Applied Mechanics and Materials Vols. 325-326

Abstract: The paper presents a compensator design technique for systems with saturating actuators in order to recover as much as possible the performance of the unsaturated case. This anti-windup scheme is obtained using H-infinity optimization methodology. The proposed design approach allows to obtain a anti-windup controller that accounts for time-delays in the control system. Comparative result are presented for the two design methods and time simulation of the nonlinear system are used to analyze the performances of both designs. A reduced order anti-windup controller procedure is also investigated. Keywords: PIO, anti-windup, rate saturation, compensator.

Abstract: This paper presents an automated visual inspection system, which detects defects of medicines including tablets and capsules in Aluminum-plastic blister packaging. The system operates either in training or inspection mode. In training mode, the images of each type defect-free blister pack are used to extract the model. In inspection mode, the type of an inspected blister pack is determined and the defects of the medicines in the blister pack are detected in real-time. In this system, an improved definition of color histogram is adopted to determine the blister pack type correctly, by calculating the distance of the defined color histograms between the inspected image and each model. The eigenvector is designed, which distance could be used to judge the defects of tablet, while the color feature is utilized to detect the defects of capsule. In addition, an effective image skew correction method based on least squares technique is developed. Experiment results show that the system could effectively inspect typical defects of different tablet and capsule.

Abstract: This paper proposes a vision detection algorithm to acquire LIGA part’s edges based on an in-house multi-DOF manipulator for LIGA part assembly. Feature recognition based on maximum information entropy is proposed to solve the problem that high precision edge recognition under backlight source. In order to further improve vision recognition accuracy, edge feature recognition algorithm based on symmetrical edge is proposed to recognize the center line of the symmetrical parts when the quality of the image is poor.

Abstract: Compared with the traditional SVM, LS_SVM improves the speed of the large sample study,however ,LS_SVM loses its sparsity, which is an advantage of the the traditional SVM . For LS_SVM,almost all of the samples are support vectors .When a new sample added all samples are re-involved in the calculation, and that greatly increases the amount of the computation. In response to these issues,this paper presents an algorithm called the LSSVM sliding window pruning algorithm,which is based on DTW. With the combination of local modeling ,the algorithm selects the most similar samples with the current sample point in the process of the establishment of the on-line model of the batch process as the training samples .It can remove those samples that are relatively ineffective,which can restore LSSVM 's sparsity.Taking the cell concentration in the fermentation process of E. Coli for example, this paper proves that the method can establish a more accurate on-line prediction model in the case of a smaller number of samples . Compared with the off-line LSSVM ,the on-line model has a higher accuracy and a better dynamic adaptability.

Abstract: This paper studies the stability of nonlinear model predictive control (NMPC) based on sub-optimal solution obtained under reduced precision solution (RPS) criteria. NMPC needs to solve the optimal control problem (OCP) quickly and the input is injected into the controlled plant in time. Traditional convergence criteria in optimization algorithms usually cost excessive long computation time with little improvement of solution, which results in degradation of control performance eventually. RPS criteria are new convergence criteria for deciding whether the current iterate is good enough and whether the optimization procedure should be terminated. It can terminate the optimization process timely. This work gives the proof of the rps-NMPCs property. Simulations are done to analyze the effect of disturbance, especially when computational delay exists, on the closed-loop system controlled by rps-NMPC, and demonstrate that the algorithm owns good stability when disturbance exists.

Abstract: The main purpose of this paper is to propose an incorporating a genetic algorithm (GA) into the Operation Tree (OT), called GAOT, and apply it to estimate the compressive strength of high-performance concrete (HPC). A large number of experimental data were used to compare accuracies of the model building technique. The results show that this novel model, GAOT, can obtain highly nonlinear mathematical equations with low estimating errors for predicting the compressive strength of HPC.

Abstract: Detailed finite element analysis has been carried out for different bollard supporting structures by ANSYS software. From the analysis results, it can be seen that the bollard supporting structures are of adequate strength to take the design load transferred from the mooring rope during operation considering the requirement on strength criteria from IACS, and strength check is performed in accordance with the updated relevant ABS standard. Finally, a comparison of these different bollard supporting structures is made to find out their own advantages from safety and other aspects.

Abstract: In acoustic emission (AE) testing for steel structures, location of AE source is an important problem because the source is often related to micro-structure change or defects. In the paper, an activity detector was proposed to locate AE sources based on clustering analysis and AE statistical parameters. Firstly, a location plane, which may contain AE sources, was obtained by the technique of time difference of arrival (TDOA). And the plane was divided into some sub-planes base on clustering analysis. Then, the activity detector was established based on two AE statistical parameters of energy counts and ring-down counts. Finally, the detector value in each sub-plane was calculated and the sub-plane with the maximum value was identified the position of AE sources. Further, by applying the method to test crack sources in a steel structure experiment, the crack position was located correctly compared with actual crack sources. The results demonstrated that the method based on the AE activity detector can reduce ambiguity and locate AE sources accurately and effectively.

Abstract: Growing construction activities requires increase in construction materials. The conventional method of constructions results in a rise in construction waste. Formwork as a main factor to generate construction waste has been the topic of investigation. The permanent formwork has been introduced with the aim to: promote the construction technology process that put quality, safety and environment issues into account, reduce the cost of workers and reduce the overall time of construction project. At present the permanent formwork available in the market are made from steel, and plastic and the cost is still high. Therefore this study is looking at the potential of commercial wood-wool cement board (WWCB) as permanent formwork. A series of concrete columns were constructed with and without integrated WWCB with different configurations of WWCB as permanent formwork. These columns were subjected to axial load and the compressive strength and failure modes were recorded. The results show that the present of permanent formwork from WWCB improves the compressive strength of the column. With the permanent formwork, the size of concrete column can be reduced and able to support the same load as column without permanent formwork. Therefore this construction method can reduce the overall cost of construction.

Abstract: As the Water-retaining Structure of reservoir, Earth-Rock Dam was widely used because of a wide accommodation, local material and rapid construction speed .There are 86 thousand dams having been built in our country, 90% of which are earth-rockfill dams. However, the aging and disease of earth-rockfill dams are becoming more and more serious. As time goes by, its security problem gets more and more attention. The risk management of dam is a kind of new concept of safety management which is brought in from abroad. One of the most prominent characteristics is that it is conscious both of its own safety and the effect of downstream, which effectively overcomes the deficiency of today's management mode, and it has practical significance to improve earth-rockfill dams management level , ensuring construction and public safety. The study gives the analysis of the economic developments effect on the dam-break loss, and establishes the dynamic predication evaluation model based on uncertainty theory. The model can effectively reflect the time variant characteristics of dam-break loss, which provides new attempt to dynamic predication of dam-break loss.