Abstract: A sensor may be to detect a property indicative of a print dead zone caused by a defect of build material to be used for generating the three-dimensional object or a malfunction of a heater that is to heat the build material, a build material distributor that is to provide the material, or a carriage. A processor may be to receive, from the sensor, dead zone data relating to the print dead zone, and to prevent the malfunction of the heater, the build material distributor, or the carriage, or to modify data representing the three-dimensional object to cause the three-dimensional object to be shifted such that three-dimensional object is to be printed outside the print dead zone.

Abstract: A method of heating a surface while fabricating a 3-D object is disclosed wherein a first temperature feedback signal from a first location on the surface is used to control the energy radiated by an energy source during a first stage of the fabrication process. A second temperature feedback signal from a second location on the surface is used to control the energy radiated by an energy source during a second stage of the fabrication process.

Abstract: In an example, a method of anticipating maintenance in a printing device includes determining an inertial reference signal of a printer carriage and measuring a current inertial signal of the printer carriage. The method includes cross-correlating the inertial reference signal with the current inertial signal and determining from the cross-correlating when the current inertial signal is not within a preset confidence interval of the inertial reference signal.

Abstract: A heater may be to heat build material during a three-dimensional print job. A sensor may be to measure a temperature distribution of the build material. A processor may be to obtain first temperature data representing a first temperature distribution of build material associated with normal functioning of the heater. The processor may be to obtain second temperature data representing a second temperature distribution of the build material to be measured by the temperature sensor during the three-dimensional print job. The processor may be to compare the first temperature distribution to the second temperature distribution. The processor may be to determine whether the heater is malfunctioning based on the comparison.

Abstract: A method and apparatus partition a AM build bed of a AM unit into a first virtual build bed and a second virtual build bed. The first virtual build bed is assigned to a first user while the second virtual build bed assigned to a second user. A first digital file for a first object to be generated in the first virtual build bed is received from the first user. A second digital file for a second object to be generated in the second virtual build bed is receive from the second user. Output signals are transmitted to the AM unit to generate the first object in the first virtual build bed and the second object in the second virtual build bed during a build cycle.

Abstract: In one example, a method of controlling generation apparatus for generating a three-dimensional object is described. For example, data indicative of at least one physical property affecting heat transfer from an object may be determined and used to determine a cooling time, and a component of the generation apparatus may be controlled in response to the determined cooling time.

Abstract: The heating of a surface is controlled by: monitoring the temperature of a plurality of zones of the surface to output at least one temperature reading of each of the plurality of zones. The temperature readings are modulated in response to a pattern arranged across a portion of the plurality of zones. The energy delivered to each of the plurality of zones is controlled based on the modulated temperature readings to maintain a substantially homogeneous temperature distribution across the surface.

Abstract: Method and apparatus for sending and receiving data in a wireless machine to machine communication network comprising at least a gateway (2) and a plurality of nodes (4), implementing an hybrid Medium Access Control protocol to access the shared medium. In order to prevent collisions when sending data transmissions (26), nodes (4) request access to the medium with access request packets (25), and are informed by the gateway (2) if said access request packets (25) are received correctly or if a collision occurred. According to the feedback information (24) provided by the gateway (2), nodes (4) are organized in a distributed queuing system with separate queues collision resolutions and data transmissions (26). Time slots (19) with fixed length are used, divided into three separate subperiods for feedback information (24), access request packets (25) and data transmissions (26). The method and apparatus further implements channel hopping to reduce interferences from adjacent networks.