Structural Performance Research Articles

Structural simulation and performance evaluation of self-priming electrostatic diesel vehicle emission particle sensor

Here is reported a self-priming electrostatic particulate matter (PM) sensor for real-time monitoring of diesel exhaust under different operating conditions. Initially, a multi-physics coupling model for the sensor was established. By varying the exhaust flow and temperature, the emissions of diesel vehicles were simulated to evaluate the sensor. The results showed that within the typical velocities (5 to 60 m/s) and temperature ranges (100 to 500 °C) of diesel exhaust, the sensor outlet pressure was consistently below the inlet pressure, with a maximum differential pressure of 259 Pa, indicating the capability for self-priming sampling of exhaust under different operating conditions. Additionally, the calibration platform was constructed using a miniature inverted soot generator which produced a series of samples to calibrate the relationship between current and mass concentration with a correlation coefficient of 0.99. From 0 to 100 mg/m3, the PM sensor exhibited a relative error between −6.00% and 6.00% with good stability and consistency for samples of different sizes and concentrations, with correlation coefficients exceeding 0.98. The results between the self-developed sensor and a commercial instrument revealed that the former provided high-precision real-time measurement of diesel exhaust.

Effect of Ownership Structure on Performance of Quoted Financial Firms in Nigeria

This study investigates the relationship between ownership structure and firm performance of quoted Nigerian financial firms in Nigeria. This study employs an Ex post facto research design, utilizing data extracted from annual reports of the financial firms listed on the Nigerian Exchange Group (NGX) between the years 2014 to 2023. The population of interest consists of 48 listed financial firms. Secondary data from the firms' annual reports were collected and analyzed using fixed effect panel regression analysis as specified by Hausman test. The findings reveal significant positive effects of managerial ownership, institutional ownership, and ownership concentration on firm performance. These results align with established theories such as agency theory and stewardship theory, as well as previous empirical studies in the field of corporate governance and ownership structure. The study concludes that increasing managerial ownership can align the interests of managers with shareholders, leading to improved firm performance. Attracting institutional investors who bring expertise, monitoring capabilities, and long-term investment perspectives can also contribute to enhanced firm performance. Furthermore, careful management of ownership concentration can enhance monitoring and decision-making efficiency, align shareholder interests, and reduce agency costs. However, the study finds no significant impact of foreign ownership on firm performance in the Nigerian context. This suggests the need for further research to better understand the specific dynamics and potential implications of foreign ownership in the Nigerian financial industry, considering factors such as regulatory restrictions, cultural differences, and information asymmetry.

Strength, pliability, and hydrophobicity of mung bean starch straws: Orientation change caused by annealing time.

To achieve starch straws with high strength and large toughness, the effects of annealing time on structural and functional performances of mung bean starch straws were studied. The results revealed that with increasing annealing time from 0to 60min, the ratios of 1047cm-1/1022cm-1 in Fourier transform infrared spectroscopy decreased from 1.37 to 1.20, and the relative crystallinities decreased from 12.09% to 11.01%. The relative crystallinity increased to 13.28% when annealing time increased to 120min. The maximum bending force increased from 10.93 to 104.24 N, and modulus of elasticity enhanced from 0.93 to 62.68 N/mm when annealing time increased from 0 to 120min. Starch straws annealed for 120min had the lowest water absorption (94.61%), while starch straws annealed for 60min had the highest water absorption (127.38%). This outcome not only lay a theoretical foundation for preparing biodegradable starch straws with excellent performance, but also apply for beverages, food container, food packaging films, and so on, strongly promoting starch industrial transformation and development.

Biomineralization and biomechanical trade-offs under heterogeneous environments in the eastern oyster Crassostrea virginica

ABSTRACT Accurate biological models are critical to reliably predict vulnerability of marine organisms and ecosystems to rapid environmental changes. Current predictions on the biological impacts of climate change and human-caused disturbances primarily stem from controlled experiments but lack assessments of the mechanisms underlying biotic variations in natural systems, especially for habitat-forming, climate-sensitive species with key ecological roles. This study aimed to characterize and quantify spatial patterns of shell biomineralization and biomechanical properties in a key reef-building oyster, Crassostrea virginica, collected from restored reefs along natural estuarine gradients in the Hudson River Estuary (NY, USA). We characterized patterns of oyster shell deposition, structure, composition and mechanical performance at the macro- and microscale. Eastern oysters show a strong capacity for adjustments in shell biomineralization and biomechanics to maintain shell production and protective functions. We reveal salinity as a key predictor of oyster shell structure, mechanical integrity and resistance to dissolution, and describe the functional role of chalky calcite in shaping shell mechanical performance. Changes in shell production along salinity gradients indicate formation of shells with (1) high mechanical resistance but increased vulnerability to dissolution under marine conditions and (2) lower structural integrity but higher protection from dissolution under brackish conditions. Our work illustrates that biomineralization and biomechanical trade-offs may act as mechanisms in eastern oysters to maintain overall performance under heterogeneous estuarine environments and could represent a cornerstone for calcifying organisms to acclimate and maintain their ecological functions in a rapidly changing climate.

Structural Performance of Bamboo Sandwich Panel (BSP) With Openings as Load Bearing Wall

Structural Performance of Bamboo Sandwich Panel (BSP) With Openings as Load Bearing Wall

Evaluation of glass fiber-reinforced polymer bars for application in sections of reinforced concrete

In order to evaluate the effectiveness and acceptability of glass fiber reinforced polymer (GFRP) bars as a substitute for conventional steel reinforcement, this study looks into their use in reinforced concrete sections. To assess the mechanical qualities of GFRP bars, the research includes mix design, casting, and extensive testing, such as flexural and tensile tests. Furthermore, a comprehensive study of GFRP-integrated reinforced concrete building sections is carried out, looking at factors like primary stresses, bending stresses, shear stresses, and deflection. Additionally, using ANSYS software, a comparative study of beam-column junctions using GFRP and RCC sections is conducted to evaluate structural performance under various loading circumstances. The results demonstrate how GFRP bars can improve building projects' structural integrity, toughness, and sustainability

Comparative Study of Pre-Engineered Building with Varying Wind Speed

This research explores the structural performance of Pre-Engineered Buildings (PEB) using STAAD-Pro software, specifically analyzing the effects of different wind speeds. The wind analysis follows the guidelines of IS 875 (Part III) – 2015, with an emphasis on optimizing steel usage in warehouse structures of sizes 20×100 m, 30×100 m, and 40×100 m, situated in three locations: Mumbai, Delhi, and Mysore. The wind speeds considered for these locations are 44 m/s in Mumbai, 47 m/s in Delhi, and 33 m/s in Mysore. The objective of the study is to examine how varying wind speeds affect PEB design and to optimize steel usage for these structures.

Flexural behaviour and post-cracking performance of polypropylene fibre-reinforced waste cardboard blended concrete

The requalification of recycled materials has become of significance owing to a global shift towards net zero emissions and the severe environmental impact of misused recyclable waste. Cardboard and polypropylene have evolved into significant waste products, and the purpose of the study was to focus on the repurposing of both waste materials in determining the structural behaviour of an eco-efficient fibre-reinforced waste concrete. The study extended upon the findings of a precursor study in the development of an eco-efficient fibre-reinforced waste concrete mix. Finely processed municipally collected waste cardboard and recycled polypropylene macro-fibres were incorporated into a concrete mix design for which an experimental program was realised. To achieve this, uniaxial compressive strength, modulus of rupture, modulus of elasticity, and indirect tensile strength of the waste and reference mixtures were determined for 7- and 28-day intervals. Crack mouth open displacement testing was achieved to assess the post-cracking response, and retaining wall beams were prepared and loaded to determine the efficacy of the concrete mixture for low load-bearing structures. Mechanical and post-cracking properties of the hybrid waste concrete underscored excellent performance in comparison to other waste fibre-reinforced concrete mixtures, and superior to those blended with similar kraft fibre volume fractions. Moreover, the structural performance of beams cast from the hybrid mixture closely matched those of the reference mixture, emphasising the viability of the mixture and the role waste materials have in the construction and building industry.

Structural behaviour of hollow core reinforced concrete (HCRC) short column under static load

The high strength-to-weight and low self-weight ratio of Hollow Core Reinforced Concrete (HCRC) short columns have made them a popular choice for application in construction. Nevertheless, little is known about how HCRC short columns behave when subjected to static loads. This is because HCRC short columns are a relatively recent type of structural member, and there has been little research into how well they behave when subjected to static loads. Given that HCRC short columns are made of composite material, it poses one of the difficulties in understanding their behaviour when subjected to static load. The complex relationship between the steel reinforcement and concrete core potentially affects the column’s ability to support loads and failure more. The purpose of this research is to evaluate their failure mechanisms and assess the structural performance under static load. Finite element models with different configuration are modelled which can simulate the complex behaviour of reinforced concrete structures under static load. This study found that Square Hollow Core (SHC) and Circular Hollow Core (CHC) are known as the most affected columns in terms of displacement compared to Rectangular Hollow Core (RHC). Stress was critically found at the top section of the column and it reduced towards lower section. The finding is able to optimize load-bearing efficiency, reduce material usage, enhance stability, improve resistance, and be proposed as modern structural applications.

Intangible Asset Structure and Financial Performance of Non-Financial Firms Listed at Nairobi Securities Exchange, Kenya

The Kenyan listed firms have immensely contributed to the country’s economy. However, poor financing decisions have led to most firms’ failure, which has in turn posed a big dilemma to researchers, business managers, as well as investors. Past research relating intangible asset structure and financial performance have also presented mixed results. Therefore, this study purposed to establish the relationship between intangible asset structure and financial performance of listed non-financial firms operating in Kenya. Thirty (30) non-financial firms were targeted as population of the study and were selected using census sampling technique as a unit of analysis. The findings yielded that there was a positive relationship between intangible assets and non-financial firms listed at NSE; with a model as follows Y = 7.042 + 0.675X + ԑ It was therefore concluded that managing intangible asset structure contributed betterment and profitability of non-financial firms’ listed at Nairobi Securities Exchange, Kenya.

Ratiometric optical temperature sensing properties based on up-conversion luminescence of novel NaLaTi2O6:Yb3+,Er3+/Ho3+ phosphors

To satisfy the increasing necessity of contactless optical thermometry, utilizing both thermally coupled (TCLs) or non-thermally-coupled (NTCLs) energy levels of rare earth ions in novel phosphors has significant potential for devising the optical thermometers with high temperature sensitivity. Herein, a sequence of novel Yb3+,Er3+/Ho3+ doped NaLaTi2O6 (NLTO) phosphors were sintered using a high-temperature solid-state reaction approach. Structure, phase component and luminescence performance were identified in detail. Upon 980 nm near-infrared (NIR) excitation, the obtained materials presented typical Er3+/Ho3+ characteristic emission wavelengths in visible region, which include two green emission bands around 522 and 543 nm, as well as a weaker red band around 661 nm for Er3+ doped NLTO, a green emission band around 545 nm and a red band around 657 nm for Ho3+ doped NLTO. Besides, a unusual emission band around 757 nm of Ho3+ in visible edge region was also clearly found. The temperature sensing properties of representative NLTO:Yb3+,Er3+/Ho3+ samples were assessed based on the fluorescence intensity ratio (FIR) technique of TCLs or NTCLs energy levels. The maximal absolute sensitivity (Sa) and relative sensitivity (Sr) were determined to be 0.0374 K-1 (293 K) and 0.970% K-1 (293 K) by taking the FIR of NTCLs 2H11/2→4I15/2 and 4F9/2→4I15/2 transitions in NLTO:Yb3+,Er3+. Simultaneously, the maximal Sa and Sr were 0.0306 K-1 (573 K) and 0.776% K-1 (373 K) using the FIR of NTCLs 5F5→5I8 and 5F4,5S2→5I7 transitions in NLTO:Yb3+,Ho3+. Consequently, the temperature sensitivities above can be compared to reported results, which indicate that as-prepared materials have a promising application in optical temperature sensors field.

Mechanism based four-linear cohesive zone model for mode I fracture of different stacking sequence CFRP laminates

Delamination, a prevalent failure mode observed in laminated composites, exerts a significant impact on structural integrity and performance. The occurrence of fiber bridging during the fracture process adds complexity and elevates the research challenges associated with this phenomenon. Existing models exhibit limitations in accurately capturing bridging behavior and discerning its underlying mechanical mechanisms. This study addresses these limitations by analyzing experimental results, employing the J-integral, and analyzing R-curve behavior, proposing a mechanism-based four-linear cohesive zone model along with a new finite element implementation method. Comprising three overlapping bi-linear CZMs, this model effectively simulates mode I fracture behavior in laminates with different stacking sequences. Moreover, it intuitively illustrates the mechanical mechanisms during crack propagation and offers simplicity in implementation. This research contributes to a deeper understanding of composite fracture mechanics and provides a practical model for predicting delamination behavior in laminated structures.

Tailored proton conductive membranes of PVdF-co-HFP: Investigating the synergistic effects of ammonium tetrafluoroborate and phosphoric acid dopants on dielectric characteristics

This study investigates the structural, thermal, and dielectric properties of pure PVdF-co-HFP matrix and its composite electrolytes, PVdF-co-HFP/NH4BF4[x], both before and after PA doping, using FTIR, SEM, TGA, and dielectric analyses. FTIR spectra reveal characteristic vibrational bands, confirming the presence of various functional groups and phases. SEM images display a smooth and homogeneous surface morphology for pure PVdF-co-HFP, while the composite electrolytes exhibit irregular dispersion of NH4BF4 salt and rougher surfaces upon PA doping. TGA analysis shows that the onset of thermal degradation occurs at approximately 370 ℃ for pure PVdF-co-HFP, while PA-doped samples demonstrate higher decomposition temperatures, exceeding 400 ℃ due to hydrogen bonding and ionic complex formation. The presence of NH4BF4 and PA doping also affects the crystallinity of the PVdF-co-HFP matrix, notably shifting the transition temperatures of the alpha and beta phases. Ionic conductivity measurements indicate that PA doping significantly enhances conductivity by increasing charge carrier concentration and facilitating ion transport. PA-doped PVdF-co-HFP/NH4BF4[10] showed the highest conductivity reaching 1.68 × 10−3 S.cm−1 at 1 MHz and 400 K. Dielectric studies reveal frequency-dependent behavior, with dielectric constant (ε') and loss (ε") showing distinct trends influenced by salt concentration and PA doping. The dielectric tangent loss (tanδ) of PA-doped PVdF-co-HFP/NH4BF4 composite membranes exhibits frequency and temperature dependence. At higher temperatures, tanδ increases with frequency, showing a resonance peak that shifts towards higher frequencies. The study elucidates the impact of PA doping on the structural, thermal, and electrochemical performance of PVdF-co-HFP/NH4BF4 composites, providing insights for their potential applications in advanced electrolyte systems.

Design and experimentation of width tapered meandered array structure for low frequency broadband vibration energy harvesting

A novel 6DoF Tapered beam energy harvester, capable of operating across a broad and low frequency range, is proposed in this work. The hybrid structure incorporates regular beam array and zig-zag sections, enhancing deformation and bending. Width tapering with constant thickness optimizes the structural performance and energy harvesting capabilities of the beam. Tapering ensures even strain distribution, reducing the risk of structural failure. The proposed structure demonstrates wide band characteristics at low frequencies, delivering higher power output compared to an array of cantilevers for a given area. FEM analysis is conducted to optimize proof mass, aiming for closely spaced resonance frequencies and high-power output. Experimental validation on a prototype confirms the accuracy of the frequency response predicted by the models. Under harmonic base excitation of 0.4 g, the harvester yields an average DC power of 2497 μW, accounting for signal conditioning losses, within the frequency range of 9–20 Hz. The suggested structure offers excellent design flexibility, allowing adjustment of resonant frequencies by varying the number of beams, the slope and the proof mass of individual beams. The geometry of the proposed structure provides versatility, mechanical resilience, uniform strain distribution make it suitable for developing MEMS energy harvesters.

Optimization of Shear Resistance in Horizontal Joints of Prefabricated Shear Walls through Post-Cast Epoxy Resin Concrete Applications

The horizontal joint is a critical component of the prefabricated shear wall structure, responsible for supporting both horizontal shear forces and vertical loads along with the wall, thereby influencing the overall structural performance. This study employs direct shear testing and finite element analysis to investigate the horizontal joint in walls with ring reinforcement. It examines the impact of various factors on joint shear performance, including the type of joint material, joint configuration, buckling length of ring reinforcement, strength of precast concrete, reinforcement ratio of ring reinforcement and dowel bars, and the effect of horizontal binding force. The findings indicate that the shear bearing capacity and stiffness of joints incorporating post-cast epoxy resin concrete and keyways are comparable or superior to those of integrally cast specimens. A larger buckling length in ring reinforcement may reduce shear strength, suggesting an optimal buckling length at approximately one-third of the joint width. As the strength of precast concrete increases, ductility decreases while bearing capacity increases, initially at an increasing rate that subsequently declines. Optimal results are achieved when the strength of precast concrete closely matches that of the post-cast epoxy concrete. Enhancing the reinforcement ratio of ring reinforcement improves shear capacity, but excessively high ratios significantly reduce ductility. It is recommended that the diameter of ring reinforcement be maintained between 10 mm and 12 mm, with a reinforcement ratio between 0.79% and 1.13%. Increasing horizontal restraint enhances stiffness and shear capacity but reduces ductility; thus, the axial compression ratio should not exceed 0.5.

Multiscale modelling of CFRP composites exposed to thermo-mechanical loading from fire

Carbon fibre reinforced polymers (CFRP) are prone to structural damage during extreme events such as fire. Typically, modelling the effect of fire on CFRP structures is carried out through mesoscale analysis to predict overall structural performance. In this study, Finite Element (FE) modelling has been conducted to investigate the effects of fire on CFRP specimens at both meso- and micro-scales. The mesoscale analysis informs the microscale analysis to examine the effects of fire on each constituent of the material. A comparison of thermal analysis at the meso- and micro-scales reveals less than a 6% difference in the predicted nodal temperature. For the first time, fire-induced progressive failure analysis has been conducted on the fibres, matrix, and fibre/matrix interface of representative plies within the composite laminates. Fibre breakage, matrix cracking, and interface debonding were accurately captured using representative volume element (RVE) models under thermo-mechanical loading, showing qualitatively excellent agreement with experimental data.

A Compact All-Band Spacecraft Antenna with Stable Gain for Multi-Band GNSS Applications

This study presents a compact and stable gain spacecraft antenna that operates in all Global Navigation Satellite System (GNSS) bands from 1.164 GHz to 1.610 GHz. The proposed antenna structure based on the single-feed crossed bowtie antenna concept consists of four triangular patches excited with a 90° phase difference in between to generate right-hand circular polarization (RHCP), without needing complex feed networks. The radiator part of the antenna is covered by a radome and is also supported by a cylindrical dielectric cavity frame (DCF) to weaken the diffracted waves propagating along the ground plane while increasing vibration resistance. The fabricated antenna provides a return loss better than 10 dB with lower than 3 dB axial ratio and a stable gain around 7.2 ± 0.3 dBic over the entire GNSS bands, as well as a more compact and lightweight structural performance. It is also verified that the structural integrity and functional performance of the fabricated antenna remain consistent despite exposure to an equivalent vibration level in the launch process. The presented all-band spacecraft GNSS antenna is an innovative implementation with space industry insight for multi-band space applications that have application-specific limitations and provides consistent performance, as well as operational safety with the antenna design simplicity.

Sensibility Analysis of Traditional Span Frame

ABSTRACT Traditional timber frames may have a complex mechanical behavior regarding to today engineer skills and design standards. For an identical rebuilding as required for the Notre-Dame de Paris Cathedral, accurate modeling must be performed to assess modern reliability. Identical rebuilt means same green oak material, same geometry and timber connections. In the context of the rebuilt of the Notre-Dame carpentry, a part of the timber frame based on the original schemes of the nave extracted from historical graphic document was reproduced. A full-scale replica was erected in order to perform mechanical tests. Through an in-situ monitoring, this structure represents a case study in order to provide data relative to the kinetics of displacements. This investigation allows to evaluate the global behavior of the structure. Based on the finite element method (F.E.M), a dedicated model is used to analyze the sensitivity of the material properties, the beam geometry and the wood-to-wood connections in order to design the testing carried out on the wooden structure. From these full-scale tests, we determine the real stiffness of the carpentry. Then, a retro-analysis was proposed to evaluate the axial stiffness of connections according to the corresponding finite element model, by fitting data to reproduce the real displacements. The study reveals that this property is substantial to describe the global behavior. Furthermore, we carried out in the laboratory an experimental campaign consisting in characterizing traditional joints. The goal was to estimate their stiffness and their specific failure modes by using image correlation. Concomitantly, numerical simulations were developed in order to investigate the dependence of the stiffness according to moisture content variation of oak species. The global research supplies useful tools and results, which may be able to improve the understanding of the mechanical performance of traditional structures and provide valuable information for design purposes.

Superior Electrochemical Sensor Application of Co3O4/C Heterostructure in Rapid Analysis of Anticancer Drug Palbociclib in Pharmaceutical Formulations and Biological Fluids.

In this work, we report a study examining how different salt concentrations affect the structure and electrochemical performance of two Co3O4/C materials designed for the fabrication of an easy, cheap, fast, safe, and useful electrochemical sensor for the detection of Palbociclib (PLB). Co3O4 nanoparticles were successfully created by encapsulating them in N-doped amorphous carbon matrices by using the molten salt-assisted approach. In this process, different amounts of potassium iodate and zeolitic imidazolate framework-12 (ZIF-12) were used, followed by pyrolysis at 800 °C. Optimum Co3O4 embedded porous carbon structures were obtained, and the composite with the highest electrochemical properties was modified to a glassy carbon electrode (GCE) surface for PLB detection. The linear response spanned from 1.0 to 5.0 μM, featuring a limit of detection (LOD) of 0.122 μM and a limit of quantification (LOQ) of 0.408 μM; the correlation coefficient was calculated as 0.995. The high sensitivity of the method in detecting PLB in pharmaceutical samples and human urine demonstrated its feasibility, with recovery percentages ranging from 99.3% to 101.3% and relative standard deviation (RSD) values of <3%. Therefore, this technique will make a significant contribution to monitoring and improving existing cancer treatment options.

Assessment of Breakwater as a Protection System against Aerodynamic Loads Acting on the Floating PV System

Offshore floating photovoltaic (FPV) systems are subjected to significant aerodynamic forces, especially during extreme wind conditions. Accurate estimation of these forces is crucial for the proper design of mooring lines and connection systems. In this study, detailed CFD simulations were performed for various PV panel configurations, and using these CFD simulation correlations were developed to estimate lift and drag forces as a function of the number of panels. These correlations provide valuable tools for designing large-scale FPV systems with multiple PV modules. Additionally, this study investigates the potential of using breakwaters to reduce aerodynamic forces on FPV systems. Breakwaters, typically used to mitigate wave impacts, can also serve as wind barriers, significantly reducing wind forces before they reach the FPV array. Aerodynamic simulations with and without a breakwater were conducted using CFD to assess this effect. The results show a substantial reduction in lift and drag coefficients, especially for angles of attack up to 10 degrees, demonstrating the effectiveness of the breakwater in protecting the FPV system. However, beyond this threshold, the effectiveness of the breakwater of 2 m reduces. These findings highlight the importance of strategic breakwater placement and heights and their role in enhancing FPV system resilience. The insights gained from this study are critical for optimizing breakwater design and placement, ensuring the structural integrity and performance of FPV systems in varying environmental conditions. The data generated will also contribute to future design improvements for floating PV systems.