scholarly journals Optimization for the Assessment of Spudcan Peak Resistance in Clay–Sand–Clay Deposits

2021 ◽  
Vol 9 (7) ◽  
pp. 689
Author(s):  
Jingbin Zheng ◽  
Shaoqing Zhang ◽  
Dong Wang ◽  
Jun Jiang
Keyword(s):  
Predictive Model ◽  
Parameter Optimization ◽  
Optimization Technique ◽  
Optimization Procedure ◽  
Penetration Resistance ◽  
Centrifuge Tests ◽  
Clay Deposits ◽  
Application Procedure ◽  
Stress Dependent ◽  
Peak Resistance

Clay–sand–clay deposits are commonly encountered in the offshore field. For spudcan installation in this soil stratigraphy, the potential for punch-through exists, with the peak penetration resistance formed within the interbedded sand layer. Therefore, a careful assessment of the penetration resistance profile has to be performed. Based on the recently proposed failure-stress-dependent model, this paper presents a modified predictive model for estimating the peak resistance. The modified model incorporates the bearing capacity depth factor and the protruded soil plug in the bottom clay layer into the formulation. It is proven that the modified predictive model provides improved deterministic estimations for the peak resistances measured in centrifuge tests. Based on the modified predictive model, a parameter optimization technique is utilized to optimize the prediction of peak resistance using penetration resistances observed beforehand. A detailed application procedure is proposed and applied to the centrifuge tests accumulated from existing publications, with further improvement on the predictions demonstrated. The proposed parameter optimization procedure combined with the modified predictive model provides an approach to perform real-time optimization for assessing spudcan peak resistance in clay–sand–clay deposits.

scholarly journals Predicting the resistance profile of a spudcan penetrating sand overlying clay

2014 ◽  
Vol 51 (10) ◽  
pp. 1151-1164 ◽  
Author(s):  
Pan Hu ◽  
Dong Wang ◽  
Mark J. Cassidy ◽  
Sam A. Stanier
Keyword(s):  
Penetration Resistance ◽  
Clay Layer ◽  
Interface Shear ◽  
Element Analysis ◽  
Resistance Profile ◽  
Dense Sand ◽  
Geotechnical Centrifuge ◽  
Centrifuge Tests ◽  
Full Penetration ◽  
Stress Dependent

Assessment of the risk of punch-through failure of spudcan foundations on sand overlying clay requires prediction of the full penetration resistance profile, from touchdown and through punch-through to equilibrium of the vertical resistance at depth in the underlying clay layer. This study uses the Coupled Eulerian–Lagrangian approach, a large deformation finite element analysis method, to model the complete penetration resistance profile of a spudcan on sand overlying clay. The sand is modeled using the Mohr–Coulomb model, while the clay is modeled using a modified Tresca model to account for strain softening. The numerical method is then used to simulate a series of spudcan penetration tests, performed in a geotechnical centrifuge, on medium dense sand overlying clay. The punch-through behavior observed in the experiments is replicated, and the penetration resistance profiles from numerical analyses are generally a reasonable match to the experimental measurements. The influences of the sand layer height to foundation diameter ratio, sand–clay interface shear strength, and strength gradient in clay on the penetration resistance profiles are explored in a complementary parametric study. The penetration resistance in the underlying clay layer is well predicted using a simple linear expression for the bearing capacity factor for the spudcan and underlying sand plug. This expression is combined with an existing failure stress dependent model for predicting peak resistance to form a simplified method for prediction of the full penetration resistance profile. This new method provides estimates of the vertical penetration that the spudcan will run during the punch-through event. It is validated against both medium dense and dense sand centrifuge tests.

Primena Lagranžove optimizacije na problematiku proizvodnje energije iz obnovljivih izvora

2020 ◽  
Vol 22 (1-2) ◽  
pp. 145-152
Author(s):  
Vladan Ristić ◽  
◽  
Nikola Rajaković
Keyword(s):  
Power Plants ◽  
Production Systems ◽  
Optimization Technique ◽  
Optimization Procedure ◽  
Sole Source ◽  
Renewable Sources ◽  
Hydro Power ◽  
Ecological Awareness ◽  
Hydro Power Plants ◽  
Feed In Tariff

The apparent increase of ecological awareness during the previous decade has led to the need for adaptation of numerous areas of everyday human lives, so they fit the newly developed environmental tendencies. One of the areas in which this necessity was prominent was the power engineering, where, above all, the understanding of production systems was affected, with the turnabout regarding the distancing from the conventional sources and inclining towards the more acceptable renewable sources taking place. However, alongside the undeniable ecological sustainability of these sources, the financial sustainability of their utilization needs to be considered as well, which is why the subject of this paper is the minimization of costs of energy production in these capacities, if the fictious demand area needed to be supplied. It was assumed that this area is separated from transmission and distribution network, with the sole source of energy for the analyzed consumption being the wind, solar and hydro power plants, located in the close vicinity of the examined area. As the objective of the optimization, performed by the method of Lagrange multipliers, the appropriate apportioning of the generation powers in these plants for every hour during the year was selected, so the total yearly costs of supplying the demand were as low as possible. Also, considering the currently promoted methods intended for encouragement of the potential investors to proceed with the projects that encompass renewable sources, the different cases for which the share of renewables included in the feed-in tariff was varied. Finally, in order to provide the full insight into the optimization procedure, for the randomly selected hour of the year and share of feed-in tariff in the generation capacities, the process of calculation of production powers in the described plants and multipliers needed for application of the selected optimization technique was enclosed.

An On-Line Interactive Microcomputer-Based Parameter Optimization Technique

1981 ◽  
Vol IECI-28 (4) ◽  
pp. 370-375
Author(s):  
James A. Heinen ◽  
Russell J. Niederjohn ◽  
Teresa A. Buckley Stumpf
Keyword(s):  
Parameter Optimization ◽  
Optimization Technique ◽  
On Line

A New Approach on Mounting Systems Optimization

2003 ◽  
Author(s):  
Reza Madjlesi ◽  
Amir Khajepour ◽  
Brad Schubert ◽  
Fathy Ismail
Keyword(s):  
Path Analysis ◽  
Optimization Technique ◽  
Optimization Procedure ◽  
System Optimization ◽  
Optimization Method ◽  
Trial And Error ◽  
Target Response ◽  
New Approach ◽  
Weakly Coupled ◽  
Noise Vibration

Vehicles are assemblies of subsystems or modules, which are developed in parallel at multiple locations and often for more than one vehicle. CAE software provides the integration of modules in a complete vehicle in parallel; however the whole system requires final adjustments and tunings. These adjustments, especially in suspensions and mounting systems are very time consuming and are generally based upon trial and error techniques. To reduce the number of trials, usually noise path analysis (NPA) is used. In this technique, the noise and vibration paths for each mount to the objective point are measured. Using the measured data, the dominant path is detected. A highly experienced NVH engineer now can use the information to tune the mount to satisfy the target response. This technique is appropriate if the subsystems are weakly coupled. This situation is not usually the case in engine mounting systems where any modification in one of the mounts may change the dominant path. An important step to reduce refinement time is to develop a method to obtain the overall model of the whole vehicle. In this paper, we introduce a new approach in vehicle’s NVH development. In this approach, the model of the vehicle for mounting system optimization is obtained based on the FRF synthesis. A hybrid analytical/experimental model of the vehicle is developed to predict the NVH response of the vehicle for any given mounting system. This model along with an optimization technique is used to arrive at the optimum mounting system for any objective function. The optimization method is linked with the noise path analysis (NPA), which is used to specify the dominant directions that the noise/vibration is transferred to the response point. These directions are used in the optimization procedure to find the optimum mounting system with minimum calculation time. Experimental results on a full size car are presented to evaluate new approach.

Optimum Positioning of Ports in the Limaçon Gas Expanders

2011 ◽  
Vol 133 (10) ◽  
Author(s):  
Ibrahim A. Sultan ◽  
Carl G. Schaller
Keyword(s):  
System Performance ◽  
Optimization Technique ◽  
Optimization Procedure ◽  
Operating Parameters ◽  
Phase Flow ◽  
Two Phase ◽  
Positive Displacement ◽  
Micropower Generation ◽  
Insight Into

Positive displacement expanders are quickly gaining popularity in the fields of micropower generation and refrigeration engineering. Unlike turbomachines, expanders can handle two-phase flow applications at low speed and flow rate levels. This paper is concerned with a simple-design positive displacement expander based on the limaçon of Pascal. The paper offers an insight into the thermodynamic workings of the limaçon gas expander and presents a mathematical model to describe the manner in which the port locations affect the expander performance. A stochastic optimization technique is adopted to find the locations, for the expander ports, which produce best expander performance for given chamber dimensions. The operating speed and other parameters will be held constant during the optimization procedure. A case study is offered in this paper to prove the validity of the presented approach, and comments are given on how various operating parameters affect system performance in the limaçon design.

Design of Digital Feedforward/Preview Controllers for Processes With Predetermined Feedback Controllers

1980 ◽  
Vol 102 (4) ◽  
pp. 218-225 ◽  
Author(s):  
Masayoshi Tomizuka ◽  
D. H. Fung
Keyword(s):  
Parameter Optimization ◽  
Design Method ◽  
Optimization Technique ◽  
Feedback Controller ◽  
Weighted Sum ◽  
Feedback Controllers ◽  
Quadratic Cost ◽  
Cost Criterion ◽  
Integral Action ◽  
Process Output

This paper deals with the design of digital feedforward/preview (F/P) controllers for multi-input, multi-output processes with predetermined feedback controllers. The feedback controller is assumed to include an integral action which operates upon the error between setpoint and process output. The feedforward/preview controller is a weighted sum of previewed values of future disturbances. Formula for the F/P control gains are derived using a parameter optimization technique to minimize a quadratic cost criterion. Simulation examples are included to show some of the consequences of the developed design method.

scholarly journals Optimization of Natural Frequencies and Sound Power of Beams Using Functionally Graded Material

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Nabeel T. Alshabatat ◽  
Koorosh Naghshineh
Keyword(s):  
Volume Fraction ◽  
Optimization Technique ◽  
Sound Radiation ◽  
Optimization Procedure ◽  
Functionally Graded ◽  
Lumped Parameter Model ◽  
Acoustic Properties ◽  
Sound Power ◽  
Material Distribution ◽  
Fgm Beam

This paper presents a design method to optimize the material distribution of functionally graded beams with respect to some vibration and acoustic properties. The change of the material distribution through the beam length alters the stiffness and the mass of the beam. This can be used to alter a specific beam natural frequency. It can also be used to reduce the sound power radiated from the vibrating beam. Two novel volume fraction laws are used to describe the material volume distributions through the length of the FGM beam. The proposed method couples the finite element method (for the modal and harmonic analysis), Lumped Parameter Model (for calculating the power of sound radiation), and an optimization technique based on Genetic Algorithm. As a demonstration of this technique, the optimization procedure is applied to maximize the fundamental frequency of FGM cantilever and clamped beams and to minimize the sound radiation from vibrating clamped FGM beam at a specific frequency.

3-D implicit finite‐difference migration by multiway splitting

Geophysics ◽  
1997 ◽  
Vol 62 (2) ◽  
pp. 554-567 ◽  
Author(s):  
Dietrich Ristow ◽  
Thomas Rühl
Keyword(s):  
Finite Difference ◽  
Power Series ◽  
Taylor Expansion ◽  
Optimization Technique ◽  
Optimization Procedure ◽  
Finite Difference Schemes ◽  
Difference Operators ◽  
Square Root ◽  
Implicit Finite Difference ◽  
Root Operator

We show that 3-D implicit finite‐difference schemes can be realized by multiway splitting in such a way that the steep dip problem and the problem of numerical anisotropy are overcome. The basic idea is as follows. We approximate the 3-D square root operator by a sequence of 2-D operators in three, four, or six directions to solve the azimuth symmetry problem. Each 2-D square root operator is then approximated by a sequence of implicit 2-D operators to improve steep dip accuracy. This sequence contains some unknown coefficients, which are calculated by a Taylor expansion technique or by an optimization technique. In the Taylor expansion method, the square root and its approximation are expanded into power series. By comparing the terms, the unknown coefficients are calculated. The more 2-D finite‐difference operators for cascading are taken and the more directions for downward continuation are chosen, the more terms from power series can be compared to obtain a higher‐degree migration operator with better circular symmetry. In the second method, optimized coefficients are calculated by an optimization procedure whereby a variation of all unknown coefficients is performed, in such a way that both the sum of all deviations between the correct square root and its approximation and the sum of all deviations from azimuth symmetry are minimized. A mathematical criterion for azimuth symmetry has been defined and incorporated into the opfimization procedure.

Modelling the Installation of Stiffened Caissons in Overconsolidated Clay

2009 ◽  
Author(s):  
Z. J. Westgate ◽  
L. Tapper ◽  
B. M. Lehane ◽  
C. Gaudin
Keyword(s):  
Structural Engineering ◽  
Penetration Resistance ◽  
Measured Data ◽  
Resistance Factors ◽  
Centrifuge Tests ◽  
Current Design ◽  
Horizontal Stiffener ◽  
Flow Round ◽  
Suction Caissons ◽  
Overconsolidated Clay

Design of suction caissons for installation in overconsolidated clay presents several geotechnical engineering challenges. These include (i) predicting the installation resistance and required ‘suction’ pressure, (ii) ensuring adequate skirt length to account for vertical plug heave, and (iii) accommodating the structural engineering stiffening requirements and their effects on the penetration resistance and plug heave. A suite of centrifuge tests in overconsolidated kaolin clay was carried out to investigate the effects of stiffener geometry on penetration resistance during direct jacking and suction installation. Three caisson geometries were compared: caissons with (i) no stiffeners, (ii) horizontal stiffeners only and (iii) both vertical and horizontal stiffeners. Results show negligible differences in penetration resistance between jacked and suction installation for each caisson type. The magnitude of soil heave within the caisson is seen to be highly dependent on the level of applied suction as well as on the volume of the stiffeners. Observations during and following testing indicated that minimal flow-round of the overconsolidated clay occurred for skirts with horizontal stiffeners. These included (i) linear penetration resistance profiles following penetration of the lowest horizontal stiffener, (ii) a wedge of clay observed only below the lowest horizontal stiffener following extraction, and (iii) unsupported plug heave heights following penetration. A comparison of measured data with back-calculated resistance factors suggests that current design methods adequately predict the measured penetration resistance assuming zero flow-round conditions, implying additional end bearing of the upper horizontal stiffener during penetration was negligible.

Parameter Optimization for a Polymer Electrolyte Membrane Fuel Cell Model

2010 ◽  
Vol 37-38 ◽  
pp. 834-838
Author(s):  
Xin Li ◽  
Qun Yan ◽  
Da Tai Yu
Keyword(s):  
Fuel Cell ◽  
Power Systems ◽  
Parameter Optimization ◽  
High Performance ◽  
Cell Model ◽  
Polymer Electrolyte Membrane ◽  
Optimization Technique ◽  
Cell System ◽  
Empirical Models ◽  
Semi Empirical

The accurate mathematical model is an important tool for simulation and design analysis of fuel cell power systems. Semi-empirical models are easier to be obtained and can also be used to accurately predict the performance of fuel cell system for engineering applications. Particle swarm optimization (PSO) is a recently invented high-performance algorithm. In this paper, a parameter optimization technique of PEMFC semi-empirical models based on DKPSO was proposed in terms of the voltage-current characteristics. The simulated and experimental data confirmed the validity of the optimization technique, and indicated that PSO is an effective tool for optimizing the parameters of PEMFC models.

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