Opportunities for performance optimization of applications through code generation

This thesis presents the new approaches to improve the performance of a weather forecast model. These approaches require the code complexities, which can be resolved by code generation. In Chapter 2 we investigated the extension to the code generation tool CTADEL to generate code for Galerkin finite element methods. Applying to generate code for the Shallow-Water equations, we found that the generated code is 3 and 1.2 times faster than the handwritten code with the gfortran 4.1.2 and pathscale 3.0 compiler, respectively. In Chapter 3, we optimized the parallel implementation of the HIRLAM weather forecast model by overlapping communications with calculations. We found that the performance of this parallel implementation can be significantly improved by overlapping communications with calculations. In Chapter 4 we extended CTADEL to generate parallel programs. By applying this technique we have successfully generated efficient parallel code for the Shallow-Water equations. In Chapter 5 we investigated a method to speed up the HIRLAM weather forecast model. We accelerated the dynamics routine by porting it on GPUs. We found that using GPUs for weather forecasting yields an order of magnitude performance improvement over the use of conventional CPUs. In Chapter 6 we showed our extension to CTADEL to automatically generate high efficient CUDA codes. Then, we applied to generate CUDA stream code for the dynamics routine of the HIRLAM weather forecast model. The results showed that the generated code is more efficient than the optimized handwritten program.NWOUBL - phd migration 201

Improving wheelset stability of railway vehicles by using an H∞/LPV active wheelset system

The complexity of railway vehicle structures has been part of an evolutionary process for almost two hundred years. Challenges such as increased weight, increased maintenance, higher costs and energy consumption have become common. The vision for future railway vehicles is to reduce complexity, hence enable simpler structures and reduce maintenance and cost, and of course various research challenges arise from this. In fact, a number of papers in the railway engineering literature have presented practical ways to control steering of railway vehicles to improve performance. The model of the railway wheelset is highly nonlinear, mainly due to the nature of the wheelset structure and the related wheel-rail contact forces involved during operation. In this paper, the simplest design in terms of retrofitting, the actuated solid-axle wheelset is considered, we investigate actively controlled wheelsets from a Linear Parameter Varying (LPV) control aspect. We use the grid-based LPV approach to synthesize the H∞/LPV controller, which is self-scheduled by the forward velocity, as well as the longitudinal and lateral creep coefficients. The aim of the controller is to reduce the lateral displacement and yaw angle of the wheelset. Simulation results show that the proposed controller ensures the achievement of the above targets in the considered frequency domain up to 100 rad/s. © 2021 Budapest University of Technology and Economics. All rights reserved

Designing LQR controllers for an active anti-roll bar system with a flexible frame model of a single unit heavy vehicle

Rollover accidents of heavy vehicles often cause serious consequences both in terms of vehicle and environmental damage as well the loss or injury of drivers, passengers and ordinary civilians. Currently, the active anti-roll bar system is considered as the most effective solution in enhancing vehicle roll stability. In this paper, we firstly investigated the role of a flexible frame of a single unit heavy vehicle in the rollover process. This approach is an important step forward in the research of the active anti-roll bar system. Then, the LQR control method is applied in designing controllers for the active anti-roll bar control system with this frame model. The active torque of the anti-roll bar system is considered as the control signal. The simulation results in the frequency and time domains with a double lane change maneuver show that the vehicle's roll stability is improved by over 30 % compared to a vehicle using a passive anti-roll bar system. © 2021 Budapest University of Technology and Economics. All rights reserved

Opportunities for performance optimization of applications through code generation

This thesis presents the new approaches to improve the performance of a weather forecast model. These approaches require the code complexities, which can be resolved by code generation. In Chapter 2 we investigated the extension to the code generation tool CTADEL to generate code for Galerkin finite element methods. Applying to generate code for the Shallow-Water equations, we found that the generated code is 3 and 1.2 times faster than the handwritten code with the gfortran 4.1.2 and pathscale 3.0 compiler, respectively. In Chapter 3, we optimized the parallel implementation of the HIRLAM weather forecast model by overlapping communications with calculations. We found that the performance of this parallel implementation can be significantly improved by overlapping communications with calculations. In Chapter 4 we extended CTADEL to generate parallel programs. By applying this technique we have successfully generated efficient parallel code for the Shallow-Water equations. In Chapter 5 we investigated a method to speed up the HIRLAM weather forecast model. We accelerated the dynamics routine by porting it on GPUs. We found that using GPUs for weather forecasting yields an order of magnitude performance improvement over the use of conventional CPUs. In Chapter 6 we showed our extension to CTADEL to automatically generate high efficient CUDA codes. Then, we applied to generate CUDA stream code for the dynamics routine of the HIRLAM weather forecast model. The results showed that the generated code is more efficient than the optimized handwritten program

Surface Saturation with Carbon Using Plasma Arc and Graphite Coating

This study presents the development of a novel equipment for carburizing, by means of a plasma arc and a graphite paste based on liquid glass. After processing by this method, the microstructure and microhardness of the hardened layer were studied. The assay revealed that during a brief plasma exposure, the surface layer was saturated with carbon to a concentration level, which corresponds to white cast iron. The microstructures and characteristics of the metal surface post plasma cementation were also studied. The main parameters of the cemented layer were determined: the depth of the cemented layer was 150-200 µm, microhardness was up to 1000 HV0.2

Commune-level institutional arrangements and monitoring framework for integrated tree-based landscape management

Governance is a difficult task in the context of achieving landscape multifunctionality owing to the multiplicity of stakeholders, institutions, scale and ecosystem services: the ‘many-multiple’ (Cockburn et al 2018). Governing and managing the physical landscape and the actors in the landscape requires intensive knowledge and good planning systems. Land-use planning is a powerful instrument in landscape governance because it directly guides how actors will intervene in the physical landscape (land use) to gain commonly desired value. It is essential for sustaining rural landscapes and improving the livelihoods of rural communities (Bourgoin and Castella 2011, Bourgoin et al 2012, Rydin 1998), ensuring landscape multifunctionality (Nelson et al 2009, Reyers et al 2012) and enhancing efficiency in carbon sequestration, in particular (Bourgoin et al 2013, Cathcart et al 2007). It is also considered critical to the successful implementation of land-based climate mitigation, such as under Nationally Determined Contributions (NDCs), because the Land Use, Land-Use Change and Forestry (LULUCF) sector is included in the mitigation contributions of nearly 90 percent of countries in Sub-Saharan and Southern Asia countries and in the Latin American and Caribbean regions (FAO 2016)

Heat conduction and thermal conductivity of 3D cracked media

International audienceThis study deals with the heat conduction within a medium containing cracks that are assumed to be perfect insulators. Multi-region boundary element approach is employed to obtain a boundary singular integral equation governing the steady state thermal transfer within this medium. This equation presents the temperature field within the whole cracked body as a function of temperature and rate of heat flow on the domain's boundary and temperature discontinuity across the cracks. For the particular case of an infinite domain under far-field condition, the temperature field solution is only a function of the cracks tem-perature's discontinuity. The basic problem of a single crack in an infinite domain is investigated and a closed-form solution is derived for a crack of elliptic plane from this analysis. This solution is the key issue to estimate the effective thermal conductivity of the whole domain by coupling with the classical homogenization schemes. The arbitrary crack form is covered up by using the excluded volume definition. Estimations of effective thermal conductivities stemming from diluted, differential and self-consistent approaches are compared to numerical solution obtained by the finite volume modeling that is available in literature. This comparison shows that the self-consistent scheme is the most appropriate model to estimate the thermal conductivity of materials containing cracks

THE EXTRACURRICULAR CLASSES ORGANIZED THROUGH VOLUNTARY WORKS IN THE MOUNTAINOUS REGIONS FOR THE MEDIA STUDENT

The author of the present paper studies the scale and the outcomes of organizing the extracurricular classes through voluntary works in the mountain areas by evaluating the survey of participants' notion. This paper has 3 important categories: this article takes the reasons of choosing Vietnam's mountainous regions are in accord with voluntary activities into consideration, indicating the tasks and the process of carrying out extracurricular classes for students at faculty of the Multimedia Communication in Thang Long University. This paper aims to display an extracurricular learning model which is possible to carry out regularly for students in journalism and media in general. The purposes of this research do not only benefit the students but also the professor, lecturer and the whole educator because the significance of this work is that: the first is to engage students in their majors then helps them to apply their learned skills in practice, as well as contributes to renewing the traditional education at Vietnamese Universities