Discharge Duration Research Articles

Investigation on plasma ionization process of a micro-cathode arc thruster

Micro-cathode arc thrusters (μCATs) are space propulsion options suitable for microspacecraft, and have recently attracted much attention because of their low electrical power requirements and simple, compact propellant systems. The plasma ionization process, however, is not currently well understood. In this study, a μCAT prototype was designed with the use of different specific materials for each component, enabling the study of the ionization process from the emissive light of excited and ionized states from different elements. ICCD emission spectroscopy and scanning monochromator measurements are conducted inside the electrode channel of a μCAT with a coaxial configuration. The excited state atomic spectral results and ionization state spectral results give us a comprehensive understanding of the behavior of neutral particles and ions during the discharge process of the μCAT. The ionization sequence follows in the order of C+, Al+, Ti+, Cu+, and Ti2+. From the duration of the spectral lines, C I has the shortest duration (16.9 μs), which shows that the ablation of the conductive film is mainly concentrated during the first half of the discharge, while anode and cathode ionization occur over the entire discharge duration. Additionally, Al+ ionization is observed during the discharge process, showing that part of the discharge energy is expended in ionizing the thruster outer shell, resulting in efficiency loss. An ionization ratio of k is proposed in this work to represent the relative ionization of the conductive film and cathode material, aiding us in determining the optimal operation conditions for lifetime extension.

Parametric investigation of W-EDM factors for machining AM60B conductive biomaterial

Wire—electrical discharge machining (W-EDM) is a precise and efficient non-traditional technology employed to cut intricate shapes in conductive biomaterials. These biomaterials are challenging to machine using traditional methods. This present study delves into the impact of various process parameters, namely discharge duration (Ddur), spark gap time (Stime), discharge voltage (Dvolt), and wire advance rate rate (Wadv). This research evaluates the impact of several factors on response variables, namely the machining rate (MR) and surface irregularity (SR), during the machining process of the AM60B magnesium alloy. The confirmation of the material used in the machining process is achieved via the utilisation of a scanning electron microscopy (SEM) image in conjunction with an energy dispersive spectroscopic (EDS) image. The experiment is designed as L9 orthogonal array by using Taguchi's approach, taking into account 4 factors with 3 levels. The objective of this experiment is to ascertain the most favourable values for machining parameters while working with AM60B magnesium alloy using brass wire. Through analysis of variance (ANOVA), the study confirms that wire advance rate (43.10%) is the most influencing parameter for machining rate and surface irregularity followed by spark gap time (33.91%) and discharge duration (11.48%). Additionally, The TOPSIS-CRITIC and the desirability approach were used in order to determine the optimum parameter combinations that provide the most favourable combined output. Confirmatory testing is used to evaluate the efficiency of the stated ideal conditions. The maximum improvement in Desirability approach is obtained at 4.56% and 4.193% for MR and SR respectively. The maximum improvement in TOPSIS approach is obtained at 1.77% and 2.78% for MR and SR respectively.

СОВЕРШЕНСТВОВАНИЕ СРЕДСТВ КОНТРОЛЯ ЭФФЕКТИВНОСТИ СИСТЕМ ЗАЖИГАНИЯ АВИАЦИОННЫХ ДВИГАТЕЛЕЙ

Relevance Aircraft engine ignition systems are one of the main elements that determine the reliability of the operation of the aircraft as a whole. Evaluating and monitoring the performance of such systems must be carried out at stages from development to operation, so the task of creating such systems is very urgent. Aim of research Development of new structures and principles of operation of digital meters of parameters characterizing the efficiency of capacitive ignition systems of aircraft engines with semiconductor spark plugs. Research methods The issues of construction are considered and the developed hardware solutions for digital meters of parameters characterizing the efficiency of capacitive ignition systems of aircraft engines with semiconductor spark plugs are presented. The structures of the meters and timing diagrams of their operation are presented, and the features of using current and voltage sensors are discussed. Results The article presents the results of the development of measuring systems for parameters characterizing the efficiency of capacitive ignition systems of aircraft engines with semiconductor spark plugs — a meter for the criterion of the ignition ability of the ignition system as a function of the parameters of spark discharges in spark plugs and a universal meter for the duration of spark discharges, which allows measuring the duration of discharges of oscillatory and aperiodic types. The proposed technical solutions make it possible to improve the quality and completeness of assessing the efficiency of spark discharges in semiconductor spark plugs. The developed structures belong to the class of systems with «hard» operating logic and perform the necessary measuring operations with maximum speed.

Residual Stress Effects of Multiple Thermal Material Loads due to a Roughing-Finishing Sequence of Electrical Discharge Machining Processes

Being a manufacturing process based on thermal material removal, it has been known for decades that Electrical Discharge Machining (EDM) affects the properties of surface layers of machined workpieces, notably by inducing residual stresses. These stresses are undesirable as they can contribute to crack formation in ED machined parts in on-load operation. Thus, their minimization is preferable. In this research the influence of different combinations of EDM parameters (namely discharge duration and discharge current) on characteristics of residual stresses is studied and compared. However, industrial ED machining usually consists of a sequence of process regimes that each represents a thermal load for the material and consequently each causes an individual profile of residual stress. Therefore, the resulting effect of these combined loads is also investigated. The findings contribute to the knowledge of the process signature of Electrical Discharge Machining as well as they allow for improved planning of industrial EDM processes.

Design, manufacturing and thermal analysis of a honeycomb-inspired PCM-filled cold plate

In recent times, electric vehicles (EVs) have been seen as an environment-friendly alternative to conventional vehicles. Lithium-ion battery packs power the EVs today due to their low self-discharge and higher efficiency as compared to the other battery chemistries. These batteries operate in an optimal temperature range. This calls for effective thermal management of these battery packs. Cold plates are a viable method for the thermal management of these packs. An active method of thermal management uses a coolant flowing through the cold plates, maintaining the battery pack temperature. Another approach to cold plate design is the use of Phase Change Materials (PCMs) as a passive cooling method. This paper suggests possible designs for the cooling plates, one using an active method of cooling and the other based on a PCM. The design considerations, thermal performance and manufacturing methods for both are discussed and analyzed. Results show that the PCM-based cold plate maintains the temperature with a very low thermal gradient for relatively shorter discharge durations, whereas the coolant flow-based cold plate shows a better performance for longer discharge durations. Finally, a 3-stage manufacturing process involving - Blanking, Indenting, and Projection Welding has been proposed to manufacture the two types of cold plates.

Optimal planning of electricity-gas coupled coordination hub considering large-scale energy storage

Large-scale long-duration energy storage (LDES), like compressed air energy storage (CAES) and liquid air energy storage (LAES), is promising for high-penetration renewable energy consumption in the city-scale integrated energy system (IES). Due to high installation costs and challenges in decentralized control of distributed energy storage, this paper proposes an optimal planning model for an urban electricity-gas coordination hub (UEGCH) with centralized energy storage using large-scale LDES. Firstly, the UEGCH with energy cascade utilization is designed, where process-based linearized models of advanced adiabatic compressed air energy storage (AACAES) and LAES are established to make a trade-off between solving accuracy and speed. Then, a city-scale integrated electricity and gas system (IEGS) is constructed with multiple regions considering line-packing. Finally, a multi-scenario planning method is proposed based on X-means for scenario reduction, and the global optimum is obtained through linearization. Results show that compared with traditional gas storage tank (GST) in the UEGCH, the utilization of AACAES and LAES requires as little as 7 % and 0.7 % of the construction volume with lower carbon emissions and can be cost-competitive in terms of future advancement. As for different EESs, in contrast to the energy-based energy storage (EBES) (i.e., battery (BT)), the levelized cost of energy (LCOE) of the capacity-based energy storage (CBES), which includes AACAES and LAES, can be reduced by nearly 0.1 $/kWh, bringing an annual economic benefit of $ 3 million. Besides, the discharge duration of CBES can be increased to 13 h, demonstrating the application prospect in 100 % renewable consumption and islanding operation. Compared with AACAES, LAES can reach 11.67 times the energy density, with a drop of 6.11 % in operating cost. The abilities of EBES and CBES to locally consume renewables are respectively weaker and stronger than that of power-to-gas (P2G) combined with line-packing. Meanwhile, this paper further analyzes the impacts of temperature, discharge duration, renewable penetration, energy tariff, and demand on the operation and sizing of centralized energy storage.

Modification of streamer-to-leader transition model based on radial thermal expansion in the sphere-plane gap discharge at high altitude

Historically, streamer-to-leader transition studies mainly focused on the rod-plane gap and low altitude analysis, with limited attention paid to the sphere-plane gap at high altitude analysis. In this work, sphere-plane gap discharge tests were carried out under the gap distance of 5 m at the Qinghai Ultra High Voltage (UHV) test base at an altitude of 2200 m. The experiments measured the physical parameters such as the discharge current, electric field intensity and instantaneous optical power. The duration of the dark period and the critical charge of streamer-to-leader transition were obtained at high altitude. Based on radial thermal expansion of the streamer stem, we established a modified streamer-to-leader transition model of the sphere-plane gap discharge at high altitude, and calculated the stem temperature, stem radii and the duration of streamer-to-leader transition. Compared with the measured duration of sphere-plane electrode discharge at an altitude of 2200 m, the error rate of the modified model was 0.94%, while the classical model was 6.97%, demonstrating the effectiveness of the modified model. From the comparisons and analysis, several suggestions are proposed to improve the numerical model for further quantitative investigations of the leader inception.

Ictal activity is sustained by the estrogen receptor β during the estrous cycle

Catamenial epilepsy, defined as a periodicity of seizure exacerbation during the menstrual cycle, affects up to 70 % of epileptic women. Seizures in these patients are often non-responsive to medication; however, our understanding of the relation between menstrual cycle and seizure generation (i.e. ictogenesis) remains limited. We employed here field potential recordings in the in vitro 4-aminopyridine model of epileptiform synchronization in female mice (P60–P130) and found that: (i) the estrous phase favors ictal activity in the entorhinal cortex; (ii) these ictal discharges display an onset pattern characterised by the presence of chirps that are thought to mirror synchronous interneuron firing; and (iii) blocking estrogen receptor β-mediated signaling reduces ictal discharge duration. Our findings indicate that the duration of 4AP-induced ictal discharges, in vitro, increases during the estrous phase, which corresponds to the human peri-ovulatory period. We propose that these effects are caused by the presumptive enhancement of interneuron excitability due to increased estrogen receptor β-mediated signaling.

Outcomes of cutting Seton in treatment of high peri-anal fistula in Soba University and Ibrahim Malik hospitals, Khartoum, Sudan

Objective: To evaluate and understand the outcomes and efficacy of cutting Seton technique, widely used for high peri-anal fistulas. Methodology: This hospital-based cross-sectional study was conducted at Soba University and Ibrahim Malik hospitals, encompassing 60 patients diagnosed with peri-anal fistulas from July to December 2022. Demographics, comorbidities, incontinence, surgical procedures, and diagnostic modalities were documented and analyzed to understand the clinical characteristics and outcomes of the cutting Seton technique. Results: Out of 60 patients, 83.3% were males and 16.7% females, with an average age of 37.5 years. The majority had discharge history (88.3%), and 40% presented with comorbidities. Park’s classification was used to categorize fistula types, revealing predominance in intersphincteric (36%) and transsphincteric (22%) locations. Cutting Seton success rate of 82%, with discharge duration averaging eight weeks and recurrence at five weeks. No significant differences in postoperative outcomes were found relative to the material used for Seton or the timing of Seton removal. Conclusion: The study affirms the efficacy of the cutting Seton method in managing high peri-anal fistulas with a high success rate and manageable recurrence. The findings necessitate tailored patient selection and underscore the importance of comorbidities and clinical characteristics in determining treatment outcomes.

INTEGRATION OF THERMAL ENERGY STORAGE MATERIALS IN HEAT PIPE EVACUATED TUBE SOLAR COLLECTOR SYSTEMS FOR ENHANCED SOLAR THERMAL PERFORMANCE

This study investigates integrating thermal energy storage materials (TESM) with a heat pipe evacuated tube solar collector (HP-ETSC) in a water tank. Three TESMs (paraffin wax, RT27, and RT35) were examined numerically using COMSOL software, and experiments were conducted. Different design parameters were discussed, including water tank thickness, TESM tank thickness, TESM types, flow rate, and environmental conditions. The integration of TESM into the HP-ETSC allows the evaluation of various thermal performances, including average water tank temperature, hot water outlet temperature, and duration of hot water availability after sunset. The findings indicate a maximum temperature difference of approximately 37°C at 13:00 on March 19 without TESM. However, with RT35, the temperature difference is around 34.27°C, and with RT27, it is approximately 33.4°C. Additionally, the temperature difference is approximately 2°C higher when TESM is not utilized during the three months at sunset. These results demonstrate improved thermal performance compared to a similar system without TESM. Thermal energy transmission from TESM to water is relatively low, resulting in slightly higher outlet water temperature at night. During cloudy periods, RT27 and RT35 TESM types maintain their melting temperature from 11:00 to 20:00. A water storage tank thickness of 35 mm yields the highest temperature difference with RT27 and RT35 TESM. Increasing TESM thickness allows for more mass and latent heat storage, leading to up to 3.5 hours of heat release. On a mostly sunny day, such as January 9, the HP-ETSC stops heat release around 16:30 without TESM, while the TESM plates prolong the discharge duration by three hours.

The Impact of Wind Power and Load Power Fluctuations on Energy Storage Sizing

The study presents a method of taking into account the impact of wind power and load power fluctuations on the energy storage sizing, comprised of batteries of identical capacity. To account the impact, two methods of calculating the difference between wind power generation and load consumption were presented over some time interval: 1st and 2nd order difference methods. Each of the methods can be parameterized and non-parameterized method with and without taking into account parameters respectively, where the parameters are: discharge current, required discharge duration, depth of discharge, battery capacity, Peukert’s constant, discharge time from 100% capacity, ambient temperature and wind power prediction error. Using the parameterized method compared allows to refine the value of the number of batteries. Using the 2nd order difference method compared to the 1st order difference method can significantly reduce the required number of batteries.

Uncovering the Mechanisms behind the Limited Discharge Duration of Silicon-Air Batteries with Alkaline Electrolytes

The demand for electronic devices with high storage capacities and long-lasting batteries has motivated the development of new battery systems. Metal-air and semiconductor-air batteries are particularly interesting due to their high capacity densities due to the use of air for the cathode reaction. The Si-air battery was introduced as a battery system that operated with a room-temperature ionic liquid or KOH as the electrolyte.[1,2] However, the practical capacity density is reduced to a fraction of the theoretical value in liquid electrolytes, and the passivation of the silicon anode in aqueous electrolytes is a major challenge.[3,4] Increasing the surface area of the Si electrode can reduce the local reaction rate and enable the dissolution of the reaction products, but it also increases the overall corrosion rate. A threshold temperature and the addition of fresh electrolyte solution can also extend the discharge duration.[3,5] Silicon-air batteries have the potential to become the next generation of batteries, as they are made from non-critical raw materials and have a high theoretical capacity. However, silicon-air batteries using alkaline electrolytes suffer from early passivation and termination of discharge. To understand this process, we investigated the correlation between dissolved silicon in the electrolyte and the discharge duration until passivation. Our findings revealed that silicate enrichment in the electrolyte reduces the flow of reaction products away from the silicon surface, leading to rapid oxidation and passivation of the surface.[6] We utilized various techniques, including electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM), to investigate this phenomenon further. Our results showed that the silicate concentration in the electrolyte plays a crucial role in determining the performance of silicon-air batteries. A lower concentration of silicates in the electrolyte leads to sustained discharge, while a higher concentration results in early passivation and termination of discharge.In conclusion, our investigation highlights the critical role of silicates in the performance of silicon-air batteries utilizing alkaline solutions. Our findings suggest that controlling the concentration of silicates in the electrolyte is crucial to ensure the sustained discharge of these batteries. This study provides essential insights into the mechanisms governing the passivation of silicon surfaces in alkaline electrolytes, which will aid in the development of more efficient and sustainable energy storage solutions.[1] G. Cohn, D. Starosvetsky, R. Hagiwara, D. D. Macdonald, Y. Ein-Eli, Electrochem. commun. 2009, 11, 1916–1918.[2] X. Zhong, H. Zhang, Y. Liu, J. Bai, L. Liao, Y. Huang, X. Duan, ChemSusChem 2012, 5, 177–180.[3] Y. E. Durmus, Ö. Aslanbas, S. Kayser, H. Tempel, F. Hausen, L. G. J. G. J. de Haart, J. Granwehr, Y. Ein-Eli, R.-A. A. Eichel, H. Kungl, Electrochim. Acta 2017, 225, 215–224.[4] Y. E. Durmus, S. Jakobi, T. Beuse, Ö. Aslanbas, H. Tempel, F. Hausen, L. G. J. de Haart, Y. Ein-Eli, R.-A. Eichel, H. Kungl, J. Electrochem. Soc. 2017, 164, A2310–A2320.[5] S. Sarwar, M. Kim, G. Baek, I. Oh, H. Lee, Bull. Korean Chem. Soc. 2016, 37, 997–1003.[6] R. Schalinski, S. L. Schweizer, R. B. Wehrspohn, ChemSusChem 2023, DOI 10.1002/cssc.202300077.

(Invited) Understanding Capacity Fade Behavior in Aqueous Organic Redox Flow Batteries Via Zero-Dimensional Models and High-Throughput Cell Cycling

Aqueous Organic Redox Flow Batteries (AORFBs) have emerged as promising and potentially disruptive technologies for the storage of electrical energy from intermittent renewable sources for use over long discharge durations when the sun isn’t shining and the wind isn’t blowing. AORFBs could become preferred over Li-ion batteries for grid-scale stationary storage due to their potentially low-cost active materials made of Earth-abundant elements, their inherent non-flammability, and the intrinsic decoupling of energy and power capacities in the flow battery design. Our group has demonstrated that calendar life, rather than cycle life, limits molecular lifetimes in AORFBs due to various molecular instabilities that lead to side reactions, thus inhibiting performance [1]. To accurately determine molecular fade rates, we utilize potentiostatic cycling to avoid artifacts caused by drifts in internal resistance and employ volumetrically unbalanced compositionally symmetric cell configurations to distinguish molecular fade from membrane crossover or the two sides drifting out of balance.We have developed a high-throughput setup for AORFBs, capable of cycling cells at elevated temperatures, providing a new dimension in the flow battery characterization space to explore multiple cell parameters simultaneously. The recent incorporation of the decay of active material into zero-dimensional cell-cycling models for AORFBs [2,3] allows for exploration of the causes of various trends seen in flow cell temporal capacity behavior. Complemented by zero-dimensional modelling, we explore temporal capacity evolution in symmetric cells driven by different capacity fade mechanisms such as active species degradation [4], self-discharge [5], and membrane crossover. Collectively, these results highlight the relevance of electrochemical techniques to understand molecular degradation in AORFBs and expedite the screening process of candidate molecules for long lifetime AORFBs, which may enable massive grid penetration of intermittent renewable energy.[1] M.-A. Goulet and M. J. Aziz, “Flow Battery Molecular Reactant Stability Determined by Symmetric Cell Cycling Methods,” Journal of The Electrochemical Society, 165, A1466 (2018).[2] S. Modak and D. G. Kwabi, “A Zero-Dimensional Model for Electrochemical Behavior and Capacity Retention in Organic Flow Cells,” Journal of the Electrochemical Society, 168, 080528 (2021).[3] B. J. Neyhouse, J. Lee, F. R. Brushett, “Connecting Material Properties and Redox Flow Cell Cycling Performance through Zero-Dimensional Models” Journal of The Electrochemical Society, 169, 090503 (2022).[4] D. G. Kwabi, Y. Ji, M. J. Aziz, “Electrolyte Lifetime in Aqueous Organic Redox Flow Batteries: A Critical Review,” Chemical Reviews, 120, 6467 (2020).[5] E. M. Fell, D. De Porcellinis, Y. Jing, V. Gutierrez-Venegas, R. G. Gordon, S. Granados-Focil, M. J. Aziz, “Long-term stability of ferri-/ferrocyanide as an electroactive component for redox flow battery applications: On the origin of apparent capacity fade,” ChemRxiv (2022). https://chemrxiv.org/engage/chemrxiv/article-details/62913087f89e5d4e6ee8828d

Development of Next-Generation Spherical Tokamak Concept. The Globus-3 Tokamak

The concept of next-generation spherical tokamak is being considered: the Globus-3 project,which, in its characteristics, is compatible with the infrastructure existing at the Ioffe Institute, but differsfrom the currently operating Globus-M2 tokamak in the stronger toroidal magnetic field (1.5–3.0 T) andincreased duration of plasma discharge. The parametric analysis data are presented that determined the preliminaryselection of the facility parameters. Three options for the electromagnetic system were considered:with the warm copper coils, with the pre-cooled copper coils and with the coils made of high-temperaturesuperconductors. For the first option, the concept for designing the electromagnetic system and vacuum vesselof the facility has been developed. The basic shot scenario with duration of up to 3 s at the field of 1.5 Tand plasma current of 0.8 MA is presented.

Detection of FOX-AmpC-β-lactamase gene and antibiogram of AmpC-beta-lactamase-producing pathogens isolated from chronic suppurative otitis media patients in Nigeria.

AmpC-producing Gram-negative bacterial (GNB) pathogens are distributed worldwide, especially in clinical settings. This study aimed to determine the antibiogram and the type of AmpC-β-lactamase gene harboured by GNB pathogens implicated in chronic suppurative otitis media (CSOM) cases. Ear swab samples (300) collected from patients with active CSOM were analysed using standard microbiological techniques. Phenotypic and molecular detection of AmpC β-lactamase production was done by cefoxitin/cloxacillin double-disk synergy test and PCR respectively. Antibiogram was determined by disk diffusion technique. Among the GNB pathogens isolated from CSOM patients, P. aeruginosa was the most predominant (36.3%); followed by K. pneumoniae (22.3%), and E. coli (13.7%). Patients with active CSOM showed increased bacteria isolation rate from bilateral ear discharges than unilateral ear discharges. E. coli and P. aeruginosa were more prevalent among patients with duration of discharge >2 weeks; recording 9.0% and 20.3% respectively. AmpC β-lactamase producers accounted for 14.0%; they were highly resistant (60%-100%) to cephalosporins, trimethoprim-sulfamethoxazole, ofloxacin, amoxicillin, and tetracycline, but very susceptible (70.4%-100%) to ciprofloxacin, imipenem, and amikacin. Multiple antibiotic resistance indices of isolates ranged from 0.7-0.8. FOX-AmpC-β-lactamase gene was detected in 3.9% of the isolates. The detection of AmpC β-lactamase-producing multidrug-resistant GNB pathogens harbouring FOX-AmpC-β-lactamase gene among patients with CSOM infections in our study is a serious public health problem which needs urgent intervention.

Ragone plots of material-based hydrogen storage systems

This paper presents an analytical assessment of the energy–power relationship for different material-based hydrogen storage systems, namely Metal Hydrides (MHs) and Liquid Organic Hydrogen Carriers (LOHCs). Storage systems are subjected to continuous flow discharge processes through suitable control systems to meet constant specific power demands of end users. By means of reasonable assumptions, analytical expressions of the time-dependent degree of hydrogenation (representing the state of charge) are obtained to find the amount of hydrogen discharged (delivered energy) as a function of flow rate (required power). The results are first presented in the form of dimensionless Ragone plots to highlight the dependence of the amount of discharged hydrogen on the required mass flow rate. Numerical examples are presented for a couple of illustrative systems. Moreover, these analytical expressions are shown to produce very similar results to those obtained with the solution of a dynamic model, including, beyond the kinetic equation, mass and energy conservation applied to the reactor. The results show a significant impact of power demand on the released hydrogen for most systems, similar to that of capacitors, due to the dependence of the rate of reaction on the degree of hydrogenation: as a consequence, the amount of energy that can be delivered to an end user decreases substantially with an increase in the required power, resulting in a poor utilisation factor. Based on these results, MHs exhibit almost first-order kinetics and can sustain efficient discharge with theoretical specific power up to 2kW/kg (rate of chemical energy delivered per unit mass of active substance), corresponding to a discharge duration of the order of 0.25h; some LOHCs are limited by second-order kinetics and the specific power should be lower than 1kW/kg, with discharge durations that must be above 2hour, to ensure effective utilisation of stored hydrogen.

Recommendations for representative sampling methodologies in ballast water: A case study from the land-based test

Accurate assessment of ballast water's community composition and organism concentrations is crucial for effective management. Yet, the lack of standardized global sampling methods presents challenges to achieving this objective. Inconsistencies hinder data comparison across regions and vessels, impeding efficient ballast water treatment and discharge regulation. This study conducted land-based tests to establish suitable methodologies. For organisms ≥50 μm and ≥10 μm to <50 μm, the recommended max flow rate is 50 L/min; for <10 μm organisms, 25 L/min is advised to prevent cell damage. Sampling should cover substantial discharge durations. To ensure representation, ≥50 μm organisms require ≥1m3, while ≥10 μm to <50 μm and <10 μm organisms need 20 L. The ultimate aim is standardized methods for assessing ballast water across regions and vessel types, facilitating effective management to curb invasive species and protect aquatic ecosystems.

Effects of freshet events on early life stages of fish and macroinvertebrates in a highly turbid estuary of Iberian Peninsula

The present study investigates effects of three different types of freshet events (varying in intensity, duration, and period of discharge) on the early life stages of fish, macroinvertebrates inhabiting in the water column, and the environmental conditions within the hiperturbid estuary of the Guadalquivir River. Freshet events compressed the salinity gradient and increased turbidity; during the most intense freshet event, the oxygen concentration also decreased. These environmental changes had significant effects on the abundance and distribution of aquatic organisms, reducing the nursery area from 40 km upstream to 20 or 10 km, depending on the freshet. Recovery of physicochemical conditions was relatively rapid (within one or two weeks) for less intense freshets, while the most intense event showed only partial recovery even one month later. Biological responses varied among species and time periods. Pelagic species (e.g., anchovies) were flushed out of the estuary. The populations of these species can show a posterior reintroduction and a recovery to levels similar to before the freshet, or a nonrecovery, probably depending on larval supplied from the offshore stock. In contrast, benthic and estuarine species (e.g., gobies, mysids), were just displaced downstream during the freshets. In the most intense freshet event, which occurred before the high recruitment period of these species (early spring), their abundances increased significantly, exceeding the levels of normal years (without freshets). This suggests that, depending on the intensity and the period in which the freshet occur, they could act as attraction signals for certain species. In general, estuarine and benthic species, such as gobies and other macroinvertebrates, coped better with freshets than pelagic marine migrant species, such as anchovies. However, the estuary and its estuarine organisms showed high resilience to environmental fluctuations.

Analytical and quantitative assessment of capital expenditures for construction of an aboveground suspended weight energy storage

The capital expenditures to energy capacity ratio (capex) stands as a key competitive metric for energy storage systems. This paper presents an evaluation of this indicator for an aboveground suspended weight energy storage system. For the first time, an analytical foundational correlation was found between capital expenditures of gravity energy storage, its energy capacity, and storage power. The correlation reveals that capex can be expressed as the sum of three components: one inversely proportional to discharge duration, another inversely proportional to the square root of energy capacity, and a constant term. By using established construction and power element prices the study demonstrates that capex can be reduced to less than 600 $/kW·h for discharge durations of 4 h or more, and can decrease to nearly 450 $/kW·h for a 10-h discharge duration. Employing the computed capex an evaluation of the total cost of ownership was conducted and juxtaposed with lithium-ion energy storage. The gains from adopting gravity technology become significant starting from the initial replacement of degraded Li-ion batteries. This scenario results in nearly a twofold savings in the ownership cost of gravity energy storage system over a 20-year operational span with further prospects for enhanced economic benefits.

New schemes for connecting oscillators as a part of plasma ignition systems for gas turbine engines

The effectiveness of new schemes for connecting of oscillators in plasma ignition systems of gas turbine engines is analyzed. The most efficient scheme for connecting an oscillator to reduce losses in the power circuit of the ignition system with an increased igniting ability of the plasmatron is determined. In the plasma torch, there are two types of discharges — continuous arc and pulsed capacitive, while the instantaneous power of a capacitive discharge of short duration is several orders of magnitude higher than the instantaneous power of the arc discharge. The dynamics of discharge processes in the oscillator is estimated. Analytical expressions are presented for the main parameters of pulsed discharges: maximum discharge current, energy and duration of discharges. Keywords: oscillator, plasmatron, plasma ignition system, electric arc. gabidullina.zg@ugatu.su