Search

Abstract Background There is an increasing need to account for genotype-by-environment (G × E) interactions in livestock breeding programs to improve productivity and animal welfare across environmental and management conditions. This is even more relevant for pigs because selection occurs in high-health nucleus farms, while commercial pigs are raised in more challenging environments. In this study, we used single-step homoscedastic and heteroscedastic genomic reaction norm models (RNM) to evaluate G × E interactions in Large White pigs, including 8686 genotyped animals, for reproduction (total number of piglets born, TNB; total number of piglets born alive, NBA; total number of piglets weaned, NW), growth (weaning weight, WW; off-test weight, OW), and body composition (ultrasound muscle depth, MD; ultrasound backfat thickness, BF) traits. Genetic parameter estimation and single-step genome-wide association studies (ssGWAS) were performed for each trait. Results The average performance of contemporary groups (CG) was estimated and used as environmental gradient in the reaction norm analyses. We found that the need to consider heterogeneous residual variance in RNM models was trait dependent. Based on estimates of variance components of the RNM slope and of genetic correlations across environmental gradients, G × E interactions clearly existed for TNB and NBA, existed for WW but were of smaller magnitude, and were not detected for NW, OW, MD, and BF. Based on estimates of the genetic variance explained by the markers in sliding genomic windows in ssGWAS, several genomic regions were associated with the RNM slope for TNB, NBA, and WW, indicating specific biological mechanisms underlying environmental sensitivity, and dozens of novel candidate genes were identified. Our results also provided strong evidence that the X chromosome contributed to the intercept and slope of RNM for litter size traits in pigs. Conclusions We provide a comprehensive description of G × E interactions in Large White pigs for economically-relevant traits and identified important genomic regions and candidate genes associated with GxE interactions on several autosomes and the X chromosome. Implementation of these findings will contribute to more accurate genomic estimates of breeding values by considering G × E interactions, in order to genetically improve the environmental robustness of maternal-line pigs.

Thermal stability is an important indicator to measure the reliability of aerospace equipment, and the space thermal environment is complex, and the commonly used thermal analysis software for ground equipment can no longer meet the needs. For this reason, based on the thermal design analysis software SINDA/FLUINT, taking a spacecraft as the research object, the thermal balance equation is first established. Then, use the thermal desktop software to establish a numerical model, and use the SINDA/FLUINT software to solve the heat transfer process. Finally, the thermal desktop is used to post-process the calculation results and analyse the thermal radiation of the spacecraft.

The progress of the Belt and Road Initiative (BRI) has not only created an unprecedented opportunity for the export of China’s agricultural products but also resulted in the opportunity to promote the Global Good Agricultural Practices (GlobalGAP) in China’s agricultural production. In this paper, the SWOT method was adopted to analyze the strengths, weaknesses, opportunities, and threats of promoting GlobalGAP in China’s agricultural production in the context of the BRI.

FGH96 is a Chinese made powder metallurgy nickel based superalloy. This reserach aims to investigate the effect of stress on the microstructure of the worst fatigue life at 600°C. The specimens were first polished by abrasive paper and then electropolished to elimate the effect of surface residual stress. The fatigue tests were conducted at 600°C, and the loading ratio was 0.05 at the frequency of 5Hz. Tests were conducted at 900, 1000, 1100, 1200MPa respectively. The fatigue life under the same condition were compared and the fractography of specimens were examined under SEM to further identify the life-limiting factors of the material. The initiation mode transferred from facet initiated to inclusion initiated from lower stress level to higher stress level. Meanwhile, the initiation position transferred from internal to surface with the increase of stress level. This means at higher stress level, fatigue life is mainly limited by inclusion at surface while at lower stress level the limit is controlled by internal facet.

The influence of orientation and temperature on the fatigue crack growth of a directionally solidification superalloys named DZ125 were investigated in this study. The specimens were designed based on ASTM E647 standard and the compliance method was employed to monitor the crack growth. Tests were conducted at room temperature, 760°C and 850°C respectively. The longitudinal and transverse orientation were both studied in this tests. Results show that the orientation dependence is weak at elevated temperature compared with that at room temperature. However, the temperature influences the fatigue crack growth rate significantly and the largest difference can be an order of magnitude on the da/dN-ΔK graph. But the reduction in higher ΔK area of elevated temperature can still be observed. Potential reasons and hypothesis were explained in this paper. In addition, the crack growth mode appears to transfer from type I with the increase of temperature which also reflects the influence of temperature.

This essays aims at introducing the setup for the multi-scale in-situ test system which is applied for the fatigue crack initiation test. The setup of the experiment system is first introduced, including the image capturing system, optical path system, image acquisition and storage system and the three-axis mobile platform. Then the preparation of micro speckle and the corresponding technique for spatial adjustment are improved to realize the DIC measurement in micro scale. Finally three experiments from macro-meso scale to macro scale: fatigue initiation test, the observation of micro crack and the fatigue crack growth rate in macro scale were conducted to verify the application of the system. The test result can indicate the location of crack initiation, the crack growth rate and the evolution of displacement/strain field, etc.

The effects of operational conditions on the resistance moment of a rotary energy recovery device have been systematically investigated through the computational fluid dynamics in this paper. Based on the structural characteristics of the rotary energy recovery device, the hydro-static bearing was established on both sides of the rotor. Simulation results indicate that for the rotation resistance moment generated by the rotor internal flow path, the rotation speed is linearly positive with the rotational resistance moment. For the rotation resistance moment generated by the clearance flow, the rotation speed is also positively correlated with the rotational resistance moment. The circular clearance size is negatively correlated with the rotation resistance moment, and the endcover fluid film size is negatively correlated with the rotation resistance moment. The boundary speed between laminar flow and turbulent flow was found by comparing the changing trend of rotational resistance moment. The obtained relation between clearance, the speed of the rotor and resistance moment provides a simple way to predict the resistance moment of the device, which will be beneficial to design the energy-efficient rotary energy recovery device

This paper proposes the development of an Agent framework for tourism recommender system. The recommender system can be featured as an online web application which is capable of generating a personalized list of preference attractions for tourists. Traditional technologies of classical recommender system application domains, such as collaborative filtering, content-based filtering and content-based filtering are effectively adopted in the framework. In the framework they are constructed as Agents that can generate recommendations respectively. Recommender Agent can generate recommender information by integrating the recommendations of Content-based Agent, collaborative filtering-based Agent and constraint-based Agent. In order to make the performance more effective, linear combination method of data fusion is applied. User interface is provided by the tourist Agent in form of webpages and mobile app.

Along with the rapid development of mobile games and the popularity of Google Android operating system, the Android mobile game designed for recreation, exercise thinking will become mainstream. This paper mainly introduces the development process of mobile game and analyzes the key technologies in combination with development of tank war game based on Android system.