Formation Path Research Articles

Construction Project Organizational Capabilities Antecedent Model Construction Based on Digital Construction Context

In the context of high-quality development and the digital age, digital technology-enabled construction projects have become the only choice to promote organizational capabilities and innovation. However, the micro foundation of the organizational capabilities of construction projects has not been clarified, and its formation path is even less clear. This paper focuses on the characteristics of the times when digital technology and engineering construction are deeply integrated, conducts in-depth research on typical projects in the context of digital construction, and uses the qualitative research method of grounded theory to explore the antecedents of the formation of organizational capabilities. The results of the study establish a systematic antecedent model framework, including value integration, data traction, resource integration, technology integration, digital collaboration, and digital routines, and find out the “black box” process of the formation of construction project organizational capacities under the digital construction context. The conclusion of this study provides a theoretical basis and practical enlightenment for the construction of organizational capabilities of construction projects to cope with technological turbulence.

Boron depletion in Galactic early B-type stars reveals two different main sequence star populations

Context. The evolution and fate of massive stars are thought to be affected by rotationally induced internal mixing. The surface boron abundance is a sensitive tracer of this in early B-type main sequence stars. Aims. We test current stellar evolution models of massive main sequence stars which include rotational mixing through a systematic study of their predicted surface boron depletion. Methods. We construct a dense grid of rotating single star models using MESA, for which we employ a new nuclear network which follows all the stable isotopes up to silicon, including lithium, beryllium, boron, as well as the radioactive isotope aluminium-26. We also compile the measured physical parameters of the 90 Galactic early B-type stars with boron abundance information. We then compare each observed stars with our models through a Bayesian analysis, which yields the mixing efficiency parameter with which the star is reproduced the best, and the probability that it is represented by the stellar models. Results. We find that about two-thirds of the sample stars are well represented by the stellar models, with the best agreement achieved for a rotational mixing efficiency of ∼50% compared to the widely adopted value. The remaining one third of the stars, of which many are strongly boron depleted slow rotators, are largely incompatible with our models, for any rotational mixing efficiency. We investigate the observational incidence of binary companions and surface magnetic fields, and discuss their evolutionary implications. Conclusions. Our results confirm the concept of rotational mixing in radiative stellar envelopes. On the other hand, we find that a different boron depletion mechanism, and likely a different formation path, is required to explain about one-third of the sample stars. The large spread in the surface boron abundances of these stars may hold a clue to understanding their origin.

Unveiling the role of Cs ion in perovskite phase formation during solid–vapor reactions

The preparation of perovskite solar cells (PSCs) using a solid–vapor reaction has shown great potential due to its scalability and lack of organic solvent. The phase formation process in the solid–vapor reaction is crucial for the crystallization of perovskite films. Previous studies mainly introduced Cs into the solid–vapor reaction, but insufficient attention was paid to the role of Cs in purifying the phase formation path during the crystallization process. In this study, we investigated the effect of Cs on the phase formation process in the solid–vapor reaction and found that Cs can decrease the crystallinity of lead halide films, induce a purified phase formation process to prevent the formation of δ-phase and other impurity phases, regulate the crystallization rate of perovskite, and produce high-quality, low-defect perovskite films. The result was achieving a champion power conversion efficiency (PCE) of 21.54 % for a small area (0.148 cm2) and 18.65 % for larger mini-modules (5 × 5 cm2). Furthermore, the devices maintained over 80 % of their initial efficiencies after 450 h of continuous operation under AM 1.5 G irradiation. This work underscores the importance of purified phase formation paths in solid–vapor reactions for outstanding crystal quality in high-performance perovskite solar cells.

Formation path and kinetics of caking components from modified lignite in subcritical H2O–CO system

ABSTRACT Modification reaction of lignite in subcritical H2O–CO system can significantly increase its caking index to more than 90. Separating and extracting the caking components from modified lignite, exploring the formation path of caking components, and establishing a kinetic model for the generation of these components are of significant importance for lignite hydrogenation reaction control. The lignite modified reaction was carried out in subcritical D2O–CO systems using the isotope tracer method. The formation path of caking components was defined by solvent extraction–IRMS–GPC combination technology. The results show that the soluble substances of tetrahydrofuran (TS) and benzene (BS) are the main caking components causing the structural transformation of lignite (A). The separation of n-hexane soluble (NS) also has an effect on the caking index of the modified coal. In the hydrogenation caking component formation stage, the lignite pyrolysis fragments combine with active hydrogen generated by water gas shift reaction to form caking substances, that is, A → TS + BS + NS. The formation activation energy of caking components is in the range of 0.39–58.24 kJ/mol. In the polycondensation caking component conversion stage, three soluble substances are converted in the order of TS → BS → NS, and the activation energy for the formation of caking components is 31.710–57.616 kJ/mol.

A hybrid formation path planning based on the velocity-virtual spring method in dynamic environments

Purpose The purpose of this study is to propose a path-planning strategy based on the velocity-virtual spring method to realize collision-free tasks in dynamic environments and further improve the effect. Design/methodology/approach By considering factors such as the relative velocity and direction of dynamic obstacles, the repulsive force of the robot is improved, thereby enhancing the adaptability of the strategy and achieving flexible and effective avoidance against dynamic obstacles. The attraction formula has been designed to allow the robot to have better smooth changes and higher gradients near the target, helping robots better reach the target and follow formations. Moreover, to meet the demands of the various stages during the driving process, the null space behavioral control is used to solve multi-task conflict problems and strengthen formation coordination and control. Findings Comparison of the planning path and formation effects through simulation and physical experiments, the results of this study show that the algorithm proposed can successfully maintain formation stability and plan smooth and safe paths in static or dynamic environments. Originality/value This paper proposes a path-planning strategy based on the velocity-virtual spring method to plan collision-free paths for formation in dynamic environments.

Exploring the mechanisms of underground economy: A case study of the informal bicycle market in a southern China city

This paper aims to explore the typical mechanisms of the underground economic phenomenon through anthropological and grounded theoretical methodology through an ethnographic study on the site of an informal bicycle market in a city in South China. It investigates and analyzes the formation path and mechanism of the informal bicycle market. Data was collected through unobtrusive observation and in-depth interviews. It follows a grounded theory data analysis procedure based on multiple data sources, such as participant observations, interviews, prior literature, and news reports. The model illustrates how the informal bicycle market is formatted and the mechanisms to maintain its operations. The findings indicated that the development of the informal market affects the efficiency of social resource allocation and, in many cases, may erode the overall system of the national economy. The analysis of the formation path and mechanism of the underground economy represented by the informal market is of great significance for the sustainable development of the social economy.

Comparison of the Efficiency of B-O and B-C Bond Formation Pathways in Borane-Catalyzed Carbene Transfer Reactions Using α-Diazocarbonyl Precursors: A Combined Density Functional Theory and Machine Learning Study.

Lewis acidic boranes, especially tris(pentafluorophenyl)borane [B(C6F5)3], have emerged as metal-free catalysts for carbene transfer reactions of α-diazocarbonyl compounds in a variety of functionalization reactions. The established mechanism for how borane facilitates carbene generation for these compounds in the scientific community is based on the formation of a B-O (C=O) intermediate (path O). Herein, we report an extensive DFT study that challenges the notion of a ubiquitous path O, revealing that B-C(=N=N) bond formation (path C) for certain diazocarbonyl substrates proves to be the preferred pathway. This study elucidates, through the introduction of 22 various substituents on each side of the α-diazocarbonyl backbone, how the electron-donating and -withdrawing properties of substituents influence the competition between these B-O and B-C pathways. To elucidate the impact of the electronic features of diazo substrates on the competition between the O and C pathways in the studied dataset, we employed a machine learning approach based on the Random Forest model. This analysis revealed that substrates with higher electron density on the diazo-attached carbon, lower electron density on the carbonyl carbon, and more stable HOMO orbitals tend to proceed via path C. Furthermore, this study not only demonstrates that borane efficiency in facilitating N2 release is greatly affected by the nature of substituents on both sides of the α-diazocarbonyl functionality but also shows that for some substrates, borane is incapable of catalyzing the release of molecular nitrogen.

Nucleation mechanism of methane heterogeneous condensation under different driving forces

Clarifying alkane gas condensation characteristics is crucial to designing and optimizing liquefaction heat exchangers, which imposes higher demands on the microscopic understanding of alkane heterogeneous condensation. Thus, in this study, the condensation process of methane nucleation under different driving forces is investigated by molecular dynamics (MD) simulations. The dynamics characteristics of nucleation in methane heterogeneous condensation are analyzed by varying initial gas-phase pressure, cold wall temperature, and ethane content. The results showed that increasing the initial gas-phase pressure enhances intermolecular interactions, which alter the cluster formation path and significantly increase the methane gas nucleation rate from 1.997 × 1033/(m3·s) to 1.068 × 1034/(m3·s). While lowering the cold wall temperature promotes condensation by weakening the thermal motion of the gas molecules. Once condensation nuclei form in the system, the lower temperature conditions from lowering the cold wall temperature result in a higher growth rate of the clusters. Additionally, the addition of easily condensable component ethane can improve the condensation nucleation characteristics of low-saturated methane gas, facilitating the liquefaction of methane. This study aims to provide a microscopic understanding of the advancement of gas liquefaction technology by investigating the heterogeneous nucleation of alkane under different conditions from a microscopic perspective.

FF-RRT*: A Sampling-Based Planner for Multirobot Global Formation Path Planning

Abstract This article presents a collision-free global path planning approach for multirobot systems called flexible formation—rapidly exploring randomized trees* (FF-RRT*). The algorithm is based on RRT* and provides a flexible and efficient representation of the formation geometry independent of the number of robots. It is designed to generate optimal paths for multirobot systems in a five-dimensional configuration space comprising the formation centroid, orientation, and scaling. An affine transformation is used to convert the path in the configuration space to the workspace of the robots. The proposed method employs a new distance function that eliminates the need for tuning weights and a sampling scheme for scaling factors to avoid inter-robot collisions. FF-RRT* is experimentally demonstrated using nonholonomic wheeled mobile robots and is effective in planning the collective motion of the robots. Robots could collectively reach goals by squeezing through narrow gaps and splitting and merging around large obstacles.

Study on the Formation Mechanism of NOx Precursors During Density Functional Theory Pyrolysis of Leucine and Proline

ABSTRACT Incineration is an efficient method of resource utilization for kitchen waste. As an important stage of incineration, pyrolysis not only degrades kitchen waste but also generates pollutants such as nitrogen oxides. It is necessary to conduct in-depth research on the nitrogen conversion mechanism during its pyrolysis process. Most of the nitrogen in kitchen waste is concentrated in protein/amino acids. This article is based on the density functional theory calculation method, selecting typical compounds leucine and proline in kitchen waste as research objects, and studying their pyrolysis mechanism and the formation path of NOx precursors. A possible path for the cleavage of C-C/C-N bonds caused by hydrogen transfer to form NH3 and HCN has been proposed. Finally, it has been theoretically proven that the pyrolysis process of leucine tends to generate NH3 rather than HCN. And it was clarified that low energy barriers and high reaction rates are the reasons for the difference in production of these two NOx precursors. Meanwhile, the differences in the generation characteristics of NOx precursors for proline at different pyrolysis temperatures were theoretically explained. Finally, it was elucidated that leucine and proline preferentially undergo decarboxylation to complete the deoxygenation process, and the reason for the difference in CO production during the pyrolysis of the two amino acids was explained. In addition, this study found that the pyrolysis of leucine occurred preferentially than that of proline under the same conditions, and the yield of NOx precursor produced by leucine was higher than that of proline.

Effect of chemical structures and environmental factors on the thermal degradation mechanism of polyimide: Experiments and molecular dynamics simulations

The impact of chemical structure and environment on the thermal stability of polyimide (PI) was examined, and the degradation mechanism was determined using a combination of experiments and molecular simulations. Changes in mechanical properties and thermogravimetric analysis (TGA) were used to characterize the thermal stability of PI. Pyrolysis gas chromatography mass spectrometry (Py-GCMS) and thermogravimetric-infrared spectroscopy (TG-IR) were used to analyze the degradation products both qualitatively and quantitatively. Molecular simulation was employed to analyze the primary bond breakage and thermal degradation pathways of PI, as well as to investigate the effects of the chemical structure, atmosphere, and temperature on degradation properties. The findings indicated that p-benzene-structured 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA)/p-phenylenediamine (PDA) has the best thermal stability, whereas weak bonds like C–O–C in 4,4′-oxydianiline (ODA) and C–N in the 2-(4-aminophenyl)-1H-benzimidazol-5-amine (BIA) imidazole group decrease thermal stability. The formation path of low molecular weight products (CO2, CO, HCN, and NH3) and the potential degradation mechanism of PI were proposed. The process of PI thermal degradation accelerated by oxygen and high temperature was observed at the atomic level. Taken together, this work offers the possibility of monitoring the structural evolution of PI degradation process in real-time.

The effect of customer participation on brand preference: Do hotel brand type and star rating matter?

Drawing on value co-creation theory, this study proposes a novel model that incorporates the hotel brand type and star rating into the “customer participation—customer brand engagement—brand preference” model to explore their impacts on the formation of customer brand preferences. Data collected from 330 hotel patrons were analyzed to test the proposed model. The results suggest that customer participation positively affected three dimensions of brand engagement, viz., cognitive engagement, affective engagement, and behavioral engagement, which in turn positively influenced brand preference. Contrary to expectation, hotel brand type and star rating weakened the relationships between affective engagement and brand preference. This study enriches the discussion on the determinants of brand preference and describes its formation path. Implications, as well as future research opportunities, are offered.

Hydroxylamine-driven advanced oxidation process: Impact of key environmental factors on active species, reaction pathways, and kinetics

This study investigates the Hydroxylamine (HAm)-driven Cu(II)/peroxymonosulfate (PMS) system, known for promoting toxic nitro(so)phenols formation during phenol degradation. It focuses on the intricate factors affecting nitro(so)phenols formation, aiming to unravel the complex mechanisms in the transformation of phenol to nitro(so)phenols within the HAm-Cu(II)/PMS system. Findings reveal that reaction conditions significantly impact the formation of nitro(so)phenols by affecting the phenol degradation intermediate (PhO•) and HAm oxidation reactive nitrogen species (•NO, •NO2). Additionally, the levels of specific reactants and coexisting compounds also affect the pathway of nitro(so)phenols formation. At high concentrations of HAm and halogen, the •NO and halogen radicals generated may directly oxidize phenol to produce PhO•, which in turn reacts with •NO and •NO2, and thus establishing a different nitro(so)phenols formation path from that dominated by SO4∙-. The oxidation products and driving factors of HAm vary at different stages, affecting the production of nitro(so)phenols. Moreover, the presence of halogen and natural organic matter (NOM) alters the formation of nitro(so)phenols under real water conditions compared to pure water. Overall, the investigation into various influencing factors indicates that advanced oxidation process enhanced by hydroxylamine, not just limited to persulfate-related reactions, has the potential to produce nitro(so)phenols when treating phenol-containing water.

A Study on the Professional Dilemmas of Community Workers Based on Grounded TheoryA Case Study of City Y in Shandong Province, China

To explore the manifestations and formation mechanisms of the professional dilemmas faced by community workers, this study is based on Constructivist Grounded Theory and employs methods such as interviews and literature analysis to investigate the connotation and structure of these professional dilemmas. The study finds that they encompass four dimensions: interpersonal relationships, job burnout, future development, and psychological barriers. It proposes a model of the formation path of professional dilemmas for Chinese community workers, emphasizing that institutional regulations, social support and understanding, as well as the individual role positioning and professional cognition of community workers, influence the formation of their professional dilemmas. Based on this, the study discusses recommendations such as the government promoting the construction of institutional systems, the community atmosphere strengthening humanistic care, community organization construction focusing on professionalism, and society enhancing external recognition. The research results have expanded new areas in the study of community workers' professional dilemmas and laid an important foundation for an in-depth analysis of the professional dilemmas of community workers under a multidimensional social system including government policies and community resources.

Multiple Pathways in the Triplet States Population for a Naphthalenediimide-C60 Dyad.

The link of an antenna dye with an electron spin converter, in this case naphthalenediimide and C60, produces a system with a rich photophysics including the detection of more than one triplet state on the long timescale (tens of μs). Beside the use of optical spectroscopies in the ns and in the fs time scale, we used time-resolved Electron Paramagnetic Resonance (TREPR) to study the system evolution following photoexcitation. TREPR keeps track of the formation path of the triplet states through specific spin polarization patterns observed in the spectra. The flexibility of the linker and solvent polarity play a role in favouring either electron transfer or energy transfer processes.

Multiscale investigation on the formation path of the apatite phase in bioactive glasses

Mesoporous bioactive glasses (MBGs) have been reported as promising biomaterials to stimulate and promote the growth of bones. When exposed to Simulated Body Fluid (SBF), MBGs develop an apatite phase called carbonate hydroxyapatite (H(C)A) on their surfaces that closely mimics the mineral phase of bones. In order to gain deeper insights into the key stages of the surface reactions of two different types of MBGs (58S and 70S30C) soaked in SBF, we have used high energy total X-ray scattering coupled to Pair Distribution Function (PDF) analysis, along with Raman spectroscopy and scanning electron microscopy. This type of coupled analytical approach can ultimately help to unravel the details of the reaction kinetics in the complex calcium phosphate environment around the BGs surfaces. The data obtained in our in-vitro study point to the formation of other intermediate phases like amorphous calcium phosphate (ACP) and calcite (CC), that transform after a specific time into H(C)A depending on the composition of the MBGs, their surface properties and their interaction times with SBF.

Numerical study on gas reaction path of InN-MOVPE with three typical reactors

This study investigates the controversies about the gas-phase reaction path in the InN MOVPE process. Numerical modeling of the reaction-transport processes in three typical reactors was conducted for main reaction paths. By comparisons of the molar concentrations of the major In-containing species, it was determined that the different approaches of the gas mixing and heating led to three distinct reaction paths. When the non-premixed gas precursors are heated very fast upon entering the reactor, the adduct/amide formation path predominates and the pyrolysis path is negligible (Path 1). When the precursors are mixed at room temperature and heated gradually, the adduct TMIn:NH3 dissociates back into TMIn, with the pyrolysis path dominating. However, the formation of amides DMInNH2 intensifies the generation of nanoparticles (Path 2). When mixing occurs at warm temperature and heated fast, both the pyrolysis and adduct paths co-exist, but their effects are different (path 3). In the CCS reactor the dominant reaction path will be Path 1, while in the vertical reactor with a greater height, Path 2 is predominant. In the pre-mixed horizontal reactor, Path 3 is dominant, the pyrolysis path forms a competition with the adduct path near the substrate, and the adduct path dominating at the top of the reactor.

Multi-UAV Formation Path Planning Based on Compensation Look-Ahead Algorithm

Multi-UAV Formation Path Planning Based on Compensation Look-Ahead Algorithm

A Type Ia Supernova near a Globular Cluster in the Early-type Galaxy NGC 5353

No progenitor of a Type Ia supernova (SN Ia) is known, but in old-population early-type galaxies, one may find SNe Ia associated with globular clusters, yielding a population age and metallicity. It also provides insight into the formation path and the SN enhancement rate in globular clusters. We sought to find such associations and identified SN 2019ein to be within the ground-based optical positional uncertainty of a globular cluster candidate within the early-type galaxy NGC 5353 at D ≈ 30 Mpc. We reduced the positional uncertainties by obtaining Hubble Space Telescope images with the Advanced Camera for Surveys, using filters F475W and F814W obtained in 2020 June. We find that the globular cluster candidate has a magnitude, color, and angular extent that are consistent with it being a typical globular cluster. The separation between the globular cluster and SN 2019ein is 0.″43, or 59 pc in projection. The chance occurrence with a random globular cluster is ≈3%, favoring but not proving an association. If the SN progenitor originated in the globular cluster, one scenario is that SN 2019ein was previously a double-degenerate white dwarf binary that was dynamically ejected from the globular cluster and exploded within 10 Myr; models do not predict this to be common. Another, but less likely scenario is where the progenitor remained bound to the globular cluster, allowing the double-degenerate binary to inspiral on a much longer timescale before producing an SN.

Numerical study on soot formation in ammonia/ethylene laminar counterflow diffusion flame

The ammonia addition can significantly inhibit soot formation in hydrocarbon fuel flames. However, due to the complexity of the interaction between nitrogen and hydrocarbon, the inhibiting effect of NH3 addition on soot formation has not been fully understood yet. In this study, a mechanism is constructed through mechanism comparison, reduction, and merging. The constructed mechanism includes ammonia, polycyclic aromatic hydrocarbons (PAHs), and nitrogen-containing aromatic compounds (NACs) sub-chemistry. Then the constructed mechanism is coupled with a soot model to conduct a series of simulations of ammonia/ethylene laminar counterflow flames with various ammonia doping ratios. The results show that the constructed model can reproduce the suppression effect of ammonia addition on soot formation well. To explain the chemical inhibiting effect, the rate of production (ROP) and reaction pathway are analyzed. It can be concluded that the main formation pathway of benzene is C2H4 → C2H3 → C2H2 → C3H3 → A1. The decomposition of ammonia consumes H radical which is necessary for the conversion of C2H4 to C2H3, leading to a decrease in the reaction rates along the benzene formation pathway. Moreover, the N-containing species react with the small hydrocarbon molecules/radicals to form hydrogen cyanide (HCN), in which the reaction between C2H2 and N radical is the largest contributor. Compared to the reactions between C1-C2 species and nitrogen-containing species, the reactions between C3 species and nitrogen-containing species contribute less to the chemical effect of NH3 addition. All these reactions reduce the carbon flux of the benzene formation path. In addition, the impact of reactions between HCN and aromatic hydrocarbons which produce NACs is also investigated. The reactions of HCN addition to benzene and naphthalene compete with the C2H2 addition reactions, resulting in a slightly enhanced inhibiting effect of ammonia addition on soot formation.