COLREGs-based collision avoidance strategies for unmanned surface vehicles

The aim of this paper is to report the preliminary development of an automatic collision avoidance technique for unmanned marine craft based on standardised rules, COLREGs, defined by the International Maritime Organisation. It is noted that all marine surface vessels are required to adhere to COLREGs at all times in order to minimise or eliminate the risk of collisions. The approach presented is essentially a reactive path planning algorithm which provides feedback to the autopilot of an unmanned vessel or the human captain of a manned ship for steering the craft safely. The proposed strategy consists of waypoint guidance by line-of-sight coupled with a manual biasing scheme. This is applied to the dynamic model of an unmanned surface vehicle. A simple PID autopilot is incorporated to ensure that the vessel adheres to the generated seaway. It is shown through simulations that the resulting scheme is able to generate viable trajectories in the presence of both stationary and dynamic obstacles. Rules 8 and 14 of the COLREGs, which apply to the amount of manoeuvre and to a head-on scenario respectively are simulated. A comparison is also made with an offline or deliberative grid-based path planning algorithm which has been modified to generate COLREGs-compliant routes.

Living in Exospace: ISS and Discovery 1

The concept of exospace, as an alternative liveable structure, is discussed in this article to improve our comprehension of architectural space. Exospace is a man-made space designed for living beyond Earth’s atmosphere. Humankind has developed outerspace technologies to build the International Space Station as a significant experiment in exospace design. The ISS is a new building type for scientific experiments and for testing human existence in outerspace.

A fictional example of exospace, on the other hand, is Discovery 1 spaceship in Stanley Kubrick’s legendary science fiction film 2001: A Space Odyssey (1968). It is a ship travelling to Jupiter with a crew of five astronauts and HAL9000, the artificial intelligence controlling the ship. I will first discuss the ISS, and the space stations built before, from a spatial point of view. A spatial study of Discovery 1 will follow. Finally, through an understanding of exospace, I will return to architectural space with a critical appraisal. The comparison of architectural space with exospace will add to the discussion of space theories from a technological approach.

Exospace creates an alternative reality to architectural space. Architects cannot consider exospaces without comparing them with the spaces they design on Earth. The different context of outerspace shows that a work of terrestrial architecture is very much dependent on its context. A building is not an ‘object’ that can be located anywhere; it is designed for its site. Architectural space is a real, material, continuous, static and extroverted habitable space designed for and used in the specific physical context of Earth. The existence of exospace in science opens a new discussion in architectural theory, both terrestrial and extraterrestrial.

Time-averaged velocity and turbulence intensity at the initial downstream flow from a six-bladed propeller

The current study investigated the time-averaged velocity and turbulence intensity at the initial downstream flow from a six-bladed ship propeller. The six-bladed propeller provided the rapid periodical pulses of thrust in one revolution due to the blades leading to a complex downstream jet. The six-bladed propeller is popular as a boat racing propeller, but the presentation of its flow structure was rarely found in the previous studies. In this study, the experiments were carried out in a water tank to measure the time-averaged velocity and turbulence intensity by using a Laser Doppler Anemometry (LDA) system. The jet was produced by rotating the propeller at a constant speed powered by an electric motor. The maximum tangential and radial velocities of the six-bladed propeller were of 76% and 17% of the maximum axial velocity respectively. The study found that the six-bladed propeller has a lower tangential velocity, but a higher radial velocity with its own diffusing mechanism when comparing to the three-bladed propeller.

Analysis of the 3D zone of flow establishment from a ship’s propeller

In the present study an experimental investigation of the time-averaged velocity and turbulence intensity distributions from a ship’s propeller, in “bollard pull” condition (zero speed of advance), is reported. Previous studies have focused mainly on the velocity profile of not a rotating ship propeller but a plain jet. The velocity profile of a propeller is investigated experimentally in this study.
The velocity measurements were performed in laboratory by using a Laser Doppler Anemometry (LDA). The measurements demonstrated two-peaked ridges velocity profile with a low velocity core at the centre within the near wake. The two-peaked ridges combined to be one-peaked ridge at 3.68 diameters downstream indicating the end of the zone of flow establishment. The study
provides useful information from a rotating ship’s propeller rather than a simplified plain jet to researchers investigating flow velocity generated from a propeller and probably resulting local scouring.

Titans

A large-scale, site-specific play for the opening of the Titanic Belfast building. A shipyard preacher, desperate to be reunited with his wife and daughter, performs an arcane rite on the centenary of the sinking of the Titanic, meeting souls connected with the sinking of the ship.

Supernatural Beliefs, Unconscious Threat and Judgment Bias in Tibetan Buddhists

Individuals who have been subtly reminded of death display heightened in-group favouritism, or “worldview defense.” Terror management theory argues (i) that death cues engender worldview defense via psychological mechanisms specifically evolved to suppress death anxiety, and (ii) that the core function of religiosity is to suppress death anxiety. Thus, terror management theory predicts that extremely religious individuals will not evince worldview defense. Here, two studies are presented in support of an alternative perspective. According to the unconscious vigilance hypothesis, subtly processed threats (which need not pertain to death) heighten sensitivity to affectively valenced stimuli (which need not pertain to cultural attitudes). From this perspective, religiosity mitigates the influence of mortality-salience only insofar as afterlife doctrines reduce the perceived threat posed by death. Tibetan Buddhism portrays death as a perilous gateway to rebirth rather than an end to suffering; faith in this doctrine should therefore not be expected to nullify mortality-salience effects. In Study 1, devout Tibetan Buddhists who were subtly reminded of death produced exaggerated aesthetic ratings unrelated to cultural worldviews. In Study 2, devout Tibetan Buddhists produced worldview defense following subliminal exposure to non-death cues of threat. The results demonstrate both the domain-generality of the process underlying worldview defense and the importance of religious doctrinal content in moderating mortality-salience effects.

The prediction of process-induced deformation in a thermoplastic composite in support of manufacturing simulation

Digital manufacturing techniques can simulate complex assembly sequences using computer-aided design-based, as-designed' part forms, and their utility has been proven across several manufacturing sectors including the ship building, automotive and aerospace industries. However, the reality of working with actual parts and composite components, in particular, is that geometric variability arising from part forming or processing conditions can cause problems during assembly as the as-manufactured' form differs from the geometry used for any simulated build validation. In this work, a simulation strategy is presented for the study of the process-induced deformation behaviour of a 90 degrees, V-shaped angle. Test samples were thermoformed using pre-consolidated carbon fibre-reinforced polyphenylene sulphide, and the processing conditions were re-created in a virtual environment using the finite element method to determine finished component angles. A procedure was then developed for transferring predicted part forms from the finite element outputs to a digital manufacturing platform for the purpose of virtual assembly validation using more realistic part geometry. Ultimately, the outcomes from this work can be used to inform process condition choices, material configuration and tool design, so that the dimensional gap between as-designed' and as-manufactured' part forms can be reduced in the virtual environment.

Exhibiting Maritime Histories: Titanic Belfast in the Post-Conflict City

The sinking of the RMS Titanic in 1912 represents one of the most infamous maritime disasters in the history of shipping. Yet despite it entering the public imagination in the decades after its sinking, until recently it has all but been erased from the collective memory of the people of Belfast, the city in which it was built. In a post-conflict context, however, Belfast has begun to re-imagine the role of the ship in the city’s history, most particularly in the re-development of the docklands area and its designation as the Titanic Quarter, and through its landmark project the Titanic Belfast museum. This paper will trace the economic, social and political context from which the Titanic was built, and the role that this played in silencing any very public commemoration of its sinking until after the signing of the Belfast Agreement. The ‘story’ told in the new museum will be analysed from this perspective and will illustrate how the wounds of the Troubles continue to inform the interpretation of the city’s divided past.

Determining optimal duration of seed translocation periods for benthic mussel (Mytilus edulis) cultivation using physiological and behavioural measures of stress

During the benthic cultivation process of Mytilus edulis (blue mussels), wild mussel seed is often transplanted from naturally occurring subtidal beds to sheltered in-shore waters to be grown to a commercial size. The survival of these relaid mussels is ultimately a function of their quality and physiological condition upon relaying and it has been recognised that mussels can suffer from a loss in condition following transportation. We investigated whether the process of being transported to ongrowing plots had a negative effect on the physiological health and resultant behaviour of mussels by simulating transportation conditions in a controlled experiment. Mussels were kept, out of water, in plastic piping to recreate translocation conditions and further, we tested if depth held in a ship hold (0, 1.5 and 3 m) and length of time emersed (12, 24 and 48 h) affected mussel condition and behaviour. Physiological condition was assessed by quantifying mussel tissue pH and whole tissue glucose, glycogen, succinate and propionate concentrations. The rate of byssogenesis was also quantified to estimate recovery following a period of re-immersion. The depth at which mussels were held did not affect any of the physiological indicators of mussel stress but short-term byssus production was affected. Mussels held at 3 m produced fewer byssus threads during the first 72 h following re-immersion compared with mussels at 0 m (i.e. not buried) suggesting that depth held can impede recovery following transportation. Duration of emersion affected all stress indicators. Specifically, mussels held out of water for 48 h had a reduced physiological condition compared with those emersed for just 12 h. This work has practical implications for the benthic cultivation industry and based on these results we recommend that mussels are held out of water for less than 24 h prior to relaying to ensure physiological health and resultant condition is preserved.

The Vertical Distribution and Evolution of Slam Pressure on an Oscillating Wave Surge Converter

The accurate definition of the extreme wave loads which act on offshore structures represents a significant challenge for design engineers and even with decades of empirical data to base designs upon there are still failures attributed to wave loading. The environmental conditions which cause these loads are infrequent and highly non-linear which means that they are not well understood or simple to describe. If the structure is large enough to affect the incident wave significantly further non-linear effects can influence the loading. Moreover if the structure is floating and excited by the wave field then its responses, which are also likely to be highly non-linear, must be included in the analysis. This makes the description of the loading on such a structure difficult to determine and the design codes will often suggest employing various tools including small scale experiments, numerical and analytical methods, as well as empirical data if available.
Wave Energy Converters (WECs) are a new class of offshore structure which pose new design challenges, lacking the design codes and empirical data found in other industries. These machines are located in highly exposed and energetic sites, designed to be excited by the waves and will be expected to withstand extreme conditions over their 25 year design life. One such WEC is being developed by Aquamarine Power Ltd and is called Oyster. Oyster is a buoyant flap which is hinged close to the seabed, in water depths of 10 to 15m, piercing the water surface. The flap is driven back and forth by the action of the waves and this mechanical energy is then converted to electricity.
It has been identified in previous experiments that Oyster is not only subject to wave impacts but it occasionally slams into the water surface with high angular velocity. This slamming effect has been identified as an extreme load case and work is ongoing to describe it in terms of the pressure exerted on the outer skin and the transfer of this short duration impulsive load through various parts of the structure.
This paper describes a series of 40th scale experiments undertaken to investigate the pressure on the face of the flap during the slamming event. A vertical array of pressure sensors are used to measure the pressure exerted on the flap. Characteristics of the slam pressure such as the rise time, magnitude, spatial distribution and temporal evolution are revealed. Similarities are drawn between this slamming phenomenon and the classical water entry problems, such as ship hull slamming. With this similitude identified, common analytical tools are used to predict the slam pressure which is compared to that measured in the experiment.

Deliberative Democracy in Northern Ireland: Opportunities and challenges for consensus in a consociational system

The 1998 Multiparty Agreement established a consociational system that contains within it an explicit dualism: unionist/nationalist, north and south of Ireland, and British and Irish. But although this formula has facilitated relatively stable and devolved governance, it is based on a distorted representation of a society in which there are much more complex divisions and, indeed, many common problems. Citizen-led efforts towards deliberative democracy since the 1980s have demonstrated both the will and the capacity for alternative, consensual political expressions. This chapter examines the challenges and opportunities facing these citizen-led initiatives in a political environment which, despite the significant decline in violence and terror, seems stubbornly resistant to the idea of broadening the various means of democratic participation.

Inactivating mutations in an SH2 domain-encoding gene in X-linked lymphoproliferative syndrome

X-linked lymphoproliferative syndrome (XLP) is an inherited immunodeficiency characterized by increased susceptibility to Epstein-Barr virus (EBV). In affected males, primary EBV infection leads to the uncontrolled proliferation of virus-containing B cells and reactive cytotoxic T cells, often culminating in the development of high-grade lymphoma. The XLP gene has been mapped to chromosome band Xq25 through linkage analysis and the discovery of patients harboring large constitutional genomic deletions. We describe here the presence of small deletions and intragenic mutations that specifically disrupt a gene named DSHP in 6 of 10 unrelated patients with XLP. This gene encodes a predicted protein of 128 amino acids composing a single SH2 domain with extensive homology to the SH2 domain of SHIP, an inositol polyphosphate 5-phosphatase that functions as a negative regulator of lymphocyte activation. DSHP is expressed in transformed T cell lines and is induced following in vitro activation of peripheral blood T lymphocytes. Expression of DSHP is restricted in vivo to lymphoid tissues, and RNA in situ hybridization demonstrates DSHP expression in activated T and B cell regions of reactive lymph nodes and in both T and B cell neoplasms. These observations confirm the identity of DSHP as the gene responsible for XLP, and suggest a role in the regulation of lymphocyte activation and proliferation. Induction of DSHP may sustain the immune response by interfering with SHIP-mediated inhibition of lymphocyte activation, while its inactivation in XLP patients results in a selective immunodeficiency to EBV.

Violence against women in the Irish War of Independence, 1919-1921

This chapter examines the nature and extent of violence experienced by women in Ireland during the Irish War of Independence (1919-1921) at the hands of both the Crown forces and the Irish Republican Army. It argues that targetted killings of women by either side was rare. The most common forms of such violence can be categorised as physical, gendered (cutting of hair) and psychological (intimidation and the killing of male relatives). It argues that there was a difference between gendered and sexual crime, the latter of which appears to have been very uncommon. A considerable part of the chapter uses theoretical literature on violence against women in conflict zones to explain why sexual violence was uncommon, arguing that neither side had much to gain from its employment, that the Crown forces were aware of the damage it could do to Britain's international reputation and that the terror tactics adopted by the Crown forces were sufficient to achieve their ends without resorting to rape. In regard to the IRA, the absence of any evidence of rape or sexual assault being perpetrated could be attributable to their Catholicism, reliance on support from the community, the efforts of the first Dáil to achieve foreign recognition of the Republic and the role of Cumann na mBan women in the guerrilla conflict. The historiography of women in the Irish revolution is also analysed.