Operational Stability Research Articles

Interfacial Modification of ZnO/ZnMgO Bilayer for Efficient and Stable InP Quantum Dot Light-Emitting Diodes via Ultraviolet Ozone Treatment.

The development of efficient charge transport layers is crucial for realizing high-performance and stable quantum dot light-emitting diodes (QD-LEDs). The use of a ZnO/ZnMgO bilayer as an electron transporting layer (ETL) has garnered considerable attention. This configuration leverages the high electron mobility of ZnO and the favorable surface state of ZnMgO. Furthermore, the versatility of this configuration extends to its wide range of thickness tunability, rendering it suitable for the construction of thick devices for top-emitting structures with microcavities. However, despite the promising attributes of this bilayer configuration, the impact of the ZnO/ZnMgO bilayer ETL interface on QD-LEDs performance remains largely unexplored. Thus, this study investigated the effect of ultraviolet ozone (UVO) treatment on the stabilization of the ZnO/ZnMgO interface. UVO treatment was found to significantly enhance luminance uniformity across the QD-LEDs emission area while improving operational stability by over 4-fold. Comprehensive analyses employing X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy confirmed that UVO treatment significantly reduced the defect states of the hydroxyl groups and removed the insulating native ethanolamine ligands, thereby facilitating improved and uniform electron transport. Moreover, the effectiveness of UVO treatment in enhancing electron transport was supported by impedance analyses. Therefore, this paper presents an effective approach for enhancing the interface of a highly potent ZnO/ZnMgO bilayer ETL, which can ultimately improve the luminance uniformity and stability of QD-LEDs.

Jamming Giant Molecules at Interface in Organic Photovoltaics to Improve Performance and Stability.

A novel approach for depositing the giant molecule acceptor (GMA) at the donor-acceptor interface to enhance the efficiency and stability of organic photovoltaic (OPV) devices through a designed interface-enhanced layer-by-layer device fabrication protocol is proposed. The giant molecule acceptor DQx-Ph is mixed with the polymer donor in the bottom layer to form a polymer donor fibril phase and a mixed phase, followed by subsequent deposition of the main acceptor L8-BO. The L8-BO solution swells the bottom layer and alters the localized morphology of the mixing phase, introducing L8-BO fibrillar crystallization and pushing DQx-Ph giant molecules outwards to the fibril interfaces. Through this approach, the localized morphology and optoelectronic property of the bulk heterojunction are optimized. This configuration maintains the superior transport properties of L8-BO while integrating the high open-circuit voltage characteristics of DQx-Ph. Additionally, exciton dissociation and charge generation are simultaneously enhanced, with suppressed energy losses. A power conversion efficiency of 19.9% with improved operational stability is achieved, underscoring the importance of GMA interface jamming in advancing OPV technology. This study provides new insights into the development of ancillary OPV materials to overcome the critical limitations in OPV, revealing innovative approaches for photovoltaic technologies.

ANALISIS PERMINTAAN KONSUMEN TERHADAP LAYANAN TRANSPORTASI ONLINE DI KOTA MALANG

This research aims to measure the extent of consumer demand changes for online transportation services in Malang City following a tariff increase and to identify the factors influencing the demand for these services. This research utilized a quantitative approach and was analyzed through the wilcoxon test and multiple linear regression analysis. The findings reveal significant changes in consumer demand after the tariff hike. Specifically, the variable of online transportation service tariffs shows a positive and significant influence. Income demonstrates a positive but insignificant effect, while the variables of conventional transportation services tariffs and travel speed each indicate a negative influence that is not significant and significant, respectively, on the demand for online transportation services. Based on these findings, it is crucial for online transportation service companies to maintain comfort and security, as these factors are top priorities for consumers in choosing transportation services. Additionally, the government can contribute to maintaining operational stability for companies, ensuring safety for users, and overall stability in the transportation ecosystem.

Mesoporous structured MoS2 as an electron transport layer for efficient and stable perovskite solar cells.

Mesoporous structured electron transport layers (ETLs) in perovskite solar cells (PSCs) have an increased surface contact with the perovskite layer, enabling effective charge separation and extraction, and high-efficiency devices. However, the most widely used ETL material in PSCs, TiO2, requires a sintering temperature of more than 500 °C and undergoes photocatalytic reaction under incident illumination that limits operational stability. Recent efforts have focused on finding alternative ETL materials, such as SnO2. Here we propose mesoporous MoS2 as an efficient and stable ETL material. The MoS2 interlayer increases the surface contact area with the adjacent perovskite layer, improving charge transfer dynamics between the two layers. In addition, the matching between the MoS2 and the perovskite lattices facilitates preferential growth of perovskite crystals with low residual strain, compared with TiO2. Using mesoporous structured MoS2 as ETL, we obtain PSCs with 25.7% (0.08 cm2, certified 25.4%) and 22.4% (1.00 cm2) efficiencies. Under continuous illumination, our cell remains stable for more than 2,000 h, demonstrating improved photostability with respect to TiO2.

Engineering Spacer Conjugation for Efficient and Stable 2D/3D Perovskite Solar Cells and Modules

Incorporating 2D perovskite in 3D perovskite absorber holds great potential to improve the stability and efficiency of perovskite solar cells (PSCs). However, the bulky‐cation‐based 2D structures often exhibit poor charge transport and are prone to formation of charge‐extraction barrier that impedes efficient device operation. We address these issues by introducing aromatic spacers with enhanced molecular conjugation. Among our tested aromatic spacers, the pyrenylbutanamine (PyBA) spacer was shown to endow 2D perovskites with superior charge transport properties and efficient charge extraction from the bulk perovskite in 2D/3D PSCs, due to the highest degree of conjugation. As a result, we achieved a power conversion efficiency of up to 25.3% in a 0.16‐cm2 single cell and 21.0% in a 24.8‐cm2 module. Moreover, the incorporated PyBA substantially raised the resistance of 2D/3D PSCs against moisture and ion migration, resulting in enhanced environmental, thermal, and operational stability. Notably, the PyBA‐based devices retained over 90% of their initial efficiency after 2000 hours at 25 ℃ and 80% relative humidity, or 1000 hours at 85 ℃ and 85% humidity, or 3000 hours of operation under continuous 1‐Sun illumination at 40 ℃, showcasing their enhanced stability compared to previously reported 2D/3D PSCs.

Organic Salt Buffer Layer Enables High‐Performance NiOx‐Based Inverted Perovskite Solar Cells

The merits of a low‐cost fabrication process, suitable band structure, excellent wettability to perovskite precursor, and outstanding stability ensure NiOx as a hole transport material with beneficial characteristics to construct high‐performance perovskite solar cells (PSCs). However, direct contact between perovskite and NiOx causes delamination and chemical instability and thus results in poor carrier transport and short device lifespan. Here, we propose a solution for this issue by introducing an organic salt additive 4‐(trifluoromethyl) benzylammonium formate (TFMBAFa) in the perovskite precursor to passivate perovskite film and NiOx@(2‐(3,6‐dimethyl‐9H‐carbazol‐9‐yl) ethyl) phosphonic acid (Me‐2PACz) composited hole transport layer (HTL), and thus construct a buffer layer between perovskite‐HTL interface. The effective diminishing of NiOx/perovskite interfacial reactions and defects results in enhanced carrier transport. Consequently, the target device achieves simultaneous improvements in power conversion efficiency (24.2%), storage stability (T100 > 1400 h), thermal stability (T80 > 1000 h), and operational stability (T70 > 850 h), where T100, T80, and T70 refer to the retention of 100%, 80%, and 70% of initial PCE, respectively. This work provides an effective strategy to advance the performance of NiOx‐based inverted PSCs.

Engineering Spacer Conjugation for Efficient and Stable 2D/3D Perovskite Solar Cells and Modules.

Incorporating 2D perovskite in 3D perovskite absorber holds great potential to improve the stability and efficiency of perovskite solar cells (PSCs). However, the bulky-cation-based 2D structures often exhibit poor charge transport and are prone to formation of charge-extraction barrier that impedes efficient device operation. We address these issues by introducing aromatic spacers with enhanced molecular conjugation. Among our tested aromatic spacers, the pyrenylbutanamine (PyBA) spacer was shown to endow 2D perovskites with superior charge transport properties and efficient charge extraction from the bulk perovskite in 2D/3D PSCs, due to the highest degree of conjugation. As a result, we achieved a power conversion efficiency of up to 25.3% in a 0.16-cm2 single cell and 21.0% in a 24.8-cm2 module. Moreover, the incorporated PyBA substantially raised the resistance of 2D/3D PSCs against moisture and ion migration, resulting in enhanced environmental, thermal, and operational stability. Notably, the PyBA-based devices retained over 90% of their initial efficiency after 2000 hours at 25 ℃ and 80% relative humidity, or 1000 hours at 85 ℃ and 85% humidity, or 3000 hours of operation under continuous 1-Sun illumination at 40 ℃, showcasing their enhanced stability compared to previously reported 2D/3D PSCs.

Backward motion suppression in space-constrained piezoelectric pipeline robots

In response to the current challenges of detecting micro pipelines, a micro pipeline robot based on the principle of piezoelectric inertia stick-slip drive was proposed in this paper, which can be effectively applied to the detection and maintenance of micro pipelines. However, during the analysis of the robot's displacement trajectory, it was observed that using inertial drive could cause the backward motion of the robot. This may adversely affect the accuracy and stability of the robot's operation within the micro pipelines. Therefore, a novel control method is derived from the original pipeline robot structure. By affixing piezoelectric sheets to the driving feet of the robot to adjust their deformation and subsequently employing collaborative control of piezoelectric sheets and piezoelectric stacks to regulate friction between the driving feet and the pipe wall, the backward motion of the robot was effectively mitigated. Compared to existing backward motion suppression methods, the approach proposed in this paper has a minimal impact on the actuator's size, allowing for flexible adaptation to various space-constrained applications, while also offering the advantage of a simple control strategy. After determining the structure and working principle, deformation analysis of the driving foot and dynamic simulation analysis of the driving system were conducted. These analyses provide insights into the relationship between mechanical and electrical parameters and output performance within the driving system, thereby validating the feasibility of the control method. Subsequently, a prototype was fabricated, and its output performance was tested. Results demonstrate that this control method can effectively suppress inertial backward motion, achieving a suppression rate close to 100 %. This research presents a novel idea and methodology for mitigating the backward motion of piezoelectric inertial stick-slip actuators with driving foot structures.

Asymmetric Modification of Carbazole Based Self-Assembled Monolayers by Hybrid Strategy for Inverted Perovskite Solar Cells.

Carbazole-based self-assembled molecules (SAMs) are widely applied in inverted perovskite solar cells (iPSCs) due to their unique molecular properties. However, the symmetrical structure of the carbazole-based SAMs makes it difficult to finely regulate their performance, which impedes the further enhancement of the efficiency and stability of iPSCs. This work shows that by building an asymmetric carbazole core, the crucial properties of SAM molecules can be effectively regulated. It has been confirmed that the hybrid thieno[2,3-b]thiophene unit of this asymmetric core governs the energy level, the surface wettability, and the defect passivation capability of the SAMs, while the substituent of core has a greater impact on the molecular dipole and device stability. The synergistic effects from thieno[2,3-b]thiophene and fluorine lead to the KF-derived iPSC demonstrating a certified power conversion efficiency (PCE) of 25.17% and excellent operational stability. This hybrid design concept offers a promising approach for the further structural modification of SAMs in iPSCs.

Influence of electrode transparency on the plasma properties of a cylindrical IEC plasma source

This study investigates the influence of cathode and anode grid transparency on the plasma properties of a Cylindrical Inertial Electrostatic Confinement plasma source. The primary focus is to elucidate how variations in the transparency of the electrodes impact plasma characteristics and the operational performance of the source, particularly during spray jet mode. Employing optical emission spectroscopy (OES) and Langmuir probe diagnostics, the plasma behavior is analyzed comprehensively. The results demonstrate that cathode transparency has a pronounced effect on discharge current and plasma density within the cathode. Conversely, the transparency of the anode has only a little influence the ignition characteristics and operational stability of the plasma source. The findings highlight the importance of utilizing cathode transparency to adjust both the pressure and voltage operating ranges of the IEC source in spray jet mode, optimizing its performance for various applications.

Time-delay feedback control on vertical vibration of maglev train under unsteady aerodynamic force

The stability and safety of maglev trains are significantly affected by unsteady aerodynamic forces during high-speed operation. In this paper, we employ a time-delay feedback control strategy to suppress the nonlinear vertical vibrations of maglev train under periodic unsteady aerodynamic force. Firstly, the amplitude-frequency response equation of the maglev vehicle is derived using the multiple scales method, and the stability of the steady-state solutions is determined. Then, the influences of velocity feedback gain coefficient and velocity time delay on the nonlinear vibrations of the maglev vehicle are investigated. The optimal value range of the time delay is identified. The results demonstrate that the time delay feedback control can effectively suppress the nonlinear vibration of maglev vehicles and enhance their operational stability under the premise of reasonable selection of time delay parameters. The theoretical research presented in this paper can serve as a theoretical reference for the design, improvement, and optimization of control systems for high-speed maglev trains.

Robust distribution networks reconfiguration considering the improvement of network resilience considering renewable energy resources

The integration of renewable energy sources into smart distribution grids poses substantial challenges in maintaining grid stability, efficiency, and reliability due to their inherent variability and intermittency. This study addresses these challenges by proposing a novel two-level optimization model aimed at enhancing operational efficiency and robustness in smart distribution grids. The model synergistically integrates renewable energy sources, energy storage systems, electric vehicles, and demand-side management through a dynamic reconfiguration approach. It employs a robust optimization framework combined with a two-stage second-order cone optimization model to manage real-time operations and strategic grid reconfiguration. Key findings from simulations on the IEEE 33 and 69-bus networks underscore the model’s effectiveness. In the 33-bus system, implementing the demand response program led to a significant reduction in power losses, from 0.64 MW to 0.52 MW, and improved voltage stability, with the minimum voltage increasing from 0.970 to 0.980 p.u. Similarly, in the 69-bus system, power losses decreased from 0.85 MW to 0.79 MW, and voltage stability improved, with the minimum voltage rising from 0.962 to 0.972 p.u. The model also demonstrated reduced energy procurement needs, showcasing its impact on enhancing grid efficiency and reliability. These results highlight the model’s potential for advancing smart grid management strategies, offering significant improvements in operational performance and stability under varying demand conditions.

Navigating the Impact of Immigration Policies on Universities: A Leadership Model Approach

This study explores the multifaceted challenges universities may face as a result of alterations in immigration policies. Tightened regulations lead to decreases in international student enrollment. By drawing upon various theoretical frameworks, including transformational leadership, change management, and cultural dimensions, this study offers a comprehensive strategy to address the financial, social, and cultural implications of immigration policy shifts. The study examines the impact of policy changes on employees, highlighting potential challenges such as burnout and disengagement. Proactive measures, including flexible work arrangements and mental health support services, are recommended to mitigate these impacts. Financial implications are addressed through developing contingency plans and reassessing financial strategies to maintain operational stability. Furthermore, the study underscores the importance of preserving campus cultural exchange opportunities and diversity initiatives through virtual programs, partnerships, and curriculum integration. Leadership models, particularly transformational leadership, provide a guiding framework for navigating organizational change. The study advocates for clear communication, employee empowerment, and alignment with the institution’s values to foster resilience. Additionally, Kotter’s 8-Step Model of Change Management offers a structured approach to addressing challenges, emphasizing the importance of urgency, vision, and cultural integration. Through proactive measures informed by theoretical insights, universities can navigate the challenges of immigration policy changes while upholding their commitment to diversity, inclusion, and academic excellence. This study contributes valuable insights for higher education institutions grappling with regulatory shifts, offering actionable recommendations for fostering resilience and adaptation in a rapidly changing landscape.

Optimization of solid oxide electrolysis cells using concentrated solar-thermal energy storage: A hybrid deep learning approach

The Solid Oxide Electrolysis Cell (SOEC) represents a cutting-edge solution for the conversion of CO2 and H2O into syngas, offering significant economic and environmental benefits. However, the process requires substantial high-temperature heat inputs, traditionally supplied by electricity. This study introduces a novel approach leveraging concentrated solar radiation as a renewable heat source for SOEC, addressing the challenge of its inherent fluctuations through the integration of Thermal Energy Storage (TES) systems. We propose a hybrid model that combines multi-physics simulation with a deep learning algorithm, enabling rapid optimization of the electrolysis process under real-time direct normal irradiance conditions. Our findings demonstrate that the inclusion of TES within the system architecture results in a remarkable 53 % reduction in temperature variation rate at the SOEC inlet, ensuring operational stability and efficiency. Furthermore, by fine-tuning capacity parameters, we have developed a control strategy that harmonizes efficiency with safety performance. The robustness of our system is underscored by its resilience to step changes, achieving a 75 % reduction in temperature fluctuations. This research contributes a pioneering method for the real-time optimization and control of SOEC systems, harnessing the power of TES to drive sustainable energy conversion with enhanced reliability and economic viability, facilitating precise and swift predictive capabilities even under dynamic operating conditions.

Resonance Suppression Method Based on Hybrid Damping Linear Active Disturbance Rejection Control for Multi-Parallel Converters

The parallel operation of multiple LCL-type converters will result in a deviation of the resonant frequency and resonance phenomena. The occurrence of harmonic resonance can cause problems such as an increase in harmonic voltage and current. This can lead to the malfunction of relay protection and automatic devices, causing damage to system equipment. In severe cases, it can cause accidents and threaten the safe operation of the power system. A hybrid damping active disturbance rejection control (HD-ADRC) method is proposed in this paper to suppress the harmonic resonance of parallel LCL-type converters. First, a third-order linear disturbance rejection controller (LADRC) including the linear extended-state observer and the error-feedback control rate is designed based on LCL-type converter model analysis. The proposed method considers the resonance couplings caused by both internal and external disturbances as the total disturbance, thus improving the anti-disturbance capabilities as well as the operational stability of converters in parallel. Then, a hybrid damping control is proposed to reconstruct the damping characteristics of converters to suppress the parallel resonance spike and reduce the resonance frequency offset. And the parameter selection of the control system is optimized through a stability analysis of the tracking performance and anti-disturbance performance of the HD-ADRC controller. Finally, all the theoretical considerations are verified by simulation and experimental results based on the Matlab/Simulink 2018B and dSpace platform. The simulation and experimental results show that the PI controller gives a THD of 5.33%, which is reduced to 4.66% by employing the HD-LADRC, indicating an improved decoupling between the converters working in parallel with the proposed control scheme.

Highly active and stable oxygen electrode PrBaCo2O5+δ-Ba2CoWO6 enabled by In Situ formed misfit dislocation interface for reversible solid oxide cell

The energy conversion efficiency and durability of the reversible solid oxide cell (RSOC) is restricted by the development of highly active and stable oxygen electrode. Herein, an in-situ formed composite PrBaCo2O5+δ-Ba2CoWO6 oxygen electrode is proposed, which consists of a highly active A-site double perovskite (A-DP) phase and a stable B-site double perovskite (B-DP) phase. Misfit dislocation interface is formed between these two phases, exerting lattice tensile stress on the A-DP phase, which enhances catalytic activity and inhibits Ba segregation. Additionally, the B-DP phase suppresses lattice expansion of A-DP phase through the dislocation interface, thereby improving thermo-mechanical stability. Consequently, the composite electrode demonstrates a low polarization resistance of 0.056 Ω cm2 at 650 °C, impressive stability at 650 °C for 500 h in symmetrical cell tests, and excellent thermal-mechanical stability under 29 thermal cycles. A maximum power density of 0.75 W cm−2 and an electrolysis current density of 0.84 A cm−2 at 1.3 V were achieved at 650 °C by the composite electrode on a 260 μm-electrolyte supported cell configuration, which surpass most of the reported oxygen electrode materials. Furthermore, the cell exhibits excellent operational stability, with low degradation rates of 0.49 × 10−1 mV h−1 and 1.5 × 10−1 mV h−1 in fuel cell and electrolysis cell modes, respectively. This work offers an effective method for designing highly active and stable oxygen electrodes for RSOCs.

Development of a high-yield compact D-D neutron generator

An improved high-yield compact D-D neutron generator has been developed for active neutron non-destructive interrogation at Lanzhou University in China. The generator has been meticulously designed based on the magnetic field distribution of the duoplasmatron ion source, the electric field distribution of the beam extraction acceleration system, beam transport, and target cooling system. The performance characteristics of the generator were measured under different deuterium beam energies and beam intensities. The experimental results indicated that the D-D neutron yield reached 1×109 n/s with the deuterium beam parameter of 210 keV/6.0 mA. The operational stability of the generator was assessed for 150 minutes, and the test results show that the generator has better stability in operation. This generator has potential applications in neutron radiography, active interrogation of special nuclear materials, and neutron activation analysis.

Ruddlesden-Popper perovskite anode with high sulfur tolerance and electrochemical activity for solid oxide fuel cells

Solid oxide fuel cells (SOFCs) are regarded as attractive electrochemical energy conversion devices owing to their exceptional efficiencies and superb fuel flexibility. However, their widespread implementations are remarkably restricted by the inferior sulfur tolerance of state-of-the-art nickel-based cermet anodes under practical conditions. Herein, a layered NaLaTiO4 (NLTO) perovskite oxide with Ruddlesden-Popper structure is designed as a new anode for SOFCs operating on sulfur-containing fuels. After impregnating NLTO into a samaria-doped ceria (SDC) scaffold, such impregnated nanocomposite anode exhibits high electrochemical activity, sulfur tolerance and stability in H2S-containing fuels due to the polar layered structure, abundant oxygen vacancies, superior surface basicity and water storage capability, leading to the efficient removal of the deposited/adsorbed sulfur on the surface of this nanocomposite anode. The electrochemical activity of the NLTO-based composite anode for fuel oxidation is further improved by adding nickel nanoparticles through impregnation, showing enhanced power outputs and considerable operational stability in H2S-containing fuels. This study provides a new, high-performing and sulfur-resistant anode for SOFCs, which may promote the commercialization of this technology.

Enhancing nutrient water recovery: An integrated electrodialysis – Forward osmosis approach for reduced energy consumption and membrane fouling

The concept of combining electrodialysis (ED) and forward osmosis (FO) was previously introduced and proven effective in recovering nutrients and clean water from anaerobic effluents to produce safe liquid fertilizer. In this study, a novel and improved EDFO configuration (iEDFO) was proposed by merging the ED diluate with the FO feed solution and the ED concentrate with the FO draw solution, thus overcoming concentration limitations and fouling challenges inherent in traditional ED processes. Experimental results demonstrated significant improvements in performance, including up to 54 % and 43 % reductions in operation time and 21 % and 25 % energy savings for synthetic and real liquid digestate, respectively. These enhancements were attributed to altered ionic composition within the ED process, leading to higher, more stable current density and reduced ion back diffusion. Unlike conventional ED-only systems, the iEDFO configuration enabled continuous operation without requiring larger membrane areas or variable operational conditions. Additionally, the iEDFO configuration benefited from (1) reduced membrane fouling, and (2) decreased transport of organic contaminants across the anion exchange membranes (AEMs) into the ED concentrate product. Overall, the iEDFO system provides significant advantages in efficiency, energy savings, and operational stability, making it a highly effective and sustainable solution for resource recovery from liquid waste.

Solids retention time (SRT) control in the co-treatment of leachate with domestic sewage in aerobic granular sludge systems: Impacts on system performance, operational stability, and bioresource production

This study investigates the co-treatment of leachate and domestic sewage in municipal wastewater treatment plants using aerobic granular sludge (AGS) systems, focusing on granule formation, system stability, and resource production in two units (R1 and R2). In R2, solids retention time (SRT) was controlled between 10 and 25 days, while R1 maintained approximately 9 days. The results show that low leachate proportions (5 %) did not affect system performance or stability. However, increasing the leachate to 10 % reduced the structural stability of extracellular polymeric substances (EPS), leading to a significant decrease in alginate-like exopolysaccharides (ALE) production in R1 (216 mgALE/gVSS) and R2 (125 mgALE/gVSS). Principal component analysis revealed that SRT was crucial for optimizing biopolymer synthesis. Furthermore, SRT control in R2 improved filamentous control, biomass retention, and total nitrogen removal. Thus, selective biomass discharge is essential for maintaining granule stability, enhancing treatment efficiency, and supporting resource production.