Search Results (931)

In this research project a large linear electromagnetic actuator (LLEA) was designed and manufactured. The electromagnetic performance was published in previous works, but in this paper we focus on the technological challenges related to the manufacturing in particular. This LLEA was based on the magnet-free switched-reluctance principle, having six effective energised stator “teeth” and four passive mover parts (4:6 ratio). Various aspects and challenges encountered during the manufacturing, transport, and assembly are discussed. Thermal expansion of steel contributed to the decision of the modular design, with each module having 1.3 m in length, with a 2 mm longitudinal dilatation gap. The initial prototype was tested with a 10.6 m length, with plans to extend the test track to 60 m, which was fully achievable due to the modular design and required 29 tons of electrical steel to be built. The stator laminations were cut by a bespoke progressive tool with stamping, and other parts by a CO₂ laser. Mounting was based on welding (back of the stator) and clamping plates (through insulated bolts). The linear longitudinal force was on the order of 8 kN, with the main air gap of 7.5–10 mm on either side of the mover. The lateral forces could exceed 40 kN and were supported by appropriate construction steel members bolted to the concrete floor. The overall mechanical tolerances after installation remained below 0.5 mm. The technology used for constructing this prototype demonstrated the cost-effective way for a semi-industrial manufacturing scale. Full article

The superb dynamic performance of steel-plate composite (SC) structures under unexpected impact loading depends on the good design of the connection between the SC wall and foundation. This study investigated the flexural behavior and dynamic responses of SC wall-to-foundation connections subjected to low-velocity impact. Impact tests were performed on three SC connection specimens to evaluate failure mode, impact force, deflection, and strain responses. The effects of concrete strength grade and impact energy were analyzed in detail. All specimens exhibited flexural failure, with three distinct stages observed during impact. The experimental results demonstrated that compared to the specimen with C30 concrete, the specimen with C50 concrete significantly reduced wall damage, decreased deflections, and enhanced deflection recovery ability. It can be concluded that increasing the concrete strength grade effectively improves the impact resistance of SC wall-to-foundation connections. In addition, peak impact force, global deflection response, residual strains, and interface crack length were highly sensitive to changes in impact energy, whereas deflection recovery exhibited lower sensitivity. Furthermore, a finite element model was developed and validated against experimental results. Parametric studies explored the influence of key parameters with expanded ranges on the impact responses of SC wall-to-foundation connections. Full article

Crack damage can significantly reduce the ultimate strength of marine structures, potentially leading to progressive collapse. This study employs finite element analysis to investigate how cracks affect the strength of plates and stiffened panels under uniaxial and biaxial compression, providing insights essential for robust structural design. The effects of crack size and orientation are explored through a systematic evaluation of longitudinal, transverse, and bidirectional cracks—sized at 10%, 25%, and 50% of structural dimensions (plate length and plate breadth/web height)—in both plates and unstiffened panels. The analysis identifies key parameters governing strength degradation and reveals that stiffened panels are more resistant to cracking, whereas plates are more sensitive to crack orientation and loading direction. These findings underscore the role of crack characteristics and structural reinforcement in maintaining residual strength and provide guidance for improving the accuracy and reliability of ultimate strength predictions. Full article

Zebrafish are model organisms for drug screening owing to their transparent bodies, rapid embryonic development, and genetic similarities with humans. However, using standard polystyrene culture plates can limit the oxygen supply, potentially affecting embryo survival and the reliability of assays conducted in zebrafish. In this study, we evaluated the application of a novel, highly oxygen-permeable culture plate (InnoCell^TM) in zebrafish development and drug screening assays. Under both normal and oxygen-restricted conditions, zebrafish embryos cultured on InnoCell^TM plates exhibited significantly improved developmental parameters, including heart rate and body length, compared with those cultured on conventional polystyrene plates. The InnoCell^TM plate enabled a significant reduction in medium volume without compromising zebrafish embryo viability, thereby demonstrating its advantages, particularly in high-throughput 384-well formats. Drug screening tests using antiangiogenic receptor tyrosine kinase inhibitors (TKIs) revealed enhanced sensitivity and more pronounced biological effects in InnoCell^TM plates, as evidenced by the quantification of intersegmental blood vessels and gene expression analysis of the vascular endothelial growth factor receptor (vegfr, also known as kdrl). These results indicate that the InnoCell^TM highly oxygen-permeable plate markedly improves zebrafish-based drug screening efficiency and assay reliability, highlighting its potential for widespread application in biomedical research. Full article

Background: Current methods of postural control assessments and interventions to improve postural stability and thereby prevent falls often fail to incorporate the hazardous perturbation situations that frequently accompany falls. Virtual environments can safely incorporate these hazards. The purpose of the study was to identify if virtual slip and trip perturbations can be used as an exposure paradigm in place of real slip and trip perturbations to improve postural control. Methods: Fifteen healthy young adults were included in this study. Two paradigms, real gait exposure (real) and virtual environment gait exposure (virtual), consisting of real and virtual slip and trip trials, were performed by each participant in a counterbalanced order to avoid order effects. At baseline and following real and virtual paradigms, the modified clinical test for sensory integration and balance (mCTSIB), limits of stability (LOS), and single-leg stance (SLS) using BTracks balance plate were administered. Separate one-way (baseline vs. Real vs. Virtual) repeated measures analysis of variance were conducted on response variables. Results: In the posterior left quadrant of the LOS, significant differences were found after the real paradigm compared to baseline (p = 0.04). For the anterior left quadrant and total LOS, significant differences post real paradigm (p = 0.002 and p < 0.001) and virtual paradigm (p = 0.007 and p < 0.001) compared to baseline were observed. For the SLS, the left-leg significant differences were observed post real paradigm (p = 0.019) and virtual paradigm (p = 0.009) compared to BL in path length, while significant main effects were found for mean sway velocity for the left leg only (p = 0.004). For the right leg, significant differences were only observed after the virtual paradigm (p = 0.01) compared to BL. Conclusions: Both virtual and real paradigms were identified to improve postural control. The virtual paradigm led to increased postural control in the right-leg SLS condition, while the real paradigm did not, without any adverse effects. Findings suggest virtual reality perturbation exposure acutely improves postural control ability compared to baseline among healthy young adults. Full article

Stylolites are a common mineral dissolution feature in rocks that develop during compression and form distinct tooth structures. On a tectonic plate scale, mid-ocean ridges (MORs) and transform faults are a significant feature of the Earth’s surface that develop due to accretion of new material in an extensional regime. We present a comparison between the two features and argue that transform faults in MOR are similar to the sides of stylolite teeth, with both features representing kinematic faults (KFs). First, we present a numerical model of both stylolite and MOR growth and show that in both cases, KFs nucleate and grow spontaneously. In addition, we use a well-established technique (Family–Vicsek scaling) of describing fractal self-affine interfaces, which has been used for stylolites, to characterize the pattern of MOR systems in both simulations and natural examples. Our results show that stylolites and MOR have self-affine scaling characteristics with similar scaling regimes. They both show a larger roughness exponent at the small scale, a smaller exponent at the intermediate scale, followed by a flattening of the system at the largest scale. For stylolites, the physical forces behind the scaling are the surface energy at the small mineral scale, the elastic energy at the intermediate scale, followed by the system reaching the correlation length where growth stops. For MORs, the physical forces behind the scaling are not yet clear; however, the self-affine scaling shows that transform faults at MORs do not have a preferred spacing, but that the spacing is fractal. Our study offers a new perspective on the study of natural roughening phenomena on various scales, from minerals to tectonic plates, and a new view on the development of MORs. Full article

Linear passive electrical devices/components are usually characterized in the frequency domain by their impedance, i.e., the ratio of the voltage and current phasors. The use of the impedance concept does not raise particular concerns in low-frequency regimes; however, things become more complicated when it comes to rapid time-varying phenomena, mainly because the voltage depends not only on the position of the points between which it is defined but also on the choice of the integration path that connects them. In this article, based on first principles (Maxwell equations and Poynting vector flow considerations), we discuss the concept of impedance and define it unequivocally for a class of electrical devices/components with rotational symmetry. Two application examples are presented and discussed. One simple example concerns the per-unit-length impedance of a homogeneous cylindrical wire subject to the skin effect. The other, which is more elaborate, concerns a heterogeneous structure that consists of a dielectric disk sandwiched between two metal plates. For the lossless situation, the high-frequency impedance of this device (circular parallel plate capacitor) reaches zero when the frequency reaches a certain critical frequency f_c; then, it becomes inductive and increases enormously when the frequency reaches another critical frequency at 1.6 f_c. The influence of losses on the impedance of the device is thoroughly investigated and evaluated. Impedance corrections due to dielectric losses are analyzed using a frequency-dependent Debye permittivity model. The impedance corrections due to plate losses are analyzed by considering radial current distributions on the outer and inner surfaces of the plates, the latter exhibiting significant variations near the critical frequencies of the device. Full article

Study design: The advent of the Matrix Wave^TM System (Depuy-Synthes)—a bone-anchored Mandibulo-Maxillary Fixation (MMF) System—merits closer consideration because of its peculiarities. Objective: This study alludes to two preliminary stages in the evolution of the Matrix Wave^TM MMF System and details its technical and functional features. Results: The Matrix Wave^TM System (MWS) is characterized by a smoothed square-shaped Titanium rod profile with a flexible undulating geometry distinct from the flat plate framework in Erich arch bars. Single MWS segments are Omega-shaped and carry a tie-up cleat for interarch linkage to the opposite jaw. The ends at the throughs of each MWS segment are equipped with threaded screw holes to receive locking screws for attachment to underlying mandibular or maxillary bone. An MWS can be partitioned into segments of various length from single Omega-shaped elements over incremental chains of interconnected units up to a horseshoe-shaped bracing of the dental arches. The sinus wave design of each segment allows for stretch, compression and torque movements. So, the entire MWS device can conform to distinctive spatial anatomic relationships. Displaced fragments can be reduced by in-situ-bending of the screw-fixated MWS/Omega segments to obtain accurate realignment of the jaw fragments for the best possible occlusion. Conclusion: The Matrix Wave^TM MMF System is an easy-to-apply modular MMF system that can be assembled according to individual demands. Its versatility allows to address most facial fracture scenarios in adults. The option of “omnidirectional” in-situ-bending provides a distinctive feature not found in alternate MMF solutions. Full article

Air purification is a key process aimed at removing harmful impurities and providing a safe and comfortable environment for human life and work. This study presents the results of an investigation into the composition, textural, and sorption properties of a multichannel carbon filtering material developed for air purification from biological (infectious) contaminants. The filtering block has a cylindrical shape and is manufactured by extrusion of a plastic composition based on carbonized rice husk with the addition of binding agents, followed by staged thermal treatment (calcination, activation, and demineralization). The filter’s effectiveness is based on the inactivation of pathogenic microorganisms as the air passes through the porous surface of the sorbent, which is modified with broad-spectrum antiseptic agents (active against bacteria, bacilli, fungi, and protozoa). X-ray diffraction analysis revealed the presence of amorphous carbon in a tubostratic structure, with a predominance of sp- and sp²-hybridized carbon atoms not incorporated into regular graphene lattices. IR spectroscopy demonstrated the presence of reactive functional groups characteristic of the developed porous structure of the material, which is capable of selective sorption of antiseptic molecules. SEM surface analysis revealed an amorphous texture with a loose structure and elements in the form of spherical semi-ring formations formed by overlapping carbon plates. An experimental setup was also developed using cylindrical multichannel carbon blocks with a diameter of 48 mm, a length of 120 mm, and 100–120 longitudinal channels with a cross-section of 1 mm². The obtained results confirm the potential of the proposed material for use in air purification and disinfection systems under conditions of elevated biological risk. Full article

The electroosmotic flow (EOF) of non-Newtonian fluids plays a significant role in microfluidic systems. The EOF of Powell–Eyring fluid within a parallel-plate microchannel, under the influence of both electric field and pressure gradient, is investigated. Navier’s boundary condition is adopted. The velocity distribution’s approximate solution is derived via the homotopy perturbation technique (HPM). Optimized initial guesses enable accurate second-order approximations, dramatically lowering computational complexity. The numerical solution is acquired via the modified spectral local linearization method (SLLM), exhibiting both high accuracy and computational efficiency. Visualizations reveal how the pressure gradient/electric field, the electric double layer (EDL) width, and slip length affect velocity. The ratio of pressure gradient to electric field exhibits a nonlinear modulating effect on the velocity. The EDL is a nanoscale charge layer at solid–liquid interfaces. A thinner EDL thickness diminishes the slip flow phenomenon. The shear-thinning characteristics of the Powell–Eyring fluid are particularly pronounced in the central region under high pressure gradients and in the boundary layer region when wall slip is present. These findings establish a theoretical base for the development of microfluidic devices and the improvement of pharmaceutical carrier strategies. Full article

The aim of this work is to present an original, relatively simple, and elegant approach to the analysis of long rectangular plates subjected to uniformly distributed vertical loads acting on various surfaces. Plate analysis is important in many fields, especially where components are either rectangular plates or can be approximated as such. The Transfer Matrix Method is increasingly used in research, as evidenced by the references cited. The advantages of this method lie in the simplicity of its algorithm, the ease of implementation in programming, and its straightforward integration into optimization software. The approach consists of discretizing the rectangular plate by sectioning it with planes parallel to the short sides—i.e., perpendicular to the two long edges. This results in a set of beams, each with a length equal to the width of the plate, a height equal to the plate’s thickness, and a unit width. Each unit beam has support at its ends that replicate the edge conditions of the plate along its long sides. In the study presented, the rectangular plate is embedded along its two long edges, meaning the unit beam is considered embedded at both ends. The Transfer Matrix Method is particularly valuable because it lends itself well to iterative calculations, making it easy to develop software capable of analyzing long rectangular plates quickly. This makes it especially useful for shape optimization applications, which we intend and hope to pursue in future studies. Full article

The role of weirs in flow regulation in water resources infrastructure and flood control is well known. In the meantime, the study of full-width plate weirs (FWPW), due to their wide application and lacking findings, is of great importance. In this study, experimental models were conducted at Babol Noshirvani University of Technology to investigate flow passing through FWPWs with five different heights (p = 0.07, 0.09, 0.11, and 0.15 m) under eight discharge conditions (Q = 1.4 to 6.3 L/s). The experiments were carried out in a flume measuring 4 m in length, 0.6 m in width, and 0.2 m in height. The discharges were measured with a calibrated flowmeter, and the water depths upstream of the weir (h) and the tailwater depths (h₁) were measured with a point gauge with an accuracy of 0.1 mm. For each test, the discharge coefficient (C_d), relative residual energy (E₁/E₀), and relative energy dissipation ((E₀ − E₁)/E₀) were computed. The proposed equation for calculating discharge achieved good accuracy with RMSE = 0.0002, MAE=0.0002, and R² = 0.997. Results show a reducing trend of C_d by increasing h/P, which is compatible with previous results. It was observed that at a constant discharge, relative residual energy reduces by an average of 47% by increasing weir height, and at a constant P, increasing flow discharge increases it a little. A novel accurate equation for relative energy dissipation in FWPW was proposed based on h/P that provided specific constant coefficients for each p value. Full article

Background/Objectives: Distal forearm fractures are the most common fractures in children. Three surgical techniques are most commonly used at the level of the radial diametaphysis on the distal forearm in children: K-wire, ascending ESIN (elastic stable intramedullary nail) or plate osteosynthesis. The aim of this study was to compare these procedures in children with distal diametaphyseal radius fractures regarding operative and functional outcome. Methods: A retrospective study was conducted in two level 1 trauma centers. Children and adolescents aged 2 to 15 years were included. The study period was from January 2010 to December 2022. The hospital information system was used to record patient age, gender, height, weight, fracture location, degree of angular deformity postoperatively, surgical procedure and postoperative complications, which were described in the medical records of the hospital information system. Complications graded by modified Clavien–Dindo–Sink served as the primary outcome. Reduction accuracy, operative and fluoroscopy times, immobilization length and postoperative motion were the secondary endpoints. Results: A total of 213 children were included in the study. K-wire osteosynthesis was performed in 25%, nailing in 19% and volar plate osteosynthesis in 55%. All ESIN were inserted in ascending technique. Complications occurred in 22% of patients and did not differ overall between techniques (p = 0.20). Severe complications were significantly more frequent after ESIN (20%) than after K-wires (7%) or plates (4%) (p = 0.04). Plate fixation achieved the most accurate alignment (≤5° angular deformity in 93% vs. 57% K-wires and 61% ESIN; p < 0.0001) and the fewest late motion restrictions (p = 0.02). K-wire surgery was fastest technique and required the least fluoroscopy, but necessitated the longest postoperative cast. Conclusions: Volar plating combines reliable anatomical reduction with a low rate of major complications and early mobilization, supporting its use in older children whose remodeling potential is limited. K-wires are a swift, minimally invasive option for younger patients, albeit with less precise reduction and prolonged immobilization. Conventional ESIN showed the highest burden of severe complications. Full article

Background/Objectives: The most common limb-salvage procedure for end-stage ankle arthropathy with severe bone defect is arthrodesis. Successful fusion requires rigid metal fixation, effective filling of the bone defect space, and maximal securing of the contact area between the tibia and talus. In cases with severe bone defect, sufficient grafting using autogenous bone alone is limited, and there is still controversy regarding the effectiveness of allogeneic or xenogeneic bone grafting. This study aimed to evaluate the intermediate-term clinical outcomes after shortening arthrodesis using fibular osteotomy for ankle arthropathy with severe bone defect. Methods: Twenty-two patients with shortening ankle arthrodesis were followed up ≥ 3 years. All operations were performed by one senior surgeon and consisted of internal fixation with anterior fusion plate, fibular osteotomy, and autogenous bone grafting. The causes of ankle joint destruction were failed total ankle arthroplasty (7 cases), neglected ankle fracture (6 cases), delayed diagnosis of degenerative arthritis (5 cases), avascular necrosis of talus (2 cases), and diabetic neuroarthropathy (2 cases). Clinical outcomes including daily living and sport activities were evaluated with the Foot and Ankle Outcome Score (FAOS) and the Foot and Ankle Ability Measure (FAAM). Radiological evaluation included fusion rate, time to fusion, leg length discrepancy, and degenerative change in adjacent joints. Results: The FAOS and FAAM scores significantly improved from a mean of 21.8 and 23.5 points preoperatively to 82.2 and 83.4 points at final follow-up, respectively (p < 0.001). Visual analogue scale for pain during walking significantly improved from a mean of 7.7 points preoperatively to 1.4 points at final follow-up (p < 0.001). The average time to complete fusion was 16.2 weeks, and was achieved in all patients. The average difference in leg length compared to the contralateral side was 11.5 mm based on physical examination, and 13.8 mm based on radiological examination. During the average follow-up of 56.2 months, no additional surgery was required due to progression of degenerative arthritis in the adjacent joints, and no cases required the use of height-increasing insoles in daily life. Conclusions: Shortening ankle arthrodesis using fibular osteotomy and anterior fusion plate demonstrated satisfactory intermediate-term clinical outcomes and excellent fusion rate. Advantages of this procedure included rigid fixation, preservation of the subtalar joint, effective filling of the bone defect space, and maximal securing of the contact area for fusion. The leg length discrepancy, which was concerned to be a main shortage, resulted in no significant clinical symptoms or discomfort in most patients. Full article

This study focuses first on the synthesis through an aza-Michael addition reaction of original linear diamine prepolymers and original amine/acrylate thermoset adhesives, and second on their thermal, mechanical and adhesion characterization. The major advantage of the aza-Michael addition reaction is that it takes place at room temperature, without a solvent and without a catalyst. Using the aza-Michael addition reaction, linear secondary diamine prepolymers were first synthesized with a control of the molecular weight, ranging from 867 to 1882 g mol⁻¹. Then, aza-Michael reactions of diamine prepolymers with three different acrylates allowed the synthesis of new amine/acrylate thermoset adhesives. All the thermoset adhesives were characterized by rheology and thermal analysis, leading, once the crosslinking aza-Michael reaction had occurred, to soft thermoset networks with glass transition temperatures ranging from −23 to −8 °C, gel point times ranging from 40 min to 4 h, and a polar component of the surface energy ranging from 3 to 17 mJ m⁻². Functionality of the acrylates directly influences the crosslinking rate, and a decreasing master curve is obtained when reporting crosslinking rate versus gel point time. Crosslinking density is controlled by the diamine prepolymer chain length. In a second step, thermoset adhesives were applied as thin films between two galvanized steel plates, and adhesion properties were evaluated through a lap-shear test. Results showed that the adhesive strength increases as the dynamic viscosity and molecular weight of the diamines prepolymer increases. Increasing the diamines prepolymer chain length results in an increase in strain at break, a decrease in the shear modulus, and a decrease in the maximum lap-shear strength. It is also observed that the adhesive strength decreases when the adhesive film thickness increases. Moreover, thermoset adhesives with high polarity and a surface energy similar to the surface energy of the substrate will favor high adhesion and a better adhesive strength of the assembly. Lastly, the nature of the acrylates and diamines prepolymer chain length allow tuning a wide range of adhesive strength and toughness of these original soft thermoset adhesives. Full article