19672 research outputs found
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Multi-Wavelength Q-Switched Ytterbium-Doped Fiber Laser with Multi-Walled Carbon Nanotubes
No full textWe demonstrate a passively multi-wavelength Q-switched Ytterbium-doped fiber laser (YDFL) based on a multi-wall carbon nanotubes embedded in polyethylene oxide film as saturable absorber. The YDFL generates a stable multi-wavelength with spacing of 1.9 nm as the 980 nm pump power is fixed within 62. 4 mW and 78.0 mW. The repetition rate of the laser is tunable from 10.41 to 29.04 kHz by increasing the pump power from the threshold power of 62.4 mW to 78 mW. At 78 mW pump power, the maximum pulse energy of 38 nJ and the shortest pulse width of 8.87 µs are obtained
Synchronizing Artificial Intelligence Models for Operating the Dam and Reservoir System
No full textIt is remarkable that several hydrological parameters have a significant effect on the reservoir operation. Therefore, operating the reservoir system is complex issue due to existing the nonlinearity hydrological variables. Hence, determining modern model has high ability in handling reservoir operation is crucial. The present study developed artificial intelligence model, called Shark Machine Learning Algorithm (SMLA) to provide optimal operational rules. The major objective for the proposed model is minimizing the deficit volume between water releases and the irrigation water demand. The current study compared the performance of the SML model with popular evolutionary computing methods, namely Particle Swarm Optimization (PSO) and Genetic Algorithm (GA). The proposed models have been utilized of finding the optimal policies to operate Timah Tasoh Dam, which is located in Malaysia. The study utilized considerable statistical indicators to explore the efficiency of the models. The simulation period showed that SMLA approach outperforms both of conventional algorithms. The SMLA attained high Reliability and Resilience (Rel. = 0.98%, Res. = 50%) and minimum Vulnerability (Vul. = 21.9 of demand). It is demonstrated that shark machine learning algorithm would be a promising tool in handling the long-term optimization problem in operation a reservoir system
Primary conjunctiva tuberculosis & review of literature
No full textThe causes of chronic conjunctivitis are exhaustive, infection being the commonest. Primary tuberculosis(TB) involving the conjunctiva is rare. History of chronicity, worsening symptoms with steroids and clinical signs of subconjunctiva nodules could point towards the diagnosis of primary conjunctiva tuberculosis especially in endemic countries. Clinicopathological diagnosis is imperative to confirm this diagnosis. We report a case of a young lady who presented with a non-resolving chronic conjunctivitis that was proven to be TB and responded well to anti-tuberculosis treatment
Evaluation of production cross-sections for 61Cu non-standard PET radionuclide via light-ion-induced nuclear reactions on Co, Ni, Zn targets
No full textProduction cross-sections of 61Cu, a promising radionuclide for PET imaging applications, were evaluated for the light-ion-induced nuclear reactions on Co, Ni, Zn targets. Simultaneous Evaluation on KALMAN (SOK) code combined with least squares concept was used to obtain the evaluated data together with covariances. The various production routes of 61Cu were compared, and recommended excitation functions were derived using a well-defined statistical procedure. The evaluated data were also compared with the predictions of the nuclear reaction model codes TALYS and EMPIRE, and found a partial agreement among them. This study indicates that the 60Ni(d,n)61Cu reaction is the method of choice for 61Cu production; however, the 58Ni(α,p)61Cu and 59Co(α,2n)61Cu reactions also appears to have great potential
Synthesis and characterisation of floatable magnesium alloy syntactic foams with hybridised cell morphology
No full textPowder metallurgy and rapid microwave (MW) sintering techniques were successfully applied to engineer a hybrid cell structure into magnesium alloy AZ61 syntactic foams. The hybrid cell structure, comprising open- and closed-cells, originated from leached carbamide granules and hollow microspheres of fly ash (HS), respectively. External MW susceptors accelerated the sintering process and greatly mitigated the formation of undesirable interfacial reactions. The cell hybridisation technique facilitated control over the density and strength of the syntactic foams. Accordingly, floatable syntactic foams with a density of about 0.79 g/cm3 and compressive strength of 16 MPa were synthesised without recourse to any surface modification or chemically-induced superhydrophobicity. The processing techniques were capable of mitigating damage to the HS microspheres as confirmed by microstructural examinations. Furthermore, potential applications of the floatable syntactic foam sample, as a microboat and chemical release agent, were demonstrated by using ethanol as a propellant. AZ61 syntactic foams synthesised in this study exhibited low density and adequate strength, suggesting their applicability as alternative materials to polymer composite foams
Roles of leadership styles and relationship-based employee governance in open service innovation
No full textPurpose: The purpose of this paper is to investigate the relationship of leadership styles (paternalistic, authentic and democratic) with relationship-based employee governance and open service innovation. Design/methodology/approach: Data were collected using a structured questionnaire from 422 medical professionals working in the Malaysian healthcare sector. Findings: Results of several statistical analyses showed that the three leadership styles positively influence relationship-based employee governance and open service innovation. Results also confirmed the mediating role of relationship-based employee governance in the relationships between the three leadership styles and open service innovation. Research limitations/implications: This research used a cross-sectional study design; use of a longitudinal research design in future research can provide a better interpretation of the underlying causality. A policy insight can be drawn from this research to generate awareness about effective leadership styles and the role of relationship-based employee governance in the successful implementation of open service innovation in the Malaysian healthcare sector. Originality/value: This paper contributes to leadership, open innovation, and organizational governance literature by highlighting how leadership styles affect relationship-based employee governance and open innovation. It also offers policy insights to practitioners in the Malaysian healthcare sector on how to enhance open service innovation outcomes
Planar hybrid carbon-decorated zinc oxide nanowires for infrared photodetection
No full textVapor phase transport (VPT) assisted by thermal evaporation of methanol was utilized to favor the fabrication of hybrid carbon-decorated zinc oxide nanowires (C/ZnO NWs). The photoluminescence (PL) spectrum revealed evidence of optical properties for several defects such as zinc interstitials (Zni) and oxygen vacancy (Vo) in hybrid C/ZnO NWs. The PL also exhibited that the planar hybrid C/ZnO NWs photodetector has a wide range of sensitivity from ultraviolet (UV) to infrared (IR). The imaging results show formation of ZnO nanostructures which can be further confirmed from X-ray diffraction (XRD) results. XRD exhibits carbon (C)-related peaks at 12.88, 26, 43, 45, and 55° together with standard ZnO peaks. The incorporation of C shows excellent photoconduction towards varied laser powers (0.0, 7.82, 37.95, 69.20, 100.0, 130.0, and 160.0 mW) of IR illumination. The possibility of current drain in the device was evaluated based on the direct-current (DC) bias voltage of 0.00, 3.33, and 5.55 V. DC bias 3.33 and 5.55 V attributed increase of photocurrent towards the forward bias voltage. However, the reverse bias voltage illustrated a vast increase of photocurrent compared to the forward bias voltage. External quantum efficiency (EQE) at DC bias 5.55 V was 6.5–9.5 range folds greater than the EQE measured for zero bias voltage. Significant photoresponsivity was identical for various laser pulse ranging from 10 to 5000 Hz. Simultaneously, the rise (τr) and fall (τf) time were measured at 49 and 60.5 μs attributes that the fabrication technique can be improvised and implemented to enhance the efficiency of optoelectronic devices for future applications
Passively Q-switched erbium-doped fiber laser using coated reduced graphene oxide on arc-shaped single mode optical fiber as a saturable absorber
No full textA passively Q-switched erbium-doped fiber laser is demonstrated using saturable absorbers based on the evanescent light field interaction of reduced graphene oxide deposited on ground arc-shaped fiber. The Q-switched operation started at 32.42 mW with a lowest repetition rate of 34.48 kHz and a pulse width of 5.05 μs. A Q-switched pulse is obtained at different levels of pump power with corresponding repetition rates and pulse widths. From the obtained results, the repetition rate increases from 34.48 kHz to 54.10 kHz; in contrast, the pulse width decreases from 5.01 μs to 2.01 μs. The average output power and pulse energy are increased by enhancing pump power from 32.42 mW to 119.5 mW. Additionally, the fundamental frequency is maintained over time with the signal-to-noise ratio of ∼55 dB, thus indicating the Q-switched process is stable over a period of 90 min
Effects of equivalence ratio on performance and emissions of diesel engine with hydrogen and water injection system at variable injection timing
No full textThis paper aims to develop a comprehensive development and research for performance and emissions of diesel engine fueled with hydrogen and water at variable injection timing. Experiments have been conducted to compare the performance and emissions between diesel alone, diesel with hydrogen and hydrogen-diesel and water injection pressure. addition of hydrogen into diesel engine resulted in higher pressure which lead to huge indicated work. Furthermore, injecting water into diesel engine with hydrogen mixture indicated a desirable outcome. Existence of water in combustion slightly decreased the amount of emissions but opposite in term of performance. The fact is water injection exist in combustion will absorb a portion of heat release which will result low in combustion process thus lead to low in performance production otherwise production of NOx emission is low. In conclusion, humidification in combustion engine is a great idea toward a high performance and low in emissions production compared to diesel alone operation which leads to a green technology production
Assessment of groundwater salinity and quality in Gaza coastal aquifer, Gaza Strip, Palestine: An integrated statistical, geostatistical and hydrogeochemical approaches study
No full textA comprehensive study was conducted to identify the salinization origins and the major hydrogeochemical processes controlling the salinization and deterioration of the Gaza coastal aquifer system through a combination approaches of statistical and geostatistical techniques, and detailed hydrogeochemical assessments. These analyses were applied on ten physicochemical variables for 219 wells using STATA/SE12 and Surfer softwares. Geostatistical analysis of the groundwater salinity showed that seawater intrusion along the coastline, and saltwater up-coning inland highly influenced the groundwater salinity of the study area. The hierarchical cluster analysis (HCA) technique yielded seven distinct hydrogeochemical signature clusters; (C1&C2: Eocene brackish water invasion, C3 saltwater up-coning, C4 human inputs, C5 seawater intrusion, C6 & C7 rainfall and mixing inputs). Box plot shows a wide variation of most of the ions while Chadha's plot elucidates the predominance of Na-Cl (71.6%) and Ca/Mg-Cl (25%) water types. It is found that, the highest and the lowest levels of salinization and the highest level of nitrate pollution were recorded in the northern area. This result reflects the sensitivity of this area to the human activities and/or natural actions. Around 90.4% of the wells are nitrate polluted. The main source of nitrate pollution is the sewage inputs while the farming inputs are very limited and restricted mostly in the sensitive northern area. Among the hydrogeochemical processes, ion exchange process was the most effective process all over the study area. Carbonate dissolution was common in the study area with the highest level in clusters 6, 7, 4 and 2 in the north while Gypsum dissolution was significant only in cluster 1 in the south and limited in the other clusters. This integrated multi-techniques research should be of benefit for effective utilization and management of the Gaza coastal aquifer system as well as for future work in other similar aquifers systems