John C. Steuben, Athanasios Iliopoulos, John G. Michopoulos,
A critical element for the design, characterization, and certification of materials and products produced by additive manufacturing processes is the ability to accurately and efficiently model the associated materials and processes. This is necessary for tailoring these processes to endow the associated products with proper geometrical and functional features. In an effort to address these needs in a computationally elegant and at the same time physically realistic manner, this paper presents the ...
Tópico(s): Granular flow and fluidized beds
2016 - Elsevier BV | Computer Methods in Applied Mechanics and Engineering
John C. Steuben, Athanasios Iliopoulos, John G. Michopoulos,
Tópico(s): Additive Manufacturing Materials and Processes
2016 - Elsevier BV | Computer-Aided Design
John G. Michopoulos, Athanasios Iliopoulos, John C. Steuben, Andrew J. Birnbaum, Samuel G. Lambrakos,
In order to establish modeling and simulation (M&S) in support of Additive Manufacturing Processes (AMP) control for tailoring functional component performance by design, a methodology is introduced for identifying relevant M&S challenges. This exercise is meant to spur research addressing the specific issue of tailoring functional component performance by design, as well as AMP-related process optimization more generally. A composition abstraction that connects process control with functional performance ...
Tópico(s): Injection Molding Process and Properties
2018 - Elsevier BV | Additive manufacturing
Andrew J. Birnbaum, John C. Steuben, Erin Barrick, Athanasios Iliopoulos, John G. Michopoulos,
The observation of sub-grained cellular features in additively manufactured (AM)/selectively laser melted (SLM) 316L stainless steel components has remained an interesting, though incompletely understood phenomenon. However, the recently observed correlation linking the presence of these features with significantly enhanced mechanical strength in SLM 316L materials has driven a renewed interest and effort toward elucidating the mechanism(s) by which they are formed. To date, the dominant hypothesis, ...
Tópico(s): High Entropy Alloys Studies
2019 - Elsevier BV | Additive manufacturing
Monique Radman, Christopher W. Mastropietro, John M. Costello, Venugopal Amula, Saúl Flores, Elizabeth Caudill, Karan Karki, Karl Migally, Sukumar Suguna Narasimhulu, Kurt D. Piggott, Peter Sassalos, Michael Wilhelm, Elizabeth A. S. Moser, Katherine Cashen, Aditya Badheka, Adnan Bakar, Jason R. Buckley, Saurabh Chiwane, Margaret Gray, Ilias Iliopoulos, John F. Lucas, David M. Kwiatowski, Keshava Murthy Narayana Gowda, Christine M. Riley, Jennifer Smerling,
Tópico(s): Cardiovascular Issues in Pregnancy
2020 - Elsevier BV | The Annals of Thoracic Surgery
Athanasios Iliopoulos, John G. Michopoulos, N. P. Andrianopoulos,
Abstract: In responding to the needs of the material characterization community, the recently developed mesh‐free random grid method (MFRGM) has been exhibiting very promising characteristics of accuracy, adaptability, implementation flexibility and efficiency. To address the design specification of the method according to an intended application, we are presenting a sensitivity analysis that aids into determining the effects of the experimental and computational parameters characterizing the MFRGM ...
Tópico(s): Infrastructure Maintenance and Monitoring
2010 - Wiley | Strain
Hazim J. Safi, Kenneth R. Hess, Mark Randel, Dimitrios Iliopoulos, John C. Baldwin, Ravi K. Mootha, Salwa S. Shenaq, Roy Sheinbaum, Thomas L. Greene,
Purpose: This study was conducted to evaluate the role of cerebrospinal fluid (CSF) drainage and distal aortic perfusion (DAP) in the prevention of postoperative neurologic complications for high-risk patients who had undergone type I and type II thoracoabdominal aortic aneurysm (TAAA) repair.Methods: CSF drainage and DAP were used as an adjunct in the treatment of 94 patients with TAAA (31 type I, 63 type II) between September 1992 and December 1994; 67 were men and 27 were women. The median age was ...
Tópico(s): Cardiac, Anesthesia and Surgical Outcomes
1996 - Elsevier BV | Journal of Vascular Surgery
Matthew Malone, Namson S. Lau, Jessica M. White, Antonín Novák, Wei Xuan, Jim Iliopoulos, John A. Crozier, H G Dickson,
To determine the impact of diabetes mellitus (DM) and other comorbidities on length of stay (LOS) and costs in patients with peripheral arterial disease (PAD) admitted to a vascular surgical unit.A retrospective study was conducted between January 2011 and July 2012 at a tertiary referral hospital in Sydney. Demographic, laboratory, and operative data were obtained from the Australasian Vascular Audit database and hospital diagnostic-related group (DRG) reports. Patients with confirmed PAD with or without ...
Tópico(s): Antiplatelet Therapy and Cardiovascular Diseases
2014 - Elsevier BV | European Journal of Vascular and Endovascular Surgery
Nena Galanidou, James Cole, George Iliopoulos, John McNabb,
This paper introduces a new inter-disciplinary and international research project focused on the Palaeolithic site of Rodafnidia on the Greek island of Lesvos, located in the north-eastern Aegean Sea (Figure 1). Rodafnidia, near the village of Lisvori, is less than a kilometre away from the south-western shore of the large Kalloni Gulf. It is a prolific open-air site spanning the Lower and Middle Palaeolithic. What makes this site unique is the richness of its Acheulean lithic assemblage which, so ...
Tópico(s): Marine and environmental studies
2013 - Cambridge University Press | Antiquity
Athanasios Iliopoulos, John G. Michopoulos,
SUMMARY Full‐field strain measurement techniques are based on computing the spatial derivatives of numerical or functional approximations of the underlying displacement fields extracted from digital imaging methods. These methods implicitly assume that the medium satisfies the strain compatibility conditions, which are only true in the case of a continuum body that remains continuum throughout its deformation history. In the present work, we introduce a method that can be used to calculate the strain ...
Tópico(s): Ultrasonics and Acoustic Wave Propagation
2013 - Wiley | International Journal for Numerical Methods in Engineering
Hazim J. Safi, Charles C. Miller, Mahesh H. Subramaniam, Matthew P. Campbell, Dimitrios Iliopoulos, John J. O’Donnell, Michael J. Reardon, George V. Letsou, Rafael Espada,
Purpose: Although some authors advocate hypothermic circulatory arrest for spinal cord protection in descending thoracic and thoracoabdominal repair, this method has been associated with high morbidity and mortality rates in other studies. The safety and effectiveness of this surgical adjunct were evaluated. Methods: Between February 1991 and April 1997, 409 patients underwent thoracic or thoracoabdominal aortic repair. Because of an inability to gain proximal aortic control because of anatomic ...
Tópico(s): Cardiac Valve Diseases and Treatments
1998 - Elsevier BV | Journal of Vascular Surgery
Athanasios Iliopoulos, John C. Steuben, Tanner Kirk, Theocharis Baxevanis, John G. Michopoulos, Dimitris C. Lagoudas,
Emerging applications of shape memory alloys (SMAs) functioning as actuators in areas such as the aeronautic and automotive industries, require better understanding of their failure mechanisms and mechanics under combined thermomechanical loading. In this paper we examine the thermomechanically–assisted fracture of double notched NiTi coupons during thermal cycling sweeps under isobaric loading conditions. This loading path is an idealization of typical loading paths that utilize these alloys as ...
Tópico(s): Shape Memory Alloy Transformations
2017 - Elsevier BV | International Journal of Solids and Structures
R. Jones, R.K. Singh Raman, Athanasios Iliopoulos, John G. Michopoulos, Nam Phan, Daren Peng,
Tópico(s): Manufacturing Process and Optimization
2019 - Elsevier BV | International Journal of Fatigue
R. Jones, Calvin Rans, Athanasios Iliopoulos, John G. Michopoulos, Nam Phan, Daren Peng,
The United States Air Force (USAF) Guidelines for the Durability and Damage Tolerance (DADT) certification of Additive Manufactured (AM) parts states that the most difficult challenge for the certification of an AM part is to establish an accurate prediction of its DADT. How to address this challenge is the focus of the present paper. To this end this paper examines the variability in crack growth in tests on additively manufactured (AM) Ti-6Al-4V specimens built using selective layer melting (SLM). ...
Tópico(s): Manufacturing Process and Optimization
2021 - Multidisciplinary Digital Publishing Institute | Materials
Robert N. Saunders, A. L. K. Rawlings, Andrew J. Birnbaum, Athanasios Iliopoulos, John G. Michopoulos, Dimitris C. Lagoudas, Alaa Elwany,
Tópico(s): Manufacturing Process and Optimization
2022 - Springer Nature | Integrating materials and manufacturing innovation
Kirubel Teferra, X. Gary Tan, Athanasios Iliopoulos, John G. Michopoulos, Muhammad A. Qidwai,
Abstract A methodology is introduced to investigate the effect of intersubject head morphological variability on the mechanical response of the brain when subjected to blast overpressure loading. Nonrigid image registration techniques are leveraged to warp a manually segmented template model to an arbitrary number of subjects following a procedure to coarsely segment the subjects in batch. Finite element meshes are autogenerated, and blast analysis is conducted. The template model is initially constructed ...
Tópico(s): Traumatic Brain Injury and Neurovascular Disturbances
2018 - Wiley | International Journal for Numerical Methods in Biomedical Engineering
Tópico(s): Earth Systems and Cosmic Evolution
1985 - Springer Nature | NATO ASI series. Series B : Physics
... the correct direction.At the time Sheldon Glashow, John Iliopoulos, and Luciano Maiani developed the GIM mechanism, the ...
Tópico(s): Black Holes and Theoretical Physics
2006 - AIP Publishing | Physics Today
Andrew J. Birnbaum, Carl V. Thompson, John C. Steuben, Athanasios Iliopoulos, John G. Michopoulos,
Thin film crystallites typically exhibit normal or abnormal growth with maximum grain size limited by energetic and geometric constraints. Although epitaxial methods have been used to produce large single crystal regions, they impose limitations that preclude some compelling applications. The generation of giant grain thin film materials has broad implications for fundamental property analysis and applications. This work details the production of giant grains in Ag films (2.5 μm-thick), ranging in ...
Tópico(s): Copper Interconnects and Reliability
2017 - American Institute of Physics | Applied Physics Letters
Elias Sanidas, Charalampos Grassos, Dimitrios Papadopoulos, Maria Velliou, Kostas Tsioufis, Marina Mantzourani, Δέσποινα Περρέα, Dimitrios Iliopoulos, John Barbetseas, Vasilios Papademetriou,
Tópico(s): Hemodynamic Monitoring and Therapy
2019 - Springer Nature | Journal of Human Hypertension
John C. Steuben, Athanasios Iliopoulos, John G. Michopoulos,
The precise control of mass and energy deposition associated with additive manufacturing (AM) processes enables the topological specification and realization of how space can be filled by material in multiple scales. Consequently, AM can be pursued in a manner that is optimized such that fabricated objects can best realize performance specifications. In the present work, we propose a computational multiscale method that utilizes the unique meso-scale structuring capabilities of implicit slicers for ...
Tópico(s): Additive Manufacturing and 3D Printing Technologies
2018 - ASM International | Journal of Computing and Information Science in Engineering
Athanasios Iliopoulos, John C. Steuben, John G. Michopoulos,
The mechanical properties of the glass-epoxy composite material known as “G-10,” which is primarily used for electrical insulation purposes in electromechanical systems, have long been a topic of uncertainty and controversy. In the present paper, we demonstrate the application of an experimental methodology that exploits the Direct Strain Imaging (DSI) full field method to fully assess the elastic anisotropic mechanical properties of G-10. Tension and compression experiments were conducted for three ...
Tópico(s): Advanced Surface Polishing Techniques
2015 - Elsevier BV | Polymer Testing
John C. Steuben, Andrew J. Birnbaum, Athanasios Iliopoulos, John G. Michopoulos,
Additive manufacturing (AM) enables the fabrication of objects using successive additions of mass and energy. In this paper, we explore the use of analytic solutions to model the thermal aspects of AM, in an effort to achieve high computational performance and enable “in the loop” use for feedback control of AM processes. It is shown that the utility of existing analytical solutions is limited due to their underlying assumption of a homogeneous semi-infinite domain. These solutions must, therefore, ...
Tópico(s): Manufacturing Process and Optimization
2018 - ASM International | Journal of Computing and Information Science in Engineering
Underlying Foucault’s accounts of asylums, hospitals, prisons, and schools was a continuing concern with power and knowledge. In the field of mental health, his preoccupation with power relations and the construction of narratives of exclusion and repression in the History of Madness have led many scholars to consider Foucault an anti-psychiatrist (Freeman 1967; Laing 1967; Leach 1967; Shorter 1997, 274). They question the book’s historical data, which prioritize power relations and political analysis ...
Tópico(s): Historical Psychiatry and Medical Practices
2012 - Johns Hopkins University Press | Philosophy, psychiatry & psychology
Elias Sanidas, K. Tsakalis, Dimitrios Papadopoulos, Kanella Zerva, Maria Velliou, Δέσποινα Περρέα, Marina Mantzourani, Dimitrios Iliopoulos, John Barbetseas,
Masked hypertension (HTN) and white coat hypertension represent two reverse forms of clinical HTN with questionable prognostic significance. Recent evidence supports that low apelin and relaxin plasma levels contribute to vascular damage accelerating atherogenesis and predisposing to HTN and cardiovascular (CV) events. The aim of this study was to compare apelin and relaxin plasma levels between patients with masked hypertension (MH) and those with white coat HTN (WCH). Overall, 130 patients not receiving ...
Tópico(s): Cardiovascular Health and Disease Prevention
2018 - Wiley | Journal of Clinical Hypertension
John I. Iliopoulos, Michael J. Zdon, Brian G. Crawford, George E. Pierce, James H. Thomas, Arlo S. Hermreck,
Moderate renal dysfunction due to renal microembolization developed in eight patients who underwent abdominal aortic reconstruction for aneurysmal or occlusive disease. In each patient, the aorta around the renal arteries was thrombus-lined or severely ulcerated and was therefore the source of embolization, and aortic clamping near the renal arteries was required and provided the mechanism for embolization. Renal failure was moderate and did not require dialysis. Renal dysfunction appeared to be ...
Tópico(s): Aortic aneurysm repair treatments
1983 - Elsevier BV | The American Journal of Surgery
James H. Thomas, Brian L. McCroskey, John I. Iliopoulos, Creighton A. Hardin, Arlo S. Hermreck, George E. Pierce,
Tópico(s): Aortic Disease and Treatment Approaches
1983 - Elsevier BV | The American Journal of Surgery
James H. Thomas, Carol S. Connor, George E. Pierce, Richard I. MacArthur, John I. Iliopoulos, Arlo S. Hermreck,
To evaluate the effect of levels of serum bilirubin on morbidity and mortality after pancreatoduodenectomy, a prospective study was designed to compare patients who underwent preoperative biliary decompression to those who did not. Preoperative biliary decompression decreased the mean serum bilirubin level from 15.8 to 5.8 mg/dl in one group of 10 patients (Group A). The only statistical differences between this group and the two other groups of patients (Groups B and C) who were not treated with ...
Tópico(s): Gallbladder and Bile Duct Disorders
1984 - Elsevier BV | The American Journal of Surgery
John I. Iliopoulos, George E. Pierce, Arlo S. Hermreck, Chris C. Haller, James H. Thomas,
The purpose of this study was to determine the significance of collateral supply from the hypogastric arteries (HGAs) to the inferior mesenteric arterial (IMA) bed. Peak systolic "stump" IMA and radial arterial pressures were obtained before and after clamping the right HGA, the left HGA, both HGAs, the middle colic artery (MCA) only, or the MCA plus right HGA, MCA plus left HGA, and MCA plus both HGAs in patients with aortoiliac aneurysm or occlusive disease. Six patients (four with aneurysms and two ...
Tópico(s): Abdominal Surgery and Complications
1990 - Elsevier BV | Journal of Vascular Surgery
John I. Iliopoulos, Paul E. Howanitz, George E. Pierce, Simon M. Kueshkerian, James H. Thomas, Arlo S. Hermreck,
Abstract Eleven patients had ischemic complications secondary to ligation, hypoperfusion, exclusion, or thrombosis of the hypogastric arteries after aortoiliac reconstruction or spontaneous aortoiliac thrombosis. Ligation of one hypogastric artery resulted in persistent ipsilateral buttock claudication in three patients. Bilateral acute hypogastric artery ischemia occurred in eight patients and resulted in paralysis in all eight patients, buttock necrosis in four patients, anal and bladder sphincteric dysfunction ...
Tópico(s): Thyroid and Parathyroid Surgery
1987 - Elsevier BV | The American Journal of Surgery