Average Expansion Research Articles

Urban growth in peri-urban, rural and urban areas: Mexico City

This remote sensing study compares growth occurring in three urban types between 2005 and 2014: peri-urban, rural and urban, in a fast-growing metropolitan region west of Mexico City. Future urban growth for the period 2014–24 is modelled using the land-use/cover change (LUCC) model Geomod. Urban expansion is correlated with some socio-territorial factors and the impacts are assessed for the loss of biomass. In both periods, the urban zone differed the most from the other two in terms of urban expansion. The Geomod predictions overestimate the urban expansion in the urban zone and underestimate it in the peri-urban and rural zones. Significant differences exist in the average urban expansion between zones. The main urban growth drivers were elevation, population density, distance to previous urban land and distance to roads. A substantial loss of biomass is due to urban growth, including expansion and infill. The research reveals significant differences in growth between peri-urban, rural and urban areas, and contributes spatial information for designing focused land-use policies in dynamic urban contexts. <em><strong>Policy relevance</strong></em> This article contributes to understanding the differentiated urban growth of urban, peri-urban and rural areas, which can translate into more precise and effective public policies. Urban expansion and infill patterns differ. For peri-urban and rural areas, the main growth is infill, so actions should be implemented to sustainably manage the vacant or undeveloped land within an existing human settlement to prevent further expansion, but also to avoid the loss of priority areas for the provision of ecosystem services. In urban areas where the main urban increment is expansion, sensible consolidation decisions need to be taken to avoid further urban expansion and the incorporation of urban green space.

Average sampling expansions from regular and irregular samples over shift-invariant subspaces on LCA groups

Average sampling expansions from regular and irregular samples over shift-invariant subspaces on LCA groups

Determinants Of The Instability Of The Russian Economic Growth

Based on a detailed comparative analysis of the concepts of &amp;quot;economic growth&amp;quot; and &amp;quot;economic development&amp;quot;, the article provides arguments in favor of the thesis that from the post-default period to the present day, the Russian economy demonstrates not only steadily fading average annual GDP expansion rates, but also the so-called &amp;quot;impoverishing growth&amp;quot;, &amp;quot;growth without development&amp;quot;. The leading characteristic of the low-quality growth is recognized as the long-term evolution of the domestic economy in the vein of the historically futile natural resource export model, which, through the mechanisms of the &amp;quot;Dutch disease&amp;quot; and regular fluctuations in global energy prices, moves in an excessively cyclical form, inevitably making the socio-economic development of the country unstable. Significant determinants of its unstable growth, carefully concealed by the methods of misleading macroeconomic statistics presented in the article, are also uncovered being the dominance of extensive factors over the intensive ones associated with increasing macroeconomic efficiency and achieving accumulation rates close to the optimum values, the socially conflicting nature of GDP growth, accompanied by the excessive income inequality, both in terms of income and property, even in the relatively favorable conditions compared to global practice, and the resource-intensive and wasteful nature of the dynamics of the national economy.

Deep Well and Ultra-Deep Well Drilling and Completion Technology Optimization and Application of Kuche Piedmont Area

In recent years, the exploration and development of China's Tarim Basin has moved towards ultra-deep and complex areas. With the increase in well depth and the influence of the geological characteristics of the Kuche Piedmont area, a series of drilling problems for 8000m-level ultra-deep wells in this area have been caused. As a result, a series of new drilling and completion technologies have been formed: ①Based on the tower standard I type well structure, the improved tower standard II-B\II-C type well structure is used to solve the drilling of two sets of salt formations. Difficulties; ②Optimizing UDM-2 oil-based drilling fluid, achieving an average hole diameter expansion rate of only 6.82%, reducing lost circulation and other complications; ③Designing and optimizing a new type of multi-edge PDC bit to significantly increase the average ROP; ④Application The industry-leading pre-measurement resistivity technology successfully predicts the salt bottom; ⑤The application of fine controlled pressure cementing technology to achieve effective sealing of high-pressure saline formations. In recent years, the Kuche Piedmont Block in the Tarim Basin has continued to tackle key problems in the application of ultra-deep well drilling and completion technologies, and has successfully reached a new level of 8000m, which has played an important role in supporting the development of deep oil and gas exploration and development business.

Axial-offset analysis in iPWR by developing the neutronic/thermal-hydraulic core simulator based on coarse-mesh methods

Axial-Offset (AO), as an important operational parameter, should be monitored in the load-following procedure due to the safety limits related to xenon oscillation and axial peaking factor in a nuclear power plant. In this study, to calculate AO for a Small Modular Reactor, a neutronic/thermal–hydraulic simulator has been developed based on coarse mesh methods. In this simulator, the average current nodal expansion method and the single heated channel approach have been used for neutronic and thermal–hydraulic analysis, respectively. The developed simulator is verified by the IAEA-3D model and thermal–hydraulic benchmark model. As the iPWR small modular reactor case study, SMART reactor has been simulated, and the neutronic and thermal–hydraulic parameters have been calculated. For investigation of AO behavior during power changes, the regulating bank repositioning approach is employed, and the reactor core characteristics are estimated by a developed simulator. The results demonstrate that the AO variation remains in a safe and standard operating region for SMART reactor.

A simple method for preparing ThO2 ceramics with high density

AbstractA simple and effective method for preparing ThO2 ceramics with high density has been proposed. It mainly includes a positive precipitation approach and a conventional sintering process. The SEM images and laser particle size analysis show that the prepared powder exhibits a round‐plated shape with a uniform and narrow particle size distribution, which is the key to the densification sintering of ThO2 ceramics. The XRD analyses confirm that the ThO2 ceramics sintered at 1590°C were composed of cubic fluorite phase. The effect of sintering temperature on the density of ThO2 ceramics was also investigated, and a relative density higher than 95% were achieved after sintering at 1590°C for 6 h in an air atmosphere. Moreover, the Vickers hardness was up to 8.49 GPa, the average linear expansion coefficient within 40–800°C was low to 10.97 × 10−6/K, and the thermal conductivity and the thermal diffusivity were both higher than most of traditional ceramic materials (16.94–5.86 W/m K and 7.28–1.28 mm2/s, respectively, within the temperature range of 25–800°C). The previous great performances are closely related to its high density, which enables it to be a great candidate for nuclear fuels and other potential application fields.

An X-Ray Proper-motion Study of the Large Magellanic Cloud Supernova Remnant 0509-67.5

We present a third epoch of Chandra observations of the Type Ia Large Magellanic Cloud Supernova remnant 0509-67.5. With these new observations from 2020, the baseline for proper-motion measurements of the expansion has grown to 20 yr (from the earliest Chandra observations in 2000). We report here the results of these new expansion measurements. The lack of nearby bright point sources renders absolute image alignment difficult. However, we are able to measure the average expansion of the diameter of the remnant along several projection directions. We find that the remnant is expanding with an average velocity of 6120 (4900–7360) km s−1. This high shock velocity is consistent with previous works, and also consistent with the inference that 0509-67.5 is expanding into a very low density surrounding medium. At the distance of the LMC, this velocity corresponds to an undecelerated age of 600 yr, with the real age somewhat smaller.

Tissue Expanders in Staged Calvarial Reconstruction: A Systematic Review

Cranioplasties are common procedures in plastic surgery. The use of tissue expansion (TE) in staged cranioplasties is less common. We present two cases of cranioplasties with TE and systematically review literature describing the use of TE in staged cranioplasties and postoperative outcomes. A systematic review was performed by querying multiple databases. Eligible articles include published case series, retrospective reviews, and systematic reviews that described use of TE for staged bony cranioplasty. Data regarding study size, patient demographics, preoperative characteristics, staged procedure characteristics, and postoperative outcomes were collected. Of 755 identified publications, 26 met inclusion criteria. 85 patients underwent a staged cranioplasty with TE. Average defect size was 122 cm 2 , and 30.9% of patients received a previous reconstruction. Average expansion period was 14.2 weeks. The most common soft tissue closures were performed with skin expansion only (75.3%), free/pedicled flap (20.1%), and skin graft (4.7%). The mean postoperative follow-up time was 23.9 months. Overall infection and local complication rates were 3.53 and 9.41%, respectively. The most common complications were cerebrospinal fluid leak (7.1%), hematoma (7.1%), implant exposure (3.5%), and infection (3.5%). Factors associated with higher complication rates include the following: use of alloplastic calvarial implants and defects of congenital etiology ( p = 0.023 and 0.035, respectively). This is the first comprehensive review to describe current practices and outcomes in staged cranioplasty with TE. Adequate soft tissue coverage contributes to successful cranioplasties and TE can play a safe and effective role in selected cases.

Spatio-Temporal Evolution Features and Impact Factors of Urban Expansion in Underdeveloped Cities: A Case Study of Nanchang, China

Studying the expansion of urban construction land is necessary to promote rational land use and scientific territorial spatial planning. To reveal urban built-up areas, this study uses 1990–2020 Landsat remote sensing images, superimposed with NPP/VIIRS nighttime light. To extract urban construction land, support vector machines are then used to conduct classification experiments. The spatial-temporal features are analyzed using the expansion index, the shift of the center of gravity, and expansion direction, while influencing factors are analyzed using a Geodetector. The results show the following: (1) Urban construction land in Nanchang continued expanding from 1990 to 2020, by 385.22 km2, with an average annual expansion intensity of 0.18% and an average annual growth rate of 6.2%. (2) During this time period, the expansion of urban construction land in Nanchang underwent three development stages from: low-strength with low-speed, low-strength with medium-speed, and medium-strength with low-speed expansion. The types of urban construction land expansion were primarily found to be edge expansion and outlying expansion. (3) The overall center of gravity of urban construction land shifts northwest, with significant expansion SW, NW, S, N, and W. (4) Urban planning policy is the dominant driving factor for urban expansion, whereas natural geographic factors have the weakest influence. The results suggest that planning policies should focus on strengthening the rational use and protection of land resources, and promoting the integration and coordinated development of urban functional spaces.

Evaluating the Regional Benefit/Cost Ratio for Transit State of Good Repair Investments

Should transit operators focus scarce funding on maintaining current systems in a state of good repair (SGR), or on expanding transit systems? Prior to this analysis, user impacts of transit SGR had not been systematically calculated. This study develops a new methodology for assessing the impacts of SGR on ridership, vehicle miles traveled, travel times and costs, and public health and safety. This is done for the 25 major transit systems in the nine-county San Francisco Bay Area. Moreover, the study uses a methodology parallel to that used to assess transit system expansion in the Bay Area and, therefore, is able to compare the benefit/cost ratios of transit expansion vs. transit SGR on an even footing. Results indicate regional benefit/cost ratios of close to 3 for transit SGR, with diminishing returns at higher funding levels. This is similar to the benefit/cost ratio of the average transit expansion project.

Hybrid mandibular Bologna midline distractor in combination with surgically assisted rapid maxillary expansion for transverse facial expansion: clinical and cephalometric results

Transverse maxillomandibular hypoplasia can be treated with surgically assisted rapid maxillary expansion (SARME) in association with mandibular symphyseal distraction (MSD). This paper introduces a hybrid mandibular Bologna midline distractor (BMD); the effectiveness of the distractor in combination with SARME for the treatment of transverse skeletal deficiency was evaluated. This two-centre study included 10 patients with a transverse arch width deficit>7 mm and dental crowding, in both the maxilla and mandible, treated with SARME and MSD. The study design was partly retrospective (seven patients) and partly prospective (three patients). Frontal and lateral cephalometric analyses, as well as measurements on dental models, were performed at three different times: before treatment, after the distraction, and 6 months after postoperative orthodontic treatment. The cephalometric analyses and measurements on dental impressions confirmed a balanced and stable skeletal and dental mandibular expansion. An average symphyseal expansion of 7.8 mm was obtained, resolving dental crowding without dental extractions. In conclusion, mandibular expansion performed with the BMD in combination with SARME appears to be a viable surgical approach to transverse maxillomandibular hypoplasia. This technique allows the surgeon to obtain a balanced skeletal and dental expansion, with a low level of relapse.

Real-space determination of the isolated magnetic skyrmion deformation under electric current flow

The manipulation and control of electron spins, the fundamental building blocks of magnetic domains and spin textures, are at the core of spintronics. Of particular interest is the effect of the electric current on topological magnetic skyrmions, such as the current-induced deformation of isolated skyrmions. The deformation has consequences ranging from perturbed dynamics to modified packing configurations. In this study, we measured the current-driven real-space deformation of isolated, pinned skyrmions within Co10Zn10 at room temperature. We observed that the skyrmions are surprisingly soft, readily deforming during electric current application into an elliptical shape with a well-defined deformation axis (semimajor axis). We found that this axis rotates unidirectionally toward the current direction irrespective of electric current polarity and that the elliptical deformation reverses back upon current termination. We quantified the average distortion δ, which increased by ∼90% during the largest applied current density |j| = 8.46 ×109 A/m2 when compared with the skyrmion's intrinsic shape ([Formula: see text]). Additionally, we demonstrated an approximately 120% average skyrmion core size expansion during current application, highlighting the skyrmions' inherent topological protection. This evaluation of in situ electric current-induced skyrmion deformation paints a clearer picture of spin-polarized electron-skyrmion interactions and may prove essential in designing spintronic devices.

The predictability of expansion with Invisalign: A retrospective cohort study

Few studies have evaluated the predictability of expansion with Invisalign for the current SmartTrack material. Pretreatment, predicted, and posttreatment digital models from Invisalign's ClinCheck software were obtained for 57 adult patients with a planned arch expansion of at least 3 mm. Arch width measurements were collected using a software measuring tool (MeshLab), Invisalign's arch width table, and the centroid of the clinical crown. Data for 30 patients were remeasured for each method to assess intrarater reliability. Predictability of expansion was calculated by comparing the amount of achieved expansion to predicted expansion. The predictability of expansion across centroids for the maxillary teeth was: 72.2% canines, 78.9% first premolars, 81.1% second premolars, 63.5% first molars, and 41.5% second molars. The predictability of expansion across centroids for the mandibular teeth was: 82.3% canines, 93.0% first premolars, 87.7% second premolars, 79.8% first molars, and 42.9% second molars. The average expansion was significantly different from that predicted for each type of tooth in both the maxilla and mandible. Both underexpansion and overexpansion were observed. Arch width measurement reliability for each employed method was as follows: MeshLab (average error 0.197 mm); calculated centroids (0.002 mm); ClinCheck arch width table (0.000 mm). On average, the amount of predicted expansion is not achieved with the Invisalign system and varies according to tooth type and arch. Discretion is required when overcorrecting to compensate for expansion inaccuracy. Both underexpansion and overexpansion were observed; further investigation into factors influencing underexpansion and overexpansion is required.

Mechanical and thermal properties of Mo for packaging HgCdTe IRFPA detector at cryogenic temperatures

Molybdenum (Mo), as an electronic packaging material with excellent comprehensive performance, is widely used in the lead substrate and cold platform of HgCdTe infrared focal plane detector assembly. The thermodynamic parameters of molybdenum in the temperature ranging from 300 K down to 4.2 K are obtained by the thermodynamic tests in this paper. Mechanical properties and microstructure of Mo at 300 K, 77 K and 4.2 K are analyzed with the use of tensile tester and scanning electron microscope. Results show that: the average linear expansion coefficient of molybdenum between 300 K and 4.2 K is 3.21 × 10-6 /K, and molybdenum has the properties of high thermal conductivity and low specific heat capacity at cryogenic temperature. The elastic modulus of molybdenum increases, and the tensile strength and elongation decrease with decreasing temperature in the temperature ranging from 300 K down to 4.2 K. According to the macroscopic and microscopic morphology of tensile fracture, the fracture mode at 300 K is the ductile–brittle mixed fracture mode, and the material turns from ductile at 300 K to brittle at 77 K and 4.2 K. The fracture behaviors are transgranular fracture at 77 K and intergranular fracture at 4.2 K, respectively.

Mapping urban land dynamics by automatic generation of ground samples from Globeland30 and random forest classification on the Google Earth Engine†

Long time series urban mapping using Landsat images remains challenging due to the difficulty of collecting representative ground samples. We proposed a mapping approach integrating a sample-transferring scheme, multiple-feature fusion classification, and temporal filtering to generate annual urban land maps in Zhengzhou during 1986 to 2021 with the aid of the Google Earth Engine (GEE). The training and validation samples for each historical year were obtained by a proposed sample transfer scheme based on stable areas derived from the GlobeLand30 datasets. Thirteen variables, such as spectral indices, spectral bands, and terrain factors, were combined to form the feature vector. Annual classification was conducted yearly using the random forest algorithm on GEE to obtain annual impervious surface (ISs) maps. Finally, the IS classification maps were postprocessed to obtain the final urban land maps. Zhengzhou was selected as the study area due to its dramatic urbanization in recent decades. The results showed that the overall accuracy and Kappa coefficient of the IS classification maps ranged from 0.8888 to 0.9578 and 0.6548 to 0.8331, respectively. Compared with other 30-m land-cover products, our urban land maps showed higher accuracy and more reliable spatial details. The proposed approach can generate massive ground samples for long time series urban mapping and is helpful for updating regional and global land-cover products. Zhengzhou’s urban area increased by 1423.24 km2 with an average expansion area of 40.66 km2 / year from 1986 to 2021. The urban expansion in Zhengzhou showed significant stage characteristics and spatial variations. The expansion intensity indices were 0.204, 0.404, 0.736, and 2.018, respectively, at four time periods and varied across the 12 regions in Zhengzhou.

Towards a multitracer timeline of star formation in the LMC – II. The formation and destruction of molecular clouds

ABSTRACT The time-scales associated with various stages of the star formation process represent major unknowns in our understanding of galactic evolution, as well as of star and planet formation. This is the second paper in a series aiming to establish a multitracer timeline of star formation in the Large Magellanic Cloud (LMC), focusing on the life cycle of molecular clouds. We use a statistical method to determine a molecular cloud lifetime in the LMC of $t_{\text{CO}}=11.8^{+2.7}_{-2.2}$ Myr. This short time-scale is similar to the cloud dynamical time, and suggests that molecular clouds in the LMC are largely decoupled from the effects of galactic dynamics and have lifetimes set by internal processes. This provides a clear contrast to atomic clouds in the LMC, of which the lifetimes are correlated with galactic dynamical time-scales. We additionally derive the time-scale for which molecular clouds and H ii regions co-exist as $t_{\text{fb}}=1.2^{+0.3}_{-0.2}$ Myr, implying an average feedback front expansion velocity of 12 km s−1, consistent with expansion velocities of H ii regions in the LMC observed directly using optical spectroscopy. Taken together, these results imply that the molecular cloud life cycle in the LMC proceeds rapidly and is regulated by internal dynamics and stellar feedback. We conclude by discussing our measurements in the context of previous work in the literature, which reported considerably longer lifetimes for molecular clouds in the LMC, and find that these previous findings resulted from a subjective choice in timeline calibration that is avoided by our statistical methodology.

Geospatial Intelligence and Machine Learning Technique for Urban Mapping in Coastal Regions of South Aegean Volcanic Arc Islands

Coastal environments are globally recognized for their spectacular morphological characteristics as well as economic opportunities, such as fisheries and tourism industries. However, climate change, growth in tourism, and constant coastal urban sprawl in some places result in ever-increasing risk in the islands of the South Aegean Volcanic Arc (SAVA), necessitating thoughtful planning and decision making. GEOspatial INTelligence (GEOINT) can play a crucial role in the depiction and analysis of the natural and human surroundings, offering valuable information regarding the identification of vulnerable areas and the forecasting of urbanization rates. This work focuses on the delineation of the coastal zone boundaries, semi-automatization of Satellite-Derived Bathymetry (SDB), and urban mapping using a machine learning algorithm. The developed methodology has been implemented on the islands of Thira (Santorini island complex) and Milos. This study attempts to identify inaccuracies in existing open-source datasets, such as the European Settlement Map (ESM), as a result of the unique combination of the architectural style and bare-soil characteristics of the study areas. During the period 2016–2021, the average accuracy of the developed methodology for urban mapping in terms of the kappa index was 80.15% on Thira and 88.35% on Milos. The results showed that the average urbanization expansion on specified settlements was greater than 22% for both case studies. Ultimately, the findings of this study could contribute to the effective and holistic management of similar coastal regions in the context of climate change adaptation, mitigation strategies, and multi-hazard assessment.

Spatial-Temporal Pattern Evolution of Xi’an Metropolitan Area Using DMSP/OLS and NPP/VIIRS Nighttime Light Data

A metropolitan area provides valuable space for economic development, and it is the home on which human beings depend for their survival. However, metropolitan areas are often faced with prominent problems caused by the natural environment and city layout. Therefore, understanding metropolitan areas’ spatial-temporal pattern evolution is of vital significance for medium-to-long-term city growth. This study uses the nighttime light data to monitor the urban pattern evolution of the Xi’an Metropolitan Area (XMA) over the past 30 years. The study results suggest that the continuity correction and consistency correction used in this study can construct a stable long-term, multi-source nighttime light dataset and, at the same time, accurately reflect the changes in the urban pattern. The determination coefficient between gross domestic product (GDP) and total nighttime light (TNL) reached 0.90; the nighttime light index (NLI) of the XMA is characterized by high spatial heterogeneity. The NLI of the core areas has been saturated before 2004, while the CNLI value of the peripheral Chang’an District was 0.31 by 2021. Urban land expanded in all directions, with an average expansion rate of 12.9% and an expansion intensity of 2.6%. The nighttime light gravity center generally shifted towards southwest, from (108.915° E, 34.355° N) in 1992 to (108.922° E, 34.343° N) in 2021. The urban pattern of the metropolitan area is influenced by the natural environment, and the southwest and northeast directions will be the primary development directions in the future. The local development policy is a crucial driving factor in the urban pattern evolution, which significantly affects the location and intensity of urban expansion; the center of gravity of the XMA has different migration directions in different periods, meaning that the development of the metropolitan area tends to be balanced.

Reinterpretation of the Geldart A powder classification based on Eulerian–Eulerian CFD simulation

Abstract Geldart classified powders into four categories and assigned each category its own unique characteristic. Geldart A particles, being easily aeratable, show a unique feature of ‘Homogenous expansion’ before bubbling. In this work, an additional feature for the Geldart chart is proposed which adds significant utility for the processing of Geldart A particles. CFD was used to characterize the entire Geldart A region of the Geldart chart based on detailed fluidization behavior. For this, Eulerian–Eulerian Two-fluid model (TFM) simulations were conducted for 25 particle systems across the entire span of the Geldart A region. The simulations (Solid volume fraction (SVF) contours) of bed evolution, taken before the appearance of multiple bubbles, were analyzed in detail. The particle systems were then sub-categorized into Red (5% average bed expansion), Orange (12.5% average bed expansion), and Green (30% average bed expansion) sub-types. The sub-types were plotted on Geldart chart, and for the first time a continuum heat map was generated, from which the ‘level of fluidizability’ of all Geldart A powders can be conveniently gaged. The map can be used for a more informed choice of powder for various industrial applications. Also, the A/B boundary proposed by Verloop was found to be a better fit for our proposed continuum when compared to the original Geldart A/B boundary. The 2D Simulation results performed in this work, found adequate validation against experimental findings in literature. Further, fine mesh 2D simulation results compared well with 3D simulations for dense bed, and were thereby deemed adequate for revealing dense bed behavior before onset of multiple bubbles.

IDENTIFKASI KERUSAKAN LAHAN HUTAN AKIBAT AKTIVITAS PERTAMBANGAN EMAS DESA BOWONE KECAMATAN TABUKAN SELATAN TENGAH

The problem of this research is changes in forest land use and the level of damage to forest land due to gold mining activities in Bowone Village, South Central Tabukan District, Sangihe Islands Regency. The research method is quantitative with GIS-based spatial analysis using Supervised Classification and NDVI. The study results show that the mining area expanded from 11.83 hectares in 2015 from 2.35 hectares to 14.18 hectares in 2020, with an average expansion of 2.37 hectares per year or 45.53% per year. Heavy damage in the forest area of ​​Bowone Village with an area of ​​131.2422 hectares (15%). Moderate damage with an area of ​​279,8941 hectares (35%), and light damage with an area of ​​435,7669 hectares (51.45). The condition of forest land cover in Bowone village is categorized as quite reasonable. However, it should be noted and anticipated that the current state of vegetation cover may decrease because 279.8941 hectares (33.05) have experienced a medium density category.