In recent years,bamboo,as a green building material,has attracted more and more attention worldwide.Inspired by the investigation of cross-laminated timber in structural systems,a new engineered cross-laminated bamboo...In recent years,bamboo,as a green building material,has attracted more and more attention worldwide.Inspired by the investigation of cross-laminated timber in structural systems,a new engineered cross-laminated bamboo(CLB)consisting of the cross lamination of bamboo scrimber plates is proposed in this paper.To evaluate its potential in structural applications,the thermal insulation performances of the CLB walls and CLB walls with the EPS foam plate were studied and evaluated by the temperature-controlled box-heat flow meter method.Test results indicated that the thermal insulation performance improved with the increase of thickness,but different wall configurations had little effect on the thermal insulation performance under the same thickness of the CLB wall.The thermal insulation performance of EPS-CLB composite wall was much better than that of CLB wall.In addition,a relatively acceptable accuracy of the theoretical calculations was proved.Finally,the influence of different locations of the EPS foam plate on heat transfer coefficient can be neglected as it was studied based on the validated numerical models.展开更多
Two experimental methods were adopted to verify the correctness and practicability of the shape meter method: one is to roll aluminum plate, calculate the shape stiffness of mill and rolled piece, and then measure alu...Two experimental methods were adopted to verify the correctness and practicability of the shape meter method: one is to roll aluminum plate, calculate the shape stiffness of mill and rolled piece, and then measure aluminum plate crown to verify shape stiffness equation; the other is to calculate the measured off line data of hot continuous roll and verify the shape mathematical model for measuring and controlling by self adaptation method.展开更多
The velocity area method belongs to the group of primary methods for discharge measurement in hydropower plants. The measurements require an appropriate application of measuring devices and carrying out correctly the ...The velocity area method belongs to the group of primary methods for discharge measurement in hydropower plants. The measurements require an appropriate application of measuring devices and carrying out correctly the process of data analyzing including integration technique. The authors present their own experiences gathered during many years of utilizing the current meter method for discharge measurement in many hydropower plants. They have developed the special integration techniques using the progressive numerical algorithms. The techniques differ from the recommendations contained in the relevant international standards. The authors' own software for calculating the discharge from the measured local velocity distribution (obtained using current meters) adopts advanced spline functions, the so-called NURBS (non-uniform rational B-splines). Nowadays, this kind of splines is commonly used in modeling of the complex geometrical shapes because of their smoothness. It is assessed that it represents much better quality of interpolation than the classic spline functions (classic cubic spline technique). Particularly, the better properties of the NURBS splines can be observed for velocity profile area characterized by very strong velocity gradients where boundary layers meet the core regions of the flow (mainstream). In the developed software the boundary layer thickness and exponent of von Karman function is calculated in accordance with the ISO 3354 standard. The software has been successfully used during many performance tests of the hydraulic turbines in Poland for several years. Paper presents the results of flow rate measurements for two different flow systems of Kaplan turbines. First case concerns the application of the current meters in a long circular penstock whereas the second one in short rectangular turbine intake. A comparative analysis of three flow calculation procedures applied for these two cases is presented in the paper-(1) the integration procedure according to the ISO 3354 standard; (2) the integration procedure based on the NS (natural splines); and (3) the integration procedure based on the NURBS. The results obtained using these three procedures for the first case (intake via long circular penstock) were compared with the results of discharge measurements conducted using the pressure-time method.展开更多
The paper presents selected experience of the authors resulting from the optimization tests of double-regulated water turbines. Among the methods for measuring the discharge through the turbine used in such tests, par...The paper presents selected experience of the authors resulting from the optimization tests of double-regulated water turbines. Among the methods for measuring the discharge through the turbine used in such tests, particular attention was paid to index methods allowing to measure the relative discharge through the turbine-the index current meter method and the methods based on measuring the differential pressure between two points properly located at the turbine flow system (i.e., Winter-Kennedy method). These methods contribute to effective reduction of the cost of optimizing the turbine that is extremely important for small hydropower plants regarding installed capacity. The paper presents selected examples of the optimization tests and experiences that arise from these tests.展开更多
Squeezing flow of nanofluids has been taken into account under the effects of viscous dissipation and velocity slip.Two types of base fluids are used to study the behavior of Copper nanoparticles between parallel plat...Squeezing flow of nanofluids has been taken into account under the effects of viscous dissipation and velocity slip.Two types of base fluids are used to study the behavior of Copper nanoparticles between parallel plates.Nonlinear ordinary differential equations governing the flow are obtained by imposing similarity transformations on conservation laws.Resulting equations are solved by using an efficient analytical technique the variation of parameters method(VPM).Influences of nanoparticle concentration and different emerging parameters on flow profiles are presented graphically coupled with comprehensive discussions.A numerical solution is also sought for the sake of comparison.Effect of different parameters on skin friction coefficient and Nusselt number is also discussed.展开更多
基金from the National Natural Research and Development Fund(9Z05000049D0)Integrated Key Precast Components and New Wood-bamboo Composite Structure(2017YFC0703502).
文摘In recent years,bamboo,as a green building material,has attracted more and more attention worldwide.Inspired by the investigation of cross-laminated timber in structural systems,a new engineered cross-laminated bamboo(CLB)consisting of the cross lamination of bamboo scrimber plates is proposed in this paper.To evaluate its potential in structural applications,the thermal insulation performances of the CLB walls and CLB walls with the EPS foam plate were studied and evaluated by the temperature-controlled box-heat flow meter method.Test results indicated that the thermal insulation performance improved with the increase of thickness,but different wall configurations had little effect on the thermal insulation performance under the same thickness of the CLB wall.The thermal insulation performance of EPS-CLB composite wall was much better than that of CLB wall.In addition,a relatively acceptable accuracy of the theoretical calculations was proved.Finally,the influence of different locations of the EPS foam plate on heat transfer coefficient can be neglected as it was studied based on the validated numerical models.
基金Item Sponsored by National Natural Science Foundation of China(19974035)Natural Science Foundation of Hebei Province(599240)
文摘Two experimental methods were adopted to verify the correctness and practicability of the shape meter method: one is to roll aluminum plate, calculate the shape stiffness of mill and rolled piece, and then measure aluminum plate crown to verify shape stiffness equation; the other is to calculate the measured off line data of hot continuous roll and verify the shape mathematical model for measuring and controlling by self adaptation method.
文摘The velocity area method belongs to the group of primary methods for discharge measurement in hydropower plants. The measurements require an appropriate application of measuring devices and carrying out correctly the process of data analyzing including integration technique. The authors present their own experiences gathered during many years of utilizing the current meter method for discharge measurement in many hydropower plants. They have developed the special integration techniques using the progressive numerical algorithms. The techniques differ from the recommendations contained in the relevant international standards. The authors' own software for calculating the discharge from the measured local velocity distribution (obtained using current meters) adopts advanced spline functions, the so-called NURBS (non-uniform rational B-splines). Nowadays, this kind of splines is commonly used in modeling of the complex geometrical shapes because of their smoothness. It is assessed that it represents much better quality of interpolation than the classic spline functions (classic cubic spline technique). Particularly, the better properties of the NURBS splines can be observed for velocity profile area characterized by very strong velocity gradients where boundary layers meet the core regions of the flow (mainstream). In the developed software the boundary layer thickness and exponent of von Karman function is calculated in accordance with the ISO 3354 standard. The software has been successfully used during many performance tests of the hydraulic turbines in Poland for several years. Paper presents the results of flow rate measurements for two different flow systems of Kaplan turbines. First case concerns the application of the current meters in a long circular penstock whereas the second one in short rectangular turbine intake. A comparative analysis of three flow calculation procedures applied for these two cases is presented in the paper-(1) the integration procedure according to the ISO 3354 standard; (2) the integration procedure based on the NS (natural splines); and (3) the integration procedure based on the NURBS. The results obtained using these three procedures for the first case (intake via long circular penstock) were compared with the results of discharge measurements conducted using the pressure-time method.
文摘The paper presents selected experience of the authors resulting from the optimization tests of double-regulated water turbines. Among the methods for measuring the discharge through the turbine used in such tests, particular attention was paid to index methods allowing to measure the relative discharge through the turbine-the index current meter method and the methods based on measuring the differential pressure between two points properly located at the turbine flow system (i.e., Winter-Kennedy method). These methods contribute to effective reduction of the cost of optimizing the turbine that is extremely important for small hydropower plants regarding installed capacity. The paper presents selected examples of the optimization tests and experiences that arise from these tests.
文摘Squeezing flow of nanofluids has been taken into account under the effects of viscous dissipation and velocity slip.Two types of base fluids are used to study the behavior of Copper nanoparticles between parallel plates.Nonlinear ordinary differential equations governing the flow are obtained by imposing similarity transformations on conservation laws.Resulting equations are solved by using an efficient analytical technique the variation of parameters method(VPM).Influences of nanoparticle concentration and different emerging parameters on flow profiles are presented graphically coupled with comprehensive discussions.A numerical solution is also sought for the sake of comparison.Effect of different parameters on skin friction coefficient and Nusselt number is also discussed.