The present paper discusses the modeling of tool geometry effects on the friction stir aluminum welds using response surface methodology. The friction stir welding tools were designed with different shoulder and tool ...The present paper discusses the modeling of tool geometry effects on the friction stir aluminum welds using response surface methodology. The friction stir welding tools were designed with different shoulder and tool probe geometries based on a design matrix. The matrix for the tool designing was made for three types of tools, based on three types of probes, with three levels each for defining the shoulder surface type and probe profile geometries. Then, the effects of tool shoulder and probe geometries on friction stirred aluminum welds were experimentally investigated with respect to weld strength, weld cross section area, grain size of weld and grain size of thermo-mechanically affected zone. These effects were modeled using multiple and response surface regression analysis. The response surface regression modeling were found to be appropriate for defining the friction stir weldment characteristics.展开更多
In marine application,marine grade steel is generally used for haul and superstructures.However,aluminum has also become a good choice due to its lightweight qualities,while rusting of aluminum is minimal compared to ...In marine application,marine grade steel is generally used for haul and superstructures.However,aluminum has also become a good choice due to its lightweight qualities,while rusting of aluminum is minimal compared to steel.In this paper a study on friction stir welding of aluminum alloys was presented.The present investigation deals with the effects of different friction stir welding tool geometries on mechanical strength and the microstructure properties of aluminum alloy welds.Three distinct tool geometries with different types of shoulder and tool probe profiles were used in the investigation according to the design matrix.The effects of each tool shoulder and probe geometry on the weld was evaluated.It was also observed that the friction stir weld tool geometry has a significant effect on the weldment reinforcement,microhardness,and weld strength.展开更多
A comprehensive landslide inventory and susceptibility maps are prerequisite for developing and implementing landslide mitigation strategies. Landslide susceptibility maps for the landslides prone regions in northern ...A comprehensive landslide inventory and susceptibility maps are prerequisite for developing and implementing landslide mitigation strategies. Landslide susceptibility maps for the landslides prone regions in northern Pakistan are rarely available. The Hunza-Nagar valley in northern Pakistan is known for its frequent and devastating landslides. In this paper, we have developed a landslide inventory map for Hunza-Nagar valley by using the visual interpretation of the SPOT-5 satellite imagery and mapped a total of 172 landslides. The landslide inventory was subsequently divided into modelling and validation data sets. For the development of landslide susceptibility map seven discrete landslide causative factors were correlated with the landslide inventory map using weight of evidence and frequency ratio statistical models. Four different models of conditional independence were used for the selection of landslide causative factors. The produced landslides susceptibility maps were validated by the success rate and area under curves criteria. The prediction power of the models was also validated with the prediction rate curve. The validation results shows that the success rate curves of the weight of evidence and the frequency models are 82% and 79%, respectively. The prediction accuracy results obtained from this study are 84% for weight of evidence model and 80% for the frequency ratio model. Finally, the landslide susceptibility index maps were classified into five different varying susceptibility zones. The validation and prediction result indicates that the weight of evidence and frequency ratio model are reliable to produce an accurate landslide susceptibility map, which may be helpful for landslides management strategies.展开更多
Monitoring of industrial plant performance and detection on flaws is important to the successful operation on industrial production units. Malfunctioning equipment can greatly impact plant performance by reducing the ...Monitoring of industrial plant performance and detection on flaws is important to the successful operation on industrial production units. Malfunctioning equipment can greatly impact plant performance by reducing the efficiency and increasing the production cost. Phenomenological equations cannot properly describe industrial processes. Thus, it is necessary to develop new equations for model industrial operations. The purpose of this study is to develop an empirical model for industrial demethanizer tower which is malfunctioning due to an error in the design in one of its plates. A nonlinear statistical model was designed to predict the pressure variation in the column, and consequently, the flooding conditions. This model was validated using industrial data to predict the maximum loads in the column.展开更多
In past terrorist attacks, vehicle borne improvised explosive devices (VBIED) have been the primary manner of attacking buildings and infrastructures. Preventing unauthorized vehicles from approaching a protected area...In past terrorist attacks, vehicle borne improvised explosive devices (VBIED) have been the primary manner of attacking buildings and infrastructures. Preventing unauthorized vehicles from approaching a protected area with anti-ram systems would maintain an established standoff distance against moving and stationary vehicles and consequently reduce blast and debris threats. This strategy has been considered the first line of defence against terrorists. Several types of anti-ram devices have been developed in accordance with U. S. Department of State K-rating criteria, for example, wedge barriers, rising beams, sliding/swing gates, and drop arms. However, these devices typically need a deep foundation for installation and can't be implemented into many locations where a depth of excavation is limited in order to protect utility lines of buildings and infrastructures. This paper presents a recent development of a series of shallow footing anti-ram bollard systems (SFABS) that can satisfy K-12 rating with only five-inch thick footing. A high-fidelity physics based finite element technique with a vehicle crash model is used for predicting anti-ram capacity and determining design parameters of the SFABS. Full-scale vehicle crash tests of the developed SFABS systems have been carried out to validate the design and analysis.展开更多
The goal of this article is dual: first, introducing a new model of accident named STAMP (systems-theoretic accident modeling and processes); then applying the model to an innovative process for the treatment of co...The goal of this article is dual: first, introducing a new model of accident named STAMP (systems-theoretic accident modeling and processes); then applying the model to an innovative process for the treatment of contaminated substances and the re-use of treated substances. This article is a demonstration for a need of a new tool to take into account hazards and safety within socio-technical systems.展开更多
The machining accuracy of workpiece is influenced by its orientation deviation, which is caused by the fixture-workpiece error. Based on the spatial coordinate theory, the orientation deviation of workpiece is measure...The machining accuracy of workpiece is influenced by its orientation deviation, which is caused by the fixture-workpiece error. Based on the spatial coordinate theory, the orientation deviation of workpiece is measured by using an on-machine verification system, which can take into account the errors resulting from fixture manufacturing, installation and adjustment, location and clamping of workpiece. According to the least square method, the model of orientation deviation is built to determine the relationship between the theoretical and actual coordinate systems. The influence of orientation deviation on machining accuracy is quantified, and it is shown that the orientation deviation only affects the dimensional precision and position precision, rather than shape precision. In the experiment, the compensation processing of realtime errors was conducted, and the perpendicularity and inclination errors of the tetragonal part were reduced by 38.46% and 47.06%, respectively.展开更多
In this paper, the authors present the development of a data modelling tool that visualizes the transformation process of an "Entity-Relationship" Diagram (ERD) into a relational database schema. The authors' foc...In this paper, the authors present the development of a data modelling tool that visualizes the transformation process of an "Entity-Relationship" Diagram (ERD) into a relational database schema. The authors' focus is the design of a tool for educational purposes and its implementation on e-learning database course. The tool presents two stages of database design. The first stage is to draw ERD graphically and validate it. The drawing is done by a learner. Then at second stage, the system enables automatically transformation of ERD to relational database schema by using common rules. Thus, the learner could understand more easily how to apply the theoretical material. A detailed description of system functionalities and algorithm for the conversion are proposed. Finally, a user interface and usage aspects are exposed.展开更多
A novel three-phase active power filter (APF) circuit with photovoltaic (PV) system to improve the quality of service and to reduce the capacity of energy storage capacitor is presented. The energy balance concept...A novel three-phase active power filter (APF) circuit with photovoltaic (PV) system to improve the quality of service and to reduce the capacity of energy storage capacitor is presented. The energy balance concept and sampling technique were used to simplify the calculation algorithm for the required utility source current and to control the voltage of the energy storage capacitor. The feasibility was verified by using the Pspice simulations and experiments. When the APF mode was used during non-operational period, not only the utilization rate, power factor and power quality could be improved, but also the capacity of energy storage capacitor could sparing. As the results, the advantages of the APF circuit are simplicity of control circuits, low cost, and good transient response.展开更多
With the development and decreasing cost of sequencing techniques, it is possible for scientists to conduct deeper research in phylogenomics. During the procedure of phylogenomic analysis, the mostimportant and vitale...With the development and decreasing cost of sequencing techniques, it is possible for scientists to conduct deeper research in phylogenomics. During the procedure of phylogenomic analysis, the mostimportant and vitalest step is orthology prediction, for that the prerequisite to phylogenetic reconstruction is that the genes being compared are orthologous. Here we briefly review the related concept of orthology anddifferent methods for orthology prediction. We also provide recommendations to give some advice for better selection of orthology prediction methods.展开更多
Gear skiving is a promising gear cutting technology that can achieve a multiple faster internal gear cutting process than that of gear shaping. However,the kinematic system complicates skiving process,resulting in sev...Gear skiving is a promising gear cutting technology that can achieve a multiple faster internal gear cutting process than that of gear shaping. However,the kinematic system complicates skiving process,resulting in severe crater wear due to the intense variation of local cutting features. In particular,the negative rake angle near the cut-out is recognized as influential factor affecting the cutter wear progress,which needs the sophisticated simulation approach to elucidate the underlying cutting mechanism. In this research,the influence of the rake angle,e.g. top and side nominal rake angles of the cutter,is studied to further understand its role in the gear skiving process,for seeking the possibility of skiving process improvement by calculating the effective rake angle. As a result,the top and side rake angles of the cutter can both increase the effective rake angle when compared with the case of the none-rake angle,leading to an enhanced skiving process. This work provides fundamental knowledge of the rake angle for the gear skiving research,contributing to the optimization on the cutter parameters by considering the effective rake angle.展开更多
Providing a decent housing is a major challenge for governments and development authorities in Jordan and Arab countries. Nevertheless, the growing number of population falling under poverty put more demand on low cos...Providing a decent housing is a major challenge for governments and development authorities in Jordan and Arab countries. Nevertheless, the growing number of population falling under poverty put more demand on low cost housing options. The goal of the research was to find ways of rationalizing the cost and determine the appropriate standards and models that achieve an acceptable equation between cost and performance, and that during design and construction phases. The study follows the method of investigation and analysis to get factors that reduce the cost of the house construction for poor families by means of the concept of standardization in traditional (popular) buildings system. The research confirms that the traditional system has many advantages that could strengthen towards development a low-cost building system by applying the principles of standardization through architectural, structural and electro-mechanical considerations of design. Research recommends taking on studies for low cost building system through comprehensive analytical study of local building experiences.展开更多
End windings of generators are excited to vibrations due to electromagnetic forces which can cause severe damage and noise. To avoid this, it is important to predict the natural frequencies and modes of the end windin...End windings of generators are excited to vibrations due to electromagnetic forces which can cause severe damage and noise. To avoid this, it is important to predict the natural frequencies and modes of the end windings with finite elements. Due to the complex structure and unknown boundary conditions, the conventionally calculation of stator end windings has been very difficult and time consuming up to now. This paper describes the development of a full parameterized modeling tool, which allows a quick calculation of natural frequencies during the design phase of the generator. To keep the computing time low, it is important to find a way to get exact calculation results without detailed modeling of all pans. Additionally, special attention was paid to the active part, which has been replaced by spring-damper elements, and the determination of their stiffness via experimental modal analysis combined with finite element calculations.展开更多
In this paper, a numerical modeling tool is described which can be used to explore various aspects of four dimensional variational data assimilation and parameter estimation arising in geophysical, environmental, biol...In this paper, a numerical modeling tool is described which can be used to explore various aspects of four dimensional variational data assimilation and parameter estimation arising in geophysical, environmental, biological and engineering sciences. A major component of this tool is a coupled chaotic dynamical system obtained by coupling two versions of the well-known Lorenz (1963) model with different time scales which differ by a certain time-scale factor. A tangent linear model and its adjoint are considered that correspond to a coupled chaotic system. The general idea of applying sensitivity measures (sensitivity functions) to coupled systems, emphasizing the data assimilation aspects, is explored as well by the forward sensitivity approach. For this purpose the set of sensitivity equations is derived from the nonlinear equations of the coupled dynamical system. To estimate the influence of model parameter uncertainties on the simulated state variables the relative error in the energy norm is used.展开更多
As the development of the current building activities continues to become mature, now the requirements on the indoor design activities will also be promoted. Compared with the interior design activities, the furniture...As the development of the current building activities continues to become mature, now the requirements on the indoor design activities will also be promoted. Compared with the interior design activities, the furniture is one of the important factors in the process of the interior decoration. The choice of the appropriate furniture not only can effectively improve the quality of the interior design activities, but also can fully meet the specific application needs of the people. This paper starts from the analysis of the specific requirements on the design and production of the modern furniture. And combined with the analysis of the specific characteristics and the connotation of the design styles of the furniture in the Ming Dynasty, the author further explores the specific influence of the design styles of the Ming Dynasty furniture on the modern furniture.展开更多
As the smart grid concepts are emphasized lately, the need to modernize the power engineering education is also well recognized. This paper presents a set of newly developed modeling, simulation and testing tools aime...As the smart grid concepts are emphasized lately, the need to modernize the power engineering education is also well recognized. This paper presents a set of newly developed modeling, simulation and testing tools aimed at better understanding of the design concept and related applications for protective relaying and substation automation solutions for the smart grid. Since the smart grid applications require integration of data from multiple IEDs (intelligent electronic devices), understanding properties of each IED type in detail, as well as their responses to the power system events is needed. In addition, understanding the communication requirements to perform data integration is also important. To illustrate how the mentioned smart grid issues may be taught, the following advanced teaching approaches are presented: (1) Use of modeling and simulation means to better understand interaction between the relays and power system; (2) Use of IED test facilities to better understand performance of physical devices used for protection, monitoring and control; (3) Utilization of communication network modeling tools to simulate the communication network within SAS (substation automation system). Examples showing the use of proposed techniques for teaching the fundamentals and applications are presented. The examples demonstrate the adequacy and efficiency of the proposed techniques.展开更多
The objectives of this paper are to (I) quantify the effects of age and other key factors on bridge deterioration rates, and (2) provide bridge managers with strategic forecasting tools. A model for forecasting su...The objectives of this paper are to (I) quantify the effects of age and other key factors on bridge deterioration rates, and (2) provide bridge managers with strategic forecasting tools. A model for forecasting substructure conditionisestimated from the National Bridge Inventory that includes the effects of bridge material, design load, structural type, operating rating, average daily traffic, water, and the state where the bridge is located. Bridge age is the quantitative independent variable. The relationship between age and substructure condition is a fourth-order polynomial. Some of the key findings are: (I) a bridge substructure is expected to lose from 0.52 to 0.11 rating points per decade as it ages from 10 to 70 years; (2) levels of deterioration increase significantly as the material changes from concrete, to steel, to timber; (3) slab bridges have lower levels of deterioration than other structures; (4) bridges that span water have lower condition ratings; (5) bridges with higher operating ratingshave higher condition ratings; and (6) substructure condition ratings vary significantly among states.展开更多
This article deals with the usage of building bricks as a didactic material for the development of architectural design. The building brick game chosen for analysis was the Arckit, since it is suitable for the archite...This article deals with the usage of building bricks as a didactic material for the development of architectural design. The building brick game chosen for analysis was the Arckit, since it is suitable for the architectural practice. It is estimated that this game can contribute to the design, representation and presentation of projects. In order to investigate in which aspects Arckit presents possibilities of applications, as well as limitations of use, the article approaches the importance of building bricks as a didactic tool and its use in the field of the architectural design process. From a literature review and an empirical experience, this article reports a qualitative research, where the applicability of the Arckit game was checked. Through a critical reflection based on that experience, it was possible to conclude that whereas its limitations to urban form and linked to the formal vocabulary that composes the grammar of these bricks, the Arckit building bricks represent in architecture a playful and experimental way to think and design, fomenting the creativity and the spatial perception, resulting in a particular experience that can make architecture better connected with dreams and joy.展开更多
基金supported by the Department of Scientific and Industrial Research(DSIR),India
文摘The present paper discusses the modeling of tool geometry effects on the friction stir aluminum welds using response surface methodology. The friction stir welding tools were designed with different shoulder and tool probe geometries based on a design matrix. The matrix for the tool designing was made for three types of tools, based on three types of probes, with three levels each for defining the shoulder surface type and probe profile geometries. Then, the effects of tool shoulder and probe geometries on friction stirred aluminum welds were experimentally investigated with respect to weld strength, weld cross section area, grain size of weld and grain size of thermo-mechanically affected zone. These effects were modeled using multiple and response surface regression analysis. The response surface regression modeling were found to be appropriate for defining the friction stir weldment characteristics.
文摘In marine application,marine grade steel is generally used for haul and superstructures.However,aluminum has also become a good choice due to its lightweight qualities,while rusting of aluminum is minimal compared to steel.In this paper a study on friction stir welding of aluminum alloys was presented.The present investigation deals with the effects of different friction stir welding tool geometries on mechanical strength and the microstructure properties of aluminum alloy welds.Three distinct tool geometries with different types of shoulder and tool probe profiles were used in the investigation according to the design matrix.The effects of each tool shoulder and probe geometry on the weld was evaluated.It was also observed that the friction stir weld tool geometry has a significant effect on the weldment reinforcement,microhardness,and weld strength.
基金the Pakistan Science Foundation(PSF)for providing financial support for the study
文摘A comprehensive landslide inventory and susceptibility maps are prerequisite for developing and implementing landslide mitigation strategies. Landslide susceptibility maps for the landslides prone regions in northern Pakistan are rarely available. The Hunza-Nagar valley in northern Pakistan is known for its frequent and devastating landslides. In this paper, we have developed a landslide inventory map for Hunza-Nagar valley by using the visual interpretation of the SPOT-5 satellite imagery and mapped a total of 172 landslides. The landslide inventory was subsequently divided into modelling and validation data sets. For the development of landslide susceptibility map seven discrete landslide causative factors were correlated with the landslide inventory map using weight of evidence and frequency ratio statistical models. Four different models of conditional independence were used for the selection of landslide causative factors. The produced landslides susceptibility maps were validated by the success rate and area under curves criteria. The prediction power of the models was also validated with the prediction rate curve. The validation results shows that the success rate curves of the weight of evidence and the frequency models are 82% and 79%, respectively. The prediction accuracy results obtained from this study are 84% for weight of evidence model and 80% for the frequency ratio model. Finally, the landslide susceptibility index maps were classified into five different varying susceptibility zones. The validation and prediction result indicates that the weight of evidence and frequency ratio model are reliable to produce an accurate landslide susceptibility map, which may be helpful for landslides management strategies.
文摘Monitoring of industrial plant performance and detection on flaws is important to the successful operation on industrial production units. Malfunctioning equipment can greatly impact plant performance by reducing the efficiency and increasing the production cost. Phenomenological equations cannot properly describe industrial processes. Thus, it is necessary to develop new equations for model industrial operations. The purpose of this study is to develop an empirical model for industrial demethanizer tower which is malfunctioning due to an error in the design in one of its plates. A nonlinear statistical model was designed to predict the pressure variation in the column, and consequently, the flooding conditions. This model was validated using industrial data to predict the maximum loads in the column.
文摘In past terrorist attacks, vehicle borne improvised explosive devices (VBIED) have been the primary manner of attacking buildings and infrastructures. Preventing unauthorized vehicles from approaching a protected area with anti-ram systems would maintain an established standoff distance against moving and stationary vehicles and consequently reduce blast and debris threats. This strategy has been considered the first line of defence against terrorists. Several types of anti-ram devices have been developed in accordance with U. S. Department of State K-rating criteria, for example, wedge barriers, rising beams, sliding/swing gates, and drop arms. However, these devices typically need a deep foundation for installation and can't be implemented into many locations where a depth of excavation is limited in order to protect utility lines of buildings and infrastructures. This paper presents a recent development of a series of shallow footing anti-ram bollard systems (SFABS) that can satisfy K-12 rating with only five-inch thick footing. A high-fidelity physics based finite element technique with a vehicle crash model is used for predicting anti-ram capacity and determining design parameters of the SFABS. Full-scale vehicle crash tests of the developed SFABS systems have been carried out to validate the design and analysis.
文摘The goal of this article is dual: first, introducing a new model of accident named STAMP (systems-theoretic accident modeling and processes); then applying the model to an innovative process for the treatment of contaminated substances and the re-use of treated substances. This article is a demonstration for a need of a new tool to take into account hazards and safety within socio-technical systems.
基金Supported by National Natural Science Foundation of China (No.50975200)
文摘The machining accuracy of workpiece is influenced by its orientation deviation, which is caused by the fixture-workpiece error. Based on the spatial coordinate theory, the orientation deviation of workpiece is measured by using an on-machine verification system, which can take into account the errors resulting from fixture manufacturing, installation and adjustment, location and clamping of workpiece. According to the least square method, the model of orientation deviation is built to determine the relationship between the theoretical and actual coordinate systems. The influence of orientation deviation on machining accuracy is quantified, and it is shown that the orientation deviation only affects the dimensional precision and position precision, rather than shape precision. In the experiment, the compensation processing of realtime errors was conducted, and the perpendicularity and inclination errors of the tetragonal part were reduced by 38.46% and 47.06%, respectively.
文摘In this paper, the authors present the development of a data modelling tool that visualizes the transformation process of an "Entity-Relationship" Diagram (ERD) into a relational database schema. The authors' focus is the design of a tool for educational purposes and its implementation on e-learning database course. The tool presents two stages of database design. The first stage is to draw ERD graphically and validate it. The drawing is done by a learner. Then at second stage, the system enables automatically transformation of ERD to relational database schema by using common rules. Thus, the learner could understand more easily how to apply the theoretical material. A detailed description of system functionalities and algorithm for the conversion are proposed. Finally, a user interface and usage aspects are exposed.
文摘A novel three-phase active power filter (APF) circuit with photovoltaic (PV) system to improve the quality of service and to reduce the capacity of energy storage capacitor is presented. The energy balance concept and sampling technique were used to simplify the calculation algorithm for the required utility source current and to control the voltage of the energy storage capacitor. The feasibility was verified by using the Pspice simulations and experiments. When the APF mode was used during non-operational period, not only the utilization rate, power factor and power quality could be improved, but also the capacity of energy storage capacitor could sparing. As the results, the advantages of the APF circuit are simplicity of control circuits, low cost, and good transient response.
基金supported by the National Natural Science Foundation of China (J0930005,30970350,31071959)
文摘With the development and decreasing cost of sequencing techniques, it is possible for scientists to conduct deeper research in phylogenomics. During the procedure of phylogenomic analysis, the mostimportant and vitalest step is orthology prediction, for that the prerequisite to phylogenetic reconstruction is that the genes being compared are orthologous. Here we briefly review the related concept of orthology anddifferent methods for orthology prediction. We also provide recommendations to give some advice for better selection of orthology prediction methods.
文摘Gear skiving is a promising gear cutting technology that can achieve a multiple faster internal gear cutting process than that of gear shaping. However,the kinematic system complicates skiving process,resulting in severe crater wear due to the intense variation of local cutting features. In particular,the negative rake angle near the cut-out is recognized as influential factor affecting the cutter wear progress,which needs the sophisticated simulation approach to elucidate the underlying cutting mechanism. In this research,the influence of the rake angle,e.g. top and side nominal rake angles of the cutter,is studied to further understand its role in the gear skiving process,for seeking the possibility of skiving process improvement by calculating the effective rake angle. As a result,the top and side rake angles of the cutter can both increase the effective rake angle when compared with the case of the none-rake angle,leading to an enhanced skiving process. This work provides fundamental knowledge of the rake angle for the gear skiving research,contributing to the optimization on the cutter parameters by considering the effective rake angle.
文摘Providing a decent housing is a major challenge for governments and development authorities in Jordan and Arab countries. Nevertheless, the growing number of population falling under poverty put more demand on low cost housing options. The goal of the research was to find ways of rationalizing the cost and determine the appropriate standards and models that achieve an acceptable equation between cost and performance, and that during design and construction phases. The study follows the method of investigation and analysis to get factors that reduce the cost of the house construction for poor families by means of the concept of standardization in traditional (popular) buildings system. The research confirms that the traditional system has many advantages that could strengthen towards development a low-cost building system by applying the principles of standardization through architectural, structural and electro-mechanical considerations of design. Research recommends taking on studies for low cost building system through comprehensive analytical study of local building experiences.
文摘End windings of generators are excited to vibrations due to electromagnetic forces which can cause severe damage and noise. To avoid this, it is important to predict the natural frequencies and modes of the end windings with finite elements. Due to the complex structure and unknown boundary conditions, the conventionally calculation of stator end windings has been very difficult and time consuming up to now. This paper describes the development of a full parameterized modeling tool, which allows a quick calculation of natural frequencies during the design phase of the generator. To keep the computing time low, it is important to find a way to get exact calculation results without detailed modeling of all pans. Additionally, special attention was paid to the active part, which has been replaced by spring-damper elements, and the determination of their stiffness via experimental modal analysis combined with finite element calculations.
文摘In this paper, a numerical modeling tool is described which can be used to explore various aspects of four dimensional variational data assimilation and parameter estimation arising in geophysical, environmental, biological and engineering sciences. A major component of this tool is a coupled chaotic dynamical system obtained by coupling two versions of the well-known Lorenz (1963) model with different time scales which differ by a certain time-scale factor. A tangent linear model and its adjoint are considered that correspond to a coupled chaotic system. The general idea of applying sensitivity measures (sensitivity functions) to coupled systems, emphasizing the data assimilation aspects, is explored as well by the forward sensitivity approach. For this purpose the set of sensitivity equations is derived from the nonlinear equations of the coupled dynamical system. To estimate the influence of model parameter uncertainties on the simulated state variables the relative error in the energy norm is used.
文摘As the development of the current building activities continues to become mature, now the requirements on the indoor design activities will also be promoted. Compared with the interior design activities, the furniture is one of the important factors in the process of the interior decoration. The choice of the appropriate furniture not only can effectively improve the quality of the interior design activities, but also can fully meet the specific application needs of the people. This paper starts from the analysis of the specific requirements on the design and production of the modern furniture. And combined with the analysis of the specific characteristics and the connotation of the design styles of the furniture in the Ming Dynasty, the author further explores the specific influence of the design styles of the Ming Dynasty furniture on the modern furniture.
文摘As the smart grid concepts are emphasized lately, the need to modernize the power engineering education is also well recognized. This paper presents a set of newly developed modeling, simulation and testing tools aimed at better understanding of the design concept and related applications for protective relaying and substation automation solutions for the smart grid. Since the smart grid applications require integration of data from multiple IEDs (intelligent electronic devices), understanding properties of each IED type in detail, as well as their responses to the power system events is needed. In addition, understanding the communication requirements to perform data integration is also important. To illustrate how the mentioned smart grid issues may be taught, the following advanced teaching approaches are presented: (1) Use of modeling and simulation means to better understand interaction between the relays and power system; (2) Use of IED test facilities to better understand performance of physical devices used for protection, monitoring and control; (3) Utilization of communication network modeling tools to simulate the communication network within SAS (substation automation system). Examples showing the use of proposed techniques for teaching the fundamentals and applications are presented. The examples demonstrate the adequacy and efficiency of the proposed techniques.
文摘The objectives of this paper are to (I) quantify the effects of age and other key factors on bridge deterioration rates, and (2) provide bridge managers with strategic forecasting tools. A model for forecasting substructure conditionisestimated from the National Bridge Inventory that includes the effects of bridge material, design load, structural type, operating rating, average daily traffic, water, and the state where the bridge is located. Bridge age is the quantitative independent variable. The relationship between age and substructure condition is a fourth-order polynomial. Some of the key findings are: (I) a bridge substructure is expected to lose from 0.52 to 0.11 rating points per decade as it ages from 10 to 70 years; (2) levels of deterioration increase significantly as the material changes from concrete, to steel, to timber; (3) slab bridges have lower levels of deterioration than other structures; (4) bridges that span water have lower condition ratings; (5) bridges with higher operating ratingshave higher condition ratings; and (6) substructure condition ratings vary significantly among states.
文摘This article deals with the usage of building bricks as a didactic material for the development of architectural design. The building brick game chosen for analysis was the Arckit, since it is suitable for the architectural practice. It is estimated that this game can contribute to the design, representation and presentation of projects. In order to investigate in which aspects Arckit presents possibilities of applications, as well as limitations of use, the article approaches the importance of building bricks as a didactic tool and its use in the field of the architectural design process. From a literature review and an empirical experience, this article reports a qualitative research, where the applicability of the Arckit game was checked. Through a critical reflection based on that experience, it was possible to conclude that whereas its limitations to urban form and linked to the formal vocabulary that composes the grammar of these bricks, the Arckit building bricks represent in architecture a playful and experimental way to think and design, fomenting the creativity and the spatial perception, resulting in a particular experience that can make architecture better connected with dreams and joy.