arXiv subjects

Ning Li

Publications and source records attributed to Ning Li.

At least 199 records · Page 11Linked to original sources

arXiv2019

Sputtered Spontaneously Nano-porous VO2-based Films via PTFE Self-Template: Localized Surface Plasmon Resonance Induced Robust Optical Performance for Solar Glazing Application

The PTFE (Teflon) has been selected as the self-template structural material in preparation of VO2 films using reactive magnetron sputtering systems and post annealing progress. Spontaneous random nano-porous structures of VO2 films growing on quartz glasses have been deliberately established via bottom-up processing through this novel and facile approach. The nano-porous VO2 films exhibit an excellent optical performance based on localized surface plasmon resonance (LSPR), with ultrahigh luminous transmittance (Tlum) up to 78.0% and the promoted solar modulation ability (ΔTsol) of 14.1%. Meanwhile, the ingenious microstructure of film provides an antireflection function from multiple perspectives in visible light, with the potential of the windshield on vehicles for smart solar modulation. The nano-porous films expand the practical application of thermochromic VO2 to a fire-new field, breaking the optical performance envelope of single-layer dense VO2 film away, and offering a universal method to prepare homogeneous nano-porous structures for thin films.

physics.app-ph↗

arXiv2019

Towards Commercializing Vanadium Dioxide Films: Investigation of the Impact of Different Interface on the Deterioration Process for Largely Extended Service Life

Long term stability is the most pressing issue that impedes commercialization of Vanadium Dioxide (VO2) based functional films, which show a gradual loss of relative phase transition performance, especially in humid conditions when serving as smart windows. Here, we investigated the impact of different interface on the deterioration process of VO2 films and proposed a novel encapsulation structure for largely extended service life. Hydrophobic and stable hafnium dioxide (HfO2) layers have been incorporated with VO2 films for encapsulated surfaces and cross sections. With modified thickness and structure of HfO2 layers, the degradation process of VO2 can be effectively suppressed. The proposed films can retain stable phase transition performances under high relative humidity (90%) and temperature (60 Celsius) over 100 days, which is equal to about 16 years in the real environment. Improving the stability of VO2 materials is a necessary step towards commercializing production of high performance films for long term use.

physics.app-ph↗

arXiv2019

Galilean invariance restoration on the lattice

We consider the breaking of Galilean invariance due to different lattice cutoff effects in moving frames and a nonlocal smearing parameter which is used in the construction of the nuclear lattice interaction. The dispersion relation and neutron-proton scattering phase shifts are used to investigate the Galilean invariance breaking effects and ways to restore it. For $S$-wave channels, ${}^1S_0$ and ${}^3S_1$, we present the neutron-proton scattering phase shifts in moving frames calculated using both Lüscher's formula and the spherical wall method, as well as the dispersion relation. For the $P$ and $D$ waves, we present the neutron-proton scattering phase shifts in moving frames calculated using the spherical wall method. We find that the Galilean invariance breaking effects stemming from the lattice artifacts partially cancel those caused by the nonlocal smearing parameter. Due to this cancellation, the Galilean invariance breaking effect is small, and the Galilean invariance can be restored by introducing Galilean invariance restoration operators.

nucl-th↗

arXiv2018

Atomic Structure of Polar Surface in SrTiO3

Rearrangement of atoms due to broken translational symmetries at the surface of SrTiO$_3$ is scarcely debatable in the present day scenario. Actual concern demands to unveil the true structure and precise mechanism responsible for atomic reconstructions at a unit cell level. Here, we reveal the atomic structure of SrTiO$_3$ surface by using annular bright field imaging in spherical aberration corrected scanning transmission electron microscope. We measure structural parameters such as lattice constant, bond length, atomic displacement and subsequently we find a polarization for the top five unit cells is ~10-20 uCcm$^{-2}$. Both Sr-O and Ti-O planes reconstruct thus contribute to net dipole moment that is towards surface. Elongation of the out of plane lattice for skin layers is also witnessed. The electron energy loss spectroscopy experiment illustrates the presence of oxygen vacancies at the surface which seems to be largely responsible for the stability of surface polarization. Our study provides a sound foundation into mechanistic understanding for structure and properties of surfaces for complex oxides. These outcomes can be considered as a pragmatic boost particularly for examining other insulator-like materials as well as in bridging gap for hitherto fewer experimental investigation along with various theoretical studies.

cond-mat.mtrl-sci↗

arXiv2018

Probing lattice vibration at surface and interface of SiO$_2$/Si with nanometer resolution

Recent advances in monochromatic aberration corrected electron microscopy make it possible to detect the lattice vibration with both high-energy resolution and high spatial resolution. Here, we use sub-10 meV electron energy loss spectroscopy to investigate the local vibrational properties at surface and interface of an amorphous SiO$_2$ (a-SiO$_2$) thin film on Si substrate. We find that each optical mode splits into three sub-modes, i.e., surface mode, bulk mode and interface mode, which can be measured from different locations. The pure surface modes can be measured in the vacuum near the surface, and the pure interface modes are expected to be obtained either at the interface location or in the Si, while inside the SiO$_2$ the measured signal is a mixture of bulk, surface, and interface modes. The bulk mode has the largest vibration energy and surface mode has the lowest. The energy of surface mode is thickness dependent, showing a blue-shift as z-thickness (parallel to fast electron beam) of SiO$_2$ film increases, while the bulk and interface modes have constant vibration energy. The intensity of bulk mode linearly increases with thickness being increased, and it drops steeply to zero near the surface and interface (within a few nanometers). The surface modes decay slowly in the vacuum following a Bessel function. The mechanism of the observed spatially dependent vibration behavior is discussed and quantitatively compared with dielectric response theory analysis. Our nanometer scale measurements of vibrations properties provide useful information about the bonding conditions at the surface and interface and thus may help to design better silicon-based electronic devices via surface and interface treatments

cond-mat.mtrl-sci↗

arXiv2018

Neutron-proton scattering with lattice chiral effective field theory at next-to-next-to-next-to-leading order

We present a new lattice formulation of chiral effective field theory interactions with a simpler decomposition into spin channels. With these interactions the process of fitting to the empirical scattering phase shifts is simplified, and the resulting lattice phase shifts are more accurate than in previous studies. We present results for the neutron-proton system up to next-to-next-to-next-to-leading order for lattice spacings of $1.97$, $1.64$, $1.32$, and $0.99~{\rm fm}$. Our results provide a pathway to $\textit{ab initio}$ lattice calculations of nuclear structure, reactions, and thermodynamics with accurate and systematic control over the chiral nucleon-nucleon force.

nucl-th↗

arXiv2018

Possible hadronic molecules composed of the doubly charmed baryon and nucleon

We perform a systematical investigation of the possible deuteron-like bound states with configuration $Ξ_{cc}N (\bar{N})$, where $N(\bar{N})$ denotes the nucleon (anti-nucleon), in the framework of the one-boson-exchange-potential model. In the spin-triplet sector we take into account both the ${}^3S_1$ and ${}^3D_1$ channels due to non-vanishing tensor force. There exist several candidates of the loosely bound molecular states for the $Ξ_{cc}N$ and $Ξ_{cc}\bar{N}$ systems, which lie below the threshold of $Λ_cΛ_c$ or $Λ_c{\barΛ}_c$. We also investigate the possible loosely bound states with configurations $Λ_cN(\bar{N})$ and $Σ_cN(\bar{N})$. These molecular candidates may be searched for at Belle II and LHC in the near future.

hep-ph↗

arXiv2018

Quantitative and functional post-translational modification proteomics reveals that TREPH1 plays a role in plant thigmomorphogenesis

Plants can sense both intracellular and extracellular mechanical forces and can respond through morphological changes. The signaling components responsible for mechanotransduction of the touch response are largely unknown. Here, we performed a high-throughput SILIA (stable isotope labeling in Arabidopsis)-based quantitative phosphoproteomics analysis to profile changes in protein phosphorylation resulting from 40 seconds of force stimulation in Arabidopsis thaliana. Of the 24 touch-responsive phosphopeptides identified, many were derived from kinases, phosphatases, cytoskeleton proteins, membrane proteins and ion transporters. TOUCH-REGULATED PHOSPHOPROTEIN1 (TREPH1) and MAP KINASE KINASE 2 (MKK2) and/or MKK1 became rapidly phosphorylated in touch-stimulated plants. Both TREPH1 and MKK2 are required for touch-induced delayed flowering, a major component of thigmomorphogenesis. The treph1-1 and mkk2 mutants also exhibited defects in touch-inducible gene expression. A non-phosphorylatable site-specific isoform of TREPH1 (S625A) failed to restore touch-induced flowering delay of treph1-1, indicating the necessity of S625 for TREPH1 function and providing evidence consistent with the possible functional relevance of the touch-regulated TREPH1 phosphorylation. Bioinformatic analysis and biochemical subcellular fractionation of TREPH1 protein indicate that it is a soluble protein. Altogether, these findings identify new protein players in Arabidopsis thigmomorphogenesis regulation, suggesting that protein phosphorylation may play a critical role in plant force responses.

q-bio.GN↗

arXiv2018

Cross-layer Balanced and Reliable Opportunistic Routing Algorithm for Mobile Ad Hoc Networks

For improving the efficiency and the reliability of the opportunistic routing algorithm, in this paper, we propose the cross-layer and reliable opportunistic routing algorithm (CBRT) for Mobile Ad Hoc Networks, which introduces the improved efficiency fuzzy logic and humoral regulation inspired topology control into the opportunistic routing algorithm. In CBRT, the inputs of the fuzzy logic system are the relative variance (rv) of the metrics rather than the values of the metrics, which reduces the number of fuzzy rules dramatically. Moreover, the number of fuzzy rules does not increase when the number of inputs increases. For reducing the control cost, in CBRT, the node degree in the candidate relays set is a range rather than a constant number. The nodes are divided into different categories based on their node degree in the candidate relays set. The nodes adjust their transmission range based on which categories that they belong to. Additionally, for investigating the effection of the node mobility on routing performance, we propose a link lifetime prediction algorithm which takes both the moving speed and moving direction into account. In CBRT, the source node determines the relaying priorities of the relaying nodes based on their utilities. The relaying node which the utility is large will have high priority to relay the data packet. By these innovations, the network performance in CBRT is much better than that in ExOR, however, the computation complexity is not increased in CBRT.

cs.NI↗

arXiv2018

Distributed Joint Offloading Decision and Resource Allocation for Multi-User Mobile Edge Computing: A Game Theory Approach

Due to the spectrum reuse in small cell network, the inter-cell interference has great effect on MEC's performance. In this paper, for reducing the energy consumption and latency of MEC, we propose a game theory based jointing offloading decision and resource allocation algorithm for multi-user MEC. In this algorithm, the transmission power, offloading decision, and mobile user's CPU capability are determined jointly. We prove that this game is an exact potential game and the NE of this game exists and is unique. For reaching the NE, the best response dynamic is applied. We calculate the best responses of these three variables. Moreover, we investigate the properties of this algorithm, including the convergence, the computation complexity, and the price of anarchy. The theoretical analysis shows that the inter-cell interference has great effect on the performance of MEC. The NE of this game is Pareto efficiency and also the global optimal solution of the proposed optimal issue. Finally, we evaluate the performance of this algorithm by simulation. The simulation results illustrates that this algorithm is effective on improving the performance of the multi-user MEC system.

cs.IT↗

arXiv2018

Self-Supervised Adversarial Hashing Networks for Cross-Modal Retrieval

Thanks to the success of deep learning, cross-modal retrieval has made significant progress recently. However, there still remains a crucial bottleneck: how to bridge the modality gap to further enhance the retrieval accuracy. In this paper, we propose a self-supervised adversarial hashing (\textbf{SSAH}) approach, which lies among the early attempts to incorporate adversarial learning into cross-modal hashing in a self-supervised fashion. The primary contribution of this work is that two adversarial networks are leveraged to maximize the semantic correlation and consistency of the representations between different modalities. In addition, we harness a self-supervised semantic network to discover high-level semantic information in the form of multi-label annotations. Such information guides the feature learning process and preserves the modality relationships in both the common semantic space and the Hamming space. Extensive experiments carried out on three benchmark datasets validate that the proposed SSAH surpasses the state-of-the-art methods.

cs.CV↗

arXiv2017

Detection and Attention: Diagnosing Pulmonary Lung Cancer from CT by Imitating Physicians

This paper proposes a novel and efficient method to build a Computer-Aided Diagnoses (CAD) system for lung nodule detection based on Computed Tomography (CT). This task was treated as an Object Detection on Video (VID) problem by imitating how a radiologist reads CT scans. A lung nodule detector was trained to automatically learn nodule features from still images to detect lung nodule candidates with both high recall and accuracy. Unlike previous work which used 3-dimensional information around the nodule to reduce false positives, we propose two simple but efficient methods, Multi-slice propagation (MSP) and Motionless-guide suppression (MLGS), which analyze sequence information of CT scans to reduce false negatives and suppress false positives. We evaluated our method in open-source LUNA16 dataset which contains 888 CT scans, and obtained state-of-the-art result (Free-Response Receiver Operating Characteristic score of 0.892) with detection speed (end to end within 20 seconds per patient on a single NVidia GTX 1080) much higher than existing methods.

cs.CV↗

arXiv2017

Ab initio calculations of the isotopic dependence of nuclear clustering

Nuclear clustering describes the appearance of structures resembling smaller nuclei such as alpha particles (4He nuclei) within the interior of a larger nucleus. While clustering is important for several well-known examples, much remains to be discovered about the general nature of clustering in nuclei. In this letter we present lattice Monte Carlo calculations based on chiral effective field theory for the ground states of helium, beryllium, carbon, and oxygen isotopes. By computing model-independent measures that probe three- and four-nucleon correlations at short distances, we determine the shape of the alpha clusters and the entanglement of nucleons comprising each alpha cluster with the outside medium. We also introduce a new computational approach called the pinhole algorithm, which solves a long-standing deficiency of auxiliary-field Monte Carlo simulations in computing density correlations relative to the center of mass. We use the pinhole algorithm to determine the proton and neutron density distributions and the geometry of cluster correlations in 12C, 14C, and 16C. The structural similarities among the carbon isotopes suggest that 14C and 16C have excitations analogous to the well-known Hoyle state resonance in 12C.

nucl-th↗

arXiv2017

Efficient and Reliable Topology Control based Opportunistic Routing Algorithm for WSNs

The opportunistic routing has advantages on improving the packet delivery ratio between source node and candidate set (PDRsc). However, considering the frequent topology variation in wireless sensor networks, how to improve and control the PDR has not been investigated in detail. Therefore, in this paper, we propose an efficient and reliable topology control based opportunistic routing algorithm (ERTO) which takes PDRsc into account. In ERTO, the interference and transmission power loss are taken into account during the calculation of PDRsc. The PDRsc, the expected energy consumption, and the relationship between transmission power and node degree are considered to calculate the optimal transmission power and relay node degree jointly. For improving the routing effective and reducing the calculation complexity, we introduce the multi-objective optimization into the topology control. During the routing process, nodes calculate the optimal transmission power and relay node degree according to the properties of Pareto optimal solution set, by which the optimal solutions can be selected. Based on these innovations, the energy consumption, the transmission delay, and the throughout have been improved greatly compared with the traditional power control based opportunistic routing algorithms.

cs.NI↗

arXiv2017

Delay based Duplicate Transmission Avoid (DDA) Coordination Scheme for Opportunistic routing

Since the packet is transmitted to a set of relaying nodes in opportunistic routing strategy, so the transmission delay and the duplication transmission are serious. For reducing the transmission delay and the duplicate transmission, in this paper, we propose the delay based duplication transmission avoid (DDA) coordination scheme for opportunistic routing. In this coordination scheme, the candidate relaying nodes are divided into different fully connected relaying networks, so the duplicate transmission is avoided. Moreover, we propose the relaying network recognition algorithm which can be used to judge whether the sub-network is fully connected or not. The properties of the relaying networks are investigated in detail in this paper. When the fully connected relaying networks are got, they will be the basic units in the next hop relaying network selection. In this paper, we prove that the packet delivery ratio of the high priority relaying nodes in the relaying network has greater effection on the relaying delay than that of the low priority relaying nodes. According to this conclusion, in DDA, the relaying networks which the packet delivery ratios of the high priority relaying nodes are high have higher priority than that of the low one. During the next hop relaying network selection, the transmission delay, the network utility, and the packet delivery ratio are taken into account. By these innovations, the DDA can improve the network performance greatly than that of ExOR and SOAR.

cs.NI↗

arXiv2017

Probability Prediction based Reliable Opportunistic (PRO) Routing Algorithm for VANETs

In the Vehicular ad hoc networks (VANETs), due to the high mobility of vehicles, the network parameters change frequently and the information which the sender maintains may outdate when it wants to transmit data packet to the receiver, so for improving the routing effective, we propose the probability prediction based reliable (PRO) opportunistic routing for VANETs. The PRO routing algorithm can predict the variation of Signal to Interference plus Noise Ratio (SINR) and packet queue length (PQL) in the receiver. The prediction results are used to determine the utility of each relaying vehicle in the candidate set. The calculation of the vehicle utility is weight based algorithm and the weights are the variances of SINR and PQL of the candidate relaying vehicles. The relaying priority of each relaying vehicle is determined by the value of the utility. By these innovations, the PRO can achieve better routing performance (such as the packet delivery ratio, the end-to-end delay, and the network throughput) than the SRPE, ExOR (street-centric), and GPSR routing algorithms.

cs.NI↗

arXiv2017

Phase shift formulas for baryon-baryon scattering in elongated boxes

We have established the relations between the baryon-baryon scattering phase shifts and the two-particle energy spectrum in the elongated box. We have studied the cases with both the periodic boundary condition and twisted boundary condition in the center of mass frame. The framework is also extended to the system of nonzero total momentum with periodic boundary condition in the moving frame. This will be helpful to extract the phase shifts in the continuum from lattice QCD data using asymmetric volumes.

nucl-th↗

arXiv2017

Deuteron-like states composed of two doubly charmed baryons

We present a systematic investigation of the possible molecular states composed of a pair of doubly charmed baryons ($Ξ_{cc}Ξ_{cc}$) or one doubly charmed baryon and one doubly charmed antibaryon $(Ξ_{cc}\barΞ_{cc})$ within the framework of the one-boson-exchange-potential model. For the spin-triplet systems, we take into account the mixing between the ${}^3S_1$ and ${}^3D_1$ channels. For the baryon-baryon system $Ξ_{cc}Ξ_{cc}$ with $(R,I) = (\bar{3}, 1/2)$ and $(\bar{3}, 0)$, where $R$ and $I$ represent the group representation and the isospin of the system, respectively, there exist loosely bound molecular states. For the baryon-antibaryon system $Ξ_{cc}\barΞ_{cc}$ with $(R,I) = (8, 1)$, $(8, 1/2)$ and $(8,0)$, there also exist deuteron-like molecules. The $B_{cc}\bar{B}_{cc}$ molecular states may be produced at LHC. The proximity of their masses to the threshold of two doubly charmed baryons provides a clean clue to identify them.

hep-ph↗