A new interpretation of commutation failure risk, considering the circuit topology when commutation, is presented in this paper. The basic idea is to compare the difference of commutation angle of the relevant inverte...
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ISBN:
(纸本)9781538614280
A new interpretation of commutation failure risk, considering the circuit topology when commutation, is presented in this paper. The basic idea is to compare the difference of commutation angle of the relevant inverter after a new HVDC system is constructed. The equivalent circuit is indicated to deduce and derive the commutation angle. Then analysis on the impact factor of commutation angle is carried out. As a result, the equivalent commutation impedance of the relevant inverter is proved to increase, and so is the commutation angle. Hence the risks of commutation failure are enlarged. Validated by case studies in PSCAD/EMTDC, the presented interpretation is confirmed.
Objective To investigate the effect of fibre periodontal splint restoration on mandibular anterior teeth displacement and periodontal membrane stress. Methods Micro-CT scanning technology, combined with Mimics, Geomag...
Objective To investigate the effect of fibre periodontal splint restoration on mandibular anterior teeth displacement and periodontal membrane stress. Methods Micro-CT scanning technology, combined with Mimics, Geomagic studio and SolidWorks were used to establish 3D dental models of mandibles with teeth and the models fibre periodontal splint restoration; the models of mandibular anterior loosen teeth was constructed under 30 degree oblique 25N loading on the labial and lingual sides respectively. Then, under different angles force with or without the splint, the analysis on dental mechanical state are given. Results It was determined that the sum of the maximal displacement of the loosen tooth model at the lingual and labial sides was 1 mm, which represented the degree I loosen model. After splint repair on the model, the maximal displacement of loosen tooth decreased 47.7%, 85.1% and 85.8% at 0 degree, 15 degree and 30 degree forces respectively, and the maximum stress of periodontal membrane decreased by 22.3%, 61.2% and 74.9%. Conclusion Fixation of loosen teeth through fibre periodontal splints can reduce the maximum stress of periodontal membrane and the maximal displacement of the teeth, thus ensuring the stability of loosen tooth.
In this paper,a novel steamer feeding robot is designed and *** compared to the currently used steamer feeding robot,the feeding process of the proposed robot is continuous,and this way will greatly improve the effici...
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ISBN:
(纸本)9781138065833
In this paper,a novel steamer feeding robot is designed and *** compared to the currently used steamer feeding robot,the feeding process of the proposed robot is continuous,and this way will greatly improve the efficiency and quality of the feeding ***,the mechanical structure and kinematics of the novel steamer feeding robot are introduced and *** then,the control system of the robot is ***,experiment evidences are given to prove the efficiently of brewing by using this robot.
The identification model of milling force coefficient is established using the model of dynamic milling force and the regression analysis of the milling force experiment data. On the basis of the existing milling forc...
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The identification model of milling force coefficient is established using the model of dynamic milling force and the regression analysis of the milling force experiment data. On the basis of the existing milling force model, by simplifying and calculation, it can get the relational expression between milling force coefficient and average value of the milling force. Arranging the milling force experiment and measuring average milling force, the experiment results of milling force coefficient can be calculated. Then, the polynomial expression of identification model of milling force coefficient is established, and its coefficient values can be got by regression analysis. Finally, the accuracy and applicability of the identification model is verified by experiment. The experimental results show that the prediction results of the model are accurate and reliable, and can meet different processing conditions, provide the theoretical basis and reference for the further study of milling process and optimization.
P91 heat-resistant steel is widely used in the high temperature of piping components of thermal power plants and nuclear power plants. In these conditions, the typical failure of P91 is mainly caused by creep at low s...
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Reconfigurability of the modular robot is becoming curial to be a high flexibility for the wide varieties of tasks and environments. In this paper, a novel self-reconfigurable modular robot called M 2 sbot is designed...
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ISBN:
(纸本)9781509023974
Reconfigurability of the modular robot is becoming curial to be a high flexibility for the wide varieties of tasks and environments. In this paper, a novel self-reconfigurable modular robot called M 2 sbot is designed, which has the approximate cuboid shaping structure. The unit model is with one active and five passive connection surfaces, compact structure and flexible motion. It is characterized by using the unique hook-claw docking mechanism as the docking part of the neighbor modular. And the responding control system based on STM32F103VET6 is also implemented. The forward kinematic equations of the chain robot are established, and then the dynamic equation is generated by the recursive Newton-Euler method based on the global matrix description. Finally, the calculation and simulation analysis of the six-module configuration with two branches demonstrates the feasibility of the proposed method in the generation of motion equation.
This paper presents a new type of multifunctional bioreactor, which is to provide cell tissue a mechanical environment which is close to the real situation. This bioreactor is based on the concept of fatigue machine, ...
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This paper presents a new type of multifunctional bioreactor, which is to provide cell tissue a mechanical environment which is close to the real situation. This bioreactor is based on the concept of fatigue machine, add torsion module to compress and tension module, with new design of both loading device and culturing device by modern CAD technology. Driven by voice coil motor, step motor and a well designed mechanical structure, this machine has excellent controlling performance and no accumulated error, easy to adjust operating height, loading frequency, compressing stroke and torsioning angle. It has different loading modes, with compression or torsion separately, or providing compound load with both torsion and compression. With a delicate culturing device, the height and the limit of loading head is easy to adjust accordingly, it can also provide liquid environment during the loading process, which is closer to biological characteristics and physiological environment. After simple refit, it's also able to be used as a tension machine. This machine supplies different mechanical environment for biomechanics research to make related experiments more effective and accurate.
The experiments of turning titanium alloy are carried out by using central composite design, the influences of cutting speed, feed rate and cutting depth on surface roughness are analyzed. The surface roughness predic...
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ISBN:
(纸本)9781509023974
The experiments of turning titanium alloy are carried out by using central composite design, the influences of cutting speed, feed rate and cutting depth on surface roughness are analyzed. The surface roughness prediction model is established based on the response surface method. The significance of the regression equation is validated and the influences of the cutting parameters on surface roughness are compared. The results show that: within the range of cutting parameters used in the experiments, the most significant parameter on surface roughness is given by feed rate, followed by cutting depth, and the cutting speed has minimal effect on surface roughness;the prediction model is significant. It can be used to select various suitable parameters before the machining processing to predict and control the surface roughness.
Studies have shown that the morphology and function of living cells are greatly affected by the state of different high acceleration. Based on the centrifuge, we designed a centrifugal cell loading machine for the mec...
Studies have shown that the morphology and function of living cells are greatly affected by the state of different high acceleration. Based on the centrifuge, we designed a centrifugal cell loading machine for the mechanical biology of cells under high acceleration loading. For the machine, the feasibility of the experiment was studied by means of constant acceleration or variable acceleration loading in the Petri dish fixture and/or culture flask. Here we analyzed the distribution of the acceleration of the cells with the change of position and size of the culturing device quantitatively. It is obtained that Petri dish fixture and/or culture flask can be used for constant acceleration loading by experiments; the centripetal acceleration of the adherent cells increases with the increase of the distance between the rotor center of the centrifuge and the fixture of the Petri dish and the size of the fixture. It achieves the idea that the general biology laboratory can conduct the study of mechanical biology at high acceleration. It also provides a basis for more accurate study of the law of high acceleration on mechanobiology of cells.
A comparative study of two over-constrained 2-RPU+SPR parallel manipulators (PM) is studied in terms of workspace and transmission performance in this paper. The two 2-RPU+SPR PMs have identical kinematics limbs, but ...
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ISBN:
(纸本)9781467384155
A comparative study of two over-constrained 2-RPU+SPR parallel manipulators (PM) is studied in terms of workspace and transmission performance in this paper. The two 2-RPU+SPR PMs have identical kinematics limbs, but some differences exist in terms of the joints distribution. The kinematics, the workspace and the transmission performance are studied and simulation examples are presented to demonstrate the differences between the two PMs. This study provides insights into the two parallel manipulators with identical limbs but with different joints distribution.
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