Riding safety prediction of a high-speed train running on transition zone under foundation settlement

Summary The length and structure of the transitional zone in the tunica media in the renal artery of adult male cats were investigated. In addition, the volume of the lumen and different layers in transitional and nontransitional zones in the right and left sides were also determined. Morphometrical, histological and stereological studies were performed on 16 renal arteries of 8 adult male cats. After perfusion and morphometrical measurement, routine tissue processing was carried out by autotechnicon. The processed tissues were embedded in paraffin and sectioned serially into 5 m thickness. The sections were stained with haematoxylin and eosin and orcein. In the morphometrical measurement, the right renal arteries were longer than the left ones with a mean value of 22.0 0.2 and 18.8 0.1 mm, respectively. Despite the fact that the right renal artery is commonly longer, the length of transitional zone was 7 mm in both renal arteries of adult male cats. The artery has a structure between muscular and elastic type at its origin with several elastic layers in the tunica media which is gradually changed to a muscular type at the distal section after 7 mm from origin of aorta. Transitional zone has an arrangement of parallel elastic fibers which become rare and fragmented towards the non-transitional zone. The volume of tunica intima, tunica media, tunica adventitia and lumen of the artery decrease from transitional zone towards the non-transitional zone and the volume of these areas in both transitional and non-transitional zones in the right renal artery is more than the left one. The volume of the lumen in transitional zone differs significantly compared to non-transitional zone, in both sides (P<0.05). Also there is a significant difference in the volume of the lumen in non-transitional zone between right and left renal arteries (P<0.05).

Improvement in lower esophageal sphincter (LES) competency after laparoscopic Nissen fundoplication (LNF) is well established, yet esophageal body physiology data are limited. We aimed to describe the impact of LNF on whole esophagus physiology using standard and novel manometric characteristics. A cohort of patients with an intact fundoplication without herniation and no postoperative dysphagia were selected and underwent esophageal manometry at one-year after surgery. Pre- and post-operative manometry files were reanalyzed using standard and novel manometric characteristics and compared. A total of 95 patients were included in this study. At 16.1 (8.7) months LNF increased LES overall and abdominal length and resting pressure (p < 0.0001). Outflow resistance (IRP) increased [5.8 (3-11) to 11.1 (9-15), p < 0.0001] with a 95th percentile of 20 mmHg in this cohort of dysphagia-free patients. Distal contractile integral (DCI) also increased [1177.0 (667-2139) to 1321.1 (783-2895), p = 0.002], yet contractile amplitude was unchanged (p = 0.158). There were direct correlations between pre- and post-operative DCI [R: 0.727 (0.62-0.81), p < 0.0001] and postoperative DCI and postoperative IRP [R: 0.347 (0.16-0.51), p = 0.0006]. Contractile front velocity [3.5 (3-4) to 3.2 (3-4), p = 0.0013] was slower, while distal latency [6.7 (6-8) to 7.4 (7-9), p < 0.0001], the interval from swallow onset to proximal smooth muscle initiation [4.0 (4-5) to 4.4 (4-5), p = 0.0002], and the interval from swallow onset to point when the peristaltic wave meets the LES [9.4 (8-10) to 10.3 (9-12), p < 0.0001] were longer. Esophageal length [21.9 (19-24) to 23.2 (21-25), p < 0.0001] and transition zone (TZ) length [2.2 (1-3) to 2.5 (1-4), p = 0.004] were longer. Bolus clearance was inversely correlated with TZ length (p = 0.0002) and time from swallow onset to proximal smooth muscle initiation (p < 0.0001). Bolus clearance and UES characteristics were unchanged (p > 0.05). Increased outflow resistance after LNF required an increased DCI. However, this increased contractile vigor was achieved through sustained, not stronger, peristaltic contractions. Increased esophageal length was associated with increased TZ and delayed initiation of smooth muscle contractions.

On the bifurcation and global energy approach in propagating plasticity

In order to better understand transition zones with a variety of structural features that affect thin varying thickness strips, 6061 aluminium alloy thin strips were flexibly rolled into different thickness ratios and transition zone lengths, using an innovative micro rolling mill. The microstructure and mechanical properties of the thin varying thickness strips produced by micro flexible rolling were systematically investigated and the mechanisms were analysed. The results indicate that a thin varying thickness strip with either a larger thickness ratio or a shorter transition zone length will present a relatively high slope of the transition zone during micro flexible rolling. After tensile tests, a thin varying thickness strip with the highest thickness ratio achieved the largest yield strength and ultimate tensile strength. In comparison, transition zone length can have a greater influence on the strain of the transition zone than on the thickness ratio because of the variation in β. The measured hardness is greater in the thinner zone than in the thicker zone. Values in the thinner zone are about 7%–21% greater than those in the thicker zone for strips with different thickness ratios due to the increased strain level which causes different degrees of work hardening.

This paper presents a method to determine the safety threshold of bridge pier settlement in high-speed railways. An analytical expression of the mapping relationship between the pier settlement and the rail deformation is derived theoretically for the double block ballastless track-bridge system. By adopting the superposition of the track random irregularity and the rail deformation caused by the pier settlement as the excitation inputs, the variations of vehicle dynamics indices with pier settlement are comparatively analyzed. Then, the safety threshold of the bridge pier settlement is obtained according to the limit of vehicle running safety and ride comfort indices of the high-speed trains. Results show that the dynamics indices of different trains have different sensitivities to the pier settlement, and the train CRH2C is the most sensitive one among all the types of Chinese high-speed trains. When passing through the bridges in common span with pier settlement at the speed of 250–350 km/h, the trains suffer the low-frequency excitations, and the vertical acceleration of car body is most sensitive to the pier settlement of all the dynamics indices. When the car body vertical acceleration just exceeds the allowable limit, the critical settlement value is 23.4 mm, which is much bigger than the pier differential settlement limit in the current code for Chinese high-speed railways.

AimsHirschsprung’s-associated enterocolitis (HAEC) is the most severe complication of Hirschsprung disease (HD), and its pathogenesis is still unknown. Length of transition zone (TZ) interposed between aganglionic and normal bowel has...

Background: The transition zone (TZ) is defined by specific histological findings in patients with Hirschsprung Disease (HSCR). HSCR treatment includes surgical removal of the aganglionic zone (AZ). During the pull-through procedure, it is critical to resect the TZ. Given the TZ’s wide histological heterogeneity, we wanted to know how extensive the histological transition zone is. Methods: A retrospective study of patients who had pull-through surgery for rectosigmoid HSCR between January 2010 and December 2020 was carried out. Demographics, length of TZ and AZ, age and symptoms upon presentation, and complications after surgery were also obtained. Results: The inclusion criteria were met by 50 patients. The mean age of all patients was 10 months (0.1–107.5 months), with a mean age at pull-through of 16.3 months (3–112 months). Thirty-one out of fifty patients (62%) received primary laparoscopic endorectal pull-through surgery (LEPT). The average TZ length of all patients was 2.6 cm (0–10 cm), and the AZ length was 9.6 cm (1–30 cm). The length of the AZ and TZ were shown to have no correlation (r² = 0.237). Conclusions: The current study found that the mean length of the TZ in individuals with rectosigmoid HSCR is less than 5 cm in most cases and has no correlation with the length of the AZ.

Measurement, Assessment, Analysis and Improvement of Transition Zones in Railway Track

Structure and length of transitional zone in the dog's external carotid artery was documented. Six normal adult male dogs were studied. The specimens were processed in the routine way by light and electron microscopy. It was established that the transitional zone with 17-mm length contains parallel and fenestrated elastic fibres. In the transitional zone, the elastic fibres in the extracellular space were greater in number than collagen fibres. However, in the non-transitional zone, the rows of smooth muscle cells were greater in number. There were more collagen fibres than elastic fibres in the extracellular space and the elastic fibres appeared to be fragmented. Therefore, the transitional zone showed a structure intermediate between those of elastic and muscular arteries. The involvement of a special structure of transitional zone in vascular disease such as atherosclerosis is suggested.

The load-deformation observation under the footing is essential for foundation design. Either experimental methods or numerical modelling generally determines this phenomenon in engineering practices. This study determined the settlement of shallow foundations on Multi-layer soil profile numerically. The settlement behavior was investigated through numerical modelling with Plaxis 2D. This study site was Jamshoro region, located in province Sindh, Pakistan. From the geotechnical investigation, the soil of Jamshoro region consists of a combination of different soils, mainly shale and limestone. This type of soil shows common challenges for the serviceable and sustainable design and construction of structural foundations. The standard penetration test conducted accompanied by other geotechnical tests on shale and limestone to determine the input parameters for the model and observe the soil profile. The Mohr-Coloumb model used for shale and linear elastic for limestone. The settlement of the foundation is attended by varying the limestone layer’s depth. In this research, the settlement reduced under the footing by increasing the thickness of the limestone layer. The study observed that stiffness of lower layer significantly reduces the settlement of shallow foundation. Therefore, the effect of lower layer should be considered for the designing of foundation on multi-layered soil.

Strong-axis stability and seismic performance of perforated core plate buckling-restrained braces

Objective Improving lighting arrangements at the highway intersections can significantly reduce the likelihood of crashes. Meanwhile, a reasonable gradient illumination scheme can increase drivers' safety by avoiding the rapid change of their pupil area when driving from an unlighted area into a lighted area. The purpose of this study is to design illumination transition zones for drivers when approaching the highway intersection, and optimize the illumination increments along the transition zones. Methods This issue is addressed in three stages. First, an indoor simulation platform is built using the UC-win/road software, and its parameters are calibrated using real intersection data collected at night. Second, the variation of pupil area under different increasing rates of illuminance near the driver's eyes (INDE) is analyzed, and a model representing the temporal change of the area in the pupil contraction stage is established. Last, an optimization model is proposed to obtain the optimal luminance increasing rates by minimizing the time needed for drivers to travel through the transition zones under different maximum illuminations and speed limits. Results The findings of this study indicate that the INDE increasing time in the transition zone remains unchanged with a determined illumination at the intersection, and the optimal transition zone length is directly proportional to the speed limit of the intersection. Therefore, the transition zone length needs to be adjusted to accommodate different speed limits: it should be extended or shortened by the same percentage as the increase or decrease of the speed limit. Conclusions It can be concluded that the illumination transition zone is necessary when the INDE of highway intersection and the speed limit exceed 8 lx and 40 km/h, respectively. The INDE increasing rate should be maintained around the optimal value, providing safe and comfortable light adaptation to drivers and preventing traffic accidents. The study will provide a scientific basis for safety implementation of lighting arrangements at highway intersections.

Two-lane rural highways attract trips between traffic generators such as residential villages or small commercial areas and are generally uninterrupted flow facilities that provide a high level of mobility with high posted speeds limits. When passing through developed areas, the posted speed limit may be lowered to encourage reduced vehicle operating speeds. No published guidelines currently exist for the design of transition zones that connect high- to low-speed operating environments on two-lane rural highways. The objective of this research was to collect operating speed and roadway characteristic data along two-lane rural highway transition zones in Pennsylvania to explore the roadway, roadside, and traffic control factors that are associated with driver speed differentials. Single- and multilevel models were estimated and compared. The posted speed limit reduction as well as a change in the paved shoulder width, total number of driveways, various advance warning signs, the transition zone length, and the presence of horizontal curves were shown to increase the expected speed reduction in transition zones in the models. Additionally, drivers entering transition zones at higher speeds were found to have greater speed reductions than drivers entering the transition zone at lower speeds.

In this paper, numerical steady-state thermal analysis and ampacity evaluation of underground power cable systems placed in PVC ducts are presented. Between the outer surface of the cable and inner surface of the duct, there are three heat transfer modes, thermal conduction, thermal natural convection and thermal radiation. A Streamline-upwind/Petrov-Galerkin (SUPG) stabilized finite element method is proposed to solve the air governing formulas including the mass conservation equation, the momentum conservation equation and the energy conservation equation in the region between the cables and the containment ducts. During the numerical thermal field analysis, the Newton-Raphson iteration method is used to solve the weak electromagnetic-thermal coupling of underground power cable systems. The radiation heat exchange between the outer surface of the cable and inner surface of the duct is solved by the Newton-Raphson iteration method too. An experiment with several holes and three cables was conducted and the test results were compared with the results of analytical method and SUPG finite element method. The comparison reveals that the convection induced heat exchange is much stronger than the conduction induced heat exchange in the air between the outer cable surface and inner duct surface and calculation accuracy of SUPG finite element method is better than the analytical method. Finally, the Newton-Raphson iteration method is used to evaluate the ampacity of power cable systems placed in PVC ducts.

Pier settlement causes deformation of bridge structures, and further distorts the track structures placed on bridge decks, which may greatly affect the service life of the tracks and safe operation of trains. This study analyzes track stresses and vehicle dynamic responses in train–track–bridge system with pier settlement and determines the pier settlement safe value for high-speed railways with China Railway Track System (CRTS) II slab tracks. First, a detailed train–track–bridge dynamic model is established based on the train–track–bridge dynamic interaction theory. Verified with field experimental results, the model is utilized to calculate the dynamic responses of the vehicle–track–bridge system with different pier settlement values. Finally, the safe value of the pier settlement in the CRTS II slab track railway line is determined according to the limit of the vehicle dynamic indicators and the structural stresses of tracks. The results show that the vertical acceleration of the car body is more sensitive to pier settlement among all the vehicle dynamic indicators. Structural stresses of tracks caused by pier settlement appear at the positions of the pier with settlement and its two adjacent piers. The effect of train loads on the track stresses is much smaller than that of the pier settlement. It is important to adopt the structural stresses of tracks as the evaluation criteria of the pier settlement safe value than the vehicle dynamic indicators. Taking the effects of the bridge pier settlement, the vehicle load, the prestress effect, and the self-weight into consideration, the pier settlement safe value for the high-speed railway lines with the CRTS II slab track is 11.5 mm.