We survey literature on mobile money and its contribution in promoting financial inclusion and development, with a focus on sub-Saharan Africa. We use taxonomic, descriptive and analytical methods to evaluate the state of knowledge in the area. We analyse how mobile technology in general may contribute to economic development and financial inclusion in theory and practise. We explain the mechanics of mobile money using Kenya’s M-Pesa as a canonical example; and consider whether the literature has fully established the potential economic impact of mobile money especially its contribution to financial inclusion. We also consider market structure, pricing and regulatory implications of mobile money. We conclude by highlighting issues that require further investigation: the take-up of mobile money; mobile money and financial inclusion; substitutability between mobile money and conventional finance; and regulatory structures for institutions providing mobile money services.
ABSTRACT In the framework of the Cost Action CERTBOND (Reliable roadmap for certification of bonded primary structures), a wide group of researchers from 27 European Countries have had the opportunity to work on the topic of certification of bonded joints for primary structural applications from different engineering sectors such as the aerospace, automotive, civil engineering, wind energy and marine sectors. Since virtual testing and optimization are basic tools in the certification process, one of the key objectives of CERTBOND is to critically review some of the available models and failure theories for adhesive joints. The present paper summarizes the outcome of this task. Nine different models/theories are described in detail. Specifically, reviewed are the Classical Analytical Methods, the Process Zone Methods, Linear Elastic Fracture Mechanics (LEFM), the Virtual Crack Closure Technique (VCCT), the Stress Singularity Approach, Finite Fracture Mechanics (FFM), the Cohesive Zone Method (CZM), the Progressive Damage Modeling method and the Probabilistic methods. Also, at the end of the paper, the modeling of temperature effects on adhesive joints have been addressed. For each model/theory, information on the methodology, the required input, the main results, the advantages and disadvantages and the applications are given.
Nikolay Bobev, Pieter Bomans, Friðrik Freyr Gautason
Abstract We study the maximally supersymmetric Yang-Mills theory on S d using supersymmetric localisation and holography. We argue that the analytic continuation in dimension to d = 1 yields a Euclidean version of the BMN matrix quantum mechanics. This system can be analysed at large N using supersymmetric localisation and leads to explicit results for the free energy on S d and the expectation value of supersymmetric Wilson loops. We show how these results can be reproduced at strong gauge coupling using holography by employing spherical D-brane solutions. We construct these solutions for any value of d using an effective supergravity description and pay particular attention to the subtleties arising in the d → 1 limit. Our results have implications for the BMN matrix quantum mechanics and the physics of circular D0-branes.
Nuclear and particle physics. Atomic energy. Radioactivity
Lars Kool, Jules Tampier, Philippe Bourrianne
et al.
Flows of particles through bottlenecks are ubiquitous in nature and industry, involving both dry granular materials and suspensions. However, difficulties in precisely controlling particle properties in conventional set-ups hinder the full understanding of these flows in confined geometries. Here, we present a microfluidic model set-up to investigate the flow of dense suspensions in a two-dimensional hopper channel. Particles with controlled properties such as shape and deformability are in situ fabricated with a photolithographic projection method and compacted at the channel constriction using a Quake valve. The set-up is characterised by examining the flow of a dense suspension of hard, monodisperse disks through constrictions of varying widths. We demonstrate that the microfluidic hopper discharges particles at a constant rate under both imposed pressure and flow rate. The discharge of particles under imposed flow rate follows a Beverloo-like scaling, while it varies nonlinearly with particle size under imposed pressure. Additionally, we show that the statistics of clog formation in our microfluidic hopper follow the same stochastic laws as reported in other systems. Finally, we show how the versatility of our microfluidic model system can be used to investigate the outflow and clogging of suspensions of more complex particles.
Vedasri Godavarthi, Kartik Krishna, Steven L. Brunton
et al.
Biological flyers and swimmers navigate in unsteady wake flows using limited sensory abilities and actuation energies. Understanding how vortical structures can be leveraged for energy-efficient navigation in unsteady flows is beneficial in developing autonomous navigation for small-scale aerial and marine vehicles. Such vehicles are typically operated with constrained onboard actuation and sensing capabilities, making energy-efficient trajectory planning critically important. This study finds that trajectory planners can leverage three-dimensionality appearing in a complex unsteady wake for efficient navigation using limited flowfield information. This is revealed with comprehensive investigations by finite-horizon model-predictive control for trajectory planning of a swimmer behind a cylinder wake at Reynolds number of 300. The navigation performance of three-dimensional cases is compared with scenarios in a two-dimensional (2-D) wake. The underactuated swimmer is able to reach the target by leveraging the background flow when the prediction horizon exceeds one-tenth of the wake-shedding period, demonstrating that navigation is feasible with limited information about the flowfield. Further, we identify that the swimmer can leverage the secondary transverse vortical structures to reach the target faster than is achievable navigating in a 2-D wake.
We present an exploratory method for discovering likely misconceptions from multiple-choice concept test data, as well as preliminary evidence that this method recovers known misconceptions from real student responses. Our procedure is based on a Bayesian implementation of the Multidimensional Nominal Categories IRT model (MNCM) combined with standard factor-analytic rotation methods; by analyzing student responses at the level of individual distractors rather than at the level of entire questions, this approach is able to highlight multiple likely misconceptions for subsequent investigation without requiring any manual labeling of test content. We explore the performance of the Bayesian MNCM on synthetic data and find that it is able to recover multidimensional item parameters consistently at achievable sample sizes. These studies demonstrate the method's robustness to overfitting and ability to perform automatic dimensionality assessment and selection. The method also compares favorably to existing IRT software implementing marginal maximum likelihood estimation which we use as a validation benchmark. We then apply our method to approximately 10,000 students' responses to a research-designed concept test: the Force Concept Inventory. In addition to a broad first dimension strongly correlated with overall test score, we discover thirteen additional dimensions which load on smaller sets of distractors; we discuss two as examples, showing that these are consistent with already-known misconceptions in Newtonian mechanics. While work remains to validate our findings, our hope is that future applications of this method could aid in the refinement of existing concept inventories or the development of new ones, enable the discovery of previously-unknown student misconceptions across a variety of disciplines, and—by leveraging the method's ability to quantify the prevalence of particular misconceptions—provide opportunities for targeted instruction at both the individual and classroom level.
This paper addresses the approximation of a bounded (on the entire real axis) solution of a linear ordinary differential equation, where the matrix approaches zero as t →∓∞ and the right-hand side is bounded with a weight. We construct regular two-point boundary value problems to approximate the original problem, assuming the matrix and the right-hand side, both weighted, are constant in the limit. An approximation estimate is provided. The relationship between the well-posedness of the singular boundary value problem and the well-posedness of an approximating regular problem is established.
In this study, the time-dependent source identification problem for the two-dimensional neutron transport equation was studied. For the approximate solution of this problem a first order of accuracy difference scheme was presented. Stability estimates for the solution of these differential and difference problems were established. Numerical results were given.
We investigate a system of linear ordinary differential equations containing point and integral loadings with nonlocal boundary conditions. Boundary conditions include integral and point values of the unknown function. An essential feature of the problem is that the kernels of the integral terms in the differential equations depend only on the integration variable. It is shown that similar problems arise during feedback control of objects with both lumped and distributed parameters during point and integral measurements of the current state for the controllable object. The problem statement considered in the paper generalizes a lot of previously studied problems regarding loaded differential equations with nonlocal boundary conditions. By introducing auxiliary parameters, we obtain necessary conditions for the existence and uniqueness of a solution to the problem under consideration. To solve the problem numerically, we propose to use a representation of the solution to the original problem, which includes four matrix functions that are solutions to four auxiliary Cauchy problems. Using solutions to the auxiliary problems in boundary conditions, we obtain the values of the unknown function at the loading points. This is enough to get the desired solution. The paper describes the application of the method using the example of solving a test model problem.
The paper considers Morrey-type local spaces from LM^w_pθ. The main work is the proof of the commutator compactness theorem for the Riesz potential [b, I_α] in local Morrey-type spaces from LM^w1_pθ to LM^w2_qθ. We also give new sufficient conditions for the commutator to be bounded for the Riesz potential [b, I_α] in local Morrey-type spaces from LM^w1_pθ to LM^w2_qθ. In the proof of the commutator compactness theorem for the Riesz potential, we essentially use the boundedness condition for the commutator for the Riesz potential [b, Iα] in local Morrey-type spaces LM^w_pθ, and use the sufficient conditions from the theorem of precompactness of sets in local spaces of Morrey type LM^w_pθ. In the course of proving the commutator compactness theorem for the Riesz potential, we prove lemmas for the commutator ball for the Riesz potential [b, I_α]. Similar results were obtained for global Morrey-type spaces GM^w_pθ and for generalized Morrey spaces M^w_p.
The article is devoted to the study of semantic Jonsson quasivarieties of universal unars and undirected graphs. The first section of the article consists of basic necessary concepts from Jonsson model theory. The following two sections are results of using new notions of semantic Jonsson quasivariety of Robinson unars JCU and semantic Jonsson quasivariety of Robinson undirected graphs JCG, its elementary theory and semantic model. In order to prove two main results of the paper, Robinson spectra RSp(JCU) and RSp(JCG) and their partition onto equivalence classes [∆]U and [∆]G by cosemanticness relation were considered. The main results are presented in the form of theorems 11 and 13 and imply following useful corollaries: countably categorical Robinson theories of unars are totally categorical; countably categorical Robinson theories of undirected graphs are totally categorical. The obtained results can be useful for continuation of the various Jonsson algebras’ research, particularly semantic Jonsson quasivariety of S-acts over cyclic monoid.
In this paper, we describe the advances in the design, actuation, modeling, and control field of continuum robots. After decades of pioneering research, many innovative structural design and actuation methods have arisen. Untethered magnetic robots are a good example; its external actuation characteristic allows for miniaturization, and they have gotten a lot of interest from academics. Furthermore, continuum robots with proprioceptive abilities are also studied. In modeling, modeling approaches based on continuum mechanics and geometric shaping hypothesis have made significant progress after years of research. Geometric exact continuum mechanics yields apparent computing efficiency via discrete modeling when combined with numerical analytic methods such that many effective model-based control methods have been realized. In the control, closed-loop and hybrid control methods offer great accuracy and resilience of motion control when combined with sensor feedback information. On the other hand, the advancement of machine learning has made modeling and control of continuum robots easier. The data-driven modeling technique simplifies modeling and improves anti-interference and generalization abilities. This paper discusses the current development and challenges of continuum robots in the above fields and provides prospects for the future.
In this paper we consider a boundary value problem for a fractionally loaded heat equation in the class of continuous functions. Research methods are based on an approach to the study of boundary value problems, based on their reduction to integral equations. The problem is reduced to a Volterra integral equation of the second kind by inverting the differential part. We also carried out a study the limit cases for the fractional derivative order of the term with a load in the heat equation of the boundary value problem. It is shown that the existence and uniqueness of solutions to the integral equation depends on the order of the fractional derivative in the loaded term.
In the theory of one-dimensional trigonometric series, the Hardy-Littlewood theorem on Fourier series with monotone Fourier coefficients is of great importance. Multidimensional versions of this theorem have been extensively studied for the Lebesgue space. Significant differences of the multidimensional variants in comparison with the one-dimensional case are revealed and the strengthening of this theorem is obtained. The Hardy-Littlewood theorem is also generalized for various function spaces and various types of monotonicity of the series coefficients. Some of these generalizations can be seen in works of M.F. Timan, M.I. Dyachenko, E.D. Nursultanov, S. Tikhonov. In this paper, a generalization of the Hardy-Littlewood theorem for double Fourier series of a function in the space Lqϕ(Lq)(0,2π]2 is obtained.
In this work, the solvability of the problem with Neumann and Dirichlet boundary conditions for the Gellerstedt equation in four variables is investigated. The energy integral method is used to prove the uniqueness of the solution to the problem. In addition to it, formulas for differentiation, autotransformation, and decomposition of hypergeometric functions are applied. The solution is obtained explicitly and is expressed by Lauricella’s hypergeometric function.