Continuous Operation Of System Research Articles

Protection of intellectual property rights during martial law

The article is devoted to the protection of intellectual property rights under martial law imposed in connection with the aggression of the Russian Federation. The author notes that even in the most difficult periods, intellectual property remains strategically important for the development of a country. It is worth noting that the protection of intellectual property rights is becoming an extremely important task which requires careful analysis and effective measures. It is indicated that preventing violations and ensuring stability in this area is of great importance for preserving the country’s economic potential. Martial law has become a time of increased risk to intellectual property due to a number of factors, such as an increase in the number of conflicts, unpredictability of the political situation and changes in governance. The article emphasises that Ukrpatent, which performs the powers of the National Intellectual Property Authority in the field of intellectual property, continues to work in difficult conditions. At the same time, it ensures the necessary functions and continuous operation of the state system of intellectual property legal protection. It is interesting to note that starting from 8 November 2022, the Ukrainian National Office of Intellectual Property and Innovation has been performing the functions of the National Intellectual Property Authority. The activities of the Ukrainian National Office of Intellectual Property and Innovation are crucial for stimulating innovation and development in the country, especially in the difficult conditions of martial law. Its functions include registration of IP rights (patents, copyrights, and trademarks), maintenance of state registers, support of collegial bodies, international cooperation, information and publishing activities, provision of services and consultations, and certification of patent attorneys. It is established that in Ukraine, during martial law, the legislative activity in the field of intellectual property continues and the processes of European integration in the field of intellectual property are being intensified by improving the regulatory framework in accordance with international norms and standards. This demonstrates the country’s ability to ensure the functioning and development of the legal system even in extremely difficult conditions. The article also examines the latest changes in the legislation relating to intellectual property in the context of martial law, which demonstrates the continued and responsible legislative activity in this area, even in the most difficult times for the country.

APPROACH TO DETECTION OF ANOMALOUS NETWORK TRAFFIC USING LOF AND HBOS ALGORITHMS

The article is devoted to the problem of detecting anomalies in modern computer networks, which is one of the main threats to cyber security. With the development of Internet technologies, the number of devices and the volume of network traffic are constantly increasing, which leads to an increase in the risk of various cyber threats, such as DDoS attacks, zero-day attacks, and exploitation of protocol vulnerabilities. Abnormal network traffic can result from malicious activity and technical malfunctions, such as configuration errors or hardware failures. Specialised algorithms and methods of analysing large volumes of data are used to detect such threats. The paper considers the main methods of detecting anomalies in network traffic, including classical approaches and modern deep and machine learning methods. Special attention is paid to the efficiency of using methods based on convolutional neural networks, long-term memory and their combinations to detect anomalies. An analysis of the disadvantages and advantages of various approaches to detecting anomalous traffic, such as high computational requirements and the complexity of setting up models, is performed. Still, their effectiveness in analysing large volumes of data is noted. One of the main methods used for anomaly analysis is the local outlier algorithm, which compares the density of objects with their neighbours, allowing for the detection of anomalies in regional segments of the data. Another method is histogram-based outlier estimation, which is faster and more efficient using one-dimensional histograms for each variable. The work also explores the application of unsupervised machine learning methods, which allows for analysing network traffic in real time without the need for prior labelling of data. The article also considers the prospects of further testing the proposed methods in real networks. The combined use of LOF and HBOS balances anomaly detection accuracy and data processing speed, essential to ensure continuous system operation in high-load networks. The implementation of similar solutions in actual conditions requires further research, particularly regarding optimising the use of computing resources and adapting methods to the specific conditions of the network environment. Thus, the paper presents a thorough analysis of modern approaches to detecting anomalies in network traffic and substantiates the feasibility of their application in actual conditions to increase the effectiveness of cyber security.

Technical and economic simulation of a hybrid renewable energy power system design for industrial application

Countries in Africa rank the highest in low energy accessibility and air pollution globally. Presenting the urgent need to explore renewable energy sources to tackle the power challenge and reduce the carbon footprint for a greener atmosphere. A novel hybrid wind and solar renewable energy power system (HREPS) coupled to a battery that is capable of powering industrial appliances in the Basse district of The Gambia has been proposed. The HREPS size was estimated automatically with the PVsyst software taking into account the PV power and battery capacity based on the load profile and loss of load probability, with all the necessary meteorological, technical, and economic factors. The optimal size was possible with 20 photovoltaic modules (250 W) and 1 Wind generator (1 KW) compatible with the annual load requirement of about 2555 MWh. These results suggested that the HREPS is reliable for the user’s load demand in all the tested meteorological conditions of the study area. When the HREPS is linked to any other renewable source, it shows the potential of gaining about 8395 kWh annually in the battery. The continuous operation of the hybrid system for 21 years presents a net gain of > 400% for the standalone systems with a projected gain of > 600% when linked to a small smart grid system. Since high taxes may scuttle these gains, it is recommended that the Government encourage investment in renewable energy power systems by subsidizing the taxes on the purchase of items to make them more affordable.

Engineering cellulose aerogel composites for mercury ion sequestration and aquatic real time monitoring based on the immobilization of metal-organic frameworks

Industrial wastewater effluents containing elevated levels of mercury are a significant menace to both the ecosystem and human health. Despite the advent of metal-organic frameworks (MOFs) as promising adsorbents, their application in treatment of industrial wastewater has been impeded by the challenges associated with handling their powdered form. In this work, we introduce a straightforward method for fabricating MOF composite cellulose aerogels (5MM-101@CA). The resulting adsorbent showed a high adsorption capacity of 409.84 mg/g for Hg (II), with over 75 % removal efficiency maintained after five consecutive adsorption-desorption cycles. Furthermore, the material exhibited high sensitivity for the real-time detection of Hg (II), with a detection limit as low as 6.89×10−8 M. The adsorbent also showed remarkable fluorescence stability for up to a week, indicative of its excellent optical performance. Dynamic adsorption demonstrated the adsorbent's ability to sustain continuous and stable system operation without compromising adsorption efficiency. These findings underscore the effectiveness of post-synthetic modification (PSM) technology in enhancing the performance of MOFs, while highlighting the utility of low-cost cellulose as an effective carrier. Thus, the composite material developed in this work is promising as it not only maximizes the adsorption capabilities of MOFs but also circumvents the risk of secondary pollution.

Enhancement of Water Productivity and Energy Efficiency in Sorption-based Atmospheric Water Harvesting Systems: From Material, Component to System Level.

To address the increasingly serious water scarcity across the world, sorption-based atmospheric water harvesting (SAWH) continues to attract attention among various water production methods, due to it being less dependent on climatic and geographical conditions. Water productivity and energy efficiency are the two most important evaluation indicators. Therefore, this review aims to comprehensively and systematically summarize and discuss the water productivity and energy efficiency enhancement methods for SAWH systems based on three levels, from material to component to system. First, the material level covers the characteristics, categories, and mechanisms of different sorbents. Second, the component level focuses on the sorbent bed, regeneration energy, and condenser. Third, the system level encompasses the system design, operation, and synergetic effect generation with other mechanisms. Specifically, the key and promising improvement methods are: synthesizing composite sorbents with high water uptake, fast sorption kinetics, and low regeneration energy (material level); improving thermal insulation between the sorbent bed and condenser, utilizing renewable energy or electrical heating for desorption and multistage design (component level); achieving continuous system operation with a desired number of sorbent beds or rotational structure, and integrating with Peltier cooling or passive radiative cooling technologies (system level). In addition, applications and challenges of SAWH systems are explored, followed by potential outlooks and future perspectives. Overall, it is expected that this review article can provide promising directions and guidelines for the design and operation of SAWH systems with the aim of achieving high water productivity and energy efficiency.

Assessment of the safe operation of main gas pipelines

This work is devoted to improving the safety and reliability of the operation of main gas pipelines through a detailed assessment of their condition using the developed probabilistic deterministic model. The model allows you to calculate the probability of trouble-free operation of pipelines, which is critically important both at the design stage and during operation. The article analyzes defects that occur when using gas pipelines, including corrosion of pipe metal, which is one of the main causes of accidents, as shown by the example of technical investigation of incidents on Kazakh gas pipelines. Studies conducted by domestic companies have revealed that corrosion cracking due to the high corrosion activity of soils seriously threatens the safety of gas pipelines in Kazakhstan. The acceleration of the cracking process exacerbates the problem, making these damages especially dangerous for the structural integrity of metal pipelines and, accordingly, pose a significant challenge to the global gas transportation system. To combat these problems, the use of modern technologies is proposed, including robotic in-line diagnostics and remote methods for assessing the condition of gas pipelines, such as unmanned systems and aerospace research. These methods make it possible not only to predict corrosion and other types of damage on all types of gas pipelines, but also to detect cracks, ruptures and areas of gas leaks. In addition, they contribute to monitoring the environmental situation along the gas pipelines and provide complete and reliable information about the condition of not only control, but also all sections of the route. The application of these advanced diagnostic methods ensures the continuous and safe operation of the gas transmission system, ensuring a stable supply of natural gas to consumers, thereby increasing the overall safety and efficiency of gas supply.

Fresh water production via atmospheric water harvesting using solar energy for green hydrogen production

Abstract Solar energy is used to drive an atmospheric water harvesting unit to produce fresh water needed for the electrolysis process to produce hydrogen, as well as to drive the electrolyzer. So, the system can be considered as a solar powered hybrid system for fresh water harvesting and green hydrogen production implementing the electrolysis concept. Implementation of the system specially in arid regions with high levels of water scarcity and high relative humidity levels helps in achieving SDGs 3, 7, 9, and 13 progressively, improving health and wellbeing, reducing water scarcity, using clean renewable energy, and limiting climate change. The system is proposed and investigated for the production of both fresh and clean water and green hydrogen gas. To improve the productivity of the overall system, performance enhancement of the atmospheric water harvesting subsystem is experimentally investigated to assure the reliability and continuous operation of the overall green hydrogen hybrid system. It was investigated in summer and winter using different number of porous sheet metals with the silica gel bed. The results show that the productivity of the atmospheric water harvesting system can be increased by a minimum of 6% with one mesh metal sheet and 30% with two meshes, and increases by a maxinmum of 60% with one mech and 260% with two meches.

Carbon capture via electrochemically mediated alkaline absorption: Lab-scale continuous operation

Energy-efficient capture technologies need to be deployed by 2050 to abate global warming caused by excessive carbon dioxide (CO2) emissions. CO2 capture using alkaline solutions and absorbent regeneration mediated through bipolar membrane electrodialysis (BMED) have been tested previously as a standalone technology. However, the continuous operation of an integrated system remains largely unclear. Here, a bench-scale study was conducted using an integrated prototype to analyze the performance of CO2 capture and electrochemical regeneration using potassium hydroxide (KOH) aqueous solution. A wide range of current densities from 150 to 1000 A/m2 was applied to demonstrate the continuous operation of the CO2 capture system emphasizing the stability in attainable high rich carbon loading and CO2 desorption. The electrochemical regeneration module achieved CO2 desorption efficiency of 70% and absorbent recovery up to 89% under industrial relevant current densities of 500–1000 A/m2. The absorbent recovery has been identified to be a result of the combined effect of load ratio and rich carbon loading. The observed inefficient CO2 separation indicates significant potential to enhance energy efficiency. These results represent a pivotal step forward in electrochemically mediated CO2 capture technology, with promising potential for rapid industrial scale-up in the near future.

Finite Element Analysis of Flow-Electrode Capacitive Deionization

As access to freshwater diminishes due to climate change and population growth, drought-stricken regions across the globe continue to turn to groundwater and desalination. A largely untapped water resource in many parts of the world is brackish water - defined as water with total dissolved solids (TDS) in the range of 500 ppm to 10,000 ppm. Flow Capacitive Deionization (FCDI) is an electrochemical ion removal technology that is well-suited for the continuous desalination of brackish waters. Traditional Capacitive Deionization (CDI) consists of two fixed capacitive electrodes which are charged and discharged cyclically to capture ions from the solution being treated, and then regenerated to create a waste brine stream. During FCDI operation however, an applied potential drives ions out of a center water channel, typically through a pair of cation and anion exchange membranes (CEM/AEM), and into two flowing capacitive slurry electrodes (Figure 1). Because the electrodes are mobile, they can be moved into an adjacent cell for regeneration, thus enabling continuous operation of the desalination system without cyclical charge/discharge. The cathode and anode slurries typically consist of activated carbon suspended in a salt solution.Because the electrodes are flowing in FCDI, models describing this system must translate the Eulerian derivative to describe transient capacitive charge/discharge to a Lagrangian material derivative following the electrode material flowing through space. A flowing capacitive electrode is a significantly more complex system than a stationary porous and capacitive electrode matrix, incorporating the fluid dynamics of the slurries, ion transport within the slurry’s electrolyte medium, etc. Despite nearly a decade of research into FCDI, few researchers have probed the transient and spatially dependent mechanisms of ion transport and electro-adsoprtion within flow electrodes. While the overall electrodialytic contributions to ion capture within FCDI systems have been studied (1,2), the mechanism of competition between the electrodialysis and capacitive ion capture within the flow electrodes remains somewhat elusive. Additional analysis of the ion transport phenomena within these flow electrodes could bring forth insights into optimal design of FCDI devices and/or electrode formulations.In this study, an existing 2-dimensional mathematical model (3,4) for electrochemical flow capacitors is adapted to FCDI and solved via finite element analysis in COMSOL Multiphysics. Transport equations describing the advection of overpotential along with the flowing electrode are coupled with the Nernst-Planck equations which govern ion transport within the CEM/AEM, center water channel, and slurry electrolyte medium. This study investigates the effect of slurry flow velocity and sodium chloride concentration in the influent water on electrical potential profiles within an FCDI cell, and illustrates the active regions of capacitive electro-adsorption through the depth of the flow channel. Models of electrodialysis and FCDI are compared to understand the fundamental differences in driving forces for ion removal between the two technologies. The model shows agreement with experimental data through prediction of salt adsorption rate trends (mmol NaCl m-2 s-1) vs. influent sodium chloride concentrations. Through this analysis, it is shown that this model may serve as a valuable groundwork for expansion of FCDI modeling capabilities to include three dimensional cell geometries and subsequent optimization of operational parameters and cell dimensions. P. Nativ, Y. Badash, and Y. Gendel, Electrochem. Commun., 76, 24–28 (2017). J. Ma, C. He, C. Zhang, and T. D. Waite, Water Res., 144, 296–303 (2018). N. C. Hoyt, J. S. Wainright, and R. F. Savinell, J. Electrochem. Soc., 152, A652–A657 (2015). N. C. Hoyt, R. F. Savinell, and J. S. Wainright, Chem. Eng. Sci., 144, 288–297(2016). Figure 1

A novel hybrid-fuzzy logic based UVC technique for solar-PV/grid integrated water-pumping system

The continual depletion of fossil fuels and increased green-house emissions are persuading the consumers to install micro-renewable energy sources-based water pumping system. Among numerous energy sources, the solar-PV plays a significant role in water pumping application due to its virtuous, environment friendly, noise-free and abundant nature, so on. Along with solar-PV, the grid integrated system enables the continuous operation of water pumping system during varying temperature and irradiance conditions, and also delivers available solar-PV energy to grid during non-functional of pumping system. The above operations are carried by using bidirectional inverter which is controlled by using unit-vector control (UVC) technique. It consists of proportional-integral controller, which is not suited for regulation of DC-link voltage at desired level because of improper selection of gain values. In this work, an intelligent hybrid-fuzzy logic based UVC technique evidences the intelligent knowledge base for better regulation of DC-link voltage and power-flow of bidirectional inverter. The performance and operation of proposed hybrid-fuzzy logic control UVC technique for solar-PV/Grid integrated water-pumping system is evaluated under various operating cases by using MATLAB/Simulink tool; simulated results are conferred with superlative comparisons.

Treatment of high-strength wastewater with coupled flocculation and membrane filtration prior to ammoniacal nitrogen enrichment by osmotically assisted reverse osmosis

Membrane scaling poses significant challenges in membrane processes involving high-strength feed streams. In this work, a treatment of high-strength NH4-N-containing wastewater comprising the flocculation of Ca and Si and membrane filtration is introduced. The pretreated wastewater underwent further dewatering and enrichment through a hybrid osmotically assisted reverse osmosis and reverse osmosis (OARO-RO) process. During the treatment, the molar ratio of the acid flocculant FeCl3 to Si was adjusted, as well as the molar ratio of the alkaline flocculant Na2CO3 to Ca. Furthermore, the molar ratio of FeCl3 and Na2CO3, as well as the order of flocculant addition, was optimized in terms of Si and Ca removal and treated water pH necessary for NH4-N recovery. Membrane filtration was afterwards conducted to remove the floc from the treated wastewater prior to the OARO-RO operation. The optimized pretreatment process resulted in removal of approximately 70 % Si and 60 % Ca content in the wastewater. OARO-RO was operated using pretreated wastewater to demonstrate the effectiveness of the coupled flocculation and filtration pretreatment in enrichment of highly concentrated feed streams. Two scenarios of OARO-RO operation were performed by manipulating the operational parameters. Successful continuous operation of the OARO-RO system was observed despite the operational conditions and the wastewater was enriched more than 11 times, without operation interruption and occurrence of scaling, resulting in an enriched wastewater containing around 50,000 ppm T-N. Therefore, coupled flocculation and membrane filtration treatment process is effective to mitigate membrane scaling when concentrating highly concentrated feed streams.

Continuous CO synthesis from ambient air by integrating direct air capture and direct carbonate reduction using an alkaline CO2-absorbing electrolyte operating at room temperature

We constructed an integrated system comprising direct air capture (DAC) and direct carbonate reduction (DCR) to facilitate the industrial implementation of negative CO2 emissions. The DAC-DCR system demonstrated continuous CO synthesis from ambient air at room temperature, in contrast to conventional methods, including high-temperature processes and previously reported a batch-type method that connect DAC and DCR. The CO2-absorbing electrolyte, a K2CO3-KHCO3 aqueous solution, is circulated between the DAC and DCR subsystems. The CO2 captured from the air with the CO2-absorbing electrolyte is converted to carbonate in the DAC; subsequently, the carbonate is electrochemically reduced to CO in the DCR. This system monitored the CO2 capture rate, carbonate reduction rate, and pH of the CO2-absorbing electrolyte in real time. Controlling the carbonate reduction rate by adjusting the DCR reactor current enabled the balancing of carbon capture and carbonate reduction rates. Consequently, stable and continuous operation of a DAC-DCR system was achieved for over one hour for the first time. The DAC-DCR is more suitable for combination with intermittent renewable electricity, including photovoltaic and wind electricity, than the previous methods because all the processes in the system work at room temperature. Thus, the present proof-of-concept study is an important step toward the widespread use of DAC.

Safety Analysis of the Hydrolysis Reactor in the Cu-Cl Thermochemical Hydrogen Production Cycle—Part 1: Methodology and Selected Top Events

In this paper, IEC 61511 was used to evaluate the hazards and risks associated with the continuous operation of the hydrolysis reactor system in the copper-chlorine thermochemical hydrogen production cycle, with a specific focus on the application of automated active safety systems and safety integrated systems. The analysis presented herein was performed using a speculative but representative hydrolysis piping and instrumentation diagram (P&ID) for the hydrolysis reaction, which was based on currently published systems as well as experience with experimental hydrolysis reactors. This analysis was then used to inform the design of a set of automated safety systems that provide the redundant operation of critical devices and can bring the hydrolysis to a safe shutdown state if needed.

Analysis and optimization of a medium-depth ground source heat pump heating systems with heat storage and borehole heat exchangers

The medium-depth ground source heat pump (MD-GSHP) heating technology is considered a clean energy solution with the potential to mitigate air pollution issues attributed to winter heating in northern China. However, it currently suffers from problems such as a mismatch between heat supply and demand and a lack of optimal operation. To overcome these limitations, this study focuses on a 3000 m2 residential building in Xi’an and implements two configurations: coupling MD-GSHP heating systems with heat storage tank and shallow borehole heat exchanger (BHE). Additionally, an optimization strategy based on the improved particle swarm algorithm is proposed, integrating chaos optimization and dynamic parameters. Finally, noteworthy outcomes were revealed by optimizing the MD-GSHP heating systems under different objective functions. In system coupled with shallow BHE, the variation trend of flow in the medium-depth BHE was similar to that of heating load when the heating cost was taken as the objective function. After the optimization, heating cost reduced by 10.02%, while system coefficient of performance (COP) and medium-depth geothermal utilization coefficient increased by 10.43% and 2.00%, respectively. For system coupled with heat storage tank, the optimized flow exhibited a generally decreasing-increasing-decreasing trend, with the peak preceding the heating load curve. This resulted in a 12.82% reduction in heating cost, along with increases of 10.35% and 1.96% in system COP and the medium-depth geothermal utilization coefficient, respectively. Comprehensive consideration of heating cost and system COP suggested a favorable weight of 2.8 for continuous system operation. In conclusion, when prioritizing heating cost, the system coupled with heat storage tank yields greater economic benefits compared to the system coupled with shallow BHE. The findings of this study can provide a guidance for the applications of the MD-GSHP heating technology.

Research on Reliability of Distribution Network Power Engineering Technology

With the progress of society, electric power resources have become an indispensable part of people's production and life. The power system composed of four parts, namely, power plant, transmission network, distribution network and users, is an important part of China's power grid, supporting the transmission and use functions of China's power grid. Therefore, ensuring the stable and continuous operation of the power system helps to build a strong transmission network in China, improve the transmission efficiency and efficiency of the power grid, and further improve the maturity of the power engineering technology of the distribution network. Therefore, this paper studies the reliability of distribution network power engineering technology.

Generating a Sustained Oxygen-Stable Atomic Concentration in a High-Temperature Gas Effect Investigation.

Modulated laser absorption spectroscopy is an ideal technique for evaluating flow-field parameters and determining flow-field quality by measuring the atoms dissociated in high-temperature environments. However, to obtain the absolute number density of atoms in the flow field, it is necessary to compare the measured modulated absorption spectroscopy signal with a known atomic concentration and establish a quantitative relationship through concentration calibration. Nevertheless, it remains a challenging task to prepare transient atomic samples with known concentrations that meet the calibration requirements. This study utilized the alternating-current glow discharge technique to dissociate oxygen in the air flow, resulting in the continuous generation of oxygen atoms. The absolute number densities of the generated oxygen atoms were determined by measuring the direct absorption spectra of centered on 777 nm for oxygen atoms. The number densities of the generated atoms were finely tuned by adjusting the discharge parameters. Throughout the 120-min continuous operation of the discharge system, the concentration of excited-state oxygen atoms remained stable within the range of (2.51 ± 0.02) × 108 cm-3, demonstrating the remarkable stability of the transient atomic concentration generated by the glow discharge plasma. This observation suggests that the generated atoms can be utilized as a standardized atomic sample of known concentration for absolute concentration calibration purposes.

Flexible reconfigurable entanglement-based quantum key distribution network

AbstractRecently, we implemented a basic star-shaped entanglement-based quantum key distribution network without trusted nodes. It enables simultaneous pairwise exchange of quantum keys between multiple users. In this paper, we demonstrate its flexibility by focusing on several aspects. We show continuous system operation over a partially deployed 100 km fiber link for multiple days as well as dynamic reconfiguration of the communication partners. The photon pair source enables type-II or type-0 photon pair generation by SPDC as well as various demultiplexing strategies and repetition rates.

Simultaneous water production and electricity generation driven by synergistic temperature-salinity gradient in thermo-osmosis process

Low-grade heat energy is enormous and widely distributed around the world, but it cannot be effectively converted to electricity owing to the small temperature difference and fluctuating heat source. As a promising technology that can convert low-grade heat energy into electricity while obtaining additional freshwater, thermo-osmotic energy conversion has attracted attentions of numerous researchers. However, traditional thermo-osmotic energy conversion technologies lack the utilization of the accompanying variation in salinity gradients throughout the process. In this study, a hybrid system was presented to achieve simultaneous freshwater production and electricity generation by combining thermo-osmosis system with a salinity gradient power recovery module. Continuous operation of the thermo-osmosis system will naturally produce a range of salinity differences, which will then be converted into electricity by the salinity gradient power recovery module. Our results show that this hybrid system can optimally increase the electricity output by ∼0.99 W m−2 over the conventional thermo-osmotic energy conversion system. Overall, our research demonstrates a promising device to harvest low-grade waste heat for co-generation of electricity and freshwater. This innovative approach has the potential to broaden the application possibilities of thermo-osmosis technology.

Experimental validation of passive and active fault-tolerant controls against sensor faults in a proton exchange membrane fuel cell system

A fuel-cell system is interconnected with subsystems such as the stack, thermal/water management systems, air/fuel supply systems, and inverter; if an abnormality occurs, operational efficiency and availability of the entire system can decrease. However, when faults occur in the system, terminating system operations or replacing faulty parts every time can be expensive and inefficient. Instead, appropriate decision-making is required, with fault-tolerant control considered an appropriate solution. This study presents methods and criteria for fault-tolerant control when a fault occurs in a proton exchange membrane fuel cell (PEMFC) system. By configuring a 1 kW residential PEMFC system, a fault occurring in either the thermocouple or mass flow meters – targets for the system control – is diagnosed, and real-time control change is performed instead of immediately repairing the sensor. This approach enables stable and continuous operation of the PEMFC system. The fault-tolerant control method consists of either the feed-back control method, using the real-time predicted value of each control sensor, or the feed-forward method, using the constant control-signal value learned in the normal state; the advantages and limitations of each method are compared. Futhermore, considering the system efficiency, stack durability, and operating control deterioration, a guideline is suggested for applying fault-tolerant control and improving its corresponding effectiveness. For example, fault-tolerant control can resolve a 4.6% decrease in system efficiency caused by a thermocouple fault. This study contributes to improving the system operation rate and reliability by applying fault-tolerant control, thus facilitating efficient decision-making following fault diagnosis.

Treatment of Organic and Sulfate/Sulfide Contaminated Wastewater and Bioelectricity Generation by Sulfate-Reducing Bioreactor Coupling with Sulfide-Oxidizing Fuel Cell.

A wastewater treatment system has been established based on sulfate-reducing and sulfide-oxidizing processes for treating organic wastewater containing high sulfate/sulfide. The influence of COD/SO42- ratio and hydraulic retention time (HRT) on removal efficiencies of sulfate, COD, sulfide and electricity generation was investigated. The continuous operation of the treatment system was carried out for 63 days with the optimum COD/SO42- ratio and HRT. The result showed that the COD and sulfate removal efficiencies were stable, reaching 94.8 ± 0.6 and 93.0 ± 1.3% during the operation. A power density level of 18.0 ± 1.6 mW/m2 was obtained with a sulfide removal efficiency of 93.0 ± 1.2%. However, the sulfide removal efficiency and power density decreased gradually after 45 days. The results from scanning electron microscopy (SEM) with an energy dispersive X-ray (EDX) show that sulfur accumulated on the anode, which could explain the decline in sulfide oxidation and electricity generation. This study provides a promising treatment system to scale up for its actual applications in this type of wastewater.