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A physically based material model, taking into account the interdependence of material microstructure and yield strength, is presented for an Al 5182 series aluminum alloy for the simulation of friction stir welding using continuum mechanics approaches. A microstructure evolution equation considering dislocation density and grain size is used in conjunction with a description of yield stress. In order to fit experimental stress-strain curves, obtained from compression tests at various strain rates and temperatures, phenomenological relationships are developed for some of the model parameters. The material model is implemented in smoothed particle hydrodynamic research code as well as in the commercial finite element code Abaqus. Simulations for various strain rates and temperatures were performed and compared with experimental results as well as between the two discretization methods in order to verify the material model and the implementation. Simulations provide not only an accurate approximation of stress based on temperature, strain rate, and strain but also an improved insight into the microstructural evolution of the material.

In this paper, we experimentally study and model the electron donating character of an axial diamagnetic Pd2+ion in four metalloligated lanthanide complexes of formula [PPh4][Ln{Pd(SAc)4}2] (SAc–= thioacetate, Ln = Tb, Dy, Ho, and Er). A global model encompassing inelastic neutron scattering, torque magnetometry, and dc magnetometry allows to precisely determine the energy level structure of the complexes. Solid state nuclear magnetic resonance reveals a less donating character of Pd2+compared to the previously reported isostructural Pt2+-based complexes. Consequently, all complexes invariably show a lower crystal field strength compared to their Pt2+-analogues. The dynamic properties show an enhanced single molecule magnet behavior due to the suppression of quantum tunneling, in agreement with our model.

Patients hospitalized in the intensive care unit (ICU) often have multiple support lines and devices that need routine imaging evaluation by radiologists. In patients with cardiogenic shock or depressed cardiac function, mechanical circulation support devices are used in combination with medical therapies to improve patient outcomes and sometimes can stabilize patients for surgical intervention. This article discusses some of the more commonly encountered mechanical circulation devices seen in ICU patients, including intra-aortic balloon pumps, Impella devices, extracorporeal membrane oxygenation cannulas, and ventricular assist devices. Normal appearance and commonly encountered device-related complications that can be diagnosed on imaging are reviewed.

For signal shaping problems, in contrast to reference following problems, a possibility is to make use of the signal’s shape as a control objective, described by a difference equation. In order to do this, a shape class is defined, giving a measure of how close to a specific shape a signal is. The shape class defines the weighting matrices of the standard quadratic cost function of a model predictive controller. The optimization problem is solved with constraints using a standard quadratic program solver. An application example shows the suitability of the approach for active power filters.

This work reveals the positioning of natural gas in the evolution of world energy and the general law of its development. In the long-term adjustment of energy structure, natural gas has gradually become the primary energy source because of five factors: policy, resources, technology, facilities, and market. To expedite the revolution of energy production and consumption, China must urgently expand the use of natural gas toward a more positive role in complementing coal and renewable energy and prioritize its usage in three areas, namely, urban gas, power generation, and industrial fuel. Natural gas is expected to account for approximately 15% of China’s total energy consumption in the future. For natural gas to be the primary energy, the exploitation of gas resources must be expanded, resource access must be improved, a flexible trade system must be set up, infrastructure investment must be increased, and the security system must be enhanced.

Rapid declines in legacy poly- and perfluoroalkyl substances (PFASs) have been reported in human populations globally following changes in production since 2000. However, changes in exposure sources are not well understood. Here, we report serum concentrations of 19 PFASs (?19PFAS) measured in children between 1993 and 2012 from a North Atlantic fishing community (Faroe Islands). Median ?19PFAS concentrations in children (ages 5–13 years) peaked in 2000 (47.7 ng mL–1) and declined significantly by 14.4% year–1until 2012. Principal component analysis (PCA) identified two groups of PFASs that likely reflect exposures from diverse consumer products and a third group that consisted of perfluorocarboxylic acids (PFCAs) with nine or more carbons (C = 9). These C = 9 PFASs are strongly associated with mercury in children’s hair, a well-established proxy for seafood consumption, especially perfluoroundecanoic acid (PFUnDA, r= 0.72). Toxicokinetic modeling shows PFAS exposures from seafood have become increasingly important (53% of perfluorooctanesulfonate, PFOS, in 2012), despite a decline in whale consumption in recent years. We infer that even in a major seafood-consuming population, declines in legacy PFAS exposure after 2000 were achieved by the rapid phase out of PFOS and its precursors in consumer products. These results emphasize the importance of better understanding exposures to replacement PFASs in these sources.

Intelligent driving has been prevailing worldwide and is also challenging, which can be complicated by the factors of human drivers. In this paper, a novel collision avoidance strategy is proposed to enhance driving safety in highway overtaking by comprehensively considering the driver’s steering intent. First, in order to capture the driver’s operational characteristics from the driving data, we formulate the prediction of the driver’s steering intent and the ego vehicle’s states as a multivariate time series (MTS) forecasting problem, which is then handled by deep learning with a time pattern attention mechanism (DL-Attn). Second, a predictive risk field (PRF) model is proposed to quantify the real-time overtaking risk based on the above prediction results. Then, the overtaking is evaluated via a personalized risk threshold which can be set for a specific driver via experiments. Next, a linear time-varying model predictive control (LTV-MPC) -based assistance controller is designed so as to interfere in the risky overtaking and take over the ego vehicle from the driver to avoid possible collisions. And the feasibility and stability of the closed system are ensured theoretically. Finally, experiments are carried out in three typical cases. The results demonstrate that the proposed strategy can not only effectively improve driving safety for highway overtaking, but also identify safe overtaking to avoid unnecessary interference.

The dual-winding steer-by-wire (DW-SBW) system is a novel steer-by-wire system with dual-winding permanent magnet synchronous motors, which improves steering capability and safety. However, the current imbalance in two stator windings may lead to increased current harmonic and torque ripple, resulting in steering performance degradation and safety jeopardization. Therefore, in order to improve the current balancing capability of the DW-SBW system, this paper proposes a cross-coupling active current balance control strategy. The dynamic model and the current imbalance model of the DW-SBW system are established. The mathematical relationship between the winding parameters asymmetry and current imbalance is derived, and the impact of current imbalance on current harmonic and steering performance is revealed. A radial basis function (RBF) based active current balance fast terminal sliding mode control (FTSMC) strategy for a DW-SBW system is proposed. The fast terminal sliding mode control is applied to cross-compensate the q-axis current loop control output of the two stator windings, while the RBF neural network is used to estimate the asymmetry of the resistance and inductance parameters of the two windings. The performance of the proposed FTSMC-RBF controller is validated through computer simulations and dual-winding motor experiments. The results demonstrate that the proposed FTSMC-RBF controller is more robust and provides better current balancing performance than the FTSMC in the presence of model parameter uncertainties.

The electro-hydraulic composite steering system can reduce steering energy consumption through cooperative control of electro-hydraulic mechanisms, an inevitable trend for global commercial vehicles and green logistics. However, in cooperative control, the electro-hydraulic coupling characteristics not only lead to an increase in system energy consumption but also cause fluctuations in system speed during electro-hydraulic switching. In response to the above issues, this paper proposes a long-short-time domain steering mode selection and torque optimal allocation strategy that integrates long-time domain steering mode selection and short-time domain torque allocation. In the long-term domain, with steering energy consumption as the optimization indicator, the optimal steering mode is selected through a steering mode selection model based on the CNN-LSTM network to reduce steering energy consumption. In the short time domain, the Holt Winter exponential smoothing and support vector regression methods are combined for torque prediction, and the steering energy consumption and electro-hydraulic switching smoothness indicators are comprehensively considered. The electro-hydraulic torque distribution ratio is dynamically optimized in the rolling time domain to reduce the fluctuation of hydraulic pump speed during electro-hydraulic switching. The simulation and experimental results show that the proposed method can improve the switching smoothness of the electro-hydraulic composite steering system and reduce the system’s overall energy consumption by 54.1%.

Determination of the electronic energy spectrum of a trigonal-symmetry mononuclear Yb3+single-molecule magnet (SMM) by high-resolution absorption and luminescence spectroscopies reveals that the first excited electronic doublet is placed nearly 500 cm–1above the ground one. Fitting of the paramagnetic relaxation times of this SMM to a thermally activated (Orbach) model {τ = τ0× exp[ΔOrbach/(kBT)]} affords an activation barrier, ΔOrbach, of only 38 cm–1. This result is incompatible with the spectroscopic observations. Thus, we unambiguously demonstrate, solely on the basis of experimental data, that Orbach relaxation cannot a prioribe considered as the main mechanism determining the spin dynamics of SMMs. This study highlights the fact that the general synthetic approach of optimizing SMM behavior by maximization of the anisotropy barrier, intimately linked to the ligand field, as the sole parameter to be tuned, is insufficient because of the complete neglect of the interaction of the magnetic moment of the molecule with its environment. The Orbach mechanism is expected dominant only in the cases in which the energy of the excited ligand field state is below the Debye temperature, which is typically low for molecular crystals and, thus, prevents the use of the anisotropy barrier as a design criterion for the realization of high-temperature SMMs. Therefore, consideration of additional design criteria that address the presence of alternative relaxation processes beyond the traditional double-well picture is required.

ABSTRACTIodine is essential for human health, and dietary iodine sources are critical. Living isolated on islands in the North Atlantic Ocean fostered unique dietary traditions in the Faroe Islands. The dietary peculiarities led us to collect and measure the iodine content of local foods and beverages and calculate daily iodine intakes based on four Faroese dietary scenarios. Marine foods and birds had iodine contents from 300 µg/kg and up, markedly higher than dairy, grains, terrestrial, vegetables, and liquid foods (p<0.001). Vegetables and beverages contained negligible iodine. Wind-dried fermented lamb meat iodine content varied by 100% depending on whether it was herded on an island with beaches (105 µg/kg) or with cliffs (53 µg/kg) facing the ocean. The daily iodine intake varied from around 50 µg to just over 200 µg with diets rich in fish and whales. In conclusion, the traditional diet has been a critical source of iodine on the Faroe Islands. The Faroese may be iodine replete with traditional diets but face the risk of iodine deficiency with dietary transition towards a more western diet. Locally produced Faroese foods are therefore relevant to promote health, and may additionally support food security, local involvement and knowledge, and long-term sustainability.