Theoretical Phase Research Articles

Solid-State Reactions for the Storage of Thermal Energy.

In this paper, the use of solid-state reactions for the storing of thermal energy at high temperature is proposed. The candidate reactions are eutectoid- and peritectoid-type transitions where all the components (reactants and reaction products) are in the solid state. To the best of our knowledge, these classes of reactions have not been considered so far for application in thermal energy storage. This study includes the theoretical investigation, based on the Calphad method, of binary metals and salts systems that allowed to determine the thermodynamic properties of interest such as the enthalpy, the free energy, the temperature of transition, the volume expansion and the heat capacity, giving guidelines for the selection of the most promising materials in view of their use for thermal energy storage applications. The theoretical investigation carried out allowed the selection of several promising candidates, in a wide range of temperatures (300–800 °C). Moreover, the preliminary experimental study and results of the binary Mn-Ni metallic system are reported. This system showed a complex reacting behavior with several discrepancies between the theoretical phase diagram and the experimental results regarding the type of reaction, the transition temperatures and enthalpies and the final products. The discrepancies observed could be due both to the synthesis method applied and to the high sensitivity of the material leading to partial or total oxidation upon heating even if in presence of small amount of oxygen (at the ppm level).

Phenyl substituted ureas: Evaluation of thermochemical data with complementary experimental and computational methods

Standard molar enthalpies of formation of 1-phenyl-3-isopropyl-urea and 1-phenyl-3-tert-butyl-urea were derived from results of high-precision combustion calorimetry. Standard molar enthalpies of sublimation of these compounds and of phenyl-urea were derived from their vapour pressure – temperature dependences measured by the transpiration method. Thermal behaviour of phenyl substituted ureas was studied by DSC. Thermochemical data on phenyl-substituted ureas available in the literature were collected, evaluated, and combined with our own experimental results. We have evaluated and recommended for further thermochemical calculations a set of sublimation, vaporization, fusion and formation enthalpies for the phenyl-substituted ureas at 298.15 K. A computational procedure was developed to support the experimental gas-phase enthalpies of formation. The theoretical gas phase molar enthalpies of formation of the phenyl-substituted ureas calculated by the high-level quantum-chemical G3MP2 method were in a good agreement with the recommended experimental data. General regularities in energetics due to introduction of phenyl substituent in the alkyl-substituted ureas have been revealed and used for validation of the experimental and theoretical data. Additivity methods were developed to estimate the thermochemical properties of organic compounds containing the carbamide moiety.

Human competences for sustainable strategic management: evidence from Brazil

PurposeThe purpose of this paper is to identify how human competences are associated with sustainable strategic management (SSM) within organisations.Design/methodology/approachThis is a qualitative study in two phases: first, a theoretical phase is developed, resulting in a proposal for the role of human competences in organisational sustainability; second, an empirical phase including instrumental case studies of two large, sustainability-oriented Brazilian companies. Data were obtained from interviews and companies’ reports. The authors used Atlas.ti software to perform the thematic content analysis.FindingsDespite the importance of human competences in SSM, the authors find evidence that this concept has not been developed, even for companies with a consolidated position in sustainability. Human competences are a requirement for effective SSM.Research limitations/implicationsCoexisting elements within an organisation, often referred to as elements of organisational and human behaviour, can influence the dynamics of the expected interrelationships between human competences and sustainability management, in addition to the influencing factors presented in this study.Originality/valueIn general, studies advocate that the relationships among organisational competences, human competences and organisational strategies must be aligned and reinforced. Nevertheless, these relationships are not that solid as they should be as stated in both the literature and the conventional discourse of practitioners.

Cultural sensitivity in paediatric nursing care: a concept analysis using the Hybrid method.

Cultural sensitivity is a core concept to establish awareness and knowledge about various ethnicities, cultures, genders and additional diversity characteristics to understand individual's requests and respond appropriately to them. A need for further development of the concept is warranted, especially in the context of paediatric nursing. The purpose of this paper was to determine the main elements of cultural sensitivity in the context of paediatric nursing in Iran. The Hybrid method was implemented consisting of three phases: theoretical, fieldwork and final analysis. In the theoretical phase, articles from 2007 to 2017 were reviewed for relevance. In the phase of fieldwork, 25 nurses and nine parents were interviewed to explore the aspects of cultural sensitivity in paediatric nursing. The interviews were transcribed, and content analysis was conducted. In the final phase, an overall analysis of the two previous phases was performed. In the theoretical phase, the following attributes were determined: cultural encounter and awareness, acceptance of cultural diversity and designing programmes in accordance with family culture. The fieldwork phase explored three themes of intercultural encounters, intercultural communication and adapting the care plan with family culture. The final synthesis yielded that sensitivity to family requests and beliefs, effective intercultural communication and integration of family culture with the care plan are the main elements of cultural sensitivity in Iranian paediatric nursing. With a deeper understanding of the term cultural sensitivity, nurses will have a foundation to improve paediatric nursing care and align the care plan with the patient's culture to provide trust, child/parent participation, secure care, effective communication and satisfaction. Since the concepts are the building blocks that underpin theory, the present concepts identified can help to serve as the foundation for the development of a theoretical model.

Model for Calculating Cost of Laundry Services by Considering Environmental Impacts and Costs

This research aims at developing a model for calculating cost of laundry services performed by small-scale laundry businesses which incorporates environmental impact and costs into the model. The activity-based costing method is used to assign indirect costs to the cost object. This research is a continuation of the previous research conducted by the authors. Since environmental impacts and costs are considered, there will be changes in the resources and activity consumed, compared to the original model. The authors identified several environmental costs, such as eco-detergent and plastic, government fines, loss of customers and environmental costs borne by wider society. In analyzing the environmental costs, EPA classification is used. The suggested model is still in the theoretical phase, as some environmental costs arising from laundry business activities are difficult to measure. Some recommendations to laundry businesses and government are provided.

Academic Motivation in Nursing Students: A Hybrid Concept Analysis.

Background:Taking into account the breadth of the concept of motivation and its importance for nursing students, it is imperative to clarify the concept of academic motivation. This study is an attempt to analyze the concept of academic motivation in nursing students.Materials and Methods:The study was carried out in 2018 as a combined literature review and qualitative research. Hybrid concept analysis model was employed to clarify the concept at three phases. At theoretical phase, articles indexed in credential databases were searched using keywords “academic motivation” and “nursing.” Totally, 30 articles were analyzed. At fieldwork phase, 12 nursing students were interviewed. At conclusive phase, the findings of the two earlier phases were analyzed. After determining the attributes, antecedents, and consequences, a final definition of academic motivation in nursing student was introduced.Results:Academic motivation has six main attributes including “being an internal process,” “purpose oriented,” “variable,” “unique,” “driving force of educational performance,” and “facilitator of learning and educational achievement.” In addition, antecedents and consequences of academic motivation in the nursing students were revealed and a general definition of the concept was codified.Conclusions:Academic motivation of nursing students is a broad and multi-dimensional concept that is affected by various personal, family, social, educational, and professional factors. Moreover, it is a factor in achieving academic success, better quality of learning, creativity, academic satisfaction, reduction of anxiety, continuing education, and training competent nurses.

Care needs in the phase I of cardiac rehabilitation: A hybrid concept analysis

Background: Care quality improvement necessitates the identification and fulfillment of patients' care needs. Yet, there is no comprehensive information about the care needs of patients with coronary artery disease (CAD). Objectives: The objective of this study was to analyze the concept of care needs in the Phase I of cardiac rehabilitation (CR). Methods: This concept analysis was conducted using the three-phase hybrid model. In the first (theoretical) phase, the attributes of care needs were identified through a literature review. In the second (fieldwork) phase, data were collected through semi-structured interviews and were analyzed through directed content analysis to determine the attributes of care needs based on the sociocultural context of Iran. Six patients, five nurses, and one surgeon were purposively recruited from two university hospitals and one private hospital in Ahvaz, Iran. In the third (final analytic) phase, the results of the first and the second phases were integrated, and the final attributes of the concept were identified. Results: The first phase revealed that the concept of care needs has three main attributes, namely physical, psychological, and social care needs. Besides confirming these three attributes, the second phase showed that the concept also has another attribute, that is, spiritual care needs. Conclusion: The concept of care needs in the Phase I of CR includes the four main dimensions of physical, psychological, social, and spiritual care needs. The findings of this study provide useful information for the careful assessment of care needs among patients with CAD.

The gravity model of trade

Purpose. The purpose of this study is to trace the theoretical developments of the gravity model of trade. The key question is: what are the dominant features of the development of the gravity trade model? Methodology. This research is conducted by employing a number of methods that include the historical, descriptive and analytical methods. The main contribution of this paper is to trace the historical and theoretical development phases of the gravity model. Findings. This study is a novel attempt in terms of the identification of the four distinctive phases of the development of the gravity model. This work would, therefore, expand the existing literature on the gravity model. We argue that the development of the gravity model is the outcome of many research efforts. A large body of literature has given the model a solid theoretical foundation. But there is no consensus about the proper econometric estimation methods of the model. The gravity model is significant both historically and analytically. It is a useful tool for the analysis of international trade. It has become a popular research device used by the researchers and policy makers around the world. The gravity is regarded as one of the most successful models in the literature of international economics. Originality. The original contributions of this paper lie in streamlining the consistent historical development of the gravity model over a longer period of time-frame, ranging from 1885 to 2018. Limitations and Implications. This work is theoretical aspects of the trade gravity model. Future researchers could overcome the limitations by combining the theoretical and empirical studies in a paper. This paper can help the future researchers in dealing with the broad body of literature of gravity model. Acknowledement. This study was supported by the National Natural Science Foundation of China (grants No.71673223 & 71473197), and a PhD scholarship from the China Scholarship Council (CSC). The first author would like to thank the CSC for the financial support. He also acknowledges the invaluable research advice and guidance received from Dr. Yoto V. Yotov, professor at the School of Economics of the Lebow College of Business at Drexel University, Philadelphia, USA. The authors are highly grateful to the anonymous reviewers, managing editor, and the editor-in chief for their kind help and critical comments on the earlier drafts of the paper. However, the authors are responsible for the contents and limitations of the study. They declared no conflict of interests.

Concept Analysis of Health Literacy for Patients with Cardiovascular Disease using Hybrid Model

Purpose: The purpose of this study is to provide a clear definition of the health literacy for patients with cardiovascular disease by analyzing the dimensions and properties using Hybrid concept analysis. Methods: The concept of health literacy of patients with cardiovascular disease was analyzed according to the cyclic process of theoretical phase-field work phase-final analysis phase presented in the Hybrid model. We reviewed 26 literatures and conducted in-depth interviews with 13 patients with cardiovascular disease. Results: The concept of health literacy in cardiovascular patients is derived from two dimensions and five attributes. Literacy skills, health information search ability and health information utilization skills were derived as attributes in the individual functional dimension, while active communication with the medical team and utilization of health information support resources were derived at the interrelational dimension. It is defined as the individualized and integrated ability of an individual to explore and utilize the various health information needed to make appropriate health decisions during the chronic course after diagnosis of cardiovascular disease, to communicate proactively with medical staffs and to utilize support resources. Conclusion: This study will contribute to the development and related research of health literacy measurement tools that can be used in cardiovascular nursing practice based on the attributes and indicators of health literacy for patients with cardiovascular disease.

Space Design for Thermal Comfort and Energy Efficiency in Summer

Space Design for Thermal Comfort and Energy Efficiency in Summer

In Processing Fault Detection of Machinery Based on Instantaneous Phase Signal

The instantaneous phase signal contains abundant information about the health state of machineries, which plays an important role in fault detection of machineries, rotor dynamic balance, transmission error of Rotate Vector reducer, etc. Traditional methods use signal processing methods based on encoders, EMD and Hilbert transforms or fractional delay filters to extract instantaneous phase information indirectly. These traditional methods are state-of-art, however those algorithms are slightly complicated and time-consuming, which is not conducive to online prognostics and health management to some extent. In fact, high precision and high reliability sensor technology can effectively reduce the complexity of subsequent signal processing. In this paper, an instantaneous phase direct detection technique based on eccentric demodulation principle is proposed. The method is derived from the kinematics between the cam and the pushrod. The laser displacement sensor is used to replace the pushrod to realize non-contact measurement. The instantaneous phase is modulation by the cam, and the proposed method can realize the obtain of the theoretical phase infinite resolution, which reaches 16,000-line resolution. Compared with the traditional encoder and other inspection technologies, the proposed method is also suitable for the measurement of broadband shifting and reciprocating motion. By means of simple signal processing methods, this paper realizes the fault diagnosis of the rolling bearing with typical defectives, and realizes the extraction and identification of the fault signal of the reciprocating compressor. Experimental results proved that the proposed inspection technology can serve as an effective technology for mechanical fault diagnosis.

Novel combined measurement system to characterize film structures by spectral interferometry and ellipsometry.

We propose a novel measurement system to simultaneously measure surface and thickness profiles of thin film structures, which cannot be realized in typical measurement techniques. This measurement is accomplished by combining spectral interferometry and ellipsometry. These two distinct measurement techniques are involved in a single system by the abnormal optical configuration. Further, the measurement results are complementary in order to characterize film structures. Film thickness profiles are measured by spectroscopic imaging ellipsometry and surface profiles are obtained from the spectral phase by spectrally resolved interferometry. This method eliminates the theoretical spectral phase by film thicknesses. The proposed system can determine the dimensional film structures at once, even though they have multi-layered films, substrate textures, and even thin film layers. In the experiments, each measurement principle was fundamentally verified with standard specimens. Further, a 4-layered film specimen was measured in order to reconstruct its 3D film structure. As the result, the repeatability of spectroscopic imaging ellipsometry was less than 1 nm and that of spectrally resolved interferometry was a few nanometers, which dominantly affected the performance of the whole system. Several issues for improving accuracy and precision of the proposed system are also discussed in this paper.

Microstructural Characterization of Equiatomic CrFeNbNiV Alloy

This paper presents the results of an experimental study to investigate the structural and microchemical characteristics of an equiatomic CrFeNbNiV alloy. XRD analysis of CrFeNbNiV alloy, revealed a predominant NbCrNi type HCP Laves phase conjoined with two minor tetragonal and BCC phases. Detailed microstructural investigations using electron microscopy techniques also substantiated the presence of the above mentioned phases. The structure of Laves phase in this alloy is determined ab initio for the first time using Precession Electron Diffraction technique which was in agreement with the Rietveld analysis of XRD pattern. The formation of intermetallic Laves phase was understood based on theoretical phase stability and average d- orbital energy level $$\overline{\text{Md}}$$ value calculations. The alloy in the ‘as cast’ condition exhibited a very high value of hardness (~ 1500 Hv). No change in the microstructure and hardness was observed on annealing at high temperatures even up to 1373 K (1100 °C).

Systemic Modeling of Camargo Guarnieri’s Ponteio n. 8

Dividido em três partes, este artigo demonstra o processo de Modelagem Sistêmica do Ponteio n.8, de Camargo Guarnieri, como base para a composição da obra para violino solo de Marcel Castro-Lima, intitulada Preludio. Na primeira parte, a Modelagem Sistêmica é apresentada com seus pressupostos teóricos e fases metodológicas. Em seguida propomos a possibilidade de uma Análise Schenkeriana na qual a Polarização Acústica de Costère oferece uma solução para o problema da hierarquia, decorrente do ambiente pós-tonal da peça analisada. O processo analítco é descrito em detalhes. Por último, demonstramos o processo de Planejamento Composicional de Preludio, a partir do Sistema Composicional resultante da modelagem do Ponteio n. 8.

Theoretical Phase Resolved Ammonia–Ammonium Nitrogen Equilibrium Isotope Exchange Fractionations: Applications for Tracking Atmospheric Ammonia Gas-to-Particle Conversion

Nitrogen (N) equilibrium isotope fractionation (15α) involving gaseous, dissolved, and solid phases of ammonia (NH3) and ammonium (NH4+) (e.g., NH3(g)–NH3(aq)–NH4+(aq)–NH4+(s)) represents a fundamental chemical process that has important implications for understanding the environmental dynamics involving NHx (NH3 + NH4+). However, recent literature disagrees with early experimental results from Urey and co-workers, suggesting the need for an update on theoretical estimates. Here, we have calculated theoretical 15α values for NH4+(g)/NH3(g), NH3(aq)/NH3(g), NH4+(aq)/NH3(g), NH4+(aq)/NH3(aq), and NH4+(s)/NH3(g) using HF/6-31G(d) and B3LYP/6-31G(d) levels of theory. Overall, our theoretical calculated values matched experimental data reported by Urey and co-workers, with best agreement obtained at the HF/6-31G(d) level of theory with solvent effect accounted for using water cluster calculations. Our calculated results have important implications for tracing NH3 gas-to-particle phase conversions that may have...

A new higher-order Landau–Ginzburg–Devonshire theory for KNbO3 crystal

ABSTRACTA Landau-Ginzburg-Devonshire(LGD) theory based on a structurally stable 8th-order potential with three varying expansion coefficients (a1, a11 and a2) was proposed for phenomenological description for KNbO3. The phase diagrams in the space of phenomenological parameters of the LGD potential model with co-dimension (Codim) of 2 and 3, invariant under the cubic point group m3m, were constructed. The values of the phenomenological coefficients of the potential model were determined by fitting experimental data. The theoretical pressure-temperature phase diagram which can explain the experimentally observed cubic-tetragonal-orthorhombic triple point and cubic-orthorhombic phase transition was constructed. Temperature dependences of spontaneous strain, lattice constants, dielectric constants and spontaneous polarization calculated with this potential model were in good agreement with the experimental data. Furthermore, the influence of the hydrostatic pressure on the dielectric constant (ε33) in the vicinity of the triple point and the dependence of piezoelectric coefficients on the applied electric field were predicted.

Effect of the microstructure of graphitic boron nitride on the kinetics of the formation of boron nitride high-pressure phases

Three types of hexagonal boron nitride (h-BN) with graphitic crystal structure having different microstructures were subjected to high pressures (HP) and high temperatures (HT), and the kinetics of the phase transitions to the sp3-hybridized phases (w-BN, c-BN) was studied using in situ synchrotron diffraction. The analysis of the phase transformation kinetics revealed the transformation paths and activation energies Ea of the transformation of h-BN to the high-pressure forms of BN for different microstructures of h-BN. Defect-poor h-BN transforms to metastable wurtzitic BN (w-BN) with Ea ≈ 0.3 eV/at. Defect-rich forms of h-BN transform directly to c-BN, but with a higher activation energy. It was observed that the turbostratic disorder in h-BN retards the phase transition as compared to h-BN containing corrugated basal planes and a low degree of turbostracity. The experimental results are discussed in view of the microstructure changes during the HP/HT treatment and compared to available theoretical phase transition models.

Theoretical investigation on vanadium dinitrides from first-principles calculations

Motivated by successful synthesis of the first early transition metal dinitride TiN2 under high pressure, the possible crystal structures of another family member vanadium dinitride (VN2) have been systematically explored up to 300 GPa by using a well-developed CALYPSO (Crystal structure Analysis by Particle Swarm Optimization) method for crystal structural prediction. Three theoretical phases with P63/mmc, Cmc21, and I4/mcm space group have been determined at different pressures. And their dynamical and mechanical stabilities have been confirmed by the phonon dispersion and elastic constants calculations. Among three predicted phase, the tetragonal I4/mcm-VN2 exhibits highly improved Young's, bulk and shear moduli relative to the traditional fcc-VN, indicating its potential mechanical applications. In addition, the elastic anisotropy of each phase was fully investigated by the dependence of Young's modulus on the crystal orientation. To further study the mechanical property, the ideal tensile, shear, and compressive strengths are calculated. Our results imply the tetragonal phase of VN2 is not an intrinsic superhard material. The electronic structures are analyzed to study the chemical bonding nature so as to confirm the driving force of the enhancement of the mechanical property.

Lattice Boltzmann simulation of mixtures with multicomponent van der Waals equation of state

We developed a general framework for simulating multicomponent and multiphase systems using the lattice Boltzmann framework. Despite the fact that there is no restriction on the number of components in principle, in this article we focus an application to two-component mixtures, but we also demonstrate that the algorighm works for larger numbers of components. To validate our algorithm we separately minimized this underlying free energy to generate theoretical phase diagrams for mixtures of fluids with a van der Waals-like free energy. All the theoretical phase diagrams are well recovered by our lattice Boltzmann method.

Phase sensitivity of off-axis digital holography.

In off-axis digital holography, the Fourier transform-based algorithm is commonly used for signal processing. Here, we derive the theoretical phase sensitivity of this algorithm, which can be calculated from a single 2D hologram. This algorithm sensitivity represents the best achievable sensitivity of a system using this algorithm. Our derivation treats the signal in its most general form, considering non-uniform illumination and the effect of sideband filtering. As a result, phase sensitivity varies spatially, determined by local signal-to-noise ratio. Sensitivity expressions for both shot noise and uniform noise models are given. These results are validated with simulations and experiments. Significantly, this theoretical sensitivity can serve as a baseline metric for assessing performance of a phase-imaging system, such as experimental sensitivity and hardware stability, which are critical for high-sensitivity quantitative phase imaging. In addition, the results are equally applicable to other interferometric techniques with similar interferogram patterns and signal processing algorithms.