Structural Similitude Research Articles

Crystallization studies on linear aliphatic n‐polyurethanes

AbstractA detailed crystallization study of the linear n‐polyurethane (n‐PUR) family for n ranging from 5 to 12 was carried out by DSC supported by polarizing optical microscopy. The study embraces crystallization of all the n‐PUR under both nonisothermal and isothermal conditions. The odd and even series of n‐PUR defined by the parity of the number of methylenes (n) contained in the polymer repeating unit are considered and separately analyzed. All the members of the two series showed a thermal behavior consistent with their chemical constitution. Isothermal crystallization data were analyzed by the kinetics Avrami approach which revealed that the “crystallizability” of n‐PUR increases steadily with the flexibility of the polyurethane chain. Melting and enthalpy temperatures of isothermally and nonisothermally crystallized n‐PUR were found to vary with n according to a zig‐zag plot characteristic of odd–even effect. Given the structural similitude of n‐PUR with (n + 2)‐nylons, results were referenced to those reported for this family of polyamides. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1368–1380, 2009

Structural Similitude for Buckling of Delaminated Beams

A significant amount of research has been conducted on the buckling behavior of delaminated composite laminates. However, none of the investigations has been focused on establishing similarity and scaling laws for buckling response of composite laminated with delamination. The main objective of this study is to demonstrate the applicability of similitude theory in designing scaled down models for predicting the buckling behavior of delaminated laminated beam subjected to uni-axial compression. The results presented herein indicate that, for buckling response of delaminated beam-plates, based on structural similitude, a set of scaling laws can be found which use to develop design rules for small scale models. For models with the same material properties and stacking sequence as prototype, distorted models with different number of delaminations, delamination length and depth than those of the prototype can predict the behavior of the prototypes with good accuracy.

Taxonomy of Liturgy and Theatre: Structural Similitude

Taxonomy of Liturgy and Theatre: Structural Similitude

Low-energy excitation spectra and excitonic condensate state in strong correlated antiferromagnetic systems

The strongly correlated antiferromagnetic lattices can be the scenario for different states of matter. The interactions causing the different situations within these systems are the Kondo exchange and the Heisenberg interaction within a localized spin field. In this work, we analyze the low-energy excitation states of such lattices in any dimension, considering these two interactions in an antiferromagnetic insulator background. These states can be obtained from the associations of fermionic states with spin fluctuation waves. Such composite states interact via the two types of exchange, and their locations and ${E}_{\mathbf{k}}$ dispersions allow one to analyze the main features of the system. For certain values of the bandwidth of the noninteracting system $(\ensuremath{\delta})$ and the Kondo coupling parameter $({J}_{0})$, these composite states either are located within the antiferromagnetic gap, this implying a decrease in the insulating character, or can cross the Fermi level and a quantum phase transition can appear. Some denominated Kondo insulators and the normal state of some antiferromagnetic superconductors might be explained within this model. On the other hand, the charged-particle--magnon mixed states based on electrons and holes present attractive interactions and can then produce magnetic excitons. When these magnetic exciton states are located in the insulating gap, they constitute the lowest energy excitation spectra of the system. In an extreme case, the attractive interaction between the partners of these excitons can be the cause of the appearance of a new phase that presents structural similitude with an insulating Bose-Einstein condensate and a thermodynamic behavior similar to that of the BCS states. The special conditions for the appearance of this condensate are analyzed.

Structural Similitude and Scaling Laws for Sandwich Beams

Problems associated primarily with structural similitude as applied to sandwich beams and columns are investigated. Similitude theory is employed to develop the necessary similarity conditions or scaling laws. Scaling laws provide the relationship between a full-scale structure (prototype) and its scaled down model. These relationships can be used to design the small-scale model and to extrapolate the experimental data of the model to predict the behavior of the large prototype. Note that scaled down models are inexpensive and easily tested. The developed methodology is demonstrated through analysis of the bending of sandwich beams subjected to transverse loads, and it is totally analytical. A small model is designed and theoretically analyzed. The theoretically obtained responsepredictions are treated as if they wereexperimentally obtained (from model testing ). Then, scaling laws are used with the model data to predict the behavior of the large prototype. Finally, these predictions are compared to the theoretically obtained response of the prototype to test the validity of the method. Predicted and theoretical response is very close, and therefore, the demonstration is successful. Both complete (satisfaction of all similarity conditions) and partial similarity are discussed. Nomenclature bwk = width of panel ck = thickness of the core dtk;dbk = thickness of the upper and the lower skin, respectively EAtk;EAbk = longitudinal rigidities of the upper and the lower face, respectively Eck; Gck = vertical modulus of elasticity of the core and its shear modulus, respectively EIk = e exural rigidity of beam EItk;EIbk = e exural rigidities of upper and lower faces, respectively k = p or m, where p refers to the prototype and m to the model

Structural similitude and scaling laws for sandwich beams

Structural similitude and scaling laws for sandwich beams

Structural similitude for flat laminated surfaces

Due to special characteristics of advanced reinforced composite materials, they require extensive experimental evaluation. Thus, it is extremely useful to use available experimental data of specific structural systems or of small-scale models to predict the behavior of all similar systems, especially large. This study investigates problems associated primarily with the design of scaled-down models. Similitude theory is employed to develop the necessary similarity conditions. Scaling laws provide the relationship between a full-scale structure and its scale models and can be used to extrapolate the experimental data of a small, inexpensive, and easily tested model into design information for the large prototype. Both complete and partial similarity is discussed. The developed method is demonstrated through analysis of the cylindrical bending of orthotropic laminated beamplates subjected to transverse loads, buckling of symmetric laminated cross-ply rectangular plates subjected to uniaxial compression and analysis for the vibration response of cross-ply symmetric configurations. For the case of beamplates, experimental data are available for a number of configurations and are used to test the validity of the methodology. In the buckling and vibration studies, the demonstration is totally analytical. In these cases, a small-scale model is theoretically analyzed, the theoretical predictions are treated as if they were experimental results, the scaling laws are then used to predict the behavior of the large prototype and finally these predictions are compared to the theoretical values of the prototype in order to test the validity of the method. All was accomplished with considerable success.

Structural similitudes between cytotoxic antiestrogen-binding site (AEBS) ligands and cytotoxic sigma receptor ligands. evidence for a relationship between cytotoxicity and affinity for AEBS or sigma-2 receptor but not for sigma-1 receptor

1-Benzyl-4-(N-2-pyrrolidinylethoxy)benzene (PBPE) is a cytotoxic derivative of the antitumoral drug tamoxifen. PBPE binds with high affinity and specificity to the microsomal antiestrogen-binding site (AEBS). PBPE, as well as some other high-affinity AEBS ligands, shares structural features with high-affinity and selective sigma receptor ligands in the N-(arylethyl)-N-alkyl-2-(1-pyrrolidinyl)ethylamine class, such as BD1008, which are cytotoxic against tumoral cells. Based on these structural and pharmacological similitudes, we set out to examine whether AEBS and sigma receptors could be related binding sites. We showed that BD1008 had a high affinity for AEBS. However, prototypical sigma receptor ligands were very low-affinity competitors on AEBS. Surprisingly, AEBS ligands displayed a high affinity for sigma-1 and sigma-2 receptor subtypes, showing that AEBS and sigma receptor-binding sites were not mutually exchangeable. Moreover, phenytoin, which is an allosteric modulator of sigma-1 receptor, was a competitive inhibitor of [3H]tamoxifen on AEBS. These results suggest that the tamoxifen-binding site on AEBS and the sigma ligand-binding site on sigma receptors were not identical but related entities. We also showed here that the high-affinity and specific AEBS ligands also bound sigma receptors with high affinity. Moreover, the compounds that were capable of displacing tamoxifen from AEBS were cytotoxic against tumoral cells but not against the AEBS-deficient cell line Rtx-6. These results confirm that AEBS and sigma receptors might belong to the same family of proteins, and that the tamoxifen-binding site might be involved in the cytotoxicity of AEBS ligands and some classes of sigma compounds.

Structural similitude for vibration response of laminated cylindrical shells with double curvature

In order to understand the applicability of scaled down models in designing laminated composite structures, an analytical investigation was undertaken to assess the feasibility of their use. Employment of similitude theory to establish similarity among structural systems can save considerable expense and time, provided the proper scaling laws are found and validated. The developed methodology is demonstrated through application of similitude theory to laminated cylindrical shells. Particular emphasis is placed on the case of free vibration of cross-ply laminated cylindrical shells with double curvature. The results presented herein indicate that, for free vibration responses of laminated cylindrical shells of double curvature, based on structural similitude, a set of scaling laws can be found which are used to develop design rules for designing small scale models. This analytical study indicates that distorted models with a different number of layers, geometries and material properties than those of the prototype can predict the behavior of the prototype with good accuracy. However, it is shown that a scaled down model with distorted curvature is incapable of predicting the response of the prototype.

Structural Similitude and Scaling Laws for Buckling of Cross-Ply Laminated Plates

The increasing use of laminated composite components for a wide variety of applications in aerospace, mechanical, and other branches of engineering requires extensive experimental evaluation of any new design. Thus, it is extremely useful if a fullscale structure can be replaced by a similar scaled-down model, which is much easier to work with. The objective of this study is to investigate problems associated with the design of scaled models. Similitude theory is employed to develop the necessary similarity conditions. Both complete and partial similarity are discussed. The procedure consists of systematically observing the effect of each parameter and corresponding scaling laws. Then acceptable intervals and limitations for these parameters and scaling laws are discussed. In each case, a set of valid scaling factors and corresponding response scaling laws that accurately predict the response of prototypes from experimental models is introduced. Particular emphasis is placed on the cases of buckling of rectangular cross-ply laminated plates under uniaxial compressive and shear loads. This analytical study indicates that distorted models with a different number of layers and different material properties and geometries from those of the prototype can predict the behavior of the prototype with good accuracy.

Design of scaled down models for stability of laminated plates

This study investigates problems associated with design of scaled down models. Similitude theory is employed to develop the necessary similarity conditions. Scaling laws provide the relationship between a full-scale structure and its scale models and can be used to extrapolate the experimental data of a small, inexpensive, and easily tested model into design information for the large prototype. Both complete and partial similarity are discussed. Particular emphasis is placed on the cases of buckling of rectangular symmetric angle-ply laminated plates under uniaxial compressive and shear loads. This analytical study indicates that distorted models with a different number of layers, material properties, and geometries than those of the prototype can predict the behavior of the prototype with good accuracy. A scaled-down (by a large factor) model, scale model, which can predict the structural behavior of the full-scale system, prototype, can prove to be an extremely beneficial tool. This possible develop- ment must be based on the existence of certain structural parameters that control the behavior of the structural system when acted upon by static and/or dynamic loads. If such structural parameters exist, a scaled-down replica can be built, which will duplicate the response of the full-scale system. The two systems are then said to be struc- turally similar. The term, then, that best describes this similarity is structural similitude. Similitude theory is employed to develop the necessary similarity conditions (scaling laws). Scaling laws provide the relationship be- tween a full-scale structure and its scale models and can be used to extrapolate the experimental data of a small, inexpensive, and eas- ily tested model into design information for a large prototype. The difficulty of making completely similar scale models often leads to accept certain type of distortion from exact duplication of the prototype (partial similarity). Both complete and partial similarity are discussed. A parametric investigation of problems associated with designing small-scale models for cross-ply laminated wide beams1 and plates2 has been presented. The procedure consists of systematically observing the effect of each parameter and corre- sponding scaling laws. Then acceptable intervals and limitations for these parameters and scaling laws are discussed. In each case, a set of valid scaling factors and corresponding response scaling laws which accurately predict the response of prototypes from ex- perimental models is introduced. Particular emphasis is placed on the cases of buckling of rectangular angle-ply laminated plates un- der uniaxial compressive and shear loads. This analytical study also indicates that distorted models with a different number of layers, material properties, and geometries than those of the prototype can predict the behavior of the prototype with good accuracy. The objectives of the investigation described herein are twofold. The first is to derive the necessary similarity conditions in order to design a distorted model that accurately predicts prototype behav- ior including distortion in stacking sequence and number of plies (N) and ply-level and sublaminate-level scaling; distortion in ma- terial properties, E/;, v/y, and p and distortion in fiber orientation angle 0. The second is to evaluate the derived similarity conditions analytically. In all of our work in this area we will restrict ourselves to linearly elastic material behavior. Therefore, scale effects are not present. Furthermore, it is assumed that all laminas have equal thickness f, and the laminates are free of damage (delaminations, matrix crack- ing, fiber breaks, etc.).

Structural similitude for laminated structures

Due to special characteristics of advanced reinforced composite materials, they require extensive experimental evaluation. Thus, it is extremely useful to use available experimental data of specific structural systems to predict the behavior of all similar systems. This study describes the establishment of similarity conditions between two structural systems. Similarity conditions provide the relationship between a scale model and its prototype, and can be used to predict the behavior of the prototype by extrapolating the experimental data of the corresponding small scale model. Since satisfying all the similarity conditions simultaneously is in most cases impractical, distorted models with partial similarity (with at least one similarity condition relaxed) are employed. Establishing similarity conditions, based on direct use of governing equations, is discussed and the possibility of designing distorted models is investigated. The method is demonstrated through analysis of the cylindrical bending of othotropic laminated beamplates subjected to transverse loads and buckling of symmetric laminated cross-ply rectangular plates subjected to uniaxial compression.

Hydroelastic reduced scale model for wave-loaded compliant tower

Wave-basin test results from a reduced scale model for an offshore compliant tower for deep water is used to assess fluid-structure interaction effects and to calibrate finite-element models. The experimental model complies with the theoretical conditions of hydroelastic structural similitude and the fluid in which it is immersed is plain water. This latter feature allows for observation of rigid plus elastic body motions of the model both in still water and under waves. The techniques employed for physical modeling and experimental analysis are briefly outlined, dynamic characteristics and responses obtained from tests are reported and comparisons are made with their theoretical-numerical counterpart.

Estructura Interna Y Capacidad Predictiva de las Teorias Implicitas: Un Estudio Sobre la Mujer

ResumenEl propósito de esta investigación fue demostrar la similitud estructural entre las teorías implícitas y otros esquemas de conocimiento. Para ello, nos servimos de las creencias que tiene el hombre de la calle sobre la capacidad laboral de las mujeres. Después de observar la existencia de seis tipos de representaciones, la tradicional, la progresistas, la laboral, la biológica, la educacional y la psicológica, extrajimos 124 proposiciones causales de fuentes literarias, científicas e históricas.La primera investigación estudió el grado de pertenencia de las proposiciones a cada teoría mediante puntuaciones de tipicidad y polaridad, de acuerdo con la técnica de Rosch (1973). La dos siguientes probaron a través de un diseño factorial que la representación de las teorías generaba predicciones bien diferenciadas, tanto en conducta laboral como en elección vocacional.Los resultados se discuten contrastándolos con los obtenidos en los estudios sobre categorías naturales y scripts conductuales.

The pre-Cretaceous deep-seated tectonics of the Abukuma massif and its place in the structural framework of Japan

The structures and microstructures of the Takanuki and Hitachi areas in the Abukuma massif, Northeast Japan are described. In the Takanuki area, the basic Gosaisho series thrusts the pelitic Takanuki ones in a HP metamorphic context. The nappe structure is afterwards refolded by a migmatitic dome: the Samegawa dome, in a HT metamorphic context. Microtectonic analysis shows that the nappe was transported from south to north along the stretching lineation. Geometric features suggest that the Samegawa dome was emplaced by diapirism. The role of the thrust surface as an instable interface promoting the doming is emphasized. The Hitachi metamorphic rocks composed of basic schist, limestone and sandstone shist thrust the pelitic rocks of the western Hitachi gneisses. As for the Takanuki area, the thrusting occurred in ductile synmetamorphic conditions with a north or northeastward displacement. Owing to lithologic, petrologic, structural similitudes, the nappe of the Hitachi metamorphic rocks and that of the Gosaisho series are unified into a unique nappe with a northward motion. The emplacement occurred between late Permian and late Cretaceous likely in late Jurassic. The allochthonous units of the Abukuma massif are correlated with the Green Schist nappe described in Southwest Japan, since they are surrounded by the same zones, namely the Tanba zone and the Kurosegawa-Kitakami one. Moreover both in Southwest and Northeast Japan, the emplacement of the Green Schist nappes is due to a shear deformation inducing rotational structures along the stretching lineation indicating the same sense of transport, that is eastward in Southwest Japan and northward in Northeast Japan, owing to the late bending of the Japanese Islands. The late Jurassic nappe structure is obliquely overprinted by a HT metamorphism, Ryoke in Southwest Japan, Abukuma in Northeast Japan, and afterwards cut by late faults as the Median Tectonic Line or the Tanakura fault, giving rise to the present complexity.