It is challenging for most Historical Preservation Areas (HPA) to improve thermal comfort, especially under the contradiction of urban preservation. The study selected the Badaguan District as the ...object, which is the most famous HPA in Qingdao. Simulation is conducted by ENVI-met based on field measurements. Taking the current situation (green space 46.6% and building density 17.8%) as the basic case, we modeled two cases (reducing the green space to 29.1% and increasing the building density to 29.9% respectively according to the local standard). The results show that: (1) There are significant differences in air temperature and relative humidity among different streets; (2) District parameters including sky view factor (SVF) and Aspect Ratio(H/W) have different impact on microclimate; (3) Reducing the percentage of the green space(GS) to 29.1% (Case Ⅰ)and increasing the percentage of the building density(BD) to 29.9% (Case Ⅱ) both make the microclimate deteriorate. (4) By comparing the thermal comfort calendars of three cases, the thermal environment of the basic case is the best, and thermal environment of Case II is the worst especially at 12:00. The study can inform policy makers and urban designers to discover the balance between preservation of HPA and thermal environment improvement.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
We developed a conceptual design process model of the polymer-grade ethylene recovery process (SCOAS) from waste refinery gas using the oil absorption method. Based on the novel approach, heat ...pump-assisted thermal integration (HPSCOAS) is used to optimize and compare the traditional process. The results show that the novel processes show excellent technical, economic, and environmental performance.
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The direct emission of waste refinery gas after combustion will cause a severe greenhouse effect. Recovering high-value-added ethylene from wasted refinery gas has fundamental economic and environmental significance. Due to the complexity of the composition of refinery waste gas, designing and optimizing the whole recovery process is still a challenging task. Herein, a novel process (SCOAS) was proposed to obtain polymer-grade ethylene from wasted refinery gas through a direct separation process, and heat pump-assisted thermal integration optimization (HPSCOAS) was carried out. The unique feature of the novel approach is that a new stripper and ethylene reabsorber follow the dry gas absorber to ensure ethylene recovery and methane content. An industrial model, shallow cooling oil absorption (SCOA), and concentration combined cold separation system of ethylene unit using wasted refinery gas was established to analyze the technology and environment. Based on the detailed process modeling and simulation results, the quantitative sustainability assessment of economy and environment based on product life cycle process is carried out. The results show that compared with the traditional process when the same product is obtained, the total annual cost of the HPSCOAS process is the lowest, which is 15.4% lower than that of the SCOA process and 6.1% lower than that of the SCOAS process. In addition, compared with the SCOA process and the HPSCOAS process, the SCOAS process has more environmental advantages. The non-renewable energy consumed by SCOAS is reduced by about 24.8% and 6.1%, respectively. The CO2 equivalent is reduced by about 38.6% and 23.7%.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Sixteen full-scale recycled aggregate concrete (RAC) beams were cast and tested to study their time-dependent behavior under long-term loading. The test parameters include the replacement rate of the ...recycled coarse aggregates (RCAs), the replacement rate of the recycled fine aggregates (RFAs), the concrete strength, and the stress ratio. The influence of the above variables on the deflection and stiffness is discussed. The results show that the RCAs will increase the deflection of the specimen at a low stress ratio; at a high stress ratio, the beams will experience nonlinear creep, and the deflection of the specimen will be affected by the RCAs and the stress ratio. The RFAs have a substantial influence on the time-dependent behavior of the specimen, and the deflection of the specimen with 100% replacement of recycled aggregates can increase by 30%; the strength of the concrete does not have a substantial influence on the time-dependent behavior of the specimen; and the stress ratio has an influence on the initial deflection of the specimen. A deflection calculation formula is established based on the stress–strain relationship of the beam under long-term loading and the characteristics of the RAC. The calculation results are in good agreement with the test results.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Carbon species deposition is recognized as the primary cause of catalyst deactivation for hydrocarbon cracking and reforming reactions. Exploring the formation mechanism and influencing factors for ...carbon deposits is crucial for the design of rational catalysts. In this work, a series of NixMgyAl-800 catalysts with nickel particles of varying mean sizes between 13.2 and 25.4 nm were obtained by co-precipitation method. These catalysts showed different deactivation behaviors in the catalytic decomposition of methane (CDM) reaction and the deactivation rate of catalysts increased with the decrease in nickel particle size. Employing TG-MS and TEM characterizations, we found that carbon nanotubes which could keep catalyst activity were more prone to form on large nickel particles, while encapsulated carbon species that led to deactivation were inclined to deposit on small particles. Supported by DFT calculations, we proposed the insufficient supply of carbon atoms and rapid nucleation of carbon precursors caused by the lesser terrace/step ratio on smaller nickel particles, compared with large particles, inhibit the formation of carbon nanotube, leading to the formation of encapsulated carbon species. The findings in this work may provide guidance for the rational design of nickel-based catalysts for CDM and other methane conversion reactions.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
We demonstrate a highly sensitive and practical fiber-based temperature sensor system. The sensor is constructed based on a fiber ring laser (FRL) as well as a side-polished fiber filled with ...isopropanol. The laser cavity of the sensing part fiber is polished by the wheel fiber polishing system with residual thickness (RT) is selected to detect the temperature in the FRL. Thanks to the high thermo-optic coefficient of isopropanol, the sensitivity of the proposed temperature sensor could be effectively improved by filling isopropanol in the cost-less side polished single mode fiber. Refractive index (RI) of isopropanol changes with the surrounding temperature variation allowing high-sensitivity temperature sensing. Experimental results demonstrate that the side polished fiber can efficiently excite high-order cladding modes which enhance the modular interference increase the interaction between the evanescent wave and the isopropanol. Besides, the results show that the sensitivity can be as high as 2 nm/°C in the temperature range of 25–35 °C.
The present study was undertaken to evaluate the effect of surface hardening technology on dynamic frictional rolling contact behavior and degradation of corrugated rail in Shenzhen. Characteristic ...parameters such as length and depth of corrugation were analyzed by means of a continuous measurement method based on the corrugation analysis trolley. The explicit finite element method for material hardening characteristics and real contact geometry was adopted to set up the 3D transient FE model of wheel and rail, after which the value and distribution of stress/strain as well as contact solutions could be obtained during frictional contact, and then the Archard wear model and simplified wear superposition method are integrated as a numerical simulation tool for rail wear after hardening. The simulation results show that laminar plasma surface hardening technology can increase residual stress and shear stress in quenched zones, leading to local stress concentration at their boundaries; the plastic strain in the matrix material is higher than that in the quenched zones, while the strain concentration is mainly focused on the matrix material. The hardening can remarkably reduce the rail wear along the corrugation wave, and the wear depth of material with hardening technology is about 36% of that of nonhardening material. Laminar plasma surface hardening technology can therefore restrain the development of rail corrugation.
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DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
Development of effective ways to specifically and reversibly block the activity of an enzyme is highly desirable for enhancing the selectivity of enzyme assays. Here we demonstrate a novel approach ...for selective detection of enzyme activities in complex biological samples by using tailor-made nanoparticles. Employing deoxyribonuclease I (DNase I) as a model enzyme template, we prepared surface imprinted polymers over magnetic nanoparticles with monomers screened out of commonly used functional monomers. The resultant Fe3O4@MIP nanoparticles can not only block the activity of the target enzyme via selective adsorption but also quantitatively release the bound enzyme under mild conditions with the assistance of metal ion cofactors, which offers a very useful tool for enhancing the selectivity in enzyme detection. The approach enables sequential detection of the activities of 3′-5′ exonuclease and DNase I in cell lysates. The strategy may be further extended to the detection of other enzyme proteins.
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IJS, KILJ, NUK, PNG, UL, UM
A novel method for ultra-sensitive and ultra-fast temperature sensing has been successfully implemented by cascading Saganc rings to generate the Vernier effect and doing the same dispersive fibers ...to achieve the optical time-stretching effect. This is different from the traditional point fiber sensor demodulated by optical spectrum analyzer (OSA) whose demodulation speed is usually at the second level. The designed system maps the wavelength domain to the time domain through the dispersive fiber, which can realize the ultra-fast temperature monitoring at the nanosecond level. The cascaded Sagnac ring is composed of polarization maintaining fiber (PMF) which is significantly affected by the thermal-optical coefficient. When the temperature changes, the variation is as high as -6.228 nm/°C, which is 8.5 times higher than the sensitivity based on the single Sagnac ring system. Furthermore, through the optical time stretching scheme, the corresponding response sensitivity is increased from 0.997 ns/°C to 7.333 ns/°C, and the magnification is increased 7.4 times with a response speed of 50 MHz.
Upgrading of vacuum residue is of prime industrial significance due to the increasing demand for light oils. Elucidating the effect of catalyst morphology on vacuum residue hydrotreating performance ...by kinetic modeling is therefore of great importance. Herein, kinetic analysis of hydrodemetallization (HDM) and hydrodeconradson-carbon-residue (HDCCR) performances on industrial Ni–Mo/Al2O3 catalysts with spherical and cylindrical morphologies in ebullated-bed were evaluated for more than 1600 h. It was found that the percentage of light impurities easier to be removed on spherical catalysts were 78.20% and 39.43% in HDM and HDCCR reactions, respectively, higher than 65.20% and 17.50% on cylindrical catalysts. This suggests that catalyst morphology affects the impurity removal ability and the impurity properties, resulting in better hydrotreating performance of spherical catalysts. This work not only combines catalyst morphology with impurity removal capability through kinetic modeling, but also provides new insights into the design of efficient hydrotreating catalysts.
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• Kinetic modeling of vacuum residue hydrotreating for 1600 h was performed.• Catalyst morphology affects the impurity properties and the impurity removal ability.• Light impurities on spherical catalysts are more than those on cylindrical catalysts.• Spherical catalysts are more capable of removing impurities than cylindrical catalysts.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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