bluuebunny/crossref_metadata_2025 huggingface dataset:
Microstructure and texture of high manganese steel subjected to dynamic impact loading
Authors: Eskandari M. , Szpunar J.A.
Published: April 2020

Dynamic impact response of high Mn-steel at a strain rate of 3000 s−1 was investigated using the Split Hopkinson Pressure bar. The investigated steel depicted continuous yielding at high strain rates. Additionally, the yield stress displayed a positive strain-rate sensitivity with an increasing strain rate. Microstructural evaluations displayed that strain-induced martensitic transformation and dislocation multiplication during slip were dominant plastic deformation mechanisms in the absence of deformation twinning which contributes to the strain hardening. Adiabatic shear band and martensite to austenite reversion or dynamic recrystallisation were also attributed to strain softening during impact deformation. The {001}<110> R-cube, {011}<110> R-Goss, and ({111}<110>) E texture components were strengthened after impact loading compared with as-received condition, while the intensities of Cube, Cupper, Brass, and S texture components were decreased.
On the processing properties and friction behaviours during compaction of powder mixtures
Authors: Chen Wenchao , Wang Jinghui , Wang Shiping , Chen Pengqi , Cheng Jigui
Published: April 2020

Iron-based powder mixtures were prepared by dry and wet mixing method. The friction properties during compaction were tested by measuring the internal and external friction coefficient. The test results showed that the wet mixing process could realise the homogeneity of lubricant and improve the processing properties of the powder mixtures. With 0.6 wt-% lubricants, wet mixing powder mixtures have a flow rate of 29.6 s/50 g, an apparent density of 3.18 g cm–3, a repose angle of 35.5°, and the friction coefficient during the compaction is 0.223. An equation to calculate the total (both internal and external) friction forces during the compaction process is proposed, and then the factors influencing the friction coefficient during compaction were quantitatively analysed.
Spatial planning for urban ventilation corridors by urban climatology
Authors: Gu Kangkang , Fang Yunhao , Qian Zhao , Sun Zhen , Wang Ai
Published: April 2020

Ventilation corridors in cities can decrease air pollution and alleviate heat island problems but there remains a need to fully assess their effectiveness. Few urban managers have been able to take city-scale approaches to the construction of urban ventilation corridors. This study aimed to introduced the Ventilation Corridor Planning (VCP) model, which is a multi-criteria evaluation method combined with a geographical information system (GIS) to determine where the ventilated environment is most appropriate. Specifically, the VCP model took Bozhou, China as the research object and contained two scales, including mesoscale and local scale. In mesoscale scale, we got three outputs to build urban ventilation corridors, including 1) background wind environment, 2) ventilation potential, 3) heat island intensity. In local scale, we used traditional computational fluid dynamics (CFD) model to verify the impact of VCP criteria. The results revealed that compared with the traditional CFD model, the proposed VCP model has advantages in establishing a comprehensive evaluation standard. In addition, the application of VCP model in macro and micro also enhances the efficiency of ventilation corridor construction. Overall, this study introduced a effective modeling method to urban ventilation corridors planning, and provide a way to study the urban climate.
Mitochondrial translation and dynamics synergistically extend lifespan in C. elegans through HLH-30
Authors: Liu Yasmine J. , McIntyre Rebecca L. , Janssens Georges E. , Williams Evan G. , Lan Jiayi , van Weeghel Michel , Schomakers Bauke , van der Veen Henk , van der Wel Nicole N. , Yao Pallas , Mair William B. , Aebersold Ruedi , MacInnes Alyson W. , Houtkooper Riekelt H.
Published: April 2020

Mitochondrial form and function are closely interlinked in homeostasis and aging. Inhibiting mitochondrial translation is known to increase lifespan in C. elegans, and is accompanied by a fragmented mitochondrial network. However, whether this link between mitochondrial translation and morphology is causal in longevity remains uncharacterized. Here, we show in C. elegans that disrupting mitochondrial network homeostasis by blocking fission or fusion synergizes with reduced mitochondrial translation to prolong lifespan and stimulate stress response such as the mitochondrial unfolded protein response, UPRMT. Conversely, immobilizing the mitochondrial network through a simultaneous disruption of fission and fusion abrogates the lifespan increase induced by mitochondrial translation inhibition. Furthermore, we find that the synergistic effect of inhibiting both mitochondrial translation and dynamics on lifespan, despite stimulating UPRMT, does not require it. Instead, this lifespan-extending synergy is exclusively dependent on the lysosome biogenesis and autophagy transcription factor HLH-30/TFEB. Altogether, our study reveals the mechanistic crosstalk between mitochondrial translation, mitochondrial dynamics, and lysosomal signaling in regulating longevity.
Wafer-scale nanofabrication of sub-100 nm arrays by deep-UV displacement Talbot lithography
Authors: Gómez Víctor J , Graczyk Mariusz , Jam Reza Jafari , Lehmann Sebastian , Maximov Ivan
Published: April 2020

In this manuscript, we demonstrate the potential of replacing the standard bottom anti-reflective coating (BARC) with a polymethylglutarimide (PMGI) layer for wafer-scale nanofabrication by means of deep-UV displacement talbot lithography (DTL). PMGI is functioning as a developable non-UV sensitive bottom anti-reflective coating (DBARC). After introducing the fabrication process using a standard BARC-based coating and the novel PMGI-based one, the DTL nanopatterning capabilities for both coatings are compared by means of the fabrication of etched nanoholes in a dielectric layer and metal nanodots made by lift-off. Improvement of DTL capabilities are attributed to a reduction of process complexity by avoiding the use of O2 plasma etching of the BARC layer. We show the capacity of this approach to produce nanoholes or nanodots with diameters ranging from 95 to 200 nm at a wafer-scale using only one mask and a proper exposing dose. The minimum diameter of the nanoholes is reduced from 118 to 95 nm when using the PMGI-based coating instead of the BARC-based one. The possibilities opened by the PMGI-based coating are illustrated by the successful fabrication of an array of nanoholes with sub-100 nm diameter for GaAs nanowire growth on a 2″ GaAs wafer, a 2″ nanoimprint lithography (NIL) master stamp, and an array of Au nanodots made by lift-off on a 4″ silica wafer. Therefore, DTL possess the potential for wafer-scale manufacturing of nano-engineered materials.
Low cost device to study static electricity and to verify the
polarity of the charge on the surface of the materials in the triboelectric
series
Authors: Lahane Rohan D , Paranjpye Arvind
Published: April 2020

Students are introduced to the concepts of static electricity at a school level
and an under-graduate level. In this paper, we present an inexpensive and
portable device that can be used to study the static electricity and verify
polarity of the electric charge on materials in a triboelectric series. This
device is developed at the Science Laboratory, Nehru Planetarium (Mumbai),
India. It has wide applications as an educational tool to teach the fundamental
concepts of electrostatics in a simpler way.
Tensile and fatigue testing of impacted smart CFRP composites with embedded PZT transducers for nonlinear ultrasonic monitoring of damage evolution
Authors: Andreades Christos , Meo Michele , Ciampa Francesco
Published: April 2020

Ultrasonic systems based on ‘smart’ composite structures with embedded sensor networks can reduce both inspection time and costs of aircraft components during maintenance or in-service. This paper assessed the tensile strength and fatigue endurance of carbon fibre reinforced plastic (CFRP) laminates with embedded piezoelectric (PZT) transducers, which were covered with glass fibre patches for electrical insulation. This sensor layout was proposed and tested by the authors in recent studies, proving its suitability for nonlinear ultrasonic detection of material damage without compromising the compressive, flexural or interlaminar shear strength of the ‘smart’ CFRP composite. In this work, CFRP samples including PZTs (G-specimens) were tested against plain samples (P-specimens), and their mean values of tensile strength and fatigue cycles to failure were found to be statistically the same (910 MPa and 713 000 cycles) using the one-way analysis of variance method. The same tests on P- and G-specimens with barely visible impact damage (BVID) showed that the corresponding group means were also the same (865 MPa and 675 000 cycles). Nonlinear ultrasonic experiments on impacted G-samples demonstrated that embedded PZTs could monitor the growth of BVID during fatigue testing, for a minimum of 480 000 cycles. This was achieved by calculating an increase of nearly two orders of magnitude in the ratio of second-to-fundamental harmonic amplitude. Finally, PZT transducers were confirmed functional under cyclic loading up to ∼70% of sample’s life, since their capacitance remained constant during ultrasonic testing.
Stray light analysis of the Xinglong 2.16-m telescope
Authors: Li Tao-Ran , Wang Jian-Feng , Zhang Xiao-Ming , Zhao Yong , Tian Jian-Feng
Published: April 2020

An effort towards understanding the problems associated with stray light related to the Xinglong 2.16-m telescope is presented to estimate the stray light performance of the telescope itself and provide a method for improving stray light suppression. Stray light analysis for the 2.16-m telescope model, which consists of an onion shaped dome, telescope structure, equatorial mount and telescope optics, has been developed in two cases (1) pointing to 60° and (2) pointing to zenith, in both azimuth and elevation directions. The Point Source Normalized Irradiance Transmittance (PSNIT), which is generally used for assessing stray light and is uncorrelated to entrance aperture, is calculated with a series of off-axis angles. It shows that the PSNIT values are less than 10−7 when off-axis angles are larger than ± 20°. The dominant contributors to stray light (primary and secondary mirror, telescope structure and dome) are identified to guide performance improvement. The analyses indicate that significant benefit can be realized by adding only five vanes inside the bottom portion of the secondary baffle. In the case of pointing to zenith, the PSNIT values will decrease about 40% on average.
Sun-Earth connection event of super geomagnetic storm on 2001 March 31: the importance of solar wind density
Authors: Cheng Li-Bin , Le Gui-Ming , Zhao Ming-Xian
Published: April 2020

An X1.7 flare at 10:15 UT and a halo CME with a projected speed of 942 km s−1 erupted from NOAA solar active region 9393 located at N20W19, which were observed on 2001 March 29. When the CME reached the Earth, it triggered a super geomagnetic storm (hereafter super storm). We find that the CME always moved towards the Earth according to the intensity-time profiles of protons with different energies. The solar wind parameters responsible for the main phase of the super storm occurred on 2001 March 31 are analyzed while taking into account the delayed geomagnetic effect of solar wind at the L1 point and using the SYM-H index. According to the variation properties of SYM-H index during the main phase of the super storm, the main phase of the super storm is divided into two parts. A comparative study of solar wind parameters responsible for two parts shows the evidence that the solar wind density plays a significant role in transferring solar wind energy into the magnetosphere, besides the southward magnetic field and solar wind speed.
The force-free dipole magnetosphere in nonlinear electrodynamics
Authors: Li Hui-Quan , Yang Xiao-Lin , Wang Jian-Cheng
Published: April 2020

Quantum electrodynamics (QED) effects may be included in physical processes of magnetar and pulsar magnetospheres with strong magnetic fields. Involving the quantum corrections, Maxwell electrodynamics is modified to nonlinear electrodynamics. In this work, we study the force-free magnetosphere in nonlinear electrodynamics in a general framework. The pulsar equation describing a steady and axisymmetric magnetosphere is derived, which now admits solutions with corrections. We derive the first-order nonlinear corrections to the near-zone dipole magnetosphere in some popular nonlinear effective theories. The field lines of the corrected dipole tend to converge on the rotational axis so that the fields in the polar region are stronger compared to the pure dipole case.
First time-resolved CCD photometry and time-series analysis of NSV 13601
Authors: Gohil Virabhadrasinh A. , Bhatnagar Sachchidanand Prakash
Published: April 2020

We present the first results of a time-resolved CCD photometric and time-series analysis of NSV 13601, a variable star in the constellation Pegasus. The 14″ Schmidt-Cassegrain telescope of Maharaja Krishnakumarsinhji Bhavnagar University (MKBU) was used for observations. Analysis was performed both in VStar and Period04 software, and their results were compared. The main results are as follows: From data analysis, its has period ∼77.784 d (MKBU data V) (VStar), ∼77.632 d (MKBU data Ic) (VStar), ∼77.058 d (MKBU data V) (Period04) and ∼49.560 d (MKBU data Ic) (Period04). Its V and I mean magnitudes for MKBU data are 12.203 (V) and 11.292 (I) mag respectively. We confirm it to be a variable star.
Binary star detection in the open cluster King 1 field
Authors: Saleh Parvej Reja , Hazarika Debasish , Dar Ajaz Ahmad , Parihar Padmakar Singh , Saikia Eeshankur
Published: April 2020

A rarely studied open cluster, King 1 is observed using the 1.3-m telescope equipped with a 2k × 4k CCD at Vainu Bappu Observatory, India. We analyze the photometric data obtained from CCD observations in both B and V bands. Out of 132 detected stars in the open cluster King 1 field, we have identified four stellar variables, and two among them are reported as newly detected binary systems. The parallax values from Gaia DR2 suggest that the open cluster King 1 is in the background of these two detected binary systems, falling along the same line of sight, giving rise to different parallax values. Periodogram analysis was carried out using Phase Dispersion Minimization (PDM) and the Lomb-Scargle (LS) method for all the detected variables. PHysics Of Eclipsing BinariEs (PHOEBE) is extensively employed to model various stellar parameters of both the detected binary systems. Based on the modeling results obtained from this work, one of the binary systems is reported for the first time as an Eclipsing Detached (ED) and the other as an Eclipsing Contact (EC) binary of W-type W UMa.
Investigation on the impact of papaya biodiesel-diesel blends on combustion of an agricultural CI engine
Authors: Anwar M , Rasul M G , Ashwath N
Published: April 2020

In this study, an overview of combustion characteristics of an agricultural diesel engine fuelled with papaya seed oil (PSO) biodiesel and diesel is presented. A naturally aspirated four-cylinder four-stroke tractor engine was used for all experiments. Various PSO blends (5%, 10%, and 20%) were tested and compared with diesel at speeds of 1400 rpm and 2400 rpm at full load condition. The combustion characteristics such as in-cylinder pressure, heat release rate, ignition delay, mass fraction burned, ignition duration and cylinder temperature were tested. The results show that PSO blends have some excellent attributes as fuel in regard to combustion characteristics. All PSO biodiesel blends have higher in-cylinder pressure; for example, PSO20 has 2.4% more than diesel. Heat release rate values of all PSO biodiesel blends were found to be lower than diesel due to the shorter ignition delay and lower calorific values of biodiesel. PSO20 biodiesel shows faster combustion than diesel by about 11.92% at 1400 rpm and 7.93% at 2400 rpm. The maximum cylinder temperature of all PSO biodiesel blends are also higher than that of diesel, such as PSO20 at 1400 rpm by 3.17% and at 2400 rpm by 3.73%.
Delignification of oil palm empty fruit bunch via ultrasound-assisted deep eutectic solvent pretreatment
Authors: Quek Joo Ding , Lee Kiat Moon , Lim Steven , Tey Wah Yen , Kang Hooi-Siang , Quen Lee Kee
Published: April 2020

Lignin is the complex organic polymers contain in lignocellulosic biomass, acting as structural support of the biomass. Its presence making the biomass recalcitrance to bioprocessing. Therefore, pretreatment is essential in removing the lignin content to enhance the sugar extraction and bioethanol production from lignocellulosic biomass. In this work, pretreatment of oil palm empty fruit bunch (OPEFB) using ultrasound-assisted deep eutectic solvents (DESs) was performed. Three types of DESs, namely choline chloride-lactic acid (ChCl-LA), choline chloride-glycerol (ChCl-G) and choline chloride-urea (ChCl-U) in delignification were studied. The pretreatment was conducted with the presence of ultrasonication. The DESs recyclability were also performed in this work. ChCl-LA exhibited the best delignification properties, in which ChCl-LA pretreated OPEFB had the lowest total lignin content of 18.8%, followed by ChCl-U (19.4%) and ChCl-G (21.2%). All the three DESs were successfully recycled with slight decrement in delignification performance after two recycles. The recyclability of the DESs would improve the economic feasibility of the pretreatment process.
Kinetic model of biogas production from co-digestion of Thai rice noodle wastewater with rice husk and different type of manure with ash supplement
Authors: Jijai Sunwanee , Muleng Saina , Noynoo Laddawan , Siripatana Chairat
Published: April 2020

In recent decades up to now, researches on alternative energies have been intensified particularly those on biomethane and biohydrogen from agriculture wastes and municipal wastes. The objective of this research was to study the biogas production from anaerobic co-digestion of Thai rice noodle wastewater with rice husk and different types of animal manure (chicken manure, cow manure, and quail manure), with and without ash supplement. There were 27 experiments conducted in batch digesters at room temperature (28-30 °C) and each experiment was triplicated. Each digester contained 10 g of animal manure, 10 g of rice husk, and 200 ml total working volumes of Thai rice noodle wastewater. Five different amounts of ashes (0, 2, 4, 6, 8 and 10 g) were supplemented. The results showed that the co-digestion of Thai rice noodle wastewater with chicken manure, rice husk, and 6 g of ash supplement gave the highest methane percentage, cumulative methane production and bio-methane potential (BMP): average value of 71.5%, 1,846 mL and 311.2 mLCH4/gVSremoved respectively. This co-digestion gave the initial pH of 7.0 and it was sustained in an optimal range (pH 6.8-7.5) until the digestion stopped (45 days). Slow release of nutrients from slowly digestible substrates helped to balance the digestion steps, sustaining pH to around 7. In contrary, other sub-optimal ratios produced the final pH was lower than its initial pH, and the AD process could fail or produced less methane. In the kinetic study, it was also found that traditional Gompertz and Monod-type models for single substrate digestion could not describe the biogas evolution curve satisfactory. Two-substrate models were used instead and able to describe the experimental data very well.
Assessment of the bioenergy policy for the sustainable development of rural-based bioenergy systems in Zambia
Authors: Kaoma M , Gheewala S H
Published: April 2020

Traditional biomass remains the primary energy source in rural Zambia – providing 98% of the energy needs. Its use is unsustainable, inefficient, and leads to harmful emissions with serious health implications, and deforestation. Modern bioenergy systems offer viable energy supply alternatives - but only if sustainably developed. Among other causes, the limited provision of modern bioenergy in rural areas is attributed to an ineffective public policy for promoting these systems in Zambia. Accordingly, this study evaluates the policy in place that seeks to promote sustainable bioenergy systems for rural areas in Zambia through the analysis of related strategies. It is observed that one of the significant weaknesses of the bioenergy policy framework is its lack of consideration of the bioenergy supply chains. These are influenced by four main elements – i.e., feedstock availability, conversion technology, intermediate energy carriers, and energy service demands - that considerably differ across rural localities within districts. Thus, the bioenergy policy-making process should be considered at such subnational levels (district). A suggestion that is well-aligned with the country’s decentralized governance agenda that is being implemented. Considering that there are numerous rural communities within a district and that information regarding the different elements of the bioenergy supply chain is required for the local government policy-making process, a framework to guide the generation of such information has been proposed.
Application of 3D printed structured materials as the sound absorption panels
Authors: King Yeong-Jin , Teo Keng-Kai
Published: April 2020

The human living standard has been increasing day-by-day. Not only the building energy performance has to meet a high expectation, but the noise quality of a building has to be par with it. Sound absorption is one of the key elements in determining the quality of the acoustics performance in a room. A room with high background noise and high reverberant time will affect the comfort level of the occupants in the room. Hence, a well-designed room with acoustics treatment is required. The sound absorptive materials play an important role in reducing the overall sound pressure level in the room. Conventionally sound absorber materials are porous and resonator. With the advancement of the addictive technology, the sound insulation materials can be further improved and optimized with 3D printed structured materials. Two 3D printed structured designs have been developed in this study and were printed out by using fused deposited modelling in 3D printing technology. The two designs are micro perforated design (MPP) and porous design. The structured materials have been tested for its sound absorption ability using the sound impedance tube. The frequency range tested is between 100 Hz to 6400 Hz. In conclusion, micro perforated design (MPP) model has a very good sound absorptive behavior at the low frequency at 4000Hz and below, whereas the porous model is effective at high frequency at the 2500Hz and above. Through the study, the perforation ratio is found to be closely related to the peak sound absorption coefficient frequency. The peak frequency is reduced with the increase of the perforation ratio. The gap between the 3D printed structured materials and end wall also play the important role. The larger the gap, the lower the peak absorptive frequency.
Utilization of waste material for aerated autoclaved concrete production: A preliminary review
Authors: Rahman R.A. , Fazlizan A. , Asim N. , Thongtha A.
Published: April 2020

Autoclaved aerated concrete (AAC) has become more attractive in construction due to its excellent environmentally friendly in building construction. Due to its increasing applications, the AAC wastes become abundance in construction site. Apparently, recycling the concrete waste powder to a wall concrete, particularly an autoclaved aerated concrete (AAC) was not frequently practiced in construction and moreover no study has been carried out yet. AAC is relatively lightweight, having lower thermal conductivity, higher heat resistance, lower shrinkage, and faster in construction process compared to normal concrete. AAC concrete is a combination of silica sand, cement, lime, water and an expansion agent. To improve its physical and mechanical properties and to reduce its production cost, tremendous innovation which used waste materials as partial replacement of AAC materials have been done. From these innovations, the use of recycled AAC as a partial replacement for wall concrete has not been carried out yet. This paper is intended to classify the literatures on the innovations that have been done on replacement in AAC materials to enhance its physical and mechanical properties and thermal performance. The physical properties in terms of its microstructure and the mechanical properties such as density, compressive strength, water absorption are presented to classify the investigation that has been done in such innovations. Apart of that, the discussion on innovations to improve its thermal performance also presented. To conclude, up to now, there is no attempt on using the recycled AAC waste powder as a partial replacement in AAC as a wall concrete is reported.
CO2 emissions from electricity generation in ASEAN: An empirical spatial-temporal index decomposition analysis
Authors: Goh Tian , Ang B W
Published: April 2020

The Association of Southeast Asian Nations (ASEAN) is a developing region that is poised to be one of the key contributors to rising CO2 emissions in the future. In particular, the electricity sector’s emissions have risen by 2.4 times since 2000 and may increase by another 2.6 times by 2040, motivated by the burgeoning regional energy demand. If realised, this growth in CO2 emissions could stall global climate mitigation and sustainability efforts. The electricity sector, however, has a large potential for decarbonization. To reveal the driving factors of historical trends, spatial-temporal index decomposition analyses (ST-IDA) based on the logarithmic mean Divisia index (LMDI) is applied to analyse ASEAN’s aggregate carbon intensity (ACI) of electricity from 2000 to 2015. The technique combines temporal and spatial data to reveal the factors influencing regional trends and allow for comparisons across countries. The results show that in the face of rapidly rising electricity demands, many ASEAN countries have failed to maintain consistent improvements in the ACI through the adoption of renewable energy or improvement in generation mix. While some countries have switched to cleaner forms of generation such as natural gas, varying energy resource endowments, national circumstances and energy demand trends are challenges to the adoption of renewable energy. Pressures from energy demand and technological challenges also prevent some countries from sustaining overall improvements in generation efficiencies of fossil fuel plants. Improving energy planning, demand management and greater regional cooperation are key to the decarbonisation of the electricity system.
Analysis and improvement on reliability of 66/11 kV distribution substation and its associated feeders: A case study of Lainchour substation in Nepal
Authors: Oli Sabin , Neupane Bodh Nath , Shrestha Namrata Tusuju , Mishra Brajesh , Shrestha Pramish
Published: April 2020

Electric power interruption is becoming a day to day phenomenon in our distribution system. For distribution system to be effective there should be less outage in the system and if fault occur these faults should be cleared as soon as possible. Sustained power interruption occurs several times a day from few minutes to hours. Interruptions may be due to failure of substation equipment or failure of distribution network elements. This paper attempts to identify different causes of interruption and problems that customers in Nepal have been facing due to frequent planned and unplanned sustained interruptions by evaluating various reliability indices and parameters of Lainchaur distribution substation and its associated feeders operated under Nepal Electricity Authority. First, reliability analysis of substation configuration only is done followed by analysis of reliability improvement measures like use of double bus bar, parallel distribution feeders and underground cables in DIgSILENT PowerFactory only considering sustained failures of equipment and feeders. Calculated reliability indices like System Average interruption Duration Index (SAIDI), System Average Interruption Frequency Index (SAIFI), Energy Not Served (ENS) are compared for different cases so that it will be easy to make choice between options to the utility to upgrade/improve the system. Considering all feeders, result shows that main cause of interruption in the distribution system is failure of distribution lines showing 104 interruptions for total duration of 107 hours per annum in the system, followed by failure of distribution transformers indicating 19 interruptions for total duration of 47 hours per annum. Simulation result in DIgSILENT shows yearly total ENS of distribution system is high due to present configuration, and can be reduced by the use of parallel feeders and underground cables respectively. It is seen that ENS due to failure of substation components only is very low and huge revenues can be saved if auto-reclosures are used or a provision of charging feeders as soon as possible is made.
Multi-objective optimal synthesis of algal biorefineries toward a sustainable circular bioeconomy
Authors: Solis C A , Mayol A P , San Juan J G , Ubando A T , Culaba A B
Published: April 2020

Production of biodiesel from renewable resources like microalgae biomass presents a potential for reduction of greenhouse gas emissions and fossil fuel energy consumption. The integration of processes from other industries have been implemented in microalgal biorefineries to increase economic sustainability by co-producing several high-value algal-based products. Agro-industrial processes have the potential to be incorporated into the biorefinery because it requires input material flows from other biorefinery process units to cultivate and sell crops for an additional source of revenue and increased carbon sequestration, while generating wastewater that may be used as a cultivation medium for algae or as a resource for other biorefinery processes. Circular bioeconomy, an extension of the circular economy ideology, has the goal of achieving economic and environmental sustainability through maximizing the dedicated recirculation of resource flows, and minimizing waste generation and end-of-life disposal. However, existing modelling studies have not explored this opportunity; previous studies have not considered that resource functionality runs out with repeated recirculation and reuse as it reaches its end of life. In this work, a novel multi-objective optimization model is developed to design and manage closed-loop algal biorefineries integrating agro-industrial processes that captures the effect of recirculation on resource material viability and end-of-life environmental impact. A case study is solved as proof of concept and to illustrate the design methodology, optimal solutions based on economic and environmental performance are analyzed. The results of the case study validate the initial hypothesis that there is a conflict between the economic and environmental objectives since the decision for biofuel production varied for each single objective. With the multi objective model, a balance between the two objectives was found. The results of the optimization model can be applied in the design of an algal biorefinery along with the decisions relating to production quantities incorporating a zero waste outlook.
Combustion characteristics of direct injection hydrogen in noble gases atmosphere
Authors: Taib Norhidayah Mat , Abu Mansor Mohd Radzi , Wan Mahmood Wan Mohd Faizal
Published: April 2020

Hydrogen combustion in the internal combustion engine (ICE) has currently taken part in the transportation industry due to its environmentally friendly and high engine thermal efficiency. Hydrogen direct injection introduction in the internal combustion engine eliminates the harmful emission from carbon and improves engine stability. The substitution from nitrogen to noble gases for the intake will solve the high auto-ignition temperature of hydrogen in compression ignition (CI) engine problem. This paper intended to study the combustion characteristics of direct injection hydrogen in oxygen-noble gas atmosphere such as argon and helium to find the suitable engine and injection parameters for the optimum engine efficiency. The simulation conducted using Converge CFD V2.4 software based on Yanmar NF19K direct injection CI engine. The simulation was done for different oxygen-noble gases such as argon, neon, and helium, while the injection timing and ambient temperature were modified to optimize the hydrogen combustion characteristics. The study found that noble gases help to increase the in-cylinder temperature and ignite the hydrogen. The study also found that early injection timing results in the highest in-cylinder pressure. Besides, increasing ambient temperature for intake decreases the in-cylinder pressure and lengthen the ignition delay. Therefore, the most suitable injection parameter for the most optimum hydrogen combustion characteristics is 380 K ambient temperature, early injection timing at -10°CA, and higher injection pressure. Helium produced higher in-cylinder peak pressure compared to argon due to its high specific heat ratio. Hence, further consideration of helium and good injection strategies should be applied for better engine thermal efficiency.
Effect on changing of intake temperature to hydrogen-methane-diesel mixture combustion characteristics
Authors: Sabah Osama , Mohammad Taib Iskandar , Abu Mansor Mohd Radzi
Published: April 2020

Ultra clean fuels generally used along with the conventional fuels such as Compressed Natural Gas (CNG) and hydrogen. The implementation of these alternatives can help take care to the high demand of environment friendly vehicles. These natural gas fuels when blended with diesel are expected to decrease emissions along-with reduction of the petroleum fuel consumption. Diesel mixed with hydrogen and methane in different concentrations enhances the performance and efficiency of vehicles. A numerical study were conducted to observe the impact of diesel mixed with hydrogen and methane (dual or tri-fuel) in the combustion process. Intake temperature was increased in between 303 K to 338 K. The simulation of the combustion process used ANSYS Fluent software based on a Yanmar L100AED single-cylinder engine parameter. The simulation conducted with engine speed of 1500 rpm, compression ratio (CR) = 19.3, and λ = 1.2 at different intake temperatures. The results compared the combustion process between a baseline fuel (100% diesel) and diesel-hydrogen-methane tri-fuel. The study found that the optimum intake temperature to enhance performance relies on a concentration of gaseous mixed with diesel. The highest performance and efficiency were obtained at 318 K intake temperature using tri-fuel of 60D-28H-12CH4. From the in-cylinder pressure and temperature, results show increased in performance when the amount of hydrogen increased at the intake temperature. In conclusion, increasing the intake temperature and the use of tri-fuel in a direct ignition engine significantly improved the performance and efficiency of the engine.
Catalytic activity of Pt/graphene prepared by strong electrostatic adsorption technique for proton exchange membrane fuel cells
Authors: Sukanya P , Konlayutt P
Published: April 2020

In the proton exchange membrane (PEM) fuel cell development, the catalytic activity requires the smaller particle size, the better metal dispersion, the higher conductivity and the longer durability. With these, platinum on graphene was synthesized using the strong electrostatic adsorption (SEA) technique. The pH shifts of graphene was evaluated and the point of zero charge (PZC) was obtained at pH about 5.2. This was a mid-low PZC, where the positive charge of Pt (i.e, platinum tetraamine, [NH3]4Pt2+or PTA) was chosen as the metal precursor. The adsorption of PTA precursor on graphene was carried out at pH of 12 for one hour at room temperature. PTA on graphene was reduced in hydrogen environment, and transferred to Pt metal particle. The adsorption and reduction steps were repeat until the Pt metals percentage closed to 20%wt Pt/C (i.e, 19.3 % wt. for this work). The prepared Pt/graphene catalyst shows the smaller particle size that average particle size as 2.4 nm and highly better dispersion than the Pt/C-commercial. The Pt metal dispersion on the graphene support were inspected by transmission electron microscopy (TEM). The crystal structures and crystalline size were investigated by X-ray diffraction (XRD). Moreover, the electrochemical properties were tested using cyclic voltammetry (CV) and the accelerated durability test (ADT) was also carried out after 4000 cycles of reduction and oxidation reaction. Finally, the results were compared with the 20% wt. Pt/C-commercial catalysts. It was observed that the oxidation reduction reaction (ORR) activity in terms of mass activity (MA) and specific activity (SA) were better than Pt/C-commercial.
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

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

The 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

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

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

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

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.