An analysis of shock isolation characteristics of a head of a woodpecker and its application to a bionic helmet

The effect of a woodpecker’s head structure on shock isolation was investigated from a dynamic point of view. A simplified multi-degree-of-freedom model was set up to study shock isolation characteristics of a woodpecker’s head. The shock-isolation performance of this model was calculated and analyzed by changing the dynamic parameters. And it was evaluated by two indexes: the absolute acceleration of the skull bone and the relative displacement between the skull bone and the beak. A bionic helmet model subjoining the elastic damping layer and the cushion pad was presented. Calculating the three-dimensional shock response surfaces validated it

The spectral response of Stokes’s integral to modification and truncation

In this paper, we study the spectral response of Stokes’s integral, which is determined by its modification and truncation. Two spectrally modified Stokes’s kernel functions are selected and compared to the unmodified Stokes’s kernel in terms of the spectral transfer coefficient effectiveness. Stokes’s integral is truncated at four spherical cap sizes with spherical radii ψ0 = 1◦,3◦,6◦,9◦. The results suggest that the unmodified Stokes’s integral is spectrally unstable when being arbitrarily truncated, and a modification to Stokes‘s kernel is required for a smooth geoid model

Evaluation of the GRACE-Based Global Gravity Models in Canada

Abstract. Four GRACE-based gravity models, especially EGM08, have been evaluated using the surface gravity observations, GPS-levelling, deflections of the vertical, and the recent Canadian gravimetric geoid CGG05. The RMS of the differences between the EGM08-predicted gravity anomalies and the observed anomalies is smaller than 5 mGal on sea and lake surfaces, in contrast to about 14 mGal on land in Canada. The RMS increases with increasing elevation on land, exhibiting an evident height-dependent trend, while the RMS decreases with increasing depth on sea and lake surfaces, without a significant trend. The GPS-levelling comparisons suggest that EGM08 models the geoid with an accuracy of 10 cm or better in Canada. It is comparable with the Canadian Gravimetric Geoid 2005 (CGG05). Recent releases of GRACE models show noteworthy improvement over earlier ones. The comparisons between the EGM08-predicted and astronomical deflections of the vertical show the RMS of 1.8 arc-seconds in the north-south direction, and 2.1 arc-seconds in the east-west direction, which are significantly larger than the RMS of differences between the CGG05-predicted and astronomical deflections

DKWS: A Distributed System for Keyword Search on Massive Graphs (Complete Version)

Due to the unstructuredness and the lack of schemas of graphs, such as knowledge graphs, social networks, and RDF graphs, keyword search for querying such graphs has been proposed. As graphs have become voluminous, large-scale distributed processing has attracted much interest from the database research community. While there have been several distributed systems, distributed querying techniques for keyword search are still limited. This paper proposes a novel distributed keyword search system called \DKWS. First, we \revise{present} a {\em monotonic} property with keyword search algorithms that guarantees correct parallelization. Second, we present a keyword search algorithm as monotonic backward and forward search phases. Moreover, we propose new tight bounds for pruning nodes being searched. Third, we propose a {\em notify-push} paradigm and \PINE {\em programming model} of \DKWS. The notify-push paradigm allows {\em asynchronously} exchanging the upper bounds of matches across the workers and the coordinator in \DKWS. The \PINE programming model naturally fits keyword search algorithms, as they have distinguished phases, to allow {\em preemptive} searches to mitigate staleness in a distributed system. Finally, we investigate the performance and effectiveness of \DKWS through experiments using real-world datasets. We find that \DKWS is up to two orders of magnitude faster than related techniques, and its communication costs are $7.6$ times smaller than those of other techniques

Metal oxide semiconductor nanomembrane-based soft unnoticeable multifunctional electronics for wearable human-machine interfaces

Wearable human-machine interfaces (HMIs) are an important class of devices that enable human and machine interaction and teaming. Recent advances in electronics, materials, and mechanical designs have offered avenues toward wearable HMI devices. However, existing wearable HMI devices are uncomfortable to use and restrict the human body's motion, show slow response times, or are challenging to realize with multiple functions. Here, we report sol-gel-on-polymer-processed indium zinc oxide semiconductor nanomembrane-based ultrathin stretchable electronics with advantages of multifunctionality, simple manufacturing, imperceptible wearing, and robust interfacing. Multifunctional wearable HMI devices range from resistive random-access memory for data storage to field-effect transistors for interfacing and switching circuits, to various sensors for health and body motion sensing, and to microheaters for temperature delivery. The HMI devices can be not only seamlessly worn by humans but also implemented as prosthetic skin for robotics, which offer intelligent feedback, resulting in a closed-loop HMI system

Can ratoon cropping improve resource use efficiencies and profitability of rice in central China?

Identifying cropping systems with small global warming potential (GWP) per unit of productivity is important to ensure food security while minimizing environmental footprint. During recent decades, double-season rice (DR) systems in central China have progressively shifted into single-crop, middle-season rice (MR) due to high costs and labor requirements of double-season rice. Ratoon rice (RR) has been proposed as an alternative system that reconciliates both high annual productivity and relatively low costs and labor requirements. Here we used onfarm data collected from 240 farmer fields planted with rice in 2016 to evaluate annual energy balance, environmental impact, and net profit of MR, DR, and RR cropping systems in central China. Energy factors, emission values, and commodity prices obtained from literature and official statistics were used to estimate energy balance, GWP, and economic profit. Average annual yield was 7.7, 15.3. and 13.2 Mg ha−1 for MR, DR, and RR systems, respectively. Average total annual energy input (36 GJ ha−1), GWP (9783 kg ha−1), and production cost (3057 $ha−1) of RR were 35–48$ ha−1) than MR. Compared with DR, RR produced statistically similar net energy yield while doubling the net economic return, with 32–42% lower energy input, production costs, and GWP. Consequently, RR exhibited significantly higher net energy ratio and benefit-to-cost ratio, and substantially lower yield-scaled GWP than the other two cropping systems. In the context of DR being replaced by MR, our analysis indicated that RR can be a viable option to achieve both high annual productivity and large positive energy balance and profit, while reducing the environmental impact