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Background: Analyzing fundus images with deep learning techniques is promising for screening systematic diseases. However, the quality of the rapidly increasing number of studies was variable and lacked systematic evaluation. Objective: To systematically review all the articles that aimed to predict systemic parameters and conditions using fundus image and deep learning, assessing their performance, and providing suggestions that would enable translation into clinical practice. Methods: Two major electronic databases (MEDLINE and EMBASE) were searched until August 22, 2023, with keywords ‘deep learning’ and ‘fundus’. Studies using deep learning and fundus images to predict systematic parameters were included, and assessed in four aspects: study characteristics, transparent reporting, risk of bias, and clinical availability. Transparent reporting was assessed by the TRIPOD statement, while the risk of bias was assessed by PROBAST. Results: 4969 articles were identified through systematic research. Thirty-one articles were included in the review. A variety of vascular and non-vascular diseases can be predicted by fundus images, including diabetes and related diseases (19%), sex (22%) and age (19%). Most of the studies focused on developed countries. The models’ reporting was insufficient in determining sample size and missing data treatment according to the TRIPOD. Full access to datasets and code was also under-reported. 1/31(3.2%) study was classified as having a low risk of bias overall, whereas 30/31(96.8%) were classified as having a high risk of bias according to the PROBAST. 5/31(16.1%) of studies used prospective external validation cohorts. Only two (6.4%) described the study’s calibration. The number of publications by year increased significantly from 2018 to 2023. However, only two models (6.5%) were applied to the device, and no model has been applied in clinical. Conclusion: Deep learning fundus images have shown great potential in predicting systematic conditions in clinical situations. Further work needs to be done to improve the methodology and clinical application.

Lorlatinib was found to have activity in ALK-positive NSCLC in a global phase 1 and 2 study. We report an ongoing phase 2 study in Chinese patients with ALK-positive advanced or metastatic NSCLC.

The temperature field of the wet clutch is an important factor that influences the vehicle transmission performance. In order to predict and prolong the service life of the wet clutch, a test bench is built, and an accelerated life test is carried out based on the actual working conditions. Then, according to the variation of the friction coefficient and the maximum radial temperature difference, the sliding temperature field is analyzed in different periods. By introducing four evaluation indexes, a temperature field evaluation system is established and verified. With the help of this evaluation system, the temperature fields during running-in and unstable stages are compared, and the thermal failure mechanism of the friction disc is analyzed. In the stable stage, the influence of rotational speed, oil pressure and lubricant flow on the temperature field are investigated. The results of this study can guide the design and control of the friction components in the wet clutch.

An enhanced Cu-based friction material was prepared by the powder metallurgy techniques and proposed for use in the dry clutch system. The friction characteristics and wear rate of this friction material sliding against 65Mn steel are obtained using Universal Material Tester-5. The friction pairs were subjected to two operating variables, which are sliding speed and temperature. The effect of these variables during the engagement process of the friction pairs is investigated. Knowing the normal applied force and dimension of the clutch disc, the dynamic friction coefficient was translated to friction torque capacity with time. It was found that instability can be excited at low operational conditions when the resulting friction coefficient is high. At 25 ℃, the dynamic friction torque oscillates with time likewise at 400 ℃. Generally, a more stable friction torque is obtained when the sliding speed is varied compared to varying the temperatures. Moreover, the influence of the operating temperatures and sliding speeds on thermal buckling and thermoelastic instability of the friction disc is the second consideration in this work. The onset of thermoelastic instability occurs when the sliding speed exceeded 200 r/min and the results for the growth rate of hot spots were found to agree well with the critical speed of the system. Also, thermal buckling was highly dependent on the temperature difference between the inner and outer radius of the friction disc.

Studies have shown that reinforced paper-based friction material with 600 µm carbon fiber length possesses a high dynamic friction coefficient but is subjected to abrasive wear during sliding contact. This work is devoted to further investigate the effect of operating variables on this friction material subjected to high operating conditions. A pin-on-disc test was carried out to determine the tribological behavior of this friction material sliding against 65Mn steel. The friction and wear rate results from measurements were discussed. The highest friction value of about 0.3 was obtained by varying the applied load at 120 N while the lowest friction value close to 0.02 was obtained when the sliding speed was 0.026 m/s. Increasing the sliding speed above 0.30 m/s caused constant temperature (175 °C) to fluctuate due to high friction heat generation on the sliding surface. The highest wear rate was 1.42 × 10−15m3/Nm by varying the sliding speed at 1.31 m/s. In contrast, the lowest wear rate was 2.1 × 10−16m3/Nm when the temperature was at 400 °C.

This paper presents an investigation of the hot judder behavior in a multi-disc clutch with the uneven contact pressure and the initial temperature taken into account. Considering the actual structure of clutch, the pressure function is achieved to describe the uneven contact pressure distribution due to the circlip constraint. Moreover, the pin-on-disc test is conducted to obtain the formula of the coefficient of friction with the contact pressure, surface temperature, and rotating speed involved. The thermal and dynamic models are established and coupled to evaluate the hot judder behavior. The results demonstrate that the uneven contact pressure has a slight influence on the clutch hot judder, but it expands the radial temperature difference on the friction surface; meanwhile, the friction torque generated on the friction surface closer to the circlip is larger. Although the increase of initial temperature can shorten the clutch engagement time, the clutch hot judder will be shriller, as verified in the SAE#2 bench test. Furthermore, in order to reduce the clutch hot judder, the circlip should be optimized to smooth the radial contact pressure, and the advanced thermal management method should be applied to strengthen the clutch heat dissipation.

Proposing an appropriate control strategy is an effective and practical way to address the overheat problems of the wet multi-plate clutches in Direct Shift Gearbox under the long-time creeping condition. To do so, the temperature variation of the wet multi-plate clutch is investigated first by establishing a thermal resistance model for the gearbox cooling system. To calculate the generated heat flux and predict the clutch temperature precisely, the friction torque model is optimized by introducing an improved friction coefficient, which is related to the pressure, the relative speed and the temperature, before being demonstrated experimentally using a full scale powertrain test. After that, the verified heat transfer model and the reasonable friction torque model are employed by the vehicle powertrain model to construct a comprehensive co-simulation model for the Direct Shift Gearbox vehicle, capable of simulating the dynamic responses and predicting the temperature variations of two clutches. A creeping control strategy is then proposed and, to evaluate the vehicle performance, the safety temperature (250°C) is particularly adopted as an important metric. From the variations in torque and speed obtained from the simulation results, the vehicle can track the desired speed (1.5 km/h) satisfactorily, with only 3% fluctuation, and have good longitudinal dynamic performance (8.5 m/s3). But above all, during the entire 174 s creeping process, the temperature of two clutches is always under the safety value (250°C), which demonstrates the effectiveness of the proposed control strategy in avoiding the thermal failures of clutches.

During the torque phase, appropriate coordination between two clutches is of vital importance to the dual-clutch transmission so that a high-quality shift is achieved without clutch interaction and engine flare, because a poor-quality shift definitely extends the shift time and increases the friction work. Concerning this problem, two different power flow conditions during the torque phase are discussed in detail, after investigation of the dual-clutch transmission downshift process and the design of an H∞robust controller for the inertia phase. The results obtained indicate that, if two clutches are slipping simultaneously during the torque phase, either power interruption or power circulation occurs. Thus, by optimizing the relationship between the two clutches, a novel control strategy is proposed for the dual-clutch transmission so that the downshift process is accomplished with only one slipping clutch, in order to obtain the highest system efficiency. The system model was established on the MATLAB/Simulink platform and used to study the variations in the torque and the speed output in response to different control strategies. The simulation results show that, with the smooth inertia phase guaranteed by the robust controller, the proposed control strategy not only can avoid power interruption or power circulation during the torque phase but also can shorten the shift time (from 1.1 s to 0.8 s) and reduce the jerk level (from 6.8 m/s3to 5.7 m/s3) effectively, in comparison with the conventional control strategy. Finally, to validate the effectiveness of the proposed control strategy, bench tests on a dual-clutch transmission were carried out, and the test data obtained show good agreement with the simulation results.

The phenomenon of non-uniform pressure distribution among multi-disc friction pairs is investigated focusing on the effect produced by the circlip using a theoretical model and a 3D FEM model. A temperature field computational model of the discs is established based on the non-uniform pressure distribution. Sliding experiments are conducted to investigate the influence of circlip on non-uniform pressure distribution among the discs in the multi-disc clutches, and the temperature simulation results are verified by the experimental results. The obtained results show that the concentrated circlip constraint leads to the non-uniform pressure distribution in both the radial and axial directions, and in turn affects the temperature fields of discs. Unlike uniform pressure, the non-uniform pressure caused by the concentrated circlip constraint will lead to different temperature fields in different discs. Furthermore, the highest temperature and the maximum radial temperature difference both occur on the disc next to the circlip. Besides, the ratio coefficient of temperatures can effectively represent the pressure transfer coefficient among discs.

This paper presents an investigation of the hot judder phenomenon of multidisc clutches, which takes place during the engagement process. Depending on the results of finite element analysis, a pressure distribution function is defined and a contact pressure equation is established to demonstrate the non-uniformity of the contact pressure distribution on the friction interfaces due to frictional heat. The relationship between the coefficient of friction and the temperature is analyzed. A 4 degrees of freedom power-train model is developed to evaluate the clutch judder behavior. The paper indicates that the clutch judder is influenced by the non-uniformity of the interface contact pressure distribution, which is excited by frictionally induced thermal load. The non-uniform contact pressure distributions along the radial direction have a slight influence on the clutch judder, while the uneven contact pressure distributions along the circumference contribute to the judder substantially. Furthermore, the results in this work can be used to study the operation instability and the thermal failure of clutches.

This paper deals with the effects of friction material properties on thermoelastic instability (TEI) and the associated dominant deformation mode. Both analytical and finite element models are constructed for determining the variation of the critical speed and the dominant TEI mode. Some important factors, e.g. the nonconductive friction material as well as the symmetric and anti-symmetric TEI deformation modes, are investigated. It has been found that the dominant TEI deformation mode is strongly dependent on the properties of frictional material. The results show that the symmetric mode can be dominant in the condition when the friction material has either a sufficiently large elastic modulus or a sufficiently small thermal conductivity. These research findings are useful for vehicle clutch and brake designs.

A theoretical model of friction plate is established by using Resal theorem, and the inertia resistance of the friction plate is obtained from this theoretical model. Focusing on the bias phenomenon in friction pairs, a new model is investigated for analyzing the bias state under low speed difference considering about the gyro effect. As for the gap shrinkage under high speed difference, the negative pressure contraction model for the friction pairs is built by analyzing the oil film and the pressure between plates. Based on that, the influences of the inertia resistance of the friction plates for these two models are also discussed. Afterwards the gap dynamic change between friction pairs is investigated in the whole variation range of the relative speed. Finally, an improved model, considering the influence of the gap dynamic change between friction pairs, is proposed to simulate the drag torque. The results obtained from the simulation and test data indicate that, under the same lubrication condition, the drag torque in the wet multi-disk clutch increases at first and then decreases and finally increases with the rise of the rotational speed difference. Furthermore, the main factors influencing the drag torque are the bias of plates in the low speed difference (0[?]1000r/min) and the gap shrinkage in the medium and high speed difference (>1000r/min) respectively. From the comparison between test data and the simulation results obtained from the improved model, the average relative error is only 6.34% at medium and high speed difference (>1000r/min), which can greatly improve the accuracy for the estimation of the drag torque in wet multi-disk clutch.