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A vacuum circuit breaker (VCB) operates with a mechanical mechanism that ensures rapid arc quenching, reliable protection, and current interruption in high-voltage electrical systems. Over the past few decades, numerous engineering teams and researchers have explored this issue. However, despite the importance of precise timing in VCBs, no analytical method currently exists to investigate the dynamic response of their mechanical mechanisms. Existing approaches rely heavily on numerical simulations or experimental testing, which are often time-consuming, computationally expensive, and impractical for extensive parametric studies. In this study, the time response of a VCB case study is investigated through multi-body dynamic analysis for both opening and closing conditions. Additionally, the optimal spring characteristics of the mechanism are explored, and a SolidWorks model of a manufactured VCB was created as a case study to achieve this objective. The angular relationships of the mechanism’s links were analyzed for both opening and closing actions. From these relationships, angular velocities were derived and incorporated into work-energy equations and boundary conditions from the SolidWorks model to determine the mechanism’s time response. The results indicate an opening time of 39.9 ms and a closing time of 60.5 ms.

Among all circuit breaker faults, mechanical failures account for a considerable proportion, and online monitoring of their mechanical characteristics is of great practical significance. The opening and closing time is a very important feature of the mechanical characteristics of the circuit breaker. Online monitoring of the opening and closing time of the circuit breaker has always been the focus and difficulty of the intelligent technology of switchgear. In this paper, for a 10 kV spring energy storage vacuum circuit breaker, transient voltage and current signals are innovatively used to calibrate the opening time, breaking time, and closing time, and an online monitoring method for the opening and closing time of a vacuum circuit breaker based on transient electrical signals is proposed. An online monitoring platform was built and a multi-group closing test was carried out to simulate the power plant environment. The opening and closing time samples of a spring energy storage vacuum circuit breaker were measured and compared with the measurement results of the mechanical properties tester. The comparison results show that this method has good stability, and the calculation error is controlled within 1% after self-calibration, which provides a new idea for the online monitoring research of the mechanical characteristics of spring energy storage vacuum circuit breakers.

Energisation of large power transformers may cause significant voltage dips, of which the severity largely depends on a number of parameters, including circuit breaker closing time, transformer core residual flux and core saturation characteristic, and network conditions. Since most of the parameters are of stochastic nature, Monte Carlo simulation was conducted in this study to stochastically assess the voltage dips caused by transformer energisation in a 400 kV grid, using a network model developed and validated against field measurements. A dip frequency pattern was identified over 1000 stochastic runs and it was found to be sensitive to residual flux distribution but insensitive to closing offset time distribution. The probability of reaching the worst case dip magnitude (estimated under the commonly agreed worst energisation condition) was found to be lower than 0.5%; about 80% of the dips are likely to be with magnitudes lower than 0.6 pu of the worst case. Nevertheless, there are dips with magnitudes exceeding the worst case dip magnitude, indicating the inadequacy of deterministic assessment approach by using the commonly agreed worst energisation condition.

The results of studies of a solid-state closing switch for a high-current pulse switching are presented. The experiments were carried out on a laboratory facility with a capacitive energy storage run down a discharge circuit with electrical-explosive opening switch (EEOS) by a current pulse with an amplitude ~450 kA. The discharge circuit consists of two sections separated by a branch with a solid-state closing switch. A metal foil of the EEOS can be located in an interelectrode gap of the closing switch. The operation of the EEOS leads to a breakdown of the insulation of the closing switch, as a result of which an effective shunting of the section of the discharge circuit containing the EEOS occurs. The developed combined solid-state closing switch in the future is capable of providing multi-channel switching of a high-current pulse to the load synchronously with the EEOS operation.

Cross-pollination in cultivated rice (Oryza sativa L.) is rarely reported to exceed 2%. This low cross-pollination frequency (CPF) is conducive to successfully maintaining the purity of rice landraces for many generations. We were therefore surprised to notice a dramatic loss of genetic purity in some of the pure line landraces in many farmers’ fields. Having ruled out the possibility of mixing of seeds from different varieties, we surmised this rapid loss of genetic purity to be due to a somewhat higher degree of cross-pollination, and conducted a carefully designed experiment with suitably chosen pairs of landraces. We report here an unusually high (>81%) CPF seen in a pair of landraces whose flower opening times (FOTs) were coincident. Our control experiment on a pair of landraces with non-overlapping FOTs failed to detect any cross-pollination. This preliminary report suggests that the crucial importance of FOT diversity in landraces in determining CPF has not been recognized in designs of previous reports of crossing experiments, resulting in a severe underestimation of CPF in cultivated rice under natural conditions.

This paper reviews and compares electrostatically actuated MEMS (micro-electro-mechanical system) arrays for light modulation and light steering in which transmission through the substrate is required. A comprehensive comparison of the technical achievements of micromirror arrays and microshutter arrays is provided. The main focus of this paper is MEMS micromirror arrays for smart glass in building windows and façades. This technology utilizes millions of miniaturized and actuatable micromirrors on transparent substrates, enabling use with transmissive substrates such as smart windows for personalized daylight steering, energy saving, and heat management in buildings. For the first time, subfield-addressable MEMS micromirror arrays with an area of nearly 1 m2 are presented. The recent advancements in MEMS smart glass technology for daylight steering are discussed, focusing on aspects like the switching speed, scalability, transmission, lifetime study, and reliability of micromirror arrays. Finally, simulations demonstrating the potential yearly energy savings for investments in MEMS smart glazing are presented, including a comparison to traditional automated external blind systems in a model office room with definite user interactions throughout the year. Additionally, this platform technology with planarized MEMS elements can be used for laser safety goggles to shield pilots, tram, and bus drivers as well as security personal from laser threats, and is also presented in this paper.

The water transfer project has alleviated the shortage of water resources, but frequent scheduling of water distribution hubs can harm the water transmission buildings. This article is based on the RNG k-ε turbulence model to construct a three-dimensional mathematical model of the water flow passing through the gate of the North-Line of the Huangchigou water distribution hub of the water diversion from the Han to the Wei River. Combined with the physical model experiment,  the influence of the unsteady flow process of the North-line of the Huangchigou water distribution hub on the hydraulic response in its water distribution tank and tunnel is investigated. The research results indicate that, when the North-line gate closes faster, the earlier the overflow occurs in the side-channel spillway, increasing in abandoned water volume. In addition, excessively rapid gate adjustment can result in a sharp increase in pressure in front of the North-line gate. It will also increase the cavity area caused by the detachment of the bottom edge of the gate, forming a strong vortex behind the gate. From the perspective of safe operation of the gate, the closing time of the North-line gate should not be less than 100s. The research results can provide reference for the design, safe operation, and emergency control of water transmission and distribution hub projects.

With the increasing popularity of long-distance water supply projects and the development of materials technology, the variation of water hammer characteristics in the viscoelastic pipeline has become the focus of researchers. To find out the mechanism of water hammer in the viscoelastic pipe of both elastic and viscous properties, an experiment was set up to study the direct water hammer generated by rapid closure of the downstream valve in the polymethyl methacrylate (PMMA) pipe, with six flow velocities in nearly 70 tests. The experimental results showed that the maximum water hammer pressure generated in the viscoelastic pipe in all flow velocities was (20% at most) greater than the traditional value of Joukowsky's formula. A faster closing time of the valve caused a higher water hammer pressure. The difference in water hammer pressure generated between the fastest and the slowest closing time of the valve was 14–17% at each flow velocity. Based on the relationship between the stress and strain of the pipe wall in the viscoelastic pipe, the reason that the water hammer characteristic in the viscoelastic pipeline was different from the traditional value was explained. The study provides a reference for the mechanism of transient flow in viscoelastic pipelines.

•Front line employees issue cues to signal closing time is approaching.•Cues issued by front line employee lead to intrusion pressure, with mixed support found for productive cues.•Intrusion pressure from front line employees triggers territorial responses from customers.•Territorial responses include yielding, retaliation, abandonment, temporary abandonment, and negative word of mouth.•Identification with the store can heighten or dampen the effects of customers’ perceptions of encroachment. Retailers can benefit from an increased understanding of how human territoriality affects their relationships with customers. In the context of closing time, we show that issuance of boundary markers, or closing time cues, before the closing time boundary can result in perceptions of territory intrusion and territorial responses from customers. In study 1, we identify six types of cues used by employees to signal to customers the closing time boundary is approaching: productive, personal, audio–visual, withdrawal, hostility, and blocking cues. Three additional studies show these cues affect customers’ perceptions of intrusion pressure and their subsequent territorial responses, including: retaliation, abandonment and accession (studies 2–4) and negative word of mouth and temporary abandonment (study 4). Additionally, identification with the store can heighten or dampen the effects of customers’ perceptions of encroachment on their territorial responses (studies 3 and 4), depending on the retail context.

To address the issues of cumulative plastic deformation and low-cycle fatigue cracking in ultra-high voltage (UHV) disc spring hydraulic circuit breakers under long-term cyclic high-pressure loads, which lead to internal structural changes and affect closing time stability and phase-controlled closing accuracy, this paper proposes a closing time prediction model considering the low-cycle fatigue of the operating mechanism. First, a Simulink-based simulation model of the 550 kV disc spring hydraulic operating mechanism transmission system was developed to analyze the influence of structural parameter variations on closing time under no-load conditions. Then, an objective function for judging action time stability was constructed, and the stability and influence weights of each structural parameter were calculated under different mechanical dispersion requirements using a combination of adaptive surrogate models and directional importance sampling. Results show that critical parameters such as working cylinder inner diameter, working cylinder stroke, main valve stroke, and working cylinder rod diameter significantly affect closing time, contributing approximately 25%, 20%, 15%, and 10%, respectively. Finally, a dynamic-weighted closing time prediction model was designed based on different phase-controlled accuracy requirements. Compared with no-load closing tests, under mechanical dispersion conditions of ±1 ms, ±1.5 ms, and ±2 ms, the optimized model reduced maximum deviations by 12.8%, 20.4%, and 23.3%, and narrowed fluctuation ranges by 37%, 38.3%, and 38.6%, respectively, significantly improving prediction accuracy. This work is supported by the Science and Technology Project of China Southern Power Grid (No.CGYKJXM20220346).