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Introduction: Radiotherapy is one of the important treatment modalities in cancer treatment. To maintain the treatment procedure accuracy, the phantom is an essential tool for absolute dosimetry conformation and Quality Assurance routine cheek up. This work aims to study the absorbed dose of various phantoms and hence to make a comparison of the result with the IAEA recommendation (TRS 398) for daily QA of Linac. Materials and Methods: The experiment has been done at the Institute of Nuclear Medical Physics (INMP), AERE, Savar, Dhaka, under the Bangladesh Atomic Energy Commission. For external beam radiation, 6 MV and 15 MV photon beams of Varian Clinac iX Linear Accelerator (Linac) were used. One dimensional (1D) water phantom, solid water phantom, and MatriXX with MULTICube phantom and associate accessories were used to experiment. Results: We have measured and compared the absorbed dose data of the phantoms. The variation of sold water phantom from the 1D water phantom is +2.8% at 6 MV and +3.5% at 15 MV. The variation MatriXX with MULTIcube phantom from the 1D water phantom is +8.0% at 6 MV and +3.2% at 15 MV. This study revealed that the 1D water phantom was the best absolute dose conformation among the other phantoms and the deviation was within the acceptable limit (±5%), except MatriXX with MULTICube Phantom for low energy beam (8%). Conclusion: It was observed that the accuracy of dose estimation was better in the 1D water phantom rather than the other two. It is also known that the 1D water phantom is low cost but needs a long time to set up for the experimental arrangement. Solid water or MatriXX with MULTICube phantom can be used to overcome this problem, which takes only a few minutes for setup and is comparatively faster than 1D water phantom.

We describe a novel type of retroreflector, which we call a “multicube” retroreflector, optimized to provide improved optical power return when a large number of retroreflectors are dispersed through a volume or on a surface. While it does not match the performance of a “multiplane cross” type retroreflector on an individual level, it offers improved performance compared to a standard corner cube while retaining the corner cube’s advantages: fabrication via stamping, and the ability to densely pack the retroreflectors. When dispersed as part of a cloud of retroreflectors, the multicube design provides significant performance improvements over both simple corner cubes and “multiplane cross” retroreflectors.

Editor's note :As embedded systems grow more complex and as new applications such as IoT require many design constraints, sophisticated design space exploration techniques are essential in order to find the best compromise between different design goals and their tradeoff. This tutorial gives a structured insight into the field of design space exploration for embedded systems.

To meet the ever shrinking time-to-market for multimedia embedded systems, designers need effective system-level optimization techniques to support their design decisions. Despite multimedia embedded systems' highly variable execution times and soft real-time constraints, most previous work has adopted a constant execution time (worst-case) approach to evaluate if a candidate architecture satisfies the timing constraints. Such an approach is too pessimistic and might result in unnecessary costly architectures. In this work, we propose a new method for design space exploration of multimedia embedded systems. Given a system specification, the proposed method automatically explores the design space to quickly identify Pareto-optimal solutions (or an approximation) that optimize conflicting design metrics, such as price and power consumption. Our approach combines (i) a fast and formal strategy for performance evaluation that captures the varying runtime behavior of multimedia systems and (ii) a new multi-objective genetic algorithm for architecture exploration. The experiments on well-known benchmarks show the efficiency of our method in comparison to similar ones.

In this paper we outline Design Space Exploration methodology aimed at homogeneous multi-core architectures, where the safety-criticality is the crux of a system design. Multi-core architectures provide better computational abilities, but at the same time complicate the computation of timing bounds. Determining suitable architectures that achieve timing requirements is an important aspect for a system designer. The proposed work conceptualizes ways to automate and explore different design facets of a multi-core processor. The intention is to ensure that the particular application meets its deadlines, while optimizing other objectives such as minimizing hardware costs, energy consumption and floor area. The automated exploration builds upon Mulitcore Response Time Analysis for timing verification and multicube for heuristic search methods. The aim is to generate an architecture design in the end that can be used directly to build a custom application specific processor.

The previous chapter concentrated on the design of the fault detection and diagnosis system based on SCC and ANN respectively; based on the extracted features described in Chap. 6. In this chapter the implementation of the proposed robot health monitoring system using an embedded system is discussed. A short overview of the currently available embedded systems for condition monitoring applications is provided, to evaluate their appropriateness for the work here. Then, a systematic methodology has been followed for the electronic hardware, which makes up the embedded monitoring system, selection process by investigating the available options in the market and suitability for this project. The configuration of several parameters of the developed embedded system is discussed and results presented, and the final system enclosure and installation described.

Aim To study the sensitivity of three commercial dosimetric systems, Delta4, Multicube and Octavius4D, in detecting Volumetric Modulated Arc Therapy (VMAT) delivery errors. Methods Fourteen prostate and head and neck (H&N) VMAT plans were considered for this study. Three types of errors were introduced into the original plans: gantry angle independent and dependent MLC errors, and gantry angle dependent dose errors. The dose matrix measured by each detector system for the no-error and error introduced delivery were compared with the reference Treatment Planning System (TPS) calculated dose matrix for no-error plans using gamma (γ) analysis with 2%/2 mm tolerance criteria. The ability of the detector system in identifying the minimum error in each scenario was assessed by analysing the gamma pass rates of no error delivery and error delivery using a Wilcoxon signed-rank test. The relative sensitivity of the system was assessed by determining the slope of the gamma pass line for studied error magnitude in each error scenario. Results In the gantry angle independent and dependent MLC error scenario the Delta4, Multicube and Octavius4D systems detected a minimum 2 mm error. In the gantry angle dependent dose error scenario all studied systems detected a minimum 3% and 2% error in prostate and H&N plans respectively. In the studied detector systems Multicube showed relatively less sensitivity to the errors in the majority of error scenarios. Conclusion The studied systems identified the same magnitude of minimum errors in all considered error scenarios.

Reference metrics are used to define the differential structure on multicube representations of manifolds, i.e., they provide a simple and practical way to define what it means globally for tensor fields and their derivatives to be continuous. This paper introduces a general procedure for constructing reference metrics automatically on multicube representations of manifolds with arbitrary topologies. The method is tested here by constructing reference metrics for compact, orientable two-dimensional manifolds with genera between zero and five. These metrics are shown to satisfy the Gauss-Bonnet identity numerically to the level of truncation error (which converges toward zero as the numerical resolution is increased). These reference metrics can be made smoother and more uniform by evolving them with Ricci flow. This smoothing procedure is tested on the two-dimensional reference metrics constructed here. These smoothing evolutions (using volume-normalized Ricci flow with DeTurck gauge fixing) are all shown to produce reference metrics with constant scalar curvatures (at the level of numerical truncation error)., Comment: 37 pages, 16 figures; additional introductory material added in version accepted for publication

11 pp; International audience; This article deals with real-time embedded system design and verification. Real-time embedded systems are frequentlydesigned according to multi-tasking architectures that have timing constraints to meet. The design of real-time embeddedsystems expressed as a set of tasks raises a major challenge since designers have to decide how functions of the system mustbe assigned to tasks. Assigning each function to a different task will result in a high number of tasks, and then in higherpreemption overhead. In contrast, mapping many functions on a limited number of tasks leads to a less flexible design whichis more expensive to change when the functions of the system evolve. This article presents a method based on an optimizationtechnique to investigate the assignment of functions to tasks. We propose a multi-objective evolution strategy formulation whichboth minimizes the number of preemptions and maximizes task laxities. Our method allows designers to explore the search spaceof all possible function to task assignments and to find good tradeoffs between the two optimization objectives among schedulablesolutions. After explaining our mapping approach, we present a set of experiments which demonstrates its effectiveness fordifferent system sizes.

The presented Ph.D. work deals with the development of a framework to support the design of embedded systems. In particular, it focuses on the development of a unobtrusive profiling system to support, at run-time, both the definition of the best execution platform and its resource optimization. The final goal is the definition of a framework exploiting reconfigurable logic, based on monitoring actions and run-time decisions. The profiling system under development and its high portability toward different architectures, representing current status of Ph.D. work, are described. Planned future steps, including benchmarking by means of industrial applications, are illustrated.

Embedded systems are developed within a cost-driven process, such that many purpose-build systems share a common embedded platform. For instance, a shared hardware device might be applied in various use cases with different software. Here, the bare hardware is considered as platform while the final hardware/software system is the product that implements a certain set of features. In this paper, we propose an efficient design space exploration methodology that optimizes a set of embedded platforms. For this purpose, we separate the exploration into two stages: (1) A set of candidate platforms is determined within an optimization framework that can cope with different system models, considering the optimization objectives and feature coverage. (2) The final set of target platforms is determined as subset of the candidates by minimizing the expected objectives like cost, area, etc. The experimental results give evidence that our modular approach is more flexible and scalable than state-of-the-art methodologies.