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1
Manoj, Greeshma. "Export performance of Indian Textile Industry in the Post Multi Fibre Agreement Regime." Artha - Journal of Social Sciences 13, no. 4 (October 17, 2014): 63. http://dx.doi.org/10.12724/ajss.31.5.
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The Multi Fibre Agreement (MFA) and the quota system which governed the international trade in textiles and clothing came to an end on 1st January, 2005. The quota systems were more restrictive against cotton based fibres, which dominate India’s textile exports. Since India has a natural comparative advantage in cotton and cotton based fibres, abolition of MFA was expected to benefit India’s cotton industry as well as cotton based textiles and clothing sectors. This paper analyses the export performance of Indian textile industry in the post quota regime in terms of different sub sectors of Indian textiles during the period from 1992 to 2012.The entire period of the study is divided into Pre MFA (1992-2004) and Post MFA (2005-2012). Export performance has been examined in terms of annual growth rate and Compound Annual Growth Rate for the period from 1992-2012. The study finds that the textile exports have registered a strong growth rate in the post quota period (2005-2006), increasing from 2.69% in 2004-2005 to 23.14% in 2005-2006. A comparison of the different sectors of the textile export shows that all the sectors recorded an increase in the export values at different phases of the quota removal. If we compare the pre MFA growth (III Phase) and Post MFA growth (IV Phase), there has been a remarkable improvement in the export performance of all the sub sectors. Biggest gainer in the post MFA period is manmade textiles followed by cotton textiles and readymade garments. But India was not able to continue the same momentum in the succeeding years. This clearly indicates that Indian textile industry is facing so many challenges in the post quota regime. Thus, it is imperative to improve the competitiveness of our exports through policy changes, new investment and efficient supply chain management. Keywords: Textiles and clothing, Quota removal, MFA, Export performance, Trend analysis.
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Manoj, Greeshma, and S. Muraleedharan. "Productivity of Indian Textile Industry in the Post Multi Fibre Agreement (MFA) Regime." Asian Review of Social Sciences 8, no. 1 (February 5, 2019): 123–31. http://dx.doi.org/10.51983/arss-2019.8.1.1507.
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The system of bilateral quotas which had governed the international trade in textiles and clothing under the Multi Fibre Agreement came to an end and has been replaced by the Agreement on Textiles and Clothing (ATC) from January 1, 2005. The ATC provided for a progressive elimination of quota in four stages during the transitional period which ended on 2005. This study is an attempt to understand the impact of trade liberalization on the productivity of Indian textile industry. Estimation of labour productivity shows an improvement in the labour productivity during the post MFA period. Analysis of capital productivity reveals that average capital productivity was higher during the pre MFA period compared to post MFA period. Capital intensity estimate reveals that there has been an increase in the capital intensity for all product groups in the post MFA period compared to pre MFA.
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Anand, Chirag, Roger Groves, and Rinze Benedictus. "A Gaussian Beam Based Recursive Stiffness Matrix Model to Simulate Ultrasonic Array Signals from Multi-Layered Media." Sensors 20, no. 16 (August 5, 2020): 4371. http://dx.doi.org/10.3390/s20164371.
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Ultrasonic testing using arrays is becoming widely used to test composite structures in the Aerospace industry. In recent years, the Full Matrix Capture (FMC) technique has been implemented to extract the signals for post-processing to form an image. The inherent anisotropy and the layering of the structure pose challenges for the interpretation of this FMC data. To overcome this challenge, modeling techniques are required that take into account the diffraction caused by finite-size transducers and the response of the structure to these bounded beams. Existing models either homogenize the entire structure, use computationally expensive finite difference time domain (FDTD) methods, or do not consider the shape of the bounded beam, which is used to test such structures. This paper proposes a modeling technique based on combining the Multi-Gaussian beam model with the recursive stiffness matrix method to simulate the FMC signals for layered anisotropic media. The paper provides the steps required for the modeling technique, the extraction of the system efficiency factor, and validation of the model with experimentally determined signals for aluminum as an isotropic material such as aluminum and Carbon Fiber Reinforced Plastic (CFRP) laminate as a layered material. The proposed method is computationally inexpensive, shows good agreement with the experimentally determined FMC data, and enables us to understand the effects of various transducer and material parameters on the extracted FMC signals.
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Dikshit, J. R., P. C. Basak, and Kamal Vagrecha. "Impact of World Trade Organization on Indian Textile Industry." Global Journal of Enterprise Information System 7, no. 1 (March 1, 2015): 35. http://dx.doi.org/10.18311/gjeis/2015/3033.
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<p>No country in the world is self-sufficient. Therefore, there is need to trade with others. Economy was protected from external competition due to licensing system and high level of tariff.</p><p>In early 1990's with the birth of World Trade Organization (WTO) India started the process of liberalization of trade. WTO's objective is to ensure new open world trading system to benefit consumers. The Most Favoured Nation clause of WTO was in clash with the Multi Fibre Agreement (MFA), which placed quantitative restrictions on textile exporting countries. Hence MFA was gradually phased out by December 31, 2004.</p><p>The phasing out of Multi Fibre Agreement (MFA) was expected to result in an increase in the growth of output, efficiency, productivity and competitiveness of the textile sector.</p><p>The impact of abolition of MFA is studied with regard to export of yarn, fabric, and garments during MFA and Post MFA period. It has been concluded from the observations that the export of textile intermediates (i.e. yarn and fabric) and textiles and clothing have increased substantially after the abolition of MFA.</p>
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White, S. C., and P. M. Weaver. "Towards imperfection insensitive buckling response of shell structures-shells with plate-like post-buckled responses." Aeronautical Journal 120, no. 1224 (February 2016): 233–53. http://dx.doi.org/10.1017/aer.2015.14.
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ABSTRACTThe imperfection sensitivity of cylindrical panels under compression loading is shown to be not only reduced but effectively eliminated using stiffness tailoring techniques. Shells are designed with variable angle-tow (VAT) laminae, giving their laminates variable-stiffness properties over the surface co-ordinates. By employing an asymptotic model of the non-linear shell behaviour and a genetic algorithm, the post-buckling stability was maximised with respect to the VAT design variables. Results for optimised straight-fibre and VAT shells are presented in comparison with quasi-isotropic designs. In the straight-fibre case, small improvements in the post-buckling stability are shown to be possible but at the expense of the buckling load. In the VAT case, on the other hand, considerable improvements in the post-buckling stability are obtained and drops in axial stiffness and load associated with buckling are reduced to negligible levels. The improvements are shown to be a result of a benign membrane stress distribution prior to buckling and a localisation of the buckling mode. The asymptotic results are compared with non-linear finite-element analyses and are found to be in good agreement. Potential future multi-objective optimisation studies are discussed.
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Belfatto, Antonella, Alessandro Scano, Andrea Chiavenna, Alfonso Mastropietro, Simona Mrakic-Sposta, Simone Pittaccio, Lorenzo Molinari Tosatti, Franco Molteni, and Giovanna Rizzo. "A Multiparameter Approach to Evaluate Post-Stroke Patients: An Application on Robotic Rehabilitation." Applied Sciences 8, no. 11 (November 14, 2018): 2248. http://dx.doi.org/10.3390/app8112248.
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Multidomain instrumental evaluation of post-stroke chronic patients, coupled with standard clinical assessments, has rarely been exploited in the literature. Such an approach may be valuable to provide comprehensive insight regarding patients’ status, as well as orienting the rehabilitation therapies. Therefore, we propose a multidomain analysis including clinically compliant methods as electroencephalography (EEG), electromyography (EMG), kinematics, and clinical scales. The framework of upper-limb robot-assisted rehabilitation is selected as a challenging and promising scenario to test the multi-parameter evaluation, with the aim to assess whether and in which domains modifications may take place. Instrumental recordings and clinical scales were administered before and after a month of intensive robotic therapy of the impaired upper limb, on five post-stroke chronic hemiparetic patients. After therapy, all patients showed clinical improvement and presented pre/post modifications in one or several of the other domains as well. All patients performed the motor task in a smoother way; two of them appeared to change their muscle synergies activation strategies, and most subjects showed variations in their brain activity, both in the ipsi- and contralateral hemispheres. Changes highlighted by the new multiparametric instrumental approach suggest a recovery trend in agreement with clinical scales. In addition, by jointly demonstrating lateralization of brain activations, changes in muscle recruitment and the execution of smoother trajectories, the new approach may help distinguish between true functional recovery and the adoption of suboptimal compensatory strategies. In the light of these premises, the multi-domain approach may allow a finer patient characterization, providing a deeper insight into the mechanisms underlying the relearning procedure and the level (neuro/muscular) at which it occurred, at a relatively low expenditure. The role of this quantitative description in defining a personalized treatment strategy is of great interest and should be addressed in future studies.
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Shihab, Muchsin, and Sudhir K. Jain. "The Preparedness of the Indonesian Garment Exporters in the Post-MFA Scenario: An Analysis from the Survey." Gadjah Mada International Journal of Business 6, no. 3 (September 12, 2004): 383. http://dx.doi.org/10.22146/gamaijb.5555.
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The clothing or garments industry has developed rapidly during the past some decades and has contributed to the economic growth of many nations, both developed and developing countries. This industry has been very much regulated by many bilateral agreements such as Multi Fiber Arrangement (MFA), a quota arrangement made by the importing countries. As MFA (quota regime) comes to an end by 2005 and integrates into the WTO regime, it will bring opportunities to highly competitive and proactive garment exporting countries whereas the challenges will be faced more by the less competitive countries. Issues related to environment and social compliance, technology requirements etc. have been brought into surface by the importing countries, which may worsen the condition. Under the above scenario, it is imperative that certain proactive measures be taken. Thus, the broad objective of this study is to analyze the response of the garment exporters from Indonesia towards the emerging issues related to environmental and social compliance, technology requirements etc. The present study is a questionnaire-based study. The samples have been selected from the Directories of largest exporters in the country. With reminders and persuasion, the final number of useable responses has been 115 Indonesian garment exporters. Seven factors of the emerging issues were identified by using factor analysis. In addition, factors of competitiveness, and the strategies adopted by the exporters have also been analyzed. The findings show that the overall perceptions of the Indonesia garment exporters indicate that Indonesia is less competitive as compared to other competing countries.
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Abu Hatab, Assem. "“Made in China”: the displacement effect of China on Egyptian textile exports." Journal of Agribusiness in Developing and Emerging Economies 7, no. 2 (August 21, 2017): 99–114. http://dx.doi.org/10.1108/jadee-01-2015-0005.
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Purpose A growing number of studies indicate that the export growth of China’s textiles poses serious threats to many developing countries. The purpose of this paper is to empirically measure the extent to which the export growth of Chinese textiles has come at the expense of Egyptian textiles exports in third importing markets. Design/methodology/approach To measure this effect, an augmented gravity model equation was estimated using annual data covering the period 1994-2012 on Egyptian and Chinese textile exports to traditional importers of Egyptian textiles. Findings The empirical results suggest that Egyptian textiles are vulnerable to competitive threat posed by China, especially in the EU and US markets. In contact, Egyptian textile exports have moved hand-in-hand with Chinese textile exports to Asian markets. Moreover, the results suggest that the expiration of the Multi-fiber Agreement in 2005 has exposed Egyptian textile exports to fierce completion with China and resulted in declines in Egypt’s textile exports to the world. However, the trade agreements that Egypt signed with the world countries have given Egypt a competitive edge in major importing regions and mitigated the negative impacts of China in the post-2005 period. Finally, the paper argues that unless Egypt adjusts and develops its textile sector in response to such heightened competition from China, Egyptian textile exports undoubtedly would further be negatively impacted. Research limitations/implications In this study, Egypt’s textile products are aggregated to one group and analyzed as a whole, “textile exports.” Further research using a more disaggregated level of data would offer deeper insights into the impacts of China on Egyptian textile exports. Originality/value The contribution of this paper is twofold: first, it adds to the growing literature aiming to understand the impacts of China’s growth on developing countries exports by providing a case study of Egyptian textile export sector. Second, the policy implications drawn from this paper could be useful to Egyptian policy makers and stakeholders to address and respond to the competitiveness challenges posed by China to the Egyptian textile industry.
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Xue, Jian Xing, Xue Dong Gu, Li Qiang Song, Qi Ming Wang, Xue Bin Zhai, and Bao Qing Zhao. "Research on Catenary Characteristics of FAST Tie-Down Cable and its Effect on Actuator and Joint." Advanced Materials Research 875-877 (February 2014): 664–70. http://dx.doi.org/10.4028/www.scientific.net/amr.875-877.664.
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To study catenary characteristics of FAST (Five-hundred-meter Aperture Spherical radio Telescope) tie-down cable, this paper establishes tie-down cable equilibrium differential equation and cable length formula based on catenary theory, analyzes numerical simulation of multi-segment bar element method, and designs an experimental scheme. Taking 1×7 Ø12.7steel cable and Ø10 CFRP (Carbon Fiber Reinforced Polymer) cable for example, we can obtain three results respectively through manners mentioned above, and the agreement among them is excellent. Meanwhile, difference between results and elastic deformation of no-weight cable is not so big that catenary of two cables can be negligible. Further research shows that cable length is more sensitive to catenary than horizontal angle; cable longer deformation will benefit actuator to meet position precision effortlessly, however, stroke and velocity of actuator will increase and initial tension displacement of tie-down cable decrease correspondingly, this alteration should be compensated during reflector surface measuring and controlling; due to chord-tangent angle and tangential force is less than 1.28°and 241.4N, catenary effect on joint pose is weaker; generally speaking, CFRP cable has less catenary problem than steel cable, better mechanics characteristics, but bigger stroke and velocity for actuator and smaller initial tension displacement for tie-down cable. The research will provide references for design of tie-down cable, actuator, joint, and reflector measurement and control.
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Xiao, Zhi Gang, Yao Jiang, and Xiao Xiao. "A Cascaded Multi- and Single-Mode Fiber Transporting for Laser Beam." Applied Mechanics and Materials 109 (October 2011): 222–27. http://dx.doi.org/10.4028/www.scientific.net/amm.109.222.
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A model to calculate the butt-joint coupling efficiency between a multi-mode fiber to a single-mode fiber is presented based on a mode field coupling theory. The dependence of the coupling efficiency between the multi- and single-mode fibers on the core radius of the multi-mode fiber is investigated. A experiment is conducted with 532nm laser to measure the butt joint coupling efficiency of a multi-mode fiber to a single-mode fiber. Good agreement is obtained between the experimental results and the theoretical predictions. A cascaded multi- and single-mode fiber relay system is proposed to transport a laser beam with high power and good beam quality.
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Moon, Chang Kwon, and Ki Woo Nam. "Study on 2-D Multi-Fiber Arrange Model Composites." Key Engineering Materials 297-300 (November 2005): 219–24. http://dx.doi.org/10.4028/www.scientific.net/kem.297-300.219.
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The effect of interfiber distance on the interfacial properties in two dimensional multi-Eglass fiber/epoxy resin composites has been investigated using fragmentation test. In additions, the effect of the fiber surface treatment on the interfacial properties has been studied. We found that the interfacial shear strength decreased with the decreasing of the interfiber distance at the range of under 50µm and the extent of the decreasing was more serious as the increasing of the number of adjacent fiber. This is probably that the interface between the fiber and the resin was damaged by the adjacent fiber breaks and the damage increased with closing the interfiber spacing and the number of adjacent fiber. We can guess from this interfacial shear strength in real composites is much smaller than that of multi-fiber fragmentation sample with touched fiber. It was seen that the interfacial shear strengths saturated when the interfiber distance was over 50µm, the ones were saturated regardless of fiber surface treatment and the ones were in close agreement with those of the single fiber fragmentation test. Finally, the interfacial shear strength evaluated using two dimensional fragmentation tests are shown as real values in-site regardless of fiber surface treatment, interfiber distance and existing of matrix cracks.
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Eleftherios, Tsivolas, Leonidas N. Gergidis, and Alkiviadis S. Paipetis. "Computational Multi-Scale Modelling of Fiber-Reinforced Composite Materials." Key Engineering Materials 827 (December 2019): 263–68. http://dx.doi.org/10.4028/www.scientific.net/kem.827.263.
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A cross-ply fiber-reinforced composite in uniaxial tension is modelled using a mesoscale and a micro-scale approach comparing the results from both the analyses. The use of multi-scale modelling gives directly the macroscopic constitutive behaviour of the structures based on its microscopically heterogeneous representative volume element (RVE). In the meso-scale approach the material of each layer is modelled as a homogeneous transversely isotropic material whose properties resulted from a numerical homogenization analysis. One of the main advantages of micro-scale modelling is the ability to simulate damage mechanisms such as matrix cracking, delaminations of the matrix-fiber interface and fibre-damage. In the first part of this study, analytical and numerical homogenization schemes are compared. RVEs of continuous fibre and short-fibre reinforced composites are created, homogenized numerically and compared with the widespread analytical scheme of Mori-Tanaka based on Eshelby’s solution of the single inclusion problem. In the second part, results’ comparison between the simulations of both scales is performed. In the meso-scale model stochasticity has been introduced, assigning interfacial strength following a normal distribution, in order to predict cracking initiation, propagation and saturation at the matrix material. The stresses at the crack tips are compared with the stress fields around the cracks from the micro-scale analysis and the results are in good agreement.
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Crossa Niell, Mateo. "Multi‐fiber agreement 15 years later: Degraded working conditions in the Honduran Garment Maquiladora Industry †." Journal of Labor and Society 23, no. 3 (August 11, 2020): 317–35. http://dx.doi.org/10.1111/wusa.12480.
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Grujicic, M., JS Snipes, and S. Ramaswami. "Multi-scale computational analysis of the nano-indentation and nano-scratch testing of Kevlar® 49 single fibers." Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 232, no. 6 (February 27, 2016): 495–513. http://dx.doi.org/10.1177/1464420716635851.
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To carry out virtual nano-indentation and nano-scratch Kevlar® 49 single-fiber tests, a multi-scale computational framework has been developed and employed. Such tests are generally conducted to determine fiber local properties, as well as to provide some insight into the interaction of hard nano-particles with the fibers. The Kevlar® fabric-based soft armor is infused with these nano-particles for improved ballistic resistance, and tip geometry of the nano-indentation/-scratch probes is selected to match nano-particle size and geometry. Due to the fact that Kevlar® 49 fibers (typical diameter 12 µm) are effectively assemblies of parallel fibrils (typical diameter 100–300 nm), while atomic bond length in Kevlar® fibers is of the order of 0.2 nm, a continuum-level finite-element framework has been developed. However, to more accurately account for some of the key aspects of the fiber-material constitutive behavior, e.g. inter-fibril cohesion, the continuum-level computational analysis has been supplemented with atomic-level molecular-statics/-dynamics calculations. In good agreement with their experimental counterparts, the results obtained revealed that the extent of participation of different fibril-deformation modes (e.g. transverse compression, inter-fibril shear, axial tension, axial tensile fracture, fibrillation, axial compression, buckling and pile-up formation ahead of the nano-scratch probe, etc.) is a function of the indentation/scratch depth. Also, a relatively good agreement was obtained between the computed and experimentally measured nano-indentation forces/energies for both shallow and deep indentations, and for the nano-scratch forces/energies, but only for shorter scratch lengths. At longer scratch lengths, the “short-fiber” effects cause the computation/experiment agreement to worsen.
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Papadimitriou, Lamprini, Ian P. Holman, Robert Dunford, and Paula A. Harrison. "Trade-offs are unavoidable in multi-objective adaptation even in a post-Paris Agreement world." Science of The Total Environment 696 (December 2019): 134027. http://dx.doi.org/10.1016/j.scitotenv.2019.134027.
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Ha, Sung Kyu, Lei Xu, Chao Zhao, and Matthias DeMonte. "Progressive failure prediction of short fiber reinforced composites using a multi-scale approach." Journal of Composite Materials 52, no. 27 (April 22, 2018): 3785–801. http://dx.doi.org/10.1177/0021998318770252.
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A hybrid multi-scale approach combining a virtual mesoscale volume element (representative volume element) and a microscale finite element representative unit cell is developed, for progressive failure prediction of short fiber reinforced composites. The representative volume element represents the fiber orientation and distribution of the whole composites, from which the global mechanical behavior can be estimated. The representative unit cell captures the local mechanical response of each short fiber by transforming global strains to local strains. The constituent strains of the fiber, matrix, and interface are calculated from local strains using representative unit cell. Correlations between mesoscale local strains and microscale constituent strains are established using strain amplification factors. After computing microscale stresses, a progressive damage model is employed to determine the damage status of all constituents. A homogenization method is employed to eliminate damage localization in the matrix and interface. The predicted stress–strain curves are compared with experimental results, and good agreement is also achieved.
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Weng, Siming, Pei Yuan, Wei Zhuang, Dongliang Zhang, Fei Luo, and Lianqing Zhu. "SOI-Based Multi-Channel AWG with Fiber Bragg Grating Sensing Interrogation System." Photonics 8, no. 6 (June 10, 2021): 214. http://dx.doi.org/10.3390/photonics8060214.
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For the development of minimized and high-rate photonic-integrated fiber Bragg grating interrogation (FBGI) systems, arrayed waveguide grating (AWG) has been widely used as one of the critical components. In this paper, we present an 8-channel SOI-based AWG for a photonic integrated FBG interrogation microsystem. The channel spacing of the AWG is designed to be 3 nm to meet a high-dynamic-range demodulation requirement. The core size of the fabricated AWG is about 335 × 335 μm2. The simulation results and experimental results are in high agreement, showing that AWG has a fine transmission spectrum with crosstalk below −16 dB, nonuniformity below 0.4 dB, insertion loss below −6.35 dB, 3 dB bandwidth about 1.3 nm and 10 dB bandwidth of 2.3 nm. The proposed AWG can be applied perfectly to the SOI-based AWG demodulation microsystem, exhibiting a large dynamic range of 1.2 nm, the resolution for measurements is 1.27 pm and a high accuracy of 20.6 pm.
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Asgarian, B., A. A. Aghakouchak, and R. G. Bea. "Nonlinear Analysis of Jacket-Type Offshore Platforms Using Fiber Elements." Journal of Offshore Mechanics and Arctic Engineering 128, no. 3 (January 12, 2006): 224–32. http://dx.doi.org/10.1115/1.2185678.
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A nonlinear fiber element for analysis of jacket type offshore structures is formulated and implemented in the nonlinear program DRAIN-3DX. This element can be used for modeling the nonlinear behavior of both strut and portal members. The element predicts buckling load and post buckling behavior of strut members accurately. It also produces fairly accurate results for yield load and post yield behavior of portal members. This element is verified using the experimental data for individual strut and portal members subjected to cyclic displacements. The element is then used to predict nonlinear behavior of two tested X-braced jackets made of tubular members under cyclic lateral displacement. The results are in good agreement with experiments and the results of other analytical models in terms of frame hysteretic behavior, energy dissipation, buckling load, load-deformation curve, strength and stiffness degradation.
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Lin, Samuel I.-En. "Tunable Athermal Multi-FBG Package Using a Bending Bimetal Structure." Journal of Electronic Packaging 124, no. 1 (July 7, 2000): 54–59. http://dx.doi.org/10.1115/1.1414135.
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The Fiber Bragg Gratings (FBGs) written by ultraviolet light into the core of an optical fiber have developed into a critical component for many applications in the fiber-optic communication system. A stable temperature compensation mechanism is essential to the successful usage of FBG-based devices. In this paper, the bimetal-based temperature-compensating package with tunable mechanism was developed. Such a tunable mechanism serves as prestress and post-tuning mechanisms of fixture in order to obtain a predetermined central wavelength. With the aid of developed experimental procedure, this compact and easily manufactured package can achieve temperature coefficient of 8.3×10−4 nm/°C in the temperature range from −40°C to 80°C. The same package can also be used for multi-FBG applications.
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ERKAN, Birol, and Elif Tuğçe BOZDUMAN. "How did the multi-fiber agreement affect the level of specialization in the textile sector of the countries?" Tekstil ve Mühendis 27, no. 120 (December 30, 2020): 283–91. http://dx.doi.org/10.7216/1300759920202712008.
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This paper aims to reveal the effects of the Multi-Fibre Agreement (MFA), which determines the course of the textile trade and the global competition on countries' levels of specialization. In this perspective, we analyze the levels of specialization (competition) of the 10 countries whose exports were the highest in the sector before and after the complete abolition of quotas in a comparatively. In the analyses, we use the Index of Contribution to Trade Balance (ICBT), the Export-Import Ratio Index (EIRI) and the Michaely Index (MI) to measure the progress of countries' level of specialization in the sector by years. All of these indices indicate that the highest levels of specialization in the sector were Pakistan, India and Turkey before the end of the MFA. After 2005, when quotas were completely eliminated, China and Hong Kong increased their level of expertise in the sector and separated positively from other countries. In this context, China achieved a global competitive advantage in the sector, especially with high level of specialization.
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Asgarian, B., A. A. Aghakouchack, and R. G. Bea. "Inelastic Postbuckling and Cyclic Behavior of Tubular Braces." Journal of Offshore Mechanics and Arctic Engineering 127, no. 3 (February 18, 2005): 256–62. http://dx.doi.org/10.1115/1.1904637.
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A nonlinear fiber element for the simulation of buckling, post buckling, and hysteric responses of tubular struts is formulated and implemented in the nonlinear program DRAIN-3DX. In this element both material and geometric nonlinearities are considered. The element is applied to simulate post buckling and hysteric response of pinned and fixed tubular struts subjected to cyclic loading. The results are in good agreement with available results, i.e., experiment and other analytical models data in terms of buckling load, load-deformation curve, strength, and stiffness degradation.
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Lou, Dong, Zainah Ibrahim, and Zubaidah Ismail. "Monitoring of Curing Temperature of Early-Age Cement Paste Using Biconical Tapered Fiber Sensor." Advanced Materials Research 250-253 (May 2011): 3549–53. http://dx.doi.org/10.4028/www.scientific.net/amr.250-253.3549.
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In this paper, a biconical tapered fiber sensor is applied to monitor the temperature of cement paste during curing process. A simple sensing principle of the proposed sensor is presented by analyzing the V-number of leaky rays. An experimental is carried out by tapering the plastic multi-mode step-index fiber to measure the temperature of the cement paste. The numerical result shows that the V-number of leaky ray is increasing with the raised in temperature. The experimental results are in agreement with the results from the theoretical analysis.
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MARK, ANDREAS, ANTON BERCE, ROBERT SANDBOGE, FREDRIK EDELVIK, ERIK GLATT, STEFAN RIEF, ANDREAS WIEGMANN, et al. "Multi-scale simulation of paperboard edge wicking using a fiber-resolving virtual paper model." June 2012 11, no. 6 (July 1, 2012): 9–16. http://dx.doi.org/10.32964/tj11.6.9.
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When liquid packaging board is made aseptic in the filling machine, the unsealed edges of the board are exposed to hydrogen peroxide. A high level of liquid penetration may lead to aesthetic as well as functional defects. The ability to make a priori predictions about the edge wicking properties of a certain paperboard material is therefore of great interest to the paper industry, as well as to packaging manufacturers. In this paper, a multi-scale framework is proposed that allows for detailed simulation of the edge wicking process. On the fiber micro-scale, virtual paper models are generated based on input from tomographic and scanning electron microscope (SEM) images. A pore morphology method is used to calculate capillary pressure curves, and on the active pores, one-phase flow simulations are performed for relative permeabilities. The results as functions of saturation and porosity are stored in a database. The database is used as input for two-phase flow simulations on the paper macro-scale. The resulting fluid penetration is validated against pressurized edge wick measurements on paper lab sheets with very good agreement. The proposed multi-scale approach can be used to increase the understanding of how edge wicking in paperboard packages depends on the micro-structure.
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Beese, W. J., and J. T. Arnott. "Montane Alternative Silvicultural Systems (MASS): Establishing and managing a multi-disciplinary, multi-partner research site." Forestry Chronicle 75, no. 3 (June 1, 1999): 413–16. http://dx.doi.org/10.5558/tfc75413-3.
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The Montane Alternative Silvicultural Systems (MASS) study was established on Vancouver Island, B.C. to develop operationally feasible and ecologically sustainable silvicultural systems in old-growth forests. The project addresses regeneration, biodiversity and aesthetic concerns over clearcutting at high elevations. Over twenty integrated studies are examining the biological and economic consequences of shelterwood, small patch clearcut, dispersed green tree retention and clearcut alternatives. Planning and pre-harvest studies began two years before the 1993 harvesting. The Forest Engineering Research Institute of Canada (FERIC) documented the cost and feasibility of harvesting. Post-harvest studies have been underway for five years with funding by the Canada-B.C. Forest Resource Development Agreement (ERDA II), Forest Renewal BC (FRBC), Industry Canada and project cooperators. There are numerous challenges associated with establishing and managing a multi-disciplinary, long-term research site with multiple partners. This paper discusses the administrative aspects of integrated research based on our experience with the MASS project. Key words: research cooperative, silvicultural systems, old-growth forests
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Yousefi, Behrooz, Mohammad Reza Esfahani, and Mohammadreza Tavakkolizadeh. "A multi-fiber approach with directional stiffness matrix in reinforced concrete structures." Engineering Computations 37, no. 7 (March 23, 2020): 2411–37. http://dx.doi.org/10.1108/ec-09-2019-0424.
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Purpose This paper aims to develop a new multi-fiber element for predicting the structural behavior of planar-reinforced concrete (RC) members. Design/methodology/approach In this work, an exact multi-directional stiffness matrix is analytically derived based on the post-cracking bond-slip interaction between concrete and steel bars. The approach is also extended for large displacement analysis using Green–Lagrange finite strain tensor. In the proposed formulation, the weak form of governed differential equations is approximated by a trial-function expansion based on a finite strain-description and an additional degree of freedom for steel bars. Findings The findings provide a realistic description of cracking in the concrete structure. Numerical studies are conducted to examine the accuracy of the suggested approach and its capability to predict fairly complex responses of RC models. The findings prove that the proposed element can evaluate local and global responses of RC members, and it can be used as a reliable tool to reflect bond-slip effects in large displacement level. This leads to a robust and precise model for non-linear analysis of RC structures. Originality/value The methodology is capable of simulating coupled inelastic shear-flexural behavior of RC members through local stress field theory and Timoshenko beam model.
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Kim, Hyun Chul, Sang Eui Lee, Chun Gon Kim, and Jung Ju Lee. "Mechanical Improvement of Multi-Walled Carbon Nanotube/Poly (Methyl Methacrylate) Composites." Key Engineering Materials 297-300 (November 2005): 2545–50. http://dx.doi.org/10.4028/www.scientific.net/kem.297-300.2545.
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Multi-walled carbon nanotube (MWNT)/poly (methyl methacrylate) composites were fabricated with the variation of the concentration rate of nanotubes by the solution casting. SEM images showed that the nanotubes were dispersed well throughout PMMA. Assuming that MWNTs in MWNT/PMMA composites were randomly oriented, the Tsai-Pagano equation, which can give the moduli of short fiber reinforced composites, was used to evaluate that of the MWNT/PMMA composite. For investigating mechanical properties of the MWNT/PMMA composite, tensile loading tests were performed, varying the concentration rate of the MWNTs. For each concentration rate of the MWNTs, at least 5 specimens of MWNT/PMMA composites were made and tested. As the concentration rate of the MWNTs increased from 0 to 0.15wt%, tensile strength and modulus of the MWNT/PMMA composites were improved by about 20% and 32%, respectively. However, the experimental results were not in agreement with what we estimated. Here are two reasons supposed. First, the MWNTs used in this research were not stretched straightly but entangled. It means that MWNTs cannot be assumed to be short fibers. Second, the concentration rate of the MWNTs is too small to be considered as short fiber composites.
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Morel, E., K. Santamaria, M. Perrier, S. R. Guiot, and B. Tartakovsky. "Multi-wavelength fluorometry for anaerobic digestion process monitoring." Water Science and Technology 52, no. 1-2 (July 1, 2005): 465–71. http://dx.doi.org/10.2166/wst.2005.0554.
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Applicability of multi-wavelength fluorometry for anaerobic digestion process monitoring was investigated in a 3.5 L upflow anaerobic sludge bed (UASB) lab-scale reactor. Both off-line and on-line monitoring of key process parameters was tested. Off-line emission spectra were measured at an angle of 90° to the excitation beam using a cuvette. On-line measurements were carried out using a fiber optic probe in the external recirculation line of the digester. Fluorescence spectra were correlated to available analytical measurements to obtain partial least square regression models. An independent set of measurements was used to validate the regression models. Model estimations showed reasonable agreement with analytical measurements with multiple determination coefficients (R2) between 0.6 and 0.95. Results showed that off-line fluorescence measurements can be used for fast estimation of anaerobic digestor effluent quality. At the same time, the on-line implementation of multi-wavelength fluorescence measurements can be used for real-time process monitoring and, potentially, for on-line process control.
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Yang, Taolue, Huaping Wang, and Xingzhe Wang. "Strain Transfer Characteristics of Multi-Layer Optical Fiber Sensors with Temperature-Dependent Properties at Low Temperature." Sensors 21, no. 2 (January 12, 2021): 495. http://dx.doi.org/10.3390/s21020495.
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Optical fiber sensors have been potentially expected to apply in the extreme environment for their advantages of measurement in a large temperature range. The packaging measure which makes the strain sensing fiber survive in these harsh conditions will commonly introduce inevitable strain transfer errors. In this paper, the strain transfer characteristics of a multi-layer optical fiber sensing structure working at cryogenic environment with temperature gradients have been investigated theoretically. A generalized three-layer shear lag model incorporating with temperature-dependent properties of layers was developed. The strain transfer relationship between the optical fiber core and the matrix has been derived in form of a second-order ordinary differential equation (ODE) with variable coefficients, where the Young’s modulus and the coefficients of thermal expansion (CTE) are considered as functions of temperature. The strain transfer characteristics of the optical sensing structure were captured by solving the ODE boundary problems for cryogenic temperature loads. Case studies of the cooling process from room temperature to some certain low temperatures and gradient temperature loads for different low-temperature zones were addressed. The results showed that different temperature load configurations cause different strain transfer error features which can be described by the proposed model. The protective layer always plays a main role, and the optimization geometrical parameters should be carefully designed. To verify the theoretical predictions, an experiment study on the thermal strain measurement of an aluminum bar with optical fiber sensors was conducted. LUNA ODiSI 6100 integrator was used to measure the Rayleigh backscattering spectra shift of the optical fiber at a uniform temperature and a gradient temperature under liquid nitrogen temperature zone, and a reasonable agreement with the theory was presented.
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DorMohammadi, S., M. Repupilli, D. Huang, F. Abdi, Y. Song, U. Gandhi, and M. Lee. "Crush simulation of automotive chopped fiber composite structures by de-homogenization multi-scale computational method." Journal of Composite Materials 52, no. 28 (July 13, 2018): 3935–59. http://dx.doi.org/10.1177/0021998318772012.
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A de-homogenization multi-scale computational method is proposed for the virtual performance simulation of chopped fibers composites under crush loadings. The novel approach led to the development of a multi-scale material characterization procedure for composite systems, comprising of: (1) chopped fibers homogenization based on the Eshelby and Mori–Tanaka inclusion theories, (2) orientation tensor stiffness averaging technique, (3) micro- and macro-mechanics damage and failure theories, and (4) crush resistance evaluation, as a part of the durability and damage tolerance analysis. The chopped fibers material model developed in this work is then employed in a finite element analysis, interfaced with a multi-scale progressive failure technique to track damage and fracture evolution. Comparison of the simulation results obtained for two tubes, manufactured by injection and compression molding respectively, shows good agreement with the crush test data within 10% accuracy. The proposed de-homogenization method offers a superior load resistance prediction over commercially available techniques. Furthermore, the implementation of the proposed approach in our in-house software provides traceable damage evolution and visualization of the contributing failure mechanisms, valuable sources for the design and development of new composite structures.
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Georgantzinos, Stelios K., Panagiotis A. Antoniou, and Stylianos I. Markolefas. "A Multi-Scale Method for Designing Hybrid Fiber-Reinforced Composite Drive Shafts with Carbon Nanotube Inclusions." Journal of Composites Science 5, no. 6 (June 10, 2021): 157. http://dx.doi.org/10.3390/jcs5060157.
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In this paper, the modal and linear buckling analysis of a laminated composite drive shaft reinforced by 11 multi-walled carbon nanotubes (MWCNTs) was carried out using an analytical approach, as well as the finite element method (FEM). The theoretical model is based on classical laminated theory (CLT). The fundamental frequency and the critical buckling torque were determined for different fiber orientation angles. The Halpin–Tsai model was employed to calculate the elastic modulus of composites having randomly oriented nanotubes. The effect of various carbon nanotube (CNT) volume fractions in the epoxy resin matrix on the material properties of unidirectional composite laminas was also analyzed. The fundamental frequency and the critical buckling torque obtained by the finite element analysis and the analytical method for different fiber orientation angles were in good agreement with each other. The results were verified with data available in the open literature, where possible. For the first time in the literature, the influence of CNT fillers on various composite drive shaft design parameters such as the fundamental frequency, critical speed, and critical buckling torque of a hybrid fiber-reinforced composite drive shaft is finally predicted.
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Gough, Christopher R., Ashley Rivera-Galletti, Darrel A. Cowan, David Salas-de la Cruz, and Xiao Hu. "Protein and Polysaccharide-Based Fiber Materials Generated from Ionic Liquids: A Review." Molecules 25, no. 15 (July 24, 2020): 3362. http://dx.doi.org/10.3390/molecules25153362.
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Natural biomacromolecules such as structural proteins and polysaccharides are composed of the basic building blocks of life: amino acids and carbohydrates. Understanding their molecular structure, self-assembly and interaction in solvents such as ionic liquids (ILs) is critical for unleashing a flora of new materials, revolutionizing the way we fabricate multi-structural and multi-functional systems with tunable physicochemical properties. Ionic liquids are superior to organic solvents because they do not produce unwanted by-products and are considered green substitutes because of their reusability. In addition, they will significantly improve the miscibility of biopolymers with other materials while maintaining the mechanical properties of the biopolymer in the final product. Understanding and controlling the physicochemical properties of biopolymers in ionic liquids matrices will be crucial for progress leading to the ability to fabricate robust multi-level structural 1D fiber materials. It will also help to predict the relationship between fiber conformation and protein secondary structures or carbohydrate crystallinity, thus creating potential applications for cell growth signaling, ionic conductivity, liquid diffusion and thermal conductivity, and several applications in biomedicine and environmental science. This will also enable the regeneration of biopolymer composite fiber materials with useful functionalities and customizable options critical for additive manufacturing. The specific capabilities of these fiber materials have been shown to vary based on their fabrication methods including electrospinning and post-treatments. This review serves to provide basic knowledge of these commonly utilized protein and polysaccharide biopolymers and their fiber fabrication methods from various ionic liquids, as well as the effect of post-treatments on these fiber materials and their applications in biomedical and pharmaceutical research, wound healing, environmental filters and sustainable and green chemistry research.
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Truong, Gia Toai, Hai Van Tran, and Kyoung-Kyu Choi. "Investigation on Mode I Fracture Toughness of Woven Carbon Fiber-Reinforced Polymer Composites Incorporating Nanomaterials." Polymers 12, no. 11 (October 28, 2020): 2512. http://dx.doi.org/10.3390/polym12112512.
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This study experimentally investigated the effects of nanomaterials and interface fiber angle on the mode I fracture toughness of woven carbon fiber-reinforced polymer (CFRP) composites. Three different types of nanomaterials were used: COOH-functionalized short multi-walled carbon nanotubes (S-MWCNT-COOH), multi-walled carbon nanotubes (MWCNTs), and graphene nanoplatelets (GnPs). Double cantilever beam specimens were composed of 12 woven carbon fiber fabrics with/without 1 wt% nanomaterials, and were manufactured using the hand lay-up method. Furthermore, two different stacking sequence series were used; the first series comprised only on-axis carbon-fiber fabrics (0° or 90°), and the second series comprised both on- and off-axis carbon-fiber fabrics (0° or 90° and ±45°). The test results showed that adding S-MWCNT-COOH, MWCNTs, and GnPs significantly increased the mode I fracture toughness of the CFRP composites for both the stacking sequence series. Moreover, the specimens that used only on-axis carbon fiber fabrics exhibited higher fracture toughness values than those of the specimens that used on- and off-axis carbon fiber fabrics together. In addition, an empirical model was established to predict the fracture toughness of the CFRP composites with nanomaterials by using on- and off-axis carbon fiber fabrics together, and the prediction results showed a good agreement with the experimental results.
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Mandrekar, S. J., M. M. Huschka, P. L. Schaefer, J. R. Jett, A. A. Adjei, and J. A. Sloan. "What is the value added of patient reported outcomes relative to physician rated symptom assessments?" Journal of Clinical Oncology 24, no. 18_suppl (June 20, 2006): 8580. http://dx.doi.org/10.1200/jco.2006.24.18_suppl.8580.
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8580 Background: This pooled analysis examined the relationship between single-item and multiple-item quality of life (QOL) measures and assessed the agreement between changes in QOL and patient-reported adverse events (AE). Methods: Data from six lung cancer clinical trials involving 358 patients were pooled. All trials incorporated the UNISCALE and one of three multiple-item assessments: the Functional Assessment for Cancer Therapy-Lung, the Lung Cancer Symptom Scale, or the Symptom Distress Scale. A clinically significant decline (CSD) in QOL was defined as a 10-point drop from baseline. A CSD in AE was defined as a change from ≤ grade 2 at baseline to ≥ grade 3 post-baseline. Spearman rank correlations and Bland-Altman approach were used to assess agreement. The Kaplan-Meier method was used to evaluate the time to the first occurrence of a severe (grade 3+) AE and first CSD in QOL. Results: Correlations between the UNISCALE and multi-item assessments were modest (rho=0.49–0.66). At least one 10-point decline in the UNISCALE and multi-item assessments were reported by 58% and 40% respectively. At least one severe AE was reported in 44% of patients post-baseline. The percent agreement between experiencing a severe AE and a CSD in QOL was 49% and 59% for UNISCALE and the multi-item tools. For individual AE, the percent agreement between a CSD in AE and a CSD in QOL ranged from 37% to 50% for UNISCALE and 44% to 69% for the multi-item tools. The median time to the first CSD in QOL for UNISCALE and multi-item tools was 67 and 142 days respectively. The median time to the first occurrence of a severe AE was 304 days. Conclusions: QOL and AE provide quantifiably different information. A 10-point decline in QOL occurs earlier than CTC AE reporting. Patient reported outcomes may be more sensitive in identifying clinically relevant problems than physician rated symptom assessments. No significant financial relationships to disclose.
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Khanna, Sanjeev K., Marius D. Ellingsen, and Robb M. Winter. "Investigation of Fracture in Transparent Glass Fiber Reinforced Polymer Composites Using Photoelasticity." Journal of Engineering Materials and Technology 126, no. 1 (January 1, 2004): 1–7. http://dx.doi.org/10.1115/1.1631022.
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Fiber-reinforced plastic composite materials are being widely used in a variety of load bearing and high-performance structures. Reliable use and optimum design requires accurate methods for predicting their fracture behavior, among other things. Fiber reinforced plastic composites are generally opaque and hence experimental fracture mechanics studies utilize surface measurements or post-fracture analysis. Hence quality transparent glass cloth reinforced polyester composites have been fabricated and transmission photoelasticity used to investigate quasi-static Mode-I fracture. The isochromatic fringe patterns obtained were analyzed using orthotropic photoelasticity to determine Mode-I stress intensity factors. Opening mode stress field equations in conjunction with an orthotropic stress-optic law were utilized to regenerate the isochromatic fringe patterns. Good agreement was found between the regenerated fringe patterns and the experimentally obtained patterns
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Bai, Shuang, and Jian Liu. "Femtosecond Laser Additive Manufacturing of Multi-Material Layered Structures." Applied Sciences 10, no. 3 (February 3, 2020): 979. http://dx.doi.org/10.3390/app10030979.
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Laser additive manufacturing (LAM) of a multi-material multi-layer structure was investigated using femtosecond fiber lasers. A thin layer of yttria-stabilized zirconia (YSZ) and a Ni–YSZ layer were additively manufactured to form the electrolyte and anode support of a solid oxide fuel cell (SOFC). A lanthanum strontium manganite (LSM) layer was then added to form a basic three layer cell. This single step process eliminates the need for binders and post treatment. Parameters including laser power, scan speed, scan pattern, and hatching space were systematically evaluated to obtain optimal density and porosity. This is the first report to build a complete and functional fuel cell by using the LAM approach.
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Seong, D. G., K. Chung, T. J. Kang, and J. R. Youn. "A Study on Resin Flow through a Multi-layered Preform in Resin Transfer Molding." Polymers and Polymer Composites 10, no. 7 (October 2002): 493–510. http://dx.doi.org/10.1177/096739110201000702.
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In resin transfer molding, mold filling is governed by the flow of resin through a preform which is considered as an anisotropic porous media. The resin flow is usually described by Darcy's law and the permeability tensor must be obtained for filling analysis. When the preform is composed of more than two layers with different in-plane permeability, effective average permeability should be determined for the flow analysis in the mold. The most frequently used averaging scheme is the weighted averaging scheme, but it does not account for the transverse flow between adjacent layers. A new averaging scheme is suggested to predict the effective average permeability of the multi-layered preform, which accounts for the transverse flow effect. When the flow in the mold is unsaturated, the effective average permeability is predicted by using the predicted mold filling time and transverse permeability. The new scheme is verified by measuring the effective permeability of the multi-layered preforms which consist of glass fiber random mats, carbon fiber woven fabrics, aramid fiber woven fabrics. Fluid flow through the preform composed of more than two layers with different in-plane permeability shows different flow fronts between layers. The difference in the flow front advancement is observed with a digital camcorder. The predicted flow front is compared with the experimental results and shows a good agreement. It is expected that the effective average permeability can be used for modeling the resin flow through the multi-layered preform.
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Juhlin, Erik, X. Chen, and T. D. Papathanasiou. "On the Effects of Fiber Length and Spatial Distribution on the Stiffness of Short-Fiber Reinforced Composites." Polymers and Polymer Composites 10, no. 3 (March 2002): 205–10. http://dx.doi.org/10.1177/096739110201000302.
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We report on the results of a computational investigation of the effect of fiber aspect ratio (ar) on the stiffness of composite rods reinforced with rigid spheroidal inclusions. The reinforcing spheroids are randomly placed within the containing rod and are also perfectly aligned with the tensile axis. Attention is focused in the interesting region of low (ar), where the stiffness of the composite rod is known to be most sensitive on (ar). Use of low aspect ratio fibers makes the results of this analysis suitable for a class of processed materials, such as whisker-reinforced metal-matrix composites and extruded or molded short-fiber-reinforced polymers. We consider steady-state three-dimensional deformations of composite rods containing up to 50 individual, randomly placed aligned spheroids. The equations of elasticity for the entire multi-fiber assembly are solved using the Boundary Element Method (BEM), implemented on a four-processor server and the force needed to impose a certain tensile deformation on the composite is computed. From this, an effective tensile modulus is obtained. Statistical averages of the computed effective moduli are compared to the predictions of the Mori-Tanaka model for the stiffness of short fiber composites. We find a good agreement at low values of (ar). Additionally, we investigate the effect on stiffness of random perturbations in fiber length around a mean value.
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Kuang, Jao Hwa, Tsung Pin Hung, Shian Huan Chiou, and Chao Ming Hsu. "Enhancement of Coupling Efficiency of Butterfly Package Laser Modules Based on Post-Weld-Shift Compensation." Applied Mechanics and Materials 145 (December 2011): 109–13. http://dx.doi.org/10.4028/www.scientific.net/amm.145.109.
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When fabricating laser diode transceiver modules, the coupling efficiency can be improved via a laser hammering process, in which additional, calculated spot welds are performed at key locations within the package in order to compensate for post-weld shift. The present study performs a numerical investigation into the post-weld-shift compensation of a butterfly laser module package incorporating a lensed optical fiber and a laser diode with a central wavelength of 980 nm. In performing the simulations, the deformation of the package components during the welding process is modeled using Marc finite element software. Furthermore, the laser power coupling efficiency is estimated using the commercial Zemax optical design program. It is shown that the numerical predictions for the coupling power in the laser diode transceiver module are in good agreement with the experimental results. The optimal welding sequence which minimizes the post-weld shift of the optical fiber relative to the laser diode is determined. It is shown that the corresponding coupling efficiency is equal to 69%. Finally, it is shown that by performing an optimized laser hammering process, the coupling efficiency can be improved to around 99%.
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Hu, Xueyan, Shengheng Zheng, Xingyuan Song, Xiaoxia Huang, Huaiwen Guo, Bowang Zhao, and Wei Zhou. "Research of Scattering Properties in Solid-Core Polarization-Maintaining Photonic Crystal Fibers." Optics 2, no. 2 (March 26, 2021): 63–69. http://dx.doi.org/10.3390/opt2020007.
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The scattering from air–glass interfaces within solid-core polarization-maintaining photonic crystal fiber (PM–PCF) will increase the fiber attenuation coefficient, which may lead to high transmission loss. Therefore, it is necessary to describe scattering properties to guide research into reducing fiber loss. In this paper, the loss resulting from roughness scattering at multi-hole interfaces within PM–PCF was theoretically and experimentally analyzed. A PM–PCF scattering model was established to explore the scattering distribution. On the other hand, a fully automatic testing device was built to enable the measurement of a three-dimensional scattering sphere. Simulations were in good agreement with experimental measurements. Moreover, this new proposed measurement method could apply to other PCFs and it will be a useful tool for further scattering research.
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Chun, Heoung Jae, H. W. Kim, and Joon Hyung Byun. "Elastic Behaviors of Stitched Multi-Axial Warp Knit Fabric Composites." Key Engineering Materials 306-308 (March 2006): 817–22. http://dx.doi.org/10.4028/www.scientific.net/kem.306-308.817.
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The purposes of stitching multi-axial warp knitted fabric preform prior to the fabrication of the composite materials by resin-transfer molding technique are to improve the resistance to delamination and to increase the out-of-plane properties of the composite materials for structural integrity. The influence of the through-the-thickness stitching on the elastic properties and behaviors of the multi-axial warp knit fabric composites is studied. An analytical model based on the representative volume is proposed to predict the elastic properties of the stitched multi-axial warp knit fabric composite materials. The fiber volume ratios determined by geometric parameters set by the representative volume and elastic behaviors of the in-situ constituent materials are used for the predictions. The crucial step in the analysis is to correlate the averaged stress states in the constituents by adopting bridging matrix. The predicted results are compared with the experimental results. It is found that the predicted results are in reasonably good agreement with the experimental results.
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Barnum, Carrie E., Salma Al Saai, Shaili D. Patel, Catherine Cheng, Deepti Anand, Xiaolu Xu, Soma Dash, et al. "The Tudor-domain protein TDRD7, mutated in congenital cataract, controls the heat shock protein HSPB1 (HSP27) and lens fiber cell morphology." Human Molecular Genetics 29, no. 12 (May 18, 2020): 2076–97. http://dx.doi.org/10.1093/hmg/ddaa096.
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Abstract Mutations of the RNA granule component TDRD7 (OMIM: 611258) cause pediatric cataract. We applied an integrated approach to uncover the molecular pathology of cataract in Tdrd7−/− mice. Early postnatal Tdrd7−/− animals precipitously develop cataract suggesting a global-level breakdown/misregulation of key cellular processes. High-throughput RNA sequencing integrated with iSyTE-bioinformatics analysis identified the molecular chaperone and cytoskeletal modulator, HSPB1, among high-priority downregulated candidates in Tdrd7−/− lens. A protein fluorescence two-dimensional difference in-gel electrophoresis (2D-DIGE)-coupled mass spectrometry screen also identified HSPB1 downregulation, offering independent support for its importance to Tdrd7−/− cataractogenesis. Lens fiber cells normally undergo nuclear degradation for transparency, posing a challenge: how is their cell morphology, also critical for transparency, controlled post-nuclear degradation? HSPB1 functions in cytoskeletal maintenance, and its reduction in Tdrd7−/− lens precedes cataract, suggesting cytoskeletal defects may contribute to Tdrd7−/− cataract. In agreement, scanning electron microscopy (SEM) revealed abnormal fiber cell morphology in Tdrd7−/− lenses. Further, abnormal phalloidin and wheat germ agglutinin (WGA) staining of Tdrd7−/− fiber cells, particularly those exhibiting nuclear degradation, reveals distinct regulatory mechanisms control F-actin cytoskeletal and/or membrane maintenance in post-organelle degradation maturation stage fiber cells. Indeed, RNA immunoprecipitation identified Hspb1 mRNA in wild-type lens lysate TDRD7-pulldowns, and single-molecule RNA imaging showed co-localization of TDRD7 protein with cytoplasmic Hspb1 mRNA in differentiating fiber cells, suggesting that TDRD7–ribonucleoprotein complexes may be involved in optimal buildup of key factors. Finally, Hspb1 knockdown in Xenopus causes eye/lens defects. Together, these data uncover TDRD7’s novel upstream role in elevation of stress-responsive chaperones for cytoskeletal maintenance in post-nuclear degradation lens fiber cells, perturbation of which causes early-onset cataracts.
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Graiff, Lorenzo, Laura Rasera, Marco Calabrese, and Paolo Vigolo. "Bonding Effectiveness of Two Adhesive Luting Cements to Glass Fiber Posts: Pull-Out Evaluation of Three Different Post Surface Conditioning Methods." International Journal of Dentistry 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/148571.
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The purpose of this study was to evaluate the bond strength at the post/resin-cement interface with 3 different surface treatments of glass fiber posts and with 2 different luting resin cements. Sixty glass fiber posts (RelyX Fiber Post) were randomly divided into 3 groups (n=20) and were luted with a dual-polymerizing self-adhesive universal resin cement (RelyX Unicem) and with a dual-polymerizing resin cement (RelyX ARC). This was carried out in association with a dual-polymerizing adhesive (Scotchbond Multi-Purpose Plus) in simulated plexiglass root canals after receiving three different pretreatment procedures. A pull-out test was performed on each sample to measure bond strengths. Data were analyzed with two-way ANOVA. Two samples from each group were processed for SEM observations in order to investigate the morphologic aspect of the post/cement interface. Both resin cements demonstrated significant different bond strength values (P<0.0001). The surface treatment result was also statistically significant (P=0.0465). SEM examination showed a modification of the post surface after pretreatment with methyl methacrylate. The dual-polymerizing self-adhesive universal resin cement achieved higher MPa bond strength values. The use of methyl methacrylate as a surface treatment of glass fiber posts provided a significant increase in bond strengths between the posts and both luting materials.
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Izamshah, Raja, Zainudin Zuraidah, Mohd Shahir Kasim, M. Hadzley, and M. Amran. "Multi Objective Optimization of Cutting Parameters in Machining Cellulose Based Hybrid Composites." Applied Mechanics and Materials 761 (May 2015): 287–92. http://dx.doi.org/10.4028/www.scientific.net/amm.761.287.
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Cellulose based hybrid composites are gaining popularity in the growing green communities. With extensive studies and increasing applications for future advancement, the need for an accurate and reliable guidance in machining this type of composites has increased enormously. Smooth and defect free machined surface are always the ultimate objectives. The present work deals with the study of machining parameters (i.e. spindle speed, feed rate and depth of cut) and their effects on machining performance (i.e. surface roughness and delamination) to establish an optimized setup of machining parameters in achieving multi objective machining performance. Cellulose based hybrid composites consist of jute (a bast fiber) and glass fiber embedded in polyester resins. Response Surface Methodology (RSM) using Box-Behnken Design (BBD) was chosen as the design of experiment approach for this study. Based on that experimental approach, 17 experimental runs were conducted. Mathematical model for each response was developed based on the experimental data. Adequacy of the models were analyzed statistically using Analysis of Variance (ANOVA) in determining the significant input variables and possible interactions. The multi objective optimization was performed through numerical optimization, and the predicted results were validated. The agreement between the experimental and selected solution was found to be strong, between 95% to 96%, thus validating the solution as the optimal machining condition. The findings suggest that feed rate was the main factor affecting surface roughness and delamination .
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Kumari, Punita, Jihui Wang, and Saahil Khan. "Residual Tensile Strength of the Multi-Impacted Scarf-Repaired Glass Fiber-Reinforced Polymer (GFRP) Composites." Materials 11, no. 12 (November 22, 2018): 2351. http://dx.doi.org/10.3390/ma11122351.
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The effect of multiple/repeated impacts on a repaired composite was investigated using a low-velocity impact test. The composite samples were fabricated through a vacuum resin infusion method (VARI) and repaired by a scarf repair technique. Later, a repeated low-velocity impact test was performed on the original and repaired composites samples. Performance of the multi-impacted repaired and original samples was evaluated and compared by measuring maximum contact force, maximum displacement, maximum time duration, absorbed energy and damage area. Photographs of the post-impacted samples were taken to observe the multi-impact damage progression through visual inspection. The results showed that each repeated impact subjected the samples to more damage. Tensile tests revealed that the scarf repair restored 81.23% strength. It was also observed that the sample obtained the highest damage dent in the low-velocity impact test that failed early during a tensile test and carried the lowest ultimate load.
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Inglev, Rune, Jakob Janting, and Ole Bang. "Annular Cavity Design for Photoluminescent Polymer Optical Fiber Sensors." Sensors 20, no. 18 (September 11, 2020): 5199. http://dx.doi.org/10.3390/s20185199.
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We present optimization results on the design of a polymer optical fiber single point sensor suitable for photoluminescence-based sensing. The single point sensing design consists of one or two annular cavities, separated by a small distance, milled into the fiber and subsequently filled with a thick solution of polymer, solvent, and photoluminescent molecules, which is then allowed to dry. The design is tested by varying the depth and length of a single cavity and utilizing two cavities with varying separations. Results from experiments show a maximum response at a separation of 2 mm for which we present an analytical explanation. A geometrical, numerical simulation model, taking into account both skew and meridional rays, is developed and shows very good agreement with the experimental results. The fiber design presents a general platform that has the potential for the fabrication of multi-point photoluminescent sensors, for which it is necessary to have several points along the fiber functionalized for sensing. Furthermore, the approach with polymer fibers and polymer sensing gels allows for a robust integration of the sensing matrix and the optical fiber, more so than is possible using glass optical fibers.
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Richert, Raphaël, Philip Robinson, Gilbert Viguie, Jean-Christophe Farges, and Maxime Ducret. "Multi-Fiber-Reinforced Composites for the Coronoradicular Reconstruction of Premolar Teeth: A Finite Element Analysis." BioMed Research International 2018 (June 7, 2018): 1–6. http://dx.doi.org/10.1155/2018/4302607.
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A coronoradicular reconstruction (CRR) has conventionally used a metallic inlay core (MIC) or a single-fiber-reinforced composite (sFRC) but extensive dentin removal can lead to root fracture. We propose herein a multi-fiber-reinforced composite (mFRC) based on a bundle of thin flexible fibers that can be adapted to the root anatomy without removing additional dentin. The aim of this study was to compare the mechanical behavior of the root reconstructed with mFRC, MIC, or sFRC using a finite element analysis (FEA). Models with or without a ferrule effect were created using Autodesk© software and divided into four parts: root, post, bonding composite or cement, and zirconia crown. For both models, extreme stress values (ESV), stress distribution, and risk of fracture were calculated for an oblique force (45°) of 100 N applied to the top of the buccal cusp. Results indicated that mFRC and mFRCG present a lower risk of fracture of the root and of the CRR without ferrule and thus could be valuable alternatives for premolar CRR. Further studies are necessary to evaluate the clinical success of these CRR.
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Nam, Ahhyun, Jian Ren, Brett Bouma, and Benjamin Vakoc. "Demonstration of Triband Multi-Focal Imaging with Optical Coherence Tomography." Applied Sciences 8, no. 12 (November 26, 2018): 2395. http://dx.doi.org/10.3390/app8122395.
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We demonstrate an extended depth of focus optical coherence tomography (OCT) system based on the use of chromatic aberration to create displaced focal planes in the sample. The system uses a wavelength-swept source tuning over three spectral bands and three separate interferometers, each of which interfaces to a single illumination/collection fiber. The resulting three imaged volumes are merged in post-processing to generate an image with a larger depth of focus than is obtained from each band individually. The improvements are demonstrated in structural imaging of a porous phantom and a lipid-cleared murine brain, and by angiographic imaging of human skin. By using a coaxial approach with Gaussian beams, this approach enables an extended focus with relatively simple microscope optics and data-merging algorithms.
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K. Khairi, K. Khairi, H. Fong Kok H. Fong Kok, Z. Lambak Z. Lambak, M. I. Abdan M. I. Abdan, M. A. Farhan M. A. Farhan, M. H. Othman M. H. Othman, M. L. H. Jamaluddin M. L. H. Jamaluddin, et al. "Investigation on the pre-compensation and post-?compensation cascaded multi-channel-chirped fiber Bragg gratings for a repeaterless transmission system." Chinese Optics Letters 16, no. 4 (2018): 040607. http://dx.doi.org/10.3788/col201816.040607.
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Jee, Min Ho, and Doo Hyun Baik. "Morphological and Electrical Properties of Multi-Walled Carbon Nanotube-based Fiber Using General Wet-spinning and Alkaline Post-treatment Methods." Fibers and Polymers 21, no. 11 (November 2020): 2456–61. http://dx.doi.org/10.1007/s12221-020-0942-1.
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Zhou, Rui, Weicheng Gao, and Wei Liu. "An MMF3 Criterion Based Multi-Scale Strategy for the Failure Analysis of Plain-Woven Fabric Composites and Its Validation in the Open-Hole Compression Tests." Materials 14, no. 16 (August 5, 2021): 4393. http://dx.doi.org/10.3390/ma14164393.
Full textAbstract:
A modified micromechanics failure criterion (MMF3) based multi-scale analysis strategy was proposed in this article to analyze the failure behaviors of the plain-woven fabric composites. The finite-element (FE) representative unit cell (RUC) models of different scales were first established, and the RUC based stress transformation methods were developed. The micro-scale strengths of the constituents in the unidirectional laminate were achieved based on the tested macro-scale strengths. Under the micro-scale strength invariance hypothesis, the meso-scale strengths of the fiber tows from the plain-woven fabric composites were back-calculated first and were then validated and corrected with the assistance of tested strengths of the fabric laminates. With the micro-scale RUC and the calculated meso-scale strengths of the fiber tows, the micro-scale strengths of the constituents suitable for the plain-woven fabric composites were determined. The multi-scale analysis procedure for the plain-woven fabric composites was then established in providing a more direct failure observation at the constituent level. Open-hole compression specimens were tested according to the ASTM standard D6484, and the failure of the open-hole fabric laminate was simulated with the proposed multi-scale strategy. The numerical predictions were in good agreement with the experimental results, and the feasibility of the multi-scale strategy was validated.