Comparison of diesel-electric with hybrid-electric propulsion system safety using system-theoretic process analysis

Cruise ship industry is rapidly developing, with both the vessels size and number constantly growing up, which renders ensuring passengers, crew and ship safety a paramount necessity. Collision, grounding and fire are among the most frequent accidents on cruise ships with high consequences. In this study, a hazard analysis of diesel-electric and hybrid-electric propulsion system is undertaken using System-Theoretic Process Analysis (STPA). The results demonstrate significant increase in potential hazardous scenarios due to failures in automation and control systems, leading to fire and a higher number of scenarios leading to propulsion and power loss in hybrid-electric propulsion systems than on a conventional cruise-ship propulsion system. Results also demonstrate that STPA enhancement is required to compare the risk of two propulsion systems

Gaining insight into safety culture maturity levels in shipping organizations : questionnaires vs key performance indicators

Safety is of the utmost importance in the maritime industry and shipping organizations are looking for means to continuously improve their safety performances. It has also been dictated by the ISM Code that shipping companies need to implement an “effective safety culture”. Therefore, shipping companies are trying to identify the areas which require further improvements to reach to the desired level of safety within their organizations. Safety culture surveys, interviews and observations are introduced to gain insight into company safety culture maturity levels in shipping, but yet, there is no an available industry wide benchmark for shipping companies in order to determine their current status within the industry and improve their safety culture maturity levels accordingly. The aim of this study is to develop a benchmark for the safety climate questionnaires amongst the shipping companies where they can compare their safety performance data with other shipping companies according to significant safety attributes/dimensions. This study is a part of the overall safety culture assessment and implementation framework which described briefly in the following sections. The overall framework aims to assess the current safety culture maturity level in a company and develop action plans to improve identified vulnerable areas

Automatic traffic scenarios generation for autonomous ships collision avoidance system testing

The Collision Avoidance (CA) system constitutes a key enabling technology for the Maritime Autonomous Surface Ships (MASS), the appropriate functionality of which is critical for assuring the navigation safety. Although several techniques including testing of the collision scenarios in a virtual environment can be employed, the trust of testing phase results depends on the number of tested scenarios and their coverage. This study aims at proposing a systematic and automatic process for the generation of the traffic scenarios that can be employed for the CA system testing. First, the range of the investigated parameters is defined, and samples of potential traffic parameters are generated using Sobol sequences. Subsequently, hazardous traffic scenarios are identified from the initially generated scenarios by using predefined rules. For these hazardous scenarios, a risk vector considering weather conditions and traffic conditions is calculated. A clustering algorithm is employed to identify the groups of traffic conditions that can be encountered based on each scenario risk vector and COLREGs traffic scenarios. For each of these groups, the riskiest scenario is provided as input for the test cases development, thus, simplifying the selection process of testing scenarios. The process is applied to a theoretical Short Sea Shipping autonomous vessel, whereas the derived results are employed to discuss the advantages and disadvantages of the developed process

Paving the way toward autonomous shipping development for European Waters – The AUTOSHIP project

New developments in maritime industry include the design and operation of autonomous ships. The AUTOSHIP project is one initiative promoting the use of autonomous ships in European waters focusing on two specific use cases, a Short Sea Shipping (SSS) cargo vessel and an Inland Waterways (IWW) barge. The AUTOSHIP objectives include thorough regulatory, societal, financial, safety and security analyses for the two investigated use cases as well as the development of a novel framework and methods for the design of autonomous vessels. This objective is achieved with the support of a number of activities, including supply chain, regulatory, risk and gaps analyses. Some results and findings from these activities are presented in this paper. The results demonstrate that the supply chain analysis is important to understand the complex relationships between different partners and phases for the effective design of maritime autonomous systems. Furthermore, a number of regulatory gaps needs to be addressed for the wider adoption of the AUTOSHIP use cases. There is a number of essential hazards associated with each of the two use cases; measures to mitigate these hazards are presented

Dynamic Blackout Probability Monitoring System for Cruise Ship Power Plants

Stringent environmental regulations and efforts to improve the shipping operations sustainability have resulted in designing and employing more complex configurations for the ship power plants systems and the implementation of digitalised functionalities. Due to these systems complexity, critical situations arising from the components and subsystem failures, which may lead to accidents, require timely detection and mitigation. This study aims at enhancing the safety of ship complex systems and their operation by developing the concept of an integrated monitoring safety system that employs existing safety models and data fusion from shipboard sensors. Detailed Fault Trees that model the blackout top event, representing the sailing modes of a cruise ship and the operating modes of its plant, are employed. Shipboard sensors’ measurements acquired by the cruise ship alarm and monitoring system are integrated with these Fault Trees to account for the acquired shipboard information on the investigated power plant configuration and its components operating conditions, thus, facilitating the estimation of the blackout probability time variation as well as the dynamic criticality assessment of the power plant components. The proposed concept is verified by using a virtual simulation environment developed in Matlab/Simulink. This study supports the dynamic assessment of the ship power plants and therefore benefits the decision-making for enhancing the plant safety during operations

Dissociable effects of 5-HT2C receptor antagonism and genetic inactivation on perseverance and learned non-reward in an egocentric spatial reversal task

Cognitive flexibility can be assessed in reversal learning tests, which are sensitive to modulation of 5-HT2C receptor (5-HT2CR) function. Successful performance in these tests depends on at least two dissociable cognitive mechanisms which may separately dissipate associations of previous positive and negative valence. The first is opposed by perseverance and the second by learned non-reward. The current experiments explored the effect of reducing function of the 5-HT2CR on the cognitive mechanisms underlying egocentric reversal learning in the mouse. Experiment 1 used the 5-HT2CR antagonist SB242084 (0.5 mg/kg) in a between-groups serial design and Experiment 2 used 5-HT2CR KO mice in a repeated measures design. Animals initially learned to discriminate between two egocentric turning directions, only one of which was food rewarded (denoted CS+, CS−), in a T- or Y-maze configuration. This was followed by three conditions; (1) Full reversal, where contingencies reversed; (2) Perseverance, where the previous CS+ became CS− and the previous CS− was replaced by a novel CS+; (3) Learned non-reward, where the previous CS− became CS+ and the previous CS+ was replaced by a novel CS-. SB242084 reduced perseverance, observed as a decrease in trials and incorrect responses to criterion, but increased learned non-reward, observed as an increase in trials to criterion. In contrast, 5-HT2CR KO mice showed increased perseverance. 5-HT2CR KO mice also showed retarded egocentric discrimination learning. Neither manipulation of 5-HT2CR function affected performance in the full reversal test. These results are unlikely to be accounted for by increased novelty attraction, as SB242084 failed to affect performance in an unrewarded novelty task. In conclusion, acute 5-HT2CR antagonism and constitutive loss of the 5-HT2CR have opposing effects on perseverance in egocentric reversal learning in mice. It is likely that this difference reflects the broader impact of 5HT2CR loss on the development and maintenance of cognitive function

A methodology to define risk matrices–application to inland water ways autonomous ships

The autonomous ships’ introduction is associated with a number of challenges including the lack of appropriate risk acceptance criteria to support the risk assessment process during the initial design phases. This study aims to develop a rational methodology for selecting appropriate risk matrix ratings, which are required to perform the risk assessment of autonomous and conventional ships at an early design stage. This methodology consists of four phases and employs the individual and societal risk acceptance criteria to determine the risk matrix ratings for the groups of people exposed to risks. During the first and second phase, the required input parameters for the risk matrix ratings based on the individual risk and societal risk are calculated, respectively. During the third phase, the risk matrix ratings are defined using input from the first and second phases. During the fourth phase, the equivalence between the different types of consequences is specified. The methodology is applied for the case study of a crewless inland waterways ship to assess her typical operation within north-European mainland. The results demonstrate that the inclusion of societal risk resulted in more stringent risk matrix ratings compared to the ones employed in previous studies. Moreover, the adequacy of the proposed methodology and its effectiveness to provide risk acceptance criteria aligned with societal and individual risk acceptance criteria as well as its applicability to conventional ships are discussed

SEAHORSE procedure improvement system : development of instrument

Standard Operating Procedures (SOPs) have been used in almost every sector in order to improve operational safety and efficiency. The situation is not different in maritime sector, where SOPs are enforced through the regulatory framework in order to achieve safer shipping operations. Even though it is a regulatory requirement to develop and implement SOPs, it can be seen that during shipping operations these procedures are not followed due to various reasons. It was observed that one of the most common reasons for not following an SOP is due to poorly designed procedures, which are impractical, unclear or sometimes factually wrong. Therefore, these poorly designed procedures are disregarded by crewmembers, which not only prevent the practical implementation of SOP’s during shipping operations but also devalue the importance of using SOPs. Therefore, it is of key importance that a systematic approach is needed to identify and improve the current SOP’s as well as preventing potentially harmful workarounds. The EU FP7 SEAHORSE project is developing a “Procedure Improvement System” which can be actively used by the crewmembers any time anonymously. In order to achieve this, a comprehensive questionnaire has been developed and used to collect data from seafarers across Europe where they were asked to report on impractical SOPs and common workarounds conducted on board ships. This paper presents the instrument and initial results

Thalamic inputs to dorsomedial striatum are involved in inhibitory control: evidence from the five-choice serial reaction time task in rats

Rationale Corticostriatal circuits are widely implicated in the top-down control of attention including inhibitory control and behavioural flexibility. However, recent neurophysiological evidence also suggests a role for thalamic inputs to striatum in behaviours related to salient, reward-paired cues. Objectives Here, we used designer receptors exclusively activated by designer drugs (DREADDs) to investigate the role of parafascicular (Pf) thalamic inputs to the dorsomedial striatum (DMS) using the five-choice serial reaction time task (5CSRTT) in rats. Methods The 5CSRTT requires sustained attention in order to detect spatially and temporally distributed visual cues and provides measures of inhibitory control related to impulsivity (premature responses) and compulsivity (perseverative responses). Rats underwent bilateral Pf injections of the DREADD vector, AAV2-CaMKIIa-HA-hM4D(Gi)-IRES-mCitrine. The DREADD agonist, clozapine N-oxide (CNO; 1 μl bilateral; 3 μM) or vehicle, was injected into DMS 1 h before behavioural testing. Task parameters were manipulated to increase attention load or reduce stimulus predictability respectively. Results We found that inhibition of the Pf-DMS projection significantly increased perseverative responses when stimulus predictability was reduced but had no effect on premature responses or response accuracy, even under increased attentional load. Control experiments showed no effects on locomotor activity in an open field. Conclusions These results complement previous lesion work in which the DMS and orbitofrontal cortex were similarly implicated in perseverative responses and suggest a specific role for thalamostriatal inputs in inhibitory control

Markers of serotonergic function in the orbitofrontal cortex and dorsal raphé nucleus predict individual variation in spatial-discrimination serial reversal learning.

Dysfunction of the orbitofrontal cortex (OFC) impairs the ability of individuals to flexibly adapt behavior to changing stimulus-reward (S-R) contingencies. Impaired flexibility also results from interventions that alter serotonin (5-HT) and dopamine (DA) transmission in the OFC and dorsomedial striatum (DMS). However, it is unclear whether similar mechanisms underpin naturally occurring variations in behavioral flexibility. In the present study, we used a spatial-discrimination serial reversal procedure to investigate interindividual variability in behavioral flexibility in rats. We show that flexibility on this task is improved following systemic administration of the 5-HT reuptake inhibitor citalopram and by low doses of the DA reuptake inhibitor GBR12909. Rats in the upper quintile of the distribution of perseverative responses during repeated S-R reversals showed significantly reduced levels of the 5-HT metabolite, 5-hydroxy-indoleacetic acid, in the OFC. Additionally, 5-HT2A receptor binding in the OFC of mid- and high-quintile rats was significantly reduced compared with rats in the low-quintile group. These perturbations were accompanied by an increase in the expression of monoamine oxidase-A (MAO-A) and MAO-B in the lateral OFC and by a decrease in the expression of MAO-A, MAO-B, and tryptophan hydroxylase in the dorsal raphé nucleus of highly perseverative rats. We found no evidence of significant differences in markers of DA and 5-HT function in the DMS or MAO expression in the ventral tegmental area of low- vs high-perseverative rats. These findings indicate that diminished serotonergic tone in the OFC may be an endophenotype that predisposes to behavioral inflexibility and other forms of compulsive behavior.This work was supported by Medical Research Council Grants (G0701500; G0802729), a 503 Wellcome Trust Programme Grant (grant number 089589/Z/09/Z), and by a Core Award 504 from the Medical Research Council and the Wellcome Trust to the Behavioural and Clinical 505 21 Neuroscience Institute (MRC Ref G1000183; WT Ref 093875/Z/10/Z). RLB was supported 506 by a studentship from the Medical Research Council. JA was supported by a Fellowship from 507 the Swedish Research Council (350-2012-230). BJ was supported by Fellowships from the 508 AXA Research Fund and the National Health and Medical Research Council of Australia. 509 Financial support from the Fredrik and Ingrid Thuring Foundation is also acknowledged.This is the accepted manuscript. The final version is available from Nature Publishing at http://www.nature.com/npp/journal/vaop/ncurrent/full/npp2014335a.html