Seismic behavior and life-cycle cost effectiveness of steel moment resisting frame structures with self-centering friction-viscous dampers

The self-centering friction-viscous damper (SCFVD) is a novel self-centering system that utilizes preloaded ring springs to offer self-centering and friction-based energy dissipation capacity, while a viscous damper provides viscous-based energy dissipation capacity. This study is to study the seismic behavior of steel moment-resisting frames (MRFs) with SCFVDs, considering cost effectiveness. The mechanical model of the SCFVD is first presented and validated through pseudo-static tests on a full-scale specimen. Simulation models of 3-story, 9-story, and 20-story steel MRFs with SCFVDs and viscous dampers are then built, and numerical analysis under 40 earthquake records is conducted on them to compare and evaluate the structural peak dynamic response and energy dissipation from an economic perspective. The results show that the SCFVD's hysteretic response can be reliably predicted by the mechanical model. When compared to the uncontrolled steel-MRFs and the steel-MRFs with FVDs, the SCFVD can significantly mitigate structural peak and residual drift, especially under high-intensity earthquakes, but may aggravate structural peak acceleration. Besides, the SCFVD can mitigate the structural hysteretic energy dissipation and damage to the 3-story and 9-story steel MRFs. The cost/average reduction ratio of peak drift for the steel-MRFs with SCFVDs is reduced by 6.3% when compared to that for the steel-MRFs with FVDs

Synergetic Effect of Non-Condensable Gas and Steam Quality on the Production Capacity of Geothermal Wells and Geothermal Power Generation for Hot Dry Rock

This paper aims to fill the research gap on the effect of steam quality and non-condensable gas on heat-carrying fluid productivity, system performance and optimization. First, the effect of the temperature and quality of the heat-carrying fluid and non-condensable gas (NCG) content on the production parameters was evaluated. After that, three energy conversion systems which included a single flash (SF) system, an organic Rankine cycle (ORC) system and a single flash combined ORC (SFORC) system were constructed in this paper to utilize the heat-carrying two-phase flow with non-condensable gas. Finally, based on thermodynamic modeling, the effects of the temperature and quality of the heat-carrying fluid and non-condensable gas content on the performance and optimization of the three power conversion systems were investigated. The results show that single-phase heat-carrying fluids are more productive than two-phase heat-carrying fluids. NCG is always detrimental. The heat-carrying fluid temperature and quality are positively correlated with system efficiency and negatively correlated with the net power output. In the comparison of comprehensive performances, the SFORC system is the better, and the ORC system and the SF system are the worse. The optimal net power output of the SF system, the ORC system and the SFORC system is 4883 kW, 6557 kW and 7251 kW, respectively

Techno-economic and environmental performance of a novel poly-generation system under different energy-supply scenarios and temperature and humidity independent control

The stand-alone energy production for power generation, heating or cooling is an usual method for low-medium grade energy utilization. To enhance the energy utilization efficiency, a combined cooling, heating, and power (CCHP) system, which is based on two-stage vapor compression cycle (TSVCC) and organic Rankine cycle (ORC), is proposed with temperature and humidity independent control (THIC). The essential parameters are changed to enhance the CCHP performances based on the thermodynamic model constructed. Moreover, the cooling performance are evaluated under different energy-supply scenarios, and the coupling effects of the CCHP are demonstrated through the THIC strategies. The results display that when the return air and fresh air are treated with energy of corresponding grade respectively, the higher outdoor relative humidity and the lower fresh air ratios are beneficial for enhancing refrigeration performance. The adverse effects of condensation temperature on both the economic and environmental performance far surpasses that of sub-cooling degree. With a rise of 10 °C in condensation temperature and sub-cooling degree, the economic performance decreases by 27.89% and 3.7% respectively, while the environmental performance decreases by 24.33% and 0.35% respectively. Furthermore, the proposed system can be switched to variant models according to different strategies in seasons to improve efficiency of energy utilization, which could be used in engineering applications

Microseismic location uncertainties of semblance weighted stacking method: a synthetic case study

Microseismic imaging is a common technique for monitoring oilfield completion and production processes. Accurate imaging of the source location of the microseismic event is of imperative importance for accurate fracture mapping. In this study, we investigate uncertainties in the estimated locations of microseismic events given two different receiver array geometries by applying the semblance-weighted stacking location method to two simple synthetic examples.The error ellipsoid, i.e. the extent of the stack image at 50% of the maximum, is used as a relative measure of uncertainty in various directions. We illustrate how these errors are affected by the receiver array geometry itself and demonstrate that for same array sizes, reducing the number of receivers used in a monitoring project doesn't impact the estimated horizontal location of a microseismic event. We also present that a surface array with more receivers and smaller receiver spacing provides a better vertical resolution than a surface array with less receivers and larger receiver spacing

Seismic performance of RC bent columns: Experimental, numerical and life-cycle cost analysis

Reinforced concrete (RC) bent structures are widely used in single-story industrial buildings, with a considerable portion of them located in high-intensity seismic areas. Therefore, it is significant to study the seismic performance of the RC bent column while keeping construction costs in mind. To evaluate the seismic performance of the RC bent column from an economic perspective, pseudo-static tests combined with construction cost analysis were first carried out on three RC bent columns designed according to different versions of Chinese codes. A numerical simulation method based on the extended finite element method (XFEM) for the RC bent column was then established and verified. Subsequently, the relationship between the local damage index related to the apparent damage characteristics and the overall damage index was established by conducting numerical analysis on RC bent columns with different design parameters. Based on the established relationship between the local and overall damage indexes, a calculation method for the residual bearing capacity based on apparent damage was developed. The results show that, when compared to the constructional requirements in the Chinese code for seismic design of industrial and civil buildings published in 1978 (TJ11–78), the constructional requirements in the Chinese code for seismic design of buildings published in 1989 (GBJ11–89) can effectively reduce the stress concentration at the column bottom and delay the formation of the plastic hinge with minimal cost increase, while the constructional requirements in the Chinese code for seismic design of buildings published in 2016 (GB50011–2010) can further effectively reduce the damage to the upper column. Besides, the constructional requirements in GBJ11–89 and GB50011–2010 can improve the energy dissipation and maximum bearing capacity of the RC bent column while decrease the cost/ductility coefficient by more than 5.0 %. The proposed calculation method can effectively predict the residual bearing capacity of earthquake-damaged RC bent columns by comparing the calculation results to the test results

Thermodynamic Performance Comparison of CCHP System Based on Organic Rankine Cycle and Two-Stage Vapor Compression Cycle

Owing to different temperature rages of power generation and refrigeration in the cogeneration system, for the sake of selecting the working fluids that are suitable for both power generation and refrigeration simultaneously, 17 commonly used working fluids are evaluated in this paper, based on an organic Rankine cycle coupled with a two-stage vapor compression cycle system in different geothermal fluid temperatures. The performances of working fluids under different working conditions, and the maximum power generation as well as cooling capacity are analyzed. Additionally, the main parameters are analyzed to optimize the system performance. The results indicate that net power output has a local maximum where it corresponds to the optimal evaporation temperature. Besides, the lower the critical temperature, the greater the thermal conductance, and the pressure ratio decreases with evaporation temperature. Hydrocarbons all have higher total heat source recovery efficiency. R1234yf, propane and R1234ze, R152a have excellent maximum net power output when the geothermal fluid temperature is low and high, respectively. R134a always has better maximum net power output and cooling capacity. The net power output is used for cooling, and the COP is closed, therefore, maximum net power output results in the maximum cooling capacity. In addition, that of propane and R1234yf are excellent until the geothermal fluid temperature are 140 °C and 120 °C separately. R1234ze and R152a are good when the geothermal fluid temperatures are 140 °C and 150 °C, respectively

Effects of Impurity Doping on the Luminescence Performance of Mn4+-Doped Aluminates with the Magnetoplumbite-Type Structure for Plant Cultivation

Mn4+ activated LaMgAl11O19 (LMA/Mn4+) with red emitting phosphor was obtained by sintering under air conditioning. The X-ray diffraction pattern Rietveld refinement results reveal that three six-fold coordinated Al sites are substituted by Mn4+ ions. Furthermore, the chemical valence state of manganese in the LMA host was further confirmed through X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR). Photoluminescence emission (PL) and excitation (PLE) spectra of LMA/Mn4+ as well as the lifetime were measured, and the 663 nm emission is ascribed to the 2Eg→4A2g from the 3d3 electrons in the [MnO6]8− octahedral complex. The emission spectrum matches well with the absorption of phytochrome. Temperature-dependent PL spectra show that the color changes of the phosphor at 420 K are 0.0110 for Δx and −0.0109 for Δy. Moreover, doping Zn2+ and Mg2+ ions in the host enhances the emission intensity of Mn4+ ions. These results highlight the potential of LMA/Mn4+ phosphor for a light-emitting diode (LED) plant lamp

Overpressure: Origin, Prediction, and Its Impact in the Xihu Sag, Eastern China Sea

The complex relationship between deep overpressure, abnormal porosity, and hydrocarbon generation in the Pinghu Formation is interesting and challenging for hydrocarbon exploration and development in the East China Sea Shelf Basin. It shows three-stage pore pressure evolution based on the characteristics of logs in the west slope of the Xihu Sag. Disequilibrium compaction was identified as the dominant overpressure mechanism in stage II (1.0 < PC < 1.6). The fluid expansion was identified as the predominant mechanism of overpressure generation in stage III (PC > 1.6), and tectonic compression occurs in Well B. Pore pressure was predicated by the Fillippone method based on the combination of raw velocity spectra and high-resolution velocity parameters obtained by seismic inversion. The overpressure at the bottom of the Pinghu Formation is mainly distributed in the F2 and F3 fault blocks. The deep gas reservoir of the Pinghu Formation is controlled by both lithology and pressure. The overpressure distribution area is consistent with the center of hydrocarbon generation. The overpressure distribution illustrated that overpressure was positively correlated with the porosity and permeability of the reservoir. The first porosity and permeability inversion zone of the Pinghu Formation formed because the overpressure caused by under-compaction offsets the pressure of some overlying strata and slows down diagenesis. Due to a large amount of hydrocarbon generation in source rocks, the acidic fluid with high temperature promoted the development of secondary pores, resulting in the second pore permeability inversion zone of the Pinghu Formation. The index of porosity preserving (IPP) is proposed here to quantitatively describe the relationship between overpressure and porosity. The index of porosity preserving in the second stage is 1.16%/10 MPa, and in the third stage is 1.75%/10 MPa. The results can be used to guide the exploration of the deep-basin gas reservoir of the Xihu Sag in the Eastern China Sea Basin

Effect of laparoscopic splenectomy on portal vein thrombosis and serum YKL-40 in patients with cirrhotic portal hypertension

Introduction and objectives: Laparoscopic splenectomy (LS) is a supportive intervention for cirrhotic patients. However, its efficacy for patients with cirrhotic portal hypertension (CPH) still needs clarification. Studies indicated YKL-40 might be effective targets for treatment of splenomegaly, however deeper insights are unclear. The aim of this study was to investigate the effect of LS on the formation of portal vein thrombosis (PVT) and serum levels of a fibrosis marker, YKL-40, in patients with CPH. Materials and methods: A total of 80 patients who underwent LS and 30 healthy controls were investigated in this study. Serum levels of YKL-40 were measured by enzyme-linked immunosorbent assay (ELISA). Demographic characteristics including age and gender were recorded. Clinicopathological and laboratory examinations included the severity of esophageal varices and the presence of viral hepatitis. The liver function was assessed according to the Child–Pugh classification. The incidence of PVT before and after operation was also monitored. Results: Serum YKL-40 was significantly increased in CPH patients, and was associated with Child–Pugh score and HBV infection. Furthermore, elderly patients had an increased risk for postoperative PVT. Higher serum YKL-40 was observed in patients with thrombus at postoperative 7, 14 and 21 days than those without thrombus. Conclusions: LS could reduce serum YKL-40 levels and PVT progression and was a useful treatment for patients <40 years of age with CPH

An Unsupervised Learning Method for the Detection of Genetically Modified Crops Based on Terahertz Spectral Data Analysis

Genetically modified crops have been planted commercially on a large scale since 1996. However, the food safety issue of genetically modified crops remains controversial. Conventional genetically modified crops’ detection methods require a plenty of detective time and complex operations that cannot rapidly identify. Previous reports show that combining terahertz time-domain spectroscopy and supervised learning has advanced to identify genetically modified crops, but supervised learning requires large data to train the model. To solve the above problem, we proposed an unsupervised learning method, PCA-mean shift, to identify genetically modified crops. Principal component analysis was employed to reduce the absorbance data dimensionality. After principal component analysis, the first three principal components were used as the input of mean shift. At last, our proposed method had 100% identification accuracy, and K-means had 98.75% identification accuracy. The comparison results demonstrated that PCA-mean shift outperforms K-means. Therefore, PCA-mean shift combined with terahertz time-domain spectroscopy is a potential identification tool for genetically modified crops’ identification