Academic literature on the topic 'Reduction property for counter-examples'
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Journal articles on the topic "Reduction property for counter-examples"
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Kim, Gang-Min, Jeong-Won Lee, Sung-Jun Lee, and Chang-Lae Kim. "Friction Property of Hierarchical Micro/Nanopatterned PDMS." Materials 15, no. 24 (December 7, 2022): 8736. http://dx.doi.org/10.3390/ma15248736.
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Polydimethylsiloxane (PDMS) has many advantages, but the friction coefficient generated by contact with the counter material is high. The purpose of this study is to reduce the friction coefficient by forming hierarchical micro/nanopatterns on the PDMS surface using the imprinting method. In addition, the optimum conditions for reducing the friction coefficient by controlling the sliding speed and normal load were determined. After contacting flat bare PDMS and hierarchical micro/nanostructured PDMS with a counter tip made of polyurethane (PU), the change in friction with sliding speed and vertical load was evaluated. Under normal load conditions, the average friction coefficient of the bare PDMS decreased as the sliding speed increased, and that of the patterned PDMS slightly increased. Regardless of the sliding speed, the friction coefficient decreased as the normal load increased for both specimens. At a sliding speed of 4 mm/s under a load of 10 mN, the friction reduction effect of the pattern structure was the largest at 79%. Overall, the greatest friction reduction effect (84%) was confirmed in patterned PDMS with the lowest friction coefficient under the conditions of 4 mm/s, 50 mN, compared to bare PDMS with the highest friction coefficient under the conditions of 4 mm/s, 10 mN.
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Dela Rosa, Lyka B., and Joel H. Jorolan. "Electrochemical Investigations on the NO-Releasing Property of Ruthenium Nitrosyl Complex." Asian Journal of Chemistry 35, no. 1 (December 27, 2022): 52–56. http://dx.doi.org/10.14233/ajchem.2023.24047.
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In this study, the NO-donating property of [Ru(BPG)Cl(NO)]Cl (BPG = N,N-bis(2- pyridylmethyl)glycinato anion) via electrochemical activation was assessed. The synthesized BPG and [Ru(BPG)Cl(NO)]Cl were characterized by UV-Vis and FT-IR spectroscopy. To determine if NO may be released from the compound via one-electron reduction, cyclic voltammetric experiments in aqueous and non-aqueous solutions were performed using a three-electrode cell consisting of glassy carbon working electrode, Pt wire counter electrode and Ag/AgCl or Ag/Ag+ reference electrode. The [Ru(BPG)Cl(NO)]Cl complex showed two one-electron reversible reductions in dimethylformamide, which suggests decreased ability as NO donor. In aqueous solution at pH 2.0, [Ru(BPG)Cl(NO)]Cl exhibited a one-electron irreversible reduction, which could be assigned to a Ru-NO centered reduction. The irreversibility of the reduction could be due to NO labilization and suggests that [Ru(BPG)Cl(NO)]Cl could be a potential NO donor in acidic aqueous medium.
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Thierry-Mieg, Yann. "Symbolic and Structural Model-Checking." Fundamenta Informaticae 183, no. 3-4 (January 10, 2022): 319–42. http://dx.doi.org/10.3233/fi-2021-2090.
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Brute-force model-checking consists in exhaustive exploration of the state-space of a Petri net, and meets the dreaded state-space explosion problem. In contrast, this paper shows how to solve model-checking problems using a combination of techniques that stay in complexity proportional to the size of the net structure rather than to the state-space size. We combine an SMT based over-approximation to prove that some behaviors are unfeasible, an under-approximation using memory-less sampling of runs to find witness traces or counter-examples, and a set of structural reduction rules that can simplify both the system and the property. This approach was able to win by a clear margin the model-checking contest 2020 for reachability queries as well as deadlock detection, thus demonstrating the practical effectiveness and general applicability of the system of rules presented in this paper.
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Seifert-Dähnn, Isabel. "Insurance engagement in flood risk reduction – examples from household and business insurance in developed countries." Natural Hazards and Earth System Sciences 18, no. 9 (September 14, 2018): 2409–29. http://dx.doi.org/10.5194/nhess-18-2409-2018.
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Abstract. Insurance can be an important mechanism to stimulate flood risk reduction and thus decrease losses. However, there is a gap between the theoretical potential described by academic scholars and the actual engagement of insurers. In the analysis, I have collected examples of insurers' engagement in flood risk reduction, focusing on household and business insurance in developed countries. Insurers engaged either directly, e.g., through co-financing risk reduction, or more indirectly by giving incentives to policyholders or governmental actors to adopt risk reduction measures. I analyzed their engagement with the framing conditions of the market they were acting in, such as market penetration or private or public insurance schemes. I found risk reduction measures like awareness-raising campaigns targeting citizens to be quite common across several countries. There was less insurance engagement in risk reduction measures such as warning or land-use planning, which are perceived to be mainly governmental tasks. The use of risk-based pricing as an incentive for the adoption of risk reduction measures as suggested by academia is difficult in practice, due to barriers such as information gaps on the effectiveness of property-level protection measures and requirements concerning the affordability of insurance. New approaches to overcome these shortfalls include organized data collection on property-level protection measures or the insurance of high-risks for affordable premiums in public–private partnership constellations with the government.
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DRAGOVIĆ, VLADIMIR, BORISLAV GAJIĆ, and BOŽIDAR JOVANOVIĆ. "SYSTEMS OF HESS–APPEL'ROT TYPE AND ZHUKOVSKII PROPERTY." International Journal of Geometric Methods in Modern Physics 06, no. 08 (December 2009): 1253–304. http://dx.doi.org/10.1142/s0219887809004211.
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We start with a review of a class of systems with invariant relations, so called systems of Hess–Appel'rot type that generalizes the classical Hess–Appel'rot rigid body case. The systems of Hess–Appel'rot type have remarkable property: there exists a pair of compatible Poisson structures, such that a system is certain Hamiltonian perturbation of an integrable bi-Hamiltonian system. The invariant relations are Casimir functions of the second structure. The systems of Hess–Appel'rot type carry an interesting combination of both integrable and non-integrable properties. Further, following integrable line, we study partial reductions and systems having what we call the Zhukovskii property: These are Hamiltonian systems on a symplectic manifold M with actions of two groups G and K; the systems are assumed to be K-invariant and to have invariant relation Φ = 0 given by the momentum mapping of the G-action, admitting two types of reductions, a reduction to the Poisson manifold P = M/K and a partial reduction to the symplectic manifold N0 = Φ-1(0)/G; final and crucial assumption is that the partially reduced system to N0 is completely integrable. We prove that the Zhukovskii property is a quite general characteristic of systems of Hess–Appel'rot type. The partial reduction neglects the most interesting and challenging part of the dynamics of the systems of Hess–Appel'rot type — the non-integrable part, some analysis of which may be seen as a reconstruction problem. We show that an integrable system, the magnetic pendulum on the oriented Grassmannian Gr+(n, 2) has a natural interpretation within Zhukovskii property and that it is equivalent to a partial reduction of certain system of Hess–Appel'rot type. We perform a classical and algebro-geometric integration of the system in dimension four, as an example of a known isoholomorphic system — the Lagrange bitop. The paper presents a lot of examples of systems of Hess–Appel'rot type, giving an additional argument in favor of further study of this class of systems.
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Chen, Huanyin. "Generalized Stable Rings and Regularity." Algebra Colloquium 19, no. 01 (March 2012): 159–68. http://dx.doi.org/10.1142/s1005386712000119.
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We prove in this article that the generalized stable property is invariant under Morita contexts. Further, we show that many classes of square matrices over generalized stable regular rings admit a diagonal reduction. Related examples are constructed as well.
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Cernea, Michael M. "IRR: An Operational Risks Reduction Model for Population Resettlement." Hydro Nepal: Journal of Water, Energy and Environment 1 (February 20, 2008): 35–39. http://dx.doi.org/10.3126/hn.v1i0.883.
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Abstract. The construction of hydropower dams and of other types of projects must plan also for the relocation of populations living in the project area, a process fraught with risks and difficulties. This paper describes an analytical, diagnostic, predictive, and planning tool for such projects, developed by the author, named the Impoverishment Risks and Reconstruction (IRR) model. Derived from knowledge and lessons of many previous projects, this model can serve as predictor of risks and problems that will be encountered in forthcoming projects, and be used as guide in applying strategies to counter, overcome or mitigate these risks. Among these are the eight basic risks of impoverishment faced during displacement and resettlement, such as: 1) Landlessness; 2) Joblessness; 3) Homelessness; 4) Marginalization; 5) Food insecurity; 6) Increased morbidity and mortality; 7) Loss of access to common property resources; and 8) Community Disarticulation. Further, the counter-risks strategies and measures are ‘modeled’, to help early risk-elimination or risk-reduction actions.
The IRR Model is being used internationally. It was applied also in studies for Nepal’s Kali Gandaki project to monitor implementation and impacts, to explore what measures and management strategies can be employed against the common risks in resettlement, and to assist those affected in overcoming land or house loss and in deriving benefits from the project.
Key words: Risk model, resettlement, displacement, impoverishment, reconstruction
Hydro Nepal: Journal of Water, Energy and Environment Vol. I, Issue No. 1 (2007) pp. 35-39
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Ji, Xiaohe, Cheng Yang, Wenjuan Fang, and Hua Zhang. "Insight into the reduction and property of graphene hydrogel for high efficiency composite counter electrodes and solar cells." Electrochimica Acta 297 (February 2019): 980–87. http://dx.doi.org/10.1016/j.electacta.2018.09.038.
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Chen, Yan, Xiao-Xiang He, Yang Yang, Heng-Yan Hu, Fu-Kang Li, and Lei Yang. "Dynamic RCS Reduction Performances of Antenna Array with Coding Metasurface." International Journal of Antennas and Propagation 2022 (March 14, 2022): 1–12. http://dx.doi.org/10.1155/2022/4644566.
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On the basis of combining the two concepts of digital coding metasurface and metasurface antenna, low radar cross-section (RCS) coding metasurface antenna array with dynamic scattering performances is presented in this paper. Extending scattering factor theory to coding metasurface antenna, by controlling the states of PIN diodes randomly, the scattering performances of coding metasurface antenna array can be tuned dynamically without degrading its radiation property. Based on phase cancellation principle, a 8 × 8 antenna array was finally simulated and fabricated. By comparing several different layouts, taking checkerboard layout, new chessboard layout, and “0101” square ring nested layout as examples, both monostatic and bistatic RCS of the antenna mentioned above can be reduced 10 dB or more in the frequency range of 9–10.5 GHz under the illumination of x-polarized incident wave. The measured data are consistent with the simulation data, which proves the effectiveness of the proposed method.
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Tamminen, Satu, Henna Tiensuu, Ilmari Juutilainen, and Juha Röning. "Steel Property and Process Models for Quality Control and Optimization." Materials Science Forum 762 (July 2013): 301–6. http://dx.doi.org/10.4028/www.scientific.net/msf.762.301.
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High quality and low variability in the properties of the products are the main goals in manufacturing. The quality of the product is verified by testing different properties. It can be improved with models developed for event prediction. This paper presents with application examples the modelling steps required for effective process modelling. First, the pre-processing and feature extraction phase are illustrated. The modelling phase concentrates especially on the heteroscedasticity problem that is commonly present in industrial applications. The process monitoring and control parameter optimization based on these models is presented, as well as the solution for the lack of observations for the dependent variable. Many of the developed models are in daily use in different process states in steel industry. They enable the design of new products and the analysis of the effects of different process parameters on variability reduction. The proposed methods are application independent.
Dissertations / Theses on the topic "Reduction property for counter-examples"
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Boskovitz, Agnes, and abvi@webone com au. "Data Editing and Logic: The covering set method from the perspective of logic." The Australian National University. Research School of Information Sciences and Engineering, 2008. http://thesis.anu.edu.au./public/adt-ANU20080314.163155.
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Errors in collections of data can cause significant problems when those data are used. Therefore the owners of data find themselves spending much time on data cleaning. This thesis is a theoretical work about one part of the broad subject of data cleaning - to be called the covering set method. More specifically, the covering set method deals with data records that have been assessed by the use of edits, which are rules that the data records are supposed to obey. The problem solved by the covering set method is the error localisation problem, which is the problem of determining the erroneous fields within data records that fail the edits. In this thesis I analyse the covering set method from the perspective of propositional logic. I demonstrate that the covering set method has strong parallels with well-known parts of propositional logic. The first aspect of the covering set method that I analyse is the edit generation function, which is the main function used in the covering set method. I demonstrate that the edit generation function can be formalised as a logical deduction function in propositional logic. I also demonstrate that the best-known edit generation function, written here as FH (standing for Fellegi-Holt), is essentially the same as propositional resolution deduction. Since there are many automated implementations of propositional resolution, the equivalence of FH with propositional resolution gives some hope that the covering set method might be implementable with automated logic tools. However, before any implementation, the other main aspect of the covering set method must also be formalised in terms of logic. This other aspect, to be called covering set correctibility, is the property that must be obeyed by the edit generation function if the covering set method is to successfully solve the error localisation problem. In this thesis I demonstrate that covering set correctibility is a strengthening of the well-known logical properties of soundness and refutation completeness. What is more, the proofs of the covering set correctibility of FH and of the soundness / completeness of resolution deduction have strong parallels: while the proof of soundness / completeness depends on the reduction property for counter-examples, the proof of covering set correctibility depends on the related lifting property. In this thesis I also use the lifting property to prove the covering set correctibility of the function defined by the Field Code Forest Algorithm. In so doing, I prove that the Field Code Forest Algorithm, whose correctness has been questioned, is indeed correct. The results about edit generation functions and covering set correctibility apply to both categorical edits (edits about discrete data) and arithmetic edits (edits expressible as linear inequalities). Thus this thesis gives the beginnings of a theoretical logical framework for error localisation, which might give new insights to the problem. In addition, the new insights will help develop new tools using automated logic tools. What is more, the strong parallels between the covering set method and aspects of logic are of aesthetic appeal.
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Boskovitz, Agnes. "Data Editing and Logic: The covering set method from the perspective of logic." Phd thesis, 2008. http://hdl.handle.net/1885/49318.
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Errors in collections of data can cause significant problems when those data are used. Therefore the owners of data find themselves spending much time on data cleaning. This thesis is a theoretical work about one part of the broad subject of data cleaning - to be called the covering set method. More specifically, the covering set method deals with data records that have been assessed by the use of edits, which are rules that the data records are supposed to obey. The problem solved by the covering set method is the error localisation problem, which is the problem of determining the erroneous fields within data records that fail the edits. In this thesis I analyse the covering set method from the perspective of propositional logic. ...
Book chapters on the topic "Reduction property for counter-examples"
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Iliopoulos, J., and T. N. Tomaras. "Scattering in Quantum Field Theory." In Elementary Particle Physics, 253–72. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780192844200.003.0012.
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We show that the use of the perturbation expansion around the free field Hamiltonian imposes severe constraints for the scattering formalism to be applicable. We present the physical assumptions which are necessary in order to define the asymptotic states and the scattering matrix in quantum field theory. A very important physical requirement is the property of short range for all interactions, which implies the absence of zero mass particles. We derive the reduction formula and obtain the Feynman rules for the scattering amplitude. We give examples of low order computations for the electron Compton scattering, the electron–positron annihilation into a muon pair and the decay of charged pions.
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J. Fos, Peter, Peggy A. Honoré, and Lt Gen. Russel L. Honoré. "Coordination of Public Health Response: The Role of Leadership in Responding to Public Health Emergencies." In Evidence-Based Approaches to Effectively Respond to Public Health Emergencies [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.96304.
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Public health emergencies are becoming more commonplace every year. Naturally occurring public health emergencies, such as hurricanes, typhoons, tsunamis, and floods cause significant devastation to property and people. Although these emergencies are becoming more and more common, response is still very challenging. A root cause of failed response is a lack of coordination between national, regional, and local public health agencies. These failed and unsuccessful responses are seen with naturally occurring public health emergencies, including pandemics. This chapter addresses coordination, its barriers and challenges, with a focus on the role of leadership in response to public health emergencies. Coordination leadership is a critical aspect of successful and effective response to emergencies. Leadership styles will be discussed and examples of effective leadership. Lessons learned will be presented, as well as research findings. Examples discussed include Hurricane Katrina, the tsunami of 2004 in Thailand, the COVID-19 pandemic, and the Sendai Framework for Disaster Risk Reduction, Sustainable Development Goals.
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Jamroga, Wojciech, Beata Konikowska, Damian Kurpiewski, and Wojciech Penczek. "Multi-valued Verification of Strategic Ability." In A Mosaic of Computational Topics: from Classical to Novel. IOS Press, 2020. http://dx.doi.org/10.3233/stal200013.
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Some multi-agent scenarios call for the possibility of evaluating specifications in a richer domain of truth values. Examples include runtime monitoring of a temporal property over a growing prefix of an infinite path, inconsistency analysis in distributed databases, and verification methods that use incomplete anytime algorithms, such as bounded model checking. In this paper, we present multi-valued alternating-time temporal logic (mv-ATL*→), an expressive logic to specify strategic abilities in multi-agent systems. It is well known that, for branching-time logics, a general method for model-independent translation from multi-valued to two-valued model checking exists. We show that the method cannot be directly extended to mv-ATL*→. We also propose two ways of overcoming the problem. Firstly, we identify constraints on formulas for which the model-independent translation can be suitably adapted. Secondly, we present a model-dependent reduction that can be applied to all formulas of mv-ATL*→. We show that, in all cases, the complexity of verification increases only linearly when new truth values are added to the evaluation domain. We also consider several examples that show possible applications of mv-ATL*→ and motivate its use for model checking multi-agent systems.
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Zinn-Justin, Jean. "Quantum field theory (QFT) at finite temperature: Equilibrium properties." In Quantum Field Theory and Critical Phenomena, 786–830. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198834625.003.0033.
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Some equilibrium properties in statistical quantum field theory (QFT), that is, relativistic QFT at finite temperature are reviewed. Study of QFT at finite temperature is motivated by cosmological problems, high energy heavy ion collisions, and speculations about possible phase transitions, also searched for in numerical simulations. In particular, the situation of finite temperature phase transitions, or the limit of high temperature (an ultra-relativistic limit where the temperature is much larger than the physical masses of particles) are discussed. The concept of dimensional reduction emerges, in many cases, statistical properties of finite-temperature QFT in (1, d − 1) dimensions can be described by an effective classical statistical field theory in (d − 1) dimensions. Dimensional reduction generalizes a property already observed in the non-relativistic example of the Bose gas, and indicates that quantum effects are less important at high temperature. The corresponding technical tools are a mode-expansion of fields in the Euclidean time variable, singling out the zero modes of boson fields, followed by a local expansion of the resulting (d − 1)-dimensional effective field theory (EFT). Additional physical intuition about QFT at finite temperature in (1, d−1) dimensions can be gained by considering it as a classical statistical field theory in d dimensions, with finite size in one dimension. This identification makes an analysis of finite temperature QFT in terms of the renormalization group (RG), and the theory of finite-size effects of the classical theory, possible. These ideas are illustrated with several simple examples, the φ4 field theory, the non-linear σ-model, the Gross–Neveu model and some gauge theories.
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Dyall, Kenneth G., and Knut Faegri. "Molecular Properties." In Introduction to Relativistic Quantum Chemistry. Oxford University Press, 2007. http://dx.doi.org/10.1093/oso/9780195140866.003.0019.
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Strictly speaking, in quantum mechanics a measurable property is defined as an observable connected to a self-adjoint operator. However, in common usage the term molecular property is loosely taken to mean any physical attribute of a molecule, preferably amenable to experimental measurement. Common examples of properties of interest to chemists are molecular structure, thermodynamic quantities, spectroscopic transition energies and intensities, and various electric and magnetic moments. The amenability to experiment may exist only in principle—one of the strong points of modern computational chemistry is the possibility of studying phenomena occurring under conditions that lie beyond the present experimental capabilities. Sometimes, differential effects between different theoretical models are also regarded as properties: thus the correlation energy is generally considered to be the difference between the Hartree–Fock energy and the energy obtained from a complete many-electron treatment (e.g. full CI or MBPT to all orders). At best only the latter of these is accessible to experiment. Similarly, certain relativistic effects (e.g. bond contraction) only appear as the difference between results from a relativistic and a nonrelativistic calculation. The calculation of molecular properties in a relativistic framework follows the same principles as for the nonrelativistic case once a wave function or electron density of adequate quality is available. Our aim here is therefore not to provide explicit expressions and formulas for the calculation of a more or less complete catalog of properties. However, in relativistic calculations of molecular properties there are some aspects of the theory that warrant special care and consideration. In particular, we need to know how to handle features such as Lorentz invariance, gauge invariance, and negativeenergy states. Moreover, the electric and magnetic fields appear as natural parts of the relativistic Hamiltonian, and we therefore expect that properties involving these may require a different treatment from the nonrelativistic case where terms involving external fields are grafted onto the nonrelativistic Hamiltonian, often based on some reduction or approximation from the relativistic case.
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Hussein Mekni, Nejib Ben, and Noureddine Raouafi. "Coordination, Degrading Agent, Catalyst Property and Spectroscopy of Organocalcium Compounds." In The Synthetic Methods, Structures, and Properties of the Ca-Cσ Bond Organocalcium Containing Compounds, 56–82. BENTHAM SCIENCE PUBLISHERS, 2022. http://dx.doi.org/10.2174/9789815040647122010006.
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In addition to the coordination of the calcium to the n electron pairs, some examples of coordination to the π electron pairs are observed resulting from calcium interactions with highly conjugated systems. The complex structures vary from ordinary to close to the unexpected organocalcium inverse sandwich. The organocalcium Ca-C bond containing compounds are highly reactive. They degrade and act as degrading agents on the solvent. The study of the effect of five factors: temperature, concentration, organic group, counter ion and coordinated donor solvent, shows an intramolecular degradation mechanism. Organocalcium complexes are more stable in the THP than in the THF ethereal media. Calcium and organocalcium Ca-Cσ-bond containing derivatives are described as efficient pre-catalysts for catalytic conversions of alkenes by polymerization, hydroamination, hydrosilylation, hydrogenation, and hydrophosphination. The activation process is suggested as an electrostatic interaction between the alkene and Lewis acidic calcium metallic species, leading to both vertical and horizontal polarization of the π bond electron density, resulting in an incentive for nucleophilic attack. Some researchers illustrate that the organocalcium derivatives may be described as “Trojan horses” X-ray constitutes the most efficient technique to characterize the organocalcium structures for crystalized compounds, affording interesting information about angle values and bond lengths. The 43Ca, 13C and 1H NMR spectroscopy constitutes an alternative, secondary and complementary tool for characterizing both soluble, and even insoluble compounds, monitoring the reaction progress and making specific experimental manipulations. The coupling constants 1 JCa-C, and 2 JCa-C-H are not mentioned and there is no mass spectrometry nor IR spectroscopy studies
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Tiwari, Sandip. "Quantum confinement and monolayer semiconductors." In Semiconductor Physics, 649–98. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780198759867.003.0020.
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This chapter brings together several themes and perspectives by exploring them in quantum-confined conditions or in monolayer crystals. In it, confinement of electrons and holes at heterostructure interfaces, in inversion layers, in quantum wells and in superlattices is analyzed using the envelope function to illustrate the variety of interactions that must be properly accounted for. The formation of subbands in confinement, minibands in superlattices, and transmission, reflection and resonance at confined barriers and wells is discussed. Propagation, screening, scattering and the behavior of shallow dopants are discussed to illustrate changes with reduction of dimensions. Particular emphasis is placed on optical transitions to illustrate the changes in selection rules for interband and intraband transitions. Confined semiconductors are contrasted with monolayer semiconductors, using graphene and nanotubes as examples whose analysis and electronic properties are discussed, to compare them with the semiconductor discussions in earlier chapters.
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Bricocoli, Massimo, and Angelo Salento. "Housing and the grounded city: Rent extraction and social innovations." In The Foundational Economy and Citizenship, 129–56. Policy Press, 2020. http://dx.doi.org/10.1332/policypress/9781447353355.003.0007.
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This chapter questions the contemporary forms of civil society engagement with housing, starting from the assumption that the concrete importance of specific initiatives of social innovation should be assessed in relation to existing problems. Since the basis of housing problems is not only the decline of public housing policies, but the increasing strength of rent extraction on urban land, the contributions from communities and the civil society should be assessed on their ability to counter the extraction of unearned rents from urban land. Referring mainly to Italian cases, the chapter shows that many experiments tackle some symptoms or side effects of this trend while some alleged social innovations are even an integral part of the problem. However, some experiments can be considered as examples of a radical progressive vision on housing, as they switch from the idea of property to one of access, and prevent the capture of urban land value.
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Ma, Wenlin, Jian Shang, Jinjun Lu, and Junhu Meng. "Material and Tribology Issues of Self-Lubricating Copper Matrix Composite." In Processing Techniques and Tribological Behavior of Composite Materials, 47–71. IGI Global, 2015. http://dx.doi.org/10.4018/978-1-4666-7530-8.ch002.
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This chapter addresses fundamental issues (i.e. material issue and tribology issue) of the self-lubricating copper matrix composite under dry sliding contact. The development of metal matrix composites for tribological applications relies largely on a trial-and-error method because no adequate knowledge from tribology is involved. To make good metal matrix composites for tribological applications, knowledge from both materials science and tribology are required. This chapter comprehensively introduces the tribological aspect of self-lubricating copper matrix composites for tribological applications. The main mission of this chapter is to introduce the tribological consideration in fabricating copper matrix composite (Cu- graphite and Cu-SiO2 composites as examples) for tribological application. Material aspect (e.g. mixing method, sintering temperature) is briefly reviewed. The main concern is variations of chemical composition, microstructure, and property of tribo-layer of copper matrix composites sliding against different counter-face materials and under different operating conditions.
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Ma, Wenlin, Jian Shang, Jinjun Lu, and Junhu Meng. "Material and Tribology Issues of Self-Lubricating Copper Matrix Composite." In Materials Science and Engineering, 414–38. IGI Global, 2017. http://dx.doi.org/10.4018/978-1-5225-1798-6.ch017.
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This chapter addresses fundamental issues (i.e. material issue and tribology issue) of the self-lubricating copper matrix composite under dry sliding contact. The development of metal matrix composites for tribological applications relies largely on a trial-and-error method because no adequate knowledge from tribology is involved. To make good metal matrix composites for tribological applications, knowledge from both materials science and tribology are required. This chapter comprehensively introduces the tribological aspect of self-lubricating copper matrix composites for tribological applications. The main mission of this chapter is to introduce the tribological consideration in fabricating copper matrix composite (Cu- graphite and Cu-SiO2 composites as examples) for tribological application. Material aspect (e.g. mixing method, sintering temperature) is briefly reviewed. The main concern is variations of chemical composition, microstructure, and property of tribo-layer of copper matrix composites sliding against different counter-face materials and under different operating conditions.
Conference papers on the topic "Reduction property for counter-examples"
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Lowe, T. W., M. I. G. Bloor, and M. J. Wilson. "Functionality in Surface Design." In ASME 1990 Design Technical Conferences. American Society of Mechanical Engineers, 1990. http://dx.doi.org/10.1115/detc1990-0006.
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Abstract The partial differential equation (PDE) method is used to generate surfaces which can be completely described using few parameters all of which have a global influence on the surface shape. We show how this method is suitable for the design of surfaces which optimize some property of the surface subject to certain given design restrictions. This is illustrated by considering two examples: the design of a yacht and the reduction of stress in a loaded blend.
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Bochot, Thomas, Pierre Virelizier, Helene Waeselynck, and Virginie Wiels. "Paths to Property Violation: A Structural Approach for Analyzing Counter-Examples." In 2010 IEEE 12th International Symposium on High-Assurance Systems Engineering (HASE). IEEE, 2010. http://dx.doi.org/10.1109/hase.2010.15.
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Lee, In, Il-Kwon Oh, and Dong-Min Lee. "Vibration and Flutter Analysis of Stiffened Composite Plate Considering Thermal Effect." In ASME 1997 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/imece1997-0716.
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Abstract Vibration and flutter analyses have been performed for stiffened composite laminated plates considering thermal effect. The FSDT (First order Shear Deformable plate Theory) and Timoshenko beam theory are used for the finite element modeling of a skin panel and stiffeners, respectively. The von Karman nonlinear strain-displacement relation is adopted to consider a large deflection due to the thermal buckling loads and severe aerodynamic loads. The first order piston theory is used for the modeling of aerodynamic loads. The temperature distribution is assumed to be constant over the surface and has a thermal gradient through the thickness of the plate. It is assumed that a degradation of the elastic properties of the constituent materials is a function of the temperature field itself. Guyan reduction method is employed to reduce the problem size and computational time. Newton-Rhapson iteration method is used to obtain the postbuckled deflection. Complex eigenvalue solver with LUM/NTF approximation method is used to obtain vibration and flutter characteristics. The effects of various parameters, such as ply orientation, temperature gradient, material property degradation and the stiffening scheme on flutter characteristics are investigated through some numerical examples. The degradation of material properties affects the aero-thermo-postbuckled deflection, vibration characteristics and flutter boundary. The selection of proper stiffening scheme results in great improvements of flutter characteristics of laminated panels without introducing considerable weight penalty.
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Malik, Arif, John Wendel, Mark Zipf, and Andrew Nelson. "A Reliability-Based Approach to Flatness Actuator Effectiveness in 20-High Rolling Mills." In ASME 2012 International Manufacturing Science and Engineering Conference collocated with the 40th North American Manufacturing Research Conference and in participation with the International Conference on Tribology Materials and Processing. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/msec2012-7281.
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20-High rolling mills process high strength and/or very thin non-ferrous and ferrous metals using a complex, cluster arrangement of rolls. The 20-high roll cluster arrangement achieves specific flatness goals in the thin sheet by delivering maximum rolling pressure while minimizing the deflections of the small diameter rolls. 20-high mills also employ flatness control mechanisms with sophisticated actuators, such as those to shift intermediate rolls and deflect backup bearing shafts. The purpose of this is to compensate for variations in strip dimensional and mechanical properties which can cause poor flatness control quality from discrepancies in work-roll gap profile and distribution of rolling force. This suggests that the random property differences in the rolling parameters that substantially affect the flatness must be directly accounted for in flatness control algorithms in order to achieve strict flatness quality. The use of accurate mathematical models that account for the rolling pass target gage reduction can optimize the flatness control actuators and help gain an advantage in the thin gauge strip competitive global market. Based on the expected process parameter variations and nominal mill set-points (speed, tension, gage reduction, etc.), the mill’s process control computer should determine the probability that target flatness control quality will be met for a required length of strip. The process computer should then either modify the number of rolling passes or adjust the thickness reduction schedule before rolling begins to secure an improved flatness probability estimate if the probability of achieving target strip flatness is too low for the required deliverable quality. Therefore, this research integrates 1) 20-high roll-stack mill mathematical modeling, 2) probability distribution data for random important rolling parameters, 3) reliability-based models to predict the probability of achieving desired strip flatness, and 4) optimization examples. The results can be used to reduce wasted rolled metal from poor flatness before rolling.
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Leblond, Marc, and Clément M. Gosselin. "Static Balancing of Spatial and Planar Parallel Manipulators With Prismatic Actuators." In ASME 1998 Design Engineering Technical Conferences. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/detc98/mech-5963.
Full textAbstract:
Abstract In this paper, the static balancing of existing spatial and planar parallel manipulators by the addition of balancing elements is addressed. Static balancing is defined here as the set of conditions on manipulator dimensional and inertial parameters which, when satisfied, ensure that the weight of the links does not produce any force (or torque) at the actuators for any configuration of the manipulator, under static conditions. These conditions are derived here for spatial six-degree-of-freedom parallel manipulators and it is shown that planar three-degree-of-freedom parallel manipulators can be treated as a particular case of the spatial 6-dof mechanisms. The static balancing conditions associated with planar mechanisms can therefore easily be found, but are not given here because of space limitations. A brief geometric interpretation of the balancing conditions which are associated with statically balanced spatial mechanisms is then carried out. It is shown that balancing is generally possible even when the dimensional parameters are imposed, which is a useful property since dimensional parameters are usually obtained from kinematic design or optimization. Finally, examples of balanced planar and spatial parallel manipulators are given. Static balancing leads to considerable reduction in the actuator forces (or torques), which in turn leads to less powerful actuators and more efficient designs. Moreover, the possibility of balancing existing systems by introducing additional elements, as demonstrated here, is of interest for retrofitting existing parallel mechanisms.
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Yu, Yang, Changchun Wu, Xiaokai Xing, and Lili Zuo. "Energy Saving for a Chinese Crude Oil Pipeline." In ASME 2014 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/pvp2014-28034.
Full textAbstract:
The Dongying-Linyi Crude Oil Pipeline, transporting the crude oil from Shengli Oilfield to the outside, is one of the most important pipelines in East China. It is of great significance for saving energy, reducing emissions and improving the economy by optimizing pipeline operation. By analyzing the daily operation reports and monthly energy consumption reports, the energy consumption situation of the pipeline is revealed. Then the crude oil from Shengli Oilfield is collected, and its physical property is tested and researched. Based on the topological structure, the technological process and the operation philosophy of the pipeline, the mathematical models for the optimal operation and the energy consumption are built and the corresponding algorithm is introduced. With the models and the algorithms mentioned above, a computer software is developed for the operation simulation and optimization of the pipeline. Combining with practice, three energy-saving measures for the pipeline are analyzed, including reduction of oil heating temperature, operation matching with peak-valley electricity price and operation matching with the combination of flow rates in a planned operation period. In addition, these energy-saving measures are evaluated by the software with several examples. It turns out that: the first measure can considerably reduce the energy consumption and the energy consumption cost of the pipeline; the second could reduce the energy consumption cost of the pipeline a lot, while may make the energy consumption go higher a little; the third could slightly lower the equivalent energy consumption and the energy cost at the same time, but the effect of it is not obvious.
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Van Durme, Robert E. "Spray Technology is Critical in Helping a Plant Achieve Optimal Performance." In ASME 2009 Power Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/power2009-81054.
Full textAbstract:
Spray nozzles are used in several locations inside a powerplant and have intimate contact with the processes in the plant. Nozzles are used for inlet fogging, humidification, Wet and Semi-Dry FGD (Flue Gas Desulphurization) applications using open spray towers, CFB (Circulating Fluidized Bed) and SDA (Spray Dry Absorber) scrubbers, NOx using SCR (Selective Catalytic Reduction) and SNCR (Selective Non-catalytic Reduction) technologies. As plants try to achieve optimum efficiency, spray nozzles need to be designed, installed, and maintained properly. In addition, operators and designers need to be aware when a spray nozzle needs to be cleaned or replaced. A defective spray nozzle will have an adverse affect on plant performance. Several factors are to be considered in selecting the proper nozzle. These include material of construction, flowrate, spray angle, operating pressure, placement, droplet size, maximum free passage, spray angle, and many more. New developments in spray nozzle technology are allowing powerplants to have better control and achieve/maintain the tighter regulations on key emissions in the plants. Examples of nozzle type, their application, and recent installations/retrofits will be discussed.
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Zhang, Yichi, and Bingen Yang. "Model Reduction for Mid-Frequency Transient Vibration Analysis of Beam Structures by the Augmented DTFM." In ASME 2021 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/imece2021-69979.
Full textAbstract:
Abstract Mid-frequency transient vibration analysis of flexible structures plays an important role in a variety of engineering applications. In a mid-frequency region, neither low-frequency methods like the finite element analysis (FEA) nor high-frequency methods like the statistical energy analysis (SEA) are directly applicable to transient vibration analysis. For optimal design of multi-body structures, a mid-frequency transient vibration analysis tool with a good balance of accuracy and efficiency in computation is in demand. In this paper, to address the aforementioned issue, a model reduction method is developed for mid-frequency transient vibration analysis of beam structures. The method is based on the augmented distributed transfer function method (augmented DTFM). In this work, the augmented DTFM is modified for model reduction in mid-frequency analysis of beam structures, which is an extension of the authors’ previous effort. The idea behind this approach is to properly select several modes in the low-frequency region and a number of modes in a mid-frequency region that encompasses the excitation frequency spectrum, from the infinite series given by the augmented DTFM. This way, a reduced model of a beam structure for mid-frequency transient analysis is systematically obtained. The proposed model reduction method is validated in numerical examples, where the augmented method is compared with other methods, including the FEA. The accuracy and efficiency of the new method on the computation of transient displacement and shear force is demonstrated. As shown in the simulation results, a proper balance between accuracy and efficiency in model reduction can be achieved by the augmented DTFM. The computation savings by the proposed method, compared with the traditional numerical methods, can be of several orders of magnitude.
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Hendricks, Eric S. "Development of an Open Rotor Cycle Model in NPSS Using a Multi-Design Point Approach." In ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/gt2011-46694.
Full textAbstract:
NASA’s Environmentally Responsible Aviation Project and Subsonic Fixed Wing Project are focused on developing concepts and technologies which may enable dramatic reductions to the environmental impact of future generation subsonic aircraft [1][2]. The open rotor concept (also referred to as the Unducted Fan or advanced turboprop) may allow the achievement of this objective by reducing engine emissions and fuel consumption. To evaluate its potential impact, an open rotor cycle modeling capability is needed. This paper presents the initial development of an open rotor cycle model in the Numerical Propulsion System Simulation (NPSS) computer program which can then be used to evaluate the potential benefit of this engine. The development of this open rotor model necessitated addressing two modeling needs within NPSS. First, a method for evaluating the performance of counter-rotating propellers was needed. Therefore, a new counter-rotating propeller NPSS component was created. This component uses propeller performance maps developed from historic counter-rotating propeller experiments to determine the thrust delivered and power required. Second, several methods for modeling a counter-rotating power turbine within NPSS were explored. These techniques used several combinations of turbine components within NPSS to provide the necessary power to the propellers. Ultimately, a single turbine component with a conventional turbine map was selected. Using these modeling enhancements, an open rotor cycle model was developed in NPSS using a multi-design point approach. The multi-design point (MDP) approach improves the engine cycle analysis process by making it easier to properly size the engine to meet a variety of thrust targets throughout the flight envelope. A number of design points are considered including an aerodynamic design point, sea-level static, takeoff and top of climb. The development of this MDP model was also enabled by the selection of a simple power management scheme which schedules propeller blade angles with the freestream Mach number. Finally, sample open rotor performance results and areas for further model improvements are presented.
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Xu, Xiaoqiang, Shikui Chen, Xianfeng David Gu, and Michael Yu Wang. "Conformal Topology Optimization of Heat Conduction Problems on Manifolds Using an Extended Level Set Method (X-LSM)." In ASME 2021 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/detc2021-67819.
Full textAbstract:
Abstract In this paper, the authors propose a new dimension reduction method for level-set-based topology optimization of conforming thermal structures on free-form surfaces. Both the Hamilton-Jacobi equation and the Laplace equation, which are the two governing PDEs for boundary evolution and thermal conduction, are transformed from the 3D manifold to the 2D rectangular domain using conformal parameterization. The new method can significantly simplify the computation of topology optimization on a manifold without loss of accuracy. This is achieved due to the fact that the covariant derivatives on the manifold can be represented by the Euclidean gradient operators multiplied by a scalar with the conformal mapping. The original governing equations defined on the 3D manifold can now be properly modified and solved on a 2D domain. The objective function, constraint, and velocity field are also equivalently computed with the FEA on the 2D parameter domain with the properly modified form. In this sense, we are solving a 3D topology optimization problem equivalently on the 2D parameter domain. This reduction in dimension can greatly reduce the computing cost and complexity of the algorithm. The proposed concept is proved through two examples of heat conduction on manifolds.