Abstract: A system for monitoring shopping carts uses cameras to generate images of the carts moving in a store. In some implementations, cameras may additionally or alternatively be mounted to the shopping carts and configured to image cart contents. The system may use the collected image data, and/or other types of sensor data (such as the store location at which an item was added to the basket), to classify items detected in the shopping carts. For example, a trained machine learning model may classify item in a cart as “non-merchandise,” “high theft risk merchandise,” “electronics merchandise,” etc. When a shopping cart approaches a store exit without any indication of an associated payment transaction, the system may use the associated item classification data, optionally in combination with other data such as cart path data, to determine whether to execute an anti-theft action, such as locking a cart wheel or activating a store alarm.

Abstract: A system for monitoring and controlling shopping cart usage comprises a wheel assembly that attaches to a shopping cart. In some embodiments the wheel assembly includes a wheel, a brake that can be activated to inhibit rotation of the wheel, a controller that controls the brake, a VLF receiver, and an RF transceiver. The RF transceiver may, for example, operate in a 2.4 GHz frequency band. In some implementations, the RF transceiver may be used to detect entry of the shopping cart into a checkout area of the store, and the VLF receiver may be used to detect that the shopping cart is exiting the store. The controller may activate the brake if the shopping cart attempts to exit the store without first passing through a checkout area.

Abstract: A compound semiconductor whose elements are differently volatile (e.g. GaAs, where As is more volatile than Ga) can be surface-passivated (a Ga layer overlying GaAs) by the steps of (a) anodizing a compound semiconductor to produce a layer thereon of native semiconductor oxide, (b) reducing the layer of oxide at elevated temperature and allowing the more volatile element of the reduced oxide to evaporate away, to leave predominantly the less volatile element overlying the compound semiconductor, (c) depositing an anodizable metal on the surface of the less volatile element, (d) re-anodizing the resulting structure until oxidation has proceeded to beyond the layer containing predominantly the less volatile element and from 10 A to 50 A into the compound semiconductor, and optionally at any suitable stage (e) applying an ohmic contact to the back surface of the compound semiconductor or selectively to the top surface as required.

Abstract: A method of anodizing a compound semiconductor comprises(1) plating a metal on the compound semiconductor,(2) contacting the exposed surface of the metal with an electrolyte which permits anodic oxidation of the metal, and(3) passing an electric current through the electrolyte with the exposed surface of the metal acting as an anode, the current density not exceeding 100 microamps per square centimeter of the surface and the quantity of current being more than sufficient to oxidize anodically all the metal.