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The ship
Published in Alan E. Branch, Michael Robarts, Branch's Elements of Shipping, 2014
Alan E. Branch, Michael Robarts
Modern tonnage, particularly tankers, container ships and passenger liners, have transverse propulsion units in the bows, and these are termed bow thrusters. A number of vessels have side thrusters situated at the stern of the ship. Both bow and side thrusters are situated on the port and starboard sides. Their purpose is to give greater manoeuvrability in confined waters, e.g. ports, to reduce or eliminate the need for tugs. The rudder which enables the vessel to maintain its course is situated aft. Some ships have an additional rudder in the bows for easier manoeuvrability in port and these are generally found on ferries. A modern development is the Azipull or Azipod propulsion system. Stabilizers are in appearance similar to the fins of a fish, and are fitted to modern passenger liners and container ships to reduce rolling in heavy seas. They are fitted in pairs, and when in use protrude at right angles from the hull, deep below the water line. Their number depends on the size of the vessel. The provision of a bulbous bow can also improve passenger comfort, as it can reduce pitching in heavy seas and has also been provided in tankers, bulk carriers and modern cargo liners to increase speed when in ballast.
Rudder roll damping and ship heading control using a model predictive control algorithm
Published in C. Guedes Soares, Developments in the Collision and Grounding of Ships and Offshore Structures, 2019
H.N. Esfahani, R. Szlapczynski
As a ship motion in ocean environment is taken into account as a resonant system, it deals with a large roll magnitude. The roll motion is regarded as an undesired degree of freedom in a ship. Indeed this induced movement creates an uncomfortable situation for the passengers as well as can lead to damages in a container ship or even to a loss of stability. In order to reduce the roll motion, ships are often equipped with stabilizer systems such as anti-rolling tanks, fin stabilizers and rudder roll stabilizers. The rudder based control system in ship, which is regarded as an under-actuated platform, is commonly used to keep a desired course. Regarding a safe navigation system for ships, plenty researches have been conducted over the past years. Most of them proposed some algorithms in terms of collision avoidance and decision support systems (Perera et al. 2015) and (Perera et al. 2012). However, the role of control algorithms should be also taken into account in designing a safe navigation system. A Rudder Roll Stabilization (RSS) is adopted as a control algorithm to control ship heading and reduce the roll motion simultaneously using one actuator which is called rudder. As for past research on this subject, in (Nicolau et al. 2004), a Fuzzy Rudder-Roll Damping (FRRD) system was designed, which modified the autopilot commands, so that roll damping effects to be obtained, with small rudder angle and rudder rate values. It was shown in (Santoso et al. 2017) that Fuzzy Gain Scheduling (FGS)-PID has more ability to adapt to the environmental changes compared to the conventional PID controller. In (Carletti et al. 2010), a variable structure control algorithm was adopted. A multivariable nonlinear model which regarded the hydrodynamic couplings among sway, roll and yaw due to both the wave effect and the control devices was considered. An optimal path following autopilot with Rudder Roll Reduction (RRR) control was presented in (Wang et al. 2018).
The value of aesthetics in the BIPV roof products segment: a multiperspective study under European market conditions
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2020
In order to derive the comparative data, the study proposed the construction/installation analysis in three scenarios: without the PV installation; with traditional on-roof PV installation BAPV; with BIPV installation. In each scenario, authors assumed the fixed cost (including installation labor) of the basic structure of the roof: roof truss, roof stabilizers, accessories, lift costs, transportation costs, and installation costs. The further cost positions could vary according to the roof composition and the proportion of the roof adapted as the BIPV. In general, authors could enlist the following elements: traditional clay tiles, roof ridge materials, roof insulation materials, and other auxiliary materials. In the case of the BIPV tile scenario, the clay tiles position was replaced in the relative proportion with the solar tile (study assumed 4.95kWp); however, the other elements remained unchanged. One should remember that most of the BIPV tiles could be only installed on the plain roof surface so effectively only clay tiles are to be replaced. The edges of the BIPV tile surface and the roof adjustments were delivered with the help of the dummies; therefore, the material quantity requirements were calculated based on the covered surface deducted from the actual PV tiles part (study assumed 35.3 m2).
Drilling and structural property study of multi-layered fiber and fabric reinforced polymer composite - a review
Published in Materials and Manufacturing Processes, 2019
Yermal Shriraj Rao, Nanjangud Subbarao Mohan, Nagaraja Shetty, Basavannadevaru Shivamurthy
The materials required for critical applications in aircraft, automotive and marine applications have been designed by various researchers using matrix such as metals, ceramics, and polymers.[2] In particular, the fiber/fabric-reinforced polymer (FRP) composites are gaining popularity in the aerospace segment because of high strength-to-weight ratio, noncorrosive, flexibility in design and easy to manufacture compared to other types of composites. The FRP multi-layered composite structures have been used for fuselage and wing skins in aerospace. Manufacturing aircraft structures such as fuselage, wing section, stabilizers, airframes, and engine nacelles demand more fasteners for joining. Alema automation reported that around 60,000 fasteners are essential in airframes of Boeing 777 fuselages. According to those industry reports, a single-engine aircraft requires 10,00,000 drilled holes for joining through fasteners.[3] Several researchers also have reported that more than 60% of the mechanical components fabricated by multi-layered FRP composites are rejected at the initial stage due to poor quality of the drilled hole.[4,5] In the context of conventional drilling on composites, the delamination and the surface roughness, which have a detrimental impact on the structural stiffness and service life of the composites, are the major concern.[6–10] Hence, a great demand arises to develop a high-quality hole for the assembly of structural components.
The Tides of the Zodiac MK VI HD: Comparing the Usability of Inflatable Boats for Seaborne Operations
Published in IISE Transactions on Occupational Ergonomics and Human Factors, 2019
J. Taverniers, J. Suss, G. Delcourt, Y. De Neve
Adequately assessing a product’s usability requires first an accurate description of the product itself, and second its specific context of use (see International Organization for Standardization, 2018; Lancry, 2009; Lewis, 2012). For the current case-study, the Zodiac MK VI HD is a durable, heavy-duty fabric inflatable boat (see Section 2 for physical dimensions), issued with a trimaran hull shape with removable lateral stabilizers. This boat allows for rapid operational (re)deployment and airmobile transport and airdrops, and is designed for optimal maneuverability in challenging conditions. The Zodiac MK VI HD, which is typically fitted with state-of-the-art equipment and accessories, is well-known throughout the world as a Special Operations Forces asset for demanding operations. The boat can carry up to 20 operational combatants (including their gear, equipment, and ammunition) and is suited for a broad range of missions, such as seaborne landings, amphibious search and rescue operations, river-bound or coastal reconnaissance and infiltration, and amphibious evacuations. Given both the variety and importance of these missions, it is reasonable to expect continuous product monitoring and improvement to optimize operational performance and provide maximum safety. Interestingly, on its website the manufacturer (http://zodiacmilpro.com/) claims that the Zodiac MK VI HD’s design and conceptualization is “continually being updated for its ever-changing roles.”