On convergence proofs in system identification – a general principle using ideas from learning theory

It is shown that learning theory offers convergence analysis tools that are useful in system identification problems. They allow analysis in a parameter-free context, which elevates the analysis from parameter sets to model sets and from parameter identification to model identification. When a parameterization is eventually introduced, this leads to alternative assumptions on the parameterization and parameter set. Moreover, structural identification can be analyzed within the same framework. Another advantage is that the proofs are technically and conceptually simple.     

Image analysis of dermal collagen changes during skin aging

A missense mutation in the human alpha synuclein gene was recently identified in some cases of familial Parkinson's disease (FPD). We have developed an antibody that recognizes the C-terminal 12 amino acids of the human alpha synuclein protein and have demonstrated that alpha synuclein is an abundant component of the Lewy bodies found within the degenerating neurons of patients with Parkinson's disease (PD). The presence of alpha synuclein in Lewy bodies of sporadic PD patients suggests a central role for alpha synuclein in the pathogenesis of PD.     

Upper bound for a hybrid sum over Galois rings with applications toaperiodic correlation of some q-ary sequences

An upper bound for a hybrid exponential sum over Galois rings is derived. This bound is then used to obtain an upper bound for the maximum aperiodic correlation of some sequence families over Galois rings. The bound is of the order of √qlnq where q-1 is the period of the sequences     

Cyclic codes over Z4, locator polynomials, and Newton'sidentities

Certain nonlinear binary codes contain more codewords than any comparable linear code presently known. These include the Kerdock (1972) and Preparata (1968) codes that can be very simply constructed as binary images, under the Gray map, of linear codes over Z₄ that are defined by means of parity checks involving Galois rings. This paper describes how Fourier transforms on Galois rings and elementary symmetric functions can be used to derive lower bounds on the minimum distance of such codes. These methods and techniques from algebraic geometry are applied to find the exact minimum distance of a family of Z ₄. Linear codes with length 2^m (m, odd) and size 2(2^m+1-5m-2). The Gray image of the code of length 32 is the best (64, 2³⁷) code that is presently known. This paper also determines the exact minimum Lee distance of the linear codes over Z₄ that are obtained from the extended binary two- and three-error-correcting BCH codes by Hensel lifting. The Gray image of the Hensel lift of the three-error-correcting BCH code of length 32 is the best (64, 2³²) code that is presently known. This code also determines an extremal 32-dimensional even unimodular lattice     

Estimating intramuscular fat content and fatty acid composition in live and post-mortem samples in pigs

Repeated muscle sampling (n = 732) on 216 pigs was performed to evaluate the effect of live sampling and sample size on intramuscular fat (IMF) content and fatty acid (FA) composition. The sampling scheme consisted of 1–3 biopsies of longissimus dorsi (LM), a small and a big post-mortem sample of LM, and a big post-mortem sample of gluteus medius (GM). IMF was determined by quantitative gas chromatography after direct transesterification. Data on LM were jointly analyzed using a mixed model on age with heterogeneous residual variances across sampling methods. Biopsies overestimated IMF and polyunsaturated FA content and underestimated monounsaturated FA content with decreasing sample size. Potential for bias and not sampling variance is the major limitation of using live samples for assessing changes in IMF with age. Small post-mortem samples of LM were as informative as big samples of GM for inferring IMF content but not IMF composition.     

PIUS - status and perspectives

Today's environmental concerns show that nuclear energy is an important option for meeting future increases in global energy demand. Significant nuclear expansion will probably require new reactor designs in which safety is ensured by simple, convincing means. PIUS represents such a reactor design. It is a re-configured 600 MWe PWR, in which the primary safety goal, protection of the reactor core integrity, is entrusted to built-in, self-protective, passive features, without reliance on any monitoring, detection or actuation system, nor operator action. Its basic design features a core that is openly connected, in a natural circulation loop, to a large pool of borated water. The pool is enclosed in a prestressed concrete pressure vessel provided with redundant leakage barriers. The reactor coolant pumps are operated in such a way that there is hydraulic balance in the openings between the primary coolant loop and the pool. Thereby, the hot, low boron content primary loop water is kept separated from the pool water, in spite of the always open natural circulation loop. In severe transients this balance is disturbed, and pool water ingress occurs, shutting down the reactor, or restricting the power to a safe level. The decay heat is transferred to the pool by the natural circulation loop, and a passive pool cooling system, utilizing natural circulation and natural draft cooling towers, prevents boiling of the pool water, even in a station blackout situation. Transient analyses have shown that this passive long-term RHR function will be available in all accident situations, even after double-ended cold leg breaks. Such breaks result in a temporary pressurization of the reactor containment, but the releases of radioactivity will be extremely small and the doses at the fence boundary very low. Cost estimates indicate that PIUS will be quite competitive, and evaluation studies are now under way in several countries.     

On the facet-to-facet property of solutions to convex parametric quadratic programs

In some of the recently developed algorithms for convex parametric quadratic programs it is implicitly assumed that the intersection of the closures of two adjacent critical regions is a facet of both closures; this will be referred to as the facet-to-facet property. It is shown by an example, whose solution is unique, that the facet-to-facet property does not hold in general. Consequently, some existing algorithms cannot guarantee that the entire parameter space will be explored. A simple modification, applicable to several existing algorithms, is presented for the purpose of overcoming this problem. Numerical results indicate that, compared to the original algorithms for parametric quadratic programs, the proposed method has lower computational complexity for problems whose solutions consist of a large number of critical regions.     

An analog continuous-time neural network

An analog continuous-time neural network is described. Building blocks which include the capability for on-chip learning and an example network are described and test results are presented. We are using analog nonvolatile CMOS floating-gate memories for storage of the neural weights. The floating-gate memories are programmed by illuminating the entire chip with ultraviolet light. The subthreshold operation of the CMOS transistor in analog VLSI has a very low power dissipation which can be utilized to build larger computational systems, e.g., neural networks. The experimental results show that the floating-gate memories are promising, and that the building blocks are operating as separate units; however, especially the time constants involved in the computations of the continuous-time analog neural network should be studied further.