Predictive or Explanatory Models for Aquatic Ecosystems

1984 ◽  
Vol 16 (5-7) ◽  
pp. 571-578 ◽  
Author(s):  
S Gentil

This paper presents the modelling of a small eutrophic lake of the French Alps. A mechanistic non-linear model is elaborated; this model has to be simplified in view of its identifiability study, and parameters estimates are obtained by non-linear optimization techniques. The Computer-Aided-Design package known as I.S.E.R. has been used to develop linear models describing the phytoplankton or zooplankton data. These models prove useful to understand some system properties and are really efficient for short-term forecasting.

Holzforschung ◽  
2009 ◽  
Vol 63 (3) ◽  
Author(s):  
Peng Li ◽  
Chunping Dai ◽  
Sunguo Wang

Abstract The void variation in a wood-strand composite mat during consolidation was simulated using computer-aided design, finite element analysis, and computer image processing. Compared with prior models, this simulation provided a different and more visual approach to analyzing the mat structure, particularly the void variation during consolidation. The simulated results showed similar trends to the experimental data. The size of voids in the final panel decreased with the panel density and increased with the strand thickness, whereas the relationship between the void size and the strand length was non-linear. The wood-strand density and strand thickness had a much greater effect on the non-linear void variation than the wood strand width and length. The simulated results are beneficial to improve the fundamental understanding of composite processing and performance characteristics.


1978 ◽  
Vol 175 (3) ◽  
pp. 1137-1138 ◽  
Author(s):  
K de Fonseka ◽  
B Chance

The kinetics of reaction of reduced cytochrome a3 and CO are re-investigated by non-linear optimization techniques. When photolysis by the monitoring light is taken into account, the experimental data are best fitted by a single-intermediate mechanism.


Author(s):  
Najib Mahdi ◽  
Stephane Bila ◽  
Serge Verdeyme ◽  
Michel Aubourg ◽  
Khaled Khoder ◽  
...  

This paper outlines an original shape optimization library backed by a three dimensional (3D) full-wave electromagnetic (EM) simulator, combining several efficient structural optimization techniques and suitable for viable computer-aided design (CAD) of complex microwave components. The microwave components are modeled by finite element method (FEM) and their dimensions and shape are optimized using four techniques: design of experiments (DOE), level-set method (LS), topology gradient (TG) method, and genetic algorithm (GA). The various methods allow determining the optimal geometry, shape or topology of 2D or 3D objects within the microwave device, by minimizing iteratively a cost function related to the desired specifications. Typical demonstration illustrates the versatility of the proposed library based on the design of a dual mode dielectric resonator filter in order to improve its unloaded quality factor by keeping the same frequency isolation, their accuracy and efficiency are verified by the available measured results.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Abhishek Gupta ◽  
Dwijendra Nath Dwivedi ◽  
Ashish Jain

Purpose Transaction monitoring system set up by financial institutions is one of the most used ways to track money laundering and terrorist financing activities. While being effective to a large extent, the system generates very high false positives. With evolving patterns of financial transactions, it also needs effective mechanism for scenario fine-tuning. The purpose of this paper is to highlight quantitative method for optimizing scenarios in money laundering context. While anomaly detection and unsupervised learning can identify huge patterns of false negatives, that can reveal new patterns, for existing scenarios, business generally rely on judgment/data analysis-based threshold finetuning of existing scenario. The objective of such exercises is productivity rate enhancement. Design/methodology/approach In this paper, the authors propose an approach called linear/non-linear optimization on threshold finetuning. This traditional operations research technique has been often used for many optimization problems. Current problem of threshold finetuning for scenario has two key features that warrant linear optimization. First, scenario-based suspicious transaction reporting (STR) cases and overall customer level catch rate has a very high overlap, i.e. more than one scenario captures same customer with different degree of abnormal behavior. This implies that scenarios can be better coordinated to catch more non-overlapping customers. Second, different customer segments have differing degree of transaction behavior; hence, segmenting and then reducing slack (redundant catch of suspect) can result in better productivity rate (defined as productive alerts divided by total alerts) in a money laundering context. Findings Theresults show that by implementing the optimization technique, the productivity rate can be improved. This is done through two drivers. First, the team gets to know the best possible combination of threshold across scenarios for maximizing the STR observations better coverage of STR – fine-tuned thresholds are able to better cover the suspected transactions as compared to traditional approaches. Second, there is reduction of redundancy/slack margins on thresholds, thereby improving the overall productivity rate. The experiments focused on six scenario combinations, resulted in reduction of 5.4% of alerts and 1.6% of unique customers for same number of STR capture. Originality/value The authors propose an approach called linear/non-linear optimization on threshold finetuning, as very little work is done on optimizing scenarios itself, which is the most widely used practice to monitor enterprise-wide anti-money laundering solutions. This proves that by adding a layer of mathematical optimization, financial institutions can additionally save few million dollars, without compromising on their STR capture capability. This hopefully will go a long way in leveraging artificial intelligence for further making financial institutions more efficient in controlling financial crimes and save some hard-earned dollars.


2008 ◽  
Vol 14 (1) ◽  
pp. 61-66 ◽  
Author(s):  
Algirdas Juozapaitis ◽  
Remigijus Kutas ◽  
Donatas Jatulis

Paper is assigned to numerical analysis peculiarities of masts applying specialised computer‐aided design packages. Mast's deformable behaviour is described as non‐linear one. The test problem of mast is solved by two widely applied in Lithuania computational packages STAADpro and Robot Millennium and the specialised programme for mast design SUDM. A corrected analytical method for mast guy analysis, taking into account a force component, acting along the guy supports. A performed numerical experiment is aimed to clarify the possibilities of the above‐mentioned numerical analysis instruments for geometrical non‐linear modelling of structure. The accuracy errors when determining the mast stress and strain fields by numerical analysis packages comparing with the ones obtained by a corrected analytical method are indicated. Possibilities of employing the considered computer‐aided design programming packages for practical design of masts are discussed. Santrauka Straipsnyje aptariami stiebų kaip netiesiškai deformuojamų konstrukcinių sistemų skaičiavimo ypatumai naudojant kompiuterinio projektavimo specializuotus programinius paketus. Sprendžiamas stiebo elgsenos analizės ir skaičiavimo uždavinys pasitelkiant dvi plačiai Lietuvoje taikomas statybinių konstrukcijų kompiuterinio projektavimo programas STAADpro ir Robot Millennium bei specializuotą stiebų skaičiavimo programą SUDM. Straipsnyje pateikiama ir patikslinta analizinė stiebo atotampos skaičiavimo metodika, rodanti apkrovos komponentę, veikiančią išilgai atotampos atramų. Remiantis atliktu skaitiniu eksperimentu, yra sprendžiama apie minėtųjų kompiuterinio projektavimo programinių paketų galimybes modeliuoti geometriškai netiesinės sistemos elgseną. Nurodomos šių programinių paketų stiebų elementų įrąžų bei poslinkių apskaičiavimo lyginant su patikslinta analizine skaičiavimo metodika paklaidos, aptariamos minėtųjų kompiuterinio projektavimo programų praktinio taikymo stiebams skaičiuoti galimybės.


1989 ◽  
Vol 111 (2) ◽  
pp. 285-289 ◽  
Author(s):  
C. S. Jog ◽  
S. S. Pande

This paper presents the design strategy for the Computer-Aided Design (CAD) of compact helical gear sets. Using optimization techniques, fundamental gear design parameters such as the number of teeth on the pinion, helix angle, and diametral pitch (or module) are selected subject to constraints on bending stresses, contact stresses, and involute interference limits for both standard and nonstandard gearing. The CAD procedure is illustrated with the help of a design example.


2021 ◽  
Vol 11 (22) ◽  
pp. 10980
Author(s):  
Enrico Dalpadulo ◽  
Fabio Pini ◽  
Francesco Leali

The use of Topology Optimization techniques has seen a great development since the last decade. The principal contributor to this trend is the widespread use of Additive Manufacturing technologies to effectively build complex and performant structures over different settings. Nevertheless, the use of Topology Optimization in Design for Additive Manufacturing processes is not simple and research aims to fill the gap between theory and practice by evolving at the same time both approaches, workflows, and design software that allow their implementation. Since a strong connection between methodologies and tools exists, this work proposes a method to assess computer-aided design tools or platforms. This can be applied to sustain the key phase for selection and adoption of the computer-aided tools in industrial settings embracing Additive Manufacturing. The workflow for Topology Optimization implementation, the structure of the proposed evaluation approach, and its application, are presented to demonstrate effective usability. The automotive case study is the redesign of internal combustion engine piston to benefit of metal Additive Manufacturing based enhanced product performance. A preliminary finite element model is defined and a Topology Optimization based redesign is concurrently set up through four different commercial computer-based platforms. The method accounting for the assessment of required operations for the design optimization is applied to perform the tools selection phase.


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