With the wide application of sculptured surface in modern manufacturing industry, precision requirement of machining parts with sculptured surface has been increasing. After a part is processed and ...inspected, the measured data can be obtained. Yet, machining error reduction is still an important topic. This paper provides a novel methodology to compensate machining error of sculptured surface by using on-machine measurement (OMM) data to alter the position and orientation of theoretical CAD model. The approach does not need establishment of complex reconstruction model and modification of original tool path, so it is easy to be developed to engineering application. This method can be implemented in three steps. First, the representation of error evaluation for sculptured surface is given as the basis of error compensation. Second, the mirror method is applied to determine the optimal matching parameters of the theoretical surface. Then the reconstructed CAD model of the machined surface can be directly generated by modifying the position and orientation of theoretical surface so that the tool path is regenerated based on the reconstruction of the CAD model. Meanwhile, the influence of overcutting after compensation is considered. Eventually, experiments are performed on five-axis machine tools to prove its effectiveness. Results show that the method can effectively improve the machining accuracy of sculptured surface.
Objectives
Based on the current clinical routine, we aimed to develop a novel deep learning model to distinguish coronavirus disease 2019 (COVID-19) pneumonia from other types of pneumonia and ...validate it with a real-world dataset (RWD).
Methods
A total of 563 chest CT scans of 380 patients (227/380 were diagnosed with COVID-19 pneumonia) from 5 hospitals were collected to train our deep learning (DL) model. Lung regions were extracted by U-net, then transformed and fed to pre-trained ResNet-50-based IDANNet (Identification and Analysis of New covid-19 Net) to produce a diagnostic probability. Fivefold cross-validation was employed to validate the application of our model. Another 318 scans of 316 patients (243/316 were diagnosed with COVID-19 pneumonia) from 2 other hospitals were enrolled prospectively as the RWDs to testify our DL model’s performance and compared it with that from 3 experienced radiologists.
Results
A three-dimensional DL model was successfully established. The diagnostic threshold to differentiate COVID-19 and non-COVID-19 pneumonia was 0.685 with an AUC of 0.906 (95% CI: 0.886–0.913) in the internal validation group. In the RWD cohort, our model achieved an AUC of 0.868 (95% CI: 0.851–0.876) with the sensitivity of 0.811 and the specificity of 0.822, non-inferior to the performance of 3 experienced radiologists, suggesting promising clinical practical usage.
Conclusions
The established DL model was able to achieve accurate identification of COVID-19 pneumonia from other suspected ones in the real-world situation, which could become a reliable tool in clinical routine.
Key Points
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In an internal validation set, our DL model achieved the best performance to differentiate COVID-19 from non-COVID-19 pneumonia with a sensitivity of 0.836, a specificity of 0.800, and an AUC of 0.906 (95% CI: 0.886–0.913) when the threshold was set at 0.685
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In the prospective RWD cohort, our DL diagnostic model achieved a sensitivity of 0.811, a specificity of 0.822, and AUC of 0.868 (95% CI: 0.851–0.876), non-inferior to the performance of 3 experienced radiologists
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The attention heatmaps were fully generated by the model without additional manual annotation and the attention regions were highly aligned with the ROIs acquired by human radiologists for diagnosis
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Double-sided microlens arrays (DSMLAs) include combinations of two single-sided MLAs to overcome positioning errors and greatly improve light transmissivity compared to other types of lenses. ...Precision glass molding (PGM) is used to fabricate DSMLAs, but controlling alignment errors during this process is challenging. In this paper, a mold assembly was manufactured with a novel combination of materials to improve the alignment accuracy of mold cores during PGM by using the nonlinear thermal expansion characteristics of the various materials to improve the DSMLA alignment accuracy. By establishing a mathematical model of the DSMLA alignment error and a thermal expansion model of the mold-sleeve pair, the relationship between the maximum alignment error of the DSMLA and the mold-sleeve gap was determined. This research provides a method to optimize the mold-sleeve gap and minimize the alignment error of the DSMLA. The measured DSMLA alignment error was 10.56 μm, which is similar to the predicted maximum alignment error. Optical measurements showed that the uniformity of the homogenized beam spot was 97.81%, and the effective homogeneous area accounted for 91.66% of the total area. This proposed method provides a novel strategy to improve the performance of DSMLAs.
In this paper, the pain point that cold chain transportation urgently needs for an efficient disinfection method is pointed out. Thus, this work aims at solving the problems and improving the ...disinfection efficiency in cold chain transportation. While Ultraviolet-C (UVC) irradiation is an effective method by which to kill viruses, it is difficult to apply the commonly used UVC-LED disinfection light source to ice-covered cold chain transportation due to its uneven light field distribution. Thus, the light field regulation of UVC-LED disinfection for cold chain transportation is studied. A UVC-LED chip with a wavelength of 275 nm was used as a light source, and parallel light was obtained by collimating lenses. Then, microlens array homogenization technology was used to shape the UVC light into a uniform light spot, with an energy space uniformity rate of 96.4%. Moreover, a simulation was conducted to compare the effects of the ice layer on the absorption of UVC light. Finally, an experiment was carried out to verify that the disinfection efficiency can be increased nearly by 30% with the proposed system by disinfecting E. coli (Escherichia coli), and the results indicate that the proposed system is an effective disinfection solution during cold chain transportation.
Machining efficiency and accuracy are subjected to higher requirements due to the increasingly widespread application of sculptured surface parts in the fields of aerospace, transportation, and ...energy. However, the influence of geometric error, tool deflection, and other factors decreases the quality and reliability of CNC machined workpiece. Error compensation is a popular and effective way to improve the machining accuracy of the workpiece. A novel multi-stage error compensation methodology that combines model-based and data-driven approaches is proposed, which realizes the closed-loop quality control process of the sculptured surface by five-axis flank milling. The global process consists of two special stages. First, the compensated machining of stage I is completed by a flexible mirror compensation method after establishing the tool deflection prediction model, which is the major factor causing the geometric error of the machined part. Subsequently, based on the on-machine measurement (OMM) data, the surface is automatically reconstructed by mirror points in 3D software and the toolpath for stage II compensated machining is generated. Finally, the verification experiment on the five-axis machine tool demonstrates that the methodology introduced in this research can effectively enhance the machining accuracy of the workpiece.
As the demand for slim liquid crystal displays (LCDs) continues to rise in the lighting and visual display fields, the edge-lit backlight structure has received significant attention. However, the ...edge-lit backlight structure cannot function properly without a light guide plate (LGP) system. This study proposes a novel LGP system employing a laser as the light source and utilizing optical fiber as a waveguide. The design transmits a laser beam into the LGP through an optical fiber, adds microstructure and reflective surfaces, and optimizes the layout of the microstructure. Under the condition that a single point light source is used as the incident light source of the system, the illumination uniformity of the light output surface is finally realized to be as high as 95.8 %, and the light transmission efficiency is as high as 79.7 %. Next, the light output performance of the LGP was measured in the case of single-point light entry on the short side of the strip LGP, and the difference between the test results and the simulation data was within 5 %. The system adopts the fiber optic transmission method of electro-optical separation, which has certain application prospects in the fields of underwater detection, decorative lighting and urban landscape.
•The innovative fiber-conducted laser light guide plate system is proposed for the first time.•Achieved the conversion of single-point light source input into area light output.•Through simulation and optimization by LightTools software, the system achieves an impressive illumination uniformity.•A physical system was constructed to validate the simulated illuminance of the LGP surface.•Established spatial independence between the light source and the LGP.
Coarctation of the aorta (CoA) in adolescents and adults is often complicated by other cardiac or aortic problems and may carry additional surgical difficulties. Limited studies have reported the ...surgical outcomes of CoA repair in this particular patient population. We reviewed our contemporary experience of open surgical management of CoA in adolescents and adults.
From 2008 to 2016, a total of 60 adolescents and adults (mean age, 32 years) underwent CoA repair at our centre. Of this cohort, 43 patients only underwent CoA repair (isolated group), while the remaining 17 underwent other concomitant cardiac procedures (concomitant group). Ascending-to-descending aortic bypass was the preferred repair technique in the concomitant group. Aortic valve replacement and a Bentall/David procedure were the two most frequently combined procedures.
There were no in-hospital deaths in the isolated group compared with three in the concomitant group (0% vs 17.6%, P = 0.029). The median intensive care unit stay (1 vs 2 days, P <0.01) and postoperative hospital stay (6 vs 9 days, P <0.01) were significantly longer in the concomitant group. Postoperative respiratory failure occurred more frequently in the concomitant group (0% vs 17.6%, P = 0.029). The isolated group had better overall survival during follow-up ( P = 0.037). The 5-year overall survival rate was 98% in the isolated group and 82% in the concomitant group.
Surgical management of coarctation in adolescents and adults can achieve similar satisfactory outcomes as their neonatal counterparts, but the complexity of the concomitant procedures is a risk factor for this particular patient population.
Abstract
OBJECTIVES
Sinus of Valsalva aneurysms (SVAs) are rare and are often complicated by aortic insufficiency (AI). Treating AI is important for achieving good long-term results in patients with ...SVA. Here, we have summarized our experience with the surgical management of patients with SVA with concomitant AI.
METHODS
Patients who were diagnosed with SVA and underwent surgical treatment between January 2008 and May 2016 were included. Clinical characteristics, including age, gender, SVA anatomy and concurrent anomalies, were analysed. The surgical strategies, intraoperative results and early and late outcomes were evaluated.
RESULTS
A total of 178 patients (age 37.4 ± 13.1 years, 114 men) were identified. Eighty-seven (48.9%) patients had at least 2+ AI preoperatively. Patients with AI had a significant higher incidence of right coronary SVA with concomitant ventricular septal defects (80.5% vs 54.9%, P < 0.001). Concurrent aortic valve surgery was performed in 70 patients with 63 valve replacements and 7 valve repairs. The other 17 patients underwent SVA repair only. The mean follow-up time was 44.4 ± 33.8 months. During the follow-up, no patients who underwent valve replacement experienced perivalvular leakage, whereas 7 patients who underwent aortic valve repair had trivial-to-mild AI and 3 of the 17 patients who underwent SVA repair only presented with moderate AI.
CONCLUSIONS
Various surgical techniques can be utilized to manage concomitant AI without compromising short-term outcomes. Valve replacement yields good long-term results. According to our experience, valve repair, especially valve-sparing procedures performed by experienced surgeons, could be an acceptable option when managing concomitant AI in young patients.
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