Initiation Mechanism Research Articles

Optimal selection of manufacturing enterprise financialization based on simulated annealing investment portfolio theory

The global market competition is becoming increasingly fierce, and manufacturing enterprises need to invest and expand. However, the traditional financial optimization of manufacturing enterprises has faced problems such as low efficiency and inaccurate search for the optimal solution, which has made manufacturing enterprises likely to face financial risks. The investment portfolio can enable enterprises to obtain the maximum profit on a certain risk level, or reduce their investment risk on a certain return level as far as possible. If the combinatorial optimization is realized, it can be applied to the optimal selection of manufacturing enterprises’ financialization. This article analyzed the respective characteristics of Genetic Algorithm (GA) and Simulated Annealing (SA) algorithms, and analyzed the combination of GA and SA algorithms to solve the optimal investment portfolio through GA-SA algorithm, thereby helping manufacturing enterprises to make the optimal choice for financialization. The experimental results of this article indicated that the GA-SA algorithm solved the problem of GA algorithm easily falling into local optima, SA algorithm’s initial temperature and generation mechanism, and improved the efficiency of finding the optimal solution. Meanwhile, the experimental results showed that the average optimal solutions of Genetic Algorithm, Simulated Annealing algorithm, and GA-SA algorithms for 36 stock portfolios in Enterprise 1 were 69, 69, and 107, respectively. The average optimal solutions of the three algorithms for 36 stock portfolios in Enterprise 2 were 73, 90, and 112, respectively. This proves that the number of optimal solutions searched by GA-SA algorithm is higher than that of GA and SA algorithm, and also proves that it is effective to use GA-SA algorithm to optimize investment portfolio and help manufacturing enterprises to make optimal financial choices.

Prediction of long-term visual outcome of idiopathic full-thickness macular hole surgery using optical coherence tomography parameters that estimate potential preoperative photoreceptor damage.

To identify optical coherence tomography (OCT) parameters that predict postoperative best corrected visual acuity (BCVA) and are based on recent understanding of the pathomechanism of idiopathic full thickness macular hole (iFTMH) formation and closure. A retrospective consecutive case series of patients who had macular hole (MH) surgery at our institution between 2016 and 2022 was performed. 32 eyes of 30 patients were selected with at least 12months of follow-up, closed MH and good quality OCT at each visit. Univariate correlation analysis, multiple logistic regression with forward stepwise selection, and Akaike's Information Criterion (AIC) were used to identify the best predictors for postoperative BCVA at 6 and 12months (M), and final (≥ 12M) visits, and a new OCT index was created. Abilities of best models/indices to predict < 0.30 logMAR (> 20/40) BCVA were compared to macular hole index (MHI) using the area under the receiver operating curve (AU-ROC) analysis. Statistical analysis revealed base diameter (B) (6M), preoperative BCVA and B (12M) and smaller ELM-GCL distance (A), and B (final visit) as predictors for postoperative BCVA. AU-ROC analysis indicated greatest AUC at 6M for MHI and B (0.797, p = 0.004 and 0.836 p = 0.001, respectively) and for the new A/B index at 12M and final visit (0.844, p = 0.002 and 0.913, p = 0.003, respectively). Our study suggests that MHI and B can be useful predictors of short term BCVA while the new A/B index that incorporates OCT parameters indicating potential preoperative photoreceptor damage may be a good predictor for long term postoperative BCVA. Our findings support the theory that initial hole formation mechanisms and photoreceptor damage define visual prognosis.

Effects of squeeze casting on microstructure and mechanical properties of Al–5Cu–1Mn–0.3Ti alloy

In this work, the microstructure and mechanical properties of the Al–5Cu–1Mn–0.3Ti alloy prepared by different casting processes were investigated. The results showed that direct squeeze casting can further refine the grain and θ-Al2Cu phase, which is favourable to the uniform distribution of the θ-Al2Cu phase. The fluffy θ-Al2Cu/α-Al interface was caused by the severe pressure loss during the indirect squeeze casting process. The strength and elongation of direct squeeze casting alloy are 508 MPa and 18.5%, which are 40.3% and 123% higher than those of the alloys of indirect squeeze casting. The in situ tensile experiments revealed that the crack initiation mechanism of the indirect squeeze casting alloy is the debonding of the θ-Al2Cu phase at the grain boundaries.

A model with multiple intracranial aneurysms: possible hemodynamic mechanisms of aneurysmal initiation, rupture and recurrence

BackgroundHemodynamic factors play an important role in aneurysm initiation, growth, rupture, and recurrence, while the mechanism of the hemodynamic characteristics is still controversial. A unique model of multiple aneurysms (initiation, growth, rupture, and recurrence) is helpful to avoids the confounders and further explore the possible hemodynamic mechanisms of aneurysm in different states.MethodsWe present a model with multiple aneurysms, and including the states of initiation, growth, rupture, and recurrence, discuss the proposed mechanisms, and describe computational fluid dynamic model that was used to evaluate the likely hemodynamic effect of different states of the aneurysms.ResultsThe hemodynamic analysis suggests that high flow impingement and high WSS distribution at normal parent artery was found before aneurysmal initiation. The WSS distribution and flow velocity were decreased in the new sac after aneurysmal growth. Low WSS was the risk hemodynamic factor for aneurysmal rupture. High flow concentration region on the neck plane after coil embolization still marked in recanalized aneurysm.ConclusionsAssociations have been identified between high flow impingement and aneurysm recanalization, while low WSS is linked to the rupture of aneurysms. High flow concentration and high WSS distribution at normal artery associated with aneurysm initiation and growth, while after growth, the high-risk hemodynamics of aneurysm rupture was occurred, which is low WSS at aneurysm dome.

Threshold and real-time initiation mechanism of urban flood emergency response under combined disaster scenarios

Scientific and reasonable emergency response initiation mechanisms can provide important support for decision making regarding the emergency management of urban floods. However, there is a lack of a unified paradigm on how to calculate the threshold for emergency response initiation and reasonably initiate emergency response. Therefore, this study proposes a loss-driven urban flood emergency response initiation framework from the perspective of combined disasters. A discrimination mechanism of the emergency response initiation level was established based on the optimal threshold and loss function. And the rainfall event that occurred in Zhengzhou, China, on July 20, 2021, was taken as an example to realize real-time emergency response discrimination and initiation driven by forecast data. Results showed that the initiation time of the Level I emergency response using the proposed method was 9.5 h earlier than the time of the government release, thereby significantly increasing the preparation time for flood management personnel. In addition, the results of the optimal threshold selection indicated that the Natural Breakpoint method was the optimal method for loss threshold partitioning, with the comprehensive evaluation index (CEI) being 3.56–9.53% higher than those of the K-means, Equal Interval, and Quantile method. These results constitute a reference for urban emergency management and related research.

Revealing the mechanism of crack initiation and propagation in CGHAZ of S690QL welded joints through low-temperature impact tests with gradient setting of pendulum angle

As the most brittle areas of welded S690QL high-strength steel structures, coarse-grained heat-affected zone (CGHAZ) was crucial for the structural integrity of components. This paper designed an innovative low-temperature impact testing method with a gradient setting of pendulum angle to investigate the micro-mechanism of crack initiation and propagation in the CGHAZ of S690QL welded joints. The results reveal that continuous blocky M−A constituents were distributed along prior austenite grain boundaries (PAGBs), leading to stress concentration and crack initiation. During low-temperature impact processes, cracks propagate in a transgranular mode along {100} or {110} crystal planes. Due to the interaction between compressive stress and the crack tip, regions with high kernel average misorientation (KAM) such as PAGBs can divert the crack. The coarsening of prior austenite grains in the CGHAZ leads to a diminished hindering effect of PAGBs on crack propagation. The findings elucidate the complex relationship between microstructure and impact toughness of CGHAZ, providing insights into crack behavior and mechanisms in CGHAZ.

The impact of electronic effect on the dissociation mechanism of oxadiazole-based regioisomeric energetic materials

With the rapid development of synthesis methods for energetic materials, the regioisomerism effect is gaining increasing attention in the design of multifunctional energetic compounds and in the in-depth study of the relationship between structure and performance. Understanding regioisomerism in energetic materials and its impact on material performance can provide a theoretical basis for material improvement and design. In this paper, the influence of regioisomerism on the thermal stability of oxadiazole-based energetic materials 5,5′-bis(trinitromethyl)-3,3′-bi(1,2,4-oxadiazole) (BTBO) and trinitromethyl substituted β-bis(1,2,4-oxadiazole) (TSBO), which have a significant difference in the dissociation temperature, has been thoroughly investigated. The initial decomposition mechanism of the regioisomers is fully discussed, proving that the NO2-dissociation path is the main decomposition pathway, revealing that the difference in the energies of the main dissociative bonds of BTBO and TSBO is the direct cause of the different thermal stabilities. The regioisomerism on the thermal stability of BTBO and TSBO is investigated: the electronic effect increases the polarity and reduces the bond order of the main dissociative bond in BTBO, resulting in a lower dissociation temperature for BTBO.

Accelerating effect of metal ionic liquids for epoxy-anhydride copolymerization

One of the main drawbacks of high-performance epoxy-anhydride thermosets is slow cross-link kinetics requiring high temperature and long curing cycle. Herein, the accelerating effect of imidazolium metal-based ionic liquids (MILs) bearing (FeCl4)-, (ZnCl4)2-, and (CoCl4)2- anions on epoxy-anhydride copolymerization was investigated. It was observed that MILs accelerated bisphenol diglycidyl ether (DGEBA) − methylhexahydrophthalic anhydride (MHHPA) cross-linking, better than the reference catalysts (1-methylimidazole and 1-butyl-3-methylimidazolium chloride), especially at low temperatures through their ability to activate a rapid anhydride ring opening and formation of carboxyl groups, which initiates polyesterification. A detailed investigation of the polymerization mechanism revealed the formation of alternating epoxy-anhydride copolymers although several MILs-induced initiation mechanisms were detected. Despite the multiple-initiation consisting of imidazole, counter anion, and polyesterification pathways, the cross-linking kinetics was successfully fitted up to vitrification by the Kamal-Sourour model. Finally, MILs-induced cross-linking leads to homogeneous network build-up enabling to produce thermosetting materials with an increased cross-link density, a glass transition temperature above 150 °C, and excellent thermal stability.

Very high cycle fatigue of a notched Ni-based single crystal superalloy at high temperature

A new notched geometry has been developed for ultrasonic fatigue testing of CMSX-4 single crystal Ni-based superalloy specimens at 1000 °C. Ultrasonic fatigue tests were carried out at 1000 °C, R = -1 and 20 kHz using this new geometry. Two competing crack initiation mechanisms were identified for the studied range of fatigue lives: internal crack initiation from a casting pore associated to a rough zone (RZ) formation and surface crack initiation assisted by oxidation. Failure modes associated to the identified fatigue crack initiation mechanisms are discussed. Comparing fresh fractographic evidence with available results from the literature, it is shown that fatigue crack nucleation and first stages of crack propagation seem to govern VHCF fatigue life.

On reinforcing the friction stir weld joints of AA5086-H116 using the plasma spray coatings

The fatigue properties of friction stir weld joints of AA5086-H116 alloy, reinforced with Al2O3 particles using the plasma spray coating method, were investigated after single and double weld passes. A relatively uniform distribution of reinforced particles was achieved with superior properties, even higher than that of the parent alloy. The reinforced joints had enhanced hardness as well as joint efficiency, the double pass being superior to the single pass, but at the cost of reduced total elongation. Furthermore, the reinforced double-pass joints exhibited a remarkable ∼ 55%, ∼ 14%, and ∼ 89% increase in fatigue strength compared to the as-weld, the base material, and single-pass joints, respectively. The fractographic examination mainly revealed a defect-free crack initiation mechanism with a few cases of the ones induced by defects. The superior fatigue performance was mainly attributed to the uniform spatial and size distribution of fine Al2O3 particles within the weld nugget zone, thanks to the novel weld reinforcement method used in this study, which provides a promising avenue for improving the fatigue properties of weld joints.

Factor-Dependent Internal Ribosome Entry Site and -1 Programmed Frameshifting Signal in the Bemisia-Associated Dicistrovirus 2

The dicistrovirus intergenic (IGR) IRES uses the most streamlined translation initiation mechanism: the IRES recruits ribosomes directly without using protein factors and initiates translation from a non-AUG codon. Several subtypes of dicistroviruses IRES have been identified; typically, the IRESs adopt two -to three overlapping pseudoknots with key stem-loop and unpaired regions that interact with specific domains of the ribosomal 40S and 60S subunits to direct translation. We previously predicted an atypical IGR IRES structure and a potential -1 programmed frameshift (-1 FS) signal within the genome of the whitefly Bemisia-associated dicistrovirus 2 (BaDV-2). Here, using bicistronic reporters, we demonstrate that the predicted BaDV-2 -1 FS signal can drive -1 frameshifting in vitro via a slippery sequence and a downstream stem-loop structure that would direct the translation of the viral RNA-dependent RNA polymerase. Moreover, the predicted BaDV-2 IGR can support IRES translation in vitro but does so through a mechanism that is not typical of known factorless dicistrovirus IGR IRES mechanisms. Using deletion and mutational analyses, the BaDV-2 IGR IRES is mapped within a 140-nucleotide element and initiates translation from an AUG codon. Moreover, the IRES does not bind directly to purified ribosomes and is sensitive to eIF2 and eIF4A inhibitors NSC1198983 and hippuristanol, respectively, indicating an IRES-mediated factor-dependent mechanism. Biophysical characterization suggests the BaDV-2 IGR IRES contains several stem-loops; however, mutational analysis suggests a model whereby the IRES is unstructured or adopts distinct conformations for translation initiation. In summary, we have provided evidence of the first -1 FS frameshifting signal and a novel factor-dependent IRES mechanism in this dicistrovirus family, thus highlighting the diversity of viral RNA-structure strategies to direct viral protein synthesis.

Corrosion protection failure test analysis of the initial damaged cable ICCP mechanism

Given the corrosion protection failure of the cable-stayed bridge cable in the actual project, the impressed current cathodic protection (ICCP) technology was used to carry out the anti-corrosion tests from steel wire scale to cable scale, analyze the corrosion protection characteristics of steel wire ICCP, deduce the corrosion factor ICCP diffusion model, and reveal the space ICCP mechanism of the initial damaged cable. The analysis shows that ICCP can effectively inhibit the corrosive effect of steel wires and cables, and reduce the loss of mechanical properties of steel wires. Its protective efficiency increases with an increase in the absolute value of its protective potential and decreases with an increase in the dead load level. ICCP has a blocking effect on the diffusion of corrosion factors in the cable space, and the corrosion spatial distribution range, corrosion factor concentration, and diffusion coefficient of the initial damaged cable decrease significantly with the increase in the absolute value of the protection potential. The open circuit potential moves in a positive direction with the development of the corrosion process, and the blocking effect of corrosive factor diffusion is transformed from the joint participation by sacrificial anode cathodic protection and ICCP to the dominance of ICCP.

The Phenomenon of a Cathode Spot in an Electrical Arc: The Current Understanding of the Mechanism of Cathode Heating and Plasma Generation

A vacuum arc is an electrical discharge, in which the current is supported by localized cathode heating and plasma generation in minute regions at the cathode surface called cathode spots. Cathode spots produce a metallic plasma jet used in many applications (microelectronics, space thrusters, film deposition, etc.). Nevertheless, the cathode spot is a problematic and unique subject. For a long time, the mechanisms of spot initiation, time development, instability, high mobility, and behavior in magnetic fields have been described by approaches that caused some controversy. These spot characteristics were discussed in numerous publications over many years. The obscurity and confusion of different studies created the impression that the cathode spot is a mysterious phenomenon. In the present work, a number of typical representative publications are reviewed with the intention of clarifying problems and contradictions. Two main theories of cathodic arcs are presented along with an analysis of the experimental data. One of the approaches illustrates the cathode heating by Joule energy dissipation (volume heat source, a sharp rise in current density, etc.), nearly constant cathode potential drop, and other certain initial conditions. On the other hand, a study using a mathematically closed approach shows that the spot initiation and development are determined not by electron emission current rise but by a rise in arc power density, affecting heat sources including the energy of ion flux to the cathode (surface heat source).

Unveiling the Initiation Route of Coronal Mass Ejections through Their Slow Rise Phase

Understanding the early evolution of coronal mass ejections (CMEs), in particular their initiation, is the key to forecasting solar eruptions and induced disastrous space weather. Although many initiation mechanisms have been proposed, a full understanding of CME initiation, which is identified as a slow rise of CME progenitors in kinematics before impulsive acceleration, remains elusive. Here, with a state-of-the-art thermal magnetohydrodynamics simulation, we determine a complete CME initiation route in which multiple mainstream mechanisms occur in sequence yet are tightly coupled. The slow rise is first triggered and driven by the developing hyperbolic flux tube (HFT) reconnection. Subsequently, the slow rise continues as driven by the coupling of the HFT reconnection and the early development of torus instability. The end of the slow rise, i.e., the onset of the impulsive acceleration, is induced by the start of the fast magnetic reconnection coupled with the torus instability. These results unveil that CME initiation is a complicated process involving multiple physical mechanisms, thus being hardly resolved by a single initiation mechanism.

Alfvén pulse driven spicule-like jets in the presence of thermal conduction and ion-neutral collision in two-fluid regime.

We present the formation of quasi-periodic cool spicule-like jets in the solar atmosphere using 2.5-D numerical simulation in two-fluid regime (ions+neutrals) under the presence of thermal conduction and ion-neutral collision. The nonlinear, impulsive Alfvénic perturbations at the top of the photosphere trigger field aligned magnetoacoustic perturbations due to ponderomotive force. The transport of energy from Alfvén pulse to such vertical velocity perturbations due to ponderomotive force is considered as an initial trigger mechanism. Thereafter, these velocity perturbations steepen into the shocks followed by quasi-periodic rise and fall of the cool jets transporting mass in the overlying corona. This article is part of the theme issue 'Partially ionized plasma of the solar atmosphere: recent advances and future pathways'.

How transportability analysis can be useful for cumulative theory testing in management research

Moving management science forward by publishing research aimed at theory testing and refinement is the mission of the Journal of Management Scientific Reports. One way to test and refine a theory is through constructive replication studies. If X→Y (the causal effect of X on Y) is found in an initial study, what assumptions and mechanisms are required to expect that X→Y would also be found in a subsequent study, when the population differs between the initial and subsequent studies? What structural discrepancies between source and target populations would render transporting the knowledge obtained from one study to another impossible? Whereas generalizability is concerned with making inferences based on a possibly biased sample drawn from a focal population about the focal population, transportability refers to the conditions under which a transfer of causal knowledge across populations is valid. Researchers now have access to methods for identifying the conditions under which causal information learned from experiments would be valid in studies where ideal experiments cannot be conducted and where only passive observations can be collected. In this commentary, I explain how transportability analysis and its associated diagnostic tools from machine learning and artificial intelligence can be useful for cumulative theory testing in management research.

Mechanism of cross-level settlements and void accumulation of wide and conventional sleepers in railway ballast

AbstractThe cross-level and twist irregularities are the most dangerous irregularity types that could cause wheel unloading with the risk of derailments and additional maintenance expenses. However, the mechanism of the irregularities initiation and development is unclear. The motivation of the present study was the previous experimental studies on the application of wide sleepers in the ballasted track. The long-term track geometry measurements with wide sleepers show an enormous reduction of the vertical longitudinal irregularities compared to the conventional track. However, wide sleepers had higher twist and cross-section level irregularities. The present paper aims to explain the phenomenon by discrete element method (DEM) modeling the development process of sleeper inhomogeneous support at cross-level depending on the sleeper form. The DEM simulations show that the maximal settlement intensity is up to 3.5 times lower for a wide sleeper in comparison with the conventional one. Nevertheless, the cross-level differential settlements are almost the same for both sleepers. The particle loading distribution after all loading cycles is concentrated on the smaller area, up to the half sleeper length, with fully unloaded zones under sleeper ends. Ballast flow limitation under the central part of the sleeper could improve the resilience of wide sleepers to the development of cross-level irregularities. The mechanism of initiation of the cross-level irregularity is proposed, which assumes the loss of sleeper support under sleeper ends. The further growth of inhomogeneous settlements along the sleeper is assumed as a result of the interaction of two processes: ballast flow due to dynamic impact during void closing and on the other side high pressure due to the concentration of the pressure under the middle part of the sleeper. The DEM simulation results support the assumption of the mechanism and agree with the experimental studies.

Prediction of initiation mechanism of three-dimensional penetrating single crack

Prediction of initiation mechanism of three-dimensional penetrating single crack

CaMKIIα mediates spermidine-induced memory enhancement in rats: A potential involvement of PKA/CREB pathway

Memory consolidation is associated with the regulation of protein kinases, which impact synaptic functions and promote synaptogenesis. The administration of spermidine (SPD) has been shown to modulate major protein kinases associated with memory improvement, including the Ca2+-dependent protein kinase (PKC) and cAMP-dependent protein kinase (PKA), key players in the cAMP response element-binding protein (CREB) activation. Nevertheless, the initial mechanism underlying SPD-mediated memory consolidation remains unknown, as we hypothesize a potential involvement of the memory consolidation precursor, Ca2+/calmodulin-dependent protein kinase II-α (CaMKIIα), in this process. Based on this, our study aimed to investigate potential interactions among PKC, PKA, and CREB activation, mediated by CaMKIIα activation, in order to elucidate the SPD memory consolidation pathway. Our findings suggest that the post-training administration of the CaMKII inhibitor, KN-62 (0.25 nmol, intrahippocampal), prevented the memory enhancement induced by SPD (0.2 nmol, intrahippocampal) in the inhibitory avoidance task. Through western immunoblotting, we observed that phosphorylation of CaMKIIα in the hippocampus was facilitated 15 min after intrahippocampal SPD administration, resulting in the activation of PKA and CREB, 180 min after infusion, suggesting a possible sequential mechanism, since SPD with KN-62 infusion leads to a downregulation in CaMKIIα/PKA/CREB pathway. However, KN-62 does not alter the memory-facilitating effect of SPD on PKC, possibly demonstrating a parallel cascade in memory acquisition via PKA, without modulating CAMKIIα. These results suggest that memory enhancement induced by SPD administration involves crosstalk between CaMKIIα and PKA/CREB, with no PKC interaction.

Developments of a fundamental mechanism for initiation of solar eruptions

Developments of a fundamental mechanism for initiation of solar eruptions