خيارات البحث
النتائج 471 - 480 من 62,508
Palm kernel fruit fiber reinforced gypsum-cement based wall panels: It’s physical and mechanical characteristics النص الكامل
2015
Abuh, Noah | Umoh, Akaninyene
Agricultural waste fibers have been found to be suitable as reinforcement in cement-based composites, but studies on oil palm fiber as reinforcement in gypsum-cement wall panels are scarce. A mixture of two equal weights of gypsum and cement, with water-binder ratios of 0.45 and 0.55 were prepared. In each mix a varying percentage of fiber contents of 2%, 3% and 4% by weight of the binders were added. The properties of the wall panels were determined from cast specimen sizes of 100x 100 x 40 mm for density, moisture content and water absorption; 160 x 40 x 40mm for compressive strength, and 650 x 100 x 25 mm for bending strength. The specimens were cured in water and tested at ages of 3, 7, 14, 21, and 28 days. The results of density of the wall panels were within the range of 1634–1742 kg/m3, while the moisture content range of 3.30–8.45%, and the water absorption varies from 5 to 12%. The compressive strengths were found within the range of 1.92–5.20N/mm2 and, generally, decreases with the increasing percentage of fiber contents, but increased with curing age. The bending strength falls within the range of 2.04–4.13 N/mm2that increases with curing age and slightly increased with fiber content. It is concluded that oil palm fiber reinforced gypsum-cement wall panels are suitable as wall element.
اظهر المزيد [+] اقل [-]Evaluating the consequences of the new standards on noise conditions in ships النص الكامل
2015
Bouzón, Rebeca | Costa, Angel M | Roshan, Gholamreza | Orosa, J.A.
Noise is one of the main parameters to be considered to achieve a healthy indoor ambience in ferries. Therefore, the noise standards need to be more specialized and specifically based on real sampled data and case studies. In the present research, the noise levels in a ship, under different working conditions, were sampled and compared with those specified in the new and old standards. An initial study showed two main noise sources- clients and main engine- that influence other indoor environments, reducing the quality of life on board. The real-time data revealed that the maximum noise level limits set by the International Maritime Organization (IMO) in the older Resolution A.468 (XII) was mostly respected, except in areas where maintenance of the noise level was difficult, owing to the continuous influx of people, especially at the time of boarding and disembarking of the passengers and at the food self-service areas. In this sense, under the new Resolution MSC.337 (91), the maximum noise level allowed in the accommodation has been reduced by 5 dB (A), but this environment does not meet the standard. More results show that future standards must not only consider the noise level in a working place and add another variable, such as, the number of working hours, to obtain a representative equivalent energy, and they must also consider that a simple modification of this standard implies a redesign of most of the indoor ambiences onboard.
اظهر المزيد [+] اقل [-]Impact of copper mines and smelter on groundwater quality (Case Study: Rajasthan State in India) النص الكامل
2015
Hussain, Ikbal | Hussain, Jakir | Arif, Mohammed | Vadiya, Vinod
Rajasthan is one of the main mineral potential state of India. During the last 30 years it has witnessed enormous expansion of mining industries, but mining of most of the minor minerals coupled with changing climate has posed serious problems to the environmental fabric in the state, apart from base metal beneficiation plants. Groundwater is also being polluted day-by-day by effluents generated from mineral wastes and beneficiation processes in the vicinity of mining sites such as Khetri. Pollutant concentrations were measured in groundwater at the vicinity of Khetri copper mining project, Rajasthan to investigate the influence of copper mining on environment. Pollutant concentrations in groundwater were investigated. Copper metal concentration in water samples were found above the maximum desirable limit in two sources: G4 and G5, due to washing away of mineral with water. Mining industry has deteriorated quality of groundwater resources in the state of Rajasthan, and these industries are becoming centers of pollution sources which need timely actions at government level so that natural resources such as groundwater can be protected.
اظهر المزيد [+] اقل [-]Collection and recycle bin location-allocation problem in solid waste management: A review النص الكامل
2015
Purkayastha, Debasree | Majumder, Mrinmoy | Chakrabarti, Sumanta
This comprehensive work explores the research performed inoptimization of the collection bin and in recycle bin location-allocation issues in solidwaste management. Although the collection phase of solid waste management accountsfor a significant proportion of the municipal budget, it has attracted only limitedattention of the researchers. Optimization of the collection bin and recycle bin location-allocation problems in solid waste management can be advantageous with respect to binaccess to every individual person of municipality, reduction in the numbers of opendumping yards, considerable profit if the recycled products are properly processed, andas an effort toward sustainable and green world. Hence, the topic of interest should bepursued, especially in developing countries, to enable development of a cost-efficient and sustainable solid waste management system.
اظهر المزيد [+] اقل [-]Laser land levelling as a strategy for environmental management: the case of Iran النص الكامل
2015
Tohidyan Far, Somayeh | Rezaei-Moghaddam, Kurosh
The impact assessment method seeks to bring about a more ecologically, socio-culturally and economically sustainable and equitable environment. Determining the main factors affecting the attitudes of stakeholders is crucial for understanding the impacts of development plans. This approach helps planners and decision makers to identify the values and traits of stakeholders and accelerate the diffusion of innovations through designing proper incentives and removing available obstacles. The purpose of this study is to examine factors affecting laser land levelling project impacts in Fars Province, Iran. The sample included 285 farmers who were selected using multi-stage random sampling. The validity and reliability of the questionnaire were measured and revisions were made to improve measurement scales. The results of structural equation modelling indicated that reduction in water consumption was the most important variable which affected the recognition of impacts among laser land levelling adopters. Furthermore, laser land levelling impacts as dependent variables were influenced by the direct effect of the duration of adoption, attitude towards water and soil conservation, need perception and attitude toward prior projects. Based on the results, practical recommendations have been presented.
اظهر المزيد [+] اقل [-]Comparison of the environmental indicators of phosphorus efficiency and the balance between saffron and wheat production systems in the Qaenat region, Iran النص الكامل
2015
Yaeghoubi, Fatemeh | Jami Al-Ahmadi, Majid | Bakhshi, Mohammad Reza | Sayyari-Zahan, Mohammad Hassan
Improving the resource use efficiency in agro- ecosystems is an importantfactor for reducing environmental pollution. To evaluate phosphorus (P) efficiency andbalance indicators, research was conducted in wheat and saffron production systems inthe Qaenat region (South Khorasan Province, Iran) during 2011 and 2012, based on themethod of the Organization for Economic Co-operation and Development (OECD). Therequired information about wheat and saffron cultivation was collected via questionnairesand the required coefficients were obtained from various literatures. The results showedthat the phosphorus efficiency and balance indicators were significantly different betweendistinct districts only in the case of wheat crops. The highest P efficiencies of wheat andsaffron farms were 7.21% and 2.93%, respectively. Additionally, P efficiency andbalance indicators showed a significant difference between both crops in some districts,so that wheat had higher P efficiency than saffron, which was mainly because of thedifferent amounts of animal manure applied to these crops. There was no significantdifference between the different ages of saffron farms for P efficiency and balance.Furthermore, there was a significant negative correlation between P efficiency andbalance indicators. It would appear that there are many opportunities for improving theefficiency of P and to prevent environmental pollution through the optimization ofmanagement decisions.
اظهر المزيد [+] اقل [-]Spatial–Temporal Monitoring of Ecotonal Belt Using Landscape Ecological Indices in the Central Elburz Region: Remote Sensing and GIS Analysis النص الكامل
2015
Yavari, Ahmad Reza | Jafari, Hamid Reza | Hashemi, Seyyed Mahmood
Iran has mountainous landscapes and half of its surface is occupied by highlands. Moreover, Iran is an arid country and deserts are located at lower altitudes. Most metropolitan areas are positioned in mid-altitudes between mountain and desert. Cities grow upwardly toward the highlands under pressures of urbanization and desertification. Foothill ecotones are a zone between upland mountains and midland plains. Upwardly sprawl of urban centers has transformed the structures and functions of these ecologically strategic belts. In this article, we analyzed the transformational trend of the ecotonal zone in the southern slopes of the central Elburz (Tehran-Karaj urban region). Landsat 7 ETM+ (2000) and 8 OLI (2013) are used to monitor spatial and temporal variability of landscape metrics. The land covers are grouped into four classes: vegetation cover, open space, built area, and water body. Seven landscape metrics are used including: NP, CAP, MPS, AW-MPS, MNND, PARA, and TE. Our results indicate that NP, AW-MPS, TE, and PARA increased whereas CAP and MPS decreased. These results are a sign of the fragmentation process across the ecotonal strip.
اظهر المزيد [+] اقل [-]Hematological responses of Goldfish (Carassiusauratus) to different acute concentrations of Silver Sulfate as a toxicant النص الكامل
2015
Abarghoei, Safoura | Hedayati, Seyed Aliakbar | Ghafari Farsani, Hamed | Gerami, Mohammad Hasan
This study aimed to evaluate the efficacy of silver sulfate (AgSO4) as a toxicant in goldfish (Carassiusauratus). One hundred and forty-seven live specimens of C. auratus were obtained and exposed to 1, 10, 100, 500, 1000 and 2000 ppm of AgSO4for 96 hours. There was one control group (no AgSO4) and three replicates. The physicochemical properties of water and the following parameters were constant: pH: 7.56±0.45 (TS1); temperature: 19±1°C; hardness: 293±2.35 ppm and dissolved oxygen: 8.80 ±0.06 mg L-1 (DO-5510). LC1, LC10, LC30, LC50, LC70, LC90 and LC99 were calculated in 24, 48, 72 and 96 hours. For assessing the impact ofAgSO4 on physiological responses of goldfish hematological indices, blood glucose and cortisol levels were measured. Results showed that LC50 96-h of AgSO4 for goldfish was 687.81 ppm. In addition, the use of AgSO4induces a significant decrease in MCHE after 48 hours, MCV and MCH after 96 hours and lymphocyte after 96 hours in contrast to the control group (P<0.05). Furthermore, increased lymphocyte was significant after 24 hours exposure (P<0.05). In addition, glucose increased significantly at P<0.05 with time increase24 hours after experiment but this (). In conclusion, the study showed that acute toxicity of AgSO4induced hematological alterations in goldfish and offers a tool for the evaluation oftoxicity-derived alterations.
اظهر المزيد [+] اقل [-]Assessing environmental contamination of River Ganga using correlation and multivariate analysis النص الكامل
2015
Bhutiani, Rakesh | Khanna, D.R. | Tyagi, Bharti | Tyagi, Prashant | Kulkarni, Dipali
The aim of this study was to assess the environmental impact of socio-cultural practices on the water quality of River Ganga at the foothills of the Garhwal Himalayas in Uttarakhand State, India. The physico-chemical parameters that contributed to the temporal variation and pollution in the river were identified in this study. Principal component analysis (PCA) and Cluster analysis (CA) were used in the identification of anthropogenic factors (industrial, urban sewage, agricultural, land use and mining activities) and natural factors (soil erosion, weathering). The results of this study show that total coliform, fecal coliform, nitrate, sodium, phosphate, sulphate, TDS (Total dissolved solids), temperature, BOD (Biochemical oxygen demand), calcium and chloride are parameters significantly contributing to pollution load.
اظهر المزيد [+] اقل [-]Development of a new low-cost procedure for wind farm maintenance with a view to decrease soil pollution النص الكامل
2015
Costa, Angel M. | Fraguela, Feliciano | Orosa, Jos&eacute; A. | Roshan, Gholamreza
The purpose of this article is to present the development of a wind farm, with a condition monitoring system (CMS) based on control charts as the algorithm, centred on a new index, to prevent soil pollution by oil spills in wind farms. To this end, temperature sensors can be considered as one of the more significant sensors to be employed in this study, because the information obtained with regard to anemometers and electrical power output counters can be employed by the control system. As a result, among the other variables, oil temperatures sampled in multipliers used in the wind turbines of a real wind farm were employed. Statistical analyzes were developed and the relationship between wind farm maintenance (usually related to wind farm oil spills) and oil temperature was obtained. Furthermore, a practical case study, centered in the statistical process control, based on the low-cost sample variable was developed and showed that this new procedure would improve deficiencies in the maintenance process, thus, reducing the failure detection time under low sensor cost, as also the related soil pollution.
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