Experimental and modeling investigation on separation of methane from coal seam gas (CSG) using hydrate formation

The effects of temperature, pressure, initial promoter concentration and coal seam gas/liquid ratio on the separation of methane from coal seam gas were experimentally investigated. Low temperature, high pressure and high promoter concentration lead to high separation efficiency and high recovery rate of CH 4 , but reduce the CH 4 capture selectivity in hydrate. Experimental simulation of a three-stage separation shows that CH 4 can be concentrated from 34.6 to 81.3 mol% in the dissociated gas, while its content is only 7.2 mol% in the residual gas. An innovative model was established to predict the separation performance. The modeling results reasonably match the experimental data in predicting the effects of different influential factors, with an average relative deviation of 2.83%, the maximum relative deviation 11.2%, and the average relative variance 0.1044. The modeling results of a three-stage separation process include 81.0 mol% of CH 4 in the final dissociated gas and 5.5 mol% of CH 4 in the final residual gas. The recovery rate of CH 4 was 90.1 mol% and the separation factor was 73.0

GNSS Spoofing Identification and Smoothing Localization Method for GNSS/Visual SLAM System

A smoothing localization method for Global Navigation Satellite System (GNSS) and visual Simultaneous Localization and Mapping (SLAM) system is proposed to identify GNSS spoofing, optimize the cumulative error of the GNSS/visual SLAM system, and obtain smoothing localization results. The proposed method analyzes the joint error distribution of the GNSS/visual SLAM system, uses the visual frame to invert the relative error offset of the GNSS from the dimensions of time and localization, performs error analysis and mutual verification based on the verification threshold. According to the mutual verification results, the GNSS spoofing is identified, and the corresponding back-end optimization strategy is selected to obtain a smoothing localization result. Through simulation, the time verification threshold and localization verification threshold of the proposed method are obtained under the condition that the sensors frequency and accuracy are set. The KITTI datasets in rural and urban scenes are used for verification. The simulation results show that our method can identify GNSS spoofing and provide credible and smoothing localization results in the case of GNSS spoofing occurs

Effects of Surfactant and Hydrophobic Nanoparticles on the Crude Oil-Water Interfacial Tension

Surfactants and nanoparticles play crucial roles in controlling the oil-water interfacial phenomenon. The natural oil-wet mineral nanoparticles that exist in crude oil could remarkably affect water-oil interfacial characteristics. Most of recent studies focus on the effect of hydrophilic nanoparticles dispersed in water on the oil-water interfacial phenomenon for the nanoparticle enhanced oil recovery. However, studies of the impact of the oil-wet nanoparticles existed in crude oil on interfacial behaviour are rare. In this study, the impacts of Span 80 surfactant and hydrophobic SiO2 nanoparticles on the crude oil-water interfacial characteristics were studied by measuring the dynamic and equilibrium crude oil-water interfacial tensions. The results show the existence of nanoparticles leading to higher crude oil-water interfacial tensions than those without nanoparticles at low surfactant concentrations below 2000 ppm. At a Span 80 surfactant concentration of 1000 ppm, the increase of interfacial tension caused by nanoparticles is largest, which is around 8.6 mN/m. For high Span 80 surfactant concentrations, the less significant impact of nanoparticles on the crude oil-water interfacial tension is obtained. The effect of nanoparticle concentration on the crude oil-water interfacial tension was also investigated in the existence of surfactant. The data indicates the less significant influence of nanoparticles on the crude oil-water interfacial tension at high nanoparticle concentration in the presence of Span 80 surfactant. This study confirms the influences of nanoparticle-surfactant interaction and competitive surfactant molecule adsorption on the nanoparticles surfaces and the crude oil-water interface

Credible Navigation Algorithm for GNSS Attack Detection Using Auxiliary Sensor System

In order to effectively reduce the impact of Global Navigation Satellite System (GNSS) attacks while providing mobile terminals with credible navigation and positioning results, this paper proposes a credible navigation algorithm for GNSS attack detection using an auxiliary sensor system. Based on a credible Kalman filter and measurement information provided by the auxiliary sensor system on mobile terminals, the proposed algorithm can verify the credibility of the GNSS positioning result and determine whether it has suffered from a GNSS attack using the credible verification window and the credible verification threshold. According to the verification results, the algorithm can adaptively select an updated model for measurement correction and achieve a credible navigation result. The algorithm proposed in this paper has been verified on a self-developed mobile terminal, and the experimental results show that the algorithm can provide credible navigation and positioning services for mobile terminals in the context of GNSS attacks

A Mini Review of <i>S</i>-Nitrosoglutathione Loaded Nano/Micro-Formulation Strategies

As a potential therapeutic agent, the clinical application of S-nitrosoglutathione (GSNO) is limited because of its instability. Therefore, different formulations have been developed to protect GSNO from degradation, delivery and the release of GSNO at a physiological concentration in the active position. Due to the high water-solubility and small molecular-size of GSNO, the biggest challenges in the encapsulation step are low encapsulation efficiency and burst release. This review summarizes the different nano/micro-formulation strategies of a GSNO related delivery system to provide references for subsequent researchers interested in GSNO encapsulation

High-Temperature Reaction Mechanism of Molybdenum Metal in Direct Coal Liquefaction Residue

In this paper, the extraction residue of direct coal liquefaction residue-DCLR(ER) was used as raw material. The high-temperature reaction mechanism of Mo compound in DCLR(ER) was investigated using a synchronous thermal analyzer and the Factsage database. The high temperature reaction of DCLR(ER)-MoO3 in an oxygen atmosphere consists of pyrolysis of organic components at 400&ndash;600 &deg;C, molybdenum trioxide sublimation at 747&ndash;1200 &deg;C, and a stable stage at 600&ndash;747 &deg;C. The thermal reaction process of the DCLR(ER)-MoS2 system in the oxygen atmosphere involves the pyrolysis of unreacted coal and asphaltene, the oxidation of molybdenum sulfide at 349&ndash;606/666 &deg;C, the diffusion of MoO3 at 606/666&ndash;85 &deg;C, and the sublimation reaction process of MoO3 at 854&ndash;1200 &deg;C. The results show that the lower heating rate can promote the oxidation of the Mo compound and the sublimation of molybdenum trioxide. On the other hand, the oxides of aluminum, calcium, and iron in DCLR(ER) can inhibit the oxidative pyrolysis efficiency of the DCLR(ER)-MoS2 system

The Adhesion Strength of Semi-Clathrate Hydrate to Different Solid Surfaces

The adhesion between a hydrate and a pipe wall is the main cause of hydrate deposition and blockage. In this study, the adhesion strength of semi-clathrate hydrate (tetrabutylammonium bromide hydrate) to four kinds of solid surfaces (E235B carbon steel, E355CC low alloy steel, SUS304 stainless steel, and polytetrafluoroethylene) was measured. This investigation reveals that the adhesion strength of the hydrate to a solid surface is negatively correlated with the wettability of the solid surface, which suggests that hydrophobic materials effectively reduced the hydrate adhesion to the pipe wall. The surface roughness showed different effects on the adhesion of the hydrate to hydrophilic or hydrophobic surfaces. To be specific, when the surface roughness increased from 3.2 µm to 12.5 µm, the hydrate adhesion strength to the hydrophilic surface of SUS304 increased by 123.6%, whereas the hydrate adhesion strength to the hydrophobic surface of polytetrafluoroethylene only increased by 21.5%. This study shows that low wettability and low surface roughness effectively reduce the critical rate required to remove hydrate deposition, which achieves the self-removal of hydrates. At the same time, it was found that the adhesion strength of the hydrate to surfaces increases with increasing subcooling. This investigation holds significant theoretical implications for designing self-cleaning surfaces for oil and gas pipes

A 4-bit 36 GS/s ADC with 18 GHz Analog Bandwidth in 40 nm CMOS Process

This paper presents a 4-bit 36 GS/s analog-to-digital converter (ADC) employing eight time-interleaved (TI) flash sub-ADCs in 40 nm complementary metal-oxide-semiconductor (CMOS) process. A wideband front-end matching circuit based on a peaking inductor is designed to increase the analog input bandwidth to 18 GHz. A novel offset calibration that can achieve quick detection and accurate correction without affecting the speed of the comparator is proposed, guaranteeing the high-speed operation of the ADC. A clock distribution circuit based on CMOS and current mode logic (CML) is implemented in the proposed ADC, which not only maintains the speed and quality of the high-speed clock, but also reduces the overall power consumption. A timing mismatch calibration is integrated into the chip to achieve fast timing mismatch detection of the input signal which is bandlimited to the Nyquist frequency for the complete ADC system. The experimental results show that the differential nonlinearity (DNL) and integral nonlinearity (INL) are &minus;0.28/+0.22 least significant bit (LSB) and &minus;0.19/+0.16 LSB, respectively. The signal-to-noise-and-distortion ratio (SNDR) is above 22.5 dB and the spurious free dynamic range (SFDR) is better than 35 dB at 1.2 GHz. An SFDR above 24.5 dB and an SNDR above 18.6 dB across the entire Nyquist frequency can be achieved. With a die size of 2.96 mm * 1.8 mm, the ADC consumes 780 mW from the 0.9/1.2/1.8 V power supply

Secoisolariciresinol diglucoside Ameliorates Osteoarthritis via Nuclear factor-erythroid 2-related factor-2/ nuclear factor kappa B Pathway: In vitro and in vivo experiments

Osteoarthritis (OA) is an age-related joint disease in which inflammation and extracellular matrix (ECM) degradation play a crucial role in the destruction of articular cartilage. Secoisolariciresinol diglucoside (SDG), the main lignan in wholegrain flaxseed, which has been reported to remarkably suppress inflammation and oxidative stress, may have potential therapeutic value in OA. In this study, the effect and mechanism of SDG against cartilage degeneration were verified in the destabilization of the medial meniscus (DMM) and collagen-induced (CIA) arthritis models and interleukin-1β (IL-1β)-stimulated osteoarthritis chondrocyte models. From our experiments, SDG treatment downregulated the expression of pro-inflammatory factors induced by IL-1β in vitro, including inducible nitric oxide synthase (INOS), cyclooxygenase-2 (COX2), tumor necrosis factor (TNF-α), and interleukin 6 (IL-6). Additionally, SDG promoted the expression of collagen II (COL2A1) and SRY-related high-mobility-group-box gene 9(SOX9), while suppressing the expression of a disintegrin and metalloproteinase with thrombospondin motifs 5(ADAMTS5) and matrix metalloproteinases 13(MMP13), which leads to catabolism. Consistently, in vivo, SDG has been identified to have chondroprotective effects in DMM-induced and collagen-induced arthritis models. Mechanistically, SDG exerted its anti-inflammation and anti-ECM degradation effects by activating the Nrf2/HO-1 pathway and inhibiting the nuclear factor kappa B (NF-κB) pathway. In conclusion, SDG ameliorates the progression of OA via the Nrf2/NF-κB pathway, which indicates that SDG may have therapeutic potential for OA

A 12-Bit 2.4 GS/s Four-Channel Pipelined ADC with a Novel On-Chip Timing Mismatch Calibration

This paper presents a 12-bit 2.4 GS/s analog-to-digital converter (ADC) employing four time-interleaved (TI) pipelined channels with a novel on-chip timing mismatch calibration in 40 nm CMOS process. TI architecture can increase the effective sampling rate of ADC but the dynamic performance of TI-ADC system is seriously degraded by offset, gain, and timing mismatches among the channels. Timing mismatch is the most challenging barrier among these mismatches due to the difficulty and complexity of its detection and correction. An automatic wideband timing mismatch detection algorithm is proposed for achieving a wide frequency range of timing mismatch detection without complex calculations. By adopting the proposed mismatch-free variable delay line (VDL), the full-scale traversal timing mismatch correction accomplishes an accurate result without missing codes. Measurement results show that the spurious free dynamic range (SFDR) of the prototype ADC is improved from 55.2 dB to 72.8 dB after calibration at 2.4 GS/s with a 141 MHz input signal. It can achieve an SFDR above 60 dB across the entire first Nyquist band based on the timing mismatch calibration and retiming technology. The prototype ADC chip occupies an area of 3 mm &times; 3 mm and it consumes 420 mW from a 1.8 V supply