Search results for: geological hazard

Authors: E. O. Okan, A. Kepic, P. Williams

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Iron oxide copper gold (IOCG) deposits constitute important sources of copper and gold in Australia especially since the discovery of the supergiant Olympic Dam deposits in 1975. They are considered to be metasomatic expressions of large crustal-scale alteration events occasioned by intrusive actions and are associated with felsic igneous rocks in most cases, commonly potassic igneous magmatism, with the deposits ranging from ~2.2 –1.5 Ga in age. For the past two decades, geological, geochemical and potential methods have been used to identify the structures hosting these deposits follow up by drilling. Though these methods have largely been successful for shallow targets, at deeper depth due to low resolution they are limited to mapping only very large to gigantic deposits with sufficient contrast. As the search for ore-bodies under regolith cover continues due to depletion of the near surface deposits, there is a compelling need to develop new exploration technology to explore these deep seated ore-bodies within 1-4km which is the current mining depth range. Seismic reflection method represents this new technology as it offers a distinct advantage over all other geophysical techniques because of its great depth of penetration and superior spatial resolution maintained with depth. Further, in many different geological scenarios, it offers a greater ‘3D mapability’ of units within the stratigraphic boundary. Despite these superior attributes, no arguments for crustal scale seismic surveys have been proposed because there has not been a compelling argument of economic benefit to proceed with such work. For the seismic reflection method to be used at these scales (100’s to 1000’s of square km covered) the technical risks or the survey costs have to be reduced. In addition, as most IOCG deposits have large footprint due to its association with intrusions and large fault zones; we hypothesized that these deposits can be found by mainly looking for the seismic signatures of intrusions along prospective structures. In this study, we present two of such cases: - Olympic Dam and Vulcan iron-oxide copper-gold (IOCG) deposits all located in the Gawler craton, South Australia. Results from our 2D modelling experiments revealed that seismic reflection surveys using 20m geophones and 40m shot spacing as an exploration tool for locating IOCG deposit is possible even when hosted in very complex structures. The migrated sections were not only able to identify and trace various layers plus the complex structures but also show reflections around the edges of intrusive packages. The presences of such intrusions were clearly detected from 100m to 1000m depth range without losing its resolution. The modelled seismic images match the available real seismic data and have the hypothesized characteristics; thus, the seismic method seems to be a valid exploration tool to find IOCG deposits. We therefore propose that 2D seismic survey is viable for IOCG exploration as it can detect mineralised intrusive structures along known favourable corridors. This would help in reducing the exploration risk associated with locating undiscovered resources as well as conducting a life-of-mine study which will enable better development decisions at the very beginning.

Keywords: crustal scale, exploration, IOCG deposit, modelling, seismic surveys

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Authors: Kamyar Tolouei, Ehsan Moosavi

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In open-pit mines, the long-term production scheduling optimization problem (LTPSOP) is a complicated problem that contains constraints, large datasets, and uncertainties. Uncertainty in the output is caused by several geological, economic, or technical factors. Due to its dimensions and NP-hard nature, it is usually difficult to find an ideal solution to the LTPSOP. The optimal schedule generally restricts the ore, metal, and waste tonnages, average grades, and cash flows of each period. Past decades have witnessed important measurements of long-term production scheduling and optimal algorithms since researchers have become highly cognizant of the issue. In fact, it is not possible to consider LTPSOP as a well-solved problem. Traditional production scheduling methods in open-pit mines apply an estimated orebody model to produce optimal schedules. The smoothing result of some geostatistical estimation procedures causes most of the mine schedules and production predictions to be unrealistic and imperfect. With the expansion of simulation procedures, the risks from grade uncertainty in ore reserves can be evaluated and organized through a set of equally probable orebody realizations. In this paper, to synthesize grade uncertainty into the strategic mine schedule, a stochastic integer programming framework is presented to LTPSOP. The objective function of the model is to maximize the net present value and minimize the risk of deviation from the production targets considering grade uncertainty simultaneously while satisfying all technical constraints and operational requirements. Instead of applying one estimated orebody model as input to optimize the production schedule, a set of equally probable orebody realizations are applied to synthesize grade uncertainty in the strategic mine schedule and to produce a more profitable and risk-based production schedule. A mixture of metaheuristic procedures and mathematical methods paves the way to achieve an appropriate solution. This paper introduced a hybrid model between the augmented Lagrangian relaxation (ALR) method and the metaheuristic algorithm, the Harris Hawks optimization (HHO), to solve the LTPSOP under grade uncertainty conditions. In this study, the HHO is experienced to update Lagrange coefficients. Besides, a machine learning method called Random Forest is applied to estimate gold grade in a mineral deposit. The Monte Carlo method is used as the simulation method with 20 realizations. The results specify that the progressive versions have been considerably developed in comparison with the traditional methods. The outcomes were also compared with the ALR-genetic algorithm and ALR-sub-gradient. To indicate the applicability of the model, a case study on an open-pit gold mining operation is implemented. The framework displays the capability to minimize risk and improvement in the expected net present value and financial profitability for LTPSOP. The framework could control geological risk more effectively than the traditional procedure considering grade uncertainty in the hybrid model framework.

Keywords: grade uncertainty, metaheuristic algorithms, open-pit mine, production scheduling optimization

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Authors: Dmitrii Glushkov, Aleksandr G. Nigay, Olga S. Yashutina

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In recent years, due to the intensive development of the Arctic and Antarctic areas, the actual task is to develop technology for the effective utilization of solid and liquid combustible wastes in an environment with low temperatures. Firstly, such technology will help to prevent the dumping of waste into the World Ocean and reduce the risks of causing environmental damage to the Far North areas. Secondly, promising actions will help to prepare fuel compositions from the waste in the places of their production. Such kind of fuels can be used as energy resources. It will reduce waste utilization costs when transporting them to the mainland. In the present study, we suggest a solution to the problem of waste utilization by the preparation of gel fuels based on solid and liquid combustible components with the addition of the thickener. Such kind of fuels is characterized by ease of preparation, storage, transportation and use (as energy resources). The main regularities and characteristics of physical and chemical processes are established with varying parameters of gel fuels and heating sources in wide ranges. The obtained results let us conclude about the prospects of gel fuels practical application for combustible wastes utilization. Appropriate technology will be characterized by positive environmental, operational and economic effects. The composition of the gel fuels can vary in a wide range. The fuels preparation based on one type of a combustible liquid or a several liquids mixture with the finely dispersed components addition makes it possible to obtain compositions with predicted rheological, energy or environmental characteristics. Besides, gel fuels have a lower level of the fire hazard compared to common solid and liquid fuels. This makes them convenient for storage and transportation. In such conditions, it is not necessary to transport combustible wastes from the territory of the Arctic and the Antarctic to the mainland for processing, which is now quite an expensive procedure. The research was funded by the Russian Science Foundation (project No. 18-13-00031).

Keywords: combustible liquid waste, gel fuel, ignition and combustion, utilization

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Authors: Sulaiman Rabiu, Muazu Gusau Abubakar, Jafar Usman Zakari

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The consumption of meat is of great importance as it provides a good source of proteins and significant amount of essential trace element to the body. However, contamination of meat and meat products with heavy metals is becoming a serious threat to food safety and public health. Therefore, the present study is aimed to evaluate the concentration of some heavy metals in muscles and entrails of free-ranged cattle, sheep and goats. A total of sixty (60) fresh samples of muscles, liver, kidney, small intestines and stomach of free ranged cattle, sheep and goats were collected from abattoirs of different goldmine communities of Anka, Bukkuyum, Maru andTalata-Mafara Local Government Areas of Zamfara State, Nigeria. The samples were digested using 10 mL of a mixed 70% high grade concentration of HNO₃ and 65% HCl (4:1 v/v); the mixture was heated until dense fumes disappeared forming a clear transparent solution and diluted to 50 mL with deionized water. Actual concentrations of Cd, Cr, Cu, Co, As, Ni, Mn, Pb and Zn were determined using Microwave Plasma Atomic Emission Spectrophotometer (MP-AES). From the results obtained, goat liver had the highest mean concentration of lead, arsenic, cobalt and manganese (12.43± 0.31, 14.25±0.32, 3.47± 0.86 and 12.68± 0.92 mg/kg respectively) while goat kidney had the highest concentration of copper and zinc (10.08±0.61 and 24.16±1.30 mg/kg respectively). The highest concentrations of cadmium and nickel were recorded in sheep kidney (7.75± 0.65 and 2.08±0.10 mg/kg respectively). Cattle muscles had the highest chromium concentration than all the organs analysed. The target hazard quotients (THQs) for all the metals were below 1.0, but TR which is a risk indices for carcinogenicity indicates an alarming result that requires stringent control to protect public health.Therefore, intensive public health awareness on the risk associated with contamination of heavy metals in meat should be advocated.

Keywords: contamination, goldmine, heavy metals, meat

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Authors: Nayab Kanwal, Noor Us Saher

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The management and utilization of food resources is becoming a big issue due to rapid urbanization, wastage and non-sustainable use of food, especially in developing countries. Therefore, the use of seafood as alternative sources is strongly promoted worldwide. Marine pollution strongly affects marine organisms, which ultimately decreases their export quality. The monitoring of contamination in marine organisms is a good indicator of the environmental quality as well as seafood quality. Monitoring the accumulation of chemical elements within various tissues of organisms has become a useful tool to survey current or chronic levels of heavy metal exposure within an environment. In this perspective, this study was carried out to compare the previous and current levels (Year 2012 and 2014) of heavy metals (Cd, Pb, Cr, Cu and Zn) in crabs marketed in Karachi and to estimate the toxicological risk associated with their intake. The accumulation of metals in marine organisms, both essential (Cu and Zn) and toxic (Pb, Cd and Cr), natural and anthropogenic, is an actual food safety issue. Significant (p>0.05) variations in metal concentrations were found in all crab species between the two years, with most of the metals showing high accumulation in 2012. For toxicological risk assessment, EWI (Estimated weekly intake), Target Hazard quotient (THQ) and cancer risk (CR) were also assessed and high EWI, Non- cancer risk (THQ < 1) showed that there is no serious threat associated with the consumption of shellfish species on Karachi coast. The Cancer risk showed the highest risk from Cd and Pb pollution if consumed in excess. We summarize key environmental health research on health effects associated with exposure to contaminated seafood. It could be concluded that considering the Pakistan coast, these edible species may be sensitive and vulnerable to the adverse effects of environmental contaminants; more attention should be paid to the Pb and Cd metal bioaccumulation and to toxicological risks to seafood and consumers.

Keywords: cancer risk, edible crabs, heavy metals pollution, risk assessment

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Authors: Wajeeha Zahid, Shafquat Rozi, Farhan Raza, Masood Kadir

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Background: Dental caries affects the overall health and well-being of children. Findings from various international studies regarding the association of dental caries with asthma are inconsistent. With the increasing burden of caries and childhood asthma, it becomes imperative for an underdeveloped country like Pakistan where resources are limited to identify whether there is a relationship between the two. This study aims to identify an association between dental caries and asthma. Methods: A cross-sectional study was conducted on 544 children aged 12-15 years recruited from five private schools in Karachi. Information on asthma was collected through the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire. The questionnaire addressed questions regarding child’s demographics, physician diagnoses of asthma, type of medication administered, family history of asthma and allergies, dietary habits and oral hygiene behavior. Dental caries was assessed using DMFT Index (Decayed, Missing, Filled teeth) index The data was analyzed using Cox proportional Hazard algorithm and crude and adjusted prevalence ratios with 95% CI were reported. Results: This study comprises of 306 (56.3%) boys and 238 (43.8%) girls. The mean age of children was 13.2 ± (0.05) years. The total number of children with carious teeth (DMFT > 0) were 166/544 (30.5%), and the decayed component contributed largely (22.8%) to the DMFT score. The prevalence of physician’s diagnosed asthma was 13%. This study identified almost 7% asthmatic children using the internationally validated International Study of Asthma and Allergies in Childhood (ISAAC) tool and 8 children with childhood asthma were identified by parent interviews. Overall prevalence of asthma was 109/544 (20%). The prevalence of caries in asthmatic children was 28.4% as compared to 31% among non-asthmatic children. The adjusted prevalence ratio of dental caries in asthmatic children was 0.8 (95% CI 0.59-1.29). After adjusting for carious food intake, age, oral hygiene index and dentist visit, the association between asthma and dental caries turned out to be non-significant. Conclusion: There was no association between asthma and dental caries among children who participated in this study.

Keywords: asthma, caries, children, school-based

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Authors: Anne C. Okwedadi, Samson Ng’ambi, Ian Jefferson

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Collapsible soils go through radical rearrangement of their particles when triggered by water, stress or/and vibration, causing loss of volume. This loss of volume in soil as seen in foundation failures has caused millions of dollars’ worth of damages to public facilities and infrastructure and so has an adverse effect on the society and people. Despite these consequences and the several studies that are available, more research is still required in the study of soil collapsibility. Discerning the pedogenesis (formation) of soils and investigating the combined effects of the different geological soil properties is key to elucidating and quantifying soils collapsibility. This study presents a novel laboratory testing regime that would be undertaken on soil samples where the effects of soil type, compactive variables (moisture content, density, void ratio, degree of saturation) and loading are analyzed. It is anticipated that results obtained would be useful in mapping the trend of the combined effect thus the basis for evaluating soil collapsibility or collapse potentials encountered in construction with volume loss problems attributed to collapse.

Keywords: collapsible soil, geomorphological process, soil collapsibility properties, soil test

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Authors: Naresh Kumar, Savita Kumari, Naresh Kochhar

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The objective of the study was to assess the role of mineralogy and subsurface structure on water quality of Tosham, Malani Igneous Suite (MIS), Western Rajasthan, India. MIS is the largest (55,000 km2) A-type, anorogenic and high heat producing acid magmatism in the peninsular India and owes its origin to hot spot tectonics. Apart from agricultural and industrial wastes, geogenic activities cause fluctuations in quality parameters of water resources. Twenty water samples (20) selected from Tosham and surrounding areas were analyzed for As, Pb, B, Al, Zn, Fe, Ni using Inductive coupled plasma emission and F by Ion Chromatography. The concentration of As, Pb, B, Ni and F was above the stipulated level specified by BIS (Bureau of Indian Standards IS-10500, 2012). The concentration of As and Pb in surrounding areas of Tosham ranged from 1.2 to 4.1 mg/l and from 0.59 to 0.9 mg/l respectively which is higher than limits of 0.05mg/l (As) and 0.01 mg/l (Pb). Excess trace metal accumulation in water is toxic to humans and adversely affects the central nervous system, kidneys, gastrointestinal tract, skin and cause mental confusion. Groundwater quality is defined by nature of rock formation, mineral water reaction, physiography, soils, environment, recharge and discharge conditions of the area. Fluoride content in groundwater is due to the solubility of fluoride-bearing minerals like fluorite, cryolite, topaz, and mica, etc. Tosham is comprised of quartz mica schist, quartzite, schorl, tuff, quartz porphyry and associated granites, thus, fluoride is leached out and dissolved in groundwater. In the study area, Ni concentration ranged from 0.07 to 0.5 mg/l (permissible limit 0.02 mg/l). The primary source of nickel in drinking water is leached out nickel from ore-bearing rocks. Higher concentration of As is found in some igneous rocks specifically containing minerals as arsenopyrite (AsFeS), realgar (AsS) and orpiment (As2S3). MIS consists of granite (hypersolvus and subsolvus), rhyolite, dacite, trachyte, andesite, pyroclasts, basalt, gabbro and dolerite which increased the trace elements concentration in groundwater. Nakora, a part of MIS rocks has high concentration of trace and rare earth elements (Ni, Rb, Pb, Sr, Y, Zr, Th, U, La, Ce, Nd, Eu and Yb) which percolates the Ni and Pb to groundwater by weathering, contacts and joints/fractures in rocks. Additionally, geological setting of MIS also causes dissolution of trace elements in water resources beneath the surface. NE–SW tectonic lineament, radial pattern of dykes and volcanic vent at Nakora created a way for leaching of these elements to groundwater. Rain water quality might be altered by major minerals constituents of host Tosham rocks during its percolation through the rock fracture, joints before becoming the integral part of groundwater aquifer. The weathering process like hydration, hydrolysis and solution might be the cause of change in water chemistry of particular area. These studies suggest that geological relation of soil-water horizon with MIS rocks via mineralogical variations, structures and tectonic setting affects the water quality of the studied area.

Keywords: geochemistry, groundwater, malani igneous suite, tosham

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Authors: Herng-Sheng Lee, Chi-Yi Chen, Wan-Ting Huang, Li-Jen Chang, Solomon Chih-Cheng Chen, Hsin-Yi Yang

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A variety of gastrointestinal disorders, such as Crohn’s disease, ulcerative colitis, and coeliac disease, are recognized as risk factors for osteoporosis and osteoporotic fractures. One recent study suggests that individuals with irritable bowel syndrome (IBS) might also be at increased risk of osteoporosis and osteoporotic fractures. Up to now, the association between IBS and the risk of fractures at different anatomic sites occurrences is not completely clear. We conducted a population-based cohort analysis to investigate the fracture risk of IBS in comparison with non-IBS group. We identified 29,505 adults aged ≥ 20 years with newly diagnosed IBS using the Taiwan National Health Insurance Research Database in 2000-2012. A comparison group was constructed of patients without IBS who were matched according to gender and age. The occurrence of fracture was monitored until the end of 2013. We analyzed the risk of fracture events to occur in IBS by using Cox proportional hazards regression models. Patients with IBS had a higher incidence of osteoporotic fractures compared with non-IBS group (12.34 versus 9.45 per 1,000 person-years) and an increased risk of osteoporotic fractures (adjusted hazard ratio [aHR] = 1.27, 95 % confidence interval [CI] = 1.20 – 1.35). Site specific analysis showed that the IBS group had a higher risk of fractures for spine, forearm, hip and hand than did the non-IBS group. With further stratification for gender and age, a higher aHR value for osteoporotic fractures in IBS group was seen across all age groups in males, but seen in elderly females. In addition, female, elderly, low income, hypertension, coronary artery disease, cerebrovascular disease, and depressive disorders as independent osteoporotic fracture risk factors in IBS patients. The IBS is considered as a risk factor for osteoporotic fractures, particularly in female individuals and fracture sites located at the spine, forearm, hip and hand.

Keywords: irritable bowel syndrome, fracture, gender difference, longitudinal health insurance database, public health

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Authors: Osayomwanbor E. Oghama, John O. Olomukoro

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The school environment, apart from home, is probably the most important indoor environment for children. Children spend as much as 80-90% of their indoor time either at school or at home; an average of 35 - 40 hours per week in schools, hence are at the risk of indoor air pollutants such as volatile organic compounds (VOCs). Concentrations of VOCs vary widely but are generally higher indoors than outdoors. This research was, therefore, carried out to evaluate the levels of VOCs in secondary school classrooms in Benin City, Edo State. Samples were obtained from a total of 18 classrooms in 6 secondary schools. Samples were collected 3 times from each school and from 3 different classrooms in each school using Draeger ORSA 5 tubes. Samplers were left to stay for a school-week (5 days). The VOCs detected and analyzed were benzene, ethlybenzene, isopropylbenzene, naphthalene, n-butylbenzene, n-propylbenzene, toluene, m-xylene, p-xylene, o-xylene, styrene, chlorobenzene, chloroform, 1,2-dichloropropane, 2,2-dichloropropane, tetrachloroethane, tetrahydrofuran, isopropyl acetate, α-pinene, and camphene. The results showed that chloroform, o-xylene, and styrene were the most abundant while α-pinene and camphene were the least abundant. The health risk assessment was done in terms of carcinogenic (CRI) and non-carcinogenic risks (THR). The CRI values of the schools ranged from 1.03 × 10-5 to 1.36 × 10-5 μg/m³ (a mean of 1.16 × 10-5 μg/m³) with School 6 and School 3 having the highest and lowest values respectively. The THR values of the study schools ranged from 0.071-0.086 μg/m³ (a mean of 0.078 μg/m³) with School 3 and School 2 having the highest and lowest values respectively. The results show that all the schools pose a potential carcinogenic risks having CRI values greater than the recommended limit of 1 × 10-6 µg/m³ and no non-carcinogenic risk having THR values less than the USEPA hazard quotient of 1 µg/m³. It is recommended that school authorities should ensure adequate ventilation in their schools, supplementing natural ventilation with mechanical sources, where necessary. In addition, indoor air quality should be taken into consideration in the design and construction of classrooms.

Keywords: carcinogenic risk indicator, health risk, indoor air, non-carcinogenic risk indicator, secondary schools, volatile organic compounds

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Authors: Esra Zengin, Sinan Akkar

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Reliable and accurate prediction of nonlinear structural response requires specification of appropriate earthquake ground motions to be used in nonlinear time history analysis. The current research has mainly focused on selection and manipulation of real earthquake records that can be seen as the most critical step in the performance based seismic design and assessment of the structures. Utilizing amplitude scaled ground motions that matches with the target spectra is commonly used technique for the estimation of nonlinear structural response. Representative ground motion ensembles are selected to match target spectrum such as scenario-based spectrum derived from ground motion prediction equations, Uniform Hazard Spectrum (UHS), Conditional Mean Spectrum (CMS) or Conditional Spectrum (CS). Different sets of criteria exist among those developed methodologies to select and scale ground motions with the objective of obtaining robust estimation of the structural performance. This study presents ground motion selection and scaling procedure that considers the spectral variability at target demand with the level of ground motion dispersion. The proposed methodology provides a set of ground motions whose response spectra match target median and corresponding variance within a specified period interval. The efficient and simple algorithm is used to assemble the ground motion sets. The scaling stage is based on the minimization of the error between scaled median and the target spectra where the dispersion of the earthquake shaking is preserved along the period interval. The impact of the spectral variability on nonlinear response distribution is investigated at the level of inelastic single degree of freedom systems. In order to see the effect of different selection and scaling methodologies on fragility curve estimations, results are compared with those obtained by CMS-based scaling methodology. The variability in fragility curves due to the consideration of dispersion in ground motion selection process is also examined.

Keywords: ground motion selection, scaling, uncertainty, fragility curve

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Authors: Fahad Alahmadi, Norhan Abd Rahman, Mohammad Abdulrazzak, Zulikifli Yusop

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Runoff prediction of ungauged catchment is still a challenging task especially in arid regions with a unique land cover such as volcanic basalt rocks where geological weathering and fractures are highly significant. In this study, Bathan catchment in Madinah western Saudi Arabia was selected for analysis. The aim of this paper is to evaluate different rainfall loss methods; soil conservation Services curve number (SCS-CN), green-ampt and initial-constant rate. Different direct runoff methods were evaluated: soil conservation services dimensionless unit hydrograph (SCS-UH), Snyder unit hydrograph and Clark unit hydrograph. The study showed the superiority of SCS-CN loss method and Clark unit hydrograph method for ungauged catchment where there is no observed runoff data.

Keywords: urban runoff modelling, arid regions, ungauged catchments, volcanic rocks, Madinah, Saudi Arabia

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Authors: Chiara Colarusso, Michela Terlizzi, Aldo Pinto, Rosalinda Sorrentino

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Cigarette smoking is the main cause and the most common risk factor for both COPD and lung cancer. In our previous studies, we proved that caspase-11 in mice and its human analogue, caspase-4, are involved in lung carcinogenesis and that AIM2 inflammasome might play a pro-cancerous role in lung cancer. Therefore, the aim of this study was to investigate potential crosstalk between COPD and lung cancer, focusing on AIM2 and caspase-11-dependent inflammasome signaling pathway. To mimic COPD, we took advantage of an experimental first-hand smoking mouse model and, to confirm what was observed in mice, we used human samples of lung adenocarcinoma patients stratified according to the smoking and COPD status. We demonstrated that smoke exposure led to emphysema-like features, bronchial tone impairment, and release of IL-1-like cytokines (IL-1α, IL-1β, IL-33, IL-18) in a caspase-1 independent manner in C57Bl/6N. Rather, a dysfunctional caspase-11 in smoke-exposed 129Sv mice was associated to lower bronchial inflammation, collagen deposition, and IL-1-like inflammation. In addition, for the first time, we found that AIM2 inflammasome is involved in lung inflammation in smoking and COPD, in that its expression was higher in smoke-exposed C57Bl/6N compared to 129Sv smoking mice, who instead did not show any alteration of AIM2 in both macrophages and dendritic cells. Moreover, we found that AIM2 expression in the cancerous tissue, albeit higher than non-cancerous tissue, was not statistically different according to the COPD and smoking status. Instead, the higher expression of AIM2 in non-cancerous tissue of smoker COPD patients than smokers who did not have COPD was correlated to a higher hazard ratio of poor survival rate than patients who presented lower levels of AIM2. In conclusion, our data highlight that caspase-11 in mice is associated to smoke-induced lung latent inflammation which could drive the establishment of lung cancer, and that AIM2 inflammasome plays a role at the crosstalk between smoking/COPD and lung adenocarcinoma in that its higher presence is correlated to lower survival rate of smoker COPD adenocarcinoma.

Keywords: COPD, inflammasome, lung cancer, lung inflammation, smoke

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Authors: Neha Devi, P. K. Joshi

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Fire fuel map is one of the most critical factors for planning and managing the fire hazard and risk. One of the most significant forms of global disturbance, impacting community dynamics, biogeochemical cycles and local and regional climate across a wide range of ecosystems ranging from boreal forests to tropical rainforest is wildfire Assessment of fire danger is a function of forest type, fuelwood stock volume, moisture content, degree of senescence and fire management strategy adopted in the ground. Remote sensing has potential of reduction the uncertainty in mapping fuels. Hyperspectral remote sensing is emerging to be a very promising technology for wildfire fuels characterization. Fine spectral information also facilitates mapping of biophysical and chemical information that is directly related to the quality of forest fire fuels including above ground live biomass, canopy moisture, etc. We used Hyperion imagery acquired in February, 2016 and analysed four fuel characteristics using Hyperion sensor data on-board EO-1 satellite, acquired over the Shiwalik Himalayas covering the area of Champawat, Uttarakhand state. The main objective of this study was to present an overview of methodologies for mapping fuel properties using hyperspectral remote sensing data. Fuel characteristics analysed include fuel biomass, fuel moisture, and fuel condition and fuel type. Fuel moisture and fuel biomass were assessed through the expression of the liquid water bands. Fuel condition and type was assessed using green vegetation, non-photosynthetic vegetation and soil as Endmember for spectral mixture analysis. Linear Spectral Unmixing, a partial spectral unmixing algorithm, was used to identify the spectral abundance of green vegetation, non-photosynthetic vegetation and soil.

Keywords: forest fire fuel, Hyperion, hyperspectral, linear spectral unmixing, spectral mixture analysis

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Authors: Xie Xiaobin, Zhang Yan, Shi Yipeng, Sun Wenying, Chen Shuang, Cai Zhipeng, Zhang Hong, Zhang Lixia, Xie Like

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Objective: The objective of this research is to compare the efficacy of the late in-situ surgical revision augmented with continuous infusion and needle revision on failed trabeculectomy blebs. Methods From December 2018 to December 2021, a prospective randomized controlled trial was performed on 44 glaucoma patients with failed bleb ≥ 6months with medically uncontrolled in Eye Hospital, China Academy of Chinese Medical Sciences. They were randomly divided into two groups. 22 eyes of 22 patients underwent the late in-situ surgical revision with continuous anterior chamber infusion in the study group, and 22 of 22 patients were treated with needle revision in the control group. Main outcome measures include preoperative and postoperative intraocular pressure (IOP), the number of anti-glaucoma medicines, the operation success rate, and the postoperative complications. Results The postoperative IOP values decreased significantly from the baseline in both groups (both P<0.05). IOP was significantly lower in the study group than in the control group at one week, 1, and 3 months postoperatively (all P<0.05). IOP reductions in the study group were substantially more prominent than in the control group at all postoperative time points (all P<0.05). The complete success rate in the study group was significantly higher than in the control group (71.4% vs. 33.3%, P<0.05), while the complete failure rate was significantly lower in the study group (0% vs. 28.5%, P<0.05). According to Cox’s proportional hazards regression analysis, high IOP at baseline was independently associated with increased risks of complete failure (adjusted hazard ratio=1.141, 95% confidence interval=1.021-1.276, P<0.05). There was no significant difference in the incidence of postoperative complications between the two groups (P>0.05). Conclusion: Both in-situ surgical and needle revision have acceptable success rates and safety for the late failed trabeculectomy blebs, while the former is likely to have a higher level of efficacy over the latter. Needle revision may be insufficient for eyes with low target IOP.

Keywords: glaucoma, trabeculectomy blebs, in-situ surgical revision, needle revision

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Authors: Nuo Xu, Kok Hun Goh, Jeyatharan Kumarasamy

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Pile load testing is significant during foundation construction due to its traditional role of design validation and routine quality control of the piling works. In order to verify whether piles can take loadings at specified settlements, piles will have to undergo working load test where the test load should normally up to 150% of the working load of a pile. Selection or sampling of piles for the working load test is done subject to the number specified in Singapore National Annex to Eurocode 7 SS EN 1997-1:2010. This paper presents an innovative way to rationalize the number of pile load test by adopting statistical analysis approach and looking at the coefficient of variance of pile elastic modulus using a case study at Singapore Tuas depot. Results are very promising and have shown that it is possible to reduce the number of working load test without influencing the reliability and confidence on the pile quality. Moving forward, it is suggested that more load test data from other geological formations to be examined to compare with the findings from this paper.

Keywords: elastic modulus of pile under soil interaction, jurong formation, kentledge test, pile load test

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Authors: Shivdayal Patel, Suhail Ahmad

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Safety assurance and failure prediction of composite material component of an offshore structure due to low velocity impact is essential for associated risk assessment. It is important to incorporate uncertainties associated with material properties and load due to an impact. Likelihood of this hazard causing a chain of failure events plays an important role in risk assessment. The material properties of composites mostly exhibit a scatter due to their in-homogeneity and anisotropic characteristics, brittleness of the matrix and fiber and manufacturing defects. In fact, the probability of occurrence of such a scenario is due to large uncertainties arising in the system. Probabilistic finite element analysis of composite plates due to low-velocity impact is carried out considering uncertainties of material properties and initial impact velocity. Impact-induced damage of composite plate is a probabilistic phenomenon due to a wide range of uncertainties arising in material and loading behavior. A typical failure crack initiates and propagates further into the interface causing de-lamination between dissimilar plies. Since individual crack in the ply is difficult to track. The progressive damage model is implemented in the FE code by a user-defined material subroutine (VUMAT) to overcome these problems. The limit state function is accordingly established while the stresses in the lamina are such that the limit state function (g(x)>0). The Gaussian process response surface method is presently adopted to determine the probability of failure. A comparative study is also carried out for different combination of impactor masses and velocities. The sensitivity based probabilistic design optimization procedure is investigated to achieve better strength and lighter weight of composite structures. Chain of failure events due to different modes of failure is considered to estimate the consequences of failure scenario. Frequencies of occurrence of specific impact hazards yield the expected risk due to economic loss.

Keywords: composites, damage propagation, low velocity impact, probability of failure, uncertainty modeling

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Authors: Menuka Maharjan

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In the name of food security, agriculture intensification through conventional farming is being implemented in Nepal. Government focus on increasing agriculture production completely ignores soil as well human health. This leads to create serious soil degradation, i.e., reduction of soil fertility and microbial activity and health hazard in the country. On this note, organic farming is sustainable agriculture approach which can address challenge of sustaining food security while protecting the environment. This creates a win-win situation both for people and the environment. However, people have limited knowledge on significance of organic farming for environment conservation and food security especially developing countries like Nepal. Thus, the objective of the study was to assess the impacts of organic farming on soil fertility and microbial activity compared to conventional farming and forest in Chitwan, Nepal. Total soil organic carbon (C) was highest in organic farming (24 mg C g⁻¹ soil) followed by conventional farming (15 mg C g⁻¹ soil) and forest (9 mg C g⁻¹ soil) in the topsoil layer (0-10 cm depth). A similar trend was found for total nitrogen (N) content in all three land uses with organic farming soil possessing the highest total N content in both 0-10 cm and 10-20 cm depth. Microbial biomass C and N were also highest under organic farming, especially in the topsoil layer (350 and 46 mg g⁻¹ soil, respectively). Similarly, microbial biomass phosphorus (P) was higher (3.6 and 1.0 mg P kg⁻¹ at 0-10 and 10-20 cm depth, respectively) in organic farming compared to conventional farming and forest at both depths. However, conventional farming and forest soils had similar microbial biomass (C, N, and P) content. After conversion of forest, the P stock significantly increased by 373% and 170% in soil under organic farming at 0-10 and 10-20 cm depth, respectively. In conventional farming, the P stock increased by 64% and 36% at 0-10 cm and 10-20 cm depth, respectively, compared to forest. Overall, organic farming practices, i.e., crop rotation, residue input and farmyard manure application, significantly alters soil fertility and microbial activity. Organic farming system is emerging as a sustainable land use system which can address the issues of food security and environment conservation by increasing sustainable agriculture production and carbon sequestration, respectively, supporting to achieve goals of sustainable development.

Keywords: organic farming, soil fertility, micobial biomas, food security

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Authors: Mehri Bagherkazemi, Naser Hafezi Moghaddas

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This study investigates the environmental impact of the disposal site located in Shahrood city, focusing on the geological characteristics of the region. Shahrood's disposal site primarily consists of limestone bedrock, overlaid by substantial alluvial deposits. The area's highly permeable soil is anticipated to have a significant influence on groundwater pollution. Spanning 52 hectares, the Shahrood disposal site is situated in the eastern sector of the city. Historically, waste disposal took place on the surface, but recent practices involve on-site trenching. This research involved the collection of soil and water samples near the disposal site, with subsequent analysis of 11 soil samples and 3 water samples. The soil's particle size distribution was determined, and comprehensive analyses were conducted for 35 elements in the soil and 42 elements in water. The study combines the results of these tests with field investigations to evaluate the landfill's impact on the surrounding soil and groundwater contamination.

Keywords: environmental geology, environmental impact assessment, disposal site, heavy metals contamination

Procedia PDF Downloads 55

Authors: C. S. Subhashini, H. L. Premaratne

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Landslides are the most recurrent and prominent disaster in Sri Lanka. Sri Lanka has been subjected to a number of extreme landslide disasters that resulted in a significant loss of life, material damage, and distress. It is required to explore a solution towards preparedness and mitigation to reduce recurrent losses associated with landslides. Artificial Neural Networks (ANNs) and Hidden Markov Model (HMMs) are now widely used in many computer applications spanning multiple domains. This research examines the effectiveness of using Artificial Neural Networks and Hidden Markov Model in landslides predictions and the possibility of applying the modern technology to predict landslides in a prominent geographical area in Sri Lanka. A thorough survey was conducted with the participation of resource persons from several national universities in Sri Lanka to identify and rank the influencing factors for landslides. A landslide database was created using existing topographic; soil, drainage, land cover maps and historical data. The landslide related factors which include external factors (Rainfall and Number of Previous Occurrences) and internal factors (Soil Material, Geology, Land Use, Curvature, Soil Texture, Slope, Aspect, Soil Drainage, and Soil Effective Thickness) are extracted from the landslide database. These factors are used to recognize the possibility to occur landslides by using an ANN and HMM. The model acquires the relationship between the factors of landslide and its hazard index during the training session. These models with landslide related factors as the inputs will be trained to predict three classes namely, ‘landslide occurs’, ‘landslide does not occur’ and ‘landslide likely to occur’. Once trained, the models will be able to predict the most likely class for the prevailing data. Finally compared two models with regards to prediction accuracy, False Acceptance Rates and False Rejection rates and This research indicates that the Artificial Neural Network could be used as a strong decision support system to predict landslides efficiently and effectively than Hidden Markov Model.

Keywords: landslides, influencing factors, neural network model, hidden markov model

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Authors: Maria Angela Bedini, Fabio Bronzini

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The risk of natural disasters affects all the countries of the world, whether it refers to seismic events or tsunamis or hydrogeological disasters. In most cases, the risk can be considered in its three components: hazard, exposure, vulnerability (and urban vulnerability). The aim of this paper is to evaluate how the Italian scientific community has related the contribution of these three components, superimposing the three different maps that summarize the fundamental structure of the risk. Based on the three components considered, the study applies the Regional Planning methodology on the three phases of the risk protection and mitigation process: the prevention phase, the emergency intervention phase, the post-disaster phase. The paper illustrates the Italian experience of the pre-during-post-earthquake intervention. Main results: The study deepens these aspects in the belief that “a historical center” and an “island” can present similar problems at the international level, both in the phase of prevention (earthquake, tsunamis, hydrogeological disasters), in emergency phase (protocols and procedures of intervention) and in the post-disaster phase. The conclusions of the research identify the need to plan in advance how to deal with the post-disaster phase and consider it a priority with respect to the simple reconstruction of destroyed buildings. In fact the main result of the post-disaster intervention must be the return and the social and economic support of the indigenous population, and not only the construction of new housing and equipment. In this sense, the results of the research show that the elderly inhabitants of a historic center can be compared to the indigenous population of an atoll of fishermen, as both constitute the most important resource: the human resource. Their return in conditions of security testifies, with their presence, the culture, customs, and values rooted in the history of a people.

Keywords: post-disaster interventions, risk of natural disasters in Italy and abroad, seismic events in Italy, social and economic protection and support for the native population of historical centers

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Authors: Benhammadi Hocine, Chaffai Hicham

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Urban development is often dependent on adequate land for expansion, except that sometimes these areas have vulnerability. This is the case of karst regions characterized by carbonate geological formations marked by the presence of cavities and cracks. The impact of climate variability in Cheria area marked by a growing shortage of rainfall, the impact resulted in the development of the vulnerability of these structures. This vulnerability has led to the appearance of collapse phenomena as well in both agricultural and urban areas. Two phenomena have emerged to explain the collapses, the first is assigned a filling process in the cavities, and the second is due to a weakening of the resistance that collapses limestone slab shear phenomenon. In urban areas, the weight of the buildings has increased the load on the limestone slab and accelerated the collapse. The analysis of the environmental process is in the context of our modest work, after which we indicate the appropriate methods for management policy of urban expansion. This management more preventive (upstream), much less expensive than remedial solutions (downstream) needed after the event and sometimes ineffective.

Keywords: Cheria, urban, climate variability, vulnerability karst collapse, extension, management

Procedia PDF Downloads 447

Authors: Md Y. Reja, Samuel D. Brody, Wesley E. Highfield, Galen D. Newman

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Historically, wetlands in the United States have been lost due to agriculture, anthropogenic activities, and rapid urbanization along the coast. Such losses of wetlands have resulted in high flooding risk for coastal communities over the period of time. In addition, alteration of wetlands via the Section 404 Clean Water Act permits can increase the flooding risk to future hurricane events, as the cumulative impact of this program is poorly understood and under-accounted. Further, recovery after hurricane events is acting as an encouragement for new development and reconstruction activities by converting wetlands under the wetland alteration permitting program. This study investigates the degree to which hurricane recovery activities in coastal communities are undermining the ability of these places to absorb the impacts of future storm events. Specifically, this work explores how and to what extent wetlands are being affected by the federal permitting program post-Hurricane Ike in 2008. Wetland alteration patterns are examined across three counties (Harris, Galveston, and Chambers County) along the Texas Gulf Coast over a 10-year time period, from 2004-2013 (five years before and after Hurricane Ike) by conducting descriptive spatial analyses. Results indicate that after Hurricane Ike, the number of permits substantially increased in Harris and Chambers County. The vast majority of individual and nationwide type permits were issued within the 100-year floodplain, storm surge zones, and areas damaged by Ike flooding, suggesting that recovery after the hurricane is compromising the ecological resiliency on which coastal communities depend. The authors expect that the findings of this study can increase awareness to policy makers and hazard mitigation planners regarding how to manage wetlands during a long-term recovery process to maintain their natural functions for future flood mitigation.

Keywords: ecological resiliency, Hurricane Ike, recovery, Section 404 Permitting, wetland alteration

Procedia PDF Downloads 234

Authors: Diego Diaz H., Cristian Larroulet

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Although a large earthquake has clear and immediate consequences such as deaths, destruction of infrastructure and displacement (at least temporary) of part of the population, scientific research about the impact of a geological disaster in economic activity is inconclusive, especially when looking beyond the very short term. Estimating the economic impact years after a disaster strike is non-trivial since there is an unavoidable difficulty in attributing the observed effect to the disaster and not to other economic shocks. Case studies are performed that determine the impact of earthquakes in Chile, Japan, and New Zealand at a regional level by applying the synthetic control method, using the natural disaster as treatment. This consisted in constructing a counterfactual from every region in the same country that is not affected (or is slightly affected) by the earthquake. The results show that the economies of Canterbury and Tohoku achieved greater levels of GDP per capita in the years after the disaster than they would have in the absence of the disaster. For the case of Chile, however, the region of Maule experiences a decline in GDP per capita because of the earthquake. All the results are robust according to the placebo tests. Also, the results suggest that national institutional quality improve the growth process after the disaster.

Keywords: earthquake, economic growth, institutional quality, synthetic control

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Authors: R. Lhissou , A. El Harti , K. Chokmani, E. Bachaoui, A. El Ghmari

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Soil salinity is a serious environmental hazard in many countries around the world especially the arid and semi-arid countries like Morocco. Salinization causes negative effects on the ground; it affects agricultural production, infrastructure, water resources and biodiversity. Remote sensing can provide soil salinity information for large areas, and in a relatively short time. In addition, remote sensing is not limited by extremes in terrain or hazardous condition. Contrariwise, experimental methods for monitoring soil salinity by direct measurements in situ are very demanding of time and resources, and also very limited in spatial coverage. In the irrigated perimeter of Tadla plain in central Morocco, the increased use of saline groundwater and surface water, coupled with agricultural intensification leads to the deterioration of soil quality especially by salinization. In this study, we assessed several spectral indices of soil salinity cited in the literature using Landsat TM satellite images and field measurements of electrical conductivity (EC). Three Landsat TM satellite images were taken during 3 months in the dry season (September, October and November 2011). Based on field measurement data of EC collected in three field campaigns over the three dates simultaneously with acquisition dates of Landsat TM satellite images, a two assessment techniques are used to validate a soil salinity spectral indices. Firstly, the spectral indices are validated locally by pixel. The second validation technique is made using a window of size 3x3 pixels. The results of the study indicated that the second technique provides getting a more accurate validation and the assessment has shown its limits when it comes to assess across the pixel. In addition, the EC values measured from field have a good correlation with some spectral indices derived from Landsat TM data and the best results show an r² of 0.88, 0.79 and 0.65 for Salinity Index (SI) in the three dates respectively. The results have shown the usefulness of spectral indices as an auxiliary variable in the spatial estimation and mapping salinity in irrigated land.

Keywords: remote sensing, spectral indices, soil salinity, irrigated land

Procedia PDF Downloads 375

Authors: Jeongwoo Lee

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Children are the most vulnerable travelers and they are at risk for pedestrian injury. Creating a safe route to school is important because walking to school is one of the main opportunities for promotion of needed physical exercise among children. This study examined how the built environmental attributes near an elementary school influence traffic accidents among school-aged children. The study used two complementary data sources including the locations of police-reported pedestrian crashes and the built environmental characteristics of school areas. The environmental attributes of road segments were collected through GIS measurements of local data and actual site audits using the inventory developed for measuring pedestrian-crash risk scores. The inventory data collected at 840 road segments near 32 elementary schools in the city of Ulsan. We observed all segments in a 300-meter-radius area from the entrance of an elementary school. Segments are street block faces. The inventory included 50 items, organized into four domains: accessibility (17items), pleasurability (11items), perceived safety from traffic (9items), and traffic and land-use measures (13items). Elementary schools were categorized into two groups based on the distribution of the pedestrian-crash hazard index scores. A high pedestrian-crash zone was defined as an school area within the eighth, ninth, and tenth deciles, while no pedestrian-crash zone was defined as a school zone with no pedestrian-crash accident among school-aged children between 2013 and 2016. No- and high pedestrian-crash zones were compared to determine whether different settings of the built environment near the school lead to a different rate of pedestrian-crash incidents. The results showed that a crash risk can be influenced by several environmental factors such as a shape of school-route, number of intersections, visibility and land-use in a street, and a type of sidewalk. The findings inform policy for creating safe routes to school to reduce the pedestrian-crash risk among children by focusing on school zones.

Keywords: active school travel, school zone, pedestrian crash, safety route to school

Procedia PDF Downloads 231

Authors: Emad Amar, Tawfik Khattab, Fatma Zada

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Predicting earthquakes is an important issue in the study of geography. Accurate prediction of earthquakes can help people to take effective measures to minimize the loss of personal and economic damage, such as large casualties, destruction of buildings and broken of traffic, occurred within a few seconds. United States Geological Survey (USGS) science organization provides reliable scientific information of Earthquake Existed throughout history & Preliminary database from the National Center Earthquake Information (NEIC) show some useful factors to predict an earthquake in a seismic area like Aleutian Arc in the U.S. state of Alaska. The main advantage of this prediction method that it does not require any assumption, it makes prediction according to the future evolution of object's time series. The article compares between simulation data result from trained BP and RBF neural network versus actual output result from the system calculations. Therefore, this article focuses on analysis of data relating to real earthquakes. Evaluation results show better accuracy and higher speed by using radial basis functions (RBF) neural network.

Keywords: BP neural network, prediction, RBF neural network, earthquake

Procedia PDF Downloads 476

Authors: Md. Refat Jahan Rakiba, M. Belal Hossaina, Rakesh Kumarc, Md. Akram Ullaha, Sultan Al Nahiand, Nazmun Naher Rimaa, Tasrina Rabia Choudhury, Samia Islam Libaf, Jimmy Yub, Mayeen Uddin Khandakerg, Abdelmoneim Suliemanh, Mohamed Mahmoud Sayedi

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Microplastics (MPs) have become an emerging global pollutant due to their wide spread and dispersion and potential threats to marine ecosystems. However, studies on MPs of estuarine and coastal ecosystems of Bangladesh are very limited or not available. In this study, we conducted the first study on the abundance, distribution, characteristics and potential risk assessment of microplastics in the sediment of Karnaphuli River estuary, Bangladesh. Microplastic particles were extracted from sediments of 30 stations along the estuary by density separation, and then enumerated and characterize by using steromicroscope and Fourier Transform Infrared (FT-IR) spectroscopy. In the collected sediment, the number of MPs varied from 22.29 - 59.5 items kg−1 of dry weight (DW) with an average of 1177 particles kg−1 DW. The mean abundance was higher in the downstream and left bank of estuary where the predominant shape, colour, and size of MPs were films (35%), white (19%), and >5000 μm (19%), respectively. The main polymer types were polyethylene terephthalate, polystyrene, polyethylene, cellulose, and nylon. MPs were found to pose risks (low to high) in the sediment of the estuary, with the highest risk occuring at one station near a sewage outlet, according to the results of risk analyses using the pollution risk index (PRI), polymer risk index (H), contamination factors (CFs), and pollution load index (PLI). The single value index, PLI clearly demonastated that all sampling sites were considerably polluted (as PLI >1) with microplastics. H values showed toxic polymers even in lower proportions possess higher polymeric hazard scores and vice versa. This investigation uncovered new insights on the status of MPs in the sediments of Karnaphuli River estuary, laying the groundwork for future research and control of microplastic pollution and management.

Keywords: microplastics, polymers, pollution risk assessment, Karnaphuli esttuary

Procedia PDF Downloads 57

Authors: S. Cowley, M. Lawrance, D. Bick, R. McCord

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Technology that automates manual handling (musculoskeletal disorder or MSD) risk assessments is increasingly available to ergonomists, engineers, generalist health and safety practitioners alike. The risk assessment process is generally based on the use of wearable motion sensors that capture information about worker movements for real-time or for posthoc analysis. Traditionally, MSD risk assessment is undertaken with the assistance of a checklist such as that from the SafeWork Australia code of practice, the expert assessor observing the task and ideally engaging with the worker in a discussion about the detail. Automation enables the non-expert to complete assessments and does not always require the assessor to be there. This clearly has cost and time benefits for the practitioner but is it an improvement on the assessment by the human. Human risk assessments draw on the knowledge and expertise of the assessor but, like all risk assessments, are highly subjective. The complexity of the checklists and models used in the process can be off-putting and sometimes will lead to the assessment becoming the focus and the end rather than a means to an end; the focus on risk control is lost. Automated risk assessment handles the complexity of the assessment for the assessor and delivers a simple risk score that enables decision-making regarding risk control. Being machine-based, they are objective and will deliver the same each time they assess an identical task. However, the WHS professional needs to know that this emergent technology asks the right questions and delivers the right answers. Whether it improves the risk assessment process and results or simply distances the professional from the task and the worker. They need clarity as to whether automation of manual task risk analysis and reporting leads to risk control or to a focus on the worker. Critically, they need evidence as to whether automation in this area of hazard management leads to better risk control or just a bigger collection of assessments. Practitioner experienced determinants of this automated manual task risk analysis and reporting being a benefit or distraction will address an understanding of emergent risk assessment technology, its use and things to consider when making decisions about adopting and applying these technologies.

Keywords: automated, manual-handling, risk-assessment, machine-based

Procedia PDF Downloads 101

Authors: Stefano Barone

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Seismic retrofit of buildings through base isolation represents a consolidated protection strategy against earthquakes. It consists in decoupling the ground motion from that of the structure and introducing anti-seismic devices at the base of the building, characterized by high horizontal flexibility and medium/high dissipative capacity. This allows to protect structural elements and to limit damages to non-structural ones. For these reasons, full functionality is guaranteed after an earthquake event. Base isolation is applied extensively to both new and existing buildings. For the latter, it usually does not require any interruption of the structure use and occupants evacuation, a special advantage for strategic buildings such as schools, hospitals, and military buildings. This paper describes the application of seismic isolation to three existing masonry buildings in Italy: Villa “La Maddalena” in Macerata (Marche region), “Giacomo Matteotti” and “Plinio Il Giovane” school buildings in Perugia (Umbria region). The seismic hazard of the sites is characterized by a Peak Ground Acceleration (PGA) of 0.213g-0.287g for the Life Safety Limit State and between 0.271g-0.359g for the Collapse Limit State. All the buildings are isolated with a combination of free sliders type TETRON® CD with confined elastomeric disk and anti-seismic rubber isolators type ISOSISM® HDRB to reduce the eccentricity between the center of mass and stiffness, thus limiting torsional effects during a seismic event. The isolation systems are designed to lengthen the original period of vibration (i.e., without isolators) by at least three times and to guarantee medium/high levels of energy dissipation capacity (equivalent viscous damping between 12.5% and 16%). This allows the structures to resist 100% of the seismic design action. This article shows the performances of the supplied anti-seismic devices with particular attention to the experimental dynamic response. Finally, a special focus is given to the main site activities required to isolate a masonry building.

Keywords: retrofit, masonry buildings, seismic isolation, energy dissipation, anti-seismic devices

Procedia PDF Downloads 52