Impacts of Receding of the Lakes Located in the Arid and Semi-arid Areas on the Coastal Groundwater: Integrated Modeling and Experimental Study

The dropping of the water level of the lakes located in the arid lands leads to salt concentration increase. In this study, a combined experimental-computational method is developed to explore the effect of seawater concentration on the elevation of groundwater table and the rate of saltwater intrusion, while the lake water level is dropping. At the laboratory tank scale, we have collected experimental data by varying the saltwater concentration by 2.0 and 2.5 times its initial value while measuring the height of the groundwater table. Our simulation has shown an unexpected increase in height of groundwater by 5.0 and 13.0% relative to the head difference at the boundaries of the domain. Also, the intrusion rate of saltwater wedge increased by 2.0 and 3.0 times, respectively. We have used the verified model for a field state and found that if density variations are neglected in simulation, the calculated groundwater level is affected more than 2 times in response to fluctuation of lake water level (relative to simulations by including the effect of fluid density changes). Based on the results density variations can counteract; even reverse, the effect of water table changes. Remarkably, our simulations have shown that despite a severe decrease in the water level of a saline lake over time, the saltwater wedge has indeed intruded further because of the substantial increase in the density of the lake water due to the rising salinity. Based on the findings, to reach a reasonable result in the study of interaction between saline water of shrinking lakes with coastal groundwater, saltwater concentration as well as saline water density in the modeling must be considered.

     

Effect of Freezing on Functional and Textural Attributes of Cress Seed Gum and Xanthan Gum

Consumer habits have undergone great changes, motivated by the new social lifestyle. These changes have promoted the increase in the production of frozen foods; and as a result, many food applications of some hydrocolloids are limited due to functional loss during freezing. In this study, the effect of freezing treatments (?18 °C for 24 h and ?30 °C for 15 h) on rheological, emulsifying, foaming, and textural characteristics of cress seed gum as a new source of hydrocolloid in comparison with xanthan gum as a commercial gum were investigated. The results demonstrated that cress seed gum had significantly lower viscosity than xanthan gum solution, and the freezing treatments did not have significant impact on rheological properties of both products. Conversion of water to ice leads to an increment in molecular association and improved textural characteristics. The high tendency of cress seed gum chains to associate is attributed to its high mannose to galactose ratio. High stability of cress seed gum and similarity with xanthan gum make it attractive for use in frozen foods as a novel gum to provide specific functionality, minimize the negative effect of freezing, and reduce production costs.     

Synthesis and characterization of new thermally stable aromatic copoly(ester–amide)s from diester‐dicarboxylic acids

Two new aromatic diester‐dicarboxylic acids containing furan rings, namely, benzofuro[2,3‐b]benzofuran‐2,9‐dicarboxyl‐bis‐pyridyl ester‐4,4′‐dicarboxylic acid and benzofuro[2,3‐b]benzofuran‐2,9‐dicarboxyl‐bis‐phenyl ester‐4,4′‐dicarboxylic acid were synthesized by the reaction of benzofuro[2,3‐b]benzofuran‐2,9‐dicarbonyl chloride with 6‐hydroxynicotinic acid and 4‐hydroxybenzoic acid, respectively. These monomers were converted to aromatic copoly(ester–amide)s by reaction with various aromatic diamines via direct polycondensation. Polymers were characterized by FTIR and ¹H NMR spectroscopy, thermogravimetry, viscosity and solubility tests. The inherent viscosity of the polymers was in the range 0.23–0.46 dl g^?1 in dimethyl sulfoxide at 30 °C. They dissolved readily in polar solvents at room temperature. They possess a glass‐transition temperature in the range 210–260 °C and exhibit excellent thermal stability. Copyright © 2004 Society of Chemical Industry     

International Environmental Conflict Management in Transboundary River Basins

Despite signing a bilateral water treaty in 1973, water utilization in the Hirmand River Basin (HRB) has been a source of dispute between Iran and Afghanistan for many decades. While Iran accuses Afghanistan of depriving it of the Hirmand water due to dam construction in the upper basin, Afghanistan assures that it enforces the treaty. An evident reduction of the Hirmand River flow to Iran in recent years is fully attributed by Afghanistan to a reduction in precipitation in the basin. Although Iran disagrees and remains unconvinced by this line of reasoning. A fundamental lack of trust in collected and shared hydrological data has hindered dialog between the two neighbors. To address this issue, this study investigates the use of remote sensing information, as an independent source of data, for fact-finding in a highly disputed transboundary river basin. For this purpose, historical data (34 years) from two satellite precipitation products, PERSIANN-CDR and CHIRPS, were used to understand if precipitation characteristics and, subsequently, rainfall-runoff regimes have changed in the HRB. Results reveal that the frequency and amount of heavy precipitation have been increasing over the mountainous areas. The total amount of precipitation has been increasing significantly. The intensity of heavy precipitation, however, has been decreasing over the basin. In the upper basin, the duration of the wet period has increased, although the share of wet months in annual precipitation has been decreasing. In the lower basin, trends in seasonal and annual precipitation and most of the indices are insignificant, indicating water availability issues cannot be attributed to the changes in precipitation in the downstream area itself. These results can be used as an integral part of mutual fact-finding and trust-building exercise that supports water diplomacy to promote environmental cooperation between Iran and Afghanistan.

     

Distributed Object–Oriented Blackboard Model for Integrated Design of Steel Structures

Distributed computing on a cluster of workstations connected via a local area network provides a cost–effective approach to high–performance computing. The goal of this research is to lay the foundation for developing maintainable, extendable, and reusable programmer–defined object–oriented software systems on a cluster of networked workstations. A distributed object–oriented blackboard model (OOBM) is presented for integrated design of large structures on a cluster of workstations. The model includes an object–oriented alternative to model the functions of message passing and process control required in a distributed processing environment. The operational idea behind the distributed OOBM is to perform two missions iteratively until the desired solution is found. The first mission is to pass and monitor data messages through network communication using a network file server. The second mission is to generate a number of processes at heterogeneous workstations using appropriate process–generating models and techniques. The models and concepts developed in this research are applied to the problem of integrated design of steel structures.     

Resource Scheduling Using Neural Dynamics Model of Adeli and Park

This paper presents a mathematical model for resource scheduling considering project scheduling characteristics generally ignored in prior research, including precedence relationships, multiple crew-strategies, and time cost trade-off. Previous resource scheduling formulations have traditionally focused on project duration minimization. The proposed model considers the total project cost minimization. Furthermore, resource leveling and resource-constrained scheduling have traditionally been solved independently. In the new formulation, resource leveling and resource-constrained scheduling are performed simultaneously. The proposed model is solved using the patented neural dynamics model of Adeli and Park. A case study is presented to demonstrate the performance of the method under various resource availability profiles.