177 research outputs found
Designing Enhanced Multi-dimensional Constellations for Code-Domain NOMA
This paper presents an enhanced design of multi-dimensional (MD)
constellations which play a pivotal role in many communication systems such as
code-domain non-orthogonal multiple access (CD-NOMA). MD constellations are
attractive as their structural properties, if properly designed, lead to signal
space diversity and hence improved error rate performance. Unlike the existing
works which mostly focus on MD constellations with large minimum Euclidean
distance (MED), we look for new MD constellations with additional feature that
the minimum product distance (MPD) is also large. To this end, a non-convex
optimization problem is formulated and then solved by the convex-concave
procedure (CCCP). Compared with the state-of-the-art literature, our proposed
MD constellations lead to significant error performance enhancement over
Rayleigh fading channels whilst maintaining almost the same performance over
the Gaussian channels. To demonstrate their application, we also show that
these MD constellations give rise to good codebooks in sparse code multiple
access systems. All the obtained MD constellations can be found in
https://github.com/Aureliano1/Multi-dimensional-constellation
Metabolic Profiling Analysis of the Alleviation Effect of Treatment with Baicalin on Cinnabar Induced Toxicity in Rats Urine and Serum
Objectives: Baicalin is the main bioactive flavonoid constituent isolated from Scutellaria baicalensis Georgi. The mechanisms of protection of liver remain unclear. In this study, 1H NMR-based metabonomics approach has been used to investigate the alleviation effect of Baicalin.Method:1H NMR metabolomics analyses of urine and serum from rats, was performed to illuminate the alleviation effect of Baicalin on mineral medicine (cinnabar)-induced liver and kidney toxicity.Results: The metabolic profiles of groups receiving Baicalin at a dose of 80 mg/kg were remarkably different from cinnabar, and meanwhile, the level of endogenous metabolites returned to normal compared to group cinnabar. PLS-DA scores plots demonstrated that the variation tendency of control and Baicalein are apart from Cinnabar. The metabolic profiles of group Baicalein were similar to those of group control. Statistics results were confirmed by the histopathological examination and biochemical assay.Conclusion: Baicalin have the alleviation effect to the liver and kidney damage induced by cinnabar. The Baicalin could regulate endogenous metabolites associated with the energy metabolism, choline metabolism, amino acid metabolism, and gut flora
Deterministic generation of skyrmions and antiskyrmions by electric current
Magnetic skyrmions are nanoscale spin whirlpools that promise breakthroughs
in future spintronic applications. Controlled generation of magnetic skyrmions
by electric current is crucial for this purpose. While previous studies have
demonstrated this operation, the topological charge of the generated skyrmions
is determined by the direction of the external magnetic fields, thus is fixed.
Here, we report the current-induced skyrmions creation in a chiral magnet FeGe
nanostructure by using the \emph{in-situ} Lorentz transmission electron
microscopy. We show that magnetic skyrmions or antiskyrmions can be both
transferred from the magnetic helical ground state simply by controlling the
direction of the current flow at zero magnetic field. The force analysis and
symmetry consideration, backed up by micromagnetic simulations, well explain
the experimental results, where magnetic skyrmions or antiskyrmions are created
due to the edge instability of the helical state in the presence of spin
transfer torque. The on-demand generation of skyrmions and control of their
topology by electric current without the need of magnetic field will enable
novel purely electric-controlled skyrmion devices.Comment: 5 pages and 4 figure
Designing Enhanced Multidimensional Constellations for Code-Domain NOMA
This letter presents an enhanced design of multi- dimensional (MD) constellations which play a pivotal role in many communication systems such as code-domain non- orthogonal multiple access (CD-NOMA). MD constellations are attractive as their structural properties, if properly designed, lead to signal space diversity and hence improved error rate performance. Unlike the existing works which mostly focus on MD constellations with large minimum Euclidean distance (MED), we look for new MD constellations with additional feature that the minimum product distance (MPD) is also large. To this end, a non-convex optimization problem is formulated and then solved by the convex-concave procedure (CCCP). Compared with the state-of-the-art literature, our proposed MD constellations lead to significant error performance enhancement over Rayleigh fading channels whilst maintaining almost the same performance over the Gaussian channels. To demonstrate their application, we also show that these MD constellations give rise to good codebooks in sparse code multiple access systems
Metabolic Profiling Analysis of the Alleviation Effect of the Fractions of Niuhuang Jiedu Tablet on Realgar
Niuhuang Jiedu Tablet (NJT) is a classical formula in treating acute tonsillitis, pharyngitis, and so on. In the formula, significant level of Realgar as a potentially toxic element is contained. Our previous experiments revealed that it was less toxic for combined Realgar in NJT. However, the active fraction of this prescription with toxicity alleviation effect on Realgar was still obscure. NJT was divided into five different polar fractions (NJT-PET, NJT-25, NJT-50, NJT-75, and NJT-95), and we explored the toxicity alleviation effect on Realgar. Based on 1H NMR spectra of urine and serum from rats, PCA and PLS-DA were performed to identify different metabolic profiles. Liver and kidney histopathology examinations and serum clinical chemistry analysis were also performed. With pattern recognition analysis of metabolites in urine and serum, Realgar group showed a clear separation from control group, while the metabolic profiles of NJT-PET, NJT-25, NJT-50, and NJT-95 groups were similar to Realgar group, and the metabolic profiles of NJT and NJT-75 groups were very close to control group. Statistics results were confirmed by the histopathological examination and biochemical assay. The present work indicated that 75% EtOH fraction of NJT was the most valid fraction with the toxicity alleviation effect on Realgar
A Novel Non-Coherent SCMA With Massive MIMO
The synergistic amalgamation of sparse code multiple access (SCMA) and multiple-input multiple-output (MIMO) technologies can be exploited for improving spectral efficiency and providing enhanced wireless services to massive users. In this case, however, channel estimation is a burning issue with the increasing number of users and/or antennas. To tackle this problem, we propose a novel non-coherent transmission scheme for SCMA, referred to as NC-SCMA. In the proposed NC-SCMA, each user first maps its binary data to sparse codewords, and then perform differential modulation on the non-zero dimensions. Upon receiving all users’ signals, we leverage the channel hardening effect to carry out differential demodulation and multi-user detection without any instantaneous channel state information. In addition, the design of the sparse codebooks in the NC-SCMA system is investigated with the aid of the pair-wise probability. Numerical results demonstrate the superiority of the proposed technique over the benchmark scheme in terms of bit error rate performance
Research on the ZigBee Network and Equipment Design Based on the CC2530
It is known to us all that embedded systems designed on the 51 chip microcomputer are mature. This research finished to plant the system from 51 chip microcomputer to the CC2530 chip of TI. After analyzing and mastering the ZigBee 2007 PRO protocol stack, a new set of wireless sensor network (WSN) products has been developed. In the system, the coordinator can establish the Mesh network on its own initiative and the child nodes can join the network. The coordinator can be connected to the personal computer or the embedded gateway. The gateway had the Ethernet port and can send the data from the sensors to the cable or wireless network. The operator can issue instructions automatically and manually. The information of the sensor nodes can be returned and displayed on the serial debugging assistant. The equipment has passed the test with different environments in which there are obstacles among the communicating sensors and can be applied in the traffic, environmental monitoring and other fields widely
Pressure-induced Superconductivity in Zintl Topological Insulator SrIn2As2
The Zintl compound AIn2X2 (A = Ca, Sr, and X = P, As), as a theoretically
predicted new non-magnetic topological insulator, requires experiments to
understand their electronic structure and topological characteristics. In this
paper, we systematically investigate the crystal structures and electronic
properties of the Zintl compound SrIn2As2 under both ambient and high-pressure
conditions. Based on systematic angle-resolved photoemission spectroscopy
(ARPES) measurements, we observed the topological surface states on its (001)
surface as predicted by calculations, indicating that SrIn2As2 is a strong
topological insulator. Interestingly, application of pressure effectively tuned
the crystal structure and electronic properties of SrIn2As2. Superconductivity
is observed in SrIn2As2 for pressure where the temperature dependence of the
resistivity changes from a semiconducting-like behavior to that of a metal. The
observation of nontrivial topological states and pressure-induced
superconductivity in SrIn2As2 provides crucial insights into the relationship
between topology and superconductivity, as well as stimulates further studies
of superconductivity in topological materials.Comment: 15 pages,5 figure
- …