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We report the observation of local structural dipoles that emerge from an undistorted ground state on warming, in contrast to conventional structural phase transitions in which distortions emerge on cooling. Using experimental and theoretical probes of the local structure, we demonstrate this behavior in binary lead chalcogenides, which were believed to adopt the ideal, undistorted rock-salt structure at all temperatures. The behavior is consistent with a simple thermodynamic model in which the emerging dipoles are stabilized in the disordered state at high temperature due to the extra configurational entropy despite the fact that the undistorted structure has lower internal energy. Our findings shed light on the anomalous electronic and thermoelectric properties of the lead chalcogenides. Similar searches may show that the phenomenon is more widespread.

Shakhmatkin and Vedishcheva thermodynamic model (SV TDM) of the 45S5 Bioglass® doped with three different amounts of Li 2 O (4.1, 9.9, and 12.3 mol%) was evaluated at T = 800 K. The 55 components of SV TDM were considered, among them 12 lithium containing compounds. Different number of components with not negligible equilibrium molar amount was found for different glass compositions (9 or 10). In all glass compositions containing nonzero amount of Li 2 O, the four lithium compounds with not negligible equilibrium amount were identified, i.e., Li 2 O·SiO 2 , 3Li 2 O·P 2 O 5 , Li 2 O·2CaO·2SiO 2 , and 2Li 2 O·SiO 2 . In the 45S5 glass composition four phosphate compounds with not negligible abundance were identified: 9Na 2 O·6SiO 2 ·2P 2 O 5 , Na 2 O·2CaO·P 2 O 5 , 5Na 2 O·4SiO 2 ·P 2 O 5 , and Na 2 O·CaO·P 2 O 5 . In all other glasses the 3Li 2 O.P 2 O 5 was found with not negligible abundance. Moreover, in the glass with 4.1 mol% Li 2 O the Na 2 O·2CaO·P 2 O 5 and 3Li 2 O·P 2 O 5 compounds were found with not negligible abundance. For each studied glass the glass transition temperature, coefficient of thermal expansion of glass and metastable melt were measured by thermodilatometry. The low temperature viscosity was measured by thermomechanical analysis. The viscous flow activation energy was evaluated from the viscosity temperature dependence. The compositional dependence of measured thermal properties was analyzed by correlation analysis with the Q-distribution of silicate and phosphate units.

High demands for precision laser soldering technologies arise as digital devices move towards volume downsizing. Laser soldering is a very complicated thermodynamic chemical process, and controlling the temperature also becomes challenging. Based on experimental data, a thermodynamic model for the soldering process is developed in this study, taking into account variables like laser power, spot size, and heating duration, among others. A novel feedforward-PI control algorithm is proposed using the model which includes a target temperature curve-based feedforward algorithm to help the PI feedback control to achieve precise temperature control during the laser soldering process. Experiments and comparisons are used to demonstrate the efficacy of the suggested model and control approach. The outcomes show that the suggested model is capable of effectively describing the dynamics of laser soldering. The temperature standard deviation of the proposed control technique is shown to be lower than 55%-60% of the classic PID control approach, while the former has higher precision.

Shakhmatkin and Vedishcheva thermodynamic model (SV TDM) of 45S5 bioglass was evaluated at T  = 800 K. From 42 considered system components, only 7 components (Na 2 O⋅SiO 2 , Na 2 O⋅3CaO⋅6SiO 2 , 3CaO⋅2SiO 2 , CaO⋅SiO 2 , 9Na 2 O⋅6SiO 2 ⋅2P 2 O 5 , 2CaO⋅SiO 2 , and Na 2 O⋅2CaO⋅P 2 O 5 ) were present in significant equilibrium molar amount. The calculated Q-distribution of silicate units (22.6% of Q 3 , 63.1% of Q 2 , 10.1% of Q 1 , and 4.2% of Q 0 ) was compared with the Q-distribution for so-called crystalline reference state (6.3% of Q 3 , 93.7% of Q 2 ). Further, both Q -distributions were compared with the MAS NMR experimental data published by different authors (e.g. 33.3% of Q 3 , 54.5% of Q 2 , and 12.2% of Q 1 , or 17.8% of Q 3 , 76.7% of Q 2 , and 5.5% of Q 1 ). It was concluded that there is no principal difference between SV TDM and MAS NMR distributions of silicate units. Further the Q -distribution of phosphate units was analysed. The CRS resulted in 100% presence of Q 0 units (i.e. PO 4 3− ). The SV TDM resulted in significantly broader distribution, i.e. 4.5% of Q 2 , 10.4% of Q 1 , and 85.1% of Q 0 . This distribution is comparable with those obtained by MAS NMR (e.g. 26.7% of Q 1 and 73.3% of Q 0 ).

The demand for man-made cellulosic fibres is expected to grow in the future. One commercially-available concept to supply fibres is Lyocell manufacturing from dissolving wood pulps using N-Methylmorpholine N-oxide (NMMO) as the solvent. The literature qualitatively indicates that NMMO recycling efficiency is a key factor for profitable operation. Process design information and parameter data are however poorly available publicly to illustrate the cost factors. Therefore, systematic techno-economic analysis of a 50 kt/year Lyocell plant was conducted using steady-state process simulation and cost modeling. With the simulation models, the underlying technical process design and modelling decisions, and economic assumptions were studied. NMMO makeup need is an important cost item. The simulated makeup need is very dependent on the design of the solvent recovery system and the vapor-liquid equilibrium thermodynamic model selection. On the other hand, water use, fibre washing process design, and washing model parameterization have relatively lower impact on the cost of production. Raw material cost and capital expenses are most critical cost items when the NMMO recycling efficiency is high.

This work extends the thermodynamic model of associated solutions used in the past to describe the structure and properties of glasses to the area of complex multicomponent glasses with polyvalent elements, where it has not been applied until now either due to the absence of Gibbs energies of formation of the necessary compounds or due to oxidation–reduction equilibrium in the presence of a gas phase containing oxygen. While the fitting of unknown Gibbs energies based on experimental data has already been applied to some extent in our previous work, the implementation of redox is, to the best of our knowledge, new. Four concentration series were taken from the published data from the glass-forming ternary system CaO–MoO 3 −P 2 O 5 : A) xMoO 3 −(0.5–0.75x)CaO−(0.5–0.25x)P 2 O 5 ; B) xMoO 3 −(0.5–0.875x)CaO−(0.5–0.125x)P 2 O 5 ; C) xMoO 3 −(0.5−x)CaO−0.5P 2 O 5 ; M) xMoO 3 −(1−x)P 2 O, for which the distributions of Q n units were also published (Q denotes the PO 4 tetrahedral unit with n bridging oxygens) by the 31 P MAS NMR method and the Mo [V] /ΣMo fraction by the ESR method [Černošek et al. (J Solid State Chem 303:122522, 2021); Holubová et al., (J Non-Cryst Solids 607:122222, 2023)]. The following compounds were considered in the TD model: P 2 O 5 , CaO, Mo [VI] O 3 , Ca(PO 3 ) 2 , Ca 2 P 2 O 7 , (Mo [VI] O 2 )(PO 3 ) 2 , (Mo [VI] O 2 ) 2 (P 2 O 7 ), (Mo [VI] O 2 ) 3 (PO 4 ) 2 , (Mo [V] O) 2 (PO 3 ) 2 (P 2 O 7 ), (Mo [V] O)PO 4 . All except the hypothetical compound (Mo [VI] O 2 ) 3 (PO 4 ) 2 exist, and their structure is known. Binary phosphate compounds with molybdenum lack Gibbs energies of formation. Therefore, one of the series, namely A, was used to determine these energies by nonlinear regression with the help of a genetic algorithm, without/with redox, and then the distribution of Q n units and the fraction of Mo [V] /ΣMo was predicted for the remaining series. It was found that the distribution of Q n units can be described by the TD model with redox only. During the reduction of molybdenum, the distribution of Q n unit’s changes, and thus also the connectivity of the phosphate network, for example, according to the reactions: (MoO 2 ) 2 (P 2 O 7 )—> 2(MoO)PO 4  + 1/2O 2 , in which Q 1 —> Q 0 and 2(MoO 2 )(PO 3 ) 2 —> (MoO) 2 (PO 3 ) 2 (P 2 O 7 ) + 1/2O 2 in which Q 2 —> Q 1 . Despite the fact that the TD model with redox gives excellent agreement in the case of the Q n distribution, the agreement with the ESR measurements of the Mo [V] /ΣMo ratio is not good. The TD model predicts significantly more pentavalent molybdenum in the glass.

At present, the main purpose of gas turbine fault prediction is to predict the performance decline trend of the whole system, but the quantitative and thorough performance health index (PHI) research of every major component is lacking. Regarding the issue above, a long-short term memory and gas path analysis (GPA) based gas turbine fault diagnosis and prognosis method is proposed, which realizes the coupling of fault diagnosis and prognosis process. The measurable gas path parameters (GPPs) and the health parameters (HP) of every main component of the goal engine are obtained through the adaptive modeling strategy and the gas path diagnosis method based on the thermodynamic model. The predictive model of the Long-Short Term Memory (LSTM) network combines the measurable GPPs and the diagnostic HPs to predict the HPs of each major component in the future. Simulation experiments show that the proposed method can effectively diagnose and predict detailed, quantified, and accurate PHIs of the main components. Among them, the maximum root mean square error (RMSE) of the diagnosed component HPs do not exceed 0.193%. The RMSE of the best prediction model is 0.232%, 0.029%, 0.069%, and 0.043% in the HP prediction results of each component, respectively.

In this study, behaviors of metals and their effects on phosphorus recovery by calcium phosphate were investigated by the laboratory and pilot experiments as well as by the modified thermodynamic model. Batch experimental results indicated that the efficiency of phosphorus recovery decreased with the increase in metal content and more than 80% phosphorus can be recovered with a Ca/P molar ratio of 3.0 and a pH of 9.0 for the supernatant of an anaerobic tank in the A/O process with the influent containing a high metal level. The mixture of amorphous calcium phosphate (ACP) and dicalcium phosphate dihydrate (DCPD) was assumed to be the precipitated product with an experimental time of 30 min. A modified thermodynamic model was developed using ACP and DCPD as the precipitated products, and the correction equations were incorporated to simulate the short-term precipitation of calcium phosphate based on the experimental results. From the perspective of maximizing both the efficiency of phosphorus recovery and the quality or purity of the recovered product, the simulation results showed that a pH of 9.0 and a Ca/P molar ratio of 3.0 were the optimized operational condition for phosphorus recovery by calcium phosphate when the influent metal content was at the level of actual municipal sewage.

The conventional Zel’dovich-von Neumann-Döring (ZND) detonation theory is modified with two-dimensional velocity vectors to account for the performance and steady-state flow features of a rotating detonation engine. The developed analytical model explains many of the steady-state features of the rotating detonation and its thermodynamics. The generation of swirl is shown to be the primary mechanism of energy transfer.

Mathematical modeling is the most important tool for constructing the theory of concentrated tornado-like vortices. A review and analysis of computational and theoretical works devoted to the study of the generation and dynamics of air tornado-like vortices has been conducted. Models with various levels of complexity are considered: a simple analytical model based on the Bernoulli equation, an analytical model based on the vorticity equation, a new class of analytical solutions of the Navier–Stokes equations for a wide class of vortex flows, and thermodynamic models. The approaches developed to date for the numerical simulation of tornado-like vortices are described and analyzed. Considerable attention is paid to developed approaches that take into account the two-phase nature of tornadoes. The final part is devoted to the analysis of modern ideas about the tornado, concerning its structure and dynamics (up to the breakup) and the conditions for its occurrence (tornadogenesis). Mathematical modeling data are necessary for interpreting the available field measurements while also serving as the basis for planning the physical modeling of tornado-like vortices in the laboratory.