Combined finite element and peridynamic analyses for predicting failure in a stiffened composite curved panel with a central slot

This study presents an analysis approach based on a merger of the finite element method and the peridynamic theory. Its validity is established through qualitative and quantitative comparisons against the test results for a stiffened composite curved panel with a central slot under combined internal pressure and axial tension. The predicted initial and final failure loads, as well as the final failure modes, are in close agreement with the experimental observations. This approach demonstrates the capability of the PD approach to assess the durability of complex composite structures.     

New highly linear tunable transconductor circuits with low number of MOS transistors

In this article, two new highly linear tunable transconductor circuits are proposed. The transconductors employ only six MOS transistors operated in saturation region. The second transconductor is derived from the first one with a slight modification. Transconductance of both transconductors can be tuned by a control voltage. Both of the transconductors do not need any additional bias voltages and currents. Another important feature of the transconductors is their high input and output impedances for cascadability with other circuits. Besides, total harmonic distortions are less than 1.5% for both transconductors. A positive lossless grounded inductor simulator with a grounded capacitor is given as an application example of the transconductors. Simulation and experimental test results are included to show effectiveness of the proposed circuits.     

Realization of arbitrary current transfer functions based on commercially available CCII + s

In this paper, a new topology for realizing arbitrary n^th‐order current transfer function (TF), consisting of only plus‐type second‐generation current conveyors (CCII+s), is suggested. The proposed TF simulator employs only grounded capacitors and is free from the passive element matching requirements. The developed TF simulator can be constructed directly with commercially available active components such as AD844s. It has low‐input and high‐output impedances, a feature which makes it fully cascadable with other current‐mode topologies. Moreover, the proposed simulator can provide gain at its outputs. Simulation and experimental test results for various filter examples are included to confirm the claimed theory. Copyright © 2012 John Wiley & Sons, Ltd.     

Microencapsulated di-ammonium hydrogen phosphate (DAHP) with a polyurethane shell: characterization and its properties in wood

European Journal of Wood and Wood Products - This work deals with the microencapsulation of di-ammonium hydrogen phosphate (DAHP) in polyurethane using an interfacial polymerization method. The...     

Performance of a sulfide-oxidizing, sulfur-producing membrane biofilm reactor treating sulfide-containing bioreactor effluent

Sulfide-containing waste streams are generated in mining, petrochemical plants, tanneries, viscose rayon manufacture, and the gasification of coal. Colorless sulfur bacteria can oxidize sulfide to elemental sulfur (S°), which can be recovered, when oxygen is their electron acceptor. This study evaluated sulfide oxidation and S° recovery in an oxygen-based membrane biofilm reactor (MBfR) treating the effluent from a sulfidogenic anaerobic baffled reactor. Sulfide oxidation efficiency (37-99%) and S° recovery (64-89% of oxidized sulfide) could be controlled by manipulating the sulfide loading, oxygen pressure to the fibers, and hydraulic retention time (HRT). For example, too-low oxygen pressure decreased S° recovery due to decreased sulfide oxidation, but too-high oxygen pressure lowered S° recovery due to its oxidation to sulfate. Most importantly, high sulfide oxidation (>98%) and conversion to S° (>75%) could be achieved together when the sulfide loading was less than 1.7 mol/m2·d and the O? pressure was sufficient to give an O? flux of at least 1.5 mol/m2·d. However, higher sulfide loading could be compensated by a higher O? pressure, and the best performance occurred when the sulfide loading was high (2 molS/m2·d), the O? pressure was high (～1 atm), and the HRT was short (1.9 h). Membrane fouling caused a low O? flux, which led to low sulfide-oxidation efficiency, but fouling could be reversed by mild acid washing.     

Nuclear power in open energy markets: A case study of Turkey

For many decades, like many developed countries, Turkey has controlled her electricity sector as a state-owned monopoly. However, faced with rapid electricity demand growth, Turkey started to consider nuclear option. The present paper aims at evaluating both the present status of nuclear power in general and its implications for Turkish energy market in particular. After examining existing nuclear power technology and providing a brief overview of nuclear power economics; it focuses on the repercussions of nuclear power for Turkish energy market. The paper concludes that, in the short run, it may be considered to keep nuclear power within Turkish energy mix because it is an important carbon-free source of power that can potentially make a significant contribution to both Turkey's future electricity supply and efforts to strengthen Turkey's security of supply. However, in the long term, nuclear power should be retained in Turkey only if it has a lower cost than competing technologies.     

On the realization of high-order current-mode filter employing current controlled conveyors

In this paper, a general structure for realizing high-order current-mode analog filter responses with single-input and three-outputs is presented. The proposed circuit uses dual-output second-generation current controlled conveyors (DO-CCCIIs) and only grounded capacitors (Active-C structure), and can simultaneously realize low-pass, band-pass (if order is even number) and high-pass filter responses. The developed circuit does not require any component matching constraints thus it is suitable for fully integrated circuit (IC) technology. Simulations are performed for the fourth-order Butterworth filter to illustrate the frequency domain performance of the circuit.     

The Effects of Non-Idealities and Current Limitations on the Simulated Inductances Employing Current Conveyors

Active devices such as current conveyors play an essential role on the performance of simulated inductances. The effects of second-generation current conveyor (CCII) non-idealities on the proposed and on the previously published inductances are investigated, in which lossless inductances are realized. CCIIs like all active devices have terminal current limitations that can not be exceeded. Thus, the values of the applied input current sources for the proposed and previously published inductances depending on the passive elements values and applied signal frequency impose restrictions on the input current of the inductor. Erkan Yuce was born in 1969 in Nigde, Turkey. He received the B.Sc. degree from Middle East Technical University and M.Sc. degree from Pamukkale University in 1994 and 1998 respectively, all in Electrical and Electronics Engineering. He is currently Research Assistant and a Ph.D. student at the Electrical and Electronics Engineering Department of Bogazici University. His current research interests include analog circuits, active filters, synthetic inductors, voltage-mode current-mode circuits. He is the author or co-author of about 4 papers published in scientific journals or conference proceedings Oguzhan Cicekogluwas born in 1963 in Istanbul, Turkey. He received the B.Sc. and M.Sc. degrees from Bogazici University and the Ph.D. degree from Istanbul Technical University all in Electrical and Electronics Engineering in 1985, 1988 and 1996 respectively. He served as lecturer at the School of Advanced Vocational Studies Electronics Prog. of Bogazici University where he held various administrative positions between 1993 and 1999, and as part time lecturer at various institutions. He was with Biomedical Engineering Institute between 1999 and 2001. He is currently Associate Professor at the Electrical and Electronics Engineering Department of Bogazici University. His current research interests include analog circuits, active filters, analog signal processing applications and current-mode circuits. He is the author or co-author of about 150 papers published in scientific journals or conference proceedings. Oguzhan Cicekoglu is a member of the IEEE.