Survival Probability Determination of Nonlinear Oscillators Subject to Evolutionary Stochastic Excitation

2014 ◽  
Vol 81 (5) ◽  
Author(s):  
Pol D. Spanos ◽  
Ioannis A. Kougioumtzoglou
Keyword(s):  
Survival Probability ◽  
Computational Cost ◽  
Stochastic Averaging ◽  
Nonlinear Ordinary Differential Equation ◽  
Stochastic Excitation ◽  
Analytical Technique ◽  
Stochastic Excitations ◽  
Response Variance ◽  
Time Varying Frequency

A novel approximate analytical technique for determining the survival probability and first-passage probability density function (PDF) of nonlinear/hysteretic oscillators subject to evolutionary stochastic excitation is developed. Specifically, relying on a stochastic averaging/linearization treatment of the problem, approximate closed form expressions are derived for the oscillator nonstationary marginal, transition, and joint-response amplitude PDFs and, ultimately, for the time-dependent oscillator survival probability. The developed technique exhibits considerable versatility, as it can handle readily cases of oscillators exhibiting complex hysteretic behaviors as well as cases of evolutionary stochastic excitations with time-varying frequency contents. Further, it exhibits notable simplicity since, in essence, it requires only the solution of a first-order nonlinear ordinary differential equation (ODE) for the oscillator nonstationary response variance. Thus, the computational cost involved is kept at a minimum level. The classical hardening Duffing and the versatile Preisach (hysteretic) oscillators are considered in a numerical examples section, in which comparisons with pertinent Monte Carlo simulations data demonstrate the reliability of the proposed technique.

Galerkin Scheme-Based Determination of Survival Probability of Oscillators With Fractional Derivative Elements

2016 ◽  
Vol 83 (12) ◽  
Author(s):  
Pol D. Spanos ◽  
Alberto Di Matteo ◽  
Yezeng Cheng ◽  
Antonina Pirrotta ◽  
Jie Li
Keyword(s):  
Fractional Derivative ◽  
Survival Probability ◽  
Stochastic Averaging ◽  
Kolmogorov Equation ◽  
System Response ◽  
Statistical Linearization ◽  
Van Der Pol ◽  
Galerkin Scheme ◽  
Confluent Hypergeometric Functions

In this paper, an approximate semi-analytical approach is developed for determining the first-passage probability of randomly excited linear and lightly nonlinear oscillators endowed with fractional derivative elements. The amplitude of the system response is modeled as one-dimensional Markovian process by employing a combination of the stochastic averaging and the statistical linearization techniques. This leads to a backward Kolmogorov equation which governs the evolution of the survival probability of the oscillator. Next, an approximate solution of this equation is sought by resorting to a Galerkin scheme. Specifically, a convenient set of confluent hypergeometric functions, related to the corresponding linear oscillator with integer-order derivatives, is used as orthogonal basis for this scheme. Applications to the standard viscous linear and to nonlinear (Van der Pol and Duffing) oscillators are presented. Comparisons with pertinent Monte Carlo simulations demonstrate the reliability of the proposed approximate analytical solution.

Advances in the Chromatographic Separation and Determination of Bioactive Compounds for Assessing the Nutrient Profile of Nuts

2020 ◽  
Vol 16 ◽  
Author(s):  
Natasa P. Kalogiouri ◽  
Natalia Manousi ◽  
Erwin Rosenberg ◽  
George A. Zachariadis ◽  
Victoria F. Samanidou
Keyword(s):  
Fatty Acids ◽  
Phenolic Compounds ◽  
Bioactive Compounds ◽  
High Performance ◽  
Unsaturated Fatty Acids ◽  
Nutritional Deficiencies ◽  
Analytical Technique ◽  
High Volatility ◽  
Analytical Approaches

Background:: Nuts have been incorporated into guidelines for healthy eating since they contain considerable amounts of antioxidants and their effects are related to health benefits since they contribute to the prevention of nutritional deficiencies. The micronutrient characterization is based mainly on the determination of phenolics which is the most abundant class of bioactive compounds in nuts. Terpenes constitute another class of bioactive compounds that are present in nuts and show high volatility. The analysis of phenolic compounds and terpenes are very demanding tasks that require optimization of the chromatographic conditions to improve the separation of the components. Moreover, nuts are rich in unsaturated fatty acids and they are therefore considered as cardioprotective. Gas chromatography is the predominant instrumental analytical technique for the determination of derivatized fatty acids and terpenes in food matrices, while high performance liquid chromatography is currently the most popular technique for the determination of phenolic compounds Objective:: This review summarizes all the recent advances in the optimization of the chromatographic conditions for the determination of phenolic compounds, fatty acids and terpenes in nuts Conclusion:: The state-of-the art in the technology available is critically discussed, exploring new analytical approaches to reduce the time of analysis and improve the performance of the chromatographic systems in terms of precision, reproducibility, limits of detection and quantification and overall quality of the results

scholarly journals The Past, Present and Future of Flow Cytometry in Central Nervous System Malignancies

2021 ◽  
Vol 4 (1) ◽  
pp. 11
Author(s):  
Evrysthenis Vartholomatos ◽  
George Vartholomatos ◽  
George A. Alexiou ◽  
Georgios S. Markopoulos
Keyword(s):  
Central Nervous System ◽  
Flow Cytometry ◽  
Nervous System ◽  
Therapeutic Agents ◽  
Phenotypic Characterization ◽  
Cell Phenotype ◽  
Analytical Technique ◽  
The Past ◽  
Current Review

Central nervous system malignancies (CNSMs) are categorized among the most aggressive and deadly types of cancer. The low median survival in patients with CNSMs is partly explained by the objective difficulties of brain surgeries as well as by the acquired chemoresistance of CNSM cells. Flow Cytometry is an analytical technique with the ability to quantify cell phenotype and to categorize cell populations on the basis of their characteristics. In the current review, we summarize the Flow Cytometry methodologies that have been used to study different phenotypic aspects of CNSMs. These include DNA content analysis for the determination of malignancy status and phenotypic characterization, as well as the methodologies used during the development of novel therapeutic agents. We conclude with the historical and current utility of Flow Cytometry in the field, and we propose how we can exploit current and possible future methodologies in the battle against this dreadful type of malignancy.

scholarly journals ANALISIS PERBEDAAN ABNORMAL RETURN DAN TRADING VOLUME ACTIVITY SEBELUM DAN SESUDAH PERISTIWA PENETAPAN UNDANG-UNDANG TAX AMNESTY

2021 ◽  
Vol 10 (3) ◽  
pp. 186-198
Author(s):  
I Komang Wisnu Wardhana ◽  
Hermanto Hermanto ◽  
I Nyoman Nugraha AP
Keyword(s):  
Abnormal Return ◽  
Trading Volume ◽  
Secondary Data ◽  
Volume Activity ◽  
Analytical Technique ◽  
Tax Amnesty ◽  
Average Abnormal Return ◽  
Before And After ◽  
The Difference

The purpose of this study was to determine the difference in the average abnormal return and trading volume activity before and after the enactment of the tax amnesty law on the LQ-45 index. The type of data used in this study is secondary data with data collection techniques using the documentation method. Determination of the sample in this study using purposive sampling method with certain criteria so as to obtain 45 samples. The analytical technique used in this research is paired sample t-test with an observation period of 10 days. The results of this study indicate that: (1) There is no difference in the average abnormal return before and after the enactment of the tax amnesty law. (2) There is no difference in the average trading volume activity before and after the enactment of the tax amnesty law. 

Inexpensive simple extraction of trace PAHs from water using PS-DVB monolithic beads

2018 ◽  
Vol 10 (39) ◽  
pp. 4813-4820 ◽  
Author(s):  
Visakha Chunhakorn ◽  
Phitchayapa Ratchathamma ◽  
Harry J. Whitlow ◽  
Orapin Chienthavorn
Keyword(s):  
Gas Chromatography ◽  
Polycyclic Aromatic Hydrocarbons ◽  
Aromatic Hydrocarbons ◽  
Analytical Technique ◽  
Divinyl Benzene ◽  
Polycyclic Aromatic ◽  
Simple Extraction ◽  
Sensitive Analytical Technique

A new simple and sensitive analytical technique based on polystyrene-divinyl benzene (PS-DVB) monolithic bead extraction followed by gas chromatography-mass spectroscopic detection (GC-MS) was developed for the determination of polycyclic aromatic hydrocarbons (PAHs) in water.

Sign in / Sign up

Export Citation Format

Share Document