Flat Strip Research Articles

LNG선 화물격납용기 Invar strake edge 이음부 형상 개선에 관한 연구

The membrane of the LNG carriers consists of thin strips of INVAR(Fe-36%Ni) steel plates, and the junction between INVAR strips is fabricated by welding. Thousands of the raised edge joints, regularly spaced, are located around all the side of the tank corner near the transverse bulkhead, and TIG welding is manually made on the top of the raised edges. Since the thickness of all the laminated edge plies is extremely thin and the weld position is under a bad accessibility, highly skilled workers are required to perform welding relatively for a long welding time. An alternative scheme for the corner membrane fabrication is proposed in the study to improve the installation workability and thus productivity. The scheme replaces the welded edges with the preformed corrugation ones. A panel strip with regularly-spaced corrugations is installed at the corner instead of the individual flat strip of which edge is vertically raised to be welded with the adjacent strip. In the study, a series of the evaluation on the corrugated edge members was performed to assess the applicability to the real LNG carrier fabrication. Opening displacement at the raised edge was experimentally examined. Elastic stiffness regressed from the displacement was nearly same in both edge types. Edge displacement and local stresses were calculated under hydrostatic pressure and temperature change due to liquefied cargo. Fatigue test was performed on both corrugated and welded edge specimens consisting of two or five plies of invar strips. Fatigue strength of the corrugated specimens was not less than that of the welded specimens.

Development of tribo-simulator for hot stamping

Coefficients of friction were measured at elevated temperatures using a hot flat strip drawing test machine newly developed by the authors for the purpose of confirming the coefficients of friction used for the FEM simulation of hot stamping. To examine the functions of the tribo-simulator, the coefficients of friction are measured using hot rolling oil with an emulsion, which is supplied continuously, while varying the drawing speed, drawing pressure and temperature. From the experimental results, it was shown that the coefficient of friction in hot stamping can be measured using this tribo-simulator. The measured coefficients of friction can be used as values in the FEM simulation of hot stamping. Moreover, the tribological behavior at the interface between the die and strip in hot stamping can be evaluated from the coefficient of friction, because it is one of the quantitative values used to represent the tribological behavior between the die and blank.

Möbius strips with flat metrics

This paper is focused on flat Mobius strips. The first section presents some results related to asymptotic parameterization of such surfaces. The second section contains studies of their bendability. It is proved that any Mobius strip isometric to a surface obtained by suitably glueing a flat rectangle admits a non-trivial bending which is a slide along itself. A concrete numerical computation of such bending is given.

Characterization of Switchable Substrateless Frequency Selective Surfaces

In this paper, a new means for characterization of switchable substrateless frequency selective surfaces (FSS) was demonstrated with numerical and experimental approaches. The diodes model loaded active doubly periodic flat strip FSS acts as a dynamic screen, in which its surface reflectivity and transmittivity can be switched alternately and tuned through d.c. bias voltage control. The properties of FSS layer are characterized using a specially designed parallel plate waveguide (PPW) simulator that permits normal incidence excitation of the FSS under test and the responses are found between 3 to 5 GHz. It is shown that by means of d.c. bias control, the screen can be utilized in, (a) transmission mode as a dual band electromagnetic shutter, or, (b) reflection mode, as an amplitude shift keying (ASK) spatial modulator or dual band reflection canceller. In addition a hybrid de-embedding technique is employed to remove the influence the PPW simulator and reveal the true property of substrateless FSS. Typical experimental results are presented and validated against a new 3D electromagnetic (EM) modeling led de-embedding method for the composite FSS layer and PPW structure.

Development of strips of ovine testes after xenografting under the skin of mice and co-transplantation of exogenous spermatogonia with grafts

Xenografting of testicular tissue is an attractive new strategy for studying postnatal development of spermatogenesis and to preserve male genetics in large mammals. Typically, small cubes of immature testis (1 mm(3)) are grafted under the dorsal skin of immune-deficient mice. We attempted to increase the total number of seminiferous tubules in each xenograft with spermatogenesis by grafting flat strips of testis (approximately 9 x 5 x 1 mm) from ram lambs in immune-deficient mice. The percentage of grafts that survived and percentage of seminiferous tubules that developed spermatogenesis were the same as those reported after xenografting small cubes of lamb testis. Partially purified sheep spermatogonia were labeled with the fluorescent dye carboxy fluorescein diacetate succinyl diester and transplanted into the seminiferous tubules of one of the donor testis just before engraftment. The temporary label in the donor cells was detected for 4 weeks after xenografting, suggesting that co-engraftment of spermatogonia with testicular tissue may be a way to rapidly determine the effect of a specific gene on spermatogenesis. Finally, Sertoli cell lesions in xenografts of lamb testes were quantified, and their number and severity were found to increase, especially after grafts had been in place for 4 weeks. Although this coincided with the development of spermatogenesis, the extent of germ cell differentiation negatively correlated with severity of the lesions.

Frequency selective surface with dual band switchable reflection and transmission characteristics

AbstractA pin diode‐loaded active doubly periodic flat strip FSS is shown to act as a dynamic screen. It is shown that by means of d.c. bias control, we can utilize the screen in, (1) transmission mode as a dual band electromagnetic shutter, or with the inclusion of a ground plane in reflection mode, as (2) a dual band refection canceller, (3) an amplitude shift keying (ASK) spatial modulator. The properties of the FSS are characterized using a specially designed parallel plate waveguide simulator that permits normal incidence excitation of the FSS under test. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2059–2061, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24547

Caracterização físico-mecânica do laminado colado de bambu (<i>Dendrocalamus giganteus</i>).

Esta pesquisa teve como objetivo avaliar a influência do tratamento preservativo e do tipo de adesivo nas propriedades físico-mecânicas do laminado colado, confeccionado com o bambu Dendrocalamus giganteus. Para tanto, colmos de bambu foram tratados pelo método de imersão em produto químico (solução de 1% de ingredientes ativos de borato de cobre cromatado - CCB) e em água, durante 15 dias. Dos colmos tratados, foram retiradas as camadas externa e interna, obtendo-se lâminas com espessuras de 4 mm, comprimento de 45 cm e largura de 5 cm. Para a colagem das lâminas, utilizaram-se os adesivos "Cascophen RS" (resorcinol-formol) e "Cascorez-Extra" (acetato polivinílico). O adesivo à base de resorcinol-formol proporcionou maior resistência à umidade ao BLC, quando comparado àquele à base de acetato polivinílico, tendo as amostras provenientes de peças tratadas com CCB sido mais estáveis que as tratadas com água. Dentre as propriedades mecânicas testadas, o adesivo apresentou resultado significativo para o cisalhamento na linha de cola e o tratamento preservativo para o MOE. A interação dos fatores adesivo e tratamento foi significativa para o MOE, resistência a compressão paralela ao cisalhamento na linha de cola, tendo as peças tratadas com água e aderidas com resorcinol-formol apresentado melhores resultados para o MOE e compressão paralela às fibras e aquelas tratadas com CCB, para o cisalhamento na linha de cola.

3D FINITE ELEMENT MODELLING OF COMPLEX STRIP ROLLING

A main feature of complex strip - ribbed strip is the significant local residual deformation on a flat strip, resulting in the pulling down of rib height. The interesting issue in this paper shows a developed three-dimensional finite element model of the complex strip rolling, coupling the use of an extremely thin array of elements which is equivalent to the calculation of the additional shear deformation work rate occurred by the velocity discontinuity in the deformation zone. The 3D finite element modelling includes the consideration of the special rib inclined contact surface boundary condition has been carried out on a computer. An examination of the equivalent stress field, forward slip and rib height demonstrates the effectiveness of the developed model. The computed forward slip and rib height are in good agreement with the measured values. The effect of the rib inclined angle on the pulling down of rib height is also discussed.

Texture and mechanical anisotropy in three extruded magnesium alloys

One ZM61 alloy (6·2%Zn, 1·2%Mn) and two magnesium alloys containing nominally 3% of neodymium and yttrium respectively have been prepared in the form of hot extruded flat strips. Their textures and microstructures have been quantified and series of mechanical tests were carried out to determine plane stress yield loci in both the solution treated and aged conditions. The ZM61 alloy had a sharp texture and marked anisotropy of strength that could be rationalised in terms of deformation by basal <a> slip and {1012}<1011> twinning. This material was much weaker in compression than in tension. Precipitation hardening on aging caused a greater impedance to twinning than to slip with the result that the anisotropy was somewhat reduced. The Mg–3Nd alloy had a very weak and different texture but nevertheless demonstrated a pronounced anisotropy of strength. Aging increased the yield stress by about 80% and also inhibited twinning to some extent although the degree of anisotropy remained almost unaffected. The Mg–3Y alloy which showed a texture of intermediate strength was different in type from either of the others. Its strength behaviour was close to isotropic; in particular, no difference existed between tensile and compressive loading, and aging produced only a marginal increase in strength. Twins were relatively infrequent in the deformed Mg–3Y alloy but its mechanical behaviour could not be rationalised according to simple models.

Metallurgical characterization of refrigeration tubing formed from plain carbon steel strip stock

Ball indentation hardness testing and metallography were used to investigate the metallurgical changes that occur during the manufacture and bending of plain carbon steel tubing for use in large-scale refrigeration equipment such as evaporative condensers and thermal storage coils. A significant increase in hardness occurred in going from flat strip starting material to creating the electrical resistance welded tubing that was subsequently bent to form coils. The weld region exhibited the greatest hardness. Metallographic examination revealed that the spheroidized ferritic microstructure of the flat strip was retained during welding. However, the accompanying heating did cause small grains to form and a significant rise in the number of carbide particles.

TM and TE Diffraction by a Perfectly Conducting Half-Plane in Presence of a Perfectly Conducting Strip: Solution by Exponentially Converging Nystrom and Galerkin Methods

We study TM and TE diffraction by a perfectly conducting half-plane in presence of a perfectly conducting flat strip of finite width and infinite length; the edges of the strip are parallel to the edge of the half-plane. The relevant integral equations with unknowns the induced current densities on the strip are solved by a Nystrom and a Galerkin method that fully account for the singular nature of the kernels and the singularities of the solution at the edges. The proposed algorithms are highly accurate, and appear to converge exponentially as shown by detailed numerical examples and case studies. The Nystrom method is the most efficient of the two methods because of its simple formulation, fast computer implementation, and much less effort in computing the matrix elements. When the strip is coplanar to the half-plane, an additional formulation method in terms of equivalent surface magnetic currents is possible in the framework of the field equivalence principles. This alternative method is applied in order to validate the algorithms and test their accuracy.

The effect of proteolytic treatment on plastic deformation of porcine aortic tissue

The objective of this work was to assess whether selective proteolysis of elastin and/or collagen in a porcine aorta followed by mechanical creep loading would result in an aneurysm-like permanent tissue stretch. The underlying motivations were to (1) test the feasibility of developing an in vitro abdominal aortic aneurysm (AAA) model, and (2) understand what role, if any, that passive creep-induced stretching plays in aneurysmal dilation. Multiple circumferentially oriented flat specimen strips were cut from the porcine thoracic aorta of ten adult pigs. Specimens were subjected to one of six treatment protocols: Untreated controls ( U C ; N = 23 ) , complete elastin degradation ( E ; N = 10 ) , partial elastin degradation ( E p ; N = 10 ) , partial collagen degradation ( C p ; N = 22 ) , and partial degradation of both elastin and collagen ( E p + C p ; N = 3 ) . All specimens were then subjected to cyclic creep (10 min/cycle) with increasing load amplitude until failure. The zero-load strain prior to the creep cycle where failure occurred was defined as load-induced plastic strain. The plastic strain induced by treatment alone, creep loading alone and the total was determined for all specimens. The total plastic strain was significantly greater for E (mean ± SD = 48.2 ±17.6, p<0.005), E p ( 41.6 ± 11.1 , p < 0.0005 ) , but not for E p + C p ( 48.9 ± 21.6 , p = 0.17 ) and C p ( 22.2 ± 12.8 , p = 0.14 ) compared to UC (17.7±6.1). Of the total plastic strain, treatment-induced plastic strain was high for those specimens subjected to partial or total elastin degradation ( E , E p , E p + C p ) , but not for those where elastin was intact ( C p ) . However, load-induced plastic strain in the treated specimens was not different in any of the treated groups compared to controls. Maximum total plastic strain of 78.6% was induced in one porcine aortic tissue from the E group. Even this is far lower than what would be needed for creating a realistic in vitro AAA model. Our findings do not support the feasibility of developing an in vitro AAA by enzymolysis followed by passive stretching of the aorta. The findings also suggest that AAA formation is unlikely to be a passive creep-induced stretching of a proteolytically degraded aortic wall as conventional thinking may suggest, but rather may be predominantly due to growth and remodeling of the aortic wall.

Frequency-Independent Scattering From a Flat Strip With ${\rm TE}_{z}$-Polarized Fields

The surface current for scattering from a PEC strip naturally decomposes into three slowly varying functions modulating rapidly oscillating phase factors. We exploit this structure to derive a numerical solution that is error-controllable and exhibits a bounded error over the full range of frequencies. Frequency independence is obtained by expanding the current in terms of slowly-varying amplitude functions, stretching coordinates in the boundary layer, and employing a frequency-independent quadrature rule. Though the total current solution is always well-defined, unique, minimally-varying amplitude functions may also be found by using the minimum norm concept.

Influence of waveguide geometry on scattering loss effects in submicron strip silicon-on-insulator waveguides

Silicon-on-insulator (SOI) optical waveguides with high electromagnetic field confinement suffer from side-wall roughness, which is responsible for strong scattering inducing propagation loss. A theoretical investigation of the influence of geometry in submicron SOI waveguides on the scattering loss due to side-wall roughness is reported. Scattering loss coefficient is derived for both narrow and flat SOI strip waveguides. It is shown that scattering loss coefficient is significantly increased for narrow waveguides compared with flatter ones. These results show that attention has to be paid to waveguide geometry, as scattering effects are the predominant source of optical losses in strip submicron SOI optical waveguides.

Calculation of thermal stress affecting strip flatness change during run-out table cooling in hot steel strip rolling

To fulfill further reducing production costs at the meantime enhancing product quality is always one of the objectives pursued by steel enterprises and researches. With increasing demand on higher quality of hot rolled strip shape, strip flatness change developed during cooling on the run-out table has received significant attention and should be considered in online strip shape control model. Non-uniformity of transverse temperature distribution in strip is the ultimate reason for the occurring of strip flatness defect after hot rolled flat strip is cooled to room temperature. Based on the large amount of thermal image field measurements on strip surface, transverse temperature distribution rules of strip were concluded. A FE model was established to analyze the thermal stresses developed during the cooling of hot rolled strip on the run-out table using finite element program ABAQUS. Analysis results demonstrate that temperature drop within strip edge region will make strip flatness develop to the trend of edge wave and are verified by the actual strip flatness observation on skin pass rolling line. This viewpoint agrees well with the actual production condition. One compensation control strategy, named slight center wave rolling, is proposed based on the FE analysis work. The main idea is that steel strip is rolled with slight center wave at the exit of the last stand of finishing mill to compensate the flatness change trend of edge wave during the cooling.

Characteristics of surface sound pressure and absorption of a finite impedance strip for a grazing incident plane wave

Distributions of sound pressure and intensity on the surface of a flat impedance strip flush-mounted on a rigid baffle are studied for a grazing incident plane wave. The distributions are obtained by superimposing the unperturbed wave (the specularly reflected wave as if the strip is rigid plus the incident wave) with the radiated wave from the surface vibration of the strip excited by the unperturbed pressure. The radiated pressure interferes with the unperturbed pressure and distorts the propagating plane wave. When the plane wave propagates in the baffle-strip-baffle direction, it encounters discontinuities in acoustical impedance at the baffle-strip and strip-baffle interfaces. The radiated pressure is highest around the baffle-strip interface, but decreases toward the strip-baffle interface where the plane wave distortion reduces accordingly. As the unperturbed and radiated waves have different magnitudes and superimpose out of phase, the surface pressure and intensity increase across the strip in the plane wave propagation direction. Therefore, the surface absorption of the strip is nonzero and nonuniform. This paper provides an understanding of the surface pressure and intensity behaviors of a finite impedance strip for a grazing incident plane wave, and of how the distributed intensity determines the sound absorption coefficient of the strip.

Acute Triangulations of Flat Mobius Strips

In this paper we investigate the acute triangulations of flat Mobius strips. We find out that we can always triangulate a flat Mobius strip with at most nine acute triangles, and sometimes (but not always) that many triangles are really needed.

Fibrillatory conduction in branching atrial tissue—Insight from volumetric and monolayer computer models

Increased local load in branching atrial tissue (muscle fibers and bundle insertions) influences wave propagation during atrial fibrillation (AF). This computer model study reveals two principal phenomena: if the branching is distant from the driving rotor ( > 19 mm), the load causes local slowing of conduction or wavebreaks. If the driving rotor is close to the branching, the increased load causes first a slow drift of the rotor towards the branching. Finally, the rotor anchors, and a stable, repeatable pattern of activation can be observed. Variation of the bundle geometry from a cylindrical, volumetric structure to a flat strip of a comparable load in a monolayer model changed the local activation sequence in the proximity of the bundle. However, the global behavior and the basic effects are similar in all models. Wavebreaks in branching tissue contribute to the chaotic nature of AF (fibrillatory conduction). The stabilization (anchoring) of driving rotors by branching tissue might contribute to maintain sustained AF.

Downstream and soaring interfaces and vortices in 2-D stratified wakes and their impact on transport of contaminants

Abstract. The flow of continuously stratified fluids past obstacles was studied analytically, numerically, and experimentally. The obstacles discussed here include a flat strip, aligned with the flow, inclined or transverse to the flow and a horizontal cylinder. In the flow pattern, transient and attached (lee) internal waves, downstream wakes with submerged interfaces and vortices, soaring singular interfaces, soaring vortices and vortex systems are distinguished. New components of laminar flow past a horizontally towed strip are presented. Fine transverse streaky structures on the strip in the downstream wake were visualized. Soaring isolated interfaces, which are internal boundary layers forming inside the downstream attached wave field past bluff bodies were observed. With increasing of the body velocity a vortex pair was formed directly at the leading edge of this interface.

Osteoblast proliferation on neat and apatite-like calcium phosphate-coated titanium foam scaffolds

The biocompatibility and the load-bearing ability of lightweight titanium made it possible to be used as a biomaterial, especially in hip revision and fixation surgery. It was initially shown that sand-blasted or surface-roughened titanium implants had an improved bone-bonding ability over the bioinert metallic surfaces. Plasma-spraying of a phase mixture of loosely-attached calcium phosphates on titanium implants further improved their in vivo bone-bonding ability. However, stoichiometric calcium hydroxyapatite ceramic of high crystallinity is known to have poor in vivo resorbability, and is shy of taking part in bone remodeling and of being resorbed by the osteoclasts. Supersaturated calcium phosphate (CaP) solutions, such as synthetic body fluids (SBF), on the other hand, are able to form “carbonated, hydrophilic and apatite-like” CaP nanoaggregates on titanium surfaces. A Tris-buffered SBF solution with an HCO 3 − concentration of 27 mM was used in this study. Neat, NaOH-etched, and SBF-coated (biomimetic coating) titanium foams were compared with in vitro cell culture experiments by using rat osteoblasts. SBF-coated foams were found to yield the highest protein concentration at the end of the in vitro culture tests. Such biomimetic coatings were easily formed on flat strips, springs, or 3D foams of titanium, without any geometric constraints. The coated titanium springs and foams were characterized by using XRD, SEM, and FTIR.