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optimum parameters and performance of negative stiffness and inerter based dampers for base-isolated structures

BULLETIN OF EARTHQUAKE ENGINEERING 2023年第3期21卷 1411-1438页

作者： Ul Islam, Naqeeb Jangid, R. S. Indian Inst Technol Dept Civil Engn Mumbai 400076 Maharashtra India

Novel combinations of true negative stiffness dampers (NSDs) and inerter devices are used concurrently as supplemental dampers for response control of base-isolated structures. The combination of the inerter and NSD is denoted as negative stiffness inerter damper (NSID). Classical H infinity optimisation based on a well-known fixed-point theory of tuned mass dampers is used to derive optimal parameters for NSD and three configurations of NSIDs. Optimal NSIDs and NSD are supplemented to the base-isolated structure as passive control devices. The closed-form expressions for optimal parameters are derived, which will be useful for the initial design process of these devices for isolated structures. A numerical searching technique is used to verify the derived closed-form expressions for the optimal parameters of NSIDs. A comparative analysis is also run by utilising three configurations of NSIDs and a true NSD as supplemental control devices to the flexible base-isolated structure. The governing equations of motion are written in state-space form, and the performance of the proposed supplemental dampers for the base-isolated structure is investigated under real earthquake records. Time history analysis shows that the optimal NSIDs and NSD effectively control the objective variables of base displacement, inter-storey drift, and top storey acceleration. Especially under near-fault, which may bring isolation systems to critical working conditions, the proposed supplemental dampers cushion against failure by improving energy dissipation capacity compared to conventional passive dampers. Optimal NSID parameters are lower in magnitude than NSD parameters, resulting in a smaller damper size, which is desirable from a practical design standpoint.

关键词： Base isolation H infinity optimisation Near fault motion Negative stiffness dampers Negative stiffness inerter damper Numerical search technique optimum parameters

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optimum parameters and performance of tuned mass damper-inerter for base-isolated structures

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SMART STRUCTURES AND SYSTEMS 2022年第4期29卷 549-560页

作者： Jangid, Radhey Shyam Indian Inst Technol Dept Civil Engn Mumbai 400076 Maharashtra India

The optimum damping and tuning frequency ratio of the tuned mass damper-inerter (TMDI) for the base-isolated structure is obtained using the numerical searching technique under stationary white-noise and filtered white-noise earthquake excitation. The minimization of the isolated structure's mean-square relative displacement and absolute acceleration, as well as the maximization of the energy dissipation index, were chosen as the criteria for optimality. Using a curve-fitting technique, explicit formulae for TMDI damping and tuning frequency for white-noise excitation are then derived. The proposed empirical expressions for TMDI parameters are found to have a negligible error, making them useful for the effective design of base-isolated structures. The effectiveness of TMDI and its optimum parameters are influenced by the soil condition and isolation frequency, according to the comparison made of the optimized parameters and response with different soil profiles. The effectiveness of an optimally designed TMDI in controlling the displacement and acceleration response of the flexible isolated structure under real and pulse-type earthquakes is also observed and found to be increased as the inertance mass ratio increases.

关键词： cycloidal pulses filtered white-noise floor accelerations optimum parameters seismic base isolation stationary excitation tuned mass damper-inerter

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optimum parameters of tuned mass damper-inerter for damped structure under seismic excitation

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INTERNATIONAL JOURNAL OF DYNAMICS AND CONTROL 2022年第5期10卷 1322-1336页

作者： Prakash, Shiv Jangid, R. S. Indian Inst Technol Dept Civil Engn Mumbai 400076 India

The optimum tuning frequency ratio and damping of the tuned mass damper inerter (TMDI) used in damped single-degree-of-freedom (SDOF) structure subjected to stationary white-noise earthquake excitation is obtained with the help of numerical searching technique. Minimization of the mean-square absolute acceleration and relative displacement of the SDOF structure, as well as maximization of the energy dissipation index, are chosen as the criteria for optimal design. A curve-fitting method is used then to derive closed-form expressions for TMDI damping, tuning frequency, and optimized response which can easily be used for practical applications. The deviation of the optimal values obtained using proposed closed-form expressions is found to be negligible and therefore these expressions are convenient for the optimal effective design of TMDI for various structures. The usefulness of the proposed expressions of the TMDI parameters is then applied to multi-degree-of-freedom (MDOF) framed structures and a comparative study of the seismic response with and without TMDI (tuned for optimization of various objective functions) is done under real earthquake ground excitations. It is seen that an optimally designed TMDI is able to reduce the acceleration and displacement response of the MDOF structures.

关键词： Tuned mass damper inerter Stationary excitation optimum parameters Closed-form expression Seismic excitation Floor accelerations Floor displacement

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optimum parameters for production of ethanol from synthetic molasses by Saccharomyces cerevisiae 2

Optimum parameters for production of ethanol from synthetic ...

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2nd International Conference on Manufacturing Material Science and Engineering (ICMMSE)

作者： Reddy, P. Krishna Vijay, M. Kusuma, M. Ramesh, K. V. Govt Inst Chem Engn Visakhapatnam 530007 Andhra Pradesh India Centurion Univ Technol & Management Odisha Jatni India Andhra Univ Dept Chem Engn Visakhapatnam 530003 Andhra Pradesh India

Synthetic molasses is subjected to fermentation in the presence of Saccharomyces cerevisiae (yeast). The effects of pH, temperature, sugar concentration of solution, and yeast concentration are studied. The pH is varied from 1 to 8. The temperature is changed from 25 to 45celcius. Sugar concentration of solution is taken from 50 to 400 g per liter. Addition of yeast is in the range of 1 to 8 g per liter. From this study the optimum pH is found to be 4. The optimum initial solution temperature is 35celcius. optimum values of sugar concentration and yeast concentration are 300 and 2 g per liter respectively. (c) 2021 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the 2nd International Conference on Manufacturing Material Science and Engineering.

关键词： Ethanol Fermentation Molasses Yeast optimum parameters

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optimum parameters for production of ethanol from synthetic molasses by Saccharomyces cerevisiae

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Materials Today: Proceedings 2021年 46卷 154-156页

作者： P. Krishna Reddy M. Vijay M. Kusuma K.V. Ramesh Government Institute of Chemical Engineering Visakhapatnam 530007 India Centurion University of Technology and Management Odisha India Department of Chemical Engineering Andhra University Visakhapatnam 530003 India

Synthetic molasses is subjected to fermentation in the presence of Saccharomyces cerevisiae (yeast). The effects of pH, temperature, sugar concentration of solution, and yeast concentration are studied. The pH is varied from 1 to 8. The temperature is changed from 25 to 45℃. Sugar concentration of solution is taken from 50 to 400 g per liter. Addition of yeast is in the range of 1 to 8 g per liter. From this study the optimum pH is found to be 4. The optimum initial solution temperature is 35℃. optimum values of sugar concentration and yeast concentration are 300 and 2 g per liter respectively.

关键词： Ethanol Fermentation Molasses Yeast optimum parameters

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Study of optimum parameters for Chinese female underwire bra size system by 3D virtual anthropometric measurement

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JOURNAL OF THE TEXTILE INSTITUTE 2017年第6期108卷 877-882页

作者： Liu, Yu Wang, Jianping Istook, Cynthia L. Donghua Univ Coll Fash & Design Shanghai Peoples R China North Carolina State Univ Coll Text Raleigh NC 27695 USA

The aim of this paper is to explore the optimum parameters for Chinese female underwire bra size system. Raw data was collected for 275 subjects using a 3D scanner, and 108 measurement values were extracted by reverse engineering software Polyworks. Analysis of data was conducted by integrating the entropy weight method and Principal Component Analysis (PCA) methods. It was determined that the value of breast breadth (straight distance from inner most point to outer most point on the breast) should be added to the pivotal parameters and compared to previous research to classify the breast shape and to create a totally new size system for the underwire bra. This information can provide the value width for the pattern maker and help in choosing the right sized & shaped wire for the underwire bra. When compared to former research, more breast shapes were defined than when only the depth width ratio and under-bust girth were used as parameters.

关键词： Underwire bra optimum parameters pattern design size system virtual entropy analysis

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Choosing Classification Algorithms and Its optimum parameters based on Data Set Characteristics

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电脑学刊 2017年第5期28卷 26-38页

作者： Yang Zhongguo Li Hongqi Sikandar Ali Ao Yile

Choosing a correct classification algorithm for a given data set is an important task considering the existing multiple classifiers. A method of recommending a suitable algorithm and its optimum parameters for a given data set is proposed. Firstly, six different types of measures are computed for each data set to be representation of its characteristics. Then, the performance and optimum parameters for a given algorithm are computed by using grid search method. Afterwards, a model was built to predict the variance of classifiers for a given data set and another model was built to predict the best suitable algorithm. The proposed method tries to predict the optimum parameter for a certain algorithm based on knowledge learning from history data sets. To evaluate the performance of the proposed method, some extensive experiments for four different types of algorithms are conducted upon the UCI data sets. The results indicate that the proposed method is effective.

关键词： algorithm automatic recommendation algorithm performance data set characteristics optimum parameters

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Effect of basic parameters defining principal soil-structure interaction on seismic control of structures equipped with optimum tuned mass damper

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SOIL DYNAMICS AND EARTHQUAKE ENGINEERING 2025年 189卷

作者： Araz, Onur Gumushane Univ Dept Civil Engn Gumushane Turkiye

One of the most effective systems for reducing dynamic responses of the structures subjected to earthquake excitations is tuned mass dampers (TMDs). In the traditional design theory of TMDs, the structures are assumed to be rigidly connected to the ground. Using this approach, known as the fixed foundation approach, may lead to deterioration of the performance of the TMD in cases where soil-structure interaction (SSI) is significant. Therefore, it is crucial to consider the SSI effects to obtain the optimum parameters of the TMDs. Unlike previous studies, two key parameters (i.e., structure-to-soil stiffness ratio and aspect ratio of the structure) are considered, which define the principal SSI effects on the effectiveness of TMD. For the aspect ratio of the structure, three different values (i.e., lambda = 1, 2, and 4) are considered, these values correspond to the squat, ordinary, and slender structures representing traditional buildings, respectively. Four different values (i.e., a0 = 0, 0.5, 1, and 2) are also considered for the structure-soil stiffness ratio. This ratio being equal to 0 corresponds to the fixed foundation approach. This also demonstrates that the structure is constructed on hard rock. The optimum parameters of the TMD are obtained using the Jaya algorithm (JA). The proposed methodology is applied to three different buildings (i.e., 3-story, 6story, and 12-story), and the optimum parameters of the TMD are verified using a total of 72 ground motions corresponding to NEHRP site classes C, D, and E. Numerical results show that the effectiveness of TMD is significantly affected by the basic parameters that define the principal SSI. In addition, the efficiency of the TMD is significantly related to the characteristics of the ground motions. It has been observed that TMD does not perform adequately in reducing vibrations in low-rise buildings (i.e., lambda = 1) constructed on low-stiffness soils (i.e., a0 = 2).

关键词： optimum parameters Seismic control Seismic analysis Soil-structure interaction Tuned mass damper

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Effect of optimum parameters Setting on Laser-Induced Breakdown Spectroscopy

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SPECTROSCOPY LETTERS 2015年第6期48卷 403-410页

作者： Kadachi, Ahmed N. Al-Eshaikh, Mohammad A. King Saud Univ Coll Engn Res Ctr Riyadh 11421 Saudi Arabia

Laser-induced breakdown spectroscopy is very attractive analytical method owing to many advantages, but it is complicated by the matrix effect due to complex nature of the laser-sample and plasma-particles interaction processes. For more precise and accurate analysis results, this effect must be reduced to a minimum. The approach used in this study to reduce the matrix effect was based on the selection of the optimum parameters of the system using pure element standards, followed by data processing and various normalization techniques. The copper alloys were selected for this study knowing that these materials are particularly difficult to be analyzed by laser-induced breakdown spectroscopy due to large differences in the physical properties of the metal constituents. But the accuracy improvements obtained by the proposed approach are encouraging to generalize it to other similar materials. Eighteen reference standards of copper alloys were measured to construct the calibration curves after optimum parameter settings. The coefficients of determination, R-2, obtained from the calibration curves of most elements present in copper alloys were close to 1 (0.99). The validation of this approach was verified by extra reference standards measurement, which gives relative measurement errors varying from about 1-8% according to the inverse level of the element concentration.

关键词： LIBS analysis normalization techniques optimum parameters reduction of matrix effect

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optimum parameters OF MINING MACHINES FOR SPECIFIC CONDITIONS 14th

OPTIMUM PARAMETERS OF MINING MACHINES FOR SPECIFIC CONDITION...

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14th International Multidisciplinary Scientific Geoconference (SGEM)

作者： Fries, Jiri Hapla, Tomas Neumann, Tomas VSB Tech Univ Ostrava Inst Clean Technol Extract & Utilizat Energy Reso Ostrava Czech Republic VSB Tech Univ Ostrava Dept Prod Machines & Design Ostrava Czech Republic

ISBN: (纸本)9786197105094

In the case of the process of mechanical disintegration of mineral raw materials, the supply of a certain amount of energy, which is consumed for the separation of rock chips (elementary pieces) from the rock mass, is required. By this process, the entire cycle of mining of the economic mineral is given. The minimum energy demand of the disintegration process is achieved especially through the correct selection of a tool and the selection of optimum cutting speed and rate of tool advance into the cut, and also other parameters that have a minor impact on the very disintegration process. For the determination of optimum parameters of mining machines, a sophisticated instrument for the in-situ measurement of disintegrating forces can be used. The instrument is ATEX certified for use in a potentially methane explosive atmosphere, and thus can be used in all mines not only in the Czech Republic but also practically all over the world. The principle of the instrument consists in the in situ measurement of disintegrating forces and then the application of them to a specific machine or a mining organ.

关键词： disintegration optimum parameters mining machine

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