Areas Of Southwest China Research Articles

Disastrous Mechanism of Water Burst by Karst Roof Channel in Rocky Desertification Mining Area in Southwest China

With the development of coal mining in rocky desertification mining area in Southwest China, water burst is becoming an important disaster in coal mine. In order to grasp the evolution characteristics of water gushing channels in coal mining in rocky desertification mining area, the 1402 working face in Xintian Coal Mine is taken as the research object, and the occurrence of aquifers on the roof of the working face is analyzed, and the water filling path of the aquifers is explored. Besides, the evolution characteristics of water passage in coal seam mining are comprehensively analyzed, by the methods of physical similarity simulation, numerical simulation, and microseismic monitoring. The results show that the key water resource is the atmospheric precipitation, which enters the mine through the original karst fissure and mining-induced fissure. With the continuous advance of working face, the fracture height of overburden increases gradually. Specifically, when the advancement distance of working face exceeds 135 m, the water-conducting cracks in the overlying strata develop to the bottom boundary of the Yulongshan limestone aquifer, and then, the mining-induced fracture and aquifer are conducted; when the working face advances 190 m, the overall overburden mining fissure is divided into fissure opening zone and fissure closed zone. Meanwhile, most of the microseismic events occur in the middle part of the karst roof, and the maximum height of microseismic event is 40 m away from the bottom boundary of the Yulongshan limestone, during the advancing process of the working face. When the mining fissure is connected with the original karst fissure, atmospheric precipitation enters the aquifer through the original karst fissure and enters the gob of working face through the mining fissure. The research results provide the references for prediction and prevention for the water burst disaster in rocky desertification mining area in Southwest China.

A preliminary study on soil radon anomaly and its formation mechanism in karst area of southwest China

A preliminary study on soil radon anomaly and its formation mechanism in karst area of southwest China

Full-scale Fire Experiment of Timber Buildings in Rural Areas of Southwest China

ABSTRACT Many cultural and heritage structures are constructed using timber materials in China. Timber buildings are very common in historic and cultural blocks and rural areas of Southwest China. Many of them have been destroyed during fire and exert an inestimable loss to people and society. This work is aimed at investigating the temperature distribution, flame and smoke behavior within timber compartments. A full-scale experiment was built and carried out. The timber building groups consist of four compartments placed in two platforms of different heights. Temperature profiles were obtained by thermocouples arranged at corresponding positions. Fire behavior both in and out of compartments, as well as structural failure, were examined. A smoke detection system was applied to record the arrival time of smoke at a specific position. Cameras were also employed to observe and record the fire growth. The potential route of smoke is revealed. The results suggest that not only the common route of smoke should be taken into consideration in designing smoke detection systems but also the unconventional path of the gaps. The obtained data of temperature profiles will provide useful information for the prevention of historic and cultural timber buildings in Southwest China.

Response of surface-soil quality to secondary succession in karst areas in Southwest China: Case study on a limestone slope

Karst areas are fragile ecological environments facing serious soil quality problems. It is crucial to understand the surface-soil quality for ensuring the secondary succession of vegetation. In this study, four plots located on the same hill slope were selected, representing the four secondary succession stages of arable land, grassland, shrubs, and secondary forest, respectively. The surface-soil quality during secondary succession is assessed using the minimum dataset method. The results show that secondary succession decreased soil bulk density and total potassium content (P < 0.05), whereas soil organic matter, saturated hydraulic conductivity, overall porosity, and total nitrogen increased (P < 0.05). However, pH and capillary porosity are relatively stable. Non-capillary porosity and total phosphorus content first decreased and then increased. In addition, the mean soil quality indices increased and the difference in surface-soil quality between stages decreased with vegetation succession (P < 0.05). Improvement in surface-soil quality is most obvious in the early stages of secondary succession, and natural vegetation restoration can solve the land degradation problem. This study is not only helpful in understanding the changes in surface-soil quality during the secondary succession but also provides a theoretical basis for selecting ecological restoration methods in karst regions.

Hydrochemical characteristics and health risk assessment of groundwater in karst areas of southwest China: A case study of Bama, Guangxi

The southwest karst area is considered to have the most vulnerable groundwater environment in China. Groundwater quality is an important factor restricting sustainable economic development. In this study, traditional water chemistry method, water quality index (WQI), and hazard index (HI) were applied to comparatively analyze the hydrochemical characteristics of groundwater and the water quality in the exposed karst region (EKR) and buried karst region (BKR) in Bama, a typical karst area in southwest China. Generally, the main water type was Ca/Mg–HCO3. Due to the predominance of dissolution of carbonate rocks in EKR and silicate rocks in BKR, higher total dissolved solids (TDS), Ca and HCO3− concentrations, and lower H2SiO3 content were detected in groundwater in EKR compared with BKR. As affected by weathering of rocks such as lead-zinc ore, the maximum concentrations of Zn and Sr were 11.23 mg/L and 13.30 mg/L, showing that mineral water resources are widely distributed in Bama. The ion ratios and isotope abundances (δD and δ18O) in groundwater samples indicated stronger evaporation and rock-water interaction in EKR than BKR. Human activities exerted a more significant influence on the water quality in EKR compared to BKR. The mean WQI value also suggested that the groundwater quality was better in BKR (9.56) than EKR (12.17). Although 95.7% of the water samples in the study area were classified as excellent based on their WQI values, 4.3% of the water samples still had significant health risks (HI > 1) due to the high Sb, Zn, As, and Sr concentrations. It is recommended to reduce anthropogenic pollution in EKR and develop a plan for clean production of mineral water industry according to local conditions, which will help the sustainable development of the local economy.

Spatio-Temporal Variation of Vegetation Ecological Quality and Its Response to Climate Change in Rocky Desertification Areas in Southwest China during 2000–2020

Vegetation restoration is the primary task of ecological reconstruction and rocky desertification control in Karst areas. With vegetation net primary productivity and coverage as two key indicators, a vegetation ecological quality evaluation model was built based on meteorological and remote sensing data. Spatiotemporal variation of vegetation ecological quality index and its response to climate change in rocky desertification areas in Southwest China during 2000–2020 were also analyzed by using the difference method and linear trend method. The results showed that: (1) Vegetation ecological quality in rocky desertification areas in Southwest China showed a fluctuating upward trend during 2000–2020. In 2020, the vegetation ecological quality index reached 69.7, which was 19.9% and 9.3% higher than the averaged values for 2000 and 2000–2019, respectively, ranking the fourth highest since 2000. (2) Vegetation ecological quality of the rocky desertification areas in Yunnan, Guangxi and Guizhou provinces have been improved by 89.2%, 99.2% and 98.5%, respectively, from 2000 to 2020, with their vegetation ecological quality index values increasing by 0.5–0.75 per year in southeast Yunnan, most areas in Guizhou and northwest Guangxi. (3) Precipitation was an important meteorological factor affecting the vegetation ecological quality in rocky desertification areas. The vegetation ecological quality index in the northwest and central Yunnan rocky desertification areas has been rising slowly, but with localized declines at a yearly rate of nearly 0.25 caused by climatic warming and drying.

Protective Effects of Appropriate Amount of Nuts Intake on Childhood Blood Pressure Level: A Cross-Sectional Study.

ObjectiveIncreased blood pressure (BP) is a major risk factor for cardiovascular disease (CVD) in adults. Regular consumption of nuts may improve some BP in adults whereas evidence in children is relatively lacking. This study aimed to determine the efficacy of nuts intake on BP in children.MethodsStratified cluster sampling was performed to include a total of 15,268 primary school children aged 6–12 years in urban and rural areas in Southwest China. The daily nuts intake dosage was collected by questionnaires, and generalized linear model (GLM) and logistic regression were used to analyze the relationship between nuts intake and BP.ResultsFor the total subjects, 11,130 (72.9%) participants consumed <35 g/day of nuts, 1,145 (7.5%) participants consumed 35 g/day ≤ nut <50 g/day of nuts, 2,053 (13.4%) participants consumed 50~100 g/day of nuts, and 940 (6.2%) participants consumed over 100 g/day of nut. For sex subgroup, 1,074 (13.53%) boys and 979 (13.35%) girls consumed 50~100 g/day of nuts. Compared with the 50~100 g/day of nuts intake group, systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) were significantly different in <35 g/day, 35g/day ≤ nut <50 g/day, and >100 g/day nuts intake groups (all p < 0.001). The logistic regression showed that compared with the 50~100 g/day group, the other three groups are more likely associated with childhood hypertension (all p < 0.001). Therefore, a U-shaped relationship between nuts intake and BP level was identified.ConclusionsThe finding suggests that intake of 50~100 g/day nuts is the recommended dose of nuts intake to control childhood hypertension, as well as for cardioprotection purposes.

Classifying Forest Types over a Mountainous Area in Southwest China with Landsat Data Composites and Multiple Environmental Factors

Accurate information about forest type and distribution is critical for many scientific applications. It is possible to make a forest type map from the satellite data in a cost effective way. However, forest type mapping over a large and mountainous geographic area is still challenging, due to complex forest type compositions, spectral similarity among various forest types, poor quality images with clouds or cloud shadows and difficulties in managing and processing large amount data. Based on the Google Earth Engine (GEE) cloud platform, a method of forest types mapping using Landsat-8 OLI imagery and multiple environmental factors was developed and tested within Yunnan Province (about 390,000 km2) of China. The proposed approach employed a pixel-based seasonal image compositing method to produce two types of seasonal composite images, i.e., four 7-spectral-band composite images and four 5-VI-band composite images associated in spring, summer, autumn, and winter. Then, single-season feature bands and multi-seasonal feature bands were combined with the feature bands of topography, temperature, and precipitation, respectively, and resulting in 17 feature combinations. Finally, using a random forest (RF) classifier, 17 feature combinations were separately experimented to classify the forest type over the study area. The study area was firstly classified into the forest and the non-forest, and then the forest was sub-classified into five forest types (evergreen needleleaf forest, deciduous needleleaf forest, evergreen broadleaf forest, deciduous broadleaf forest, and mixed forest). The results showed that the pixel-based multi-seasonal median composite can produce a cloud-free image for the entire region and is suitable for forest type mapping. Compared with a single-season composite, a multi-seasonal composite can distinguish different forest types more effectively. The environmental factors also improve the accuracy of forest type mapping. With the ground survey samples as reference values, the classification performance of 17 feature combinations was compared, and the optimal feature combination was found out. For the optimal feature combination, its overall accuracy of the forest/non-forest cover map and the forest type map reached 97.57% (Kappa = 0.950) and 70.30% (Kappa = 0.628), respectively. The proposed approach has demonstrated strong potential of high classification accuracy and convenient calculation when mapping forest types over a national or global scale, and its product of 30 m resolution forest type map is capable of contributing to forest resource management.

Problem Posing and Its Relationship with Teaching Experience of Elementary School Mathematics Teachers from Ethnic Minority Area in Southwest China

This study examined characteristics of problem posing and its relationship with the teaching experience of elementary school mathematics teachers from ethnic minority areas in the Southwest of China. Eighty-one (N = 81) elementary school mathematics teachers responded to a task-based questionnaire and posed mathematical problems based on given problem situations. Characteristics of their mathematical problem posing were observed through the total numbers, appropriateness, difficultly, and flexibility levels of the problems posed by the teachers. Results show that elementary school mathematics teachers were capable of posing a considerable number of appropriate mathematical problems. Significant differences were found in the flexibility of the posed problems among the teachers with different years of teaching experience. This finding suggests that teachers’ capability in mathematical problem posing may not necessarily grow along with teaching experience. Limitations of the study and implications in developing teachers’ mathematical problem posing are discussed.

Atmospheric VOCs Pollution Characteristics and Health Risk Assessment of Large-scale Integrated Industrial Area and Surrounding Areas in Southwest China

To investigate the characteristics of atmospheric volatile organic compound (VOCs) pollution and promote VOCs pollution prevention and control in industrial areas, in December 2020, VOCs samples collected using Summa Canisters at three observation sites were used to study the characteristics of VOCs pollution and source apportionment and to conduct a health risk assessment in large integrated industrial areas and surrounding urban areas in southwest China. The results showed that the mean φ(TVOCs) at site A and site B in an industrial area and at a third urban site were 105.25×10-9, 222.92×10-9, and 82.87×10-9, respectively. Monochloromethane, dichloromethane, acetone, ethanol, and ethane were the species with higher volume fractions at the three sites. Aromatic hydrocarbons and OVOCs had a large contribution to the ozone formation potential (OFP), with a cumulative contribution of more than 50%, and the main reactive species were methyl methacrylate, toluene, p-xylene, and o-xylene; the secondary organic aerosol formation potential (SOAP) of aromatic hydrocarbons contributed more than 80%, with the main active species being toluene, p-xylene, and o-xylene. The results of PMF source analysis showed six main sources of VOCs, in the descending order of the petrochemical industry (21.83%), industrial waste incineration (18.6%), pharmaceutical manufacturing (16.99%), fossil fuel combustion (16.03%), motor vehicle exhaust (14.23%), and chemical manufacturing (12.32%). The mean values of the hazard index (HI) of site A and site B in the industrial area and in the urban site were 0.55, 0.68, and 0.41, respectively, and the mean lifetime cancer risk (LCR) values were 6.71×10-6, 6.72×10-6, and 6.58×10-6, respectively. Both HI and LCR in industrial areas were larger than those in urban areas. The quantitative assessment of risk sources showed that motor vehicle exhaust and fossil fuel combustion contributed relatively high carcinogenic risks.

引种降香黄檀和顶果木对石漠化山区土壤磷素转化及其有效性的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 引种降香黄檀和顶果木对石漠化山区土壤磷素转化及其有效性的影响 DOI: 10.5846/stxb202012223252 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（31960240）；广西自然科学基金项目（2017GXNSFAA198207，2018GXNSFAA294139，2019GXNSFAA185023） Effects of introducing Dalbergia odorifera and Acricarpus fraxinifolius on soil phosphorus transformation and availability in rocky desertification mountainous regions Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:我国西南岩溶区石漠化严重，植被覆盖率低，土壤贫瘠。植被恢复作为一项重要的生态治理措施，在提高土壤养分有效性，增加生物多样性和改善生态环境等方面发挥着极其重要的作用。以广西马山县经过8年植被恢复的4种样地类型（降香黄檀纯林；顶果木纯林；降香黄檀/顶果木混交林；相邻的天然灌草丛作为对照组）为研究对象，探讨了引进固氮树种（降香黄檀和顶果木）及其种植模式对石漠化山区土壤磷素转化及其有效性的影响。研究结果表明：（1）降香黄檀/顶果木混交林土壤的有机质（SOM）、硝态氮（NO3--N）、有效磷（AP）、微生物生物量碳（MBC）、微生物生物量氮（MBN）和微生物生物量磷（MBP）含量均显著高于对照（P<0.05）；降香黄檀/顶果木混交林、顶果木纯林和降香黄檀纯林的全磷（TP）相比于对照组更易转化为AP，其中以降香黄檀/顶果木混交林的效果最佳。（2）相关分析结果表明，土壤NH4+-N、NO3--N和MBN与AP分别呈显著线性正相关（P<0.05），MBN与MBP呈极显著线性正相关（P<0.01）。（3）引种降香黄檀和顶果木后，各林分的土壤无机磷组分均发生变化，其中降香黄檀/顶果木混交林和顶果木纯林的各种无机磷含量显著增加（P<0.05）。（4）最后，冗余分析表明MBP、SOM和MBN可能是影响土壤无机磷组分变化的最主要因素（P<0.05）。研究表明降香黄檀和顶果木在一定程度上能改善石漠化山区土壤的养分状况和提高土壤磷的有效性，其中以二者混交种植模式的效果最显著，以期为珍贵固氮树种在石漠化生态恢复与重建中的推广应用提供理论依据和实践支持。 Abstract:Rocky desertification is serious in karst areas in southwest China, with low vegetation coverage and poor soil. As an important ecological management measure, vegetation restoration plays an extremely important role in improving the availability of soil nutrients, increasing biodiversity, and improving the ecological environment. In this study, four types of site (the pure plantation of Dalbergia odorifera; the pure plantation of Acricarpus fraxinifolius; the mixed plantation of D. odorifera and A. fraxinifolius; the adjacent natural weed field as the control) in Mashan, Guangxi were selected as the research objects after 8 years of vegetation restoration. The effects of introducing N2-fixing tree species (D. odorifera and A. fraxinifolius) and their planting patterns on the soil phosphorus transformation and availability in rocky desertification mountainous regions were discussed. The results showed that:(1) the contents of soil organic matter (SOM), nitrate nitrogen (NO3--N), available phosphorus (AP), soil microbial biomass carbon (MBC), soil microbial biomass nitrogen (MBN), and soil microbial biomass phosphorus (MBP) in the mixed plantation of D. odorifera and A. fraxinifolius were significantly higher than those of the control (P<0.05). The total phosphorus (TP) of the mixed plantation of D. odorifera and A. fraxinifolius, the pure plantation of A. fraxinifolius and the pure plantation of D. odorifera could be easily transformed into AP than control, among which the mixed plantation of D. odorifera and A. fraxinifolius had the best effect. (2) The results of correlation analysis showed that NH4+-N, NO3--N, and MBN had significant linear positive correlation with AP respectively (P<0.05), while MBN and MBP had extremely significant linear positive correlation (P<0.01). (3) After introducing D. odorifera and A. fraxinifolius, the soil inorganic phosphorus fractions in all sites changed, and the contents of various inorganic phosphorus in the mixed plantation of D. odorifera and A. fraxinifolius and the pure plantation of A. fraxinifolius increased significantly (P<0.05). (4) Finally, the redundancy analysis (RDA) indicated that MBP, SOM, and MBN would be the main factors affecting the changes of soil inorganic phosphorus fractions (P<0.05). Overall, D. odorifera and A. fraxinifolius could improve soil nutrient and phosphorus availability in rocky desertification mountain regions to a certain extent, among which the mixed planting pattern (the mixed plantation of D. odorifera and A. fraxinifolius) had the most significant effect. The purpose of the study could provide theoretical basis and practical support for the application of N2-fixing tree species in the ecological restoration and reconstruction of rocky desertification. 参考文献 相似文献 引证文献

Identification of Sources and Their Potential Health Risk of Potential Toxic Elements in Soils from a Mercury-Thallium Polymetallic Mining Area in Southwest China: Insight from Mercury Isotopes and Pmf Model

Identification of Sources and Their Potential Health Risk of Potential Toxic Elements in Soils from a Mercury-Thallium Polymetallic Mining Area in Southwest China: Insight from Mercury Isotopes and Pmf Model

Limited Co-Benefits of Protected Areas in Southwest China Under Current Climate Change and Human Modification

Limited Co-Benefits of Protected Areas in Southwest China Under Current Climate Change and Human Modification

Heavy metals exposure is associated with early liver dysfunction among rural residents aged 40-75 years in southwest China.

Heavy metals exposure has been associated with liver dysfunction in recent reports, while the hepatoxicity of lead (Pb) and cadmium (Cd) has been well established. However, the combined effects of multi-metal in real-world scenario on liver dysfunction are still unclear. This cross-sectional study examined associations between 10 biomarkers of early liver injury and multiple heavy metals levels. The levels of heavy metals/metalloid (magnesium [Mg], calcium [Ca], iron [Fe], zinc [Zn], arsenic [As], Cd, copper [Cu], and Pb) were measured in blood and urinary sample collected from 725 participants in a Cd-polluted area and an unpolluted area in southwest China. The early liver dysfunction biomarkers included the liver enzymes (ALT, ALP, AST, and GGT), proteins (TP, ALB, and GLO), and bilirubin (TBIL, DBIL, and IBIL). Confounder-adjusted beta coefficients were determined using multiple linear regression model analysis for the group-classified and gender-classified samples. Our results showed that blood Fe, Cd, and Cu levels were found to be positively related to elevated ALT levels and blood Cu was positively associated with AST levels in the Cd-polluted area, while the highest blood Zn quartile in the polluted area and blood Mg quartile in the unpolluted area were associated with lower ALT levels. Our finding implies that industrial pollution results in heavy metals of Cd and Pb exposure and effects of Fe, Cd, Cu, and Pb in the Cd-polluted area may be the main contributors to increase the risk of liver dysfunction while Zn in the Cd-polluted area and Mg in the unpolluted area may be the protective factors.

The impact of childhood parental loss on risk for depression and anxiety in adulthood: A community-based study in Southwest China

PurposeLack of parental raising is an important reason for parental loss in China due to urbanization. We aimed to explore the association between parental loss (including parental death, divorce, alcoholism, crime, drug addiction, bedridden, and lack of parental raising) before 17 years old and mental health disorders in adulthood in Southwest China. MethodsChildhood parental loss, age, gender, socioeconomic status, smoking, drinking, and medical history were self-reported. Patient Health Questionnaire 9 (PHQ–9) and Generalized Anxiety Disorder 7 (GAD-7) were used for identifying depression and anxiety, respectively. We use logistic regression with inverse probability weighting according to the propensity score to assess the risk of childhood parental loss on mental health disorders in adulthood. ResultsA total of 8014 adults were enrolled in this study. Childhood parental loss increased the risk of adulthood depression (OR, 1.60, 95%CI, 1.30–1.98) but not anxiety (p= 0.07) after adjustment of all covariates. Sensitivity analyses including logistic regression with original data, nearest neighbor matching, full matching, and propensity score as the only covariate all yielded similar results. LimitationsRecall bias could not be fully eliminated due to the retrospective nature of study design. Our study had been conducted in a less-prosperous area in Southwest China and the results may not be representative at nation level. ConclusionsChildhood parental loss was associated with depression in adulthood in Southwest China, highlighting the need for early intervention in children with parental loss, to prevent long-term negative effects on their mental health.

Distribution characteristics and potential pollution assessment of heavy metals (Cd, Pb, Zn) in reservoir sediments from a historical artisanal zinc smelting area in Southwest China.

Reservoir sediment contamination with heavy metals produced by mining activities has aroused widespread global concern owing to its potential threat to human health. In this study, the total concentrations and speciation of heavy metals (Cd, Pb, Zn) in the Lexi (LX) and Maoshui (MS) reservoirs around the historical artisanal zinc smelting area in Southwest China were determined, and pollution indices were applied to assess the pollution levels and potential ecological risks of the two reservoirs. The results showed that all the detected samples in the two reservoirs presented significant metal accumulation, especially for Cd, as compared with the soil background values in Guizhou Province. Between the two reservoirs, the vertical distribution characteristics of each metal in sediment columns were similar. The heavy metal concentrations of the three columns in the LX reservoir reached their maxima at 35, 15, and 10cm and showed a trend of first increasing and then decreasing overall. However, the heavy metal contents of the three columns in the MS reservoir all exhibited wave-like characteristics in the vertical direction, and all of them reached a relatively obvious high point at approximately 5 and 30cm. The geoaccumulation index (Igeo) and potential ecological risk index (RI) indicated that Cd was strongly enriched and represented the main risk factor, and the pollution level of the MS reservoir was significantly higher than that of the LX reservoir. Furthermore, the effect coefficients (ERMQ) confirmed that the two reservoirs are likely to have toxic impacts on aquatic organisms and need to be controlled and mitigated. The speciation analysis of heavy metals revealed that Cd was primarily in the acid-extractable fraction (69.57%, 68.28%), Pb was chiefly in the reducible fraction (55.24%, 42.18%) and oxidizable fraction (22.60%, 38.02%), and Zn was mainly in the oxidizable fraction (32.54%, 37.65%) in the LX and MS reservoirs, respectively. The ratios of the secondary phase and primary phase (RSP) and risk assessment code (RAC) evaluation demonstrated that Cd in the sediments of the two reservoirs presents a very high potential ecological risk, and Pb and Zn were at medium to high ecological risk levels. This study highlighted that the artisanal zinc smelting activities had caused serious heavy metal pollution in reservoir sediments, posing a threat to the local ecological environment.

Predicting Upper Secondary School Students’ Programming Self-efficacy in Tobacco Growing Areas of Southwest China Using Decision Tree Analysis

Background: In the field of artificial intelligence, programming self-efficacy plays an indispensable role in the success of programming learning. However, how to predict the level of students’ programming self-efficacy has not been addressed. Objective: To predict the level of programming self-efficacy among upper secondary school students in tobacco growing areas of Southwest China, this study used survey data to develop a decision tree model. Methods: First, a total of 512 questionnaires were collected by using the Academic Achievement Test, Creative Style Scale, Programming Learning Attitude Questionnaire, Motivation Scale, Higher-order Thinking Preferences Scale, and Programming Self-efficacy Scale. Secondly, a decision tree model was constructed by SPSS modeler 18.0. Results: The results showed that academic achievement, creativity style, programming learning, motivation, and higher-order thinking propensity were highly predictive of programming self-efficacy. Conclusions: This is the first study in the direction of educational technology and it represents a novel approach to predicting programming self-efficacy among upper secondary school students. The experimental analysis demonstrate that the encouraging results prove the practical feasibility of the approach.

Identifying Potential Landslides by Stacking-InSAR in Southwestern China and Its Performance Comparison with SBAS-InSAR

Landslide disasters occur frequently in the mountainous areas in southwest China, which pose serious threats to the local residents. Interferometry Synthetic Aperture Radar (InSAR) provides us the ability to identify active slopes as potential landslides in vast mountainous areas, to help prevent and mitigate the disasters. Quickly and accurately identifying potential landslides based on massive SAR data is of great significance. Taking the national highway near Wenchuan County, China, as study area, this paper used a Stacking-InSAR method to quickly and qualitatively identify potential landslides based on a total of 40 Sentinel SAR images acquired from November 2017 to March 2019. As a result, 72 active slopes were successfully detected as potential landslides. By comparing the results from Stacking-InSAR with the results from the traditional SBAS-InSAR (Small Baselines Subset) time series method, it was found that the two methods had a high consistency, with 81.7% potential landslides identified by both of the two methods. A detailed comparison on the detection differences was performed, revealing that Stacking-InSAR, compared to SBAS-InSAR may miss a few active slopes with small spatial scales, small displacement levels and the ones affected by the atmosphere, while it has good performance on poor-coherence regions, with the advantages of low technical requirements and low computation labor. The Stacking-InSAR method would be a fast and powerful method to qualitatively and effectively identify potential landslides in vast mountainous areas, with a comprehensive understanding of its specialty and limitations.

Spatial Variation of Surface Ozone Concentration During the Warm Season and Its Meteorological Driving Factors in China

The concentration of surface ozone (O3) in China increased consistently from 2015 to 2018, and became an important air pollutant, followed by particulate matter. This study uses real-time O3 and meteorological data, obtained in 337 cities in China during the warm seasons (April to September) of 2015 to 2018, to determine the spatial variation of surface O3 and its meteorological driving factors in major cities in China, via trend analysis, spatial autocorrelation, hotspot analysis, and multi-scale geographically weighted regression (MGWR) modeling. The results show that: ① during the warm season, O3 concentrations showed a significant growth trend (P<0.05), with an average growth rate of 0.28 μg·(m3·a)-1, while more than 55% of urban O3 concentrations increased by 0.50 μg·m-3 annually. ② There were significant regional differences in O3 concentration. High values (>60 μg·m-3) were distributed over east China, north China, central China, and northwest China, while low values (<20 μg·m-3) were distributed over south China and southwest China. ③ The spatial agglomeration of O3 concentration has been enhanced year by year, with hotspots mainly distributed over east China and central China. In contrast, there are cold spots in northeast China, southwest China, and southern China. ④Analysis of the MGWR model indicated that temperature, wind speed, cloud coverage, and precipitation all have a significant effect on the distribution of O3, although there are also discrepancies in driving factor priorities between the different regions. Temperature was the main meteorological driving factor of O3 variation during the warm season in China, and its impact on O3 concentration was significantly higher in north China, northwest China, and northeast China than in other regions; overall, there was a significant positive correlation between O3 concentration and temperature, except in Guangxi, Yunnan, and Jiangxi. O3 concentration was negatively correlated with wind speed in most regions of south China, east China, and central China, and positively correlated with wind speed in north China and northeast China. O3 concentration was significantly negatively correlated with cloud cover, except in Liaoning, Shandong, Hebei, Gansu, Guangdong, and some areas in southwest China. O3 concentration was significantly negatively correlated with precipitation, except in the northwest and southwest regions.

Catastrophe Mechanism of Stress-Fissure Coupling Field in Mining Close Distance Seams in Southwest China

For the sake of studying the catastrophe mechanism of stress-fissure coupling field in mining close distance seams in southwest China, a test working face in Guizhou province in southwest China is adopted and researched by the methods of numerical calculation and similar experiment. When the working face advances to 180 m in 4# coal seam in a similar experiment, the overlying rock breaks to the central base plate of Yulongshan limestone, and the conductive fractures run through the Changxing limestone karst cave and Yulongshan limestone karst cave. When the 1402 working face advances to 350 m, the top of vertical karst caves in the middle of the model produces extrusion damage, forming a penetrating water inrush passage. When the 1402 working face advances to 480 m, the top slab of the working face comes under periodic weighting with the short step. Besides, the mining of 9# coal seam starts after 4# coal seam in mining close distance seams. When the working face in 9# coal seam advances to 340 m in numerical simulation, the maximum opening of the overburden fractures is 51.16 mm. The fractures in the roof are mainly caused by the periodic breaking and falling of the basic roof, connected with the floor fractures of 4# coal seam. When the working face in 9# coal seam advances to 500 m, the maximum opening of the overburden fracture is 93.09 mm. Specifically, as the working face advances, the opening of fracture in the roof after collapse of the basic roof periodically is mainly greater than 5 mm, and the compaction closure is mainly 1 mm-5 mm. The fractures in the gob floor are mainly 0.1 mm-1 mm, and the fracture opening of the collapsed rock mass in the gob is mainly 1 mm-5 mm and greater than 5 mm. The karst caves in the overburden reduce the periodic weighting step of working face and play a guiding role in the direction of fracture development and water inflow passage formation. The karst caves are connected to surface waterfall holes and trap pits, and atmospheric precipitation recharges the water in the caves. The research results can be treated as an important basis for the prevention and treatment for water inrush disaster in mining close distance seams in the karst area of southwest China.