Parameters’ changing influence with different lateral stiffnesses on nonlinear analysis of hunting behavior of a bogie

Conventionally a railway vehicle has stable motion in low speeds, when it reaches to high speeds stability changes to unstable form. The main purpose of this article is to show the authors' view of analytical investigation of bifurcation, nonlinear lateral stability and hunting behavior of rail vehicles in a tangent track. The paper includes nonlinear primary yaw dampers, and flange contact and also bogie existence. This study contains Bogoliubov method for the analysis. Linear and nonlinear critical speeds are obtained, and changing parameters' effect in differing the speeds with altered lateral stiffness in primary suspension system has been studied. General works about hunting phenomenon show that nonlinear critical speed is less than linear one

Parameters’ changing influence with different lateral stiffnesses on nonlinear analysis of hunting behavior of a bogie

Conventionally a railway vehicle has stable motion in low speeds, when it reaches to high speeds stability changes to unstable form. The main purpose of this article is to show the authors' view of analytical investigation of bifurcation, nonlinear lateral stability and hunting behavior of rail vehicles in a tangent track. The paper includes nonlinear primary yaw dampers, and flange contact and also bogie existence. This study contains Bogoliubov method for the analysis. Linear and nonlinear critical speeds are obtained, and changing parameters' effect in differing the speeds with altered lateral stiffness in primary suspension system has been studied. General works about hunting phenomenon show that nonlinear critical speed is less than linear one

A fruit pick-up mechanism for reducing dust generation in almond pick-up machines

This doctoral research addresses a critical environmental challenge in California's almond orchards: the pervasive dust pollution stemming from traditional almond harvesting methods. As the leading producer of almonds, supplying over 80 percent of the global demand, California has long been confronted with the adverse effects of these practices on air quality and health, notably the substantial emissions of particulate matter (PM), particularly PM2.5 and PM10.At the core of my study was the conception, design, and iterative development of an innovative low-dust sweeping system aimed at drastically reducing dust emissions during almond harvesting. This journey involved the creation and successive refinement of ten distinct versions of the machine, each iteration addressing limitations and inefficiencies identified in its predecessor. This meticulous process of design and modification was pivotal in evolving the system to its final form, incorporating a sophisticated feedback control mechanism that intelligently adjusts the sweeper brushes’ height and speed in synchrony with the harvester's movement. This innovation significantly refined the interaction between the brushes and the ground, reducing unnecessary sweeping and, as a result, mitigating dust generation. Comparative field tests with conventional harvesting equipment from renowned brands like Flory, Weiss McNair, and Jack Rabbit in Fresno County orchards established that our final low-dust model, encapsulating the refinements from previous versions, notably outperformed its predecessors in minimizing PM emissions. Furthermore, this research made a significant stride in predicting PM2.5 emissions, a previously unaddressed challenge in California's almond industry. The absence of a reliable emission factor for PM2.5 has been a significant barrier to regulatory compliance and emissions inventory. The predictive model developed as part of this research is a substantial contribution toward understanding and managing the environmental impact of almond harvesting operations. In conclusion, the final version of the low-dust almond harvesting system developed through this research not only meets but surpasses California's air quality standards. It offers an effective, environmentally responsible solution for the almond industry, embodying the essence of sustainable innovation and marking a significant step forward in harmonizing agricultural efficiency with environmental stewardship

Design of an Integrated Controller for a Sweeping Mechanism of a Low-Dust Almond Pickup Machine

California is the world’s biggest producer and exporter of almonds. Currently, the sweeping of almonds during the harvest creates a significant amount of dust, causing air pollution in the neighboring urban areas. A low-dust sweeping system was designed to reduce the dust during the sweeping of almonds in the orchard. The system includes a feedback control system to control the sweeper brushes’ height and their angular velocity by adjusting the forward velocity of the harvester and the brushes’ rotational speeds to avoid any extra overlapping sweeping, which increases dust generation. The governing kinematic equations for sweepers’ angular velocity and vehicle forward speed were derived. The feedback controllers for synchronizing these speeds were designed to optimize brush/dust contact to minimize dust generation. The sweepers’ height controller was also designed to stabilize the gap between the brushes and the orchard floor and track the road trajectory. Controllers were simulated and tuned for a fast response for agricultural applications with less than a second response delay. Results showed that the designed system has acceptable performance and generates low amounts of dust within the acceptable range of California ambient air quality standards

Design of an Integrated Controller for a Sweeping Mechanism of a Low-Dust Almond Pickup Machine

California is the world's biggest producer and exporter of almonds. Currently, the sweeping of almonds during the harvest creates a significant amount of dust, causing air pollution in the neighboring urban areas. A low-dust sweeping system was designed to reduce the dust during the sweeping of almonds in the orchard. The system includes a feedback control system to control the sweeper brushes' height and their angular velocity by adjusting the forward velocity of the harvester and the brushes' rotational speeds to avoid any extra overlapping sweeping, which increases dust generation. The governing kinematic equations for sweepers' angular velocity and vehicle forward speed were derived. The feedback controllers for synchronizing these speeds were designed to optimize brush/dust contact to minimize dust generation. The sweepers' height controller was also designed to stabilize the gap between the brushes and the orchard floor and track the road trajectory. Controllers were simulated and tuned for a fast response for agricultural applications with less than a second response delay. Results showed that the designed system has acceptable performance and generates low amounts of dust within the acceptable range of California ambient air quality standards

Effects of the change in auto coupler parameters on in-train longitudinal forces during brake application

For long freight trains, the pneumatic brake systems are still used. In these situations, the cars at the end of the train brake a few seconds later than those wagons at the front. This variable braking action along the train may cause large longitudinal forces and impacts. Beside brake system parameters, auto coupler characteristics parameters have high importance in longitudinal train dynamics. Therefore, simulations of effects of the change in auto coupler parameters on in-train longitudinal forces during brake application are very important both for safety and economic reasons since longer freight trains imply higher transport costs reductions. In the present paper, effects of the change in coupling parameters such as stiffness, damping, and clearance and train speed, on the longitudinal train dynamics were investigated during brake application. The results indicate dramatic changes in the way that cars interact dynamically with each other and the magnitudes of the in-train longitudinal compression and tensile forces along the train. The freight train considered is in current use by Iranian Railways