While there have been many reported implementations of networks-on-chip (NoCs) on FPGAs, they have not seen the same acceptance as NoCs on ASICs. One reason is that communication on an FPGA is already costly due to the die resources and time delays inherent in the reconfigurable structure. Layering another general-purpose network on top of the reconfigurable network simply incurs too many performance penalties. There is, however, already a largely unused, global network available in FPGAs. As a proof-of-concept, we demonstrate that the Xilinx FPGA configuration circuitry, which is normally idle during system operation, can function as a relatively high-performance NoC. MetaWire performs transfers through an overclocked Virtex-4 internal configuration access port (ICAP) and is shown to provide a bandwidth exceeding 200 MBytes/sec.

A clear association has been demonstrated between gait stability and falls in the elderly. Integration of wearable computing and human dynamic stability measures into home automation systems may help differentiate fall-prone individuals in a residential environment. The objective of the current study was to evaluate the capability of a pair of electronic textile (e-textile) pants system to assess local dynamic stability and to differentiate motion-impaired elderly from their healthy counterparts. A pair of e-textile pants comprised of numerous e-TAGs at locations corresponding to lower extremity joints was developed to collect acceleration, angular velocity and piezoelectric data. Four motion-impaired elderly together with nine healthy individuals (both young and old) participated in treadmill walking with a motion capture system simultaneously collecting kinematic data. Local dynamic stability, characterized by maximum Lyapunov exponent, was computed based on vertical acceleration and angular velocity at lower extremity joints for the measurements from both e-textile and motion capture systems. Results indicated that the motion-impaired elderly had significantly higher maximum Lyapunov exponents (computed from vertical acceleration data) than healthy individuals at the right ankle and hip joints. In addition, maximum Lyapunov exponents assessed by the motion capture system were found to be significantly higher than those assessed by the e-textile system. Despite the difference between these measurement techniques, attaching accelerometers at the ankle and hip joints was shown to be an effective sensor configuration. It was concluded that the e-textile pants system, via dynamic stability assessment, has the potential to identify motion-impaired elderly.

Electronic textile research often centers on the concept of introducing electronics to apparel such as shirts jackets, gloves, and health vests. Another less researched concept incorporates electronics into large textile surfaces such as carpets and upholstery. In this paper we explore methods and challenges of building a large surface area electronic textile floor for cooperative mobile device interaction. We systematically construct both a 100ft by 50ft textile simulation and a 3ft by 8ft working prototype using readily available materials. We introduce the broadly applicable embedded workload of human gait tracking as a means to defining the requirements for the textile physicals, networked computing node, and distributed execution environment subsystems. Through this effort we begin to establish a working model for combining inexpensive electronic textiles with a scalable execution environment that supports mobile device to floor interactions.

This paper describes an autonomous, wearable location awareness system that determines a user's location within a building given a map of that building. The system uses a moderate number of ultrasonic range transceivers as the sensing elements. Given a set of range readings from these sensors, the system attempts to match those actual readings to expected readings associated with a set of candidate locations for the wearer. These expected readings are calculated using a simulation model of the propagation of ultrasonic signals within a building. A complementary algorithm is given for determining the wearer's movement between rooms, allowing for the uncertainty associated with sensor readings in complex, multiroom environments. A wearable prototype system is described and results from this system in a range of scenarios are presented and analyzed

This paper describes our design of a simulation environment for electronic textiles (e-textiles) and our experiences with that environment. This simulation environment, based upon Ptolemy II, enables us to model a diverse range of areas related to the design of electronic textiles, including the physical environment they will be used in, the behavior of the sensors incorporated into the fabric, the on-fabric network, the power consumption of the system, and the execution of the application and system software. This paper focuses on two aspects of the system, modeling the motion of a person wearing the e-textile and modeling the effect of faults in the e-textile system. To partially validate this environment, we compare simulation results against results from two different physical prototypes, a large-scale acoustic beamformer and a pair of shape-sensing pants.

The invention of the Jacquard weaving machine led to the concept of a stored "program" and "mechanized" binary information processing. This development served as the inspiration for C. Babbage's analytical engine-the precursor to the modern-day computer. Today, more than 200 years later, the link between textiles and computing is more realistic than ever. In this paper, we look at the synergistic relationship between textiles and computing and identify the need for their "integration" using tools provided by an emerging new field of research that combines the strengths and capabilities of electronics and textiles into one: electronic textiles, or e-textiles. E-textiles, also called smart fabrics, have not only "wearable" capabilities like any other garment, but also have local monitoring and computation, as well as wireless communication capabilities. Sensors and simple computational elements are embedded in e-textiles, as well as built into yarns, with the goal of gathering sensitive information, monitoring vital statistics, and sending them remotely (possibly over a wireless channel) for further processing. The paper provides an overview of existing efforts and associated challenges in this area, while describing possible venues and opportunities for future research.

The paper describes a plug-in for the Winamp MP3 player that uses a configurable computer to provide digital special effects for audio streams. The plug-in makes use of run-time reconfiguration, modification of FPGA configuration bitstreams at run time, and context switching. The plug-in effects processor provides filters for a graphic equalizer and an echo effect. These filters are context-switched during the runtime of an application to reduce the amount of hardware required. Further, the effects embodied in the filters are changed on-the-fly by modifying the configuration bitstreams at runtime using the JBits API. These techniques are described and results on the performance of the application are presented.

The evolution of computer networking technology will likely require hardware that is flexible enough to adapt to changing standards while maintaining the highest possible performance. Much research has recently been done in active networks, which increase network flexibility by allowing the routers to be reprogrammed, often at the cost of lower throughput. A reconfigurable router implemented on a Custom Computing Machine (CCM) can provide the flexibility required for active networking while approaching the high throughput of inflexible application-specific integrated circuit (ASIC)-based routers. This paper presents an implementation of a prototype reconfigurable router on the Wildforce platform. The prototype implements IPv4 routing with a throughput of up to 576 Mbps, using a stream-based approach that facilitates dynamic reconfiguration.

Many applications require the use of multiple, loosely-coupled adaptive computing boards as part of a larger computing system. Two such application classes are embedded systems in which multiple boards are required to physically interface to different sensors/actuators and applications whose computational demands require multiple boards. In addition to the adaptive computing boards, the computing systems for these application classes typically include general-purpose microprocessors and high-speed networks. The development environment for applications on these large computing systems is not unified. Typically, a developer uses VHDL simulation and synthesis tools to program the FPGAs on the adaptive computing boards. External control for the board, such as downloading new configurations or setting clock speeds, is provided through a vendor-specific API. This API is typically accessed in a C host program that the developer must write in a high-level language environment. Finally, the developer is responsible for writing the networking code that allows interaction between the separate adaptive computing boards and general-purpose microprocessors. No tools are available for either debugging or performance monitoring in this agglomerated system. Development on these systems is time-consuming and platform-specific. A standard ACS API is proposed to provide a developer with a single API for the control of a distributed system of adaptive computing boards, including the interconnection network.

Incomplete factorization has been shown to be a good preconditioner for the conjugate gradient method on a wide variety of problems. It is well known that allowing some fill-in during the incomplete factorization can significantly reduce the number of iterations needed for convergence. Allowing fill-in, however, increases the time for the factorization and for the triangular system solutions. Additionally, it is difficult to predict a priori how much fill-in to allow and how to allow it. The unpredictability of the required storage/work and the unknown benefits of the additional fill-in make such strategies impractical to use in many situations. In this article we motivate, and then present, two “black-box” strategies that significantly increase the effectiveness of incomplete Cholesky factorization as a preconditioner. These strategies require no parameters from the user and do not increase the cost of the triangular system solutions. Efficient implementations for these algorithms are described. These algorithms are shown to be successful for a variety of problems from the Harwell-Boeing sparse matrix collection.

Efficient and reliable code to compute incomplete Cholesky factors of sparse matrices for use as preconditioners in a conjugate gradient algorithm is described. This code implements two recently developed, improved incomplete factorization algorithms. An efficient implementation of the standard incomplete Cholesky factorization is also included.

A general-purpose parallel iterative solver for large, sparse systems of linear equations is presented. This solver is used in two applications, a piezoelectric crystal vibration problem and a superconductor model, which could be solved only on the largest available massively parallel machine. Results obtained on the Intel DELTA show computational rates of up to 3.25 Gflops for these applications.>