ALBERT

Description: IJERPH, Vol. 15, Pages 1808: Labor Off-Farm Employment and Cropland Abandonment in Rural China: Spatial Distribution and Empirical Analysis International Journal of Environmental Research and Public Health doi: 10.3390/ijerph15091808 Authors: Xin Deng Dingde Xu Yanbin Qi Miao Zeng Alleviating cropland misallocation is helpful for the sustainable development of agriculture. Does off-farm employment inevitably result in cropland misallocation (e.g., cropland abandonment) and threaten the sustainable development of agriculture? This study differs from prior studies in its view that off-farm employment does not necessarily result in cropland abandonment. Specifically, the study employs survey data from 8031 peasant households from 27 provinces in rural China and spatial statistics to analyze the distribution of off-farm employment and cropland abandonment. Empirical models (i.e., IV-Probit and IV-Tobit) are used to examine the quantitative relation between off-farm employment and cropland abandonment. The results are as follows. (1) The spatial distribution of off-farm employment or cropland abandonment differs among regions. Regions with a higher rate of off-farm employment show more cropland abandonment but a lower average area of cropland abandonment. (2) Off-farm employment has a significant and positive correlation with cropland abandonment. However, its square has a significant and negative correlation with cropland abandonment; i.e., there is an inverted U-shaped relationship between off-farm employment and cropland abandonment, with the turning point occurring at 46.00% off-farm employment. (3) Off-farm employment has a significant and positive correlation with the area of cropland abandonment. However, its square has a significant and negative correlation with the area; i.e., there is an inverted U-shaped relationship between off-farm employment and area, with the turning point occurring at 44.50% off-farm employment. This study reveals the relationship between off-farm employment and cropland abandonment and provides policymakers with references for use in developing sustainable agriculture.

Description: In this paper, an innovative inertial navigation system (INS) mechanization and the associated Kalman filter (KF) are developed to implement a fine alignment for the strapdown INS (SINS) on stationary base. The improved mechanization is established in the pseudo-geographic frame, which is rebuilt based on the initial position. The new mechanization eliminates the effects of linear movement errors on the heading by decoupling. Compared with the traditional local-level mechanization, it has more advantages. The proposed algorithm requires lower coarse alignment accuracy in both the open-loop and closed-loop KFs and hence can improve the system reliability and decrease the total alignment time. Moreover, for the closed-loop KF, it can decrease oscillation caused by the system errors and improve the closed-loop system stability. In addition, the proposed algorithm can also be applied to polar alignment. The performance of the proposed algorithm is verified by both simulations and experiments and the results exhibit the superior performance of the proposed approach.

Description: Sensors, Vol. 18, Pages 2952: An Autonomous Vehicle Navigation System Based on Inertial and Visual Sensors Sensors doi: 10.3390/s18092952 Authors: Xingxing Guang Yanbin Gao Henry Leung Pan Liu Guangchun Li The strapdown inertial navigation system (SINS) is widely used in autonomous vehicles. However, the random drift error of gyroscope leads to serious accumulated navigation errors during long continuous operation of SINS alone. In this paper, we propose to combine the Inertial Measurement Unit (IMU) data with the line feature parameters from a camera to improve the navigation accuracy. The proposed method can also maintain the autonomy of the navigation system. Experimental results show that the proposed inertial-visual navigation system can mitigate the SINS drift and improve the accuracy, stability, and reliability of the navigation system.

Description: Sustainability, Vol. 10, Pages 1469: Exploration of the Industrial Spatial Linkages in Urban Agglomerations: A Case of Urban Agglomeration in the Middle Reaches of the Yangtze River, China Sustainability doi: 10.3390/su10051469 Authors: Yan Yu Qianwen Han Wenwu Tang Yanbin Yuan Yan Tong The study of industrial spatial linkages of urban agglomerations is crucial to recognizing spatial structure and optimizing regional division and cooperation. The existing studies often focus on external spatial interaction at the inter-city level, but few have considered complex internal economic linkages at the inter-sector level. In this study, we established an integrated framework by combining the wave effect gradient field with the gravity model. The wave effect gradient field was used to analyze the inter-sector relation, while the gravity model was adopted to explore the spatial interactions of industry at the inter-city level. The Urban Agglomeration in the Middle Reaches of the Yangtze River (UAMRYR) was taken as a case study, which demonstrates the applicability of the proposed framework. The results indicate that there exists an imbalanced development in the network of industrial linkages in the study region. Each subgroup has presented a self-organized spatial linkage network, but the linkages between subgroups are immature. Compared with other sectors, the high-tech and internet industrial sectors contribute most to economic linkages among cities. Thus, policymakers should take actions to strengthen the inter-subgroup spatial linkages and give priority to the high-tech industries, which is necessary for the integrated and sustainable development of UAMRYR.

Description: IJERPH, Vol. 14, Pages 970: Occurrence, Distribution, and Risk Assessment of Perfluoroalkyl Acids (PFAAs) in Muscle and Liver of Cattle in Xinjiang, China International Journal of Environmental Research and Public Health doi: 10.3390/ijerph14090970 Authors: Gehui Wang Jianjiang Lu Zhenni Xing Shanman Li Zilong Liu Yanbin Tong Despite risks associated with perfluoroalkyl acids (PFAAs) in many regions, little is known about their prevalence in Xinjiang. We determined the presence of 13 PFAAs in 293 beef muscle and liver samples collected in 22 cities covering northern, southern, and eastern Xinjiang using liquid chromatography, coupled with tandem mass spectrometry. Overall, the average values for PFAAs were relatively low compared with previous studies. Liver presented higher mean levels of total PFAAs at 1.632 ng/g, which was over 60-fold higher than in muscle (0.026 ng/g). Among the PFAAs analyzed, medium-chain compounds were dominant, accounting for more than 70% of the total. Perfluorooctane sulfonate (PFOS) was highly prevalent in the liver with the highest mean concentration (0.617 ng/g) and detection frequency (80%). When comparing the three regions of Xinjiang, we found differences in PFAA profiles, with the northern region showing the highest levels. Furthermore, the average daily intake and hazard ratios of PFOS and perfluorooctanoic acid varied by region, urban/rural environment, gender, ethnicity, and age. The highest risk value of 13 PFAAs was estimated to be 0.837 × 10−3, which is far below 1, indicating that there is no health risk posed by eating beef muscle and liver in Xinjiang.

Description: Sensors, Vol. 17, Pages 1973: A Portable Impedance Immunosensing System for Rapid Detection of Salmonella Typhimurium Sensors doi: 10.3390/s17091973 Authors: Tao Wen Ronghui Wang America Sotero Yanbin Li Salmonella Typhimurium is one of the most dangerous foodborne pathogens and poses a significant threat to human health. The objective of this study was to develop a portable impedance immunosensing system for rapid and sensitive detection of S. Typhimurium in poultry. The developed portable impedance immunosensing system consisted of a gold interdigitated array microelectrode (IDAM), a signal acquisitive interface and a laptop computer with LabVIEW software. The IDAM was first functionalized with 16-Mercaptohexadecanoic acid, and streptavidin was immobilized onto the electrode surface through covalent bonding. Then, biotin-labelled S. Typhimurium-antibody was immobilized onto the IDAM surface. Samples were dropped on the surface of the IDAM and the S. Typhimurium cells in the samples were captured by the antibody on the IDAM. This resulted in impedance changes that were measured and displayed with the LabVIEW software. An equivalent circuit of the immunosensor demonstrated that the largest change in impedance was due to the electron-transfer resistance. The equivalent circuit showed an increase of 35% for the electron-transfer resistance value compared to the negative control. The calibration result indicated that the portable impedance immunosensing system could be used to measure the standard impedance elements, and it had a maximum error of measurement of approximately 13%. For pure culture detection, the system had a linear relationship between the impedance change and the logarithmic value of S. Typhimurium cells ranging from 76 to 7.6 × 106 CFU (colony-forming unit) (50 μL)−1. The immunosensor also had a correlation coefficient of 0.98, and a high specificity for detection of S. Typhimurium cells with a limit of detection (LOD) of 102 CFU (50 μL)−1. The detection time from the moment a sample was introduced to the display of the results was 1 h. To conclude, the portable impedance immunosensing system for detection of S. Typhimurium achieved an LOD that is comparable with commercial electrochemical impedance instruments. The developed impedance immunosensor has advantages in portability, low cost, rapid detection and label-free features showing a great potential for in-field detection of foodborne pathogens.

Description: Materials, Vol. 10, Pages 1091: Effects of Pulse Parameters on Weld Microstructure and Mechanical Properties of Extra Pulse Current Aided Laser Welded 2219 Aluminum Alloy Joints Materials doi: 10.3390/ma10091091 Authors: Xinge Zhang Liqun Li Yanbin Chen Zhaojun Yang Yanli Chen Xinjian Guo In order to expand the application range of laser welding and improve weld quality, an extra pulse current was used to aid laser-welded 2219 aluminum alloy, and the effects of pulse current parameters on the weld microstructure and mechanical properties were investigated. The effect mechanisms of the pulse current interactions with the weld pool were evaluated. The results indicated that the coarse dendritic structure in the weld zone changed to a fine equiaxed structure using an extra pulse current, and the pulse parameters, including medium peak current, relatively high pulse frequency, and low pulse duty ratio benefited to improving the weld structure. The effect mechanisms of the pulse current were mainly ascribed to the magnetic pinch effect, thermal effect, and electromigration effect caused by the pulse current. The effect of the pulse parameters on the mechanical properties of welded joints were consistent with that of the weld microstructure. The tensile strength and elongation of the optimal pulse current-aided laser-welded joint increased by 16.4% and 105%, respectively, compared with autogenous laser welding.

Description: Minerals, Vol. 7, Pages 151: Vertical Heterogeneity of the Shale Reservoir in the Lower Silurian Longmaxi Formation: Analogy between the Southeastern and Northeastern Sichuan Basin, SW China Minerals doi: 10.3390/min7080151 Authors: Jun Liu Yanbin Yao Derek Elsworth Dameng Liu Yidong Cai Li Dong Lower Silurian Longmaxi formation (LSL) shale is widely and continuously distributed in the northeastern Sichuan Basin and, based on structural analogies with the gas producing LSL formation in the southeastern Sichuan Basin, has significant potential for shale gas exploration. However, limited research has been performed to evaluate the shale gas potential in this region. Samples from a recently completed exploratory well (Well-WQ2) in the northeastern Sichuan Basin indicate that the LSL shale has a vertical property sequence that closely resembles the vertical property sequences in wells in the gas-producing sections of the southeastern Sichuan Basin. The continuous sampling and analyses of Well-WQ2 have allowed a detailed investigation of the vertical variations in lithofacies, mineral characteristics, pore structures, and organic geochemical characteristics. The Longmaxi formation was divided into two third-order sequences (SQ1 and SQ2) based on systematic core observations and well logging analyses. Both SQ1 and SQ2 include a transgressive system tract (TST) and a high-stand system tract (HST). The lithofacies exhibit an upward decrease in the organic content. From SQ1 to SQ2, the quartz content, in situ graptolite content, total organic carbon (TOC) content, and brittleness index decrease, but the clay mineral content increases. The LSL shale sections from depths of 1204 to 1214 m and from 1271 to 1282 m possess well-developed fractures and high permeability. Additionally, the average porosity and permeability in SQ1 are higher than those in SQ2. In addition, the positive correlation between the TOC and quartz contents of the assayed samples suggests that much of the quartz is of biogenic origin. Changes in the sedimentary and diagenetic environments during deposition are two key factors that contribute to the observed vertical heterogeneity of the Longmaxi formation. In conclusion, the shale sections of the lower part of the SQ1, like their analogs in the southeastern Sichuan Basin, are the most favorable targets for shale gas production in the northeastern Sichuan Basin.

Description: Peatlands play an important role in the global carbon cycle and potentially have a significant impact on regional climate change. Restoring and rewetting the degraded peatlands is an urgent task. However, effects of rewetting on the carbon emissions of peatlands remain poorly understood. In this study, the process of rewetting a piece of the degraded Zoige alpine peatland was experimentally simulated and the derived results were compared with those of natural rewetting by monitoring CO2 and CH4 fluxes and other environmental factors before and after rewetting. The natural rewetting results showed that rewetting decreased ecosystem respiration (ER) by about 60%. Furthermore, rewetting increased CH4 emissions by 127%, decreased total carbon emissions (TCE) from 270 to 157 mg CO2 m−2 h−1, and decreased TCE from the entire ecosystem by 42%. The results of the controlled experiment showed that ER decreased gradually as the degree of rewetting was increased, and CH4 fluxes and changes in water level were significantly and positively correlated: CH4 fluxes increased from 0.3 (water level −20 cm) to 2.17 mg CH4 m−2 h−1 (water level 20 cm). After rewetting, the TCE of the whole ecosystem were significantly decreased. Regional observations showed that CO2 fluxes were significantly and negatively correlated to the water level; and the corresponding CO2 equivalent was significantly and positively correlated to the water level, while TCE were significantly and negatively correlated to the water level. Our findings indicate that rewetting can decrease carbon emissions and thus contribute in mitigating the adverse effects of climate change in alpine peatland.

Description: An accurate initial alignment must be required for inertial navigation system (INS). The performance of initial alignment directly affects the following navigation accuracy. However, the rapid convergence of meridians and the small horizontalcomponent of rotation of Earth make the traditional alignment methods ineffective in polar regions. In this paper, from the perspective of global inertial navigation, a novel alignment algorithm based on pseudo-Earth frame and backward process is proposed to implement the initial alignment in polar regions. Considering that an accurate coarse alignment of azimuth is difficult to obtain in polar regions, the dynamic error modeling with large azimuth misalignment angle is designed. At the end of alignment phase, the strapdown attitude matrix relative to local geographic frame is obtained without influence of position errors and cumbersome computation. As a result, it would be more convenient to access the following polar navigation system. Then, it is also expected to unify the polar alignment algorithm as much as possible, thereby further unifying the form of external reference information. Finally, semi-physical static simulation and in-motion tests with large azimuth misalignment angle assisted by unscented Kalman filter (UKF) validate the effectiveness of the proposed method.