•Unique, directly measured, melting front propagation experimental data is presented.•Best results are obtained using large values of mushy zone constant (vary-ing between C = 109 and ...C = 5·109).•Effective thermal conductivity of solid NaNO3 higher than values in literature.•Comparison of temperature profiles can sometimes lead to false validation
Renewed interest in concentrated solar power has sparked increase in research concerning high temperature phase change materials. A large number of these studies are focused on numerical modeling and heat transfer optimization. However, most of these models are validated using either inadequate (low temperature) experimental data for low-temperature melting or temperature measurements acquired during melting in very specific geometries. The goal of this paper is to help fill the gap in the available experimental data for model validation by providing unique directly measured front propagation data for high temperature phase change materials.
The experimental setup for direct melting front propagation acquisition during the sodium nitrate melting is presented. Three experiments with different Rayleigh numbers and orientation are presented. The acquired data was used for numerical model validation. The model was based on the finite volume approach using the frequently used enthalpy-porosity method. It is shown that the best results are obtained using much larger values of the mushy zone constant than those found in literature. Furthermore, by comparing temperature profiles between the experiment and simulations it is shown that temperature measurements (which are one of the most used validation methods) can, in some cases, lead to a false validation.
Although the power system usually always appears stable and reliable to consumers, a lot of work and research goes into keeping the power system both stable and reliable under constantly changing ...conditions and in these increasingly demanding times. One of the key issues in the power system is maintaining stability after large disturbances in order to prevent the loss of synchronicity of the generators in the system. Today’s generator protection systems mostly use measurements of impedance change to detect generator out of step. This article discusses the possibility of detecting the loss of synchronicity by using real time load angle measurements. The authors propose a real time load angle measurement algorithm and present the results of the algorithm’s testing performed on a real hydrogenerator. The results show that the developed algorithm gives highly accurate real time load angle measurements with the maximum possible resolution and that the load angle can be used for detecting the synchronous generator out of step.
•Ancillary services provided by photovoltaic power plant.•Realistic P-Q capability chart at point of common coupling of photovoltaic power plant.•Theoretical equations for the contribution to the ...total output power are derived.•The comparison with real case measurements.
This paper presents the proposal of the methodology for the development of realistic P-Q capability chart at point of common coupling of photovoltaic power plant, comprised of multiple inverter units and connected to medium voltage grid. Theoretical equations for the contribution to the total active and reactive power of the plant are derived for all plant components: inverters, low voltage cables, transformers, medium voltage cables and auxiliary consumption. It is concluded that equations for total active and reactive power are dependable on only two changing variables: voltage and momentary generation power of inverters. Equations for maximum and minimum values for total active and reactive power are further derived when known maximum and minimum values of changing variables are entered to equations, and these are presented on graph diagram as curves. Area in P-Q diagram within such calculated border curves is area of possible power plant operation points at the point of common coupling. Such representation model of this type of plant has not been proposed before. The proposed methodology has been applied to the case study plant and its operation P-Q diagram is constructed Measurements conducted on this case study plant are compared with calculated values for necessary corrections to the model.
Hemoptysis is a life-threatening emergency and a possible first sign of pulmonary tuberculosis. Minor hemoptysis, as a possible clinical aspect of adult tuberculosis, usually has limited course and ...in most cases, is resolved with antitubercular therapy. However, massive hemoptysis is a life-threatening condition associated with a mortality rate of >50% in the absence of well-timed and proper handling. Hence, prompt diagnosis and early interventions are essential. In this study, we present a rare case of pseudoaneurysm causing massive hemoptysis in a patient with pulmonary tuberculosis.
This work shows genetic algorithm approach to the optimum wire busbar design. Parameters of the wire busbar are mapped into a chromosome like a string. This includes insulator string type, wire ...conductor type and number, bundle wire conductor distance, rigid spacer number, phase distance, wire conductor nominal stress, 3D truss L elements types and foundation type. GA uses natural selection on a population of such strings. The fitness function is the wire busbar price. GA performance is presented on one example with variation of input data--nominal current, short-circuit current and short-circuit duration.
Actual trends of increased utilization of renewable sources in residential sector impose new requirements for domestic energy system operation. Recent research results have shown that a high level of ...energy autonomy could be achieved by the utilization of such systems in a residential building located within the European continental climate zone. That is particularly interesting in the light of the fact that in near future access to the hourly electricity market will be enabled to all households thus acting as prosumers. In this paper, the energy system comprising of a photovoltaic thermal collector, heat storage, heat pump and auxiliary energy sources, sized to cover the most of electricity, heating and cooling demand of a selected low-energy family house (180 m2 heated and cooled area, 75 m2 useful roof area, located in northwest Croatia) was considered. By analysis of yearly operational profiles, required exchange of energy on electricity market was estimated. Detailed mathematical model of the system was used for hourly simulation in order to evaluate impact of operational strategies on both renewable energy sources utilization and profitability. Two different control strategies were compared in typical days defined by profiles of energy demands, solar irradiance and electricity price. The simulation results showed how the change in operation strategy can reduce operational cost.
Lung cancer is the leading cause of cancer death in Europe. Screening by means of low-dose computed tomography (LDCT) can shift detection to an earlier stage and reduce lung cancer mortality in ...high-risk individuals. However, to date, Poland, Croatia, Italy, and Romania are the only European countries to commit to large-scale implementation of targeted LDCT screening. Using a health systems approach, this article evaluates key factors needed to enable the successful implementation of screening programs across Europe. Recent literature on LDCT screening was reviewed for 10 countries (Belgium, Croatia, France, Germany, Italy, the Netherlands, Poland, Spain, Sweden, and United Kingdom) and complemented by 17 semistructured interviews with local experts. Research findings were mapped against a health systems framework adapted for lung cancer screening. The European policy landscape is highly variable, but potential barriers to implementation are similar across countries and consistent with those reported for other cancer screening programs. While consistent quality and safety of screening must be ensured across all screening centers, system factors are also important. These include appropriate data infrastructure, targeted recruitment methods that ensure equity in participation, sufficient capacity and workforce training, full integration of screening with multidisciplinary care pathways, and smoking cessation programs. Stigma and underlying perceptions of lung cancer as a self-inflicted condition are also important considerations. Building on decades of implementation research, governments now have a unique opportunity to establish effective, efficient, and equitable lung cancer screening programs adapted to their health systems, curbing the impact of lung cancer on their populations.
Primary sarcoma of the lung is a very rare malignant tumor accounting for less than 0.5% of all lung tumors and presenting diagnostic and treatment challenge. We describe a case of a patient ...diagnosed with primary lung undifferentiated pleomorphic sarcoma developing subsequent peritoneal and small bowel metastases, which stand for highly unusual disease presentation.
A 57-year-old male presented with extensive partially necrotic tumor in the left upper lobe (LUL) of the lung that involved LUL bronchus and extended to the visceral pleura. There was no evidence of nodal or visceral dissemination. After initial presentation, the patient was admitted to the hospital's pulmonology department for further workup. The most likely diagnosis based on biopsy specimen was poorly differentiated sarcoma. Left pneumonectomy with mediastinal lymph node dissection was performed. The final pathohistological diagnosis (PHD) was undifferentiated pleomorphic sarcoma (UPS). Three months after lung surgery, a follow-up CT scan was done which showed a 60-mm obstructive metastatic intraabdominal lesion with small bowel infiltration and further separate peritoneal deposits. Unfortunately, an urgent surgery had to be performed as the patient developed signs of acute abdomen due to bowel perforation. Only 2 months later, the patient passed away at home.
Treatment options of UPS are based on algorithms used in treatment of extremity lesions with well-established role of surgery. However, the role of perioperative chemotherapy remains equivocal with no strong evidence-based data due to the rarity of the disease. Small bowel is an unexpected metastatic site, but of significant clinical relevance.
Summary
Background
This study evaluated the prevalence of spreading pathways in nontuberculous mycobacteria (NTM) pulmonary infections according to nodular distribution patterns seen on chest ...computed tomography (CT).
Methods
This study included 63 patients diagnosed with NTM lung infections who underwent CT at our institution. A retrospective analysis of CT images focused on the presence and distribution of nodules, presence of intrathoracic lymphadenopathy and the predominant side of infection in the lungs. The findings were classified into five groups; centrilobular (bronchogenic spread), perilymphatic (lymphangitic spread), random (hematogenous spread), combined pattern and no nodules present. The groups were then compared according to other CT findings.
Results
Among 51 (81%) patients identified with a nodular pattern on chest CT, 25 (39.8%) presented with centrilobular, 7 (11.1%) with perilymphatic, 6 (9.5%) with random and 13 (20.6%) with combined nodular patterns but located in different areas of the lungs. The right side of the lungs was predominant in 38 cases (60.3%). Intrathoracic lymphadenopathy was evident in 20 patients (31.7%). Significant differences in distributions of nodular patterns were seen in patients infected with
Mycoplasma avium complex
(MAC) associated with centrilobular pattern (
p
= 0.0019) and
M. fortuitum
associated with random pattern (
p
= 0.0004). Some of the findings were related to perilymphatic nodules between other isolated species of NTM (
p
= 0.0379).
Conclusion
The results of this study showed a high proportion of perilymphatic nodules and right-sided predominance in the upper lobe, which, combined with intrathoracic lymphadenopathy is highly suggestive of the lymphangitic spread of lung NTM infections.
The paper deals with a new way of determining a fault location in an electric power distribution radial feeder using an artificial neural network (ANN) and presents a new centralized protection ...method based on ANN. The aim of the devised algorithm is to detect the presence of a fault in a radial feeder and to disconnect faulted laterals from the distribution network. The protection schemes that are currently in use cannot leave the whole feeder energized by disconnecting faulted laterals only without even short de-energization of the healthy part of the feeder. A simulation model is also made for training the ANN and for testing the results. Current values for faulty and healthy states are generated by the simulation model and are used as training and testing data for the algorithm. The purpose of the algorithm is to make a decision which feeder circuit breakers should trip. The simulation model and the ANN are modeled by using MATLAB tools. The results show that the tripping of circuit breakers initiated by the algorithm is correct for all states.
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