... 68 7 Local Non-Destructive Status Determination for Concentric Wire Shield Cables and Cables ... more ... 68 7 Local Non-Destructive Status Determination for Concentric Wire Shield Cables and Cables Sheathed in Lead James M. Feldman Nicholas Reinhardt Thomas Walsh ... Joshua Horwitz, Kate Morris, George Vrablik and John Rudy Accelerated Systems, Inc., Beverly, MA 01915 ...
Journal of Geophysical Research: Atmospheres, 2017
Rapid urbanization of cities has greatly modified the thermal and dynamic profile in the urban bo... more Rapid urbanization of cities has greatly modified the thermal and dynamic profile in the urban boundary layer. This paper attempts to study the interaction of urban heating and the local topographic‐induced flow circulation for a tropical coastal city, Greater Kuala Lumpur, in Malaysia. The role of sea‐and‐valley‐breeze‐orientated synoptic flow (SBOS) on the interaction is determined by comparing two intermonsoon periods. A state‐of‐the‐art numerical model, Advanced Research Weather Research and Forecasting model, is used to identify the influence of urbanization through modification of urban surfaces. The model reasonably reproduces the vertical sounding data and near‐surface weather parameters. The diurnal urban heating pattern is attributed to three predominant factors: (i) weak under calm and clear‐sky condition (morning heating), (ii) weak under larger atmospheric moisture content (late afternoon convection), and (iii) largest (1.4°C) due to differential cooling rate of urban a...
The modification of land use is known to be a major climate change driver to the local warming an... more The modification of land use is known to be a major climate change driver to the local warming and air quality in cities. Despite the reduction of NO x over the years, the Selangor state has captured a higher level of O 3 in year 2011. The measurement result has shown that the surge in O 3 level was attributed to the reduction of NO x /NMHC ratio. This paper hence attempted to identify the role of land use change from 1999 to 2011 on the ground ozone air quality in the tropical urban conurbation, Greater Kuala Lumpur (GKL), Selangor, Malaysia. With the state-of-the-art chemical weather prediction tool, WRF-Chem, the external synoptic factors and emission inventory were controlled when comparing the chronological land use changes. The results showed that the urban-induced temperature and wind bias in the tropical region has induced stronger wind to disperse the NO x and carries the TVOC from the suburban to the downwind urban region. The reduction of NO x /TVOC has gradually shifted towards the optimum O 3 formation regime in 2011. The formation of highly concentrated ozone becomes more sensitive to the increment of TVOC as the NO x level reduces in the urban. This highlights the essential involvement of TVOC in the ozone formation in lieu of the NO x reduction in the tropical city, a region with growing emitter of reactive biogenic ozone precursors.
One significant effect of urbanization is the modification of natural surfaces, local environment... more One significant effect of urbanization is the modification of natural surfaces, local environment, and thermal comfort. Farmland and agricultural land in Klang Valley conurbation, Malaysia have been replaced with engineered surfaces and infrastructures to accommodate the rapid population growth witnessed in the past decades. To understand the current environmental conditions of the conurbation, numerical Weather Research and Forecasting (WRF) model coupled to the Urban Canopy Model (UCM) was used. A model evaluation conducted against a network of observations showed an overall good performance of the model in predicting near-surface meteorological parameters. Also, an examination of spatiotemporal variability of urban parameters revealed a diurnal dependence of human physiological thermal conditions on urbanization level. A maximum urban heat island intensity (UHII) of~2.64 C was observed. In an effort to investigate the effect of urbanization level on the extremities of urban climatic conditions, two different experiments with varying urban/vegetation fractions were further simulated. The latter results indicate that urbanization level has a significant effect on the extremities of urban climatological parameters and spatial extent of the induced impacts. Furthermore, the effect of urbanization level on the mean urban outdoor thermal discomfort (UOTD) level was significant (with an increase of 0.7 C, 0.64 C and 0.04 observed) for temperature humidity index (THI), effective temperature index (ETI) and relative strain index (RSI), respectively. However, a non-significant (at 95% level) effect of urbanization level on the extremities of UOTD indices was observed.
observed on the spatiotemporal variation in meteorology of the area; especially along the coastli... more observed on the spatiotemporal variation in meteorology of the area; especially along the coastline bordering Strait of Malacca (by sea-land breezes) and the Titiwangsa mountain range (by mountain-valley breezes).
The garden city concept was adopted in the development of a new tropical city, Putrajaya, aimed a... more The garden city concept was adopted in the development of a new tropical city, Putrajaya, aimed at mitigating the effect of urban thermal modification associated with urbanisation, such as urban heat island (UHI). WRF/Noah/UCM coupled system was used to estimate the urban environment over the area and the individual thermal contributions of natural land use classes (vegetation and waterbody). A control experiment including all land use types describing the urban conditions of Putrajaya city agreed well with the observations in the region. A series of experiments was then conducted, in which vegetation and waterbody were successively replaced with an urban land use type, providing the basis for an assessment of their respective effect on urban thermal mitigation. Surface energy components, 2-m air temperature (T2m) and mixing ratio (Q2m), relative humidity (RH) and UHI intensity (UHII) showed variations for each land use class. Overall, an increase in urban surfaces caused a corresponding increase in the thermal conditions of the city. Conversely, waterbody and vegetation induced a daily reduction of 0.14 and 0.39 °C of T2m, respectively. RH, UHI and T2m also showed variations with urban fractions. A thermal reduction effect of vegetation is visible during mornings and nights, while that of water is minimally shown during daytime. However, during nights and mornings, canopy layer thermal conditions above waterbody remain relatively high, with a rather undesirable effect on the surrounding microclimate, because of its high heat capacity and thermal inertia.
This study aims to identify the vertical transport mechanisms that uplifted the forest fire emiss... more This study aims to identify the vertical transport mechanisms that uplifted the forest fire emissions from Sumatra to the upper troposphere during the June 2013 haze crisis. WRF-Chem is used to simulate the formation and transport of biomass-burning haze during the study period of 18 th to 26 th June 2013. The South-Southeast Asian synoptic weather patterns and their effects on the transport of biomass-burning emissions from Sumatra to Peninsular Malaysia were studied computationally to explain the phenomenon. Results show that PM 10 emissions were lifted to 200 hPa height (approximately 12 km) over the Strait of Malacca on 24 th June. The two identified vertical transport mechanisms confirmed a previously conjectured convergence over the Strait of Malacca and orographic lifting over Peninsular Malaysia. These mechanisms were able to uplift the biomass-burning emissions to the upper troposphere and this could have significant long-range transport and global climatic effects.
The urban boundary layer (UBL) is the internal advection layer of atmosphere above urban region w... more The urban boundary layer (UBL) is the internal advection layer of atmosphere above urban region which determines the exchanges of momentum, water and other atmospheric constituents between the urban land surface and the free troposphere. This paper tested the performance of three planetary boundary layer (PBL) physics schemes of Weather Research and Forecast (WRF) software to ensure the appropriate representation of vertical structure of UBL in Greater Kuala Lumpur (GKL). Comparison was conducted on the performance of respective PBL schemes to generate vertical and near-surface weather profile and rainfall. Mellor-Yamada- Janjíc (MYJ) local PBL scheme coupled with Eta MM5 surface layer scheme was found to predict the near-surface temperature and wind profile and mixing height better than the nonlocal schemes during the intermonsoonal period with least influences of the synoptic background weather.
The Weather Research and Forecasting (WRF) mesoscale model is used to study the effect of urban h... more The Weather Research and Forecasting (WRF) mesoscale model is used to study the effect of urban heating on the local climate of the largest urban agglomeration of Malaysia, Greater Kuala Lumpur (GKL) during a period of weak synoptic forcing. Urbanization has induced a modelled daily mean urban heat island (UHI) intensity of 0.9°C with a more severe heating (1.9°C) at night. The diurnal wind field of GKL is greatly affected by the circulation of land/sea breeze. The immense heat generated in the city accelerates the moisture-bearing sea breeze during the day and the induced vertical lifting simultaneously creates a conducive environment for convective precipitation on the upwind region. The urban heating effect and surface roughness weakens the evening flow circulations in the region and potentially inhibits dispersion of heat and atmospheric pollutants. Simulation of UHI phenomenon is especially sensitive to the characterization of urban grids through sensitivity evaluation of numerous land use maps and urban canopy model (UCM) settings. When compared to observations, the WRF model best captures the urban heating phenomenon with updated land use map and calibrated single layer UCM, while the simple bulk UCM setting performs better than the default complex single layer UCM.
The administrative capital of Malaysia, Putrajaya, is one of those cities built on the garden-cit... more The administrative capital of Malaysia, Putrajaya, is one of those cities built on the garden-city concept, however, few studies have been devoted to confirm the validity of the concept. Numerical mesoscale Weather Research and Forecasting (WRF) Model was coupled with Noah land surface model and a single layer urban canopy model (UCM) to investigate the existence and distribution of UHI, and the behaviour of urban canopy layer (2-m) temperature of Putrajaya city. Suitability of the model WRF employed in studying UHI phenomenon in the tropical city of Putrajaya, Malaysia was determined. Precincts in Putrajaya city were classified into local climate zones (LCZs) and the contribution of urban fabrics on the spatial and temporal variations of UHI was also investigated. Results of the model were verified with in situ studies of the area, and observational data from Alam Sekitar Malaysia Sdn Bhd (ASMA). Comparison with ASMA observational and in situ data reveals a satisfactory performance of the model. UHI intensity of Putrajaya exhibits a diurnal profile; increasing during the night to a peak value and then diminishing in the morning with a negligible value during midday. During the night hours, the UHII ranges from 1.9 • C to 3.1 • C in some of the precincts (LCZs) considered. Overall, average daily intensity of 0.79 • C heating was noted in Putrajaya for the study duration. The overall effect of urbanized LCZs heating of Putrajaya was normalized by the total amount of area reserved for vegetation.
This study presents first comprehensive thermochemical analysis of Bambara groundnut shell. Pyrol... more This study presents first comprehensive thermochemical analysis of Bambara groundnut shell. Pyrolysis characteristics was examined under non-isothermal degradation in nitrogen atmosphere at different heating rates (10, 15 and 20 C/min) using single-step global model kinetic model. The single-step global model average apparent activation energy was found to be 142.64 ± 5.7 kJ/mol. Pyrolysis was conducted in a fixed bed reactor. Effects of pyrolysis temperature (450e750 C), heating rate (20e50 C/min) and nitrogen flow rate (5e25 L/min) were investigated collectively. The process variables were optimized using response surface methodology with central composite design. Optimum bio-oil yield of 36.49 wt% was recorded at 600 C, 50 C/min and 11 L/min. The bio-oil, bio-char and non-condensable gas collected were comprehensively characterised. Energy analysis of the products was also evaluated. This study revealed that Bambara groundnut shell, a residue from food crop, is a potential source of energy precursors for development of a sustainable bioenergy system and biomaterials.
Urbanisation is associated with physical modifications of land surfaces and climate of a given ar... more Urbanisation is associated with physical modifications of land surfaces and climate of a given area. Studies of urbanisation effect on urban climate for Klang Valley region is below par. This research aims to bridge the gap by using a coupled Weather Research and Forecasting (WRF) model with the NOAH Land Surface Model (NOAH) and Urban Canopy Model (UCM)-WRF/NOAH/UCM to investigate the urban climatology of Klang Valley and the urbanisation of Putrajaya over a decade. In addition, evaluation of the garden city concept adopted in the development of Putrajaya city is also conducted. The model is first validated against a network of meteorological observations in the region to determine its suitability for urban climate investigations. Climatological variables (near-surface temperature, relative humidity, and wind speed) along with land use and land cover (LULC) changes; planetary boundary layer height (PBLH), and urban heat/cool islands (UHI/UCI) of the area are also investigated. The model evaluation shows good performance over the region. LULC changes demonstrates strong influence in thermal climatology variations. A mean maximum UHI intensity of ~4.2 ºC was observed in the urban canopy-layer of the Klang Valley. Results reveal that urbanisation of Putrajaya leads to 2-m temperature increase at the rate of ~1.66 ºC per decade, with the area experiencing a mean UHI intensity of ~2.1 ºC per day. Other climatological variables vary accordingly with the urbanisation processes. Evaluation of the garden city concept indicates that the adopted concept causes a reduction in 2-m air temperature of the Putrajaya area, amounting to ~0.53 ºC per day; with vegetation contributing more (~0.39 ºC) to the daily reduction relative to water bodies (~0.14 ºC). Location of the city in the tropics accustomed with high intensity of daily solar radiation masked the cooling potentials of the concept to some extent.
International Journal of Simulation and Process Modelling, 2017
The application of gears, especially spur gear, is widely available in most engineering applicati... more The application of gears, especially spur gear, is widely available in most engineering applications. Especially for high module steel spur gear, it is used extensively in heavy machineries such as cranes and metal crushers. Therefore, it is crucial to avoid catastrophic damage to gears by understanding the crack behaviour. Provided the crack does not propagate into the rim, only minor accidents are likely to happen or else catastrophe may be expected again. Therefore, the study of crack behaviour on stress intensity factor (SIF) with different magnitude of moment was conducted. This study implemented the application of extended finite element method (XFEM) in ABAQUS to overcome the limitations of a conventional method, the finite element method (FEM). The need of re-meshing was avoided in this simulation. The crack propagation pathways were visualised using the 'STATUSXFEM'.
British Journal of Environment and Climate Change, Jan 10, 2015
Despite increased interest on the urban heat island (UHI) phenomenon, there are limited UHI studi... more Despite increased interest on the urban heat island (UHI) phenomenon, there are limited UHI studies on cities built using the green-city concept of Sir Ebenezer Howard [1]. The administrative capital of Malaysia, Putrajaya is one of such cities built using the green-city concept. The objective of this study was to confirm the effectiveness of the green city concept using the National Centre for Atmospheric Research (NCAR) numerical technique. Numerical mesoscale Weather Research and Forecasting (WRF) Model was coupled with Noah land surface model and a single layer urban canopy model (UCM) to investigate the existence and distribution of UHI, and the behavior of urban canopy layer (2-m) temperature of Putrajaya city. Few studies have been conducted using the NCAR numerical technique (WRF) to explore Malaysian climatology. Suitability of the model employed in studying UHI phenomenon of Putrajaya city was determined using in-situ study of the area, and observational data from AlamSekitar Malaysia SdnBhd (ASMA). Contribution of urban fabrics on the spatial and temporal variations of UHI was also investigated. Comparison with ASMA and in-situ data revealed a satisfactory performance of the model.UHI intensity (UHII) of Putrajaya exhibits a diurnal profile; increasing during the night to a peak value and then diminishing towards morning with a negligible value in the midday. In the night time, the UHII ranges from Original Research Article
One of the worst haze events to ever hit Peninsular Malaysia occurred in June 2013 due to smoke f... more One of the worst haze events to ever hit Peninsular Malaysia occurred in June 2013 due to smoke from Riau, Central Sumatra. While biomass-burning in the region is common, the early occurrence of a haze episode of this magnitude was uncharacteristic of the seasonality of extreme fire events, which usually occur between August and October in the Maritime Continent (MC). This study aims to investigate the phenomenology of the June 2013 haze event and its underlying meteorological forcing agents. The aerosol and meteorological environment during the event is examined using the Moderate Resolution Imaging Spectroradiometer (MODIS) active fire hotspot detections and aerosol optical thickness retrievals, satellite-based precipitation retrievals, and meteorological indices. These datasets are then supported by a WRF-Chem simulation to provide a comprehensive picture of the event's meteorology and aerosol transport phenomenology. While extreme fire events are more characteristic of El Nino years, the MODIS fire count over the MC in June for the years 2001-2015 was highest in 2013 when neutral El Nino/Southern Oscillation (ENSO) conditions prevailed. Although, the mean daily precipitation for June 2013 was below average for June 2003-2015. An early active tropical cyclone (TC) season occurred in 2013, and results show that the combined induced subsidence and flow enhancement due to TC Bebinca and the dry phases of a strong Madden-Julian Oscillation (MJO) event contributed to the event intensification. Results also show that Bebinca induced a decrease in surface relative humidity of at least 10% over Riau, where fire hotspots were concentrated.
Isoprene (C5H8) plays an important role in the formation of surface ozone (O3) and the secondary ... more Isoprene (C5H8) plays an important role in the formation of surface ozone (O3) and the secondary organic aerosol (SOA) in the troposphere via its oxidation products from the photochemical reactions. Tropospheric O3 and SOA can influenced radiation absorptions which can lead to the surface temperature increased. This study aims to determine hourly distribution of tropospheric isoprene over the Antarctic Peninsula during the Malaysian Antarctic Scientific Expedition Cruise 2016 (MASEC'16). In situ measurement of isoprene was taken over a 24-h period using a self-built, portable gas chromatography photoionization detector (PID), known as iDirac, on board the RV Australis. Biological parameters such as chlorophyll a (chl-a), particulate organic carbon (POC) and particulate inorganic carbon (PIC) detected by the Atmospheric Infrared Sounder (AIRS) aboard NASA's Aqua satellite during the cruise's period were compared to the measured isoprene. Hotspots of isoprene were measured, with isoprene being the highest over the region of King Sejong Research
Environmental science and pollution research international, Jan 8, 2017
The Antarctic continent is known to be an unpopulated region due to its extreme weather and clima... more The Antarctic continent is known to be an unpopulated region due to its extreme weather and climate conditions. However, the air quality over this continent can be affected by long-lived anthropogenic pollutants from the mainland. The Argentinian region of Ushuaia is often the main source area of accumulated hazardous gases over the Antarctic Peninsula. The main objective of this study is to report the first in situ observations yet known of surface ozone (O3) over Ushuaia, the Drake Passage, and Coastal Antarctic Peninsula (CAP) on board the RV Australis during the Malaysian Antarctic Scientific Expedition Cruise 2016 (MASEC'16). Hourly O3 data was measured continuously for 23 days using an EcoTech O3 analyzer. To understand more about the distribution of surface O3 over the Antarctic, we present the spatial and temporal of surface O3 of long-term data (2009-2015) obtained online from the World Meteorology Organization of World Data Centre for greenhouse gases (WMO WDCGG). Furt...
... 68 7 Local Non-Destructive Status Determination for Concentric Wire Shield Cables and Cables ... more ... 68 7 Local Non-Destructive Status Determination for Concentric Wire Shield Cables and Cables Sheathed in Lead James M. Feldman Nicholas Reinhardt Thomas Walsh ... Joshua Horwitz, Kate Morris, George Vrablik and John Rudy Accelerated Systems, Inc., Beverly, MA 01915 ...
Journal of Geophysical Research: Atmospheres, 2017
Rapid urbanization of cities has greatly modified the thermal and dynamic profile in the urban bo... more Rapid urbanization of cities has greatly modified the thermal and dynamic profile in the urban boundary layer. This paper attempts to study the interaction of urban heating and the local topographic‐induced flow circulation for a tropical coastal city, Greater Kuala Lumpur, in Malaysia. The role of sea‐and‐valley‐breeze‐orientated synoptic flow (SBOS) on the interaction is determined by comparing two intermonsoon periods. A state‐of‐the‐art numerical model, Advanced Research Weather Research and Forecasting model, is used to identify the influence of urbanization through modification of urban surfaces. The model reasonably reproduces the vertical sounding data and near‐surface weather parameters. The diurnal urban heating pattern is attributed to three predominant factors: (i) weak under calm and clear‐sky condition (morning heating), (ii) weak under larger atmospheric moisture content (late afternoon convection), and (iii) largest (1.4°C) due to differential cooling rate of urban a...
The modification of land use is known to be a major climate change driver to the local warming an... more The modification of land use is known to be a major climate change driver to the local warming and air quality in cities. Despite the reduction of NO x over the years, the Selangor state has captured a higher level of O 3 in year 2011. The measurement result has shown that the surge in O 3 level was attributed to the reduction of NO x /NMHC ratio. This paper hence attempted to identify the role of land use change from 1999 to 2011 on the ground ozone air quality in the tropical urban conurbation, Greater Kuala Lumpur (GKL), Selangor, Malaysia. With the state-of-the-art chemical weather prediction tool, WRF-Chem, the external synoptic factors and emission inventory were controlled when comparing the chronological land use changes. The results showed that the urban-induced temperature and wind bias in the tropical region has induced stronger wind to disperse the NO x and carries the TVOC from the suburban to the downwind urban region. The reduction of NO x /TVOC has gradually shifted towards the optimum O 3 formation regime in 2011. The formation of highly concentrated ozone becomes more sensitive to the increment of TVOC as the NO x level reduces in the urban. This highlights the essential involvement of TVOC in the ozone formation in lieu of the NO x reduction in the tropical city, a region with growing emitter of reactive biogenic ozone precursors.
One significant effect of urbanization is the modification of natural surfaces, local environment... more One significant effect of urbanization is the modification of natural surfaces, local environment, and thermal comfort. Farmland and agricultural land in Klang Valley conurbation, Malaysia have been replaced with engineered surfaces and infrastructures to accommodate the rapid population growth witnessed in the past decades. To understand the current environmental conditions of the conurbation, numerical Weather Research and Forecasting (WRF) model coupled to the Urban Canopy Model (UCM) was used. A model evaluation conducted against a network of observations showed an overall good performance of the model in predicting near-surface meteorological parameters. Also, an examination of spatiotemporal variability of urban parameters revealed a diurnal dependence of human physiological thermal conditions on urbanization level. A maximum urban heat island intensity (UHII) of~2.64 C was observed. In an effort to investigate the effect of urbanization level on the extremities of urban climatic conditions, two different experiments with varying urban/vegetation fractions were further simulated. The latter results indicate that urbanization level has a significant effect on the extremities of urban climatological parameters and spatial extent of the induced impacts. Furthermore, the effect of urbanization level on the mean urban outdoor thermal discomfort (UOTD) level was significant (with an increase of 0.7 C, 0.64 C and 0.04 observed) for temperature humidity index (THI), effective temperature index (ETI) and relative strain index (RSI), respectively. However, a non-significant (at 95% level) effect of urbanization level on the extremities of UOTD indices was observed.
observed on the spatiotemporal variation in meteorology of the area; especially along the coastli... more observed on the spatiotemporal variation in meteorology of the area; especially along the coastline bordering Strait of Malacca (by sea-land breezes) and the Titiwangsa mountain range (by mountain-valley breezes).
The garden city concept was adopted in the development of a new tropical city, Putrajaya, aimed a... more The garden city concept was adopted in the development of a new tropical city, Putrajaya, aimed at mitigating the effect of urban thermal modification associated with urbanisation, such as urban heat island (UHI). WRF/Noah/UCM coupled system was used to estimate the urban environment over the area and the individual thermal contributions of natural land use classes (vegetation and waterbody). A control experiment including all land use types describing the urban conditions of Putrajaya city agreed well with the observations in the region. A series of experiments was then conducted, in which vegetation and waterbody were successively replaced with an urban land use type, providing the basis for an assessment of their respective effect on urban thermal mitigation. Surface energy components, 2-m air temperature (T2m) and mixing ratio (Q2m), relative humidity (RH) and UHI intensity (UHII) showed variations for each land use class. Overall, an increase in urban surfaces caused a corresponding increase in the thermal conditions of the city. Conversely, waterbody and vegetation induced a daily reduction of 0.14 and 0.39 °C of T2m, respectively. RH, UHI and T2m also showed variations with urban fractions. A thermal reduction effect of vegetation is visible during mornings and nights, while that of water is minimally shown during daytime. However, during nights and mornings, canopy layer thermal conditions above waterbody remain relatively high, with a rather undesirable effect on the surrounding microclimate, because of its high heat capacity and thermal inertia.
This study aims to identify the vertical transport mechanisms that uplifted the forest fire emiss... more This study aims to identify the vertical transport mechanisms that uplifted the forest fire emissions from Sumatra to the upper troposphere during the June 2013 haze crisis. WRF-Chem is used to simulate the formation and transport of biomass-burning haze during the study period of 18 th to 26 th June 2013. The South-Southeast Asian synoptic weather patterns and their effects on the transport of biomass-burning emissions from Sumatra to Peninsular Malaysia were studied computationally to explain the phenomenon. Results show that PM 10 emissions were lifted to 200 hPa height (approximately 12 km) over the Strait of Malacca on 24 th June. The two identified vertical transport mechanisms confirmed a previously conjectured convergence over the Strait of Malacca and orographic lifting over Peninsular Malaysia. These mechanisms were able to uplift the biomass-burning emissions to the upper troposphere and this could have significant long-range transport and global climatic effects.
The urban boundary layer (UBL) is the internal advection layer of atmosphere above urban region w... more The urban boundary layer (UBL) is the internal advection layer of atmosphere above urban region which determines the exchanges of momentum, water and other atmospheric constituents between the urban land surface and the free troposphere. This paper tested the performance of three planetary boundary layer (PBL) physics schemes of Weather Research and Forecast (WRF) software to ensure the appropriate representation of vertical structure of UBL in Greater Kuala Lumpur (GKL). Comparison was conducted on the performance of respective PBL schemes to generate vertical and near-surface weather profile and rainfall. Mellor-Yamada- Janjíc (MYJ) local PBL scheme coupled with Eta MM5 surface layer scheme was found to predict the near-surface temperature and wind profile and mixing height better than the nonlocal schemes during the intermonsoonal period with least influences of the synoptic background weather.
The Weather Research and Forecasting (WRF) mesoscale model is used to study the effect of urban h... more The Weather Research and Forecasting (WRF) mesoscale model is used to study the effect of urban heating on the local climate of the largest urban agglomeration of Malaysia, Greater Kuala Lumpur (GKL) during a period of weak synoptic forcing. Urbanization has induced a modelled daily mean urban heat island (UHI) intensity of 0.9°C with a more severe heating (1.9°C) at night. The diurnal wind field of GKL is greatly affected by the circulation of land/sea breeze. The immense heat generated in the city accelerates the moisture-bearing sea breeze during the day and the induced vertical lifting simultaneously creates a conducive environment for convective precipitation on the upwind region. The urban heating effect and surface roughness weakens the evening flow circulations in the region and potentially inhibits dispersion of heat and atmospheric pollutants. Simulation of UHI phenomenon is especially sensitive to the characterization of urban grids through sensitivity evaluation of numerous land use maps and urban canopy model (UCM) settings. When compared to observations, the WRF model best captures the urban heating phenomenon with updated land use map and calibrated single layer UCM, while the simple bulk UCM setting performs better than the default complex single layer UCM.
The administrative capital of Malaysia, Putrajaya, is one of those cities built on the garden-cit... more The administrative capital of Malaysia, Putrajaya, is one of those cities built on the garden-city concept, however, few studies have been devoted to confirm the validity of the concept. Numerical mesoscale Weather Research and Forecasting (WRF) Model was coupled with Noah land surface model and a single layer urban canopy model (UCM) to investigate the existence and distribution of UHI, and the behaviour of urban canopy layer (2-m) temperature of Putrajaya city. Suitability of the model WRF employed in studying UHI phenomenon in the tropical city of Putrajaya, Malaysia was determined. Precincts in Putrajaya city were classified into local climate zones (LCZs) and the contribution of urban fabrics on the spatial and temporal variations of UHI was also investigated. Results of the model were verified with in situ studies of the area, and observational data from Alam Sekitar Malaysia Sdn Bhd (ASMA). Comparison with ASMA observational and in situ data reveals a satisfactory performance of the model. UHI intensity of Putrajaya exhibits a diurnal profile; increasing during the night to a peak value and then diminishing in the morning with a negligible value during midday. During the night hours, the UHII ranges from 1.9 • C to 3.1 • C in some of the precincts (LCZs) considered. Overall, average daily intensity of 0.79 • C heating was noted in Putrajaya for the study duration. The overall effect of urbanized LCZs heating of Putrajaya was normalized by the total amount of area reserved for vegetation.
This study presents first comprehensive thermochemical analysis of Bambara groundnut shell. Pyrol... more This study presents first comprehensive thermochemical analysis of Bambara groundnut shell. Pyrolysis characteristics was examined under non-isothermal degradation in nitrogen atmosphere at different heating rates (10, 15 and 20 C/min) using single-step global model kinetic model. The single-step global model average apparent activation energy was found to be 142.64 ± 5.7 kJ/mol. Pyrolysis was conducted in a fixed bed reactor. Effects of pyrolysis temperature (450e750 C), heating rate (20e50 C/min) and nitrogen flow rate (5e25 L/min) were investigated collectively. The process variables were optimized using response surface methodology with central composite design. Optimum bio-oil yield of 36.49 wt% was recorded at 600 C, 50 C/min and 11 L/min. The bio-oil, bio-char and non-condensable gas collected were comprehensively characterised. Energy analysis of the products was also evaluated. This study revealed that Bambara groundnut shell, a residue from food crop, is a potential source of energy precursors for development of a sustainable bioenergy system and biomaterials.
Urbanisation is associated with physical modifications of land surfaces and climate of a given ar... more Urbanisation is associated with physical modifications of land surfaces and climate of a given area. Studies of urbanisation effect on urban climate for Klang Valley region is below par. This research aims to bridge the gap by using a coupled Weather Research and Forecasting (WRF) model with the NOAH Land Surface Model (NOAH) and Urban Canopy Model (UCM)-WRF/NOAH/UCM to investigate the urban climatology of Klang Valley and the urbanisation of Putrajaya over a decade. In addition, evaluation of the garden city concept adopted in the development of Putrajaya city is also conducted. The model is first validated against a network of meteorological observations in the region to determine its suitability for urban climate investigations. Climatological variables (near-surface temperature, relative humidity, and wind speed) along with land use and land cover (LULC) changes; planetary boundary layer height (PBLH), and urban heat/cool islands (UHI/UCI) of the area are also investigated. The model evaluation shows good performance over the region. LULC changes demonstrates strong influence in thermal climatology variations. A mean maximum UHI intensity of ~4.2 ºC was observed in the urban canopy-layer of the Klang Valley. Results reveal that urbanisation of Putrajaya leads to 2-m temperature increase at the rate of ~1.66 ºC per decade, with the area experiencing a mean UHI intensity of ~2.1 ºC per day. Other climatological variables vary accordingly with the urbanisation processes. Evaluation of the garden city concept indicates that the adopted concept causes a reduction in 2-m air temperature of the Putrajaya area, amounting to ~0.53 ºC per day; with vegetation contributing more (~0.39 ºC) to the daily reduction relative to water bodies (~0.14 ºC). Location of the city in the tropics accustomed with high intensity of daily solar radiation masked the cooling potentials of the concept to some extent.
International Journal of Simulation and Process Modelling, 2017
The application of gears, especially spur gear, is widely available in most engineering applicati... more The application of gears, especially spur gear, is widely available in most engineering applications. Especially for high module steel spur gear, it is used extensively in heavy machineries such as cranes and metal crushers. Therefore, it is crucial to avoid catastrophic damage to gears by understanding the crack behaviour. Provided the crack does not propagate into the rim, only minor accidents are likely to happen or else catastrophe may be expected again. Therefore, the study of crack behaviour on stress intensity factor (SIF) with different magnitude of moment was conducted. This study implemented the application of extended finite element method (XFEM) in ABAQUS to overcome the limitations of a conventional method, the finite element method (FEM). The need of re-meshing was avoided in this simulation. The crack propagation pathways were visualised using the 'STATUSXFEM'.
British Journal of Environment and Climate Change, Jan 10, 2015
Despite increased interest on the urban heat island (UHI) phenomenon, there are limited UHI studi... more Despite increased interest on the urban heat island (UHI) phenomenon, there are limited UHI studies on cities built using the green-city concept of Sir Ebenezer Howard [1]. The administrative capital of Malaysia, Putrajaya is one of such cities built using the green-city concept. The objective of this study was to confirm the effectiveness of the green city concept using the National Centre for Atmospheric Research (NCAR) numerical technique. Numerical mesoscale Weather Research and Forecasting (WRF) Model was coupled with Noah land surface model and a single layer urban canopy model (UCM) to investigate the existence and distribution of UHI, and the behavior of urban canopy layer (2-m) temperature of Putrajaya city. Few studies have been conducted using the NCAR numerical technique (WRF) to explore Malaysian climatology. Suitability of the model employed in studying UHI phenomenon of Putrajaya city was determined using in-situ study of the area, and observational data from AlamSekitar Malaysia SdnBhd (ASMA). Contribution of urban fabrics on the spatial and temporal variations of UHI was also investigated. Comparison with ASMA and in-situ data revealed a satisfactory performance of the model.UHI intensity (UHII) of Putrajaya exhibits a diurnal profile; increasing during the night to a peak value and then diminishing towards morning with a negligible value in the midday. In the night time, the UHII ranges from Original Research Article
One of the worst haze events to ever hit Peninsular Malaysia occurred in June 2013 due to smoke f... more One of the worst haze events to ever hit Peninsular Malaysia occurred in June 2013 due to smoke from Riau, Central Sumatra. While biomass-burning in the region is common, the early occurrence of a haze episode of this magnitude was uncharacteristic of the seasonality of extreme fire events, which usually occur between August and October in the Maritime Continent (MC). This study aims to investigate the phenomenology of the June 2013 haze event and its underlying meteorological forcing agents. The aerosol and meteorological environment during the event is examined using the Moderate Resolution Imaging Spectroradiometer (MODIS) active fire hotspot detections and aerosol optical thickness retrievals, satellite-based precipitation retrievals, and meteorological indices. These datasets are then supported by a WRF-Chem simulation to provide a comprehensive picture of the event's meteorology and aerosol transport phenomenology. While extreme fire events are more characteristic of El Nino years, the MODIS fire count over the MC in June for the years 2001-2015 was highest in 2013 when neutral El Nino/Southern Oscillation (ENSO) conditions prevailed. Although, the mean daily precipitation for June 2013 was below average for June 2003-2015. An early active tropical cyclone (TC) season occurred in 2013, and results show that the combined induced subsidence and flow enhancement due to TC Bebinca and the dry phases of a strong Madden-Julian Oscillation (MJO) event contributed to the event intensification. Results also show that Bebinca induced a decrease in surface relative humidity of at least 10% over Riau, where fire hotspots were concentrated.
Isoprene (C5H8) plays an important role in the formation of surface ozone (O3) and the secondary ... more Isoprene (C5H8) plays an important role in the formation of surface ozone (O3) and the secondary organic aerosol (SOA) in the troposphere via its oxidation products from the photochemical reactions. Tropospheric O3 and SOA can influenced radiation absorptions which can lead to the surface temperature increased. This study aims to determine hourly distribution of tropospheric isoprene over the Antarctic Peninsula during the Malaysian Antarctic Scientific Expedition Cruise 2016 (MASEC'16). In situ measurement of isoprene was taken over a 24-h period using a self-built, portable gas chromatography photoionization detector (PID), known as iDirac, on board the RV Australis. Biological parameters such as chlorophyll a (chl-a), particulate organic carbon (POC) and particulate inorganic carbon (PIC) detected by the Atmospheric Infrared Sounder (AIRS) aboard NASA's Aqua satellite during the cruise's period were compared to the measured isoprene. Hotspots of isoprene were measured, with isoprene being the highest over the region of King Sejong Research
Environmental science and pollution research international, Jan 8, 2017
The Antarctic continent is known to be an unpopulated region due to its extreme weather and clima... more The Antarctic continent is known to be an unpopulated region due to its extreme weather and climate conditions. However, the air quality over this continent can be affected by long-lived anthropogenic pollutants from the mainland. The Argentinian region of Ushuaia is often the main source area of accumulated hazardous gases over the Antarctic Peninsula. The main objective of this study is to report the first in situ observations yet known of surface ozone (O3) over Ushuaia, the Drake Passage, and Coastal Antarctic Peninsula (CAP) on board the RV Australis during the Malaysian Antarctic Scientific Expedition Cruise 2016 (MASEC'16). Hourly O3 data was measured continuously for 23 days using an EcoTech O3 analyzer. To understand more about the distribution of surface O3 over the Antarctic, we present the spatial and temporal of surface O3 of long-term data (2009-2015) obtained online from the World Meteorology Organization of World Data Centre for greenhouse gases (WMO WDCGG). Furt...
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Papers by Kenobi Morris