Biodiesel production from pomace oil and improvement of its properties with synthetic manganese additive

Renewable energy sources are attracting more attention due to lower cost and lower pollution relative to fossil fuels. The aim of this experimental work is the production of renewable and clean methyl ester from pomace oil as an alternative fuel. This oil was obtained from pomace which is the waste of olive oil plants. Optimum producing conditions were determined experimentally. The maximum yield was obtained at 30% of methanol/oil ratio, 60 °C temperature for 60 min with NaOH catalyst. The properties of the biodiesel thus obtained were compared with diesel fuel requirements. An organic based Manganese additive improved the biodiesel properties. Doping the fuel at a ratio of 12 μmol/l oil methyl ester led to a 20.37% decrease in viscosity, 7 °C fall in the flash point and reduced the pour point from 0 °C to −15 °C. This blend of pomace oil methyl ester-diesel fuel with manganese additive was tested in a direct injection diesel engine. The maximum effect of the new fuel blend and diesel fuel on engine performance was obtained at 1400 rpm.     

Channel Estimation by Using Short Training Sequences in CDMA Systems

Multiuser detection techniques are known to be effective to counter the presence of multiuser interference in code division multiple access channels. Multiuser detectors can provide excellent performance only when the channel impulse responses of all the users are precisely known. Hence, channel estimation becomes a challenging issue in mobile communication systems. In this paper, we address the problem of efficient maximum likelihood mobile radio channel estimation at high channel efficiency that requires a short training sequence along with the known spreading sequence. The proposed system can be employed in both the uplink and downlink of a heavily loaded multiuser CDMA system. The extension of the approach with unknown users' delays are also proposed. We present results that show the success of this method in recovering the transmitted bits with a relatively small number of preamble bits. Ahmet Rizaner was born in Larnaca, Cyprus, on January 31, 1974. He received the B.S. and M.S. degrees in Electrical and Electronics Engineering from the Eastern Mediterranean University, Famagusta, North Cyprus, in 1996 and 1998, respectively. He completed his PhD. degree in Electrical and Electronic Engineering in Eastern Mediterranean University and joined Eastern Mediterranean University as a lecturer in 2004. He is lecturing in the School of Computing and Technology. His main research interests include CDMA communications, adaptive channel estimation, and multiuser detection techniques. Hasan Amca was born in 1961 in Nicosia-Cyprus. He graduated from the Higher Technological Institute in Magosa-Cyprus (which is renamed later as Eastern Mediterranean University). He joined EMU in 1985 after receiving a M.Sc. (Digital Signal Processing) degree from the University of Essex in England (1985). He took his Ph.D. (Mobile Communications) from the University of Bradford where he was on a Commonwealth scholarship. He has been teaching in the Electrical and Electronic Engineering Department of Eastern Mediterranean University since 1993 where he also served as the vice chairman from Spring 1998 to Spring 2000. He has been appointed as the Director of the School of Computing and Technology of the EMU since Spring 2000. His research interests include Multi User Detection of CDMA signals, Adaptive Equalisation, Multi Carrier Systems, Mobile Radio Systems and Networks, Internet and Information Technology Applications in Education. Kadri Hacıoğlu was born in Nicosia, Cyprus. He received the B.Sc., M.Sc., and Ph.D. degrees in electrical and electronic engineering from the Middle East Technical University, Ankara, Turkey, in 1980, 1984, and 1990, respectively. After his two-year military service, in 1992, he joined the faculty of Eastern Mediterranean University, Magosa, North Cyprus, as an Assistant Professor, and became an Associate Professor in 1997. While there, he taught several classes on electronics, digital communications, speech processing and neural networks. During this time, he conducted research on applying fuzzy logic, neural networks, and genetic algorithms to signal processing and communications problems. From 1998 to 2000, he was a Visiting Professor in the Department of Computer Science, University of Colorado, Boulder. Here, he taught classes on neural networks and continued his research. Since 2000, he has been a Research Associate at the Center for Spoken Language Research, University of Colorado. He has authored or coauthored numerous papers and supervised a dozen M.Sc./Ph.D. theses. His current research interests are concept-based language modeling, speech understanding, natural language generation, and search methods in speech recognition/understanding. He also does research on multiuser detection and equalization in CDMA systems. Ali Hakan Ulusoy was born in Eskişehir, Turkey, on June 3, 1974. He graduated from the double major program of the department of Electrical and Electronic Engineering and department of Physics in Eastern Mediterranean University as the first rank student of Faculty of Engineering in 1996. He received his M.S. degree in Electrical and Electronic Engineering in Eastern Mediterranean University in 1998. He completed his PhD. degree in Electrical and Electronic Engineering in Eastern Mediterranean University and joined Eastern Mediterranean University as a lecturer in 2004. He is lecturing in the School of Computing and Technology. His current research interests include receiver design, multi-user detection techniques, blind and trained channel estimation in Code Division Multiple Access (CDMA).     

Parallel WaveCluster: A linear scaling parallel clustering algorithm implementation with application to very large datasets

A linear scaling parallel clustering algorithm implementation and its application to very large datasets for cluster analysis is reported. WaveCluster is a novel clustering approach based on wavelet transforms. Despite this approach has an ability to detect clusters of arbitrary shapes in an efficient way, it requires considerable amount of time to collect results for large sizes of multi-dimensional datasets. We propose the parallel implementation of the WaveCluster algorithm based on the message passing model for a distributed-memory multiprocessor system. In the proposed method, communication among processors and memory requirements are kept at minimum to achieve high efficiency. We have conducted the experiments on a dense dataset and a sparse dataset to measure the algorithm behavior appropriately. Our results obtained from performed experiments demonstrate that developed parallel WaveCluster algorithm exposes high speedup and scales linearly with the increasing number of processors.     

Neural network based instant parameter prediction for wireless sensor network optimization models

Wireless Networks - Optimal operation configuration of a Wireless Sensor Network (WSN) can be determined by utilizing exact mathematical programming techniques such as Mixed Integer Programming...     

Robust stabilization of spacecraft attitude motion under magnetic control through time‐varying integral sliding mode

Magnetic spacecraft attitude control is suitable for missions with moderate pointing and stabilization requirements. It would be especially preferable if an implemented three‐axis magnetic control law guarantees global and moreover robust stabilization. Motivated by this consideration, in this work, the integral sliding mode control method is successfully applied to the purely magnetic attitude control problem for the first time in literature. The resulting magnetic integral sliding mode control system, which is designed via Lyapunov's direct method by taking the four major environmental disturbance torques and the full inertia matrix uncertainty into account, has the expected insensitivity against environmental disturbances in the plane of continuous actuation. Along the instantaneous direction of underactuation, which continuously varies in control space as the satellite moves along the orbit, there is no counteraction to perturbations. However, as seen in the results of the high‐fidelity simulation, state trajectories are ultimately bounded in the vicinity of the reference state independently from the initial state thanks to the proven robustness of the global stability. Performance robustness of the obtained control system against disturbances and model uncertainty is evaluated to be superior through a couple of comparisons with existing control laws even though it is partial due to the intrinsic underactuation in the system.     

Dwell time-based stabilisation of switched delay systems using free-weighting matrices

In this paper, we present a quasi-convex optimisation method to minimise an upper bound of the dwell time for stability of switched delay systems. Piecewise Lyapunov–Krasovskii functionals are introduced and the upper bound for the derivative of Lyapunov functionals is estimated by free-weighting matrices method to investigate non-switching stability of each candidate subsystems. Then, a sufficient condition for the dwell time is derived to guarantee the asymptotic stability of the switched delay system. Once these conditions are represented by a set of linear matrix inequalities , dwell time optimisation problem can be formulated as a standard quasi-convex optimisation problem. Numerical examples are given to illustrate the improvements over previously obtained dwell time bounds. Using the results obtained in the stability case, we present a nonlinear minimisation algorithm to synthesise the dwell time minimiser controllers. The algorithm solves the problem with successive linearisation of nonlinear conditions.     

Air oxidation of aqueous cyanides in a countercurrent fixed bed reactor

This study was conducted to discuss the removal of cyanides from water by air oxidation. Experiments were carried out in a countercurrent fixed bed reactor for three different values of temperature, concentration, gas and liquid flow rates. It was operated at pH 12 by using delrin (formaldehyde polymer) as packing material. Effects of some operating parameters on the conversion were studied, and it was observed that the conversion percent increased by increasing temperature and decreasing gas and liquid flow rates. Effect of concentration was not steady. A conversion of 89% was achieved under optimum conditions while it ranges from 44 to 79% at room temperature.