A great challange in robotics is to make robots more like humans. One important aspect is to make robots move like humans and recognize their motions. Both tasks are based on human motion trajectories and require a proper modelling. To accomplish these tasks, we acquire data from complex motions like setting the table, pouring water into a cup, or stirring the content of the cup. The objectives of our studies are to identify the subject doing the motion and to detect slight changes in motion constraints with automatic classification methods. For that purpose, we present reliable methods based on Elman networks and hidden Markov models. We develop the model parameters and compare the performance of the methods, especially, the classification results and the suitability for the classification tasks.

Vertebra segmentation from CT volume data is needed for several medical applications. For this, an important preprocessing step is the separation of neighboring vertebrae. We introduce a method to compute planes separating the individual vertebrae of the spine. For that purpose, a virtual balloon is inflated within the vertebral canal. After inflation, the balloon graphically shows swellings at the intervertebral regions and necks in the vertebra regions which can be distinguished by Gaussian curvature analysis on the balloon surface. Planes are constructed in the intervertebral regions separating the individual vertebrae. First tests have shown that our methods can be adapted to vertebra separation even in MRT volume data.

We construct maximum distance separable quantum error-correcting codes. The codes are defined over q-dimensional quantum systems, where q is any prime power. The construction yields quantum MDS codes of length up to q+1 for all possible dimensions and some quantum MDS codes of length up to q2+1. In particular, those families contain codes [[6,2,3]]pand [[7,3,3]]pfor pges3 (cf. [K. Feng (2002)])

The statistical state of any (classical or quantum) system with nontrivial time evolution can be interpreted as the pointer of a clock. The quality of such a clock is given by the statistical distinguishability of its states at different times. If a clock is used as a resource for producing another one the latter can at most have the quality of the resource. We show that this principle, formalized by a quasi-order, implies constraints on many physical processes. Similarly, the degree to which two (quantum or classical) clocks are synchronized can be formalized by a quasi-order of synchronism. Copying timing information is restricted by quantum no-cloning and no-broadcasting theorems since classical clocks can only exist in the limit of infinite energy. We show this quantitatively by comparing the Fisher timing information of two output systems to the input's timing information. For classical signal processing in the quantum regime our results imply that a signal looses its localization in time if it is amplified and distributed to many devices.

Summary form only given, as follows. Gives a system theoretic approach to the concept of quantum computing. A quantum computer is envisaged to be a system of quantum circuits, acting on a state space, which is a finite-say 2/sup n/-dimensional-complex Hilbert space. The circuitry is a sequence of unitary transforms U/sub t/ /spl epsiv/ SU(2/sup n/) followed by a measurement. These transforms, so-called quantum gates, are controlled by a classical computer, usually especially electromagnetic fields. The state space of a quantum computer has the structure of a Hermitian vector space. Thus it allows "simultaneous" superposition of orthogonal basis states (corresponding to classical states) with the possibility of constructive and destructive interference between different paths of computation. This principle allows the usage of so-called entangled states by preparing the superposition of special "bent" configurations of basis vectors in the product Hilbert space, e.g., as they are known from error control and cryptography. This latter "entanglement" not only promises to make a quantum computer much more powerful than a probabilistic one, but it also allows a method of parallelism. The reason for this lies not only in the fact that the 2/sup n/ dimensional Hilbert space is the n-fold tensor product of 2-dimensional spaces as it is given by spin-1/2-particles, like photons, representing a quantum bit. First of all, we shall address the fact that the power of quantum computing lies in the properties of entangled states as opposed to those of separable states which essentially would resemble classical circuits without giving the feature of exponential speed-up. We shall briefly describe possible physical realisations of quantum (optic, electronic, magnetic,...) devices allowing the engineering of Hamiltonians needed for quantum systems. Basic quantum gates, especially the quantum Horner-Toffoli gate will be discussed to display the principles and methodology for designing quantum circuits. An outlook towards the possible availability of nano- and mesoscopic technologies supporting this new architecture in future generations concludes based on a speculative worst/best case forecast of possible applications, e.g., in public key and conventional cryptography.

Usually spectra (weight distributions) of primitive binary BCH codes are supposed to approximate binomial weight distributions well for a wide range of code rates and code lengths. It is shown that for any fixed code rate R<1 spectra of long (N/spl rarr//spl infin/) primitive binary BCH codes cannot approximate the binomial distribution at all.

The problem of decomposing a single permutation into a conjugated tensor product of smaller permutations is solved.Iu general, the decomposition is not uniquely determined.An algorithm is presented which enumerates all solutions.In particular, it is possible to decide considerably fast if a permutation is tensor-indecomposable. ANNEXSTEIN, F., AND BAUMSLAG, M.A unified approach to off-line permutation routing on parallel networks.

Escrowed Key Cryptosystems hold the promise of faithfully realizing legal guarantees of privacy for users under normal circumstances while at the same time insuring that privacy can be breached by authorities in special circumstances under appropriate legal safeguards. The most attractive feature of these schemes is that it is possible to ensure that the interests of each of the parties—the users, the law enforcement or national security agencies, the court or other monitoring entities and the escrow agents—can all be guaranteed up to the level of integrity of the protocol or cryptosystem. Unfortunately, the first scheme to attempt this, the Clipper protocol as adopted by the U.S., completely fails to do so for either the user(s) or for the monitoring entities. In this paper a new escrowed key protocol and new devices are described that verifiable protect the interests of all parties by positively implementing legal guarantees of privacy and access.

Several verifiable secret sharing schemes for threshold schemes based on polynomial interpolation have been presented in the literature. Simmons and others introduced secret sharing (also called shared control) schemes based on finite geometries, which allow istributing a secret according to any monotone access structure.

The notion of trust is fundamental in inter-domain authentication protocols. The goal is to develop an effective formalism for explicit expressions of trust relations between entities involved in authentication protocols. Different relevant types of trust are identified and classified. A formalism for expressing trust relations is presented along with an algorithm for deriving trust relations from recommendations. The advantages of the approach are demonstrated by analyzing and comparing the trust relation requirements of a few known authentication protocols.>

Secure identification is an important security issue to avoid computer fraud due to masquerading. This can be achieved with zero-knowledge based smart cards. We present very efficient new zero-knowledge schemes in a general algebraic setting. Particular cases of our scheme improve the performance of the Guillou–Quisquater and the Chaum–Evertse–van de Graaf schemes. Our scheme is formally proven and, overall, is more efficient than currently available schemes including the Fiat–Shamir scheme. As an application we discuss how our scheme can be used for identification, in particular as an electronic passport scheme.

An algorithm to generate low complexity normal bases in finite fields is presented.This algorithm generalizes the method of Ash et al. to fields of arbitrary characteristic.It can be applied to most finite fields and produces (under certain conditions) the multiplication matrix for the normal basis multiplication of GF'(qn) : GI'(q) in 0(n2 log2 n log q) bit-operations.

Methods of implementing public key algorithms based on modular integer arithmetic (RSA) and finite-field arithmetic (Diffie-Hellman, El Gamal) are examined. Architectures for VLSI implementations are emphasized.>