Comprehensive Overview of Populus simonii Research in the Recent Years

As an important ecological tree species in northern China, Populus simonii plays a crucial role in maintaining ecological balance and promoting environmental sustainability. The academic community has conducted a series of in-depth studies on this species, covering key areas such as genomics, survival mechanisms, and genetic breeding. Through the analysis of the genomic structure and function of P. simonii, we have not only revealed the molecular basis for its adaptation to harsh environments but also identified key genes that promote its growth and resistance to pests and diseases. Furthermore, exploring the survival mechanisms of P. simonii has deepened our understanding of its stress resistance traits, including how it effectively copes with abiotic stresses such as drought, salinization, and heavy metal pollution. In genetic breeding, significant progress has been made through the application of modern biotechnology, improving the growth rate and wood quality of P. simonii and enhancing its environmental adaptability and disease resistance. These research findings have not only enriched our knowledge of the biological characteristics of P. simonii but also provided a solid scientific foundation for its application in ecological restoration, forestry production, and environmental management.

Cramer-Rao bound and signal-to-noise ratio gain in distributed coherent aperture radar

This paper studies the estimation performance of the coherent processing parameter （CPP）, including time delay differences and phase synchronization errors among different apertures of the distributed coherent aperture radar （DCAR）. Firstly, three architectures of signal processing in the DCAR are introduced. Secondly, the closed-form Cramer-Rao bound （CRB） of the CPP estimation is derived and compared. Then, the closed-form CRB is verified by numerical simulations. Finally, when the next generation radar works in a fully coherent mode, the closed-form signal-to-noise ratio （SNR） gain of the three architectures is presented.

Cramer-Rao bound of joint estimation of target location and velocity for coherent MIMO radar

The optimal estimation performance of target parameters is studied. First, the general form of Cramer-Rao bound （CRB） for joint estimation of target location and velocity is derived for coherent multiple input multiple output （MIMO） radars. To gain some insight into the behavior of the CRB, the CRB with a set of given orthogonal waveforms is studied as a specific case. Second, a maximum likelihood （ML） estimation algorithm is proposed. The mean square error （MSE） of the ML estimation of target location and velocity is obtained by Monte Carlo simulation and it approaches CRB in the high signal-to-noise ratio （SNR） region.

The gross α and β radioactivity levels of drinking water source in one oil industrial city in northeast China

Objective:To investigate the grossαandβradioactivity levels of drinking water source in the city,the largest oil field production base in northeast China,in order to ensure the safety of drinking water and public health.Methods:The water samples from three drinking water sources were collected and tested in the dry and wet season,respectively.The grossαradioactivity was measured by standard curve method,grossβwas measured by thin sample method.Results:Totally 184 samples were collected from the three sampling areas in dry and wet season respectively.The average values of grossαandβradioactivity levels in the drinking water source area were(0.24±0.09)and(0.30±0.17)Bq/L respectively.The average activity concentration of grossαand grossβin the dry season was(0.23±0.09)and(0.29±0.18)Bq/L,respectively.The grossαandβradioactivity levels gradually decreased from the intake to the end of the reservoir of drinking water source areas.Conclusions:The grossαandβradioactivity levels and distribution of drinking water source areas in this city were all lower than the drinking water limit issued by China and the reference level recommended by the World Health Organization.The radioactivity of water body of the drinking water source was within the normal background level.