Modelling of flow around hexagonal and textured cylinders

The flow regime around a hexagonal polygon with low Reynolds numbers Re<200 is numerically investigated in two different orientations namely face-oriented and corner-oriented. The basic flow characteristics, including drag coefficient, lift coefficient, Strouhal number and critical Reynolds number of the hexagonal cylinders, are calculated using 2D transient numerical analysis. Within the studied range of Re, the predicted lift coefficient and Strouhal number of the face-oriented hexagon were higher than those of the corner-oriented hexagon. In contrast, the predicted drag coefficient and critical Reynolds number of the corner-oriented hexagon were greater than those of the face-oriented. Flow characteristics of a novel textured geometry are also studied using 3D transient analysis. The Strouhal number St of the textured geometry was found to be in between the St of both the hexagonal cylinders, and its lift coefficient is lower than that of the hexagonal cylinders

Appropriateness of physicians' lumbosacral MRI requests in private and public centers in Tehran, Iran

Background: Back pain is a common patients' complaint, and its etiology is important because of different potential treatment approaches (based on causes). For a better diagnosis, magnetic resonance imaging (MRI) is widely used in clinical settings that may result in inappropriate requests. This study aims to evaluate the appropriateness of the lumbosacral MRI requests in patients with back pain in two public/referral and private imaging centers in Tehran. Methods: In this cross-sectional study, 279 patients from both centers were recruited in 2014. A checklist was developed based on the internationally recognized clinical guidelines (NICE, and AHRQ) for determining the indications. An expert panel of related specialties finalized them. Patients' demographic and some anthropometric measures, as well as MRI reports, were collected. Results: The mean±SD age of patients was 47.9±14.78 years with a dominance of females (M/F=38.4/61.6). About 77 (n=214) of lumbosacral MRIs were requested in accordance with the guidelines. Indicated MRI requests were significantly higher in the private imaging center (p=0.019, OR=2.087, CI 95: 1.13-3.85). In the private center, 80.6 and in the public center, 70.4 of the MRI requests were in accordance with the guidelines. Conclusion: The proportion of non-indicated MRI requests based on the valid guidelines is about 1/4 of all requests that is compatible with some other studies mostly from developed countries

Formulating a Strategic Plan for BIM Diffusion within the AEC Italian Industry: The Application of Diffusion of Innovation Theory

The importance of digital skills diffusion in fostering the architecture, engineering and construction (AEC) industry has been highlighted for more than a decade. The extent to which this objective can be achieved depends on several factors. An augmented building information modelling (BIM) adoption stems from, but is not restricted to, government policies and initiatives. This study aims to assess the diffusion of digital skills, specifically through BIM adoption and to establish feasible strategies for such adoption within the Italian AEC industry,= taking into account institutional, organisational and project-related factors. This purpose is achieved through an initial investigation of the most significant hurdles in BIM uptake and various BIM-promoting policies adopted at an international level. Moreover, a rigorous review of recent developments in the diffusion of innovation theory is presented. Based on findings and combining the experiences of various authors in BIM-related research an exploratory online survey was conducted, resulting in identification of the clients' lack of knowledge as the most critical challenge to BIM adoption in the Italian AEC industry. Following this finding, the study suggests five strategies to leverage BIM benefits to their full extent, to increase the perception of BIM benefits and to bridge the current gap between the industry and academia

Dharmagupta's unfinished translation of the Diamond-cleaver (Vajracchedika-Prajnaparamita-sutra)

Albermani, F ORCiD: 0000-0001-8540-1724Experimental and finite element results for buckle interaction in subsea pipelines are presented in this paper. Experimental results for buckle propagation and pure bending of pipes are presented first followed by buckle interaction results. A finite element model, verified against the experimental results, is used to develop buckle interaction envelopes. The analysis is conducted using both transient and steady state conditions. The results highlight the vulnerability of subsea pipelines to buckle interaction particularly in deep waters

L'utopie aux Etats Unis au 20è siécle

The essay describes the presence and types of literary utopias in 20th century America

Propagation buckling in deep sub-sea pipelines

Albermani, F ORCiD: 0000-0001-8540-1724The paper investigates buckle propagation in deep sub-sea pipelines. Experimental results are presented using ring squash tests and hyperbaric chamber tests, and are compared with a modified analytical solution and with numerical results using finite element analysis. The experimental investigation was conducted using commercial aluminium pipes with diameter-to-thickness (D/t) ratio in the range 20–48. In contrast to conventional cylindrical pipe, a faceted cylindrical geometry is also investigated. Preliminary analysis of a faceted pipe shows that a substantial increase in buckling capacity can be achieved for the same D/t ratio.Associated Grant:CSIRO Flagship Collaboration Fun

Buckle interaction in textured deep subsea pipelines

The paper presents numerical results of lateral buckling, buckle propagation and buckle interaction in textured subsea pipelines, and compares these results to those in conventional cylindrical pipelines. Transient and steady states are used to investigate the interaction between lateral and propagation buckling, and interaction envelopes are presented for textured and cylindrical pipes. It is shown that the textured pipe offers a superior buckle propagation response that is relatively insensitive to imperfection. The interaction between lateral and propagation buckling in cylindrical and textured pipes makes a substantial reduction in buckle initiation pressure, particularly at lower D/t ratios

Interaction between lateral buckling and propagation buckling in textured deep subsea pipelines

Albermani, F ORCiD: 0000-0001-8540-1724Novel analytical solution to lateral buckling of pipelines based on localization of buckle patterns is proposed. Finite element study is conducted on lateral buckling of a full length pipe. Analytical and FE results are compared and advantages of analytical solution to FE model are highlighted. Interaction between lateral buckling and propagation buckling of cylindrical pipe and textured pipe under transient load path are investigated

Interaction between upheaval/lateral and propagation buckling in subsea pipelines

Due to high service temperatures and internal pressures in oil and gas pipelines, axial compression forces are induced in the pipe due to seabed friction. Slender trenched pipelines can experience global buckling in the vertical plane (upheaval buckling) while untrenched pipelines buckle in the horizontal plane (lateral buckling). Furthermore, deep subsea pipelines subjected to high external hydrostatics pressures can undergo catastrophic propagation buckling. In this study, the possible interaction between upheaval/lateral buckling and propagation buckling is numerically investigated using finite element analysis. A new concept is proposed for subsea pipelines design that gives higher capacity than conventional pipelines

Buckle interaction in deep subsea pipelines

The paper investigates the interaction between propagation buckling and lateral buckling in deep subsea pipelines. Lateral buckling is a possible global buckling mode in long pipelines while the propagation buckling is a local mode that can quickly propagate and damage a long segment of a pipeline in deep water. A numerical study is conducted to simulate buckle interaction in deep subsea pipelines. The interaction produces a significant reduction in the buckle design capacity of the pipeline. This is further exasperated due to the inherent imperfection sensitivity of the problem