scholarly journals LCTC Ships Concept Design in the North Europe- Mediterranean Transport Scenario Focusing on Intact Stability Issues

2021 ◽  
Vol 9 (3) ◽  
pp. 278
Author(s):  
Germano Degan ◽  
Luca Braidotti ◽  
Alberto Marinò ◽  
Vittorio Bucci
Keyword(s):  
Design Stage ◽  
Strong Impact ◽  
Large Set ◽  
Concept Design ◽  
The North ◽  
Design Alternatives ◽  
Intact Stability ◽  
Multi Attribute Decision Making ◽  
Stability Issues ◽  
The Impact

In late years, the size of RoRo cargo ships has continuously increased, leading to the so-called Large Car Truck Carriers (LCTC). The design of these vessels introduced new challenges that shall be considered during the ship design since the conceptual stage, which has a very strong impact on the technical and economic performances of the vessel during all its life-cycle. In this work, the concept design of an LCTC is presented based on Multi-Attribute Decision Making (MADM). A large set of design alternatives have been generated and compared in order to find out the most promising feasible designs. The proposed approach is based on a Mathematical Design Model (MDM) capable to assess all the main technical and economic characteristics for each design. Among the others, here focus has been done on the ship stability to assure the compliance with statutory rules within the MDM. A new stability metamodel has been developed capable to define the cross curves of stability at the concept design stage. The proposed MADM methodology has been applied to North Europe-Mediterranean transport scenario highlighting the impact of main particulars describing hull geometry on the technical and economic performances of an LCTC ship.

scholarly journals Simulating the vegetation response to abrupt climate changes under glacial conditions with the ORCHIDEE/IPSL models

2012 ◽  
Vol 9 (9) ◽  
pp. 12895-12950
Author(s):  
M.-N. Woillez ◽  
M. Kageyama ◽  
N. Combourieu-Nebout ◽  
G. Krinner
Keyword(s):  
General Circulation ◽  
Western Europe ◽  
Circulation Model ◽  
Meridional Overturning Circulation ◽  
Strong Impact ◽  
The North ◽  
Freshwater Fluxes ◽  
Global Vegetation ◽  
The Impact ◽  
Pollen Records

Abstract. The last glacial period has been punctuated by two types of abrupt climatic events, the Dansgaard-Oeschger (DO) and Heinrich (HE) events. These events, recorded in Greenland ice and in marine sediments, involved changes in the Atlantic Meridional Overturning Circulation (AMOC) and led to major changes in the terrestrial biosphere. Here we use the dynamical global vegetation model ORCHIDEE to simulate the response of vegetation to abrupt changes in the AMOC strength. To do so, we force ORCHIDEE off-line with outputs from the IPSL_CM4 general circulation model, in which we have forced the AMOC to change by adding freshwater fluxes in the North Atlantic. We investigate the impact of a collapse and recovery of the AMOC, at different rates, and focus on Western Europe, where many pollen records are available to compare with. The impact of an AMOC collapse on the European mean temperatures and precipitations simulated by the GCM is relatively small but sufficient to drive an important regression of forests and expansion of grasses in ORCHIDEE, in qualitative agreement with pollen data for an HE event. On the contrary, a run with a rapid shift of the AMOC to an hyperactive state of 30 Sv, mimicking the warming phase of a DO event, does not exhibit a strong impact on the European vegetation compared to the glacial control state. For our model, simulating the impact of an HE event thus appears easier than simulating the abrupt transition towards the interstadial phase of a DO. For both a collapse or a recovery of the AMOC the vegetation starts to respond to climatic changes immediately but reaches equilibrium about 200 yr after the climate equilibrates, suggesting a possible bias in the climatic reconstructions based on pollen records, which assume equilibrium between climate and vegetation. However, our study does not take into account vegetation feedbacks on the atmosphere.

scholarly journals A Model for Intact and Damage Stability Evaluation of CNG Ships during the Concept Design Stage

2019 ◽  
Vol 7 (12) ◽  
pp. 450 ◽  
Author(s):  
Francesco Mauro ◽  
Luca Braidotti ◽  
Giorgio Trincas
Keyword(s):  
Natural Gas ◽  
Design Process ◽  
Design Stage ◽  
Concept Design ◽  
Compressed Natural Gas ◽  
Hull Form ◽  
Intact Stability ◽  
Damage Stability ◽  
Marine Engineering ◽  
Feasible Solutions

To face the design of a new ship concept, the evaluation of multiple feasible solutions concerning several aspects of naval architecture and marine engineering is necessary. Compressed natural gas technologies are in continuous development; therefore, there are no available databases for existing ships to use as a basis for the design process of a new unit. In this sense, the adoption of a modern multi-attribute decision-based method can help the designer for the study of a completely new ship prototype. A database of compressed natural gas ships was generated starting from a baseline hull, varying six hull-form parameters by means of the design of experiment technique. Between the attributes involved in the concept design process, stability is for sure one of the most relevant topics, both for intact and damaged cases. This work describes two approaches to identify the compliance of a ship with the intact stability regulations based on the ship main geometrical quantities. Moreover, a metamodel based on the maximum floodable length concept (damage stability) allows determining the main internal subdivision of the ship. The metamodel outcomes were compared with results from direct calculations on a ship external to the database, highlighting the adequate accuracy given by the developed methods.

scholarly journals Simulating the vegetation response in western Europe to abrupt climate changes under glacial background conditions

2013 ◽  
Vol 10 (3) ◽  
pp. 1561-1582 ◽  
Author(s):  
M.-N. Woillez ◽  
M. Kageyama ◽  
N. Combourieu-Nebout ◽  
G. Krinner
Keyword(s):  
General Circulation ◽  
Western Europe ◽  
Circulation Model ◽  
Meridional Overturning Circulation ◽  
Strong Impact ◽  
The North ◽  
Freshwater Fluxes ◽  
Global Vegetation ◽  
The Impact ◽  
Pollen Records

Abstract. The last glacial period has been punctuated by two types of abrupt climatic events, the Dansgaard–Oeschger (DO) and Heinrich (HE) events. These events, recorded in Greenland ice and in marine sediments, involved changes in the Atlantic Meridional Overturning Circulation (AMOC) and led to major changes in the terrestrial biosphere. Here we use the dynamical global vegetation model ORCHIDEE to simulate the response of vegetation to abrupt changes in the AMOC strength. We force ORCHIDEE offline with outputs from the IPSL_CM4 general circulation model, in which the AMOC is forced to change by adding freshwater fluxes in the North Atlantic. We investigate the impact of a collapse and recovery of the AMOC, at different rates, and focus on Western Europe, where many pollen records are available for comparison. The impact of an AMOC collapse on the European mean temperatures and precipitations simulated by the GCM is relatively small but sufficient to drive an important regression of forests and expansion of grasses in ORCHIDEE, in qualitative agreement with pollen data for an HE event. On the contrary, a run with a rapid shift of the AMOC to a hyperactive state of 30 Sv, mimicking the warming phase of a DO event, does not exhibit a strong impact on the European vegetation compared to the glacial control state. For our model, simulating the impact of an HE event thus appears easier than simulating the abrupt transition towards the interstadial phase of a DO. For both a collapse or a recovery of the AMOC, the vegetation starts to respond to climatic changes immediately but reaches equilibrium about 200 yr after the climate equilibrates, suggesting a possible bias in the climatic reconstructions based on pollen records, which assume equilibrium between climate and vegetation. However, our study does not take into account vegetation feedbacks on the atmosphere.

Reasoning about system-level failure behavior from large sets of function-based simulations

2014 ◽  
Vol 28 (4) ◽  
pp. 385-398 ◽  
Author(s):  
David C. Jensen ◽  
Oladapo Bello ◽  
Christopher Hoyle ◽  
Irem Y. Tumer
Keyword(s):  
Clustering Algorithm ◽  
Latent Class ◽  
Probability Model ◽  
System Level ◽  
Design Stage ◽  
Failure Behavior ◽  
Large Set ◽  
Large Sets ◽  
Potential System ◽  
The Impact

AbstractThis paper presents the use of data clustering methods applied to the analysis results of a design-stage, functional failure reasoning tool. A system simulation using qualitative descriptions of component behaviors and a functional reasoning tool are used to identify the functional impact of a large set of potential single and multiple fault scenarios. The impact of each scenario is collected as the set of categorical function “health” states for each component-level function in the system. This data represents the space of potential system states. The clustering and statistical tools presented in this paper are used to identify patterns in this system state space. These patterns reflect the underlying emergent failure behavior of the system. Specifically, two data analysis tools are presented and compared. First, a modifiedk-means clustering algorithm is used with a distance metric of functional effect similarity. Second, a statistical approach known as latent class analysis is used to find an underlying probability model of potential system failure states. These tools are used to reason about how the system responds to complex fault scenarios and assists in identifying potential design changes for fault mitigation. As computational power increases, the ability to reason with large sets of data becomes as critical as the analysis methods used to collect that data. The goal of this work is to provide complex system designers with a means of using early design simulation data to identify and mitigate potential emergent failure behavior.

scholarly journals The impact of clustering and angular resolution on far-infrared and millimeter continuum observations

2017 ◽  
Vol 607 ◽  
pp. A89 ◽  
Author(s):  
Matthieu Béthermin ◽  
Hao-Yi Wu ◽  
Guilaine Lagache ◽  
Iary Davidzon ◽  
Nicolas Ponthieu ◽  
...  
Keyword(s):  
Flux Density ◽  
Galaxy Evolution ◽  
Angular Resolution ◽  
Power Spectra ◽  
Far Infrared ◽  
High Angular Resolution ◽  
Strong Impact ◽  
Large Set ◽  
Number Counts ◽  
The Impact

Follow-up observations at high-angular resolution of bright submillimeter galaxies selected from deep extragalactic surveys have shown that the single-dish sources are comprised of a blend of several galaxies. Consequently, number counts derived from low- and high-angular-resolution observations are in tension. This demonstrates the importance of resolution effects at these wavelengths and the need for realistic simulations to explore them. We built a new 2 deg2 simulation of the extragalactic sky from the far-infrared to the submillimeter. It is based on an updated version of the 2SFM (two star-formation modes) galaxy evolution model. Using global galaxy properties generated by this model, we used an abundance-matching technique to populate a dark-matter lightcone and thus simulate the clustering. We produced maps from this simulation and extracted the sources, and we show that the limited angular resolution of single-dish instruments has a strong impact on (sub)millimeter continuum observations. Taking into account these resolution effects, we are reproducing a large set of observables, as number counts and their evolution with redshift and cosmic infrared background power spectra. Our simulation consistently describes the number counts from single-dish telescopes and interferometers. In particular, at 350 and 500 μm, we find that the number counts measured by Herschel between 5 and 50 mJy are biased towards high values by a factor ~2, and that the redshift distributions are biased towards low redshifts. We also show that the clustering has an important impact on the Herschel pixel histogram used to derive number counts from P(D) analysis. We find that the brightest galaxy in the beam of a 500 μm Herschel source contributes on average to only ~60% of the Herschel flux density, but that this number will rise to ~95% for future millimeter surveys on 30 m-class telescopes (e.g., NIKA2 at IRAM). Finally, we show that the large number density of red Herschel sources found in observations but not in models might be an observational artifact caused by the combination of noise, resolution effects, and the steepness of color- and flux density distributions. Our simulation, called Simulated Infrared Dusty Extragalactic Sky (SIDES), is publicly available.

scholarly journals Impact of assimilating a merged sea-ice thickness from CryoSat-2 and SMOS in the Arctic reanalysis

2018 ◽  
Vol 12 (11) ◽  
pp. 3671-3691 ◽  
Author(s):  
Jiping Xie ◽  
François Counillon ◽  
Laurent Bertino
Keyword(s):  
Sea Ice ◽  
Degrees Of Freedom ◽  
The Arctic ◽  
Ice Thickness ◽  
Large Set ◽  
Sea Ice Thickness ◽  
The North ◽  
Ice Drift ◽  
Marine Environment Monitoring ◽  
The Impact

Abstract. Accurately forecasting the sea-ice thickness (SIT) in the Arctic is a major challenge. The new SIT product (referred to as CS2SMOS) merges measurements from the CryoSat-2 and SMOS satellites on a weekly basis during the winter. The impact of assimilating CS2SMOS data is tested for the TOPAZ4 system – the Arctic component of the Copernicus Marine Environment Monitoring Services (CMEMS). TOPAZ4 currently assimilates a large set of ocean and sea-ice observations with the Deterministic Ensemble Kalman Filter (DEnKF). Two parallel reanalyses are conducted without (Official run) and with (Test run) assimilation of CS2SMOS data from 19 March 2014 to 31 March 2015. Since only mapping errors were provided in the CS2SMOS observation, an arbitrary term was added to compensate for the missing errors, but was found a posteriori too large. The SIT bias (too thin) is reduced from 16 to 5 cm and the standard errors decrease from 53 to 38 cm (by 28 %) when compared to the assimilated SIT. When compared to independent SIT observations, the error reduction is 24 % against the ice mass balance (IMB) buoy 2013F and by 12.5 % against SIT data from the IceBridge campaigns. The improvement of sea-ice volume persists through the summer months in the absence of CS2SMOS data. Comparisons to sea-ice drift from the satellites show that dynamical adjustments reduce the drift errors around the North Pole by about 8 %–9 % in December 2014 and February 2015. Finally, using the degrees of freedom for signal (DFS), we find that CS2SMOS makes the prime source of information in the central Arctic and in the Kara Sea. We therefore recommend the assimilation of C2SMOS for Arctic reanalyses in order to improve the ice thickness and the ice drift.

Expected Accuracy Range of Cost Estimates for Small Modular Reactors at the Early Concept Design Stage

2018 ◽  
Author(s):  
Amritpal S. Agar ◽  
Andy J. Fry ◽  
Martin J. Goodfellow ◽  
Yee M. Goh ◽  
Linda B. Newnes
Keyword(s):  
Power Generation ◽  
Life Cycle ◽  
Life Cycle Cost ◽  
Nuclear Power ◽  
Design Stage ◽  
Concept Design ◽  
Cost Estimates ◽  
Cost Uncertainty ◽  
Small Modular Reactors ◽  
The Impact

Life cycle cost is an important consideration for the development and selection of new power generation technology. Large nuclear power plants (NPPs) have been subject to capital cost escalation, stemming from delays related to late design changes, procurement issues for major components, and regulatory enforced changes. These factors have contributed to the significant risk premium associated with gigawatt scale “Gen III+” designs, which have incurred significant financing costs. Large NPPs have become prohibitively expensive for many utility investors in liberalized markets and smaller economies. The challenge of reducing upfront capital costs is one of the requirements that have driven the development of innovative Small Modular Reactors (SMRs). These designs are said to offer reduced unit cost and reduced risk due to certainty of delivery, which could lead to a lower cost of capital for a utility customer. By offering a product with more cost certainty the SMR could restore investor confidence in nuclear power. The life cycle cost estimates associated with the different SMR designs are uncertain at the early stage of development. However, designers need to understand, with some confidence, the impact of technical decisions at the early development phase on the life cycle cost. This study presents an overview of cost uncertainty associated with the early design stage of the SMR. The types of cost estimating approaches available at the concept design phase are identified and categorized in terms of their expected accuracy ranges. The Overnight Cost of Construction (OCC) is an important driver of the life cycle cost of a power generation project. The expected accuracy ranges from each estimating method are used to illustrate the sensitivity of cost uncertainty to the level of design maturity. By understanding the sources and impact of cost uncertainty decision making during product development can be optimized to meet both technical and commercial requirements.

Early-Stage Analysis for MEMS Structural Optimization II: Its Application to Microrelay Reliability

2005 ◽  
Author(s):  
Koji Ishikawa ◽  
Takahiro Miki ◽  
Hiroki Mamiya ◽  
Q. Yu
Keyword(s):  
Structural Optimization ◽  
Mechanical Performance ◽  
Early Stage ◽  
Design Stage ◽  
Design Parameters ◽  
Total System ◽  
Concept Design ◽  
Restoring Force ◽  
Electrostatic Actuators ◽  
The Impact

This paper discusses a new structural optimization methodology for MEMS and its application to reliability evaluation of micro relays. Clarifying the relationship between system characteristics and design factors, our new design optimization method (called MESA) enables numerical evaluation of MEMS structures at the concept design stage. The relation is defined as sensitivity, which is calculated based on the system governing equations with an experimental method technique and a FEM analysis. The sensitivities show not only the effect of design parameters for the system performances but also the system tradeoffs. The MESA allows designers to obtain “rough” total system performance and create a new concept. The MESA is successfully applied to evaluate an electrostatic microrelay for DC/RF signal switching. With the aid of the MESA, we define existing problems of current cantilever-shape MEMS switches and propose new mechanical approaches in order to enhance the mechanical reliability. The MESA clearly shows us that there are tradeoffs in the switching phenomenon of cantilever microrelay. Based on the MESA information, a new switching concept, which has tri-state multi-finger lateral contacts, is established and the MEMS structure is designed and fabricated. The tri-state switching concept reduces the number of contacts and also disperses the impact energy, which aggravates adhesion. In addition, bi-electrostatic actuators increase the adverse force to prevent stiction without the increase of restoring force, which causes degradation or cracks of the contact surfaces. Furthermore, a new push-pull switching structure is designed as a second generation by means of the MESA. The MESA shows that the second concept will provide superior mechanical performance with keeping the high RF isolation.

When Do Psychopathic Traits Affect Cooperative Behavior?: An Iterated Prisoner's Dilemma Experimental Study

2020 ◽  
Author(s):  
M Testori ◽  
M Kempf ◽  
RB Hoyle ◽  
Hedwig Eisenbarth
Keyword(s):  
Prisoner's Dilemma ◽  
Cooperative Behavior ◽  
Prisoner’S Dilemma ◽  
Selection Procedure ◽  
Psychopathic Traits ◽  
Strong Impact ◽  
Iterated Prisoner's Dilemma ◽  
Human Decision ◽  
The Impact ◽  
Iterated Prisoner’S Dilemma

© 2019 Hogrefe Publishing. Personality traits have been long recognized to have a strong impact on human decision-making. In this study, a sample of 314 participants took part in an online game to investigate the impact of psychopathic traits on cooperative behavior in an iterated Prisoner's dilemma game. We found that disinhibition decreased the maintenance of cooperation in successive plays, but had no effect on moving toward cooperation after a previous defection or on the overall level of cooperation over rounds. Furthermore, our results underline the crucial importance of a good model selection procedure, showing how a poor choice of statistical model can provide misleading results.

Sign in / Sign up

Export Citation Format

Share Document