Succinctness of pattern-based schema languages for XML

Martens et al. defined a pattern-based specification language equivalent in expressive power to the widely adopted XML Schema definitions (XSDs). This language consists of rules of the form $(r,s)$ where r and s are regular expressions and can be seen as a type-free extension of DTDs with vertical regular expressions. Sets of such rules can be interpreted both in an existential or universal way. In the present paper, we study the succinctness of both semantics w.r.t. each other and w.r.t. the common abstraction of XSDs in terms of single-type extended DTDs. The investigation is carried out relative to three kinds of vertical pattern languages: regular, linear, and strongly linear patterns. We also consider the complexity of the simplification problem for each of the considered pattern-based schemas.     

Numerical modelling of calcination reaction mechanism for cement production

Calcination is a thermo-chemical process, widely used in the cement industry, where limestone is converted by thermal decomposition into lime CaO and carbon dioxide CO₂. The focus of this paper is on the implementation and validation of the endothermic calcination reaction mechanism of limestone in a commercial finite volume based CFD code. This code is used to simulate the turbulent flow field, the temperature field, concentrations of the reactants and products, as well as the interaction of particles with the gas phase, by solving the mathematical equations, which govern these processes. For calcination, the effects of temperature, decomposition pressure, diffusion and pore efficiency were taken into account. A simple three-dimensional geometry of a pipe reactor was used for numerical simulations. To verify the accuracy of the modelling approach, the numerical predictions were compared with experimental data, yielding satisfying results and proper trends of physical parameters influencing the process.     

Robust Encryption

We provide a provable-security treatment of “robust” encryption. Robustness means it is hard to produce a ciphertext that is valid for two different users. Robustness makes explicit a property that has been implicitly assumed in the past. We argue that it is an essential conjunct of anonymous encryption. We show that natural anonymity-preserving ways to achieve it, such as adding recipient identification information before encrypting, fail. We provide transforms that do achieve it, efficiently and provably. We assess the robustness of specific encryption schemes in the literature, providing simple patches for some that lack the property. We explain that robustness of the underlying anonymous IBE scheme is essential for public-key encryption with keyword search (PEKS) to be consistent (meaning, not have false positives), and our work provides the first generic conversions of anonymous IBE schemes to consistent (and secure) PEKS schemes. Overall, our work enables safer and simpler use of encryption.     

Thermal diffusivity estimation using numerical inverse solution for 1D heat conduction

This work presents an improved apparatus and a numerical approach to obtain the estimate of thermal diffusivity of complex materials. Transient thermal response at the axis of cylindrical sample is measured when boundary temperature is suddenly changed. Instead of assuming an ideal step temperature excitement, a measured temperature of a material boundary was employed. An iterative procedure, based on minimizing a sum of squares function with the Levenberg–Marquardt method, is used to solve the inverse problem. A graphical user interface is built to enable easy use of the inverse thermal diffusivity estimation method. The reference materials used to evaluate the method are Agar water gel, glycerol and Ottawa quartz sand.     

Modeling the energy potential of biomass – H2RES

Modeling biomass as a renewable energy source poses many challenges with respect to feedstock variability, which are difficult to account for. It is found that at the preliminary stages of energy planning, heating value and moisture content of the feedstock are the most important factors. In addition, the effects of harvesting, transportation and storage are found to be significant even though they are often overlooked. Using the gathered information a biomass module for energy planning is created and integrated to H₂RES, a renewable energy planning program. Using this excel based software, a case study for a wood processing factory is performed, using the waste wood as feedstock. Comparing various scenarios, it is concluded that using a combination of solid oxide fuel cells, solar panels and steam turbines can satisfy the factories energy requirements with excess sold to the grid.     

Thermal properties of hydrating calcium aluminate cement pastes

As the hydration of calcium aluminate cements (CAC) is highly temperature dependent, yielding morphologically and structurally different hydration products that continuously alter material properties, a good knowledge of thermal properties at early stages of hydration is essential. Thermal diffusivity and thermal conductivity during CAC hydration was investigated by a transient method with a numerical approach and a transient hot wire method, respectively. For hydration at 15 °C (formation of mainly CAH₁₀), thermal diffusivity shows a linear decrease as a function of hydration degree, while for hydration at 30 °C there is a linear increase of thermal diffusivity. Converted materials exhibited the highest values of thermal diffusivities. The results on sealed converted material indicated that thermal conductivity increased with an increase in temperature (20-80 °C), while thermal diffusivities marginally decreased with temperature. The Hashin-Shtrikman boundary conditions and a simple law of mixtures were successfully applied for estimating thermal conductivity and heat capacity, respectively, of fresh cement pastes.     

Transitive signatures: new schemes and proofs

We present novel realizations of the transitive signature primitive introduced by Micali and Rivest, enlarging the set of assumptions on which this primitive can be based, and also providing performance improvements over existing schemes. More specifically, we propose new schemes based on factoring, the hardness of the one-more discrete logarithm problem, and gap Diffie-Hellman (DH) groups. All these schemes are proven transitively unforgeable under adaptive chosen-message attack in the standard (not random-oracle) model. We also provide an answer to an open question raised by Micali and Rivest regarding the security of their Rivest-Shamir-Adleman (RSA)-based scheme, showing that it is transitively unforgeable under adaptive chosen-message attack assuming the security of RSA under one-more inversion. We then present hash-based modifications of the RSA, factoring, and gap Diffie-Hellman based schemes that eliminate the need for "node certificates" and thereby yield shorter signatures. These modifications remain provably secure under the same assumptions as the starting scheme, in the random oracle model.