520 research outputs found
Some properties on -evaluation and its applications to -martingale decomposition
In this article, a sublinear expectation induced by -expectation is
introduced, which is called -evaluation for convenience. As an application,
we prove that any with some the
decomposition theorem holds and any integrable symmetric
-martingale can be represented as an It integral w.r.t
-Brownian motion. As a byproduct, we prove a regular property for
-martingale: Any -martingale has a quasi-continuous versionComment: 22 page
Exceptional and Anisotropic Transport Properties of Photocarriers in Black Phosphorus
We show that black phosphorus has room-temperature charge mobilities on the
order of 10 cmVs, which are about one order of magnitude
larger than silicon. We also demonstrate strong anisotropic transport in black
phosphorus, where the mobilities along the armchair direction are about one
order of magnitude larger than zigzag direction. A photocarrier lifetime as
long as 100 ps is also determined. These results illustrate that black
phosphorus is a promising candidate for future electronic and optoelectronic
applications.Comment: 5 pages, 4 figure
Exciton-exciton annihilation in MoSe2 monolayers
We investigate the excitonic dynamics in MoSe2 monolayer and bulk samples by
femtosecond transient absorption microscopy. Excitons are resonantly injected
by a 750-nm and 100-fs laser pulse, and are detected by a probe pulse tuned in
the range of 790 - 820 nm. We observe a strong density-dependent initial decay
of the exciton population in monolayers, which can be well described by the
exciton-exciton annihilation. Such a feature is not observed in the bulk under
comparable conditions. We also observe the saturated absorption induced by
exciton phase-space filling in both monolayers and the bulk, which indicates
their potential applications as saturable absorbers.Comment: 5 pages, 4 figure
Multi-objective Optimization of Construction Project Based on Improved Ant Colony Algorithm
It is the key and difficult problem for the current project management to consider the multi-objective optimization of the four elements, such as quality, duration, cost and safety. To improve the accuracy and efficiency of project management during the engineering construction, considering the advantages and disadvantages of the traditional quality-cost-time model, the four elements were regarded as a system, and a multi-objective optimization model was established. The improved ant colony algorithm was used to carry out multi-objectives of construction projects to overcome the premature defect of the traditional method. The optimal plan of the project was found and the overall efficiency of the construction project management was improved. Results show the optimized ant colony algorithm can avoid the low efficiency of the optimal solution search and the shortcoming of the initial pheromone. The engineering practice proves that the enhanced algorithm has solved the problem of the multi-objective optimization of quality, duration, cost and safety. The obtained conclusions are of significant reference value to direct the similar engineering practice
Template free Micro Doppler Signature Classification for Wheeled and Tracked Vehicles
The micro-Doppler signature is a time-varying frequency modulation imparted on radar echo caused by target’s micro-motion. To save the trouble of constructing template in the target classification, this paper investigates the micro-Doppler signature of wheeled and tracked vehicles and proposes a template-free classification method. Firstly, the echo signature is established and the micro-Doppler difference of these two kinds of targets is analysed. Secondly, some new micro-Doppler features are defined according to their difference. The new defined features are micro-Doppler bandwidth, micro-Doppler expansion rate and micro-Doppler peak number. According to the characteristic of the micro-Doppler in the time-frequency domain, we proposed to realise the feature extraction by Hough transformation. Lastly, template-free subjection functions are proposed to define the relationship between the features and the vehicles. By fuzzy comprehensive evaluation, the final classification result is obtained by combining the subjection probabilities together. Experimental results based on the simulated data and measured data are presented, which prove that the algorithm has good performance
- …