Experimental Study of Prestressed Concrete Track Slab at Railroad Crossings

Currently, the prestressed concrete track slabs are testing installed at the field to replace the reinforced concrete track slabs at railroad crossings in Vietnam. Prestressed concrete track slabs used for 1000 mm gauge. The dimensions of each slab were designed with a length, width, and height of 2.5 m, 1.0 m, and 0.33m, respectively. This paper presents experimental measurements to analyze the behavior of the prestressed concrete track slab at railroad crossings under the action of train and truck dynamic load. Experiment measurements were implemented at the site. Eight strain gauges were mounted at three sections of the track slab to measure the deformation. HL-93 truck load and TY-7E train load were used in the test. The results show the eccentricity of the gravity center point of the prestressed wires to the centroidal axis of the transformed area. The deviation ratio between experimental and theoretical results is from 0.88% ÷ 1.25%. These results can be used to optimize the design process and limit cracks. In addition, tensile and compressive stresses in slabs are smaller than the allowable values. The results show that this track slab meets the requirements of durability and strength under the action of train and truck dynamic load

Choosing Folk Song for Children 5-6 Years Old Through Teaching Organization Music Activities in Preschool

Folk songs have the ability to have a strong impact on people's thoughts and emotions, helping us develop aesthetic abilities, thinking, intellectual, physical qualities, and good moral feelings. More importantly, it forms national consciousness and love for the homeland. Currently, teachers are aware of the importance of using folk songs for 5-6 year old children in organizing musical activities in preschools. However, preschool teachers do not know how to choose folk songs in organizing and teaching music activities, causing the results of the activities to be low. This article focuses on analyzing the current situation of choosing folk songs for 5-6 year old children through organizing and teaching musical activities, in order to form in children the goodness and beauty in folk songs. From there, children will develop a love and appreciation for Vietnamese folk songs.&nbsp

Analysis of a Prestressed Sleeper for Railway Turnout under the Effect Static Load with a Unilateral Contact Model and Support Stiffness of Existing Railway Bed of a Railway Section in Vietnam

In the process of analyzing prestressed sleepers for turnout on elastic foundations with large lengths, authors around the world often use the one-stiffness model of Winkler or the two-stiffness model of the Filonenko-Borodich and Pasternak. Railway bed stiffness is assumed to be a constant value from the design to the end of the operating process. In this study, the authors use a one-stiffness model to simulate the interaction between the prestressed sleepers for turnout and the railway bed, which helps to describe the contact and non-contact between the prestressed sleepers of turnout and the railway bed, the phenomenon that the many traditional models do not implement yet. In addition, the railway bed stiffness included in the analysis is obtained by testing at the field of a railway section in operation in Vietnam. The authors use the finite element method and combine it with the Newton iteration method. Accordingly, the analysis results of prestressed sleepers for turnout will be more consistent with actual behavior. We need to check the actual stiffness of the foundation before it is included in the analysis because the actual stiffness of the foundation gives more accurate results during analysis

Experimental Analysis on the Ultrasound-based Mixing Technique Applied to Ultra-low Sulphur Diesel and Bio-oils

Pollution in the maritime field is considered as such a serious problem that scientists, policymakers, and managers are always urged with a desire to find solutions and strategies one way or another to minimize its negative impacts on the environment and the life. Among the effective solutions, the use of fuels with limited-sulfur content or bio-based fuels has been paid much attention to due to their advantages in the use of marine diesel engines. In the current study, a type of fossil diesel fuel with ultra-low sulfur content (ULSD) was mixed with coconut oil (CO) through the ultrasonic treatment under the changes in volume fraction of as-used fuels, the correlation on viscosity selected the rate mixing between ULSD and coconut oil. After 12 minutes of ultrasound treatment, the highest stability of the ULSD-CO emulsion was achieved correspondingly to 97.8% for a mixing rate of 76%(ULSD):24%(CO) along with the distance of 85mm from the containing-vessel bottom to the ultrasound horn tip. Moreover, the spray characteristics including penetration length and a cone angle of ULSD, CO, and ULSD-CO emulsion were also examined and compared to diesel fuel. The similarity of spray characteristics to diesel fuel, containing ultra-low sulfur content and oxygen content, renewability are considered as some advantages of ULSD-CO emulsion as used for diesel engines aiming to meet the stricter requirements of IMO regulations about the strategies of environmental protection. 

Analysis of a Prestressed Sleeper for Railway Turnout under the Effect Static Load with a Unilateral Contact Model and Support Stiffness of Existing Railway Bed of a Railway Section in Vietnam

In the process of analyzing prestressed sleepers for turnout on elastic foundations with large lengths, authors around the world often use the one-stiffness model of Winkler or the two-stiffness model of the Filonenko-Borodich and Pasternak. Railway bed stiffness is assumed to be a constant value from the design to the end of the operating process. In this study, the authors use a one-stiffness model to simulate the interaction between the prestressed sleepers for turnout and the railway bed, which helps to describe the contact and non-contact between the prestressed sleepers of turnout and the railway bed, the phenomenon that the many traditional models do not implement yet. In addition, the railway bed stiffness included in the analysis is obtained by testing at the field of a railway section in operation in Vietnam. The authors use the finite element method and combine it with the Newton iteration method. Accordingly, the analysis results of prestressed sleepers for turnout will be more consistent with actual behavior. We need to check the actual stiffness of the foundation before it is included in the analysis because the actual stiffness of the foundation gives more accurate results during analysis

Experimental Study of Prestressed Concrete Track Slab at Railroad Crossings

Currently, the prestressed concrete track slabs are testing installed at the field to replace the reinforced concrete track slabs at railroad crossings in Vietnam. Prestressed concrete track slabs used for 1000 mm gauge. The dimensions of each slab were designed with a length, width, and height of 2.5 m, 1.0 m, and 0.33m, respectively. This paper presents experimental measurements to analyze the behavior of the prestressed concrete track slab at railroad crossings under the action of train and truck dynamic load. Experiment measurements were implemented at the site. Eight strain gauges were mounted at three sections of the track slab to measure the deformation. HL-93 truck load and TY-7E train load were used in the test. The results show the eccentricity of the gravity center point of the prestressed wires to the centroidal axis of the transformed area. The deviation ratio between experimental and theoretical results is from 0.88% ÷ 1.25%. These results can be used to optimize the design process and limit cracks. In addition, tensile and compressive stresses in slabs are smaller than the allowable values. The results show that this track slab meets the requirements of durability and strength under the action of train and truck dynamic load

Evaluation of genetic diversity of Vietnamese dogs based on mitochondrial DNA hypervariable-1 region

Haplogroup E were detected with high frequency in the population of Phu Quoc ridgeback dogs suggesting that this Vietnamese valuable dog breed originated from domestic dogs harbouring haplogroup E from Vietnam’s mainland or from East Asia where the presence of haplogroup E was reported. Evaluation of the genetic diversity of the Vietnam’s mainland dogs and haplogroup Escreening would support us in tracking out the origin of Phu Quoc ridgeback dog

A Study on Derailment at Railway Turnout Using the Multi-body Dynamics Simulation

In this study, the locomotive and the turnout were simulated with three-dimensional models. The purpose of this study is prediction the derailment phenomenon of the locomotive running on the turnout in Vietnam. Multi-body simulations were implemented by SIMPACK software to determine the derailment coefficient, the wheel unloading factor, and the lateral force. The interaction between the locomotive and the track structure at turnout was considered unified. The derailment coefficient, the wheel unloading factor, and the lateral force were calculated for locomotive-D19E at turnout (tg0.15) for 1000 mm gauge according to QCVN 18:2011/BGTVT, EN 14363:2016, and TCVN 8784:2011. The derailment coefficient, the wheel unloading factor, and the lateral force for the locomotive at max speed V=27.8 km/h are 0.94, 0.61, and 67.46 kN, respectively. These results show that the locomotive will not derail when it passes the turnout at a speed V 27.8 km/h

Behavior of monolithic prestressed concrete slab track at highway-railway grade crossings

Highway-railway grade crossings are an important part of the transportation system. It allows two types of vehicles to operate in the same areas. Researchers have previously studied the grade crossings, but research on the monolithic prestressed concrete slab (PSCS) track at grade crossings for 1,000mm gauge is limited. At present, there are many types of grade crossing structures that are using in Vietnam. However, these structures still have many disadvantages in the operation process. A new structure type of grade crossing for PSCS is proposed to apply for the 1,000 mm gauge to overcome the main disadvantages of existing structural types. This paper presents test production and experimental measurements to analyze the behavior of PSCS. Test samples of monolithic PSCS were produced in factory. Measurement experiments were conducted in the laboratory. The results of the manufacturing and testing process presented in this paper show that this structure completely meets the criteria of stability and durability under the effect of test loads

Improving Pareto Front Learning via Multi-Sample Hypernetworks

Pareto Front Learning (PFL) was recently introduced as an effective approach to obtain a mapping function from a given trade-off vector to a solution on the Pareto front, which solves the multi-objective optimization (MOO) problem. Due to the inherent trade-off between conflicting objectives, PFL offers a flexible approach in many scenarios in which the decision makers can not specify the preference of one Pareto solution over another, and must switch between them depending on the situation. However, existing PFL methods ignore the relationship between the solutions during the optimization process, which hinders the quality of the obtained front. To overcome this issue, we propose a novel PFL framework namely PHN-HVI, which employs a hypernetwork to generate multiple solutions from a set of diverse trade-off preferences and enhance the quality of the Pareto front by maximizing the Hypervolume indicator defined by these solutions. The experimental results on several MOO machine learning tasks show that the proposed framework significantly outperforms the baselines in producing the trade-off Pareto front.Comment: Accepted to AAAI-2