External Static Pressure Research Articles

Fabrication of Highly Sensitive Porous Polydimethylsiloxane Pressure Sensor Through Control of Rheological Properties.

In order to enhance the sensitivity of elastomers, pores were integrated into their structure. These pores facilitate the adjustment of thickness in response to external pressure variations, thereby improving the sensitivity of pressure sensors. Pores were introduced by emulsifying immiscible polydimethylsiloxane (PDMS) and water with a surfactant. By controlling the water content in the PDMS and water emulsion, we controlled the size, density, uniformity, and spatial distribution (2D or 3D) of the pores within the PDMS matrix. The presence of these pores significantly improved the sensitivity of PDMS under low external pressure conditions compared to high pressures. Specifically, porous PDMS exhibited approximately 10-times greater sensitivity under low-pressure conditions than non-porous PDMS. The effectiveness of porous PDMS was demonstrated through dynamic loading and unloading detection of a small Lego toy and monitoring of human heartbeats. These results highlight the efficacy of our pressure sensor based on porous PDMS, which is fabricated through a simple and cost-effective process using a PDMS and water emulsion. This approach is highly suitable for developing the ability to detect applied pressures or contact forces.

Skin-inspired self-powered tactile sensing textile with high resistance to tensile interference

Tactile sensors that can mimic the sensory capabilities of human skin to perceive external static and dynamic pressure without tensile interference are essential in smart wearable electronics. Here, inspired by human skin, we report a highly stretchable and conformable self-powered tactile sensing textile capable of precisely sensing the pressure with no influence of the extension. The tactile sensing textile consists of an elastic fabric substrate and a triboelectric nanogenerator network with specific dimensionally stable triangular cross knots, providing the textile with prominent comprehensive performances (high tactile sensitivity, high stretching-insensitivity, high pressure resolution, long-time stability, and washability) superior to other reported stretching-insensitive tactile sensors. A pressure sensing system is developed based on the tactile sensing textile, which presents wide application for precise pressure detection in smart wearable conditions including athletics and healthcare facilities.

Reassembling Post-Soviet Eurasia: Russia’s Leadership Potential in Conditions of External Pressure

The article examines the change in the world order and its geopolitical, geoeconomic, cultural and humanitarian consequences for Eurasian integration. The stages of transformation of the post-Soviet space after the collapse of the USSR are identified. The main risks for the countries of the region are characterized. It is concluded that medium-term challenges for integration processes include three areas: energy transition, information and communication revolution, including the expansion of digital platforms and the development of large language models, as well as the policy of the United States and other Western countries to contain and slow down the technological progress of Russia, China and other non-Western countries. These challenges pose a threat of consolidating post-Soviet Eurasia on the periphery of world development, but at the same time form the prerequisites for accelerating integration. Recommendations are given on the need to strengthen the scientific and technological direction of integration interaction with the leading role of Russia up to its approval as the main one within the EAEU. This process should be built on the basis of mutual benefit and strengthening trust, strengthening humanitarian cooperation between Russia and its partners in Eurasian integration.

Study of composite polymer degradation for high pressure hydrogen vessel by machine learning approach

AbstractThe aim of this article is to study the degradation of a composite material under static pressure. The high pressure condition is similar to the one encountered inside hydrogen tanks. Damage modeling was used to evaluate the behavior of hydrogen tanks to high pressure. A practical approach, coupling a finite element method (FEM) simulation and machine learning (ML) algorithm, is suggested. The representative volume element (RVE) was used in association with a choice of a behavior law and a damage law as an input data. Algorithms for ML classification such as K‐nearest neighbors (k‐NN) and a special k‐NN with a dynamic time warping metric were used. The hierarchical clustering through dendrograms visualizations allowed to exhibit the impact of composite parameters in relation to fiber, matrix properties and fiber volume fraction on the strain degradation under external static pressure. Continuing this, the optimum RVE which shows a low degradation value will be exhibited.

Comparative Investigation of Pressure Effect on Structural Stability, Electronic and Optical Response of LaXO<sub>3</sub> (X = Al, In, Ga) for Optoelectronic Applications

A first principle study intense on the density functional theory with Heydscuseria-Ernzerhof screened hybrid functional hybrid function (HSEO6) is used to assess the structural, Electronic, elastic, mechanical and optical responses of LaXO<sub>3</sub> (X = Al, In, Ga) perovskite materials. The compressive investigation under the external static isotropic pressure (P= 0 to 80GaP), phase stability, band structure and their important impact on the optical response of LaAlO<sub>3</sub>, LaInO<sub>3</sub> and LaGaO<sub>3</sub>. Electronic band structure shows that LaXO<sub>3</sub> (X = Al, In Ga) semiconductor with indirect band gap and an optically inactive response up to 20GPa, while the band gap becomes direct at 80GaP. There are gamma points (G-X-Q) at 80GPa and the band gap changes from indirect to direct nature. Under main desperation physical parameters of perovskite materials are well explained the response of TDOS, PDOS and EPDOS contour plots have been well understood for the full description of the band gap. It is further observed that the external pressure enhanced upto 40GPa both materials are significantly more mechanically stable compared to pristine LaXO<sub>3</sub> (X = Al, In, Ga) at 0GPa. The optical properties of LaAlO<sub>3</sub>, LaGaO<sub>3 </sub>and LaInO<sub>3</sub>, dielectric coefficient <i>(ε<sub>1</sub>, iε<sub>2</sub>)</i> have been employed along with the optical responses like absorption, energy loss function, reflectivity and reflective index are obtained in the energy scale from 0 to 60 eV. It was observed that static dielectric constant decreases with the decrease in optical band gap. The optical tunings under the effect of pressure which are good candidates in practical optoelectronic applications are extensively used and interpreted by the calculation of the dielectric function.

Effect of external static pressure on structural, electronic, and optical properties of 2-D hetero-junction MoS2 for a photocatalytic applications: A DFT study

Effect of external static pressure on structural, electronic, and optical properties of 2-D hetero-junction MoS2 for a photocatalytic applications: A DFT study

Assessment of factors of sustainability of manufacturing sector in industrial regions of Russia

Changing geopolitical environment in the world determines the chief priority of existence and development of the state, which is maintenance of the national sovereignty based on economic, technological and financial autonomy and independence. The basis of economic security of the country is the manufacturing sector. The study is devoted to identifying the ability of manufacturing sector of those industrial regions of Russia where manufacturing industry occupies a significant share of economics to maintain stability in conditions of external pressure since 2008 on the example of crises of various nature. The basic methods applied in the study are the indicative and comparative methods and the correlation analysis method. The authors present the analysis of the dynamics of the main indicators of development of the manufacturing sector of industrial regions of Russia, their investment and innovation activity in the industry and territorial perspective and the dependence of the regions’ development on foreign trade. It is pointed out that industrial regions are still of great significance in the development of manufacturing sector of the Russian Federation but their share in Russia is declining in such key indicators as gross regional product, volume of goods shipped, number of employees, etc. The authors conclude that in the majority of industrial regions high investment activity in manufacturing sector has greatly provided for sufficient resilience level which ensured rapid restoration of production volumes after 2008 crisis and smooth adaptation to the growing sanctions pressure that started in 2014. At the same time in nine of the 23 industrial regions under study, manufacturing sector was able to cope with the short-term shock of 2008 but prolonged impact of external factors that started in 2014 resulted in a slowdown in the trajectory of development. However, there is a risk of growing systematic character of the crisis in these regions, and it requires changing the approaches to the existing industrial policy and conducting additional analysis and assessment of the efficiency of the government support measures for manufacturing sector in order to develop the most effective industrial policy for every separate region. The results of the study can be useful for regional and federal authorities implementing economic and industrial policy.

Bond strength and confinement in reinforced concrete

The strength assessment of existing reinforced concrete structures is challenging when deterioration and detailing deficiencies are present. The anchorage of the internal steel reinforcement can be critical under particular confinement conditions of external pressure, concrete cover and transverse reinforcement. The interaction between different confinement contributions and their effects on bond were investigated with a novel experimental set-up that removed the parasitic support pressure. With significant transverse reinforcement and varying concrete cover, maximum bond strengths were obtained for intermediate cover-to-diameter ratios. The transverse reinforcement contribution depended on the occurrence of splitting cracks. These findings can lead to improved assessment and maintenance strategies.

Isotropic pressure-induced electronic band structure of BaTiO3, SrTiO3 and CaTiO3 with its impact on structural and optical properties: ab-initio calculation

ABSTRACT The present theoretical study offers a comprehensive investigation under the application of systematic external static isotropic pressure, phase stability, electronic-band structure and their impact on the optical characteristics of BaTiO3, SrTiO3 and CaTiO3. All the computational works were performed by Cambridge Serial Total Energy Package, using generalised gradient approximation and density functional theory, Perdue-Burke-Ernzerhof, along with the ultra-soft pseudo-potential for the frozen core. According to structural properties, there is no phase transformation and the structure of all compounds remains cubic. The band structure is a perfect tool to observe the nature of a material, such as an insulator, semiconductor or metal. When the pressure is applied, the band gap of BaTiO3, SrTiO3 and CaTiO3 increases and retains their indirect nature. The total/partial/elemental density of states has been estimated for the full description of the band structure. To verify the authenticity of BaTiO3, SrTiO3 and CaTiO3, various optical parameters have been reported such as the real dielectric functions, imaginary dielectric functions, absorption, refractive index, extinction coefficient, energy loss function and reflectivity. All discrepancies in structural parameters, band structure and optical properties occurred due to applied pressure, and BaTiO3, SrTiO3, and CaTiO3 are connected .

First-principles calculations to investigate band gap of cubic BaThO3 with systematic isotropic external static pressure and its impact on structural, elastic, mechanical, anisotropic, electronic and optical properties

The motive of this study is to offer a comprehensive evaluation of the structural, elastic, mechanical, anisotropic, electrical and optical characteristics of BaThO3 under the pressure range of 0 GPa–113 GPa. There is no phase transformation and the structure remains cubic but a diminishment in lattice parameters is observed. The material is found to be mechanically stable, inflexible, rigid and has high resistance to shear stress by computing the various elastic and mechanical (bulk modulus, shear modulus and young's modulus) parameters. The Pugh/Frantsevich ratios, Cauchy pressure, Poisson's ratio, and the Kleinman's parameter have proved the ductility, metallic bond nature and high-pressure endurance of the material. Distinctive anisotropy factors are engaged to verify that a compound is anisotropic. When the electronic band structure (BS) is taken into consideration, a change from wide band gap semiconductor (3.174eV) to narrow band gap semiconductor (1.832eV) and eventually metal (0eV) is seen. The total density of states (TDOS), the partial density of states (PDOS) and elemental partial density of states (EPDOS) have all been estimated in order to investigate the electronic BS. To enforce the relevance of this material, the real ε1(ω) and imaginary ε2(ω) dielectric functions, absorption I(ω), refractive index n(ω), extinction coefficient k(ω), loss function L(ω), reflectivity R(ω) and real/imaginary conductivity have all been calculated. The static values of ε1(ω) and n(ω) increase with applied pressure. Since its absorption spectra are present in the UV range, this is the best material to utilize as a UV filter. Additionally, its high refractive index, absorption, reflectivity, and conductivity make it an excellent component in optoelectronic devices.

Numerical Simulation of Stresses in Functionally Graded HCS-MgO Cylinder Using Iterative Technique and Finite Element Method.

In this study, a thick hollow axisymmetric functionally graded (FG) cylinder is investigated for steady-state elastic stresses using an iteration technique and the finite element method. Here, we have considered a functionally graded cylinder tailored with the material property, namely, Young’s modulus, varying in an exponential form from the inner to outer radius of the cylinder. A mathematical formulation for stress analysis of functionally graded cylinder under internal and external pressure conditions is developed using constitutive relations for stress–strain, strain–displacement relations and the equation of equilibrium. The effect of the in-homogeneity parameter on radial displacement, radial and tangential stresses in a functionally graded cylinder made up of a High Carbon Steel (HCS) metal matrix, reinforced with Magnesium Oxide (MgO) ceramic is analyzed. The iterative method implemented is fast and converges to the solution which can be further improved by considering a higher number of iterations. This is depicted graphically by using radial displacement and stresses in a pressurized functionally graded cylinder obtained for the first two iterations. An iterative solution for non-FGM (or homogeneous material) is validated using the finite element method. The mechanical responses of the functionally graded cylinder obtained from the iterative method and the finite element method are then compared and found to be in good agreement. Results are presented in graphical and tabular form along with their interpretations.

First-principles calculations to investigate variation in the bandgap of NaSrF3 Fluoro-Perovskite with external static isotropic pressure and its Impact on optical properties

The theoretical investigation of NaSrF3 fluoro-perovskite is carried out using ultra-soft pseudo-potential USP plane wave and Perdew Burke Ernzerhof (PBE) exchange–correlation functional of Generalized Gradient Approximation (GGA) with the help of the density functional theory-based Cambridge Serial Total Energy Package (CASTEP) code. All the properties are investigated under the effect of external static isotropic pressure ranging from 0 to 100 GPa and 300 GPa. The lattice parameters of the material are decreased with the increment of the external pressure. The value of band gap is found 4.328, 2.795, and 0 eV at 0, 100 and 300 GPa, respectively. The optical properties of the material i.e., absorption, reflectivity, dielectric function, refractive index, conductivity, and loss function are also investigated. The static values of ε1 (ω) and n (ω) increase with the increase in pressure. It is resulted from the optical properties that the material has a high refractive index, absorption, and conductivity, and thus it is applicable in different photovoltaic systems like data storage media, and photonic crystals. Furthermore, the electronic properties of the material indicate that it operates as a semiconductor at 0 to 100 GPa while it acts as a conductor at 300 GPa.

Anisotropic acousto-optic interaction in a KRS-5 crystal.

We investigated the acoustic and acousto-optic parameters of cubic crystal KRS-5, which can be used in acousto-optic devices operating with optical radiation from visible to far infrared regions. The results of acoustic and acousto-optic property calculations are presented. Also, we present a possibility of obtaining optical birefringence in cubic material when external static pressure is applied to the KRS-5 crystal. We discuss in detail the results of anisotropic Bragg diffraction observation in cubic crystal in the presence of external static pressure.

First-principles calculations to investigate ultra-wide bandgap semiconductor behavior of NaMgF3 fluoro-perovskite with external static isotropic pressure and its impact on optical properties

The structural, electronic, and optical properties of cubic fluoro-perovskite NaMgF3 were investigated theoretically at pressures ranging from 0 to 100 GPa with a 10-step escalation, i.e., 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100 GPa. The research is conducted by using density functional theory (DFT) based CASTEP (Cambridge Serial Total Energy Package) code with ultra-soft pseudo-potential USP plane wave and Perdew Burke Ernzerhof (PBE) exchange-correlation functional of Generalized Gradient Approximation (GGA). The band gap is found to be increasing from 5.749 to 8.723 eV when the pressure is increased from 0 to 100 GPa. The nature of the band gap remained indirect whether the pressure was applied or not. A significant increment was found in the band gap till 40 GPa as compared to higher pressure. Under the effect of pressures ranging from 0 to 100 GPa, several optical properties like the refractive index, loss function, reflectivity, and absorption coefficient have also been determined. The main peaks of dielectric function (real and imaginary), reflectivity, loss function, and refractive index (n) are observed to move towards higher values of energy with increasing pressure. A material that has a high optical conductivity, absorption, and refractive index is ideal for photovoltaic applications. Other optical technologies that use such material include waveguides, data storage medium, and photonic crystals.

The electric vehicle and renewable energy: Changes in boundary conditions that enhance business model innovations

Business model innovation consists of new ways of defining, creating, and capturing value including non-monetary value, and is an indicator of crossing traditional sector boundaries, thereby providing the necessary agency to achieve significant new market opportunities around technological innovation. Individual businesses may lack the scope or depth of competencies required, especially in the case of entrenched industrial structures, framings, regulatory provision, and consumer attitudes. Business models are thus potentially ossified within highly structured socio-technical systems. This article analyses innovation in business models arising from the confluence of two mature and stable industries under conditions of external pressure, deregulation, privatisation, and the emergence of a new, shared interest. We illustrate the paper with examples of vehicle manufacturers developing business concepts for vehicle-to-grid, domestic energy, second life, and industrial electricity provision from renewable energy. We find that in the period 2012 to 2020, 17 vehicle manufacturers used 38 electric models to test a diverse menu of options established from four applications with changes in boundary conditions that have influenced business model innovation. This process created space for energy policy and mobility policy to become increasingly intertwined as battery electric vehicles enter the mass market, raising questions over the future of automobility as well as electricity generation and distribution.

Research on models for estimating aerodynamic and energy consumption performance of fan filter units (FFUs)

Fan filter units have been widely applied in various cleanrooms and consumed massive energy and operation cost. A large number of tests were required for evaluating the aerodynamic performance of FFUs. On the other hand, the performance of FFUs would be changed during their service life and they may not work at energy efficient points. However, there was no method estimating the aerodynamic and energy consumption performance for FFUs to reduce unnecessary tests and help adjusting FFUs to work at energy efficient points. In the current research work, models for estimating the aerodynamic and energy consumption performance of FFUs were built by adopting the fan similarity law, which can be used to predict parameters including the airflow rate, input power, static pressure aerodynamic efficiency and energy performance index for FFUs at different rotation speeds and working points based on certain tested parameters. Laboratory tests for four FFUs were conducted to validate built models. The biases of estimated parameters from tested parameters were detailed. Results show that built models were able to estimate accurately the parameters of FFUs at different rotation speeds and with different filters with deviations lower than 5%. According to the analysis for estimation biases, it was suggested to conduct the estimation using built models under certain conditions to reduce deviations, including choosing parameters at the max rotation speed as known values, estimating parameters at working points with rotation speed greater than 70% of the max speed and external static pressure between 50 Pa and 150 Pa.

Asymmetry between Accretional Advance and Erosional Retreat of Shoreline Position in On-offshore Direction

Yoo, H.J.; Kim, H.; Lee, J.L., and Park, J.Y., 2021. Asymmetry between accretional advance and erosional retreat of shoreline position in on-offshore direction. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 6–10. Coconut Creek (Florida), ISSN 0749-0208. Episodic shoreline retreat often slowed recovery in low frequency periods (weeks or months). The asymmetry between wave energy rise and collapse is closely related to the asymmetry of shoreline advancement and retreat, but the latter is more pronounced due to the different profile adjustment processes. Long-term wave time series data and shoreline time series data were analyzed at Won-pyeong beach located on the east coast of Korea. When waves such as storms come into the beach, the shoreline quickly retreated, and in relatively quiet times, the beach slowly recovered to it's original position. Also, the asymmetry of the shoreline position with respect to time is stronger than that of the wave height. A methodology is proposed here, and the envelope rope curve can be used to predict profile and average shoreline changes in the reference section for erosion steps such as storms.The proposed equation was in good agreement for shoreline asymmetry position, and is satisfactory. Empirical formular are slightly different in the relatively calm period, this is an artificial change formed by external pressure conditions such as artificial nourishment. Several variables were used as correction factors. It`s important for future research to propose standardized correction factors and ranges by applying them at various sites.

Effect of inlet duct design on fan performance and static pressure measurements of indoor air handling units (ASHRAE RP-1743)

Increasing energy efficiency requirements lead to substantial increases in residential air handler unit’s length, in turn preventing usage of requiring inlet ductwork for rating tests due to testing facilities space constraints. Therefore, the main goal of ASHRAE Research Project 1743 was to investigate reduced-length alternative inlet duct configurations as compared to ASHRAE Standard inlet duct in terms of fan performance. Additionally, the project investigated other effects that might affect the repeatability of equipment testing. The investigated effects were hysteresis effect associating with adjusting external static pressure through unit under test, atmospheric pressure effect associating with daily fluctuations of atmospheric pressure in a location, side flow effect from a destratification fan in the testing facility, and floor distance effect on ASHRAE Standard 37 inlet duct. The reduced-length alternative inlet duct configurations considered were 4-inch inlet duct, inlet box with and without guide vanes, and nonconventional reduced alternative inlet duct. The alternative inlet duct configurations maintained fan performance within ±5% for fan power and ±2.5% for air volumetric flowrate except for the inlet box without guide vanes. The reduction in length relative to the standard inlet duct was between 38% and 44% for the inlet box configuration up to 71% and 73% for the reduced alternative inlet duct configuration. The hysteresis effect was significant for the push-through electronically-commutated-motor fan unit and was noticeable for the pull-through constant-torque-motor fan unit at a low air flowrate. Atmospheric pressure affected only the electronically-commutated-motor fan units significantly. Side flow from external ‘destratification’-fans had a significant effect on the push-through units in some of the configurations. Floor distance had an insignificant effect on fan performance during testing the standard inlet duct.

Experimental investigation on backflow of power-law fluids in planar fractures

In hydrofracturing, we model the backflow of a non-Newtonian fluid in a single flat-walled fracture of planar geometry and support our conceptualization with laboratory experiments. We consider a power-law fluid, a spatially homogeneous fracture aperture, and its variation in time depending on the internal fluid pressure and the elastic relaxation of the walls. The relationship between the latter quantities may be linear, akin to a Winkler soil, or nonlinear, due to the progressive softening or stiffening of the boundary associated with the properties of the surrounding rock. The result is an integrodifferential problem that generally admits a closed-form solution, albeit implicit for some quantities. In particular, a comparison is conducted between the drainage time in the present configuration and point drainage in radial geometry. The approach is generalized by introducing a leak-off, i.e., a loss of fluid at the fracture boundaries that accelerates the fracture closure, when compared to the no leak-off case. To validate the theoretical results, 14 experiments are conducted with an ad hoc replica of a rectangular fracture of aspect ratio 2.5–2.7, with a maximum height of ≈2 mm; the elastic reaction of the walls is due to o-rings, also sealing the fracture without adding friction disturbances. Fluids with different rheology, both Newtonian and shear-thinning, are associated with different boundary conditions of external pressure and overload. The match between theory and experiments is fairly good, with discrepancies of a few percent essentially due to the approximations of the theoretical model, and, for shear-thinning fluids, to the simplified constitutive equation.

Beneficiaries or Charity: The Influence of the Source of Acknowledgments.

This study employs entitativity theory to explore how acknowledgment letters from various thankers (e.g., a group of beneficiaries, a charity) influence donors’ subsequent donation desires. This empirical research consists of three experiments. Study 1 reveals that an acknowledgment letter from a group of beneficiaries elicits more favorable subsequent donation desires than an acknowledgment letter from a charity. To shed light on the psychological mechanism underlying this effect, Study 2 shows that a categorical appellation can enhance the effects of an acknowledgment letter sent by a charity. Study 3 reveals that the influence of the thanker is stronger under no external pressure conditions (than under external pressure). The current study offers insightful suggestions for the management and administration of charities.