Most downloaded articles
2012, 34(2):69-76.
DOI: 10.11835/j.issn.1674-4764.2012.02.012
Abstract:
Seven specimens were loaded with axial force and horizontal cycle force to analyze the hysteretic performance and the influencing factor as well. The influence of axial compression ratio and aspect ratio on the hysteretic performance was investigated, including the buckling behaviors and the energy dissipation. And the positive role of combined effects on the hysteretic performance of cold-formed specimens was studied emphatically. The experiment reveals that a large axial compression ratio incurs a serious decrease on hysteretic performance, while the combined effects give an increase on it. In addition, the numerical mode is set up. Considering double nonlinearity, the results of experiment and simulation match each other well. Based on the data, it is obtained that local buckling plays a great negative role during the loading course. At last, the characteristics of hysteretic performance of cold-formed steel specimens are concluded and some suggestions are given.
Seven specimens were loaded with axial force and horizontal cycle force to analyze the hysteretic performance and the influencing factor as well. The influence of axial compression ratio and aspect ratio on the hysteretic performance was investigated, including the buckling behaviors and the energy dissipation. And the positive role of combined effects on the hysteretic performance of cold-formed specimens was studied emphatically. The experiment reveals that a large axial compression ratio incurs a serious decrease on hysteretic performance, while the combined effects give an increase on it. In addition, the numerical mode is set up. Considering double nonlinearity, the results of experiment and simulation match each other well. Based on the data, it is obtained that local buckling plays a great negative role during the loading course. At last, the characteristics of hysteretic performance of cold-formed steel specimens are concluded and some suggestions are given.
2 Influence factors of normal bonding properties between mortar and mechanical pressing raw-soil brick
2018, 40(1):78-82.
DOI: 10.11835/j.issn.1674-4764.2018.01.011
Abstract:
In order to investigate the influence factors of normal bonding properties between mortar and mechanical pressing raw-soil brick, the tensile bond strength test was made between mortar and mechanical pressing raw-soil brick with different interfacial condition.There were 72 specimens in total and three ages including 7d, 14d and 28d.The failure mode and the change rules of normal adhesive strength in different ages between raw-soil brick and mortar were explored. The influence of interfacial condition and ages on normal adhesive strength and failure mode was studied. The results show that interfacial condition and ages both have an influence on normal adhesive strength, which is improved along with ages and is decreased because of roughing. The normal bonding properties between mortar and mechanical pressing raw-soil brick is impacted by the type of mortar evidently. The reference for engineering application of raw soil mechanism brick is provided by the research results.
In order to investigate the influence factors of normal bonding properties between mortar and mechanical pressing raw-soil brick, the tensile bond strength test was made between mortar and mechanical pressing raw-soil brick with different interfacial condition.There were 72 specimens in total and three ages including 7d, 14d and 28d.The failure mode and the change rules of normal adhesive strength in different ages between raw-soil brick and mortar were explored. The influence of interfacial condition and ages on normal adhesive strength and failure mode was studied. The results show that interfacial condition and ages both have an influence on normal adhesive strength, which is improved along with ages and is decreased because of roughing. The normal bonding properties between mortar and mechanical pressing raw-soil brick is impacted by the type of mortar evidently. The reference for engineering application of raw soil mechanism brick is provided by the research results.
2012, 34(Z1):116-119.
Abstract:
For multilayer concrete structure, the seismic ability of the ground floor column is very poor, improving the seismic fortification intensity of structure is adopted in this paper, the axial force, shear and moment of beam and column are calculated and analyzed in seven degree and eight degree seismic fortification intensity. Numerical results show that with improving the fortification intensity of the structure, the axial force, shear and moment of beam and column increase and the change of the ground floor is the most prominent. In earthquake the destruction of the structure mainly happens in the ground floor column, so this problem is solved fundamentally with increasing fortification intensity in architectural design.
For multilayer concrete structure, the seismic ability of the ground floor column is very poor, improving the seismic fortification intensity of structure is adopted in this paper, the axial force, shear and moment of beam and column are calculated and analyzed in seven degree and eight degree seismic fortification intensity. Numerical results show that with improving the fortification intensity of the structure, the axial force, shear and moment of beam and column increase and the change of the ground floor is the most prominent. In earthquake the destruction of the structure mainly happens in the ground floor column, so this problem is solved fundamentally with increasing fortification intensity in architectural design.
2011, 33(1):77-86.
DOI: 10.11835/j.issn.1674-4764.2011.01.014
Abstract:
Based on fuzzy self-adapting stochastic damage model, the characteristics of generalized damage stress field on material crack tip are studied. The results express that the numerical algorithm is reliable. Sensitivity of rolled-concrete gravity dam under fuzzy-stochastic damage gaining is implemented by considering the spatial variation of material parameters. It is found that the compression strength of rolled-concrete is the governing index on gravity dam reliability. The activation simulations on fuzzy self-adapting stochastic damage model were carried by adopting different fuzzy distributions, which indicated the governing characteristics of the distribution on generalized damage evolution of rock-like material.
Based on fuzzy self-adapting stochastic damage model, the characteristics of generalized damage stress field on material crack tip are studied. The results express that the numerical algorithm is reliable. Sensitivity of rolled-concrete gravity dam under fuzzy-stochastic damage gaining is implemented by considering the spatial variation of material parameters. It is found that the compression strength of rolled-concrete is the governing index on gravity dam reliability. The activation simulations on fuzzy self-adapting stochastic damage model were carried by adopting different fuzzy distributions, which indicated the governing characteristics of the distribution on generalized damage evolution of rock-like material.
5 Nonlinear behavior of pilesunder inclined and eccentric loads indouble layered soils by model test
2018, 40(1):68-77.
DOI: 10.11835/j.issn.1674-4764.2018.01.010
Abstract:
A new hyperbolic p-y curve was derived to generally simulate then onlinearity of piles in layered soils, and the new p-y curve was presented containing parameters such as the initial ratio of elastic foundation coefficient, the initial elastic foundation coefficient,characteristic value of lateral displacementfor soils, and etc.. Model test of six timber piles and two steel piles in two groups settled in layer soils with upper clay and lower sand were done. The calculated lateral displacements of model piles both at the top and at the ground are consistent with the test values by p-y curve method, and the new hyperbolic p-y curve is verified. While the characteristic value of lateral displacement for layered soils increases, the displacement and the maximum bending moment of the pile decrease, the maximum shear and the maximum soil pressure around the pile increase. The variety of characteristic value of lateral displacement for the lower sand has extremely small effect on mechanical property of the pile, then the characteristic value of lateral displacement for lower soils can be defined as the same as that of the top soil during engineering application.
A new hyperbolic p-y curve was derived to generally simulate then onlinearity of piles in layered soils, and the new p-y curve was presented containing parameters such as the initial ratio of elastic foundation coefficient, the initial elastic foundation coefficient,characteristic value of lateral displacementfor soils, and etc.. Model test of six timber piles and two steel piles in two groups settled in layer soils with upper clay and lower sand were done. The calculated lateral displacements of model piles both at the top and at the ground are consistent with the test values by p-y curve method, and the new hyperbolic p-y curve is verified. While the characteristic value of lateral displacement for layered soils increases, the displacement and the maximum bending moment of the pile decrease, the maximum shear and the maximum soil pressure around the pile increase. The variety of characteristic value of lateral displacement for the lower sand has extremely small effect on mechanical property of the pile, then the characteristic value of lateral displacement for lower soils can be defined as the same as that of the top soil during engineering application.
2010, 32(5):65-70.
DOI: 10.11835/j.issn.1674-4764.2010.05.012
Abstract:
In the process of air conditioning, not only the thermal comfort but also energy saving should be considered. A method, which combines a least enthalpy difference（LED） and mixing air ratio based on the theory of enthalpy, can help to approach to comfortable zone for the air before coming into air handling unit (AHU). Then several mathematic equations of mixing process were derived based on laws of conservation of mass and energy. Eventually, the models of HVAC were established under SIMULINK environment. And the control strategies are validated in the aspects of improving comfortable effect and saving energy. It is found that LED based PID controller can achieve the requirements of better thermal comfort and energy efficiency.
In the process of air conditioning, not only the thermal comfort but also energy saving should be considered. A method, which combines a least enthalpy difference（LED） and mixing air ratio based on the theory of enthalpy, can help to approach to comfortable zone for the air before coming into air handling unit (AHU). Then several mathematic equations of mixing process were derived based on laws of conservation of mass and energy. Eventually, the models of HVAC were established under SIMULINK environment. And the control strategies are validated in the aspects of improving comfortable effect and saving energy. It is found that LED based PID controller can achieve the requirements of better thermal comfort and energy efficiency.
Wei Chaohai
,
Zhou Hongtao
,
Huang Jing
,
Wei Cong
,
Yang Xingzhou
,
Wei Jingyue
,
Li Zemin
,
Hu Yun
,
Ren Yuan
2019, 41(5):151-163.
DOI: 10.11835/j.issn.2096-6717.2019.106
Abstract:
Wastewater treatment is a complex process with high energy consumption and low efficiency. Different from the traditional concept of wastewater treatment, the pollutants contained of wastewater can be regarded as energy materials or as the raw materials of other products to be havested to reduce the energy consumption. The forms of the pollutants' embodied energy in wastewater were examined by employing two calculation methods and taking sewage and coking wastewater as examples. Moreover, two possible path ways for the utilization and maximization of the recovery of embodied energy during the wastewater treatment were discussed. The different forms of energy consumption and their causes in wastewater treatment process were analyzed based on thermodynamic laws and quality characteristics of the wastewater, with reasonable assumptions. The laws of energy transfer and distribution of two specific cases are expressed by the energy flow diagram. Some possible energy-saving approaches and wastewater treatment methods in the future are predicted by comparing different energy saving technologies. Based on in-depth understanding of the embodied energy in wastewaters, valuable elements such as nutrients (nitrogen, phosphorus) and heavy metals can be separated and recovered, and water resources can be reused by combining with related industries and technologies. Therefore, the goal of energy saving can be achieved by the indirect compensation of energy consumption in the wastewater treatment process.
Wastewater treatment is a complex process with high energy consumption and low efficiency. Different from the traditional concept of wastewater treatment, the pollutants contained of wastewater can be regarded as energy materials or as the raw materials of other products to be havested to reduce the energy consumption. The forms of the pollutants' embodied energy in wastewater were examined by employing two calculation methods and taking sewage and coking wastewater as examples. Moreover, two possible path ways for the utilization and maximization of the recovery of embodied energy during the wastewater treatment were discussed. The different forms of energy consumption and their causes in wastewater treatment process were analyzed based on thermodynamic laws and quality characteristics of the wastewater, with reasonable assumptions. The laws of energy transfer and distribution of two specific cases are expressed by the energy flow diagram. Some possible energy-saving approaches and wastewater treatment methods in the future are predicted by comparing different energy saving technologies. Based on in-depth understanding of the embodied energy in wastewaters, valuable elements such as nutrients (nitrogen, phosphorus) and heavy metals can be separated and recovered, and water resources can be reused by combining with related industries and technologies. Therefore, the goal of energy saving can be achieved by the indirect compensation of energy consumption in the wastewater treatment process.
2010, 32(4):85-89.
DOI: 10.11835/j.issn.1674-4764.2010.04.017
Abstract:
The influence of luminance level on students’ productivity, asthenopia (an eye strain), and brainfag (a mental exhaustion and depressive disorder) was studied with three typical colour temperatures of T5 fluorescent lamps. The changing rate of productivity and asthenopia were measured by using anomalistic distance determination and Анфимов alphabet test method and the changing rate of productivity was regarded as the brainfag index. It is found that medium colour temperature fluorescent lamps with appropriate exposure time can produce desirable consequences, stimulate the subjects’ cognitive ability and enhance their productivity. However, some lamps with lower or higher colour temperature produced undesirable consequences. The optimal luminances levels were thus variable and correspond to the colour temperature of lamps. The worst combination of colour temperature & luminance was identifies and should be avoided in classroom lighting design.
The influence of luminance level on students’ productivity, asthenopia (an eye strain), and brainfag (a mental exhaustion and depressive disorder) was studied with three typical colour temperatures of T5 fluorescent lamps. The changing rate of productivity and asthenopia were measured by using anomalistic distance determination and Анфимов alphabet test method and the changing rate of productivity was regarded as the brainfag index. It is found that medium colour temperature fluorescent lamps with appropriate exposure time can produce desirable consequences, stimulate the subjects’ cognitive ability and enhance their productivity. However, some lamps with lower or higher colour temperature produced undesirable consequences. The optimal luminances levels were thus variable and correspond to the colour temperature of lamps. The worst combination of colour temperature & luminance was identifies and should be avoided in classroom lighting design.
2012, 34(Z2):54-60.
Abstract:
This paper aims at providing a basic state-of-the-art of standards and guidelines, as well as laboratory and field studies dealing with whole-body vibration perception thresholds, and comparative analysis is given. Mechanisms of vibration perception, absolute thresholds of perception, difference thresholds and descriptors are introduced. The effects of frequency, posture, direction, duration, gender, age and noise on whole-body vibration perception thresholds are reviewed. And the problems requiring further investigation are proposed.
This paper aims at providing a basic state-of-the-art of standards and guidelines, as well as laboratory and field studies dealing with whole-body vibration perception thresholds, and comparative analysis is given. Mechanisms of vibration perception, absolute thresholds of perception, difference thresholds and descriptors are introduced. The effects of frequency, posture, direction, duration, gender, age and noise on whole-body vibration perception thresholds are reviewed. And the problems requiring further investigation are proposed.
2013, 35(2):66-72.
DOI: 10.3969/j.issn.1674-4764.2013.02.011
Abstract:
The heat conduction characteristic of glass curtain wall was investigated. Based on one dimensional steady heat conduction theory, the numerical calculation model of glass system thermal transmittance was set up by using insulating glass as an example. Based on two dimensional steady heat conduction theory and finite element method, both the thermal transfer matrix and temperature load array of 3 DOFs triangular element were derived. Then the revised formulas about the heat transfer matrix and temperature load array under the boundary conditions of constant heat flux, heat convective, radiation and coupled of them were also derived. Then the numerical calculation models of glass curtain wall frame and linear thermal transmittance were set up. The program TJCW based on the Visual C++ and ObjectARX was developed for calculating the thermal transmittance of glass curtain wall and was validated by contrast with the results calculated by thermal software LBNL. Finally, TJCW program was used to calculate and check the thermal transmittance of glass curtain wall in a practical project. The results indicate that the thermal transmittance of glass curtain wall can be calculated correctly by adopting the presented model, and the program based on this model can be used in energy conservation calculation and analysis in the actual projects.
The heat conduction characteristic of glass curtain wall was investigated. Based on one dimensional steady heat conduction theory, the numerical calculation model of glass system thermal transmittance was set up by using insulating glass as an example. Based on two dimensional steady heat conduction theory and finite element method, both the thermal transfer matrix and temperature load array of 3 DOFs triangular element were derived. Then the revised formulas about the heat transfer matrix and temperature load array under the boundary conditions of constant heat flux, heat convective, radiation and coupled of them were also derived. Then the numerical calculation models of glass curtain wall frame and linear thermal transmittance were set up. The program TJCW based on the Visual C++ and ObjectARX was developed for calculating the thermal transmittance of glass curtain wall and was validated by contrast with the results calculated by thermal software LBNL. Finally, TJCW program was used to calculate and check the thermal transmittance of glass curtain wall in a practical project. The results indicate that the thermal transmittance of glass curtain wall can be calculated correctly by adopting the presented model, and the program based on this model can be used in energy conservation calculation and analysis in the actual projects.
2018, 40(1):122-128.
DOI: 10.11835/j.issn.1674-4764.2018.01.017
Abstract:
The study of human body's radiation heat loss and thermal comfort need to calculate the angle factor between the human body and the envelope surfaces. Firstly, the paper derived the mathematical equation to revise the result of numerical calculation of angle factor based on the discrete formula of the angle factor and the effective radiation area, and established the standard three-dimensional body model of Chinese human in sitting posture. Then, the paper calculated the angle factor between the human body and roof, wall, floor, respectively, and found that the angle factor between the human body and the front surface is greater than the rear surface. Compared numerical calculation of angle factor with semi-analytical calculation, it is found that there are good agreements between semi-analytical calculation and numerical calculation for the roof and vertical wall, but there is a larger error for the floor, and the paper has modified these errors.
The study of human body's radiation heat loss and thermal comfort need to calculate the angle factor between the human body and the envelope surfaces. Firstly, the paper derived the mathematical equation to revise the result of numerical calculation of angle factor based on the discrete formula of the angle factor and the effective radiation area, and established the standard three-dimensional body model of Chinese human in sitting posture. Then, the paper calculated the angle factor between the human body and roof, wall, floor, respectively, and found that the angle factor between the human body and the front surface is greater than the rear surface. Compared numerical calculation of angle factor with semi-analytical calculation, it is found that there are good agreements between semi-analytical calculation and numerical calculation for the roof and vertical wall, but there is a larger error for the floor, and the paper has modified these errors.
12 Impact on Brain Wave Rhythm and Learning Efficiency by Color Temperature of Artificial Light Sources
2012, 34(1):76-79.
DOI: 10.11835/j.issn.1674-4764.2012.01.015
Abstract:
This experiment tests the change rate of students α & β brain waves under different illuminance levels combining with three color temperatures (CCTs) to indicate the influence of light spectrum on human physiological rhythm.The result shows that the brain electrical activities have significant differences under various CCTs and illuminance levels.The excitement and sensitivity of brain are roughly proportional to the light CCTs and illuminance. Brain electrical activities are more sensible to high CCT illuminations. Keeping mental work in the same time period with the same study intensities, brain fatigue comes earlier and stronger in excitable state at high illuminace and high CCT illumination than in peacful state at low illuminance and low CCT illumination.This situation leads to the learning efficiency of students decreased sharply.An interesting phenomena is that when working in low illuminance and low CCT environment, learning efficiency of students rises with time passing by.That indicates this kind of lighting environment may lead to awake effect of brain. In some environments which have the same illuminance levels with different CCTs that bring about the similar brain activities, learning efficient change rates are different because of the diversity of light spectrum which may induce the different stimulus intensity.Further research work is needed to explain this phenomenon.This experiment points out that the long-term mental workload character during the process of study and comprehensive effect of time accumulationmust be seriously considered in classroom lighting design.
This experiment tests the change rate of students α & β brain waves under different illuminance levels combining with three color temperatures (CCTs) to indicate the influence of light spectrum on human physiological rhythm.The result shows that the brain electrical activities have significant differences under various CCTs and illuminance levels.The excitement and sensitivity of brain are roughly proportional to the light CCTs and illuminance. Brain electrical activities are more sensible to high CCT illuminations. Keeping mental work in the same time period with the same study intensities, brain fatigue comes earlier and stronger in excitable state at high illuminace and high CCT illumination than in peacful state at low illuminance and low CCT illumination.This situation leads to the learning efficiency of students decreased sharply.An interesting phenomena is that when working in low illuminance and low CCT environment, learning efficiency of students rises with time passing by.That indicates this kind of lighting environment may lead to awake effect of brain. In some environments which have the same illuminance levels with different CCTs that bring about the similar brain activities, learning efficient change rates are different because of the diversity of light spectrum which may induce the different stimulus intensity.Further research work is needed to explain this phenomenon.This experiment points out that the long-term mental workload character during the process of study and comprehensive effect of time accumulationmust be seriously considered in classroom lighting design.
2011, 33(1):50-58.
DOI: 10.11835/j.issn.1674-4764.2011.01.010
Abstract:
The basic structure of Variable Curvature Friction Pendulum Isolation Bearing (VCFP) is introduced. Based on the principle of mechanical equilibrium, theoretical analysis on two types of VCFP which are Variable Frequency Pendulum Isolation Bearing (VFPI) and Conical Friction Pendulum Bearing (CFPI) are conducted. The stiffness of each VCFP is derived, and the recovery characteristics were discussed and the computing formula of maximum residual displacement was deduced as well. Moreover, with the use of ABAQUS software, the models with solid element of each VCFP are built, and the hysteresis property under low cyclic loading and recovery characteristic are simulated. The comparative analysis of VCFP and Friction Pendulum Bearing (FPB) are also conducted. The results show that: 1) the numerical simulation results are identical to the theoretical analysis; 2) according to its plump hysteresis loops, the hysteresis property of VCFP is favorable, further more, its effective viscous damping ratio and coefficient of energy dissipation are higher than FPB, which indicates its greater ability in energy dissipation; 3) the stiffness of the VCFP is determined by curvature radius, that is, sliding surface function. And its stiffness decreases with the increase of bearing displacement through rational design. And then its isolation period increases as the displacement increases and the low frequency resonance problem of isolated structures can be well solved; 4) compared with FPB, the softening mechanism of stiffness can make the shear force transferred to superstructure decrease; 5) the maximum stress of bearing appears when the bearing reaches its designed displacement, and in general it may situate in the edge of ball joint surface of slider or bearing plate 6) the maximum residual displacement of VCFP depends on both friction coefficient and the parameters of sliding surface function, therefore, parametric design based on analysis or simulation is necessary so as to control the maximum value in an acceptable range in engineering.
The basic structure of Variable Curvature Friction Pendulum Isolation Bearing (VCFP) is introduced. Based on the principle of mechanical equilibrium, theoretical analysis on two types of VCFP which are Variable Frequency Pendulum Isolation Bearing (VFPI) and Conical Friction Pendulum Bearing (CFPI) are conducted. The stiffness of each VCFP is derived, and the recovery characteristics were discussed and the computing formula of maximum residual displacement was deduced as well. Moreover, with the use of ABAQUS software, the models with solid element of each VCFP are built, and the hysteresis property under low cyclic loading and recovery characteristic are simulated. The comparative analysis of VCFP and Friction Pendulum Bearing (FPB) are also conducted. The results show that: 1) the numerical simulation results are identical to the theoretical analysis; 2) according to its plump hysteresis loops, the hysteresis property of VCFP is favorable, further more, its effective viscous damping ratio and coefficient of energy dissipation are higher than FPB, which indicates its greater ability in energy dissipation; 3) the stiffness of the VCFP is determined by curvature radius, that is, sliding surface function. And its stiffness decreases with the increase of bearing displacement through rational design. And then its isolation period increases as the displacement increases and the low frequency resonance problem of isolated structures can be well solved; 4) compared with FPB, the softening mechanism of stiffness can make the shear force transferred to superstructure decrease; 5) the maximum stress of bearing appears when the bearing reaches its designed displacement, and in general it may situate in the edge of ball joint surface of slider or bearing plate 6) the maximum residual displacement of VCFP depends on both friction coefficient and the parameters of sliding surface function, therefore, parametric design based on analysis or simulation is necessary so as to control the maximum value in an acceptable range in engineering.
2012, 34(5):25-32.
DOI: 10.3969/j.issn.1674-4764.2012.05.005
Abstract:
Through analysis of monitored ground settlements of Hangzhou Qing-chun Road cross-river tunnel, characteristics and influencing factors of ground settlements due to large-diameter slurry shield tunneling were summarized, and a modified hyperbolic model was proposed to predict the settlements. The results indicate that: 1.Peck equation is well used to predict ground settlements induced by slurry shield tunneling in Hangzhou district. The trough width parameter ranges from 0.25～0.32 while soil volume loss from 0.04%～0.33%. 2. Settlements before the shield tail leaving the monitoring sections are small, while soil closure at the shield tail and long-term consolidation settlements make most of the total settlements, with percentages of 57.27% and 41.08% respectively. 3. Increasing the pressure of slurry and synchronized grouting appropriately can counterbalance some ground loss, which can reduce the ground settlements. 4.Transverse ground settlements induced by ground loss represent the shape of Gaussian curve while heave movements behave irregularly. Ground heave movements due to large pressure of slurry and synchronized grouting often lead to the transverse ground settlements' deviation from Gaussian curve. 5. The modified hyperbolic model can be used to predict ground settlements due to slurry shielding in Hangzhou district with great accuracy.
Through analysis of monitored ground settlements of Hangzhou Qing-chun Road cross-river tunnel, characteristics and influencing factors of ground settlements due to large-diameter slurry shield tunneling were summarized, and a modified hyperbolic model was proposed to predict the settlements. The results indicate that: 1.Peck equation is well used to predict ground settlements induced by slurry shield tunneling in Hangzhou district. The trough width parameter ranges from 0.25～0.32 while soil volume loss from 0.04%～0.33%. 2. Settlements before the shield tail leaving the monitoring sections are small, while soil closure at the shield tail and long-term consolidation settlements make most of the total settlements, with percentages of 57.27% and 41.08% respectively. 3. Increasing the pressure of slurry and synchronized grouting appropriately can counterbalance some ground loss, which can reduce the ground settlements. 4.Transverse ground settlements induced by ground loss represent the shape of Gaussian curve while heave movements behave irregularly. Ground heave movements due to large pressure of slurry and synchronized grouting often lead to the transverse ground settlements' deviation from Gaussian curve. 5. The modified hyperbolic model can be used to predict ground settlements due to slurry shielding in Hangzhou district with great accuracy.
2012, 34(1):102-107.
DOI: 10.11835/j.issn.1674-4764.2012.01.020
Abstract:
Among all the measurement methods on activity of urease, indophenol blue colorimetric method, higher accuracy of the measurement results and better reproducibility, is the most widely used measurement method on activity of urease. However, this kind of method also owns some drawbacks, for examples, filtered fluid of cultivated soil is muddy and concentration of substrate has a great influence on the activity of urease. Based on the former measurement methods, four crucial parameters was taken to, such as method of filtration, time of cultivation, concentration of substrate and choice of buffer solution, the comparative tests in order to improve the accuracy of the measurement results of indophenol blue colorimetric method. The result of improved method is closer to the real activity of urease in soil with the conditions that choosing 5% concentration of substrate and pH10.0 borate buffer solution during the cultivation, extracting and filtrating with potassium chloride solution after 24-hours cultivation. The result of improved indophenol blue colorimetric method is 2.46 times better than the traditional method.
Among all the measurement methods on activity of urease, indophenol blue colorimetric method, higher accuracy of the measurement results and better reproducibility, is the most widely used measurement method on activity of urease. However, this kind of method also owns some drawbacks, for examples, filtered fluid of cultivated soil is muddy and concentration of substrate has a great influence on the activity of urease. Based on the former measurement methods, four crucial parameters was taken to, such as method of filtration, time of cultivation, concentration of substrate and choice of buffer solution, the comparative tests in order to improve the accuracy of the measurement results of indophenol blue colorimetric method. The result of improved method is closer to the real activity of urease in soil with the conditions that choosing 5% concentration of substrate and pH10.0 borate buffer solution during the cultivation, extracting and filtrating with potassium chloride solution after 24-hours cultivation. The result of improved indophenol blue colorimetric method is 2.46 times better than the traditional method.
2011, 33(4):60-64.
DOI: 10.11835/j.issn.1674-4764.2011.04.010
Abstract:
Based on the formal solutions of the buckling eigen equation,the probability density evolution equation for the random buckling eigenvalue is derived considering the random wind loading.Taking the averaged wind speed at 10m height and roughness length as the random factors,the random buckling bearing capacity for a super-high cooling tower is then analyzed.Furthermore,both the mean and the standard deviations of the capacity are calculated.It is indicated that there exhibits a general shape for the probability density function of the random buckling capacity.And the mean of the random buckling bearing capacity is close to that one computed by the averaged parameter.However,the variation of the random buckling bearing capacity is between the corresponding values of averaged wind speed at 10m height and roughness length.
Based on the formal solutions of the buckling eigen equation,the probability density evolution equation for the random buckling eigenvalue is derived considering the random wind loading.Taking the averaged wind speed at 10m height and roughness length as the random factors,the random buckling bearing capacity for a super-high cooling tower is then analyzed.Furthermore,both the mean and the standard deviations of the capacity are calculated.It is indicated that there exhibits a general shape for the probability density function of the random buckling capacity.And the mean of the random buckling bearing capacity is close to that one computed by the averaged parameter.However,the variation of the random buckling bearing capacity is between the corresponding values of averaged wind speed at 10m height and roughness length.
2011, 33(2):132-136.
DOI: 10.11835/j.issn.1674-4764.2011.02.026
Abstract:
Seepage resistance and moisture proof of concrete structure is a hard work in civil engineering. The influence factors of seepage resistance and moisture proof of concrete using ElectroOsmotic Pulse (EOP), such as electric voltage, water to cement ratio of concrete, ion concentration in liquid phase, and pulse frequency, were analyzed. Simulating experiment of EOP used to drain water and reduce relatively humidity of concrete structure is executed. The results show that, volume of water seepage is improved due to application of EOP in concrete with increase of electric voltage, W/C of concrete, and concentration of sodium sulfate. And pulse frequency has little effect on volume of water seepage. The results are also presented that effect of dewatering and humidity reducing are remarkable when EOP is applied in concrete structure.
Seepage resistance and moisture proof of concrete structure is a hard work in civil engineering. The influence factors of seepage resistance and moisture proof of concrete using ElectroOsmotic Pulse (EOP), such as electric voltage, water to cement ratio of concrete, ion concentration in liquid phase, and pulse frequency, were analyzed. Simulating experiment of EOP used to drain water and reduce relatively humidity of concrete structure is executed. The results show that, volume of water seepage is improved due to application of EOP in concrete with increase of electric voltage, W/C of concrete, and concentration of sodium sulfate. And pulse frequency has little effect on volume of water seepage. The results are also presented that effect of dewatering and humidity reducing are remarkable when EOP is applied in concrete structure.
2008, 30(6):81-85.
DOI: 10.11835/j.issn.1674-4764.2008.06.017
Abstract:
Urbanization in P. R. China inevitably boosts the development of urban subways. By summarizing the present situation of subway in China's major cities, we analyzed the formation and development of subway economics from the standpoint of urban subway development and forecast the arrival of a subway age. As a sunrise industry, the subway industry is the most promising with large market in the Chinese transportation infrastructure. Finally, a strategy of sustainable development for urban subways was put forward.
Urbanization in P. R. China inevitably boosts the development of urban subways. By summarizing the present situation of subway in China's major cities, we analyzed the formation and development of subway economics from the standpoint of urban subway development and forecast the arrival of a subway age. As a sunrise industry, the subway industry is the most promising with large market in the Chinese transportation infrastructure. Finally, a strategy of sustainable development for urban subways was put forward.
2018, 40(1):39-47.
DOI: 10.11835/j.issn.1674-4764.2018.01.006
Abstract:
Firstly, four groups of timber beams with shrinkage cracks in diversified depth were made and one-third loading method to observe the experimental data and record the ultimate bearing capacity was carried out. Then, according to the experimental data, combining finite element stress analysis, and the model of bilinear constitutive model of wood, the critical indicators which indicated that bending failure become shear failure and the corresponding ultimate bearing capacity formula were deduced. After that, the bearing capacity formula was simplified as the bearing capacity reduction coefficient curve. Finally, by comparing theoretical analysis with experiment, the results show that the theoretical values of ultimate bearing capacity coincide well with the test values, and the test phenomenon is consistent with the judgement of the critical indicator.
Firstly, four groups of timber beams with shrinkage cracks in diversified depth were made and one-third loading method to observe the experimental data and record the ultimate bearing capacity was carried out. Then, according to the experimental data, combining finite element stress analysis, and the model of bilinear constitutive model of wood, the critical indicators which indicated that bending failure become shear failure and the corresponding ultimate bearing capacity formula were deduced. After that, the bearing capacity formula was simplified as the bearing capacity reduction coefficient curve. Finally, by comparing theoretical analysis with experiment, the results show that the theoretical values of ultimate bearing capacity coincide well with the test values, and the test phenomenon is consistent with the judgement of the critical indicator.
