Reduced-basis techniques for rapid reliable optimization of systems described by affinely parametrized coercive elliptic partial differential equations

We present a technique for the rapid and reliable optimization of systems characterized by linear-functional outputs of coercive elliptic partial differential equations with affine (input) parameter dependence. The critical ingredients are: reduced-basis approximation to effect significant reduction in state-space dimensionality; a posteriori error bounds to provide rigorous error estimation and control; “offline/online” computational decompositions to permit rapid evaluation of output bounds, output bound gradients, and output bound Hessians in the limit of many queries; and reformulation of the approximate optimization statement to ensure (true) feasibility and control of suboptimality. To illustrate the method we consider the design of a three-dimensional thermal fin: Given volume and power objective-function weights, and root temperature “not-to-exceed” limits, the optimal geometry and heat transfer coefficient can be determined—with guaranteed feasibility—in only 2.3 seconds on a 500 MHz Pentium machine; note the latter includes only the online component of the calculations. Our method permits not only interactive optimal design at conception and manufacturing, but also real-time reliable adaptive optimal design in operation.     

Framework flexibility of sodium zirconium phosphate: role of disorder, and polyhedral distortions from Monte Carlo investigation

A detailed Monte Carlo investigation of the structural changes of the framework of sodium zirconium phosphate, [Zr₂P₃O₁₂]⁻,—NASICON (acronym for Na-SuperIonic CONductor)—accommodating alkali ions of varying sizes (Li⁺, Na⁺, K⁺, Rb⁺ and Cs⁺) is carried out over a range of temperatures. Simulation results are critically compared with the structural models proposed earlier and available experimental results. Anisotropic changes of the rhombohedral cell parameters—a contracts while c expands with the size of the alkali ion substituted—is observed in good agreement with previous experimental results. The mechanism of anisotropic variation of lattice parameters involves dominantly, coupled rotations of the polyhedra as proposed by Alamo and co-workers. It is, however, observed that the distortions of the PO₄ tetrahedra and ZrO₆ octahedra are significant, and accounts for nearly one-third of the total change in a and c—parameters as the size of the alkali ion increases. This suggests that ‘rigid’ polyhedral models, permitting only angular distortions of the polyhedra, are of limited quantitative applicability in these solids. The same mechanism is found to be responsible for the low/anisotropic thermal expansion of these solids. Evidence that the polyhedral rotations are dynamic, opposed to a static-frozen-in disorder, is provided.     

Computing Parametric Geometric Resolutions

 Given a polynomial system of n equations in n unknowns that depends on some parameters, we define the notion of parametric geometric resolution as a means to represent some generic solutions in terms of the parameters. The coefficients of this resolution are rational functions of the parameters; we first show that their degree is bounded by the Bézout number d ⁿ , where d is a bound on the degrees of the input system. Then we present a probabilistic algorithm to compute a parametric resolution. Its complexity is polynomial in the size of the output and in the complexity of evaluation of the input system. The probability of success is controlled by a quantity polynomial in the Bézout number. We present several applications of this process, notably to computa- tions in the Jacobian of hyperelliptic curves and to questions of real geometry. Received: July 5, 2001; revised version: September 5, 2002 Key words: Polynomial systems with parameters, Complexity, Theory of elimination, Symbolic Newton operator.     

Functional approach to the Rayleigh-Bénard problem for a nematic liquid crystal

The derivation of a functional analog of the free energy—the generalized thermodynamic potential— for an open system such as a nematic liquid crystal in a temperature gradient field is proposed. Near the threshold of thermal convection all the hydrodynamic variables can be described by a single complex amplitude w, the order parameter of the system, which enables one to determine the spatial position and the intensity of rotation of the convection rolls that arise. The orthogonality condition for the solutions is shown to yield an Euler equation from which one can recover the generalized thermodynamic potential, the extrema of which correspond to the most probable realizations of the dissipative structures. Pis’ma Zh. Tekh. Fiz. 24, 6–12 (June 26, 1998)     

The global science base of information and communication technologiges: Bibliometric analysis of ICT research papers

The science and engineering base is a key source of knowledge for the development and use of Information and Communication Technologies (ICTs). In order to be able to effectively describe and monitor world-wide scientific activity related to ICTs, it is important to be able to provide reliable macro-level statistics of this knowledge base. International bibliographic databases and related bibliometric indicators together provide an analytical framework and appropriate measures to cover both the ‘supply side’—research capabilities and outputs—and ‘demand side’—collaboration, diffusion and citation impact—related to the ICT research. This paper presents results of such a bibliometric study describing macro-level features of this ICT knowledge base. The data were retrieved from a specially developedCWTS ICT Database which provides a broad-scope world-wide coverage of ICT-relevant research papers published in high-quality international scientific and technical journals. The cross-country comparison focuses on the level of scientific output and co-operation patterns of the most actively publishing nations with a focus on the three Triad zones—the European Union, the USA and Japan.     

The effect of adding organic polymers on the handling properties, strengths and bioactivity of a Ca–Sr–Zn–Si glass polyalkenoate cement

This work demonstrates the addition of a number of naturally occurring proteins/polymers to a zinc based glass polyalkenoate cements (GPCs). Chitin (Chi.), collagen (Col.), cysteine (Cys.) and keratin (Ker.) were added with the intention of improving the bioactivity of this cement. Initial testing involved characterization of the glass with X-ray diffraction (XRD) and differential thermal analysis (DTA) before and after sterilization with γ-irradiation. No significant changes occurred as a result of sterilization. Handling properties of the modified cements were not significantly different from those of the control, BT 101 (Working T _w—36 s, and setting time T _s—70 s) except for Chi. (30 s, p ≤ 0.016) and Cys. (105 s, p ≤ 0.0001) respectively. Comparison of the mechanical properties of BT 101 (compression—σ_c and biaxial flexural—σ_f) to the modified cements revealed a significant decrease in σ_c with Chi. and Col., after 1, 7 and 30 days. However, there were little changes occurring in σ_f. Cement structural testing was investigated and found that the addition of these polymers greatly reduced the cements surface area, however, the only significant change to occur in the solubility testing was Ker. (p ≤ 0.009). Simulated body fluid (SBF) testing resulted in increased calcium phosphate (CaP) deposition of Chi. and Col. compared to BT 101. Cell culture studies determined only Col. significantly increased (p ≤ 0.0001) in comparison to the control cement.     

Characterization of granular silicon,powders, and agglomerates from a fluidized bed reactor

Growth of polycrystalline silicon from fluidized bed reactors (FBR) produces two general types of silicon products: granular material (diameters on the order of mm) and homogeneously nucleated material often called nanopowder (diameters in the range 10–100 nm). Nanopowder particles tend to be amorphous and have a spherical morphology with an average particle diameter of ~80 nm. Granular material is generally spherical, highly twinned, polycrystalline with crystallite sizes that can reach 200 nm, and includes regions of porosity. The porosity is ~1–4 volume percent, and only the smallest pores exhibit evidence of amorphous regions along the pore surface. The amount of nanopowder that agglomerates on the granular material has been identified using transmission electron microscopy, but agglomeration plays only a minor role in the overall growth process. Therefore, it is proposed that the primary mechanism for granular formation in commercial FBR is chemical vapor deposition, and the pores are associated with nanopowder agglomeration and incomplete sintering.     

Fuzzy logic controller to improve parameters affecting gas turbines power generation

In order to improve the performance of the gas turbine power plant and to generate electricity at the best cost, a fuzzy logic controller model was used to show the effect of different parameters on the power generation output of gas turbines. The proposed methodology was applied to certain parameter values collected from Rehab power station in Jordan—as a case study—for validation purposes. Relative weights were used, i.e., very very low power generation “extremely low power generation,” very low power generation, low power generation, normal power generation, high power generation, and very high power generation. The study reveals that the major factors that affect yield are ambient temperature (T ₁), compressor’s exit temperature (T ₂), turbine’s inlet temperature (T ₃), turbine exit temperature (T ₄), pressure ratio (R _p), mass of fuel (M _f), relative humidity (H), turbine efficiency (η_t), and compressor efficiency (η_c). Based on the increase of productivity, the results show that different factors are found to affect the yield of a power generator. Therefore, using fuzzy logic controller model has lead the researchers to focus on the highest priority parameters that should be enhanced and developed to increase the power output productivity.     

Toluene removal in membrane bioreactors under recirculating and non-recirculating liquid conditions

A single-, dual- and multiple-tube dense phase silicone rubber membrane bioreactor were investigated for control of toluene-contaminated air under circulating and non-recirculating liquid conditions. A mathematical model was developed to describe the system. The reactors were seeded with a mixed bacterial consortium isolated from activated sludge and capable of aromatic biodegradation. After operating with recirculating liquid nutrient solution, the reactors were operated with no recirculation of the liquid, for 50 days or more in each instance. Average toluene removal measured in the single-tube reactor was 93 ppm with recirculating liquid and 102 ppm without recirculation of the liquid. Average removal measured in the dual-tube reactor was 396 ppm with recirculating liquid and 319 ppm without recirculation of the liquid. Operation under stagnant liquid conditions had no significant detrimental impact on bioreactor performance. Biokinetic parameters were measured for both the suspension and biofilm with values of the maximum specific utilization rate values (k) ranging from 0.01 to 0.42 h⁻¹ and half saturation constant values (K _S) ranging from 1.5 to 14.3 mg L⁻¹. Results suggest that membrane bioreactors might be operated under non-recirculating liquid conditions without performance detriment, reducing or eliminating the energy requirements and costs associated with pump operation.     

Structural transformations in amorphous As x Se1−x (0 ≤ x ≤ 0.20) films

Structural transformations are examined by the employment of Raman scattering measurements for amorphous Se-rich As _x Se_1−x (0 ≤ x ≤ 0.2) alloys. It is found that the molecular structure of amorphous Se (a-Se) on the scale of medium-range order differs from the structure of most inorganic glasses and may be placed between 3-dimensional network glasses and polymeric ones. Further experiments show the existence of successive phases in laser-induced glass—crystalline transition with pronounced threshold behavior. By comparing peak width, peak location and Raman intensity in the range of bond modes it is derived that the changes occur not monotonically with increasing As content. The composition-induced changes of the spectra are explained by cross-linking of Se chains. Under laser irradiation, the changes in the optical transmission, holographic recording properties and Raman spectra of amorphous As _x Se_1−x films with 0 < x ≤ 0.2 have been examined. The dependence of the transmissivity and diffraction efficiency on the irradiation energy density shows two qualitatively different regions. Below the energy density threshold, E _th, only small changes in the local structure of the system can be detected. In the low-energy region, transient changes in transmissivity are observed. Qualitative explanation of this behavior may be based on associating such with alternating of deep defect states. Above E _th, the changes were attributed to crystallization transformation. The corresponding Raman spectra reveal transformation of the system from amorphous into the crystalline phase under laser irradiation. Although several articles and texts have provided reviews on various properties and applications of chalcogenide glasses, there is no thorough study of local atomic structure and its modification for Se-rich amorphous As _x Se_1−x . The present paper is concerned with this problem.     

Possible Implications of the Principle of the ‘<Emphasis Type="Italic">Mise en Pratique</Emphasis>’ in its Application to the Kelvin

In 2005, the CIPM, in accepting CCT Recommendation T3, made a substantial change in the definition of the quantity ‘temperature’ by transforming the written standards for temperature (the “temperature scales”) into implementations of the mise en pratique of the kelvin. Having considered “that the creation of a formal mise en pratique of the definition of the kelvin would considerably simplify and clarify statements and recommendations of the CCT concerning the realization of the definition of the kelvin and the implementation of practical temperature scales,” the CIPM decision transformed the present ITS-90 and PLTS-2000 into two ways to implement the mise en pratique, with the possibility to further define “in due course” in the mise en pratique “recommendations concerning the direct determination of thermodynamic temperature.” The paper presents the author’s views regarding possible implications for the concept of a mise en pratique when applied to the kelvin beyond the present implementation. One possibility is to promote the formal use and status of realizations of the thermodynamic scale that, in practice, today only represents the physical basis of an empirical scale like the ITS-90. Another path arises from assuming that the only technical limit placed on the addition of further methods to the mise en pratique is that they be compatible with one another, to avoid ambiguities in the definition of the temperature values, though without the constraint of having the same, or comparable, accuracy. As a consequence, other scales that are currently considered ‘approximations’ to the ITS-90, with no formal status other than possibly being ‘recommended’ by some official body, such as the CCT WG2, could be upgraded to implementations of the mise en pratique, though with accuracy—and precision—inferior to that of the ITS-90. This would assist the vast majority of the users of temperature scales, and could be expected to increase the support of the worldwide thermal community for the work performed by the CCT. This possibility has so far been prevented by the need to define a single written standard at only the highest state-of-the-art accuracy level, the rest being left to sparse efforts, often devoid of traceability to the written standard.     

Fiber-reinforced hyperelastic solids: a realizable homogenization constitutive theory

A new homogenization theory to model the mechanical response of hyperelastic solids reinforced by a random distribution of aligned cylindrical fibers is proposed. The central idea is to devise a special class of microstructures—by means of an iterated homogenization procedure in finite elasticity together with an exact dilute result for sequential laminates—that allows to compute exactly the macroscopic response of the resulting fiber-reinforced materials. The proposed framework incorporates direct microstructural information up to the two-point correlation functions, and requires the solution to a Hamilton–Jacobi equation with the fiber concentration and the macroscopic deformation gradient playing the role of “time” and “spatial” variables, respectively. In addition to providing constitutive models for the macroscopic response of fiber-reinforced materials, the proposed theory also gives information about the local fields in the matrix and fibers, which can be used to study the evolution of microstructure and the development of instabilities. As a first application of the theory, closed-form results for the case of Neo-Hookean solids reinforced by a transversely isotropic distribution of anisotropic fibers are worked out. These include a novel explicit criterion for the onset of instabilities under general finite-strain loading conditions.     

Methodological fundamentals of reliable prediction of the durability of the materials of heat-and-power-engineering pipes up to 500,000 h

The article shows methodological possibilities of improving the results of the prediction of characteristics of the long-time strength of metallic materials by changing in the method of generalized diagrams the conditions of geometric similarity of the equivalent stresses and the time to rupture corresponding to them. This entails poorer reliability of the predicted characteristics, which, however, are still numerically lower than the analogous characteristics extrapolated by parametric temperature-time dependences of Larson—Miller type. Translated from Problemy Prochnosti, No. 1, pp. 79–85, January–February, 1997.     

Static and cyclic crack resistance of 22K-type steels

The data on the cyclic and static crack resistance of 22K-type steel used in large-diameter pipelines of nuclear power plants with RBMK-100 reactors are generalized. The data on the fatigue crack growth rate at 20 and 350°C for R = 0.1–0.7 and fracture toughness are presented. __________ Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 42, No. 4, pp. 54–58, July–August, 2006.     

Bayesian reliability analysis when multiple early failures may be present

Summary This paper discusses the Bayesian reliability analysis for an exponential failure model on the basis of some ordered observations when the firstp observations may represent “early failures” or “outliers”. The Bayes estimators of the mean life and reliability are obtained for the underlying parametric model referred to as theSB(p) model under the assumption of the squared error loss function, the inverted gamma prior for the scale parameter and a generalized uniform prior for the nuisance parameter.     

Ein Mitbegründer der modernen Medizin- und Wissenschaftsethik: John Gregory (1724–1773) und seineLectures on the Duties and Qualifications of a Physician

The scottish physician and philosopher John Gregory (1724–1773) published in 1770Lectures On The Duties and Qualifications Of A Physician. Besides giving many very concrete and pragmatic rules and proposals concerning medical etiquette and decency, like most medical “codifiers” did before and after him, Gregory also develops a truely “ethical”—in the sense of (moral-) philosophically based—“system of conduct in a physician”. His concept of practicing and teaching ethics in medicine and research combines Bacon's (1561–1626) philosophy of nature and science with both, the general moral philosophy of the religious sceptic David Hume (1711–1776) and the traditional christian-occidental virtues and deontologies upheld by the movement of the so-called “Common-Sense Philosophy”. By thus combinig conservative moral traditions with the modern enlightenment philosophy of empirism, Gregory's teachings establish ethics in medicine and science on a very broad compromise. It can be proved that his very comprehensiveLectures had—particularly via the famousCode of Medical Ethics of Thomas Percival (1740–1804)—a decisive influence on our contemporary concepts of bioethics.      

Regional development in South Korea: accounting for research area in centrality and networks

This paper provides a first-ever look at differences of centrality scores (i.e., networks) over time and across research specializations in Korea. This is a much needed development, given the variance which is effectively ignored when Science Citation Index (SCI) publications are aggregated. Three quantitative tests are provided—OLS, two sample t-tests, and unit-root tests—to establish the patterns of centrality scores across Korea over time. The unit-root test is particularly important, as it helps identify patterns of convergence in each region’s centrality scores. For all other geographic regions besides Seoul, Gyeonggi, and Daejeon, there appears to be little promise—at least in the immediate future—of being network hubs. For these top three regions, though, there is a pattern of convergence in three-quarters of all research specializations, which we attribute in part to policies in the mid- and late-1990s.     

Characteristics of creep rate during the steady-state and accelerated stages criteria for evaluating damage to heat-resistant steels and alloys

Substantiation is provided for adopting strain characteristics as criteria of the damage content of heatresistant steels and alloys during high-temperature creep. The inadequacy of creep characteristics determined in laboratory tests of standard specimens in tension —analogous to characteristics obtained from primary creep curves constructed during service by measuring changes in the diameter of unmachined surfaces and steam pipes under internal pressure and variations in wall thickness —makes it necessary to adopt the latter as the sole criteria for evaluating damage content and predicting residual service life. Translated from Problemy Prochnosti, No. 12, pp. 31–36, December, 1994.     

Inherent safety concepts in nuclear power reactors

Different inherent safety concepts being considered in fast and thermal reactors are presented after outlining the basic goals of nuclear reactor safety, the ‘defence in depth’ philosophy to achieve these goals and the characteristics affecting the safety of liquid metal fast breeder and light water reactors. The inherent safety potential of fast reactors with respect to different sizes and types of fuel is also discussed. Finally, the approach proposed for the Indian Prototype Fast Breeder Reactor (Pfbr), which is in the detailed design stage, is also presented.     

Forschungsarbeiten über Werkstoff und Festigkeit

Zusammenfassung Zusammenfassender bericht über 157 Werkstoff-und Festigkeitsfragen betreffende Abhandlungen der Sammlung „Forschungsarbeiten auf dem Gebiete des Ingenieurwesens”—Zur Elastizit?tstheorie—Die Eigenschaften der metallischen Werkstoffe—Verhalten bei statischer Beanspruchung: Elastizit?t und Festigkeit; die plastische Form?nderung; Festigkeit bei h?heren Temperaturen; Form und Festigkeit, Versuche an Probest?ben und an ganzen Maschinen-und Bauteilen—Verhalten bei dynamischer Beanspruchung: Schlagbenspruchung, Schwingungsbeanspruchung—Die H?rte—Sonstige Eigenschaften—Beton und Steine: Alterung, Elastizit?t und Festigkeit, Einflu? der Eisenbewehrungen; Quadern für Brückengelenke—Organische Werkstoffe: Holz, Treibriemen—Zusammenfassung und Schlu?bemerkung. Bei de Abfassung dieser Arbeit wurde ich von den Herren Dr.-Ing.H. Ude, Berlin, und Dr.-Ing.H. Holdt, Darmstadt, wesentlich unterstützt.