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.     

The master sintering curves for BaTi0.975Sn0.025O3/BaTi0.85Sn0.15O3 functionally graded materials

The most important aim in the design and processing of functionally graded materials (FGMs) is to produce devices free from any deformation. Smart choices of different combination of graded layers, as well as the heating rate during sintering, are important for the fabrication of high-quality FGMs. In this study, BaTi_0.975Sn_0.025O₃/BaTi_0.85Sn_0.15O₃ (noted as BTS2.5 and BTS15, respectively) FGM was used as a model system for the construction of master sintering curves (MSCs) and estimation of the effective activation energies of sintering for different BTS graded layers. The MSCs were constructed, for BTS2.5 and BTS15 graded layers in FGMs, using shrinkage data obtained by a heating microscope during sintering at four constant heating rates, 2, 5, 10 and 20 °/min. The effective activation energies were determined using the concept of MSC; values of 359.5 and 340.5 kJ/mol were obtained for graded layers BTS2.5 and BTS15, respectively. A small difference of the effective activation energies of chosen powders made it possible for us to prepare high-quality FGMs, without delamination, distortion or other forms of defects.     

Correlation among sintering process,porosity, and creep deformation of refractory concrete

The aim of this paper is to establish the correlation among sintering process, porosity, and important thermo-mechanical property of refractory concrete, i.e., creep. Creep deformation was investigated according to the standard laboratory procedure applied at three temperatures: 1200, 1300, and 1400 °C. Corundum and bauxite-based refractory concretes were investigated. The concretes are varying in chemical and mineralogical composition. Both loss of strength and degradation of material occur when refractory concrete is subjected to increased temperature and compressive static load. Measuring of thermo-mechanical properties can indicate and monitor the changes within microstructure. Variation of refractory concrete microstructure, as a consequence of sintering process, during exposure to constant compressive load and constant elevated temperature during certain time-intervals was investigated using scanning electron microscope and Image Pro Plus program for image analysis. Obtained results of the investigation proved that creep can be useful method when type of refractory concrete is to be chosen for an application.     

Measurement of the transient electrical and shaft torques in an induction motor drive by the indirect two-speed method

Contents This paper presents a new method, called Indirect Two-Speed Method (ITSM), for obtaining electrical and shaft torques in an induction motor drive by means of measuring the speeds of both lumped-inertia elements assigned to a second order model. The measuring is realized by using high-resolution digital tachometers (represented by incremental encoders), two frequency measurement systems based on the Double-Buffered Method, digitalfiltering of the raw speed data and numerical differentiation of the filtered speed data.

---

Messung transienter Drehmomente eines Induktionsmotor-Antriebs mittels der Indirekten Zwei-Drehzahlen-Methode

Übersicht Im Beitrag wird ein neues Verfahren zur Ermittlung des elektrischen Moments und des Wellen-Drehmoments eines Induktionsmotor-Antriebs vorgestellt. Das als Indirekte Zwei-Drehzahlen-Methode (ITSM) bezeichnete Verfahren geht aus von einem mechanischen Modell zweiter Ordnung und mißt die Drehzahlen beider als konzentrierte Parameter betrachteten Drehmassen. Für die Durchführung werden hochauflösende digitale Tachometer eingesetzt. Die Frequenzmessung erfolgt durch ein Verfahren mit doppelter Pufferung, und es werden die Rohdaten nach digitaler Filterung numerisch differenziert.

     

One-step decomposition method for numerical integration of short- and long-term dynamics

A mathematical model is derived and disdussed that represents the structural properties of the alternative linearity and of the triangular block structural connectivity of the sets of differential equations, associated with the machines in the numerical integration of short- and long-term dynamics. In order to take into consideration the structural properties of the model, a one-step decomposition method for the numerical integration of short- and long-term dynamics is proposed. The method can be applied not only to the numerical integration of short- and long-term dynamics but also to all other cases when the model of the dynamic system is alternative-linear and triangular block connected. Numerical stability, accuracy and computation speed are the major advantages of this method, making it suitable for many applications, including the dynamic security analysis of power systems.     

Specific Heat and Electrical Resistivity of 53%Niobium-47%Titanium Alloy Measured by Subsecond Calorimetric Technique

This paper presents results of measurements of the specific heat and electrical resistivity of a 53%Ni-47%Ti superconducting alloy. Both properties were measured by a contact variant of the millisecond-resolution pulse calorimeter. W5%Re/W25%Re thermocouple thermometry enabled study from ambient temperature to 2000 K. Results are discussed, and their uncertainty is estimated.     

Effect of suspended particulate-size distribution on the backscattering ratio in the remote sensing of seawater

Mie theory is used to study the influence of the particle-size distribution (PSD) on the backscattering ratio for case 1 and 2 waters. Several in situ measured PSDs from coastal water and the open ocean, representing typical case 2 and 1 waters, were used in this investigation. Calculation of the backscattering ratio requires integration of the PSD over a much broader size range than is usually measured. Consequently extrapolation from fitted data is necessary. To that purpose the measured data are fitted with hyperbolic (Junge) and the two-component model of the PSD. It is shown that the result of extrapolation, hence the backscattering ratio, critically depends on the chosen PSD model. For a particular PSD model the role of submicrometer particles and the applied integration limits on the backscattering ratio is discussed. The use of the hyperbolic PSD model largely overestimates the number of small (submicrometer) particles that significantly contribute to backscattering and consequently leads to an erroneously high backscattering ratio. The two-component model proves to be an adequate PSD model for use in backscattering/scattering calculations providing satisfactory results complying with experimental data. The results are relevant for the inversion of remotely sensed data and the prediction of optical properties and the concentration of phytoplankton pigments, suspended sediment, and yellow substance.     

Crystallization behavior of calcium phosphate glass powder

The crystallization behavior of calcium phosphate glass powder with the molar ratio [CaO]/[P₂O₅] = 0.88, to which 6.38 mol% TiO₂ and 10 mol% Al₂O₃ were added as nucleation agents, was investigated. The results indicate complex crystallization behavior which depends on the powder particle size and the crystallization temperature. In the crystallization temperature range T _c < 900°C the surface mechanism of crystallization dominates in the case of all particle sizes ranging from 0–1 mm and the -Ca₂P₂O₇ phase is formed. At very long annealing times volume crystallization occurs and the TiP₂O₇ and AlPO₄ phases are formed. In the temperature interval T _c > 900°C the dominant crystallization mechanism depends on the particle size. In the size range 0.15–0.5 mm the surface mechanism of crystallization is replaced by the volume one. In the range >0.5 mm the volume mechanism of crystallization is dominant. The phases -Ca₂P₂O₇, TiP₂O₇ and AlPO₄ are formed in that temperature interval for all particle sizes. The additives TiO₂ and Al₂O₃ influence the nucleation and formation of TiP₂O₇ and AlPO₄ but do not influence the formation of -Ca₂P₂O₇.     

Dosimetric characteristics of Li2B4O7:Cu,Ag,P solid TL detectors

A two-mutation carcinogenesis (TMC) model is used as a bridge between cellular radiation biological effects and the incidence of cancer. This model has been applied to several sets of experimental animal and epidemiological data. In this paper the advantage of the model and the implications for radiation risks at low doses are discussed with respect to the age and dose dependence of cancer incidence and the effect of age at exposure on radiation risk; the link between the radiation effect and background cancer incidence and the transfer of radiation risk across different population groups; the implications of acute and protracted radiation exposures for risks at low doses and the dose-effect relationship for radium induced bone cancer.