Zixi Wang

Robot-aided sensorimotor arm training methods based on neurological rehabilitation principles in stroke and brain injury patients

We developed the upper extremity compound movements (UECM) rehabilitation training robot and designed straight-line paths tracking and circle paths tracking exercise based on neurological rehabilitation principles. Rehabilitative exercises should be on hand paths rather than on individual joints, robot can guide patients during forward reaching movements. The exterior oriented circle movement performed the coactivation of shoulder abductors with elbow extensors and the coactivation of shoulder adductors with elbow flexors at most of tracks against the stereotypic movement pattern in stroke and brain injury

Frequency Analysis of the Orbit Responses of Active Magnetic Bearings in Touchdown Using Hilbert Transform

Touchdown bearing (TDB) is one of the key elements in active magnetic bearings (AMBs). When the magnetic bearing fails or is exposed to an overload, touchdown events will occur. According to ISO 14839, three typical orbit responses (pendulum vibration, combined rub and bouncing, and full rub) can be detected in touchdown events. The magnitude of the dynamic forces between the rotor and TDBs has been considered as an indicator to identify these orbit responses. However, the contact forces may not be easy to measure with precision. The instantaneous frequency of the rotor vibration is another significant difference between them. In this paper, a performance analysis model has been established that considers the dynamic and thermal effects in touchdown events. Simulations under different working conditions have been conducted and a recommendation for safety working conditions of the AMB system has been developed. The instantaneous frequency of the rotor vibration has been computed using Hilbert transform and...

Tests to evaluate the ecological impact of treated ballast water on three Chinese marine species

Ballast water has been a topic of concern for some time because of its potential to introduce invasive species to new habitats. To comply with the International Convention for the Control and Management of Ships’ Ballast Water and Sediments, members of the International Maritime Organization (IMO) must equip their ships with on-board treatment systems to eliminate organism release with ballast water. There are many challenges associated with the implementation of this IMO guideline, one of which is the selection of species for testing the ecological impacts of the treated ballast water. In the United States, ballast water toxicity test methods have been defined by the United States Environmental Protection Agency. However, the test methods had not been finalized in China until the toxicity test methods for ballast water were established in 2008. The Chinese methods have been based on species from three trophic levels: Skeletonema costatum, Neomysis awatschensis, and Ctenogobius gymnauchen. All three species live in broad estuarine and open sea areas of China; they are sensitive to reference toxicants and acclimatize easily to different conditions. In this paper, the biological characteristics, test processes and statistical analysis methods are presented for the three species. Results indicate that the methods for evaluating these three organisms can be included in the ecological toxicity tests for treated ballast water in China.

Influence of Inactivation Treatment of Ship's Ballast Water on Corrosion Resistance of Ship Steel Plate

The effect of seawater after ultraviolet inactivation on corrosion of a shipbuilding steel plate was investigated by means of natural corrosion potential experiments and immersion corrosion lest. The effects of natural seawater and treated seawater after ultraviolet inactivation on corrosion of the selected steel plate samples were compared with each other. The results showed that there was no obvious change in the chemical composition of treated seawater compared with natural seawater. The corrosion potential slightly increased by 10 m V, whereas the corrosion rate rose significantly by 20%. The experiments verified the naturally formed biofilm in the natural seawater for the inhibition of corrosion on the shipbuilding steel plate. The possible influences of ballast water treatment on biofilm by ultraviolet and electrolysis inactivation under the condition of practical usage were also investigated. And it was found that ballast water treatment methods with no continuous disinfection could protect original tank biofilm structure, reducing the intensity of tank corrosion.