Novel high-entropy oxides for energy storage and conversion:From fundamentals to practical applications

High-entropy oxides(HEOs)are gaining prominence in the field of electrochemistry due to their distinctive structural characteristics,which give rise to their advanced stable and modifiable functional properties.This review presents fundamental preparations,incidental characterizations,and typical structures of HEOs.The prospective applications of HEOs in various electrochemical aspects of electrocatalysis and energy conversion-storage are also summarized,including recent developments and the general trend of HEO structure design in the catalysis containing oxygen evolution reaction(OER)and oxygen reduction reaction(ORR),supercapacitors(SC),lithium-ion batteries(LIBs),solid oxide fuel cells(SOFCs),and so forth.Moreover,this review notes some apparent challenges and multiple opportunities for the use of HEOs in the wide field of energy to further guide the development of practical applications.The influence of entropy is significant,and high-entropy oxides are expected to drive the improvement of energy science and technology in the near future.

Configuring topologically optimum vapor recompressed dividing-wall distillation columns to maximize operating efficiency

For dividing-wall distillation columns(DWDCs) separating a heavy-component dominated and wide boiling-point ternary(HCDWBT) mixture, a significant amount of excessive heat exists inevitably in stripping the heavy-component from the intermediate-component and it can be employed to initiate the development of vapor recompression heat pump(VRHP) assisted DWDC(VRHP-DWDC). Despite dividing wall may locate in the top, middle, and bottom, the optimum VRHP-DWDC is found to involve uniformlytwo VRHP circles. While the first one serves to compress and transform the excessive heat resulted from the separation of the heavy-component from the intermediate-component, the second one to compress and transform the overhead vapor stream of the light-component pre-heated sequentially with the condensate from the first one and the bottom product stream of the heavy-component, both releasing the temperature-elevated latent heat to the pre-fractionator's or common stripping section. The processing of two HCDWBT mixtures of benzene/toluene/o-xylene and n-pentane/n-hexane/n-heptane are selected to assess the derived optimum topological configurations of the VRHP-DWDC and their optimality is confirmed through detailed comparisons with the DWDC and two VRHP-DWDCs involving only one VRHP circle. The proposed strategy helps to tap the full potential of the VRHP-DWDC with considerably alleviated complication in process development.

Reinforced temperature control of a reactive double dividing-wall distillation column

The mass and thermal coupling makes the control of the reactive double dividing-wall distillation column(R-DDWDC) an especially challenging issue with a highly interactive nature. With reference to the separation of an ideal endothermic quaternary reversible reaction with the most unfavorable ranking of relative volatilities(A + B ■ C + D with α_(A)>α_(C)>α_(D)>α_(B)), the operation rationality of the R-DDWDC is studied in this contribution. The four-point single temperature control system leads to great steady-state discrepancies in the compositions of products C and D and the reason stems essentially from the failure in keeping strictly the stoichiometric ratio between reactants A and B. A temperature plus temperature cascade control scheme is then employed to reinforce the stoichiometric ratio control and helps to secure a substantial abatement in the steady-state discrepancies. A temperature difference plus temperature cascade control scheme is finally synthesized and leads even to better performance than the most effective double temperature difference control scheme. These outcomes reveal not only the operation feasibility of the R-DDWDC but also the general significance of the proposed temperature difference plus temperature cascade control scheme to the inferential control of any other complicated distillation columns.

Temperature inferential control of a reactive distillation column with double reactive sections

Temperature inferential control (TIC) is studied for a reactive distillation column with double reactive sections (RDC-DRSs) processing a hypothetical two-stage consecutive reversible reaction (A + B■C + D, C + B■E + D with αD > αB > αC > αA > αE). Because of the complicated dynamic behaviors, the controlled stages by sensitivity analysis lead to great steady-state deviations (SSDs) in top and bottom product purities. Since TIC involves considerably reduced settling times in comparison with direct composition control, small SSDs in product qualities correspond generally to small transient deviations (TDs) in product qualities. An objective function that measures SSDs in product qualities is formulated to represent the performance of a TIC system and an iterative procedure is devised to search for the best control configuration. The application of the procedure to the RDC-DRS gives considerably suppressed TDs and SSDs in top and bottom product qualities as compared with the one by sensitivity analysis. The method is simpler in principle and less computationally intensive than the current practice. These striking outcomes show the effectiveness of the proposed principle for the development of TIC systems for complicated reactive distillation columns.

癌症患者维生素D营养状况分析

背景与目的维生素营养状况与癌症患者之间存在一定的关联,已有研究表明缺乏维生素会增加罹患癌症的风险,本研究的目的是了解癌症患者的维生素D营养状况,为进一步实施营养干预提供科学依据。方法本研究回顾性分析了2017年7月-2019年6月在山东省肿瘤医院就诊的癌症患者血清25-羟维生素D的水平,采用SPSS20.0统计软件进行单因素分析和多元线性回归分析。结果本研究共纳入2,487例癌症患者,平均血清25-羟维生素D的浓度为(12.70±6.82)ng/m L,纳入的癌症患者中维生素D缺乏者[25(OH)D<20.00 ng/m L]占比92.20%。单因素分析显示:年龄、身体质量指数(body mass index, BMI)和癌症类型(P<0.05)与维生素D缺乏显著相关。进一步的多因素分析显示,BMI(β=0.71)、年龄(β=-0.56)、季节(与夏季相比,冬季β=-0.99;秋季β=-0.76)和癌症的种类(与其他类型的癌症相比,肺癌β=-1.17;食管-胃癌β=-1.45;结直肠癌β=-1.05)与25-羟维生素D水平显著相关(P<0.05)。结论癌症患者25-羟维生素D水平偏低,存在严重的维生素D缺乏状况,其可能与年龄、BMI、季节和癌症类型有关,这表明应该加强对癌症患者维生素D水平的监测。

Enhanced temperature difference control of distillation columns based on the averaged absolute variation magnitude

Temperature difference control(TDC)schemes can clearly suppress the adverse influence of pressure variations on product quality control of various distillation columns(DCs)by employing temperature differences(TDs)between the sensitive stage temperature(T_(S))and reference stage temperature(T_(R)),i.e.,T_(S)-T_(R),to infer the controlled product qualities.However,because the TDC scheme has failed to specially take the corresponding relationship between the TD employed in each control loop and the controlled product quality into account,it may suffer from relatively large steady-state errors in the controlled product qualities.To address this problem,an enhanced TDC(ETDC)scheme is proposed in the current article,in which an enhanced TD(ETD),i.e.,T_(S)-α×T_(R),is employed to replace the conventional TD for each control loop.While the locations of the sensitive and reference stages of the ETD are respectively determined according to sensitivity analysis and SVD analysis,the adjusted coefficientαis set to be the ratio between the averaged absolute variation magnitudes(AAVMs)of the T_(S)and T_(R)so that the relationship between the T_(S)and T_(R)can be appropriately coordinated.With reference to the operations of three different distillation systems,i.e.,one conventional DC distilling an ethanol(E)/butanol(B)binary mixture,one conventional DC distilling an E/propanol(P)/B ternary mixture,and one dividing-wall distillation column distilling an E/P/B ternary mixture,the performance of the ETDC scheme is assessed by compared with the conventional TDC scheme and the double TD control(DTDC)scheme.The dynamic simulation results show that the ETDC scheme is better than the conventional TDC scheme with reduced steady-state errors in the controlled product qualities and improved dynamic responses,and is comparable with the DTDC scheme despite the less temperature measurements are employed.

Vapor recompressed dividing-wall distillation columns:Structure and performance

Due to the topological structure of double columns and multiple separating sections in dividing-wall distillation columns(DWDCs),the development of vapor recompressed dividing-wall distillation columns(DWDC-VRHPs)represents a challenging issue with great complexities and tediousness.For the separations of light-component dominated and wide boiling-point ternary mixtures,because the purification of the light-component from the intermediate-and heavy-components incurs the primary energy dissipation,the application of vapor recompressed heat pumps(VRHP)should be aimed to reduce the irreversibility and this leads to the generation of the optimum topological structures of the DWDC-VRHPs,i.e.,a DWDC plus a two-stage VRHP.The first-stage VRHP is to preheat feed,not only taking the advantages of the small temperature elevation available but also favoring the mass transfer between the vapor and liquid phases through feed splitting.The second-stage VRHP is to reduce further separation irreversibility.The philosophy can be applied to any DWDCs no matter where the dividing wall locates.Two case studies on the separations of ternary mixtures of benzene,toluene,and o-xylene and n-pentane,n-hexane,and n-heptane demonstrate the economic optimality of the proposed DWDC-VRHPs and reveal the inherent interplay between internal and external process integration.

Unique influences of reboiler inventory control on the operation of totally reboiled reactive distillation columns

In this work,the dynamics and operation of the totally reboiled reactive distillation columns are visualized in terms of transfer function based process models.This kind of processes is found to be characterized by underdamped step responses due to the special topological configuration and the intricate interplay between the reaction operation and the separation operation involved.The under-dampness can be substantially alleviated through the tight inventory control of bottom reboiler and this presents beneficial effects to process dynamics and operation.Two totally reboiled reactive distillation columns,separating,respectively,a hypothetical synthesis reaction from reactants A and B to product C,and a real decomposition reaction from 1,4-butanediol to tetrahydrofuran and water,are employed to demonstrate these uncommon behaviors.The results obtained give full support to the above qualitative interpretation.Despite the strong influences of reaction kinetics and thermodynamic properties of the reacting mixtures,the totally reboiled reactive distillation columns are generally considered to present such unique behaviors and require tight inventory control of bottom reboiler to facilitate their control system development.

Interpreting the dynamic effect of internal heat integration on reactive distillation columns

In this work,the impact of internal heat integration upon process dynamics and controllability by superposing reactive section onto stripping section,relocating feed locations,and redistributing catalyst within the reactive section is explored based on a hypothetical ideal reactive distillation system containing an exothermic reaction:A + BC + D.Steady state operation analysis and closed-loop controllability evaluation are carried out by comparing the process designs with and without the consideration of internal heat integration.For superposing reactive section onto stripping section,favorable effect is aroused due to its low sensitivities to the changes in operating condition.For ascending the lower feed stage,somewhat detrimental effect occurs because of the accompanied adverse internal heat integration and strong sensitivity to the changes in operating condition.For descending the upper feed stage,serious detrimental effect happens because of the introduced adverse internal heat integration and strong sensitivity to the changes in operating condition.For redistributing catalyst in the reactive section,fairly small negative influence is aroused by the sensitivity to the changes in operating condition.When reinforcing internal heat integration with a combinatorial use of these three strategies,the decent of the upper feed stage should be avoided in process development.Although the conclusions are derived based on the hypothetical ideal reactive distillation column studied,they are considered to be of general significance to the design and operation of other reactive distillation columns.

Elevating the flexibility and operability of dividing-wall distillation columns via feed thermal condition adjustment

Because of the complicated interplay between the prefractionator and main distillation column involved,the black-hole problem might occur and prohibit the assignment of four specifications to dividing-wall distillation columns(DWDCs)(e.g., the three main product compositions plus an impurity ratio in the intermediate product), which lowers terribly process flexibility and operability. In this paper, a feed thermal condition adjustment strategy, achieved by the installation of a pre-heater in feed pipeline, is employed to eliminate the black-hole problem and serve to enhance process flexibility and operability. Through the strong influence to the overall mass and energy balance of the DWDC, the feed thermal condition adjustment can alter the interlinking flows between the thermally coupled prefractionator and main distillation column and work effectively to coordinate their relationship. A DWDC separating a benzene, toluene, and o-xylene mixture is chosen to ascertain the feasibility of the philosophy proposed. The static and dynamic studies demonstrate that the feed thermal condition adjustment is an effective way to refine process design and can completely eliminate the black-hole problem and elevate consequently process flexibility and operability.

Spatial heterogeneity of available zinc, copper, and manganese in Xiangcheng Tobacco Planting Fields, Henan Province, China

Geostatistical methods were used in combina-tion with geographical information system(GIS)technol-ogy to analyze the spatial distribution characteristics of available zinc,copper,and manganese in the Xiangcheng tobacco planting fields,Henan province,China.Analysis of the isotropic variogram indicated that the Zn semivar-iogram was well described with the Gaussian model,with the distance of spatial dependence being 900.7m;while the Mn semivariogram was well described with spherical models,with the distance of spatial dependence being 14060m;and,the Cu semivariogram was well described with exponential models,with the distance of spatial dependence being 27860.7m.Mn and Zn were strongly spatially dependent,with the C_(0)/sill being 0.014 and 0.147 in this given region;while Cu was moderately spatially dependent,with the C_(0)/sill being 0.3528.With the kriging analysis,the spatial distribution maps of contents of these three trace elements in the Xiangcheng tobacco planting regions was drawn with the Arcview software.It was found that the soils with higher content of Mn were mainly distributed in the high mountains of the southern part of the given regions,while the soils with higher content of Cu were mainly distributed in the south,decreasing from the south to the north.The soil with contents of Zn in the range of 0.76–1.33 mg/kg existed in the high mountains of the west and middle parts of the investigated regions,accounting for 76.11%of the whole area.

Mixed convective heat transfer characteristics and mechanisms in structured packed beds

The structured packed bed is considered a promising reactor owing to its low pressure drop and good heat transfer performance.In the heat transfer process of thermal storage in packed beds,natural convection plays an important role.To obtain the mixed convective heat transfer characteristics and mechanisms in packed beds,numerical simulations and coupling analyses were carried out in this study on the unsteady process of fluid flow and heat transfer.A three-dimensional model of the flow channel in the packed bed was established,and the Navier–Stokes equations and Laminar model were adopted for the computations.The effects of the driving force on fluid flow around a particle were studied in detail.The differences in velocity and density distributions under different flow directions due to effect of the aiding flow or opposing flow were intuitively demonstrated and quantitatively analyzed.It was found that the driving force strengthens the fluid flow near the particle surface when aiding flow occurs and inhibits the fluid flow when opposing flow occurs.The boundary layer structure was changed by the natural convection,which in turn influences the field synergy angle.For the aiding flow,the coordination between the velocity and density fields is higher than that for the opposing flow.By analysis the effects of physical parameters on mixed convective heat transfer,it is indicated that with an increase in the fluid-solid temperature difference or the particle diameter,or a decrease in the fluid temperature,the strengthening or inhibiting effect of natural convection on the heat transfer became more significant.

Advancements in compressed air engine technology and power system integration: A comprehensive review

The compressed air power system demonstrates the ability to convert the internal energy stored within com-pressed air into mechanical energy,thus facilitating power output.Its application within specific domains,such as special purpose vehicles,standby power sources,and fire and explosion prevention,holds significant research and practical value owing to its combustion-free operation,zero pollution and emissions.This paper aims to explain the operational principles and unique features of the compressed air engine(CAE).The reasons for selecting volume-type expanders as CAE components are detailed,including an analysis of their technical characteristics and research developments.Building on this foundation,the paper explores the operational characteristics and research status of traditional compressed air power systems installed in vehicles,with a particular focus on their limited range and excessive cold temperature.Furthermore,the study presents a comprehensive summary of the research progress made in the last few years relating to hybrid power systems that derive from conventional compressed air power systems.Finally,the paper concludes by outlining the expected development trajectory of CAEs and compressed air power systems.

玉米芯炭质燃料的理化性能及热解过程分析

研究了农业生物质废弃物玉米芯热解产物炭质燃料的理化性能与裂解温度的关系及热解机理,用FT-IR,XRD,SEM对玉米芯炭进行表征,分析了化学组成、官能团分布、芳构化程度与温度的关系.结果表明,随热解温度升高,热解所得焦炭中固定碳和灰分增加,挥发分和水分减小,产率下降,热值先增加后减少,羰基和脂肪族官能团逐渐被破坏,结晶度和芳构化程度不断增强.500℃时,焦炭热值大于32 MJ/kg,产率大于24%,固定碳大于80%,灰分小于4%,且具有发达的孔洞结构,各项指标接近或优于市售燃料炭;233~533℃下玉米芯挥发最剧烈,具有1.5级反应的特征;热解温度从233~353℃上升至353~533℃时,表观活化能从68.15 k J/mol降至37.25 k J/mol.

Predicting thermal conductivity of liquid suspensions of nanoparticles (nanofluids) based on rheology

A methodology is proposed for predicting the effective thermal conductivity of dilute suspensions of nanoparticles （nanofluids） based on rheology. The methodology uses the rheological data to infer microstructures of nanoparticles quantitatively, which is then incorporated into the conventional Hamilton-Crosser equation to predict the effective thermal conductivity of nanofluids. The methodology is experimentally validated using four types of nanofluids made of titania nanoparticles and titanate nanotubes dispersed in water and ethylene glycol. And the modified Hamilton-Zrosser equation successfully predicted the effective thermal conductivity of the nanofluids.

Influence of Tip Clearance on Performance of a Contra-Rotating Fan

Influences of tip clearance on the tip flow and associated loss mechanism in a contra-rotating axial flow fan hasbeen studied in the paper, based on three dimensional numerical results. The results with different tip clearanceare compared in terms of stage efficiency, relative total pressure loss coefficient, flow angle. It is found that theefficiency of the contra-rotating fan changes almost linearly with increment of the tip clearance, however, efficiencyof the rear rotor is observed to decrease more dramatically than that of the forward rotor given same tipclearance variation. The analysis on the flow structure indicates that the tip region flow field is qualitatively similarin both rotors. However, with the same clearance value, the leakage flow in the rear rotor is effected by a tipleakage vortex of greater intensity caused by relative loading levels and the inter rotor interaction.

Study on Forced Convective Heat Transfer of Non-Newtonian Nanofluids

This paper is concerned with the forced convective heat transfer of dilute liquid suspensions of nanoparticles(nanofluids) flowing through a straight pipe under laminar conditions. Stable nanofluids are formulated by usingthe high shear mixing and ultrasonication methods. They are then characterised for their size, surface charge,thermal and theological properties and tested for their convective heat transfer behaviour. Mathematical modellingis performed to simulate the convective heat transfer of nanofluids using a single phase flow model and consideringnanofluids as both Newtonian and non-Newtonian fluid. Both experiments and mathematical modellingshow that nanofluids can substantially enhance the convective heat transfer. Analyses of the results suggest thatthe non-Newtonian character of nanofluids influences the overall enhancement, especially for nanofluids with anobvious non-Newtonian character.

Experimental investigation on the distribution uniformity and pressure drop of perforated plate distributors for the innovative spray-type packed bed thermal storage

As an innovative thermal energy technology,the spray-type packed bed has advantages of high efficiency and low cost.A liquid distributor is the key component for the spray-type packed bed for scattering heat-transfer liquid drops evenly.In this study,the distribution performance and pressure drop of the perforated plate distributors of different orifice diameters were studied experimentally.The experimental results indicate that orifice diameter has a greater effect on the distribution performance compared to flow rate.With an increase in flow rate,the flow pattern through the distributor changes from the uncovered drop to the covered drop and then to the jet flow.The covered drop pattern shows the best performance with a good distribution and a small pressure drop simultaneously,which is the design and optimization principle of the distributor for a spray-type packed bed.

Thermally drawn multifunctional fibers: Toward the next generation of information technology

As the fundamental building block of optical fiber communication technology,thermally drawn optical fibers have fueled the development and prosperity of modern information society.However,the conventional step-index configured silica optical fibers have scarcely altered since their invention.In recent years,thermally drawn multifunctional fibers have emerged as a new yet promising route to enable unprecedented development in information technology.By adopting the well-developed preform-to-fiber manufacturing technique,a broad range of functional materials can be seamlessly integrated into a single fiber on a kilometer length scale to deliver sophisticated functions.Functions such as photodetection,imaging,acoustoelectric detection,chemical sensing,tactile sensing,biological probing,energy harvesting and storage,data storage,program operation,and information processing on fiber devices.In addition to the original light-guiding function,these flexible fibers can be woven into fab-rics to achieve large-scale personal health monitoring and interpersonal com-munication.Thermally drawn multifunctional fibers have opened up a new stage for the next generation of information technology.This review article summarizes an overview of the basic concepts,fabrication processes,and developments of multifunctional fibers.It also highlights the significant pro-gress and future development in information applications.

Evaluation of tobacco soil fertility suitability of the Sanmenxia area, China, based on geographic information systems

The growth of flue-cured tobacco is sensitive to changes in environmental conditions.Excellent tobacco leaf production is strictly restricted by regional cultivated lands.For the purpose of reasonable utilization and scientific management of Sanmenxia tobacco fields,it is meaningful to evaluate the soil fertility suitability of tobacco crops quantitatively and objectively.In this study,the global positioning system(GPS)technology was used to obtain sample point information automatically.Based on the analysis of fertility properties of soil samples collected from the Sanmenxia tobacco planting regions in Henan Province,we present the index system of soil fertility suitability for tobacco crops.The integrated evaluation of soil fertility suitability was studied with six indices,including organic matter,pH value,available nitrogen(N),available phosphorus(P),available potassium(K),and chlorine(Cl–1)content of surface soil.The subjective grade value was calculated according to S-type and parabola-type functions of the effect of evaluation factors on tobacco crops.Further,the weight value of soil fertility suitability indices was calculated by the method of Hiberarchy analysis.The soil fertility suitability level was evaluated and classified.The suitability map of the Sanmenxia tobacco planting regions in Henan Province was then drawn with the geographic information system(GIS)software mapGIS.It was found that highly suitable fields were mainly distributed in the high mountains in the Southwestern part of the investigated regions where soil pH value and the contents of organic matter were medium,but the contents of available P and available K were higher,accounting for 79.36% of the whole area.Suitable fields were 17% of the whole area,mainly distributed in the middle part of the investigated regions where soil pH value was higher.Unsuitable fields existed in the northern-east and middle part of the Sanmenxia where the contents of soil Cl^(–)was very high,accounting for 3.51%of the whole regions.