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Impact of Human Resources Management Practices on Seaport Competitiveness: A Case of Nigerian Seaports
No full textDespite numerous efforts at modernising Nigeria's seaports, they remain inefficient. Many studies have been conducted to find the root cause of the inefficiency and many solutions have been recommended based on findings. The findings have variously pointed to infrastructural decay, inadequacy, and lack of modern seaport technologies as root causes of inefficiency at the seaports. Surprisingly, however, the proffered solutions have all failed to solve the lingering inefficiency and poor performance of the seaports. This suggests that, apart from the challenges associated with poor infrastructure, efforts must be directed at other areas to identify and explain the persistent inefficiencies that have defied many solutions at the seaports. This study, therefore, focusses on identification of the key underlying issues by examining whether there is a relationship between seaport inefficiency and human resources management (HRM) practices of the seaports. Case study approach was adopted, and qualitative data was collected, using semi-structured interview protocol. A qualitative content analysis (QCA) was conducted along with an NVivo program analysis. A total of 34 respondents were interviewed from four categories of key seaport stakeholders comprising of 33 male and one (1) female. Among the respondents are 19 seaport managers (SM), three (3) seaport union executives (SUE), four (4) Customs Area Controllers (CAC) and eight (8) shippers/freight forwarders (SFF). Findings reveal that HRM practices of the seaports are not fully aligned with the business objectives of the Nigerian Port Authority (NPA) mainly due to unfair recruitment and unfair promotion practices. The findings also indicate that the working condition of staff is average and, consequently, staff morale, loyalty, commitment, and productivity are also average. Technologically, findings show the level of technological implementation at the seaports is at best average, as only basic technologies are available for seaport operations. On Corporate Governance (CG), the study finds the appointment of the Board of Directors of the seaport is mainly political. The Board is, therefore, not fully independent because of external political influences. On the overall cost of clearance at the seaports, findings indicate that the official seaport charges at the seaports are reasonable and competitive, but illegal charges extorted from customers make overall clearance cost uncompetitive. Similarly, while the speed of clearing cargo has improved over the years, the level of customer service provided is average. Overall, the findings indicate that modern infrastructure/technology in themselves will not yield any major positive impact in terms of improve competitiveness for the Nigerian seaports without commensurate high-quality governance and human resources (HR) practices identified and addressed in this study.</p
Elucidating the Mechanisms Driving the Pathophysiology of HIV-Associated Neurocognitive Disorders
No full textGlobally, approximately 40% of people living with human immunodeficiency virus (HIV) on antiretroviral therapy (ART) develop a form of HIV-associated neurocognitive disorder (HAND). Viral persistence and associated neuroinflammation, in addition to ongoing systemic inflammation, are thought to play crucial roles in neuropathology. However, the cellular immune environment in the brain of virally suppressed people with HIV (PWH) is unclear.
Here we characterised viral persistence and immune activation in the brain during chronic HIV infection using a simian immunodeficiency virus (SIV) non-human primate (NHP) model and autopsy frontal cortex tissue from PWH. Additionally, matched gut and frontal cortex tissue from SIV+ NHPs and an SIV-uninfected model of chronic gut damage were utilised to determine whether gut damage can impact neuroinflammation alone, in the absence of SIV infection. NHP Cohort: SIV+ NHPs sacrificed during acute (n=4), chronic (n=12) or virally suppressed (VS) SIV infection (n=11) and SIV-uninfected NHPs with (n=4) or without experimentally induced gut damage (n=4). Human Cohort: Human autopsy brain tissue from non-VS (nVS; n=7) or VS PWH (n=10). HIV/SIV viral RNA/DNA and immune activation/inflammation were quantified at a cellular level in matched gut tissue from the SIV cohort and frontal cortex tissue from each cohort using DNA/RNAscope, multiplex immunofluorescence, droplet digital PCR and the intact proviral DNA assay (IPDA), where appropriate.
SIV DNA+ and RNA+ cells were detected in the frontal cortex and gut tissue of all SIV+ groups tested. Additionally, the frequency of viral DNA+ cells were not reduced in the frontal cortex or gut in VS NHPs (P< 0.05), supporting the presence of a stable viral reservoir in the frontal cortex and gut tissue that is not reduced by ART. SIV+ NHPs had enhanced type I interferon-induced MX dynamin like GTPase 1 (MX1), oxidative stress and transforming growth factor beta 1 (TGFβ1) responses, expansion of activated astrocytes and myeloid cells as well as reduced blood brain barrier (BBB) integrity compared to uninfected NHPs, which persisted despite ART (P<0.05 for all). Surprisingly, BBB breakdown and neuroinflammation correlated strongly with measures of gut inflammation, but not brain viral load. Similar immune activation profiles were present in the frontal cortex tissue of the SIV uninfected animals with chronic gut damage, indicating that persistent damage to the gut alone can contribute to immune activation in the frontal cortex independent of SIV infection.
Comparative analysis in human autopsy frontal cortex tissue from PWH showed similar levels of total HIV DNA and intact proviral DNA in nVS compared to VS PWH (P>0.05 for both), reflecting a stable CNS reservoir of HIV that persists despite viral suppression. Similar to findings in NHPs, frontal cortex tissue from PWH had enhanced Mx1 and tumour necrosis factor alpha (TNFa) responses and expansion of activated myeloid cells that persisted despite viral suppression (P<0.05 for all). In contrast to the limited relationship between local CNS virus and neuroinflammation in NHPs, a strong positive correlation between intact HIV DNA and Mx1+ cells were present in the frontal cortex of VS PWH (p<0.05). While there were no significant correlations present between HIV DNA in the frontal cortex and neurocognitive domain scores, both Mx1 and TGFβ1+ myeloid cells correlated with poorer scores in the attention domain (P<0.05 for both).
Our findings in NHPs provide the strongest evidence to date that the frontal cortex of SIV+ NHPs remains in an activated state despite long-term ART treatment and that gut damage can induce neuroimmune activation. In humans, the presence of intact virus rather than total HIV DNA was associated with increased neuroinflammation, which was in turn associated with poorer neurocognitive outcomes, highlighting the ongoing effects of HIV reservoirs in VS PWH. Overall, the data presented demonstrates the frontal cortex as a site of viral persistence and chronic immune activation in PWH and SIV+ NHPs despite long-term viral suppression.</p
Structural Topology Optimisation using Reaction Diffusion based B-spline Level Set Method
No full textWith the rapid progress in additive manufacturing, structural topology optimisation has shown significant promise for crafting structures that are simultaneously lightweight and sturdy. However, traditional methods of structural representation may result in zig-zag boundaries, posing a risk of inaccuracies in structures produced through additive manufacturing. Thus, this project seeks to introduce an innovative structural topology optimisation approach and apply it to tackle diverse engineering challenges with unique objective functions.
Inspired by isogeometric analysis, the primary purpose of this thesis is to avoid the drawbacks of geometric dependence on control points and develop a novel parametric level set method based on the framework of B-splines. Therefore, the B-spline coefficients are chosen to be the design variables, and the B-spline based level set function is applied to generate the zero-level contour. In order to converge faster, a reaction diffusion updating scheme is utilised. All the sub-topics of this thesis are built based on the reaction-diffusion based B-spline level set method. The brief introductions of the five sub-topics are listed as follows:
The first sub-topic is to propose the novel structural topology optimisation method. The B-spline level set representation framework is presented from B-spline curves to B-spline surfaces. Then, the updating scheme for B-spline coefficients is introduced and the predetermined matrices are created. Next, the algorithm is extended to 3D situations. 2D and 3D numerical examples show the robustness and efficiency of the proposed algorithm.
The second sub-topic is to explore the potential of combining RDBLS with body-fitted mesh. The level set-based optimisation method generally uses the rectangular/hexahedral mesh in finite element analysis despite its zero-level contour crossing these elements. Hence, adaptive triangular mesh is employed to improve the similarity of the finite element model with the smooth structure presented by the level set method. Also, the parametric level set function is still a linear combination of cubic B-spline basis functions, which can increase optimisation flexibility and structural smoothness.
The third sub-topic is to propose a simple and compact MATLAB code for beginners interested in exploring the parametric level set method. Combining the advantages of the B-spline-based level set function and the reaction-diffusion updating scheme, the proposed algorithm achieves a smooth structural profile and shows fast convergence. Additionally, an extension code by use of repeated knots is also provided to deal with the boundary connection of neighbouring design domains.
The fourth sub-topic is to apply the abovementioned MATLAB code in designing porous materials with prescribed strength. The inverse homogenization method can tailor some mechanical and physical effective properties by laying out materials in a periodic representative volume element. However, studies on strength design are yet to be developed because of the difficulties in numerically retrieving its value. Unlike traditional asymptotic homogenization, the fast Fourier transform-based homogenization method based on the augmented Lagrangian approach uses a Green operator in the frequency domain to replace time-consuming finite element analysis and inherently meet the periodic boundary conditions. Thus, it is developed in this work to retrieve material strength in terms of the von Mises yield criterion.
The fifth sub-topic is to extend the abovementioned strength design in bone scaffold design. Large bone defect is a major challenge in orthopaedic surgery, where bone scaffold shows great potential to tackle osseous defects. However, the commonly used scaffold materials, such as metals and alloys, have much higher stiffness and mismatched strength than natural bones. The equivalent Young's modulus and yield stress must be adjusted when using these bulk materials to avoid stress shielding. Therefore, a multi-objective problem is generated to satisfy the requirements of stiffness and strength simultaneously. The inverse homogenisation is achieved by reaction diffusion-based B-spline level set method, where FFT-based homogenisation is applied in both stiffness design and strength design. The 2D & 3D numerical examples are displayed to show the effect of mechanical properties mimicry.
Overall, the research outcomes demonstrate that the proposed reaction diffusion-based B-spline level set method can be applied in structural topology optimisation and export smooth boundaries and display highly efficiency. Applications in 3D complex structures, strength design, bone scaffold design prove that it has strong compatibility to solve different practical problems.</p
A Novel Nanocomposite for Building Façades
No full textModern building facades provide an innovative solution for designing high-performance building envelopes with increased energy efficiency and outstanding aesthetic appeal. The necessity for high thermal and acoustic insulation has led to the inclusion of significant amounts of combustible materials in many contemporary facade systems. In addition, factors such as cost-effectiveness, availability, and ease of manufacture also influence the choice to incorporate combustible materials. As a result, concerns have been raised about fire safety, specifically the possibility of a fire spreading throughout the building and to nearby structures. The issue of combustible envelope of the building has recently come to light as a significant construction challenge.
This PhD thesis provides a comprehensive review of the current state of common facade systems, highlighting both their pros and cons. It also covers cladding materials, fire testing methods, and fire testing simulations used in this PhD. The literature review reveals the lack of a novel cladding material to enhance the fire performance of facade systems, a gap in research on the fire behaviour of three-dimensional (3D) glass fibre-reinforced polymers (GFRP) integrated with flame retardants and nanomaterials for facade applications, and limited utilisation of artificial intelligence (AI) in composite material design. The research presented in this thesis aims to address the aforementioned research gaps.
This PhD project aims to develop innovative nano ceramic-based composite cladding material designed for building facades using state-of-the-art 3D GFRPs and phenolic resin. The 3D GFRP cladding offers several advantages by utilising ceramic-based flame retardants, including high thermal resistance, reduced flammability, and thermal stability when exposed to fires. The Taguchi Design of Experiment (DoE) is proposed for optimisation of the cladding material design, incorporating multiple relevant factors and levels in the manufacturing process. The four manufacturing design factors considered in the Taguchi DoE are the flame retardant type (Ceram-FR, ATH-FR, and 3DC-FR), percentage of flame retardant (0.0, 2.5, and 5.0 wt.%), curing regime (60 °C for 2 hours, 90 °C for 2 hours, and 60 °C for 1 hour followed by 90 °C for 1 hour), and dispersion technique (magnetic stirring, three roll milling, and ultrasonication), with each factor having three levels.
A scanning electron microscopy (SEM) analysis was used for morphological characterisation of the polymer nanocomposites (without fibreglass fabric) and fibre-reinforced nanocomposite samples to investigate the effectiveness of different dispersion methods and curing regimes. In-plane tension, and in-plane and out-of-plane compression tests were conducted in reference to ASTM D3039, ASTM D3410, and ASTM C365-00, respectively, to evaluate the mechanical properties of the fibre-reinforced composites. Fire-under-tension load tests were conducted at two heat flux levels (19 and 40 kW/m²) within this project. The test results indicate that, under a heat flux of 19 kW/m², the fibre-reinforced composite with 5.0 wt.% Ceram-FR dispersed using magnetic stirring and cured at 60 °C for 2 hours, could maximise the failure time and failure temperature. For samples exposed to a heat flux of 40 kW/m², the analysis revealed the best performing formulation to be 5.0 wt.% ATH-FR dispersed using ultrasonication and cured at 60 °C for 1 hour followed by 90 °C for 1 hour.
An investigation into the thermal behaviour and fire performance of the 3D GFRP cladding is undertaken using thermogravimetric analysis (TGA) and cone calorimetry conducted in accordance with the ISO 5660-1 standard. The TGA analysis of the nanopolymers showed that samples containing 5 wt.% Ceram-FR experienced the least weight loss at 850 °C compared to other polymer nanocomposites in both air and nitrogen environments. The optimised formulation (denoted as C10) for minimising critical response parameters of the 3D GFRP cladding during cone calorimetry, such as the ratio of peak heat release rate (PHRR) to the time to reach the peak, the ratio of PHRR to time to ignition, total heat release (THR), and effective heat of combustion, was found to include 5 wt.% Ceram-FR dispersed using magnetic stirring and cured at 60 °C for 1 hour followed by an additional 1 hour at 90 °C. The optimised 3D GFRP cladding demonstrated improved fire resistance, resulting in a lower PHRR and total THR compared to the nine cladding formulations fabricated using Taguchi DoE.
This project also involves the development of AI-based simulations using machine learning algorithms to predict the performance of the 3D GFRP cladding when exposed to fires. The AI- predicted results can reproduce the experimental heat release rate data from the cone calorimeter test. Furthermore, the model is a useful tool to assist in calibrating the multiple input parameters required to analyse the 3D GFRP cladding using Fire Dynamics Simulator (FDS), including heat source and pyrolysis reaction properties.
An FDS simulation study on a full-scale façade constructed from the optimised 3D GFRP cladding (C10) was conducted in accordance with the BS 8414-2 standard. The fire performance of the 3D GFRP façade system obtained from cone calorimetry was compared against the performance criteria prescribed in AS 5113 for the BS 8414-2 simulation. The results indicate that the façade system using the optimised 3D GFRP cladding could meet most of the prescribed performance criteria. The outcome for the criterion concerning internal temperatures measured at 5 m above the fire source was unclear due to modelling assumptions. It is essential to note that these simulation results should be considered as a preliminary assessment. A comprehensive full-scale façade system test is recommended to validate the FDS findings.
The research presented in this PhD thesis contribute to the understanding of the fire performance of flame retardant 3D GFRP cladding materials designed for façade applications. New insights into the mechanical response and survivability of these composite cladding systems during fire were revealed. The research also offers valuable insights into the incorporation of AI in composite material design and the calibration of FDS models, significantly contributing to the development of AI-based modelling in predicting composite material properties during fire exposure.</p
Digital Sales Transformation: What are the Consequences of the Evolution of Digital Technologies on the B2B Sales Function?
No full textThe adoption of digital technologies has radically changed the B2B sales process. Various digital technologies including CRM, social media, mobile technologies, artificial intelligence, and digital platforms now play an important role in modern selling practice. However, previous literature provides relatively mixed and even paradoxical insights into the consequences of digital technology adoption for sales organizations and their customers. Therefore, the aim of this study is to explore how the evolution digital technologies has transformed the sales function, including its consequences for salespeople, managers, and the organization. This thesis is based on three original papers, that include one literature review and two empirical studies. The empirical studies are based on 59 qualitative interviews in the Australian building industry and examine digital technology adoption inside sales organizations and within business networks. The findings show 1. how the sales function has evolved
because of digital technologies, 2. How the consequences of these changes impact actors at different levels within sales organizations, and 3. How the consequences impact firms at the network level. This study contributes to the sales management and digital transformation literatures by providing a more holistic understanding of the diverse consequences of digital technology adoption in sales</p
Performance of 3D-Printed Cementitious Composites With Recycled Waste Materials
No full text3D concrete printing (3DCP) has developed rapidly over the last decade and the interest in sustainable cementitious composites by incorporating recycled waste materials has also increased in 3DCP. Regarding the research works on 3DCP, the main focus has been put on the rheological and hardened mechanical properties, in contrast to relatively limited research outputs on the correlation between mechanical and microstructural properties of 3D-printed cementitious composites. Furthermore, unidirectional printing patterns have been widely utilised for the printing process. However, voids due to underfilling between extruded filaments may occur depending on the fresh properties of materials, leading to negative impacts on the overall mechanical performance. Therefore, it is also expected to modify the unidirectional pattern to enhance the mechanical properties of 3D-printed cementitious composites potentially.
This work aims to develop a solid understanding of the relationship between the mechanical properties and microstructural features of 3D-printed cementitious composites containing different categories of recycled waste materials. Three kinds of recycled waste materials are considered for this work, including recycled glass particles, recycled crumb rubber and recycled carbon fibres. The research scope and experiment plan are determined in the first section of this work. A laboratory-scaled extrusion-based printer is used to fabricate 3D-printed cementitious composite specimens. The fresh properties of mortar materials, including slump flow and buildability, are evaluated prior to mechanical tests to ensure the materials' printability. The mechanical properties of 3D-printed specimens to be evaluated mainly consist of compressive and flexural strengths. The microstructural features include the void structures inside printed specimens and the microstructural morphology of cement matrix, which are investigated via X-ray micro-computed tomography (μCT) and scanning electron microscopy, respectively.
The second section of this work focuses on the flexural properties of 3D-printed cementitious mortar specimens containing 50 wt.% recycled glass particles as the partial replacement of sand. Two grades of recycled glass are used, including the coarse and fine grades with the median size of 796 and 367 μm, respectively. The mortar specimens are 3D printed with the conventional unidirectional pattern. As for the three-point test, the mid-point load is always along the layer deposition direction. When the beam span is parallel to the printing direction, the flexural strengths experienced a decrease with the addition of recycled glass, which is correlated to the μCT analysis results that the proportion and morphology of voids affect the crack propagation. When the beam span is perpendicular to the printing direction, the addition of recycled glass positively influences the flexural strength. Such an opposite trend can be correlated to the analysis results of μCT and SEM, showing the strength improvement and the way the crack propagates depends on the glass particles situated alongside the crack path.
After that, the third section of this work moves on to the compressive properties of 3D-printed cementitious mortar specimens containing 15 wt.% recycled crumb rubber as the partial replacement of sand. The crumb rubber is pre-coated with cement paste, with three cement-to-rubber ratios (C/R) considered (0.25, 0.4 and 0.55). The 3D-printed mortar specimens are fabricated with the unidirectional pattern. The anisotropic behaviour in compression is more obvious for the medium-to-high C/Rs compared to the low C/R. According to μCT analysis, the mechanical anisotropy of printed mortar with medium-to-high C/Rs could be correlated with two factors: void morphology and void orientation relative to the direction of external compressive loads. As for the low C/R, the insufficient bonding between the rubber surface and cement matrix, rather than the void structure, is considered more critical to influencing the mechanical properties of printed mortar.
The fourth section investigates the compressive and flexural properties of 3D-printed mortar specimens with recycled carbon fibres (up to 2 vol.%). Unlike the previous two studies, this study further modifies the unidirectional pattern by introducing the layer offset strategy and explores the effects of layer offset on the mechanical and microstructural properties of 3D-printed specimens. It is found that when the degree of layer offset increases, the compressive and flexural strengths along all testing directions are improved. Meanwhile, the anisotropic level of compression in 3D-printed specimens also decreases as the layer offset degree increases. μCT analysis shows that the internal void structures comprise channel and micro voids. The geometry regularity of channel voids is lower than that of micro voids. Varying the layer offset degree can change the total porosity and volumetric proportions of channel voids, thus affecting the level of stress concentration around the voids themselves and the mechanical properties. The experiment results indicate that layer offset can be considered a potential method to enhance the mechanical performance of 3D-printed cement mortar specimens containing recycled waste materials.
Considering the importance of μCT analysis on the void structure analysis of 3D-printed concrete, the fifth section further provides an extended review of applying X-ray μCT analysis to investigate different categories of concrete, followed by the machine learning application on improving the phase segmentation accuracy from the μCT sliced images of concrete. Based on the review outcomes, the machine learning models are recommended to be integrated with the X-ray μCT analysis of 3D-printed cementitious materials in future studies to accurately capture different phases of concrete materials and understand the inherent properties of 3D-printed materials.
In summary, this research provides new insights into the mechanical performance of 3D-printed cementitious composites with recycled waste materials from the perspective of microstructural characteristics. Through this doctoral research, the mechanical properties of 3D-printed specimens are found to be closely related to the internal void structures and microstructural morphology of cement matrix, providing fundamental suggestions and guidelines for potentially enhancing the mechanical properties of 3D-printed cementitious specimens in future research. The experiment results also demonstrate that incorporating recycled waste materials into cementitious materials and improving the mechanical properties of printed specimens via modifying the printing pattern are practical solutions for 3D concrete printing.</p
I Used to Walk so Softly on this Land
No full textI Used to Walk So Softly on this Land explores my holistic and interrelated approach to creative practice. Through my Indigenous standpoint, the creative practice research focuses on concepts like Blood Memory, ceremony and culture, contemporary and historical mark-making, and ‘not leaving traces’. Privileging repetitive learning and relational ways of knowing, the dissertation is written through auto-ethnographic reflection and verbatim interview to complement the core creative practice through a connected series of artworks: The Boy on the Side of the Road and the Bush Fire series. As a way to continue connection to Country, these paintings conceptually and materially connect my experience of Australian bushfires to the idea of an uncontrollable child. Further, Talking Circles are explored as a collaborative and cultural form of making and sharing of knowledge through the interrelation of yarning, creative practice, and community. Through the visual, written and oral narration of stories of both trauma and resilience, I Used to Walk So Softly on this Land makes contributions to both contemporary art and Indigenous studies while persistently challenging institutional hierarchies of knowledge.Aboriginal and Torres Strait Islander people should be aware that this thesis and associated project files may contain the images, voices or names of people who have since passed away. </p
Effects of Practioner's Mood on External Idea Evaluation: Implications for Open Innovation
No full textWhat causes ineffective external idea evaluation in open innovation (OI) still remains an unsolved puzzle, with most such studies focused on creative idea generation or using samples of untrained evaluators. To help better understand the microfoundations of OI, this article examines the effects of mood on external idea evaluation using a practitioner sample. Drawing on “mood-as-an-input” theory, in two behavioral experiments using music induction, cognitive tasks, and idea framing, we test how one's mood affects the innovativeness rating of an externally developed idea, and examine whether this effect is stable within a mood state regardless of the level of creativity (high and low) of an idea. We found that people in happy and sad mood conditions differ in their evaluation of the same external idea, which is explained by differences in assessment of creativity of an idea and not the perceived certainty of its success. Moreover, a given mood state does not affect how ideas low in creativity are rated in their innovativeness, compared to ideas high in creativity. This article by investigating effects of mood within an OI process augments individual level OI literature, while informing the ways external idea evaluation can be managed toward enhancing OI potential