http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
DYNAMICS OF TENSION LEG PLATFORM TETHERS AT LOW TENSION. PART 2-COMBINED EXCITATION
PATEL,M.H.,PARK,H.I. 韓國海洋大學校 附設 海洋科學技術硏究所 1993 硏究論文集 Vol.2 No.1
In conventional design practice, tension leg platform (TLPs) tethers are designed to be highly tensioned. This high pre-tension is, however, a significant restriction to the payload growth of TLPs. This paper reports on the second stage of an investigation into the vibrations of tethers at low tension. Unlike conventional approaches for slender marine structures, tethers are considered to be simultaneously subjected to time-varying axial forces (parametric excitation)and lateral forces (forcing excitation). Therefore, the tethers can be regarded as dynamic systems under combined excitation. In order to solve this combined excitation problem, the governing partial differential equation of lateral motion of a tether is reduced to a nonlinear differential equation. This nonlinear equation of combined excitation is solved by using both Romberg's method and the fourth-order Runge-Kutta method together. It is found that taking account of combined excitation is of little importance compared to forcing excitation in the first instability region of the Mathieu stability chart. However, from the second instability regions onwards, that is, when the natural periods of tethers are equal or shorter than excitation periods, combined excitation becomes significant. Therefore, since the dynamic operating conditions of most tethers correspond to higher-order instability regions, it is necessary to consider combined excitation in the dynamic analysis of tethers. The results of theoretical developments on combined excitation are applied to example tethers and used to show that from the third instability regions onwards, tether lateral response amplitudes increase with pre-tension reduction, in the second instability region, the amplitudes do not change, whereas, in the first instability region, the response amplitudes rather decrease with pre-tension reduction.
Prediction of strength of reinforced lightweight soil using an artificial neural network
Park, H.I.,Kim, Y.T. Emerald Group Publishing Limited 2011 Engineering computations Vol.28 No.5
<B>Purpose</B> - Reinforced lightweight soil (RLS) consisting of dredged soil, cement, air-foam, and waste fishing net is considered to be an eco-friendly backfilling material because it provides a means to recycle both dredged soil and waste fishing net. It may be difficult to find an optimum mixing ratio of RLS considering the design criteria and the construction's situation using the limited test results because the unconfined compressive strength is complicatedly influenced by various mixing ratios of admixtures. As a result, in order to expedite the field application of RLS, an appropriate prediction method is needed. The paper aims to address these issues. <B>Design/methodology/approach</B> - In this study, an artificial neural network (ANN) model that was based on experimental test results performed on various mixing ratios, was developed to predict the unconfined compressive strength of RLS. <B>Findings</B> - It was found that the unconfined compressive strength of RLS at a given mixing ratio could be reasonably estimated using the developed neural network model. In addition, sensitivity analysis was also conducted to evaluate the effect of mixing conditions on the compressive strength of RLS. <B>Practical implications</B> - RLS is considered to be environmentally friendly because it provides a means to recycle both dredged soil and waste fishing net. The contractors could use the proposed ANN model as an alternative method to predict the strength of RLS with a specific mixing ratio. <B>Originality/value</B> - This paper reveals that the developed ANN model can be served as a simple and reliable predictive tool for the strength of RLS without excessive laboratory tests for various admixture contents. An optimum admixture ratio of composed materials to get a designed strength could be easily found by using the proposed ANN model.
Combined axial and lateral responses of tensioned buoyant platform tethers
Patel,M. H,Park,H. I 韓國海洋大學校 附設 海洋科學技術硏究所 1997 硏究論文集 Vol.5 No.-
This paper presents the results of an investigation into the combined axial and lateral vibrations of the tethers of tensioned buoyant platforms, (TBPs). Wave-induced motions of the TBP excite tether vibrations through lateral forces at the tether top end (called external or forcing excitation in this paper) combined with a time varying axial force (called parametric excitations here). Although the forcing and parametric excitations have been considered separately in the research literature, this paper examines their combined effects-particularly with a view to determining tether behaviour for different water depths. The governing partial differential equation of tether lateral motion is reduced to a nonlinear differential equation and solved by a combination of the Romberg method and the fourth-order Runge-Kutta method. Comparisons for tether vibrations when taking both axial and lateral forcing into account and when considering axial and lateral forcing separately are presented. It is shown that the combined excitation gives greater amplitude of vibration with this feature being particularly dominant in even numbers of the instability region of the Mathieu stability chart. The frequency of oscillation of the combined response is also dependent on the relative magnitudes of axial and lateral excitations. The results demonstrate that the above is true for a wide range of water depths.
Shilpa PARKHI(Shilpa PARKHI ),Venkata Mrudula BHIMAVARAPU(Venkata Mrudula BHIMAVARAPU ),Kiran KARANDE(Kiran KARANDE ),Shailesh RASTOGI(Shailesh RASTOGI ),Aashi RAWAL(Aashi RAWAL ) 한국유통과학회 2022 The Journal of Asian Finance, Economics and Busine Vol.9 No.9
The primary objective of the current study is to ascertain the effect of transparency and disclosure (T&D) on the value of banks operating in the Indian banking sector. It also includes finding the moderating impact of financial distress (FD) and environmental, social, and governance (ESG) on the association between T&D and the valuation of banks. The study employs Panel data analysis (PDA) to analyze data and produce novel results thereafter. The authors of the study have considered using data of secondary nature which is sourced from banks operating in the Indian banking industry. Data in the current study has been considered for ten financial years, i.e., 2010 to 2019. The results reveal that T&D positively impacts a firm’s valuation. We have also found evidence that financial distress and ESG (Environmental, Social, and Governance) significantly impact the value of firms under the influence of T&D. As far as we are aware, no study of this kind has been done yet in any developing nation to determine the effect that T&D, FD, and ESG have on the value of Indian banks. This paper can help future researchers in their respective studies that will involve the study variables (FD, T&D, and ESG).
Rebuilding Operational Risk Management Capabilities: Lessons Learned from COVID-19
JADWANI, Barkha,PARKHI, Shilpa,KARANDE, Kiran,BARGE, Prashant,BHIMAVARAPU, Venkata Mrudula,RASTOGI, Shailesh Korea Distribution Science Association 2022 The Journal of Asian Finance, Economics and Busine Vol.9 No.9
Globally, COVID-19 has significantly impacted many different organizations and people. From the banks' perspective, this pandemic has affected banks' corporate and retail customers. Also, banks had to adjust to distributed workforce model. This paper analyses the lessons learned from the COVID-19 pandemic, which can be effectively used to rebuild banks' Operational Risk Management capabilities. The present study used the survey research methodology, which includes structured questionnaires completed by senior banking professionals to analyze the learnings from COVID-19 and understand the distributed workforce model and remote working effectiveness. Findings: The Pandemic accelerated the pace of digital transformation. The lockdown imposed due to the pandemic led to employees working remotely, which has been effective because of enhanced digital capabilities. However, enhanced monitoring is required to prevent data-related issues, and action needs to be taken to address challenges faced in having a remote distributed workforce model, like negative impact on on-the-job learning, data-related risks, and employee wellbeing. COVID-19 is an unprecedented event that could not have been predicted in any scenario analysis. This crisis has highlighted various systemic drawbacks that need to be addressed. Banks can apply the lesson learned from this Pandemic to become more robust in the future.
Robust Control for Seeker Scan Loop using Sliding Modes
Dharmveer,Shailaja Kurode,Prasad Parkhi,Bhagyashri Tamhane 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10
This paper presents robust control of seeker system used in missile target scanning and tracking. The mathematical model for seeker system is considered. A sliding mode controller (SMC) is designed to compensate uncertain coupling effect and external disturbances during scan phase. The model of the plant is based on first-principle method. The dynamic equations of motion are formulated with the assumption that the seeker system is a rigid body with no mass imbalance. These equations of motion are considered in cascade with DC motor equations which provides the actuating torque to the gimbal axes of the seeker system. The performance of the controller is validated in simulations.
Simultaneous State and Disturbance Estimation for Seeker System using Sliding Modes
Bhagyashri Tamhane,Shailaja Kurode,Prasad Parkhi,Dharmveer 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10
In this paper simultaneous estimation of states and disturbance for seeker system of a missile using sliding mode observer (SMO) has been proposed. The modeling of the plant is done by classical method and the complete seeker system has been simulated for generation of spiral scan loop with control input provided by a simple state feedback controller. An extended state observer using sliding modes is designed to estimate the system states and the total lumped disturbances acting on the system. The estimated disturbance takes into account the disturbance due to cross coupling in the gimbal system and externally added sinusoidal disturbance in input channel. Simulations verify that the output estimation error is made zero in finite time due to sliding modes and the estimated disturbance is in close agreement with actual disturbance.