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C23H14Cl4N6O4, triclinic, P1̄ (no. 2), a = 9.044(2) Å, b = 11.340(2) Å, c = 11.812(3) Å, α = 95.470(17)°, β = 105.46(2)°, γ = 90.084(18)°, V = 1161.8(5) Å3, Z = 2, Rgt(F) = 0.0914, wRref(F2) = 0.2547, T = 296 K.

The microwave radiometer can detect and retrieve temperature and humidity profiles with high spatial and temporal resolution throughout the day. However, microwave radiometers have few detection frequencies in the middle and upper layers, making them easily affected by clouds. After integrating cloud information into brightness temperature data, the improvement in detection accuracy in the middle and upper layers still remains insufficient, failing to meet accuracy standards required for relative humidity. With the construction of a national ground-based remote sensing vertical profile system, the continuous observation of cloud radar and microwave radiometer at the same site has been achieved, enhancing the spatial and temporal resolution. Combined with the relationship between humidity and cloud formation, a comprehensive quality control method is proposed for relative humidity using cloud radar and microwave radiometer. It plays a crucial role in enhancing the accuracy of humidity profile of microwave radiometer under cloudy conditions.By analyzing the characteristic relationship between the cloud radar reflectivity factor and the radiosonde relative humidity, a piecewise correction method for the microwave radiometer relative humidity of the combined cloud radar is proposed. Error correction results are analyzed using the radiosonde and ERA5 data. It shows that there is a positive linear correlation between the relative humidity and the reflectivity factor, the relative humidity in the middle of the cloud region is approximately saturated, and the relative humidity variation trend with the height of the cloud exit region and the cloud entry region is approximately symmetric about a certain height. Under the condition of stratiform clouds, the root mean square error of relative humidity by microwave radiometer decreases by 7.99% and 8.91% when comparing with radiosonde and ERA5, and the absolute value of median deviation decreases by 12.62% and 13.05%, respectively. The absolute median deviation also decreases. Further investigation indicates the method is also effective under the condition of convection cloud, but the relative humidity in the cloud region after correction is larger than that of sounding and ERA5, and the median deviation changes from negative deviation to positive deviation. Therefore, the relative humidity segment correction method of combing cloud radar can realize the continuous real-time correction of the relative humidity profile of microwave radiometer, which partly improves the observation quality of microwave radiometer under cloud conditions.

C48H68Cl4N8O8Ni4, tetragonal, I41/a (no. 88), a = 16.9137(5) Å, c = 19.5028(13) Å, V = 5579.2(5) Å3, Z = 4, Rgt (F) = 0.0391, wRref (F 2) = 0.1221, T = 293 K.

C18H15N7O4Zn, triclinic, P 1‾ $\overline{1}$ (no. 2), a = 9.1100(8) Å, b = 10.6451(7) Å, c = 12.0479(8) Å, α = 95.238(5)∘, β = 112.154(7)∘, γ = 112.971(7)∘, V = 956.56(13) Å3, Z = 2, R gt(F) = 0.0264, wR ref(F 2) = 0.0731, T = 298 K.

Using a high temperature solid state reaction at 1600 ℃ for 6 h, (Nd1－xCax)(Al1－xFex)O3－x/2(x=0, 0.1, 0.2, 0.3) was synthesized by introducing Ca2+ and Fe3+ into NdAlO3, and spark plasma sintering (SPS) ceramic samples were used to investigate the effects of Ca2+ and Fe3+ addition on the phase composition, emissivity and ferroelasticity of NdAlO3. The results show that a solid solution can be successfully fabricated through the high temperature solid state reaction. The doping of Ca2+ and Fe3+ in NdAlO3 increases oxygen vacancies and slight lattice distortion occurs, emissivity of NdAlO3 within the wavelength range of 2.5-10 μm increases the maximum to 0.9. The introduction of impurity ions makes the phase gradually transform from rhombohedral to cubic, leading to the ferroelastic domains vanish. However, the fracture toughness of ceramic samples remains at a high level.

The application of metal additive manufacturing technology and products in the aviation field requires optimized structural design at macroscale and precise manufacture control at microscale. As one of the typical features of additive manufacture, microstructure inevitably affects the material performance. The research has shown that the uniformity, plasticity, and fatigue fracture characteristics of additive manufacturing materials are often inferior to traditional materials, while their strength, hardness, wear resistance, and some microscale properties are often better than traditional materials. The size effect in the micro/nano-scale and the heterogeneous characteristics of materials have a significant impact on metal materials with microstructures. Under different microstructures, materials can achieve a better balance between strength and ductility, which is also applicable to additively manufactured metals. Therefore, the process characteristics of additive manufacturing and the heterogeneities introduced by human design are both expected to significantly improve the comprehensive performance of metals, which have important guiding value for the application of metal additive manufacturing in the aviation field. However, since many of the mechanism of these phenomena are still unclear, the strength-ductility synergistic and antagonistic relationships with other properties of the materials are also worth further research.

Based on the self-made Zr0.5Hf0.5C precursor and commercial liquid polycarbosilane, C/Zr0.5Hf0.5C-SiC composite was successfully prepared by the precursor impregnation and pyrolysis(PIP) process. The influence of the thickness of pyrolytic C coating on the structure and bending properties of composite materials was studied. The results show that the self-made Zr0.5Hf0.5C precursor can be converted into Zr0.5Hf0.5C solid solution at a relatively low temperature of 1400 ℃. Because of its good permeability, the transformed Zr0.5Hf0.5C matrix exists in both the inter-bundle and intra-bundle regions of the C/Zr0.5Hf0.5C-SiC composite, which presents as a layered structure on SiC matrix. The phase composition of C/Zr0.5Hf0.5C-SiC composite mainly includes C, SiC and Zr0.5Hf0.5C. The densities of three groups of composites with different thicknesses of pyrolytic C coating (0.67, 0.84, 1.36 μm) are 2.07, 1.99, 1.98 g/cm3, respectively. SiC content in the composite decreases with the increase of the thickness of pyrolytic C coating. The three groups of composites with different thicknesses show pseudoplastic fracture mode during bending loading tests, bending strength, bending modulus and fracture toughness are above 410 MPa, 60 GPa and 15.6 MPa·m1/2, respectively. Good interface bonding and pre-introduced SiC matrix are the keys to obtaining excellent bending properties of C/Zr0.5Hf0.5C-SiC composites.

Using carbon fiber cloth with different areal densities and tow sizes, two kinds of carbon fiber preforms with same carbon cloth laminated structure were produced through different z-direction stitching methods. Then, C/C-SiC composites were prepared by combining chemical vapor infiltration (CVI) with gas silicon infiltration (GSI). The influence of carbon fiber preform structure on the microstructure and mechanical properties of CVI-GSI C/C-SiC composites was studied. The results show that the density, phase composition, structure, and properties of the two composites prepared from preforms with the same fiber volume fraction and C/C preform density are significantly different. The smaller carbon fiber tow (1K) and carbon cloth surface density (92 g/m2), as well as the larger voids left by lock stitching, provide more sufficient channels for the infiltration of Si vapor in the GSI reaction process. Thus T1 composite finally prepared has low porosity, uniform structure, and higher performance, with bending strength, modulus, and fracture toughness of 300.97 MPa, 51.75 GPa, and 11.32 MPa·m1/2, respectively. The comprehensive control of the initial preform structure and the C/C intermediate structure is the key to the preparation of high performance C/C-SiC composites by the CVI-GSI process.

[Objective] The objective of this study was to scientifically examine the coupling rule, spatial characteristics, and formation mechanism of population and built-up area changes under the differential population flow in county units, and improve the multi-scale and multi-level allocation mechanism for the intensive use of land resources. [Methods] Taking the urban agglomeration of the Beijing-Tianjin-Hebei region as the study area and using GIS spatial analysis and econometric models, this study explored the pattern, coupling relationship, and driving mechanism of population density change in the built-up areas at the county level. [Results] The study found that: (1) From 2009 to 2018, population of 61% of the areas in the Beijing-Tianjin-Hebei region decreased. The population growth was concentrated in peripheral districts of Beijing and Tianjin and municipal districts of Hebei Province. Meanwhile, the corridor between Beijing and Tianjin and the central urban areas of prefecture-level cities in Hebei were the high-growth areas of the built-up areas in the region, and the growth rate of the built-up areas of both Beijing and Tianjin slowed down significantly. (2) Population density in the built-up areas of the Beijing-Tianjin-Hebei region declined by 323 people per square kilometer, and substantial decline areas were concentrated in counties in Hebei Province. The coupling relationship between population and built-up area changes was dominated by the pattern of “shrinkage and extensive” type from 2009 to 2018, which increased pressure on land resource allocation. (3) Population flow and industrial development model significantly influenced population density change in the built-up areas, but the increase of urbanization rate did not exhibit a significant effect on land use efficiency. [Conclusion] The relationship change between the populations and built-up areas of county-level units in the Beijing-Tianjin-Hebei region is significantly different, and the pressure of intensive use of the built-up areas in counties surrounding central cities, especially located in the central and southern plain farming areas of Hebei Province is increasing. Therefore, it’s urgent to innovate the multi-scale coordination mechanism of provinces, prefectural cities and counties, and optimize the multi-level policy system for reusing idle land in urban-rural areas.

Inversion of gravity data is one the important steps in the interpretation of practical data. The detection of sharp boundaries between anomalous bodies and host rocks is an interesting point in the geological frameworks. The gravity inversion with sparsity constraint is a useful method to recover block subsurface density distribution, which is efficiently used for the quantitative interpretation of gravity data. The reweighted regularized method is a useful method to solve the inverse problem. However, in this type, we must face the updating gravity forward matrix and large matrix operation. The application of Lanczos bidiagonalization method can reduce the size of data and matrix in the inversion to resolve the large scale inversion problem. However, a very important problem is not resolved, which is update of reweighted forward matrix and new Lanczos bidiagonalization matrix. Here, an adaptive Lanczos bidiagonalization method is studied to select the Lanczos bidiagonalization factor. And a new projected method with adaptive Lanczos bidiagonalization method is study to avoid the updating sparsity reweighted function. We calculate the reweighted forward matrix and Lanczos bidiagonalization matrix only one time, which can essentially reduce the computational complexity. The inversion results of synthetic data show that the new improved method is faster and better than common reweight regularized Lanczos bidiagonalization method to produce an acceptable solution for focusing inverse problem. The improvement of adaptive Lanczos bidiagonalization in sparsity gravity inversion is also tested on gravity data collected over the Mobrun massive sulfide ore body in Noranda, Quebec, Canada. The inversion results indicate a remarkable correlation with true structure of the ore body that is achieved from drilling data.

Cancer prevention and treatment are currently the focus of most research. Dose verification is an important step for reducing the improper dose deposition during radiotherapy. To mend the traditional gel dosimeters for 3D dose verification, a novel rare-earth nanoparticle-based composite gel was prepared, which has good radioluminescence property and reusability. It is a promising phantom material for the new 3D gel dosimeter. TEM, DLS, FT-IR, TGA, and spectrofluorometer were used to determine the chemical structure, micromorphology, and optical performance. Compared to the traditional gel dosimeters, the composite gel has a good linear relationship between the light intensity excited by X-ray and the tube current. Furthermore, it may measure the dose distribution immediately in situ, which reduces errors and saves time. This work provides a new idea for the research of 3D gel dosimeters and promotes the safe and effective use of radiotherapy.

The ultrafine-grained (UFG) CrCoNi medium entropy alloys (MEAs) with excellent mechanical and tribological performances were fabricated by combining rolling deformation and annealing treatment. The microstructures of CrCoNi MEAs were characterized by electron backscatter diffraction (EBSD) and transmission electron microscope (TEM). The results show that the materials annealed at 650 ℃ for 10 min after cryogenic rolling display a yield strength as high as 1135 MPa and a graceful uniform ductility of 14.1%. Another group of materials rolled at room temperature followed by annealing at 650 ℃ for 20 min exhibit a yield strength of 987 MPa and an improved ductility of 18.6%. In addition, the grains of CrCoNi medium entropy alloys after above treatment are greatly refined to an average grain size of 0.81 μm and 0.92 μm respectively. The ultra-high strength is due to the grain boundary strengthening of high angle boundaries and dislocation strengthening of low angle boundaries. Remarkably, such UFG MEAs exhibit high wear resistance.

Solar insecticidal lamps Internet of Things (SIL-IoTs) is a novel physical agricultural pest control implement, which is an emerging paradigm that extends Internet of Things technology towards Solar Insecticidal Lamp (SIL). SIL-IoTs is composed of SIL nodes with functions of preventing and controlling of agricultural migratory pests with phototaxis feature, which can be deployed over a vast region for the purpose of ensuring pests outbreak area location, reducing pesticide dosage and monitoring agricultural environmental conditions. SIL-IoTs is widely used in agricultural production, and a number of studies have been conducted. However, in most current research projects, fault diagnosis has not been taken into consideration, despite the fact that SIL-IoTs faults have an adverse influence on the development and application of SIL-IoTs. Based on this background, this research aims to analyze the characteristics and challenges of fault diagnosis in SIL-IoTs, which naturally leads to a great number of open research issues outlined afterward. Firstly, an overview and state-of-art of SIL-IoTs were introduced, and the importance of fault diagnosis in SIL-IoTs was analyzed. Secondly, faults of SIL nodes were listed and classified into different types of Wireless Sensor Networks (WSNs) faults. Furthermore, WSNs faults were classified into behavior-based, time-based, component-based, and area affected-based faults. Different types of fault diagnosis algorithms (i.e., statistic method, probability method, hierarchical routing method, machine learning method, topology control method, and mobile sink method) in WSNs were discussed and summarized. Moreover, WSNs fault diagnosis strategies were classified into behavior-based strategies (i.e., active type and positive type), monitoring-based strategies (i.e., continuous type, periodic type, direct type, and indirect type) and facility-based strategies (i.e., centralized type, distributed type and hybrid type). Based on above algorithms and strategies, four kinds of fault phenomena: 1) abnormal background data, 2) abnormal communication of some nodes, 3) abnormal communication of the whole SIL-IoTs, and 4) normal performance with abnormal behavior actually were introduced, and fault diagnosis tools (i.e., Sympathy, Clairvoyant, SNIF and Dustminer) which were adapted to the mentioned fault phenomena were analyzed. Finally, four challenges of fault diagnosis in SIL-IoTs were highlighted, i.e., 1) the complex deployment environment of SIL nodes, leading to the fault diagnosis challenges of heterogeneous WSNs under the condition of unequal energy harvesting, 2) SIL nodes task conflict, resulting from the interference of high voltage discharge, 3) signal loss of continuous area nodes, resulting in the regional link fault, and 4) multiple failure situations of fault diagnosis. To sum up, fault diagnosis plays a vital role in ensuring the reliability, real-time data transmission, and insecticidal efficiency of SIL-IoTs. This work can also be extended for various types of smart agriculture applications and provide fault diagnosis references.

La2Zr2O7 powders were synthesized by solid-state reaction method. After spray granulation, the La2Zr2O7 coatings were fabricated by air plasma spray technique. The effect of heat treatment time on the properties of La2Zr2O7 coatings was investigated, focusing on phase composition, microstructure evolution and thermal conductivity. The results show that a single pyrochlore phase of La2Zr2O7 coating has been successfully fabricated. And the average porosity is 11.3%. The phase composition and porosity do not change with the prolongation of heat treatment time. The thermal conductivity of the as-sprayed coating can be as low as 0.392 W?m–1?K–1. A number of amorphous structures exist in the as-sprayed coating, which can effectively block the transmission of phonons. With an increase of thermal exposure time at 1300 ℃ in air, the amorphous structure is gradually transformed into crystalline structure, and the phonon transfer efficiency is obviously improved, resulting in a significant increase in the thermal conductivity of the coating. Interestingly, after heat treatment, the rebound effect of thermal conductivity at high temperature didn’t appear in this research.

Range Cell Migration Correction (RCMC) represents an important advance in moving target imaging in the airborne single antenna high-resolution SAR system. In this paper, we propose a new four-step RCMC approach combined with parameter estimation that overcomes the drawbacks of high computation and low accuracy in high-resolution. First, we use the Hough transform and the energy balancing method to estimate the range velocity and correct the range walk. Next, we perform a range curvature correction in the range-Doppler domain by using the initial Doppler rate. Thirdly, we accurately estimate the Doppler rate using Mapdrift technology. Finally, we correct the residual range curvature by the accurate Doppler rate. Compared with traditional algorithms, the proposed method requires less computation and is robust in the high-resolution SAR system. In this paper, we present a mathematical model and validate its effectiveness using both simulation and real data.

This paper presents a radar working mode based on multi-pulse combination and coding, and the basic concept and theoretical model of pulse-coded radar are established. Using multi-pulse combination and the modulation of the time, frequency, and phase parameters, the pulse signal is coded in time domain, frequency domain, or time-frequency domain. Based on multi-pulse combination and coding, a new working method and theoretical basis are provided to solve the problem of coupling constraints among parameters of traditional pulse and continuous wave radars, which limits the performance of the radar system. Based on the fabricated Synthetic Aperture Radar (SAR) and its tests, the pulse coding, target signal recovery method, and pulse coding performance were studied. The study and test results show that the sampling rate of radar signals could be reduced to break through the limitation of Nyquist sampling theorem and simplify the difficulty of system implementation using frequency division pulse coding method. A 5 GHz bandwidth signal was sampled with 4.8 GHz and was recovered without distortion in the radar system, and an SAR imaging resolution of 0.03×0.03 m was realized. By using the time domain pulse coding method with an increase of duty cycle, the signal-to-noise ratio was improved by over 20 dB. By using the two-dimensional pulse coding method, the SAR signal ambiguity was removed, and the imaging swath of over 90 km was realized. The theoretical and test results verify the significant advantages of the pulse coding method in improving radar performance, by which a new technical approach for the realization of high performance radar system is provided.

Cyclo crosslinked polyphosphazenes (PPNs) were prepared by Hexachlorocyclotriphosphazene (HCCP) with unique P = n structure and active p-cl group and green compound phloretin. The synthesis pro cess of polyphosphazene nanospheres with Hexachlorocyclotriphosphazene as the main body and phloretin was discussed. The effects of pH value and solid-liquid ratio of solution on the adsorption of uranium by pol yphosphazene nanospheres were studied. The results show that polyphosphazene nanospheres are off white powder in appearance and spherical in microstructure. When the pH value of the solution is 4 and the solid-l iquid ratio is 0.5g ·L-1, the maximum adsorption rate of uranium is obtained.

Poly (cyclotriphosphazene-co-4,4 '- diaminodiphenylsulfone) (PZD) microspheres were synthesi zed by precipitation polymerization of Hexachlorocyclotriphosphazene (HCCP) and polyfunctional organic monomers. The products were characterized by FTIR, SEM-EDS, XPS and bet. The adsorption behavior of PZD microspheres for uranium (VI) in aqueous solution and the influence of adsorption behavior were disc ussed. The results show that the PZD microspheres have a certain adsorption capacity for uranium (VI) in a queous solution. When pH = 3.5, adsorption time is 6h, solid-liquid ratio is 2.0g • L-1 and initial concentration of uranium (VI) is 30mg • L-1, the adsorption rate of uranium reaches the maximum.

This paper provides a brief review of the development in Unmanned Aerial Vehicle (UAV) borne SAR technology, and gives a summary on the important areas of UAV SAR, including the operation mode, key facilitating technology, performance and specifications, typical systems and applications. According to the characteristics and attributes of UAV platform, the paper focuses on the current development of high resolution, motion compensation and innovative operation mode of the UAV SAR payload. On the demonstration of high resolution, full polarization and interferometric UAV SAR systems, the technologies of top level design on modular reconfiguration, real-time image formation and multi-dimentional motion compensation involved are introduced in detail. Also, the future development trends of UAV SAR technology is discussed as well.

New ferritic P92 steel is widely used in modern power plants due to its good combination of mechanical and physical properties. However, cracks are often formed in the welded sections during the fabrication or service. In order to ensure the structure integrity, the effects of residual stresses need to be considered. The objective of this paper is to investigate the influence of arc travelling speed and welding sequences on the residual stresses distribution in the welded sections of P92 pipes by finite element method (FEM). Results show that arc travelling speed and welding sequences have great effects on residual stresses distribution. With the arc travelling speed increasing, the residual stresses increase. Meanwhile, welding sequences of case B present smaller residual stresses and more symmetrical distribution of residual stresses at the weld centre line. Therefore, using slower arc travelling speed and case B welding sequences can be useful to decrease the residual stresses, which provides a reference for optimizing the welding technology and improving the fabrication process of new ferritic P92 welded pipes with small diameter and thick wall.

In this research, the effects of three different pretreatment methods, physical pulverizing, steam blasting and hydrogen peroxide oxidizing, on ethanol preparation from corn straw were compared. The results showed that the content of reducing sugar in corn straw briquette with grinding and steam blasting pretreatment were 2 and 1.5 times higher than that without pretreatment. In the final product, the concentration of ethanol and rate of alcohol increased about 3.8 and 2 times, respectively. Besides, the reducing sugar content, ethanol content and alcohol yield in corn stalks soaked in hydrogen peroxide were 7 times higher than the untreated. The cellulose can be effectively isolated after being soaked in hydrogen peroxide with a concentration of 2.5% for 72 hours, as well as better degradation of lignin and hemicellulose. The amount of ethanol and the yield of alcohol were 1.9 and 3.3 times higher than physical pulverization and steam blasting. In brief, it is declared that hydrogen peroxide pretreatment can easily destroy the lignocellulosic cellulose of maize straw and improve the conversion rate of cellulose, which might be beneficial for the production of fuel ethanol.

In this paper, a novel K-means clustering algorithm is proposed. Before running the traditional Kmeans, the cluster centers should be randomly selected, which would influence the time cost and accuracy. To solve this problem, we utilize density distribution analysis in the traditional K-means. For a reasonable cluster, it should have a dense inside structure which means the points in the same cluster should tightly surround the center, while separated away from other cluster canters. Based on this assumption, two quantities are firstly introduced: the local density of cluster center ρi and its desperation degree δi, then some reasonable cluster centers candidates are selected from the original data. We performed our algorithm on three synthetic data and a real bank business data to evaluate its accuracy and efficiency. Comparing with Traditional K-means and K-means++, the results demonstrated that the improved method performs better.