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Abstract Fault propagation is a common occurrence in traction drive control systems. The propagation of faults among components creates difficulties in traceability. Therefore, this paper focuses on the traction transmission control system and proposes a fault tracing method based on fault propagation. First, establish a fault propagation model that includes spatiotemporal characteristics. Then, extract the fault characteristics and the time it takes for faults to propagate at various observation points throughout system operation. Finally, match the spatiotemporal characteristics of the corresponding observation points in the fault propagation model, so as to determine the fault type and location, allowing for fault traceability. The proposed method’s feasibility is verified using a system example. The effectiveness of the proposed method in the traction drive control system was verified through system examples, which can meet the requirements of rapid fault tracing and is effective for weak faults.

ABSTRACTThe motion response of a ship in a cross sea is studied based on computational fluid dynamics. Firstly, according to the established numerical pool, and based on the Reynolds-averaged Navier–Stokes equations and the re-normalisation group K–ϵ turbulence model, the free surface is treated by the volume of fluid(VOF) method, and a numerical simulation method is established. The wave results obtained by the numerical simulation are compared with theoretical waves to verify the reliability of the method. Then, considering the DTMB5415 ship model, a prediction method for the ship’s motion in a cross sea is established by using an overlapping mesh and VOF technology. The influence of a cross sea on ship motion performance under different wave direction angles, different wave heights and for different periods is analyzed. In addition, a method is also established for studying the ship’s motion response based on potential flow theory, and it is found that ships sailing under superimposed waves will exhibit the phenomenon of beat vibration. Finally, by comparing the results obtained by the two methods, the consistency of the two methods is verified, which provides a strong basis for the safety assessment of ships in cross seas.

Objective: A BP neural network model was established to accurately determine the maturity of dough fermentation. Methods: Used machine vision technology to collect and process the pictures of bread fermentation process, obtained the quantitative information of the pictures, and a prediction model was established for bread fermentation degree based on BP neural network. Taking the time, area, instantaneous velocity, expansion rate, gray value energy, gray value relationship, gray value uniformity and gray value contrast as the input neurons, the regression model of relevant parameters was established. Results: The correlation between the above characteristic parameters and the fermentation process of bread was determined, which can effectively characterize the fermentation degree of bread; The results show that the accuracy of the prediction model based on BP neural network is 88.41%. Conclusion: The model can accurately determine the degree of bread fermentation and effectively improve the quality consistency in industrial bread production.

Aiming at the problem that traditional inverse reinforcement learning algorithms are slow,imprecise,or even unsolvable when solving the reward function owing to insufficient expert demonstration samples and unknown state transition probabilitie,a meta-reinforcement learning method based on relative entropy is proposed.Using meta-learning methods,the target task learning prior is constructed by integrating a set of meta-training sets that meet the same distribution as the target task.In the model-free reinforcement learning problem,the relative entropy probability model is used to model the reward function and combined with the prior to achieve the goal of quickly solving the reward function of the target task using a small number of samples of the target task.The proposed algorithm and the RE IRL algorithm are applied to the classic Gridworld and Object World pro-blems.Experiments show that the proposed algorithm can still solve the reward function better when the target task lacks a sufficient number of expert demonstration samples and state transition probabilities information

Two novel mixed-ligand coordination polymers, {[Co(tdc)(btrp)]·0.67DMF}n (1) and {[Zn2(bimb)2(tdc)2]·2H2O}n (2) involving 2,5-thiophenedicarboxylate (H2tdc), and bitopic flexible N-donor ligands, 1,3-bis(1,2,4-triazol-1-yl)propane (btrp) and 1,4-bis((1H-benzo[d]imidazol-1-yl)methyl)benzene (bimb), have been synthesized by the hydrothermal method and characterized via IR, elemental analysis, thermal analysis, and powder X-ray diffraction. The biological functional studies were performed; the treatment activity of the compounds on periodontitis and the specific mechanism was explored. First, the real-time RT-PCR was carried out to determine the inflammatory genes nf-κb and p53 relative expression in periodontal mucosal cells after treating with compounds 1 and 2. Then, the level of the inflammatory cytokine in the gingival crevicular fluid after treating with compounds was also determined by the ELISA detection kit.

BACKGROUND At present, research on the extraction separation and enrichment of gallium is mostly biased to the strong acidic system, which brings a safety risk to the operation and needs acid-proof apparatus. Furthermore, the procedure is easily contaminated, resulting in high background values. OBJECTIVES To develop a method for extraction separation and preconcentration of trace Ga under weakly acidic condition. METHODS Solid phase extraction medium for Ga was prepared by using modified large porous adsorption resin with cetyl-trimethyl-ammonium bromide and loading it with 2-ethylhexyl phosphonic acid-2-ethylhexyleste. The separation and enrichment conditions of solid phase extraction were studied in detail. RESULTS Experiments showed that the separation and enrichment of trace gallium was ideal when the extraction conditions were mild. The maximum recovery (99%) of Ga was achieved in sample solution with pH of 2.5. The determination parameters of gallium were optimized for oxygen doped air-acetylene flame atomic absorption spectrometry (FAAS), and the sensitivity was improved on that of the current method. The detection limit of the overall method (3σ) was 2.6ng/mL by IUPAC definition and the relative standard deviation (RSD, n=7) was 2.87%. The recoveries for spiked solution ranged from 95.7% to 102.0%, and a theory enrichment factor of 40 was obtained. CONCLUSIONS This method has been successfully applied to the determination of trace gallium in tap water, Chinese medicine and hydroponic vegetable samples. It is simple, quick and reliable.

A pump-jet propulsion system is composed of rotor, stator, and duct. The stator has the front stator type and the rear stator type; the conduit also has the acceleration conduit and the deceleration conduit two forms. It is difficult to design and evaluate the performance of a pump-jet propulsion system because of its complex structure and many changes in component parameters. Due to the limitation of time and cost in the design process of the pump-jet propulsion system, it is difficult to find the optimal scheme in the design space. However, under the guidance of an optimization algorithm, the automatic optimization method can fill the design space with a large number of design schemes. In this paper, the geometry reconstruction technique, hydraulic performance evaluation technique and optimization technique of the pump-jet propulsion system are combined to realize the automation of the whole design process. Firstly, the geometric modeling of the pump-jet propulsion system is completed by a full parametric modeling method, and then the hydrodynamic performance of the pump-jet propulsion system is calculated based on the numerical simulation technique. The radial parameters in the fully parametric configuration of the pump-jet propulsion system were selected as the optimization design variables, and the hydro-dynamic performance was optimized as the objective function. Finally, the pump-jet propulsion system optimization design system was constructed by using the global intelligent optimization algorithm. This study provides a theoretical basis and technical guidance for numerical calculation and configuration optimization design of pump-jet propulsion system.

A novel maximum power point tracking method based on sliding mode control and average state model of PV generation systems is developed. This method consists of two parts: term of constant control and term of index control. It is different from the conventional sliding mode control which uses a constant speed control law. The developed method uses a controllable sliding mode switching function which can automatically adjust the approaching speed, so as to enable the photovoltaic system to achieve fast dynamic response and stable output power. System simulations using MATLAB are performed. Compared with conventional methods, simulation results show that maximum power point tracking times for the novel method both in start-up phase and in cases of environmental changes can be shorten by more than 50%. A experimental platform of 150W PV system has been established to conduct tests. Experimental results show that the maximum power point tracking times both in start-up phase and in load stepping phase including the illumination change phase, can be significantly decreased. These results indicate that the developed method owns better dynamic response than constant speed control law. It can be used in photovoltaic generation system.

When a ship sails in an ice area, the ice could cause damage to ship hull and the propeller as well as the rudder. In the design process of an ice class propeller, the strength verification of the propeller has always been the focus of the design and research of the ice propeller. Based on the International Association of Classification Societies Unified Requirements for Polar Class (IACS Polar UR), it is required that the maximum torque from the propeller cannot exceed the required value to ensure the safety of the propeller shafting equipment. This paper investigates the hydrodynamic performance of the propeller under the condition of satisfying the propeller’s ice strength. A parametric propeller optimization design procedure was established in which the thrust coefficient and open water efficiency solved by CFD method were selected as the objective function and optimization target, the maximum ice torque was used as the optimization constraint under the condition that the ship’s shafting equipment remains unchanged, the propeller pitch, thickness, and camber at each radial direction were taken as the optimization design variables, and the optimization algorithm of SOBOL and NSGA-II was adopted. The interaction mode of propeller and ice was simulated by the method of explicit dynamics. The equivalent stress and displacement response of the blade during the cutting process of the ice propeller were calculated, monitoring the ice destruction process. The results show that the multi-objective Pareto optimal solution set of thrust coefficient and open water efficiency of the ice class propeller was formed at the design speed while maintain the maximum ice torque not exceeding the original ice torque.

The Energy Efficiency Design Index (EEDI) has been applied to ship carbon emission standards since 2013, ice ships subject to the Finnish Swedish Ice Class Rules (FSICR) also need to meet the requirements of EEDI. In this study, the engine power requirements by EEDI at different stages for the considered ice class ships with different ice classes (1C, 1B, 1A, 1A Super) are compared with engine power requirements obtained from the resistance calculated by FSICR or Lindqvist method. Three different bow shapes for the considered ice class ships and different pack ice coverage are studied. The results from FSICR or Lindqvist formula show that 1A Super ice classes for all considered bow shapes cannot meet the requirement by EEDI at Phase 2 and 3; For 1B and 1A class, some bow shapes can meet the EEDI requirement for all stages, but some cannot; For 1C class, all bow shapes can meet the EEDI requirements for all stages. The ship main engine power requirements under different pack ice concentration are studied and compared to EEDI requirements.

The effects of lanthanum and boron on the inclusion size distribution, microstructure, texture and magnetic properties of three non-oriented electrical steels have been studied. After final annealing, lanthanum effectively inhibited the precipitation of MnS precipitates and promoted the growth of grains, an addition of 0.0041 wt.% boron led to the precipitation of Fe2B particles and inhibited grain growth. On the other hand, steel containing 0.0055 wt.% lanthanum had the strongest {100} and {111} fiber texture and the weakest {112}〈110〉 texture among the steels. Compared to steel without lanthanum and boron, steel with 0.0050 wt.% lanthanum and 0.0041 wt.% boron obtained slightly stronger intensities of {100} and {111} fiber texture, and a little weaker intensity of {112}〈110〉 texture. Steel containing 0.0055 wt.% lanthanum achieved the best magnetic properties, whose core loss and magnetic flux density were 4.268 W/kg and 1.768 T, respectively.

The microstructure, morphologies of precipitates in directional solidified 50W600 non-oriented silicon steel with three cooling rates (0.095, 0.33 and 4.28 °C/s) were investigated. The results showed that the morphology of solid-liquid interface evolved from cellular to cellular dendritic, and then to dendritic with an increase of cooling rate. The grain size of specimen in the steady-state growth region decreased with increasing cooling rate. The precipitates in the steel were mainly four types as follows: AlN, MnS, AlN-MnS and Fe3C. The amount and volume fraction of precipitates firstly increased and then decreased with increasing cooling rate, and reached maximum values in the specimen with a cooling rate of 0.76 °C/s. The average size of precipitates decreased gradually with increasing cooling rate. The relationship between the average size of precipitates and cooling rate was D = 75.762·R−0.190.

As a target of insect growth regulators, the ecdysone receptor complex binds ecdysone agonists to regulate gene transcription, development, and growth. To understand the response of Lymantria dispar to methoxyfenozide, we studied receptor complex transcription profiles following larval exposure to methoxyfenozide, and observed important variations amongst post-embryonic stages. After the exposure of 2nd and 3rd instar larvae to LC5 and LC20 methoxyfenozide for 72 h, the transcription levels of ecdysone receptor complex genes were mainly upregulated in 2nd instar larvae, but downregulated in 3rd instar larvae. These results provide expression characteristics of the ecdysone receptor complex in L. dispar larvae after methoxyfenozide exposure.

Six stages of database system design were introduced which includes requirements analysis stage, concept and structure design stage, logic structure design stage, physical structure design stage, implementation stage, and stage of operation and maintenance. Then current research situation of database system was described by examples of distributed database system, knowledge base system and active database system. Finally, current research focus and development trend were pointed out combining with introduction of data warehouse, engineering database, statistical database, space database, etc.

Based on the perturbation formulae of the spin Hamiltonian parameters (SHPs), i,e,. g factors gx, gy, gz, and hyperfine structure constants Ax, Ay, Az, for a 3d7 ion in rhombically distorted octahedra, the defect structure and the experimental EPR spectra are theoretically investigated for the rhombic Co2+ centre in ZnWO4. Due to the Jahn-Teller effect, the impurity ion Co2+ on host Zn2+ site is found to undergo the local rhombic elongation distortion, characterized by the axial elongation ΔZ (≈ 0.157 Å) of the impurity-ligand bonds and the perpendicular distortion angle Δф (≈ 3.5°) related to an ideal octahedron. Compared with host Zn2+ site in ZnWO4, the Co2+ centre exhibits a more regular oxygen octahedron. All the calculated SHPs show good agreement with the observed values. The present work may be helpful to understand the local structures and properties of metal tungstate with transition-metal dopants.

The g factors and superhyperfine parameters of the tetragonal [Fe(CN)4·(CN)Cl]5 group in NaCl are theoretically investigated from the perturbation formulas of these parameters for a tetragonally elongated octahedral low spin (S=1/2) 3d7 cluster. This center is ascribed to the substitutional Fe+ on host Na+ site associated with one of the axial ligands CN– replaced by Cl–. Since the crystal-fields arising from the axial Cl– and CN– ions are weaker than those of the four planar CN–, the impurity center is characterized as the tetragonally elongated octahedron. The calculated g factors and superhyperfine parameters show reasonable agreement with the measured values. The results are discussed.