Algorithm Developments for Discrete Adjoint Methods

This paper presents a number of algorithm developments for adjoint methods using the 'discrete' approach in which the discretisation of the non-linear equations is linearised and the resulting matrix is then transposed. With a new iterative procedure for solving the adjoint equations, exact numerical equivalence is maintained between the linear and adjoint discretisations. The incorporation of strong boundary conditions within the discrete approach is discussed, as well as a new application of adjoint methods to linear unsteady flow in turbomachinery

The use of the adjoint method for the minimisation of forced vibration in turbomachinery

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Adjoint harmonic sensitivities for forced response minimization

This paper presents an adjoint analysis for three-dimensional unsteady viscous flows aimed at the calculation of linear worksum sensitivities involved in turbomachinery forced response predictions. The worksum values are normally obtained from linear harmonic flow calculations but can also be computed using the solution to the adjoint of the linear harmonic flow equations. The adjoint method has a clear advantage over the linear approach if used within a rotor forced vibration minimization procedure which requires the structural response to a large number of different flow excitation sources characterized by a unique frequency and interblade phase angle. Whereas the linear approach requires a number of linear flow calculations at least equal to the number of excitation sources, the adjoint method reduces this cost to a single adjoint solution for each structural mode of rotor response. A practical example is given to illustrate the dramatic computational saving associated with the adjoint approach

Real-Time Defects Analyses Using High-Speed Imaging during Aluminum Magnesium Alloy Laser Welding

In this study a continuous wave Ytterbium-doped Yttrium Aluminum Garnet (Yb: YAG) disk laser has been used for welding of AlMg3 casted alloy. A high-speed imaging camera has been employed to record hot vapor plume features during the process. The purpose was to identify a mechanism of pores detection in real-time based on correlations between metallographic analyses and area/intensity of the hot vapor in various locations of the samples. The pores formation and especially the position of these pores had to be kept under control in order to weld thick samples. Based on the characterization of the hot vapor, it has been found that the increase of the vapor area that exceeded a threshold value (18.5 ± 1 mm2) was a sign of pores formation within the weld seam. For identification of the pores’ locations during welding, the monitored element was the hot vapor intensity. The hot vapor core spots having a grayscale level reaching 255 was associated with the formation of a local pore. These findings have been devised based on correlation between pores placement in welds cross-section microscopy images and the hot vapor plume features in those respective positions

Real-Time Defects Analyses Using High-Speed Imaging during Aluminum Magnesium Alloy Laser Welding

In this study a continuous wave Ytterbium-doped Yttrium Aluminum Garnet (Yb: YAG) disk laser has been used for welding of AlMg3 casted alloy. A high-speed imaging camera has been employed to record hot vapor plume features during the process. The purpose was to identify a mechanism of pores detection in real-time based on correlations between metallographic analyses and area/intensity of the hot vapor in various locations of the samples. The pores formation and especially the position of these pores had to be kept under control in order to weld thick samples. Based on the characterization of the hot vapor, it has been found that the increase of the vapor area that exceeded a threshold value (18.5 ± 1 mm2) was a sign of pores formation within the weld seam. For identification of the pores’ locations during welding, the monitored element was the hot vapor intensity. The hot vapor core spots having a grayscale level reaching 255 was associated with the formation of a local pore. These findings have been devised based on correlation between pores placement in welds cross-section microscopy images and the hot vapor plume features in those respective positions

The Impact Of Introducing Virtual Slides As A Replacement For Powerpoint Presentations In The Students’ Microscopy Labs

INTRODUCTION / BACKGROUND: The medical school students in Timisoara, Romania have been studying pathology slides in microscopy labs according to a protocol which uses classical PowerrPoint presentations as guides for understanding the microscopic features of diseases, followed by individual examination of the glass slides under the microscope. AIMS: We aimed to assess the impact of replacing those presentations with virtual slides (VS). METHODS: In the middle of the semester, for the benign tumors microscopy lab, which is presented over the course of 2 weeks, we used 3 VS, while the other 3 slides were presented in the classical PowerPoint manner. All attending students from the 3rd year of the Medical School of the University of Medicine and Pharmacy “Victor Babes” Timisoara were asked to fill out an anonymous questionnaire at the end of the lab, in which they graded the difficulty in identifying lesions, chose the best/least understood lesion and pointed out the best manner of presentation. RESULTS: 431 valid questionnaires were collected. 52.9% of the students indicated one of the 3 VS as the best understood lesion, while 59.62% chose a different VS as a least understood one. One VS was also the top best (113/332 votes) while another the least understood (34/126 votes) lesion. 74.01% students agreed that VS helped them understand the microscopic criteria better, while 74.71% would like VS to be used in the labs to come. CONCLUSION: VS were appreciated by the students as a novelty and a more impressing way of studying pathology slides, but did not dramatically improve the easiness with which they identify and understand the lesions