Hybrid paper-based microfluidics: combination of paper-based analytical device (µPAD) and digital microfluidics (DMF) on a single substrate

Microfluidics found its place in point of care diagnostics. Microfluidic devices on paper substrate are proposed on both channel-based and digital microfluidics (DMF). But fluid flow controlling on microfluidics paper-based analytical devices (µPADs) and post-processing on DMF devices have limitations. In this work a new hybrid paper-based device is proposed with the aim of resolving these limitations and expanding the microfluidics capabilities in point of care diagnostics. The hybrid paper-based microfluidics (HPMF) device is composed of a DMF device following a µPAD in a single substrate, in which the DMF part performs the preprocessing steps of the test on droplets and transfers the resulting droplet to the µPAD part of the device for post-processing steps. The fabrication process of the device is rapid and very low cost due to use of paper substrate and out of clean-room processes. The results show that the proposed HPMF device can perform droplet operations: moving, mixing, and splitting.     

A versatile technology platform for microfluidic handling systems,part I: fabrication and functionalization

Many microfluidic devices are made using specialized fabrication processes, limiting the ability to integrate those devices on the same chip. In this paper, a versatile technology platform is presented that allows for integration of many different devices. It provides a method to design channels in a wide range of sizes and shapes with different functionalization options in close proximity to the fluid in the channels. The latter includes release of the channels for thermal isolation or mechanical movement and metal or piezoelectric layers for actuation and read-out. The channel walls are made using silicon-rich silicon nitride to provide durable, strong, chemically inert and thermally stable channels directly below the substrate surface .     

EPSILON: a versatile microcomputer program for the spectrophotometric data analysis of metal–ligand equilibria

We have developed the microcomputer program EPSILON which allows the computation of equilibrium constants and extinction coefficients of several interacting species from spectrophotometric single- and multi-wavelength pH-titration data. Novel features of EPSILON include: easy treatment of the data through a windowed environment, minimization of errors with respect to the read variable (absorbance), simultaneous plotting of both the spectrophotometric titration curve and the species distribution as a function of pH during refinement and estimation of standard deviations for the refined parameters. Several examples of applications are provided and discussed in order to illustrate the use of EPSILON. The results are compared with literature values and with those obtained by BEST from potentiometric data.     

“Plug-up”–a new concept for fabricating SOI MEMS devices

This paper reports a novel process sequence for fabricating micromechanical devices on silicon-on-insulator (SOI) wafers. Among the merits of the described process are its improved immunity to stiction and elimination of conductor metal endurance problems during sacrificial etching in hydrofluoric acid. With this novel process one can controllably embed vacuum cavities within SOI substrates. Further processing of such cavity wafers enables realization of a wide variety of micromechanical devices based on single crystalline silicon or even integrated read-out circuitry.K. Järvi and T. Häkkinen are gratefully acknowledged for the device fabrication. The Finnish National Technology Agency, Okmetic, VTI Technologies, and Micro Analog Systems participated in funding this work. The ultrasonic devices were fabricated in collaboration with Autotank, Oras, Suunto, Vaisala, and Enermet.     

Discretization methods with analytical solutions for a convection–reaction equation with higher-order discretizations

We introduce an improved second-order discretization method for the convection–reaction equation by combining analytical and numerical solutions. The method is derived from Godunov's scheme, see [S.K. Godunov, Difference methods for the numerical calculations of discontinuous solutions of the equations of fluid dynamics, Mat. Sb. 47 (1959), pp. 271–306] and [R.J. LeVeque, Finite Volume Methods for Hyperbolic Problems, Cambridge Texts in Applied Mathematics, Cambridge University Press, 2002.], and uses analytical solutions to solve the one-dimensional convection-reaction equation. We can also generalize the second-order methods for discontinuous solutions, because of the analytical test functions. One-dimensional solutions are used in the higher-dimensional solution of the numerical method.

The method is based on the flux-based characteristic methods and is an attractive alternative to the classical higher-order total variation diminishing methods, see [A. Harten, High resolution schemes for hyperbolic conservation laws, J. Comput. Phys. 49 (1993), pp. 357–393.]. In this article, we will focus on the derivation of analytical solutions embedded into a finite volume method, for general and special solutions of the characteristic methods.

For the analytical solution, we use the Laplace transformation to reduce the equation to an ordinary differential equation. With general initial conditions, e.g. spline functions, the Laplace transformation is accomplished with the help of numerical methods. The proposed discretization method skips the classical error between the convection and reaction equation by using the operator-splitting method.

At the end of the article, we illustrate the higher-order method for different benchmark problems. Finally, the method is shown to produce realistic results.     

“Andromaly”: a behavioral malware detection framework for android devices

This article presents Andromaly—a framework for detecting malware on Android mobile devices. The proposed framework realizes a Host-based Malware Detection System that continuously monitors various features and events obtained from the mobile device and then applies Machine Learning anomaly detectors to classify the collected data as normal (benign) or abnormal (malicious). Since no malicious applications are yet available for Android, we developed four malicious applications, and evaluated Andromaly’s ability to detect new malware based on samples of known malware. We evaluated several combinations of anomaly detection algorithms, feature selection method and the number of top features in order to find the combination that yields the best performance in detecting new malware on Android. Empirical results suggest that the proposed framework is effective in detecting malware on mobile devices in general and on Android in particular.     

iTalk–iSee: A participatory visual learning analytical tool for productive peer talk

International Journal of Computer-Supported Collaborative Learning - Productive peer talk moves have a fundamental role in structuring group discussions and promoting peer interactions. However,...     

A new hybrid method for time series forecasting: AR–ANFIS

In this study, a new hybrid forecasting method is proposed. The proposed method is called autoregressive adaptive network fuzzy inference system (AR–ANFIS). AR–ANFIS can be shown in a network structure. The architecture of the network has two parts. The first part is an ANFIS structure and the second part is a linear AR model structure. In the literature, AR models and ANFIS are widely used in time series forecasting. Linear AR models are used according to model-based strategy. A nonlinear model is employed by using ANFIS. Moreover, ANFIS is a kind of data-based modeling system like artificial neural network. In this study, a linear and nonlinear forecasting model is proposed by creating a hybrid method of AR and ANFIS. The new method has advantages of data-based and model-based approaches. AR–ANFIS is trained by using particle swarm optimization, and fuzzification is done by using fuzzy C-Means method. AR–ANFIS method is examined on some real-life time series data, and it is compared with the other time series forecasting methods. As a consequence of applications, it is shown that the proposed method can produce accurate forecasts.

     

Application of nonlocal strain–stress gradient theory and GDQEM for thermo-vibration responses of a laminated composite nanoshell

In this article, thermal buckling and frequency analysis of a size-dependent laminated composite cylindrical nanoshell in thermal environment using nonlocal strain–stress gradient theory are presented. The thermodynamic equations of the laminated cylindrical nanoshell are based on first-order shear deformation theory, and generalized differential quadrature element method is implemented to solve these equations and obtain natural frequency and critical temperature of the presented model. The results show that by considering C–F boundary conditions and every even layers’ number, in lower value of length scale parameter, by increasing the length scale parameter, the frequency of the structure decreases but in higher value of length scale parameter this matter is inverse. Finally, influences of temperature difference, ply angle, length scale and nonlocal parameters on the critical temperature and frequency of the laminated composite nanostructure are investigated.

     

The space–time CESE scheme for shallow water equations incorporating variable bottom topography and horizontal temperature gradients

The effects of bottom topography and horizontal temperature gradients on the shallow water flows are theoretically investigated. The considered systems of partial differential equations (PDEs) are non-strictly hyperbolic and non-conservative due to the presence of non-conservative differential terms on the right hand side. The solutions of these model equations are very challenging for a numerical scheme. Thus, our primary goal is to introduce an improved numerical scheme which can handle the non-conservative differential terms efficiently and accurately. In this paper, the space–time conservation element and solution element (CESE) method is extended to approximate these model equations. The proposed scheme has capability to overcome all difficulties posed by this nonlinear system of PDEs. The performance of the scheme is analyzed by considering several case studies of practical interest and the results of suggested scheme are compared with those of central NT scheme. The accuracy of the scheme is verified qualitatively and quantitatively.     

Operational semantics of a domain specific language for real time musician–computer interaction

With the advent and availability of powerful personal computing, the computer music research and industry have been focusing on real-time musical interactions between musicians and computers; delegating human-like actions to computers who interact with a musical environment. One common use-case of this kind is Automatic Accompaniment where the system is comprised of a real-time machine listening system that in reaction to recognition of events in a score from a human performer, launches necessary actions for the accompaniment section. While the real-time detection of score events out of live musicians’ performance has been widely addressed in the literature, score accompaniment (or the reactive part of the process) has been rarely discussed. This paper deals with this missing component in the literature from a formal language perspective. We show how language considerations would enable better authoring of time and interaction during programming/composing and how it addresses critical aspects of a musical performance (such as errors) in real-time. We sketch the real-time features required by automatic musical accompaniment seen as a reactive system. We formalize the timing strategies for musical events taking into account the various temporal scales used in music. Various strategies for the handling of synchronization constraints and the handling of errors are presented. We give a formal semantics to model the possible behaviors of the system in terms of Parametric Timed Automata.     

Tapping into the wealth of employees’ ideas: Design principles for a digital intrapreneurship platform

Digital transformation offers organizations opportunities to involve intrapreneurs, i.e., employees sharing the zeal of entrepreneurs, but innovating within organizational boundaries through the generation of new ideas. Despite organizations’ interest in exploiting their employees’ innovation potential, tools as digital intrapreneurship platforms guiding and hosting this innovation process are limited and their design is challenging. Thus, we provide the results of an action design research project with an IT service provider and describe the iterative design process. The designed intrapreneurship platform is ingrained in the socio-technical system theory. Its evaluation derives design principles, guiding organizations to design viable platforms facilitating intrapreneurial behavior.     

The EM algorithm in a distributed computing environment for modelling environmental space–time data

Statistical models for spatio-temporal data are increasingly used in environmetrics, climate change, epidemiology, remote sensing and dynamical risk mapping. Due to the complexity of the relationships among the involved variables and dimensionality of the parameter set to be estimated, techniques for model definition and estimation which can be worked out stepwise are welcome. In this context, hierarchical models are a suitable solution since they make it possible to define the joint dynamics and the full likelihood starting from simpler conditional submodels. Moreover, for a large class of hierarchical models, the maximum likelihood estimation procedure can be simplified using the Expectation–Maximization (EM) algorithm.In this paper, we define the EM algorithm for a rather general three-stage spatio-temporal hierarchical model, which includes also spatio-temporal covariates. In particular, we show that most of the parameters are updated using closed forms and this guarantees stability of the algorithm unlike the classical optimization techniques of the Newton–Raphson type for maximizing the full likelihood function. Moreover, we illustrate how the EM algorithm can be combined with a spatio-temporal parametric bootstrap for evaluating the parameter accuracy through standard errors and non-Gaussian confidence intervals.To do this a new software library in form of a standard R package has been developed. Moreover, realistic simulations on a distributed computing environment allow us to discuss the algorithm properties and performance also in terms of convergence iterations and computing times.     

Developing a streaming data processing workflow for querying space–time activities from geotagged tweets

The critical dimensions in describing space–time activities are “what“, “where”, “when”, and “who”, which are frequently applied to collect data about basic functions people perform in space in the course of a day. Collecting data about these dimensions using activity-based surveys has presented researchers with a number of technical and social limitations, ranging from the restricted period of time participants have to record their activities to the level of accuracy with which participants complete a survey. This paper proposes a new streaming data processing workflow for querying space–time activities (STA) as a by-product of microblogging communication. It allows exploring a large volume of geotagged tweets to discover STA patterns of daily life in a systematic manner. A sequence of tasks have been implemented using different cloud-based computing resources for handling over one million of daily geotagged tweets from Canada for a period of six months. The STA patterns have revealed activity choices that might be attributable to personal motivations for communicating an activity in social networks.     

Periodic solutions for a delayed predator–prey system with stage-structured predator on time scales

In this paper, a modified delayed predator–prey system with stage structure for predator is proposed and studied, which generalizes and incorporates as special cases some known models. With the help of continuation theorem based on the Gaines and Mawhin coincidence degree theory, we investigate the existence of periodic solutions for the proposed delayed predator–prey system with stage-structured predator and two kinds of functional responses (called Holling III functional response and Beddington–DeAngelis functional response) on time scales. In particular, when the time scale is chosen as the set of the real numbers or the integers, the existence of the periodic solutions of the corresponding continuous-time and discrete-time models follows.     

On a Petrov–Galerkin method for the electrical and thermal behaviour of semiconductor devices in two dimensions

We consider the equations governing the electrical and thermal behaviour of a semiconductor device in two dimensions. A non-standard Petrov-Galerkin method is used to obtain a discretisation of the equations for stationary problems. The resulting scheme is a generalization to the two-dimensional case and to the full set of equations of the well-known Scharfetter-Gummel scheme, which is the most successful discretisation for one-dimensional problems. The dependent variables used are the carrier densities, the electrostatic potential and the absolute temperature.     

SERP-test: a taxonomy for supporting industry–academia communication

This paper presents the construction and evaluation of SERP-test, a taxonomy aimed to improve communication between researchers and practitioners in the area of software testing. SERP-test can be utilized for direct communication in industry academia collaborations. It may also facilitate indirect communication between practitioners adopting software engineering research and researchers who are striving for industry relevance. SERP-test was constructed through a systematic and goal-oriented approach which included literature reviews and interviews with practitioners and researchers. SERP-test was evaluated through an online survey and by utilizing it in an industry–academia collaboration project. SERP-test comprises four facets along which both research contributions and practical challenges may be classified: Intervention, Scope, Effect target and Context constraints. This paper explains the available categories for each of these facets (i.e., their definitions and rationales) and presents examples of categorized entities. Several tasks may benefit from SERP-test, such as formulating research goals from a problem perspective, describing practical challenges in a researchable fashion, analyzing primary studies in a literature review, or identifying relevant points of comparison and generalization of research.