IDEF method

IDEF method-based simulation model design and development framework, The purpose of this study is to provide an IDEF method-based integrated framework for a business process simulation model to reduce the model development time by increasing the communication and knowledge reusability during a simulation project. In this framework, simulation requirements are collected by a function modeling method (IDEF0) and a process modeling method (IDEF3). Based on these requirements, a common data model is constructed using the IDEF1X method. From this reusable data model, multiple simulation models are automatically generated using a database-driven simulation model development approach. The framework is claimed to help both requirement collection and experimentation phases during a simulation project by improving system knowledge, model reusability, and maintainability through the systematic use of three descriptive IDEF methods and the features of the relational database technologies. A complex semiconductor fabrication case study was used as a testbed to evaluate and illustrate the concepts and the framework. Two different simulation software products were used to develop and control the semiconductor model from the same knowledge base. The case study empirically showed that this framework could help improve the simulation project processes by using IDEF-based descriptive models and the relational database technology. Authors also concluded that this framework could be easily applied to other analytical model generation by separating the logic from the data.

Simulation is one of the most widely used decision aid tools due to its power, flexibility, and robustness. Particularly the discrete event simulation (DES) can model and analyze the behavior of many real life processes such as business processes, supply chain, and manufacturing processes. However, as Ryan et al. pointed out (2006), the simulation modeling often becomes a heavy programming task with the essence of the system being modeled lost in the detailed programming codes. In this way, the essence of the system is visible only to the code developers. This could create several potential problems for those who are involved in a simulation project. For example, it may create a serious information reusability problem. A simulation model is an abstracted representation of a real system to solve specific problems. Hence the information collected and extracted from the real system should be systematically represented and stored for future reuse in the form of systematic descriptions and formats. It may also cause a communication problem between developers and users. Typically users are domain experts who want to experiment with the simulation model to solve domain specific problems. This task requires frequent parameter changes and modification of the model. However, the heavy codes add difficulty to the proper management of this task. If we consider a simulation model development as a project, and if we have a structured systematic tool to support the simulation project, we believe that these problems could be managed. Sheppard (1983) proposed a widely cited “40-40-20” simulation model development time rule which states that analyst’s time should be distributed as follows for a successful simulation project: (1) 40% to requirement collection phase such as problem formulation, project planning, conceptual model development, and data collection; (2) 20% to model translation phase; (3) 40% to experimentation phase such as model verification, validation, implementation, and interpretation. Hence, for successful implementation of any simulation project, it is particularly important to have a right approach to the requirement collection and the experimentation phases. Hence, this paper intends to provide an integrated framework for those two phases in a simulation project.

The process description methods could play an important role in the simulation requirement collection phase. Although many process design, analysis and modeling (DAM) methods have been developed, using these methods in isolation – non-methodological approach – often fails to capture critical system behaviors due to the complexities and component interactions within the system. A methodological approach – systematic usage of a suite of methods – has a greater chance of success at representing critical system behaviors since it can account for diverse aspects of DAM activities such as information, function, and process interactions by a systematic and integrated usage of methods. IDEF (Integrated DEFinition) is a suite of descriptive modeling methods within which several different modeling languages are defined to describe systems from different perspectives. First, since IDEF is a well defined suite, it is considered to be easier to implement a methodological approach with the IDEF suite rather than with a completely different set of methods. Second since it is a descriptive modeling method, it could easily abstract and capture the essence of the system. In a typical simulation project, a project team consists of many team members such as system analysts, developers and domain experts. The system analysts collect and refine requirements with assistance from domain experts. This is an iterative communication process among all members. The ‘descriptiveness’ of IDEF methods could make this communication process easier and smoother than any other non-descriptive methods. For these reasons, IDEF methods have been a continued research subject.

The first category of the IDEF method related research attempted to build a generic and conceptual descriptive model using IDEF suites in a specific domain (Ang et al., 1994; Zhang et al., 1996). Another category proposed a way to generate an analytical model from a specific IDEF model. For example, an IDEF3 method has been used to generate simulation models using Witness simulation software (KBSI, 1995) and using Arena software (Resenburg et al., 1995). Jeong et al. (2008) developed a scheme to integrate the IDEF3 with a general open queuing network where IDEF3 works as a knowledge repository. The third category employed multiple IDEF methods and attempts to reuse common system knowledge among the different IDEF methods. For example, Lingzhi et al. (1996) proposed a scheme to integrate IDEF1 with IDEF0 for a computer integrated manufacturing information system design. Chen et al. (2004) also proposed a scheme to develop the enhanced IDEF1 information model based on the IDEF0-based process information, which could serve as a base representation for an information model. This paper covers both the second and the third category together. It is an extension of Cho et al. (1999), KBSI (1995), and Chen et al. (2004) in that it attempts to provide an integrated framework of IDEF method-based simulation model design and development to help a successful simulation project.


Vehicle-based interactive management

Vehicle-based interactive management with multi-agent approach, Under the energy crisis and global warming, mass transportation becomes more important than before. The disadvantages of mass transportation, plus the high flexibility and efficiency of taxi and with the revolution of technology, electric-taxi is the better transportation choice for metropolis. On the other hand, among the many taxi service types, dial-a-ride (DAR) service system is the better way for passenger and taxi. However the electricity replenishing of electric-taxi is the biggest shortage and constraint for DAR operation system. In order to more effectively manage the electric-taxi DAR operation system and the lots of disadvantages of physical system and observe the behaviors and interactions of simulation system, multi-agent simulation technique is the most suitable simulation technique. Finally, we use virtual data as the input of simulation system and analyze the simulation result. We successfully obtain two performance measures: average waiting time and service rate. Result shows the average waiting time is only 3.93 seconds and the service rate (total transport passenger number / total passenger number) is 37.073%. So these two performance measures can support us to make management decisions. The multiagent oriented model put forward in this article is the subject of an application intended in the long term to supervise the user information system of an urban transport network.

To resist global warming, mass transportation plays an important role in metropolis (Government of Hong Kong, 2005). Public can travel by taking mass transportation rather than driving a car. In this way, public can reduce the CO2 generation and air pollution (GreenPartyTaiwan, 2007). In order to reduce the operation cost of mass transportation, Transportation Company has to abandon the flexibility and efficiency (Wu, 2006). However taxi just compensates the disadvantages of mass transportation, because it has the features of high flexibility and efficiency (GreenPartyTaiwan, 2007). So far, most of passengers stand beside road and wait for a taxi. In this condition, there are three disadvantages. First, passenger doesn’t know how long he/she has to wait until a taxi passes by. Secondly, passenger is not sure the coming taxi is free or not. Thirdly, taxi needs to go around and look for passenger. Hence the operation utility is too low so that causes the energy waste (Wu, 2005). Contrary, dial-a-ride (DAR) system is a good solution to solve this problem. In DAR system, passengers use wireless communication tool (mobile phone) to call for a pick-up and delivery service-to-service center (control center). Then, service center assigns an idle taxi to perform the task. Using this kind of service system, passenger doesn’t need to wait longer than before. And taxi driver can save the taxi energy. Hence, Dial-a-ride system is very important in taxi operation system (Wu, 2005). On the other hand, with the technological revolution of power, electric-taxi comes with the tide of fashion (Taiwan Environmental Information Center, 2009; BigSolar, 2005). Electric taxi means a taxi is driven by electricity. It has two advantages. First, for the earth, electric taxi can reduce the air pollution and global warming, because it can’t emit CO2 (the electric taxi we talk about is driven by pure electricity. The pure electricity means that it doesn’t emit CO2 and its source doesn’t involve any organic compound of carbon, like hydrogen-battery. For hydrogen-battery itself, its waste is “water” so it indeed can reduce the emission of CO2. (iCo2l, 2008)). Secondly, for taxi driver, electric-taxi can reduce the fuel cost, especially for oil, due to the cost of replenishing electricity is lower than gas or gasoline. Hence electric taxi is an important transportation for metropolises.

Contrary, electric-taxi also has disadvantage. The worst disadvantage in electric-taxi is the electricity that’s also the biggest limitation (Galus et al., 2009). During the electric-taxi traveling period, the electricity of taxi is decreasing. When the electricity of electric-taxi is not enough to do the next service, electric-taxi has to replenish its’ electricity in the electric station. During the replenishing period, electric-taxi can’t do any task and passenger still waits for service. Under this condition, that will cause the reduction of taxi company’s revenue and passenger satisfaction (GreenPartyTaiwan, 2007). However, revenue and passenger satisfaction are the most important performance measures for Taxi Company. So Electric-taxi Company has to propose some management policies to deal with the electric replenishing problem (Galus et al., 2009).

Hence how to manage the electric-taxi DAR operation system becomes a very important problem with management policies (GreenPartyTaiwan, 2007; Taiwan Environmental Information Center, 2009). In order to manage the electric-taxi DAR operation system, we have to construct an electric-taxi DAR operation simulation system. There is a lack in multi-agent transportation simulation, such as allowing cars move based on shortest path and dispatching operations. In fact, the traffic jams management is considerable for electric-taxi DAR operation system (Ezzedine et al., 2005; Kok & Lucassen, 2007; Lansdowne, 2006; Cubillos et al., 2008). So this paper takes into account the shortages of existing methods to reinforce our multi-agent simulation. On the other hand, due to the impracticable and costly weaknesses of physical system (Ali, 2006), multi-agent simulation technique is the most suitable simulation technique for our research.

The main purposes of this study are as follows: First purpose is to provide a series of management policies to manage the electric-taxi DAR operation system and analyze the phenomenon of simulation. Second purpose is to compensate the shortages of existing methods to reinforce our multi-agent simulation. The main contribution of this paper is that we successfully obtain the performance measures (average waiting time and service rate) to support the decision making for manager.

The rest of this paper is described as follows. Section 2 is the literature review. Section 3 introduces the electric-taxi DAR operation system. Section 4 creates the simulation system and describes the environment setting. Section 5 is to collect and analyze the data obtained from simulation. The last section will make a conclusion that includes the contributions of this research and describe the future work.


Complex system of a thermal power plant

Simulation modeling and analysis of a complex system of a thermal power plant, The present paper deals with the opportunities for the modeling of flue gas and air system of a thermal power plant by making the performance evaluation using probabilistic approach. The present system of thermal plant under study consists of four subsystems with three possible states: full working, reduced capacity working and failed. Failure and repair rates for all the subsystems are assumed to be constant. Formulation of the problem is carried out using Markov Birth-Death process using probabilistic approach and a transition diagram represents the operational behavior of the system. Interrelationship among the full working and reduced working has been developed. A probabilistic model has been developed, considering some assumptions. Data in feasible range are selected from a survey of thermal plant and the effect of each subsystem on the system availability is tabulated in the form of availability matrices, which provides various performance/availability levels for different combinations of failure and repair rates of all subsystems. Based upon various availability values obtained in availability matrices and graphs of failure/repair rates of different subsystems, performance and optimum values of failure/repair rates for maximum availability, of each subsystem is analyzed and then maintenance priorities are decided for all subsystems.

The thermal industry is becoming quite complex with a huge capital investment being incurred on process automation to enhance the reliability of system. Invariably, the proper maintenance of such systems and the frequency of maintenance are some of the issues that are gaining importance in industry. The production suffers due to failure of any intermediate system even for small interval of time. The cause of failure may be due to poor design, system complexity, poor maintenance, lack of communication and coordination, defective planning, lack of expertise/experience and scarcity of inventories. Thus, to run a process plant highly skilled/ experienced maintenance personnel are required. According to Kumar and Pandey (1993), for efficient functioning, it is essential that various systems of the plant remain in upstate as far as possible. However, during operation they are liable to fail in a random fashion. The failed subsystem can however be inducted back into service after repairs/replacements. The rate of failure of the subsystems in the particular system depends upon the operating conditions and repair policies used.

A probabilistic analysis of the system under given operative conditions is helpful in forecasting the equipment behavior which further helps in design to achieve minimum failure in the system i.e. to optimize the system working. A thermal power plant is a complex engineering system comprising of various systems: coal handling, steam generation, cooling water, crushing, ash handling, power generation, feed water, steam & water analysis system and flue gas & air system. These systems are connected in complex configuration. One of the most important functionaries of a thermal plant is flue gas & air system. The optimization of each system in relation to one another is imperative to make the plant profitable and viable for operation. Effectiveness of thermal power plant is mainly influenced by the availability, reliability and maintainability of the plant, and its capability to perform as expected. The present paper provides a probabilistic model to plant personnel to analyse system performance and to achieve the maximum availability. Some of the salient features of the proposed model are as follows:

  • The proposed model provides an integrated modeling and analysis framework for performance evaluation of the flue gas and air system of thermal plant
  • The proposed model combines a strong mathematical foundation with an intuitive graphical representation
  • The transition diagram represents the possible states of the system.

Development of GIS Interface Tool for GAMES Model

GIS Interface

Soil erosion is an important economic and environmental GIS Interface concern throughout the world. In order to assess soil erosion risk and conserve soil and water resources GIS Interface , soil erosion modeling at the watershed scale is imperative. The Guelph model for evaluating effects of Agricultural Management System on Erosion and Sedimentation (GAMES) is tailor-made for such applications; it, however, requires a significant amount of spatial information which needs to be pre-processed using a Geographic Information System (GIS). The GAMES model currently lacks any such automated tools. As such, the GAMES was loosely coupled to a GIS interface to manage the large spatial input data and to produce efficient cartographic representations of model output results. The developed interface tool was tested to simulate the Kettle Creek paired watershed in Southern Ontario, Canada. Result demonstrated that the GIS-assisted procedure increased the ability of the GAMES model in simulating such a spatially varied watershed and made the process more efficient and user-friendly. Furthermore, the quality of reporting and displaying resultant spatial output was also significantly improved. The developed GAMES interface could be applied to any watershed, and the enhancement could be used to assess soil erosion risk and conserve soil and water resources in an effective way.

Prior to the use of the computer-based hydrologic model and Geographic Information System (GIS) in hydrology and hydraulic projects, practitioners assembled a number of maps, imageries, stream network, and other relevant data from field surveys to perform manual preliminary hydrologic analyses such as catchment delineation [1][2]. These manual methods were very laborious, time-consuming and inefficient [3]. The advancement in GIS technology, digital spatial data, and efficient computers has precluded the need for many of these labor-intensive techniques [4]. Developments in the field of GIS helped users to organize all forms of geographically referenced data as layers and various GIS software/tools such as the ArcGIS [5], enabled hydrologists to pre-process, view and analyze project-specific digital elevation model (DEM), soil, land-use, and hydro-meteorological data spatially [6]. Besides, several hydrologic functions are in-built to perform some of the preliminary investigations which have reduced the level of approximation and subjectivity involved [7]. Use of GIS technology in any hydrology project significantly improved the quality, accuracy, and timeliness of the final product [8]. Furthermore, GIS greatly simplifies the model set up and improves model performance [9]. Additionally, the GIS advancements enabled users to handle a large amount of data in a short time frame.

Another critical component of GIS is an enhancement of the visual understanding of the spatial inputs and output results by managers, decision-makers and the public-at-large [10]. Changing the inputs of land use or introducing best management practices (BMPs) to compare the subsequent output can be very helpful to identify the problem and ease the decision-making process. Similarly, specialized interfaces when linked to a GIS application have increased the popularity and usability of spatially distributed hydrological models and led them to greater use and wide acceptance [11].

Developments of GIS interface for the hydraulic/hydrologic model started in 1975 when the HEC-1 model was integrated using a grid-based model. The resulted model was named as HEC-SAM. In this approach, the GIS software was simply used as a database to feed input data to the model [12]. There are several different approaches to integrating GIS with simulation models such as; the embedding method, loose coupling and tight coupling methods [13][14][15][16]. The loose coupling approach is the simplest as the GIS software and the hydrologic model exchange files, read some of its input data files from geo-database and produce resultant output in a format that allows processing and displays the results within the GIS software. This is a standard approach since it requires little or no modifications to model software [17][18]. From the successes of the past two decades, hydrological modelers have recognized the benefits of integration of GIS software and hydrological models [19][20]. The advancement in GIS technology and improved techniques for the integration of GIS with hydrological modeling has made hydrological models more efficient and user-friendly [21][22][23][33].

The Guelph model for evaluating Effects of Agricultural Management Systems on Erosion and Sedimentation (GAMES) [24], developed at University of Guelph, Guelph, Ontario, Canada, is seasonal event-based soil erosion and sediment yield simulation model for analyzing watershed management practices and effects on nonpoint source pollution changes [25]. However, it was not coupled with any GIS tool. As such, model inputs at user-specified spatial units were not automated which made the model difficult and inefficient to use in areas with high-resolution spatial maps. Furthermore, analyses of model outputs which could greatly be enhanced with the use of any GIS platform was hampered. The GAMES model thus needed a much-needed upgrade in this respect. In this research, a GIS interface modeling tool has been developed which involved two distinct phases. This is the first attempt of this kind specifically to the GAMES model and hence is a novel work. In the first phase, the GAMES model was loosely coupled to a GIS interface by developing a GAMES-GIS model in a GIS system. Then, a GAMES input data generator model was developed in Microsoft Excel using the Visual Basic code in order to convert the processed GIS data in a format compatible with the input format of the GAMES model.

In the second phase, the previous two steps process with many manual-based sub-processes were automated by creating a user-friendly computer interface using C# language. During these processes, no change was made in the source codes of the GAMES model. Hence, the main objective of this study is to present the development and evaluation of the GIS interface to the GAMES model in an agricultural watershed in Southern Ontario, Canada. This has resulted in enhancing the capabilities of GAMES model and making it more efficient and user-friendly.


The New Formula of Seismic Rigidity Method

Rigidity Method

This publication is a revised version of the Rigidity Method previous article. Seismic rigidity method despite its widespread use is the object of harsh criticism from scientists who oppose it to the methodology and results of seismological registration of earthquakes and microseisms. The article substantiates the original approach based on the solution of the direct problem of seismic microzonation for the model of real soil thickness. A new formula of the seismic rigidity method is proposed, taking into account the lithological, hydrogeological and spectral features of the soil mass, as well as the position of the new seismic scale of the SSI. The formula was tested on the example of the correct description of the features of macroseismic effects on the territory of Leninakan at the Spitak earthquake in 1988. Linear estimates according to the formula of seismic rigidity in the seismic microzoning area represent changes in seismic intensity in the most contrast way. It is shown that the real estimates of seismic intensity under strong seismic effects (by I > VII degree) will not exceed those given by the formula of the seismic rigidity method.

The seismic rigidity method (SRM) is historically one of the first instrumental methods of assessing the impact of soil properties on the parameters of seismic effects, which currently causes a contradictory attitude. On the one hand, it is the most frequently used method of seismic microzonation (SMZ); on the other hand, it is hardly possible to find in the arsenal of SMZ methods another method that is subjected to such fierce and diverse criticism. It should be noted that this criticism is not presented in the form of printed articles, but constantly arises in various discussions, in private opinions, etc., which only complicates public discussion. What to be considered and what to reject? This article attempts to understand this interesting and important from the practice point of view question. This publication is a revised version of the previous article [1] .

For the quantitative ratios, linking the soil properties with changes in seismic intensity S. V. Medvedev [2] was used the dependence of seismic intensity from three factors: the value of seismic rigidity―the product of elastic wave velocity on density, groundwater level and resonance phenomena in the thickness of the soil. Formally, this dependence is expressed by the relation: ΔIΣ=ΔIS+ΔIW+ΔIRΔIΣ=ΔIS+ΔIW+ΔIR , where consistently spelled out the above-mentioned factors. Consider each of the factors in more detail.


Compressive Behavior of Steel Members Reinforced by Patch Plate with Welding and Bonding

Steel Members

Repair and reinformcement of aged civil steel Steel Members structures is one of the important issues for maintaining and using them for a long term. For repair Steel Members and reinforcement of deteriorated civil steel structures due to fatigue and corrosion, patch plate reinforcement is widely applied. Bolting is generally used because of easy quality control and many construction achievements. However, bolting has downsides including holes made and weight increase. Welding is considered to overcome these demerits but in reality the application of welding is unsatisfactory due to the possibility of fatigue crack occurring from the welded part. In this study, a patch plate strengthening system of welded joint assisted with bonding has been proposed. The compressive behaviors of weld-bond jointed specimen were investigated by a series of experiments and FE analysis. It was confirmed that use of welding and bonding was effective to enhance compressive strength of specimen, due to better load-carrying capacity of patch plate compared with sole use of welding.

One of the major problems confronting steel civil infrastructures such as bridges is deterioration caused by fatigue and corrosion during their design life. The ageing steel bridges generally experience cyclic loading and exposure to severe environment, causing fatigue cracks and plate thickness reduction due to corrosion, which lead to the decrease of load-carrying capacity and even failure of structures. Considering the large cost of reconstruction, proper reinforcement and repair on deteriorated members are urgently required to ensure the structure safe and prolong the service time.

The conventional method of repairing or strengthening steel structures is to cut out and replace plating, or attach patch plate to the damaged portion of the member [1] . Replacement is often not feasible due to the difficulties of construction, high expense and long service interruption time; on the contrary, patch plate reinforcement is shown to be effective. The commonly used techniques for applying patch plate are bolting because of easy quality control and many construction achievements. However, increase of self-weight, drilling holes in sound part and weak point for corrosion are significant disadvantages of steel plate bolting. The application of welding has been considered to avoid these demerits, and the features of flexible operation, lightweight, good appearance and tightness make welding a popular joining method. Despite the fact that welding exhibits many strongpoints, in reality patch plate welding is not very satisfactory as it will change the material properties and may lead to fatigue crack occurring from welded part [2] .

The main causes of fatigue crack are stress concentration, residual stress, and high applied stress level; some treatments are usually performed to improve fatigue strength, such as TIG-dressing, grinding and hammer peening [3] . Recently adhesive bonding for fiber reinforced polymers (FRP) reinforcement has become a promising joining technology due to lightweight, uniform stress distribution and the elimination of local stress concentrations. As new material for structural rehabilitation in civil engineering, fiber reinforced polymers (FRP) has gained wide acceptance due to the advantages including high strength-to-weight ratios, excellent resistance to corrosion and environmental degradation [4] . However, there is also hesitancy in using bonding technology in structural components, since the long-term strength of adhesive bonding is probably affected by service temperature and environment limitation, such as chemical attacks and the presence of moisture.

As described above, each joining method for patch plate reinforcement has advantages and disadvantages. Therefore, a combination of welding and bonding has been examined for complementing the weak points of each joint method. Weld-bonding, an advanced hybrid joining technology, is generally used for thin plates (0.5 – 3 mm) by combining resistance spot welding with adhesive bonding [5] . In recent years it has attracted a great deal of attention of researchers and industries, as a result of the following superior properties of weld-bonded joint: 1) high static strength; 2) long term durability including fatigue performance; 3) improved corrosion resistance; 4) excellent appearance [6] [7] . Therefore, weld-bonding has been widely used in many fields such as production and assembly of aircraft, aviation and automobile.

For thick plates in civil steel structures, the possibility of combination of fillet welding and adhesive bonding has been put forward. As the most common type of weld for structural steel connections, fillet welding is naturally used for patch plate reinforcement. The concept of the proposed strengthening system is shown in Figure 1. In the case that the steel member reinforced by patch plate with welding is subjected to tensile or compressive force, the stress flows into patch plate from base plate though the welded edges, where stress concentration is anticipated to occur. After introducing adhesive bond material, the two plates are connected by inside bond and edge-side weld beads, the stress can be also transferred to patch plate by bond. Consequently, stress around welded part may be relieved and patch plate carrying load may be increased. Based on this concept, a series of experiments were carried out on patch plate joints by fillet welding assisted with bonding for investigating the static tensile strength and fatigue characteristics [8] [9] [10] [11] . The results of tensile tests on lap joint specimens revealed that the elasticity limit of weld-bond specimens was increased in comparison to that of weld (W) specimens. The 4-point bending fatigue experiment on patch plate joints by the combination of welding and bonding (WB specimens) and by only welding (W specimens) was performed. In comparison to W specimens, fatigue life of WB specimens was considerably increased when the fatigue cracks occurred at the weld root.

It has been confirmed that the combination of welding and bonding increase the elastic tensile strength and the fatigue strength of patch plate joints. However, a lot of structural components used in civil engineering are subjected to not only tensile and fatigue cyclic loads, but also compressive loads. It is unknown whether the weld-bonded patch plate reinforcement system is effective for the members subjected to compressive loads. Therefore, the compressive behavior of steel members reinforced by patch plate with welding and bonding is focused on in this study. To investigate the effectiveness of weld-bonded patch plate reinforcement system on compression members, a series of experiment and numerical analysis was carried out on box columns with patch plates by welding, bonding and combination of them. Firstly, the materials and specimens used in this study are explained in the 2nd Chapter. Especially, the material properties of bond subjected to weld heat input was examined. Furthermore, the heat affected bond region by welding was estimated in the specimen used in this study.


Experimental Investigation of Lime Treated Palm Kernel Shell

Kernel Shell

This experimental research is focused on the effect of concrete made by incorporating lime treated Palm Kernel Shell (PKS) & Sugarcane Bagasse Ash (SCBA) as partial replacements of coarse aggregates and Ordinary Portland Cement (OPC) respectively. An Kernel Shell experimental analysis for concrete grade 30 with a mix design ratio of 1:1.97:3.71 of cement:fine aggregates:coarse aggregates with a constant water to cement ratio of 0.5, was used. Physical tests such as workability on fresh concrete and water absorption on hardened concrete of each batch were carried out. Mechanical tests like compressive strength and split tensile strength were carried out on hardened concrete cubes (100 mm × 100 mm × 100 mm) and cylinders (100 mm × 200 mm) at 7 and 28 days. The experimental results obtained in this study indicate the possibility of using up 15% of lime treated PKS and 10% of SCBA for production of structural concrete.

Concrete is a manmade composite material consisting of cement, aggregates and water, which is used in civil engineering construction and is preferred all over the world. It is the second most consumed substance on earth after water [1] . According to [2] its usage is around 10 billion tons per year, which is equivalent to 1 ton per every living person and 1.7 tons per person in the United States. About 50% – 80% of its volume are aggregates that consist of natural crushed stones and sand. Due to the depletion of natural resources, worry is gaining place in the construction industry. In addition, since the bonding material in the concrete is cement, the high demand for this material has led to an increase in cost, making it the most expensive construction material. In view of the magnitude of these problems, combined with the problem of waste disposal, researchers decided to look for other ecological materials that could be used in the production of concrete.

The incorporation of agricultural waste material for concrete production can considerably reduce the cost incurred in buying coarse aggregate, which results in a potential reduction in the total cost of construction and will also reduce environment pollution [3] . Industrial actions produce significant quantities of non-biodegradables solid waste. Most of this waste consists of industrial waste (such as, sandpaper, chemical solvents, industrial by products, paints, paper products, metal and radioactive waste), municipal waste (such as plastics), and agricultural waste (natural fibers and such as palm kernel shell).

Palm kernel is the edible seed of the oil palm fruit. The fruit yields two distinct oils: palm oil derived from the outer parts of the fruit, and palm kernel oil derived from the kernel (FAO, 2002). Considerable amount of waste in form of PKS is generated during oil extraction. A PKS is an interesting alternative for combating problems of overexploitation of conventional aggregates in concrete whose global production increases regularly. The efforts of researchers are to achieve how to use that waste materials in concrete.

Ordinary Portland cement Type I (CEM I 42.5N) conforming to the requirements of [4] was used as a binding agent. According to [5] , the treatment of PKS with lime reduce the amount of it water absorption. Hence, the Palm Kernel Shell obtained from Uganda at Kalangala island was treated with lime to make the shell less permeable. The treatment was done by putting PKS in lime solution (40 g/l) for 2 hours follow by air drying to obtain saturated surface dried such that the water cement ratio was not affected. It met the requirement of [6] . The coarse and fine aggregate were locally obtained with nominal size of 20 mm for coarse aggregate and maximum size of 5 mm for fine aggregate. Both aggregates met the requirement of [6] . The Sugar Cane Bagasse Ash used was locally obtained from sugar manufacturing industry in Kakamega County (KENYA) and was prepared by sieving on 0.075 mm sieve. It met the requirement of [7] . The mix ratio of 1:1.97:3.71 for cement:fine aggregates:coarse aggregates with a constant water to cement ratio of 0.5 was used. The target grade of concrete was C30 and the specimens size used was cubes (100 mm × 100 mm × 100 mm) and cylinders (100 mm × 200 mm).


Monitoring and Identification of the Seismically Isolated

Seismically Isolated

This paper describes the installation and management of the monitoring system of the “Our Lady of Tears Shrine” in Syracuse, whose dome is an imposing r.c. and prestressed r.c. structure of about 22,000 ton that was seismically isolated by flat sliding devices with hysteretic dampers. The monitoring system, Seismically Isolated representing an upgrading and improvement of an old system never made working, has some innovative features, because it allows to manage with the same dedicated hardware and software both the slow (thermal variations, relative humidity, wind direction and velocity) and the fast acquisitions (dynamic vibrations by wind and earthquake). The monitoring system was inserted among those structures maintained and controlled by the Seismic Observatory of Structures of the National Department of Civil Protection. Some records of low magnitude earthquakes allowed to validate the correct behaviour of the whole structure, as well as to make a dynamic identification of the complex construction and to calibrate a detailed finite element model of the Sanctuary, thus predicting isolators’ behaviour under design earthquake.

In the last decades, a lot of existing or new constructions located all over the world have been object of seismic isolation interventions, aiming to passively control their structural behaviour. The efficacy of such interventions has been tested during recent real ground motions, as well as within laboratory and in-situ testing campaigns. This technology is now recognized as allowing structures to attain higher safety levels with respect to those achieved by conventional structures, even if modern seismic criteria are applied. Its large diffusion allows achieving a sensible reduction of seismic risk and is favoured by reliable codes and optimised computations [1] – [6] .

On the other hand, the new monitoring technologies have now a fundamental role in the structural field and have been progressing by supporting and helping the research through the use of more and more accurate and cheap instrumentations and methodologies: the structural monitoring represents an increasingly accessible reality, so that it can be considered one of the most important mean of decision support [7] [8] .

In its first applications, the need of a structural monitoring derived from the need to determine the safety conditions of historical constructions. At national level, during the last years of the twentieth century, the first case studies were relative to monumental buildings, as a consequence of a rediscovery of the Italian architectural heritage. Nowadays, the application field of the structural monitoring is extended to all the civil engineering constructions, from the transport infrastructures (bridges, dams, galleries, etc.) to the strategical buildings. Such a spread is due to multiple reasons: the technological progress in terms of sensors and data processing; the need to get more information on how a structure behaves, so reducing the uncertainties on its safety; the potentialities in the framework of the emergency management during catastrophic events; the local and/or global real-time control of the structure.

A structural monitoring system is able to acquire (in continuous, if necessary) the values assumed by some significant quantities, to warn appointed technicians on possible anomalies or the overcoming of defined threshold values, and the consequent automatic activation of alarm procedures and/or of suitable emergency measures. These technologies must allow to obtain all those information which points out a damage, an unexpected response or a change in the structural behaviour, and, if necessary, they must provide significant data concerning the environmental input. From the knowledge of these information derives the possibility to actuate eventual maintenance interventions, before the latters become very onerous in economic terms.

The static monitoring is addressed to observe the slowly variable quantities, as those related to thermal variations and meteorological phenomena: in spite of the greater simplicity with respect to the dynamic monitoring, it has huge potentialities, as happens when the data related to wind actions are acquired. The results of the static monitoring allow to the designer to get useful indications for a correct analysis of the structural behaviour.

The most important innovations have been achieved in the framework of the dynamic monitoring, directed to observe rapidly variable physical quantities. Such a kind of system can be designed in different ways, according to the desired objectives: the dynamic characterization of the monitored structure, the assessment of the time varying response of the structure, the transmission of a seismic excitation along a structure, etc.

Some years ago, the Italian National Seismic Service (SSN) started an important project, called Seismic Observatory of Structures (OSS), representing a complex network of structures properly selected on national scale, which include a continuous monitoring system able to provide useful experimental data and to transmit alarms in case of seismic events: bridges, public constructions as hospitals, city halls, churches, schools, isolated structures, etc. [9] . In the specific case of the isolated structures, the monitoring system allows to control the performance of the installed isolators. The OSS network is managed by a central computer, located in the SSN headquarters, where the recorded data flow in real-time: these data are automatically processed in a preliminary phase, and afterwards published on internet. Therefore, the OSS Project is able to provide to the academic and professional community all the data needed to evaluate the real response of a structure in exercise, to verify the performance of a control system installed on the monitored structure, etc. The goal of the OSS Project is that a monitoring system is able to return a picture of the structure, which is updated over time, and allows to determine an estimate of the resources needed to reduce the seismic risk. On the other hand, the OSS network provides the opportunity to compare the real constructions with the ideal project, whenever a check of the existing constructions’ safety is required according to the new codes.


Simulation of wind power

Simulation of wind power with front-end converter into interconnected grid system, In the growing electricity supply industry and open access market for electricity worldwide, renewable sources are getting added into the grid system. This affects the grid power quality. To assess the impact on grid due to wind energy integration, the knowledge of electrical characteristic of wind turbine and associated control equipments are required. The paper presents a simulation set-up for wind turbine in MATLAB / SIMULINK, with front end converter and interconnected system. The presented control scheme provides the wind power flow to the grid through a converter. The injected power in the system at the point of common coupling is ensured within the power quality norms.

Generation of electricity from wind is the fastest growing energy technology in the world. India is in the 4th rank and has a renewable energy gross potential installed of 7855 MW as on 2006.With increasing wind power production, it is important for grid owners, to predict the grid interaction of wind turbine in advance. Some grid simulation packages like power system simulator are used for power system behavioral studies. Models of new types of generating units, like wind turbine have to comply with the requirement. Considering wind turbine generating system operation in electric power system, it is necessary to utilize the steady state model for analysis, related to load flow, short circuit calculation, power quality assessments, etc. The electric utility grid system cannot accept connection of new generation plant without strict condition, due to the real power fluctuation and reactive power generation of wind plants. Therefore the penetration of wind power in grid implies taking care of power quality issues like voltage variation on grid, switching operation of wind turbine (Reid, 1996). Today grid connected wind turbines are equipped with power converter systems. The wind–generation system interconnected with power system as shown.

In modern wind turbine system, power is exchanged with grid through a dedicated power interface so as to improve the power quality norms and it should compensate for harmonics and reactive power in the system. The typical system is simulated for practical condition in power system and simulated results are presented. The proposed control keeps the unity power factor at the point of common coupling (PCC) and allows the system voltage be stable while compensating the reactive and real power demand of the load. The dynamics of the system and control action is simulated with the detail model of wind generator with front end converter system. This simulation is carried out in SIMULINK with power system block set


Keindahan Struktur Arsitektur

Keindahan Struktur Arsitektur

Keindahan Struktur dalam arsitektur terletak pada kinerja dan perilaku struktur bangunan dan elemen fasad sebagai salah satu komponennya. Bentuk struktural harus memiliki daya tarik estetika dan didorong oleh pertimbangan teknik. Desain elegan adalah desain yang muncul dari kreativitas teknik, memenuhi persyaratan efisiensi dan ekonomi, serta elegan.
Menurut Prof. David P. Billington dari Universitas Princeton, karya desain rekayasa struktur dapat dianggap sebagai ‘Seni Struktural’, hanya jika mereka mengejar semua 3 Es – Efisiensi, Ekonomi, dan Keanggunan. Istilah ini dikatakan diciptakan dalam bukunya tahun 1983 ‘The Tower and the Bridge’, dan muncul dari studi mendalamnya tentang berbagai struktur dan desainnya.

Performa struktural tingkat tertinggi dicapai saat mengungguli semua 3 E ini, di mana – ‘keanggunan’ berarti lebih dari sekadar estetika. Sebuah struktur tidak bisa menjadi karya seni struktural yang sukses tanpa menjadi karya desain teknik struktural yang berhasil – baik fungsional maupun aman.

Panggung arsitektur telah menyaksikan kreasi ‘Seni Struktural’ oleh banyak ahli desain dan teknik. Mereka memiliki sejarah arsitektur yang mempesona dengan kontribusi penting karena mereka menonjolkan struktur menjadi indah, namun berani.

John Augustus Roebling adalah seorang insinyur sipil Amerika kelahiran Jerman. Terkenal karena desain jembatan gantung tali kawatnya, dia telah mengambil beberapa langkah penting untuk membawa jembatan itu ke pusat perhatian.

Desain jembatan sekitar tahun 1880-an membutuhkan banyak pendekatan praktis dan teoretis, di mana Roebling merancang pendekatan gaya ekuilibrium, di mana kesetimbangan selalu terpenuhi tetapi kompatibilitas deformasi tidak diberlakukan. Di tengah-tengah itu, ia berhasil membuat jembatan monumental dan menjadi landmark!

Berada di New York City, seseorang tidak dapat mengabaikan Jembatan Brooklyn yang berdiri kokoh yang dirancang oleh Roebling. Ini adalah kabel hibrida / jembatan gantung dan merupakan salah satu jembatan tertua dari kedua jenis di Amerika Serikat. Pada tahun 1866, Jembatan Gantung John A. Roebling yang membentang di Sungai Ohio selesai dibangun, dan merupakan jembatan gantung terpanjang di dunia pada saat itu.
Salah satu tokoh perintis adalah arsitek Amerika keturunan Finlandia Eero Saarinen. Sebagai seorang desainer industri yang ulung, ia membentuk abad ke-20 dengan gaya neo-futuristiknya yang, pada saat itu, tampaknya muncul dari film-film fiksi ilmiah!

Putra dari arsitek terkenal Finlandia Eliel Saarinen, karyanya merayakan penggunaan kurva struktural yang sederhana, menyapu, melengkung atau rasionalisme seperti mesin.

Karya Saarinen yang paling terkenal adalah TWA Flight Center, yang menunjukkan ekspresionisme neofuturistiknya. Berfokus pada desain ini, orang dapat melihat bagaimana representasi estetika ‘bersayap’ telah dicapai dari keajaiban teknis cangkang beton.

Saarinen telah mahir menggabungkan struktur inovatif dengan pesona futuristik untuk generasi tersebut. Sebelum ke TWA Center, dia merancang Gateway Arch – sebuah monumen setinggi 630 kaki di St. Petersburg. Louis, di negara bagian Missouri, AS. Dibalut baja tahan karat dan dibangun dalam bentuk lengkungan catenary datar, ini adalah monumen buatan manusia tertinggi di Belahan Barat, gedung tertinggi yang dapat diakses di Missouri, dan lengkungan tertinggi di dunia. Saarinen bekerja sama dengan insinyur struktur Jerman-Amerika Hannskarl Bandel pada tahun 1947 untuk menciptakan keajaiban ini.

Eero Saarinen menciptakan desainnya melalui contoh-contoh bagus dari sinergi sempurna antara kreativitas arsitek dan pemikiran insinyur struktur.

Frei Paul Otto (Pemenang Hadiah Pritzker 2015): Otto adalah seorang arsitek dan insinyur struktur Jerman yang terkenal karena penggunaan struktur ringannya, terutama struktur tarik dan membran, termasuk atap Stadion Olimpiade di Munich untuk Olimpiade Musim Panas 1972. Ayah dan kakek Otto adalah pematung, dan sebagai murid muda, dia bekerja sebagai magang di stonemasonry selama liburan sekolah. Untuk hobinya, dia terbang dan mendesain pesawat layang – aktivitas ini memicu minatnya pada bagaimana selaput tipis yang direntangkan di atas bingkai cahaya dapat merespons gaya aerodinamis dan struktural.

Frei Otto memelopori penggunaan struktur modern, ringan, seperti tenda untuk banyak kegunaan. Dia tertarik kepada mereka sebagian karena nilai ekonomi dan ekologi mereka. Pada awal 1950-an, dia membangun model kompleks untuk menguji dan menyempurnakan bentuk tarik. Sepanjang karirnya, Otto selalu membangun model fisik untuk menentukan bentuk tubuh yang optimal dan menguji perilakunya. Insinyur di studionya adalah pengguna awal komputer untuk analisis struktural proyek Frei Otto, tetapi data input dasar untuk perhitungan ini berasal dari model pencarian bentuk fisik.

Félix Candela adalah seorang arsitek Spanyol-Meksiko yang dikenal karena peran pentingnya dalam pengembangan arsitektur dan teknik struktural Meksiko. Kontribusi utamanya pada arsitektur adalah pengembangan cangkang tipis yang terbuat dari beton bertulang, yang dikenal sebagai cascarones.

Kecerdasan visual Candela dan bakatnya untuk geometri dan trigonometri deskriptif diperhatikan selama tahun-tahun pembentukan studinya.

L’Oceanogràfic atau “The Oceanographic” adalah oseanarium yang terletak di sebelah timur kota Valencia, Spanyol, di mana habitat laut yang berbeda terwakili. Insinyur struktur Alberto Domingo dan Carlos Lázaro telah membantu Candela dalam perumusan desain struktural berulang yang menciptakan keanggunan terpadu.

Paviliun Quadracci yang ia buat pada tahun 2001 di The Milwaukee Art Center berisi brise-soleil “seperti sayap” yang dapat digerakkan yang terbuka hingga lebar sayap 217 kaki di siang hari, terlipat di atas gedung-gedung tinggi dan lengkungan di malam hari atau selama kondisi buruk. cuaca. Selama proses ini, kinerja bangunan diuji, dan itu menciptakan aura yang lebih elegan pada keseluruhan desain. Jembatan Reiman, juga dirancang oleh Calatrava, terhubung ke paviliun dan menyediakan akses pejalan kaki ke dan dari pusat kota Milwaukee.

The Turning Torso menandai masuknya Calatrava ke dalam struktur menara bertingkat tinggi. Ini adalah gedung pencakar langit tertinggi di Swedia dan negara-negara Nordik. Strukturnya secara estetis didasarkan pada patung yang disebut Twisting Torso, yaitu sepotong marmer putih berdasarkan bentuk manusia yang berputar, dibuat oleh Calatrava sendiri.

Untuk membawa ‘seni’ ini ke skala arsitektural seperti itu, dia melatih keterampilannya dan mengembangkan struktur kokoh dan tak tergoyahkan yang dibangun di atas sembilan segmen segi lima berlantai lima. Rotasi ini relatif satu sama lain saat struktur naik. Terakhir, segmen atas diputar 90 derajat searah jarum jam ke lantai dasar.

The Turning Torso adalah contoh bagus dari keanggunan yang melampaui estetika belaka, karena ‘putaran’ pelat lantai telah diakomodasi dengan baik oleh persyaratan fungsional bangunan.

Juga harus dicatat bahwa pekerjaan desain teknik struktural yang aman, fungsional dan berkinerja baik tidak boleh naik ke tingkat ‘seni struktural’ karena gagal menjadi elegan. Jawaban atas seberapa efisien arsitek dapat melakukan ini terletak pada – Desain parametrik.