Numerical Simulations

Industrial control systems are nowadays exposed in environments with rapid and unstable parameter changes and uses measuring equipments with critical output sensitivity. In the case of thermal gas analyzer, measurement errors are contributed by temperature, gas flow, and pressure. Error compensation is a key problem for these control systems. In recent years, it has been proven in the literature that artificial neural network (ANN) is a reliable and low cost solution to manage errors. Among all the algorithms of ANN, the back propagation is commonly used because of its simplicity and learning methodology is easy to realize. However, it has two notable drawbacks: (a) it is likely to run into local minimum, and (b) convergence is slow. Thermal conductivity gas analyzer often works in adverse surroundings, which requires fast and accurate measurements. Therefore, a strong learning network is needed. This paper proposes a novel thermal gas analyzer using adaptive neuro-fuzzy inference system. The effectiveness and validity of the proposed method is verified by simulation studies using MATLAB. Fuzzy membership rules are created to allow regulation of learning parameters. Further, the fuzzy adaptive network model is constructed to train large data samples while the high precision compensation of sensor error is realized by the improved flow. Simulation results reveal that the convergence speed and output accuracy is improved and the learning parameters in thermal gas analyzer are automatically corrected by the proposed method in comparison with the back propagation algorithm of artificial neural network.

Saltation is the dominant mode of the sediment transport in rivers. Several factors such as the viscosity of the carrier liquid, size of the moving particles, the roughness of the river bed, initial conditions of the numerical procedure (i.e. lift-off angles and velocities, and initial angular velocity), and the accuracy of the empirical features of the governing equations (e.g. drag and lift coefficients) have sig¬ nificant effects on the accuracy of the numerical simulation of the sediment particle saltation. Numerous studies were considered various aspects of the numerical simulation of the sediment saltation, although no significant research has been conducted on how the simultaneous variations of the parameters of the model affect the accuracy of the simulation results. Therefore, in the present study, a systematic sensitivity analysis of some of the aforementioned input factors was performed through executing over 1,000 numer¬ ical experiments for single-step saltation. An accurate particle saltation model was developed for the range of sand to gravel in the Lagrangian approach. The model, which was verified using available experimental data, includes the non-linear drag force, the shear lift force, Magnus force, the buoyancy force, the added mass force, the history force and torque. The results indicated that the rankings of the importance of the input parameter errors on the output results for sand grain are: the viscosity of the carrier liquid, lift-off angle and velocity, the roughness of the river bed and initial angular velocity, whereas this rankings for gravel grain are: the roughness of the river bed, lift-off angle, initial angular velocity, lift-off velocity and the viscosity of the carrier liquid.

Mathematical Modelling has a long history in developmental biology. Advances in experimental techniques and computational algorithms now permit the development of increasingly more realistic models of organogenesis. In particular, 3D geometries of developing organs have recently become available. In this paper, we show how to use image-based data for simulations of organogenesis in COMSOL Multiphysics. As an example, we use limb bud development, a classical model system in mouse developmental biology. We discuss how embryonic geometries with several subdomains can be read into COMSOL using the Matlab LiveLink, and how these can be used to simulate models on growing embryonic domains. The ALE method is used to solve signaling models even on strongly deforming domains.

In this paper, a physics-based model for a snare drum will be discussed, along with its finite difference simulation. The interactions between a mallet and the membrane and between the snares and the membrane will be described as perfectly elastic collisions. A novel numerical scheme for the implementation of collisions will be presented, which allows a complete energy analysis for the whole system. Viscothermal losses will be added to the equation for the 3D wave propagation. Results from simulations and sound examples will be presented.

A generalized macroscopic representation of electrical steels used in transformer manufacturing industry is developed. The proposed representation is specifically formulated for integration in the finite element method. Usage of the specific technique enables the accurate evaluation of electromagnetic field distribution of transformer cores under heavily saturated conditions. Advantages over conventional techniques include numerical stability, numerical accuracy, and reduction of iterations of the Newton–Raphson method.

In this paper a robust three-dimensional (3D) finite element (FE) anisotropy model is introduced based on a particular scalar potential formulation. The specific 3D FE model is suitable for the accurate evaluation of the peak flux density distribution and no load loss of one-phase and three-phase wound core distribution transformers. The accuracy of the proposed 3D FE anisotropy model is validated by local flux density and no load loss measurements.

The paper presents a modeling approach related to High Velocity Oxygen-Fuel (HVOF), and similar spraying processes based on combustion. The model and related software allow analysis of temperature and velocity distributions of combustion products and spraying particles inside an HVOF torch as well as downstream of a barrel exit. Interaction of the two-phase spray jet and a substrate is a part of the model too. The main input parameters are the following: type of a fuel, fuel and oxygen flow rates, the torch thermal efficiency, throat diameter, barrel length and diameter, geometry of the expansion, position and diameter of powder injectors, composition and size of the spraying particles, and spraying distance.. A capability of the software is illustrated by the results of calculations regarding the influence of some of the main input parameters on particle temperature and velocity. The results of the modeling are in a good agreement with the published experimental data. The modeling has been successfully used for a modification of a HVOF torch and an improvement of its performance.

Collisions play an important role in musical acoustics. Extensive study has already been performed on this subject for a number of systems, with notable examples being the hammer-string collision in the piano, and the mallet- membrane collision relevant in drums.
This paper uses experiments and modelling to investigate collisions in the snare drum. This is an interesting percussion instrument, as two collision mechanisms feature prominently. Initial excitation usually results from collision between a striker, such as a mallet, and the upper (‘batter’) membrane. Ensuing membrane and cavity vibrations then give rise to secondary collisions between the lower membrane and a number of metal wires (‘snares’) that are tensioned across it. These collisions are crucial for the sound qualities of the snare drum, and so a proper understanding of their nature is essential for accurate sound synthesis models.
In this preliminary paper, a simplified experimental setup will be studied, consisting of a drumskin with a single snare stretched across it. The system can be excited either by plucking the string, or by striking the membrane with a mallet. A setup involving a high speed camera and a laser vibrometer will allow the motion of the snare and membrane to be captured.
Experimental results will be used in comparison with a novel numerical model that describes both the mallet-membrane and string-membrane collisions. The interactions are described by a non-linear force expressed in terms of a power law, similar to one used in the past for modelling the hammer-string collision in pianos.

Die Planung und Ausführung von tiefen Baugruben in weichen Böden im innerstädtischen Bereich ist für alle Beteiligten eine große Herausforderung. In diesem Beitrag wird die Herstellung einer 8 m tiefen Baugrube mit unmittelbarer Nachbarbebauung in Konstanz vorgestellt. Hierzu werden umfangreiche Messergebnisse gezeigt, die im Rahmen der bei Baugruben in weichen Böden unverzichtbaren Beobachtungsmethode erfasst wurden, und mit den Ergebnissen einer numerischen Analyse unter Berücksichtigung der räumlichen und zeitabhängigen Effekte verglichen. Darüber hinaus werden die erforderlichen Nachweise für den Grenzzustand der Tragfähigkeit unter Berücksichtigung der komplexen Baugrund-Tragwerk-Interaktion präsentiert. Insbesondere wird ein modifizierter Ansatz zur Berechnung der Aufbruchsicherheit einer verankerten Baugrubensohle nach den Vorgaben des Eurocodes EC7-1 in Anlehnung an die Empfehlungen des Arbeitskreises „Baugruben“ der Deutschen Gesellschaft für Geotechnik vorgestellt.
Die Baugrube mit einem annähernd quadratischen Grundriss wurde im Jahr 2008 in weich-breiigem Seeton mit zwei Untergeschossen hergestellt. Als Verbauwand wurde eine eingepresste Spundwand verwendet, die in einer Höhe von –1,80 m durch einen oberen Aussteifungsring aus einer Gurtung mit diagonalen Ecksteifen und mit einer abschnittweise hergestellten Unterbetonsohle in einer Tiefe von –7,80 m ausgesteift wurde. Die räumlichen Einflüsse der Baugrund-Tragwerk-Interaktion, die für dieses Projekt durch den Einbau einer rautenförmigen oberen und unteren Aussteifung und den abschnittweisen Einbau der Betonsohle bestimmt wurden, konnten in einer zweidimensionalen numerischen Analyse mit Mobilisierungsfaktoren und unter Berücksichtigung der spannungspfadabhängigen Steifigkeit des Seetons zutreffend erfasst werden.
Dieses Ausführungsbeispiel einer tiefen Baugrube in weichen Böden verdeutlicht besonders die Wichtigkeit eines umfangreichen begleitenden Messprogramms im Hinblick auf die Anwendungsgrenzen der Finiten Elemente Methode bei Verwendung derzeit kommerziell verfügbarer höherwertigerer Stoffgesetze. In dem Beitrag wird darüber hinaus eine Methode zur Berücksichtigung der spannungspfadabhängigen Steifigkeit von weichen Böden vorgestellt.

Atmospheric methane is one of the main greenhouse gases which contribute significantly to increase the burden of global warming. The production of rice paddies and livestock farming are the major sources of methane emissions in the atmosphere. The control of methane emissions using some efficient mitigation options is crucial to lower the concentration of methane in the atmosphere so that the adverse effects of global warming can be reduced to some extent. In this paper, a nonlinear mathematical model is proposed to study the effects of mitigation options on abatement of methane discharged by rice paddies and livestock populations in the atmosphere. In the modeling process, four nonlinearly interacting variables namely, the cumulative density of rice paddies, the cumulative density of livestock populations, the atmospheric concentration of methane and the cumulative density of mitigation options are considered. The cumulative density of mitigation options is assumed to be proportional to the increased level of atmospheric methane concentration from its equilibrium. The proposed nonlinear model is analyzed using the stability theory of differential equations and computer simulations. The study shows that without implementation of mitigation options, the concentration of methane in the atmosphere increases continuously with increase in the rates of its emissions by rice paddies and livestock populations. This increase in the atmospheric methane can be reduced considerably by efficient management of mitigation options. The increase in the implementation rate coefficient of various mitigation options and depletion rate coefficient due to net effectiveness of mitigation options further reduces the atmospheric methane concentration. The numerical simulation of the model confirms the analytical findings.

This paper uses CFD code to simulate the 3D flow and local scouring around bridge piers. The 3D Navier-Stokes equations are solved with Finite Difference Method and the RNG κ-ε turbulence model is selected and the bed load model is based on the excess bed shear stress applied by the flowing water. The free surfaces are modeled with the Volume of Fluid (VOF) technique. Simulated results include scour depth around six different shapes of bridge piers and velocity distribution around piers. The calculations of velocity distribution and scour depth are conducted based on previously laboratory experiments. Comparison of the results between the numerical model and experimental model indicates about (5.1%-9.8%) and (1.8%-6.1%) ranged errors for prediction scour depth and maximum velocity, respectively, is considered a good results. The CFD code provides an economic way to predict potential results. Also, it seen that the CFD code is an effective tool for analyzing free surface flows and scour depth around bridge piers.

Excavations in soft soils in particular in urban environments with adjacent neighbouring buildings are always subjected to deformations that are not fully avoidable. The soil-structureinteraction of excavations in soft soils is dependent on many factors. A classification of these factors that influence the deformation behaviour depending on the degree of designer interference dealt with in chapter 2. The focus of this research work is to examine the uncontrollable factors that affect the deformation behaviour based on the above classification. The ground conditions, in general, and the material properties of the soft soils in particular, are responsible primarily for the deformation behaviour. For this reason, the material behaviour of soft soils has been scientifically studied using experimental and numeric methods taking into account characteristic stress conditions that arise during excavation. The factors that are under designer control, e.g. support system and its stiffness, the factors that are partially under designer control, such as the method and quality of support construction, and the construction period are also analysed taking into account the time and stress path dependent material behaviour of the soil.
The research work is organised in three core areas which are developed one up on the other. Using excavation model tests, a numerical parameter study of three idealized excavations, and stress path controlled element tests, the above mentioned factors are examined. The time and stress path dependent material behaviour can be generally analysed and validated using a numerical analysis of three practical case studies based on a method that considers the stress path dependent stiffness. This method is devolped and explained within this thesis. Two of the practical projects had been accompanied by the author in the framework of this research work during the construction phase and one starting from the design phase.

Implementing an effective disaster management, community-based disaster management (CBDM) has become increasingly important in societies facing complex and uncertain disaster risks. CBDM emphasizes community self-reliance, raising awareness of vulnerability and root causes of disasters and developing practical program-solving skills. It is also widely recognized that community-based flood risk communication among residents, regional communities, and administrative authorities is central to effective flood risk management. A clear communication of flood risk ensures the appropriate and effective steps to reduce and mitigate the risk in community-based flood risk management. Flood hazard maps are
also recognized as useful instruments for flood risk management in many other countries. In the case of a
flash flood, it is crucial to examine the evacuation timing and time-space distributions both of flood risk and safety evacuation routs in the community levels. However, very little work is currently available to investigate these issues in the conventional flood hazard maps. This lack of the studies is troubling in implementing the effective community-based flood risk management. The purpose of this study is to investigate
an integrated flood evacuation simulator taking into account the time-space distributions both of flood risk and safety evacuation routs in the community levels. Two-dimensional flood simulations were conducted using an unstructured grid model to consider the detailed land-use in the community level. The flood evacuation simulations using the multi-agent model were also performed to examine the evacuation timing and proper location planning of evacuation refuges. The proposed evacuation simulator would be recognized the useful tools for disaster prevention planning in community levels. This simulator also can be used for disaster education, evacuation planning and training for both the individual and community
levels.
Key Words : Community-based Flood Risk Management, Evacuation, Integrated Model, Hazard Map

The present Ph.D. dissertation deals with the finite element analysis of the heat transfer processes in double U-tube Borehole Heat Exchangers, called BHEs. As the main outline of this study, it can be pointed out to the analysis of the working fluid temperature distribution, proposing correlations to determine the mean fluid temperature, and the analysis of the thermal resistance and effects of the temperature distribution on it, for double U-tube BHEs. In the evaluation of thermal response tests (TRTs), in the design of the BHE fields, and in the dynamic simulation of ground-coupled heat pumps (GCHPs), the mean temperature Tm of the working fluid in a BHE, is usually approximated by the arithmetic mean of inlet and outlet temperatures. In TRTs, this approximation causes an overestimation of the thermal resistance of the heat exchanger. In the dynamic simulation of GCHPs, this approximation introduces an error in the evaluation of the outlet temperature from the ground heat exchangers. In the present thesis, by means of 3D finite element simulations, firstly, the analysis of the fluid temperature distribution is carried out, then, correlations are proposed to determine the mean fluid temperature, for double U-tube BHEs. Tables of a dimensionless coefficient are provided that allows an immediate evaluation of Tm in any working condition, with reference to double U-BHEs with a typical geometry. These tables allow a more accurate estimation of the borehole thermal resistance by TRTs and a more accurate evaluation of the outlet temperature in dynamic simulations of GCHP systems. Criteria for the extension of the results to other geometries are also provided. In addition, the effects of the surface temperature distribution on the thermal resistance of a double U-tube BHE are investigated. It is shown that the thermal resistance of a BHE cross section (2D) is not influenced by the bulk-temperature difference between pairs of tubes, but is influenced by the thermal conductivity of the ground when the shank spacing is high. Then it is shown that, if the real mean values of the bulk fluid temperature and of the BHE external surface are considered, the 3D thermal resistance of the BHE coincides with the thermal resistance of a BHE cross section, provided that the latter is invariant along the BHE. Eventually, the difference between the BHE thermal resistance (2D or 3D) and the effective BHE thermal resistance, defined by replacing the real mean temperature of the fluid with the average of inlet and outlet temperatures, is evaluated in relevant cases.

In this paper, hydrodynamic effects of ventral pleats covering mouth and bell parts of humpback whales are studied for the first time. In this regard, turbulent flows over a simplified model of the animal body as a half grooved ellipsoid are numerically simulated using Lam-Bremhorst low Reynolds turbulence model resolving to the wall at different angles of attack and sideslip. The results show that presence of the ventral pleats leads to formation of low speed strips and shear layer/vortex on the bottom surface of the animal, which in turn results in a relatively higher pressure region on the bell and higher drag coefficient compared to a case without grooves. In this way, pleats generate lift and contribute to buoyancy force and also increase tendency of flow separation. The results also depict superior performance of the grooved body at sideslip angles. Furthermore, results of cavitating flow simulation over the grooved model showed a suppression of lift generation contribution of the ventral grooved surface in cavitating conditions, the most similar situations to bubbly flows experienced by humpback whales in bubble net fishing environment.

Interaction between an animal and its habitat is one of the crucial factors in the evolution process. In aquatic environments, marine species have developed some unique morphological features with hydrodynamic consequences to overcome necessity of life over the course of million years. In this paper, hydrodynamic effects of the longitudinal-dorsal ridges covering the upper-lateral sides of whale shark's body as a prominent eidonomic characteristic of these species are studied with the aid of computational fluid dynamics (CFD). In this regard, flow physics of the problem is numerically simulated at high Reynolds number, i.e. 1.4*10^7 corresponding to the swimming of a 10 meter-whale shark at its average speed, i.e. 5km / h, using Lam-Bremhorst turbulence model. The results indicate that presence of the longitudinal ridges leads to formation of streamwise vortices which delays flow separation on the body and modifies hydrodynamic characteristics of the whale shark swimming. At sideslip angles, flow simulation results show that the ridges noticeably contribute to the 'sinking feeling' of the animal. Furthermore, spectral analysis of the unsteady simulation results in start-up phase of the whale shark's tail beating in a quiescent flow environment depict that these morphological features uniformize energy content of the vortical structures originating from the tail/caudal peduncle (not caudal fin) via suppressing of its energy peaks.

Bidang keilmuan rekayasa teknik sipil diperlukan untuk perencanaan pembangunan prasarana dan sarana fisik yang bermutu bagi masyarakat. Untuk menunjang kesuksesannya, selain aspek
sains dan teknologi, ternyata aspek pengalaman para pelaksana sangat berperan. Adapun yang dimaksud dengan pengalaman kadang bersifat subyektif, bisa berbeda-beda antara satu orang dengan yang lainnya. Karena bidang tersebut menyangkut kepentingan masyarakat luas, maka
untuk mengatur aspek-aspek di atas agar dapat dikendalikan, perlu aturan yang mendukung. Aturan itu umum disebut sebagai code atau standard atau spesifikasi teknis tertulis yang berkekuatan hukum. Isinya berisi petunjuk bagaimana menghasilkan standar mutu keamanan minimal yang harus diberikan pada suatu bangunan yang direncanakan dan dikerjakan. Makalah akan membahas peran pentingnya penguasaan code bagi kemajuan pembelajaran rekayasa dan mutu pelaksanaan konstruksi Indonesia, khususnya struktur baja. Pembahasan ini diperlukan dalam menyambut berlakunya SNI baja terbaru, yaitu SNI 1729:2015, yang merupakan adopsi penuh dari AISC (2010), code struktur baja Amerika dan Kanada. Sekaligus membahas materi baru code tersebut yang diperlukan. Harapannya dapat dipahami hal-hal
yang diperlukan dalam menguasai dan mengaplikasikan code tersebut secara benar.

This Guidelines, also published with the original English name of “How to ‘Bridge the Gap’ between
University and Business”, has been developed inside the project “ADRIA-HUB- Bridge technical differences
and social suspicions contributing to transform the Adriatic area in a stable hub for a sustainable
technological development” and financed by the EU IPA-ADRIATIC Cross Border Cooperation Programme
2007-2013.

The purpose of this program is to implement Galerkin method over the entire domain for solving the following general 2nd order, homogeneous, Boundary Value problem (BVP) with constant coefficients. Numerical results are then compared with the exact solution.

In this paper, inspired by the external morphology of a manta ray (Mobula alfredi), four chimerical wing planforms are designed to assess its gliding performance. The planforms possess an arbitrary combination of extra hydrodynamic features including tubercles at the leading edge (L.E.) and trailing edge (T.E.) inspired by humpback whale's flippers and flukes, respectively, as well as longitudinal ridges inspired by whale shark's eidonomy. In addition, another planform is designed to investigate the possible effects of manta ray's injuries (geometric deficiency) generated by predator's attacks or boat strikes on its locomotion (gliding) performance. In this regard, turbulent flow physics involved in the problem is numerically simulated at different angles of attack (AoA). High Reynolds number, 10^6, corresponding to the swimming of a juvenile manta ray at an average speed equals 1 m/s. The results show that the manta ray-inspired planform with L.E. undulations exhibits a superior performance at high AoAs than its other counterpart variants. In addition, the results demonstrate that injuries on the manta ray's body can noticeably modify hydrodynamics and, as a result corresponding hydrodynamical forces and moments acting on the swimming animal in the gliding phase.

A numerical simulation method based on the potential flow model has been developed for the prediction of the cavitation characteristics of centrifugal pumps. This study deals with cavitation modeling beyond inception, i.e. the formation of the first bubble. Cavitation inception depends on the inlet stagnation pressure. For inlet pressures
lower than the inception value a cavitation sheet will develop, which influences the hydraulic performance of the pump. Furthermore, the length of the sheet shows a strong correlation with the life span of the pump. This indicates the importance of predicting the cavitation sheet.

The losses in European Union distribution transformers are estimated at about 33 TW · h/year, whereas reactive power and harmonic losses add a further 5 TW · h/year. The reduction of distribution transformer no-load loss is particularly important as the ratio of no-load to load losses is nearly three. In this paper, the no load operation of wound-core transformers under sinusoidal and distorted supply-voltage conditions is investigated. For that purpose, a 2-D nonlinear transient finite-element analysis taking into account hysteresis has been developed. The hysteresis model is based on a modified Jiles–Atherton representation, and the proposed analysis is compared to experimental data.

A novel alteration to the Cauchy–Kowalevski procedure is here presented to obtain essentially monotonic solutions
for multidimensional flows. It is argued that this can be accomplished by splitting the cross-derivative terms among
the several dimensions, such that the coefficient of the cross derivatives remains small compared to the coefficient of
the normal derivatives. The approach naturally lends itself to extending the Roe flux difference splitting scheme to
multiple dimensions and is advantaged over previous Cauchy–Kowalevski-based methods by yielding a solution free
of spurious oscillations in the vicinity of oblique shock waves. Several test cases ranging from low-speed subsonic flows
in channels to hypersonic flows over ramp injectors indicate that the proposed genuinely multidimensional method
generally achieves a twofold or more increase in resolution along each dimension over the dimensionally split Roe
scheme while retaining its appealing attributes: the scheme has a compact three-node-bandwidth stencil, is a finite
volume flux function, yields essentially monotonic solutions, introduces minimal dissipation within viscous layers, and
is written in general matrix form. Although the method proposed is first-order accurate, it offers a resolution as high
or higher than the dimensionally split second-order total-variation-diminishing schemes for many problems of
interest and is expected to surpass significantly the latter when extended to second-order accuracy.

A prototype low capacity (10 kW) single stage Li–Br absorption heat pump (AHP), suitable for residential and small building applications has been developed as a collaborative result between various European research institutes and industries. The primary heat source for the AHP is supplied from flat plate solar collectors and the hot/chilled water from the unit is delivered to a floor heating/cooling system. In this paper we present the simulation results and an overview of the performance assessment of the complete system. The calculations were performed for two building types (high and low thermal mass), three climatic conditions, with different types of solar collectors and hot water storage tank sizes and different control systems for the operation of the installation. The simulations were performed using the thermal simulation code TRNSYS. The estimated energy savings against a conventional cooling system using a compression type heat pump was found to be in the range of 20–27%.

Majority of  engineering  colleges, universities and
the technical institutions are undertaking all initiatives to stay competitive. Efforts are exerted to continuously improve the curriculum in order to provide quality and relevant education for the students in response to global call for outcomes-based education. This paper presents the procedures, techniques, methods,  and advantages of using Altium Designer software in teaching electronic circuits. Altium Designer is a schematic capture, simulation, and PCB design software, dedicated to analyzing electronic circuits which is based on interconnected icons of electronic components. The approach makes it easier for the students to visualize the system they are attempting to design, model, and study. Likewise, it makes debugging and error correction simpler. Moreover, an example has been provided  also  to show how to use  the software for teaching and research in electronic circuits.

ABSTRAK
Produk dari numerical weather prediction (NWP) mengandung nilai ketidakpastian karena adanya variasi galat sehingga memiliki kecenderungan pengurangan skill seiring bertambahnya proyeksi waktu prakiraan, dimana sebuah model akan bergantung pada beberapa parameter salah satunya adalah initial condition, sehingga diperlukan proyeksi dari produk model NWP terhadap perbedaan reinisialisasinya. Adapun data yang digunakan adalah data FNL, data observasi format bufr dan data observasi STAMET Nabire. Dalam penelitian ini digunakan metode Ensemble Mean untuk melihat bagaimana proyeksi model dalam melakukan simulasi hujan lebat di Kabupaten Nabire. Nilai ensemble mean menunjukkan pola fluktuatif yang mengikuti pola persebaran nilai observasinya dibandingkan nilai inisialisasinya walaupun masih memiliki nilai simpangan di setiap parameternya Simulasi hujan lebat dengan ensemble mean dari beberapa inisialisasi menunjukkan pola yang sesuai dengan pola hasil observasi namun memilki nilai yang cenderung underestimate. Data keluaran model dengan asimilasi membutuhkan waktu spin up yang relatif lebih singkat dibanding non asimilasi .
Key words : NWP, Ensemble Mean, Initial Condition, Simulasi.
ABSTRACT
Products of numerical weather prediction (NWP) contain uncertainty value because there is error’s variation so that it has a tendency Equity skills with increasing projection A Time Forecast models, a numerical models would Depending on several parameters such as the initial conditions, so we need NWP model products projection on the reintialitation differences. Data Used in this research is FNL, the Observation data in format bufr and Observation of STAMET Nabire. In this study we use Ensemble Means Method to know how projection of the models did Simulation Heavy rain in Nabire. Ensemble mean’s value show the pattern of observation’s distribution compare to initializations value although there is still deviation in each parameters. Heavy rainfall simulation with ensemble mean from several initialization show similar phase with observation but has underestimate value. Output of model with assimilation need less time to spin up than without assimilation.
Key words : NWP, Ensemble Mean, Initial Condition, Simulation.

Behaviour of thin-walled beams with open section in presence of large torsion is investigated in this work. The equilibrium equations are derived in the case of elastic behaviour without any assumption on torsion angle amplitude. This model is extended to finite element formulation in the same circumstances where 3D beams with two nodes and seven degrees of freedom per node are considered. Due to large torsion assumption and flexural–torsional coupling, new matrices are obtained in both geometric and initial stress parts of the tangent stiffness matrix. Incremental-iterative Newton–Raphson method is adopted in the solution of the nonlinear equations. Many applications are presented concerning the nonlinear and post-buckling behaviour of beams under torsion and bending loads. The proposed beam element is efficient and accurate in predicting bifurcations and nonlinear behaviour of beams with asymmetric sections. It is proved
that the bifurcation points are in accordance with nonlinear stability solutions. The convenience of the model is outlined and the limit of models developed in linear stability is discussed.

ABSTRACT: The general topic investigated in this thesis is “structural health monitoring”, with special care being devoted to damage detection and localization. The study is focused on methods which work in the space of the observed variables, where the global information measures can be used to detect the damage. In this context damage detection is demanded to global measures such as entropy or Lyapunov exponents. The comparison of these measures computed in subspaces of the observed variables or in their expansions, allows one to perform a sort of sensitivity analysis on the role of the variables involved in the problem.
Such global measures are able to detect but not to directly  localize damage. For this purpose, a new approach to detect and localize the damage is formulated and implemented. It exploits response surface techniques to approximate the relationship among the observed variables. Comparing the resulting models in different damaged and undamaged situations identifies the response differences and their causes.
The response surface procedure is described from its basic theoretical aspects up to the features of its numerical implementation. Additionally, the global measures introduced above drive the analyst in establishing whether or not the problem is well posed, i.e., whether or not the set of measured quantities are able to detect the specific damage to be localized.
The validation of the proposed methodology is first numerically pursued by applying it to the benchmark case set up by the Structural Health Monitoring Panel of the American Society of Civil Engineering (ASCE). The procedure is then tested on two different experimental situations. While the first study of a three-dimensional steel frame reproduces the features of the benchmark problem, the second investigation covers a monumental structure situation, where damage is represented by more or less extended cracks in the masonry. The potential expressed by the procedure also in this second application seems to promise interesting exploitation possibilities.

We consider the Universe deep inside the cell of uniformity. At these scales, the Universe is filled with inhomogeneously distributed discrete structures (galaxies, groups and clusters of galaxies), which perturb the background Friedmann model. Here, the mechanical approach (Eingorn & Zhuk, 2012) is the most appropriate to describe the dynamics of the inhomogeneities which is defined, on the one hand, by gravitational potentials of inhomogeneities and, on the other hand, by the cosmological expansion of the Universe. In this paper, we present additional arguments in favor of this approach. First, we estimate the size of the cell of uniformity. With the help of the standard methods of statistical physics and for the galaxies of the type of the Milky Way and Andromeda, we get that it is of the order of 190 Mpc which is rather close to observations. Then, we show that the nonrelativistic approximation (with respect to the peculiar velocities) is valid for $z \lesssim 10$, i.e. approximately for 13 billion years from the present moment. We consider scalar perturbations and, within the $\Lambda$CDM model, justify the main equations. Moreover, we demonstrate that radiation can be naturally incorporated into our scheme. This emphasizes the viability of our approach. This approach gives a possibility to analyze different cosmological models and compare them with the observable Universe. For example, we indicate some problematic aspects of the spatially flat models. Such models require a rather specific distribution of the inhomogeneities to get a finite potential at any points outside gravitating masses. We also criticize the application of the Schwarzschild-de Sitter solution to the description of the motion of test bodies on the cosmological background.

— Electrical devices often use RC, LC or RLC circuit to design power amplifiers, filters and mixers etc. Complex iterative algorithms are used for the simulation of these circuits.. This paper illustrates numerical experiments on growth of rounding off error in simulation of simple RC circuit using fourth order Runge-Kutta method (RK) and the Runge-Kutta-Fehlberg with adaptive step size control method (RKF). Our analysis indicates that in simulations with RK method, round off error grows ~ 80% with 10-15 iterations and ~96-98% within 100 iterations with different step sizes and double precision. In the simulations with RKF method round off error grows to 70% with 10-20 iterations and ~80% within 100 iterations. It does not exceed 80% for 1000 of iterations for single and double precision. This indicates that growth of round off error in RKF method is less and it should be used to minimize round off error.

In this work, we modeled double- and triple-cluster 3D hydraulic fracturing in a single-layer, quasi-brittle shale formation using planar CZM and XFEM-based CZM including slit flow and poro-elasticity for fracture and matrix spaces, respectively, in Abaqus. Our fully-coupled pore pressure-stress Geo-mechanics model includes leak-off as a continuum-based fluid flow component coupled with the other unknowns in the problem. Having compared the triple-cluster fracturing results from planar CZM with those from XFEM-based CZM, we found that the stress shadowing effect of multiple hydraulic fractures on each other can cause these fractures to rationally propagate out of plane; this also demonstrates the advantages of the second method compared to the first one. We investigated the effect of this arbitrary propagation direction on not only the fractures’ length, aperture, and the required injection pressure, but also fractures’ connection to the wellbore. Depending on the spacing and the number of clusters per stage, this connection can be gradually disrupted with time due to the near-wellbore fracture closure which may embed proppant particles on the fracture wall, or screen out the fracture at early stimulation times. Comparing all studied cases, we concluded that the double-cluster, simultaneous fracturing with 100-ft spacing provides the most viable fracture set for long-term production.

Direct torque control (DTC) is known to produce quick and robust response in alternating current drives. However, during steady state, notable torque and flux ripple occur. They are reflected in speed estimation, speed response and also in increased noise. The electrically excited alternating current induction motor has typically small synchronous inductance values and quite low transient values because of the damper windings mounted on the rotor therefore the torque and stator flux linkage ripples are high in conventional direct torque control due to the implementation of hysteresis control. In this paper, an attempt is made to address this problem using direct torque control scheme with space vector pulse width modulation scheme. It is based on the compensation of the stator flux linkage vector error using the space vector modulation in order to decrease the torque and flux linkage ripples and produced fixed switching frequency under the principle that the torque is controlled by the torque angle on alternating current induction motor. The alternating current induction motor is supplied by a two level thyristor inverter powered by space vector modulation. Conventional principles of direct torque control and space vector pulse width modulation were described. It can be used in various applications like electric vehicles, and industrial control where field weakening operation is required. Simulation research is carried out in Matlab/Simulink which illustrates steady state and dynamic performances of the developed system. Simulation results demonstrate the validity and effectiveness of the torque control response which properly combines with space vector pulse width modulation that shows faster dynamic response, lower torque ripple and lower flux ripple. Moreover, simple Matlab/Simulink model is introduced for two level space vector modulation inverter which can be realized and implemented in practice for three phase alternating current induction.

Nowadays, transformers are made of conventional magnetic cores which are constructed of a single grainoriented or amorphous, magnetic steel. Even though, the transformer is the most efficient of electrical machines, with efficiencies typically above 90%, it is possible to improve transformer performance by using composite magnetic cores. Patents related to this simple and effective technique can be traced back to 1929. The specific technique can be applied to wound core distribution transformers. By using wound cores constructed with a combination of conventional and high permeability grain-oriented steel the total owing cost (TOC) of the transformer can be reduced effectively. This paper presents a brief review of patents on wound and composite magnetic cores and introduces a generalized technique for the determination of the optimum design variables of a new composite wound core design.