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1

Effects of performance level on lower limb kinematics during table tennis forehand loop

Qian J., Zhang Y., Baker J. S., Gu Y.

Acta of Bioengineering and Biomechanics

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2016

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Vol. 18, no. 3

149--155

EN

Understanding of biomechanics is important in performance development since each skill has a fundamental mechanical structure. The purpose of this study was to investigate differences in lower limb kinematics during table tennis forehand loop between superior players (SP) and intermediate players (IP). Thirteen male players as superior and thirteen as intermediate participated in this test. A VICON motion analysis system and a Novel Pedar insole plantar pressure measurement system were used to record kinematic and contact area data, respectively. Participants were asked to execute single forehand loop against topspin ball with maximal power. Key findings were that SP showed significantly larger hip flexion and knee external rotation at backward-end and larger hip internal rotation and extension at forward-end compared with IP. Contact areas at both events were larger for SP. In addition, SP showed significantly larger joints angular changing rate during forward swing at the ankle and hip. Results indicated that SP possessed better ability of using lower limb drive in forehand loop.

2

Ramet recruitment from different bud types along a grassland degradation gradient in Inner Mongolia, China

Qian J., Busso C. A., Wang Z., Liu Z.

Polish Journal of Ecology

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2015

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Vol. 63, nr 1

38–-52

EN

Since the contribution of total belowground bud bank and different bud types to community regeneration has rarely been explored, the vegetative offspring recruited from different belowground bud types was investigated in four plant communities along a grassland degradation gradient in northeastern China (Inner Mongolia). This gradient, between 1000 and 1500 m a.s.l., has been caused by overgrazing. It is a Leymus chinensis steppe which occupies about 3.0×105 ha. Recruitment from tiller buds was dominant (>80%) in determining the total vegetative offspring density along the whole grassland degradation gradient. However, the proportional contribution of tiller-ramets to total ramet recruitment was significantly greater (P <0.05) during earlier than later stages of grassland degradation, while that of rhizome-ramets showed an opposite pattern. While the percentage contribution and density of root-derived ramets to total ramet density increased significantly (P <0.05) during the late stages of grassland degradation, those of bulb-ramets kept relatively constant along the whole grassland degradation gradient. The relative contribution of hemicryptophytes [i.e., Achnatherum sibiricum, Cleistogenes squarrosa, Festuca ovina, Koeoleria cristata, Poa annua, Stipa grandis] to total plant species richness decreased, while that of geophytes [i.e., Agropyron cristatum, Carex korshinskyi. Leymus chinensis, Allium anisopodium, A. bidentatum, A. tenuissimum, Astragalus galactites, Cymbaria dahurica, Iris tenuifolin, Potentilla acaulis, P. bifurca, Pulsatilla turczaninovii, Serratula chinensis, Thalictrum aquilegifolium] increased with the increases of grassland degradation. Our results showed that as grassland degradation increased, changes in the proportion of tiller-, rhizome- and root-derived ramets with respect to total ramet density determined in turn changes in the proportion of hemicryptophytes and geophytes in the study plant communities.

3

Surface modification of nano-TiN by using silane coupling agent

Cheng G., Luo J., Qian J., Miao J

Materials Science Poland

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2014

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Vol. 32, No. 2

214--219

EN

Titanium nitride (TiN) nano-particles were subjected to graft modification by silane coupling agent (KH-570) via a direct blending method. The hydroxyl groups on the surface of TiN nano-particles can interact with silanol groups [–Si–OCH3] of KH-570 forming an organic coating layer. The covalent bonds (Ti–O–Si) formation was testified by Fourier transform infrared spectra (FTIR) and X-ray photoelectron spectroscopy (XPS). Through transmission electron micrograph (TEM) observations, it was found that KH-570 could improve the dispersibility of nano-TiN particles in ethyl acetate. Thermo gravimetric analysis (TGA) and contact angle measurements indicated that KH-570 molecules were adsorbed or anchored on the surface of nano-TiN particle and the net efficiency of it was 22.76 %, which facilitated to hinder the aggregation of nano-TiN particles.

4

Location-Unaware Node Scheduling Schemes Based on Boundary Nodes in Wireless Sensor Networks

Ma S., Qian J.

Przegląd Elektrotechniczny

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2013

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R. 89, nr 1b

71--74

EN

Node scheduling scheme of sensor nodes is one of the most important method to solve the energy-constrained wireless sensor networks. Traditional methods of node scheduling that without location information leads to a node in the border of monitored region first death due to no more chance enter into sleep state, and then the death spread to the central region. This phenomenon is called as inequality sleep problems. To address this problem, we propose a method to determine some boundary nodes only using the minimum cost of nodes and the neighbors’ distance without any location information. We develop a location-Unaware nodes-scheduling schemes based on these determined boundary nodes called as LUNSB. Simulation results demonstrate that B-LUNS not only alleviates the inequality sleep problems, but also prolongs network lifetime.

PL

Jedną z najważniejszych metod ograniczenia energii sieci czujnikowej jest odpowiedni schemat szeregowania węzłów sieci. W tradycyjnych metodach szeregowania węzły na granicy monitorowanego obszaru uszkadzane są jako pierwsze, ponieważ mają małe szanse na wejście w stan spoczynku. Aby rozwiązać ten problem zaproponowano określenie kilku węzłów granicznych przyjmując, jako kryteria, tylko minimalny koszt oraz odległość do sąsiednich węzłów, bez uwzględnienia lokalizacji. Opracowano schematy szeregowania węzłów o nieznanej lokalizacji LUNSB w oparciu o granice zdefiniowane powyżej. Wyniki symulacji wykazują, że B-LUNS nie tylko łagodzą problem nierównego stanu spoczynku ale i przedłużają czas życia sieci.

5

Marginal Discriminant Projection for Coal Mine Safety Data Dimensionality Reduction

Zhao Z., Qian J., Cheng J.

Przegląd Elektrotechniczny

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2012

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R. 88, nr 9b

79-83

EN

Marginal Fisher Analysis (MFA) is a novel dimensionality reduction algorithm. However, the two nearest neighborhood parameters are difficult to select when constructing graphs. In this paper, we propose a nonparametric method called Marginal Discriminant Projection (MDP) which can solves the problem of parameters selection in MFA. Experiment on several benchmark datasets demonstrated the effectiveness of our proposed method, and appreciate performance was achieved when applying on coal mine safety data dimensionality reduction.

PL

W artykule zaproponowano nieparametryczna metodę nazwaną MDOP (marginal discriminant projection) która pomaga rozwiązać problem selekcji danych w algorytmie MFA (marginal Fisher analysis). Metodę zastosowano do redukcji danych w systemach bezpieczeństwa klopalni węglowych.

6

Sharp transition of laser-induced periodic ripple structures

Yang H., He H., Zhou L., Qian J., Hao J., Zhu H.

Optica Applicata

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2012

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Vol. 42, nr 4

795--803

EN

Laser-induced periodic surface structures (LIPSS) (ripple) with different spatial frequencies have been observed after irradiation of stainless steel surfaces by femtosecond laser pulses in the air. Low spatial frequency LIPSS (LSFL) with the period (about 830 nm) close to the laser wavelength and high spatial frequency LIPSS (HSFL) with half wavelength (about 410 nm) were dependent on the scanning speed of laser focus. The sharp transition from the single LSFL to double HSFL structures occurs at 5 mm/s. This abrupt transition of dividing one ripple into two equals was proved.

7

Diamond/SiC composites sintered under high-pressure-high temerature conditions

Żerda T. W., Qian J., Voronin G.

Karbo

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2003

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Nr 4

183-187

EN

Novel bulk diamond composites with nano size grain and nanocrystalline SiC bonding were sintered under high-pressure, high-temperature condi- tions. Nanostructured SiC matrix resulted in improved fracture toughness of the composites. Samples were prepared by high-energy ball milling and thorough powder mixing. Particular attention was paid to the diamond graphitization process, phase composition and stress-strain of the compo- sites. This study showed that pressure-temperature conditions in the diamond stable region are essential to avoid diamond graphitization and to sinter diamond/SiC composites with high hardness and strength. The graphitization rate depends on temperature, applied pressure, grain size, and population of surface defects.

PL

Opisano nowoczesne kompozyty na bazie sproszkowanego diamentu i na-nokrystalicznego węglika krzemu jako lepiszcza, które spiekano w warunkach wysokich ciśnień i temperatur. Użycie wypełniaczy z SiC zwiększyło w efekcie odporność takich kompozytów na kruszenie. Poszczególne sub-straty reakcji zmielono w młynku kulowym, dzięki czemu proszki uległy gruntownemu wymieszaniu. Szczególną uwagę poświęcono analizie procesu grafityzacji diamentu oraz składowi fazowemu i naprężeniom występującym w kompozytach. Badania wykazały, iż w celu uniknięcia grafityzacji diamentu oraz otrzymania kompozytów diament/SiC o wysokiej twardości i wytrzymałości, niezbędne jest prowadzenie całego procesu w obszarze stabilności fazowej diamentu. Szybkość grafityzacji zależy od temperatury, przyłożonego ciśnienia, wielkości ziaren oraz koncentracji defektów powierzchniowych.