Early termination of a two-stage study to develop and validate a panel of biomarkers

Joseph S. Koopmeiners; Rachel Isaksson Vogel

doi:10.1002/sim.5622

Two-stage biomarker panel study and estimation allowing early termination for futility

Biostatistics ◽

10.1093/biostatistics/kxv017 ◽

2015 ◽

Vol 16 (4) ◽

pp. 799-812 ◽

Cited By ~ 1

Author(s):

Shanshan Zhao ◽

Yingye Zheng ◽

Ross L. Prentice ◽

Ziding Feng

Keyword(s):

Panel Study ◽

Early Termination ◽

Two Stage ◽

Biomarker Panel

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Identifying optimal approaches to early termination in two-stage biomarker validation studies

Journal of the Royal Statistical Society Series C (Applied Statistics) ◽

10.1111/rssc.12163 ◽

2016 ◽

Vol 66 (1) ◽

pp. 187-199 ◽

Cited By ~ 1

Author(s):

Alexander M. Kaizer ◽

Joseph S. Koopmeiners

Keyword(s):

Validation Studies ◽

Early Termination ◽

Two Stage ◽

Biomarker Validation

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Two-stage aerodynamic optimization method based on early termination of CFD convergence and variable-fidelity model

Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University ◽

10.1051/jnwpu/20213910148 ◽

2021 ◽

Vol 39 (1) ◽

pp. 148-158

Author(s):

Ji Miao ◽

Chunlin Gong ◽

Chunna Li

Keyword(s):

Optimization Method ◽

Aerodynamic Performance ◽

Early Termination ◽

Computational Time ◽

High Fidelity ◽

Aerodynamic Optimization ◽

Two Stage ◽

Optimization Stage ◽

Variable Fidelity ◽

Fidelity Model

Efficient aerodynamic design optimization method is of great value for improving the aerodynamic performance of little UAV's airfoil. Using engineering or semi-engineering estimation method to analyze aerodynamic forces in solving aerodynamic optimization problems costs little computational time, but the accuracy cannot be guaranteed. However, CFD method ensuring high accuracy needs much more computational cost, which is unfordable for optimization. Surrogate-based optimization can reduce the number of high-fidelity analyses to increase the optimization efficiency. However, the cost of CFD analyses is still huge for aerodynamic optimization due to multiple design variables, multi-optimal and strong nonlinearities. To solve this problem, a two-stage aerodynamic optimization method based on early termination of CFD convergence and variable-fidelity model is proposed. In the first optimization stage, the solutions by early termination CFD convergence and the convergenced CFD solutions are regarded as low-and high-fidelity data respectively for building variable-fidelity model. Then, the multi-island genetic algorithm is used in the global optimization based on the built variable-fidelity model. The modeling efficiency can be greatly improved due to many cheap low-fidelity data. In the second stage optimization, the global optimum from the first optimization stage is treated as the start of the Hooke-Jeeves algorithm to search locally based on convergenced CFD computations in order to acquire better-optimum. The proposed method is utilized in optimizing the aerodynamic performance of the airfoil of little UAV, and is compared with the EGO method based on single-fidelity Kriging surrogate model. The results show that the present two-level aerodynamic optimization method consumes less time.

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Conditional estimation after a two-stage diagnostic biomarker study that allows early termination for futility

Statistics in Medicine ◽

10.1002/sim.4430 ◽

2012 ◽

Vol 31 (5) ◽

pp. 420-435 ◽

Cited By ~ 17

Author(s):

Joseph S. Koopmeiners ◽

Ziding Feng ◽

Margaret Sullivan Pepe

Keyword(s):

Early Termination ◽

Diagnostic Biomarker ◽

Two Stage ◽

Conditional Estimation

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Two-stage self-seeding method for preparation of single crystals of poly(phenylene sulfide)

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100153816 ◽

1989 ◽

Vol 47 ◽

pp. 368-369

Author(s):

Sengshiu Chung ◽

Peggy Cebe

Keyword(s):

Single Crystals ◽

High Performance ◽

Dilute Solution ◽

Two Stage ◽

Annealing Behavior ◽

High Performance Polymers ◽

Seeding Method ◽

Phenylene Sulfide

We are studying the crystallization and annealing behavior of high performance polymers, like poly(p-pheny1ene sulfide) PPS, and poly-(etheretherketone), PEEK. Our purpose is to determine whether PPS, which is similar in many ways to PEEK, undergoes reorganization during annealing. In an effort to address the issue of reorganization, we are studying solution grown single crystals of PPS as model materials.Observation of solution grown PPS crystals has been reported. Even from dilute solution, embrionic spherulites and aggregates were formed. We observe that these morphologies result when solutions containing uncrystallized polymer are cooled. To obtain samples of uniform single crystals, we have used two-stage self seeding and solution replacement techniques.

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