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Passive indoor human localization is the basis for implementing ubiquitous wireless sensing systems.However,commercial WiFi signals are easily affected by the surrounding environment in our life,which makes it difficult for existing WiFi-based indoor localization works to accurately separate the dynamic human components from the complex received signals.To address this problem,this paper proposes the WiPasLoc,a passive indoor human localization system,which achieves high accuracy indoor localization by using the channel state information(CSI) extracted from commercial WiFi devices.Firstly,the Doppler frequency shift(DFS) estimation is carried out in combination with the signal quality of the CSI subcarriers.Then,the target person signal component is precisely separated from the channel state information by using a double-window-based angle of arrival(AoA) estimation method.Finally,combined with the initial position information of the personnel,accurate passive indoor human localization is achieved by the proposed trajectory fitting algorithm.Experimental results show that the median error of WiPasLoc for indoor personnel trajectory positioning is 80cm,which is 25.9% higher than the existing typical Widar2.0 positioning accuracy.

Single-crystalline Mn3O4 nanoflakes were grown on manganese sheets by one-step thermal oxidation process at 360–500 °C in ambient atmosphere. The samples were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), Raman and transmission electron microscope (TEM). The nanoflakes with a size of 15–20 nm in thickness, ~60 nm in width, and ~210 nm in length are obtained at 360 °C for 24 h. A surface diffusion mechanism is proposed to explain the growth of manganese oxide nanostructures via thermal oxidation, which includes two steps: manganese oxide (MnO/Mn3O4) layers form firstly, and then Mn3O4 nanostructures grow above the upper metal oxide layer to form multi-layered structures, MnO/Mn3O4/Mn3O4–nanoflakes. The nucleation and growth of Mn3O4 nanostructures are related to the surface energy and different growth rates along different crystal directions, which are controlled by the diffusion of the metal and gas molecule. [ABSTRACT FROM AUTHOR]

Three chain-based GdIII coordination polymers, namely [Gd2(SO4)3(phen)2(H2O)2]n (1), [Gd2(oda)2(ox)(H2O)6]n (2) and {[Gd2(glu)3(H2O)2]·4H2O}n (3) (phen = 1,10-phenanthroline, H2oda = oxydiacetic acid, H2ox = oxalic acid and H2glu = glutaric acid), have been successfully constructed by using multidentate O ligands under hydro/solvothermal conditions. Complex 1 has a one-dimensional (1D) chain bridged by inorganic sulfate, and complex 2 exhibits a 1D double-chain ladder-shaped structure connected by oxalate. While, complex 3 is a three-dimensional (3D) metal–organic framework composed of 1D chains. All of them display good thermal stabilities and large magnetic entropy changes with −ΔSmaxm ＞ 31 J kg−1 K−1 (7 T), suggesting them to be good candidates for use as cryogenic magnetic refrigerants. [ABSTRACT FROM AUTHOR]

In order to study methane generation yields from different types of crude oil within reservoirs and from residual bitumen within source rocks during thermal cracking process and to determine natural gas genetic types，pyrolysis experimental results in closed gold tube system have been systematically evaluated in the present study. Correlation between methane yields and heating temperatures has been established. Physical properties of crude oil exert critical influence on gas generation temperature and potential. Initial temperatures of gas generation from heavy oil and bitumen are lower than these from light oil and normal oil. In the early stage of oil cracking，methane yield from heavy oil is higher than that from normal oil and light oil. In the main oil cracking stage，methane yield from light oil exceeds normal oil and heavy oil rapidly and becomes the major contributor to gas inventory. Such difference is caused by their chemical compositions.Heavy oil is rich in resins and asphaltenes which have low activation energies so that its cracking to gas is easy，while its low methane yield is controlled by low H/C ratio. Light oil is rich in saturated hydrocarbons which have high activation energies so that its cracking to gas is difficult and starts at Easy% RO=1.5%，whereas its high methane yield is governed by high H/C ratio. The cracking of kerogen and residual bitumen within source rocks share some similarity as crude oils. Methane yield is controlled by H/C ratios with an order of Ⅰ>Ⅱ>Ⅲ in all situations. The chemical compositions of residual bitumen are similar to heavy oil，which is prone to crack at relatively low temperature due to lower activation energy. Meanwhile，clay minerals in source rocks can take a rule as catalyst，which can further facilitate thermal cracking process.Simulation results suggest that thermal cracking of residual bitumen starts at Easy% RO=1.0%. Such difference has significant impact on gas genetic type determination and resource potential evaluation in over matured petroleum systems like Sichuan Basin. [ABSTRACT FROM AUTHOR]