Sequence Of Transitions Research Articles

A Deadlock-Free Hybrid Estimation of Distribution Algorithm for Cooperative Multi-UAV Task Assignment With Temporally Coupled Constraints

This study addresses the cooperative multi unmanned aerial vehicles task assignment problem (CMTAP) with temporally coupled constraints and aims to find a feasible assignment to minimize the equivalent distances of all tasks. We first present a mixed-integer linear programming model of CMTAP. To solve the undesirable deadlocks of CMTAP, a Petri net amender is constructed based on a candidate solution, and a deadlock-free solution is equivalent to a feasible transition sequence that can be fired sequentially in the corresponding amender. With this amender, we present a Petri net-based deadlock amending method (PDAM) with polynomial time complexity to convert a deadlocked solution into a deadlock-free solution. Also, a deadlock-free hybrid estimation of distribution algorithm (DHEDA) is developed for CMTAP by embedding PDAM into the original EDA. To further improve the solution quality, we establish a local exploitation method, and an adaptive operational probability is used to balance the computational burden and local exploitation ability. Then a match-up based reassignment method is proposed to cope with time-sensitive targets. Finally, extensive computational experiments demonstrate that PDAM is more effective at solving deadlocks than graph-based methods, particularly for large-scale CMTAP, and DHEDA outperforms existing algorithms when solving CMTAP.

Tuning of Multi-stability Profile and Transition Sequence of Stacked Miura-Origami Metamaterials

Multi-stable origami structures and metamaterials possess unique advantages and could exhibit multiple stable three-dimensional configurations, which have attracted widespread research interest and held promise for applications in many fields. Although a great deal of attention has been paid to the design and application of multi-stable origami structures, less knowledge is available about the transition sequence among different stable configurations, especially in terms of the fundamental mechanism and the tuning method. To fill this gap, with the multi-stable dual-cell stacked Miura-ori chain as a platform, this paper explores the rules that govern the configuration transition and proposes effective methods for tuning the transition sequence. Specifically, by correlating the energy evolution, the transition paths, and the associated force–displacement profiles, we find that the critical extension/compression forces of the component cells play a critical role in governing the transition sequence. Accordingly, we summarize the rules for predicting the transition sequence: the component cell that first reaches the critical force during quasi-static extension or compression will be the first to undergo a configuration switch. Based on these findings, two methods, i.e., a design method based on crease-stiffness assignment and an online method based on internal pressure regulation, are proposed to tune the stability profile and the transition sequence of the multi-stable origami structure. The crease-stiffness design approach, although effective, cannot be employed for online tuning once the prototype has been fabricated. The pressure-based approach, on the other hand, has been shown experimentally to be effective in adjusting the constitutive force–displacement profiles of the component cells and, in turn, tuning the transition sequence according to the summarized rules. The results of this study will advance the state of the art of origami mechanics and promote the engineering applications of multi-stable origami metamaterials.

Sequential self-propelled morphology transitions of nanoscale condensates enable a cascade jumping-droplet condensation

Jumping-droplet condensation, namely the out-of-plane jumping of condensed droplets upon coalescence, has been a promising technical innovation in the fields of energy harvesting, droplet manipulation, thermal management, etc., yet is limited owing to the challenge of enabling a sustainable and programmable control. Here, we characterized the morphological evolutions and dynamic behaviors of nanoscale condensates on different nanopillar surfaces, and found that there exists an unrevealed domino effect throughout the entire droplet lifecycle and the coalescence is not the only mechanism to access the droplet jumping. The vapor nucleation preferentially occurs in structure intervals, thus the formed liquid embryos incubate and grow in a spatially confined mode, which stores an excess surface energy and simultaneously provides a asymmetric Laplace pressure, stimulating the trapped droplets to undergo a dewetting transition or even a self-jumping, which can be facilitated by the tall and dense nanostructures. Subsequently, the adjacent droplets merge mutually and further trigger more multifarious self-propelled behaviors that are affected by underlying surface nanostructure, including dewetting transition, coalescence-induced jumping and jumping relay. Moreover, an improved energy-based model was developed by considering both the surface structure properties and the nano-physical effects, the theoretical prediction not only extends the coalescence-induced jumping to the nanometer-sized droplets but also correlates the surface nanostructure topology to the jumping velocity. Such a domino effect of nucleation-growth-coalescence on the ultimate morphology of droplet may offer a new strategy for designing functional nanostructured surfaces that serve to orientationally manipulate, transport and collect droplets, and motivate surface engineers to realize a stable cascade jumping-droplet condensation and achieve its performance ceiling.

Revised and Extended Analysis of Ar vi

This paper analyzes the emission spectrum of Ar vi and adds new information about this ion. We use a capillary light source to study the Ar vi spectrum, presenting 39 line classifications for the first time, including one line in the ultraviolet region. A total of nine possible Ar vi lines in the ultraviolet between 3288 and 3440 Å are analyzed. We revised the wavelengths of the lines at 1284.01 and 1307.42 Å previously used to identify Ar vi in astronomical objects. The lifetimes, weighted transition rates (gA) and their estimated uncertainties, and cancellation factors are obtained using a Hartree–Fock calculation with energy parameters adjusted to fit the values of the experimental levels and modified to include core polarization effects. We analyze all the experimentally known transitions of the Ar vi spectrum, with particular attention to conflicting information. Isoelectronic sequences of energy levels and transitions, for which the trend is not a smooth curve, are analyzed. We revise previous studies where the information needed to support line classifications and level designations is incomplete.

Coexistence of single-particle and collective excitation in Ni61

The high spin states in 61 Ni have been studied using the fusion evaporation reaction, Ti( $^{14}$C,3n) $^{61}$Ni at an incident beam energy of 40 MeV. A Compton suppressed multi-HPGe detector setup, consisting of six Clover detectors and three single crystal HPGe detectors was used to detect the de-exciting $\gamma$ rays from the excited states. The level scheme has been extended up to an excitation energy of 12.8 MeV and a tentative J$_{\pi}$ = 35/2$^+$ . The low-lying negative parity levels are found to be generated by single particle excitation within the f p shell and also excitations to the g$_{9/2}$ orbitals as explained well with shell model calculations using the GXPF1Br+V M U (modified) interaction. Two rotational structure of regular E2 sequences with small to moderate axial deformation have been established at higher excitation energy. Most interestingly, two sequences of M1 transitions are reported for the first time and described as magnetic rotational bands. The shears mechanism for both the bands can be described satisfactorily by the geometrical model. The shell model calculation involving the cross shell excitation beyond the fp shell well reproduce the M1 and E2 sequences. The shell model predicted B(M1) values for the magnetic rotational band B1 show the decreasing trend with spin as expected with closing of the shears.

An Intriguing Array of Extrudate Patterns in Long‐Chain Branched Polymers During Extrusion

AbstractThe present study highlights a range of surface and volume extrudate patterns that can be detected during the extrusion flow of long‐chain branched polymers. Thus, four linear low‐density polyethylenes (LDPEs) have been extruded using a single‐screw extruder coupled to an inline optical imaging system. The selected LDPEs are selected to outline the influence of molecular weight and long‐chain branching on the types of melt flow extrusion instabilities (MFEI). Through the inline imaging system, space–time diagrams are constructed and analyzed via Fourier‐transformation using a custom moving window procedure. Based on the number of characteristic frequencies, peak broadness, and whether they are surface or volume distortions, three main MFEI types, distinct from those typically observed in linear and short‐chain branched polymers, are identified. The higher molecular weight, low long‐chain branching LDPEs exhibited all three instability types, including a special type volume instability. Independently of the molecular weight, higher long‐chain branching appeared to have a stabilizing effect on the transition sequences by suppressing volume extrudate distortions or limiting surface patters to a form of weak intensity type.

The Role of MX Carbonitrides for the Particle-Stimulated Nucleation of Ferrite in Microalloyed Steel

The role of titanium and vanadium carbonitrides (Ti,V)(C,N) of the MX series on the austenite-to-ferrite transformation in microalloyed steels and their potential of acting as pre-nuclei for intragranular ferrite nucleation is examined experimentally and by computational simulation. Thermal treatments and single-hit compression tests are performed on a dilatometer and a Gleeble® 3800 thermomechanical simulator to investigate the phase transition and precipitation sequences within microalloyed steel. The analysis of the microstructure and examination of formed precipitates is carried out by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In situ observations are realized via high-temperature laser scanning confocal microscopy (HT-LSCM). The experimental results are compared to kinetic precipitation simulations for MX precipitates’ particle-stimulated intragranular ferrite formation using an on-particle nucleation model for ferrite on the surface of the MX carbonitrides. A particular focus is the comparison of precipitation trends between non-deformed and deformed samples. The physically appropriate modeling of MX precipitation kinetics in combination with intragranular ferrite formation serves as a basis for future industrial process optimizations without extensive experimental work.

Immersive University Model: A Tool to Increase Higher Education Competitiveness

The current paper substantiates the effectiveness of immersive learning applications for youth. Emphasis is placed on the fact that the “immersion” of students can be carried out not only through virtual and augmented reality but also in any constructed environment that provides any “immersion” in active and interactive teaching methods. A bibliometric analysis was conducted for the “immersive learning” search query to identify keywords and phrases’ main clusters and their relationships. Based on the bibliometric analysis, the concept of forming an immersive learning model based on a sequential transition between the “dimensions” was formed. The model is developed considering the degree of involvement in the learning scenarios. A multidimensional classification model for immersive learning tools is proposed. A university case of building an immersive learning environment as part of the “electronic university” information system is presented. A technological solution is proposed for evaluating the effectiveness of testing immersive learning tools.

Transitions in daily search tactics: during the cross-app interaction search process

PurposeCross-app interactive search has become the new normal, but the characteristics of their tactic transitions are still unclear. This study investigated the transitions of daily search tactics during the cross-app interaction search process.Design/methodology/approachIn total, 204 young participants' impressive cross-app search experiences in real daily situations were collected. The search tactics and tactic transition sequences in their search process were obtained by open coding. Statistical analysis and sequence analysis were used to analyze the frequently applied tactics, the frequency and probability of tactic transitions and the tactic transition sequences representing characteristics of tactic transitions occurring at the beginning, middle and ending phases. FindingsCreating the search statement (Creat), evaluating search results (EvalR), evaluating an individual item (EvalI) and keeping a record (Rec) were the most frequently applied tactics. The frequency and probability of transitions differed significantly between different tactic types. “Creat? EvalR? EvalI? Rec” is the typical path; Initiate the search in various ways and modifying the search statement were highlighted at the beginning phase; iteratively creating the search statement is highlighted in the middle phase; Moreover, utilization and feedback of information are highlighted at the ending phase. Originality/valueThe present study shed new light on tactic transitions in the cross-app interactive environment to explore information search behaviour. The findings of this work provide targeted suggestions for optimizing APP query, browsing and monitoring systems.

Interfacial self-transportation via controlled wettability transition for directed self-assembly

Wettability transition is a significant responsive mechanism which is widely applied to construct smart materials and systems. The broad-spectrum responsiveness of the wettability transition makes it a promising way to expand innovative applications. Here, we develop a track-guided self-transportation system mediated by sequential wettability transition accompanied with capillary transportation. Alkaline fuel is loaded into polydimethylsiloxane (PDMS) cuboid to trigger the wettability transition of distributed superhydrophobic tracks laid in shallow water. After the wettability transition, the induced capillary force can propel the repetitive track-to-track transportation of PDMS. Importantly, the spacing between adjacent tracks is rationally designed based on multiple factors including threshold of wettability transition, diffusion kinetics and capillary interaction. Furthermore, the track-guided transportation system is applied to realize directed self-assembly of multiple PDMS building blocks for designated configuration, which increases the complexity and intelligence of self-assembly systems.

Joint experimental and theoretical study of bulk Y2O3 at high pressure

We report a joint experimental and theoretical study of the structural and vibrational properties of C-type bulk Y2O3 under hydrostatic compression. The combination of high-pressure X-ray diffraction and Raman scattering experimental measurements with ab initio theoretical calculations on bulk Y2O3 allows us to confirm the cubic (C-type) – monoclinic (B-type) – trigonal (A-type) phase transition sequence on the upstroke and the trigonal-monoclinic phase transition on the downstroke. This result reconciles with the results already found in related rare-earth sesquioxides of cations with similar ionic radii as Y, such as Ho2O3 and Dy2O3, and ends with the controversy regarding the existence of the intermediate monoclinic phase between the cubic and trigonal phases in pure bulk Y2O3 on the upstroke. As a byproduct, the good agreement between experimental and calculated results allows us to use extensive theoretical data to discuss the structural and vibrational behavior of the three phases of Y2O3 under compression, thus allowing a more detailed understanding of the effect of pressure on rare-earth sesquioxides than previous studies.

Structural, Electric and Dynamic Properties of (Pyrrolidinium)3[Bi2I9] and (Pyrrolidinium)3[Sb2I9]: New Lead-Free, Organic-Inorganic Hybrids with Narrow Band Gaps.

Hybrid organic-inorganic iodides based on Bi(III) and Sb(III) provide integrated functionalities through the combination of high dielectric constants, semiconducting properties and ferroic phases. Here, we report a pyrrolidinium-based bismuth (1) and antimony (2) iodides of (NC4H10)3[M2I9] (M: Bi(III), Sb(III)) formula which are ferroelastic at room temperature. The narrow band gaps (~2.12 eV for 1 and 2.19 eV for 2) and DOS calculations indicate the semiconducting characteristics of both materials. The crystal structure consists of discrete, face-sharing bioctahedra [M2I9]3- and disordered pyrrolidinium amines providing charge balance and acting as spacers between inorganic moieties. At room temperature, 1 and 2 accommodate orthorhombic Cmcm symmetry. 1 displays a complex temperature-induced polymorphism. It is stable up to 525 K and undergoes a sequence of low-temperature phase transitions (PTs) at 221/222 K (I ↔ II) and 189/190 K (II ↔ III) and at 131 K (IV→III), associated with the ordering of pyrrolidinium cations and resulting in Cmcm symmetry breaking. 2 undergoes only one PT at T = 215 K. The dielectric studies disclose a relaxation process in the kilohertz frequency region, assigned to the dynamics of organic cations, described well by the Cole-Cole relation. A combination of single-crystal X-ray diffraction, synchrotron powder diffraction, spin-lattice relaxation time of 1H NMR, dielectric and calorimetric studies is used to determine the structural phase diagram, cation dynamics and electric properties of (NC4H10)3[M2I9].

Competition between the Ni and Fe Redox in the O3-NaNi1/3Fe1/3Mn1/3O2 Cathode Material for Na-Ion Batteries

Sodium-ion batteries are attracting great attention due to their low cost and abundance of sodium. The O3-type NaNi1/3Fe1/3Mn1/3O2 layered oxide material is a promising candidate for positive electrodes (cathodes) in Na-ion batteries. However, its stable electrochemical performance is restricted by the upper voltage limit of 4.0 V (vs Na/Na+), which allows for reversibly removing 0.5–0.55 Na+ per formula unit, corresponding to the capacity of 120–130 mAh·g–1. Further reduction of sodium content inevitably accelerates capacity degradation, and this issue calls for a detailed study of the redox reactions that accompany the electrochemical (de)intercalation of a large amount of sodium. Here, we present operando and ex situ studies using powder X-ray diffraction and X-ray absorption spectroscopy combined with 57Fe Mössbauer spectroscopy. Our approach reveals the sequence of the redox transitions that occur during the charge and discharge of O3-NaNi1/3Fe1/3Mn1/3O2. Our data show that in addition to nickel and iron cations oxidizing to M+4, a part of iron transforms into the “3 + δ” state owing to the fast electron exchange Fe3+ + Fe4+ ↔ Fe4+ + Fe3+. This process freezes upon cooling the material to 35 K, producing Fe4+ cations, some of which occupy tetrahedral positions.

Hysteretic electronic phase transitions in correlated charge density wave state of 1T−TaS2

The layered transition metal dichalcogenide $1T\text{\ensuremath{-}}{\mathrm{TaS}}_{2}$ has evoked great interest owing to its particularly rich electronic phase diagram including different charge density wave (CDW) phases. However, few studies have focused on its hysteretic electronic phase transitions based on the in-depth discussion of the delicate interplay among temperature-dependent electronic interactions. Here, we report a sequence of spatial electronic phase transitions in the hysteresis temperature range (160--230 K) of $1T\text{\ensuremath{-}}{\mathrm{TaS}}_{2}$ via variable-temperature scanning tunneling microscopy. Several emergent electronic states are investigated at multiscale during the commensurate CDW--triclinic CDW (CCDW-TCDW) phase transitions: a spotty-CDW state above $\ensuremath{\sim}160\phantom{\rule{0.28em}{0ex}}\mathrm{K}$, a network-CDW (NCDW) state above $\ensuremath{\sim}180\phantom{\rule{0.28em}{0ex}}\mathrm{K}$ during the warmup process, a belt-TCDW state below $\ensuremath{\sim}230\phantom{\rule{0.28em}{0ex}}\mathrm{K}$, a NCDW state below $\ensuremath{\sim}200\phantom{\rule{0.28em}{0ex}}\mathrm{K}$, and finally a mosaic-CDW state below $\ensuremath{\sim}160\phantom{\rule{0.28em}{0ex}}\mathrm{K}$ during cooldown from the TCDW phase. These emergent electronic states are associated with the delicate temperature-dependent competition and/or cooperation of stacking-dependent interlayer interactions, intralayer electron-electron correlations, and electron-phonon ($e\text{\ensuremath{-}}ph$) coupling of $1T\text{\ensuremath{-}}{\mathrm{TaS}}_{2}$. Our results not only provide insight to understand the hysteretic electronic phase transitions in the correlated CDW state, but also pave a way to realize more exotic quantum states by accurately and effectively tuning various interior interactions in correlated materials.

Local quantum Fisher information and local quantum uncertainty for general X states

A two-spin-1/2 Heisenberg XYZ model with Dzyaloshinsky–Moriya (DM) and Kaplan–Shekhtman–Entin-Wohlman–Aharony (KSEA) interactions in the presence of an inhomogeneous external magnetic field is considered at thermal equilibrium. Its density matrix has the general X form for which we derive explicit formulas for the local quantum Fisher information (LQFI) and local quantum uncertainty (LQU) directly in terms of model parameters. This allows us to perform a comparative study for the discord-type quantum correlations LQFI and LQU and to reveal a number of new features in their behavior. In particular, the sudden transitions of quantum correlations with a smooth change in temperature are found. Moreover, it is shown that there may be a sequence of such transitions for certain choices of interaction constants.

Algorithm for managing patients with papulopustular acne

The aim of the study was to study the efficacy and tolerability of the sequential use of the fixed combination of clindamycin + BPO in various clinical situations in real practice. Under our supervision there were 32 patients with mild-to-moderate and severe acne of papulo-pustular acne. Among them, 21 (65.6 %) female patients and 11 (34.4 %) male patients. The patients were divided into two groups: group 1 (teenage acne) of 17 people, group 2 (adult acne) of 15 people. The therapy algorithm included the use of a fixed combination of clindamycin + BPO (Zerkalin Intensive) for 4–5 weeks with a sequential transition to the use of a topical agent with adapalene for 6 months. All patients were prescribed specialized dermatocosmetics on an ongoing basis. As a result of therapy, after a week, there was a significantly significant change in all clinical symptoms of acne. So VAS (comedones) at the end of therapy decreased by 88.9 % (p < 0.01) and by 90.5 % (p < 0.01) in groups 1 and 2, respectively. Similar dynamics was noted in relation to inflammatory elements (papules, pustules). VAS (papules) in groups 1 and 2 decreased by 85.4 % (p < 0.01) and by 88.1 % (p < 0.01), VAS (pustules) – by 100 %. Thus, the use of a fixed combination of clindamycin + BPO causes a high therapeutic effect in relation to all clinical symptoms of acne.

Thermal Expansion and Phase Transformation up to 1200 °C of Metastable Aluminas Produced by Flame Spraying

The transition aluminas δ1 and the cubic, non-spinel-type η-Al2O3 were detected in addition to α-Al2O3 in flame-sprayed material. Their transitions from room temperature up to 1200 °C were investigated by high-temperature XRD measurements. Structural changes with time and temperature were observed for all transition aluminas (η-, δ1- and θ-Al2O3). The phases followed the expected transition sequence of η→δ1→θ→α and showed mainly linear, temperature-independent transition rates. Based on the determined thermal expansion of the phases, it is proposed that the metastable transitions are at least partly mechanically induced. In addition, a second-order phase transition from η→θ might be indicated around 1050–1075 °C by the determined trends of density.

Structural phase transitions, mechanical and electronic properties of [formula omitted] under high pressures via the first-principles calculations

High-pressure phases of ZrSe2 are predicted using the first-principles calculations combined with particle swarm optimization in the pressure range of 0 – 30 GPa. Three stable phases: the P3¯m1, C2/m and I4/mmm phases are identified, with the last two phases being predicted for the first time. The pressure-induced phase transition sequences are from the P3¯m1 phase to the C2/m phase, and then from the C2/m phase to the I4/mmm phase as the pressure increases. The related transition pressures are 3 GPa and 15 GPa, respectively. The thermal, dynamical and mechanical stabilities along with physical properties of these phases are investigated. In addition, the electronic band structures reveal that pressure-induced semiconductor-semimetal-metal transition occurs along with the structural phase transitions. Both the P3¯m1 and C2/m phases exhibit good catalytic activity in the hydrogen evolution reaction, calling for further experimental studies to verify.

A Weibit-Based sequential transit assignment model based on hyperpath graph and generalized extreme value network representation

This study aims to develop a weibit-based stochastic transit assignment model for situations in which passengers’ travel choice strategies are stochastic. The weibit choice model, which was originally developed for the stochastic traffic assignment problem, is adapted using a hyperpath graph network representation. Unlike the traditional logit model, the weibit model can account for the homogeneous perception variance problem. Besides, a joint choice network representation originated from the network generalized extreme value (N-GEV) model, known as the GEV network, is adopted to depict the correlation among the arcs within the hypergraph consisting of all efficient hyperpaths. The GEV network uses a link-based parameter, the degree of membership, to capture the overlap effect, which is thus well incorporated with the link-based transit assignment approach. For implementation, a link-based stochastic network loading approach is proposed for solving the weibit-based transit assignment model in the sequential process. This sequential assignment approach does not need to enumerate and store the transit hyperpaths in the solution process. This model is then extended to a stochastic transit equilibrium model under congestion conditions, which is formulated as a fixed-point problem. Thus, a recent fast line-search scheme, i.e., the Barzilai and Borwein step-size, is adopted for solving the stochastic transit equilibrium model. Numerical examples are provided to illustrate the features of the proposed weibit-based stochastic transit assignment model. A real transit network is used to demonstrate the algorithm efficiency and the detailed results of the weibit-based transit equilibrium model.

Geostatistical simulations of the spatial variability of hydraulic conductivity in an alluvial-marine sedimentary system in Beihai City, China

Sustainable aquifer management in coastal cities is becoming critically important due to the challenges of climate variability amidst population growth. Study of the aquifer heterogeneity is effective in highlighting the aquifer behavior. In this study, we took the case of Beihai to explore the heterogeneity of its subsurface system. 8629 samples from 111 boreholes were divided into four hydrofacies units as discrete geological variables according to their hydraulic conductivities (K) and used as input datasets for the models. Sequential Indicator Simulation (SISIM) and Transition Probability Geostatistical Simulation (T-PROGS) were employed to construct 3D hydrofacies stochastic models. The simulated results realistically represent horizontal river-driven sediment distribution and vertical deposition processes of K in the aquifer, where the northeastern part is mainly composed of low K and the southern part forms the main multi-layered aquifer system with progressively increasing medium and high K. With a comparative analysis on the ability of capturing geological characteristics using both SISIM and T-PROGS, it highlighted that SISIM reduces initial data requirements without the need of Gaussian transformation and is more broadly applicable, while T-PROGS prefers considering the internal correlation of hydrofacies units and is applicable in environments where lateral accumulation is prevalent. This study demonstrates the credibility of stochastic simulation methods in recreating complex costal sedimentary environments, which provide environment for further groundwater modeling and exploration. Multi-interleaved source data and more accurate algorithms will be integrated in aquifer heterogeneity as subsequent research priorities.