The main function of a hot blast stove is to deliver a high-temperature and stable hot blast to the blast furnace,which has an important impact on the blast furnace ironmaking process.To improve the combustion efficie...The main function of a hot blast stove is to deliver a high-temperature and stable hot blast to the blast furnace,which has an important impact on the blast furnace ironmaking process.To improve the combustion efficiency,a simulation model of the combustion part of an internal combustion hot blast stove was established by combining turbulence,combustion,and radiation models.Based on the original model,a new type of internal combustion hot blast stove is proposed.The results indicated insufficient combustion in the original structure and higher CO concentrations in the corners of the eyes at both ends of the combustor outlet,the recirculation area at the bottom of the combustion chamber was mainly concentrated in the middle part.With the new structure of the hot blast stove,the gas baffles with different inclination angles are added to the rectangular burner,at the outlet of the combustion chamber,the CO concentration is reduced to a certain extent,and the temperature distribution is more uniform.When the inclination angle of the gas baffle is 60°,the combustion chamber outlet section average temperature rises from 1686 K to 1693 K,the outlet flue gas average volume fraction of CO decreases the most,and the average volume fraction of CO decreases from 0.00708%to 0.00568%,which could reduce the CO content by about 20%.展开更多
Single crystal silicon freestanding structures for tensile and fatigue testing were treated with KrF excimer laser to improve surface roughness and accordingly mechanical performance. Sample thickness was 5 μm. Local...Single crystal silicon freestanding structures for tensile and fatigue testing were treated with KrF excimer laser to improve surface roughness and accordingly mechanical performance. Sample thickness was 5 μm. Localized laser treatment was successful in eliminating the scallops developed during Bosch process and in reducing surface roughness. Harsh irradiation at laser energies up to 4 J/cm2 was only possible due to localized treatment without significant vibrations occurring on the freestanding samples that led to fracture in preliminary experiments at energies as low as 0.16 J/cm2. Finite element analysis was used to investigate the temperature distribution on the irradiated structures. Atomic force microscopy (AFM) and Raman spectroscopy were also used to assess surface roughness, crystallinity changes and surface stresses developing on surfaces subjected to perpendicular laser irradiation. At a high energy (3.2 J/cm2) the top surface showed a decrease of roughness compared to fabricated samples. Raman spectroscopy showed the dominance of crystalline silicon after laser irradiation. The effects of laser energy, number of展开更多
The swine industry in China is a thriving and evolving industry that has shown phenomenal growth over the past 10 years. To insure long term success and viability in a worldwide competitive industry such as pork, ther...The swine industry in China is a thriving and evolving industry that has shown phenomenal growth over the past 10 years. To insure long term success and viability in a worldwide competitive industry such as pork, there is need for a National Swine Genetic Improvement Program. This program needs to draw on expertise and technology from across the world for its development, but it should be based on the structure of the pig industry in China and be led by Chinese scientists, administrators and producers. National Genetic Improvement requires more than just technology. A successful program of national genetic improvement will require cooperation from the industry and the government. The support for the university system is essential for the success of the pig industry. The university system has a vital role on education (of students, faculty, producers and consumers) as well as research and technology transfer. The government could also have a role in supporting the central test stations and AI stations across the country. An accurate and comprehensive pedigree maintenance system is essential to genetic improvement. And it will be vitally important to be active in the importation of new genetics to sample other populations.展开更多
Nickel metal hydride battery in bipolar design offers some advantages for its application as a power storage system for electric and hybrid vehicles. This paper deals with the structure design and electrochemical stud...Nickel metal hydride battery in bipolar design offers some advantages for its application as a power storage system for electric and hybrid vehicles. This paper deals with the structure design and electrochemical studies of bipolar Ni/MH batteries for hybrid vehicles. An improvement is applied in bipolar battery design, and such bipolar Ni/MH batteries with 5 sub-cells have been assembled and investigated. Testing results show that bipolar batteries with improved structure have better compression tolerance and cycle performance than conventional ones. In addition, the improved bipolar batteries display excellent large current discharge ability and high power density. As simulating working conditions for hybrid vehicles, the batteries show good stability during pulse cycles, which verifies the possibility of being used as a power storage device on hybrid vehicles.展开更多
In this paper, a new pressure reducing valve （PRV） with an orifice plate is proposed. The main objective is to explain the mechanisms of pressure reduction and energy conversion in the new PRV. A numerical simulatio...In this paper, a new pressure reducing valve （PRV） with an orifice plate is proposed. The main objective is to explain the mechanisms of pressure reduction and energy conversion in the new PRV. A numerical simulation method was used to investigate the PRV internal flow field and to analyze the throttling effects of the orifice plate and the transform of thermal parameters as outlet pressure, outlet temperature, velocity, and superheat. A structure improvement method for the valve body and orifice plate is put forward to reduce energy loss. The governing equations for internal flow numerical simulation are composed of the continuity, momentum, energy and k-e transport equations, based on isotropic eddy viscosity theory. Different valve plug displacement models were built to describe the double throttling process. Our analysis shows that the steam pressure drops twice and the degree of superheat increases. There are also lots of eddies which clog the flow channel and disturb the steam flow in the valve cavity after the valve plug and the outlet cavity. After modifying the structure, the numerical results show a better performance of steam flow.展开更多
Hydraulic equipment is widely applied in the fields of engineering construction, manufacture and mining. As the core component of hydraulic equipment, hydraulic cylinder will directly affect the whole operation of hyd...Hydraulic equipment is widely applied in the fields of engineering construction, manufacture and mining. As the core component of hydraulic equipment, hydraulic cylinder will directly affect the whole operation of hydraulic equipment. This paper will analyze the improvement of hydraulic cylinder structure and expect to enhance its reliability and stability.展开更多
The design quality of construction drawing of building structure is an important basis of engineering construction quality, which can fully reflect the design concept. Any problems existing in the design of constructi...The design quality of construction drawing of building structure is an important basis of engineering construction quality, which can fully reflect the design concept. Any problems existing in the design of construction drawing will affect the safety of building. At the same time, the design of construction drawing has certain technical content, which reflects the architects grasp of the scheme and the ability to apply technology. Therefore, in order to conscientiously implement the relevant regulations of national architectural design and improve the design quality of structural construction drawings, this paper analyzes the problems existing in the design of structural construction drawings of architectural engineering, and puts forward some improvement suggestions for reference by structural construction drawing designers.展开更多
Building high-performance aerogels with biomass-derived rather than fossil-derived polymers is an eco-friendlier option given the increasingly serious sustainability issues.Chitosan(CS)aero-gels with oriented pore str...Building high-performance aerogels with biomass-derived rather than fossil-derived polymers is an eco-friendlier option given the increasingly serious sustainability issues.Chitosan(CS)aero-gels with oriented pore structures exhibit broad application prospects owing to light weight,high porosity,and favorable bioactivity,but the dominating drawback in low mechanical strength greatly hinders their functional advantages.In this study,two types of silk microfibers with simi-lar diameter yet different aspect ratios(1-3(denoting as SmSF)and 50-100(denoting as LmSF))were used as fillers to reinforce CS aerogels prepared by directional freeze casting.The distinc-tion of SmSF and LmSF in size led to their notable variations in distribution pattern,as SmSF embedded within the individual CS lamellae while LmSF traversed throughout the adjacent CS lamellae,which in consequence significantly influence their mechanical reinforcing efficiency.The compressive strength values could be improved from 61.67 kPa(pure CS aerogel)to 82.13 kPa(SmSF/CS aerogel)and 165.03 kPa(LmSF/CS aerogel),respectively,attributing to the tran-sition in deformation mechanisms from a bending-to crumpling-dominated mode.In addition,the embedding or bridging structure could also change the liquid transportation property of CS aerogels.The results of this study demonstrated the feasibility of applying filler-size-mediated strategy for material structural optimization.展开更多
Transportation structures such as composite pavements and railway foundations typically consist of multi-layered media designed to withstand high bearing capacity.A theoretical understanding of load transfer mechanism...Transportation structures such as composite pavements and railway foundations typically consist of multi-layered media designed to withstand high bearing capacity.A theoretical understanding of load transfer mechanisms in these multi-layer composites is essential,as it offers intuitive insights into parametric influences and facilitates enhanced structural performance.This paper employs an improved transfer matrix method to address the limitations of existing theoretical approaches for analyzing multi-layer composite structures.By establishing a twodimensional composite pavement model,it investigates load transfer characteristics and validates the accuracy through finite element simulation.The proposed method offers a straightforward analytical approach for examining internal interactions between structural layers.Case studies indicate that the concrete surface layer is the main load-bearing layer for most vertical normal and shear stresses.The soil base layer reduces the overall mechanical response of the substructure,while horizontal actions increase the risk of interfacial slip and cracking.Structural optimization analysis demonstrates that increasing the thickness of the concrete surface layer,enhancing the thickness and stiffness of the soil base layer,or incorporating gradient layers can significantly mitigate these risks of interfacial slip and cracking.The findings of this study can guide the optimization design,parameter analysis,and damage prevention of multi-layer composite structures.展开更多
The traditional large electroslag remelting furnaces have many shortages,such as high short-network impedance and inductance,long maintenance time for electrode replacement,low stiffness of driveline,and low control a...The traditional large electroslag remelting furnaces have many shortages,such as high short-network impedance and inductance,long maintenance time for electrode replacement,low stiffness of driveline,and low control accuracy of remelting speed.The present research was aimed to solve these problems through structure modification and constant remelting speed control for a 120-t electroslag remelting(ESR) furnace.Based on the technique of three-phase double electrodes in series,the short-network system and the structure of the 120-t ESR furnace were improved;and a continuous feeding system for the self-consumption electrode was proposed.A selfdesigned fully hydraulic driveline system with three degrees of freedom was successfully applied to the 120-t ESR furnace.An electrode auto-replacement system and the S-style speed-control curve of electrode-feeding system were designed on the basis of the soft measurement/sensing model on the remaining electrode length so as to obtain a high accuracy control system for constant remelting speed.The experiment products showed good surface quality and cross-sectional results,indicating good system control,and verifying the effectiveness of the structure modification of the furnace.展开更多
The dynamic characteristics of a single liquid-filled pipe have been broadly studied in the previous literature.The parallel liquid-filled pipe(PLFP)system is also widely used in engineering,and its structure is more ...The dynamic characteristics of a single liquid-filled pipe have been broadly studied in the previous literature.The parallel liquid-filled pipe(PLFP)system is also widely used in engineering,and its structure is more complex than that of a single pipe.However,there are few reports about the dynamic characteristics of the PLFPs.Therefore,this paper proposes improved frequency modeling and solution for the PLFPs,involving the logical alignment principle and coupled matrix processing.The established model incorporates both the fluid-structure interaction(FSI)and the structural coupling of the PLFPs.The validity of the established model is verified by modal experiments.The effects of some unique parameters on the dynamic characteristics of the PLFPs are discussed.This work provides a feasible method for solving the FSI of multiple pipes in parallel and potential theoretical guidance for the dynamic analysis of the PLFPs in engineering.展开更多
To compensate for the imperfection of traditional bi-directional evolutionary structural optimization, material interpolation scheme and sensitivity filter functions are introduced. A suitable filter can overcome the ...To compensate for the imperfection of traditional bi-directional evolutionary structural optimization, material interpolation scheme and sensitivity filter functions are introduced. A suitable filter can overcome the checkerboard and mesh-dependency. And the historical information on accurate elemental sensitivity numbers are used to keep the objective function converging steadily. Apart from rational intervals of the relevant important parameters, the concept of distinguishing between active and non-active elements design is proposed, which can be widely used for improving the function and artistry of structures directly, especially for a one whose accurate size is not given. Furthermore, user-friendly software packages are developed to enhance its accessibility for practicing engineers and architects. And to reduce the time cost for large timeconsuming complex structure optimization, parallel computing is built-in in the MATLAB codes. The program is easy to use for engineers who may not be familiar with either FEA or structure optimization. And developers can make a deep research on the algorithm by changing the MATLAB codes. Several classical examples are given to show that the improved BESO method is superior for its handy and utility computer program software.展开更多
Over the past seven decades since the founding of the People’s Republic of China in 1949,China has continuously increased its import and export volumes along with improving its trade structure,becoming a major tradin...Over the past seven decades since the founding of the People’s Republic of China in 1949,China has continuously increased its import and export volumes along with improving its trade structure,becoming a major trading nation and making progress toward a trading power.In the 13th Five-Year Plan period(2016-2020),China has experienced acceleration in its foreign trade structural adjustment under its opening-up strategy,and the function of foreign trade has shifted from being a driver for growth to being a way to balance development.China is expected to continue its trade growth momentum and structural improvement and strengthen its trade competitiveness.In achieving this vision,China should make efforts to increase structural equilibrium,create a favorable external trade environment,and pave the way for trade growth and sustainable development.展开更多
Ever since involvement of the Binhai New Area into the national development strategy, carrying out highly effective financing promptly will play the pivotal role to implement its economic development strategy smoothly...Ever since involvement of the Binhai New Area into the national development strategy, carrying out highly effective financing promptly will play the pivotal role to implement its economic development strategy smoothly. In this paper, based on nature of regional financing, the descriptive analysis for the financing condition of the Binhai New Area is carried on. And also based on financing restraint theory and the neoclassic investment model, a real diagnosis analysis for the financing constraint condition of the Binhai New Area is studied. Finally, the existed questions in it are pointed out, and propose the correlative improvement countermeasure is put forward.展开更多
There is a global trend for seismic response improvement of new buildings to reduce cost and future damage. It is also important to improve existing structures that are designed without consideration of seismic load o...There is a global trend for seismic response improvement of new buildings to reduce cost and future damage. It is also important to improve existing structures that are designed without consideration of seismic load or using old provisions that cannot meet the new one. The objective of this paper is to draw attention to evaluate existing reinforced concrete school buildings, then to present a proposed methodology to improve the behaviour of such schools with low cost especially in a developing country. The proposed method uses overhead water tanks as a tuned mass damper. A pushover analysis has been performed to evaluate the existing schools and perform a feasibility study to select the best solution to achieve seismic response improvement of the existing structure. Of course, the proposed methodology can be applied easily to other existing structures.展开更多
Rapid alternating stress is formed in structure subjected to harsh thermal-acoustic loads,which will affect fatigue performance and reduce fatigue life seriously.First,fatigue experiment of superalloy thin-walled stru...Rapid alternating stress is formed in structure subjected to harsh thermal-acoustic loads,which will affect fatigue performance and reduce fatigue life seriously.First,fatigue experiment of superalloy thin-walled structure was carried out to obtain fatigue damage location and failure time of the experiment specimen,and S-iN curves of superalloy thin-walled structure at 723 K were fitted.Then,dynamic response simulation of superalloy thin-walled structure under the same load as experiment was implemented,and fatigue life was estimated based on the fatigue life prediction model which mainly included:improved rain-flow counting method,Morrow average stress model and Miner linear cumulative damage theory.Further,comparisons between simulation solutions and experimental results achieved a consistency,which verified the validity of the Fatigue Life Prediction Model(FLPM).Moreover,taking a rectangle plate as the analysis object,the distributions of Fain-low circulation blocks and damage levels of the structure were discussed respectively.Finally,current research indicates that in pre-buckling the structure is in softened area and fatigue life decreases with the increase of temperature;in post-buckling the structure is in hardened area and fatigue life increases with the increase of temperature within a certain range.展开更多
DC-inverter split air-conditioner is widely used in Chinese homes as a result of its high-efficiency and energy-saving. Recently, the researches on its outdoor unit have focused on the influence of surrounding structu...DC-inverter split air-conditioner is widely used in Chinese homes as a result of its high-efficiency and energy-saving. Recently, the researches on its outdoor unit have focused on the influence of surrounding structures upon the aerodynamic and acoustic performance, however they are only limited to the influence of a few parameters on the performance, and practical design of the unit requires more detailed parametric analysis. Three-dimensional computational fluid dynamics（CFD） and computational aerodynamic acoustics（CAA） simulation based on FLUENT solver is used to study the influence of surrounding structures upon the aforementioned properties of the unit. The flow rate and sound pressure level are predicted for different rotating speed, and agree well with the experimental results. The parametric influence of three main surrounding structures（i.e. the heat sink, the bell-mouth type shroud and the outlet grille） upon the aerodynamic performance of the unit is analyzed thoroughly. The results demonstrate that the tip vortex plays a major role in the flow fields near the blade tip and has a great effect on the flow field of the unit. The inlet ring＇s size and throat＇s depth of the bell-mouth type shroud, and the through-flow area and configuration of upwind and downwind sections of the outlet grille are the most important factors that affect the aerodynamic performance of the unit. Furthermore, two improved schemes against the existing prototype of the unit are developed, which both can significantly increase the flow rate more than 6 %（i.e. 100 m3·h～（-1）） at given rotating speeds. The inevitable increase of flow noise level when flow rate is increased and the advantage of keeping a lower rotating speed are also discussed. The presented work could be a useful guideline in designing the aerodynamic and acoustic performance of the split air-conditioner in engineering practice.展开更多
Based on the growth mechanism of natural biological branching systems and inspiration from the morphology of plant root tips,a bionic design method called Improved Adaptive Growth Method(IAGM)has been proposed in the ...Based on the growth mechanism of natural biological branching systems and inspiration from the morphology of plant root tips,a bionic design method called Improved Adaptive Growth Method(IAGM)has been proposed in the authors’previous research and successfully applied to the reinforcement optimization of three-dimensional box structures with respect to natural frequencies.However,as a kind of ground structure methods,the final layout patterns of stiffeners obtained by using the IAGM are highly subjected to their ground structures,which restricts the optimization effect and freedom to further improve the dynamic performance of structures.To solve this problem,a novel post-processing geometry and size optimization approach is proposed in this article.This method takes the former layout optimization result as start,and iteratively finds the optimal layout angles,locations,and lengths of stiffeners with a few design variables by optimizing the positions of some specific node lines called active node lines.At the same time,thick-nesses of stiffeners are also optimized to further improve natural frequencies of three-dimensional box structures.Using this method,stiffeners can be successfully separated from their ground structures and further effectively improve natural frequencies of three-dimensional box structures with less material consumption.Typical numerical examples are illustrated to validate the effectiveness and advantages of the suggested method.展开更多
Starch with different particle sizes has different compositions and different physical and chemical properties.The amylopectin content and protein content and lipid content of small granule B starch are higher than th...Starch with different particle sizes has different compositions and different physical and chemical properties.The amylopectin content and protein content and lipid content of small granule B starch are higher than that of A-type starch,which can form spiral complex to limit the expansion of starch.Under the same treatment conditions,B-type starch is more vulnerable to damage,sensitive to freezing storage,even breaks in freezing storage,and has higher gelatinization temperature than other starch during freezing.Amylose contained in A-type has high content,high crystallinity,high degree of ordering after frozen storage and insensitivity to frozen storage,which is beneficial to improve the stability of pores and texture of frozen dough.With the extension of freezing time,the content of amylose decreased,while the content of various amylopectin increased and the conformation of polysaccharide changed.Starch deterioration is different under different frozen storage conditions.The deterioration mechanism of frozen dough can be evaluated by variety of starch characteristics during freezing process,which is of great guiding significance to the improvement of frozen dough technology.展开更多
Accurately solving transient nonlinear inverse heat conduction problems in complex structures is of great importance to provide key parameters for modeling coupled heat transfer process and the structure’s optimizati...Accurately solving transient nonlinear inverse heat conduction problems in complex structures is of great importance to provide key parameters for modeling coupled heat transfer process and the structure’s optimization design.The finite element method in ABAQUS is employed to solve the direct transient nonlinear heat conduction problem.Improved particle swarm optimization(PSO)method is developed and used to solve the transient nonlinear inverse problem.To investigate the inverse performances,some numerical tests are provided.Boundary conditions at inaccessible surfaces of a scramjet combustor with the regenerative cooling system are inversely identified.The results show that the new methodology can accurately and efficiently determine the boundary conditions in the scramjet combustor with the regenerative cooling system.By solving the transient nonlinear inverse problem,the improved particle swarm optimization for solving the transient nonlinear inverse heat conduction problem in a complex structure is verified.展开更多
文摘The main function of a hot blast stove is to deliver a high-temperature and stable hot blast to the blast furnace,which has an important impact on the blast furnace ironmaking process.To improve the combustion efficiency,a simulation model of the combustion part of an internal combustion hot blast stove was established by combining turbulence,combustion,and radiation models.Based on the original model,a new type of internal combustion hot blast stove is proposed.The results indicated insufficient combustion in the original structure and higher CO concentrations in the corners of the eyes at both ends of the combustor outlet,the recirculation area at the bottom of the combustion chamber was mainly concentrated in the middle part.With the new structure of the hot blast stove,the gas baffles with different inclination angles are added to the rectangular burner,at the outlet of the combustion chamber,the CO concentration is reduced to a certain extent,and the temperature distribution is more uniform.When the inclination angle of the gas baffle is 60°,the combustion chamber outlet section average temperature rises from 1686 K to 1693 K,the outlet flue gas average volume fraction of CO decreases the most,and the average volume fraction of CO decreases from 0.00708%to 0.00568%,which could reduce the CO content by about 20%.
文摘Single crystal silicon freestanding structures for tensile and fatigue testing were treated with KrF excimer laser to improve surface roughness and accordingly mechanical performance. Sample thickness was 5 μm. Localized laser treatment was successful in eliminating the scallops developed during Bosch process and in reducing surface roughness. Harsh irradiation at laser energies up to 4 J/cm2 was only possible due to localized treatment without significant vibrations occurring on the freestanding samples that led to fracture in preliminary experiments at energies as low as 0.16 J/cm2. Finite element analysis was used to investigate the temperature distribution on the irradiated structures. Atomic force microscopy (AFM) and Raman spectroscopy were also used to assess surface roughness, crystallinity changes and surface stresses developing on surfaces subjected to perpendicular laser irradiation. At a high energy (3.2 J/cm2) the top surface showed a decrease of roughness compared to fabricated samples. Raman spectroscopy showed the dominance of crystalline silicon after laser irradiation. The effects of laser energy, number of
文摘The swine industry in China is a thriving and evolving industry that has shown phenomenal growth over the past 10 years. To insure long term success and viability in a worldwide competitive industry such as pork, there is need for a National Swine Genetic Improvement Program. This program needs to draw on expertise and technology from across the world for its development, but it should be based on the structure of the pig industry in China and be led by Chinese scientists, administrators and producers. National Genetic Improvement requires more than just technology. A successful program of national genetic improvement will require cooperation from the industry and the government. The support for the university system is essential for the success of the pig industry. The university system has a vital role on education (of students, faculty, producers and consumers) as well as research and technology transfer. The government could also have a role in supporting the central test stations and AI stations across the country. An accurate and comprehensive pedigree maintenance system is essential to genetic improvement. And it will be vitally important to be active in the importation of new genetics to sample other populations.
文摘Nickel metal hydride battery in bipolar design offers some advantages for its application as a power storage system for electric and hybrid vehicles. This paper deals with the structure design and electrochemical studies of bipolar Ni/MH batteries for hybrid vehicles. An improvement is applied in bipolar battery design, and such bipolar Ni/MH batteries with 5 sub-cells have been assembled and investigated. Testing results show that bipolar batteries with improved structure have better compression tolerance and cycle performance than conventional ones. In addition, the improved bipolar batteries display excellent large current discharge ability and high power density. As simulating working conditions for hybrid vehicles, the batteries show good stability during pulse cycles, which verifies the possibility of being used as a power storage device on hybrid vehicles.
基金Project (No. 2012C11018-1) supported by the Science and Technology Department of Zhejiang Province,China
文摘In this paper, a new pressure reducing valve （PRV） with an orifice plate is proposed. The main objective is to explain the mechanisms of pressure reduction and energy conversion in the new PRV. A numerical simulation method was used to investigate the PRV internal flow field and to analyze the throttling effects of the orifice plate and the transform of thermal parameters as outlet pressure, outlet temperature, velocity, and superheat. A structure improvement method for the valve body and orifice plate is put forward to reduce energy loss. The governing equations for internal flow numerical simulation are composed of the continuity, momentum, energy and k-e transport equations, based on isotropic eddy viscosity theory. Different valve plug displacement models were built to describe the double throttling process. Our analysis shows that the steam pressure drops twice and the degree of superheat increases. There are also lots of eddies which clog the flow channel and disturb the steam flow in the valve cavity after the valve plug and the outlet cavity. After modifying the structure, the numerical results show a better performance of steam flow.
文摘Hydraulic equipment is widely applied in the fields of engineering construction, manufacture and mining. As the core component of hydraulic equipment, hydraulic cylinder will directly affect the whole operation of hydraulic equipment. This paper will analyze the improvement of hydraulic cylinder structure and expect to enhance its reliability and stability.
文摘The design quality of construction drawing of building structure is an important basis of engineering construction quality, which can fully reflect the design concept. Any problems existing in the design of construction drawing will affect the safety of building. At the same time, the design of construction drawing has certain technical content, which reflects the architects grasp of the scheme and the ability to apply technology. Therefore, in order to conscientiously implement the relevant regulations of national architectural design and improve the design quality of structural construction drawings, this paper analyzes the problems existing in the design of structural construction drawings of architectural engineering, and puts forward some improvement suggestions for reference by structural construction drawing designers.
基金supported by National Natural Science Foundation of China(No.52103149)State of Sericulture Industry Tech-nology System(No.CARS-18-ZJ0501)+2 种基金Zhejiang Provincial Science and Technology Plans(No.2021C02072-6)China Postdoctoral Science Foundation(No.2023M743064)Zhejiang University Start-up Fund.
文摘Building high-performance aerogels with biomass-derived rather than fossil-derived polymers is an eco-friendlier option given the increasingly serious sustainability issues.Chitosan(CS)aero-gels with oriented pore structures exhibit broad application prospects owing to light weight,high porosity,and favorable bioactivity,but the dominating drawback in low mechanical strength greatly hinders their functional advantages.In this study,two types of silk microfibers with simi-lar diameter yet different aspect ratios(1-3(denoting as SmSF)and 50-100(denoting as LmSF))were used as fillers to reinforce CS aerogels prepared by directional freeze casting.The distinc-tion of SmSF and LmSF in size led to their notable variations in distribution pattern,as SmSF embedded within the individual CS lamellae while LmSF traversed throughout the adjacent CS lamellae,which in consequence significantly influence their mechanical reinforcing efficiency.The compressive strength values could be improved from 61.67 kPa(pure CS aerogel)to 82.13 kPa(SmSF/CS aerogel)and 165.03 kPa(LmSF/CS aerogel),respectively,attributing to the tran-sition in deformation mechanisms from a bending-to crumpling-dominated mode.In addition,the embedding or bridging structure could also change the liquid transportation property of CS aerogels.The results of this study demonstrated the feasibility of applying filler-size-mediated strategy for material structural optimization.
基金supported by Fundamental Research Funds for the Central Universities(No.lzujbky-2024-05)Innovation Foundation of Provincial Education Department of Gansu(2024B-005)+2 种基金Scientific Department of Gansu(24CXGA083,24CXGA024,JK2024-28,JK2024-32 and 23CXJA0007)Industrial Support Plan Project of Provincial Education Department of Gansu(2025CYZC-003 and CYZC-2024-10)the Hunan Natural Science Foundation Science and Education Joint Fund Project(2022JJ60109).
文摘Transportation structures such as composite pavements and railway foundations typically consist of multi-layered media designed to withstand high bearing capacity.A theoretical understanding of load transfer mechanisms in these multi-layer composites is essential,as it offers intuitive insights into parametric influences and facilitates enhanced structural performance.This paper employs an improved transfer matrix method to address the limitations of existing theoretical approaches for analyzing multi-layer composite structures.By establishing a twodimensional composite pavement model,it investigates load transfer characteristics and validates the accuracy through finite element simulation.The proposed method offers a straightforward analytical approach for examining internal interactions between structural layers.Case studies indicate that the concrete surface layer is the main load-bearing layer for most vertical normal and shear stresses.The soil base layer reduces the overall mechanical response of the substructure,while horizontal actions increase the risk of interfacial slip and cracking.Structural optimization analysis demonstrates that increasing the thickness of the concrete surface layer,enhancing the thickness and stiffness of the soil base layer,or incorporating gradient layers can significantly mitigate these risks of interfacial slip and cracking.The findings of this study can guide the optimization design,parameter analysis,and damage prevention of multi-layer composite structures.
基金financially supported by the National Science and Technology Major Project of the Eleventh Five-Year Plan of China(2009ZX04006-032)
文摘The traditional large electroslag remelting furnaces have many shortages,such as high short-network impedance and inductance,long maintenance time for electrode replacement,low stiffness of driveline,and low control accuracy of remelting speed.The present research was aimed to solve these problems through structure modification and constant remelting speed control for a 120-t electroslag remelting(ESR) furnace.Based on the technique of three-phase double electrodes in series,the short-network system and the structure of the 120-t ESR furnace were improved;and a continuous feeding system for the self-consumption electrode was proposed.A selfdesigned fully hydraulic driveline system with three degrees of freedom was successfully applied to the 120-t ESR furnace.An electrode auto-replacement system and the S-style speed-control curve of electrode-feeding system were designed on the basis of the soft measurement/sensing model on the remaining electrode length so as to obtain a high accuracy control system for constant remelting speed.The experiment products showed good surface quality and cross-sectional results,indicating good system control,and verifying the effectiveness of the structure modification of the furnace.
基金Project supported by the National Natural Science Foundation of China(No.11972112)the Fundamental Research Funds for the Central Universities of China(Nos.N2103024 and N2103002)the Major Projects of Aero-Engines and Gasturbines(No.J2019-I-0008-0008)。
文摘The dynamic characteristics of a single liquid-filled pipe have been broadly studied in the previous literature.The parallel liquid-filled pipe(PLFP)system is also widely used in engineering,and its structure is more complex than that of a single pipe.However,there are few reports about the dynamic characteristics of the PLFPs.Therefore,this paper proposes improved frequency modeling and solution for the PLFPs,involving the logical alignment principle and coupled matrix processing.The established model incorporates both the fluid-structure interaction(FSI)and the structural coupling of the PLFPs.The validity of the established model is verified by modal experiments.The effects of some unique parameters on the dynamic characteristics of the PLFPs are discussed.This work provides a feasible method for solving the FSI of multiple pipes in parallel and potential theoretical guidance for the dynamic analysis of the PLFPs in engineering.
基金supported by the National Natural Science Foundation of China(No.51078311)
文摘To compensate for the imperfection of traditional bi-directional evolutionary structural optimization, material interpolation scheme and sensitivity filter functions are introduced. A suitable filter can overcome the checkerboard and mesh-dependency. And the historical information on accurate elemental sensitivity numbers are used to keep the objective function converging steadily. Apart from rational intervals of the relevant important parameters, the concept of distinguishing between active and non-active elements design is proposed, which can be widely used for improving the function and artistry of structures directly, especially for a one whose accurate size is not given. Furthermore, user-friendly software packages are developed to enhance its accessibility for practicing engineers and architects. And to reduce the time cost for large timeconsuming complex structure optimization, parallel computing is built-in in the MATLAB codes. The program is easy to use for engineers who may not be familiar with either FEA or structure optimization. And developers can make a deep research on the algorithm by changing the MATLAB codes. Several classical examples are given to show that the improved BESO method is superior for its handy and utility computer program software.
文摘Over the past seven decades since the founding of the People’s Republic of China in 1949,China has continuously increased its import and export volumes along with improving its trade structure,becoming a major trading nation and making progress toward a trading power.In the 13th Five-Year Plan period(2016-2020),China has experienced acceleration in its foreign trade structural adjustment under its opening-up strategy,and the function of foreign trade has shifted from being a driver for growth to being a way to balance development.China is expected to continue its trade growth momentum and structural improvement and strengthen its trade competitiveness.In achieving this vision,China should make efforts to increase structural equilibrium,create a favorable external trade environment,and pave the way for trade growth and sustainable development.
基金This paper is supported by the Philosophy and Social Science Foundation of Tianjin City （No. TJ05-GL010）, and supported by the Two Groups ＂Binhai New Area Development Study＂ and ＂Construction of Philosophy and Social Sciences＂ in Tianjin City, and also supported by Tianjin Scientific and Technologic Development Strategy.
文摘Ever since involvement of the Binhai New Area into the national development strategy, carrying out highly effective financing promptly will play the pivotal role to implement its economic development strategy smoothly. In this paper, based on nature of regional financing, the descriptive analysis for the financing condition of the Binhai New Area is carried on. And also based on financing restraint theory and the neoclassic investment model, a real diagnosis analysis for the financing constraint condition of the Binhai New Area is studied. Finally, the existed questions in it are pointed out, and propose the correlative improvement countermeasure is put forward.
文摘There is a global trend for seismic response improvement of new buildings to reduce cost and future damage. It is also important to improve existing structures that are designed without consideration of seismic load or using old provisions that cannot meet the new one. The objective of this paper is to draw attention to evaluate existing reinforced concrete school buildings, then to present a proposed methodology to improve the behaviour of such schools with low cost especially in a developing country. The proposed method uses overhead water tanks as a tuned mass damper. A pushover analysis has been performed to evaluate the existing schools and perform a feasibility study to select the best solution to achieve seismic response improvement of the existing structure. Of course, the proposed methodology can be applied easily to other existing structures.
基金co-supported by Aviation Basic Science Fund Project of China(No.20151554002)Natural Sciences Key Project of Chengdu Aeronautic Polytechnic in China(No.061754)Natural Sciences General Project of Sichuan Province Education Department in China(No.18ZB0057).
文摘Rapid alternating stress is formed in structure subjected to harsh thermal-acoustic loads,which will affect fatigue performance and reduce fatigue life seriously.First,fatigue experiment of superalloy thin-walled structure was carried out to obtain fatigue damage location and failure time of the experiment specimen,and S-iN curves of superalloy thin-walled structure at 723 K were fitted.Then,dynamic response simulation of superalloy thin-walled structure under the same load as experiment was implemented,and fatigue life was estimated based on the fatigue life prediction model which mainly included:improved rain-flow counting method,Morrow average stress model and Miner linear cumulative damage theory.Further,comparisons between simulation solutions and experimental results achieved a consistency,which verified the validity of the Fatigue Life Prediction Model(FLPM).Moreover,taking a rectangle plate as the analysis object,the distributions of Fain-low circulation blocks and damage levels of the structure were discussed respectively.Finally,current research indicates that in pre-buckling the structure is in softened area and fatigue life decreases with the increase of temperature;in post-buckling the structure is in hardened area and fatigue life increases with the increase of temperature within a certain range.
基金Supported by Program for Changjiang Scholars and Innovative Research Team in University,Ministry of Education of China(PCSIRT)
文摘DC-inverter split air-conditioner is widely used in Chinese homes as a result of its high-efficiency and energy-saving. Recently, the researches on its outdoor unit have focused on the influence of surrounding structures upon the aerodynamic and acoustic performance, however they are only limited to the influence of a few parameters on the performance, and practical design of the unit requires more detailed parametric analysis. Three-dimensional computational fluid dynamics（CFD） and computational aerodynamic acoustics（CAA） simulation based on FLUENT solver is used to study the influence of surrounding structures upon the aforementioned properties of the unit. The flow rate and sound pressure level are predicted for different rotating speed, and agree well with the experimental results. The parametric influence of three main surrounding structures（i.e. the heat sink, the bell-mouth type shroud and the outlet grille） upon the aerodynamic performance of the unit is analyzed thoroughly. The results demonstrate that the tip vortex plays a major role in the flow fields near the blade tip and has a great effect on the flow field of the unit. The inlet ring＇s size and throat＇s depth of the bell-mouth type shroud, and the through-flow area and configuration of upwind and downwind sections of the outlet grille are the most important factors that affect the aerodynamic performance of the unit. Furthermore, two improved schemes against the existing prototype of the unit are developed, which both can significantly increase the flow rate more than 6 %（i.e. 100 m3·h～（-1）） at given rotating speeds. The inevitable increase of flow noise level when flow rate is increased and the advantage of keeping a lower rotating speed are also discussed. The presented work could be a useful guideline in designing the aerodynamic and acoustic performance of the split air-conditioner in engineering practice.
基金supported by National Natural Science Foundation of China(Nos.51975380,52005377)China Postdoctoral Science Foundation(No.2020M681346)Japan Society for the Promotion of Science(No.JP21J13418)。
文摘Based on the growth mechanism of natural biological branching systems and inspiration from the morphology of plant root tips,a bionic design method called Improved Adaptive Growth Method(IAGM)has been proposed in the authors’previous research and successfully applied to the reinforcement optimization of three-dimensional box structures with respect to natural frequencies.However,as a kind of ground structure methods,the final layout patterns of stiffeners obtained by using the IAGM are highly subjected to their ground structures,which restricts the optimization effect and freedom to further improve the dynamic performance of structures.To solve this problem,a novel post-processing geometry and size optimization approach is proposed in this article.This method takes the former layout optimization result as start,and iteratively finds the optimal layout angles,locations,and lengths of stiffeners with a few design variables by optimizing the positions of some specific node lines called active node lines.At the same time,thick-nesses of stiffeners are also optimized to further improve natural frequencies of three-dimensional box structures.Using this method,stiffeners can be successfully separated from their ground structures and further effectively improve natural frequencies of three-dimensional box structures with less material consumption.Typical numerical examples are illustrated to validate the effectiveness and advantages of the suggested method.
基金supported by the Key scientific and technological project of Henan Province(No.202102110143)Talent Projects from Henan University of Technology(No.2018RCJH08)the Joint Foundations from the NSFC-Henan Province(No.U1604235)。
文摘Starch with different particle sizes has different compositions and different physical and chemical properties.The amylopectin content and protein content and lipid content of small granule B starch are higher than that of A-type starch,which can form spiral complex to limit the expansion of starch.Under the same treatment conditions,B-type starch is more vulnerable to damage,sensitive to freezing storage,even breaks in freezing storage,and has higher gelatinization temperature than other starch during freezing.Amylose contained in A-type has high content,high crystallinity,high degree of ordering after frozen storage and insensitivity to frozen storage,which is beneficial to improve the stability of pores and texture of frozen dough.With the extension of freezing time,the content of amylose decreased,while the content of various amylopectin increased and the conformation of polysaccharide changed.Starch deterioration is different under different frozen storage conditions.The deterioration mechanism of frozen dough can be evaluated by variety of starch characteristics during freezing process,which is of great guiding significance to the improvement of frozen dough technology.
基金supported by the National Natural Science Foundation of China(Nos.12172078,51576026)Fundamental Research Funds for the Central Universities in China(No.DUT21LK04)。
文摘Accurately solving transient nonlinear inverse heat conduction problems in complex structures is of great importance to provide key parameters for modeling coupled heat transfer process and the structure’s optimization design.The finite element method in ABAQUS is employed to solve the direct transient nonlinear heat conduction problem.Improved particle swarm optimization(PSO)method is developed and used to solve the transient nonlinear inverse problem.To investigate the inverse performances,some numerical tests are provided.Boundary conditions at inaccessible surfaces of a scramjet combustor with the regenerative cooling system are inversely identified.The results show that the new methodology can accurately and efficiently determine the boundary conditions in the scramjet combustor with the regenerative cooling system.By solving the transient nonlinear inverse problem,the improved particle swarm optimization for solving the transient nonlinear inverse heat conduction problem in a complex structure is verified.
