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In this paper, eleven high-strength steel tube confined self-stressing concrete (HSTCSC) short columns were tested to study their strengthening mechanism and axial compression performance. The effects of different material strengths, cross-section types, and hollow ratios on the axial mechanical properties of the HSTCSC short columns were investigated using the finite element analysis method. Experimental results highlighted that the HSTCSC short columns presented the waist drum-type failure mode significantly, with a higher axial load-bearing capacity and deformation performance, and possess a large safety reserve. It was also found that the axial compression property of the HSTCSC short column could be improved significantly due to the joint action of the micro-expansion of the self-stressing concrete and the hoop constraint of the high-strength steel tube. Moreover, the circular cross-section HSTCSC short columns were found to result in better mechanical performance after yielding of the high-strength steel tubes, especially entering the strengthening section. Under the condition of equal steel content ratio and cross-section area, the single-layer circular HSTCSC short columns were found to have the largest load-bearing capacities after yielding the high-strength steel tubes, followed by the double-layer circular HSTCSC short columns, and then the double-layer square HSTCSC short columns. The hollow rate of the cross-section could also decrease the load-bearing capacity of the HSTCSC short column with both circular and square sections, although increasing the hollow rate could save material and reduce the weight of the structure. The finite element analysis results showed that the proposed finite element model could be employed to simulate the compressive behavior of HSTCSC short columns with high calculation accuracy.

Numerical research is conducted to investigate the effects of plasma boundary shape on the tearing mode triggering explosive bursts in toroidal tokamak plasmas. In this work, m/n = 2/1 mode is responsible for the triggering of the explosive burst. Plasma boundary shape can be adjusted via the adjustment of the parameters triangularity δ and elongation κ. The investigations are conducted both under low β (close to zero) and under finite β regimes. In the low β regime, triangularity and elongation both have stabilizing effect on the explosive burst and the stabilizing effect of elongation is stronger. Under a large elongation (κ = 2.0), the elongation effect can evidently enhance the stabilizing effect in a positive triangularity regime, but barely affects the stabilizing effect in a negative triangularity regime. In the finite β regime, the explosive burst is delayed in comparison with that in the low β regime. Similar to the low β cases, the effects of triangularity and elongation both are stabilizing. Under a large elongation (κ = 2.0), the elongation effect can evidently enhance the stabilizing effect on the explosive burst in a positive triangularity regime, but impair the stabilizing effect in a negative triangularity regime. The explosive burst disappears in the large triangularity case (δ = 0.5), indicating that the explosive burst can be effectively prevented in experiments via carefully adjusting plasma boundary shape. Moreover, strong magnetic stochasticity appears in the negative triangularity case during the nonlinear phase.

Background Coronary distensibility index (CDI), as an early predictor of cardiovascular diseases, has the potential to complement coronary computed tomography angiography (cCTA)-derived fractional flow reserve (CT-FFR) for predicting major adverse cardiac events (MACEs). Thus, the prognostic value of CT-FFR combined with CDI for MACEs is worth exploring. Methods Patients with a moderate or severe single left anterior descending coronary artery stenosis were included and underwent FFR and CDI analysis based on cCTA, followed up at least 1 year, and recorded MACEs. Multivariate logistic regression analysis was performed to determine independent predictors of MACEs. The area under of receiver operating characteristic (ROC) curve was used to evaluated evaluate the diagnostic performance of CT-FFR, CDI, and a combination of the two. Results All the vessel-specific data were from LAD. 150 patients were analysed. 55 (37%) patients experienced MACEs during follow-up. Patients with CT-FFR ≤ 0.8 had higher percentage of MACEs compared with CT-FFR > 0.8 (56.3% vs.7.3%, p p p = 0.025), triglyceride (p = 0.015), CT-FFR ≤ 0.80 (p = 0.038), and CDI (p p = 0.0002). Conclusion Our study provides initial evidence that combining CDI with CT-FFR shows incremental discriminatory power for MACEs over CT-FFR alone, independent of clinical risk factors. Diabetes and triglyceride are also associated with MACEs.

Objective This paper proposes a new photoacoustic computed tomography (PACT) imaging system employing dual ultrasonic transducers with different frequencies. When imaging complex biological tissues, photoacoustic (PA) signals with multiple frequencies are produced simultaneously; however, due to the limited bandwidth of a single-frequency transducer, the received PA signals with specific frequencies may be missing, leading to a low imaging quality. Methods In contrast to our previous work, the proposed system has a compact volume as well as specific selection of the detection center frequency of the transducer, which can provide a comprehensive range for the detection of PA signals. In this study, a series of numerical simulation and phantom experiments were performed to validate the efficacy of the developed PACT system. Results The images generated by our system combined the advantages of both high resolution and ideal brightness/contrast. Conclusion The interchangeability of transducers with different frequencies provides potential for clinical deployment under the circumstance where a single frequency transducer cannot perform well.

Evaluating the impacts of human activity on river runoff has important implications for regional water resource management. Here, we used seven tree-ring width chronologies to establish a regional mean tree-ring width chronology from the northern mountain of Delingha, Qaidam Basin. We conducted the correlation, moving correlation and regression analysis of regional mean tree-ring width chronology with runoff data from Bayin River gauge station. Then, we stimulated the June runoff of Bayin River from 1956 to 2002. The results showed that the highest correlation coefficient was found for June runoff (评估人类活动对径流的影响,对区域水资源开发管理有借鉴和指导意义。利用柴达木盆地北部山区7个祁连圆柏树轮宽度数据,建立区域平均树轮宽度年表。通过对区域平均树轮宽度年表与巴音河水文站径流量进行相关、滑动相关和回归分析,模拟了巴音河1956—2002年6月天然径流量变化,进而分析出人类活动对径流量的影响。结果表明: 树轮平均年表与6月径流量的相关性最强(

Large burst activity, identified as toroidal Alfvén eigenmode (TAE) avalanche, occurs frequently in neutral-beam heated plasmas in National Spherical Torus Experiment (NSTX). Based on the typical experimental observation of TAE avalanche on NSTX, a self-consistent nonlinear multiple wave-number (k ∥ ≃ n/R, where n toroidal mode-number and R major radius) simulation associated with TAE avalanches is performed using the experimental parameters and profiles before the occurrence of TAE avalanche as the M3D-K input. The wave–wave nonlinear coupling among different modes and the resonant interaction between different modes and energetic-ions during TAE avalanches are identified in the nonlinear multiple wave-number simulations. The resonance overlap during the TAE avalanche is clearly observed in the simulation. It is found that the effective wave–wave coupling and a sufficiently strong drive are two important ingredients for the onset of TAE avalanches. TAE avalanche is considered to be a strongly nonlinear process and it is always accompanied by the simultaneous rapid frequency-chirping and large amplitude bursting of multiple modes and significant energetic-ion losses. The experimental phenomenon is observed on NSTX and is qualitatively reproduced by the simulation results in this work. These findings indicate that the onset of avalanche is triggered by nonlinearity of the system, and are also conducive to understanding the underlying mechanism of avalanche transport of energetic particles in the future burning plasmas, such as International Thermonuclear Experiment Reactor.