Modeling and Input Shaping Control of a Micro Coaxial Radio-Controlled Helicopter Carrying a Suspended Load

Christopher Adams,James Potter,William Singhose 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10

Helicopters are often used to transport supplies and equipment to hard-to-reach areas. When a load is carried via suspension cables below a helicopter, the load oscillates in response to helicopter motion and external disturbances, such as wind. This oscillation is dangerous and adversely affects control of the helicopter, especially when carrying heavy loads. To provide better control over the helicopter, one approach is to suppress the load swing dynamics using a command-filtering method called input shaping. This approach does not require real-time measurement or estimation of the load states. A simple model of a helicopter carrying a suspended load is developed and experimentally verified on a micro coaxial radio-controlled helicopter. In addition, the effectiveness of input shaping at eliminating suspended load oscillation is demonstrated on the helicopter. The proposed model may assist with the design of input-shaping controllers for a wide array of helicopters carrying suspended loads.

Dynamic effect of high-speed trains on simple bridge structures

Christoph Adam,Patrick Salcher 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.51 No.4

In this paper the overall dynamic response of simple railway bridges subjected to high-speed trains is investigated numerically based on the mechanical models of simply supported single-span andcontinuous two-span Bernoulli-Euler beams. Each axle of the train, which is composed of rail cars and passenger cars, is considered as moving concentrated load. Distance, magnitude, and maximum speed of the moving loads are adjusted to real high-speed trains and to load models according to Eurocode 1. Nondimensionalcharacteristic parameters of the train-bridge interaction system are identified. These parameters permit a spectral representation of the dynamic peak response. Response spectra assist the practicing engineers in evaluating the expected dynamic peak response in the design process of railway bridges without performing time-consuming time history analyses.

How Authoritarian Regimes Maintain Domain Consensus: North Korea's Information Strategies in the Kim Jong-un Era

Adam Cathcart,Christopher Green,Steven Denney 한국학중앙연구원 한국학중앙연구원 2014 THE REVIEW OF KOREAN STUDIES Vol.17 No.2

The North Korean government of Kim Jong-un is experiencing multiple simultaneous challenges to its legitimacy, but few could be more serious than the inflow and circulation of information in society. This paper uses three case studies to specifically examine how the North Korean state is responding to this danger by actively projecting narratives of transformation: “re-defectors,” sports, and Kim Jong-un’s court orchestra, the Moranbong Band. In every case, it becomes clear that the state is employing an active strategy, not only responding to negative external portrayals, but also trying to shape its own image both within and without its borders. In order to understand how the state interacts with the North Korean public, this paper employs Thomas Callaghy’s trifurcated “domain consensus” as a framework by which to sub-categorize Pyongyang’s approach: normative, utilitarian, and coercive. It focuses on the first of these types of consensus formation, the normative, by exploring the information strategies used by the Kim Jong-un government as it seeks to promote a revised Weberian “reciprocity of expectations” with the population.

The Interaction of Cognitive Interference, Standing Surface, and Fatigue on Lower Extremity Muscle Activity

Christopher M. Hill,Hunter DeBusk,Jeffrey D. Simpson,Brandon L. Miller,Adam C. Knight,John C. Garner,Chip Wade,Harish Chander 한국산업안전보건공단 산업안전보건연구원 2019 Safety and health at work Vol.10 No.3

Background: Performing cognitive tasks and muscular fatigue have been shown to increase muscle activity of the lower extremity during quiet standing. A common intervention to reduce muscular fatigue is to provide a softer shoe-surface interface. However, little is known regarding how muscle activity is affected by softer shoe-surface interfaces during static standing. The purpose of this study was to assess lower extremity muscular activity during erect standing on three different standing surfaces, before and after an acute workload and during cognitive tasks. Methods: Surface electromyography was collected on ankle dorsiflexors and plantarflexors, and knee flexors and extensors of fifteen male participants. Dependent electromyography variables of mean, peak, root mean square, and cocontraction index were calculated and analyzed with a 2×2×3 withinsubject repeated measures analysis of variance. Results: Pre-workload muscle activity did not differ between surfaces and cognitive task conditions. However, greater muscle activity during post-workload balance assessment was found, specifically during the cognitive task. Cognitive task errors did not differ between surface and workload. Conclusions: The cognitive task after workload increased lower extremity muscular activity compared to quite standing, irrespective of the surface condition, suggesting an increased demand was placed on the postural control system as the result of both fatigue and cognitive task.

Dynamic effect of high-speed trains on simple bridge structures

Adam, Christoph,Salcher, Patrick Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.51 No.4

In this paper the overall dynamic response of simple railway bridges subjected to high-speed trains is investigated numerically based on the mechanical models of simply supported single-span and continuous two-span Bernoulli-Euler beams. Each axle of the train, which is composed of rail cars and passenger cars, is considered as moving concentrated load. Distance, magnitude, and maximum speed of the moving loads are adjusted to real high-speed trains and to load models according to Eurocode 1. Non-dimensional characteristic parameters of the train-bridge interaction system are identified. These parameters permit a spectral representation of the dynamic peak response. Response spectra assist the practicing engineers in evaluating the expected dynamic peak response in the design process of railway bridges without performing time-consuming time history analyses.

Management of Adult Unruptured Brain Arteriovenous Malformations: An Updated Network Meta-Analysis

Dmytriw Adam A.,Ku Jerry,Ghozy Sherief,Grewal Sahibjot,Cancelliere Nicole M.,Azzam Ahmed Y.,Robert W. Regenhardt,Rabinov James D.,Christopher J. Stapleton,Patel Krunal,Patel Aman B.,Pereira Vitor Mend 대한신경중재치료의학회 2023 Neurointervention Vol.18 No.2

The management of unruptured brain arteriovenous malformations (ubAVMs) is a complex challenge to neurovascular practitioners. This meta-analysis aimed to identify the optimal management of ubAVMs comparing conservative management, embolization, radiosurgery, microsurgical resection, and multimodality. The search strategy was developed a priori according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We searched the Ovid Medline, Embase, Web of Science, and Cochrane Library databases to identify relevant papers. Using R version 4.1.1., a frequentist network meta-analysis was conducted to compare different management modalities for the ubAVMs. Overall, the conservative group had the lowest risk of rupture (P-score=0.77), and the lowest rate of complications was found in the conservative group (P-score=1). Among different interventions, the multimodality group had the highest rupture risk (P-score=0.34), the lowest overall complications (P-score=0.75), the best functional improvement (P-score=0.65), and the lowest overall mortality (P-score=0.8). However, multimodality treatment showed a significantly higher risk of rupture (odds ratio [OR]=2.13; 95% confidence interval [95% CI]=1.18–3.86) and overall complication rate (OR=5.56; 95% CI=3.37–9.15) compared to conservative management; nevertheless, there were no significant differences in overall mortality or functional independence when considered independently. Conservative management is associated with the lowest rupture risk and complication rate overall. A multimodal approach is the best option when considering mortality rates and functional improvement in the context of existing morbidity/symptoms. Microsurgery, embolization, and radiosurgery alone are similar to the natural history in terms of functional improvement and mortality, but have higher complication rates.

European Liver Transplant Registry: Achievements and Evolution within a 30-Year History

( Rene Adam Vincent Karam ),( Valerie Cailliez ),( Christophe Duvoux ) 대한간학회 2018 춘·추계 학술대회 (KASL) Vol.2018 No.1

Methods: Data from participating centers are collected on a voluntary basis at regular intervals using a two-part, standardized questionnaire designed by the ELTR Coordinating Committee to capture information on donors and recipients. Part 1 focuses on donor and recipient data, on technical aspects of liver transplantation and induction immunosuppression. Part 2 comprises questions on post-transplant mortality, graft failure and maintenance immunosuppression during patient follow-up. Audits of contributing centers are randomly performed each year to assess the quality of the data. The methods used to populate the registry and obtain the data have been described previously.1 The ELTR represents around 95% of all the LT procedures performed in Europe. It is in close connection with all the national and multi-national organ sharing organizations for the exchange and quality control of the data. Results: We analyzed the ELTR data within the period from January 1988 to December 2016 with 147,161 LT. Patient survival was 83% at 1 year (yr), 71% at 5 yrs, 61% at 10 yrs, and 41% at 20 yrs. Forty-six percent of deaths and 67% of re-LTs occur within the first year after LT. Cirrhosis was the most frequent indication (50%) followed by cancer (17%), cholestatic diseases (10%), acute hepatic failure (9%) and metabolic disease (6%). 10-yr patient survival was 59% for cirrhosis and for acute hepatic failure, and 50% for cancer (P < 0.001). In cirrhotic patients, 10-yr survival was better for primary biliary cirrhosis (71%) than for alcoholic or virus-related cirrhosis (58%)(P < 0.001). In viral cirrhosis patients, 10-yr survival of HBV patients was better than HCV (68% vs 52%, P < 0.01). 10-yr patient survival in pediatric recipients was 78%. Age influenced 10-yr survival in adults (66%: 18-45 yrs, 59%: 45-60 yrs, 49%: 60-70 yrs, 40% in septuagenarians) (P < 0.001). In recent years, alternatives to the full-size graft LT after brain death (FSDBD) represent more than 20% overall, and more than 70% in pediatric patients. The best 10-yr graft survival was obtained with living donors and split-liver grafts (61% and 58%, respectively), intermediate with reduced and Full-Size Donor Brain Death (DBD) grafts (54% and 53%, respectively), and the worst with Donor Cardiac Death (DCD) and domino grafts (47% and 44%, respectively). Recently, different new cold static preservation solutions have been increasingly used as alternative to the UW. 10-yr graft survival for the main solutions was 62% for UW, 61% for Celsior and IGL-1, and 55% for HTK. Accordingly, this latter solution has been independently associated to a risk of graft loss in a recent publication.2 Comments: The ELTR has become the reference to assess the outcome and evolution of LT in Europe. Along its 30-year history, it has contributed to better define the indications of LT, to report the results of living related LT, to assess the risk for the living donor, as well as to choose the best preservation solutions for the liver graft (2) and the type of immunosuppression.3 It represents a model of European scientific collaboration that gathers prospectively and analyses continuously more than 150,000 liver transplantations. With the analysis of this Big Data, ELTR provides valuable information not only to the professionals, but also to the patients.

Identification of a Systemic Lupus Erythematosus Susceptibility Locus at 11p13 between <i>PDHX</i> and <i>CD44</i> in a Multiethnic Study

Lessard, Christopher J.,Adrianto, Indra,Kelly, Jennifer A.,Kaufman, Kenneth M.,Grundahl, Kiely M.,Adler, Adam,Williams, Adrienne H.,Gallant, Caroline J.,Anaya, Juan-Manuel,Bae, Sang-Cheol,Boackle, Sus Elsevier 2011 American journal of human genetics Vol.88 No.1

<P>Systemic lupus erythematosus (SLE) is considered to be the prototypic autoimmune disease, with a complex genetic architecture influenced by environmental factors. We sought to replicate a putative association at 11p13 not yet exceeding genome-wide significance (p < 5 × 10<SUP>−8</SUP>) identified in a genome-wide association study (GWAS). Our GWA scan identified two intergenic SNPs located between <I>PDHX</I> and <I>CD44</I> showing suggestive evidence of association with SLE in cases of European descent (rs2732552, p = 0.004, odds ratio [OR] = 0.78; rs387619, p = 0.003, OR = 0.78). The replication cohort consisted of >15,000 subjects, including 3562 SLE cases and 3491 controls of European ancestry, 1527 cases and 1811 controls of African American (AA) descent, and 1265 cases and 1260 controls of Asian origin. We observed robust association at both rs2732552 (p = 9.03 × 10<SUP>−8</SUP>, OR = 0.83) and rs387619 (p = 7.7 × 10<SUP>−7</SUP>, OR = 0.83) in the European samples with p<SUB>meta</SUB> = 1.82 × 10<SUP>−9</SUP> for rs2732552. The AA and Asian SLE cases also demonstrated association at rs2732552 (p = 5 × 10<SUP>−3</SUP>, OR = 0.81 and p = 4.3 × 10<SUP>−4</SUP>, OR = 0.80, respectively). A meta-analysis of rs2732552 for all racial and ethnic groups studied produced p<SUB>meta</SUB> = 2.36 × 10<SUP>−13</SUP>. This locus contains multiple regulatory sites that could potentially affect expression and functions of <I>CD44</I>, a cell-surface glycoprotein influencing immunologic, inflammatory, and oncologic phenotypes, or PDHX, a subunit of the pyruvate dehydrogenase complex.</P>

The Interaction of Cognitive Interference, Standing Surface, and Fatigue on Lower Extremity Muscle Activity

Hill, Christopher M.,DeBusk, Hunter,Simpson, Jeffrey D.,Miller, Brandon L.,Knight, Adam C.,Garner, John C.,Wade, Chip,Chander, Harish Occupational Safety and Health Research Institute 2019 Safety and health at work Vol.10 No.3

Background: Performing cognitive tasks and muscular fatigue have been shown to increase muscle activity of the lower extremity during quiet standing. A common intervention to reduce muscular fatigue is to provide a softer shoe-surface interface. However, little is known regarding how muscle activity is affected by softer shoe-surface interfaces during static standing. The purpose of this study was to assess lower extremity muscular activity during erect standing on three different standing surfaces, before and after an acute workload and during cognitive tasks. Methods: Surface electromyography was collected on ankle dorsiflexors and plantarflexors, and knee flexors and extensors of fifteen male participants. Dependent electromyography variables of mean, peak, root mean square, and cocontraction index were calculated and analyzed with a $2{\times}2{\times}3$ within-subject repeated measures analysis of variance. Results: Pre-workload muscle activity did not differ between surfaces and cognitive task conditions. However, greater muscle activity during post-workload balance assessment was found, specifically during the cognitive task. Cognitive task errors did not differ between surface and workload. Conclusions: The cognitive task after workload increased lower extremity muscular activity compared to quite standing, irrespective of the surface condition, suggesting an increased demand was placed on the postural control system as the result of both fatigue and cognitive task.

Evaluation and analytical approximation of Tuned Mass Damper performance in an earthquake environment

Alexander Tributsch,Christoph Adam 국제구조공학회 2012 Smart Structures and Systems, An International Jou Vol.10 No.2

This paper aims at assessing the seismic performance of Tuned Mass Dampers (TMDs) based on sets of recorded ground motions. For the simplest configuration of a structure-TMD assembly, in a comprehensive study characteristic response quantities are derived and statistically evaluated. Optimal tuning of TMD parameters is discussed and evaluated. The response reduction by application of a TMD is quantified depending on the structural period, inherent damping of the stand-alone structure, and ratio of TMD mass to structural mass. The effect of detuning on the stroke of the TMD and on the structural response is assessed and quantified. It is verified that a TMD damping coefficient larger than the optimal one reduces the peak deflection of the TMD spring significantly, whereas the response reduction of the main structure remains almost unaffected. Analytical relations for quantifying the effect of a TMD are derived and subsequently evaluated. These relations allow the engineer in practice a fast and yet accurate assessment of the TMD performance.