Storing hydrogen in the form of light alloy hydrides

Different hydrides are investigated to find a system with a sufficiently high storage density (at least 3%). The formation of hydrides with light alloys is examined. Reaction kinetics for hydride formation were defined and applied to the systems Mg-Al-H, Mg-Al-Cu-H, Ti-Al-H, Ti-Al-Cu-H, and Ti-Al-Ni-H. Results indicate that the addition of Al destabilizes MgH2 and TiH2 hydrides while having only a limited effect on the storage density

Control of intelligent robots in space

In view of space activities like International Space Station, Man-Tended-Free-Flyer (MTFF) and free flying platforms, the development of intelligent robotic systems is gaining increasing importance. The range of applications that have to be performed by robotic systems in space includes e.g., the execution of experiments in space laboratories, the service and maintenance of satellites and flying platforms, the support of automatic production processes or the assembly of large network structures. Some of these tasks will require the development of bi-armed or of multiple robotic systems including functional redundancy. For the development of robotic systems which are able to perform this variety of tasks a hierarchically structured modular concept of automation is required. This concept is characterized by high flexibility as well as by automatic specialization to the particular sequence of tasks that have to be performed. On the other hand it has to be designed such that the human operator can influence or guide the system on different levels of control supervision, and decision. This leads to requirements for the hardware and software concept which permit a range of application of the robotic systems from telemanipulation to autonomous operation. The realization of this goal requires strong efforts in the development of new methods, software and hardware concepts, and the integration into an automation concept

Generalization bounds for averaged classifiers

We study a simple learning algorithm for binary classification. Instead of predicting with the best hypothesis in the hypothesis class, that is, the hypothesis that minimizes the training error, our algorithm predicts with a weighted average of all hypotheses, weighted exponentially with respect to their training error. We show that the prediction of this algorithm is much more stable than the prediction of an algorithm that predicts with the best hypothesis. By allowing the algorithm to abstain from predicting on some examples, we show that the predictions it makes when it does not abstain are very reliable. Finally, we show that the probability that the algorithm abstains is comparable to the generalization error of the best hypothesis in the class.Comment: Published by the Institute of Mathematical Statistics (http://www.imstat.org) in the Annals of Statistics (http://www.imstat.org/aos/) at http://dx.doi.org/10.1214/00905360400000005

Equilibrium orbit analysis in a free-electron laser with a coaxial wiggler

An analysis of single-electron orbits in combined coaxial wiggler and axial guide magnetic fields is presented. Solutions of the equations of motion are developed in a form convenient for computing orbital velocity components and trajectories in the radially dependent wiggler. Simple analytical solutions are obtained in the radially-uniform-wiggler approximation and a formula for the derivative of the axial velocity $v_{\|}$ with respect to Lorentz factor $\gamma$ is derived. Results of numerical computations are presented and the characteristics of the equilibrium orbits are discussed. The third spatial harmonic of the coaxial wiggler field gives rise to group $III$ orbits which are characterized by a strong negative mass regime.Comment: 13 pages, 9 figures, to appear in phys. rev.

The Evolution of Securitization in Multifamily Mortgage markets and Its Effect on lending Rates

Loan purchase and securitization by Freddie Mac, Fannie Mae and private-label commercial mortgage-backed securities (CMBS) grew rapidly during the 1990s and accounted for more than one-half of the net growth in multifamily debt over the decade. By facilitating the integration of the multifamily mortgage market into the broader capital markets, securitization helped to create new sources of credit as some traditional portfolio investors—savings institutions and life insurers—reduced their share of loan holdings. A model of commercial mortgage rates at life insurers, expressed relative to a comparable-term Treasury yield, was estimated over a twenty-two-year period. The parameter estimates supported an option-based pricing model of rate determination; proxies for CMBS activity showed no significant effect.

Non-universality in Micro-branching Instabilities in Rapid Fracture: the Role of Material Properties

In spite of the apparent similarity of micro-branching instabilities in different brittle materials, we propose that the physics determining the typical length- and time-scales characterizing the post-instability patterns differ greatly from material to material. We offer a scaling theory connecting the pattern characteristics to material properties (like molecular weight) in brittle plastics like PMMA, and stress the fundamental differences with patterns in glass which are crucially influenced by 3-dimensional dynamics. In both cases the present ab-initio theoretical models are still too far from reality, disregarding some fundamental physics of the phenomena.Comment: 4 pages, 6 figures, PRL submitte

Dislocation plasticity in thin metal films

This article describes the current level of understanding of dislocation plasticity in thin films and small structures in which the film or structure dimension plays an important role. Experimental observations of the deformation behavior of thin films, including mechanical testing as well as electron microscopy studies, will be discussed in light of theoretical models and dislocation simulations. In particular, the potential of applying strain-gradient plasticity theory to thin-film deformation is discussed. Although the results of all studies presented follow a “smaller is stronger” trend, a clear functional dependence has not yet been established

Drip and Mate Operations Acting in Test Tube Systems and Tissue-like P systems

The operations drip and mate considered in (mem)brane computing resemble the operations cut and recombination well known from DNA computing. We here consider sets of vesicles with multisets of objects on their outside membrane interacting by drip and mate in two different setups: in test tube systems, the vesicles may pass from one tube to another one provided they fulfill specific constraints; in tissue-like P systems, the vesicles are immediately passed to specified cells after having undergone a drip or mate operation. In both variants, computational completeness can be obtained, yet with different constraints for the drip and mate operations

Lender Liability: A Survey of Common-Law Theories

Lender liability litigation has increased dramatically over the past several years. The increase in claims is hardly surprising when one considers recent multimillion dollar recoveries.\u27 Such well-publicized verdicts against lenders serve to encourage borrowers to defend even routine collection claims by striking out at the lender. Most often borrowers bring lender liability suits following commercial loan defaults. These suits are based on a number of common-law theories for liability including: breach of contract, breach of fiduciary duty,\u27 and breach of good faith, as well as fraud, duress, interference, and negligence. Some suits also raise statutory claims under the bankruptcy laws, the federal securities laws, the tax laws, the environmental laws,\u27 and the Racketeer Influenced and Corrupt Organizations Act (RICO).\u27 The success of many of these theories of liability has broadened the scope of lender liability and has helped borrowers fight back against overreaching lenders. Because many of the theories are relatively new to the banking area, however, courts have yet to define the theories\u27 parameters. This lack of judicial guidance leaves lenders in a difficult position. They face harsh economic consequences for failure to aid a troubled debtor, and potential liability if they do become involved. The uncertainty of the law makes it difficult for lenders to evaluate their risks. Consequently, evaluation has become more expensive. This evaluation expense and other increased costs eventually are passed onto borrowers and other bank customers. Furthermore, lenders often re-act by narrowing or curtailing important lending functions. Parts II and III of this Note describe the most prevalent theories of lender liability, focusing on common-law theories and highlighting prominent cases under each theory. Conflicts among jurisdictions are emphasized to show the need for guidelines and standardization. Part IV analyzes the impact of increased liability on lenders, and Part V examines the judiciary\u27s response depicted by several recent cases. Finally, Part VI concludes that until a body of law evolves in the area of lender liability, both lenders and borrowers will bear the costs of expanded and uncertain claims against lenders