Summary
A large crack detection dataset of 2446 manually labeled images is established to cover a wide range of noise and to evaluate the performance of end‐to‐end deep convolutional networks in ...detecting cracking. Five state‐of‐the‐art end‐to‐end deep computer vision architectures for semantic segmentation are trained and evaluated, including Fully Convolutional Network (FCN), Global Convolutional Network (GCN), Pyramid Scene Parsing Network (PSPNet), UPerNet, and DeepLabv3+. For the backbones, the VGG, ResNet, and DenseNet are adopted. Based on the comparison of test set metrics, DeepLabv3+ with the ResNet101 backbone achieved the highest IoU of 0.6298, the highest recall of 0.6834, and the highest F1 score of 0.7732. The influence of database choice and image noise on crack detection performance is reported. Based on the comparison of predicted images, UperNet with ResNet101 backbone shows the highest performance for images with shadings, while DeepLabv3+ with ResNet101 backbone shows the best performance for images with blemishes. The research outcome can provide reference for the application of fast and accurate detection of cracks in civil engineering.
Famine provides quasi-experimental conditions for testing the hypothesis of "programming" health effects by poor nutrition in early life. It remains uncertain whether early life exposure to famine ...increases the risk of hypertension in adulthood. There is a lack of data on the relative impact of exposure to famine during fetal development versus infancy (<2 years postnatal). We sought to assess the impact of exposure to the 1959-1961 Chinese Great Famine (the largest in human history) during fetal development and infancy on the risks of hypertension, short stature and obesity in adulthood.
We conducted a retrospective cohort study of 12,065 adults (46-53 years of age) born 1957-1964 in the Zhongshan and Nanhai municipalities of Guangdong province, China. Adjusting for socio-demographic and lifestyle characteristics, as compared to subjects who were unexposed to famine, the risk of hypertension was not significantly elevated in subjects exposed to famine during fetal development only overall, but was 1.36-fold higher in those exposed during the first trimester of pregnancy only adjusted odds ratio (OR) 1.36 (95% confidence intervals 1.03-1.79), 1.83-fold higher in those exposed during infancy only adjusted OR 1.83 (1.61-2.08), and 1.31-fold higher in those exposed during both fetal development and infancy adjusted OR 1.31 (1.14-1.51). Exposure to famine during infancy increased the risk of short stature. Early life exposure to famine did not increase the risk of obesity.
Exposure to the Chinese Great Famine during the first trimester of pregnancy only, or during infancy only, or during both fetal development and infancy increased the risk of hypertension in adulthood, suggesting an important role of changes in exposure to famine during fetal development and from prenatal to early postnatal life in developmental "programming" cardiovascular disease risk.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
AbstractA new triaxial constitutive model Tsinghua University Concrete Three-dimensional (THUC3) of concrete was developed for high-fidelity finite-element (FE) simulation of composite plate shear ...wall–concrete encased (C-PSW/CE), which has been adopted as the lateral force-resisting system in numerous ultrahigh-rise buildings. In this formulation, a uniaxial constitutive model of concrete was introduced. The following five key features of concrete were included in the proposed model: compressive softening of unconfined and confined concrete, tension softening, pinching effect, shear softening, and strength degradation due to principal tensile strain. A triaxial constitutive law was also illustrated based on a fixed crack assumption. By assuming that the stress of the concrete can be decoupled in the crack coordinate system upon initial cracking, the triaxial constitutive law was assembled from the aforementioned uniaxial stress–strain relations. A new formulation is proposed to achieve strain decomposition and stress assembly in three-dimensional stress space. The numerical implementation of the stress update algorithm in an ABAQUS user material (UMAT) subroutine was illustrated. The modeling scheme and material constitutive laws of reinforcing bars, steel plates, and studs were also introduced. Subsequently, the developed triaxial constitutive model was validated at the material level by simulating the cyclic behavior of concrete and reinforced concrete (RC) specimens. The developed FE model showed good accuracy in simulating the hysteretic behavior, ultimate capacity, and residual strain in cyclic tensile loading. Two flexural critical C-PSW/CE tests, Specimens C30-5 and C40-5, were also completed and reported in this research, and 18 shear critical C-PSW/CE tests were collected from the existing literature. These tests were simulated to further validate the developed model at the structural level. Comparisons indicated that the proposed model showed a reasonable level of accuracy in terms of ultimate capacity, energy consumption, and failure mode. In addition, the modeling of studs by a nonlinear connector element is recommended based on comparisons between the test and FE results. The current AISC provisions for shear capacity of C-PSW/CE specimens were also evaluated relative to the computational and experimental results.
AbstractFour shear-critical RC shear walls were tested under a tension-bending-shear load to replicate seismic behavior of the bottom shear wall in high-rise buildings. The axial tension ratio ranged ...from 0 to 0.5 and the aspect ratio was 1.06. The shear compression failure mode was observed for each specimen, characterized by the formation of an inclined crack at 45° and direct strut action. The shear displacement was a dominant deformation component throughout the loading history. When the axial tension force increased from 0 to 1,293 kN, the ultimate drift ratio increased from 0.90% to 2.38%, while shear capacity linearly decreased from 1,507 to 895 kN. The load–displacement curve showed a significant pinching effect and strength degradation effect. In addition, this paper reports an innovative experimental method to obtain shear resistance of transverse reinforcement (Vs) based on the plasticity theory and strain measuring result. Test results using this method show that not all horizontal distributed rebar yield simultaneously at the ultimate capacity. The US code-specified shear strength contribution of horizontal distributed rebar was found to be unsafe for each test specimen. Finally, a database of RC shear walls subject to combined tension-bending-shear load was established to evaluate shear strength formulas in design codes. The comparison showed the Chinese code predicted spuriously higher tension-shear capacity, while the US code predicted conservative capacity. Based on the developed database, a simplified design formula is proposed with adequate safety concerns and accuracy.
Fatigue after stroke is common and has a negative impact on rehabilitation and survival. However, its pathogenesis and contributing factors remain unclear. The purpose of this study was to identify ...factors influencing the occurrence of fatigue after first-ever ischemic stroke in acute phase.
We examined 265 consecutive patients with first-ever ischemic stroke during acute phase (within 2 weeks) in two tertiary stroke care hospitals in Henan, China. We documented patients' demographic and clinical characteristics through face-to-face interviews using structured questionnaires and reviews of medical records. Post-stroke fatigue was defined as a score of ≥4 using the Fatigue Severity Scale. Multivariate logistic regression was used to examine post-stroke fatigue in relation to socio-demographic, lifestyle, clinical characteristics and family function.
About 40% first-ever ischemic stroke patients experienced post-stroke fatigue in acute phase. Post-stroke fatigue was associated with lack of exercise before stroke (adjusted odds ratio 4.01, 95% CI 1.95-8.24), family dysfunction (2.63, 1.20-5.80), depression (2.39, 1.02-5.58), the presence of pre-stroke fatigue (4.89, 2.13-11.21), use of sedative medications (4.14, 1.58-10.88), coronary heart disease (3.38, 1.46-7.79) and more severe Modified Rankin Scale (2.55, 1.65-3.95).
The causes of post-stroke fatigue are multifaceted. More physical exercise, improving family function, reducing depression and appropriate use of sedative medications may be helpful in preventing post-stroke fatigue.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
AbstractA novel biaxial finite-element (FE) model is proposed and validated by a total of 32 reinforced concrete (RC) shear walls with aspect ratio below 1.5. First, a biaxial concrete model package, ...which was previously developed in ABAQUS software for RC panel tests, is adopted to evaluate its accuracy of simulating RC shear walls. The FE modeling scheme, the biaxial FE model of concrete before and after initial cracking, and the uniaxial FE model of concrete are illustrated. The developed model considers the following five significant features including the concrete compressive softening, tension softening, concrete shear softening, pinching effect, and strength reduction because of lateral cracking. Second, the traditional rebar model without buckling and the longitudinal rebar model considering buckling are also illustrated. Third, the discrete Fréchet distance is adopted to quantify the relative error between FE simulation results and test results. Subsequently, the constitutive model in ABAQUS simulates a total of 32 RC shear walls under axial and lateral forces. The simulated RC shear walls cover a wide range of parameters, including aspect ratio, rebar orientation, reinforcement, and section shape. The FE simulation results are compared with test results including the force versus lateral deformation curves, load-shear displacement curves, and failure modes. According to the comparison, the developed constitutive model shows high accuracy for RC shear walls with aspect ratio below 1.5, including the replication of pinching effect and residual capacity. The developed model overestimated the initial stiffness of some test specimens, which may be attributed to the omission of concrete cracking induced by shrinkage. In general, the overall accuracy of the developed constitutive model is validated.
Background
Patients with multimorbidity often experience treatment burden as a result of fragmented, specialist‐driven healthcare. The ‘family doctor team' is an emerging service model in China to ...address the increasing need for high‐quality routine primary care.
Objective
This study aimed to explore the extent to which treatment burden was associated with healthcare needs and patients' experiences.
Methods
Multisite surveys were conducted in primary care facilities in Guangdong province, southern China. Interviewer‐administered questionnaires were used to collect data from patients (N = 2160) who had ≥2 clinically diagnosed long‐term conditions (multimorbidity) and had ≥1 clinical encounter in the past 12 months since enrolment registration with the family doctor team. Patients' experiences and treatment burden were measured using a previously validated Chinese version of the Primary Care Assessment Tool (PCAT) and the Treatment Burden Questionnaire, respectively.
Results
The mean age of the patients was 61.4 years, and slightly over half were females. Patients who had a family doctor team as the primary source of care reported significantly higher PCAT scores (mean difference 7.2 points, p < .001) and lower treatment burden scores (mean difference −6.4 points, p < .001) when compared to those who often bypassed primary care. Greater healthcare needs were significantly correlated with increased treatment burden (β‐coefficient 1.965, p < .001), whilst better patients' experiences were associated with lower treatment burden (β‐coefficient −0.252, p < .001) after adjusting for confounders.
Conclusion
The inverse association between patients' experiences and treatment burden supports the importance of primary care in managing patients with multimorbidity.
Patient Contribution
Primary care service users were involved in the instrument development and data collection.
Ultra-thick offshore steel, known for its high strength, high toughness, and corrosion resistance, is commonly used in marine platforms and ship components. However, when offshore steel is in service ...for an extended period under conditions of high pressure, extreme cold, and high-frequency impact loads, the weld joints are prone to fatigue failure or even fractures. Addressing these issues, this study designed a narrow-gap laser wire filling welding process and successfully welded a 100-mm new type of ultra-thick offshore steel. Using finite element simulation, EBSD testing, SEM analysis, and impact experiments, this study investigates the weld's microstructure, impact toughness, and fracture mechanisms. The research found that at -80 °C, the welded joint exhibited good impact toughness (>80 J), with the impact absorption energy on the surface of the weld being 217.7 J, similar to that of the base material (225.3 J), and the fracture mechanism was primarily a ductile fracture. The impact absorption energy in the core of the weld was 103.7 J, with the fracture mechanism mainly being a brittle fracture. The EBSD results indicated that due to the influence of the welding thermal cycle and the cooling effect of the narrow-gap process, the grains gradually coarsened from the surface of the welded plate to the core of the weld, which was the main reason for the decreased impact toughness at the joint core. This study demonstrates the feasibility of using narrow-gap laser wire filling welding for 100-mm new type ultra-thick offshore steel and provides a new approach for the joining of ultra-thick steel plates.
AbstractSteel plate reinforced concrete (SPRC) composite shear walls, which are composed of steel columns embedded in boundary elements and an embedded steel plate in the wall web, have been used in ...super-high-rise buildings. When subjected to rare earthquake loads, combined tension-bending-shear actions are often generated in the shear walls of super-high-rise buildings because of the increasing demand for a greater height–width ratio. Based on quasistatic tests on seven SPRC shear walls under tension-bending loads, the seismic behavior of SPRC shear walls with various steel-content ratios and axial tension ratios was investigated. The failure mode, strength and displacement capacity, stiffness degradation, shear deformation, damping coefficient, strain, and cracking of each test specimen are presented in detail. The failure mode is divided into tension-bending failure, anchorage failure, and torsional buckling failure according to the test results. The strength, stiffness, and ductility of the SPRC shear walls were significantly reduced with an increase in the axial tension ratio. The fiber beam-column finite-element (FE) model was simulated using MSC.MARC software. A comparison showed that the FE model predicted the load-displacement relationship, stiffness degradation, and ultimate capacity with a reasonable level of accuracy. Based on the test results, a design method is proposed for predicting the ultimate strength of the SPRC shear walls under tension-bending combined loads, and recommendations for improved anchorage design are proposed.
PDF
