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The bladed rotor is an important part in turbine machines. Timely detection of its blade rubbing fault may avoid serious accidents. This paper developed a rub-impact fault identification approach for the bladed rotor based on chaotic features such as average period, time delay, embedded dimension, and largest Lyapunov exponent. A dynamic analytical model of a rotating variable thickness blade with the rub-impact fault is established. It is verified that the blade rubbing model could obtain the relationship between the chaotic behaviors and the rub-impact fault for a rotating blade. Through the nonlinear characteristic analysis, we could establish that different blade rubbing states have a certain corresponding relationship with the chaotic characteristics, which provides the theoretical basis for the blade rubbing identification using the chaotic features. In particular, a rub-impact fault identification approach based on chaotic features is further studied. And the blade rubbing fault can be easily identified by combining four chaotic features, which is proven by experiments. Comparing with the time domain and frequency domain analysis methods, the proposed approach provides a new way to identify such blade rubbing fault.

Developing techniques for removing lead from its aqueous solution is an important subject with great application prospect. In this article, it was found that by using very small amount of selenium dopant (0.34 w/w%), the carbon-based selenium materials (Se/C) could adsorb over 2.56 times more Pb than simple carbon for the Se-metal coordination features. The material was very practical and could be successfully employed in the treatment of industrial wastewater from a lead battery factory with a variety of impurities. It has been successfully applied as the key working material in our wastewater treatment equipment. The used Se/C containing heavy metals could be treated by the combustion method to give the solid wastes with very little weight for transport and storage (ca 0.18% of the wastewater weight), which were then sent to the solid waste treatment plant to recycle the metal resources. Since Se/C can be fabricated by using cheap, abundant and renewable carbohydrates as the carbon source, the cost of the material is relatively low, affording a practical material for lead waste treatment.

With the continuous improvement of the performance of intelligent devices, the continuous improvement of HTML5 and related technologies, and the rapid de velopment of mobile social applications such as wechat and Sina. A variety of innovative, well-made mobile HTML5 advertising has entered the public eye. HTML5 advertising on the mobile terminal combines the characteristics of mobile intelligent devices, and brings the audience audio-visual enjoyment, emotional and spiritual interactive experience. Autonomous learning has been attached great importance to college teaching. With the continuous improvement of the level of science and technology, network teaching has gradually penetrated into the actual teaching environment of colleges and universities. The teaching contents of network teaching courses and open courses in Colleges and universities fully reflect the important value of network teaching. Artificial intelligence technology will have a broad and far-reaching impact on the education system, and promote the overall reform of the teaching system. This paper analyzes the influence of artificial intelligence technology on education, and then clarifies the elements of teaching system and the relationship between learning methods and learning resources in the era of artificial intelligence.

In this study, the evolution trends in various hydrogen storage properties as well as kinetics performance of LaNi5−xCox (x = 0, 0.25, 0.50 and 0.75) alloys up to 1000 cycles are studied, and the effects of Co on the long-term hydrogen absorption/desorption properties are revealed. The alloys have single LaNi5 phase structure. The cell volume increases with increasing Co content, resulting in a lower hydrogen absorption/desorption plateau pressure and a more stable hydride phase. The alloys have good kinetics performance and can fully absorb hydrogen within 300 s. The hydrogen absorption rate increases with either cycling or Co addition, but neither of them changes the rate limiting step which remains to be diffusion controlled model in the temperature range of 343–383 K. With cycling, an intermediate γ phase emerges with the coexistence of α and β phases indicated by an extra higher plateau in P-C-T curves. This γ phase acts as a buffer releasing the microstrains which is reflected from the slower capacity degradation, and the significant decrease in hysteresis and slope factor upon its appearance. Moreover, the c/a value increases after 1000 cycles which also relieves the microstrains in the alloys. Co addition not only enhances the buffer effect of γ phase by partially combining it with β phase, but also promotes the increasing degree of c/a value, contributing to a better crystal structure, bigger particle size and higher cycle stability during long-term cycling.

The long-term hydrogen storage performance of a CaCu5-type LaNi4Co alloy is studied by detailed analysis of its P-C-T curves and structural changes within 1000 cycles. The alloy shows one absorption plateau (α→β phase transition) and two desorption plateaus (γ→β and β→α phase transitions). With increasing cycle number, the plateau pressures for both α→β and β→α phase transitions decrease due to the increase in cell volumes. The increased crystal cells also provide more space to accommodate the simultaneous occupations of 12° and 6 m sites, and thus β→α and β→γ desorption plateaus become less distinguishable. During cycling, partial phase decomposition, crystal grain destruction and surface oxidation occur, resulting in the loss of hydrogen storage capacity. In addition, due to the increase in the atomic disorder and internal microstrains and defects, the average slope factors (SF/H%) of the hydrogen absorption/desorption plateaus are increased. Particularly, the SF/H% value of the γ→β plateau is always higher than those of the α→β and β→α plateaus, and it also increases faster with cycling, reaching about 4 times of the other two plateaus at the 1000th cycle. It is considered that the improvement of the γ→β phase transition process is significant to promote the cycling behavior and practical applications of this alloy system.

In this work, various amounts of (La,Mg)5Ni19 phase is successfully produced in a A2B7-type La0.75Mg0.25Ni3.5 alloy by zone heating the as-cast alloy at the peritectic reaction temperature of the (La,Mg)5Ni19 phase (1203 K) for different durations. The formation process, electrochemical effects and functioning mechanism of the (La,Mg)5Ni19 phase are studied. The as-cast alloy contains (La,Mg)2Ni7 and LaNi5 main phases, and (La,Mg)5Ni19 minor phase. During zone heating, the peritectic reaction between the LaNi5 solid phase and the melted (La,Mg)2Ni7 liquid phase occurs, forming (La,Mg)5Ni19 phase. Thus the (La,Mg)5Ni19 phase abundance increases from 9.8 wt% (as-cast) to 46.2 wt% (heated for 24 h). The hydrogen desorption plateau pressure of the alloys increases with increasing (La,Mg)5Ni19 phase abundance, contributing to fast hydrogen desorption and large current dischargeability. In addition, the (La,Mg)5Ni19 phase network in the alloy matrix has a good structural stability against repeated hydrogen absorption/desorption, keeping the alloy from serious lattice destruction and crystal defects. Moreover, the discrete expansion/contraction between the LaNi5 phase and the superlattice phases during cycling decreases with the consumption of the LaNi5 phase, which relives the alloys' pulverization, and thus enhancing the oxidation resistance. Thereby, the cycling stability of the alloy electrodes of the 150th cycle increases from 65.4% (9.8 wt% (La,Mg)5Ni19 phase) to 80.4% (46.2 wt% (La,Mg)5Ni19 phase).

Outer ring of bearing fit looseness fault is a common fault. Scratch often appears in the inner surface of pedestal. The fit looseness fault mechanism is not clear. For rotor-rolling bearing system with fit looseness fault between rotor-bearing outer ring and pedestal, a rotor coupling dynamic model that the interaction of bearing outer ring and pedestal are considered. This model is different from the universal rubbing model, where the directions of relative motion between rotor and stator are not considered. Numerical integration method is used to obtain the response of the system where the rotor is established by FEM and the bearing outer ring and pedestal are established by lumped mass model. Firstly, modal test results and simulation results were used to verify the correctness of this model. Secondly, the role of tightening torque between bearing outer ring and pedestal is considered, and the response characteristics of bearing and rotor are analyzed when fit looseness fault is considered. Finally, comparing the simulation results with test results, the waveform and spectrum are similar, which verifies the correctness of the fit looseness model. The fit looseness fault characteristics are that the acceleration after noise reduction shows periodic impact, up and down asymmetry, multiple frequencies appear. A method by increasing tightening torque is put forward to control the vibration caused by fit looseness fault.

In turbo-machinery, wide-chord blades are widely used due to the advantages of improving fan efficiency and aerodynamic performance. The rotor with multiple wide-chord blades is spaced from the outer casing. The small clearance may cause rub-impact fault between wide-chord blades and the casing, which induces different damage severity or the destruction of the whole machine. Numerical simulation is necessary to analyze this kind of rub-impact fault, but the solution process becomes complicated because of the coupling of geometric nonlinearity, local vibrations of wide-chord blades and gyroscopic motion of the rotor. This paper develops a rubbing rotor model with multiple wide-chord blades considering the gyroscopic effect and geometric nonlinearity induced by rub-impact. Based on the rub-impact model established for wide-chord blades, the high-order nonlinear governing equations of the bladed rotor are derived. Vibration responses are solved, and a series of dynamic characteristic analysis is carried out. The results reveal that high-order nonlinearity has a little effort on vibrations during slight rub-impact. But with the increase of transverse deformation induced by severe tip-rub, its influence cannot be ignored. Besides, localized rub-impact phenomenon of blades induced by external synchronous forces is found. Instead, external asynchronous force makes all blades rub, one after another along the circumferential direction of the disk, and there is a phase difference Δ φ = 2 π / Ω ± ω N b between the vibration responses of adjacent blades. Then, we found that the swing motion intensifies the difference of transverse deformations along the chord direction of wide-chord blades with tip-rub, which may induce the edge failures. Also, the swing motion intensifies the steady rub-impact fault. It could weaken or eliminate its divergence and instability when the rotor with multiple wide-chord blades is unstable. The gyroscopic effect could weaken the swing motion, and then weakens the stable rub-impact fault.

High speed motor with magnetic bearings has been developing due to its advantages of small size, high power density, no mechanical wear and low maintenance cost. In order to reduce vibrations, dynamic characteristics of the flexible rotor system of high speed motor for operation rotation speed 200000r/min with magnetic bearings are investigated. Results show that high speed motor may pass through some critical speeds and it is accurate to consider the motor shaft as a flexible rotor. Meanwhile, it is necessary to take measures to reduce the amplitude of resonance region of high speed motor such as increasing system damping. The critical speed increases with the increase of the bearing stiffness, which is a good way to remove the critical speed below working rotation speed.

In a hypersonic wind tunnel, the motion of the electric putter Y mechanism needs to be controlled synchronously, and the accuracy or control performance of the system's synchronous motion control directly affects the running quality of the wind tunnel. Based on the deviation coupling mechanism of output displacement, the paper puts forward the synchronous control system of the model mechanism electric putter Y mechanism, and establishes the dynamic model of the mechanical system, current control ring, speed control ring and position control ring of the electric putter Y mechanism. A closed-loop synchronous three-ring control system is designed, and performance simulation is carried out. The results show that the system has fast synchronous response speed, high accuracy of synchronous displacement and synchronous speed control, and the system has strong robustness.

In some products or systems, the redundant parts, components or subsystems must be configured for their high reliability, in addition to the high reliability of parts and components. But the systems would pay more "cost" of resources such as cost, weight or volume, than those without redundancy of parts, components and subsystems. Therefore, the study of redundant reliability optimization for the system would be carried out. This paper presents several models for basic component structures of reliability based on the block diagram. According to the block diagram model for series-parallel reliability of components and subsystems, a mathematical model and its optimization method for system redundant reliability optimization are established, which are based on dynamic programming. Then the ball screw actuator system was taken as an example, and the redundant reliability of its parts or subsystems was calculated with the dynamic programming method based on the control sequence method. And the optimized result of the ball screw actuator system was gotten with the system constraints conditions. The redundancy of components at all levels is obtained with the greatest reliability.

The novel Fe/Se soft magnetic material could be obtained easily by heating equal molar of selenium and iron powders. The saturation magnetization, residual magnetic field strength and coercive force of the material were 50.9 emu/g, 1.78 emu/g and 175.7 Oe, respectively, in accordance with the characteristic parameters of the soft magnetic materials. The material could catalyze the phenol oxidation reaction to produce p-benzoquinone selectively. As a selenium-containing magnetic substance, the material can give full play to the properties of selenium and magnetic materials at the same time, and thus may be of profound application values in industry.

Realizing six-degree-of-freedom movement for spindle tools in any posture is an important research direction for CNC machines. Existing spindle systems with parallel or cascaded structure, due to their complex mechanical structure, lead to serious abrasion on mechanical supports when rotating at a high or ultra-high-speed, which heats joint parts and worsens the dynamic characteristics. In light of technologies of motor and magnetic levitation, this paper proposed a multi-degree-of-freedom machine spindle system built on a maglev spherical active joint, and analyzed working principles of a three-dimensional rotating magnetic field generated by the rotor of maglev spherical active joint rotating around an arbitrary axis passing through a fixed spatial point. This paper also explored the effects of flow field of air gap formed in the maglev spherical active joint on the dynamic & static characteristics of joint based on aerodynamics, established mathematical models for the dynamic & static pressures and kinetic parameters of flow field of air gap, and, with simulation and experiment, investigated how the flow field of air gap impacts the static load-carrying capacity and the dynamic characteristics of joint.DOI: http://dx.doi.org/10.5755/j01.mech.24.5.19492

AB5-type hydrogen storage alloys have been extensively studied due to their wide applications, but their degradation process is still controversial, hindering the improvement in their cycling performance. In this work, the degradation mechanism of an AB5-type LaNi4.75Mn0.25 alloy with single CaCu5-type phase structure has been investigated based on its long-term hydrogen storage properties and the structural changes during cycling. It is found that within 1000 hydrogen absorption/desorption cycles in the temperature range of 343–383 K, the P-C-T curves remain a single plateau, but the plateau slope becomes steeper and the hydrogen storage capacity decreases. These degradation phenomena are caused by the structural evolution of the alloy including particle pulverization and crystal lattice damage. The internal driving force of the structural changes is found to be the microstrains generated during hydrogen absorption/desorption. But with cycling, the isotropic parameter c/a increases, decreasing the hysteresis and slowing down the degradation process.

By using selenium-directing technology, magnetic mesoporous silica-supported nano palladium catalyst (Pd/SiO2/Fe3O4-Se) for oxidative alkene cracking reactions could be synthesized in a relatively concise method. During the materials calcination process, decomposition and sublimation of selenium moieties of selenized Fe3O4 core could direct the formation of the micro-structures of nano materials more orderly, endowing the material overwhelmingly higher catalytic activity than the similar material prepared from unselenized Fe3O4. As the first report of synthesizing magnetic materials via the selenium-directing method, this work is of both science and application meanings and may inspire new ideas for the development of related novel materials.

Incoming wakes significantly affect vibration characteristics of rotating blades in turbomachines. This paper develops a periodic incoming wake mathematical model to consider the influence of pressure variations. Considering thickness variations along both the chord to reduce vibrations and the span to decrease centrifugal stress, a wake-induced vibration model based on rotating large deformation cantilever plates is established. Natural frequencies calculated by different methods show that the present method has a high degree of accuracy. And analysis of incoming wake-induced vibrations indicates the incoming wake model can analyze effects of important parameters of such wakes on vibration characteristics. With the aggravation of wakes induced-vibrations, geometric nonlinear vibrations become more remarkable, which indicates the necessity of large deflection analysis. Discussions on variable thickness demonstrate that increasing thickness on the fixed end or maximum thickness along the chord not only reduces vibrations caused by incoming wakes, but also decreases the centrifugal stress, which are two better ways to reduce this kind of vibrations.

It was found that, with selenium powder as the structure director, the Se/C hierarchical nanobelts (HNBs) could be fabricated by calcining selenized glucose at 500 °C in N2 atmosphere. In comparison with simple Se/C materials, the specific surface area of Se/C HNBs was obviously enhanced (9.93 m2/g vs. 1.02 m2/g), endowing the materials very strong ability to remove heavy metals (such as Cu, Ni and Cr) from their aqueous solution.

Rare-earth based AB5-type alloys are one of the most popular and potential hydrogen storage materials. However, their overall hydrogen storage performance, especially hydrogen absorption/desorption durability needs to be further optimized. In this study, the microstructure and long-term hydrogen absorption/desorption properties of La5-xCexNi4Co (x = 0.4, 0.5) and La5-yYyNi4Co (y = 0.1, 0.2) alloys are investigated. All the alloys are composed of CaCu5-type hexagonal single-phase structure. The addition of either Ce or Y increases the anisotropic c/a factor of cell lattices, thus enhancing the alloys' pulverization resistance and structural stability. Ce and Y elements also help to eliminate the second plateau in the alloys’ P–C-T curves and increase their application efficiency. In particular, La4.5Ce0.5Ni4Co alloy shows a single and long P–C-T plateau which reaches 95.5% of the full capacity compared with 67%–77% of the other three alloys. Furthermore, it experiences low microstrains and possesses high pulverization resistance during hydrogen absorption/desorption, exhibiting an excellent cycling retention of 96.0% after 1000 cycles. In addition, this alloy boosts the feeding hydrogen pressure from 1.5 MPa at room temperature to above 20 MPa at 175 °C with small hysteresis and flat and long plateau, showing a potential in the application of hydrogen compressor.

The working principle of the active asynchronous induction magnetic bearing is investigated in this paper. First, the mathematical model of radial force and torque for the magnetic bearing is established. Then, the corresponding control model of the system is proposed. Finally, the experimental simulation was carried out in MATLAB / SIMULINK environment, and the experimental results showed that the system has good stability and high robustness.

A new axial electric pump with permanent magnetic levitation was presented. First the basic structure, working principle and characteristic of the axial electric pump are introduced. Then the generation of magnetic suspension force, electromagnetic torque and axial force of the motor pump was analyzed. The research results may provide a theoretical foundation for the electromagnetism design of axial induction motor pump.

In this paper, a novel method for designing and manufacturing of nosal prosthesis is presented. Using the method, multiple point sets of the patient’s and volunteer’s faces can be generated by 3D white light inspection system based on special binocular cameras without any damages on their skin. Based on CAD technique, volunteer’s nose mesh was registered and fit in the patient’s face mesh .After be merged, the undersurface of the nasal prosthesis mesh can match the remnant tissue of deformed side perfectly. By rapid prototyping manufacturing machine, the nasal prosthesis can be produced with resin and in good agreement with the deformity area. In so far, integrating non-contact white light inspection,reverse engineering with rapid prototyping manufacturing technology and without any damages on patient’s skin, this approach allows us to generate custom-made nasal prostheses easily and rapidly .

The rotation and suspension of magnetic levitation joint rotor depends on the magnetic levitation force and electromagnetic torque produced after the joint is powered on. This paper presents an idea of differential control strategy. There is only a set of winding in upper or lower stator, and the magnetic levitation force and electromagnetic torque could be controlled by the magnitudes and phases regulating of the winding currents, then which make the motor operate stably. With MATLAB/Simunik software, the simulation of control system is made, and the results are analyzed

A new control structure scheme of magnetic levitationmotor is presented. Its working principle is introduced, andthe mathematical model of the magnetic levitation force isestablished based on principle of virtual displacement. Thedistribution characteristics of electromagnetic levitationforce and magnetic induction intensity of the motor areanalyzed with the finite element method

A tip-rub model is developed for nonlinear dynamics analysis of contact-induced vibrations of the rotating variable thickness plate under large deformations . Variable thickness, coupled with large deformations, contact-impact and centrifugal stiffening , increases complexity of the nonlinear system . Natural frequencies for different variable thickness are compared to indicate a great precision of the present method. Solution procedure for tip-rub has been proved to be in good agreement with existing experimental results. Numerical simulation for tip-rub reveals the requirement of large deformation analysis. Then special attention is given to nonlinear characteristics of the rotating rubbing plate with variable thickness. Results show that there are very rich and complex nonlinear dynamics of contact-induced vibrations of the rotating variable thickness plate under large deformations such as multi-period, bifurcation and chaotic motions. And effects of thickness strategies of exponential and linear decrease along the span used in engineering on nonlinear characteristics induced by tip-rub are investigated. Numerical results reveal that smaller thickness at the free end used to reduce centrifugal stress should not be too small to avoid aggravation of contact-induced bifurcation and chaos. Moreover, in order to obtain less centrifugal stress and weak chaotic behavior, there is an optimal thickness at the fixed end when the smaller thickness at the free end is unchanged. As the order of thickness function increasing, the trend of bifurcation and chaotic motions is gradually aggravated. It is better to choose a small order of thickness function to ensure stable operation.

This paper presents a novel Multi-Degree-of-Freedom magnetic levitation sphere driving joint. It analyses the relevance theory of air-gap magnetic energy of the mechanic and electric energy transformation while the magnetic levitation force and electromagnetic torque were generated by driving joint, which based on the principles of state reconstruction. It achieves state synchronization suspension control and self-test feedback control without sensor of the rotor. The simulation experiment shows that the state synchronization suspension control owns high precision and interference immunity.

The multi-degree-of-freedom spherical driving joint with direct bearing driven by spherical motor owns high mechanical integrity and has many advantages such as control and trajectory planning. This paper presents a novel multi-degree-of-freedom spherical reluctance driving joint with magnetic levitation, and analyses operation mechanism, and next deduces the joint’s magnetic conduction of the gap by means of the way to magnetic segmentation achieves the relationship between electrical and mechanical energy conversion, and then calculates the radial suspension force and the tangential suspension torque which spherical driving joint produces. The simulation experiments show that the system of driving joint has well static and dynamic characteristics.

According to the design requirements of solar water heater control system, based on characteristic of uncertainty of the water heater temperature and being unable to establish an accurate mathematical model, a fuzzy neural network control algorithm is applied to the control system. By use of the experimental data, the fuzzy neural network is trained offline by ANFIS toolbox, the program is written in C language, and a solar water heater control system based on STC90C52RC micro-controller is established.