A new differential configuration suitable for realization of high CMRR, all-pass/notch filters

In this paper, a new configuration suitable for realization of differential input-differential output first order, second order all-pass and notch filters with high CMRR is given. The proposed configuration uses two negative type second-generation current conveyors (CCII-), and three admittances. Two first order and one second order all-pass filters and a notch filter (tunable if current controlled conveyor CCCII is used) are extracted from the proposed configuration. Tracking error, element mismatch, sensitivity analysis, simulation and experimental results are included.     

Deadbeat control of discrete-time systems with singular state matrix using canonical decomposition

The problem of deadbeat control of controllable discrete-time systems with singular state matrix is considered. Our approach is based on the representation of the system obtained by isolating the reachable part of the system and the controllable but unreachable part using the Kalman structure theorem. It is shown that, eigenvalue assignment for controllable but unreachable single-input systems does not lead to a unique control law. In fact, the extra degrees of freedom available can be used to shape the transient response characteristics of the system.     

Laminar viscous flow fields in moving curved channels

The laminar steady flow of air through moving narrow deep circumferential grooves on a rotor is studied. Fluid enters the moving grooves from a stationary inlet nozzle with uniform velocity and exits into a stationary diffuser after approximately 150 degrees of rotation. Three dimensional developing velocity profiles and pressure distributions are presented for a variety of operating conditions. Computed overall head-flow characteristics are found to be in relatively close agreement with a simple Poiseuille model where both walls are taken to be moving at the same rate and in the same direction at a velocity different from the entrance velocity.     

Itinerant Delivery of Popular Data via WIDE Hot Spots

Wireless Information Delivery Environment (WIDE) is a distributed data dissemination system, which uses IEEE 802.11b technology. WIDE aims to deliver popular information services to registered mobile clients in WLAN hot spots. Data delivery is based on broadcasting and multicasting to provide scalability and efficient use of the wireless channel. Reliability is assured with a combination of Forward Error Correction (FEC), data carousel, and ARQ techniques. This paper presents the proposed system architecture with the details of reliable and secure data dissemination mechanisms. Functional evaluation of the proposed system and mechanisms on the implemented prototype are also included in this paper. This work is partially supported by the State Planning Organization of Turkey under the grant number 98K120890, and by the Bogazici University Research Projects under the grant number 02A105D. A shorter version of this paper was presented in WONS 2004 in Madonna di Campiglio, Italy. Sinan Isik received the B.S. degree in mathematics, and the M.S. degree in computer engineering from Bogazici University, Istanbul, Turkey in 1999 and 2003, respectively. He is currently working toward for the PhD degree in computer engineering in the same university. His research interests include wireless communication, wireless ad-hoc networks and wireless sensor networks. Mehmet Yunus Donmez received his B.S. degree from Mathematics Department in 1999 and his MS degree from the Computer Engineering Department of Bogazici University, Istanbul, Turkey in 2003. He is currently studying for his PhD degree in computer engineering. His research interests are wireless networks and content delivery systems, along with QoS, multicasting and fairness issues in MANETs. Cem Ersoy received his BS and MS degrees in electrical engineering from Bogazici University, Istanbul, in 1984 and 1986, respectively. He worked as an R&D engineer in NETAS A.S. between 1984 and 1986. He received his PhD in electrical engineering from Polytechnic University, Brooklyn, New York in 1992. Currently, he is a professor and department head in the Computer Engineering Department of Bogazici University. His research interests include performance evaluation and topological design of communication networks, wireless communications and mobile applications. Dr. Ersoy is a Senior Member of IEEE.     

The influence of gallium on the magnetocaloric properties of Gd5Si2Ge2

Gd₅Si₂Ge₂ was alloyed with varying amounts of Ga to study its influence on the giant magnetocaloric effect. Investigations on Gd₅(Si_2−xGe_2−x)Ga_2x with 2x = 0.03, 0.05 and 0.13 were carried out using X-ray powder diffraction, temperature and magnetic field dependent magnetization measurements, and differential scanning calorimetry. We observe that as the Ga content increases, the temperature stability range of the monoclinic phase narrows, and the orthorhombic structure gains stability. This is expected to be related to the decrease in the (Si/Ge)(Si/Ge) bond distance in the monoclinic phase. The maximum entropy change for the parent compound at 270 K was found to be 9.8 J kg⁻¹ K⁻¹ in an applied field of 5 T. For 2x = 0.03, this value reduces to 8.5 J kg⁻¹ K⁻¹, and the temperature corresponding to the maximum entropy change shifts marginally to 278 K. For other 2x values, the maximum entropy change further decreases.     

Thermodynamic analysis of a building using exergy analysis method

This study deals with exergetic assessment of an educational building heated by a conventional boiler in a heating center. The heating system is examined from the generation stage to the envelope of the building. In general the heat loss calculations are made using both energy and exergy analysis methods. The energy and exergy flows between the stages are obtained using a pre-design tool for an optimized building design. Energy and exergy losses are obtained to evaluate the performance of the system. A conventional boiler in the heating center and a fan coil unit in a room are considered in the analysis. Total exergy input rate is calculated to be 694.5 kW, while the largest exergy loss rate is obtained to be 333 kW. Exergetic efficiencies of the conventional boiler and the fan coil unit are also found to be 13.4% and 37.6%, respectively.     

Quick-boiling noodle production by using infrared drying

In this study, infrared treatment at different powers was used at drying stage of noodle production. Drying time was reduced to 3 min 30 s and 50% reduction in cooking time was obtained at the highest power. Lower cooking loss and total organic matter values, higher maximum force values were obtained for noodles dried by using infrared, indicating improved quality. Infrared treatment generally caused an increase in Rapid ViscoAnalyzer viscosity values of the noodles. Starch granules of the noodles dried by using infrared retained their birefringence to a large extent and increase in intensity of some peaks and formation of a new peak at 2θ = 20° (V-type diffraction pattern) were observed in X-ray diffraction patterns. Relative intensities of some protein bands in SDS-PAGE patterns decreased, total dietary fiber and enzyme resistant starch contents increased slightly. Starch digestibility (in vitro) values increased gradually as the infrared power applied increased.