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A review on different theoretical models of electrocaloric effect for refrigeration

《能源前沿(英文)》 2023年 第17卷 第4期   页码 478-503 doi: 10.1007/s11708-023-0884-6

摘要: The performance parameters for characterizing the electrocaloric effect are isothermal entropy change and the adiabatic temperature change, respectively. This paper reviews the electrocaloric effect of ferroelectric materials based on different theoretical models. First, it provides four different calculation scales (the first-principle-based effective Hamiltonian, the Landau-Devonshire thermodynamic theory, phase-field simulation, and finite element analysis) to explain the basic theory of calculating the electrocaloric effect. Then, it comprehensively reviews the recent progress of these methods in regulating the electrocaloric effect and the generation mechanism of the electrocaloric effect. Finally, it summarizes and anticipates the exploration of more novel electrocaloric materials based on the framework constructed by the different computational methods.

关键词: electrocaloric effect     effective Hamiltonian     phase-field modeling     different theoretical models    

Analysis of effect of different construction methods of piles on the end effect on skin friction of piles

ZHOU Hongbo, CHEN Zhuchang

《结构与土木工程前沿(英文)》 2007年 第1卷 第4期   页码 458-463 doi: 10.1007/s11709-007-0062-7

摘要: Based on the comparative analysis of end effect on skin friction of displacement-pile (driven pile), the end effect on skin friction of bored pile is studied. The end effect on skin friction between driven pile and bored pile is different and the end effect on skin friction of bored pile is reduce of skin friction in the soil layer adjacent to the pile end. The degradation degree of skin friction is deduced with the increase of the distance from pile end. The concept of additional mud cake formed by the effect of cushion at the bottom of borehole during pouring concrete is introduced to explain the mechanism of end effect on skin friction of the bored pile. The test results of post-grouting piles indicate that the post-grouting technique is an effective way to improve the end effect on skin friction of bored pile.

关键词: distance     different     concept     additional     bottom    

Characterization and catalytic properties of mesoporous CuO/SBA-16 prepared by different impregnation

DONG Yongli, YUAN Fulong, ZHU Yujun, ZHAO Lina, CAI Zhicheng

《化学科学与工程前沿(英文)》 2008年 第2卷 第2期   页码 150-154 doi: 10.1007/s11705-008-0036-x

摘要: CuO/SBA-16 catalysts were prepared by two different routes – the conventional impregnation method and the modified impregnation method with pH adjustment. These catalysts were characterized by X-ray diffraction (XRD), atomic absorption spectrometry (AAS), N physisorption and hydrogen temperature programmed reduction (H-TPR) measurements which reveal that the cubic cage-like () pore structure of the parent SBA-16 molecule sieves was well maintained throughout the synthesis. After introduction of Cu, a different CuO dispersion exists on these catalysts. The CuO/SBA-16 prepared by modified impregnation method has a single highly dispersed CuO which is considered as a highly efficient species for hydroxylation of phenol with HO. CuO/SBA-16 prepared by the conventional impregnation method shows the presence of bulk CuO species which is undesirable for this reaction.

关键词: different     CuO/SBA-16     temperature     physisorption     introduction    

Effect of different high viscosity modifiers on rheological properties of high viscosity asphalt

《结构与土木工程前沿(英文)》 2021年 第15卷 第6期   页码 1390-1399 doi: 10.1007/s11709-021-0775-z

摘要: High viscosity asphalt (HVA) has been a great success as a drainage pavement material. However, the larger porosity of drainage asphalt mixtures weakens the cohesion and adhesion and leads to premature rutting, water damage, spalling and cracking. The purpose of this study was to investigate the rheological properties of HVA prepared using different high viscosity modifiers through conventional tests, Brookfield viscosity tests, dynamic shear rheometer tests and bending beam rheometer tests. The conventional performance results demonstrated SBS + rubber asphalt (SRA-1/2) exhibited excellent elastic recovery and low-temperature flexibility. The 60°C dynamic viscosity results indicated TPS + rubber asphalt (TRA) had the excellent adhesion. The rotational viscosity results and rheological results indicated that SRA-2 not only exhibited excellent temperature stability and workability, as well as excellent resistance to deformation and rutting resistance, but also exhibited excellent low-temperature cracking resistance and relaxation performance. Based on rheological results, the PG classification of HVA was 16% rubber + asphalt for PG76-22, 20% rubber + asphalt for PG88-22, TRA and SRA-1/2 for PG88-28. From comprehensive evaluation of the viscosity, temperature stability and sensitivity, as well as high/low temperature performance of HVA, SRA-2 was found to be more suited to the requirements of drainage asphalt pavement materials.

关键词: high viscosity asphalt     rheological properties     rubber     modifier     viscosity    

Enhanced performance of oxygen vacancies on CO adsorption and activation over different phases of ZrO

《能源前沿(英文)》 2023年 第17卷 第4期   页码 545-554 doi: 10.1007/s11708-023-0867-7

摘要: The effect of oxygen vacancies on the adsorption and activation of CO2 on the surface of different phases of ZrO2 is investigated by density functional theory (DFT) calculations. The calculations show that the oxygen vacancies contribute greatly to both the adsorption and activation of CO2. The adsorption energy of CO2 on the c-ZrO2, t-ZrO2 and, m-ZrO2 surfaces is enhanced to 5, 4, and 3 folds with the help of oxygen vacancies, respectively. Moreover, the energy barrier of CO2 dissociation on the defective surfaces of c-ZrO2, t-ZrO2, and m-ZrO2 is reduced to 1/2, 1/4, and 1/5 of the perfect surface with the assistance of oxygen vacancies. Furthermore, the activation of CO2 on the ZrO2 surface where oxygen vacancies are present, and changes from an endothermic reaction to an exothermic reaction. This finding demonstrates that the presence of oxygen vacancies promotes the activation of CO2 both kinetically and thermodynamically. These results could provide guidance for the high-efficient utilization of CO2 at an atomic scale.

关键词: CO2 activation     oxygen vacancies     ZrO2     different phases    

Untargeted metabolomic analysis of pregnant women exposure to perfluorooctanoic acid at different degrees

《环境科学与工程前沿(英文)》 2023年 第17卷 第3期 doi: 10.1007/s11783-023-1628-x

摘要:

● Metabolome can distinguish pregnant women exposure to PFOA at different degrees.

关键词: Perfluorooctanoic acid     Exposure     Pregnant women     Metabolomic     GSH     Microbiota metabolism    

Crystal modification of rifapentine using different solvents

Kun ZHOU, Jun LI, Jianhong LUO, Dongsheng ZHENG,

《化学科学与工程前沿(英文)》 2010年 第4卷 第1期   页码 65-69 doi: 10.1007/s11705-009-0302-6

摘要: Rifapentine crystals with different habits were prepared by recrystallization from selected solvents, such as methanol, ethanol, chloroform, and acetic acid. Scanning electron microscopy, X-ray powder diffractometry, infrared spectrometry, and differential scanning calorimetry were used to investigate the physicochemical characteristics of the prepared crystals. The comparative dissolution behaviors of the newly developed crystals and of rifapentine without being treated were also studied. Results show that the newly developed crystals were different from each other with respect to physical properties but were identical chemically. Needle-shaped crystals were obtained from methanol, ethanol, and chloroform solvents, and the block-shaped crystals were obtained from acetic acid solvent. X-ray diffraction spectra and differential scanning calorimetry investigation on those developed crystals clearly indicate that rifapentine has different crystal structure modification. When the crystal was obtained from acetic acid, the change of crystal habit was originated from the crystal structure modification. The dissolution rate of newly developed crystals was found to be higher than that of rifapentine without being treated. However, the modified crystal obtained from acetic acid shows the lower dissolution rate than crystals obtained from other solvents.

关键词: identical     scanning calorimetry     different     comparative dissolution     structure modification    

Multiple regression models for energy consumption of office buildings in different climates in China

Siyu ZHOU, Neng ZHU

《能源前沿(英文)》 2013年 第7卷 第1期   页码 103-110 doi: 10.1007/s11708-012-0220-z

摘要: The energy consumption of office buildings in China has been growing significantly in recent years. Obviously, there are significant relationships between building envelope and the energy consumption of office buildings. The 8 key building envelope influencing factors were found in this paper to evaluate their effects on the energy consumption of the air-conditioning system. The typical combinations of the key influencing factors were performed in Trnsy simulation. Then on the basis of the simulated results, the multiple regression models were developed respectively for the four climates of China—hot summer and warm winter, hot summer and cold winter, cold, and severely cold. According to the analysis of regression coefficients, the appropriate building envelope design schemes were discussed in different climates. At last, the regression model evaluations consisting of the simulation evaluations and the actual case evaluations were performed to verify the feasibility and accuracy of the regression models. The error rates are within±5% in the simulation evaluations and within±15% in the actual case evaluations. It is believed that the regression models developed in this paper can be used to estimate the energy consumption of office buildings in different climates when various building envelope designs are considered.

关键词: regression model     energy consumption     building envelope     office building     different climates    

Effectiveness of tertiary treatment processes in removing different classes of emerging contaminants

《环境科学与工程前沿(英文)》 2022年 第16卷 第11期 doi: 10.1007/s11783-022-1583-y

摘要:

● Different advanced treatment processes were tested for ECs removal from wastewater.

关键词: Micropollutants     Wastewater     PAC     Membranes     UV     Tertiary treatment    

Sulfonic acid-functionalized mesoporous silica catalyst with different morphology for biodiesel production

《化学科学与工程前沿(英文)》 2022年 第16卷 第8期   页码 1198-1210 doi: 10.1007/s11705-021-2133-z

摘要: Sulfonic acid functionalized mesoporous silica based solid acid catalysts with different morphology were designed and fabricated. The synthesized materials were characterized by various physicochemical and spectroscopic techniques like scanning electron microscope-energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller surface area, thermogravimetric analysis and n-butylamine acidity. The shape of catalysts particles plays an important role in its activity. The sulfonic acid functionalized mesoporous silica catalysts of spherical shape and the cube shape were assessed for catalytic activity in biodiesel production. The catalytic biodiesel production reaction over the catalysts were studied by esterification of free fatty acid, oleic acid with methanol. The effect of various reaction parameters such as catalyst concentration, acid/alcohol molar ratio, catalyst amount, reaction temperature and reaction time on catalytic activity were investigated to optimize the conditions for maximum conversion. It was sulfonated cubic shape mesoporous silica which exhibited better activity as compared to the spherical shape silica catalysts. Additionally, the catalyst was regenerated and reused up to three cycles without any significant loss in activity. The present catalysts exhibit superior performance in biodiesel production and it can be used for the several biodiesel feedstock’s that are rich in free fatty acids.

关键词: solid acid catalyst     mesoporous silica     sulfonic acid     biodiesel     esterification     oleic acid    

Aerodynamic performance of bowed compressor cascades with different camber angles

CHEN Shaowen, CHEN Fu, WANG Keli, GU Jun, WANG Zhongqi

《能源前沿(英文)》 2008年 第2卷 第3期   页码 306-312 doi: 10.1007/s11708-008-0056-8

摘要: The effects of a positively bowed blade on the aerodynamic performance of annular compressor cascades with different camber angles were experimentally investigated. The distributions of the exit total pressure loss and secondary flow vectors of the compressor cascades were analyzed. The static pressure was measured by tapping on the cascade surfaces, and the ink-trace flow visualizations were conducted. The results show that the value of the optimum bowed angle and optimum bowed height decrease because of the increased losses at the mid-span with the increase of the camber angle. The C-shape static pressure distribution along the radial direction exists on the suction surface of the straight cascade with larger camber angles. When bowed blade is applied, the larger bowed angle and larger bowed height will further enhance the accumulation of the low-energy fluid at the mid-span, thus causing the flow behavior to deteriorate. Under 60° camber angle, flow behavior near the end-wall region of some bowed cascades even deteriorates instead of improving because the blockage of the separated flow near the mid-span keeps the low-energy fluid near the end-walls from moving towards the mid-span region. As a result, a rapid augmentation of the total loss can easily take place under a large bowed angle.

关键词: increase     different     blockage     increased     ink-trace    

Removal efficiencies of natural and synthetic progesterones in hospital wastewater treated by different

《环境科学与工程前沿(英文)》 2022年 第16卷 第10期 doi: 10.1007/s11783-022-1558-z

摘要:

● The concentrations of 61 progesterones in HWW, PFTE, SBTE were evaluated.

关键词: Progesterones     Hospital wastewater     Primary filtration treatment effluent     Secondary biological treatment effluent     Disinfection process    

Dynamic performance of submerged floating tunnel with different mooring styles subjected to anchor cable

《结构与土木工程前沿(英文)》 2023年 第17卷 第10期   页码 1443-1464 doi: 10.1007/s11709-023-0932-7

摘要: Submerged floating tunnels (SFTs) are novel structures for transportation across long- and deep-strait regions. Owing to severe wave and current excitation as well as the effects of underwater structures and corrosion, the risk of local anchor cable failure is high, which can result in the progressive failure of the entire structure. In this study, experimental and numerical investigations are conducted to analyze the dynamic behavior of an SFT with different mooring styles under local cable failure. A custom-designed cable failure device and the birth-and-death element method are used to simulate cable failure (i.e., progressive failure) via experiments and numerical simulation, respectively. A physical-scale segmental model of an SFT with different mooring styles under anchor cable failure is developed in this study. A segmental and entire-length mathematical model is developed using the ANSYS program to perform the numerical simulation. The results of the segmental numerical and experimental models indicate good agreement. The dynamic response of an SFT with different mooring styles under cable failure is comprehensively investigated by investigating the effects of key parameters (wave period, buoyant weight ratio, and cable failure mechanism). Moreover, the progressive failure of the SFT under cable failure is investigated via a segment model test and a numerical simulation of its entire length. The present study can serve as a reference for the safer designs of the SFT mooring style.

关键词: dynamic behaviors     submerged floating tunnel     cable failure     mooring style     progressive failure    

Erratum to: Bending and vibration of a discontinuous beam with a curvic coupling under different axial

《机械工程前沿(英文)》 2022年 第17卷 第2期 doi: 10.1007/s11465-022-0709-z

Elastic modulus and thermal stress in coating during heat cycling with different substrate shapes

Daniel GAONA,Alfredo VALAREZO

《机械工程前沿(英文)》 2015年 第10卷 第3期   页码 294-300 doi: 10.1007/s11465-015-0351-0

摘要:

The elastic modulus of a deposit (Ed) can be obtained by monitoring the temperature (?T) and curvature (?k) of a one-side coated long plate, namely, a one-dimensional (1D) deformation model. The aim of this research is to design an experimental setup that proves whether a 1D deformation model can be scaled for complex geometries. The setup includes a laser displacement sensor mounted on a robotic arm capable of scanning a specimen surface and measuring its deformation. The reproducibility of the results is verified by comparing the present results with Stony Brook University Laboratory’s results. The ?k-?T slope error is less than 8%, and the Ed estimation error is close to 2%. These values reveal the repeatability of the experiments. Several samples fabricated with aluminum as the substrate and 100MXC nanowire (Fe and Cr alloy) as the deposit are analyzed and compared with those in finite element (FE) simulations. The linear elastic behavior of 1D (flat long plate) and 2D (squared plate) specimens during heating/cooling cycles is demonstrated by the high linearity of all ?k-?T curves (over 97%). The Ed values are approximately equal for 1D and 2D analyses, with a median of 96 GPa and standard deviation of 2 GPa. The correspondence between the experimental and simulated results for the 1D and 2D specimens reveals that deformation and thermal stress in coated specimens can be predicted regardless of specimen geometry through FE modeling and by using the experimental value of Ed. An example of a turbine-blade-shaped substrate is presented to validate the approach.

关键词: in-plane     Young’s modulus     curvature temperature     thermal stress     coating    

标题 作者 时间 类型 操作

A review on different theoretical models of electrocaloric effect for refrigeration

期刊论文

Analysis of effect of different construction methods of piles on the end effect on skin friction of piles

ZHOU Hongbo, CHEN Zhuchang

期刊论文

Characterization and catalytic properties of mesoporous CuO/SBA-16 prepared by different impregnation

DONG Yongli, YUAN Fulong, ZHU Yujun, ZHAO Lina, CAI Zhicheng

期刊论文

Effect of different high viscosity modifiers on rheological properties of high viscosity asphalt

期刊论文

Enhanced performance of oxygen vacancies on CO adsorption and activation over different phases of ZrO

期刊论文

Untargeted metabolomic analysis of pregnant women exposure to perfluorooctanoic acid at different degrees

期刊论文

Crystal modification of rifapentine using different solvents

Kun ZHOU, Jun LI, Jianhong LUO, Dongsheng ZHENG,

期刊论文

Multiple regression models for energy consumption of office buildings in different climates in China

Siyu ZHOU, Neng ZHU

期刊论文

Effectiveness of tertiary treatment processes in removing different classes of emerging contaminants

期刊论文

Sulfonic acid-functionalized mesoporous silica catalyst with different morphology for biodiesel production

期刊论文

Aerodynamic performance of bowed compressor cascades with different camber angles

CHEN Shaowen, CHEN Fu, WANG Keli, GU Jun, WANG Zhongqi

期刊论文

Removal efficiencies of natural and synthetic progesterones in hospital wastewater treated by different

期刊论文

Dynamic performance of submerged floating tunnel with different mooring styles subjected to anchor cable

期刊论文

Erratum to: Bending and vibration of a discontinuous beam with a curvic coupling under different axial

期刊论文

Elastic modulus and thermal stress in coating during heat cycling with different substrate shapes

Daniel GAONA,Alfredo VALAREZO

期刊论文