A review on comparative study of Savonius wind turbine rotor performance parameters

One approach for reducing the level of environmental contamination threats around the world is to use renewable energy-harvesting equipment. Wind is a potential environmental resource that has become a desirable aspect of urban use due to advances in wind turbine design technology. Other variants have been developed based on the classic vertical-axis Savonius rotor model, which, according to experimental test findings and computational calculations, show higher operational characteristics performance. Generated power and shaft torque operational results are obtained by providing specific rotor blade shapes in these models, one of the most common designs, among small-scale rotor which uses a drag-based vertical axis whereas Savonius turbines having large-scale rotors not developed yet. This kind of rotor has the advantages of being simple to design, affordable, performing well at low speeds, and turns to flow direction independently. However, it was discovered that the Savonius rotor suffers through high quantity of negative torques created by the returning blade after a number of examinations into its performance. Many studies on various rotor types have been conducted to resolve the Savonius turbine’s performance constraints. The research showed and analyzed the difficulties and modification in design parameters of rotor, as well as their major impact on rotor performance.

     

Air pollutant levels are 12 times higher than guidelines in Varanasi,India. Sources and transfer

Air quality in an urban atmosphere is regulated by both local and distant emission sources. For air quality management in urban areas, identification of sources and their relationships with local meteorology and air pollutants are essential. The critical condition of air quality in Indo-Gangetic plain is well known, but lack of data on both local and distant emission sources limits the scope of improving air quality in this region. Concentrations of particulate matter of size lower than 10 μm (PM₁₀) were assessed in the highly urbanized Varanasi city situated in middle Indo-Gangetic plain of India from 2014 to 2017, to identify the distant air pollution sources based on trajectory statistical models and local sources by conditional bivariate probability function. Modifying effects of meteorology and air pollutants on PM₁₀ were also explored. Mean PM₁₀ concentration for the study period was 244.8 ± 135.8 μg m^?3, which was 12 times higher than the WHO annual guideline. Several distinct sources of traffic as the major source of PM₁₀ were identified in the city. Trajectory statistical models like cluster analysis, potential source contribution function and concentration-weighted trajectory showed significant contributions from north-west and eastern directions in the transport of polluted air masses to the city. Dew point, wind speed, temperature and ventilation coefficient are the major factors in PM₁₀ formation and dispersion.     

Studies on the utility of plant cellulose waste for the bioadsorption of crystal violet dye

Several synthetic dyes employed in textile and food industries are discharged into aquatic environment. These visible pollutants in water damage environment, as they are carcinogenic and toxic to humans. The use of cost effective and ecofriendly plant cellulose based adsorbents have been studied in batch experiments as an alternative and effective substitution of activated carbon for the removal of toxic dyes from waste water. Adsorbents prepared from sugarcane baggase, were successfully used to remove certain textile dye such as crystal violet from an aqueous solution. The present investigation potentiate the use of sugarcane baggase, pretreated with formaldehyde (referred as Raw Baggase) and sulphuric acid (referred as Chemically Activated Baggase), for the removal of crystal violet dye from simulated waste water. Experiments were carried out at neutral pH with various parameters like dye concentration, temperature, contact time and adsorbent dosage. Efficiency of raw baggase was found better than chemically activated baggase for adsorption of crystal violet dye. The data obtained perfectly fits in the Freundlich adsorption isotherm.     

Hybridization between the blue mussels Mytilus galloprovincialis and M. trossulus along the Pacific coast of North America: evidence for limited introgression

Two species of blue mussel, Mytilus galloprovincialis and M. trossulus, co-occur and hybridize along the Pacific coast of North America. Using a set of polymerase chain-reaction (PCR)-based genetic markers which diagnostically identify these species, we show that they are sympatric from the Cape Mendocino region to the Monterey Peninsula in northern and central California, USA. Mussels with hybrid genotypes were detected in all populations sampled in the region of sympatry, and the frequency of hybrid genotypes in individual hybrid populations ranged from 13 to 44%. Significant frequencies of first-generation backcross genotypes were detected in two individual hybrid zone populations (Berkeley and Monterey Marina) and in the hybrid zone as a whole, indicating that the potential exists for introgression between M. galloprovincialis and M. trossulus. Despite this potential, we found no evidence of advanced introgression beyond first-generation backcrosses, suggesting that gene flow between M. galloprovincialis and M. trossulus has been quite limited. The frequency of mussels with M. trossulus and hybrid genotypes declined abruptly south of Monterey Peninsula, while the frequency of mussels with M. galloprovincialis and hybrid genotypes declined precipitously north of Cape Mendocino. These abrupt genetic discontinuities indicate that this blue mussel hybrid zone is presently positioned between two prominent coastal features and there is little, if any, export of alleles from the hybrid zone into bordering parental populations. Received: 20 August 1997 / Accepted: 26 October 1998     

Olivine dissolution from Indian dunite in saline water

The rate and mechanism of olivine dissolution was studied using naturally weathered dunite FO_98.21(Mg_1.884Fe_0.391SiO₄) from an Indian source, that also contains serpentine mineral lizardite. A series of batch dissolution experiments were carried out to check the influence of temperature (30–75 ^°C), initial dunite concentration (0.5 and 20 g/L), and salinity (0–35 g/L NaCl) under fixed head space CO₂ pressure (P\(_{\text {CO}_{2}}\) = 1 barg) on dunite dissolution. Dissolved Mg, Si, and Fe concentrations were determined by inductive coupled plasma atomic emission spectroscopy. End-product solids were characterized by scanning electron microscopy and X-ray diffraction. Initially, rates of dissolution of Si and Mg were observed to be in stoichiometric proportion. After 8 h, the dissolution rate was observed to decline. At the end of the experiment (504 h), an amorphous silica-rich layer was observed over the dunite surface. This results in decay of the dissolution rate. The operating conditions (i.e., salinity, temperature, and mineral loading) affect the dissolution kinetics in a very complex manner because of which the observed experimental trends do not exhibit a direct trend.     

Rheological and Mechanical Properties of Poly(lactic acid)/Bio-Based Polyethylene/Clay Biocomposites Containing Montmorillonite and Vermiculite Clays

Journal of Polymers and the Environment - This work aims to investigate the effect of organically modified montmorillonite (OMMT) and vermiculite (OVT) clays on the properties of poly(lactic acid)...     

World air particulate matter: sources,distribution and health effects

Particulate matter (PM) is both a major driver of climate change and a source of toxicity for health. In the upper atmosphere, particulate matter modifies the earth radiation budget, cloud formation and acts as a reaction center for air pollutants. In the lower atmosphere, particulate matter changes atmospheric visibility and alters biogeochemical cycles and meteorology. Most critical effects are observed in ambient air, where particulate matter degrades human health. Here we review the sources, spatial and temporal variability, and toxicity of PM₁₀, the particulate matter having particle sizes 10 micrometers or less in diameter, in world regions. For that we analyzed information from the world wide web and databases from government organizations after the year 2000. Findings show that PM₁₀ is a major risk in both developed and developing countries. This risk is more severe in Asian countries compared to Europe and USA, where decreasing trends are recorded during the last two decades. Meteorological factors modify particulate matter variations at local and regional levels. PM_2.5/PM₁₀ ratio provides information of particulate matter sources under different environment conditions. Crustal matter, road traffic and combustion of fuels are major sources of particulate matter pollution. Health studies indicate that long-term exposure to particulate matter has multiple health effects in people from all age groups. Identification of possible sources and their control with regular epidemiological monitoring could decrease the impact of particulate matter pollution.     

Strength and durability assessment of concrete containing dolomite quarry waste as fine aggregate

Journal of Material Cycles and Waste Management - The present study focuses on utilizing stockpiled dolomite quarry waste for sustainable and cleaner production of concrete. Natural river sand is...     

Induced responses to herbivory in the Neotropical ant-plant association between Azteca ants and Cecropia trees: response of ants to potential inducing cues

Plant defense against herbivores often involves constitutive and inducible mechanisms of resistance. Obligate ant-plants, which provide food and housing for ants, are thought to primarily rely on ants for defense against herbivores. This form of plant defense has largely been viewed as static. We have been investigating the dynamic nature of Azteca ants as an inducible defense of Cecropia trees. Ants rapidly recruit to and patrol sites of foliar damage. We propose that Azteca ants can be viewed as an inducible defense for Cecropia trees because of their sensitivity to cues associated with herbivory, their rapid and aggressive recruiting ability, and their reclaimable and redeployable nature as a plant defense. In this study, we examine ant behavior following plant damage, and the potential cues that indude ant recruitment. We found that ants present on leaves when the plant is damaged leave the damaged leaf and recruit other ants to it, presumably by laying recruitment trails. Volatile leaf cues associated with herbivory were important in eliciting an induced response in two experiments. However, we found that cues associated with a congeneric plant elicited a much stronger ant response than conspecific cues. Although the type of leaf damage (gaping wounds versus leaf edge wounds) did not affect the level of ant recruitment, the extent of damage did. Leaves with one hole punched showed a 50% increase in ants, while leaves with five holes punched in them elicited a 100% increase in ant numbers. In sum, it appears that multiple plant-related cues associated with herbivory are involved in induction of ant recruitment in the Cecropia-Azteca system. We discuss the generality of ant responses to herbivory in obligate ant-plant systems, and in facultative ant-plant associations, which may be more common. Received: 23 March 1998 / Accepted after revision: 5 July 1998