Rich Zone Research Articles

Numerical study on the inner spray and combustion of active pre-chamber jet ignition for achieving higher performance of a hybrid engine under ultra-lean conditions

The mechanism of active pre-chamber (APC) inner fuel-air mixing, initial flame kernel formation, and jet flame evolution is still not clear. In this study, different APC inner geometry structures coulped with different mixture status were designed to synthetically analyze the inner gas flow, spray mixing, and hot jet flame evolution. The results showed that the APCs with small cone angles of 45° and 50° could promote the fuel-air mixing and spray atomization in a wider APC top space compared to APCs with large cone angles of 60° and 65°. An appropriate APC cone angle of 55° could reduce rich mixture zone and facilitate rapid flame kernel formation, fast flame propagation, and high jet activity, which was good for igniting the in-cylinder ultra-lean mixture. APCs with real fuel injection showed one heat release rate (HRR) peak, while APCs filled with homogeneous mixture showed the typical two peaks in the HRR profiles, the suitable mixture in APC duct section burned and formed the second HRR peak. The short thick APC induced the rich mixture distributed around the spark plug to form the initial flame kernel and showed a faster concentrated combustion process along with a higher pressure difference between APC and MC.

Morphological and Microbial Diversity of Hydromagnesite Microbialites in Lake Salda: A Mars Analog Alkaline Lake

ABSTRACTLake Salda, a terrestrial analog for the paleolake in Jezero Crater on Mars, hosts active, subfossil, and fossil hydromagnesite microbialites, making it an ideal location to study microbialite formation and subsequent processes. Our understanding of this record is still limited by an incomplete knowledge of the macro‐ and mesoscale morphotypes of microbialites, along with their spatial distribution and correlation with microbial and geochemical processes that influence microbialite formation. In this study, we investigated the spatial distribution, morphotypes, mineralogy, geochemistry, and microbial diversity of the microbialites and identified six distinct zones (Zone I to Zone VI) with major microbialite build‐ups in Lake Salda. Newly identified microbialites were classified based on the macro‐ and mesostructures. Our work shows that the lake contains stromatolites, thrombolites, stromatolitic thrombolites, dendrolites, and microbially induced sedimentary structures. At macroscale, Lake Salda microbialites exhibit hemispheres, stacked domes, and laterally linked columnar structures while minicolumns, knobs, mesoclots, laminae, and botryoidal structures are common at mesoscale. The macro‐ and mesoscale distribution of different microbialite types spatially correlates with microbial community composition and water depth. Deep‐growing microbialites with a low abundance of Cyanobacteria (∼1%–4%) and high abundance of Firmicutes (28%–93%) exhibit steeply convex lamination, producing finger‐like minicolumnar mesostructures. In contrast, shallow‐growing microbialites with a low abundance of Firmicutes (0%–5%) and high abundance of Cyanobacteria (11%–37%) have well‐preserved gently convex millimeter‐scale lamination, resulting in cauliflower mesostructures. Palygorskite ((Mg, Al)2Si4O10(OH)) is identified in the diatom‐rich microbial layer of the deep‐growing microbialites. Regardless of the microbialite types, hydromagnesite and aragonite are present in the extracellular polymeric substance (EPS)‐rich zone of the shallow and deep‐growing microbialites. Overall, environmental changes (e.g., water depth and, accommodation space) play a major role in the formation and spatial distribution of different microbialite morphologies at the macro‐ and mesoscale. Differences in the relative abundance of dominant microorganisms between mesostructured types suggest that mesomorphology may be influenced by changes in microbial diversity. Spatial variations in the microbialite morphotypes, along with the abundant presence of entombed biomass (e.g., mineralized filaments), may indicate areas that have a high potential for the preservation of biosignatures.

Earth Observation Data Utilisation for Rock Phosphate Exploration in Jhabua, Madhya Pradesh, India

ABSTRACT In this study, we processed Advanced Spaceborne Thermal Emission Reflection Radiometer (ASTER) data using partial subpixel mapping methods for delineating surface occurrences of fertilizer mineral i.e., phosphorite in dolomite and carbonate-bearing chert in the Aravalli Supergroup. We applied feature-oriented principal component analysis to derive an image composite for delineating the spatial extent of carbonate rich zones within the Lunaveda Group of rocks. Subsequently, we used image spectra of the surface exposure of rock phosphate of the existing mine at Khatama area as the reference for implementing adaptive coherence estimator (ACE) algorithm in the VNIR -SWIR bands of ASTER data to derive the abundance map of phosphorite. We confirmed the presence of phosphate in the identified phosphate anomaly zones during field surveys by implementing rapid colorimetric test that is proven for identifying the presence of phosphate in the samples. We also used the available surface geochemical data of P2O5 to establish the synergy between geochemical data and identified geochemical anomaly.

Stability of THAI in situ combustion process in reservoirs with layers of grading permeabilities and porosities: Detailed qualitative investigations

The world-wide reserves of heavy oil, tar sand, and bitumen, etc., outweigh those of conventional oil by a factor of 7/3. Given that the conventional reserves are being rapidly depleted, the need to develop and produce the unconventional resources has never been so critical. However, the proven most efficient and environmentally-friendly technology, namely the THAI process, still requires further study, and it has no documented design procedures that factor in the non-ideal geological features of heavy oil and bitumen reservoirs. Throughout the literature, there is little reported on the effects of gradations in reservoir petro-physical parameters on the performance of the THAI process. Consequently, this work reports the results of numerical simulations for four different kinds of reservoirs, each having progressive gradations in permeabilities and porosities. The major findings from this in depth study include.(i) In terms of the temperature distribution, regardless of the permeability and porosity gradations, the high temperature zone is always skewed towards the highest permeabilities and porosities zone. Furthermore, it is found that, in any model in which the shoes of the VI wells have no direct communication pathway with the highest permeabilities and porosities zones of the reservoirs, the high temperature zones occur in two chambers, otherwise, there is one high temperature zone.(ii) It is found that generally, the combustion front tends to be lopsided in favour of the most permeable and porous zone. In the case of a bottom-up progressive increase in permeabilities and porosities (model L1), the single combustion front has greatest advance horizontally at the top and axially in the middle of the reservoir, while in model L2 (the converse of model L1), the combustion fronts propagated in two chambers before the chambers overlapped in the toe region of the HP well where it advanced fastest. Therefore, the combustion zone in model L1 was far more stable than in model L2.(iii) It is found that the combustion fronts in model L3, with the lowest permeabilities and porosities at the centre in the longitudinal direction, propagated in two chambers that overlapped each other around the toe region of the HP well and advanced greatest in the HP well and on either lateral edge of the reservoir. In model L4, which has lateral gradation in permeabilities and porosities, however, the thinner edge of the wedge-shape combustion front had advanced fastest along the vertical mid-plane where the HP well was located. Thus, the combustion zone in model L3 was far more stable than that in model L4.(iv) It is found that in all the models except model L4, there exist rich oil saturation zones in the most permeable and porous regions located ahead of the mobile oil zone (MOZ) of each reservoir. These are formed due to restrictions in the pathways via which the mobilised oil can drain into the HP well. In model L4, the HP well is already in the most permeable zone and consequently, the fluids that favourably reach there are rapidly gravity-drained into the HP well.

An analysis of the development path of ethnic villages under the protection of traditional Jiarong culture

Most of the villages in the north-west ethnic areas of Sichuan are located within a culturally rich zone. However, during the process of village modernization, the protection and inheritance of traditional culture are often overlooked. This study has investigated the construction techniques and spatial components of traditional villages in Lixian, Sichuan Province, from the perspective of cultural inheritance. It analyzes and synthesizes representative design language and proposes a design concept that combines spatial perspective and cultural inheritance to conduct research on design paths aimed at strengthening functional positioning, optimizing spatial layout, improving village style, and improving infrastructure. The objective is to establish a research path to maintain the village-style during post-disaster process reconstruction and village development, thus protecting the unique local architectural culture and achieving comprehensive village development. In addition, we explored issues such as the lack of architectural style and the lagging development of human settlements, aiming to promote rural revitalization and integrated urban-rural development in this area.

Laminar flame speed measurement and combustion mechanism optimization for ethylene–air mixtures

AbstractEthylene plays a crucial role as an intermediate component in the cracking and combustion processes of large molecular alkane and olefins. In this article, the laminar flame speed of ethylene–air mixtures was measured using the heat flux method. The mechanism of ethylene was simplified by utilizing the error propagation directed relationship graph (DRGEP) and sensitivity analysis (SA), and the Arrhenius pre‐exponential factors for 20 selected reactions in the skeletal mechanism were optimized using the particle swarm optimization (PSO) algorithm. Finally, an ethylene optimization mechanism including 39 species and 85 reactions was obtained. The prediction results for flame speed, ignition delay time, and species concentration were compared with experimental data and other mechanisms, covering a wide range of temperatures (298–1725 K), pressures (1–22.8 atm), and equivalence ratios (0.5–2.0). The findings demonstrate that the optimization mechanism not only improves the prediction results of laminar flame speed in the rich combustion zone and low oxygen environment but also enhances the prediction accuracy of the ignition delay time at high pressure and in the lean combustion zone, as well as the prediction accuracy of C2H4 and H2O radicals. In conclusion, the optimized mechanism exhibits higher accuracy and broader applicability.

The North Equatorial Current and rapid intensification of super typhoons

Super Typhoon Mangkhut, which traversed the North Equatorial Current (NEC; 8–17 °N) in the western North Pacific in 2018, was the most intense Category-5 tropical cyclone (TC) with the longest duration in history—3.5 days. Here we show that the combination of two factors—high ocean heat content (OHC) and increased stratification — makes the NEC region the most favored area for a rapid intensification (RI) of super typhoons, instead of the Eddy Rich Zone (17–25 °N), which was considered the most relevant for RI occurrence. The high OHC results from a northward deepening thermocline in geostrophic balance with the westward-flowing NEC. The stratification is derived from precipitation associated with the Inter-Tropical Convergence Zone in the summer peak typhoon season. These factors, which are increasingly significant over the past four decades, impede the TC-induced sea surface cooling, thus enhancing RI of TCs and simultaneously maintaining super typhoons over the NEC region.

Large eddy simulation of combustion characteristics during dual fuel switching process in gas turbine combustor

The present study aims to investigate the combustion characteristics, fuel switching strategy, and flame stability associated with fuel switching processes in a dual-fuel gas turbine combustor. Specifically, the Large Eddy Simulation method is employed in conjunction with a skeletal chemical reaction mechanism to simulate the fuel switching process. It is revealed that the presence of a local rich combustion zone, formed by an increased accumulation of fuel in the head region, leads to the displacement of the heat release position towards the downstream inner shear layer. Additionally, this condition causes a reduction in the recirculation zone area and a deterioration in the uniformity of fuel blending. Simultaneously, the combustor experiences low-frequency, high-amplitude pressure pulsations, as well as pulsations in the heat release rate. Furthermore, a comparative analysis is conducted to assess the discrepancies among three distinct fuel supply strategies employed during fuel switching. The fast-opening strategy is found to demonstrate superior performance indicators, as it accomplishes filling the combustor performance indicators within 80% of the allocated time due to its lower initial fuel changing rate.

Microstructure and mechanical properties of SiCp/CF/Al hybrid composites with heterostructure constructed by macroscopic “core-shell” structure

Designing heterostructure is an effective way to comprehensively improve the strength-ductility of composites. However, the current methods of heterostructure integration consumes a large amount of energy. In this study, a macroscopic “core-shell” structure is designed with low cost and low energy consumption. The SiC particles (SiCp) and carbon fiber (CF) reinforced aluminum-based hybrid composite (SiCp/CF/Al) with heterostructure was fabricated utilizing the spark plasma sintering (SPS) method. The microstructure, interfacial structure, and mechanical properties of the SiCp/CF/Al before and after hot rolling were comprehensively investigated. The results revealed that the Vickers hardness values of the rich particle zone with high SiCp content were 54.32% and 48.10% higher than those of the poor particle zone before and after hot rolling, respectively. The synergistic strengthening effect of SiCp and CF significantly enhanced the yield strength and plasticity of the SiCp/CF/Al. Before and after hot rolling, the yield strength of SiCp/CF/Al was 242.68% and 173.16% of single CF-reinforced Al matrix composites, respectively. The extrinsic toughening was achieved through crack passivation and deflection at the interface of the rich particle zone and poor particle zone. Furthermore, the hindering and storing effects of the SiCp and CF on dislocations represented the primary intrinsic toughening mechanisms.

A review on gas permeability of polymer matrix composites for cryogenic applications

Fiber-reinforced polymer matrix composites are increasingly considered for lightweight cryogenic pressure vessels due to their excellent combination of tailorability, specific mechanical properties, and relatively low coefficients of thermal expansion. However, significant challenges must be overcome to fully utilize PMCs for cryogenic fuel tanks in terms of transverse microcracking and subsequent permeation of cryogenic fuel. Gas permeation and microcrack densities of cryogenically cycled composites are highly influenced by their layup, ply thickness, load case, and manufacturing defects like voids and resin rich zones. There has been a significant amount of research on measuring gas permeation of composites fatigued under pure thermal or uniaxial thermo-mechanical stresses. However, results demonstrate that the gas permeability should be measured under biaxial thermo-mechanical stresses to properly gauge the leakage characteristics of damaged composites. This paper summarizes the results from over a hundred papers on the key parameters that influence the gas permeability of composites, appropriate testing methods to cycle composites for permeability measurement, methods to limit the evolution of transverse microcracks, and materials traditionally used for the fabrication of all-composite cryogenic fuel tanks. Thin plies and nanofiller-toughening of the matrix have been shown to provide significant improvements in transverse microcrack suppression within cryogenically cycled composites.

Enhancing strength and ductility of Al-matrix composite via a dual-heterostructure strategy

Aluminum matrix composites (AMCs) often have low ductility, which has been a long-lasting issue in the last few decades. This problem arises largely from the non-deformability of reinforcement particles, which leads to premature failure of the matrix-particle interfaces. Here we propose a new microstructural design strategy for AMCs: distribute the reinforcement particles non-uniformly to form dual-heterostructured AMCs. The zones with high-density particles are recognized as the hard zones, which carry less plastic strain than the particle-free zones to prevent premature interfacial failure. A dual-heterostructured Al-matrix nanocomposite is fabricated, in which AlN nanoparticles are distributed in a dual-level hierarchy: first level heterogeneous nanoparticle distribution and second level heterogeneous zones with different grain sizes. The dual heterostructure produced a unique dual level hetero-deformation induced (HDI) strengthening and hardening to produce high strength and ductility. The dual level HDI strengthening effect has been revealed by the inflection points on the loading-unloading-reloading stress-strain curves. Furthermore, the evolution of local strain fields during the in-situ tensile deformation directly proved the occurrence of strain partitioning, in which the ductile particle free zones have carried a larger strain than the hard particle rich zones. Dispersive shear strain bands are observed for the first time in AMCs. These findings are expected to help design other metal matrix composites with superior mechanical properties.

The Effect of Cooling Rate on the Banded Structure of 20CrMnTi Gear Steel Based on C Diffusion and Partitioning Analysis

This study, through experimental analysis and numerical calculations, not only identifies the critical cooling rate for eliminating banded structures in 20CrMnTi gear steel but also analyzes the impact of cooling rate on banded structures, including the mechanisms related to element distribution and interface migration. The results indicate that the fundamental cause of banded structure formation is the presence of chemical segregation bands, and increasing the cooling rate leads to a reduction in the grade of ferrite/pearlite banded structures, with a critical cooling rate of 0.55 °C s−1. Bainite and martensite banded structures are observed in samples cooled at rates of 3 and 5.8 °C s−1, respectively. As the cooling rate increases from 0.07 to 1 °C s−1. The ferrite phase transformation time in the solute‐poor zone is shortened from 171 to 12 s within the ferrite phase transformation temperature difference (Δ) between the poor and rich solute zones. The concentration difference of carbon (C) on both sides of the α/γ phase interface increases from 0.350 mass% to 0.431 mass%, and the diffusion distance of C decreases from 34.38 to 7.57 μm. When the diffusion distance of C is less than half of the width of the solute‐rich banding (12.5 μm), the ferrite banded structure disappears.

Dynamics and determinants of human–hyaena conflicts in the surroundings of a protected area

AbstractHuman–wildlife conflicts (HWC) predominate in areas proximal to wildlife rich protected zones. Whereas herbivore driven HWC is easy to detect, the stealth, nocturnal and predacious nature of carnivores leads to human injury and fatality, livestock depredation and loss of livelihoods in communities proximal to Sengwa Wildlife Research Area (SWRA) in northwest Zimbabwe. This study aimed to: (1) determine the nature of human–hyaena conflicts (HHCs), (2) explore the drivers of HHCs and (3) investigate the spatial and temporal movement patterns of hyaenas in HHC hotspots in areas proximal to SWRA. The results indicated that prevalent HHC types include livestock depredation, property damage, harassment, nuisance and disruption of human movements around SWRA. Locals indicated removal of park fences, human settlement on wildlife migration corridors, increases in hyaena populations, easy stray livestock targets, increased poaching and removal of natural wildlife death carcasses by illegal hunters as key drivers of HHC. Hyaenas have a predetermined non‐seasonal movement pattern following traditional wildlife migration corridors through SWRA into proximal communities. Human–hyaena conflict abatement strategies should be underpinned by indigenous local knowledge of hyaena movement and hunting patterns. Integrating citizen science data and remote sensing techniques aids to track and understand movement and hunting patterns of hyaenas inside and outside of protected areas.

Novel oxadiazole-thiadiazole derivatives: synthesis, biological evaluation, and in silico studies

In the search for new anticancer agents, we synthesized a new series of thiazole derivatives carried on thiadiazole-oxadiazole hybrid. Final compounds (5a–5i) were analyzed via 1H NMR, 13C NMR, and HRMS. The pharmacokinetic profile of the targeted compounds was predicted via in silico calculations. Their anticancer properties were determined using MTT method against MCF7 and A549 cell lines. Compounds 5a, 5b and 5c were found more active against MCF7 cells than A549 cells while they were not cytotoxic on L929 healthy cells. Generally, it can be summarized that acetamide moiety has a pivotal role in anticancer activity. For further studies, their aromatase inhibitory activity was evaluated. After determination all these features, the binding modes of the active compounds and the stability and relation of the ligand-enzyme complex were investigated using molecular docking and molecular dynamics simulation studies, respectively. In vitro and in silico studies suggest two important structure-activity relationship (SAR) points that at least one azole ring is essential, and if there is approximately 8.0 ± 0.5 Å distance between the H-bond rich zone of ligand and the heteroaryl ring system of ligand has a major impact on aromatase inhibitory activity. Compounds with small group substitution on thiazole are found potentially may be used for the treatment of anti-breast cancer orally. Communicated by Ramaswamy H. Sarma

Enhancing mechanical properties of Al matrix composites via porous reduced graphene oxide strengthened interface

Defective graphene can effectively improve the interface between graphene and Al matrix. To further improve the interface bonding between graphene reinforcement and Al matrix, chemical etching was proposed to generate nanopore defects on surface of graphene oxide (GO), forming porous reduced graphene oxide (P-RGO) reinforcement. P-RGO/Al hierarchical composites were prepared by electrostatic adsorption, ball milling, and spark plasma sintering. "P-RGO rich zones" were formed via uniformly distributing P-RGO into Al matrix, and thus a hierarchical structure consisting of "P-RGO rich zones" and "P-RGO free zones" was constructed. The results show that ultimate tensile strength (UTS, 339.8 MPa), yield strength (YS, 296.1 MPa), and elongation (εf, 9.1 %) of P-RGO/Al hierarchical composites were 23.1 %, 78.1 %, and 9.6 % higher than those of GO/Al composites. Nanopore defects increased specific surface area of P-RGO and provided nucleation sites for the interfacial reaction. Al2O3 formed in situ at the nanopores and Al12Mg17 precipitated at the interface together improved the interfacial bonding and enhanced the load transfer. The hierarchical configuration established by "P-RGO rich zones" and "P-RGO free zones" arranged alternately in space promotes crack deflection and increases crack propagation path. This work provides a promising way for the fabrication of high-performance composites.

Interrogating the notion of giving voice: designing for polyphony in game-based learning ecologies

ABSTRACT This paper illuminates how a young person and adults learned to design for robust learning in the context of video-game play. We argue that consequential learning can emerge through the intentional design of learning spaces where normative conceptions of novice and expert are re-imagined. Our analyses revealed that everyday digital game play was a rich zone of learning, fostering principled polyphony: the orchestration and symphonic arrangement of multiple voices and tools. Drawing on a cultural historical approach, we show how young people and adults create new social futures, through robust collaboration and the creation of syncretic sociotechnical arrangements.

Effect of Mo on high entropy Ti-Nb-Zr-Ta alloy: Phase equilibria, microstructure and mechanical properties

Thermal and mechanical properties of Ti-Nb-Ta-Zr high entropy alloys are often influenced by element content and manufacturing routes, producing significant differences between mechanical properties and microstructure. This work presents a Ti-Nb-Ta-Zr alloy in which Mo is added by adjusting the composition with phase equilibria simulation, improving the mechanical properties based on a mixture of two chemically different solid solutions (BCC1 and BCC2). The materials were produced by arc-melting suction casting. Characterization of the dendritic and interdendritic zones was carried out by means of X-ray spectroscopy, indicating the segregation of Ta and Nb in BCC1 and Zr and Ti in BCC2 phases. The dislocation density increased preferentially in the interdendritic Zr-Ti rich zones. The mechanical properties results were related to the chemical differences between the BCC1 and BCC2 lattice parameters induced by the Mo addition. With Mo segregating between both BCC cells, the resulting microstructure increased the yield strength, being confirmed with the kernel average maps, which showed that, after compression tests, the interdendritic zone accumulated a high density of dislocations, resulting in the segregation of Ti and Zr, affecting the mechanical response of Mo containing alloy.

Evolution of an ancient VMS ore-forming system recorded by pyrite and sphalerite mineral texture, trace elements, and sulfur isotope: A case study from the Huangtupo Cu-Zn (-Au) deposit, Eastern Tianshan, NW China

The Huangtupo Cu-Zn (-Au) volcanogenic massive sulfide deposit is hosted in a suite of Early Paleozoic basic to acidic volcanic, volcaniclastic rocks in the Eastern Tianshan orogen, northwest China. The Cu-Zn orebodies are characterized by the zoning of metallogenic elements upward from a deep stockwork mineralized zone (Cu > Zn) to a shallow massive mineralized zone (Zn > Cu). Detailed petrographic and LA-ICP-MS analyses have identified five types of pyrite and three types of sphalerite. These sulfides can be distinguished in a paragenesis with four stages of sulfide mineralization. The preore stage (SⅠ) from the deep volcanic rock contains subhedral-euhedral pyrite (Py1) with high trace element contents (e.g., Co, Ni, and Ti; Average value of total trace elements: 16764 ppm), except for Sb, and Tl, indicating a euxinic and high-temperature environment. Both the disseminated and veined pyrite (Py2) from the early ore stage (SⅡ; stockwork zone) and the euhedral pyrite (Py3) from the main ore stage-1 (SIII-1) have a similar chemical signature, suggesting that they precipitated under similar physicochemical conditions. These two paragentic stages of pyrite contributed only minimally to the trace elements endowment, except for higher Se contents. The continuous convection of hydrothermal fluids caused a large accumulation of copper and zinc, forming massive orebodies. Pyrite within the Zn(Cu)-rich zone of the main ore stage-2 (SIII-2) comprises three sub-generations (Py4a ∼ c) which are characterized by enrichment in most trace elements such as Au, As, Cu, and Sb. Pyrite 4a ∼ c formed in a fluctuating sedimentary environment and recorded the injection of a short-term, gold-rich fluid, which dissolved and reprecipitated trace elements from earlier ores and surrounding rocks. Orebody deformation and local metamorphism played a key role in this gold enrichment event. Pyrite (Py5) from the late ore stage (SⅣ) is deficient in most elements but relatively enriched in Co, Ni, and Se. Three stages of sphalerite associated with the Py3 ∼ 4 have been distinguished in the SIII. From Sp1 to Sp3, the content of Fe, Ge, Mo, and Cd decreased gradually, but the Sp2 is relatively depleted in Ag, As, Au, Pb, and Sb compared to Sp1 and Sp3. The sensitive variation of As, Co, Ni, Se, Pb in pyrite and Fe, Cu, Mn, Sb, Cd in sphalerite provide significant information for reconstructing the hydrothermal evolution process. The sulfur isotopes of these pyrites determined by in situ LA-multicollector (MC)-ICP-MS analyses are concentrated around 0‰, but vary significantly from −2.3 to 5.8‰. The δ34S values of the sphalerite range from −3.5 to 4.0 ‰ and tends to decrease from Sp1 to Sp3. These results show that the metals of the SIII were most likely derived from the deep-seated Early Paleozoic subvolcanic intrusion and Daliugou Formation during the evolution of regional island arcs.Combining the chemical, and isotopic data and geological features, the ore-forming process of an ancient VMS deposit was deduced. These results constrain the texture, composition and sulfur isotopic signatures of sulfides in veins and deformed ore bodies, as well as the gold enrichment mechanism, and also reflect the vertical variation of trace elements at the scale of VMS deposits, supporting the existence of multiple depositional mechanisms.

Site suitability analysis for Ecotourism potential using Analytical Hierarchy Process (AHP) and GIS in Chamoli district, Uttarakhand

With the ever-increasing need to manage and conserve the ecosystem, as well as the growing business potential for tourism, it is becoming increasingly important to address and align these two domains. Ecotourism enters the scene to provide a solution for anthropogenic interruptions at ecological tourist sites, with its potential to provide sustainable maintenance and development of both the environment and the local communities closely related with natural ecosystems. Tourism is one of the most valuable industries in India and the world, accounting for a considerable portion of most countries' economies. Chamoli is one of the tourist hotspots districts in India. Along with being an ecologically rich zone residing in the Himalayas, it possesses some of the highest peaks and national parks like Nanda Devi and valley of flowers. The study area is also prone to various natural disasters like floods, earthquakes, landslides, and the recent one being the rishi-ganga landslide of February 2021. The use of GIS tools in conjunction with AHP allows for a more streamlined and holistic approach to making scientifically calculated conclusions. We attempted to establish the prospective zones of ecotourism sites in our study region by considering a variety of factors that influence those sites of sustainable zones, such as slope, topographic roughness, elevation, road closeness, river proximity, and proximity to a protected area. The study area's data and information were geospatially analysed to build an ecotourism potential map that can be used as a guide for planning sustainable resource management and development operations in the Chamoli district.
 Keywords: - Ecotourism (ET), Analytical Hierarchy Process (AHP), Site-Suitability, Chamoli.

A CFD Study on the Effects of Injection Timing and Spray Inclusion Angle on Performance and Emission Characteristics of a DI Diesel Engine Operating in Diffusion-Controlled and PCCI Modes of Combustion

In three-dimensional (3D) computational fluid dynamics (CFD) simulations, the effects of injection timing and spray inclusion angle (SIA) on performance and emissions of diffusion-controlled and Premixed Charge Compression Ignition (PCCI) combustion in part load for a heavy-duty direct injection (HDDI) diesel engine are studied. The start of injection (SOI) of a 146° SIA injector is varied between −70 and −10 °crank angle (°CA) after top dead center (ATDC). For −50 °CA ATDC SOI with various SIAs between 80° and 146°, PCCI combustion reduces mono-nitrogen oxide (NOx) emissions significantly compared to conventional diesel combustion (CDC). Due to incomplete combustion in rich zones formed by droplet–cylinder wall interaction, early wide SIA injection deteriorates combustion efficiency (CE) and Indicated Mean Effective Pressure (IMEP) and increases soot and carbon monoxide (CO) emissions. Narrow-angle sprays interacting with the piston bowl elevate CE and IMEP and decrease soot and CO emissions but increases NOx emissions. Optimal combustion is achieved by avoiding fuel droplet–cylinder wall interaction. By spray-targeting at the stepped lip of the piston bowl, 100° SIA and −50 °CA ATDC SOI yield, respectively, the highest CE and IMEP: 97.8% and 3.37 bar and the lowest soot and CO emissions: 33.5 and 2.2 ppm, with acceptable NOx emissions.