| 1. |
- Wu, Lichuan, et al.
(author)
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Modeling the Vulnerability of Waterway Networks
- 2014
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In: Journal of waterway, port, coastal, and ocean engineering. - 0733-950X .- 1943-5460. ; 140:4, s. 04014012-
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Journal article (peer-reviewed)abstract
- In some areas, rivers and canals interweave into a network, making inland waterway transportation feasible. Significant losses will occur if a vulnerable waterway (where vulnerability is defined in terms of susceptibility to interference and difficulty in restoring the initial state) that is vital to a network is blocked. System vulnerabilities combined with hazard factors trigger disasters; therefore, reducing the vulnerability of a network system is a useful means of reducing major losses. In this paper, a model to calculate vulnerability based on inherent characteristics of waterways such as channel connectivity, transportation efficiency, and economic cost is developed. Three influence factors-importance, efficiency contribution, and loss-are used to build a vulnerability assessment model in which the relative vulnerabilities of various waterways can be assessed and the most vulnerable waterway can be found. Using this model, a simple waterway network is tested to identify vulnerable waterways. (C) 2014 American Society of Civil Engineers.
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| 2. |
- Eskafi, Majid, et al.
(author)
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Framework for Dealing with Uncertainty in the Port Planning Process
- 2022
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In: Journal of Waterway, Port, Coastal and Ocean Engineering. - 0733-950X. ; 147:3
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Journal article (peer-reviewed)abstract
- Globalization has increased international trade where the contribution of maritime transportation is significant. The projection of future port traffic in terms of vessel call and vessel size provides valuable and fundamental input to capacity planning and management, adjusting the direction of port development. In this research, analysis of port traffic is carried out for the Ports of Isafjordur network. The analysis is conducted based on the prediction of port throughput (ie, containerized and noncontainerized cargo, cruise ship call/passenger) in conjunction with port infrastructure
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| 3. |
- Goransson, Gunnel, et al.
(author)
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Ship-Generated Waves and Induced Turbidity in the Gota alv River in Sweden
- 2014
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In: Journal of Waterway, Port, Coastal and Ocean Engineering. - 0733-950X. ; 140:3
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Journal article (peer-reviewed)abstract
- Ship-generated waves were investigated in the Gota alv river, which is a major waterway on the Swedish west coast between the sea and Lake Vanern. Ships with a typical size of 85x15x5 m (lengthxwidthxdraft) travel at speeds between 5 and 10 knots, generating waves that cause sediment transport and erosion along the river bed and banks. Field measurements of the wave properties and turbidity were carried out during 17 ship passages, and comparisons were made with the most commonly used formulas for predicting ship waves. The formula proposed by the Permanent International Association of Navigation Congresses yielded the overall best agreement for the divergent (secondary) waves, whereas the drawdown (primary wave) could best be estimated from the vessel sinkage. The maximum recorded turbidity was mainly a function of the drawdown, and it could be well predicted from the parameterized bed shear stress. In conclusion, ship waves often induce bed and bank erosion in restricted waterways and, although simplistic formulas involve significant uncertainties, they are still useful tools for predictions. However, more studies are needed to determine the influence of a limited river cross section on the wave generation and the relationship between ship waves and sediment transport.
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| 4. |
- Larson, Magnus, et al.
(author)
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Direct Formula to Compute Wave Height and Angle at Incipient Breaking
- 2010
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In: Journal of Waterway, Port, Coastal and Ocean Engineering. - 0733-950X. ; 136:2, s. 119-122
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Journal article (peer-reviewed)abstract
- The purpose of this technical note is to present a new formula to compute the incipient breaking wave properties based on a simplified solution of the wave energy flux conservation equation combined with Snell's law. The execution time and calculated results of the new formula were compared with those of the iterative method which is commonly used in coastal engineering calculations, including in shoreline response modeling. The new formula could be used instead of the iterative method to save calculation time for application in coastal engineering.
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| 5. |
- Pham, Thanh Nam, et al.
(author)
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A Model of Nearshore Waves and Wave-Induced Currents around a Detached Breakwater
- 2010
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In: Journal of Waterway, Port, Coastal and Ocean Engineering. - 0733-950X. ; 136:3, s. 156-176
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Journal article (peer-reviewed)abstract
- A numerical model that combines a random wave transformation and a wave-induced current model was developed in order to predict the wave and current fields around a detached breakwater. The wave field was determined using the EBED model, as reported by Mase in 2001, with a modified energy dissipation term. The surface roller associated with wave breaking was modeled based on a modification of the equations in works by Dally and Brown, and Larson and Kraus, in which the term for the roller energy flux in the alongshore direction was added to the energy balance equation. The nearshore currents and water elevation were determined from the continuity equation together with the depth-averaged momentum equations. The model was validated by three unique high-quality data sets obtained during experiments on detached breakwaters in the large-scale sediment transport facility basin at the Coastal and Hydraulics Laboratory in Vicksburg, Miss. The calculated significant wave height and longshore current were in good agreement with these measurements, whereas the cross-shore current was underestimated because undertow processes were not included in the modeling (depth-averaged equations employed). The calculated wave setup was somewhat overestimated; however, the absolute differences between the calculations and measurements were overall relatively small.
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| 6. |
- Zhu, Fangfang, et al.
(author)
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Investigation of Momentum Correction Factor in the Swash Flow
- 2022
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In: Journal of Waterway, Port, Coastal and Ocean Engineering. - 0733-950X. ; 148:6
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Journal article (peer-reviewed)abstract
- Swash flows are commonly modeled using the nonlinear shallow water equations (NSWEs). In the derivation of the NSWEs, directly from depth-averaging the Navier-Stokes equations, a so-called momentum correction factor, β, emerges. In this study we present a numerical model of the NSWEs that includes β, which is allowed to vary in space and time, and feedback onto the flow. We apply this model to a swash flow, by making use of the vertical flow structure calculated by use of the log-law boundary layer and free flow region. We thereby examine its influence on the swash-flow predictions of a dam-break swash event described in the literature. The numerical results show that the momentum correction factor has a significant effect on the shoreline motion, and flow adjacent to the shoreline, which results in an overprediction of the shoreline with respect to the standard (β = 1, NSWE) approach. Given that consideration of β should yield a more complete description of the swash dynamics, the implication is that the log-law boundary layer model does not describe the flow structure in the swash tip region well. The implication of this is that to achieve accurate modeling at the flow uprush tip, at which point the largest bed shear stresses are typically exerted, a different submodel is required in that vicinity. Equally, it suggests that classical NSWEs also cannot describe the flow at the tip well, and that accurate prediction is achieved despite this inherent deficiency.
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| 7. |
- Kim, Phillip H., et al.
(author)
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UNTAPPED RICHES OF MESO-LEVEL APPLICATIONS IN MULTILEVEL ENTREPRENEURSHIP MECHANISMS
- 2016
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In: Academy of Management Perspectives. - : ACAD MANAGEMENT. - 1558-9080 .- 1943-4529. ; 30:3, s. 273-291
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Journal article (peer-reviewed)abstract
- Entrepreneurial action is embedded within a variety of complex social structures, not all of which can be as easily defined or measured as macro-institutional or micro-individual characteristics. Nonetheless, these multilayered structures collectively hold rich insights-before now underexamined-into the actual causal mechanisms that affect entrepreneurial actions and outcomes. To address this problem, we call on researchers to broaden their levels of analysis and direct their focus to meso-level structures. Although meso-level social structures are widely studied independently, these intermediate levels are seldom integrated into existing multilevel models. We argue that meso-level structures offer untapped riches for enhancing multilevel entrepreneurial mechanisms and discuss how social groups, associations, and other collectives operating at a meso level can play a more distinct, integrative role between the two ends of the institutional spectrum. To provide practical guidance for pursuing such investigations, we adapt Colemans bathtub model to form a robust framework that integrates micro, meso, and macro levels of analysis. Our framework helps alleviate the shortcomings produced by an overdependence on either solely macro- or micro-level entrepreneurial mechanisms and offers fresh insights, as the intermediate level is more deeply integrated into this new framework.
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