System Lifetime Research Articles

Unraveling the Cracking Mechanisms of Air Plasma-Sprayed Thermal Barrier Coatings: An In-Situ SEM Investigation

In this research work, real-time three-point bending coupled with the scanning electron microscopy (SEM) technique were used to study the crack formation and growth of air plasma spraying (APS) thermal barrier coatings (TBCs). The acquired micrographs were then used to study the strain fields in the vicinity of the cracking region using digital image correlation (DIC) analysis. Fractography analysis for the fractured regions of the APS coatings was also discussed. Based on real-time observation, it was found that roughness of the coatings’ free surface (e.g., valleys) can promote the initiation of cracks since it acts as stress concentration points. Pores and splats features of the coating microstructure contribute to crack branching and crack path deflection, respectively. The former phenomenon (i.e., crack branching) negatively affects the lifetime of the TBC system as it results in an increased fracture area, while the latter can improve the fracture toughness of the coatings and its durability through improving the coating’s ability to dissipate the energy required for crack propagation.

Adsorption-Based Pretreatment of Irrigation Water to Prevent Water Quality Issues

Access to and the use of irrigation water of adequate quality and targeted nutrient supplementation have become more widespread in recent years. Both crop quality and the irrigation system lifetime are affected by the quality of the water used for irrigation. Micro-irrigation (e.g., drip and sprinkle) is becoming increasingly common alongside the more typical irrigation methods, but it requires expertise and pre-treatment to ensure a proper water supply. The most significant problem is clogging, which can greatly reduce irrigation efficiency. Treatment for irrigation purposes mainly depends on the contaminants that are present in the water. The main treatment options available are biological, electromagnetic and electrostatic treatments, but these have a wide range of effectiveness levels compared to membrane separation technologies. In addition, adsorption treatments are also available, which, depending on the adsorbent used, can greatly improve the pre-treatment of irrigation water. This work provides an overview of adsorbents suitable for the treatment of irrigation water and their effectiveness. The separation of interfering components via adsorption is effective and promising for future application as the expected irrigation demands increase.

Zinc carboxylate optimization strategy for extending Al-air battery system's lifetime

Although Al-air batteries are expected to be the candidates for energy conversion systems in renewable energy market due to the higher energy density, richer reserves, and lighter mass of Al metal, the anode self-discharge is seen as a notorious issue that seriously sacrifices battery durability and stability. Herein, we propose zinc carboxylate inhibition of anode self-discharge for enhancing Al-air battery's lifetime, where the ionized Zn2+ induces a Zn guard on Al surface, and the hydrolysate RCOOH dominates an adsorption layer on the outer surface of Zn, ensuring a double protection for metal anode by means of advanced “one stone two birds” strategy. The results show that the typical zinc carboxylates improve the absolute anticorrosion efficiency of anode greatly, especially the maximum of 92.24% after zinc malate optimization. Furthermore, battery capacity and anode efficiency are as high as 2685.20 mAh g−1 and 90.11% at 20 mA cm−2 respectively. The cyclic discharge lifetime of system (0.12 g fuel) exceeds 19.01 h, which is 1.72 times longer than traditional optimization. Finally, the optimization mechanism is revealed based on Monte Carlo simulation and density functional theory calculation, which the double CO groups in the hydrolysate of zinc malate dominates the harmonious interaction between RCOOH adsorption layer and active metals, exhibiting a high-energy efficiency and long-lifetime Al-air battery power system.

Evaluation of the degradation of a PV panel in an arid zone; case study Biskra (Algeria)

Even for a limited period of time, weather conditions including solar radiation, temperature, wind, UV intensity, humidity, and precipitation have an effect on the degradation and efficiency of PV panels. As a result, these are the primary variables that impact the lifetime and durability of a photovoltaic system. Thus, increasing the efficiency of PV modules requires overcoming the critical problem of degradation. The current study aims to examine the deterioration of a poly-crystalline silicon photovoltaic panel that was exposed to outside conditions for four years in Biskra’s arid climate (Algerian town). To assess the performance of the tested PV module, two characterization techniques—I-V and P-V characterization as well as visual inspection—have been applied.Under normal conditions, a new model for determining the five criteria (a, Rs, Rp, I0, and Iph) has been developed using curve-fitting method. It was adapted for panels with and without degradation. By estimating how those parameters degrade, a new technique for identifying damaged panels has been created. The results highlight the dominance of the EVA degradation mode, which has a significant effect on the degradation rates of Rs (54.27%), Rp (−62.68%), and Iph (77.45%), as well as the evolution of the I-V and P-V curves.

Technical and economic analysis of a pump as a turbine for rural electrification

ABSTRACT Electricity is one of the essential requirements for the economic development of a country. In Ethiopia, more than half of the total population does not have access to electric power. Micro-hydropower (MHP) is one of the most feasible renewable energy options for providing reliable electricity to rural areas. However, in low-income countries such as Ethiopia, the high price of a purpose-made turbine to generate electricity from MHP resources is difficult. This paper presents the feasibility study of a pump as a turbine (PAT) for MHP applications with and without impeller blade modification. The analysis was conducted in terms of initial investment cost, the net present value, payback periods, and the cost of energy. Decreasing blade thickness, blade tip rounding, adjusting blade inlet angle, and blade grooving, then comparing the result with PAT without modification and cross-flow turbine are the modification techniques considered in this research. Based on the projected system lifetime, the equivalent cost of power for the PAT and cross-flow turbines are 0.065 and 0.100 $/kWh respectively. The cross-flow turbine's payback period is 6.04 years, which is significantly longer than the PATs payback period of 3.42 years. From the entire study, it can be concluded that the MHP coupled with PAT provides a lower payback period and cheaper power production. Whereas, impeller blade modification has no significant advantage from the economic point of view. Generally, the impeller modification cost needs to be less than or equal to 25% of the initial cost of the PAT to use the less cost advantage of the PAT.

On [formula omitted]-out-of-[formula omitted] systems with homogeneous components and one independent cold standby redundancy

In this note, we study a k-out-of-n system with component lifetimes linked by Archimedean (survival) copula and independent of the lifetime of a cold standby redundancy. We derive the survival function and the residual life function of the redundant system. Also, we examine how the redundancy and the system structure impact the system reliability through developing the usual stochastic order on system lifetime. In particular, for parallel systems we investigate the role played by the component lifetime, the generator of Archimedean copula, and the starting time of the redundancy as well. The present framework well relates to the real situation and thus the main results are instructive to reliability engineers.

An advanced treatment process for 3-high wastewater discharged from crude oil storage tanks.

The wastewater discharged from crude oil storage tanks (WCOST) contains high concentrations of salt and metal iron ions, and high chemical oxygen demand (COD). It belongs to "3-high" wastewater, which is difficult for purification. In this study, WCOST treatments were comparatively investigated via an advanced pretreatment and the traditional coagulation-microfiltration (CMF) processes. After WCOST was purified through the conventional CMF process, fouling occurred in the microfiltration (MF) membrane, which is rather harmful to the following reverse osmosis (RO) membrane unit, and the effluent featured high COD and UV254 values. The analysis confirmed that the MF fouling was due to the oxidation of ferrous ions, and the high COD and UV254 values were mainly attributable to the organic compounds with small molecular sizes, including aromatic-like and fulvic-like compounds. After the pretreatment of the advanced process consisting of aeration, manganese sand filtration, and activated carbon adsorption in combination with CMF process, the removal efficiencies of organic matter and total iron ions reached 97.3% and 99.8%, respectively. All the water indexes of the effluent, after treatment by the advanced multi-unit process, meet well the corresponding standard. The advanced pretreatment process reported herein displayed a great potential for alleviating the MF membrane fouling and enhanced the lifetime of the RO membrane system in the 3-high WCOST treatment.

How national decarbonisation scenarios can affect building refurbishment strategies

Energy transition is radically changing national energy systems. Nevertheless, the dynamics of this transformation are not considered by end-users in the design of building systems. The present work aims at assessing how the renewable share increase, in both electricity and gas grids, can affect building energy performance. To do this, building energy performance indicators, taking into account growing renewable shares, have been proposed. Four national decarbonisation scenarios have been considered. In a case-study in Italy, conventional boilers, heat pumps, combined heat and power plants and hybrid systems have been analysed. Heat pumps turn out to be the best option if the renewable penetration in the power grid is higher than 40%. The substitute natural gas deployment can increase the competitiveness of cogeneration systems, but not enough to represent the best configuration. National decarbonisation scenarios significantly affect the primary energy and emissions savings of building refurbishment strategies. Conventional indicators, taking primary energy factors as fixed, lead to correct assessment for the reference year, but are unable to describe the actual building energy performance over the system lifetime. Depending on the scenario, the average specific primary energy consumption ranges in 17% and 55% lower than the one assessed with conventional analyses.

Lifetime Extension Approach Based on the Levenberg–Marquardt Neural Network and Power Routing of DC–DC Converters

The power conversion system based on the modular connection has widespread applications in various power electronic systems. To accurately estimate the state of health without recognizing the systematic mathematical model and to extend the lifetime, this paper proposes a lifetime extension approach based on the Levenberg-Marquardt back propagation neural network (LM-BPNN) and power routing of interleaved DC-DC boost conversion systems. The LM-BPNN model is constructed based on the voltage, current, and temperature data generated by the system. On the basis of the trained LM-BPNN, the real-time cumulated damage estimation of each power cell in the conversion system can be accomplished. Applying the power routing concept, the DC-DC boost conversion system allocates different power to the cells according to the cumulated damage of each cell, thereby delaying the failure of cells with higher cumulated damage. Numerical simulation results show that the proposed lifetime extension approach can extend the overall system lifetime. Furthermore, an experimental setup of the interleaved DC-DC boost conversion is constructed to verify the proposed approach, which is of great significance for predictive maintenance in the industrial system.

Study of Solar Photovoltaic Array for Air Conditioning System

The vapor compression refrigeration (VCR) and air conditioning systems are widely used for cooling, refrigeration, air conditioning, heating purposes and consumes more than 33% of the world energy. Solar energy is available abundantly as renewable energy source in summer when requirement of comfort is in peak demand. The electrical energy is replaced with solar energy by properly selecting solar panels, battery, inverter, charge controllers for storing fruits and vegetables in rural areas due to uncertain pattern of grid electricity. In the paper, solar power VCR system is designed and simulated with Simulink to estimate the performance in terms of irradiance and temperature. It is found that with rise in irradiance, current and power outcome increases. The solar system is CO2 free with substantial saving of 9700 whereas conventional VCR system produces 5292 kg of CO2 during life time of solar PV system.

Application of the reversible step-up and step-down pulse converter as a charging and discharging device in an autonomous system of electric power supply

Formulation of the problem. The structure shown in Figure 1 is widely used to build spacecraft power supply systems. It contains a solar battery in series and voltage regulator, which a load is connected to its output. To supply power to the load when the solar panel has no or insufficient capacity, the power supply system uses a battery pack which is charged and discharged by means of a charge-discharge device connected between the output of the voltage regulator and the battery pack. The power supply can be used to build power supply systems for a wide range of autonomous objects, such as unmanned aerial vehicles with long flight times, unattended weather stations, and environmental monitoring stations. In a power supply system with the structure shown in Figure 1, each of the devices can stabilize the output voltage: a voltage regulator, a discharge device and a battery charger. In such a power supply system, the operation of the charger and the discharger are separated in time, allowing them to function together. The use as a charge-discharge boost-decrease reversible pulse voltage converter with a high efficiency allows minimizing the number of elements in the power circuit of the device due to the possibility of reversing the energy flow reversal, which will improve the weight and size characteristics of the system and increase to increase its reliability. The purpose is to show the feasibility of using a converter with a high efficiency factor and the possibility of reversing the energy flow as a charge-discharge device as part of the power supply system of an autonomous object. To develop a model and confirm the possibility of operating the pulse converter as a charger in two modes: in the mode of providing a given charging current of the battery and in the mode of charging the battery with a decreasing current at a given voltage on the battery. Results. The expediency of using a reversible pulse converter with a high efficiency factor and the possibility of reversing the energy flow as a charger in the power supply system of an autonomous object is shown. A model has been developed and confirmed of the converter as a charger in two modes: in the mode of providing a given charging current of the battery and in the mode of charging the battery with a decreasing current at a given voltage on the battery pack. Practical Significance. The use of a reversible pulse converter as a single charge-discharge converter in the power supply system of an autonomous object will improve the mass-size characteristics, efficiency and reliability of the power supply system and increase life time of active operation of autonomous object as a whole Keywords: power supply system, autonomous object, solar battery, accumulator battery, pulse converter, charge-discharge device.

Stability Constraints on Reliability-Oriented Control of AC Microgrids – Theoretical Margin and Solutions

Reliability is of importance for operation maintenance and cost reduction in power electronics and systems. Based on the reliability models of power devices, reliability-oriented power sharing in microgrids enforces the redistribution of power among converters to prolong the lifetime of the entire system, and droop control is typically used herein. However, this could affect the system stability, which contradicts the prerequisite of secure operation. In light of the above, this article is aimed to reveal this limitation of reliability-oriented droop control and emphasize its impact on system stability. Accordingly, a framework of stability-constrained reliability-oriented droop control is proposed, together with solutions that can help to enhance the stability. With this, the reliability of the system could be further improved without violating the stability criteria. Moreover, experimental tests and long-term reliability evaluations are included, which demonstrates that the aforementioned issues can be effectively addressed alongside with the proposed framework and solutions.

Optimization of High Power SMES for Naval Applications

The electrification of transport has been no exception for waterborne vessels. The reduction of emissions, especially dur-ing port maneuvering and operation, has accelerated the transi-tion from fossil fuel to electric propulsion. Moreover, military ves-sels, with specialized electric weapon systems, or civil vessels, like offshore wind tug boats, have high power systems that additionally contribute to a higher electrification of the ship grid. Energy stor-age systems are essential to meet the power load economically and to improve the system`s reliability and efficiency. Therefore, the use of high energy density storage systems, as chemical batteries, or hydrogen fuel cells, has experienced a significant increase in de-mand. However, during high frequency load fluctuations, high en-ergy density storage systems are not capable to actuate, since the discharge rate of these systems is physically limited, which may provoke: deterioration and reduction of the lifetime of the storage systems, voltage and frequency fluctuation of the ship grid. To overcome this limitation, this paper studies the use of a Supercon-ducting Magnetic Energy Storage (SMES) as a supporting energy storage device for the ship grid. The guidelines for dimensioning, in power and energy, the SMES are stablished. Furthermore, an optimization method is developed in order to compare different superconducting materials, and operating temperatures.

Memory Carousel: LLVM-Based Bitwise Wear Leveling for Nonvolatile Main Memory

Emerging non-volatile memory yields, alongside many advantages, technical shortcomings, such as reduced cell lifetime. Although many wear-leveling approaches exist to extend the lifetime of such memories, usually a trade-off for the granularity of wear-leveling has to be made. Due to iterative write schemes (repeatedly sense and write), wear-out of memory in certain systems is directly dependent on the written bit value and thus can be highly imbalanced, requiring dedicated bit-wise wear-leveling. Such a bit-wise wear-leveling so far has only be proposed together with a special hardware support. However, if no dedicated hardware solutions are available, especially for commercial off-the-shelf systems with non-volatile memories, a software solution can be crucial for the system lifetime. In this work, we propose entirely software-based bit-wise wearleveling, where the position of bits within CPU words in main memory is rotated on a regular basis. We leverage the LLVM intermediate representation to adjust load and store operations of the application with a custom compiler pass. Experimental evaluation shows that the lifetime by applying local rotation within the CPU word can be extended by a factor of up to 21×. We also show that our method can incorporate with coarser-grained wear-leveling, e.g. on block granularity and assist achievement of higher lifetime improvements.

On reliability assessment of weighted k-out-of-n systems with multiple types of components

ABSTRACT This paper studies the reliability function of a weighted k -out-of- n system with multiple types of components. A weighted system with M different types of components is considered and two real-life scenarios for the operation of the system are defined. In the first one, it is assumed that the system operates if the accumulated weight of all active components is more than a predetermined threshold k , otherwise the system fails. In the second scenario, the system is assumed to operate if the total weight of the operating components of type i is more than or equal to the corresponding threshold k i , for at least m types of components, m ≤ M . Our approaches in assessing the reliability function of the system lifetime rely on the notion of survival signature corresponding to multi-type weighted k -out-of- n system. The formulas for the proposed survival signature are presented and the corresponding computational algorithms are also given. To examine the theoretical results, the reliability function and other aging characteristics of a wind farm (system) consisting of three plants located in three different regions are assessed numerically and graphically. Finally, an allocation problem to determine the best choice for the distribution of each type in the weighted k -out-of- n systems is studied.

EUV debris mitigation using magnetic nulls

Next generation EUV sources for photolithography use light produced by laser-produced plasmas (LPP) from ablated tin droplets. A major challenge for extending the lifetime of these devices is mitigating damage caused by deposition of tin debris on the sensitive collection mirror. Especially difficult to stop are high energy (up to 10 keV) highly charged tin ions created in the plasma. Existing solutions include the use of stopping gas, electric fields, and magnetic fields. One common configuration consists of a magnetic field perpendicular to the EUV emission direction, but such a system can result in ion populations that are trapped rather than removed. We investigate a previously unconsidered mitigation geometry consisting of a magnetic null by performing full-orbit integration of the ion trajectories in an EUV system with realistic dimensions and optimize the coil locations for the null configuration. The magnetic null prevents a fraction of ions from hitting the mirror comparable to that of the perpendicular field, but does not trap any ions due to the chaotic nature of ion trajectories that pass close to the null. This technology can potentially improve LPP-based EUV photolithography system efficiency and lifetime and may allow for a different, more efficient formulation of buffer gas.

Age and Isotope-Geochemical Characteristics of Ta, Nb, W, Sn Mineralization Associated with Rare-Metal Granites (Khangilay Ore District, Eastern Transbaikalia)

The age relations between the formation of the parent massif and the crystallization time of the associated ore mineralization were established based on isotope-geochronological study of the massif-deposits of the Khangilay ore cluster with various metallogenic specialization in Eastern Transbaikalia. In the Orlovka Li–F granite massif, the crystallization time of columbite–tantalite (145 ± 1 Ma) and cassiterite (144.2 ± 0.3 Ma) (U-Pb, ID-TIMS) is almost identical to the crystallization time of zircon (140.6 ± 2.9 Ма (U-Pb, SHRIMP) and 145 ± 1 Ma (U-Pb, CA-ID-TIMS)), which is an age marker of the formation of massifs. This fact testifies to the magmatogenic nature of rare-metal mineralization. In the Spokojnoye massif – the “standard type” of rare-metal peraluminous granites—a 0.6–3.8 Ma time gap was revealed between the time of massif formation (141.3 ± 1.8 Ма, U-Pb, SHRIMP, 146.9 ± 0.7 Ма, Rb-Sr isotopic system) and crystallization of wolframite (141.8 ± 0.6, Rb-Sr isotopic system and 140.1 ± 1.4 Ма, Sm-Nd isotopic system). This interval likely corresponds to the life time of the hydrothermal system, which produced tungsten mineralization.

A lifetime prediction method for Lithium-ion batteries considering storage degradation of spare parts

Standby redundancy is a common fault-tolerant technique to ensure uninterrupted operation and enhance the reliability of Lithium-ion (Li-ion) batteries. In practice, the performance of standby Li-ion batteries has been found deteriorating with their storage, which may decrease the standby system's lifetime (SSL). Unfortunately, SSL prediction has not been investigated thoroughly by existing researches. Therefore, this paper proposes an iterative method for SSL prediction considering the storage degradation of spare parts. The operating and storage degradation processes are respectively described by two nonlinear Wiener-process-based models, based on which an iterative solution of the SSL under the concept of the first passage time (FPT) is provided. Additionally, random effects have been incorporated, and the proposed iterative method for SSL prediction has also been extended to the case with unit-to-unit variability. Both the numerical simulations and Li-ion batteries example are provided for illustration.

Preparing to work with artificial intelligence: assessing WHS when using AI in the workplace

PurposeArtificial Intelligence (AI) systems play an increasing role in organisation management, process and product development. This study identifies risks and hazards that AI systems may pose to the work health and safety (WHS) of those engaging with or exposed to them. A conceptual framework of organisational measures for minimising those risks is proposed.Design/methodology/approachAdopting an exploratory, inductive qualitative approach, the researchers interviewed 30 experts in data science, technology and WHS; 12 representatives of nine organisations using or preparing to use AI; and ran online workshops, including with 12 WHS inspectors. The research mapped AI ethics principles endorsed by the Australian government onto the AI Canvas, a tool for tracking AI implementation from ideation via development to operation. Fieldwork and analysis developed a matrix of WHS and organisational–managerial risks and risk minimisation strategies relating to AI use at each implementation stage.FindingsThe study identified psychosocial, work stress and workplace relational risks that organisations and employees face during AI implementation in a workplace. Privacy, business continuity and gaming risks were also noted. All may persist and reoccur during the lifetime of an AI system. Alertness to such risks may be enhanced by adopting a systematic risk assessment approach.Originality/valueA collaborative project involving sociologists, economists and computer scientists, the study relates abstract AI ethics principles to concrete WHS risks and hazards. The study translates principles typically applied at the societal level to workplaces and proposes a process for assessing AI system risks.

Predicting System Degradation with a Guided Neural Network Approach.

Evaluating the physical degradation behavior and estimating the lifetime of engineering systems and structures is crucial to ensure their safe and reliable operation. However, measuring lifetime through actual operating conditions can be a difficult and slow process. While valuable and quick in measuring lifetimes, accelerated life testing is often oversimplified and does not provide accurate simulations of the exact operating environment. This paper proposes a data-driven framework for time-efficient modeling of field degradation using sensor measurements from short-term actual operating conditions degradation tests. The framework consists of two neural networks: a physics discovery neural network and a predictive neural network. The former models the underlying physics of degradation, while the latter makes probabilistic predictions for degradation intensity. The physics discovery neural network guides the predictive neural network for better life estimations. The proposed framework addresses two main challenges associated with applying neural networks for lifetime estimation: incorporating the underlying physics of degradation and requirements for extensive training data. This paper demonstrates the effectiveness of the proposed approach through a case study of atmospheric corrosion of steel test samples in a marine environment. The results show the proposed framework's effectiveness, where the mean absolute error of the predictions is lower by up to 76% compared to a standard neural network. By employing the proposed data-driven framework for lifetime prediction, systems safety and reliability can be evaluated efficiently, and maintenance activities can be optimized.