Scholarly Articles
Permanent URI for this collection
To make your scholarly work available here, please see information about Duke’s open access policy and the submission process on the ScholarWorks web site.
Browse
Browsing Scholarly Articles by Type "Conference"
Now showing 1 - 20 of 54
Results Per Page
Sort Options
Item Open Access A Monopoly on Marcan Priority? Fallacies at the Heart of Q(Society of Biblical Literature Seminar Papers 2000, 2000) Goodacre, MSItem Open Access A Spatio-temporal Coupling Method to Reduce the Time-to-Solution of Cardiovascular Simulations(http://ieeexplore.ieee.org/abstract/document/6877292/, 2017-01-28) Randles, A; Kaxiras, EKWe present a new parallel-in-time method designed to reduce the overall time-to-solution of a patient-specific cardiovascular flow simulation. Using a modified Para real algorithm, our approach extends strong scalability beyond spatial parallelism with fully controllable accuracy and no decrease in stability. We discuss the coupling of spatial and temporal domain decompositions used in our implementation, and showcase the use of the method on a study of blood flow through the aorta. We observe an additional 40% reduction in overall wall clock time with no significant loss of accuracy, in agreement with a predictive performance model.Item Open Access ACL Loading And Jump Performance Are Decreased With Increased Knee Flexion Landing And Soft Landing(MEDICINE AND SCIENCE IN SPORTS AND EXERCISE, 2013-05) Dai, Boyi; Garrett, William E; Gross, Michael T; Padua, Darin A; Queen, Robin M; Yu, BingItem Open Access Acute Effects Of Gait Change During Simulated Pregnancy Using The Empathy Belly (R)(MEDICINE AND SCIENCE IN SPORTS AND EXERCISE, 2010-05) Butler, Robert J; Elpers, Melissa; Queen, Robin MItem Open Access Adaptability index: quantifying CT tube current modulation performance from dose and quality informatics(2017-03-17) Ria, F; Wilson, JM; Zhang, Y; Samei, EThe balance between risk and benefit in modern CT scanners is governed by the automatic adaptation mechanisms that adjust x-ray flux for accommodating patient size to achieve certain image noise values. The effectiveness of this adaptation is an important aspect of CT performance and should ideally be characterized in the context of real patient cases. Objective of this study was to characterize CT performance with an index that includes image-noise and radiation dose across a clinical patient population. The study included 1526 examinations performed by three scanners, from two vendors, used for two clinical protocols (abdominopelvic and chest). The dose-patient size and noise-patient size dependencies were linearized, and a 3D-fit was performed for each protocol and each scanner with a planar function. In the fit residual plots the Root Mean Square Error (RMSE) values were estimated as a metric of CT adaptability across the patient population. The RMSE values were between 0.0344 HU1/2 and 0.0215 HU1/2: different scanners offer varying degrees of reproducibility of noise and dose across the population. This analysis could be performed with phantoms, but phantom data would only provide information concerning specific exposure parameters for a scan: instead, a general population comparison is a way to obtain new information related to the relevant clinical adaptability of scanner models. A theoretical relationship between image noise, CTDIvol and patient size was determined based on real patient data. This relationship may provide a new index related to the scanners' adaptability concerning image quality and radiation dose across a patient population. © (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.Item Open Access An ocean sensor for measuring the seawater electrochemical response of 8 metals referenced to zinc, for determining ocean pH.(Proceedings of the International Conference on Sensing Technology, ICST, 2016-03-21) Brooke, MA; Cole, E; Dale, J; Prasad, A; Quach, H; Bau, R; Nowacek, D; Bhatt, E© 2015 IEEE.We describe the use of a multi-metal electrochemical cell for measuring ocean pH. The sensor was designed to be robust, inexpensive, and capable of 0.02 sensitivity to pH in the narrow ranges required for marine pH monitoring. A prototype sensor has undergone an extended ocean deployment with promising results.Item Open Access Attack-Resilient State Estimation in the Presence of NoisePajic, M; Tabuada, P.; Lee, I.; Pappas, G.J.We consider the problem of attack-resilient state estimation in the presence of noise. We focus on the most general model for sensor attacks where {any} signal can be injected via the compromised sensors. An $l_0$-based state estimator that can be formulated as a mixed-integer linear program and its convex relaxation based on the $l_1$ norm are presented. For both $l_0$ and $l_1$-based state estimators, we derive rigorous analytic bounds on the state-estimation errors. We show that the worst-case error is linear with the size of the noise, meaning that the attacker cannot exploit noise and modeling errors to introduce unbounded state-estimation errors. Finally, we show how the presented attack-resilient state estimators can be used for sound attack detection and identification, and provide conditions on the size of attack vectors that will ensure correct identification of compromised sensors.Item Open Access Automatic verification of linear controller software(2015 Proceedings of the International Conference on Embedded Software, EMSOFT 2015, 2015-11-04) Pajic, M; Park, J; Lee, I; Pappas, GJ; Sokolsky, O© 2015 IEEE.We consider the problem of verification of software implementations of linear time-invariant controllers. Commonly, different implementations use different representations of the controller's state, for example due to optimizations in a third-party code generator. To accommodate this variation, we exploit input-output controller specification captured by the controller's transfer function and show how to automatically verify correctness of C code controller implementations using a Frama-C/Why3/Z3 toolchain. Scalability of the approach is evaluated using randomly generated controller specifications of realistic size.Item Open Access BOLT: Energy-efficient out-of-order latency-tolerant execution(Proceedings - International Symposium on High-Performance Computer Architecture, 2010-05-27) Hilton, A; Roth, ALT (latency tolerant) execution is an attractive candidate technique for future out-of-order cores. LT defers the forward slices of LLC (last-level cache) misses to a slice buffer and re-executes them when the misses return. An LT core increases ILP without physically scaling the issue queue and register file and increases MLP without additional software threads that can reduce cache performance. Unfortunately, proposed LT designs are not energy ef.cient. They require too many additional structures and they defer and re-execute too many instructions to justify their performance gains. In this paper, we address these inefficiencies. We introduce a microarchitecture called BOLT (Better Out-of-Order Latency-Tolerance) that implements LT as an alternative use of SMT (Simultaneous Multi-Threading). We also present a new slice buffer organization and traversal scheme that increases performance and reduces overhead by pruning instances of useless and redundant LT. Collectively, these modifications turn out-of-order LT into a technique that improves performance in an energy-efficient way. ©2009 IEEE.Item Open Access Changes In Lower Extremity Mechanics During A Stop Jump From 6 To 12 Months Following ACL Reconstruction(MEDICINE AND SCIENCE IN SPORTS AND EXERCISE, 2013-05) Butler, Robert J; Dai, Boyi; Garrett, William E; Queen, Robin MItem Open Access “Connections” for developing cultural content in Korean language curriculum 한국어 교육과 문화 교수의 연계(The proceedings of the 25th International Conference on Korean Language Education, 2015) Kim, Hae-YoungItem Metadata only “Connections” for developing cultural content in Korean language curriculum 한국어 교육과 문화 교수의 연계(The proceedings of the 25th International Conference on Korean Language Education, 2015) Kim, HItem Open Access CPROB: Checkpoint processing with opportunistic minimal recovery(Parallel Architectures and Compilation Techniques - Conference Proceedings, PACT, 2009-11-23) Hilton, A; Eswaran, N; Roth, ACPR (Checkpoint Processing and Recovery) is a physical register management scheme that supports a larger instruction window and higher average IPC than conventional ROB-style register management. It does so by restricting mis-speculation recovery to checkpoints created at rename, and leveraging this restriction to aggressively reclaim registers that don't appear in checkpoints. The cost of CPR is checkpoint overhead, which is incurred when a mis-speculation occurs on an instruction for which a checkpoint was not created a priori. Here, CPR must recover to the immediately older checkpoint, squashing instructions older than the mis-speculation itself. In contrast, a ROB processor performs minimal recovery and only squashes instructions younger than the mis-speculation. CPROB is a hybrid register management scheme that preserves CPR's aggressive reclamation while opportunistically minimizing checkpoint overhead. CPROB extends CPR to track and hold the registers needed to perform minimal recovery to un-executed branches within each checkpoint. Recovery registers are held on a best-effort basis only. A checkpoint's recovery registers can be freed spontaneously when all branches in the checkpoint execute. They can also be aggressively victimized if dispatch needs registers to proceed. CPROB naturally adapts the register reclamation policy to dynamic branch behavior. When branch mis-predictions are infrequent and registers are needed to support a large window, CPROB victimizes registers and behaves like CPR. When mis-predictions are frequent and the window is small, CPROB holds on to registers and behaves like ROB. As a result, it out-performs both CPR and ROB for a given program. This performance improvement, combined with reduced checkpoint overhead, makes CPROB more energy-efficient than either ROB or CPR.Item Open Access CT Scan Dosimetric Parameters Routine Monitoring: First Results of Radiation Dose Optimization Strategies Promptly Provided by a Multidisciplinary Team(2015-11-29) Ria, F; Bergantin, A; Redaelli, I; Invernizzi, M; Vai, A; Fazzini, D; Gozzi, G; Papa, SCONCLUSION Radiation dose reduction, while saving image quality could be easily implemented with this approach. Furthermore, the availability of a dosimetric data archive provides immediate feedbacks, related to the implemented optimization strategies. Background JCI Standards and European Legislation (EURATOM 59/2013) require the implementation of patient radiation protection programs in diagnostic radiology. Aim of this study is to demonstrate the possibility to reduce patients radiation exposure without decreasing image quality, through a multidisciplinary team (MT), which analyzes dosimetric data of diagnostic examinations. Evaluation Data from CT examinations performed with two different scanners (Siemens DefinitionTM and GE LightSpeed UltraTM) between November and December 2013 are considered. CT scanners are configured to automatically send images to DoseWatch© software, which is able to store output parameters (e.g. kVp, mAs, pitch ) and exposure data (e.g. CTDIvol, DLP, SSDE). Data are analyzed and discussed by a MT composed by Medical Physicists and Radiologists, to identify protocols which show critical dosimetric values, then suggest possible improvement actions to be implemented. Furthermore, the large amount of data available allows to monitor diagnostic protocols currently in use and to identify different statistic populations for each of them. Discussion We identified critical values of average CTDIvol for head and facial bones examinations (respectively 61.8 mGy, 151 scans; 61.6 mGy, 72 scans), performed with the GE LightSpeed CTTM. Statistic analysis allowed us to identify the presence of two different populations for head scan, one of which was only 10% of the total number of scans and corresponded to lower exposure values. The MT adopted this protocol as standard. Moreover, the constant output parameters monitoring allowed us to identify unusual values in facial bones exams, due to changes during maintenance service, which the team promptly suggested to correct. This resulted in a substantial dose saving in CTDIvol average values of approximately 15% and 50% for head and facial bones exams, respectively. Diagnostic image quality was deemed suitable for clinical use by radiologists.Item Open Access Curation and preservation of complex data: North Carolina Geospatial Data Archiving Project(http://www.ils.unc.edu/digccurr2007/program.html) Tuttle, J; Morris, SThe North Carolina Geospatial Data Archiving Project (NCGDAP) is a three-year joint effort of the North Carolina State University Libraries and the North Carolina Center for Geographic Information and Analysis focused on collection and preservation of digital geospatial data resources from state and local government agencies. CGDAP is being undertaken in partnership with the Library of Congress under the ational Digital Information Infrastructure and Preservation Program (NDIIPP). “Digital geospatial data” consists of digital information that identifies the geographic location and characteristics of natural or constructed features and boundaries on the earth. Such data resources include geographic information systems (GIS) data sets, digitized maps, remote sensing data resources such as digital aerial photography, and tabular data that are tied to specific locations. These complex data objects do not suffer well from neglect, and long-term preservation will involve some combination of format migration and retention of critical documentation. While the main focus of NCGDAP is on organizational issues related to the engagement of spatial data infrastructure in the process of data archiving--with the demonstration repository seen more as a catalyst for discussion rather than an end in itself--this paper focuses more narrowly on the technical challenges associated with eveloping an ingest workflow and archive development process. New preservation hallenges associated with emergent content forms are also resented.Item Open Access Curation and preservation of complex data: North Carolina Geospatial Data Archiving ProjectMorris, S; Tuttle, JThe North Carolina Geospatial Data Archiving Project (NCGDAP) is a three-year joint effort of the North Carolina State University Libraries and the North Carolina Center for Geographic Information and Analysis focused on collection and preservation of digital geospatial data resources from state and local government agencies. NCGDAP is being undertaken in partnership with the Library of Congress under the National Digital Information Infrastructure and Preservation Program (NDIIPP). “Digital geospatial data” consists of digital information that identifies the geographic location and characteristics of natural or constructed features and boundaries on the earth. Such data resources include geographic information systems (GIS) data sets, digitized maps, remote sensing data resources such as digital aerial photography, and tabular data that are tied to specific locations. These complex data objects do not suffer well from neglect, and long-term preservation will involve some combination of format migration and retention of critical documentation. While the main focus of NCGDAP is on organizational issues related to the engagement of spatial data infrastructure in the process of data archiving--with the demonstration repository seen more as a catalyst for discussion rather than an end in itself--this paper focuses more narrowly on the technical challenges associated with developing an ingest workflow and archive development process. New preservation challenges associated with emergent content forms are also presented.Item Open Access Decoupled store completion/silent deterministic replay: Enabling scalable data memory for CPR/CFP processors(Proceedings - International Symposium on Computer Architecture, 2009-11-30) Hilton, A; Roth, ACPR/CFP (Checkpoint Processing and Recovery/Continual Flow Pipeline) support an adaptive instruction window that scales to tolerate last-level cache misses. CPR/CFP scale the register file by aggressively reclaiming the destination registers of many in-flight instructions. However, an analogous mechanism does not exist for stores and loads. As the window expands, CPR/CFP processors must track all in-flight stores and loads to support forwarding and detect memory ordering violations. The previously-described SVW (Store Vulnerability Window) and SQIP (Store Queue Index Prediction) schemes provide scalable, non-associative load and store queues, respectively. However, they don't work smoothly in a CPR/CFP context. SVW/SQIP rely on the ability to dynamically stall some loads until a specific older store writes to the cache. Enforcing this serialization in CPR/CFP is expensive if the load and store are in the same checkpoint. We introduce two complementary procedures that implement this serialization efficiently. Decoupled Store Completion (DSC) allows stores to write to the cache before the enclosing checkpoint completes execution. Silent Deterministic Replay (SDR) supports mis-speculation recovery in the presence of DSC by replaying loads older than completed stores using values from the load queue. The combination of DSC and SDR enables an SVW/SQIP based CPR/CFP memory system that outperforms previous designs while occupying less area. Copyright 2009 ACM.Item Open Access Design methodologies for securing cyber-physical systems(2015 International Conference on Hardware/Software Codesign and System Synthesis, CODES+ISSS 2015, 2015-11-17) Faruque, MAA; Regazzoni, F; Pajic, M© 2015 IEEE.Cyber-Physical Systems (CPS) are in most cases safety- and mission-critical. Standard design techniques used for securing embedded systems are not suitable for CPS due to the restricted computation and communication budget available in the latter. In addition, the sensitivity of sensed data and the presence of actuation components further increase the security requirements of CPS. To address these issues, it is necessary to provide new design methods in which security is considered from the beginning of the whole design flow and addressed in a holistic way. In this paper, we focus on the design of secure CPS as part of the complete CPS design process, and provide insights into new requirements on platform-aware design of control components, design methodologies and architectures posed by CPS design. We start by discussing methods for the multi-disciplinary modeling, simulation, tools, and software synthesis challenges for CPS. We also present a framework for design of secure control systems for CPS, while taking into account properties of the underlying computation and communication platforms. Finally, we describe the security challenges in the computing hardware that is used in CPS.Item Open Access Does the degree of coarctation of the aorta influence wall shear stress focal heterogeneity?(Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS, 2016-10-13) Gounley, J; Chaudhury, R; Vardhan, M; Driscoll, M; Pathangey, G; Winarta, K; Ryan, J; Frakes, D; Randles, A© 2016 IEEE.The development of atherosclerosis in the aorta is associated with low and oscillatory wall shear stress for normal patients. Moreover, localized differences in wall shear stress heterogeneity have been correlated with the presence of complex plaques in the descending aorta. While it is known that coarctation of the aorta can influence indices of wall shear stress, it is unclear how the degree of narrowing influences resulting patterns. We hypothesized that the degree of coarctation would have a strong influence on focal heterogeneity of wall shear stress. To test this hypothesis, we modeled the fluid dynamics in a patient-specific aorta with varied degrees of coarctation. We first validated a massively parallel computational model against experimental results for the patient geometry and then evaluated local shear stress patterns for a range of degrees of coarctation. Wall shear stress patterns at two cross sectional slices prone to develop atherosclerotic plaques were evaluated. Levels at different focal regions were compared to the conventional measure of average circumferential shear stress to enable localized quantification of coarctation-induced shear stress alteration. We find that the coarctation degree causes highly heterogeneous changes in wall shear stress.Item Metadata only Duke Research in Perspective: Trend of publications and interdisciplinarity of Duke's education and research(2018-01-29) Abed Zadeh, A; Hagh, Varda FWe investigate the trends in interdisciplinary research at Duke University using datasets provided by Scholars@Duke and The Graduate School. The data holds bibliographical information on faculty appointments, their publications (including abstracts and publication venues ), and faculty members of PhD dissertation committees for students completing their PhD degrees from 2012 to 2017. By looking at the total number of publications at Duke, we observe a descending trend over the course of five years in all schools except Duke Law School. We then look at the fraction of these publications that cross departmental and school boundaries. The results depict fluctuations over time in most cases; however some meaningful trends in the interdisciplinary research are observed . For instance, Institutes and Provost’s Academic Units , and Trinity College of Arts and Sciences have been showing an increase in the fraction of interdisciplinary publications despite the decrease in their total number of published papers. To see the overlap between schools, we look at the graphs of coauthorships between different organization/departments, and how PhD students in each department select their dissertation committee members from different schools. The School of Medicine , and Trinity College of Arts and Sciences are the leading schools with the largest number of publications and collaborations. By looking at these graphs we can see that School of Medicine has done an incredible job at crossing the boundaries and collaborating with almost all the other schools across Duke. The same two schools have the largest number of faculty who serve as dissertation committee members in all schools and departments across Duke.
- «
- 1 (current)
- 2
- 3
- »