Examining the Effects of Scale, Mass Ratios and Column Shapes on the Vortex Induced Motion Response of a Semisubmersible Through CFD Analyses

2014 ◽  
Author(s):  
Oriol Rijken
Keyword(s):  
Model Tests ◽  
Data Sets ◽  
Mass Ratio ◽  
Pressure Data ◽  
Cross Sectional ◽  
Physical Experiments ◽  
Induced Motion ◽  
Cfd Analyses ◽  
Individual Column ◽  
Phase Relationships

The phenomenon of vortex induced motions (VIM) of a semisubmersible has been observed in the field and in model tests. The VIM response can be onerous to the fatigue live of SCR’s that are supported from the semisubmersible. Field observations indicate significantly smaller VIM amplitude than what present day model tests predict. The Scruton number is a parameter which affects the magnitude of the VIM response; the Scruton number includes the effect of mass ratio and damping. The effect of damping on VIM response has been examined in model test scale, and this analysis indicated that damping has a minimal effect on the VIM response amplitudes. The effect of the mass ratio and the effect of performing physical experiments at model scale are examined through CFD analyses. The objectives of the CFD analyses are to focus on the VIM phenomenon itself and to compare response magnitudes, while giving less importance to semisubmersible hull details and absolute response magnitudes. Hence, most of the CFD work is done in a 2D environment. Responses for various column cross-sectional shapes are examined; the column cross-sectional shapes include square, rectangular and five-sided. The VIM response is the result of pressures acting on the semisubmersible columns. The CFD analyses provide means to obtain the pressures at various locations at the various columns, and therefore can be used as a way to describe the phenomenon. These pressure data sets are evaluated to show where the majority of the excitation occurs and phase relationships between excitation forces acting on each individual column are presented.

Delivering Sustainable Water Systems Using Kalman Filter and Statistical Approach

2017 ◽  
Vol 4 (1) ◽  
pp. 41-52
Author(s):  
Dedy Loebis
Keyword(s):  
Kalman Filtering ◽  
Statistical Approach ◽  
Water Systems ◽  
Data Sets ◽  
Pressure Data ◽  
Burst Event ◽  
Sample Data ◽  
Other Information ◽  
Supply Systems ◽  
Frequency Features

This paper presents the results of work undertaken to develop and test contrasting data analysis approaches for the detection of bursts/leaks and other anomalies within wate r supply systems at district meter area (DMA)level. This was conducted for Yorkshire Water (YW) sample data sets from the Harrogate and Dales (H&D), Yorkshire, United Kingdom water supply network as part of Project NEPTUNE EP/E003192/1 ). A data analysissystem based on Kalman filtering and statistical approach has been developed. The system has been applied to the analysis of flow and pressure data. The system was proved for one dataset case and have shown the ability to detect anomalies in flow and pres sure patterns, by correlating with other information. It will be shown that the Kalman/statistical approach is a promising approach at detecting subtle changes and higher frequency features, it has the potential to identify precursor features and smaller l eaks and hence could be useful for monitoring the development of leaks, prior to a large volume burst event.

scholarly journals Trends in the prevalence of anaemia in Japanese adult women, 1989–2003

2008 ◽  
Vol 11 (3) ◽  
pp. 252-257 ◽  
Author(s):  
Fumi Hayashi ◽  
Nobuo Yoshiike ◽  
Katsushi Yoshita ◽  
Kazuo Kawahara
Keyword(s):  
Age Groups ◽  
Data Sets ◽  
Adult Women ◽  
Residential Areas ◽  
Nutrition Survey ◽  
Japanese Adult ◽  
Cross Sectional ◽  
Health And Nutrition ◽  
Trend Data ◽  
National Trends

AbstractObjectiveThere is an increasing concern of anaemia in Japanese women, but no national trend data has existed to date. We analysed long-term national trends of anaemia in adult women.DesignSecondary analyses of 15 consecutive cross-sectional nationwide surveys conducted during the period 1989–2003. Analyses were based on 5-year intervals (1989–1993, 1994–1998, 1999–2003).SettingJapan.SubjectsThe subjects included the National Health and Nutrition Survey of Japan (NHNS-J) population. Analyses were based on 50 967 non-pregnant/non-lactating women aged 20 years and over, with complete data sets. We stratified subjects into six age groups (20–29 years, 30–39 years, 40–49 years, 50–59 years, 60–69 years and 70+ years), and three age groups (20–49 years, 50–69 years, 70+ years) for analyses on residential areas (metropolitan, cities and towns).ResultsDecreases in trends of mean haemoglobin values (intravenous) were significant in all age groups. Changes in the prevalence of anaemia were significant only in women aged 30–39 and 40–49 years. Anaemia (haemoglobin < 12.0 g dl−1) increased from 16.8% to 20.6% in women aged 30–39 years, and from 20.2% to 26.9% in women aged 40–49 years, respectively. Prevalence was highest in women aged 70 years and older in all times, but no significant change was observed.ConclusionsHaemoglobin values have declined significantly in all ages in the last 15 years. Anaemia was especially significant in women aged 30–39 years and 40–49 years. Our findings suggest that a large number of young women in Japan are at risk of anaemia, so continuous monitoring and controlling efforts of this trend are needed.

scholarly journals Creation of the WHO Indicators of Infant and Young Child Development (IYCD): metadata synthesis across 10 countries

2018 ◽  
Vol 3 (5) ◽  
pp. e000747 ◽  
Author(s):  
Gillian A Lancaster ◽  
Gareth McCray ◽  
Patricia Kariger ◽  
Tarun Dua ◽  
Andrew Titman ◽  
...  
Keyword(s):  
Child Development ◽  
Developmental Trajectories ◽  
Receptive Language ◽  
Early Years ◽  
Fine Motor ◽  
Response Analysis ◽  
Data Sets ◽  
Cross Sectional ◽  
Low Middle Income Countries ◽  
Common Scale

BackgroundRenewed global commitment to the improvement of early child development outcomes, as evidenced by the focus of the United Nations Sustainable Development Goal 4, highlights an increased need for reliable and valid measures to evaluate preventive and interventional efforts designed to affect change. Our objective was to create a new tool, applicable across multicultures, to measure development from 0 to 3 years through metadata synthesis.MethodsFourteen cross-sectional data sets were contributed on 21 083 children from 10 low/middle-income countries (LMIC), assessed using seven different tools (caregiver reported or directly assessed). Item groups, measuring similar developmental skills, were identified by item mapping across tools. Logistic regression curves displayed developmental trajectories for item groups across countries and age. Following expert consensus to identify well-performing items across developmental domains, a second mapping exercise was conducted to fill any gaps across the age range. The first version of the tool was constructed. Item response analysis validated our approach by putting all data sets onto a common scale.Results789 individual items were identified across tools in the first mapping and 129 item groups selected for analysis. 70 item groups were then selected through consensus, based on statistical performance and perceived importance, with a further 50 items identified at second mapping. A tool comprising 120 items (23 fine motor, 23 gross motor, 20 receptive language, 24 expressive language, 30 socioemotional) was created. The linked data sets on a common scale showed a curvilinear trajectory of child development, highlighting the validity of our approach through excellent coverage by age and consistency of measurement across contributed tools, a novel finding in itself.ConclusionsWe have created the first version of a prototype tool for measuring children in the early years, developed using novel easy to apply methodology; now it needs to be feasibility tested and piloted across several LMICs.

scholarly journals Examination of the relationship between management and clinician agreement on communication openness, teamwork, and patient satisfaction in the US hospitals

2016 ◽  
Vol 5 (4) ◽  
pp. 20
Author(s):  
Olena Mazurenko ◽  
Jason Richter ◽  
Abby Swanson-Kazley ◽  
Eric Ford
Keyword(s):  
Patient Safety ◽  
Patient Satisfaction ◽  
Safety Culture ◽  
Healthcare Providers ◽  
Patient Safety Culture ◽  
Data Sets ◽  
Cross Sectional ◽  
Communication Openness ◽  
Cross Sectional Design ◽  
Willingness To Recommend

Background: Patient satisfaction has always been an area of focus for hospitals, but gained particular importance due to the changes in the Centers for Medicare and Medicaid reimbursement policies. Hospital managers and clinicians interact with patients in different ways and have different perspectives on safety culture, yet little is known about how that impacts patient satisfaction.Objective: To examine how the agreement between clinicians and management perspectives on patient safety culture is related to patient satisfaction by employing cross-sectional design with linear regressions.Methods: Two data sets were used: 2012 Hospital Survey on Patient Safety Culture and 2012 Hospital Consumer Assessment of Healthcare Providers and Systems (HCAHPS). The dependent variables were: overall rating of the hospital experience and willingness to recommend a hospital. The independent variables were four safety culture domains: communication openness, feedback, and communication about errors, teamwork within units, and teamwork between units.Results: The results suggest that manager and clinician agreement on high levels of communication openness, feedback and communication about errors, teamwork between units, and teamwork across units were positively and significantly associated with overall patient satisfaction and willingness to recommend. Additionally, more favorable perceptions about patient safety culture by only clinicians yielded similar findings.Conclusions: For policymakers, measuring managers and clinicians’ perceptions on patient safety culture may provide a valuable indicator of patient satisfaction throughout the country. While managers are more likely to have the power to devote resources to patient safety initiatives, they may not adequately judge culture in their unit and should take into account the perspectives of clinicians who have a more frontline perspective.

Relationship between fat-to-fat-free mass ratio and decrements in leg strength after downhill running

2001 ◽  
Vol 90 (4) ◽  
pp. 1334-1341 ◽  
Author(s):  
R. C. Hickner ◽  
P. M. Mehta ◽  
D. Dyck ◽  
P. Devita ◽  
J. A. Houmard ◽  
...  
Keyword(s):  
Body Mass ◽  
Muscle Glycogen ◽  
Linear Regression Analysis ◽  
Multiple Linear Regression Analysis ◽  
Fat Free Mass ◽  
Mass Ratio ◽  
Low Fat ◽  
Cross Sectional ◽  
Leg Strength ◽  
Downhill Running

The purpose of this study was to determine whether greater body fat mass (FM) relative to lean mass would result in more severe muscle damage and greater decrements in leg strength after downhill running. The relationship between the FM-to-fat-free mass ratio (FM/FFM) and the strength decline resulting from downhill running (−11% grade) was investigated in 24 male runners [age 23.4 ± 0.7 (SE) yr]. The runners were divided into two groups on the basis of FM/FFM: low fat (FM/FFM = 0.100 ± 0.008, body mass = 68.4 ± 1.3 kg) and normal fat (FM/FFM = 0.233 ± 0.020, body mass = 76.5 ± 3.3 kg, P < 0.05). Leg strength was reduced less in the low-fat (−0.7 ± 1.3%) than in the normal-fat individuals (−10.3 ± 1.5%) 48 h after, compared with before, downhill running ( P < 0.01). Multiple linear regression analysis revealed that the decline in strength could be predicted best by FM/FFM ( r2= 0.44, P < 0.05) and FM-to-thigh lean tissue cross-sectional area ratio ( r2= 0.53, P < 0.05), with no additional variables enhancing the prediction equation. There were no differences in muscle glycogen, creatine phosphate, ATP, or total creatine 48 h after, compared with before, downhill running; however, the change in muscle glycogen after downhill running was associated with a higher FM/FFM ( r = −0.56, P < 0.05). These data suggest that FM/FFM is a major determinant of losses in muscle strength after downhill running.

scholarly journals Vertical hopper compositions for preflexive and feedback-stabilized quadrupedal bounding, pacing, pronking, and trotting

2018 ◽  
Vol 37 (7) ◽  
pp. 743-778 ◽  
Author(s):  
Avik De ◽  
Daniel E. Koditschek
Keyword(s):  
Relative Phase ◽  
Phase Locking ◽  
Formal Analysis ◽  
Feedback Stabilization ◽  
Hybrid Dynamical Systems ◽  
Numerical Studies ◽  
Physical Experiments ◽  
Low Degree ◽  
The Relationship ◽  
Phase Relationships

This paper applies an extension of classical averaging methods to hybrid dynamical systems, thereby achieving formally specified, physically effective and robust instances of all virtual bipedal gaits on a quadrupedal robot. Gait specification takes the form of a three parameter family of coupling rules mathematically shown to stabilize limit cycles in a low degree of freedom template: an abstracted pair of vertical hoppers whose relative phase locking encodes the desired physical leg patterns. These coupling rules produce the desired gaits when appropriately applied to the physical robot. The formal analysis reveals a distinct set of morphological regimes determined by the distribution of the body’s inertia within which particular phase relationships are naturally locked with no need for feedback stabilization (or, if undesired, must be countermanded by the appropriate feedback), and these regimes are shown empirically to analogously govern the physical machine as well. In addition to the mathematical stability analysis and data from physical experiments we summarize a number of extensive numerical studies that explore the relationship between the simple template and its more complicated anchoring body models.

Verification, Validation, and Best Practices for a High-Order, Potential-Flow Boundary Element Method

2015 ◽  
Author(s):  
W. James Doyle ◽  
Lauren S. Schambach ◽  
Marc V. Smith ◽  
Charles Field ◽  
Christopher J. Hart
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Potential Flow ◽  
Best Practice ◽  
High Order ◽  
Data Sets ◽  
Design Environment ◽  
Best Practice Guidelines ◽  
Physical Experiments ◽  
Element Method

Aegir is a medium-fidelity potential flow code that uses a high-order, non-uniform rational B-Spline (NURBS) based boundary-element method for the computation of steady and unsteady ship hydrodynamics. This paper documents verification and validation for Aegir in its steady-state wave resistance prediction mode and Aegir’s LEAPS to Aegir function. A set of best practice guidelines has been created to aid the user in selecting initial input parameters, which reduces the necessary time for verification. This paper also presents validation of the numerical solution versus physical experiments from publically available ship data sets. Aegir has become more prevalent in the naval ship design community and is now a part of the US Navy’s Integrated Hydrodynamic Design Environment (IHDE).

Model Tests With the HVS Semisubmersible for Dry Tree Application

2014 ◽  
Author(s):  
Johyun Kyoung ◽  
Chan-Kyu Yang ◽  
Kostas Lambrakos ◽  
Jim O’Sullivan
Keyword(s):  
Model Tests ◽  
Base Case ◽  
Natural Period ◽  
Depth Limit ◽  
Wave Basin ◽  
Induced Motion ◽  
Motion Performance ◽  
Heave Motion ◽  
Keel Plate ◽  
Measured Response

The global hull motion performance of the HVS semisubmersible for dry tree application is investigated with model tests. The HVS semisubmersible, which has been validated for low heave motion and VIM (Vortex Induced Motion) response, was modified for dry tree application. As a base case, the modification includes a keel plate with riser keel guides at the level of the pontoons. The keel plate is optimally designed to increase the hull heave period to compensate for the heave period reduction in the HVS semisubmersible due to the riser tensioners for the dry tree application. The plate also provides additional viscous damping that decreases the heave response at the heave natural period. The model tests were performed to investigate the in-place hull motion performance for the Gulf of Mexico environmental conditions. The pneumatic riser tensioners were modeled using a spring with dual stiffness. Because of the water depth limit in the wave basin, a truncated mooring was used to simulate the full scale prototype mooring system. An alternate modification to the HVS semisubmersible that includes pontoon plates was also tested and the measured response was compared to the response of the base case. The measured hull responses were correlated with MLTSIM, a Technip in-house nonlinear time-domain 6-DOF motion analysis program.

scholarly journals Analyses of the Prądnik riverbed Shape Based on Archival and Contemporary Data Sets—Old Maps, LiDAR, DTMs, Orthophotomaps and Cross-Sectional Profile Measurements

2020 ◽  
Vol 12 (14) ◽  
pp. 2208 ◽  
Author(s):  
Stanisław Szombara ◽  
Paulina Lewińska ◽  
Anna Żądło ◽  
Marta Róg ◽  
Kamil Maciuk
Keyword(s):  
Remote Sensing ◽  
Survey Methods ◽  
Remote Sensing Data ◽  
Sufficient Information ◽  
Data Sets ◽  
Time Step ◽  
Mountain Areas ◽  
Cross Sectional ◽  
Sensing Data ◽  
Old Maps

Analyses of riverbed shape evolution are crucial for environmental protection and local water management. For narrow rivers located in forested, mountain areas, it is difficult to use remote sensing data used for large river regions. We performed a study of the Prądnik River, located in the Ojców National Park (ONP), Poland. A multitemporal analysis of various data sets was performed. Light detection and ranging (LiDAR)-based data and orthophotomaps were compared with classical survey methods, and 78 cross-sectional profiles were done via GNSS and tachymetry. In order to add an extra time step, the old maps of this region were gathered, and their content was compared with contemporary data. The analysis of remote sensing data suggests that they do not provide sufficient information on the state and changes of riverbanks, river course or river depth. LiDAR data sets do not show river bottoms, and, due to plant life, do not document riverbanks. The orthophotomaps, due to tree coverage and shades, cannot be used for tracking the whole river course. The quality of old maps allows only for general shape analysis over time. This paper shows that traditional survey methods provide sufficient accuracy for such analysis, and the resulted cross-sectional profiles can and should be used to validate other, remote sensing, data sets. We diagnosed problems with the inventory and monitoring of such objects and proposed methods to refine the data acquisition.

The Impact of Volute Versus Collector on Centrifugal Compressor Performance

2002 ◽  
Author(s):  
Y. I. Biba
Keyword(s):  
3D Model ◽  
Internal Flow ◽  
Performance Measurements ◽  
Cross Sectional ◽  
Flow Rates ◽  
Computational Fluid Dynamics Cfd ◽  
Compressor Performance ◽  
The Subject ◽  
Cfd Analyses ◽  
The Impact

As part of a revamp or rerate study, an investigation was undertaken to assess the impact of a collector design versus a volute on compressor performance. The subject compressor was a single stage, axial inlet configuration with a discharge collector rather than the more commonly used scroll volute. The primary distinction between the collector and volute is that the collector cross sectional area is constant at all circumferential locations. A complex 3D model containing the inlet, impeller, low solidity diffuser (LSD), and collector was built. A similar model was also created where the volute was substituted for the collector. Computational Fluid Dynamics (CFD) analyses were performed using these models with results generated at different flow rates. Computational results are presented and compared to test data for collector configuration. The test included standard performance measurements as well as more detailed internal flow data, allowing a credible comparison with the CFD results. Conclusions are drawn with respect to potential compromises in choosing a collector versus a volute.

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