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1,525 result(s) for "Zhang, Yanwei"
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A Bibliometric Analysis on Land Degradation: Current Status, Development, and Future Directions
Land degradation is a global issue receiving much attention currently. In order to objectively reveal the research situation of land degradation, bibliometrix and biblioshiny software packages have been used to conduct data mining and quantitative analysis on research papers in the fields of land degradation during 1990–2019 (data update time was 8 April 2019) in the Web of Science core collection database. The results show that: (1) during the past 20 years, the number of papers on land degradation has increased. According to the number of articles, it is divided into four stages: a low-production exploration period, a developmental sprout period, expansion of the promotion period, and a high-yield active period. (2) Land-degradation research covers 93 countries or regions. The top five countries in terms of research volume are China, the United States, the United Kingdom, Germany, and Australia. China, the United States, and the United Kingdom are the most important countries for international cooperation in the field of land degradation. However, cooperation between countries is not very close overall. (3) Land degradation, degradation, desertification, remote sensing, soil erosion, and soil degradation are high-frequency keywords in the field of land degradation in recent years. (4) The research hotspots in the field of land degradation mainly focus on research directions such as restoration and reconstruction of land degradation, and sustainable management of land resources. (5) The themes of various periods in the field of land degradation are diversified, and the evolutionary relationship is complex. There are 15 evolutionary paths with regard to dynamic monitoring of land degradation, environmental governance of land degradation, and responses of land degradation to land-use change. Finally, the paper concludes that the research directions on land degradation in future include the process, mechanism, and effect of land degradation, the application of new technologies, new monitoring methods for land degradation, theory enhancement, methods and models of ecological restoration, reconstruction of degraded land, multidisciplinary integrated system research, constructing a policy guarantee system for the reconstruction of degraded land, and strengthening research on land resource engineering.
Swin-Transformer-Based YOLOv5 for Small-Object Detection in Remote Sensing Images
This study aimed to address the problems of low detection accuracy and inaccurate positioning of small-object detection in remote sensing images. An improved architecture based on the Swin Transformer and YOLOv5 is proposed. First, Complete-IOU (CIOU) was introduced to improve the K-means clustering algorithm, and then an anchor of appropriate size for the dataset was generated. Second, a modified CSPDarknet53 structure combined with Swin Transformer was proposed to retain sufficient global context information and extract more differentiated features through multi-head self-attention. Regarding the path-aggregation neck, a simple and efficient weighted bidirectional feature pyramid network was proposed for effective cross-scale feature fusion. In addition, extra prediction head and new feature fusion layers were added for small objects. Finally, Coordinate Attention (CA) was introduced to the YOLOv5 network to improve the accuracy of small-object features in remote sensing images. Moreover, the effectiveness of the proposed method was demonstrated by several kinds of experiments on the DOTA (Dataset for Object detection in Aerial images). The mean average precision on the DOTA dataset reached 74.7%. Compared with YOLOv5, the proposed method improved the mean average precision (mAP) by 8.9%, which can achieve a higher accuracy of small-object detection in remote sensing images.
The development of all-inorganic CsPbX3 perovskite solar cells
Recently, compared to organic–inorganic hybrid perovskites, all-inorganic perovskite solar receives enormous attention due to excellent capability to resist heat, moisture and ultraviolet light. In addition, the power conversion efficiency (PCE) of all-inorganic cesium lead halide perovskite optoelectronic devices increase rapidly in the last few years. Therefore, the all-inorganic cesium lead halide perovskite (CsPbX3, X = Br, I or their mixture) is supposed to be alternative light-harvesting materials in solar cells. In recent years, with the in-depth study and continuous optimization of the preparation process, the PCE of all-inorganic perovskite solar cells has exceeded 16% up to now. In this review, we introduce the structural and optical properties of CsPbX3 (X = Br, I or their mixture) thin films, in which the phase transition mechanism and the variation of optical band gap with different halide ratios are elaborated in detail. After that, we briefly described the three different architectures of corresponding perovskite solar cell and two kinds of energy band diagram. And simultaneously the most recent research on the progress in CsPbX3 (X = Br, I or their mixture) solar cell device is outlined by this review, which mainly divided into three parts, namely CsPbI3-based solar cells, CsPb(I1−xBrx)3-based solar cells and CsPbBr3-based solar cells. Finally, the stability of all-inorganic perovskite solar cells is also vividly and simply explored.
Measuring the urban land use efficiency of three urban agglomerations in China under carbon emissions
On the basis of DMSP/OLS and NPP-VIIRS night light images, this study realized carbon emission estimations based on the municipal level from 1999 to 2017, compensating for the characteristics of incomplete statistical data and different statistical calibers. On this basis, the epsilon-based measure (EBM) super-efficiency model and the global Malmquist–Luenberger (GML) index are used to measure the urban land use efficiency (ULUE) and urban land total factor productivity (ULTFP) of the three urban agglomerations under the carbon emission constraints from 1999 to 2017. The following conclusions are drawn through research. (1) The correlation coefficient between the total value of night light pixels and energy consumption carbon emissions was relatively high in the three major urban agglomerations during 1999–2017, and they all passed the significance test of 1%. (2) The ULUE of the three major urban agglomerations generally shows a downward trend and then an upward trend, and spatial heterogeneity is obvious. The spatial distribution of the average level of ULUE is Pearl River Delta Urban Agglomeration (PRDUA) > Yangtze River Delta Urban agglomeration (YRDUA) > Beijing–Tianjin–Hebei Urban agglomeration (BTHUA). (3) The ULTFP of the three major urban agglomerations are all showing an increasing trend, but the geometric mean of URTFP in the PRDUA, BTHUA, and YRDUA decreases successively. Technological progress is the main driving force to promote the progress of ULTFP in each urban agglomeration. (4) The kernel density estimation shows a significant gap in ULUE between the three major urban agglomerations in China, and a phenomenon of polarization or multipolarization is observed. The main reason is the hysteresis of technology diffusion.
Type B lactic acidosis associated with diffuse large B-cell lymphoma and the Warburg effect
Type B lactic acidosis is a rare complication of non-tissue perfusion abnormalities caused by solid tumors or hematologic malignancies. Herein, we present the case of a 42-year-old man with type B lactic acidosis and hypoglycemia who was found to have a diffuse large B-cell lymphoma. The cause of lactic acidosis and/or hypoglycemia is thought to be the Warburg effect, which is when the metabolic rate of a rapidly growing malignant tumor is very high and dominated by glycolysis. Systemic damage from type B lactic acidosis can occur when the increased rate of glycolysis exceeds the normal muscle and liver lactic acid clearance rate. The Warburg effect is a rare but serious condition that needs to be recognized, not only in diffuse large B-cell lymphoma, but also in other malignancies. The prognosis of lactic acidosis in patients with malignant tumors is very poor. Currently, effective chemotherapy seems to be the only hope for survival.
Internal iteration gradient estimator based parameter identification for nonlinear sandwich system subject to quantized sensor and friction nonlinearity
This study proposes an internal iteration scalar-innovation gradient estimation method based on multi-innovation theory for a nonlinear sandwich system subject to a quantized sensor and friction nonlinearity. Different from the existing multi-innovation gradient method (MISG ), the proposed method is designed to resolve the existing shortages of the conventional MISG. First, the decomposing method is applied to derive the identification model, and the redundant parameter estimation problem is avoided. Then, an adaptive filter based on the prior knowledge of the system is proposed to obtain the helpful identification data. Second, to solve the multi-innovation length problem in MISG, the internal iteration principle is presented to convert the multi-innovation updating to scalar-innovation updating under a given innovation length, where the positive estimation performance can be achieved. Subsequently, the trigger mechanism is used to produce the suboptimal initial estimate value when the next parameter adaptive law is updated. Then, the fast convergence rate is obtained. Finally, the proposed estimation strategy is verified by conducting a numerical example and an experiment on a practical electromechanical system test bench.
Association between a body shape index and cognitive impairment among US older adults from a cross-sectional survey of the NHANES 2011–2014
Purpose This study aimed to assess the relationship between A Body Shape Index (ABSI) and cognitive impairment among older adults in the United States. Methods This cross-sectional study analyzed cognitive function in 2,752 individuals aged 60 and older using data from the 2011–2014 National Health and Nutrition Examination Survey (NHANES). Cognitive assessments were conducted using the Immediate Recall Test (IRT), Delayed Recall Test (DRT), Animal Fluency Test (AFT), and Digit Symbol Substitution Test (DSST). A Body Shape Index (ABSI) was calculated from waist circumference (WC), weight, and height. The relationship between ABSI and cognitive outcomes was examined through multifactorial linear regression, smooth curve fitting, and subgroup and interaction analyses. Results With complete data, 2752 persons 60 and older participated in the study. After adjusting for covariables, these results showed statistically significant negative relationships between ABSI, IRT, and DSST scores. The negative correlation between DSST and ABSI is more substantial in males than females. There is less of a negative link between ABSI, AFT, and DSST among drinkers who consume 12 or more drinks annually compared to those who consume less. Furthermore, compared to individuals without high blood pressure(HBP), those who suffered HBP showed a more significant negative connection between ABSI and AFT. Conclusion Lower cognitive function was linked to higher ABSI.
Dimethyl Itaconate Alleviates the Inflammatory Responses of Macrophages in Sepsis
AbstractSepsis is an inflammatory disease characterized by dysregulation of inflammation. Macrophage-mediated inflammation has been implicated in the pathophysiology of sepsis. Itaconate is a metabolite produced in activated macrophages which has anti-inflammatory activities. In the present study, we investigated the potential effects of a cell-permeable itaconate derivative dimethyl itaconate on inflammation in sepsis. We established a lipopolysaccharide (LPS)-induced septic mouse model and administered dimethyl itaconate to the septic mice. The survival rate, serum level of pro-inflammatory cytokines, and lung pathology were evaluated. We also administered dimethyl itaconate to LPS-treated bone marrow–derived macrophages (BMDMs), and measured the cytokine production and Nrf2 expression. We also evaluated the effects of dimethyl itaconate on Nrf2-deficient mice. Administration of dimethyl itaconate enhanced survival rate, decreased serum level of TNF-α and IL-6, and ameliorated lung injury in septic mice. Dimethyl itaconate also suppressed LPS-induced production of TNF-α, IL-6, and NOS2 in BMDMs. Dimethyl itaconate activated Nrf2 and promoted the expression of Nrf2 and its downstream factor HO-1 and NQO-1. The regulatory activities of dimethyl itaconate on inflammatory cytokine production, mouse survival rate were abolished in septic Nrf2−/− mice. Dimethyl itaconate suppressed the inflammatory responses of macrophages in sepsis.
Interactive Relationship among Urban Expansion, Economic Development, and Population Growth since the Reform and Opening up in China: An Analysis Based on a Vector Error Correction Model
Based on cointegration analysis, a vector error correction model (VECM), and the impulse response function method, this paper empirically analyses the interaction among urban expansion, economic development, and population growth in China from 1980 to 2016. The results show that (I) there is a long-term equilibrium relationship among urban expansion, economic development and population growth, but there is an imbalance in the short term. When urban expansion deviates from the long-term equilibrium, it cannot be restored to equilibrium in the short term. However, when economic development and population growth deviate from equilibrium, they will adjust back to equilibrium with strengths of −0.1770 and −0.0217, respectively. (II) From the results of the impulse response, there is an interactive statistical relationship between urban expansion, economic development, and population growth; In the short term, both economic development and population growth will cause urban expansion. In the long term, economic development will inhibit urban expansion, and economic development will be less dependent on land. Also, population growth has a long-lasting positive effect on urban expansion. (III) The results of variance decomposition show that urban expansion and economic development were most affected by the structural impact of population growth, and the relative variance contribution (RVC) rate was stable at 29.2% and 42%, respectively. However, economic development contributes the least to the RVC of urban expansion and population growth, and only stabilizes at 12.3% and 8.0% after 30 periods. Finally, the paper proposes that the Chinese government should maintain stable and healthy economic growth and promote sustainable land use in terms of improving land use efficiency, improving human capital levels, and promoting industrial structure.
Nutrients and particulate organic matter discharged by the Changjiang (Yangtze River): Seasonal variations and temporal trends
From September 2009 to August 2010, intensive monthly sampling of nutrients was conducted at two stations at the mouth of the Changjiang (Yangtze River). Particulate organic carbon (POC), particulate nitrogen (PN), and their stable isotope values (δ13C and δ15N) were also measured in selected samples of all months. Most nutrients (nitrate, phosphate, ammonia, and nitrite) as well as POC, PN, and δ13C displayed peak values when the highest or lowest Changjiang monthly discharges occurred, suggesting the Changjiang discharges strongly influence the seasonal variations of these chemicals. The sharply increases in concentrations of ammonia and nitrite in winter probably suggest nitrification was greatly depressed during this cold period. Using five interpolation methods, the annual discharge fluxes of nutrients, POC, and PN from the Changjiang to the East China Sea shelf were calculated. Combining this nutrient data with data from previous studies, the seasonal Mann‐Kendall test, in which the influence of seasonal variation was considered, suggests concentrations of nitrate and phosphate in the Changjiang have significantly increased during recent decades at rates of 2.2μM yr−1 and 0.03 μM yr−1, respectively; no significant trend for silicate was noted. Decreased POC annual fluxes along with sharply decreased suspended particulate matter yields were also seen in recent years (1993–2010). However, no distinct changes of δ13C, δ15N, and the POC/PN ratio, which describe the particulate organic matter properties, were observed during this period. Key Points Seasonal variations of nutrients and POC discharged by Changjiang are described Annual fluxes of nutrients and POC discharged by Changjiang are calculated Temporal trends of nutrients and POC discharged by Changjiang are evaluated