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To analysis the electromagnetic interference effect of airport enclosure security system on VOR, this paper studies the airport enclosure security system in the millimeter wave radar electromagnetic radiation of special, according to the airport enclosure security system in the electromagnetic radiation of millimeter wave radar test data, in combination with the practical installation position of millimeter wave radar, calculation of millimeter wave radar electromagnetic radiation of VOR signal interference at the airport. The results show that the millimeter wave radar of airport enclosure security system will not interfere with the VOR signal of the airport in actual operation.

The navigation performance of Global Navigation Satellite System was affected by distortional space signal. Therefore, the threat model for analog distortional signal of BDS is researched and analyzed. Firstly, the mathematical model for ranging code distortion of BDS is established and analyzed in theoretically. Then, the correlation function and power spectrum density function were deduced. Finally, in accordance with S-curve locking point bias of ranging code distortion, the impact on measurement performance was deeply analyzed. The simulation results demonstrate that the correlation peak and power spectrum were deformation, therefore pseudo range measurement error was generated, the accuracies of BDS including ranging accuracy and positioning accuracy were reduced, and the integrity for augmentation system was also reduced.

According to the definition of signal in space (SIS) user range error (URE) and the Root Mean Square URE(rms URE) calculation method given in the Global Positioning System Standard Positioning Service Performance Standard (GPS-SPS-PS), the Beidou Navigation Satellite System (BDS) Instantaneous URE (IURE) and rms URE formulas are deduced in detail considering the elevation constrains. On the one hand, BDS URE is calculated by the orbital error and clock error calculated from the ephemeris data, and BDS URE is calculated by the measured receiver data on the other hand. The correctness of the formula is verified by comparing the results of the two methods.

Knowledge of cooperative breeding in birds from longitudinal studies is available only for a small proportion of species. This paper reports data from a 12-year study on the Tibetan Ground Tit Pseudopodoces humilis. On average, 27.2% (range: 13.0–36.1%) of monogamous pairs in each year contained one (85.4%) or more (14.6%) male helpers, 83.7% of which were yearlings staying on natal territories. Most helpers (89.6%) helped once and then bred independently. Adults had male-biased sex ratios, low annual survival rates (averaging 0.50) and shorter longevities (averaging 1.8 years) compared with low-altitude avian cooperative breeders, suggesting that mate shortage promotes helping behaviour in this species. Incest occurred rarely (2.1% of pairs), probably because kin recognition occurs through year-around living in family groups. There was a low level (3.1% of broods) of extra-pair parentage, which could facilitate the maintenance of cooperative breeding.

The operational status of the instrument landing system directly affects aircraft landing and airport operational standards. Whose changeable status cannot be determined during the flight inspection period of the ILS. Proposes an innovative manner by analyze the QAR data from the routine flights of domestic airports. In order to improve the accuracy of recorded QAR data, this paper used the integrated track latitude and longitude correction model and the integral sliding track model. The signal in space change trend of the airport instrument landing system was also analyzed, to monitor hen the quality and operation status of the instrument landing system signal.

Life-history theory predicts a trade-off between current and future reproduction to maximize lifetime fitness. In cooperatively breeding species, where offspring care is shared between breeders and helpers, helper presence may influence the female breeders' egg investment, and consequently, survival and future reproductive success. For example, female breeders may reduce egg investment in response to helper presence if this reduction is compensated by helpers during provisioning. Alternatively, female breeders may increase egg investment in response to helper presence if helpers allow the breeders to raise more or higher quality offspring successfully. In the facultatively cooperative-breeding Tibetan ground tit Pseudopodoces humilis, previous studies found that helpers improve total nestling provisioning rates and fledgling recruitment, but have no apparent effects on the number and body mass of fledglings produced, while breeders with helpers show reduced provisioning rates and higher survival. Here, we investigated whether some of these effects may be explained by female breeders reducing their investment in eggs in response to helper presence. In addition, we investigated whether egg investment is associated with the female breeder's future fitness. Our results showed that helper presence had no effect on the female breeders' egg investment, and that egg investment was not associated with breeder survival and reproductive success. Our findings suggest that the responses of breeders to helping should be investigated throughout the breeding cycle, because the conclusions regarding the breeders' adjustment of reproductive investment in response to being helped may depend on which stage of the breeding cycle is considered.

A summary of Bayesian phylogenetic mixed models showing the significant predictors of sex bias in helping (male-only or both-sex) across 88 cooperatively breeding bird species. Predictor variables were selected following a stepwise forward regression method.

Among avian cooperative breeders, help in raising offspring is usually provided by males or by both sexes. Sex bias in helping should evolve in response to sex-specific ecological constraints on independent reproduction, with mate shortage for males and breeding vacancy shortage for each sex. Given that male-biased adult sex ratios are prevalent among birds, we predict that male-only helping mainly occurs in temperate species where fast population turnovers deriving from low adult annual survival allow all adult females to hold breeding vacancies, whereas some males overflow as helpers, and both-sex helping in tropical species where saturated habitats prevent not only males, but also females from breeding themselves. As expected, we found that across species, adult survival increased towards tropical zones and warmer climates, and higher adult survival tended to be associated with both-sex helping. Furthermore, sex bias in helping was predicted by latitude and ambient temperature. Our findings of demographic response of species to climate as a potential determinant of bias in helper sex uncover how ecological constraints operate to limit independent reproduction in sex-specific ways.

Among avian cooperative breeders, help in raising offspring is usually provided by males or by both sexes. Sex bias in helping should evolve in response to sex-specific ecological constraints on independent reproduction, with mate shortage for males and breeding vacancy shortage for each sex. Given that male-biased adult sex ratios are prevalent among birds, we predict that male-only helping mainly occurs in temperate species where fast population turnovers deriving from low adult annual survival allow all adult females to hold breeding vacancies, whereas some males overflow as helpers, and both-sex helping in tropical species where saturated habitats prevent not only males, but also females from breeding themselves. As expected, we found that across species, adult survival increased towards tropical zones and warmer climates, and higher adult survival tended to be associated with both-sex helping. Furthermore, sex bias in helping was predicted by latitude and ambient temperature. Our findings of demographic response of species to climate as a potential determinant of bias in helper sex uncover how ecological constraints operate to limit independent reproduction in sex-specific ways.