Multi-blade rubbing characteristics of the shaft-disk-blade-casing system with large rotation

Blade rubbing faults cause detrimental impact on the operation of aeroengines. Most of the existing studies on blade rubbing in the shaft-disk-blade-casing(SDBC) system have overlooked the elastic deformation of the blade, while some only consider the whirl of the rotor, neglecting its spin. To address these limitations, this paper proposes a dynamic model with large rotation for the SDBC system. The model incorporates the spin and whirl of the rotor, enabling the realistic reproduction of multiblade rubbing faults. To verify the accuracy of the SDBC model with large rotation and demonstrate its capability to effectively consider the rotational effects such as the centrifugal stiffening and gyroscopic effects, the natural characteristics and dynamic responses of the proposed model are compared with those obtained from reported research and experimental results. Furthermore, the effects of the rotating speed, contact stiffness,and blade number on the dynamic characteristics of the SDBC system with multi-blade rubbing are investigated. The results indicate that the phase angle between the rotor deflection and the unbalance excitation force increases with the increasing rotating speed,which significantly influences the rubbing penetration of each blade. The natural frequency of the SDBC system with rubbing constrain can be observed in the acceleration response of the casing and the torsional response of the shaft, and the frequency is related to the contact stiffness. Moreover, the vibration amplitude increases significantly with the product of the blade number under rubbing, and the rotating frequency approaches the natural frequency of the SDBC system. The proposed model can provide valuable insight for the fault diagnosis of rubbing in bladed rotating machinery.

Computing large deviation prefactors of stochastic dynamical systems based on machine learning

We present a large deviation theory that characterizes the exponential estimate for rare events in stochastic dynamical systems in the limit of weak noise.We aim to consider a next-to-leading-order approximation for more accurate calculation of the mean exit time by computing large deviation prefactors with the aid of machine learning.More specifically,we design a neural network framework to compute quasipotential,most probable paths and prefactors based on the orthogonal decomposition of a vector field.We corroborate the higher effectiveness and accuracy of our algorithm with two toy models.Numerical experiments demonstrate its powerful functionality in exploring the internal mechanism of rare events triggered by weak random fluctuations.

Security Vulnerability Analyses of Large Language Models (LLMs) through Extension of the Common Vulnerability Scoring System (CVSS) Framework

Large Language Models (LLMs) have revolutionized Generative Artificial Intelligence (GenAI) tasks, becoming an integral part of various applications in society, including text generation, translation, summarization, and more. However, their widespread usage emphasizes the critical need to enhance their security posture to ensure the integrity and reliability of their outputs and minimize harmful effects. Prompt injections and training data poisoning attacks are two of the most prominent vulnerabilities in LLMs, which could potentially lead to unpredictable and undesirable behaviors, such as biased outputs, misinformation propagation, and even malicious content generation. The Common Vulnerability Scoring System (CVSS) framework provides a standardized approach to capturing the principal characteristics of vulnerabilities, facilitating a deeper understanding of their severity within the security and AI communities. By extending the current CVSS framework, we generate scores for these vulnerabilities such that organizations can prioritize mitigation efforts, allocate resources effectively, and implement targeted security measures to defend against potential risks.

Implementation of Digital Classroom State System for Teachers and Students Based on Large Models

Deep learning has become a hot field of artificial intelligence,and the deep learning large model framework has become a bridgehead for the active layout of Chinese and foreign technology companies.Large models play a significant role in the application field,greatly improving the efficiency of training and optimization,and contributing to the landing of many innovative artificial intelligence tools.Based on the Chinese PaddlePaddle large model framework,an application system is designed in combination with the intelligent classroom teaching scenario,which uses machine vision algorithms to distinguish and present teachers’and students’behaviors,that is,the digitization and multi-classification scheme of class character states.After having digital data,data analysis can be carried out to evaluate the class status of teachers and students,and the traditional subjective judgment such as peacetime grades and teaching ability can be upgraded to the objective judgment of artificial intelligence.

Association of overall survival benefit of radiotherapy with progression-free survival after chemotherapy for diffuse large B-cell lymphoma:A systematic review and meta-analysis

Objective:To evaluate whether improved progression-free survival(PFS)from radiotherapy(RT)translates into an overall survival(OS)benefit for diffuse large B-cell lymphoma(DLBCL).Methods:A systematic literature search identified randomized controlled trials(RCTs)and retrospective studies that compared combined-modality therapy(CMT)with chemotherapy(CT)alone.Weighted regression analyses were used to estimate the correlation between OS and PFS benefits.Cohen’s kappa statistic assessed the consis-tency between DLBCL risk-models and PFS patterns.Furthermore,the benefit trend of RT was analyzed by fitting a linear regression model to the pooled hazard ratio(HR)according to the PFS patterns.Results:For both 7 RCTs and 52 retrospective studies,correlations were found between PFS HR(HRPFS)and OS HR(HROS)at trial level(r=0.639-0.876),and between PFS and OS rates at treatment-arm level,regardless of CT regimens(r=0.882-0.964).Incorporating RT into CT increased about 18%of PFS,and revealed a different OS benefit profile.Patients were stratified into four CT-generated PFS patterns(>80%,>60-80%,>40-60%,and≤40%),which was consistent with risk-stratified subgroups(kappa>0.6).Absolute gain in OS from RT ranged from≤5%at PFS>80%to about 21%at PFS≤40%,with pooled HROS from 0.70(95%CI,0.51-0.97)to 0.48(95%CI,0.36-0.63)after rituximab-based CT.The OS benefit of RT was predominant in intermediate-and high-risk patients with PFS≤80%.Conclusion:We demonstrated a varied OS benefit profile of RT to inform treatment decisions and clinical trial design.

Retrospect and Prospect of Excitation Systems of Large Size Turbogenerators

This paper briefs the developmental course, manufacturing and applications, as well as future prospect of excitation systems of large size turbogenerators in China, emphatically expounds the advantages of seif-excitation systems with potential source reetifiers and matters needing to be noted during dissemination and application of them.

Nonlinear formulation for flexible multibody system with large deformation

In this paper, nonlinear modeling for flexible multibody system with large deformation is investigated. Absolute nodal coordinates are employed to describe the displacement, and variational motion equations of a flexible body are derived on the basis of the geometric nonlinear theory, in which both the shear strain and the transverse normal strain are taken into account. By separating the inner and the boundary nodal coordinates, the motion equations of a flexible multibody system are assembled. The advantage of such formulation is that the constraint equations and the forward recursive equations become linear because the absolute nodal coordinates are used. A spatial double pendulum connected to the ground with a spherical joint is simulated to investigate the dynamic performance of flexible beams with large deformation. Finally, the resultant constant total energy validates the present formulation.

New risk factors and new tendency for central nervous system relapse in patients with diffuse large B-cell lymphoma:a retrospective study

Background: In patients with difuse large B?cell lymphoma(DLBCL), central nervous system(CNS) relapse is uncom?mon but is nearly always fatal. This study aimed to determine the risk factors for CNS relapse in DLBCL patients and to evaluate the eicacy of rituximab and intrathecal chemotherapy prophylaxis for CNS relapse reduction.Methods: A total of 511 patients with newly diagnosed DLBCL treated at the Sun Yat?sen University Cancer Center between January 2003 and December 2012 were included in the study. Among these patients, 376 received R?CHOP regimen(rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) as primary treatment, and 135 received CHOP regimen(cyclophosphamide, doxorubicin, vincristine, and prednisone) as primary treatment. Intrathe?cal chemotherapy prophylaxis(methotrexate plus cytarabine) was administered to those who were deemed at high risk for CNS relapse. In the entire cohort and in the R?CHOP set in particular, the Kaplan–Meier method coupled with the log?rank test was used for univariate analysis, and the Cox proportional hazards model was used for multivariate analysis. Diferences were evaluated using a two?tailed test, and P < 0.05 was considered signiicant.Results: At a median follow?up of 46 months, 25(4.9%) patients experienced CNS relapse. There was a trend of reduced occurrence of CNS relapse in patients treated with rituximab; the 3?year cumulative CNS relapse rates were 7.1% in CHOP group and 2.7% in R?CHOP group(P = 0.045). Intrathecal chemotherapy prophylaxis did not confer much beneit in terms of preventing CNS relapse. Bone involvement [hazard ratio(HR) = 4.21, 95% conidence interval(CI) 1.38–12.77], renal involvement(HR = 3.85, 95% CI 1.05–14.19), alkaline phosphatase(ALP) >110 U/L(HR = 3.59, 95% CI 1.25–10.34), serum albumin(ALB) <35 g/L(HR = 3.63, 95% CI 1.25–10.51), treatment with rituxi?mab(HR = 0.34, 95% CI 0.12–0.96), and a time to complete remission ≤ 108 days(HR = 0.22, 95% CI 0.06–0.78) were independent predictive factors for CNS relapse in the entire cohort. Bone involvement(HR = 4.44, 95% CI 1.08–18.35), bone marrow involvement(HR = 11.70, 95% CI 2.24–60.99), and renal involvement(HR = 10.83, 95% CI 2.27–51.65) were independent risk factors for CNS relapse in the R?CHOP set.Conclusions: In the present study, rituximab decreased the CNS relapse rate of DLBCL, whereas intrathecal chemo?therapy prophylaxis alone was not suicient for preventing CNS relapse. Serum levels of ALB and ALP, and the time to complete remission were new independent predictive factors for CNS relapse in the patients with DLBCL. In the patients received R?CHOP regimen, a trend of increased CNS relapse was found to be associated with extranodal lesions.

Large power analysis of switched reluctance machine system for coal mine

The conventional structures in the Switched Reluctance machines are introduced, such as three-phase 12/8 structure Switched Reluctance machine, three-phase 6/4 structure Switched Reluctance machine, four-phase 16/12 structure Switched Reluctance machine, and four-phase 8/6 structure Switched Reluctance machine. Three-phase 12/8 structure Switched Reluctance machine is the best choice for the large power Switched Reluctance machine system in coal mines. The asymmetric bridge power converter main circuit and the bifilar winding power converter main circuit are also introduced. Three-phase asymmetric bridge power converter main circuit is the best choice for the large power Switched Reluctance machine system in coal mines. The magnetic paths of the designed large power motor are given with one phase excitation and double phases excitation. The phase current waveforms are also given.

Stiffness of Postural Alignment System Based on 3-Axis Actuators for Large Aircraft Components

Aircraft digital flexible assembly fixture and technologies are widely used in developed countries, while the traditional jig-based assembly mode is still used in China. The application study of aircraft digital flexible assembly system is just beginning in our country recently. To meet the requirements of automated posture alignment and join in digital assembly system for large aircraft components, a novel fitting fixture called 3-axis actuator is developed. On the basis of the actuators, three kinds of posture alignment system for large aircraft components are proposed, including the non-redundant system, the redundant actuating system, and the redundant leg system, and their constitutions and properties are introduced. Through deriving the feeding transmission stiffness model of single actuator and analyzing the inverse kinematics of these systems, the relationship between the external force and the changes of position and orientation of large aircraft component is obtained, and then the postural alignment stiffness models are established. With the method mentioned above, the postural alignment stiffness of three systems is computed by using the algebraic formulate, and the results show that redundant properties can increase system＇s postural alignment stiffness. As an example, a optimized layout of the assembly system for a given model of aircraft is developed, the results of application show that the layout has many advantages, such as high accuracy, stiffness, stability, reliability, efficiency and flexible, which can satisfy the requirement of aircraft digital assembly system well. The proposed study of postural alignment stiffness for different systems can supply the theoretic support for the optimization layout design of aircraft digital assembly system, and contribute to evaluate the system working performance of systems.

Thermal stratification level of low sidewall air supply with air-conditioning system in large space

The thermal stratification level of low sidewall air supply system in large space was defined. Depending on the experiment of low sidewall air supply in summer 2008,the thermal stratification level was studied by simulation. Based on the simulation of experiment condition,the air velocity and vertical temperature distribution in a large space were simulated at different air-outlet velocities,and then the thermal stratification level line was obtained. The simulation results well match with the experimental ones and the average relative error is 3.4%. The thermal stratification level is heightened by increasing the air-outlet velocity with low sidewall air supply mode. It is concluded that when air-outlet velocity is 0.29 m/s,which is the experimental case,a uniform thermal environment in the higher occupied zone and a stable stratification level are formed. When the air-outlet velocity is low,such as 0.05 m/s,the thermal stratification level is too low and the air velocity is too small to meet the human thermal comfort in the occupied zone. So,it would be reasonable that the air-outlet velocity may be designed as 0.31 m/s if the height of the occupied zone is 2 m.

Systemic immune inflammation index, ratio of lymphocytes to monocytes, lactate dehydrogenase and prognosis of diffuse large Bcell lymphoma patients

BACKGROUND In malignant tumors,inflammation plays a vital role in the development,invasion,and metastasis of cancer cells.Diffuse large B-cell lymphoma(DLBCL),the most common malignant proliferative disease of the lymphatic system,is commonly associated with inflammation.The international prognostic index(IPI),which includes age,lactate dehydrogenase(LDH),number of extranodal lesions,Ann Arbor score,and Eastern Cooperative Oncology Group(ECOG)score,can evaluate the prognosis of DLBCL.However,its use in accurately identifying highrisk patients and guiding treatment is poor.Therefore,it is important to find novel immune markers in predicting the prognosis of DLBCL patients.AIM To determine the association between the systemic immune inflammation index(SII),ratio of lymphocytes to monocytes(LMR),ratio of LMR to LDH(LMR/LDH),and prognosis of patients with DLBCL.METHODS A total of 68 patients diagnosed with DLBCL,treated in our hospital between January 2016 and January 2020,were included.χ2 test,Pearson’s R correlation,Kaplan Meier curves,and Cox proportional risk regression analysis were used.The differences in the SII,LMR,and LMR/LDH among patients with different clinicopathological features were analyzed.The differences in progression-free survival time among patients with different SII,LMR,and LMR/LDH expressions and influencing factors affecting the prognosis of DLBCL patients,were also analyzed.RESULTS The LMR and LMR/LDH in patients with Ann Arbor stage III–IV,ECOG score≥2,and SII,IPI score 2–5 were significantly higher than those of patients with Ann Arbor stage I-II and ECOG score<2(P<0.05).Patients with high SII,LMR,and LMR/LDH had progression-free survival times of 34 mo(95%CI:32.52–38.50),35 mo(95%CI:33.42–36.58)and 35 mo(95%CI:33.49–36.51),respectively,which were significantly lower than those with low SII,LMR,and LMR/LDH(P<0.05);the SII,LMR,and LMR/LDH were positively correlated(P<0.05).Cox proportional risk regression analysis showed that the SII,LMR,and LMR/LDH were influencing factors for the prognosis of DLBCL patients(hazard ratio=1.143,1.665,and 1.704,respectively;P<0.05).CONCLUSION The SII,LMR,and LMR/LDH are related to the clinicopathological features of DLCBL,and they also influence the prognosis of patients with the disease.

A Systemic Approach to Integrated E-maintenance of Large Engineering Plants

Large engineering plants （LEPs） have certain unique features that necessitate a maintenance strategy that is a combination of both time and condition based maintenance. Although this requirement is appreciated to varying degrees by asset owners, applied research leading to a systematic development of such a maintenance strategy is the need of the day. Such a strategy should also adopt a wholesome ＂systemic＂ approach so that the realization of the overall objectives of maintenance is maximized. E-maintenance has several potential benefits for large engineering plants. In this paper, a three pronged strategy is suggested for the successful implementation of e-maintenance for LEPs. Firstly, an integrated condition and time based maintenance framework is proposed for LEPs. Secondly, reference is drawn to models for condition and time based maintenance at systemic levels. As a part of the ab initio development of a condition monitoring system for a LEP, one of the characteristics of the condition monitoring system, namely, predictability, is discussed in detail as a sample for a systemic study. Thirdly, emphasis is laid on the information and expertise available in the domain of plant design, operation and maintenance and the same is tapped for incorporation in maintenance decision making.

Simulation of Surface Wave with Large Eddy Simulation in σ-Coordinate System

A three dimensional numerical model in the σ coordinate system is developed to study the problem of waves. Turbulence effects are modeled by a subgrid scale (SGS) model with the concept of large eddy simulation (LES). The σ coordinate transformation is introduced to map the irregular physical domain of the wavy free surface and uneven bottom onto the regular computational domain of the shape of rectangular prism. The operator splitting method, which splits the solution procedure into the advection, diffusion, and propagation steps, is used to solve the modified Navier Stokes Equation. The model is used to simulate the propagation of solitary wave and wave passing over a submerged breakwater. Numerical results are compared with available analytical solutions and experimental data in terms of velocity profiles, free surface displacement, and energy conservation. Good agreement is obtained. The method is proved to be of high accuracy and efficiency in simulating surface wave propagation and wave structure interaction. It is suitable for the large and irregular physical domain, and requiring the non uniform grid system. The present work provides a foundation for further studies of random waves, wave structure interaction, wave discharge interaction, etc.

Remote Control and Telemetry System for Large-scale Model Test at Sea

Physical testing of large-scale ship models at sea is a new experimental method.It is a cheap and reliable way to research the environment adaptability of a ship in complex and extreme wave conditions.It is necessary to have a stable experimental system for the test.Since the experimental area is large, a remote control system and a telemetry system are essential, and were designed by the authors.An experiment was conducted on the Songhuajiang River to test the systems.The relationship between the model's speed and its electromotor's revolutions was also measured during the model test.The results showed that the two systems make it possible to carry out large-scale model tests at sea.

Large System Analysis of Downlink C-RAN with Phase Noise and Fronthaul Compression

This paper studies the effect of phase noise and fronthaul compression on a downlink cloud radio access network(C-RAN), where several remote radio heads(RRHs) are coordinated to communicate with users by a baseband unit(BBU) on the cloud server. In the system, the baseband signals are precoded at BBU, and then compressed before being transmitted to RRHs through capacity-limited fronthaul links which results in the compressive quantization noise. We assume the regularized zero-forcing precoding is performed with an imperfect channel state information and a compression strategy is applied at BBU. The effect of phase noise arising from nonideal local oscillators both at RRHs and users is considered. We propose an approximate expression for the downlink ergodic sum-rate of considered C-RAN utilizing large dimensional random matrix theory in the large-system regime. From simulation results, the accuracy of the approximate expression is validated, and the effect of phase noise and fronthaul compression can be analyzed theoretically based on the approximate expression.

Dynamics of Large-Truncated Mooring Systems Coupled with A Catenary Moored Semi-Submersible

With the floating structures pushing their activities to the ultra-deep water, model tests have presented a challenge due to the limitation of the existing wave basins. Therefore, the concept of truncated mooring system is implemented to replace the full depth mooring system in the model tests, which aims to have the same dynamic responses as the full depth system. The truncated mooring system plays such a significant role that extra attention should be paid to the mooring systems with large truncation factor. Three different types of large truncation factor mooring system are being employed in the simulations, including the homogenously truncated mooring system, non-homogenously truncated mooring system and simplified truncated mooring system. A catenary moored semi-submersible operating at 1000 m water depth is presented. In addition, truncated mooring systems are proposed at the truncated water depth of 200 m. In order to explore the applicability of these truncated mooring systems, numerical simulations of the platform’s surge free decay interacting with three different styles of truncated mooring systems are studied in calm water. Furthermore, the mooring-induced damping of the truncated mooring systems is simulated in the regular wave. Finally, the platform motion responses and mooring line dynamics are simulated in irregular wave. All these simulations are implemented by employing full time domain coupled dynamic analysis, and the results are compared with those of the full depth simulations in the same cases. The results show that the mooring-induced damping plays a significant role in platform motion responses, and all truncated mooring systems are suitable for model tests with appropriate truncated mooring line diameters. However, a large diameter is needed for simplified truncated mooring lines. The suggestions are given to the selection of truncated mooring system for different situations as well as to the truncated mooring design criteria.

Effect of FeS doping on large diamond synthesis in FeNi-C system

The large single-crystal diamond with FeS doping along the （111） face is synthesized from the FeNi-C system by the temperature gradient method （TGM） under high-pressure and high-temperature （HPHT）. the effects of different FeS additive content on the shape, color, and quality of diamond are investigated. It is found that the （111） face of diamond is dominated and the （100） face of diamond disappears gradually with the increase of the FeS content. At the same time, the color of the diamond crystal changes from light yellow to gray-green and even gray-yellow. The stripes and pits corrosion on the diamond surface are observed to turn worse. The effects of FeS doping on the shape and surface morphology of diamond crystal are explained by the number of hang bonds in different surfaces of diamond. It can be shown from the test results of the Fourier transform infrared （FTIR） spectrum that there exists an S element in the obtained diamond. The N element content values in different additive amounts of diamond are calculated. The XPS spectrum results demonstrate that our obtained diamond contains S elements that exist in S-C and S-C-O forms in a diamond lattice. This work contributes to the further understanding and research of FeS-doped large single-crystal diamond characterization.

Formation of overpressure system and its relationship with the distribution of large gas fields in typical foreland basins in central and western China

Based on the data of measured formation pressure, drilling fluid density of key exploration wells and calculated pressure by well logging, combined with the analysis of natural gas geological conditions, the characteristics and formation mechanisms of formation fluid overpressure systems in different foreland basins and the relationship between overpressure systems and large-scale gas accumulation are discussed.(1) The formation mechanisms of formation overpressure in different foreland basins are different. The formation mechanism of overpressure in the Kuqa foreland basin is mainly the overpressure sealing of plastic salt gypsum layer and hydrocarbon generation pressurization in deep–ultra-deep layers, that in the southern Junggar foreland basin is mainly hydrocarbon generation pressurization and under-compaction sealing, and that in the western Sichuan foreland basin is mainly hydrocarbon generation pressurization and paleo-fluid overpressure residual.(2) There are three common characteristics in foreland basins, i.e. superimposed development of multi-type overpressure and multi-layer overpressure, strong–extremely strong overpressure developed in a closed foreland thrust belt, and strong–extremely strong overpressure developed in a deep foreland uplift area.(3) There are four regional overpressure sealing and storage mechanisms, which play an important role in controlling large gas fields, such as the overpressure of plastic salt gypsum layer, the overpressure formed by hydrocarbon generation pressurization, the residual overpressure after Himalayan uplift and denudation, and the under-compaction overpressure.(4) Regional overpressure is an important guarantee for forming large gas fields, the sufficient gas source, large-scale reservoir and trap development in overpressure system are the basic conditions for forming large gas fields, and the overpressure system is conducive to forming deep to ultra-deep large gas fields.

Excavation compensation theory and supplementary technology system for large deformation disasters

Given the challenges in managing large deformation disasters in energy engineering,traffic tunnel engineering,and slope engineering,the excavation compensation theory has been proposed for large deformation disasters and the supplementary technology system is developed accordingly.This theory is based on the concept that“all destructive behaviors in tunnel engineering originate from excavation.”This paper summarizes the development of the excavation compensation theory in five aspects:the“theory,”“equipment,”“technology,”the design method with large deformation mechanics,and engineering applications.First,the calculation method for compensation force has been developed based on this theory,and a comprehensive large deformation disaster control theory system is formed.Second,a negative Poisson's ratio anchor cable with high preload,large deformation,and super energy absorption characteristics has been independently developed and applied to large deformation disaster control.An intelligent tunnel monitoring and early warning cloud platform system are established for remote monitoring and early warning system of Newton force in landslide geological hazards.Third,the double gradient advance grouting technology,the two-dimensional blasting technology,and the integrated Newton force monitoring--early warning--control technology are developed for different engineering environments.Finally,some applications of this theory in China's energy,traffic tunnels,landslide,and other field projects have been analyzed,which successfully demonstrates the capability of this theory in large deformation disaster control.