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Generation of a quiet zone in noisy environment is undoubtedly of considerable realistic significance. This paper describes development and implementation of a multichannel real-time active noise control (ANC) system for 3 dimensional noisy environment to enhance the quiet zone performance in terms of size and noise cancellation gain. The proposed ANC system employes a multichannel delay-compensated filtered-X least mean square (FXLMS) algorithm; its real-time implementation is designed in TMS320C6713 digital signal processor (DSP) board. The system is evaluated for cancelling various tonal frequency noises in the range from 100 to 500 Hz, and the performance is then illustrated by measuring the quiet zone in terms of sound pressure level (SPL) attenuation. Experiment results show that a quiet zone of quiet with satisfactory size and maximum 24 dB noise attenuation is successfully generated.

Generating a quiet zone at a target location is the ultimate goal of active noise control (ANC). Generally, the best noise cancellation is achieved at the locations of error sensors. However, the distribution of physical error sensors at a given location is not always convenient or feasible. To overcome this challenge, a number of virtual sensing algorithms for ANC have been researched. Using the physical error signals and knowledge of the system, the adaptive least mean square (LMS) virtual sensing algorithm estimates the error signal at a location that is remote from the physical error sensor, referred to as the virtual location. It achieves excellent performance under the assumption that the unknown primary path is fixed, but its performance decreases significantly if the path is constantly changing. This paper presents a real-time ANC system with an improved virtual sensing algorithm to solve this problem. The proposed system was tested to enhance the quiet zone in a constantly changing environment; an enhanced quiet zone was created, and the noise cancellation, especially at the target location, obviously improved.Electronics 2017, 6, 76 2 of 13 sensing algorithm cannot maintain excellent performance. This paper presents a modified adaptive LMS algorithm to solve this problem. The proposed algorithm achieves the microphone weights on the basis of the secondary paths, the secondary paths are fixed during the system operation. Thus, the proposed algorithm effectively eliminates the influence of a constantly changing primary path. A multichannel ANC with an improved virtual sensing algorithm was then designed to enhance the noise cancellation at the target location.The organization of this paper is as follows: Section 2 presents the design of real-time multichannel ANC system. In Section 3, the adaptive LMS virtual sensing algorithm is introduced and the improved adaptive LMS virtual sensing algorithm is proposed. Experimental results are presented in Section 4, and the conclusions are summarized in Section 5. Multichannel Real-Time ANC SystemThe filtered-x least mean square (FXLMS) algorithm has been widely used in practical ANC due to its robustness and simplicity. In our proposed system, the multichannel delay-compensated FXLMS algorithm is applied [22], it achieves a faster convergence rate and better performance with only double computation load, and this guarantees the possibility of real-time implementation. The multichannel delay-compensated FXLMS is illustrated in Figure 1. It employs I reference sensors to form the reference signal vector, generates J canceling signals to drive the corresponding secondary sources, and distributes K error sensors over desired locations to measure the residual noise components.Electronics 2017, 6, 76 2 of 12 achieves the microphone weights on the basis of the secondary paths, the secondary paths are fixed during the system operation. Thus, the proposed algorithm effectively eliminates the influence of a constantly changing primary path. A multichannel ANC with an improv...

The automated visual inspection system (machine vision system) for quality assurance is important factory automation equipment in the manufacturing industries, such as display, semiconductor, etc. There is a lot of demand for the machine vision engineers. However, there are no technical training courses for machine vision technologies in vocational schools, colleges and universities. In this paper, we present the implementation of line scan camera based equipment for technical training of the automated visual inspection system. The training system consists of the X-Y stage which is widely used in machine vision industries and its variable image resolution are set to 10-30 μm. Additionally, this training system can attach the industrial illumination, either the direct illuminator or coaxial illuminator, for verifying the effect of illuminations. This means that the trainee can have a practical training in various equipment conditions and the training system is similar to the automated visual inspection system in industries.

, the new version of Long-term Education Reform and Development Plan was released, which clearly states: "In school education, we must adhere to moral education first and integrate socialist core values into the entire national education. The state defines moral education as a strategic issue in national education, from which we can see the importance of moral education in China. With the Chinese dream proposed, strengthening the social responsibility of college students and developing their eagerness to realize national revival are of great significance in current moral education in colleges and universities.