Design of hydraulic structures considering different sheetpile configurations and flow through canal banks

This research investigated seepage under hydraulic structures considering flow through the banks of the canal. A computer model, utilizing the finite element method, was used. Different configurations of sheetpile driven under the floor of the structure were studied. Results showed that the transverse extension of sheetpile, driven at the middle of the floor, into the banks of the canal had very little effect on seepage losses, uplift force, and on the exit gradient at the downstream end of the floor. Likewise, confining the downstream floor with sheetpile from three sides was not found effective. When the downstream floor was confined with sheetpile from all sides, this has significantly reduced the exit gradient. Furthermore, all the different configurations of the sheetpile had insignificant effect on seepage losses. The most effective configuration of the sheetpile was the case when two rows of sheetpiles were driven at the middle and at the downstream end of the floor, with the latter sheetpile extended few meters into the banks of the canal. This case has significantly reduced the exit gradient and caused only slight increase in the uplift force when compared to other sheetpile configurations. The present study suggests that two-dimensional analysis of seepage problems underestimates the exit gradient and uplift force on hydraulic structures.     

Geochemical and isotopic evolution of groundwater in the Wadi Watir watershed,Sinai Peninsula,Egypt

The Wadi Watir delta in the Wadi Watir watershed is a tourist area in the arid southeastern part of the Sinai Peninsula, Egypt, where development and growth of the community on the delta are constrained by the amount of groundwater that can be withdrawn sustainably. To effectively manage groundwater resources in the Wadi Watir delta, the origin of groundwater recharge, groundwater age, and changes in groundwater chemistry in the watershed needs to be understood. Mineral identification, rock chemistry, water chemistry, and the isotopes of hydrogen, oxygen, and carbon in groundwater were used to identify the sources, mixing, and ages of groundwater in the watershed and the chemical evolution of groundwater as it flows from the upland areas in the watershed to the developed areas at the Wadi Watir delta. Groundwater in the Wadi Watir watershed is primarily from recent recharge while groundwater salinity is controlled by mixing of chemically different waters and dissolution of minerals and salts in the aquifers. The El Shiekh Attia and Wadi El Ain areas in the upper Wadi Watir watershed have different recharge sources, either from recharge from other areas or from different storm events. The downgradient Main Channel area receives groundwater flow primarily from the El Shiekh Attia area. Groundwater in the Main Channel area is the primary source of groundwater supplying the aquifers of the Wadi Watir delta.     

Efficacy of Fine-Grained Soil as Landfill Liner Material for Containment of Chrome Tannery Sludge

This paper evaluates the potential use of a fine-grained soil obtained from a site in West Bengal, India, as a suitable landfill liner material for the containment of hexavalent chromium from tanning waste sludge. The physico-chemical properties of the soil were determined. The soil adsorption affinity for hexavalent chromium was also assessed through adsorption batch and breakthrough column tests. The zero point charge (pH_zpc) of the soil was found to be 7.3. The batch kinetics and column tests results indicated that the soil liner possesses a relatively good hexavalent chromium adsorption capacity at natural or slightly alkaline condition. The adsorption results showed that the hexavalent chromium uptake by the soil follows both Langmuir and Freundlich adsorption isotherms. This study also illustrated that the hexavalent chromium breakthrough curve in the column experiment reached equilibrium concentration after 3.5 pore volumes (900 h). Overall, this study showed that the fine-grained soil has the potential for usage as a landfill liner or as a component of a landfill barrier system to prevent chromium contamination from the tannery waste disposal.     

Vegetation and Climate Reconstruction of the Planalto in Rio Grande do Sul, South Brazil (Late Glacial and Holocene)

1IntroductionThe ecosystem of Araucaria-Forest is one of the most important plant-associations in South Brazil. Today,however,the spreading area is a fraction of its natural size,originally spread over 200 km. It spanned from 18°to 30°of southern lati-t…     

Markov stochastic technique to determine galactic cosmic ray sources distribution

A new numerical model of particle propagation in the Galaxy has been developed, which allows the study of cosmic-ray production and propagation in 2D. The model has been used to solve cosmic ray diffusive transport equation with a complete network of nuclear interactions using the time backward Markov stochastic process by tracing the particles’ trajectories starting from the Solar System back to their sources in the Galaxy. This paper describes a further development of the model to calculate the contribution of various galactic locations to the production of certain cosmic ray nuclei observed at the Solar System.     

Effect of exo-polysaccharides producing bacterial inoculation on growth of roots of wheat (Triticum aestivum L.) plants grown in a salt-affected soil

Effect of soil salinity on physico-chemical and biological properties renders the salt-affected soils unsuitable for soil microbial processes and growth of the crop plants. Soil aggregation around roots of the plants is a function of the bacterial exo-polysaccharides (EPS), however, such a role of the EPS-producing bacteria in the saline environments has rarely been investigated. Pot experiments were conducted to observe the effects of inoculating six strains of EPS-producing bacteria on growth of primary (seminal) roots and its relationship with saccharides, cations (Ca²⁺, Na⁺, K⁺) contents and mass of rhizosheath soils of roots of the wheat plants grown in a salt-affected soil. A strong positive relationship of RS with different root growth parameters indicated that an integrated influence of various biotic and abiotic RS factors would have controlled and promoted growth of roots of the inoculated wheat plants. The increase in root growth in turn could help inoculated wheat plants to withstand the negative effects of soil salinity through an enhanced soil water uptake, a restricted Na⁺ influx in the plants and the accelerated soil microbial process involved in cycling and availability of the soil nutrients to the plants. It was concluded that inoculation of the EPS-producing would be a valuable tool for amelioration and increasing crop productivity of the salt-affected soils.     

Natural environmental radioactivity and estimation of radiation exposure from saline soils

The study was conducted for the investigation of amount of radioactivity in the barren and cultivated soil of Bio saline Research Station in Pakka Anna, established by Nuclear Institute for Agriculture and Biology (NIAB) in 1990, 34 km. away from the city of Faisalabad, in the Punjab province of Pakistan. The studies were done on an area of about 100 hectares of two types of virgin and fertilized saline soils. The technique of gamma ray spectrometry was applied using HPGe (high purity germanium) gamma ray detector and a PC based MCA. Activity concentration levels due to ⁴⁰K, ¹³⁷Cs, ²²⁶Ra and ²³²Th were measured in 250 saline soil samples collected at a spacing of about 4 hectares at the depth level of 0–25 cm. with a step of 5 cm. depth. Activity concentrations ranges of the concerned radionuclides for both of the soils were as follows: ⁴⁰K, for virgin and cultivated saline soil was 500–610.2 and Bq/kg 560.2–635.6 respectively; ¹³⁷Cs, 3.57–3.63 and 1.98–5.15 Bq/kg ²³⁸U, 26.3–31.6 and 30.3–38.7 Bq/kg, and ²³²Th, 50.6–55.3 and 50.6–64.0 Bq/kg respectively. The absorbed dose rate in air lies in the region 63–73 nGyh^-1 and 68–83 nGyh^-1 for virgin and fertilized soils respectively. This indicates that this region lies in the area of higher radiation background, while comparing with the worlds’ average. The slightly higher value of dose in the fertilized farm may be due to the use of fertilizers for cultivation. Before the radiometric measurements, chemical analysis for concentration of Na, Ca and Mg was also carried out along with the measurement of electrical conductivity and pH of the soil samples.     

Dynamic instability of frames having thin-walled columns

Dynamic instability of single storey frames having thin-walled columns has been investigated. The lateral loads sustained by the frame are dynamic in character, while the axial loads are deemed to be quasi-statically applied. The analytical model employed by the authors has the capability of modelling the combined action of the two ‘companion’ local modes whose amplitudes are variable along the length of the column and any type of end conditions of the members. For given levels of axial loads sustained by the columns, the magnitudes of lateral loads causing instability can be significantly smaller than those corresponding to static buckling, provided the dynamic load is of sufficient duration. There exists, however, a threshold value of axial force carried by the columns, below which there is no elastic instability—static or dynamic. For columns with overall critical loads several times greater than the local critical load, there is no danger of elastic instability, but the deflections under dynamic lateral loads of less than 1 per cent of the axial load may reach such huge values that there is a serious danger of localized plastic collapse. It is also shown that moment frames having thin-walled columns such as those fabricated out of cold formed steel are extremely vulnerable to moderate seismic excitations.     

The roles of network embeddedness,market incentives,and slack resources in the adoption of clean technologies by firms in developing countries

Worldwide carbon dioxide emissions continue to increase driven by fossil fuel consumption and industrial discharges. Progress on carbon emission reduction requires firms to adopt clean technologies which minimize material and energy consumption. Technological change is particularly required in developing countries, where industrial emissions often lead to chronic urban pollution problems. In this study, we explore the antecedents of clean technology strategy by firms in developing countries. We combine the contingent natural resource-based view with the relational view to examine how network embeddedness, market incentives and slack resources influence adoption of clean technology. The empirical support for our hypotheses comes from data obtained from 342 firms that operated in the carbon-offset market during the years 2007 to 2009. We find that a firm’s relational network structure influences adoption of clean technologies, particularly when market incentives are low. Contrary to one of the hypotheses, the results of our paper suggest a negative relationship between a firm’s slack resources and its clean technology strategy. Our study highlights the benefits of networks in fostering adoption of clean technology in developing countries. Furthermore, we find that high market incentives (carbon price) decrease the probability of clean technology adoption, so adding to the view that firms respond to carbon-offset rules to realize high carbon revenues at the lowest cost.

Key policy insights

• High market incentives (carbon price) decrease the probability that firms in developing countries will adopt clean technology.

• This adds to concerns about the capability of the Clean Development Mechanism to deliver sustainable development.

• Even where market incentives are low, firms in developing countries are more likely to adopt clean technologies when they are embedded in a closed network of connected partners.

• To stimulate adoption of clean technology in developing countries, policy makers should focus on initiatives to facilitate partnerships between organizations operating in the carbon market and create opportunities for knowledge sharing and learning.

• By changing the policy focus to networks of organizations, the carbon market can bring about positive change in terms of shifting the firm behaviour.

     

Effect of earthquake energy input characteristics on hysteretic damper efficiency

Robust performance of hysteretic dampers, used in controlling mid‐rise buildings, against change of earthquake characteristics is investigated in this paper. A shear type ten‐storey building incorporating hysteretic dampers is studied as a model under the assumption of elastic perfectly plastic behavior for inelastic frame and damper deformations. An energy‐based damper performance index is used to evaluate damper overall efficiency. Thirty‐five earthquake records are applied and the damper strength is optimized for each earthquake record to obtain the maximum performance index or the damper efficiency. Based on the obtained numerical results it is found that, besides the effect of maximum energy input on damper efficiency, other time‐dependant properties such as energy‐based effective duration and earthquake dominant period have great influence on the damper efficiency. A factor (α), which represents the combined effect of maximum energy input, effective duration and dominant earthquake period, is also derived for the prediction of damper efficiency. Copyright © 2003 John Wiley & Sons, Ltd.