Single-phase Systems Research Articles

An integrated method of extended STPA and BN for safety assessment of man-machine phased-mission system

Man-Machine Phased-Mission System (MMPMS) usually demands the cooperation of operators with different responsibilities and machines to accomplish multi-phase missions. Its machine configuration and human organization structure may change across phases, and phase dependencies of machine failures and human errors may exist. In current studies, the safety of man-machine system is usually analyzed qualitatively by System Theoretic Process Analysis (STPA) and assessed quantitatively by the integration of STPA with Bayesian Networks (BN). These studies only focus on single-phase systems and conduct single-phase BN while cannot address the features of MMPMS. In this paper, a qualitative analysis and quantitative assessment method for phase dependencies is proposed and integrated into the method that combines STPA and BN. Firstly, four types of phase dependencies in MMPMS are identified. Secondly, new mapping rules for phase dependencies are proposed to integrate single-phase BN into a multi-phase BN. Thirdly, the quantitative assessment method for phase dependencies considering the effects of human organization structure changes are proposed to quantify the parameters of multi-phase BN. Fourthly, the safety of MMPMS can be assessed through multi-phase BN. Finally, an Unmanned Aerial Vehicle system with three-phase missions is presented as a case study to demonstrate the effectiveness of the proposed method.

Stabilization of gels and emulsions in the ternary water/eugenol/poloxamer 407-system: Physicochemical characterization and potential application as encapsulation platforms

The ternary system water/eugenol/poloxamer 407 can form a variety of phases that are strongly influenced by the mixture composition and the thermal history of the system. In this study, we investigated the stabilization of emulsion and gel-like systems in which eugenol is encapsulated in a poloxamer 407 matrix. Our results reveal the complex interplay between poloxamer 407 and eugenol compositions in the stabilization single-phase systems at 25ºC. Increasing concentrations of poloxamer were found to incorporate higher amounts of eugenol into emulsion-like dispersions, effectively preventing coalescence and Ostwald ripening. However, high concentrations of poloxamer 407 induced gelation of these dispersions, resulting in eugenol-loaded poloxamer 407 gels. The thermal annealing of the emulsions at 65°C for 1 h followed by equilibration at room temperature allows the extension of the compositional range for the formation of homogeneous single-phase systems providing a strategy to modulate the phase diagram of the ternary system. Additionally, the encapsulation of hydrophobic pesticides in gel-like matrices was investigated, showing uniform distribution and consistent loading capacity (approximately 0.70 % w/w) across different pesticides which may contribute to facilitate the environmental distribution and efficacy of the encapsulated molecules. This research highlights the potential of eugenol/poloxamer 407-based systems as an environmentally friendly platform for the encapsulation and delivery of hydrophobic active molecules, offering a versatile solution for various applications.

Rapid determination of 54 dye components in hair dyes by liquid chromatography coupled to quadrupole orbitrap high-resolution mass spectrometry.

Chemical hair dye components can have allergenic, reproductive, and carcinogenic risks. Detecting restricted and prohibited ingredients in these products is challenging due to product diversity, isomer separation, instability, and wide polarity range. A method was developed using HPLC-high-resolution mass spectrometry for the qualitative and quantitative analysis of 54 hair dye components in various products. Samples were extracted with a 70% methanol solution, ultrasonicated in an ice bath, centrifuged, filtered, diluted with 25% methanol solution and 25% methanol solution containing 0.05% D-isoascorbic acid. Separation was achieved using an ACE Excel 3 C18 column (2.1 mm × 150 mm, 3 μm) with analysis conducted via quadrupole Orbitrap mass spectrometry. It showed good linear correlations, with detection limits of 0.1-23.5 ng mL-1, and quantitation limits of 0.2-78.1 ng mL-1. Average recovery ranged from 60.0% to 118.4%, with repeatability from 4.0% to 14.9%. Stability was confirmed within 48 hours. When applied to 20 batches of commercially available hair dyes, 24 hair dye components were found within permissible levels. The method is crucial for quality control of hair dyes, covering 10 common prohibited and 44 permissible hair dye components outlined in the Safety and Technical Standards for Cosmetics (2015 Edition). Compared to the standard methods, it can separate isomers in a single mobile phase system within 15 minutes in positive ion mode while maintaining sensitivity for phenol, hydroquinone, and other components in negative ion mode. Moreover, the pre-treatment strategy significantly improved stability and accuracy, enabling precise analysis of the 54 hair dye components.

Diffusive Trends in Concentrated Oppositely-Charged Polyelectrolyte Solutions and Onset of Glassy Dynamics.

We utilize single particle tracking studies to investigate the diffusion of polylysine through concentrated matrices of cationic polylysine and anionic polyglutamic acid with no added salts. These studies show that diffusivity has a strong apparently exponential dependence on concentration in crowded systems that does not appear to be a function of the charge sign. These trends are consistent in both single-phase systems prepared at concentrated conditions and polymer-rich coacervate phases formed from dilute phase-separating systems. The likely origin of this behavior is the onset of glassy dynamics spurred by a decrease in plasticization by water and the large excluded volume associated with charge-bearing species. This effect can be contextualized through free volume-based theories such as the Vrentas-Duda model. Overall, we obtain dynamic behavior that is distinctly different from behavior observed in more dilute systems and warrants further investigation.

A Dual control strategy for improved power quality in grid-tied off-board bidirectional electric vehicle charger

Electric vehicle (EV) chargers face significant challenges in maintaining grid power quality (PQ) and ensuring efficient power management during grid-to-vehicle (G2V) and vehicle-to-grid (V2G) operations. Additionally, they must seamlessly switch to vehicle-to-load (V2L) mode during grid disturbances to provide uninterrupted power supply (UPS) for domestic loads. This article explores a dual control approach incorporating adaptive model predictive direct power control (AMP-DPC) on the rectifier side and adaptive direct power control (ADPC) on the dual active bridge (DAB) side to address these challenges. The AMP-DPC employs a control strategy referred to the second-order generalized integrator (SOGI) which estimate synchronizing voltage templates specifically designed for single-phase systems. The proposed optimization control aims to mitigate the cost function value by selecting appropriate switching modes. The optimized function is independent of the weighting factor, expressing the optimal modulation function across various weighting factors without additional design or selection. The current reference used by the charger is designed to ensure that the power factor remains at closer unity throughout G2V and V2G modes. The proposed control algorithm ensures the grid current remains low in harmonics during G2V, V2G, and V2L modes of operation. The experimental validation of the proposed control strategy is performed in the laboratory on a 0.5 kW off-board electric vehicle charger (EVC) prototype under various conditions to demonstrate its effectiveness in compliance with the IEEE 519–2022 standard.

Effect of Chevron Angles on the Thermal Performance of Corrugated Plate Heat Exchanger (CPHEs)

Corrugated plate heat exchangers (CPHEs) possess a greater surface area for heat transfer and a heightened level of turbulence as a result of the corrugations. This study presents an experimental analysis comparing the thermal performance of a flat plate heat exchanger and a corrugated plate heat exchanger (CPHE) with varied corrugation angles. The analysis was conducted using water as the test fluid. The comprehensive testing has been carried out on CPHEs with different chevron angles (β) of 30°/30°, 45°/45°, and 60°/60°. Experimental data is collected under steady- state conditions, with a single phase (water-water) system, covering Reynolds numbers (Re) ranging from 900 to 1250. The test fluid's mass flow rate, ranging from 0.05 to 0.16 kilograms per second, is measured together with the accompanying steady state temperatures. Each plate was equipped with four thermocouple sensors to detect the bulk temperature of the cold and hot fluids at the intake and output. The performance was evaluated using both parallel and counterflow configurations. Experimental observations are utilized to estimate the temperature difference (∆T) between the inlet and output streams, the logarithmic mean temperature difference (LMTD), and the exergy (E). The measured ∆T and E values for corrugation angles (30°, 45°, and 60°) of CPHE were compared to those of flat plate heat exchangers. For corrugation angles of 30°, 45°, and 60°, the values of ∆T and E (efficiency) increase as the mass flow rate of the fluid increases. An increase in the corrugation angle leads to an increase in turbulence in the flow, which in turn enhances heat transmission. In addition, the thermal effectiveness (ε) was calculated using the NTU method and compared for all of the plates. Key Words: Corrugated plate heat exchanger, Thermal performance, Chevron angle, heat transfer coefficient.

A multifunctional inverter power quality coordinated optimization strategy based on comprehensive evaluation

The large-scale integration of renewable energy sources and power electronic devices has led to increasingly dispersed and networked characteristics of power quality disturbances in distribution systems. Traditional control devices, limited by their fixed-point control, no longer meet the development needs of modern distribution systems. Considering the distribution and structural characteristics of the current new-type sources and loads, a multifunctional inverter power quality coordinated control strategy based on comprehensive evaluation is proposed. This strategy aims to achieve power quality coordinated control by utilizing optimal compensation capacity while the grid-connected inverter provides active power output. Firstly, the traditional ipiq power quality detection method is analyzed and improved to enable detection of harmonics, reactive power, and three-phase imbalance currents in single-phase systems or three-phase four-wire systems. Secondly, in the power quality assessment, a balanced algorithm is employed to obtain the comprehensive evaluation index of power quality, thereby improving the deficiencies of single-weight evaluation. Next, to ensure the grid-connected inverter achieves optimal power quality coordinated control with minimal compensation capacity, an optimization compensation function is established between compensation capacity and comprehensive power quality index. This function is optimized using non-dominated sorting genetic algorithm to enhance equipment utilization and system economy. Finally, the feasibility and effectiveness of the proposed method are validated through simulations, demonstrating the achievement of optimal capacity configuration for power quality coordinated control while ensuring active power output by the grid-connected inverter.

On the numerical simulation of a phase change material melting inside periodic structures: from validation to optimization

Nowadays, numerical models are considered powerful design tools, which are largely used in several engineering applications. When applied to heat transfer applications, they have already been shown to be reliable, especially in single phase systems. When considering two-phase heat transfer, and in particular solid-liquid phase change processes, the numerical tools must be carefully handled. Thus, this paper follows the critical literature on the application of numerical methods to simulate and optimize latent thermal energy storages to show how, in most cases, the common geometrical and numerical approximations should not be applied because they might lead to misleading solutions. Starting from reliable experimental results collected during melting process of a paraffin wax inside 3D periodic structures, different simulation approaches are proposed, and their advantages and disadvantages are discussed. The results show that, when dealing with certain complex 3D structures, 2D approximations cannot reliably capture the phase-change phenomenon. The validated tool also allowed to identify the optimum pore size to maximize the solid-liquid phase change. This work can be considered as a reference for future numerical studies on the solid-liquid process inside 3D structures.

Overview of Open-Loop Frequency Estimation Techniques for Grid Synchronization of Single-Phase Power Converters

Open-loop synchronization techniques allow to overcome the stability issues to which closed-loop techniques are subject. Most open-loop techniques differ in their Quadratic Signal Generator and their frequency estimation method. In this paper, an overview of the main frequency estimation methods for single-phase power systems is presented. A description of each technique with their structure for numerical implementation is carried out. A comparative study of those frequency estimation methods is performed according to three test scenarios in order to evaluate the robustness of each method. Recommendations for the selection of the technique is given according to the simulation results.

Phase field modeling and numerical algorithm for two-phase dielectric fluid flows

We develop a method for modeling and simulating a class of two-phase flows consisting of two immiscible incompressible dielectric fluids and their interactions with imposed external electric fields in two and three dimensions. We first present a thermodynamically-consistent and reduction-consistent phase field model for two-phase dielectric fluids. The model honors the conservation laws and thermodynamic principles, and has the property that, if only one fluid component is present in the system, the two-phase formulation will exactly reduce to that of the corresponding single-phase system. In particular, this model accommodates an equilibrium solution that is compatible with the zero-velocity requirement based on physics. This property leads to a simpler method for simulating the equilibrium state of two-phase dielectric systems. We further present an efficient numerical algorithm, together with a spectral-element (for two dimensions) or a hybrid Fourier-spectral/spectral-element (for three dimensions) discretization in space, for simulating this class of problems. This algorithm computes different dynamic variables successively in an un-coupled fashion, and involves only coefficient matrices that are time-independent in the resultant linear algebraic systems upon discretization, even when the physical properties (e.g. permittivity, density, viscosity) of the two dielectric fluids are different. This property is crucial and enables us to employ fast Fourier transforms for three-dimensional problems. Ample numerical simulations of two-phase dielectric flows under imposed voltage are presented to demonstrate the performance of the method herein and to compare the simulation results with theoretical models and experimental data.

Continued Investigation of Arc Flash in Single-Phase Systems: Threshold for Possible Hazards

Continued Investigation of Arc Flash in Single-Phase Systems: Threshold for Possible Hazards

Mathematical Modeling of the Drug Particles Deposition in the Human Respiratory System—Part 1: Development of Virtual Models of the Upper and Lower Respiratory Tract

In order to carry out mathematical modeling of the drug particles or drop movement in the human respiratory system, an approach to reverse prototyping of the studied areas based on the medical data (computed tomography) results is presented. To adapt the computational grid, a mathematical model of airflow in channels of complex geometry (respiratory system) has been developed. Based on the data obtained, the results of computational experiments for a single-phase system are presented.

An Efficient DC-AC Power Integration Model for Single-Phase Systems, Simulated in MATLAB

In the face of growing clean energy demands, this study presents a model for integrating Direct Current (DC) sources into the existing Alternating Current (AC) grid. The model is based on a single-phase system where a DC source is added. A converter, designed using the synchronous reference frame, is proposed to address integration issues. This converter allows for the control of both active and reactive power using a dq reference frame. A Proportional-Integrator (PI) controller is chosen for this purpose. To generate the necessary operational references, a Phase-Locked Loop (PLL) is used. An LCL filter is also incorporated based on its performance quality. The entire model is simulated in MATLAB, and the output obtained confirms the model’s ability to control both active and reactive power when integrating DC with AC and T. This work significantly contributes to the efforts of integrating clean energy into our existing grid systems.

Cyclic Silicon Organic Copolymers: Synthesis and Investigation. Review

This paper considers the synthesis and investigation of cyclic silicon-organic polymers with mono- and polycyclic fragments in the side chain. For obtaining monocyclic polymers, the hydrosilylation reaction of 1-hydro-3-vinylhexamethylcyclotetrasiloxane was used. The reaction was conducted in a CCl4 solution at 75°C in the presence of Speier’s catalyst (H2PtCl6  6H2O) to produce a viscous-flow at room temperature polymer. The polymers were studied by NMR spectroscopy. Poly(carbosiloxane) with cyclic fragments in the methyl-siloxane backbone was synthesized by the hydride polyaddition of divinylorganocyclosiloxane with dihydrodimethylsiloxane. A semi-quantitative assessment conducted using NMR spectroscopy revealed the ratio of isomeric 1,3- and 1,5-cyclic structures as 1:1. X-ray diffraction studies indicated that copolymers are single-phase amorphous systems. Also, in the review, synthesis and studies of carbosiloxane copolymers containing flexible dimethylsiloxane and decaorganotricyclodecasiloxane fragments in the backbone are discussed. Hydride polyaddition of divinyl-containing compounds was carried out for -dihydridedimethylsiloxanes of various lengths. The synthesized copolymers were characterized by the X-ray diffraction method and TGA.

3-level inverter based compensator for power quality enhancement using proposed Trianguzoidal PWM technique

In today’s scenario, the integration of a grid-connected load system with a hybrid energy system (HES) is encouraged to improve the reliability of the system. With the stunning rise in nonlinear loads in HES over the last two decades, the power quality (PQ) of the system has emerged as a paramount concern in contemporary times. The power quality problems include the injection of harmonics in the source current, low input power factor, poor voltage regulation, the burden of reactive power, etc. So, to mitigate these power quality problems in a single-phase distribution system, a 3-level Cascade H-bridge (CHB) inverter-based shunt active power filter (SAPF) is employed alongside a proposed Trianguzoidal pulse width modulation (TRZ PWM) strategy. The single-phase distribution system with SAPF is simulated in fixed and dynamic load conditions to check the system’s efficacy. The proposed PWM techniques for SAPF are compared with conventional PWM techniques, i.e., level shift, phase shift, and hybrid PWM techniques. Results indicate satisfactory performance of the proposed PWM techniques, exhibiting low harmonic distortion in source current, well within IEEE 519 limits, and high active filtering efficiency (AFE) compared to conventional PWM methods. Furthermore, this paper provides detailed comparisons of conventional and proposed PWM techniques in the context of active & reactive power supplied or delivered by load, source, and compensator, input power factor, harmonics in source or grid current, AFE, and individual harmonic components concerning fundamental component of source current.

Optimal number of supercapacitors per submodule in the energy storage system based on a modular multilevel converter with embedded balance control

As renewable energy sources interconnected to the electric grid increase, deploying distributed energy storage systems along the grid is a viable solution to sustain grid stability. One of the critical aspects of any energy storage system is its efficiency in transferring power to the grid. Another important aspect is managing high power levels in a short time and being easily expandable in terms of energy capacity and power handling. For this reason, supercapacitors are suitable energy storage devices to fulfill these requisites. This article focuses on analyzing the losses and improving the efficiency of a supercapacitor energy storage system based on a modular multilevel converter, which accomplishes all the abovementioned functions and capabilities. The analyzed energy storage system is based on submodules, including the power electronic interface and the supercapacitors. Hence, the system can be easily expanded because the submodule provides the functions of balancing the energy storage devices, the DC/AC, and the DC/DC conversions by using the modular multilevel converter topology approach. Therefore, any number of submodules can be connected, and the operator can make an array of the desired power, energy, and voltage ratings. This study details a probabilistic loss analysis for the proposed supercapacitor energy storage system and presents a case study using 3000F supercapacitor cells for a 6.6 kW single-phase system. The improved submodule version is validated through simulations and experimentally with a lab-scale prototype. The results show how the proposed methodology increases the system's overall efficiency with a 95 % confidence level.

Multi-phase shear thickening fluid based on ionic liquid dispersion medium for impact resistance and wear protection

Shear thickening fluids (STFs) have attracted increasing attention as smart materials with unique rheological properties. However, the preparation of STFs usually relies on a composite system of spherical nanoparticles with polyethylene glycol. In this work, novel multi-phase STFs (ILSTFs) were prepared in an ionic liquid by incorporating nanosized SiO2 and rod-shaped calcium metasilicate (CaSiO3) particles as a dispersed phase. Compared to traditional STFs, ILSTFs demonstrate excellent thermal stability. Rheological tests indicate that ILSTFs exhibit continuous shear thickening behavior, resulting in excellent energy absorption and impact wear resistance. In addition, ILSTFs can serve as a new type of lubricant. The tribological properties and impact resistance of ILSTFs were highly correlated with the shear thickening effect, with the multi-phase ILSTF system with CaSiO3 demonstrating superior impact wear resistance compared to the single-phase system. In this study, finite element analysis (FEA) is further utilized to investigate the local damage evolution and energy absorption rate of STF under impact loading, providing insights into the underlying mechanism. This ionic liquid-based STF holds promise for applications as a flexible filling component in the fields of lubrication technology and impact protection structures.

Effect of annealing temperature on the properties and the chromium oxidation state of ZnAl1.94Cr0.06O4 nanoparticles prepared by coprecipitation method

Nanostructured materials doped with Cr+3 have potential applications. However, it has been reported that heat treatment can modify the oxidation state of Cr+3, resulting in the formation of toxic Cr+6 in host matrices such as TiO2, Al2O3, SiO2, ZrO2, and Fe(OH)3. The possibility of this occurrence in nanostructured ZnAl2O4:Cr+3 has not been previously considered. In this study, we report the effect of annealing temperatures within the range of 600–1300 °C on the structure, morphology, optical properties, and, more specifically, the chromium oxidation state of ZnAl1.94Cr0.06O4 nanoparticles obtained through the coprecipitation method. The obtention of single-phase systems with a crystal size ranging from 5.25 nm to 142.75 nm was determined by X-ray diffraction and Rietveld refinement. At 800 °C, a more significant oxidation of Cr+3 was observed, evident in the increased absorption intensity of UV–vis bands associated with Cr+6 and a reduction in magnetic susceptibility at ambient temperature. At 1200 °C, a complete reduction of Cr+6 occurred, leading to the appearance of bands related to Cr+3 in the UV–vis absorption spectra and increased magnetic susceptibility; the results were confirmed by X-ray photoelectron spectroscopy. The outcomes of this study offer new insights into the thermal stability of chromium in ZnAl2O4 nanoparticles.

An Optimized Design Modeling of PV Integrated SEPIC Based Single-Phase System

An Optimized Design Modeling of PV Integrated SEPIC Based Single-Phase System

Research on Three-Phase Wireless Power Transfer System

Aiming at the problems of low power, low energy transmission efficiency, and high stress in the circuit of a single-phase wireless power transfer system, this paper proposes a wireless power transfer (WPT) system with a three-phase angle difference of 120 degrees and establishes a COMSOL multi-physics simulation model for analysis. In this simulation model, the topology of the three-phase resonant compensation network is studied in detail, and the structure of the coupling coil is designed and adjusted. Compared with the single-phase system with the same environmental conditions, air gap, and operating frequency, the simulation results show that the proposed three-phase system can effectively reduce the magnetic flux leakage, reduce the stress in the circuit, and significantly improve the energy transmission efficiency. In order to verify the reliability of the simulation results, an experimental platform was built. The experimental results show that the efficiency and coupling degree of the new system are significantly improved at the resonant frequency of 47.5 kHz, and the stress in the circuit is also significantly reduced.