Density functional modelling studies of chloride-substituted Schiff bases as corrosion inhibitors: Optimized geometries,atomic charges,solvent and non-linear optical effects

The anti-corrosive properties, optimized geometrical structures, atomic charges, molecular electrostatic potential (MEP) surfaces and non-linear optical (NLO) effects of some chloride-substituted Schiff bases salicylaldimine (R), N-(2-chlorophenyl)salicyaldimine (2Cl–R), N-(3-chlorophenyl)salicyaldimine (3Cl–R) and N-(4-chlorophenyl)salicyaldimine (4Cl–R) have been investigated by using density functional modelling calculations. The quantum chemical parameters, such as the highest occupied molecular orbital, the lowest unoccupied molecular orbital, gap energy and other parameters, including electronegativity, global hardness, the total charges on the whole molecules and the total energies have been calculated and discussed to obtain information about the relationships between the molecular and electronic structures of the studied inhibitors and their experimental corrosion inhibition efficiencies. The linear polarizability (α), and the firstorder hyperpolarizability (β) have been also predicted by the density functional theory (DFT) with different base sets 6-31G(d), 6-31+G(d,p), 6-31++G(d,p), 6-311+G(d) and 6-311++G(d,p) for investigating the effects of basis sets on the NLO properties.     

3D Modeling of Ripping Process

Due to environmental constraints and limitations on blasting, ripping as a ground loosening and breaking method has become more popular than drilling and blasting method in both mining and civil engineering applications. The best way of estimating the rippability of rocks is to conduct direct ripping runs in the field. However, it is not possible to conduct direct ripping runs in all sites using different dozer types. Therefore, the utilization of numerical modeling of ripping systems becomes unavoidable. A complex ripping system can better be understood with three-dimensional (3D) models rather than two-dimensional models. In this study, 3D distinct element program called 3DEC was used to investigate the ripping process. First, the ripping mechanisms were investigated and then the individual factors that affect the rippability performance of dozers were reviewed. The rippabilities of rocks depend not only on the rock properties, but also machine or dozer properties. Thus, ripper production and rock rippability with D8 type of dozers were also determined by direct ripping runs on different open pit lignite mines within the scope of this research. Production values obtained from numerical modeling were compared with field production values obtained from the case studies. This comparison shows that the model gives consistent and adequate results. Hence, a link has been established between the field results and the 3D models.     

Interference aware vertical handoff decision algorithm for quality of service support in wireless heterogeneous networks

Next generation wireless networks concept aims at collaboration of various radio access technologies in order to provide quality of service (QoS) supported and cost efficient connections at anywhere and anytime. Since the next generation wireless systems are expected to be of heterogeneous topology, traditional handoff (horizontal handoff/handover) mechanisms are not sufficient to meet the requirements of these types of networks. More intelligent vertical handoff algorithms which consider user profiles, application requirements, and network conditions must be employed in order to provide enhanced performance results for both user and network. Moreover, frequency reuse of one (FRO) seems to be the strongest candidate of deployment options for next generation wireless networks; therefore, interference conditions gains a significant attention in vertical handoff decision making process. In this study, a fuzzy logic-based handoff decision algorithm is introduced for wireless heterogeneous networks. The parameters; data rate, received signal strength indicator (RSSI), and mobile speed are considered as inputs of the proposed fuzzy-based system in order to decide handoff initialization process and select the best candidate access point around a smart mobile terminal. Also, in contrast to the traditional fuzzy-based algorithms, the method proposed takes ambient interference power, which is referred to as interference rate, as another input to the decision process. The results show that the performance is significantly enhanced for both user and network by the method proposed.     

Integration of a speech activated control system and a wireless interworking unit for a CAN-based distributed application

Ever increasing number of mobile devices in automation systems have revealed the requirement of utilizing wireless communication systems enabling interoperability between existing wired and wireless systems. Therefore, a wireless interworking unit (WIU) is usually employed to provide required interworking functionality. This work briefly exploits a controller area network (CAN)/IEEE 802.11b WIU and a speech activated control application to be used in a CAN-based industrial networking environment and presents its prototype. The WIU employed provides communication skills with the speech activated control system including a speech recognition process and CAN-based distributed control application over the wireless medium.     

Displacement induced fatigue cracks

The interaction of the various components of a bridge structure under regular truck or train traffic has frequently resulted in cracking in unexpected locations in relatively short periods of time. In welded girder type bridges this cracking has often occurred in the web at short gaps between transverse connection plates and the girder flanges. This paper examines two cases of fatigue cracking at such short gap conditions. Strain measurements and a detailed analysis are used to demonstrate that such cracking results from the out-of-plane movements of the web in the short gap region. The study demonstrates that the most reliable means of preventing this type of cracking is to connect the transverse connecting plates to both top and bottom flanges.     

A new MAC protocol for broadband wireless communications and its performance evaluation

This paper presents a new Time Division Multiple Access/Frequency Division Duplexing (TDMA/FDD) based Medium Access Control (MAC) protocol for broadband wireless networks, supporting Quality of Service (QoS) for real-time multimedia applications. It also gives the Call Blocking Probability (CBP), packet end-to-end delay and utilization analysis of different service classes, as they are most essential performance criterions in broadband wireless network assessment. The Connection Admission Control (CAC) mechanism in the proposed MAC efficiently organizes the bandwidth allocation for different service classes by means of a fairness based scheduling algorithm. In addition, the simulation model of the proposed MAC scheme is realized by using OPNET Modeler network simulator. The results of the analytical calculations for the CBPs are compared to those of the simulation of the proposed MAC, thus validity of the MAC protocol is proved.     

Optimization of folded plate roofs

Increased usage of prefabricated structural components and the advantages offered by folded plate roofs necessitates the optimization of their configurations. In order to reduce the material expenditure, transportation and erection costs the dead-weight of the roof systems need to be minimized.The reported study defines a technique for the optimization of the structural weight of the folded plate roof without intermediate stiffeners and subjected to one loading system. The developed method enabled the generation of the different, and consequently the optimum, geometries by starting with an arbitrary initial geometry. The azimuthal angles, the width and the thickness of the individual panels were permitted to vary. The optimization employed a variational approach and flexibility formulation. The total weight of the roof was taken as the target function, subject to minimization. The equilibrium equations for the panels were taken as the constraint equations for the optimization process. The pseudo-weight function was established through the use of the Lagrangian multipliers. The standard Lagrangian formulation was then applied to the pseudo-weight function, and a set of optimization equations were generated. These equations, along with the original equilibrium equations, formed a system of simultaneous nonlinear transcendental equations. This set was solved using an iterative approach.The overall formulation was kept general enough to permit the inclusion of any given loading condition to permit the application of the given methodology to any folded plate roof system.     

Neural models for an asymmetric coplanar stripline with an infinitely wide strip

This paper presents a new approach, based on artificial neural networks (ANNs), to determine the characteristic impedance and the effective permittivity of an asymmetric coplanar stripline (ACPS) with an infinitely wide strip. ANNs are trained with five learning algorithms to obtain better performance and faster convergence with simpler structure. The best results for training and test were obtained from the models trained with the Levenberg–Marquardt and the Bayesian regularization algorithms. The results obtained by using the neural model are in very good agreement with the results available in the literature. The neural models presented in this work provide simplicity and accuracy to determine both the parameters of an ACPS. The method is not time consuming and is easily included in a CAD system.