Realization of Low-Voltage Modified CBTA and Design of Cascadable Current-Mode All-Pass Filter

In this paper, a low voltage modified current backward transconductance amplifier (MCBTA) and a novel first-order current-mode (CM) all-pass filter are presented. The MCBTA can operate with ±0.9 V supply voltage and the total power consumption of MCBTA is 1.27 mW. The presented all-pass filter employs single MCBTA, a grounded resistor and a grounded capacitor. The circuit possesses low input and high output impedances which make it ideal for current-mode systems. The presented all-pass filter circuit can be made electronically tunable due to the bias current of the MCBTA. Non-ideal study along with simulation results are given for validation purpose. Further, an nth-order cascadable all-pass filter is also presented. It uses n MCBTAs, n grounded resistors and n grounded capacitors. The performance of the proposed circuits is demonstrated by using PSPICE simulations based on the 0.18 µm TSMC level-7 CMOS technology parameters

Current and Voltage Mode Multiphase Sinusoidal Oscillators Using CBTAs

Current-mode (CM) and voltage-mode (VM) multiphase sinusoidal oscillator (MSO) structures using current backward transconductance amplifier (CBTA) are proposed. The proposed oscillators can generate n current or voltage signals (n being even or odd) equally spaced in phase. n+1 CBTAs, n grounded capacitors and a grounded resistor are used for nth-state oscillator. The oscillation frequency can be independently controlled through transconductance (gm) of the CBTAs which are adjustable via their bias currents. The effects caused by the non-ideality of the CBTA on the oscillation frequency and condition have been analyzed. The performance of the proposed circuits is demonstrated on third-stage and fifth-stage MSOs by using PSPICE simulations based on the 0.25 µm TSMC level-7 CMOS technology parameters

Investigating Effects of Testing Parameters on Frictional Heating of UHMWPE by Taguchi Method

Frictional heating makes detrimental effects on surrounding tissue and lubricant around the artificial hip joint. For reduction of this thermal damage, testing parameters and their effects were investigated by using the Taguchi method and analysis of variance. Ultra high molecular weight polyethylene (UHMWPE) acetabular liners and CoCrMo femoral head artificial hip joint components were used as samples. Frictional heating measurements of the joints were carried out on a custom made hip joint friction experimental setup. Surface dimples in different sizes were machined on the inner surface of acetabular insert samples. The tests were conducted under different loading conditions with different testing time. Bovine calf serum was used as lubricant with different amount of third body wear particles in it. Temperature rise in acetabular and femoral component was recorded with embedded thermocouples. The experimental results demonstrated that the surface dimples were the major parameter on frictional heating, followed by applied load, amount of third body particles and time. The optimal combination of the testing parameters was predicted and validated by doing experiments

satisfaction and complaints

This study examines prevailing characteristics of public attitudes to local government in Turkey based on the findings of a questionnaire based research project. The level of public knowledge of local government, people's satisfaction with local service provision, public views and complaints about local services are analysed. The findings show that the level of public knowledge of local government is low and people do not complain about local government services although the level of satisfaction is low. The belief that complaints would have no effect is the main reason for not complaining. The impact of sex, age, education, income, length of residence in the locality, housing tenure, and political opinion on public attitudes to local government is also assessed. Of these variables, age, education and income levels are found to be significant

Surface Texturing of Vitamin E Blended UHMWPE for Reduction of Wear

Ultra high molecular weight polyethylene (UHMWPE) has been the most commonly used bearing material in artificial hip and knee replacements. But wear and wear debris of UHMWPE has been the most important problem which cause aseptic loosening and revision surgery of these replacements. For enhangement of wear resistance, new generation UHMWPE materials have been developed and different surface modification techniques have been tried. The objective of this study is to determine the effect of surface dimples on wear behavior of conventional UHMWPE and vitamin E blended UHMWPE (VE-UHMWPE) in ultra-pure water lubrication conditions. Pin-on-disc tribotester was used for measurement of friction coefficient and wear. 0.5 mm in diameter dimples were machined on the surfaces of UHMWPE and VE-UHMWPE discs. CoCrMo pins were used as counter surface. Results were evaluated in terms of materials and presence of dimples

Measurement of Wear in Orthopedic Prosthesis

Wear in orthopedic prosthesis has been the main limiting factor of total joint replacement's service life. Wear analysis of total joint replacements is essential for determining failure mechanism, prediction of wear and longevity of implants. So it would be possible to improve design, material and manufacturing quality and service life of these devices. Radiographic, gravimetric, volumetric and optical techniques are current methods for measuring of wear in retrieved implants. Gravimetric method is the standardized method for quantifying wear volumes of total joint prosthesis. Although this method is effective for determining experimental wear volume in simulated conditions, it is not suitable for assessing the clinically retrieved prosthesis for which there is no pre-wear data available. Each of the wear measuring methods has advantages and limitations. Researches have been going on for developing effective methods. In this paper the techniques that are currently used for evaluating wear of orthopedic prosthesis like gravimetry, coordinate measuring machine, micro computed tomography, and digital photogrammetry are explained. The literature works and new trends in metrological assessment of wear are reviewed