• International Journal of Industrial Entomology and Biomaterials
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• v.44 no.1
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• pp.12-20
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• 2022

In this research, the silk web was hot-pressed for various times, the effect of press time on the structure and mechanical properties of silk non-woven fabric was also investigated. The yellowing appeared in the silk non-woven fabric and became more apparent as press time was increased. The crystallinity of silk was decreased by the hot press treatment and it did not change significantly with an increase of hot press time. The porosity of silk non-woven fabric was constantly decreased until 120 s and it did not change much after that. The thickness of silk non-woven fabric was significantly decreased by a press time of 10 s and slightly decreased with a further increase of hot press time. The hot press treatment increased the maximum stress and elongation of silk non-woven fabrics. The press time had a significant impact on the mechanical properties of silk non-woven fabric, with 90 s being the optimum condition for the best work of rupture of silk non-woven fabric.

• Steel and Composite Structures
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• v.26 no.3
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• pp.289-301
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• 2018

The rigid steel connections were suffered severe damage because of low rotational capacity during earthquakes. Hence, many investigations have been conducted on the connections of steel structures. As a solution, steel slit dampers were employed at the connections to prevent brittle failure of connections and damage of main structural members. Slit damper is a plate or a standard section with a number of slits in the web. The objective of this paper is to improve the seismic performance of steel slit dampers in the beam-to-column connection using finite element modeling. With reviewing the previous investigations, it is observed that slit dampers were commonly fractured in the end parts of the struts. This may be due to the low participation of struts middle parts in the energy dissipation. Thus, in the present study slit damper with elliptic slits is proposed in such a way that end parts of struts have more energy absorption area than struts middle parts. A parametric study is conducted to investigate the effects of geometric parameters of elliptic slit damper such as strut width, strut height and plate thickness on the seismic performance of the beam-to-column connection. The stress distribution is improved along the struts in the proposed slit damper with elliptic slits and the stress concentration is decreased in the end parts of struts. The average contributions of elliptic slit dampers, beam and other sections to the energy dissipation are about 97.19%, 2.12% and 0.69%, respectively.

• Steel and Composite Structures
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• v.3 no.4
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• pp.261-275
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• 2003

Truss members built-up with double angles back-to-back have monosymmetric cross-section and twisting always accompanies flexion upon the onset of buckling about the axis of symmetry. Approximate formulae for calculating the buckling capacity are presented in this paper for routine design purpose. For a member susceptible only to flexural buckling, its optimal cross-section should consist of slender plate elements so as to get larger radius of gyration. But, occurrence of twisting changes the situation owing to the weakness of thin plates in resisting torsion. Criteria for limiting the leg slenderness are discussed herein. Truss web members in compression are usually considered as hinged at both ends for out-of-plane buckling. In case one (or both) end of member is not supported laterally by bracing member, its adjoining members have to provide an elastic support of adequate stiffness in order not to underdesign the member. The stiffness provided by either compression or tension chords in different cases is analyzed, and the effect of initial crookedness of compression chord is taken into account. Formulae are presented to compute the required stiffness of chord member and to determine the effective length factor for inadequately constrained compressive diagonals.

• The Journal of Korean Physical Therapy
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• v.33 no.6
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• pp.297-303
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• 2021

Purpose: The mass of facial muscles can be increased through exercise, as is also the case for muscles in the extremities. This systematic review was conducted to investigate the effect of facial exercises on facial muscle strengthening and facial rejuvenation, focusing on recent studies. Methods: A literature search was performed using the PubMed, ScienceDirect, and Web of Science databases. The quality of the trials was evaluated according to the PEDro scale. In total, 11 studies were included in this review: four studies on facial exercise for facial rejuvenation and seven studies on strengthening the muscles of the face. Results: Facial exercises for facial rejuvenation increased the mechanical properties and elasticity of the skin of the face and neck, the thickness and cross-sectional area of the facial muscles, and the fullness of the upper and lower cheeks. Conclusion: A study aimed at strengthening facial muscles showed improvements in labial closure strength and tongue elevation strength. Despite the positive results for facial rejuvenation and muscle strengthening, the level of evidence was low. Therefore, in future research, it will be necessary to investigate the effects of facial exercise in a thoroughly controlled experiment with a sufficient sample size to increase the level of evidence.

• Structural Engineering and Mechanics
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• v.86 no.3
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• pp.417-430
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• 2023

As the key part in the reinforced concrete column-steel beam (RCS) frame, the beam-column joints are usually subjected the axial force, shear force and bending moment under seismic actions. With the aim to study the seismic behavior of RCS joints with and without RC slab, the quasi-static cyclic tests results, including hysteretic curves, slab crack development, failure mode, strain distributions, etc. were discussed in detail. It is shown that the composite action between steel beam and RC slab can significantly enhance the initial stiffness and loading capacity, but lead to a changing of the failure mode from beam flexural failure to the joint shear failure. Based on the analysis of shear failure mechanism, the calculation formula accounting for the influence of RC slab was proposed to estimate shear strength of RCS joint. In addition, the finite element model (FEM) was developed by ABAQUS and a series of parametric analysis model with RC slab was conducted to investigate the influence of the face plates thickness, slab reinforcement diameter, beam web strength and inner concrete strength on the shear strength of joints. Finally, the proposed formula in this paper is verified by the experiment and FEM parametric analysis results.

• Animal cells and systems
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• v.7 no.1
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• pp.43-47
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• 2003

The skin of the eel goby, Odontamblyopus lacepedii, consists of epidermis, dermis and subcutis. The epidermis has three layers: the outermost layer, middle layer and stratum germinativum. The outermost layer is composed of polygonal cells or rather flattened cells, and mucous gland cells of acid mucopolysaccharides. The middle layer consists mainly of swollen small or voluminous epidermal cells and shows a web-shaped structure. The thickness of the epidermis depends on the various sizes and the number of layers of the swollen cells. Well-developed lymphatic spaces containing lymphocytes exist in the stratum germinativum and small scales are embedded in the dermis. A large number of blood capillaries are present just below the basement membrane, and a definite area giving AB and PAS positive was present between the basement membrane and scales, Taste buds ave distributed on surface of the epidermis at intervals. Considering the structural features of the skin, it may be considered that O. lacepedii is more likely to be related to cutaneous respiration as a dual respiratory system.

• Steel and Composite Structures
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• v.51 no.3
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• pp.225-241
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• 2024

For several reasons, cold-formed steel (CFS) beams are often manufactured with holes. Nevertheless, because of holes, the reduction in the web area causes a decrease in the bending strength. Edge stiffeners are presently added around the holes to improve the bending strength of flexural members. Therefore, this research studies CFSZ-beams with stiffened holes and investigates how edge stiffener affects bending strength and failure modes. Nonlinear analysis was carried out using ABAQUS software and the developed finite element (FE) model was verified against tests from previous studies. Using the verified FE model, a parametric study of 104 FE models was conducted to investigate the influence of key parameters on bending strength of Z- sections. The results indicated that the effect of holes is less noticeable in very thin Z-sections. Moreover, adding edge stiffeners around the holes improves the flexural capacity of Z-beams and sometimes restores the original bending capacity. Because the computational techniques used to solve the CFS buckling mode with stiffened holes are still unclear, a numerical method using constrained and unconstrained finite strip method (CUFSM) software was proposed to predict the elastic distortional buckling moment for a wide variety of CFSZ-sections with stiffened holes. A numerical method with two procedures was applied and validated. Upon comparison, the numerical method accurately predicted the distortional buckling moment of CFS Z-sections with stiffened holes.

• Textile Coloration and Finishing
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• v.27 no.4
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• pp.327-333
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• 2015

This paper aims to manufacture nonwoven fabrics by wet-laid technology using Vectran$^{(R)}$ one of the highly favoured high-performace fiber. In previous study, a novel evaluation on fiber dispersion was studied to select optimum surfactant by the need for the control of fiber dispersion in water with reference to wet-laid nonwoven technology. 3 Types of sulfonate anionic surfactants were chosen and added in a stage of agitation to improve dispersion behavior of fibers in water. It was observed that the state of fiber dispersion in water affected various properties of nonwovens, including appearance, physical properties, and mechanical properties. Nonwoven added SDBS was uniform in web structure, thickness and weight. Its average pore was small in size and consisted of fine pores and the value of porosity was high. Further, the difference of tensile value between 2 directions was the least. Consequentially, as the dispersion behavior of fiber increases, nonwoven shows more balanced and uniform physical properties in all directions.

• Steel and Composite Structures
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• v.2 no.3
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• pp.171-194
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• 2002

In this paper, the behaviour of axially loaded partially encased composite columns made with light welded H steel shapes is examined using ABAQUS finite element modelling. The results of the numerical simulations are compared to the response observed in previous experimental studies on that column system. The steel shape of the specimens has transverse links attached to the flanges to improve its local buckling capacity and concrete is poured between the flanges only. The test specimens included 14 stubcolumns with a square cross section ranging from 300 mm to 600 mm in depth. The transverse link spacing varied from 0.5 to 1 times the depth and the width-to-thickness ratio of the flanges ranged from 23 to 35. The numerical model accounted for nonlinear stress-strain behaviour of materials, residual stresses in the steel shape, initial local imperfections of the flanges, and allowed for large rotations in the solution. A Riks displacement controlled strategy was used to carry out the analysis. Plastic analyses on the composite models reproduced accurately the capacity of the specimens, the failure mode, the axial strain at peak load, the transverse stresses in the web, and the axial stresses in the transverse links. The influence of applying a typical construction loading sequence could also be reproduced numerically. A design equation is proposed to determine the axial capacity of this type of column.

• Computers and Concrete
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• v.13 no.2
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• pp.209-220
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• 2014

Vibration based damage detection is very popular in the civil engineering area. Especially, special structures like dams, long-span bridges and high-rise buildings, need continues monitoring in terms of mechanical properties of material, static and dynamic behavior. It has been stated in the International Commission on Large Dams that more than half of the large concrete dams were constructed more than 50 years ago and the old dams have subjected to repeating loads such as earthquake, overflow, blast, etc.,. So, some unexpected failures may occur and catastrophic damages may be taken place because of theloss of strength, stiffness and other physical properties of concrete. Therefore, these dams need repairs provided with global damage evaluation in order to preserve structural integrity. The paper aims to show the effectiveness of the model updating method for global damage detection on a laboratory arch dam model. Ambient vibration test is used in order to determine the experimental dynamic characteristics. The initial finite element model is updated according to the experimentally determined natural frequencies and mode shapes. The web thickness is selected as updating parameter in the damage evaluation. It is observed from the study that the damage case is revealed with high accuracy and a good match is attained between the estimated and the real damage cases by model updating method.