A routing layer-based hierarchical service advertisement and discovery for MANETs

The implementation of mobile ad hoc networks (MANETs) is steadily increasing. MANETs are especially popular in locations that lack a fixed communication infrastructure. To achieve zero-configuration MANETs, as well as quick and easy access to network resources, resources must be well managed by the network. This paper proposes a hierarchical service discovery and advertisement protocol (HSDAP) implemented in the routing layer. HSDAP queries services by piggybacking service REQuest (SREQ) packets on routing packets to reduce overhead and energy consumption. We extend the cluster-based routing protocol (CBRP) to improve service management hierarchy. Simulation results show that adding service discovery and advertisement (SDA) functions to CBRP does not significantly affect overhead. SDA overhead, routing overhead, energy consumption, and SDA delay are significantly less than the extended zone routing protocol. Furthermore, SDA hit ratio of the proposed protocol is greater than 86% for various levels of mobility. The proposed HSDAP is robust and scalable.     

Performance evaluation of a continuous bipolar electrocoagulation/electrooxidation-electroflotation (ECEO-EF) reactor designed for simultaneous removal of ammonia and phosphate from wastewater effluent

The present study aimed to evaluate the performance of a continuous bipolar ECEO-EF reactor designed for simultaneous removal of ammonia and phosphate from wastewater effluent. The reactor was comprised of two distinct units: electrochemical and separation. In the electrochemical unit, Al, stainless steel, and RuO₂/Ti plates were used. All the measurements were performed according to the standard methods. Maximum efficiency of the reactor for phosphate removal was 99% at pH of 6, current density of 3 A, detention time of 60 min, and influent phosphate concentration of 50 mg/l. The corresponding value for ammonia removal was 99% at a pH of 7 under the same operational conditions as for phosphate removal. For both phosphate and ammonia, the removal efficiency was highest at neutral pH, with higher current densities, and with lower influent concentrations. In addition to removal of phosphate and ammonia, application of the Al³⁺ plates enabled the removal of nitrite and nitrate, which may be present in wastewater effluent and are also products of the electrochemical process. The reactor was also able to decrease the concentrations of phosphate, ammonia, and COD under actual wastewater conditions by 98%, 98%, and 72%, respectively. According to the results of the present study, the reactor can be used for efficient removal of ammonia and phosphate from wastewater.     

Potential of a desiccant-evaporative cooling system performance in a multi-climate country

In this paper, a desiccant-evaporative cooling system introduced and applied to a Ventilation and Makeup mode operating cycle. Desiccant part of hybrid cooling system is a heat driven component and effective in area where the use of thermal energy is more economical than electrical power. First, mathematical model of desiccant component based on transient and coupled heat and mass transfer derived. Then the hybrid system model applied to predict the system performance under various operational conditions. The numerical results validated using experimental measurements. The effects of various outdoor design conditions on COP and output of hybrid cycle temperature presented in contour plot forms. Based on these contour plots, COP and output cycle temperature can easily obtain under various ambient conditions. In addition, the potential of presented hybrid desiccant-evaporative cooling system to provide thermal comfort in various outdoor design conditions evaluated and compared with direct and direct-indirect evaporative cooler. The results show these systems are more effective than direct and direct-indirect evaporative cooling systems and provide a better thermal comfort even in hot and humid area. Moreover, introduced systems successfully provide better thermal comfort condition in a multi-climate country (Iran) especially in the area where the evaporative coolers are not applicable.     

Investigation on the bond strength of Al-1100/St-12 roll bonded sheets,optimization and characterization

Al-1100/St-12 aluminum clad steel sheets were produced using roll bonding process at different reductions in thickness and with various supplemental annealing treatments. Experiments were conducted by applying the Taguchi method to obtain optimum condition for maximizing the joint strength. The joint strengths of the bi-layer sheets were evaluated by peel test. The Al/Fe intermetallic phases at the joint interface and the peeled surfaces were examined using scanning electron microscopy (SEM). Energy dispersive spectroscopy (EDS) and Vickers microhardness test were performed to characterize the intermetallic compounds. The results indicate that at the optimum condition of 0.50 reduction in thickness, 450 °C annealing temperature and 90 min annealing time, the bond strength reaches to the base aluminum sheet strength. In comparison to the reduction in thickness and annealing time, the annealing temperature has the most influence on the joint strength changes. In general, raising the annealing temperature up to 450 °C, increases the joint strength. However, annealing treatment at 500 °C reduces the strength due to the formation of brittle Al/Fe intermetallic layer at the bond interface. Additionally, increasing the reduction in thickness improves the joint strength.     

A new approach to predict the strength of high energy materials

This paper presents a new approach to predict the strength of energetic compounds in which there are important classes of high explosives including nitroaromatics, acyclic and cyclic nitramines, nitrate esters and nitroaliphatics. For C(a)H(b)N(c)O(d) compounds, the ratio of carbon to oxygen atoms and the predicted heat of detonation on the basis of the H(2)O-CO(2) arbitrary have been used to calculate the strength of an explosive. The new model can give good predictions for mentioned energetic compounds as determined by the Trauzl test. The novel correlation will be useful in predicting the strength or power of a new energetic compound that has significant potential in the field of explosives and propellants.     

Dietary assessment of hemodialysis patients in Tehran, Iran

Inadequate dietary intakes are a major determinant of malnutrition in hemodialysis (HD) patients. Considering the lack of information available on dietary intakes of HD patients in Iran, the present study was designed to assess the dietary intakes of HD patients in Tehran, Iran. For this cross‐sectional study, from among adult HD patients of 50 Tehran hemodialysis centers, 291 patients were randomly selected. Dietary intakes of these patients were assessed using a 4‐day dietary recall. In addition, 4 mL of blood was obtained from each patient before dialysis to measure serum urea, creatinine, albumin, phosphorus, calcium, potassium, and high sensitive C‐reactive protein levels. Dietary intakes of energy, protein and fiber were lower than recommended intakes in 88%, 84.5%, and 99% of HD patients, respectively. There were significant associations between dietary energy intake with the patient's age (p < 0.05), and HD vintage (P < 0.001). In addition, a significant association was found between dietary protein intake and sex (P < 0.05). Intakes of vitamins B1, B2, B3, B6, B12, C, E, folic acid, and of the minerals calcium and zinc (from both the diet and supplements) were lower than recommended intakes in 13.5%, 41.5%, 19%, 66%, 61%, 78%, 77%, 24%, 34%, and 98.5% of HD patients, respectively. Inadequate intakes of energy and various nutrients are prevalent in HD patients in Tehran, Iran, which may contribute to increased morbidity and mortality in these patients. Therefore, nutrition counseling and the administration of vitamin and mineral supplements are necessary in Iranian HD patients.     

Assessment Of Noise Impacts At Airports

Airport operation is a major source of community concerns due to aircraft noise emissions particularly in locations close to airports and aircraft flight tracks. The effects of aircraft noise on humans can cause hearing damage for people working at airports and speech and sleep interference which can develop into stress for nearby communities. As such, it becomes essential when locating and designing to expand airports to optimize flight paths in a way to reduce noise exposure to nearby communities. For this purpose, it is required to assess changes in noise levels resulting from new runway configurations, evaluate increased aircraft operation demand, new fleet mix, revised routings and airspace structures, alternative flight profiles, and modifications to other operational procedures. This paper presents a noise impact assessment for the proposed expansion at the Beirut International Airport, Lebanon. Field noise measurements were collected at sensitive noise receptors along selected locations around the airport and the corresponding airport traffic flow was characterized. A mathematical model was then applied to simulate noise levels as a function of the different airplane classes, operations, flight path, and landing characteristics. The model was also used to predict future noise levels, optimize airplane flight path, and assess mitigation measures to minimize potential aircraft noise impacts.     

Simulation of concrete flow in V-funnel test and the proper range of viscosity and yield stress for SCC

The present paper highlights the flow simulation of self consolidating concrete (SCC) in V-funnel test that is used to determine the concrete filling ability and its resistance against segregation. Simulations were performed using a two-dimensional smoothed particle hydrodynamic (SPH) method to determine the discharge time where SCC was considered as a homogeneous Bingham fluid. The numerical predictions are lower than experimental data because of the assumptions of two-dimensional and homogeneous flow. Having the SPH method employed, SCCs with different viscosities and yield stresses were simulated to compare the discharge time with the suggested criteria in EFNARC (2002) and (2005) guidelines. Based on simulations results, the appropriate range of viscosities and yield stresses as well as a relation between rheological properties and discharge time for SCC taking into account EFNARC (2002) and (2005) guidelines are suggested. Using the suggested relations, one can assess the proper SCC filling ability without conducting the V-funnel test.     

Augmented ε-constraint method in multiobjective staff scheduling problem: a case study

Staff scheduling is one of the most relevant issues among production planning managers. The problem is to set up an appropriate schedule for various employees to maximize the performance measurement. There are different conflicting criteria with any scheduling problem such as cost minimization, efficiency maximization, etc. The proposed model of this paper develops a new multiobjective decision-making scheduling problem, and the resulted problem is solved using two different techniques of goal programming and augmented epsilon constraint. The implementation of the new proposed model is demonstrated with a real-world case study, and they are analyzed. The preliminary results indicate that the epsilon-constraint method somewhat performs better than goal programming technique.     

Experimental study and numerical modeling of arc and weld pool in stationary GTA welding of pure aluminum

In this study, a 2D mathematical model was developed for both arc and weld pool in stationary GTA welding. In arc model, current continuity equation has been solved in both arc and cathode regions without any assumption of fixed current density on the cathode surface which was essential in most previous works. The results of arc model were presented for both copper and aluminum anodes to investigate the effect of anode material on arc properties. It was seen that aluminum anode has lower maximum anode current density and heat flux but the distributions are wider than copper anode. Furthermore, shear stress on anode surface is higher in the case of aluminum anode. Also, calculated results of this study were compared with other available theoretical and experimental results. It has been shown that the agreement between calculated and experimental results was fairly good. The necessary information to simulate the weld pool, including the anode current density and heat flux to the workpiece were taken from the arc model. In this model, due to high thermal conductivity of pure aluminum, fluid flow into the weld pool was ignored. Effects of arc variables, i.e., arc length, applied current and welding time on the shape and size of the weld pool were investigated as well. In order to check the validity of the weld pool model, a comparison between calculated results and the results of our experimental tests was conducted. Generally, these comparisons reveal an acceptable agreement between calculated results and experimental data.