Motorized Wireless-Charging Pad that Uses Magnetic Field Detection

This publication describes a motorized wireless power transfer (WPT) system (e.g., motorized Qi charger) that utilizes tunnel magnetoresistance (TMR) to automatically laterally and vertically align the transmitter (Tx) of the WPT system to the receiver (Rx) of a user equipment (UE), such as a smartphone, earphones, a smartwatch, and so forth. The WPT system has TMR sensors that utilize magnetic tunnel junction (MTJ) elements that exhibit low magnetic hysteresis and high magnetoresistance sensitivity to a change in the magnetic field. An array of TMR sensors can be used to reliably detect the magnetic field distribution and can detect the lateral, vertical alignment, and/or misalignment between the Tx of the WPT system and the Rx of the UE. The exact number and spatial arrangements of the TMR sensors may differ depending on the shape and size of the charging pad of the WPT system. The WPT system may have one, two, three, and so forth, transmitters sitting on top of one, two, three, and so forth, motorized arms that enable the WPT system to automatically laterally and/or vertically align to and charge one, two, three, and so forth, UE at the same time. The described WPT system can support different-size UE, can wirelessly charge multiple UE at the same time, increases the coupling coefficient, increases the transferred-power efficiency, decreases power loss, decreases charging time, may mitigate damages to the UE and the WPT system caused by thermal energy, enhances user experience, and enables a user to use electric energy more efficiently

Motorized coil wireless charger with coil alignment mechanism

The disclosure describes techniques to improve power transfer efficiency of a wireless charger through a coil alignment mechanism. A transmitter coil of a wireless charger is configured with step motors and gears, and can travel in a radial motion and towards or away from a central point to align with the receiver coil of a device across the charging surface. Further, the transmitter coil can also be moved in a direction perpendicular with respect to the charging surface which can help optimize the distance from the receiver coil. Charging efficiency and stability between the transmitter and receiver coils are measured using signal strength of packets

A stochastic game framework for patrolling a border

In this paper we consider a stochastic game for modelling the interactions between smugglers and a patroller along a border. The problem we examine involves a group of cooperating smugglers making regular attempts to bring small amounts of illicit goods across a border. A single patroller has the goal of preventing the smugglers from doing so, but must pay a cost to travel from one location to another. We model the problem as a two-player stochastic game and look to find the Nash equilibrium to gain insight to real world problems. Our framework extends the literature by assuming that the smugglers choose a continuous quantity of contraband, complicating the analysis of the game. We discuss a number of properties of Nash equilibria, including the aggregation of smugglers, the discount factors of the players, and the equivalence to a zero-sum game. Additionally, we present algorithms to find Nash equilibria that are more computationally efficient than existing methods. We also consider certain assumptions on the parameters of the model that give interesting equilibrium strategies for the players

Containment of socially optimal policies in multiple-facility Markovian queueing systems

We consider a Markovian queueing system with N heterogeneous service facilities, each of which has multiple servers available, linear holding costs, a fixed value of service and a first-come-first-serve queue discipline. Customers arriving in the system can be either rejected or sent to one of the N facilities. Two different types of control policies are considered, which we refer to as ‘selfishly optimal’ and ‘socially optimal’. We prove the equivalence of two different Markov Decision Process formulations, and then show that classical M/M/1 queue results from the early literature on behavioural queueing theory can be generalized to multiple dimensions in an elegant way. In particular, the state space of the continuous-time Markov process induced by a socially optimal policy is contained within that of the selfishly optimal policy. We also show that this result holds when customers are divided into an arbitrary number of heterogeneous classes, provided that the service rates remain non-discriminatory

Atlantis: and other lost cities

"Fact or Fiction?" looks at different interpretations of these tales and what may be the reality behind the mythology that has inspired artists and writers throughout the centuries

A conservative index heuristic for routing problems with multiple heterogeneous service facilities

We consider a queueing system with N heterogeneous service facilities, in which admission and routing decisions are made when customers arrive and the objective is to maximize long-run average net rewards. For this type of problem, it is well-known that structural properties of optimal policies are difficult to prove in general and dynamic programming methods are computationally infeasible unless N is small. In the absence of an optimal policy to refer to, the Whittle index heuristic (originating from the literature on multi-armed bandit problems) is one approach which might be used for decision-making. After establishing the required indexability property, we show that the Whittle heuristic possesses certain structural properties which do not extend to optimal policies, except in some special cases. We also present results from numerical experiments which demonstrate that, in addition to being consistently strong over all parameter sets, the Whittle heuristic tends to be more robust than other heuristics with respect to the number of service facilities and the amount of heterogeneity between the facilities

Power Transmission for a Passive Rehabilitation Device

ME450 Capstone Design and Manufacturing Experience: Winter 2015We were commissioned to design a high-efficiency passive mechanical-power transmission for future implementation into a human body-powered device proposed for self-assisted physical rehabilitation. Further, we were tasked with developing a model of the transmission, with a focus on losses, and a physical prototype that will be used to validate that model. Our system will be testing hydraulic and pneumatic pistons against a benchmark of Bowden cables, focusing on efficiency as the comparative factor. In order to validate our design choices, models of both the pneumatic and hydraulic actuators were created. The pneumatic model had to take into account the compressibility of the working fluid as well as the thermodynamics of the process, increasing the complexity of analysis. Our hydraulic model is based off of Durphy’s model of hydraulic cylinders, allowing us to visualize how changing a single variable affects efficiency.http://deepblue.lib.umich.edu/bitstream/2027.42/111313/1/16_Report.pd