•Evaluation on the dynamic performance of a super-tall structure is presented.•Proposed one-way FSI technique provide similar structural response to experimental.•Strong vortex induced vibrations are ...observed at critical reduced velocity.•Two-way FSI not feasible to measure structural response and require high CPU time.•Polyhedral mesh is suitable to estimate circulation flows at reduced mesh count.
This paper presents a comprehensive analysis on a super-tall structure where a numerical approach is used to measure its structural response when subjected to turbulent wind. The aim of this study is to provide a feasible alternate approach, to the experimental multi-degree of freedom (MDOF) aeroelastic wind tunnel tests, which are commonly used in industry to estimate structural responses of super-tall structures. An innovative and time-efficient uncoupled one-way Fluid-Structure Interaction (FSI) simulation technique was used to measure the structural response. This novel method was evaluated against a commercially available two-way FSI analysis technique and validated with an experimental MDOF aeroelastic model. It is shown that the uncoupled one-way FSI analysis is capable of estimating structural responses and provides similar numerical accuracy to that of the experimental response. This performance was achieved in a total of 74clock hours which accounts for the CFD simulation and transient structural analysis calculated for eighteen different structural configurations. In comparison, the two-way FSI analysis, which uses a commercial code, took 4800clock hours to calculate for six configurations. The uncoupled one-way FSI technique also provided good correlations with experimentally observed trends such as vortex-induced resonance. In comparison the two-way FSI simulation was not as accurate due to the practical limitations (such as mesh size) that needed to be introduced in order to obtain results within a feasible time frame. Finally through validation, it is demonstrated that the proposed uncoupled one-way FSI analysis technique can provide accurate results at a feasible cost.
Incorporating Graphene Oxide (GO) in concrete composite has been a good alternative to Pristine Graphene due to its hydrophilic nature and its ability to readily disperse in water the consequent ...cementitious mix. The addition of GO to the cementitious mix has been found to enhance mechanical properties. This paper aims to assess the abrasion resistance of GO incorporated concrete for its application in road pavement design. Experiments for strength in terms of compression, workability in terms of slump and abrasion resistance in accordance with ASTM-C418-20 using a sand-blasting rig are presented in the paper. It is shown that the addition of GO at percentages between 0% to 0.08% (to cement weight ratio), the compressive strength improves by 39% and 26% at 7 days and 28 days, respectively. The addition of GO consequently affected the workability where it was found that the addition of polycarboxylate ether (PCE) (superplasticisers) can drastically improve the workability, which is essential in practical applications. The abrasion was measured for specimens prepared with a high GO percentage between 0.1% to 0.3% and measured at 7 days and displayed a reduction of 70% of abraded volume at 0.3% GO. Finally, the study presents the benefits of using GO where the reduced amount of cement usage will consequently lead to sustainable concrete construction.
Recent years have seen a widespread proliferation of available in-room image guidance systems for radiation therapy target localization with many centers having multiple in-room options. In this ...session, available imaging systems for in-room IGRT will be reviewed highlighting the main differences in workflow efficiency, targeting accuracy and image quality as it relates to target visualization. Decision-making strategies for integrating these tools into clinical image guidance protocols that are tailored to specific disease sites like H&N, lung, pelvis, and spine SBRT will be discussed.
Learning Objectives:
1.
Major system characteristics of a wide range of available in-room imaging systems for IGRT.
2.
Advantages / disadvantages of different systems for site-specific IGRT considerations.
3.
Concepts of targeting accuracy and time efficiency in designing clinical imaging protocols.
Purpose: RapidArc is a more complicated technique than fixed field IMRT both in terms of treatment planning and delivery. Due to its speedy delivery, RapidArc (RA) is becoming popular in the clinics. ...Previous work has shown that the detectors used to perform patient specific IMRT QA cannot detect MLC leaf position error induced dosimetric differences even large as 5.6%. We present a patient specific QA technique with the ability to detect MLC leaf error induced dosimetric errors as small as 0.5%. Methods: Dual arc RA plans were made for treatment of head and neck, gastrointestinal and spine cancers of 10 patients on a Trilogy unit. For each patient, four plans were created: i) clinically acceptable RA plan ii) RA plan with a single MLC leaf shifted for only three consecutive control points iii) delivered original plan recreated using linac log file measurements iv) delivered shifted plan recreated using linac log file measurements. Delivered plans were recreated using only MLC positional errors from linac log file measurements. The results were analyzed by comparing voxel by voxel 3D dose differences. To quantify the actual dose difference errors due to intentional MLC shifts, a comparison was performed between the shifted dose map and the original dose map. Results: Simulated MLC shifts gave rise to a trajectory of dose differences with maximum percentage dose differences mean (range) of 0.52 (0.31 – 0.80)%, while measurements from linac log files show a maximum percentage dose differences mean (range) of 0.56 (0.31 – 0.81)%. Maximum background percentage dose differences mean (range) were 0.19 (0.05 – 0.35)%. Measurement related 3D dose map had an average signal to noise ratio of 3.89 for the set of patients analyzed. Conclusion: Linac log file measurements provide the means to detect MLC shift induced dosimetric deviations as small as 0.5% from the prescription dose. UVA Radiation Oncology George Amarino Grants ‐ 2011
Multi‐imaging modalities has afforded tremendous treatment planning opportunities to better define and delineate tumor volumes, and effectively apply highly conformal targeted therapy techniques such ...as IMRT and SBRT. With 4D CT imaging providing motion specifc information, PET yielding tumor molecular physiologic imaging, and MRI enhanced soft tissue diffentiation, these multi‐imaging modalities can introduce a comprehensive image of the planned target volumes. However, each of these technological innovations come with limitations specific to each image acquisition modality, and importing these various imaging studies into the planning system requires the employment of image registration tools, and in some case non‐rigid, deformation image registration, in order to successfully delineate tumor and target volumes for planning. This session will present strategies for management of tumor delineation using multi imaging modalities safely and effectively, including an overview of the benefits and pitfalls of tumor volume delineation using 4D CT, PET, MRI, and the various tools of deformation image registration.
Purpose: Delivering highly modulated radiation beams accurately to a moving tumor is a difficult task; it is crucial to have tools to evaluate the efficacy of treatment delivery in such cases. We are ...reporting a novel technique to evaluate 4D dose delivery to moving tumors. We are also presenting an evaluation of RapidArc treatment delivery using this method. 4D position dependant dose is crucial because the peripheral regions of the tumor may not get adequate dose due to moving out of the MLC aperture. In our procedure we accomplish the position dependant dose evaluation by creating the effects of tumor motion as follows: instead of moving the tumor, we simulate to move the active MLCs in the direction opposite to tumor motion by the corresponding motion amplitude calculated at the time of delivery. Methods: Ten RapidArc plans were created, delivered at a Varian Trilogy unit and corresponding log files were recorded. A simulation, written in MATLAB, reads in the dynalog files, and calculates average time per each control point delivery with respect to beam initiation. A sinusoidal respiratory motion signal with a given maximum amplitude and period was implemented to obtain the motion amplitude at the time of delivery of each control point. A modified DICOM file was created where the active MLCs were moved to simulate the effects of tumor motion. This DICOM plan was reimported to Eclipse treatment planning system, and 4D dose was recalculated. To verify the accuracy of our simulation, a sample plan with 2.5cm motion amplitude was compared with delivery. Results: Simulation agrees well with the dose measurement (3% /3mm gamma acceptance of 98%). GTV under‐dosing is observed for large motion amplitudes, and small tumor volumes. Conclusion: A novel technique is developed to obtain delivered 4D dose distributions for moving tumors using machine log files.
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