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• A newly-designed physical 2D simulator applied for dimethyl ether-steam-assisted gravity drainage. • Dimethyl ether-steam-assisted gravity drainage study with comprehensive experimental parameters and extreme conditions. • This study provides perfect implications for unconventional heavy oil practice. Steam-assisted gravity drainage (SAGD) is a mature heavy oil thermal recovery technology but inherently limited to low recovery efficiency at mid-late stage due to the increasing heat loss in the steam chamber. Here, the dimethyl ether (DME)-assisted SAGD technology and its relevant transport and interfacial properties are specifically investigated through physical 2D heavy oil simulation. A total of four-set physical experiments, with different DME injection ratios, were conducted and compared with the traditional SAGD. The experimental results indicate DME is capable of reducing the heavy oil's viscosity and interfacial tension at high temperatures. Three stages, rising, lateral expansion, and descending stages, are determined in the SAGD steam chamber's development; the mid-late SAGD stage is defined when the steam chamber extends to the caprock boundary. With DME additions at the mid-late SAGD stage, higher oil recovery factor and sweep efficiency could be reached and the dew point temperature of steam chamber's lead decreases by 0.7–1.8 °C. The optimum gas–water ratio is determined to be 3:1, with the fastest oil recovery growth and the highest final cumulative oil-vapor ratio of 0.163. This study provides reliable experimental bases and valuable analyses for the DME-SAGD technology and its application in heavy oil reservoirs. [ABSTRACT FROM AUTHOR]

Effective removal of mercury (Hg) pollutants from contaminated water/wastewater to prevent severe environmental pollution is of great significance due to the extremely high toxicity of Hg. In this study, granular biochar and gravel (control) were packed into intermittently aerated constructed wetland (CW) microcosms to treat Hg(Ⅱ)-containing wastewater over 100 d. The results showed that the biochar-filled CWs exhibited notably better Hg(Ⅱ) removal than the gravel systems by facilitating chemical and microbial Hg(Ⅱ) reduction and volatilization and promoting plant growth and Hg assimilation. More than ten times more Hg was absorbed by the plants (L. salicaria) in biochar CWs than in the gravel systems, with the roots acting as the major sink. In contrast, substrate binding in a predominantly oxidizable fraction was the dominant pathway for Hg removal in the gravel CWs. Biochar substrates also exhibited higher levels of COD, N and P removal, and Hg(Ⅱ) import impacted the removal of these pollutants only slightly. Filling material played a more crucial role than Hg input in shaping the microbial communities in the CWs. The proportions of some dominant genera, including Arenimonas , Lysobacter , Micropruina and Hydrogenophaga , increased in the presence of Hg, implying their tolerance to Hg toxicity and potential roles in Hg detoxification in the CWs. Granular biochar-based CW has high potential for treating Hg(Ⅱ)-contaminated wastewater. [Display omitted] • Granular biochar-filled CWs were applied to treat Hg(Ⅱ)-containing wastewater. • Biochar substrates facilitated Hg volatilization and phytoremediation. • Biochar CWs were more effective in removing COD, N and P than gravel systems. • Hg(Ⅱ) input slightly decreased the nutrient removal efficiencies of CWs. • Effect of Hg on the microbial communities in CWs was related to substrate type. [ABSTRACT FROM AUTHOR]

This paper investigates the multi-sensor distributed fusion with memory configuration for multi-target automatic tracking (MTAT) in clutter. Aimed at fully addressing the problems of both track origin ambiguity and the strong-correlation among system track and its paired local tracks in the framework, this paper derives an Exact Unified Multisensory Tracks Fusion with Memory (EU-MTFwM) method that fuses the system track with enumerated combinatorial tracks to achieve fusing all sensors' local tracks at once. It deploys track-to-track probabilistic association (T2TPA) and target-existence based track automatic management (TAM) to mitigate track origin ambiguity caused by clutter disturbance and the presence of multiple targets. Additionally, it implements the exact distributed kinematic state estimation (exact DKSE) to remove strong correlation stemming from common historical measurements and process noise. However, as the number of sensors to be fused increases, the proposed EU-MTFwM suffers from the combinatorial explosion. An Implementable Unified Multisensory Tracks Fusion with Memory (IU-MTFwM) method is then derived to sequentially fuse the system track with origin-ambiguous local tracks from multiple sensors one-by-one, providing a unified but computationally efficient alternative to the EU-MTFwM. Furthermore, a novel system track initialization technology is proposed to trigger the multisensory tracks fusion recursion. Numerical results show the proposed two unified methods achieve comparable tracking performance to the centralized fusion benchmark but with significantly reduced communication consumption, and demonstrate intensive improvement over the enhanced state-of-the-art that incorporates our proposed system track initialization into its fusion recursion. [ABSTRACT FROM AUTHOR]

In X-ray pulsar-based navigation (XPNAV), the appearance of Doppler effects caused by the dynamic motion of the spacecraft would severely degrade the navigation accuracy. In this paper, we develop a new XPNAV method based on a two-stage estimation method of Doppler frequency and phase delay to overcome the Doppler effects. Based on the pre-established phase model of the pulsar at the SSB and the predicted states of the spacecraft, the real-time phase model at the spacecraft is modeled with respect to the initial position and velocity errors of the spacecraft. It turns out that within an observation interval, a constant Doppler frequency can be estimated to overcome the effect of the initial velocity error, and then the phase delay caused by the initial position error can be estimated by using the computationally efficient methods based on epoch folding. Under this frame, the H-test for uniformity, which needs no prior knowledge of the light curve, is used to estimate the Doppler frequency and the fast maximum likelihood method is used to estimate the phase delay. The dynamic model and measurement model of the proposed navigation method are also given. Photon-level simulation results obtained by using the ground-based semi-physical simulation system for X-ray pulsar signals show a significant improvement over the traditional XPNAV method. [ABSTRACT FROM AUTHOR]

• Interfacial tension value can judge whether the liquid and gas system can be foamed. • Compound surfactant with concentration of 2 wt% has excellent foaming performance. • CO 2 oil-based foam stability deteriorates with increasing temperature and pressure. • Interfacial tension varies with temperature in different pressure ranges. Gas channeling easily occurs in CO 2 flooding, leading to lower oil production efficiency. CO 2 oil-based foam can effectively control gas channeling, so it is particularly important to study the stability of CO 2 oil-based foam to improve oil recovery. In this paper, an oil-based foam system was constructed by evaluating many different surfactants, and then the viscosity of the base oil and the type of gas were changed to study their influence on the stability of the oil-based foam. The stability of CO 2 oil-based foam under high temperature and high pressure was analyzed. Finally, the influence of CO 2 -oil interfacial tension (IFT) on the stability of oil-based foam was investigated. The results show that the CO 2 oil-based foam system composed of compound foaming agent FS with a total concentration of 2 wt% and a ratio of FCO-80 to Span 20 of 3:7 and an oil phase with a viscosity of 2.98 mPa·s have excellent foaming performance. In Zones I and II, the CO 2 -oil IFT is too low, a miscible or near miscible system is formed, and the system cannot generate foam. Although the IFT in Zone III is low, the film's strength is low, which leads to no foam in the system. The temperature and pressure conditions in zone IV are suitable for an oil-based foam system to generate foam. Under the same foam system, there is a critical CO 2 -oil IFT at different temperatures, which can be used as a standard to criterion whether the system can foam. This paper has meaningful guiding significance for improving the stability mechanism of CO 2 oil-based foam under different temperatures and pressures and controlling gas channeling in the process of CO 2 flooding. [ABSTRACT FROM AUTHOR]

In order to address the problem with low signal-to-noise ratio (SNR) detection for airborne magnetic anomaly detection (MAD), an adaptive detection method based on bi-stable stochastic resonance (SR) system is proposed. The method adopts a series structure, S-SR, effectively improving detection speed. Allowing for the difficulty in parameter selection for the SR system, this method can achieve the adaptive selection of system parameters. On this basis, the effect of different sampling frequencies in the Runge–Kutta method on the numerical model of the SR system is investigated. Finally, the simulation and experiment analysis of MAD methods are performed to draw a comparison between the S-SR, orthogonal basis functions (OBF) decomposition, and high-order crossing (HOC) methods. According to the simulation and experiment results, the S-SR method outperforms the OBF and HOC methods in the outcome and range of detection under the same conditions. [Display omitted] • A magnetic anomaly detection method based on bi-stable stochastic resonance system. • A magnetic anomaly signal model of the underwater target. • An adaptive selection method of stochastic resonance system parameters. • The optimization of the numerical model of stochastic resonance system. [ABSTRACT FROM AUTHOR]

A predefined permission source region (PSR) is commonly used in bioluminescence tomography (BLT) as a priori information to reduce the ill-posedness of source reconstruction. However, the PSR is usually hard to determine and may miss the actual source region. Simultaneously, a linear or nonlinear based reconstruction method commonly have a relatively poor performance in the terms of low photon rate and strong noise. Here, we propose an alternative statistical-based-reconstruction framework with a cluster-algorithm-optimized PSR for BLT. In the alternative reconstruction framework, a global reconstruction is first conducted overall the solving domain to generate a rough estimation of source distribution by using a global based maximum likelihood expectation maximum (MLEM) method. Subsequently, a k-means cluster method is used to learn and find likely source support regions, which generates the optimal PSR. Finally, a local MLEM based reconstruction is performed to refine the source distribution on the optimal PSR. We first verify the performance of the proposed method with a series of numerical simulations, and then explore the potential by imaging in situ liver cancer in living mouse. [ABSTRACT FROM AUTHOR]

The Zn 1.8 SiO 3.8 (ZS) ceramics with BaCu(B 2 O 5 ) (BCB) additive were synthesized by the conventional solid-state reaction route and the effect of BCB additive on the microwave dielectric properties of the ceramics was investigated. The results demonstrate that BCB could effectively decrease the sintering temperature from 1300 °C to 930 °C and does not induce obviously degradation of the microwave dielectric properties. The 6.wt% BCB added ZS ceramics exhibited a low sintering temperature (~ 930 °C) and excellent dielectric properties of ε r = 6.79, Q×f = 33,648 GHz, and τ f = −30 ppm/°C. To compensate the negative τ f value of this system, TiO 2 powders were introduced. Particularly when 10.wt% TiO 2 was added, good microwave dielectric properties of ε r = 8.175, Q×f = 21,252 GHz, and τ f = 1.2 ppm/°C were obtained for the 6.wt% BCB added ZS ceramic sintered at 930 °C for 3 h. Moreover, BCB added ZS-TiO 2 ceramics have a chemical compatibility with silver, which indicate that the BCB added ZS ceramics are promising candidate for LTCC applications. [ABSTRACT FROM AUTHOR]

A high performance strontium silicate phosphor has been successfully synthesized though a facile vapor-phase deposition method. The product consists of single crystal whiskers which are smooth and uniform, and with a sectional equivalent diameter of around 5 μm; the aspect ratio is over 50 and no agglomeration can be observed. X-ray diffraction result confirmed that the crystal structure of the whisker was α’-Sr 2 SiO 4 . The exact chemical composition was Sr 1.98 Eu 0.02 SiO 4 which was analyzed by energy dispersive spectrometer and inductively coupled plasma-mass spectrometer. The whisker shows broad green emission with peak at 523 nm ranging from 470 to 600 nm (excited at 370 nm). Compared with traditional Sr 2 SiO 4 :Eu phosphor, durability (at 85% humidity and 85 °C) and thermal stability of the whisker are obviously improved. Moreover, growth mechanism of the Sr 1.98 Eu 0.02 SiO 4 whiskers is Vapor–Liquid–Solid. On a macro-scale, the product is still powder which makes it suitable for the current packaging process of WLEDs. [ABSTRACT FROM AUTHOR]

Abstract: The Co3O4/AAO composite with novel morphology was successfully prepared by the solution-dipping method and the calcination of cobalt acetate precursor at 400°C for 2h in air. Porous anodic alumina (AAO) thin film was selected as new substrate to support colloidal monolayer template. Scanning electron microscopy (SEM) analysis indicated that the morphology of the as-prepared product could be controlled by changing the concentration of precursor. Catalytic test shows that the obtained Co3O4/AAO composite has a high decolorization ratio in the degradation of methylene blue (MB), which reaches 97.79% in 140min in the presence of sodium borohydride (NaBH4). Comparative experiments show that this nanomaterial has enhanced catalytic performance. [Copyright &y& Elsevier]

This paper investigates a novel distributed fusion system for target tracking in three dimensional surveillance using multiple asynchronous BO sensors by simultaneously addressing the problems of target mis-detection and clutter disturbance as well as the out-of-sequence (OOS) information fusion. The proposed distributed fusion architecture consists of the local tracking and distributed fusion, wherein, the refined BO measurements output from the local tracking in each BO sensor are transmitted to the fusion center for subsequent distributed fusion. In the local tracking, instead of kinematic state, the target pseudo state is defined and tracked by operating the proposed pseudo state-integrated probabilistic data association (PS-IPDA) algorithm with an approximately linear pseudo state evolution model, resulting in greatly refined BO sensor measurements. In the fusion center, the sequential asynchronous IPDA-general one-step retrodiction update (SAIPDA-GORU) algorithm is proposed to effectively fuse the transmitted origin-unknown OOS refined measurements (OOSRMs) with the central tracks. The SAIPDA-GORU propagates the central track hybrid state to the OOS time by deploying a general one-step retrodiction technique, and mathematically formulates the OOSRMs-to-retrodicted central track association probabilities utilized to facilitate the fusing of currently filtered central track with OOSRMs. Numerical results show that the proposed PS-IPDA algorithm reduces the errors of target bearings measurement by around a half and eliminates more than 60% of the clutter measurements contained in raw detections, saving significant communication bandwidth between local sensors and fusion center. Furthermore, the proposed SAIPDA-GORU method tangibly improves the estimation accuracy and false track discrimination over the existing discarding method, with the potential to be implemented in real-time. [ABSTRACT FROM AUTHOR]

The phase evolution, thermal stability, structure and magnetic properties of the melt-spun Fe 70− x Pt x B 30 ( x = 0–20) alloys have been investigated. Addition of small amounts of Pt to the Fe 70 B 30 alloy increases the amorphous-forming ability, leading to the formation of an amorphous phase in the alloys with x = 5 and 10. Further increase in Pt content results in the formation of the fcc-FePt + Fe 2 B or fcc-FePt + L 1 0 -FePt + Fe 2 B crystalline phases. After appropriate annealing, the homogeneous nano-sized structure consisting of hard L 1 0 -FePt and soft Fe 2 B magnetic phases were formed for the alloys with x = 10–20, which exhibited good hard magnetic properties. As the Pt content increase, the coercivity ( i H c ) of the L 1 0 -FePt/Fe 2 B nanocomposite alloys significantly increased, while the remanence ( B r ) decreased. The B r , reduced remanence ( M r / M s ), i H c , and energy product ( BH ) max of the alloys are in the range of 0.81–1.20 T, 0.76–0.84, 173.2–523.1 kA/m, and 64.0–88.3 kJ/m 3 , respectively. [ABSTRACT FROM AUTHOR]