Control Engineering Research Articles

Physical Strategies for Geometric Control of Transition Metal Dichalcogenide Atomic Layers by Chemical Vapor Deposition

AbstractThe diverse morphologies of 2D transition metal dichalcogenides (2D TMDs) motivate their broad potential applications in the next generation of electronic, optical, and catalytic technologies. It is advantageous to develop controllable growth techniques that afford versatility through direct manipulation of the growth parameters. A fundamental understanding of the physical mechanisms driving various growth modes is crucial for achieving the process precision necessary for obtaining reproducible morphologies in 2D TMDs. Thermodynamic and kinetic considerations are two key physical strategies. Thermodynamic strategies mainly involve the manipulation of parameters like temperature and the chemical potential of precursors to ensure the thermostability of various morphologies. Conversely, kinetic strategies, focusing on the factors, like precursor diffusion, adsorption, and desorption during the growth, also enable atomic‐level kinetics control of the resulting morphologies. Often, an interplay of both mechanisms drives the growth of a particular morphology. This review aims to provide an updated guidance for exploiting these physical strategies in the versatile technique of chemical vapor deposition. The opportunities for further exploring the control of these physical mechanisms are discussed through recent examples with an eye on unlocking the untapped potential of 2D TMDs in areas such as phase engineering and shape control for advanced applications.

Defect-mediated Fermi level modulation boosting photo-activity of spatially-ordered S-scheme heterojunction

Spatially-ordered S-scheme photocatalysts are intriguing due to their enhanced light harvesting, spatially isolated redox sites, and strong redox abilities. Nonetheless, heightening the performance of S-scheme photocatalysts via controllable defect engineering is still challenging to now. In this work, multi-armed MoSe2/CdS S-scheme heterojunction with intimate Mo-S bond coupling and adjustable Se vacancies (VSe) and Mo5+ concentrations was constructed, which consisted of few- or even single-layered MoSe2 growing on the {11–20} facets of wurtzite CdS arms. The S-scheme charge transmission mechanism of MoSe2/CdS heterojunction was validated by density functional theory calculation combined with in situ photo-irradiated X-ray photoelectron spectroscopy, surface photovoltage, and radical measurements. Moreover, the Fermi level gap between CdS and MoSe2 was enlarged by regulating the contents of donor (VSe) and acceptor (Mo5+) impurities with synthesis temperature, which strengthens the built-in electric field and carriers transfer driving force of MoSe2/CdS composites, contributing to an outstanding H2 evolution activity of 52.62 mmol·g−1·h−1 (corresponding to an apparent quantum efficiency of 34.8 % at 400 nm) under visible-light irradiation (λ > 400 nm), 25.8 times that of Pt-loaded CdS counterpart and a substantial amount of reported CdS-containing photocatalysts. Our study results are anticipated to facilitate the rational design of advanced semiconductor nanostructures for efficient solar conversion and utilization.

Jet engines, wind turbines, and AI: community reactions to new sounds

When jet engine-powered commercial aircraft started flying in and out of airports in the mid-20th century, surrounding communities-often in rural areas-were exposed to unprecedented sound levels. A straight line can be drawn from the reactions of those communities to today's Federal Aviation Administration (FAA) airport acoustical requirements. Community reactions to utility-scale wind energy facilities in the late 20th and early 21st centuries led to a bevy of local legislation around the United States, some of which has been insightful and helpful. More recently, society's ever-increasing demand for bits and bytes is introducing suburban areas to data centers-campuses of multi-story buildings requiring access to high volumes of cool air, fast Internet connections, and megawatts of electricity. Community reactions to the resulting environmental sound levels are again driving regulation and legislation. In all these cases, community reactions have driven the narrative. Instead of responding to community reactions, the noise control engineering community and their clients could be more proactive-the professionals could lead the narrative. Ideas about how to achieve this level of proactivity are discussed.

An appreciation of the research of George Maling

No single individual has been more important to the formation, direction, and continuing work of the Institute of Noise Control Engineering (INCE/USA) than Dr. George Maling. Not only has he significantly shaped the trajectory of INCE-USA, but he contributed greatly to the field of acoustics and noise control. This paper will provide a concise overview of Dr. Maling's research contributions and numerous publications. Specifically, his contributions on modeling acoustic sources, characterization of air moving devices, and reverberation room simulation and measurements will be reviewed.

Thrust online fusion estimation of high-flow dual variable cycle engine

For the aeroengines, thrust is a crucial performance parameter which is closely related to the mission accessibility. Accurate thrust control is conducive to excavate the potential of the variable cycle engine (VCE) in different operation modes, which meets the requirements of future engine control system. However, the thrust is unmeasured in flight. Besides, the traditional thrust estimation method is difficult to meet the wide-area thrust control requirements due to the strong nonlinearity and large flight envelope for a neoconfiguration VCE of the high-flow triple-bypass, named high-flow dual variable cycle engine (HDVCE). This paper proposes a novel online fusion thrust estimation method mainly under single operation mode for the HDVCE. The problem of individual engine differences is also focused, and the combination of model and data-driven is to generate the thrust estimation with fusion strategy. At first, a multi-combustion chamber coupled dynamic model is established for the HDVCE, and an adaptive network is used for model optimization to improve the model accuracy. On this basis, an EKF-based thrust estimator is built. Secondly, a data-driven thrust estimator is pre-trained by a stacked autoencoder (SAE) and then tuned by back propagation (BP) neural network. Subsequently, the thrust integration is incorporated based on estimation results from the EKF-based and data-driven one using Euclidean distance fusion strategy. Simulation results show that the fusion estimation method proposed in this paper, on the one hand, reduces the effect of model instability on EKF. On the other hand, it ensures the estimation accuracy of SAE-BP far from the training point. The comparisons also reveal that the fusion one produces more than 97% in thrust estimation accuracy and is better than the remaining ones, which is promising for thrust control applications.

Leading the Lorenz 63 system toward the prescribed regime by model predictive control coupled with data assimilation

Abstract. Recently, concerns have been growing about the intensification and increase in extreme weather events, including torrential rainfall and typhoons. For mitigating the damage caused by weather-induced disasters, recent studies have started developing weather control technologies to lead the weather to a desirable direction with feasible manipulations. This study proposes introducing the model predictive control (MPC), an advanced control method explored in control engineering, into the framework of the control simulation experiment (CSE). In contrast to previous CSE studies, the proposed method explicitly considers physical constraints, such as the maximum allowable manipulations, within the cost function of the MPC. As the first step toward applying the MPC to real weather control, this study performed a series of MPC experiments with the Lorenz 63 model. Our results showed that the Lorenz 63 system can be led to the positive regime with control inputs determined by the MPC. Furthermore, the MPC significantly reduced necessary forecast length compared to earlier CSE studies. It was beneficial to select a member that showed a larger regime shift for the initial state when dealing with uncertainty in initial states.

Molten salt defect engineering regulation of Bi4TaO8Cl perovskite structure for boosting photo-Fenton degradation of antibiotics

Defect engineering offers a feasible avenue to ameliorate the photocatalytic activities of semiconductors, but the traditional preparation processes for introducing the defects would destroy the pristine morphology of the materials. Herein, a controllable defect engineering on CeO2 nanodots loaded Bi4TaO8Cl perovskite nanosheets was approached to synthesize well-defined CeO2/Bi4TaO8Cl (CE-BTC) heterojunction with stable oxygen vacancies (OVs) via a molten-salt-mediated strategy. Due to the coexistence of OVs and Ce4+/Ce3+ redox couple, the photo-Fenton degradation rate of ofloxacin by optimal CE-BTC heterojunction (0.09610 min−1) was 7.78 and 4.98 times higher than that by individual Bi4TaO8Cl and CeO2, respectively. Moreover, the CE-BTC also exhibited excellent degradation performance towards other antibiotics including norfloxacin, ciprofloxacin, tetracycline, and sulfamethoxazole, while maintaining good recyclability and stability. The high efficiency of CE-BTC was also attributed to its enhanced light-harvesting capability, low photogenerated carrier recombination, and minimal electron transfer resistance. Mechanism study indicated that ⋅OH and ⋅O2– were the dominant reactive species, whereas h+ also participated in the removal of ofloxacin with a lower contribution. This study demonstrated the enormous potential of CE-BTC heterojunction in the degradation and risk control of antibiotics, providing a promising strategy for designing highly dispersed heterojunction catalysts with surface defects.

Fractional dynamics of entropy generation in unsteady mixed convection of a reacting nanofluid over a slippery permeable plate in Darcy–Forchheimer porous medium

AbstractThis paper presents a theoretical investigation of the inherent irreversibility in unsteady fractional time derivative mixed convection of a reacting nanofluid with heat and mass transfer mechanism over a slippery permeable plate embedded in a Darcy–Forchheimer porous medium. The model fractional partial differential equations are obtained based on conservation laws and numerically solved using the implicit finite difference scheme. The study displays and discusses the effects of various emerging parameters on the overall flow structure, such as velocity profiles, temperature distribution, nanoparticles concentration profiles, skin friction, Nusselt number, Sherwood number, entropy generation rate, and Bejan number. It was found that an increase in dimensionless time and fractional parameters leads to a decrease in both the entropy generation rate and the Bejan number. The study revealed that fractional order derivatives can capture intrinsic memory effects, non‐local behaviour, and anomalous diffusion in the nanofluid flow process. This can ultimately lead to better engineering system design and control.

An Investigation of Water Resource Management in the Beverage Industry

According to studies, industrial water use comprises production processes, auxiliary processes, kitchen use, and outdoor use. Reducing industrial water use is dependent on the implementation of administrative, engineering, mechanical, and human controls. The objectives of this research were to assess the water use of a Soft Drink Plant; determine the water use ratio for a two-year period; and determine the plant’s compliance with local and international regulations for wastewater discharge. We also determined the level of success of implementing a water minimisation plan, whether there was an improvement in the Water Use Ratio, and compliance of the industry with local and international discharge regulations. The sequential transformative strategy was used to collect and analyse data so as to ascertain water usage and disposal, and a semi-structured interview was conducted to validate the non-existence of heavy metals in the wastewater discharged from the soft drink plant. The Soft Drink Plant’s Water Minimisation Plan 2013-2016 achieved a high level of success overall, with 74.42% of the activities implemented by the assigned completion dates. However, three of the five measures implemented recorded low levels of success. Paired sample t-tests revealed statistically significant differences in the water use ratio obtained for the periods 2013-2014, 2014-2015, and 2013-2015, although the differences were relatively small (t (df)=2.242, p=0.047; t (df)=2.592, p=0.025; and t (df)=6.250, p=0.000) for the respective periods. Six of the eleven tested parameters were statistically different when compared to the Coca-Cola Operating Requirements and Environmental Protection Agency standards, indicating a high variation in effluent discharge.

Evaluation of NOx and PN Emission in Relation to Actuator Control.

This study aimed to investigate the interrelationships between key harmful emission components, nitrogen oxides (NOx), and particulate numbers (PNs) in diesel engine exhaust and the control actuators of diesel engines. This research involved conducting a series of experiments under fixed parameters within an engine brake laboratory environment to elucidate these correlations. The objectives of this study were to conduct a comprehensive review of the relevant emissions technology literature and a comparative assessment of particle measurement methods based on dilution ratios and develop innovative aerosol preparation principles tailored to condensation particle measurement. Additionally, this research involved designing and implementing an aerosol preparation unit based on the newly developed principles, along with the creation of test cell control programs using the AVL PUMA Open TST editor interface and Visual Basic. Furthermore, this study was concerned with conducting evaluations of fixed-parameter engine dynamometer tests to explore the functional relationships between the emission of 10/23 nm particles, NOx emissions, common rail pressure variations, and exhaust gas recirculation levels. This study aimed to enhance the understanding of diesel engine emissions dynamics and contribute valuable insights for developing more efficient and environmentally friendly engine control strategies.

Simulation and analysis of dam leakage inlet detection based on pseudo-flow field method

Seepage hazards in dams remain a critical issue in flood control engineering. The pseudo-flow field method has shown high efficacy in detecting seepage points within dam structures. This paper delves into the core characteristics of the pseudo-flow field method, aiming to accelerate its detection speed in practical engineering contexts. By employing the Laplace equation for electric current, we established a numerical model to simulate the method's application in real-world scenarios. The simulation reveals the key characteristics of potential and current density distributions along measuring lines within the pseudo-flow field. Both horizontal and vertical measuring lines show a peak distribution of current density and potential near the seepage point, gradually diminishing towards the periphery. Conversely, vertical measuring lines further from the seepage point exhibit minimal changes, presenting a uniform distribution of current density and potential. The results confirm that the pseudo-flow field method can effectively detect seepage locations and that strategic placement of measuring lines can markedly improve detection speed.

A Review of Autonomous Berthing Technology for Ships

Autonomous berthing technology is a crucial engineering control problem within the ship intelligence system, encompassing a series of complex operations and technologies. Firstly, this paper analyses the research on autonomous berthing technology from a bibliometric point of view in order to obtain an overview of its past and present development and to outline the importance of this technology. Secondly, a literature review is conducted on each of the four aspects of autonomous berthing technology, namely sensing technology, berthing type, control method, and evaluation method, which can help to quickly understand the main aspects of this technology. Thirdly, the ship-assisting technologies needed to achieve autonomous berthing are discussed and analysed from six aspects: dynamic collision avoidance, path planning, path tracking, heading control, tug assistance, and shore-based systems. Finally, the challenges faced by the ship autonomous berthing technology on the way of development are summarised, and future development is projected. This paper aims to provide a more comprehensive perspective for analysing and researching ship autonomous berthing technology.

Applying fischer tropsch and its pentanol blends into an aviation compression ignition engine for PM emissions control

The aviation industry is recovering from COVID-19 to regain rapid growth at an increasing rate of over 5 % annually. Aviation compression ignition (CI) engines attributed to their economic fuel consumption and adorable reliability, have been widely utilized in the general aviation (GA) industry. To fill in the knowledge gap of the compatibility of Fischer Tropsch (FT) blended with long-chain oxygenated fuel applied into the aviation engines, this research focuses on analyzing the combustion performance and particle matter (PM) emissions of an aviation CI engine by burning FT alternative fuel and its pentanol blends (FT80P20 - 80 % FT + 20 % pentanol), in comparison with baseline diesel/pentanol-diesel blends (D80P20 - 80 % diesel + 20 % pentanol). It was found that FT80P20 significantly increases the indicated thermal efficiency (ITE) by 6.5 %, and remarkably decreases the indicated specific fuel consumption (ISFC) by 12 % in contrast to neat diesel at high load (8.5 bar IMEP), which is due to better homogeneous charge that alternates heterogeneous combustion. Moreover, the PM size-resolved number distributions of emissions were characterized. It was observed that the integrated PM emissions from diesel were predominant (∼1.4 × 1014 #/kg∙fuel), while those from FT80P20 were significantly reduced by nearly 85 % (∼0.2 × 1014 #/kg∙fuel). Concurrently, the particulate geometric mean diameter (GMD) were decreased apparently from 80 nm to 35 nm correspondingly. The research findings reveal that “main diffusion combustion” was predominant as burning diesel, while “main premixed combustion” was prominent as using FT80P20, which has a promising impact on effective engine-work promotion with superior PM mitigation.

Improving load frequency controller tuning with rat swarm optimization and porpoising feature detection for enhanced power system stability

Load frequency control (LFC) plays a critical role in ensuring the reliable and stable operation of power plants and maintaining a quality power supply to consumers. In control engineering, an oscillatory behavior exhibited by a system in response to control actions is referred to as “Porpoising”. This article focused on investigating the causes of the porpoising phenomenon in the context of LFC. This paper introduces a novel methodology for enhancing the performance of load frequency controllers in power systems by employing rat swarm optimization (RSO) for tuning and detecting the porpoising feature to ensure stability. The study focuses on a single-area thermal power generating station (TPGS) subjected to a 1% load demand change, employing MATLAB simulations for analysis. The proposed RSO-based PID controller is compared against traditional methods such as the firefly algorithm (FFA) and Ziegler-Nichols (ZN) technique. Results indicate that the RSO-based PID controller exhibits superior performance, achieving zero frequency error, reduced negative peak overshoot, and faster settling time compared to other methods. Furthermore, the paper investigates the porpoising phenomenon in PID controllers, analyzing the location of poles in the s-plane, damping ratio, and control actions. The RSO-based PID controller demonstrates enhanced stability and resistance to porpoising, making it a promising solution for power system control. Future research will focus on real-time implementation and broader applications across different control systems.

Vacancy‐Rich Ternary Iron Phosphoselenide Multicavity Nanorods: A Highly Reversible and Fast Anode for Sodium‐Ion Batteries

AbstractThe significance of exploring optimal electrode materials cannot be overstated, particularly in mitigating the critical issues posed by sluggish redox kinetics, significant volume variations, and severe structural collapse resulting from the insertion and extraction of sodium ions. These efforts are crucial for enhancing the longevity and rapid charging capabilities of sodium‐ion batteries (SIBs). Herein, a defect engineering strategy for the in situ encapsulation of single‐phase ternary iron phosphoselenide into porous carbon by robust chemical bonds with the formation of rod‐like multicavity nanohybrids (FePSe3@C) is presented. The incorporation of Se atom not only modulates the electronic structure of the central metal Fe atom and enhances the intrinsic electrical conductivity, but also generates numerous additional reaction sites and accelerates the reaction kinetics of FePSe3@C, as corroborated by theoretical calculations and kinetic analysis. Notably, the FePSe3@C demonstrates an outstanding rate capability of 321.7 mAh g−1 even at 20 A g−1 and long cycling stability over 1000 cycles. The sodium‐ion full cell, pairing the FePSe3@C anode with the Na3V2(PO4)3@C cathode, exhibits a remarkable energy density of 202 Wh kg−1, demonstrating its practical applicability. This work provides a controllable defect and morphology engineering strategy to construct advanced materials with fast charge transfer for high‐power/energy SIBs.

Highly parallel production of designer organoids by mosaic patterning of progenitors

Organoids derived from human stem cells are a promising approach for disease modeling, regenerative medicine, and fundamental research. However, organoid variability and limited control over morphological outcomes remain as challenges. One open question is the extent to which engineering control over culture conditions can guide organoids to specific compositions. Here, we extend a DNA "velcro" cell patterning approach, precisely controlling the number and ratio of human induced pluripotent stem cell-derived progenitors contributing to nephron progenitor (NP) organoids and mosaic NP/ureteric bud (UB) tip cell organoids within arrays of microwells. We demonstrate long-term control over organoid size and morphology, decoupled from geometric constraints. We then show emergent trends in organoid tissue proportions that depend on initial progenitor cell composition. These include higher nephron and stromal cell representation in mosaic NP/UB organoids vs. NP-only organoids and a "goldilocks" initial cell ratio in mosaic organoids that optimizes the formation of proximal tubule structures.

Freeze-thaw effects on pore structure of clay by 3D X-ray computed tomography and mercury intrusion porosimetry

Thaw settlement of soils is a comprehensive reflection of multiscale pore changes induced by freeze-thaw (F-T). In this study, three-dimensional (3D) X-ray computed tomography (CT) tests were utilized to investigate alterations in the macropore and mesopore structures, while mercury intrusion porosimetry (MIP) tests were used to examine the micropore structure in clay due to F-T influenced by different freezing temperatures without water supply. The maximum increase in CT transverse-sectional porosity after F-T can be used to identify where ice lenses formed most abundantly in the clay after thawing, and the diameter and horizontal orientation of the macropores exhibit the most significant increase after thawing. As the freezing temperature decreases, the location becomes farther from the cold end. Macropores are significantly more affected by F-T compared to mesopores, and changes in macropore porosity and diameter can be attributed to moisture migration and freezing shrinkage, with lower freezing temperatures amplifying the influence of freezing shrinkage and weakening the impact of moisture migration. Considering the small size of samples, the MIP porosity was defined to analyze the effects of F-T on the micropores. Compared to the CT volumeratic porosity, the influence of F-T on micropore porosity is less significant. As the freezing temperature decreases, the changes in micropore diameter become smaller. Overall, the lower the freezing temperature, the smaller the changes in macropores, mesopores and micropores. Lastly, a method is proposed for predicting the mass porosity based on the CT volumetric porosity and MIP porosity. This study demonstrates that changes in soil mass porosity reflect a comprehensive representation of multiscale pore variations and provides important theoretical support for thaw settlement control in artificial freezing engineering.

Overview of the Prevalence and Contributing Factors for Occupational Noise-Induced Hearing Loss (NIHL) in Malaysia

INTRODUCTION: This manuscript aims to provide a synopsis of the current situation surrounding noise exposure at work and the risk of noise-induced hearing loss (NIHL) in Malaysia. NIHL is an occupational illness that affects most many people and can be prevented in many countries in the world. The production and agriculture businesses and the extraction of natural resources and urban traffic all contribute to ambient noise levels. Working in a noisy environment is the main occupational risk factor for adult-onset hearing loss. In this study, we investigate the prevalence of NIHL across different industries, as well as research publication trends on NIHL. MATERIAL AND METHODS: Conducted thorough several online databases, like Science Direct, Web of Science, and Google Scholar, for related research that had already been published. The review phases were carried out according to the recommendations laid out by the preferred reporting items for systematic reviews. A set of criteria was developed for selecting relevant studies. RESULTS: The prevalence of NIHL among workers in Malaysia, varies across different industries and has been reported to range from 5.0% to 82.6%. NIHL has multiple contributing factors, including noise intensity, long-term exposure to daily noise, hearing protection devices and age. A review of these studies found varying percentages of individuals affected by each contributing factor. CONCLUSION: Occupational NIHL is a preventable health risk for workers across industries. Employers must adopt engineering and administrative controls (education and training) and provide personal hearing protectors to protect workers from noise.

Event-Triggered Adaptive Bipartite Secure Consensus Asymptotic Tracking Control for Nonlinear MASs Subject to DoS Attacks

This paper proposes an adaptive bipartite secure consensus asymptotic tracking control scheme based on event-triggered strategy for the nonlinear multi-agent systems (MASs) under denial-of-service (DoS) attacks. First, by incorporating the concept of shortest path into the hierarchical algorithm, the bipartite consensus control problem in the presence of unbalanced communication topology is successfully addressed. Further, an anti-attack bipartite control strategy by designing the improved forms of the tracking errors and virtual controllers is proposed under DoS attacks. Then, a modified event-triggered mechanism based on the relative threshold strategy is proposed, which can ensure that the bipartite consensus tracking errors converge to zero asymptotically by utilizing the Barbalat’s Lemma. Under the Lyapunov stability theory, it is guaranteed that the outputs of all agents can reach agreement with an identical magnitude but opposite signs and all the signals of the closed-loop MASs are bounded. Finally, the simulation results on the model of damping pendulums are given to verify the efficiency of the proposed secure controller. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —In this paper, the adaptive bipartite secure consensus asymptotic tracking control problem is considered for nonlinear MASs subject to DoS attacks, whose models can describe many critical applications, such as bidirectional formation of unmanned vehicles and robots. The research on the secure tracking control problem will be rather complicated yet challenging if the DoS attacks of the communication channels are taken into account in the insecure complex network environment. In addition, the event-triggered mechanism is used to reduce the usage of communication resources, which makes the proposed control scheme more easier to implement and more friendly for control engineers.

Resonancelike emergence of chaos in complex networks of damped-driven nonlinear systems.

Characterizing the emergence of chaotic dynamics of complex networks is an essential task in nonlinear science with potential important applications in many fields such as neural control engineering, microgrid technologies, and ecological networks. Here, we solve a critical outstanding problem in this multidisciplinary research field: the emergence and persistence of spatiotemporal chaos in complex networks of damped-driven nonlinear oscillators in the significant weak-coupling regime, while they exhibit regular behavior when uncoupled. By developing a comprehensive theory with the aid of standard analytical methods, a hierarchy of lower-dimensional effective models, and extensive numerical simulations, we uncover and characterize the basic physical mechanisms concerning both heterogeneity-induced and impulse-induced emergence, enhancement, and suppression of chaos in starlike and scale-free networks of periodically driven, dissipative nonlinear oscillators.