Academic literature on the topic 'Centre bowl friction'

This research is part of a larger project to investigate the wear and friction of the centre bearing of a rail freight truck. Existing centre bearing surfaces include flame hardened AISI 1030 steel and AISI 1053 cast steel top centres mating against un-greased and/or greased Hadfield steel centre bowl liners, and polyethylene centre bowl liners. The wear life of the unlubricated steels against Hadfield steel is short, greasing the bearings is costly, and industry reports some failures of polyethylene centre bowl liners due to excessive plastic flow and cracking of the rim wall.

The article discusses the use of pivot bearing friction liners, made of selected materials, in railway freight wagons’ spherical centre bowls. Comparative studies on the effect of suspension dynamics on the equivalent stresses in the liner material were carried out using the finite element method and multibody simulation. The results show the magnitude and location of the highest stresses in the liner with varying input loads, friction coefficients and interacting materials. The analysis is a basis for a simulation method for predicting the fatigue life of the suspension friction liner placed in the centre bowl between the bogie frame and the vehicle body.

Currently, great attention is paid to the development issue of the shelf’s fuel and energy resources foremost in the oil-gas fields of the Caspian Sea. The problem solution requires the studying of great majority of scientific-technical issues. One of the significant problems is the lead-out of steel jacket from the offshore platform as a major element of oil-gas field hydro-technical facilities meant for the operation in the deep water. The calculations for the execution of operations with steel jacket of deep stationary platform from the block with the detailed chara- cteristics by the mass and gravity center coordinates alongside line data have been carried out with “SACS” and “STAAD.PRO” software programs. The steel jacket is pushed astern with the push-pull equipment on the barge. Due to the shift of gravity centre the jacket changes the trim in the stern. Through the elevation of trim angle brought in alignment with the friction ration between the jacket and barge, the jacket slides further itself. Herewith, the trim increases until the gravity centre of steel jacket on the barge is not in alignment with rotation centre of the large rocker arms. The studies helped to fix the position of the jacket’s gravity centre from the aft perpendicular, the trim moment, the trim of the barge, the draft with the bow and stern and the trim angle as well.

Abstract The University of Massachusetts W- and X-band, mobile, Doppler radars scanned several tornadoes at close range in south-central Kansas on 12 May 2004. The detailed vertical structure of the Doppler wind and radar reflectivity fields of one of the tornadoes is described with the aid of boresighted video. The inside wall of a weak-echo hole inside the tornado was terminated at the bottom as a bowl-shaped boundary within several tens of meters of the ground. Doppler signatures of horizontal vortices were noted along one edge in the lowest 500 m of the tornado. The vertical structure of Doppler velocity displayed significant variations on the 100-m scale. Near the center of the tornado, a quasi-horizontal, radial bulge of the weak-echo hole at ∼500–600 m AGL dropped to about 400 m above the ground and was evident as a weak-echo band to the south of the tornado. It is suggested that this feature represents echo-weak material transported radially outward by a vertical circulation. Significant vertical variations of Doppler velocity were found in the surface friction layer both inside and outside the tornado core. The shape of a weak-echo notch that was associated with a hook echo wrapped around the tornado is described. Highest Doppler velocities were located outside the condensation funnel. The structure of the other tornadoes is also described, but with much less detail. Some of the analyses are compared with numerical simulations of tornado-like vortices done elsewhere.

An increase in the operational reliability of friction units of railway transport by applying antifriction combined coatings formed by electrospark alloying, which ensures their greater strength and adhesion to metal, is considered. Keywords: electrospark alloying combined antifriction coating, strength, adhesion. alekc_sap@mail.ru

In 1988, historian Nadia Wheatley and indigenous artist Donna Rawlins published their award-winning picture book, My Place, a reinterpretation of Australian national identity and sovereignty prompted by the bicentennial of white settlement. Twenty years later, the Australian Broadcasting Corporation (ABC) commissioned Penny Chapman’s multi-platform project based on this book. The 13 episodes of the television series begin in 2008, each telling the story of a child at a different point in history, and are accompanied by substantial interactive online content. Issues as diverse as religious difference and immigration, wartime conscription and trauma, and the experiences of Aboriginal Australians are canvassed. The program itself, which has a second series currently in production, introduces child audiences to—and implicates them in—a rich ideological fabric of deeply politicised issues that directly engage with vexed questions of Australian nationhood. The series offers a subversive view of Australian history and society, and it is the child—whether protagonist on the screen or the viewer/user of the content—who is left to discover, negotiate and move beyond often problematic societal norms. As one of the public broadcaster’s keystone projects, My Place signifies important developments in ABC’s construction of multicultural child citizenship. The digitisation of Australian television has facilitated a wave of multi-channel and new media innovation. Though the development of a multi-channel ecology has occurred significantly later in Australia than in the US or Europe, in part due to genre restrictions on broadcasters, all major Australian networks now have at least one additional free-to-air channel, make some of their content available online, and utilise various forms of social media to engage their audiences. The ABC has been in the vanguard of new media innovation, leveraging the industry dominance of ABC Online and its cross-platform radio networks for the repurposing of news, together with the additional funding for digital renewal, new Australian content, and a digital children’s channel in the 2006 and 2009 federal budgets. In line with “market failure” models of broadcasting (Born, Debrett), the ABC was once the most important producer-broadcaster for child viewers. With the recent allocation for the establishment of ABC3, it is now the catalyst for a significant revitalisation of the Australian children’s television industry. The ABC Charter requires it to broadcast programs that “contribute to a sense of national identity” and that “reflect the cultural diversity of the Australian community” (ABC Documents). Through its digital children’s channel (ABC3) and its multi-platform content, child viewers are not only exposed to a much more diverse range of local content, but also politicised by an intricate network of online texts connected to the TV programs. The representation of diasporic communities through and within multi-platformed spaces forms a crucial part of the way(s) in which collective identities are now being negotiated in children’s texts. An analysis of one of the ABC’s My Place “projects” and its associated multi-platformed content reveals an intricate relationship between postcolonial concerns and the construction of child citizenship. Multicultural Places, Multi-Platformed Spaces: New Media Innovation at the ABC The 2007 restructure at the ABC has transformed commissioning practices along the lines noted by James Bennett and Niki Strange of the BBC—a shift of focus from “programs” to multi-platform “projects,” with the latter consisting of a complex network of textual production. These “second shift media practices” (Caldwell) involve the tactical management of “user flows structured into and across the textual terrain that serve to promote a multifaceted and prolonged experience of the project” (Bennett and Strange 115). ABC Managing Director Mark Scott’s polemic deployment of the “digital commons” trope (Murdock, From) differs from that of his opposite number at the BBC, Mark Thompson, in its emphasis on the glocalised openness of the Australian “town square”—at once distinct from, and an integral part of, larger conversations. As announced at the beginning of the ABC’s 2009 annual report, the ABC is redefining the town square as a world of greater opportunities: a world where Australians can engage with one another and explore the ideas and events that are shaping our communities, our nation and beyond … where people can come to speak and be heard, to listen and learn from each other. (ABC ii)The broad emphasis on engagement characterises ABC3’s positioning of children in multi-platformed projects. As the Executive Producer of the ABC’s Children’s Television Multi-platform division comments, “participation is very much the mantra of the new channel” (Glen). The concept of “participation” is integral to what has been described elsewhere as “rehearsals in citizenship” (Northam). Writing of contemporary youth, David Buckingham notes that “‘political thinking’ is not merely an intellectual or developmental achievement, but an interpersonal process which is part of the construction of a collective, social identity” (179). Recent domestically produced children’s programs and their associated multimedia applications have significant potential to contribute to this interpersonal, “participatory” process. Through multi-platform experiences, children are (apparently) invited to construct narratives of their own. Dan Harries coined the term “viewser” to highlight the tension between watching and interacting, and the increased sense of agency on the part of audiences (171–82). Various online texts hosted by the ABC offer engagement with extra content relating to programs, with themed websites serving as “branches” of the overarching ABC3 metasite. The main site—strongly branded as the place for its targeted demographic—combines conventional television guide/program details with “Watch Now!,” a customised iView application within ABC3’s own themed interface; youth-oriented news; online gaming; and avenues for viewsers to create digital art and video, or interact with the community of “Club3” and associated message boards. The profiles created by members of Club3 are moderated and proscribe any personal information, resulting in an (understandably) restricted form of “networked publics” (boyd 124–5). Viewser profiles comprise only a username (which, the website stresses, should not be one’s real name) and an “avatar” (a customisable animated face). As in other social media sites, comments posted are accompanied by the viewser’s “name” and “face,” reinforcing the notion of individuality within the common group. The tool allows users to choose from various skin colours, emphasising the multicultural nature of the ABC3 community. Other customisable elements, including the ability to choose between dozens of pre-designed ABC3 assets and feeds, stress the audience’s “ownership” of the site. The Help instructions for the Club3 site stress the notion of “participation” directly: “Here at ABC3, we don’t want to tell you what your site should look like! We think that you should be able to choose for yourself.” Multi-platformed texts also provide viewsers with opportunities to interact with many of the characters (human actors and animated) from the television texts and share further aspects of their lives and fictional worlds. One example, linked to the representation of diasporic communities, is the Abatti Pizza Game, in which the player must “save the day” by battling obstacles to fulfil a pizza order. The game’s prefacing directions makes clear the ethnicity of the Abatti family, who are also visually distinctive. The dialogue also registers cultural markers: “Poor Nona, whatsa she gonna do? Now it’s up to you to help Johnny and his friends make four pizzas.” The game was acquired from the Canadian-animated franchise, Angela Anaconda; nonetheless, the Abatti family, the pizza store they operate and the dilemma they face translates easily to the Australian context. Dramatisations of diasporic contributions to national youth identities in postcolonial or settler societies—the UK (My Life as a Popat, CITV) and Canada (How to Be Indie)—also contribute to the diversity of ABC3’s television offerings and the positioning of its multi-platform community. The negotiation of diasporic and postcolonial politics is even clearer in the public broadcaster’s commitment to My Place. The project’s multifaceted construction of “places,” the ethical positioning of the child both as an individual and a member of (multicultural) communities, and the significant acknowledgement of ongoing conflict and discrimination, articulate a cultural commons that is more open-ended and challenging than the Eurocentric metaphor, the “town square,” suggests. Diversity, Discrimination and Diasporas: Positioning the Viewser of My Place Throughout the first series of My Place, the experiences of children within different diasporic communities are the focal point of five of the initial six episodes, the plots of which revolve around children with Lebanese, Vietnamese, Greek, and Irish backgrounds. This article focuses on an early episode of the series, “1988,” which explicitly confronts the cultural frictions between dominant Anglocentric Australian and diasporic communities. “1988” centres on the reaction of young Lily to the arrival of her cousin, Phuong, from Vietnam. Lily is a member of a diasporic community, but one who strongly identifies as “an Australian,” allowing a nuanced exploration of the ideological conflicts surrounding the issue of so-called “boat people.” The protagonist’s voice-over narration at the beginning of the episode foregrounds her desire to win Australia’s first Olympic gold medal in gymnastics, thus mobilising nationally identified hierarchies of value. Tensions between diasporic and settler cultures are frequently depicted. One potentially reactionary sequence portrays the recurring character of Michaelis complaining about having to use chopsticks in the Vietnamese restaurant; however, this comment is contextualised several episodes later, when a much younger Michaelis, as protagonist of the episode “1958,” is himself discriminated against, due to his Greek background. The political irony of “1988” pivots on Lily’s assumption that her cousin “won’t know Australian.” There is a patronising tone in her warning to Phuong not to speak Vietnamese for fear of schoolyard bullying: “The kids at school give you heaps if you talk funny. But it’s okay, I can talk for you!” This encourages child viewers to distance themselves from this fictional parallel to the frequent absence of representation of asylum seekers in contemporary debates. Lily’s assumptions and attitudes are treated with a degree of scepticism, particularly when she assures her friends that the silent Phuong will “get normal soon,” before objectifying her cousin for classroom “show and tell.” A close-up camera shot settles on Phuong’s unease while the children around her gossip about her status as a “boat person,” further encouraging the audience to empathise with the bullied character. However, Phuong turns the tables on those around her when she reveals she can competently speak English, is able to perform gymnastics and other feats beyond Lily’s ability, and even invents a story of being attacked by “pirates” in order to silence her gossiping peers. By the end of the narrative, Lily has redeemed herself and shares a close friendship with Phuong. My Place’s structured child “participation” plays a key role in developing the postcolonial perspective required by this episode and the project more broadly. Indeed, despite the record project budget, a second series was commissioned, at least partly on the basis of the overwhelmingly positive reception of viewsers on the ABC website forums (Buckland). The intricate My Place website, accessible through the ABC3 metasite, generates transmedia intertextuality interlocking with, and extending the diegesis of, the televised texts. A hyperlinked timeline leads to collections of personal artefacts “owned” by each protagonist, such as journals, toys, and clothing. Clicking on a gold medal marked “History” in Lily’s collection activates scrolling text describing the political acceptance of the phrase “multiculturalism” and the “Family Reunion” policy, which assisted the arrival of 100,000 Vietnamese immigrants. The viewser is reminded that some people were “not very welcoming” of diasporic groups via an explicit reference to Mrs Benson’s discriminatory attitudes in the series. Viewsers can “visit” virtual representations of the program’s sets. In the bedroom, kitchen, living room and/or backyard of each protagonist can be discovered familiar and additional details of the characters’ lives. The artefacts that can be “played” with in the multimedia applications often imply the enthusiastic (and apparently desirable) adoption of “Australianness” by immigrant children. Lily’s toys (her doll, hair accessories, roller skates, and glass marbles) invoke various aspects of western children’s culture, while her “journal entry” about Phuong states that she is “new to Australia but with her sense of humour she has fitted in really well.” At the same time, the interactive elements within Lily’s kitchen, including a bowl of rice and other Asian food ingredients, emphasise cultural continuity. The description of incense in another room of Lily’s house as a “common link” that is “used in many different cultures and religions for similar purposes” clearly normalises a glocalised world-view. Artefacts inside the restaurant operated by Lily’s mother link to information ranging from the ingredients and (flexible) instructions for how to make rice paper rolls (“Lily and Phuong used these fillings but you can use whatever you like!”) to a brief interactive puzzle game requiring the arrangement of several peppers in order from least hot to most hot. A selectable picture frame downloads a text box labelled “Images of Home.” Combined with a slideshow of static, hand-drawn images of traditional Vietnamese life, the text can be read as symbolic of the multiplicity of My Place’s target audience(s): “These images would have reminded the family of their homeland and also given restaurant customers a sense of Vietnamese culture.” The social-developmental, postcolonial agenda of My Place is registered in both “conventional” ancillary texts, such as the series’ “making of” publication (Wheatley), and the elaborate pedagogical website for teachers developed by the ACTF and Educational Services Australia (http://www.myplace.edu.au/). The politicising function of the latter is encoded in the various summaries of each decade’s historical, political, social, cultural, and technological highlights, often associated with the plot of the relevant episode. The page titled “Multiculturalism” reports on the positive amendments to the Commonwealth’s Migration Act 1958 and provides links to photographs of Vietnamese migrants in 1982, exemplifying the values of equality and cultural diversity through Lily and Phuong’s story. The detailed “Teaching Activities” documents available for each episode serve a similar purpose, providing, for example, the suggestion that teachers “ask students to discuss the importance to a new immigrant of retaining links to family, culture and tradition.” The empathetic positioning of Phuong’s situation is further mirrored in the interactive map available for teacher use that enables children to navigate a boat from Vietnam to the Australian coast, encouraging a perspective that is rarely put forward in Australia’s mass media. This is not to suggest that the My Place project is entirely unproblematic. In her postcolonial analysis of Aboriginal children’s literature, Clare Bradford argues that “it’s all too possible for ‘similarities’ to erase difference and the political significances of [a] text” (188). Lily’s schoolteacher’s lesson in the episode “reminds us that boat people have been coming to Australia for a very long time.” However, the implied connection between convicts and asylum seekers triggered by Phuong’s (mis)understanding awkwardly appropriates a mythologised Australian history. Similarly in the “1998” episode, the Muslim character Mohammad’s use of Ramadan for personal strength in order to emulate the iconic Australian cricketer Shane Warne threatens to subsume the “difference” of the diasporic community. Nonetheless, alongside the similarities between individuals and the various ethnic groups that make up the My Place community, important distinctions remain. Each episode begins and/or ends with the child protagonist(s) playing on or around the central motif of the series—a large fig tree—with the characters declaring that the tree is “my place.” While emphasising the importance of individuality in the project’s construction of child citizens, the cumulative effect of these “my place” sentiments, felt over time by characters from different socio-economic, ethnic, and cultural backgrounds, builds a multifaceted conception of Australian identity that consists of numerous (and complementary) “branches.” The project’s multi-platformed content further emphasises this, with the website containing an image of the prominent (literal and figurative) “Community Tree,” through which the viewser can interact with the generations of characters and families from the series (http://www.abc.net.au/abc3/myplace/). The significant role of the ABC’s My Place project showcases the ABC’s remit as a public broadcaster in the digital era. As Tim Brooke-Hunt, the Executive Head of Children’s Content, explains, if the ABC didn’t do it, no other broadcaster was going to come near it. ... I don’t expect My Place to be a humungous commercial or ratings success, but I firmly believe ... that it will be something that will exist for many years and will have a very special place. Conclusion The reversion to iconic aspects of mainstream Anglo-Australian culture is perhaps unsurprising—and certainly telling—when reflecting on the network of local, national, and global forces impacting on the development of a cultural commons. However, this does not detract from the value of the public broadcaster’s construction of child citizens within a clearly self-conscious discourse of “multiculturalism.” The transmedia intertextuality at work across ABC3 projects and platforms serves an important politicising function, offering positive representations of diasporic communities to counter the negative depictions children are exposed to elsewhere, and positioning child viewsers to “participate” in “working through” fraught issues of Australia’s past that still remain starkly relevant today.References ABC. Redefining the Town Square. ABC Annual Report. Sydney: ABC, 2009. Bennett, James, and Niki Strange. “The BBC’s Second-Shift Aesthetics: Interactive Television, Multi-Platform Projects and Public Service Content for a Digital Era.” Media International Australia: Incorporating Culture and Policy 126 (2008): 106-19. Born, Georgina. Uncertain Vision: Birt, Dyke and the Reinvention of the BBC. London: Vintage, 2004. boyd, danah. “Why Youth ♥ Social Network Sites: The Role of Networked Publics in Teenage Social Life.” Youth, Identity, and Digital Media. Ed. David Buckingham. Cambridge: MIT, 2008. 119-42. Bradford, Clare. Reading Race: Aboriginality in Australian Children’s Literature. Carlton: Melbourne UP, 2001. Brooke-Hunt, Tim. Executive Head of Children’s Content, ABC TV. Interviewed by Dr Leonie Rutherford, ABC Ultimo Center, 16 Mar. 2010. Buckingham, David. After the Death of Childhood: Growing Up in the Age of Electronic Media. Cambridge: Polity, 2000. Buckland, Jenny. Chief Executive Officer, Australian Children’s Television Foundation. Interviewed by Dr Leonie Rutherford and Dr Nina Weerakkody, ACTF, 2 June 2010. Caldwell, John T. “Second Shift Media Aesthetics: Programming, Interactivity and User Flows.” New Media: Theories and Practices of Digitextuality. Eds. John T. Caldwell and Anna Everett. London: Routledge, 2003. 127-44. Debrett, Mary. “Riding the Wave: Public Service Television in the Multiplatform Era.” Media, Culture & Society 31.5 (2009): 807-27. From, Unni. “Domestically Produced TV-Drama and Cultural Commons.” Cultural Dilemmas in Public Service Broadcasting. Eds. Gregory Ferrell Lowe and Per Jauert. Göteborg: Nordicom, 2005. 163-77. Glen, David. Executive Producer, ABC Multiplatform. Interviewed by Dr Leonie Rutherford, ABC Elsternwick, 6 July 2010. Harries, Dan. “Watching the Internet.” The New Media Book. Ed. Dan Harries. London: BFI, 2002. 171-82. Murdock, Graham. “Building the Digital Commons: Public Broadcasting in the Age of the Internet.” Cultural Dilemmas in Public Service Broadcasting. Ed. Gregory Ferrell Lowe and Per Jauert. Göteborg: Nordicom, 2005. 213–30. My Place, Volumes 1 & 2: 2008–1888. DVD. ABC, 2009. Northam, Jean A. “Rehearsals in Citizenship: BBC Stop-Motion Animation Programmes for Young Children.” Journal for Cultural Research 9.3 (2005): 245-63. Wheatley, Nadia. Making My Place. Sydney and Auckland: HarperCollins, 2010. ———, and Donna Rawlins. My Place, South Melbourne: Longman, 1988.

 The purpose of this project was to prove or disprove the hypothesis that wheel and rail wear, and incidents of wheel squeal increase with increasing bogie rotation friction, while decreasing bogie rotation friction leads to increased incidents of hunting and increased wheel and rail wear. Therefore for any given combination of factors (vehicle type, curve radius, wheel profile, etc) an optimal bogie rotation friction level should exist at which incidents of hunting and wheel squeal are eliminated and wheel and rail wear is minimised. 

In order to test the hypothesis a literature review was first undertaken. The purpose of the review was to examine the results from previous similar projects and identify any areas that may be improved upon in order to achieve the most accurate results. As a result of the literature review the simulation vehicle model was designed. Past studies featured a three-dimensional wagon body with the centre bowl connection modelled as a single spring, or the centre bowl was modelled in isolation. However for this project the vehicle included a centre bowl connection modelled using centre plate springs evenly distributed across the top centre, and plate and rim friction on the centre bowl, radial bumpstops around the rim and a vertical restraint from the cotter pin. Additional features of the simulation vehicle model were friction wedges, in order to properly represent the damping present at the spring nest connection, and a non -circular top centre, to reflect the design currently used by QR (Queensland Rail). 

The remainder of the project focussed on computer simulations of the vehicle model using different combinations of parameters (vehicle type, curve radius, wheel profile, centre bowl friction and loading condition) to examine the way that the vehicle behaviour responded. The vehicle response was determined by measuring the wheelset lateral position, wheelset angle of attack and wear index (calculated using creep force and creepage). 

The first series of simulations were used to prove that the centre bowl friction levels could be determined using wayside monitoring equipment provided that particular conditions were met. Provided that the vehicle was travelling through an area of constant curvature (not in transition or tangent), in 75% of cases the centre bowl friction level to lateral position relationship was relatively linear. Therefore after initial studies to calibrate the system according to the curve radius and type of vehicle it would be possible to calculate the centre bowl friction using wayside monitoring equipment. However if the system was limited to curves with a radius larger than 800m, the accuracy of the system increased to 83% of cases following a linear relationship.   

It is still a challenge to properly simulate the complex stick-slip behavior of multi-degree-of-freedom systems. In the present paper we investigate the self-excited nonlinear responses of bowed bars, using a time-domain modal approach, coupled with an explicit model for the frictional forces, which is able to emulate stick-slip behavior. This computational approach can provide very detailed simulations and is well suited to deal with systems presenting a dispersive behavior. The effects of the bar supporting fixture are included in the model, as well as a velocity-dependent friction coefficient. We present the results of numerical simulations, for representative ranges of the bowing velocity and normal force. Computations have been performed for constant-section aluminum bars, as well as for real vibraphone bars, which display a central undercutting, intended to help tuning the first modes. Our results show limiting values for the normal force FN and bowing velocity y˙bow, for which the “musical” self-sustained solutions exist. Beyond this “playability space”, double period and even chaotic regimes were found for specific ranges of the input parameters FN and y˙bow. As also displayed by bowed strings, the vibration amplitudes of bowed bars also increase with the bow velocity. However, in contrast to string instruments, bowed bars “slip” during most of the motion cycle. Another important difference is that, in bowed bars, the self-excited motions are dominated by the system first mode. Our numerical results are qualitatively supported by preliminary experimental results.

The Soft Yoke Mooring and Offloading system (SYMO®) has been developed in SBM to allow the tandem mooring of an LNG carrier to the stern of an LNG FPSO or a Floating, Storage & Regasification Unit in harsh environments. The SYMO® system consists of two mooring legs supported by a crane. A yoke structure is suspended at the bottom of the two mooring legs by uni-joints. The tip of the yoke is connected to the bow of the LNG carrier via roll, pitch and yaw articulations. When connected the yoke structure is horizontal. Upon disconnection, the yoke settles at an equilibrium position characterized by a pitch angle of 35° to 40° with respect to the horizontal. Owing to the low friction articulations, the yoke oscillations decay very slowly and the yoke may come too close to the LNG carrier bow. A passive system has been developed to improve the SYMO® dynamics at disconnection whereby a small proportion of the overall yoke weight is replaced by water. This water is allowed to move in a suitably designed tank network thus shifting around the overall centre of gravity and yoke equilibrium angle as pitch oscillations take place. The above principle has first been investigated using a kinematics program before being model tested at a large scale of 1:16. A large matrix of tests has been performed to investigate the effect of the water ballast volume and the layout of the tank network. Once the principle was confirmed experimentally, CFD computations were performed in a blind fashion and compared to the experiments.

Generally, in the accidental limits design domain, the ship/iceberg impacts are divided into external mechanics and internal mechanics. The external mechanics deals with the momentum and energy balance while the internal mechanics is dealing with local structure failure. The present paper focuses on the former one. Due to large contact force, it is reasonable to neglect all other forces here. The ship/iceberg impact might usually happen as an eccentric impact, because the collision is likely to take place in the foreship area. Experience has shown that in such cases, the ship and iceberg motion, like roll, pitch and yaw ect., all should be considered. Based on this, a full 6 DOF closed form theory of the external mechanics of ship/iceberg collision is derived based on Strong (2004) and T.Pedersen and Zhang’s work (1998). And the theory is applied to study the ship/iceberg collision. One challenge here is to obtain the geometrical features of the iceberg, like the COG (center of gravity), mass and also the gyration radius. Due to the large possibilities of the iceberg shape and size, a simplified iceberg geometry shape is proposed to be representative of real shapes. The parametric study here focuses on the geometry shape of the ship hull in the bow area in the form of waterline angle and frame angle. What’s more, the vertical collision position and the friction factor are also investigated. Discussions and conclusions based on the results will be presented.

AbstractWireline logging in a complex well profile, such as extended reach drilling (ERD) wells, presents many challenges for conveyance and data quality. Traditional pipe conveyed logging (PCL) or coiled tubing (CT) are prohibitive in terms of rig time, operational complexity and cost. Alternatively, tractor conveyance is limited by the available force in long laterals. Tools and accessories create higher friction and might jeopardize tool position in the horizontal section. Consequently, both data quality and reaching total depth are compromised. This paper details an innovative deployment technique using oriented wheels to address these challenges.The new centralizing system, comprised of bespoke wheeled carriages, takes a holistic approach to tool conveyance, reducing drag while ensuring optimum sensor orientation. Tool position is achieved through management of tool center of gravity, relative to the wheel axes. The idea of "centralizing by decentralizing" uses the wheeled carriages instead of bow spring centralizers. An eccentered counterweight is included to ensure the proper orientation of the logging sensors.In addition to improving data quality with proper centralization, the wheels minimize friction and the required force to push the toolstring when combined with a tractor. This enables the toolstring to safely and efficiently reach the well bottom and avoid multiple attempts and associated downhole failures. In the planning phase, calibrated software simulation parameters for this technique help to predict free-fall depth and required tractoring force.The wheeled carriages were deployed in an ERD well for cement evaluation across a 9-5/8" casing and could reach a world record of 85° by gravity. The reduced friction and optimized tool position resulted in higher tractor force margins; and so a net gain in the overall tractoring distance. Also, the low drag and surface tension enabled a sufficient pull capacity with a minimum drive combination. For data acquisition, this deployment enabled a minimum eccentricity, resulting in better cement evaluation data quality and reduced uncertainty related to interpretation. In addition to these benefits, a tangible and direct savings of rig time has improved safety, operational efficiency and well delivery KPIs. Oriented wheels with tractors were deployed in other challenging environments and showed consistent and reliable results.This innovative technique can be deployed in both open-hole and cased-hole with fitted design depending on the borehole size, well profile and complexity of the toolstring configuration.