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Project management methods against failure factors in complex infrastructure projects:the Netherlands view
No full textThe purpose of this research is to examine the relationship between effective project management approaches and the causes of project failure in the infrastructure sector. Therefore, existing research regarding the failure factors and project management in the infrastructure are analysed. A systematic literature review is conducted, followed by detailed interviews. Based on 49 articles that were extracted using quality assessment criteria, the authors identified a detailed list of factors that barricades the success of infrastructure projects in the Netherlands. With the help of seven interviews, authors found that the main factors leading to project failure are ‘scope changes’, ‘coordination and communication problems’, and ‘poor project structure and scheduling problems’. Additionally, we also identified frequently used project management approaches by project managers. Based on this information, a matrix is established that shows which causes can be minimised using a specific project management approach. These findings will help project managers in the infrastructure industry select the most suitable project management approach that aligns with their needs.</p
ASO Visual Abstract:Surgery for Classic, Pleomorphic and Nonclassic Lobular Carcinoma In Situ Surgery Rate, Risk of Upstaging and Short-Term Follow-Up
No full textRiccati equations and LQ-optimal control for a class of hyperbolic PDEs
Get PDFWe derive an explicit solution to the operator Riccati equation solving the Linear-Quadratic (LQ) optimal control problem for a class of boundary controlled hyperbolic partial differential equations (PDEs). Different descriptions of the system are used to obtain different representations of the operator Riccati equation. By means of an example, we illustrate the importance of considering an extended operator Riccati equation to solve the LQ-optimal control problem for our class of systems
Prevalence and severity of pain, anxiety, stress, and sleep disturbances among surgical patients:A nationwide single-day multicentre flash mob study
Get PDFBackground Patient-reported outcomes (PROs) are subjective health indicators including pain, anxiety, stress, and sleep disturbances. Despite their frequent occurrence in the perioperative period and potentially severe consequences for postoperative recovery (for example prolonged length of hospital stay, cardiovascular events, development of chronic pain), these are not acknowledged as complications and their exact prevalence remains unclear. This study aims to assess the prevalence and severity of pre- and postoperative pain, anxiety, stress, and sleep disturbances among surgical patients. Methods A nationwide single-day multicentre cross-sectional flash mob study was conducted in 29 Dutch hospitals. Adult surgical patients with an expected hospital stay of at least one night were included. Patients admitted for neurosurgery, cardiothoracic surgery, or orthopaedic surgery were excluded. Primary outcomes were self-reported pain, anxiety, stress, and sleep disturbances, as assessed with the Numeric Rating Scale, Visual Analogue Scale for Anxiety, Perceived Stress Scale, and the adapted Patient-Reported Outcome Measurement Information System respectively. Results Of the 1077 eligible patients, 733 (68%) patients (mean age of 64 ± 15.9 s.d. years, 51.8% male) completed participation. Moderate to severe pain was prevalent in 509 patients (69.7%) and occurred most frequently post-surgery. Anxiety occurred in 278 patients (38.1%) and was more prevalent preoperatively. Moderate to severe stress was reported by 272 patients (37.8%) with similar findings pre- and post-surgery. Sleep disturbances were prevalent in 440 patients (64.1%). Pain and anxiety were more severe in females. Sleep disturbances were more severe in patients with lower socioeconomic status. Conclusion Pain, anxiety, stress, and sleep disturbances are highly frequent complications among surgical patients in Dutch hospitals. Considering the prevalence and severity, we suggest implementing these relevant additional measures for PROs as indicators for routine postoperative evaluation to facilitate their management.</p
On the Approximate Component Mode Synthesis method for the approximation of the Helmholtz equation
No full textThis dissertation introduces and investigates an extension of the Approximate Component Mode Synthesis (ACMS) method, originally developed for elliptic partial differential equations, to the two-dimensional heterogeneous Helmholtz equation. The ACMS method is a multiscale approach that employs a non-overlapping domain decomposition to split the numerical solution into two independent components: local Helmholtz problems, which can be solved in parallel, and a global interface problem, addressed using locally supported basis functions constructed from eigenmodes and suitable extensions. For a fixed decomposition, the method achieves algebraic convergence, and in some cases even super-algebraic convergence, without requiring oversampling.Next, the thesis presents an implementation of the ACMS method using high-order hp-finite elements within the open-source package NGSolve, enabling more accurate eigenfunction approximations and improved computational efficiency. Numerical experiments show that high-order elements significantly enhance the convergence rate of the method, particularly at higher wavenumbers, and effectively mitigate the pollution effect commonly observed with linear elements. The implementation demonstrates both computational efficiency and straightforward parallelization. The number of edge modes required for convergence scales linearly with the wavenumber, with rapid initial error decay and low sensitivity to the domain decomposition. The method is applied to large photonic crystals with defects, where system sizes remain moderate, allowing the use of sparse direct solvers.Finally, the ACMS framework is extended to cases with discontinuous material parameters aligned with the domain decomposition interfaces. In these lower-regularity settings, refined error estimates are derived and numerically validated, establishing convergence rates even in the presence of singular points caused by corners in the material coefficients. Numerical results further show that, although not covered by the theoretical bounds, higher convergence rates are achieved locally away from the critical regions
Exploring professional vision of vet students and tutors:noticing, evaluating and reasoning about practice
Get PDFIn dual vocational education and training (VET) programs, students learn across school and work contexts. Educators in both these contexts reside in different socio-cultural practices and can have different or even contradicting views on practice, influencing their guidance. In this study, we used the concept of professional vision to explore differing views on practice between participants with various educational roles, namely students, school teachers and workplace supervisors. In total, 11 students, 11 school teachers and seven workplace supervisors were asked to view the same set of five videos showing apprentices in the domain of underground infrastructure performing domain-specific tasks. Participants were asked to explain what they noticed in the videos and evaluate the apprentices’ performance. The data analysis consisted of a mixed-method approach. We quantitatively compared how educational roles viewed and evaluated task performance, followed by a qualitative ventriloquial analysis of their reasoning. Our findings highlight the diversity in professional vision among participants. Participants focused on different elements of practice, evaluated the same elements differently and showed variations in their reasoning. However, this could only be partly explained by their educational role. These findings suggest a need to prepare VET students for the different views of practice they will encounter during their careers, ultimately forming their well-founded professional vision.</p
Strategic programmes for circular construction: lessons from three public clients
Get PDFStrategic programmes are frequently employed by organisations to drive transformational change, particularly when sectors pursue systemic shifts, such as the circularity transition. However, despite their potential, these programmes often fail to effect lasting change within their parent organisations, with outcomes remaining disconnected. This study examines how programme integration mechanisms shape organisational transformation in circularity-oriented change programmes. Several mechanisms were identified through a comparative case study of Dutch public construction clients. The findings suggest that isolating such programmes from the parent organisation hinders organisational transformation. Instead, the early incorporation of integration mechanisms is essential to facilitate both learning and unlearning processes, ensuring the effective and sustainable adoption of circular practices. Moreover, findings show that temporal alignment emerges as a decisive factor in a programme’s transformative capacity, as mismatches between programme and organisational learning trajectories can limit systemic impact. These insights contribute to strategic programme literature by demonstrating how these programmes can, depending on their formal and informal mechanisms, promote or stall transformative change
A Study of Structure-Property Relationships in Silica-filled SSBR/BR Compounds
No full textThis thesis explores structure – property relationships in silica-filled rubber compounds for passenger car tire treads. The work focuses on how polymer microstructure, functionalization, blend ratios, and filler loading influence rheological, mechanical, and dynamic properties, with the goal of balancing rolling resistance, wet traction, and abrasion resistance – the “magic triangle” of tire performance. Using solution styrene–butadiene rubber (SSBR) and butadiene rubber (BR), both single-polymer and binary blend systems were systematically studied. Key findings show that polymer functionalization enhances filler-polymer interactions and silica dispersion, reducing hysteresis and improving rolling resistance. Blending SSBR with BR provided a synergistic improvement in elasticity, wear resistance, and traction. Laboratory-scale correlations confirmed that LAT100 is a reliable predictor of wet grip and abrasion. The optimal formulation – functionalized SSBR 4602 blended with BR (70/30) and filled with 75-80 phr silica – achieved a well-balanced performance, offering practical design guidelines for next-generation high-performance tire tread compounds
Vessels in the void:Microtissue packing for vascular integration in engineered tissues
No full textThe field of tissue engineering aims to restore, repair or replace damaged tissue. One of the most researched approaches to achieve this goal is to engineer (parts of) tissue using combinations of materials and cells to restore the function of the damaged tissue. Whereas a number of studies have shown success using small engineered tissues, large implants have typically failed due to inhomogeneous nutrient distribution, leading to starvation and necrotic core formation and, ultimately, implant failure. To enable implant survival of larger (e.g. > cm3) engineered tissues, new solutions are needed to improve nutrient distribution. A common approach is to mimic the vascular system in the human body, for example by self-assembly of vascular cells or bioprinting vascular-like channels within engineered tissues. In this manner, simple channel networks can be created, however they lack the resolution and density of capillary networks, the smallest vessels which ensure fully homogeneous nutrient distribution within tissue. Thus, there is a need for new approaches to prevascularize engineered tissues and mimic the hierarchical vascular networks found in vivo.This thesis describes i) the development of engineered tissues with inherent capillary-like networks through the bottom-up assembly of cell-laden microfluidically generated living building blocks; ii) the combination of microgel assembly and aqueous two-phase based 3D bioprinting to generate hierarchical channel networks that mimic the vascular tree; iii) the incorporation of insulin releasing beta cells within bottom-up assembled engineered tissues for the treatment of diabetes and iv) a new device to generate cell-laden microfluidic building blocks ranging from the size of a single cell to that of cellular aggregates.Taken together, this thesis describes a variety of methods as well as tools to enable the generation of prevascularized tissues to facilitate the clinical translation of cubic centimeter sized engineered tissues
Knowledge extraction and footprint generation using the GeoSpace Body of Knowledge
Get PDFKnowledge footprints are visualisations of personal and organisational expertise. They can be used for capturing, sharing and matching expertise in the context of promotion, research exposure, project collaboration, etc. We have developed a method for creating footprints in the geospatial domain, based on resources created by persons and organisations and using the GeoSpace Body of Knowledge as a shared, standardised vocabulary. We deployed an NLP-based keyword extraction method to annotate resources with GeoSpace BoK concepts and constructed a knowledge graph to connect these BoK concepts to personal or organisational profiles. Footprints are then created by querying the knowledge graph and visualizing the results. Initial tests have been carried out to validate the generated footprints