Area efficient computing structures for concurrent error detection in systolic arrays

A method of designing testable systolic architectures is proposed in this paper. Testing systolic arrays involves mapping of an algorithm into a specific VLSI systolic architecture, and then modifying the design to achieve concurrent testing. In our approach, redundant computations are introduced at the algorithmic level by deriving two versions of a given algorithm. The transformed dependency matrix (TDM) of the first version is a valid transformation matrix while the second version is obtained by rotating the first TDM by 180 degrees about any of the indices that represent the spatial component of the TDM. Concurrent error detection (CED) systolic array is constructed by merging the corresponding systolic array of the two versions of the algorithm. The merging method attempts to obtain the self testing systolic array at minimal cost in terms of area and speed. It is based on rescheduling input data, rearranging data flow, and increasing the utilization of the array cells. The resulting design can detect all single permanent and temporary faults and the majority of the multiple fault patterns with high probability. The design method is applied to an algorithm for matrix multiplication in order to demonstrate the generality and novelty of our approach to design testable VLSI systolic architectures.This work has been supported by a grant from the Natural Sciences and Engineering Research Council of Canada.     

Cardiac simulation on multi-GPU platform

The cardiac bidomain model is a popular approach to study electrical behavior of tissues and simulate interactions between the cells by solving partial differential equations. The iterative and data parallel model is an ideal match for the parallel architecture of Graphic Processing Units (GPUs). In this study, we evaluate the effectiveness of architecture-specific optimizations and fine grained parallelization strategies, completely port the model to GPU, and evaluate the performance of single-GPU and multi-GPU implementations. Simulating one action potential duration (350 msec real time) for a 256×256×256 tissue takes 453 hours on a high-end general purpose processor, while it takes 664 seconds on a four-GPU based system including the communication and data transfer overhead. This drastic improvement (a factor of 2460×) will allow clinicians to extend the time-scale of simulations from milliseconds to seconds and minutes; and evaluate hypotheses in a shorter amount of time that was not feasible previously.     

Traumatic injury induces interleukin-6 production by human astrocytes

The brain is being evaluated as a de novo source of cytokines. Because recent evidence indicates that interleukin-6 (IL-6) may influence blood-brain barrier function and vascular permeability, we have sought to determine whether mechanical injury can directly induce in situ cerebral IL-6 production. Adult human astrocyte cultures were subjected to mechanical injury by the in vitro method of fluid percussion barotrauma, developed in our laboratory. Serial supernatant samples were collected for 8 h and evaluated for IL-6 activity using a proliferation assay employing the dependent B cell hybridoma cell line, B9. At optimum injury, the IL-6 level became significantly (P < 0.0001, analysis of variance) elevated from baseline 2 h after trauma and continued to increase over the observation period. Our study shows that following mechanical injury human astrocytes produce IL-6, which may contribute to post-traumatic cerebrovascular dysfunction. Elucidating the precise role of intracerebral cytokines is essential to our understanding of the mechanism responsible for post-traumatic cerebrovascular dysfunction.     

Korrosionsmonitoring und Bruchortung in Spannbetonbauwerken – Möglichkeiten und Grenzen

Corrosion Monitoring and Fracture Detection in Prestressed Concrete Structures – Possibilities and Limits Corrosive influences may affect the long‐term functionality of prestressed elements of prestressed concrete constructions and may lead to catastrophic failure of the member. Hence, the objective of the condition assessment of prestressed components has to be detecting existing defects and damages of the prestressed elements, e.g. grouting faults, corrosion and steel fractures in time. For an objectively early diagnosis of corrosion damages on prestressing elements, the Structural Health Monitoring (SHM) based on non‐destructive testing and monitoring methods is predestined. In this contribution causes of tendon corrosion in prestressed concrete (PC) bridges will first be specified, furthermore advantages and the strategy of corrosion monitoring are presented. Afterwards the state of the research and art of non‐destructive techniques and evaluation (NDT/NDE) of the corrosion state and of fracture detection of the prestressed elements in bridges with its possibilities and limits will be discussed. In this context also innovative sensors and measuring methods developed by the authors at the iBMB within the collaborative research center (CRC) 477 “Structural Health Monitoring” will be introduced.     

A note on minimising total absolute deviation of job completion times on a two-machine no-wait proportionate flowshop

A popular measure used in service systems is that of total absolute deviation of job completion times (TADC). It is relevant to settings where the objective is to balance the level of service provided to different customers. During the last decade, TADC has been studied in various machine settings, and under various assumptions on the job processing times. In this note, we study TADC on a two-machine no-wait proportionate flow shop, i.e. a flow shop with machine-independent processing times, and with no buffer between the machines. A very surprising and unique result is introduced: a simple index policy (the well-known largest processing time (LPT) first sequence) is shown to be optimal for instances of no more than seven jobs. This property does not hold for larger instances. We show that for instances of eight and nine jobs, there are exactly two schedules which are candidates for optimality. For the 10-job instance, the number of candidates increases. This uncommon behaviour of the optimal solution and, consequently, the complexity of the problem studied here, remain open questions, and are challenging topics for future research.     

Performance of Nd:YAG lasers in coupled generalized self-filtering and positive-branch unstable resonators

A new optical resonator based on the combination of a generalized self-filtering unstable resonator (GSFUR) and a positive-branch unstable resonator (PBUR) in a three-mirror scheme is reported. It is shown both theoretically and experimentally that a nearly diffraction-limited Gaussian-output laser beam with a large mode volume can be obtained with this cavity design. The laser cavity is particularly interesting for use in high-threshold pumped gain media and eliminates some disadvantages of the SFUR and GSFUR designs. This resonator, with an effective magnification of -6.16, was applied to a pulsed Nd:YAG laser in free-running and in Q-switched modes of operation. The output energy was ~70 mJ, 5.5 times greater than when a single GSFUR design was used. The output beam had a pulse duration of ~30 ns in the Q-switched mode of operation and a beam divergence of 0.26 mrad. The required relations for the GSFUR-PBUR optical design and the output energy were derived and verified experimentally.