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This paper aims to consider a single server queue with system disasters and impatience behavior are evident in our daily life. For this purpose, authors require to know the general behavior of these systems. Transient analysis shows for us how the system will operate up to some time instant t.

In this paper, authors consider a single server queue with system disaster and impatient behavior of customers in a multi-phase random environment, in which the system transits to a repair state after each system disaster. When the system is in a failure phase or going through a repair phase, the new arrivals would be impatient. In case the system is not repaired before the customer’s time expires, the customer would leave the queue and never return. Moreover, after repair, the system becomes ready for service in an operative phase with probability $q_{i} \ge 0.$. Using generating functions along with continued fractions and some properties of the confluent hypergeometric function, authors obtained on their own results.

Explicit expressions have been obtained for the time-dependent probabilities of the underlying queuing model. Also, time-dependent mean and variance of customers in the system are deduced.

The system authors are dealing with is somewhat complicated, there are some performance measures that cannot be achieved, but some of them have been obtained, such as the expectation and variance of the number of customers in the system.

Based on the obtained results, some numerical examples are some numerical examples are presented to illustrate the effect of various parameters on the behavior of the proposed system.

Authors’ studied transient analysis of a single server queue with system disaster and impatient customer system is suitable for behavior interpretation of many systems in our lives, such as telecommunication networks, inventory systems and impatient telephone switchboard customers, manufacturing system and service system.

To the best of the author’s/authors’ knowledge and according to the literature survey, in a multi-phase random environment, no previous published article is presented for transient analysis of a single server queue with system disaster and impatient customer behavior in a random environment.

Small unmanned aircraft systems (sUAS) are becoming increasingly popular among hobbyists, and with this popularity there comes the risk of runway incursion between a commercial aircraft and sUAS around airports. To keep airports safe and secure, the purpose of this paper is to propose a module, called the Airport Secure Perimeter Control System, that can be attached to every hobbyist’s sUAS for the purpose of notification and prevention.

Upon startup, the module connects to a database containing the central coordinates of every airport in the USA. A five-mile critical radius plus an additional one-mile buffer region is established around each point. The buffer region is created in order to inform the user that he/she is approaching a safe airspace and needs to take corrective action. Once the five-mile zone has been breached, autopilot software takes over the manual controls, and the sUAS is landed in a controlled manner, while the user still has lateral control of the vehicle in order to avoid any potential hazards below it. Then, both operator and airport receive messages about the event.

To demonstrate the proposed design, a prototype was developed that successfully implemented this system, and was formally tested within a controlled environment.

This solution would drastically reduce the security threat of sUAS breaching the critical regions surrounding airports, and its implementation is relatively simple.

The main purpose of this paper is to gain a better understanding of the transient aerodynamic characteristics of moving windshield wipers. In addition, this paper also strives to illustrate and clarify how the wiper motion impacts the airflow structure; the aerodynamic interaction of two wipers is also discussed.

A standard vehicle model proposed by the Motor Industry Research Association and a pair of simplified bone wipers are introduced, and a dynamic mesh technique and user-defined functions are used to achieve the wiper motion. Finite volume methods and large eddy simulation (LES) are used to simulate the transient airflow field. The simulation results are validated through the wind tunnel test.

The results obtained from the study are presented graphically, and pressure, velocity distributions, airflow structures, aerodynamic drag and lift force are shown. Significant influences of wiper motion on airflow structures are achieved. The maximum value of aerodynamic lift and drag force exists when wipers are rotating and there is a certain change rule. The aerodynamic lift and drag force when wipers are rotating downward is greater than when wipers are rotating upward, and the force when rotating upward is greater than that when steady. The aerodynamic lift and drag forces of the driver-side wiper is greater than those of the passenger-side wiper.

The LES method in combination with dynamic mesh technique to study the transient aerodynamic characteristics of windshield wipers is relatively new.

This study aims to provide a time- and price-sensitive market strategy for merchants to handle the markdown price strategy. The market demand for perishable products is usually price – and quality (freshness) – sensitive. The proper handling of markdown-price strategies can help merchants enhance competitiveness and maximize operational performance.

A markdown strategy consisting of price and markdown time was developed to explore the properties of market strategies based on the dynamic quality evaluation. The strategy considers multiple price discounts and multiple markdown times. The optimal price decisions in each stage and the optimal markdown times were derived during the selling season.

The results showed the following. A retailer always raises the initial price if it wants to adopt multiple price-markdown strategies. A high initial price may lead to a high inventory at the early stage and bring the next price reduction in advance. Large price discounts can be used to reduce the inventory later. The higher the previous price, the shorter the interval between the next price reduction. The markdown strategies showed that the regular discount as a new business model is not the best pricing model for perishable products. A time- and price-sensitive strategy, however, can increase operational performance and provide new insights for perishable products.

The results showed the following. A retailer always raises the initial price if it wants to adopt multiple price-markdown strategies. A high initial price may lead to a high inventory at the early stage and bring the next price reduction in advance. Large price discounts can be used to reduce the inventory later. The higher the previous price, the shorter the interval between the next price reduction. The markdown strategies showed that the regular discount as a new business model is not the best pricing model for perishable products. A time- and price-sensitive strategy, however, can increase operational performance and provide new insights for perishable products.

The purpose of this paper is to develop a simple chaotic circuit. The circuit can be fabricated by less discrete electronic components, within which complex dynamical behaviors can be generated.

A second-order non-autonomous inductor-free chaotic circuit is presented, which is obtained by introducing a sinusoidal voltage stimulus into the classical Wien-bridge oscillator. The proposed circuit only has two dynamic elements, and its nonlinearity is realized by the saturation characteristic of the operational amplifier in the classical Wien-bridge oscillator. After that, its dynamical behaviors are revealed by means of bifurcation diagram, Lyapunov exponent and phase portrait and further confirmed using the 0-1 test method. Moreover, an analog circuit using less discrete electronic components is implemented, and its experimental results are measured to verify the numerical simulations.

The equilibrium point located in a line segment varies with time evolution, which leads to the occurrence of periodic, quasi-periodic and chaotic behaviors in the proposed circuit.

Unlike the previously published works, the significant values of the proposed circuit with simple topology are inductor-free realization and without extra nonlinearity, which make the circuit can be used as a paradigm for academic teaching and experimental illustraction for chaos.

This paper aims to answer the question of how, why and when abusive supervision affects employee creativity. Drawing on the conservation of resources theory, this paper examines the direct and indirect (via psychological distress) effects of abusive supervision on employee creativity. It further investigates the boundary conditions imposed by employees’ perceived distributive and procedural justice in the relationships between abusive supervision, psychological distress and employee creativity.

The study uses multi-sourced and time-lagged data collected in three waves from a survey of employees-supervisor dyads working in the Chinese manufacturing sector. In the first wave, the authors received data from 347 employees on perceived abusive supervision and perceived distributive and procedural justice. In the second wave, 320 employees shared their perceptions of psychological distress at work. In the third wave, the authors received ratings for employee creativity from the direct supervisors of 300 employees. The data were analyzed using bootstrapped moderated mediation procedures.

The findings revealed a significant negative influence of abusive supervision on employee creativity both directly and indirectly in the presence of perceived psychological distress. However, distributive and procedural justice was found to mitigate the negative impact of abusive supervision on employee creativity.

Abusive supervision has adverse consequences for employees’ creativity because it affects their psychological health. HR and top management should prioritize addressing abusive supervision first and foremost to boost employee creativity in the workplace. Managers should give employees opportunities for participation and foster a climate of fairness in the organization to mitigate the harmful consequences of abusive supervision.

To the best of the authors’ knowledge, this is the first empirical study that examines the psychological distress-based mechanism in the relationship between abusive supervision and creativity while considering the interactive effects of distributive and procedural justice. It addresses an important research gap in the literature by proposing that organizational perceived distributive and procedural justice can mitigate the detrimental effects of abusive supervision.

The purpose of this study is to integrate research on competitive and cooperative repertoires and to simultaneously assess the direct, indirect and curvilinear effects of competitive and cooperative action repertoires in relation to firm performance.

The analyses are conducted using a longitudinal dual-industry sample of publicly traded firms, including over 6,500 competitive actions and 750 cooperative actions. The authors use fixed effects (FE) regression models to test the diminishing returns of action volume on firm performance as well as the moderating effects of action diversity.

The results suggest that increasing competitive and cooperative actions yields diminishing returns in relation to firm performance. Furthermore, in the context of competitive action repertoire diversity, increased diversity magnifies the diminishing returns of competitive action volume on firm performance.

The study provides a firm-level conceptualization of overall competitive and cooperative repertoires to extend the literature on competition and cooperation beyond dyadic interactions or structural determinants of competitive and cooperative actions.

This review aims to give a critical view of the wheel/rail high frequency vibration-induced vibration fatigue in railway bogie.

Vibration fatigue of railway bogie arising from the wheel/rail high frequency vibration has become the main concern of railway operators. Previous reviews usually focused on the formation mechanism of wheel/rail high frequency vibration. This paper thus gives a critical review of the vibration fatigue of railway bogie owing to the short-pitch irregularities-induced high frequency vibration, including a brief introduction of short-pitch irregularities, associated high frequency vibration in railway bogie, typical vibration fatigue failure cases of railway bogie and methodologies used for the assessment of vibration fatigue and research gaps.

The results showed that the resulting excitation frequencies of short-pitch irregularity vary substantially due to different track types and formation mechanisms. The axle box-mounted components are much more vulnerable to vibration fatigue compared with other components. The wheel polygonal wear and rail corrugation-induced high frequency vibration is the main driving force of fatigue failure, and the fatigue crack usually initiates from the defect of the weld seam. Vibration spectrum for attachments of railway bogie defined in the standard underestimates the vibration level arising from the short-pitch irregularities. The current investigations on vibration fatigue mainly focus on the methods to improve the accuracy of fatigue damage assessment, and a systematical design method for vibration fatigue remains a huge gap to improve the survival probability when the rail vehicle is subjected to vibration fatigue.

The research can facilitate the development of a new methodology to improve the fatigue life of railway vehicles when subjected to wheel/rail high frequency vibration.

Describes a new catalytic gas sensor which claims high stability and low‐consumed power by using extra fine wires of precious metals and the addition of a support stabilizer and pore‐making agents. Outlines the experiment methods and materials used, the principles of detection and the performance of the catalytic elements. Concludes that with the addition of a support stabilizer which makes the specific surface of the support decrease slowly during use, and a pore‐making agent which can eliminate the effect of the internal diffusion on the sensor, the novel catalytic sensor can be widely applied to the detection of damp gas in coal mines and various combustible gases on the earth’s surfaces.

This paper aims to comprehensively clarify the research status of thermal transport of supercritical aviation kerosene, with particular interests in the effect of cracking on heat transfer.

A brief review of current research on supercritical aviation kerosene is presented in views of the surrogate model of hydrocarbon fuels, chemical cracking mechanism of hydrocarbon fuels, thermo-physical properties of hydrocarbon fuels, turbulence models, flow characteristics and thermal performances, which indicates that more efforts need to be directed into these topics. Therefore, supercritical thermal transport of n-decane is then computationally investigated in the condition of thermal pyrolysis, while the ASPEN HYSYS gives the properties of n-decane and pyrolysis products. In addition, the one-step chemical cracking mechanism and SST k-ω turbulence model are applied with relatively high precision.

The existing surrogate models of aviation kerosene are limited to a specific scope of application and their thermo-physical properties deviate from the experimental data. The turbulence models used to implement numerical simulation should be studied to further improve the prediction accuracy. The thermal-induced acceleration is driven by the drastic density change, which is caused by the production of small molecules. The wall temperature of the combustion chamber can be effectively reduced by this behavior, i.e. the phenomenon of heat transfer deterioration can be attenuated or suppressed by thermal pyrolysis.

The issues in numerical studies of supercritical aviation kerosene are clearly revealed, and the conjugation mechanism between thermal pyrolysis and convective heat transfer is initially presented.