The cement-based materials widely used in infrastructure construction, such as bridges and ports, are subjected to seawater erosion and medium erosion during their service life, and their durability has always been a concern. The diffusion coefficient of chloride ions is an important indicator in the research of cement-based materials’ durability, and the pore structure is one of the most fundamental reasons affecting the diffusion behavior of chloride ions. In this paper, Mercury intrusion porosimetry (MIP), Nuclear magnetic resonance (NMR), and Nitrogen adsorption method (NAD) were used to analyze the pore structures of mortars with different volume fractions of sands. The relationship between mortar pore structure and chloride ion diffusion coefficient was established to predict its chloride ion diffusion coefficient. It may provide a new idea for studying the durability of cement-based materials. Results indicated that similar to cement paste, the pore structure of mortar satisfied the fractal characteristics of solid phase within a certain range of pores. The most probable gel pore diameter of mortars with different sand volume fractions was about 4 nm, while the most probable capillary pore diameter was approximately 46 nm, and the critical pore diameter was ranging from 50 to 60 nm. MIP results indicated that with the increase in sand volume fraction (ϕagg), the total porosity (fmip) of the mortar decreased, satisfying the relationship of fmip = 0.1859 − 0.0789ϕagg. However, the porosity of the matrix (fbase) increased with the increase in sand volume fraction, which was due to the introduction of more interfaces by the addition of aggregates. The effective chloride ion diffusion coefficient (Dcp,base) of the matrix can be obtained by fitting. Based on this, the interface transition zone (ITZ) and the cement matrix were comprehensively considered as a whole fractal phase. The predicted value of the chloride ion diffusion coefficient obtained by the Mori–Tanaka homogenization method was in good agreement with the results obtained from rapid chloride migration (RCM) experiments, and the maximum error between the simulated and experimental values did not exceed 11%. This finding can provide new ideas for accurately predicting the chloride ion diffusion coefficient of mortar and even concrete.

In this study, a new three-dimension model for simulating the cooling and drying process of moist air on the airside of fin-and-tube heat exchangers in the heat pump was established using the finite element method. Comparing the simulation results with the experimental results, the average absolute percentage errors of outlet temperature and moisture content are 3.08% and 5.1%, respectively, which prove that the simulation model has high accuracy. Based on this, the influence of different simulation boundary conditions on the heat transfer of moist air was investigated. The boundary conditions for the normal airflow range were optimized to constant heat flux for resimulation, and the average absolute percentage errors of outlet temperature decreased from 4.12% previously to 1.54%, and which of outlet moisture content decreased from 6.17% previously to 3.64%. The findings of this study provide a reference for establishing more accurate heat transfer simulation models.

Flexible and tunable radar absorbers (RAs) are in great demand both in stealth technologies and electromagnetic delusion for concealment of complex targets such as aircraft and unmanned aerial vehicle from radar detection. As a general approach, conventional lumped components such as varactor diodes and resistors are employed to achieve frequency and/or amplitude tunability of RAs. However, despite the intricate feeding networks and complex fabrication processes, this approach shows great difficulty in integrating the conventional rigid components with flexible substrate. Hence, it is an enormous challenge to realize both dual-tunable and flexible RAs. Here the authors for the first time design and experimentally characterize a flexible and dual-tunable RA with independent control of the frequency and amplitude. Most important is that the achieving both amplitude and frequency control is fully based on the tunability of graphene, without any lumped devices and intricate feeding network, and even without any metal involved. Hence, this dual-tunable RA shows the priority of being flexible, light weight, and environmentally friendly. Although the prototype in this work is operating in microwave spectrum, the tunable functionalities at millimeter or terahertz spectral bands can also be obtained due to the intrinsic tunability of graphene.

Magnetic manganese-iron modified attapulgite sorbents (xMnFAy) were synthesized and employed for Hg-0 removal from coal-fired flue gas. The effects of calcination temperature, MnO2 loading amount, reaction temperature, as well as the individual flue gas components on Hg-0 removal were investigated. The 0.1MnFA loaded with 10 wt% MnO2 and calcined at 450 degrees C exhibited the optimal Hg-0 removal activity, above 80% Hg-0 removal at a high GHSV of 4 x 10(5) h(-1)center dot O-2 promoted Hg-0 removal via recovering surface oxygen and high valence metal ions (Fe3+ and Mn4+). NO improved Hg-0 capture due to the formation of adsorbed NO2 and nitrate species, which functioned as active sites for mercury oxidation. SO2 prohibited Hg-0 retention because of its competitive adsorption against Hg-0 for the active sites and the sulfation of the sorbent. Besides, SO2 could reduce the high valence metal ions to a lower valence, which hampers Hg-0 oxidation. The presence of NO could overcome the inhibitive effect of SO2 on Hg-0 removal because the adsorbed NO2 and nitrate species were still retained on the sorbent surface in the case of SO2 existence center dot H2O inhibited Hg-0 removal because of the competitive adsorption. 0.1MnFA could maintain its good Hg-0 retention ability after five regeneration cycles. This work contributes to developing the cost-effective sorbents for Hg-0 removal from coal-fired flue gas, as well as maximizing the utilization of attapulgite clay.

To remove Hg-0 from coal combustion flue gas efficiently and economically, a magnetically recoverable sorbent fabricated by incorporating gamma-Fe2O3 into attapulgite and subsequently being loaded with CuCl2 was developed and employed for Hg-0 removal in a fixed-bed reactor. Results indicated that 0.05-CuFA could eliminate more than 88% of Hg-0 from the SFG with HCl or not at 150 degrees C under GHSV of 2 x 10(6)h(-1). The surface O* and Cl* species were responsible for Hg-0 oxidation, and the products of mercury were mainly HgO and HgCl2. O-2 contributed to Hg-0 removal by regenerating the consumed O* and re-oxidizing the Cu+ and Fe2+. NO and SO2 both insignificantly affected Hg-0 removal over 0.05CuFA, because CuCl2 could hinder the reaction of NO and SO2 with the surface-active sites, leading to no nitrite species and few sulfate species produced on the surface. The reaction between HCl and the sorbent surface, and the generation of active Cl* was less sensitive to SO2. The co-presence of HCl and O-2 was conducive to recovering the spent sorbent to its raw ability, and made the 0.05CuFA sustain 6 regeneration cycles. From the above advantageous aspects, this work provides an approach for cost-effectively utilizing mineral for Hg-0 decontamination in coal combustion flue gas, and a universal mindset for exploring the Hg-0 removal mechanism.

In this paper, a transparent and flexible absorber using graphene is presented, in which the frequency of the resonant absorption can be modulated in Ku band. The proposed absorber contains a four-layer structure including the patterned graphene capacitor, the periodical striper layer, the polydimethylsiloxane (PDMS) layer and a metallic wire grid ground. By tuning the bias voltage applying to the graphene capacitor, the resonance frequency can be dynamically and continuously shifted from 16.7GHz to 14.6GHz according to the experimental measurement. The optically transparent and structurally flexible characteristics provide more flexibility for applications in electromagnetic stealth and electromagnetic protection of transparent optical components.

In this paper, a systematic study on the growth process of CVD graphene was conducted. Then the optimized growth parameters of CVD graphene were obtained through orthogonal experiment. And the direct corresponding relationship between growth parameters and the sheet resistance of graphene band was given by parametric comparison experiment and formula fitting. The result in this paper established a bridge between basic research and application of graphene in microwave band.

通过在凹凸棒土(Atp)表面负载铁氧化物进行磁改性而生成的磁性凹凸棒土(MAtp),相对于一般脱汞吸附剂而言,更易分离回收,具有实际应用的前景,但脱汞效率较低.本文选取磁质量分数为50％的MAtp,采用浸渍法对其进行CuCl2改性,在利用固定床实验系统上探究了CuCl2负载量、反应温度和烟气组分(O2、SO2、NO、HCl)对其脱汞性能的影响,结合多种表征结果分析其脱汞机理.结果表明:CuCl2负载量的最佳值为5％;一定范围内反应温度与脱汞效率呈正相关,超过250℃时吸附剂的孔隙结构会遭到破坏,发生脱附现象;O2和HCl对吸附剂脱汞性能有明显提升,NO影响较小,SO2会与Hg0竞争吸附,抑制效果显著;CuCl2改性后的MAtp脱汞性能优良,同时延续了较好的磁分离特性,为选择高效实用的脱汞吸附剂提供了研究方向.

The purpose of this paper is to introduce an image processing method to recognize the flame during the experiment for measuring oxygen index of self-supporting specimens. Two strategies are separately applied for two sections of the flame outline by analyzing the characteristics of the combustion image. The brighter part is identified by the secondary OSTU segmentation method dealing with the reflection interference of the glass tube, in which histogram analysis is adapted to determine the threshold enhancement coefficient; For milder contours at the bottom of flame, the segmentation in HSV color space takes effect on the recognition of relevant contours. The combination of the two results accurately forms the entire flame position which contributes to the monitoring process of the oxygen index experiment.

A magnetically recoverable composite mercury removal sorbent was produced by introducing magnetic gamma-Fe2O3 into attapulgite (ATT) (xFe1ATT) via the co-precipitation method and used to remove Hg-0 in the simulated coal-fired power plant flue gas. The as-prepared 0.5Fe1ATT sorbent was characterized by X-ray diffraction, Brunauer-Emmett-Teller, transmission electron microscopy, vibrating sample magnetometer, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy analyses. The results showed that the Hg-0 removal performance of the composite of gamma-Fe2O3 and ATT was significantly promoted in comparison to pure gamma-Fe2O3 and ATT individually. A relatively high magnetization value and good Hg-0 removal performance were obtained by the sample of 0.5Fe1ATT. O-2 could enhance Hg-0 removal activity via the Mars-Maessen mechanism. NO displayed a significant promotion effect on Hg-0 removal as a result of the formation of active species, such as NO2 and NO+. SO2 inhibited the removal of Hg-0 as a result of its competition adsorption against Hg-0 for the active sites and the sulfation of the sorbent. However, the introduction of NO could obviously alleviate the adverse effect of SO2 on the Hg-0 removal capability. H2O showed a prohibitive effect on Hg-0 removal as a result of its competition with Hg-0 for the active sites. The findings of this study are of fundamental importance to the development of efficient and economic magnetic mercury sorbents for Hg-0 removal from coal-fired boiler flue gases.

In this work, the MIL101-Cr sorbent with a large BET surface area was prepared and used to remove He from simulated coal-fired boiler flue gas. The chemical and physical properties of the prepared sorbent were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) analysis, and X-ray photoelectron spectroscopy (XPS). A range of experiments was conducted in a fixed-bed reactor to investigate the effects of reaction temperature, Hg-0 inlet concentration, gas hourly space velocity (GHSV), and flue gas composition on the Hg-0 removal for the prepared sorbent. The mechanisms and kinetics of the Hg-0 adsorption were also studied. The results showed that the MIL101-Cr sorbent achieved a Hg-0 removal efficiency of more than 85% for 4 hat 200 degrees C under the conditions of a relatively high Hg-0 inlet concentration (203 mu g/m(3)) and GHSV (8 x 10(5) h(-1)). The O-2 in the flue gas was found to be beneficial for Hg-0 removal. The NO in the flue gas favored He removal both in the presence and absence of O-2. The SO2 in the flue gas notably inhibited Hg-0 adsorption in the absence of O-2, whereas a low concentration of SO2 slightly inhibited He removal in the presence of O-2. However, high concentrations of SO2 in the flue gas still significantly weakend Hg-0 removal ability, even in the presence of O-2, due to the competitive adsorption of SO2 with Hg-0 on the sorbent and the sulfation of the sorbent. The simultaneous presence of O-2 and NO in the flue gas could overcome the adverse impact of SO2 on Hg-0 adsorption. The H2O has little influence on Hg-0 removal due to the competitive adsorption. XPS analysis indicated that the surface Cr3+, oxygen species, and C=O group in MIL101-Cr acted as the active adsorption/oxidation sites for Hg-0. The Hg-0 removal by MIL101-Cr was due to chemisorption and could be described by the pseudo-second-order model. The equilibrium adsorption capacity calculated for the sorbent amounted to 25 656 mu g/g at 200 degrees C, which indicated that MIL101-Cr could be used as a promising sorbent to remove Hg-0 from coal-fired boiler flue gas.

对自然界中广泛存在的凹凸棒土( Atp)进行磁改性,通过沉积-沉淀法制备出磁性氧化铁改性的磁性凹凸棒土(MAtp),采用BET、VSM、XRD以及SEM等手段对其理化性质加以分析,并在固定床实验台上进行模拟烟气脱汞性能测试,研究了铁氧化物含量、反应温度和烟气成分对其除汞能力的影响.结果表明,Atp与磁性物质的复合提高了其对Hg0的脱除能力,并且随铁氧化物含量升高,MAtp脱汞能力逐渐增强;在实验温度区间内,脱汞能力随温度的升高逐渐增强,MAtp对Hg0以化学吸附为主;O2、NO的添加有利于Hg0的脱除,但Hg0穿透率随浓度变化不显著;SO2抑制汞的脱除,并且随浓度的增加,其抑制效果更加明显,但是当NO和SO2共同存在时,NO能明显削弱SO2对脱汞的抑制作用.

A method was proposed to remove NOx and SO2 in flue gas by using the sulfinyl functional group as a catalyst. Ozone is introduced into the flue gas to oxidize NO. Soluble NO2 and SO2 reacted with ammonia to form ammonium sulfate and ammonium nitrate, which were the raw material of the compound fertilizer. A small pilot is built in a container that can be easily transported to power plant and extracts the actual flue gas directly from the gas duct. In order to obtain the best the SO2 and NOX removal efficiency in this experiment, many parameters were changed. Such as flue gas flow, ozone / NOX ratio, liquid-gas ratio, flue gas temperature, catalyst type, catalyst concentration, solution pH value. Results indicated that SO2 was cleaned up quite efficiently and the removal efficiency was nearly 99% under all conditions. the best NOX removal efficiency can reach 88%. The NOX removal efficiency depended primarily on ozone / NOX ratio, and the temperature of flue gas also had influence on the NOX removal efficiency. The optimum pH range is 5.6-6.3. After inspection by authoritative institutions, the quality of fertilizers is superior to national standards.

We present a new type of adjustable graphenebased attenuator, which is manufactured on a half-mode substrate integrated waveguide. The presented attenuator is constituted by a graphene sandwich structure spread on a halfmode substrate integrated waveguide. The attenuation of this attenuator can be adjusted by adjusting the square resistance of graphene. From 8 GHz to 19 GHz, the attenuation can be adjusted from 3 dB to 15 dB.

为了研究Ca(OH)2对Zn和Pb的固留作用,向将添加Ca(OH)2的工业污泥在管式炉内进行焚烧,通过原子吸收分光光度计对焚烧后残渣中的重金属元素进行测定和分析.结果表明,在无添加剂的情况下,随着温度的升高,污泥焚烧后残渣中的Zn和Pb的含量先减小,后增加,再减小;Ca(O H)2对重金属的固留作用有一定的选择性,Ca(O H)2对污泥焚烧过程中的Zn有一定的固留作用,在Ca(O H)2添加量为3％ 时,Ca(O H)2对Zn的固留作用最佳;但是Ca(O H)2在污泥焚烧过程中会促进Pb的挥发,随着Ca(OH)2添加量的增加,对促进Pb挥发的作用越来越明显.

Nowadays, membrane separation technology has been one of the most effective technologies for CO2 capture. The coexistent components in the actual flue gas, such as water vapor, SO2, O2 and fine particles, may have a significant influence on the separation performance of polymeric membranes for CO2 capture. In order to comprehensively and systematically investigate the effects of these components, a series of lab-scale separation experiments for CO2 capture were conducted in the simulation test-bed with the commercially available flat-sheet polysulfone (PSF) membranes. At first, the operation conditions were optimized for CO2 separation by PSF membranes and the best operation conditions were 0.4MPa as the feed gas pressure, 400L/h as the residual gas flow rate and 50°C as the feed gas temperature. Then, the PSF membrane performances on CO2 separation in the presence of water vapor, SO2, O2 and fine particles in the actual flue gas were studied. It was found that water vapor promotes the CO2 separation performance of PSF membranes by a net increase of the CO2/N2 selectivity, CO2 permeability and CO2 enrichment efficiency. O2 slightly inhibits the CO2 separation performance, while the effect of SO2 is negligible. The gypsum fine particles significantly deteriorate CO2 separation performance of PSF membranes, which mainly results from the occupation of the effective membrane area, the increase of the mass transfer resistance and the partial adsorption of the gases by the gypsum fine particles deposited on the membranes.

Aqueous ammonia is one of reagents absorbing CO2 and is of vast development potential. In this paper the reaction between decarbonization rich liquid and carbide slug is used for assisting CO2 storage and recycle of aqueous ammonia at normal temperature and pressure. Using aqueous NH4HCO3 as rich liquid, pH and conductivity change during carbonation process were measured, and XRD, SEM and TGA employed for analysis of carbonation reaction products. Meanwhile, compared with aqueous ammonia having same concentration, carbonation reaction solution was also used to absorb CO2. The results show that the carbonation reaction can be accomplished in short time, and the higher temperature and liquid-solid ratio are, the faster the reaction rate is. Besides, ultrasonics can make carbide slug particles smaller, and carbonation reaction solution can be recycled as its property is similar to aqueous ammonia of the same concentration.