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Effect of wind turbulence on wind ballistic trajectory of a medium calibre weapon system
Get PDFGoyder, Hugh - Associate Supervisor
Helliker, Aimee - Associate SupervisorCurrent ballistics and Fire Control Systems (FCS) use the assumption that crosswind located at the firing point will be constant between firing point and target location. The single constant crosswind value is then used to calculate the ballistic drift offset required to correctly engage a target at range and maintain an accurate firing solution. Variations in crosswind speed and direction are not considered by FCS but are known to cause drift errors in flight and offset the resulting impact point, the error is commonly known as gustiness.
Applying a variable crosswind drift correction for both time of flight and projectile height could produce an improved result by considering variations in the crosswind dynamics. Using multiple crosswind sensors at difference heights, a wind gradient curve can be produced to model wind turbulence and speed variations in reference to the projectile trajectory height. Similarly, changes in the crosswind can be modelling against the engagement timeline to show gustiness in relation to the time of flight of the projectile.
The accuracy and performance of the new ballistic model can be measured against the NATO standard coincidence window, which is used to evaluate FCS accuracy. The NATO error window of 0.3 mrads can be used to measure the probability of hit between the current constant crosswind and the new variable crosswind FCS model (US Army Aberdeen Test Center, 2009b). Using a reference tank target at a nominal distance of 2,000 meters, gives a coincidence window requirement of 60 cm square located on target centre mass.
The thesis found for the reference projectile used, a 40CTAS 40 mm round (CTA International, 2018b), that the FCS accuracy could be improved by 10.95% when including variations in the crosswind. The probability of hit inside the NATO coincidence window is improved to 56.16% when using crosswind at the instant of firing, compared to holding a single constant value during the engagement timeline.
It was also found that dynamic crosswind conditions can be included and modelled into a Point Mass Ballistic Model. Variations in the crosswind gradient curve can be used to assess turbulence and change in wind conditions. The wind gradient curve also demonstrates that wind conditions are not constant in relation to both time and height above ground, during an engagement sequence
Why the Afghan and Iraqi armies collapsed: an allied perspective
Get PDFRather than military factors, American and Western liberal ideas (ideological views) and politics explain many of the obstacles faced in rebuilding the Afghan and Iraqi Armies. Liberal ideas largely determined what options the coalition would use. Ideological factors help explain democratization and reconstruction challenges, partner leaders with divergent aims, military-cultural factors and the Western combat focus, politicization, corruption, and nepotism. This article reviews the differences between Western liberal democracies and partner states, the politics of counterinsurgency, and army accounts. This article will assist US practitioners in security cooperation, institutional capacity building, and security assistance.The US Army War College Quarterly: Parameter
Thermochemical characterisation of hydrochar from agricultural waste and its efficiency as a supplement with solid fuel
Get PDFCircular approaches to revalorise waste biomass from agriculture and food production sectors are crucial for developing a sustainable bioenergy strategy. For instance, while the demand for edible mushroom cultivation has increased globally, the production generates a substantial amount of waste biomass, known as Spent Mushroom Substrate (MS). Thermochemical biomass conversion technologies such as hydrothermal carbonisation offers a robust strategy to produce “hydrochar” from the wet biomass and can be used downstream for various environmental applications. In this study, we assess the feasibility of MS-derived hydrochar for energy application, specifically as a blend with coal. The key parameters for the hydrochar production such as temperature, time and moisture content were optimised (205 °C, 3.65 h, and 73.18%, respectively) using a statistical tool “Response Surface Methodology (RSM)” to obtain a carbon material with higher yield and calorific value. The hydrochar from MS exhibited an acidic pH (4.42), increased fixed carbon content (23.7%), reduced sulphur content (0.26%), coarser porous surface, enhanced oxygenated functional groups (hydroxyl, carboxyl and ketonic) and the formation of minerals like Sodium Carbonate (NaCO3), whewellite (CaC2O4·H2O) and gypsum (CaSO4). Combustion behaviour of hydrochar was also assessed using calorimetry and thermogravimetry, specifically to test different coal and hydrochar blends on the feasibility of using hydrochar as a supplement to conventional solid fuels. Our results suggest that a blend of 20% hydrochar with 80% coal as an ideal blending ratio (with a calorific value of 27.65 MJ kg−1) highlighting the use of hydrochar as supplement with conventional fuel like coal.Biomass and Bioenerg
Numerical and experimental investigations of diffusion-induced boundary layer separation on aero-engine nacelles
No full textAero-engine nacelles have to fulfill design requirements at both cruise and off-design conditions. Under engine windmilling conditions the ingested streamtube massflow is relatively low. A key off-design condition is take-off, which, in conjunction with an engine windmilling scenario, results in the stagnation point of the ingested streamtube being located significantly inside the intake. The combination of high angle of attack and low engine massflow rates leads to a strong flow acceleration and subsequent diffusion of the boundary layer on the upper quadrants of the external nacelle cowl, which can terminate with subsonic separation from the leading-edge. Under this condition, Reynolds number effects can play a dominant role on the separation onset and characteristics and 3D-annular wind tunnel tests cannot always achieve Reynolds’ number equivalent to full scale. A novel quasi-2D rig configuration representative of the aerodynamics of a full-size aero-engine nacelle under windmilling end of runway conditions examined in detail the characteristics of the boundary layer on the external cowl of a nacelle prior to diffusion-induced separation. Separation of the boundary layer was independently promoted through changes to represent different engine massflow rates and freestream Mach number on the rig to determine the limits of steady Reynolds Averaged Navier Stokes (RANS) methods to discern the onset of boundary layer separation. For the conditions and geometry investigated, the combined experimental and computational results showed that there was laminar to turbulent transition of the boundary layer ahead of the subsonic diffusion. The work showed that steady RANS can predict the onset of boundary layer separation with an uncertainty of approximately 10% on notional engine massflow rate and 0.05 on freestream Mach number relative to a nominal operating freestream Mach number of 0.25. This provides guidance for the industrial design and optimization of future windmilling-tolerant nacelles for large ultra-high bypass ratio turbofan engines.This project has received funding from the Clean Sky 2 Joint Undertaking (JU) under grant agreement number 101007598. The JU receives support from the European Union’s Horizon 2020 research and innovation programme and the Clean Sky 2 JU members other than the Union.International Journal of Heat and Fluid Flo
Understanding the explosion risk presented by ammonium nitrate and aluminium home-made explosives detonated as surface charges in hexahedral main charge containers
Get PDFAmmonium nitrate and aluminium (AN–Al) has been used as a typical homemade explosive (HME) by non-state actors since the turn of the century. Despite the regulation applied to ammonium nitrate above 16% nitrogen content and an aluminium particle size below 200 µm, their use has been widespread in Afghanistan, Columbia, Iraq, Syria and Yemen. Containers used to utilise AN–Al as a man-portable improvised explosive device (IED) are typically hexahedral in shape, not the spherical or hemispherical geometries used to theorise risk mitigation. This is particularly important in post-blast investigation where explosives of a non-ideal nature are often used in non-spherical containers.
Given the breadth of HME available to criminals, the explosion performance of forty hexahedral containers filled with AN–Al of unknown manufacture is examined. Performance of the AN–Al is determined through the surface detonation of these containers on alluvial soil, with apparent crater volume compared to theoretical calculations for spherical charges of TNT detonated in that same medium. A conversion factor for hexahedral main charges to spherical charges is then established to achieve more accurate predictions of the explosion risk using Kingery-Bulmash and Bowen curves. The paper provides worked examples for practical application and a methodology by which predictions of charge mass in other mediums such as asphalt can be determined.Discover Material
Elucidating the impact of environmental factors on the growth of Colletotrichum coccodes strains isolated from potato tubers in Great Britain
Get PDFBlack dot and silver scurf caused by Colletotrichum coccodes and Helminthosporium solani, respectively, are tuber blemish diseases affecting quality in the fresh and pre-pack potato industry. In the last 20 years, the importance of high-quality tuber appearance has increased considerably due to the growing demand for washed and pre-packed potatoes in the UK. Changing climate characterised by rising temperatures and wetter summers is a threat as this will favour the development of pathogens such as C. coccodes in the soil increasing the risk of food spoilage. Moreover, both diseases can develop not only in the field but also after harvest, with postharvest storage temperatures being a crucial factor in controlling fungal growth. Furthermore, anecdotal evidence showed differences on the aggressiveness of black dot depending on its origin (i.e. England and Scotland) on potato tubers. Silver scurf and black dot are difficult to differentiate as they present similar phenotypes characterised by silvery lesions making it challenging for managers to take the necessary corrective action during storage. Hence, the aim of this study was to give a general insight into the ecological conditions affecting the establishment of the causal agent of potato black dot in the field, and black dot and silver scurf during the supply chain. Therefore, in vitro experiments were designed to study the growth rate and lag times simulating both scenarios respectively: on soil extract agar (SEA) media at different temperatures (4, 11, 15 °C) and matric potentials (control [unmodified] and − 1.4 MPa [modified]); and on natural potato dextrose agar (NPDA) for different temperatures (4, 11, 15 and 20 °C) at 99 % relative humidity (RH) for 25 days. When simulating the field environment, drier conditions (matric potential = −1.4 MPa) reduced fungal growth for both isolates by 0.1 cm day−1 at the temperature of 15 °C, suggesting temperature as the main limiting factor for the growth of C. coccodes in the soil. The causal agent of black dot exhibited a faster growth rate under retailer-like conditions (i.e., 15 °C) compared to H. solani. Understanding the environmental influence on both the pathogen and the crop is vital for proper disease management to help reduce food loss and waste.International Journal of Food Microbiolog
Navigating sustainability through institutional change: consolidating and expanding the debate
Get PDFSustainability has become a crucial topic of discussion in both academia and practice. One
perspective for understanding sustainability is through the lens of institutional change, which
emphasises the need to transform norms, values, and practices to fully embrace sustainability.
This review article contributes to the ongoing scholarly discourse by synthesising current
literature at the intersection of institutional change and sustainability. Utilising a systematic
approach, a total of 108 articles were analysed. The review provides a comprehensive
understanding of the discourse and categorises existing knowledge into four key themes:
triggers for change, change agents, methods for change, and resulting outcomes. This reveals
the multifaceted nature of sustainability attainment through institutional change. Additionally,
the review introduces four distinct institutional change models that explore change by
considering the interaction between existing institutions and new sustainable institutions
during the change process. This highlights the role of the existing institutional framework and
the complexity of achieving sustainability. Finally, the review identifies research gaps and
suggests future directions for further research in this field
Dataset "Martlewetal2023_Data"
No full textThe intensification of arable agriculture has resulted in an increase in vehicle wheel load and the intensity of field operations, which has increased the risk and
incidence of degradation in physical properties of the uncultivated subsoil layer. Biopores generated by the long-term, repeated use of specific cover crops
within an arable rotation has been suggested as an approach to improve subsoil physical properties. Therefore, this paper aimed to determine the impact of
long-term repeated cover cropping and the interaction of rotation treatments with different cultivation approaches on subsoil physical properties. Data was
collected at the NIAB ‘Sustainable Trial for Arable Rotations’ long-term, rotation and cultivation field experiment established in 2006. Rotation treatments
comprised a brassica cover crop alternated annually with winter wheat (ALTCC) compared to continuous winter wheat (CWW). Cultivation treatments
comprised PLOUGH (250 mm depth), and non-inversion cultivation at 250 mm (DEEP) and 100 mm (SHALLOW) depths. Penetration resistance and volumetric
soil moisture were collected at bi-monthly intervals during the 2018/19 growing season. Undisturbed soil cores were collected for laboratory analyses of soil
water retention, water stable aggregates, root morphology digital scanning and biomass, and X-ray computed tomography (CT). Results showed that
treatment ALTCC combined with SHALLOW, resulted in lower penetration resistance and increased moisture in the subsoil. This increased subsoil moisture
persisted later into the season compared to the control. SHALLOW increased subsoil water retention, improved subsoil root morphology and increased
subsoil porosity. Benefits from treatment ALTCC were not observed where combined with higher intensity, deeper cultivation. Overall, the combination of
treatments ALTCC with SHALLOW, produced significant benefits to subsoil physical properties.The Felix Thornley Cobbold Trust, The Chadacre Trust, The Morley Agricultural Foundation and NIA
Investigating performance of hybrid photovoltaic–thermal collector for electricity and hot water production in Nigeria
Get PDFThe research work explores the impact of temperature on Silicon photovoltaic (PV) panels, considering Nigeria as a case study. It is found that high solar radiation in Nigeria increases the surface temperature of PV panels above 25 °C of the optimal operating temperature. The redundant energy gain from solar irradiance creates heat at the rear of solar panels and reduces their efficiency. Cooling mechanisms are therefore needed to increase efficiency. In this study, we demonstrated a unique hybrid system design employing a heat exchanger at the back of the panel, with water circulated through the back of the PV panel to cool the system. The system was simulated using TRNSYS at three locations in Nigeria—Maiduguri, Makurdi, and Port Harcourt. The results of the peak annual electrical power output in Maiduguri give a power yield of 1907 kWh/kWp, which is the highest, due to a high solar radiation average of 727 W/m2 across the year. For Makurdi, the peak annual electrical power output is 1542 kWh/kWp, while for Port Harcourt the peak power output is 1355 kWh/kWp. It was observed that the surface temperature of Polycrystalline Si-PV was decreased from 49.25 °C to 38.38 °C. The electrical power was increased from 1526.83 W to 1566.82 W in a day, and efficiency increased from 13.99% to 15.01%.Energie
Effects of surface hardening by laser shock peening and shot peening on a nickel-based single-crystal superalloy CMSX-4
Get PDFImproving the expected life of nickel-based single-crystal superalloy turbine components by surface hardening treatments including laser shock peening (LSP) and mechanical shot peening (MSP) are of particular interest for mitigation of life limiting damage such as environmental assisted cracking in hot section components of gas turbines. In the present study the effects of LSP and MSP on the surface roughness, microhardness and work hardening of a nickel-based single crystal superalloy CMSX-4® have been assessed. Surface roughness was measured using laser profilometry. The degree of work hardening was measured using electron backscattered diffraction with local misorientation analysis. The analysis showed evidence for a work hardening layer in the MSP sample to a depth of approximately 70 μm. Sets of slip bands extending far into the bulk of the sample were observed in the LSP-treated sample, without any evidence of a work hardening layer. Microhardness measurements used to gauge the depth of residual stress showed that LSP produced a much deeper hardness profile than MSP, with compressive residual stress depths of 1000 μm and 200 μm in LSP and MSP respectively. The retention of hardness after a heat treatment of 50 h at 700 °C was more prominent in the LSP sample than in the MSP sample. LSP and MSP have therefore been shown to be at the opposite ends of the spectrum of surface hardening treatments of CMSX-4, with LSP giving milder hardening, but to a greater depth.The authors would like to thank the Engineering and Physical Science Research Council for financial support of the research work (Grant number EP/ I033246/1) and Rolls-Royce Plc for providing the bare material, for their technical support and useful discussionsMaterials Research Expres