An Adaptive Modeling Framework for Bearing Failure Prediction

Rolling element bearings are a common component in rotating equipment, a class of machines that is essential in a wide range of industries. Detecting and predicting bearing failures is then vital for reducing maintenance and production costs due to unplanned downtime. In previous literature, significant efforts have been devoted to building data-driven health models from historical bearing data. However, a common limitation is that these methods are typically tailored to specific failure instances and have limited ability to model bearing failures between repairs in the same system. In this paper, we propose a multi-state health model to predict bearing failures before they occur. The model employs a regression-based method to detect health state transition points and applies an exponential random coefficient model with a Bayesian updating process to estimate time-to-failure distributions. A model training framework is also introduced to make our proposed model applicable to more bearing instances in the same system setting. The proposed method has been tested on a publicly available bearing prognostics dataset. Case study results show that the proposed method provides accurate failure predictions across several system failures, and that the training approach can significantly reduce the time necessary to generate an effective, generalized model.

Non-Hermiticity-induced reentrant localization in a quasiperiodic lattice

In this paper, we demonstrate that the non-Hermiticity can induce reentrant localization in a generalized quasiperiodic lattice. Specifically, by considering a nonreciprocal dimerized lattice with staggered quasiperiodic disorder, we find that the localization transition can appear twice by increasing the disorder strength. We also unravel a multi-complex-real eigenenergy transition, whose transition points coincide with those in the localization phase transitions. Moreover, the impacts of boundary conditions on the localization properties have been clarified. Finally, we study the wavepacket dynamics in different parameter regimes, which offers an experimentally feasible route to detect the reentrant localization.

Critical points of the random cluster model with Newman-Ziff sampling

We present a method for computing transition points of the random cluster model using a generalization of the Newman-Ziff algorithm, a celebrated technique in numerical percolation, to the random cluster model. The new method is straightforward to implement and works for real cluster weight $q>0$. Furthermore, results for an arbitrary number of values of $q$ can be found at once within a single simulation. Because the algorithm used to sweep through bond configurations is identical to that of Newman and Ziff, which was conceived for percolation, the method loses accuracy for large lattices when $q>1$. However, by sampling the critical polynomial, accurate estimates of critical points in two dimensions can be found using relatively small lattice sizes, which we demonstrate here by computing critical points for non-integer values of $q$ on the square lattice, to compare with the exact solution, and on the unsolved non-planar square matching lattice. The latter results would be much more difficult to obtain using other techniques.

Learning Humanities and Ethics of Aging Through the Lens of an Avatar Creation

The main goal of teaching the humanities and ethics of aging is to understand the perspectives of older individuals as they address the challenges and opportunities presented across the aging spectrum. To encourage understanding of this humanistic and ethical process, students were given an assignment to select a profile of an older person with pre-selected characteristics that they then develop into their avatar, a virtual companion, to accompany them through the course. This assignment included three iterations of the avatar narrative related to what is studied in class around major life transition points related to work, housing, and end of life. These assignments included the creation of Mind Maps which illustrate their avatar’s ongoing concerns related to their environment including their social determinants of health. The avatar’s formative development throughout the course brought forward discussions around identity, safety, autonomy, and person-centeredness in terms of gerontological practice and policy.

Elimination of Interionic Hydrogen Bonding in The Imidazolium-Based Ionic Liquids

Hydrogen bonding is a phenomenon of paramount importance in room-temperature ionic liquids. The presence or absence of the hydrogen bond drastically alternates self-diffusion, shear viscosity, phase transition points, and other key properties of a pure substance. For certain applications, the presence of cation-anion hydrogen bonding is undesirable. In the present paper, we investigate perspectives of removing the hydrogen...fluorine interionic attraction in the imidazolium borates, the strongest non-covalent interaction in this type of system. Chemical modification of the tetrafluoroborate anion not only eliminates hydrogen bonding but also changes the most thermodynamically preferable orientation of the cation in the vicinity of the anion. Although the most acidic hydrogen atom of the imidazole ring remains the paramount electrophilic center of the cation, it does not engender a strong electrostatically driven coordination pattern with the properly modified anions. The reported new physical insights help compose more robust ionic liquids and tune solvation properties of the imidazolium-based RTILs.

Technology for Conversion of Computer Tomography Results into Three-Dimensional Models

The development relates to information technology and can be used to process medical images. This task is achieved by the fact that DICOM files containing the results of computed tomography of the human head are subject to correction. They change the color of the pixels at the transition points from black to gray or vice versa, and also replace the black pixel with white. As a result, the percentage of loss of information about small bones is reduced from 22-31 % to 3-5 %, and, therefore, the accuracy of the three-dimensional model of the facial skull of the human head is increased. All this contributes to a significant improvement in the quality of facial surgery.

Using social domain theory to seek critical consciousness with young children

The question of ‘developmental appropriateness’ in education can be both empowering and inhibiting. When are students ‘ready’ to talk about social injustices and systemic inequalities? How might educators introduce social inequities using developmental findings about reasoning? This article presents social domain theory as a lens through which educators can approach critical consciousness education with young children. An overview of Freire’s critical consciousness construct is presented, including educational interventions, methods, and approaches that support critical consciousness. An overview of social domain theory is also presented. Social domain theory is a developmental theory of sociomoral reasoning that describes three domains of social knowledge that develop independently, and get applied/coordinated/prioritized differently in context by individuals. This theory, and the research stemming from it, has shown that there are developmental transition points during which children come to view their previous logic as inadequate, and are likely to shift their understandings of moral, conventional, and personal issues. A parallel is drawn between these transition points and the process of wrestling with and overturning ‘contradictions’ in critical consciousness education. Contradictions are theorized as dehumanizing power dynamics that show up in students’ everyday circumstances. This article provides tables outlining example contradictions for young children, key domain–related reasoning shifts for young children, and examples for how to create lesson plans that take these two factors into account. Finally, we propose a method of facilitating self-assessment of critical consciousness with young children. Self-reflection questions are provided for teachers and students.

Electrodynamics of Topologically Ordered Quantum Phases in Dirac Materials

First-principles calculations of the electronic ground state in tantalum arsenide are combined with tight-binding calculations of the field dependence of its transport model equivalent on the graphene monolayer to study the emergence of topologically ordered quantum states, and to obtain topological phase diagrams. Our calculations include the degrees of freedom for nuclear, electronic, and photonic interactions explicitly within the quasistatic approximation to the time-propagation-dependent density functional theory. This field-theoretic approach allows us to determine the non-linear response of the ground state density matrix to the applied electromagnetic field at distinct quantum phase transition points. Our results suggest the existence of a facile electronic switch between trivial and topologically ordered quantum states that may be realizable through the application of a perpendicular electric or magnetic field alongside a staggered-sublattice potential in the underlying lattice. Signatures of the near field electrodynamics in nanoclusters show the formation of a quantum fluid phase at the topological quantum phase transition points. The emergent carrier density wave transport phase is discussed to show that transmission through the collective excitation mode in multilayer heterostructures is a unique possibility in plasmonic, optoelectronic, and photonic applications when atomic clusters of Dirac materials are integrated within nanostructures, as patterned or continuous surfaces.

Multiple magnetic phase transitions with different universality classes in bilayer La$$_{1.4}$$Sr$$_{1.6}$$Mn$$_{2}$$O$$_7$$ manganite

Here, we report three magnetic transitions at 101 K (T$$_{C1}$$ C 1 ), 246 K (T$$_{C2}$$ C 2 ) and 295 K (T$$_{C3}$$ C 3 ) in bilayer La$$_{1.4}$$ 1.4 Sr$$_{1.6}$$ 1.6 Mn$$_{2}$$ 2 O$$_7$$ 7 . The second order phase transitions have been identified at these transition points with the help of change in entropy analysis and modified Arrott plots (MAPs). The critical behavior around T$$_{C1}$$ C 1 , T$$_{C2}$$ C 2 and T$$_{C3}$$ C 3 have been studied by MAPs and Kouvel–Fisher method. Based on these analyses four magnetic phases are: (1) 2D Ising ferromagnetic (FM) below T$$_{C1}$$ C 1 ,(2) 2D Heisenberg canted antiferromagnetic (CAFM-I) and FM clusters in temperature range T$$_{C1}$$ C 1 < T < T$$_{C2}$$ C 2 , (3) 2D Heisenberg CAFM-II and FM clusters with non magnetically interacting planes in temperature range T$$_{C2}$$ C 2 < T < T$$_{C3}$$ C 3 and (4) paramagnetic for T > T$$_{C3}$$ C 3 .