Sodium-ion batteries (SIBs) have great potential to be the next major energy storage devices due to their obvious advantages and developing advanced electrodes and electrolytes is urgently necessary to promote its fut...Sodium-ion batteries (SIBs) have great potential to be the next major energy storage devices due to their obvious advantages and developing advanced electrodes and electrolytes is urgently necessary to promote its future industrialization.However,hard carbon as a state-of-the-art anode of SIBs still suffers from the low initial Coulomb efficiency and unsatisfactory rate capability,which could be improved by forming desirable solid electrolyte interphases (SEI) to some extent.Indeed,the chemistry and morphology of these interfacial layers are fundamental parameters affecting the overall battery operation,and optimizing the electrolyte to dictate the quality of SEI on hard carbon is a key strategy.Hence,this review summarizes the recent research on SEI design by electrolyte manipulation from solvents,salts,and additives.It also presents some potential mechanisms of SEI formation in various electrolyte systems.Besides,the current advanced characterization techniques for electrolyte and SEI structure analyses have been comprehensively discussed.Lastly,current challenges and future perspectives of SEI formation on hard carbon anode for SIBs are provided from the viewpoints of its compositions,evolution processes,structures,and characterization techniques,which will promote SEI efficient manipulation and improve the performance of hard carbon,and further contribute to the development of SIBs.展开更多
A novel shrouded wind-solar hybrid renewable energy and rain water harvester with an omni-directional-guide-vane(ODGV) for urban high-rise application is introduced.The ODGV surrounds the vertical axis wind turbine(VA...A novel shrouded wind-solar hybrid renewable energy and rain water harvester with an omni-directional-guide-vane(ODGV) for urban high-rise application is introduced.The ODGV surrounds the vertical axis wind turbine(VAWT) and enhances the VAWT performance by increasing the on-coming wind speed and guiding it to an optimum flow angle before it interacts with the rotor blades.An ODGV scaled model was built and tested in the laboratory.The experimental results show that the rotational speed of the VAWT increases by about 2 times.Simulations show that the installation of the ODGV increases the torque output of a single-bladed VAWT by 206% for tip speed ratio of 0.4.The result also reveals that higher positive torque can be achieved when the blade tangential force at all radial positions is optimized.In conclusion,the ODGV improves the power output of a VAWT and this integrated design promotes the installation of wind energy systems in urban areas.展开更多
Photovoltaic(PV)systems are adversely affected by partial shading and non-uniform conditions.Meanwhile,the addition of a bypass shunt diode to each PV module prevents hotspots.It also produces numerous peaks in the PV...Photovoltaic(PV)systems are adversely affected by partial shading and non-uniform conditions.Meanwhile,the addition of a bypass shunt diode to each PV module prevents hotspots.It also produces numerous peaks in the PV array’s power-voltage characteristics,thereby trapping conventional maximum power point tracking(MPPT)methods in local peaks.Swarm optimization approaches can be used to address this issue.However,these strategies have an unreasonably long convergence time.The Grey Wolf Optimizer(GWO)is a fast and more dependable optimization algorithm.This renders it a good option for MPPT of PV systems operating in varying partial shading.The conventional GWO method involves a long conversion time,large steady-state oscillations,and a high failure rate.This work attempts to address these issues by combining Cuckoo Search(CS)with the GWO algorithm to improve the MPPT performance.The results of this approach are compared with those of conventional MPPT according to GWO and MPPT methods based on perturb and observe(P&O).A comparative analysis reveals that under non-uniform operating conditions,the hybrid GWO CS(GWOCS)approach presented in this article outperforms the GWO and P&O approaches.展开更多
A two-phase dynamic model, describing gas phase propylene polymerization in a fluidized bed reactor, was used to explore the dynamic behavior and process control of the polypropylene production rate and reactor temper...A two-phase dynamic model, describing gas phase propylene polymerization in a fluidized bed reactor, was used to explore the dynamic behavior and process control of the polypropylene production rate and reactor temperature. The open loop analysis revealed the nonlinear behavior of the polypropylene fluidized bed reactor, jus- tifying the use of an advanced control algorithm for efficient control of the process variables. In this case, a central- ized model predictive control （MPC） technique was implemented to control the polypropylene production rate and reactor temperature by manipulating the catalyst feed rate and cooling water flow rate respectively. The corre- sponding MPC controller was able to track changes in the setpoint smoothly for the reactor temperature and pro- duction rate while the setpoint tracking of the conventional proportional-integral （PI） controller was oscillatory with overshoots and obvious interaction between the reactor temperature and production rate loops. The MPC was able to produce controller moves which not only were well within the specified input constraints for both control vari- ables, but also non-aggressive and sufficiently smooth for practical implementations. Furthermore, the closed loop dynamic simulations indicated that the speed of rejecting the process disturbances for the MPC controller were also acceotable for both controlled variables.展开更多
Malaysia is one of the many countries that experience high lightning related activities. In fact, according to Malaysian Meteorological Department the Ground Flash Density (GFD) in Malaysia, it is rated at the fifth p...Malaysia is one of the many countries that experience high lightning related activities. In fact, according to Malaysian Meteorological Department the Ground Flash Density (GFD) in Malaysia, it is rated at the fifth place in the ten most lightning cities of the world, with a high keraunic level, which is 240 thunderstorm days per year, and in other words, a Ground Flash Density (GFD) of 48.3 flashes per square kilometer per year. In the power systems, high keraunic level would contribute to high possibility of power interruptions such as disruption, degradation, damage and downtime. These outages would ultimately lead to revenue losses and reduction of network reliability. These lightning related interruptions may be in terms of direct lightning strikes to the lines or to the equipments in the substation. By the use of Mat Lab GUI (Graphic Users Interface), this study presents a simple computer program which uses the electro-geometric model (EGM) for the designing of substation shielding systems. The EGM uses the concept where the protection zone of a lightning system lies within the radius where the upward channel initiates and propagates through the air terminal to meet the downward leader. This interception point is called “the point of discrimination” and is where the downward leader decides its final jump. The distance at which the last jump occurs is known as the striking distance. With the use of the striking distance and the mathematical equations developed by Young, Brown-Whitehead, IEEE-1992 (IEEE T&D Committee Equations) and IEEE-1995 (IEEE Substations Committee Equations). This project aimed to investigate, understand and analyse the substation protection by means of masts and shield wires. The analysis is extended to account for lightning protection provided by single mast to two masts as well as from single shield wire to double shielding wires. The outcomes of these four equations will be compared.展开更多
Photocatalytic methane(CH_(4))production wherein CO_(2)is reduced to CH_(4) by utilizing solar radiation energy is gaining research and industrial focus because of its environmental-friendly notion.It offers twofold a...Photocatalytic methane(CH_(4))production wherein CO_(2)is reduced to CH_(4) by utilizing solar radiation energy is gaining research and industrial focus because of its environmental-friendly notion.It offers twofold advantages:reduction in CO_(2)emission and production of artificial natural gas(methane)at the same time.In this paper,comparative energy,economic and environmental assessment of such photocatalytic methane production has been carried out between Japan and Malaysian conditions.Assumptions on the photocatalytic methane production plant and estimation of energy production,CO_(2)emission reduction,and economic indicators are made based on previous research and existing technologies.Energy analysis shows that Malaysia has a higher potential for energy production and CO_(2)emission reduction than Japan.Economic analysis reveals that the feasible reaction efficiencies of the plant in Japan and Malaysia are 8%.The slightly higher conversion efficiency in Malaysia is due to the energy price and CO_(2)tax.For the implementation of the photocatalytic methane production plant,the high energy price and CO_(2)tax will work as a driving force.展开更多
This paper proposes a grid-tied photovoltaic(PV)inverter capable of low-voltage ride through(LVRT), reactive power support, and islanding protection. Unlike other LVRT inverters, the proposed inverter is independent o...This paper proposes a grid-tied photovoltaic(PV)inverter capable of low-voltage ride through(LVRT), reactive power support, and islanding protection. Unlike other LVRT inverters, the proposed inverter is independent of sag severity while maintaining the maximum power-point tracking(MPPT)under normal and faulty conditions. The addition of an energy storage buffer stage mitigates the DC-link voltage surge during sags. At the same time, the inverter injects the reactive power during back-to-back sags of variable depths. The control system of the inverter generates the appropriate reference signals for normal, LVRT, and anti-islanding modes while the MPPT continues running. The salient features of the proposed inverter are:(1) active power injection under normal grid conditions;(2)sag-depth independent LVRT with reactive power support;(3)no DC-link fluctuations;(4) continuous MPPT mode;and(5) simultaneous LVRT and anti-islanding support during a grid outage. The inverter demonstrates an uninterrupted operation and seamless transition between various operating modes. Simulations and the experimental prototype have been implemented to validate the efficacy of the proposed PV inverter.展开更多
Photovoltaic(PV)system’s performance is significantly affected by its orientation and tilt angle.Experimental investigation(indoor and outdoor)has been carried out to trace the variation in PV performance and electri...Photovoltaic(PV)system’s performance is significantly affected by its orientation and tilt angle.Experimental investigation(indoor and outdoor)has been carried out to trace the variation in PV performance and electrical parameters at varying tilt angles in Malaysian conditions.There were two experimental modus:1)varying module tilt under constant irradiation level,2)varying irradiation intensity at the optimum tilt set up.For the former scheme,the irradiation level was maintained at 750 W/m^(2),and for the later arrangement,the module tilt angle was varied from 0 o to 80 o by means of a single-axis tracker.Results show that under constant irradiation of 750 W/m^(2),every 5 o increase in tilt angle causes a power drop of 2.09 W at indoor and 3.45 W at outdoor.In contrast,for the same condition,efficiency decreases by 0.54%for indoor case and by 0.76%at outdoor.On the other hand,for every 100 W/m^(2)increase in irradiation,solar cell temperature rises by 7.52℃at indoor and by 5.67℃at outdoor.As of module electrical parameters,open-circuit voltage,short-circuit current,maximum power point voltage and maximum power point current drops substantially with increasing tilt angle,whereas fill factor drops rather gradually.Outdoor experimental investigation confirms that the optimum tilt angle at Malaysian conditions is 15 o and orienting a PV module this angle will maximize the sun’s energy captured and thereby enhance its performance.展开更多
There are many factors that have a major influence on reducing the energy expenditure in building sector.This research aims at qualitative and quantitative assessment of those factors such as double glazed windows,ver...There are many factors that have a major influence on reducing the energy expenditure in building sector.This research aims at qualitative and quantitative assessment of those factors such as double glazed windows,ver-tical greenery systems(VGS),integrating of semi-transparent photovoltaic device with architectural design of buildings,energy saving by using heat reflecting coating,passive climate control methods,energy saving by shading,building energy performance enhancement by using optimisation technique,double skin green facade,etc.through a holistic and thematic approach.Amongst the aforesaid techniques,VGS is found the most reliable,efficient and sustainable solution.Attractive VGS can improve the urban environment,increase biodiversity,mit-igate pollution also results economic benefit of the buildings as like as energy savings and decreasing surface temperature.Four fundamental energy saving methods are used in VGS which are considered as passive energy saving mechanism.Firstly,interception of solar radiation due to the shadow risen by the vegetation;secondly,vegetation also provides thermal insulation;thirdly,plants evapotranspiration helps for evaporative cooling of building;finally,building blockage makes a variation of wind effect on building.The peak cooling load of ivy coated green building wall has been reduced by 28%.If a VGS is installed without windows and building fac-ing on west,east,south and north correspondingly,the reduction in the cooling load capacity of the building is observed to be up to 20,18,8 and 5%,respectively.Very high thermally resistive glazed areas on building envelope can be secured via thin film PV glazing and vacuum glazing products with an average U-value of 1.1 and 0.4 W/m 2 K,respectively.Energy use policies are also helpful to improve energy consumption scenario of buildings.For developing more energy-efficient,sustainable and eco-friendly buildings,these techniques might be helpful for the building designers and architects.展开更多
During this decade,graphene which is a thin layer of carbon material along at ease with synthesis and functionalization has become a hot topic of research owing to excellent mechanical strength,very good current densi...During this decade,graphene which is a thin layer of carbon material along at ease with synthesis and functionalization has become a hot topic of research owing to excellent mechanical strength,very good current density,high thermal conductivity,superior electrical conductivity,large surface area,and good electron mobility.The research on graphene has exponentially accelerated specially when Geim and Novoselov developed and analyzed graphene.On this basis,for industrial application,researchers are exploring different techniques to produce high-quality graphene.Therefore,reviewed in this article is a brief introduction to graphene and its derivatives along with some of the methods developed to synthesize graphene and its prospective applications in both research and industry.In this work,recent advances on applications of graphene in various fields such as sensors,energy storage,energy harvesting,high-speed optoelectronics,supercapacitors,touch-based flexible screens,and organic light emitting diode displays have been summarized.展开更多
An islanding operation of a distribution network is a topic of interest due to the significant penetration of distributed generation(DG) in a power system network. However, controlling the frequency of an islanded dis...An islanding operation of a distribution network is a topic of interest due to the significant penetration of distributed generation(DG) in a power system network. However, controlling the frequency of an islanded distribution system remains an unresolved issue, especially when the load exceeds the generation. This paper presents a new technique for a successful islanding operation of a distribution network connected with multiple mini hydro based DGs. The proposed technique is based on three main parts. The first part uses an islanding detection technique to detect the islanding event correctly. The second part consists of a power imbalance estimation module(PIEM), which determines the power imbalance between the generation and load demand. The third part consists of a load shedding controller, which receives the power imbalance value and performs load shedding according to load priority. The proposed technique is validated on an 11 k V existing Malaysia distribution network. The simulation results show that the proposed technique is effective in performing a successful islanding operation by shedding a significant number of loads.展开更多
The ever-present demand for energy from various application in industrial and domestic processes has led to the consumption of fossil fuel at a rapid rate with adverse effect due to global warming.This study focuses o...The ever-present demand for energy from various application in industrial and domestic processes has led to the consumption of fossil fuel at a rapid rate with adverse effect due to global warming.This study focuses on the thermal energy storage aspect intended for medium temperature applications.A novel composite A70 and PANI was prepared and characterized.The study investigates the composites thermophysical and optical properties.Differential Scanning Calorimetry and Transient Hot Bridge measured thermal storage capacity and thermal conductivity of the composite,respectively.The heat storage capacity of the composite remained stable within 4%whereas a highest rise of 11.96%in thermal conductivity was measured.The composites thermal,chemical,and physical stability were analysed from Thermogravimetric Analyser,Fourier Infrared Transform,and Scanning Electron Microscope,respectively.The composites were thermally stable up to a temperature of 250°C.No chemical reaction occurred between the nanomaterial and base PCM matrix.The microscopic visuals did not show any considerable change in the microscopic structure of the material.In the case of optical properties,the composites showed significant reduction in transmittance of solar spectrum with respect to pure A70.The maximum decrement in transmission was around~89%compared to A70.As the composite prepared were thermally stable till 250°C,hence may be utilized for solar thermal and low concentrated photovoltaic application but not limited to these.展开更多
基金financially supported by the Ministry of Higher Education through the Fundamental Research Grant Scheme (FRGS/1/2022/STG05/UM/01/2) awarded to Ramesh T Subramaniamby Technology Development Fund 1 (TeD1)from the Ministry of Science,Technology,and Innovation (MOSTI),Malaysia (MOSTI002-2021TED1)supported by the Key Research Program of Yichang City(2023KYPT0303)
文摘Sodium-ion batteries (SIBs) have great potential to be the next major energy storage devices due to their obvious advantages and developing advanced electrodes and electrolytes is urgently necessary to promote its future industrialization.However,hard carbon as a state-of-the-art anode of SIBs still suffers from the low initial Coulomb efficiency and unsatisfactory rate capability,which could be improved by forming desirable solid electrolyte interphases (SEI) to some extent.Indeed,the chemistry and morphology of these interfacial layers are fundamental parameters affecting the overall battery operation,and optimizing the electrolyte to dictate the quality of SEI on hard carbon is a key strategy.Hence,this review summarizes the recent research on SEI design by electrolyte manipulation from solvents,salts,and additives.It also presents some potential mechanisms of SEI formation in various electrolyte systems.Besides,the current advanced characterization techniques for electrolyte and SEI structure analyses have been comprehensively discussed.Lastly,current challenges and future perspectives of SEI formation on hard carbon anode for SIBs are provided from the viewpoints of its compositions,evolution processes,structures,and characterization techniques,which will promote SEI efficient manipulation and improve the performance of hard carbon,and further contribute to the development of SIBs.
基金Project (RG039-09AET) supported by University of Malaya, Malaysia
文摘A novel shrouded wind-solar hybrid renewable energy and rain water harvester with an omni-directional-guide-vane(ODGV) for urban high-rise application is introduced.The ODGV surrounds the vertical axis wind turbine(VAWT) and enhances the VAWT performance by increasing the on-coming wind speed and guiding it to an optimum flow angle before it interacts with the rotor blades.An ODGV scaled model was built and tested in the laboratory.The experimental results show that the rotational speed of the VAWT increases by about 2 times.Simulations show that the installation of the ODGV increases the torque output of a single-bladed VAWT by 206% for tip speed ratio of 0.4.The result also reveals that higher positive torque can be achieved when the blade tangential force at all radial positions is optimized.In conclusion,the ODGV improves the power output of a VAWT and this integrated design promotes the installation of wind energy systems in urban areas.
文摘Photovoltaic(PV)systems are adversely affected by partial shading and non-uniform conditions.Meanwhile,the addition of a bypass shunt diode to each PV module prevents hotspots.It also produces numerous peaks in the PV array’s power-voltage characteristics,thereby trapping conventional maximum power point tracking(MPPT)methods in local peaks.Swarm optimization approaches can be used to address this issue.However,these strategies have an unreasonably long convergence time.The Grey Wolf Optimizer(GWO)is a fast and more dependable optimization algorithm.This renders it a good option for MPPT of PV systems operating in varying partial shading.The conventional GWO method involves a long conversion time,large steady-state oscillations,and a high failure rate.This work attempts to address these issues by combining Cuckoo Search(CS)with the GWO algorithm to improve the MPPT performance.The results of this approach are compared with those of conventional MPPT according to GWO and MPPT methods based on perturb and observe(P&O).A comparative analysis reveals that under non-uniform operating conditions,the hybrid GWO CS(GWOCS)approach presented in this article outperforms the GWO and P&O approaches.
基金Supported by the Research Grants of the Research Council of Malaya
文摘A two-phase dynamic model, describing gas phase propylene polymerization in a fluidized bed reactor, was used to explore the dynamic behavior and process control of the polypropylene production rate and reactor temperature. The open loop analysis revealed the nonlinear behavior of the polypropylene fluidized bed reactor, jus- tifying the use of an advanced control algorithm for efficient control of the process variables. In this case, a central- ized model predictive control （MPC） technique was implemented to control the polypropylene production rate and reactor temperature by manipulating the catalyst feed rate and cooling water flow rate respectively. The corre- sponding MPC controller was able to track changes in the setpoint smoothly for the reactor temperature and pro- duction rate while the setpoint tracking of the conventional proportional-integral （PI） controller was oscillatory with overshoots and obvious interaction between the reactor temperature and production rate loops. The MPC was able to produce controller moves which not only were well within the specified input constraints for both control vari- ables, but also non-aggressive and sufficiently smooth for practical implementations. Furthermore, the closed loop dynamic simulations indicated that the speed of rejecting the process disturbances for the MPC controller were also acceotable for both controlled variables.
文摘Malaysia is one of the many countries that experience high lightning related activities. In fact, according to Malaysian Meteorological Department the Ground Flash Density (GFD) in Malaysia, it is rated at the fifth place in the ten most lightning cities of the world, with a high keraunic level, which is 240 thunderstorm days per year, and in other words, a Ground Flash Density (GFD) of 48.3 flashes per square kilometer per year. In the power systems, high keraunic level would contribute to high possibility of power interruptions such as disruption, degradation, damage and downtime. These outages would ultimately lead to revenue losses and reduction of network reliability. These lightning related interruptions may be in terms of direct lightning strikes to the lines or to the equipments in the substation. By the use of Mat Lab GUI (Graphic Users Interface), this study presents a simple computer program which uses the electro-geometric model (EGM) for the designing of substation shielding systems. The EGM uses the concept where the protection zone of a lightning system lies within the radius where the upward channel initiates and propagates through the air terminal to meet the downward leader. This interception point is called “the point of discrimination” and is where the downward leader decides its final jump. The distance at which the last jump occurs is known as the striking distance. With the use of the striking distance and the mathematical equations developed by Young, Brown-Whitehead, IEEE-1992 (IEEE T&D Committee Equations) and IEEE-1995 (IEEE Substations Committee Equations). This project aimed to investigate, understand and analyse the substation protection by means of masts and shield wires. The analysis is extended to account for lightning protection provided by single mast to two masts as well as from single shield wire to double shielding wires. The outcomes of these four equations will be compared.
基金the support from the Kyoto University and University of Malaya double degree programme to carry out this research
文摘Photocatalytic methane(CH_(4))production wherein CO_(2)is reduced to CH_(4) by utilizing solar radiation energy is gaining research and industrial focus because of its environmental-friendly notion.It offers twofold advantages:reduction in CO_(2)emission and production of artificial natural gas(methane)at the same time.In this paper,comparative energy,economic and environmental assessment of such photocatalytic methane production has been carried out between Japan and Malaysian conditions.Assumptions on the photocatalytic methane production plant and estimation of energy production,CO_(2)emission reduction,and economic indicators are made based on previous research and existing technologies.Energy analysis shows that Malaysia has a higher potential for energy production and CO_(2)emission reduction than Japan.Economic analysis reveals that the feasible reaction efficiencies of the plant in Japan and Malaysia are 8%.The slightly higher conversion efficiency in Malaysia is due to the energy price and CO_(2)tax.For the implementation of the photocatalytic methane production plant,the high energy price and CO_(2)tax will work as a driving force.
基金supported by the Program Research Grant UMPEDAC-2020(No. MOHE HICOE-UMPEDAC)the Ministry of Education Malaysia (No.RU003-2020, RU002-2021)the University of Malaya。
文摘This paper proposes a grid-tied photovoltaic(PV)inverter capable of low-voltage ride through(LVRT), reactive power support, and islanding protection. Unlike other LVRT inverters, the proposed inverter is independent of sag severity while maintaining the maximum power-point tracking(MPPT)under normal and faulty conditions. The addition of an energy storage buffer stage mitigates the DC-link voltage surge during sags. At the same time, the inverter injects the reactive power during back-to-back sags of variable depths. The control system of the inverter generates the appropriate reference signals for normal, LVRT, and anti-islanding modes while the MPPT continues running. The salient features of the proposed inverter are:(1) active power injection under normal grid conditions;(2)sag-depth independent LVRT with reactive power support;(3)no DC-link fluctuations;(4) continuous MPPT mode;and(5) simultaneous LVRT and anti-islanding support during a grid outage. The inverter demonstrates an uninterrupted operation and seamless transition between various operating modes. Simulations and the experimental prototype have been implemented to validate the efficacy of the proposed PV inverter.
基金The authors would like to acknowledge the financial support from University of Malaya,Impact Oriented Interdisciplinary Research Grant(Project:IIRG015B-2019)to carry out this research.
文摘Photovoltaic(PV)system’s performance is significantly affected by its orientation and tilt angle.Experimental investigation(indoor and outdoor)has been carried out to trace the variation in PV performance and electrical parameters at varying tilt angles in Malaysian conditions.There were two experimental modus:1)varying module tilt under constant irradiation level,2)varying irradiation intensity at the optimum tilt set up.For the former scheme,the irradiation level was maintained at 750 W/m^(2),and for the later arrangement,the module tilt angle was varied from 0 o to 80 o by means of a single-axis tracker.Results show that under constant irradiation of 750 W/m^(2),every 5 o increase in tilt angle causes a power drop of 2.09 W at indoor and 3.45 W at outdoor.In contrast,for the same condition,efficiency decreases by 0.54%for indoor case and by 0.76%at outdoor.On the other hand,for every 100 W/m^(2)increase in irradiation,solar cell temperature rises by 7.52℃at indoor and by 5.67℃at outdoor.As of module electrical parameters,open-circuit voltage,short-circuit current,maximum power point voltage and maximum power point current drops substantially with increasing tilt angle,whereas fill factor drops rather gradually.Outdoor experimental investigation confirms that the optimum tilt angle at Malaysian conditions is 15 o and orienting a PV module this angle will maximize the sun’s energy captured and thereby enhance its performance.
基金Authors would like to acknowledge the financial support from Uni-versity of Malaya,Impact orientated Interdisciplinary Research Grant(Project:IIRG015B-2019)to carry out this research.
文摘There are many factors that have a major influence on reducing the energy expenditure in building sector.This research aims at qualitative and quantitative assessment of those factors such as double glazed windows,ver-tical greenery systems(VGS),integrating of semi-transparent photovoltaic device with architectural design of buildings,energy saving by using heat reflecting coating,passive climate control methods,energy saving by shading,building energy performance enhancement by using optimisation technique,double skin green facade,etc.through a holistic and thematic approach.Amongst the aforesaid techniques,VGS is found the most reliable,efficient and sustainable solution.Attractive VGS can improve the urban environment,increase biodiversity,mit-igate pollution also results economic benefit of the buildings as like as energy savings and decreasing surface temperature.Four fundamental energy saving methods are used in VGS which are considered as passive energy saving mechanism.Firstly,interception of solar radiation due to the shadow risen by the vegetation;secondly,vegetation also provides thermal insulation;thirdly,plants evapotranspiration helps for evaporative cooling of building;finally,building blockage makes a variation of wind effect on building.The peak cooling load of ivy coated green building wall has been reduced by 28%.If a VGS is installed without windows and building fac-ing on west,east,south and north correspondingly,the reduction in the cooling load capacity of the building is observed to be up to 20,18,8 and 5%,respectively.Very high thermally resistive glazed areas on building envelope can be secured via thin film PV glazing and vacuum glazing products with an average U-value of 1.1 and 0.4 W/m 2 K,respectively.Energy use policies are also helpful to improve energy consumption scenario of buildings.For developing more energy-efficient,sustainable and eco-friendly buildings,these techniques might be helpful for the building designers and architects.
基金providing the research facilitiesandIIRG grantIIRG007C-19IISS and SATU Joint grant ST031-2021.
文摘During this decade,graphene which is a thin layer of carbon material along at ease with synthesis and functionalization has become a hot topic of research owing to excellent mechanical strength,very good current density,high thermal conductivity,superior electrical conductivity,large surface area,and good electron mobility.The research on graphene has exponentially accelerated specially when Geim and Novoselov developed and analyzed graphene.On this basis,for industrial application,researchers are exploring different techniques to produce high-quality graphene.Therefore,reviewed in this article is a brief introduction to graphene and its derivatives along with some of the methods developed to synthesize graphene and its prospective applications in both research and industry.In this work,recent advances on applications of graphene in various fields such as sensors,energy storage,energy harvesting,high-speed optoelectronics,supercapacitors,touch-based flexible screens,and organic light emitting diode displays have been summarized.
基金supported by the Ministry of Higher Education,Malaysia under Research Acculturation Collaborative Effort(Nos.600-RMI RACE 16/6/2 and CR003-2014)E-Science Fund Research Gran(No.SF005-2013)the University of Malaya and Quaid-e-Awam University of Engineering Science&Technology Nawabshah,Sindh Pakistan
文摘An islanding operation of a distribution network is a topic of interest due to the significant penetration of distributed generation(DG) in a power system network. However, controlling the frequency of an islanded distribution system remains an unresolved issue, especially when the load exceeds the generation. This paper presents a new technique for a successful islanding operation of a distribution network connected with multiple mini hydro based DGs. The proposed technique is based on three main parts. The first part uses an islanding detection technique to detect the islanding event correctly. The second part consists of a power imbalance estimation module(PIEM), which determines the power imbalance between the generation and load demand. The third part consists of a load shedding controller, which receives the power imbalance value and performs load shedding according to load priority. The proposed technique is validated on an 11 k V existing Malaysia distribution network. The simulation results show that the proposed technique is effective in performing a successful islanding operation by shedding a significant number of loads.
基金One of the author(A K Pandey)duly acknowledges the financial assistance through Sunway University collaborative research fund:MRU 2019(STR-RMF-MRU-004-2019)for carrying out this researchThe authors thank the technical and financial assistance of UM Power Energy Dedicated Advanced center(UMPEDAC)and the Higher Institution center of Excellence(HICoE)Program Research Grant,UMPEDAC-2018(MOHE HICOE-UMPEDAC)+1 种基金Ministry of Education MalaysiaTOP100UMPEDAC and RU012-2019,University of Malaya.
文摘The ever-present demand for energy from various application in industrial and domestic processes has led to the consumption of fossil fuel at a rapid rate with adverse effect due to global warming.This study focuses on the thermal energy storage aspect intended for medium temperature applications.A novel composite A70 and PANI was prepared and characterized.The study investigates the composites thermophysical and optical properties.Differential Scanning Calorimetry and Transient Hot Bridge measured thermal storage capacity and thermal conductivity of the composite,respectively.The heat storage capacity of the composite remained stable within 4%whereas a highest rise of 11.96%in thermal conductivity was measured.The composites thermal,chemical,and physical stability were analysed from Thermogravimetric Analyser,Fourier Infrared Transform,and Scanning Electron Microscope,respectively.The composites were thermally stable up to a temperature of 250°C.No chemical reaction occurred between the nanomaterial and base PCM matrix.The microscopic visuals did not show any considerable change in the microscopic structure of the material.In the case of optical properties,the composites showed significant reduction in transmittance of solar spectrum with respect to pure A70.The maximum decrement in transmission was around~89%compared to A70.As the composite prepared were thermally stable till 250°C,hence may be utilized for solar thermal and low concentrated photovoltaic application but not limited to these.
