Forced Transition Research Articles

Using a Piecewise Linear Spring to Approximate an Essentially Nonlinear Spring: Design and Validation

This study develops a procedure for designing a piecewise linear spring (PLS) to approximate an essentially nonlinear spring (ENS). The PLS is constructed with a cantilever beam constrained by a pair of single- or double-stop blocks. The design begins by determining the restoring force of the desired ENS using the equivalent stiffness which quantifies the characteristics of a cubic polynomial. Then, based on the force-deflection model of a cantilever beam with an overhang, the configuration parameters for single- and double-stop blocks are determined through a least squares optimization. The numerical simulation demonstrates that the PLS with double-stop blocks approximates the desired ENS behaviors better in terms of the restoring force, potential energy, and instantaneous frequency transition. An experiment apparatus with four tunable stop blocks is developed to validate the numerical simulation results. The static experimental tests verify the accuracy of the analytical model. The dynamic experimental tests show that within the achievable range of displacement, the PLSs behave similarly to the ENS. However, the maximum displacement is smaller than the designed one due to an insufficient exciting force. To address this issue, the desired displacement range is reduced by half. With the redesigned PLSs, the improved experimental results are obtained.

The Emotional Implications of a Hypertrophic Cardiomyopathy Diagnosis in a Retired Athlete: An Autoethnographic Approach

The purpose of this study was to advance knowledge and understanding of the emotional implications retired athletes experience when diagnosed with hypertrophic cardiomyopathy. This study employed an autoethnographic method to explore the consequences of living with this potentially life-threatening heart condition from a first-person narrative, using the account-making model of coping and loss as framework. The results illuminate the lived experience of someone diagnosed with hypertrophic cardiomyopathy and subsequent forced transition out of high-performance sport. This study provides practitioners with insights into this topic so that relevant and tailored interventions can be implemented to help retiring athletes who are diagnosed with hypertrophic cardiomyopathy cope with the career transition process. Notably, this paper also offers a full, complete autoethnography rather than extracts of autoethnographic writing typically provided in journal articles due to formatting restrictions. Thus, we showcase the valuable contribution this methodology has to offer scholars and practitioners.

National Movement Formation in the BSSR and Its Position on the Union State Preservation in 1988–1989

The article explores the history of the emergence and development of the Belarusian opposition organization Belarusian Popular Front (BPF) and examines the history of Belarusian opposition organizations origin, the reasons for their appearance since the 1970s. Special attention is paid to the historical context, the all–Union processes of the specified period, in particular Perestroika, the policy of glasnost and the key event that influenced the formation of the Belarusian opposition — the XIX party conference in 1988. The article describes in detail the process and reasons for the transition of opposition political forces in the BSSR to a single national movement, as well as the emergence of the organization preceding the BPF — the Martyrology of Belarus. Special attention is paid to the personalities who stood at the origins of the BPF — Z. Pazniak, V. Bykov and others. A separate analysis is devoted to the development of the movement in the run-up to the 1989 elections and the electoral struggle. This stage is divided into two parts — the second half of 1988 and the first half of 1989. The political actions of the BPF, such as the rally on the Dzyady holiday and the rally at the Dynamo stadium, are analyzed in detail. The election program of the Belarusian Popular Front “Fifteen points” concerning both the Belarusian SSR and the Soviet state is analyzed in detail. It is argued that the period of political struggle of 1988–1989 was only the start. It will be followed by a new round of struggle in 1990. As a result of the research, it can be concluded that the Belarusian Popular Front managed to get deputies to the First Congress of People’s Deputies thanks both to the organization representatives activities and to the policy of Mikhail Gorbachev.

Адвокатуючи диявола, або позитивні соціальні ефекти вимушеного переходу до дистанційного формату навчання в українській вищій школі

This article explores the potential and actual positive social effects of the forced transition to distance learning in Ukrainian higher education institutions, particularly those in frontline regions during 2022–2024. While the transition is often viewed negatively, this study aims to present the other side, focusing on the benefits at three levels: everyday life of participants, institutional, and societal. This study is part of the project “Social Effects and Challenges of Distance Learning in the Higher Education of Ukraine: from COVID-19 to the War”, which is implemented by the one of the authors within the framework of “Cambridge – NRFU 2022. Individual research (developments) grants for researchers in Ukraine (supported by the University of Cambridge, UK)”. Using data from comprehensive research, including desk research, expert interviews, focus groups with students and graduates, and a quantitative online survey of students, the article reveals both short-term and long-term benefits of transition to distance format of education. At the individual level, distance learning saves time, enhances flexibility for combining study and work, and fosters self-discipline. At the institutional level, it promotes the development of digital skills, inclusivity, and international collaboration, etc. At the societal level, it promotes decentralization, equal access to education, and the transformation of labor markets. Although limitations such as technical issues and potential biases are acknowledged, the study argues that distance education provides some opportunities for progressive change in Ukrainian higher education. However, even after a detailed analysis of the positive effects, the authors of the article remain skeptical about the distance format of higher education.

Theoretical Thinking on the Development of New Quality Productive Forces According to Local Conditions in Heilongjiang Province

The new quality productive forces reflects the systematic remodeling and revolutionary transition of the old productive forces, which is the quality of productivity in line with the requirements of high-quality development. The formation of new quality productive forces can effectively energize the revitalization and development of Heilongjiang Province. From the perspective of the revitalization of the old industrial base in Northeast China, opportunities, advantages and challenges coexist in the development of new quality productive forces in Heilongjiang Province. Based on the current situation, the practical path for the development of new quality productive forces according to local conditions in Heilongjiang Province is proposed: Cultivate innovative thinking leading the development of new quality productivity, form the industrial base for the development and growth of new quality productivity, shape the innovation economic system for the development of new quality productivity, and build innovation clusters of new quality productivity.

An innovative strategy for improving ductility of seawater sea-sand engineered cementitious composites beam reinforced with GFRP bar

Seawater sea-sand engineered cementitious composites (SS-ECC) members with glass fiber reinforced polymer (GFRP) bars have inferior ductility due to the brittle nature of GFRP bars. In the current research, an enlarged head anchorage system (EHAS) was recommended to improve the ductility of GFRP bars reinforced SS-ECC beams. To explore the bond characteristics between SS-ECC and GFRP bars with EHAS, a total of 39 specimens were tested by pull-out loading. The influences of enlarged head shape, stirrup spacing and SS-ECC's strength grade on the bond characteristics were experimentally investigated. GFRP longitudinal bars in specimens with EHAS presented rupture failure rather than anchorage failure. EHAS could effectively realize the slip hardening of GFRP bars in low strength SS-ECC, and ensure the reliable bond of GFRP bars in high strength SS-ECC. Additionally, the failure mechanism of specimens under pull-out loading was explored by finite element analysis (FEA). The pull-out resistance was mainly provided by EHAS in force transition stage and slip hardening stage. The influences of fiber reinforced polymer (FRP) bar type on the bond performance were investigated by FEA. EHAS could realize the slip-hardening behaviors of aramid, basalt and carbon FRP bars in normal strength SS-ECC. More importantly, to verify the effectiveness of the proposed ductility enhancement strategy, SS-ECC beams reinforced with GFRP bars were tested by four-point bending. These beams with different enlarged head shapes possessed excellent ductility and strong ultimate deformation capacity. It was recommended that low strength SS-ECC and GFRP bars with EHAS were jointly utilized to enhance the ductile performance of the beams.

Development of the BOLT-2 Roughness Experiment for Flight

A sounding rocket research flight called BOLT-2, which stands for Boundary Layer Turbulence 2, was initiated with the goal of studying hypersonic boundary-layer transition and turbulence. The BOLT-2 research vehicle is based on a three-dimensional geometry with concave surfaces and swept leading edges that provides two separate and distinct, also redundant, flowpaths for conducting measurements. One side of BOLT-2 is dedicated to smooth surface transition and turbulence, to better study the natural instability processes, whereas the other has been assigned to study forced transition and turbulence using discrete roughness trips. The present paper is intended to document the primary drivers and decisions made that lead up to finalizing the roughness-side experiment for the BOLT-2 flight.

Challenges and opportunities of digital transformation in Ukrainian education

An important and necessary trend in the modern Ukrainian education system is the digitalisation of the educational process due to the forced transition of many educational institutions to distance learning due to the coronavirus pandemic and the Russian-Ukrainian war. The purpose of the article is to theoretically substantiate the challenges and opportunities for the introduction of digital learning technologies in Ukrainian educational institutions. The following methods were used to write the article and to reveal its purpose: conceptual and terminological analysis, comparative and contrastive analysis, analysis, synthesis, comparison, classification, systematisation and generalisation. The study found that, despite the many opportunities provided by the digital learning environment, including the development of software applications for the development of students' practical experience and access to high-quality and diverse sources of information, the education system in Ukraine needs to rethink the content, determine models of digitalisation of educational institutions, master the digital competencies of all participants in the educational process, and actively use the tools of Google Meet, Zoom, Microsoft Teams, and Cisco Webex, It is determined that the services are not without drawbacks in use, but their effective use contributes to digitalisation. The scientific novelty of the obtained results lies in the interpretation of the concept of “challenges of introducing digital technologies in education” and the identification of the main obstacles and ways to ensure the process of digitalisation of education. The conclusions recommend ways to overcome the difficulties of digitalisation of education, in particular, the need to create a model of digital transformation of an educational institution based on three models: a functionally independent model of information management; a concentric model of information technology for digital transformation of an educational institution; and a model of interlayer information interaction. Prospect for further research is to study the mechanisms for adapting teacher training systems to the use of digital technologies in the classroom.

Psychosocial factors of first year students’ adaptability in the higher educational establishment in the situation of the forced transition to online learning

Alongside the usual difficulties first-year students face in adapting to university, in the situation of the forced transition to remote or online learning, they have to cope with additional challenges. The psychosocial factors (family status, current conflicts, emotional support, computer skills, subjective assessment of health and satisfaction with learning, etc.) facilitating or hindering their adaptation to this situation are therefore of particular interest. The purpose of the study was to reveal such factors among medical (N = 93) and economics (N = 111) students with different levels of adaptability in the higher educational establishment (using the 2019 coronavirus pandemic as an example). The results showed that successfully adapted students of both majors, in contrast to students with low levels of adaptability, noted the presence of emotional support and minor conflicts (or lack of them). In addition, highly adapted economics students indicated professional computer skills; medical students indicated good technical equipment for mastering the curriculum, greater satisfaction with learning, and agreed that their field of study permits partial online learning. Both universal psychosocial factors of adaptation of students in higher education, i.e. those noted by previous researchers as necessary conditions for successful adaptation of first-year students, and, in our opinion, specific ones, which are conditioned by the forced transition to online learning, were identified. The results may be useful for educational psychologists when working with poorly adapted students in the situation of the forced transition to online learning.

Investigation into the Hot-Forming Limit for 22MnB5 Hot-Forming Steel under a Stamping Process

Hot-forming technology for 22MnB5 hot-forming steel (22MnB5 HF steel) plates has been widely used in the automobile manufacturing industry in recent years. Physical simulation and numerical modeling were carried out in order to determine the forming limit of a 22MnB5 steel plate for the stamping process. The deformation experiments were performed in a temperature range of 600~900 °C and a strain rate range of 0.1~10 s−1. In the uniaxial tensile tests, it was found that at the forming temperature of 600 °C, the condition of dynamic recrystallization was not fully reached, and thus the corresponding tensile strength was much larger than that at other deformation temperatures. In the numerical simulation of bulging experiments, it was found that 22MnB5 steel had good formability when the initial deformation temperature was high and the forming speed was low by using the instability criterion, combining the maximum punch force and strain path transition. The forming limit diagram of 22MnB5 steel at a temperature of 700 °C and tool speed of 25 mm/s was obtained by means of simulation and a hot stamping experiment. The establishment of the forming limit of the 22MnB5 steel plate can provide theoretical and technical guidance for the hot-forming process.

Bistable Aerial Transformer: A Quadrotor Fixed-Wing Hybrid That Morphs Dynamically Via Passive Soft Mechanism

Abstract Aerial vehicle missions require navigating trade-offs during design, such as the range, speed, maneuverability, and size. Multi-modal aerial vehicles enable this trade-off to be negotiated during flight. This paper presents a Bistable Aerial Transformer (BAT) robot, a novel morphing hybrid aerial vehicle that switches between quadrotor and fixed-wing modes via rapid acceleration and without any additional actuation beyond those required for normal flight. The design features a compliant bistable mechanism made of thermoplastic polyurethane (TPU) that bears a large mass at the center of the robot’s body. When accelerating, inertial forces transition the vehicle between its stable modes, and a four-bar linkage connected to the bistable mechanism folds the vehicle’s wings in and out. The paper includes the full robot design and a comparison of the fabricated system to the elastodynamic simulation. Successful transitions between the two modes in mid-flight, as well as sustained flight in each mode indicate that the vehicle experiences higher agility in the quadrotor mode and higher flight efficiency in the fixed-wing mode, at an energy equivalent cost of only 2 s of flight time per pair of transitions. The vehicle demonstrates how compliant and bistable mechanisms can be integrated into future aerial vehicles for controllable self-reconfiguration for tasks such as surveillance and sampling that require a combination of maneuverability and long-distance flight.

Surgical technique: proximal extension of instrumentation using sublaminar bands for salvage of postoperative proximal junctional failure in pediatric patients.

Proximal junctional failure is a complication that can occur following posterior spine surgery with instrumentation. The ability to surgically revise this complication is important for the spine surgeon, yet there is little literature on the topic, especially for pediatric patients. The technique we describe involves proximal extension of the existing instrumentation using paired levels of sublaminar bands that allows for a smooth transition of forces at the junction of instrumented and non-instrumented regions of the spine. The results of this technique have been promising with a case series demonstrating improved radiographic and clinical outcomes for eight children at a minimum of 1year follow-up. This a reliable, effective, and safe technique for salvage of PJF in children that uses posterior osteotomies and proximal extension of the instrumentation using sublaminar bands, resulting in gradual load sharing correction to restore sagittal balance.

High Dynamic Range Probing of Single-Molecule Mechanical Force Transitions at Cell-Matrix Adhesion Bonds by a Plasmonic Tension Nanosensor.

Mechanical signals in animal tissues are complex and rapidly changed, and how the force transduction emerges from the single-cell adhesion bonds remains unclear. DNA-based molecular tension sensors (MTS), albeit successful in cellular force probing, were restricted by their detection range and temporal resolution. Here, we introduced a plasmonic tension nanosensor (PTNS) to make straight progress toward these shortcomings. Contrary to the fluorescence-based MTS that only has specific force response thresholds, PTNS enabled the continuous and reversible force measurement from 1.1 to 48 pN with millisecond temporal resolution. We used the PTNS to visualize the high dynamic range single-molecule force transitions at cell-matrix adhesions during adhesion formation and migration. Time-resolved force traces revealed that the lifetime and duration of stepwise force transitions of molecular clutches are strongly modulated by the traction force through filamentous actin. The force probing technique is sensitive, fast, and robust and constitutes a potential tool for single-molecule and single-cell biophysics.

The potential of proximal junctional kyphosis prevention using a novel tether pedicle screw construct: an in silico study comparing the influence of standard and dynamic techniques on adjacent-level range of motion and load pattern.

A tether pedicle screw (TPS) enables individual stepless pretensioning and is placed at one or two levels above the upper instrumented vertebra (UIV+1 and UIV+2, respectively). This study aimed to evaluate a novel customized TPS for the prevention of proximal junctional kyphosis (PJK) and to investigate the potential to generate a smoother force transition from cranial to long fusion during trunk flexion, instead of an abrupt change at the UIV, following adult spinal deformity surgery. A finite element model was designed based on an adult patient with spinal deformity instrumented from T10 to S1. Five different sagittal balance types and implant configurations were tested. The proximal range of motion (ROM) and intervertebral stress were examined, with a special focus on their respective discontinuities. Tension shielding at UIV/UIV+1 by the TPS was consistent irrespective of sagittal profiles. The use of TPSs at UIV+1 and UIV+2 increased the efficacy in reducing spinal ROM discontinuity at UIV/UIV+1, as compared with the use of TPSs at UIV+1 only. Through the use of two pairs of TPSs cranial to the UIV, the optimal tension configuration could be defined to avoid a reduction effect at UIV+1. Neither the addition of transition rods to the TPSs nor the use of transition rods in combination with standard pedicle screws improved the junctional mechanics when compared with TPSs at UIV+1/UIV+2. A smoother motion discontinuity at the UIV can be achieved via implementation of a TPS strategy. This new technology shows favorable in silico mechanics for reducing the risk of PJK.

The interplay of the innovation cycle, build time, lifetime, and deployment rate of new energy technologies: a case study of nuclear fusion energy

Abstract This article analyses how a forced transition to low-carbon energy impacts the innovation of new energy technologies. We apply the insights to nuclear fusion, potentially a large provider of carbon-free energy currently attracting billions in private investments. We discuss the ‘fastest-feasible-growth (FFG)’ curve for transitions: exponential growth followed by linear growth, where the rate of latter is limited by the inverse lifetime of the installation. We analyse how innovation is affected if, during rapid deployment, a technology progresses through several generations. We identify key timescales: the learning time, the generation time, the build time, and the exponential growth time of the early deployment phase and compare these for different energy technologies. We distinguish learning rate-limited and generation-time-limited innovation. Applying these findings to fusion energy, we find that a long build time may slow deployment, slow learning, and promote early technology lock-in. Slow learning can be remedied by developing multiple concepts in parallel. Probabilistic analysis of value implies that the optimal strategy is to parallelize the development of many concepts. This concurs with the present surge in private investment in multiple concepts. For this strategy to be successful, the build time of the power plant must be minimized. This requirement favours concepts that lend themselves to modularization and parallelization of production and assembly.

Waiting Nets: State Classes and Taxonomy

In time Petri nets (TPNs), time and control are tightly connected: time measurement for a transition starts only when all resources needed to fire it are available. Further, upper bounds on duration of enabledness can force transitions to fire (this is called urgency). For many systems, one wants to decouple control and time, i.e. start measuring time as soon as a part of the preset of a transition is filled, and fire it after some delay and when all needed resources are available. This paper considers an extension of TPN called waiting nets that dissociates time measurement and control. Their semantics allows time measurement to start with incomplete presets, and can ignore urgency when upper bounds of intervals are reached but all resources needed to fire are not yet available. Firing of a transition is then allowed as soon as missing resources are available. It is known that extending bounded TPNs with stopwatches leads to undecidability. Our extension is weaker, and we show how to compute a finite state class graph for bounded waiting nets, yielding decidability of reachability and coverability. We then compare expressiveness of waiting nets with that of other models w.r.t. timed language equivalence, and show that they are strictly more expressive than TPNs.

Static and dynamic plantar foot shape following long-term use of military boots

Foot structure can be influenced by various factors, such as footwear, body weight and physical activity. A change in foot structure can alter shock absorption and force transition. The main objective of this study is to investigate the effect of the long-term use of military boots on foot shape parameters. Thirty military and thirty non-military subjects participated in this case-control study. All participants had been regularly wearing military boots for the past 12 years. After introducing the experiment, static and dynamic footprints were recorded via paper and ink while standing and walking. The footprints were analysed using ImageJ software to extract foot width indices, area indices, truncated arch index, footprint index and arch angle index. The findings indicated no significant difference in comparison static and dynamic variables in the military and non-military groups (p ≥ 0.05). However, there was a significant difference between the two groups in both static (midfoot area, arch index (AI), truncated arch index, footprint index and arch angle index) and dynamic (midfoot width, Staheli Index (SAI), truncated arch index and arch angle index) conditions, when static and dynamic variable were compared (p < 0.05). Findings revealed the military personnel have low arch, making them susceptible to musculoskeletal disorders. To mitigate this risk, it is recommended that military boots be reassessed or that insoles be used. Furthermore, it is suggested that military boots be limited to specific activities and fewer hours of usage to avoid potential health issues.

Modeling dynamic stall of an airfoil with vortex generators using a double‐wake panel model with viscous–inviscid interaction

AbstractVortex generators (VGs) have been widely applied to wind turbines thanks to their potential to increase aerodynamic performance. Due to the complex inflow perceived by a rotor and the proneness to flow separation, VGs on wind turbines usually experience highly unsteady flow. While there are models that exist to simulate the steady effects of VGs, we lack a fast and efficient tool to model the unsteady performance of airfoils equipped with VGs. This paper adopts an unsteady double‐wake panel model with viscous–inviscid interaction developed to simulate a vertical axis turbine in dynamic stall, adding the capability of predicting the dynamic aerodynamic performance of VG‐equipped airfoils. The results of a series of steady and unsteady cases of an airfoil with different VG configurations in various pitch motions in free and forced transition are verified against experimental data. Results show that the double wake model offers results with sufficient accuracy compared with experimental data to claim the model's validity in a preliminary evaluation of an airfoil's capability to prevent stall with VGs. A few limitations, including the accuracy in prediction the transition location, separation, and reattachment, have been identified for future development.

Inclusive Technology-mediated School-family Communication in Contexts of Social Violence: A Proposal for Guidelines for Schools and Families in Gaza

I-CAN: Independence, Capability, Autonomy, iNclusion was an international cooperation project run in 2018-2021, which involved 15 selected Gaza Strip’s schools, whose objective was to promote the full inclusion of people with disabilities. The project was articulated in two main actions: the first was the establishment of an “Holistic and Innovative Centre”, created to support educators and families in the promotion of initiatives directed at building inclusive communities; the second was a qualitative research, which explored the implications that the lockdown and the forced transition towards technology-mediated communication had on school-family relationship.

Group Belonging and Social Identities in the Transition of Asylum-Seekers in Greece: Longitudinal Pathways to Adjustment.

Millions of forced migrants settling in host countries often struggle to adjust to their new life. As their inclusion and adjustment within receiving societies has become a global social challenge, studying the factors that support their successful transition is an important topic of research inquiry. The present three-wave longitudinal study examined the role of group belonging and social identification in facilitating the transition of 60 sub-Saharan African asylum-seekers to Greece. Drawing upon the Social Identity Model of Identity Change (SIMIC), we investigated how multiple group memberships before migration, social identity continuity, and social identity gain related to their adjustment over 8 months. On the between-person level, multiple group belonging before migration indirectly contributed to better person-average levels of sociocultural adjustment, physical health functioning and satisfaction, psychological distress, and life satisfaction, by way of higher person-average levels of social identity continuity and/or social identity gain. However, multiple groups before migration also had a direct negative effect on the overall levels of psychological distress. On the within-person level, positive changes in social identity continuity and gain were related to positive changes in different adjustment-related outcomes over time. Our findings are consistent with SIMIC and highlight the importance of group belonging and associated social identities in forced migrants' transition, in ways that may pave the way for the development of social identity interventions to promote their health, well-being, and successful integration. Future longitudinal and experimental evidence with larger and more diverse samples of forced migrants is needed to establish the generalizability and causality of the observed associations.