1,066 research outputs found
A Comment on "Memory Effects in an Interacting Magnetic Nanoparticle System"
Recently, Sun et al reported that striking memory effects had been clearly
observed in their new experiments on an interacting nanoparticle system [1].
They claimed that the phenomena evidenced the existence of a spin-glass-like
phase and supported the hierarchical model. No doubt that a particle system may
display spin-glass-like behaviors [2]. However, in our opinion, the experiments
in Ref. [1] cannot evidence the existence of spin-glass-like phase at all. We
will demonstrate below that all the phenomena in Ref. [1] can be observed in a
non-interacting particle system with a size distribution. Numerical simulations
of our experiments also display the same features.Comment: A comment on "Phys. Rev. Lett. 91, 167206
Expertise diversity of teams predicts originality and long-term impact in science and technology
Despite the growing importance of teams in producing innovative and
high-impact science and technology, it remains unclear how expertise diversity
among team members relates to the originality and impact of the work they
produce. Here, we develop a new method to quantify the expertise distance of
researchers based on their prior career histories and apply it to 23 million
scientific publications and 4 million patents. We find that across science and
technology, expertise-diverse teams tend to produce work with greater
originality. Teams with more diverse expertise have no significant impact
advantage in the short- (2 years) or mid-term (5 years). Instead, they exhibit
substantially higher long-term impact (10 years), increasingly attracting
larger cross-disciplinary influence. This impact premium of expertise diversity
among team members becomes especially pronounced when other dimensions of team
diversity are missing, as teams within the same institution or country appear
to disproportionately reap the benefits of expertise diversity. While
gender-diverse teams have relatively higher impact on average, teams with
varied levels of gender diversity all seem to benefit from increased expertise
diversity. Given the growing knowledge demands on individual researchers,
implementation of incentives for original research, and the tradeoffs between
short-term and long-term impacts, these results may have implications for
funding, assembling, and retaining teams with originality and long-lasting
impacts.Comment: 31 pages, 5 figure
Effects of Cryogenic Treatment after Annealing of Ti-6Al-4V Alloy Sheet on Its Formability at Room Temperature
© 2018 by the authors. Licensee MDPI, Basel, Switzerland. This is an Open Access article made available under the terms of the Creative Commons Attribution licence CC BY 4.0 (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited.In this article, the effects of cryogenic treatment after annealing on the formability of Ti-6Al-4V alloy sheet were experimentally studied. The Ti-6Al-4V titanium alloy was treated by cryogenic treatment after annealing (ACT). Tensile tests were carried out using a universal machine at room temperature. The microstructure evolution of Ti-6Al-4V subjected to ACT was also investigated using an optical microscope (OM). Both the shearing performance and drawing formability were analyzed by punch shearing tests and deep drawing tests, respectively. Results showed that after ACT, the tendency of the β phase can be apparently changing into stable β’ and α’ phases. The elastic modulus is lower than that of the untreated material. It was found that both the yield strength and tensile strength are declined slightly, whereas the ductility is increased significantly. The shear strength in punch shearing is decreased at room temperature and cryogenic temperature. The ratio of smooth zone on the section after ACT3 is much larger than the others. The rollover diameters are not obviously greater than those of the untreated. Additionally, the height of the burr shows a decreasing trend after ACT. During deep drawing, drawing depth is deeper than that of the untreated material, the drawing load after ACT is reduced, and the decreasing tendency of the drawing load slows down. It is noted that the micro-cracks occur at the bottom of the sample.Peer reviewe
New control strategy against temperature sudden-drop in the initial stage of pad cooling process in poultry houses
Preliminary field measurements have shown substantial temperature sudden-drop (ΔTsd) at bird level in the initial stage of pad cooling process in arid regions of China. Such sudden temperature fluctuation can cause thermal stress to laying hens and this problem is attracting increasing concerns. The purpose of this study was to develop a new control strategy (NCS) to avoid or minimize ΔTsd while simplify the operational process. Theoretical calculation and field test were conducted in this study. The key ambient thermal factor affecting ΔTsd was analysed by calculating temperature drop of cooled air existing the cooling pad (ΔTd). A countermeasure was applied by controlling the wetted pad area at each startup of the water supply pump. Field test was carried out to demonstrate application of the NCS in a poultry house. The theoretical arithmetic results showed that ambient relative humidity (RHo) was the main factor affecting ΔTd, and ΔTsd occurred when RHo ≤ 60%. Temperature fluctuation at the bird level (Tdb,b) could be controlled within 4°C when the wetted pad area increased by 25%. The NCS operated based on RHo that was divided into three regions. For RHo \u3e 80%, the pump would not be turned on because of poor cooling effect. For 60% \u3c RHo \u3c 80%, no ΔTsd would occur and the pump would be controlled by “on-off” regulation. For RHo ≤ 60%, ΔTsd occurred and the pump was turned on intermittently. Then, 4-stage cooling would be applied. Results of the field test were generally consistent with the theoretical simulation with regards to alleviation of ΔTsd that was controlled within 3.5°C. Further field verification of the NCS on the flock health and production performance is warranted
Probabilistic activity driven model of temporal simplicial networks and its application on higher-order dynamics
Network modeling characterizes the underlying principles of structural
properties and is of vital significance for simulating dynamical processes in
real world. However, bridging structure and dynamics is always challenging due
to the multiple complexities in real systems. Here, through introducing the
individual's activity rate and the possibility of group interaction, we propose
a probabilistic activity driven (PAD) model that could generate temporal
higher-order networks with both power-law and high-clustering characteristics,
which successfully links the two most critical structural features and a basic
dynamical pattern in extensive complex systems. Surprisingly, the power-law
exponents and the clustering coefficients of the aggregated PAD network could
be tuned in a wide range by altering a set of model parameters. We further
provide an approximation algorithm to select the proper parameters that can
generate networks with given structural properties, the effectiveness of which
is verified by fitting various real-world networks. Lastly, we explore the
co-evolution of PAD model and higher-order contagion dynamics, and analytically
derive the critical conditions for phase transition and bistable phenomenon.
Our model provides a basic tool to reproduce complex structural properties and
to study the widespread higher-order dynamics, which has great potential for
applications across fields
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