Deformation of the silo wall due to the single ball impact is modeled in ANSYS. The material in silo, as a Winkler bed, is replaced by spring-damper elements and the spring stiffness and damper coefficients are evaluated of the granular material and wall properties. The granular material deformation under the specified force is measured to evaluate the granular stiffness to be used for determin...

MIT is developing an Earth-based hopper prototype for autonomous planetary exploration. This paper describes the initial development of the hopper prototype and its application as a testbed for lunar hopper technologies. The prototype hopper consists of a gravity-canceling system, composed of battery-powered electric ducted fans, and an integrated lunar hopper system, which operates using cold ...

The Murφ-based Hopper tool is a general purpose explicit model checker. Hopper leverages Murφ’s class structure to implement new algorithms. Hopper differs from Murφ in that it includes in its distribution published parallel and disk based algorithms, as well as several new algorithms. For example, Hopper includes parallel dynamic partitioning, cooperative parallel search for LTL violations and...

This study investigated generalization decrement during an extinction resistance-to-change test for pigeon key pecking using a two-component multiple schedule with equal variable-interval 3-min schedules and different reinforcer amounts (one component presented 2-s access to reinforcement and the other 8s). After establishing baseline responding, subjects were assigned to one of the two extinct...

The discharge of granular material from a hopper subject to vertical sinusoidal oscillations was investigated using experiments and discrete element computer simulations. With the hopper exit closed, side-wall convection cells are observed, oriented such that particles move up along the inclined walls of the hopper and down at the center line. The convection cells are a result of the granular b...

Jenike’s radial solution, widely used in the design of materials-handling equipment, is a similarity solution of steady-state continuum equations for the flow under gravity of granular material through an infinite, right-circular cone. In this paper we study how the geometry of the hopper influences this solution. Using perturbation theory, we compute a first-order correction to the (steady-sta...

In this paper, we study the global dynamics of a simple passive mechanical model for hopping. The hopper is a two-mass, single-spring system constrained to move in the vertical direction (under gravity) above a rigid ground. The hopper model and its basic dynamics including the existence of incessant hopping motions have been reported elsewhere. Here, we extend the study to investigate the glob...

Two-dimensional (2D) hopper flow of disks has been extensively studied. Here, we investigate hopper flow of ellipses with aspect ratio α = 2, and we contrast that behavior to the flow of disks. We use a quasi-2D hopper containing photoelastic particles to obtain stress/force information. We simultaneously measure the particle motion and stress. We determine several properties, including dischar...

An experiment was conducted in Field Laboratory, Department of Entomology at Bangladesh Agricultural University, Mymensingh, during 2013 to manage the mango hopper, Idioscopus clypealis L, using three chemical insecticides, Imidacloprid (0.3%), Endosulfan (0.5%), and Cypermethrin (0.4%), and natural Neem oil (3%) with three replications of each. All the treatments were significantly effective i...