Dynamic Analysis of a Jack-Up Rig, SDOF Approach: Design Consideration — I

2013 ◽  
Author(s):  
Francisco J. Godoy ◽  
Fernando Lorenzo
Keyword(s):  
Dynamic Analysis ◽  
Static Analysis ◽  
Dynamic Effect ◽  
Wave Loads ◽  
Inertial Load ◽  
Base Shear ◽  
Oil Drilling ◽  
Analogy Method ◽  
Specific Assessment ◽  
Jack Up

A jack up rig, such as those used for oil drilling in the Gulf of Mexico, is a dynamic sensitive system subjected to random and periodic environmental loads (wave, wind, current, etc.), in which the inertia forces cannot be ignored. However, a static load analysis approach can be justified only if an extra inertial load set, due to the dynamic effect response, is included in the analysis. The Society of Naval Architects and Marine Engineers, SNAME T&R 5-5A, “Guidelines for Site Specific Assessment of Mobile Jack-Up Units”[1], addresses the calculation of the inertial load set by using the classical Single Degree of Freedom (SDOF) analogy to calculate such dynamic effect. This study evaluates how far apart crucial structural members’ stresses/loads obtained by using the SDOF analogy method are from those values obtained from a more realistic modal dynamic analysis. The analysis is performed for wave loads at different heights and frequencies such as those existing on extreme or severe design conditions as a storm. Although a jack up rig structure presents some non-linearities, especially in the legs-hull contact areas and the spud-cans interaction with the soil; a modal superposition analysis can be used if proper linearization is considered. The results of this study for a jack show that the SDOF analogy method tends to underestimate the base shear loads for high wave periods and conversely overestimate some stresses on crucial members, such as the legs’ chords close to the hull for all the wave periods. This study shows that the stresses on one of the legs’ chord of the most loaded leg, due to the dynamic effect produced by the harmonic loads calculated with the SDOF analogy developed in this study tend to be overestimated as the wave period decreases. Conversely, the calculation of the base shear of the structure employing a quasi-static analysis with inertial load set (ILS) as calculated in this study shows that the base shear forces difference between the modal dynamic analysis and the quasi static analysis tends to decrease as the periods of the wave decreases.

Dynamic Analysis and Evaluation of Wind Turbine Towers

2012 ◽  
Vol 193-194 ◽  
pp. 639-642 ◽  
Author(s):  
Chang Zheng Chen ◽  
Ping Ping Pan ◽  
Shi Wei Zhang ◽  
Meng Qiang
Keyword(s):  
Dynamic Analysis ◽  
Wind Turbine ◽  
Static Analysis ◽  
Dynamic Effect ◽  
Coupling Theory ◽  
Analysis And Evaluation ◽  
Static And Dynamic Analysis ◽  
Wind Turbine Towers ◽  
Fluid Coupling ◽  
The Impact

This paper presents static and dynamic analysis of wind turbine towers which is supporting a 1.5MW wind turbine based on the theory of FEM. In static analysis, the modal frequencies of the towers are analyzed without wind load. In dynamic analysis, by the fluid-coupling theory, the dynamic effect of wind loads on the towers is calculated. It can be concluded that the main errors under the different load situations is caused by the impact of fluid structure coupling.

scholarly journals Analisis Statik Beban Gempa Pada Perencanaan Struktur Gedung Rektorat UNHASY Tebuireng Jombang

2020 ◽  
Vol 14 (3) ◽  
pp. 211-217
Author(s):  
Titin Sundari ◽  
◽  
Abdiyah Amudi ◽  
Totok Yulianto ◽  
Rahma Ramadhani ◽  
...  
Keyword(s):  
Dynamic Analysis ◽  
Static Analysis ◽  
Shear Force ◽  
Base Shear ◽  
Lateral Forces ◽  
Drift Ratio

Static analysis is a simplification of dynamic analysis. Earthquake vibrations cause lateral forces at the base of the structure, and will be distributed on each floor of the building as lateral level forces. This analysis is suitable for regular building shapes. In accordance with SNI 1726: 2012, the value of the base shear force V is 103,039 kg for the X and Y directions. The displacement value is 54 mm and drift ratio ∆ < ∆a (allowable)

scholarly journals Analysis about Planning and Modification of the Upper and Lower Structures of the 38 Floor Apartment SkyHouse Project with Equivalent Static Analysis

Neutron ◽  
2022 ◽  
Vol 21 (2) ◽  
pp. 80-96
Author(s):  
Agus Fernando ◽  
Syahwandi ◽  
Resi Aseanto ◽  
Agung Sumarno
Keyword(s):  
Dynamic Analysis ◽  
Static Analysis ◽  
Structural Model ◽  
Structural Models ◽  
Actual Situation ◽  
Base Shear ◽  
Accurate Analysis ◽  
Analysis Process ◽  
Earthquake Force ◽  
The Difference

Abstract The modeled building structure is a regular building, with the number of levels being varied. The structural model is divided into 38-level portals. This research uses the help of the SAP2000 v21 program to facilitate the earthquake analysis process. The results of the study that will be compared are displacements between levels and base shear that occur due to earthquake forces. The results of the analysis have shown that static analysis produces greater results for the structural models compared to dynamic analysis. The difference in displacement between levels produced by the two methods in the three structural models is still included in the displacement limits between levels of permission required in SNI 1726-2012, so that the three models can still be analyzed by static analysis and dynamic analysis. Because the results of displacement and base shear in static analysis are greater than dynamic analysis, static analysis is safer if used for earthquake force loading in general structural calculations. Although in earthquake analysis, dynamic analysis is a more accurate analysis because the analysis process is closer to the actual situation.

scholarly journals Experimental study on dynamic effect of freestanding tower of sea-crossing bridge under wave load

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Zhou Daocheng ◽  
Zhang Bo ◽  
Xue Sisi ◽  
Wei Chengxun ◽  
Ou Jinping
Keyword(s):  
Experimental Study ◽  
Dynamic Effect ◽  
Pile Group ◽  
Test Model ◽  
Wave Loads ◽  
Test Results ◽  
Base Shear ◽  
Wave Load ◽  
Vibration Period ◽  
Bridge Tower

AbstractThere is a debate over whether the sea-crossing bridges undergo dynamic motions when exposed to wave loads. In order to verify the dynamic effect of the tower of sea-crossing bridge under wave load, an experimental study on dynamic effect of a freestanding tower of sea-crossing bridge is accomplished in this paper. Firstly, a test model for a typical bridge tower of pile group foundation under wave load is established by using a scale of 1:100. Secondly, a typical sea condition is designed for the response test of the bridge tower under wave load. The test results indicated that obvious vibration of top the tower occurs when the wave load period is close to the natural vibration period of the structure, and both displacement and base shear are amplified. The results in this paper will provide an important reference for whether the dynamic effect of wave load should be considered in the designs of bridge structure under wave load.

scholarly journals Hypervisor-assisted dynamic malware analysis

Cybersecurity ◽  
2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Roee S. Leon ◽  
Michael Kiperberg ◽  
Anat Anatey Leon Zabag ◽  
Nezer Jacob Zaidenberg
Keyword(s):  
Dynamic Analysis ◽  
Static Analysis ◽  
Cyber Security ◽  
Malware Analysis ◽  
Analysis Tools ◽  
Significant Performance

AbstractMalware analysis is a task of utmost importance in cyber-security. Two approaches exist for malware analysis: static and dynamic. Modern malware uses an abundance of techniques to evade both dynamic and static analysis tools. Current dynamic analysis solutions either make modifications to the running malware or use a higher privilege component that does the actual analysis. The former can be easily detected by sophisticated malware while the latter often induces a significant performance overhead. We propose a method that performs malware analysis within the context of the OS itself. Furthermore, the analysis component is camouflaged by a hypervisor, which makes it completely transparent to the running OS and its applications. The evaluation of the system’s efficiency suggests that the induced performance overhead is negligible.

scholarly journals Investigation of Data Dependencies by Dynamic Analysis of Sapfor

2020 ◽  
Vol 23 (3) ◽  
pp. 473-493
Author(s):  
Nikita Andreevich Kataev ◽  
Alexander Andreevich Smirnov ◽  
Andrey Dmitrievich Zhukov
Keyword(s):  
Dynamic Analysis ◽  
Programming Languages ◽  
Static Analysis ◽  
Automatic Parallelization ◽  
Parallel Execution ◽  
Control Flow ◽  
Analysis Tool ◽  
Data Dependencies ◽  
Program Parallelization ◽  
Memory Accesses

The use of pointers and indirect memory accesses in the program, as well as the complex control flow are some of the main weaknesses of the static analysis of programs. The program properties investigated by this analysis are too conservative to accurately describe program behavior and hence they prevent parallel execution of the program. The application of dynamic analysis allows us to expand the capabilities of semi-automatic parallelization. In the SAPFOR system (System FOR Automated Parallelization), a dynamic analysis tool has been implemented, based on on the instrumentation of the LLVM representation of an analyzed program, which allows the system to explore programs in both C and Fortran programming languages. The capabilities of the static analysis implemented in SAPFOR are used to reduce the overhead program execution, while maintaining the completeness of the analysis. The use of static analysis allows to reduce the number of analyzed memory accesses and to ignore scalar variables, which can be explored in a static way. The developed tool was tested on performance tests from the NAS Parallel Benchmarks package for C and Fortran languages. The implementation of dynamic analysis, in addition to traditional types of data dependencies (flow, anit, output), allows us to determine privitizable variables and a possibility of pipeline execution of loops. Together with the capabilities of DVM and OpenMP these greatly facilitates program parallelization and simplify insertion of the appropriate compiler directives.

scholarly journals Hybrid-Based Analysis Impact on Ransomware Detection for Android Systems

2021 ◽  
Vol 11 (22) ◽  
pp. 10976
Author(s):  
Rana Almohaini ◽  
Iman Almomani ◽  
Aala AlKhayer
Keyword(s):  
Dynamic Analysis ◽  
Static Analysis ◽  
Hybrid System ◽  
State Of The Art ◽  
Detection System ◽  
Detection Accuracy ◽  
Accuracy Rate ◽  
Hybrid Detection ◽  
Dynamic Analyses ◽  
Data Files

Android ransomware is one of the most threatening attacks that is increasing at an alarming rate. Ransomware attacks usually target Android users by either locking their devices or encrypting their data files and then requesting them to pay money to unlock the devices or recover the files back. Existing solutions for detecting ransomware mainly use static analysis. However, limited approaches apply dynamic analysis specifically for ransomware detection. Furthermore, the performance of these approaches is either poor or often fails in the presence of code obfuscation techniques or benign applications that use cryptography methods for their APIs usage. Additionally, most of them are unable to detect ransomware attacks at early stages. Therefore, this paper proposes a hybrid detection system that effectively utilizes both static and dynamic analyses to detect ransomware with high accuracy. For the static analysis, the proposed hybrid system considered more than 70 state-of-the-art antivirus engines. For the dynamic analysis, this research explored the existing dynamic tools and conducted an in-depth comparative study to find the proper tool to integrate it in detecting ransomware whenever needed. To evaluate the performance of the proposed hybrid system, we analyzed statically and dynamically over one hundred ransomware samples. These samples originated from 10 different ransomware families. The experiments’ results revealed that static analysis achieved almost half of the detection accuracy—ranging around 40–55%, compared to the dynamic analysis, which reached a 100% accuracy rate. Moreover, this research reports some of the high API classes, methods, and permissions used in these ransomware apps. Finally, some case studies are highlighted, including failed running apps and crypto-ransomware patterns.

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