Search Results (33)

The city of Al Ain is a fast-developing area. With building typology varying from low-rise to mid-rise, sustainable design in buildings is needed. As the majority of the city’s population is Emirati Citizens, the percentage of expats is increasing. The expats tend to live in mid-rise buildings. One of the central midrise areas is AL Ain Square. This study aims to investigate how an optimized mashrabiya pattern can impact the energy and the Predicted Mean Vote (PMV) in a 3-bedroom apartment, fully oriented to the south, of an expat family. The methodology is as follows: case study selection, Weather analysis, Modeling/Validation of the base case scenario, Optimization of the mashrabiya pattern, Simulation of various scenarios, and Results. Analyzing the selected case study is the initial step of the methodology. This analysis begins with the district, building typology, and the chosen apartment. The weather analysis is relevant for using the mashrabiya (screen device) and the need to improve energy consumption and thermal comfort. The modeling of the base case shall be performed in Rhino Grasshopper. The validation is based on a one-year electricity bill provided by the owner. The optimization of mashrabiya patterns is an innovative process, where various designs are compared and then optimized to select the most efficient pattern. The solutions to the selected scenarios will then yield the results of the optimal scenario. This study is relevant to industry, academia, and local authorities as an innovative approach to retrofitting buildings. Additionally, the research presents a creative vision that suggests optimized mashrabiya patterns can significantly enhance energy savings, with the hexagonal grid configuration demonstrating the highest efficiency. This finding highlights the potential for geometry-driven shading optimization tailored to specific climatic and building conditions. Contrasting earlier mashrabiya studies that assess one static pattern, we couple a geometry-agnostic evolutionary solver with a utility-calibrated EnergyPlus model to test thousands of square, hexagonal, and triangular permutations. This workflow uncovers a previously undocumented non-linear depth perforation interaction. It validates a hexagonal screen that reduces annual cooling energy by 12.3%, establishing a replicable, grid-specific retrofit method for hot-arid apartments. Full article

The growing application of carbon fiber-reinforced polymers (CFRPs) in construction opens new possibilities for replacing traditional materials such as steel, particularly in strengthening and retrofitting concrete structures. CFRP materials offer notable advantages, including high tensile strength, low self-weight, corrosion resistance, and the ability to be tailored to complex geometries. This paper provides a comprehensive review of current technologies used to strengthen concrete columns, with a particular focus on the application of fiber-reinforced polymer (FRP) tubes in composite column systems. The manufacturing processes of FRP composites are discussed, emphasizing the influence of resin types and fabrication methods on the mechanical properties and durability of composite elements. This review also analyzes how factors such as fiber type, orientation, thickness, and application method affect the load-bearing capacity of both newly constructed and retrofitted damaged concrete elements. Furthermore, the paper identifies research gaps concerning the use of perforated CFRP tubes as internal reinforcement components. Considering the increasing interest in innovative column strengthening methods, this paper highlights future research directions, particularly the application of perforated CFRP tubes combined with external composite strengthening and self-compacting concrete (SCC). Full article

Atrial leadless pacemakers (ALPMs) offer a minimally invasive solution for patients requiring atrial pacing, but current designs face significant challenges related to fixation stability, perforation risk, and retrievability. This study presents a novel self-expanding nitinol fixation system designed for deployment within the left atrial appendage (LAA), incorporating a flexible adapter for secure pacemaker engagement and retrieval. Finite-element simulations were conducted to assess gravitational displacement across different anatomical orientations, and fixture-expansion behavior was analyzed under various mesh configurations. The pacemaker drop analysis results demonstrated minimal displacement in neutral and upward-tilted LAA models, with increased instability observed in downward-tilted orientations. The fixture-expansion study showed that the 0.2 mm mesh design provided adequate mechanical strength and strain tolerance while maintaining a compact profile. This novel fixation system improves current ALPM limitations by providing stable, retrievable anchoring and favorable biomechanical performance. It may also serve as a dual-function platform for atrial pacing and stroke prevention when integrated with a left atrial appendage (LAA) occluder. These findings support further preclinical validation for clinical translation. Full article

Background: Colonic obstructions present a serious medical emergency that requires prompt surgical intervention to prevent life-threatening complications. Cecostomy, a procedure involving the creation of an opening in the cecum to decompress the colon, serves as one surgical approach for managing these obstructions. The aim of this review is to evaluate the effectiveness and benefits of cecostomies in emergency surgical settings, with a focus on recent clinical studies and case reports. Cecostomy is highlighted as a bridge procedure in cases such as obstructive carcinomas, providing data on success rates, relative survival, and clinical effectiveness. The importance of the patient’s condition and surgeon expertise in selecting cecostomy as a procedure is emphasized. Further comparative research is suggested to optimize the selection criteria, providing a strong, clinically oriented conclusion. Methods: A comprehensive literature review was conducted to identify studies and case reports focusing on the application of cecostomies in cases of acute colonic obstruction. Articles were selected based on their relevance to emergency surgery, the effectiveness of cecostomies, and patient outcomes in various clinical scenarios, including obstructive carcinomas and colonic pseudo-obstructions. Results: The analysis reveals that cecostomies provide rapid decompression and effective relief from colonic obstruction, particularly when immediate intervention is needed to prevent bowel perforation or ischemia. In several cases, cecostomies act as a bridge to more definitive surgical treatments, such as resection and anastomosis, and are associated with reduced morbidity and mortality. The selection of cecostomy as a preferred procedure depends on the patient’s condition, location of the obstruction, and surgeon expertise. Conclusions: Cecostomies play a crucial role in the emergency management of colonic obstructions, offering a viable and sometimes lifesaving alternative for rapid decompression. Understanding the indications and appropriate use of cecostomies can enhance patient outcomes and provide surgeons with effective strategies for managing acute colonic obstructions. Further research is warranted to refine selection criteria and to compare outcomes between cecostomies and other decompressive techniques in emergency settings. Full article

The failure of 3D-printed Polylactide (PLA) specimens with circular holes was studied under tensile and cyclic loading, respectively, by an inserted pin. Experiments were conducted for the perforated PLA specimens with various print angles from 0° to 90°, as well as [0°/90°]s and [0°/±45°/90°]s. The hole locations varied along the specimens. The PLA specimens showed two different failure modes: one through the print lines and the other between the print lines. Different print angles resulted in different tensile failure stresses under pin loading. The cyclic tests of different print angles showed very similar S-N data as the applied stresses were normalized to their tensile failure stresses if the failure mode was through the print lines. On the other hand, cyclic failure between print lines showed distinctly separated S-N data, even with the normalized applied stresses. The tensile failure stresses, failure locations, and orientations were successfully predicted using the failure criterion that is based on both stress and stress gradient conditions. A proposed mathematical interpolation equation provided good estimations of the tensile failure stresses and S-N curves of specimens with different print angles once the failure stresses were known for the 0° to 90° specimens. Full article

The main method used to exploit unconventional oil and gas reservoirs involves multi-cluster perforation combined with hydraulic fracturing in horizontal wells. However, as the use of this technology has expanded, challenges like reduced perforation efficiency and elevated fracture initiation pressure have surfaced. The depth-controlled oriented perforation technique helps achieve uniform fracture initiation, enhance efficiency, and lower initiation pressure. In this study, a hydraulic fracturing fluid–solid coupling model at the perforation scale was established using the 3D lattice method to compare the near-wellbore fracture morphologies of depth-controlled oriented perforation, spiral perforation, and oriented perforation. Additionally, this study analyzes the effects of injection rate, reservoir elastic modulus, and horizontal stress difference on the fracture morphology and initiation pressure of depth-controlled oriented perforation. This study clarifies the applicability of depth-controlled oriented perforation in different types of reservoirs for the first time. The results indicate that intermediate fractures between spiral and oriented perforations are hindered, while depth-controlled oriented perforation ensures uniform fracture initiation. In the injection rate range of 0.144 to 0.360 L/min, an increase in injection rate accelerates the rise of fluid pressure within the perforations, leading to an increase in fracture initiation pressure. Therefore, excessively high injection rates are unfavorable for fracture initiation. Through depth-controlled oriented perforation, long and singular fractures can be formed in reservoirs with significant horizontal stress differences and high elastic moduli. Full article

In 1944, the architect Antonio Gómez Davó designed and built a new house for Mr. Ferrer at Rocafort in the suburbs of Valencia (Spain). In this same year, Europe, America, Russia and even Japan were still at war and Spain was recovering from its own intestine conflict. Therefore, architectural innovations and influences were scarce, as was the circulation of specialized journals on the matter. Still, many creations were occurring, like ceramic vaults and the brise-soleil; further, the architect Le Corbusier had stated his profound nostalgia for the Mediterranean, a sea that he had come to appreciate in his travels to the “East”. In the case of Gómez Davó, having been born and raised in a prominent family of Valencia, he could not remain indifferent to the design features that appeared in the vernacular architecture of the area, especially the type of inclined louvers of Arabic descent, that covered bow-windows and balconies and which have come to be known in Spain as the Majorcan louvers; these are currently even employed by prominent architects like Rafael Moneo at the extension of the Painter Miro Foundation. However, with so many difficult circumstances surrounding him, Gómez Davó could not get to the point of producing a ground-breaking design based on solar assumptions for the whole façade of the house he was building; instead, when providing an entrance porch apt for living life in the pure Mediterranean tradition, he ventured to construct a surprising perforated wall oriented to the south in order to control radiation in the winter and provide shade in the summer while affording excellent light and superb conditions of ventilation. By means of self-devised simulation tools, we have analyzed the conditions of the house and especially of his innovative brise-soleil, which are at times reminiscent of Alvar Aalto’s solutions for day-lit roofs, and which he intuitively adapted to the latitude of Valencia with the help of incipient notions of solar geometry. By outlining such unknown and bold precedent and assessing the house’s proper climatic performance, we contribute to revitalizing the early and daring pioneers of solar architecture in peripheral Spain and Europe during the birth of critic regionalism, a fact often disregarded in the conventional history of Modern Architecture. Full article

Effective sound absorption is crucial in environments like schools and hospitals. This study evaluates open-pore polyurethane foam and perforated onyx panels, which attenuate noise via distinct mechanisms: porous materials convert sound energy to heat through viscous and thermal losses, while perforated panels use resonant behaviour for energy dissipation. The impact of hole geometries and panel orientations on the sound absorption coefficient and noise reduction coefficient was investigated using COMSOL Multiphysics 6.0 for finite element analysis and ISO 10534-2 compliant impedance tube experiments. Six perforated panel configurations were 3D-printed with varying hole diameters and backed by a 24 mm polyurethane foam layer. Both ‘forward’ and ‘reverse’ configurations were assessed. A tapered hole from 4 mm to 2 mm showed the highest sound absorption across the 100–4000 Hz range, with a noise reduction coefficient of 0.444, excelling in both orientations. Reverse designs generally performed less, underscoring the importance of hole geometry and orientation. Experimental results aligned with FEA simulations, validating the computational model. This study elucidates sound absorption mechanisms of porous and perforated materials, providing a validated framework for material selection in noise-sensitive settings and highlighting 3D-printing’s potential in noise control. Full article

In the field of CO₂ capture and sequestration, ensuring the safety of pipeline infrastructure is paramount to successful climate change mitigation efforts. This study investigates the dynamics of CO₂ dispersion from pipeline systems, assessing not only the transport process but also the physical properties and associated hazards. Advanced simulation techniques are used to model how different states of CO₂ (gas, liquid, and supercritical) and varying pipeline characteristics—such as perforation sizes, flow rates, and orientations—affect the dispersion patterns in the event of a leak. Simulations cover a range of atmospheric conditions, emphasizing the role of atmospheric stability and wind speed in shaping dispersion and defining potential impact zones. An analysis of historical pipeline accidents is included to inform risk management strategies. The results show that the orientation of the pipeline has a significant effect on dispersion, with downward leaks causing the largest impact zones, particularly under supercritical conditions. The results highlight the need for adaptive safety strategies that take into account real-time CO₂ transport conditions and localized environmental data. By integrating these factors, the study recommends refining safety protocols and emergency response strategies to improve pipeline resilience and public safety against potential leaks. Key findings include the quantification of the relationship between leak parameters and dispersion areas, providing a valuable framework for future safety improvements. Full article

This study examines the common raven (Corvus corax) population on Lanzarote, Spain, at a previously unstudied site. The study aimed to compare the use of camera trap technology and human observation in capturing a wide repertoire of raven behaviour and pay close attention to the perforation of aluminium cans, a behaviour that has not been described in the scientific literature previously but has been reported anecdotally through human observation. Five cameras were sited over a period of 6 months, with three aluminium cans placed at each location. One of the three cans was baited with meat and eggs, mimicking wild feeding substrate. Human observations took place over the same period of time in the same locations. Raven sightings were highly correlated in human-inhabited areas as well as agricultural areas, seemingly linked to food acquisition. Camera trap technology identified a greater number of can-orientated behaviours (interaction, manipulation, peeking inside, and pecking) compared to the human observation method. Conversely, human observation yielded a greater number of non-can-orientated behaviours (analysed as a group) when compared to that of camera trap observation. Overall, there was a significantly greater number of ravens observed via human observation when compared to that of camera trap observation. Initial evidence suggests that ravens only perforate cans they deem salient in terms of food acquisition, with beer cans being the most common focus of the behaviours observed, possibly linked to olfactory stimuli, the movement of the can or learned behaviour relating to reward acquisition. This study presents new data regarding object interaction in ravens, adding to the current body of knowledge. Full article

The economic exploitation of unconventional gas and oil in deep shale relies closely on effective hydraulic fracturing stimulations. However, the fracturing operations of deep shale reservoirs face challenges of insufficient fracture growth and a rapid decline in productivity due to the increasing in situ stress level. In addition, the shale strata on the margin of the Sichuan Basin are frequently folded and faulted, and the change in bedding inclinations significantly complicates the process of hydraulic fracturing. The investigation of the combined effect of the in situ stress level and bedding anisotropy on the hydraulic fracture configuration is vital for fracturing engineering design. To analyze this, we conducted hydraulic fracturing tests on shale cores to simulate the hydraulic fracture initiation and growth from a horizontally positioned perforation. By using acoustic emission detection and CT scans, the influence of natural stress levels and the angle of the shale’s bedding on the process of hydraulic fracturing in shale and the resulting fracture geometry were analyzed. The results showed that the area of hydraulic fracture under a higher stress level (σ₁ = 50 MPa, σ₃ = 40 MPa) was about 13%~23% smaller than that created under the lower stress level (σ₁ = 30 MPa, σ₃ = 20 MPa) when the bedding angle was smaller than 60°. With the increase in bedding angle, the curves of the fracture area and fracture network index under two different stress levels presented similar decreasing trends. Also, the time from micro-crack generation to sample breakdown was significantly reduced when the bedding orientation changed from the horizontal to vertical position. The increasing stress level significantly increased the breakdown pressure. In particular, the fracturing of shale samples with bedding angles of 0° and 30° required a higher fluid pressure and released more energy than samples with larger bedding inclinations. Additionally, the measurement of the sample radial deformation indicated that the hydraulic fracture opening extent was reduced by about 46%~81% with the increasing stress level. Full article

Intraoperative OCT is an innovative and promising technology which allows anterior and posterior segment ocular surgeons to obtain a near-histologic cross-sectional and tomographic image of the tissues. Intraoperative OCT has several applications in ocular surgery which are particularly interesting in the context of corneal transplantation. Indeed, iOCT images provide a direct and meticulous visualization of the anatomy, which could guide surgical decisions. In particular, during both big-bubble and manual DALK, the visualization of the relationship between the corneal layers and instruments allows the surgeon to obtain a more desirable depth of the trephination, thus achieving more type 1 bubbles, better regularity of the plane, and a reduced risk of DM perforation. During EK procedures, iOCT supplies information about proper descemetorhexis, graft orientation, and interface quality in order to optimize the postoperative adhesion and reduce the need for re-bubbling. Finally, mushroom PK, a challenging technique for many surgeons, can be aided through the use of iOCT since it guides the correct apposition of the lamellae and their centration. The technology of iOCT is still evolving: a larger field of view could allow for the visualization of all surgical fields, and automated tracking and iOCT autofocusing guarantee the continued centration of the image. Full article

This paper presents a study on the dynamic behavior of thin aluminum plates subjected to consecutive fragment impact and blast loading. To this end, two separate experimental setups are used. In the first setup, 2 mm thick aluminum plates $EN$-$AW$-$1050A$-$H24$ were subjected to the ballistic impact of fragment-simulating projectiles (FSPs). Experiments were carried out for FSP calibers of 7.62 mm and 12.7 mm considering both single impact and triple impacts with variations in the spacing of the impact locations. The out-of-plane displacement and in-plane strain fields were measured using digital image correlation (DIC) coupled to a pair of high-speed cameras in a stereoscopic setup. In the second setup, a subsequent blast loading was applied to the perforated plates using an explosive-driven shock tube (EDST). After the plates are perforated, the strain field around the holes depended on the caliber, the impact orientation of the FSP, and the distance between the impact locations. When the blast loading was applied, cracks tended to appear in areas of strain concentration between the perforated holes. It was found that the relative distance between the holes significantly influences the target’s response mode. Full article

There are many technologies to implement sand control in sand-prone wells, drilled in either weakly or nonconsolidated sandstones. Technologies that are used to prevent sanding can be divided into the following groups: screens (wire-wrapped screens, slotted liners, premium screens, and mesh screens), gravel packs, chemical consolidation, and technological ways (oriented perforation and bottomhole pressure limitation) of sanding prevention. Each particular technology in these groups has their own design and construction features. Today, slotted liners are the most well-studied technology in terms of design, however, this type of sand control screen is not always accessible, and some companies tend towards using wire-wrapped screens over slotted liners. This paper aims to study the design criteria of wire-wrapped screens and provides new data regarding the way in which wire design affects the sanding process. Wires with triangular (wedge), trapezoidal, and drop-shaped profiles were tested using prepack sand retention test methodology to measure the possible impact of wire profile on sand retention capabilities and other parameters of the sand control screen. It was concluded that a trapezoidal profile of wire has shown the best result both in terms of sand production (small amount of suspended particles in the effluent) and in particle size distribution in the effluent, that is, they are the smallest compared to other wire profiles. As for retained permeability, in the current series of experiments, high sand retention did not affect retained permeability, although it can be speculated that this is mostly due to the relatively high particle size distribution of the reservoir. Full article

The present paper explores a new concept of a hybrid eco-composite by substituting the natural fibre plies with thin wood veneers. The new composite, named Fibre–Wood Laminate (FWL), is inspired by fibre–metal laminate materials. The studied FWL configuration consisted of a single thin pinewood veneer at each of the outer layers of a flax woven fabric reinforced bio-epoxy composite manufactured by infusion. Three-point bending results showed that wood veneer gives a highly anisotropic nature to the FWL. In the best case, with the grain of the wood at 0°, the stiffness and the strength increased by 28 and 41%, respectively, but reduced the strain-at-break by 27% compared to the flax fibre reinforced bio-epoxy (FFRB). The penetration and perforation energy thresholds and the peak force of the FWL obtained by falling weight impact tests were 32, 29, and 31% lower than those of the FFRB, respectively. This weakening was due to using single wood veneers, so the challenge for improving impact properties will be to explore thicker FWLs with different stacking sequences and orientations. The effect of immersing the FWL in seawater also showed considerable differences. The epoxy matrix filled the cellular structure of the wood veneers, creating a barrier effect and reducing the amount of water absorbed by the flax fibres. Full article