Paradoxical Septal Motion after Uncomplicated Cardiac Surgery: A Consequence of Altered Regional Right Ventricular Contractile Patterns

Paroxysmal interventricular septal motion (PSM) is the movement of the septum toward the right ventricle (RV) during cardiac systole. It occurs frequently after uncomplicated cardiac surgery (CS), including coronary bypass (on-pump and off-pump), valve repair or replacement, and with all types of incisions (sternotomy or mini-thoracotomy). It sometimes resolves quickly but may persist for months or become permanent. Global RV systolic function, stroke volume and ejection fraction remain normal after uncomplicated CS, but regional contractile patterns are altered. There is a decrease in longitudinal shortening but an increase in transverse shortening in the endocardial and epicardial right ventricular muscle fibers, respectively. PSM is a secondary event as there is no loss of septal perfusion or thickening. The increased RV transverse shortening (free wall to septal fibers) may modify septal movement resulting in PSM that compensates for the reduced RV longitudinal shortening, thus preserving normal global right ventricular function.

Research on the Effect of Texture on Wear Performance of High-Pressure Piston Pump Valve Pair

In this paper, the surface wear performance of the valve pair of a high-pressure axial piston pump is improved. Firstly, the friction and wear tests are carried out for different materials of the axial piston pump valve pair. Moreover, the friction and wear behavior of the valve pair contact is studied. A valve pair material that is more suitable for processing surface texture is chosen. Friction and wear models of a valve pair based on degradation coefficient are proposed and wear conditions of different textures are calculated. Lastly, the texture with the best anti-wear effect is selected. Finally, the selected textures are experimentally validated by laser processing. The results show that a long strip with a diameter of 400 μm, a depth of 20 μm, and an area ratio of 2% can effectively reduce wear. Through comparative analysis, it is concluded that the texture shape has the least influence on the wear of the valve pair. On the other hand, the area ratio of the texture has the greatest effect on the wear of the valve pair. As the diameter of the texture increases, the wear of the valve pair gradually decreases. As the texture depth increases, the wear amount of the valve pair shows a downward trend.

Pulsation Simulation and Energy Consumption Analysis of Series Pump Valve Cooperative Control Hydraulic System

In order to reduce the pulsation and the energy consumption of the hydraulic system, the series pump and valve cooperative control hydraulic system is designed, and the pulsation simulation and energy consumption analysis of it is carried out. Firstly, the working principle of series pump valve co control system is studied. Secondly, the mathematical model of series pump valve cooperation control system is established. And then the Controller of series pump valve cooperation control system is designed. Finally, the simulation analysis of the proposed hydraulic system is carried out, and results show that the proposed system has high stability and low energy consumption.

Analysis of the Movement Characteristics of the Pump Valve of the Mine Emulsion Pump Based on the Internet of Things and Cellular Automata

Studying the movement characteristics of the coalmine emulsion pump valve is of great significance for optimizing the dynamic response characteristics of the pump valve, reducing the hysteresis effect, and improving the volumetric efficiency. This article combines the Internet of Things (IoT) and cellular automata techniques to investigate the movement characteristics of the valve of the emulsion pump. Based on Adolf’s exact differential equation and Runge–Kutta iterative method, the movement displacement and movement of the pump valve spool speed curve are computed using Scilab software. We employ cellular automata and AMESim to establish the hydraulic system model of emulsion pump and analyze the movement characteristics of pump valve movement displacement, speed, stability, and closing hysteresis through simulation. Finally, the IoT techniques and a test device are used to evaluate the movement displacement of the pump valve. The experimental results verify the feasibility of using the proposed method to study the pump valve motion characteristics, greatly reduce the cost of testing and parameterized design, and contribute to the development of highly reliable and efficient emulsion pump valves.

A novel pump-valve coordinated controlled hydraulic system for the lower extremity exoskeleton

In order to reduce the weight and improve the energy efficiency of the lower extremity exoskeleton, a novel pump-valve coordinated controlled (PVCC) hydraulic system is presented. This hydraulic system only uses one electro-hydrostatic unit (EHU) and two valves to drive two hydraulic cylinders at the hip and knee of the lower extremity exoskeleton. The PVCC hydraulic system has the advantage of high energy conversion efficiency of the electro-hydrostatic actuator (EHA), which consists of one EHU and one hydraulic cylinder. To meet the requirements of the moment and speed of each joint of the exoskeleton, the proportional valve and on-off valve are added to adjust the flow into two hydraulic cylinders. The performance of EHU is tested by some hydraulic experiments, and the performance of the PVCC hydraulic system is analyzed by AMESim. The results show that the novel hydraulic system can only use one EHU to drive two hydraulic cylinders simultaneously under the premise of meeting the functional requirements of the exoskeleton.

The Use of Acoustic Emission Elastic Waves for Diagnosing High Pressure Mud Pumps Used on Drilling Rigs

Although mud pumps are vital components of a drilling rig, their failures are frequent. The identification of technical condition of these high-pressure piston pumps is difficult. There are no reliable criteria for the assessment of mud pump condition. In this paper, faults of the pump valve module are identified by means of acoustic emission (AE) signals. The characteristics of these signals are extracted by wavelet packet signal processing. This method has been verified by experiments conducted on a NOV (National Oilwell Varco) -made triplex 14-P-220 mud pump (mounted in the drillship). The results show that the wavelet packet signal processing method can effectively extract the frequency band energy eigenvalues of the signals. Besides, some operational problems associated with high pressure piston mud pumps are presented. A non-invasive method for diagnosing the technical condition of such pumps is being developed at the Maritime University of Szczecin.