University of Macau

About: University of Macau is a education organization based out in Macao, Macau, China. It is known for research contribution in the topics: Computer science & Population. The organization has 6636 authors who have published 18324 publications receiving 327384 citations. The organization is also known as: UM & UMAC.

Prescribed Performance Observer-Based Adaptive Fuzzy Control for Nonstrict-Feedback Stochastic Nonlinear Systems

Abstract: This paper focuses on an observer-based adaptive fuzzy control problem for nonstrict-feedback stochastic nonlinear systems with input saturation and prescribed performance. By introducing a mean-value theorem, the obstacle arising from input saturation is overcome. The transient performance of system output is also achieved by means of designing performance function. On the other hand, a variable separation method is used to deal with the difficulty caused by nonstrict-feedback structure. Additionally, fuzzy logic systems are introduced to approximate unknown nonlinear functions. Moreover, an observer is constructed to estimate unknown state variables in the systems. By combining adaptive backstepping control method, an observer-based adaptive fuzzy controller is designed to ensure all signals of the resulting closed-loop system to be bounded, and the output of the system converge to a prescribed area. Finally, two examples are given to show the effectiveness of the proposed control scheme.

Designing an Efficient Image Encryption-Then-Compression System via Prediction Error Clustering and Random Permutation

Abstract: In many practical scenarios, image encryption has to be conducted prior to image compression. This has led to the problem of how to design a pair of image encryption and compression algorithms such that compressing the encrypted images can still be efficiently performed. In this paper, we design a highly efficient image encryption-then-compression (ETC) system, where both lossless and lossy compression are considered. The proposed image encryption scheme operated in the prediction error domain is shown to be able to provide a reasonably high level of security. We also demonstrate that an arithmetic coding-based approach can be exploited to efficiently compress the encrypted images. More notably, the proposed compression approach applied to encrypted images is only slightly worse, in terms of compression efficiency, than the state-of-the-art lossless/lossy image coders, which take original, unencrypted images as inputs. In contrast, most of the existing ETC solutions induce significant penalty on the compression efficiency.

Current Progresses of Exosomes as Cancer Diagnostic and Prognostic Biomarkers.

Abstract: Cancer related exosomes are nano-size membrane vesicles that play important roles in tumor microenvironment. Emerging evidence indicates that exosomes can load unique cargoes, including proteins and nucleic acids that reflect the condition of tumor. Therefore, exosomes are being used as diagnostic and prognostic biomarkers for various cancers. In this review, we describe the current progresses of cancer related exosomes, including their biogenesis, molecular contents, biological functions, sources where they are derived from, and methods for their detection. We will also discuss the current exosomal biomarkers and the utilization of them for early diagnosis and prognostics in cancer.