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Open access

Hai Liu, Maiying Zhong and Rui Yang

Abstract

This paper deals with the problem of robust fault detection (FD) for an unmanned aerial vehicle (UAV) flight control system (FCS). A nonlinear model to describe the UAV longitudinal motions is introduced, in which multiple sources of disturbances include wind effects, modeling errors and sensor noises are classified into groups. Then the FD problem is formulated as fault detection filter (FDF) design for a kind of nonlinear discrete time varying systems subject to multiple disturbances. In order to achieve robust FD performance against multiple disturbances, simultaneous disturbance compensation and H1/H optimization are carried out in designing the FDF. The optimality of the proposed FDF is shown in detail. Finally, both simulations and real flight data are applied to validate the proposed method. An improvement of FD performance is achieved compared with the conventional H1/H-FDF.

Open access

Xiaopeng Wei, Boxiang Xiao, Qiang Zhang and Rui Liu

A Method of Hyper-sphere Cover in Multidimensional Space for Human Mocap Data Retrieval

A method of hyper-sphere cover in multidimensional space for human Mocap (Motion Capture) data retrieval is presented in this paper. After normalization and feature extraction, both the retrieval instance and the motion data are mapping into a multidimensional space. Several hyper-spheres are constructed according to the retrieval instance, and the domain covered by these hyper-spheres can be considered as the distribution range of a same kind of motions. By use of CMU free motion database, the retrieval algorithm has been implemented and examined and the experimental results are illustrated. At the same time, the main contributions and limitations are discussed.

Open access

Guomin Li, Bing Wang, Rui Wang and Huiling Liu

Abstract

Yb3+/Er3+/GZO ceramics have been synthesized with high temperature solid-state method. The phase and structure of the Yb3+/Er3+/GZO ceramics were characterized by X-ray diffraction (XRD). The XRD pattern that following ions Yb3+, Er3+ and Ga3+ were well doped into the ZnO lattice. Effi cient visible up-conversion (UC) red and green emission were observed under 980 nm excitation. The mechanism of the UC luminescence is investigated on the basis of the UC luminescence emission spectra, the power curve and energy level diagram. The infl uence of doping ions to the intensity ratio of red to green is analyzed and high purity of red light (red/green = 29.9) is fi nally obtained.

Open access

Gang Xue, Yanjun Liu, Muqun Zhang, Wei Zhang, Jian Zhang, Huaqing Luo and Rui Jia

Abstract

Hydrofoil is widely used in underwater vehicle for the excellent hydrodynamic characteristics. Currently, researches are mostly about the rigid hydrofoil while the flexible hydrofoil, like the caudal fin, has not been studied adequately. In this paper, the fish was regarded as the bionic object. Then the kinematics model to describe the fish swimming was put forward. A fin-peduncle propulsion mechanism was designed based on the kinematics model to achieve the similar sine curve swimming model. The propulsion mechanism was optimized by Matlab to reduce the deviation between the output curve of the fin-peduncle propulsion mechanism and the ideal motion trajectory. Moreover, the motion phase angles among flexible articulations are optimized to reduce fluid resistance and improve propulsive efficiency. Finally, the fish-like hydrofoil oscillation is simulated by fluid-solid coupling method based on the Fluent. It was shown that the optimized flexible fish-like oscillation could generate the motion that follows the similar law of sine. The propulsive efficiency of oscillating hydrofoil propeller is much higher than that of the screw propeller, and the flexible oscillation has higher propulsive efficiency than the rigid oscillation without obvious fluid resistance increase.

Open access

S. Zheng, Guohao Wu, Suoliang Zhang, Jie Su, Lei Liu, Fang Wang, Rui Zhao and Xiaobing Yan

Abstract

The electronic structures of Hg-doped anatase TiO2 with different O vacancy concentrations were calculated using the first-principles based on the density functional theory. The calculated results show that the forbidden band widths of Hgdoped anatase TiO2 widened along with the increase of O vacancy concentration, which is responsible for the blue shift in the absorption edges. It can be deduced from the present study that the Hg-doped TiO2 samples prepared in the experimental research contain a certain quantity of O vacancies.

Open access

Hui Liu, Xiao Xiao, Chun-Mei Lu, Dong-Lan Ling and Rui-Hong Wei

Abstract

Objective

Mobile health (mHealth) provides an innovative and effective approach to promote prevention and management of coronary heart disease. However, the magnitude of its effects is unclear. The aim of this systematic review was to examine the impact of mHealth-based cardiac rehabilitation outcomes among coronary heart disease patients.

Methods

Medline, CINAHL, Embase, PubMed, Google Scholar, NICE, and Cochrane library were searched for randomized controlled trials published between January 2002 and March 2017 which compared mHealth with conventional cardiac rehabilitation programs among coronary heart disease patients.

Results

Eight articles were included in this review. The impact of mHealth interventions on physical activity, medicine adherence, smoking cessation, level of anxiety, and quality of life was inconsistent among the articles.

Conclusions

Further research is needed to conclusively determine the impact of mHealth interventions on cardiac rehabilitation outcomes. The limitations of the included studies (e.g., inadequate sample size, failure to address the core components of cardiac rehabilitation programs, and lack of theory-based design) should be taken into account when designing future studies.

Open access

Yicun Wen, Rui Zhang, Yu Cang, Jianchao Zhang, Lixiao Liu, Xuhong Guo and Bin Fan

Abstract

The improved one-pot synthesis of dimethyl carbonate and propylene glycol from propylene oxide, supercritical carbon dioxide, and methanol with potassium bicarbonate as the catalyst has been reported in this paper. As far as we know, it is the first time to use potassium bicarbonate only as the catalyst in the production process which is simple and cheap. Satisfactory conversion rate of propylene oxide and yield of the products could be achieved at the optimized conditions with quite a small amount of by-products. Our new method offers an attractive choice for the production of dimethyl carbonate in large-scale industry efficiently and environmental friendly.

Open access

Zhe Zhou, Wenrui Diao, Xiangyu Liu, Zhou Li, Kehuan Zhang and Rui Liu

Abstract

According to previous reports, information could be leaked from GPU memory; however, the security implications of such a threat were mostly over-looked, because only limited information could be indirectly extracted through side-channel attacks. In this paper, we propose a novel algorithm for recovering raw data directly from the GPU memory residues of many popular applications such as Google Chrome and Adobe PDF reader. Our algorithm enables harvesting highly sensitive information including credit card numbers and email contents from GPU memory residues. Evaluation results also indicate that nearly all GPU-accelerated applications are vulnerable to such attacks, and adversaries can launch attacks without requiring any special privileges both on traditional multi-user operating systems, and emerging cloud computing scenarios.