A thermodynamic approach to viscoelasticity and plasticity

Summary In the present paper a constitutive equation of rate type is derived from Onsager's theory of non-equilibrium processes. Some simple solutions of the equation are discussed, and it is found that the material at hand exhibits different kinds of relaxation phenomena, normal stress effects, non-Newtonian behaviour, plastic properties as well as the creep and elasticity at small loads.With 6 Figures     

A cement Vertical Roller Mill modeling based on the number of breakages

This study investigated a mathematical model for an industrial-scale vertical roller mill(VRM) at the Ilam Cement Plant in Iran. The model was calibrated using the initial survey's data, and the breakage rates of clinker were then back-calculated. The modeling and validation results demonstrated that according to the bed-breakage mechanism in VRM, clinker particles only stay in the VRM for a short time. Particles in the VRM haven't a 1 to 3 times greater chance of breaking due to their brief time in the VRM. Matrix model's results model provides a more robust prediction based on the number of 2-times clinker breakage in VRMs (R² = 0.9916, MSE = 5.3526, accuracy = 94.6474). Also shown by the results of the matrix modeling, the S increased with decreasing the particle size. In contrast, the population balance model increased with increased particle size.     

Identifying emerging technologies using expert opinions on the future: A topic modeling and fuzzy clustering approach

Scientometrics - As technology rapidly advances with the Fourth Industrial Revolution, many emerging technologies have been developed in several technology sectors. These technologies can (1)...     

An approach to accidents modeling based on compounds road environments

The most common approach to study the influence of certain road features on accidents has been the consideration of uniform road segments characterized by a unique feature. However, when an accident is related to the road infrastructure, its cause is usually not a single characteristic but rather a complex combination of several characteristics. The main objective of this paper is to describe a methodology developed in order to consider the road as a complete environment by using compound road environments, overcoming the limitations inherented in considering only uniform road segments. The methodology consists of: dividing a sample of roads into segments; grouping them into quite homogeneous road environments using cluster analysis; and identifying the influence of skid resistance and texture depth on road accidents in each environment by using generalized linear models. The application of this methodology is demonstrated for eight roads. Based on real data from accidents and road characteristics, three compound road environments were established where the pavement surface properties significantly influence the occurrence of accidents. Results have showed clearly that road environments where braking maneuvers are more common or those with small radii of curvature and high speeds require higher skid resistance and texture depth as an important contribution to the accident prevention.     

A first-principles thermodynamic approach to ordering in binary alloys

The communication reviews the augmented space based approaches to thermodynamics and ordering of binary alloys. We give several examples of metallic alloys to illustrate our methodology.     

A thermodynamic approach to the influence of plastic deformation on crack instability

It is argued that the role of plastic deformation in crack growth has been widely misinterpreted. In particular the notion that the work of plastic deformation contributes to the energy balance in such a way as to give rise to an increased effective surface energy is shown to be physically incorrect. A fundamental reappraisal of the role of plastic deformation on the instability of cracks is undertaken and a thermodynamic formulation of the problem of the energetics of crack extension is developed. This is capable of treating both moving cracks and the dislocations producing plastic deformation in a unified manner and provides a powerful tool for the study of combined crack extension and plastic deformation. A rigorous definition of plastic work is also given and it is shown that the crack extension force is the only physically meaningful parameter which can be used in the formulation of a crack instability criterion. The work of plastic deformation is not a part of the crack extension force and should not be included in the criterion for crack instability. It is found that one of the important effects of plastic deformation on crack instability is the shielding effect or the reduction it causes in the magnitude of the stress at the crack tip resulting in a smaller crack extension force. Other possible effects of plastic deformation on crack propagation are briefly discussed.     

Classifying and ranking topic terms based on a novel approach: role differentiation of author keywords

In traditional bibliometric analysis, author keywords (AKs) play a critical role in such areas as information query, co-word analysis, and capturing topic terms. In past decades, the most relevant studies have focused on the weighting methods of AKs to find specialty or discriminated terms for a topic; however, very few explorations touched the issue of role differentiation for AKs within a specific topic or the context of topic query. Furthermore, either traditional co-word analysis or the latest semantic modeling methods still face the challenges on accurate classifying and ranking the keywords/terms for a specific research topic. As a complement to prior research, a novel analytical framework based on role differentiation of AKs and Technique for Order of Preference by Similarity to Ideal Solution is proposed in this article. In addition, a case study on additive manufacturing is conducted to verify the proposed framework.     

A general approach to modeling CUSUM charts for a proportion

This paper considers two CUmulative SUM (CUSUM) charts for monitoring a process when items from the process are inspected and classified into one of two categories, namely defective or non-defective. The purpose of this type of process monitoring is to detect changes in the proportion p of items in the first category. The first CUSUM chart considered is based on the binomial variables resulting from counting the total number of defective items in samples of n items. A point is plotted on this binomial CUSUM chart after n items have been inspected. The second CUSUM chart considered is based on the Bernoulli observations corresponding to the inspection of the individual items in the samples. A point is plotted on this Bernoulli CUSUM chart after each individual inspection, without waiting until the end of a sample. The main objective of the paper is to evaluate the statistical properties of these two CUSUM charts under a general model for process sampling and for the occurrence of special causes that change the value of p. This model applies to situations in which there are inspection periods when n items are inspected and non-inspection periods when no inspection is done. This model assumes that there is a positive time between individual inspection results, and that a change in p can occur anywhere within an inspection period or a non-inspection period. This includes the possibility that a shift can occur during the time that a sample of n items is being taken. This model is more general and often more realistic than the simpler model usually used to evaluate properties of control charts. Under our model, it is shown that there is little difference between the binomial CUSUM chart and the Bernoulli CUSUM chart, in terms of the expected time required to detect small and moderate shifts in p, but the Bernoulli CUSUM chart is better for detecting large shifts in p. It is shown that it is best to choose a relatively small sample size when applying the CUSUM charts. As expected, the CUSUM charts are substantially faster than the traditional Shewhart p-chart for detecting small shifts in p. But, surprisingly, the CUSUM charts are also better than the p-chart for detecting large shifts in p.     

A methodology for selecting a green technology portfolio based on synergy

Green manufacturing (GM) is a kind of modern manufacturing mode with the full consideration of resources consumption and environmental impact. The publication of EMS ISO14000, OHSAS18000, environmental label system and environmental regulations has also promoted the practice of GM in real production to a large extent. In order to help enterprises to effectively implement GM with limited environmental investment, we present a methodology for selecting a green technology portfolio from the perspective of environmental strategy. The enterprise benefits derived from each portfolio, including economic and environmental benefits, are evaluated by six main objectives: cost, quality, time, service, resource consumption, and environmental impact. In addition, the synergies among the different types of technologies in one green technology portfolio are also taken into account. Lastly, an illustrative example provides some insights into the application of this methodology.     

Semantic Academic Profiler (SAP): a framework for researcher assessment based on semantic topic modeling

Recent efforts have focused on identifying multidisciplinary teams and detecting co-Authorship Networks based on exploring topic modeling to identify researchers’ expertise. Though promising, none of these efforts perform a real-life evaluation of the quality of the built topics. This paper proposes a Semantic Academic Profiler (SAP) framework that allows summarizing articles written by researchers to automatically build research profiles and perform online evaluations regarding these built profiles. SAP exploits and extends state-of-the-art Topic Modeling strategies based on Cluwords considering n-grams and introduces a new visual interface able to highlight the main topics related to articles, researchers and institutions. To evaluate SAP’s capability of summarizing the profile of such entities as well as its usefulness for supporting online assessments of the topics’ quality, we perform and contrast two types of evaluation, considering an extensive repository of Brazilian curricula vitae: (1) an offline evaluation, in which we exploit a traditional metric (NPMI) to measure the quality of several data representations strategies including (i) TFIDF, (ii) TFIDF with Bi-grams, (iii) Cluwords, and (iv) CluWords with Bi-grams; and (2) an online evaluation through an A/B test where researchers evaluate their own built profiles. We also perform an online assessment of SAP user interface through a usability test following the SUS methodology. Our experiments indicate that the CluWords with Bi-grams is the best solution and the SAP interface is very useful. We also observed essential differences in the online and offline assessments, indicating that using both together is very important for a comprehensive quality evaluation. Such type of study is scarce in the literature and our findings open space for new lines of investigation in the Topic Modeling area.

     

A new approach to journal co-citation matrix construction based on the number of co-cited articles in journals

Scientometrics - Co-citation analysis is one of the most important methods in information science. Journal co-citation analysis has been widely used to analyze the relevance, relationship and...     

A topic model approach to measuring interdisciplinarity at the National Science Foundation

As the National Science Foundation (NSF) implements new cross-cutting initiatives and programs, interest in assessing the success of these experiments in fostering interdisciplinarity grows. A primary challenge in measuring interdisciplinarity is identifying and bounding the discrete disciplines that comprise interdisciplinary work. Using statistical text-mining techniques to extract topic bins, the NSF recently developed a topic map of all of their awards issued between 2000 and 2011. These new data provide a novel means for measuring interdisciplinarity by assessing the language or content of award proposals. Using the Directorate for Social, Behavioral, and Economic Sciences as a case study and drawing on the new topic model of the NSF’s awards, this paper explores new methods for quantifying interdisciplinarity in the NSF portfolio.     

改进PSO算法结合FLANN在传感器动态建模中的应用

将改进的粒子群优化（PSO）算法和函数联接型神经网络(FLANN)相结合,实现传感器的动态线性建模。利用传感器的动态标定实验数据,首先训练FLANN神经网络,网络训练结束后的权值作为粒子群中某个粒子的初始值,而后利用改进的PSO算法继续寻优,得到的全局最优值即为所求的传感器动态模型的系数。实验结果表明,该方法结合了PSO和FLANN两者的优点,建模精度高。     

Analytical a priori approach to phase-plane modeling of SAR A/Dconverters

An analytical a priori approach to error modeling of successive approximation analog-to-digital converters (ADCs) is proposed. Errors are modeled as a function of both the output code and the time slope of the input signal. In particular, errors intrinsic to the algorithm of successive approximation in case of input signal time variation less than the least significant bit (LSB) during conversion are considered. The resulting differential nonlinearity is analytically related to the bit composition of the ADC output code bin. Analysis of errors intrinsic to the conversion algorithm makes the model general and application-independent. Moreover, the a priori approach makes its accurate identification easier. Numerical and experimental results of the model validation showing the effectiveness of the proposed approach are discussed     

A method for coupling the phase-field model based on a grand-potential formalism to thermodynamic databases

In this paper we derive an approach for the effective utilization of thermodynamic data in phase-field simulations. While the most widely used methodology for multi-component alloys is following the work by Eiken et al. (2006), wherein, an extrapolative scheme is utilized in conjunction with the TQ interface for deriving the driving force for phase transformation, a corresponding simplistic method based on the formulation of a parabolic free-energy model incorporating all the thermodynamics has been laid out for binary alloys in the work by Folch and Plapp (2005). In the following, we extend this latter approach for multi-component alloys in the framework of the grand-potential formalism. The coupling is applied for the case of the binary eutectic solidification in the Cr–Ni alloy and two-phase solidification in the ternary eutectic alloy (Al–Cr–Ni). A thermodynamic justification entails the basis of the formulation and places it in context of the bigger picture of Integrated Computational Materials Engineering.     

A two-scale approach for trabecular bone microstructure modeling based on computational homogenization procedure

In this paper the numerical implementation of two-scale modelling of bone microstructure is presented. The study is a part of long-term project on bone remodelling which drives bone microstructure change based directly on trabeculae surface energy. The proposed approach is based on a first-order computational homogenization technique. The coincidence of macro- and micro-model kinematics is done with the use of uniform displacement and traction boundary conditions. The computational homogenization procedure is driven by a self-prepared manager which is coded in Python. The computation on real bone structure (a piece of female Wistar rat bone) is performed as well.     

Extended thermodynamic approach to ion interaction chromatography

The chromatographic behavior of charged analytes in ion interaction chromatography (IIC) is theoretically investigated. The chemical modifications of the stationary and mobile phases in the presence of ion interaction reagent (IIR) are theoretically shown to change the partition coefficient for charged molecules. The most reliable literature experimental results concerning retention behavior of charged molecules in IIC were used to test the new theory. Retention equations are compared with those that can be obtained from the most important retention models in IIC. The present exhaustive retention model, which is well-founded in physical chemistry, goes further than the previous ones whose retention equations can be viewed as limiting cases of the present theory. The present extended thermodynamic approach reduces to stoichiometric or electrostatic retention models if the surface potential or pairing equilibria are respectively neglected. Moreover, it is able to quantitatively explain experimental evidences that cannot be rationalized by the existing retention models.     

Small atomic clusters on graphene: A model approach

Analytical expressions for the density of states for a dimer and two types of a trimer (a string and a triangle) are obtained using the M-model. All of the features of the adatoms that comprise the studied small clusters are shown to be defined by the fundamental properties of density of states of the graphene base.