Stable Areas Research Articles

TRACES OF SEISMIC ACTIVITY IN THE LAKE BOTTOM SEDIMENTS OF EASTERN FENNOSCANDIA

This paper presents the results of a study on traces of ancient earthquakes in the lake bottom sediments of eastern Fennoscandia (Kola region and Karelia). Based on the sediment cores from six lake basins located within large active structures of the region, consideration is being given to the most typical features of sedimentation affected by neotectonic movements of the Earth’s crust. The data presented here provide lithological-stratigraphical, paleobotanical and chronometrical evidence for lakes. The paper causes and mechanisms of formation of seismic structures in bottom sediments and their distinction from deformations of another origin. Generalized earthquake history in provided an opportunity to organize the existing information on the time of paleoearthquake manifestations and distinguish three active periods in paleoseismicity. These are Late Glaciation-Early Holocene marked by the most rapid uplift after the retreat of the last ice sheet (13500–8100 cal yr BP), Middle Holocene (6800–6600 cal yr BP), and Late Holocene (3100–200 cal yr BP). The results of this study showed that the number and intensity of seismic events changed at different stages of sedimentation. Since the Younger Dryas, fault zones (or their segments) have been repeatedly activated. Combined with the data on paleoseismicity in adjacent parts of Fennoscandia, our studies indicate an irregular pattern of the Late Pleistocene-Holocene seismic activity in stable areas formerly covered by glaciers. The obtained data make further adjustments to the neogeodynamic and seismic estimates of intraplate areas.

Spatio-temporal variations and drought of spring maize in Northeast China between 2002 and 2020.

A lot of spring maize is grown in Northeast China (Liaoning, Jilin, and Heilongjiang), an area that is highly susceptible to drought. Here, remote sensing indexes from 2002 to 2020 were studied using the 8-day surface reflectance and land surface temperature of Moderate-resolution Imaging Spectroradiometer data. Spring maize distribution was extracted using a decision tree classification, and the results were compared to the known distribution based on field investigation data and published statistics. The results showed that mixed pixels of spring maize and soybeans had limited influence on the study of spatio-temporal variations of spring maize, and the error was acceptable. The overall accuracy of verifying the spring maize distribution from 2018 to 2020 was above 85%. The stable, fluctuating, and low-frequency planting areas of spring maize accounted for 11.86%, 17.41%, and 34.86% of the study area, respectively. In 2015, the government directed a reduction of the planting area of spring maize in the "Liandaowan" region of Northeast China. The planting area of spring maize was characterized by a continuous increase before this change (2002-2014), exhibited changes and reductions in response to the change (2015-2017), and exhibited optimization and recovery after this change (2018-2020). Compared with the fluctuating and low-frequency planting areas, moderate and severe droughts were higher in stable planting areas. From 2002 to 2020, the most severe droughts occurred in the expanded planting areas. This rapid and large-scale monitoring of spatio-temporal variations and drought of spring maize provides a foundation for improving grain yield. This method could be easily applied to the study of other regions and combined with high-resolution and hyperspectral satellite data to improve monitoring accuracy.

Stability and dynamic response of two-stage hydropower stations cascaded by regulating reservoir

This paper studies the stability and dynamic response of two-stage hydropower stations cascaded by regulating reservoir. Firstly, the model of the two-stage hydropower stations cascaded by regulating reservoir is established. Then, the stability and dynamic response of two-stage hydropower stations are analyzed. Finally, the effects of sectional area of regulating reservoir on the stability and dynamic response based on the first-stage and second-stage hydropower stations are analyzed. The critical stable sectional area of regulating reservoir is determined. The results show that, the stable domain of the first-stage hydropower station is smaller than that of the second-stage hydropower station because of the feedback mode of water level of regulating reservoir and parameters of two-stage hydropower stations. The sectional area of regulating reservoir has a remarkable influence on stable domains and dynamic response processes. Under different combinations of proportional gain and integral gain of governor, the critical stable sectional area of regulating reservoir has two positive solutions. The intersection, curves of the critical stable sectional area of regulating reservoir and integral gain of governor, divides the parameter plane into stable domain and unstable domain. The stability of two-stage hydropower stations becomes better with the decrease of integral gain of governor.

An Investigation of Cloudburst-triggered Landslides and Flash Floods in Arakot Region of Uttarkashi District, Uttarakhand

Abstract A cloudburst event occurred at around 04:00hrs (IST), on 18, August 2019, elicited landslides and flash floods, at Tikochi and Makudi village under the Arakot region of Uttarkashi District, Uttarakhand, India. This heavy rain has caused a massive flash flood in Arakot Nala and induced a major landslide downstream. This flash flood has caused the death of 19 people, 8 were missings, and 15 were injured, affecting 38 villages (70 km2 area) and stranding more than 400 people at various places. These flash floods have caused irreparable damage to the livestock, infrastructures, environment, and properties in the Uttarakhand and Himachal states and estimated economic losses of about Rs ~175 crores. During the same period, heavy rainfall also made havoc across north India. Meanwhile, the rescue and evacuation process in the region has been carried out by the Indo-Tibetan Border Police (ITBP), National Disaster Response Force (NDRF), and State Disaster Response Force (SDRF). However, it will take a lot of time to bring the situation in the region to normalcy. The study has suggested that pragmatic check dam policy and logical shifting of the people should be exercised in a safe and stable area before the onset of the monsoon season in the hazard-prone areas. An early warning system (EWS), installation of Doppler radar, and lightning sensors, which would be helpful for policymakers, planners, practitioners, and technologists will aid to minimize the disaster risk and sustainable development within the region. Although an EWS alone can not stop a similar type of disaster but would be very helpful in minimizing the loss of human lives, livestock, biodiversity, infrastructure (civilian and strategic), and land holding in the hilly region.

Exploring the Relationship between Ecosystem Services under Different Socio-Economic Driving Degrees.

The large-scale transformation of natural ecosystems to socio-economic development land types under human activities was a primary reason for the decline of regional ecosystem services. It is a key issue for regional ecosystem planning and management to reveal the relationship between ecosystem services of different land use types under different socio-economic driving degrees. However, the current related research was not in-depth. Based on the land use data of Wuhan City in 1980, 1990, 2000, 2010, and 2020, this study classified land use into three categories according to the different degrees of human activities on natural ecosystem development: the land use of a natural ecosystem (LUNE), the land use of a productive ecosystem (LUPE), and the land use of a socio-economic system (LUSE). The InVEST model was used to simulate five ecosystem services (grain yield, water yield, carbon storage, habitat quality, and water purification), and the spatio-temporal distribution and functional transformation of the three land use types were analyzed. Results showed that with the intensified urban expansion in Wuhan, the LUSE types increased to 2.7 times that of the original. However, the natural land types basically maintained a stable area, coupling with the large-scale transformation between the LUPE and LUSE types. Land use change resulted in significant spatial changes of five ecosystem services, especially carbon storage and habitat quality. The correlation analysis indicated that the five kinds of ecosystem services mainly showed a synergistic relationship, meanwhile the LUSE type denoted the most significant correlation with ecosystem services among these three category types. This study indicated that besides the protection of natural ecosystems, the LUSE type would become the key land use type in the planning and management of improving regional ecological function.

Regional‐Scale Landscape Response to an Extreme Precipitation Event From Repeat Lidar and Object‐Based Image Analysis

AbstractExtreme precipitation events may cause flooding, slope failure, erosion, deposition, and damage to infrastructure over a regional scale, but the impacts of these events are often difficult to fully characterize. Regional‐scale landscape change occurred during an extreme rain event in June 2012 in northeastern Minnesota. Landscape change was documented by 8,000 km2 of airborne lidar data collected before and after the event. Following improved alignment of the lidar point data and reducing error using insight from analysis of extensive stable areas, elevation differences were classified into map objects representing geomorphic change in relation to process and landscape position using object‐based image analysis. This remote mapping compares favorably to field and imagery‐based mapping and provides the basis for volumetric sediment budgeting. Elevation differences in these objects indicate that 4.5 × 106 ± 1.0 × 106 m3 of sediment was eroded in the study area. Of this, 2.5 × 106 ± 3.3 × 105 m3 was deposited in deposits on hillslopes and valley floors, and 2.0 × 106 ± 4.6 × 105 m3 were removed from watersheds and exported to the Saint Louis River Estuary and Lake Superior. Multivariate logistic regression analysis emphasized that topographic slope and presence of glaciolacustrine clay lithology are the primary control on landslide occurrence, and landslides occur most frequently on slopes within tens of meters of stream channels. These results provide the basis to anticipate the impacts of similar future storm events. Because precipitation events are forecast to continue to increase in frequency and intensity owing to climate change, characterizing and anticipating their effects may support hazard planning.

Proposal of novel chatter-free milling strategy utilizing extraordinarily numerous flute endmill and high-speed high-power machine tool

This paper proposes a novel chatter-free milling strategy that utilizes the infinite stable area, i.e., area below the high-speed part of the 0-th lobe, which has not been generally utilized to date. In the conventional methodology, the stable pockets are utilized to realize a high axial depth of cut. However, these pockets tend to shift, e.g., due to long-term deterioration of the spindle, and hence they sometimes cannot be utilized effectively. The proposed strategy combines an extraordinarily numerous flute endmill, e.g., 20 flutes, and a high-performance spindle, e.g., capable of a spindle speed of 33000 min−1, installed on a high-speed high-power machine tool. By increasing the number of flutes, the stability lobes shrink in inverse proportion to that number against the spindle speed and the depth of cut, and the infinite stable area can be utilized in the practical spindle speed zone of recent machine tools. A design method is proposed for the cutting tool and the cutting conditions to utilize this area effectively. Analyses and experiments are conducted to verify the effectiveness of the proposed milling strategy. In the experiments, the material removal rate reaches 2904 cc/min at the spindle speed of 33000 min−1 and the axial depth of cut of 110 mm with no chatter vibration. The infinite stable area is capable of much higher stability and machining ability than the conventionally utilized stable pockets.

Supervoxel-based targetless registration and identification of stable areas for deformed point clouds

Abstract Accurate and robust 3D point cloud registration is the crucial part of the processing chain in terrestrial laser scanning (TLS)-based deformation monitoring that has been widely investigated in the last two decades. For the scenarios without signalized targets, however, automatic and robust point cloud registration becomes more challenging, especially when significant deformations and changes exist between the sequence of scans which may cause erroneous registrations. In this contribution, a fully automatic registration algorithm for point clouds with partially unstable areas is proposed, which does not require artificial targets or extracted feature points. In this method, coarsely registered point clouds are firstly over-segmented and represented by supervoxels based on the local consistency assumption of deformed objects. A confidence interval based on an approximate assumption of the stochastic model is considered to determine the local minimum detectable deformation for the identification of stable areas. The significantly deformed supervoxels between two scans can be detected progressively by an efficient iterative process, solely retaining the stable areas to be utilized for the fine registration. The proposed registration method is demonstrated on two datasets (both with two-epoch scans): An indoor scene simulated with different kinds of changes, including rigid body movement and shape deformation, and the Nesslrinna landslide close to Obergurgl, Austria. The experimental results show that the proposed algorithm exhibits a higher registration accuracy and thus a better detection of deformations in TLS point clouds compared with the existing voxel-based method and the variants of the iterative closest point (ICP) algorithm.

Spatiotemporal Evolution and Driving Forces of Vegetation Cover in the Urumqi River Basin.

It is important to determine long-term changes in vegetation cover, and the associated driving forces, to better understand the natural and human-induced factors affecting vegetation growth. We calculated the fractional vegetation coverage (FVC) of the Urumqi River basin and selected seven natural factors (the clay and sand contents of surface soils, elevation, aspect, slope, precipitation and temperature) and one human factor (land use type). We then used the Sen-Man-Kendall method to calculate the changing trend of the FVC from 2000 to 2020. We used the optimal parameters-based geographical detector (OPGD) model to quantitatively analyze the influence of each factor on the change in vegetation coverage in the basin. The FVC of the Urumqi River basin fluctuated from 2000 to 2020, with average values between 0.22 and 0.33. The areas with no and low vegetation coverage accounted for two-thirds of the total area, whereas the areas with a medium, medium-high and high FVC accounted for one-third of the total area. The upper reaches of the river basin are glacial and forest areas with no vegetation coverage and a high FVC. The middle reaches are concentrated in areas of urban construction with a medium FVC. The lower reaches are in unstable farmland with a medium and high FVC and deserts with a low FVC and no vegetation. From the perspective of the change trend, the areas with an improved FVC accounted for 62.54% of the basin, stable areas accounted for 5.66% and degraded areas accounted for 31.8%. The FVC showed an increasing trend in the study area. The improvement was mainly in the areas of urban construction and desert. Degradation occurred in the high-elevation areas, whereas the transitional zone was unchanged. The analysis of driving forces showed that the human factor explained more of the changes in the FVC than the natural factors in the order: land use type (0.244) > temperature (0.216) > elevation (0.205) > soil clay content (0.172) > precipitation (0.163) > soil sand content (0.138) > slope (0.059) > aspect (0.014). Apart from aspect, the explanatory power (Q value) of the interaction of each factor was higher than that of the single factor. Risk detection showed that each factor had an interval in which the change in the FVC was inhibited or promoted. The optimum elevation interval of the study area was 1300-2700 m and the greatest inhibition of the FVC was seen above 3540 m. Too much or too little precipitation inhibited vegetation coverage.

Thermo-mechanical coupled flow behavior evolution of Zr-based bulk metallic glass

Machining is an essential process for manufacturing high-precision bulk metallic glass (BMG) components, but the flow behavior of thermodynamically metastable BMGs during machining with high temperature and high strain rate conditions is still unclear. In this study, the flow behavior of Zr-based BMG is investigated in an orthogonal cutting operation. The results show that the increase of the temperature at the initial stage of cutting enables the amorphous chips gradually change from a laminated structure to a viscous flow state, and attach to the cutting edge of the tool. The chip in the stable sticking area of the tool-chip interface is a composite material rich in various crystalline phases and quasi-crystals with obvious phase separation, while the chips far away from the interface still maintain the amorphous state with uniform composition. After the formation of stable adhesion, the cutting force and cutting temperature are relatively stable, and the viscous-fluid chips act as a protective layer for the tool, avoiding severe tool wear.

Rift-uplift-depression accumulation-controlling models of the large gas province in Cambrian pre-salt, Tarim Basin, China

The Cambrian pre-salt has the accumulation conditions for forming a compound large gas province and was the strategic replacement area with the lowest exploration level and the largest exploration potential in the Tarim Basin. However, no significant discoveries have been found in the exploration for many years. The key problem is that the unclear controlling factors and spatial distribution of the hydrocarbon generation center and scale beach reservoir result in the ambiguity of favorable exploration directions and zones. Given this, a comprehensive application of seismic, drilling, well-logging, mud-logging, and geochemical data has been carried out to study the source-controlling, reservoir-controlling, caprock-controlling, and accumulation-controlling of the Cambrian pre-salt area, constructing the accumulation-controlling model and defining the favorable zones and exploration breakthrough direction. The following points have been gained: (1) Paleo-rifts controlled hydrocarbon generation center. The rift-depression structure formed in the Nanhua System to Sinian System provided the structural background for the development of the Lower Cambrian and controlled the deposition of the Cambrian Yuertusi Formation. In the negative tectonic area controlled by rifting, the thickness of the Yuertusi Formation was large and formed the hydrocarbon generation center. (2) The paleo-uplifts controlled the development of beach facies dolomite reservoir. The paleo-uplifts formed simultaneously with the Nanhua System paleo-rifts controlled the development and distribution of high-energy beaches in the Xiaerbulake Formation, and large-scale dolomitic beach facies reservoirs were formed on both sides of the Tanan paleo-uplift. (3) The paleo-depression controlled the development of gypsum-salt caprock. In the Middle and Late Cambrian, the Taxi platform has closed and formed a strong evaporation environment, while a wide-covering gypsum-salt caprock was deposited in the unified depression within the platform due to the development of the Luntai-Gucheng near the north-south rimmed platform margin. (4) The time-space matching of rift-uplift-depression controlled the formation and distribution of oil and gas. Three types of accumulation-controlling models, the stable rift-uplift-depression, the active rift-uplift-depression, and the transitional rift-uplift-depression, were established, indicating the stable and transitional areas as the main exploration directions, and the Aman low uplift between Awati Sag and Manxi Sag as the preferred target area for the large gas province in Cambrian pre-salt.

Direct-Use Geothermal Energy Location Multi-Criteria Planning for On-Site Energy Security in Emergencies: A Case Study of Malaysia

Geothermal potential is a significant advantage in terms of renewable energy for countries located on the Pacific Ring of Fire. Studies on geothermal energy sources show that Malaysia is one of the countries possessing this inexhaustible and stable energy source. This on-site energy source is a promising solution to the problem of energy security during emergencies where the energy supply chain is disrupted. To exploit this advantage, this study proposes a novel tri-layer framework to prioritize locations for direct-use geothermal energy location (DGL) in Malaysia. First, the proposed locations are screened for feasibility to limit the impact on other natural conservation areas and stable residential areas. In the second layer, locations are evaluated for efficiency using the data envelopment analysis (DEA) model based on quantitative indicators. In the third layer, the spherical fuzzy extended combination of the analytic hierarchy process (SF AHP) and the combined compromise solution (SF CoCoSo) methods are introduced and applied to prioritize high-efficiency locations. According to the findings, costs, social acceptance, and noise impacts are the qualitative criteria of most concern for DGLs. Through the tri-layer framework, the suggested concordant locations for DGLs in Malaysia are Marudi of Sarawak, Tawau of Sabah, Serian of Sarawak, and Jeram of Selangor.

Distance-restrained atmospheric parameters correction (DR-APC) model for GB-SAR transmission power attenuation compensation in bridges dynamic deflection measurement

A distance-restrained atmospheric parameter correction (DR-APC) model is presented in this study to reduce the influences of atmospheric parameters and electromagnetic wave power attenuation on dynamic deflection measurement of bridges using ground-based synthetic aperture radar (GB-SAR). The proposed model considers electromagnetic wave transmission distance together with factors of bridges geometric configuration, instrument layout and atmospheric refractive index. First, the theoretical DR-APC model is derived with restrictions of the wave propagation distance, the height from radar unit to bridge lower surface and the elevation angle of radar unit. Second, the DR-APC model is determined based on continuous time-series displacement of 12 corner reflectors fixed on tripods in a stable environment area. Finally, the DR-APC model is applied to GB-SAR monitoring signals of three bridges to verify its effectiveness. The results show that the proposed model has an ability to improve the accuracy of dynamic deflection measurement using GB-SAR.

Optimal pitch angles determination of ball-end cutter for improving five-axis milling stability

Regenerative chatter is one of the major limitations in five-axis ball-end milling of complex shaped parts, resulting in reduced productivity and poor quality. Although a good solution can be provided for the chatter avoidance and the stability enhancement by using variable pitch cutters, it depends on the optimal selection of pitch angles, and few studies focus on determining the optimal pitch angles combination for the five-axis ball-end milling process in a continuous spindle speed range. In this paper, the pitch angle optimization is based on the fast and accurate stability prediction of five-axis ball-end milling with variable pitch tools. Considering that the search space of the stability border should be reduced as much as possible during the optimization process, an approach combining an improved hybrid multi-step method and an optimization strategy of stable area maximum is presented for efficiently finding the optimal pitch angles. For selected spindle speed ranges and given lead/tilt angles, the optimal pitch angles of variable pitch ball-end cutter are determined with the proposed optimization approach. The experimental results show the average stability of the customized optimal variable pitch ball-end cutter is significantly higher than that of the regular ball-end cutter, validating the proposed optimal pitch angles determination method. Compared with the semi-discretization method, the use of improved hybrid multi-step method for predicting the stability border reduces the simulation time by around 84 %. In contrast to the optimization strategy based on the average characteristic multiplier, the proposed optimization strategy is more efficient because it does not require a large number of characteristic multipliers.

Unsustainable Anthropogenic Activities: A Paired Watershed Approach of Lake Urmia (Iran) and Lake Van (Turkey)

Water availability in lakes must be studied in order to better manage ecosystems within lake basins and meet economic development needs. Despite being Iran’s largest lake, Lake Urmia’s water level and surface area have declined dramatically over the past two decades. During the same period, Lake Van in Turkey maintained a relatively stable water level and surface area. As a result, comparing factors related to water level and surface area in these lakes, which have similar geographical and climate conditions but different management policies, can be an appropriate way to identify the causes of water declines in Lake Urmia. Comparing these variables may help explain observed differences in lake behavior between 2000 and 2016. Hydrometric and climatic parameters, as well as the Normalized Difference Vegetation Index (NDVI) and the Normalized Difference Water Index (NDWI), were used to achieve this goal. Changes in precipitation, temperature, and evapotranspiration in both lakes show essentially identical trends, but this is not a convincing explanation for Lake Urmia’s water surface changes. The results revealed that dam construction and water diversion projects, the expansion of irrigated agriculture, and the lake’s shallow depth in most parts were the primary causes of Lake Urmia’s shrinkage compared to Lake Van.

Multimorbidity in Large Canadian Urban Centres

Abstract Introduction Although health outcomes are related to the characteristics of the geographic areas in which people live, there is limited knowledge on how the prevalence of multimorbidity varies within and across major Canadian urban centres. Our goal was to assess the level of between-neighbourhood variation in the prevalence of multimorbidity in Canada's large urban centres, controlling for compositional effects associated with demographic and socioeconomic factors. Methods Cross-sectional data from the 2015-2018 cycles of the Canadian Community Health Survey (CCHS) were used. Respondents (20 years and older) residing in one of the 35 census metropolitan areas (CMAs) were included (N = 100,803). Census tracts (CTs), relatively small and stable geographic areas nested within CMAs, were used as a measure of neighbourhood. To assess the between-neighbourhood differences in multimorbidity prevalence, we fitted sequential random intercept logistic regression models. Results During the 2015-2018 period, 8.1% of residents of large urban centres in Canada had multimorbidity. The results from the unadjusted model indicate that 13.4% of the total variance in multimorbidity could be attributed to the between-neighbourhood differences. After adjustment for overall characteristics of the CMAs in which these neighbourhoods are located, as well as for individual-level demographic and socioeconomic factors related to compositional effects, 11.0% of the individual variance in multimorbidity could still be attributed to the between-neighbourhood differences. Discussion and Conclusions There is significant and substantial geographic variation in multimorbidity prevalence across neighbourhoods in Canada's large urban centres. Residing in some neighbourhoods could be associated with increased odds of having multimorbidity, even after accounting for overall characteristics of the CMAs in which these neighbourhoods are located, as well as individual-level factors.

Analysis of Dynamic Evolution and Spatial-Temporal Heterogeneity of Carbon Emissions at County Level along "The Belt and Road"-A Case Study of Northwest China.

Northwest region is the main energy supply and consumption area in China. Scientifically estimating carbon emissions (CE) at the county level and analyzing the spatial-temporal characteristics and influencing factors of CE in a long time series are of great significance for formulating targeted CE reduction plans. In this paper, Landscan data are used to assist NPP-VIIRS-like data to simulate the CE from 2001 to 2019. Spatial-temporal heterogeneity of CE was analyzed by using a two-stage nested Theil index and geographically and temporally weighted regression model (GTWR). The CE in northwest China at the county increases yearly while the growth rate slows down from 2001 to 2019. The spatial pattern forms a circle expansion centered on the high-value areas represented by the provincial capital, which is also obvious at the border between Shaanxi and Ningxia. Axial expansion along the Hexi Corridor is conspicuous. The spatial pattern of CE conforms to the Pareto principle; the spatial correlation of CE in northwest counties is increasing year by year, and the high-high agglomeration areas are expanding continuously. It is an obvious high carbon spillover effect. Restricted by the ecological environment, the southwest of Qinghai and the Qinling-Daba Mountain area are stable low-low agglomeration areas. The spatial pattern of CE in northwest China shows remarkable spatial heterogeneity. The difference within regions is greater than that between regions. The “convergence within groups and divergence between groups” changing trend is obvious. According to the five-year socioeconomic indicators, the economic scale (GDP), population scale (POP), and urbanization level (UR) are the main influencing factors. The direction and intensity of the effect have changed in time and space. The same factor shows different action intensities in different regions.

Construction and Application of Mathematical Model of Stable Fracture Development Zone of Roof

The fractured zone in the overlying strata of a coal mine goaf is vital for effective gas drainage. The development height of the fractured zone is lied on the “saddle type” theory and calculated by empirical formula, while the horizontal range is dependent on the caving theory of the “O” circle. However, the height of the fracture zone obtained using the above method is usually too large, and only the horizontal boundary of the fracture zone is defined. Besides, the fracture development degree in different regions is not described. To accurately determine the stable development area of the fractured zone and locate the gas migration channel as well as gas enrichment horizon, in this paper, a geometric and mathematical model for gas extraction in the fractured zone is established based on common high-level drilling. Then, a method of investigating the parameters of the directional high-level drilling in the roof is proposed, and a solving means is provided. Taking Wanfeng Coal Mine as an engineering background, the reasonable parameters of the common high-level drilling were investigated, and the effect was verified using the directional high-level drilling in the roof of an adjacent working face. The results show that the stable extraction volumes of the two directional drilling holes is 1~1.8 m3/min and 0.6~1 m3/min, respectively, which exceeds the optimal extraction volumes of the ordinary drilling holes. The new method of determining the stable development area of the fractured zone is significant for improving the gas drainage effect of the high-level drill holes in the roof.

Hot deformation behavior, microstructure evolution and slip system of Mg-2Zn-0.5Mn-0.2Ca alloy

The hot deformation behavior of as-cast Mg-2Zn-0.5Mn-0.2Ca alloys was investigated by hot compression tests conducted at 250–400 °C with strain rates of 0.001–1 s−1. The true stress–strain curves showed that flow stress increased with the increase of strain rates and decrease of temperatures. The constitutive equation was obtained, and the calculated average activation energy is 196.79 kJ mol−1. The processing map is developed. Combined with the analyses of microstructural and processing map, the optimal processing parameter is determined at 350 °C and 0.001–0.1 s−1. Based on EBSD analysis, the microstructures of the instability areas and the stable areas are quite different, yet both have a <0001>//CD texture. The slip system in deformed grains was determined by the in-grain misorientation axis (IGMA) analysis. Typical discontinuous dynamic recrystallization (DDRX) mechanism is the main dynamic recrystallization (DRX) mechanism. As the decrease of the strain rates and the increase of the deformation temperatures, the DRX fraction gradually increased, meanwhile, the behavior of DRX has an obvious weakening effect on texture strength.

Realizing certainty in an uncertain future climate: modeling suitable areas for conserving wild Citrus species under different change scenarios in India.

Citrus is an important horticultural crop of India and is often prone to diseases, particularly under increased temperature scenarios. For developing disease-resistant Citrus varieties, conservation of wild relatives is extremely important. However, our knowledge on temperature tolerance of these wild relatives of Citrus to varied climate change scenarios is extremely limited. Therefore, we determined the climatic niche of six wild relatives of cultivated Citrus species (C. indica Tanaka, C. karna Rafin., C. latipes (Swingle) Tanaka, C. macroptera Montrouz., C. medica L., and C. sinensis (L.) Osbeck.) and identified the geographical areas in India that would remain climatically stable in future through ecological niche modeling (ENM). Raster data on 19 bioclimatic variables with a resolution of 0.04° were used to generate niche models for each Citrus species that delineated their potential distribution areas. Future species distribution predictions for the year 2050 were made using the climate change scenarios from the most appropriate climate models, i.e., IPSL-CM5A-LR and NIMR-HADGEM2-AO with four Representative Concentration Pathways (RCPs). Ensemble of current and future projections was used to identify climatically stable areas for each species. Precipitation-related bioclimatic variables were the key climatic determinants for the modeled distribution pattern. The consensus of current and future projections suggests that most areas with stable climates for the species in the future would be available in the northeastern states of Arunachal Pradesh, Meghalaya, Mizoram, and Tripura. Efforts for in situ conservation and establishment of germplasm banks and citrus orchards may be encouraged in these identified areas.