Pub Date : 2014-09-01DOI: 10.1109/OCEANS.2014.7003129
W. Duan, Y. R. Zheng
An iterative bidirectional soft decision feedback equalizer (Bi-SDFE) is proposed for robust multiple-input multiple-output (MIMO) underwater acoustic (UWA) communications. The proposed Bi-SDFE use a time-reversed soft decision feedback equalizer (SDFE) in conjunction with a normal SDFE to lower the error propagation in severe inter-symbol interference (ISI) channels. The extrinsic information at the equalizer outputs are combined to improve the reliability and reduce the probability of catastrophic performance. Besides, the normalized least mean squares (NLMS) algorithm is adopted to iteratively estimate the MIMO UWA channel for the equalizer. The performance of the proposed algorithm is verified by the SPACE08 experiment. The processing results show that the iterative Bi-SDFE can effectively improve system performance and data efficiency in time varying MIMO UWA channel.
{"title":"Bidirectional soft-decision feedback equalization for robust MIMO underwater acoustic communications","authors":"W. Duan, Y. R. Zheng","doi":"10.1109/OCEANS.2014.7003129","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003129","url":null,"abstract":"An iterative bidirectional soft decision feedback equalizer (Bi-SDFE) is proposed for robust multiple-input multiple-output (MIMO) underwater acoustic (UWA) communications. The proposed Bi-SDFE use a time-reversed soft decision feedback equalizer (SDFE) in conjunction with a normal SDFE to lower the error propagation in severe inter-symbol interference (ISI) channels. The extrinsic information at the equalizer outputs are combined to improve the reliability and reduce the probability of catastrophic performance. Besides, the normalized least mean squares (NLMS) algorithm is adopted to iteratively estimate the MIMO UWA channel for the equalizer. The performance of the proposed algorithm is verified by the SPACE08 experiment. The processing results show that the iterative Bi-SDFE can effectively improve system performance and data efficiency in time varying MIMO UWA channel.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122273373","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-09-01DOI: 10.1109/OCEANS.2014.7003217
Donal Kennedy, M. Walsh, B. O’flynn
Commercial wave buoys, while accurate and reliable, utilize high specification components which can render the cost of deployment and maintenance prohibitively high for many applications. This paper describes the deployment of Tyndall Wireless Inertial Measurement Units (WIMUs) as applied to measurement of ocean waves. These inertial measurement units are miniature devices which combine a microcontroller, wireless communication capability, and solidstate MEMS sensors (accelerometer, gyroscope and magnetometer) with specialized algorithms for specific analytical tasks. The deployments include testing on a laboratory based rig and in an artificial wave tank. Sea state parameters are extracted from the inertial data using a zero-crossing method, incorporating two different methodologies with the results of each compared. Height measurement accuracy is shown to be significantly improved over previous studies in this field, with average wave height (Hav) error of less than 1% ±7%.
{"title":"Development of a miniature, low-cost wave measurement solution","authors":"Donal Kennedy, M. Walsh, B. O’flynn","doi":"10.1109/OCEANS.2014.7003217","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003217","url":null,"abstract":"Commercial wave buoys, while accurate and reliable, utilize high specification components which can render the cost of deployment and maintenance prohibitively high for many applications. This paper describes the deployment of Tyndall Wireless Inertial Measurement Units (WIMUs) as applied to measurement of ocean waves. These inertial measurement units are miniature devices which combine a microcontroller, wireless communication capability, and solidstate MEMS sensors (accelerometer, gyroscope and magnetometer) with specialized algorithms for specific analytical tasks. The deployments include testing on a laboratory based rig and in an artificial wave tank. Sea state parameters are extracted from the inertial data using a zero-crossing method, incorporating two different methodologies with the results of each compared. Height measurement accuracy is shown to be significantly improved over previous studies in this field, with average wave height (Hav) error of less than 1% ±7%.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130893285","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-09-01DOI: 10.1109/OCEANS.2014.7003004
N. Stark, A. Hay, Greg Trowse
Soil mechanical properties of the seabed are related to a number of challenges in the development of ocean renewable energy. Early site assessment is an important part of the development of an ocean renewable energy project, and soil mechanical and sediment dynamical site characteristics should already be addressed at this stage. However, the suitability of the site for the installation of a ocean renewable energy converter (OREC) is still under evaluation and budgets are often strongly limited at this stage of the project. It follows that there is a need for cost-efficient survey strategies. Different methods have been tested in a tidal energy project in the Bay of Fundy, Canada, and a wave energy project in Yakutat, Alaska. Camera systems displayed sediment type, abundance of rocks, plants and small-scale bedforms. Portable free-fall penetrometers were deployed for testing of sediment strength and stratification at the uppermost seafloor. Areas of different sediment strength were identified, and loose, poorly compacted sediment layers quantified. Additionally, rocks and bedrock faces which were covered by a thin sediment layer and remained undetected by seafloor imaging sonars and grab samples, were found. Buried pressure sensors were used in preliminary experiments to monitor pore pressure variations with wave forcing and test the susceptibility to sediment liquefaction. First surveys using these methods attested that they deliver valuable information with regard to sediment and soil mechanical characteristics, while being deployable from local small fishery or harbor authority vessels. Availability of such vessels and devices is high, while purchasing/renting costs are rather low. This allows to perform such tests very cost-effectively, and thus provides a promising strategy for early site assessment in ocean structure engineering before larger budgets are available.
{"title":"Cost-effective geotechnical and sedimentological early site assessment for ocean renewable energies","authors":"N. Stark, A. Hay, Greg Trowse","doi":"10.1109/OCEANS.2014.7003004","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003004","url":null,"abstract":"Soil mechanical properties of the seabed are related to a number of challenges in the development of ocean renewable energy. Early site assessment is an important part of the development of an ocean renewable energy project, and soil mechanical and sediment dynamical site characteristics should already be addressed at this stage. However, the suitability of the site for the installation of a ocean renewable energy converter (OREC) is still under evaluation and budgets are often strongly limited at this stage of the project. It follows that there is a need for cost-efficient survey strategies. Different methods have been tested in a tidal energy project in the Bay of Fundy, Canada, and a wave energy project in Yakutat, Alaska. Camera systems displayed sediment type, abundance of rocks, plants and small-scale bedforms. Portable free-fall penetrometers were deployed for testing of sediment strength and stratification at the uppermost seafloor. Areas of different sediment strength were identified, and loose, poorly compacted sediment layers quantified. Additionally, rocks and bedrock faces which were covered by a thin sediment layer and remained undetected by seafloor imaging sonars and grab samples, were found. Buried pressure sensors were used in preliminary experiments to monitor pore pressure variations with wave forcing and test the susceptibility to sediment liquefaction. First surveys using these methods attested that they deliver valuable information with regard to sediment and soil mechanical characteristics, while being deployable from local small fishery or harbor authority vessels. Availability of such vessels and devices is high, while purchasing/renting costs are rather low. This allows to perform such tests very cost-effectively, and thus provides a promising strategy for early site assessment in ocean structure engineering before larger budgets are available.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130535348","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-09-01DOI: 10.1109/OCEANS.2014.7003173
S. Ishibashi, Y. Ota, H. Yoshida, M. Sugesawa, F. Fan
JAMSTEC developed some new underwater vehicles. One of them is “OTOHIME”. Because it was designed as a multi-mission type, it has not only the cruising ability but also the working ability through its skid is exchanged or desorbed. In order it to perform various missions, its control system was newly developed as a multi-CPU control unit. The control system is mainly composed of seven CPUs and they are connected to each other with an Ether-network. And each CPU executes some different processes and controls some different devices which are installed into it, respectively. Thus the control system can realize the load distribution of a CPU, the trouble detection of the system, the function compensation and the self-restoration owing to the information sharing applying the Ether-network. Now, sea trials were carried out in order to verify the performance of some new technologies which have been already applied into it. And then the utility of the control system was also confirmed.
{"title":"Multi-mission underwater vehicle “OTOHIME” and its control system","authors":"S. Ishibashi, Y. Ota, H. Yoshida, M. Sugesawa, F. Fan","doi":"10.1109/OCEANS.2014.7003173","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003173","url":null,"abstract":"JAMSTEC developed some new underwater vehicles. One of them is “OTOHIME”. Because it was designed as a multi-mission type, it has not only the cruising ability but also the working ability through its skid is exchanged or desorbed. In order it to perform various missions, its control system was newly developed as a multi-CPU control unit. The control system is mainly composed of seven CPUs and they are connected to each other with an Ether-network. And each CPU executes some different processes and controls some different devices which are installed into it, respectively. Thus the control system can realize the load distribution of a CPU, the trouble detection of the system, the function compensation and the self-restoration owing to the information sharing applying the Ether-network. Now, sea trials were carried out in order to verify the performance of some new technologies which have been already applied into it. And then the utility of the control system was also confirmed.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129523659","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-09-01DOI: 10.1109/OCEANS.2014.7003253
E. M. Garcia, C. Chang, Hongrae Park, M. Bernitsas
For many decades now, the idea of Vortex-Induced Vibrations (VIV) being modeled as a lock-in phenomenon of a mass-spring-dashpot system with an ideal added mass term has prevailed. In 2000, it was suggested by Vikestad et al. [1] that VIV may be modeled as a resonance phenomenon with variable natural frequency due to a variable added-mass term. In this paper, the variable added-mass approach is used for analysis of VIV at various added damping values. Additionally, Vandiver's damping coefficient c* is used [2] to correlate damping to lift. The findings are that: 1. The oscillation frequency is in unity with the mean of the natural frequency with variable added mass for each period of oscillation during VIV lock-in no matter the damping value. 2. The time-averaged variable added mass coefficient is shown to vary with an increasing damping coefficient, where below a reduced velocity of approximately seven, increased damping indicates increased added mass. After a reduced velocity of approximately seven, however, increased damping results in decreased added mass. 3. Vandiver's damping coefficient c* plotted against the nondimensional amplitude follows very closely to c*A/D = max lift coefficient = square root of 0.79 [3]. A handful of cases did exceed square root of 0.79 but only marginally.
{"title":"Effect of damping on variable added mass and lift of circular cylinders in vortex-induced vibrations","authors":"E. M. Garcia, C. Chang, Hongrae Park, M. Bernitsas","doi":"10.1109/OCEANS.2014.7003253","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003253","url":null,"abstract":"For many decades now, the idea of Vortex-Induced Vibrations (VIV) being modeled as a lock-in phenomenon of a mass-spring-dashpot system with an ideal added mass term has prevailed. In 2000, it was suggested by Vikestad et al. [1] that VIV may be modeled as a resonance phenomenon with variable natural frequency due to a variable added-mass term. In this paper, the variable added-mass approach is used for analysis of VIV at various added damping values. Additionally, Vandiver's damping coefficient c* is used [2] to correlate damping to lift. The findings are that: 1. The oscillation frequency is in unity with the mean of the natural frequency with variable added mass for each period of oscillation during VIV lock-in no matter the damping value. 2. The time-averaged variable added mass coefficient is shown to vary with an increasing damping coefficient, where below a reduced velocity of approximately seven, increased damping indicates increased added mass. After a reduced velocity of approximately seven, however, increased damping results in decreased added mass. 3. Vandiver's damping coefficient c* plotted against the nondimensional amplitude follows very closely to c*A/D = max lift coefficient = square root of 0.79 [3]. A handful of cases did exceed square root of 0.79 but only marginally.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128707089","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-09-01DOI: 10.1109/OCEANS.2014.7003192
M. Biagi, S. Rinauro, S. Colonnese, R. Cusani, G. Scarano
In this paper we investigate how to rephrase the concepts of cognitive access, originally developed for radio communications, in the framework of underwater acoustic communications. Differently from classical cognitive radio access, where each signal at the receiver is generated by a communication source, in the underwater scenario acoustic signals at the general receive node are likely to be due to communication source as well as natural/artificial acoustic sources (e.g mammals, ship engines and so forth). In order to maximize the access probability for cognitive acoustic nodes, we then focus on understanding the nature of the sensed interference via the tools of image classification, being the image the spectrogram of the acquired signal.
{"title":"Understanding interference by cognitive nodes: The underwater case","authors":"M. Biagi, S. Rinauro, S. Colonnese, R. Cusani, G. Scarano","doi":"10.1109/OCEANS.2014.7003192","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003192","url":null,"abstract":"In this paper we investigate how to rephrase the concepts of cognitive access, originally developed for radio communications, in the framework of underwater acoustic communications. Differently from classical cognitive radio access, where each signal at the receiver is generated by a communication source, in the underwater scenario acoustic signals at the general receive node are likely to be due to communication source as well as natural/artificial acoustic sources (e.g mammals, ship engines and so forth). In order to maximize the access probability for cognitive acoustic nodes, we then focus on understanding the nature of the sensed interference via the tools of image classification, being the image the spectrogram of the acquired signal.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128658869","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-09-01DOI: 10.1109/OCEANS.2014.7003244
D. Wallace, B. de Young, S. Iverson, J. LaRoche, F. Whoriskey, M. Lewis, P. Archambault, F. Davidson, D. Gilbert, B. Greenan, P. Pepin, C. Johnson, D. Hebert, Neil Gall, J. Hanlon, S. Rysgaard, B. Carter, Randy Gillespie, Dwight House, P. Snelgrove, P. Myers, M. Babin, P. Holthus, World Ocean Council, A. Rae
We review opportunities, impediments, regional scope and principles for a Canadian contribution to an Integrated Atlantic Ocean Observing System (IAOOS) in the context of the Galway Alliance. This contribution should build on what exists, plan ahead for data management and data access, be flexible and sustainable, encourage international involvement, be science-led, foster research aggregation, and have close links to remote sensing, data assimilation and prediction programs. Existing programs that can contribute are described, and new initiatives that will broaden relevance of the Observing System are identified, including biological/ ecosystem observations. Specific platforms and technologies for both near-shore and offshore waters are listed, together with areas where new developments are needed. Finally, we outline a strategy for the development of an Atlantic Canada Regional Ocean Observing System (ACROOS).
{"title":"A Canadian contribution to an integrated Atlantic ocean observing system (IAOOS)","authors":"D. Wallace, B. de Young, S. Iverson, J. LaRoche, F. Whoriskey, M. Lewis, P. Archambault, F. Davidson, D. Gilbert, B. Greenan, P. Pepin, C. Johnson, D. Hebert, Neil Gall, J. Hanlon, S. Rysgaard, B. Carter, Randy Gillespie, Dwight House, P. Snelgrove, P. Myers, M. Babin, P. Holthus, World Ocean Council, A. Rae","doi":"10.1109/OCEANS.2014.7003244","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003244","url":null,"abstract":"We review opportunities, impediments, regional scope and principles for a Canadian contribution to an Integrated Atlantic Ocean Observing System (IAOOS) in the context of the Galway Alliance. This contribution should build on what exists, plan ahead for data management and data access, be flexible and sustainable, encourage international involvement, be science-led, foster research aggregation, and have close links to remote sensing, data assimilation and prediction programs. Existing programs that can contribute are described, and new initiatives that will broaden relevance of the Observing System are identified, including biological/ ecosystem observations. Specific platforms and technologies for both near-shore and offshore waters are listed, together with areas where new developments are needed. Finally, we outline a strategy for the development of an Atlantic Canada Regional Ocean Observing System (ACROOS).","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127042389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-09-01DOI: 10.1109/OCEANS.2014.7003243
Arnaud Jaegler, Gilles Gaonach
Hydrophones phase and gain dispersions have a deep impact on conventional beampatterns of line arrays, by affecting the sidelobe level. Indeed, high sidelobe levels threaten the detection of weak sources in the presence of strong jammers. Sensors failures are even more critical. Sensors surveillance algorithms are therefore essential to the array performances. They often consist in selecting valid sensors whose power spectral densities are close to a certain estimated mean within a certain fixed or estimated standard deviation. These statistics estimations first take the assumption of no sensors failures, and require parameters settings. After having recalled the impact of sensors dispersions and sensors failures on conventional beampatterns, parameter free sensors surveillance algorithms are proposed. They are based on information criteria, such as Stochastic Complexity Minimization or Akaike Information Criteria. These sensors selection methods are compared to the more traditional methods described above on synthetic data and sea trial signals.
{"title":"Information theory based sensor surveillance","authors":"Arnaud Jaegler, Gilles Gaonach","doi":"10.1109/OCEANS.2014.7003243","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003243","url":null,"abstract":"Hydrophones phase and gain dispersions have a deep impact on conventional beampatterns of line arrays, by affecting the sidelobe level. Indeed, high sidelobe levels threaten the detection of weak sources in the presence of strong jammers. Sensors failures are even more critical. Sensors surveillance algorithms are therefore essential to the array performances. They often consist in selecting valid sensors whose power spectral densities are close to a certain estimated mean within a certain fixed or estimated standard deviation. These statistics estimations first take the assumption of no sensors failures, and require parameters settings. After having recalled the impact of sensors dispersions and sensors failures on conventional beampatterns, parameter free sensors surveillance algorithms are proposed. They are based on information criteria, such as Stochastic Complexity Minimization or Akaike Information Criteria. These sensors selection methods are compared to the more traditional methods described above on synthetic data and sea trial signals.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"248 6","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113972111","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Thermal glider is a new type of underwater glider which harvests its propulsive energy from the thermocline in the ocean. Compared with traditional electric underwater glider, the thermal glider may achieve a much longer duration and range. The heat exchangers on the underwater glider can be mounted above the hull, below the hull, and by the sides of the hull. In this paper, hydrodynamic analysis is conducted for the thermal glider with the three heat exchanger layout designs using computational fluid dynamics. Impact of the layout design on glide efficiency and static stability is investigated, using lift to drag ratio and dimensionless position lever as the evaluation parameters. Result shows that the thermal glider is statically stable with the heat exchangers. The layout of the heat exchangers greatly affects the static stability of the glider, while little influence has been found on the glide efficiency. It is also found that taking glide efficiency and static stability into consideration, the heat exchangers are better mounted below the hull. The result provides theoretical guidance for thermal glider design.
{"title":"Heat exchanger layout for a thermal underwater glider","authors":"Yanan Yang, Yanhui Wang, Zhiliang Wu, Yuhong Liu, Hongwei Zhang, Shuxin Wang","doi":"10.1109/OCEANS.2014.7003274","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003274","url":null,"abstract":"Thermal glider is a new type of underwater glider which harvests its propulsive energy from the thermocline in the ocean. Compared with traditional electric underwater glider, the thermal glider may achieve a much longer duration and range. The heat exchangers on the underwater glider can be mounted above the hull, below the hull, and by the sides of the hull. In this paper, hydrodynamic analysis is conducted for the thermal glider with the three heat exchanger layout designs using computational fluid dynamics. Impact of the layout design on glide efficiency and static stability is investigated, using lift to drag ratio and dimensionless position lever as the evaluation parameters. Result shows that the thermal glider is statically stable with the heat exchangers. The layout of the heat exchangers greatly affects the static stability of the glider, while little influence has been found on the glide efficiency. It is also found that taking glide efficiency and static stability into consideration, the heat exchangers are better mounted below the hull. The result provides theoretical guidance for thermal glider design.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122341997","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-09-01DOI: 10.1109/OCEANS.2014.7003041
Lihong Zhang, V. Mašek, N. Sanatdoost
Underwater/under-ice navigation systems are dependent on the precision of the embedded inertial measurement unit. The performance of MEMS-based gyroscopes, one of the most important inertial sensors, is heavily affected by fabrication imperfection and environmental variation. In this paper we propose and optimize a new mechanical structure for Z-axis tuning-fork gyroscopes along with atmospheric pressure packaging. We have focused on, first, applying gap-varying capacitive sensing method to enhance the sensor resolution, and second, optimizing the design by modifying the location and shape of suspending frame/cantilevers as well as tuning their parameters to make the gyroscope structure more robust against fabrication variation. Our numerical analyses show that the optimized gyroscope structure is more immune to fabrication imperfection, and the proposed sensing structure is able to provide better output capacitance response to external rotation, compared to the previously published work.
{"title":"Design of cost-effective reliable MEMS gyroscopes for underwater/under-ice applications","authors":"Lihong Zhang, V. Mašek, N. Sanatdoost","doi":"10.1109/OCEANS.2014.7003041","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003041","url":null,"abstract":"Underwater/under-ice navigation systems are dependent on the precision of the embedded inertial measurement unit. The performance of MEMS-based gyroscopes, one of the most important inertial sensors, is heavily affected by fabrication imperfection and environmental variation. In this paper we propose and optimize a new mechanical structure for Z-axis tuning-fork gyroscopes along with atmospheric pressure packaging. We have focused on, first, applying gap-varying capacitive sensing method to enhance the sensor resolution, and second, optimizing the design by modifying the location and shape of suspending frame/cantilevers as well as tuning their parameters to make the gyroscope structure more robust against fabrication variation. Our numerical analyses show that the optimized gyroscope structure is more immune to fabrication imperfection, and the proposed sensing structure is able to provide better output capacitance response to external rotation, compared to the previously published work.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122207213","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：