Set Of Bars Research Articles

Experimental investigation on the compressive behaviour of foam concrete light steel keel composite wall

ABSTRACT This study aims to explore a new load-bearing structure of foam concrete-light steel keel (FCLS) composite wall. Compared with the traditional beam-column frame structure, this structure has the characteristics of lightweight, thermal insulation, sound insulation, fire resistance, etc. and has better Carrying capacity. The compression performance of 10 FCLS composite walls was studied in depth by conducting axial and eccentric compression tests. The effect of the spacing of foam concrete, middle horizontal steel and self-tapping screws on the compressive bearing capacity of the middle column of FCLS composite wall under compressive load was investigated. The results showed that the bearing capacity of the composite wall filled with foam concrete increased by 70%-80%, while reducing the spacing of self-tapping screws could increase the bearing capacity by 5%-6%. In addition, the tie bar settings have little impact on the bearing capacity. Based on these influencing factors and through the analysis of test data, the calculation formula for the bearing capacity of the composite wall was obtained, and the effectiveness of the method was verified.

Flexible, lightweight, tunable robotic arms enabled by X-tensegrity inspired structures

Robotic arms have remarkable applications in diverse fields such as medical rehabilitation, disaster relief, and space exploration. Enhancing their rigidity, load-bearing capacity, and motion simplicity is key to broadening their usage. Utilizing the admirable flexibility and strength of tensegrity structures, made of rigid bars and elastic strings, we introduce a new type of flexible robotic arm. This arm is constructed using a sequence of two-dimensional X-tensegrity inspired modules. Each module comprises two sets of triangular bars linked by three strings, enhancing the arm’s ability to deform and resist impact forces. The joints between modules are stiff, allowing for angular adjustments to create three-dimensional configurations with adjustable stiffness and curvature. Through theoretical analysis, simulations, and experiments, we have shown that this tensegrity-based robotic arm exhibits superior stability, flexibility, and scalability.

Spit bar deposits from the Upper Cretaceous (Cenomanian) transgressive sequence in NE Bohemia (Czechia)

We propose a spit bar setting as the possible palaeoenvironment of the basal Late Cretaceous transgressive sequence in NW Bohemia. A new Cenomanian transgression model for the Bohemian Basin is also proposed. The uppermost Devět Křížů Sandstone, which has been conventionally referred to the Bohdašín Formation, probably represents the middle or lower upper Cenomanian (Upper Cretaceous), not the Triassic as previously supposed. We assume that this controversial unit was deposited before the main latest Cenomanian–early Turonian transgression. The spit bars were likely overgrown by vascular plants during their emergence in the late Cenomanian, and then inundated during the latest Cenomanian and early Turonian transgressive phases. The studied deposits had been intensively bioturbated, and the cf. Taenidium suite was recognized for the first time in them alongside the Thalassinoides assemblage (T. paradoxicus, T. suevicus, Thalassinoides isp., cf. Thalassinoides), which are characteristic of the Scoyenia and Glossifungites ichnofacies, respectively. The bioturbated, rhizolith-bearing horizon was presumably a paleosol.

A typical point bar with atypical strata in the McMurray Formation, Alberta, Canada: Floods, tides and high suspended sediment concentrations

AbstractStratigraphic positions and the nature of some breccias and mudstones observed in the Lower Cretaceous McMurray Formation type section (Alberta, Canada) challenge the existing fluvial point bar facies models. The currently applied large‐scale, tidally influenced, sandy bedload facies model suggests that point bars fine upward, where breccias and cross‐strata occur at the base of the succession and mud content increases upward. Instead, this study documents that: (i) mudstone clast breccias are not exclusively associated with basal channel‐lag deposits and can occur throughout the point bar; and (ii) stratified mudstones are not limited to the top of the fining‐upward succession and can occur at or near the channel base. This outcrop data, including lithology, sedimentary structures, trace fossils, bed thickness and boundaries, and the nature of stratal packages, further suggests dynamic interplay between fluvial and tidal processes. This article discusses the potential role of high‐magnitude river floods in temporarily elevated suspended sediment concentrations and highlights that fluid mud processes played a crucial role in mud deposition in both tide‐influenced and fluvial parts of the system. Fluid mud processes allowed mud deposition along the channel base and across the point bar accretion surfaces. The breccias predominantly consist of broken pieces of inclined heterolithic strata and mostly occur on accretion sets of point bars, suggesting erosion and collapse of the point bar rather than of the cutbank. This work introduces a novel perspective to the existing models of point bar sedimentation, offering a new end member and concepts for the interpretation of subsurface data. The authors hope that this research encourages further investigations into similar phenomena elsewhere in the world.

An Analysis of the Obligations of COMESA Public Procurement Regulations: The Case of Zimbabwe’s Public Procurement Regulatory Framework

With the coming into force of the new Constitution in 2013, public procurement was given a constitutional status in Zimbabwe. The Constitution sets out vital principles that public procurement legislation must comply with. Moreover, it is a requirement of the Constitution that the governance of Zimbabwe must be pursued in accordance with Zimbabwe’s international law obligations. Zimbabwe is a founding member of the Common Market for Eastern and Southern Africa (COMESA). To accelerate interstate trade, COMESA promulgated Public Procurement Regulations (PPR) for regional competitive bidding across member states. The viability of the regional trade agreements is hinged on mutual cooperation. Pursuant to the foregoing, member states are required to domesticate international agreements into their municipal laws. In 2017, the Zimbabwean legislature passed the Public Procurement and Disposal of Public Assets Act 5 to give effect to the provisions of section 315(1) of the Constitution (Amendment No. 20), 2013. The public procurement reform agenda in Zimbabwe occurred close to a decade after the adoption of the public procurement regulations by COMESA in 2009. This article explores the obligations imposed on Zimbabwe pursuant to the public procurement regulations. This is done by identifying the public procurement principles enumerated in public procurement regulations, which are binding on member states. This article endeavours to answer the question: To what extent does the Zimbabwean legal framework conform to public procurement regulations? This article notes that the legal framework underlying public procurement in Zimbabwe, by and large, conforms to the bar set in the public procurement regulations. Nonetheless, it highlights Zimbabwe’s public procurement shortcomings. The article concludes by making possible legislative recommendations.

How do disadvantaged groups perceive allies? Women's perceptions of men who confront sexism in an egalitarian or paternalistic way

AbstractIn this research, we focused on women's perception of men as allies depending on the type of confrontation. We conducted four experimental scenario studies (Study 1 and 2 in a bar setting; Study 3 and 4 in a workplace setting) where a man confronted a sexist comment using either an egalitarian or paternalistic argument. Results showed that women are more likely to perceive egalitarian (vs. paternalistic) confronters as allies (Studies 1–4). This is explained by the fact that they contribute to reducing power asymmetries (decreasing perceived interpersonal power differences: Studies 2 and 4; or increasing women's empowerment: Studies 3 and 4). Furthermore, the egalitarian (vs. paternalistic) confrontation positively impacts interpersonal and intergroup relations, and this is explained by the perception of the confronter as an ally (Studies 1, 2 and 4). We discuss the role of disadvantaged group members’ perception of advantaged group members to disentangle the complexity of alliances.

Fluid suppression in amide proton transfer-weighted (APTw) CEST imaging: New theoretical insights and clinical benefits.

Amide proton transfer-weighted (APTw) MRI at 3T provides a unique contrast for brain tumor imaging. However, APTw imaging suffers from hyperintensities in liquid compartments such as cystic or necrotic structures and provides a distorted APTw signal intensity. Recently, it has been shown that heuristically motivated fluid suppression can remove such artifacts and significantly improve the readability of APTw imaging. In this work, we show that the fluid suppression can actually be understood by the known concept of spillover dilution, which itself can be derived from the Bloch-McConnell equations in comparison to the heuristic approach. Therefore, we derive a novel post-processing formula that efficiently removes fluid artifact, and explains previous approaches. We demonstrate the utility of this APTw assessment in silico, in vitro, and in vivo in brain tumor patients acquired at MR scanners from different vendors. Our results show a reduction of the CEST signals from fluid environments while keeping the APTw-CEST signal intensity almost unchanged for semi-solid tissue structures such as the contralateral normal appearing white matter. This further allows us to use the same color bar settings as for conventional APTw imaging. Fluid suppression has considerable value in improving the readability of APTw maps in the neuro-oncological field. In this work, we derive a novel post-processing formula from the underlying Bloch-McConnell equations that efficiently removes fluid artifact, and explains previous approaches which justify the derivation of this metric from a theoretical point of view, to reassure the scientific and medical field about its use.

How the bundengan string material affects its musical sound

Bundengan is a traditional musical instrument from Wonosobo Regency, Central Java, Indonesia. Bundengan consists of several main components, namely the kowangan resonator, a set of loaded strings, and a set of bamboo bars. Bundengan can imitate the sound of the percussive elements in gamelan lengger Wonosobo, such as gong, kempul, kenong and kethuk. This research aims to analyze the impact of the choice of bundengan string material on the frequency spectrum and temporal dynamics of the sound produced by the bundengan. Quantitative data is obtained by measuring the acoustical signal produced by each bundle string that is tested. Our data indicates that the natural gut badminton string is the most suitable string for the sound of gong, kempul and kethuk, with errors of 1.87 cents, 23.88 cents, and 0.88 cents, for the sound of gong, kempul, and kethuk, respectively. Meanwhile, the solid core badminton string with single wrap is the most suitable string for kenong, with an error of 3.29 cents. The data also shows that the natural string gut has the most suitable damping factor to produce the sound of the gong, with a damping factor of 0.036.

Coarse-grained submarine channels: from confined to unconfined flows in the Colombian Caribbean (late Eocene)

Submarine channel mouth settings are hardly preserved in the stratigraphic record. Although they are still poorly known with respect to other segments of turbidite systems, conceptual models are being refined in the light of new discoveries in modern and ancient examples. Still, some questions such as the transition between expansion zones and the traditional Channel-Lobe Transition Zone (CLTZ) remains open in ancient systems. Upper Eocene deposits of the Colombian Caribbean (San Jacinto Fold Belt) are interpreted here as a fan-delta-fed, submarine, coarse-grained channel-lobe system. It displays a well-preserved channel inception stage in the shelf break represented by sigmoidal to lens-shaped gravels, and planar cross-stratified pebbly sandstones (foreset and backset) interpreted as cyclic steps in an expansion zone. In a later stage, a classical channel-levee complex was developed, represented by channel fill elements showing sharp- and erosional-based, fining-upward sequences that are meters thick, having basal massive matrix-supported pebble conglomerates (hard—extrabasinal—clasts, rip-up clasts, coastal bioclasts), vertically evolving to liquefied massive to planar-laminated coarse-grained sandstones with phytodetrital carbonaceous laminae. They are interpreted as concentrated flow deposits (high-density turbidites) coming from continental areas or from coastal systems (i.e., delta reworking). Undifferentiated channel belt thin-bedded turbidites associated with levees and terraces deposits are related to these confined systems. The channel-lobe transition zone is characterized by debrites from cohesionless debris flow in a channel-mouth bar setting, representing bypass processes that developed distally into low-angle, planar cross- and sigmoidally-stratified (upstream antidune) pebble-size to coarse-grained sandstones that fill low-angle scours (cut-and-fill structures) in an antidune field setting with supercritical conditions. When the currents lose channel confinement, the setting is characterized by changes from Froude supercritical to subcritical flow conditions in an inner lobe to lobe off-axis environment. Large seasonal fluctuations in precipitation favor high sediment concentrations, promoting the formation of volumetrically significant fan deltas and coarse-grained submarine channels with high erosive capacity; therefore, their record helps refine interpretations of depositional processes, providing criteria for recognizing areas of the turbiditic systems that are hardly preserved. The particular aggradational conditions for the preservation and stratigraphic characterization of the rare exhumed submarine channel mouth systems make it possible to decipher sediment dispersal patterns and thus connect the models proposed here, from supercritical systems to the traditional models of turbiditic systems.

Variable Ophiomorpha ichnofabric: Improving the understanding of mouth bar environments in fan-delta complex depositional settings from the Upper Cretaceous of NW South America

Fan-delta deposits, an important sedimentary component of fan-delta complexes, are scarcely described in the ancient record because it is very difficult to distinguish them from other types of coarse-grained deposits (e.g., alluvial, fluvial, or deep marine deposits). This obstacle is overcome when a well-record of physical/biogenic sedimentary structures or fossils unambiguously marks the influence of the receiving basin. However, this is usually not the case. Here, we present the Ophiomorpha ichnofabric record as a key proxy of marine influence within a generally fluvial-dominated system for improving the paleoenvironmental understanding and reconstructing animal-substrate interplay during the evolution of a fan-delta complex. The ichnological record, together with detailed sedimentological analysis, allows us to define three ichnofabric types, distributed in four levels. The stratigraphic distribution of these features points to distal alluvial environments towards the base, dominated by debris and sheet flows deposits and locally shallow braided channels; they evolve upward into well-developed braided fluvial system whose facies arrangement is related to channel fills, locally influenced by debris flows. Subsequently, a basinward migration of the sedimentary system is recorded through the occurrence of the first level with Ophiomorpha ichnofabric A, and then ichnofabrics A and B in levels 2 and 3, respectively, suggesting marine-influenced mouth bar settings. Toward the top, another steep basinward migration is evidenced by Ophiomorpha ichnofabric C in level 4, indicating wave-dominated processes in distal mouth bars environments. The record of marine-influenced and dominated levels may indicate relative sea-level fluctuations related to local or autogenic processes at the basin scale. Furthermore, the present study demonstrates the ability of Ophiomorpha tracemaker to colonize challenging sedimentary environments.

Numerical Analysis of Cracked Double-Beam Systems

Based on elasticity theory, this paper discusses the static analysis of a cracked double-beam system in the presence of a Winkler-type medium. It is further assumed that the double-beam system is constrained at both ends by elastically flexible springs with transverse and rotational stiffness. Using a variational formulation, the governing static equations are derived and solved using analytical and numerical approaches. In the first approach, closed-form solutions for the displacement functions are obtained based on the Euler–Bernoulli beam theory. In the second approach, the Cell Discretisation Method (CDM) is performed, whereby the two beams are reduced to a set of rigid bars connected by elastic constraints, in which the flexural stiffness of the bars is concentrated. The resulting stiffness matrix is easily deduced, and the governing equations of the static problem can be immediately solved. A comparative analysis is performed to verify the accuracy and validity of the proposed method. The study focuses on the effect of various parameters, including crack depth and position, boundary conditions, elastic medium and slenderness. The validity of the proposed analysis is confirmed by comparing the current results with those obtained from other approaches. In particular, the results obtained by closed-form solution and CDM are compared with the Finite Element Method (FEM). The accuracy of the results was assessed by making comparisons with results found in the literature and reported in the bibliography. It was shown that the proposed algorithm provides a simple and powerful tool for dealing with the static analysis of a double-beam system. Finally, some concluding remarks are made.

The event-based influence of incentivizing and physical contexts on daily alcohol initiation and consumption.

Young adults often decide to engage in heavy drinking. Learning more about the real-time factors that predict decisions to initiate a drinking episode and how much is consumed in any single drinking episode is necessary in developing our understanding of momentary alcohol use and discrete decisions surrounding alcohol use. The current study examined the association between contextual factors and decisions to initiate and consume alcohol in 104 young adult individuals over 2 weeks via mobile daily diary. Participants responded to daily notifications about decisions to drink or not and the contextual factors surrounding each event. The contextual factors included the situation (e.g., bar setting and pregaming) and incentives (e.g., alcohol, social, and mood enhancement). Multilevel analyses revealed that incentives predicted both the initiation of drinking and the amount consumed. Event-based alcohol and mood incentives predicted the initiation of drinking, while alcohol, mood, and social/party incentives predicted how much was consumed at a specific event. However, context had a more complex association with drinking outcomes. Being in a bar, alone, or at a residence predicted decisions to initiate drinking, while being in a bar, pregaming situation, or other party situation with others who are drinking predicted how much a person drank. The results highlight the importance of studying event-specific predictors of drinking decisions and the complex association between context/location and the type of drinking decision or outcome.

Dynamic tensile and compressive behaviour of AA7475-T7351 alloy under different strain rates and temperatures

The mechanical behaviour of the aluminium alloy AA7475-T7351 under different loading rates and temperatures is investigated in this article. The high strength AA7475-T7351 alloy under consideration, with its quasi-static tensile strength of 560 MPa at room temperature (25 °C), is stronger than most other aluminium alloys. At the beginning, the specimens are evaluated under quasi-static tension and compression along the rolling direction at five different temperatures (25 °C, 100 °C, 150 °C, 200 °C and 250 °C) on a universal testing machine. Thereafter, an extensive experimental study is conducted on the Split Hopkinson pressure bar set up (SHPB) and the tensile Hopkinson bar (SHTB) to study the constitutive behaviour of AA7475-T7351 specimens at higher strain rates (up to +3000 s−1 for tensile and −4400 s−1 for compression) and elevated temperatures. The strength and ductility of AA7475-T7351 are observed to depend on the loading direction (tension/compression), strain rate and temperature. The efficiencies of the two widely used constitutive models (Johnson-Cook and KHL) for predicting the mechanical behaviour of AA7475-T7351 are also examined.

Ichnoassemblages from the Wilcox Formation in the Burgos Basin, northeastern Mexico

Abstract An ichnological analysis of the Paleocene–Eocene Wilcox Formation at San José de la Laja and La Curva localities within the Burgos Basin in northeastern Mexico revealed seven ichnogenera: Chondrites , Diplocraterion , Ophiomorpha , Palaeophycus , Planolites , Sinusichnus and Skolithos . The trace fossils were grouped into different ichnoassemblages, including a detailed facies analysis. These results show their apparent association with the Skolithos and Cruziana Ichnofacies in the two studied localities. The integrative analysis of trace fossils and lithofacies made it possible to infer plausible depositional environments for registered periods of fair-weather conditions in both localities of the Burgos Basin, which represent ecosystems characterized by low diversity and abundance. In San José de La Laja, the environment varies from storm affected to tidal setting. In La Curva, lithofacies and ichnology are modulated by storm events in a transitional shoreface, coastal bar and intertidal setting within a deltaic plain. Both localities indicate a shelf impacted by deltaic processes and storm events. Living conditions for most endobenthic organisms were harsh. These results support a long-term regression of the coastal zone during the Paleogene–Neogene and suggest a palaeoenvironment similar to this in the south of Texas during the Paleogene.

The Information-Motivation-Behavioral Skills Model and Unprotected Sex: Assessing the Model's Utility and Predictability Among Bar Patrons in Tshwane, South Africa.

The Information-Motivation-Behavioral skills (IMB) model has been a useful tool for understanding sexual risk behavior. However, its utility in predicting sexual risk behaviors among bar patrons, for whom the bar setting poses a higher risk of alcohol-related sexual risk behavior, has been underexplored. We assessed (1) the extent to which the IMB predicted number of episodes of unprotected sex in the past six months and (2) whether incorporating sex under the influence of alcohol and alcohol use improved the predictability of the model among bar patrons. Hierarchical regression models were conducted on data from 406 men and women from bars in rural areas of North-West province, South Africa. Behavioral skills were the sole IMB variable to predict unprotected sex with main partners (β = - 0.40; p < .001), explaining 18% of the variance. Variance explained increased to 21% with addition of sex under the influence of alcohol (β = 0.13; p = .019) and further increased to 26% with the addition of alcohol use (β = 0.24; p < .001). Motivation (β = - 0.21; p = .006) and behavioral skills (β = - 0.21; p = .006) were the significant IMB predictors of unprotected sex with casual partners (explaining 15% of the variance). Variance explained increased to 22% with the addition of sex under the influence of alcohol (β = 0.26; p = .001), but alcohol consumption was not an independent predictor of episodes of unprotected sex with casual partners. Interventions for improving HIV prevention behaviors among bar patrons should focus on enhancing individuals' behavioral skills and motivation and reducing their alcohol consumption.

Development of Velocity Measurement Device and Calibration Using SHPB and Ballistic Impact Setup

A velocity measurement device was developed to measure the velocity of the striker bar of Split Hopkinson Pressure Bar (SHPB) set up. It measures the range of velocity magnitudes for different size of striker bars. The velocity measurement device measures velocity of the striker bar for varying pressure values. The readings were calibrated under freefall, SHPB and also using a ballistic impact testing setup present at the authors facility. The device was developed to produce consistent readings and these readings were tabulated.

Evolution of an aggradational wave-dominated delta: Sediment balance and animal-substrate dynamics (Upper Cretaceous La Anita Formation, Southern Patagonia)

Aggradational deltaic successions are uncommon in the stratigraphic record since deltas are progradational by nature. However, deltaic coastlines fed by multiple small distributaries rather than by a well-defined trunk fluvial distributary system might result in aggradational successions if the sediment is effectively redistributed from river mouths by active basinal processes (e.g., tides, fairweather waves, and/or storm waves). The wave-dominated deltaic succession in the lower part of the La Anita Formation accumulated during the foreland stage of the Austral-Magallanes Basin (Argentina). Through a sedimentological and ichnological study of the interval, we evaluate and discuss the potential controls on the evolution of aggradational wave-dominated deltaic successions.The studied stratigraphic interval is up to 150 m thick and includes facies deposited in wave-dominated prodelta, wave-dominated distal delta-front, wave-influenced mouth bar, terminal channel, and distributary channel settings. These facies associations stack vertically, forming clear thick aggradational sets. Fairweather wave processes largely dominate the delta-front and prodelta deposits, although discrete beds point to the periodic importance of linked storm-wave and river-flood processes. Owing to the alternation of beds generated during fairweather shoaling waves with those of coupled storm-wave and river-flood cycles, it is proposed that the overall aggradational stacking pattern of the delta is the response to the sediment balance. Clastic material supplied by the distributary channels of the delta was easily transported alongshore during fairweather conditions by longshore currents and basinward via storm-generated waves, and/or hyperpycnal currents and hypopycnal plumes generated by river floods.The alternation of these depositional processes strongly affected the benthic faunal communities, which is well expressed by the resulting ichnological suites. Storm-wave and river-flood events led to the widespread defaunation of tracemaking organisms, leading to generation of unburrowed beds. Between these events, short-lived colonization windows appeared locally, allowing sparse, facies-crossing dwelling and detritus-feeding burrows to be constructed by the recovering benthic communities. By contrast, during prolonged periods of fairweather shoaling, river-induced physico-chemical stresses were greatly reduced, and the resulting beds display elevated bioturbation intensities with greater numbers of burrows that record a wide range of behaviors.

Ichnology and Sedimentology of the Lower Cretaceous Wabiskaw Member (Clearwater Formation) Alberta, Canada

Identifying facies and paleoenvironmental interpretation of the rock record is complicated due to the interplay of independent variables (i.e. wave-, river- and tidal-input) in marginal- and shallow-marine environments. This study integrates sedimentology and ichnology to characterize the depositional environments of the Lower Cretaceous Wabiskaw Member. The deltaic and strand plain shoreface-offshore deposits of Wabiskaw Member of Clearwater Formation of northeast Alberta provide an excellent case study to evaluate the ichnological and sedimentological characteristics associated with laterally and vertically variable stresses in wave-influenced nearshore settings. The Wabiskaw Member is studied using four sedimentary facies associations (Ten sedimentary facies). Facies association 1(FA-1) consists of massive, sharp-based mudstones and lenticular sandstone with small-scale soft-sediment deformation features, syneresis cracks and small-scale oscillation ripples. The ichnological suite mainly includes small grazing and deposit-feeding traces, representing the Phycosiphon Ichnofacies. Facies association 1(FA-1) is interpreted to record deposition in a prodeltaic setting. Facies association 2 (FA-2) is fine-to-medium-grained sandstone and thin mudstone with current, oscillation and combined flow ripples. The low angle and trough cross-beds, soft-sediment deformation structure, mud chips and coal debris are common. The trace fossil suite includes sporadically distributed deposit-feeding traces belonging to the Rosselia Ichnofacies. This facies association is interpreted to be deposited in the delta front to a mouth bar setting. Facies association 3 (FA-3) is gray to bluish-gray mudstone with minor sandstone interbeds (massive, planar parallel to hummocky cross-stratified). FA-3 is moderate to highly bioturbated. The ichnodiversity and abundance is high with dominant horizontal and subordinate vertical traces, including the dominance of deposit and detritus feeding traces representing the archetypal Cruziana Ichnofacies ichnological suite. Facies association 3 (FA-3) is interpreted as being deposited in a storm-influenced offshore environment. Facies association 4 (FA-4) is upper fine to fine-grained glauconitic sandstone with minor mudstone interbeds at the base. Physical sedimentary structures including massive and planar (horizontal and low angle), hummocky, and swaley crossing-stratification. FA-4 is heavily burrowed with a diverse suite of horizontal and vertical traces of deposit and detritus-feeding structures, representing a proximal expression of Cruziana Ichnofacies. Facies association 4 (FA-4) represents distal lower to middle shoreface deposition. The Wabiskaw Member deltaic (prodelta-delta front) deposits, producing characteristic sedimentological-ichnological signatures, distinguishing these deposits from related strand plains. In addition to characteristic deltaic traits (e.g. soft-sediment deformation structures, fluid mud and syneresis cracks), these deposits commonly contain comparably stressed low-diversity and diminutive trace-fossil suites. On the other hand, fully marine strand plain shoreface-offshore complexes are characterized by comparably robust trace fossils with high ichno-diversity and bioturbation intensities.

Ti6Al4V-ELI Alloy Manufactured via Laser Powder-Bed Fusion and Heat-Treated below and above the β-Transus: Effects of Sample Thickness and Sandblasting Post-Process

Ti6Al4V-ELI is the most-used lightweight alloy in the aerospace industrial sector thanks to its high mechanical strength and corrosion resistance. The present paper aims, firstly, to evaluate the effects induced by different heat treatments, which were performed above and below the β-transus temperature on Ti6Al4V-ELI samples manufactured via Laser Powder-Bed Fusion in different orientations (XZ, XY, Z and 45°). The first set of tensile samples and bars were heat-treated at 1050 °C × 1 h, while the second and third set were heat-treated at 704 °C × 120′ following the AMS2801 standard specification, and at 740 °C × 130′. These heat treatments were chosen to improve the as-built mechanical properties according to the ASTM F3001 and also ASTM F2924-14 standard specifications. Optical and SEM measurements reveal primary, secondary and tertiary α-laths below the β-transus, while above this temperature, the microstructure varies in relation to the sample’s thickness. Secondly, this work analyzed the results obtained after a sandblasting process, which was performed on half of all the available heat-treated tensile samples, through XRD and Vickers microhardness measurements. XRD analysis also highlighted the presence of α2-Ti3Al and TiAl3 precipitates and the microstructural change in terms of the α-phase.

A Comprehensive Study on the Effect of Dimethyl Carbonate Oxygenate and EGR on Emission Reduction, Combustion Analysis, and Performance Enhancement of a CRDI Diesel Engine Using a Blend of Diesel and Prosopis juliflora Biodiesel

This paper examines the combined effects of ignition improvers (DMC) and EGR on the CRDI small single-cylinder diesel engine’s performance, combustion, and emissions. In this experimentation, 20% (B20) optimal mix of Prosopis juliflora oil biodiesel (PJOB) and 5 ml dimethyl carbonate (DMC) additive was used as test fuel. The fuel handling CRDI system factors such as injection pressure set at 600 bar and injection timing set to 21 (bTDC) with a compression ratio of 16 were considered for the study. For the EGR trial, 20% of the exhaust gas was recirculated under various BMEP circumstances. The test was performed with and without EGR and DMC additive conditions like (i) diesel @ 0% EGR, (ii) diesel + 5 ml DMC @ 20% EGR, (iii) B20 @ 0% EGR, and (iv) B20 + 5 ml DMC @ 20% EGR at the engine power output. The amalgamation of dimethyl carbonate (DMC) additives and EGR reduces NOx and smoke while increasing CO and HC emissions. In addition, the DMC additive and EGR improve thermal efficiency slightly. The overall clubbing of DMC additive and EGR rate indicates better performance for the selected factors than a CRDI engine with a six-hole conventional mechanical fuel injection system. The outcome of the work clearly demonstrates that both the 5 ml DMC additive and the 20% EGR rate of the B20 blend show optimum values of BTE, BSFC, and EGT of 32.93%, 0.27 kg/kw·hr, and 310.89°C, which is closer to diesel. Factors of combustion like cylinder peak pressure (CPP) and heat release rate (HRR) are 70.93 bar and 58.13 J/deg. The tailpipe exhaust of NOx and smoke is 1681 ppm and 31.30 (% vol), which is less than diesel. The HC and CO levels are 93 ppm and 0.38 (% vol), respectively, which are significantly higher than diesel fuel.