• $1 Internet - exploiting limited bandwidth in developing countries

      Heinz, Ignatz; Dennett, Christopher Paul (2008)
      INFONET-BioVision.org is an freely available internet based knowledge-management system, funded by the Liechtenstein Development Service (LDS) and the BioVision Foundation for Environment and Development, that offers Kenyan farmers information on affordable, effective and ecologically sound technologies in crop and livestock production as well as environmental and human health. One of the challenges faced by the project is the secure provision of information to the rural areas that would most benefit from advice on crop pests and productivity [Avallain, 2008] . Bandwidth is sometimes available in these areas, but is limited, unmanaged and relatively expensive. This paper discusses current work in the development of a novel system that brings together hardware and software to make better use of available bandwidth, whilst offering a financially viable and sustainable method of extending internet provision to these hard-to-reach areas, providing rural farmers with access to the INFONET-BioVision platform and other internet based sources of information. The system currently in development is premised on the fact that some internet based applications require more bandwidth than others. Moreover, their real-time requirements differ greatly. Although it is conceivable that a number of users can share low-bandwidth connections, the multiple bandwidth requests created can easily overwhelm the connection due to the way in which these are managed by protocols developed for bandwidth-rich countries. This results in virtually no bandwidth availability for the user applications themselves. It is clear, therefore, that to maximise the number of users on one low-bandwidth connection, allocation should take place before applications actually make the bandwidth requests. Indeed, similar bandwidth management exists on a larger scale, with domestic broadband providers controlling the amount of data provided through existing channels to a home user at the exchange, based on a tariff system. The system effectively applies a scaled down version of this scenario to available connectivity, be that GPRS, satellite or wired. An inexpensive single-board computer acts as a hub between users and internet, allowing software management of bandwidth and connectivity to users mobile devices through Wi-Fi, Bluetooth and wired LAN. The allocation of bandwidth to each user is based on a voucher system that effectively splits the cost of the connection. Users purchase these vouchers, which are priced according to usage, ranging from very low, none real-time e-mail access to more expensive web-browsing, prior to accessing the system. The proposed system is intended to provide communities with inexpensive connectivity through shared costs which is scaleable, such that, should there be a requirement for extra provision of bandwidth or number of users, subsequent devices can be added or moved simply, easily and at low cost. The system is scheduled for testing later in 2008, at which point a full evaluation will be undertaken.
    • 3D Scene Creation Using Story-Based Descriptions

      Zeng, Xin; Mehdi, Qasim; Gough, Norman (University of Wolverhampton, School of Computing and Information Technology, 2005)
      Developments in the creation of 3D virtual environments have made this a popular approach in a variety of applications. However, creating 3D scenes still requires professionals to spend an enormous amount of effort and time on it. In this paper, we present a fully implemented prototype system called 3DSV (3D Story Visualiser) that generates a virtual scene by using simplified story-based descriptions. This prototype system is based on the integration of advances in computer graphics and text-tovisualization technology to generate 3D virtual environment. This makes it easier and faster for nonprofessionals to create 3D environments compared to using traditional 3D design packages.
    • A 140-year-old specimen from the southern Trans-Fly region of Papua New Guinea proves that the Eastern Brownsnake, Pseudonaja textilis, was not a wartime or post-war introduction (Serpentes, Elapidae, Hydrophiinae)

      O'Shea, Mark; Doria, Giuliano; Petri, Massimo; Kaiser, Hinrich (Museo Civico di Storia Naturelle, Genova, 2016-10-20)
      Abstract: The medically important Australian elapid Pseudonaja textilis was first documented for the island of New Guinea in the 1950s, when specimens from the northern coast of the Papuan Peninsula were collected and identified. It was initially believed that these snakes were from an invasive population that established post-World War II, a concept generally accepted over following decades. More recently molecular evidence and additional specimens, from West New Guinea and the southern coast of the Papuan Peninsula, have suggested that the New Guinea populations are indigenous. However, no pre-World War II specimens have been found to dismiss the human-mediated introduction argument. We here present the earliest known Papuan voucher specimen of P. textilis, a juvenile from collections housed in Genoa made by Luigi Maria D’Albertis in 1876 that pre-dates all other vouchers and the New Guinea Campaign (1942-1945) of World War II by 77 and 66 years, respectively. We also discuss the origins of P. textilis in New Guinea, the history of its discovery, and the Pleistocene routes of its invasion from Australia.
    • A 300-year record of sedimentation in a small tilled catena in Hungary based on δ13C, δ15N, and C/N distribution

      Jakab, Gergely; Hegyi, István; Fullen, Michael A.; Szabó, Judit; Zacháry, Dóra; Szalai, Zoltán (Springer, 2018-01-04)
      Purpose Soil erosion is one of the most serious hazards that endanger sustainable food production. Moreover, it has marked effects on soil organic carbon (SOC) with direct links to global warming. At the same time, soil organic matter (SOM) changes in composition and space could influence these processes. The aim of this study was to predict soil erosion and sedimentation volume and dynamics on a typical hilly cropland area of Hungary due to forest clearance in the early eighteenth century. Materials and methods Horizontal soil samples were taken along two parallel intensively cultivated complex convex-concave slopes from the eroded upper parts at mid-slope positions and from sedimentation in toe-slopes. Samples were measured for SOC, total nitrogen (TN) content, and SOMcompounds (δ13C, δ15N, and photometric indexes). They were compared to the horizons of an in situ non-eroded profile under continuous forest. On the depositional profile cores, soil depth prior to sedimentation was calculated by the determination of sediment thickness. Results and discussion Peaks of SOC in the sedimentation profiles indicated thicker initial profiles, while peaks in C/N ratio and δ13C distribution showed the original surface to be ~ 20 cm lower. Peaks of SOC were presumed to be the results of deposition of SOC-enriched soil from the upper slope transported by selective erosion of finer particles (silts and clays). Therefore, changes in δ13C values due to tillage and delivery would fingerprint the original surface much better under the sedimentation scenario than SOC content. Distribution of δ13C also suggests that the main sedimentation phase occurred immediately after forest clearance and before the start of intense cultivation with maize. Conclusions This highlights the role of relief in sheet erosion intensity compared to intensive cultivation. Patterns of δ13C indicate the original soil surface, even in profiles deposited as sediment centuries ago. The δ13C and C/N decrease in buried in situ profiles had the same tendency as recent forest soil, indicating constant SOM quality distribution after burial. Accordingly, microbiological activity, root uptake, and metabolism have not been effective enough to modify initial soil properties.
    • A Case for Target Value Design towards Effective Low-Cost Housing Project Cost Management and Performance South-East Zone Nigeria

      Obi, Lovelin Ifeoma; Arif, Mohammed (IBEA Publications Ltd London, 2015)
      Reports over the past decade, reveal the trend of poor cost performances of many Low-cost Housing (LcH) projects. This have apparently resulted in huge monetary losses to the government as the client, declining housing supply and undermined affordability of many Low and Low-medium incomes particularly in developing countries like Nigeria. In spite of the changes with contemporary trends in Nigeria, it would appear that the techniques employed in the management of the delivery costs of the LcH projects particularly in the South-east zone are yet similar to those used over a century ago. This necessitates urgent and appropriate sustainable intervention strategies adopting cost-effective techniques. Prior studies affirms the implications of modern cost management techniques such as Target Value Design (TVD) in improving delivery cost performances on construction projects. For this reason this paper which forms an integral part of an ongoing doctoral study, aim to identify the efficacy and applicability of TVD in the context of LcH project delivery cost management. A review of relevant and extant literature identifies peculiarities on the concept of TVD and LcH projects. Findings from literature and data collected via questionnaires further identify constraints on current LcH project delivery cost management system and clearly indicates the possible applicability and integration of TVD in the system. These findings provide a platform for the next phase of the research towards developing an improved delivery cost management model for LcH projects. This is expected to engender effective government-led LcH projects delivery particularly in in South-East zone Nigeria.
    • A CASE STUDY OF JOINT PROCUREMENT AND PROVISION OF LEGAL SERVICES TO A GROUP OF A UNIVERSITIES IN THE MIDLANDS

      Charlson, Jennifer; Chinyio, Ezekiel A. (ARCOM, 2013-09-02)
      A Group of 5 UK Universities in the Midlands undertook a joint procurement process for the provision of Legal Services. The objective was to put in place common Framework Agreements. The Legal Services procured were divided into six lots and one of these was 'Property and Construction'. The lots were assembled into three packages and the contract for each package was awarded to one or more Service Providers. Albeit a service provider is to work for all the collaborating Universities. A competitive 'restricted' two-stage tender process was administered in accordance with the Public Contracts Regulations 2006, SI 2006/5. The Framework Agreements were awarded in 2012 to the most economically advantageous Solicitors' Practices. The participating Universities are being interviewed about the reasons for the joint procurement exercise, any challenges faced in its implementation and lessons learnt so far. Two interviews have been conducted so far and evaluated via content analysis to reveal that advantages to be gained from 'economy of scale' were the main impetus for the collaborative procurement. The negotiations between the Universities which led to the establishment of the collaboration and its subsequent sustenance have been friendly. The challenge identified so far concerns how to distribute work more fairly to legal services providers.
    • A Case Study on the Microstructure of Fibrous Peat (West Lake, China)

      Wilkinson, Stephen; Zhao, Chaofa; Yang, Zhongxuam; Kun, Pan (Springer, 2018-09-21)
      The classification of peat soils generates a very large number of different types, from a descriptive perspective this is useful, however such a system generates too many options for engineering purposes. The behaviour of organic soils varies based on the quantity and type of organic material present within the soil. The effects of fibre content are particularly important. The West Lake in Hangzhou has been dredged many times during its history to allow it to maintain its beauty. During the most recent dredging the sludge from the lake was transported via a 4km pipeline and deposited inside the Jiangyangfan Reservoir. The organic soil situated in Jiangyangfan Ecopark is a particularly interesting peaty material. The organic sludge was mixed and homogenised during the transportation process, and then would have settled out within the reservoir. This resulted in a more than 20m thick peat layer deposited with an uneven surface. The Ecopark buildings were then constructed on top of this in 2008. A combined electron microscope and mechanical study of the microstructure and behaviour of the peat has been used to identify the engineering impact of the presence of relatively small numbers of fibres within the soil matrix. The fibres within the peat modify its behaviour such that it can no longer be understood within the typical critical state framework for soils. The peat starts to plastically deform from very small levels of applied stress, in addition it does not display a tension cut-off failure, and ultimately fails in shear.
    • A Closed-Loop Reciprocity Calibration Method for Massive MIMO in Terrestrial Broadcasting Systems

      Luo, Hua; Zhang, Yue; Huang, Li-Ke; Cosmas, John; Aggoun, Amar (IEEE, 2016-09-22)
      Massive multi-input multioutput (MIMO) is believed to be an effective technique for future terrestrial broadcasting systems. Reciprocity calibration is one of the major practical challenges for massive MIMO systems operating in time-division duplexing mode. A new closed-loop reciprocity calibration method is investigated in this paper which can support online calibration with a higher accuracy compared to the existing methods. In the first part of the proposed method, an optimized relative calibration is introduced using the same structure of traditional relative calibration, but with less impaired hardware in the reference radio chain. In the second part, a test device (TD)-based calibration is proposed which makes online calibration possible. An experiment setup is built for the measurement of the base station hardware impairments and TD-based calibration implementation. Simulation results and the error vector magnitude of UE received signal after calibration show that the performance of our proposed method is improved significantly compared to the existing relative calibration methods.
    • A comparative study of analytical methodologies to determine the soil organic matter content of Lithuanian Eutric Albeluvisols

      Jankauskas, Benediktas; Slepetiene, Alvyra; Jankauskiene, Genovaite; Fullen, Michael A.; Booth, Colin A. (2006)
      Large archive databases of soil organic matter (SOM) widely exist in Lithuania and the other countries of Central and Eastern Europe. Despite the demise of the former Soviet Union over 16 years ago, and Lithuania's integration as a full European Union state, difficulties of SOM data acceptance remain where these results are presented for publication in international journals, due to methodological differences between laboratory protocols. Therefore, the scientific pilot project ‘Carbon sequestration in Lithuanian soils’, supported by the Leverhulme Trust (U.K.), included an objective to correlate soil carbon methodologies, using Lithuanian Eutric Albeluvisols. A comparison of SOM content data acquired using five different analytical methods is reported. The research programme included a specific objective to correlate analytical methods for SOM analyses. A total of 92 Eutric Albeluvisol samples were collected from topsoil (0–0.2 m: Ap, n=36; Ah, n=10) and subsoil (0.2–0.4 m: Bt, n=46) horizons of 46 long-term experimental field plots at the Kaltinenai Research Station of the Lithuanian Institute of Agriculture. Each sample was then subsampled and analysed for SOM using dry combustion (by automatic elemental analyser), Walkley–Black (USDA), Tyurin photometrical, Tyurin titrimetrical and loss-on-ignition (LoI) methods (the later performed, in parallel, in both Lithuania and U.K. laboratories). Linear correlation and paired regression equations were calculated. Correlation coefficients between the sets of results varied between r=0.81–0.96 (from 0–0.2 m, n=46, P<0.001) and r=0.76–0.98 (from 0.2–0.4 m, n=46, P<0.001). Based on the strength and significance of these relationships, it is proposed that simple linear or more complex paired regression equations can be confidently employed to recalculate SOM data between various analytical methodologies. Future work will continue these investigations on other soil units and environments, hereby enhancing the database.
    • A comparative study of three-dimensional printing directions: The degradation and toxicological profile of a PLA/PHA blend

      Gonzalez Ausejo, Jennifer; Rydz, Joanna; Musioł, Marta; Sikorska, Wanda; Sobota, Michał; Włodarczyk, Jakub; Adamus, Grażyna; Janeczek, Henryk; Kwiecień, Iwona; Hercog, Anna; Johnston, Brian; Khan, Habib R.; Kannappan, Vinodh; Jones, Keith R.; Morris, Mark R.; Jiang, Gouzhan; Radecka, Iza; Kowalczuk, Marek (Elsevier, 2018-06)
      The use of biobased plastics is of great importance for many applications. Blending thermoplastic polylactide (PLA) with polyhydroxyalkanoate (PHA) enables the formulation of a more mechanically powerful material and this enables tailored biodegradation properties. In this study we demonstrate the 3D printing of a PLA/PHA blend as a potential candidate for biocompatible material applications. The filament for 3D printing consisted of PHA, which contains predominantly 3-hydroxybutyrate units and a small amount of 3-hydroxyvalerate units, as revealed by multistage mass spectrometry (ESI-MSn). This research found that the properties of 3D printed species before and during abiotic degradation are dependent on printing orientation. Furthermore, the 3D printed specimens exhibited good biocompatibility with HEK293 cells, indicating real promise as biological scaffolds for tissue engineering applications.
    • A comparison of sources of links for academic Web impact factor calculations

      Thelwall, Mike (MCB UP Ltd, 2002)
      There has been much recent interest in extracting information from collections of Web links. One tool that has been used is Ingwersen¿s Web impact factor. It has been demonstrated that several versions of this metric can produce results that correlate with research ratings of British universities showing that, despite being a measure of a purely Internet phenomenon, the results are susceptible to a wider interpretation. This paper addresses the question of which is the best possible domain to count backlinks from, if research is the focus of interest. WIFs for British universities calculated from several different source domains are compared, primarily the .edu, .ac.uk and .uk domains, and the entire Web. The results show that all four areas produce WIFs that correlate strongly with research ratings, but that none produce incontestably superior figures. It was also found that the WIF was less able to differentiate in more homogeneous subsets of universities, although positive results are still possible.
    • A Computationally-Efficient Numerical Model to Characterize the Noise Behavior of Metal-Framed Walls

      Arjunan, Arun; Wang, Chang; English, Martin; Stanford, Mark; Lister, Paul (MDPI AG, Basel, Switzerland, 2015-08-07)
      Architects, designers, and engineers are making great efforts to design acoustically-efficient metal-framed walls, minimizing acoustic bridging. Therefore, efficient simulation models to predict the acoustic insulation complying with ISO 10140 are needed at a design stage. In order to achieve this, a numerical model consisting of two fluid-filled reverberation chambers, partitioned using a metal-framed wall, is to be simulated at one-third-octaves. This produces a large simulation model consisting of several millions of nodes and elements. Therefore, efficient meshing procedures are necessary to obtain better solution times and to effectively utilise computational resources. Such models should also demonstrate effective Fluid-Structure Interaction (FSI) along with acoustic-fluid coupling to simulate a realistic scenario. In this contribution, the development of a finite element frequency-dependent mesh model that can characterize the sound insulation of metal-framed walls is presented. Preliminary results on the application of the proposed model to study the geometric contribution of stud frames on the overall acoustic performance of metal-framed walls are also presented. It is considered that the presented numerical model can be used to effectively visualize the noise behaviour of advanced materials and multi-material structures.
    • A computer-aided environment for construction of multiple-choice tests

      Mitkov, Ruslan; Ha, Le An; Bernardes, Jon (University of Wolverhampton, 2005)
      Multiple choice tests have proved to be an efficient tool for measuring students' achievement and are used on a daily basis both for assessment and diagnostics worldwide. The objective of this project was to provide and alternative to the lengthy and demanding activity of developing multiple-choice tests and propose a new Natural Language Processing (NLP) based approach to generate tests from instructional texts (textbooks, encyclopaedias). Work on the pilot project has shown that the semi-automatic procedure is up to 3.8 times quicker than a completely manual one.
    • A critical review of factors affecting manpower and equipment productivity in tall building construction projects

      Parthasarathy, Mudumbai Krishnaswamy; Murugasan, Rajiah; Murugesan, Kavitha (2017-12-05)
      Developing countries have seen an increase in construction of tall buildings in metropolitan cities due to space constraint. The construction of tall buildings in developing countries is undertaken as a combination of manpower and equipment to economize costs. This combination or interface of manpower and equipment, particularly in the basic activities such as concreting, reinforcement, formwork, blockwork, and plastering affects productivity of both the resources. This research aims at studying the factors affecting productivity of manpower and equipment at the micro level for the basic activities of construction for tall building projects. The factors have been further grouped and combined as sections. Responses collected through questionnaire survey from 109 personnel associated with the construction of 72 tall buildings in different geographies of India have been analysed using theoretical tools like frequency index, Spearman's rank correlation coefficient, and factor analysis. The factors have been prioritized in descending order of frequency indices. Based on analysis, it is found that factors in human and planning groups are more influential and affect manpower and equipment productivity significantly. Contract managers and cost engineers can use this study to make allowance while analysing productivity and estimating costs for tall buildings having combined usage of manpower and equipment.
    • A critical review of the effective use of expert witnesses in construction disputes

      Charlson, Jennifer; Smalley, James (Sweet & Maxwell, 2014)
      Discusses the role and duties of expert witnesses in construction law disputes, and considers the issues of concern that have been raised about the quality of their evidence. Presents the findings of research exploring the views of legal and construction industry professionals on: (1) the level of control that clients have over expert witnesses; (2) experts' standards of objectivity; (3) their qualifications and training; (4) the future use of tribunal experts; (5) the impact of the Supreme Court judgment in Jones v Kaney removing experts' immunity; and (6) the cost of engaging experts.
    • A Decision Support Tool for the Valuation of Variations on Civil Engineering Projects

      Sutrisna, Monty; Buckley, Kevan; Potts, Keith F.; Proverbs, David G. (RICS (Royal Institute of Chartered Surveyors), 2005)
      The valuation of variations has been recognised as a prime cause of conflict and dispute in construction management. Such disputes often concern the prices and/or rates to be applied to the varied works. Previous research has identified the subjectivity of the decision-maker in interpreting the valuation rules to be the major problem, particularly with regard to defining the work conditions and/or characteristics during a variation event. Findings of a survey, conducted to elicit the views and perceptions of experienced practitioners towards interpreting the valuation rules are presented. The development of a decision-making tool based on a robust framework for valuing variations in civil engineering projects is described. The tool was developed by analysing changes in various decision attributes. The result of the changes was then mapped to relevant sets developed using fuzzy-logic principles. Various operators were used to perform the fuzzy-aggregation operation. The modelling technique was demonstrated to be reliable in replicating the decision-making process performed by experienced practitioners. As such is considered a suitable aid for decision-making involved in valuing variations on civil engineering works. The results of the analysis reported here have suggested the fuzzy-logic as an appropriate tool to model human decision-making, particularly in valuing variations on civil engineering works. This is considered an essential progress of the current study in modelling human decision-making process, particularly since there are so many unknown aspects associated with such a process. The modelling technique successfully developed here is then used as the main algorithm for decision-making in the subsequently developed Knowledge Based System (KBS) which is intended to assist practitioners minimise conflict and dispute arising from the valuation of variations.
    • A disease-linked ULBP6 polymorphism inhibits NKG2D-mediated target cell killing by enhancing the stability of NKG2D-ligand binding

      Zuo, Jianmin; Willcox, Carrie R; Mohammed, Fiyaz; Davey, Martin; Hunter, Stuart; Khan, Kabir; Antoun, Ayman; Katakia, Poonam; Croudace, Joanne; Inman, Charlotte; Parry, Helen; Briggs, David; Malladi, Ram; Willcox, Benjamin E; Moss, Paul (American Association for the Advancement of Science, 2017-05)
      NKG2D (natural killer group 2, member D) is an activating receptor found on the surface of immune cells, including natural killer (NK) cells, which regulates innate and adaptive immunity through recognition of the stress-induced ligands ULBP1 (UL16 binding protein 1) to ULBP6 and MICA/B. Similar to class I human leukocyte antigen (HLA), these NKG2D ligands have a major histocompatibility complex–like fold and exhibit pronounced polymorphism, which influences human disease susceptibility. However, whereas class I HLA polymorphisms occur predominantly in the α1α2 groove and affect antigen binding, the effects of most NKG2D ligand polymorphisms are unclear. We studied the molecular and functional consequences of the two major alleles of ULBP6, the most polymorphic ULBP gene, which are associated with autoimmunity and relapse after stem cell transplantation. Surface plasmon resonance and crystallography studies revealed that the arginine-to-leucine polymorphism within ULBP0602 affected the NKG2D-ULBP6 interaction by generating an energetic hotspot. This resulted in an NKG2D-ULBP0602 affinity of 15.5 nM, which is 10- to 1000-fold greater than the affinities of other ULBP-NKG2D interactions and limited NKG2D-mediated activation. In addition, soluble ULBP0602 exhibited high-affinity competitive binding for NKG2D and partially suppressed NKG2D-mediated activation of NK cells by other NKG2D ligands. These effects resulted in a decrease in a range of NKG2D-mediated effector functions. Our results reveal that ULBP polymorphisms affect the strength of human lymphocyte responses to cellular stress signals and may offer opportunities for therapeutic intervention.
    • A dynamic approach to urban road deposited sediment pollution monitoring (Marylebone Road, London, UK)

      Crosby, C.J.; Fullen, Michael A.; Booth, C.A.; Searle, D.E. (Elsevier, 2014-06)
      The use of mineral magnetic measurements (χLF, χARM and SIRM) as a potential pollution proxy using road deposited sediment (RDS) is explored as an alternative means of monitoring pollution on a busy city road. Comparison of sediment-related analytical data by correlation analysis between mineral magnetic, particle size and geochemical properties is reported. Mineral magnetic concentration parameters (χLF, χARM and SIRM) reveal significant (p < 0.001; n = 61) associations with PM1.0, PM2.5 and PM10. Significant associations were also found with mineral magnetic concentrations (χLF and SIRM) and specific concentrations of the elements Fe, Ni, Cu, Zn and Mn (p < 0.001; n = 61). Inter-geochemical correlation analysis found strong associations (p < 0.001; n = 61) between Fe, Ni, Cu, Zn and Mn and suggest anthropogenic enrichment influences. Low χFD% measurements imply an influence of multi-domain mineralogy, indicative of anthropogenic combustion processes. SEM micrographs also support this, as all samples contain Fe spherules indicative of vehicular combustion processes. This study advocates rapid and simple initial assessment of urban pollution episodes using mineral magnetic measurements as a dynamic explorative technology.
    • A Fast New Numerical Tool for Designing Pre-stressed Dies for Backward Extrusion: Part 1: Die Behaviour

      Bonnavand, F.; Bramley, Alan N.; Mynors, Diane J. (Professional Engineering Publishing, 2001)
      Prestressed die inserts are often used in the forging of axisymmetric parts. Their use enhances overall tool economy and can enhance the quality of the finished forging. The design of tooling that incorporates prestressed die inserts is, however, complex. The complexity arises from the interrelated phenomena that occur within the dies during the forging process. As a result, it is not possible to obtain an analytical expression for critical parameters such as die stresses and deflections. This paper shows the limitations of currently used design methods, and identifies, for the backward extrusion process, which physical phenomena should be taken into account when designing prestressed tooling. (Professional Engineering Publishing)
    • A fast new numerical tool for designing prestressed dies for backward extrusion: Part 2: numerical analysis

      Bonnavand, F.; Bramley, Alan N.; Mynors, Diane J. (Professional Engineering Publishing, 2001)
      The economics of forging requires tools to be designed to ensure maximum service life. Ideally, this should be achieved by determining the maximum equivalent stress experienced by tools during service. However, the determination of the maximum equivalent stress in the dies through numerical simulations is very time consuming. For the case of a backward extrusion process, this paper proposes a method for its determination that is based on an analytical function of the process parameters. This function was obtained by generating a database that includes the maximum equivalent stress for a large range of process parameters. This database was then modelled by a function determined through statistical analysis. (Professional Engineering Publishing)