Displaying publications 21 - 40 of 191 in total

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  1. Fulltext The correlation between serum leptin and blood pressure after exposure to noise at work
    Rahma MS, Mustafa BE, Razali A, Shamsuddin N, Althunibat OY
    Noise Health, 2013 Nov-Dec;15(67):375-8.
    PMID: 24231415 DOI: 10.4103/1463-1741.121223
    Several epidemiologic studies have reported that exposure to noise is associated with cardiovascular disease. The increased body weight is often associated with metabolic as well as increased blood pressure. The aim of this study is to investigate the correlation between the elevation of blood pressure and serum leptin hormones due to the effects of noise in the work place. A total of 80 volunteer males where included in this study with an age range between of 20 and 45 years, they were divided in two groups equally, the 1 st group were exposed to noise in the workplace while the 2 nd group were not. The individual noise exposure was determined by using a sound level meter. The range of noise was 80-100 dBA. Body Mass Index was also taken for each individual by a standard measure, blood pressure was measured by OMRON sphygmomanometer and serum leptin was measured through venous blood sample analysis enzyme linked immunosorbent assay. Spearman rank order correlation was used to examine the correlations between Blood pressure value (Systolic, Diastolic) and Leptin. All the relationships between parameters showed a positive correlation. Systolic and diastolic blood pressure values had a significant correlation to leptin hormone level in comparison to the control. There was a significant relation between leptin and blood pressure. leptin effects on the sympathetic nervous system may provide a partial explanation. Therefore, Leptin might have diverse cardiovascular actions.
    Matched MeSH terms: Noise, Occupational/adverse effects*
  2. Correlation between subjective and objective assessment of magnetic resonance (MR) images
    Chow LS, Rajagopal H, Paramesran R, Alzheimer's Disease Neuroimaging Initiative
    Magn Reson Imaging, 2016 07;34(6):820-831.
    PMID: 26969762 DOI: 10.1016/j.mri.2016.03.006
    Medical Image Quality Assessment (IQA) plays an important role in assisting and evaluating the development of any new hardware, imaging sequences, pre-processing or post-processing algorithms. We have performed a quantitative analysis of the correlation between subjective and objective Full Reference - IQA (FR-IQA) on Magnetic Resonance (MR) images of the human brain, spine, knee and abdomen. We have created a MR image database that consists of 25 original reference images and 750 distorted images. The reference images were distorted with six types of distortions: Rician Noise, Gaussian White Noise, Gaussian Blur, DCT compression, JPEG compression and JPEG2000 compression, at various levels of distortion. Twenty eight subjects were chosen to evaluate the images resulting in a total of 21,700 human evaluations. The raw scores were then converted to Difference Mean Opinion Score (DMOS). Thirteen objective FR-IQA metrics were used to determine the validity of the subjective DMOS. The results indicate a high correlation between the subjective and objective assessment of the MR images. The Noise Quality Measurement (NQM) has the highest correlation with DMOS, where the mean Pearson Linear Correlation Coefficient (PLCC) and Spearman Rank Order Correlation Coefficient (SROCC) are 0.936 and 0.938 respectively. The Universal Quality Index (UQI) has the lowest correlation with DMOS, where the mean PLCC and SROCC are 0.807 and 0.815 respectively. Student's T-test was used to find the difference in performance of FR-IQA across different types of distortion. The superior IQAs tested statistically are UQI for Rician noise images, Visual Information Fidelity (VIF) for Gaussian blur images, NQM for both DCT and JPEG compressed images, Peak Signal-to-Noise Ratio (PSNR) for JPEG2000 compressed images.
    Matched MeSH terms: Signal-To-Noise Ratio
  3. Measurement of subtle auditory deficit in tinnitus patients with normal audiometric thresholds using evoked otoacoustic emissions and threshold equalizing noise tests
    Ishak WS, Zhao F, Rajenderkumar D, Arif M
    Int Tinnitus J, 2013;18(1):35-44.
    PMID: 24995898 DOI: 10.5935/0946-5448.20130006
    The general consensus on the roles of hearing loss in triggering tinnitus seems not applicable in patients with normal hearing thresholds. The absence of hearing loss on the audiogram in this group of patients poses a serious challenge to the cochlear theories in explaining tinnitus generation in this group of patients.
    Matched MeSH terms: Noise*
  4. Fulltext Binding Affinity of a Highly Sensitive Au/Ag/Au/Chitosan-Graphene Oxide Sensor Based on Direct Detection of Pb2+and Hg2+Ions
    Kamaruddin NH, Bakar AAA, Mobarak NN, Zan MSD, Arsad N
    Sensors (Basel), 2017 Oct 06;17(10).
    PMID: 28984826 DOI: 10.3390/s17102277
    The study of binding affinity is essential in surface plasmon resonance (SPR) sensing because it allows researchers to quantify the affinity between the analyte and immobilised ligands of an SPR sensor. In this study, we demonstrate the derivation of the binding affinity constant, K, for Pb2+and Hg2+ions according to their SPR response using a gold/silver/gold/chitosan-graphene oxide (Au/Ag/Au/CS-GO) sensor for the concentration range of 0.1-5 ppm. The higher affinity of Pb2+to binding with the CS-GO sensor explains the outstanding sensitivity of 2.05 °ppm-1against 1.66 °ppm-1of Hg2+. The maximum signal-to-noise ratio (SNR) upon detection of Pb2+is 1.53, and exceeds the suggested logical criterion of an SNR. The Au/Ag/Au/CS-GO SPR sensor also exhibits excellent repeatability in Pb2+due to the strong bond between its functional groups and this cation. The adsorption data of Pb2+and Hg2+on the CS-GO sensor fits well with the Langmuir isotherm model where the affinity constant, K, of Pb2+and Hg2+ions is computed. The affinity of Pb2+ions to the Au/Ag/Au/CS-GO sensor is significantly higher than that of Hg2+based on the value of K, 7 × 10⁵ M-1and 4 × 10⁵ M-1, respectively. The higher shift in SPR angles due to Pb2+and Hg2+compared to Cr3+, Cu2+and Zn2+ions also reveals the greater affinity of the CS-GO SPR sensor to them, thus supporting the rationale for obtaining K for these two heavy metals. This study provides a better understanding on the sensing performance of such sensors in detecting heavy metal ions.
    Matched MeSH terms: Signal-To-Noise Ratio
  5. Fulltext Prenatal auditory stimulation induces physiological stress responses in developing embryos and newly hatched chicks
    Hanafi SA, Zulkifli I, Ramiah SK, Chung ELT, Kamil R, Awad EA
    Poult Sci, 2023 Feb;102(2):102390.
    PMID: 36608455 DOI: 10.1016/j.psj.2022.102390
    Prenatal stress may evoke considerable physiological consequences on the developing poultry embryos and neonates. The present study aimed to determine prenatal auditory stimulation effects on serum levels of ceruloplasmin (CPN), alpha-1-acid glycoprotein (AGP), corticosterone (CORT), and heat shock protein 70 (Hsp70) regulations in developing chicken embryos and newly hatched chicks. Hatching eggs were subjected to the following auditory treatments; 1) control (no additional sound treatment other than the background sound of the incubator's compressors at 40 dB), 2) noise exposure (eggs were exposed to pre-recorded traffic noise at 90 dB) (NOISE), and 3) music exposure (eggs were exposed to Mozart's Sonata for Two Pianos in D Major, K 488 at 90 dB) (MUSIC). The NOISE and MUSIC treatments were for 20 min/h for 24 h (a total of 8 h/d), starting from embryonic days (ED) 12 to hatching. The MUSIC (1.37 ± 0.1 ng/mL) and NOISE (1.49 ± 0.2 ng/mL) treatments significantly elevated CPN at ED 15 compared to the Control (0.82 ± 0.04 ng/mL) group and post-hatch day 1 (Control, 1.86 ± 0.2 ng/mL; MUSIC, 2.84 ± 0.4 ng/mL; NOISE, 3.04 ± 0.3 ng/mL), AGP at ED 15 (Control, 39.1 ± 7.1 mg/mL; MUSIC, 85.5 ± 12.9 mg/mL; NOISE, 85.4 ± 15.1 mg/mL) and post-hatch day 1 (Control, 20.4 ± 2.2 mg/mL; MUSIC, 30.5 ± 4.7 mg/mL; NOISE, 30.3 ± 1.4 mg/mL). CORT significantly increased at ED 15 in both MUSIC (9.024 ± 1.4 ng/mL) and NOISE (12.15 ± 1.6 ng/mL) compared to the Control (4.39 ± 0.7 ng/mL) group. On the other hand, MUSIC exposed embryos had significantly higher Hsp70 expression than their Control and NOISE counterparts at ED 18 (Control, 12.9 ± 1.2 ng/mL; MUSIC, 129.6 ± 26.4 ng/mL; NOISE, 13.3 ± 2.3 ng/mL) and post-hatch day 1 (Control, 15.2 ± 1.7 ng/mL; MUSIC, 195.5 ± 68.5 ng/mL; NOISE, 13.2 ± 2.7 ng/mL). In conclusion, developing chicken embryos respond to auditory stimulation by altering CPN, AGP, CORT, and Hsp70. The alterations of these analytes could be important in developing embryos and newly hatched chicks to cope with stress attributed to auditory stimulation.
    Matched MeSH terms: Noise/adverse effects
  6. Hearing impairment and contributing factors among fertilizer factory workers
    Saffree Jeffree M, Ismail N, Awang Lukman K
    J Occup Health, 2016 Sep 30;58(5):434-443.
    PMID: 27488035
    INTRODUCTION: Hearing impairment remains the main occupational health problem in the manufacturing industry, and its contributing factors have not been well controlled.

    METHODS: Unmatched case control and comparative studies were carried out among fertilizer factory workers in Sarawak with the aim of determining contributing factors for hearing impairment. Respondents consisted of 49 cases that were diagnosed from 2005 to 2008 with 98 controls from the same work places. Chi-square test and Mann-Whitney test were used in a univariate analysis to determine the association between hearing impairment and the contributing risks being studied.

    RESULTS: The results of the univariate analysis showed that hearing impairment was significantly (p<0.05) associated with older age, lower education level, high smoking dose, high occupational daily noise dose, longer duration of service, infrequent used of hearing protection device (HPD), and low perception of sound on HPD usage. Multivariate logistic regression of hearing impairment after controlling for age found the following five variables: occupational daily noise dose ≥50% (OR 3.48, 95% CI 1.36-8.89), ≥15 years of services (OR 2.92, 95% CI 1.16-7.33), infrequent use of HPD (OR 2.79, 95% CI 1.15-6.77), low perception of sound on HPD (POR 2.77, 95% CI 1.09-6.97), and smoking more than 20 packs per year (OR 4.71, 95% CI 1.13-19.68).

    DISCUSSION: In conclusion, high occupational noise exposure level, longer duration of service, low perception of sound on HPD, infrequent used of HPD, and smoking more than 20 packs per year were the contributing factors to hearing impairment, and appropriate intervention measures should be proposed and taken into considerations.

    Matched MeSH terms: Hearing Loss, Noise-Induced/etiology*; Hearing Loss, Noise-Induced/prevention & control; Noise, Occupational/adverse effects*
  7. Fulltext Auditory Brainstem Response (ABR) Findings With Click and CE-Chirp Stimulations in Noise-Exposed Participants
    Zakaria MN, Abdul Wahab NA, Awang MA
    Noise Health, 2017 12 2;19(87):112-113.
    PMID: 29192621 DOI: 10.4103/nah.NAH_2_17
    Matched MeSH terms: Noise, Occupational*
  8. Effects of background noise on recording of portable transient-evoked otoacoustic emission in newborn hearing screening
    Salina H, Abdullah A, Mukari SZ, Azmi MT
    Eur Arch Otorhinolaryngol, 2010 Apr;267(4):495-9.
    PMID: 19727788 DOI: 10.1007/s00405-009-1080-y
    Transient-evoked otoacoustic emission (TEOAE) is a well-established screening tool for universal newborn hearing screening. The aims of this study are to measure the effects of background noise on recording of TEOAE and the duration required to complete the test at various noise levels. This study is a prospective study from June 2006 until May 2007. The study population were newborns from postnatal wards who were delivered at term pregnancy. Newborns who were more than 8-h old and passed a hearing screening testing using screening auditory brainstem response (SABRe) were further tested with TEOAE in four different test environments [isolation room in the ward during non-peak hour (E1), isolation room in the ward during peak hour (E2), maternal bedside in the ward during non-peak hour (E3) and maternal bedside in the ward during peak hour (E4)]. This study showed that test environment significantly influenced the time required to complete testing in both ears with F [534.23] = 0.945; P < 0.001 on the right ear and F [636.54] = 0.954; P < 0.001 on the left. Our study revealed that TEOAE testing was efficient in defining the presence of normal hearing in our postnatal wards at maternal bedside during non-peak hour with a specificity of 96.8%. Our study concludes that background noise levels for acceptable and accurate TEOAE recording in newborns should not exceed 65 dB A. In addition, when using TEOAE assessment in noisy environments, the time taken to obtain accurate results will greatly increase.
    Matched MeSH terms: Noise*
  9. Fulltext Experimental Analysis of Heat-Affected Zone (HAZ) in Laser Cutting of Sugar Palm Fiber Reinforced Unsaturated Polyester Composites
    Masoud F, Sapuan SM, Ariffin MKAM, Nukman Y, Bayraktar E
    Polymers (Basel), 2021 Feb 26;13(5).
    PMID: 33652612 DOI: 10.3390/polym13050706
    In this paper, the influence of processing input parameters on the heat-affected zone (HAZ) of three different material thicknesses of sugar palm fiber reinforced unsaturated polyester (SPF-UPE) composites cut with a CO2 laser was investigated. Laser power, traverse speed, and gas pressure were selected as the most influential input parameters on the HAZ to optimize the HAZ response with fixing all of the other input parameters. Taguchi's method was used to determine the levels of parameters that give the best response to the HAZ. The significance of input parameters was also determined by calculating the max-min variance of the average of the signal-to-noise ratio (S/N) ratio for each parameter. Analysis of variation (ANOVA) was used to determine each input parameter's contribution to the influence on HAZ depth. The general results show that the minimum levels of laser power and the highest levels of traverse speed and gas pressure gave the optimum response to the HAZ. Gas pressure had the most significant effect on the HAZ, with contribution decreases as the material thickness increased, followed by the traverse speed with contribution increases with the increase in material thickness. Laser power came third, with a minimal contribution to the effect on the HAZ, and it did not show a clear relationship with the change in material thickness. By applying the optimum parameters, the desired HAZ depth could be obtained at relatively low values.
    Matched MeSH terms: Signal-To-Noise Ratio
  10. Fulltext Cortical signal-in-noise coding varies by noise type, signal-to-noise ratio, age, and hearing status
    Maamor N, Billings CJ
    Neurosci Lett, 2017 01 01;636:258-264.
    PMID: 27838448 DOI: 10.1016/j.neulet.2016.11.020
    The purpose of this study was to determine the effects of noise type, signal-to-noise ratio (SNR), age, and hearing status on cortical auditory evoked potentials (CAEPs) to speech sounds. This helps to explain the hearing-in-noise difficulties often seen in the aging and hearing impaired population. Continuous, modulated, and babble noise types were presented at varying SNRs to 30 individuals divided into three groups according to age and hearing status. Significant main effects of noise type, SNR, and group were found. Interaction effects revealed that the SNR effect varies as a function of noise type and is most systematic for continuous noise. Effects of age and hearing loss were limited to CAEP latency and were differentially modulated by energetic and informational-like masking. It is clear that the spectrotemporal characteristics of signals and noises play an important role in determining the morphology of neural responses. Participant factors such as age and hearing status, also play an important role in determining the brain's response to complex auditory stimuli and contribute to the ability to listen in noise.
    Matched MeSH terms: Signal-To-Noise Ratio*
  11. Fulltext Serum leptin and corticosterone levels after exposure to noise stress in rats
    Chandralekha G, Jeganathan R, Viswanathan, Charan JC
    Malays J Med Sci, 2005 Jan;12(1):51-6.
    PMID: 22605947
    Even though extensive studies have been conducted on the effect of noise exposure on hearing apparatus / auditory system, information on the effect of noise on the other body functions is sparse. The present study examined the effect of exposure of albino rats to acute and chronic noise stress on two important interlaced endocrine levels. In acute experiments the animals were exposed to 120 dB noise for a duration of 1, 2, 3 hrs. In chronic experiments the animals were exposed to noise for one hour daily for 30, 60 and 90 days. Plasma corticosterone and leptin levels were measured in these animals. There was significant elevation in the levels of corticosterone and leptin after exposure to noise stress. The elevation in corticosterone level after noise stress is in agreement with earlier reports. So noise acts like a stressor and elevates the secretion of the corticosterone, the stress hormone and leptin, the product of the ob gene there is an elevation in leptin levels after noise stress.
    Matched MeSH terms: Noise
  12. Fulltext Noise exposure effect on testicular histology, morphology and on male steroidogenic hormone
    Swami CG, Ramanathan J, Charan Jeganath C
    Malays J Med Sci, 2007 Jul;14(2):28-35.
    PMID: 23515367 MyJurnal
    The noise stress, after it passes through the hearing apparatus, not only affects the auditory apparatus but also other body functions. The alterations in the levels of cortical hormone, adrenocorticosterone, nor-epinephrine hormone (which are primarily considered as stress hormones) on follicular stimulating hormone, testosterone, and lutinizing hormone were reported in relation with stress. Male albino rats weighing 200 to 250 grams were exposed to 100 dB of noise for one hour and three hours in acute group and daily one hour exposure for 60 day, and 90 day in chronic group. The serum testosterone levels were measured in these animals. There was significant reduction in serum testosterone levels and this was similar with earlier reports. The tissues were collected for light and confocal microscopic study. 100dB of traffic noise exposure of varying duration had definite permanent effect on testicular histology and morphology and on the male sex hormone. The adaptation mechanism was noticed at the hormonal level only but the structural changes noticed were definite and permanent. The agglutinated dead sperms revealed the possibility of infertily when chronically exposed to noise stress.
    Matched MeSH terms: Noise
  13. Fulltext Identification of Noise Levels for Skill Training Activities, Equipment, Machines and Power Tools at TVET Institutes in Malaysia
    Abdul Rahim KA, Jewaratnam J, Che Hassan CR
    Int J Environ Res Public Health, 2022 Nov 27;19(23).
    PMID: 36497858 DOI: 10.3390/ijerph192315783
    The use of various machines, equipment and power tools at TVET Institute causes the institute's environment to be exposed to noise hazards that are similar to the industry. However, not much data has been published regarding noise exposure at TVET institutes. This study was carried out to document the noise exposure of work activities training in public TVET institutes in Malaysia that implement skill training programs in metal fabrication, furniture manufacturing and automotive maintenance. The identification of excessive noise, task-based noise exposure monitoring and source measurement was conducted. The noise contribution from each work activity to the daily A-weighted noise exposure level and sound pressure level emitted by machines and equipment was documented. The findings of this study recorded 20 activities with task-based noise contribution to the daily A-weighted noise exposure level between 75.3 dB and 95 dB. Based on the findings, the training environment at the TVET institutes has a risk of operating with excessive noise. The documented data can be used in planning the implementation of suitable noise control measures in TVET institutes.
    Matched MeSH terms: Noise; Noise, Occupational*
  14. Fulltext CT brain image advancement for ICH diagnosis
    Shaik Amir NS, Kang LZ, Mukari SA, Sahathevan R, Chellappan K
    Healthc Technol Lett, 2020 Feb;7(1):1-6.
    PMID: 32190334 DOI: 10.1049/htl.2018.5003
    A critical step in detection of primary intracerebral haemorrhage (ICH) is an accurate assessment of computed tomography (CT) brain images. The correct diagnosis relies on imaging modality and quality of acquired images. The authors present an enhancement algorithm which can improve the clarity of edges on CT images. About 40 samples of CT brain images with final diagnosis of primary ICH were obtained from the UKM Medical Centre in Digital Imaging and Communication in Medicine format. The images resized from 512 × 512 to 256 × 256 pixel resolution to reduce processing time. This Letter comprises of two main sections; the first is denoising using Wiener filter, non-local means and wavelet; the second section focuses on image enhancement using a modified unsharp masking (UM) algorithm to improve the visualisation of ICH. The combined approach of Wiener filter and modified UM algorithm outperforms other combinations with average values of mean square error, peak signal-to-noise ratio, variance and structural similarity index of 2.89, 31.72, 0.12 and 0.98, respectively. The reliability of proposed algorithm was evaluated by three blinded assessors which achieved a median score of 65%. This approach provides reliable validation for the proposed algorithm which has potential in improving image analysis.
    Matched MeSH terms: Signal-To-Noise Ratio
  15. Widely tunable multi-wavelength Brillouinerbium fiber laser utilizing low SBS threshold photonic crystal fiber
    Mohd Nasir MN, Yusoff Z, Al-Mansoori MH, Abdul Rashid HA, Choudhury PK
    Opt Express, 2009 Jul 20;17(15):12829-34.
    PMID: 19654689
    A widely tunable low stimulated Brillouin scattering (SBS) photonic crystal fiber (PCF) based multi-wavelength Brillouin-erbium fiber laser is presented. The fiber laser structure utilizes a pre-amplified Brillouin pump (BP) technique with 100 m of PCF and a tunable band-pass filter within a Fabry-Perot cavity. A total of 14 Brillouin Stokes lines can be tuned over 29 nm from 1540 nm to 1569 nm. The wide tunability was only limited by the bandwidth of the tunable band-pass filter. A constant channel spacing of 0.079 nm and signal to noise ratio (SNR) of more than 20 dB for each Brillouin Stokes lines were also observed.
    Matched MeSH terms: Signal-To-Noise Ratio
  16. Autoregressive Wiener filtering in a scanning electron microscopy imaging system
    Sim KS, Kamel NS, Chuah HT
    Scanning, 2005 6 7;27(3):147-53.
    PMID: 15934507
    In this paper, we propose to use the autoregressive (AR)-based interpolator with Wiener filter and apply the idea to scanning electron microscope (SEM) images. The concept for combining the AR-based interpolator with Wiener filtering comes from the essential requirement of Wiener filtering for accurate and consistent estimation of the power of the noise in images prior to filter implementation. The resultant filter is called AR-Wiener filter. The proposed filter is embedded onto the frame grabber card of the scanning electron microscope (SEM) for real-time image processing. Different images are captured using SEM and used to compare the performances of the conventional Wiener and the proposed AR-Wiener technique.
    Matched MeSH terms: Noise
  17. Fulltext A Study on Distortion Estimation Based on Image Gradients
    Chin SC, Chow CO, Kanesan J, Chuah JH
    Sensors (Basel), 2022 Jan 14;22(2).
    PMID: 35062601 DOI: 10.3390/s22020639
    Image noise is a variation of uneven pixel values that occurs randomly. A good estimation of image noise parameters is crucial in image noise modeling, image denoising, and image quality assessment. To the best of our knowledge, there is no single estimator that can predict all noise parameters for multiple noise types. The first contribution of our research was to design a noise data feature extractor that can effectively extract noise information from the image pair. The second contribution of our work leveraged other noise parameter estimation algorithms that can only predict one type of noise. Our proposed method, DE-G, can estimate additive noise, multiplicative noise, and impulsive noise from single-source images accurately. We also show the capability of the proposed method in estimating multiple corruptions.
    Matched MeSH terms: Signal-To-Noise Ratio
  18. Fulltext Monitoring noise level during Sukhoi aircraft operation at no. 11 Squadron
    Mohd Rizal Hamid, Ahmad Faruq Mohamad Rosli, Manokaran, Kesavan, Siti Shafiqa Shamira Hashin, Nik Mohd Dzarrin Ghifari Azmy, Baba Md Deros, et al.
    ZULFAQAR International Journal of Defence Science, Engineering & Technology, 2020;3(2):25-31.
    MyJurnal
    Awareness of occupational noise and its effects is growing. At No. 11 squadron base, Sukhoi jet was identified as the main culprit of occupational noise that affects not just the employees of the base but also civilian people in the surrounding area. The objective of the study is to identify the noise level produced by Sukhoi two-engines jet during maintenance operations. Investigations were carried out using Bruel & Kjaer 2250 sound level meter hand-analyser. Measurements were performed directly under the Sukhoi jet body and then 10 metres, 50 metres, 100 metres, 1000 metres and 1500 metres away. The jet engines could operate at two levels, at 72% RPM and at 85% RPM. The civilians are only exposed to its noise from more than 1000 metres away. The results from this study are analysed and noise mapping and noise contouring are produced which give the level of noise exposure. The maximum noise is recorded t 122dB(A) and the minimum is at 60dB(A). The farther the noise from the jet is measured, the lower the values recorded. From the noise mapping, the effects of noise exposures on both the employees at the base and the civilian at the neighbouring surrounding could be identified. Even though the exposures are only for 5-10 minutes, it is still considered as a threat
    Matched MeSH terms: Noise, Occupational
  19. Fulltext A stochastic simulation framework for the prediction of strategic noise mapping and occupational noise exposure using the random walk approach
    Han LM, Haron Z, Yahya K, Bakar SA, Dimon MN
    PLoS One, 2015;10(4):e0120667.
    PMID: 25875019 DOI: 10.1371/journal.pone.0120667
    Strategic noise mapping provides important information for noise impact assessment and noise abatement. However, producing reliable strategic noise mapping in a dynamic, complex working environment is difficult. This study proposes the implementation of the random walk approach as a new stochastic technique to simulate noise mapping and to predict the noise exposure level in a workplace. A stochastic simulation framework and software, namely RW-eNMS, were developed to facilitate the random walk approach in noise mapping prediction. This framework considers the randomness and complexity of machinery operation and noise emission levels. Also, it assesses the impact of noise on the workers and the surrounding environment. For data validation, three case studies were conducted to check the accuracy of the prediction data and to determine the efficiency and effectiveness of this approach. The results showed high accuracy of prediction results together with a majority of absolute differences of less than 2 dBA; also, the predicted noise doses were mostly in the range of measurement. Therefore, the random walk approach was effective in dealing with environmental noises. It could predict strategic noise mapping to facilitate noise monitoring and noise control in the workplaces.
    Matched MeSH terms: Noise, Occupational*
  20. Fulltext A new SIR-based sigmoid power control game in cognitive radio networks
    Al-Gumaei YA, Noordin KA, Reza AW, Dimyati K
    PLoS One, 2014;9(10):e109077.
    PMID: 25286044 DOI: 10.1371/journal.pone.0109077
    Interference resulting from Cognitive Radios (CRs) is the most important aspect of cognitive radio networks that leads to degradation in Quality of Service (QoS) in both primary and CR systems. Power control is one of the efficient techniques that can be used to reduce interference and satisfy the Signal-to-Interference Ratio (SIR) constraint among CRs. This paper proposes a new distributed power control algorithm based on game theory approach in cognitive radio networks. The proposal focuses on the channel status of cognitive radio users to improve system performance. A new cost function for SIR-based power control via a sigmoid weighting factor is introduced. The existence of Nash Equilibrium and convergence of the algorithm are also proved. The advantage of the proposed algorithm is the possibility to utilize and implement it in a distributed manner. Simulation results show considerable savings on Nash Equilibrium power compared to relevant algorithms while reduction in achieved SIR is insignificant.
    Matched MeSH terms: Signal-To-Noise Ratio*
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