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Aim: Age estimation is an important aspect of forensic odontology. Calculation of pulp volume using CBCT and its correlation with age could be an effective, non destructive method. The aim of this pilot study was to verify and calibrate the proposed method of calculating pulp and tooth volume using CBCT. Materials and Method: The study was conducted on six extracted monoradicular teeth which were scanned by Cone Beam CT (CS9300-C 3D.Carestream Health, Inc. Rochester, NY) after endodontic preparation. The tooth (TV2) and pulp volumes (PV 2) were then calculated using imaging software (Xelis Dental software (INFINITT Inc., Seoul, South Korea). Then actual tooth (TV1) and pulp volumes (PV1) were calculated based on the Archimedes principle. The pulp and tooth volume ratios R1 and R2 were also calculated. The estimated and actual values were compared and percentage error was calculated. Results: The percentage error was also calculated to evaluate the accuracy which was found to be 8.84%, 2.6% and 12.7% for TV1 and TV2, PV1 and PV2 and R1 and R2 respectively. Conclusion: These were in accordance with the results by Yang et al.7 who obtained a percentage error of ±7.8% while the estimated error was quite less than that reported by Star et al8 who reported the maximum percentage error to be 21% and 16% for pulp and tooth volumes respectively. [ABSTRACT FROM AUTHOR]

This paper aims to focus on the smooth output of DC-DC buck converters in wireless power transfer systems under input perturbations and load disturbances using the high-order sliding mode controller (HOSM) and HOSM with super-twisting differentiator (HOSM + STD). The proposed control approach needs only measurement of converter output voltage. Theoretical analysis and design procedures, as well as the super-twisting differentiator of the proposed controller are presented in detail with the prescribed convergence law of high-order sliding modes. Comparisons of both simulation and experimental results among conventional proportional-integral (PI) control, traditional sliding mode control (SMC), HOSM and HOSM + STD under various test conditions such as steady state, input voltage perturbations and output load disturbances, are presented and discussed. The results demonstrate and validate the effectiveness and robustness of the proposed control method. [ABSTRACT FROM AUTHOR]

This paper proposes a current-fed non-isolated soft-switching bidirectional dc/dc converter for interfacing energy storage to dc microgrid. The proposed converter employs a current-fed half-bridge boost converter at front-end followed by an LCL resonant circuit to aid in soft-switching of semiconductor devices. A voltage doubler at output is selected to enhance the gain by $2 \times $. The LCL resonant circuit also adds a suitable voltage gain. Therefore, the topology offers overall high voltage gain without transformer or large number of multiplier circuits. For buck operation, high side voltage is first divided by half with capacitor divider to gain higher stepdown ratio. Converter operates at high switching frequency to realize merits of reduced magnetics and filters. Zero voltage turn-on is achieved for all switches and zero current turn-on and turn-off is achieved for all diodes for both buck/boost operation. Voltage across switches and diode is clamped naturally without any external snubber circuit. Detailed analysis and design have been proposed. A proof-of-concept experimental prototype rated at 350 W has been designed, developed, and tested in the laboratory to demonstrate the performance and validate the claims of the converter for wide load variation. [ABSTRACT FROM AUTHOR]

A current-fed three-phase push–pull bidirectional dc–dc converter is proposed with unique features of natural zero current commutation and natural device voltage clamping. The proposed topology is suitable for uninterruptible power supply, storage, renewable energy sources, and interfacing two dc buses of 48- and 380-V dc buses in a dc microgrid. The proposed converter implements a novel and innovative modulation that results in natural commutation with zero current switching (ZCS) and device voltage clamping of low voltage side (LVS) current-fed devices, and zero voltage switching (ZVS) turn-on of high voltage side (HVS) voltage-fed devices. It eliminates the use of passive/active clamp circuits to mitigate the turnoff voltage spike across the devices, a traditional problem associated with current-fed topologies. Additionally, the higher ripple frequency reduces the volume of the transformer and the input inductor, making it suitable for high-power applications. The detailed modulation scheme, steady-state operation, and analysis, design, and soft-switching conditions have been explained. Simulation results obtained using PSIM 9.3 have been illustrated to verify the modulation, analysis, and proposed design. Experimental results have been demonstrated for full load (1 kW), half-load (500 W), and 20% load conditions on a proof-of-concept hardware prototype to validate the claims and performance. The efficiency is plotted against various load conditions for a wide range of battery voltage variation (40–59 V). Peak efficiencies of 95.8% and 93.8% are obtained at half-load condition for an input voltage of 59 V and nominal voltage (48 V), respectively. The experimental results for battery charging (reverse direction) using dual phase-shift plus pulsewidth modulation are given. The ZVS of HVS switches and the synchronous rectification of LVS active switches are shown through experimental results. [ABSTRACT FROM AUTHOR]

An impulse-commutated current-fed three-phase dc/dc converter is proposed. It is a three-inductor current divider topology that reduces the current stress of the components. The proposed converter attains zero current switching (ZCS) of the semiconductor devices via impulse commutation utilizing the circuit paracitics. The devices' voltage is clamped at Vo/n. Voltage clamping and zero-current commutation of devices are load independent. Load voltage is regulated by employing variable-frequency modulation. The current-fed topology with inherent boost ability simplifies the transformer design by reducing the required turns ratio. Rectifier diodes also commutate with ZCS without ringing and eliminate the need for a secondary snubber. A comprehensive study of the proposed converter together with the experimental results obtained from a laboratory prototype of 1 kW have been presented to validate the claims and to evaluate the converter's performance. The proposed converter is suitable for low-voltage high-current applications requiring high voltage gain. It inherently offers short-circuit protection. [ABSTRACT FROM AUTHOR]