Critical Parameters and Critical-Region ($$p,\rho,T)$$ Data of trans-1,1,1,3-Tetrafluorobut-2-ene [HFO-1354mzy(E)]

This study presents the experimental measurement of the \(p\rho T\) properties and critical parameters of a low GWP type refrigerant, trans-1,1,1,3-Tetrafluorobut-2-ene (HFO-1354mzy(E)). The sample purity of the substance was 99 area %. \(p \rho T\) property measurements and visual observations of the meniscus of HFO-1354mzy(E) were carried out using a metal-bellows volumometer with an optical cell. The critical temperature was determined by observation of the critical opalescence. The critical pressure and critical density were determined as the inflection point of the isothermal \(p \rho T\) property data at the critical temperature. For more precise clarification of the thermodynamic surface in the vicinity of the critical point, additional \(p \rho T\) property measurements were carried out on three isotherms in the supercritical region. The expanded uncertainties (\(k = 2\)) in the temperature, pressure, and density measurements were estimated to be less than 3 mK, 1.2 kPa, and 0.32 \(\hbox {kg} \cdot \hbox {m}^{-3}\), respectively. The expanded uncertainties of the critical parameters were estimated to be less than 13 mK, 1.4 kPa, and 2.3 \(\hbox {kg} \cdot \hbox {m}^{-3}\), respectively. These values are the first reported for HFO-1354mzy(E) and are necessary for the development of its equation of state in the near future.     

Structural optimization under uncertain loads and nodal locations

This paper presents algorithms for solving structural topology optimization problems with uncertainty in the magnitude and location of the applied loads and with small uncertainty in the location of the structural nodes. The second type of uncertainty would typically arise from fabrication errors where the tolerances for the node locations are small in relation to the length scale of the structural elements. We first review the discrete form of the uncertain loads problem, which has been previously solved using a weighted average of multiple load patterns. With minor modifications, we extend this solution to include loads described by continuous joint probability density functions. We then proceed to the main contribution of this paper: structural optimization under uncertainty in the nodal locations. This optimization problem is computationally difficult because it involves variations of the inverse of the structural stiffness matrix. It is shown, however, that for small uncertainties the problem can be recast into a simpler but equivalent structural optimization problem with equivalent uncertain loads. By expressing these equivalent loads in terms of continuous random variables, we are able to make use of the extended form of the uncertain loads problem presented in the first part of this paper. The optimization algorithms are developed in the context of minimum compliance (maximum stiffness) design. Simple examples are presented. The results demonstrate that load and nodal uncertainties can have dramatic impact on optimal design. For structures containing thin substructures under axial loads, it is shown that these uncertainties (a) are of first-order significance, influencing the linear elastic response quantities, and (b) can affect designs by avoiding unrealistically optimistic and potentially unstable structures. The additional computational cost associated with the uncertainties scales linearly with the number of uncertainties and is insignificant compared to the cost associated with solving the deterministic structural optimization problem.     

Numerical study on compression processes of cohesive bimodal particles and their packing structure

In this study, the compression characteristics of bimodal cohesive particles were investigated using a discrete element method (DEM) simulation. The compression and packing processes were simulated under different conditions of size ratios of 1–4 and fine particle mixing ratios of 0–0.5. The cohesive force was expressed using the surface energy proposed by the Johnson-Kendall-Roberts (JKR) cohesion model having a surface energy of 0–0.2 J/m². The calculated results demonstrated that even in the case of cohesive particles, an increase in the particle size ratio reduced the void fraction of the powder bed during the packing and compression processes. In addition, it was found that the cohesive force decreased the contact number, especially the coarse-coarse contacts, although it had little impact on the void fraction. Our DEM simulations suggested that it is necessary to evaluate the contact numbers even under similar void fractions, which will be essential in the case of different material mixtures, such as all-solid-state batteries.     

Synthesis of organic–inorganic polymer hybrids from poly(vinyl chloride) and polyhedral oligomeric silsesquioxane via CH/π interaction

The synthesis of poly(vinyl chloride) (PVC)/polyhedral oligomeric silsesquioxane (POSS) polymer hybrids was performed utilizing CH/π interaction. Poly(vinyl chloride) as an organic component was dissolved in THF with octaphenethylsilsesquioxane (Phenethyl-POSS) or octacyclohexylsilsesquioxane (Cyclohexyl-POSS) as an inorganic component. The resulting mixture was placed at 40 °C for 2 weeks. The obtained polymer hybrid was dried in vacuo at 60 °C for 2 days. The transparent polymer hybrids were obtained when Phenethyl-POSS was employed as an inorganic component. In contrast, polymer hybrid became turbid when Cyclohexyl-POSS was used. These results suggest that the CH/π interaction was found to act as an important role for the dispersion of Phenethyl-POSS in the PVC matrix.     

Characterization of coke deposited on catalysts by carbon K-edge near edge X-ray absorption fine structure (NEXAFS) spectroscopy

C K-edge NEXAFS spectra could distinguish between the structures of coke on the catalysts used in fluid catalytic cracking, hydrotreatment and dry reforming of methane from the characteristic ;π^* features. A particular advantage of NEXAFS spectroscopy was found in the characterization of highly aromatic coke that could not be analyzed by cross-polarization ¹³C-NMR due to the lack of magnetization transfer from ¹H to ¹³C. The NEXAFS results elucidated two different structures of coke on Ni catalysts used in dry reforming of methane; one with a graphitic structure formed at lower temperatures and the other with a non-graphitic structure formed at higher temperatures. This revised version was published online in June 2006 with corrections to the Cover Date.     

Transient analysis of stress waves around two rectangular cracks under impact load

The three-dimensional response of two rectangular cracks in an infinite elastic medium to impact load is investigated in this paper. Fourier and Laplace transforms are applied and the problem is reduced to that of solving dual integral equations in the Laplace transform domain. To solve these equations, the crack surface displacement is expanded in a double series of functions which are zero outside of the cracks. The unknown coefficients accompanied in that series are solved with the aid of the Schmidt method. The dynamic stress intensity factors are computed numerically.     

Dynamic stresses around two cracks placed symmetrically to a large crack

Dynamic stresses around three cracks in an infinite elastic plate have been solved. Two cracks, which are small and equal, are situated ahead of a large crack so as to allow for geometrical symmetry. Time-harmonic normal traction acts on each surface of these cracks. To solve the problem, two solutions are combined. One of them is a solution for a crack in an infinite plate and another is that for two collinear cracks in an infinite plate. The Schmidt method is used to satisfy the boundary conditions on the cracks' surfaces with use of the combined solutions. Stress intensity factors are calculated numerically for some of these crack configurations.     

Suppression of Noble Metal Sintering Based on the Support Anchoring Effect and its Application in Automotive Three-Way Catalysis

Suppression of noble metal sintering is a very important approach in the development of automotive three-way catalysts. The investigation into the Pt sintering behavior revealed that the formed Pt–O–M (M: cation of oxide, i.e., cerium oxide) bond acted as an anchor to suppress the Pt sintering, and that the strength of the Pt-oxide-support interaction was well correlated with the electron density of oxygen in the support oxide. To achieve a good balance between catalytic activity and the sintering suppression, ceria based oxide support was verified to be suitable for Pt, and zirconia based oxide support was appropriate support for Rh. Through optimizing the configuration of Pt and Rh in the catalyst, a novel three-way catalyst was developed successfully, and this catalytic activity is far superior to the conventional catalyst, but with lower noble metal content.