Adaptive QoS scheduling in wireless cellular networks

Quality of service (QoS) has been always controversial in resource shared networks. Scheduling as a packet prioritizing mechanism at Data Link Layer (DLL) contributes to QoS guarantee provisioning significantly. In this paper, a novel packet scheduler is developed in wireless cellular networks. The proposed scheme provides QoS-guaranteed service for the applications running on the sensor nodes in all the three aspects of QoS, i.e. data rate, packet loss and packet delay with regard to jitter simultaneously. We establish a three-dimensional space with certain basis vectors for QoS and introduce the efficient point of performance in terms of QoS provisioning in that space. Then we develop a generalized metric, the QoS-deviation, which is the Euclidean distance between the QoS work point of flows and the QoS efficient point in the proposed space. Based on this metric, a novel scheduling approach, namely AQDC, is designed which makes it possible to tune the trade-off between QoS provisioning and throughput optimization in an adaptive manner depending on the current Cell QoS-deviation level (CDL). Furthermore, we also develop another scheduler, namely ARTC, which is the residual-time version of the AQDC scheduler. Finally, a QoS-deviation-based CAC policy will be introduced which can be applied to all schedulers without any consideration about their structure and can be employed in cellular packet switched networks.     

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.     

Prediction of the condensed phase heat of formation of energetic compounds

A new reliable simple model is presented for estimating the condensed phase heat of formation of important classes of energetic compounds including polynitro arene, polynitro heteroarene, acyclic and cyclic nitramine, nitrate ester and nitroaliphatic compounds. For CHNO energetic compounds, elemental compositions as well as increasing and decreasing energy content parameters are used in the new method. The novel correlation is tested for 192 organic compounds containing complex molecular structures with at least one nitro, nitramine or nitrate energetic functional groups. This work improves the predictive ability of previous empirical correlations for a wide range of energetic compounds. For those energetic compounds where group additivity method can be applied and outputs of quantum mechanical computations were available, it is shown that the root mean square (rms) deviation of the new method is lower.     

Experimental and Numerical Investigation of Mixed-Mode Interlaminar Fracture of Carbon-Polyester Laminated Woven Composite by Using Arcan Set-up

Composite materials are widely used in marine, aerospace and automobile industries. These materials are often subjected to defects and damages from both in-service and manufacturing process. Delamination is the most important of these defects. This paper reports investigation of mixed-mode fracture toughness in carbon–polyester composite by using numerical and experimental methods. All tests were performed by Arcan set-up. By changing the loading angle, α, from 0° to 90° at 15° intervals, mode-I, mixed-mode and mode-II fracture data were obtained. Correction factors for various conditions were obtained by using ABAQUS software. Effects of the crack length and the loading angle on fracture were also studied. The interaction j-integral method was used to separate the mixed–mode stress intensity factors at the crack tip under different loading conditions. As the result, it can be seen that the shearing mode interlaminar fracture toughness is larger than the opening mode interlaminar fracture toughness. This means that interlaminar cracked specimen is tougher in shear loading condition and weaker in tensile loading condition.     

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.     

New approach to bone tissue engineering: simultaneous application of hydroxyapatite and bioactive glass coated on a poly(L-lactic acid) scaffold

A combination of bioceramics and polymeric nanofibers holds promising potential for bone tissue engineering applications. In the present study, hydroxyapatite (HA), bioactive glass (BG), and tricalcium phosphate (TCP) particles were coated on the surface of electrospun poly(L-lactic acid) (PLLA) nanofibers, and the capacity of the PLLA, BG-PLLA, HA-PLLA, HA-BG-PLLA, and TCP-PLLA scaffolds for bone regeneration was investigated in rat critical-size defects using digital mammography, multislice spiral-computed tomography (MSCT) imaging, and histological analysis. Electrospun scaffolds exhibited a nanofibrous structure with a homogeneous distribution of bioceramics along the surface of PLLA nanofibers. A total of 8 weeks after implantation, no sign of complication or inflammation was observed at the site of the calvarial bone defect. On the basis of imaging analysis, a higher level of bone reconstruction was observed in the animals receiving HA-, BG-, and TCP-coated scaffolds compared to an untreated control group. In addition, simultaneous coating of HA and BG induced the highest regeneration among all groups. Histological staining confirmed these findings and also showed an efficient osseointegration in HA-BG-coated nanofibers. On the whole, it was demonstrated that nanofibrous structures could serve as an appropriate support to guide the healing process, and coating their surface with bioceramics enhanced bone reconstruction. These bioceramic-coated scaffolds can be used as new bone-graft substitutes capable of efficiently inducing osteoconduction and osseointegration in orthopedic fractures and defects.     

Comparisons of the L- and LH-moments in the selection of the best distribution for regional flood frequency analysis in Lake Urmia Basin

Design flood estimation is an important task that is required in the planning and design of many civil engineering projects. Finding the most suitable distribution to flood samples and selecting the appropriate parameter estimation method are of great importance for flood frequency analysis. In this study, L-moments and LH-moments have been used to characterise the upper part of distributions and larger events in flood data. Three extreme value distributions, that is, generalised extreme value (GEV), generalised logistic (GLO) and generalised Pareto (GPA), through different levels of the LH-moments have been applied to describe the annual maximum flood data obtained from 34 sites in Lake Urmia Basin, northwest Iran. The performances of these distributions have been assessed by evaluating the relative root-mean-square error and the minimum L-kurtosis difference criterion. The result shows that the LH-moments are more efficient for obtaining improved values of flood peaks than the L-moments. For the upper part of distributions, the GEV distribution using the L2-moment is the best, followed by the GLO distribution using the L1-moment and the GPA distribution using the L3-moment. The GLO distribution using the L-moments methods is the best among all distributions for a complete data series.     

A new pushover procedure for two‐way asymmetric‐plan tall buildings under bidirectional earthquakes

Conventional pushover analyses despite of extensive applications are unable to estimate the general responses of asymmetric‐plan tall buildings because of ignoring the effects of higher modes and torsion. A consecutive modal pushover procedure is one of the recent nonlinear static pushover procedures that used to analyse the seismic response of one‐way asymmetric‐plan tall buildings under one‐directional seismic ground motions. In this paper, a modified consecutive modal pushover procedure (MCMP) has been proposed to estimate the seismic demands of two‐way asymmetric‐plan tall buildings under two horizontal components of earthquakes simultaneously. The accuracy of the MCMP procedure is evaluated using different buildings and comparing with the results of FEMA (Federal Emergency Management Agency) procedures, the practical modal pushover procedure and nonlinear time history analyses as an exact solution. The results show the proposed MCMP procedure is able to estimate the displacements and storey drifts accurately and introduces a great improvement in predicting the plastic hinge rotations. Copyright © 2013 John Wiley & Sons, Ltd.     

High‐speed blind speech separation using FICS method

In this paper, we introduce the fusion of iterative and closed‐form separation (FICS) method for high‐speed separation of mixed speech signals. This method is performed in two stages: (i) iterative‐form separation and (ii) closed‐form separation. This algorithm significantly improves the separation quality simply by incorporating only some specific frequency bins into computations. We apply the FICS method to the frequency‐domain independent component analysis (ICA) to evaluate its performance in increasing the signal separation speed. Simulation results show that for speech signals, the proposed algorithm is on average 40 times faster than the ICA, while preserving the separation quality. Also, it outperforms the FastICA, JADE, and SOBI in terms of separation quality. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Supplier selection using revised multi-segment goal programming model

Selecting the best supplier has been turned into a strategic subject in the competitive market, in the recent years. Supplier selection is one of the significant multiple criteria decision-making problems, which is studied in this paper. This research applies the multi-segment goal programming formulation, which considers different positions in the goal programming. This new kind of goal programming is revised in this investigation. The advantage of the proposed method is that it allows decision makers to set multiple aspiration levels for the coefficient of variables. Hence, the decision makers obtain more revenue and match with the reality of their problems. Unlike the multi-segment goal programming proposed in the literature, the revised formulation is linearized in the current study. The supplier selection problem is solved by this new formulation in a special circumstance. Finally, some concluding notes are remarked.