Analysis and design of electromagnetic vibration and noise reduction method of permanent magnet motor

Vibration and noise parameters have a significant influence on the performance of permanent magnet motor (PMM). A new method of reducing vibration and noise of PMM was proposed in this study by optimizing the stator teeth profile. The optimal offset distance was determined by finite element method, and the results indicate that the vibration and noise amplitude become larger when the frequency is an even multiple of the fundamental frequency. The maximum and average vibration acceleration of the optimized PMM is reduced by 22.27% and 11.11%, respectively, and the total sound pressure level (SPL) is decreased by 3.67%. Finally, the correctness of the theoretical parameters was verified by the vibration and noise measuring experiment. The experimental data suggest that the average acceleration error is 7.07%, and the average SPL error is 2.28%. The research methods and conclusions of this study may be extended to the vibration and noise optimization of other PMM.

A Study of the Aerodynamic Characteristics of the Rocket Fairing Door Using Conical Means of Passive Stabilization

In the article, the aerodynamic characteristics of a detachable fairing door model are investigated with the use of passive stabilization means, which are conical bodies with flexible and rigid connections. Two types of experiments were conducted in a subsonic wind tunnel to determine the balancing angles of attack: a visualization experiment (using a video camera) and a measuring experiment (using the angle sensor). Mathematical flow models and aerodynamic quality values were obtained. The change in the balancing angle of attack and the corresponding aerodynamic quality of the studied combinations with respect to the base model were analyzed. Comparative characteristics of the considered stabilization variants were presented.

Cellular Automaton Modeling of Phase Transformation of U-Nb Alloys during Solidification and Consequent Cooling Process

The microstructure evolution of U-Nb alloys during solidification and consequent cooling process was simulated using a cellular automaton (CA) model. By using this model, ϒ phase precipitation and monotectoid decomposition were simulated, and dendrite morphology of ϒ phase, Nb microsegregation and kinetics of monotectoid decomposition were obtained. To validate the model, an ingot of U-5.5Nb (wt.%) was produced and temperature measuring experiment was carried out. As-cast microstructure at different position taken from the ingot was investigated by using optical microscope and SEM. The effect of cooling rate on ϒ phase precipitation and monotectoid decomposition of U-Nb alloys was also studied. The simulated results were compared with the experimental results and the capability of the model for quantitatively predicting the microstructure evolution of U-Nb alloys during solidification and consequent cooling process was assessed.

The Layout Measurement Points Prediction and Flatness Calculation for the Antenna Plate After Welding Assembly Based on the RBF Neural Network Model

Due to the effect of the antenna plate flatness on the antenna performances, the flatness is one of the key performance indicators for the planar antenna. Before calculating the antenna plate flatness, the support assembly tools are built, and then measuring experiment for height coordinate values is carrying out on the assembly platform. This paper presents a predictive method that is the Radial Basis Function (RBF) neural network method to obtain the height coordinate values based on fewer measurement points on the antenna plate after welding assembly, and the antenna plate flatness is calculated by fitting least square plane using measuring point coordinate value through the least square method (LSM). Simultaneously, before or after welding assembly, comparing with the calculated flatness value, it is shown that the calculated flatness value by the predicted height coordinate values basically agrees well with the initial calculated flatness value. These results reveal that the RBF neural network prediction is adopted to be very correct and valid, which will reduce the measurement cost and improve measurement efficiency in future.

Preparation Measurements and Assessment of Roof Systems

The Institute of Architectural Engineering at the Civil Engineering Faculty TU of Kosice, in its ongoing research, aims to monitor the physical properties of building envelope structures with emphasis placed on hydrothermal problems, at present. The research focuses on the assembly of equipment in climate chambers with their respective sample envelopes and fenestration systems, which are involved in a measuring experiment. The prime aim is to design a logical and transparent system for gathering, evaluating and storing hydrothermal related data. This contribution further illustrates the embedding system of measurement points in installed samples and the system of monitoring their physical properties over an annual period.

Roof Structure Evaluation in Climatic Chamber Module

The paper focuses on the assembly of equipment in experimental climate chambers with their respective sample envelopes and fenestration systems, which are involved in a measuring experiment. The prime aim is to design a logical and transparent system for gathering, evaluating and storing hygrothermal related data. This contribution further illustrates the installation of measurement points in test samples, the system of monitoring their physical properties, measurement results of roof system of the climatic chamber module and vapour barrier influence in roof structure on temperature damping phase shift.