scholarly journals Preparation and Stability of Inorganic Solidified Foam for Preventing Coal Fires

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Botao Qin ◽  
Yi Lu ◽  
Fanglei Li ◽  
Yuwei Jia ◽  
Chao Zhu ◽  
...  
Keyword(s):  
Dynamic Change ◽  
Expansion Ratio ◽  
Hydration Products ◽  
Stability Coefficient ◽  
Aqueous Foam ◽  
Drainage Rate ◽  
Coal Fires ◽  
Novel Material ◽  
Stability Principle ◽  
The Stability

Inorganic solidified foam (ISF) is a novel material for preventing coal fires. This paper presents the preparation process and working principle of main installations. Besides, aqueous foam with expansion ratio of 28 and 30 min drainage rate of 13% was prepared. Stability of foam fluid was studied in terms of stability coefficient, by varying water-slurry ratio, fly ash replacement ratio of cement, and aqueous foam volume alternatively. Light microscope was utilized to analyze the dynamic change of bubble wall of foam fluid and stability principle was proposed. In order to further enhance the stability of ISF, different dosage of calcium fluoroaluminate was added to ISF specimens whose stability coefficient was tested and change of hydration products was detected by scanning electron microscope (SEM). The outcomes indicated that calcium fluoroaluminate could enhance the stability coefficient of ISF and compact hydration products formed in cell wall of ISF; naturally, the stability principle of ISF was proved right. Based on above-mentioned experimental contents, ISF with stability coefficient of 95% and foam expansion ratio of 5 was prepared, which could sufficiently satisfy field process requirements on plugging air leakage and thermal insulation.

scholarly journals Analysis and Calculation of Stability Coefficients of Cross-Laminated Timber Axial Compression Member

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4267
Author(s):  
Qi Ye ◽  
Yingchun Gong ◽  
Haiqing Ren ◽  
Cheng Guan ◽  
Guofang Wu ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Axial Compression ◽  
Calculation Method ◽  
National Standards ◽  
Test Results ◽  
Average Deviation ◽  
Stability Coefficient ◽  
Cross Laminated Timber ◽  
Stability Bearing Capacity ◽  
The Stability

Cross-laminated timber (CLT) elements are becoming increasingly popular in multi-storey timber-based structures, which have long been built in many different countries. Various challenges are connected with constructions of this type. One such challenge is that of stabilizing the structure against vertical loads. However, the calculations of the stability bearing capacity of the CLT members in axial compression in the structural design remains unsolved in China. This study aims to determine the stability bearing capacity of the CLT members in axial compression and to propose the calculation method of the stability coefficient. First, the stability coefficient calculation theories in different national standards were analyzed, and then the stability bearing capacity of CLT elements with four slenderness ratios was investigated. Finally, based on the stability coefficient calculation formulae in the GB 50005-2017 standard and the regression method, the calculation method of the stability coefficient for CLT elements was proposed, and the values of the material parameters were determined. The result shows that the average deviation between fitting curve and calculated results of European and American standard is 5.43% and 3.73%, respectively, and the average deviation between the fitting curve and the actual test results was 8.15%. The stability coefficients calculation formulae could be used to predict the stability coefficients of CLT specimens with different slenderness ratios well.

Evaluating second-order effects in rigid wall-flexible roof diaphragm buildings

2020 ◽  
Vol 36 (4) ◽  
pp. 1864-1885
Author(s):  
John Lawson ◽  
Maria Koliou
Keyword(s):  
Rigid Wall ◽  
The United States ◽  
Second Order ◽  
Order Effects ◽  
Building Stock ◽  
Stability Coefficient ◽  
Multistory Buildings ◽  
Flexible Diaphragm ◽  
Second Order Effects ◽  
The Stability

When evaluating seismically induced second-order effects in buildings, engineers and researchers are most familiar with these concerns in the context of multistory buildings with rigid diaphragms. However, similar concerns are valid for short single-story concrete or masonry-walled buildings with larger flexible diaphragms, which is a significant portion of the building stock in the United States. These rigid wall-flexible diaphragm (RWFD) buildings may have significant diaphragm drifts causing induced second-order effects. The stability coefficient currently found in ASCE 7 has traditionally been used by practitioners to evaluate the relative risk of P-delta instability in multistory buildings, but this indicator can be adapted for use in RWFD buildings. Using numerical studies following the Federal Emergency Management Agency (FEMA) P-695 collapse assessment methodology to evaluate the risk of collapse for a set of RWFD archetype buildings, a modified stability coefficient for RWFD buildings is found to capture the trend toward P-delta collapse and can act as a reasonable indicator without the need for heavy computational efforts.

Stability Coefficient of Interlocking Compressed Earth Block Masonry under Axial Compression

2020 ◽  
Author(s):  
Tianya Wang ◽  
Yihong Wang ◽  
Guiyuan Zeng ◽  
Jianxiong Zhang ◽  
Dan Shi
Keyword(s):  
Compressive Strength ◽  
Axial Compression ◽  
Design Guidelines ◽  
Stability Coefficient ◽  
Strength Failure ◽  
Compressed Earth Block ◽  
Out Of Plane ◽  
The Stability ◽  
Earth Block ◽  
Plane Deformations

To investigate the effects of the height-thickness ratio (β) on the mechanical properties and stability coefficients (φs) of interlocking compressed earth block (ICEB) masonry members under axial compression, four groups of specimens with different β of 3.75, 6.75, 11.25, and 14.25 were tested, thereby assessing their stress process, failure mode, compressive strength, and in- and out-of-plane deformations. All the specimens underwent brittle failure under axial compression: the compressive strength was found to decrease in a range from 5.6% to 43% with increasing β, whereas the initial stacking defects and the in- and out-of-plane deformations increased. The specimens became less stable, and we noticed that the overall damage was caused by strength failure and not instability failures. Because the stability coefficient of ICEB-based masonry components cannot be calculated as those of more conventional brickwork, we combined our results with well-established masonry design guidelines and derived an interlocking improvement coefficient.

Study on Evaluation of High Slope Stability and Countermeasures Based on GEO-SLOPE

2014 ◽  
Vol 988 ◽  
pp. 371-376
Author(s):  
Nian Qin Wang ◽  
Qing Tao Wang ◽  
Qi Pang ◽  
Qian Xue
Keyword(s):  
Slope Stability ◽  
Limit Equilibrium ◽  
Optimization Analysis ◽  
High Slope ◽  
Stability Coefficient ◽  
Anchor Cable ◽  
Before And After ◽  
The Stability ◽  
Reinforcement Measures

Based on the theory of limit equilibrium, by the GEO-SLOPE software,analyzed the stability before and after reinforcement of a high Loess-bedrock slope. The results and conclusions show: (1)Analyzed and Optimized the high Loess-bedrock slope through SLOPE/W module, optimizing the engineering quantity of the anchor cable frame in the local and saving the investment; (2)When taken reinforcement measures, conducted the SLOPE/W model again, the stability coefficient is 1.459, the effect testified by projects is obvious; (3)Aiming at the optimization analysis, proposed countermeasures system, with reference for reinforcement of a high Loess-bedrock slope.

Adaptive Backstepping Control of the Gripping Process of Heavy Manipulators

2017 ◽  
Author(s):  
Lixin Yang ◽  
Xianmin Zhang
Keyword(s):  
Tracking Control ◽  
Hydraulic Drive ◽  
Adaptive Controller ◽  
Drive System ◽  
Uncertain Parameters ◽  
Backstepping Method ◽  
Nonlinear Characteristics ◽  
Cylinder Model ◽  
Stability Principle ◽  
The Stability

A valve-controlled asymmetrical cylinder model was established to study the gripping hydraulic drive system of the grip device of heavy manipulator. Due to the strong nonlinear characteristics and uncertain parameters of the model, the Lyapunov stability principle was used to design a multistage inversion adaptive controller based on backstepping method and by introducing the virtual control parameter. The simulation results reveal that the tracking control and adaptive of uncertain parameters are very effective, which confirm that the designed controller can guarantee the stability of the closed-loop clamping hydraulic drive system.

Application of the Stability Coefficient for Considering Intrinsic Variability of Postural Sway

2019 ◽  
Vol 20 (3) ◽  
pp. 443-449
Author(s):  
Dongwon Kang ◽  
Jeongwoo Seo ◽  
Junggil Kim ◽  
Jinsoo Lee ◽  
Jinseung Choi ◽  
...  
Keyword(s):  
Postural Sway ◽  
Intrinsic Variability ◽  
Stability Coefficient ◽  
The Stability

scholarly journals Stability Analysis of Hydrodynamic Pressure Landslides with Different Permeability Coefficients Affected by Reservoir Water Level Fluctuations and Rainstorms

Water ◽  
2017 ◽  
Vol 9 (7) ◽  
pp. 450 ◽  
Author(s):  
Faming Huang ◽  
Xiaoyan Luo ◽  
Weiping Liu
Keyword(s):  
Water Level ◽  
Permeability Coefficient ◽  
Hydrodynamic Pressure ◽  
Water Level Fluctuations ◽  
Reservoir Water ◽  
Reservoir Water Level ◽  
Stability Coefficient ◽  
Permeability Coefficients ◽  
Landslide Stability ◽  
The Stability

It is significant to study the variations in the stability coefficients of hydrodynamic pressure landslides with different permeability coefficients affected by reservoir water level fluctuations and rainstorms. The Sifangbei landslide in Three Gorges Reservoir area is used as case study. Its stability coefficients are simulated based on saturated-unsaturated seepage theory and finite element analysis. The operating conditions of stability coefficients calculation are reservoir water level variations between 175 m and 145 m, different rates of reservoir water level fluctuations, and a three-day continuous rainstorm. Results show that the stability coefficient of the hydrodynamic pressure landslide decreases with the drawdown of the reservoir water level, and a rapid drawdown rate leads to a small stability coefficient when the permeability coefficient ranges from 1.16 × 10−6 m/s to 4.64 × 10−5 m/s. Additionally, the landslide stability coefficient increases as the reservoir water level increases, and a rapid increase in the water level leads to a high stability coefficient when the permeability coefficient ranges from 1.16 × 10−6 m/s to 4.64 × 10−5 m/s. The landslide stability coefficient initially decreases and then increases as the reservoir water level declines when the permeability coefficient is greater than 4.64 × 10−5 m/s. Moreover, for structures with the same landslide, the landslide stability coefficient is most sensitive to the change in the rate of reservoir water level drawdown when the permeability coefficient increases from 1.16 × 10−6 m/s to 1.16 × 10−4 m/s. Additionally, the rate of decrease in the stability coefficient increases as the permeability coefficient increases. Finally, the three-day rainstorm leads to a significant reduction in landslide stability, and the rate of decrease in the stability coefficient initially increases and then decreases as the permeability coefficient increases.

Excitation Action Triggered by Perilous Rock Avalanche to the Stability of Perilous Rock

2013 ◽  
Vol 368-370 ◽  
pp. 1633-1639 ◽  
Author(s):  
Hong Mei Tang ◽  
Lin Feng Wang ◽  
Hong Kai Chen ◽  
Zhi Wang
Keyword(s):  
Rock Avalanche ◽  
Normal Incidence ◽  
Combined Stress ◽  
Intensity Factors ◽  
Excitation Wave ◽  
Stability Coefficient ◽  
Horizontal Stability ◽  
The Stability ◽  
Important Significance ◽  
Rock Physical Model

The mechanism failure of massive perilous rock should consider the interaction among perilous rock masses. Study on the stability of adjacent perilous rock from the excitation wave, which is produced by the perilous rock mass at the collapse instantaneousness, has important significance. Focusing on the falling-type perilous rock, physical model of perilous rock with excitation wave is considered and the stress characteristics for the excitation wave of perilous rock avalanche on dominant fissure with normal incidence is analyzed. Based on the fracture mechanics, a method to calculate the combined stress intensity factors of dominant fissure under falling excitation action of perilous rock is established. As the instance results showed, two cites of nature and rainfall, the stability coefficient are both reduce, specially in the horizontal, stability coefficient reduced by about 10% respectively, while in vertical about 2%. The results provided some scientific progresses disasters prevention and mitigation of perilous rock.

Stability and Safety Analysis of Braced Excavation for Subway Station during Construction under the Condition of Side Slope

2011 ◽  
Vol 99-100 ◽  
pp. 1166-1170 ◽  
Author(s):  
Yuan Hai Li ◽  
Ping Liu ◽  
Ji Qiang Liu ◽  
Xue Feng Han
Keyword(s):  
Safety Analysis ◽  
Construction Safety ◽  
The Other ◽  
Steel Pipe ◽  
Subway Station ◽  
Stability Coefficient ◽  
Braced Excavation ◽  
Side Slope ◽  
The Stability ◽  
Design And Construction

The main purpose of this paper is to analyze the stability and safety problems of braced excavation enclosure, surrounding strata and side slope during construction of Shangshuijing station in Shenzhen Metro Line 5. The paper presents stability discrimination of the braced excavation and side slope by discussing their force and deformation regularity using Flac3D, and puts forward some project proposals about its design and construction. The results show that: (1) The stability coefficient of braced excavation enclosure becomes smaller because of biasing impact of side slope, but this project can meet the stability requirements, (2) The biasing impact of side slope has little influence on deformation of surrounding strata starting on the other side of braced excavation without slope, and (3) To ensure construction safety under condition of side slope, the braced excavation should be excavated starting from the zone far from the side slope, steel pipe can be used as assistant reinforcement at the corner of side slope if necessary.

scholarly journals Dynamic Changes in Plasma Urotensin II and its Correlation with Plaque Stability

2020 ◽  
Author(s):  
Chunlin Yin ◽  
Xue Liu ◽  
Hongxia Wang ◽  
Mingcong Yan ◽  
Lijuan Guo ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Vulnerable Plaque ◽  
Gene Transfection ◽  
Dynamic Change ◽  
High Cholesterol Diet ◽  
Atherosclerotic Plaques ◽  
Urotensin Ii ◽  
Plaque Instability ◽  
Coronary Syndrome ◽  
The Stability

Abstract Background: Urotensin II (UII) is involved in the formation of atherosclerosis, but its role in the stability of atherosclerotic plaque is undetermined. The purpose of this study was to observe the dynamic change of plasma UII and analyze its relationship with the stability of atherosclerotic plaques. Methods: The plasma UII concentration in patients with acute coronary syndrome (ACS) was detected. A vulnerable plaque model was established by local transfection of a recombinant P53 adenovirus into plaques of rabbits fed with a high-cholesterol diet and subjected to balloon injury, to evaluate the stability of the atherosclerotic plaques. Results: Our results showed that the level of plasma UII was increased in ACS patients compared with healthy subjects. However, it was significantly decreased in ST-segment elevation myocardial infarction patients (STEMI) and increased again in acute myocardial infarction (AMI) patients that were discharged after three months. UII dynamic change and its correlation with plaques stabilities were further verified in rabbit with atherosclerotic vulnerable plaque. The UII level in rabbits was significantly decreased after P53 gene transfection which can lead to of plaque instability. Conclusions: In conclusion, the level of plasma UII was significantly decreased in ACS with STEMI, which may serve as a reliable biological marker to reflect the progression and stability of atherosclerotic plaques.

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