Unit Charge Research Articles

An 18.3-MJ charging and discharging pulsed power supply system for the Space Plasma Environment Research Facility (SPERF): The subsystem for the magnetosheath coils.

3D asymmetric magnetic reconnection is an important investigation of the Space Plasma Environment Research Facility, which is being built as a user facility at the Harbin Institute of Technology in China. Four magnetosheath coils, which consist of Poloidal Field (labeled PF) coils and Toroidal Field (labeled TF) coils, are used to generate the magnetic field and plasma environment for the reconnecting experiment. A capacitor-based pulsed power supply (PPS) system with a modular design is developed to excite the magnetosheath coils to generate the required amplitude and duration of the magnetic field. The PPS system includes the PF PPS and TF PPS, which include four sets of PPSs, respectively. Each set of PF PPS and TF PPS consists of nine modules and four modules, respectively, and each module consists of a charge and discharge unit. The PF PPS can provide a pulsed current of no less than 360 kA for the corresponding PF coil at 0.11ms when the charging voltage is 20 kV, and the duration of the pulsed current from the peak to 10% of the peak is no more than 0.6ms. The TF PPS can provide a pulsed current of no less than 200 kA for the corresponding TF coil at 0.08ms when the charging voltage is 20 kV, and the duration of the pulsed current from the peak to 10% of the peak is no more than 1.6ms. The detailed design of the PPS has been discussed in this paper, and the detailed design of the main components in the discharge unit of the PPS is also given in this paper. Finally, the discharge tests of all the PPSs are carried out to verify the design of the PPSs, and the results of the PPSs in discharge tests indicate that all the PPSs meet the design requirements.

Analysis of the Triboelectrostatic Charging Behaviour of a\xa0Synthetic Sulfidic Copper Ore

In this study, several tests were performed to analyse the triboelectrostatic charging behaviour of an artificially mixed sulfidic copper ore consisting of quartz and chalcopyrite. To check the surface charge of the pure mineral samples, they were analysed in a self-developed triboelectrostatic charging unit. After that, the artificially mixed sulfidic copper ore was sorted by using a triboelectrostatic belt separator.The objective of the study is to generate basic knowledge about the triboelectrostatic charge behaviour and furthermore the sortability by using electrostatic separation. All separation tests were carried out under controlled ambient conditions.

DNA Condensation Triggered by the Synergistic Self-Assembly of Tetraphenylethylene-Viologen Aggregates and CT-DNA.

Development of small organic chromophores as DNA condensing agents, which explore supramolecular interactions and absorbance or fluorescence-based tracking of condensation and gene delivery processes, is in the initial stages. Herein, we report the synthesis and electrostatic/groove binding interaction–directed synergistic self-assembly of the aggregates of two viologen-functionalized tetraphenylethylene (TPE-V) molecules with CT-DNA and subsequent concentration-dependent DNA condensation process. TPE-V molecules differ in their chemical structure according to the number of viologen units. Photophysical and morphological studies have revealed the interaction of the aggregates of TPE-V in Tris buffer with CT-DNA, which transforms the fibrous network structure of CT-DNA to partially condensed beads-on-a-string-like arrangement with TPE-V aggregates as beads via electrostatic and groove binding interactions. Upon further increasing the concentration of TPE-V, the “beads-on-a-string”-type assembly of TPE-V/CT-DNA complex changes to completely condensed compact structures with 40–50 nm in diameter through the effective charge neutralization process. Enhancement in the melting temperature of CT-DNA, quenching of the fluorescence emission of ethidium bromide/CT-DNA complex, and the formation of induced CD signal in the presence of TPE-V molecules support the observed morphological changes and thereby verify the DNA condensation abilities of TPE-V molecules. Decrease in the hydrodynamic size, increase in the zeta potential value with the addition of TPE-V molecules to CT-DNA, failure of TPE-V/cucurbit(8)uril complex to condense CT-DNA, and the enhanced DNA condensation ability of TPE-V2 with two viologen units compared to TPE-V1 with a single viologen unit confirm the importance of positively charged viologen units in the DNA condensation process. Initial cytotoxicity analysis on A549 cancer and WI-38 normal cells revealed that these DNA condensing agents are non-toxic in nature and hence could be utilized in further cellular delivery studies.

Improved Droop Control Strategy of Multiple Energy Storage Applications in an AC Microgrid Based on the State of Charge

Distributed energy storage technology is used to stabilize the frequency and voltage of the microgrid operating in islanded mode. However, due to the inconsistent state of charge (SoC) of the energy storage unit (ESU), the active power output of the ESU cannot be shared reasonably. On the basis of stabilizing voltage and frequency, this paper presents a power exponential function droop control (PEFDC) strategy considering the SoC. In this control strategy, the ESU is allowed to adjust the output power adaptively according to its own SoC level during discharge and reaches SoC equilibrium. Simulation models are built to compare the PEFDC strategy with conventional droop control (CDC) and power function droop control (PFDC) approaches. The simulation results illustrate the superiority of the proposed control strategy over the other two methods. Finally, the hardware-in-the-loop experiment is conducted to verify the effectiveness of the PEFDC strategy.

Entropy-based theory of thermomagnetic phenomena

We show that in the linear response approximation only entropy provides coupling between thermal and electric phenomena. The dissipationless quantum currents — magnetization, superconducting, persistent and topological edge currents — do not produce and transfer entropy and may be excluded from final formulas for thermomagnetic coefficients. The magnetization energy flux, [Formula: see text], in crossed electric and magnetic fields strongly modifies the Poynting vector in magnetic materials and metamaterials, but do not contribute to the heat current. Calculating entropy fluxes of fluctuating Cooper pairs in pure and disordered superconductors, we obtained the fluctuation Nernst coefficient proportional to [Formula: see text] ([Formula: see text] is the Fermi energy). We also introduce the thermomagnetic entropy per unit charge and derive the Nernst coefficient proportional to the difference of the thermoelectric and thermomagnetic entropies. This explains the Sondheimer cancellation and high sensitivity of thermomagnetic phenomena to correlations. In 2D superconductors, the transport entropy transferred by a vortex moving through the background formed by vortex–antivortex pairs is the configuration entropy of [Formula: see text], which strongly exceeds the intrinsic entropy of vortex core. Beyond the linear response, the nonentropic forces can lead to phenomena unexpected from thermodynamics, such as vortex attraction to the moving hot spot. Quantum currents do not transfer entropy and may be used as ideal connectors to quantum nanodetectors.

Consumer Estimates of Online Quantity Surcharge Incidence Rates

Quantity surcharges represent situations in which consumers are charged unit prices for buying large packages of a product that exceed the unit prices for smaller packages. This practice challenges the commonly held assumption that discounts rather than surcharges should be associated with larger purchase quantities. While past research has established the prevalence of this pricing practice, the degree by which consumers believe quantity surcharged to be present in the marketplace has not been empirically examined. In this study, consumer estimates of the incidence rate of quantity surcharges in online shopping environments are examined through a national survey of 522 American consumers. The effects of cognitive and demographic factors on consumers' estimates for the incidence rate of quantity surcharges are empirically examined. The findings reveal significant underestimation by consumers of the prevalence of this deceptive pricing practice. Furthermore, consumer estimates are found to be affected by cognitive style, gender, income, and prior exposure to quantity surcharges.

Two Carboxyl-Decorated Anionic Metal-Organic Frameworks as Solid-State Electrolytes Exhibiting High Li+ and Zn2+ Conductivity.

A highly electronegative carboxyl-decorated anionic metal-organic framework (MOF), (Me2NH2)2[In2(THBA)2](CH3CN)9(H2O)21 (InOF; H4THBA = [1,1':4',1″-terphenyl]-2',3,3″,5,5',5″-hexacarboxylic acid), with high-density electronegative functional sites was designed and constructed. One unit cell of InOF possesses 12 negative sites that originate from the negatively charged secondary building unit [In(COO)4]- and exposed carboxyl groups on the ligand. The abundant electronegative sites can facilitate the hopping of ions in channels and thus result in highly efficient ion conductivities for various metal ions. Our results show that Li+-loaded materials have a remarkably high ion conductivity of 1.49 × 10-3 S/cm, an ion transference number of 0.78, and a relatively low activation energy of 0.19 eV. The Na+, K+, and Zn2+ ion conductivities of InOF are 7.97 × 10-4, 7.69 × 10-4, and 1.22 × 10-3 S/cm at 25 °C, respectively.

Nonlinear optical properties of a new panchromatic series of water-soluble bicationic push-pull fluorophores

Six water-soluble bications, characterized by a symmetric A+-π-D-π-A+ structure, were synthesized and comprehensively studied for their absorption and fluorescence properties, and their nonlinear optical response. Generally, the photobehavior exhibited by the six systems was found to be dependent on the molecular dimensionality and conjugation, unveiling the role of different electron-donor (dimethoxy-phenylene vs bithiophene) and electron-acceptor (methyl-pyridinium, methyl-quinolinum, and pyrimidin-pyridinium) substituents bound in different positions (ortho/para). Steady-state measurements revealed this series as a panchromatic family of dyes with noticeable absorption and emission abilities, covering the entire visible spectrum - from the near-ultraviolet to the near-infrared spectral region. Femtosecond-resolved spectroscopy disclosed the presence of ultrafast intramolecular charge transfer processes, as also predicted by TD-DFT calculations, from the central electron-rich moiety of the molecule towards the two lateral positively charged units. Further and for the first time, a solvatochromic method was successfully applied to this kind of quadrupolar double-charged compounds in order to estimate their static and dynamic second-order hyperpolarizability coefficients. Thanks to their appreciable fluorescence capability, significant Two-Photon Absorption cross-sections were also measured for all six dyes by means of the Two-Photon Excited Fluorescence technique. These findings, together with their good water solubility, designate these eye-catching fluorophores as potential candidates for bioimaging applications.

Economic analysis and configuration design for the energy storage unit of photovoltaic virtual synchronous generator based on the inertia support and primary frequency control

With the increasing proportion of distributed generation (DG) in electrical power systems (EPSs), the lack of grid inertia and damping has posed great challenges to the stability and operation of EPSs. To address these problems, the concept of a virtual synchronous generator (VSG) has been proposed. As the physical basis of virtual inertia, the energy storage unit directly affects the performance and operating cost of the VSG. In this paper, the energy change of the energy storage unit during the frequency control process is calculated. Based on this calculation, the charge and discharge behavior of the energy storage unit can be inferred according to the VSG parameters and the frequency deviation data. Then, combined with the improved battery cycle life model, the operating cost of the energy storage unit when the VSG participates in frequency control can be obtained. Based on the data provided by the British electricity system operator (ESO), a case is studied, and the effects of the control parameters and battery rated capacity on the operating cost is analyzed. The analysis results can provide an economic reference for the parameter selection and energy storage unit capacity configuration of the VSG. Moreover, the simulation results validate the accuracy and efficiency of the proposed method.

Power fluctuation control strategy of ship power system based on hybrid energy storage system

Objective Aiming at the problems of the power quality degradation of the power grid and the power distribution of energy storage devices when the load power of a ship power system fluctuates sharply, a power fluctuation control strategy based on the hybrid energy storage of batteries and supercapacitors is proposed. Methods First, based on the low-pass filtering algorithm, the power fluctuation of the ship's power system is initially allocated to the corresponding energy storage unit according to its fluctuation frequency. Then, based on the droop control strategy, the output current of each energy storage unit is adjusted according to the allocated power. Finally, based on the state of charge of each energy storage unit, the charge and discharge control of the hybrid energy storage system is conducted to smooth out the power fluctuations. Results The simulation results show that this power distribution strategy realizes the reasonable distribution of power between energy storage units and the charge and discharge power control of the energy storage system, which can effectively smooth out the load power fluctuations of the ship's power system. Conclusion The results of this study can provide valuable references for the optimal power quality design of a ship's power grid.

Design and Simulation of a 2KVA Inverter with an Overload Protector

In this research, the design and simulation of 2000VA inverter is presented. The method implemented for the design was the d.c. – a.c. inverter topologies. The d.c. – a.c. inverter circuit made use of a 555 timer, to digitally pulse the transistors on the inverter side, and the oscillating circuit, to drive the inverter. The system consists of the main inverter stage and the charging unit. These units are further subdivided into different stages. The main inverter performs the basic operation of converting the input d.c. voltage from the battery into an a.c voltage. The charging unit contains an automatic switch that charges the battery when it senses no supply from the mains. Each unit of the project was simulated individually at every different stage of the design by using a simulating software (every circuit). The waveform given at the final stage of the simulation shows that it is a modified sine wave inverter, and it successfully converts a 12V d.c. into a 220V a.c. with a load capacity of 2000VA. The inverter should be able to power the electronic device connected for a reasonable amount of hours

Symmetry mode analysis of distorted polar/nonpolar structures in A -site ordered SmBaMn2O6 perovskite

We present a comprehensive structural study of the charge-orbital ordering and magnetic phase transitions observed in the $A$-site ordered $\mathrm{SmBa}{\mathrm{Mn}}_{2}{\mathrm{O}}_{6}$ perovskite combining synchrotron radiation x-ray powder diffraction and symmetry-adapted modes analysis. In $\mathrm{SmBa}{\mathrm{Mn}}_{2}{\mathrm{O}}_{6}$, successive phase transitions in charge, spin, and lattice degrees of freedom take place with decreasing temperature at ${T}_{\mathrm{CO}1}\ensuremath{\approx}380\phantom{\rule{0.16em}{0ex}}\mathrm{K}, {T}_{\mathrm{CO}2}\ensuremath{\approx}190\phantom{\rule{0.16em}{0ex}}\mathrm{K}$, and ${T}_{\mathrm{N}}\ensuremath{\approx}250\phantom{\rule{0.16em}{0ex}}\mathrm{K}$. The main difference between the two charge-ordered phases concerns the stacking sequence along the $c$ axis, which is double for the high temperature charge-ordered phase and has led to controversy in the literature. We show that both charge-ordered phases are pseudosymmetric with respect to the ideal undistorted tetragonal structure of $A$-site ordered $R\mathrm{Ba}{\mathrm{Mn}}_{2}{\mathrm{O}}_{6}$ perovskites and lead to two nonequivalent Mn sites. However, the charge segregation stabilizes at about $0.35{e}^{\ensuremath{-}}$ in the low temperature charge-ordered phase, clearly below the nominal separation of one charge unit between ${\mathrm{Mn}}^{3+}$ and ${\mathrm{Mn}}^{4+}$ and undergoes a prominent increase in the high temperature charge-ordered phase when warming above $\ensuremath{\approx}250\phantom{\rule{0.16em}{0ex}}\mathrm{K}$. The two Mn sites are anisotropic in both charge-ordered phases but the analysis of the active modes discloses that only the low temperature charge-ordered phase displays a Jahn-Teller-like distortion for one of the Mn sites. In addition, this low temperature charge-ordered phase has polar symmetry compatible with ferroelectricity along the $a$ axis.

Ideal topological gas in the high temperature phase of SU(3) gauge theory

We show that the nature of the topological fluctuations in $SU(3)$ gauge theory changes drastically at the finite temperature phase transition. Starting from temperatures right above the phase transition topological fluctuations come in well separated lumps of unit charge that form a non-interacting ideal gas. Our analysis is based on a novel method to count not only the net topological charge, but also separately the number of positively and negatively charged lumps in lattice configurations using the spectrum of the overlap Dirac operator. This enables us to determine the joint distribution of the number of positively and negatively charged topological objects, and we find this distribution to be consistent with that of an ideal gas of unit charged topological objects.

Optimization of Static and Dynamic Charging Infrastructure for Electric Buses

The adoption of electric buses in public transport requires careful planning for the bus fleet and charging infrastructure. A mathematical model of an urban bus service was developed to support the deployment of charging infrastructure. The novelty of the model is that it incorporates infrastructure elements for both static and dynamic charging technologies at the same time. The model supports the electrification of the bus lines without route and schedule adjustments. The volume of charged energy at charging units is considered as a variable in the objective function to determine the location of charging units at minimum cost. The model was verified by a case study based on actual bus service data. It was found that the use of static chargers is more favorable if the cost of a static charging unit is less than the cost of a dynamic charger with a length of 1600 m and the charging power of static chargers is three times greater than the charging power of dynamic chargers. The relationship between charging power and the length of the dynamic charging unit was analyzed. It was noted that the use of charging power higher than 162.5 kW at dynamic charging units is not necessary.

A chance constraint approach to peak mitigation in electric vehicle charging stations

The increased penetration of plug-in electric vehicles asks for efficient algorithms to be adopted in parking lots equipped with charging units. In this paper, the peak power minimization problem for a plug-in charging station is addressed. A chance constraint approach is adopted in order to minimize the daily peak power, allowing for a tolerance on the charging service customer satisfaction expressing the probability that a vehicle leaves the station violating the agreed level of charge. Numerical simulations are provided to evaluate the performance of the proposed approach as well as to make a comparison with other techniques.

Developing Psychological Empowerment and Patient Safety Culture: A Pre-experimental Study

Aims: This study aimed to examine the development of the perceptions of the psychological empowerment and patient safety culture among Turkish nurses by implementing a training-based empowerment program for unit charge nurses.
 Methods: A pre-experimental, one-group pretest-posttest test design was used. The sample consisted of (n = 38) unit charge nurses and (n = 174) staff nurses; the program included theoretical components, group work, and individual study assignments. Data was collected using the Demographic Data Sheet, Psychological Empowerment Scale and Hospital Survey on Patient Safety Culture before, immediately after, and four months after the program. Data were analysed by percentages, repeated measures analysis of variance, and the Friedman analysis was used for the abnormally distributed data. The Cochran's Q test was used to analyze the number of events reported.
 Results: There was a statistically significant increase found in the results of the Psychological Empowerment Scale's scores on the competence and meaning subscales, the mean positive response to teamwork within the unit’s composite of Hospital Survey on Patient Safety Culture (p < 0.05), and event reporting (p < 0.001). 
 Conclusion: The results of this study suggest that creating a positive patient safety culture requires a review of the structures and processes of an organization. Creating, maintaining a desirable patient safety culture in health institutions is a long and hard process. The duration of future empowerment programs may be determined to allow for the long-term monitoring of their effects.

Supramolecular architecture formed between amidinothiourea and 2-pyridinecarboxylic acid

The single crystals of 1-(diaminomethylene)thiouron-1-ium 2-pyridinecarboxylate, (C2H7N4S)-(C5NH4COO), (1) suitable for the X-ray analysis were grown using a solution growth technique room temperature. Recrystallization of 1 in heavy water (three-times) yield respective deuterated analogue, (C2D7N4S) (C5NH4COO), (1d). The X-ray analyses show that both, protonated and deuterated, compounds crystallize in the same crystal system with quite similar lattice parameters. X-ray analysis on a single crystal of 1 measured at 100 K and RT showed that no structural phase changes were observed between RT and 100 K. At both temperatures, crystal 1 belongs to the centrosymmetric space group of the triclinic system with two molecules in an asymmetric unit. In both molecules of the asymmetric unit the opposite charged units interact each other via the same R22(8) hydrogen bonding graph that is formed by donation of the amine groups linked to the same carbon atom to both oxygen atoms of the COO– of the 2-pyridinecarboxylate anions. The 1-(diaminomethylene)thiouron-1-ium 2-pyridinecarboxylate units are interact each other via additional N–H…O and N–H…N hydrogen bonds formed between these independent hydrogen bonded R22(8) units forming layers parallel to (001) crystallographic plane. The interactions between layers is significantly weaker than within the layers since the layers interact via much weaker NH…S hydrogen bonds. Thus the (001) crystallographic plane is a cleave plane of the crystals 1. Hirshfeld surface and the analysis of 2D fingerprint plots are illustrating both quantitatively and qualitatively interactions governing the supramolecular assemblies. The compound was also characterised by the FT-IR and Raman spectroscopy. Assignment of the vibrational bands have been supported by the DFT calculations and the isotropic frequency shift.

Dynamically characterizing topological phases by high-order topological charges

We propose a new theory to characterize equilibrium topological phase with non-equilibrium quantum dynamics by introducing the concept of high-order topological charges, with novel phenomena being predicted. Through a dimension reduction approach, we can characterize a $d$-dimensional ($d$D) integer-invariant topological phase with lower-dimensional topological number quantified by high-order topological charges, of which the $s$th-order topological charges denote the monopoles confined on the $(s-1)$th-order band inversion surfaces (BISs) that are $(d-s+1)$D momentum subspaces. The bulk topology is determined by the $s$th order topological charges enclosed by the $s$th-order BISs. By quenching the system from trivial phase to topological regime, we show that the bulk topology of post-quench Hamiltonian can be detected through a high-order dynamical bulk-surface correspondence, in which both the high-order topological charges and high-order BISs are identified from quench dynamics. This characterization theory has essential advantages in two aspects. First, the highest ($d$th) order topological charges are characterized by only discrete signs of spin-polarization in zero dimension (i.e. the $0$th Chern numbers), whose measurement is much easier than the $1$st-order topological charges that are characterized by the continuous charge-related spin texture in higher dimensional space. Secondly, a more striking result is that a first-order high integer-valued topological charge always reduces to multiple highest-order topological charges with unit charge value, and the latter can be readily detected in experiment. The two fundamental features greatly simplify the characterization and detection of the topological charges and also topological phases, which shall advance the experimental studies in the near future.

Information gap decision theory (IGDT)-based robust scheduling of combined cooling, heat and power energy hubs

Energy hubs (EHs) are units wherein multiple energy carriers can be converted, stored and conditioned to simultaneously supply different energy demands. In this paper, a new model is proposed for unit commitment in renewable EHs with electric, thermal and cooling demands, different storage systems, combined heat and power (CHP) unit, boiler, electric chiller, absorption chiller, PV module, wind turbine and battery charging station (BCS). Using information gap decision theory (IGDT), day-ahead EH scheduling is done from risk-neutral, risk-averse and risk-seeking perspectives, considering the uncertainties of electric demands, BCS demands, heat demands, cooling demands, PV and wind power and electricity prices. Comprehensive models are used for storage systems considering their degradation, charging loss, discharging loss and storage loss; the ramp-up and ramp-down rate limits, start-up and shut-down costs of CHP, boiler and cooling components are considered. The effect of risk as well as effect of critical cost deviation factor and target cost deviation factor on EH operation cost and schedule of EH components is investigated. The findings indicate that the sensitivity of EH operation cost may be very different with respect to different sets of uncertain input data. The findings also show the significant effect of risk-awareness on schedule of EH components and its operation cost.

Design of Compact Solid-State Modulator for High-Power Electromagnetic Pulse Generation

The proposed compact solid-state modulator for the generation of high-power electromagnetic (HPEM) pulses uses a lithium polymer battery as the input power source and is capable of achieving a 100-Hz pulse discharge rate with a peak voltage of 400 kV for 2 min. The developed pulse generator consists of two charging units. The primary charging unit is designed to work with 200-A battery current, which increases switching losses and temperature increments at the main switch. To compensate the problems, a half-bridge three-phase structure is connected to transformers via the proposed delta-star connection that decreases the turns ratio of the three-phase transformer effectively. Furthermore, the resonant components are intentionally placed on the secondary side of the three-phase transformer, which is characterized by low current and high voltage conditions. The secondary charging unit uses the resonance between the two capacitors, and the inductor must protect not only the controller, which is susceptible to HPEM pulse effects, but also the output rectifying diodes of the primary charging unit from the peak 20-kA pulse discharging effect. The design procedures and analysis are verified with simulations for each charging unit. The experimental results using various loads, including the actual tesla transformer, validate the system performance and confirm a 94% power efficiency with a peak power density of 431 W/L.