The compressibility properties of systems consisting of generic tetragonal beam structures are analyzed and discussed. It is shown that these systems can exhibit negative linear compressibility (i.e. ...NLC) for certain conformations, that is, the systems with particular geometry will expand along one direction when compressed hydrostatically. It is also shown that through carefully choosing the geometric features, one may control the magnitude and range of NLC.
We studied recent observation data of pulsar masses and radii of PSR J0740+6620, PSR J0348+0432, and PSR J1614–2230 from different measurements, based on the extended version of σ-ω model. Throughout ...our analysis, we assumed that these pulsars are maximal-mass compact stars, thus we applied the core approximation. Based on the linear relation between the microscopic and macroscopic parameters of compact stars evaluated by our model, we estimated the average Landau mass m
L
= 752.46
- 42.5
+ 49.1
MeV and compressibility K = 261.7
- 28.0
+ 57.2
MeV.
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Mechanical metamaterials are man-made structures with counterintuitive mechanical properties that originate in the geometry of their unit cell instead of the properties of each ...component. The typical mechanical metamaterials are generally associated with the four elastic constants, the Young's modulus E, shear modulus G, bulk modulus K and Poisson's ratio υ, the former three of which correspond to the stiffness, rigidity, and compressibility of a material from an engineering point of view. Here we review the important advancements in structural topology optimisation of the underlying design principles, coupled with experimental fabrication, thereby to obtain various counterintuitive mechanical properties. Further, a clear classification of mechanical metamaterials have been established based on the fundamental material mechanics. Consequently, mechanical metamaterials can be divide into strong-lightweight (E/ρ), pattern transformation with tunable stiffness, negative compressibility (−4G/3 < K < 0), Pentamode metamaterials (G ≪ K) and auxetic metamaterials (G ≫ K), simultaneously using topology optimisation to share various fancy but feasible mechanical properties, ultralight, ultra-stiffness, well-controllable stiffness, vanishing shear modulus, negative compressibility and negative Poisson’s ratio. We provide here a broad overview of significant potential mechanical metamaterials together with the upcoming challenges in the intriguing and promising research field.
Natural gas hydrate is a new alternative energy that has attracted global attention in recent years. Depressurization is considered a fundamental method of producing natural gas from gas ...hydrate-bearing sediments (GHBSs). However, soil compaction during depressurization is a significant problem for production efficiency and safety. The compressibility of soil affects the hydrate dissociation in the coupled process of heat transfer, fluid flow, and soil compaction. In this study, a fully coupled Thermo-hydro-chemo-mechanical (THCM) model is applied to simulate Masuda's core-scale gas production experiments. The effects of compressibility on the changes in gas production rate, pore pressure, temperature, hydrate saturation, permeability, and heat conductivity are investigated by varying the parameters governing compressibility including the bulk modulus of host sediments and hydrate-enhanced bulk modulus. The results show that the higher compressibility corresponds to a larger reduction in porosity further impacting the variation in effective permeability, heat conductivity, and heat convection during depressurization. In Masuda's test, the pressure changes indicate that the soil compaction might occurs during depressurization. Because the real field production is implemented under confining condition, Masuda's test should be developed to consider the compressibility of GHBSs.
•Soil compaction indirectly affects heat transfer by decreasing the porosity.•The compressibility of host sediment affects gas production more than the enhanced compressibility by hydrate.•The effective permeability is modified to consider both soil compaction and hydrate dissociation.•Soil compaction may happen in Masuda's core-scale experiment.
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