Revista de Ingeniería Civil y Ambiental

Most of the mobile phone antennas are located in urban areas. An economical solution is to place the antennas on top of existing buildings. In practice, any effect that the building has on the antenna wind load is neglected. Wind tunnel investigations and numerical simulations show that the wind loading might increase in some cases by up to 30% compared with the free flow.

This article presents the quality requirements for bioethanol using as a biofuel or a gasoline blend. There were discussed the blends of gasoline with bioethanol. Then, there was characterized the properties of ethanol in direction its use as a biofuel. Next, there were discussed both benefits and difficulties resulting from its use. Then, for comparison there was described the possibility of using methanol and heavy alcohols as biofuels.

Bus dwell time (DT), which is defined as the time interval between the opening and closing its doors to serve passengers at the bus stop, is an important element in improving the travel time between end terminals of bus routes. DT on bus routes in dense urban areas varies by time of day. Also, DT could be measured or estimated using mathematical models. This study aimed at developing innovative DT models for bus stops located in dense urban areas taking in consideration the bus stop type (located near intersections and at mid-blocks), and by time of the day (morning, mid-day and evening). The models were developed using simple ordinary least squares methods with all statistical inferences at 95% confidence interval. The results of the data analysis showed that DT, on average, was higher at bus stops near intersections than those at mid-blocks. The models obtained for DT were determined to be statistically significant at 95% confidence level, based on the R2, F-Statistic and model validation tests. The Kolmogorov-Smirnoff, normal probability and residual plots were used to confirm the adequacy of the models. The analysis also revealed that the models were significantly different by time of day and by bus stop type. It should also be noted that the models were based on bus transit operation in a dense urban area and may not be appropriate for predicting DT in non-similar settings.

This study uses a layered elastic analysis and a computational model to evaluate the fatigue life of the base layer stabilized with conventional bitumen 60/70 compared with a base layer stabilized with high modulus bitumen 13/22 for a lifetime of 20 years. This study makes a comparative between conventional bitumen and high modulus asphalt concrete in terms of fatigue or cycles to failure of both asphalts at 15°C. The result of this study shows that HMAC 13/22 has much longer fatigue life compared with conventional bitumen 60/70, in some cases even four times longer; the lifetime of the pavement increases considerably with the use of HMAC in the base layer of pavement according to mechanical calculations. HMAC raise elastic modulus of middle layer. HMAC can also improve stress state of pavement structure, reduce shear strain and asphalt pavement rutting.

The use of Fiber Reinforced Polymer (FRP) bars to reinforce concrete structures has received a great deal of interest in recent days due to their high tensile strength, corrosion resistance and good non-magnetization properties. Whether to pick FRP bars due to their low modulus of elasticity over conventional steel, to be used in beams, is the major concern of a designer. FRP bars show low strength in shear as they are more elastic than steel. Recently, researchers have developed a number of models to predict the shear strength of FRP-reinforced concrete, but none of them have yet been capable of determining the results satisfactorily. Here a comparative study among different codes and models as suggested by the researchers has been conducted to predict the shear strength of FRP reinforced concrete beams. To facilitate the comparison a database of 104 beams have been presented, which are composed of shear span-to-depth ratio, a/d ranged from 2.5 to 6.5, shear span, (a) ranges from, 600 to 1219, concrete compressive strength, (fc’) 24.1Mpa to 81.4MPa, Modulus of elasticity of FRP bars, (Ef) varies between 32GPa to 145GPa, longitudinal reinforcement ratio, (Pf) varies between 0.25 to 3.02. The database contains beams and slabs without transverse reinforcement. The guidelines, codes and models that have been implemented and compared in this study consist of ACI 440.1R-03, CSA S806-06, CSA S806-08, CSA S806-11, JSCE-1997, ISIS-M03-01 2001, BISE guideline 1999. It was observed from the statistical analysis that model proposed by Kara 2011 exhibited the overall best performance to predict the shear strength of FRPreinforced beams.

Nowadays the greatest crisis faced by the construction industry is the availability of sand. As the digging of river sand destroys the river bed and causes danger for people using the river, digging of river sand has been made illegal in most rivers. So getting river sand is really expensive nowadays as its availability is very limited. So more importance is now given nowadays for replacement of river sand as fine aggregate. Mostly used nowadays in Kerala is M-Sand. In our project we are trying to replace sand with crushed used (demolished) concrete. The concrete created with this aggregate showed almost the same strength of concrete with natural sand. This is not only much cheaper than river sand and M sand, but also helps to decrease the disposal of construction wastes, which environmentalists say degrades the land. So in the end use of this crushed concrete is beneficial not only to the contractor but also to our environment. This is an experimental study to see the feasibility of C&D wastes as fine aggregate in concrete.

Current approaches to quantify groundwater depletion due to poor management are water balance and Satellite gravity approaches. However, Water balance technique includes uncertain estimation of its parameter such as Eva transpiration and runoff. Satellite gravity method consumes time and effort. This work proposes using parametric life time techniques in a novel way to predict groundwater saturated thickness depletion. One of the most important issues in the failure theory proposed is to determine the failure point (depletion case). The proposed technique uses depth of water as the net result of recharge/discharge process in the aquifer, to calculate remaining saturated thickness resulted from the applied pumping rates in an area to evaluate the depletion. The two parameters Weibull function and Bayes analysis used to model and analyze the collected data. An illustrative example of the proposed methodology was carried out in a nonrenewable aquifer, no recharge; consequently the continuous decline in water depth is the main criterion to estimate the depletion. The value of the proposed approach is to predict the probable effect of the currently applied pumping rates on the saturated thickness with time based on the obtained remaining saturated thickness data especially on nonrenewable system. The limitation of the suggested approach is that it assumes the applied management practices are constant during the prediction period. Moreover, there is no major climate change. With further studies and applications the suggested method could be promising in prediction in different aspects of hydrology field.

The mountainous region in the north of the United Arab Emirates (UAE) and Oman features intermittent streams called wadis which are generally dry but flow seasonally or temporarily. This region is characterized by high peaks and carbonate rocks. The main objective of the present study is to identify drainage network types for fifteen wadis in this northern region of the UAE and Oman. The slope of preexisting surfaces (preexisting slope) is also estimated to determine whether the preexisting slope affects the development of wadi networks. Drainage network types are determined by using three scaling-invariance measures: the drainage area increments, the channel course irregularity, and the tributary junction angle. The slope of preexisting surfaces is estimated based on small drainage areas and Laplace curvatures that are close to zero. In this study, thirteen wadis are classified as rectangular networks and two wadis are classified as parallel networks. Parallel networks are found to occur on steep preexisting slopes similarly to other regions in the world. Rectangular networks are also found to develop on steep preexisting slopes, whereas in other locations, such as in the USA, the same network type occurs on gentle preexisting slopes. This indicates that the development of rectangular networks in the region may be unaffected by preexisting slopes.

Adsorption technique is widely used for removal of toxic organic contaminants from aqueous streams. Owing to the hazardous or otherwise undesirable characteristics of phenolic compounds in particular, their presence in wastewater from municipal and industrial discharge is one of the most important environmental issue. The discharge of poor quality effluents by the chemical-based laboratories and refineries in India is posing a serious threat to water sources and wastewater treatment installations alike. Our study was set up in the Indo-French Unit for Water and Wastewater Technologies (IFUWWT), IIT Delhi. The main objective of this study was to assess the efficiency of a laboratory-scale activated sludge treatment process in producing a final effluent conforming to regulatory standards of Central Pollution Control Board, India (CPCB norms) with regards to COD and metal ion loads. The study was conducted in three principal stages: characterization of wastewater containing nanoparticles; treatability studies of laboratory generated discards and investigations of heavy metal ions before and after treatment. The various raw effluent parameters analyzed were COD, BOD, F/M ratio, Sludge Value Index, Total Solids and concentrations of Cu, Ag and Zn. Studies were conducted using two aerobic Sequencing Batch Reactors (SBR). MLSS of the aeration basin was calculated to be 7180 ± 261.3 mg/L while the F/M ratio was kept down to 0.1560 ± .0149; besides, an SVI of 107.24 mL/g complied with the state of bioreactor’s sludge. These set of values suggested to set an extended aeration processes for the reactors. Accordingly, the detention time in aeration basin was 24 hours. The results showed over 98% influent COD reduction and nearly 100% removal of metal ions. The sample used was operated on sludge collected from Vasant Kunj Wastewater Treatment plant. Based on the results from waste characterization and treatability studies, it was decided that the mixed liquor discharged in the activation tank should have glucose solution and laboratory discarded sample in 1:1 ratio. The reactor was operated on a glucose fed batch basis for 30 days. For the sake of metal analysis, the digested water samples were analyzed for the presence of copper, silver and zinc using the Element AS AAS4141 atomic adsorption spectrophotometer (by Electronics Corporation of India Ltd). The Biosorption capacities were found to be over 95% in all the cases with the minimum correlation coefficient for calibration curve being 0.9811. Such a high sludge yield is suggestive of the fact that heavy metals are in very low concentrations in the considered carboy sample. Because of these insignificant values, the amount of metal ions introduced to the system gets adsorbed almost completely, hence leaving behind no metal ion within the supernatant. Well-treated wastewater has enormous potential as a source of water for crops, households and industry.