Relative Phase Research Articles

Integrating the SDGs into the agenda of an Argentine university

PurposeThe purpose of this study is to explore the incorporation of the sustainable development goals (SDGs) at the National University of Moreno (Universidad Nacional de Moreno, UNM, in Spanish), focusing on teaching and research activities, encountering difficulties from primary and secondary information sources, to integrate the SDGs, and contribute with actions for their incorporation into teaching and learning processes and research, in a newly established university.Design/methodology/approachTo describe the implementation of the SDGs, an empirical study was conducted using a mixed methodology for data collection. Data collected from the survey were combined with information from the UNM project database for the period 2017–2022. Non-parametric methods were used to analyse both sets of data.FindingsThis study provides an initial overview of SDG implementation at UNM, allowing the identification of constraints and challenges to scale up contributions to the SDGs at UNM, as well as the generation of relevant action lines in the interaction with university's authorities.Research limitations/implicationsConducting studies through questionnaires has limitations, similar to other cases analysed. To increase the validity of the data, prior consultations were carried out. In addition, the database of research projects was used to identify the application of the SDGs in research. However, an approximation of the current situation could be obtained.Practical implicationsParticular importance was given to the challenges encountered during the data analysis phase in relation to capacity building needs. This enabled a set of actions to be defined to bring the SDGs closer to the UNM.Originality/valueAlthough the paper used methodologies already proposed by other authors, such as survey collection, its value lies in demonstrating the possibility of using them to analyse whether the SDGs are integrated into teaching and research activities in a recently founded university, where the SDGs are integrated into its principles. The analysis also complements the survey results with information from project databases, which has not yet been analysed in the literature. Based on the results, activities are designed so that the SDGs could begin to guide teaching and research activities.

Phase Relationships and Distribution of S, Fe, Co, Ni, Re, Os, and Pt between Metal and Sulfide Melts in the Basalt–Fe–FeS–C System at 1400°C and 4 GPa

Phase Relationships and Distribution of S, Fe, Co, Ni, Re, Os, and Pt between Metal and Sulfide Melts in the Basalt–Fe–FeS–C System at 1400°C and 4 GPa

Respiratory sinus arrhythmia: physiological mechanisms and relationship with systemic blood pressure fluctuations

Respiratory sinus arrhythmia (RSA) reflects the functioning of the nervous heart control, predominantly of a parasympathetic nature. The study of RSA mechanisms helps to reveal the physiological patterns of regulation of cardiac activity, and the development of new approaches to its assessment is an urgent medical task. This review will examine experimental approaches that have contributed to the development of modern ideas about autonomic nervous system role in the formation of RSA, as well as the connection between RSA and frequency-matched fluctuations in systemic blood pressure. In addition, we will consider new data on the phase relationships of fluctuations in heart rate and blood pressure in the frequency range of respiratory waves, obtained using wavelet analysis of these physiological signals.

Polarization-entangled photons from a whispering gallery resonator

Crystalline whispering gallery mode resonators (WGMRs) have been shown to facilitate versatile sources of quantum states that can efficiently interact with atomic systems. These features make WGMRs an efficient platform for quantum information processing. Here, we experimentally show that it is possible to generate polarization entanglement from WGMRs by using an interferometric scheme. Our scheme gives us the flexibility to control the phase of the generated entangled state by changing the relative phase of the interferometer. The S value of Clauser–Horne–Shimony–Holt’s inequality in the system is 2.45 ± 0.07, which violates the inequality by more than six standard deviations.

Sino-Africa Relations Post-Covid-19: Issues for Consideration

Sino-Africa relations have been periodised into three phases. The first phase (1950s–1970s) includes the establishment of the People’s Republic of China (PRC) in 1949 and the decolonisation of African states. The second phase (1971–1990s) includes the drift of Sino-Soviet relations, the admission of China into the United Nations Security Council (UNSC), as well as the end of the Cold War. The third phase (2000s–2020) covers the inclusion of China into the World Trade Organisation (WTO) in 2001, as well as the establishment of the Forum on China-Africa Cooperation (FOCAC) in 2010. This article considers the fourth phase of Sino-Africa relations, argued to have begun in 2020 post-Covid-19, taking place at a time of de-globalisation, the ongoing Russia-Ukraine war and the US-China trade war. We assert that the latter changing global dynamics must be considered in making sense of Sino-Africa relations today. The article argues that despite such a changing global political order, there have been continuities and changes in China’s relations with the African continent. This is evident in the tightening of its relations with Africa, irrespective of ongoing dynamics in global affairs. Despite concerns about the USA’s reprioritisation of Africa, the establishment of the African Continental Free Trade Area (AfCFTA), China’s Belt and Road Initiative (BRI), vaccine diplomacy, and China and African States’ “neutrality” stance on various ongoing conflicts, it is safe to say that Sino-Africa relations will triumph even in this new phase.

Characterizing strong-field tunneling ionization with a phase-dependent THz polarization spectrum

The terahertz radiation emitted by asymmetrically ionized wavepackets in two-color strong-field tunneling ionization is essential for detecting the system's associated electron dynamics and structural properties. We propose to characterize and control tunneling ionization using a phase-dependent terahertz polarization (PTP) spectrum, analyzed through a combination of the classical trajectory Monte Carlo method, an analytical model based on the virial theorem, and the rigorous solution of the time-dependent Schrödinger equation as a benchmark. Our results demonstrate that the PTP spectrum offers a high-precision measure of the Coulomb effect through the relative phase of the two-color laser. Comparisons of PTP results calculated using different methods suggest how the electron can be manipulated by controlling the relative phase and laser intensity. In particular, the PTP spectrum can be used to calibrate the relative phase and provides a convenient and robust reconstruction of the time-averaging of tunneling positions with high precision using the analytical model. These insights reveal that the PTP spectrum as a whole can be a new and useful tool for the all-optical characterization of ultrafast atomic and molecular ionization.

A contactless in situ EFISH method for measuring electrostatic potential profile of semiconductor/electrolyte junctions.

In photoelectrochemical cells, promising devices for directly converting solar energy into storable chemical fuels, the spatial variation of the electrostatic potential across the semiconductor-electrolyte junction is the key parameter that determines the cell performance. In principle, electric field induced second harmonic generation (EFISH) provides a contactless in situ spectroscopic tool to measure the spatial variation of electrostatic potential. However, the total second harmonic generation (SHG) signal contains the contributions of the EFISH signals of semiconductor space charge layer and the electric double layer, in addition to the SHG signal of the electrode surface. The interference of these complex quantities hinders their analysis. In this work, to understand and deconvolute their contributions to the total SHG signals, bias-dependent SHG measurements are performed on the rutile TiO2(100)-electrolyte junction as a function of light polarization and crystal azimuthal angle (angle of the incident plane relative to the crystal [001] axis). A quadratic response between SHG intensity and the applied potential is observed in both the accumulation and depletion regions of TiO2. The relative phase difference and amplitude ratio are extracted at selected azimuthal angles and light polarizations. At 0° azimuthal angle and s-in-p-out polarization, the SHG intensity minimum has the best match with the TiO2 flatband potential due to the orthogonal relative phase difference between bias-dependent and bias-independent SHG terms. We further measure the pH-dependent flatband potential and probe the photovoltage under open circuit conditions using the EFISH technique, demonstrating the capability of this contactless method for measuring electrostatic potential at semiconductor-electrolyte junctions.

Influence of SnWO4, SnW3O9, and WO3 Phases in Tin Tungstate Films on Photoelectrochemical Water Oxidation.

An essential step toward enabling the production of renewable and cost-efficient fuels is an improved understanding of the performance of energy conversion materials. In recent years, there has been growing interest in ternary metal oxides. Particularly, α-SnWO4 exhibited promising properties for application to photoelectrochemical (PEC) water splitting. However, the number of corresponding studies remains limited, and a deeper understanding of the physical and chemical processes in α-SnWO4 is necessary. To date, charge-carrier generation, separation, and transfer have not been exhaustively studied for SnWO4-based photoelectrodes. All of these processes depend on the phase composition, not only α-SnWO4 but also on the related phases SnW3O9 and WO3, as well as on their spatial distributions resulting from the coating synthesis. In the present work, these processes in different phases of tin tungstate films were investigated by transient surface photovoltage (TSPV) spectroscopy to complement the analysis of the applicability of α-SnWO4 thin films for practical PEC oxygen evolution. Pure α-SnWO4 films exhibit higher photoactivities than those of films containing secondary SnW3O9 and WO3 phases due to the higher recombination of charge carriers when these phases are present.

Effect of relative phase of loose tie rods on nonlinear dynamic behavior of rod-fastening rotor-bearing-seal system

Loosening of multiple tie rods in a circumferential rod-fastening rotor caused by thermal deformation and centrifugal loads is very common in engineering. The relative position of loose tie rods in the circumferential direction will also have an important impact on rotor dynamics. The relevant research has not been done yet. In this paper, a contact model of the rough machined surface is firstly established by combining the probability functions describing rough surfaces and fractal contact theory of asperities, then the contact stiffness model between disks is established based on the contact model. Finally, the dynamic model of the circumferential rod-fastening rotor-bearing-seal system is established and solved. The effect of relative phase of loose tie rods on the nonlinear dynamic characteristics of rod-fastening rotor-bearing-sealing system is studied. It can be concluded that relative phase of the loose tie rod has an important influence on the frequency, bifurcation, and periodic motion of the rotor system. At lower speed, the anisotropy of contact stiffness caused by loose tie rods has little effect on the rotor trajectory, while the generalized bending moment has a greater influence on dynamics of the system. At higher speed, the anisotropy of contact stiffness has a great influence on the axis rail of the rod-fastening rotor.

Tunable pattern recognition of optical QPSK data using optical correlation and direct detection.

Performing pattern recognition via correlation in the optical domain has potential advantages, including: (i) high-speed operation at the line rate and (ii) tunability and scalability by operating on the optical wave properties. Such pattern recognition might be performed on quadrature-phase-shift-keying (QPSK) data transmitted over an optical network, which generally requires using coherent detection to distinguish the phase levels of the correlator output. To enable simpler detection, we combine optical correlation with optical biasing to experimentally demonstrate tunable and scalable QPSK pattern recognition using direct detection. The pattern is applied by adjusting the relative phases of the local pumps. Delayed QPSK signals, a coherent bias tone, and local pumps undergo nonlinear wave-mixing in a periodically poled lithium niobate (PPLN) waveguide to perform optical correlation and biasing. The biased correlator output is captured using direct detection, where the highest power level corresponds only to the pattern. Multiple QPSK pattern recognitions are achieved error-free over 3072 symbols using power thresholding values of (i) 0.78 at a 5-Gbaud rate and 0.73 at a 10-Gbaud rate for 2-symbol pattern recognition and (ii) 0.81 at a 5-Gbaud rate and 0.79 at a 10-Gbaud rate for 3-symbol pattern recognition.

Identification of flame transfer function and mechanism analysis of the influence of boundary impedance characteristics on thermoacoustic instability

Thermoacoustic instability is a common problem in the operation of modern gas turbines. The prediction of thermoacoustic instability and the clarification of its mechanism are the research focus and difficulty in the gas turbine industry. As a response function of flame to acoustic disturbance, flame transfer function is a key parameter in the study of thermoacoustic instability. In this paper, based on the scaled adaptive simulation (SAS) model combined with the eddy dissipation concept (EDC) combustion model, the time-domain flow field data are processed by the system identification method, and the results of flame transfer function extraction are in good agreement with the experimental values. Then, the detailed derivation process of the low-order thermoacoustic network model (LOTAN) is given to capture the behavior characteristics of the acoustic wave in the thermoacoustic system. On this basis, the effects of acoustic boundary conditions and hysteresis time on the thermoacoustic instability of the combustion system are analyzed, and the relationship between the mode shape, pressure, vibration velocity phase, and thermoacoustic instability is explored. It is found that the phase relationship between pressure and vibration mode can be used to determine the thermoacoustic instability of the system. This is of great practical significance for determining the thermoacoustic instability of the system and clarifying the internal mechanism of its generation and provides theoretical support for the subsequent thermoacoustic instability control.

Tropical Cyclone Boundary Layer Asymmetries in a Tilt-Following Perspective

Abstract Previous observations and modeling studies showed that tropical cyclones (TCs) in a sheared environment develop an asymmetric boundary layer (BL). While the relationship between the BL asymmetries and environmental shear has been demonstrated, the exact cause of these BL asymmetries and the phase relationship between them are less well understood. In this study, we examine the dynamical processes leading to the asymmetric structure of the TC BL in a sheared environment using idealized, convection-permitting model simulations. Our results show that the emergence of the BL asymmetries is closely linked to the TC vortex tilt and rainband processes. Specifically, stratiform diabatic processes in the downtilt-left region result in midlevel descending inflow, which brings midtropospheric, low-θE air toward the BL and forms a surface cold pool in the downtilt-left quadrant. This descending inflow also advects high absolute angular momentum inward, redistributing the vertical vorticity and causing a storm-scale tangential wind acceleration within the downtilt-left quadrant. As the BL low-θE air advances inward, it becomes supergradient and decelerates radially, forming BL outflow in the uptilt-left quadrant. The outflow advects positive relative vorticity uptilt, forming an elliptic BL vorticity and circulation structure. As the tilted TC vortex and the accompanying rainband precess cyclonically over time, the above sequence of events and the resultant BL asymmetries also precess cyclonically, maintaining a quasi-stationary configuration relative to the vortex tilt. These results suggest that the primary organizing factor of the boundary layer asymmetries is the tilted vortex structure and not strictly the environmental shear direction.

Supporting students to become agents of change: Introducing and evaluating the Transition Cycle approach to teaching transformative skills

Human societies are dealing with urgent and daunting societal transition challenges, such as those posed by climate change, inequality, pandemics, and digitalization. In all these cases, we know that they must fundamentally change the way they do and think about things, and urgently so, but do not know how. Uncertainty about the direction of change and resistance to change are ubiquitous. Future generations must be equipped with capabilities for dealing with these challenges. However, there is an apparent mismatch between the skills currently taught and the skills needed to address complexity, uncertainty, and resistance. Using relevant existing frameworks and experiences we created and taught a course focusing on fostering these skills. For this purpose we developed the Transition Cycle, an original educational approach in which students work on a societal transition challenge in four distinct but related phases: imagine, connect, act, and assess. In this paper, we introduce and evaluate the Transition Cycle and its underlying concepts, basic components, implementation in the course, and learning outcomes. We conclude by reviewing lessons learned and raising questions for future research and experimentation.

Systematic Experimental Evaluation of Aeroelastic Characteristics of a Highly Flexible Wing Demonstrator

This paper presents a comprehensive experimental analysis of the evolutionary modal characteristics of a highly flexible wing that exhibits bending–torsion coupling-driven instability. By implementing operational modal analysis on responses triggered by a combination of an external pulse-like stimulation and turbulence within the flow, this paper presents the airspeed-driven variations of the modal frequencies, damping ratios, and the underlying modal coupling behavior, leading to instability. This analysis is extended to varying the wing root pitch angles through which the effects of geometrical nonlinearity are exercised. Their effects are particularly noted on the hump feature of the airspeed-driven damping ratio locus of the mode responsible for instability. The decreasing critical damping ratio is shown to result in amplified turbulence-driven responses, which pose significant challenges to identification procedures by masking the visibility of other modes. Furthermore, through a novel technique used to analyze the modal coupling, the relative phase and magnitude properties of the coupled bending–torsion composition of the critical mode before and at flutter onset are evidenced experimentally. It is demonstrated that these relative participation measures provide a strong indication of the response content of the limit cycle oscillations that emerge after the flutter speed.

Phase relations in the La2O3-ZrO2-HfO2 system at 1250 °C and 1500 °C

In the present study, the phase equilibria in the ternary system La2O3-ZrO2HfO2 have been studied in the whole concentration range. In the course of the study, isothermal sections of the phase diagram of the system were constructed at temperatures of 1500 and 1250 °C. The obtained results indicate the no new phase formation in the studied system. It was found that in the La2O3-ZrO2HfO2 ternary system at temperatures of 1500 and 1250 °C, solid solutions are formed on the basis of monoclinic (M, space group P21/C) HfO2 and tetragonal (T, space group P42/nmc) modifications of ZrO2, solid solutions based on a hexagonal modification (A, space group P3m1) of La2O3, and an ordered phase with a pyrochlore-type structure of La2Zr2О7 (La2Hf2О7) (Py, space group Fd-3 m). The system studied is characterized by the formation of a continuous series of solid solutions with a pyrоchlore-type structure. A decrease in temperature from 1500 °C to 1250 °C leads to the shift of the three-phase region, containing solid solutions based on a pyrochlore-type structure of Ln2Zr2О7 (Ln2Hf2О7), monoclinic M-HfO2, and tetragonal T-ZrO2, towards the concentration area with higher ZrO2 content and also to an increase in the extent of the solid solution based on the monoclinic modification M-HfO2.

Effect of sintering temperature and holding time on structure and properties of Li1.5Ga0.5Ti1.5(PO4)3 electrolyte with fast ionic conductivity

Li1.5Ga0.5Ti1.5(PO4)3 (LGTP) is recognized as a promising solid electrolyte material for lithium ions. In this work, LGTP solid electrolyte materials were prepared under different process conditions to explore the effects of sintering temperature and holding time on relative density, phase composition, microstructure, bulk conductivity, and total conductivity. In the impedance test under frequency of 1−106 Hz, the bulk conductivity of the samples increased with increasing sintering temperature, and the total conductivity first increased and then decreased. SEM results showed that the average grain size in the ceramics was controlled by the sintering temperature, which increased from (0.54±0.01) μm to (1.21±0.01) μm when the temperature changed from 750 to 950 °C. The relative density of the ceramics increased and then decreased with increasing temperature as the porosity increased. The holding time had little effect on the grain size growth or sample density, but an extended holding time resulted in crack generation that served to reduce the conductivity of the solid electrolyte.

Stretched-exponential melting of a dynamically frozen state under imprinted phase noise in the ising chain in a transverse field

The concept of dynamical freezing is a phenomenon where a suitable set of local observables freezes under a strong periodic drive in a quantum many-body system. This happens because of the emergence of approximate but perpetual conservation laws when the drive is strong enough. In this work, we probe the resilience of dynamical freezing to random perturbations added to the relative phases between the interfering states (elements of a natural basis) in the time-evolving wave function after each drive cycle. We study this in an integrable Ising chain in a time-periodic transverse field. Our key finding is, that the imprinted phase noise melts the dynamically frozen state, but the decay is “slow”: a stretched-exponential decay rather than an exponential one. Stretched-exponential decays (also known as Kohlrausch relaxation) are usually expected in complex systems with time-scale hierarchies due to strong disorders or other inhomogeneities resulting in jamming, glassiness, or localization. Here we observe this in a simple translationally invariant system dynamically frozen under a periodic drive. Moreover, the melting here does not obliterate the entire memory of the initial state but leaves behind a steady remnant that depends on the initial conditions. This underscores the stability of dynamically frozen states.Graphical abstract

Swedish wind power expansion: Conflicting responsibilities between state and municipalities

Sweden has experienced two decades of wind power expansion and enters a broad diffusion phase. In this study the aim is to deepen the knowledge of the municipal role in this phase in relation to national wind power policy. Local public officials and politicians was interviewed in fourteen Swedish municipalities. The results show that municipal representatives experience great uncertainty about the responsibilities and incentives they have in the energy transition – responsibilities that are difficult to interpret but also difficult to realize in practice. In conclusion, unclear State policy, increased social resistance, lacking municipal capabilities, and a market-driven planning regime adds a burden of incongruous responsibility on municipalities, which risks enforcing uncertainties in the transition of the national energy system. The study brings socio-technical insight to the global expansion of renewable energy within decentralized political systems.

Study of vibration patterns and response transfer relationships in walnut tree trunks

Fruit tree trunk is the support structure of the whole tree, carrying the task of vibration transmission to all levels of branches, fruit tree trunk vibration response to the design and optimization of the vibration harvesting device to provide guiding value. In this paper, the vibration response and harvesting test was carried out for four walnut fruit trees with different morphology and size, and the vibration transmission relationship between the excitation device and the fruit tree as well as inside the fruit tree was analyzed and studied according to the acceleration response curves at each position point under different frequencies. At the same time, the theoretical vibration pattern of the fruit tree and the measured spatial three-dimensional vibration pattern were constructed, and the response transfer law between each point of the fruit tree was further analyzed in terms of the vibration pattern and direction of each position point on the tree. The results show that the excitation response acceleration is basically no attenuation inside the device, but there is some attenuation in the clamping part due to the presence of damping pads. The vibration response in the fruit tree trunk is greater in amplitude farther from the excitation point. The phase relationship between each position point is basically the same in the theoretical vibration mode and the measured vibration mode, but there is damping in the actual fruit tree, which leads to the accumulation of phase hysteresis in the transmission of excitation parameters. The actual response trajectory is a narrow ellipse, and the different position points show different rotational relationships along the ellipse trajectory due to the growth of the fruit tree.

Intermittency transition to azimuthal instability in a turbulent annular combustor

We experimentally study the transition from a state of combustion noise to azimuthal thermoacoustic instability in a laboratory-scale turbulent annular combustor. This combustor has sixteen swirl-stabilized burners to facilitate continuous and spatially distributed combustion along the annular region. Our approach involves simultaneous measurement of CH* chemiluminescence emission of the flame using two high-speed cameras and the acoustic pressure fluctuations using eight piezoelectric pressure transducers mounted on the backplane of combustor. We observe that the transition from combustion noise to azimuthal instability occurs through mode shifting, where the system switches from a longitudinal mode to an azimuthal mode as the equivalence ratio is decreased. Throughout this progression, the combustor exhibits various dynamical behaviors, including intermittency, dual-mode instability, standing azimuthal instability, and beating azimuthal instability. These dynamical states are determined from the acquired pressure signals by decomposing the acoustic pressure fluctuations into clockwise (CW) and counterclockwise (CCW) waves, enabling a reconstruction of the amplitude of acoustic pressure fluctuations, nature angle, (anti-)nodal line location, and spin ratio. The global heat release response is then examined during various dynamical states, contrasting their behavior at different non-dimensional time steps by phase-averaging the fluctuations of the heat release rate over the acoustic pressure cycle. Distinctive flame behaviors were observed based on the direction of pressure wave propagation, showcasing characteristic CCW spinning, standing, and CW spinning heat release patterns. Moreover, our examination of relative phase distributions during various dynamical states, computed by analyzing the phase of heat release rate fluctuations across all burners with respect to one burner, reveals the emergence of diverse patterns in the interaction of neighboring flames influenced by acoustic field.