The effect of ride experience on changing opinions toward autonomous vehicle safety

Autonomous vehicles (AVs) are a promising emerging technology that is likely to be widely deployed in the near future. People\u27s perception on AV safety is critical to the pace and success of deploying the AV technology. Existing studies found that people\u27s perceptions on emerging technologies might change as additional information was provided. To investigate this phenomenon in the AV technology context, this paper conducted real-world AV experiments and collected factors that may associate with people\u27s initial opinions without any AV riding experience and opinion change after a successful AV ride. A number of ordered probit and binary probit models considering data heterogeneity were employed to estimate the impact of these factors on people\u27s initial opinions and opinion change. The study found that people\u27s initial opinions toward AV safety are significantly associated with people\u27s age, personal income, monthly fuel cost, education experience, and previous AV experience. Further, the factors dominating people\u27s opinion change after a successful AV ride include people\u27s age, personal income, monthly fuel cost, daily commute time, driving alone indicator, willingness to pay for AV technology, and previous AV experience. These results provide important references for future implementations of the AV technology. Additionally, based on the inconsistent effects for variables across different models, suggestions for future transportation survey designs are provided

Experimental research on internal convection heat transfer of supercritical pressure CO2 in porous media

The flow and heat transfer of fluids at supercritical pressure in porous media has attracted much attention due to its extensive applications, such as supercritical water-cooled nuclear reactor, CO2 gas cooled reactor, transpiration cooling and supercritical CO2 solar thermal power generation system. There are mainly two theories to describe convection heat transfer in porous media, i.e., the local thermal equilibrium model (LTE) and the local thermal non-equilibrium model (LTNE). Compared with LTE model, the LTNE model is a more detailed model that uses two energy equations to describe heat transport in the solid and fluid. The internal heat transfer coefficient is a key parameter for LTNE model which has been studied thoroughly and many correlations have been proposed. Please download the full abstract below

Investigation of Suffusion Under Torsional Shear Conditions With CFD‐DEM

This study investigates, for the first time ever, the suffusion on gap‐graded granular soils under torsional shear conditions from a microscopic perspective. A numerical model of the hollow cylinder torsional shear test (HCTST) using the discrete element method (DEM) is first developed, where an algorithm for simulating the real inner and outer rubber membranes of the hollow cylinder apparatus (HCA) is introduced. After the validation, the computational fluid dynamics (CFD) approach is introduced for the coupling between the particle and fluid phases. Then, a series of the coupled CFD‐DEM suffusion simulations considering the rotation of the major principal stress axis (α) and intermediate principal stress ratio (b) are conducted. It is found that more fine particles are eroded in cases having smaller α and b, and the clogging phenomenon in the middle zones becomes more significant as both α and b increase. From the microscopic perspective, the specimens whose contact anisotropy principal direction is close to the fluid direction will lose more fines, and the anisotropy magnitude also plays an important role. In addition, the differences in structure and vertical connectivity of the pores in HCTST samples under various complex loading conditions cause fine particles to have different migration paths, further resulting in different fines mass loss

Evaluation of structural performance of steel-concrete joints in Hybrid Girder Bridges

The steel-concrete joint, serving as a transition zone between the steel and concrete girders, is the key component for transferring force among the hybrid girder systems. Despite the expected smooth transition of stiffness, high strength, easy fabrication, and verified static resistance, the structural performance of the steel-concrete joint under service loadings in a long-term period remains unclear. In this study, a FE model of a 1/2 steel-concrete joint from a real bridge is established to explore the long-term performance of the structure. Numerical results show that the minimal relative slip between the concrete infill and steel girder indicated the reliable capability of the steel-concrete joint, and the maximum concrete and steel stresses are 8.8 MPa and 192.8 MPa, respectively, which are far less than the material’s ultimate strength. The outcomes of this study can serve as a reference for analyzing the long-term performance of steel-concrete joints in hybrid girder bridges

CO2 Absorption by DBU-Based Protic Ionic Liquids: Basicity of Anion Dictates the Absorption Capacity and Mechanism

PILs are promising solvent systems for CO2 absorption and transformations. Although previously tremendous work has been paid to synthesize functionalized PILs to achieve a high-performance absorption, the underlying mechanisms are far less investigated and still not clear. In this work, a series of DBU-based PILs, i.e., [DBUH][X], with anions of various basicities were synthesized. The basicities of the anions were accurately measured in [DBUH][OTf] or extrapolated from the known linear correlations. The apparent kinetics as well as the capacities for CO2 absorption in these PILs were studied systematically. The results show that the absorption rate and capacity in [DBUH][X] are in proportional to the basicity of PIL, i.e., a more basic PIL leads to a faster absorption rate and a higher absorption capacity. In addition, the spectroscopic evidences and correlation analysis indicate that the capacity and mechanism of CO2 absorption in [DBUH][X] are essentially dictated by the basicities of anions of these PILs

Reduced expression of SMAD4 in gliomas correlates with progression and survival of patients

<p>Abstract</p> <p>Background</p> <p>To examine the expression of SMAD4 at gene and protein levels in glioma samples with different WHO grades and its association with survival.</p> <p>Methods</p> <p>Two hundreds fifty-two glioma specimens and 42 normal control tissues were collected. Immunochemistry assay, quantitative real-time PCR and Western blot analysis were carried out to investigate the expression of SMAD4. Kaplan-Meier method and Cox's proportional hazards model were used in survival analysis.</p> <p>Results</p> <p>Immunohistochemistry showed that SMAD4 expression was decreased in glioma. SMAD4 mRNA and protein levels were both lower in glioma compared to control on real-time PCR and Western blot analysis (both P < 0.001). In addition, its expression levels decrease from grade I to grade IV glioma according to the results of real-time PCR, immunohistochemistry analysis and Western blot. Moreover, the survival rate of SMAD4-positive patients was higher than that of SMAD4-negative patients. We further confirmed that the loss of SMAD4 was a significant and independent prognostic indicator in glioma by multivariate analysis.</p> <p>Conclusions</p> <p>Our data provides convincing evidence for the first time that the reduced expression of SMAD4 at gene and protein levels is correlated with poor outcome in patients with glioma. SMAD4 may play an inhibitive role during the development of glioma and may be a potential prognosis predictor of glioma.</p