A singular loop transformation framework based on non-singular matrices

In this paper, we discuss a loop transformation framework that is based on integer non-singular matrices. The transformations included in this framework are called Λ-transformations and include permutation, skewing and reversal, as well as a transformation calledloop scaling. This framework is more general than existing ones; however, it is also more difficult to generate code in our framework. This paper shows how integer lattice theory can be used to generate efficient code. An added advantage of our framework over existing ones is that there is a simple completion algorithm which, given a partial transformation matrix, produces a full transformation matrix that satisfies all dependences. This completion procedure has applications in parallelization and in the generation of code for NUMA machines. This work was supported by the Cornell Theory Center, NSF Presidential Young Investigator award #CCR-8958543. by NSF Grant #CCR-9008526, and by a grant from the Hewlett-Packard Company.     

Look Left, Look Right, Look Left Again: An Application of Fractal Symbolic Analysis to Linear Algebra Code Restructuring

Fractal symbolic analysis is a symbolic analysis technique for verifying the legality of program transformations. It is strictly more powerful than dependence analysis; for example, it can be used to verify the legality of blocking LU factorization with pivoting, a task for which dependence analysis is inadequate. In this paper, we show how fractal symbolic analysis can be used to convert between left- and right-looking versions of three kernels of central importance in computational science: triangular solve, Cholesky factorization, and LU factorization with pivoting.     

Silver Nanoparticles from Ultrasonic Spray Pyrolysis of Aqueous Silver Nitrate

Silver particles less than 20 nm in diameter were synthesized by pyrolysis of an ultrasonically atomized spray of highly dilute aqueous silver nitrate solution at temperatures above 650°C and below the melting point of silver. Feed solution concentration and ultrasound power applied to the atomizer were found to have a significant impact on the particle size of the silver nanoparticles. Average particle size was found to be controllable in the range of 20 nm to 300 nm by varying the solution concentration and the ultrasound power to the atomizer.     

DIRECT SYNTHESIS OF RU-NI NANOPARTICLES WITH CORE-AND-SHELL STRUCTURE

Nanoparticles of Ru-Ni with a core-and-shell structure were synthesized as potential catalysts for fuel cells and other applications in a single-step spray-pyrolysis process at 700°-800°C. The majority of the core consists of ruthenium, while the shell is predominately composed of nickel. Bimetallic nanoparticles with a core-and-shell structure are being considered as new and promising catalysts with enhanced catalytic activity, better stability, and higher resistance to contaminants for fuel cells and other applications. An aqueous precursor containing ruthenium chloride and nickel chloride was nebulized by an ultrasonic atomizer to generate an aerosol. Droplets were subsequently decomposed to form uniformly distributed Ru-Ni bimetallic nanoparticles, then deposited on a substrate. Atomic fractions and melting temperatures are expected to play a crucial role in the formation of core-and-shell structures.     

Instantly indexed multimedia databases of real world events

We introduce a new paradigm for real-time conversion of a real world event into a rich multimedia database by processing data from multiple sensors observing the event. A real-time analysis of the sensor data, tightly coupled with domain knowledge, results in instant indexing of multimedia data at capture time. This yields semantic information to answer complex queries about the content and the ability to extract portions of data that correspond to complex actions performed in the real world. The power of such an instantly indexed multimedia database system, in content-based retrieval of multimedia data or in semantic analysis and visualization of the data, far exceeds that of systems which index multimedia data only after it is produced. We present LucentVision, an instantly indexed multimedia database system developed for the sport of tennis. This system analyzes video from multiple cameras in real time and captures the activity of the players and the ball in the form of motion trajectories. The system stores these trajectories in a database along with video, 3D models of the environment, scores, and other domain-specific information. LucentVision has been used to enhance live television and Internet broadcasts with game analyses and virtual replays in more than 250 international tennis matches.     

DIRECT SYNTHESIS OF RU-NI NANOPARTICLES WITH CORE-AND-SHELL STRUCTURE

Nanoparticles of Ru-Ni with a core-and-shell structure were synthesized as potential catalysts for fuel cells and other applications in a single-step spray-pyrolysis process at 700°–800°C. The majority of the core consists of ruthenium, while the shell is predominately composed of nickel. Bimetallic nanoparticles with a core-and-shell structure are being considered as new and promising catalysts with enhanced catalytic activity, better stability, and higher resistance to contaminants for fuel cells and other applications. An aqueous precursor containing ruthenium chloride and nickel chloride was nebulized by an ultrasonic atomizer to generate an aerosol. Droplets were subsequently decomposed to form uniformly distributed Ru-Ni bimetallic nanoparticles, then deposited on a substrate. Atomic fractions and melting temperatures are expected to play a crucial role in the formation of core-and-shell structures.     

Data-Centric Transformations for Locality Enhancement

On modern computers, the performance of programs is often limited by memory latency rather than by processor cycle time. To reduce the impact of memory latency, the restructuring compiler community has developed locality-enhancing program transformations such as loop permutation and tiling. These transformations work well for perfectly nested loops (loops in which all assignment statements are contained in the innermost loop), but their performance on codes such as matrix factorizations that contain imperfectly nested loops leaves much to be desired. In this paper, we propose an alternative approach called data-centric transformation. Instead of reasoning directly about the control structure of the program, a compiler using the data-centric approach chooses an order for the arrival of data elements in the cache, determines what computations should be performed when that data arrives, and generates the appropriate code. At runtime, program execution will automatically pull data into the cache in an order that corresponds approximately to the order chosen by the compiler; since statements that touch a data structure element are scheduled close together, locality is improved. The idea of data-centric transformation is very general, and in this paper, we discuss a particular transformation called data-shackling. We have implemented shackling in the SGI MIPSPro compiler which already has a sophisticated implementation of control-centric transformations for locality enhancement. We present experimental results on the SGI Octane comparing the performance of the two approaches, and show that for dense numerical linear algebra codes, data-shackling does better by factors of two to five.     

Synthesis of Ru-Ni Core-Shell Nanoparticles for Potential Sensor Applications

Nanoparticles of Ru-Ni with a core-and-shell structure were synthesized as potential sensors in a single-step spray-pyrolysis process at 700-1000. The majority of the core consists of ruthenium, while the shell is predominately composed of nickel. An aqueous precursor containing ruthenium chloride and nickel chloride was nebulized by an ultrasonic atomizer to generate an aerosol. The aerosol droplets were subsequently decomposed to form uniformly distributed Ru-Ni bimetallic nanoparticles. Atomic fractions of precursors, solvent type and process temperature play crucial roles in the formation of core-and-shell structures.