Journal articles on the topic 'Fibre level simulation'
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Huang, Jin, Bo Xu, and Kun Qiu. "Modeling and Simulation of FC-AE-ASM Network." Advanced Materials Research 748 (August 2013): 941–45. http://dx.doi.org/10.4028/www.scientific.net/amr.748.941.
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Fibre Channel (FC) as a Universal Avionics Network (UAN) candidate solution for the advanced integrated avionics systems can enable high-bandwidth, low-latency, high-reliability and hard real-time communication on aircraft platforms spanning military and commercial applications. Fibre Channel Avionics Environment-Anonymous Subscriber Messaging protocol (FC-AE-ASM) is one of the five high level protocols in fiber channel avionic environment which is used to transport command, control, signal processing and sensor / video data of the aircraft[1,2].The objective of this paper is to conduct a modeling and simulation on the performance of the FC–AE-ASM network. Through modeling the message transmission of the FC-AE-ASM with accompanying Eclipse, some network performance parameters such as bandwidth, throughput and end-to-end message delay can be gained and analyzed.
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Monzón, Mario, Rubén Paz, Martí Verdaguer, Luis Suárez, Pere Badalló, Zaida Ortega, and Noelia Diaz. "Experimental Analysis and Simulation of Novel Technical Textile Reinforced Composite of Banana Fibre." Materials 12, no. 7 (April 7, 2019): 1134. http://dx.doi.org/10.3390/ma12071134.
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The use of natural fibres allows reducing environmental impact, due to their natural renewable origin and the lower energy needed for their production and processing. This work presents the mechanical characterization of a newly developed technical textile, with banana fibre treated by enzymes, comparing experimental results with numerical simulation based on the definition of the unit cell at micromechanical level. The experimental test shows that the composite with the fabric of banana fibre presents worse mechanical behaviour than the one with commercial flax fibre. The presence of wool, necessary for producing the yarn, reduces the mechanical properties of the banana textile. The numerical simulation had an acceptable error compared with the experimental results, with a global average error of 9%, showing that the predictive modelling based on the multiscale method is suitable for the design process of this kind of composite.
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Vigliotti, A., R. M. McMeeking, and V. S. Deshpande. "Simulation of the cytoskeletal response of cells on grooved or patterned substrates." Journal of The Royal Society Interface 12, no. 105 (April 2015): 20141320. http://dx.doi.org/10.1098/rsif.2014.1320.
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We analyse the response of osteoblasts on grooved substrates via a model that accounts for the cooperative feedback between intracellular signalling, focal adhesion development and stress fibre contractility. The grooved substrate is modelled as a pattern of alternating strips on which the cell can adhere and strips on which adhesion is inhibited. The coupled modelling scheme is shown to capture some key experimental observations including (i) the observation that osteoblasts orient themselves randomly on substrates with groove pitches less than about 150 nm but they align themselves with the direction of the grooves on substrates with larger pitches and (ii) actin fibres bridge over the grooves on substrates with groove pitches less than about 150 nm but form a network of fibres aligned with the ridges, with nearly no fibres across the grooves, for substrates with groove pitches greater than about 300 nm. Using the model, we demonstrate that the degree of bridging of the stress fibres across the grooves, and consequently the cell orientation, is governed by the diffusion of signalling proteins activated at the focal adhesion sites on the ridges. For large groove pitches, the signalling proteins are dephosphorylated before they can reach the regions of the cell above the grooves and hence stress fibres cannot form in those parts of the cell. On the other hand, the stress fibre activation signal diffuses to a reasonably spatially homogeneous level on substrates with small groove pitches and hence stable stress fibres develop across the grooves in these cases. The model thus rationalizes the responsiveness of osteoblasts to the topography of substrates based on the complex feedback involving focal adhesion formation on the ridges, the triggering of signalling pathways by these adhesions and the activation of stress fibre networks by these signals.
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Arnold, Edith M., and Scott L. Delp. "Fibre operating lengths of human lower limb muscles during walking." Philosophical Transactions of the Royal Society B: Biological Sciences 366, no. 1570 (May 27, 2011): 1530–39. http://dx.doi.org/10.1098/rstb.2010.0345.
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Muscles actuate movement by generating forces. The forces generated by muscles are highly dependent on their fibre lengths, yet it is difficult to measure the lengths over which muscle fibres operate during movement. We combined experimental measurements of joint angles and muscle activation patterns during walking with a musculoskeletal model that captures the relationships between muscle fibre lengths, joint angles and muscle activations for muscles of the lower limb. We used this musculoskeletal model to produce a simulation of muscle–tendon dynamics during walking and calculated fibre operating lengths (i.e. the length of muscle fibres relative to their optimal fibre length) for 17 lower limb muscles. Our results indicate that when musculotendon compliance is low, the muscle fibre operating length is determined predominantly by the joint angles and muscle moment arms. If musculotendon compliance is high, muscle fibre operating length is more dependent on activation level and force–length–velocity effects. We found that muscles operate on multiple limbs of the force–length curve (i.e. ascending, plateau and descending limbs) during the gait cycle, but are active within a smaller portion of their total operating range.
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Kondora, Grzegorz, and Dariusz Asendrych. "Modelling the Dynamics of Flexible and Rigid Fibres." Chemical and Process Engineering 34, no. 1 (March 1, 2013): 87–100. http://dx.doi.org/10.2478/cpe-2013-0008.
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Abstract A particle-level simulation technique has been developed for modelling fibre suspension flow in a converging channel of a papermachine headbox. The fibre model is represented by a chain of elements connected together. The model was verified by the simulation of rigid fibre dynamics in a simple shear flow. The period of rotation was found to be in a very good agreement with theory and reference data. The model was then employed to simulate fibre motion in a converging channel of a papermachine headbox. Fibre suspension motion was resolved using two-step procedure. Velocity field was calculated by means of a commercial CFD code ANSYS Fluent with RSM turbulence model applied and used as an input to the in-house code allowing to simulate fibre dynamics. Results of the calculations were used to construct the fibre orientation probability distribution (FOPD) which was found to be consistent with available experimental data.
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Sanusi, H., M. S. Hussin, A. R. Yuzairi, L. H. Peng, and M. F. A. Ahmad. "Finite element analysis of drilling unidirectional CFRP in different ply orientation." Journal of Mechanical Engineering and Sciences 14, no. 3 (September 30, 2020): 7258–68. http://dx.doi.org/10.15282/jmes.14.3.2020.25.0570.
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In the new era of Industrial Revolution 4.0 (IR 4.0), the manufacturing processes are facing a new level of flexible mass production technologies. Hence, the high demands for simulations data of manufacturing production and operation are required for developing a Cyber-Physical Systems of smart machines. Some composite machining processes could be very expansive. Simulation is needed to reduce the manufacturing time and cost. Without considering the suitable parameter of drilling, damage occurs at the region over the hole’s boundary after the drilling operation is done. Thus, the goal of this research is to investigate the effects of drilling cutting parameter such as thrust force, drilling-induced damage and stress distribution of reinforcing carbon composite polymer (CFRP) laminate by developing a user-defined material model (VUMAT) subroutine in ABAQUS/EXPLICIT (ABAQUS, Dassault Systèmes®) for different fibre ply orientations. The failure mode such as fibre tensile failure, fibre compressive failure, matrix cracking and matrix crushing was modelled and analysed based on Hashin and Puck’s criterion. The stages of drilling operation were observed and described in this paper with the drilling cutting parameter and the damage of composite was finely defined. The results proved that the relationship of thrust force is directly proportional to the feed rate with the difference of computational model are 8 % higher than the experiment. Among the ply orientation sequence applied in the simulation, the result shows that [ / / ] and [ / / ] ply having higher thrust force with 401.84 N.mm and 390.53 N.mm at 500 mm/min feed rate as delamination extent, as the frequency of fiber pulls out at the exit region of the drilled hole increases as compared to the restricted fiber ply orientation 0˚ and 90˚.
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Heimbs, Sebastian, Tim Wagner, Heinz Meister, Clemens Brand, and Mircea Calomfirescu. "Bird strike on aircraft radome: Dynamic characterisation of quartz fibre composite sandwich for accurate, predictive impact simulations." EPJ Web of Conferences 183 (2018): 01007. http://dx.doi.org/10.1051/epjconf/201818301007.
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This study assesses the bird strike resistance of the satellite communication (SatCom) radome of a medium altitude, long endurance (MALE) remotely piloted aircraft system (RPAS), which is designed as a lightweight sandwich structure with thin quartz fibre composite skins and a cellular honeycomb core. In order to perform accurate, predictive numerical bird strike simulations, the building block approach was applied, involving extensive experimental characterisation and model validation of the materials and structures from simple coupon level up to full-scale radome level. Coupon tests of the quartz fibre composite skin material under high-rate dynamic loading revealed significant strain rate effects, which needed to be taken into account in the simulation model in order to predict the structural response under high-velocity bird strike loading. In summary, this work presents a systematic and detailed approach for obtaining validated modelling methods for high-velocity impact analyses, which could be used efficiently for various design and parameter studies during the development of the SatCom radome.
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Muna, Isyna Izzal, and Magdalena Mieloszyk. "Temperature Influence on Additive Manufactured Carbon Fiber Reinforced Polymer Composites." Materials 14, no. 21 (October 26, 2021): 6413. http://dx.doi.org/10.3390/ma14216413.
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The popular applications of Additive Manufactured (AM) polymer materials in engineering, medical, and industrial fields have been widely recognized due to their high-speed production despite their complex design shapes. Fused Deposition Modeling (FDM) is the technique that has become the most renowned AM process due to its simplicity and because it is the cheapest method. The main objective of this research is to perform a numerical simulation of the thermo-mechanical behaviour of AM polymer with continuous carbon fibre reinforcement exposed to elevated temperatures. The influence of global thermal loads on AM material was focused on mechanical property changes at the microscale (level of fiber–matrix interaction). The mechanical response (strain/stress distribution) of the AM material on the temperature loading was modelled using the finite element method (FEM). The coupled thermal-displacement analysis was used during the numerical calculations. The strain in the sample due to its exposition on elevated temperature was measured using fibre Bragg grating (FBG) sensors. The numerical results were compared with the experimental results achieved for the sample exposure to the same thermal conditions showing good agreement. A strong influence of the temperature on the matrix structure and the condition of bondings between fibres and matrix was observed.
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Yi, T. "The Progressive Failure Analysis of Uni-Directional Fibre Reinforced Composite Laminates." Journal of Mechanics 36, no. 2 (February 24, 2020): 159–66. http://dx.doi.org/10.1017/jmech.2019.55.
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ABSTRACTThe three dimensional standard damage model developed by Lavedeze et.al [9, 13] for uni-directional fibre reinforced ply is implemented into the nonlinear solution of NX Nastran within composite solid element to analyze the progressive damage process and ultimate failure of fibre reinforced composite laminates. This ply level meso-damage-constitutive-model takes into account main damage mechanisms including fibre breaking, matrix transverse cracking, and fibre/matrix de-bonding; also considers contributions like plasticity coupling, damage delay effects, and elastic nonlinearity in fibre compression. Dissipated energy and damage status are also introduced to reflect the damage condition on the macrostructural-level. Using the implemented code, simulation is carried out on the uniaxial tension of a [±45]2s laminate with IM6/914 material, wherein the predicted ply shear rupture stress matches the experimental results very well and better than the theoretical predictions in literature. Moreover, a [-45/0/45/90] holed laminate loaded in tension is simulated to show the complex behavior of subcritical damage evolution and failure process in the composite structure. The composite solid element with damage model supported in NX Nastran is shown to be a reliable tool to analyze the progressive failure of uni-directional fibre reinforced composite laminates.
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Fat Cheung, Adrien M., and Klaudio Bari. "Novel Reactive Flex Configuration in Kiwi Wing Foil Surfboard." Journal of Composites Science 6, no. 1 (December 26, 2021): 6. http://dx.doi.org/10.3390/jcs6010006.
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The creation of an ideal surfboard is art. The design and construction depend on the individual surfer’s skill level and type of the required performance. In this research, four fuselage concepts were carefully explored to meet the following unique needs: lightweight, strong, and a fast-manufacturing process. The fuselages were manufactured by compression moulding using skin and core materials. The skin material was selected to be unidirectional (UD) carbon fibre, discontinuous carbon fibre (SMC) and Filava quadriaxial fibre impregnated with epoxy, while the core material was selected to be lightweight PVC foam. To assess the mechanical performance, three-point bending has been performed according to BS-ISO 14125 and validated using Finite Element Analysis (FEA) using Ansys software. As expected, the flexural test revealed that the UD carbon fibre fuselage was the strongest and SMC was the weakest, while large deflection was seen in Filava fibre fuselages before failure, showing great reactive flex that promotes projection during surfing. The experimental results show good agreement with FEA simulation, and the locations of the physical failure in the fuselage matches the location of maximum flexural stress obtained from FEA simulation. Although all fuselages were found to carry a surfer weight of 150 kg, including a factor of safety 3, except the SMC fuselage, due to shrinkage. The Filava fibre fuselages were seen to have a large deflection before failure, showing great flexibility to handle high ocean waves. This promotes the potential use of reactive flex in high performance sports equipment, such as surfing boards. A large shrinkage must be taken under consideration during compression moulding that depends on fibre orientation, resin nature, and part geometry.
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Pearce, Garth M., Shen Hin Lim, Jung Hoon Sul, B. Gangadhara Prusty, and Don W. Kelly. "Atoms to Assemblies: A Physics-Based Hierarchical Modelling Approach for Polymer Composite Components." Applied Mechanics and Materials 553 (May 2014): 41–47. http://dx.doi.org/10.4028/www.scientific.net/amm.553.41.
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The development of new composite materials requires analysis and experimentation spanning scales from nanometres to metres, from “atoms to assemblies”. In this paper, concerned primarily with fibre reinforced epoxy composites, a methodology is presented which allows continuum level structural simulation to account for nanoand micro-scale size effects in composites. The novelty of this approach is the modular hierarchical nature of the simulation which ensures computational tractability, regardless of the length scales considered. Linking the nanoscale to the macroscopic scale in a single simulation allows for holistic materials development, including the addition of nanoadditives to polymer resin systems.
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Dijkstra, Jan. "Simulation of the dynamics of protozoz in the rumen." British Journal of Nutrition 72, no. 5 (November 1994): 679–99. http://dx.doi.org/10.1079/bjn19940071.
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A modified mathematical model is described that simulates the dynamics of rumen micro-organisms, with specific emphasis on the rumen protozoa. The model is driven by continuous inputs of nutrients and consists of nineteen state variables, which represent the N, carbohydrate, fatty acid and microbial pools in the rumen. Several protozoal characteristics were represented in the model, including preference for utilization of starch and sugars compared with fibre, and of insoluble compared with soluble protein; engulfment and storage of starch; no utilization of NH3to synthesize amino acids; engulfment and digestion of bacteria and protozoa; selective retention within the rumen; death and lysis related to nutrient availability. Comparisons between model predictions and experimental observations showed reasonable agreement for protozoal biomass in the rumen, but protozoal turnover time was not predicted well. Sensitivity analyses highlighted the need for more reliable estimates of bacterial engulfment rate, protozoal maintenance requirement, and death rate. Simulated protozoal biomass was increased rapidly in response to increases in dietary starch content, but further increases in starch content of a high-concentrate diet caused protozoal mass to decline. Increasing the sugar content of a concentrate diet, decreased protozoa, while moderate elevations of the sugar content on a roughage diet increased protozoal biomass. Simulated protozoal biomass did not change in response to variations in dietary neutral-detergent fibre (NDF) content. Reductions in dietary N resulted in an increased protozoal biomass. Depending on the basal intake level and dietary composition, protozoal concentration in the rumen was either increased or decreased by changes in feed intake level. Such changes in relative amounts of protozoal and bacterial biomass markedly affected the supply of nutrients available for absorption. The integration of protozoal, bacterial and dietary characteristics through mathematical representation provided an improved understanding of mechanisms of protozoal responses to changes in dietary inputs.
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Zhou, Song, Yi Sun, Boyang Chen, and Tong-Earn Tay. "Progressive damage simulation of open-hole composite laminates under compression based on different failure criteria." Journal of Composite Materials 51, no. 9 (July 15, 2016): 1239–51. http://dx.doi.org/10.1177/0021998316659776.
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The strength prediction of open-hole fibre-reinforced composite laminate under compression is very important in the design of composite structures. The modelling of fibre, matrix damage and delamination plays an important role in the understanding of the damage mechanics of laminate under open-hole compression. In this article, a progressive damage model for open-hole compression that is based on continuum shell elements and cohesive elements is established to model in-plane damage and delamination, respectively. The damage mechanics of sublaminate-scaled laminates with ply sequence [45/0/−45/90]ms and ply-level-scaled laminates with ply sequence [45n/0n/−45n/90n]s are investigated by our proposed model. The Tsai-Wu and Hoffman failure criteria are employed for the determination of matrix damage initiation. Compared with the experiments, the numerical results using the Tsai-Wu criterion exhibit better accuracy regarding open-hole compression strength prediction and failure modes simulation.
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Bange, M. P., P. S. Carberry, J. Marshall, and S. P. Milroy. "Row configuration as a tool for managing rain-fed cotton systems: review and simulation analysis." Australian Journal of Experimental Agriculture 45, no. 1 (2005): 65. http://dx.doi.org/10.1071/ea03254.
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Rain-fed cotton production can be a significant proportion (average 17%) of the Australian Cotton Industry. One of the management techniques that rain-fed cotton growers have is to modify row configuration. Configurations that have entire rows missing from the sowing configuration are often referred to as ‘skip row’. Skip configurations are used to: increase the amount of soil water available for the crop, which can influence the potential lint yield; reduce the level of variability or risk associated with production; enhance fibre quality; and reduce input costs. Choosing the correct row configuration for a particular environment involves many, often complex, considerations. This paper presents an examination of how rain-fed cotton production in Australia is influenced by row configuration with different management and environmental factors. Data collated from field experiments and the cotton crop simulation model OZCOT, were used to explore the impact of agronomic decisions on potential lint yield and fibre quality and consequent economic benefit. Some key findings were: (i) soil water available at sowing did not increase the advantage of skip row relative to solid configurations; (ii) reduced row spacing (75 cm) did not alter lint yield significantly in skip row crops; (iii) skip row, rain-fed crops show reasonable plasticity in terms of optimum plant spacing within the row (simular to irrigated cotton); (iv) sowing time of rain-fed crops would appear to differ between solid and skip row arrangements; (v) skip row configurations markedly reduce the risk of price discounts due to short fibre or low micronaire and this should be carefully considered in the choice of row configuration; and (vi) skip configurations can also provide some savings in variable costs. In situations where rain-fed cotton sown in solid row configurations is subject to water stress that may affect lint yield or fibre quality, skip row configurations would be a preferential alternative to reduce risk of financial loss.
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Kelly, M. J., A. A. Swan, and K. D. Atkins. "Optimal use of on-farm fibre diameter measurement and its impact on reproduction in commercial Merino flocks." Australian Journal of Experimental Agriculture 47, no. 5 (2007): 525. http://dx.doi.org/10.1071/ea06222.
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The use of on-farm measurement of fibre diameter in clip preparation and selection was examined using a stochastic simulation. Commercial self-replacing Merino flocks were simulated, with each flock equivalent in stocking rate to a 2500-ewe flock with an average fibre diameter of 19 µm (with the same energy requirements as 4250 50-kg dry sheep). Returns from each selection and clip preparation strategy were based on a 5-year period from 1998 to 2003. The percentage of sales where it would have been profitable to utilise fibre diameter measurement in wool classing declined from 84% to less than 1% in 19- and 25-µm flocks, respectively. Clip preparation benefits reduced from AU$5.52 to $1.46 per dry sheep equivalent as the mean fibre diameter of the flock increased from 19 to 25 µm (under random selection). Selection on either fibre diameter or selection index (12% micron premium based on fibre diameter and fleece weight) was of benefit for 19- and 21-µm flocks, but not broader fibre diameter flocks. Flock reproductive performance was simulated at the individual animal level, based on the traits of fertility (ewes lambing per ewe joined), litter size (lambs born per ewe lambing) and lamb survival (lambs weaned per lamb born). These traits were simulated with genetic components, allowing the investigation of correlated responses in reproduction traits. Single-trait selection on fibre diameter did not significantly impact on reproduction traits but did reduce fibre diameter, fleece weight and bodyweight. There was a large variation in the returns from clip preparation, as the mean fibre diameter of the flock increased, and over selling periods, highlighting the importance of understanding the current market conditions and their relationship with the flock mean fibre diameter when considering the use of fibre diameter in clip preparation.
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Bilal, Mehak. "EDFA and Optical Fiber Repositioning in an Optical Fiber Communication Network." International Journal for Research in Applied Science and Engineering Technology 9, no. 11 (November 30, 2021): 1100–1105. http://dx.doi.org/10.22214/ijraset.2021.38874.
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Abstract: This study shows an easy and effective design of an optical fiber communication system, which demonstrates EDFA's ideal position in the whole system. In recent years, erbium-doped fiber amplifiers (EDFAs) have been more attentive with the development of high-speed and long-distance data transmission systems. In our research, EDFA's forward pump capacity is maintained at 100mW, and our three configurations modify and analyze the location of EDFA. First configuration is meant to place EDFA before optical fiber in the entire system. The second arrangement has been intended such that EDFA will precede optical fiber. EDFA is inserted in the third configuration between the optical fiber length. For the three setups, the BER, Q factor and output power level were observed, with the setup one having minimal BER, setup two with the greatest power, and setup three with the maximum Q factor. This paper discusses the causes behind these results and designers may construct an optical fiber communication system in the most efficient and reliable fashion by taking those results into consideration. The simulation was performed in Opti-System software. Keywords: EDFA, BER, Q factor, Analyzer, Optical fibre
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Haubi, C. U., F. L. Mould, C. K. Reynolds, and E. Owen. "Towards a continuous culture (Rusitec) model of rumen acidosis: effects of buffer concentration, non-protein nitrogen and concentrate level on pH and feed degradation." Proceedings of the British Society of Animal Science 2001 (2001): 130. http://dx.doi.org/10.1017/s1752756200005123.
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Rumen acidosis is a problem in many production systems where readily fermentable concentrates are fed. Although acidosis is more common as a subclinical condition that can impair fibre digestion, numerous factors can precipitate the clinical disorder. The objective of the present study was to begin development of a model of acidosis using a rumen simulation technique (Rusitec) and continuous pH monitoring for subsequent evaluation of contributing factors. In the present report the effect of reduced buffer concentration, non-protein nitrogen (NPN) addition and method of NPN provision on pH and feed dry matter disappearance were examined.
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Dijkstra, Jan, and Seerp Tamminga. "Simulation of the effects of diet on the contribution of rumen protozoa to degradation of fibre in the rumen." British Journal of Nutrition 74, no. 5 (November 1995): 617–34. http://dx.doi.org/10.1079/bjn19950166.
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A previously described mathematical model, that simulates the metabolic activities of rumen bacteria and protozoa, was used to examine the contribution of protozoa to neutral-detergent fibre (NDF) degradation in the rumen of cattle. Comparisons between predicted and experimentally observed NDF degradation showed general agreement. Further simulations were performed with diets containing variable proportions of concentrate (between 0 and 1 kg/kg diet DM) and at intake levels ranging between 5·3 and 21·0 kg DM/d. The simulated protozoal contribution to NDF degradation was 17–21% at the lowest intake level. Except for the all-concentrate diets, raising the feed intake level reduced this contribution to 5–3% at the highest intake level. The changes in contribution of protozoa to NDF degradation were related to variations in the fibrolytic bacteria: protozoa value and the NDF-degrading activities of protozoa predicted by the model. In simulations where dietary NDF levels were reduced and starch and sugar levels were increased independently, protozoal contribution to NDF degradation generally increased. These differences were reflected also in the generally increased protozoal contribution to NDF degradation predicted in response to a decreased roughage:concentrate value. The contribution of protozoa also generally declined in response to added N. These changes in predicted protozoal contribution to NDF degradation resulting from dietary variations provided possible explanations for the differences in rumen NDF degradation observed when animals are defaunated.
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Patel, Deepak K., and Anthony M. Waas. "Damage and failure modelling of hybrid three-dimensional textile composites: a mesh objective multi-scale approach." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 374, no. 2071 (July 13, 2016): 20160036. http://dx.doi.org/10.1098/rsta.2016.0036.
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This paper is concerned with predicting the progressive damage and failure of multi-layered hybrid textile composites subjected to uniaxial tensile loading, using a novel two-scale computational mechanics framework. These composites include three-dimensional woven textile composites (3DWTCs) with glass, carbon and Kevlar fibre tows. Progressive damage and failure of 3DWTCs at different length scales are captured in the present model by using a macroscale finite-element (FE) analysis at the representative unit cell (RUC) level, while a closed-form micromechanics analysis is implemented simultaneously at the subscale level using material properties of the constituents (fibre and matrix) as input. The N -layers concentric cylinder (NCYL) model (Zhang and Waas 2014 Acta Mech. 225 , 1391–1417; Patel et al. submitted Acta Mech. ) to compute local stress, srain and displacement fields in the fibre and matrix is used at the subscale. The 2-CYL fibre–matrix concentric cylinder model is extended to fibre and ( N −1) matrix layers, keeping the volume fraction constant, and hence is called the NCYL model where the matrix damage can be captured locally within each discrete layer of the matrix volume. The influence of matrix microdamage at the subscale causes progressive degradation of fibre tow stiffness and matrix stiffness at the macroscale. The global RUC stiffness matrix remains positive definite, until the strain softening response resulting from different failure modes (such as fibre tow breakage, tow splitting in the transverse direction due to matrix cracking inside tow and surrounding matrix tensile failure outside of fibre tows) are initiated. At this stage, the macroscopic post-peak softening response is modelled using the mesh objective smeared crack approach (Rots et al. 1985 HERON 30 , 1–48; Heinrich and Waas 2012 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference, Honolulu, HI, 23–26 April 2012 . AIAA 2012-1537). Manufacturing-induced geometric imperfections are included in the simulation, where the FE mesh of the unit cell is generated directly from micro-computed tomography (MCT) real data using a code S impleware . Results from multi-scale analysis for both an idealized perfect geometry and one that includes geometric imperfections are compared with experimental results (Pankow et al. 2012 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference, Honolulu, HI, 23–26 April 2012 . AIAA 2012-1572). This article is part of the themed issue ‘Multiscale modelling of the structural integrity of composite materials’.
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Chen, Ya, P. P. Maung, and G. V. Malysheva. "Investigating Curing Kinetics for a Thin-Walled Carbon Fibre Structure." Herald of the Bauman Moscow State Technical University. Series Mechanical Engineering, no. 5 (134) (October 2020): 58–70. http://dx.doi.org/10.18698/0236-3941-2020-5-58-70.
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The paper presents a computational method and an example of using it to derive parameters of a high-pressure filament-wound carbon fibre vessel designed for unmanned aerial vehicle applications. A feature of the vessel design is its variable thickness, which may result in temperature gradients, residual stresses, and diminished strength. We propose a method for assessing curing kinetics that takes into account the heat emitted during this process. We used the ESI PAM-RTM software package for simulation and determined that at the initial stage of the curing process the temperature and degree of curing in the thinner part of the product exceed those in its thicker part. As the degree of curing increases, the exothermic reaction taking place affects the temperature fields, which leads to an increase in temperatures and degree of curing in the thicker regions. In order to level the temperature gradients and degree of curing over the whole vessel, we propose to heat it at different rates. Our investigation results allowed us to establish the optimum manufacturing conditions ensuring the minimum temperature gradient values
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Margossian, Alexane, François Dumont, and Uwe Beier. "Validation of Macroscopic Forming Simulations of a Unidirectional Pre-Impregnated Material through Optical Measurements." Key Engineering Materials 554-557 (June 2013): 465–71. http://dx.doi.org/10.4028/www.scientific.net/kem.554-557.465.
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Presenting interesting aspects such as a high strength-to-weight ratio, Carbon Fibre Reinforced Plastic components are frequently used in the aerospace industry. The forming step, which conforms the reinforcement to a specific geometry, is a sensitive phase of the manufacturing process. In order to detect the occurrence of defects prior to any trial, forming methods are often simulated via finite element software. The presented work will detail the simulation validation of a double curved helicopter frame forming out of a unidirectional carbon fibre pre-impregnated material (M21E, Hexcel®). The finite element model was based on an explicit approach at a macroscopic level and developed via the commercially available software Visual-Crash PAM (ESI®) [1]. The validation was carried out on six different preforms. Measurements of the top layers were performed by an enhanced version of a 4D measuring system, originally developed for non-woven fabric [2], able to make reproducible photographic and height measurements (Fig. 1). Experimental results were then compared to simulated ones. Due to material specificities, the photo quality reached for non-crimp fabrics could not be achieved [2]. After hardware and software modifications, measurements and analyses were eventually successfully completed. The validation of the simulation reached an accuracy of 1° to 3° depending on the geometrical features of the preform (Fig. 2).
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Naresh, N., M. P. Jenarthanan, and R. Hari Prakash. "Multi-objective optimisation of CNC milling process using Grey-Taguchi method in machining of GFRP composites." Multidiscipline Modeling in Materials and Structures 10, no. 2 (August 5, 2014): 265–75. http://dx.doi.org/10.1108/mmms-06-2013-0042.
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Purpose – In milling process the surface roughness and delamination are the most important performance characteristics, which are influenced by many factors like fibre orientation angle, helix angle, feed rate and spindle speed. The selection of these parameters at optimum level plays a vital role in getting minimum surface roughness and delamination factor. The purpose of this paper is to present multi-objective optimisation of Computer Numerical Control milling parameters using Grey-Taguchi method to get minimum surface roughness and delamination factor in machining of glass fibre reinforced plastics (GFRP) composites used in automotive, aircraft and manufacture of space ships. Design/methodology/approach – The experiments are designed and conducted based on Taguchi's L27 orthogonal array by taking fibre orientation angle, helix angle, feed rate and spindle speed at three levels and responses are surface roughness and delamination factor. Taguchi's signal-to-noise (S/N) ratio are determined based on their performance characteristics. A Grey relation grade is obtained by using S/N ratio. Based on Grey relational grade value, optimum levels of parameters have been identified by using response table and response graph. Findings – Optimum levels of parameters for GFRP composites have been identified by using response table and response graph and the significant contributions of controlling parameters are estimated using analysis of variance. Originality/value – The combined effect of fibre orientation angle and helix angle during milling of GFRP composites using Grey relational analysis has not been previously attempted for analysis.
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Oromiehie, Ebrahim, Nilanjan Chakladar, Ginu Rajan, and B. Prusty. "Online Monitoring and Prediction of Thermo-Mechanics of AFP Based Thermoplastic Composites." Sensors 19, no. 6 (March 15, 2019): 1310. http://dx.doi.org/10.3390/s19061310.
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Precision sensing in the characterization of complex additive manufacturing processes such as the Automated Fibre Placement (AFP) technique is important since the process involves a significant level of uncertainty in terms of quality and integrity of the manufactured product. These uncertainties can be monitored by embedding optical fibre Bragg grating (FBGs) sensors which provide accurate and simultaneous measurement of strain and temperature during the AFP process. The embedded sensors have been shown to remain resilient in continuous health monitoring after manufacturing. The thermal history obtained from the FBG sensors demonstrates a reduction of temperature on the bottom ply by up to 25% when the plies are laid one above the other. A numerical tool is developed to identify the physical parameters which may be responsible for the rise/fall of the temperature during ply layup. The numerical findings agree well with the sensor data and is extended to capture a breadth of parametric studies through the layup simulation. The model provides a comprehensive insight to the characteristics of the laid and the laying ply from a thermo-mechanics perspective.
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Ghosh, Shyamal, Swarup Ghosh, and Subrata Chakraborty. "Seismic reliability analysis of reinforced concrete bridge pier using efficient response surface method–based simulation." Advances in Structural Engineering 21, no. 15 (May 9, 2018): 2326–39. http://dx.doi.org/10.1177/1369433218773422.
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Seismic reliability analysis of bridge structures during and succeeding an earthquake event is of significant importance. The more accurate and robust approach of seismic reliability analysis is based on direct Monte Carlo simulation technique. But it is computationally challenging due to the requirement of large number of nonlinear time history analyses. The response surface method–based metamodeling approach is a viable alternative in such situation. This study explores the advantage of moving least squares method–based adaptive response surface method compared to the usually applied least squares method–based response surface method for improved seismic reliability analysis of multi-span bridge pier. The nonlinear time history analyses of the bridge pier are performed in the OpenSees with fibre sections considering a ground motion bin corresponding to the specified hazard level of the bridge site. The seismic reliability analysis results obtained by the usual least squares method and the proposed moving least squares method–based response surface method are compared with that of obtained by more accurate direct Monte Carlo simulation technique to elucidate the effectiveness of the proposed approach.
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Saris, Nur Najahatul Huda, Osamu Mikami, Azura Hamzah, Sumiaty Ambran, and Chiemi Fujikawa. "A V-Shape Optical Pin Interface for Board Level Optical Interconnect." Photonics Letters of Poland 10, no. 1 (March 31, 2018): 20. http://dx.doi.org/10.4302/plp.v10i1.786.
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This paper introduces a new interface of an optical pin for Printed Circuit Boards (PCBs), the V-shape cut type which is an innovation from the 90-degree cut type optical pin. The effectiveness is determined by optical characteristics through OptiCAD and by experiment. The simulation used a model of ray tracing analysis which is a one to two (split) connection function model. For the experiment, a Polymer Optical Fibre (POF) V-shape optical pin has been fabricated. It was found that the V-shaped optical pin has a multi-branched function and is applicable to optical interconnection. Full Text: PDF ReferencesMikami, O., et al. Optical pin interface for 90-deg optical path conversion coupling to Printed Wiring Board. in Region 10 Conference (TENCON), 2016 IEEE. 2016. IEEE. CrossRef DeCusatis, C., Data center architectures, in Optical Interconnects for Data Centers. 2017, Elsevier. p. 3-41. CrossRef Duranton, M., D. Dutoit, and S. Menezo, Key requirements for optical interconnects within data centers, in Optical Interconnects for Data Centers. 2017, Elsevier. p. 75-94. CrossRef ITOH, Y., et al., Optical Coupling Characteristics of Optical Pin with 45° Micro Mirror for Optical Surface Mount Technology. Journal of The Japan Institute of Electronics Packaging, 2001. 4(6): p. 497-503. CrossRef Uchida, T. and O. Mikami, Optical surface mount technology. IEICE Transactions on Electronics, 1997. 80(1): p. 81-87. CrossRef Papakonstantinou, I., et al., Low-cost, precision, self-alignment technique for coupling laser and photodiode arrays to polymer waveguide arrays on multilayer PCBs. IEEE Transactions on Advanced Packaging, 2008. 31(3): p. 502-511. CrossRef Nakama, K., et al., Optical connection device. 2006, Google Patents. DirectLink Ramaswami, R., K. Sivarajan, and G. Sasaki, Optical networks: a practical perspective. 2009: Morgan Kaufmann. DirectLink Tong, X.C., Advanced materials for integrated optical waveguides. 2014: Springer. CrossRef
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Aldoumani, Nada, Cinzia Giannetti, Zakaria Abdallah, Fawzi Belblidia, Hamed Haddad Khodaparast, Michael I. Friswell, and Johann Sienz. "Optimisation of the Filament Winding Approach Using a Newly Developed In-House Uncertainty Model." Eng 1, no. 2 (October 13, 2020): 122–36. http://dx.doi.org/10.3390/eng1020008.
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The device under investigation in this paper consists of a float used to capture tidal energy, which is tethered by multiple flexible cables to a large barge-like reactor. The proposed float is made of a continuously wound glass-reinforced composite shell with stainless steel bolting plates integrated into the float walls to allow the connection of 5 stainless steel cables. Numerical computations are required to assess whether a delamination of the composite layers in the float is likely. The manufacturing of the device has various potential uncertainties that should be investigated, such as the number of the plies, the bond strength between the composite layers, and the fibre orientations of the composite material relative to the applied load. This paper provides a multi-level strategy to optimise the composite float system, which is manufactured from glass-reinforced plastic (GRP). In contrast to previous publications on the topic, the current work uses an efficient link between ANSYS Workbench and MATLAB through an in-house code that has been developed over 3 years. This allowed the whole process to be fully automated and to reduce the time and cost of the simulations. Previously, ANSYS APDL was linked to MATLAB, but limitations in terms of the geometry and boundary conditions made it impractical when compared to ANSYS Workbench for the simulation of complex features. This makes the current approach unique and rare when compared to the published work in the field. This approach allows the use of a huge number of trials and is able to reduce the number of parameters to be studied by selecting the most sensitive ones. Additionally, the developed tools may be used for the efficient, robust optimisation of the proposed structure. The current study has focused on exploring the effects of the fibre orientations and the optimum number of plies on the overall performance of the structure.
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Salahuddin, Asif, Jingshu Wu, and C. K. Aidun. "Numerical study of rotational diffusion in sheared semidilute fibre suspension." Journal of Fluid Mechanics 692 (December 21, 2011): 153–82. http://dx.doi.org/10.1017/jfm.2011.501.
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AbstractFibre-level computer simulation is carried out to study the rotational diffusion and structural evolution of semidilute suspensions of non-Brownian, rigid-rod-like fibres under shear flow in a Newtonian fluid. The analyses use a hybrid approach where the lattice-Boltzmann method is coupled with the external boundary force method. The probability distribution of the orbit constant, $p({C}_{b} )$, in the semidilute regime is predicted with this method. The paper emphasizes assessment of the characteristics of a rotary diffusion model – anisotropic in nature (Koch, Phys. Fluids, vol. 7, 1995, pp. 2086–2088) – when used in suspensions with fibres of different aspect ratios (ranging from ${r}_{p} = 16$ to $72$) and with different volume concentrations (ranging from ${c}_{v} = 7. 58\ensuremath{\times} 1{0}^{\ensuremath{-} 3} $ to $6. 14\ensuremath{\times} 1{0}^{\ensuremath{-} 2} $). A measure of the scalar Folgar–Tucker constant, ${C}_{I} $, is extracted from the anisotropic diffusivity tensor, $ \mathbisf{C} $. The scalar ${C}_{I} $ is mostly $O(1{0}^{\ensuremath{-} 4} )$ in the semidilute regime and compares very well with the experimental observations of Stover (PhD thesis, School of Chemical Engineering, Cornell University, 1991) and Stover, Koch & Cohen (J. Fluid Mech., vol. 238, 1992, pp. 277–296). The ${C}_{I} $ values provide substantial numerical evidence that the range of ${C}_{I} $ (0.0038–0.0165) obtained by Folgar & Tucker (J. Rein. Plast. Compos., vol. 3, 1984, pp. 98–119) in the semidilute regime is actually overly diffusive. The paper also branches out to incorporate anisotropic diffusion (through the use of the Koch model) in the second-order evolution equation for $ \mathbisf{A} $ (a second-order orientation tensor). The solution of the evolution equation with the Koch model demonstrates unphysical behaviour at low concentrations. The most plausible explanation for this behaviour is error in the closure approximation; and the use of the Koch model in a spherical harmonics-based method (Montgomery-Smith, Jack & Smith, Compos. A: Appl. Sci. Manuf., vol. 41, 2010, pp. 827–835) to solve for the orientation moments corroborates this claim.
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Hong, Jung-Pyo, Jun-Jae Lee, Hwanmyeong Yeo, Chul-Ki Kim, Sung-Jun Pang, and Jung-Kwon Oh. "Parametric study on the capability of three-dimensional finite element analysis (3D-FEA) of compressive behaviour of Douglas fir." Holzforschung 70, no. 6 (June 1, 2016): 539–46. http://dx.doi.org/10.1515/hf-2015-0151.
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Abstract This study is aiming at the simulation of wood compression (C) at a macroscopic level by means of a three-dimensional finite element analysis (3D-FEA) of solid wood and evaluation of the capability and limitations of this approach. C-Tests were carried out on Douglas fir according to ASTM D 143. The specimens included the 25×25×100 mm3 cuboid bars for longitudinal (L), radial (R) and tangential (T) directions and the conventional 50×50×150 mm3 blocks for the perpendicular to grain (⊥) direction. Two sets of wood parameters were developed and the 3D-FEA was implemented for the two types of specimens. The 3D-FEA worked successfully provided that the stress state coming from the total wood C was uniform. However, in case of the dominance of local compressive behaviour such as bearing, crushing and fibre shear, a microscopic-level modelling technique is needed for correction of the material parameters. More details on the limitations and difficulties of 3D-FE implementation for wood were discussed.
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Gil Sevillano, J., D. González, and J. M. Martínez-Esnaola. "Heterogeneous Deformation and Internal Stresses Developed in BCC Wires by Axisymmetric Elongation." Materials Science Forum 550 (July 2007): 75–84. http://dx.doi.org/10.4028/www.scientific.net/msf.550.75.
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BCC wires macroscopically deformed by axisymmetric elongation (wire drawing) develop an intense <011> fibre texture and exhibit a characteristic non-uniform deformation of the grains evident in transverse sections (grain curling or “Van Gogh sky structure”). The extraordinary grain morphology induced by the <011> fibre texture is also accompanied by a peculiar constant strain hardening rate in single-phase BCC wires (exponentially increasing in case of BCC containing composite wires) that allows to reach very high strengths. Here we present a calculation of the elastoplastic axial elongation of such an aggregate of BCC grains with the ideal <011> fibre texture, using a slip-gradient dependent large-strain crystal plasticity constitutive equation incorporated into a finite element method (FEM) code, i.e., with proper account of the influence of the evolving shape and size of individual grains and of the local grain interactions. The results reproduce well the observed macroscopic behaviour (linear flow stress-strain curve at large strains) and the peculiar mesoscopic structural changes (grain curling in transverse sections). The simulation is focused on the analysis of strain and dislocation density heterogeneities and on the building up of mesoscopic (inter- and intra-granular) internal stresses during deformation. The computed average transverse tensile stresses acting normal to the axially oriented {100} planes approximately parallel to the boundaries of the flattened grains is close to 0.3 times the tensile flow stress of the aggregate, in good agreement with previous calculations based on the Taylor-Bishop-Hill model or on elasticplastic self-consistent calculations and with available neutron diffraction measurements. Such a high level of internal tensile stresses explains the well-known tendency of high strength BCC wires to fail by longitudinal splitting.
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Pukl, Radomír, Tereza Sajdlová, Drahomír Novák, and David Lehký. "Fracture-Mechanical Parameters for Modeling of Quasi-Brittle Materials and Structures." Advanced Materials Research 1106 (June 2015): 106–9. http://dx.doi.org/10.4028/www.scientific.net/amr.1106.106.
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The scatter of experimental results using specimens made of quasi-brittle materials, such as concrete, fibre-reinforced concrete, ultra high performance concrete etc., can be due to their heterogeneity rather high. An assessment of fracture-mechanical parameters is then difficult and problematic. To remain at deterministic level is therefore unrealistic and without virtual statistical approach, simulation and probabilistic result assessment the consequent practical design of quasi-brittle material-based structures can be risky. A key parameter of nonlinear fracture mechanics modeling is fracture energy of concrete. Numerical simulation of concrete failure and fracture phenomena in concrete as well as other cementitious materials became a field of an intensive research in the recent years. With respect to accuracy and efficiency of corresponding numerical models some few still open questions have to be focused. How the heterogeneity of cementitious materials can be taken into consideration in the most realistic way using commercially available finite element programs? A sophisticated option to get the parameters of the computational model indirectly is based on combination of fracture test with inverse analysis. This paper describes a methodology to get such parameters using experimental data from three-point bending tests used in inverse analysis based on combination of artificial neural networks and stochastic analysis.
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Whiteley, Jonathan P. "An evaluation of some assumptions underpinning the bidomain equations of electrophysiology." Mathematical Medicine and Biology: A Journal of the IMA 37, no. 2 (November 1, 2019): 262–302. http://dx.doi.org/10.1093/imammb/dqz014.
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Abstract Tissue level cardiac electrophysiology is usually modelled by the bidomain equations, or the monodomain simplification of the bidomain equations. One assumption made when deriving the bidomain equations is that both the intracellular and extracellular spaces are in electrical equilibrium. This assumption neglects the disturbance of this equilibrium in thin regions close to the cell membrane known as Debye layers. We first demonstrate that the governing equations at the cell, or microscale, level may be adapted to take account of these Debye layers with little additional complexity, provided the permittivity within the Debye layers satisfies certain conditions that are believed to be satisfied for biological cells. We then homogenize the microscale equations using a technique developed for an almost periodic microstructure. Cardiac tissue is usually modelled as sheets of cardiac fibres stacked on top of one another. A common assumption is that an orthogonal coordinate system can be defined at each point of cardiac tissue, where the first axis is in the fibre direction, the second axis is orthogonal to the first axis but lies in the sheet of cardiac fibres and the third axis is orthogonal to the cardiac sheet. It is assumed further that both the intracellular and extracellular conductivity tensors are diagonal with respect to these axes and that the diagonal entries of these tensors are constant across the whole tissue. Using the homogenization technique we find that this assumption is usually valid for cardiac tissue, but highlight situations where the assumption may not be valid.
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Erdemir, Ahmet, Craig Bennetts, Sean Davis, Akhil Reddy, and Scott Sibole. "Multiscale cartilage biomechanics: technical challenges in realizing a high-throughput modelling and simulation workflow." Interface Focus 5, no. 2 (April 6, 2015): 20140081. http://dx.doi.org/10.1098/rsfs.2014.0081.
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Understanding the mechanical environment of articular cartilage and chondrocytes is of the utmost importance in evaluating tissue damage which is often related to failure of the fibre architecture and mechanical injury to the cells. This knowledge also has significant implications for understanding the mechanobiological response in healthy and diseased cartilage and can drive the development of intervention strategies, ranging from the design of tissue-engineered constructs to the establishment of rehabilitation protocols. Spanning multiple spatial scales, a wide range of biomechanical factors dictate this mechanical environment. Computational modelling and simulation provide descriptive and predictive tools to identify multiscale interactions, and can lead towards a greater comprehension of healthy and diseased cartilage function, possibly in an individualized manner. Cartilage and chondrocyte mechanics can be examined in silico , through post-processing or feed-forward approaches. First, joint–tissue level simulations, typically using the finite-element method, solve boundary value problems representing the joint articulation and underlying tissue, which can differentiate the role of compartmental joint loading in cartilage contact mechanics and macroscale cartilage field mechanics. Subsequently, tissue–cell scale simulations, driven by the macroscale cartilage mechanical field information, can predict chondrocyte deformation metrics along with the mechanics of the surrounding pericellular and extracellular matrices. A high-throughput modelling and simulation framework is necessary to develop models representative of regional and population-wide variations in cartilage and chondrocyte anatomy and mechanical properties, and to conduct large-scale analysis accommodating a multitude of loading scenarios. However, realization of such a framework is a daunting task, with technical difficulties hindering the processes of model development, scale coupling, simulation and interpretation of the results. This study aims to summarize various strategies to address the technical challenges of post-processing-based simulations of cartilage and chondrocyte mechanics with the ultimate goal of establishing the foundations of a high-throughput multiscale analysis framework. At the joint–tissue scale, rapid development of regional models of articular contact is possible by automating the process of generating parametric representations of cartilage boundaries and depth-dependent zonal delineation with associated constitutive relationships. At the tissue–cell scale, models descriptive of multicellular and fibrillar architecture of cartilage zones can also be generated in an automated fashion. Through post-processing, scripts can extract biphasic mechanical metrics at a desired point in the cartilage to assign loading and boundary conditions to models at the lower spatial scale of cells. Cell deformation metrics can be extracted from simulation results to provide a simplified description of individual chondrocyte responses. Simulations at the tissue–cell scale can be parallelized owing to the loosely coupled nature of the feed-forward approach. Verification studies illustrated the necessity of a second-order data passing scheme between scales and evaluated the role that the microscale representative volume size plays in appropriately predicting the mechanical response of the chondrocytes. The tools summarized in this study collectively provide a framework for high-throughput exploration of cartilage biomechanics, which includes minimally supervised model generation, and prediction of multiscale biomechanical metrics across a range of spatial scales, from joint regions and cartilage zones, down to that of the chondrocytes.
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Soliva, Carla R., Leo Meile, Adam Cieślak, Michael Kreuzer, and Andrea Machmüller. "Rumen simulation technique study on the interactions of dietary lauric and myristic acid supplementation in suppressing ruminal methanogenesis." British Journal of Nutrition 92, no. 4 (October 2004): 689–700. http://dx.doi.org/10.1079/bjn20041250.
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The interactions of lauric (C12) and myristic acid (C14) in suppressing ruminal methanogenesis and methanogens were investigated with the rumen simulation technique (Rusitec) using bovine ruminal fluid. The fatty acids were added to basal substrates (grass hay:concentrate, 1:1.5) at a level of 48 g/kg DM, provided in C12:C14ratios of 5:0, 4:1, 3:2, 2·5:2.5, 2:3, 1:4 and 0:5. Additionally, an unsupplemented control consisting of the basal substrates only was employed. Incubation periods lasted for 15 (n4) and 25 (n2) d. CH4formation was depressed by any fatty acid mixture containing at least 40 % C12, and effects persisted over the complete incubation periods. The greatest depression (70 % relative to control) occurred with a C12:C14ratio of 4:1, whereas the second most effective treatment in suppressing CH4production (60 % relative to control) was found with a ratio of 3:2. Total methanogenic counts were decreased by those mixtures of C12and C14also successful in suppressing methanogenesis, the 4:1 treatment being most efficient (60 % decline). With this treatment in particular, the composition of the methanogenic population was altered in such a way that the proportion ofMethanococcalesincreased andMethanobacterialesdecreased. Initially, CH4suppression was associated with a decreased fibre degradation, which, however, was reversed after 10 d of incubation. The present study demonstrated a clear synergistic effect of mixtures of C12and C14in suppressing methanogenesis, mediated probably by direct inhibitory effects of the fatty acids on the methanogens.
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K M, Alagappan, Vijayaraghavan S, Jenarthanan M P, and Giridharan R. "Optimization of process parameters on drilling of natural fibres reinforced in epoxy resin matrices using Taguchi–Grey relational analysis." Multidiscipline Modeling in Materials and Structures 16, no. 5 (April 17, 2020): 937–49. http://dx.doi.org/10.1108/mmms-06-2019-0108.
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PurposeThe purpose of this paper is to identify the ideal process parameters to be set for the drilling of hybrid fibre-reinforced polymer (FRP) (kenaf and banana) composite using High-Speed Steel drill bits (5, 10, 15 mm) coated with tungsten carbide by means of statistical reproduction of the delamination factor and machining force using Taguchi–Grey Relational Analysis.Design/methodology/approachThe contemplated process parameters are Feed, Speed and Drill Diameter. The trials were carried out by taking advantage of the L-27 factorial design by Taguchi. Three factors, the three level Taguchi Orthogonal Array design in Grey Relational Analysis was used to carry out the trial study. Video Measuring System was used to identify the damage around the drill region. “Minitab 18” was used to examine the data collected by taking advantage of the various statistical and graphical tools available. Examination of variance is used to legitimize the model in identifying the most notable parameter.FindingsThe optimised set of input parameters were found out successfully which are as follows: Feed Rate: 450 mm/min, Cutting Speed: 3,000 rpm and Drill Diameter of 5 mm. When these values are fed in as input the optimised output is being obtained. From ANOVA analysis, it is apparent that the Speed (contribution of 92.6%) is the most influencing parameter on the delamination factor and machining force of the FRP material.Originality/valueOptimization of process parameters on drilling of natural fibres reinforced in epoxy resin matrices using Taguchi–Grey Relational Analysis has not been previously explored.
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Tao Mengmeng, 陶蒙蒙, 叶锡生 Ye Xisheng, 叶景峰 Ye Jingfeng, 余婷 Yu Ting, 全昭 Quan Zhao, 漆云凤 Qi Yunfeng, 冯国斌 Feng Guobin, and 陈卫标 Chen Weibiao. "同带泵浦千瓦级掺铥光纤激光器输出特性理论模拟." Chinese Journal of Lasers 49, no. 1 (2022): 0101019. http://dx.doi.org/10.3788/cjl202249.0101019.
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Alotaibi, Hatim, Chamil Abeykoon, Constantinos Soutis, and Masoud Jabbari. "Numerical Simulation of Two-Phase Flow in Liquid Composite Moulding Using VOF-Based Implicit Time-Stepping Scheme." Journal of Composites Science 6, no. 11 (November 3, 2022): 330. http://dx.doi.org/10.3390/jcs6110330.
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The filling stage in injection/infusion moulding processes plays a key role in composite manufacturing that can be influenced by the inlet and vent ports. This will affect the production of void-free parts and the desirable process time. Flow control is usually required in experiments to optimise such a stage; however, numerical simulations can be alternatively used to predict manufacturing-induced deficiencies and potentially remove them in the actual experiments. This study uses ANSYS Fluent software to model flow-front advancement during the impregnation of woven fabrics. A developed technique is applied by creating tracking points (e.g., on-line monitor) in the direction of the flow to report/collect data for flow-front positions as a function of time. The study adopts the FVM-VOF-based two-phase flow model together with an implicit time-stepping scheme, i.e., a dual-time formulation solution method with a preconditioned pseudo-time derivative. Initially, three time-step sizes, 5 s (small), 25 s, and 50 s (large), are evaluated to examine their impact on numerical saturation lines at various fabric porosities, 40%, 50%, and 60%, for a two-dimensional (2D) rectangular mould, and predictions are then compared with the well-known analytical Darcy. This is followed by a three-dimensional (3D) curved mould for a fillet L-shaped structure, wherein the degree-of-curvature of fibre preforms is incorporated using a User-Defined Function (UDF) to tailor the impregnation process. The developed approach shows its validation (1–5.7%) with theoretical calculations and experimental data for 2D and 3D cases, respectively. The results also stress that a shorter computational time can be achieved with a large time-step size while maintaining the same level of accuracy.
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Aychilie, Desalegn Beshaw, Yordan Kyosev, and Mulat Alubel Abtew. "Automatic Modeller of Textile Yarns at Fibre Level." Materials 15, no. 24 (December 13, 2022): 8887. http://dx.doi.org/10.3390/ma15248887.
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This paper presents a geometrical modelling principle for the modelling of yarns at the fibre level. The woven and the knitted textile structures are built of yarns, which on the other side, are fibrous assemblies. In many yarn and fabric modelling works, yarns are considered as a single line element; however, most yarns are composed of a number of staple or filament fibres. It is then very important to understand the yarn at the micro level for a better understanding, production and application of the above structures. The current paper aims to present the modelling and implementation of yarn structures at the fibre level using the algorithmic geometrical modelling principle. The research work uses basic assumptions for the building of the models and various implementation issues, connected with the proper representation of the single multi-filament yarns, plied yarns and finally the staple fibre yarns. Except for visualization, the generated yarn models are prepared as a basis for mechanical, thermal, fluid flow and other simulations of textile structures using FEM, CFD and other numerical tools.
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OLALEKAN, APENA WALIU, OLASUNKANMI OMOWUMI GRACE, and SALAKO ANUOLUWAPO. "PERFORMANCE EVALUATION OF ETHERNET TRANSMISSION USING M-ARY PULSE AMPLITUDE MODULATION TECHNIQUES." Journal of Engineering Studies and Research 26, no. 4 (January 8, 2021): 74–85. http://dx.doi.org/10.29081/jesr.v26i4.239.
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Low installation costs and high data rates reaching up to 10 Gbps, characterized Ethernet as the local area network (LAN) technology of choice to satisfy the increasing need for high-speed data transmission in packet-based networks. As demand for high speeds in data has increased, copper Ethernet has been integrated to handle these higher speeds. The IEEE 802.3ae* 2002 (10 Gigabit Ethernet) standard is based on data transmission over optical fibre only and in full-duplex mode. This study considered performance evaluation of Pulse Amplitude Modulation (PAM) and multilevel (PAM-16) technology in comparison with other PAM versions was carried out to investigate copper Ethernet with respect to higher speed characteristic and error performance. The evaluation was carried out in MATLAB R2017b simulation environment; this provides calculated bit error rates (BER) of the considered modulation schemes under different channel conditions. The results show that PAM-16 has a BER of .which is significantly lower than that of PAM-2 and PAM-4. Additionally, Hamming code were used to detect and correct errors that are inherent in the design and the efficiency of each level of PAM used was analyzed.
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Green, D. M., and C. T. Whittemore. "Architecture of a harmonized model of the growing pig for the determination of dietary net energy and protein requirements and of excretions into the environment (IMS Pig)." Animal Science 77, no. 1 (April 2003): 113–26. http://dx.doi.org/10.1017/s1357729800053716.
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AbstractThe model incorporates, amongst its novel components, variable efficiency coefficients in the simulation of the responses of growing pigs to nutrient inputs, and thereby increases the accuracy and efficacy of control of feeding and nitrate excretion. The model determines (rather than is presented with) net energy and required amino acid level and balance. The estimation of protein turn-over as a function of rate of protein retention, protein mass and the maturity of the pig was found to be central to both the energy (ATP) and protein economy. Protein turn-over varied from around 0·14 to 0·08 of the protein mass depending upon the size of the pig. Efficiencies of energy yield from lipid, starch (and sugar), protein and (fibre-derived) volatile fatty acids were calculated to be 0·98, 0·86, 0·56 and 0·58 for ATP production and 0·90, 0·70, 0·50, and 0·44 for lipid retention, respectively. The maximum efficiency of use of ileal digestible amino acids was determined as around 0·85. The energy cost of protein synthesis was equivalent to 4·2 MJ metabolizable energy (ME) per kg, and the efficiency of use of ME for protein retention varied from 0·55 to 0·40 depending on the protein mass of the pig. The components of the model and the biochemical drivers are described in detail, and proof of principle of the main elements is presented. The model is different in its architecture to other published simulation models, and is considered to add to the present knowledge base in this discipline.
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Fitzgerald, Sarah, Aileen Murphy, Ann Kirby, Fiona Geaney, and Ivan J. Perry. "Cost-effectiveness of a complex workplace dietary intervention: an economic evaluation of the Food Choice at Work study." BMJ Open 8, no. 3 (March 2018): e019182. http://dx.doi.org/10.1136/bmjopen-2017-019182.
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ObjectiveTo evaluate the costs, benefits and cost-effectiveness of complex workplace dietary interventions, involving nutrition education and system-level dietary modification, from the perspective of healthcare providers and employers.DesignSingle-study economic evaluation of a cluster-controlled trial (Food Choice at Work (FCW) study) with 1-year follow-up.SettingFour multinational manufacturing workplaces in Cork, Ireland.Participants517 randomly selected employees (18–65 years) from four workplaces.InterventionsCost data were obtained from the FCW study. Nutrition education included individual nutrition consultations, nutrition information (traffic light menu labelling, posters, leaflets and emails) and presentations. System-level dietary modification included menu modification (restriction of fat, sugar and salt), increase in fibre, fruit discounts, strategic positioning of healthier alternatives and portion size control. The combined intervention included nutrition education and system-level dietary modification. No intervention was implemented in the control.OutcomesThe primary outcome was an improvement in health-related quality of life, measured using the EuroQoL 5 Dimensions 5 Levels questionnaire. The secondary outcome measure was reduction in absenteeism, which is measured in monetary amounts. Probabilistic sensitivity analysis (Monte Carlo simulation) assessed parameter uncertainty.ResultsThe system-level intervention dominated the education and combined interventions. When compared with the control, the incremental cost-effectiveness ratio (€101.37/quality-adjusted life-year) is less than the nationally accepted ceiling ratio, so the system-level intervention can be considered cost-effective. The cost-effectiveness acceptability curve indicates there is some decision uncertainty surrounding this, arising from uncertainty surrounding the differences in effectiveness. These results are reiterated when the secondary outcome measure is considered in a cost–benefit analysis, whereby the system-level intervention yields the highest net benefit (€56.56 per employee).ConclusionsSystem-level dietary modification alone offers the most value per improving employee health-related quality of life and generating net benefit for employers by reducing absenteeism. While system-level dietary modification strategies are potentially sustainable obesity prevention interventions, future research should include long-term outcomes to determine if improvements in outcomes persist.Trial registration numberISRCTN35108237; Post-results.
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Mohd Ramli, Nurul Amira, Mohd Hafiz Fazalul Rahiman, Latifah Munirah Kamarudin, Latifah Mohamed, Ammar Zakaria, Anita Ahmad, and Ruzairi Abdul Rahim. "A New Method of Rice Moisture Content Determination Using Voxel Weighting-Based from Radio Tomography Images." Sensors 21, no. 11 (May 26, 2021): 3686. http://dx.doi.org/10.3390/s21113686.
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This manuscript presents a new method to monitor and localize the moisture distribution in a rice silo based on tomography images. Because the rice grain is naturally hygroscopic, the stored grains’ quality depends on their level of moisture content. Higher moisture content leads to fibre degradation, making the grains too frail and possibly milled. If the moisture is too low, the grains become brittle and are susceptible to higher breakage. At present, the single-point measurement method is unreliable because the moisture build-up inside the silo might be distributed unevenly. In addition, this method mostly applies gravimetric analysis, which is destructive. Thus, we proposed a radio tomographic imaging (RTI) system to address these problems. Four simulated phantom profiles at different percentages of moisture content were reconstructed using Newton’s One-Step Error Reconstruction and Tikhonov Regularization algorithms. This simulation study utilized the relationship between the maximum voxel weighting of the reconstructed RTI image and the percentage of moisture content. The outcomes demonstrated promising results, in which the weighting voxel linearly increased with the percentage of moisture content, with a correlation coefficient higher than 0.95 was obtained. Therefore, the results support the possibility of using the RTI approach for monitoring and localizing the moisture distribution inside the rice silo.
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Bova, Anthony S., William E. Mell, and Chad M. Hoffman. "A comparison of level set and marker methods for the simulation of wildland fire front propagation." International Journal of Wildland Fire 25, no. 2 (2016): 229. http://dx.doi.org/10.1071/wf13178.
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Simulating an advancing fire front may be achieved within a Lagrangian or Eulerian framework. In the former, independently moving markers are connected to form a fire front, whereas in the latter, values representing the moving front are calculated at points within a fixed grid. Despite a mathematical equivalence between the two methods, it is not clear that both will produce the same results when implemented numerically. Here, we describe simulations of fire spread created using a level set Eulerian approach (as implemented in the wildland–urban interface fire dynamics simulator, WFDS) and a marker method (as implemented in FARSITE). Simulations of surface fire spread, in two different fuels and over domains of increasing topographical complexity, are compared to evaluate the difference in outcomes between the two models. The differences between the results of the two models are minor, especially compared with the uncertainties inherent in the modelling of fire spread.
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Bassa, C. G., O. R. Hainaut, and D. Galadí-Enríquez. "Analytical simulations of the effect of satellite constellations on optical and near-infrared observations." Astronomy & Astrophysics 657 (January 2022): A75. http://dx.doi.org/10.1051/0004-6361/202142101.
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Context. The number of satellites in low-Earth orbit is increasing rapidly and many tens of thousands of satellites are expected to be launched in the coming years. There is a strong concern among the astronomical community about the contamination of optical and near-infrared observations by satellite trails, what has led to several initial investigations of the impact of large satellite constellations. Aims. We expand the impact analysis of such constellations on ground-based optical and near-infrared astronomical observations in a more rigorous and quantitative way, using updated constellation information and considering imagers and spectrographs and their very different characteristics. Methods. We introduce an analytical method that allows us to rapidly and accurately evaluate the effect of a very large number of satellites, accounting for their magnitudes and the effect of trailing of the satellite image during the exposure. We use this to evaluate the impact on a series of representative instruments, including imagers (traditional narrow field instruments, wide-field survey cameras, and astro-photographic cameras) and spectrographs (long-slit and fibre-fed), taking their limiting magnitude into account. Results. Confirming earlier findings, the effect of satellite trails is more damaging for high-altitude satellites, on wide-field instruments, or essentially during the first and last hours of the night. Thanks to their brighter limiting magnitudes, low- and mid-resolution spectrographs will be less affected, but the contamination will be at about the same level as that of the science signal, introducing additional challenges. High-resolution spectrographs will essentially be immune. We propose a series of mitigating measures, including one that uses the described simulation method to optimise the scheduling of the observations. We conclude that no single mitigation measure will solve the problem of satellite trails for all instruments and all science cases.
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Vamanu, Emanuel, Florentina Gatea, Ionela Sârbu, and Diana Pelinescu. "An In Vitro Study of the Influence of Curcuma longa Extracts on the Microbiota Modulation Process, In Patients with Hypertension." Pharmaceutics 11, no. 4 (April 18, 2019): 191. http://dx.doi.org/10.3390/pharmaceutics11040191.
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The multiple causes of cardiovascular diseases signify a major incidence and developmental risk of this pathology. One of the processes accountable for this pathologic development is the instauration of dysbiosis and its connection with an inflammatory process. Low antioxidant colonic protection encourages the progression of inflammation, with cardiovascular dysfunctions being a secondary consequence of the dysbiosis. Curcumin is one of the bioactive compounds displaying promising results for the reduction of an inflammatory process. The present study aims at demonstrating the capacity of three extracts drawn from Curcuma (C.) longa through an in vitro simulation process, for microbiota modulation in patients with hypertension. The acidic pH in the extraction process determined a high curcumin content in the extracts. The major phenolic compound identified was curcumin III, 622 ± 6.88 µg/mL for the ethanol/water/acetic acid extract. Low EC50 values were associated (0.2 µg/mL for DPPH scavenging activity) with the presence of curcumin isomers. A metabolic pattern became evident because the relationship between the short-chain fatty acids acted as a clinical biomarker. The curcumin present stimulated the formation of butyric and propionic acids. Microbiota activity control included a high degree of curcumin degradation and biotransformation in the other phenolic compounds. This developmental process was supported by the progression in the enterobacteria with a corresponding escalation in the pH level. The metabolomic pattern demonstrated a performance similar to the administration of dietary fibre, with the positive effects being dose-dependent.
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Kriwet, Alexander, and Markus Stommel. "The Impact of Fiber Orientation on Structural Dynamics of Short-Fiber Reinforced, Thermoplastic Components—A Comparison of Simulative and Experimental Investigations." Journal of Composites Science 6, no. 4 (April 1, 2022): 106. http://dx.doi.org/10.3390/jcs6040106.
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The quality of the fiber orientation of injection molding simulations and the transferred fiber orientation content, due to the process–structure coupling, influence the material modeling and thus the prediction of subsequently performed structural dynamics simulations of short-fiber reinforced, thermoplastic components. Existing investigations assume a reliable prediction of the fiber orientation in the injection molding simulation. The influence of the fiber orientation models and used boundary conditions of the process–structure coupling is mainly not investigated. In this research, the influence of the fiber orientation from injection molding simulations on the resulting structural dynamics simulation of short-fiber reinforced thermoplastic components is investigated. The Advani–Tucker Equation with phenomenological coefficient tensor is used in a 3- and 2.5-dimensional modeling approach for calculating the fiber orientation. The prediction quality of the simulative fiber orientations is evaluated in comparison to experiments. Depending on the material modeling and validation level, the prediction of the simulated fiber orientation differs in the range between 7.3 and 347.2% averaged deviation significantly. Furthermore, depending on the process–structure coupling and the number of layers over the thickness of the model, the Kullback–Leibner divergence differs in a range between 0.1 and 4.9%. In this context, more layers lead to higher fiber orientation content in the model and improved prediction of the structural dynamics simulation. This is significant for local and slightly for global structural dynamics phenomena regarding the mode shapes and frequency response behavior of simulative and experimental investigations. The investigations prove that the influence of the fiber orientation on the structural dynamics simulation is lower than the influence of the material modeling. With a relative average deviation of 2.8% in the frequency and 38.0% in the amplitude of the frequency response function, it can be proven that high deviations between experimental and simulative fiber orientations can lead to a sufficient prediction of the structural dynamics simulation.
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Potluri, Prasad, Raj Ramgulam, Marco Chilo, and Haseeb Arshad. "Tow-Scale Mechanics for Composite Forming Simulations." Key Engineering Materials 504-506 (February 2012): 255–60. http://dx.doi.org/10.4028/www.scientific.net/kem.504-506.255.
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Abstract. Composites are processed by a variety of forming techniques at both preforming and consolidation stages; ranging from hand draping, diaphragm forming, vacuum infusion to Resin Transfer Molding. During these processes, individual fabric or prepreg layers are subjected to inplane tension and shear, inter-ply shear, transverse compression and out-of-plane bending forces. These forming forces are translated into individual tow-level forces leading to tow deformations. Each tow is subjected to tension, transverse compaction (in the plane of the fabric due to shear and normal to the fabric plane due to consolidation force), bending and torsion. The resulting tow geometry and local fibre volume fractions (within a tow) would have a significant impact on resin flow as well as mechanical properties of the composite. In this paper, we present computational as well as experimental approaches to predicting tow deformations, when subjected to various loading conditions. The test rigs, shown in figure 1, can measure stress-strain behaviour of a tow in bending, torsion and transverse compression respectively. Figure shows buckling of carbon tow – bending stiffness can be computed from the post-buckling behavior. Torsional moments at monotonically increased twist angle were measured using a very sensitive torque sensor. An anvil, nearly same size as a tow, is used to compress a tow (under controlled axial tension) and the cross-sectional shape is computed from the flattened image (recorded using a high resolution camera). A mechanics-based model has been developed to predict tow-scale deformations under transverse compression, tension, bending and torsion modes of deformation. Individual fibres in a tow are modeled as ‘3D elastica’ and a simple inter-fibre friction model has been incorporated. Initially developed for twisted fibre bundles, the elastic-based model works reasonably well for untwisted fibre tows (by assuming an extremely small twist level for convergence). Full paper will present comparison between experimental and theoretical results.
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Switzer, Leonard H., and Daniel J. Klingenberg. "Rheology of sheared flexible fiber suspensions via fiber-level simulations." Journal of Rheology 47, no. 3 (May 2003): 759–78. http://dx.doi.org/10.1122/1.1566034.
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M.N, Jamaludin,, Mohamad, S., Sunar, M.S., Isa, K., Hanifa, R.M., Nasir, F.M., and Shah, S.M. "OpenGL 3D crowd evacuation simulation at universiti tun hussein onn malaysia (UTHM) hostel." Indonesian Journal of Electrical Engineering and Computer Science 16, no. 2 (November 1, 2019): 1034. http://dx.doi.org/10.11591/ijeecs.v16.i2.pp1034-1041.
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<span lang="EN-GB">Crowd simulation is the process of simulating characterized agents or entities using computer application to analyse it in virtual scene or virtual environment. This paper investigates the best route path for agents to act in avoiding the fire hazards with different designated type of stairs in shop lots that were converted to hostel dormitory for students. 3D social force agent’s model and 3D fire hazards were designed in Microsoft Visual Studio C++ software and OpenGL library. A research was conducted using social force model behaviour and were taken by 10 and 15 agents to analyse the time taken to complete the evacuation process. The acceleration produced where it is related with route path taken by agents, interaction forces of agents and interaction forces of wall are the main research system to analyse agents’ behaviour during simulation. Different simulations have been used to determine the best and fastest route taken by agents. In summary, the lower the number of agents, the lower the time allocated by agents to complete the evacuation. Finally, less number of agents using the designated straight stairs gave a lower time to complete evacuation process and reached high level of security to avoid being exposed to fire hazards. </span>
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Patham, Bhaskar, and Xiaosong Huang. "Multiscale Modeling of Residual Stress Development in Continuous Fiber-Reinforced Unidirectional Thick Thermoset Composites." Journal of Composites 2014 (March 24, 2014): 1–17. http://dx.doi.org/10.1155/2014/172560.
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The primary objective of this research is to develop a multiscale simulation framework to arrive at more realistic estimates of cure-induced residual stresses in the vicinity of the fiber-matrix interface in thick thermoset composites. The methodology involves simulations at the part level—employing homogenized rendering of the composite using micromechanics approach—within a finite element framework to obtain part-level temperature and degree-of-cure gradients and strains, and imposition of this information as boundary conditions at the mesoscale simulations, employing microstructural representative volume elements (RVE). A simple implementation of the multiscale framework, involving simulations at the part as well as the RVE levels, is demonstrated in the context of a thick, unidirectional continuous-glass-fiber-reinforced thermoset composite. The trends in the mesoscale residual stresses estimated by employing different RVE-level thermal and thermomechanical boundary conditions—displaying different degrees of coupling between the global and part-level simulations—are then examined. Significant differences are observed in the estimates of mesolevel cure-induced residual stress evolution obtained from simulations with a conventional symmetric RVE and those obtained by employing the multiscale approach involving detailed boundary conditions that realistically account for global thermal and mechanical strain histories.
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Sinchuk, Y., Y. Pannier, M. Gueguen, and M. Gigliotti. "Image-based modeling of moisture-induced swelling and stress in 2D textile composite materials using a global-local approach." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 232, no. 8 (October 25, 2017): 1505–19. http://dx.doi.org/10.1177/0954406217736789.
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The present paper focuses on the employment of a global-local approach for the simulation of moisture-induced swelling and stress in a 2D textile carbon fiber/epoxy matrix composite material. The approach is based on the development of a robust image-based finite element model built starting from X-ray microtomography scans of a repetitive unit cell of the textile material: simulations aim at investigating both the global (sample scale) level and the local micromechanical (interfaces between matrix and fibrous tows, matrix inside a tow) level behaviour. Three models at the different cited scales are first built (ply level model, tow level and fiber level model): then a non-concurrent (node-based) approach is used for coupling the models at different scales. The results of numerical simulation of moisture-induced swelling and stress are discussed, with emphasis on the identification of the most critical zones at which maximal stress values are calculated, at different scales.