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Although the maximum carboxylation rate (Vcmax) is an important parameter to calculate the photosynthesis rate for the terrestrial biosphere models (TBMs), current models could not satisfactorily estimate the Vcmax of a crop because the Vcmax is always changing during crop growth period. In this study, the Breathing Earth System Simulator (BESS) and light response curve (LRC) were combined to invert the time-continuous Vm25 (Vcmax normalized to 25 °C) using eddy covariance measurements and remote sensing data in five maize sites. Based on the inversion results, we propose a Two-stage linear model using leaf age to estimate crop Vm25. The leaf age can be readily calculated from the date of emergence, which is usually recorded or can be readily calculated from the leaf area index (LAI), which can be readily obtained from high spatiotemporal resolution remote sensing images. The Vm25 used to calibrate and validate our model was inversely solved by combining the BESS and LRC and using eddy covariance measurements and remote sensing data in five maize sites. Our Two-stage linear model (R2 = 0.71–0.88, RMSE = 5.40–7.54 μmol m−2 s−1) performed better than the original BESS (R2 = 0.01–0.67, RMSE = 13.25–18.93 μmol m−2 s−1) at capturing the seasonal variation in the Vm25 of all of the five maize sites. Our Two-stage linear model can also significantly improve the accuracy of maize gross primary productivity (GPP) at all of the five sites. The GPP estimated using our Two-stage linear model (underestimated by 0.85% on average) is significantly better than that estimated by the original BESS model (underestimated by 12.60% on average). Overall, our main contributions are as follows: (1) by using the BESS model instead of the BEPS model coupled with the LRC, the inversion of Vm25 took into account the photosynthesis process of C4 plants; (2) the maximum value of Vm25 (i.e., PeakVm25) during the growth and development of maize was calibrated; and (3) by using leaf age as a predictor of Vm25, we proposed a Two-stage linear model to calculate Vm25, which improved the estimation accuracy of GPP. [ABSTRACT FROM AUTHOR]

Maize, the most important cereal crop worldwide, is moderately sensitive to salt stress. Given the challenges of soil salinization, developing methods to screen and cultivate salt-tolerant maize varieties is vital for enhancing food security. Among the options, process model-based assisted screening is an effective method for faster and more thorough screening of salt-tolerant varieties. In this study, a method for quickly screening salt-tolerant and high-yielding crop varieties is proposed by combining a coupled model of crop growth and water–salt response with fitness function. Then, this method was applied to the saline areas of the Hetao Plain in China to demonstrate its applicability. This study includes three parts. Firstly, field trial data from 10 commonly grown maize varieties in Hetao Plain (i.e., Xianyu 335, Yinyu 238, Jindan 73, Deke 622, DK-815, Heyu 157, Xianyu 1321, Jinrun 919, Tianci 19, and Xianyu 1225) were used to calibrate the model for different maize varieties. Moreover, model accuracy was evaluated using four indexes including the regression coefficient (b), coefficient of determination (R²), root mean square error (RMSE), and Nash–Sutcliffe efficiency coefficient (NSE). Secondly, scenario simulations were conducted using the calibrated model by setting nine initial salinity scenarios to simulate daily dynamic crop growth and soil water–salt changes for the 10 maize varieties. Finally, salt-tolerant and high-yielding maize varieties were screened based on the fitness function method during crop growth periods. The results showed that the simulation model was applicable and functioned effectively for all 10 maize varieties in the region, with the determination coefficient (R2) and Nash–Sutcliffe efficiency coefficient (NSE) of simulated plant height and leaf area index being above 0.90. Furthermore, the R2 of soil water content, soil electrical conductivity, and groundwater depth are 0.51, 0.52, and 0.60, respectively. Afterward, the fitness function values were calculated to bridge the linkage between simulated indicators and scenarios to screen varieties step by step according to the predetermined percentage of screening. Jindan 73, Xianyu 1225, and DK-815 were eventually determined as the most suitable salt-tolerant and high-yielding maize varieties. Therefore, the above results show that the proposed method is suitable for saline crop variety screening with flexibility and applicability. [ABSTRACT FROM AUTHOR]

The current challenges facing large-diameter timber forests include low yield and low eco-economic benefit. As a result, the development of large-diameter timber forests has become one of the most important strategies for the development of forestry in China. The present study employed bibliometric analysis and Citespace software v.6.1.R3 to examine the literature from CNKI and WOS databases spanning 2002–2021. This analysis aimed to identify the research hotspots and trends in large-diameter timber trees while providing theoretical support and guidance for developing large-diameter timber forests. The research results showed the following data. (1) The number of articles published increased year by year, approximately 4.8 times in 20 years. (2) The journal "Forest Ecology and Management", where the number of papers is up to 53, has a significant impact on the field of large-diameter timber research. The Tropical Forestry Experimental Center of the Chinese Academy of Forestry and the Wageningen University and Research in the Netherlands possess strong research capabilities, with average citation frequencies of the articles of 26.8 and 51.5, respectively. (3) Research on large-diameter trees focuses on "large-diameter timber cultivation technology and cultivation measures", "forest conservation management", "large-diameter timber stand structure", and "dynamic monitoring of large-diameter timber growth". "Selection of suitable seed sources", "Innovation of large-diameter timber cultivation technology", and "improvement of large-diameter timber forest management mode" are the future research trends of large-diameter trees. In the future, it will be a challenge to realize the sustainable development of large-diameter timber resources. Concurrently, long-term monitoring and scientific management of large-diameter timber forests will be a key issue in promoting the development of large-diameter timber forests. [ABSTRACT FROM AUTHOR]

CO2 geological storage combined with deep saline water recovery technology (CO2-EWR) is one of the most effective ways to reduce carbon emissions. Due to the complex structural features, it is difficult to use CO2-EWR technology in Huaiyin Sag, Subei basin, East China. In this study, the multi-source information superposition evaluation technology of GIS was utilized for the selection of CO2 storage sites and water displacement potential target areas in this area, which mainly focused on the sandstone reservoirs of Cretaceous Pukou Formation. Based on the results, a three-dimensional injection–extraction model was established. Various scenarios with different production/injection well ratios (PIR) were simulated. Research has shown that the suitability of the surrounding site of Huaiyin Power Plant can be divided into two levels: relatively suitable and generally suitable; the area in the generally suitable level accounts for more than 80%. At a PIR of 1, CO2 is distributed asymmetrically, whereas at PIRs of 2 or 4, CO2 is distributed symmetrically. When the number of production wells is constant, a higher injection rate results in a faster expansion rate of the CO2 plume. This means that the time taken for the CO2 plume to reach the production wells is shorter. Reservoir pressure increases rapidly after more than 60 years of CO2 injection at lower PIR values, while at higher PIRs, reservoir pressure eventually stabilizes. Higher PIR values correspond to higher gas saturation, indicating a greater capacity for CO2 sequestration with more producing wells. When PIR = 4, the total CO2 injection increased by 55.73% compared to PIR = 1. However, the extraction of saline decreases with an increase in the number of producing wells, resulting in a decrease in replacement efficiency. This study provides a theoretical basis and technical support for the implementation of large-scale CO2-EWR engineering and technology demonstration in this region. [ABSTRACT FROM AUTHOR]

The soil freezing characteristic curve (SFCC) describes the relationship between the freezing point and unfrozen water content, which are two critical parameters in depicting the heat, solute, and water transport in frozen soil. In this paper, we propose a novel Generalized Clapeyron Equation (GCE)-based model, the GCE-Salt Model, to better capture the SFCC in frozen soil in the presence of solute. It keeps the matric potential Ψf in the GCE as its original meaning and incorporates the effect of solute potential in the equilibrium freezing temperature. The performance of our GCE-Salt Model was validated by both lab and field experimental data and compared with related models (Combined Model and GCE-Tan Model). The GCE-Salt Model performed exceptionally well in extremely saline soil and it performed well in both non-saline and saline soil. (1) Our GCE-Salt Model could capture the SFCC of non-saline soil equally as well as the Combined Model (NSE = 0.866); (2) our GCE-Salt Model performed similarly well as the Combined Model and a little better than the GCE-Tan Model for the slightly to highly saline soil (NSE ≥ 0.80 for three models); and (3) our GCE-Salt Model (NSE = 0.919) beat the Combined Model (NSE = 0.863) and the GCE-Tan Model (NSE = 0.62) in capturing the SFCC of extremely saline soil, mainly because the inherent expression of our GCE-Salt Model can more accurately capture the freezing point. Our findings highlight the effect of solute potential on the ice–water change and could improve the understanding of the effect of freezing and thawing on the thermal–hydrological processes, structure of saline soil, and landscape evolution in cold regions. [ABSTRACT FROM AUTHOR]

This study focused on predicting at-risk groups of students at the Open University (OU), a UK university that offers distance-learning courses and adult education. The research was conducted by drawing on publicly available data provided by the Open University for the year 2013–2014. The semester's time series was considered, and data from previous semesters were used to predict the current semester's results. Each course was predicted separately so that the research reflected reality as closely as possible. Three different methods for selecting training data were listed. Since the at-risk prediction results needed to be provided to the instructor every week, four representative time points during the semester were chosen to assess the predictions. Furthermore, we used eight single and three integrated machine-learning algorithms to compare the prediction results. The results show that using the same semester code course data for training saved prediction calculation time and improved the prediction accuracy at all time points. In week 16, predictions using the algorithms with the voting classifier method showed higher prediction accuracy and were more stable than predictions using a single algorithm. The prediction accuracy of this model reached 81.2% for the midterm predictions and 84% for the end-of-semester predictions. Finally, the study used the Shapley additive explanation values to explore the main predictor variables of the prediction model. [ABSTRACT FROM AUTHOR]

Dismantling the waste printed circuit boards (WPCBs) of obsolete mobile phones is essential for resource recycling and environmental protection. An automated WPCB disassembly equipment based on the hot-vibration process was designed and applied, with optimized process conditions of a heating temperature of 250 °C and an equipment amplitude of >3.66 mm. The dismantling rate for electronic components and metal shields was 98%, but disassembly of components with underfill was less effective. Both simulation and actual measurement results of the equipment's thermal field showed that the temperature inside the disassembly bin was uniform, with a maximum temperature difference of 6–8 °C. The area of the low-temperature region accounted for approximately 5% of the total area. The acceleration ranged from 2.11 to 8.28 g when using the disassembly force model. This equipment and process can be applied to disassemble large quantities of WPCBs. [ABSTRACT FROM AUTHOR]

This study compares the accuracy and effectiveness of our novel 3D-printed titanium cutting guides with intraoperative surgical navigation for performing intraoral condylectomy in patients with mandibular condylar osteochondroma (OC). A total of 21 patients with mandibular condylar OC underwent intraoral condylectomy with either 3D-printed cutting guides (cutting guide group) or with surgical navigation (navigation group). The condylectomy accuracy in the cutting guide group and navigation group was determined by analyzing the three-dimensional (3D) discrepancies between the postoperative computed tomography (CT) images and the preoperative virtual surgical plan (VSP). Moreover, the improvement of the mandibular symmetry in both groups was determined by evaluating the chin deviation, chin rotation and mandibular asymmetry index (AI). The superimposition of the condylar osteotomy area showed that the postoperative results were very close to the VSP in both groups. The mean 3D deviation and maximum 3D deviation between the planned condylectomy and the actual result were 1.20 ± 0.60 mm and 2.36 ± 0.51 mm in the cutting guide group, and 1.33 ± 0.76 mm and 4.27 ± 1.99 mm in the navigation group. Moreover, the facial symmetry was greatly improved in both groups, indicated by significantly decreased chin deviation, chin rotation and AI. In conclusion, our results show that both 3D-printed cutting-guide-assisted and surgical-navigation-assisted methods of intraoral condylectomy have high accuracy and efficiency, while using a cutting guide can generate a relatively higher surgical accuracy. Moreover, our cutting guides exhibit user-friendly features and simplicity, which represents a promising prospect in everyday clinical practice. [ABSTRACT FROM AUTHOR]

We systematically studied several of the most traditional hollow-core anti-resonant fiber (HC-ARF) structures, with the aim of achieving low confinement loss, single-mode performance, and high insensitivity to bending in the 2 µm band. Moreover, the propagation loss of fundamental mode (FM), higher-order mode (HOMs), and the higher-order mode extinction ratio (HOMER) under different geometric parameters were studied. Analysis showed that the confinement loss of the six-tube nodeless hollow-core anti-resonant fiber at 2 µm was 0.042 dB/km, and its higher-order mode extinction ratio was higher than 9000. At the same time, a confinement loss of 0.040 dB/km at 2 µm was achieved in the five-tube nodeless hollow-core anti-resonant fiber, and its higher-order mode extinction ratio was higher than 2700. [ABSTRACT FROM AUTHOR]

The radiometric calibration network (RadCalNet) comprises four pseudo-invariant calibration sites (PICS): Gobabeb, Baotou, Railroad Valley Playa, and La Crau. Due to its site stability characteristics, it is widely used for sensor performance monitoring and radiometric calibration, which require high spatiotemporal stability. However, some studies have found that PICS are not invariable. Previous studies used top-of-atmosphere (TOA) data without verifying site data, which could affect the accuracy of their results. In this study, we analyzed the short- and long-term radiometric trends of RadCalNet sites using bottom-of-atmosphere (BOA) data, and verified the trends revealed by the TOA data from Landsat 7, 8, and Sentinel-2. Besides the commonly used methods (e.g., nonparametric Mann–Kendall and sequential Mann–Kendall tests), a more robust Sen's slope method was used to estimate the magnitude of the change. We found that (1) the trends based on TOA reflectance contrasted with those based on BOA reflectance in certain cases, e.g., the reflectance trends in the red band of BOA data for La Crau in summer and autumn and Baotou were not significant, while the TOA data showed a significant downward trend; (2) the temporal trends showed statistically significant and abrupt changes in all PICS, e.g., the SWIR2 band of La Crau in winter and spring changed by 1.803% per year, and the SWIR1 band of Railroad Valley Playa changed by >0.282% per year, indicating that the real changes in sensor performance are hard to detect using these sites; (3) spatial homogeneity was verified using the coefficient of variation (CV) and Getis statistic (Gi*) for each PICS (CV < 3% and Gi* > 0). Overall, the RadCalNet remains a highly reliable tool for vicarious calibration; however, the temporal stability should be noted for radiometric performance monitoring of sensors. [ABSTRACT FROM AUTHOR]

Landslides pose a greater potential risk to the Sichuan-Tibet Transportation Project, and extensive landslide inventory and mapping are essential to prevent and control geological hazards along the Sichuan-Tibet Transportation Corridor (STTC). Recently proposed landslide detection methods mainly focused on new landslides with high vegetation. In addition, there are still challenges in automatic detection of old landslides using optical images. In this paper, two methods, namely mask region-based convolutional neural networks (Mask R-CNN) and transfer learning Mask R-CNN (TL-Mask R-CNN), are presented for detecting and segmenting new and old landslides, respectively. An optical remote sensing dataset for landslide recognition along the Sichuan-Tibet Transportation Corridor (LRSTTC) is constructed as an evaluation benchmark. Our experimental results show that the recall rate and F1-score of the proposed method for new landslide detection can reach 78.47% and 79.80%, respectively. Transfer learning is adopted to detect old landslides, and our experimental results show that evaluation indices can be further improved by about 10%. Furthermore, TL-Mask R-CNN has been applied to identify ice avalanches based on the characteristics of landslides. It appears that our proposed methods can detect and segment landslides effectively along the STTC with the constructed LRSTTC dataset, which is essential for studying and preventing landslide hazards in mountainous areas. [ABSTRACT FROM AUTHOR]

Featured Application: This work can be applied to the monitoring of mountain fire, ice, lightning strikes, and galloping along the optical fiber composite overhead power transmission lines with ultra-long distances and large measurement ranges. The coherent optical time domain reflectometer (COTDR) is a very important instrument for distributed temperature/strain measurement along the sensing fiber with a large dynamic range and high accuracy. The length of the sensing fiber and the temperature/strain measurement range limit the system performance, especially the measurement efficiency. So, a COTDR system is constructed, and the characteristics of the obtained coherent Rayleigh noise (CRN) are analyzed. Then, in consideration of the temperature/strain measurement range, accuracy, and time efficiency, the temperature/strain demodulation algorithm in noise conditions is studied. With different noise coefficients, the array length with 11, 21, 31, 51, and 101 independent frequency sweeping points are adopted to calculate the cross-correlation coefficients along a standard reference array with 301 independent frequency sweeping points. The results demonstrate that the array length has little influence on the signal processing time, but it can decide the measurement accuracy. To balance the system measurement efficiency and accuracy, it is inferred that, for a sensing fiber with a length of 100 km or more, the optimal independent frequency sweeping points are 101 and the trace average number is 1000. [ABSTRACT FROM AUTHOR]

Multi-mode fiber (MMF) is used in a polarization-sensitive optical time domain reflectometer (OTDR) for vibration event location and spectrum analysis. The vibration events acting on MMF are considered to be the optical polarization state and phase diversifying process for fading noise reduction. In addition, data averaging with continuous positions and the fast Fourier transform (FFT) method is proposed to extract the spectrum of the vibration events. In the experiment, the vibration events are loaded at the positions of 5.167 and 10.145 km, respectively, along MMF. The experimental results demonstrate that the vibration event can effectively diversify the optical polarization state and phase of the Rayleigh scattering light to make the averaged OTDR trace behind the vibration position converge rapidly, which helps to locate corresponding vibration events and extract the vibration spectrum. It is inferred that the new distributed vibration sensor shall have a lower false alarm rate, as it can greatly reduce the errors caused by randomness of the sensing light signals. Additionally, it also saves time in comparison with the method that analyzes the vibration spectra for all the positions along the fiber under test. [ABSTRACT FROM AUTHOR]

This bedside-to-bench study aimed to systematically investigate the value of applying BMP2-loaded calcium phosphate cement (BMP2-CPC) in the restoration of large-scale alveolar bone defects. Compared to deproteinized bovine bone (DBB), BMP2-CPC was shown to be capable of inducing a favorable pattern of bone regeneration and bone remodeling accompanied by active osteoclastogenesis and optimized biomaterial resorption when applied in reconstructive periodontally accelerated osteogenic orthodontics (PAOO) surgery. To verify the regulatory role of osteoclasts in the BMP2-CPC-induced pattern of bone regeneration, in vitro and in vivo studies were designed to elucidate the underlying mechanism. Our results revealed that osteoclasts played a multifaceted role (facilitating osteogenesis, bone remodeling and biomaterial resorption) in the BMP2-CPC-induced bone regeneration. Osteoclasts contributed to the osteogenic differentiation of mesenchymal stem cells (MSCs) by secreting calcium ions, CTHRC1 and PDGF-B. Moreover, the increased osteoclasts promoted the remodeling of new bone and BMP2-CPC resorption, leading to a harmonized replacement of biomaterials with mature bone. In conclusion, the in vitro and in vivo experimental results corresponded with the clinical results and showed the optimized properties of BMP2-CPC in activating osteoclast-driven bone regeneration and remodeling, thus indicating the highly promising prospects of BMP2-CPC as an ideal therapeutic for alveolar bone defects. [ABSTRACT FROM AUTHOR]

This study implemented a stable Regional Reference Frame in Shanghai, East China (called SHRRF), using seven years of continuous GNSS observations from the Shanghai Continuously Operating Reference System stations (SHCORS) to examine reclaimed coast–land subsidence. A well−distributed core station network suitable for regional applications was derived. The instantaneous station coordinates and seven frame parameters (translations, rotations, and scale) were estimated at each epoch through minimum constraint during the process of aligning SHRRF to the International Terrestrial Reference Frame (ITRF14). The average root mean square error (RMSE) of all stations under SHRRF was within 1.5 mm horizontally and 5 mm vertically for most epochs. Simultaneously, compared with the ITRF14 solutions, the average RMSE for each site at all epochs was reduced by ~30% horizontally and ~10% vertically. A temporal consolidation settlement model of the reclaimed soil under self−weight was established by combining a geotechnical−derived model with high precision permanent GNSS vertical solutions under SHRRF. The model indicates that ~50% of settlements occurred within 3.6 years, with the whole subsidence time being 46 years. SHRRF provides a precise regional reference frame for use in many East China geophysical applications besides reclaimed coast–land settlement including hydrologic loading, microplate motions, and critical structure deformation monitoring. [ABSTRACT FROM AUTHOR]

Wide area landslide detection is a major international research hotspot in the field of geological hazards, and the integration of multi-temporal optical satellite images and spaceborne interferometric synthetic aperture radar (InSAR) appears to be an effective way to realize this. In this paper, a technical framework is presented for wide area landslide detection: (i) multi-temporal satellite optical images are used to detect landslides with distinguishable geomorphological features; (ii) Generic Atmospheric Correction Online Service (GACOS) assisted InSAR stacking is employed to generate annual surface displacement rate maps in radar line of sight using satellite SAR images from both ascending and descending tracks, which are in turn utilized to automatically detect active landslides from ground motion using hotspot analysis, and (iii) the distribution characteristics of the detected landslides are investigated by examining their relationships with topographic and hydrological factors. Three expressways in Sichuan Province, China—namely the Yakang (Ya'an-Kangding), Yaxi (Ya'an-Xichang), and Lushi (Luding-Shimian) expressways—and their surrounding regions (a total area of approximately 20,000 square kilometers) were chosen as the study area. A total of 413 landslides were detected, among which 320 were detected using multi-temporal satellite optical images, and 109 were detected using GACOS-assisted InSAR stacking. It should be noted that only 16 landslides were detected by both approaches; these landslides all exhibited not only obvious geomorphological features but also ground motion. A statistical analysis of the topographic and hydrological factors shows that of the detected landslides: 81% are distributed at elevations of 1000–2500 m, over 60% lie within the elevation range of 100~400 m, and 90% present with medium and steep slopes (20°~45°), and 80% are located within areas seeing an annual rainfall of 950~1050 mm. Nine landslides were found to pose potential safety hazards to the expressways. The research findings in this paper have directly benefitted the Sichuan expressways; equally important, it is believed that the technical framework presented in this paper will provide guidance for hazard mitigation and the prevention of transportation hazards in the future. [ABSTRACT FROM AUTHOR]

Object detection is one of the most important and challenging branches of computer vision. It has been widely used in people's lives, such as for surveillance security and autonomous driving. We propose a novel dual-path multi-scale object detection paradigm in order to extract more abundant feature information for the object detection task and optimize the multi-scale object detection problem, and based on this, we design a single-stage general object detection algorithm called Dual-Path Single-Shot Detector (DPSSD). The dual path ensures that shallow features, i.e., residual path and concatenation path, can be more easily utilized to improve detection accuracy. Our improved dual-path network is more adaptable to multi-scale object detection tasks, and we combine it with the feature fusion module to generate a multi-scale feature learning paradigm called the "Dual-Path Feature Pyramid". We trained the models on PASCAL VOC datasets and COCO datasets with 320 pixels and 512 pixels input, respectively, and performed inference experiments to validate the structures in the neural network. The experimental results show that our algorithm has an advantage over anchor-based single-stage object detection algorithms and achieves an advanced level in average accuracy. Researchers can replicate the reported results of this paper. [ABSTRACT FROM AUTHOR]

Light pens for 3D vision coordinate measurement systems are increasingly widely used due to their advantages, such as their small size, convenience of being carried, and widespread applicability. The posture of the light pen is an important factor that affects accuracy. The pose domain of the pen needs to be given so that the measurement system has a suitable measurement range to obtain more qualified parameters. The advantage of the self-calibration method is that the entire self-calibration process can be completed at the measurement site with no auxiliary equipment. After the system camera calibration was completed, we took several pictures of the same measurement point with different poses to obtain the conversion matrix of the picture and subsequently used spherical fitting, the generalized inverse method of least squares, and the principle of position invariance in the pose domain range. The combined stylus tip center self-calibration method calculates the actual position of the light pen probe. The experimental results verify the effectiveness of the method; the measurement accuracy of the system can satisfy basic industrial measurement requirements. [ABSTRACT FROM AUTHOR]

Aberration-corrected scanning transmission electron microscopy (AC-STEM) has evolved into the most powerful characterization and manufacturing platform for all materials, especially functional materials with complex structural characteristics that respond dynamically to external fields. It has become possible to directly observe and tune all kinds of defects, including those at the crucial atomic scale. In-depth understanding and technically tailoring structural defects will be of great significance for revealing the structure-performance relation of existing high-property materials, as well as for foreseeing paths to the design of high-performance materials. Insights would be gained from piezoelectrics and thermoelectrics, two representative functional materials. A general strategy is highlighted for optimizing these functional materials' properties, namely defect engineering at the atomic scale. [ABSTRACT FROM AUTHOR]

The paper describes one promising method and approach for the recycling, reuse, and co-resource treatment of waste photovoltaic silicon and lithium battery anode graphite. Specifically, this work considers the preparation of nano/micron silicon carbide (SiC) from waste resources. Using activated carbon as a microwave susceptor over a very short timeframe, this research paper shows that nano/micron β-SiC can be successfully synthesized using microwave sintering technology. The used sintering temperature is significantly faster and more energy-efficient than traditional processes. The research results show that the β-SiC particle growth morphology greatly affected by the microwave sintering time. In a short microwave sintering time, the morphology of the β-SiC product is in the form of nano/micron clusters. The clusters tended to be regenerated into β-SiC nanorods after appropriately extending the microwave sintering time. In the context of heat conversion and resource saving, the comprehensive CO2 emission reduction is significantly higher than that of the traditional SiC production method. [ABSTRACT FROM AUTHOR]

A global navigation satellite system (GNSS) receiver with multi-antenna using clock synchronization technology is a powerful piece of equipment for precise attitude determination and reducing costs. The single-difference (SD) can eliminate both the satellites and receiver clock errors with the common clock between antennas, which benefits the GNSS short-baseline attitude determination due to its lower noise, higher redundancy and stronger function model strength. However, the existence of uncalibrated phase delay (UPD) makes it difficult to obtain fixed SD attitude solutions. Therefore, the key problem for the fixed SD attitude solutions is to separate the SD UPD and fix the SD ambiguities into integers between antennas. This article introduces the one-step ambiguity substitution approach to separate the SD UPD, through which we merge the SD UPD parameter with the SD ambiguity of the reference satellite ambiguity as the new SD UPD parameter. Reconstructing the other SD ambiguities, the rank deficiency can be remedied by nature, and the new SD ambiguities can have a natural integer feature. Finally, the fixed SD baseline and attitude solutions are obtained by combining the ambiguity substitution approach with integer ambiguity resolution (IAR). To verify the effect of the ambiguity substitution approach and the advantages of the SD observables with a common clock in practical applications, we conducted static, kinematic, and vehicle experiments. In static experiments, the root mean squared errors (RMSEs) of the yaw and pitch angles obtained by the SD observables with a common clock were improved by approximately 80% and 93%, respectively, compared to double-difference (DD) observables with a common clock in multi-day attitude solutions. The kinematic results show that the dispersion of the SD-Fix in the pitch angle is two times less that of the DD-Fix, and the standard deviations (STDs) of the pitch angle for SD-Fix can reach 0.02°. Based on the feasibility, five bridges with low pitch angles in the vehicle experiment environment, which the DD observables cannot detect, were detected by the SD observables with a common clock. The attitude angles obtained by the SD observables were also consistent with the fiber optic gyroscope (FOG) inertial navigation system (INS). This research on the SD observables with a common clock provides higher accuracy. [ABSTRACT FROM AUTHOR]

Among various ways to eliminate the multipath effect in high-precision global navigation satellite system positioning, the multipath hemispherical map (MHM) is a typical multipath correction method based on spatial domain repeatability, which is suitable for not only static environments, but also some dynamic carriers, such as ships and aircraft. So, it has notable advantages and is widely used. The MHM method divides the sky into grids according to the azimuth and elevation angles of satellite, and calculates the average of the residuals within the grid points as its multipath calibration value. It is easy to implement, but it will inevitably lead to excessive or insufficient multipath correction in the grid. The trend surface analysis-based multipath hemispherical map (T-MHM) method makes up for this deficiency by performing trend surface analysis on the multipath spatial changes within the grid points. However, the effectiveness of T-MHM is limited and less capable of resisting noise interference due to the multicollinearity between the independent variables caused by the special spatial distribution of multipath sampling and the overfitting problem caused by ignoring the multipath anisotropy. Thus, we proposed an improved multipath elimination method named AT-MHM (advanced trend surface analysis-based multipath hemispherical model), which cautiously judges the occurrence of the above problems and gives corresponding solutions. This was extended to double-difference mode, which expands the scope of application. The performance of AT-MHM in GPS pseudorange multipath mitigation was verified on geodetic receiver and low-cost receiver in a strong multipath environment with high occlusion. [ABSTRACT FROM AUTHOR]

A systematic experimental study was performed to detect the compaction and permeability properties of multilayered biaxial and quadriaxial preforms under vacuum pressure. Compression response on ply level showed that the degree of nesting between quadriaxial NCF was more pronounced and the nesting deformation mechanism was affected by the interaction with stitch yarns. Owing to the meso-channels in the fibrous structure and the nesting between layers, the in-plane permeability of quadriaxial NCF did not follow an inverse proportion relationship with the fiber volume fraction. To predict the in-plane permeability of multilayered quadriaxial NCFs, unit cell models at a high level of geometrical details were built, including local variations in yarn cross-sections and the nesting deformation between layers. Numerical methods were implemented, and the prediction results were in very good agreement with the experimental data. Besides, the major contributing parameters to the enhancement of the in-plane permeabilities were identified by investigating the correlation between permeability and structural parameters of quadriaxial NCF. The modeling methodology and the principles established can be applied to the design of the quadriaxial NCF fabrics, where the permeability enhancement was evidenced. [ABSTRACT FROM AUTHOR]

Due to population growth, environmental pollution and climate change, the lack of water resources has become a critical factor which threatens sustainable agricultural development. Reasonable irrigation scheduling strategies can reduce the waste of water and enhance agricultural water-use efficiency. In the present study, the decomposition-coordination theory was adopted to analyze the hierarchical canal system. A novel nonlinear multi-level multi-objective optimization model for complex canal systems was established, taking account of the multiple demands from decision makers and realistic factors of canal operation. An interactive method of the technique for order preference using similarity algorithm and genetic algorithm was proposed to solve the developed model. The developed model was successfully applied for the operational strategy making of a canal system located in the arid area of northwest China. The results indicated that the optimization model could help shorten the operational duration by two days, achieve about 26% reduction of irrigation water consumption, and improve the efficiency of water delivery from 0.566 to 0.687. That will be very favorable for the promotion of the agricultural water productivity, the relief of water shortage crisis and the sustainable development of agriculture. The outcomes can provide a wide range of support for decision making and make irrigation decision-making more scientific and systematic. [ABSTRACT FROM AUTHOR]

In this study, an interval quadratic fuzzy dependent-chance programming (IQFDCP) model is proposed for irrigation water management under uncertainty. This model can deal with the interval and fuzzy uncertainties encountered in optimal irrigation water resources allocation problems. It takes optimal credibility level of system revenue as the objective function for addressing the conflict between maximum system revenue and the credibility level of the system revenue. By providing three scenarios of precipitation, the optimal solutions are obtained. The developed model is applied to a case study for irrigation water allocation in Minqin Oasis, Wuwei city, northwest China. This study can help determine how much irrigation water should be allocated to different crops under the maximum credibility level of the system revenue. The optimal solutions can provide a certain credibility level of system revenue corresponding to different scenarios and mitigate the system-failure risk level of water shortages in arid areas. Moreover, because the IQFDCP can objectively reflect the interrelationship among crop irrigation water amount, system revenue, and system-failure risk level, the results are able to provide advices to decision makers for efficiently managing water resources in different scenarios. [ABSTRACT FROM AUTHOR]