The use of three-dimensional maps is more effective than two-dimensional maps in representing the Earth’s surface. However, the traditional methods used to create digital surface models are not efficient for capturin...The use of three-dimensional maps is more effective than two-dimensional maps in representing the Earth’s surface. However, the traditional methods used to create digital surface models are not efficient for capturing the details of Earth’s features. This is because they represent only three-dimensional objects in a single texture and do not provide a realistic representation of the real world. Additionally, there is a growing demand for up-to-date and accurate geo-information, particularly in urban areas. To address this challenge, a new technique is proposed in this study that involves integrating remote sensing, Geographic Information System, and Architecture Environment software to generate a highly-detailed three-dimensional model. The method described in this study includes several steps such as acquiring high-resolution satellite imagery, gathering ground truth data, performing radiometric and geometric corrections during image preprocessing, producing a 2D map of the region of interest, constructing a digital surface model by extending the building outlines, and transforming the model into multi-patch layers to create a 3D model for each object individually. The research findings indicate that the digital surface model obtained with comprehensive information is suitable for different purposes, such as environmental research, urban development and expansion planning, and shape recognition tasks.展开更多
In the framework of this research, the principle focus is to analyze the effects of fluid Prandtl number (Pr) on natural convection heat transfer in a volumetrically heated molten pool. As a part of the work, numerica...In the framework of this research, the principle focus is to analyze the effects of fluid Prandtl number (Pr) on natural convection heat transfer in a volumetrically heated molten pool. As a part of the work, numerical analysis is performed for hemispherical 3-D vessel slice to investigate the physics of the effect of Pr number on convective heat transfer characteristics in the melt pool. The investigation is based on ANSYS FLUET, where natural convection heat transfer effect is taken into consideration by Phase-change Effective Convectivity Model (PECM), which is implemented with FLUENT CFD as User Defined Function (UDF), programed by the user. The PECM is tested first by a benchmark test against CFD to gain confidence in its applicability as an analysis tool. Different simulant materials are used with their thermo-physical properties representing different Pr number as input for modelling for both single and double layer melt pool configuration. The selected modelling approach is validated against RASPLAV experimental result with respect to the inner temperature distribution that qualifies our model to run in the proceeding calculation. It is ensured that an isothermal boundary condition (343 K) is applied along vessel outer wall throughout the series of simulation cases. The corresponding Rayleigh number (Ra) ranges from 1014 - 1015 and Prandtl number (Pr) 3 - 5. It is found that the fluid Pr number has small effects on the averaged Nu numbers in the convection-dominated regions. The decrease in the Pr number may cause a decrease in the Nu numbers on the top and sidewalls of cavities. In the conduction dominated regions (stably stratified bottom parts of enclosure), the effect of fluid Pr number on heat transfer is more significant and it grows with increasing Ra number.展开更多
Statistical analysis of the entrance and wall dynamics of a high-flux gas-solid riser was done using solid concentration time series data collected from a 76 mm internal diameter and 10 m high riser of a CFB system wi...Statistical analysis of the entrance and wall dynamics of a high-flux gas-solid riser was done using solid concentration time series data collected from a 76 mm internal diameter and 10 m high riser of a CFB system with a twin-riser operated at 4.0 to 10.0 m/s gas velocity and 50 to 550 kg/m2s solids flux. Spent fluid catalytic cracking catalyst particles with 67 μm mean diameter and density of 1500 kg/m3 together with 70% to 80% humid air was used. Solid concentration data were analysed using code prepared using FORTRAN 2008 to get statistical parameters and plot their profiles. Results obtained show that the gas-solid suspension flow in the riser is dominated by low solid concentration in the centre region and high solid concentration in the wall region which forms a core-annulus flow structure. The mean solid concentration in the wall region decreases with riser height from the dense bottom section to less dense in the fully developed flow section at the top of the riser. The gas-solid suspension flow in the centre region is dominated with uniform flow structure while the wall region is dominated with high fluctuations in solid concentration. Further, it was found that the entrance and developing flow sections of the riser exhibit high flow non-uniformities than the fully developed flow section of the riser. The flow non-uniformities in the entrance and developing flow section increase with increase in superficial gas velocity at constant solid flux. The wall region, from the entrance to the top sections of the riser along the axial direction exhibits both dilute and dense suspension flow.展开更多
Super Duplex Stainless Steel has been studied for oil and gas industry applications since the 90 s, but their welding always is a technical issue. Then different methods were developed to meet all requirements present...Super Duplex Stainless Steel has been studied for oil and gas industry applications since the 90 s, but their welding always is a technical issue. Then different methods were developed to meet all requirements presents in ASME standards, where most of are applied for lower production, when compared to other materials such carbon steel. This study accomplished circumferential welding experiments in base material (BM)—UNS S32750 Super Duplex Stainless Steel with a thickness of 3.68 mm. Welding was performed using GMAW (Gas Metal Arc Welding) process with CMT (Cold Metal Transfer) control and the aid of a Motoman robot and a turntable device, which were used to ensure the accurate positioning of the torch and that the welding has been fully implemented in the 1 G position, respectively. This process achieves higher production in relation other welding process usually applied for this material class. The joints which presented adequate dimensional results were, then, subjected to tensile and hardness Vickers tests. To avoid the lack of penetration problem, the welding was performed using the CMT process combined with pulsed arc, thus, resulting in full penetration and improved surface finish. The results have shown that the CMT procedure, combined with pulsed arc, led to an adequate superficial finishing, mechanical properties and corrosion resistance in accomplishment with the requirements presented in applicable standards.展开更多
Fractures are widely distributed in tight reservoirs. Fractures and pore-throats form the flow path of oil/gas/water in reservoirs. How to determine the permeability of fractured porous reservoirs is still difficult. ...Fractures are widely distributed in tight reservoirs. Fractures and pore-throats form the flow path of oil/gas/water in reservoirs. How to determine the permeability of fractured porous reservoirs is still difficult. A group of tight sandstone samples are first used to measure the fractures and analyze the distribution rules between numbers and length, angles. The permeability changing with the fracture’s length and density for different matrixes?is then computed by using pore-fracture network model. At last an empirical formula for predicting the permeability related with the fracture’s length and density is fitted based on the computed data.展开更多
In this paper, the performance of a waste rock transportation process in an open pit mine was assessed by using cycle time data. A computerized truck-excavator dispatch system was used to record the cycle times. The p...In this paper, the performance of a waste rock transportation process in an open pit mine was assessed by using cycle time data. A computerized truck-excavator dispatch system was used to record the cycle times. The process was broken into seven steps (or components of the total cycle), durations of which were recorded for a period of 1 month, leading to N = 60,690 data points or dispatches. The open pit mine studied consisted of 12 waste types loaded by 14 excavators and hauled by 49 trucks (at a trucks-to-excavator ratio of 3.5:1) in 75 changing locations. The string-type data was coded using integers to allow a FORTRAN code to extract process performance parameters using statistical analysis. The study established a wide range of parameters including: the waste material generation rate (about 1.73 million t/month, 81% comprising waste rock), truck fill factor, f, total cycle time (Tct), production capacity, theoretical cycle time, non-productive cycle time Tnp, and cycle time performance ratio (CTPR), denoted as Tpr. The factors affecting the process performance include: truck model, excavator model, location (haul distance and road conditions) and material type. For a fixed material type and tonnage, the PDFs of the cycle time components were logarithmic in nature, capable of differentiating performance variations under different factors. It was concluded that the performance of the waste material transportation system in this mine was determined to be acceptable due to mean value of Tpr = 2.432 being closer to unity. Reduction measures were suggested to minimize the cycle time for the process bottlenecks determined from Pareto analysis (that is, full haul, empty haul and loading processes).展开更多
As an important means of human to change their living environment, building creates important wellbeing for people’s production and life, while as an important means of building construction, civil engineering plays ...As an important means of human to change their living environment, building creates important wellbeing for people’s production and life, while as an important means of building construction, civil engineering plays an absolutely important role in the architectural construction. The fruitful innovation in the construction of civil engineering undoubtedly has a very important meaning and value for the development of civil engineering discipline and for the realization of human wellbeing. This paper makes analysis on several means of technological innovation of civil engineering construction, purposed to promote the practical development of civil engineering through helpful discussion and exploration.展开更多
Groundwater is the most important source of water in the Halabja-Saidsadiq Basin. In this study, to generate a map of groundwater pollution vulnerability of the basin, the standard DRASTIC method has been applied. Due...Groundwater is the most important source of water in the Halabja-Saidsadiq Basin. In this study, to generate a map of groundwater pollution vulnerability of the basin, the standard DRASTIC method has been applied. Due to the close relation between lineament density and groundwater flow and yield, the lineament density map was applied to the standard DRASTIC model in order to ensure accuracy towards the consideration of the effects of potential vulnerability to contamination. A lineament map is extracted from Enhanced Thematic Mapper plus (ETM+) satellite imagery using different techniques in remote sensing and GIS. The lineament density map illustrates that only six classes of lineament density can be identified ranged from (0 - 2.4). The lineament density map was rated and weighted and then converted to lineament index map. This index map is an additional parameter which was added to the standard DRASTIC model so as to map the modi?ed DRASTIC vulnerability in HSB. The standard vulnerability map, classified the basin into four vulnerability index zones: very low (34%), low (13%), moderate (48%) and high (5%). While the modified model classified the area into four categories as well: very low (28.75%), low (14.31%), moderate (46.91%) and high (10.04%). The results demonstrate that there is no significant variation in the rate of vulnerability. Therefore, the nitrate concentration between two different seasons (dry and wet) was analyzed from (30) water wells, considerable variations in nitrate concentration from dry to wet seasons had been noted. Consequently, it confirmed that the HSB are capable to receive the contaminant because of suitability in terms of geological and hydrogeological conditions. Based on this verification, it could be claimed that the effect of lineament density is weak on the vulnerability system in HSB, because of its low density value.展开更多
This work deals with a finite element procedure developed to perform the eigenvalue analysis of damped gyroscopic systems, represented by flexible rotors supported on fluid film journal bearings. The rotor finite elem...This work deals with a finite element procedure developed to perform the eigenvalue analysis of damped gyroscopic systems, represented by flexible rotors supported on fluid film journal bearings. The rotor finite element model is based on the Timoshenko beam theory, accounting for the shaft rotary inertia and gyroscopic moments. The governing equations for the hydrodynamic journal bearing are obtained through the Galerkin weighted residual method applied to the classical Reynolds equation. A perturbation scheme on the fluid film governing equation permits to obtain the zero-th and first order lubrication equations for the bearings, which allow the computation of the dynamic force coefficients associated with the bearing stiffness and damping. The rotor-bearing system equation, which consists of a case of damped gyroscopic equation, is rewritten on state form to compute the complex eigenvalues. The natural frequencies at several operating conditions are obtained and compared to the technical literature data. The influence of the effective damping on the eigenvalue real part sign is analyzed for some examples of rotor-bearing systems, showing how the stability conditions can be predicted by the eigenvalue analysis. The procedure implemented in this work can provide useful guidelines and technical data about the selection of the more appropriate set of bearing parameters for rotating machines operating at stringent conditions.展开更多
Solid waste management is becoming a more serious problem with time especially in developing countries like Iraq. It is not regulated sufficiently in Iraq. At present, there are various techniques used for solid waste...Solid waste management is becoming a more serious problem with time especially in developing countries like Iraq. It is not regulated sufficiently in Iraq. At present, there are various techniques used for solid waste management such as landfill, thermal treatment, biological treatment, recycling etc. The landfill is the most common mode for the disposal of solid waste. There are no regulations for landfill site selection which is quite complex process. In this study, landfill site selection was performed by using Multicriteria Decision Analysis (MCDA) and Geographic Information System (GIS) for the Al-Mseiabqadaa. Even in the case of existing landfills in this qadaa, it’s temporary or non-conforming to the environmental condition. In order to determine landfill site that is good for the inhabitants and the environment several criteria (e.g. as Urban centers, Land use, Airports, Pipes, Power lines, Railways, Roads, Slope, Streams, Surface water, Industrial areas, Oil pipes, Liquid gas pipes, Soil types) were used to select the proper site. The MCDA was used to measure the relative importance weighting for each criterion used. Each map layer was formed with the aid of GIS and final suitability map was created by overlay analyses of each criterion map. According to obtained results, high and low suitable areas were determined in the study area. Field checks were also performed to determine the accuracy and suitability of candidate site.展开更多
The aim of this research was to study and design a solid desiccant dehumidification system suitable for tropical climate to reduce the latent load of air-conditioning system and improve the thermal comfort. Different ...The aim of this research was to study and design a solid desiccant dehumidification system suitable for tropical climate to reduce the latent load of air-conditioning system and improve the thermal comfort. Different dehumidifiers such as desiccant column and desiccant wheel were investigated. The ANSYS and TRASYS software were used to predict the results of dehumidifiers and the desiccant cooling systems, respectively. The desiccant bed contained approximately 15 kg of silica-gel, with 3 mm average diameter. Results indicated that the pressure drop and the adsorption rate of desiccant column are usually higher than those of the desiccant wheel. The feasible and practical adsorption rate of desiccant wheel was 0.102 kgw/h at air flow rate 1.0 kg/min, regenerated air temperature of 55?C and at a wheel speed of 2.5 rpm. The humidity ratio of conditioning space and cooling load of split-type air conditioner was decreased to 0.002 kgw/kgda (14%) and 0.71 kWth (19.26%), respectively. Consequently, the thermal comfort was improved from 0.5 PMV (10.12% PPD) to 0.3 PMV (7.04% PPD).展开更多
Macrophage colony-stimulating factor (CSF-1/M-CSF) is a key factor for the differentiation, growth and survival of monocytes/macrophages and osteoclasts. The functions of M-CSF have been well characterized in mammals....Macrophage colony-stimulating factor (CSF-1/M-CSF) is a key factor for the differentiation, growth and survival of monocytes/macrophages and osteoclasts. The functions of M-CSF have been well characterized in mammals. In this study, we have cloned and sequenced the cDNA of M-CSF2 in grass carp. The grass carp M-CSF2 cDNA was 1487 bp in length, containing an open reading frame of 855 bp that encodes 284 amino acids. The deduced protein of grass carp M-CSF2 possessed same domains similar to its mammalian counterparts. Multiple alignments and phylogenetic tree indicate that the grass carp M-CSF2 exhibits close evolutionary relationship with its counterparts in other teleosts. Lastly, the tissue distribution results also showed that the grass carp M-CSF2 transcript was dominantly expressed in head kidney, kidney and spleen in vivo.展开更多
This paper examines the effect of freezing and thawing on the coarse sand coating chosen to achieve the composition of FRP and concrete in FRP-concrete composite deck. Push-out test specimens with dimensions of 100 &#...This paper examines the effect of freezing and thawing on the coarse sand coating chosen to achieve the composition of FRP and concrete in FRP-concrete composite deck. Push-out test specimens with dimensions of 100 × 100 × 450 mm were subjected to repeated freeze-thaw cycles under wet conditions ranging from -18℃± 2℃ to 4℃ ± 2℃. The failure strength of the interface and the deformation of FRP at failure exhibited by the specimens that experienced 300 freezing-thawing cycles showed a difference of merely 5% compared to those of the specimens that were not subjected to freeze-thaw. This indicates that coarse sand coating is not affected by freezing-thawing cycles and the FRP-concrete composite deck owns sufficient applicability in terms of durability against freezing-thawing.展开更多
Runge-Kutta scheme is one of the versatile numerical tools for the simulation of engineering systems. Despite its wide and acceptable engineering use, there is dearth of relevant literature bordering on visual impress...Runge-Kutta scheme is one of the versatile numerical tools for the simulation of engineering systems. Despite its wide and acceptable engineering use, there is dearth of relevant literature bordering on visual impression possibility among different schemes coefficients which is the strong motivation for the present investigation of the third and fourth order schemes. The present study capitalise on results of tedious computation involving Taylor series expansion equivalent supplemented with Butcher assumptions and constraint equations of well-known works which captures the essential relationship between the coefficients. The simulation proceeds from random but valid specification of two out of the total coefficients possible per scheme. However the remaining coefficients are evaluated with application of appropriate function relationship. Eight and thirteen unknown coefficients were simulated respectively for third and fourth schemes over a total of five thousand cases each for relevant distribution statistics and scatter plots analysis for the purpose of scheme comparison and visual import. The respective three and four coefficients of the slope estimate for the third and fourth schemes have mix sign for large number of simulated cases. However, none of the two schemes have above three of these coefficients lesser than zero. The percentages of simulation results with two coefficients lesser than zero dominate and are respectively 56.88 and 77.10 for third and fourth schemes. It was observed that both popular third and fourth schemes belong to none of the coefficients being zero classification with respective percentage of 0.72 and 3.28 intotal simulated cases. The comparisons of corresponding scatter plots are visually exciting. The overall difference between corresponding scatter plots and distribution results can be used to justify the accuracy of fourth scheme over its counterpart third scheme.展开更多
Since the introduction of Ant Colony Optimization (ACO) technique in 1992, the algorithm starts to gain popularity due to its attractive features. However, several shortcomings such as slow convergence and stagnation ...Since the introduction of Ant Colony Optimization (ACO) technique in 1992, the algorithm starts to gain popularity due to its attractive features. However, several shortcomings such as slow convergence and stagnation motivate many researchers to stop further implementation of ACO. Therefore, in order to overcome these drawbacks, ACO is proposed to be combined with Differential Evolution (DE) and cloning process. This paper presents Differential Evolution Immunized Ant Colony Optimization (DEIANT) technique in solving economic load dispatch problem. The combination creates a new algorithm that will be termed as Differential Evolution Immunized Ant Colony Optimization (DEIANT). DEIANT was utilized to optimize economic load dispatch problem. A comparison was made between DEIANT and classical ACO to evaluate the performance of the new algorithm. In realizing the effectiveness of the proposed technique, IEEE 57-Bus Reliable Test System (RTS) has been used as the test specimen. Results obtained from the study revealed that the proposed DEIANT has superior computation time.展开更多
In this paper, the model of chiller power consumption is built by using the regression analysis. While taking the parameters from the operation data of chiller into consideration simultaneously, i.e. Partial Load Rati...In this paper, the model of chiller power consumption is built by using the regression analysis. While taking the parameters from the operation data of chiller into consideration simultaneously, i.e. Partial Load Ratio (PLR), chilled water supply temperature and cooling water return temperature, the prediction results are quite accurate, and its accuracy reaches over 99% in short-term prediction when compared with the actual power consumption. This method can be used to validate the benefits of the chiller’s energy saving method. The validation items include: the effect of water flow change on chiller’s performance while multiple chillers operate in parallel;the power consumption analysis of centrifugal chiller operating with or without frequency conversion;as well as the discussion on whether the cleaning of condenser coil can improve the Coefficient of Performance (COP) of chiller or not. The case study results show that, while multiple chillers operate in parallel, the water flow change has limited effect on the performance of chiller. However, about 36% electricity can be saved averagely when the chiller controls the frequency of electric power source at partial load, and the cleaning of condenser coil can increase the COP by 3.08%.展开更多
Romashkino oil field has large oilfield area, small formation dip, many reservoir layers, wide oil-water transition zone and complicated sedimentary environment. Since development, 3 overall development plannings and ...Romashkino oil field has large oilfield area, small formation dip, many reservoir layers, wide oil-water transition zone and complicated sedimentary environment. Since development, 3 overall development plannings and adjustments of individual block have been established. This achieves a high oil production. However, the recoverable reserves of major oil layer with high production become smaller and smaller and the water cut increases over time, the production ability of oil layer decreases. The development status of oil layer of mining siltstone, oil-water transition zone and oil layer with upswept injected water cannot be changed under present dilute well network condition, because there is no reinforced measurement to water well. This results the low oil production of Romashkino oil field. In order to improve oil production rate and reach the designed oil recovery, Romashkino oil field has been implemented many added cuttings since development. Resent researches about Romashkino oil field show: in later oilfield development stage, sidetrack and lateral drilling horizontal wells technology is very reasonable;formation hydraulic fracturing technology has been widely used in recent years;in tertiary oil recovery, sweep efficiency and flooding efficiency related technologies have been taken. This offers reference and guidance for the effective and reasonable oil field development in later period.展开更多
The aim of this work was to develop an in vitro model to study mechanical compression effects on cartilage. A pressure-controlled compression device was used in this study. Cartilage explants obtained from human knee ...The aim of this work was to develop an in vitro model to study mechanical compression effects on cartilage. A pressure-controlled compression device was used in this study. Cartilage explants obtained from human knee were compressed at 1MPa/1Hz for 7 hours (30 min ON, 30 min OFF) under normoxia (5% CO2, 21% O2) or hypoxia (5% CO2, 5% O2). Cell viability was analyzed while nitric oxide (NO) and glycosaminoglycans (GAG) release was assayed in culture media. Mechanical stimulation increased NO production and GAG release by human cartilage explants under normoxia and hypoxia culture. In normoxia and hypoxia conditions, mechanical stimulation alters human OA cartilage metabolism. There is also, an increase in matrix degradation after compression, as shown by levels of GAG found in culture media. This study put in evidence the importance of mechanical compression in the progression of the osteoarthritis and present and in vitro model for mechanobiological and pharmacological studies.展开更多
Designing of a multi-purpose plant as one of the well-known manufacturing systems is more challenging than other manufacturing systems. This paper applies a stochastic colored Petri net (CPN) to design and analyze mul...Designing of a multi-purpose plant as one of the well-known manufacturing systems is more challenging than other manufacturing systems. This paper applies a stochastic colored Petri net (CPN) to design and analyze multi-purpose plants. A simple approach is proposed to determine the utilization of shared resources and to reduce the equipment’s idle times. Three scenarios are presented to describe the proposed model. Generally, according to desire of a decision maker, different scenarios can be considered in the model to achieve to the expected design or plant configuration. The main characteristics of the proposed model are flexibility, the easiness of practical application and the simulation of the model in an easy way.展开更多
This paper utilizes numerical analysis method to determine the influence of non-condensation gas on the thermal performance of a heat pipe. The temperature difference between the evaporation and condensation sections ...This paper utilizes numerical analysis method to determine the influence of non-condensation gas on the thermal performance of a heat pipe. The temperature difference between the evaporation and condensation sections of a single heat pipe and maximum heat capacity are the index of the thermal performance of a heat pipe for a thermal module manufacturer. The thermal performance of a heat pipe with lower temperature difference between the evaporation and condensation sections is better than that of higher temperature dif- ference at the same input power. The results show that the maximum heat capacity reaches the highest point, as the amount of the non-condensation gas of a heat pipe is the lowest value and the temperature difference between evaporation and condensation sections is the smallest one. The temperature difference is under 1?C while the percentage of the non-condensation gas is under 8 × 10?5%, and the heat pipe has the maximum heat capacity.展开更多
文摘The use of three-dimensional maps is more effective than two-dimensional maps in representing the Earth’s surface. However, the traditional methods used to create digital surface models are not efficient for capturing the details of Earth’s features. This is because they represent only three-dimensional objects in a single texture and do not provide a realistic representation of the real world. Additionally, there is a growing demand for up-to-date and accurate geo-information, particularly in urban areas. To address this challenge, a new technique is proposed in this study that involves integrating remote sensing, Geographic Information System, and Architecture Environment software to generate a highly-detailed three-dimensional model. The method described in this study includes several steps such as acquiring high-resolution satellite imagery, gathering ground truth data, performing radiometric and geometric corrections during image preprocessing, producing a 2D map of the region of interest, constructing a digital surface model by extending the building outlines, and transforming the model into multi-patch layers to create a 3D model for each object individually. The research findings indicate that the digital surface model obtained with comprehensive information is suitable for different purposes, such as environmental research, urban development and expansion planning, and shape recognition tasks.
文摘In the framework of this research, the principle focus is to analyze the effects of fluid Prandtl number (Pr) on natural convection heat transfer in a volumetrically heated molten pool. As a part of the work, numerical analysis is performed for hemispherical 3-D vessel slice to investigate the physics of the effect of Pr number on convective heat transfer characteristics in the melt pool. The investigation is based on ANSYS FLUET, where natural convection heat transfer effect is taken into consideration by Phase-change Effective Convectivity Model (PECM), which is implemented with FLUENT CFD as User Defined Function (UDF), programed by the user. The PECM is tested first by a benchmark test against CFD to gain confidence in its applicability as an analysis tool. Different simulant materials are used with their thermo-physical properties representing different Pr number as input for modelling for both single and double layer melt pool configuration. The selected modelling approach is validated against RASPLAV experimental result with respect to the inner temperature distribution that qualifies our model to run in the proceeding calculation. It is ensured that an isothermal boundary condition (343 K) is applied along vessel outer wall throughout the series of simulation cases. The corresponding Rayleigh number (Ra) ranges from 1014 - 1015 and Prandtl number (Pr) 3 - 5. It is found that the fluid Pr number has small effects on the averaged Nu numbers in the convection-dominated regions. The decrease in the Pr number may cause a decrease in the Nu numbers on the top and sidewalls of cavities. In the conduction dominated regions (stably stratified bottom parts of enclosure), the effect of fluid Pr number on heat transfer is more significant and it grows with increasing Ra number.
文摘Statistical analysis of the entrance and wall dynamics of a high-flux gas-solid riser was done using solid concentration time series data collected from a 76 mm internal diameter and 10 m high riser of a CFB system with a twin-riser operated at 4.0 to 10.0 m/s gas velocity and 50 to 550 kg/m2s solids flux. Spent fluid catalytic cracking catalyst particles with 67 μm mean diameter and density of 1500 kg/m3 together with 70% to 80% humid air was used. Solid concentration data were analysed using code prepared using FORTRAN 2008 to get statistical parameters and plot their profiles. Results obtained show that the gas-solid suspension flow in the riser is dominated by low solid concentration in the centre region and high solid concentration in the wall region which forms a core-annulus flow structure. The mean solid concentration in the wall region decreases with riser height from the dense bottom section to less dense in the fully developed flow section at the top of the riser. The gas-solid suspension flow in the centre region is dominated with uniform flow structure while the wall region is dominated with high fluctuations in solid concentration. Further, it was found that the entrance and developing flow sections of the riser exhibit high flow non-uniformities than the fully developed flow section of the riser. The flow non-uniformities in the entrance and developing flow section increase with increase in superficial gas velocity at constant solid flux. The wall region, from the entrance to the top sections of the riser along the axial direction exhibits both dilute and dense suspension flow.
文摘Super Duplex Stainless Steel has been studied for oil and gas industry applications since the 90 s, but their welding always is a technical issue. Then different methods were developed to meet all requirements presents in ASME standards, where most of are applied for lower production, when compared to other materials such carbon steel. This study accomplished circumferential welding experiments in base material (BM)—UNS S32750 Super Duplex Stainless Steel with a thickness of 3.68 mm. Welding was performed using GMAW (Gas Metal Arc Welding) process with CMT (Cold Metal Transfer) control and the aid of a Motoman robot and a turntable device, which were used to ensure the accurate positioning of the torch and that the welding has been fully implemented in the 1 G position, respectively. This process achieves higher production in relation other welding process usually applied for this material class. The joints which presented adequate dimensional results were, then, subjected to tensile and hardness Vickers tests. To avoid the lack of penetration problem, the welding was performed using the CMT process combined with pulsed arc, thus, resulting in full penetration and improved surface finish. The results have shown that the CMT procedure, combined with pulsed arc, led to an adequate superficial finishing, mechanical properties and corrosion resistance in accomplishment with the requirements presented in applicable standards.
文摘Fractures are widely distributed in tight reservoirs. Fractures and pore-throats form the flow path of oil/gas/water in reservoirs. How to determine the permeability of fractured porous reservoirs is still difficult. A group of tight sandstone samples are first used to measure the fractures and analyze the distribution rules between numbers and length, angles. The permeability changing with the fracture’s length and density for different matrixes?is then computed by using pore-fracture network model. At last an empirical formula for predicting the permeability related with the fracture’s length and density is fitted based on the computed data.
文摘In this paper, the performance of a waste rock transportation process in an open pit mine was assessed by using cycle time data. A computerized truck-excavator dispatch system was used to record the cycle times. The process was broken into seven steps (or components of the total cycle), durations of which were recorded for a period of 1 month, leading to N = 60,690 data points or dispatches. The open pit mine studied consisted of 12 waste types loaded by 14 excavators and hauled by 49 trucks (at a trucks-to-excavator ratio of 3.5:1) in 75 changing locations. The string-type data was coded using integers to allow a FORTRAN code to extract process performance parameters using statistical analysis. The study established a wide range of parameters including: the waste material generation rate (about 1.73 million t/month, 81% comprising waste rock), truck fill factor, f, total cycle time (Tct), production capacity, theoretical cycle time, non-productive cycle time Tnp, and cycle time performance ratio (CTPR), denoted as Tpr. The factors affecting the process performance include: truck model, excavator model, location (haul distance and road conditions) and material type. For a fixed material type and tonnage, the PDFs of the cycle time components were logarithmic in nature, capable of differentiating performance variations under different factors. It was concluded that the performance of the waste material transportation system in this mine was determined to be acceptable due to mean value of Tpr = 2.432 being closer to unity. Reduction measures were suggested to minimize the cycle time for the process bottlenecks determined from Pareto analysis (that is, full haul, empty haul and loading processes).
文摘As an important means of human to change their living environment, building creates important wellbeing for people’s production and life, while as an important means of building construction, civil engineering plays an absolutely important role in the architectural construction. The fruitful innovation in the construction of civil engineering undoubtedly has a very important meaning and value for the development of civil engineering discipline and for the realization of human wellbeing. This paper makes analysis on several means of technological innovation of civil engineering construction, purposed to promote the practical development of civil engineering through helpful discussion and exploration.
文摘Groundwater is the most important source of water in the Halabja-Saidsadiq Basin. In this study, to generate a map of groundwater pollution vulnerability of the basin, the standard DRASTIC method has been applied. Due to the close relation between lineament density and groundwater flow and yield, the lineament density map was applied to the standard DRASTIC model in order to ensure accuracy towards the consideration of the effects of potential vulnerability to contamination. A lineament map is extracted from Enhanced Thematic Mapper plus (ETM+) satellite imagery using different techniques in remote sensing and GIS. The lineament density map illustrates that only six classes of lineament density can be identified ranged from (0 - 2.4). The lineament density map was rated and weighted and then converted to lineament index map. This index map is an additional parameter which was added to the standard DRASTIC model so as to map the modi?ed DRASTIC vulnerability in HSB. The standard vulnerability map, classified the basin into four vulnerability index zones: very low (34%), low (13%), moderate (48%) and high (5%). While the modified model classified the area into four categories as well: very low (28.75%), low (14.31%), moderate (46.91%) and high (10.04%). The results demonstrate that there is no significant variation in the rate of vulnerability. Therefore, the nitrate concentration between two different seasons (dry and wet) was analyzed from (30) water wells, considerable variations in nitrate concentration from dry to wet seasons had been noted. Consequently, it confirmed that the HSB are capable to receive the contaminant because of suitability in terms of geological and hydrogeological conditions. Based on this verification, it could be claimed that the effect of lineament density is weak on the vulnerability system in HSB, because of its low density value.
文摘This work deals with a finite element procedure developed to perform the eigenvalue analysis of damped gyroscopic systems, represented by flexible rotors supported on fluid film journal bearings. The rotor finite element model is based on the Timoshenko beam theory, accounting for the shaft rotary inertia and gyroscopic moments. The governing equations for the hydrodynamic journal bearing are obtained through the Galerkin weighted residual method applied to the classical Reynolds equation. A perturbation scheme on the fluid film governing equation permits to obtain the zero-th and first order lubrication equations for the bearings, which allow the computation of the dynamic force coefficients associated with the bearing stiffness and damping. The rotor-bearing system equation, which consists of a case of damped gyroscopic equation, is rewritten on state form to compute the complex eigenvalues. The natural frequencies at several operating conditions are obtained and compared to the technical literature data. The influence of the effective damping on the eigenvalue real part sign is analyzed for some examples of rotor-bearing systems, showing how the stability conditions can be predicted by the eigenvalue analysis. The procedure implemented in this work can provide useful guidelines and technical data about the selection of the more appropriate set of bearing parameters for rotating machines operating at stringent conditions.
文摘Solid waste management is becoming a more serious problem with time especially in developing countries like Iraq. It is not regulated sufficiently in Iraq. At present, there are various techniques used for solid waste management such as landfill, thermal treatment, biological treatment, recycling etc. The landfill is the most common mode for the disposal of solid waste. There are no regulations for landfill site selection which is quite complex process. In this study, landfill site selection was performed by using Multicriteria Decision Analysis (MCDA) and Geographic Information System (GIS) for the Al-Mseiabqadaa. Even in the case of existing landfills in this qadaa, it’s temporary or non-conforming to the environmental condition. In order to determine landfill site that is good for the inhabitants and the environment several criteria (e.g. as Urban centers, Land use, Airports, Pipes, Power lines, Railways, Roads, Slope, Streams, Surface water, Industrial areas, Oil pipes, Liquid gas pipes, Soil types) were used to select the proper site. The MCDA was used to measure the relative importance weighting for each criterion used. Each map layer was formed with the aid of GIS and final suitability map was created by overlay analyses of each criterion map. According to obtained results, high and low suitable areas were determined in the study area. Field checks were also performed to determine the accuracy and suitability of candidate site.
文摘The aim of this research was to study and design a solid desiccant dehumidification system suitable for tropical climate to reduce the latent load of air-conditioning system and improve the thermal comfort. Different dehumidifiers such as desiccant column and desiccant wheel were investigated. The ANSYS and TRASYS software were used to predict the results of dehumidifiers and the desiccant cooling systems, respectively. The desiccant bed contained approximately 15 kg of silica-gel, with 3 mm average diameter. Results indicated that the pressure drop and the adsorption rate of desiccant column are usually higher than those of the desiccant wheel. The feasible and practical adsorption rate of desiccant wheel was 0.102 kgw/h at air flow rate 1.0 kg/min, regenerated air temperature of 55?C and at a wheel speed of 2.5 rpm. The humidity ratio of conditioning space and cooling load of split-type air conditioner was decreased to 0.002 kgw/kgda (14%) and 0.71 kWth (19.26%), respectively. Consequently, the thermal comfort was improved from 0.5 PMV (10.12% PPD) to 0.3 PMV (7.04% PPD).
文摘Macrophage colony-stimulating factor (CSF-1/M-CSF) is a key factor for the differentiation, growth and survival of monocytes/macrophages and osteoclasts. The functions of M-CSF have been well characterized in mammals. In this study, we have cloned and sequenced the cDNA of M-CSF2 in grass carp. The grass carp M-CSF2 cDNA was 1487 bp in length, containing an open reading frame of 855 bp that encodes 284 amino acids. The deduced protein of grass carp M-CSF2 possessed same domains similar to its mammalian counterparts. Multiple alignments and phylogenetic tree indicate that the grass carp M-CSF2 exhibits close evolutionary relationship with its counterparts in other teleosts. Lastly, the tissue distribution results also showed that the grass carp M-CSF2 transcript was dominantly expressed in head kidney, kidney and spleen in vivo.
文摘This paper examines the effect of freezing and thawing on the coarse sand coating chosen to achieve the composition of FRP and concrete in FRP-concrete composite deck. Push-out test specimens with dimensions of 100 × 100 × 450 mm were subjected to repeated freeze-thaw cycles under wet conditions ranging from -18℃± 2℃ to 4℃ ± 2℃. The failure strength of the interface and the deformation of FRP at failure exhibited by the specimens that experienced 300 freezing-thawing cycles showed a difference of merely 5% compared to those of the specimens that were not subjected to freeze-thaw. This indicates that coarse sand coating is not affected by freezing-thawing cycles and the FRP-concrete composite deck owns sufficient applicability in terms of durability against freezing-thawing.
文摘Runge-Kutta scheme is one of the versatile numerical tools for the simulation of engineering systems. Despite its wide and acceptable engineering use, there is dearth of relevant literature bordering on visual impression possibility among different schemes coefficients which is the strong motivation for the present investigation of the third and fourth order schemes. The present study capitalise on results of tedious computation involving Taylor series expansion equivalent supplemented with Butcher assumptions and constraint equations of well-known works which captures the essential relationship between the coefficients. The simulation proceeds from random but valid specification of two out of the total coefficients possible per scheme. However the remaining coefficients are evaluated with application of appropriate function relationship. Eight and thirteen unknown coefficients were simulated respectively for third and fourth schemes over a total of five thousand cases each for relevant distribution statistics and scatter plots analysis for the purpose of scheme comparison and visual import. The respective three and four coefficients of the slope estimate for the third and fourth schemes have mix sign for large number of simulated cases. However, none of the two schemes have above three of these coefficients lesser than zero. The percentages of simulation results with two coefficients lesser than zero dominate and are respectively 56.88 and 77.10 for third and fourth schemes. It was observed that both popular third and fourth schemes belong to none of the coefficients being zero classification with respective percentage of 0.72 and 3.28 intotal simulated cases. The comparisons of corresponding scatter plots are visually exciting. The overall difference between corresponding scatter plots and distribution results can be used to justify the accuracy of fourth scheme over its counterpart third scheme.
文摘Since the introduction of Ant Colony Optimization (ACO) technique in 1992, the algorithm starts to gain popularity due to its attractive features. However, several shortcomings such as slow convergence and stagnation motivate many researchers to stop further implementation of ACO. Therefore, in order to overcome these drawbacks, ACO is proposed to be combined with Differential Evolution (DE) and cloning process. This paper presents Differential Evolution Immunized Ant Colony Optimization (DEIANT) technique in solving economic load dispatch problem. The combination creates a new algorithm that will be termed as Differential Evolution Immunized Ant Colony Optimization (DEIANT). DEIANT was utilized to optimize economic load dispatch problem. A comparison was made between DEIANT and classical ACO to evaluate the performance of the new algorithm. In realizing the effectiveness of the proposed technique, IEEE 57-Bus Reliable Test System (RTS) has been used as the test specimen. Results obtained from the study revealed that the proposed DEIANT has superior computation time.
文摘In this paper, the model of chiller power consumption is built by using the regression analysis. While taking the parameters from the operation data of chiller into consideration simultaneously, i.e. Partial Load Ratio (PLR), chilled water supply temperature and cooling water return temperature, the prediction results are quite accurate, and its accuracy reaches over 99% in short-term prediction when compared with the actual power consumption. This method can be used to validate the benefits of the chiller’s energy saving method. The validation items include: the effect of water flow change on chiller’s performance while multiple chillers operate in parallel;the power consumption analysis of centrifugal chiller operating with or without frequency conversion;as well as the discussion on whether the cleaning of condenser coil can improve the Coefficient of Performance (COP) of chiller or not. The case study results show that, while multiple chillers operate in parallel, the water flow change has limited effect on the performance of chiller. However, about 36% electricity can be saved averagely when the chiller controls the frequency of electric power source at partial load, and the cleaning of condenser coil can increase the COP by 3.08%.
文摘Romashkino oil field has large oilfield area, small formation dip, many reservoir layers, wide oil-water transition zone and complicated sedimentary environment. Since development, 3 overall development plannings and adjustments of individual block have been established. This achieves a high oil production. However, the recoverable reserves of major oil layer with high production become smaller and smaller and the water cut increases over time, the production ability of oil layer decreases. The development status of oil layer of mining siltstone, oil-water transition zone and oil layer with upswept injected water cannot be changed under present dilute well network condition, because there is no reinforced measurement to water well. This results the low oil production of Romashkino oil field. In order to improve oil production rate and reach the designed oil recovery, Romashkino oil field has been implemented many added cuttings since development. Resent researches about Romashkino oil field show: in later oilfield development stage, sidetrack and lateral drilling horizontal wells technology is very reasonable;formation hydraulic fracturing technology has been widely used in recent years;in tertiary oil recovery, sweep efficiency and flooding efficiency related technologies have been taken. This offers reference and guidance for the effective and reasonable oil field development in later period.
文摘The aim of this work was to develop an in vitro model to study mechanical compression effects on cartilage. A pressure-controlled compression device was used in this study. Cartilage explants obtained from human knee were compressed at 1MPa/1Hz for 7 hours (30 min ON, 30 min OFF) under normoxia (5% CO2, 21% O2) or hypoxia (5% CO2, 5% O2). Cell viability was analyzed while nitric oxide (NO) and glycosaminoglycans (GAG) release was assayed in culture media. Mechanical stimulation increased NO production and GAG release by human cartilage explants under normoxia and hypoxia culture. In normoxia and hypoxia conditions, mechanical stimulation alters human OA cartilage metabolism. There is also, an increase in matrix degradation after compression, as shown by levels of GAG found in culture media. This study put in evidence the importance of mechanical compression in the progression of the osteoarthritis and present and in vitro model for mechanobiological and pharmacological studies.
文摘Designing of a multi-purpose plant as one of the well-known manufacturing systems is more challenging than other manufacturing systems. This paper applies a stochastic colored Petri net (CPN) to design and analyze multi-purpose plants. A simple approach is proposed to determine the utilization of shared resources and to reduce the equipment’s idle times. Three scenarios are presented to describe the proposed model. Generally, according to desire of a decision maker, different scenarios can be considered in the model to achieve to the expected design or plant configuration. The main characteristics of the proposed model are flexibility, the easiness of practical application and the simulation of the model in an easy way.
文摘This paper utilizes numerical analysis method to determine the influence of non-condensation gas on the thermal performance of a heat pipe. The temperature difference between the evaporation and condensation sections of a single heat pipe and maximum heat capacity are the index of the thermal performance of a heat pipe for a thermal module manufacturer. The thermal performance of a heat pipe with lower temperature difference between the evaporation and condensation sections is better than that of higher temperature dif- ference at the same input power. The results show that the maximum heat capacity reaches the highest point, as the amount of the non-condensation gas of a heat pipe is the lowest value and the temperature difference between evaporation and condensation sections is the smallest one. The temperature difference is under 1?C while the percentage of the non-condensation gas is under 8 × 10?5%, and the heat pipe has the maximum heat capacity.
