Nature-inspired Cuckoo Search Algorithm for Side Lobe Suppression in a Symmetric Linear Antenna Array

In this paper, we proposed a newly modified cuckoo search (MCS) algorithm integrated with the Roulette wheel selection operator and the inertia weight controlling the search ability towards synthesizing symmetric linear array geometry with minimum side lobe level (SLL) and/or nulls control. The basic cuckoo search (CS) algorithm is primarily based on the natural obligate brood parasitic behavior of some cuckoo species in combination with the Levy flight behavior of some birds and fruit flies. The CS metaheuristic approach is straightforward and capable of solving effectively general N-dimensional, linear and nonlinear optimization problems. The array geometry synthesis is first formulated as an optimization problem with the goal of SLL suppression and/or null prescribed placement in certain directions, and then solved by the newly MCS algorithm for the optimum element or isotropic radiator locations in the azimuth-plane or xy-plane. The study also focuses on the four internal parameters of MCS algorithm specifically on their implicit effects in the array synthesis. The optimal inter-element spacing solutions obtained by the MCS-optimizer are validated through comparisons with the standard CS-optimizer and the conventional array within the uniform and the Dolph-Chebyshev envelope patterns using MATLABTM. Finally, we also compared the fine-tuned MCS algorithm with two popular evolutionary algorithm (EA) techniques include particle swarm optimization (PSO) and genetic algorithms (GA)

Exploring motivational design and motivation types facilitated by an online support system for learning literature

This paper is a study designed to explore the influence of an Online Support System for learning Literature (LitOSS) on a group of twenty-five Form 4 Malaysian students who generally perceived English Literature as difficult and uninteresting. This asynchronous mode of learning was introduced with the intention of enhancing the students‟ motivation to learn English literature through a blended learning environment. LitOSS featured seven literature topics encompassing poems, short stories and novel, presented in the forms of online text-based materials, graphics and videos. This study was framed by the Social Cognitive Theory (SCT) of language learning, Keller‟s (1987) Attention, Relevance, Confidence and Satisfaction (ARCS) Model and the Social Cognitive Model of Motivation (SCMM). The motivational design of the system and the prevalent types of motivation facilitated by the system were measured using two sets of questionnaires (i.e. the adapted versions of WebMac Sr. 4.0 and Motivated Strategies for Learning Questionnaire (MSLQ)) and a focus group interview. Findings from the study support the prediction that LitOSS would significantly enhance students‟ motivation to learn literature due to its highly motivating design. It was also discovered that not only did the system promote self-efficacy and a high control of learning, it also motivated the students extrinsically and intrinsically

Standards for Tourism Management Success: U.S. National Park Managers

National park managers are the subjects in the fifth segment of a study examining the skills and abilities needed to be successful tourism managers. The authors discuss these skills and their impact on successful tourism management

A Numerical Study of Brace-Viscous Damper System of Fixed Offshore Jacket Platforms Under Extreme Environmental Loads

The Persian Gulf is one of the most common regions where offshore platforms exist due to the presence of oil and natural gas. Wind, current, and wave loading affect the dynamic response of offshore structures, increasing performance uncertainty and catastrophic failure probability. Thus, this study investigates energy dissipation systems, particularly viscous dampers, to solve design and rehabilitation problems of fixed offshore structures. Viscos dampers improve vibrational behaviour and reduce structural response to optimise platform performance. Thus, eliminating costly structural repairs and strengthening components under extreme environmental loads extends structure lifetime. Thus, different viscous damper system configurations are tested to reduce dynamic response under extreme environmental loads in the Persian Gulf. Diagonal and inverted V-shaped brace viscous dampers with nine different arrangements are compared to find the best configuration. The study found that the brace viscous dampers with only three applied dampers at the top three levels are most efficient at mitigating dynamic response. It reduced displacements from level 1 to level 5 by 52% to 64% and connection stresses by 38% to 54%. Finally, viscous dampers reduce structural vibration and provide uniform and constant structural dynamic response, so the oil and gas industry should use them for offshore structure design and rehabilitation

A Numerical Study of Brace-Viscous Damper System of Fixed Offshore Jacket Platforms Under Extreme Environmental Loads

The Persian Gulf is one of the most common regions where offshore platforms exist due to the presence of oil and natural gas. Wind, current, and wave loading affect the dynamic response of offshore structures, increasing performance uncertainty and catastrophic failure probability. Thus, this study investigates energy dissipation systems, particularly viscous dampers, to solve design and rehabilitation problems of fixed offshore structures. Viscos dampers improve vibrational behaviour and reduce structural response to optimise platform performance. Thus, eliminating costly structural repairs and strengthening components under extreme environmental loads extends structure lifetime. Thus, different viscous damper system configurations are tested to reduce dynamic response under extreme environmental loads in the Persian Gulf. Diagonal and inverted V-shaped brace viscous dampers with nine different arrangements are compared to find the best configuration. The study found that the brace viscous dampers with only three applied dampers at the top three levels are most efficient at mitigating dynamic response. It reduced displacements from level 1 to level 5 by 52% to 64% and connection stresses by 38% to 54%. Finally, viscous dampers reduce structural vibration and provide uniform and constant structural dynamic response, so the oil and gas industry should use them for offshore structure design and rehabilitation

External lightning protection system for wind turbine blades - aerodynamics.

Many wind turbine blade manufacturers have installed lightning protection systems (particularly the down conductor) internally. Having the down conductor internally within the blades would indeed preserve their aerodynamic performance. However, the blades are, as a consequence, vulnerable to damage and burn resulting from lightning strikes. Owing to this, the authors believe that by having the down conductor on the external surface of the blade, the incidence of blade damage would be reduced. The authors have not found any literature in the public domain that quantifies the effect of having an external down conductor on the aerodynamic performance. Hence, in this paper, a study of the effects of an externally mounted lightning conductor has been undertaken. Simulation studies were carried out using the computational fluid dynamics numerical method available in the COMSOL Multiphysics software package. The results of studies on single conductor arrangement have shown that the degradation on aerodynamic performance is least at the trailing edges of the blade. However, it may not be adequate for lightning protection. Therefore, using a similar numerical modelling methodology, simulations were extended and investigated on multiple conductor arrangements where conductors? locations were varied on an aerofoil surfaces. The results of the aerodynamic modelling suggested that a four conductor arrangement may be the best option as it gives more coverage for lightning protection of the wind turbine blades while still having the least reduction (of around 25%) on lift to drag ratio

Tourism Professionals Profile: Theme Park Managers

Theme park managers are a unique group of tourism managers. Their perspectives on effective tourism management skills and abilities differ from some public sector tourism managers. The authors present the results of a study focusing on theme park managers and compare these results with those of other tourism manager group

ERG-associated protein with SET domain (ESET)-Oct4 interaction regulates pluripotency and represses the trophectoderm lineage.

BACKGROUND: Pluripotency, the capacity for indefinite self-renewal and differentiation into diverse cell types is a unique state exhibited by embryonic stem (ES) cells. Transcriptional regulators, such as Oct4, are critical for pluripotency, but the role of epigenetic modifiers remains to be fully elucidated. RESULTS: Here, we show that ERG-associated protein with SET domain (ESET), a histone methyltransferase enzyme, maintains pluripotency through repression of Cdx2, a key trophectoderm determinant, by histone H3 lysine 9 trimethylation (H3K9me3) of the promoter region. Notably, this repression is mediated through the synergistic function of small ubiquitin-related modifier (SUMO)ylated ESET and Oct4. ESET localises to the promyelocytic leukaemia (PML) nuclear bodies and is SUMOylated in ES cells. Interaction of ESET with Oct4 depends on a SUMO-interacting motif (SIM) in Oct4, which is critical for the repression of Cdx2. CONCLUSION: Loss of ESET or Oct4 results in strikingly similar phenotypes both in ES cells with their differentiation into trophectoderm cells, and in early embryos where there is a failure of development of the pluripotent inner cell mass (ICM) of blastocysts. We propose that SUMOylated ESET-Oct4 complex is critical for both the initiation and maintenance of pluripotency through repression of differentiation, particularly of the trophectoderm lineage by epigenetic silencing of Cdx2.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are