Values In Time Research Articles

Lightning Potential Index and its spatial and temporal characteristics in COSMO NWP model

Among severe meteorological hazards, lightning is considered one of the most dangerous; however, its forecast is difficult because the formation of lightning is the result of processes in the clouds that are difficult to model accurately. In this study, we predict lightning activity using the Lightning Potential Index (LPI), which is quite often used to determine areas with expected lightning activity, and analyse its spatial and temporal characteristics. Specifically, we performed simulations of LPI (15 min values) using the COSMO NWP model for 10 selected thunderstorm events of 2018 in Central Europe. We used the model runs with 1- and 2-moment cloud microphysics and with a lead time of 12 h presented in our previous study, while in this study we performed deeper analyses and verified the 15 min LPI values in space and time using ground-based observations of lightning. Our results showed that 2-moment cloud microphysics provide better LPI forecasts which confirms the suggestion of our previous study. The distribution of predicted lightning activity related to the model orography was examined and found consistent with the occurrence of recorded lightning discharges. The Fraction Skill Score analysis revealed that for 2-moment cloud microphysics a skilful forecast was reached at smaller scales than for 1-moment microphysics, namely at scales around 90 km for LPI thresholds 30, 40 and 50 Jkg−1. We also evaluated the forecasts using a performance diagram, which in contrast to other results did not confirm that forecasts using 2-moment cloud microphysical scheme were more accurate than forecasts using 1-moment cloud microphysical scheme. Spatial verification of LPI showed that depending on the distance limit (15–90 km) and the LPI threshold (from LPI > 0 Jkg−1 to LPI > 50 Jkg−1), the probability of lightning discharge occurrence was ca 30–90% and the proportion of successfully predicted lightning discharges reached up to 77%. We consider this result satisfying, though the spatial verification remains challenging. Contrary to spatial verification of LPI, the temporal verification of LPI turned out to be even more efficient (in 70% of cases the time difference between the defined beginnings of forecasted and detected lightning activity was maximum 45 min). In future, we plan to perform lightning prediction in another NWP model, namely the ICON NWP model. We also plan to analyse more thunderstorm events.

Optimistic NAUTILUS navigator for multiobjective optimization with costly function evaluations

We introduce novel concepts to solve multiobjective optimization problems involving (computationally) expensive function evaluations and propose a new interactive method called O-NAUTILUS. It combines ideas of trade-off free search and navigation (where a decision maker sees changes in objective function values in real time) and extends the NAUTILUS Navigator method to surrogate-assisted optimization. Importantly, it utilizes uncertainty quantification from surrogate models like Kriging or properties like Lipschitz continuity to approximate a so-called optimistic Pareto optimal set. This enables the decision maker to search in unexplored parts of the Pareto optimal set and requires a small amount of expensive function evaluations. We share the implementation of O-NAUTILUS as open source code. Thanks to its graphical user interface, a decision maker can see in real time how the preferences provided affect the direction of the search. We demonstrate the potential and benefits of O-NAUTILUS with a problem related to the design of vehicles.

Modeling leaf color dynamics of winter wheat in relation to growth stages and nitrogen rates

The objective of this work was to develop a model for simulating the leaf color dynamics of winter wheat in relation to crop growth stages and leaf positions under different nitrogen (N) rates. RGB (red, green and blue) data of each main stem leaf were collected throughout two crop growing seasons for two winter wheat cultivars under different N rates. A color model for simulating the leaf color dynamics of winter wheat was developed using the collected RGB values. The results indicated that leaf color changes went through three distinct stages, including early development stage (ES), early maturity stage (MS) and early senescence stage (SS), with respective color characteristics of light green, dark green and yellow for the three stages. In the ES stage, the R and G colors gradually decreased from their initial values to steady values, but the B value generally remained unchanged. RGB values remained steady in the MS, but all three gradually increased to steady values in the SS. Different linear functions were used to simulate the dynamics of RGB values in time and space. A cultivar parameter of leaf color matrix (MRGB) and a nitrogen impact factor (FN) were added to the color model to quantify their respective effects. The model was validated with an independent experimental dataset. RMSEs (root mean square errors) between the observed and simulated RGB values ranged between 7.0 and 10.0, and relative RMSEs (RRMSEs) ranged between 7 and 9%. In addition, the model was used to render wheat leaves in three-dimensional space (3D). The 3D visualizations of leaves were in good agreement with the observed leaf color dynamics in winter wheat. The developed color model could provide a solid foundation for simulating dynamic crop growth and development in space and time.

Managing company value in times of COVID-19 turbulences: Winners and losers in Central Europe

This research adds to the growing literature on impact of the COVID-19 global turmoil on corporate financial performance. Changes in company value are continuous market processes. However, the pandemic has triggered many shock changes, including unprecedented turbulences in most business mechanisms. Our research provides empirical assessment of the market process of value migration across industries in Central Europe in several dimensions. The estimates of market value added and synthetic measure of value migration show substantial differences between industries. The study provides a classification of business designs by development stages and details significant changes in operating performance in response to the health and economic turmoil. Our findings on differences in industries’ vulnerability to shock changes have important implications for managers, shareholders, lenders, and other company stakeholders.

The World Health Organization: Following the Values in Unstable Times

The aim of this article is to show the environment in which the World Health Organization operates. The article discusses the basic issues related to the global health care system, and then the statutory aims and purposes of the Organization. The last part analyses the indicated goals in the context of the realities, primarily the political ones, paying attention to the coronavirus pandemic, which undoubtedly has affected the functioning of Organization. The article shows various types of problems that the WHO encounters in the course of its activity, which illustrates the complexity and comprehensiveness of the phenomena that occur in the area of operation of international organisations.

Effects of Hydrolysed Collagen Associated or Not with Physical Agents on Tissue and Muscle Flaccidity—Firmez Method: Case Study

The combination of therapies may be the promising future for the treatment of esthetic alterations more efficiently and in less time, in order to obtain an excellent result. Our objective was to evaluate the effectiveness of hydrolysed collagen associated with radiofrequency and electrostimulation in the treatment of flaccidity in the abdominal and gluteal regions. The sample consisted of 6 women, evaluated through evaluation protocols, questionnaires, dynamometry, ultrasound exams, and histological analysis. The volunteers were distributed into three subgroups: hydrolysed collagen group (G-1), radiofrequency + hydrolysed collagen group (G-2) and radiofrequency + hydrolysed collagen + electrostimulation group (G-3). The ultrasound analysis of the abdominal muscles showed an increase in muscle thickness in all groups, but not significant (p > 0.05). The histological analysis showed an evident increase in type I collagen in groups G-2 and G-3, with proliferating cells (Ki67+). The results of dynamometry showed significant values in different times (p < 0.05). There was a significant result in the infraumbilical perimetry analysis, when compared between the groups with 30 days (p = 0.03) and with 60 days (p = 0.04). All participants rated the treatment positively. The use of combined therapies has shown superior results for the treatment of abdominal and gluteal flaccidity when compared with its isolated use, being the combination of therapies important in the treatment of flaccidity.

Heart Rate Variability Metrics from Commercial Devices Predicts Strength and Cardiovascular Performance in a Military Cohort

Heart rate variability (HRV) has become popular for assessing improvements in physical fitness, performance, and recovery. The purpose of this study was to assess the ability of HRV metrics to predict strength and cardiovascular performance in a military cohort using data obtained from commercial off-the-shelf (COTS) wearables. (1) Methods: Twenty-four active-duty military personnel (17 males; 7 females), ranging from age 23 to 41 (32.70 ± 4.65), were equipped with a Whoop Strap 3.0, a Garmin Fenix 5, and an Omegawave during a 12-week exercise intervention study. For this experiment researchers focused solely on HRV metrics obtained on scheduled “Gameday” competitions that occurred periodically during the intervention and contained a battery for strength, power, and cardiovascular performance tests. (2) Statistical Analysis: HRV metrics fitted with linear mixed models and applied to a composite strength variable derived following interrogation of performance tests with principal component analysis (PCA). Akaike’s information criterion (AIC) was also used to compare cardiovascular and strength metrics. (3) Results: Results indicated that standard deviation of NN intervals (SDNN)] obtained from Omegawave was the best overall predictor of performance (AIC > 5.00). (4) Conclusion: Our analyses demonstrated that traditional metrics obtained with the Omegawave were the best performance predictors. HRV measured by Omegawave immediately prior to Gameday assessment was inversely related with strength performance, suggesting that a lower HRV was associated with higher performance (p = 0.002). These findings demonstrate the potential influence of timing and raw values utilized on HRV interpretation to predict strength and cardiovascular performance.

Melatonin, circadian rhythms and glaucoma: current perspective.

Melatonin, circadian rhythms and glaucoma: current perspective.

Overapproximation of the Number of Active Timers in Timed-Arc Petri Nets Using DP-Systems

Timed-arcs Petri nets are a time extension of Petri nets that allows assigning clocks to tokens. System of dynamic points on a metric graph (DP-systems) is another dynamical model that is studied in discrete geometry dynamics; DP-system combines continuous time and discrete branching events and used, for example, in study of localized Gaussian wave packets scattering on thin structures. In recent works, asymptotic estimates of the growth of the number of points in dynamic systems on metric graphs were obtained. In this paper, we provide a mean to overapproximate the number of different values of timers for a subclass of timed-arc Petri nets by constructing a system of dynamic points on a metric graph and prove overapproximation of the number of timer values by the number of points in the system of dynamic points.

Cross Layer MAC Protocol for a Peer Conscious Opportunistic Network Coded Cooperation System

This paper presents a peer conscious opportunistic network coded cooperation (PC-O-NCC) system that exploits multi-user diversity (MUD) gain in a simple network coded cooperation (NCC) based network. It prioritizes sources with better channel conditions by granting them earlier access than the other competing nodes unlike the prevalent time division multiple access (TDMA) technique used widely in any NCC network. This improves the outage performance of the overall system. To prioritise sources with better channel conditions, a novel timer-based MAC protocol is proposed. The proposed protocol is designed such that it aims to reduce collisions by taking the network load into account along with channel conditions while generating the timer values. It also minimizes the power consumption in performing clear channel assessment (CCA) by sources which is a costly affair for battery-operated devices. The simulation results show that the proposed algorithm improves the outage performance while keeping the latency to a minimum value. The improvement in the outage performance can prove to be important in taking key decisions which becomes crucial in disaster management, drone assisted scenarios or intelligent transportation systems.

The Times Value of the Spirit of “Two Bombs and One Star” and Reflection on the Path to Carry Forward in the New Era

The Times Value of the Spirit of “Two Bombs and One Star” and Reflection on the Path to Carry Forward in the New Era

Actuation Timing Perception of a Powered Ankle Exoskeleton and Its Associated Ankle Angle Changes During Walking.

Robotic ankle exoskeletons have the potential to extend human ability, and actuation timing serves as one of the critical parameters in its controller design. While many experiments have investigated the optimal actuation timing values to achieve different objective functions (e.g. minimizing metabolic cost), studies on users' perception of control parameters are gaining interest as it gives information on people's comfort, coordination, and trust in using devices, as well as providing foundations on how the sensorimotor system detects the exoskeleton behavior changes. The purpose of this study was to evaluate people's sensitivity to changes in exoskeleton actuation timing and its associated exoskeleton ankle angle changes during walking. Participants (n =15) with little or no prior experience with ankle exoskeletons were recruited and performed a psychophysical experiment to characterize their just-noticeable difference (JND) thresholds for actuation timing. Participants wore a bilateral active ankle exoskeleton and compared pairs of torque profiles with different actuation timings and low peak torque (0.225 Nm/kg) while walking on the treadmill. The mean timing JND across participants was 2.8±0.6% stride period. Individuals exhibited different sensitivity towards actuation timing, and their associated exoskeleton ankle angle changes also varied. The variance in ankle angle changes might be explained by their differences in ankle stiffness and different ankle torques provided during walking. The results provide insights into how people perceive the changes in exoskeleton control parameters and show individual differences in exoskeleton usage. The actuation timing JND found in this study can also help determine the necessary controller precision.

Optimum control of a flexible single link manipulator with Artificial Bee Colony Algorithm

This paper presents a stable control for a single link flexible manipulator. The flexible manipulator is considered as Euler–Bernoulli beam, and its dynamic model is developed based on assumed mode method. Position and vibration control are realised with a single controller as motor torque. The controller has three parameters that must be selected. In this paper, the main motivation is to find the suitable parameter values to generate optimum torque values in every sampling time. In order to achieve this goal, Artificial Bee Colony Algorithm is performed, and the controller parameters are optimised simultaneously in every sampling period. Simulations verify that the manipulator achieves the position control objective, and the vibration is suppressed simultaneously even with different payloads with the proposed optimisation method.

Development of Force Sensor System Based on Tri-Axial Fiber Bragg Grating with Flexure Structure.

Fiber Bragg grating (FBG) sensors have an advantage over optical sensors in that they are lightweight, easy to terminate, and have a high flexibility and a low cost. Additionally, FBG is highly sensitive to strain and temperature, which is why it has been used in FBG force sensor systems for cardiac catheterization. When manually inserting the catheter, the physician should sense the force at the catheter tip under the limitation of power (<0.5 N). The FBG force sensor can be optimal for a catheter as it can be small, low-cost, easy to manufacture, free of electromagnetic interference, and is materially biocompatible with humans. In this study, FBG fibers mounted on two different flexure structures were designed and simulated using ANSYS simulation software to verify their sensitivity and durability for use in a catheter tip. The selected flexure was combined with three FBGs and an interrogator to obtain the wavelength signals. To obtain a calibration curve, the FBG sensor obtained data on the change in wavelength with force at a high resolution of 0.01 N within the 0.1–0.5 N range. The calibration curve was used in the force sensor system by the LabVIEW program to measure the unknown force values in real time.

Are commuter train timetables consistent with passengers’ valuations of waiting times and in-vehicle crowding?

Social cost-benefit analysis is often used to analyse transport investments, and can also be used for transport operation planning and capacity allocation. If it is to be used for resolving capacity conflicts, however, it is important to know whether transit agencies' timetable requests are consistent with the cost-benefit framework, which is based on passenger preferences. We show how a public transport agency's implicit valuations of waiting time and crowding can be estimated by analysing timetables, apply the method to commuter train timetables in Stockholm, and compare the implicit valuations to the corresponding passenger valuations in the official Swedish cost-benefit analysis guidelines. The results suggest that the agency puts a slightly lower value on waiting time and crowding than the passenger valuations codified in the official guidelines. We discuss possible reasons for this and implications for using cost-benefit analysis for capacity allocation. We also find that optimal frequencies are more sensitive to the waiting time valuation than to that of crowding.

Acculturation discrepancy and mental health associations among Hispanic childhood cancer survivors and their parents.

Acculturation discrepancy occurs when the rate of host culture acquisition and/or heritage culture retention between non-native parents and their children diverges. The resulting conflict may exacerbate mental health conditions in already vulnerable populations. The present study examined discrepancies between Hispanic and Anglo-American acculturation, as two separate constructs, and mental health symptomology in Hispanic childhood cancer survivors (HCCS) and their parents. Participants were 68 matched parent-child dyads (HCCS (Mage =19.4 (2.77)years., 50.0% female); and parent (Mage =46.3 (6.07)years., 89.7% female)). Study variables were HCCS posttraumatic-growth (PTG) and quality-of-life (PedsQL); parent posttraumatic stress (PTSD); and parent/HCCS depressive symptoms (CESD) and acculturation orientations. Discrepancy was calculated as the dyadic difference between like acculturation measures. After controlling for covariates, Hispanic acculturation discrepancy and HCCS psychosocial health (a subset of PedsQL) was negatively correlated (r=-0.26, p<0.5); while Anglo-American acculturation discrepancy was positively associated with HCCS PTG (r=0.34, p<0.01) and overall PedsQL (r=0.24, p<0.05), and moderated the relationship between parent CESD and HCCS PedsQL. The findings suggest that the two acculturation discrepancy constructs have opposite effects. HCCS losing their heritage culture while their parents simultaneously retain it appears to be a deleterious process; whereas, HCCS learning the US culture more rapidly than parents may have protective benefits. This study has important implications for mental health interventions among HCCS. Findings should be used to inform the survivorship clinical community of the value of acculturation timing and parent/child discrepancy.

An Improved Blade Vibration Parameter Identification Method considering Tip Clearance Variation

Blade tip timing (BTT) technology is the most effective means for real-time monitoring of blade vibration. Accurately extracting the time of blade tip reaching the sensors is the key to ensure the accuracy of the BTT system. The tip clearance changes due to various complex forces during high-speed rotation. The traditional BTT signal extraction method does not consider the influence of tip clearance change on timing accuracy and introduces large timing errors. To solve this problem, a quadratic curve fitting timing method was proposed. In addition, based on the measurement principle of the eddy current sensors, the relationship among the output voltage of the eddy current sensor, tip clearance, and the blade cutting magnetic line angle was calibrated. A multisensor vibration parameter identification algorithm based on arbitrary angular distribution was introduced. Finally, the experiments were conducted to prove the effectiveness of the proposed method. The results show that in the range of 0.4 to 1.05 mm tip clearance change, the maximum absolute error of the timing values calculated by the proposed method is 26.0359 us, which is much lower than the calculated error of 203.7459 us when using the traditional timing method. When the tip clearance changed, the constant speed synchronous vibration parameters of No. 0 blade were identified. The average value of the vibration amplitude is 1.0881 mm. Compared with the identification results without changing tip clearance, the average value error of the vibration amplitude is 0.0017 mm. It is proved that within the blade tip clearance variation of 0.4 to 0.9 mm, the timing values obtained by the proposed timing method can accurately identify the vibration parameters of the blade.

Does urea modify microheterogeneous nature of ionic amide deep eutectics? Clues from non-reactive and reactive solute-centered dynamics

The impact of urea on the microheterogeneous nature of acetamide + LiNO3 deep eutectic solvents (DESs) was investigated via following the viscosity coupling of the average timescales of solute rotation, solvation and cis–trans isomerization reaction occurring in such media. Picosecond resolved fluorescence measurements were carried out to access these average relaxation timescales and the solutes employed were the non-reactive probe, coumarin153 (C153), and a reactive probe, trans- 2-[4′-(Dimethylamino) styryl]benzothiazole (DMASBT). DMASBT undergoes fast cis–trans isomerization reaction upon photo-excitation. The coupling to the solution viscosity (η) of the experimentally determined average timescales was then analyzed via the relation, 〈τx〉∝ηp, x denoting rotation, solvation or reaction, and a fractional p considered as solution microheterogeneity reflector. A comparison of the findings between the urea containing and non-urea ionic DESs revealed that addition of urea did not alter the p value for C153 rotation and DMASBT reaction times, while the C153 average solvation times showed a stronger decoupling. This stronger decoupling has been ascribed to the faster rate of solvation upon addition of urea via the participation of the amide group through the collective H-bond excitations. Addition of electrolyte at a fixed amide concentration, on the other hand, makes the fractional viscosity dependence more pronounced for both solvation and rotational dynamics, although the viscosity coupling (p value) of isomerization reaction timescale remains unchanged. DMASBT reveals, through steady state fluorescence measurements, stronger spatial heterogeneity in these solutions than that by C153, and DMASBT better senses the urea or electrolyte induced modulation of spatial heterogeneity.

Dynamical friction from scalar dark matter in the relativistic regime

Light bosonic scalars (e.g. axions) may form clouds around black holes via superradiant instabilities, or via accretion if they form some component of the dark matter. It has been suggested that their presence may lead to a distinctive dephasing of the gravitational wave signal when a small compact object spirals into a larger black hole. Motivated by this, we study numerically the dynamical friction force on a black hole moving at relativistic velocities in a background scalar field with an asymptotically homogeneous energy density. We show that the relativistic scaling is analogous to that found for supersonic collisional fluids, assuming an approximate expression for the pressure correction which depends on the velocity and scalar mass. While we focus on a complex scalar field, our results confirm the expectation that real scalars would exert a force which oscillates between positive and negative values in time with a frequency set by the scalar mass. The complex field describes the time averaged value of this force, but in a real scalar the rapid force oscillations could in principle leave an imprint on the trajectory. The approximation we obtain can be used to inform estimates of dephasing in the final stages of an extreme mass ratio inspiral.

A fast neighborhood search scheme for identical parallel machine scheduling problems under general learning curves

There is a limited number of results concerning fast and efficient solution algorithms for scheduling problems with general learning models. Therefore, we develop a fast insert neighborhood search (FINS) for a group of identical parallel machine scheduling problems with general learning curves under the following minimization objectives: the maximum completion time (makespan) and the maximum lateness. Our fast search scheme allows to calculate criterion values in a constant time per solution in a neighborhood. The application is presented on the basis of Nawaz–Enscore–Ham’s method (NEH), iterative local search, tabu search, particle swarm optimization and hybrid simulated annealing — tabu search algorithms, where the efficiency of their standard implementations are compared to their versions enhanced by our fast insert neighborhood search. The computational experiments confirm the theoretical analysis that our method essentially overwhelms the well known approaches. The metaheuristics augmented by our FINS are about 120 times faster than their standard versions and improve the criterion values by up to 25% for analyzed instances with 100–800 jobs and 5–80 machines.