Locational analysis for regionalization of Turkish Red Crescent blood services

After a series of earthquakes in 1999, Turkish Red Crescent (TRC) has engaged in a restructuring for all of its activities, including the blood services. Our study on the blood management system had been started as part of this initiative to restructure the blood services and improve both their effectiveness and efficiency. In the current system of TRC, not much consideration has been given to how the locational decisions affect the performance of blood centers, stations and mobile units. In recent years, however, there has been much discussion regarding the regionalization of the blood management system in Turkey. In this study, we develop several mathematical models to solve the location–allocation decision problems in regionalization of blood services. We report our computational results, obtained by using real data, for TRC blood services.     

An Estimation of the Suspended Sediment Load Using Adaptive Network Based Fuzzy Inference System,Support Vector Machine and Artificial Neural Network Models

Sediment transport in streams and rivers takes two forms as suspended load and bed load. Suspended load comprises sand + silt + clay-sized particles that are held in suspension due to the turbulence and will only settle when the stream velocity decreases, such as when the streambed becomes flatter, or the streamflow into a pond or lake. The sources of the suspended sediments are the sediments transported from the river basin by runoff or wind and the eroded sediments of the river bed and banks. Suspended-sediment load is a key indicator for assessing the effect of land use changes, water quality studies and engineering practices in watercourses. Measuring suspended sediment in streams is real sampling and the collection process is both complex and expensive. In recent years, artificial intelligence methods have been used as a predictor for hydrological phenomenon namely to estimate the amount of suspended sediment. In this paper the abilities of Support Vector Machine (SVM), Artificial Neural Networks (ANNs) and Adaptive Network Based Fuzzy Inference System (ANFIS) models among the artificial intelligence methods have been investigated to estimate the suspended sediment load (SSL) in Ispir Bridge gauging station on Coruh River (station number: 2316). Coruh River is located in the northern east part of Turkey and it is one of the world”s the fastest, the deepest and the largest rivers of the Coruh Basin. In this study, in order to estimate the suspended sediment load, different combinations of the streamflow and the SSL were used as the model inputs. Its results accuracy was compared with the results of conventional correlation coefficient analysis between input and output variables and the best combination was identified. Finally, in order to predict SSL, the SVM, ANFIS and various ANNs models were used. The reliability of SVM, ANFIS and ANN models were determined based on performance criteria such as Root Mean Square Error (RMSE), Mean Absolute Error (MAE), Efficiency Coefficient (EC) and Determination Coefficient (R²).     

Extraction of voltage harmonics using multi-layer perceptron neural network

This paper presents a harmonic extraction algorithm using artificial neural networks for Dynamic Voltage Restorers (DVRs). The suggested algorithm employs a feed forward Multi Layer Perceptron (MLP) Neural Network with error back propagation learning to effectively track and extract the 3rd and 5th voltage harmonics. For this purpose, two different MLP neural network structures are constructed and their performances compared. The effects of hidden layer, supervisors and learning rate are also presented. The proposed MLP Neural Network algorithm is trained and tested in MATLAB program environment. The results show that MLP neural network enable to extract each harmonic effectively.     

Parallel-machine rescheduling with machine disruptions

In this study we consider a rescheduling problem on identical parallel machines. The rescheduling is undertaken because of a period of unavailability on one of the machines. We consider the total flow time as an efficiency measure and stability is gauged in terms of the number of jobs processed on different machines in the original and new schedules. We show that all efficient schedules with respect to efficiency and stability measures can be generated in polynomial time.     

Preparation and characterization of conductive polypyrrole/kaolinite composites

Conductive polypyrrole (PPy)/kaolinite clay composites were prepared by in situ chemical polymerization of pyrrole in the presence of kaolinite using FeCl₃ as oxidant. The PPy content and conductivity of the composites reached 32.8% and 8.3×10^?2 S/cm at HCl concentrations of 1.5 M and 0.5 M, respectively. The microhardness of the composites containing different amounts of PPy was higher than that of the PPy and kaolinite components. The highest microhardness observed was 30.17 kg/mm² for the composite containing 9.6% PPy. The electrical resistance of the composites was monitored during heating–cooling cycles over the range 5–120 °C. The change in resistance with temperature was more repeatable for the composite than for PPy. The composites were characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The humidity-sensing properties were also examined.     

Preparation of Plate‐Like Sodium Niobate Particles by Hydrothermal Method

Sodium niobate NaNbO₃ hydrate (NN‐hydrate) particles with a plate‐like morphology were prepared at 140°C for 2 h in 12 mol/L of NaOH by the hydrothermal method. Bar‐like Na₈Nb₆O₁₉·13H₂O particles were synthesized at as low as 100°C for 2 h. This work demonstrates that by carefully optimizing the reaction condition, we can selectively fabricate niobate structures, including the bar‐like, plate‐like, fibers and cube particles through a direct reaction between NaOH solution and Nb₂O₅. It was found that Nb₆O₁₉^8? formed was an important premise for formation of the NN‐hydrate, and lower [OH^–] was not favorable in preparing the NN‐hydrate as there was an optimum [OH^?]. Through researching effects of the reaction temperature, time, concentration of NaOH, and content of Nb₂O₅ on the NN‐hydrate structure and evolution, the formation mechanism from solid reactants to the intermediate were investigated. After calcining at 800°C, the synthesized NN‐hydrate particles made a phase almost transform to the perovskite NaNbO₃, and the morphology of these calcined particles was still plate‐like.     

Preparation of Morphology‐Controlled Plate‐Like Sodium Niobate Particles by Hydrothermal Synthesis

Sodium niobate (NaNbO₃) particles with plate‐like morphology and hexagonal unit cells were prepared by the hydrothermal method. The result of SEM showed that the hexagonal NaNbO₃ were characterized by plate‐like morphology with a diameter of 5–15 μm and a thickness of 1–2 μm. The crucial influences on the morphology and crystal phase of the NaNbO₃, such as concentration of [OH^?], surfactant, and K⁺:Na⁺ ratio, were established. By further calcination treatment, the plate‐like hexagonal NaNbO₃ particles could be completely transformed into perovskite structure without morphology change. The XRD and EBSD results indicate that the major face of the calcined particles is parallel to the crystallographic (001)_pc (pseudo cubic index) plane. Compared with the traditional high‐temperature molten salt method, this work provides a simpler way to prepare the template for fabricating textured ceramics.     

Conductive polyaniline/poly(methyl methacrylate) films obtained by electropolymerization

Electrochemical polymerization of aniline, on a Pt foil electrode coated with poly(methyl methacrylate) (PMMA), produces a homogeneous, free-standing, flexible, and conductive polymer film. The conductivity of the films depends on the aniline content and reaches 0.1–0.2 S/cm for films having aniline content of 15% or more. The optimum thickness of precoated PMMA to obtain durable conducting films was found to be in the range of 10–15 μm. Cyclic voltammetric investigation revealed that aniline exhibits a similar electrochemical behavior on a PMMA coated platinum electrode similar to a bare Pt surface. The film gives a fast and reproducible response against ammonia gas within a concentration range of 1.0–0.01%. Scanning electron micrographs indicate that the films have a rough structure consisting of globular regions. © 1996 John Wiley & Sons, Inc.     

Preparation of nanocoatings in the presence of precipitated CaCO3 fillers by UV-curing

Various methods were employed to prepare precipitated calcium carbonate (PCC) particles. Particle size and morphology were dependent on reaction conditions as well as temperature, reagents and stirring, either mechanical or by ultrasound probe sonication. Sonication helped to reduce the size of CaCO₃ particles as well as the precipitation time. Sonication was also used to disperse PCC particles in the UV-curable formulations as well as for preparation of the PCC. Formulations containing precipitated calcium carbonates and ground calcium carbonates in various grades were cured by a Mini UV-Cure device. Mechanical and thermal properties of films were characterized with a Dynamic Mechanical Analyzer (DMA). SEM analysis was also used to determine the shape and the size of the PCCs. Sonication decreased the precipitation time of calcium carbonate at least four times more than that of conventional precipitation procedures and the dispersion of particles in the formulations increased to a great extent.