The problem of water supply from the public distribution network still poses very serious problems in many cities in developing countries. Intermittent water supply pushes some households to build underground reinforc...The problem of water supply from the public distribution network still poses very serious problems in many cities in developing countries. Intermittent water supply pushes some households to build underground reinforced concrete tanks for water storage to cope with unwanted water breaks. This study that relies on the results of a survey of households in some areas of the city of Brazzaville (Republic of Congo) aims to verify the importance that users attach to the quality of the works constructed. Indeed, the reliability of the tanks resulting in their impermeability to the external environment has a direct impact on the quality of stored water and therefore the use that is made of water daily. Five areas were selected because of their soil moisture. By 256 tanks identified, 143 are made of reinforced concrete and 113 in masonry. The coating materials used to seal the walls are preferably the earthenware tiles (64% of tanks), then the Sika cement (31%). Food painting (5%) is only rarely used. However, 66% of households are not assured of the potability of the water stored. A significant number of households (46%) think that the stored water could be contaminated with noxious substances seeping from the outside through the walls of the tanks. The issue of sealing of underground water tanks, especially in areas where the water table is shallow, seems concerned users.展开更多
Design of watertight subdivision inherently involves its optimization with the objective to increase the index ＂A＂ above its minimum required value. In view of a big popularity of probabilistic search methods such a...Design of watertight subdivision inherently involves its optimization with the objective to increase the index ＂A＂ above its minimum required value. In view of a big popularity of probabilistic search methods such as genetic algorithms, this task is intrinsically time consuming. Thus, even when an optimal subdivision layout （i.e. topology） is determined, it can be found that the optimal bulkhead positions can be a great challenge time-wise, often forcing designers to satisfy with suboptimal solutions. The fundamental reason why this happens is that the nature of the optimized function （e.g., index ＂A＂ as a function of bulkhead positions） is unknown and hence it has no effect upon the choice of optimization strategy, which therefore reflects subjective but not factual preferences. In this paper we study the nature of functional dependency between the subdivision index and bulkhead positions, as a simplest case, and indicate pertinent optimization strategies that consequently reduce the optimization time. In our study we use a cruise ship model to demonstrate the application results of our findings.展开更多
This paper summarizes suitable material models for creep and damage of concrete which are coupled with heat and moisture transfer.The fully coupled approach or the staggered coupling is assumed.Governing equations are...This paper summarizes suitable material models for creep and damage of concrete which are coupled with heat and moisture transfer.The fully coupled approach or the staggered coupling is assumed.Governing equations are spatially discretized by the finite element method and the temporal discretization is done by the generalized trapezoidal method.Systems of non-linear algebraic equations are solved by the Newton method.Development of an efficient and extensible computer code based on the C++programming language is described.Finally,successful analyses of two real engineering problems are described.展开更多
Advances in meticulous dural closure technique remain a great challenge for watertight dural closure in the aged society,because the cerebrospinal fluid(CSF)leakage after spinal surgery is often accompanied with the d...Advances in meticulous dural closure technique remain a great challenge for watertight dural closure in the aged society,because the cerebrospinal fluid(CSF)leakage after spinal surgery is often accompanied with the disgusting wound infection,meningitis and pseudomeningocele.Here,a tetra-poly(ethylene glycol)(PEG)-based hydrogel sealant is developed with collective advantages of facile operation,high safety,quick set time,easy injectability,favorable mechanical strength and powerful tissue adhesion for effective sutureless dural closure during the surgery procedure.Impressively,this tetra-PEG sealant can instantaneously adhere to the irregular tissue surfaces even in a liquid environment,and effectively prevent or block off the intraoperative CSF leakage for sutureless dural closure and dura regeneration.Together,this sutureless tetra-PEG adhesive can be utilized as a very promising alternative for high-efficient watertight dural closure of the clinical patients who incidentally or deliberately undergo the durotomy during the spinal surgery.展开更多
The grating eddy current displacement sensor (GECDS) for distance or position measurement used in watertight electronic calipers was described. The sensor relies on repetitive variation of inductance against displacem...The grating eddy current displacement sensor (GECDS) for distance or position measurement used in watertight electronic calipers was described. The sensor relies on repetitive variation of inductance against displacement caused by the change of coupling areas between moving coils and static reflectors. The investigations focused on setting up and utilizing a computer model of the 3D eddy current fields and geometry to analyze causes of the production of measurement blind areas, and to investigate effects of the sensor parameters, such as axial gap between coils and reflectors, reflector length and reflector width on characteristics of the sensor. Simulation results indicated that the sensor has the smallest nonlinearity error of 0.15%, which agrees well with the experimental results.展开更多
文摘The problem of water supply from the public distribution network still poses very serious problems in many cities in developing countries. Intermittent water supply pushes some households to build underground reinforced concrete tanks for water storage to cope with unwanted water breaks. This study that relies on the results of a survey of households in some areas of the city of Brazzaville (Republic of Congo) aims to verify the importance that users attach to the quality of the works constructed. Indeed, the reliability of the tanks resulting in their impermeability to the external environment has a direct impact on the quality of stored water and therefore the use that is made of water daily. Five areas were selected because of their soil moisture. By 256 tanks identified, 143 are made of reinforced concrete and 113 in masonry. The coating materials used to seal the walls are preferably the earthenware tiles (64% of tanks), then the Sika cement (31%). Food painting (5%) is only rarely used. However, 66% of households are not assured of the potability of the water stored. A significant number of households (46%) think that the stored water could be contaminated with noxious substances seeping from the outside through the walls of the tanks. The issue of sealing of underground water tanks, especially in areas where the water table is shallow, seems concerned users.
文摘Design of watertight subdivision inherently involves its optimization with the objective to increase the index ＂A＂ above its minimum required value. In view of a big popularity of probabilistic search methods such as genetic algorithms, this task is intrinsically time consuming. Thus, even when an optimal subdivision layout （i.e. topology） is determined, it can be found that the optimal bulkhead positions can be a great challenge time-wise, often forcing designers to satisfy with suboptimal solutions. The fundamental reason why this happens is that the nature of the optimized function （e.g., index ＂A＂ as a function of bulkhead positions） is unknown and hence it has no effect upon the choice of optimization strategy, which therefore reflects subjective but not factual preferences. In this paper we study the nature of functional dependency between the subdivision index and bulkhead positions, as a simplest case, and indicate pertinent optimization strategies that consequently reduce the optimization time. In our study we use a cruise ship model to demonstrate the application results of our findings.
基金Financial support for this work was provided by the Czech Science Foundation,projects n.103/08/1119 and 105/10/1682support was provided by the Ministry of Education,Youth and Sports of the Czech Republic,project No.1M0579.
文摘This paper summarizes suitable material models for creep and damage of concrete which are coupled with heat and moisture transfer.The fully coupled approach or the staggered coupling is assumed.Governing equations are spatially discretized by the finite element method and the temporal discretization is done by the generalized trapezoidal method.Systems of non-linear algebraic equations are solved by the Newton method.Development of an efficient and extensible computer code based on the C++programming language is described.Finally,successful analyses of two real engineering problems are described.
基金supported by the Ministry of Science and Technology of the People’s Republic of China(2018YFE0104200)National Natural Science Foundation of China(51873214,51973226,81871782 and 82002030)the Youth Innovation Promotion Association CAS(No.2019031)for financial support.
文摘Advances in meticulous dural closure technique remain a great challenge for watertight dural closure in the aged society,because the cerebrospinal fluid(CSF)leakage after spinal surgery is often accompanied with the disgusting wound infection,meningitis and pseudomeningocele.Here,a tetra-poly(ethylene glycol)(PEG)-based hydrogel sealant is developed with collective advantages of facile operation,high safety,quick set time,easy injectability,favorable mechanical strength and powerful tissue adhesion for effective sutureless dural closure during the surgery procedure.Impressively,this tetra-PEG sealant can instantaneously adhere to the irregular tissue surfaces even in a liquid environment,and effectively prevent or block off the intraoperative CSF leakage for sutureless dural closure and dura regeneration.Together,this sutureless tetra-PEG adhesive can be utilized as a very promising alternative for high-efficient watertight dural closure of the clinical patients who incidentally or deliberately undergo the durotomy during the spinal surgery.
文摘The grating eddy current displacement sensor (GECDS) for distance or position measurement used in watertight electronic calipers was described. The sensor relies on repetitive variation of inductance against displacement caused by the change of coupling areas between moving coils and static reflectors. The investigations focused on setting up and utilizing a computer model of the 3D eddy current fields and geometry to analyze causes of the production of measurement blind areas, and to investigate effects of the sensor parameters, such as axial gap between coils and reflectors, reflector length and reflector width on characteristics of the sensor. Simulation results indicated that the sensor has the smallest nonlinearity error of 0.15%, which agrees well with the experimental results.
