Shrinkage-Free Sintering of Low-Temperature Cofired Ceramics by Loading Dilatometry

Sintering with zero radial shrinkage of low-temperature cofired ceramics (LTCC) was investigated by means of loading dilatometry. The results indicate that constant compressive loads tend to produce either decreased or increased radial shrinkages, and this can vary as a function of density, depending on the magnitude of the applied stresses. Coupling the real-time applied uniaxial load to the radial strain of cylindrical samples afforded a sintering scheme where the radial strain was precisely kept near zero (±0.02%). This approach possibly perfects an existing hot-pressing technique for zero-shrinkage sintering technology of LTCC materials.     

Production of CO during burnup of (Th,U)O2 kerneled HTR fuel particles

The CO content of irradiated (Th, U)O₂ kerneled HTR fuel particles has been measured by mass spectrometry. An evaluation of all the data thus obtained showed that the oxygen release, O/f (atoms per fission), during irradiation is governed by thermodynamic equilibrium; O/f is a function of the irradiation temperature $\text{T}$(K), the initial Th/U-235 ratio $\text{N}$, and the burnup $\text{F}$ (fissions per initial heavy metal atom). Within the limits of $\text{1073 < T < 2273}$, $\text{4 < N <50}$, and $\text{0.04 < F < 0.17}$, the oxygen release can be represented by the expression $\text{log}{}_{10}\text{O/f = 0.96 ? 4420/T + 0.4 log}{}_{10}\text{N + 0.3 log}{}_{10}\text{F}$.The attainment of equilibrium proceeds rather slowly; at 1473 K it takes about 130 h to reach 99% of the equilibrium value.Coated particles which had undergone large fission-product losses showed significantly increased oxygen release values.     

Some regional costs of a synthetic fuel industry: The case of illinois

The Federal Government's efforts to induce development of a coal-based synthetic fuel industry include direct subsidies, tax concessions, and assurances that it will purchase the industry's output, even if above the market price. In this note it is argued that these subsidies will enable this industry to secure a region's largest and lowest-cost coal deposits and that the costs imposed on other coal users will be substantial. Moreover, because the lowest-cost coal deposits will be committed to synthetic fuels production regardless of the industry's commercial viability, distortions in regional coal markets will develop. If economic efficiency requires that the price of the resource reflect its replacement value, then a State government is justified in imposing a tax on coal destined for subsidized synthetic fuel plants. Amounts of such a tax, based on the higher costs of coal that must be accepted by other users as the result of the subsidized synthetic fuel plants' preempting the largest and lowest-cost deposits, are estimated for the case of Illinois strippable coal.     

Exploring Tabular Verification and Refinement

Tabular representations have been proposed for structuring complex mathematical expressions as they appear in the specification of programs. We argue that tables not only help in writing and checking complex expressions, but also in their formal manipulation. More specifically, we explore the use of tabular predicates and tabular relations in program verification and refinement.     

Modelling LTE Solved Troubleshooting Cases

Self-Organizing Networks (SON) add automation to the Operation and Maintenance of mobile networks. Self-healing is the SON function that performs automated troubleshooting. Among other functions, self-healing performs automatic diagnosis (or root cause analysis), that is the task of identifying the most probable fault causes in problematic cells. For training the automatic diagnosis functionality based on support-decision systems, supervised learning algorithms usually extract the knowledge from a training set made up from solved troubleshooting cases. However, the lack of these sets of real solved cases is the bottleneck in the design of realistic diagnosis systems. In this paper, the properties of such troubleshooting cases and training sets are studied. Subsequently, a method based on model fitting is proposed to extract a statistical model that can be used to generate vectors that emulate the network behavior in the presence of faults. These emulated vectors can then be used to evaluate novel diagnosis systems. In order to evaluate the feasibility of the proposed approach, an LTE fault dataset has been modeled, based on both the analysis of real cases collected over two months and a network simulator. In addition, the obtained baseline model can be very useful for the research community in the area of automatic diagnosis.     

Single Shot Dual-Wavelength Digital Holography: Calibration Based on Speckle Displacements

We present a calibration method which allows single shot dual wavelength online shape measurement in a disturbed environment. Effects of uncontrolled carrier frequency filtering are discussed as well. We demonstrate that phase maps and speckle displacements can be recovered free of chromatic aberrations. To our knowledge, this is the first time that a single shot dual wavelength calibration is reported by defining a criteria to make the spatial filtering automatic avoiding the problems of manual methods. The procedure is shown to give shape accuracy of 35 µm with negligible systematic errors using a synthetic wavelength of 1.1 mm.     

Pozzolanic reactions of six principal clay minerals: Activation, reactivity assessments and technological effects

Six standard clays, before and after calcination at 3 or 4 temperatures and being mixed with Ca(OH)₂ [CH] in the presence of simulated cement pore solution, and with ordinary Portland cement, respectively, were studied in detail. Chemical compositions of most clays conform well to the requirement in ASTM C 618. Water demand of clay-containing mortar varies, depending on the crystal chemistry of raw clays, and on the specific surface area of calcined clays. Measurements of XRD background or alkali soluble Si are rapid methods in evaluation of the pozzolanic activity of clays. Compressive strength of mortars based on the raw clays is affected by structure of clays. Calcination increases the pozzolanic activity of clays and the compressive strength of the Portland cement — clay mortars. A close correlation exists between compressive strength of mortars and particle size distribution of the dehydroxylated clays. The most common reaction products of clay — CH mixtures are C-S-H² and C₄AH_x, while C₂ASH_j8 and C₃AH₆ were also detected with clays rich in Al.     

New polyurethane cationomers with naphthyl and phenyltriazene pendants: Synthesis and properties

Two new diols bearing triazene moiety, 1‐(α‐naphthyl)‐3,3‐di(2‐hydroxyethyl) triazene‐1 (NT‐D) and 1‐phenyl‐3,3‐di(2‐hydroxyethyl) triazene‐1 (PT‐D), were synthesized from aromatic amines and diethanolamine. These monomers were used as chain coextenders in the two‐step addition reaction between poly(tetramethylene oxide) diol, 2,4‐tolylene diisocyanate, and N‐methyldiethanolamine to obtain photosensitive polyurethanes of elastomer type. Triazene polyurethane cationomers with chlorine counterions were prepared via a quaternization reaction of the above polymers with benzyl chloride. All polyurethanes had a quantity of triazene units between 7.02 and 8.93 wt % polymer, and the content of ammonium quaternary groups in the cationic ones was of 30.56 meq/100 g naphthyl triazene polyurethane cationomer (PUC‐NT) and 30.19 meq/100 g phenyl triazene polyurethane cationomer (PUC‐PT), respectively. Photobehavior of the triazene units in all polymers under continuous Hg‐lamp irradiation was similar to that found for monomers, when both chromophores were transformed during UV irradiation. It is concluded that the PT‐D acts as a more efficient sensitizer in the UV light‐induced reaction but the photolysis in elastomeric films was lower than that observed in solution. The presence of quaternary ammonium structure on the same polymer backbone decreases the constant rates of photolysis. Because the triazene polyurethanes become crosslinked during UV irradiation could be assessed as potential negative‐resist polymers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2599–2605, 2004     

Proof Complexity of the Cut-free Calculus of Structures

We investigate the proof complexity of analytic subsystems ofthe deep inference proof system SKSg (the calculus of structures).Exploiting the fact that the cut rule (i) of SKSg correspondsto the ¬-left rule in the sequent calculus, we establishthat the ‘analytic'system KSg+c has essentially the samecomplexity as the monotone Gentzen calculus MLK. In particular,KSg+c quasipolynomially simulates SKSg, and admits polynomial-sizeproofs of some variants of the pigeonhole principle.     

Stable and convergent iterative feedback tuning of fuzzy controllers for discrete-time SISO systems

This paper proposes new stability analysis and convergence results applied to the Iterative Feedback Tuning (IFT) of a class of Takagi–Sugeno–Kang proportional-integral-fuzzy controllers (PI-FCs). The stability analysis is based on a convenient original formulation of Lyapunov’s direct method for discrete-time systems dedicated to discrete-time input affine Single Input-Single Output (SISO) systems. An IFT algorithm which sets the step size to guarantee the convergence is suggested. An inequality-type convergence condition is derived from Popov’s hyperstability theory considering the parameter update law as a nonlinear dynamical feedback system in the parameter space and iteration domain. The IFT-based design of a low-cost PI-FC is applied to a case study which deals with the angular position control of a direct current servo system laboratory equipment viewed as a particular case of input affine SISO system. A comparison of the performance of the IFT-based tuned PI-FC and the performance of the PI-FC tuned by an evolutionary-based optimization algorithm shows the performance improvement and advantages of our IFT approach to fuzzy control. Real-time experimental results are included.