Illustrating Membrane-Dominated Regimes in Pressurized Thin Shells

Pressurized thin-wall structures cover a broad range of applications, including storage tanks, pressurized rubber flood barriers, and large span enclosures. To accurately model such structures, the analyst must select the appropriate mechanical formulation (e.g.membrane vs shell). Membranes are assumed to have negligible bending stiffness and respond to compression by wrinkling; shells resist axial compression (before buckling) and bending efficiently. While theoretical research on these differences is vast, this study aims to explicitly clarify the consequences of this choice and permit a comparison of error between membrane and shell formulations. Therefore, this paper presents a parametric study of canonical pressurized thin-wall structural geometries (i.e.semi-cylinder, hemisphere) to illustrate the transitions between membrane and bending dominant behavior. The mathematical models of a pneumatic 5-parameter shell and membrane are presented and employed to quantify the effects of variables such as thickness and geometry on the amount of membrane, bending, and shear energy. The effects of inflation pressure, self-weight, and hydrostatic loads are also considered. The graphical results, presented in terms of dimensionless quantities in the design space, are general and should be of interest to the theorist and practitioner alike.

Optimization of the Mechanical Formulation of Typha Concrete

In order to address energy efficiency issues in the building sector, we conducted this study which focuses on the optimization of the mechanical characteristics of Typha concrete for its use in load-bearing structures of buildings. The fact that buildings are very energy-intensive makes it essential to develop new forms of construction based on bioclimatic architecture and the valorization of certain materials considered as waste in construction. To achieve these objectives, wehave targeted the use of Typha Australis thanks to its great availability and high thermalinsulation capacity. Thus, starting from the composition of a control concrete determined bythe DreuxGorisse formulation method with a characteristic compressive strength of 20 MPaat 28 days, Typha S1 series concretes are formulated with the substitution of sand up to 40, 50,and 60% of Typha. In order to increase the mechanical strength of Typha S1 series concretes,the cement class and G/S ratio are increased for the second S2 series.At the end of this research, the results obtained show that some of these concretes withdifferent proportions of Typha have good mechanical performance, which depends on theirstructural use.

Making a dart for a clothing pattern in virtual space

PurposeThe final goal of this study is to virtualize draping. Draping which is one of the methods to design paper patterns for clothing requires much labor and time. The sub-goal of this study is to construct a system in which the fundamental functions of draping are equipped.Design/methodology/approachThe system is realized in the virtual world by integrating the virtualized elements of real draping. The cloth is modeled by mechanical formulation, and the shape is determined by numerical calculation. The hand is geometrically modeled, and the captured motions of the hand and fingers are applied to the model. The model dress form is made from the data by measurement. The system in which darts can be made in the virtual space is constructed by integrating the models.FindingsIt is confirmed that the cloth model in the virtual world can be manipulated by the motions of the fingers in the real world. And it is suggested that it is possible to design practical paper patterns for clothing by adding functions to the system.Originality/valueWe are aiming at the system to design paper patterns by the movements of the fingers. With this system, it is expected that the efficiency in designing paper patterns is much improved, and it becomes possible to design clothing that fits individuals efficiently.

Sum frequency generation, calculation of absolute intensities, comparison with experiments, and two-field relaxation-based derivation

The experimental sum frequency generation (SFG) spectrum is the response to an infrared pulse and a visible pulse and is a highly surface-sensitive technique. We treat the surface dangling OH bonds at the air/water interface and focus on the absolute SFG intensities for the resonant terms, a focus that permits insight into the consequences of some approximations. For the polarization combinations, the calculated linewidths for the water interface dangling OH SFG band at 3,700 cm−1 are, as usual, too large, because of the customary neglect of motional narrowing. The integrated spectrum is used to circumvent this problem and justified here using a Kubo-like formalism and theoretical integrated band intensities rather than peak intensities. Only relative SFG intensities are usually reported. The absolute integrated SFG intensities for three polarization combinations for sum frequency, visible, and infrared beams are computed. We use molecular dynamics and the dipole and the polarizability matrix elements obtained from infrared and Raman studies of H2O vapor. The theoretical expressions for two of the absolute susceptibilities contain only a single term and agree with experiment to about a factor of 1.3, with no adjustable parameters. The Fresnel factors are included in that comparison. One of the susceptibilities contains instead four positive and negative terms and agrees less well. The expression for the SFG correlation function is normally derived from a statistical mechanical formulation using a time-evolving density matrix. We show how a derivation based on a two-field relaxation leads to the same final result.

Consolidation of gas hydrate-bearing sediments with hydrate dissociation

Quantifying sediment deformation induced by depressurization of gas hydrate reservoirs and hydrate dissociation is crucial for the safe and economic production of natural gas from hydrates, and for understanding hydrate-related natural geological risks. This study uses our recently developed fully-coupled Thermo-Hydro-Mechanical formulation for gas hydrate-bearing geological systems implemented in the 3D Code_Bright simulator. First, the model formulation is briefly presented. Then, the model is applied to reproduce published experimental consolidation tests performed on hydrate-bearing pressure-core sediments recovered from the Krishna–Godavari Basin (offshore of India) during the India National Gas Hydrate Project Expedition 02 (NGHP02). The numerical simulation reproduces the tests in which the sediment is loaded and unloaded prior and after hydrate dissociates via depressurization at constant effective stress. Our results successfully capture sediment collapse when hydrate dissociates at a mean effective stress above that of the host sediment consolidation curve. The mechanical constitutive model Hydrate-CASM also allows reproducing the experimentally observed changes in sediment swelling index with changes in hydrate saturation.

Quantum Structure for Modelling Emotion Space of Robots

Utilising the properties of quantum mechanics, i.e., entanglement, parallelism, etc., a quantum structure is proposed for representing and manipulating emotion space of robots. This quantum emotion space (QES) provides a mechanism to extend emotion interpretation to the quantum computing domain whereby fewer resources are required and, by using unitary transformations, it facilitates easier tracking of emotion transitions over different intervals in the emotion space. The QES is designed as an intuitive and graphical visualisation of the emotion state as a curve in a cuboid, so that an “emotion sensor” could be used to track the emotion transition as well as its manipulation. This ability to use transition matrices to convey manipulation of emotions suggests the feasibility and effectiveness of the proposed approach. Our study is primarily influenced by two developments. First, the massive amounts of data, complexity of control, planning and reasoning required for today’s sophisticated automation processes necessitates the need to equip robots with powerful sensors to enable them adapt and operate in all kinds of environments. Second, the renewed impetus and inevitable transition to the quantum computing paradigm suggests that quantum robots will have a role to play in future data processing and human-robot interaction either as standalone units or as part of larger hybrid systems. The QES proposed in this study provides a quantum mechanical formulation for quantum emotion as well as a platform to process, track, and manipulate instantaneous transitions in a robot’s emotion. The new perspective will open broad areas, such as applications in emotion recognition and emotional intelligence for quantum robots.

Quantum mechanical study of the high-temperature H+ + HD → D+ + H2 reaction for the primordial universe chemistry

ABSTRACT We use the time-independent quantum-mechanical formulation of reactive collisions in order to investigate the state-to-state H+ + HD → D+ + H2 chemical reaction. We compute cross-sections for collision energies up to 1.8 eV and rate coefficients for temperatures up to 10 000 K. We consider HD in the lowest vibrational level v = 0 and rotational levels j = 0–6, and H2 in vibrational levels v′ = 0–3 and rotational levels j′ = 0–9. For temperatures below 4000 K, the rate coefficients strongly vary with the initial rotational level j, depending on whether the reaction is endothermic (j ≤ 2) or exothermic (j ≥ 3). The reaction is also found less and less probable as the final vibrational quantum number v′ increases. Our results illustrate the importance of studying state-to-state reactions, in the context of the chemistry of the primordial universe.

Thermo-Hydro-Mechanical Coupled Modeling of Methane Hydrate-Bearing Sediments: Formulation and Application

We present a fully coupled thermo-hydro-mechanical formulation for the simulation of sediment deformation, fluid and heat transport and fluid/solid phase transformations occurring in methane hydrate geological systems. We reformulate the governing equations of energy and mass balance of the Code_Bright simulator to incorporate hydrate as a new pore phase. The formulation also integrates the constitutive model Hydrate-CASM to capture the effect of hydrate saturation in the mechanical response of the sediment. The thermo-hydraulic capabilities of the formulation are validated against the results from a series of state-of-the-art simulators involved in the first international gas hydrate code comparison study developed by the NETL-USGS. The coupling with the mechanical formulation is investigated by modeling synthetic dissociation tests and validated by reproducing published experimental data from triaxial tests performed in hydrate-bearing sands dissociated via depressurization. Our results show that the formulation captures the dominant mass and heat transfer phenomena occurring during hydrate dissociation and reproduces the stress release and volumetric deformation associated with this process. They also show that the hydrate production method has a strong influence on sediment deformation.