Comminution of Logging Residues with Evolution 910R chipper, MOHA chipper truck, and Morbark 1200 tub grinder

This study is part of the ongoing national Bioenergy Research Programme in Finland. The study looked into the quality of chips made of logging residues composed predominantly of spruce wood. In addition, the productivity of the Evolution 910R chipper, the MOHA chipper truck, and the Morbark 1200 tub grinder was studied. The three machines studied were capable of producing acceptable chips for heat generation plants. The particle-size distribution was good in all cases and the proportion of large particles and the fine fraction was small. The ash content of the chips was low due to carefulness in the handling of logging residues. The moisture content was typical for logging residues stored at the logging site for some months. The machine productivity values obtained were as follows: Evolution = 65 m3 loose/E15-h, MOHA = 23 m3 loose/E15-h, and Morbark = 5060 m3 loose/E15-h. These results are preliminary; a follow-up study is needed for more reliable results to be obtained concerning the productivities

User Participation in Consulting Projects: Client and Provider Role Variations

This study presents a variation scheme of participation roles in consulting projects. Typical consulting assignments in the area known as IS planning involve strategic planning and information systems management, enterprise architecture, information management or information technology governance. Participation is a crucial issue in consulting on these issues. In the literature on participation, different roles and tasks have been found, but it is not always specified, on what types of projects or systems the results are based. The literature on consulting suggests some models for work division. In a two-phase qualitative study, we first collect possible tasks in ICT consulting projects, and then, based on further explorations, create a model for role variations in consulting. We compare roles suggested in the literature on participation and on consulting to our findings. The suggested variation model gives a common framework of reference for negotiations between the provider and the client, and helps to anticipate the needed competences and resources from both parties, and discern between their responsibilities

Effects of solar wind magnetosphere coupling recorded at different geomagnetic latitudes: Separation of directly-driven and storage/release systems

The effect on geomagnetic activity of solar wind speed, compared with that of the strength of the interplanetary magnetic field, differs with geomagnetic latitude. In this study we construct a new index based on monthly standard deviations in the H-component of the geomagnetic field for all geomagnetic latitudes. We demonstrate that for this index the response at auroral regions correlates best with interplanetary coupling functions which include the solar wind speed while mid- and low-latitude regions respond to variations in the interplanetary magnetic field strength. These results are used to isolate the responsible geomagnetic current systems

Relation between substorm characteristics and rapid temporal variations of the ground magnetic field

Auroral substorms are one of the major causes of large geomagnetically induced currents (GIC) in technological systems. This study deals with different phases of the auroral substorm concerning their severity from the GIC viewpoint. Our database consists of 833 substorms observed by the IMAGE magnetometer network in 1997 (around sunspot minimum) and 1999 (rising phase of the sunspot cycle), divided into two classes according to the <i>D<sub>st</sub></i> index: non-storm (<i>D<sub>st</sub></i>>-40 nT, 696 events) and storm-time ones (<i>D<sub>st</sub></i><-40 nT, 137 events). The key quantity concerning GIC is the time derivative of the horizontal magnetic field vector (<i>d</i><i><b>H</b></i>/<i>dt</i>) whose largest values during substorms occur most probably at about 5 min after the onset at stations with CGM latitude less than 72 deg. When looking at the median time of the occurrence of the maximum <i>d</i><i><b>H</b></i>/<i>dt</i> after the expansion onset, it increases as a function of latitude from about 15 min at CGM lat=56 deg to about 45 min at CGM lat=75 deg for non-storm substorms. For storm-time events, these times are about 5 min longer. Based on calculated ionospheric equivalent currents, large <i>d</i><i><b>H</b></i>/<i>dt</i> occur mostly during the substorm onset when the amplitude of the westward electrojet increases rapidly

Bayesian approach to image reconstruction in photoacoustic tomography

Photoacoustic tomography is a hybrid imaging method that has a variety of biomedical applications. In photoacoustic tomography, the image reconstruction problem (inverse problem) is to resolve the initial pressure distribution from detected ultrasound waves generated within an object due to an illumination of a short light pulse. In this work, this problem is approached in Bayesian framework. Image reconstruction is investigated with numerical simulations in different detector geometries, including limited view setup, and utilizing different prior information. Furthermore, assessing the reliability of the estimates is investigated. The simulations show that the Bayesian approach can produce accurate estimates of the initial pressure distribution and uncertainty information even in a limited view setup if proper prior information is utilized

Modelling of errors due to speed of sound variations in photoacoustic tomography using a Bayesian framework

Inverse problem of estimating initial pressure in photoacoustic tomography is ill-posed and thus sensitive to errors in modelling and measurements. In practical experiments, accurate knowledge of the speed of sound of the imaged target is commonly not available, and therefore an approximate speed of sound is used in the computational model. This can result in errors in the solution of the inverse problem that can appear as artefacts in the reconstructed images. In this paper, the inverse problem of photoacoustic tomography is approached in a Bayesian framework. Errors due to uncertainties in the speed of sound are modelled using Bayesian approximation error modelling. Estimation of the initial pressure distribution together with information on the reliability of these estimates are considered. The approach was studied using numerical simulations. The results show that uncertainties in the speed of sound can cause significant errors in the solution of the inverse problem. However, modelling of these uncertainties improves the accuracy of the solution

ValoMC: a Monte Carlo software and MATLAB toolbox for simulating light transport in biological tissue

A Monte Carlo method for photon transport has gained wide popularity in biomedical optics for studying light behaviour in tissue. Nowadays, typical computation times range from a few minutes to hours. Although various implementations of the Monte Carlo algorithm exist, there is only a limited number of free software available. In addition, these packages may require substantial learning efforts. To address these issues, we present a new Monte Carlo software with a user-friendly interface. The simulation geometry is defined using an unstructured (triangular or tetrahedral) mesh. The program solves the photon fluence in the computation domain and the exitance at the domain boundary. It is capable of simulating complex measurement geometries with spatially varying optical parameter distributions and supports several types of light sources as well as intensity modulated light. Furthermore, attention is given to ease of use and fast problem set up with a MATLAB (The MathWorks Inc., Natick, MA) interface. The simulation code is written in C++ and parallelized using OpenMP. The simulation code has been validated against analytical and numerical solutions of radiative transfer equation and other Monte Carlo software in good agreement. The software is available for download from the homepage https://inverselight.github.io/ValoMC/ and the source code from GitHub https://github.com/InverseLight/ValoMC