Cross-sectional Size Research Articles

An enhanced simplified model for dynamic analysis of deployable Bennett linkages considering link cross-sectional size and contact

Deployable Bennett linkage has broad application prospects in engineering. Existing simplified models generally do not consider the link cross-sectional size and contact, and therefore, deviate from real-world Bennett linkages. This paper proposes an enhanced simplified model based on finite particle method (FPM) to consider link cross-sectional size and contact. Specifically, this model introduces virtual beams at the end cross-sections to consider the link cross-sectional size; furthermore, contacts between link surfaces, when Bennett linkage is fully folded or deployed, are considered by applying contact forces directly. The modeling methods for a single unit of Bennett linkage and an assembly are presented. The dynamic analysis method based on FPM is proposed for the enhanced simplified model, and the corresponding beam element, revolute hinge element, and contact element are derived. The dynamic responses of the unit of Bennett linkage are compared to those by the fine model to verify the proposed enhanced simplified model, and the influences of structural parameters are further investigated. The assembly of Bennett linkage is also analyzed to demonstrate the feasibility of the proposed method in the assembly of large-scale units. The numerical results demonstrate that the proposed method is effective and provides a promising approach for dynamic analysis of large-scale deployable Bennett linkages.

Study on buckling behavior of multilayer pyramid lattice structures

Three-dimensional lattice structures with high specific strength, specific stiffness and low apparent density, are widely employed across multiple engineering fields. Under uniaxial compressive loading, the lattice structure may experience local buckling or global buckling. This paper conducted a systematic parametric study of the various factors affecting the buckling behavior of multilayer pyramid lattice structures to investigate the mechanism of the two main instability modes, local and global buckling. It was found that the critical buckling load increases with the increase in the size of the unit cell and decreases with the increase in the total height of the structure for the same relative density. As the relative density increases, the buckling resistance of the lattice structure increases. It is possible to examine various buckling modes by varying the geometrical properties of the pyramid unit cell (slenderness ratio, rod inclination angle, cross-sectional size of strut connection parts). Finally, numerical simulations were performed to calculate the yield strength and buckling strength of the lattice structure under uniaxial compression load, in order to estimate the threshold relative density for structural buckling and yield failure. The results demonstrated that buckling failure should be considered for aluminum alloy pyramid lattice when the relative density is below 4.07%. This study provides design criteria for lattice structures dominated by buckling and offers ideas for improving the buckling capacity of truss-type lattice structures.

Targeting liver angiotensinogen using a GalNAc-siRNA improves cardiac remodeling in spontaneously hypertensive rats

Abstract Background Dysregulation of the Renin-Angiotensin-Aldosterone System (RAAS) leads to hypertension and cardiac hypertrophy. Angiotensinogen (AGT) is the only precursor of all angiotensin peptide products. Liver-specific AGT silencing has been proven to be a promising treatment option in lowering blood pressure (BP) in patients, characterized by full RAAS inhibition and little RAAS escape phenomena. However, the long-term effects of AGT knockdown on cardiac remodeling is still unclear. Purpose To explore the long-term effects of a GalNAc-conjugated siRNA drug R0797070 on AGT inhibition, BP and cardiac functions in Spontaneously Hypertensive Rats (SHRs). Methods In vitro inhibitory activities of siRNAs were assessed in primary rat hepatocytes. The selected siRNA was conjugated with GalNAc based on RIBO-GALSTAR liver targeting system and named R0797070. In vivo effects of repeated doses of R0797070 were evaluated in SHR model. The animals were treated with R0797070 (3 mg/kg, every 8 weeks; subcutaneous injection) or PBS (5 ml/kg, every 8 weeks; subcutaneous injection) for 7 months with the first dose (day1) at the 3 months of age. Captopril (100 mg/kg per day; oral administration) was taken as a positive drug control and Wistar rats were used as normotensive control group. Blood pressure was monitored by tail-cuff method after an initial acclimatization training period. Serum AGT protein was measured by ELISA and liver mRNA expression was detected by qPCR. Echocardiography was used to determine the changes of cardiac morphology and functions，and wheat germ agglutinin (WGA) staining was used to measure myocyte cross-sectional size. Results R0797070 showed 90-99% inhibitory activities on hepatic AGT mRNA at different doses. In SHRs, a single dose of R0797070 at 3 mg/kg resulted in a maximum inhibition of 97% for serum AGT protein with 27 mmHg mean blood pressure (MBP) reduction on Day 15. Daily administration of Captopril could reduce MBP by 33 mmHg on average, while the duration of drug efficacy of R0797070 could reach 2 months with the average 25 mmHg MBP reduction. At the end of study, the echocardiographic results showed that R0797070 significantly reduced left ventricular hypertrophy in the 10-month-old SHRs. Consistently, R0797070 treatment reduced the heart weight by 10%，and LV myocyte size by 17%. Conclusion We showed the long-term effects of a GalNAc-siRNA R0797070 on silencing angiotensinogen expression, reducing blood pressure and left ventricular hypertrophy. Compared to daily oral administration of Captopril and its effect on blood pressure R0797070 demonstrated significant effect on cardiac hypertrophy.Figure 1Figure 2

Cross-sectional data accurately model longitudinal growth in the craniofacial skeleton

Dense, longitudinal sampling represents the ideal for studying biological growth. However, longitudinal samples are not typically possible, due to limits of time, prohibitive cost, or health concerns of repeat radiologic imaging. In contrast, cross-sectional samples have few such drawbacks, but it is not known how well estimates of growth milestones can be obtained from cross-sectional samples. The Craniofacial Growth Consortium Study (CGCS) contains longitudinal growth data for approximately 2000 individuals. Single samples from the CGCS for individuals representing cross-sectional data were used to test the ability to predict growth parameters in linear trait measurements separately by sex. Testing across a range of cross-sectional sample sizes from 5 to the full sample, we found that means from repeated samples were able to approximate growth rates determined from the full longitudinal CGCS sample, with mean absolute differences below 1 mm at cross-sectional sample sizes greater than ~ 200 individuals. Our results show that growth parameters and milestones can be accurately estimated from cross-sectional data compared to population-level estimates from complete longitudinal data, underscoring the utility of such datasets in growth modeling. This method can be applied to other forms of growth (e.g., stature) and to cases in which repeated radiographs are not feasible (e.g., cone-beam CT).

Research Note: Muscle hypertrophy is associated with reversed sexual dimorphism in body size of quail

Sexual dimorphism is phenotypic differences between males and females in the same species. In general, males in most animals are larger than females at the same age, however, in quail, females have a larger body size with greater muscle mass than males. To understand what characteristics in muscle growth play roles in reversed sexual dimorphism in quail, the weights and the characteristics of the pectoralis major and gastrocnemius muscles (PM and GM, respectively) of male and female quail were compared in the current study. The data showed that 15-week-old female quail have significantly heavier bodies, and PM and GM weights compared to male quail (1.27-folds, 1.29-folds, and 1.16-folds, respectively). To compare muscle characteristics such as hypertrophy (increased size) and hyperplasia (increased cell number), the PM and GM were stained using hematoxylin and eosin, and then histological characteristics such as total cross-sectional area (CSA), number and size of myofibers, and muscle bundle of the muscles were measured and analyzed. In both PM and GM, there were no differences in total numbers of myofibers and muscle bundles as well as the average numbers of myofibers per bundle between sexes. However, the sizes of myofiber and the bundle were significantly increased in female compared to male (1.33-folds and 1.28-folds in PM, and both 1.23-folds in GM, respectively). The findings of the current study suggest that muscle hypertrophy in female quail, not hyperplasia, can be attributed to the sexual dimorphism in quail size.

Buckling behavior of Dendrocalamus sericeus Munro bamboo bars: Experiments and application

Bamboo is an alternative natural material that is widely used in engineering applications, especially in terms of sustainable construction. However, there are a few studies on the local bamboo's behavior, especially in northern Thailand. For an in-depth study on this local natural resource, this paper conducts experimental tests on the Dendrocalamus sericeus Munro bamboo (DSMB) bars to investigate the buckling behavior. The tests include the free-free resonance test (FFR), compression test, buckling load test, and microstructure experiments. A total of 108 long buckling specimens were provided, including variations in specimen length, moisture content, and cross-sectional size. There are two types of specimens, namely the dry and soak specimens, that were obtained from the Phayao province in Thailand and are 3–5 years old. From the experimental data, the statistical method is employed to investigate the distribution of these data and establish the modified Euler buckling stress for the prediction of the critical buckling stress of the DSMB bars. Finally, two numerical simulations were provided to validate the proposed model and present the DSMB bar application on the RC column. The analytical results show that the proposed equation yields acceptable results with the experiment at an R2 of 0.9402, while the numerical model shows that if the amount of DSMB bars is adequate, the DSMB bars can provide the equivalent load capacity as the steel bars.

Intelligent Generative Design for Shear Wall Cross-Sectional Size Using Rule-Embedded Generative Adversarial Network

Intelligent Generative Design for Shear Wall Cross-Sectional Size Using Rule-Embedded Generative Adversarial Network

Dynamic compressive response of gradient truss–core sandwich structure subjected to underwater shock loading

The dynamic compressive responses of a multi–layer sandwich structures with the truss core were studied experimentally and numerically under the underwater explosion shock loading. A three–layer truss-core sandwich specimen was designed and fabricated from the stainless steel. The density gradient between core layers is realized by changing the cross-sectional size of the truss members in the core layer. A water tank explosion testing device was employed to carry out the underwater explosion experiment. The finite element method was used to investigate the influences of the layered strategy of structures and the density gradient between core layers on the dynamic response. The results reveal that the density–decreasing sandwich panels CBA has the optimal underwater explosion resistance, and the explosion resistance increases as the decrease of the density gradient ratio.

Deformation mechanisms of β-Li in Mg–Li dual-phase alloy and effects of surface oxide layer

This study investigates the deformation mechanisms of β-Li micropillar prepared from a Mg–7Li dual-phase alloy with or without surface oxide layer. The β-Li micropillar with three cross-sectional sizes, 2.5 × 2.5 μm2, 4.0 × 4.0 μm2 and 5.5 × 5.5 μm2, are studied. The results show that the oxide layer improves the strength of micropillar due to the dislocation trapping effect. When increasing the micropillar size, the oxide layer having nanoporous structure becomes relatively thinner, and the strengthening effect resulting from the oxide layer decreases. Regardless of the existence of the surface oxide layer, all β-Li micropillars show continuous deformation characteristics. This is ascribed to the interactions between pre-existing dislocations and non-planar dislocations activated during compression, which induces low-angle grain boundary and effectively traps the dislocations at the central area.

Damage Analysis and Quality Control of Carbon-Reinforced Concrete Beams Based on In Situ Computed Tomography Tests

Carbon-reinforced concrete (CRC) is increasingly utilized in construction, due to its unique properties, such as corrosion resistance, high-tensile strength, and durability. Understanding its behavior under different loads is crucial to ensuring its safe and effective use in various construction applications. In this study, three-point bending tests were performed in combination with large-scale in situ computed tomography (CT). This paper presents the related three- and four-dimensional evaluation methods, with emphasis on crack width and quality control. The focus was on large CRC beams, with cross-sectional sizes of up to 80 mm by 160 mm. Such dimensions require extremely high energy during a CT scan. Therefore, a new experimental setup with energies of up to 8 MeV was used in this study. However, such high energies posed new challenges to the analysis methods. Therefore, two methods (digital volume correlation and grayscale profile analysis) for accurate crack width estimation were adapted and applied to the 3D reconstructions. In addition, a photogrammetric stereo image sequence was acquired and analyzed, using digital image correlation to cross-validate the results derived from the 3D crack width estimates. The 3D CT images also played a key role in the quality control measures, including the localization of the carbon-reinforcement and the assessment of porosity within the concrete structure.

Experimental Study on the Damping Performance of High-Strength Concrete Columns with Different Section Sizes

In this paper, structural columns with cross-section sizes of 100 mm × 100 mm, 75[Formula: see text]mm × 150 mm, and 85 mm × 121 mm are designed based on the same notional size of member. The acceleration signals of each column at axial compression ratio of 0.1, 0.2 and 0.3 were obtained by impact hammering. The corresponding frequency and damping ratio are obtained by half power wideband method. Based on the statistical method, the variation rules of acceleration signal characteristics, frequency characteristics and damping characteristics in different thickness directions under different axial compression ratios were analyzed. The correlation between frequency and damping ratio in different thickness directions with different axial compression ratios is discussed. The results show that under the same axial compression ratio, the damping ratio and frequency tend to decrease with the increase of the thickness in the tapping direction. Under the same thickness, the frequency decreases with the increase of the axial compression ratio. The damping ratio of the column decreases with increasing stress ratio when the thickness in the knocking direction is less than 100 mm. The damping ratio of the column increases with the increasing stress ratio when the thickness in the knocking direction is equal to 100 mm. The damping ratio of the column increases slightly with the increasing stress ratio when the thickness in the knocking direction is greater than 100 mm. By fitting the discrete data, the frequency variation range is 229.65–511.07 Hz, and the range of the damping ratio variation is 0.1–0.5%.

Statistical law of laser echo disturbance characteristics under atmospheric turbulence

AbstractAtmospheric turbulence significantly affects laser transmission and echo. The size of the echo cross section and the distribution of energy are important parameters to obtain target information. In this paper, the speckle characteristics of laser echo are analyzed using field experiments with different detection distances. The energy attenuation law is observed, and the statistical law governing the cross-sectional area and energy of the echo light spot is determined based on the time variability of atmospheric turbulence. The research shows that in order to obtain stable return laser beam interference information, the current weather situation and the strength of atmospheric turbulence should be considered, and the corresponding interference region should be selected according to the detection distance. Although the size and energy of the echo cross section are directly affected by the detection distance, the variation trend remains consistent and indicates a clear statistical law that provides a strong basis for laser interferometry.

Fast Adiabatic Mode Evolution Assisted 2 × 2 Broadband 3 dB Coupler Using Silicon-on-Insulator Fishbone-like Grating Waveguides.

We report a novel 2 × 2 broadband 3 dB coupler based on fast adiabatic mode evolution with a compact footprint and large bandwidth. The working principle of the coupler is based on the rapid adiabatic evolution of local eigenmodes of fishbone-like grating waveguides. Different from a traditional adiabatic coupling method realized by the slow change of the cross-section size of a strip waveguide, a fishbone waveguide allows faster adiabatic transition with proper structure and segment designs. The presented 3 dB coupler achieves a bandwidth range of 168 nm with an imbalance of no greater than ±0.1 dB only for a 9 μm coupling region which significantly improves existing adiabatic broadband couplers.

Corrosion state assessment of the rebar: Experimental investigation by ambient temperature and relative humidity

One of the most crucial elements affecting the durability and stability of concrete construction is steel rebar corrosion. The primary cause of structural degradation in buried rebar is the generation of corrosion byproducts and the resulting volume expansion. The increased volume of the rebar within the concrete can exert tensile forces, leading to crack formation and concrete spalling. Therefore, the evaluation and prevention of rebar corrosion play a crucial role in ensuring the longevity and stability of structures, addressing concerns regarding their service life and structural integrity. The objective of this study is to measure and analyze the voltage potential at the target corrosion rate of the steel rebar. To achieve the precise target corrosion rate of the rebar, image processing was employed to measure the corrosion rate. By eliminating light reflection and noise, image processing enabled precise calculations based on the extracted corroded portions of the rebars. To evaluate the influence of temperature and relative humidity on the surface corrosion rate, voltage potential measurements were conducted. The results revealed that the voltage potential exhibited minimal sensitivity to temperature variations. However, it displayed a significant response to changes in relative humidity. Notably, smaller-diameter steel rebars exhibited increased variations in voltage potential in accordance with changes in the rate of relative humidity. This can be attributed to the small diameter and cross-sectional size of the steel, which facilitate electron mobility and, consequently, exhibit a high sensitivity to environmental changes.

Effect of microstructure refinement of pure copper on improving the performance of electrodes in electro discharge machining (EDM)

The paper presents an analysis of the impact of plastic deformation using hydrostatic extrusion (HE) on the structural, mechanical and functional properties of pure copper for use as electrodes in the process of electro discharge machining (EDM). As part of the research, copper was subjected to the HE process with the maximum cumulative true strain equal to ɛcum = 3.89 obtained in 5 stages. The result was, a refinement of the microstructure with the grains elongated in the direction of extrusion, with a cross-sectional size of d2 = 228 nm. As the obtained material can be potentially used in the process of electro discharge machining, the copper specimens after the HE process were subjected to a comprehensive analysis to determine the mechanical, physical and functional properties of the material. A significant increase in strength (UTS) and yield strength (YS) of the HE-processed copper was obtained, reaching respectively UTS = 464 MPa and YS = 456 MPa at the maximum strain of ɛ = 3.89. Despite the clear strain-induced strengthening of the material, a very high electrical conductivity of not less than 97% was obtained. The electrodes made of copper after HE process have reduced erosion wear while maintaining a comparable or better quality of the machined surface. The best results were obtained for finish machining, where the electrical discharge wear was lower by 60% compared to the electrode made of non-processed copper. In addition, an improvement in the surface quality after the EDM process by 25% was observed when using the HE-processed electrodes.

Applying fully convolutional networks for beam profile and emittance measurements

The transverse cross-sectional size and emittance are critical beam parameters that characterize the performance of the accelerator and assess the state of the beam. Inspired by the success of machine learning in image processing tasks, we have crafted a bespoke measurement system with a primary focus on accurately determine the transverse cross-sectional size and emittance of the beam. The system utilizes a beam spot detector to convert the beam spot to a light spot image, which is then projected onto the CCD camera through the telecentric lens for the acquisition. The image data collected by the camera is subsequently imported into the EPICS database developed based on ADAravis software. We employ the Gaussian fitting technique on the collected images to accurately calculate the cross-sectional size of the beam. Furthermore, by incorporating the four-level iron scanning method, the lateral emittance of the beam is calculated in a comprehensive manner. To suppress the salt and pepper noise introduced due to the presence of dark current and beam shooting phenomena on the transmission line, we propose a novel fully convolutional neural network (FCN) design with preactivated residual units. The test conducted at HLS-II confirms that the measurement uncertainty of this system is superior to 27.5 μm. Moreover, when operating at an electron beam energy of 800 MeV, the measured emittance of the accelerator is found to be 38.515 nm·rad, a value closely aligning with the theoretical value of 36.2 nm·rad. These compelling results provide strong evidence supporting the reliability of the emittance measurement algorithm, making it suitable for deployment in the forthcoming terahertz accelerator.

Calculation of the Tubular Elements Made of Pressed Profiles

This paper is dedicated to ensuring the strength of cargo equipment elements of transport aircraft. The strength of rollers of roller conveyors, which are made of standard pressed aluminum tubular profiles or composite tubular elements, is considered. The main disadvantage of these semi-finished products is the deviation of the diameter of these standard aluminum profiles, which leads to the emergence of eccentricity Δ between the axes of the outer and inner surfaces. The influence of eccentricity on the change in the values of normal and tangential stresses is considered. This analysis was carried out for standard diameters of tubular profiles at values Δ equal to half of the standard limit deviation of the outer diameter D. Calculations of normal and tangential stresses and their comparison with nominal stresses that occur in the absence of misalignment have been carried out. Calculations were made of the value c of the removal of the center of rigidity from the center of the circle of the outer border of the cross-section at different cross-section sizes of standard profiles with values of Δ equal to half of the standard limit deviation of the outer diameter D inclusively. The calculations showed an increase in tangential stresses τ in some cases by 64% and even by 213%. The obtained results indicate that the presence of Δ≠0 will have a negative effect on the resource of these elements. In order to eliminate the negative consequences, it is necessary to increase the requirements for the shape deviation of the tubular profiles in the input control.

THE MECHANICAL PERFORMANCE OF PARALLEL TDG BAMBOO LAMINATED COLUMNS (TDGLC)

A research study conducted in Thailand aimed at developing and adding value to agricultural products, specifically focusing on bamboo. The agricultural sector in Thailand plays a significant role in the economy and society, employing a large portion of the population and generating income equal to approximately 9% of the countrys GDP. The government aims to enhance the competitiveness of Thai agricultural products and increase their value for the benefit of local communities.The research focuses on utilizing bamboo for construction projects, particularly in the form of Thai Dendrocalamus Giganteus bamboo (TDG) laminated columns (TDGLC). The study involves a production process to create man-made TDGLC and investigates the mechanical properties of these columns. The research examines the performance of parallel bamboo laminated columns under axial compression tests.Specimens of TDG bamboo, aged between 3 and 4 years, were cut into strips and clamped together to form columns of various lengths and cross-sections. The cross-section sizes ranged from 100 mm to 203 mm, with lengths of 1 meter, 2 meters, and 3 meters. The compression load and classification of long and short columns were analyzed based on the proportioning of length and cross-section.The research identified specific column types that exhibited either strength failure (short columns) or buckling failure (long columns). However, two column types, C603 and C402, showed mixed results, with both strength and buckling failures. Although their slenderness ratios exceeded 60, the primary mode of failure indicated that these specimens should be classified as short columns.It was observed that defects in the specimens influenced their load capacity, with higher slenderness ratios resulting in greater lateral deflection corresponding to the peak load. The equation used to calculate the load capacities aligned well with the test results. Overall, the study contributes to the understanding of TDGLC performance in construction applications and provides insights into the mechanical behavior of bamboo columns under axial compression.

Discrete sizing optimization method based on dividing rectangles algorithm and local response surface for steel frame structures

It has always been the goal of structural engineers to construct safe and stable buildings using the least amount of materials. Utilizing a quick and effective way to optimize the cross-section size is crucial because conventional building design methods are impacted by the designers' knowledge, and it is challenging to prevent material waste. Due to its implicit optimization function, discrete design variables, and expensive individual evaluation, sizing optimization of high-rise buildings is very challenging to achieve. In order to effectively handle this optimization problem, a two-stage discrete sizing optimization method for high-rise buildings based on the DIviding RECTangles (DIRECT) algorithm and local response surface is proposed in this paper. The optimization method suggested in this research consists of two key stages: the global search stage and the local search stage. In the global search stage, the entire design domain is divided using a modified DIRECT algorithm to swiftly identify potentially optimal subregions that may contain the best points. In the local search stage, the local response surface model is constructed to approximate the objective and constraint functions using the sampling points from the previous stage, and the discrete optimal solution is rapidly found through mathematical iterative solving. A sizing optimization calculation program for high-rise buildings was developed in Microsoft Visual Studio 2015 on the basis of C++ to achieve automatic optimization. The new method was applied to optimize three high-rise steel frame buildings with different heights and plan shapes. The results showed that the material cost could be successfully saved compared with the conventional design, and the over-limit constraints could be adjusted automatically, which demonstrated the viability and efficacy of the two-stage optimization method.

Localised Web Bearing Behaviour of Cold-Formed Austenitic Stainless-Steel Channels: Review of Design Rules and New Insight under Interior Loading

Stainless steels are modern high-performance construction materials exhibiting excellent corrosion resistance, recyclability, ductility, and durability which make them appealing to use in the construction industry. However, when used as structural sections, they are subjected to localised failure in the web. This study aims to examine the structural behaviour of cold-formed low-carbon content standard austenitic 304L and 316L stainless steel channels under localised interior bearing loads. The results of 21 tests on unlipped channels with different cross-section sizes and thicknesses are presented. A nonlinear quasi-static Finite Element (FE) model is then developed. The FE model is validated against experimental test results and demonstrated good agreement in terms of bearing strength and failure modes. In addition, the experimental and FE results are used to compare the results against the results predicted in accordance with the American specification SEI/ASCE 8:2002 and European Standard EN 1993-1-4:2006. It is found that the current design equations are unreliable and too unconservative to use for cold-formed austenitic stainless steel unlipped channels, especially when compared to SEI/ASCE 8:2002, as much as 41%.