Volume 2 Issue 3
Authors: Jun Zhang; Frank Liou
Abstract: In a blown powder metal deposition process, a multi-axis hybrid manufacturing system, including a material deposition and a material removal system with more than 3-aixs mobility, is highly desirable in the building complex parts. However, the multi-axis planning process is quite complex. In order to address this issue, a parametric representation of STL-based layer geometry is presented in this paper for a multi-axis material deposition and removal process to build a fully functional part without support structures. This multi-axis process can build 3-D layers in which layer thickness is not uniform. By utilizing the advantage of five-axis motion to build non-uniform 3-D layers, the ability to deposit material without support structures is increased. However, in some cases, the deposition process cannot produce the desired geometry of a 3-D layer, and thus the machining process is needed. The algorithms presented in this paper reconstruct the parametric curve from the STL format for the machining process to achieve the desired accuracy by interpolating more points between given points.
Keywords: Process planning; Additive Manufacturing; Hybrid
Authors: Makoto Katoh; Tasuku Kumagai; Takayuki Ozeki
Abstract: This paper presents the concepts and tests of a Flettner rotor vehicle model on a track that can travel safely in a straight line under constant wind force conditions using rotor power. It also discusses emergency operational procedures, primarily a main rotor trip (MRT) function that immediately disengages the rotor from the power train, and a runback (rapidly reducing system loading) feature that can be implemented when the rotor stalls or when other dangerous operating conditions suddenly appear. While such procedures are necessary for the safe operation of this type of vehicle, there are also economic considerations that may make it necessary to halt or rapidly curtail rotor rotation. In our simulations and experiments, we use a stall detector to show the utility of our novel MRT and runback procedures using the moving average method, and compare it to methods that govern low vessel velocities using threshold speed data. The results of our experiments showed that symptom-based control is more appropriate than timing based control. We then analyzed the merits, demerits, risk and countermeasure (MDRC) aspects of both policies. While a concrete guiding principle for risk counter-measures has yet to be determined, the eventual result is expected to be a fusion of the two policies.
Keywords: Flettner rotor vehicle; Rotor speed control; MRT and runback; MDRC
Authors: Chunmao Ma; Yanjun Shao; Ruilin Ma
Abstract: Aiming at the difficulty of equipment fault prediction, by the combination of the validity principles and based on the grey model GM (1, 1) and linear regression model (LRM), a new combined model was established. The model was fitted by two models. It used the original data coming from constant duration measurement to simulate and predict when the system reaches the upper limit of failure data, and according to this to infer the system failure time. At the same time, the metabolism method was introduced to improve the prediction accuracy. At last, an example that output voltage of a certain type of radar transmitter data was given to verify the effectiveness and practicality of the model in failure predication.
Keywords: Analysis; Equipment Fault Prediction; Metabolism Combined Model