Sensitivity of blood flow dynamics simulations in the pulmonary arteries to inflow boundary conditions

The Pulmonary Artery (PA) is an important part of the cardiovascular system. The PA drives the oxygenation of blood by transporting it from the Right Ventricle (RV) to the lungs. Blood flow first go through the Main Pulmonary Artery (MPA) and then splits into the Right Pulmonary Artery (RPA) and the Left Pulmonary Artery (LPA), which divides into smaller vessels inside the human lungs. The blood flow in the PA have biological and mechanical characteristics that are sensitive to physiological and anatomical changes. The objective of this study is to understand the sensitivity of the flow patterns to the inflow boundary condition using a combination of in-vivo data and Computational Fluid Dynamics (CFD). A population of N = 35 subjects (reduced to 28 after analysis) composed of healthy adults is considered for this study. Geometries are extracted from magnetic resonance imaging (MRI), and velocity fields from corresponding 4D flow data. Numerical simulations are conducted on an cohort-averaged shape using the software SimVascular. Inlet conditions consist of an average velocity profile (obtained from the mean of the patient-specific in-vivo velocity data); sensitivity is studied superimposing a fraction of the standard deviation. Results were post-processed in the open-source software ParaView. The inlet profile showed significant variations across the cohort. Accordingly, flow patterns demonstrated a non-negligible sensitivity to inflow conditions in terms of flow topology and overall characteristics. The results emphasize the importance of using patient-specific boundary conditions for reliable simulations of blood flow in the pulmonary arteries.Incomin

Evolution of acoustic waves in heaped granular material

The propagation and structure of acoustic finite amplitude wave in heaped granular material is studied in this paper. The equations describing the evolution of arbitrary wave disturbances of finite amplitude velocity (density, or temperature) perturbations have been developed, with correction for heat transfer and momentum exchange between the phases under significantly unsteady conditions. The extreme cases of long- and short-wave interactions between phases are obtained. The resulting equations incorporate integral terms containing the amplitude of the perturbation. These formulae are valid for describing the evolution of waves at any ratio between the time of the internal process and the characteristic period of perturbation. Because of the high interaction between the skeleton and internal gas, the finite amplitude wave is largely dissipative. It will be shown that during the wave propagation, decrease of the wave amplitude with increasing distance is described by an exponential curve

Asylum diversity in the European Union: A case study of residence permit distribution to asylum seekers in Sweden and Finland

The ongoing refugee crisis has divided the European Union. While some states shelter hundreds of thousands of refugees, others only grant asylum to a handful. This phenomenon is creating a demographic rift inside the union and is also causing internal quarrels over joint responsibility, which possibly could undermine the existence of the organization. In this thesis we search for the potential causes of the intra-organizational discrepancy by examining Sweden and Finland. These two states have approximately the same prerequisites for granting asylums, but vary greatly in number. In order to determine what causes this incongruity the states will be analyzed with two variables. The first variable examines the major political parties’ refugee policy, through framing theory. The second variable analyses the Migration Boards through Max Weber’s bureaucracy theory and scrutinizes the Director Generals of these organizations. Both variables result in sub-conclusions, which in the end are merged into one. The final conclusion determines that both variables are jointly contributing to the Swedish-Finnish discrepancy with the states having different political foundational frames, varying levels of bureaucracy of the Migration Boards and different approaches towards immigration from the Director Generals of the Migration Boards

Inszenierungen des Traumerlebens: Fiktionale Simulationen des Träumens in deutschsprachigen Erzähl- und Dramatexten (1890-1930)

Die vorliegende Arbeit widmet sich in gezielter Fokussierung dem Themenkomplex fiktionaler Traummimesis. In Analysen werden die Strategien von literarischen Darstellungen des Traumerlebens untersucht. Bei der Textauswahl werden ausschließlich eindeutig markierte Träume in deutschsprachiger Erzählliteratur und Dramatik berücksichtigt. Dabei stehen die Zeiträume im Zentrum, in denen sich innovative Zugänge in der literarischen Auseinandersetzung mit Träumen abzeichnen. Nach einem historischen Vorlauf von der Mitte des 18. Jahrhunderts bis zum Beginn des 19. Jahrhunderts liegt der Schwerpunkt auf dem Zeitraum von etwa 1890 bis 1930. Damit soll eine Lücke in der Forschungslandschaft zum Traum in der Literatur geschlossen werden

Investigations Of Heat Transfer And Components Efficiencies In Two-Phase Isobutane Injector

Renewable energy sources may be applied to drive refrigeration and air-conditioning systems, e.g. solar radiation, geothermal resources, heat derived from biomass or waste heat rejected form various thermal processes. In this case absorption refrigeration systems and ejection systems may be used for cooling applications. In both these systems the crucial problem is the development of a suitable liquid pump. Energy consumption to drive these systems is not a major problem here as in most cases amount of energy required to drive a mechanical pump is a contribution of at most a few percent of the overall energy balance of the system and in most cases is of the order of magnitude 1%. Therefore the most important problem is a special difficulty to select of a commercially available liquid pump for the thermal driven cycle (absorption or ejection one). Such pumps should be low cost, small size and should produce sufficiently high compression rate for the discussed applications. They should also be adapted to work in particularly hard operating conditions resulting from the application in the discussed systems low boiling fluids: these are high penetrating substances, most of them are chemically aggressive and high susceptible to erosion caused by cavitation destruction. Under present conditions most of the pumps that could be applied have inadequate overall dimensions as well as are very expensive so the contribution of the cost of the relevant pump is dominant in the total cost of the system. As an effect refrigeration systems driven by renewable thermal sources are commercially unprofitable and unattractive. Paper deals with experimental investigation of two-phase vapour-liquid injector as a liquid pump in refrigeration systems. The selected experiment results for the injector are presented for the case of isobutane as working fluid. Investigations covers the operation characteristics of the injector as well as heat transfer coefficient, as well as evaluation of the efficiencies of the elements of the injector. It was demonstrated that these efficiencies depend on operating parameters and may not be treated as contact quantities

Electromagnetic acoustic boiler tubes inspection with robotic device

This paper dedicated to electromagnetic acoustic (EMA) inspection of boiler tubes in the process of regular maintenance for prevention of tube rupture. This non-destructive testing method is developed to replace commonly used ultrasonic method of inspection which is costly and very labor intensive. During proposed EMA inspection surface of tubes does not require sandblasting and special coupling between measuring tool and tube wall. Commonly used ultrasonic method, based on detection of the wave generated by a piezoelectric effect of a crystal transducer, provides accurate but sparse data and takes long time to inspect healthy boiler condition. Electromagnetic acoustic transducer EMAT generates such wave directly in tube material by electromagnetic method. EMAT technology is well known and used in many nondestructive testing situations. This method relies on generating ultrasound wave directly in the metal in the form of elastic wave with ultrasonic velocity, characteristic for a given metal. There are two ways that EMATs can generate elastic energy directly in the boiler water-wall. The first is via the “Lorentz force” mechanism where interaction between an applied magnetic field and induced eddy currents produces an elastic wave. The second is through magnetostriction (MS), where an alternating magnetic field generates an alternating elastic force. Developed and fabricated with high energy Neodymium-Iron-Boron permanent magnets with magnetic energy over 56 MGsOe by M. Bergander [1] transducer is able to generate strong elastic wave using magnitostrictive properties of tube material for prediction of the tube thickness. In the special conditions of coal-fired boiler inside and outside surfaces of the tube are covered by erosive and corrosive layers. Those corrosive and erosive layers have good magnitostrictive properties which allow making water-wall thickness measurement without sand blasting and without necessity to have coupling between measurement tool and the tube material surface. This method allows inspecting boiler tubing much faster with the high quality of assessment. To make process of inspection faster claiming robot has been designed. This robot is able to deliver sensor of the measuring device to the surface of the tube and provide stable data reading. Using such robotic device it is possible to do automation of the inspection procedure

Integrative Therapie einer Patientin mit komplexen psychosomatischen Beschwerden

We present the case of a 76-year-old female patient with complex psychosomatic complaints. The patient suffered from depression, panic attacks, chronic pain and dyspepsia with nausea and loss of appetite. In addition to the conventional psychosomatic care, the patient received individual homeopathic treatment for her dyspepsia, resulting in complete remission. The therapeutic value of homeopathy in the present case is discussed in the context of recent findings from placebo research

Experimental Investigations of Low-temperature Driven Ejector for Isobutane

The paper describes experimental and numerical investigation of ejection refrigeration system dedicated for short time storage of food products for local retail market, especially in rural areas. This work was sponsored by US Dept. of Agriculture under Phase I SBIR program. This novel method does not use electricity and is cleaner for the environment than other refrigeration techniques. One of the crucial problems of the retail market of perishable foodstuff is a lack of efficient and appropriate refrigerated storage capacity. The existing technology in most cases uses conventional refrigeration systems that consume a large amount of electricity, they are expensive as well as use harmful working substances (usually artificial GHG gases that have high greenhouse warming potential in comparison with most of the natural substances). In addition, ensuring required storage conditions in terms of the stability of the product temperature and humidity may be a challenge for most of the existing short time storage refrigerators.  Responding to these challenges we developed an ejector based refrigeration system that 1) utilizes solar or waste heat (below 100C temperature) as a main source of energy, 2) eliminates the mechanical compressor, which is a main user of electricity and the main contributor to maintenance and reliability issues in cooling systems and 3) operates without any ozone depletion effects and any greenhouse gas (GHG) emissions, when used with natural refrigerants. Until recently, ejector use in refrigeration systems was considered as controversial because most of the research conducted in the past has yielded only theoretical results without visible, commercial products. The main issue was a relatively low value of coefficient of performance (COP) in comparison with classical compression systems. Selection of the working fluid for the refrigeration or air-conditioning system is the crucial problem because the system efficiency is strongly influenced by the thermodynamic properties of the refrigerant. We found that the maximum efficiency can be achieved with natural refrigerants, of which isobutane is by far the most favorable. However, primarily due to its flammable nature, isobutane is not currently allowed in commercial systems in USA and Canada although it has been used for many years in all domestic refrigerators in Germany and other EU countries where appropriate safety precautions and regulations were developed. For US market, we identified two other environmentally friendly equivalents to isobutane: R245fa and R1234ze both with zero ozone depletion potential. The research described here had overcome another limitation - a lack of appropriate methods for the design of ejector geometry. Such methodology was developed and tested in a variety of thermodynamic cycles for cooling, heating and heat pumps. The test stand and the experimental results of investigation for isobutane as a working fluid along with CFD modelling results are shown and discussed in the paper in details.

Remaining life assessment for boiler tubes affected by combined effect of wall thinning and overheating

Boilers, the most troublesome components of electric power, chemical and processing plants generate high costs in unscheduled shutdowns, repairs and power replacement. Every occurrence of ruptured tubes leads to emergency shutdown of the entire plant. This paper describes the joint international effort to develop faster and more efficient methods for condition assessment and remaining life prediction for boiler tubes made of low-carbon steel. Authors have undertaken a systematic research with the major objective to correlate the results of combined nondestructive testing (NDT) with condition assessment of boiler tubes. The evaluation included non-contact wall thickness measurement with EMAT technology plus internal oxide layer measurement with specialized ultrasonics. While the first method shows the remaining tube wall thickness, thus allowing calculating total stress, the latter one has the potential to characterize microstructure degradation, which up to now could only be determined by destructive analysis. The special attention was directed towards identification and analysis of creep damage due to overheating. In recent years, techniques were developed to identify heat damage by measuring the thickness of internal oxide scale because even a thin scale can seriously impede heat transfer causing elevation of temperature in tube wall. A combined effect of wall thinning and the “degree of overheating” on tube remaining life was investigated. The uniqueness of this work lies in one of the first attempts to develop and validate a tool for methodology for condition assessment and remaining life prediction, for Steel20 tube material, while most of previous authors had concentrated on Cr-Mo steels. Another contribution is the combined treatment of two different damage mechanisms and practical utilization of two various NDT techniques. To-date, both results are treated separately, and consequently separate reject criteria exist for overheating and separate for wall thinning. As a result of work presented in this paper, a procedure was recommended to calculate the tube remaining life based on the results of two ultrasonic tests

Hva bygger lønnsomhet? En gjennomgang av lønnsomhetsfaktorene i bygg- og anleggsbransjen

Studien retter oppmerksomhet mot en bransje med økt aktivitetsnivå, høy omsetning og avtagende marginer. Bygg- og anleggsbransjen opplever stor konkurranse om prosjektene, hvilket skaper lønnsomhetsvariasjoner mellom de store virksomhetene. Forskningsarbeidet som er gjort, baserer seg på analyse av faktorer for lønnsomhet i bygg- og anleggsbransjen. Disse faktorene har kommet frem gjennom en bedrifts- og bransjespesifikk og makroøkonomisk analyse. Analysen av de tre nivåene gir et helhetlig bilde av lønnsomheten og lønnsomhetsvariasjonen blant de store virksomhetene i bygg- og anleggsbransjen. Analysen anvender paneldata basert på årsregnskapene til 36 av de største virksomhetene i Norge, for perioden 2010-2020. Studien har brukt økonometrisk metode på random-effects modell, hvor Microsoft Excel og RStudio 2021.09.2 er benyttet til analyseformålet. Funnene i studien viser at de bedriftsspesifikke faktorene best forklarer lønnsomheten og lønnsomhetsvariasjonen i bransjen. Videre viser funnene at; (1) Virksomhetenes størrelse er avgjørende for lønnsomheten, i form av effektiv kapitalbruk. Derimot vil en økning i størrelse blant de største virksomhetene, påvirke lønnsomheten negativt. (2) Konkurranseintensiteten og prispresset har en negativ påvirkning på lønnsomheten. (3) Arbeidskapitalstyringen og likviditetsnivået er avgjørende for å være lønnsom i en konkurransepreget bransje. Variasjon i utvalgets lønnsomhet, kan forklares gjennom graden av operasjonell leverage. (4) Bygg- og anleggsbransjen er funnet å være sterkt påvirket av makroøkonomiske faktorer som politiske tiltak og økonomiske forhold