Monte Carlo analysis of the effect of uncertainties on model-based HVAC fault detection and diagnostics

Wang, Liping,Haves, Philip Taylor Francis 2014 HVAC&R research Vol.20 No.6

Bioinspired Fabric with Superhydrophilicity and Superoleophobicity for Efficient Oil/Water Separation

Liping Liang,Chenlu Wang,Hongfang Wang,Haihua Zhan,Xu Meng 한국섬유공학회 2018 Fibers and polymers Vol.19 No.9

The cotton fabric was modified with dopamine methacrylamide (DMA) based on mussel-inspired reaction and polymerized with zwitterionic sulfobetaine methacrylate (SBMA) through free radical polymerization reaction. The poly(DMA-SBMA) contained not only key chemical constituents of dopamine hydrochloride, which strongly adsorbed to fabric substrates, but also hydrophilic groups, providing a hydrophilic surface for fabric due to its strong interaction with water via electrostatic interactions. The chemical structure, surface topography, and surface wettability of the fabric were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and contact angle experiments, respectively. The results showed that the water contact angle (WCA) of the treated fabric was ~0 o, whereas the underwater oil contact angle (OCA) was ~161 o, as compared to ~25 o for the control one. It is expected that as-prepared fabrics could be applied in oil/water separation due to such special superhydrophilicity and superoleophobicity.

Boundary Output Feedback Stabilization of the Linearized Schrödinger Equation with Nonlocal Term

Liping Wang,Feng-Fei Jin 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.4

In this paper, we are concerned with the boundary output feedback stabilization problem of a Schrödingerequation with a nonlocal term. Firstly, we design an explicit boundary state feedback controller by backsteppingapproach. Under this controller, the closed-loop system is proved to be exponentially stable from the equivalencebetween the original system and the target system. Then, we propose an observer-based output feedback controllerby replacing the state in state feedback controller with its estimation. The resulting closed-loop system admitsa unique solution which is exponentially stable. Finally, some numerical examples are presented to illustrate theeffectiveness of the proposed feedback controller.

Post-Processing for JPEG-Coded Image Deblocking via Sparse Representation and Adaptive Residual Threshold

( Liping Wang ),( Xiao Zhou ),( Chengyou Wang ),( Baochen Jiang ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.3

The problem of blocking artifacts is very common in block-based image and video compression, especially at very low bit rates. In this paper, we propose a post-processing method for JPEG-coded image deblocking via sparse representation and adaptive residual threshold. This method includes three steps. First, we obtain the dictionary by online dictionary learning and the compressed images. The dictionary is then modified by the histogram of oriented gradient (HOG) feature descriptor and K-means cluster. Second, an adaptive residual threshold for orthogonal matching pursuit (OMP) is proposed and used for sparse coding by combining blind image blocking assessment. At last, to take advantage of human visual system (HVS), the edge regions of the obtained deblocked image can be further modified by the edge regions of the compressed image. The experimental results show that our proposed method can keep the image more texture and edge information while reducing the image blocking artifacts.

Image Deblocking Scheme for JPEG Compressed Images Using an Adaptive-Weighted Bilateral Filter

Wang, Liping,Wang, Chengyou,Huang, Wei,Zhou, Xiao Korea Information Processing Society 2016 Journal of information processing systems Vol.9 No.3

Due to the block-based discrete cosine transform (BDCT), JPEG compressed images usually exhibit blocking artifacts. When the bit rates are very low, blocking artifacts will seriously affect the image's visual quality. A bilateral filter has the features for edge-preserving when it smooths images, so we propose an adaptive-weighted bilateral filter based on the features. In this paper, an image-deblocking scheme using this kind of adaptive-weighted bilateral filter is proposed to remove and reduce blocking artifacts. Two parameters of the proposed adaptive-weighted bilateral filter are adaptive-weighted so that it can avoid over-blurring unsmooth regions while eliminating blocking artifacts in smooth regions. This is achieved in two aspects: by using local entropy to control the level of filtering of each single pixel point within the image, and by using an improved blind image quality assessment (BIQA) to control the strength of filtering different images whose blocking artifacts are different. It is proved by our experimental results that our proposed image-deblocking scheme provides good performance on eliminating blocking artifacts and can avoid the over-blurring of unsmooth regions.

Synthesis and Characterization of pH-sensitive and Self-oscillating IPN Hydrogel in a pH Oscillator

Liping Wang,Jie Ren,Xiaoyan Zhang,Xiaoci Yang,Wu Yang 한국고분자학회 2015 폴리머 Vol.39 No.3

A self-oscillating interpenetrating polymer network (IPN) poly(acrylic acid)/poly(ethylene glycol) (PAA/PEG) hydrogel was prepared by using radical polymerization with a two-step method. The IPN hydrogel was characterized by FTIR spectroscopy and morphological analysis. The results indicated that the chains of PEG and PAA twined to form porous structure which is beneficial to water molecules entering inside of the hydrogel. In addition, the pH-responsive behavior, salt sensitivity, swelling/de-swelling oscillatory behaviors and self-oscillation in a closed pH oscillator were also studied. The results showed that the prepared hydrogel exhibited pH-sensitivity, good swelling/de-swelling reversibility and excellent salt sensitivity. The self-oscillating behavior of swelling/de-swelling for the prepared hydrogel was caused by pH alteration coupled with the external media. This study may create a new possibility as biomaterial including new self-walking actuators and other related devices.

Kinematic performance analysis and promotion of a spatial 3-RPaS parallel manipulator with multiple actuation modes

Liping Wang,Zhaokun Zhang,Zhufeng Shao 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.2

This paper presents a 3-RPaS (R and S denote the revolute and spherical joint, pa denotes the parallelogram) parallel manipulator with two-rotational-degrees-of-freedom (2R1T) and one-translational-degree-of-freedom motion. By introducing parallelograms and an innovative driving module, the 3-RPaS manipulator can change the transmission path of the driving and reaction forces, and achieves 27 actuation modes. The kinematic performance of the manipulator under different actuation modes is analyzed with the indices that are defined based on matrix orthogonal degree. Comparative analysis indicates that the kinematic performance of the manipulator varies significantly in different actuation modes. A reasonable selection of actuation modes can effectively improve the kinematic performance and eliminate singularities. The concept of optimal actuation mode and the implementation approach of actuation mode conversion are discussed and analyzed for kinematics promotion. The kinematic performance of the manipulator is greatly improved with optimal actuation modes, without changing the topology structure and dimensional parameters.

Blind Image Quality Assessment on Gaussian Blur Images

Wang, Liping,Wang, Chengyou,Zhou, Xiao Korea Information Processing Society 2017 Journal of information processing systems Vol.13 No.3

Multimedia is a ubiquitous and indispensable part of our daily life and learning such as audio, image, and video. Objective and subjective quality evaluations play an important role in various multimedia applications. Blind image quality assessment (BIQA) is used to indicate the perceptual quality of a distorted image, while its reference image is not considered and used. Blur is one of the common image distortions. In this paper, we propose a novel BIQA index for Gaussian blur distortion based on the fact that images with different blur degree will have different changes through the same blur. We describe this discrimination from three aspects: color, edge, and structure. For color, we adopt color histogram; for edge, we use edge intensity map, and saliency map is used as the weighting function to be consistent with human visual system (HVS); for structure, we use structure tensor and structural similarity (SSIM) index. Numerous experiments based on four benchmark databases show that our proposed index is highly consistent with the subjective quality assessment.

Image Deblocking Scheme for JPEG Compressed Images Using an Adaptive-Weighted Bilateral Filter

( Liping Wang ),( Chengyou Wang ),( Wei Huang ),( Xiao Zhou ) 한국정보처리학회 2016 Journal of information processing systems Vol.12 No.4

Due to the block-based discrete cosine transform (BDCT), JPEG compressed images usually exhibit blocking artifacts. When the bit rates are very low, blocking artifacts will seriously affect the image`s visual quality. A bilateral filter has the features for edge-preserving when it smooths images, so we propose an adaptiveweighted bilateral filter based on the features. In this paper, an image-deblocking scheme using this kind of adaptive-weighted bilateral filter is proposed to remove and reduce blocking artifacts. Two parameters of the proposed adaptive-weighted bilateral filter are adaptive-weighted so that it can avoid over-blurring unsmooth regions while eliminating blocking artifacts in smooth regions. This is achieved in two aspects: by using local entropy to control the level of filtering of each single pixel point within the image, and by using an improved blind image quality assessment (BIQA) to control the strength of filtering different images whose blocking artifacts are different. It is proved by our experimental results that our proposed image-deblocking scheme provides good performance on eliminating blocking artifacts and can avoid the over-blurring of unsmooth regions.

The Effects of Image Dehazing Methods Using Dehazing Contrast-Enhancement Filters on Image Compression

( Liping Wang ),( Xiao Zhou ),( Chengyou Wang ),( Weizhi Li ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.7

To obtain well-dehazed images at the receiver while sustaining low bit rates in the transmission pipeline, this paper investigates the effects of image dehazing methods using dehazing contrast-enhancement filters on image compression for surveillance systems. At first, this paper proposes a novel image dehazing method by using a new method of calculating the transmission function―namely, the direct denoising method. Next, we deduce the dehazing effects of the direct denoising method and image dehazing method based on dark channel prior (DCP) on image compression in terms of ringing artifacts and blocking artifacts. It can be concluded that the direct denoising method performs better than the DCP method for decompressed (reconstructed) images. We also improve the direct denoising method to obtain more desirable dehazed images with higher contrast, using the saliency map as the guidance image to modify the transmission function. Finally, we adjust the parameters of dehazing contrast-enhancement filters to obtain a corresponding composite peak signal-to-noise ratio (CPSNR) and blind image quality assessment (BIQA) of the decompressed images. Experimental results show that different filters have different effects on image compression. Moreover, our proposed dehazing method can strike a balance between image dehazing and image compression.