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MMC （modular multilevel converter） contains a large number of switching elements， which brings a huge computational burden to the electromagnetic transient simulation. For this problem， this paper proposes a rapid simulation method for full-bridge sub-module MMC based on bridge arm equivalent capacitance. A modeling method for arm equivalent circuit under normal working state， blocking state and full state was developed， and a simulation model was developed which can accurately simulate electromagnetic transient response of the full bridge MMC. On PSCAD/EMTDC platform， a two-terminal MMC-based DC grid test system was constructed to validate its feasibility. Additionally， the model was compared with the Thevenin equivalent model. The results confirm the accuracy and efficiency of the proposed simulation.

Orbital disorders include conditions originating from the orbital bones, surrounding tissues, and post-orbital septum. They also include systemic ailments affecting the orbit. Different clinical symptoms make up the complex range of orbital disorders. Because these disorders mostly impact the orbital area instead of the intraocular compartment, there is little diagnostic usefulness for typical ophthalmic visual tests. As such, the primary instruments for diagnosing and evaluating orbital illnesses have become ophthalmic imaging modalities, including ocular ultrasonography(B-scan), computed tomography(CT), and magnetic resonance imaging(MRI). One way to improve the precision and promptness of diagnosing orbital diseases is to standardize the functioning of widely used imaging equipment and define the radiological features of orbital abnormalities. Such programs are crucial for the care of patients with orbital disorders since they considerably reduce the number of misdiagnoses and missed diagnoses in these individuals. The underlying concepts, operational techniques, and normal and pathological imaging findings associated with common diagnostic tools for orbital illnesses are all thoroughly reviewed in this guideline. The objective is to improve primary healthcare settings' diagnostic competence in the field of orbital pathology and to standardize procedures for diagnosing orbital disorders.

Objective To evaluate the effect of ultrasonography visualization teaching in the integration course of diagnostics and ultrasonic medicine for eight-year clinical medicine program students and to provide reference for further optimization of the teaching program. Methods The study conducted a questionnaire survey with electronic questionnaire in the eight-year clinical medicine program students from Peking Union Medical College who participated in ultrasonography visualization teaching of neck and abdomen. We adopted self-control study(data from the questionnaires completed by the same student before and after the course) to compare the accuracy of each knowledge point before and after teaching to evaluate the teaching effect, and collected course satisfaction ratings and feedback from the students. Results A total of 124 eight-year medical students participated in the survey, with 107 cases eight-year clinical medicine program students in grade 2017, and 17 cases '4+4' pilot class students in grade 2019 from Peking Union Medical College. Altogether 116 valid questionnaires (the response rate was 93.5%, 116/124) were collected for neck ultrasound courses and 101 valid questionnaires (the response rate was 94.4%, 101/107) for abdominal ultrasound courses. After the teaching of neck ultrasound course, the correctness of 68.8%(11/16) and 66.7%(10/15) of the knowledge points was significantly improved for the grade of 2017 and 2019 medicine students, respectively (all P < 0.05); after the teaching of abdominal ultrasound course, the correctness of 80%(4/5) of the knowledge points was significantly improved for both the grade of 2017 and 2019 medicine students (all P < 0.05). Course satisfaction surveys showed that 99.1%(115/116)of the students were very satisfied or satisfied with the cervical ultrasound course, and 0.9%(1/116) were somewhat satisfied. As for the abdominal ultrasound course, 99.0% (100/101) of the students were very satisfied or satisfied and 1.0%(1/101) were somewhat satisfied. Twenty one medical students gave feedback on the evaluation of the course, believing that ultrasound visualization teaching improved learning initiative (52%, 11/21) and learning efficiency (43%, 9/21) and stimulated learning interest (5%, 1/21); 27 medical students made suggestions on the teaching mode, among which 'increasing teaching hours' accounted for the highest proportion (56%, 15/27), followed by 'recommending reference books' (26%, 7/27). Conclusion The ultrasonography visualization teaching improves the learning initiative and efficiency of eight-year clinical medicine program undergraduates, stimulates the learning interest, and promotes their mastery of relevant knowledge.

The DC transformers with dual active bridge （DAB） topology is characterized by zero voltage switching （ZVS） and provides the basis for realizing lossless turn-off buffer by directly paralleling buffer capacitors. First， the structure and operation control of IGCT-HDCT （IGCT-based high-capacity DC transformer） are introduced. Then， a black startup strategy based on a soft converter is proposed， which divides the start process into the extended phase shift and single phase shift startup to realize the ZVS of all devices during the black startup of IGCT-HDCT and prevent the surge current on the buffer capacitor. By analyzing the resonance process of the device after shutdown， the relationship between the phase shift and the system parameters in the extended phase shift stage is introduced， and the ZVS characteristics of the device in the single phase shift stage are verified. The transient bias current of the system is eliminated by predictive control and duty ratio design. Finally， the feasibility of the proposed control is verified by a 1.5 kV/2 MW prototype.

Objective To explore the effects of yam and cassia seed vermicelli on blood lipid metabolism and antioxidation in dyslipidemia rats. Methods Forty-eight SD rats were divided into model group (40 rats) and control group (8 rats). The rats in the model group were fed with high-fat diet for 4 weeks to establish a dyslipidemia rat model. 40 rats were randomly divided into model group, atorvastatin positive control group (10mg/kg/d), yam cassia seed vermicelli low, medium and high dose groups by random number method, with 8 rats in each group. After 5 weeks of intervention, a series of serum lipids index [total triglyceride (TG), total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C)]， liver body ratio, liver TG, TC, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), malondialdehyde (MDA) and total antioxidant capacity (T-AOC) were measured. Results Compared to the model group, TC of serum, TC and TG of liver decreased by 14.76%, 23.75% and 39.69% in the medium dose group respectively, while SOD, GSH PX and T-AOC increased by 24.09%, 26.90% and 290.24% in the low dose group, respectively (P

Objective To investigate the diagnostic value of rectal epithelial cells stability FH for the early screening of rectal cancer. Methods FH, CEA and CA19-9 were performed in 300 patients. We used pathological diagnostic results as the gold standard and electronic colonoscopy as an assistance to analyze the detection indicators of epithelial cells stability FH, CEA and CA19-9 test for screening rectal malignancy, such as sensitivity(Sen), specificity(Spe), false negative rate(missed diagnosis rate), false positive rate (the misdiagnosis rate), negative likelihood ratio (LR), positive likelihood ratio (LR+), diagnosis index (DI), Youden index, crude coincidence rate (CA), negative predictive value (PV-) and positive predictive value (PV+), etc. Results The positive rate of epithelial cell stability FH test for rectal malignant tumor was higher than those of CEA and CA19-9 (P=0.000). Among the 40 cases of rectal malignant tumor, 38 positive cases(95%) were detected by epithelial cell stability FH, 23 positive cases(57.5%) were detected by CEA, 10 positeve cases(25%) were detected by CA19-9. The sensitivity, positive likelihood ratio, diagnostic index, Youden index, negative predictive value and positive predictive value of FH were all higher than those of CEA and CA19-9, while the false negative rate and negative likelihood ratio were lower than CEA and CA19-9. Conclusion There are higher sensitivity, positive likelihood ratio, diagnostic index, Youden index, negative predictive value, positive predictive value, lower false negative rate and negative likelihood ratio of epithelial cells stability FH in rectal cancer screening.

The current study aims to examine the physical and rheological properties at the high-temperature range of 52, 58, 64, 70, 76, and 82°C, utilizing adjusted asphalt binders. Three kinds of asphalt modifiers were selected such as styrene-butadiene-styrene, ethylene vinyl acetate, and end of life tires. The selected additives were implemented with different contents ranging from 4% to 7% by the weight of neat asphalt. Various test methods have been established, such as ductility, viscosity, microscopic inspection, and dynamic shear rheometer experiments. Results proved that the percentage decrease in ductility was 93%, 91%, and 88% with regard to the adding of the end of life tires (ELTs), ethylene vinyl acetate (EVA), and styrene-butadiene-styrene (SBS) additives, respectively. Outcomes also confirmed that viscosity was boosted from 0.411 Pa.s to 1.249, 1.0986, and 0.9785 Pa.s after adding 7% of ELTs, 7% of EVA, and 7% of SBS, respectively. The rutting parameter and complex shear modulus increased after modification, indicating the excellent performance of asphalt. The conclusions confirmed that the ELTs have fewer agglomerates and have good compatibility before ageing and excellent compatibility after the ageing process. Thus, the ELTs are deemed as efficient dispersion additive for avoiding separation during the storage and handling of the asphalt binder. Lastly, ELTs were accepted as the best enhancer for their positive influence on physical and rheological characteristics, which means higher quality amended bitumen would give higher resistance to permanent deformation.

With the increase of grid-connected PV capacity, voltage regulation at point of common coupling by controlling the reactive power injected into the grid is available. This paper presents an adaptive voltage control strategy for distribution network with high proportion PV system. The PI gain of the voltage controller is automatically adjusted by the extremum seeking algorithm to dynamically respond to the changes of the network. The PI gains are updated online through the minimization of a cost function, which represents the voltage controller performance. Finally, a distribution network model of 5 MW photovoltaic power generation system is built in MATLAB / Simulink to verify the effectiveness of the proposed control strategy.

According to the available geological data and monitoring data, the completely weathered phyllite slope dilates and softens under the condition of continuous rainfall, which is then prone to instability failure. The indoor artificial rainfall test was carried out through the construction of the slope model, and the soil moisture sensor, pore water pressure sensor and matric suction sensor were used to study the variation laws of moisture content, pore water pressure and infiltration line at the back edge, slope body and the foot of the slope under continuous heavy rainfall. According to the sensor data and recorded information, with the influence of heavy rainfall over a long period of time, the water content and pore water pressure increased firstly, then decreased, and finally stabilized. The infiltration line moved from the top, the surface and the foot of the slope to the slope body, and shallow slip failure occurred in the shallow layer of the slope body.

The overall objectives of this study were to determine the most appropriate additive for improving the physical properties and the medium- and high-temperature performances (mechanical performance) of asphalt binders. Three different types of modified binders were prepared: crumb rubber modifier (CRM), polypropylene (PP), and tafpack super (TPS), which had concentrations of 2%, 3%, 3.5%, and 4% by weight of asphalt binder, for each modifier. Their physical and rheological properties were evaluated by applying various tests such as ductility, rotational viscosity, toughness, and tenacity, as well as the dynamic shear rheometer (DSR) test. As a result, the physical properties of the modified bitumen binders were compared, as were the medium- and high-temperature performances (mechanical performance), which had temperatures of 58, 64, 70, 76, 82, and 88 °C, respectively. This was how the most appropriate modifier was determined. The results demonstrated that the asphalt binder properties significantly improved by utilizing CRM followed by PP and TPS modifiers. The increase in the rutting parameter (G*/sin(δ)) after asphalt modification indicated its excellent performance at both medium- and high-temperatures. Lastly, the CRM was determined as the most preferred additive because of its positive effect on the physical properties and enhancement of the medium- and high-temperature performance (mechanical performance).

Since deformation estimation may lead to errors occurring when the camera vibrates, it is necessary to remove the image global motion before computing real bridge deformation. In this study, a combination of image motion correction algorithm and 2D image-based deformation measurement technique was utilized to address the issue of camera motion during the image data acquisition for bridge deformation measurement. Based on the proposed methodology, the image motion parameters were estimated by defining an effective sub-image in the image and using Iterative Affine Motion Estimator. Then the estimated parameters were applied to all pixels of each captured image to remove the motion effect. Finally, the corrected images were used to analyze by a 2D image-based deformation measurement technique in order to extract and measure real bridge deformation by tracking artificial or natural targets. The proposed methodology was validated by two experiments in the lab and field environments. Achieved results show the accuracy and reliability of the proposed methodology.