VIV Response of a Subsea Jumper in Uniform Current

Subsea jumpers are susceptible to in-line and/or cross-flow vortex induced vibration (VIV) fatigue damage due to sea bottom currents. However, there is no proven industry standard design analysis methodology currently available specifically for assessing subsea jumper VIV response. In 2012, ExxonMobil conducted a jumper VIV model test to assess the validity of potential jumper VIV prediction approaches. A towing test rig was used to expose a small scale jumper model to flow conditions simulating uniform bottom currents. The jumper model was instrumented to acquire acceleration, bending strain and end connection load data. Several accelerometers and strain gauges were installed to enable reconstruction of static and dynamic deformations and bending deflections along the jumper model. Towing tests at different orientations and tow speeds were performed on both a bare pipe model and a straked pipe model. The data were analyzed to examine the frequencies and amplitudes of the jumper vibration. The data from these experiments provide a benchmark for validating jumper VIV prediction approaches. In this paper, the model test program is presented including model testing philosophy, jumper design and fabrication, and high level model test results.

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Improved In-Line Vortex-Induced Vibrations Prediction for Combined In-Line and Cross-Flow Vortex-Induced Vibrations Responses

Journal of Offshore Mechanics and Arctic Engineering ◽

10.1115/1.4038350 ◽

2017 ◽

Vol 140 (3) ◽

Cited By ~ 1

Author(s):

Decao Yin ◽

Elizabeth Passano ◽

Carl M. Larsen

Keyword(s):

Cross Flow ◽

Hydrodynamic Coefficients ◽

Marine Structures ◽

Flexible Pipe ◽

Flexible Beams ◽

Forced Motion ◽

Pipe Model ◽

Vortex Induced Vibrations ◽

Flow Vortex ◽

Semi Empirical

Slender marine structures are subjected to ocean currents, which can cause vortex-induced vibrations (VIV). Accumulated damage due to VIV can shorten the fatigue life of marine structures, so it needs to be considered in the design and operation phase. Semi-empirical VIV prediction tools are based on hydrodynamic coefficients. The hydrodynamic coefficients can either be calculated from experiments on flexible beams by using inverse analysis or theoretical methods, or obtained from forced motion experiments on a circular cylinder. Most of the forced motion experiments apply harmonic motions in either in-line (IL) or crossflow (CF) direction. Combined IL and CF forced motion experiments are also reported. However, measured motions from flexible pipe VIV tests contain higher order harmonic components, which have not yet been extensively studied. This paper presents results from conventional forced motion VIV experiments, but using measured motions taken from a flexible pipe undergoing VIV. The IL excitation coefficients were used by semi-empirical VIV prediction software vivana to perform combined IL and CF VIV calculation. The key IL results are compared with Norwegian Deepwater Programme (NDP) flexible pipe model test results. By using present IL excitation coefficients, the prediction of IL responses for combined IL and CF VIV responses is improved.

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Modeling and design of role engineering in development of access control for dynamic information systems

Bulletin of the Polish Academy of Sciences Technical Sciences ◽

10.2478/bpasts-2013-0058 ◽

2013 ◽

Vol 61 (3) ◽

pp. 569-579 ◽

Cited By ~ 2

Author(s):

A. Poniszewska-Marańda

Keyword(s):

Information Systems ◽

Dynamic Information ◽

Minimal Set ◽

Distributed Information ◽

Heterogeneous Information ◽

System Protection ◽

Level Model ◽

Model Independent ◽

Role Concept ◽

High Level

Abstract Nowadays, the growth and complexity of functionalities of current information systems, especially dynamic, distributed and heterogeneous information systems, makes the design and creation of such systems a difficult task and at the same time, strategic for businesses. A very important stage of data protection in an information system is the creation of a high level model, independent of the software, satisfying the needs of system protection and security. The process of role engineering, i.e. the identification of roles and setting up in an organization is a complex task. The paper presents the modeling and design stages in the process of role engineering in the aspect of security schema development for information systems, in particular for dynamic, distributed information systems, based on the role concept and the usage concept. Such a schema is created first of all during the design phase of a system. Two actors should cooperate with each other in this creation process, the application developer and the security administrator, to determine the minimal set of user’s roles in agreement with the security constraints that guarantee the global security coherence of the system.

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(A review) Vegetation and biotopes of the National Park “Narochansky” with the Map of terrestrial vegetation (S. 1 : 60 000) and the Map of biotopes (S. 1 : 60 000)

Geobotanical mapping ◽

10.31111/geobotmap/2019.68 ◽

2019 ◽

pp. 68-72

Author(s):

E. A. Volkova

Keyword(s):

National Park ◽

Forest Cover ◽

Practical Importance ◽

Vegetation Mapping ◽

Small Scale ◽

Terrestrial Vegetation ◽

Economic Activities ◽

National Academy Of Sciences ◽

Experimental Botany ◽

High Level

A monograph “Vegetation and biotopes of the “Narochansky” National Park was published in Minsk, Belarus in 2017, edited by A. V. Pugachevsky (Grummo et al., 2017). It includes the Map of terrestrial vegetation (S. 1 : 60 000) and the Map of biotopes (S. 1 : 60 000). Some small-scale maps such as the Map of changes in forest cover of the “Narochansky” National Park for the period 1985–2016, the Map of forest loss in the “Narochansky” National Park for the period 1985–2016 and a series of inventory and analytical maps on the basin of the Naroch Lake are given. This monograph can be considered as a small regional Atlas with detailed explanatory texts to the maps. It presents the experience on vegetation mapping accumulated in the Laboratory of Geobotany and Vegetation mapping of the Institute of Experimental Botany of the National Academy of Sciences of Belarus. Despite some critical comments, mainly concerning the biotope map, this publication of Belarusian geobotanists deserves an approval. They received the full answers to the questions posed: “What do we protect?” and “What is a current state of the vegetation of the National Park and the main trends of its dynamics? Cartographic design is made at a high level; the maps have both scientific and practical importance in the planning of environmental and economic activities.

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Integrated Design and Multi-Objective Optimization of a Single Stage Heat-Pump Turbocompressor

Volume 3B: 39th Design Automation Conference ◽

10.1115/detc2013-12180 ◽

2013 ◽

Author(s):

J. Schiffmann

Keyword(s):

Design Optimization ◽

High Efficiency ◽

Integrated Design ◽

Heat Pumps ◽

Small Scale ◽

Multi Objective Optimization ◽

Design Constraints ◽

Multi Objective ◽

Wide Range ◽

Standard Design

Small scale turbomachines in domestic heat pumps reach high efficiency and provide oil-free solutions which improve heat-exchanger performance and offer major advantages in the design of advanced thermodynamic cycles. An appropriate turbocompressor for domestic air based heat pumps requires the ability to operate on a wide range of inlet pressure, pressure ratios and mass flows, confronting the designer with the necessity to compromise between range and efficiency. Further the design of small-scale direct driven turbomachines is a complex and interdisciplinary task. Textbook design procedures propose to split such systems into subcomponents and to design and optimize each element individually. This common procedure, however, tends to neglect the interactions between the different components leading to suboptimal solutions. The authors propose an approach based on the integrated philosophy for designing and optimizing gas bearing supported, direct driven turbocompressors for applications with challenging requirements with regards to operation range and efficiency. Using previously validated reduced order models for the different components an integrated model of the compressor is implemented and the optimum system found via multi-objective optimization. It is shown that compared to standard design procedure the integrated approach yields an increase of the seasonal compressor efficiency of more than 12 points. Further a design optimization based sensitivity analysis allows to investigate the influence of design constraints determined prior to optimization such as impeller surface roughness, rotor material and impeller force. A relaxation of these constrains yields additional room for improvement. Reduced impeller force improves efficiency due to a smaller thrust bearing mainly, whereas a lighter rotor material improves rotordynamic performance. A hydraulically smoother impeller surface improves the overall efficiency considerably by reducing aerodynamic losses. A combination of the relaxation of the 3 design constraints yields an additional improvement of 6 points compared to the original optimization process. The integrated design and optimization procedure implemented in the case of a complex design problem thus clearly shows its advantages compared to traditional design methods by allowing a truly exhaustive search for optimum solutions throughout the complete design space. It can be used for both design optimization and for design analysis.

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High-level model based calibration technique design for SAR ADC

IOP Conference Series Materials Science and Engineering ◽

10.1088/1757-899x/1032/1/012050 ◽

2021 ◽

Vol 1032 ◽

pp. 012050

Author(s):

M N Skripnichenko

Keyword(s):

Sar Adc ◽

Calibration Technique ◽

Model Based ◽

Level Model ◽

High Level

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The Economics of the Soy Kit as an Appropriate Household Technology for Food Entrepreneurs

Food and Nutrition Bulletin ◽

10.1177/0379572120981183 ◽

2021 ◽

Vol 42 (1) ◽

pp. 104-115

Author(s):

Chungmann Kim ◽

Peter Goldsmith

Keyword(s):

International Development ◽

Poverty Reduction ◽

New Technology ◽

Research Question ◽

Development Project ◽

Small Scale ◽

Resource Base ◽

Credit Access ◽

Feed The Future ◽

High Level

Background: The ability for women to operate as food entrepreneurs presents opportunities to leverage at-home production technologies that not only support family nutrition but also generate income. To these ends, the Feed the Future Malawi Agriculture Diversification Activity recently launched a development project involving a new technology, the Soy Kit. The Activity, a USAID (United States Agency for International Development) funded effort, sought to improve nutrition utilizing an underutilized local and highly nutritious feedstuff, soybean, through a woman’s entrepreneurship scheme. Objective: The USAID funded effort provides the overarching research question, whether the Soy Kit is a sustainable technology for delivering nutrition and income through a women’s entrepreneurship scheme. If true, then development practitioners will have a valuable tool, and the associated evidence, to address the important crosscutting themes, of nutrition, poverty, entrepreneurship, and women’s empowerment. To answer this research question, the research team first evaluates the underlying production economics of the kit to measure profitability, return on investment, and operational performance. Second, the team qualitatively and quantitatively assesses the kit’s overall appropriateness as a technology for the developing world. Methods: The team follows the schema of Bower and Brown and utilizes descriptive statistics, and financial techniques to conduct an assessment of the economics and technical appropriateness of the Soy Kit technology. Results: The results show a high level of appropriateness across a number of metrics. For example, the payback period from cash flow is under 6 months and the annual return on capital is 163% when entrepreneurs utilize a domestically sourced kit valued at US$80. Conclusion: The technology matches well with the rhythm of household economy, in particular women’s labor availability and resource base. Businesses earn significant returns on capital thus appear to be sustainable without donor subsidy. At the same time, available capital to finance kit entrepreneurs appears to be scarce. More research needs to take place to address the credit access question, in order to make small-scale kit entrepreneur truly self-reliant; the effects on poverty reduction at the household and village level; and nutrition improvement among the consumers.

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Dynamic modelling of a servo self-pierce riveting (SPR) process

Proceedings of the Institution of Mechanical Engineers Part B Journal of Engineering Manufacture ◽

10.1177/09544054211037493 ◽

2021 ◽

pp. 095440542110374

Author(s):

Daniel Tang ◽

Mike Evans ◽

Paul Briskham ◽

Luca Susmel ◽

Neil Sims

Keyword(s):

Dynamic Modelling ◽

System Level ◽

Optimum Process ◽

Current Limit ◽

Level Model ◽

System Level Model ◽

Head Height ◽

Extensive Experimental Data ◽

High Level

Self-pierce riveting (SPR) is a complex joining process where multiple layers of material are joined by creating a mechanical interlock via the simultaneous deformation of the inserted rivet and surrounding material. Due to the large number of variables which influence the resulting joint, finding the optimum process parameters has traditionally posed a challenge in the design of the process. Furthermore, there is a gap in knowledge regarding how changes made to the system may affect the produced joint. In this paper, a new system-level model of an inertia-based SPR system is proposed, consisting of a physics-based model of the riveting machine and an empirically-derived model of the joint. Model predictions are validated against extensive experimental data for multiple sets of input conditions, defined by the setting velocity, motor current limit and support frame type. The dynamics of the system and resulting head height of the joint are predicted to a high level of accuracy. Via a model-based case study, changes to the system are identified, which enable either the cycle time or energy consumption to be substantially reduced without compromising the overall quality of the produced joint. The predictive capabilities of the model may be leveraged to reduce the costs involved in the design and validation of SPR systems and processes.

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