Exploring polynomial based interpolation schemes for photoacoustic tomographic image reconstruction

Photoacoustic tomography (PAT) imaging employing polynomial-based interpolation methods is discussed. Nearest-neighbor, bilinear, bicubic and biquintic algorithms were implemented for the construction of the model matrix, and images were formed using the Tikhonov regularization and total variation (TV) minimization procedures. The performance of the interpolation methods was assessed by comparing the reconstructed images of three numerical and two experimental phantoms. The numerical and experimental studies demonstrate that the performance of the interpolation schemes is nearly equal for large PA sources. The simplest nearest-neighbor technique provides better image reconstruction for a sparse source compared to the others. The nearest-neighbor protocol may be adopted in practice for vascular imaging using PAT.

Wine Oligosaccharides: Underutilized or Irrelevant? A Study into the Effects of Oligosaccharides on Wine Taste and Mouthfeel

The taste and mouthfeel of a wine are two of the most important aspects of wine tasting. However, while much is known about phenolic compounds and other macromolecules direct effects on wine taste and mouthfeel, little is known about other wine compounds such as oligosaccharides. This experiment uses Fructo-oligosaccharide (FOS) and Galacto-oligosaccharide (GOS) at two different concentrations, 450 mg/L and 900 mg/L within a simple model wine matrix. A model matrix was used to control for any unknown interactions between oligosaccharides and the multitude of wine components. Oligosaccharides were added individually to the model wine matrix at each concentration to create four treatments. Triangle tests were performed on all treatments against the control base model wine and between the high and low concentrations of each oligosaccharide treatment. Following the triangle tests, each treatment and the control underwent descriptive analysis (DA) using line intensity scales for sweetness, bitterness, astringency, acidity, and viscosity. Triangle test results revealed a significant difference only between the FOS450 and FOS900 samples. The wine matrix was made more complicated by adding polyphenols and still, none of the four oligosaccharide treatment groups were found to be significantly different. DA found no significant differences for the five attributes but did show clear trends in increased sweetness and acidity, decreased bitterness, as well as changes to astringency and viscosity. This suggests there may be more complex interactions happening within the mouth. However, given the lack of significant results in the simple wine model and the more complex wine model wine, any complex interactions between oligosaccharides and other wine compounds are likely to be minimal.

An Ecosystem View of Peer-to-Peer Electricity Trading: Scenario Building by Business Model Matrix to Identify New Roles

This article introduces new roles in future peer-to-peer electricity trading markets. Following a qualitative approach, firstly, the value network of the current electricity market is presented. To do so, service streams, critical roles, activities, and their setting in the electricity market are identified. Secondly, in order to identify the main sources of uncertainty, the business model matrix framework is utilized to analyze peer-to-peer electricity trading. Thirdly, four future scenarios are built based on user involvement and customer ownership. The outcome of the scenario building is the emergence of new roles, brokers, and representatives in the future peer-to-peer electricity markets. Fourth, based on the four future scenarios, changes in the value network, new roles, and emerging/evolving activities are identified. Finally, the two new roles are discussed from grid structure, security and privacy, legal, and data protection perspectives. The data is gathered by conducting semi-structured interviews with stakeholders in the current electricity market as well as potential disruptors. This article elaborates on the configuration of the value network in the electricity market and highlights the changes that peer-to-peer trading imposes to the status quo. Through the outcomes of the value network analysis, it assists policy makers to consider the requirements and current market players to reconsider their business models.

The Collaborative Problem Based Learning Model Innovation

Learning models that can specifically support 21st-century skills which are fundamentals and global in nature, especially in higher education, are still not available. The Problem Based Learning (PBL) model and the Collaborative Learning (CL) model have characteristics that have the potential to support these skills. The purpose of the study is to develop a collaborative problem-based learning (CPBL) model. The study's results are five model syntaxes consisting of problem orientation, organization, collaborative problem solving, presentation and discussion, and evaluation. Besides, a model matrix was produced to guide lecturer and student learning activities to achieve fundamental and global 21st-century skills, namely problem solving, critical thinking, and collaboration. The syntaxes and matrix of the model produced are feasible, valid, and practically implemented to produce graduates who have ready and competitive skills. Thus, the developed CPBL model can become an innovative initial role model for learning to support learning at various levels, especially higher education, to produce graduates who have skills that are ready and competitive in the current era, maybe even in the future. Received: 18 March 2021 / Accepted: 21 May 2021 / Published: 8 July 2021

INFLUENCE OF MATRIX ERRORS ON PARAMETER ESTIMATES BY THE LEAST SQUARES METHOD

The paper investigates the effect of distorsions of the linear model matrix on the statistical characteristics of the least squares estimates.

A General Multipatch Model of Ebola Dynamics

A model for the transmission dynamics of Ebola virus in a multipatch network setting is studied. The model considers the contribution to the dynamics by people who are susceptible, infectious, isolated, deceased but still infectious and not yet buried, as well as the dynamics of the pathogen at interacting nodes or patches. Humans can move between patches carrying the disease to any patch in a region of n communities (patches). Both direct and indirect transmission are accounted for in this model. Matrix and graph-theoretic methods and some combinatorial identities are used to construct appropriate Lyapunov functions to establish global stability results for both the disease-free and the endemic equilibrium of the model. While the model is focused on Ebola, it can be adapted to the study of other disease epidemics, including COVID-19, currently affecting all countries in the world.

Development of the House of Quality for Rail Transportation Market

The article discusses the features and application of the technology of deployment of quality functions. The objective of the article is to present an efficient methodology allowing transport companies to make management decisions in the field of improving the quality of transport services provided to cargo owners. The technique was developed based on the House of Quality model (matrix) in the framework of the Total Quality Management (TQM) concept. Using logical, graphic, factorial, comparative, balance methods and considered technology the article describes in detail the structure and the procedure for constructing the House of Quality matrix within the process of analysis of rail transportation companies and focusing on the features and criteria of customer preferences in the field of rail freight transportation. Actual examples were used to show particularities of provision of rail transportation services. The developed technique and recommendations may be useful for transport companies to proceed with multiple factor analysis if their activity in the field of quality management, to assess efficacy and identify priorities while making decisions aimed at increasing quality of transportation services.