Herni Halim

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Papers by Herni Halim

Effect of Ficus pumila, Ficus pumila ‘Variegata’ and Vernonia elliptica on Sound Absorption Performance of Green Wall Fences

Urban Forestry and Arboriculture in Malaysia, 2022

Ultrasonic (US)-Assisted Electrocoagulation (EC) Process for Oil and Grease (O&G) Removal from Restaurant Wastewater

Separations

Restaurant wastewater contains a high concentration of O&G, up to 3434 mg/L. This study aims to (... more Restaurant wastewater contains a high concentration of O&G, up to 3434 mg/L. This study aims to (a) assess the efficiency of EC combined with US methods for O&G removal in restaurant wastewater, (b) identify the optimum condition for COD degradation using EC treatment via response surface methodology (RSM), and (c) determine the morphological surface of the aluminium (Al) electrode before and after EC treatment. The wastewater samples were collected from the Lembaran cafeteria at the Universiti Sains Malaysia (USM). The efficiency of EC, US, and US-EC, combined methods for O&G removal, was investigated using a batch reactor (pH 7). The interelectrode distance (ID, 2–6 cm), electrolysis time (T, 15–35 min), and current density (CD, 40–80 A/m2) were analysed, followed by RSM. The response variables were O&G (1000 mg/L) and chemical oxygen demand (COD low range, 1000 mg/L). The central composite design (CCD) with a quadratic model was used to appraise the effects and interactions of th...

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Palm Oil Clinker as Noise Control Materials

Elaeis guineensis, 2022

Palm oil clinker (POC) is a waste from the production process of palm oil, a hard and porous mate... more Palm oil clinker (POC) is a waste from the production process of palm oil, a hard and porous materials. Many studies have focused on the effect of POC use on strength while this study discusses the ability of POC in concrete to absorb sound and its relationship with concrete properties. The study was done by replacing natural river sand in stages of 25, 50, 75 and 100 percent in a mixture of 1: 4 (cement: sand). Sound absorption coefficient (SAC), strength and physical properties affect the SAC were measured. Although POC significantly reduced the compressive strength but all specimens poses good strength more than 5 N/mm2. An interesting result is that POC reduces interconnected porosity and total porosity when replacement is 100% but increases interconnected and total porosity when replacement is between 50 and 75%. SAC at 315 Hz was found has good relationship with percentage of POC and density. It is obtained that POC 50% yield good strength and sufficient SAC that can address t...

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Experimental Investigation on Behaviour of Cross-Flow Thermal Effluent Discharge in Free Surface Flow

Malaysian Journal of Civil Engineering, 2009

Thermal discharges such as from power stations or industries into rivers causing degradation of w... more Thermal discharges such as from power stations or industries into rivers causing degradation of water quality. A study was conducted in the laboratory to investigate the changes of the ambient temperature caused by thermal effluent discharged into the flow. A cross-flow thermal effluent is discharged from the bed of the channel. Thermal effluent flow rates of 0.133 liter/s and 0.05 liter/s and ambient flow rates of 20 liter/s and 10 liter/s were used in the study. Observation of thermal mixing process in the channel is concentrated in the near-field zone. The thermal dispersion patterns were observed along the channel through the isothermal lines; while the changes of ambient temperature are studied from the experimental data. The results indicate that the temperature changes are drastic in the near-field mixing zone. Then it gradually reduces along the channel until reaches the far-field mixing zone. Lower layer of the flow experiences high excess temperature compared to middle and upper layers of the flow. Meanwhile, larger effluent flow rate produces higher excess temperature in the receiving water body than small effluent flow rate. Based on experimental data, equations of excess temperature and dispersion were established.

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Influence of Particle Size and Zeta Potential in Treating Highly Coloured Old Landfill Leachate by Tin Tetrachloride and Rubber Seed

International Journal of Environmental Research and Public Health, 2022

Old leachate normally has a low organic compound content, poor biodegradability and is hard to bi... more Old leachate normally has a low organic compound content, poor biodegradability and is hard to biologically treat. The efficacy of tetravalent metal salts as a coagulant and the application of a natural coagulant as a flocculant in landfill leachate treatment is still inconclusive. Hence, this study aimed to evaluate the potential application of tin tetrachloride (SnCl4) as the main coagulant and the rubber seed (Hevea brasiliensis) (RS) as the natural coagulant aid as the sole treatment in eradicating highly coloured and turbid stabilised landfill leachate present at one of the old local landfills in Malaysia. The standard jar test conducted revealed that SnCl4 was able to eliminate 99% and 97.3% of suspended solids (SS) and colour, respectively, at pH8, with 10,000 mg/L dosages, an average particle size of 2419 d·nm, and a zeta potential (ZP) of −0.4 mV. However, RS was found to be ineffective as the main coagulant and could only remove 46.7% of SS and 76.5% of colour at pH3 with ...

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Microscopic validation through sensitivity analysis for the pedestrian’s directional switching behavior model

For the past four decades, the development of different kinds of model can be seen to simulate co... more For the past four decades, the development of different kinds of model can be seen to simulate complex crowd behavior. Modeling and simulation have become the best choice of methodology to understand and predict certain phenomena in a crowd by its replication. The crucial traits in human crowd behavior and the emergence of several empirically observed collective behavior in a crowd could be reproduced and explained [1, 2, 3, and 4]. In this contribution, the switching action behavior of pedestrian is highlighted and the one-way sensitivity analysis is performed to validate the developed switching action behavior model. Since, in the current state, no available empirical data to be compared with the model’s outcomes, the choice of sensitivity analysis is significant.

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Effectiveness of noise barriers at residential areas in Klang Valley, Malaysia

The use of environmental noise barrier has increased as concerns of side effects of noise polluti... more The use of environmental noise barrier has increased as concerns of side effects of noise pollution in the environment grow. However, a lot of complaints from the residents occur after the installation of the noise barrier regarding its effectiveness. Thus, this study is carried out to determine the effectiveness of existing noise barriers such as vegetation, concrete hollow block, and panel concrete. This study is designed to evaluate the influence of source of noise (traffic composition) as well as meteorological condition towards level of noise at study sites with and without the presence of noise barrier. The results of the study reveals that LAeq in all study sites throughout all measurement periods recorded 61.9 dB(A) to 74.8 dB(A) during daytime (morning, afternoon, and evening) and 57.6 dB(A) to 73.2 dB(A) during night time. These results exceed the noise limit in Malaysia guidelines (daytime = 60 dB(A) and night time = 50 dB(A)). Results of PCA show the percentages of the t...

The Potential of Napier Grass Leaf Fibres as an Acoustic Absorber

Acoustic absorbers are introduced to treat poor acoustic enviroment in rooms. However, many avail... more Acoustic absorbers are introduced to treat poor acoustic enviroment in rooms. However, many available acoustic absorbers in the market are composed of hazardous materials. Therefore, there are demands for the use of sustainable materials in the production of acoustic absorbers. This research investigated the sound absorption potential of grass leaf fibres, i.e. Napier grass, as material for acoustic absorbers. Various bound Napier grass fibre samples, with and without binder under normal press with different thickness, were prepared and tested by using an impedance tube test for sound absorption coefficient (SAC) determination. Samples with binder under hot press with thickness of 10mm were also prepared. The results revealed that 5mm and 20mm fibres, respectively, when bonded with urea formaldhyde (UF) under normal press and with thickness of 30mm, produced a relatively high SAC for frequencies at 500 Hz, 1000 Hz and 2500 Hz, and thus resulted in a high average NRC value of 0.59. T...

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Distribution of bus stops at train stations: Acomparison between Kyoto subway line andKelana Jaya line

In this era of high mobility, private vehicles are still dominating the traffic despite various a... more In this era of high mobility, private vehicles are still dominating the traffic despite various alternatives such as bus and train had been implemented to increase the public transport ridership. For instance, in Penang, a free shuttle service between Weld Quay and Komtar (launched in 2009) and Bridge Express Shuttle Transit (BEST) Park and Ride (launched in 2011) had faced difficulties to get high ridership. Thus, a headway study by Haron et al. [1] had improved the bus schedule on most of the bus routes.

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Reduction of COD and Highly Coloured Mature Landfill Leachate by Tin Tetrachloride with Rubber Seed and Polyacrylamide

Water, 2021

Tin tetrachloride (SnCl4) as a coagulant and rubber seed (Hevea brasiliensis) (RS), and polyacryl... more Tin tetrachloride (SnCl4) as a coagulant and rubber seed (Hevea brasiliensis) (RS), and polyacrylamide (PAM) as the coagulant aid were investigated in this work to treat matured and stabilised landfill leachate rich in COD and colour. A standard jar test was conducted at different pH values and dosages of coagulant/coagulant aid. When SnCl4 acted as the primary coagulant, the optimum conditions occurred at pH 8 and 10,000 mg/L dosages, with 97.3% and 81% reductions of colour and COD, respectively. Both RS and PAM were not effective when used alone. When RS was used as the coagulant aid, the dosage of SnCl4 was reduced to 8000 mg/L. The colour reduction was maintained at 97.6%, but the COD removal dropped to 43.1%. In comparison, when PAM was supplemented into 6000 mg/L SnCl4, the reduction in colour was maintained at 97.6%, and the COD removal was almost at par when SnCl4 was used alone. The addition of polymers as the coagulant aid helped in improving the sludge properties with a b...

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Removal of colour and suspended solids from landfill leachate using Tin tetrachloride (SnCl4): The effects of pH, zeta potential, and particle sizes

International Journal of Environmental Analytical Chemistry, 2021

Old landfill leachate is normally rich in colloidal particles, has low organic compound, poor bio... more

Road Traffic Noise Levels at Different Types of Residential Areas in Nibong Tebal, Penang

International Journal of Integrated Engineering, 2019

Traffic vehicles on the road networks during their movement create noise that has greater impact ... more Traffic vehicles on the road networks during their movement create noise that has greater impact on environment. The sources, the receivers and the place of transition, where the sound wave propagates, are the three vital parameters for the field of noise acoustics. For this research, the aim of this study is to assess traffic noise levels between different types of residential areas in Nibong Tebal, Penang. The study is carried out in order to achieve the following three main objectives, which are to assess the level of traffic noise at selected residential areas, to characterize the traffic flow composition nearby study areas, and to compare noise levels between low density and terraced house residential areas. The noise levels measurements were carried out periodically in the morning (from 0700 to 1100), evening (from 1600 to 1900), and at night (from 2200 to 2300) for 15 minutes using a sound level meter. The traffic characteristics were measured simultaneously during noise levels measurements. The highest equivalent continuous noise levels for the low density residential areas was at Kampung Batu 2 in the evening with 65.9 dB(A), while for the medium density residential areas, Taman Sri Acheh contributed 68.60 dB(A) during the morning. The lowest equivalent continuous noise levels were obtained at Kampung Simpang Tiga in the morning that contributed 54.9 dB(A) for low density residential areas. However, the minimum equivalent continuous noise levels obtained for the medium density residential areas was at Taman Ilmu Indah in the morning with 63.10 dB(A). The results obtained, clearly show that the equivalent continuous noise level for all study sites exceeded the maximum permissible sound level for medium density areas during daytime (from 7.00 am to 10.00 pm), which is 55 dB(A), while at night time (from 10.00 pm to 7.00 am) is 45 dB(A), and for low density residential areas during daytime (from 7.00 am to 10.00 pm) is 55 dB(A), while at night time (from 10.00 pm to 7.00 am) is 45 dB(A), respectively. These values are based on the guidelines for environmental noise limits and control by the Department of Environment, Malaysia.

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Comparison of Road Traffic Noise at Residential Areas in Klang Valley, Selangor and Nibong Tebal, Penang

International Journal of Integrated Engineering, 2019

Noise is an undesirable or disturbance sound that can cause irritation to a listener and damage t... more

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Noise barrier as an option to reduce road traffic noise from highways in Klang valley, Malaysia

A noise barrier can be defined as an obstacle to sound propagation between the sound source and t... more A noise barrier can be defined as an obstacle to sound propagation between the sound source and the listener, where the noise propagates either above or around the barrier. In Malaysia, there is a lack of literature regarding noise barriers, including design of noise barriers that have been erected. This study investigates the design of existing noise barriers; vegetation, masonry concrete hollow block and panel concrete at three urban residential areas in Klang Valley region. The finding in this study indicates that noise barriers of masonry concrete hollow block and concrete panel height are 4.6 m and 2.8 m, respectively. These height of noise barriers exceeded line of sight at sampling point with 1.5 m of microphone height from the ground. This may imply diffraction of sound wave on top of the noise barriers. Apart from that, both concrete hollow block and panel concrete noise barriers were perforated in each panel and block to absorb some energy of sound and consequently helps to reduce noise from highways.A noise barrier can be defined as an obstacle to sound propagation between the sound source and the listener, where the noise propagates either above or around the barrier. In Malaysia, there is a lack of literature regarding noise barriers, including design of noise barriers that have been erected. This study investigates the design of existing noise barriers; vegetation, masonry concrete hollow block and panel concrete at three urban residential areas in Klang Valley region. The finding in this study indicates that noise barriers of masonry concrete hollow block and concrete panel height are 4.6 m and 2.8 m, respectively. These height of noise barriers exceeded line of sight at sampling point with 1.5 m of microphone height from the ground. This may imply diffraction of sound wave on top of the noise barriers. Apart from that, both concrete hollow block and panel concrete noise barriers were perforated in each panel and block to absorb some energy of sound and consequently helps to reduce noise from hig...

Simulation of Pedestrian Walking Through Angled-Corridors for Evacuation Behaviour Study

IOP Conference Series: Materials Science and Engineering, 2020

The effect of acute- and obtuse-angled-corridors on the evacuation behaviour is rarely studied. I... more The effect of acute- and obtuse-angled-corridors on the evacuation behaviour is rarely studied. In the previous work, we have confirmed that corridor with less than 90° turning angle has negative impact to the pedestrians walking behaviour due to the tendency of the pedestrians to slow down their motion when approaching the turning of the corridor. This restrict the flow of walkers during high-density situation and cause congestion near that turning of the corridor. In this contribution, empirical data collected from previous experimental work is utilised to further study the effect of turning angle on the evacuation behaviour. The simulations of walking through angled-corridor were reproduced which reflects evacuation scenarios. Three different types of angled-corridor are taken into consideration (a 60°-, a 90°-, and a 135°-angled-corridors) with different sets of number of pedestrians (NOP: 60, 70, 80, 90 and 100). Three metrics of evacuation behaviour measurement are reported: (...

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The effect of vehicle weight on the sound produced by transverse rumble strips

Journal of Mechanical Engineering and Sciences, 2019

Transverse rumble strips (TRS) are commonly used as traffic calming measure in the vicinity of pr... more Transverse rumble strips (TRS) are commonly used as traffic calming measure in the vicinity of premises. So far research have been extensively concentrated on the effect of vehicle type and speed on the noise produced by TRS, and very little research focused on the effect of vehicle weight. Do these vehicles produce extremely higher sound level parallel to their heavier weight? This is important as in reality, traffic flow consist of light, medium and heavy vehicles, which are also important sources of noise. This study investigated the effect of vehicle weight, such as gross vehicle weight (GVW) when transited on TRS, particularly with emphasis on impulsivity content. The objectives of this research were to: (1) determine the effect of GVW on noise generation when a vehicle transits on TRS and (2) assess the effect of GVW on the impulsivity of noise. Data from vehicles with weight between 800 kg - 8000 kg were collected based on previous research where these vehicles were tested o...

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A Theoretical Framework for Understanding Pedestrian Behaviour Attributes Based on Spatial Interaction

IOP Conference Series: Materials Science and Engineering, 2018

Current trend shows there is an exponential increase in rail traffic passenger volume in Malaysia... more Current trend shows there is an exponential increase in rail traffic passenger volume in Malaysia, causing authorities to be aware in improving the pedestrians' facilities and safety. Kuala Lumpur Sentral Station (KLSS) is the largest transportation hub in Malaysia and, as of May 2017, the user reaches up to 180,000 users daily. In this contribution, a theoretical framework is presented to understand the pedestrians' behaviour attributes at rail transit terminal based on pedestrians' spatial interactions. The Distinct Element Method (DEM) will be employed to model the dynamics of pedestrian's crowd behaviour. The validated crowd dynamics model will be demonstrated in evacuation capacity estimation in KLSS. Evacuating people quickly and safely can greatly reduce casualty and economic losses. As for this contribution, more concern is on the spatial interaction of pedestrian at the RTT and the proposed framework. This framework paper will describe the flow in details on conducting the study of spatial intersection.

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Experimental study and computational analysis on pedestrians behaviour walking through angled-corridor

AIP Conference Proceedings, 2018

Empirical investigation of trajectories and desired walking velocity of pedestrian walking through angled-corridor

AIP Conference Proceedings, 2017

Trajectories and walking velocity are two crucial metrics that become a basis in pedestrian flow ... more Trajectories and walking velocity are two crucial metrics that become a basis in pedestrian flow analysis. Both metrics are governed by many factors, and some of the factors considered in this study are the angle of a corridor, track distance, number density of pedestrians, uni- or bi-directional flow and width of corridor. This paper is aimed at reporting empirical investigation of the effect of angled-corridor on pedestrian flow by postulating microscopically the trajectories and desired walking velocity of pedestrians. We have conducted one controlled experiment consists of 30 numbers of unidirectional walking tasks on a built corridor for different degrees of corner (60°, 90°, and 135°) by maintaining the width of the corridor as 2.25 m. A total of 990 samples of pedestrians walking behaviour were collected during the experiments. The finding summarised the pedestrians’ desired walking velocity and the trajectories of walking pedestrians for each type of the angled-corridor. The averaged-desired walking velocity of female and male (female; male) pedestrians for 60°-, 90°-, and 135°-corridor are (1.37 m/s; 1.42 m/s), (1.08 m/s; 1.03 m/s), and (1.10 m/s; 1.08m/s), respectively. The normal L-shaped corridor (90° corridor) gives the lowest averaged-desired walking velocity compared to 60° and 135°. Besides, the trajectory of pedestrians shows the preference of pedestrians to use the inner track of the corridor due to the shorter distance. About 15.21% of pedestrians changed their trajectory from outer to inner track during the experiment for all angled-corridors. With regards to that scenario, the flow was affected and the pedestrians started to queue was witnessed during the experiment. These finding could be notable interest for all evacuation studies that aim a good strategies and design solution in order to prevent crowd disaster.Trajectories and walking velocity are two crucial metrics that become a basis in pedestrian flow analysis. Both metrics are governed by many factors, and some of the factors considered in this study are the angle of a corridor, track distance, number density of pedestrians, uni- or bi-directional flow and width of corridor. This paper is aimed at reporting empirical investigation of the effect of angled-corridor on pedestrian flow by postulating microscopically the trajectories and desired walking velocity of pedestrians. We have conducted one controlled experiment consists of 30 numbers of unidirectional walking tasks on a built corridor for different degrees of corner (60°, 90°, and 135°) by maintaining the width of the corridor as 2.25 m. A total of 990 samples of pedestrians walking behaviour were collected during the experiments. The finding summarised the pedestrians’ desired walking velocity and the trajectories of walking pedestrians for each type of the angled-corridor. The averaged-desired walki...

Trajectories and walking velocity of pedestrian walking through angled-corridors: A unidirectional scenario

IOP Conference Series: Materials Science and Engineering, 2019

When comparing corner and straight corridor to acute- and obtuse- angled-corridors, effects of la... more When comparing corner and straight corridor to acute- and obtuse- angled-corridors, effects of later types of corridors on the pedestrian dynamics is rarely studied. Rationally, there will be changes to the pedestrian walking behavior when approaching and walking through angled-corridor due to the turning angle. This could trigger restrictions to the flow of walkers and causing congestion near that turning angle. Hence, this study is purposely to investigate empirically the characteristics of pedestrians when walking through different angled-corridors (60°, 90° and 135°). Controlled experiment of pedestrians walking through built angled- corridors was conducted at the Multipurpose Hall of USM, involving 60 local undergraduate students. Thirty walking tasks were performed by considering different number of pedestrians (NOP: 1, 15, 30, 45 and 60). Video-based tracking of pedestrian’s trajectories walking through angled-corridors was performed and effects on walking characteristics and...

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