Metabarcoding of fecal DNA reveals the broad and flexible diet of a globally endangered bird

Knowing the diet of endangered wild animals is a prerequisite for species-specific conservation and habitat management.The Sichuan partridge Arborophila rufipectus is a globally endangered Galliformes species endemic to the mountains of southwest China.Existing information on the diet of this species is biased and fragmented owing to traditional observation methods.Little is known about their dietary composition or how they respond to temporal variations in food resources throughout the year.In this study,a dietary analysis was performed on 6o fecal samples using DNA Metabarcoding of invertebrates and plants to determine the primary animal and plant components of the diet across 3 critical periods of adult life history(breeding,postbreeding wandering,and overwintering).Preys from the dipteran order,followed by the lepidopteran and ara-neaen spp.,were the predominant,animal-derived foods.Symplocos,Rubus,Celastrus,Holboellia,and Actinidia spp.supply a large abundance of fruits and seeds for this omnivorous bird.Substantial temporal dietary changes among the 3 periods and a general shift toward lower dietary diversity during the breeding season were observed,suggesting that the Sichuan partridge can adjust their diet according to the availability of food resources and their own needs.Characterizing the composition and seasonal changes in Sichuan partridge diets informs the habitat management of native flora(the plant taxa that can generate berries and seeds,such as Symplocos,Rubus,Celastrus,and Holboellia,which are likely of conservation interest)to achieve full life-cycle conservation.

Analysis of wheel-rail adhesion redundancy considering the thirdbody medium on the rail surface

Purpose–In response to the problem of insufficient traction/braking adhesion force caused by the existence of the third-body medium on the rail surface,this study aims to analyze the utilization of wheel-rail adhesion coefficient under different medium conditions and propose relevant measures for reasonable and optimized utilization of adhesion to ensure the traction/braking performance and operation safety of trains.Design/methodology/approach–Based on the PLS-160 wheel-rail adhesion simulation test rig,the study investigates the variation patterns of maximum utilized adhesion characteristics on the rail surface under different conditions of small creepage and large slip.Through statistical analysis of multiple sets of experimental data,the statistical distribution patterns of maximum utilized adhesion on the rail surface are obtained,and a method for analyzing wheel-rail adhesion redundancy based on normal distribution is proposed.The study analyzes the utilization of traction/braking adhesion,as well as adhesion redundancy,for different medium under small creepage and large slip conditions.Based on these findings,relevant measures for the reasonable and optimized utilization of adhesion are derived.Findings–When the third-body medium exists on the rail surface,the train should adopt the low-level service braking to avoid the braking skidding by extending the braking distance.Compared with the current adhesion control strategy of small creepage,adopting appropriate strategies to control the train’s adhesion coefficient near the second peak point of the adhesion coefficient-slip ratio curve in large slip can effectively improve the traction/braking adhesion redundancy and the upper limit of adhesion utilization,thereby ensuring the traction/braking performance and operation safety of the train.Originality/value–Most existing studies focus on the wheel-rail adhesion coefficient values and variation patterns under different medium conditions,without considering whether the rail surface with different medium can provide sufficient traction/braking utilized adhesion coefficient for the train.Therefore,there is a risk of traction overspeeding/braking skidding.This study analyzes whether the rail surface with different medium can provide sufficient traction/braking utilized adhesion coefficient for the train and whether there is redundancy.Based on these findings,relevant measures for the reasonable and optimized utilization of adhesion are derived to further ensure operation safety of the train.

Anisotropic NdFeB/SmCoCuFeZr composite bonded magnet prepared by warm compaction process

Anisotropic NdFeB/SmCoCuFeZr composite bonded magnets were prepared by warm compaction process. The effects of adding SmCoCuFeZr magnetic powder on the properties of anisotropic bonded NdFeB magnet were investigated in this work. The results show that, both magnetic properties and temperature stability of the bonded magnet can be improved by adding fine SmCoCuFeZr magnetic powder. In the present study, the optimal content of SmCoCuFeZr magnetic powder was about 20 wt.%, in this case, the Br, Hcj, and(BH)maxof the NdFeB/SmCoCuFeZr composite magnet achieved 0.943 T, 1250 kA/m, and168 kJ/m^3, respectively.

Rail temperature rise characteristics caused by linear eddy current brake of high-speed train

The rail temperature rises when the linear eddy current brake of high-speed train is working,which may lead to a change of rail physical characteristics or an effect on train operations.Therefore,a study concerning the characteristics of rail temperature rise caused by eddy current has its practical necessity.In the research,the working principle of a linear eddy current brake is introduced and its FEA model is established.According to the generation mechanism of eddy current,the theoretical formula of the internal energy which is produced by the eddy current is deduced and the thermal load on the rail is obtained.ANSYS is used to simulate the rail temperature changes under different conditions of thermal loads.The research result shows the main factors which contribute to the rising of rail temperature are the train speed,brake gap and exciting current.The rail temperature rises non-linearly with the increase of train speed.The rail temperature rise curve is more sensitive to the exciting current than the air gap.Moreover,the difference stimulated by temperature rising between rails of 60 kg/m and 75 kg/m is presented as well.