Mechanical Properties of Polyurethane Mixture and Load Response Behaviour of Polyurethane Composite Pavement.

Finite element numerical simulation calculation of pavement structure load response is widely applied; however, there is still a lack of research on the polyurethane (PU) mixture composite pavement load response. The mechanical characteristics of PU mixture composite pavement are not well understood, and there is a lack of research on typical pavement structures of PU mixtures, which limits their application in pavement structures. Therefore, herein, the mechanical properties of PU mixtures are analysed using the dynamic modulus test, uniaxial penetration test, and fatigue test. Further, the finite element theory calculation method is used to realize the load response calculation of orthogonal design composite pavement structure. The results show that PU mixtures exhibit more obvious elastic characteristics and have good shear resistance, fatigue stability, and temperature stability, and can be used as shear and anti-fatigue layers. The structure of '4 cm SMA-13 + 5 cm PUM-20 + 6 cm PUM-25 + semi-rigid base' is recommended for the PU mixture composite structure. In comparison to typical asphalt pavement, the analysis shows that except for shear stress, temperature has little effect on the load response of PU composite pavement structures, while high temperatures lead to a significant increase in the load response of typical asphalt pavement structures. The PU composite pavement can bear greater loads and has a reduced thickness of its surface layer by about 3 cm in comparison to conventional pavement. The results of this study provide theoretical support for the design of PU mixture pavement structures and promote the popularization and application of PU mixture pavement.

Why Do Drivers' Collision Avoidance Maneuvers Tend to Cause SUVs to Sideslip or Rollover on Horizontal Curve and Grade Combinations?-An Analysis of the Causes Based on a Modified Multibody Dynamics Model.

The extent to which drivers' collision avoidance maneuvers affect the safety margins of sideslip and rollover is not captured by road geometric design theory. To quantify the effects of drivers' collision avoidance maneuvers on the safety margins of sport utility vehicles (SUVs) on horizontal curve and grade combinations, a modified 8-degree-of-freedom multibody model based on SUVs was developed. The model was then used to calculate the design safety margins of sideslip and rollover for steady states and the actual safety margins for collision avoidance maneuvers. Subsequently, the design safety margin reduction rate (the difference between the design and actual safety margins divided by the design safety margin) was calculated and used to assess the safety margins. The results showed that the safety margins of SUVs were significantly reduced by braking, lane changing, and lane changing with braking. The marginal effects indicated that the greater the deceleration and the shorter the lane change duration, the greater the effect on the safety margins, particularly the sideslip safety margin. Furthermore, when the SUV was driven at 80 km·h-1 on grades with a horizontal curve radius of 270 m and 400 m, the sideslip safety margin with emergency braking (deceleration over -4.5 m·s-2) was reduced by 71% and 21%, and the rollover safety margin was reduced by 11% and 5%, respectively. Under these conditions, an emergency lane change (lane change duration less than 2 s) caused the SUV to sideslip and reduced the rollover safety margin by 47% (curve radius 270 m) and 45% (curve radius 400 m). Therefore, drivers' collision avoidance maneuvers are a factor that cannot be neglected in alignment design.

Study on the Applicability and Modification of the Design Hourly Volume on Rural Expressways Considering Holiday Traffic Polarization.

The design hourly volume (DHV) of traffic based on the 30th highest hourly volume (30 HV) of the year has been widely applied in expressway design in various countries to balance the benefit and economy of expressway engineering. However, this design method has barely changed since it was first adopted in China, which may be contrary to the rapidly changing traffic macroenvironment. In this study, annual hourly traffic volume (HV) data pertaining to expressways in East China, Southwest China and Northwest China were collected. Based on the descending order of the obtained HV and HV factor data, the distribution patterns of the traffic demand throughout the year and peak hours were analyzed. The distribution characteristics of the HV, typicality of 30 HV and applicability of the DHV factor were investigated. It was found that severe polarization occurred in the HV distribution in China. The actual 30 HV factor is more than 0.5 times the recommended value in the specification. Continued use of the current DHV would result in more than 200 h of inefficient travel time, 5.7 times more than expected, with the DHV factor is currently no longer applicable in China. Furthermore, the annual 30 HV value loses its typical status. Depending on the level of local economic development, using 10 HV factor or 80 HV factor as the new DHV factor can better alleviate the congestion problem. This study determines the reasons for the widespread congestion issues in China from the perspective of expressway design, which is beneficial to adjust the basis of expressway design in China.

Five-year disease-free survival of Epstein-Barr virus-associated locoregionally advanced undifferentiated nasopharyngeal carcinoma patients treated with chemo-radiotherapy: a case report.

BACKGROUND: Nasopharyngeal carcinoma (NPC) is a tumor caused by epithelial cells covering the surface of the nasopharynx. NPC only accounted for less than 1% of all cancers diagnosed worldwide. However, the global incidence rates are highest in southern China. We report a case of local advanced undifferentiated NPC [specifically, vesicular nucleus cell carcinoma (VNCC) of NPC]. Long-term disease-free survival (DFS) of a patient with stage IVA NPC is reported. CASE DESCRIPTION: A 42-year-old male presented with a 4-month history of rhinorrhea and a lump in the left neck. The positron emission tomography (PET) showed local invasion to the surrounding tissues, specifically, the tumor invaded the brain. The pathological diagnosis was VNCC, the Epstein-Barr virus (EBV) was positive in tumor tissues by in situ hybridization. and the clinical diagnosis was stage IVA of NPC. The patient was treated with induction chemotherapy (IC) with gemcitabine and cisplatin (GP) followed by cisplatin/radiotherapy. The tumor lesions complete response (CR) after concurrent chemo-radiotherapy (CCRT). CONCLUSIONS: To date, the DFS time has been more than 5 years. IC with GP followed by CCRT should be the first choice of treatment for patients with locoregionally advanced NPC. In recent years, more and more studies have shown the efficacy of immunotherapy in treating recurrent or metastatic NPC patients, especially in patients or are programmed death-ligand 1 (PD-L1)-positive or have a high tumor mutation burden. In the future, immunotherapy may become a standard treatment in clinic and bring longer survival to patients.

Effect Analysis of Soil Type and Silt Content on Silt-Based Foamed Concrete with Different Density.

This paper investigates the influence of silt content and coarse particle content on the mechanical and physical properties of foamed concrete, including compressive and flexural strength, modulus of elasticity, water absorption, drying shrinkage, and air-void structure. Four types of silt with different coarse particle contents were obtained by soil mixing. The results showed that high density, low silt content, and high coarse particle content can provide better mechanical properties. High silt content and high coarse particle content would lead to lower drying shrinkage. Silt content was the main factor affecting the pore distribution of foamed concrete, and higher coarse particle content could optimize the air-void structure. Meanwhile, the change in air-void structure can accordingly affect the water absorption of foamed concrete. Results showed that, at the same density and silt content, higher coarse particle content can optimize the physical and mechanical properties of foamed concrete.