Scholars Junction - Mississippi State University Institutional Repository
Not a member yet
83664 research outputs found
Sort by
Interactive effects of drought and high night temperature on physiology and yield components of cowpea (Vigna unguiculata (L.) Walp.)
No full textCowpea is a nutrient-rich vegetable legume with significant potential to address protein-calorie malnutrition. However, exposure to drought stress (DS) and high night temperature (HNT) substantially threaten crop production, including cowpea. Several studies have examined the effects of DS, but there is limited information on the combined impact of DS and HNT during the reproductive growth stage of cowpeas. This study quantified the effects of individual DS or HNT and combination on physiological and yield-related traits. At the reproductive stage, three genetically diverse cowpea genotypes were subjected to four distinct growing conditions: (i) control (CNT, 24 °C night temperature, full irrigation), (ii) DS (24 °C night temperature, 40 % irrigation of CNT), (iii) HNT (28 °C night temperature, full irrigation), and (iv) DS + HNT (28 °C night temperature + 40 % irrigation of CNT). All treatments maintained a common daytime temperature of 32 °C. A 3.2 °C nighttime rise under DS reduced stomatal conductance (91.5 %), photosystem efficiency (17.4 %), resulting in lower pod weight (64.5 %), seeds per pod (14 %), and seed count (66 %). Individual stressors notably impacted seed number and yield, with DS resulting in reductions exceeding 30 %, followed by HNT at 23 % compared to CNT. Overall, seed yield decreased by 63 % and seed protein by 25.1 % under DS + HNT. Among genotypes, EpicSelect.4 showed greater tolerance to DS for physiology parameters, while UCR 369 performed better under HNT for yield. The stress impact on cowpea performance ranked as DS + HNT \u3e DS \u3e HNT, highlighting the need for further research to understand molecular mechanisms that cause different stress responses during reproductive and grain-filling phases
Manufacturing Legitimacy: Media Ownership and the Framing of the July 2024 Uprising in Bangladesh
No full textBangladesh witnessed its biggest nationwide mass uprising since gaining independence in 1971, which led to the overthrow of an authoritarian government that had existed for a decade. This study employed the protest paradigm to analyze how the protests were framed by mainstream print media and how media ownership influenced their coverage. Drawing on a quantitative content analysis of five major newspapers from different ownerships, the study explores dominant media frames, tone, and legitimacy of protest coverage. The findings indicate that media ownership significantly affects the credibility and tone of the protest coverage. The protest paradigm was applied more strictly by pro-government media outlets. Independent and anti-government outlets, on the other hand, took a more impartial stance. The study reveals how media ownership shaped the framing of dissent, reinforcing the protest paradigm in ways that aligned with the ruling party’s interests. This study adds to the body of knowledge on South Asian media bias and authoritarian information control
Effects of Liquid Properties on Pressure Loss in a Passive Rotation-based Phase Separator
No full textThe separation of liquid and vapor plays a crucial role in various engineering applications, especially in the use of cryogenic liquids for space exploration. The DynaSwirl® (DS) phase separator is a passive rotation-based phase separator, which provides an effective solution for achieving efficient separation in microgravity environments. The DS phase separator uses multiple elongated tangential injection inlets into the separation chamber, which enable stable operation and allow high tangential velocities and low pressure at the core of the generated vortex leading to effective phase separation. This research delves into the fundamental physics that governs the operation of these systems. A DS phase separator is analyzed through both numerical simulations and experimental methods. The DS phase separator employs centripetal and centrifugal forces generated within a swirl chamber to facilitate separation. The effectiveness of separation improves with increasing swirl strength; however, this enhancement leads to greater pressure losses throughout the system. This paper identifies and analyzes the various flow and liquid characteristics that influence pressure losses. These factors include the physical properties of the working liquid, such as density and viscosity, and the swirl strength, which is influenced by viscosity. Additionally, the study examines the impact of incorporating a vortex blocker/killer (BK) attachment on these losses. To conduct the investigation, we examine a set of six selected liquids of interest to NASA, which includes four cryogenic fluids: LN2, LH2, LOX, and LCH4, along with water and a water/glycerin mixture. Additionally, two sets of six fictitious liquids, whose properties are derived from these, are analyzed to isolate the effects of the liquid properties. The pressure losses primarily occur in three areas of the DS phase separator: 1) the inlet slots, 2) the exit orifice, and 3) the swirling flow within the chamber. For the BK configuration, the pressure loss caused by the swirl accounts for about 70 % of the total pressure loss from the wall to the exit when the Reynolds number exceeds 24,000, whereas without BK, this contribution is approximately 90 %. This highlights the effectiveness of the BK in reducing swirl-induced pressure losses. For a given flow rate, reducing viscosity is shown to decrease friction pressure losses but also to increase swirl pressure losses due to a strengthened vortex. In contrast, decreasing the flow rate and density results in reduced pressure losses across all three components of the system. This paper provides a comprehensive analysis of the flow and liquid characteristics, offering valuable insights for the design and optimization of devices that involve strong swirl flows
(En)Gendering Capacity: Neoliberalism, Empowerment, and Responsibility for Women in the UN’s Capacity Building Agenda
No full textThis article analyzes how the UN constructs capacity building as an element of its development agenda. It theorizes that the UN operates as a governmental actor, adopting and pursuing a political rationality of good governance, while also navigating structural limitations to its organizational authority in implementing this agenda imposed by the liberal international order. As such, this article argues capacity building emerges as a valuable technology of development for several reasons: firstly, it operates as an individual-level intervention, circumventing UN limitations on authority in mandating state action, and secondly, it is framed as demand-driven and empowering while delivering on the UN’s effort to improve the international system by promoting good governance. To explore this dynamic, this article undertakes an institutional ethnography of official UN texts to trace the thematic construction of the UN’s role amongst its dual mandate to promote empowerment and improvement. It finds that the UN constructs capacity building in accordance with neoliberal logics of efficiency and optimization, and in the process, specifically targets women as essential subjects who can most effectively deliver its good governance objectives. Thus, capacity building emerges as a uniquely gendered technology of development designed to promote neoliberal ideals of development as a way to confront structural failures of governance within the liberal international order, circumscribing women’s engagement in the development process as a result
Chantal Mouffe and Albena Azmanova, Forty years after Hegemony and Socialist Strategy (a conversation)
No full textEAF steel slag check dams and engineered biochar bioreactors as stormwater BMPs
No full textEutrophication from agricultural runoff is a growing concern, particularly in livestock dominated watersheds. This study evaluated the effectiveness of slag-and-biochar systems installed in gullies for reducing total suspended solids (TSS), total phosphorus (TP), and total nitrogen (TN) in stormwater runoff at the Mississippi Agricultural and Forestry Experiment Station (MAFES) dairy unit. Eighteen plots across six blocks were assigned one of three scenarios: control, slag-only, or slag-and-biochar. Runoff samples were collected upstream and downstream of each plot following 24 storm events between January 2023 and April 2024. All plots exhibited TSS enrichment, and both control and slag-only plots showed significant TP and TN enrichment. In contrast, slag-and-biochar plots exhibited lower TP enrichment and generally reduced TN enrichment, though not significantly. Observed spatial and seasonal variability influenced performance, highlighting the need for continued field-scale evaluation of bioreactor effectiveness under variable conditions
‘Cog in the machine’ or social being? How digital communications affect social capital development in higher education institution workplaces.
No full textThe purpose of this research is to investigate the impact of digital communications on social capital development within the workplace in public institutions of higher education. While previous literature recognizes the potential implications of the internet on areas like social capital (Putnam, 2000; 2020) and formal and informal communications in organizations (Simon, 1997), an in-depth understanding of how modern digital communications impact social capital development is still necessary to address the gap in literature and to analyze the impact of digital communications on the development of organizational social capital. The potential implications of this work on scholarly research include expanding understanding of the connection between digital communications and social capital development, opening avenues for future research to look further into conceptual connections with organizational culture, and providing advancement for connecting theoretical approaches and practical application in public administration. This research could have an important impact on the application of communication policies and practices that can be utilized in the workplace to promote stronger, positive relationships between employees that also have a positive effect on the organization’s culture
An evaluation of performance coated glass for potential use in airport traffic control tower cab glazing systems
No full textThe Federal Aviation Administration (FAA) limits Airport Traffic Control Tower (ATCT) cab window glass to only annealed, uncoated, and low-iron Soda-Lime-Silica Glass (SLSG). Although this type of glass offers many benefits to air traffic control, it presents numerous challenges such as poor thermal performance and relatively high reflective properties. Despite the flawless appearance of this glass; its surfaces contain microscopic cracks which act as stress intensifiers causing diminished strength when exposed to water vapor under flexural bending. This research evaluated Low-Emissivity (Low-E), Antireflective (AR) and Self-Cleaning (SC) coatings applied to low-iron glass by both Magnetron Sputter Vacuum Deposition (MSVD) and Chemical Vapor Deposition (CVD) for use in ATCT cab glazing systems. The theorized complementary structural benefits of CVD coated glass were also investigated. Compared to uncoated low-iron, the AR glass exhibited a 3.91% increase in Visible Light Transmittance (VLT) and 3.83% decrease in Visible Light Reflectance (VLR). The AR coatings negligibly impacted transmission of Signal Light Gun (SLG) illuminates with color changes near or below the level of human perception. The self-cleaning glass demonstrated slightly higher transmitted SLG color deviations along with a 3.31% decrease in VLT and 4.84% increase in VLR. The highest SLG color deviations and VLT reductions were associated with the Low-E group. Test data was used to develop a regression model estimating the transmitted SLG color change through any type of glass using chroma as the independent variable. It was estimated that a maximum 2.95 glass chroma would result in aviation compliant SLG transmissions. Structural investigations suggested that CVD coated glass inhibit environmentally induced stress corrosion. This is substantiated by test results indicating flexural strength increases of artificially weathered CVD coated specimens of 14.8%, 16.2%, and 16.4% at probabilities of failure of 0.50, 0.008, and 0.001, respectively. These strength increases were contradictory to testing conducted on new glass under a higher loading rate where the CVD coated glass revealed a 22.80% reduction in the mean failure strength. These findings are not necessarily applicable to exterior glazed units and do not negate aforementioned strength increases
Modeling the ballistic performance of laser-powder bed fusion additively manufactured 316L stainless steel targets with as-built residual stresses
No full textThe leveraging of part scale thermal effects models to predict the impact of residual stresses and part distortion induced in laser-powder bed fusion (L-PBF) additively manufactured (AM) components can be an effective means for determining how an AM component will behave in an application with harsh loading conditions such as high strain-rates. Therefore, this work develops a sequentially-coupled thermomechanical finite element (FE) workflow for predicting the impact of thermal effects on the dynamic loading response of L-PBF 316L stainless steel components. The initial task was to develop the additive manufacturing process event series generations code, AMPES, to create raster scanning paths for the heat source that mimic the laser during the L-PBF process. To demonstrate the utility of AMPES and the part scale thermomechanical FE workflow’s viability, pilot work modeling the thermal history of a bridge specimen printed out of 316L and the residual stress state of an L-shape part printed out of Inconel 718 with previously published neutron diffraction data was conducted. The pilot work showed that AMPES could reliably mimic the raster scanning strategy of the laser in L-PBF, determined that an isotropic temperature dependent linear elastic-perfectly plastic (EPP) material model had sufficient fidelity for capturing the thermal effects in a part scale model, and that a sparse thermal history method is needed for modeling full AM components in a reasonable amount of time. Furthermore, though it was determined that EPP is sufficient for capturing the thermal effects of L-PBF, EPP is not suited for predicting dynamic loading with its inability to capture plastic hardening. Therefore, a series of experiments were conducted to calibrate a Johnson-Cook (JC) strengthening model to L-PBF 316L that was then validated by Taylor anvil experiments. Finally, the part scale thermal effects FE workflow was used to model the residual stresses induced on a L-PBF 316L plate used in a ballistic test. A key takeaway was that imposing residual stresses only slightly reduced the energy absorption capacity of the ballistic impact predictions using the L-PBF 316L JC model as opposed to neglecting the residual stresses. Both predictions were validated by experiments
Inductively heated platinum electrodes
No full textThis dissertation presents the fabrication and application of a 150 micrometer platinum microelectrode for induction heating, with a copper coil generating the electromagnetic field and the heating process controlled using pulse width modulation technique (PWM) to regulate the duty cycle of a high-frequency signal. Electrochemical characterization, including resonance frequency determination, peak-to-peak potential optimization, and scan rate variation, is conducted using a 5 mM [Ru(NH3)6]2+/3+ solution in 0.1 M KNO3 to calibrate current variations with changing duty cycles, while the temperature increase (delta T) is estimated using the Seebeck coefficient of [Ru(NH3)6]2+/3+. The study further explores the application of induction heating for enhancing the sluggish oxygen reduction reaction (ORR), which is vital for fuel cells and metal-air batteries. Temperature calibration is performed in 50 mM H2SO4 and 50 mM HClO4 under 20 Vpp and 30 Vpp applied induction heating potential conditions, where H2SO4 enables higher temperature rises but damages the platinum electrode, while HClO4 allows heating up to 80 degrees Celsius before electrode poisoning occurs. Electrochemical data confirm increases in the ORR diffusion coefficient and rate constant, highlighting the potential of PWM controlled heating for reaction enhancement. Additionally, the impact of electrode positioning on electrochemical parameters is examined by comparing vertically and horizontally positioned electrodes, with the latter exhibiting lower temperature increases (maximum 65 degrees Celsius) due to reduced convection. COMSOL Multiphysics simulations confirm similar heat generation and transfer for both orientations, emphasizing the role of convective differences in temperature variations. Finally, a novel temperature pulse voltammetry (TPV) technique is introduced to analyze reaction kinetics and thermodynamics, where induction heating with a 10 Vpp potential in a home-built system resulting in minimal temperature increases, and the highest current response at 975 msec suggests residual heat transfer within the electrode’s epoxy matrix