Cyclic Motion Research Articles

The mean reversion/persistence of financial cycles: Empirical evidence for 24 countries worldwide

Research background: The globalization trend has inevitably enhanced the connectivity of global financial markets, making the cyclicality of financial activities and the spread of market imbalances have received widespread attention, especially after the global financial crisis. Purpose of the article: To reduce the negative effects of the contagiousness of the financial cycles, it is necessary to study the persistence of financial cycles and carve out the total connectedness, spillover paths, and sources of risks on a global scale. In addition, understanding the relationship between the financial cycle and economic development is an important way to prevent financial crises. Methods: This paper adopts the nonlinear smoothing transition autoregressive (STAR) model to extract cyclical and phase characteristics of financial cycles based on 24 countries during 1971Q1?2015Q4, covering developed and developing countries, the Americas, Europe, and Asia regions. In addition, the frequency connectedness approach is used to measure the connectedness of financial cycles and the relationship between the global financial cycle and the global economy. Findings & value added: The analysis reveals that aggregate financial cycles persist for 13.3 years for smoothed and 8.7 years for unsmoothed on average. The national financial cycles are asynchronous and exhibit more prolonged expansions and faster contractions. The connectedness of financial cycles is highly correlated with systemic crises and contributes to the persistence and harmfulness of shocks. It is mainly driven by short-term components and exhibits more pronounced interconnectedness within regions than across regions. During the financial crisis, the global financial cycle movements precede and are longer than the business fluctuations. Based on the study, some policy implications are presented. This paper emphasizes the impact of systemic crises on the persistence of financial cycles and their connectedness, which contributes to refining research related to the coping mechanisms of financial crises.

ICEP: An Instrumented Cycling Ergometer Platform for the Assessment of Advanced FES Strategies.

Functional electrical stimulation (FES) cycling has seen an upsurge in interest over the last decade. The present study describes the novel instrumented cycling ergometer platform designed to assess the efficiency of electrical stimulation strategies. The capabilities of the platform are showcased in an example determining the adequate stimulation patterns for reproducing a cycling movement of the paralyzed legs of a spinal cord injury (SCI) subject. Two procedures have been followed to determine the stimulation patterns: (1) using the EMG recordings of the able-bodied subject; (2) using the recordings of the forces produced by the SCI subject's stimulated muscles. the stimulation pattern derived from the SCI subject's force output was found to produce 14% more power than the EMG-derived stimulation pattern. the cycling platform proved useful for determining and assessing stimulation patterns, and it can be used to further investigate advanced stimulation strategies.

Three-dimensional trenches induced by lateral riser-soil interaction and their influence on the behavior of SCR

Although the lateral oscillation of steel catenary risers (SCRs) contributes to trench production, traditional riser-seabed models cannot simulate the process. This study proposes a modified lateral riser-seabed interaction model and integrates it into the SCR model based on the vector form intrinsic finite element (VFIFE) method to simulate the trench formation process. The effects of the loading history, extra soil berm resistance, and cyclic vertical riser-soil interactions were included in the soil model. A 3D trench could be developed under the cyclic out-of-plane movement of the SCR. The trench formation process, seabed resistance distribution, axial tension, bending moment, and stress range distribution of the SCR were discussed in detail to illustrate the effects of the soil model. Different loading amplitudes and nonlinear soil parameters were chosen to determine their influence on the trench shape and distribution of the horizontal seabed resistance. The developed trenches were then inserted into the fresh SCR model before executing the dynamic analysis, in which only the cyclic heave motion was applied to the hang-off point. The simulation results showed that the trenches produced by cyclic sway motions beneficially influenced the fatigue life of the SCR. However, the effect would differ with the profiles.

Effects of Geogrid Reinforcement on the Backfill of Integral Bridge Abutments

The construction of integral bridges is one of the most effective methods to reduce bridges’ construction and in-service costs. However, there are associated geotechnical problems with their abutments backfill due to the integrated abutments. The main goal of this study is to evaluate and quantify the benefits of geogrid reinforcement for reducing the backfill’s geotechnical problems. For this purpose, using small-scale physical modeling, the benefits of geogrid reinforcing of the backfill of an integral abutment bridge subjected to cyclic movements are evaluated. The results are then compared with a previous study performed on unreinforced backfill and two types of geocells. In this study, 120 loading cycles are applied to geogrid-reinforced soil to simulate the cyclic loadings on integral abutment backfill due to seasonal abutment displacement. The horizontal reaction load at the top of the wall, changes in pressure behind the wall, and deformation in backfill soil are measured during the test. Then the results are discussed in terms of equivalent peak lateral soil coefficient (Kpeak), lateral earth pressure coefficient (K*), and normalized settlement behind the wall (Sg/H). The derived lateral soil coefficients and settlement behind the abutment show that geogrid substantially reduces pressure and settlements after 120 cyclic loads. Based on the results, Kpeak and K* of the geogrid-reinforced backfill decrease by up to 36%, and Sg/H behind the wall decreases by 62%. In addition, the comparison of the results for geogrid with two geocell types shows that geogrid is more efficient in terms of lateral soil coefficients.

An optical method to monitor transparent contact interfaces during high frequency shear vibration cycles

Contacting interfaces provide frictional damping in jointed structures subjected to high dynamic loads. Predicting this frictional damping during vibration cycles is highly important since it strongly affects the dynamic response of the assembly and hence the lifetime of parts. Since frictional damping is heavily influenced by the contact condition at the interface, the most direct and insightful approach is thereby to actively monitor the contact interface. Although several methods have already been proposed to monitor the contact interfaces quasi-statically or in pre-sliding, such as digital image correlation, X-Ray and ultrasound, only limited data is available of the frictional interface behaviour during high frequency vibration.To provide a better insight into the contact interface behaviour during high frequency cyclic motion, an optical method is here developed based on transparent friction specimens and total internal reflection, and applied to an existing friction test rig. The resulting measurements across the whole interface show a large variation in the real area of contact during each vibration cycle, which could be linked to the kinematics of the contact interface. This large variation is observed for the first time in high frequency oscillating contacts and is attributed to ageing effect and fracture of asperities. These two effects dominate the contact mechanism at different sliding velocities and induce variations in the real area of contact during each vibration cycle. These results suggest that the mechanisms behind high frequency contact behaviour are more complex than what commonly assumed in dynamics simulations.

Wearable and Stretchable SEBS/CB Polymer Conductive Strand as a Piezoresistive Strain Sensor

A wearable and stretchable strain sensor with a gauge factor above 23 was prepared using a simple and effective technique. Conducting nanocomposite strands were prepared from styrene-b-(ethylene-co-butylene)-b-styrene triblock copolymer (SEBS) and carbon black (CB) through a solvent-processing method that uses a syringe pump. This novel nanocomposite preparation technique is a straightforward and cost-effective process and is reported in the literature for the first time. The work included two stages: the flexible nanocomposite preparation stage and the piezoresistive sensor stage. Depending on its molecular structure, the thermoelastic polymer SEBS is highly resilient to stress and strain. The main aim of this work is to fabricate a highly flexible and piezoresistive nanocomposite fibre/strand. Among the prepared composites, a composite corresponding to a composition just above the percolation threshold was selected to prepare the strain sensor, which exhibited good flexibility and conductivity and a large piezoresistive effect that was linearly dependent on the applied strain. The prepared nanocomposite sensor was stitched onto a sports T-shirt. Commercially available knee and elbow sleeves were also purchased, and the nanocomposite SEBS/CB strands were sewn separately on the two sleeves. The results showed a high sensitivity of the sensing element in the case of breathing activity (normal breathing, a 35% change, and deep breathing at 135%, respectively). In the case of knee and elbow movements, simultaneous measurements were performed and found that the sensor was able to detect movement cycles during walking.

Design and implementation of spanwise lift and gust control via arrays of bio-inspired individually actuated pneumatic flaplets

PurposeCovert feathers on avian wings can show dynamic pop-up behaviour in rapid succession as a reaction to turbulent gusts. The purpose of this paper is to understand the possible flow control mechanism induced during such dynamic motion cycles. A model aerofoil is designed with suction side spanwise control of rows of bio-inspired flaplets.Design/methodology/approachA NACA 0012 aerofoil is equipped with a spanwise row of eight flaplets at 80% chord, connected to pneumatic actuators and can be deployed to max 15° in a prescribed open–hold–close manner. The model is placed in a water tunnel and flow measurements are done in the wake of the flaps during a cycle using particle image velocimetry.FindingsDuring opening, boundary layer flow is sucked into the void space between the wing surface and the flaplet, which induces backflow underneath the flaplet and traps the fluid inside. This fluid is expelled downstream during closure, which generates a forward directed jet as seen by the formation of a vortex-ring like structure with higher axial momentum. The entrainment of the jet leads to the re-energising of the boundary layer flow further upstream.Originality/valueThis paper presents a furtherment of understanding of the action of pop-up feathers for separation control. The actuation of the bio-inspired flaplets shows a flow vectorising effect which can be used for active separation and gust control. In the case of incipient separation, flaplet action can act to re-attach the flow because of the jet entrainment effect.

More Predictable and Less Automatized Movements during Walking -not during Repetitive Punching- in Knee Osteoarthritis

Using the non-affected leg as stable frame of reference for the affected leg in gait assessment in knee osteoarthritis (KO) fails due to compensatory mechanisms. Assessing the cyclical movements of the upper extremities in a frequency-controlled repetitive punching task may provide an alternative frame of reference in gait assessment in patients with KO. Eleven participants with unilateral KO and eleven healthy controls were asked to perform treadmill walking and repetitive punching. The KO group showed more predictable (p = 0.020) and less automatized (p = 0.007) movement behavior than controls during treadmill walking. During repetitive punching, the KO group showed a similar degree of predictability (p = 0.784) but relative more automatized movement behavior (p = 0.013). Thus, the predictability of the movement behavior of the upper extremities during repetitive punching seems unaffected by KO and could provide an alternative frame of reference in gait assessment in patients with KO.

Technical justification of the sectional construction of the pressure plate in the die-cutting press

It was stated that the die-cutting equipment belongs to the category of heavily loaded equipment because the drive overcomes significant technological resistances resulting from die-cutting of sweeps. Presses of the equipment are equipped with both wedge-lever mechanisms and eccentric ones to ensure cyclic vertical movement of the pressure plate. It is emphasized that automatic platens create a force loading in the die-cutting of sweeps of more than two hundred tons. A sectional construction of a pressure plate with an eccentric drive was suggested. Such a design of the pressure plate is designed to ensure consistent interaction of the tools of the die-cutting stamp with the sections of the cardboard cutting, to minimize the force loading of the drive. There were obtained values of the displacement invariant of all three sections of the pressure plate, the eccentrics of which are shifted in the angular direction. It was established that an increase in the cardboard thickness requires a similar change in the angular displacement of the eccentrics on the drive shafts in the adjacent sections. Further research on a test stand is planned.

Proof of Concept and Preliminary Validation of an Analytical Model of an Energy Dissipator for Tension Loads with Self-Centering Capacity

A novel energy dissipation device is proposed to protect structures against dynamic loads. A conceptual model of the device is presented, describing the fundamental components of its operation. This model has a linear elastic element and a frictional damper. The equilibrium equations that lead to the relationship that governs its behavior are proposed. A functional model of the device was built on a 3D printer with PLA filament. Experimental trials were carried out to characterize its elastic component and the coefficient of friction of the damping parts. Proofs of concept load-unload tests were also carried out on the device, subjecting it to cyclical movement sequences. The results of the first two types of tests allowed the parameters of the previously developed analytical model to be calibrated. The results of the load-unload tests were compared with the predictions of the analytical model using the calibrated parameters. Consistency was observed between the experimental and analytical results, demonstrating the basic attributes of the device: self-centering capacity, dissipation capacity and force proportional to the displacement demand. It is concluded that the proposed device has the potential to be used effectively in the protection of structures under dynamic loads.

Workers’ Bargaining Power and the Phillips Curve: A Micro–Macro Analysis

Abstract We use a general equilibrium model to show that a decrease in workers’ bargaining power amplifies the contribution to the output gap of adjustments along the extensive versus intensive margin of labour utilization. Under standard assumptions on the disutility of labour, this mechanism reduces the cyclical movements of inflation relative to those of the output gap. Micro-level evidence, based on a survey of Italian firms, provides support to the relationship between bargaining power and adjustments along the extensive margin versus the intensive one, as well as to attenuated price response when firms adjust labour input mainly through the extensive margin. A Bayesian estimation using Italian aggregate data for the samples 1970–1990 and 1991–2014 confirms that the decline in workers’ bargaining power has weakened the inflation–output gap relationship.

Is There a Business Cycle Effect on the Incidence of Dual Job Holding?

Abstract This paper examines the extent to which the incidence of dual job holding is cyclically sensitive in the context of hours constraints on a worker’s weekly labor supply to their main job. Random effects logit models of the probability of dual job holding are estimated separately for men and women for each of three mutually exclusive, hours-constrained regimes: overemployment, unconstrained hours, and underemployment. As measured by the deviation of each individual’s current regional unemployment rate from their time-averaged mean regional unemployment rate, transitory business cycle movements have no effect on the probability of dual job holding. However, a permanent/steady-state increase (decrease) in the local unemployment rate reduces (raises) the probability of dual job holding among hours-unconstrained workers for both males and females. Furthermore, permanent employment contracts reduce the likelihood of having two jobs.

Research on Multi-Body Collision Dynamics of Ball Cage Flexible Drill Pipe Considering Borehole Curvature

A ball cage flexible drill pipe is a new type of ultra-short-radius drilling tool, which consists of multiple flexible joints hinged together. During the drilling process, the flexible members will come into contact and wear, which reduces the efficiency of load transfer. The multi-body collision contact dynamics model was proposed to study the performance of the ball cage flexible drill pipe. The method considered the influence of the borehole curvature. The kinematic equations of the ball cage flexible drill pipe were established. The Lankarani–Nikravesh collisional contact model was used to characterize the normal contact force, and the Coulomb friction model was used to describe the tangential contact force. The multi-body motion state of the flexible drill pipe was simulated, the contact force distribution of the flexible drill pipe during the motion cycle was analyzed, and the influence of the borehole curvature radius on the size of the flexible joints and the contact force was studied. The results show that the running form of the ball cage flexible drill pipe shows a “folded” shape compared with the initial form; the contact force of different flexible joints is in a state of fluctuation; the normal contact force is much larger than the tangential contact force; the matching relationship between the borehole curvature and the length and radius of the flexible joints is derived, which provides criteria for the design of the flexible joints to ensure the reliability of the flexible drill pipe in large curvature borehole; the borehole curvature has an important influence on the collision contact force and load transfer efficiency of flexible drill pipe.

Movement-synchronized cerebellum rhythm coordinates multi-joint movements in young and elderly adults.

Rhythmic limb multi-joint movement like locomotion is controlled by intralimb coordination. Intralimb coordination changes entail immediate alterations in movement patterns and be related with cerebellum function. Synchronized cerebellum activity has known to modulate the frequency of walking, but not known the effect of only intralimb coordination. The purpose of this study was to reveal the effect of synchronized and unsynchronized cerebellum activity on the coordination of multi-joint movements of the unilateral leg in young and elderly people. To achieve our purpose, we applied synchronized and unsynchronized cerebellum transcranial alternating current stimulation during cyclic unilateral multi-joint movement by visual tracking task. The results showed that the reduction in comprehensive synchrony between targets and movements through trials had no significant differences under all stimulus conditions in young and elderly people. However, the reduction in variation of synchronization through trials was significantly smaller under the synchronized transcranial alternating current stimulation condition in both young and elderly groups. Variation of synchronization was remarkably reduced under the synchronized transcranial alternating current stimulation condition for the elderly group. This study showed that movement-synchronized cerebellum activity contributes to reducing fluctuations in movement synchrony by coordinating unilateral multi-joint movements. Moreover, this reduction was remarkable in the elderly group.

Swimming of the midge larva: Principles and tricks of locomotion at intermediate Reynolds number

At the millimeter scale and in the intermediate Reynolds number (Re) regime, the midge and mosquito larvae can reach swimming speeds of more than one body length per cycle performing a “figure eight” gait, in which their elongated bodies periodically bend nearly into circles and then fully unfold. To elucidate the propulsion mechanism of this cycle of motion, we conducted a three-dimensional (3D) numerical study, which investigates the hydrodynamics of undergoing the prescribed kinematics. We found novel propulsion mechanisms, such as modulating the body deformation rate to dynamically increase the maximum net propulsion force, using asymmetric kinematics to generate torque and the appropriate rotation, and controlling the radius of the curled body to manipulate the moment of inertia. The figure eight gait is found to achieve propulsion at a wide range of Re but is most effective at intermediate Re. The results were further validated experimentally, via the development of a soft millimeter-sized robot that can reach comparable speeds using the figure eight gait.

The Use of Amniotic membrane in Carpal Tunnel Syndrom, a Cadaver Study

Introduction: Carpal tunnel syndrome (CTS) is the most common peripheral nerve entrapment syndrome worldwide. Even after surgery in 2-25% of patients symptoms persist. Most commonly the carpal tunnel was not completely released. In the other cases perineural scarring is causing recurrent compression of the nerve. The literature states different treatment options including “nerve wraps,” made out of autologous veins or synthetic materials, to protect the nerve from scarring. The human amniotic membrane (HAM) has been proven to express anti-inflammatory and anti-fibrotic properties, without causing a immune reaction. In a rat model it has been shown that nerve gliding could be improved by the application of HAM after introducing a fibrotic scar. The application of HAM in CTS and it´s possible influence on nerve gliding has been examined. Materials and Methods: Fourteen (7 female, 7 male) fresh body donors were dissected. The carpal tunnel was released and a nerve wrap out of HAM was sutured around the median nerve with continuous stitches (7-0). The position of the HAM was measured and the skin was closed (3-0) Next the arm was moved according to a protocol, creating a largest possible movement of the nerve. The position was again evaluated. This was done after 25, 50, 100, 150, 200, 250 movement cycles. Results: The HAM on the median nerve did not change its position significantly between the timepoints. From the beginning to the end of the movements it contracted and reduced its size to about 92% of its starting length. The evaluation of the gliding properties is still in progress. Conclusion: The HAM showed to stay in place and only minor contract on both ends in the carpal tunnel. The application of HAM in the carpal tunnel worked well without any complications and can be seen as feasible treatment method for recurrent carpal tunnel syndrome.

Effect of non-specific neck pain on the path of the instantaneous axis of rotation of the neck during its flexion-extension movement

Non-specific neck pain is a common musculoskeletal disorder with a high prevalence and involves impaired joint movement pattern. Therefore, this study aimed to compare the trajectory of the instantaneous axis of rotation(IAR) in flexion-extension movements of the neck between people with and without nonspecific neck pain, using functional data analysis techniques. Furthermore, possible relationships between neck kinematics and perceived pain and disability were explored.Seventy-three volunteers participated in this cross-sectional study. They were allocated in a non-specific pain group (PG, n = 28) and a control group (CG, n = 45). A cyclic flexion-extension movement was assessed by a video photogrammetry system and numerical and functional variables were computed to analyze IAR trajectory during movement. Moreover, to explore possible relationships of these variables with pain and neck disability, a visual analogue scale (VAS) and the neck disability index (NDI) were used.The instantaneous axis of rotation trajectory during the flexion-extension cyclic movement described a path like Greek letter rho both in the CG and the PG, but this trajectory was shorter and displaced upward in the PG, compared to the CG. A reduction of the displacement range and a rise in the vertical position of the IAR were related to VAS and NDI scores.Non-specific neck pain is associated with a higher location of the instantaneous axis of rotation and a decrease in length of the path traveled during the flexion-extension movement. This study contributes to a better description of neck movement in people with non-specific neck pain, which would help to plan an individualized treatment.

Crack formation of camshaft castings: Hot tearing susceptibility and root causes

As a widely used cyclical motion component, the camshaft plays a key role in the accuracy and stability of the whole machine. Micro hot cracks in the camshaft casting process are an important cause of failure in subsequent machining and operation. In this paper, the hot tearing susceptibility of the camshaft in the casting process was studied using the alloy composition (carbon equivalent and Mn/S ratio) and mold preheating temperature. The formation mechanism of the hot tear source was analyzed through the microscopic morphology of the fracture-sensitive cross-section. Using the improved Clyne-Davies model and the newly proposed hot tearing susceptibility (HTS) model, the results show that as the carbon equivalent and Mn/S ratio increase, the hot tearing susceptibility of the camshaft first decreases and then increases. The hot tearing tendency of the casting can be reduced by appropriately increasing the mold preheating temperature. The microscopic morphology indicates that the initiation and propagation of the crack source are caused by the excessively serious non-equilibrium solidification of the camshaft metal fluid. Finally, potential countermeasures are proposed to decrease micro hot cracks in camshaft castings, including the adjustment of alloy composition, optimization of casting process parameters, and improvement of system solidification conditions.

Silicone breast implant rupture is more prevalent in the dominant limb side: A retrospective cohort study

Breast implant rupture is associated with multiple risk factors such as implant age, manufacturer, and a history of trauma to the breast. However, the exact mechanism of breast implant rupture remains unclear. We hypothesize that repetitive minor mechanical forces on the implant collectively play a significant role in the cascade that eventually leads to its rupture. Therefore, we expect a more significant cumulative effect on the breast implant in the dominant upper limb side. Thus, we aim to ascertain whether laterality in silicone breast implant rupture is associated with the dominant upper limb. A retrospective cohort study was performed on patients with silicone breast implants who underwent an elective breast implant removal or exchange. All patients had breast augmentations for cosmetic reasons. We collected data on implant rupture laterality and limb dominance together with known risk factors like patient age, implant age, implant pocket, and implant volume. A total of 154 patients with unilateral implant rupture were included in the study. Among patients with a dominant right limb (n=133), an ipsilateral rupture was found in 77 patients (58%) (p=0.036), while in patients with a left dominant limb (n=21), an ipsilateral rupture was found in 14 patients (67%), (p=0.036). The dominant limb was a significant risk factor for ipsilateral breast implant rupture. The prevailing theory that cyclic envelope movement carries an increased rupture risk is reinforced in this study. Extensive prospective studies are needed to clarify risk factors for implant rupture further.

Comparing the effects of dynamic and holding isometric contractions on cardiovascular, perceptual, and near-infrared spectroscopy parameters: A pilot study.

The aim of this pilot study was to assess the effect of muscle contraction type on SmO2 during a dynamic contraction protocol (DYN) and a holding isometric contraction protocol (ISO) in the back squat exercise. Ten voluntary participants (age: 26.6 ± 5.0 years, height: 176.8 ± 8.0 cm, body mass: 76.7 ± 8.1 kg, and one-repetition maximum (1RM): 112.0 ± 33.1 kg) with back squat experience were recruited. The DYN consisted of 3 sets of 16 repetitions at 50% of 1RM (56.0 ± 17.4 kg), with a 120-second rest interval between sets and 2 seconds per movement cycle. The ISO consisted of 3 sets of 1 isometric contraction with the same weight and duration as the DYN (32 seconds). Through near-infrared spectroscopy (NIRS) in the vastus lateralis (VL), soleus (SL), longissimus (LG), and semitendinosus (ST) muscles, the minimum SmO2 (SmO2 min), mean SmO2 (SmO2 avg), percent change from baseline (SmO2 Δdeoxy) and time to recovery 50% of baseline value (t SmO2 50%reoxy) were determined. No changes in SmO2 avg were found in the VL, LG, and ST muscles, however the SL muscle had lower values in DYN, in the 1st set (p = 0.002) and in the 2nd set (p = 0.044). In terms of SmO2 min and ΔSmO2 deoxy, only the SL muscle showed differences (p≤0.05) and lower values in the DYN compared to ISO regardless of the set. The t SmO2 50%reoxy was higher in the VL muscle after ISO, only in the 3rd set. These preliminary data suggested that varying the type of muscle contraction in back squat with the same load and exercise time resulted in a lower SmO2 min in the SL muscle in DYN, most likely because of a higher demand for specialized muscle activation, indicating a larger oxygen supply-consumption gap.