Angular momentum, kinetics, and energetics, including total mechanical energy and its rate of change in relation to power exchange, are important quantities when analyzing human motion in sports, physical labor, and rehabilitation. Inertial measurement units (IMU)-based motion capture (MOCAP) systems provide a portable solution for the ambulatory analysis of these quantities which optical MOCAP systems do not offer. Yet, evaluating IMU-based estimates of these quantities by referencing optical systems is limited by the fact that these systems only measure positions, not kinetic and energetic quantities. To evaluate the accuracy of an IMU-based method for estimating kinetic and energetic quantities without using any external reference, firstly, we propose an estimation method only using angular velocity and acceleration signals supplied by an IMU, and apply this to a single rigid body with known mass and inertia. Then, we propose a novel experimental validation method against physical conservation and action/reaction laws that apply during ballistic movements, using a suitably designed and reconfigurable rigid body with a structure of three orthogonal dumb-bells. The results demonstrated that we could estimate the angular momentum, kinetics, and energetics of a rigid body by only using angular velocity and acceleration signals of an IMU, and the estimation accuracy was well evaluated by the proposed validation method. However, the results showed that the errors in original IMU measurements under dynamic conditions especially concerning angular velocity, uncertainties in calculating rigid body parameters, and vibration propagation due to limited rigidity of tubes of the rigid body influenced the estimation accuracy.

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Multiplicative watermarking (MWM) is an active diagnosis technique for the detection of highly sophisticated attacks, but is vulnerable to malicious agents that use eaves-dropped data to identify and then remove or replicate the watermark. In this work, we propose a scheme to protect the parameters of MWM, by proposing a design strategy based on piecewise affine (PWA) hybrid dynamical systems, called hybrid multiplicative watermarking (HMWM). Due to the design decision to make certain states of the HMWM systems unobservable, we show that parameter reconstruction by an eavesdropper is infeasible, from both a computational and a system-theoretic perspective, while not altering the system's closed-loop performance.

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Implementation of many quantum information protocols requires an efficient initialization of the quantum register. In the present paper, we optimize a population trapping protocol for initializing a hybrid spin register associated with a single nitrogen-vacancy (NV) center in diamond. We initialize the quantum register by polarizing the electronic and nuclear spins of the NV with a sequence of microwave, radio-frequency, and optical pulses. We use a rate equation model to explain the distribution of population under the effect of the optical pulses. The model is compared to the experimental data obtained by performing partial quantum state tomography. To further increase the spin polarization, we propose a recursive protocol with optimized optical pulses. We also discuss the role of the relative values of the nuclear- and electronic-spin pumping rate in achieving the maximum degree of spin polarization. @en

In mega projects, the stakeholders may be exposed to significant on-site construction risk, especially the owners and insurance companies who take the most responsibility for the risk loss. It is difficult for insurance companies to diversify their risks by undertaking enough similar policies, and participating in on-site risk management has become an important method of active risk control. Based on the principal-agent relationship between the owner, insurance company, and contractor, this paper establishes incentive mechanisms for risk management considering the common agency and exclusive agency models. The results show that an insurance company's involvement in the common agency model creates external effects that can improve the utility of both the owner and the insurance company. The owner is then willing to provide a higher incentive coefficient, and the contractor's nonrisk and risk management efforts increase accordingly. From the owner's perspective, the influence of the participants' characteristics and external uncertainties on the incentive strategy are discussed. The results recommend that it is better for the owners and insurance companies to jointly establish a good cooperative relationship and build the incentive mechanism. The spillover effect has a positive effect on the cooperation between the two parties, while the impact of the uncertainty in risk management output on the cooperative relationship is negative. This paper contributes to the body of knowledge for understanding the on-site risk management considering stakeholders' participation and provides a practical mode for owners and insurance companies to implement active risk management in mega projects, thus achieving better risk governance of mega projects.

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Magnon spintronics is a prosperous field that promises beyond-CMOS technology based on elementary excitations of the magnetic order that act as information carriers for future computational architectures. Unidirectional propagation of spin waves is key to the realization of magnonic logic devices. However, previous efforts to enhance the magnetostatic surface spin wave nonreciprocity did not realize (let alone control) purely unidirectional propagation. Here we experimentally demonstrate excitation of unidirectional exchange spin waves by a nanoscale magnetic grating consisting of Co nanowires fabricated on an ultrathin yttrium iron garnet film. We explain and model the nearly perfect unidirectional excitation by the chirality of the magneto-dipolar interactions between the Kittel mode of the nanowires and the exchange spin waves of the film. Reversal of the magnetic configurations of film and nanowire array from parallel to antiparallel changes the direction of the excited spin waves. Our results raise the prospect of a chiral magnonic logic without the need to involve fragile surface states.

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Wind energy has experienced a continuous cost reduction in the last decades. A popular cost reduction technique is to increase the rated power of the wind turbine by making it larger. However, it is not clear whether further upscaling of the existing wind turbines beyond the 5–7MW range is technically feasible and economically attractive. To address this question, this study uses 5, 10, and 20MW wind turbines that are developed using multidisciplinary design optimization as upscaling data points. These wind turbines are upwind, 3-bladed, pitch-regulated, variable-speed machines with a tubular tower. Based on the design data and properties of these wind turbines, scaling trends such as loading, mass, and cost are developed. These trends are used to study the technical and economical aspects of upscaling and its impact on the design and cost. The results of this research show the technical feasibility of the existing wind turbines up to 20 MW, but the design of such an upscaled machine is cost prohibitive. Mass increase of the rotor is identified as a main design challenge to overcome. The results of this research support the development of alternative lightweight materials and design concepts such as a two-bladed downwind design for upscaling to remain a cost effective solution for future wind turbines. @en

To investigate the groundwater levels changes effects on the transpiration of Salix psammophila (S. psammophila) bush, systemic measurements of meteorological conditions, sap flow of S. psammophila, soil water contents and groundwater levels were conducted in the Hailiutu River catchment, NW of China. Based on the collected field data, Hydrus-1D software package was used to calibrate water movement for root uptake in the saturated– unsaturated zone. The soil hydraulic parameters and root uptake function parameters were calibrated. The simulated results of soil water contents and sap flow fitted well with the observed ones. Based on the calibrated hydraulic parameters, different groundwater levels were imposed at the low boundary to simulate the groundwater levels changes effects on the transpiration. The relationship between ratio of actual transpiration and potential (T/Tp) and groundwater water table depth was established. The results shows that the ratio of actual transpiration and potential transpiration decreases with groundwater table depth increase as inverse ‘S’ shape. And the turn point is corresponding to the extinct depth, i.e., no groundwater contribution to S. psammophila transpiration. To further verify this phenomenon is universal, the soil hydraulic parameters were replaced with the other five groups in the calibrated forward model. The results confirmed the similar changes of Ta/Tp with the groundwater levels changed, i.e. inverse ‘S’ shape. However, the extinction depth is different corresponding to different soil hydraulic parameters. So, the research results indicated the relationship between transpiration and groundwater levels is non-linear function @en

The cometabolism as a technique for enhancing biodegradation of pentachlorophenol (PCP) has been widely used, but the effect of dosing mode of growth substrates on the cometabolic degradation of PCP in an anaerobic system with and without the addition of ZVI is still not clear. In this study, the effects of dosing modes of sodium acetate as co-substrate, i.e., one-step pulse, evenly distributed pulse, and stepwise declining pulse, and zero-valent iron (ZVI) of 1 mg l−1 on pentachlorophenol (PCP) degradation and changes in anaerobic microbial community were examined in batch tests. The results indicated that the degradation kinetic constants of PCP were related to the dosing mode of co-substrate. The complete mineralization rates of PCP in the two groups with evenly distributed pulse mode and stepwise declining pulse mode were faster than the observed rates of the group with one-step pulse mode, according to the quantitative analysis of 2,3,5,6-tetrachlorophenol, 2,3,5-tetrachlorophenol, and 2,5-chlorophenol. In addition, there was a substantial change in the content of intracellular polysaccharide in the cometabolic process of the one-step pulse and stepwise declining pulse groups. Furthermore, the electron transport system (ETS) activities reached to the maximum values of 0.841 and 0.813 ug g−1 in these two groups with the addition of 1 g l−1 ZVI, respectively. Moreover, Alcaligenes (11.02%), Comamonas (14.58%), and Ralstonia (9.16%) were the dominant genera in the groups with the three co-substrate dosing modes, respectively. This study provides a new insight into achieving anaerobic cometabolic degradation of PCP with different dosing modes of co-substrate.@en