Search

This experimental study focuses on the corrosion behavior of aluminum alloys in hydrogen sulfide (H2S) gas and liquid phases. The corrosion behaviors of 3A21, 6061, and 6063 aluminum alloys are investigated via scanning electron microscopy, energy dispersive spectroscopy, and thermogravimetry-differential scanning calorimetry. The results show that the corrosion rates of the three types of aluminum alloys increase with temperature, and the slope of the corrosion rate curve decreases gradually after reaching a certain temperature. At 75 °C, the corrosion rate reached 0.0675 mm/a, 0.0881 mm/a and 0.0613 mm/a in the gas phase, respectively. The corrosion products show white-yellow-gray irregular pits and a honeycomb-like morphology, and the main components are aluminum hydroxide, alumina, and aluminum sulfide. In particular, the 6061 aluminum alloy presents the most severe corrosion in H2S gas. Compared with the H2S gas phase, the corrosion rate in the liquid phase is higher. Additionally, the irregular pitting and honeycomb-like morphologies are more evident. Corrosion becomes more significant as temperature increases. Although the corrosion products in the two phases are composed of the same components, the content in the liquid phase is higher. The heat absorption and mass loss of the corrosion products present the same regularity. This indicates that the corrosion of the H2S liquid phase on the aluminum alloy is more significant than that of the H2S gas phase. [ABSTRACT FROM AUTHOR]

To understand the overpressure transient and flame behavior of CH4/air premixed gas explosion venting in the presence of porous materials, a series of explosion venting tests is conducted in a spherical vessel with a neck. The effects of pore size, porosity, thickness, and properties of porous material on Pstat, Pred, Pburst, and Pext are measured using pressure transmitters, and the image of an exploding venting jet flame passing through porous materials is captured using a high-speed camera. It is shown that the pressure wave at the high-pressure side of the explosion vent is in a critical state when the venting burst membrane ruptures without the porous materials, and the vented jet is confirmed to be under-expanded. The addition of porous materials does not significantly affect Pstat but results in the highest Pburst in porous material Al2O3 50PPI and the highest Pred in porous material SiC 20PPI. This is consistent with the assumption that Pred > Pburst, and that an increase in Pburst corresponds to a decrease in Pred. In addition, Pext is more likely to occur at a position 250–350 mm away from the vent, and as the thickness of the porous materials increases, the possibility of an external explosion overpressure will increase. Moreover, the porous material significantly affects the venting jet flame, and as the thickness of the porous material increases, the shape of the venting jet flame resembles that of a "broom," owing to the dynamic overpressure generated from the flame-porous material interaction. [ABSTRACT FROM AUTHOR]

Proactive caching has emerged as a promising means to accommodate increased demands for wireless capacity. However, studies of proactive caching usually focus on minimizing the overall load of cache-aided networks. How to calculate each user’s caching gain is still an open problem. In this paper, a two-phase cache-aided network is investigated, in which users with heterogeneous preferences are served by a base station through a shared link. Effective throughput is considered as a performance metric, which describes the reduction in each user’s transmission cost. All possible values of effective throughputs achieved by legitimate caching policies form an achievable domain. It is proved that the achievable domain is a convex set and can be characterized by its boundary. A special type of caching policies, termed uncoded placement absolutely-fair (UPAF) caching, is studied. For the two-user case, games are formulated to allocate effective throughput gains for the two users. For the general multiuser case, a UPAF policy is proposed to organize user cooperation. It is shown that users with more concentrated preferences can obtain higher effective throughputs. [ABSTRACT FROM AUTHOR]

In this letter, the problem of monopulse angle estimation error under mainlobe interference for dual- polarization array is investigated. The adaptive monopulse angle estimation considering cross polarization with array beam scanning is analyzed. To reduce the angle estimation error, an adaptive polarization-constrained monopulse approach based on combined constrained cross polarization and main polarization is proposed. The cross polarization of antenna and target signal is not regarded as a source of estimation error which needs to be suppressed in previous literature. Instead, it contributes to the angle estimation here. The proposed method could obtain accurate monopulse angle estimation while suppressing mainlobe interference. Simulation results verify the performance of the proposed method. [ABSTRACT FROM AUTHOR]

One-port magnetic surface acoustic wave (MSAW) resonators are fabricated by stacking multilayered (FeCoSiB/SiO2)n films directly on top of interdigital electrodes. It is shown that the magneto-acoustic response of the MSAW resonators critically depends the hysteresis of ΔE effect. For the magnetic multilayer without induced magnetic anisotropy, the resonance frequency (fR) exhibits a butterfly-like dependence on the external field, therefore, enabling bipolar detection of magnetic field smaller than its coercive field. However, for the magnetic multilayers with induced magnetic anisotropy, butterfly-like or loop-like fR–H curves are measured along the interdigtial electrode fingers or the SAW propagation direction, which can be attributed to the competition between the magnetic field-induced anisotropy and the stress-induced or shape anisotropy. [ABSTRACT FROM AUTHOR]

Data compression is an efficient technique for saving data storage and transmission costs in networks. Traditional data compression methods usually compress each content item according to its own statistical distribution of symbols and do not take into account user preferences on various content items. However, user preferences significantly impact the statistical distributions of symbols transmitted over communication links. This paper presents an edge source coding method to compress data at the network edge, in which codebooks are designed based on not only the statistical distributions of symbols in the content items but also the user preferences. In edge source coding, multiple content items might be compressed via the same codebook. For discrete user preferences, DCA (difference of convex functions programming algorithm) based and $k$ -means++ based algorithms are proposed to derive codebook designs. For continuous user preferences, a sampling method is applied to yield codebook designs. In addition, edge source coding is extended to the two-user case and codebooks are designed to utilize multicasting opportunities. Simulation results demonstrate that edge source coding significantly reduces transmission costs for short content items. [ABSTRACT FROM AUTHOR]

The leakage accidents due to the corrosion on the internal bottom plates occurred frequently in the tanks which are involved in the first commercial direct coal liquefaction production line. For comprehending the corrosion, the compositions of the sedimentary liquids from diesel, hydro‐upgrading feed oil, heavy solvent oil, thick condensed oil and hydro‐stabilizing feed oil are surveyed in the first place, the results show that all the sedimentary liquids are almost neutral; the cations and anions in all sedimentary liquids are the same; the majority of ions are Ca2+, Cl−, and SO42− in these five sedimentary liquids. Then the immersion and electrochemical tests are implemented, it is represented that corrosion of same sedimentary liquid on Q235 steel coupon is severer than that on 16MnR steel coupon; the sedimentary liquid from hydro‐stabilizing feed oil has the most violent causticity; all the corrosives may hold the Fe2CO3 and Fe2O3; the polarization behavior of Q235 steel in the sedimentary liquid from hydro‐stabilizing feed oil is similar to that of 16MnR steel. Finally, the influences of different ions on the corrosivity of sedimentary liquids are also investigated, it can be concluded that the 672‐h general corrosion rates of Q235 and 16MnR steel coupons in all sedimentary liquids increase with improve of Cl‐ content but decrease with rising of SO42− content; in the sedimentary liquids containing large numbers of Cl‐ and Ca2+, the Ca2+ is the definitely vital ion which deeply influences the corrosivity of sedimentary liquids. The achievement of this research work also can be applied in the prevention for corrosion formed on the internal bottom plates of tanks referred to the direct coal liquefaction process. © 2018 American Institute of Chemical Engineers Process Saf Prog 37: 506–517, 2018 [ABSTRACT FROM AUTHOR]

In the coal direct liquefaction process line distribution of finished oil tanks and semifinished oil tanks, corrosion of tank reservoir parts and the gas phase are important. To prove the corrosion‐influencing factors and corrosion processes of various parts of the storage tank, further research was carried out based on the previous research. As the process of corrosion of the tank wall is affected by the sulfur element in oil, the sulfur content in refined oil and semi‐refined oil was analyzed first. The results show that: the sulfur content is high for hydro‐upgrading feed oil and hydro‐stabilizing feed oil, but the sulfur content is low for thick condensed oil and diesel. The tank is mainly made of 16MnR and Q235‐b steel in the process plant. In this article, 16MnR and Q235‐b steel coupons are used for static coupon experiments and electrochemical experiments to determine the influencing factors and processes that affect the corrosion of the reservoir and the gas phase. The static coupon tests show that the corrosion rates are similar for 16MnR and Q235‐b steel coupons in the reservoir location and for the gas‐phase parts. And, the corrosion rates decrease with time. The corrosion rates of 16MnR and Q235‐b steel in hydro‐stabilizing feed oil are relatively high, and the corrosion rates of 16MnR and Q235‐b steel are relatively low, though the difference is not significant. The 16MnR corrosion rate is relatively high in the reservoir location compared to that of the gas phase. The corrosion rate of Q235‐b steel in the gas‐phase space is relatively higher than that of the reservoir location. Electrochemical tests show that the corrosion rates of 16MnR and Q235‐b steel in hydro‐stabilizing feed oil are higher than those in the other three oils. Finally, the effect of temperature on the corrosion rate was studied by the static coupon experiment. The results show that the corrosion rates of 16MnR steel and Q235‐b steel in the four kinds of oil products increase first and then decrease when the temperature changes from 70 to 110°C. The corrosion rate reaches the maximum when the temperature is 90°C. The research of this article can provide some technical support and help for the corrosion protection and safety design of oil tanks in the direct liquefaction process. © 2018 American Institute of Chemical Engineers Process Process Saf Prog 37:419–426, 2018 [ABSTRACT FROM AUTHOR]

Pushing and caching are recognized as promising techniques to improve network capacity and handle explosive growth in data traffic. Caching schemes for synchronous requests have been extensively investigated, but little attention has been paid to the asynchronous case. However, asynchronism is an inherent property of user requests. In this paper, request delay information (RDI) is introduced to characterize the asynchronous user requests. Based on RDI, a coded joint pushing and caching (C-JPC) method is proposed to minimize the network traffic by jointly determining when and which data packets are to be pushed and whether they should be cached. Optimal offline and online C-JPC policies for noncausal and causal RDI can be obtained by solving optimization problems, which however are intractable. Fountain coded caching (FCC) and generalized coded caching (GCC) methods are further proposed to give sub-optimal C-JPC policies with low complexity. In addition, lower and upper bounds on the optimal traffic volume are presented. It is shown that FCC and GCC achieve optimal or near-optimal volumes of traffic in some special cases. Simulation results demonstrate that C-JPC brings significant multicasting gains. [ABSTRACT FROM AUTHOR]

Multicasting can reduce network traffic in multiuser systems by serving multiple users simultaneously. The benefits of multicasting basically come from the overlapping and synchronism of user requests. Pushing and caching are techniques that prestore content items in buffers closer to users based on the prediction of user requests, thereby providing a promising approach to eliminating the asynchronism of user requests and creating multicasting opportunities. This paper studies a multiuser wireless communication system, in which the buffers for caching are deployed in the user terminals. Based on the request delay information (RDI) which describes when the users request content items in a deterministic or statistical way, a joint pushing and caching (JPC) method is presented to schedule the content items pushed by the base station and cached in the user buffers. In this paper, multicasting JPC systems work in two modes, without or with the feedback of RDI. Furthermore, RDI is classified into three forms, namely, noncausal, statistical, and causal. Static and dynamic JPC policies are, respectively, proposed for the two work modes. In addition, the effective throughput resulting from JPC under the three forms of RDI is demonstrated via theoretical analysis and simulation. [ABSTRACT FROM PUBLISHER]

In a Wistar rat model, prolonged supplementation of mustard seed (MS) to the diet significantly ameliorates the induction of colorectal carcinomas by 1,2-dimethylhydrazine (DMH). The expression of the splenocyte major histocompatibility complex class I (MHCI) was found significantly enhanced, whereas that of the major histocompatibility complex class II (MHCII) was significantly decreased. Compared to that of control animals, the proportion of spleenic B- and dendritic cells (DC) was amplified in the MS group. The expressions of MHCI, as well as that of MHCII, were increased in DC cells; whereas in B cells, MHCI expression was augmented but that of MHCII moderately decreased. The percentages of CD8+CD28+ and CD4+CD28+ cells were increased in the MS group, while the CD4+CD25+Foxp3+ subset was depressed. Plasma analysis showed that DMH-exposure induced amplified amounts of interleukin (IL)-4, IL-5, IL-10, and transforming growth factor-beta, whereas MS feeding counteracted this effect but enhanced IL-2, IL12p70, IL21, TNF-alpha, and interferon-gamma. In the SW480 colon adenocarcinoma cell-line, the cytotoxicity of spleenic T-cells from MS-fed animals was significantly increased. In the DMH-exposed rats, the expression of perforin in the spleenic T-cells was dramatically decreased, whereas MS abolished this depression. In summary, dietary MS suppresses DMH-induced immuno-imbalance as well as colon carcinogenesis in rats. [ABSTRACT FROM AUTHOR]

Triphenylacrylonitrile and diarylamine based D–π–A luminogens exhibit typical AIE characteristics with high solid state efficiency up to unity and switchable mechanochromism with high contrast, which render them multifunctional materials for versatile applications in optical storage, volatile organic compound (VOC) detection, OLEDs, etc. [ABSTRACT FROM AUTHOR]

• An accident on corrosion of a polycrystalline distillation column was investigated. • The main corrosion forms are pitting corrosion and stress corrosion caused by Cl−. • Corrosion rate of 316 L stainless steel is negatively correlated with the pH. • Corrosion rate of 316 L stainless steel is positively correlated with temperature. • Transformation from pitting corrosion to stress corrosion occurs at high temperature. Distillation column is a fundamental device for the production of the semiconductor polysilicon. Therefore, investigating corrosion leakage protection of the distillation column is of great significance because of the undetectable yet very significant consequences of corrosion leakage to the column. In this work, corrosion investigation of a polycrystalline silicon rectification tower is presented. The composition and crack morphology of the distillation column (316 L austenitic stainless steel) were detected and analysed using component and hardness analysers. The effects of pH and temperature on the corrosion rate were studied by conducting electrochemical experiments. According to the macroscopic test results, the surface of the tower was covered with a large number of pits and cracks of different depths. Furthermore, based on the metallographic analysis, SEM analysis, and energy spectrum analysis results, it was determined that the crack morphology was mostly intergranular and transgranular. Combined with the test data and process environment, it has been determined that the main forms of corrosion for rectification towers are pitting corrosion and stress corrosion caused by chloride ions. According to the results of electrochemical experiments, the corrosion rate of 316 L stainless steel is negatively correlated with pH value for a pH range of 4–6 at constant temperatures. However, the corrosion rate is positively correlated with temperature for the range of 60 °C–90 °C at constant pH values. From the analysis of the corrosion morphology, the corrosion failure mode of 316 L stainless steel is largely attributed to pitting corrosion when the column is operated at low temperatures (60 °C and 70 °C). However, at high temperatures (90 °C), a transformation from pitting corrosion to stress corrosion occurs along the crystalline form. To ensure the stable operation of the polysilicon rectification tower, this paper proposes corrosion protection measures based on the results of the analysis as described. [ABSTRACT FROM AUTHOR]

Abstract: Perfluorinated sulfonic acid ionomer/poly(N-vinylpyrrolidone) (PFSA/PVP) fibrous membranes with varying compositions were prepared by electrospinning. The morphology, physicochemical structure and water stability of these membranes were investigated by SEM, XRD, and FTIR. The crosslinking agent 4,4′-diazostilbene-2,2′-disulfonic acid disodium salt (DAS) was added to the spinning solutions, and its effect on electrospinning behavior and PFSA/PVP membrane morphology was investigated. Thermal annealing of the DAS-containing PFSA/PVP fibrous membranes resulted in improved water stability due to PVP crosslinking. The adsorption properties of the nanofiber membranes were measured by the ability to remove Cu2+ and Ca2+ ions from water. Nanofiber membranes with higher surface area provide more exposed functional groups and thus better ion removal capability. These functional PFSA/PVP nanofiber membranes show applicability in water treatment and may find potential applications in sensors and drug delivery or as components of the catalytic layer of proton-exchange membrane fuel cells. [Copyright &y& Elsevier]

• The flame evolution behavior of vapor cloud explosion ignited at different positions were analyzed. • Experiments of chained explosions for vertically distributed vapor clouds were conducted. • The effect of vapor cloud diameter and separation distance on the secondary explosion was discussed. • The regime of the enhanced secondary explosion was revealed. Chained explosions happened occasionally, leading to heavy casualties and huge property losses. However, the development regime of the chained explosions is unclear. Experiments of both single and two vertically distributed vapor clouds with different sizes, volume concentrations and ignition conditions were conducted. The experimental results show that the maximum overpressure generated by the primary methane/air mixture explosion increases with vapor diameter, but hardly changes with the ignition energy. The effect of ignition position on chained explosions is significant since the development trajectory of the primary explosion varies with the ignition position. The secondary explosion is more likely to be triggered in the case of ignition at the center of the primary vapor cloud. Because of the enhanced ignition and turbulence induced by the primary explosion, the maximum overpressure and rate of pressure rise of the secondary explosion are larger than that of the primary explosion and increase with a decrease in the separation distance between the two vapor clouds. In addition, the development of the explosion flame for the secondary explosion induced by a primary explosion is asymmetric due to the uncertain ignition point. [ABSTRACT FROM AUTHOR]

An efficient and rapid immunochromatographic assay (ICA) has been engineered for the detection of Streptococcus suis ( S. suis ). The underpinning principle of this ICA test lies in the use of polyclonal antibodies (pAbs) decorated with colloidal gold, which are specific to S. suis. These pAbs were derived from rabbits immunized with type II histidine triad protein (HtpsC) and HtpsC-N of S. suis . The sensitivity of the ICA was noteworthy, identifying S. suis at bacterial concentrations as diminutive as 1.0 × 10 3  CFU/mL. Moreover, the assay demonstrated respectable specificity and did not indicate false positives for other bacterial species ( Escherichia coli , Salmonella , Staphylococcus aureus , Listeria monocytogenes , Streptococcus pyogenes , Streptococcus lactis , or Enterococcus faecalis ). The assay was also capable of detecting multiple S. suis serotypes containing the htpsC gene, including serotypes 1-9, 12, 14, 16 and 23. Nonetheless, the detection of S. suis that lacks the htpsC gene remained beyond the capabilities of this assay. A simultaneous analysis of 16 samples utilizing PCR substantiated the reliability of the ICA test. The assay's results can be procured within a 15-min window, making it a suitable option for field application. Broadly, this study underscores the potential of the HtpsC protein as a target antigen for the detection of S. suis , and proposes that the HtpsC protein be evaluated further in other detection assays specific for S. suis ., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Lu, Wang, Cai, Cao, Lu, Hu, Chen and Xiong.)