Papers by Keyword: Root Mean Square (RMS)

Abstract: Magnetic Barkhausen noise (MBN) is a new technique on non-destructive testing of residual stress. The testing system based on virtual instrument was explored. It can achieve the MBN and deal with it in time. The technique is applied to analyze residual stress in the welding line of iron materials back and forth the heat treatment. Through comparing with the data of blind-hole method, the corresponding change between Barkhausen signals and residual stress is verified.

Abstract: With the development of computational technology, neural network has attracted the more and more attentions to reveal the relationships between the process parameters and welding geometry. However, the Gas Metal Arc (GMA) welding is complex and of multiple interactions so that mathematical model for welding parameters has not been achieved. Neural networks have been noted as being particularly advantageous for modeling systems which contain noisy, fuzzy and uncertain elements, while a sufficient algorithm is employed. In this study, Levenberg-Marquardt algorithm was employed into GMA welding process. Mahalanobis Distance (MD) was measured to determine the on-line welding quality to avoid joint failure as welding quality. To get an optimal neural network, cases with different configurations were carried out. The Root of the Mean sum of Squared (RMS) error was adopted to evaluate the accuracy of the prediction by neural networks with LM algorithm. The results presented that the proposed algorithm had the superiority of high accuracy that can be used in the on-line welding process.

Abstract: Elliptical vibration cutting (EVC) process and three dimensional cutting surfaces are analyzed in this paper to understand the formation of surface topography. The model of EVC surface topography is established based on curved surface remove function under the assumption that the tool edge is sharp enough. And simulation analysis of surface topography is conducted with different feed offset ratios. Results indicate that RMS change with feed offset ratios λ. The range of RMS is larger when feed offset ratio ranges from both 0 to 0.4 and 0.6 to 1, while the range is smaller when feed offset ratio changes from 0.4 to 0.6. Whats more, RMS reaches the minimum when feed offset ratio is 0.5. The present research provides some references for reducing the height of vibration ripples and improving EVC surface quality.

Abstract: According to the surface formation mechanism of elliptical vibration cutting (EVC), EVC process and three dimensional cutting surfaces are analyzed in this paper. The model of EVC surface topography is established based on curved surface remove function under the assumption that the tool edge is sharp enough. Simulation analysis of surface topography is conducted to verify the established model. The present research clarifies the law that cutting parameters influent on EVC surface topography. Whats more, it provides some references for optimizing the selection of EVC cutting parameters and further improving EVC surface quality.

Abstract: To solve the problem of long time consuming in the fractal encoding process, a fast fractal encoding algorithm based on RMSE (Root mean square error) and DCT (Discrete Cosine Transform) classification is proposed. During the encoding process, firstly, the image is divided into range blocks and domain blocks by quadtree partition according to RMSE, then, according to DCT coefficients of image block, three classes of image blocks are defined, which are smooth class, horizontal/vertical edge class, diagonal/sub-diagonal class. At last, every range block is limited to search the best matched block in the corresponding domain block class, and the fractal coding are recorded until the process is completed. When searching the best matched block, the nearest neighbor block will be found in the sense of RMSE in the ordered codebook, and the best matched block will be further found in the vicinity of the nearest neighbor block. The experimental results show that the proposed algorithm can efficiently reduce the search space and shorten the encoding time, while achieving the same reconstructed image quality as that of the full search method.

Abstract: A novel design of data acquisition system based on CPLD and DSP coordination control is presented. Verilog HDL is adopted in this system to realize the function of Schmitt trigger on CPLD. Combining with the method of zero-crossing detection, the RMS of signal voltage, current and frequency are effectively calculated. Experimental results indicate that the given method has improved the detection efficiency and computational accuracy.

Abstract: According to the perturbation in lithography positioning control system, a novel gain scheduled PID controller using a root mean square (RMS) signal is proposed. Perturbation is also referred as the stage hunting, and the positioning control system will be very weak against small disturbances such as electrical noise or even structural vibration of the building in which the stage is installed. The gain scheduled PID controller is used to minimize the stage hunting and simultaneously maximize the immunity to disturbances. Simulations results verify the effectiveness of the gain scheduled PID controller for the positioning control in the lithography stage, as compared with the traditional PID controller.

Abstract: Regional wind power forecasting deals with the prediction of the aggregated power output of wind farms located within a defined region. By architecture, regional forecasting models are classed by three approaches. In these approaches, the cascaded approach is a most practical method although the method has a larger prediction error. This paper provides a systematic review of all these regional forecasting approaches and ultimately proposes an advanced cascaded method to improve forecasting precision. The method use root mean square error as evaluation criteria to adjust every prediction of signal wind farm in a region. The simulation results show the effectiveness of the advanced cascaded method.

Abstract: Elevation control survey was the foundation of the surveying for ancient architecture profile and facade. The traditional survey method of closed leveling line had many defects such as its workload was big; its calculating office work was complex and so on. The new method used many control points existing in reality, then sublevel surveyed independently. The new method also used the traditional adjustment method and weighting adjustment method. It accelerated the survey progress and increased the survey precision.

Abstract: This study clarifies the fatigue properties using global signal statistical approach during the crack initiation stage for metallic component. Strain loading and acoustic emission (AE) signatures are captured simultaneously in the form of signal waves recorded by strain gauge and AE transducer. An initial study was carried out in the laboratory on medium carbon AISI 1045 steel specimens at constant amplitude cyclic loading condition, which lead to the fatigue failure characteristics. This study was carried out to investigate the relationship between strain and AE signals in order to make sure that AE technique also can be used as a detecting and monitoring crack initiation in metallic specimens. To achieve the goal, three different loads were applied on three specimens to capture the differences of the signals. The specific data acquisition systems were used to collect strain and AE signatures. For the purpose of analysis, the method of root mean square (r.m.s) and the kurtosis were used. The r.m.s value was used to quantify the overall vibrational energy content whereas the kurtosis was then used because of its sensitivity to high amplitude events. Based on these statistical approaches, the correlation patterns between both signals are expected to give a meaningful baseline to predict and monitor crack initiation of a metallic specimen.