Beijing Institute of Machinery

Beijing, China

Beijing Institute of Machinery

Beijing, China

Beijing Institute of Machinery is a university in Beijing, China.One of the two universities that merged into Beijing Information Science & Technology University. Now, although the title of Beijing Institute of Machinery is no longer officially used, the school is considered half of the newly founded institution, Beijing Information Science & Technology University. The university takes engineering as its main faculty combined with management, liberal and science programs. See more: http:/ Wikipedia.

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Li N.,Harbin Engineering University | Liu H.,Beijing Institute of Machinery | Su Y.,Harbin Engineering University
PLoS ONE | Year: 2017

Numerical simulations are employed to study the hydrodynamics of self-propelled thunniform swimming. The swimmer is modeled as a tuna-like flexible body undulating with kinematics of thunniform type. The wake evolution follows the vortex structures arranged nearly vertical to the forward direction, vortex dipole formation resulting in the propulsion motion, and finally a reverse Kármán vortex street. We also carry out a systematic parametric study of various aspects of the fluid dynamics behind the freely swimming behavior, including the swimming speed, hydrodynamic forces, power requirement and wake vortices. The present results show that the fin thrust as well as swimming velocity is an increasing function of both tail undulating amplitude Ap and oscillating amplitude of the caudal fin θm. Whereas change on the propulsive performance with Ap is associated with the strength of wake vortices and the area of suction region on the fin, the swimming performance improves with θm due to the favorable tilting of the fin that make the pressure difference force more oriented toward the thrust direction. Moreover, the energy loss in the transverse direction and the power requirement increase with Ap but decrease with θm, and this indicates that for achieving a desired swimming speed increasing θm seems more efficiently than increasing Ap. Furthermore, we have compared the current simulations with the published experimental studies on undulatory swimming. Comparisons show that our work tackles the flow regime of natural thunniform swimmers and follows the principal scaling law of undulatory locomotion reported. Finally, this study enables a detailed quantitative analysis, which is difficult to obtain by experiments, of the force production of the thunniform mode as well as its connection to the self-propelled swimming kinematics and vortex wake structure. The current findings help provide insights into the swimming performance and mechanisms of self-propelled thunniform locomotion. © 2017 Li et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Zong C.,University of Aarhus | Zhang G.,University of Aarhus | Feng Y.,University of Aarhus | Feng Y.,Beijing Institute of Machinery | Ni J.-Q.,Purdue University
Biosystems Engineering | Year: 2014

Carbon dioxide (CO2) is useful for determining ventilation rates in livestock buildings and its release from manure plays an important role in ammonia emission. CO2 production in a fattening pig house with a partial pit ventilation system was investigated under working conditions. The influences of animal mass, animal activity, and ventilation rate on CO2 concentrations and emissions were assessed. Results showed that the CO2 production rate increased with growing pig body mass. A mathematical model of CO2 production was developed based on the measured data. The measured CO2 productions ranged from 30.3 to 99.0gh-1pig-1 for pigs from 30.1 to 111.5kg. Comparing the last days of the fattening period with and without pigs, it was found that 2.3-3.4% of the total CO2 production was released from manure. Higher pit ventilation rates resulted in higher CO2 concentration in pit air and higher emission rates via pit exhaust, but had limited influence on the total emission rate (via room+pit exhaust). However, higher room ventilation rates resulted in lower CO2 concentrations in room air but higher room and total emission rates. Diurnal variations in CO2 productions were mainly influenced by animal activities. Four models of CO2 production in literature were reviewed and compared with the model developed in this study. The CO2 production model developed in this study had similar values with the CIGR model for a pig under 80kg and the TCER model for a pig above 60kg. © 2014 IAgrE.

Zong C.,University of Aarhus | Feng Y.,University of Aarhus | Feng Y.,Beijing Institute of Machinery | Zhang G.,University of Aarhus | Hansen M.J.,University of Aarhus
Biosystems Engineering | Year: 2014

It has previous been demonstrated that a pit ventilation system could improve indoor air quality and reduce ammonia emission significantly from pig production if an air purification system was installed to treat the pit exhaust air. However, the knowledge about the influence of a partial pit exhaust unit treating a small part of the ventilation (10%) in a ventilation system with different types of air inlets on indoor air quality and ammonia emission from pig house is still lacking. In this study, two rooms, both with partial pit exhaust and ceiling-top room exhaust units, were used. One room was equipped with ceiling air inlet (system C) and another room was equipped with wall jet air inlet (system W). Each room had 32 fattening pigs. The maximum ventilation rate in each room was set as 3200m3h-1. Room ventilation rate was automatically controlled by a climate control strategy based on indoor thermal conditions, while pit ventilation rate was fixed at 10% of the maximum ventilation rate. Ammonia concentrations were measured in air inlet, room exhaust and pit exhaust for both systems. Air flow rates and ammonia concentrations were measured and recorded continuously. Results showed that ventilation rate requirement was higher in system C than in system W (22.3%, p<0.001) to maintain the setup indoor thermal condition during the whole fattening period. In the meantime, significant higher ammonia concentrations and emissions in both pit and room exhausts were found in system W than in system C (p<0.001). The ammonia emission ratio of pit exhaust, defined as the emission via pit exhaust divided by the total emission, in systems C and W was 48% and 47%, respectively. If applying an effective air purification system, a significant reduction of ammonia emission could be achieved. The gap of ammonia concentration difference between system C and W increased in the later stage. Higher room ventilation rate led to smaller difference of ammonia concentration in room air. Slurry depth had a positive effect on the ammonia emission from pit exhaust. No significant difference in the pigs' activity was found between the two ventilation systems. © 2014 IAgrE.

Zhu Z.,Beijing Institute of Machinery | Xu D.,Beihang University | Liu J.,Beihang University | Xia Y.,Beijing Institute of Technology
IEEE Transactions on Industrial Electronics | Year: 2013

The problem of missile interception is investigated in this paper. Sliding-mode controllers with finite-time convergence are proposed for the design of guidance laws. In particular, the control design consists of the estimation of the target acceleration by the extended state observer (ESO), and thus, it achieves the decrease of undesired chattering effectively. Also, simulation results are presented to illustrate the effectiveness of the control strategies. © 1982-2012 IEEE.

Yang M.,Harbin Institute of Technology | Yang M.,Beijing Institute of Machinery | He P.,Harbin Institute of Technology | Lin T.,Harbin Institute of Technology
Journal of Materials Science and Technology | Year: 2013

Al2O3 and Ti-6Al-4V alloy were brazed with Ag-Cu-Ti+B fillers in different brazing conditions. Effects of brazing temperature, holding time and additive Ti content on joints microstructure and shear strength were investigated by scanning electron microscopy, energy dispersive spectrometry, X-ray diffraction, transmission electron microscopy and shear testing. Results indicate that TiCu and Ti(Cu,Al) decrease, but Ti2Cu and Ti2(Cu,Al) increase in brazing seam with increasing brazing temperature, holding time and additive Ti content. Area consisting of Ti3(Cu,Al)3O and TiO near Al2O3 becomes gradually discontinuous from continuity when brazing temperature rises or holding time extends. As Ti additive content increases, TiO is absent near Al2O3; area consisting of only Ti3(Cu,Al)3O thickens. TiB whiskers are in situ synthesized by Ti and B atoms during brazing process. The brazing temperature, holding time and additive Ti content on joints microstructure influence the joints shear strength directly. The shear strength of joints, obtained at 850°C holding for 10min, reaches the maximum of 78MPa. According to the experimental results, phase diagram and thermodynamics calculation, the interface evolution mechanism of the Al2O3/Ti-6Al-4V alloy joint was analyzed. © 2013.

Liu X.,North China Electrical Power University | Guan P.,Beijing Institute of Machinery | Chan C.W.,University of Hong Kong
IEEE Transactions on Control Systems Technology | Year: 2010

A coordinated control strategy is often used to ensure a thermal power plant to have a higher rate of load change, but without violating the thermal constraints. Although model predictive control has been widely used for controlling power plant, handling input constraints is a major problem especially as these plants are nonlinear. Two alternative methods of exploiting the nonlinear predictive control are presented in this paper. One is the input-output feedback linearization technique based on a suitably chosen approximated linear model. The other is based on neuro-fuzzy networks to represent a nonlinear dynamic process using a set of local models. From the criteria based on the integral absolute errors and the relative optimization time for completing the simulation, it is shown that the performance of the coordinated control of a steam-boiler generation plant using these two nonlinear predictive methods are better than the conventional predictive method. © 2010 IEEE.

Liu Q.,Nanjing University of Aeronautics and Astronautics | Liu Q.,Anqing Teachers College | Zhao Z.,Nanjing University of Aeronautics and Astronautics | Li Y.-X.,Beijing Institute of Machinery | Li Y.,Nanjing University of Aeronautics and Astronautics
Neurocomputing | Year: 2012

A feature selection method based on sensitivity analysis and the fuzzy Interactive Self-Organizing Data Algorithm (ISODATA) is proposed for selecting features from high dimensional gene expression data sets. First, feature sensitivities for discriminating classes are calculated on the basis of the fuzzy ISODATA method. Then, candidate feature subsets are generated according to feature sensitivities with the recursive feature elimination procedure. Finally, the obtained optimal feature subsets are evaluated using both supervised and unsupervised methods to validate their abilities for separating different categories. The proposed method is applied to five microarray datasets, and the experimental results indicate its effectiveness. © 2012 Elsevier B.V..

Li D.-J.,Beijing Institute of Machinery | Gao X.,Beijing Institute of Machinery | Zhu S.-M.,Beijing Institute of Machinery
Tuijin Jishu/Journal of Propulsion Technology | Year: 2013

The 2D hypersonic curved shock compression inlet has a shorter length and higher performance. In order to investigate the ramp design method applying the curved shock compression between Ma=4 and Ma=7, the performance of the 2D hypersonic inlets with the curved shock compression and the isentropic compression have been investigated in comparison. 2D numerical simulation was conducted for the inlet according to the given law of constant wall pressure gradient so as to obtain flow characteristics. Numerical results show that compression efficiency is high. Based on the comparison for the total pressure recovery ratio and the length of the inlets with the different initial angles, the ramp initial angle can not exceed 7° and the length ratio of the inlet can be shortened about 10%. Compared with the curved shock inlet and the isentropic inlet, the total pressure recovery ratio of the curved shock inlet with law of constant wall pressure gradient drops about 3%~5%, but the design point of shock on lip can be dropped. In the end, three dimensional waveride forebody with good waveride performance and 2D flow characteristics was conducted with the streamline trace, and shock wave surface was obtained near the design point.

Chen L.P.,Beijing Institute of Machinery
Advanced Materials Research | Year: 2014

The achievement, which Chinese Equipment Manufacturing Industry had accomplished in the ten years after China accessed the World Trade Organization, is first analyzed through the production scale, the export trade, the industry structure and the comprehensive strength and so on in the paper. The problems, which exist in the products, the production capacity, the independent innovation capacity, the production means and the internal and external environment of Chinese Equipment Manufacturing Industry, are pointed out. Some suggestion on the future development strategy is last put forward. © (2014) Trans Tech Publications, Switzerland.

Teng H.,CAS Institute of Mechanics | Zhang Y.,Beijing Institute of Machinery | Jiang Z.,CAS Institute of Mechanics
Computers and Fluids | Year: 2014

Oblique detonation waves are simulated to study the induction zone structures with different incident Ma numbers. Three kinds of shock configurations are observed at the end of the induction zone, which are the λ-shaped shock, the X-shaped shock and the Y-shaped shock. The X-shaped and Y-shaped shocks appear when the incident Ma is low, and the Y-shaped shock associated with the complicated unstationary process. The induction zone length reaches the maximum value when the X-shaped shock changes into the Y-shaped shock, which indicates different mechanisms deciding the induction zone. The oblique shock wave dominates the induction zone when the incident Ma is high, while the oblique detonation wave dominates the induction zone when the incident Ma is low. © 2014 Elsevier Ltd.

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