25 research outputs found
Lithium-Excess Research of Cathode Material Li2MnTiO4 for Lithium-Ion Batteries
Lithium-excess and nano-sized Li2+xMn1−x/2TiO4 (x = 0, 0.2, 0.4) cathode materials were synthesized via a sol-gel method. The X-ray diffraction (XRD) experiments indicate that the obtained main phases of Li2.0MnTiO4 and the lithium-excess materials are monoclinic and cubic, respectively. The scanning electron microscope (SEM) images show that the as-prepared particles are well distributed and the primary particles have an average size of about 20–30 nm. The further electrochemical tests reveal that the charge-discharge performance of the material improves remarkably with the lithium content increasing. Particularly, the first discharging capacity at the current of 30 mA g−1 increases from 112.2 mAh g−1 of Li2.0MnTiO4 to 187.5 mAh g−1 of Li2.4Mn0.8TiO4. In addition, the ex situ XRD experiments indicate that the monoclinic Li2MnTiO4 tends to transform to an amorphous state with the extraction of lithium ions, while the cubic Li2MnTiO4 phase shows better structural reversibility and stability
Research on the protection and reuse of industrial heritage from the perspective of public participation—a case study of northern mining area of Pingdingshan, China
With the decline of the big industrial period, many industrial cities in China are facing the problem of urban transformation. Post-industrial economic activities and social life often replace the demand for land and population growth, and the particular type of cultural heritage of industrial heritage is often abandoned and decayed. Recent domestic and foreign research has responded to this problem and sought to provide solutions for the protection and reuse of industrial heritage. Despite some progress, the advice and feelings of ordinary citizens are often rarely considered, or how local urban characteristics become the core of urban reconstruction. To solve this problem, the focus of this study is the case study of Pingdingshan City. Pingdingshan is an industrial city with coal as its core industry. Shortly, the problem of industrial heritage will be a severe problem facing the city. The study included research designs and methods for collecting data from field observations, questionnaires, interviews, and literature studies. In the process, researchers have critically considered the importance and implications of public participation in exploring the way in which they are protected and reused through the protection and reuse of industrial heritage. It is particularly worth mentioning that in the reconstruction of the protection and reuse of industrial heritage in Pingdingshan, government officials and enterprises lack sensitivity to local conditions and the views of residents. The study concluded that the protection and reuse of industrial heritage require public participation and that the public’s demands can guide and determine the way industrial heritage is protected and reused
Real-time Monitoring for the Next Core-Collapse Supernova in JUNO
Core-collapse supernova (CCSN) is one of the most energetic astrophysical
events in the Universe. The early and prompt detection of neutrinos before
(pre-SN) and during the SN burst is a unique opportunity to realize the
multi-messenger observation of the CCSN events. In this work, we describe the
monitoring concept and present the sensitivity of the system to the pre-SN and
SN neutrinos at the Jiangmen Underground Neutrino Observatory (JUNO), which is
a 20 kton liquid scintillator detector under construction in South China. The
real-time monitoring system is designed with both the prompt monitors on the
electronic board and online monitors at the data acquisition stage, in order to
ensure both the alert speed and alert coverage of progenitor stars. By assuming
a false alert rate of 1 per year, this monitoring system can be sensitive to
the pre-SN neutrinos up to the distance of about 1.6 (0.9) kpc and SN neutrinos
up to about 370 (360) kpc for a progenitor mass of 30 for the case
of normal (inverted) mass ordering. The pointing ability of the CCSN is
evaluated by using the accumulated event anisotropy of the inverse beta decay
interactions from pre-SN or SN neutrinos, which, along with the early alert,
can play important roles for the followup multi-messenger observations of the
next Galactic or nearby extragalactic CCSN.Comment: 24 pages, 9 figure
Constructing Repairable Meta-Structures of Ultra-Broad-Band Electromagnetic Absorption from Three-Dimensional Printed Patterned Shells
Ultra-broad-band
electromagnetic absorption materials and structures are increasingly
attractive for their critical role in competing with the advanced
broad-band electromagnetic detection systems. Mechanically soft and
weak wax-based materials composites are known to be insufficient to
serve in practical electromagnetic absorption applications. To break
through such barriers, here we developed an innovative strategy to
enable the wax-based composites to be robust and repairable meta-structures
by employing a three-dimensional (3D) printed polymeric patterned
shell. Because of the integrated merits from both the dielectric loss
wax-based composites and mechanically robust 3D printed shells, the
as-fabricated meta-structures enable bear mechanical collision and
compression, coupled with ultra-broad-band absorption (7–40
and 75–110 GHz, reflection loss  smaller than −10
dB) approaching state-of-the-art electromagnetic absorption materials.
With the assistance of experiment and simulation methods, the design
advantages and mechanism of employing such 3D printed shells for substantially
promoting the electromagnetic absorption performance have been demonstrated.
Therefore, such universal strategy that could be widely extended to
other categories of wax-based composites highlights a smart stage
on which high-performance practical multifunction meta-structures
with ultra-broad-band electromagnetic absorption could be envisaged
Graphene-Based Sandwich Structures for Frequency Selectable Electromagnetic Shielding
Due
to substantial development of electronics and telecommunication techniques,
materials with electromagnetic interference (EMI) shielding performance
are significant in alleviating the interference impacts induced from
a remarkable variety of devices. In the work, we propose novel sandwich
structures for manipulating the EM wave transport, which holds unique
EMI shielding features of frequency selectivity. By employing electrical
and magnetic loss spacers, the resultant sandwich structures are endowed
with tunable EMI shielding performance, showing substantial improvements
in overall shielding effectiveness along with pronounced shielding
peak shift. The mechanisms suggest that the multiple interfaces, electromagnetic
loss media, and changes of representative EM wavelength could be critical
roles in tailoring the EMI shielding performance. The results provide
a versatile strategy that could be extended in other frequency ranges
and various types of sandwich structures, promising great opportunities
for designing and fabricating advanced electromagnetic attenuation
materials and devices