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Zhu, He, Stephen Magill i Suresh Jagannathan. "A data-driven CHC solver". ACM SIGPLAN Notices 53, nr 4 (2.12.2018): 707–21. http://dx.doi.org/10.1145/3296979.3192416.
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DE ANGELIS, EMANUELE, FABIO FIORAVANTI, ALBERTO PETTOROSSI i MAURIZIO PROIETTI. "Solving Horn Clauses on Inductive Data Types Without Induction". Theory and Practice of Logic Programming 18, nr 3-4 (lipiec 2018): 452–69. http://dx.doi.org/10.1017/s1471068418000157.
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AbstractWe address the problem of verifying the satisfiability of Constrained Horn Clauses (CHCs) based on theories of inductively defined data structures, such as lists and trees. We propose a transformation technique whose objective is the removal of these data structures from CHCs, hence reducing their satisfiability to a satisfiability problem for CHCs on integers and booleans. We propose a transformation algorithm and identify a class of clauses where it always succeeds. We also consider an extension of that algorithm, which combines clause transformation with reasoning on integer constraints. Via an experimental evaluation we show that our technique greatly improves the effectiveness of applying the Z3 solver to CHCs. We also show that our verification technique based on CHC transformation followed by CHC solving, is competitive with respect to CHC solvers extended with induction.
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Faella, Marco, i Gennaro Parlato. "Reachability Games Modulo Theories with a Bounded Safety Player". Proceedings of the AAAI Conference on Artificial Intelligence 37, nr 5 (26.06.2023): 6330–37. http://dx.doi.org/10.1609/aaai.v37i5.25779.
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Solving reachability games is a fundamental problem for the analysis, verification, and synthesis of reactive systems. We consider logical reachability games modulo theories (in short, GMTs), i.e., infinite-state games whose rules are defined by logical formulas over a multi-sorted first-order theory. Our games have an asymmetric constraint: the safety player has at most k possible moves from each game configuration, whereas the reachability player has no such limitation. Even though determining the winner of such a GMT is undecidable, it can be reduced to the well-studied problem of checking the satisfiability of a system of constrained Horn clauses (CHCs), for which many off-the-shelf solvers have been developed. Winning strategies for GMTs can also be computed by resorting to suitable CHC queries. We demonstrate that GMTs can model various relevant real-world games, and that our approach can effectively solve several problems from different domains, using Z3 as the backend CHC solver.
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Mordvinov, Dmitry A. "Property-Directed Inference of Relational Invariants". Modeling and Analysis of Information Systems 26, nr 4 (27.12.2019): 550–71. http://dx.doi.org/10.18255/1818-1015-2019-4-550-571.
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Property Directed Reachability (PDR) is an efficient and scalable approach to solving systems of symbolic constraints also known as Constrained Horn Clauses (CHC). In the case of non-linear CHCs, which may arise, e.g., from relational verification tasks, PDR aims to infer an inductive invariant for each uninterpreted predicate. However, in many practical cases this reasoning is not successful, as invariants should be derived for groups of predicates instead of individual predicates. The article describes a novel algorithm that identifies these groups automatically and complements the existing PDR technique. The key feature of the algorithm is that it does not require a possibly expensive synchronization transformation over the system of CHCs. We have implemented the algorithm on top of a up-to-date CHC solver Spacer. Our experimental evaluation shows that for some CHC systems, on which existing solvers diverge, our tool is able to discover relational invariants.
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Gheorghiu, Călin-Ioan. "Chebfun Solutions to a Class of 1D Singular and Nonlinear Boundary Value Problems". Computation 10, nr 7 (8.07.2022): 116. http://dx.doi.org/10.3390/computation10070116.
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The Chebyshev collocation method implemented in Chebfun is used in order to solve a class of second order one-dimensional singular and genuinely nonlinear boundary value problems. Efforts to solve these problems with conventional ChC have generally failed, and the outcomes obtained by finite differences or finite elements are seldom satisfactory. We try to fix this situation using the new Chebfun programming environment. However, for tough problems, we have to loosen the default Chebfun tolerance in Newton’s solver as the ChC runs into trouble with ill-conditioning of the spectral differentiation matrices. Although in such cases the convergence is not quadratic, the Newton updates decrease monotonically. This fact, along with the decreasing behaviour of Chebyshev coefficients of solutions, suggests that the outcomes are trustworthy, i.e., the collocation method has exponential (geometric) rate of convergence or at least an algebraic rate. We consider first a set of problems that have exact solutions or prime integrals and then another set of benchmark problems that do not possess these properties. Actually, for each test problem carried out we have determined how the Chebfun solution converges, its length, the accuracy of the Newton method and especially how well the numerical results overlap with the analytical ones (existence and uniqueness).
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DE ANGELIS, EMANUELE, FABIO FIORAVANTI, ALBERTO PETTOROSSI i MAURIZIO PROIETTI. "Predicate Pairing for program verification". Theory and Practice of Logic Programming 18, nr 2 (4.12.2017): 126–66. http://dx.doi.org/10.1017/s1471068417000497.
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AbstractIt is well-known that the verification of partial correctness properties of imperative programs can be reduced to the satisfiability problem for constrained Horn clauses (CHCs). However, state-of-the-art solvers for constrained Horn clauses (or CHC solvers) based onpredicate abstractionare sometimes unable to verify satisfiability because they look for models that are definable in a given class 𝓐 of constraints, called 𝓐-definable models. We introduce a transformation technique, calledPredicate Pairing, which is able, in many interesting cases, to transform a set of clauses into an equisatisfiable set whose satisfiability can be proved by finding an 𝓐-definable model, and hence can be effectively verified by a state-of-the-art CHC solver. In particular, we prove that, under very general conditions on 𝓐, the unfold/fold transformation rules preserve the existence of an 𝓐-definable model, that is, if the original clauses have an 𝓐-definable model, then the transformed clauses have an 𝓐-definable model. The converse does not hold in general, and we provide suitable conditions under which the transformed clauses have an 𝓐-definable modelif and only ifthe original ones have an 𝓐-definable model. Then, we present a strategy, called Predicate Pairing, which guides the application of the transformation rules with the objective of deriving a set of clauses whose satisfiability problem can be solved by looking for 𝓐-definable models. The Predicate Pairing (PP) strategy introduces a new predicate defined by the conjunction of two predicates occurring in the original set of clauses, together with a conjunction of constraints. We will show through some examples that an 𝓐-definable model may exist for the new predicate even if it does not exist for its defining atomic conjuncts. We will also present some case studies showing that Predicate Pairing plays a crucial role in the verification ofrelational properties of programs, that is, properties relating two programs (such as program equivalence) or two executions of the same program (such as non-interference). Finally, we perform an experimental evaluation of the proposed techniques to assess the effectiveness of Predicate Pairing in increasing the power of CHC solving.
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Sun, Jintao, Qi Chen, Baoming Zhao, Caohui Guo, Jianyu Liu, Mingming Zhang i Decai Li. "Temperature-dependent ion chemistry in nanosecond discharge plasma-assisted CH4 oxidation". Journal of Physics D: Applied Physics 55, nr 13 (4.01.2022): 135203. http://dx.doi.org/10.1088/1361-6463/ac45ac.
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Abstract Ion chemistry with temperature evolution in weakly ionized plasma is important in plasma-assisted combustion and plasma-assisted catalysis, fuel reforming, and material synthesis due to its contribution to plasma generation and state transition. In this study, the kinetic roles of ionic reactions in nanosecond discharge (NSD) plasma-assisted temperature-dependent decomposition and oxidation of methane are investigated by integrated studies of experimental measurements and mathematical simulations. A detailed plasma chemistry mechanism governing the decomposition and oxidation processes in a He/CH4/O2 combustible mixture is proposed and studied by including a set of electron impact reactions, reactions involving excited species, and ionic reactions. A zero-dimensional model incorporating the plasma kinetics solver ZDPlasKin and the combustion chemical kinetics solver CHEMKIN is used to calculate the time and temperature evolution of the ion density. Uncertainty analysis of ionic reactions on key species generation is conducted by using different referenced data, and insignificant sensitivity is found. The numerical model is consistent with experimental data for methane consumption and generation of major species including CO, CO2, and H2. By modeling the temporal evolution of key ions, it is observed that O2 + presents the largest concentration in the discharge stage, followed by CH4 +, CH3 +, and CH2 +, which is in accordance with the traditional ion chemistry in hydrocarbon flames and agrees well with molecular-beam mass spectrometer investigations. The path flux shows that the concentrations of key species, including electrons, O, OH, H, O(1D), O2(a1Δg), O2 +, CH3 +, and CH4 +, change within 1–2 orders of magnitude and that the transition from a homogeneous state to a contracted/constricted state does not occur. The path flux and sensitivity analysis reveal the significant roles of cations in the stimulation of active radical generation, including CH, O, OH, and O(1D), thus accelerating methane oxidation. This work provides a deep insight into the ion chemistry of temperature-dependent plasma-assisted CH4 oxidation.
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Zhou, Wenjun, Xi Qin, Ming Lv, Lifeng Qiu, Zhongjiang Chen i Fan Zhang. "Design of Plasmonic Photonic Crystal Fiber for Highly Sensitive Magnetic Field and Temperature Simultaneous Measurement". Micromachines 14, nr 9 (29.08.2023): 1684. http://dx.doi.org/10.3390/mi14091684.
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A high-sensitivity plasmonic photonic crystal fiber (PCF) sensor is designed and a metal thin film is embedded for achieving surface plasmon resonance (SPR), which can detect the magnetic field and temperature simultaneously. Within the plasmonic PCF sensor, the SPR sensing is accomplished by coating both the upper sensing channel (Ch1) and the lower sensing channel (Ch2) with gold film. In addition, the temperature-sensitive medium polydimethylsiloxane (PDMS) is chosen to fill in Ch1, allowing the sensor to respond to the temperature. The magnetic field-sensitive medium magnetic fluid (MF) is chosen to fill in Ch2, allowing this sensor to respond to the magnetic field. During these processes, this proposed SPR-PCF sensor can achieve dual-parameter sensing. The paper also investigates the electrical field characteristics, structural parameters and sensing performance using COMSOL. Finally, under the magnetic field range of 50–130 Oe, this sensor has magnetic field sensing sensitivities of 0 pm/Oe (Ch1) and 235 pm/Oe (Ch2). In addition, this paper also investigates the response of temperature. Under the temperature range of 20–40 °C, Ch1 and Ch2 have temperature sensitivities of −2000 pm/°C and 0 pm/°C, respectively. It is noteworthy that the two sensing channels respond to only a single physical parameter; this sensing performance is not common in dual-parameter sensing. Due to this sensing performance, it can be found that the magnetic field and temperature can be detected by this designed SPR-PCF sensor simultaneously without founding and calculating a sensing matrix. This sensing performance can solve the cross-sensitivity problem of magnetic field and temperature, thus reducing the measurement error. Since it can sense without a matrix, it further can solve the ill-conditioned matrix and nonlinear change in sensitivity problems in dual-parameter sensing. These excellent sensing capabilities are very important for carrying out multiparameter sensing in complicated environments.
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Vieira, Bernardo C., Fabrício V. Andrade i Antônio O. Fernandes. "Framework for Generating Configurable SAT Solvers". Journal of Integrated Circuits and Systems 6, nr 1 (27.12.2011): 50–59. http://dx.doi.org/10.29292/jics.v6i1.338.
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The state-of-the-art SAT solvers usually share the same core techniques, for instance: the watched literals structure, conflict clause recording and non-chronological backtracking. Nevertheless, they might differ in the elimination of learnt clauses, as well as in the decision heuristic. This article presents a framework for generating configurable SAT solvers. The proposed framework is composed of the following components: a Base SAT Solver, a Perl Preprocessor, XML files (Solver Description and Heuristics Description files) to describe each heuristic as well as the set of heuristics that the generated solver uses. This solvers may use several techniques and heuristics such as those implemented in BerkMin, and in Equivalence Checking of Dissimilar Circuits, and also in Minisat. In order to demonstrate the effectiveness of the proposed framework, this article also presents three distinct SAT solver instances generated by the framework to address a complex and challenging industry problem: the Combinational Equivalence Checking problem (CEC).The first instance is a SAT solver that uses BerkMin and Dissimilar Circuits core techniques except the learnt clause elimination heuristic that has been adapted from Minisat; the second is another solver that combines BerkMin and Minisat decision heuristics at run-time; and the third is yet another SAT solver that changes the database reducing heuristic at run-time. The experiments demonstrate that the first SAT solver generated is a faster solver than state-of-the-art SAT solver BerkMin for several instances as well as for Minisat in almost every instance.
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Webb, Penny. "A way to solve problems". Child Care 14, nr 3 (2.03.2017): 4–5. http://dx.doi.org/10.12968/chca.2017.14.3.4.
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Sargent, Marianne. "Science: How to solve problems". Child Care 15, nr 2 (2.02.2018): 8–9. http://dx.doi.org/10.12968/chca.2018.15.2.8.
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Liu, Xian Feng, Jia Hui Peng, Chang Hui Yang, Yu Yan Shu i Da Chang Wu. "The Effect of Surfactant and Alkali on the Surface Tension of Simulated Solutions of Alkali Activated Slag Cement System". Advanced Materials Research 399-401 (listopad 2011): 1246–50. http://dx.doi.org/10.4028/www.scientific.net/amr.399-401.1246.
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Alkali activated slag cement and concrete are high strength, rapid hardening, low heat of hydration, good durability and so on. Whereas, too high viscosity and bad workability of the fresh mixture is the crux of the matter to embarrass application of alkali-activated slag cement and concrete. Development of special superplasticizer for alkali activated slag cement and concrete is a worth exploring way to solve the problem, and the study on the surface tension of simulated solutions of alkali activated slag cement system is one of the basic researches about the special superplasticizer. In this paper, the surface tension of surfactant-alkali-water was studied by Wilhelmy method. The results showed, first, water-glass had the best efficacity of several alkali activators, when the modulus of water-glass was 1.5 and dosage of water-glass by Na2O was 8%, the surface tension was reduced by 33 mN/m and reduced to 39.9mN/m; second, [CH3(CH2)9]2N(CH3)2Cl had the best efficacity of several surfactants, when the concentration of [CH3(CH2)9]2N(CH3)2Cl was 50g/L, the surface tension was reduced by 35.3 mN/m and reduced to 32.5 mN/m; finally, the effect of surfactant and alkali together on the surface tension of water was complex, surfactants had hardly effective in water glass.
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Dhouib, Ikram, Philippe Guionneau, Tahar Mhiri i Zakaria Elaoud. "Synthesis, Crystal Structure and Characterization of [(CH3 CH2)4N] Mn1,5 Cl3 4H2O Cl 2(H2O)". JOURNAL OF ADVANCES IN CHEMISTRY 8, nr 2 (20.12.2012): 1639–50. http://dx.doi.org/10.24297/jac.v8i2.4044.
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Single crystals of [(CH3CH2)4N] Mn1,5 Cl3 4H2O Cl 2(H2O) were grown by the slow evaporation technique and characterized by means of single-crystal X-ray diffraction, FT-IR and Raman spectroscopy. The title compound belongs to the triclinic space group P with the following unit cell dimensions: a =7.5425(4) Å, b=9.8464 Å, c=13.7671(6) Å, α=89.951(3)°,β=89.753(3)°, γ=81.861(3)°, Z=4. These structures have solved using direct methods and refined by least-squares analysis. The structure was solved by the direct method and refined to final R value of 0.0567. The projection of [(CH3CH2)4N] Mn1,5 Cl3 4H2O Cl 2(H2O) in the plan (a,b) shows an arrangement in layers perpendicular to the direction b . The structure consists of infinite parallel two-dimensional planes built connected ions and water molecules by strong O-H…O and O-H…Cl hydrogen bonding.
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Ye, Manyuan, Guizhi Song, Wei Ren i Qiwen Wei. "Research on Current Backflow of Asymmetric CHB Multi-Level Inverter". Electronics 9, nr 2 (24.01.2020): 214. http://dx.doi.org/10.3390/electronics9020214.
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For the traditional asymmetric cascaded H-bridge multi-level inverters, the conventional hybrid modulation method has the problem of current backflow in a certain modulation index range. Although the monopolar modulation method effectively solves this problem, the high-voltage unit participates in the high-frequency operation in part of the range, which limits the improvement of the switching frequency of the whole system. The hybrid frequency modulation method can reduce the switching frequency of the high voltage unit to a certain extent, but the harmonic characteristics of the output voltage will be affected. In order to solve the above problems, a double frequency modulation method based on level-shifted PWM (LS-PWM) is proposed. On the one hand, it solves the inherent power back filling problem of the traditional hybrid modulation method, on the other hand, it ensures that the output voltage of the inverter has good harmonic characteristics when the switching frequency of the high voltage unit is low. The results of simulation and experiment prove the correctness of the theoretical analysis.
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Yu, Rena C., i Gonzalo Ruiz. "Multi-cracking modelling in concrete solved by a modified DR method". Computers and Concrete 1, nr 4 (25.11.2004): 371–88. http://dx.doi.org/10.12989/cac.2004.1.4.371.
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Fendji, Jean Louis Ebongue Kedieng, Clovis Tchuinte Kenmogne, David Jaurès Fotsa-Mbogne i Anna Förster. "Improving Farmers’ Revenue in Crop Rotation Systems with Plot Adjacency Constraints in Organic Farms with Nutrient Amendments". Applied Sciences 11, nr 15 (23.07.2021): 6775. http://dx.doi.org/10.3390/app11156775.
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The search for sustainable agriculture is leading many economies to turn to crop rotation systems and to abandon monoculture systems which generally require increased use of pesticides and synthetic fertilizers. But the optimization of crop rotation remains a challenge, especially when considering organic farming. This work tackles the optimization of crop rotation in traditional organic farms with plot adjacency constraints and nutrient amendments. In the present configuration, each farmer owns a certain quantity of rudimentary equipment and a number of workers, all considered as resources. Farms are subdivided into plots and each plot allows only one crop at a given period. At a given interval of time, each plot receives a certain quantity of nutrient. The generated rotations are of fixed durations for all plots and the objective is to maximize farmers’ income. A linear programming approach is used to determine the solution of the proposed farming model. Three levels of constraints are combined in the linear program to generate realistic rotations: (i) biophysical constraints including crop succession and plot adjacency; (ii) structural constraints including budget and resources; (iii) organizational constraints such as nutrient amendment and market demand. To evaluate the performance of the model, scenarios based on real-world data has been defined and solved using free solvers. The solutions obtained indicate that all the constrains are satisfied. In addition, farmers’ revenue is improved, reaching a stationary position when the quantity of available resources is equal or greater than the quantity of required resources. Finally, Cbc solver is faster than GLPK solver; and it provides solutions on larger instances where GLPK does not.
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Lopez-Ruiz, Gontzal, Joseba Castresana-Larrauri i Jesús María Blanco-Ilzarbe. "Thermodynamic Analysis of a Regenerative Brayton Cycle Using H2, CH4 and H2/CH4 Blends as Fuel". Energies 15, nr 4 (17.02.2022): 1508. http://dx.doi.org/10.3390/en15041508.
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Considering a simple regenerative Brayton cycle, the impact of using different fuel blends containing a variable volumetric percentage of hydrogen in methane was analysed. Due to the potential of hydrogen combustion in gas turbines to reduce the overall CO2 emissions and the dependency on natural gas, further research is needed to understand the impact on the overall thermodynamic cycle. For that purpose, a qualitative thermodynamic analysis was carried out to assess the exergetic and energetic efficiencies of the cycle as well as the irreversibilities associated to a subsystem. A single step reaction was considered in the hypothesis of complete combustion of a generic H2/CH4 mixture, where the volumetric H2 percentage was represented by fH2, which was varied from 0 to 1, defining the amount of hydrogen in the fuel mixture. Energy and entropy balances were solved through the Engineering Equation Solver (EES) code. Results showed that global exergetic and energetic efficiencies increased by 5% and 2%, respectively, varying fH2 from 0 to 1. Higher hydrogen percentages resulted in lower exergy destruction in the chamber despite the higher air-excess levels. It was also observed that higher values of fH2 led to lower fuel mass flow rates in the chamber, showing that hydrogen can still be competitive even though its cost per unit mass is twice that of natural gas.
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ARICI, Ferda Nur, i Ersin KAYA. "Hierarchical Approaches to Solve Optimization Problems". Academic Platform Journal of Engineering and Smart Systems 10, nr 3 (30.09.2022): 124–39. http://dx.doi.org/10.21541/apjess.1065912.
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Optimization is the operation of finding the most appropriate solution for a particular problem or set of problems. In the literature, there are many population-based optimization algorithms for solving optimization problems. Each of these algorithms has different characteristics. Although optimization algorithms give optimum results on some problems, they become insufficient to give optimum results as the problem gets harder and more complex. Many studies have been carried out to improve optimization algorithms to overcome these difficulties in recent years. In this study, six well-known population-based optimization algorithms (artificial algae algorithm - AAA, artificial bee colony algorithm - ABC, differential evolution algorithm - DE, genetic algorithm - GA, gravitational search algorithm - GSA, and particle swarm optimization - PSO) were used. Each of these algorithms has its own advantages and disadvantages. These population-based six algorithms were tested on CEC’17 test functions and their performances were examined and so the characteristics of the algorithms were determined. Based on these results, hierarchical approaches have been proposed in order to combine the advantages of algorithms and achieve better results. The hierarchical approach refers to the successful operation of algorithms. In this study, eight approaches were proposed, and performance evaluations of these structures were made on CEC’17 test functions. When the experimental results are examined, it is concluded that some hierarchical approaches can be applied, and some hierarchical approaches surpass the base states of the algorithms.
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Joan-Arinyo, R., M. V. Luzón i E. Yeguas. "Parameter tuning of PBIL and CHC evolutionary algorithms applied to solve the Root Identification Problem". Applied Soft Computing 11, nr 1 (styczeń 2011): 754–67. http://dx.doi.org/10.1016/j.asoc.2009.12.037.
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Runčevski, Tomče, Robert E. Dinnebier, Oxana V. Magdysyuk i Herbert Pöllmann. "Crystal structures of calcium hemicarboaluminate and carbonated calcium hemicarboaluminate from synchrotron powder diffraction data". Acta Crystallographica Section B Structural Science 68, nr 5 (17.08.2012): 493–500. http://dx.doi.org/10.1107/s010876811203042x.
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One of the main phases formed at the beginning of the carbonation reaction of cementitious building materials is the calcium hemicarboaluminate (abbreviated as Hc). This AFm (shorthand for hydrated calcium aluminate phases structurally related to hydrocalumite) phase was synthesized, crystallized and then studied by synchrotron X-ray powder diffraction and micro-Raman spectroscopy. At room temperature and standard experimental conditions two major cementitious phases were detected, the Hc phase (as a major phase) and carbonated calcium hemicarboaluminate (abbreviated as cHc). By increasing the temperature the Hc form transforms into cHc. The crystal structures of these important AFm phases were successfully solved and refined in the R\bar 3c space group of the trigonal crystal system. Hc has the unit-cell parameters a = 5.7757 (1) and c = 48.812 (2) Å, and cHc the unit-cell parameters a = 5.7534 (1) and c = 46.389 (1) Å. The two crystal structures are composed of positively charged main layers, [Ca4Al2(OH)12]2+, and negatively charged interlayers, [OH2n (CO3)1 − n ·4H2O]2−. The structure of the main layers is typical of the AFm family. Conversely, the interlayer region has a characteristic structure built up from water molecules and statistically distributed anions. In the interlayer, the Hc carbonate and hydroxyl anions are distributed in a 0.25:0.5 ratio, whereas the ratio of the anions in the cHc interlayers is 0.4:0.2.
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Cheng, Ling-Yi, Yu-Chi Wang, Ming-Hong Chen, Fu-I. Tung, Kuan-Ming Chiu i Tse-Ying Liu. "An Engineered Gene Nanovehicle Developed for Smart Gene Therapy to Selectively Inhibit Smooth Muscle Cells: An In Vitro Study". International Journal of Molecular Sciences 21, nr 4 (24.02.2020): 1530. http://dx.doi.org/10.3390/ijms21041530.
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In-stent restenosis is a serious concern for patients treated through the stenting procedure, although this can be solved using drug-eluting stents and/or drug-eluting balloon catheters. However, the chemical agents released from the drug-eluting layer for inhibiting smooth muscle cell (SMC) migration are inevitably associated with damage to vascular endothelial cell (ECs). The present in vitro study used a distinct strategy, in which a smart gene (phEGR1-PKCδ, an engineered plasmid consists of an SMC-specific promoter (human early growth response 1, hEGR1 promoter) ligated with a gene encoding apoptosis-inducing protein (protein kinase C-delta, PKCδ) was incorporated into a novel gene vehicle (Au cluster-incorporated polyethylenimine/carboxymethyl hexanoyl chitosan, PEI-Au/CHC) to form the PEI-Au/CHC/phEGR1-PKCδ complex, which was proposed for the selective inhibition of SMC proliferation. It was found that the cell viability of SMCs receiving the PEI-Au/CHC/phEGR1-PKCδ complex under simulated inflammation conditions was significantly lower than that of the ECs receiving the same treatment. In addition, the PEI-Au/CHC/phEGR1-PKCδ complex did not demonstrate an inhibitory effect on EC proliferation and migration under simulated inflammation conditions. Finally, the PEI-Au/CHC/phEGR1-PKCδ complexes coated onto a balloon catheter used in percutaneous transluminal coronary angioplasty (PTCA) could be transferred to both the ECs and the SMC layer of Sprague Dawley (SD) rat aortas ex vivo. These preliminary in vitro results suggest that the newly developed approach proposed in the present study might be a potential treatment for reducing the incidence rate of in-stent restenosis and late thrombosis in the future.
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Zhou, Weijun, Quan Yuan, Chris Li, Stephen F. Hahn, Kurt A. Koppi i Berend Hoek. "Thermoplastic Optical Polymers with Lead-Free Solder Reflow Resistance for HB-LED Packaging and Assembly". International Symposium on Microelectronics 2010, nr 1 (1.01.2010): 000156–63. http://dx.doi.org/10.4071/isom-2010-ta5-paper4.
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A new class of thermoplastic optical polymers made by substantially fully hydrogenating block copolymers of styrene and butadiene, known as cyclic block copolymers (CBCs), were recently discovered to exhibit lead-free solder reflow resistance with peak reflow temperature up to 260°C. This kind of behavior is uncommon for traditional thermoplastic polymers. The block copolymer design and the resulting nanostructured morphology lead to strong elastic and soft solid material characteristics for CBC, which may explain why CBCs can maintain good dimensional stability at high temperatures (i.e., above its glass transition temperature, Tg) for a short period of time such as in a solder reflow process. This hypothesis was examined by computational fluid dynamics modeling on a molded CBC lens of LUXEON K2 LED package configuration. When the CBC lens is subjected to a simulated solder reflow process, the change in physical dimension due to thermal expansion and gravity effects is predicted to be negligible. However, the residual stress in the molded lens may play a profound role on its dimensional stability. There exists a critical stress value below which no observable deformation is predicted for the CBC lens. With excellent optical transparency and good long term optical stability, low moisture absorption, and good injection moldability, CBCs is a promising class of materials for LED packaging that contributes to improved LED manufacturing economics.
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Nadimi-Shahraki, Mohammad H., Hoda Zamani, Ali Fatahi i Seyedali Mirjalili. "MFO-SFR: An Enhanced Moth-Flame Optimization Algorithm Using an Effective Stagnation Finding and Replacing Strategy". Mathematics 11, nr 4 (8.02.2023): 862. http://dx.doi.org/10.3390/math11040862.
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Moth-flame optimization (MFO) is a prominent problem solver with a simple structure that is widely used to solve different optimization problems. However, MFO and its variants inherently suffer from poor population diversity, leading to premature convergence to local optima and losses in the quality of its solutions. To overcome these limitations, an enhanced moth-flame optimization algorithm named MFO-SFR was developed to solve global optimization problems. The MFO-SFR algorithm introduces an effective stagnation finding and replacing (SFR) strategy to effectively maintain population diversity throughout the optimization process. The SFR strategy can find stagnant solutions using a distance-based technique and replaces them with a selected solution from the archive constructed from the previous solutions. The effectiveness of the proposed MFO-SFR algorithm was extensively assessed in 30 and 50 dimensions using the CEC 2018 benchmark functions, which simulated unimodal, multimodal, hybrid, and composition problems. Then, the obtained results were compared with two sets of competitors. In the first comparative set, the MFO algorithm and its well-known variants, specifically LMFO, WCMFO, CMFO, ODSFMFO, SMFO, and WMFO, were considered. Five state-of-the-art metaheuristic algorithms, including PSO, KH, GWO, CSA, and HOA, were considered in the second comparative set. The results were then statistically analyzed through the Friedman test. Ultimately, the capacity of the proposed algorithm to solve mechanical engineering problems was evaluated with two problems from the latest CEC 2020 test-suite. The experimental results and statistical analysis confirmed that the proposed MFO-SFR algorithm was superior to the MFO variants and state-of-the-art metaheuristic algorithms for solving complex global optimization problems, with 91.38% effectiveness.
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Li, Huixi, Yongluo Shen, Huidan Xi i Yinhao Xiao. "Complementary in Time and Space: Optimization on Cost and Performance with Multiple Resources Usage by Server Consolidation in Cloud Data Center". Applied Sciences 12, nr 19 (26.09.2022): 9654. http://dx.doi.org/10.3390/app12199654.
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The recent COVID-19 pandemic has accelerated the use of cloud computing. The surge in the number of users presents cloud service providers with severe challenges in managing computing resources. Guaranteeing the QoS of multiple users while reducing the operating cost of the cloud data center (CDC) is a major problem that needs to be solved urgently. To solve this problem, this paper establishes a cost model based on multiple computing resources in CDC, which comprehensively considers the hosts’ energy cost, virtual machine (VM) migration cost, and SLAV penalty cost. To minimize this cost, we design the following solution. We employ a convolutional autoencoder-based filter to preprocess the VM historical workload and use an attention-based RNN method to predict the computing resource usage of the VMs in future periods. Based on the predicted results, we trigger VM migration before the host enters an overloaded state to reduce the occurrence of SLAV. A heuristic algorithm based on the complementary use of multiple resources in space and time is proposed to solve the placement problem. Simulations driven by the VM real workload dataset validate the effectiveness of our proposed method. Compared with the existing methods, our proposed method reduces the energy consumption of the hosts and SLAV and reduces the total cost by 26.1~39.3%.
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Jia, Haolong, Jing Zuo, Qiliang Bao, Chao Geng, Yihan Luo, Ao Tang, Jing Jiang, Feng Li, Jianpeng Ren i Xinyang Li. "Discussion on Piston-Type Phase Ambiguity in a Coherent Beam Combining System". Photonics 9, nr 1 (17.01.2022): 49. http://dx.doi.org/10.3390/photonics9010049.
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Coherent beam combining (CBC) with closely arranged centrosymmetric arrays is a promising way to obtain a high-brightness laser. An essential task in CBC is to actively control the piston phases of the input beams, maintaining the correct phasing to maximize the combination efficiency. By applying the neural network, the nonlinear mapping relationship between the far-field image and the piston phase could be established, so that the piston phase can be corrected quickly with one step, which caused widespread concern. However, there exists a piston-type phase ambiguity problem in the CBC system with centrosymmetric arrays, which means that multiple different piston phases may generate the same far-field image. This will prevent the far-field image from correctly reflecting the phase information, which will result in a performance degradation of the image-based intelligent algorithms. In this paper, we make a theoretical analysis of phase ambiguity. A method to solve phase ambiguity is proposed, which requires no additional optical devices. We designed simulations to verify our conclusions and methods. We believe that our work solves the phase ambiguity problem in theory and is conducive to improving the performance of image-based algorithms.
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Chen, Guangjiao, i Guifen Chen. "An Improved Sparrow Algorithm Based on Small Habitats in Cooperative Communication Power Allocation". Electronics 12, nr 5 (27.02.2023): 1153. http://dx.doi.org/10.3390/electronics12051153.
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To solve the power allocation problem of multiple relays in cooperative communication, a sparrow improvement algorithm based on small habitats is proposed. First, the small-habitat rule increases the diversity of the energy classification of communication nodes. The problem of the premature convergence of the algorithm is solved. Subsequently, the joint jump rule is designed to replace the local search rule, and the local search rule of the sparrow algorithm is modified to avoid the local wandering phenomenon. The improved search method solves the local solution problem of the most available function. Lastly, a validation experiment of the performance of the algorithm is carried out according to the IEEE CEC 2017 benchmark document set. The simulation verifies the practicality of various algorithms. The maximum evaluation number (max FE) of the objective function is calculated to compare the performance of various algorithms. The experimental results show that the improved algorithm can increase the diversity of species. The multi-point search capability and global merit search capability are improved. Additionally, the convergence speed and computational accuracy of the algorithm are improved. The results show that the improved method is effective in controlling power in collaborative communication. The energy control algorithm has some practicality. The Friedman and Wilcoxon test criteria are applied and the convergence speed and computational accuracy of the improved algorithm are shown to be higher than those of other algorithms. This indicates that the improved power control method has some practicality in collaborative communication.
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Thị Phú, Phạm, i Nguyễn Lâm Đức. "Improving high school students’ ability to solve physics problems". Journal of Science, Educational Science 61, nr 8B (2016): 264–71. http://dx.doi.org/10.18173/2354-1075.2016-0183.
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Zapata, John, Afonso Azevedo, Carlos Fontes, Sergio Monteiro i Henry Colorado. "Environmental Impact and Sustainability of Calcium Aluminate Cements". Sustainability 14, nr 5 (26.02.2022): 2751. http://dx.doi.org/10.3390/su14052751.
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This investigation presents a critical analysis of calcium aluminate cements (CAC), specifically associated with sustainability and environmental impact, and the potential of these cements to help solve certain worldwide problems. Areas of research include cements as recycling holding materials, sustainability, circular economy, production costs, and energy. This investigation summarizes the current trends, perspectives, and the main concerns regarding CAC. Detailed information about the materials and processes involved in CAC is also presented. First, a general search was made using the Carrot2 Workbench metasearch engine to identify possible thematic groups correlated with CAC, then a more in-depth and specialized search was done using the Scopus database. The results revealed that these materials have a lot of potential to help solve problems in the circular economy and suggest several exciting areas for conducting future research.
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Agushaka, Jeffrey O., Olatunji Akinola, Absalom E. Ezugwu, Olaide N. Oyelade i Apu K. Saha. "Advanced dwarf mongoose optimization for solving CEC 2011 and CEC 2017 benchmark problems". PLOS ONE 17, nr 11 (2.11.2022): e0275346. http://dx.doi.org/10.1371/journal.pone.0275346.
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This paper proposes an improvement to the dwarf mongoose optimization (DMO) algorithm called the advanced dwarf mongoose optimization (ADMO) algorithm. The improvement goal is to solve the low convergence rate limitation of the DMO. This situation arises when the initial solutions are close to the optimal global solution; the subsequent value of the alpha must be small for the DMO to converge towards a better solution. The proposed improvement incorporates other social behavior of the dwarf mongoose, namely, the predation and mound protection and the reproductive and group splitting behavior to enhance the exploration and exploitation ability of the DMO. The ADMO also modifies the lifestyle of the alpha and subordinate group and the foraging and seminomadic behavior of the DMO. The proposed ADMO was used to solve the congress on evolutionary computation (CEC) 2011 and 2017 benchmark functions, consisting of 30 classical and hybrid composite problems and 22 real-world optimization problems. The performance of the ADMO, using different performance metrics and statistical analysis, is compared with the DMO and seven other existing algorithms. In most cases, the results show that solutions achieved by the ADMO are better than the solution obtained by the existing algorithms.
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Yeguas, Enrique, Robert Joan-Arinyo i María Victoria Luzón. "Modeling the Performance of Evolutionary Algorithms on the Root Identification Problem: A Case Study with PBIL and CHC Algorithms". Evolutionary Computation 19, nr 1 (marzec 2011): 107–35. http://dx.doi.org/10.1162/evco_a_00017.
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The availability of a model to measure the performance of evolutionary algorithms is very important, especially when these algorithms are applied to solve problems with high computational requirements. That model would compute an index of the quality of the solution reached by the algorithm as a function of run-time. Conversely, if we fix an index of quality for the solution, the model would give the number of iterations to be expected. In this work, we develop a statistical model to describe the performance of PBIL and CHC evolutionary algorithms applied to solve the root identification problem. This problem is basic in constraint-based, geometric parametric modeling, as an instance of general constraint-satisfaction problems. The performance model is empirically validated over a benchmark with very large search spaces.
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Farnad, Behnam, i Ahmad Jafarian. "A New Nature-Inspired Hybrid Algorithm with a Penalty Method to Solve Constrained Problem". International Journal of Computational Methods 15, nr 08 (31.10.2018): 1850069. http://dx.doi.org/10.1142/s021987621850069x.
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In this paper, an efficient hybrid method for solving constrained numerical and engineering optimization problems is presented. The proposed hybrid method uses a combination of three methods a genetic algorithm (GA), particle swarm optimization (PSO), and symbiotic organisms search (SOS) to find desired solution of problems in a complex design space and to control the feasibility of finding solutions using the penalty function method. There are three alternative phases in the proposed algorithm: GA, which develops and selects the best population for the next phases, PSO, which obtains the experiences for each appropriate solution and updates them, the SOS, which performs symbiotic interaction updates in real-world populations. For constraint handling, the penalty function method was used with same values to control the parameters based on the problem. The proposed algorithm was tested on a set of constrained problems from previous studies. Normality and non-parametric tests were performed on the proposed method. the obtained results have showed that the proposed method is able to score the best rank among the CEC 2010 competition algorithms. It is able to solve most of these numerical and engineering design problems up to the best desired solutions and reach the minimum number of function evaluations. The proposed method had a showed better performance than the [Formula: see text]DEag, which was the winner of the CEC 2010 competition.
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Nadimi-Shahraki, Mohammad H., Ali Fatahi, Hoda Zamani, Seyedali Mirjalili i Laith Abualigah. "An Improved Moth-Flame Optimization Algorithm with Adaptation Mechanism to Solve Numerical and Mechanical Engineering Problems". Entropy 23, nr 12 (6.12.2021): 1637. http://dx.doi.org/10.3390/e23121637.
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Moth-flame optimization (MFO) algorithm inspired by the transverse orientation of moths toward the light source is an effective approach to solve global optimization problems. However, the MFO algorithm suffers from issues such as premature convergence, low population diversity, local optima entrapment, and imbalance between exploration and exploitation. In this study, therefore, an improved moth-flame optimization (I-MFO) algorithm is proposed to cope with canonical MFO’s issues by locating trapped moths in local optimum via defining memory for each moth. The trapped moths tend to escape from the local optima by taking advantage of the adapted wandering around search (AWAS) strategy. The efficiency of the proposed I-MFO is evaluated by CEC 2018 benchmark functions and compared against other well-known metaheuristic algorithms. Moreover, the obtained results are statistically analyzed by the Friedman test on 30, 50, and 100 dimensions. Finally, the ability of the I-MFO algorithm to find the best optimal solutions for mechanical engineering problems is evaluated with three problems from the latest test-suite CEC 2020. The experimental and statistical results demonstrate that the proposed I-MFO is significantly superior to the contender algorithms and it successfully upgrades the shortcomings of the canonical MFO.
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Ran, Xu, Ji Yong Chen, Jun Guo Ran, Li Guo i Xing Dong Zhang. "Synthesis of Nanosized Carbonated Hydroxyapatite under Microwave Irradiation". Key Engineering Materials 330-332 (luty 2007): 303–6. http://dx.doi.org/10.4028/www.scientific.net/kem.330-332.303.
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In order to solve the problems on synthesizing carbonated hydroxyapatites (CHA) by the conventional heating precipitation method, such as long reaction and large particle size, poor crystallinity of CHA etc, the nanosized CHA particles have been synthesized by microwave heating method using phosphoric acid (H3PO4), calcium hydroxide (Ca(OH)2) and calcium carbonate (CaCO3 ) as starting materials in the present paper. The influences of power level and time of microwave irradiation on synthesis of CHA have been investigated. The X-ray diffraction (XRD) analysis has indicated that microwave heating will reduce CHA crystallization time and improve crystallinity of CHA. Scanning electron microscope (SEM) analysis has showed that CHA particles are of rod like morphology with about 60nm width and 200nm length respectively. Infrared spectroscopy (IR) analysis has confirmed the B-type CHA precipitate can be formed under microwave irradiation. The microwave irradiation plays an important role to promote the reaction and the synthesis of nanosized CHA particles.
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Sakhnenko, Mykola, Hanna Karakurkchi, Tetiana Nenastina, Irina Yermolenko i Alla Korohodska. "Features of CЕС technology for eco- and energytechnologies". Bulletin of the National Technical University «KhPI» Series: New solutions in modern technologies, nr 3(9) (18.10.2021): 89–96. http://dx.doi.org/10.20998/2413-4295.2021.03.13.
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Based on the analysis of the peculiarities of CEC formation, it is shown that their production and application is one of the world trends in functional electroplating and allows to solve a number of practical problems, in particular in the field of eco- and energy technologies. The deposition of polyfunctional CECs of cobalt with refractory metals was carried out from citrate-pyrophosphate electrolytes in galvanostatic and pulsed modes. The obtained composite coatings have a complex of increased mechanical and anti-corrosion properties, catalytic and photocatalytic activity, which determines the prospects for the use of the obtained thin-film materials in many industries. It is shown that the processes of formation of such multicomponent systems are very complex, a separate problem that needs to be solved is the organization of the technological process of CEC adapted to production needs. The scheme of organization of technological process on the basis of the modular approach which is based on results of complex researches of influence of quantitative characteristics of working electrolytes and modes of electrolysis on structure and properties of the synthesized coverings is developed. The generalized scheme of CEC technology reflects the sequence of generally accepted processes and operations in electrochemical production with the possibility of applying the modular principle of organization of galvanic sites and shops. Variability of technological schemes provides flexible control of the composition and properties of coatings by changing the time and energy characteristics of electrodeposition with insignificant adjustment of the quantitative and qualitative composition of electrolytes. The developed modular approach in the organization of technological process can be used as a basis for other electrochemical technologies of synthesis of functional materials.
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Liu, Yixin, Kai Zhou i Yu Lei. "Using Bayesian Inference Framework towards Identifying Gas Species and Concentration from High Temperature Resistive Sensor Array Data". Journal of Sensors 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/351940.
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High temperature gas sensors have been highly demanded for combustion process optimization and toxic emissions control, which usually suffer from poor selectivity. In order to solve this selectivity issue and identify unknown reducing gas species (CO, CH4, and CH8) and concentrations, a high temperature resistive sensor array data set was built in this study based on 5 reported sensors. As each sensor showed specific responses towards different types of reducing gas with certain concentrations, based on which calibration curves were fitted, providing benchmark sensor array response database, then Bayesian inference framework was utilized to process the sensor array data and build a sample selection program to simultaneously identify gas species and concentration, by formulating proper likelihood between input measured sensor array response pattern of an unknown gas and each sampled sensor array response pattern in benchmark database. This algorithm shows good robustness which can accurately identify gas species and predict gas concentration with a small error of less than 10% based on limited amount of experiment data. These features indicate that Bayesian probabilistic approach is a simple and efficient way to process sensor array data, which can significantly reduce the required computational overhead and training data.
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Li, Jiajian, Shuai Cao i Erol Yilmaz. "Characterization of Macro Mechanical Properties and Microstructures of Cement-Based Composites Prepared from Fly Ash, Gypsum and Steel Slag". Minerals 12, nr 1 (21.12.2021): 6. http://dx.doi.org/10.3390/min12010006.
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Using solid wastes (SWs) as backfilling material to fill underground mined-out areas (UMOAs) solved the environmental problems caused by SWs and reduced the backfilling cost. In this study, fly ash (FA), gypsum and steel slag (SS) were used to prepare cement-based composites (CBC). The uniaxial compression, computed tomography (CT) and scanning electron microscope (SEM) laboratory experiments were conducted to explore the macro and micromechanical properties of CBC. The findings showed that the uniaxial compressive strength (UCS) of CBC with a curing time of 7 d could reach 6.54 MPa. The increase of SS content reduced the UCS of CBC, while the gypsum and FA content could increase the UCS of CBC. Microscopic studies have shown that the SS particles in CBC have noticeable sedimentation, and the increase of SS content causes the failure mode of CBC from tensile to tensile-shear. These research results can provide a scientific reference for the preparation of backfilling materials.
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Gheorghiu, Călin-Ioan. "Accurate Spectral Collocation Solutions to 2nd-Order Sturm–Liouville Problems". Symmetry 13, nr 3 (27.02.2021): 385. http://dx.doi.org/10.3390/sym13030385.
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This work is about the use of some classical spectral collocation methods as well as with the new software system Chebfun in order to compute the eigenpairs of some high order Sturm–Liouville eigenproblems. The analysis is divided into two distinct directions. For problems with clamped boundary conditions, we use the preconditioning of the spectral collocation differentiation matrices and for hinged end boundary conditions the equation is transformed into a second order system and then the conventional ChC is applied. A challenging set of “hard” benchmark problems, for which usual numerical methods (FD, FE, shooting, etc.) encounter difficulties or even fail, are analyzed in order to evaluate the qualities and drawbacks of spectral methods. In order to separate “good” and “bad” (spurious) eigenvalues, we estimate the drift of the set of eigenvalues of interest with respect to the order of approximation N. This drift gives us a very precise indication of the accuracy with which the eigenvalues are computed, i.e., an automatic estimation and error control of the eigenvalue error. Two MATLAB codes models for spectral collocation (ChC and SiC) and another for Chebfun are provided. They outperform the old codes used so far and can be easily modified to solve other problems.
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Chang, Kai-Chun, You-Tun Teng i Wen-Long Chin. "High-Throughput CBC Mode Crypto Circuit". Electrical Science & Engineering 5, nr 1 (24.05.2023): 20–30. http://dx.doi.org/10.30564/ese.v5i1.5636.
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The objective of this study is to investigate a high-throughput cipher-block chaining (CBC) mode crypto circuit, which can be embedded in commercial home gateways or switches/routers. Concurrently, the area efficiency of block ciphers can be improved as well. However, the CBC mode encounters the problem of data dependency. To solve this issue, a data scheduling mechanism of network packets is proposed to eliminate the data dependency of input data for CBC mode pipelined crypto engines. The proposed CBC mode architecture can be applied to advanced encryption standards (AES), triple data encryption standards (3DES), and other block ciphers. In addition, to increase the throughput, deeply pipelined AES-CBC and 3DES-CBC circuits with balanced paths are proposed. With the proposed scheduling and pipelined circuits, the authors can effectively encrypt the packet data of multiple network channels at the same time. Using the proposed architecture, throughputs of 137.8 and 44.75 Gbps using a copy of pipelined AES-CBC and 3DES-CBC circuits can be achieved in TSMC 45 nm and TSMC 130 nm processes, respectively.
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Tran, Van-Thuan, Minh-Khai Nguyen, Cao-Cuong Ngo i Youn-Ok Choi. "Three-Phase Five-Level Cascade Quasi-Switched Boost Inverter". Electronics 8, nr 3 (6.03.2019): 296. http://dx.doi.org/10.3390/electronics8030296.
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This paper presents a three-phase cascaded five-level H-bridge quasi-switched boost inverter (CHB-qSBI). The merits of the CHB-qSBI are as follows: single-stage conversion, shoot-through immunity, buck-boost voltage, and reduced passive components. Furthermore, a PWM control method is applied to the CHB-qSBI topology to improve the modulation index. The voltage stress across power semiconductor devices and the capacitor are significantly lower using improved pulse-width modulation (PWM) control. Additionally, by controlling individual shoot-through duty cycle, the DC-link voltage of each module can achieve the same values. As a result, the imbalance problem of the DC-link voltage can be solved. A detailed analysis and operating principle with the modulation scheme and comprehensive comparison for the CHB-qSBI are illustrated. The experimental and simulation results are presented to validate the operating principle of the three-phase CHB-qSBI.
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Wu, Binbin, Bangning Zhang, Wenfeng Ma, Chen Xie, Daoxing Guo i Hao Jiang. "Motion Planning in UAV-Aided Data Collection with Dynamic Jamming". Electronics 12, nr 8 (13.04.2023): 1841. http://dx.doi.org/10.3390/electronics12081841.
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Unmanned-aerial-vehicle (UAV)-aided data collection for Internet of Things applications has attracted increasing attention. This paper investigates motion planning for UAV collecting low-power ground sensor node (SN) data in a dynamic jamming environment. We targeted minimizing the flight energy consumption via optimization of the UAV trajectory while considering the indispensable constraints which cover the collection data demodulation threshold, obstacle avoidance, data collection volume, and motion principle. Firstly, we formulate the UAV-aided data collection problem as an energy consumption minimization problem. To solve this nonconvex optimization problem, we rewrite the original problem by introducing relaxation variables and constructing equivalence constraints to obtain a new relaxation convex problem, which can be solved iteratively using the successive convex approximation (SCA) method. However, SCA is susceptible to initial values, especially in dynamic environments where fixed initial values may lead to a wide range of results, making it difficult to obtain a truly optimal solution to the optimization problem. To solve the initial value problem in dynamic environments, we further propose a communication-flight-corridor(CFC)-based initial path generation method to improve the reliability and convergence speed of the SCA method by constructing reliable communication regions and resilient secure paths in real time. Finally, simulation results validate the performance of the proposed algorithm compared to the benchmark algorithms under different parameter configurations.
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Mujiati, Mujiati, Eva Sulistiowati i Siti Nurhasanah. "Role of community figure in Healthy Indonesia Program with family approach (PIS-PK) in Banjarnegara District, Central Java". Journal of Community Empowerment for Health 3, nr 3 (31.12.2020): 178. http://dx.doi.org/10.22146/jcoemph.56971.
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The involvement of community figure is one form of participation in health development, including in the Healthy Indonesia Program with Family Approach (PIS-PK). The purpose of this study was to determine the role of community figure in PIS-PK. The type of study was a qualitative study in one kelurahan which was included in the working area of Community Health Care (CHC) Banjarnegara 1 in Banjarnegara District, Central Java, which was chosen purposively. Data collection was done by in-depth interview. The key informants were community figure, namely from the kelurahan (kelurahan head and its staff) and community members who were considered community figure in the village. Data triangulation was done by conducting in-depth interview with the head and staff of community health centre and the community. Data that has been obtained was analyzed thematically. The results of the study showed that community figure played an important role in the implementation of PIS-PK as sources of information about PIS-PK, helping field organizing, helping prepare complete families documents, assisting CHC staff and surveyor in home visits and helping solve problems that arise, and generally playing a role in the smooth implementation of PIS-PK. Social support from the local government and communities can be a motivation to continue to play a role in supporting the success of PIS-PK.
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Tran Thi Le, Thu, Ai Nguyen Thi Nhan, Thuy Pham Thi Dieu i Van Nguyen Thi. "Psychological difficulties & school psychology support for Junior high school & High school students in Ho Chi Minh City". Journal of Science Educational Science 65, nr 9 (wrzesień 2020): 69–80. http://dx.doi.org/10.18173/2354-1075.2020-0094.
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This study aims to survey the state of psychological health, specifically the psychological difficulties of 231 junior high school and high school students in Ho Chi Minh City (111 high school pupils & 120 junior high school pupils) through a self-report survey on those areas: (1) Study; (2) Psychophysiological development; (3) Communication with friends; (4) Communication with parents; (5) Communication with teachers. 111 high schoolersalso completed one more area, which is vocational orientation. Research results showed that junior high schoolersface the most difficulties in the field of study, high school students have the most difficulties in the field of study, vocational orientation and psychological development. The level of psychological difficulty in pupils are different in terms of grade level, gender, education, family's economic situation, and mother's educational level. The study also showed that junior and high school students often choose to solve their psychological difficulties by sharing with friends, confiding with their parents, relatives and participating in collective activities. About half of the students were satisfied with the schoolpsychological support givento them. Most teachers believed that students should be assisted by psychologists, not teachers and school facilities regarding this problem.
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Bossa, Jean-Baptiste, Fabien Borget, Fabrice Duvernay, Grégoire Danger, Patrice Theulé i Thierry Chiavassa. "Solid-State Methylamine VUV Irradiation Study Using Carbon Monoxide as an H Radical Scavenger". Australian Journal of Chemistry 65, nr 2 (2012): 129. http://dx.doi.org/10.1071/ch11409.
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Solid-phase methylamine (CH3NH2) was vacuum ultraviolet (VUV) photoprocessed at low temperature (20 K) using a hydrogen flow discharge lamp, which allows irradiation down to 120 nm. Methanimine (CH2=NH), the methylammonium cation (CH3NH3+) and the counterion CN–, as well as the amino radical (NH2), methane (CH4) and ammonia (NH3), were identified as the photoproducts by using FTIR spectroscopy. So far, the branching ratios of the photodissociation pathways of methylamine in the solid phase remain unknown. The methylamine molecule holds two non-equivalent hydrogen atoms on the methyl and the amino group, so we can expect the formation of two distinct radicals via a carbon–hydrogen or a nitrogen–hydrogen bond cleavage, namely CH2NH2 and CH3NH. These radicals are highly reactive and may reform methylamine with hydrogen atom recombination. Their direct infrared spectroscopic detection is therefore tricky. To solve that problem, we use carbon monoxide (CO) as an H radical scavenger, forming the intermediate species HCO. After the irradiation of a CH3NH2 : CO binary ice mixture, formamide (NH2CHO) and N-methylformamide (CH3NHCHO) were identified as the main photoproducts using both infrared and mass spectrometry. We give a rough approximation of the branching ratios, which are in agreement with previous studies in the gas phase.
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Baumgaertner, A. J. G., P. Jöckel, B. Steil, H. Tost i R. Sander. "A fast stratospheric chemistry solver: the E4CHEM submodel for the atmospheric chemistry global circulation model EMAC". Geoscientific Model Development 3, nr 1 (22.06.2010): 321–28. http://dx.doi.org/10.5194/gmd-3-321-2010.
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Abstract. The atmospheric chemistry general circulation model ECHAM5/MESSy (EMAC) and the atmospheric chemistry box model CAABA are extended by a computationally very efficient submodel for atmospheric chemistry, E4CHEM. It focuses on stratospheric chemistry but also includes background tropospheric chemistry. It is based on the chemistry of MAECHAM4-CHEM and is intended to serve as a simple and fast alternative to the flexible but also computationally more demanding submodel MECCA. In a model setup with E4CHEM, EMAC is now also suitable for simulations of longer time scales. The reaction mechanism contains basic O3, CH4, CO, HOx, NOx, and ClOx gas phase chemistry. In addition, E4CHEM includes optional fast routines for heterogeneous reactions on sulphate aerosols and polar stratospheric clouds (substituting the existing submodels PSC and HETCHEM), and scavenging (substituting the existing submodel SCAV). We describe the implementation of E4CHEM into the MESSy structure of CAABA and EMAC. For some species the steady state in the box model differs by up to 100% when compared to results from CAABA/MECCA due to different reaction rates. After an update of the reaction rates in E4CHEM the mixing ratios in both boxmodel and 3-D model simulations are in satisfactory agreement with the results from a simulation where MECCA with a similar chemistry scheme was employed. Finally, a comparison against a simulation with a more complex and already evaluated chemical mechanism is presented in order to discuss shortcomings associated with the simplification of the chemical mechanism.
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Baumgaertner, A. J. G., P. Jöckel, B. Steil, H. Tost i R. Sander. "A fast stratospheric chemistry solver: the E4CHEM submodel for the atmospheric chemistry global circulation model EMAC". Geoscientific Model Development Discussions 3, nr 1 (17.02.2010): 181–200. http://dx.doi.org/10.5194/gmdd-3-181-2010.
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Abstract. The atmospheric chemistry general circulation model ECHAM5/MESSy (EMAC) and the atmospheric chemistry box model CAABA are extended by a computationally very efficient submodel for atmospheric chemistry, E4CHEM. It focuses on stratospheric chemistry but also includes background tropospheric chemistry. It is based on the chemistry of MAECHAM4-CHEM and is intended to serve as a simple and fast alternative to the flexible but also computationally more demanding submodel MECCA. In a model setup with E4CHEM, EMAC is now also suitable for simulations of longer time scales. The reaction mechanism contains basic O3, CH4, CO, HOx, NOx and ClOx gas phase chemistry. In addition, E4CHEM includes optional fast routines for heterogeneous reactions on sulphate aerosols and polar stratospheric clouds (substituting the existing submodels PSC and HETCHEM), and scavenging (substituting the existing submodel SCAV). We describe the implementation of E4CHEM into the MESSy structure of CAABA and EMAC. For some species the steady state in the box model differs by up to 100% when compared to results from CAABA/MECCA due to different reaction rates. After an update of the reaction rates in E4CHEM the mixing ratios in both boxmodel and 3-D model simulations are in satisfactory agreement with the results from a simulation where MECCA with a similar chemistry scheme was employed. Finally, a comparison against a simulation with a more complex and already evaluated chemical mechanism is presented in order to discuss shortcomings associated with the simplification of the chemical mechanism.
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Mizukami, Yuzo, i Yuichi Yamaguchi. "Method for the Analysis of Tea Aroma by using Solvent-assisted Flavor Evaporation Apparatus". Chagyo Kenkyu Hokoku (Tea Research Journal) 2010, nr 110 (2010): 110_105–110_112. http://dx.doi.org/10.5979/cha.2010.110_105.
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Wilson, William W., Karl O. Christe, Jin-an Feng i Robert Bau. "Tetramethylammonium bifluoride, crystal structure and vibrational spectra". Canadian Journal of Chemistry 67, nr 11 (1.11.1989): 1898–901. http://dx.doi.org/10.1139/v89-295.
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Single crystals of [N(CH3)4]HF2 were obtained as a by-product during the recrystallization of [N(CH3)4]ClF4 from CH3CN solution. X-ray diffraction data show that [N(CH3)4]HF2 crystallizes in the orthorhombic space group Pmn21 with Z = 2 and unit cell dimensions a = 6.611(5), b = 8.753(5), and c = 5.386(4) Å. The structure was solved by direct methods and refined by least squares to a final R = 0.055 by using 205 independent reflections. The HF2− anions are symmetric, exhibit an unusually short [Formula: see text] distance of 2.213(4) Å, and vibrational frequencies close to those of the free HF2− anion. Keywords: tetramethylammonium bifluoride, crystal structure, Raman spectrum.
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Leshok, D. Y., N. N. Golovnev i S. D. Kirik. "Cystamindi-ium tetrachlorocuprate [NH3(CH2)2SS(CH2)2NH3][CuCl4]: synthesis, crystal structure, and thermal decomposition". Powder Diffraction 30, nr 2 (11.03.2015): 163–69. http://dx.doi.org/10.1017/s0885715614001390.
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The salt [NH3(CH2)2SS(CH2)2NH3][CuCl4] was obtained by crystallization after adding CuCl2 to cystamine (Cysta), solved in hydrochloric acid. The assumption of conserved disulfide connection (S–S) in the compound, made on the basis of infrared spectroscopy, is further supported by the crystal structure determined from X-ray powder diffraction data. The compound has an ionic structure. [CuCl4]2− and CystaH22+ ions package in the form of inorganic and organic layers in the cell, interconnected through the formation of hydrogen bonds via NH3-groups and chlorine atoms of the complex [CuCl4]2−. Inorganic layers are additionally stabilized in the parquet package of [CuCl4]2− ions which provides a Cu-distorted octahedral coordination. CystaH2[CuCl4] is stable in air up to 200 °C. Thermal decomposition occurs in several stages, accompanied by breaking of S–S bonds, releasing of the organic component and yielding CuO.
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Mehta, Shikha. "Memetic Algorithm with Constrained Local Search for Large-Scale Global Optimization". Journal of Intelligent Systems 26, nr 2 (1.04.2017): 287–300. http://dx.doi.org/10.1515/jisys-2015-0103.
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AbstractNature-inspired algorithms are seen as potential tools to solve large-scale global optimization problems. Memetic algorithms (MAs) are nature-inspired techniques based on evolutionary computation. MAs are considered as modified genetic algorithms integrated with a local search mechanism. Conventional MAs perform well for small dimensions; however, their performance starts declining with the increase in dimensions. It is popularly known as the “curse of dimensionality” problem. In order to solve this problem, MA with constrained local search (MACLS) is proposed for single-objective optimization problems. MACLS restricts the local search to be performed after every generation. Controlled local search enhances the optimization capability of the MA. MACLS has been evaluated with respect to GS-MPSO (the latest modification of MA) and MLCC, EPUS-PSO, JDEdynNP-F, MTS, DewSAcc, DMS-PSO, LSEDA-gl, UEP, ALPSEA, classical DE (differential evolution), and real-coded CHC algorithms that participated in the Congress on Evolutionary Computation 2008 competition. The results establish that MACLS significantly outperforms these algorithms in attaining global optima for unimodal and multimodal single-objective optimization problems for small as well as large dimensions.
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Singh, Pratap, Rishi Pal Singh, Yudhvir Singh, Jana Shafi i Muhammad Fazal Ijaz. "An Enhanced Naked Mole Rat Algorithm for Optimal Cross-Layer Solution for Wireless Underground Sensor Networks". Mathematics 9, nr 22 (18.11.2021): 2942. http://dx.doi.org/10.3390/math9222942.
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Nature-inspired algorithms serve as the backbone of modern computing technology, and over the past three decades, the field has grown enormously. Many applications were solved by such algorithms and are replacing the traditional classical optimization processes. A recent naked mole-rat algorithm (NMRA) was proposed based on the mating patterns of naked mole-rats. This algorithm proved its worth in terms of competitiveness and application to various domains of research. The aim was to propose an algorithm based on NMRA, named enhanced NMRA (ENMRA), by mitigating the problems that this algorithm suffers from: slow convergence, poor exploration, and local optima stagnation. To enhance the exploration capabilities of basic NMRA, grey wolf optimization (GWO)-based search equations were employed. Exploitation was improved using population division methods based on local neighborhood search (LNS) and differential evolution (DE) equations. To avoid the local stagnation problem, a neighborhood search strategy around the best individual was utilized. Such improvements help the new variant to solve highly challenging optimization problems in contrast to existing algorithms. The efficacy of ENMRA was evaluated using CEC 2019 benchmark test suite. The results were statistically analyzed by the Wilcoxon rank-sum test and Friedman rank (f-rank) test. The resulting analysis proved that ENMRA is superior to the competitive algorithms for test functions CEC 2019 with overall effectiveness of 60.33%. Moreover, the real-world optimization problem from underground wireless sensor networks for an efficient cross-layer solution was also used to test the efficiency of ENMRA. The results of comparative study and statistical tests affirmed the efficient performance of the proposed algorithm.