The use of personal protection equipment does not negatively affect paramedics’ attention and dexterity: a prospective triple-cross over randomized controlled non-inferiority trial

Background The COVID-19 pandemic led to widespread use of personal protection equipment (PPE), including filtering face piece (FFP) masks, throughout the world. PPE. Previous studies indicate that PPE impairs neurocognitive performance in healthcare workers. Concerns for personnel safety have led to special recommendations regarding basic life support (BLS) in patients with a potential SARS-CoV-2 infection, including the use of PPE. Established instruments are available to assess attention and dexterity in BLS settings, respectively. We aimed to evaluate the influence of PPE with different types of FFP masks on these two neuropsychological components of EMS personnel during BLS. Methods This was a randomized controlled non-inferiority triple-crossover study. Teams of paramedics completed three 12-min long BLS scenarios on a manikin after having climbed three flights of stairs with equipment, each in three experimental conditions: (a) without pandemic PPE, (b) with PPE including a FFP2 mask with an expiration valve and (c) with PPE including an FFP2 mask without an expiration valve. The teams and intervention sequences were randomized. We measured the shift in concentration performance using the d2 test and dexterity using the nine-hole peg test (NHPT). We compared results between the three conditions. For the primary outcome, the non-inferiority margin was set at 20 points. Results Forty-eight paramedics participated. Concentration performance was significantly better after each scenario, with no differences noted between groups: d2 shift control versus with valve − 8.3 (95% CI − 19.4 to 2.7) points; control versus without valve − 8.5 (− 19.7 to 2.7) points; with valve versus without valve 0.1 (− 11.1 to 11.3) points. Similar results were found for the NHPT: + 0.3 (− 0.7 to 1.4), − 0.4 (− 1.4 to 0.7), 0.7 (− 0.4 to 1.8) s respectively. Conclusion Attention increases when performing BLS. Attention and dexterity are not inferior when wearing PPE, including FFP2 masks. PPE should be used on a low-threshold basis.

Dual-Side Phase-Shift Control for Strongly Coupled Series–Series Compensated Electric Vehicle Wireless Charging Systems

Wireless power transfer (WPT) for electric vehicles is an emerging technology and a future trend. To increase power density, the coupling coefficient of coils can be designed to be large, forming a strongly coupled WPT system, different from the conventional loosely coupled WPT system. In this way, the power density and efficiency of the WPT system can be improved. This paper investigates the dual-side phase-shift control of the strongly coupled series–series compensated WPT systems. The mathematical models based on the conventional first harmonic approximation and differential equations for the dual-side phase-shift control are built and compared. The dual-side phase-shift angle and its impact on the power transfer direction and soft switching are investigated. It is found that synchronous rectification at strong couplings can lead to hard switching because the dual-side phase shift in this case is over 90°. In comparison, a relatively high efficiency and soft switching can be realized when the dual-side phase shift is below 90°. The experimental results have validated the analysis.

High Efficient Resonant DC-DC Converter for Automotive LED Driver Applications using Phase Shift Control Strategy

A high frequency DC-DC converter operating in the MHz range is proposed, which can achieve unbiased load current even while maintaining high performance over a wide range of load voltages. Due to these functions, the provided transformer is suitable for LED driver applications, which require different types of LEDs to operate with controlled current. The proposed transformer satisfies the uncontrolled load current using the LCL-T resonance community and achieves high efficiency using a predetermined switching frequency. The LCL-T resonance transformer also works effectively in controlling its output to the required rating using phase shift control. The overall performance of the LCL-T Echo transducer was evaluated and compared with the LC3L controlled echo transducer. Simulation work is done using the MATLAB / Simulink program.

Multi-Objective Unified Optimal Control Strategy for DAB Converters with Triple-Phase-Shift Control

To solve the problems of large current stress, difficult soft-switching of all switches, and slow dynamic response of dual active bridge converters, a multi-objective unified optimal control strategy based on triple-phase-shift control was proposed. The forward power flow global modes of triple-phase-shift control were analyzed, and three high-efficiency modes were selected to establish the analytical models of current stress and soft-switching. Combined with these models, the optimal solutions in different modes were derived by using the cost function-optimization equation to overcome the limitation of the Lagrange multiplier method, such that the DAB converter achieved the minimum current stress, and all switches operated in the soft-switching state over the entire power range. At the same time, the virtual power component was introduced in the phase-shift ratio combination, which improved the dynamic response of output voltage under the input voltage or load steps changed by power control. The theoretical analysis and experimental results show that the proposed control strategy can optimize the performance of the DAB converter from three aspects, such as current stress, soft-switching, and dynamic response, which achieves multi-objective optimization of the steady-state and dynamic performance of DAB converters.