Fuzzy Possibilistic Modeling for Closed Loop Recycling Collection Networks

Nowadays, in the competitive market, commercial companies due to their economic problems and also restrictions imposed by international organizations to comply with environmental regulations are making noticeable efforts to reduce the level of their wastes in their manufacturing systems and consequently the level of waste in consumers’ products. In harmony with this issue, one of the most effective ways which has successfully been used and proven to be economically profitable is to take products lifecycles into consideration. Consideration of products lifecycle has made supply chain practitioners to investigate the reverse logistics activities in addition to forward logistics activities. Hence, corporations, in order to reduce their cost on the one hand and boosting their efficiency on the other hand, were obligated to employ closed loop supply chain models to concurrently benefit from its economical and environmental advantages. Therefore, in this paper, a mixed nonlinear facility location–allocation model is proposed for recycling collection centers. The considered closed loop logistics model consists of multiple echelons, multiple suppliers, multiple collection centers, multiple time period and also multiple facilities. In real-life problems parameters like demand, cost, capacity, distances, and quantities of returned products are always uncertain. Therefore, in order to solve a realistic problem, foregoing parameters are considered as fuzzy in our proposed model. Subsequently, to solve fuzzy mixed nonlinear programming model, one of the most effective technique in the literature is used. Additionally, in order to demonstrate the behavior of the parameters employed in the model, a comprehensive sensitivity analysis is conducted. Computational results demonstrate that the proposed model can show favorable efficiency in solving supply chain problems.     

Risk assessment for hazardous lubricants in machining industry

Knowing that over two-thirds of lubricant disposals return to the environment with no purification process, adequate strategies are demanded to reduce their risks. For this reason, the main focus of the present study is to describe an environment-friendly approach. In the first part, two widely used lubricants (mineral-based and vegetable-based) were introduced, and the reasons for their hazards were investigated. The composition of mineral-based lubricant was characterized by x-ray fluorescence elemental analysis. The result showed the presence of phosphorus, chlorine, and zinc dialkyl dithiophosphate in its composition that many scholars considered them to be the leading risk factor in the chemical composition of mineral-based lubricants. It has been focused on the potential risks of vegetable-based lubricants, which many researchers have identified as a safe lubricant. The Pseudomonas microbe was cultivated in the vegetable-based sample, and the result showed that although vegetable-based lubricants are compatible with humans, bacteria colony can quickly grow there without making any apparent changes that lead to harm to operators in a mysterious way. In the present work, the hypothesis of the safety of unreinforced vegetable-based lubricants has been rejected, and a new window on the environmental issues of vegetable-based lubricants has been presented. In the final, to eliminate environment-human risks and to reduce consumption of lubricant and natural resources to green manufacturing, a comprehensive study on the possibility of completely removing lubricant was performed. The results showed that the machining without lubricant could be replaced with the traditional method.

     

Three-dimensional analysis of coherent turbulent flow structure around a single circular bridge pier

The coherent turbulent flow around a single circular bridge pier and its effects on the bed scouring pattern is investigated in this study. The coherent turbulent flow and associated shear stresses play a major role in sediment entrainment from the bed particularly around a bridge pier where complex vortex structures exist. The conventional two-dimensional quadrant analysis of the bursting process is unable to define sediment entrainment, particularly where fully three-dimensional flow structures exist. In this paper, three-dimensional octant analysis was used to improve understanding of the role of bursting events in the process of particle entrainment. In this study, the three-dimensional velocity of flow was measured at 102 points near the bed of an open channel using an Acoustic Doppler Velocity meter (Micro-ADV). The pattern of bed scouring was measured during the experiment. The velocity data were analysed using the Markov process to investigate the sequential occurrence of bursting events and to determine the transition probability of the bursting events. The results showed that external sweep and internal ejection events were an effective mechanism for sediment entrainment around a single circular bridge pier. The results are useful in understanding scour patterns around bridge piers.     

Distribution,source apportionment and health risk assessment of polycyclic aromatic hydrocarbons (PAHs) in intertidal sediment of Asaluyeh,Persian Gulf

Surface sediment samples were collected from intertidal zone of Asaluyeh, Persian Gulf, to investigate distribution, sources and health risk of sixteen polycyclic aromatic hydrocarbons (PAHs). Total PAH concentrations ranged from 1.8 to 81.2 μg kg^?1 dry weight, which can be categorized as low level of pollution. Qualitative and quantitative assessments showed that PAHs originated from both petrogenic and pyrogenic sources with slight pyrogenic dominance. Source apportionment using principal component analysis indicated that the main sources of PAHs were fossil fuel combustion (33.59%), traffic-related PAHs (32.77%), biomass and coal combustion (18.54%) and petrogenic PAHs (9.31%). According to the results from the sediment quality guidelines, mean effects range-median quotient (M-ERM-Q) and benzo[a]pyrene toxic equivalents (BaP_eq), low negative ecological risks related to PAH compounds would occur in the intertidal zone of Asaluyeh. The total benzo[a]pyrene (BaP) toxic equivalent quotient (TEQ^carc) for carcinogenic compounds ranged from 0.01 to 7 μg kg^?1-BaP_eq, indicating low carcinogenic risk. The human health risk assessment of PAH compounds via ingestion and dermal pathways suggests low and moderate potential risk to human health, respectively.     

Distribution,sources and pollution status of Pb in indoor and outdoor dusts of Kerman City,SE Iran

The aims of this study were to explore the status of pollution and the temporal/spatial distribution of indoor and outdoor dust-Pb in the city of Kerman (SE Iran), located in a dry playa and arid climatic zone. Flat panes were laid at appropriate locations, in the indoor and the outdoor spaces of selected one-story houses in different areas of the city, to collect dust samples. Forty-two samples were taken and analyzed using the ICP-MS method. The measurements have shown that the outdoor dust-Pb concentrations varied from 23.7 to 275.2?mg kg^?1, with a mean value of 71.8?mg kg^?1, and indoor dust-Pb concentrations ranged from 47.6 to 150.2?mg kg^?1, with a mean value of 89.6?mg kg^?1. Based on these measurements, Pb was enriched in the outdoor and the indoor dust samples up to 48.8 and 29.4 times, respectively. Dilution, as a result of prevalence of geogenic dust in the outdoor space, is expected to be the main cause of the temporal differences. This study has shown that the eastern part of the city is more polluted compared to the other parts, and, because of the stable air conditions, the concentration of Pb in the summer dust is higher than the other seasons.     

Environmental protection stability of river bed and banks using convex, concave, and linear bed sills

River bed scourings are a major environmental problem for fish and aquatic habitat resources. In this study, to prevent river bed and banks from scouring, different types of bed sills including convex, concave and linear patterns were installed in a movable channel bed in a laboratory flume. The bed sills were tested with nine different arrangements and under different flow conditions. To find the most effective bed sill pattern, the scouring depth was measured downstream of the bed sill for a long experimental duration. The scour depth was measured at the middle and at the end of each experimental test for different ratios of the arch radius to the channel width $(r/\emph{w})$ . The experimental results indicated that the convex pattern with $r/\emph{w}=0.35$ produced minimum bed scouring depth at the center line whereas the concave pattern with $r/\emph{w}=0.23$ produced the minimum scour depth at the wall banks. Therefore, the convex pattern was the most effective configuration for prevention of scouring at the center line of the river while the concave pattern was very effective to prevent scouring at the river banks. These findings can be suggested to be used in practical applications.     

Quality of drinking water and high incidence rate of esophageal cancer in Golestan province of Iran: a probable link

Golestan province in north Iran is known to be a high-risk area for esophageal cancer (EC). Of a long list of multiple risk factors, this study focuses on a possible link between the epidemiologic patterns of EC and the anomalous concentration of some ions and elements in the drinking water sources. A total of 183 samples from 45 villages covering a wide range of EC mortality rates are collected and analyzed. The results demonstrate that NO₃ ⁻, SO₄ ²⁻, Sb, and Sr exceed the recommended maximum concentration level (MCL) in drinking water. This is more prominent in the villages with high esophageal cancer mortality rate, suggesting a possible link between EC incidence and water quality. Se concentration in drinking water increases from low to the high EC areas, a finding contrary to the expected trend. It is concluded that Se deficiency does not play a major role in the etiology of EC in the Golestan province. The statistical results obtained from Mann–Whitney and Kruskal–Wallis tests along with cluster analysis are consistent with the observed trend of EC mortality rate in Golestan province.     

Oxidative potential (OP) and mineralogy of iron ore particulate matter at the Gol-E-Gohar Mining and Industrial Facility (Iran)

Concentrations of total suspended particulate matter, particulate matter with aerodynamic diameter <2.5 μm (PM_2.5), particulate matter <10 μm (PM₁₀), and fallout dust were measured at the Iranian Gol-E-Gohar Mining and Industrial Facility. Samples were characterized in terms of mineralogy, morphology, and oxidative potential. Results show that indoor samples exceeded the 24-h PM_2.5 and PM₁₀ mass concentration limits (35 and 150 µg m^?3, respectively) set by the US National Ambient Air Quality Standards. Calcite, magnetite, tremolite, pyrite, talc, and clay minerals such as kaolinite, vermiculite, and illite are the major phases of the iron ore PM. Accessory minerals are quartz, dolomite, hematite, actinolite, biotite, albite, nimite, laumontite, diopside, and muscovite. The scanning electron microscope structure of fibrous-elongated minerals revealed individual fibers in the range of 1.5 nm to 71.65 µm in length and 0.2 nm to 3.7 µm in diameter. The presence of minerals related to respiratory diseases, such as talc, crystalline silica, and needle-shaped minerals like amphibole asbestos (tremolite and actinolite), strongly suggests the need for detailed health-based studies in the region. The particulate samples show low to medium oxidative potential per unit of mass, in relation to an urban road side control, being more reactive with ascorbate than with glutathione or urate. However, the PM oxidative potential per volume of air is exceptionally high, confirming that the workers are exposed to a considerable oxidative environment. PM released by iron ore mining and processing activities should be considered a potential health risk to the mine workers and nearby employees, and strategies to combat the issue are suggested.     

Facilitators and barriers to occupational health and safety in small and medium-sized enterprises: a descriptive exploratory study in Ontario,Canada

Purpose. The purpose of this particular study was to test a newly created instrument in describing the facilitators and barriers to occupational health and safety in small and medium-sized enterprises (SMEs) in Ontario, Canada. Methods. A cross-sectional design was used to identify the occupational health and safety culture of SMEs in public and private sectors in Ontario. Results. A total of 153 questionnaires were completed. The majority of respondents were female (84%) with a mean age of 49.8 years (SD 10.6). Seventy-four percent were supervisors. Seventy percent of respondents were from the private sector while 30% derived from the public sector including healthcare, community services, and non-profit organizations. Further, conducting regular external safety inspections of the workplace was found to be statistically associated with a safe work environment 2.88 95% CI [1.57, 5.27]. Conclusions. Strategies and training opportunities that focus on how to adapt occupational health and safety legislation to the nature and diversity of SMEs are recommended. Furthermore, employers may use such information to improve safety in their SMEs, while researchers can hopefully use such evidence to develop interventions that are applicable to meeting the occupational health and safety needs of SMEs.