Adjacent Zones Research Articles

Energy analysis of a wood or pellet stove in a single-family house equipped with gas boiler and radiators

In the residential sector, biomass appliances are widely used for space heating and often combined with other systems. This work aims at comparing the final and primary energy consumption of different configurations, including a conventional and a ducted pellet stove and a wood log stove using air as heat transfer fluid. A dynamic analysis of the interaction between biomass stoves and conventional heating systems, such as gas boilers and radiators, is carried out within a typical single-family house in a mild climate, using TRNSYS software. In addition, natural ventilation of the building is considered using CONTAM, with a focus on external infiltrations and internal air circulation due to the buoyancy effect. Results show that the biomass device in one room promotes the airflows between adjacent thermal zones, enhancing the heat distribution through door openings, in particular when an air ducted stove is present. The final energy consumption resulting from simulations with wood-burning stoves is 21% higher than pellet stoves. The pellet stove results in similar final energy and a 30% increase in overall primary energy, while the wood stove increases the final energy by 22% and approximately 40% of overall primary energy compared to the case of a traditional gas system coupled to radiators which is considered as reference. Nevertheless, non-renewable primary energy savings are higher than 50% with pellet stoves and 60% with wood-log stoves.

The Paleogene Gosau Group Slope Basins of the Incipient Eastern Alpine Orogenic Wedge: A Case Study at the Gams Basin (Austria)

This study investigates the Paleogene deep-water depositional system of the Gosau Group at Gams, Styria (Austria). The examined sections of the Danian to the Ypresian age (NP1–NP12) comprise sediments of the Nierental and Zwieselalm Formations. Four deep-water clastic facies assemblages were encountered: (1) pelagic marls with thin turbidites, (2) carbonate-rich turbidites, (3) carbonate-poor turbidites, and (4) marl-bearing turbidites; slump beds and mass flow deposits are common features in all facies assemblages. Based on heavy mineral, thin section, microprobe, and paleoflow analyses, provenance was from the surrounding Northern Calcareous Alps (NCA) rocks and exhuming metamorphic Upper Austroalpine units to the south. In addition, biogenic calcareous material was delivered by adjacent contemporaneous shelf zones. The sedimentary depocenter was situated at the slope of the incipient Alpine orogenic wedge, in frontal parts of the NCA, facing the subducting Penninic Ocean/Alpine Tethys. The evolution of the Gams Basin was connected to the eoalpine and mesoalpine orogeny and the adjunctive transpressional setting. The Gams deep-water depositional system is interpreted as an aggrading or prograding submarine fan, deposited into a small confined slope basin, positioned along an active continental margin, bound and influenced by (strike-slip) faults, related to crustal shortening. The development of the Gams slope basin and its infilling sequences was mainly dominated by tectonism and sediment supply, rather than by eustatic sea-level fluctuations. The basin was cut off during the Eocene due to renewed orogeny. A Quaternary analogue for the Upper Cretaceous to Paleogene basin setting of the Gams area is represented by the Santa Monica Basin in the California Continental Borderland.

Udurchukan formation and ayakit complex (Bureya massif, Sikhote-Alin): location, age and geochemistry

Neogene basalts in the eastern of the Bureya massif and the adjacent Kursk-Komsomolskaya zone of the Sikhote-Alin fold system occur in the seismically and tectonically active area along the Khingan, Amgun and Tanlu-Kharpi deep faults. Analysis of age constraints on the timing of basaltoid magmatism in the Miocene suggests three phases of magmatism in the study areas: Early Miocene (Udurchukan Formation: 22,6–18,6 Ma); Middle Miocene (Ayakit Complex: 14,8–13,0 Ma), and Late Miocene (Ayakit Complex: 10,0–9,3 Ma). Rock studies have found that basalts (Ayakit plateau), basaltic andesites (Udurchukan plateau), and leucitites (Yadasen Island) are enriched in sodium oxides, potassium, titanium, iron, magnesium, and phosphorus. Two samples of alkaline olivine basalts from the Ayakit plateau yielded high KkTe (578,0) and Ag (172,7); elevated Kk in high field-strength Nb (6,2), Ta (3,4) and radioactive Th (2,7), U (2,4). The contents of Co, Ni, Zr, Mo, W, Zn, Sr, Ba, Hg, light and middle REE are 1,1–1,5 times or even higher than the clarke values for mafic rocks. There is a slight deficit of Sb, Cs, Bi, Cu, Li, Sc, Rb, Tm, Yb, Lu (Kk < 0,7). A similar chemical composition of the SASS basalts (Solnechny settlement and Yadasen Island) suggests that they have a common magma source.

Unraveling ecological risk of As/Sb and other metal(loid)s and fungal community responses in As/Sb smelting-intensive zone: A typical case study of Southwest China

Compound metal(loid)s are always occurred adjacent smelting-intensive zone. However, little is known with respect to the relative influences of As/Sb and other metal(loid)s on human health and fungal communities as a consequence of the chronic As/Sb smelting fabrication. Our objectives were to determine the ecological impacts of the occurrences of As/Sb and other metal(loid)s on human health and fungal communities via diverse indices and Internal Transcribed Spacer (ITS) sequencing in this study. Three vegetated soils exhibited exceptional metal(loid)s enrichment of As, Sb, Cr, Ni, Zn, Mn, Cu and Pb. Higher health risks of As, Sb and Pb were observed in all soils, accounted for over 80% of total health risk. ITS sequencing revealed that fungal communities among three vegetated soils were significantly different in their structures and compositions, and the metal(loid)s types and contents contributed differently to the variations. Fungal community in forest soil was mainly influenced by metal(loid)s, while in maize and rice soil were associated with pH, TC, TOC, TN and TP. Fungal communities were dominated by Ascomycota, followed by Mortierellomycota and Basidiomycota. Linear Discriminate Analysis Effect Size (LefSe) analysis revealed that tolerant taxa affiliated with distinct phylogenetic lineages were vegetation-specific. 25 potential keystone fungal taxa were identified mainly belonged to Dothideomycetes, Orbiliomycetes and Saccharomycetes. Our results may serve as a model for similar metal(loid)s contaminated areas and provide theoretical guidances for bioremediation of metal(loid)s pollution.

Relationship of Microvascular Obstruction with Global and Regional Myocardial Function Determined by Cardiac Magnetic Resonance after ST-Segment Elevation Myocardial Infarction

ObjectiveTo investigate the impact of microvascular obstruction (MVO) on the global and regional myocardial function by cardiac magnetic resonance feature-tracking (CMR-FT) in ST-segment-elevation myocardial infarction (STEMI) patients after percutaneous coronary intervention. MethodsConsecutive acute STEMI patients who underwent cardiac magnetic resonance imaging 1 - 7 days after successful reperfusion by percutaneous coronary intervention treatment were included in this retrospective study. Based on the presence or absence of MVO on late gadolinium enhancement images, patients were divided into groups with MVO and without MVO. The infarct zone, adjacent zone, and remote zone were determined based on a myocardial 16-segment model. The radial strain (RS), circumferential strain (CS), and longitudinal strain (LS) of the global left ventricle (LV) and the infarct, adjacent, and remote zones were measured by CMR-FT from cine images and compared between patients with and without MVO using independent-samples t-test. Logistic regression analysis was used to assess the association of MVO with the impaired LV function. ResultsA total of 157 STEMI patients (mean age 56.66 ± 11.38 years) were enrolled. MVO was detected in 37.58% (59/157) of STEMI patients, and the mean size of MVO was 3.00 ±3.76 mL. Compared with patients without MVO (n = 98), the MVO group had significantly reduced LV global RS (t = −4.30, P < 0.001), global CS (t = 4.99, P < 0.001), and global LS (t = 3.51, P = 0.001). The RS and CS of the infarct zone in patients with MVO were significantly reduced (t = −3.38, P = 0.001; t = 2.64, P = 0.01; respectively) and the infarct size was significantly larger (t = 8.37, P < 0.001) than that of patients without MVO. The presence of LV MVO [OR = 4.10, 95%CI: 2.05 – 8.19, P < 0.001) and its size [OR = 1.38, 95% CI: 1.10–1.72, P=0.01], along with the heart rate and LV infarct size were significantly associated with impaired LV global CS in univariable Logistic regression analysis, while only heart rate (OR=1.08, 95%CI: 1.03 – 1.13, P=0.001) and LV infarct size (OR=1.10, 95%CI: 1.03 - 1.16, P=0.003) were independent influencing factors for the impaired LV global CS in multivariable Logistic regression analysis. ConclusionThe infarct size was larger in STEMI patients with MVO, and MVO deteriorates the global and regional LV myocardial function.

Generation Mechanisms of Mesoscale Eddies in the Mauritanian Upwelling Region

AbstractThe physical processes driving the genesis of surface- and subsurface-intensified cyclonic and anticyclonic eddies originating from the coastal current system of the Mauritanian upwelling region are investigated using a high-resolution (∼1.5 km) configuration of GFDL’s Modular Ocean Model. Estimating an energy budget for the boundary current reveals a baroclinically unstable state during its intensification phase in boreal summer and which is driving eddy generation within the near-coastal region. The mean poleward coastal flow’s interaction with the sloping topography induces enhanced anticyclonic vorticity, with potential vorticity close to zero generated in the bottom boundary layer. Flow separation at sharp topographic bends intensifies the anticyclonic vorticity, and submesoscale structures of low PV coalesce to form anticyclonic vortices. A combination of offshore Ekman transport and horizontal advection determined the amount of South Atlantic Central Water (SACW) in an anticyclonic eddy. A vortex with a relatively dense and low PV core will form an anticyclonic mode water eddy, which will subduct along isopycnals while propagating offshore and hence be shielded from surface buoyancy forcing. Less contribution of dense SACW promotes the generation of surface anticyclonic eddies as the core is composed of a lighter water mass, which causes the eddy to stay closer to the surface and hence be exposed to surface buoyancy forcing. Simulated cyclonic eddies are formed between the rotational flow of an offshore anticyclonic vortex and a poleward flowing boundary current, with eddy potential energy being the dominant source of eddy kinetic energy. All three types of eddies play a key role in the exchange between the Mauritanian coastal currents system and the adjacent eastern boundary shadow zone region.

Tree use by koalas after timber harvesting in a mosaic landscape

Context A better understanding of how individual animals use their habitat after disturbance can help optimise management practices for their conservation. Forestry is one such disturbance for koalas that operates under regulations based on best available information to minimise impacts. Aims This study aimed to investigate tree use by koalas in a mosaic of young, regenerating trees after timber harvest and mature trees in adjacent exclusion zones. Methods Tracking collars using very high frequency radio and Global Positioning System transmitters were used to track 10 koalas (five males, five females) across all seasons in three forests, 5–10 years after timber harvesting as regulated by practices current at that time. Tree use was compared to availability based on basal area in different parts of the forest. Key results We tracked koalas to 429 day-trees and 70 night-trees during this time. Males and females displayed little difference in tree use. Blackbutt Eucalyptus pilularis and turpentine Syncarpia glomulifera were the most commonly used species during the day, but blackbutt was ranked with the highest preference relative to tree availability. Tallowwood Eucalyptus microcorys was by far the most commonly used tree at night. Koalas used a broad range of tree sizes during the day and night, but most often used medium-sized trees, with preferences for a diameter of 30–60 cm (slightly smaller at night). Koalas used all topographic positions in the landscape, but more than half of the trees used were in lower topographic areas (gullies and lower slopes). Areas mapped as having previous heavy timber harvesting were the most used forest category, followed by riparian exclusion zones. Conclusions Our results demonstrate that koalas commonly used trees regenerating after harvest, although preferences for medium-sized trees and tallowwood as a night browse tree suggest current forestry regulations can be fine-tuned by retaining a greater proportion of these features. Implications Because most trees were used only once, our results support the view and current practice of retaining habitat patches, such as exclusion zones and wildlife clumps (triggered by a koala habitat model), to provide a mix of species and size classes for both food and shelter. A review of tree size and species retention is recommended.

Microstructural characterisation of thick-walled wire arc additively manufactured stainless steel

• Microstructural features of a thick-walled WAAM stainless steel part are investigated. • Microstructure exhibits periodically repeating characteristics across the WAAM part. • Oriented and textured structure with large grains at the overlapping region of adjacent fusion zones. • Significant spatial variations in terms of fusion zone shape, grain structure, texture, and phases. Wire arc additive manufacturing (WAAM) is a class of technologies suitable for producing large parts due to its high material deposition and building rates. Among the many possible materials processed by WAAM, austenitic stainless steels, e.g. 316L, are commonly employed. The structure of WAAM 316L thin parts has been studied extensively before. However, multiwalled or thick WAAM 316L parts remain largely unexplored. Hence, in this study, the microstructure of a thick 316LSi WAAM part is characterised in detail. The microstructure of the part consists of large and highly-oriented columnar grains dominated by epitaxial and competitive growth. The overlapping regions between neighbouring fusion zones contain long grains with a dominant <100> texture, which cross several layers and are aligned with the building direction. The grains' internal microstructure consists of an austenite matrix, ferrite with locally varying dendritic morphologies and dispersed oxide inclusions. The texture spatially varies across the part, and this variation is correlated to the local thermal gradient induced by the building strategy and processing conditions used during the manufacturing of the thick-walled part.

Verbs of hiding: A typology of systems

The article examines the lexicalization of the semantic domain of hiding from a typological perspective. Prototypically, hiding assumes that the subject puts the object out of sight of some other person. This event may however be colexifi ed with situations that deviate from the prototype in one way or another, e.g., by having a non-canonical object (an abstract entity instead of a concrete thing, cf. ‘to hide one’s thoughts’) or a non-canonical purpose (protecting the object from external impact instead of concealing it from someone’s view, cf. ‘to hide the face from the sun’). Based on the data of 28 languages, we first compare the core verbs of hiding. The cross-linguistic variation in their meanings constitutes a basis for a typological classifi cation of lexical systems in the hiding domain. Second, we turn to peripheral verbs of the field and show that they frequently come from adjacent semantic zones, e.g., those of covering, removing or keeping in a certain place. This pattern can be traced both in a synchronic and a diachronic perspective. The use of these verbs with reference to hiding events calls into question the traditional notions of semantic field and metonymic shift.

Terahertz metasurface zone plates with arbitrary polarizations to a fixed polarization conversion

Metasurfaces that can realize the polarization manipulation of electromagnetic waves on the sub-wavelength scale have become an emerging research field. Here, a novel strategy of combining the metasurface and Fresnel zone plate to form a metasurface zone plate is proposed to realize the conversion from nearly arbitrary polarizations to a fixed polarization. Specifically, when one polarized wave is incident on adjacent ring zones constructed by different types of meta-atoms, the transmitted waves generated by odd-numbered and even-numbered ring zones converge at the same focus and superimpose to generate a fixed polarized wave. As function demonstrations, we have designed two types of metasurface zone plates: one is a focused linear polarizer, and the other can convert nearly arbitrary polarized waves into focused circularly polarized waves. The simulated and measured results are consistent with theoretical expectations, suggesting that the proposed concept is flexible and feasible. Our work provides an alternative platform for polarization manipulation and may vigorously promote the development of polarization photonic devices.

Strong Upper‐Plate Heterogeneity at the Hikurangi Subduction Margin (North Island, New Zealand) Imaged by Adjoint Tomography

AbstractWe use earthquake‐based adjoint tomography to invert for three‐dimensional structure of the North Island, New Zealand, and the adjacent Hikurangi subduction zone. The study area, having a shallow depth to the plate interface below the North Island, offers a rare opportunity for imaging material properties at an active subduction zone using land‐based measurements. Starting from an initial model derived using ray tomography, we perform iterative model updates using spectral element and adjoint simulations to fit waveforms with periods ranging from 4–30 s. We perform 28 model updates using an L‐BFGS optimization algorithm, improving data fit and introducing P‐ and S‐wave velocity changes of up to ±30%. Resolution analysis using point spread functions show that our measurements are most sensitive to heterogeneities in the upper 30 km. The most striking velocity changes coincide with areas related to the active Hikurangi subduction zone. Lateral velocity structures in the upper 5 km correlate well with New Zealand geology. The inversion reveals increased along‐strike heterogeneity on the margin. In Cook Strait we observe a low‐velocity zone interpreted as deep sedimentary basins. In the central North Island, low‐velocity anomalies are linked to surface geology, and we relate velocity structures at depth to crustal magmatic activity below the Taupō Volcanic Zone. Our velocity model provides more accurate synthetic seismograms with respect to the initial model, better constrains small (50 km), shallow (15 km) and near‐offshore velocity structures, and improves our understanding of volcanic and tectonic structures related to the active Hikurangi subduction zone.

Структурная энтропия как мера фракционирования массопотоков в экосистемах в условиях транспортного прессинга

The features of the distribution of polycyclic aromatic hydrocarbons considered as geochemical markers of mass transfer in the structural transitions of «snow–soil–plants» of urban soil-plant systems are analyzed. The expe-rimental impact test site is an area with an intensive transport press – the RUDN campus with an adjacent green zone (south–western district of Moscow). Spatial variability of polyarenes in media and structural transitions is chaotic. Cal-culations of polyarene emissions from fuel combustion, tire abrasion, brake pads and asphalt have been carried out. Such an «overlay» of pollution from external sources contributes to the intensive chaoticization of structural transitions in the designated system. The role of extensive parameters (entropy increments, Gibbs energy, enthalpy) in media and various structural transitions is estimated. The wave nature of the impact of motor vehicles as sources of pollution is emphasized. Informative parameters of the fractionation of the polyarene complex are the dependences of the increment of structural entropy on the translocation coefficients in the interacting components. The thermodynamic apparatus makes it possible to identify the factors and mechanisms that determine the accumulation of polyarenes in natural and transport-loaded conditions. Mobile and neutral pools of migrating polyarenes in the soil-plant system were identified by grouping methods. The analysis of migration in the nonequilibrium system «snow–soil–plant roots – stems» using the principles of thermodynamics revealed the chaotic processes of migration and accumulation. The leading role in the structuring of polyarene flows in the above system is assigned to the rhizosphere. Based on the variability of thermody-namic parameters, the concept of structural flowability of systems is introduced. The introduction of the concept makes it possible to objectify the procedure for assessing the intensity of anthropogenic loads and to identify areas of the soil-plant system with maximum accumulation and with maximum «throughput» in relation to polyarenes.

Hydrodynamic and sediment transport modelling in the Pearl River Estuary and adjacent Chinese coastal zone during Typhoon Mangkhut

Typhoon Mangkhut, in 2018, was one of the worst typhoons in recent history that has made landfall in the Pearl River Estuary (PRE) China. It swept along the coast of Guangdong Province, causing severe damage to many areas and affecting more than one million people. To study the hydrodynamics and sediment dynamics in different sub-regions of the PRE during the typhoon, we implemented a 3D wave-current-sediment coupled ocean model based on the Semi-implicit Cross-scale Hydroscience Integrated System Model (SCHISM). A series of numerical experiments were conducted to study the variation in suspended sediment concentration (SSC) under different external forcing mechanisms, including tides, waves, river discharges and strong winds. Moderate Resolution Imaging Spectroradiometer (MODIS) images, collected after the typhoon landed, were used to assess the simulation results. We found that in the area where the water depth was shallower than 20 m, the increased total suspended sediment concentration was dominated by the regional erosion of fine sediment which was caused by near-bottom wave orbital velocity and bottom shear stress, especially at the four western outlets and along the western coast of the PRE. For the deeper coastal zone, at depths between 20 and 30 m offshore of the western coast, the high total SSC resulted from the contribution of fine sediment transported from the upper and middle estuaries by southwestward advection. A small amount of sand eroded and migrated locally, owing to the corresponding increase in the bottom shear stress. The variation in SSC during the typhoon had a time lag compared with other dynamic conditions, resulting in a maximum 1 h delayed response after the typhoon made landfall. Based on the results of the sensitivity experiments under the same typhoon conditions, we found that, as a result of wave-enhanced bottom shear stress, the SSC values associated with wave-current interaction were significantly higher, by as much as 1.5 and 1.3 times those of simulations without the waves at the surface and near-bottom layers, respectively. This indicated that the sediment resuspension induced by waves was important during typhoon landfall. However, the strong wind-induced current was weakened owing to the joint effect of wave radiation stress and enhanced bottom stress; thus, considering wave effects, the magnitude of the resulting sediment transport rate was smaller than that without considering wave effects, especially in shallow waters. During the approach, landfall and retreat of Typhoon Mangkhut, Lingding Bay experienced two transitions from a slight state of sediment loss to a relatively high state of sediment gain, followed by an even greater state of sediment loss. During an M2 tidal cycle after Typhoon Mangkhut made landfall, the net seaward suspended load sediment transport in Lingding Bay reached 0.37 megatonnes. For the typhoon period covering three M2 tidal cycles, the overall state of suspended load sediment transport in Lingding Bay was sediment loss, with the magnitude of sediment loss on the west side being larger than that of sediment gain on the east side. The magnitude of the overall sediment loss in Lingding Bay would be enlarged unrealistically by approximately 73% if the wave effects were excluded. In each period, the extent of sediment transport between the two sides of the bay was strengthened by the wave-current interaction under typhoon conditions. We determined that the net effect of wave-current interaction and strong wind-induced currents under typhoon conditions was a key factor for erosion, which resulted in SSC-influenced areas being approximately 8.7 and 4.4 times as large as those under normal weather conditions for the surface and near-bottom layers, respectively. The turbidity maximum moved from the West Shoal of Lingding Bay under normal weather to the Modaomen Estuary, which was the most affected area during the typhoon when wave effects were considered. We also showed that the relative location of the typhoon path with respect to the estuary had a more significant effect on erosion than the intensity of the typhoon.

ЭКОЛОГИЧЕСКИЙ ПОТЕНЦИАЛ АДМИНИСТРАТИВНЫХ ГРАНИЦ

In European Russia, administrative borders form adjacent zones of the rural population decline, favorable for conservation of natural landscape, its wild flora and fauna. The article discusses the types and functions of administrative borders along with their applicability to serve as axes of green econet corridors.

Experimental Studies of the Heat Exchange Between the Water Film and the Casting Roller in the Thermal Preconditioning Chamber

When the casting roller is cooled or heated in the preconditioning chamber the water is supplied to its surface by flat-jet nozzles. The visual inspection of the model of the casting roller showed that a considerable part of it can be covered with the water film spreading from sprinkling zones. It was established that the heat conductivity in the roller body is considered to be a crucial thermal preparation factor in the conjugate heat-exchange problem for the roller of a large diameter at Bio criterion values exceeding 20. Hence, it is sufficient to provide an essential level of the heat transfer that corresponds to the heat transfer coefficient of 2000 W/(m2∙K) to provide appropriate operating conditions for the thermal preparation of the roller. The conditions are also met in sprinkling zones. Due to this fact this scientific paper studies the heat exchange conditions under the water film that spreads between the adjacent sprinkling zones. A range of changes in the flow rate of the spreading water film was determined experimentally. The conditions of heat exchange between the surface of alpha-calorimeter and the water film were analyzed depending on its flow rate and the heat meter surface temperature. A generalized correlation equation was derived. It was established that the heat exchange intensity in sprinkling zones and under the spreading water film meets technological roller treatment conditions in the preconditioning chambers. The obtained research data can be used for the rational arrangement of the collectors and flat-jet nozzles in casting roller preconditioning chambers to reduce the cold and hot water consumption and cut down operating costs.

Inter-Zone Differences of Convective Development in a Convection Outbreak Event over Southeastern Coast of China: An Observational Analysis

Among the densely-populated coastal areas of China, the southeastern coast has received less attention in convective development despite having been suffering from significantly increasing thunderstorm activities. The convective complexity under such a region with extremely complex underlying and convective conditions deserves in-depth observational surveys. This present study examined a high-impact convection outbreak event with over 40 hail reports in the southeastern coast of China on 6 May 2020 by focusing on contrasting the convective development (from convective initiation to supercell occurrences) among three adjacent convection-active zones (north (N), middle (M), and south (S)). The areas from N to S featured overall flatter terrain, higher levels of free convection, lower relative humidity, larger convective inhibition, more convective available potential energy, and greater vertical wind shears. With these mesoscale environmental variations, distinct inter-zone differences in the convective development were observed with the region’s surveillance radar network and the Himawari-8 geostationary satellite. Convection initiated in succession from N to S and began with more warm-rain processes in N and M and more ice-phase processes in S. The subsequent convection underwent more vigorous vertical growth from N to S. The extremely deep convection in S was characterized by the considerably strong precipitation above the freezing level, echo tops of up to 18 km, and a great amount of deep (even overshooting) and thick convective clouds with significant cloud-top glaciation. Horizontal anvil expansion in convective clouds was uniquely apparent over S. From N to S, more pronounced mesocyclone and weak-echo region signatures indicated high risks of severe supercell hailstorms. These results demonstrate the strong linkage between the occurrence likelihood of severe convection and associated weather (such as supercells and hailstones) and the early-stage convective development that can be well-captured by high-resolution observations and may facilitate fine-scale convection nowcasting.

Enhancement of wavefront measurement sensitivity in a zonal wavefront sensor without curtailing the sensing speed

In this paper we propose a zonal wavefront sensing scheme that facilitates wavefront measurement with enhanced sensitivity at the standard video rate. We achieve this enhanced sensitivity by implementing a sequential display of binary holograms described over each zone sampling the incident wavefront with the help of a ferroelectric liquid crystal spatial light modulator. By keeping the number of active zones as 24 and using a camera with an imaging frame rate equal to the binary hologram display rate of the spatial light modulator, we are able to reach a sensing frame rate of 60 Hz. In addition to enhanced sensitivity, the proposed scheme facilitates zone-wise tuning of binary holograms and eliminates the possibility of any crosstalk between adjacent zones. We perform a proof-of-principle experiment that validates the proposed zonal wavefront sensing scheme and demonstrates its advantages.

Diffusional evolution of σ-phase to resolve a long-standing dissimilar material joining issue in supercritical boiler

ABSTRACT To restore sustainable growth in thermal power plant operation in view of energy efficiency perspective vis-à-vis an environment-friendly technological advancement, we hereby successfully develop a novel technological route of joining dissimilar steels in a supercritical boiler using GTAW process with Nickel-based filler containing chromium. In its most fundamental conceptualisation, the diffusion of chromium from the molten weld pool to adjacent heat-affected zone (HAZ) results in an evolution of σ-phase (in a region of 52 µm width), which, in turn, arrests grain boundary sliding at boiler operation temperature so as to resist failure. This phenomenon is judiciously established in this work by performing one of the most critical tasks of ascertaining tensile properties at the service temperature of the supercritical boiler followed by necessary characterisation of the weldment. This is further substantiated with an error-function-based analytical diffusion treatment. The high-temperature tensile failure through the base metal region (not through HAZ) with significant property (UTS = 332 MPa, %Elongation = 21) eventually indicates towards a hundred percent joint efficiency, thereby envisaging a sustainable techno-scientific advancement aided by diffusional evolution of σ-phase.

Squeeze cementing: Invasion of a yield stress suspension into a pore

Squeeze cementing is a process of fundamental importance in oil & well operations, in which cement slurry is injected under pressure into void spaces in defective sections of a wellbore, The aim is to isolate the borehole from adjacent geological zones and repair defects in the existing cement sheath, e.g. cracks, debonding and micro-annuli. Although cement slurries are often considered a homogeneous fluid, on the scales of relevance the multiphase nature of the cement slurry becomes relevant. In this context, we propose a model in which the cement slurry is considered as a viscoplastic suspension, in which both rheological and particle migration effects can be investigated. This allows us to explore different stoppage mechanisms, that combine bulk yield stress effects, enhancement by the solids fraction and modification by particle migration. Our approach is a continuum model based on the suspension balance model. We use this to model slurry penetration in long ducts, driven by a constant pressure difference. As well as a starting point for a more complex process model, our model provides insight into how shear induced migration combines with yield stress effects to produce non-monotone solids distributions adjacent to plug regions.

Food supplementation as a conservation intervention: A framework and a case of helping threatened shorebirds at a refuelling site

Supplemental feeding to mitigate the effects of food shortages may in some cases provide critical help to species conservation. However, supplemental feeding may have both positive and negative effects on wildlife and the environment. A scientifically designed feeding project helps to achieve conservation targets and reduces adverse effects. Here, we summarize a three-step framework for food supplementation that we used in practice: (1) determining whether supplemental feeding is required; (2) designing and implementing a practical feeding scheme; and (3) evaluating the effectiveness of food supplementation. We supplemented food for great knots (Calidris tenuirostris), an endangered migratory shorebird, at a recently impoverished refuelling site (Yalu Jiang estuary) in the Yellow Sea in spring 2018. The abundance of the staple food of great knots (Potamocorbula laevis, which had become very rare after 2012), was insufficient for the birds to refuel before the migratory flight to the breeding grounds. In our practical test, living P. laevis were collected in subtidal areas and transported to the intertidal area where great knots had been foraging in earlier years. The supplemented areas attracted 48% of all the great knots present in the 200 km2 study area. Nearly 90% of the supplemented food was consumed. Most great knots (>80%) foraged in the high-density supplementation zone where the densities of P. laevis were restored to the naturally occurring levels in 2011–2012. Here, food intake rates (mg AFDM/s) were 4.2 times those in the adjacent control zones. The framework and the feeding practice should help guide future supplemental feeding in a wide range of species.