bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of oxygen flow rate on physical properties of Al-doped ZnO transparent conducting films prepared by reactive dc magnetron sputtering using metallic Zn:Al target
Authors: Gaewdang T , Wongchaoen Ng 
Published: April 2020

Abstract
In this work, Al-doped ZnO transparent conducting thin films were prepared by a reactive dc magnetron sputtering method on slide glass substrate using single metallic Zn:Al (2 wt.% Al) target with the oxygen flow rate 1, 3, 5, 7 and 9 sccm, respectively. From XRD patterns, the films prepared at R(O2) of 1 sccm showed amorphous characteristics. In contrast, the films prepared at R(O2) of 3, 5, 7 and 9 sccm showed the preferred orientation (002) plane of hexagonal structure. Surface morphology and diameter of nanocolumns of the films were observed by AFM and FESEM. From transmittance spectra, energy gap value was found to vary between 3.24 and 3.32 eV. Electrical resistivity and Hall effect measurements were performed on the films with van der Pauw configuration. The temperature-dependent conductivity was performed in the range 20-300 K. Three types of conduction mechanisms were expected. Thermally activated band conduction at the high temperature range (250-300 K), Mott variable-range hopping (Mott-VRH) at the low temperature range (100-210 K) and Efros-Shklovskii variable-range hopping (ES-VRH) at the very low temperature range (<100 K) can be found in the films prepared with different oxygen flow rate conditions. Except for the oxygen flow rate at 5 sccm, the behavior of weakly localized electrons was observed. Then, the sets of parameters explaining the properties of localized electrons in each conduction regime were determined. The results indicated that the reactive dc magnetron sputtering using a single metallic Zn:Al (2 wt.% Al) target is suitable for TCO films since it can be easily obtained at low temperatures with good physical properties.
Preparation and characterization of bakelite bonded magnet NdFeB used for electric generator
Authors: Ramlan Ramlan , Setibudidaya Dedi , Bama A Aminudin , Muljadi Muljadi , Djuhana Djuhana 
Published: April 2020

AbstractThe permanent magnets based on NdFeB is well known as rare earth alloy magnets made from neodymium, iron and boron elements and has tetragonal crystalline structure Nd2Fe14B which has high coercivity, large energy product (app 50 MGOe) and curie temperature about 312 °C. In this paper will be discussed the preparation of bakelite bonded magnet NdFeB and characterization, also the purpose of this research is to make bonded magnet NdFeB using 3 % bakelite and know the extent to which can be applied in making a small electric generator. The bonded magnet NdFeB was made by mixing a magnetic powder NdFeB with a polymer as binder. The composition of the sample consisted of 97 wt. % of NdFeB powder and 3 wt.% of bakelite. The mixed raw materials were then pressed to form a disc with pressure about 40 MPa at temperature about 160 °C for 20 minutes. It was obtained a disc with size 40 x 18 x 6 mm. The disc samples were magnetized by using impulse magnetizer at 1500 Volt DC, then the samples were measured magnetic properties by using Gauss meter and Permeagraph. The measurements result show that, the bakelite bonded magnet NdFeB has Magnetic Flux = 1100 Gauss, Remanence Br = 5.20 kGauss, Coercivity Hc = 6.14 kOe and Energy product (BH) max = 4.78 MGOe. The bonded magnet NdFeB was applied to the prototype small generator with single rotor and single stator. The results of performance test of generator indicate that it is achieved output power of generator about 9.98 Watt at a maximum speed about 500 rpm.
The potential of tropical fruit peels as ion exchangers for water hardness removal
Authors: Tan Yee-Huan , Kerk Chee-Chian , Lee Chew-Tin , Cheok Choon-Yoong 
Published: April 2020

Abstract
The presence of high amount of mineral compounds such as calcium (Ca2+) and magnesium (Mg2+) in water attributed to occurrence of water hardness. Hard water causes lime scale in the kettle when boiling, and forms reddish brown stains on the clothes after washing. This study was carried out to investigate peels of durian, jackfruit and passion fruit as a potential cation exchanger for water hardness removal determining by EDTA titration. A synthetic hard water of 714.05 mg CaCO3/L was prepared to evaluate the removal efficiency of cation exchangers prepared from raw and sodium hydroxide-citric acid (NaOH-CA) modified fruit peels for 30 min, 60 min, and 90 min contact times. Results showed that raw peel of durian had the highest (p ≤ 0.05) efficiency (24%) for water hardness removal followed by jackfruit (21.87%) and passion fruit (6.5%). This was because the total cellulose content in durian peel powder and fibre was higher as compared to jackfruit peel and passion fruit peel. Hydroxyl group in the cellulose was the main group responsible in ion exchange with Ca2+ and Mg2+ for water hardness removal. For NaOH-CA modified peels, jackfruit demonstrated the highest (p ≤ 0.05) water hardness removal efficiency (62.05%) as compared to passion fruit (29.63%) and durian (10.42%) for 90 min contact time. This phenomenon can be explained by citric acid anhydride produced from esterification. Citric acid anhydride produced was combined with hydroxyl groups of cellulose and hemicellulose and formed the ester linkage and increased the number of carboxylate groups on the ion exchange surface. Result showed that water retention capacity is directly proportional to water hardness removal efficiency for modified fruit peels (R2 = 0.8181). This evidence that water retention capacity of lignocellulosic material is a good indicator of cross-linking which has a direct effect on ion exchange capability. Both raw durian peel and NaOH-CA modified jackfruit peel showed great ability in water hardness removal, hence the cost of chemicals involved in modification has to be considered for a good recommendation as great potential lignocellulosic material to be used for water hardness removal.
Nanoparticles filled PVA/PVDF hollow fiber membrane towards enhanced performance for air dehumidification
Authors: Liu Y.L. , Su J.C. , Cui X. , Zhang S.C. , Meng X.Z. , Jin L.W. 
Published: April 2020

Abstract
Membrane-based technology for gas separation has great potential in HVAC (Heating, Ventilating, and Air Conditioning) industry. In this research, the nanoparticle filled poly(vinyl alcohol)/poly(vinylidene fluoride) (PVA/PVDF) hollow fiber membrane was fabricated for indoor air dehumidification. The Poly(vinyl alcohol) thin film incorporated with nanoparticles was coated in the cavity of the Poly(vinylidene fluoride) substrate membranes. The enhanced performance of three types of nanoparticles [Zeolite, Titanium Dioxide (TiO2) and Graphene Oxide (GO)] was investigated experimentally for evaluating the water vapor permeability. The effects of nanoparticle types and nanoparticle loading concentration on the permeability enhancement of the nanoparticles filled PVA/PVDF membrane were compared and analyzed. The results indicate that the nanoparticles additives of great benefit to the performance improvement of water vapor permeability. The enhancement performance of three nanoparticles is as follows: Zeolite > GO > TiO2. The addition of 0.05 wt% Zeolite nanoparticles lead to twice enhancement on the water vapor permeance than the original PVA/PVDF membranes. The GO nanoparticle additive enhances the water vapor permeance to around 1500 GPU (gas permeation unit) with the nanoparticle concentration from 0.1 wt% to 0.2 wt%. However, the addition of TiO2 nanoparticle has no obvious enhancement due to its large particle size. This work provides a new perspective for strengthening the air dehumidification performance of composite membrane.
Feasibility on development of kinetic-energy harvesting floors
Authors: Lowattanamart W. , Suttisung V. , Sintragoonchai S. , Phanomchoeng G. , Jintanawan T. 
Published: April 2020

Abstract
Electricity consumption in big cities has been increasing, especially in crowded areas. Although there is a large amount of energy usage in such places, people can generate the unnoticeable electrical energy from their footsteps. This paper aims to present the feasibility on development of an energy harvesting floor—called Genpath—using a rotational electromagnetic (EM) technique to generate electricity from the human’s footsteps. The system in Genpath comprises two main parts: the EM generator and the power management and storage circuit. After stepping over the floor, a rack-pinion mechanism under the floor converses the linear translation from a footstep into the rotation to drive a DC-generator to generate electricity. The EM generator yields an average energy per footstep of about 199 mJ (or average power of 331 mW) and the maximal voltage of 19 V at the rated 140-Ω load resistance. This amount of energy is sufficient for low power consumption electrical devices. The efficiency of the EM generator in Genpath is 16.6% based on the power generation from the heel strike of the human’s walk of 2 W per step. Among overall energy generated by the generator, 68% of generated energy is stored in the 9-V rechargeable batteries and the rest is supplied to the 4-V, LED instantaneous loads. The power management and storage circuit consisting of the diodes and DC-DC buck voltage converters was successfully designed. With 54% efficiency of the circuit, the average energy per step of 169 mJ can be stored in the rechargeable battery, and the other 4.7 mJ can be supplied to the LED loads.
Effect of rotor length on generating power in horizontal axis wind turbines
Authors: Nasab Navid Majdi , Kilby Jeff , Bakhtiaryfard Leila 
Published: April 2020

Abstract
The benefits of the rotor design are optimizing power generation and reducing cost of build in wind turbines. In this study, a performance comparison of horizontal axis wind turbines in terms of their rotor diameter is made using Qblade software. The airfoil selected is the National Advisory Committee for Aeronautics (NACA 0012) for all models, and the wind turbines have three blades. From simulations, the optimal rpm for each rotor diameter was calculated, and the generated power for different wind speeds.
The results found show that the operation of wind turbines consider need operated with tip speed ratios of between 4 to 7 to give optimal power output. Maximum power was produced for a blade diameter of 170 metres and the highest power coefficient found was for a diameter of 30 metres and for this case also had the highest tip speed ratio of 6.68. Overall results can suggest which diameter range is used for choosing a rotor size that is the most cost-effective.
On stability of time marching in numerical solutions of rayleigh-plesset equation for ultrasonic cavitation
Authors: Tey Wah Yen , Alehossein Habib , Qin Zonyi , Lee Kiat Moon , Kang Hooi Siang , Lee Kee Quen 
Published: April 2020

Abstract
Ultrasonic irradiation approach has become one of the most popular methods applied in chemical processing including lignocellulosic biomass pretreatment and industrial cleansing. The phenomenon of ultrasonic cavitation can be indeed delineated via the Rayleigh-Plesset equation (RPE), which governs the transient radius of the bubble. Nonetheless, the time marching in the numerical solutions for RPE is highly unstable, which cannot be assured using von Neumann analysis. High sensitivity of RPE to time step may lead to extremely long computational time. The lack of numerical investigation into the time stepping issue of RPE has hindered in-depth simulation of ultrasonic cavitation. Therefore, the purpose of this paper is to investigate the stability criterion of time stepping for RPE in different time progression schemes, namely Euler explicit, 2nd order Taylor’s method, 4th order Runge-Kutta, Runge-Kutta Fehlberg and Cash-Karp Runge-Kutta method. A simple modified adaptive time step method and α independence study has been introduced in this paper for fast, stable and accurate computation of RPE. Compared with the traditional constant time marching method, the new model is able to improve the computational cost significantly without affecting the time marching stability and resolution of the results. Among the investigated method, Runge-Kutta family solvers have higher computational accuracy, with the cost of higher critical α value. The model is also applied to compute the pressure and temperature hike during bubble collapse due to different sonication power. The simulation results show that the ultrasonic irradiation with higher sonication power could produce a higher energy to break the lignocellulose wall.
Flow analysis of the deep dynamic stall of wind turbine airfoil with single-row and double-row passive vortex generators
Authors: Zhu Chengyong , Wang Tongguang , Chen Jie , Zhong Wei 
Published: April 2020

Abstract
This paper aims to understand the influence of vortex generators (VGs) on deep dynamic stall of the NREL S809 airfoil. The fully-resolved URANS method is used to predict aerodynamic responses of the airfoil with both single-row and double-row VGs. On one hand, single-row and double-row VGs are found to attenuate the force fluctuation and postpone the extension of flow separation when the airfoil pitches up. The onset of deep dynamic stall is therefore significantly delayed with the maximum lift coefficient increased beyond 40%. This indicates that VGs are effective in controlling deep dynamic-stall behavior. On the other hand, single-row and double-row VGs are found to make a great difference in aerodynamic responses when the airfoil pitches down. Single-row VGs undermine the torsional aeroelastic stability and have the potential risk of making the airfoil flutter. Double-row VGs can accelerate the flow reattachment effectively, and quickly restore the decreased aerodynamic force near the maximum angle of attack. These findings also imply that deep dynamic stall with VGs becomes highly complicated, because VGs can be fully submerged in separation vortices. In general, double-row VGs perform better than single-row VGs to control deep dynamic stall. This study is believed to assess the VG performance in controlling highly unsteady aerodynamic loads on wind turbines.
The effect of pretreatment methods for improved biogas production from oil-palm empty fruit bunches (EFB): experimental and model
Authors: Wadchasit Pornwimon , Siripattana Chairat , Nuithitikul Kamchai 
Published: April 2020

Abstract
The production of biogas from solid wastes in addition to palm oil mill effluents is necessary due to the shortage of the effluents, operation of biogas plants at low to moderate capacities, and large amount of solid wastes, particularly oil-palm empty fruit bunches (EFB). However, the biogas production from raw EFB gives low yield. This study therefore aims to investigate the effect of EFB pretreatment methods on the improvement of biogas production. The pretreatment of EFB was carried out through chemical (NaOH solutions), physical (size reduction) and biological (activated sludge and bio-scrubber effluent) processes. The experimental data was tested against corrected Gompertz model. The results showed that size reduction and pretreatments of EFB with 7% w/v NaOH, activated sludge and bio-scrubber effluent could improve biogas yield significantly and differently. The highest yield of methane was 429.9 ml/g.VS, obtained from EFB with size reduction. For the pretreatments of EFB with 7% w/v NaOH, bio-scrubber effluent and activated sludge, the methane yields were 345.5, 326.4 and 297.3 ml/g.VS, respectively. Without pretreatment, the methane yield was only 226.0 ml/g.VS. The change in cellulose and lignin compositions of EFB after pretreatment is attributed to the improvement of biogas yield. It is economically interesting that the bio-scrubber effluent from palm oil mills can be recycled to treat EFB. In the modeling study, the corrected Gompertz model could fit all data sets reasonably well.
Parameters estimation of hydraulic power take-off system for wave energy conversion system using genetic algorithm
Authors: Jusoh M. A. , Ibrahim M. Z. , Daud M. Z. , Yusop Z. M. , Albani A. , Rahman S. J. , Mohad S. 
Published: April 2020

Abstract
This paper presents accurate control parameters estimation of the hydraulic Power Take-Off (PTO) model for the wave energy conversion system to maximise energy production. In general, the performance of the hydraulic PTO system depends on the parameters setting of hydraulic PTO system components such as hydraulic motor displacement setting, pre-charge of the hydraulic accumulator, and et cetera. Conventionally, it requires to manually obtain the optimal parameters of a hydraulic PTO system by repeating the simulation process. However, this estimation method exposed to human error and would easily be resulting in a non-optimal selection of hydraulic PTO parameters for the wave energy conversion system. Therefore, an easy and accurate approach of using the GA optimisation method for determining hydraulic PTO parameters was introduced in the present study. This approach is simple and more accurate compared to the conventional optimisation method. The hydraulic PTO model was developed in SIEMENS/Amesim environment using available components in the library. The specifications of the actual hydraulic PTO system components from the manufacturer were used during the simulation set-up. The complete hydraulic PTO system was optimised using a special genetic algorithm (GA) optimisation tools in the SIEMENS/Amesim software. The simulation results showed that GA was effective to determine the optimal configuration parameters of hydraulic PTO system. From the results, the optimal configuration parameters of hydraulic PTO system were successfully reduced about 38%. Consequently, the maximum force applied to the WEC devices was reduced up to 34%. This force reduction is important since it will enable the WECS to be operated during a smaller wave condition.
Performance analysis of solar tunnel dryer with thermal storage and Photovoltaic system for drying star fruit
Authors: Kondareddy Rajesh , Sivakumaran N , Radhakrishnan K. , Nayak Prakash Kumar 
Published: April 2020

Abstract
The aim of this research work to analyse the performance of the proposed solar tunnel dryer and photovoltaic (PV) system to dry star fruit. Star fruit (Averrhoa carambola L.) is a native fruit in the north eastern states of India. Due to its rich nutritional composition and medicinal property, the demand for this fruit increased nationally. The proposed design consists of a tunnel type drying chamber and thermal storage unit. Paraffin wax (PCM) was used as a thermal storing material mounted in the tunnel dryer chamber to use the thermal energy at off sunshine hours. The thermal insulation coating on the outer surface of the solar drying chamber enhances the thermal performance of the tunnel dryer. The overall efficiency of this proposed design was analysed. The results indicated that drying of star fruit occurred in the falling rate period, where no constant rate period of drying rate was observed. The quality analyses data revealed that higher values of TPC (47.59 mg GAE/gram of sample) and DPPH (73.59 μ mol of TE/gram of sample) are obtained in the samples dried in solar dried as compared to open sun-dried samples. Sensory analysis (taste, aroma and flavour) carried out on slices of star fruit indicated that the solar-dried slices provided better scores compared to open sun-dried samples.
Optimal reactive power dispatch using particle swarm optimization algorithm for Yangon distribution network
Authors: Htay Tin Tin , Mon Khine Khine , Lin Ohn Zin 
Published: April 2020

Abstract
Optimal Reactive Power Dispatch (ORPD) is very efficient to optimize the control variables like as generator voltages, transformer tap setting and values of reactive power injection for loss reduction in power system. ORPD is the one of the complexity of optimization problems including with equality and inequality constraints of power systems. Many research papers have developed in ORPD applied to the IEEE test systems with various intelligent methods for the loss reduction. In this paper, the test system is carried out on Yangon Distribution Network (YDN) composed of different voltage level such as 230 kV, 66 kV and 33 kV, and supplied by various types of generation sources. Thus, it is very high in losses and difficult to find out the control variables of ORPD in YDN. The main objective is to reduce the both active and reactive power losses in YDN. Particle Swarm Optimization (PSO) method implemented in ORPD problem of YDN is very applicable and effective to obtain the minimum losses while all the bus voltage profile is acceptable in voltage constraints. The obtained results from ORPD using PSO algorithm could enhance YDN efficiently.
Qualitative framework based on intelligent robotics for safe and efficient disassembly of battery modules for recycling purposes
Authors: Garg Akhil , Zhou Lin , Zheng Jun , Gao Liang 
Published: April 2020

Abstract
In next 5-10 years, there will be 5-8 million tons of spent batteries accumulated as waste. There exists methods for recovery of materials from a battery for reuse or remanufacturing purposes. The research question arises on how about the recycling of batteries stacked in the battery modules in series or parallel configurations. This paper shall propose the qualitative framework based on intelligent robots for safer and efficient disassembly of battery modules for recycling. The framework combines the battery pack’s automatic removal procedure with the battery’s intelligent sorting program to recycle the reusable batteries. It has higher degree of automation and higher recycling efficiency than the existing frameworks. This also includes a smart battery information collection system (machine vision based information reading), an intelligent robot based battery disassembly system and a smart battery classification system. In addition, the framework also includes AI model based programming of robot so that it can sort out the batteries in ascending order of their remaining life.