16 research outputs found
An efficient approach of controlling traffic congestion in scale-free networks
We propose and study a model of traffic in communication networks. The
underlying network has a structure that is tunable between a scale-free growing
network with preferential attachments and a random growing network. To model
realistic situations where different nodes in a network may have different
capabilities, the message or packet creation and delivering rates at a node are
assumed to depend on the degree of the node. Noting that congestions are more
likely to take place at the nodes with high degrees in networks with scale-free
character, an efficient approach of selectively enhancing the
message-processing capability of a small fraction (e.g. 3%) of the nodes is
shown to perform just as good as enhancing the capability of all nodes. The
interplay between the creation rate and the delivering rate in determining
non-congested or congested traffic in a network is studied more numerically and
analytically.Comment: 7 pages, 5 figure
New Improvement of Labor Accounting in the Sharing Economy
The investigation of labor is a key aspect of population research, and labor accounting, as its foundation, is an important means to judge the degree of economic development and monitor the changes of the labor market, having always been a focus of scholarly research. At present, the sharing economy is on the rise worldwide and influences labor accounting. In this paper, starting from the context of the sharing economy and the current situation of labor accounting, several important aspects of labor accounting will be discussed. In the context of the sharing economy, household subsistence service production is to be included in the production accounting boundary, which is the root of the changes in labor accounting. On this basis, the following findings are drawn. (1) The scope of accounting for employment should be expanded, which puts higher demands on the labor accounting method. (2) Working time should be remeasured, especially indicators based on pay time. (3) Finally, the design of indicators in labor underutilization also requires the formation of new ideas, especially unemployment should be redefined. Finally, in view of the current status of labor accounting in China, policy suggestions for future improvement under the sharing economy are put forward
A China Railway Express-Based Model for Designing a Cross-Border Logistics Information Cloud Platform Scheme
This paper describes the development and plans for the implementation of a cloud-based logistics platform to enable and optimize cross-border shipping, using the China Railway Express (CR Express) in the context of China’s recent One Belt and One Road (OBOR) initiative as an example of an extremely complex system that is running at suboptimal efficiency. We design a cross-border logistics information cloud platform (CLICP) and its architecture. The proposed CLICP comprises a hybrid cloud model with three layers of cloud services. We also examine the CLICP’s operation and the design of the platform’s functions, including core business and value-added service functions, such as real-time bidding, freight information push, and carrier one-stop service management functions. Finally, we propose a model for deploying our CLICP. Our study makes a significant contribution to the literature because of its hybrid cloud model architecture and for the completeness of its functionality. The study also has a good application prospect for the operation of CR Express and will play a better supporting role in cross-border logistics
The Optimization of Urban Traffic Routes Using an Enhanced Genetic Algorithm: A Case Study of Beijing South Railway Station
Optimizing travel routes in urban transportation networks is essential for enhancing traffic efficiency in major cities. This study focuses on optimizing the combined subway and taxi travel routes from Beijing Union University to Beijing South Railway Station, a critical route for students and staff in Beijing. To address this, we propose three genetic algorithms: the Standard Genetic Algorithm (SGA), the Multipoint Crossover and Elitist Selection Genetic Algorithm (MPEGA), and the Improved Dynamic Crossover and Mutation Rate Genetic Algorithm (IDCMGA). Experimental results indicate that MPEGA reduces the mean travel cost by 15.21%, the variance by 81.72%, and the standard deviation by 57.25% compared to SGA. Additionally, IDCMGA reduces the average by 1.76%, the variance by 63.16%, and the standard deviation by 39.30% compared to MPEGA. The improved IDCMGA algorithm demonstrates significant advantages over the other two algorithms in terms of global optimization capability, convergence speed, and stability, and is more adept at adapting to new traffic conditions to identify the optimal route. Optimizing this route not only reduces commuting time and costs but also alleviates traffic congestion, thereby enhancing the overall efficiency of the urban transportation system
Identifying Urban structure based on transit-oriented development
The fast development of urbanization has led to imbalances in cities, causing congestion, pollution, and urban sprawl. In response to the growing concern over the distribution of demand and supply, a more coordinated urban structure is addressed in comprehensive planning processes. In this study, we attempt to identify urban structure using a Network-Activity-Human model under the Transit-Oriented Development (TOD) concept, since TOD is usually regarded as an urban spatial planning tool. In order to explore the strengths and weaknesses of the urban structure, we define the TOD index and unbalance degree and then classify the urban areas accordingly. We take the city of Beijing as a case study and identify nine urban types. The results show a hierarchical urban structure: the city center covers most of the hotspots which display higher imbalances, the surroundings of the city center are less developed, and the city edges show higher potentials in both exploitation and transportation development. Moreover, we discuss the extent to which the spatial scale influences the unbalance degree and apply a sensitivity analysis based on the goals of different stakeholders. This methodology could be utilized at any study scale and in any situation, and the results could offer suggestions for more accurate urban planning, strengthening the relationship between TOD and spatial organization.Transport and Plannin
Ultrahigh Energy Density in SrTiO<sub>3</sub> Film Capacitors
Solid-state
dielectric film capacitors with high-energy-storage density will further
promote advanced electronic devices and electrical power systems toward
miniaturization, lightweight, and integration. In this study, the
influence of interface and thickness on energy storage properties
of SrTiO<sub>3</sub> (STO) films grown on La<sub>0.67</sub>Sr<sub>0.33</sub>MnO<sub>3</sub> (LSMO) electrode are systematically studied.
The cross-sectional high resolution transmission electron microscopy
reveals an ion interdiffusion layer and oxygen vacancies at the STO/LSMO
interface. The capacitors show good frequency stability and increased
dielectric constant with increasing STO thickness (410–710
nm). The breakdown strength (<i>E</i><sub>b</sub>) increases
with decreasing STO thickness and reaches 6.8 MV/cm. Interestingly,
the <i>E</i><sub>b</sub> under positive field is enhanced
significantly and an ultrahigh energy density up to 307 J/cm<sup>3</sup> with a high efficiency of 89% is realized. The enhanced <i>E</i><sub>b</sub> may be related to the modulation of local
electric field and redistribution of oxygen vacancies at the STO/LSMO
interface. Our results should be helpful for potential strategies
to design devices with ultrahigh energy density
Electric-Field-Controlled Nonvolatile Magnetization Rotation and Magnetoresistance Effect in Co/Cu/Ni Spin Valves on Piezoelectric Substrates
Electric-field
control of magnetism is a key issue for the future development of
low-power spintronic devices. By utilizing the opposite strain responses
of the magnetic anisotropies in Co and Ni films, a Co/Cu/Ni/0.7Pb(Mg<sub>1/3</sub>Nb<sub>2/3</sub>)O<sub>3</sub>-0.3PbTiO<sub>3</sub> (PMN-PT)
spin-valve/piezoelectric heterostructure with ∼7 nm Cu spacer
layer was properly designed and fabricated. The purely electric-field-controlled
nonvolatile and reversible magnetization rotations in the Co free
layer were achieved, whereas the magnetization of the Ni fixed layer
was almost unchanged. Accordingly, not only the electroresistance
but also the electric-field-tuned magnetoresistance effects were obtained,
and more importantly at least six nonvolatile magnetoresistance states
in the strain-tuned spin valve were achieved by setting the PMN-PT
into different nonvolatile piezo-strain states. These findings highlight
potential strategies for designing electric-field-driven multistate
spintronic devices
Interfacial Ion Intermixing Effect on Four-Resistance States in La<sub>0.7</sub>Sr<sub>0.3</sub>MnO<sub>3</sub>/BaTiO<sub>3</sub>/La<sub>0.7</sub>Sr<sub>0.3</sub>MnO<sub>3</sub> Multiferroic Tunnel Junctions
A multiferroic tunnel
junction (MFTJ), employing a ferroelectric barrier layer sandwiched
between two ferromagnetic layers, presents at least four resistance
states in a single memory cell and therefore opens an avenue for the
development of the next generation of high-density nonvolatile memory
devices. Here, using the all-perovskite-oxide La<sub>0.7</sub>Sr<sub>0.3</sub>MnO<sub>3</sub>/BaTiO<sub>3</sub>/La<sub>0.7</sub>Sr<sub>0.3</sub>MnO<sub>3</sub> as a model MFTJ system, we demonstrate asymmetrical
MnTi sublattice intermixing at the La<sub>0.7</sub>Sr<sub>0.3</sub>MnO<sub>3</sub>/BaTiO<sub>3</sub> interfaces by direct local
measurements of the structure and valence, which reveals the relationship
between ferroelectric polarization directions and four-resistance
states, and the low temperature anomalous tunneling behavior in the
MFTJ. These findings emphasize the crucial role of the interfaces
in MFTJs and are quite important for understanding the electric transport
of MFTJs as well as designing high-density multistates storage devices