Design of Polarization- and Incident Angle-Independent Perfect Metamaterial Absorber with Interference Theory

A perfect metamaterial absorber is realized and its properties are theoretically, numerically and experimentally investigated at microwave frequencies. In addition, polarization and incident angle independencies are also tested for the structure. Theoretical, numerical and experimental results show that the proposed model has many advantages compared to those in the literature, such as perfect absorption, polarization and incident angle independencies, very simple design, and operation over a sufficiently wide band. A simple configuration is chosen for the proposed model so that it can be easily tuned for other frequency regimes to realize new absorbers for applications such as sensors and stealth technology.     

A novel floating lossy inductance realization topology with NICs using current conveyors

A negative-impedance converter (NIC) is a useful component in the circuit synthesis theory especially for active RC filter design. In this brief, usefulness of the NIC is shown in a floating inductance realization topology that is an alternative application area for the component. A new floating parallel RL realization topology employing two NICs and three passive components is presented.     

Reply to comment on 'Active simulation of grounded inductors with CCII+ s and grounded passive elements'

A reply to comments made by Abuelma'atti (2000, International Journal of Electronics, 87, 177–181) regarding ‘Active simulation of grounded inductors with CCII+ s and grounded passive elements’ (1998, International Journal of Electronics, 85, 455–462).     

Quantum confinement between self-organized Pt nanowires on Ge(001)

The existence of one-dimensional (1D) electronic states between self-organized Pt nanowires spaced 1.6 or 2.4 nm apart on a Ge(001) surface is revealed by low-temperature scanning tunneling microscopy. These perfectly straight Pt nanowires act as barriers for a surface state (located just below the Fermi level) of the underlying terrace. The energy positions of the 1D electronic states are in good agreement with the energy levels of a quantum particle in a well. Spatial maps of the differential conductivity of the 1D electronic states conclusively reveal that these states are exclusively present in the troughs between the Pt nanowires.     

Single DDCC Biquads with High Input Impedance and Minimum Number of Passive Elements

Two new configurations for the design of biquad filters with high input impedance are presented. The first configuration can synthesize low-pass and high-pass filter functions according to the passive components used. The second one can synthesize a band-pass filter function. The proposed configurations employ only one differential difference current conveyor (DDCC) as active elements and minimum number of passive elements, namely two resistors and two capacitors. Another filter topology based on DDCC is presented that allows modifying the quality factor without changing its natural frequency. All the filters enjoy low sensitivities. SPICE simulation results are given to confirm the validity of the analysis and to point out the high performance of the filters.Muhammed A. Ibrahim was born in Erbil, Iraq in 1969. He obtained his B.Sc. and M.Sc. degrees from Salahaddin University, Erbil, Iraq and Istanbul Technical University, Istanbul, Turkey in 1990 and 1999, respectively, all in electronics and communication engineering. Between 1992 and 1996 he worked as Research Assistant at Salahaddin University where he was later appointed as Assistant Lecturer in 1999. Since 2000 he has been studying for his Ph.D. degree in Electronics and Communication Engineering Program at Istanbul Technical University. His main research interests are CMOS circuit design, current-mode circuits and analog signal processing applications. He has more than 20 international journal and conference papers in scientific review.H. Hakan Kuntman received his B.Sc., M.Sc. and Ph.D. degrees from Istanbul Technical University in 1974, 1977 and 1982, respectively. In 1974 he joined the Electronics and Communication Engineering Department of Istanbul Technical University. Since 1993 he is a professor of electronics in the same department. His research interest include design of electronic circuits, modeling of electron devices and electronic systems, active filters, design of analog IC topologies. Dr. Kuntman has authored many publications on modelling and simulation of electron devices and electronic circuits for computer-aided design, analog VLSI design and active circuit design. He is the author or the coauthor of 76 journal papers published or accepted for publishing in international journals, 91 conference papers presented or accepted for presentation in international conferences, 99 turkish conference papers presented in national conferences and 10 books related to the above mentioned areas. Furthermore he advised and completed the work of 7 Ph.D. students and 31 M.Sc. students. Currently, he acts as the head of the Electronics and Communication Engineering Department in Istanbul Technical University. Dr. Kuntman is a member of the Chamber of Turkish Electrical Engineers (EMO).Oguzhan Cicekoglu 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. He served also as part time lecturer at various institutions. He was with the Biomedical Engineering Institute of the Bogazici University between 1999 and 2001. He is currently Associate Professor at the Electrical and Electronics Engineering Department of the same University.His current research interests include analog circuits, active filters, analog signal processing applications and current-mode circuits. Oguzhan Cicekoglu is the author or co-author of 62 journal papers and about 90 international or local conference papers published or accepted for publishing in journals or conference proceedings.He served as the committee member in various scientific conferences and as reviewer in numerous journals including Analog Integrated Circuits and Signal Processing, IEEE CAS-I, IEEE CAS-II, International Journal of Electronics, Microelectronics Journal, Solid State Electronics and IEE Proceedings Pt.G.Oguzhan Cicekoglu is a member of the IEEE.     

Effect of surface modification of colloidal silica nanoparticles on the rigid amorphous fraction and mechanical properties of amorphous polyurethane–urea–silica nanocomposites

Colloidal silica nanoparticles (NPs) modified with eight different silane coupling agents were incorporated into an amorphous poly(tetramethylene oxide)‐based polyurethane–urea copolymer matrix at a concentration of 10 wt % (4.4 vol %) in order to investigate the effect of their surface chemistry on the structure–property behavior of the resulting nanocomposites. The rigid amorphous fraction (RAF) of the nanocomposite matrix as determined by differential scanning calorimetry and dynamic mechanical analysis was confirmed to vary significantly with the surface chemistry of the NPs and to be strongly correlated with the bulk mechanical properties in simple tension. Hence, nanocomposites with an RAF of about 30 wt % showed a 120% increase in Young's modulus, a 25% increase in tensile strength, a 15% decrease in elongation at break with respect to the neat matrix, which had no detectable RAF, whereas nanocomposites with an RAF of less than 5% showed a 60% increase in Young's modulus, a 10% increase in tensile strength and a 5% decrease in the elongation at break. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 2543–2556     

Optimal Breast Biopsy Decision-Making Based on Mammographic Features and Demographic Factors

Breast cancer is the most common non-skin cancer affecting women in the United States, where every year more than 20 million mammograms are performed. Breast biopsy is commonly performed on the suspicious findings on mammograms to confirm the presence of cancer. Currently, 700,000 biopsies are performed annually in the U.S.; 55%-85% of these biopsies ultimately are found to be benign breast lesions, resulting in unnecessary treatments, patient anxiety, and expenditures. This paper addresses the decision problem faced by radiologists: When should a woman be sent for biopsy based on her mammographic features and demographic factors? This problem is formulated as a finite-horizon discrete-time Markov decision process. The optimal policy of our model shows that the decision to biopsy should take the age of patient into account; particularly, an older patient's risk threshold for biopsy should be higher than that of a younger patient. When applied to the clinical data, our model outperforms radiologists in the biopsy decision-making problem. This study also derives structural properties of the model, including sufficiency conditions that ensure the existence of a control-limit type policy and nondecreasing control-limits with age.     

High-output-impedance transadmittance type continuous-time multifunction filter with minimum active elements

A new transadmittance multifunction filter with single input and three outputs employing only three positive-type second-generation current conveyors and five passive elements is presented. The proposed filter realizes three basic filter functions simultaneously, all at high impedance outputs. No component matching is required and all the passive sensitivities are low. Experimental verification is also performed.