Temporal effects in trend prediction: identifying the most popular nodes in the future

Prediction is an important problem in different science domains. In this paper, we focus on trend prediction in complex networks, i.e. to identify the most popular nodes in the future. Due to the preferential attachment mechanism in real systems, nodes' recent degree and cumulative degree have been successfully applied to design trend prediction methods. Here we took into account more detailed information about the network evolution and proposed a temporal-based predictor (TBP). The TBP predicts the future trend by the node strength in the weighted network with the link weight equal to its exponential aging. Three data sets with time information are used to test the performance of the new method. We find that TBP have high general accuracy in predicting the future most popular nodes. More importantly, it can identify many potential objects with low popularity in the past but high popularity in the future. The effect of the decay speed in the exponential aging on the results is discussed in detail

Degree heterogeneity in spatial networks with total cost constraint

Recently, In [Phys. Rev. Lett. 104, 018701 (2010)] the authors studied a spatial network which is constructed from a regular lattice by adding long-range edges (shortcuts) with probability $P_{ij}\sim r_{ij}^{-\alpha}$, where $r_{ij}$ is the Manhattan length of the long-range edges. The total length of the additional edges is subject to a cost constraint ($\sum r=C$). These networks have fixed optimal exponent $\alpha$ for transportation (measured by the average shortest-path length). However, we observe that the degree in such spatial networks is homogenously distributed, which is far different from real networks such as airline systems. In this paper, we propose a method to introduce degree heterogeneity in spatial networks with total cost constraint. Results show that with degree heterogeneity the optimal exponent shifts to a smaller value and the average shortest-path length can further decrease. Moreover, we consider the synchronization on the spatial networks and related results are discussed. Our new model may better reproduce the features of many real transportation systems.Comment: 4 pages, 4 figure

Coevaporation of doped inorganic carrier-selective layers for high-performance inverted planar perovskite solar cells

Inorganic carrier selective layers (CSLs), whose conductivity can be effectively tuned by doping, offer low-cost and stable alternatives for their organic counterparts in perovskite solar cells (PSCs). Herein, we employ a dual-source electron-beam co-evaporation method for the controlled deposition of copper-doped nickel oxide (Cu:NiO) and tungsten-doped niobium oxide (W:Nb2O5) as hole and electron transport layers, respectively. The mechanisms for the improved conductivity using dopants are investigated. Owing to the improved conductivity and optimized band alignment of the doped CSLs, the all-inorganic-CSLs-based PSCs achieves a maximum power conversion efficiency (PCE) of 20.47%. Furthermore, a thin titanium buffer layer is inserted between the W:Nb2O5 and the silver electrode to prevent the halide ingression and improve band alignment. This leads to a further improvement of PCE to 21.32% and a long-term stability (1200 h) after encapsulation. Finally, the large-scale applicability of the doped CSLs by co-evaporation is demonstrated for the device with 1 cm2 area showing a PCE of over 19%. Our results demonstrate the potential application of the co-evaporated CSLs with controlled doping in PSCs for commercialization

Monitoring Water and Energy Cycles at Climate Scale in the Third Pole Environment (CLIMATE-TPE)

A better understanding of the water and energy cycles at climate scale in the Third Pole Environment is essential for assessing and understanding the causes of changes in the cryosphere and hydrosphere in relation to changes of plateau atmosphere in the Asian monsoon system and for predicting the possible changes in water resources in South and East Asia. This paper reports the following results: (1) A platform of in situ observation stations is briefly described for quantifying the interactions in hydrosphere-pedosphere-atmosphere-cryosphere-biosphere over the Tibetan Plateau. (2) A multiyear in situ L-Band microwave radiometry of land surface processes is used to develop a new microwave radiative transfer modeling system. This new system improves the modeling of brightness temperature in both horizontal and vertical polarization. (3) A multiyear (2001–2018) monthly terrestrial actual evapotranspiration and its spatial distribution on the Tibetan Plateau is generated using the surface energy balance system (SEBS) forced by a combination of meteorological and satellite data. (4) A comparison of four large scale soil moisture products to in situ measurements is presented. (5) The trajectory of water vapor transport in the canyon area of Southeast Tibet in different seasons is analyzed, and (6) the vertical water vapor exchange between the upper troposphere and the lower stratosphere in different seasons is presented

Conflict detection and resolution for workflows constrained by resources and non-determined durations

The correctness of a workflow specification is critical for the automation of business processes. Therefore, errors in the specification should be detected and corrected at build-time. In this paper, we present a conflict verification and resolution approach for a kind of workflow constrained by resources and non-determined duration based on Petri net. In this kind of workflow, there are two timing functions for each activity to present the minimum and maximum duration of each activity, and the implementations of some activities require resources. Based on the Petri net model obtained, the earliest time to start each activity can be calculated and the key activities influencing the implementation of the workflow can be determined, with which the resource consistency between activities can be verified. Key-activity and waiting-short priority strategies are adopted to remove the resource conflicts between activities, which can ensure that most of the subsequent activities start as early as possible and that the whole workflow be finished in a shorter time. Through experiments, it is proved that the proposed removal strategy for resource conflicts is better than other strategies