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Rubber isolator is commonly used as vibration isolation device for piston pump, and the vibration of piston pump can be effectively reduced by adjusting the dynamic stiffness of rubber isolator. In this paper, in order to study the effect of rubber isolator's dynamic stiffness on the dynamic of seawater hydraulic piston pump (SWHPP), four kinds of rubber isolators with different dynamic stiffness were selected. An experimental modal analysis (EMA) experiment was conducted to study the influence of rubber isolator's dynamic stiffness on the natural frequency of SWHPP. The experimental results indicated that the natural frequency of the pump structure decreased as the dynamic stiffness of rubber isolator increased. Then, the influence of the rubber isolator's dynamic stiffness on the vibration of SWHPP was further studied, and conclusions can be obtained that: the vibration level of the pump decreases with the dynamic stiffness of rubber isolator increases. For the four kinds of rubber isolators, when the dynamic stiffness of rubber isolator is 5800N/cm, the vibration reduction effect of the isolator is the best, which reaching 38%. In addition, the dynamic stiffness of rubber isolator mainly affects the vibration of the pump in the frequency of 0–20 Hz.

An investigation into the dynamic behavior of the piston pump is an important method to reduce its vibration and noise. In this paper, an approach to predict the dynamics of a seawater hydraulic piston pump (SWHPP) from output-only transmissibility measurements is introduced. In order to eliminate the harmonic interference generated by spindle rotation, the excitation in this method is the pressure which caused by the SWHPP operating at a constant speed and under different loading conditions. The first four modes of the SWHPP were estimated utilizing the method proposed in this paper, and the influence of the pressure on the dynamics of the SWHPP structure was further studied. The experimental results indicated that peak occurred around the frequency of 20 Hz, and the reason is that the estimated second-order natural frequency (19.8 Hz) is near to the frequency of 20 Hz which is the excitation frequency of the swash plate and the flat valve of the SWHPP. In addition, this method can identify modal parameters of the piston pump structure in the working state, so it can effectively predict the dynamic behaviors of the piston pump.

Maneuverability is one of the most important performances of underwater vehicles. To improve the maneuverability of underwater vehicles, a high-pressure waterjet propulsion system combined with a Thrust Vector Control System (TVCS) was presented, which controlled the sailing trajectory through adjusting the waterjet deflection angle and thrust vector instead of rudders and sterns. The TVCS was established in the form of 3RPS Parallel Manipulator and the position feedback was provided by measuring the displacements of three actuator cylinders. The relationship between the thrust direction and the displacements of the actuator cylinders was established through the procedure of solving an inverse kinematics problem. Simultaneously, the motion transformation function of the system was derived, and the Fuzzy-PID strategy was adopted. Accordingly, the Simulink model was built, and the simulation indicated that the system had good performance. In addition, the sailing trajectory was obtained, and the results showed that the turning diameter was 78 m, and it was independent of thrust and sailing speed. The underwater vehicle utilizing high-pressure water jet propulsion with TVCS had good maneuverability at either high or low speed conditions.

Hydropneumatic suspension has the characteristics of nonlinear stiffness, nonlinear friction damping, and nonlinear hydraulic damping, and therefore, it has been widely applied to heavy vehicles. A hydropneumatic suspension with a special structure was proposed and studied in this paper. The nonlinear quarter-vehicle model was built by using Newton’s laws according to its configuration. Then, this nonlinear mathematic model was linearized through the statistical linearization method on the basis of random vibration theory. Next, the transfer functions of the suspension system subjected to random road excitation were built according to the statistical linearization model and the power density spectrum approach. In addition, the responses of vehicle body acceleration, tire relative dynamic load, and suspension deflection with respect to the wideband random excitation due to road roughness were obtained according to the James formula. Next, the influences of the equivalent damping ratio and the equivalent frequency ratio on vehicle riding comfort, riding safety, handing stability, and suspension reliability were analyzed through simulations. These results provided the basic principles for selecting the reasonable hydropneumatic suspension parameters.

Water jet propulsion is a crucial technology for ships and underwater vehicles. A high-pressure water jet propulsion system was proposed in this paper. The fundamental thrust theory of this system was studied and the influence of cavitation on the thrust was investigated. First, the mathematical model of thrust based on momentum equation coupled with cavitation theory was established. Then, the performance of cavitation two-phase flow field was simulated through computational fluid dynamics (CFD), and the thrust was calculated according to these simulation results. Finally, experiments were conducted on a test rig to study its force performance. The experimental results showed that the maximum thrust reached 4000 N with a 16-mm nozzle at the flow rate of 1200 L/min. The experimental results were both higher than the simulation and the calculation results. The theoretical force model coupled with the cavitation model was better matched with the experimental results.

Few effective insulation state detection methods for power capacitor can be used in field. In this paper, a power capacitor insulation state detection method based on polarization-depolarization current is proposed. Firstly, the basic principles of the method are discussed. Then, two characterized parameters are conducted based on polarization and depolarization currents, which are DC conductivity and 0.1Hz dielectric loss. A test device based on this method is developed to evaluate the insulation state of power capacitor with different aging conditions. The test results showed that the polarization and depolarization currents increased along with the aging conditions. The DC conductance and 0.1Hz dielectric loss also increased along with the aging conditions. The test indicated the polarization-depolarization current method is suitable for power capacitor insulation state detection.

Centrifugal pumps are widely used in modern industry, and blades are the key parts of it. The cracks on blades may result in a very serious consequence. In this paper, a fault diagnosis method based on principal component analysis (PCA) and Gaussian mixed model (GMM) was proposed, which combined signal processing and knowledge. Also, the theory model of proposed methods was established, and Expectation Maximization (EM) algorithm was used to make the model converge. PCA was used to reduce the data dimensionalities and increase the feature resolution, and GMM was used as classifier for crack fault. In order to verify the diagnostic effect of the model, the experimental bench of centrifugal pump was established, and various working conditions of the centrifugal pump were simulated. Experimental results showed that the classifier based on these parameters performed very well in data testing.

The Sino–Zambian Cooperation project provides national catchment sediment geochemical data for 58 elements including Cu and Co from 746 sediment samples at 736 sampling sites, corresponding to a sampling density of about 1 site per 1000 km2. The Cu and Co were determined by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) under strict quality control using field duplicates, standard reference materials and analytical replicate samples. The 95% ranges (2.5%–97.5%) of Cu and Co concentrations were from 1.8 to 57.81 × 10−6 and from 0.54 to 22.83 × 10−6, respectively, reflecting locally unevenness distributions. The median values of Cu and Co are 5.77 × 10−6 and 2.98 × 10−6, respectively. The most noticeable anomalous patterns of Cu and Co are distributed between Lusaka and Solwezi (Lufilian Arc Belt) with the trend of increasing concentrations from southeast to northwest. The all spatial distribution patterns of Cu and Co in tectonic units, drainage basins and geomorphological landscapes show good relations with parent rocks, climate, Cu (Co) deposits and smelting plants in Lufilian Arc Belt. The Cu and Co concentrations show metallogenic belts in Mkushi area, between Lusaka and Solwezi areas, and in Livingstone area.

Rubber isolator commonly used as support of piston pump, and the stiffness and damping nonlinearity of rubber isolator will significantly affect the vibration characteristics of piston pump. In this paper, two kinds of rubber isolators were selected, and the effect of pressure excitation amplitude on the vibration isolation effect of rubber isolator under different pressure conditions is studied. The vibration of piston pump and the base with different rubber isolators are further measured, and the vibration isolation effect of rubber isolators under different discharge pressure of piston pump is calculated. Experimental results show that: with the increase of pressure, the vibration of the piston pump and the base increases, on the contrary, the vibration isolation effect decreases. The vibration of the pump and the base with rubber isolator BE400 is lower than that of BH400. This study can contribute to the vibration and noise control of piston pump in engineering.