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Bian Y.S.,Beihang University | Li K.K.,Beihang University | Shan B.,Machinery Technology Development Co.
Applied Mechanics and Materials | Year: 2014

An idea is proposed to use the controllable local degree of freedom to reduce vibration of the flexible manipulator performing the periodic task. The controllable local degree of freedom is incorporated into the flexible manipulator and used as an effective way to alleviate vibration through dynamic coupling. The feature of the periodic motion is utilized and a simple method is suggested to control vibration by constructing the appropriate modal control force via the controllable local degree of freedom, thereby counteracting the effects of the periodic exciting force. The numerical and experimental results preliminarily prove its effectiveness and feasibility in practical applications. © (2014) Trans Tech Publications, Switzerland.


Gao Z.H.,Beihang University | Liu B.D.,Beihang University | Shan B.,Machinery Technology Development Co.
Applied Mechanics and Materials | Year: 2014

A vibration control method is proposed to suppress nonlinear large vibration of the flexible robotic arm undergoing rigid motion. The method takes advantage of modal interaction and is implemented based on internal resonance. To attenuate vibration of the flexible arm, another vibrating system, consisting of a rigid link, a flexible joint and a damper, is introduced as a vibration absorber. Perturbation technique is used to study the transient response of the nonlinear equations of motion. Numerical simulation results preliminarily verify that the proposed control strategy is able to effectively reduce vibration of the flexible robotic arm. © (2014) Trans Tech Publications, Switzerland.


Liao Z.,Tsinghua University | Fogel G.R.,Spine Pain Begone | Pu T.,Machinery Technology Development Co. | Gu H.,Shenzhen Second Hospital | Liu W.,Tsinghua University
Medical Science Monitor | Year: 2015

Background: The ideal surgical approach for cervical disk disease remains controversial, especially for multilevel cervical disease. The purpose of this study was to investigate the biomechanics of the cervical spine after 3-level hybrid surgery compared with 3-level anterior cervical discectomy and fusion (ACDF). Material/Methods: Eighteen human cadaveric spines (C2-T1) were evaluated under displacement-input protocol. After intact testing, a simulated hybrid construct or fusion construct was created between C3 to C6 and tested in the following 3 conditions: 3-level disc plate disc (3DPD), 3-level plate disc plate (3PDP), and 3-level plate (3P). Results: Compared to intact, almost 65~80% of motion was successfully restricted at C3-C6 fusion levels (p<0.05). 3DPD construct resulted in slight increase at the 3 instrumented levels (p>0.05). 3PDP construct resulted in significant decrease of ROM at C3-C6 levels less than 3P (p<0.05). Both 3DPD and 3PDP caused significant reduction of ROM at the arthrodesis level and produced motion increase at the arthroplasty level. For adjacent levels, 3P resulted in markedly increased contribution of both upper and lower adjacent levels (p<0.05). Significant motion increases lower than 3P were only noted at partly adjacent levels in some conditions for 3DPD and 3PDP (p<0.05). Conclusions: ACDF eliminated motion within the construct and greatly increased adjacent motion. Artificial cervical disc replacement normalized motion of its segment and adjacent segments. While hybrid conditions failed to restore normal motion within the construct, they significantly normalized motion in adjacent segments compared with the 3-level ACDF condition. The artificial disc in 3-level constructs has biomechanical advantages compared to fusion in normalizing motion. © Med Sci Monit, 2015.


Liao Z.,Tsinghua University | Pu T.,Machinery technology development CO LTD | Gu H.,Shenzhen Second Hospital | Liu W.,Tsinghua University
Bio-medical materials and engineering | Year: 2015

To compare the biomechanical characters of three-level anterior cervical fusion and hybrid constructs by measuring coupled motion changes of the cervical spine, Eighteen adult human cadaveric cervical spines were biomechanically investigated under eccentric displacement control in lateral bending and axial rotation by measuring vertebral motion (X, Y, Z -axis).The 3DPD condition displayed similar coupled motion compared to the intact condition both in lateral bending and in axial rotation, while the 3PDP condition was similar only in lateral bending. However, the coupled motion of the cervical spine under 3P conditions markedly changed in both lateral bending and axial rotation. Considering the coupled motion characteristics, the 3DPD hybrid construct is biomechanically advantageous in three types of reconstructions (3DPD, 3PDP, 3P).


PubMed | Tsinghua University, Shenzhen Second Hospital and Machinery technology development CO LTD
Type: | Journal: Bio-medical materials and engineering | Year: 2015

To compare the biomechanical characters of three-level anterior cervical fusion and hybrid constructs by measuring coupled motion changes of the cervical spine, Eighteen adult human cadaveric cervical spines were biomechanically investigated under eccentric displacement control in lateral bending and axial rotation by measuring vertebral motion (X, Y, Z -axis).The 3DPD condition displayed similar coupled motion compared to the intact condition both in lateral bending and in axial rotation, while the 3PDP condition was similar only in lateral bending. However, the coupled motion of the cervical spine under 3P conditions markedly changed in both lateral bending and axial rotation. Considering the coupled motion characteristics, the 3DPD hybrid construct is biomechanically advantageous in three types of reconstructions (3DPD, 3PDP, 3P).


PubMed | Tsinghua University, Machinery technology development Co., Spine Pain Begone and Shenzhen Second Hospital
Type: | Journal: Medical science monitor : international medical journal of experimental and clinical research | Year: 2015

The ideal surgical approach for cervical disk disease remains controversial, especially for multilevel cervical disease. The purpose of this study was to investigate the biomechanics of the cervical spine after 3-level hybrid surgery compared with 3-level anterior cervical discectomy and fusion (ACDF).Eighteen human cadaveric spines (C2-T1) were evaluated under displacement-input protocol. After intact testing, a simulated hybrid construct or fusion construct was created between C3 to C6 and tested in the following 3 conditions: 3-level disc plate disc (3DPD), 3-level plate disc plate (3PDP), and 3-level plate (3P).Compared to intact, almost 65~80% of motion was successfully restricted at C3-C6 fusion levels (p<0.05). 3DPD construct resulted in slight increase at the 3 instrumented levels (p>0.05). 3PDP construct resulted in significant decrease of ROM at C3-C6 levels less than 3P (p<0.05). Both 3DPD and 3PDP caused significant reduction of ROM at the arthrodesis level and produced motion increase at the arthroplasty level. For adjacent levels, 3P resulted in markedly increased contribution of both upper and lower adjacent levels (p<0.05). Significant motion increases lower than 3P were only noted at partly adjacent levels in some conditions for 3DPD and 3PDP (p<0.05).ACDF eliminated motion within the construct and greatly increased adjacent motion. Artificial cervical disc replacement normalized motion of its segment and adjacent segments. While hybrid conditions failed to restore normal motion within the construct, they significantly normalized motion in adjacent segments compared with the 3-level ACDF condition. The artificial disc in 3-level constructs has biomechanical advantages compared to fusion in normalizing motion.


Peng Y.,Beijing University of Technology | Peng Y.,Harbin Institute of Technology | Yang A.,Beijing University of Technology | Li L.,Machinery Technology Development Co. | Wu L.,Beijing University of Technology
Harbin Gongye Daxue Xuebao/Journal of Harbin Institute of Technology | Year: 2013

Domestic wastewater was treated by using three parallel sequencing batch reactors (SBR) at the pH of 7.9-8.0 to optimize aeration duration of partial nitrification. The partial nitrification was achieved and maintained by controlling the aeration time of t/2, t/4, t/8 respectively (t was aeration time) before appearance of "ammonia valley". Nitrite accumulation ratios were improved by 50%, 65%, 90% respectively in the three reactors which were operated in 145 days. FISH quantitative analysis showed that the percentage of ammonia oxidizing bacteria (AOB) in the reactors increased differently. AOB and nitrite oxidizing bacteria (NOB) was 3.89% and 0.27% of the total bacteria respectively in No.3 reactor, which showed that AOB is the dominant bacteria in nitrifying bacteria. It is concluded that synergistic effect between the optimal control of aeration duration and the inhibition of FA would be the key factors to rapid start-up and maintain the stable nitrification.


Zhao W.B.,Hefei University of Technology | Ju Y.K.,China University of Geosciences | Peng W.,Machinery Technology Development Co.
Advanced Materials Research | Year: 2014

Fly ash and sludge are all solid waste. With fly ash as an additive, sludge is composted in aerobic condition, which can achieve agricultural requirements. After testing, we find that the activity of fly ash can be promoted and stimulated by adding different proportions of activator under alkaline conditions, which has a low activity under conventional conditions. Adding slow-releasing additive, fertility of sludge may keep longer, which has a certain reference value to agricultural fertilizer production. © (2014) Trans Tech Publications, Switzerland.


Chen D.,China Academy of Machinery Science and Technology | Chu Z.,China Academy of Machinery Science and Technology | Zheng H.,China Academy of Machinery Science and Technology | Zheng H.,Machinery Technology Development Co. | Wang X.,China Academy of Machinery Science and Technology
Tezhong Zhuzao Ji Youse Hejin/Special Casting and Nonferrous Alloys | Year: 2012

Basing on die casting mold optimal selection, structure design and die offer of the authority knowledge and expert experience, we estabished die-casting die material knowledge base, design knowledge base and offer knowledge base. Human-machine interface was designed which mainly included material selection module, design module, offer module and knowledge module. Casting die material selection and auxiliary design expert system was eventually developed through the man-machine interface and knowledge base connection.


He A.,University of Science and Technology Beijing | Liu D.,Machinery Technology Development Co. | Liu C.,University of Science and Technology Beijing
Jixie Gongcheng Xuebao/Journal of Mechanical Engineering | Year: 2016

The continuously elastic-plastic mechanical behavior of the plastic hardening material is analyzed by the elastic-plastic bending theory and stress linear superposition principle, and a continuous elastic-plastic bending-straightening processing mechanical model of the leveler with seven rollers is established considering the effect of stress transfer effect on straightening process. By comparing the experimental results and theoretical calculations, the average deviation is less than 8%, which verify the theoretical analysis is correct. Using this model, different straightening strategies are analyzed. The results show that the large deformation straightening strategy is better than the small deformation straightening strategy in the controlling ability of the residual stress and residual curvature. Because of stress transfer effect on straightening process, the residual curvature does not converge to zero but fluctuate within a certain range with the straightening processing by the small deformation straightening strategy; The large deformation straightening strategy adopts gradual straightening process setting method, so it can achieve the purpose of straightening. All these results provide a theoretical basis for straightening strategy selection in industrial production. © 2016 Journal of Mechanical Engineering.

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