• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 153
  • 110
  • 25
  • 17
  • 12
  • 6
  • 6
  • 5
  • 4
  • 3
  • 3
  • 2
  • 2
  • 1
  • 1
  • Tagged with
  • 395
  • 395
  • 99
  • 86
  • 85
  • 63
  • 49
  • 48
  • 46
  • 43
  • 42
  • 41
  • 39
  • 36
  • 36
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

The Behavior of Moment Resisting Steel Frames Under Seismic Excitation with Variation of Geometric Dimensions of Architectural Setbacks

Kayikci, Duygu y 12 May 2011 (has links)
This study investigates seismic response of the Moment-Resisting-Steel Frames (MRSF) with the architectural setbacks. The main objective of the study is to understand the variation of the elastic and inelastic, static and dynamic behavior with changes in the geometric dimensions of the tower portion. A second objective of the study is to determine the adequacy of the analysis procedures of various rigors, specified in current seismic design provision, in predicting those behaviors for MRSF with various size of setback. The analytical study is conducted using a regular and 16 irregular models to capture all possible combinations of configuration of setback in five-story, five-bay MRSFs. An irregular model is developed by gradually changing the horizontal and vertical dimensions of the tower portion of the regular base 2D frame-model. All models were designed for (a) equal global displacement and uniform distribution of inter-story drift under First-Mode (FM) lateral force distribution pattern at first significant yield, and (b) equal period of vibration at the first mode, using Nonlinear Static Seismic analysis procedure. Among the conclusions derived from the research is that the variation of (a) the elastic and inelastic inter-story drift, the ductility demand for the top three stories, and (b) the elastic and inelastic global displacement exhibited a pattern similar to the variation of the FM participation factor at the roof, PF1Φr,1. The square-root-of-sum-of-square (SRSS) distribution provided accurate estimates of elastic story shear and inter-story drift demand as well as the story yield strength and drift.
62

Dynamic analysis of multiple-body floating platforms coupled with mooring lines and risers

Kim, Young-Bok 30 September 2004 (has links)
A computer program, WINPOST-MULT, is developed for the dynamic analysis of a multiple-body floating system coupled with mooring lines and risers in the presence of waves, winds and currents. The coupled dynamics program for a single platform is extended for analyzing multiple-body systems by including all the platforms, mooring lines and risers in a combined matrix equation in the time domain. Compared to the iteration method between multiple bodies, the combined matrix method can include the full hydrodynamic interactions among bodies. The floating platform is modeled as a rigid body with six degrees of freedom. The first- and second-order wave forces, added mass coefficients, and radiation damping coefficients are calculated from the hydrodynamics program WAMIT for multiple bodies. Then, the time series of wave forces are generated in the time domain based on the two-term Volterra model. The wind forces are separately generated from the input wind spectrum and wind force formula. The current is included in Morison's drag force formula. In case of FPSO, the wind and current forces are generated using the respective coefficients given in the OCIMF data sheet. A finite element method is derived for the long elastic element of an arbitrary shape and material. This newly developed computer program is first applied to the system of a turret-moored FPSO and a shuttle tanker in tandem mooring. The dynamics of the turret-moored FPSO in waves, winds and currents are verified against independent computation and OTRC experiment. Then, the simulations for the FPSO-shuttle system with a hawser connection are carried out and the results are compared with the simplified methods without considering or partially including hydrodynamic interactions.
63

Benchmarking Points-to Analysis

Gutzmann, Tobias January 2013 (has links)
Points-to analysis is a static program analysis that, simply put, computes which objects created at certain points of a given program might show up at which other points of the same program. In particular, it computes possible targets of a call and possible objects referenced by a field. Such information is essential input to many client applications in optimizing compilers and software engineering tools. Comparing experimental results with respect to accuracy and performance is required in order to distinguish the promising from the less promising approaches to points-to analysis. Unfortunately, comparing the accuracy of two different points-to analysis implementations is difficult, as there are many pitfalls in the details. In particular, there are no standardized means to perform such a comparison, i.e, no benchmark suite - a set of programs with well-defined rules of how to compare different points-to analysis results - exists. Therefore, different researchers use their own means to evaluate their approaches to points-to analysis. To complicate matters, even the same researchers do not stick to the same evaluation methods, which often makes it impossible to take two research publications and reliably tell which one describes the more accurate points-to analysis. In this thesis, we define a methodology on how to benchmark points-to analysis. We create a benchmark suite, compare three different points-to analysis implementations with each other based on this methodology, and explain differences in analysis accuracy. We also argue for the need of a Gold Standard, i.e., a set of benchmark programs with exact analysis results. Such a Gold Standard is often required to compare points-to analysis results, and it also allows to assess the exact accuracy of points-to analysis results. Since such a Gold Standard cannot be computed automatically, it needs to be created semi-automatically by the research community. We propose a process for creating a Gold Standard based on under-approximating it through optimistic (dynamic) analysis and over-approximating it through conservative (static) analysis. With the help of improved static and dynamic points-to analysis and expert knowledge about benchmark programs, we present a first attempt towards a Gold Standard. We also provide a Web-based benchmarking platform, through which researchers can compare their own experimental results with those of other researchers, and can contribute towards the creation of a Gold Standard.
64

Entropy, information theory and spatial input-output analysis

Batten, David F. January 1981 (has links)
Interindustry transactions recorded at a macro level are simply summations of commodity shipment decisions taken at a micro level. The resulting statistical problem is to obtain minimally biased estimates of commodity flow distributions at the disaggregated level, given various forms of aggregated information. This study demonstrates the application of the entropy-maximizing paradigm in its traditional form, together with recent adaptations emerging from information theory, to the area of spatial and non-spatial input-output analysis. A clear distinction between the behavioural and statistical aspects of entropy modelling is suggested. The discussion of non-spatial input-output analysis emphasizes the rectangular and dynamic extensions of Leontief's original model, and also outlines a scheme for simple aggregation, based on a criterion of minimum loss of information. In the chapters on spatial analysis, three complementary approaches to the estimation of interregional flows are proposed. Since the static formulations cannot provide an accurate picture of the gross interregional flows between any two sectors, Leontief's dynamic framework is adapted to the problem. The study concludes by describing a hierarchical system of models to analyse feasible paths of economic development over space and time. / digitalisering@umu
65

RUMBA: Runtime Monitoring and Behavioral Analysis Framework for Java Software Systems

Ashkan, Azin January 2007 (has links)
A goal of runtime monitoring is to observe software execution to determine whether it complies with its intended behavior. Monitoring allows one to analyze and recover from detected faults, providing prevention activities against catastrophic failure. Although runtime monitoring has been in use for so many years, there is renewed interest in its application largely because of the increasing complexity and ubiquitous nature of software systems. To address such a demand for runtime monitoring and behavioral analysis of software systems, we present RUMBA framework. It utilizes a synergy between static and dynamic analyses to evaluate whether a program behavior complies with specified properties during its execution. The framework is comprised of three steps, namely: i) Extracting Architecture where reverse engineering techniques are used to extract two meta-models of a Java system by utilizing UML-compliant and graph representations of the system model, ii) Seeding Objectives in which information required for filtering runtime events is obtained based on properties that are defined in OCL (Object Constraint Language) as specifications for the behavioral analysis, and iii) Runtime Monitoring and Analysis where behavior of the system is monitored according to the output of the previous stages, and then is analyzed based on the objective properties. The first and the second stages are static while the third one is dynamic. A prototype of our framework has been developed in Java programming language. We have performed a set of empirical studies on the proposed framework to assess the techniques introduced in this thesis. We have also evaluated the efficiency of the RUMBA framework in terms of processor and memory utilization for the case study applications.
66

防災担当者の技術力向上のための耐震設計の共通化と地震応答の統合的可視化

堀, 宗朗, HORI, Muneo, 井上, 純哉, INOUE, Junya, 市村, 強, ICHIMURA, Tsuyoshi, 中村, 光, NAKAMURA, Hikaru, 若井, 明彦, WAKAI, Akihiko, 海老澤, 健正, EBISAWA, Takemasa, 山口, 直也, YAMAGUCHI, Naoya 07 1900 (has links)
No description available.
67

RUMBA: Runtime Monitoring and Behavioral Analysis Framework for Java Software Systems

Ashkan, Azin January 2007 (has links)
A goal of runtime monitoring is to observe software execution to determine whether it complies with its intended behavior. Monitoring allows one to analyze and recover from detected faults, providing prevention activities against catastrophic failure. Although runtime monitoring has been in use for so many years, there is renewed interest in its application largely because of the increasing complexity and ubiquitous nature of software systems. To address such a demand for runtime monitoring and behavioral analysis of software systems, we present RUMBA framework. It utilizes a synergy between static and dynamic analyses to evaluate whether a program behavior complies with specified properties during its execution. The framework is comprised of three steps, namely: i) Extracting Architecture where reverse engineering techniques are used to extract two meta-models of a Java system by utilizing UML-compliant and graph representations of the system model, ii) Seeding Objectives in which information required for filtering runtime events is obtained based on properties that are defined in OCL (Object Constraint Language) as specifications for the behavioral analysis, and iii) Runtime Monitoring and Analysis where behavior of the system is monitored according to the output of the previous stages, and then is analyzed based on the objective properties. The first and the second stages are static while the third one is dynamic. A prototype of our framework has been developed in Java programming language. We have performed a set of empirical studies on the proposed framework to assess the techniques introduced in this thesis. We have also evaluated the efficiency of the RUMBA framework in terms of processor and memory utilization for the case study applications.
68

Component Mode Synthesis Method on the Dynamic Characteristics of Shrouded Turbo Blades

Chen, Hong-kai 21 July 2011 (has links)
The dynamic characteristics of shroud blade group played a significant role in steam turbine design. However, the complex shape and periodical structure of shroud blades make it so hard to find its dynamic characteristics under high speed operation. The complicate shape, periodic structure, and tedious computation limit the application of finite element method in the design analysis of shroud group blades. In order to design the shroud blade group, the component mode synthesis method was employed to derive the system dynamic equation of the grouped periodical blades. For simplicity, a pre-twisted and tapered cantilever beam is used to derive the approximate analytic solution of a rotating turbo blade. Then the approximated eigen solution of single blade is synthesized in company with the constrain condition by using the component mode synthesis method. In order to confirm the feasibility of the proposed simulation method, a real size turbine blade is used to discuss in the study. Through a comparison between the results solved from the proposed method and finite element method of single blade and shroud blade group to prove the reliability of the proposed method. The effect of blade parameters on the dynamic characteristic of shroud blade group has investigated in this work. Numerical results indicate the proposed method is feasible and effective in dynamic design analyses of the shroud blade group.
69

Loads on Tie-Down Systems for Floating Drilling Rigs during Hurricane Conditions

Bae, Yoon Hyeok 16 January 2010 (has links)
Tie-down systems are used to fasten drilling rigs to the deck of offshore structures during harsh environmental conditions such as hurricanes. During Hurricane Ivan (2004) and Katrina (2005), a number of offshore structures were moved and several tie-down systems were damaged. In the present study, the reaction force and connection capacity of tie-down systems for a TLP and SPAR are investigated. The environmental conditions are taken from the API Bulletin 2INT-MET which has been updated after several major storms during 2004-2005. The hydrodynamic coefficients of the TLP and SPAR are obtained using a 3D diffraction/radiation panel method. The motions of the TLP and SPAR are then simulated in the time domain by using the hull-mooring-riser coupled dynamic analysis tool CHARM3D. Based on the simulated motion and acceleration time series, the inertial and gravity loads on derrick and skid base footing are calculated. In addition to the inertial-gravity loads, wind forces exerted on the derrick are also calculated. All the external forces and resultant hull motions are simulated for 100-year, 200-year and 1000-year storms to observe the derrick structural integrity with increasing environmental intensity. Various environmental headings are also considered to find the maximum reaction forces. In the present method, the phase differences between gravity-inertia forces and wind forces are taken into consideration to obtain more realistic loads on derrick and skid base footings. This research shows that the maximum and minimum load values are appreciably higher for the SPAR. In addition, the direction of external forces is also important to determine maximum reaction forces on footings. The capacities of the clamps in slip, bolt tension, and bolt shear can be also analyzed using the resultant data to provide guidance on appropriate design values.
70

An Analysis Of Degirmendere Shore Landslide During 17 August 1999 Kocaeli Earthquake

Bulbul, Oguzhan 01 December 2006 (has links) (PDF)
In this study, the failure mechanism of the shore landslide which occured at Degirmendere coast region during 17 August 1999 Kocaeli (Izmit) - Turkey earthquake is analyzed. Geotechnical studies of the region are at hand, which reveal soil properties and geological formation of the region as well as the topography of the shore basin after deformations. The failure is analyzed as a landslide and permanent displacements are calculated by Newmark Method under 17 August 1999 Izmit record, scaled to a maximum acceleration of 0.4g. There are discussions on the main dominating mechanism of failure / landslide, liquefaction, fault rupture and lateral spreading. According to the studies, the failure mechanism is a seismically induced shore landslide also triggered by liquefaction and fault rupture, accompanied by the mechanism of lateral spreading by turbulence. A seismically induced landslide is discussed and modeled in this study. The finite element programs TELSTA and TELDYN are employed for static and dynamic analyses. Slope stability analyses are performed with the program SLOPE. The permanent displacements are calculated with Newmark Method, with the help of a MATLAB program, without considering the excess pore pressures.

Page generated in 0.0434 seconds