Function Estimation by Feedforward Sigmoidal Networks with Bounded Weights

We address the problem of estimating a function f: [0,1] ^d [-L,L] by using feedforward sigmoidal networks with a single hidden layer and bounded weights. The only information about the function is provided by an identically independently distributed sample generated according to an unknown distribution. The quality of the estimate is quantified by the expected cost functional and depends on the sample size. We use Lipschitz properties of the cost functional and of the neural networks to derive the relationship between performance bounds and sample sizes within the framework of Valiant's probably approximately correct learning.     

Robot-assisted shopping for the blind: issues in spatial cognition and product selection

Research on spatial cognition and blind navigation suggests that a device aimed at helping blind people to shop independently should provide the shopper with effective interfaces to the locomotor and haptic spaces of the supermarket. In this article, we argue that robots can act as effective interfaces to haptic and locomotor spaces in modern supermarkets. We also present the design and evaluation of three product selection modalities—browsing, typing and speech, which allow the blind shopper to select the desired product from a repository of thousands of products.     

One-pot synthesis of cyclodextrins, modified with poly(ethylene oxide)

A new series of bouquet-like molecules based on cyclodextrins (CD) is described. They result from the polymerization of ethylene oxide initiated by hydroxyl groups of cyclodextrins, that constitutes the organizing core. Analysis of the structure and composition of the conjugates based on α-, β- and γ-CDs was done using ¹³C-NMR and data of molecular mass of conjugates. Glass transition behavior of conjugates shows that they are amorphous compounds. Received: 29 April 1996/Revised: 2 January 1997/Accepted: 23 January 1997     

Client-server design provides model for 'coopetition' alliances

As healthcare organizations move from isolated departments to integrated information sharing, who will pilot this change? Both the director and manager of pathology data systems at the University of Michigan Hospitals in Ann Arbor suggest vendors, system integrators and hospital administrators put aside competition and try a new concept--"coopetition"--to solve the problem.     

Structure of Urethane Copolymers of 3,3‐Bis(azidomethyl)oxetane and 3‐Azidomethyl‐3‐methyloxetane

Polyurethane copolymers of 3,3‐bis (azidomethyl) oxetane (BAMO) and 3‐azidomethyl‐3‐methyloxetane (AMMO) with molecular structures of types B(AB)n, A(AB)n, (BB)n and ABn with different ratios of oligomeric units were investigated, where A is the non‐crystallizable “soft” block of oligoAMMO and B is the “hard” block of oligoBAMO and the included urethane diol fragments. The amorphous‐crystalline structures of copolymers BAMO and AMMO were elucidated by wide angle X‐ray diffraction measurements. The influences of the molecular structure and the ratio of oligomeric units on the structural parameters were identified. The degree of crystallinity is in a range from 8 to 22 % and sizes of the crystallites were determined. The defectivenesses of first and second kind in the structure were evaluated, which show high values of the first kind defectiveness (approx. 20 %), which describes the displacement of theoretical lattice sites and the existence of unequal sizes of the lattice sites, and minor values for the second kind defectiveness (approx. 3 %), which describes the lattice site disorder in large distances. Small‐angle X‐ray diffraction measurements were used to investigate the domain structures of copolymers BAMO and AMMO. The distribution and sizes of the crystallites in the structures of the copolymers were calculated.     

Hydrogen Production from Methane and Carbon Dioxide by Catalyst-Assisted Chemical Looping

Hydrogen can be produced from a mixture of CH₄ and CO₂, based on chemical looping techniques. A physical mixture of a Ni/Al₂O₃ catalyst and Fe₂O₃?CCeZrO₂ as oxygen storage material is used in the chemical looping. During the reduction step, CH₄/CO₂ is converted over Ni/Al₂O₃ into syngas, which then reduces iron oxide, giving CO₂ and H₂O. During re-oxidation of the oxygen storage material by steam, H₂ with ppm levels of CO_x is produced.     

Thermoplastic modification of medical grade polyvinyl chloride with various antibiotics: effect of antibiotic chemical structure on mechanical,antibacterial properties,and release activity

Novel polymeric systems with antibacterial properties based on medical-grade polyvinyl chloride and antibiotics (Ampicillin, Minocycline, and Rifampicin) in the concentrations up to 1 wt% were prepared by thermoplastic compounding. Thermal stability of the antibiotics was corroborated by IR spectroscopy, X-ray diffraction, differential scanning calorimetry, and ¹H nuclear magnetic resonance spectroscopy. The effect of chemical structure on mechanical properties of the prepared systems was determined by tensile testing measurements and correlated with optical microscopy observations. In vitro antibacterial properties of samples were determined by agar diffusion and adhesion test against Gram-negative and Gram-positive bacteria. Antibiotic release experiments in distilled water and physiological saline solution and follow-up detecting by Ultraviolet–Visible spectroscopy were carried out. A mathematical model was applied to evaluate the release kinetics of the antibiotics from prepared polymeric systems. The results show significant influence of antibiotic’s chemical structure on all studied characteristics of the systems due to the various interactions with polyvinyl chloride matrix.     

Numerous Applications of Fiber Optic Evanescent Wave Fourier Transform Infrared (FEW–FTIR) Spectroscopy for Surface and Subsurface Structural Analysis

A new infrared (IR) interferometric method has been developed in conjunction with low-loss, flexible optical fibers, sensors, and probes. This combination of fiber optical sensors and Fourier Transform (FT) spectrometers can be applied to many fields, including: (i) noninvasive medical diagnostics of cancer and other different diseases in vivo; (ii) minimally invasive bulk diagnostics of tissue; (iii) remote monitoring of tissue, chemical processes, and environment; (iv) surface analysis of polymers and other materials; (v) characterization of the quality of food, pharmacological products, cosmetics, paper, and other wood-related products, as well as (vi) agricultural, forensic, geological, mining, and archeological field measurements. In particular, our nondestructive, fast, compact, portable, remote, and highly sensitive diagnostics tools are very promising for subsurface analysis at the molecular level without sample preparation. For example, this technique is ideal for different types of soft porous foams, rough polymers, and rock surfaces. Such surfaces, as well as living tissue, are difficult to investigate by traditional FTIR methods. We present here FEW–FTIR spectra of polymers, banana and grapefruit peels, and living tissues detected directly at surfaces. In addition, results on the vibrational spectral analysis of normal and pathological skin tissue in the wavenumber region 850–4000cm^–1 are discussed.     

PARAMETRIC GENERATION OF SINGLE-PHASE PROPERTIES (P-T CURVES) FOR MOST CUBIC EQUATIONS OF STATE AND ANY MIXING RULES

A simple method is proposed for the calculation of any type of P-T curve for the most general case of two-parameter equations of state in the single-phase area. For each component parameter, temperature dependency can be expressed on the basis of any analytical function; for the mixture, any mixing rule can be considered for any parameter. For the construction of these curves, the numerical algorithm is completely described. This method is illustrated for the Joule-Thomson inversion and Boyle curves.