Relevant bibliographies by topics / Fragmentation upon impact

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  1. Journal articles
  2. Dissertations / Theses
  3. Books
  4. Book chapters
  5. Conference papers
  6. Reports

Academic literature on the topic 'Fragmentation upon impact'

Author: Grafiati
Published: 4 June 2021
Last updated: 9 February 2022

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Journal articles on the topic "Fragmentation upon impact"

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Victorov, S. D., A. N. Kochanov, and V. N. Odintsev. "Fragmentation of Coal Samples upon Intense Dynamic Impact." Bulletin of the Russian Academy of Sciences: Physics 83, no. 6 (June 2019): 673–76. http://dx.doi.org/10.3103/s1062873819060376.

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Rontani, J. F., and C. Aubert. "Fragmentation of 1-phenyl-2-alkylcyclobutanols upon electron impact." Organic Mass Spectrometry 28, no. 7 (July 1993): 795–96. http://dx.doi.org/10.1002/oms.1210280713.

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Vais, V., and A. Mandelbaum. "Stereospecific Fragmentation of 3-Dimethylaminocyclohexanols upon Electron Impact Ionization." Journal of Mass Spectrometry 32, no. 7 (July 1997): 750–54. http://dx.doi.org/10.1002/(sici)1096-9888(199707)32:7<750::aid-jms527>3.0.co;2-y.

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Guccione, Davide Ettore, Klaus Thoeni, Stephen Fityus, François Nader, Anna Giacomini, and Olivier Buzzi. "An Experimental Setup to Study the Fragmentation of Rocks Upon Impact." Rock Mechanics and Rock Engineering 54, no. 8 (June 5, 2021): 4201–23. http://dx.doi.org/10.1007/s00603-021-02501-3.

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Golosov, Grigorii V., and Kirill Kalinin. "Presidentialism and legislative fragmentation: Beyond coattail effects." British Journal of Politics and International Relations 19, no. 1 (December 19, 2016): 113–33. http://dx.doi.org/10.1177/1369148116682654.

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Using data from a nearly comprehensive set of the world’s electoral democracies, 1992–2014, this article empirically evaluates the impact of presidentialism upon legislative fragmentation. The analysis demonstrates that the impact is strong, consistent across a wide variety of political contexts, and conditioned by the type of presidential regime, the scope of presidential powers, electoral system effects, and essential party system properties. While much of the reasoning regarding the interplay between presidentialism and legislative fragmentation has been traditionally focused on short-term coattail effects of presidential elections, this study shows that these effects are real, but they are insufficient to make a significant impact upon the parameter of crucial importance for the functioning of presidential regimes: the number of parties in the legislature. The main impact of presidentialism is systemic, stemming from its tendency to restrict the number of parties to a limited set of viable competitors for the presidential prize.
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Herrmann, Michael, and Gerhard W. Fischer. "Fragmentation of 1-aryl-5-(2-dialkylaminovinyl)-1H-tetrazoles upon electron impact." Organic Mass Spectrometry 24, no. 9 (September 1989): 823–29. http://dx.doi.org/10.1002/oms.1210240917.

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Medina-Franco, José Luis, Cecilia Juárez-Gordiano, Alicia Hernández-Campos, Georgina Duarte-Lisci, Margarita Guzmán, and Rafael Castillo. "New fragmentation processes of pyridin-2(1H)-ones upon electron impact ionization." Rapid Communications in Mass Spectrometry 19, no. 16 (2005): 2350–54. http://dx.doi.org/10.1002/rcm.2059.

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Ye, Yang, Klaus Thoeni, Yawu Zeng, Olivier Buzzi, and Anna Giacomini. "Numerical Investigation of the Fragmentation Process in Marble Spheres Upon Dynamic Impact." Rock Mechanics and Rock Engineering 53, no. 3 (September 30, 2019): 1287–304. http://dx.doi.org/10.1007/s00603-019-01972-9.

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Wang, Yuannian, and Fulvio Tonon. "Discrete Element Modeling of Rock Fragmentation upon Impact in Rock Fall Analysis." Rock Mechanics and Rock Engineering 44, no. 1 (July 27, 2010): 23–35. http://dx.doi.org/10.1007/s00603-010-0110-9.

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Sekiguchi, Osamu, Toshiyuki Kosaka, Takeshi Kinoshita, and Susumu Tajima. "Fragmentation of organosulfur compounds upon electron impact: 2-mercaptoethanol and 1,2-ethanedithiol." International Journal of Mass Spectrometry and Ion Processes 145, no. 1-2 (July 1995): 25–33. http://dx.doi.org/10.1016/0168-1176(95)04165-h.

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Dissertations / Theses on the topic "Fragmentation upon impact"

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Canessi, Tomà. "Physical modelling of rock fragmentation upon impact." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.

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Rockfall represents a significant safety hazard in building, civil and mining environment that can cause serious injuries and fatalities and can damage structures, infrastructure and machinery. It is extremely costly to manage and public authorities need reliable tools to study and design protection structures as the performance of the existing structures are variable. Many studies and experiments have been done, but one aspect would lead to a better comprehension of the subject: the fragmentation of blocks upon impact. Rocks commonly break up upon impact but rockfall prediction models currently available mostly ignore this phenomenon, even though fragmentation changes size, shape and energy of falling blocks and can drastically change the outcome of the design of protective structure. For example, if a large rock breaks upon impact and its mass and energy are divided among fragments, a high level of energy is dissipated and ignoring fragmentation would lead on an overdesign of the protection barrier. Moreover, very fast rock fragments may rupture a rockfall protection. The project aims to overcome this limit, studying and considering fragmentation in rockfall model, allowing assessment of the hazard rising from a shattered rock. The intention is to develop a database of experimental data about fragmentation of blocks upon impact by considering the initial conditions that cause fragmentation, the fragment size and mass distribution, the partition of velocity and energy at impact and what may lead to “bullet effect” or high flying fragment. This project aims to include fragmentation in rockfall prediction causes to facilitate a better and safer mitigation of rockfall hazard. Moreover, a better knowledge will directly translate into economical and societal benefits, such as more cost effective and better user experience.
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Ciccone, Giuseppina. "Experimental study of artificial blocks under dynamic fragmentation." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.

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Rockfall represents a significant hazard not only in mountainous areas, but also alongside coastal routes, major transport infrastructures and quarry faces. One aspect of the rockfall phenomenon that still requires further investigations is the fragmentation of falling blocks upon impact. The changes in size, shape and energy of the falling blocks upon fragmentation and the variation in trajectory of the fragments can seriously affect the optimization design of the rockfall mitigation measures. The fragmentation of boulders during a rockfall event can lead to significant changes in the global run-out distances and the maximum kinetic energy to be accounted in the protection systems design. This thesis presents an experimental program conducted to investigate the fragmentation phenomenon under controlled conditions to provide some useful insights in terms of block survival probability upon dynamic impact, fragments distribution, post impact velocity and energy dissipation upon impact. The result of this thesis will focus on a detailed description of the fragmentation process and study several fragmentation mechanisms involved, reproducing many experimental observations of fragment shapes and impact energy, and significantly improve the understanding of the fragmentation process for impact fracture. Spheres shapes were chosen because of their simple body geometry and consequent impact and stress field symmetry. So, the description of materials, sample preparation and tests program conducted for 175 mortar spheres of different diameter built for the current research will be presented to evaluate the survival probability of homogeneous artificial rocks with a known compressive strength dropped from a certain height and to observe the fragmentation process upon impact with a known impacting energy.
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le, Brasseur Richard. "Transitional landscapes : examining landscape fragmentation within peri urban green spaces and its impacts upon human wellbeing." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31257.

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Transitional land uses produced through urbanisation continue to change the landscape and fragment ecological structures including green spaces across Europe (Nilsson et al., 2013). Green spaces offer significant benefits to humans, contributing to wellbeing and life satisfaction (Taylor, 2002). The understanding of how these unique green spaces spaces function and provide benefits to humans, and how landscape change in peri-urban contexts affects their performance, is important. The scope of this research is to contribute to an understanding of landscape fragmentation within some of Europe's polycentric urban regions, their peri-urban green spaces, and the associated impacts upon human quality of life. Two urban regional case studies, Paisley near Glasgow, Scotland, and Vantaa, near Helsinki, Finland were analysed and compared. The results indicate that humans interacting with more physically or ecologically fragmented peri-urban green spaces have higher self-reported life satisfaction levels. Though no statistically significant characteristics were apparent between life satisfaction and fragmented green space characteristics, this research was able to identify those specific structural attributes and physical characteristics of interstitial peri-urban green spaces within a polycentric region in a fragmented state that contribute to the physical, social, and psychological aspects of human wellbeing. The statistically significant eco-spatial characteristics of polycentric peri-urban interstitial green spaces that are reported to impact human wellbeing are the size, proximity, maintenance and management, and the level of greenness within its vegetation composition and setting. Overall, a spatially diverse, fragmented, peri-urban landscape whose green spaces are extensively sized, naturalistically shaped with horizontal vegetation and normal sized edges, most often parks or woodlands or forests which are integrated and physically connected to another green space which is moderately clean and somewhat safe as well as being located close to or adjacent to a heavy-trafficked road provide the most human wellbeing benefits.
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Hatfield, Jack Henry. "The impacts of habitat loss and fragmentation upon the maintenance of biodiversity in tropical ecosystems." Thesis, Imperial College London, 2018. http://hdl.handle.net/10044/1/63830.

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Habitat loss and fragmentation are major threats to biodiversity on a global scale. Human modified landscapes now comprise large areas of the globe, heavily contributing to the observed decline in biodiversity. By understanding the processes governing species communities in these fragmented landscapes we may be better able to manage them in a way that provides conservation benefits. The first part of this thesis focuses on dispersal in complex landscapes with Chapter 2 taking a regional view, examining connectivity across the whole Brazilian Atlantic Forest from a functional perspective and Chapter 3 investigating movement within local landscapes. We found that from the perspective of its fauna the Brazilian Atlantic Forest is functionally fragmented, with few areas remaining that are able to support large populations. At the local scale species exhibited clear threshold responses to changing forest cover with dispersal ability and home range size important determinants. The second part analyses bird diversity patterns across fragmented landscapes. Chapter 4 looks at alpha-diversity and composition, considering different land-uses and habitat types across a fragmentation gradient. Chapter 5 examines beta-diversity within habitats as well as between habitat types and landscapes. Bird community composition was found to differ between land use types as well as between habitats. Plantation forest matrices were able to mitigate isolation and area effects, retaining forest species. Beta-diversity within habitats was found to remain constant, whereas between habitat beta-diversity was high when comparing contrasting habitats. Turnover between habitat types is able to offset decreases in alpha-diversity, contributing to the maintenance of gamma-diversity. At the landscape level dissimilarity patterns were heavily governed by forest cover, suggesting a range of habitat amounts are needed to preserve the full bird community. Overall, although habitat loss and fragmentation are highly detrimental for biodiversity, mitigation via management changes are possible.
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Books on the topic "Fragmentation upon impact"

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Wright, Almeda. The Spiritual Lives of Young African Americans. Oxford University Press, 2017. http://dx.doi.org/10.1093/acprof:oso/9780190664732.001.0001.

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The Spiritual Lives of Young African Americans unearths the ways that African American Christian youth separate their lives and spirituality into mutually exclusive categories, with the result that their religious beliefs and practices do not directly impact their experiences of communal and systemic injustices. Yet this work argues that youth can and do teach the church and society myriad lessons through their theological reflections and actions. This book takes seriously the harsh realities of African American youth, who are often marginalized and even dehumanized within society and religious institutions. It draws upon in-depth theological reflection with adolescents and recent research on adolescent spirituality to examine the crucial role of spirituality in adolescent identity formation and the practical ways that youth negotiate the world around them. Listening to the voices of young African Americans, including activist and poets, pushes us to consider specific examples of fragmentation, including how young African Americans can reconcile their faith in God with their experiences of police brutality and ongoing violence. In conversation with young African Americans, this book also mines the resources of African American religious and theological traditions, and shows how collectively they can help youth to navigate fragmentation and respond to systemic injustice. In particular, abundant life, or choosing the way of life abundant, offers a vision of life and hope for young people who are too often surrounded by death. This work concludes with a critical pedagogy for integrating spirituality and fostering abundant life with African American youth.
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Frankham, Richard, Jonathan D. Ballou, Katherine Ralls, Mark D. B. Eldridge, Michele R. Dudash, Charles B. Fenster, Robert C. Lacy, and Paul Sunnucks. Population fragmentation causes inadequate gene flow and increases extinction risk. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198783398.003.0005.

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Most species now have fragmented distributions, often with adverse genetic consequences. The genetic impacts of population fragmentation depend critically upon gene flow among fragments and their effective sizes. Fragmentation with cessation of gene flow is highly harmful in the long term, leading to greater inbreeding, increased loss of genetic diversity, decreased likelihood of evolutionary adaptation and elevated extinction risk, when compared to a single population of the same total size. The consequences of fragmentation with limited gene flow typically lie between those for a large population with random mating and isolated population fragments with no gene flow.
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Book chapters on the topic "Fragmentation upon impact"

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Jackson, Peter. "The Era of Inter-Mongol Warfare." In The Mongols and the Islamic World. Yale University Press, 2017. http://dx.doi.org/10.12987/yale/9780300125337.003.0008.

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This chapter examines the conflicts among the Mongol successor-states that developed after 1260, along with the turbulent activities of nomads within such states and the measures of reconstruction that the various Mongol regimes put in place. It begins with a discussion of the Mongol empire's fragmentation into four virtually independent khanates, where the conquered Muslims of the empire were now divided: the dominions of the ‘Great Khan’ (qaghan) in China and Mongolia proper; the Ilkhanate in Iran, Iraq and Anatolia; the ulus of Chaghadai in Central Asia; and the ulus of Jochi in the western steppes. The chapter then considers the relationship between the khans and the qaghans, the problems of warfare between different Mongol khanates, and the Jochids' incursions into Ilkhanid territory. It also explores the impact of the inter-Mongol warfare upon the agrarian and urban economy of the Islamic world.
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Gelderblom, Oscar. "Introduction." In Cities of Commerce. Princeton University Press, 2013. http://dx.doi.org/10.23943/princeton/9780691142883.003.0001.

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This book explores the impact of urban competition on the institutional foundations of international trade in the Low Countries during the period 1250–1650, with particular emphasis on local and foreign merchant communities in Bruges, Antwerp, and Amsterdam. The book offers an alternative explanation for institutional change in European commerce that is not predicated upon the existence of strong territorial states or the ability of merchants to create private order solutions. Instead, it argues that the very problem of premodern Europe's political and legal fragmentation also produced its solution in the form of open access or inclusive institutions that made it easier for merchants to deal with violence and other conflicts. This introductory chapter considers the dynamics of institutional change, focusing on the link between state formation and the growth of trade, foreign traders' use of private order solutions to prevent violent assaults or the opportunistic behavior of their agents without the support of sovereign rulers, and urban competition between commercial cities in the Low Countries.
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Jordan, Shirley. "The Time of Our Lives." In What Forms Can Do, 113–30. Liverpool University Press, 2020. http://dx.doi.org/10.3828/liverpool/9781789620658.003.0008.

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This chapter explores some of the formal devices elaborated in recent contemporary women’s life writing to convey a sense of time and of being in the world. It focuses on the intimate and the everyday and on the units, flows, categories and organization of time in recent experimental works by Annie Ernaux, Camille Laurens and Chantal Akerman. The chapter is grounded in theory about female-authored self-narrative, returns to gendered ideas of a hierarchy of time and builds upon the problematizing of linear time in what Julia Kristeva famously referred to as ‘women’s time’ (1979). It analyses in particular the functions of repetition, variation and fragmentation as forces that drive and shape the works in question, asking how such repetition might be read as specifically gendered, and examining the impact this might have on the experience of reading. The chapter explores the temporal architecture of three selected works which, I argue, are ‘time rich’ and ‘time sensitive’ and which loop back into each author’s previous life writing experimentation. These are Ernaux’s total life-narrative Les Années (2008), Laurens’s autofictional essay Encore et jamais: variations (2013) and Akerman’s final experiment in life writing, Ma mère rit (2013).
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Zucchini, Francesco, and Andrea Pedrazzani. "Italy: Continuous Change and Continuity in Change." In Coalition Governance in Western Europe, 396–447. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198868484.003.0012.

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Few democracies in the world have experienced so many transformations in the electoral and party systems as has Italy since the early 1990s. Therefore the study of the Italian case is an excellent opportunity to investigate if and how these changes impact on the government’s role in the decision-making process, on government formation and termination, and on the governance stage. Although the formal rules concerning executive–legislative relations have remained almost unaltered, since the 1990s Italian governments have increased de facto their agenda-setting power. Since 1994, the party competition dynamics and the electoral rules induced the political parties to build electoral alliances and pre-electoral coalitions. However, the persisting high level of internal fragmentation made Italian governments also very unstable compared to the governments in many other European democracies. The instruments of intra-coalitional conflict resolution used in Italy have been for long time quite informal and mostly based upon decision-making bodies partially external to the executive. The above cited changes at the beginning of the 1990s, by increasing the overlapping between government leadership and party leadership, made these mechanisms more internal to the government arena. Recent political and institutional developments—especially after the 2013 and 2018 general elections and the new electoral rules—leave very open and uncertain the prospects of consolidation of all these changes.
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Frankham, Richard, Jonathan D. Ballou, Katherine Ralls, Mark D. B. Eldridge, Michele R. Dudash, Charles B. Fenster, Robert C. Lacy, and Paul Sunnucks. "Population fragmentation causes inadequate gene flow and increases extinction risk." In A Practical Guide for Genetic Management of Fragmented Animal and Plant Populations, 49–64. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198783411.003.0004.

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Most species now have fragmented distributions, often with adverse genetic consequences. The genetic impacts of population fragmentation depend critically upon gene flow among fragments and their effective sizes. Fragmentation with cessation of gene flow is highly harmful in the long term, leading to greater inbreeding, increased loss of genetic diversity, decreased likelihood of evolutionary adaptation and elevated extinction risk, when compared to a single population of the same total size. The consequences of fragmentation with limited gene flow typically lie between those for a large population with random mating and isolated population fragments with no gene flow.
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Flores, Roberto Dante. "Hedonismo y Fractura de la Modernidad." In The Paideia Archive: Twentieth World Congress of Philosophy, 1–7. Philosophy Documentation Center, 1998. http://dx.doi.org/10.5840/wcp20-paideia199827443.

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This is an analysis of the ethico-cultural crisis of modernity and the emergence of the so-called postmodern aesthetic expressions (and conduct), examined principally from the point of view of Frederic Jameson and its coincidence with other authors (D. Lowe, G. Lipovetsky, and P. Virilio). I also investigate the relationship between the new sensitivities of the end of the century and the notion of justice, and its moral. This is seen by the authors as a consequence of the impact that mass-media technologies have produced in individuals leading to a new form of experience: the aesthetization of life and the fragmentation of the subject. The culture of the image is omnipresent, diluting art into aesthetization and the subject into the objectivization of consumption. We can see that there is a loss of historicity in the postmodern individual-originating from the speed of audiovisual information-upon perceiving, on a screen, the world in an instanct, without references to either a past or a future. The new technologies are the product of a new stage of capitalism, even more so than in the modernity of massive consumption. As a consequence of these three factors (aesthetization, ahistoricity, consumption), there has emerged a hedonistic ethos which differentiates itself from its modern vanguardist antecedents in that it is no longer the transgressor of a religious moral, or the secularism of duty, because pleasure is no longer forbidden. This framework, which is lacking in hard principles and is sustained by 'weak and conviction free' individuals is compatible with the liberal ethic of Rawls. In the face of the contradiction of modernity, we shall reconsider, as factors of socio-political construction, the moral values provided by the world's great religions.
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"enterprises are bound to gravitate towards the big cities and the need for marketed surplus beyond that obtainable from the state farms would re-inforce the already existent pattern of extreme concentration of modern inputs in the few agriculturally developed regions of the country. Fourth, it is unlikely to generate the order of urban employment that is required over the plan period. This failure has various ramifications. For one, un-employment would probably become increasingly worse in the smaller towns or else, the migration into the prime cities from other smaller urban centres would increase without, of course, affecting the overall employment outcome. For another, this would mean an exacerbatian of the social costs of such urbanisation, manifest in the forms of an expanding urban lumpenproletariat, prostitution, and begging. Clearly, none of these phenomena should have an extended life in a socialist system. Furthermore, such unemployment would undermine the utility of the rationing system which would fail to reach this needy class on account of their exchange entitlement failure. To meet the distributional objectives, therefore, it would become necessary to rely increasingly on institutional devices of income sharing as a strategic rather than purely tactical option. Case C: An Alternative This offers an alternative strategic framework for a revised DTYP. The central principle underlying this concerns what is adopted as a trinity of objectives, namely, growth, distributional equity, and grassroots participating institutions. The earlier cases are crucially dependent upon an extended circular flow of investible resources extracted from agriculture and invested in industry and related sectors in the form of large projects. This involves little direct participation on the part of the savers and investments occur largely outside the units or sectors from which resources are extracted. Inevitably, aggregate domestic investments would depend upon the open and hidden contributions of peasant agriculture which would also remain a net contributor or loser in resource terms. It is arguable that this type of investment process is unsuited to an economy like Ethiopia where the level of available investible surplus is low and scattered in small denominations, where the degree of economic fragmentation is extreme, and where even the relatively well-developed centre is unlikely to be able to bear the burden imposed upon it. In addition, this strategy is unmindful of harnessing for productive purposes those investible rural resources which are not extractable and therefore not useable through the centralised and dichotomous investment process mentioned above. The collective framework, that is, Case C, takes the relative emphasis away from major industrial investments and places it on investments within the rural sector. The industrial shift involves the locational, size, product and technology dimensions, making the sector less import-intensive and more labour-intensive. Thus, even if the scale of investment was to be lowered, there might be few net losses (in GDP terms) to output, and perhaps even a net gain in terms of intermediate-level skill creation, as well as in direct and indirect employment generated. This would ease the urban poverty." In The Agrarian Question in Socialist Transitions, 181–82. Routledge, 2013. http://dx.doi.org/10.4324/9780203043493-23.

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Conference papers on the topic "Fragmentation upon impact"

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Pálinkó, István, Gyula Tasi, and Béla Török. "Fragmentation patterns of α-phenylcinnamic acid derivatives upon electron impact ionization; a computational approach." In The first European conference on computational chemistry (E.C.C.C.1). AIP, 1995. http://dx.doi.org/10.1063/1.47671.

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Barletta, D., A. Marzocchella, P. Salatino, S. G. Kang, and P. T. Stromberg. "Modelling Fuel and Sorbent Attrition During Circulating Fluidized Bed Combustion of Coal." In 17th International Conference on Fluidized Bed Combustion. ASMEDC, 2003. http://dx.doi.org/10.1115/fbc2003-065.

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A simulation model of a circulating fluidized bed combustor, based on a one-dimensional description of bed hydrodynamics and a simplified formulation of the population balance equation on fuel and bed solids, has been set up. The model specifically aims at assessing the extent of fuel and sorbent attrition during circulating fluidized bed combustion of coal. Fuel attrition is modelled as a function of carbon loading and of the relevant operating variables while taking into account primary fragmentation of coal and secondary fragmentation and attrition by surface wear of its char. Modelling of sorbent attrition accounts for primary fragmentation of limestone upon calcination as well as attrition by surface wear of lime. To this end time- and conversion-dependent attrition rate is averaged over the sorbent particle lifetime in the reactor. Attrition submodels and their constitutive parameters are based on previous work by the research group in Naples. Coal char combustion and lime sulphation are modelled considering intrinsic reaction kinetics as well as boundary layer and intraparticle diffusion of reactants. The impact of attrition phenomena on the performance of the fluidized bed combustor is characterized by looking at carbon combustion efficiency, at sulphur capture efficiency, at the balance between bottom and fly ashes. The influence of operating parameters like fuel particle size, Ca/S ratio, gas superficial velocity, extent of air staging is investigated. The sensitivity of results of model computations to the parameters expressing fuel and sorbent attrition is presented and discussed.
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Fielding, Rebecca A., Reuben H. Kraft, X. G. Tan, Andrzej J. Przekwas, and Christopher D. Kozuch. "High Rate Impact to the Human Calcaneus: A Micromechanical Analysis." In ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-38930.

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An “underbody blast” (UBB) is the detonation of a mine or improvised explosive device (IED) underneath a vehicle. In recent military conflicts, the incidence of UBBs has led to severe injuries, specifically in the lower extremities The foot and ankle complex, particularly the calcaneus bone, may sustain significant damage. Despite the prevalence of calcaneal injuries, this bone’s unique properties and the progression of fracture and failure have not been adequately studied under high strain rate loading. This research discusses early efforts at creating a high-resolution computational model of the human calcaneus, with primary focus on modeling the fracture network through the complex microstructure of the bone and creating micromechanically-based constitutive models that can be used within full human body models. The ultimate goal of this ongoing research effort is to develop a micromechanics-based simulation of calcaneus fracture and fragmentation due to impact loading. With the goal of determining the basic mechanisms of stress propagation through the internal structure of the calcaneus, a two-dimensional model was employed for preliminary simulations with a plane-strain approximation. In this effort, a cadaveric calcaneus was scanned to a resolution of 55 μm using an industrial micro-computed tomography (microCT) scanner. A mid-sagittal plane slice of the scan was selected and post-processed to generate a 2D finite element mesh of the calcaneus that included marrow, trabecular bone, and cortical bone elements. The calcaneus was modeled using two-dimensional quadratic plane strain elements. A fixed boundary condition was applied to the portion of the calcaneus that, in situ, would be restrained by the talus. A displacement of 1.25 mm was applied to the heel of the calcaneus over 5 ms. In a typical result, following impact, the strain and stress are propagated throughout the cortical shell and then began to radiate into the bone into the bone along the trabeculae. Local stress concentrations can be observed in the trabecular structure in the posterior region of the bone following impact. Upon impact, cortical and trabecular bone show different stresses of 13MPa and 1 MPa, respectively, and exhibit complex high frequency responses. Observed results may offer insight into the wave interactions between the different materials comprising the calcaneus, such as impedance mismatch and refraction. Pore pressure in the marrow may be another important factor to consider in understanding stress propagation in the calcaneus.
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Reports on the topic "Fragmentation upon impact"

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Clausen, Jay, Samuel Beal, Thomas Georgian, Kevin Gardner, Thomas Douglas, and Ashley Mossell. Effects of milling on the metals analysis of soil samples containing metallic residues. Engineer Research and Development Center (U.S.), July 2021. http://dx.doi.org/10.21079/11681/41241.

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Metallic residues are distributed heterogeneously onto small-arms range soils from projectile fragmentation upon impact with a target or berm backstop. Incremental Sampling Methodology (ISM) can address the spatially heterogeneous contamination of surface soils on small-arms ranges, but representative kilogram-sized ISM subsamples are affected by the range of metallic residue particle sizes in the sample. This study compares the precision and concentrations of metals in a small-arms range soil sample processed by a puck mill, ring and puck mill, ball mill, and mortar and pestle prior to analysis. The ball mill, puck mill, and puck and ring mill produced acceptable relative standard deviations of less than 15% for the anthropogenic metals of interest (Lead (Pb), Antimony (Sb), Copper (Cu), and Zinc (Zn)), with the ball mill exhibiting the greatest precision for Pb, Cu, and Zn. Precision by mortar and pestle, without milling, was considerably higher (40% to >100%) for anthropogenic metals. Media anthropogenic metal concentrations varied by more than 40% between milling methods, with the greatest concentrations produced by the puck mill, followed by the puck and ring mill and then the ball mill. Metal concentrations were also dependent on milling time, with concentrations stabilizing for the puck mill by 300 s but still increasing for the ball mill over 20 h. Differences in metal concentrations were not directly related to the surface area of the milled sample. Overall, the tested milling methods were successful in producing reproducible data for soils containing metallic residues. However, the effects of milling type and time on concentrations require consideration in environmental investigations.
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You might also be interested in the extended bibliographies on the topic 'Fragmentation upon impact' for particular source types:
Journal articles
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