The smacof package offers a comprehensive implementation of multidimensional scaling (MDS) techniques in R. Since its first publication (De Leeuw and Mair 2009b) the functionality of the package has ...been enhanced, and several additional methods, features and utilities were added. Major updates include a complete re-implementation of multidimensional unfolding allowing for monotone dissimilarity transformations, including row-conditional, circular, and external unfolding. Additionally, the constrained MDS implementation was extended in terms of optimal scaling of the external variables. Further package additions include various tools and functions for goodness-of-fit assessment, unidimensional scaling, gravity MDS, asymmetric MDS, Procrustes, and MDS biplots. All these new package functionalities are illustrated using a variety of real-life applications.
While there is some recent empirical research on scale-ups, how digitalized start-ups transition to scale-up remains largely unexplored. Our research furthers our understanding of digitalized ...scale-ups and their growth process by examining how digitalized start-ups transform during scaling. We focus on internal workings of digitalized scale-ups and the transformation therein distinct from the firms' start-up phase. Drawing on firm growth literature, we use a qualitative methodology consisting of in-depth, semi-structured interviews with digitalized scale-up founders, finding commonality in their scaling process. We find scaling in digitalized firms is a complex mix of related internal activities, priorities, and trade-offs in pursuit of scaling process goals. Four priorities, goals, and related tensions relevant to their scaling process emerge from our analysis. We also find balancing tensions to optimize trade-offs require dynamic capabilities during scaling in digitalized firms. We conclude that although their growth patterns may be heterogeneous, digitalized scale-ups have commonality in their scaling process. The study furthers our understanding of the firm growth process and nascent literature specific to scaling digitalized firms, contributing towards a scaling process framework for digitalized scale-ups. We uncover opportunities to further develop theory, sharpening it with greater operative insight based on today's digitalized scale-ups.
•Digitalized scale-ups share commonality in scaling processes despite heterogeneity.•Scaling involves a complex mix of internal activities, priorities, and trade-offs.•Capacity building, process innovation and scale economics are prioritized.•In-depth interviews with scale-up founders inform a scaling process framework.•Explore founder learning agility and scaling process tensions in future research
Scaling methods in ecological modelling Fritsch, Matthias; Lischke, Heike; Meyer, Katrin M. ...
Methods in ecology and evolution,
November 2020, 2020-11-00, 20201101, Letnik:
11, Številka:
11
Journal Article
Recenzirano
Odprti dostop
Modelling is often confronted with scaling problems, because modelling—directly or indirectly—always implies scaling. This is because models simplify. Simplification usually means aggregation, and ...aggregation is a scaling process. As scaling cannot be avoided in modelling, it should carefully be addressed and resolved, at least to the degree possible.
In this paper, we give an overview of scaling approaches in ecological modelling. We propose to classify scaling approaches into pre‐model scaling, in‐model scaling and post‐model scaling depending on the timing of the scaling relative to the main modelling process.
We show general approaches, examples and potential application problems for each category. We suggest that scaling problems might be more widespread than previously thought. These scaling problems are matched with a range of solutions, but often these solutions will have to be adapted and tailored to the specific scaling case.
Thus, we recommend that ecologists be aware of scaling challenges especially where models do not explicitly aim at scaling. Developing general test systems for scaling methods may help to broaden and enhance the application of scaling methods in ecology.
Giving a detailed overview of the subject, this book takes in the results and methods that have arisen since the term 'self-organised criticality' was coined twenty years ago. Providing an overview ...of numerical and analytical methods, from their theoretical foundation to the actual application and implementation, the book is an easy access point to important results and sophisticated methods. Starting with the famous Bak-Tang-Wiesenfeld sandpile, ten key models are carefully defined, together with their results and applications. Comprehensive tables of numerical results are collected in one volume for the first time, making the information readily accessible to readers. Written for graduate students and practising researchers in a range of disciplines, from physics and mathematics to biology, sociology, finance, medicine and engineering, the book gives a practical, hands-on approach throughout. Methods and results are applied in ways that will relate to the reader's own research.
Inorganic scaling caused by precipitation of sparingly soluble salts at supersaturation is a common but critical issue, limiting the efficiency of membrane-based desalination and brine management ...technologies as well as other engineered systems. A wide range of minerals including calcium carbonate, calcium sulfate, and silica precipitate during membrane-based desalination, limiting water recovery and reducing process efficiency. The economic impact of scaling on desalination processes requires understanding of its sources, causes, effects, and control methods. In this Critical Review, we first describe nucleation mechanisms and crystal growth theories, which are fundamental to understanding inorganic scale formation during membrane desalination. We, then, discuss the key mechanisms and factors that govern membrane scaling, including membrane properties, such as surface roughness, charge, and functionality, as well as feedwater characteristics, such as pH, temperature, and ionic strength. We follow with a critical review of current characterization techniques for both homogeneous and heterogeneous nucleation, focusing on the strengths and limitations of each technique to elucidate scale-inducing mechanisms, observe actual crystal growth, and analyze the outcome of scaling behaviors of desalination membranes. We conclude with an outlook on research needs and future research directions to provide guidelines for scale mitigation in water treatment and desalination.
The nonlinear Hall effect has opened the door towards deeper understanding of topological states of matter. Disorder plays indispensable roles in various linear Hall effects, such as the localization ...in the quantized Hall effects and the extrinsic mechanisms of the anomalous, spin, and valley Hall effects. Unlike in the linear Hall effects, disorder enters the nonlinear Hall effect even in the leading order. Here, we derive the formulas of the nonlinear Hall conductivity in the presence of disorder scattering. We apply the formulas to calculate the nonlinear Hall response of the tilted 2D Dirac model, which is the symmetry-allowed minimal model for the nonlinear Hall effect and can serve as a building block in realistic band structures. More importantly, we construct the general scaling law of the nonlinear Hall effect, which may help in experiments to distinguish disorder-induced contributions to the nonlinear Hall effect in the future.
•Heat transfer in reactor core in LBLOCA scenario is analyzed with FSA method.•Scaling criteria and their importance are evaluated.•The priority of the criterion for convection heat transfer and heat ...accumulation is high.•The contribution of some initial and boundary conditions is too slight.
In integral test facilities, some phenomena relevant in the separate effect test are usually neglected due to scaling limitations and design compromises. The typical heat transfer phenomenon in reactor core in large break loss of coolant accident (LBLOCA) scenario is analyzed with fractional scaling analysis (FSA) method in this work. A conservation form of cladding temperature is derived on the basis of energy conservation. Then the scaling criteria and their importance are evaluated. It is found that the similarities of the criteria for convection heat transfer and heat accumulation should be guaranteed since their priorities are high. The contribution of initial pressure and distribution of coolant inventory to cladding temperature in LBLOCA scenario is too slight. This work is encouraging and may shed a light on the coupling application of hierarchical two-tiered scaling (H2TS) and FSA method in engineering application.
An energy independent scaling of the near-side ridge yield at a given multiplicity has been observed by the ATLAS and the CMS collaborations in p+p collisions at s=7 and 13 TeV. Such a striking ...feature of the data can be successfully explained by approaches based on initial state momentum space correlation generated due to gluon saturation. In this paper, we try to examine if such a scaling is also an inherent feature of the approaches that employ strong final state interaction in p+p collisions. We find that hydrodynamical modeling of p+p collisions using EPOS 3 shows a violation of such scaling. The current study can, therefore, provide important new insights on the origin of long-range azimuthal correlations in high multiplicity p+p collisions at the LHC energies.
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