Fiber Elements Research Articles

Modeling amplified arbitrary filtered heterodyne microwave photonic links.

We report an end-to-end analytic model for the computation of the figures of nerit (FOMs) of arbitrarily filtered and amplified heterodyne coherent microwave photonics (MWP) links. It is useful for evaluating the performance of complex systems where the final stage is employed for up/down-converting the radio frequency (RF) signal. We apply the model to a specific case of complex system representing the front-haul segment in a 5G link between the central office and the base station. The model can be however applied to a wider range of cases combining fiber and photonic chip elements and thus is expected to provide a useful and fast tool to analyze them in the design stage.

Benchmark Numerical Model for Progressive Collapse Analysis of RC Beam-Column Sub-Assemblages

The pertinence of the fiber element approach to enable thorough numerical investigation on the potential for progressive collapse of reinforced concrete (RC) frame structures owing to interior column exclusion is examined using twenty-nine RC sub-assemblages with five different test setups and three different test scales. A qualitative examination of the results reveals a good agreement between the test results and the outcomes of the fiber-element-based numerical model using the finite element package SeismoStruct. Moreover, minor discrepancies between the test and numerical data demonstrate the capability of the fiber-element-based model to accurately simulate the behavior of RC elements with various boundary conditions and scales under the context of progressive collapse. Given the costly nature of experimental research, test errors, and the lengthy testing process, the proposed numerical model based on the fiber element approach can be considered a viable option for analyzing structures under progressive collapse due to the interior column exclusion scenario. Engineers and researchers can use the conclusions and comments highlighted in the study as a guide to create accurate models for the analysis of RC structures subjected to progressive collapse.

Membrane fiber element for reinforced concrete walls – the benefits of macro and micro modeling approaches

A novel element that mixes the formulation and versatility of microscopic models, and the mesh refinement of macroscopic models, was developed to predict the nonlinear response of reinforced concrete walls. The element, named as Membrane Fiber Element (MEFI), is described by four nodes, each containing three degrees of freedom (DOFs), two translations, and one in-plane rotation (drilling) DOF, which incorporates a blended interpolation function for the displacements over the element. The element formulation accommodates the quadrature points and weights of the classical finite element formulation of membrane elements to resemble strips (fibers), similarly to macroscopic elements. In this modeling approach, a RC panel element that follows a fixed-angle approach was used. The element was validated against five RC wall specimen tests with rectangular cross-sections and different aspect ratios reported in the literature. Also, the element was validated for walls with discontinuities using data from an experimental program of walls with openings. Comparisons of model predictions and experimental results, reveal that the MEFI element is reliable to predict the nonlinear response of reinforced concrete walls with different aspect ratios and properties, requiring less mesh refinement, and therefore less running time, for an accurate response estimation compared to finite element models.

Buckling resistance of steel fibre-reinforced concrete encased steel composite columns

Six steel fibre reinforced high strength concrete (SFRHSC) encased steel columns were tested to investigate their structural performance without the need of conventional longitudinal steel reinforcements and stirrups. The SFRHSC encased steel composite columns were tested until failure under eccentric compression load to determine their buckling resistance including the compression and moment strength interaction behaviour. Furthermore, two composite beams with similar cross-section were subject to four-point load to obtain the load-deflection behaviour and ultimate moment resistance. The experimental results showed that, without the presence of longitudinal steel bar reinforcements, the steel fibre-reinforced composite columns exhibited ductile behaviour and showed no evidence of debonding or early cover spalling. Test evidence showed that the hooked-end steel fibres were able to bridge the growing cracks effectively. Two analytical approaches were proposed to predict the compression and moment resistances of the tested columns. The first model was based on the fibre element analysis, while the second model provided a simplified analytical prediction. Both the models were developed accounting for second-order effects in slender columns. The models were able to predict the test results with reasonable accuracy. The test results also fitted well with the predicted axial force–moment strength interaction curves.

Beverages and Desserts With Therapeutic and Prophylactic Properties Based on Alginate-Containing Biogel From Laminaria -- ``Vitalgar Cardio''

In this research, recipes were developed for beverages and desserts based on ”Vitalgar Cardio”, abiogelthat contains alginate, has therapeutic and prophylactic properties, and was produced from laminaria at the SPC ”Vita-Li” LLC. ”Vitalgar Cardio”, in its liquid form, as well as desserts based on it, is a source of soluble dietary fiber (alginates) and chemical elements such as potassium, magnesium and iodine, and is an adsorbent of various toxins, including radionuclides and heavy metals. The developed products have traditional appeal, with a focus on healthy nutrition, which is currently being promoted among the population.
 Keywords: Lamibaria, Alginate, Fucoidan

Numerical investigations of circular double-skin steel tubular slender beam-columns filled with ultra-high-strength concrete

The use of ultra-high-strength concrete in double-skin concrete-filled steel tubular (DCFST) composite columns has received considerable attention in recent years. However, no numerical study on the behavior of eccentrically loaded circular DCFST slender beam-columns made of ultra-high-strength concrete has been reported. This paper proposes computational modeling procedures for accurately predicting the axial load–deflection responses and axial load-moment interaction diagrams of circular DCFST slender beam-columns filled with ultra-high-strength concrete when subjected to the combined action of bending and axial compression. The computational procedures based on the fiber element methodology incorporate the effects of concrete confinement, second-order and initial geometric imperfection on the behavior of DCFST slender beam-columns. The enhanced King-Werner’s algorithm is implemented in the fiber-based procedures to solve the nonlinear moment equilibrium equation. The accuracy of the present model is verified with experimental results published in the literature and finite element analysis results. The numerical results reveal that the confined concrete model can capture the response of ultra-high-strength concrete with a sudden drop after reaching the peak load and the ductility in the softening branch. The significance of several influencing factors on the structural behavior is investigated in the comprehensive parametric study including 154 specimens with a wide range of column geometric and material properties. The design of circular DCFST slender beam-columns with ultra-high-strength concrete in accordance with Eurocode 4 is discussed. The artificial neural network (ANN) model is developed to propose new empirical formulas for evaluating the member resistance of DCFST slender beam-columns. The proposed equations give accurate and reliable predictions of the column’s resistance and can be employed in practical design.

Studies on Tracheary Element of Several Native Cycad Species in Australia and Two American Plants

Studies on Tracheary Element of Several Native Cycad Species in Australia and Two American Plants

UV laser processing in reparison task of monolotithic laminate of carbon fibre elements. Influence of processing direction

In aeronautical sector, the step of removing damaged fabrics included in the process of reparison of carbon fibre elements is performed via manual grinding.  This procces is few automatable and shows high level of dificulty in depth control of removed material. Owing to the trend to procceses automation, different automatable technologies are being studied as alternatives that enable to obtaing higher control of this process. This work studies the use of an UV laser system to perform this task. This technologies led to a salective and controlled revomal of fabrics by the control of processing paramenters. Firstly, values of power, processing speed and frequency have been optimised in order to obtain an acceptable rermoved material amount to time ratio. Furthermore, the influence of fibre relative orientation with respect to processing direction on the amount of removed material has been studied. For that purpose, unidirectional tape samples have been laser processed with different processing direction, and the amount of removed material for all of them has been measured. Once optimized the processing direction, the number of shadows required to remove one entire fabric has been determined. Processing conditions that enable to remove selectivley and controlled fabrics of composite material have been determined. This would allow to automate the process of removing fabrics included in bonded breparison of elements of carbon fibre.

Research Advance on Application of Microbial Fermented Fodder in Broilers Production: A Short Review

Recently, interest in animal production and poultry production in particular has increased, because poultry meat and eggs and their products are more widely consumed than other products. Human health is also considered one of the priorities. Nowadays, the fermentation industry has become very popular due to its great benefits in the pharmaceutical industry, the improvement of foodstuffs and the animal feed industry and its improvement. Moreover, microbial fermentation can enhance the content and digestibility of nutrients in nontraditional diets while decreasing the quantity of crude fiber and anti-nutritional elements such as tannins. The functional components (organic acids, bioactive peptides, lactic acid bacteria) found in microbial fermented feed can increase meat production in cattle, pigs, and sheep, and broiler productivity, carcass quality, intestinal health, immunological function, and so on. This paper examines the application study of microbial fermented feed in broiler production and serves as a resource for microbial fermented feed promotion and use in broiler production.

Multiple indicators metrological analysis for 5 kinds of tea produced in Yunnan, China

Five kinds of tea, including camphor-scented palace tea, fossil glutinous rice tea, old tree white tea, Brown Mountain ancient tree tea, and pure Banzhang tea, from Yunnan Province, China, were selected as the samples for analysis. The combustion heat, differential thermal-thermogravimetric, fat content, crude fiber content, ash content, and trace element content data of the teas we selected were determined, and quality evaluation and classification were carried out by the stoichiometric method from the perspective of food nutrition. In this paper, according to the combustion heat, differential thermal-thermogravimetric, fat content, crude fiber, ash content, and trace element content data of the teas we selected, systematic multi-index comprehensive evaluation systems were constructed through gray pattern recognition, factor analysis, the entropy method and entropy cluster analysis. The multi-index comprehensive evaluation system established in this study provides a new concept for the quantitative control of the quality of tea, a powerful method for research on the large-scale development and classification of tea and basic support for the selection of raw tea materials and the application of a quantitative control mode for assessing the contributions of multi-index ingredients to tea quality.

Rutting prediction of hot mix asphalt mixtures reinforced by ceramic fibers

One of the most severe problems with flexible asphalt pavements is permanent deformation in the form of rutting. Accordingly, the practice of adding fiber elements to asphalt mix to improve performance under dynamic loading has grown significantly in order to prevent rutting distress and ensure a safe and long-lasting road surface. This paper explores the effects of a combination of ceramic fiber (CF), a low-cost, easily available mineral fiber, and thermal insulator fiber reinforced to enhance the Marshall properties and increase the rutting resistance of asphalt mixes at high temperatures. Asphalt mixtures with 0%, 0.75%, 1.5%, and 2.25% CF content were prepared, and Marshall stability and wheel tracking tests were employed to study the effect of added CF on asphalt mixture performance. Scanning electron microscopy (SEM) and field emission scanning electron microscopy (FESEM) were also used to investigate the morphologies of CF and reinforced asphalt mixtures and to identify the mechanism of improvement .According to the study results, the ideal ceramic fiber content was 1.5%, which yielded an improve in Marshall stability and reduced rut depth by 22.05% and 27.71% at temperatures of 50°C and 60°C, respectively, when compared to asphalt mixtures without CF. Microscopic analyses clearly revealed the surface properties, particle diameter size, and fiber distribution of the reinforced mixture, including the network structure and strength mechanism, which improved the performance of the asphalt mixture by forming a three-dimensional network.

UV laser surace activation in co-bonding of CFRP elements. Comparison with other certified methods

There is an increasing trend towards the substitution of mechanical joining by adhesive bonding in carbon fibre elements (CFRP) in aeronautical sector. However, it is mandatory to perform a previous step of surface preparation in order to obtain the best adhesive properties to the surface. There are some certified superficial preparation methods by the aeronautical sector, being shot peening, grinding and peel-ply the most used ones. All of them have the disadvantage of not being automatable. Hence, new potentially automatable methods for surface activation are being studied. In this work it has been studied the use of UV laser radiation as a surface activation method previous to adhesive bonding, and its behaviour has been compared to peel-ply activated samples. To this end, an advanced surface characterization has been performed, by means of surface free energy determination, surface chemical composition determination by XPS measurement, surface roughness and morphology observation with SEM. Mode I fracture toughness test have been performed for all surface activation methods. The obtained results show that adhesive bonding of UV laser treated samples have mode I fracture toughness comparable values to those obtained for peel-ply and peel-ply plus grinding samples. Furthermore, all the failure modes observed are accepted by the sector normative. This makes that UV laser surface preparation could be considered as an alternative for certified surface method of CFRPs.

Mesoscopic modelling of UHPCC material under dynamic tensile loadings

This paper presents a new 3D mesoscopic model of ultra-high performance cement-based composite (UHPCC) to investigate its dynamic tensile behavior. In this model, the UHPCC is regarded as a two-phase material composed of cementitious matrix and randomly distributed fibers. The model is established using the commercial software LS-DYNA and involves generating the randomly distributed fiber elements with considerations of diameter, length, orientation and volume fraction, and then fully constraining them with the matrix. In particular, to capture the slipping effect between fibers and matrix that has a strong influence on the dynamic tensile behavior, the fibers are modelled by a fictitious material represented by the load-slip relation. The strain-rate effect of slipping force neglected in most of previous studies is considered by calibrating constitutive parameters of the fictitious material under different strain-rates based on the single fiber pullout tests. Finally, the 3D mesoscopic model is validated against three sets of tension-dominated experiments covered a wide range of loading intensity. Numerical predictions demonstrate that strain-rate effect of slipping force must be considered, and the neglect of it may lead to a great underestimation of the dynamic tensile strength of UHPCC material and would unavoidably underestimate the blast resistance of UHPCC components.

Fiber Based Modeling Strategies of RC Columns

Although experimental studies have proven as the most effective method, its high cost has provoked researchers to seek alternative approaches. The increase in computational power in the 21st century provides the opportunity to numerically model experimental studies with various programs. This study examines the comparison of force-based element and displacement-based element in columns using nonlinear fiber elements. Within the scope of the study, OpenSees program is employed for columns selected from the PEER (Structural Performance Database) site. Physical regularization technique is applied to the elements while considering the plastic hinge length of the columns. The aim is to compare the employment of the FB element and DB elements in RC columns in terms of number of elements and integration points, to simulate the global behavior of the columns numerically, and to optimize the parameters that affect the results.

RESIN FLOW SIMULATION DURING THE RTM METHOD OF COMPOSITES PRODUCTION

Processes of plastic injection molding are often under analyzes in industry and science. Many of these considerations apply to epoxy resins with additional reinforcement, often with glass or carbon fiber inside the closed mould. The simulations of injection molding processes in the production of composite elements is not as common, as thermoplasts. Hence the idea to carry out the work described in this article. The RTM (Resin Transfer Molding) method is dedicated to serial production with the possibility of producing visual carbon fiber elements for aesthetic reasons. Simulations can help to better refine the products. This allows to take appropriate precautions and solve many issues before implementation. The article presents possible situations that could occur in real conditions. Various shapes models were prepared as basis of the numerical calculations. The analyses highlighting the possible issues were performed. The influence of resin pressure and flow rate on the final product was also considered. The aim was to present the characteristic phenomena and their causes that often occur in reality to technologists working with the RTM. Conclusions related to the work carried out are included. Based on the analyzes and conclusions drawn, it is possible to improve the quality of production processes.

Mechanistic model for prediction of the residual tensile strength of FRP wires

In-service cables made of fiber-reinforced polymer (FRP) wires experience repeated loading during their service life, which gradually degrades their load-carrying capacity. This paper proposes a mechanistic model to predict the residual tensile strength of the FRP wire, based on the state of damage inside the FRP wire as a function of the loading cycle. The mechanistic residual strength model developed here is an extension of the progressive fatigue damage model (PFDM) proposed recently by the authors. The main failure mode in the FRP wire in the PFDM is fiber breaks, allowing for the state of damage in the FRP wire to be determined for a specified maximum fatigue stress level and number of cycles. These results are then used as the input to calculate the residual strength of the FRP wire. Results indicate that the model can predict the residual strength of FRP wires well compared with the experimental data that has appeared in the literature. The proposed model is shown to provide a better understanding of the influence of the fatigue loading conditions on the residual tensile behavior of FRP wires, specifically, the effect on the residual stress-strain response, the kinetics of fiber element breaks, and the critical damage cluster. Moreover, the proposed model allows validation of the adequacy of safety factors typically adopted by designers to consider the degradation in strength of FRP cables, which is critical for the successful design and realizing the full potential of FRP cables.

Distinct Aging-Vulnerable and -Resilient Trajectories of Specific Motor Circuit Functions in Oxidation- and Temperature-Stressed Drosophila.

In Drosophila, molecular pathways affecting longevity have been extensively studied. However, corresponding neurophysiological changes underlying aging-related functional and behavioral deteriorations remain to be fully explored. We examined different motor circuits in Drosophila across the life span and uncovered distinctive age-resilient and age-vulnerable trajectories in their established functional properties. In the giant fiber (GF) and downstream circuit elements responsible for the jump-and-flight escape reflex, we observed relatively mild deterioration toward the end of the life span. In contrast, more substantial age-dependent modifications were seen in the plasticity of GF afferent processing, specifically in use dependence and habituation properties. In addition, there were profound changes in different afferent circuits that drive flight motoneuron activities, including flight pattern generation and seizure spike discharges evoked by electroconvulsive stimulation. Importantly, in high-temperature (HT)-reared flies (29°C), the general trends in these age-dependent trajectories were largely maintained, albeit over a compressed time scale, lending support for the common practice of HT rearing for expediting Drosophila aging studies. We discovered that shortened life spans in Cu/Zn superoxide dismutase (Sod) mutant flies were accompanied by altered aging trajectories in motor circuit properties distinct from those in HT-reared flies, highlighting differential effects of oxidative versus temperature stressors. This work helps to identify several age-vulnerable neurophysiological parameters that may serve as quantitative indicators for assessing genetic and environmental influences on aging progression in Drosophila.

Use of Clerodendrum volubile in wheat bread: impact on antioxidant, proximate, minerals and sensory properties

Abstract This study is designed to evaluate the effect of wheat flour substitution with Clerodendrum volubile at different level (1, 3, 5 and 10%) on antioxidant, proximate, mineral and sensory acceptability of wheat bread. The wheat flour was substituted with CVLP at different level (1, 3, 5, and 10%) in the baking of the wheat bread. The inclusion of CVLP led to significant (p < 0.05) and dose dependent increases in the polyphenol contents and antioxidant properties of the CVLP-substituted bread. Also, there were significant (p < 0.05) increments in the crude fibre, crude ash and many mineral elements of the CVLP-substituted breads. Antinutrient (tannins and oxalate) contents of the wheat bread substituted with 10% CVLP were significantly higher (p < 0.05) than the wheat bread. Consumer acceptability of the substituted breads showed that wheat bread with 5% CVLP inclusion has the best acceptance. Therefore, 5% CVLP inclusion is recommended as a suitable level in the bread making.

DIETARY GUIDELINES FOR PROTECTION OF THE OCCUPATIONAL HEALTH OF WORKERS IN FORESTRY

Introduction: Healthy and safe working conditions in the Bulgarian forest economy are associated with a lower incidence of labor abuses and occupational diseases among forest workers. Strategic management in this area includes actions to improve the working environment, part of which is the organization of pre-occupational nutrition. Purpose of the study is to support the occupational health of forest workers with specific dietary guidelines. Methods: The object of the study is 105 workers employed in the forestry of Northern Bulgaria. A documentary method was used - a study of the medical documentation from preventive examinations conducted in the period from 2015 to 2019. The results were analyzed with statistical software SPSS v.20. Results: Dietary recommendations in forestry aim to reduce the occupational health risk from contact with biological hazards, cold and hot microclimate, noise, dust and forced working posture. Dietary guidelines include adequate hydration, recommended eating frequency with a mandatory snacks, consumption of animal foods, fruits and vegetables, which increase the intake of essential amino acids, dietary fiber, vitamins (A, C, B1, B2, B6,), calcium, magnesium and trace elements, limiting the intake of saturated fatty acids and sodium, provision of dining facilities, clean food and clean drinking water. The training of forest workers to regulate energy intake is also being discussed. Conclusion: The implementation of dietary recommendations based on leading occupational hazards in forestry will help to protect occupational health and safety at work.

The impact of nutrition on the development and progression of peripheral artery disease: A systematic review

This systematic review sought to identify and summarize existing evidence for the impact of nutrition on the development, progression, and outcomes of peripheral artery disease (PAD). We performed a systematic literature search of available studies published between January 1974 and December 2019. Randomized controlled trials (RCT), observational studies, and cross-sectional studies reporting either the primary or secondary prevention of PAD with nutritional intake were included. The quality assessment was performed for the RCTs, without pooling a meta-risk estimate. Among a total of 8502 records screened, 186 full texts were assessed for eligibility, and 82 studies (30% RCT) were analyzed. The nutrients were structured in fruits, vegetables and antioxidants, fats and oils, dietary fiber, meat, proteins, vitamins and trace elements, and diets and lifestyle. The findings of the current systematic review indicate that the Mediterranean diet, nuts, and polyunsaturated fat are associated with a lower incidence of PAD and saturated fat, cholesterol, and processed meat were associated with higher rates of cardiovascular events in patients suffering from PAD. The current review found evidence of a beneficial impact of the Mediterranean diet including nuts in this target population. More RCTs and high-quality registries are needed that focus on nutritional habits among patients with PAD to design appropriate preventive programs.