z. liu

To investigate the success rate and quality of automatic airway segmentation using ultra-low dose CT (ULD-CT) images of different reconstruction algorithms.

Fifty two children who underwent chest ULD-CT were divided into three groups for analysis based on age: group A (n=13, age, 1-2years), group B (n=19, age, 3-6years) and group C (n=20, age, 7-13years). CT images were reconstructed with filtered back-projection (FBP), 50% adaptive statistical iterative reconstruction-Veo (50%ASIR-V), 100%ASIR-V, deep learning image reconstruction (DLIR) with low (DLIR-L), medium (DLIR-M), and high (DLIR-H) strengths. Subjective image quality was evaluated using a 5-point scale. CT value, noise, and sharpness of the trachea were measured. The VCAR software was used to automatically segment airways and reported the total volume. Segmentation success rates were recorded, and segmentation images were subjectively evaluated using a 6-point scale.

The average tracheal diameters were 8.53±1.88mm, 10.69±1.65mm, and 12.72±1.97mm, respectively for groups A, B, and C. The segmentation success rate depended on patient groups: group C reached 100%, while group A decreased significantly. In group A, 100%ASIR-V had the lowest rate at 7.69%, while DLIR-M and DLIR-H significantly improved the rate to 38.64% (P=0.03). For the segmented images, DLIR-H provided the lowest noise and highest subjective score while FBP images had the highest noise and 100%ASIR-V had the lowest overall score (P<0.05). There was no significant difference in the total airway volume among the six reconstructions.

The airway segmentation success rate in ULD-CT for children depends on the tracheal size. DLIR improves airway segmentation success rate and image quality.

Traditional cross-media retrieval methods mainly focus on coarse-grained data that reflect global characteristics, while ignoring the fine-grained descriptions of local details. Meanwhile, traditional methods cannot accurately describe the correlations between the anchor and the irrelevant data. To solve the problems mentioned above, this paper proposes to fuse coarse-grained and fine-grained features and a multi-margin triplet loss on the basis of a dual-framework. 1) Framework I: a multi grained data fusion framework based on Deep Belief Network, and 2) Framework II: a multi-modality data fusion framework based on the multi-margin triplet loss function. In Framework I, the coarse grained and fine-grained features fused by the joint Restricted Boltzmann Machine are input into Framework II. In Framework II, we innovatively propose the multi-margin triplet loss. The data, which belong to different modalities and semantic categories, are stepped away from the anchor in a multi-margin way. Experimental results show that the proposed method achieves better cross-media retrieval performance than other methods with different datasets. Furthermore, the ablation experiments verify that our proposed multi-grained fusion strategy and the multi-margin triplet loss function are effective.

Spurred by the world’s attention to pollution emissions from commercial aero-engines, the International Civil Aviation Organization (ICAO) has made more stringent emission regulations for civil aircraft engines, especially the NOx emission.This paper develops a Five-Point lean direct injection (LDI) combustor with three swirler schemes to reduce the emissions of commercial aircraft engines. The flowfield of the combustor is studied numerically. Moreover, the combustion efficiency and gaseous emissions in different inlet conditions and fuel ratios of the main stage (α) are studied experimentally. The corresponding results reveal that, under a fuel-air ratio (FAR) between 0.0130 and 0.0283 and an α value between 30% and 60%, the combustion efficiency is 99.18%, 98.83%, and 99.03% when the pilot stage works alone, and 99.69%, 99.23%, and 99.75% when the pilot and main stage work simultaneously. Furthermore, the experimental results suggest that the NOx emission decreases as α increases, demonstrating that the convergent swirler has a tremendous advantage in reducing NOx emissions over Venturi.

To explore the effect of kilovolt (kV) selection based on body mass index (BMI) on reducing the radiation dose of radiofrequency ablation (RFA) in liver tumours under computed tomography (CT) guidance.

This study retrospectively reviewed CT-guided RFA of liver tumours performed between 1 January 2019 and 31 December 2019. The radiation dose received by the patients was recorded after the planning, execution and surgery. The RFA protocol for liver tumours was subsequently modified according to the patients’ BMI. Changes in tube voltage and tube current were recorded for the RFA protocol based on BMI. The image quality and overall operator satisfaction were recorded for each case based on the BMI-modified protocol. The radiation dose received by the patients was also recorded, and the degree of dose reduction adjusted based on BMI was calculated.

The results showed that the mean (± SD) overall CT dose index (CTDI) of CT-guided RFA was 12.83 ± 3.78 mGy. Following protocol modification, the mean CTDI decreased to 3.84 ± 2.24 mGy, a 70.07% reduction overall. The image quality was slightly lower compared with before the modification, but the image quality in both stages met the needs of CT-guided RFA for liver tumours. Electrode needle display and operator confidence satisfaction showed no significant difference between the groups (P > 0.05).

Modification of the BMI-based kV protocol could significantly reduce the radiation dose received by patients during CT-guided ablation of liver tumours. Furthermore, the image quality was not significantly compromised.

Radiation therapy inevitably causes certain radiation damage to normal cells such as human vascular endothelial cells (HVECs), in addition to eliminating tumor cells. This article discusses the influence of miR-711 on the survival and apoptosis of human umbilical vein endothelial cells (HUVECs) after X-ray radiation.

The expression of miR-711 and v-maf musculoaponeurotic fibrosarcoma oncogene family protein G (MAFG) was detected by real-time quantitative polymerase chain reaction (RT-qPCR), and the content of vascular cell adhesion molecule 1 (VCAM-1) in serum was detected by Enzyme-linked immunosorbent assay (ELISA). The survival and apoptosis of HUVECs after X-ray irradiation were analyzed by functional experiments, and validation of MAFG as a miR-711 target was done by dual-luciferase reporter assay.

In the serum of prostate cancer patients miR-711 was up-regulated, while MAFG was down-regulated compared to the control group. After X-ray radiation intervention, miR-711 levels were increased, in contrast, MAFG levels decreased with a concomitant increase in VCAM-1 expression.. The percentage of survival level of HUVECs decreased gradually and the apoptosis rate of HUVECs increased as the dosage of X-ray radiation increased. Notably, after 2Gy X-ray radiation, the miR-711 inhibitor increased the survival rate of HUVECs while reducing the apoptosis rate, in contrast to the miR-711 mimic decreased the survival rate of HUVECs and increased the apoptosis. Besides, luciferase activity assay demonstrated the targeting of miR-711 to MAFG.

The inhibition of miR-711 might abrogate the function of X-ray irradiation on the survival and apoptosis of HUVECs.

This article studies the aerodynamic performance of a novel bypass shock-induced thrust vector nozzle. An arc-shaped bypass is innovatively designed to optimize nozzle performance and equips a variable shrinkage part. The nozzle performance is investigated numerically under diverse shrinkage area ratios. Computational results indicate that both geometry and friction choking have important effects on the nozzle performance. Normally, in the case of without any bypass shrinkage, the flow choking occurs at the bypass outlet. Very small bypass shrinkage is unable to change the flow choking location. The bypass geometry choking comes up at its throat as the shrinkage area ratio of the bypass reaches 0.06. According to computational results, the vectoring angle diminishes with the increasing shrinkage area ratio of the bypass, thrust force ratio, thrust efficiency, specific impulse ratio, and coefficient of discharge increase. As the NPR enlarges, the deflection angle and thrust efficiency decrease, and the thrust force ratio increases.

To identify the best time-interval for dual-source coronary computed tomography angiography (CCTA) with bolus tracking automatic trigger technique.

120 patients were randomly divided into four groups (A, B, C and D), with 30 patients in each group. Monitoring was begun 10 seconds after injection, and the monitoring time-intervals for groups A, B, C and D were 1.14, 1.47, 2.00 and 3.00 seconds, respectively. CCTA acquisition was triggered as the monitored concentration in the region of interest (ROI) exceeded 100 HU. The monitoring times, CT and dose length product (DLP) values of the four groups were compared statistically. The quality of recorded CCTA images was evaluated objectively, and the image quality of blood vessel segments was accessed subjectively.

there were no statistically significant differences in objective evaluations between the four groups (P>0.05). Subjective evaluation results showed no statistically significant differences between groups A (1.879±0.042), B (1.876±0.043) and C (1.881±0.052). Group D showed the highest subjective score (2.923±0.069), which was significantly different from groups A, B, and C (P<0.01). The monitoring times for groups A, B, C and D were 4.78±2.37, 3.76±1.39, 2.77±0.99 and 2.38±0.64, respectively; and the DLP values were 4.13±2.22, 2.18±0.80, 1.50±0.51 and 1.48±0.43 mGy·cm, respectively. DLP increases with increased monitoring times.

When performing dual-source CCTA, a monitoring time-interval of 2 seconds with trigger scanning technique is the best choice, since it effectively reduces the radiation dose while providing satisfactory images.

The flow fields around vehicle drag reduction devices are three-dimensional, complicated, and unsteady. Meanwhile, the small scale of the drag reduction device brings more challenges to the simulation. An Improved Delayed Detached Eddy Simulation (IDDES) was applied to study the effect of two types of drag reduction device. First, the flow field of an Ahmed body at a 25° slant was simulated in detail using IDDES and verified by experiment data. Afterwards, the flow field structures of adding-on vortex generators (VGs) and riblets on the rear and slant surface of the Ahmed body were studied. The simulation results of the velocity, pressure and vortex structure on the controlled case are presented by comparing with the baseline model to illustrate the drag reduction mechanism. The two drag-reduction devices had different flow mechanisms and significantly affected the development of the separation vortex near the rear and slanted surface. A maximum drag reduction of 6.21% could be achieved using VGs on the rear surface. Finally, four combinations of those two devices were investigated. The results demonstrated that suitable combinations can further decrease the aerodynamic drag, and an 8.62% drag reduction is achieved.

In order to solve the problem of insufficient thrust measurement accuracy of aeroengine indoor testbed, the thrust calibration experiment technology is studied. Form two aspects of engine static calibration and dynamic calibration, the mechanism of thrust calibration is comprehensively analyzed form the perspective of testbed and engine, and a complete set of operable test specifications is formed. The technical difficulties of engine consistency, inlet temperature deviation and non-standard weather are solved, and the accuracy of thrust transmission process is ensured. The test scheme of indoor test bed calibration is given, and the corresponding ideas and requirements are given according to the test conditions, test bench, calibration engine, test process and result analysis, to ensure the accuracy of calibration results.

Energy conservation and emission reduction has become increasingly significant for automobiles under the severe energy situation. Hybrid electric vehicle (HEV) technology is one of the most promising solutions. In this study, structures and features of current mainstream hybrid powertrains are classified and illustrated respectively. 30 representative HEV models have been acquired by going through HEV list in the bulletin released by Ministry of Industry and Information Technology of China (MIIT), and the effectiveness of fuel consumption reduction data are also acquired. Based on the basic cost data of EPA, a cost analysis is applied to estimate the incremental cost of those 30 HEVs in China respectively. Further, comparative analysis and comprehensive assessment of cost, and cost effectiveness fuel consumption reduction are processed for each hybrid system. Assessments of the application and the future developing direction for each hybrid system are made.