scholarly journals Quantification of Moment–Rotation Relationship of Monolithic Precast Beam–Column Connections

Buildings ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 11
Author(s):  
Baoxi Song ◽  
Weizhi Xu ◽  
Dongsheng Du ◽  
Shuguang Wang
Keyword(s):  
High Efficiency ◽  
Coupling Effect ◽  
Characteristic Point ◽  
Equivalent Model ◽  
Building Structures ◽  
Step Method ◽  
Nonlinear Structural ◽  
The Moment ◽  
Relationship Of

The accurate prediction of nonlinear structural behaviors under different seismic intensities is an important basis for seismic resilience assessments of building structures. The moment–rotation relationship is often used to characterize the seismic performance of connections, and is widely used in high-efficiency nonlinear structural analysis. In this paper, a method of calculating the curve using a four-linear equivalent model is presented, aiming to quantify the characteristic point parameters of the moment–rotation curves of monolithic precast beam–column (MPBC) connections for engineering design purposes. The method considered the contribution of the elastic flexure of beams and columns, the relative slip of beam longitudinal bars in the core zone, and the formation of plastic hinges at beam ends to the total deflection. Due to the presence of local complex configurations in MPBC connections, the fine fiber section method was used for moment–curvature analysis of critical beam sections. The determination of the sectional analysis processes was controlled by the strain of steel bars or concrete or their coupling effect. In addition, a two-step method was proposed to construct the moment–rotation relationship of cruciform beam–column connections for solving the deformation compatibility of beams on both sides of the column caused by asymmetric reinforcement and the strength difference between new and old concrete. To reflect the current manufacturing level of MPBC connections, 58 representative specimens reported in recent years were analyzed and classified as type 1–5. All types of MPBC connections and their 18 cast-in situ counterparts were calculated using the proposed method for both verification and quantification. The verification showed that the proposed method had good applicability to both cast-in situ and precast beam–column connections. The quantification showed that the characteristic point parameters were slightly different between these two connections. Accordingly, modification coefficients were suggested for MPBC connections to facilitate design.

scholarly journals Synthesis and photocatalytic activity of mesoporous g-C 3 N 4 /MoS 2 hybrid catalysts

2018 ◽  
Vol 5 (5) ◽  
pp. 180187 ◽  
Author(s):  
Yirong Qi ◽  
Qinghua Liang ◽  
Ruitao Lv ◽  
Wanci Shen ◽  
Feiyu Kang ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Carbon Nitride ◽  
Photocatalytic Performance ◽  
Coupling Effect ◽  
Charge Carriers ◽  
Step Method ◽  
Effective Suppression ◽  
Strong Coupling Effect ◽  
One Step

The key to solving environmental and energy issues through photocatalytic technology requires highly efficient, stable and eco-friendly photocatalysts. Graphitic carbon nitride (g-C 3 N 4 ) is one of the most promising candidates except for its limited photoactivity. In this work, a facile and scalable one-step method is developed to fabricate an efficient heterostructural g-C 3 N 4 photocatalyst in situ coupled with MoS 2 . The strong coupling effect between the MoS 2 nanosheets and g-C 3 N 4 scaffold, numerous mesopores and enlarged specific surface area helped form an effective heterojunction. As such, the photocatalytic activity of the g-C 3 N 4 /MoS 2 is more than three times higher than that of the pure g-C 3 N 4 in the degradation of RhB under visible light irradiation. Improvement of g-C 3 N 4 /MoS 2 photocatalytic performance is mainly ascribed to the effective suppression of the recombination of charge carriers.

scholarly journals Influence of Casting Solvents on CO2/CH4 Separation Using Polysulfone Membranes

Membranes ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 286
Author(s):  
Roba M. Almuhtaseb ◽  
Ahmed Awadallah-F ◽  
Shaheen A. Al-Muhtaseb ◽  
Majeda Khraisheh
Keyword(s):  
High Efficiency ◽  
In Situ Synthesis ◽  
Separation Process ◽  
Polymeric Membranes ◽  
Gas Mixture ◽  
Manufacturing Cost ◽  
Binary Gas Mixture ◽  
Maximum Permeability ◽  
Polysulfone Membranes

Polysulfone membranes exhibit resistance to high temperature with low manufacturing cost and high efficiency in the separation process. The composition of gases is an important step that estimates the efficiency of separation in membranes. As membrane types are currently becoming in demand for CO2/CH4 segregation, polysulfone will be an advantageous alternative to have in further studies. Therefore, research is undertaken in this study to evaluate two solvents: chloroform (CF) and tetrahydrofuran (THF). These solvents are tested for casting polymeric membranes from polysulfone (PSF) to separate every single component from a binary gas mixture of CO2/CH4. In addition, the effect of gas pressure was conducted from 1 to 10 bar on the behavior of the permeability and selectivity. The results refer to the fact that the maximum permeability of CO2 and CH4 for THF is 62.32 and 2.06 barrer at 1 and 2 bars, respectively. Further, the maximum permeability of CF is 57.59 and 2.12 barrer at 1 and 2 bars, respectively. The outcome selectivity values are 48 and 36 for THF and CF at 1 bar, accordingly. Furthermore, the study declares that with the increase in pressure, the permeability and selectivity values drop for CF and THF. The performance for polysulfone (PSF) membrane that is manufactured with THF is superior to that of CF relative to the Robeson upper bound. Therefore, through the results, it can be deduced that the solvent during in-situ synthesis has a significant influence on the gas separation of a binary mixture of CO2/CH4.

Experimental study of moment carrying behavior of typical Tibetan timber beam-column joints

2021 ◽  
pp. 136943322110015
Author(s):  
Ting Guo ◽  
Na Yang ◽  
Huichun Yan ◽  
Fan Bai
Keyword(s):  
Bending Moment ◽  
Structural Performance ◽  
Test Results ◽  
Timber Beam ◽  
Rotational Stiffness ◽  
Trilinear Model ◽  
Column Joint ◽  
Loading Tests ◽  
The Moment ◽  
Relationship Of

This study aimed to investigate the moment carrying behavior of typical Tibetan timber beam-column joints under monotonic vertical static load and also evaluate the influence of length ratio of Gongmu to beam (LRGB) and dowels layout on the structural performance of the joint. Six full-scale specimens were fabricated with same construction but different Gongmu length and dowels position. The moment carrying performance of beam-column joints in terms of failure mode, moment resistance, and rotational stiffness of joints were obtained via monotonic loading tests. Test results indicated that all joints are characterized by compressive failure perpendicular to grain of Ludou. Additionally, it was found that greater LRGB leads to greater initial rotational stiffness and maximum moment of the joint by an increase of restraint length for beam end; however, offsetting dowels toward column resulted smaller stiffness and ultimate bending moment of joints, particularly, offsetting Beam-Gongmu dowels toward column changed the moment-rotation curve pattern of the beam-column joint, accompanied by a hardening stiffness at last phase. Furthermore, a simplified trilinear model was proposed to represent the moment-rotation relationship of the typical Tibetan timber beam-column joint.

Study on Mechanical Automation with Design of Rapid Milk Detector Based on Freezing Point

2013 ◽  
Vol 703 ◽  
pp. 282-286
Author(s):  
Ren Cai Zhang ◽  
Xiang Yu ◽  
Xing Ju Liu ◽  
Jin Hai Zhai ◽  
Zhen Wu Ning
Keyword(s):  
Integrated Circuit ◽  
Temperature Sensor ◽  
High Efficiency ◽  
Freezing Point ◽  
Electronic Control ◽  
Freezing Point Depression ◽  
Electronic Control System ◽  
Freezing Curve ◽  
Rack Mechanism

An efficient automated milk detector based on freezing point depression is designed. This detector shares characters of high efficiency and good stability with accuracy and automation. Its main parts include temperature sensor of IC (Integrated Circuit), pinion-rack mechanism and crank-rocker mechanism and electronic control system. Monitoring in-situ change of milk freezing curve and developing efficiency of sampling can be available by means of pinion-rack mechanism and IC temperature sensor mechatronics design. As a result, adulterating status of milk can be discriminated in a rapid and accurate and automated way. The detector may be employed to detect liquid foods other than milk as well.

Separation of phenols from oils using deep eutectic solvents and ionic liquids

2020 ◽  
Vol 92 (10) ◽  
pp. 1717-1731
Author(s):  
Yucui Hou ◽  
Zhi Feng ◽  
Jaime Ruben Sossa Cuellar ◽  
Weize Wu
Keyword(s):  
Ionic Liquids ◽  
Phenolic Compounds ◽  
High Efficiency ◽  
Deep Eutectic Solvents ◽  
Environmentally Benign ◽  
Organic Chemical ◽  
Environmental Friendliness ◽  
Oil Mixtures ◽  
Organic Chemical Industry

AbstractPhenolic compounds are important basic materials for the organic chemical industry, such as pesticides, medicines and preservatives. Phenolic compounds can be obtained from biomass, coal and petroleum via pyrolysis and liquefaction, but they are mixtures in oil. The traditional methods to separate phenols from oil using alkaline washing are not environmentally benign. To solve the problems, deep eutectic solvents (DESs) and ionic liquids (ILs) have been developed to separate phenols from oil, which shows high efficiency and environmental friendliness. In this article, we summarized the properties of DESs and ILs and the applications of DESs and ILs in the separation of phenols and oil. There are two ways in which DESs and ILs are used in these applications: (1) DESs formed in situ using different hydrogen bonding acceptors including quaternary ammonium salts, zwitterions, imidazoles and amides; (2) DESs and ILs used as extractants. The effect of water on the separation, mass transfer dynamics in the separation process, removal of neutral oil entrained in DESs, phase diagrams of phenol + oil + extractant during extraction, are also discussed. In the last, we analyze general trends for the separation and evaluate the problematic or challenging aspects in the separation of phenols from oil mixtures.

scholarly journals Chromatin fibers observed in situ in frozen hydrated sections. Native fiber diameter is not correlated with nucleosome repeat length.

1994 ◽  
Vol 125 (1) ◽  
pp. 11-19 ◽  
Author(s):  
C L Woodcock
Keyword(s):  
Cell Types ◽  
Repeat Length ◽  
Strong Positive Correlation ◽  
Whole Cells ◽  
Chromosome Architecture ◽  
Chromatin Fibers ◽  
The Moment ◽  
Chicken Erythrocytes ◽  
Patiria Miniata

Chromatin fibers have been observed and measured in frozen hydrated sections of three types of cell (chicken erythrocytes and sperm of Patiria miniata and Thyone briareus) representing an approximately 20-bp range of nucleosomal repeat lengths. For sperm of the starfish P. miniata, it was possible to obtain images of chromatin fibers from cells that were swimming in seawater up to the moment of cryo-immobilization, thus providing a record of the native morphology of the chromatin of these cells. Glutaraldehyde fixation produced no significant changes in the ultrastructure or diameter of chromatin fibers, and fiber diameters observed in cryosections were similar to those recorded after low temperature embedding in Lowicryl K11M. Chromatin fiber diameters measured from cryosections of the three types of nuclei were similar, a striking contrast to the situation for chromatin isolated from these cell types, where a strong positive correlation between diameter and nucleosomal repeat length has been established. The demonstration of chromatin fibers in unfixed whole cells establishes an unequivocal baseline for the study of native chromatin and chromosome architecture. The significant differences between chromatin fibers in nucleo and after isolation supports a previous observation (P. J. Giannasca, R. A. Horowitz, and C. L. Woodcock. 1993. J. Cell Sci. 105:551-561), and suggests that structural studies on isolated material should be interpreted with caution until the changes that accompany chromatin isolation are understood.

Dynamic Modeling of the Torsional Vibration of the Slewing Mechanism of a Hydraulic Excavator

2012 ◽  
Vol 253-255 ◽  
pp. 2102-2106 ◽  
Author(s):  
Xu Juan Yang ◽  
Zong Hua Wu ◽  
Zhao Jun Li ◽  
Gan Wei Cai
Keyword(s):  
Torsional Vibration ◽  
Natural Frequencies ◽  
Planetary Gear ◽  
Moment Of Inertia ◽  
Hydraulic Excavator ◽  
Planetary Gear Trains ◽  
Vibration Model ◽  
Gear Trains ◽  
The Moment ◽  
Relationship Of

A torsional vibration model of the slewing mechanism of a hydraulic excavator is developed to predict its free vibration characteristics with consideration of many fundamental factors, such as the mesh stiffness of gear pairs, the coupling relationship of a two stage planetary gear trains and the variety of moment of inertia of the input end caused by the motion of work equipment. The natural frequencies are solved using the corresponding eigenvalue problem. Taking the moment of inertia of the input end for example to illustrate the relationship between the natural frequencies of the slewing mechanism and its parameters, based on the simulation results, just the first order frequency varies significantly with the moment of inertia of the input end of the slewing mechanism.

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