Thermal Analysis of a Novel Oil Cooled Piston Using a Fluid-Solid Interaction Method

Thermal load has a vital influence on the normal operation and service life of diesel engines.In this study,the thermal load and oil-cooling effect on diesel engine pistons were investigated by means of computational fluid dynamics.In particular,the flow and heat transfer characteristics of the cooling gallery were determined during the oscillation of the piston.Moreover,the temperature field distribution of the piston with and without the cooling gallery were compared.The results revealed that the cooling gallery has a prominent effect on reducing the thermal load on the piston crown and piston lands.To fully understand the oscillating heat transfer effect related to the cooling gallery and verify the accuracy of the calculation,the numerical results were also compared with temperature values experimentally measured at key positions of the piston.The measurements were found to be consistent with the calculation results within an acceptable error range,which proves the rationality and accuracy of the mathematical and numerical models used.

Breeding of Yujingyou 50,a New Late Hybrid Rice Combination with Good Quality

Yujingyou 50 is a new high-quality late indica hybrid rice combination selected by Institute of Grain and Oil Crops,Nanchang Academy of Agricultural Sciences and Hunan Zhonglang seed Industry Co.,Ltd.The combination matured 3 d earlier than Tianyouzhan.It has the characteristics of moderate plant type,broad and long flag leaves,general tillering ability,colorless palea tips,large panicles with many grains,high seed setting rate,average 1000-grain weight,good color change at maturity,and rice quality reaching grade 2 of ministry standard.It was approved by the Jiangxi Provincial Crop Variety Approval Committee on March 18,2021.This paper introduced the breeding process,characteristics,cultivation techniques and key points of seed production of this variety.

Comparative Test of New Late Indica Hybrid Rice Combinations with Good Quality

[Objectives]This study was conducted to screen rice varieties suitable for planting in Nanchang City with high quality,high yield,good yield,and strong disease and stress resistance.[Methods]Seven new late indica hybrid rice combinations with good quality bred in Jiangxi Province in recent years and seven new late indica hybrid rice combinations with good quality bred by Nanchang Academy of Agricultural Sciences were introduced,and compared with Tianyouhuazhan as a control.[Results]The rice quality and taste of the tested combinations were better than those of the control.Among the tested combinations,Yuliangyoufuxiangzhan,Xintaiyousizhan,Yuxiangliangyou No.8 and Guangheyou 33 had good stress resistance,high yield and good rice quality.[Conclusions]This study provides a theoretical basis for the selection and breeding of new rice varieties in Nanchang City.

Modeling conflict risk with real-time traffic data for road safety assessment:a copula-based joint approach

This study proposes a conflict-based traffic safety assessment method by associating conflict frequency and severity with shorttermtraffic characteristics. Instead of analysing historical crash data, this study employs microscopic trajectory data to quantify therelationship between conflict risk and traffic characteristics. The time-to-collision (TTC) index is used to detect conflicts, and a severityindex (SI) is proposed on the basis of time-integrated TTC. With SI, the k-means algorithm is applied to classify the conflict severitylevel. Then the severity of regional conflict risk is split to three levels. Zero truncated Poisson regression and ordered logit regressionmethods are employed to estimate the effects of short-term traffic characteristics on conflict frequency and severity, respectively.Furthermore, the copula-based joint modelling method is applied to explore the potential non-linear dependency of conflict riskoutcomes. A total of 18 copula models are tested to select the optimal ones. The HighD dataset from Germany is utilized to examinethe proposed framework. Both between-lane and within-lane factors are considered. Results show that the correlations betweentraffic characteristics and conflict risk are significant, and the dependency of conflict outcomes varies among different severity levels.The difference of speed variation between lanes significantly influences the conflict frequency and severity simultaneously. Findingsindicate that the proposed method is practicable to assess real-time traffic safety within a specific region by using short-term (30-second time interval) traffic characteristics. This study also contributes to develop targeted proactive safety strategies by evaluatingroad safety based on conflict risk, and considering different severity levels.