5,647 research outputs found
An 80-year projection of nZEB strategies in extreme climatic conditions of Iraq
Purpose – The Middle Eastern terrain is expected to encounter unprecedented climatic conditions before the turn of the next century (circa. 80 years), emanating from extreme heat waves that exceed the critical threshold of habitable conditions. This threatens to cause a significant challenge that is exacerbated by a gap between the supply and demand of affordable energy. Therefore, the purpose of this study is to investigate the potential of utilising nearly zero-energy buildings (nZEB) to improve the performance of residential buildings in Iraq and the Middle East.Design/methodology/approach – This study uses Iraq as a case-study because of the breadth of climatic conditions experienced across its wide-reaching territory and also because of the recent critical infrastructural challenges following the geo-political crisis. Three virtual buildings were simulated for Baghdad, Mosul and Basra cities to narrow the confines of the region to achieve nZEB under current and future climatic weather scenarios.Findings – The findings showed that in all three cases studies, the buildings located within the three climatic regions in Iraq could achieve both significant annual energy reductions as well as nZEB standards which could range from 41 per cent to 87 per cent for current climatic conditions and 40 per cent to 84 per cent by 2080. An analysis has also been carried out for the three case-study cities which revealed significant operational-cost savings achievable through nZEB buildings.Originality/value – There are currently limited studies that investigate such positive potential for nZEB strategies under the current and predicted future climatic scenarios in the Middle East.<br/
Learning organization practices and their relationship with organizational performance moderated by background variables in Yemeni Telecommunication Organizations / Ghamdan Yahya Abdullah Al-Odhari
This study aims to explore learning organization practices and their relationship with organizational performance in Yemeni Telecommunication Organizations (YTOs). A survey approach using a version of Arabic translated Dimensions of the Learning Organization Questionnaire (DLOQ) developed by Watkins and Marsick (1993) that implies seven characteristics to the development of a learning organization, namely, continuous learning, inquiry and dialogue, teamwork, embedded systems, empowerment, systems connections, and provision of leadership are used. Five communication organizations were participated in this study (3 local: Public Yemeni Telecommunication, TeleYemen, and Yemen Mobile; and 2 Foreign: SabaFon and MTN). A total of 577 questionnaires were distributed, to employees at both senior and middle levels, and 447 questionnaires were returned with a response rate of 77.5%. Results of the study revealed that the practices of the seven dimensions showed low especially empowerment, while the highest dimension was continuous learning. Correlation analysis showed that all of the correlation coefficients were significant at the .01 level, and with an overall medium positive relationship with financial performance while large with knowledge performance
Enhancing Clinical Learning Through an Innovative Instructor Application for ECMO Patient Simulators
© 2018 The Authors. Reprinted by permission of SAGE PublicationsBackground. Simulation-based learning (SBL) employs the synergy between technology and people to immerse learners in highly-realistic situations in order to achieve quality clinical education. Due to the ever-increasing popularity of extracorporeal membrane oxygenation (ECMO) SBL, there is a pressing need for a proper technological infrastructure that enables high-fidelity simulation to better train ECMO specialists to deal with related emergencies. In this article, we tackle the control aspect of the infrastructure by presenting and evaluating an innovative cloud-based instructor, simulator controller, and simulation operations specialist application that enables real-time remote control of fullscale immersive ECMO simulation experiences for ECMO specialists as well as creating custom simulation scenarios for standardized training of individual healthcare professionals or clinical teams. Aim. This article evaluates the intuitiveness, responsiveness, and convenience of the ECMO instructor application as a viable ECMO simulator control interface. Method. A questionnaire-based usability study was conducted following institutional ethical approval. Nineteen ECMO practitioners were given a live demonstration of the instructor application in the context of an ECMO simulator demonstration during which they also had the opportunity to interact with it. Participants then filled in a questionnaire to evaluate the ECMO instructor application as per intuitiveness, responsiveness, and convenience. Results. The collected feedback data confirmed that the presented application has an intuitive, responsive, and convenient ECMO simulator control interface. Conclusion. The present study provided evidence signifying that the ECMO instructor application is a viable ECMO simulator control interface. Next steps will comprise a pilot study evaluating the educational efficacy of the instructor application in the clinical context with further technical enhancements as per participants’ feedback.Peer reviewedFinal Accepted Versio
Molybdenum (VI) imido complexes derived from chelating phenols : Synthesis, characterization and ɛ-Caprolactone ROP capability
Reaction of the bulky bi-phenols 2,2′-RCH[4,6-(t-Bu)₂C₆H₂OH]₂ (R = Me L¹ᵐᵉH₂, Ph L¹ᵖʰH₂) with the bis(imido) molybdenum(VI) tert-butoxides [Mo(NR¹)(NR²)(Ot-Bu)₂] (R¹ = R² = 2,6-C₆H₃-i-Pr₂; R¹ = t-Bu, R² = C₆F₅) afforded, following the successive removal of tert-butanol, the complexes [Mo(NC₆H₃ᵢ-Pr₂-2,6)₂L¹ᵐᵉ] (1), [Mo(NC₆H₃i-Pr₂-2,6)₂L¹ᵖʰ] (2) and [Mo(Nt-Bu)(μ-NC₆F₅)(L¹ᵐᵉ)]₂ (3). Similar use of the tri-phenol 2,6-bis(3,5-di-tert-butyl-2-hydroxybenzyl)-4-methylphenol (L²H₃) with [Mo(NC₆H₃ᵢ-Pr₂-2,6)₂(Ot-Bu)₂] afforded the oxo-bridged product [Mo(NC₆H₃i-Pr₂-2,6)(NCMe)(μ-O)L2H]₂ (4), whilst use of the tetra-phenols α,α,α′,α′-tetrakis(3,5-di-tert-butyl-2-hydroxyphenyl)-p- or -m-xylene L³ᵖH₄/L³ᵐH₄ led to {[Mo(NC₆H₃ᵢ-Pr₂-2,6)₂]₂(μ-L³ᵖ)} (5) or {[Mo(NC₆H₃ᵢ-Pr₂-2,6)₂]₂(μ-L³ᵐ)} (6), respectively. Similar use of [Mo(NC₆F₅)₂(Ot-Bu)₂] with L³ᵖH₄ afforded, after work-up, the complex {[Mo(NC₆F₅)(Ot-Bu)₂]₂(μ-L³ᵖ)}·6MeCN (7·6MeCN). Molecular structures of 1, 2·CH₂Cl₂, 3, 4·6MeCN, 6·2C₆H₁₄, and 7·6MeCN are reported and these complexes have been screened for their ability to ring open polymerize (ROP) ε-caprolactone; for comparative studies the precursor complex [Mo(NC₆H₃ᵢ-Pr₂-2,6)₂Cl₂(DME)] (DME = 1,2-dimethoxyethane) has also been screened. Results revealed that good activity is only achievable at temperatures of ≥100 °C over periods of 1 h or more. Polymer polydispersities were narrow, but observed molecular weights (Mn) were much lower than calculated values
Multimetallic lithium complexes derived from the acids Ph₂C(X)CO₂H (X = OH, NH₂) : synthesis, structure and ring opening polymerization of lactides and lactones
Reaction of LiOR (R=t-Bu, Ph) with the acids 2,2/-Ph₂C(X)(CO₂H), X=OH (benzH), NH₂ (dpgH) was investigated. For benzH, one equivalent LiOt-Bu in THF afforded [Li(benz)]2⋅2THF (1⋅2THF), which adopts a 1D chain structure. If acetonitrile is used (mild conditions), another polymorph of 1 is isolated; LiOPh also led to 1. Robust work-up afforded [Li₇(benz)₇(MeCN)] 2MeCN THF (2⋅2MeCN⋅THF). Use of LiOt-Bu (2 equivalents) led to {Li₈(Ot-Bu)₂[(benz)](OCPh₂CO₂CPh₂CO2t-Bu)₂(THF)₄} (3), the core of which comprises two open cubes linked by benz ligands. For dpgH, two equivalents of LiOt-Bu in THF afforded [Li6(Ot-Bu)₂(dpg)₂(THF)₂] (4), which contains an Li₂Ov 6-step ladder. Similar reaction of LiOPh afforded [Li₈(PhO)₄(dpg)₄(MeCN)₄] (5). Complexes 1–5 were screened for their potential as catalysts for ring opening polymerization (ROP) of ϵ-caprolactone (ϵ-CL), rac-lactide (rac-LA) and δ-valerolactone (δ-VL). For ROP of ϵ-CL, conversions > 70 % were achievable at 110 °C with good control. For rac-LA and δ-VL, temperatures of at least 110 °C over 12 h were necessary for activity (conversions > 60 %). Systems employing 2 were inactiv
Organoaluminium complexes derived from Anilines or Schiff bases for ring opening polymerization of epsilon-caprolactone, delta-valerolactone and rac-lactide
Reaction of R¹R²CHN=CH(3,5-tBu₂C₆H₂-OH-2) (R¹ = R² = Me L¹H; R¹ = Me, R² = Ph L²H; R¹ = R2 = Ph L³H) with one equivalent of R³3Al (R³ = Me, Et) afforded [(L¹-³)AlR³₂] (L¹, R³ = Me 1, R³ = Et 2; L², R³ = Me 3, R³ = Et 4; L³ R³ = Me 5, R³ = Et 6); complex 1 has been previously reported. Use of the N,O-ligand derived from 2,2/-diphenylglycine afforded either 5 or a by-product [Ph₂NCH₂(3,5-tBu₂C₆H₂-O-2)AlMe₂] (7). The known Schiff base complex [2-Ph₂PC₆H4CH₂(3,5-tBu₂C₃H₂-O-2)AlMe₂] (8) and the product of the reaction of 2-diphenylphosphinoaniline 1-NH₂,2-PPh₂C₆H4 with Me3Al, namely {Ph₂PC₆H4N[(Me₂Al)₂mu-Me](mu-Me₂Al)} (9) were also isolated. For structural and catalytic comparisons, complexes resulting from interaction of Me₃Al with diphenylamine or benzhydrylamine, namely {Ph₂N[(Me₂Al)2mu-Me]} (10) and [Ph₂CHNH(mu-Me₂Al)]₂·MeCN (11), were prepared. The molecular structures of the Schiff pro-ligands derived from Ph₂CHNH₂ and 2,2/-Ph2C(CO₂H)(NH₂), together with complexes 5, 7 and 9 - 11·MeCN were determined. All complexes have been screened for their ability to ring opening polymerization (ROP) epsilon-caprolactone, delta-valerolactone or rac-lactide, in the presence of benzyl alcohol, with or without solvent present. The co-polymerization of epsilon-caprolactone with rac-lactide has also been studied
Distributed Adaptive Algorithms for Optimal Opportunistic Medium Access
We examine threshold-based transmission strategies for distributed opportunistic medium access in a scenario with fairly general probabilistic interference conditions. Specifically, collisions between concurrent transmissions are governed by arbitrary probabilities, allowing for a form of channel capture and covering binary interference constraints as an important special case. We address the problem of setting the threshold values so as to optimize the aggregate throughput utility of the various users, and particularly focus on a weighted logarithmic throughput utility function (Proportional Fairness). We provide an adaptive algorithm for finding the optimal threshold values in a distributed fashion, and rigorously establish the convergence of the proposed algorithm under mild statistical assumptions. Moreover, we discuss how the algorithm may be adapted to achieve packet-level stability with only limited exchange of queue length information among the various users. We also conduct extensive numerical experiments to corroborate the theoretical convergence results.14 page(s
Evaluating Design Strategies for Nearly Zero Energy Buildings in the Middle East and North Africa Regions
There is international pressure for countries to reduce greenhouse gas emissions, which are blamed as the main cause of climate change. The countries in the Middle East and North Africa (MENA) region heavily rely on fossil fuel as the main energy source for buildings. The concept of nearly zero energy buildings (nZEB) has been defined and standardized for some developed countries. While most of the developing countries located in the MENA region with hot and tropical climate lack building energy efficiency standards. With pressure to improve energy and environmental performance of buildings, nZEB buildings are expected to grow over the coming years and employing these buildings in the MENA region can reduce building energy consumption and CO2 emissions. Therefore, the paper focuses on: (a) reviewing the current established nZEB standards and definitions for countries in the hot and warm climate of Europe, (b) investigate the primary energy consumption for current existing buildings in the MENA region, and (c) establishing a standard for nZEB and positive energy buildings in kWh/m2/year for the MENA region using a building simulation platform represented using Autodesk Insight 360. The result of the simulation reveals high energy use intensity for existing buildings in the MENA region. By improving building fabric and applying solar photovoltaics (PV) in the base model, significant reductions in primary energy consumption was achieved. Further design improvements, such as increasing the airtightness and using high efficiency solar PV, also contributed to positive energy buildings that produce more energy than they consume
Impact of mobility on the IoT MAC infrastructure: IEEE 802.15.4e TSCH and LLDN platform
Realizing the target of high reliability and availability is a crucial concept in the IoT context. Different types of IoT applications introduce several requirements and obstacles. One of the important aspects degrading network performance is the node mobility inside the network. Without a solid and adaptive mechanism, node mobility can disrupt the network performance due to dissociations from the network. Hence, reliable techniques must be incorporated to tackle the overhead of node movement. In this paper, the overhead of mobility on both IEEE 802.15.4e timeslotted channel hopping (TSCH) and low latency deterministic (LLDN) modes is investigated. These two modes can be considered as the MAC layer of the IoT paradigm because of their importance and resilience to different network obstacles. In addition, the set of metrics and limitations that influence the network survivability will be identified to ensure efficient mobile node handling process. Both TSCH and LLDN have been implemented via the Contiki OS to determine their functionality. TSCH has been demonstrated to have better node connectivity due to the impact of frame collision in LLDN. In addition, by neglecting the overhead of collision, the LLDN has been shown to have better connectivity and low radio duty cycle (RDC)
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