Three-layer Theory Research Articles

Dr. Preedee’s Three-Layer Theory of Law

First published in Somyot Chuathai (ed.), Essays in Honour of Preedee Kasemsup, Faculty of Law, Thammasat University, 1988. Translated by Adam Reekie Translator’s Introduction The late Dr Preedee Kasemsup ranks among the most distinguished Thai legal scholars of the 20th century. Although his work covers many fields of law, including legal philosophy and jurisprudence, legal methods and legal history, perhaps his greatest contribution to Thai legal thought is his “three-layer theory of law.” Professor Preedee spent decades, roughly in the 1970s-80s, developing this theory which became a hallmark of the ‘Thammasat School’ of legal scholarship. The three-layer theory of law represents a firmly socio-cultural approach to law and legal history, which recognises a multiplicity of sources of law and the dynamic and complex nature of legal development. Furthermore, it serves as a principled basis to challenge assumptions about superiority of ‘modern law’ and to expose fallacies concerning legal positivism and constructivism, while also drawing attention to the challenges for legal scholars in legal interpretation, given the law’s plurality of sources. Some discussion of the three-layer theory of law has already been published in English. Professor Preedee’s book chapter “Reception of Law in Thailand – a Buddhist Society”[1] is an application of this theory to the process of reception of legal ideas in Thailand in the 19th-20th centuries, and a frequently referenced source for English-language research into Thai legal history. However, this article, written by the eminent scholar Somyot Chuathai and published in 1988, represents a succinct but detailed account of the conceptual underpinnings of the theory as well as an overview of some of its implications. It is hoped that this translation will be of interest to students and scholars as an important and widely influential work of Thai legal thought. [1] Preedee Kasemsup, "Reception of Law in Thailand – a Buddhist Society" in Masaji Chiba (ed), Asian Indigenous Law: In Interaction with Received Law (London: KIP Limited, 1986) 267-300

Multi-objective genetic algorithm optimization of composite sandwich plates using a higher-order theory

The main purpose of this paper is multi-objective optimization of soft-core composite sandwich plates using a known accurate high-order sandwich plate theory. In this three-layer theory, high-order kinematic assumptions are dedicated to each face sheet and the core layer. This theory considers the transverse flexibility of the soft core and satisfies transverse shear stresses continuity conditions and zero transverse shear stresses conditions at the upper and lower surfaces of the plate. The governing equations for bending and buckling analyses are derived using Hamilton’s principle, and their analytical solutions are presented for cross-ply plates. Two multi-objective optimization problems consist of weight/deflection optimization and weight/buckling load optimization of the unidirectional and cross-ply sandwich plates being studied. The thicknesses of the core and the face sheet layers are set as problems variables. The genetic algorithm is employed to find the optimal solutions for the problems, and the results are presented in form of the Pareto front. The accuracy of the present modeling and optimization method is evaluated for special case of buckling load maximization of laminated composite plates. For each problem, the optimization process is continued for more than 200 generations, but the results don’t change after 100 generations and the optimized results are obtained. The results confirm that there is no significant difference between the optimal solutions of unidirectional and cross-ply sandwich plates in both optimization problems. The process statistics show that cross-ply layup optimization takes about 25% more time than the unidirectional layup.

Laboratory investigations on the resonant feature of \u2018dead water\u2019 phenomenon

Interfacial internal wave excitation in the wake of towed ships is studied experimentally in a quasi-two-layer fluid. At a critical ‘resonant’ towing velocity, whose value depends on the structure of the vertical density profile, the amplitude of the internal wave train following the ship reaches a maximum, in unison with the development of a drag force acting on the vessel, known in the maritime literature as ‘dead water’. The amplitudes and wavelengths of the emerging internal waves are evaluated for various ship speeds, ship lengths and stratification profiles. The results are compared to linear two- and three-layer theories of freely propagating waves and lee waves. We find that despite the fact that the observed internal waves can have considerable amplitudes, linear theories can still provide a surprisingly adequate description of subcritical-to-supercritical transition and the associated amplification of internal waves. We argue that the latter can be interpreted as a coalescence of frequencies of two fundamental stable wave motions, namely lee waves and propagating interfacial wave modes.Graphic abstract

Transient response of sandwich plate with transversely flexible and viscoelastic frequency-dependent material core based on a three-layered theory

In this paper, the dynamic response of a simply supported sandwich plate with viscoelastic transversely flexible core is investigated, analytically using three-layered sandwich plate theory. Hamilton’s principle is employed to obtain governing equations of motion. Also, GHM (Golla–Hughes–McTavish) method is used to model the Frequency-Dependent Material properties of viscoelastic core. Modal superposition method is used to convert partial differential equations of motion to ordinary differential equations with time varying coefficients. Newmark approach is applied to solve the ordinary differential equations, numerically. Results of dynamic analysis in the present model are validated by the results published in the literatures. The natural frequencies and modal loss factors of the sandwich plate are extracted at 30°C and 90°C and effects of geometrical parameters are discussed. The advantages of the GHM model over the classical models such as Kelvin–Voigt are illustrated. The obtained results show that GHM model presents a more accurate description of transient response of the sandwich plate with viscoelastic core by considering the frequency dependency behavior of viscoelastic material. Core flexibility causes a difference between deflection of lower and upper surfaces, so that the three-layered sandwich theory will lead to more exact results with a remarkable deviation from the high-order single-layered theory.

Low-Convection-Cooling Slope Cast AlSi7Mg Alloy: A Rheological Perspective

In this paper we made an attempt to assess the solidification and flow behavior of the AlSi7Mg alloy melt flowing down the cooling slope, by calculating the Reynolds number of the flowing melt. It has been found that the length of the laminar regime within the flowing melt (low-convection flow) depends on the angle of slope. The microstructure of as-cast AlSi7Mg alloy processed by low-convection-casting using cooling slope method has been studied. The microstructure reveals dendritic primary α-Al phase with fine fibrous eutectic silicon in the interdendritic regions. The modification of eutectic silicon occurs predominately by the shearing of the solute-rich liquid between the primary α-Al dendrites prior to eutectic solidification as it flows down the cooling slope. Nucleation and growth of the primary silicon dendrites was also observed, which confirms earlier reports on three-layer theory. The mechanism responsible for the refinement of eutectic phase is the enhanced heterogeneous nucleation in the last liquid to solidify.

High-order free vibrations of doubly-curved sandwich panels with flexible core based on a refined three-layered theory

Abstract There are few reports on the free vibration of soft core doubly-curved sandwich shells. Previous studies are largely based on the equivalent single layer theories in which the natural frequencies are grossly overestimated. This study deals with the analytical free vibrations of doubly curved sandwich shell with flexible core based on a refined general-purpose sandwich panel theory. In this theory, equations of motion are formulated based on displacements and transverse stresses at the interfaces of the core. The first order shear deformation theory and assumptions of linear distribution of transverse normal stress and uniform shear stresses over the thickness of core (based on 3D-elasticity solution of weak core) are used in the present theory. In this model, the in-plane displacements take cubic polynomial distributions and the transverse displacement has a quadratic one thorough the core thickness. Hamilton’s principle is used to obtain the equations of motion. The obtained results are validated by the analytical and numerical results published in the literatures. Parametric study is also included to investigate the effects of radius of curvature, thickness and flexibility of core.

Theory of passive permeability through lipid bilayers.

Recently measured water permeability through bilayers of different lipids is most strongly correlated with the area per lipid A rather than with other structural quantities such as the thickness. This paper presents a simple three-layer theory that incorporates the area dependence in a physically realistic way and also includes the thickness as a secondary modulating parameter. The theory also includes the well-known strong correlation of permeability upon the partition coefficients of general solutes in hydrocarbon environments (Overton's rule). Two mathematical treatments of the theory are given; one model uses discrete chemical kinetics and one model uses the Nernst-Planck continuum equation. The theory is fit to the recent experiments on water permeability in the accompanying paper.

Effects of surface physical sorption on characteristic of coated quartz-crystal humidity sensor

A three-layer mechanical model, which consists of a quartz layer, a solid film layer and a fluid-phase film layer, is presented and a formula is deduced for calculating the relationship between the surface state and frequency shift of a quartz-crystal resonator. The theory has been used to analyse the characteristic of a resonant humidity sensor using a coated quartz-crystal resonator. Experiments prove that the new deduced formula gives better agreement with experimental results than Sauerbrey's formula. Furthermore, the three-layer theory can be widely used in developing sensors constructed with quartz-crystal resonators.

Mesolayer theory for turbulent flows

ONG and Chen,1 Afzal,2'3 and Afzal and Bush4 have reported the intermediate layer theory for turbulent shear flows. The velocity in the intermediate (meso) layer, as postulated by Long and Chen,1 is of the order of the friction velocity. The inner and intermediate layers in the mesolayer theory1 were regarded as a composite expansion that was matched with the outer defect layer. Their theory showed that for a boundary layer the logarithmic region was absent and that for a pipe flow the effect of the mesolayer was weak, although it did tend to modify the classical logarithmic behavior. In contrast to Long and Chen, Afzal2'3 has shown that the velocity in the intermediate layer is of the order of unity. Afzal's theory2'3 dealt separately with three (inner, intermediate, and outer) layers that were matched in the two overlap domains to show the possibility of two logarithmic regions rather than the one proposed by classical theory. Afzal2'3 and Afzal and Bush4 have shown that, in terms of classical theory, there is a distinct intermediate limit between the outer defect layer and the inner wall layer. This (new) three-layer theory modifies and/or extends the (old) two-layer theory. The implications of turbulent modeling by eddy viscosity and mixing length have been studied by Afzal and Bush.4 The aim of this Note is to modify Long and Chen's mesolayer theory in the light of Afzal's proposition2'3 that the velocity in the intermediate layer is of the order of C/ c, where 0 ( U c) >0 ( UT ). On the basis of the above stated proposition, a composite expansion for the inner and intermediate layer is formulated. The composite expansion is matched with the outer defect layer to show that the classical logarithmic region always exists, provided Uc is judiciously selected. It is further shown that the intermediate layer, when analyzed in terms of the two-layer classical theory, plays an insignificant role as far as the lowest-order results are concerned. However, this intermediate layer plays a significant role in the first-order theory where a three-layer picture of the flow is required.

THE COMPLEMENT-DEPENDENT BACTERIOLYTIC ACTIVITY OF NORMAL HUMAN SERUM: II. CELL WALL COMPOSITION OF SENSITIVE AND RESISTANT STRAINS

A comparative study has been made of the chemical composition of cell walls from two strains of Escherichia coli—one rough strain which was very sensitive to killing and lysis by normal human serum, and one smooth strain which was relatively insensitive to killing and was not lysed at all. The major components in the cell walls of both strains were protein and (or) polypeptide (70–80%) and lipid (14%), no significant differences in either component being detected between the two strains. A marked difference was, however, detected in the lipopolysaccharide fraction which was present to the extent of only 1% in the walls of the rough, serum-sensitive strain and 9% in the smooth, serum-resistant strain. Moreover, the two lipopolysaccharides were qualitatively different in sugar composition, that from the resistant strain yielding glucose, galactose, rhamnose, and two minor sugar components, while that from the sensitive strain yielded glucose only. These findings are discussed in relation to the three-layer theory for the structure of the coli cell wall and in relation to the serum factors (antibody, properdin, complement, and lysozyme) which may participate in the destruction of bacteria by serum.