Now showing items 1-20 of 8177

    • Conceptualizing of value offerings from a customer perspective. Understanding the elements of value and their relationship with customer satisfaction

      Wright, Gillian H.; Mehraramolan, Amirreza (University of BradfordSchool of Management, 2016)
      The initial idea for this research is based on the gap that I found in my company performance and specifically in the process of value offering and the relationship with customers. The company has recently faced the challenges of a loss of market share and competitive advantage. The aim of this study is to provide a validated value offering constructs for the company. That is, knowing the customers’ needs, value and preferences better; identifying what kind of value the customers are looking for and improving the value offerings of the company in order to raise customers´ satisfaction. Understanding the priority of value offering elements from customers’ perspective, the nature of customer satisfaction and the relationship between the elements of value offering and customers´ satisfaction are the main objectives. The relevant literature and research related to value offering including its elements, value, perceived value and customer satisfaction are reviewed comprehensively. The methodology used is a case study. Both quantitative and qualitative methods are used for collecting and analysing the data. In qualitative phase, 16 customers were selected for in-depth interviews and for quantitative phase 268 customers who all are dentists responded a survey made up of 24 scales. The result showed that the highest significant element is Price value and also it was revealed in which important parts related to value offering and customer satisfaction the company is performing poorly.
    • The characteristics of effective leadership in an academic context: A case study of four colleges of technology in Oman

      Spicer, David P.; Maybury, Alan; Al Kalbani, Darwish A.A. (University of BradfordFaculty of Management and Law, 2017)
      Purpose – The purpose of this study is to advance the literature on leadership by investigating the Full Range Leadership Model (FRLM) Bass and Avolio (1994-1997) in the context of the Colleges of Technology (CoTs) in Oman. Design/methodology/approach – In order to achieve the research objective and answer the research questions, a qualitative study was undertaken. The data was obtained by two methods, namely semi-structured interviews and focus groups. The semi-structured interviews were held with College Deans, Heads of Departments (HoDs) and teachers. The focus groups were carried out with seven groups of students from four CoTs. The data was analysed by a thematic approach, following the systematic steps outlined by Braun and Clarke (2006). Findings – Significant relationships were found between the transactional leadership approach and institutional theory (Isomorphism and legitimacy). The findings advance leadership knowledge by exploring the relationship between the components of FRLM, transformational and the transactional leadership approaches in hierarchical levels of leadership in the context of the CoTs in Oman. Both the Deans and the HoDs employed transactional leadership approaches to ensure compliance with the requirements of the Ministry of Manpower. Moreover, the study extended the leadership literature by exploring the interaction between leadership approaches of the Deans and the HoDs on multi-national teachers and Omani students. Originality/value – The originality of this research lies in its exploration of the relationship between transformational and transactional leadership approaches in hierarchical levels of academic leadership and its identification of the characteristics of effective leadership in HEIs from a multicultural perspective.
    • The public health end-of-life care movement: History, principles, and styles of practice

      Karapliagou, Aliki; Kellehear, Allan; Wegleitner, K. (Oxford University Press, 2018)
    • Precision pharmacology: Mass spectrometry imaging and pharmacokinetic drug resistance

      Jove, M.; Spencer, Jade A.; Clench, M.; Loadman, Paul M.; Twelves, C. (2019-09)
      Failure of systemic cancer treatment can be, at least in part, due to the drug not being delivered to the tumour at sufficiently high concentration and/or sufficiently homogeneous distribution; this is termed as “pharmacokinetic drug resistance”. To understand whether a drug is being adequately delivered to the tumour, “precision pharmacology” techniques are needed. Mass spectrometry imaging (MSI) is a relatively new and complex technique that allows imaging of drug distribution within tissues. In this review we address the applicability of MSI to the study of cancer drug distribution from the bench to the bedside. We address: (i) the role of MSI in pre-clinical studies to characterize anti-cancer drug distribution within the body and the tumour, (ii) the application of MSI in pre-clinical studies to define optimal drug dose or schedule, combinations or new drug delivery systems, and finally (iii) the emerging role of MSI in clinical research.
    • DISH Everywhere: Study of the Pathogenesis of Diffuse Idiopathic Skeletal Hyperostosis and of its Prevalence in England and Catalonia from the Roman to the Post-Medieval Time Period

      Buckberry, Jo; Beaumont, Julia; Castells Navarro, Laura (University of BradfordFaculty of Life Sciences, 2018)
      Diffuse idiopathic skeletal hyperostosis (DISH) is a spondyloarthropathy traditionally defined as having spinal and extra-spinal manifestations. However its diagnostic criteria only allow the identification of advanced DISH and there is little consensus regarding the extra-spinal enthesopathies. In this project, individuals with DISH from the WM Bass Donated Skeletal Collection were analysed to investigate the pathogenesis of DISH and archaeological English and Catalan samples (3rd–18th century AD) were studied to investigate how diet might have influenced the development of DISH. From the individuals from the Bass Collection, isolated vertical lesions representing the early stages of DISH (‘early DISH’) were identified. Both sample sets showed that the presence of extra-spinal manifestations varies significantly between individuals and that discarthrosis and DISH can co-exist in the same individual. In all archaeological samples, the prevalence of DISH was significantly higher in males and older individuals showed a higher prevalence of DISH. In both regions, the prevalence of DISH was the lowest in the Roman samples, the highest in the early medieval ones and intermediate in the late medieval samples. While when using documentary resources and archaeological data, it was hypothesised that the prevalence of DISH in the English and Catalan samples might have been different, the results show no significant differences even if English samples tend to show higher prevalence of DISH than the Catalan samples. This possibly suggests that the development of DISH depends on a combination of dietary habits and, possibly, genetic predisposition might influence the development of DISH. The individuals from the Bass Collection showed high prevalence of metabolic and cardiovascular conditions. In contrast, no association was found between DISH and rich-diet associated conditions (e.g. carious lesions and gout) or deficiency-related conditions (e.g. scurvy, healed rickets).
    • Alcohol, empathy, and morality: acute effects of alcohol consumption on affective empathy and moral decision-making

      Francis, Kathryn B.; Gummerum, M.; Ganis, G.; Howard, I.S.; Terbeck, S. (Springer, 2019)
      Rationale: Hypothetical moral dilemmas, pitting characteristically utilitarian and non-utilitarian outcomes against each other, have played a central role in investigations of moral decision-making. Preferences for utilitarian over non-utilitarian responses have been explained by two contrasting hypotheses; one implicating increased deliberative reasoning, and the other implicating diminished harm aversion. In recent field experiments, these hypotheses have been investigated using alcohol intoxication to impair both social and cognitive functioning. These studies have found increased utilitarian responding, arguably as a result of alcohol impairing affective empathy. Objectives: The present research expands existing investigations by examining the acute effects of alcohol on affective empathy and subsequent moral judgments in traditional vignettes and moral actions in virtual reality, as well as physiological responses in moral dilemmas. Methods: Participants (N = 48) were administered either a placebo or alcohol in one of two dosages; low or moderate. Both pre- and post intervention, participants completed a moral action and moral judgment task alongside behavioural measures of affective empathy. Results: Higher dosages of alcohol consumption resulted in inappropriate empathic responses to facial displays of emotion, mirroring responses of individuals high in trait psychopathy, but empathy for pain was unaffected. Whilst affective empathy was influenced by alcohol consumption in a facial responding task, both moral judgments and moral actions were unaffected. Conclusions: These results suggest that facets, beyond or in addition to deficits in affective empathy, might influence the relationship between alcohol consumption and utilitarian endorsements.
    • Similarity hash based scoring of portable executable files for efficient malware detection in IoT

      Namanya, Anitta P.; Awan, Irfan U.; Disso, J.P.; Younas, M. (Elsevier, 2019)
      The current rise in malicious attacks shows that existing security systems are bypassed by malicious files. Similarity hashing has been adopted for sample triaging in malware analysis and detection. File similarity is used to cluster malware into families such that their common signature can be designed. This paper explores four hash types currently used in malware analysis for portable executable (PE) files. Although each hashing technique produces interesting results, when applied independently, they have high false detection rates. This paper investigates into a central issue of how different hashing techniques can be combined to provide a quantitative malware score and to achieve better detection rates. We design and develop a novel approach for malware scoring based on the hashes results. The proposed approach is evaluated through a number of experiments. Evaluation clearly demonstrates a significant improvement (> 90%) in true detection rates of malware.
    • Video rasterstereography of the spine and pelvis in eight erect positions: A reliability study

      Alzyoud, K.; Hogg, P.; Snaith, Beverly; Preece, S.; England, A. (2019)
      Introduction: To investigate the reliability and variability of Video Rasterstereography (VR) measurements of the spine and pelvis, for eight proposed standing postures, in order to help define an optimal standing position for erect pelvis radiography. Methods: Surface topography data were collected using the formetic 4D dynamic modelling (Diers) system. 61 healthy participants were recruited; each participant performed eight different standing positions. Four positions were performed with the feet shoulder width apart and parallel, and four positions were performed with the feet shoulder width apart and internally rotated. For the upper extremity, each of the (two sets of) four positions were performed with different arm positions (arms by the sides, arms crossed over the chest, arms 30° flexed and touching the medial end of the clavicle, arms 30° flexed with the hands holding a support). Three sets of surface topography were collected in the eight positions (n = 24). The variability was assessed by calculating standard error of the measurement (SEm) and the coefficient of variation (CV). Reliability was assessed using intra-class correlation coefficients (ICC ± 95% CI). Results: No significant differences in the SEm were found between the three paired measurements for all standing positions (P > 0.05). ICC values demonstrated excellent reliability for all measurements across the eight standing positions (range 0.879–1.00 [95% CI 0.813–1.00]). Conclusion: Evaluating eight standing positions radiographically would be unethical as it would involve repeat radiation exposures. Using the formetic 4D dynamic modelling (Diers) system, provides an alternative and has shown that there was only a minimal, non-statistically significant, differences between the eight different standing positions.
    • Variation in pelvic radiography practice: Why can we not standardise image acquisition techniques?

      Snaith, Beverly; Field, L.; Lewis, E.F.; Flintham, K. (2019)
      Introduction: Pelvic radiographs remain an essential investigation in orthopaedic practice. Although it is recognised that acquisition techniques can affect image appearances and measurement accuracy, it remains unclear what variation in practice exists and what impact this could have on decision making. Method: This was a cross sectional survey of UK radiology departments utilising an electronic tool. An introductory letter and link was distributed. Responses were received from 69 unique hospital sites within the specified timeframe, a response rate of 37.9%. Results: There was no consistent technique for the positioning of patients for pelvic radiographs. The distance varied between 90 and 115 cm and 10 different centering points were described. In relation to leg position, the feet are usually internally rotated (65 of 69 [94.2%]). Only 1 teaching hospital (1 of 69 [1.4%]) uses a weight-bearing position as standard. Orthopaedic calibration devices were not in routine use, with only 21 using on pelvic x-rays (30.4%). Further, the type of device and application criteria were inconsistent. Conclusions: To our knowledge this is the first study to directly compare radiographic positioning across hospital sites. Our data demonstrated marked variation in technique for pelvis radiographs with associated implications for clinical decision making. Research is required to determine the standard technique and quality outcome measures to provide confidence in diagnostic interpretation particularly for serial radiographs.
    • Expanding training capacity for radiographer reporting using simulation: Evaluation of a pilot academy project

      Harcus, J.W.; Snaith, Beverly (2019)
      Introduction: Whilst there is increasing demand on radiology services in the UK, pressures are restricting the expansion of the multi-professional workforce. A pilot academy for radiography reporting was established to augment the traditional university and clinical education in a simulated environment using focussed teaching and real image worklists in a dedicated environment away from departments. Methods: Located at a facility to replicate the clinical reporting environment, the emphasis of the nine-month pilot was to provide extensive ‘hands-on’ training to eight trainees. Evaluation of the academy was undertaken through focus groups, telephone interviews, and online surveys to consider the experiences of the trainees and their managers and mentors. Results: There was overwhelming support for the academy from trainees, mentors, and managers. Key benefits included relieving pressures on department and mentors; providing an intense, structured, and safe environment to learn; and, perhaps most importantly, an extensive and cohesive peer-support network. Issues identified included conflict within departments due to differences in reporting style and the need for greater collaboration between the university, academy, and departments. Conclusion: The use of simulation in education is widely researched, however, there are a number of key factors that need to be considered when implementing it into practise. Peer-support and reflection is seen as essential for its success. Extensive dedicated time to focus on reporting alongside peers can support the development of these skills away from the clinical environment and as such can reduce pressure on service delivery and positively influence learner outcomes.
    • Investigation of drug ionic liquid salts for topical delivery systems

      Paradkar, Anant R.; Brown, Elaine C.; Karodia, Nazira; Bansiwal, Mukesh (University of BradfordFaculty of Life Sciences, 2017)
      Pharmaceutical companies and FDA (Federal Drug Administration) rules rely heavily on crystalline active pharmaceutical ingredients delivered as tablets and powders in the form of neutral compounds, salts and solvates of neutral compounds and salts. About half of all drugs sold in the market are in the form of salts which are held together by ionic bonds along with some other forces. Recently, Ionic liquids (ILs) an interesting class of chemical compounds have offered potential opportunity for exploration as novel drug ionic liquid salts, particularly in the field of transdermal/topical drug delivery. Due to the multifunctional nature of these salts they could allow generation of new pathway to manipulate the transport and deposition behaviour of the drug molecule. It is this modular approach of IL that forms the basis of the research presented here, in which pharmaceutically acceptable compounds are combined with selected drugs with known problems. IL salts were generated by combining at least one drug molecule with FDA approved compounds and were assessed for physicochemical properties, skin deposition and permeation studies. Skin deposition data suggested that these systems exhibit high skin retention, which was found to correlate with the molecular weight. On the other hand, permeation data displayed an inverse relationship between flux values and molecular weight of the permeant. Similar work was extended with ILs with mixed anions containing two drugs. The benzalkonium-sulfacetamide ILs were investigated for synergism and the biological studies data display no synergistic effect. It was also illustrated that in-situ IL based ibuprofen hydrogels systems could be manipulated via IL approach for topical application. These findings suggest the potential applicability of IL based formulations for topical delivery of drugs.
    • Development and validation of the vision-related dizziness questionnaire

      Armstrong, Deborah; Alderson, Alison J.; Davey, Christopher J.; Elliott, David B. (2018-05-29)
      Purpose: To develop and validate the first patient-reported outcome measure (PROM) to quantify vision-related dizziness. Dizziness is a common, multifactorial syndrome that causes reductions in quality of life and is a major risk factor for falls, but the role of vision is not well understood. Methods: Potential domains and items were identified by literature review and discussions with experts and patients to form a pilot PROM, which was completed by 335 patients with dizziness. Rasch analysis was used to determine the items with good psychometric properties to include in a final PROM, to check undimensionality, differential item functioning, and to convert ordinal questionnaire data into continuous interval data. Validation of the final 25-item instrument was determined by its convergent validity, patient, and item-separation reliability and unidimensionality using data from 223 patients plus test–retest repeatability from 79 patients. results: 120 items were originally identified, then subsequently reduced to 46 to form a pilot PROM. Rasch analysis was used to reduce the number of items to 25 to produce the vision-related dizziness or VRD-25. Two subscales of VRD-12-frequency and VRD-13-severity were shown to be unidimensional, with good psychometric properties. Convergent validity was shown by moderately good correlations with the Dizziness Handicap Inventory (r = 0.75) and good test–retest repeatability with intra-class correlation coefficients of 0.88. conclusion: VRD-25 is the only PROM developed to date to assess vision-related dizziness. It has been developed using Rasch analysis and provides a PROM for this under-researched area and for clinical trials of interventions to reduce vision-related dizziness.
    • Adherence to coronary artery disease secondary prevention medicines: exploring modifiable barriers

      Khatib, R.; Marshall, K.; Silcock, Jonathan; Forrest, C.; Hall, A.S. (2019-07)
      Background: Non-adherence to secondary prevention medicines (SPMs) among patients with coronary artery disease (CAD) remains a challenge in clinical practice. This study attempted to identify actual and potential modifiable barriers to adherence that can be addressed in cardiology clinical practice. Methods: This was a cross-sectional, postal survey-based study of the medicines-taking experience of patients with CAD treated at a secondary/tertiary care centre. All participants had been on SPM for ≥3 months. Results: In total, 696 eligible patients were sent the survey and 503 responded (72.3%). The median age was 70 years, and 403 (80.1%) were male; the median number of individual daily doses of all medicines was 6. The rate of non-adherence to at least one SPM was 43.5% (n=219), but 53.3% of reported non-adherence was to only one SPM. Statins contributed to 66.7% and aspirin to 61.7% of overall non-adherence identified by the Single Question (SQ) tool. In 30.8% of non-adherent patients (n=65), this was at least partly intentional. Barriers included forgetfulness (84.9%; n=186), worry that medicines will do more harm than good (33.8%; n=74), feeling hassled about medicines taking (18.7%; n=41), feeling worse when taking medicines (14.2%; n=31) and not being convinced of the benefit of medicines (9.1%; n=20). In a multivariate analysis, modifiable factors associated with overall non-adherence included being prescribed aspirin (OR: 2.22; 95% CI: 1.18 to 4.17), having specific concern about SPM (OR: 1.12; 95% CI: 1.07 to 1.18) and issues with repeat prescriptions (OR: 2.48; 95% CI: 1.26 to 4.90). Different factors were often associated with intentional versus unintentional non-adherence. Conclusions: Using appropriate self-report tools, patients share actual and potential modifiable barriers to adherence that can be addressed in clinical practice. Non-adherence behaviour was selective. Most non-adherence was driven by forgetfulness, concern about the harm caused by SPM and practical barriers.
    • Stone tools employed in prehistoric metal mining. A functional study of cobblestone tools from prehistoric metalliferous mines in England and Wales in relation to mining strategies by use-wear analysis and cobble morphometry

      Ottaway, Barbara; Pollard, A. Mark; Gale, David (University of BradfordDepartment of Archaeological Sciences, 1995)
      This is a study of cobblestone tools from metalliferous mine sites in England and Wales dated to the Bronze Age which were most probably used to extract copper ore. The site assemblages studied are from the Great Orme, Copa Hill in Cwmystwyth, Nantyreira, Parys Mountain and Alderley Edge. The majority of the tools are hammerstones used to mine and beneficiate metal ore. Some of these have been modified to facilitate hafting. The functional uses of these tools have been identified by the form and position of use- wear on a macroscopic level. The recording procedure encompasses cobble morphology, the degree, type and direction of use, breakage patterns, the reuse of tools and tool fragments and the classification of hafting modification. The possibility of tool specialization within tool types has been examined by the analysis of use-wear and cobble shape and size. The analysis of stone hammer size suggests that the Great Orme material is related to specific working techniques employed to extract ore from the different types of ore deposits. Ore comminution has been demonstrated to have been generally achieved by ‘block-on-block’ crushing with flat-sided hammers. Conclusions are draw on the overall efficiency of ore extraction in the Bronze Age and theories on the organization of mining are presented. The sedimentary form of the cobblestone tools has also been examined, including the identification of natural abrasion marks and features. At Cwmystwyth and the Great Orme possible sources of cobblestones have been studied in order to assess the nature of cobble selection.
    • Market sentiment and firm investment decision-making

      Danso, A.; Lartey, T.; Amankwah-Amoah, J.; Adomako, Samuel; Lu, Q.; Uddin, M. (Elsevier, 2019)
      While research on factors driving corporate investment decisions has blossomed, knowledge related to the Chief Executive Officer’s (CEO’s) market sentiment on investment decision outcomes is lacking. In this study, we extend the existing corporate finance literature by examining the underexplored issue of how CEOs’ market sentiment drives firms’ investment decisions. Capitalising on a large sample of US firms for the period 2004-2014, we uncovered some crucial observations. First, we found empirical support for our theoretical contention that market sentiment drives corporate investment decisions. Second, we established that, while financial flexibility induces managers to overinvest, the expectation of future profitability leads firms to underinvest during high sentiment periods. In addition, we uncovered that the 2007/08 financial crisis significantly impacted firm behaviour and realigned managerial decision-making. Thus, the sentiment-investment relationship is more pronounced during the crisis and the post-crisis periods. Our results are robust after accounting for the possibility of endogeneity and using alternative measures of both CEOs’ market sentiment and firm investment.
    • Short phosphate glass fiber - PLLA composite to promote bone mineralization

      Melo, P.; Tarrant, E.; Swift, Thomas; Townshend, A.; German, M.; Ferreira, A-M.; Gentile, P.; Dalgarno, K. (Elsevier, 2019)
      The clinical application of composites seeks to exploit the mechanical and chemical properties of materials which make up the composite, and in researching polymer composites for biomedical applications the aim is usually to enhance the bioactivity of the polymer, while maintaining the mechanical properties. To that end, in this study medical grade Poly(L-lactic) acid (PLLA) has been reinforced with short phosphate-based glass fibers (PGF). The materials were initially mixed by melting PLLA granules with the short fibers, before being extruded to form a homogenous filament, which was pelletized and used as feedstock for compression moulding. As made the composite materials had a bending strength of 51 MPa ± 5, and over the course of eight weeks in PBS the average strength of the composite material was in the range 20–50 MPa. Human mesenchymal stromal cells were cultured on the surfaces of scaffolds, and the metabolic activity, alkaline phosphatase production and mineralization monitored over a three week period. The short fiber filler made no significant difference to cell proliferation or differentiation, but had a clear and immediate osteoinductive effect, promoting mineralization by cells at the material surface. It is concluded that the PLLA/PGF composite material offers a material with both the mechanical and biological properties for potential application to bone implants and fixation, particularly where an osteoinductive effect would be valuable.
    • Molecular insights on the interference of simplified lung surfactant models by gold nanoparticle pollutants

      Hossain, S.I.; Gandhi, N.S.; Hughes, Zak E.; Gu, Y.T.; Saha, S.C. (2019-08-01)
      Inhaled nanoparticles (NPs) are experienced by the first biological barrier inside the alveolus known as lung surfactant (LS), a surface tension reducing agent, consisting of phospholipids and proteins in the form of the monolayer at the air-water interface. The monolayer surface tension is continuously regulated by the alveolus compression and expansion and protects the alveoli from collapsing. Inhaled NPs can reach deep into the lungs and interfere with the biophysical properties of the lung components. The interaction mechanisms of bare gold nanoparticles (AuNPs) with the LS monolayer and the consequences of the interactions on lung function are not well understood. Coarse-grained molecular dynamics simulations were carried out to elucidate the interactions of AuNPs with simplified LS monolayers at the nanoscale. It was observed that the interactions of AuNPs and LS components deform the monolayer structure, change the biophysical properties of LS and create pores in the monolayer, which all interfere with the normal lungs function. The results also indicate that AuNP concentrations >0.1 mol% (of AuNPs/lipids) hinder the lowering of the LS surface tension, a prerequisite of the normal breathing process. Overall, these findings could help to identify the possible consequences of airborne NPs inhalation and their contribution to the potential development of various lung diseases.
    • Long term evolution of the surface refractivity for arctic regions

      Bettouche, Y.; Kouki, A.; Agba, B.; Obeidat, H.; Alhassan, H.; Rodriguez, J.; Abd-Alhameed, Raed A.; Jones, Steven M.R. (2019)
      In this paper, local meteorological data for a period of 35 years (from 1979 to 2013) from Kuujuaq station have been used to calculate the surface refractivity, N and to estimate the vertical refractivity gradient, dN1, in the lowest atmospheric layer above the ground. Monthly and yearly variations of the mean of N and dN1 are provided. The values obtained are compared with the corresponding values from the ITU maps. The long-term trend of the surface refractivity is also investigated. The data demonstrate that the indices N and dN1 are subject to an evolution which may have significance in the context of climate change (CC). Monthly means of N show an increasing departure from ITU-R values since 1990. Yearly mean values of the dN1 show a progressive decrease over the period of study. Seasonal means of dN1 show a decrease over time, especially for summer. Such a trend may increase the occurrence of super-refraction. However, currently available ITU-R recommendations for microwave link design assume a stationary climate, so there is a need for a new modelling approach.
    • Laboratory experimental study of ocean waves propagating over a partially buried pipeline in a trench layer

      Sun, K.; Zhang, J.; Gao, Y.; Jeng, D.; Guo, Yakun; Liang, Z. (2019-02-01)
      Seabed instability around a pipeline is one of the primary concerns in offshore pipeline projects. To date, most studies focus on investigating the wave/current-induced response within a porous seabed around either a fully buried pipeline or a thoroughly exposed one. In this study, unlike previous investigations, a series of comprehensive laboratory experiments are carried out in a wave flume to investigate the wave-induced pore pressures around a partially embedded pipeline in a trench layer. Measurements show that the presence of the partially buried pipeline can significantly affect the excess pore pressure in a partially backfilled trench layer, which deviates considerably from that predicted by the theoretical approach. The morphology of the trench layer accompanied with the backfill sediments, especially the deeper trench and thicker backfill (i.e.,b≥1D,e≥0.5D), provides a certain degree of resistance to seabed instability. The amplitude of excess pore pressure around the trench layer roughly exhibits a left-right asymmetric distribution along the periphery of the pipeline, and decays sharply from the upper layer of the trench to the lower region. Deeper trench depth and thicker buried layer significantly weaken the pore-water pressures in the whole trench area, thus sheltering and protecting the submarine pipeline against the transient seabed liquefaction.
    • Investigation on scour scale of piggyback pipeline under wave conditions

      Yang, S.; Shi, B.; Guo, Yakun (2019-06-15)
      Laboratory experiments are presented to investigate the effect of different piggyback pipeline configurations on the morphology of local scour under wave conditions. Scour depth and width around the pipelines under regular and irregular waves are measured and analyzed for a range of pipeline and wave conditions; such as the spacing between two pipes (G), gap between the main pipe and seabed (e), pipe diameter (D), wave height (H) and period (T). Experimental results reveal that both the scour depth and width around piggyback pipeline is much larger than those around single pipe under the same wave conditions. Scour depth increases with the increase of the Keulegan-Carpenter (KC) number and decreases with increase of G and e. When e exceeds 0.5D, scour depth tends to approach 0.When spacing G is greater than 0.4D, the destabilization from small pipe to large one is greatly reduced, resulting in scour depth around piggyback pipeline being close to that around single pipe. Similar to scour depth, scour width broadens with the increase of KC number increasing and decreases with the increase of G. Experiments also show that the effect of e on scour depth is greater than that of G under the same test conditions, while their impact on scour width is opposite. Furthermore, scour width under irregular waves is extended slightly compared with regular wave for otherwise the identical conditions.