Multiferroic magnetoelectric composite systems such as ferromagnetic-ferroelectric heterostructures have recently attracted an ever-increasing interest and provoked a great number of research activities, driven by profound physics from coupling between ferroelectric and magnetic orders, as well as potential applications in novel multifunctional devices, such as sensors, transducers, memories, and spintronics. In this Review, we try to summarize what remarkable progress in multiferroic magnetoelectric composite systems has been achieved in most recent few years, with emphasis on thin films; and to describe unsolved issues and new device applications which can be controlled both electrically and magnetically.

R esearch on the magnetoelectric (ME) eff ect, discovered more than a century ago [1], progressed through pioneering work in the 1950s and 1960s, and has now seen a resurgence driven by long-term technological aspirations. With the trends toward device miniaturization, there is ever-increasing interest in combining electronic and magnetic properties into multifunctional materials to produce a single device component that can perform more than one task. Multiferroic ME materials are particularly appealing not only because they have the properties of their parent compounds, but also because interactions between the magnetic and electric orders lead to additional functionalities.From the viewpoint of material constituents, multiferroic ME materials can essentially be divided into two types: single-phase [2,3] and composite [4,5]. According to the original defi nition, a singlephase multiferroic material is one that possesses at least two of the 'ferroic' properties, such as ferroelectricity, ferromagnetism or ferroelasticity. While ME composites are multiphase materials composed of diff erent phases, neither phase supports the ME eff ect.Magnetoelectric coupling describes the infl uence of a magnetic (electric) fi eld on the polarization (magnetization) of a material. It may arise directly between the two order parameters as in single-phase multiferroics, or indirectly via strain/stress as in ME composites. Several recent articles have summarized and reviewed research progress in single-phase multiferroic ME materials [2,3], and accordingly, this review will instead focus on composite multiferroic materials.Th e ME eff ect in composite materials is known as a product tensor property, fi rst proposed by van Suchtelen in 1972 [5], that results from the cross interaction between the two phases in the composite. As illustrated schematically in Figure 1, the composite ME eff ect is a result of the product of the magnetostrictive eff ect (magnetic/mechanical eff ect) in the magnetic phase and the piezoelectric eff ect (mechanical/ electrical eff ect) in the piezoelectric phase. Multiferroic magnetoelectric composite nanostructuresYao Wang, Jiamian Hu, Yuanhua Lin and Ce-Wen Nan * Tsinghua University, ChinaMultiferroics are attracting increasing interest and provoking much research activity driven by the profound physics of these materials, the coexistence and coupling of ferroelectric and magnetic orders, and the potential applications in novel multifunctional devices such as sensors, transducers, memories and spintronics. Multiferroic magnetoelectric (ME) composite systems, such as ferromagnetic-ferroelectric heterostructures, which off er a novel route for integrating ferroelectric and ferromagnetism, have been widely studied in recent years. In these ME composite systems, ME coupling is strain-mediated, that is, the strain induced in one component, either by magnetostriction in the ferromagnetic or by the piezoelectric eff ect in the ferroelectric, is transferred to the other component, altering the polarization or ma...

Cycle slip detection and repair is a prerequisite for high-precision global navigation satellite system (GNSS)-based positioning. With the modernization and development of GNSS systems, more satellites are available to transmit triple-frequency signals, which allows the introduction of additional linear combinations and provides new opportunities for cycle slip detection and repair. In this paper, we present a new real-time cycle slip detection and repair method under high ionospheric activity for undifferenced Global Positioning System (GPS)/BeiDou Navigation Satellite System (BDS) triple-frequency observations collected with a single receiver. First, three optimal linearly independent geometry-free pseudorange minus phase combinations are selected to correctly and uniquely determine the cycle slips on the original triple-frequency carrier phase observations. Then, a second-order time-difference algorithm is employed for the pseudorange minus phase combinations to mitigate the impact of between-epoch ionospheric residuals on cycle slip detection, which is especially beneficial under high ionospheric activity. The performance of the approach is verified with static GPS/BDS triple-frequency observations that are collected with a 30 s sampling interval under active ionospheric conditions, and observations are manually inserted with simulated cycle slips. The results show that the method can correctly detect and repair cycle slips at a resolution as small as 1 cycle. Moreover, kinematic data collected from car-driven and airborne experiments are also processed to verify the performance of the method. The experimental results also demonstrate that the method is effective in processing kinematic data.

The effects of land cover on urban-rural and intra-urban temperature differences have been extensively documented. However, few studies have quantitatively related air temperature to land cover composition at a local scale which may be useful to guide landscape planning and design. In this study, the quantitative relationships between air temperature and land cover composition at a neighborhood scale in Beijing were investigated through a field measurement campaign and statistical analysis. The results showed that the air temperature had a significant positive correlation with the coverage of man-made surfaces, but the degree of correlation varied among different times and seasons. The different land cover types had different effects on air temperature, and also had very different spatial extent dependence: with increasing buffer zone size (from 20 to 300 m in radius), the correlation coefficient of different land cover types varied differently, and their relative impacts also varied among different times and seasons. At noon in summer, ∼37% of the variations in temperature were explained by the percentage tree cover, while ∼87% of the variations in temperature were explained by the percentage of building area and the percentage tree cover on summer night. The results emphasize the key role of tree cover in attenuating urban air temperature during daytime and nighttime in summer, further highlighting that increasing vegetation cover could be one effective way to ameliorate the urban thermal environment.