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A magnetic-field sensor with self-reference characteristic based on metal–dielectric–metal (MDM) plasmonic waveguides and a magnetic fluid (MF) is proposed and theoretically investigated. Independent dual resonances are supported by the coupled resonator–waveguide system. The physical mechanisms of dual resonances are analyzed by the temporal coupled-mode theory. The transmission response to an external magnetic field is explored by using the remarkable tunability of the refractive index of the MF. Based on the different dependence of two resonances on the external field, a magnetic-field sensor with self-reference characteristic is achieved. The magnetic-field nanosensor shows an excellent performance with a high sensitivity of 27 pm/Oe, i.e., 270 pm/mT. The proposed sensor takes advantage of the refractive-index tunability of the MF and the compactness of the MDM waveguide structure. This research may open new opportunities to design nanoscale magnetic sensors with good performance.

We prepared a series of Li2O-CaO-Al2O3-SiO2/P2O5 glass ceramics doped with Mn2+ and Mn2+/Tm3+ ions by traditional high-temperature melting method and thermal annealing technology. The XRD pattern, TEM image, excitation and emission spectra of the samples were studied. The luminescent characteristics of the samples had been discussed in detail. The luminescent color of Mn2+-doped samples can vary from green to red by adjusting the ratio of SiO2 to P2O5. Under 360 nm excitation, the Mn2+/Tm3+-codoped sample can generate white light, whose CIE coordinate is (X = 0.328, Y = 0.314). The value is very close to the standard equal energy white-light illumination (X = 0.333, Y = 0.333). This study is helpful for exploring novel luminescent materials for white light-emitting diodes.

We prepared Nd3+/Pr3+/Yb3+ tri-doped phosphate glass by high-temperature melting method. The glass can efficiently transfer the sunlight into the near-infrared luminescence (∼1000 nm). Which can be applied to the spectrum converter of the solar battery of crystalline silicon. It is hopeful for improving the efficiency of solar battery.

With the development of magnetic refrigerant technology, magnetic substances with a large magnetocaloric effect (MCE) and nearly zero thermal hysteresis are desired. Although Ni-Mn based Heusler alloys have been found to produce large MCEs and have attracted increasing attention recently, the occurrence of thermal hysteresis accompanying MCE due to the nature of first-order phase transition limits its applications with magnetic refrigeration. Up to now, an effective theory or method to eliminate this thermal hysteresis is still lacking. Here, we propose to utilize the feature of magnetic transition at the morphotropic phase boundary (MPB) to eliminate thermal hysteresis and thus design a MPB-involved phase diagram in Heusler alloys of Ni50Mn36Sb14-xInx (x = 0-14). As theoretically expected, the magnetic transition at MPB really yields a MCE with a negligible thermal hysteresis (∼0 K) and the refrigerant capacity arrives at a maximum value of 108.2 J kg-1 at the composition of x = 9. Our findings provide an effective way to design large MCE materials with zero thermal hysteresis.

Fluorosilicate glass was prepared by high-temperature melting method to explore highly efficient luminescence materials for amorphous silicon solar cells. Absorption, excitation and emission spectra of the glass were measured. The optical characters of the glass were discussed in details. The glass can efficiently convert sunlight into red light. Our glass can be applied to amorphous silicon solar cells as a converter of solar spectrum.

Thulium, terbium, and manganese tridoped phosphate glass ceramic was prepared by high-temperature melting method and heat annealing technology. The sample can emit strong white light under 355 nm excitation. The luminescence intensities and peak positions keep unchanged in the temperature range of 25-300°C. The phosphate glass ceramic material shows good property of thermal stability, which can be exploited for the phosphor of white-light-emitting diode.

The emergence of climate change (CC) is affecting and changing the development of the natural environment, biological species, and human society. In order to better understand the influence of climate change and provide convincing evidence, the need to quantify the impact of climate change is urgent. In this paper, a climate change model is constructed by using a radial basis function (RBF) neural network. To verify the relevance between climate change and extreme weather (EW), the EW model was built using a support vector machine. In the case study of Canada, its level of climate change was calculated as being 0.2241 (&ldquo, normal&rdquo, ), and it was found that the factors of CO2 emission, average temperature, and sea surface temperature are significant to Canada&rsquo, s climate change. In 2025, the climate level of Canada will become &ldquo, a little bad&rdquo, based on the prediction results. Then, the Pearson correlation value is calculated as being 0.571, which confirmed the moderate positive correlation between climate change and extreme weather. This paper provides a strong reference for comprehensively understanding the influences brought about by climate change.

Studying the spatial distribution of real estate price can not only help consumers to choose the suitable real estate, but also help urban planners to make better decisions. Under the background big data, a new perspective of research on urban real estate prices is produced. Based on the real estate parameters of ordinary residential buildings in Xining city, ArcGIS software is used to conduct the nearest neighbor distance analysis, and it is found that the residential buildings in the area presented significant agglomeration. Then, Moran’s I index is selected for spatial autocorrelation analysis, which proves the positive spatial correlation of real estate prices in Xining city. Finally, the spatial distribution map of real estate prices is obtained by fitting the real estate prices in the research area with the statistical analysis of land, which finds the area of Chengxi is the center of local housing price, and the price is decreasing gradually around other areas. In addition, the main factors affecting housing prices in four areas can be obtained by analyzing the distribution figure, which gives a significant reference for residents and policy planners.

To explore white-light-emitting materials, a series of Dy3+-doped polymethyl methacrylate (PMMA) samples are prepared by polymerization method. Excitation spectra and emission spectra are experimentally investigated. It is found that the luminous color of the PMMA sample doped with 0.1 mol% Dy3+ ion is white to the naked eye under 326 nm excitation. The CIE chromaticity coordinates (X = 0.321, Y = 0.336) of the emission are close to the standard white-light illumination (0.333, 0.333). The results are helpful in developing luminescent materials aimed for white light-emitting diodes. Keywords: Luminescence, Optical materials and properties, Rare-earth ions

We prepared the Y2O3 nanocrystals doped with Tm3+ and Ce3+ ions by the sol-gel method. The luminescence lifetimes, excitation and emission spectra have been studied in detail. The Tm3+/Ce3+ doped Y2O3 nanocrystals can emit strong 813 nm infrared with the excitation of 698 nm red light. The excitation wavelength at 698 nm and emission wavelength at 813 nm are located in the weak absorption area of biological tissues, which can enhance the quality of optical imaging.

Electromagnetically induced transparency (EIT) phenomenon is observed in simple metamaterial which consists of concentric double U-shaped resonators (USRs). The numerical and theoretical analysis reveals that EIT arises from the bright-bright mode coupling. The transmission spectra at different polarization angle of incident light shows that EIT transparency window is polarization sensitive. More interestingly, Fano resonance appears in the transmission spectrum at certain polarization angles. The sharp and asymmetric Fano lineshape is high valuable for sensing. The performance of sensor is investigated and the sensitivity is high up to 327 GHz/RIU. Furthermore, active control of EIT window is realized by incorporating photosensitive silicon. The proposed USR structure is simple and compact, which may find significant applications in tunable integrated devices such as biosensor, filters, and THz modulators.

There is always a need to extract more accurate regional common mode component (CMC) series from coordinate time series of Global Positioning System (GPS) stations, which would be of great benefit to describe the deformation features of the Earth&rsquo, s surface with more reliability. For this purpose, this paper combines all 11 International Global Navigation Satellite System (GNSS) Service (IGS) stations in China with over 70 stations selected from the Crustal Movement Observation Network of China (CMONOC) to compute CMC series of IGS stations by using a principal component analysis (PCA) method under cases of one whole region and eight sub-regions. The comparison results show that the percentage of first-order principal component (PC1) in North, East and Up components increase by 10.8%, 16.1% and 25.1%, respectively, after dividing the whole China region into eight sub-regions. Meanwhile, Root Mean Square (RMS) reduction rates of residual series that have removed CMC also improve obviously after partitioning. In addition, we compute displacements of these IGS stations caused by environmental loadings (including atmospheric pressure loading, non-tidal oceanic loading and hydrological loading) to analyze their contributions to the non-linear variation in GPS coordinate time series. The comparison result shows that the method we raise, PCA filtering in sub-regions, performs better than the environmental loading corrections (ELCs) in improving the signal-to-noise ratio (SNR) of GPS coordinate time series. This paper raises new criteria for selecting appropriate CMONOC stations around IGS stations when computing sub-regional CMC, involving three criteria of interstation distance, geology and self-condition of stations themselves. According to experiments, these criteria are implemental and effective in selecting suitable stations, by which to extract sub-regional CMC with higher accuracy.

A strategy is demonstrated for enhanced upconversion luminescence and significantly realized tunable fluorescence lifetime of NaLuF4 by simply doping KF. The upconversion luminescence intensities of the green and red are remarkably enhanced for molar ratio KF/Ln(Lu/Yb/Er) 80% doped NaLuF4 microcrystals compared to that without KF. Moreover, the fluorescence lifetime of NaLuF4 is tunable in a wide range depending on the doping molar ratio of KF. In a single 541 nm emission channel, 7 different fluorescence lifetimes ranging from 87.44μs to 285.47μs can be obtained. These superior performances are attributed to the tailored local environment. In addition, we use three of the materials to demonstrate multiplexing. Under 980 nm excitation, it displays the fake information “8”. However, scanning the security pattern in the time domain shows the real messages “1” and “9”.

In this paper, we study broadband second harmonic generation (SHG) in an imperfect nonlinear photonic crystal in which defects are introduced with random lengths. We show that the efficient SHG output is obtained when the length of each defect varies near certain specialized values. The bandwidth of the SHG output broadens with the increasing randomness of defect length. Moreover, the SHG bandwidth is nearly unaffected only when the total length of the whole structure is long enough. The disordered structure also exhibits good tolerance to the fabrication error, which provides a way to control SHG intensity and bandwidth separately.

When multi-UAVs work together to perform tasks, the invulnerability of UAV formation is very important. In this paper, we present a strategy to improve the invulnerability of UAV formation by adding super wires. Firstly, the invulnerability of randomly generated UAV formation is studied, and it is shown that the invulnerability of UAV formation is the worst under dynamic betweenness centrality attack. Secondly, we present an optimized Louvain algorithm to explore the community structure in UAV formation. Finally, according to the intermediate centrality and community structure of UAV formation, we added super wires between specific nodes in the UAV community and the UAV base station. Our experimental simulation shows that the proposed algorithm can effectively reduce the average betweenness centrality of UAV formation, and improve the network efficiency and invulnerability of UAV formation.

Recently, X-ray pulsar-based navigation (XPNAV) as a significant navigation method has been widely used in deep space exploration. However, the accuracy of XPNAV is limited to the existence of the pulsar direction error. To improve the performance of XPNAV, we have proposed a novel algorithm named &ldquo, the modified augmented state extended Kalman filter&rdquo, (MASEKF). The algorithm considers the high-order terms of direction error and then adds a more precise direction error into state equation and measurement equation. In the simulation, by comparing the performance of MASEKF, EKF, and ASEKF at the same time, it is found that MASEKF has better performance in the accuracy and stability, and the results also demonstrate that MASEKF algorithm has faster convergence speed. This paper provides a strong reference for other improvements of algorithms towards direction error. The purpose of this study is to establish MASEKF and add the direction error into the measurement equation and the state equation, so as to realize the coordination and symmetry of the algorithm.

Heterogeneity which widely exists in human society and the biological world, has been proved to be one of the cases that can promote the level of cooperation. For example, the level of cooperation in a heterogeneous network is relatively high when compared with that in a homogeneous network. Recent research has revealed that the effect of heterogeneity in evolutionary game theory depends on the specific definition of heterogeneity and updating rule. In this paper we explore how heterogeneity reproductive ability affects the evolution of cooperation. In this paper we associate reproductive ability with the payoff. A player with a higher payoff and a better environment is more reproductive, which is a common phenomenon existing from human society to bacterial systems. Excitingly, we find that our new constructed rule can dramatically promote cooperation in evolutionary prisoner's dilemma game. From our numerical result, we also find that moderate heterogeneity can better promote the level of cooperation. Several figures are drawn to explain why heterogeneity reproductive ability can promotes the level of cooperation. Our work finds a new mechanism to promote cooperation in spatial prisoner's dilemma game and reveals why cooperation mushrooms with heterogeneity reproductive ability.

A plasmonic, refractive, index nanosensor is investigated theoretically and numerically in two U-shaped cavities side-coupled to a metal–dielectric–metal (MDM) waveguide. A transparency window between two transmission dips is observed. The physical origin of the transmission phenomenon is revealed by mapping the magnetic field distribution. Independent double resonances are realized through the proposed design. Double resonances showed diverse responses to the variations of the structural dimensions. In particular, they presented different dependences on a refraction index of the medium in an individual resonator. One resonance exhibited a remarkable shift with the increase of the refraction index; however, the other resonance remained unchanged. On the basis of this unique characteristic of differing sensitivities, self-reference sensing is discussed. The nanosensor yielded a high sensitivity of 917 nm/RIU and a figure of merit of 180 RIU−1. This work is helpful in terms of the design of on-chip optical sensors with high sensitivity and improved detection accuracy in complicated environments.

Smart growth is widely adopted by urban planners as an innovative approach, which can guide a city to develop into an environmentally friendly modern city. Therefore, determining the degree of smart growth is quite significant. In this paper, sustainable degree (SD) is proposed to evaluate the level of urban smart growth, which is established by principal component regression (PCR) and the radial basis function (RBF) neural network. In the case study of Yumen and Otago, the SD values of Yumen and Otago are 0.04482 and 0.04591, respectively, and both plans are moderately successful. Yumen should give more attention to environmental development while Otago should concentrate on economic development. In order to make a reliable future plan, a self-organizing map (SOM) is conducted to classify all indicators and the RBF neural network-trained indicators are separate under different classifications to output new plans. Finally, the reliability of the plan is confirmed by cellular automata (CA). Through simulation of the trend of urban development, it is found that the development speed of Yumen and Otago would increase slowly in the long term. This paper provides a powerful reference for cities pursuing smart growth.

To explore fluorescence temperature sensor, Yb3+/Er3+ co-doped phosphate glass ceramic was prepared by high-temperature melting method and thermal annealing technology. The luminescent spectra of the sample were measured under 975 nm excitation at the temperature ranges of 25–300 °C. The strong green up-conversion emissions, coming from the transitions of Er3+ ion: 2H11/2-4I15/2 and 4S3/2-4I15/2, were observed. The fluorescence intensity ratio of the two green up-conversion emissions can change with the increasing of temperature. The sensitivity of Er3+/Yb3+ co-doped phosphate glass ceramic reached the maximal value of ∼0.0077 K−1. The sensitivity is relatively flat at the high temperature region. Our research is valuable to developing fluorescence temperature sensor. Keywords: Luminescence, Optical materials and properties, Sensor

We experimentally demonstrate that the spectral resolution of Fourier transform interferometer could be greatly enhanced by using the dispersive property of semiconductor GaAs in the near infrared region and obtain the frequency distribution of the input light from interference pattern by defining a new frequency transform factor. The results show the effectiveness of this method in the slow light interference system.

An ultracompact plasmonic refractive index sensor based on Fano resonance is proposed. The sensor comprises a metal–insulator–metal waveguide with a stub and a side-coupled split-ring resonator. The effect of structural parameters on Fano resonance and the refractive index sensitivity of the system are analyzed in detail by investigating the transmission spectrum. Simulation results show that Fano resonance has different dependences on the parameters of the sensor structure. The reason is further discussed based on the field pattern. The peak wavelength and lineshape can be easily tuned by changing the key parameters. Furthermore, dual Fano resonance effects with different frequency intervals are obtained, which are mainly induced by the symmetry breaking of the structure. The proposed sensor yields sensitivity higher than 1.4×103 nm/RIU and a figure of merit of 1.2×105. The sensitivity and figure of merit can be further improved by optimizing the geometry parameters.

In this paper, we demonstrate that the topological polaritonic states of a two-dimensional coupled matter–light system can be optically controlled. By introducing a squeezed light field, we generalized the model of topological polaritons, where the matter–light coupling constant winds in momentum space, leading to the nontrivial topology. The bulk excitation spectrum, polariton wave function, topological invariant, and edge mode spectrum are calculated. It is found that mixing the excitons with nonsqueezing photons will result in a time-reversal-symmetry-breaking quantum-spin-Hall-like polaritonic state. However, the quantum-Hall-like state arises when the photonic part of the polaritons is squeezed. Driven by the varying degree of squeezing, there is a topological phase transition with the closing of the bulk excitation gap. Across the phase transition, the direction of edge mode propagation is reversed, which is demonstrated by an edge mode simulation. Such a feature may provide an opportunity for realizing one-way edge channels with adjustable directionality.