Rigidity

A method is proposed for deriving dynamical equations for systems with both rigid and flexible components. During the derivation, each flexible component of the system is represented by a ``surrogate element'''' which captures the response characteristics of that component and is easy to mathematically manipulate. The derivation proceeds essentially as if each surrogate element were a rigid body. Application of an extended form of Lagrange''s equation yields a set of simultaneous differential equations which can then be transformed to be the exact, partial differential equations for the original flexible system. This method''s use facilitates equation generation either by an analyst or through application of software-based symbolic manipulation.

Expanded polystyrene (EPS) geofoam seismic buffers can be used to reduce earthquake-induced loads acting on rigid retaining wall structures. A numerical study was carried out to investigate the influence of wall height; EPS geofoam type, thickness, and stiffness; and excitation record on seismic buffer performance. The numerical simulations were carried out using a verified FLAC code. The influence of parameter values was examined by computing the maximum forces on the walls, the buffer compressive strains, and the relative efficiency of the buffer system. In general, the closer the predominant frequency of excitation to the fundamental frequency of the wall model, the greater the seismic loads and buffer compression. The choice of earthquake record is shown to affect the magnitude of maximum earth force and isolation efficiency. However, when the wall response for walls 3 to 9 m in height are presented in this study in terms of isolation efficiency, the data from scaled accelerogra...

Optimal cross-section design of beams plays a distinctive role which involve the rigidity of the member in bending, shear and torsion load conditions. Practically modern overhead crane girders, railway bridge girders or rail tracks etc. require constant cross-section along the axial direction as the load location changes all the time. Conventional topological optimization modeling procedures in such cases prove inadequate for the reason that these procedures generate non-uniform topologies along the axis of the bending member. To examine optimal topology of those structural bending members which commonly possess constant cross-section along the axis the topology optimization with extrusion manufacturing constraint is more appropriate. The extrusion constraint method suggests a fresh approach to investigate optimal topologies of beam cross-section under the influence of realistic loading condition across the section and along the beam at the beginning of design cycle. Presented study is focused upon the influence of various configuration and location of the load and boundary conditions on the topology of the of the beam cross-section which was not possible prior to the materialization of the extrusion or stamping constraint methods in Optistuct and TOSCA. Several realistic loads and boundary conditions including moving load condition have been applied on the 3D beam model and optimal cross-section topologies obtained have uniform compliance history and convergent solutions. The lowest compliance criteria have been suggested to choose topologies for furthers shape and size optimization candidates during beam design process.

According to the New Theory of Reference, proper names (and indexicals) and natural kind terms are semantically similar to each other but crucially different from definite descriptions and “ordinary” predicates, respectively. New Theorists say that a name, unlike a definite description, is a directly referential nondescriptional rigid designator, which refers “without a mediation of the content” and is not functional (i.e. lacks a Carnapian intension). Natural kind terms, such as ‘horse’ and ‘water’, are held to have similar distinctions, in contrast to other predicates. However, the New Theory contains some problems related to reference, descriptionality, content and meaning. In view of these problems, it will be argued that the distinctive shared feature of proper names and natural kind terms, while technically corresponding to nonfunctionality, is to be explicated in terms of independence of possible worlds, rather than in terms of reference and content: natural kind terms are world-independent predicates, making “worldless” predications. Just as, say, ‘Elvis’ names Elvis even with respect to “Elvisless” worlds, or, rather, names Elvis independently of worlds, natural kind terms are in an important sense “worldless” as well: to talk about Elvis is to talk about him irrespective of moments of time and possible worlds, and is to talk about a human, also irrespective of moments and worlds, while it is not to talk about, say, a drug-addict irrespective of moments, nor about a singer irrespective of worlds. There is no genuinely timeless and worldless predication of the sort “Elvis is (was) bald”, but there is, it seems, such a predication “Elvis is (was) human”. This notion of independence of times and worlds is detached from those of descriptionality and content mediation.

Neurotypical individuals cope flexibly with the full range of semantic relations expressed in human language, including metaphoric relations. This impressive semantic ability may be associated with distinct and flexible patterns of hemispheric interaction, including higher right hemisphere (RH) involvement for processing novel metaphors. However, this ability may be impaired in specific clinical conditions, such as Asperger syndrome (AS) and schizophrenia. The impaired semantic processing is accompanied by different patterns of hemispheric interaction during semantic processing, showing either reduced (in Asperger syndrome) or excessive (in schizophrenia) RH involvement. This paper interprets these individual differences using the terms Rigidity, Chaos and Integration, which describe patterns of semantic memory network states that either lead to semantic well-being or are disruptive of it. We argue that these semantic network states lie on a rigidity-chaos semantic continuum. We define these terms via network science terminology and provide network, cognitive and neural evidence to support our claim. This continuum includes left hemisphere (LH) hyper-rigid semantic memory state on one end (e.g., in persons with AS), and RH chaotic and over-flexible semantic memory state on the other end (e.g., in persons
with schizophrenia). In between these two extremes lie different states of semantic
memory structure which are related to individual differences in semantic creativity.
We suggest that efficient semantic processing is achieved by semantic integration, a
balance between semantic rigidity and semantic chaos. Such integration is achieved
via intra-hemispheric communication. However, impairments to this well-balanced and
integrated pattern of hemispheric interaction, e.g., when one hemisphere dominates the
other, may lead to either semantic rigidity or semantic chaos, moving away from semantic integration and thus impairing the processing of metaphoric language.

Proper estimation of soil reinforcement loads and strains is key to accurate internal stability design of reinforced soil structures. Current design methodologies use limit equilibrium concepts to estimate reinforcement loads for internal stability design of geosynthetic and steel reinforced soil walls. For geosynthetic walls, however, it appears that these methods are excessively conservative based on the performance of geosynthetic walls to date. This paper presents a new method, called the K-stiffness method, that is shown to give more accurate estimates of reinforcement loads, thereby reducing reinforcement quantities and improving the economy of geosynthetic walls. The paper is focused on the new method as it applies to geosynthetic walls constructed with granular (noncohesive, relatively low silt content) backfill soils. A database of 11 full-scale geosynthetic walls was used to develop the new design methodology based on working stress principles. The method considers the sti...

There is a certain popular argument, deriving from Ruth Barcan and Saul Kripke, from the conjunction of the Principle of the Indiscernibility of Identicals (PInI, for short) and the Principle of the Necessity of Self-Identity to the Thesis of the Necessity of Identity. My purpose is to show that this argument does not work, at least not in the form it is often presented. I also give a correct formulation of the argument and point out that PInI is not even needed in the argument for the necessity of identity.

Panarchy theory has been utilized to first conceptualize the entrenched conflict that lasted for nearly 30 years between Aceh and Indonesia and second, the development of peace prior to and shortly following the tsunami of 2004. The purpose of this paper is to show how panarchy or complex adaptive systems theory can be used to explain the previous
state of the Aceh-Indonesia conflict as a sustained maladaptive system and how it was eventually changed into an adaptive system harboring the potential for peaceful sustainability. There are four main questions that this thesis answers. First, how can the Aceh-Indonesia conflict be explained as a rigidity trap? Second, what were the main elements or inputs from cyclical systems below or above the Aceh-Indonesia conflict
scale that led to the collapse of the rigidity trap and the generation of a healthy or complex adaptive system? Third, what role, if any, did the tsunami of December 2004 play in achieving the peace of the new complex adaptive system and fourth, what elements or inputs into the new healthy system may or may not lead to the systems peaceful sustainability? The conflict and the peace achieved between the two former antagonists appears to be an example of a maladapted cyclical socio-economic and political rigidity trap that was acted upon by new inputs from cyclical scales above the Aceh-Indonesia conflict scale. It is thought that this is the first time panarchy theory has been applied to an aspect of conflict transformation modeling. It is hoped that this initial 4 attempt will encourage others to test panarchy theory; maladaptive and adaptive system models, in the field of conflict transformation.

The floating frame of reference formulation is currently the most widely used approach in flexible multibody simulations. The use of this approach, however, has been limited to small deformation problems. In this investigation, the computer implementation of the newabsolute nodal co-ordinate formulationand its use in the small and large deformation analysis of flexible multibody systems that consist of interconnected bodies are discussed. While in the floating frame of reference formulation a mixed set of absolute reference and local elastic co-ordinates are used, in the absolute nodal co-ordinate formulation only absolute co-ordinates are used. In the absolute nodal co-ordinate formulation, new interpretation of the nodal co-ordinates of the finite elements is used. No infinitesimal or finite rotations are used as nodal co-ordinates from beams and plates, instead, global slopes are used to define the element nodal co-ordinates. Using this interpretation of the element co-ordinates, beams and plates can be considered as isoparametric elements, and as a result, exact modelling of the rigid body dynamics can be obtained using the element shape function and the absolute nodal co-ordinates. Unlike the floating frame of reference approach, no co-ordinate transformation is required in order to determine the element inertia. The mass matrix of the finite elements is a constant matrix, and therefore, the centrifugal and Coriolis forces are equal to zero when the absolute nodal co-ordinate formulation is used. Another advantage of using the absolute nodal co-ordinate formulation in the dynamic simulation of multibody systems is its simplicity in imposing some of the joint constraints and also its simplicity in formulating the generalized forces due to spring-damper elements. The results obtained in this investigation show an excellent agreement with the results obtained using the floating frame of reference formulation when large rotation–small deformation problems are considered.