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The working principle of the motor can cause unbalanced magnetic pull (UMP) between stator and rotor unavoidably. Previous research about nonlinear vibration excited by UMP was focused on the rotor supported by traditional mechanical bearings or gas bearings. However, the magnetic levitation rotor is particular due to the low rigidity provided by the active magnetic bearing (AMB). UMP amplifies rotor vibration in the resonant zone and further excites the nonlinear electromagnetic force, thus producing different vibration phenomena. The paper calculates rotor orbit, spectra analysis, and time-history plot with numerical methods and studies the influence of the rotation speed, eccentricity, key control parameters, and UMP on rotor dynamics in detail. Results illustrate displacement response spectra of the magnetic levitation rotor are quite different from previous research results. The appearing frequency components are inducted by universal formulas in this paper. Furthermore, research shows a slight adjustment of the control parameters affect significantly harmonic components and vibration characteristics. The research results have practical reference significance for fault diagnosis, feature recognition, and controller optimization of the AMB-rotor system.

Background:Triple-negative breast cancer (TNBC) is a high-risk breast cancer subtype, which accounts for 15% to 20% of all breast cancers and generally has a poor prognosis. TNBC patients have high recurrence post-surgery and high risk of metastasis to other organs. The tumor microenvironment (TME) plays important roles in the carcinogenesis, development, and metastasis of tumors. Methods: This study aimed to investigate the effects of immune and stromal cell-related genes on TNBC prognosis. The ESTIMATE algorithm was used to calculate the immune/stromal scores of TNBC samples from the GEO database. The samples were divided into high- and low- score groups and the differential expression genes were identified using the limma package within R. Functional enrichment and protein-protein interaction (PPI) network analyses revealed that these genes are primarily involved in immune responses. Results:Survival analysis in both GSE21653 and KM-plotter website showed that 36 genes were significantly related to disease-free survival (DFS) of TNBC. Another survival analysis by R package survival in GSE58812 indicated that 14 genes of 36 were greatly interrelated to DFS of TNBC. Moreover, the expression levels of some of these genes were verified through immunohistochemical staining and RT-qPCR. Finally, four genes importantly associated with TNBC prognosis were identified with Cox-LASSO analysis. Time-dependent receiver-operating characteristic (ROC) analysis displayed an area under the curve (AUC) of 0.95 for one-year survival rate, indicating the four genes performed very well for prognosis prediction. Conclusions:In conclusion, we identified four genes, including BIRC3, CD8A, GNLY and TRIM22, that are possibly associated with the TME and are potential prognostic and therapeutic markers of TNBC.

High temperature superconducting (HTS) magnetic bearing can operate in the harsh environment of low temperature and negative pressure with low loss and self-stability. Therefore, it has been gradually applied in flywheel energy storage, cryogenic liquid pump, cold compressor and some other cryogenic rotating machinery. The load-carrying performance of HTS magnetic bearing is affected by the cooling temperature of HTS directly. In this paper, the linear model is used to modify the temperature dependence to evaluate the influence of cooling temperature on load-carrying performance quantitatively, and the results are analyzed and displayed from the aspects of maximum levitation force, levitation stiffness and hysteresis effect. The research results of this paper have practical significance for the design and safe operation of HTS levitation system.

Active control of flexible rotors is a challenging issue in modern industries. This paper focuses on the synthesis of a mixed sensitivity robust controller for a linear parameter-varying (LPV) system. The objective is to control rotor vibration, especially when the rotor is passing the first two bending critical speeds. In the formulation of the problem for the controller, weighting functions are proposed based on the relationship between the desired shape of the open-loop transfer function and sensitivity functions of the closed-loop system. Recent research has highlighted the efficiency of mixed sensitivity robust controllers in stabilizing a wide range of magnetic bearing systems. Here, the method is extended to control the vibration of a piezoelectric bearing system. The experimental rotor features two unbalance-exited resonances within its operating range. Experimental results demonstrate good performance of the vibration reduction and the effectiveness of the design method.

In order to meet the training needs of Partial Discharge (PD) detection personnel, a PD detection training simulator is developed. The composition of the system and the functions of the modules are described, then the three-dimensional graphic engine based on Open Scene Graph (OSG) and the way of scene organization based on hierarchical tree are introduced, moreover, the methods of fault simulation and detection instrument simulation based on algorithm component library are presented. Application shows that the system can provide various detection schemes, and it is an ideal training tool for the detection personnel.

Hydrocarbons have high thermodynamic performances, belong to the group of natural refrigerants, and they are the main components in mixture Joule-Thomson low temperature refrigerators (MJTR). New evaluations of nucleate boiling contribution and nucleate boiling suppression factor in flow boiling heat transfer have been proposed for hydrocarbons. A forced convection heat transfer enhancement factor correlation incorporating liquid velocity has also been proposed. In addition, the comparisons of the new model and other classic models were made to evaluate its accuracy in heat transfer prediction.

In helium refrigeration system, high-speed centrifugal cold compressor is utilized to pumped gaseous helium from saturated liquid helium tank at low temperature and low pressure for producing superfluid helium or sub-cooled helium. Stall and surge are common unsteady flow phenomena in centrifugal cold compressors which severely limit operation range and impact efficiency reliability. In order to obtain the installed range of cold compressor, unsteady flow in the case of low mass flow or high pressure ratio is investigated by the CFD. From the results of the numerical analysis, it can be deduced that the pressure ratio increases with the decrease in reduced mass flow. With the decrease of the reduced mass flow, backflow and vortex are intensified near the shroud of impeller. The unsteady flow will not only increase the flow loss, but also damage the compressor. It provided a numerical foundation of analyzing the effect of unsteady flow field and reducing the flow loss, and it is helpful for the further study and able to instruct the designing.

In this paper, an experimental study on two-phase flow patterns (evaporation) for propane in a horizontal smooth tube is presented. The tests were conducted at various saturation pressures from 0.2 MPa to 0.4 MPa for different mass velocities from 70 kg/(m 2 s) to 180 kg/(m 2 s) and two heat fluxes (20.16 kW/m 2 and 37.1 kW/m 2 ) in the entire ranges of vapour qualities. Several flow pattern maps were compared with the experimental flow pattern data, especially for the intermittent/annular (I/A) transition line. Finally, a transition equation of intermittent/annular flow for propane was modified with an improved flow pattern map.