Initial Stage Of Operation Research Articles

Optimization and analysis of surface flashover triggered vacuum switch conduction delay time characteristics

The conduction delay time is one of the main technical parameters of the surface flashover triggered vacuum switch (STVS). Detailed research and optimization of conduction delay time characteristics are necessary for the development of high-performance STVS. In this paper, the conduction performance of STVS with different electrode structures and operating parameters is investigated in detail. Based on the analysis of the conduction process, the factors affecting the STVS conduction delay time are discussed. The experimental platform is built by using a detachable vacuum chamber, and the conduction delay time characteristics of STVS are compared under different electrode structures and operating parameters. This research analyzes and discusses the reasons for the influence of electrode structures and operating parameters on conduction delay time. The experimental results show that the structure with the trigger gap flashover surface parallel to the cathode surface has a better conduction delay time than the structure with both perpendicular to each other. Both reducing the trigger electrode embedment depth and extending the trigger gap flashover surface length can optimize the conduction delay time of STVS. However, increasing the trigger gap flashover surface length only reduces the conduction delay time at the initial stage of STVS operation. The shorter the main gap distance, the smaller the conduction delay time of the STVS. In addition, increasing the trigger current and operating voltage can diminish the conduction delay time of STVS.

Ice passport of a river icebreaker: winterization and reconstruction

The work develops a number of author's publications with an overview of the experience of operating icebreakers of project 1191 in ice conditions of inland and coastal sea waterways. This publication is devoted to the generalization of data from field observations and tests of the operability of ship systems, devices, deck mechanisms, equipment, shipboard spaces under prolonged exposure to negative atmospheric temperatures. It is noted that the icebreakers of the Kapitan Evdokimov type in the design did not demonstrate their reliable adaptability to long-term operation in winter. An overview of the main stages of reconstruction of the studied project to improve its operational performances is also performed. It is shown that the reconstruction measures of the initial stage of operation in order to improve the ice performances of the icebreaker cannot be considered scientifically justified and completed. At the same time, the optimization of the combination of its ice and navigation performances has not been achieved. Modernization measures of the last decade of operation are able to maintain the ice performances of the vessel, but their resource consumption must be justified.

Fimbriimonadales performed dissimilatory nitrate reduction to ammonium (DNRA) in an anammox reactor

Bacteria belonging to the order Fimbriimonadales are frequently detected in anammox reactors. However, the principal functions of these bacteria and their potential contribution to nitrogen removal remain unclear. In this study, we aimed to systematically validate the roles of Fimbriimonadales in an anammox reactor fed with synthetic wastewater. High-throughput 16S rRNA gene sequencing analysis revealed that heterotrophic denitrifying bacteria (HDB) were the most abundant bacterial group at the initial stage of reactor operation and the abundance of Fimbriimonadales members gradually increased to reach 38.8 % (day 196). At the end of reactor operation, Fimbriimonadales decreased to 0.9 % with an increase in anammox bacteria. Correlation analysis demonstrated nitrate competition between Fimbriimonadales and HDB during reactor operation. Based on the phylogenetic analysis, the Fimbriimonadales sequences acquired from the reactor were clustered into three distinct groups, which included the sequences obtained from other anammox reactors. Metagenome-assembled genome analysis of Fimbriimonadales allowed the identification of the genes narGHI and nrfAH, responsible for dissimilatory nitrate reduction to ammonium (DNRA), and nrt and nasA, responsible for nitrate and nitrite transport. In a simulation based on mass balance equations and quantified bacterial groups, the total nitrogen concentrations in the effluent were best predicted when Fimbriimonadales was assumed to perform DNRA (R2 = 0.70 and RMSE = 18.9). Moreover, mass balance analysis demonstrated the potential contribution of DNRA in enriching anammox bacteria and promoting nitrogen removal. These results prove that Fimbriimonadales compete with HDB for nitrate utilization through DNRA in the anammox reactor under non-exogenous carbon supply conditions. Overall, our findings suggest that the DNRA pathway in Fimbriimonadales could enhance anammox enrichment and nitrogen removal by providing substrates (nitrite and/or ammonium) for anammox bacteria.

Performance of vertical and horizontal treatment wetlands planted with ornamental plants in Central Chile: comparative analysis of initial operation stage for effluent reuse in agriculture.

This study comparatively evaluated effluent reuse from two TWs-a horizontal subsurface flow (HF) and a vertical subsurface flow (VF)-used for rural wastewater treatment in Central Chile during the initial operation stage. The two TWs were planted with Zantedeschia aethiopica and were operated for 10months at a pilot scale. The water quality of the influent and effluents was measured and compared with reuse regulations. The results showed similarities in the behavior of the effluents from the two TWs, presenting differences only in the chemical oxygen demand (COD) and different forms of nitrogen, suggesting the necessity of complementary treatment stages or modifications to the operation. The effluents from the HF better fulfilled the reuse standards for irrigation, as the VF faced problems associated with its size. However, a complementary disinfection system is necessary to improve pathogen removal in the effluents coming from the two TWs, especially to be reused as irrigation water for crops. Finally, this work showed the potential for applying subsurface TWs for wastewater treatment in rural areas and reusing their effluents as irrigation water, practice that can contribute to reducing the pressure on water resources in Chile, and that can be used as an example for other countries facing similar problems.

Removal of RNA viruses from swine wastewater using anaerobic membrane bioreactor: Performance and mechanisms

The effective removal of viruses from swine wastewater using anaerobic membrane bioreactor (AnMBR) is vital to ecological safety. However, most studies have focused only on disinfectants, whereas the capabilities of the treatment process have not been investigated. In this study, the performance and mechanism of an AnMBR in the removal of porcine hepatitis E virus (HEV), porcine kobuvirus (PKoV), porcine epidemic diarrhea virus (PEDV), and transmissible gastroenteritis coronavirus (TGEV) are systematically investigated. The results show that the AnMBR effectively removes the four viruses, with average removal efficiencies of 1.62, 3.05, 2.41, and 1.34 log for HEV, PKoV, PEDV and TGEV, respectively. Biomass adsorption contributes primarily to the total virus removal in the initial stage of reactor operation, with contributions to HEV and PKoV removal exceeding 71.7 % and 68.2 %, respectively. When the membrane is fouled, membrane rejection dominated virus removal. The membrane rejection contribution test shows the significant contribution of membrane pore foulants (23–76 %). Correlation analysis shows that the surface characteristics and size differences of the four viruses contribute primarily to their different effects on biomass adsorption and membrane rejection. This study provides technical guidance for viral removal during the treatment of high-concentration swine wastewater using an AnMBR.

Eliminating the Burn-in Loss of Efficiency in Organic Solar Cells by Applying Dimer Acceptors as Supramolecular Stabilizers.

The meta-stable active layer morphology of organic solar cells (OSCs) is identified as the main cause of the rapid burn-in loss of power conversion efficiency (PCE) during long-term device operation. However, effective strategies to eliminate the associated loss mechanisms from the initial stage of device operation are still lacking, especially for high-efficiency material systems. Herein, the introduction of molecularly engineered dimer acceptors with adjustable thermal transition properties into the active layer of OSCs to serve as supramolecular stabilizers for regulating the thermal transitions and optimizing the crystallization of the absorber composites is reported. By establishing intimate π-π interactions with small-molecule acceptors, these stabilizers can effectively reduce the trap-state density (Nt) in the devices to achieve excellent PCEs over 19%. More importantly, the low Nt associated with an initially optimized morphology can be maintained under external stresses to significantly reduce the PCE burn-in loss in devices. This research reveals a judicious approach to improving OPV stability by establishing a comprehensive correlation between material properties, active-layer morphology, and device performance, for developing burn-in-free OSCs.

Особенности проектирования кластеров как больших организационно-экономических систем

The need for accelerated reindustrialization of industry highlights the task of modernization based on modern principles of the procedure for designing new enterprises, holdings, clusters and other complex economic structures, united by a category of large organizational and economic systems. The problem is that if the development of a promising image of an industrial enterprise is carried out using an established technology (analysis of the initial data – development strategy development – building a business model – development of projects of production and social subsystems, as well as management subsystems – preparation of a business plan), then the procedure for designing an industrial cluster is not yet clearly regulated. Only the requirements for industrial clusters applying for state support for their development have been identified. The absence of such regulations leads to a situation in which some of the already created industrial clusters cease to exist due to miscalculations made during their formation and the organization of the initial stage of operation. The features of organizational design of industrial clusters – a promising form of regional concentration of production are consiered. The article discloses the features of industrial clusters and their differences from industrial enterprises from the point of view of design, and also proposes a procedure for performing this work, which includes an original set of actions that ensures the achievement of the goals of the participants in this association. Its specificity is associated with the cooperation of legally independent economic entities from various spheres of the economy, interested in obtaining an additional effect from the coordination of their activities in the region, on the terms of informal unification without losing the freedom to choose their areas of activity, but within the framework of coordinating the joint achievement of common goals.

Stress Prediction Model of Super-High Arch Dams during Their Initial Operation Stages

It is of great significance to identify the spatiotemporal stress distribution characteristics to ensure the safety of a super-high arch dam during the initial operation stage. Taking the 285.5 m-high Xiluodu Dam as an example, the spatiotemporal distribution characteristics were analyzed based on the five-year observation data after impoundment. Statistical and boosted-regression-tree-based prediction models for the dam stress were established. The boosted-regression-tree-based prediction model is more accurate than the statistical model. The monitoring indicators for the measuring points of focused locations were determined using the confidence interval estimation method. The results show that the dam was in a compression state, and the arching effect was obvious. The arch direction compressive stress gradually increased and stabilized, and the maximum appeared in the middle of the upstream face of the crown cantilever monolith. For the crown cantilever, the cantilever direction stress at the dam heel was significantly affected by the interior temperature recovery, and the arch direction stress in the middle of the upstream face was significantly affected by the reservoir water level. The measuring points of the focused locations with reliable observation data can be selected as a monitoring index to guide the initial operation.

Effect of natural fracture on the heat mining of enhanced geothermal system based on the thermo-hydro-mechanical coupling model

ABSTRACT Hydraulic fracture, natural fracture and fracture networks play a vital role for heat mining of Enhanced Geothermal System (EGS). In this work, a two-dimensional thermo-hydro-mechanical (THM) EGS model was proposed to investigate the effect of natural fracture on heat extraction performance. Based on the local thermal non-equilibrium theory and discrete natural fracture network, the spatial and temporal distribution of temperature, pore pressure, effective stress, rock matrix porosity and permeability are investigated. The results show that the natural fracture has a significant negative effect on the production temperature. After the 40-year prediction, the production temperature of the base model is 45.5°C lower than that of the without natural fracture model. In the initial operation stage, the low-temperature region is mainly distributed in the region of artificial fracture and injection well, then it expands significantly to the natural fracture due to the stress redistribution. The key parameters of quantity and orientation of natural fracture can lead to a decline in production temperature and earlier thermal breakthroughs within the thermal reservoir.

Open-Circuit-Voltage Improvement Mechanism of Perovskite Solar Cells Revealed by Operando Spin Observation.

Organic-inorganic hybrid perovskite solar cells have attracted much attention as important next-generation solar cells. Their solar cell performance is known to change during operation, but the root cause of the instability remains unclear. This report describes an investigation using electron spin resonance (ESR) to evaluate an improvement mechanism for the open-circuit voltage, VOC, of inverted perovskite solar cells at the initial stage of device operation. The ESR study revealed electron transfer at the interface from the perovskite layer to the hole-transport layer not only under dark conditions but also under light irradiation, where electrons are subsequently trapped in the hole-transport layer. An electron barrier is enhanced at the perovskite/hole-transport-layer interface, improving field-effect passivation at the interface. Thereby, the interface recombination velocity is reduced, and thus the VOC improves. These findings are crucially important for elucidating the mechanisms of device performance changes under operation. They reveal a relation between charge transfer and performance improvement, which is valuable for the further development of efficient perovskite solar cells.

Effect of Fe(II) on manganese removal in biofilters: Microbial community, formation of manganese oxide and related mechanisms

In this study, different concentrations of Fe(II) (0, 1.00, 7.00 mg/L) were introduced to investigate the effect on the removal of Mn(II) in the biofilter. Fe(II) significantly inhibited the removal of Mn and prolonged the start-up of biofilters, the start-up periods for the biofilters with different Fe(II) concentrations (0, 1.00 and 7.00 mg/L) were 24, 30 and 46 days, respectively. The study showed that Fe(II) and the Fe(III) oxyhydroxides generated from Fe(II) oxidation inhibited the removal of Mn(II) by affecting the proliferation of manganese-oxidizing bacteria (MnOB) and the activity of manganese oxides (MnOx) in the biofilter. On day 20, the total MnOB genera proportions were 13.44 %, 13.35 % and 20.09 % with different Fe(II) concentrations (0, 1.00, 7.00 mg/L), respectively. The addition of Fe(II) significantly impeded the proliferation of Pseudomonas, Acinetobacter and Arthrobacter, but enhanced the proliferation of Hyphomicrobium and Sphingopyxis. On day 60, the abundance of total MnOB was reduced obviously in three biofilters (6.95 %, 6.44 % and 9.76 %). This indicated that the biological oxidation of Mn dominates during the initial operation stage of the filter layer, while the chemical auto-catalytic oxidation of active MnOx dominates in the later stages. The contribution of Mn removal by biological oxidation was positively correlated with the abundance of MnOB, and batch experiments confirmed this conclusion. Moreover, the addition of Fe(II) reduced MnOx activity by suppressing the production of high-reactivity intermediate-Mn(III), and Fe(III) oxyhydroxides hindered the formation of mature MnOx films on the surface of the filter media.

Adaptive Asymptotic Tracking Control for Flexible-Joint Robots With Prescribed Performance: Design and Experiments

This study reports the adaptive asymptotic tracking control problem for flexible-joint (FJ) robot systems, the output tracking error can be kept within the prescribed range in the initial stage of system operation, as time approaches infinity, the asymptotic tracking result can be obtained. The prescribed performance function and the positive integrable time-varying function are introduced simultaneously in the control design of FJ robot systems for the first time. The control scheme is designed under the frame of the adaptive backstepping method and command filtered technique, which successfully avoids the problem of complexity explosion. The radial basis function neural networks are used to deal with unknown uncertainties and the adaptive laws are designed to approximate the norms of weight vectors and approximation errors. Finally, the feasibility of the proposed scheme is proved by the simulation and the experiment of the 2-link FJ robot on the Quanser platform.

A novel CCHP system based on a closed PEMEC-PEMFC loop with water self-supply

Targeting the shortcomings of oxygen waste and reactant supplement of electrolyzer, this paper proposes a novel combined cooling, heating and power (CCHP) system based on proton exchange membrane electrolysis cell (PEMEC) and H2/O2 proton exchange membrane fuel cell (PEMFC) with water self-supply. In this system, H2/O2 PEMFC adopts a dead-ended anode and cathode operation mode to achieve 100 % hydrogen and oxygen utilization and water recovery. For the application scenario of a household in Shanghai, China, the performance of the CCHP system in summer and winter is investigated. When the system gives priority to meeting the electric and cooling load, there will be insufficient heat at the initial stage of operation. The pre-operation model can realize the hourly matching of residential electric, heating and cooling loads. After one day of operation in summer and winter, there are 19.1 kWh and 45.5 kWh electricity surplus, 7.27 × 106 kJ and 1.97 × 106 kJ heat surplus, 1200 mol and 300 mol hydrogen surplus, respectively. Moreover, the estimated payback period for this system is 7.6 years, which will be significantly shortened with the decrease of the cost of photovoltaic panels and PEMEC.

Impact study of beam losses in TRIUMF’s BL4N proton cave and ARIEL tunnel

As part of the ARIEL project, currently under construction at TRIUMF, a new proton beam line will be installed to transport up to 100 µA of nominal beam energy 480 MeV protons from the main cyclotron extraction port to an isotope separator on-line (ISOL) proton target station. This new beam line, approximately 80 m long, designated beam line 4-North (BL4N), will connect the cyclotron to the ARIEL facility via a tunnel. The proton beam line is designed for beam losses lower than 1 nAm−1 and will feature a collimator to remove the beam halo produced by large-angle scattering in the cyclotron extraction foil.The tunnel will be shared with an electron beam line with its own specific requirements for beam loss mitigation and machine protection, leading to another ISOL electron target station. The electron beam is generated by an e-linac with capacity for 500 kW beam power operation, but is ultimately expected to operate at 100 kW with losses not exceeding 20 nAm−1. After an initial stage of operation at 25 MeV the beam energy will be upgraded to 50 MeV.In this work, the effect of the beam losses, both chronic and catastrophic, in the tunnel and adjacent areas were studied. The FLUKA particle transport and interaction code was employed to estimate the impact of the combined proton and electron beam losses to the shielding, including as well the reflection of radiation from the target stations into the tunnel during ARIEL operation. This analysis resulted into a better assessment of the damage to equipment in the tunnel and the impact on maintenance due to activation of elements of the beam line. Maximum credible accidental scenarios were also detailed to validate the shielding configuration and the safety systems location.

The concept of sustainable transportation and unmanned railway technologies: the EAEU experience

The article attempts to critically assess the current regulatory framework in the field of unmanned technologies through the prism of the concept of sustainable transportation in the EAEU. The main trends in the development of unmanned technologies in transportation are identified. Using the example of the Russian railway transportation, the key technical and technological aspects of the operation of unmanned systems, which need a primary mechanism of regulation, are shown. The study shows that the effectiveness of high-level automation technologies directly depends on adequate normative and technical regulation and legal basis for ensuring safety issues and regulating responsibility at the interstate level. The authors consider it advisable to apply a test procedure for the use of unmanned technologies at the initial stage of operation, as well as to create “regulatory sandboxes” before the mass operation of unmanned vehicles. The development of international legal regulation of unmanned transport will become a driver for the realization of Russia’s transit potential, especially in the context of de-globalization trends in the world economy and anti-Russian sanctions.

Effects of Viscosity on Submerged Membrane Microfiltration Systems.

Submerged microfiltration has a wide range of applications in water and wastewater treatment. Membrane fouling is a major problem, resulting in a severe decline in flux, high energy consumption and frequent membrane cleaning and replacement. The effect of viscosity was not previously studied under controlled conditions to relate it to the air scour. Hence, this study investigated the effect of viscosity on membrane fouling during the operation of submerged membrane microfiltration by adding predetermined amounts of glycerol to a kaolin clay suspension. The addition of glycerol increased the viscosity (from 0.001 to 0.003 Pa·s), resulting in a 3-fold higher transmembrane pressure (TMP) development. An increased airflow (air scour) rate by 3 fold (from 0.6 m3/m2/h to 1.8 m3/m2/h), reduced TMP development by 65%. Membrane fouling quickly developed during the initial stage of microfiltration operation. Therefore, special precautions to control fouling during the early stages of filtration could significantly enhance the operation of the microfilter. Higher airflow caused a reduction in average specific cake resistance, whereas higher viscosity increased this value.

Prediction and analysis of water rights trading volume: Based on the water rights trading in Inner Mongolia, China

Water rights trading volume (WRTV) is an integral part of an effective transaction. At present, in China, WRTV is mostly based on the water demand of the transferee, not the transferor. Some transactions last for a long time, yet lack proper measures to adjust trading volume, making theoretical and quantitative studies on WRTV necessary and essential. Therefore, based on the theory of property rights, this study first analyzed the concept of WRTV, and proposed that WRTV must consider the tradable water volume (TWV) of the transaction parties. For that, this paper divided water rights trading into two stages: initial stage and operation stage, to analyze how to measure WRTV in different stages. Second, currently, industry or sector is a major player of water rights trading. TWV of industry is, hence, the difference between the initial water rights volume (IWRV) and water demand of industry, significant for calculating WRTV in different stages. For that, this study employed the ratio method to calculate the IWRV of industry, and the Grey Model—GM (1,1) to predict the water demand of industry. Last, this paper carried out a case study on the inter-league and inter-city water rights trading between Bayannur city and Ordos city in Inner Mongolia, China. Results show that the TWV of industry of Bayannur and Ordos in 2030 are – 904.966 million m3 and − 87.135 million m3 respectively, implying insufficient TWV for the transferee, which may lead to transaction breakdown. The theory and calculation method of WRTV proposed in this study lay a theoretical foundation for WRTV measurement, and can help facilitate the orderly development of water rights trading in China.

Development of a two color interferometer on a field-reversed configuration device

Two color interferometer adopting short wavelength lasers is one of the most reliable methods to measure the electron density in high density fusion devices, which is immune to mechanical vibration and fringe jump error by using two lasers of different wavelength. Considering the anticipant line-integral electron density of 1020∼1021 m−2, the initial plasma duration of tens of μs, and the expected rotational instability on the order of several μs at the HUST-FRC (HFRC), a single chord two color (CO2/HeNe, 10.6 μm/0.633 μm) heterodyne system is installed in the initial operation stage of HFRC. The modulation frequency is 40 MHz, which is generated by acousto-optic modulator (AOM) and benefits for the future physical research. The experimental results show that the phase noise of the two color interferometer system is within 1.7° and the residual error is less than 1 × 1018 m−2. Based on the results of the single-channel interferometric system, a multi-channel system can be expected in the future.

Performance Evaluation of Cross-Linked Polyethylene Insulation of Operating 110 kV Power Cables.

The ageing characteristic of XLPE insulation of operating a 110 kV power cable with different service time is studied in this paper. The microscopic morphology of XLPE films from different cables were characterized by using Differential Scanning Calorimetry (DSC), X-ray Diffraction method (XRD), and Fourier Transform Infrared Spectroscopy (FTIR) methods, and the dielectric, mechanical, and electrical properties of XLPE were also measured. The relationship of several typical property parameters with the cable service time were established, and the ageing mechanism of XLPE insulation of the operating cable was also analyzed. It was found that XLPE insulation would endure a recrystallization process in the initial operation stage during which the microscopic morphology would become more perfect with higher crystallinity and denser crystal structure. Then, the thermal oxidation would dominate the ageing process of XLPE with the molecular chains broken and more micromolecular products generated after the cable had operated for more than 10–15 years. The AC breakdown strength decreases with the increase of cable service time, with lower decreasing rate in the initial operation stage and a larger rate after 10–15 years. The Pearson correlation coefficient between the cable service time with the characteristic parameters were calculated, and some of them were found to be effective to be used as indicators for operation state detection of operating power cables.

Impact of Car Traffic on Metal Accumulation in Soils and Plants Growing Close to a Motorway (Eastern Slovakia).

The paper evaluates the impact of car transport on the distribution and accumulation of Zn, Cu, Pb and Cd in soils, as well as in the vegetation near a newly built R4 motorway Košice-Milhosť (Slovakia). Samples were taken from surface humus layer (litter) and 0–5, 10–20 and 20–30 cm mineral layers of Cambisol and Luvisol, as well as from assimilatory organs of Fraxinus excelsior, Quercus cerris, Quercus rubra, Negundo aceroides and Anthriscus sylvestris growing in the segments of geobiocoenosis Querci-Fageta Typica. The concentrations of total Zn and Cu were determined using SensAA AAS and the total concentrations of Cd and Pb using an instrument iCE 3000 Series AAS-F. Contamination factor (CF) values showed that surface humus layer of both soil units is moderately contaminated with Zn (1 ≤ CF ˂ 3), low contaminated with Cu (CF ˂ 1) and considerably contaminated with Pb and Cd (3 ≤ CF ˂ 6). Contamination of the surface humus layer of Luvisol with Pb is very high (CF > 6), while in the case of mineral layers with Zn and Cu it is low (CF ˂ 1). The mineral layers of Luvisol are moderately contaminated with Pb and Cd (1 ≤ CF ˂ 3) and Cambisol layers with Zn, Cu, Pb and Cd. For the group of 5 tested plants, higher values of toxic elements in the leaves were observed on Luvisol compared to Cambisol. However, only Cu conconcentrations in Luvisol significantly correlated with Cu concentrations in plants (r > 0.4 or r < 0.6). The same can be said for Zn concentrations in Cambisol (r > 0.8). The best indicator of the environment polluted by car traffic appears to be A. sylvestris. Transfer coefficients (TC ˃ 1) revealed that this species concentrated the most Zn and Cu on Luvisol and close to 1 are also the TC values found for Cu in F. excelsior and Q. cerris leaves taken on Luvisol. Lead is accumulated most efficiently in N. aceroides leaves and Cd in A. sylvestris leaves regardless of soil unit. Compared to background values, the total concentrations of trace elements in soils and plants were significantly higher and point to the pollution of forest ecosystems already in the initial stage of motorway operation.