Displaying publications 1 - 20 of 191 in total

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  1. Fulltext Digital Filtering Techniques for Performance Improvement of Golay Coded TDM-FBG Sensor
    Elgaud MM, Zan MSD, Abushagur AAG, Hamzah AE, Mokhtar MHH, Arsad N, et al.
    Sensors (Basel), 2021 Jun 23;21(13).
    PMID: 34201845 DOI: 10.3390/s21134299
    For almost a half-decade, the unique autocorrelation properties of Golay complementary pairs (GCP) have added a significant value to the key performance of conventional time-domain multiplexed fiber Bragg grating sensors (TDM-FBGs). However, the employment of the unipolar form of Golay coded TDM-FBG has suffered from several performance flaws, such as limited improvement of the signal-to-noise ratio (SNIR), noisy backgrounds, and distorted signals. Therefore, we propose and experimentally implement several digital filtering techniques to mitigate such limitations. Moving averages (MA), Savitzky-Golay (SG), and moving median (MM) filters were deployed to process the signals from two low reflectance FBG sensors located after around 16 km of fiber. The first part of the experiment discussed the sole deployment of Golay codes from 4 bits to 256 bits in the TDM-FBG sensor. As a result, the total SNIR of around 8.8 dB was experimentally confirmed for the longest 256-bit code. Furthermore, the individual deployment of MA, MM, and SG filters within the mentioned decoded sequences secured a further significant increase in SNIR of around 4, 3.5, and 3 dB, respectively. Thus, the deployment of the filtering technique alone resulted in at least four times faster measurement time (equivalent to 3 dB SNIR). Overall, the experimental analysis confirmed that MM outperformed the other two techniques in better signal shape, fastest signal transition time, comparable SNIR, and capability to maintain high spatial resolution.
    Matched MeSH terms: Signal-To-Noise Ratio*
  2. Fulltext Bilateral Heschl’s Gyrus display non-reciprocity in connectivity during the performance of simple arithmetic addition task
    Yusoff, A.N., Te, L.H., Mukari, S.Z.M., Abd Hamid, A.I.
    Jurnal Sains Kesihatan Malaysia, 2016;14(1):37-45.
    MyJurnal
    Heschl’s gyrus (HG) is known to interact with other auditory related areas of the same hemisphere during the performance
    of an auditory cognitive task. However, the information about how it interacts with the opposite HG is still lacking.
    The aim of this study was to investigate the psychophysiologic interaction (PPI) between the bilateral HG during a
    simple arithmetic addition task and to verify the role of noise as an experimental factor that would modulate the PPI.
    Functional magnetic resonance imaging (fMRI) scans were performed on eighteen healthy participants, in which a
    single-digit addition task were solved during in-quiet (AIQ) and in-noise (AIN) conditions. The fMRI data were analysed
    using Statistical Parametric Mapping (SPM8). The interaction between the bilateral HG was investigated using PPI
    analysis. The response in right HG was found to be linearly influenced by the activity in left HG, vice-versa, for both
    in-quiet and in-noise conditions. The connectivity from right to left HG in noisy condition seemed to be modulated
    by noise, while the modulation is relatively small oppositely, indicating a non-reciprocal behavior. A two-way PPI
    model between right and left HG is suggested. The connectivity from right to left HG during a simple addition task in
    noise is driven by a higher ability of right HG to perceive the stimuli in a noisy condition. Both the bilateral HGs took
    part in the cognitive processes of arithmetic addition from which the interactions between the two were found to be
    different in noise.
    Matched MeSH terms: Noise
  3. Fulltext The effects of background noise on brain activation during a verbal working memory task
    Mohamad, M., Yusoff, A.N., Mukari, S.Z.M., Abdullah, A., Abd Hamid, A.I.
    Malaysian Journal of Medicine and Health Sciences, 2014;10(1):29-38.
    MyJurnal
    This study was carried out to investigate the effects of noisy background on brain activation during a working memory task. Fourteen healthy male subjects underwent silent functional Magnetic Resonance Imaging (fMRI) scans while listening to words presented verbally against quiet (WIS) and noisy (WIN) backgrounds. The stimuli were binaurally presented to the subjects at 70 dB sound pressure level (SPL) in both conditions. Group results indicated significant (p < 0.001) bilateral widespread of brain activations in the primary auditory cortex, superior temporal gyrus, inferior frontal gyrus, supramarginal gyrus and inferior parietal lobes during WIS. Additional significant activation was observed in the middle cingulate cortex and anterior cingulate cortex during WIN, suggesting the involvement of cingulate cortex in working memory processing against a noisy background. The mean percentage of signal change in all regions was higher during WIN as compared to WIS. Right hemispheric predominance was observed for both conditions in primary auditory cortex and middle frontal gyrus and this could be attributed to the increased difficulty of the tasks. The results obtained from this study demonstrated that background noise increased task demand and difficulty. Task demand was found to play an important role in determining the activation magnitude in the brain areas during working memory task.
    Matched MeSH terms: Noise
  4. Fulltext The Acquisition, Analyses and Interpretation of fMRI Data: A Study on Functional Specialisation in Primary Auditory Cortices
    Yusuf, A.N., Abdul Hamid, K., Mohamad, M., Abd hamid, A.I.
    Medicine & Health, 2008;3(2):300-317.
    MyJurnal
    In this study, functional magnetic resonance imaging (fMRI) is used to investigate func-tional specialisation in human auditory cortices during listening. A silent fMRI paradigm was used to reduce the scanner sound artefacts on functional images. The subject was instructed to pay attention to the white noise stimulus binaurally given at an inten-sity level of 70 dB higher than the hearing level for normal people. Functional speciali-sation was studied using the Matlab-based Statistical Parametric Mapping (SPM5) software by means of fixed effects (FFX), random effects (RFX) and conjunction analyses. Individual analyses on all subjects indicated asymmetrical bilateral activation of the left and right hemispheres in Brodmann areas (BA) 22, 41 and 42, involving the primary and secondary auditory cortices. The percentage of signal change is larger in the BA22, 41 and 42 on the right as compared to the ones on the left (p>0.05). The average number of activated voxels in all the respective Brodmann areas are higher in the right hemisphere than in the left (p>0.05). FFX results showed that the point of maximum intensity was in the right BA41 whereby 599±1 activated voxels were ob-served in the right temporal lobe as compared to 485±1 in the left temporal lobe. The RFX results were consistent with that of FFX. The analysis of conjunction which fol-lowed, showed that the right BA41 and left BA22 as the common activated areas in all subjects. The results confirmed the specialisation of the right auditory cortices in pro-cessing non verbal stimuli.
    Matched MeSH terms: Noise
  5. Fulltext Er3+/Yb3+ co-doped fibre amplifier demonstrates significant gain enhancement with improved noise figure
    Muhd-Yassin, S.Z., Harun, S.W., Ahmad, H., Abd-Rahman, M.K.
    ASM Science Journal, 2008;2(2):163-168.
    MyJurnal
    An efficient erbium/ytterbium co-doped fibre amplifier was demonstrated by using a dual-stage partial doublepass structure with a band-pass filter (BPF). The amplifier achieved the maximum small signal gain of 56 dB and the corresponding noise figure of 4.66 dB at 1536 nm with an input signal power and total pump power of –50 dBm and 140 mW, respectively. Compared with a conventional single-stage amplifier, the maximum gain enhancement of 16.99 dB was obtained at 1544 nm with the corresponding noise figure was improved by 2 dB. The proposed amplifier structure only used a single pump source with a partial double pass scheme to provide a high gain and dual-stage structure to provide the low noise figure.
    Matched MeSH terms: Noise
  6. The effect of non-native and non-regional speech testing on a multi-lingual population
    Quar TK, Soli SD, Chan YF, Ishak WS, Abdul Wahat NH
    Int J Audiol, 2017 02;56(2):92-98.
    PMID: 27686009 DOI: 10.1080/14992027.2016.1210828
    OBJECTIVE: This study was conducted to evaluate the speech perception of Malaysian Chinese adults using the Taiwanese Mandarin HINT (MHINT-T) and the Malay HINT (MyHINT).

    DESIGN: The MHINT-T and the MyHINT were presented in quiet and noise (front, right and left) conditions under headphones. Results for the two tests were compared with each other and with the norms for each test.

    STUDY SAMPLE: Malaysian Chinese native speakers of Mandarin (N = 58), 18-31 years of age with normal hearing.

    RESULTS: On average, subjects demonstrated poorer speech perception ability than the normative samples for these tests. Repeated measures ANOVA showed that speech reception thresholds (SRTs) were slightly poorer on the MHINT-T than on the MyHINT for all test conditions. However, normalized SRTs were poorer by 0.6 standard deviations for MyHINT as compared with MHINT-T.

    CONCLUSIONS: MyHINT and MHINT-T can be used as norm-referenced speech perception measures for Mandarin-speaking Chinese in Malaysia.

    Matched MeSH terms: Noise/adverse effects*
  7. Fulltext SNR improvements in self-heterodyne detection technique for laser linewidth measurements
    Manimaran, R., Abdul-Rashid, H.A.
    ASM Science Journal, 2008;2(2):133-137.
    MyJurnal
    This paper proposes a signal-to-noise-ratio (SNR) improvement by using an external phase modulator that allowed flexible control of the spectrum amplitude by varying the modulation index for linewidth measurements. Compared with the conventional self-heterodyne detection technique, the results obtained in this study showed an SNR improvement as high as 10 dB. This 10 dB improvement in SNR could help to reduce the usage of a particular length of a single mode fibre (normally about 50 Km) when measuring a linewidth in the region of 10 kHz.
    Matched MeSH terms: Noise; Signal-To-Noise Ratio
  8. Fulltext Noise-induced hearing loss among quarry workers in a north-eastern state of malaysia: a study on knowledge, attitude and practice
    Ismail AF, Daud A, Ismail Z, Abdullah B
    Oman Med J, 2013 Sep;28(5):331-6.
    PMID: 24044059 DOI: 10.5001/omj.2013.96
    Noise is known to be one of the environmental and occupational hazards listed in the Factory and Machinery Act 1967. Quarries with loud deafening sounds from trucks and machineries pose the risk of noise-induced hearing loss to workers. This study was designed to assess the knowledge, attitude and practice towards noise-induced hearing loss and to determine the prevalence of noise-induced hearing loss and its associated factors among quarry workers in a north-eastern state of Malaysia.
    Matched MeSH terms: Hearing Loss, Noise-Induced; Noise, Occupational
  9. Fulltext Multi-level basis selection of wavelet packet decomposition tree for heart sound classification
    Safara F, Doraisamy S, Azman A, Jantan A, Abdullah Ramaiah AR
    Comput Biol Med, 2013 Oct;43(10):1407-14.
    PMID: 24034732 DOI: 10.1016/j.compbiomed.2013.06.016
    Wavelet packet transform decomposes a signal into a set of orthonormal bases (nodes) and provides opportunities to select an appropriate set of these bases for feature extraction. In this paper, multi-level basis selection (MLBS) is proposed to preserve the most informative bases of a wavelet packet decomposition tree through removing less informative bases by applying three exclusion criteria: frequency range, noise frequency, and energy threshold. MLBS achieved an accuracy of 97.56% for classifying normal heart sound, aortic stenosis, mitral regurgitation, and aortic regurgitation. MLBS is a promising basis selection to be suggested for signals with a small range of frequencies.
    Matched MeSH terms: Signal-To-Noise Ratio
  10. Fulltext Prevalence of occupational diseases among small and medium industry workers in Malaysia: a systematic review
    Muhammad Zubir Yusof, Nik Ahmad Kamal Nik Mahmod, Nor Azlina A. Rahman, Ailin Razali, Niza Samsuddin, Nik Mohamed Nizan Nik Mohamed, et al.
    Journal of Clinical and Health Sciences, 2019;4(2):4-30.
    MyJurnal
    Occupational diseases are one of the major health problems related to workplace hazards.
    However, the epidemiological data for this problem is scarce especially among Small and
    Medium Industry (SMI) workers. These workers are vulnerable to occupational health problem
    due to lack of knowledge and implementation of health and safety in the workplace. In Malaysia,
    most of the SMI workers have limited coverage for basic occupational health services which
    may worsen their health. Thus, this article aims to provide a review on the burden of
    occupational health problems among them. The electronic and library searches were used to
    extract the information from both published and unpublished articles that were not limited to any
    year of publication until 2017. One hundred and ninety-six published articles and 198
    unpublished articles were retrieved from the database. Only 19 published articles and 25
    unpublished articles met the eligibility criteria. Prevalence data of occupational
    diseases/poisoning, including overall and body specific (musculoskeletal disorders) was
    extracted in raw data from the eligible studies. Prevalent statistics on occupational
    musculoskeletal diseases (1.3% - 97.6%), noise-induced hearing loss (29.4% - 73.3%),
    occupational skin diseases (10.5% - 84.3%), respiratory (1.9% - 92.2%) and occupational
    poisoning (14.9% - 17.7%) among the working population is different within published papers
    compared to unpublished ones. In Malaysia, there are no specific statistic that give a true picture
    of the burden of occupational diseases in the SMI. However, this review concludes that
    musculoskeletal diseases are significant occupational problems among SMI workers.
    Matched MeSH terms: Hearing Loss, Noise-Induced
  11. Correlation between 18F-FDG dosage and SNR on various BMI patient groups tested in NEMA IEC PET phantom
    Waeleh N, Saripan MI, Musarudin M, Mashohor S, Ahmad Saad FF
    Appl Radiat Isot, 2021 Oct;176:109885.
    PMID: 34385090 DOI: 10.1016/j.apradiso.2021.109885
    The present study was conducted to determine quantitatively the correlation between injected radiotracer and signal-to-noise ratio (SNR) based on differences in physiques and stages of cancer. Eight different activities were evaluated with modelled National Electrical Manufacturers Association (NEMA) of the International Electrotechnical Commission (IEC) PET's phantom with nine different tumour-to-background ratio (TBR). The findings suggest that the optimal value of dosage is required for all categories of patients in the early stages of cancer diagnosis.
    Matched MeSH terms: Signal-To-Noise Ratio
  12. Prevalence and associated factors of hearing impairment in aviation and manufacturing industry in Selangor
    Ahmad Syazrin Muhamad
    Journal of Occupational Safety and Health, 2011;8(2):35-44.
    MyJurnal
    Sound is one of the source of energy generated by vibration and is carried through the air in a form of pressure waves (Frederick, 1975). This pressure waves consist of pulsation or vibration of molecules of an elastic medium such as gas, liquid and even solid (Gerber, 1974). Due to its nature, sound can be irritating when it is excessive. The excessive amount of sound is called noise. Exposure to noise is common to the workers working at the industry. This can lead to hearing loss. Hearing loss is one of the most common health problems in the industrialized world. Working activities have been related to noise exposure due to increase use of machine that generates sounds. Many workers throughout the world experience hazardous noise exposure which is ≥ 85 decibels (dB) (Seter, 1998). Based on the previous study in the European region, most of the employers had difficulties to compensate workers diagnosed with hearing loss or hearing impairment cause by the working nature. (Rachiotis et al., 2006). According to European Survey on Working Conditions, about 7% of the workers considered that their work affects their health in the form of hearing disorders. Occupational risk factors for hearing loss include occupational noise, whole body vibration, work-related diseases and exposure to chemical. In this report, we specified in the noise exposure level of the workers.
    Matched MeSH terms: Noise, Occupational
  13. Fulltext SOA-based multi-wavelength source
    Harun, S.W., Sulaiman, A.H., Ahmad, H.
    ASM Science Journal, 2009;3(1):27-30.
    MyJurnal
    We demonstrate a multi-wavelength light source using a semiconductor optical amplifier (SOA) in conjunction with an array waveguide grating (AWG). The experimental results showed more than 20 channels with a wavelength separation of 0.8 nm and an optical signal-to-noise ratio of more than 10 dB under room temperature. The channels operated at the wavelength region from 1530.4 nm to 1548.6 nm, which corresponded to AWG filtering wavelengths with SOA drive current of 350 mA. The proposed light source had the advantages of a simple and compact structure, multi-wavelength operation and the system could be upgraded to generate more wavelengths.
    Matched MeSH terms: Signal-To-Noise Ratio
  14. Fulltext An erbium/ytterbium co-doped fibre amplifier using 1058 nm pumping
    Harun, S.W., Tamjis, M.R., Muhd-Yassin, S.Z., Abd-Rahman, M.K., Ahmad, H.
    ASM Science Journal, 2007;1(2):129-133.
    MyJurnal
    This paper demonstrates an erbium/ytterbium co-doped fi bre amplifi er (EYDFA) which used a pumping wavelength of 1058 nm, whereby the amplifi cation was assisted by the energy transfer between Yb and Er ions. The energy transfer increased the erbium doping concentration limit that was imposed by concentration quenching in erbium-doped fi bre. The optimum length was obtained at 4m~6m for erbium/ytterbium co-doped fi bre with Er ion concentration of 1000 p.p.m. This enabled the development of a compact amplifi er with a shorter gain medium compared to erbium-doped fi bre amplifi ers which use a gain medium of up to 15 m. A 1058 nm pumping wave-length was used for the EYDFA, as 1480 nm pumping resulted in severely degraded gain and noise fi gures because the energy transfer could not be achieved. The use of the optical isolator improved the small signal gain and noise fi gure by about 4.8 dB and 1.6 dB, respectively. Without the isolator, gain saturation and a noise fi gure penalty were observed due to the oscillating laser which was created at around 1534 nm by spurious refl ection. This showed that the usage of optical isolators was an important aspect to consider when designing an EYDFA.
    Matched MeSH terms: Noise
  15. Fulltext Investigating brain activation and neural efficacy during simple arithmetic addition task in quiet and in noise: an fMRI study
    Ng, Sok Bee, Ahmad Nazlim Yusoff, Teng, Xin Ling, Aini Ismafairus Abd. Hamid
    Jurnal Sains Kesihatan Malaysia, 2014;12(1):23-33.
    MyJurnal
    Knowledge about the hemodynamic model that mediates synaptic activity and measured magnetic resonance signal is essential in understanding brain activation. Neural efficacy is a hemodynamic parameter that would change the evoked hemodynamic responses. In this work, brain activation and neural efficacy of the activated brain areas during simple addition task in two different backgrounds were studied using fMRI. The objectives were to determine the activated areas during the performance of arithmetic addition in quiet (AIQ) and noisy (AIN) background and to investigate the relationship between neural efficacy and height extent of activation for the respective areas. Eighteen healthy male participants performed simple arithmetic addition in quiet and in noise. Bilateral cerebellum, superior temporal gyrus (STG), temporal pole (TP) and supplementary motor area (SMA) were significantly (p < 0.05) activated during AIQ and AIN. Left middle frontal gyrus (L-MFG), right superior frontal gyrus (R-SFG), right superior orbital gyrus (R-SOG) and bilateral insula were more active in quiet as compared to in noise while the left middle cingulate cortex (L-MCC), left amygdala (L-AMG), right temporal pole (R-TP) and left cerebellum (L-CER) were more active in noise as compared to in quiet. The t value for most of the activated regions was found to be inversely proportional to the neural efficacy. Significant (p < 0.05) negative relationship between t value and neural efficacy were found for R-STG and bilateral cerebellum during AIQ, while for AIN, similar relationships were found in R-CER, R-STG and R-TP. This study suggests that while being significantly activated, the hemodynamic responses of these brain regions could have been suppressed by the stimulus resulting in an intensity decrease with increasing neural efficacy.
    Matched MeSH terms: Noise
  16. Textitis as Seen on 18F-NaF Imaging Using an Ultra-High-Resolution Positron Emission Mammography Scanner
    Usmani S, Rasheed R, Al Kandari F
    J Nucl Med Technol, 2020 Jun;48(2):181-183.
    PMID: 32111663 DOI: 10.2967/jnmt.119.235986
    Textitis is a new term used to refer to the degenerative-strain osteoarthritis that comes from excessive use of a smart phone. 18F-NaF is increasingly used in diagnosing skeletal pain that is not identified on radiographs. We report a case of a 26-y-old woman with left breast cancer referred for 18F-NaF PET/CT, who was complaining of right thumb and wrist pain. Findings were negative for bone secondaries. Dedicated hands views were acquired on a positron emission mammography scanner and showed focal uptake at the first carpometacarpal and second metacarpophalangeal joints. On the basis of the strong history, the findings were likely due to active arthritic changes caused by repetitive strain injury from excessive text messaging.
    Matched MeSH terms: Signal-To-Noise Ratio*
  17. Characteristics of multiwavelength L-band Brillouin-Raman fiber laser under forward and backward pumped environment
    Abass AK, Al-Mansoori MH, Jamaludin MZ, Abdullah F, Al-Mashhadani TF
    Appl Opt, 2013 Jun 1;52(16):3764-9.
    PMID: 23736332 DOI: 10.1364/AO.52.003764
    We experimentally investigate the performance of L-band multiwavelength Brillouin-Raman fiber laser (MBRFL) under forward and backward pumped environments utilizing a linear cavity. A short length of 1.18 km dispersion compensating fiber is used as a nonlinear gain medium for both Brillouin and Raman gain. Experimental results indicate that the gain in the copumped laser configuration is higher than the gain in the counterpumped configuration. A stable and constant number of Brillouin Stokes lines up to 23 Stokes, with channel spacing of 0.08 nm and more than 20 dB of optical signal to noise ratio, can be generated as well as tuning over 20 nm in the L-band region from 1570 to 1590 nm. The laser generating the Brillouin Stokes lines exhibits flat amplitude bandwidth and high average output power of 0.8 and 1.6 dBm for the copropagation and counterpropagation pumps, respectively. Moreover, the tuning range bandwidth of the MBRFL can be predicted from the oscillated Brillouin pump gain profile.
    Matched MeSH terms: Signal-To-Noise Ratio
  18. Fulltext Tualang honey improves memory performance and decreases depressive-like behavior in rats exposed to loud noise stress
    Azman KF, Zakaria R, AbdAziz C, Othman Z, Al-Rahbi B
    Noise Health, 2015 Mar-Apr;17(75):83-9.
    PMID: 25774610 DOI: 10.4103/1463-1741.153388
    Recent evidence has exhibited dietary influence on the manifestation of different types of behavior induced by stressor tasks. The present study examined the effects of Tualang honey supplement administered with the goal of preventing or attenuating the occurrence of stress-related behaviors in male rats subjected to noise stress. Forty-eight adult male rats were randomly divided into the following four groups: i) nonstressed with vehicle, ii) nonstressed with Tualang honey, iii) stressed with vehicle, and iv) stressed with honey. The supplement was given once daily via oral gavage at 0.2 g/kg body weight. Two types of behavioral tests were performed, namely, the novel object recognition test to evaluate working memory and the forced swimming test to evaluate depressive-like behavior. Data were analyzed by a two-way analysis of variance (ANOVA) using IBM SPSS 18.0. It was observed that the rats subjected to noise stress expressed higher levels of depressive-like behavior and lower memory functions compared to the unexposed control rats. In addition, our results indicated that the supplementation regimen successfully counteracted the effects of noise stress. The forced swimming test indicated that climbing and swimming times were significantly increased and immobility times significantly decreased in honey-supplemented rats, thereby demonstrating an antidepressant-like effect. Furthermore, cognitive function was shown to be intensely affected by noise stress, but the effects were counteracted by the honey supplement. These findings suggest that subchronic exposure to noise stress induces depressive-like behavior and reduces cognitive functions, and that these effects can be attenuated by Tualang honey supplementation. This warrants further studies to examine the role of Tulang honey in mediating such effects.
    Matched MeSH terms: Noise*
  19. Fulltext A novel sample based quadrature phase shift keying demodulator
    Mohamed Moubark A, Ali SH
    ScientificWorldJournal, 2014;2014:107831.
    PMID: 25197687 DOI: 10.1155/2014/107831
    This paper presents a new practical QPSK receiver that uses digitized samples of incoming QPSK analog signal to determine the phase of the QPSK symbol. The proposed technique is more robust to phase noise and consumes up to 89.6% less power for signal detection in demodulation operation. On the contrary, the conventional QPSK demodulation process where it uses coherent detection technique requires the exact incoming signal frequency; thus, any variation in the frequency of the local oscillator or incoming signal will cause phase noise. A software simulation of the proposed design was successfully carried out using MATLAB Simulink software platform. In the conventional system, at least 10 dB signal to noise ratio (SNR) is required to achieve the bit error rate (BER) of 10(-6), whereas, in the proposed technique, the same BER value can be achieved with only 5 dB SNR. Since some of the power consuming elements such as voltage control oscillator (VCO), mixer, and low pass filter (LPF) are no longer needed, the proposed QPSK demodulator will consume almost 68.8% to 99.6% less operational power compared to conventional QPSK demodulator.
    Matched MeSH terms: Signal-To-Noise Ratio
  20. Fulltext Improving the dynamic characteristics of body-in-white structure using structural optimization
    Yahaya Rashid AS, Ramli R, Mohamed Haris S, Alias A
    ScientificWorldJournal, 2014;2014:190214.
    PMID: 25101312 DOI: 10.1155/2014/190214
    The dynamic behavior of a body-in-white (BIW) structure has significant influence on the noise, vibration, and harshness (NVH) and crashworthiness of a car. Therefore, by improving the dynamic characteristics of BIW, problems and failures associated with resonance and fatigue can be prevented. The design objectives attempt to improve the existing torsion and bending modes by using structural optimization subjected to dynamic load without compromising other factors such as mass and stiffness of the structure. The natural frequency of the design was modified by identifying and reinforcing the structure at critical locations. These crucial points are first identified by topology optimization using mass and natural frequencies as the design variables. The individual components obtained from the analysis go through a size optimization step to find their target thickness of the structure. The thickness of affected regions of the components will be modified according to the analysis. The results of both optimization steps suggest several design modifications to achieve the target vibration specifications without compromising the stiffness of the structure. A method of combining both optimization approaches is proposed to improve the design modification process.
    Matched MeSH terms: Noise*
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