Full Step Research Articles

Outcomes Vary by Pre-Operative Physical Activity Levels in Total Knee Arthroplasty Patients.

Physical activity (PA) is suggested to reduce osteoarthritis pain; however, it may be avoided by patients requiring arthroplasty. Our goal was to investigate objective and patient-reported outcomes as a function of pre-operative PA levels in patients undergoing total knee arthroplasty (TKA). A total of 1941 patients enrolled in a multicenter prospective cohort study investigating a smartphone-based care management platform for self-directed rehabilitation underwent TKA and were included in the analysis. Activity was categorized based on the cohort's step count quartiles into low, moderate, and high pre-operative PA. Pre-operative and post-operative pain, EQ5D5L, KOOS JR, and step counts were compared by ANOVA according to activity group. Pre-operative pain scores increased with the decreasing activity level (all, p < 0.05) and were most improved post-operatively in the low PA group. High PA patients demonstrated the smallest improvements in EQ-5D-5L and KOOS JR. Low and moderate PA patients increased physical activity by three months, reaching 176% and 104% of pre-operative steps; high PA patients did not return to full step counts by one year post-operatively. Patients undergoing TKA who present with higher levels of physical activity report lower levels of pain and higher function pre-operatively but appreciate less improvement up to one year post-operatively. These results may be helpful in appropriate counseling of patient expectations before TKA.

A compact high resolution semi-variable mesh exponential finite difference method for non-linear boundary value problems of elliptic nature

In this research an original exponential approximation of second accuracy in y- and third accuracy in x-axis employing full step discretization has been designed for solving 2D non-linear partial differential equation of elliptic nature in a rectangular domain. We adopted non-constant grid spacing in x -axis and constant grid spacing in y -axis in numerical computation of convection-diffusion equation where convection term dominates. An exhaustive error behaviour of the technique has been analysed. Non-linear elliptic equations are computed using this method. Lastly, proposed idea is scrutinized on simulations of physical repute with emphasis on convection-diffusion equation articulating the efficacy of the technique.

ANALYZING A THREE HUNDRED TEETH BI-PHASE HYBRID STEPPER MOTOR WITH DIFFERENT NUMBERS OF POLE PAIRS

The paper presents numerical models of a bi-phase, 0.3° full step hybrid stepper motor (HSM), with 16, 24, 32, 40, and, respectively, 48 poles in the stator. For the motor to move with a constant step angle, the stator and the rotor teeth must be shifted against each other with an angle of zero, 90, 180, and 270 electric degrees for each four consecutive stator poles. Due to this, bi-phase steppers with the number of poles in the stator different than eight are hardly seen. Therefore, to allow the construction of HSMs with different numbers of poles, some of the stator poles must be shifted from their symmetrical position. The five topologies' HSM detent and holding torque characteristics and their geometrical and constructive differences are presented. The Finite Element Method (FEM) based models are developed using the professional software COMSOL Multiphysics.

An Optimization Scheme and Circuit for Driving a Stepper Motor with the Index Control Mode

An optimized control scheme for driving a stepper motor with the index control mode is proposed and analyzed in this paper to control the stepper motor more accurately and effectively. Based on the built-in five-digit digital-to-analog signal converter (DAC), six stepper motor operating modes, namely 1/32 micro steps, 1/16 micro steps, 1/8 micro steps, 1/4 step, 1/2 step, and full step, can be selected. Only four control ports are required for switching of operating mode and motor steering. The simulation results show the optimized circuit can output accurate current signals to control the stepper motor.

Multiscale Modelling of Solid Oxide Cells Validated on Electrochemical Impedance Spectra and Polarization Curves

Solid Oxide Cells (SOCs) are high temperature energy-conversion devices which have attracted a growing interest in the recent years. Indeed, this technology presents a high efficiency and a good reversibility in fuel cell (SOFC) and electrolysis (SOEC) modes. Thanks to its flexibility, SOCs can offer technical solutions for the development of a clean hydrogen economy. Nevertheless, SOCs durability is still insufficient for large scale commercialization. Therefore, it is still required to improve the SOCs lifetime by maintaining high performances. For this purpose, it is necessary to better understand the impact of global operating conditions on the local processes taking place in the cell components. Besides, the role of the electrode microstructure on the reaction mechanism is still not precisely understood. From this point of view, the modelling can be an efficient tool to unravel and better analyze all the microscopic processes involved in the cell operation.In this context, a physical-based model has been proposed to investigate the impact of operating conditions on the electrodes reaction mechanisms and cell performances. This model takes into account (i) a 3D representation of the electrode microstructure [1], (ii) a description of the reaction mechanisms in full elementary steps [2,3] and (iii) the SOC geometry with the gas flow configuration [4,5]. This multiscale model has been developed considering a typical cell composed of a dense electrolyte in Y0.148Zr0.852O1.926 (8YSZ) sandwiched between an O2 electrode in La0.6Sr0.4Co0.2Fe0.8O3- d-Ce0.8Gd0.2O2-δ (LSCF-GDC) and an H2 electrode made of Ni and YSZ (Ni-YSZ). The model has been validated using a specific experimental setup which was developed to measure the local polarization curves along the cell length. For this purpose, a specific design of the interconnect has been proposed in order to probe the local current density on the standard studied cells (Fig. 1a) [6]. It has been found that the model is able to reproduce accurately the global and local polarizations curves in SOFC and SOEC modes (Fig. 1a and 1b). The stationary model has been also extended to compute electrochemical impedance spectra by keeping the full description of the reaction mechanisms in elementary steps. This dynamic model, which is able to compute the impedance diagrams at Open Circuit Voltage (OCV) and under polarization, has been compared to the experimental data. As shown in Fig. 1c and 1d, a reasonable agreement has been found between the measurements and the simulations without any fitting.The validated stationary and dynamic model has been used to analyze the cell operation in electrolysis and fuel cell modes. The activated reaction pathways associated with the elementary steps in the active layers have been investigated depending on the position along the cell length. The different contributions arising in the impedance spectra have been also identified and discussed.

Interior-point algorithm for symmetric cone horizontal linear complementarity problems based on a new class of algebraically equivalent transformations

AbstractWe generalize a primal-dual interior-point algorithm (IPA) proposed recently in (Illés T, Rigó PR, Török R Unified approach of primal-dual interior-point algorithms for a new class of AET functions, 2022) to $$P_*(\kappa )$$ P ∗ ( κ ) -horizontal linear complementarity problems (LCPs) over Cartesian product of symmetric cones. The algorithm is based on the algebraic equivalent transformation (AET) technique with a new class of AET functions. The new class is a modification of the class of AET functions proposed in (Illés T, Rigó PR, Török R Unified approach of primal-dual interior-point algorithms for a new class of AET functions, 2022) where only two conditions are used as opposed to three used in (Illés T, Rigó PR, Török R Unified approach of primal-dual interior-point algorithms for a new class of AET functions, 2022). Furthermore, the algorithm is a feasible algorithm that uses full Nesterov-Todd steps, hence, no calculation of step-size is necessary. Nevertheless, we prove that the proposed IPA has the iteration bound that matches the best known iteration bound for IPAs solving these types of problems.

Catalytic Conversion of H2S to H2: Challenges and Catalyst Limitations

H2S, a highly toxic chemical, is produced in massive quantities worldwide as a byproduct. Environmental regulations require >99% sulfur recovery, which is currently met using sulfur recovery units based on the Claus process, where H2S is converted to sulfur and water. Ideally, hydrogen in H2S is recovered as H2. Despite much effort to achieve this objective, especially in thermal catalysis, an industrial application remains distant. A fundamental factor is the lack of an effective catalyst. In this work, we employ density functional theory to illustrate the main limitations in existing catalysts. We use pure metals to explain this by studying the full elementary steps in H2S decomposition. We find that many catalysts, though capable of decomposing H2S, are limited due to sulfur poisoning. We conclude by outlining the ideal properties of a catalyst for this process.

Generalized Gearhart-Koshy acceleration for the Kaczmarz method

The Kaczmarz method is an iterative numerical method for solving large and sparse rectangular systems of linear equations. Gearhart, Koshy and Tam have developed an acceleration technique for the Kaczmarz method that minimizes the distance to the desired solution in the direction of a full Kaczmarz step. The present paper generalizes this technique to an acceleration scheme that minimizes the Euclidean norm error over an affine subspace spanned by a number of previous iterates and one additional cycle of the Kaczmarz method. The key challenge is to find a formulation in which all parameters of the least-squares problem defining the unique minimizer are known, and to solve this problem efficiently. When only a single Kaczmarz cycle is considered, the proposed affine search is more effective than the Gearhart-Koshy/Tam line-search, which in turn is more effective than the underlying Kaczmarz method. A numerical experiment from the context of computerized tomography suggests that the proposed affine search has the potential to outperform the the Gearhart-Koshy/Tam line-search and the underlying Kaczmarz method in terms of the computational cost that is needed to achieve a given error tolerance.

Atomic Layer Deposition ZnO-Enhanced Negative Electrode for Lithium-Ion Battery: Understanding of Conversion/Alloying Reaction via 7Li Solid State NMR Spectroscopy

Understanding the mechanism for capacity delivery in conversion/alloying materials (CAM) electrodes, such as ZnO, in lithium-ion batteries (LIBs) requires careful investigation of the electrochemical reactions. Here, we used magic angle spinning (MAS at 60 kHz) 7Li nuclear magnetic resonance (NMR) as a sensitive analytical means to probe the reactions occurring between electrode materials and Li+ ions. The ZnO nanolayer generated on carbon substrate by atomic layer deposition (ALD) enhanced the cyclic capacity of half cell LIB up to 40%. 7Li NMR revealed LixZn alloy formation through an irreversible conversion reaction during discharge. MAS results revealed the dealloying of LixZn at the full charge step which left atomic zinc nanograins that do not undergo the re-oxidation of zinc atoms according to the cyclic voltammetry. An in situ formation of elemental zinc at the initial cycles facilitates uniform lithium deposition on subsequent cycles due to the reduced energy barrier for lithium nucleation on pure zinc as compared to ZnO. X-ray diffraction analysis indicated the crystalline formation of the LixZn alloy while scanning electron microscope showed the uniform morphology for the lithiated discharge products. Cyclic voltammetry and differential capacity functions initially predicted the conversion and alloying reactions.

Broadband Polarization Splitter-Rotator on Lithium Niobate-on-Insulator Platform

Polarization splitter-rotators (PSRs) are crucial components for controlling the polarization states of light in polarization-division multiplexing systems. However, current PSRs on the lithium niobate-on-insulator (LNOI) platform suffer from fabrication difficulty in high-precision shallow-etching and minimal feature size. In this letter, a large-bandwidth PSR is proposed based on LNOI strip-waveguide which only requires a single full etching step. The device is composed of an adiabatic taper, a Y-splitter, and a multi-mode interferometer. The minimal feature size is larger than 500 nm, which greatly reduces the difficulty of etching. Experimental results show that the insertion loss of such PSR is less than 1.5 dB with a polarization extinction ratio (PER) of more than 20 dB in a wide wavelength range of 1514–1640 nm for the TE0 mode. Additionally, a PER of 10 dB over 47 nm bandwidth (1502-1549 nm) for the TM0 mode is also demonstrated with our device. This LNOI-based PSR is promising in on-chip polarization-division multiplexing optical transmissions.

The greening ashore.

More than half a billion years ago a streptophyte algal lineage began terraforming the terrestrial habitat and the Earth's atmosphere. This pioneering step enabled the subsequent evolution of all complex life on land, and the past decade has uncovered that many traits, both morphological and genetic, once thought to be unique to land plants, are conserved across some streptophyte algae. They provided the common ancestor of land plants with a repertoire of genes, of which many were adapted to overcome the new biotic and abiotic challenges. Exploring these molecular adaptations in non-tracheophyte species may help us to better prepare all green life, including our crops, for the challenges precipitated by the climate change of the Anthropocene because the challenges mostly differ by the speed with which they are now being met.

A distributed gradient algorithm based on randomized block-coordinate and projection-free over networks

The computational bottleneck in distributed optimization methods, which is based on projected gradient descent, is due to the computation of a full gradient vector and projection step. This is a particular problem for large datasets. To reduce the computational complexity of existing methods, we combine the randomized block-coordinate descent and the Frank–Wolfe techniques, and then propose a distributed randomized block-coordinate projection-free algorithm over networks, where each agent randomly chooses a subset of the coordinates of its gradient vector and the projection step is eschewed in favor of a much simpler linear optimization step. Moreover, the convergence performance of the proposed algorithm is also theoretically analyzed. Specifically, we rigorously prove that the proposed algorithm can converge to optimal point at rate of {mathcal {O}}(1/t) under convexity and {mathcal {O}}(1/t^2) under strong convexity, respectively. Here, t is the number of iterations. Furthermore, the proposed algorithm can converge to a stationary point, where the “Frank-Wolfe” gap is equal to zero, at a rate {mathcal {O}}(1/sqrt{t}) under non-convexity. To evaluate the computational benefit of the proposed algorithm, we use the proposed algorithm to solve the multiclass classification problems by simulation experiments on two datasets, i.e., aloi and news20. The results shows that the proposed algorithm is faster than the existing distributed optimization algorithms due to its lower computation per iteration. Furthermore, the results also show that well-connected graphs or smaller graphs leads to faster convergence rate, which can confirm the theoretical results.

Synergetic deformation mechanism in hierarchical twinned high-entropy alloys

The mechanical properties of crystalline materials can be efficiently optimized using a hierarchical twinned structure. Conventional deformation mechanisms for coherent Σ3 boundaries generally involve three basic models: cross-slip, partial dislocation step, and full dislocation step. In this study, we report a novel deformation mechanism that allows the co-existence of twin-separation, phase transformations, grain rotation, and cracking, around a triple junction of twin boundaries in a hierarchical twinned high-entropy alloy. The deformation mechanisms in the reference high-entropy alloy (Fe-30Mn-10Co-10Cr at.%) were investigated using LAADF-STEM. The triple junction of the hierarchical twinned structure gradually deformed during in-situ strain and showed mechanisms significantly different from that observed in the purely twinned structures. These new mechanisms are referred to as “novel synergetic deformation mechanisms of hierarchical twin boundaries”. Understanding the fundamental mechanisms of the hierarchical twin boundaries under deformation could assist the design of strong and ductile bulk materials with hierarchical twinned structure.

Deep Ties: Cole and Ross, 1972–2020

Deep Ties: Cole and Ross, 1972–2020

Fusing of a Continuous Output PDR Algorithm With an Ultrasonic Positioning System

The availability of inertial navigation sensors in smartphones has facilitated the development of pedestrian dead reckoning (PDR) models on a large scale. These models often consist of a step detection algorithm combined with a heading estimation routine. Common approaches to step detection include searching for peaks/valleys in the acceleration signal, principle frequency estimation, and machine learning techniques. Since the sensors embedded in smart devices are prone to noise, the position error grows unbounded if unchecked and requires periodical corrections based on external measurements. In this work, we propose a novel step detection algorithm based on sine-wave approximation of the acceleration signal. This method detects step fractions as well as full steps, which allows for continuous and real-time updates. The step detection algorithm is combined with a heading estimation routine described in our previous work to obtain a stand-alone PDR model. To mitigate error accumulation, we fuse the proposed model with position and heading measurements provided by a commercial indoor positioning system based on ultrasound. We evaluate the performance of the PDR and fused model in an open office environment, by walking along a trajectory while carrying a smartphone in hand or in the pocket. The results demonstrate the feasibility of the sine-wave approximation approach to step detection, as well as the expected benefits of fusing PDR with the ultrasonic system.

Fiber-Chip Bi-Wavelength Multiplexing With Subwavelength Single-Etch Grating Coupler and Diplexer

We propose a silicon photonicgrating coupling scheme for dual-band multiplexing in optical fibers. By utilizing subwavelength grating effective refractive index engineering, a dual-band operating grating coupler and a wavelength-polarization diplexer are designed. Both devices are fabricated on a 220-nm silicon-on-insulator and require only one 220-nm full etch step to facilitate cost-effective production. The subwavelength grating coupler guides S-band and O-band lights from a single-mode fiber into a waveguide as transverse-electric and transverse-magnetic modes, while the subwavelength diplexer separates the two signals into two waveguides. Experimentally, our proposed scheme for coupling and multiplexing can achieve a total insertion loss of –4.26 dB at near 1490 nm and –5.86 dB at near 1310 nm.

Application of two-phase hybrid stepping motor based on three-phase inverter chopping control strategy in aircraft electric drive servo valve

With the development of multi-/all-electric technology, more and more aircraft platforms use electrically driven servo valves as the driving source to realize real-time adjustments of flow, pressure and temperature in the area network. The new generation of aircraft applies a stepper motor to drive the servo valve as the drive source, and utilizes the holding torque and open-loop control characteristics of the stepper motor when the stepper motor could not meet aircraft’s requirements of the reliability of the servo valve, the controllability of the opening and closing angle, and the environmental resistance. This paper develops a set of stepper motor drive servo valve control system. The system is mainly composed of flight tube bus, electromechanical management computer, remote actuation unit, remote interface unit and motor-driven servo valve. The stepper motor driver is integrated in the remote execution unit and is used to control the two-phase hybrid stepper motor to drive the servo valve. The topology of a three-phase inverter bridge drive is used to achieve the two-phase double four-shot drive, which saves about 25% power drive hardware. By controlling the two-phases motor, the direction and amplitude of the current one can realize micro-step control. The test and simulation result show that the system has higher control accuracy and better acceleration. The deceleration characteristics in two-phase full step and micro step working modes can expand the application of electric servo valve and improve aircraft performance.

The Effect of Adding a Training Device and Smartphone Application to Traditional Verbal Counseling in Asthmatic Children.

IntroductionNew training devices have been introduced to help in inhaler counseling by addressing the inspiratory flow through the metered-dose inhaler (MDI), which is the most important problem of the MDI inhalation technique. This study aims to compare the effects of MDI traditional verbal counseling and advanced counseling using training devices with a smartphone application in pediatric asthmatic patients.MethodsA total of 201 pediatric asthmatic subjects (8–18 years) were divided into two groups: a verbal counseling group, who received only MDI verbal counseling training (n = 101), and an advanced counseling group who received counseling using a training device (Flo-Tone with Trainhaler smartphone application) in addition to the traditional MDI verbal counseling (n = 100). Every patient in the two groups attended three counseling visits, 1 month apart. At each visit, pulmonary functions [peak expiratory flow (PEF), forced expiratory volume in 1 s (FEV1) as % of predicted] were measured. Also, patients were asked to perform their normal inhalation technique using their MDI, and mistakes were detected and recorded by the investigator. Then, patients were trained on the correct steps of the MDI inhalation technique using either verbal counseling or advanced counseling depending on their study group. In the advanced group, the Flo-Tone was connected to the mouthpiece of the MDI to blow a whistle while the patient inhaled from the MDI. That whistle was detected by the Trainhaler smartphone application and the duration of inhalation determined by the application was recorded.ResultsBoth groups showed a gradual significant decrease (p < 0.05) in the total mean number of MDI inhalation technique mistakes from the second visit of counseling, and the improvement continued in the third visit, with a lower number of mistakes in the advanced group especially in inhaling at a slow rate until the lungs are a full step. Also, the advanced counseling group showed a gradual significant increase (p < 0.05) in lung function (PEF and FEV1% of predicted) from the second visit of counseling, particularly (FEV1% predicted) results which showed a greater and more rapid overall improvement in the advanced group compared to the limited overall improvements that occurred in the control group, while significant improvement (p < 0.05) of lung function was obtained at the third visit in the verbal counseling group. In the advanced group, the number of seconds measured by the smartphone application, which represents the duration of inhalation, increased significantly (p < 0.05) in the second and third visits.ConclusionsThe addition of training devices and smartphone applications to traditional verbal counseling of MDI inhalation technique in asthmatic children resulted in significant improvements in lung function (especially in FEV1% of predicted results), and duration of inhalation, and progressive decreases in the average number of MDI inhalation techniques errors compared to the verbal counseling group.

The absorptive capacity process: an exposition and update

PurposeThis study investigates the development of absorptive capacity. Using an integrated cognitive learning perspective, this study provides empirical evidence about the conceptual absorptive capacity model through examining the full process step by step. Two groups of moderating variables were studied—namely, social integration and appropriability—to examine their impact on the process.Design/methodology/approachThis study employed a longitudinal study from a community service program (Kuliah Kerja Nyata) at Universitas Gadjah Mada, Yogyakarta, Indonesia, by using surveys at the beginning and the end of the project. Of 492 teams from 2,444 students participated in the study. Each individual within a team had at least one project assigned to him/her during the project. The absorptive capacity process was examined through six consecutive models and analysed using hierarchical linear modelling. The moderating variables were tested using the Moderated Regression Analysis and Wald tests.FindingsThe study confirms the full cycle of absorptive capacity as an independent, dynamic and complex process; it involves acquiring, assimilating, transforming and exploiting sequencing variables from the individual level to the team level and vice versa using feed-forward and feedback mechanisms adopted from the 4I framework of organisational learning. However, the roles of the moderating variables are still inconclusive due to some possible factors, which were also reflected by the U-phenomenon.Originality/valueThis study provides vital support to the learning theory as well as to the organisation learning concept. This study also reveals empirical evidence about the unsupported moderating variables behave during a project cycle, such as what they function, how they evolve and what we should do about the moderating factors during a project. The findings of this study provide practical suggestions and highlight areas for future research.

Timesync: Web Based Timetable Scheduling and Visualization System for Schools and Colleges

Timetable scheduling is a problem that concerns every teaching institution. Every semester or year a new timetable must be produced to take account of faculty, student and course changes causing a necessarily large amount of work. All institutions face a considerable number of difficulties especially before the start of academic semesters in colleges due to the increased number of students and courses. Also, visualizing the timetable needs drastic amount of work like to print them on papers and display it then to its respective classes, that too in colleges need to be secured since it got snatched away by the students there. And timetable updation require to follow full steps as followed during its creation in traditional paper-based method but here using timesync, it makes everything so smooth that it need to only update it with its user-friendly UI and no need to follow other steps as in orthodox method. The main objective of this study is to develop a web-based application for timetable scheduling and visualizing for schools and colleges. However, some work and studies still need to be done to make this system further smart and consistent as described in the recommendations section.