Full Joint Research Articles

Measurement of Decay Time Constant of Shielding Current in ITER-TF Joint Samples

Joint sample tests have been carried out as a qualification test for ITER Toroidal Field (TF) coils. The joint sample comprises two short TF conductors that have “twin-box” joint terminals at both ends. The lower joint is a testing part that is a full size joint of the TF coils. Hall probes are attached on the lower joint box at around the center of the external field coil of the test facility. The magnetic field induced by shielding currents in the joint can be estimated from the difference between the measured magnetic field strength and the magnetic field generated by the external field coil. The magnetic field by the shielding currents during shut-off of the external field coil from -1.0 T is evaluated for six samples. The decay time constants of the shielding currents are gradually elongated with decrease of the shielding currents in all the samples. In comparison with simulation results, it is considered that the main shielding current flows in superconducting cables in the two conductors with crossing the jointed plane and that the joint resistance is decreased at low total current.

The fracture mechanism of Cu3Sn-microporous copper composite joint by thermal compression bonding process

The bonding performances of the composite joint that made of microporous copper and Sn were investigated in this paper. It could rapidly generate .The Cu3Sn- microporous copper composite joint with a thickness of 100 μm was successfully obtained after bonding at 360 °C for 5 min under a low pressure of 0.6 MPa.The shear strength of the composite joint reached 166.05 MPa, which was 2.5 times higher than that of full Cu3Sn joint. The fracture mechanism of composite joint was analyzed by fracture morphology.A large amount of copper could be observed in the fractured surface of composite joint.The self-locking structure was generated between the Cu3Sn and microporous copper in the composite joint.The microporous copper provided more nucleation particles during the formation of Cu3Sn and finally resulted in the refinement of the Cu3Sn grains. In addition,the occurrence of fracture was delayed due to the plastic deformation of microporous copper.

What’s New in Hand and Wrist Surgery

What’s New in Hand and Wrist Surgery

Strengthening of deficient RC jointswith diagonally placed external C-FRP ropes

Deficient beam-column joints of reinforced concrete (RC) structures designed to older practices and codes often lead to destructive local or global failures. A strengthening technique for these joints based on the use of the new and innovative Carbon-FRP (C-FRP) ropes is presented and investigated. The C-FRP ropes are diagonally placed in superficial notches on the two sides of the joint. Two full scale external substandard joint subassemblages with the same characteristics, one unstrengthened and one strengthened with diagonally applied C-FRP ropes, are constructed and tested in cyclic loading. Special attention has been given to the elaboration of the acquired test measurements. The extracted conclusions are based on the comparative study of the hysteretic responses of the specimens, the observed maximum load envelopes, the comparisons of the joint body shear deformations as measured using diagonally mounted LVTDs, the calculated nominal principal stresses developed in the joint regions, the assessed joint damage as expressed by the damage index by Park and Ang and finally the calculated values of the equivalent damping ratio. From these comparisons it is concluded that application of diagonally mounted C-FRP ropes on the two sides of the joint body of exterior connections is an efficient easy-to-apply technique for the strengthening of substandard RC joints.

Bayesian comparison of interacting modified holographic Ricci dark energy scenarios

We perform a Bayesian model selection analysis for interacting scenarios of dark matter and modified holographic Ricci dark energy (MHRDE) with linear interacting terms. We use a combination of some of the latest cosmological data such as type Ia supernovae, cosmic chronometers, the local value of the Hubble constant, baryon acoustic oscillations measurements and cosmic microwave background through the angular scale of the sound horizon at last scattering. We find moderate/strong evidence against all the MHRDE interacting scenarios studied with respect to Lambda CDM when the full joint analysis is considered.

Matter trispectrum: theoretical modelling and comparison to N-body simulations

The power spectrum has long been the workhorse summary statistics for large-scale structure cosmological analyses. However, gravitational non-linear evolution moves precious cosmological information from the two-point statistics (such as the power spectrum) to higher-order correlations. Moreover, information about the primordial non-Gaussian signal lies also in higher-order correlations. Without tapping into these, that information remains hidden. While the three-point function (or the bispectrum), even if not extensively, has been studied and applied to data, there has been only limited discussion about the four point/trispectrum. This is because the high-dimensionality of the statistics (in real space a skew-quadrilateral has 6 degrees of freedom), and the high number of skew-quadrilaterals, make the trispectrum numerically and algorithmically very challenging. Here we address this challenge by studying the i-trispectrum, an integrated trispectrum that only depends on four k-modes moduli. We model and measure the matter i-trispectrum from a set of 5000 QUIJOTE N-body simulations both in real and redshift space, finding good agreement between simulations outputs and model up to mildly non-linear scales. Using the power spectrum, bispectrum and i-trispectrum joint data-vector covariance matrix estimated from the simulations, we begin to quantify the added-value provided by the i-trispectrum. In particular, we forecast the i-trispectrum improvements on constraints on the local primordial non-Gaussianity amplitude parameters fnl and gnl. For example, using the full joint data-vector, we forecast fnl constraints up to two times (∼32%) smaller in real (redshift) space than those obtained without i-trispectrum.

Time course of risk factors associated with mortality of 1260 critically ill patients with COVID-19 admitted to 24 Italian intensive care units

PurposeTo evaluate the daily values and trends over time of relevant clinical, ventilatory and laboratory parameters during the intensive care unit (ICU) stay and their association with outcome in critically ill patients with coronavirus disease 19 (COVID-19).MethodsIn this retrospective–prospective multicentric study, we enrolled COVID-19 patients admitted to Italian ICUs from February 22 to May 31, 2020. Clinical data were daily recorded. The time course of 18 clinical parameters was evaluated by a polynomial maximum likelihood multilevel linear regression model, while a full joint modeling was fit to study the association with ICU outcome.Results1260 consecutive critically ill patients with COVID-19 admitted in 24 ICUs were enrolled. 78% were male with a median age of 63 [55–69] years. At ICU admission, the median ratio of arterial oxygen partial pressure to fractional inspired oxygen (PaO2/FiO2) was 122 [89–175] mmHg. 79% of patients underwent invasive mechanical ventilation. The overall mortality was 34%. Both the daily values and trends of respiratory system compliance, PaO2/FiO2, driving pressure, arterial carbon dioxide partial pressure, creatinine, C-reactive protein, ferritin, neutrophil, neutrophil–lymphocyte ratio, and platelets were associated with survival, while for lactate, pH, bilirubin, lymphocyte, and urea only the daily values were associated with survival. The trends of PaO2/FiO2, respiratory system compliance, driving pressure, creatinine, ferritin, and C-reactive protein showed a higher association with survival compared to the daily values.ConclusionDaily values or trends over time of parameters associated with acute organ dysfunction, acid–base derangement, coagulation impairment, or systemic inflammation were associated with patient survival.

A full matrix joint optimization method for hardware implementation of AES MixColumns/InvMixColumns

A full matrix joint optimization method for hardware implementation of AES MixColumns/InvMixColumns

СОЦІАЛЬНА ВІДПОВІДАЛЬНІСТЬ ЯК СКЛАДОВА ІННОВАЦІЙНОГО ОСВІТНЬОГО ПРОЦЕСУ ТА ЗАБЕЗПЕЧЕННЯ КОНКУРЕНТОСПРОМОЖНОСТІ ЗАКЛАДУ ВИЩОЇ ОСВІТИ

UDC 338.242; JEL Classification: М14 The purpose is to substantiate the model of innovative educational process of practice-oriented training as a socially oriented person with a high level of not only mandatory professional competencies (educational and research component), but also innovation-oriented with entrepreneurial skills. Methodology of research. The theoretical and methodological basis is the work of leading domestic and foreign economists, which are considered social responsibility in the context of ensuring the competitiveness of higher education institutions through partnerships "education-society-business". Methods of generalization and abstraction are used; method of analysis and synthesis. Findings. Dynamic market relations require the modern educational system to implement a model of innovative educational process of practice-oriented professional training with the transfer of the vector "teacher - discipline" to "student-professional competencies". That is, the technology and training program should be systematically modernized, both in terms of content and aspects of quality assurance, provided that the implementation of a set of certain pedagogical conditions. The effective functioning of this system and professional training should be ensured by the implementation of a set of pedagogical conditions that meet the demands of social production, business and the expected social consequences. The model of innovative educational process should use the unity of interacting elements (subsystems): objective, normative, organizational and effective, which would contribute to the comprehensive formation of modern market thinking of the future specialist and his awareness of social responsibility. Originality. The paper theoretically substantiates the feasibility of using the model of innovative educational process of professional practice-oriented training, which should be a holistic multilevel structural and functional pedagogical system, combine elements of general and professional education, as well as provide education for socially oriented professionals. In this model, social responsibility is a kind of innovative vector for the development of higher education, contributes to the acquisition of a high level of not only traditional professional competencies, but also the personal qualities of the future specialist. Practical value. The practical implementation of practice-oriented professional training is associated with the development of a new concept in educational activities, new content and innovative forms of pedagogical work on the basis of social responsibility. In this case, the higher education institution bears full joint several social responsibility for the result of training and education of a socially oriented individual, which ensures the acquisition of competitive advantages for the future.

Brazilian Jiu-Jitsu fighters present greatest rapid and maximal strength imbalances at extreme elbow angles

BackgroundThe performance of Brazilian jiu-jitsu (BJJ) fighters is dependent on rapid and maximal elbow strength actions. Appropriate strength balance between elbow flexors (F) and extensors (E) across the full joint range of motion may be required to decrease risk of injuries. AimTo compare rapid and maximal elbow F/E strength balance through full range of motion in BJJ fighters. Materials and methodsTwenty-three male BJJ fighters (27.9 ± 4.6 years, 82.9 ± 10.9 kg, 174.5 ± 6.8 cm, and 15.3 ± 6.8% body fat) with 8.2 ± 6.5 years of practice volunteered to participate. Participants were tested for rate of torque development (RTD) and peak torque (PT) of elbow F and E at six angles (45°, 60°, 75°, 90°, 105°, and 120°; 0° = full extension). Rapid (F RTD/E RTD) and maximal (F PT/E PT) angle-specific torque (AST) ratios were calculated. ResultsRapid AST ratio at 45° (0.66 ± 0.18) and maximal AST ratio at 45° (0.91 ± 0.16) and 120° (0.88 ± 0.20) were significantly less than all other AST ratios at mid-point angles of elbow range of motion (p < 0.05). Individual data demonstrates that both beginners and advanced BJJ fighters present overall similar rapid and maximal F/E AST imbalances. ConclusionBJJ fighters present greater rapid and maximal strength imbalances at extreme-compared to mid-point angles of range of motion. Results may benefit coaches to develop strength exercises focusing on these specific angles to potentially reduce the risk of elbow injury and improve performance of BJJ fighters.

Investigating the effect of chemistry on the flash butt weldability of steels through a combination of experiments and modeling

Flash butt weld process parameters determine the weld quality. The presence of weld defects due to inappropriate process parameters leads to entrapment of oxides in the weld causes premature failure. It was also observed that the flash butt process parameter is dependent on the chemistry of the steel that is processed. The high weight percentage of Mn and Si leads to a higher weight fraction of the oxides during welding. Altering the flashing length and upset length leads to the elimination of weld defects achieving full joint strength. Thermodynamic calculations predict the oxides to be primarily FeO, Fe2O3 (hematite), and SiO2 (cristobalite) along with the presence of MnO, Mn2O3, and Cr2O3. The presence of Mn, Al, and Ti in the oxides at the fractured surface is correlated with the chemical potential of these elements in the liquid steel. It can be inferred from the modeling and experimental results that with an increase in temperature, a more liquid slag phase is formed as compared to solid oxides. Slag is less viscous and can be easily extruded during the upsetting stage as opposed to solid inclusion which can be trapped during the welding operation.

Risk of crop failure due to compound dry and hot extremes estimated with nested copulas

Abstract. The interaction between co-occurring drought and hot conditions is often particularly damaging to crop's health and may cause crop failure. Climate change exacerbates such risks due to an increase in the intensity and frequency of dry and hot events in many land regions. Hence, here we model the trivariate dependence between spring maximum temperature and spring precipitation and wheat and barley yields over two province regions in Spain with nested copulas. Based on the full trivariate joint distribution, we (i) estimate the impact of compound hot and dry conditions on wheat and barley loss and (ii) estimate the additional impact due to compound hazards compared to individual hazards. We find that crop loss increases when drought or heat stress is aggravated to form compound dry and hot conditions and that an increase in the severity of compound conditions leads to larger damage. For instance, compared to moderate drought only, moderate compound dry and hot conditions increase the likelihood of crop loss by 8 % to 11 %, while when starting with moderate heat, the increase is between 19 % to 29 % (depending on the cereal and region). These findings suggest that the likelihood of crop loss is driven primarily by drought stress rather than by heat stress, suggesting that drought plays the dominant role in the compound event; that is, drought stress is not required to be as extreme as heat stress to cause similar damage. Furthermore, when compound dry and hot conditions aggravate stress from moderate to severe or extreme levels, crop loss probabilities increase 5 % to 6 % and 6 % to 8 %, respectively (depending on the cereal and region). Our results highlight the additional value of a trivariate approach for estimating the compounding effects of dry and hot extremes on crop failure risk. Therefore, this approach can effectively contribute to design management options and guide the decision-making process in agricultural practices.

Effect of laser welding on the mechanical and degradation behaviour of Fe-20Mn-0.6C bioabsorbable alloy

The present work aims at exploring the influence of laser welding on the functional behaviour of a Fe-20Mn-0.6C (wt.%) bioabsorbable alloy. At first, the selection of the most suitable process speed (40 mm/s) was done in order to obtain a full penetration joint with limited taper. Then, microstructural and mechanical analyses of welded sheets confirmed suitable performance of the joint, without porosity, thus preserving chemical composition, mechanical resistance and ductility even after welding. In particular, the base material comprised both γ austenite and ε martensite, while the welded samples showed a further type of martensite, namely α’. Moreover, ultimate tensile strength (1095 MPa and 1104 MPa in base and welded material, respectively) and elongation to failure (61.3% and 60.9%, respectively) were almost not influenced by the welding process. Considering the absorbable nature of these alloys, static immersion degradation tests were carried out, and confirmed that the surface of the welded bead did not exhibit a significant variation of the material degradation rate after 14 days in modified Hanks’ solution. Finally, a significant accumulation of degradation products, mainly (Fe,Mn)CO3, was observed along the joining line.

Bayesian Dynamic Mapping of an Exo-Earth from Photometric Variability

Abstract Photometric variability of a directly imaged exo-Earth conveys spatial information on its surface and can be used to retrieve a two-dimensional geography and axial tilt of the planet (spin–orbit tomography). In this study, we relax the assumption of the static geography and present a computationally tractable framework for dynamic spin–orbit tomography applicable to time-varying geography. First, a Bayesian framework of static spin–orbit tomography is revisited using analytic expressions of the Bayesian inverse problem with a Gaussian prior. We then extend this analytic framework to a time-varying one through a Gaussian process in the time domain, and present analytic expressions that enable efficient sampling from a full joint posterior distribution of geography, axial tilt, spin rotation period, and hyperparameters in the Gaussian process priors. Consequently, it only takes 0.3 s for a laptop computer to sample one posterior dynamic map conditioned on the other parameters with 3072 pixels and 1024 time grids, for a total of ∼3 × 106 parameters. We applied our dynamic mapping method to a toy model and found that the time-varying geography was accurately retrieved along with the axial tilt and spin rotation period. In addition, we demonstrated the use of dynamic spin–orbit tomography with a real multicolor light curve of the Earth as observed by the Deep Space Climate Observatory. We found that the resultant snapshots from the dominant component of a principal component analysis roughly captured the large-scale, seasonal variations of the clear-sky and cloudy areas on the Earth.

PUT-Hand—Hybrid Industrial and Biomimetic Gripper for Elastic Object Manipulation

In this article, the design of a five-fingered anthropomorphic gripper is presented specifically designed for the manipulation of elastic objects. The manipulator features a hybrid design, being equipped with three fully actuated fingers for precise manipulation, and two underactuated, tendon-driven digits for secure power grasping. For ease of reproducibility, the design uses as many off-the-shelf and 3D-printed components as possible. The on-board controller circuit and firmware are also presented. The design includes resistive position and angle sensors in each joint, resulting in full joint observability. The controller has a position-based controller integrated, along with USB communication protocol, enabling gripper state reporting and direct motor control from a PC. A high-level driver operating as a Robot Operating System node is also provided. All drives and circuitry of the PUT-Hand are integrated within the hand itself. The sensory system of the hand includes tri-axial optical force sensors placed on fully actuated fingers’ fingertips for reaction force measurement. A set of experiments is provided to present the motion and perception capabilities of the gripper. All design files and source codes are available online under CC BY-NC 4.0 and MIT licenses.

Multivariate Hawkes process for cyber insurance

AbstractIn this paper, we propose a multivariate Hawkes framework for modelling and predicting cyber attacks frequency. The inference is based on a public data set containing features of data breaches targeting the US industry. As a main output of this paper, we demonstrate the ability of Hawkes models to capture self-excitation and interactions of data breaches depending on their type and targets. In this setting, we detail prediction results providing the full joint distribution of future cyber attacks times of occurrence. In addition, we show that a non-instantaneous excitation in the multivariate Hawkes model, which is not the classical framework of the exponential kernel, better fits with our data. In an insurance framework, this study allows to determine quantiles for number of attacks, useful for an internal model, as well as the frequency component for a data breach guarantee.

Measurements of H0 in modified gravity theories: The role of lensed quasars in the late-time Universe

In this work, we obtain measurements of the Hubble constant in the context of modified gravity theories. We set up our theoretical framework by considering viable cosmological $f(R)$ and $f(T)$ models, and we analyzed them through the use of geometrical data sets obtained in a model-independent way, namely, gravitationally lensed quasars with measured time delays, standard clocks from cosmic chronometers, and standard candles from the Pantheon Supernovae Ia sample. We find $H_0=(72.4\pm 1.4)$ km s$^{-1}$ Mpc$^{-1}$ and $H_0=(71.5\pm 1.3)$ km s$^{-1}$ Mpc$^{-1}$ for the $f(R)$ and $f(T)$ models, respectively. Our results represent 1.9\% and 1.8\% measurements of the Hubble constant, which are fully consistent with the local estimate of $H_0$ by the Hubble Space Telescope. We do not find significant departures from general relativity, as our study shows that the characteristic parameters of the extensions of gravity beyond general relativity are compatible with the $\Lambda$CDM cosmology. Moreover, within the standard cosmological framework, our full joint analysis suggests that it is possible to measure the dark energy equation of state parameter at 1.2\% accuracy, although we find no statistical evidence for deviations from the cosmological constant case.

Pseudo-dynamic testing of a full-scale two-storey steel building with RBS connections

The paramount role of beam-to-column joints on the seismic response of MRFs is universally recognised and many studies have been devoted to the improvement of their ductility and energy dissipation capacity, mostly after the seismic events of Northridge and Kobe. Nevertheless, while much experimental work has been already carried out on the seismic behaviour of beam-to-column sub-assemblages, the available experimental results on full-scale structures are still quite limited.Aiming to provide a contribution to fill this knowledge gap, an experimental program has been planned at the STRENGTH Laboratory of the University of Salerno concerning the pseudo-dynamic testing of a full-scale two-storey steel building equipped with five different connection typologies.In this paper, the results of the first series of tests, dealing with MRFs with RBS connections, are presented. The mock-up has been subjected to a sequence of seven accelerograms and the results have shown that, if properly designed, RBS connections provide large energy dissipation capacity and plastic rotation supply. Nevertheless, the failure of welds due to damage accumulation can be still possible, even adopting full penetration butt joint welding details conforming to Eurocode 3 and Eurocode 8 provisions.The test results are complemented with a numerical model developed with the software SeismoStruct. The comparisons between the numerical simulations and the experimental results show that the applied mixed distributed and concentrated plasticity approach, based on the adoption of phenomenological spring models, can capture accurately the global response of the structure, but it predicts with lower accuracy the local response parameters.

Bayesian modelling of Thomson scattering and multichannel interferometer diagnostics using Gaussian processes

Electron temperature and density profiles consistent with JET high resolution Thomson scattering (HRTS) and far infrared (FIR) interferometer data are inferred by a Bayesian joint model using Gaussian processes. Forward models predicting diagnostic data including instrument effects such as optics and electronics are developed independently for both diagnostic systems in the Minerva framework, and combined as one joint model. The full joint posterior distribution of the electron temperature and density profiles, the hyperparameters of the Gaussian processes and calibration factor is explored by Markov chain Monte Carlo (MCMC) sampling. The posterior distribution of the electron density (temperature) profile is obtained by marginalising all the possible combinations of the electron temperature (density) profile, the hyperparameters and calibration factor. Therefore, the method removes profile dependency on the hyperparameters completely in addition to eliminating often-used avoidable constraints such as monotonicity and parametrisation on the profiles. The posterior distribution of the calibration factor is also calculated explaining both the HRTS and the FIR interferometer data simultaneously. Thus, absolute electron density can be obtained from the HRTS without additional experiments measuring the calibration factor.

Quantifying dosage of physical therapy using lower body kinematics: a longitudinal pilot study on early post-stroke individuals

BackgroundWhile therapy is an important part of the recovery process, there is a lack of quantitative data detailing the “dosage” of therapy received due to the limitations on in/outpatient accessibility and mobility. Advances in wearable sensor technology have allowed us to obtain an unprecedented glimpse into joint-level kinematics in an unobtrusive manner. The objective of this observational longitudinal pilot study was to evaluate the relations between lower body joint kinematics during therapy and functional gait recovery over the first three months after stroke.MethodsSix individuals with subacute stroke (< 1 month) were monitored for a total of 59 one-hour physical therapy sessions including gait and non-gait activities. Participants donned a heart rate monitor and an inertial motion capture system to measure full lower body joint kinematics during each therapy session. Linear mixed regression models were used to examine relations between functional gait recovery (speed) and activity features including total joint displacements, defined as amount of motion (AoM), step number, change in heart rate (∆HR), and types of tasks performed.ResultsAll activity features including AoM, step number, types of tasks performed (all p < 0.01), and ∆HR (p < 0.05) showed strong associations with gait speed. However, AoM (R2 = 32.1%) revealed the greatest explained variance followed by step number (R2 = 14.1%), types of tasks performed (R2 = 8.0%) and ∆HR (R2 = 5.8%). These relations included both gait and non-gait tasks. Contrary to our expectations, we did not observe a greater relation of functional recovery to motion in the impaired limb (R2 = 27.8%) compared to the unimpaired limb (R2 = 32.9%).ConclusionsThis proof-of-concept study shows that recording joint kinematics during gait therapy longitudinally after stroke is feasible and yields important information for the recovery process. These initial results suggest that compared to step number, more holistic outcome measures such as joint motions may be more informative and help elucidate the dosage of therapy.