Displaying publications 1 - 20 of 888 in total

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  1. Zhang G, Jing W, Tao H, Rahman MA, Salih SQ, Al-Saffar A, et al.
    Work, 2021;68(3):935-943.
    PMID: 33612535 DOI: 10.3233/WOR-203427
    BACKGROUND: Human-Robot Interaction (HRI) has become a prominent solution to improve the robustness of real-time service provisioning through assisted functions for day-to-day activities. The application of the robotic system in security services helps to improve the precision of event detection and environmental monitoring with ease.

    OBJECTIVES: This paper discusses activity detection and analysis (ADA) using security robots in workplaces. The application scenario of this method relies on processing image and sensor data for event and activity detection. The events that are detected are classified for its abnormality based on the analysis performed using the sensor and image data operated using a convolution neural network. This method aims to improve the accuracy of detection by mitigating the deviations that are classified in different levels of the convolution process.

    RESULTS: The differences are identified based on independent data correlation and information processing. The performance of the proposed method is verified for the three human activities, such as standing, walking, and running, as detected using the images and sensor dataset.

    CONCLUSION: The results are compared with the existing method for metrics accuracy, classification time, and recall.

    Matched MeSH terms: Environmental Monitoring
  2. Yusoff FA, Rahman RA, May LH, Budart SB, Sulaiman LH
    Western Pac Surveill Response J, 2015 May 27;6(2):27-31.
    PMID: 26306213 DOI: 10.5365/WPSAR.2015.6.1.012
    In September 2012, 10 cases suspected to be hepatitis A were notified to the Manjung District Health Department. An investigation was conducted to identify the possible mode of transmission, source of the outbreak and to recommend prevention and control measures.
    Matched MeSH terms: Environmental Monitoring
  3. Chow MF, Yusop Z
    Water Sci Technol, 2014;69(2):244-52.
    PMID: 24473291 DOI: 10.2166/wst.2013.574
    The characteristics of urban stormwater pollution in the tropics are still poorly understood. This issue is crucial to the tropical environment because its rainfall and runoff generation processes are so different from temperate regions. In this regard, a stormwater monitoring program was carried out at three urban catchments (e.g. residential, commercial and industrial) in the southern part of Peninsular Malaysia. A total of 51 storm events were collected at these three catchments. Samples were analyzed for total suspended solids, 5-day biochemical oxygen demand, chemical oxygen demand (COD), oil and grease, nitrate nitrogen, nitrite nitrogen, ammonia nitrogen (NH3-N), soluble reactive phosphorus and total phosphorus. Principal component analysis (PCA) and hierarchical cluster analysis were used to interpret the stormwater quality data for pattern recognition and identification of possible sources. The most likely sources of stormwater pollutants at the residential catchment were from surface soil and leachate of fertilizer from domestic lawns and gardens, whereas the most likely sources for the commercial catchment were from discharges of food waste and washing detergent. In the industrial catchment, the major sources of pollutants were discharges from workshops and factories. The PCA factors further revealed that COD and NH3-N were the major pollutants influencing the runoff quality in all three catchments.
    Matched MeSH terms: Environmental Monitoring/methods*
  4. Chow MF, Yusop Z, Mohamed M
    Water Sci Technol, 2011;63(6):1211-6.
    PMID: 21436558 DOI: 10.2166/wst.2011.360
    This paper examines the storm runoff quality from a commercial area in south Johor, Malaysia. Six storm events with a total of 68 storm runoff samples were analyzed. Event Mean Concentration (EMC) for all constituents analysed showed large inter-event variation. Site mean concentrations (SMC) for total suspended solids (TSS), oil and grease (O&G), biochemical oxygen demand (BOD), chemical oxygen demand (COD), nitrate-nitrogen (NO(3)-N), nitrite-nitrogen (NO(2)-N), ammonia-nitrogen (NH(3)-N), total phosphorus (Total P) and Soluble P are 261, 4.31, 74, 192, 1.5, 0.006, 1.9, 1.12 and 0.38 mg/L, respectively. The SMCs at the studied site are higher than those reported in many urban catchments. The mean baseflow concentrations were higher than the EMCs for COD, Soluble P, NH(3)-N, NO(3)-N, Total P and NO(2)-N. However, the reverse was observed for TSS and O&G. All pollutants showed the occurrence of first flush phenomenon with the highest strength was observed for TSS, COD and NH(3)-N.
    Matched MeSH terms: Environmental Monitoring
  5. Ayub KR, Zakaria NA, Abdullah R, Ramli R
    Water Sci Technol, 2010;62(8):1931-6.
    PMID: 20962410 DOI: 10.2166/wst.2010.473
    The Bio-ecological Drainage System, or BIOECODS, is an urban drainage system located at the Engineering Campus, Universiti Sains Malaysia. It consists of a constructed wetland as a part of the urban drainage system to carry storm water in a closed system. In this closed system, the constructed wetland was designed particularly for further treatment of storm water. For the purpose of studying the water balance of the constructed wetland, data collection was carried out for two years (2007 and 2009). The results show that the constructed wetland has a consistent volume of water storage compared to the outflow for both years with correlation coefficients (R(2)) of 0.99 in 2007 and 0.86 in 2009.
    Matched MeSH terms: Environmental Monitoring/methods*
  6. Nazahiyah R, Yusop Z, Abustan I
    Water Sci Technol, 2007;56(7):1-9.
    PMID: 17951862
    Sampling of urban runoff was carried out in a small catchment, which represents a residential area (3.34 ha) in Skudai, Johor. One hundred and seventeen runoff samples from ten storm events were analysed. Runoff quality showed large variations in concentrations during storms, especially for SS, BOD5 and COD. Concentrations of NO3-N, NO2-N, NH3-N, and P were also high. Lead (Pb) was also detected but the levels were low (<0.001 mg/L). In general, the river quality is badly polluted and falls in Class V based on the Malaysian Interim National Water Quality Standards. Event mean concentrations for all parameters were found to vary greatly between storms. The values (mg/L) were BOD5 (72), COD (325), SS (386), NO3-N (2.5), NO2-N (0.58), NH3-N (6.8), P (3.4), respectively. First flush phenomena were observed for BOD, COD, SS, NO3-N, NH3-N and P. The first 20-30% of the runoff volume evacuated between 20-59% BOD, 15-69% COD, 15-78% SS, 14-49% NO3-N, 14-19% NO2-N, 23-53% NH3-N and 23-43% P.
    Matched MeSH terms: Environmental Monitoring
  7. Yusop Z, Tan LW, Ujang Z, Mohamed M, Nasir KA
    Water Sci Technol, 2005;52(9):125-32.
    PMID: 16445181
    Runoff quality draining from 17.14 km2 urban catchment in Johor Bahru, Malaysia, was analysed. The land-use consists of residential (30.3%), agricultural (27.3%), open space (27.9%), industrial (8.1%) and commercial (6.4%) areas. Three storm events were sampled in detail. These storms produced stormflow between 0.84 mm and 27.82 mm, and peakflow from 2.19 m3/s to 42.36 m3/s. Water quality showed marked variation during storms especially for TSS, BOD and COD with maximum concentrations of 778 mg/l, 135 mg/l and 358 mg/l, respectively. Concentrations of TOC, DOC, NH3-N, Fe and level of colour were also high. In general, the river quality is badly polluted and falls in Class V based on the Malaysian Interim National Water Quality Standards. Event Mean Concentrations (EMC) for various parameters varied considerably between storms. The largest storm produced higher EMC for TSS, NO3-N and SS whereas the smaller storms tend to register higher EMC for BOD, COD, NH3-N, TOC, Ca, K, Mg, Fe and Zn. Such variations could be explained in terms of pollutant availability and the effects of flushing and dilution. Based on a three-month average recurrence interval (ARI) of rainfall, the estimated event loadings (ton/ha) of TSS, BOD, COD, TOC, NH3-N and NO3-N were 0.055, 0.016, 0.012, 0.039, 0.010, 0.0007 and 0.0002, respectively. Heavy metals present in trace quantities. Storms with 3 months ARI could capture about 70% of the total annual loads of major pollutants.
    Matched MeSH terms: Environmental Monitoring
  8. Ahmad UK, Ujang Z, Woon CH, Indran S, Mian MN
    Water Sci Technol, 2004;50(9):137-44.
    PMID: 15581005
    Land application of sludge as fertilizers is a way of disposal and recycling of sludge. However, public concern has arisen due to the fact that organic contaminants in sludge may ultimately enter the food chain. Hence the need arises to analyse the organic contaminants such as PAHs and OCPs in sludge. In this study, Soxhlet was utilised as the extraction method and the extracts subjected to extensive cleanup via either silica columns or solid phase extraction cartridges prior to analysis using gas chromatography or high performance liquid chromatography. Sludge samples were collected from the drying beds of oxidation ponds in three locations in South Johore. OCPs such as heptachlor, dieldrin and pp-DDT were detected in low amounts (52-159 mg/kg) whereas PAHs such as naphthalene, phenanthrene, fluoranthene and benzo(a)pyrene were detected in the range of 0.2-5.5 mg/kg dry mass. Subcritical water extraction (SWE) recovery studies of PAHs were also performed from spiked sludge samples. Although a recovery range of 41-68% was obtained using the SWE method, the results indicated the usefulness of the technique as an alternative to Soxhlet extraction for the analysis of PAHs in sludge samples.
    Matched MeSH terms: Environmental Monitoring
  9. Obaid HA, Shahid S, Basim KN, Chelliapan S
    Water Sci Technol, 2015;72(6):1029-42.
    PMID: 26360765 DOI: 10.2166/wst.2015.297
    Water pollution during festival periods is a major problem in all festival cities across the world. Reliable prediction of water pollution is essential in festival cities for sewer and wastewater management in order to ensure public health and a clean environment. This article aims to model the biological oxygen demand (BOD(5)), and total suspended solids (TSS) parameters in wastewater in the sewer networks of Karbala city center during festival and rainy days using structural equation modeling and multiple linear regression analysis methods. For this purpose, 34 years (1980-2014) of rainfall, temperature and sewer flow data during festival periods in the study area were collected, processed, and employed. The results show that the TSS concentration increases by 26-46 mg/l while BOD(5) concentration rises by 9-19 mg/l for an increase of rainfall by 1 mm during festival periods. It was also found that BOD(5) concentration rises by 4-17 mg/l for each increase of 10,000 population.
    Matched MeSH terms: Environmental Monitoring/methods*
  10. Le-Clech P, Alvarez-Vazquez H, Jefferson B, Judd S
    Water Sci Technol, 2003;48(3):113-9.
    PMID: 14518862
    As with all membrane processes, turbulence, as promoted by aeration in submerged membrane bioreactors (MBRs) or pumping in sidestream (SS) systems to produce somewhat higher effective cross-flow velocities, increases mass transfer and reduces fouling. This is manifested in an elevated critical flux, the flux at which the membrane permeability is sustained. However, the non-Newtonian nature of the sludge makes precise rheological characterisation difficult. In this study, a calculation of the appropriate hydrodynamics parameters for a SS MBR configuration is presented. Optimisation of the aeration in a submerged MBR system has been attained by defining the minimum air velocity required for Taylor bubble formation.
    Matched MeSH terms: Environmental Monitoring
  11. Zain SM, Basri H, Suja F, Jaafar O
    Water Sci Technol, 2002;46(9):303-8.
    PMID: 12448482
    Some of the major concerns when applying sewage sludge to land include the potential effect on pH and cation exchange capacity; the mobility and the accumulation of heavy metals in sludge treated soil; the potential of applying too much nutrients and the problems associated with odors and insects. The main objective of this study is to identify the effects of sewage sludge application on the physical and chemical properties of sludge treated soil. Sewage sludge was applied to soil at various rates ranging from 0 L/m2 to 341 L/m2. In order to simulate the natural environment, the study was carried out at a pilot treatment site (5.2 m x 6.7 m) in an open area, covered with transparent roofing material to allow natural sunlight to pass through. Simulated rain was applied by means of a sprinkler system. Data obtained from sludge treated soil showed that the pH values decreased when the application rates were increased and the application period prolonged. The effect of sewage sludge on cation exchange capacity was not so clear; the values obtained for every application rate of sewage sludge did not indicate any consistent behaviour. The mobility of heavy metals in soils treated with sludge were described by observing the changes in the concentration of the heavy metals. The study showed that Cd has the highest mobility in sludge treated soil followed by Cu, Cr, Zn, Ni and Pb.
    Matched MeSH terms: Environmental Monitoring
  12. Ahmad UK, Ulang Z, Yusop Z, Fong TL
    Water Sci Technol, 2002;46(9):117-25.
    PMID: 12448460
    The complex nature of natural organic matter (NOM), and the impact of this matter on drinking water quality have necessitated the characterization studies of NOM. A fluorescence technique for the characterization of NOM in Malaysian river water is reported. Water samples from several river sampling sites were collected and concentrated using a low-pressure reverse osmosis (LPROM). Solid phase extraction (SPE) using C18 extraction cartridges were used to fractionate the water samples into humic and non-humic fractions. To differentiate and classify various types of humic substances, fluorescence was applied in emission, excitation and in synchronous-scan modes. A synchronous spectral profile was found to be able to differentiate humic and fulvic acids better than the emission or excitation spectra. Synchronous excitation spectra showed different spectral patterns for the water samples due to different origin. All water samples showed the presence of both fulvic and humic acids.
    Matched MeSH terms: Environmental Monitoring/methods*
  13. Zalina MD, Desa MN, Nguyen VT, Kassim AH
    Water Sci Technol, 2002;45(2):63-8.
    PMID: 11890166
    This paper discusses the comparative assessment of eight candidate distributions in providing accurate and reliable maximum rainfall estimates for Malaysia. The models considered were the Gamma, Generalised Normal, Generalised Pareto, Generalised Extreme Value, Gumbel, Log Pearson Type III, Pearson Type III and Wakeby. Annual maximum rainfall series for one-hour resolution from a network of seventeen automatic gauging stations located throughout Peninsular Malaysia were selected for this study. The length of rainfall records varies from twenty-three to twenty-eight years. Model parameters were estimated using the L-moment method. The quantitative assessment of the descriptive ability of each model was based on the Probability Plot Correlation Coefficient test combined with root mean squared error, relative root mean squared error and maximum absolute deviation. Bootstrap resampling was employed to investigate the extrapolative ability of each distribution. On the basis of these comparisons, it can be concluded that the GEV distribution is the most appropriate distribution for describing the annual maximum rainfall series in Malaysia.
    Matched MeSH terms: Environmental Monitoring
  14. Bong CH, Lau TL, Ab Ghani A, Chan NW
    Water Sci Technol, 2016 Oct;74(8):1876-1884.
    PMID: 27789888
    The understanding of how the sediment deposit thickness influences the incipient motion characteristic is still lacking in the literature. Hence, the current study aims to determine the effect of sediment deposition thickness on the critical velocity for incipient motion. An incipient motion experiment was conducted in a rigid boundary rectangular flume of 0.6 m width with varying sediment deposition thickness. Findings from the experiment revealed that the densimetric Froude number has a logarithmic relationship with both the thickness ratios ts/d and ts/y0 (ts: sediment deposit thickness; d: grain size; y0: normal flow depth). Multiple linear regression analysis was performed using the data from the current study to develop a new critical velocity equation by incorporating thickness ratios into the equation. The new equation can be used to predict critical velocity for incipient motion for both loose and rigid boundary conditions. The new critical velocity equation is an attempt toward unifying the equations for both rigid and loose boundary conditions.
    Matched MeSH terms: Environmental Monitoring/methods*
  15. Ali MM, Ali ML, Islam MS, Rahman MZ
    Water Sci Technol, 2018 Mar;77(5-6):1418-1430.
    PMID: 29528329 DOI: 10.2166/wst.2018.016
    This study was conducted to assess the levels of toxic metals like arsenic (As), chromium (Cr), cadmium (Cd), and lead (Pb) in water and sediments of the Pasur River in Bangladesh. The ranges of Cr, As, Cd, Pb in water were 25.76-77.39, 2.76-16.73, 0.42-2.98 and 12.69-42.67 μg/L and in sediments were 20.67-83.70, 3.15-19.97, 0.39-3.17 and 7.34-55.32 mg/kg. The level of studied metals in water samples exceeded the safe limits of drinking water, indicating that water from this river is not safe for drinking and cooking. Certain indices, including pollution load index (PLI) and contamination factor (Cif) were used to assess the ecological risk. The PLI indicated progressive deterioration of sediments by the studied metals. Potential ecological risks of metals in sediment indicated low to considerable risk. However, the Cif values of Cd ranged from 0.86 to 8.37 revealed that the examined sediments were strongly impacted by Cd. Considering the severity of potential ecological risk (PER) for single metal (Eir), the descending order of contaminants was Cd > Pb > As > Cr. According the results, some treatment scheme must formulate and implement by the researchers and related management organizations to save the Pasur River from metals contamination.
    Matched MeSH terms: Environmental Monitoring*
  16. Saim N, Osman R, Sari Abg Spian DR, Jaafar MZ, Juahir H, Abdullah MP, et al.
    Water Res, 2009 Dec;43(20):5023-30.
    PMID: 19896157 DOI: 10.1016/j.watres.2009.08.052
    Faecal sterols detection is a promising method for identifying sources of faecal pollution. In this study, faecal contamination in water samples from point source (sewage treatment plants, chicken farms, quail farms and horse stables) was extracted using the solid phase extraction (SPE) technique. Faecal sterols (coprostanol, cholesterol, stigmasterol, beta-sitosterol and stigmastanol) were selected as parameters to differentiate the source of faecal pollution. The results indicated that coprostanol, cholesterol and beta-sitosterol were the most significant parameters that can be used as source tracers for faecal contamination. Chemometric techniques, such as cluster analysis, principal component analysis and discriminant analysis were applied to the data set on faecal contamination in water from various pollution sources in order to validate the faecal sterols' profiles. Cluster analysis generated three clusters: coprostanol was in cluster 1, cholesterol and beta-sitosterol formed cluster 2, while cluster 3 contained stigmasterol and stigmastanol. Discriminant analysis suggested that coprostanol, cholesterol and beta-sitosterol were the most significant parameters to discriminate between the faecal pollution source. The use of chemometric techniques provides useful and promising indicators in tracing the source of faecal contamination.
    Matched MeSH terms: Environmental Monitoring/methods
  17. Lee CW, Ng AY, Bong CW, Narayanan K, Sim EU, Ng CC
    Water Res, 2011 Feb;45(4):1561-70.
    PMID: 21146847 DOI: 10.1016/j.watres.2010.11.025
    Using the size fractionation method, we measured the decay rates of Escherichia coli, Salmonella Typhi and Vibrio parahaemolyticus in the coastal waters of Peninsular Malaysia. The size fractions were total or unfiltered, <250 μm, <20 μm, <2 μm, <0.7 μm, <0.2 μm and <0.02 μm. We also carried out abiotic (inorganic nutrients) and biotic (bacterial abundance, production and protistan bacterivory) measurements at Port Dickson, Klang and Kuantan. Klang had highest nutrient concentrations whereas both bacterial production and protistan bacterivory rates were highest at Kuantan. We observed signs of protist-bacteria coupling via the following correlations: Protistan bacterivory-Bacterial Production: r = 0.773, df = 11, p < 0.01; Protist-Bacteria: r = 0.586, df = 12, p < 0.05. However none of the bacterial decay rates were correlated with the biotic variables measured. E. coli and Salmonella decay rates were generally higher in the larger fraction (>0.7 μm) than in the smaller fraction (<0.7 μm) suggesting the more important role played by protists. E. coli and Salmonella also decreased in the <0.02 μm fraction and suggested that these non-halophilic bacteria did not survive well in seawater. In contrast, Vibrio grew well in seawater. There was usually an increase in Vibrio after one day incubation. Our results confirmed that decay or loss rates of E. coli did not match that of Vibrio, and also did not correlate with Salmonella decay rates. However E. coli showed persistence where its decay rates were generally lower than Salmonella.
    Matched MeSH terms: Environmental Monitoring
  18. Isobe KO, Zakaria MP, Chiem NH, Minh le Y, Prudente M, Boonyatumanond R, et al.
    Water Res, 2004 May;38(9):2448-58.
    PMID: 15142807
    This paper reports the result of sewage pollution monitoring conducted in South and Southeast Asia during 1998-2003 using linear alkylbenzenes (LABs) as molecular tracers of sewage contamination. Eighty-nine water samples collected from Malaysia, Vietnam, and Japan (Tokyo), and 161 surface sediment samples collected from Tokyo, Thailand, Malaysia, Philippines, Vietnam, Cambodia, Indonesia, and India were analyzed for alkylbenzenes. The concentration range of SigmaLABs in river water particles in Southeast Asia (<0.005-0.913 microg/L) was comparable to or higher than those found in Tokyo (<0.005-0.638 microg/L). I/E ratios (a ratio of internal to external isomers of LABs) in tropical Asian waters were close to the value of LABs in raw sewage ( approximately 1) and much lower than those in secondary effluents (3-5). This suggests that untreated or inadequately treated sewage is discharged into the water. SigmaLABs concentrations in sediments from South and Southeast Asia ranged from <0.002-42.6 microg/g-dry with the highest concentration occurring at several populous cities. Low I/E ratios of the sediments with high SigmaLABs concentrations suggest a heavy load of untreated sewage. Clearly in view of the current data and evidence of the implications of sewage pollution, this paper highlights the necessity of the continuation of water treatment system improvement in tropical Asia.
    Matched MeSH terms: Environmental Monitoring*
  19. Abdullah MP, Yew CH, Ramli MS
    Water Res, 2003 Nov;37(19):4637-44.
    PMID: 14568050
    A modeling procedure that predicts trihalomethane (THM) formation from field sampling at the treatment plant and along its distribution system using Tampin district, Negeri Sembilan and Sabak Bernam district, Selangor as sources of data were studied and developed. Using Pearson method of correlation, the organic matter measured as TOC showed a positive correlation with formation of THM (r=0.380,P=0.0001 for Tampin and r=0.478,P=0.0001 for Sabak Bernam). Similar positive correlation was also obtained for pH in both districts with Tampin (r=0.362,P=0.0010) and Sabak Bernam (r=0.215,P=0.0010). Chlorine dosage was also found to have low correlation with formation of THM for the two districts with Tampin (r=0.233,P=0.0230) and Sabak Bernam (r=0.505,P=0.0001). Distance from treatment plant was found to have correlation with formation of THM for Tampin district with r=0.353 and P=0.0010. Other parameters such as turbidity, ammonia, temperature and residue chlorine were found to have no correlation with formation of THM. Linear and non-linear models were developed for these two districts. The results obtained were validated using three different sets of field data obtained from own source and district of Seremban (Pantai and Sg. Terip), Negeri Sembilan. Validation results indicated that there was significant difference in the predictive and determined values of THM when two sets of data from districts of Seremban were used with an exception of field data of Sg. Terip for non-linear model developed for district of Tampin. It was found that a non-linear model is slightly better than linear model in terms of percentage prediction errors. The models developed were site specific and the predictive capabilities in the distribution systems vary with different environmental conditions.
    Matched MeSH terms: Environmental Monitoring
  20. Rasul MG, Islam MS, Yunus RBM, Mokhtar MB, Alam L, Yahaya FM
    Water Environ Res, 2017 Dec 01;89(12):2088-2102.
    PMID: 28087920 DOI: 10.2175/106143017X14839994522740
      The spatio-temporal variability of water quality associated with anthropogenic activities was studied for the Bertam River and its main tributaries within the Bertam Catchment, Cameron Highlands, Malaysia. A number of physico-chemical parameters of collected samples were analyzed to evaluate their spatio-temporal variability. Nonparametric statistical analysis showed significant temporal and spatial differences (p < 0.05) in most of the parameters across the catchment. Parameters except dissolved oxygen and chemical oxygen demand displayed higher values in rainy season. The higher concentration of total suspended solids was caused by massive soil erosion and sedimentation. Seasonal variations in contaminant concentrations are largely affected by precipitation and anthropogenic influences. Untreated domestic wastewater discharge as well as agricultural runoff significantly influenced the water quality. Poor agricultural practices and development activities at slope areas also affected the water quality within the catchment. The analytical results provided a basis for protection of river environments and ecological restoration in mountainous Bertam Catchment.
    Matched MeSH terms: Environmental Monitoring
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