Table 5 - uploaded by Anriëtte Bekker
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The passengers and crew of ships that operate in polar environments often live and work within the confines of these vessels for extended periods. The Requirements for Polar Ships (International Association of Classification Societies, 2011) applies to steel ships that are intended for navigation in ice-infested polar waters. These requirements do...
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... The SA Agulhas II is assigned an intermediate comfort class notation (COMF-V2) for noise and vibration (1 to 100 Hz) by Det Norske Veritas, a Norwegian classification society (Bekker, 2013). The ship can berth 50 crew members and 100 passengers who provide subjective feedback on their perception of ship motion, vibration and noise for the study of human factors. ...
Maritime 4.0 offers technical opportunities to digitally enable ships. Systems are equipped with virtual counterparts, forming cyber-physical systems, to manage operations. However, the human element remains constrained to the physical layer. This dissertation proposes the Mariner 4.0 concept that encourages equipping seafarers with virtual counterparts. Mariner 4.0 is a contribution formulated to serve as a branch of digitalisation that addresses opportunities and challenges associated with human factors in Maritime 4.0, such as a lack in accessibility of human-centric data during operation.
Human cyber-physical systems offer a promising means for human-system integration and human digital representation amidst technically-centred developments. This dissertation contributes an architecture for a human cyber-physical system that defines core elements – a physical layer, where seafarers are present, a cyber layer, which contains virtual counterparts for seafarers, and communication between the layers.
A human cyber-physical system for seafarers is implemented and deployed, which is the first objective of this dissertation. The trialled human cyber-physical system is a contribution that facilitated human-centric data acquisition and processing for seafarers on a ship over the course of a 20-day long voyage. The motion sickness of seafarers is monitored subjectively and objectively in near real time, a novel feat in shipping, in a case study with 63 participants on board. Seafarers recorded their subjective experiences of motion sickness through two methods. The first, traditional method used paper-based questionnaires, while the second, novel method used the human cyber-physical system.
The second objective of this dissertation is to use the human cyber-physical system as a mechanism for advancing the study of motion sickness in shipping. The human cyber-physical system enables personalised data analysis as well as conventional aggregation of results. As such, novel understanding of motion sickness and the study thereof in shipping is uncovered.
Measures of motion exposure are determined objectively according to recommended procedures in ISO 2631-1 (1997) and are integrated with the percentage of motion sick individuals on board, forming motion sickness criteria. The human cyber-physical system provides a platform for inspecting the evolution of criteria development during ship operation. The results contribute diagnostic thresholds that could be used beyond the operational stage to assess the levels of sickness that individuals or a cohort may present if exposed to certain measures of ship motion. The motion sickness criteria accommodates factors, such as exposure duration, for tailoring diagnostic thresholds to voyage missions – potentially applicable for voyage planning and ship design.
The human cyber-physical system provides a customised platform for addressing challenges and opportunities associated with human factors in Maritime 4.0. Moreover, the human cyber-physical system extended the knowledge basis of motion sickness on ships in an innovative manner. The human cyber-physical system served as a human-centric platform for seafarers that empirically revealed the importance of performing data acquisition and analysis at an individual level in addition to an aggregate level.
... Thus, the measurements would be representative of WBV exposure for vessel occupants facing in any direction. The vertical direction was the preferred measurement direction since the vertical acceleration had been confirmed to be dominant in slamming excitation (Bekker, 2013). However, lateral and fore-aft vibration were also significant (Bekker, 2013). ...
... The vertical direction was the preferred measurement direction since the vertical acceleration had been confirmed to be dominant in slamming excitation (Bekker, 2013). However, lateral and fore-aft vibration were also significant (Bekker, 2013). These were not measured, which is a limitation of the present work. ...
This study contributes towards a threshold for the onset of discomfort stemming from vibration that is transmitted to the human body by means of impulsive wave slamming in dynamic shipping environments. Wave slamming is a random, violent, non-linear event. Subjective and objective data were collected from two research voyages on a slamming-prone vessel. Full-scale vertical acceleration measurements were conducted near work and accommodation areas on the vessel. A daily diary survey was used to gather human responses among passengers. In addition, instantaneous slamming vibration comfort ratings were obtained by observers on the ship Bridge during a test sequence that purposefully induced slamming. The results indicate that two different approaches converged to the same VDV 1hr comfort threshold (0. 41 m∕s 1.75 and 0. 43 m∕s 1.75), which corresponds to the limit where 50% of respondents indicated discomfort. A similar analysis using the r. m. s. metric converged to an identical threshold (0. 03 m∕s 2), irrespective of the accumulated time of assessment.
... This would map to the z-axis for standing or seated vessel occupants since most occupants stand or sit for the largest part of the day. Furthermore, this assumption is based on the results by Bekker (2013) that found the vertical direction to be dominant for most vessel operations in ice and open water (Bekker 2013, Mcmahon 2014. ...
... This would map to the z-axis for standing or seated vessel occupants since most occupants stand or sit for the largest part of the day. Furthermore, this assumption is based on the results by Bekker (2013) that found the vertical direction to be dominant for most vessel operations in ice and open water (Bekker 2013, Mcmahon 2014. ...
Ships are designed to operate in harsh conditions, during voyages that can last up to several months. During which passengers are confined to the ship. Consequently, human comfort needs to play a vital role in ship design. However, knowledge in this field is limited in research surrounding human comfort, especially impulsive wave slamming, which is the random impact of waves against the ship hull. The study aims to identify human activities that are most disrupted due to slamming and to statistically determine which metric according to ISO 2631-1 is the most suitable in quantifying human response. Data was obtained by correlating daily surveys of passenger experiences to human vibration metrics from onboard measurements. Results show that sleeping was the activity most affected. There was a strong correlation between the root-mean-square value and ‘daily slam rating’ as well as ‘discomfort incidences’ and a moderate correlation with reports of ‘sleep disturbance’.
... The analysis followed the recommendations of BS ISO 2631-1 [12]. Full details are provided in [13]. The Bridge is an appropriate location to evaluate feedback response in that it can be determined if the Captain receives dynamic queues from the different sources of vibration excitation. ...
Full-scale measurements were performed on the Polar Supply and Research Vessel, the S.A. Agulhas II during ice-trials in the Baltic Sea. Ice loads on the ship hull and propulsion system were measured concurrently with ice-thickness and whole-body vibration comfort for controlled maneuvers in a level ice field. These measurements were aimed at establishing the links between ice-properties, hull-and shaft loads and the vibration feedback received by the operator of the vessel. Results indicate that maneuvers significantly increase the frequency and magnitude of ice loads at the stern shoulder area as well as the ice impacts on the propellers. The number of ice impacts on the instrumented port side shaft line increased for turning maneuvers in a starboard direction. Occupants on the Bridge did not receive feedback through vibration transmission from ice impacts on the hull as a time-history of discrete events. Instead, ice passage excites the global bending modes of the vessel. Blade impacts between ice debris and the propellers are however perceivably transmitted to vessel operators. Although vibration exposure on the bridge is increased by operations in ice subjective experiences of vibration did not reach levels that caused discomfort.
The Requirements for Polar Ships specify the requisites by the International Association of Classification Societies to ensure a safe journey for crew travelling on steel ships that navigate in ice-infested polar waters. One identified problem in these requirements is that they do not yet contain guidelines to direct shipbuilders as to the allowable vibration limits for human vibration exposure. This is attributed to the absence of scientifically reported field research on vibration conditions in human environments gathered when ships break through ice. This study investigated the levels of whole-body vibration exposure associated with open water and ice passage of a Polar Supply and Research Vessel. It was found that occupants are exposed to perceivable vibration for most of the voyage and are likely to experience vibration at levels considered “not uncomfortable”. As a result of high crest factors r.m.s. metrics do not offer a robust means of quantifying in-service ship-borne vibration. In comparison with sailing in calm water, whole-body vibration exposure increased by 21 times in rough open water and up to elevenfold during ice-passage.
