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Designing alternative fuels for advanced compression ignition engines necessitates a predictive model for cetane number (CN). In this study, the physics-informed graph neural networks are introduced for a reliable CN prediction by considering molecular features pertinent to the physical properties of molecules that affect CN. The reliability of measured data is another key factor to consider for improving the predictive model. Various experimental instruments for measuring CN exist, including standard and non-standard methods. In this regard, a systematic data quality analysis was carried out for the total 630 CNs collected from literature and new measurements in this study using Advanced Fuel Ignition Delay Analyzer (AFIDA). The results from this data curation process were reflected in the model by imposing lower sample weights on the data coming from less reliable measurement techniques. This approach effectively maximized the prediction accuracy while incorporating data from all available sources. Using the sample weights decreased the mean absolute error (MAE) up to 0.8 CN units. The accuracy was also improved by introducing the CN-related physical properties (the number of hydrogen bond donors and acceptors); the test set MAE is 5.74 and 7.01 for the model with and without such properties, respectively. Investigating molecular structural effects on CN was also carried out to gain chemical insights into factors used to design new fuel candidates. The dimensionality reduction analysis of feature vectors showed a clear clustering in terms of functional groups and CN and the structural effect derived from the model was consistent with the physicochemical insights. This physics-informed model and data curation would be helpful for accurate CN prediction and inform rational fuel design. [ABSTRACT FROM AUTHOR]

The high ϕ -sensitivity (η) of ignition delay time (τ IDT) is one of the desirable fuel properties for the high-load extension of advanced compression ignition engine. Recent studies revealed the effectiveness of a high dilution rate (x D) for enhancing η at the engine-relevant conditions. This study aims to quantify the effect of dilution on the η of isooctane using a combined experiment-simulation approach. The ignition delay of the isooctane/air mixture was measured with an Advanced Fuel Ignition Delay Analyzer (AFIDA) over the temperature range of 623 – 923 K at 10 bar pressure with global ϕ = 0.3 – 0.6, with and without 28.6% of additional N 2 dilution. For precise evaluation of experimental η , the facility effect of the AFIDA experiment was characterized with three-dimensional computational fluid dynamics (3-D CFD) simulation. The temperature in the combustion chamber from 3-D CFD indicated a substantial temporal dependency, varying up to ∼52 K by charge-cooling of fuel injection and heat transfer from the wall. We introduced the dimensionless number θ(t) for characterizing the temporal profile of chamber temperature. Consideration of the facility effect using θ(t) resulted in better agreement between the experimental η and zero-dimensional (0-D) kinetics simulation. The refined η were then further utilized to quantify the effectiveness of dilution to η. The extent of η enhancement with dilution strategy was maximized at the low-temperature chemistry regime, increasing η by 77% with a 28.6% dilution rate. Further analysis on the dilution effect was carried out using 0-D kinetics simulation, revealing the critical dimensionless numbers relevant to the effectiveness of dilution to η enhancement. This study is the first experiment-simulation combined research to quantify the effect of dilution on η , facilitating the kinetics model refinement for better reproduction of ϕ -sensitivity. [ABSTRACT FROM AUTHOR]

• A chemical tanker port call policy direction has been suggested. • A novel port call optimization model has been designed by reflecting the suggested policy direction. • Computational techniques have been suggested can solve large-scale problems. • The technical suitability and effectiveness of the proposed method have been verified. We study a novel chemical tanker port call optimization framework to improve the efficiency of waterway traffic control, in which chemical tankers load and unload cargoes while visiting multiple terminals. We formulate this problem as a mixed-integer program to minimize the total cost of vessel operations while compressing the schedule of cargo operations. The port call optimization framework integrates decentralized scheduling efforts by different stakeholders to minimize the traffic congestion satisfying policy, operational, and technical requirements, while embracing the current competitive scheduling discipline. Solving real-world problems can be computationally challenging. Hence we propose efficient solution techniques to promote fast convergence to optimum solutions. As we compare the vessel operational schedule from the proposed port call optimization model with monthly transit data in the past, terminal utilization is improved by more than 250% and the number of individual tanker's transit is reduced by 28%. Suggested computational techniques ensured the solving of real-world problems in approximately 10 minutes. [ABSTRACT FROM AUTHOR]

This study explored the prediction of the effect of dilution on the ignition delay of syngas and hydrocarbon fuels from dimensionless parameters. In this regard, the dilution effect was categorized into two sub-effects. The first is a non-chemical effect, which mainly represents the effect of decreasing the fuel-air concentration and the effect of heat-release damping. The second is the chemical effect induced by participation of the diluent in the reaction pathway. Then, we derived the determining parameters of each sub-effect based on chemical kinetics. The non-chemical effect was found to be related to the normalized sensitivity of the ignition delay to the total concentration, n ˜ ; the ratio of the molar constant volume specific heat of the diluent and the fuel-air mixture, c v , D * ; and the average Zel'dovich number during the ignition delay, Z ˜ e m , which represents the effect of temperature rise during the ignition delay on the reaction rate. Meanwhile, the extent of the chemical effect was found to be related to the sensitivity of the ignition delay to the reaction rate coefficient of the three-body reactions, S τ 0 − k j , multiplied by the sensitivity of the reaction rate coefficients to the third body concentration, S k j − [ M ] j , and the ratio of the collision efficiency of the diluent and the fuel-air mixture, η D , j *. Based on this relationship, we investigated the correlation between the extent of dilution effect and the aforementioned dimensionless parameters, n ˜ , c v , D * , Z ˜ e m , S τ 0 − k j , S k j − [ M ] j , and η D , j * , under the temperature range of 600–1400 K, pressure of 1–80 bar, and equivalence ratio of 0.5–2 with 13 different syngas or hydrocarbon fuels. Consequently, a strong correlation was found between the dilution effect and the dimensionless parameters, with the deterministic coefficient over 0.95. Furthermore, we suggested a proper form of the empirical correlation for the ignition delay that can cover a wide range of diluent concentrations, considering the extent of the chemical effect appropriately. This study presents the first dimensionless analysis for the dilution effect on ignition delay, developing a general framework for prediction of the effect based on the thermochemical characteristics of a fuel-air mixture. [ABSTRACT FROM AUTHOR]

Resonantly stabilized radicals (RSR's) such as allylic radicals typically have bond energies exceeding 45 kcal/mol and are therefore reasonably long-lived up to quite high temperatures. Consequently, kinetics of the unimolecular dissociations and bimolecular reactions of these long-lived RSR's assume significance in high temperature chemically reacting systems such as in flames. Our recent analyses (J. Cho et al., Proc. Comb. Inst. , 2022) of the uncertainty propagated by the energy transfer parameters for 1-methylallyl (1MA) dissociation to the laminar flame speed, indicates an intricate coupling between the kinetics of 1MA dissociation (chain propagation) and its reaction with H-atoms (chain-termination). This work extends such analyses to other C 3 – C 5 allylic radicals: allyl, 2-methylallyl, 1,1-dimethylallyl, 1,2-dimethylallyl, and 1,3-dimethylallyl. Theoretical kinetics for the C 3 – C 4 allylic radicals were taken from prior literature studies (J.A. Miller et al., J. Phys. Chem. , 2008; J. Cho et al., Proc. Comb. Inst. , 2022; R.S. Tranter et al., Proc. Comb. Inst. , 2017). Potential energy surfaces were newly computed for the dissociations of the larger C 5 allylic radicals and the reactions of these radicals with H-atoms. These PES's were then used to calculate rate constants for the relevant unimolecular and bimolecular reactions. Energy transfer has a crucial role to play in these pressure-dependent reactions and therefore the present kinetics calculations relied on a-priori predictions of collisional energy transfer parameters to best characterize the branching between chain propagating unimolecular dissociations of these allylic radicals and chain terminating bimolecular reactions of these RSR's with H-atoms. Prompt dissociations are now established to be a universal feature of free radical dissociations. Here we have also characterized the propensity for prompt dissociations in these more-stable allylic RSR's and their role in combustion simulations. [ABSTRACT FROM AUTHOR]

Abstract We investigated the effect of inhomogeneous mixing of a fuel–air mixture in a spark-ignition engine on knocking characteristics and the dependency of the effect on the fuel, especially for various ethanol reference fuels with a fixed RON of 100. We assumed that a locally lean spot and rich spots exist in the end gas owing to inhomogeneous mixing and calculated their thermodynamic states with a multizone spark-ignition engine simulation. Subsequently, the ignition delay around the state was measured using a rapid compression machine at varying temperatures and equivalence ratios. The obtained results were processed to calculate ξ , which is the ratio of sound speed to auto-ignition propagation speed, and ϵ , defined as the time required for acoustic front to exit the hot spot divided by the excitation time. Then, we analyzed the knocking occurrence and intensity from the locally lean spot and rich spots based on Zel'dovich and Bradley's ξ – ϵ theory. Our results show that the lean spot has a shorter ignition delay than the stoichiometric mixture (ξ > 0) regardless of the ethanol content, whereas the rich spot does not (ξ < 0), implying that only the lean spot can initiate knocking. This is because the temperature of the lean spot is higher than the surrounding mixture owing to its higher specific heat ratio and less charge cooling effect. In addition, the knocking intensity from the lean spot is found to be maximized with ERF0, showing the largest ξ − 2 value. Further analysis was conducted by dividing ξ into the effect of the temperature gradient, ξ T , and that of the equivalence ratio gradient, ξ ϕ. Consequently, we found that the magnitude of ξ T is related to the activation energy of the fuel, while that of ξ ϕ is determined by the dependency of the pre-heat release characteristics of the fuel on the equivalence ratio. [ABSTRACT FROM AUTHOR]

Highlights • Family firm survival depends on a careful balancing of public and private ownership. • Too much public and too much family ownership both compromise family firm survival. • This inverted-U relationship is stronger when there is a family CEO. • Family firm survival is especially shortened by family ownership from the second generation. Abstract There is a quandary facing many family businesses: namely, that although initially positive for firm survival, beyond a certain level of family ownership, family involvement in ownership and/or management may threaten firm survival, especially under later generation family CEOs. We argue and find in a study of listed Korean firms that a balance between family and public ownership enhances firm survival. Under balanced ownership both types of owners can prevent one another's excesses. Moreover, the negatives of too much family ownership are accentuated when there are family CEOs, particularly in post-founder generations. [ABSTRACT FROM AUTHOR]

We developed a plant model and model-based controller for a heat recovery system with a swirling flow incinerator located in South Korea. First, a plant model was designed to understand the dynamic characteristics of the system. The system was divided into three parts: incinerator, boiler, and steam drum. Then, each part was modeled with a multi-zone, zero-dimensional modeling scheme. Consequently, we found that the plant model followed the dynamic behavior of the target system, particularly for the seven important variables: boiler inlet temperature, superheater inlet temperature, boiler outlet temperature, oxygen mole fraction, steam production rate, steam pressure, and steam temperature. Then, we designed a multi-input multi-output controller for the system with a nonlinear control model. In the controller design, input variables were selected as air flow rate, fuel supply rate and steam valve opening area; while output variables were oxygen mole fraction of exhaust gas, steam production rate and steam pressure. A nonlinear control model was constructed by reducing the plant model. Then a linear quadratic regulator was applied while evaluating control gain at each time step. Finally, we validated the controller on the plant model, which adequately suppressed the disturbance on fuel composition and adjusted the steam production rate. [ABSTRACT FROM AUTHOR]

In this study, the effect of external-exhaust-gas-recirculation (EGR) on anti-knock characteristics of ethanol reference fuels (ERFs) with research octane number (RON) 100 was analyzed by measuring the ignition delay of the simulated end gas from a representative spark ignition (SI) engine operation, i.e. ASTM RON test condition. An in-house SI engine model was used to derive temperature and pressure profiles of the end gas with and without external-EGR for various ERFs, and then the ignition delay was measured by using a rapid compression machine along the derived temperature-pressure paths. The effect of external-EGR on the ignition delay of the simulated end gas was divided into two effects affecting the auto-ignition behavior: composition effect and temperature effect, then each effect was evaluated separately. As a result, the composition effect by adding external-EGR was maximized when the fuel is ERF10. With a regression analysis, it was found that there is the correlation between the amount of composition effect and the amount of pre-heat release in the end gas during a flame propagation; therefore, it is understood that ERF10 shows the most sensitive composition effect due to its pre-heat release characteristic. On the other hand, ERF with higher ethanol content was more sensitive to temperature effect by external-EGR on the ignition delay. It is found out that the amount of temperature effect depends mainly on latent heat of fuel; therefore, high latent heat of ethanol in ERF leads to its being influenced more by temperature effect. Consequently, ERF10 has the highest external-EGR sensitivity in anti-knock behavior at RON test condition, and it is further discussed that the optimum ERF for external-EGR strategy could vary from ERF0 to ERF10 according to different engine operating conditions. [ABSTRACT FROM AUTHOR]

A phosphatase and tensin homolog (PTEN) has been known to play multiple biological roles. However, role of PTEN in astrocyte activation is not clear yet. In the present study, the expression pattern of PTEN in the process of reactive gliosis was immunohistochemically examined in intracerebroventricular (i.c.v.) injected kainic acid mouse hippocampus. Mice were grouped into three; 30 min, 1 day and 7 days after kainic acid i.c.v. injection. Thirty minutes after kainic acid i.c.v. injection, astrocytes were activated and PTEN was weakly expressed in immature astrocytes. Seven days after kainic acid i.c.v. injection, PTEN expression was decreased in highly activated astrocytes showing extensively spindled shape. Immunofluorescence double labeling experiment showed that PTEN was expressed in glial fibrillary acidic protein-positive astrocytes. These findings suggest that PTEN might have a role in early stage of reactive astrogliosis in vivo. [Copyright &y& Elsevier]

A novel α-tubulin gene (α6) was cloned from a genomic library of Naegleria gruberi strain NB-1 and characterized. The open reading frame of α6 contained 1359 nucleotides encoding a protein of 452 amino acids (aa) with a calculated molecular weight of 50.5 kDa. The nucleotide sequence of the open reading frame of α6 showed considerable divergence (68.4% identity) when compared with previously cloned N. gruberi α-tubulin genes, which share about 97% identity in DNA sequences. The deduced aa sequence of α6-tubulin was 61.9% identical to that of α13-tubulin, which was cloned from the same strain, and showed similar identities to those of α-tubulins from other species (54∼62%). These data showed that α6-tubulin is one of the most divergent α-tubulins so far known. α6-tubulin was found to be expressed in actively growing cells and repressed quickly when these cells were induced to differentiate. Immunostaining with an antibody against α6-tubulin showed that α6-tubulin is present in the nuclei and mitotic spindle-fibers but absent in flagellar axonemes or cytoskeletal microtubules. These data finally established the presence of an α-tubulin that is specifically utilized for spindle-fiber microtubules and distinct from the flagellar axonemal α-tubulins in N. gruberi, hence confirmed the multi-tubulin hypothesis in this organism. [Copyright &y& Elsevier]

Abstract Despite the significant influences of the rigid cyclic ring structure on the good thermal and mechanical characteristics of poly (1,4-cyclohexylenedimethylene terephthalate) (PCT), steric hindrance by the cyclohexylene group interferes with glycolysis, an important chemical recycling route for poly (ethylene terephthalate) (PET) derivatives. To confirm the effects of chemical structure on the reaction, bis(4-hydroxymethyl)cyclohexylmethyl terephthalate (BHCHT), a model compound for PCT, was synthesized and compared with bis(2-hydroxyethyl) terephthalate (BHET), a model compound for PET, in transesterification reactions under zinc catalytic conditions. The rate of transesterification of BHCHT was 1/3 of that of BHET, and this retarded reaction rate was dramatically increased by up to 4 times when a catalytic amount of alkoxy species was combined with the zinc catalyst. The conditions of alkoxide combined with the zinc catalyst were applied to the glycolysis of PCT; the glycolytic reaction rate was three times higher than that with the conventional zinc acetate and the glycolysis product was produced with 82% yield. Highlights • Effective glycolysis process for PET derivatives with sterically hindered substituent. • Enhanced catalytic condition for glycolysis was achieved through model compound studies. • Combined catalytic conditions with alkoxy species was found to be highly reactive in transesterification. [ABSTRACT FROM AUTHOR]

Li 3 Sc(BO 3) 2 , an orthoborate polycrystalline compound, was synthesised using the solid-state synthesis method as a pure and Dy 2 O 3 -doped material. Dy3+ ions were used in various concentrations (from 1 to 6 mol. %). The experimental powder X-ray diffraction data and calculated Rietveld refined data are found to be in good agreement, verifying the effectiveness of the synthesis procedure. The luminescence studies were performed under the excitations of X-ray, proton beam, and UV light. The success of radioluminescence studies verifies the prospects of the Dy3+-doped compound for its application as a radiation scintillator in imaging. The experimental study of cross-relaxation processes confirms the lack of potential evidence of the quenching of the emission peak at 765 nm through the absorption via 6H 15/2 → 6F 3/2 electronic transition cross-relaxation channel −1. The CIE 1931 colour coordinates and correlated colour temperatures were determined for all doped samples under X-ray, proton beam, and photoluminescence excitations. The obtained combined emission colour appeared in the warm white region, unlike many other Dy3+-doped phosphors that suffer suppression of luminescence through the cross-relaxation process. • Pure and Dy3+ doped Li 3 Sc(BO 3) 2 phosphors were synthesised. • The phase purity was revealed by the Rietveld refining method. • The estimated optical bandgap is 3.13 eV for the pure Li 3 Sc(BO 3) 2. • Obsolete cross-relaxation at CRC-1 allow a moderately intense emission peak at 765 nm. • CIE 1931 coordinates and CCT identify the emission colour tone as warm white. [ABSTRACT FROM AUTHOR]

• Proposed a quantitative approach for measuring network resilience. • The network resilience is defined as a function of component resilience. • Developed a network resilience enhancement model under budget limit. This paper proposes a quantitative approach for measuring the resilience of the network components and the network itself. This study introduces a conceptual framework featuring the ability of the network system to adopt alternative plans when a component is disrupted. As a first step toward measuring network resilience, the component resilience is defined and quantified as a function of criticality, disruption frequency, disruption impact, and recovery capability. This quantification approach reflects the effect of component level disruption on the network. Hence, it is proposed that the network resilience is measured by the resilience of network component having the lowest resilience index. Efforts to enhance network resilience often require financial resources. Therefore, an optimization model is further introduced to maximize the network resilience under budget constraint through reinforcing the weakest components in the network. The proposed approach can help decision-makers assess the network resilience status and compare with it other networks, identify and improve components with low resilience, evaluate the cost of resilience improvement, and determine the extent of enhancement that can be achieved under a given budget limitation. Numerical experiments are conducted to illustrate our methodology using a supply chain network and a power network. Both examples show that considering the ability of the network to use alternative plans can enhance network resilience and result in lower demand loss when a disruption occurs. [ABSTRACT FROM AUTHOR]

The kinetics of prompt dissociation involves rovibrationally excited species (generally formed by exothermic reactions) which may dissociate or isomerize prior to thermalization via collisions with the bath gas. Treating such rovibrationally excited species (so-called "hot" species) with standard kinetic phenomenology may result in incorrect macroscopic representation of their reactivity. This work presents the first fully automated methodology for the calculation of prompt effects of a chosen species in a kinetic mechanism, including (i) reaction selection; (ii) theoretical calculation of rate constants and prompt branching fractions; and (iii) final rate constant fitting. The energy partition between hot fragments is estimated using a variety of statistical models, including a new physically sound microcanonical statistical model based on the rovibrational density of states of the fragments. The methodology is validated against literature data for the prompt dissociations of HCO and C 3 H 7 radicals. The microcanonical statistical model is in better agreement with trajectory simulations for larger species and is thus applicable for practical systems that typically involve large molecules, for which direct dynamics calculations are impractical. The automated workflow is applied to the evaluation of the effects of prompt dissociation for two isomeric radicals C 4 H 7 1-3 (1-methylallyl) and C 4 H 7 1-4 (3-buten-1-yl). Twelve H-atom abstraction reactions are selected and the corresponding rate constants are computed with first principles theory. The microcanonical statistical model predicts that prompt dissociations of C 4 H 7 1-3 and C 4 H 7 1-4 are already significant at 1000 K, resulting in differences of up to an order of magnitude at 2000 K with respect to the phenomenological thermal rate constants. To illustrate the effects of prompt dissociation on simulations of experimental data, the calculated prompt rate constants are implemented in both CRECK and C3MechV3.3 kinetic mechanisms. Simulations of experimental flame data illustrate the noticeable impact of prompt dissociation kinetics on the high-temperature combustion reactivity of C 4 H 8 -1 and C 4 H 8 -2. [ABSTRACT FROM AUTHOR]