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Exploring the genomic traits of infant-associated microbiota members from a Zimbabwean cohort
No full textIsolated Modular Multilevel Matrix Converter (I-M3C) Based Novel Solid-State Transformer (SST) With Low-Frequency Medium-Voltage AC Port
No full textThis article proposes a novel solid-state transformer (SST) having a low-frequency medium-voltage ac (LF-MVac) port distinctively, which can be the key equipment for smart distribution networks based on LF-MVac interconnection. The proposed SST has four ports of power-frequency medium-voltage ac (MVac), LF-MVac, low-voltage dc (LVdc), and low-voltage ac (LVac). In addition to the two-level low-voltage dc/ac converter, the proposed SST is mainly composed of an isolated modular multilevel matrix converter (I-M3C), which can achieve single-stage three-port power conversion. First, the topology of the I-M3C is introduced. Then, a simple modulation scheme is provided to achieve single-stage three-port power conversion, and the operating principles of the I-M3C are given in detail. In addition, a control strategy based on dual- dq coordinate system is designed, which can achieve stable operation without the complex multistage coordinated control and voltage-balancing control strategies. Finally, the effectiveness of the proposed control strategy is verified through a 10-kV/2-MW full-power simulation platform, and a 100-V/1-kW scaled-down experimental prototype is built to further demonstrate the correctness of the proposed I-M3C
Predefined-Time Sliding Mode Predictive Current Control for Disturbance Suppression and Dynamic Response Improvement in SPMSM Drives
No full textThis article proposes a novel predefined-time sliding mode predictive current control (PDOSMPCC+ HDO) technique to simultaneously enhance disturbance rejection and dynamic response in surface-mounted permanent magnet synchronous motor (SPMSM) drives. Specifically, a composite disturbance predictive model incorporating both slowly varying disturbance and sixth current harmonic disturbance is developed. A predefined-time reaching law (PTRL) and corresponding sliding mode disturbance observer are proposed to effectively estimate the slowly varying disturbance, while the sixth harmonic disturbance is estimated using a frequency-domain harmonic disturbance observer with a specially designed filter. A PTRL-based reference trajectory is defined for the PDO-SMPCC+HDO cost function to adjust the current approach trajectory. Finally, an integrated predictive control scheme is developed by minimizing the cost function. Experimental results on an SPMSM test bench verify the superior disturbance suppression and tracking capabilities of the proposed strategy
Consideration of inequalities in effectiveness trials of mHealth applications – a systematic assessment of studies from an umbrella review
No full textInvestigation of NOx emission reduction using air staging from biomass and residue combustion in an entrained flow combustion reactor
No full textBiomass is an important source of energy and heat production. Nitrogen oxides can be emitted through combustion, which can cause environmental and health issues. The nitrogen content of biomass varies extremely depending on the source, with primary sources such as wood usually containing low nitrogen contents while waste streams have higher nitrogen content, leading to higher NOx production. This study investigates the NOx emissions from two pulverized fuels with different characteristics, namely torrefied wood and dry digestate, as well as nitrogen content and the potential of NOx reduction through air staging. The former fuel is selected as a usual high-caloric biomass fuel and the latter as the source from a waste stream. The experiments were conducted in an entrained flow combustion reactor, which allows for a decoupling of the combustion parameters (temperature, stoichiometric ratio). The effect of the combustion temperature was only pronounced for the dry digestate combustion. Air staging reduced the NOx emissions from both fuels by up to 80% at higher combustion temperatures. However, since the digestate displayed higher NOx emissions, the final NOx levels did not reach below 200 mg/Nm3 at 6% O2. Therefore, it is important to investigate the NOx emissions from different fuels, especially with higher nitrogen content, and the reduction potential from primary NOx reduction measures, as these are usually the most cost-effective methods
