Variable Mesh Size Research Articles

Controlled stiffness and diffusivity of poly(ethylene glycol) hydrogel formed with cellulose-nanofiber framework

Hydrogels composed of polymer networks are widely used in industry and scientific research for high water retention and unique mechanical properties. Nevertheless, in ordinary hydrogel formation, the trade-off relationship between stiffness and mesh size remains a crucial consideration for practical applications. This study describes a facile approach to controlling hydrogel stiffness and mesh size by hybridizing poly(ethylene glycol) diacrylate (PEGDA) and methacrylated TEMPO-oxidized cellulose nanofibers (T-CNFMA). After disintegrating T-CNF by ultrasonication, T-CNFMA was synthesized resulting in a degree of substitution of 2.04 mmol/g. Incorporation of T-CNFMA in the PEGDA network allowed for independent control of hydrogel stiffness and mesh size by reinforcing the whole hydrogel network as a framework. Consequently, the swelling ratio and shear modulus could be manipulated by controlling the PEGDA/T-CNFMA ratio. Structural analyses revealed that an increase in the T-CNFMA content in the presence of a low amount of PEGDA resulted in a large mesh size with a constant stiffness. The diffusivity test was also consistent with the properties of the hydrogels. This result indicates that the incorporation of T-CNF in hydrogel network is useful to control the physical property of the hydrogel, especially for varying mesh size, regardless of stiffness alteration.

Optimizing Electrodeposition of Polyaniline on Various Woven Steel Mesh Sizes for Enhanced Supercapacitor Performance.

The development of efficient supercapacitors hinges on the innovation of superior electrodes, which are pivotal in augmenting their energy storage capabilities. Supercapacitors, recognized for their high-power density and extended cycle life, play a crucial role as sustainable solutions in addressing energy storage challenges. A fundamental aspect of supercapacitor functionality involves the electrode material, which works in concert with other key components such as the current collector, separator, and electrolyte. This study focuses on evaluating the impact of the current collector material on the performance of symmetric supercapacitors. We investigated the electropolymerization of polyaniline on woven steel mesh current collectors of varying mesh sizes, ranging from 20 to 200 mesh per inch, using assorted deposition conditions. The electrochemically modified woven steel meshes were utilized to construct symmetric supercapacitors. The electrochemical performance of the assembled supercapacitors, configured in a two-electrode system, was investigated using a variety of electrochemical techniques to better understand the kinetics of electrolyte ion migration. Notably, the 20-mesh size, characterized by the fewest pores per inch, demonstrated superior performance with an optimum capacitance of 4730 mF/cm2, an energy density of 317.8 μWh/cm2, and a power density of 400 μW/cm2 at a current density of 1 mA/cm2.

Faecal particle size distribution in relation to forage type and digestibility in horses: preliminary results

The study aimed to explore the connection between horses’ total tract apparent dry matter digestibility (ttaDMD) of various roughages and faecal particle size (FPS), to develop a tool to rank roughage digestibility. Six horses, varying in size and breed, were fed six distinct roughages (four cuts of fescue, perennial ryegrass/clover mix, and straw). Each feeding period lasted 16 days, with a 14-day adaptation phase. Faecal samples underwent wet sieving analysis. Roughage chemical composition was evaluated using NIRs. Faecal and roughage acid insoluble ash content were used to estimate ttaDMD and FPS was determined by wet sieving using a set of 6 sieves of different mesh sizes (S1 to S6; 6.50, 4.50, 2.36, 1.18, 0.6 and 0.15 mm respectively). The effects of roughage ttaDMD on FPS across sieves were analysed using GLM. Linear regressions and correlations were performed between faecal residues on each sieve and mesh sizes of the sieves to create a mathematical tool to rank ttaDMD based on FPS distribution. Increased ttaDMD was associated with larger FPS, with perennial ryegrass/clover mix (ttaDMD 74.44%) and straw (ttaDMD 44.57%) resulting in smaller and larger faecal particles respectively. Correlations were observed between ttaDMD, S1 and S2 (r = 0.639 and 0.668; p ≤ 0.001). The angular coefficient of the linear function between faecal residues on each sieve support the idea to estimate roughages digestibility from FPS (R2 = 0.4153). Consequently, determining faecal residues across sieves of varying mesh sizes could serve as an indirect method for ranking roughages digestibility.

A rapid prediction model for the radiation efficiency of baffled constrained layer damping plate

It’s well-known that constrained layer damping (CLD) can effectively reduce the vibration and radiation noise from the (plate-like or shell-like) thin-walled structures under various of dynamic excitations. As one of the key properties deciding the CLD’s performance, the CLD’s acoustic radiation characteristics has always been a focus of researchers. In this study, an analytical model based on equivalent principle is proposed to predict the acoustic radiation efficiency of the CLD plate. In this model, a laminated CLD plate is equivalent to a single-layer plate and the equivalent stiffness and loss factor are obtained using the strain energy method. The vibration velocity of the plate is calculated using mode-superposition method and the sound pressure on the plate surface is calculated using Rayleigh integral formula. Variable mesh sizes and frequency steps are employed to improve the calculation efficiency. The difference between the base and CLD plates in sound radiation characteristics is investigated using this model. The results indicate that CLD involving a damping layer with a low Young’s modulus can mitigate more vibration at low frequencies. A higher Young’s modulus of the damping layer results in a higher radiation efficiency of the CLD plate between the fundamental and critical frequencies. By increasing the loss factor, the spatially averaged mean square velocity would decrease, more modes would contribute to the response, and the CLD plate can consequently achieve a higher radiation efficiency below the critical frequency. Moreover, the simplified formulae for the average radiation efficiency of the CLD plate is developed to achieve the rapid calculation. Its accuracy is then validated by comparing the results to the more comprehensive model.

ANALYSIS OF PRODUCTION FACTORS FOR GILLNET FISHING GEAR AT THE TECHNICAL IMPLEMENTATION UNIT (UPT) OF THE FISHERY PORT OF RIAU PROVINCE

Dumai City relies entirely on marine waters for its fisheries production, with gillnets being a predominant fishing gear among local fishermen. Gillnets, characterized by their rectangular shape with varying mesh sizes, utilize floats and weights. This study aimed to identify the factors influencing gillnet catches in Dumai City. Results from simultaneous testing revealed that all production factors significantly impact catch quantities. Through multiple linear regression analysis, it was determined which factors exerted positive and negative effects. The regression equation, Y = 0.108 – 0.183 X1 – 0.411 X2 – 0.345 X3 + 0.173 X4 + 0.116 X5 + 0.451 X6 + 0.181 X7 – 0.106 X8 + 0.223 X9, elucidated these relationships. The cumulative effect of production factors on catches amounted to 64.20%. This study provides valuable insights into optimizing gillnet fishing practices in Dumai City's marine environment.

Effect of Surface Structure on the Sensitivity of Fluorescence-Enhanced Si Photodiodes for Ultraviolet C Light Measurement

This study aims to significantly enhance the sensitivity of a fluorescence-enhanced Si photodiode (FE-PD) to ultraviolet C-ray (UVC) light by optimizing the three-dimensional surface shape of the phosphor attached to the Si-PD, thereby increasing the UVC detection sensitivity. In the sensitivity-enhanced FE-PD, the surface of the red fluorescent acrylic resin phosphor affixed to the Si-PD was carved with a stripe and grid at varying depths, and triangular roofs and square pyramids at various angles. The effects of roughening the phosphor surfaces with diamond abrasives of varying mesh sizes—ranging from #180 to #3000—were comparatively evaluated against those with flat, mirror-like surfaces. As observed, the UVC light sensitivity of the FE-PD using a surface-carved triangular roofs and square pyramids at angle of 70° exhibited significant improvements compared to the Si-PD with both non-modified and mirror-polished phosphors. Thus, the FE-PD with a surface-modified phosphor is a promising candidate for UVC light sensor.

Study on Aeolian Sand-Box Backfill Geomechanical Characteristics and Overlying Strata Control Effects

The aeolian sand-box backfilling method proves effective for environmentally friendly coal extraction in northwestern regions, including Xinjiang. This study investigated the geomechanical characteristics of aeolian sand-box backfill material and its control effects on overlying strata through indoor experiments, mechanical analysis, and numerical simulations. Uniaxial compression tests on models with varying mesh sizes, wire diameters, and dimensions revealed that larger mesh sizes and wire diameters increased the bearing capacity of the aeolian sand-box backfill material, while increasing dimensions had the opposite effect. A mechanical analysis of the metal mesh box deformation produced equations describing its restraining force. Subsequent experiments and simulations on models of different dimensions consistently demonstrated the material’s mechanical properties, with stress-displacement curves closely aligned. 3DEC5.2 software simulations highlighted the effectiveness of aeolian sand-box backfill material in controlling displacement and stress variations in goaf areas. Notably, smaller-sized backfill material exhibited a more pronounced impact on controlling overlying strata displacement and stress development.

Theoretical Error Analysis of Hybrid Finite Difference–Asymptotic Interpolation Method for Non-Newtonian Fluid Flow

In this paper, we utilized a hybrid method for the unsteady flow of the non-Newtonian third-grade fluid that combines the finite difference with the asymptotic interpolation method. This hybrid method is used to satisfy the semiunbound domain condition of the fluid flow’s length approaching infinity. The primary issue with this research is how much of the hybrid approach’s error may be accepted to guarantee that the method is significant. This paper discussed theoretical error analysis for numerical solutions, including the range and norm of error. The perturbation method’s concept is used to assess the hybrid method’s error. It is discovered that the hybrid approach’s relative error norm is lower than that of the finite difference method. In terms of the error standard, the hybrid approach is more consistent. Error analysis is performed to check for the accuracy as well as the platform for variable mesh size finite difference method in the future research.

A New Multi - Block Super Class of BDF for Integrating First Order Stiff IVP of ODEs

A new multi-block super class of backward differentiation formula for integrating first order stiff IVPs with a variable mesh size strategy is derived. The proposed scheme approximate two solution values at a time per integration step. The stability properties are achieved by varying the mesh size ratio in the formula to generate more zero stable and A-Stable schemes, capable of solving stiff IVPs of ODEs. Approximates result from the system of stiff ODE problems considered are found to favorably validate the new method in terms of accuracy of the scale error and less executional time in respect to the two methods compared in the study. Hence, the proposed scheme can be used for solving for stiff IVPs of ODEs.

Towards quantifying microbial dispersal in the environment.

Towards quantifying microbial dispersal in the environment.

A newly treated boundary conditions to enhance accuracy of finite element analysis for orifice-type aerostatic bearings

Although numerical approaches have been extensively employed for solving the Reynolds equation in order to predict the performance of air bearings, we found inappropriate boundary settings can cause significant numerical errors if the grid-dependent condition is ignored. The current scrutiny is focused on crucial procedures for adopting the finite element method to assess the performance of orifice-type aerostatic bearings. To this end, numerical models for a single orifice-type are established and then checked by varying mesh sizes, mesh types, and boundary conditions (BCs). The obtained results reveal that those numerical models with a single-source node are grid-dependent, and the relative error is so large that the results are not credible compared with the analytical solution and becomes worse with denser meshes. This peculiar phenomenon can be mathematically interpreted by a one-dimension finite difference model calculated manually and auxiliary sources have proved to be an effective technique to reduce single-source numerical error to an acceptable level. Additionally, a physical explanation is given based on engineering systems modeling. By this view, rules of setting high pressure on the edge of recess are proposed and three types of grid-independent BC settings are proposed. Stiffness test experiments based on manufacturing a rotary table adopting multi-orifice aerostatic thrust bearings are further carried out to validate these numerical models, and the discrepancy between measured and calculated stiffness is reported to be lower than 5%.

Uncertainty and Consistency Assessment in Multiple Microplastic Observation Datasets in the Baltic Sea

This paper aims to quantify data uncertainties in marine microplastic measurements, including spatiotemporal sampling error and sample volume estimation error, identify impacts of varying mesh sizes, sampling and analysis methods, and evaluate consistency in multiple microplastic observation datasets. Twenty-seven datasets on surface marine microplastics with particle size >100 µm in the Baltic Sea are compiled. Results show that the trawl datasets have a spatiotemporal sampling error of 25% for microlitter concentration, 36% for microplastic fiber concentrations and 40-56% for microplastic particle concentration. By taking surface currents and wave-induced Stokes drift into account, the sample volume of the trawl measurements is corrected, leading to a mean microplastic concentration correction of 12%. The differences of microplastic concentration between datasets with varying mesh sizes from 100 – 500 µm are not statistically significant. Analysis methods, however, can lead to significant differences in microplastic datasets. The dataset consistency is further examined among the three dataset categories using trawl, pump and bulk sampling techniques. It is found that an individual dataset is often self-consistent. Most of the datasets within one monitoring category are more consistent than those from different categories. More than 70% of the datasets within individual categories are consistent, which have mean microplastic concentration significantly smaller than the rest of the datasets. Significant inconsistencies are identified between different data categories. Six out of eight highest relative standard deviations are found in the pump and bulk datasets. The median value of the mean microplastic concentration from the 10 pump datasets is about 4.5 times as much as that of the 14 trawl datasets, both for fiber and non-fiber particles. Significant differences are also identified on microplastic fiber fraction in different dataset categories. Two thirds of the 13 bulk and pump datasets have a microplastic fiber fraction >85% while the 14 trawl datasets show much lower microplastic fiber fractions between 45-70%. In addition, the particle collection efficiency, potential leakage of particles with irregular shapes, clogging, the false zero samples and related lower limit of the detectable microplastic concentration for given sampling methods and water environment, are also discussed.

Experimental evaluation of a solar-driven adsorption desalination system using solid adsorbent of silica gel and hydrogel.

Nowadays, the world is facing a shortage of fresh water. Utilizing adsorbent materials to adsorb air moisture is a suitable method for producing freshwater, especially combining the adsorption desalination system with solar energy devices such as solar collectors. The low temperature of solar collectors has caused some water to remain in the adsorbents in the desorption process and has reduced the possibility of using these systems. In this research, for the first time, an evacuated tube collector (ETC) is used as an adsorbent bed so that the temperature of the desorption process reaches higher values and as a result, more fresh water is expected to produced. In this study, two adsorption desalination systems (ADS) are experimentally investigated. In the first system, a laboratory experimental setup using silica gel and hydrogel adsorbents is used to investigate freshwater production using each of the two adsorbents. The effect of different parameters such as variable adsorption and desorption time, variable temperature and humidity of inlet air, and variable adsorbent mesh sizes on the desalination process is evaluated. Then, in the second system, an innovative configuration of the solar-driven adsorption desalination system with an ETC full of silica gel is studied. In the laboratory experimental setup, the maximum amount of water produced by silica gel is 0.36 L/kg and by hydrogel is 0.58 L/kg. In the solar-driven adsorption desalination system, the largest amount of accumulated water production, daily efficiency, and cost per liter (CPL) of produced water are 1.518kg/m2 day, 11.25%, and 0.0699 $/L, respectively. Therefore, this new configuration for an adsorption desalination system seems feasible.

Development of ductile fracture modelling approach in ship impact simulations

A fracture modelling approach is developed to provide predictions in shell element simulations. MSSRT criterion is employed and combined with the modified BWH criterion in the fracture scaling framework to mitigate the mesh size sensitivity. Meanwhile, the effect of bending loads on the fracture prediction is considered by introducing the deformation mode indicator in the model. The predictive capability of the developed fracture model is evaluated by simulating penetration tests of the double hull structure. Reliable predictions of fracture initiation and propagation are yielded with varying mesh sizes. Typical failed elements in the double hull FE model are analyzed, with emphasis given on the evolution of damage for different through-thickness integration points. Based on this, the effects of bending loads on the fracture prediction are discussed in detail. It is demonstrated that the present fracture model can capture the fracture behavior of shell elements with sufficient engineering accuracy. This is especially relevant in the evaluation of ship impact analysis where limited knowledge of the material behavior is available. Although bending is not the dominated deformation mode in the double hull structure, the inclusion of the bending effects in the fracture model tends to provide more consistent prediction results.

Mechanical Disintegration and Particle Size Sieving of Chondrus crispus (Irish Moss) Gametophytes and Their Effect on Carrageenan and Phycoerythrin Extraction.

To better understand the migration properties of hybrid carrageenan from the seaweed tissue during carrageenan extraction, the effect of increasing the seaweed surface area by the mechanical disintegration of gametophyte Chondrus crispus chips was studied under various temperature and time extraction conditions. Dried Chondrus crispus seaweed chips were milled by a rotor beater mill and classified into eight different size fractions by sieving with varying mesh sizes from 50 to 2000 μm. During extraction at 22 °C, the red color of the filtrate increased significantly with the decreasing particle size of the fraction, correlating with the increasing phycoerythrin concentration (from 0.26 mg PE/g dry seaweed in the >2000 μm size fraction to 2.30 mg PE/g dry seaweed in the <50 μm size fraction). On the other hand, under the same extraction conditions, only a small increase in carrageenan precipitate was obtained with the decreasing size fractions (from no recovery in the >2000 μm size fraction to 2.1 ± 0.1 g/kg filtrate in the <50 μm size fraction). This yield was significantly lower than the ones from extractions at 45 °C (5.4 ± 0.1 g/kg) or at 90 °C (9.9 ± 2.1 g/kg) for the same particle size and time conditions. It could be concluded that hybrid carrageenan extraction is not surface area dependent, while phycoerythrin is. Therefore, it seems that phycoerythrin and carrageenan extraction follow different mechanisms. This creates potential for the selective extraction of each of those two compounds.

Role of soil fauna to litter decomposition in pine stands under Atlantic Forest biome

Litter production and its decomposition play an important role in the terrestrial carbon cycle and soil quality, being a crucial process involved in ecosystem productivity and functioning. Understanding this process under pine commercial stands or pine invasions is crucial to design forest management or ecosystems restoration. We conducted a study in a commercial pine plantation (Pinus taeda L.) under Atlantic Forest biome to investigate (1) the contribution of soil fauna to pine litter mass loss; (2) the litter fauna feeding activity within seasons. Litter bags with pine needles (5 g dry weight) were prepared as exclusion treatments for different sized soil fauna by varying mesh size (2 mm and 0.06 mm). Litter bags were removed after 60, 120, 180, 240, 300, and 365 days to estimate the decomposition rates. Bait lamina sticks were exposed seasonally and horizontally in soil surface to determine the fauna feeding activity on litter. We found: (1) no differences in litter mass loss and decomposition rate when soil macrofauna and most of the mesofauna were excluded; (2) feeding activity of litter organisms was higher in the summer, probably stimulated by a combination of high temperature and rainfall. In commercial pine stands, we can conclude that the nutrient cycling is slower than in natural areas, related to litter traits, as described in the scientific literature. Our results indicated that soil macro and mesofauna play a low role in the pine litter decomposition, where the organic material decomposition is more related to microorganism’s activity.

Diversity and Some Biological Aspects of Fishes in Lake Maybahr, Albuko Woreda, Ethiopia

Because fishes live in less-accessible habitats, their remarkable diversity is rarely appreciated. The fishery sector is growing rapidly worldwide with the intention of improving the livelihood in developing nations. Therefore, conservation and management of aquatic resources become eminent. Morphometric measurements of fishes are important tools in fish biology and fisheries assessment and conservation. Ethiopia is one of the developing countries with rich water resources. Although there are plenty of water bodies in the country, they are less explored for their ichthyofaunal documentation. Therefore, this study aimed to explore the diversity and some biological aspects of fishes in Lake Maybahr. The fish sample was collected from selected sampling sites using gill nets with varying mesh sizes. Fish identification was done in the field using relevant taxonomic keys. After identification, the total length (TL) and total weight (TW) of the specimens were measured to the nearest 0.1 cm and 0.1 g, respectively. After measurement, the samples were labeled and preserved in a 10% formalin solution. Two fish species were documented in the study area. The length-weight relationships indicated that both species (C. carpio and O. niloticus) exhibited allometric growth during the wet season. But C. carpio demonstrated an isometric growth in the dry season. The diversity index (H’ = 0.69) revealed that fish diversity in the current study is far less than the result reported in the other studies. The evenness index (J’ = 0.99) showed that each species is fairly represented by a number of individuals. The correlation coefficient value of length and weight parameters is statistically significant at a 1% significance level (s, R2 = 0.85). The mean FCF revealed that both fish species are in good health. Further study on local people’s perception, initiating fishing activities, and organizing and providing training to youth is recommended.

Dispersion and Stability Analysis for TLM Unstructured Block Meshing

The insatiable demand to optimize and engineer new functionalities in electromagnetic devices has risen their geometrical complexity to unprecedented levels. This usually results in computationally multiscale problems with some tiny components of great importance to the overall behavior of these devices. Block meshing is a powerful technique for treating such problems. The usage of variable mesh size is adaptable for adequately representing the geometrical details without exhausting the computational resources with a uniform fine grid in the entire computational domain. In addition, block meshing allows the use of cubic cells only for which time step in maximum and velocity error is minimal in each subregion. In this article, we present a mathematical formulation for stability and dispersion analysis when using block meshing in the transmission-line matrix (TLM) method. These relations permit us to compute the maximum mesh size and time step that guarantee a tolerable level of numerical dispersion, hence minimizing the computational expenditures. Moreover, we study the case of adopting the local time step and demonstrate the origins of the instability that may appear in this case. Finally, some numerical experiments are presented to show the advantages of the proposed approach when using TLM block meshing. A similar procedure can be used for FDTD or FIT with block meshing.

Heterogeneous material mapping methods for patient-specific finite element models of pelvic trabecular bone: A convergence study

Patient-specific finite element (FE) models of bone require the assignment of heterogeneous material properties extracted from the subject's computed tomography (CT) images. Though node-based (NB) and element-based (EB) material mapping methods (MMMs) have been proposed, the sensitivity and convergence of FE models to MMM for varying mesh sizes are not well understood. In this work, CT-derived and synthetic bone material data were used to evaluate the effect of MMM on results from FE analyses. Pelvic trabecular bone data was extracted from CT images of six subjects, while synthetic data were created to resemble trabecular bone properties. The numerical convergence of FE bone models using different MMMs were evaluated for strain energy, von-Mises stress, and strain. NB and EB MMMs both demonstrated good convergence regarding total strain energy, with the EB method having a slight edge over the NB. However, at the local level (e.g., maximum stress and strain), FE results were sensitive to the field type, MMM, and the FE mesh size. The EB method exhibited superior performance in finer meshes relative to the voxel size. The NB method converged better than did the EB method for coarser meshes. These findings may lead to higher-fidelity patient-specific FE bone models.

Reproductive biology of hampala barb (Hampala macrolepidota Kuhl & Van Hasselt 1823) in Ranau Lake, Indonesia

One of the economically valuable consumption fish in Ranau Lake is the hampala barb (Hampala macrolepidota). Hampala barb is the top predator in Ranau Lake. The fish population is still quite a lot, but it is starting to decline. This study aimed to determine the reproductive biology of hampala barb in Ranau Lake. Ranau Lake is located in South Sumatra Province and Lampung Province, Indonesia. The research was conducted by the inventory survey method and laboratory analysis. Fish samples were obtained from fisher’s catch, where the fish were caught using gill nets with varying mesh sizes and harpoon. The fish were measured for length body and total weight. Then surgery was performed to determine their reproductive biological characteristics (sex, size of first gonad maturity, gonad maturity stage, Gonad Somatic Index, fecundity, and egg diameter). The results showed that the hampala barb in Ranau Lake laid the eggs throughout the year with a sex ratio of 1: 1, the size of the first stage of gonad maturity of male and female were 15.38 cm and 19.21 cm, fecundity between 17,406-63,793 eggs, and egg diameter between 0.8-1.9 mm. This reproductive biology information can be used for the management of hampala barb in Ranau Lake.