Modelling of Simultaneous Transformations in Steels

The microstructure of a steel is often developed by solid-state transformation from austenite. The major transformation products are allotriomorphic ferrite, pearlite, Widmanstatten ferrite, bainite and martensite, differentiated by morphological features, and their nucleation and growth mechanisms. A steel often consists of several phases as a result of dynamic evolution during continuous cooling. The complexity of the calculation of all the transformations simultaneously poses a challenge. There have been a few attempts at integrating all these transformations into an unified scheme. They involve varying degrees of empiricism. For the first time, a model that can predict simultaneously the volume proportions of all the major transformation products has been developed. The algorithm has taken full account of the thermodynamics and kinetics of individual transformations, instead of empirical equations, so the model should in principle generalise well. The predictions of the model are based on a number of input parameters: the chemical composition, austenite grain size and cooling conditions. The model can simulate cooling at constant rates, or isothermal transformations. Therefore it can also generate continuous cooling transformation (CCT), or time-temperature transformation (TTT) diagrams. The model has demonstrated a consistency in its predictions. The validations of the model against published experiment data and experiments conducted in this work have shown the predictions in most cases are reasonable with errors less than a few volume percent. Further research opportunities presented by the work are reviewed.This work was sponsored by Cambridge Overseas Trust and Swiss Steel AG

Wireless Software Synchronization of Multiple Distributed Cameras

We present a method for precisely time-synchronizing the capture of image sequences from a collection of smartphone cameras connected over WiFi. Our method is entirely software-based, has only modest hardware requirements, and achieves an accuracy of less than 250 microseconds on unmodified commodity hardware. It does not use image content and synchronizes cameras prior to capture. The algorithm operates in two stages. In the first stage, we designate one device as the leader and synchronize each client device's clock to it by estimating network delay. Once clocks are synchronized, the second stage initiates continuous image streaming, estimates the relative phase of image timestamps between each client and the leader, and shifts the streams into alignment. We quantitatively validate our results on a multi-camera rig imaging a high-precision LED array and qualitatively demonstrate significant improvements to multi-view stereo depth estimation and stitching of dynamic scenes. We release as open source 'libsoftwaresync', an Android implementation of our system, to inspire new types of collective capture applications.Comment: Main: 9 pages, 10 figures. Supplemental: 3 pages, 5 figure

Efficient data structures for piecewise-smooth video processing

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 95-102).A number of useful image and video processing techniques, ranging from low level operations such as denoising and detail enhancement to higher level methods such as object manipulation and special effects, rely on piecewise-smooth functions computed from the input data. In this thesis, we present two computationally efficient data structures for representing piecewise-smooth visual information and demonstrate how they can dramatically simplify and accelerate a variety of video processing algorithms. We start by introducing the bilateral grid, an image representation that explicitly accounts for intensity edges. By interpreting brightness values as Euclidean coordinates, the bilateral grid enables simple expressions for edge-aware filters. Smooth functions defined on the bilateral grid are piecewise-smooth in image space. Within this framework, we derive efficient reinterpretations of a number of edge-aware filters commonly used in computational photography as operations on the bilateral grid, including the bilateral filter, edgeaware scattered data interpolation, and local histogram equalization. We also show how these techniques can be easily parallelized onto modern graphics hardware for real-time processing of high definition video. The second data structure we introduce is the video mesh, designed as a flexible central data structure for general-purpose video editing. It represents objects in a video sequence as 2.5D "paper cutouts" and allows interactive editing of moving objects and modeling of depth, which enables 3D effects and post-exposure camera control. In our representation, we assume that motion and depth are piecewise-smooth, and encode them sparsely as a set of points tracked over time. The video mesh is a triangulation over this point set and per-pixel information is obtained by interpolation. To handle occlusions and detailed object boundaries, we rely on the user to rotoscope the scene at a sparse set of frames using spline curves. We introduce an algorithm to robustly and automatically cut the mesh into local layers with proper occlusion topology, and propagate the splines to the remaining frames. Object boundaries are refined with per-pixel alpha mattes. At its core, the video mesh is a collection of texture-mapped triangles, which we can edit and render interactively using graphics hardware. We demonstrate the effectiveness of our representation with special effects such as 3D viewpoint changes, object insertion, depthof- field manipulation, and 2D to 3D video conversion.by Jiawen Chen.Ph.D

Load-balanced rendering on a general-purpose tiled architecture

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.Includes bibliographical references (p. 77-80).Commodity graphics hardware has become increasingly programmable over the last few years, but has been limited to a fixed resource allocation. These architectures handle some workloads well, others poorly; load-balancing to maximize graphics hardware performance has become a critical issue. I have designed a system that solves the load-balancing problem in real-time graphics by using compile-time resource allocation on general-purpose hardware. I implemented a flexible graphics pipeline on Raw, a tile-based multicore processor. The complete graphics pipeline is expressed using StreamIt, a high-level language based on the stream programming model. The StreamIt compiler automatically maps the stream computation onto the Raw architecture. The system is evaluated by comparing the performance of the flexible pipeline with a fixed allocation representative of commodity hardware on common rendering tasks. The benchmarks place workloads on different parts of the pipeline to determine the effectiveness of the load-balance. The flexible pipeline achieves up to twice the throughput of a static allocation.by Jiawen Chen.M.Eng

Burst Denoising with Kernel Prediction Networks

We present a technique for jointly denoising bursts of images taken from a handheld camera. In particular, we propose a convolutional neural network architecture for predicting spatially varying kernels that can both align and denoise frames, a synthetic data generation approach based on a realistic noise formation model, and an optimization guided by an annealed loss function to avoid undesirable local minima. Our model matches or outperforms the state-of-the-art across a wide range of noise levels on both real and synthetic data.Comment: To appear in CVPR 2018 (spotlight). Project page: http://people.eecs.berkeley.edu/~bmild/kpn

The Contribution and Prospect of 5G Technology to China's Economic Development

Since the birth of 5G, it has attracted much attention from all countries in the world. The development of 5G industry is particularly important for domestic economic development. 4G changes life, 5G changes society. 5G will not only accelerate the speed of people surfing the Internet, but also bring revolutionary changes to all aspects of social life, making people's lives, work and entertainment more convenient and diverse. The economic impact of the development of the 5G industry on China cannot be underestimated. Nowadays, information and communication technology has increasingly become a new driving force for economic development. 5G technology has already become a key technology pursuit for countries to compete for the status of world power, and it has also become an indispensable part of contemporary economic and social development. We should give full play to the government's guiding role, and work with network giants to build a new platform for cooperation, promote coordinated industrial development, achieve win-win results, and promote economic and social prosperity and development

Axis-symmetric Onsager Clustered States of Point Vortices in a Bounded Domain

We study axis-symmetric Onsager clustered states of a neutral point vortex system confined to a two-dimensional disc. Our analysis is based on the mean field of bounded point vortices in the microcanonical ensemble. The clustered vortex states are specified by the inverse temperature $\beta$ and the rotation frequency $\omega$, which are the conjugate variables of energy $E$ and angular momentum $L$. The formation of the axis-symmetric clustered vortex states (azimuthal angle independent) involves the separating of vortices with opposite circulation and the clustering of vortices with same circulation around origin and edge. The state preserves $\rm SO(2)$ symmetry and breaks $\mathbb Z_2$ symmetry. We find that, near the uniform state, the rotation free state ($\omega=0$) emerges at particular values of $L^2/E$ and $\beta$. At large energies, we obtain asymptotically exact vortex density distributions, whose validity condition gives rise the lower bound of $\beta$ for the rotation free states. Noticeably, the obtained vortex density distribution near the edge at large energies provides a novel exact vortex density distribution for the corresponding chiral vortex system.Comment: 6 pages, 4 figure

Design, Synthesis, and Isomerization Studies of Light-Driven Molecular Motors for Single Molecular Imaging

The design of a multicomponent system that aims at the direct visualization of a synthetic rotary motor at the single molecule level on surfaces is presented. The synthesis of two functional motors enabling photochemical rotation and fluorescent detection is described. The light-driven molecular motor is found to operate in the presence of a fluorescent tag if a rigid long rod (32 angstrom) is installed between both photoactive moieties. The photochemical isomerization and subsequent thermal helix inversion steps are confirmed by H-1 NMR and UV-vis absorption spectroscopies. In addition, the tetra-acid functioned motor can be successfully grafted onto amine-coated quartz and it is shown that the light responsive rotary motion on surfaces is preserved