scholarly journals A Sequential Optimization Sampling Method for Metamodels with Radial Basis Functions

2014 ◽  
Vol 2014 ◽  
pp. 1-17 ◽  
Author(s):  
Guang Pan ◽  
Pengcheng Ye ◽  
Peng Wang ◽  
Zhidong Yang
Keyword(s):  
Engineering Design ◽  
Density Function ◽  
Sampling Method ◽  
Sampling Methods ◽  
Basis Functions ◽  
Sequential Optimization ◽  
Numerical Examples ◽  
Sampling Points ◽  
Computationally Expensive ◽  
Minimum Points

Metamodels have been widely used in engineering design to facilitate analysis and optimization of complex systems that involve computationally expensive simulation programs. The accuracy of metamodels is strongly affected by the sampling methods. In this paper, a new sequential optimization sampling method is proposed. Based on the new sampling method, metamodels can be constructed repeatedly through the addition of sampling points, namely, extrema points of metamodels and minimum points of density function. Afterwards, the more accurate metamodels would be constructed by the procedure above. The validity and effectiveness of proposed sampling method are examined by studying typical numerical examples.

Engineering Design Based on Hammersley Sequences Sampling Method and SVR

2012 ◽  
Vol 544 ◽  
pp. 206-211 ◽  
Author(s):  
Li Ke ◽  
Hao Bo Qiu ◽  
Zhen Zhong Chen ◽  
Li Chi
Keyword(s):  
Engineering Design ◽  
Surrogate Model ◽  
Sampling Method ◽  
Simulation Analysis ◽  
Design Method ◽  
Computational Cost ◽  
Simulation Design ◽  
Fem Method ◽  
Computationally Expensive ◽  
Sample Method

Nowadays, computer-based engineering design is becoming widely used in the design of products. In the field of engineering, CAD model, FEM method and surrogate model are used to reduce the time and computational cost comparing with the traditional engineering design. But when facing with computationally expensive tasks, such design method mentioned above seems unable to deal with such tasks. In that case, surrogate model is gradually used and shows great potential in dealing with the computationally complex tasks. Although computing power and speed are rapidly growing, the use of the computer simulation analysis is limited in doing engineering design and some other analysis such as reliability analysis for complex product, so that it limits the use of metamodeling techniques. In that case, we use space-filling DOE sample method to support the construction of surrogate model. In this paper, we consider both Hammersley sequences and SVM as sampling method and surrogate model to construct the simulation design model, aiming at reduce computational costs. SVR achieves more accuracy and shows great potential in application in the design of complex and computationally expensive tasks.

scholarly journals Diversity of parasitoid Hymenoptera in banana germplasm plantation Yogyakarta

2019 ◽  
Vol 23 (1) ◽  
pp. 26
Author(s):  
Ichsan Luqmana Indra Putra
Keyword(s):  
Sampling Method ◽  
Sampling Methods ◽  
Direct Method ◽  
Wiener Index ◽  
Sampling Point ◽  
Sampling Points ◽  
Index Value ◽  
Number Of Individuals ◽  
Pan Traps

Banana is one of the fruits in Indonesia. The development of its production in Indonesia has increased. However, there are several factors that can reduce the production, one of which is pests. Pests on bananas can be controlled with natural enemies, one of which is parasitoid. The study aimed to calculate the diversity and abundance of parasitoids in the Yogyakarta banana germplasm plantation. The research was carried out in an area of approximately 2 Ha from April to June 2018 with sampling taken once a week. Sampling method used was in the form of transect. The determination of the transect point is determined as far as 500m between sampling points. At each sampling point carried out 2 sampling methods. Direct method by taking pests on 3 banana plants at each point and indirect with insect net and yellow pan traps. The results found that Shannon-Wiener Index value was 3.29. 22 Hymenoptera parasitoid families were found with the highest morphospecies were superfamily Chalcidoidea and the highest number of individuals were Scelionidae.

Non-Probabilistic Sampling in Quantitative Clinical Research

2022 ◽  
Vol 7 (1) ◽  
pp. 0-0
Keyword(s):  
Best Practices ◽  
Quantitative Research ◽  
Sampling Method ◽  
Sampling Methods ◽  
Early Career ◽  
Probability Sampling ◽  
Probabilistic Sampling ◽  
Quantitative Studies ◽  
Health Studies ◽  
Probabilistic Sample

Quantitative researchers need a probabilistic sample to generalise their findings, but research constraints often compel them to use non-probabilistic samples. The use of non-probability sampling methods in quantitative studies has therefore become a norm. Interestingly, even studies published in top-quality journals compromise best practices that the use of non-probabilistic samples requires. Based on a thorough review of relevant studies, we developed a typology of non-probability sampling methods used in quantitative health studies. An attempt was made to discuss the limit of inference under each type of non-probability sampling method. Non-probability sampling in quantitative research was also delineated as a way to maximise response rate. This study is expected to guide students and early career epidemiologists to understand how to apply non-probabilistic sampling methods in quantitative approaches and plausibly document or report their chosen methods.

Digital instruments for reporting of gastrointestinal symptoms in clinical trials: comparison of end-of-day diaries versus experience sampling method (Preprint)

2021 ◽  
Author(s):  
Abraham B. Beckers ◽  
Johanna T.W. Snijkers ◽  
Zsa Zsa R.M. Weerts ◽  
Lisa Vork ◽  
Tim Klaassen ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Randomized Controlled Trial ◽  
Irritable Bowel Syndrome ◽  
Sampling Method ◽  
Sampling Methods ◽  
Controlled Trial ◽  
Smartphone Application ◽  
Randomized Controlled ◽  
Pre Treatment ◽  
Irritable Bowel

BACKGROUND Questionnaires are necessary tools for assessing symptoms of disorders of the brain-gut interaction in clinical trials. We previously reported on the excellent compliance to a smartphone app used as symptom diary in a randomized clinical trial in irritable bowel syndrome (IBS). Other sampling methods, such as the experience sampling method (ESM), are better equipped to measure symptom variability over time, provide useful information regarding possible symptom triggers and are free of ecological and recall bias. The high frequency of measurements, however, could limit the feasibility of ESM in clinical trials. OBJECTIVE This study aimed to compare compliance rates of a smartphone-based end-of-day diary and ESM for symptom assessment in irritable bowel syndrome and functional dyspepsia (FD). METHODS Data from four studies were included. Patients with IBS participated in a randomized controlled trial, which involved a smartphone end-of-day diary of 2+8 weeks (pre-treatment + treatment period), and an observational study, during which patients completed ESM assessments using a smartphone application for one week. Patients with FD participated in a randomized controlled trial, which involved a smartphone end-of-day diary of 2+12 weeks (pre-treatment + treatment period), and an observational study, during which patients completed ESM assessments using a smartphone application for one week. Compliance rates were compared between these two symptom sampling methods. RESULTS Twenty-five patients with IBS and fifteen patients with FD were included. Overall compliance rates for the end-of-day diaries were significantly higher than for ESM (IBS: 92.7% versus 69.8%, FD: 90.1% versus 61.4%, respectively). CONCLUSIONS We here demonstrate excellent compliance rates for smartphone application-based end-of-day diaries as used in two separate clinical trials. Overall compliance rates for ESM were significantly lower, rendering it more suitable for intermittent sampling periods rather than continuously during longer clinical trials.

Sampling Methods and Frozen Storage of Samples for Detection of Campylobacter jejuni on Freshly Processed Broiler Carcasses

1983 ◽  
Vol 46 (6) ◽  
pp. 510-513 ◽  
Author(s):  
L. C. BLANKENSHIP ◽  
S. E. CRAVEN ◽  
J. Y. CHIU ◽  
G. W. KRUMM
Keyword(s):  
Campylobacter Jejuni ◽  
Sampling Method ◽  
Sampling Methods ◽  
Frozen Storage ◽  
Test Tube ◽  
Tissue Samples ◽  
Defibrinated Sheep Blood ◽  
Cryoprotective Agents ◽  
Plastic Bags ◽  
Sampling Locations

Swab, rinse and excision sampling methods are commonly used for detection of microorganisms on poultry carcasses. Swabbing has been the most frequently reported sampling method for Campylobacter jejuni on poultry. We evaluated the three methods for C. jejuni detection on freshly processed poultry in the following ways: (a) the interior and exterior surfaces of half of a carcass were each thoroughly rubbed with separate swabs which were combined in a test tube containing 2 ml of appropriate medium; (b) 25 g of skin and tissue samples from neck and abdominal opening cut areas were deposited in a stomacher bag with 5 ml of brucella broth (BB) and stomached for 2 min; and (c) half carcasses were shaken for 1 min with 100 ml BB in plastic bags. One drop of each sample was streaked for isolation on brucella agar containing 10% defibrinated sheep blood and Skirrow antibiotics. Isolates were identified by microscopy and appropriate cultural tests. All three sampling techniques were essentially equivalent for detection of C. jejuni on fresh carcasses. However, when samples were stored frozen for 7 to 10 d to simulate transport conditions from sampling locations to the laboratory, the incidence of detection was significantly reduced. Use of cryoprotective agents was an effective method to preserve swab samples during frozen storage.

Possibility-Based Multidisciplinary Design Optimization in the Framework of Sequential Optimization and Reliability Assessment

2009 ◽  
Author(s):  
Xudong Zhang ◽  
Hong-Zhong Huang ◽  
Shengkui Zeng ◽  
Zhili Wang
Keyword(s):  
Design Optimization ◽  
Engineering Design ◽  
Multidisciplinary Design Optimization ◽  
High Reliability ◽  
Reliability Assessment ◽  
Coupled Systems ◽  
Multidisciplinary Design ◽  
Sequential Optimization ◽  
Sufficient Information ◽  
Early Design

Reliability Based Multidisciplinary Design Optimization (RBMDO) has received increasing attention to reach high reliability and safety in complex and coupled systems. In early design of such systems, however, information is often not sufficient to construct the precise probabilistic distributions required by the RBMDO and consequently RBMDO can not be carried out effectively. The present work proposes a method of Possibility Based Multidisciplinary Design Optimization (PBMDO) within the framework of the Sequential Optimization and Reliability Assessment (PBMDO-SORA). The proposed method enables designers to solve MDO problems without sufficient information on the uncertainties associated with variables, and also to efficiently decrease the computational demand. The efficiency of the proposed method is illustrated with an engineering design.

Free Vibration Analysis of Cable Structures Using Isogeometric Approach

2017 ◽  
Vol 14 (03) ◽  
pp. 1750033 ◽  
Author(s):  
Son Thai ◽  
Nam-Il Kim ◽  
Jaehong Lee
Keyword(s):  
Free Vibration ◽  
Vibration Analysis ◽  
Penalty Method ◽  
Natural Frequencies ◽  
Free Vibration Analysis ◽  
Basis Functions ◽  
Displacement Fields ◽  
Numerical Examples ◽  
B Splines ◽  
Cable Structures

This paper presents a free vibration analysis of cable structures based on the isogeometric approach. The nonuniform rational B-splines (NURBS) basis functions are employed to represent both the exact geometry of cable and displacement fields. In order to enrich the basis functions, the [Formula: see text]-, [Formula: see text]- and [Formula: see text]-refinement strategies are implemented. Therefore, these refinement schemes increase the accuracy of solution fields. For determining the static configuration of slack cables as a reference configuration, the well-known penalty method is used. Three numerical examples for slack and taut cable structures are presented in which different refinement schemes are utilized to obtain the converged results. The accuracy and reliability of the present numerical method are verified by comparing the natural frequencies with the results given by other researchers.

DIV-CURL WEIGHTED MINIMIZING SPLINES

2007 ◽  
Vol 05 (02) ◽  
pp. 95-122 ◽  
Author(s):  
M. N. BENBOURHIM ◽  
A. BOUHAMIDI
Keyword(s):  
Vector Field ◽  
Radial Basis Functions ◽  
Thin Plate ◽  
Approximation Problem ◽  
Scattered Data ◽  
Scalar Function ◽  
Basis Functions ◽  
Thin Plate Splines ◽  
Numerical Examples ◽  
Radial Basis

The paper deals with a div-curl approximation problem by weighted minimizing splines. The weighted minimizing splines are an extension of the well-known thin plate splines and are radial basis functions which allow the approximation or the interpolation of a scalar function from given scattered data. In this paper, we show that the theory of the weighted minimizing splines may also be used for the approximation or for the interpolation of a vector field controlled by the divergence and the curl of the vector field. Numerical examples are given to show the efficiency of this method.

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