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En este artículo se analiza una red de distribución urbana de 23 kV típica de la zona central de México. El objetivo es determinar la distancia máxima de separación entre apartarrayos de línea que permita reducir las salidas de los circuitos de distribución por descargas atmosféricas directas e indirectas. Con base en las características eléctricas, ambientales, ceráunicas y geográficas de la zona, niveles de cortocircuito y las sobretensiones provocadas por maniobras rutinarias, se selecciona el apartarrayos siempre con el principal objetivo de determinar su espaciamiento adecuado sobre la línea para que éste funcione apropiadamente. La investigación se lleva a cabo con la ayuda del software llamado Alternative Transients Program (ATP) donde se realiza el cálculo de los parámetros de la línea utilizando el modelo de K.C. Lee, las sobretensiones transitorias por onda viajera y por conexión de capacitores también son simuladas. La motivación de este trabajo consiste principalmente en contar con un mayor sustento teórico y técnico (actualmente escueto) para determinar el espaciamiento entre apartarrayos de la red de distribución considerada y así aumentar la calidad del suministro eléctrico de la zona.

Esta investigación presenta la simulación de las sobretensiones ocurridas durante una maniobra de mantenimiento en un compensador estático de potencia reactiva de 230 kV. El incorrecto funcionamiento de un interruptor de potencia causa una falla catastrófica que incluye la explosión y el incendio del equipo. La Información obtenida de investigaciones previas, donde se analizan los estados estable y transitorio del compensador, no toma en cuenta la combinación del comportamiento del compensador y la fallida operación de los medios de desconexión. La incorrecta apertura de uno de los polos del interruptor de potencia del compensador provoca sobretensiones interesantes las cuales están relacionadas con las componentes armónicas de tensión y corriente generadas por un elemento clave de la falla: el reactor controlado por tiristores. En este trabajo se utiliza el Software Alternative Transients Program (ATP) para modelar el compensador y obtener el cálculo de las sobretensiones transitorias. Se analizan las frecuencias naturales y el espectro armónico de las señales manejadas por el compensador. Con la ayuda de una videograbación se muestran imágenes reales de los arcos eléctricos generados debido a las sobretensiones. Este estudio se realiza por primera vez en este compensador estático y la información resultante es de mucha utilidad futura para el diseño eléctrico y la planificación de la operación de las redes de potencia.

The present study is devoted to the monitoring of the performance of AA2024-T3 specimens, after the formation of Anodic Aluminum Oxide (AAO) layer and/or deposition of a Ceruim Conversion Coating (CeCC), obtained at 20°C and 50°C, respectively. Although both methods are well described in the literature, there is no sufficient information regarding the effect of their combination on their behaviour in corrosive media. The performance of the respective specimens was elucidated after 24 h of exposure to 3.5 % NaCl model corrosive medium (MCM) by means of Electrochemical Impedance Spectroscopy (EIS) and acquisition of Potentiodynamic Scanning (PDS) curves. Since the combined AAO/CeCC coating primers revealed superior barrier properties, the respective specimens were subjected to long-term corrosion tests of up to 672 h of exposure to the MCM to evaluate their durability. The results revealed the synergistic effect of the combination of the surface treatment procedures on effective corrosion mitigation. [ABSTRACT FROM AUTHOR]

Flexible and stretchable microdevices incorporate highly deformable structures, facilitating precise functionality at the micro- and millimetre scale. Flexible microdevices have showcased extensive utility in the fields of biomedicine, microfluidics, and soft robotics. Actuation plays a critical role in transforming energy between different forms, ensuring the effective operation of devices. However, when it comes to actuating flexible microdevices at the small millimetre or even microscale, translating actuation mechanisms from conventional rigid large-scale devices is not straightforward. The recent development of actuation mechanisms leverages the benefits of device flexibility, particularly in transforming conventional actuation concepts into more efficient approaches for flexible devices. Despite many reviews on soft robotics, flexible electronics, and flexible microfluidics, a specific and systematic review of the actuation mechanisms for flexible and stretchable microdevices is still lacking. Therefore, the present review aims to address this gap by providing a comprehensive overview of state-of-the-art actuation mechanisms for flexible and stretchable microdevices. We elaborate on the different actuation mechanisms based on fluid pressure, electric, magnetic, mechanical, and chemical sources, thoroughly examining and comparing the structure designs, characteristics, performance, advantages, and drawbacks of these diverse actuation mechanisms. Furthermore, the review explores the pivotal role of materials and fabrication techniques in the development of flexible and stretchable microdevices. Finally, we summarise the applications of these devices in biomedicine and soft robotics and provide perspectives on current and future research. [ABSTRACT FROM AUTHOR]

The work presents the effects of hydrostatic pressure and temperature on the electronic spectra as well as on the optical responses of parabolically shaped asymmetric triple quantum wells formed between the GaAs/Al0.3Ga0.7As heterostructures. The electronic structure of the configuration is obtained by iteratively solving the Schrödinger equation within effective mass and envelope wave function approximations. Optical properties are calculated within the compact density matrix approach framework. The results in this study show that increasing hydrostatic pressure field leads to small redshifts on the total optical absorption coefficient, relative refractive index change, nonlinear optical correction, and second and third harmonic generations, while temperature augmentation causes significant redshifts in these optical properties. [ABSTRACT FROM AUTHOR]

The current research presents results following corrosion tests, performed on combined anodic alumina/cerium conversion coatings (Al2 O3 /CeCC), thermally sealed for 15 min at 100°C either in boiling water or in hot-air medium. The coatings were formed on AA2024-T3 aircraft alloy substrates, at the optimum conditions of anodization and cerium conversion coating deposition, described in previous works. Prior to the corrosion tests, both the color characteristics and wetting ability of the combined films were evaluated. The corrosion protective properties of the sealed films were assessed by means of Electrochemical Impedance Spectroscopy (EIS) and Potentiodynamic Polarization (PDP). The measurements were performed after 672 hours of exposure to a 5 % NaCl model corrosive medium (MCM). Additional long term (up to 1344 hours of exposure) durability tests were then performed under the same conditions for the samples and superior performance was established. The electrochemical measurements were conducted regularly, once a week. Low- and high-resolution Scanning Electron Microscopy (SEM) studies were performed on selected samples. The experimental results have shown that the sealing procedure in an aqueous environment enhances the corrosion protective ability and durability of the coating, probably due to formation of a hydrate layers, that suppresses the access of corrosive species to the surface of the substrate. This inference was additionally confirmed by the subsequent chemical analysis by means of X-Ray Photoelectron Spectroscopy (XPS). The results acquired have also shown that the incorporated Ce is predominantly in the form of Ce(IV)-oxides/hydroxides and after the thermal treatment almost entirely consists of cerium. [ABSTRACT FROM AUTHOR]

In the present analysis, a novel four-mode solar dryer was developed and tested for the drying of Garcinia pedunculata. The four combinations considered were indirect-mode solar dryer without storage (ID-WOS), mixed-mode solar dryer without storage (MX-WOS), indirect-mode solar dryer with storage (ID-WS), and mixed-mode solar dryer with storage (MX-WS). The feature of this dryer that sets it apart is its capability to convert the drying cabinet into various modes simply by sliding the walls of the four sides of the cabinet. The storage system is made space efficient, by filling the gravel up to the surface of the absorber plate inside the solar air collector. For ID-WOS, MX-WOS, ID-WS, and MX-WS, respectively, the drying durations were 30 h, 25 h, 28 h, and 8 h, and the drying efficiencies were 18.55%, 24.03%, 20.32%, and 29.94%. In ID-WOS, MX-WOS, ID-WS, and MX-WS, the average exergy efficiency was determined as 47.08%, 65.10%, 52.46%, and 68.07%, respectively. Environmental impact was studied for all four cases. The energy payback periods for ID-WOS, MX-WOS, ID-WS, and MX-WS were 1.47, 1.61, 1.48, and 1.62 years, respectively. The study indicated that MX-WS outperformed the other three configurations in all aspects. [ABSTRACT FROM AUTHOR]

In this paper, we propose a cellular automaton model to investigate the traffic flow characteristics in the traffic circle system with adaptive traffic lights control. The traffic flow in the circulating lane was evaluated and depending on it the traffic lights lit red in the entry lanes to reduce the coming traffic. The density and the satisfaction rate were used as feedback to control the traffic flow in the circulating lane. It is found that both parameters (i.e. the density and the satisfaction rate in the circulating lane), if they are used as a criterion to control the coming traffic from entry lanes, promote the throughput in the traffic circle system. Traffic flow for the traffic circle system without using the traffic lights was investigated. In this case, we find that the traffic flow in the system is characterized by three phases, namely, gridlock, congestion, and free flow. The gridlock phase is predominant over the other phases. Furthermore, with the use of the adaptive traffic lights, the gridlock phase has vanished and the maximum current, jammed, and congestion phases take place. The density criterion shows good performance as compared with the satisfaction rate criterion in terms of the lengths of the red cycle. The capacity is also investigated. The space-time configurations were given to understand the microscopic interaction between vehicles. [ABSTRACT FROM AUTHOR]

In this paper, we study the probability of car accidents in the modified Nagel–Schreckenberg (mNaSch) under the periodic boundary condition. In order to understand the quality of interaction between vehicles in each phase of the mNaSch, the velocity correlation coefficients were investigated. The effect of the evacuation of damaged vehicles was also studied. The fundamental diagram of the system is constructed in both cases with and without the evacuation. We found that the synchronized phases in the mNaSch are manifested into two aspects. In the first phase, the velocity correlation coefficients are zero where all vehicles move at the same speed. Hence, in the other phase, the speed of vehicles shows a synchronization as the form of clusters of moving vehicles where two speeds predominate simultaneously and the velocity correlation coefficients are higher. In addition, the car accidents in the modified mNaSch depend strongly on the initial configuration especially, if we consider those car accidents really happening in the system. The evacuation of damaged vehicles enhances the traffic situation and qualitatively changes the traffic phases in the mNaSch. [ABSTRACT FROM AUTHOR]

In this paper, we propose a cellular automaton model to simulate traffic flow controlled by a series of traffic lights. The synchronized traffic light and the green wave light strategies were investigated. The spatiotemporal diagrams, energy dissipation, and CO2 emission of the system were presented. Our simulations are conducted to clarify the difference between both strategies and their effects on the traffic flow and the CO2 emission. We found that the traffic flow depends mainly on the strategy used for managing the traffic lights as well as on the parameters of the traffic lights, namely the cycle length, the number of traffic lights and the length of the system. The fundamental diagram has barely the same characteristics for both methods and it depends on the combination of the parameters of the system. We find that the green wave is more convenient for the management of a series of traffic lights than the synchronized control strategy in terms of throughput, especially for large-sized systems. Unlike in terms of CO2 emission and energy dissipation, both control strategies outperform each other depending on the density regions and the parameters of the system. Finally, we investigate the effect of both cycles (i.e. red and green) for the synchronized control method on the CO2 emission. It is found that the green cycle generates often a series of acceleration events that increase CO2 emission. [ABSTRACT FROM AUTHOR]

Electrical conductivity and dielectric parameters are general inherent features of materials. Controlling these characteristics through applied bias will add a new dimension to regulate the dynamic response of smart materials. Here, a fascinating electrical transport behavior is observed in topological insulator (TI) Bi 2 Te 3 nanorods, which will play a vital role in intelligent materials or devices as a unit for information reception, processing or feedback. The Bi 2 Te 3 nanorod aggregates exhibit a monotonic resistance response to voltage, with observed four-fold change of electrical conductivity in a small range electric field of 1 V mm -1 . The dielectric constant and dielectric loss of Bi 2 Te 3 nanorod composites also show strong dependences on bias voltage due to the unique electrical transport characteristics. The unique voltage-controlled electrical responses are attributed to the change of Fermi levels within the band structure of disordered TI nanorods, which are non-parallel to the applied electric field. The excellent controllable inherent characteristics through electric field endows Bi 2 Te 3 nanomaterials bright prospects for applications in smart devices and resistive random access memories., (© 2022 Wiley-VCH GmbH.)

In this paper, we proposed a model based on the connected vehicles to control the traffic flow at the intersection. To evaluate this model, we studied its impact on the flux and the probability of accidents at the intersection. On the one hand, simulation results showed that the increase in the number of connected vehicles decreases the congestion coefficient and enhances the traffic situation in the system. On the other hand, connected vehicles reduce the probability of accidents at the intersection. In this way, the vehicle intersection (central controller) communication can decrease the congestion and enhance road safety, especially in the intermediate and high traffic conditions. [ABSTRACT FROM AUTHOR]

Various feedback strategies are proposed to improve the traffic flow. However, most of these works did not take road safety into consideration. In this paper, we studied the impact of four feedback strategies on the probability of rear-end collisions ( P ac ). We proposed a new feedback strategy named Accidents Coefficient Feedback Strategy (ACFS) in which dynamic information can be generated and displayed on a board at the entrance of two-route scenario with intersection to help drivers to choose the appropriate road. This new strategy can greatly improve road safety and make the flow smooth as possible at the same time. Moreover, the impact of the intersection and boundary rates (α and β) on P ac is also studied. [ABSTRACT FROM AUTHOR]

Using the Nagel-Schreckenberg model, we investigate the flow characteristics in a traffic circle system, where the entry lanes are controlled by traffic lights operating in a fixed-time ( T ). We considered four different strategies to control traffic coming from N entry lanes. We found that depending on the strategy used, four distinct traffic phases can appear in the circulating lane of the traffic circle, namely free flow, congestion, maximum current, and gridlock. Also, we investigate the origin of the gridlock phase in both cases (i.e. with/without traffic lights). Furthermore, the lengths of queues of stopped vehicles in the entry lanes were studied. We found that the traffic flow behavior on the exit/entry lanes depends strongly on the flow characteristics at the circulating lane as well as traffic lights strategy. To improve the operation of the traffic circle system, we have studied the time delay between the traffic lights to switch where all entry lanes go red, which allowing vehicles to clear the circulating lane. [ABSTRACT FROM AUTHOR]

In this paper, we propose a stochastic cellular automata model to study the traffic behavior at a single-lane roundabout. Vehicles can enter the interior lane or exit from it via intersecting lane, the boundary conditions are stochastic. The traffic is controlled by a self-organized scheme. It has turned out that depending on the rules of insertion to the roundabout, five distinct traffic phases can appear, namely, free flow, congestion, maximum current, jammed and gridlock. The transition between the free flow and the gridlock is forbidden. The density profiles are used to study the traffic pattern at the interior lane of the roundabout. In order to quantify the interactions between vehicles in the interior lane of the roundabout, the velocity correlation coefficient (VCC) is also studied. Besides, the spatiotemporal diagrams corresponding to the entry/exit lanes are derived numerically. Furthermore, we have investigated the effect of displaying signal (, as the decreases, the maximum current increases at the expense of the free flow and the jamming phase. Finally, we have investigated the effect of the braking probability on the interior lane of the roundabout. We have found that the increase of raises the spontaneous jam formation on the ring. Thus, enlarges the maximum current and the jamming phase while the free flow phase decreases. [ABSTRACT FROM AUTHOR]

Presents the table of contents for this issue of the publication. [ABSTRACT FROM AUTHOR]

This study proposes a cellular automaton model incorporating the platoon size of connected automated vehicles (CAVs) to examine their impact on mixed traffic flow. First, vehicles are classified into three modes, human-driven vehicles (HDVs), adaptive cruise control (ACC), and cooperative adaptive cruise control (CACC), by considering the characteristics of the car-following behavior. Second, the CACC is further subdivided into interplatoon and intraplatoon car-following modes due to the limitations of the platoon size of CAVs. Then, cellular automaton rules are developed for each of these four modes. Finally, numerical simulation experiments are conducted to analyze the influence of the penetration rate and platoon size of CAVs on mixed traffic flow. The results demonstrate that (1) the simulation results closely align with the theoretically derived outcomes, with an error rate of only 0.46% at a penetration rate of 100%; (2) when the penetration rate of CAVs reaches 100%, increasing the platoon size further enhances the traffic capacity; and (3) the optimal platoon size is determined to be seven CAVs under moderate traffic density., Author(s): Yangsheng Jiang [1,2,3]; Zhiyuan Yi [1,2]; Guosheng Xiao [1,2]; Hongwu Li [1,2,3]; Zhihong Yao (corresponding author) [1,2,3] 1. Introduction Autonomous vehicles are increasingly entering our range of vision as [...]