Conversion Characteristics Research Articles

Crude oil removal by Meyerozyma consortium and nitrogen supplement: Hydrocarbon transformation, nitrogen fate, and enhancement mechanism

Hydrocarbon removal and nitrogen conversion characteristics mediated by nitrogen sources and microorganisms in aqueous environments are not well understood. In this study, two forms of nitrogen sources, NH4+-N and NO3--N, and the Meyerozyma consortium were selected to degrade petroleum hydrocarbons. The combination of NO3--N and the Meyerozyma consortium showed a higher removal rate of total petroleum hydrocarbons (TPH) (84.25 %), saturates (64.25 %), and aromatics (32.86 %) than the combination of NH4+-N and the Meyerozyma consortium (56.14 %, 64.32 %, and 29.47 %, respectively), which was attributed to the enhanced availability of NO3--N for synthesis as biomass N by the Meyerozyma consortium. Nitrogen sources and the Meyerozyma consortium stimulated the activity of Stenotrophomonas in crude oil, with a relative abundance of 92.1 %. Hydrocarbon transformation and nitrogen balance analysis indicated that 80.81 % of the TPH were biodegraded by the Meyerozyma consortium and Stenotrophomonas, and 42.0 % of nitrogen was converted into gaseous nitrogenous products via denitrification. The Meyerozyma consortium and Stenotrophomonas were key microorganisms driving hydrocarbon degradation and nitrogen cycling, which enhanced nitrogen assimilation and denitrification, respectively.

4th Order LC-Based Sigma Delta Modulators.

Due to the characteristic of narrow band conversion around a central radio frequency, the Sigma Delta Modulator (ΣΔM) based on LC resonators is a suitable option for use in Software-Defined Radio (SDR). However, some aspects of the topologies described in the state-of-the-art, such as noise and nonlinear sources, affect the performance of ΣΔM. This paper presents the design methodology of three high-order LC-Based single-block Sigma Delta Modulators. The method is based on the equivalence between continuous time and discrete time loop gain using a Finite Impulse Response Digital-to-Analog Converter (FIRDAC) through a numerical approach to defining the coefficients. The continuous bandpass LC ΣΔM simulations are performed at a center frequency of 432 MHz and a sampling frequency of 1.72 GHz. To the proposed modulators a maximum Signal-to-Noise Ratio (SNR) of 51.39 dB, 48.48 dB, and 46.50 dB in a 4 MHz bandwidth was achieved to respectively 4th Order Gm-LC ΣΔM, 4th Order Magnetically Coupled ΣΔM and 4th Order Capacitively Coupled ΣΔM.

Effects of Ca-Compounds on the Gases Formation Behavior during Molten Salts Thermal Treatment of Bio-Waste

Bio-waste utilization is essential, and pyrolysis is a prominent way for its effective utilization. However, the gradual accumulation of ash compounds in the intermediate products probably affects the thermal conversion characteristics of bio-waste. In the present study, beech wood and disposable chopsticks were selected as bio-waste samples. The effects of typical ash components (Ca-compounds) on volatile formation behavior were investigated during the molten salts thermal treatment of bio-waste. Results demonstrated that about 80% mass of initial bio-waste was gasified into the volatiles at 300 °C. The introduction of Ca-compounds in the molten salts slightly decreased the total yield of gaseous products. More specifically, Ca2+ could improve the generation of CO2 and suppress the generation of other gases (CO, H2, and CH4), and this is accompanied by a reduction in the low heating value (LHV) of the gases. The possible reason is that Ca2+ might act on the -OH bonds, phenyl C-C bond, methoxy bond and carboxylic acid -COOH bonds of the bio-waste to promote CO2 release. In contrast, the introduction of CO32− and OH- tended to relieve the inhibition effect of Ca2+ on the generation of H-containing gases. Meanwhile, the introduction of Ca2+ can promote the conversion of bio-waste into liquid products as well as increase the saturation level of liquid products. Moreover, as a vital form of carbon storage, CO2 was found to be abundant in the pyrolysis gases from molten salts thermal treatment of bio-waste, and the concentration of CO2 was much higher than that of direct-combustion or co-combustion with coal. It’s a promising way for bio-waste energy conversion as well as synchronized CO2 capture by using molten salts thermal treatment, while the introduction of small amounts of Ca-compounds was found to have no significant effect on the change of CO2 concentration.

MonkeyPox2022Tweets: A Large-Scale Twitter Dataset on the 2022 Monkeypox Outbreak, Findings from Analysis of Tweets, and Open Research Questions.

The mining of Tweets to develop datasets on recent issues, global challenges, pandemics, virus outbreaks, emerging technologies, and trending matters has been of significant interest to the scientific community in the recent past, as such datasets serve as a rich data resource for the investigation of different research questions. Furthermore, the virus outbreaks of the past, such as COVID-19, Ebola, Zika virus, and flu, just to name a few, were associated with various works related to the analysis of the multimodal components of Tweets to infer the different characteristics of conversations on Twitter related to these respective outbreaks. The ongoing outbreak of the monkeypox virus, declared a Global Public Health Emergency (GPHE) by the World Health Organization (WHO), has resulted in a surge of conversations about this outbreak on Twitter, which is resulting in the generation of tremendous amounts of Big Data. There has been no prior work in this field thus far that has focused on mining such conversations to develop a Twitter dataset. Furthermore, no prior work has focused on performing a comprehensive analysis of Tweets about this ongoing outbreak. To address these challenges, this work makes three scientific contributions to this field. First, it presents an open-access dataset of 556,427 Tweets about monkeypox that have been posted on Twitter since the first detected case of this outbreak. A comparative study is also presented that compares this dataset with 36 prior works in this field that focused on the development of Twitter datasets to further uphold the novelty, relevance, and usefulness of this dataset. Second, the paper reports the results of a comprehensive analysis of the Tweets of this dataset. This analysis presents several novel findings; for instance, out of all the 34 languages supported by Twitter, English has been the most used language to post Tweets about monkeypox, about 40,000 Tweets related to monkeypox were posted on the day WHO declared monkeypox as a GPHE, a total of 5470 distinct hashtags have been used on Twitter about this outbreak out of which #monkeypox is the most used hashtag, and Twitter for iPhone has been the leading source of Tweets about the outbreak. The sentiment analysis of the Tweets was also performed, and the results show that despite a lot of discussions, debate, opinions, information, and misinformation, on Twitter on various topics in this regard, such as monkeypox and the LGBTQI+ community, monkeypox and COVID-19, vaccines for monkeypox, etc., "neutral" sentiment was present in most of the Tweets. It was followed by "negative" and "positive" sentiments, respectively. Finally, to support research and development in this field, the paper presents a list of 50 open research questions related to the outbreak in the areas of Big Data, Data Mining, Natural Language Processing, and Machine Learning that may be investigated based on this dataset.

An ultrawideband stacked metasurface with collaborative polarization conversion and absorption characteristic for application of radar cross section reduction

In this paper, an ultrawideband metasurface with collaborative polarization conversion (PC) and absorption characteristic has been designed and applied into radar cross section (RCS) reduction. The unit cell of the proposed metasurface is a stacked structure composed of top-layer low-frequency PC-absorption (PCA) unit cell, the bottom-layer high-frequency PC unit cell, and metallic ground. Some lumped resistors are used in the low-frequency PCA unit cell to simultaneously improve the high-frequency transmission and low-frequency PCA performance. With orthogonal layout of two kinds of the unit cells, the parasitic Fano resonance can be avoided, and meanwhile the two operating bands are cascaded together to achieve an ultra-wide band with a frequency-ratio (FR) of 7.26 from 2.7 GHz to 19.6 GHz. The proposed metasurface is arranged into an array in a checkerboard way to obtain a low-RCS performance. The simulated and measured results are given to demonstrate a 10 dB RCS reduction in an ultrawideband of 2.85–18.65 GHz with a fractional bandwidth (FBW) of 146.98%.

Peroxidase-mimicking TA-VOx nanobranches for enhanced photothermal/chemodynamic therapy of glioma by inhibiting the expression of HSP60

Glioblastoma multiforme (GBM) is the most prevalent malignant brain tumor. It expresses high levels of heat shock protein (HSP60), which is associated with poor prognosis. Chemodynamic therapy (CDT) can be improved by photothermal therapy (PTT) and facilitate tumor eradication. Therefore, it is necessary to develop novel agents that synergize with the tumor killing effects of PTT/CDT by downregulating HSP60. Based on The Cancer Genome Atlas (TCGA) and Chinese Glioma Genome Atlas (CGGA) databases and clinical cases, this study determined that HSP60 was upregulated and associated with reduced overall survival (OS) in GBM patients. Herein, TA-VOx nanobranches (TA-VOx NBs) were successfully synthesized by a one-step self-assembly procedure, which had excellent photothermal conversion characteristics and improved peroxidase-mimicking activity at elevated temperatures. Moreover, TA-VOx NBs can degrade to VO2+ in a slightly acidic tumor microenvironment. In vitro and in vivo studies showed that TA-VOx NBs synergized with PTT/CDT and improved glioma eradication under 808 nm irradiation due to the heat-induced ROS generation and the inhibition of HSP60. Furthermore, TA-VOx NBs were rapidly cleared by the kidney and showed good biosafety. Combined with the ease of fabrication, this is a promising nanomaterial that can be introduced for clinical translation in cancer therapy.

Study on energy conversion characteristics and pressure fluctuation interference characteristics between two stage impellers of the pump as turbine

The process pump as turbine (PPAT) is an important infrastructure in chemical and oil refining process. When it operates in pump mode, it can provide high-pressure energy for chemical and oil refining system, and when it operates in turbine mode, it can recover the high-pressure energy from the oil medium. The operation stability of PPAT directly affects the normal operation and production of chemical and oil refining process. In this paper, the velocity slip characteristics of the PPAT in turbine mode and pump mode were studied, and the unsteady operation characteristics and the energy conversion and distribution mechanism of the first-stage impeller and second-stage impeller in pump mode were mainly studied, the pulsation amplitude frequency characteristics and induction mechanism of flow passage components under different flow conditions in pump mode are analyzed. The results show that PPAT has an efficiency peak in both pump mode and turbine mode, and the efficiency zone is significantly wider and the velocity slip loss is smaller in turbine mode; In turbine mode, with the increase of flow, the velocity slip loss of the first-stage impeller is larger than that of the second-stage impeller; In the pump mode, the velocity slip loss of the first-stage impeller is greater under the conditions of minimum flow and maximum flow, the pressure fluctuation in the PPAT is mainly distributed in the first stage diffuser and the second stage diffuser. The main factor causing the pressure fluctuation in the PPAT is the dynamic and static interference effect between the first-stage impeller and the first-stage diffuser.

Counterattacking long videos: exploring the characteristics of popular instant videos and roles of producers and viewers

PurposeRecently, analyses of the characteristics of viral content in the social media field have attracted considerable attention. However, the influence of instant videos has grown significantly, and most social media platforms have begun to introduce them.Design/methodology/approachThe authors conducted a series of independent-samples t-tests using a large-scale data set collected from the YouTube Shorts platform to identify the characteristics of popular instant videos and discussions surrounding them. The authors further analyzed how they differ from other viral content.FindingsThe results indicate that viewers leave varied variety of comments based on the topic of conversation in the community, rather than on the video itself. Furthermore, video producers and viewers attempt to reach a consensus in a straightforward and intuitive manner. All analyzed texts contained appropriate attitudes and tendencies according to their roles on the platform.Originality/valueThis study aimed to discover and understand the video and conversational characteristics of popular instant videos, which differ from the existing widely known viral content.

Utilization of light energy and photodynamic therapy based on thylakoid membranes

<p indent="0mm">The thylakoid membrane, which contains photosynthetic pigments, lipids and proteins, is the main site where the photosynthetic light reaction of green plants, eukaryotic algae and cyanobacteria occurs. Water photolysis and photosynthetic electron transport are two core processes of the light reaction. The former is responsible for converting photons into electrons, and the latter then condenses the energy from the high-potential electrons into energy carriers such as adenosine triphosphate (ATP) and reduced nicotinamide adenine dinucleotide phosphate (NADPH). Due to the electron transport and energy conversion properties of the light reaction, thylakoid membrane can be used in biophotoelectrochemical and biophotoelectrocatalytic systems. Biophotoelectrochemical systems refer to direct or indirect extraction of electrons from the photosynthetic electron transfer chain (PETC) of the thylakoid membrane and transfer the electrons into an external electrode, eventually converting light energy into electric current. Biophotoelectrocatalytic systems refer to the use of ATP and NADPH generated in the light reaction of the thylakoid membrane to drive a series of ATP- or NADPH-dependent biocatalytic reactions. These thylakoid membrane-based light energy utilization systems are featured with material renewability and environmental compatibility. In addition, they show higher energy efficiency than that of the whole photosynthetic-cell systems. Furthermore, thylakoid membranes also hold clear advantages over sub-cellular photosystems, including retention of photosynthetic complexes in their natural environment and relatively simple and fast procedures for their extraction and purification. For biophotoelectrochemical systems, scientists have optimized the electron transfer between the thylakoid membrane and electrode, for example by developing different immobilization methods, or modifying electrode surface with redox polymers and nanomaterials. As an effective platform for cofactor regeneration, the thylakoid membrane-based biophotoelectrocatalytic systems have been used to drive the enzymatic synthesis of poly(3-hydroxybutyrate) (PHB) from acetate, as well as CO₂ fixation through a synthetic crotonyl-coenzyme A (CoA)/ethylmalonyl-CoA/hydroxybutyryl-CoA (CETCH) cycle. In addition to light energy utilization, thylakoid membranes can also be used in photodynamic therapy (PDT) of tumors. Firstly, the photosensitizer porphyrin in the chlorophyll molecules can produce singlet oxygen (¹O₂) from O₂ under visible light irradiation, which in turn kills the tumor cells. Secondly, the photosynthetic oxygen evolution of thylakoid membrane can rapidly supply O₂ <italic>in situ</italic>. Moreover, thylakoid membranes contain abundant catalase, which catalyzes the decomposition of H₂O₂ into O₂, thus further increasing the supply of O₂. This paper summarizes recent progress in the research of thylakoid membranes in these three fields, focusing on the application forms and underlying mechanisms. Moreover, the difficulties and challenges in the application of thylakoid membrane are discussed, and future research directions are prospected. Specifically, developing protective structures such as hydrogels or artificial vesicles to address the issue of short half-life of isolated thylakoid membranes will be crucial. In light of their ingenious energy conversion characteristics and amenability for potential commercialization, thylakoid membrane-based biotechnological systems will have a bright future in the fields of bioenergy, biocatalysis and biomedicine.

Conversion of Glucose and Xylose to 5-Hydroxymethyl furfural, Furfural, and Levulinic Acid Using Ethanol Organosolv Pretreatment under Various Conditions

The objective of this study was to understand the conversion characteristics of glucose and xylose using the major monosaccharide standards for lignocellulosic biomass. The acid-catalyzed organosolv pretreatment conducted using ethanol was significantly different from the acid-catalyzed process conducted in an aqueous medium. 5-hydroxymethylfurfural (5-HMF), levulinic acid and furfural were produced from glucose conversion. The maximum yield of 5-HMF was 5.5%, at 200°C, when 0.5% sulfuric acid was used. The maximum yield of levulinic acid was 21.5%, at 220°C, when 1.0% sulfuric acid was used. Furfural was produced from xylose conversion and under 0.5% sulfuric acid, furfural reached the maximum yield 48.5% at 210°C. Ethyl levulinate and methyl levulinate were also formed from the glucose standard following the esterification reaction conducted under conditions of the combined conversion method, which proceeded under both ethanol-rich and water-rich conditions.

Characterization of Tensile Crack Propagation and Energy Evolution during the Failure of Coal–Rock Samples Containing Holes

The instability and fracturing of gas drainage boreholes are one of the main causes of low drainage efficiency. Based on the rock mass energy principle and the Barenblatt model, the energy evolution of the coal–rock mass around the hole, the conversion characteristics of the dissipated energy Ud, and the propagation pattern of the initial tensile cracks were investigated. The results show that based on the conversion process of the dissipated energy, the failure process of samples containing holes can be divided into an initial dissipation stage, a decelerated dissipation stage, a stable dissipation stage, and an accelerated dissipation stage. The dissipated energy is always greater than the elastic energy during the first half of loading, and it is mainly used for the continuous development and propagation of initial tensile cracks. Then, remote cracks and cracks to the left and right of the hole boundary are generated to inhibit the propagation of the tensile cracks. Later, when the energy storage limit is reached, the elastic strain energy around the hole is released, and the macroscopic failure cracks propagate and coalesce, which causes the stress environment to change and the tensile cracks to reopen and finally propagate. The tensile cracks in the upper and lower ends of the holes undergo an opening–closing–reopening process, and the presence of cohesion c(x) hinders the propagation of the tensile cracks that are formed by the generation and migration of fracture initiation zone, friction zone, and intact zone. The dissipated energy released was related to the different stages of the tensile crack propagation, which could be used for the structure monitoring and flaw predicting of the gas drainage borehole.

Photothermal conversion characteristics and exergy analysis of TiN@h-BN composite nanofluids

Photothermal conversion characteristics and exergy analysis of TiN@h-BN composite nanofluids

국내 의료중국어 회화교재의 대화문 분석 및 개선 방안

Objectives This study investigates medical conversations in Chinese between doctors and patients in medical Chinese textbooks compiled in Korea from the conversation analytic perspective. Methods This study incorporates a conversation-analytic approach into the design of medical Chinese textbooks. Results The results indicate that medical Chinese textbooks do not properly present information on the conversation structures, rules, and characteristics essential to construct interactive conversations. Conclusions This study suggests that exposing learners to actual conversations is the most effective way to draw attention to the detail in real-life talk-in-interactions. By using authentic spoken language, learners can learn and practice interactional details, including turn-taking, sequences, linguistic features etc. Furthermore, it is important to apply conversation analytic research findings to enable learners to systematically understand, analyze, and communicate fluently in real medical conversations.

The quantitative study of interfacial contact effects in TEGs by real-topology-based simulations and novel indirect tests

The precise quantitative description of contact effects at heterogeneous interfaces is the crucial issue in developing thermoelectric generators (TEGs) with potential of hypersonic aerodynamic heat harvest. In this paper, the thermal and electrical contact effects between thermoelectric (TE) legs and electrodes are studied by real-topology-based numerical predictions and novel indirect experimental tests, and two simplified formulas are proposed to quantitatively express their effects on TEG. First, the thermal and electrical contact resistances under different temperatures, pressures, gap mediums and thermal radiation conditions are predicted. Second, a novel indirect thermal contact resistance (TCR) test approach relying on the TE conversion characteristics is developed, a corresponding platform is established and the numerical models are then validated. Third, the TE conversion process of TEG is simulated with considering the contact effects by equivalent layers, the TCR test platform is developed to measure the out power of TEG and the numerical models are then validated. Finally, two prediction formulas for the maximum output power prediction of TEGs with considering the contact effects are derived, and good agreement with numerical results is obtained by the maximum deviation of 7.7%.

Characteristics of Energy Conversion and Temperature Response of Coal Excited by a DC Electric Field.

This study is aimed at investigating the characteristics of energy conversion and temperature response of coal excited by a direct current (DC) electric field (CEEDCEF). First, factors influencing energy conversion and temperature response of CEEDCEF were theoretically analyzed. Based on the analysis, the temperature distribution law of coal under different excitation conditions was simulated using the COMSOL software. The results of theoretical analysis and numerical simulation were verified through an experiment on the temperature distribution on the surface of CEEDCEF. Finally, the energy conversion mechanism and temperature response characteristics of CEEDCEF were revealed. The research results show that loading time and the loading voltage are the main factors influencing the temperature rise of CEEDCEF. Under the excitation of 6000 V constant DC voltage, the internal temperature at the lower end face of CEEDCEF increased from 29.4 to 92 °C within 20-90 min, the sections of the internal temperature increased from 36 to 94 °C under different voltage excitations of 3000-6000 V. Moreover, the temperature rise response process is divided into three stages, i.e., slow warming, fast warming, and slow cooling into stabilization. The coal shows a "capacitance effect" in the early stage of DC electric field excitation and a "resistance effect" after the charge reaches saturation. In addition, the temperature surges when the free radicals in the macromolecular structure of the coal turn into a current beam. With the increase in excitation time, the electrical parameters of the coal tend to be stable, and the surface temperature slowly decreases and stabilizes accordingly. The research results provide theoretical support for the gas production mechanism of the coal stimulated by the electric field and exploring methods for the monitoring and prewarning of these dynamic disasters.

Numerical Modeling of Fixed-Bed Cocombustion Processes through the Multiple Thermally Thick Particle Model

Fixed-bed cocombustion provides opportunities for utilizing various low-quality solid residues, but there still remain obstacles for quantitative numerical modeling. The difficulties originate from the particles in the thermally thick regime and the diverse properties of different fuels. This work presents the multiple thermally thick particle (MTTP) model that considers detailed transport processes and chemical reactions in subparticle and interparticle scales, and different fuels can be assigned with distinctive physical and chemical properties. The model was validated by cocombustion experiments using wood and potato as representatives of low- and high-moisture fuels. The predicted results showed satisfactory agreement with measured values, and the characteristics of asynchronous conversion were clearly revealed. For thermally thick fuels with high moisture content, the drying process extends almost across the whole conversion zone and is highly overlapped with devolatilization process. Consequently, the structure of the in-bed conversion zone is beyond the expectation of conventional fixed-bed combustion theory.

Numerical analysis and experimental study on the thermoelectric characteristics of the Al–Si alloy used for building energy storage tile

This paper aims to explore the feasibility of the silicon aluminum (Al–Si) alloy for usage as a thermoelectric tile on building roofs. Through the simulation of the heat conduction characteristics and temperature field distribution of the step-shaped Al–Si alloy sample, the effects of the thickness, material, and shape of the Al–Si alloy sample on its thermal conversion efficiency and temperature field distribution characteristics of continuous solar irradiation were studied. The energy conversion characteristics of the Al–Si alloy sample combined with a thermoelectric generator (TEG) were investigated by numerical analysis and experiment. The results show that the Al–Si alloy sample with a thickness of 10 mm had a good heat storage efficiency. Also, the Al–Si alloy tile with a plane shaped solar irradiation surface and the back-sun surface with a certain number of bosses has a better heat transfer efficiency. Through experiment and calculation demonstrate that an Al–Si alloy tile with 500 mm × 500 mm area could generate 1.64 W electric power.

Characteristics of CO, CO2 generation and reactive group conversion in isothermal smoldering combustion of coal

The process of coal smoldering combustion will produce a significant number of CO and CO2 gases, causing environmental pollution and casualties. It is important to elucidate the law and mechanism of CO and CO2 generation during coal smoldering combustion. In this paper, the CO and CO2 production patterns and the relationship of reactive group conversion during isothermal smoldering combustion were investigated by TG-MS and FT-IR. Results reveal that the CO and CO2 generation curves with time during isothermal smoldering combustion of coal in the first stage conform to the polynomial function Y1=A1+B1t+C1t2+D1t3+E1t4, in the second stage accord with the complex exponential function Y2=A2+B2ekt (k < 0), as well as the CO + CO2 production curve. The consumption rate function of functional groups during isothermal smoldering combustion is calculated from the CO + CO2 production curve as v=L·YCO + CO21000000Vm. As the isothermal temperature rises, the rate of coal combustion in smoldering combustion accelerates, causing an exponential increase in CO + CO2 emissions and reactive group consumption. The CO and CO2 emissions vary considerably at different isothermal temperatures, which is due to the increase in the number and type of reactive groups involved in the reaction with rising temperature. During isothermal smoldering combustion of coal, in exception to the direct generation of CO and CO2 from carboxyl and carbonyl groups, aliphatic hydrocarbons are key groups for the continuous generation of CO and CO2, and are also important mediators for the formation of carboxyl and carbonyl groups. The hydroxyl group acts as a reactant at relatively low temperatures and plays an essential role in driving the reaction. The aromatic hydrocarbon is the principal source of CO and CO2 at higher temperatures. This study will help to forecast the degree of coal smoldering combustion and to control coal smoldering combustion.

A novel circularly polarized patch antenna based on polarization conversion metasurface for radiation and scattering performance improvement

A new design based on sequential-rotation arranged polarization conversion metasurfaces (PCMs) is proposed for reducing backscattering and improving radiation performance of circularly polarized (CP) patch antennas. The proposed antenna is composed of a conventional corner-truncated patch antenna loaded with a PCMs. The configuration of the PCMs increases the operating bandwidth and realized gain, as well as reduce radar cross section (RCS). The relative CP bandwidth (both |S11| < −10 dB and AR <3 dB) is improved to 13.65% due to achieving an additional mode by the PCMs. Also, the peak gain is enhanced by 6.6 dB. Moreover, an in-band and out-of-band RCS reduction is achieved compared with the conventional CP patch antenna due to the polarization conversion characteristic of the PCMs. The maximum RCS reduction is 27.5 dB within the band. This design enables an effective strategy for wideband, high-gain, and low-RCS CP patch antennas. A sample operating at C-band was fabricated and measured, demonstrating a satisfactory match between simulation and measurement results, so verifying the proposed idea.

The competition/inhibition effect of H2O/CO2-char gasification in typical in situ gasification-chemical looping combustion (iG-CLC) conditions via particle-resolved simulation

In the fuel reactor of in-situ gasification chemical looping combustion (iG-CLC), the solid fuel (e.g., coal, biomass) goes through two typical processes: devolatilization and char gasification. Then the pyrolysis and gasification products react with oxygen carrier to produce CO2 and H2O ideally. The slow char gasification rate during iG-CLC is responsible for combustion efficiency. Therefore, a deeper understanding of char conversion characteristics is required to optimize iG-CLC conditions. In this paper, a particle-resolved simulation with detailed heterogeneous reactions is conducted, in which the effects of char particle size and reaction temperature on char conversion characteristics are carefully studied. To understand the competition between CO2 gasification and H2O gasification, single-particle simulations are carried out under mixed and separate atmospheres. The char gasification rate in CO2/H2O mixtures (rmix) is lower than the sum of the char-H2O gasification rate (rH2O) and the char-CO2 gasification rate (rCO2). We find that the competition for active sites between char-H2O gasification and char-CO2 gasification is not significant, while the inhibition of gasification products play an important role in char-CO2 gasification, particularly the inhibition of CO (from char-H2O or char-CO2 gasification), due to the accumulation of H2 and CO inside the char particle. The inhibition effect is quantified via particle-resolved simulations and then a quantitative formula is attained to describe the complex relationship between H2O gasification and CO2 gasification. Then the point-source model for H2O/CO2-char gasification is developed for computational fluid dynamics simulations. Straightforward cloud diagrams are presented to explore the relationship between conversion rate characteristics and physicochemical properties of char, providing useful information for the optimization of iG-CLC conditions.