Body Posture Recognition Approaches: A Review

Human body posture recognition has become the focus of many researchers in recent years. Recognition of body posture is used in various applications, including surveillance, security, and health monitoring. However, these systems that determine the body’s posture through video clips, images, or data from sensors have many challenges when used in the real world. This paper provides an important review of how most essential ‎ hardware technologies are ‎used in posture recognition systems‎. These systems capture and collect datasets through ‎accelerometer sensors or computer vision. In addition, this paper presents a comparison ‎study with state-of-the-art in terms of accuracy. We also present the advantages and ‎limitations of each system and suggest promising future ideas that can increase the ‎efficiency of the existing posture recognition system. Finally, the most common datasets ‎applied in these systems are described in detail. It aims to be a resource to help choose one of the methods in recognizing the posture of the human body and the techniques that suit each method. It analyzes more than 80 papers between 2015 and 202