High Radiation Density Research Articles

Numerical Analysis of Non-Sphericity of Particles of Powder Material and their Effect on Packing Structure for Concentrated Solar Power Applications

Concentrated solar power technology represents a novel approach to generating solar power, characterized by high solar radiation density and uninterrupted operation. To store thermal energy and extend system operating hours, concentrated solar power systems rely on thermal energy storage. Selecting the appropriate heat storage media is crucial for designing a cost-efficient and straightforward system capable of withstanding high processing conditions. Among many powder materials, bauxite powder stands out as alternatives to conventional molten salt for thermal storage media due to its widespread availability and suitability for operating conditions. Particle shape, particularly its sphericity, plays a vital role in efficiently packing particles which directly affects to heat transfer properties. To investigate this effect, three samples of particles with different shape were formed: spheres, ellipses, and cylinders using Discrete Element Method with equal volume and material properties, and only variation of their sphericity factors. The study focused on the analysis of the porosity of the packed bed of particles with different shapes and its influence on the packing structure properties. The analysis of local packing fraction revealed that elliptical and cylindrical particles samples exhibited reduced heap formation and a more uniform distribution along z direction during vertical packing. The coordination number and radial distribution function analyses for these non-spherical particles showed a greater number of contacts between particles and disordered distribution of particles due to mechanical interlocking of non-spherical particles. The results indicated that the deviation of sphericity has a positive impact on the denser packing of particles generated more contacts and higher local packing fraction.

Greenhouse gas emissions reduction and energy savings for a dredger at port area using hybrid photovoltaic power system onboard

For reducing greenhouse gas (GHG) emission and saving energy, a hybrid photovoltaic (PV) energy system comprised of grid-connect and off-grid modes was utilized on a dredger at emission control area (ECA) such as a port area. The experiments on this hybrid PV power system were carried out to evaluate the electric energy consumption of each equipment onboard in three operation modes (dredging, rest and idle) of dredger and to analyze the contribution of such a PV power system. The PV array had charging batteries in grid-connect mode and converted the PV power to alternating current (AC) directly during daytime period. At nighttime, the batteries could supply the electric power in off-grid mode. Even this dredger is no large free deck area for installing PV arrays onboard, the power conversion for PV array can offer about 1.0 % of total demand electric energy yearly. After evaluating the electric power consumption of each equipment onboard at different dredger operation mode, the proposed hybrid PV power system can offer 4.0 % (3.9 kWh by 96.8 kWh) of energy demand in grid-connect at rest mode and supply 100 % (29.85 kWh by 29.85 kWh) energy for dredger equipment in off-grid without diesel generator running at idle mode. This hybrid PV power system on the dredger has not only saved marine diesel oil (MDO) 2094.2 kg/year, reduced GHG of CO2 about 6455 kg/year, SOx about 3.942 kg/year and particulate matter (PM) around 1.97 kg/year but also reduced the diesel generator maintenance cost from stop running for 15 h/day and saved the cost of fuel (MDO) about USD 2128.5/year. The hybrid PV power system exhibited very effective efficiency of PV array and optimized the installation of batteries bank in ship with limited deck space at ECA and port area with high solar radiation density zone.

New Inogranic Scintillators’ Application in the Electromagnetic Calorimetry in High-Energy Physics

Scintillation crystals Gd3Al2Ga3O12 (GAGG) are an excellent candidate for application in ionizing-radiation detectors because of their high radiation resistance, density and light yield. These crystals can be used in combination with lead tungstate (PbWO4 or PWO) crystals for the development of a new generation of electromagnetic calorimeter with advanced spatial and energy resolutions in a broad energy range. PWO crystals enable the accurate detection of high-energy photons, while GAGG crystals provide the possibility of precisely measuring photon energies, down to a few MeV. Different options for a composite electromagnetic calorimeter based on PWO and GAGG crystals are considered to optimize spatial and energy resolutions in a broad energy range (from 1 MeV to 100 GeV). In particular, different lengths of the GAGG section of the calorimeter are considered, from 0.5 to 10 cm. The separation of signals from photons and hadrons is also taken into consideration through the study of shower shape in the calorimeter. The optimization is based on Geant4 simulations, considering light collection as well as the use of different photodetectors and electronic noise. Simulations are verified with light yield measurements of GAGG samples obtained using radioactive sources and test beam measurements of the prototype of the PWO-based Photon Spectrometer of the ALICE experiment at CERN.

LOCL-08 SAFETY AND FEASIBILITY OF RHENIUM-186 NANOLIPOSOME (186RNL) IN RECURRENT GLIOMA: THE RESPECT™ PHASE 1 TRIAL

Abstract BACKGROUND Liposomal rhenium-186 (186RNL) is a potent source of electrons with short path length, low dose rate, high radiation density and gamma emission. Preclinically, 186RNL via convection enhanced delivery (CED) achieves very high doses of targeted radiation and a wide therapeutic index. We report the updated results of ReSPECT, the first in man, dose escalation phase 1 trial of 186RNL in recurrent glioma. METHODS Following computer assisted treatment planning and placement of intracranial catheter(s), we performed a single administration of 186RNL by CED. Whole body planar and SPECT/CT imaging was obtained on days 1-8 following treatment for dosimetry and distribution. Patients were followed for safety, progression and survival. RESULTS Twenty-one patients across 7 cohorts received 1.0-22.3mCi in a tumor volume of 0.6-8.80mL. Mean tumor volume was 8.3mL (0.9-22.8mL). Patients had a mean of 1.7 recurrences, 5 with prior bevacizumab. 19 (91%) were grade 4 gliomas, and 100% were after cohort 4. We used a CED rate of 5-20µl/min per catheter, with 1-4 catheters per patient. Tumor mean absorbed radiation dose was 255Gy (8.9-740Gy) while exposure outside the brain was negligible. The mean percentage tumor in the treated volume (Tu/Tv) was 60.3% (19.8%-100%). Thus far, we have observed no dose limiting toxicities, one grade 3 treatment related adverse event (AEs), and the majority of AEs were mild in intensity. The incidence and severity of AEs did not correlate with increasing dose. Mean Tu/Tv in patients not receiving prior bevacizumab was 75% vs. 48% in those that had. Thus far, overall survival (OS) in 16 bevacizumab naïve patient is 49 weeks with 7 patients still alive and a positive correlation of OS to Tu/Tv. CONCLUSIONS 186RNL achieves high absorbed doses without significant toxicity with favorable overall survival. Updated delivery feasibility, safety and overall survival will be presented.

LOCL-04 SAFETY AND FEASIBILITY OF RHENIUM-186 NANOLIPOSOME (186RNL) IN LEPTOMENINGEAL METASTASES [LM] PHASE 1/2A DOSE ESCALATION TRIAL

BACKGROUNDLM is a devastating subarachnoid (SA) complication most commonly from breast, lung, melanoma, and gastrointestinal malignancies affecting 110,000 in the USA. Common therapies are radiation and SA/IV chemotherapy. Without treatment, survival is short with limited treatment options and better options urgently needed. 186RNL emits beta particles (with gamma-rays) with low dose rate and high radiation density. We report first results of the enrolling ReSPECT-LM phase 1/2a 186RNL-LM dose escalation trial. MATERIAL AND METHODSPreclinical syngeneic rat model animals were 186RNLtreated at day15 with intraventricular186RNL(0.689 mCi) providing mean CSF-radiation absorbed dose=1,136 ±226Gy. 50% control animals[unloaded liposomes] and 100%186RNL treated animals were alive at 14days. At 4 weeks, 75% control animals and 37.5% treated animals had died. Based on this preclinical data and 186RNL recurrent glioma human experience, a phase I/2a dose escalation ReSPECT-LM Trial was initiated to characterize safety/tolerability of a single intrathecal(IT) 186RNL administration. Following, to identify maximum tolerated/feasible doses, 186RNL anti-tumor activity as a single agent in LM patients (breast and NSCLC), characterize 186RNL pK & dosimetry via Ommaya delivery, determine the overall response rate (ORR) for 186RNL treated patients based on CSF/radiographic findings, and describe survival distribution. RESULTSReSPECT-LM is enrolling and 1st patient dosed (6.6 mCi186RNL, 5ml) via Ommaya reservoir. The dose was well-tolerated with no complaints/AEs as of Day 28 following treatment. Imaging and CSF tumor cell assays at pre &post-dose were performed. 186RNL gamma imaging confirmed rapid, complete and durable SA dose distribution through168hours. Pre-dose CSF tumor cell count was 70.77 cells/ml and following treatment, 39.79 cells/ml at 24, and ~6 cells/ml at both 48 &168hours. CONCLUSION186RNL’s unique formulation and characteristics may have promise for LM patients. An update of the ReSPECT-LM clinical trial will be provided.

CTNI-29. SAFETY AND FEASIBILITY OF RHENIUM-186 NANOLIPOSOME (186RNL) IN RECURRENT GLIOMA: THE RESPECT™ PHASE 1 TRIAL

Abstract BACKGROUND Liposomal rhenium-186 (186RNL) is a potent source of beta particles with short path length, variable dose rate, high radiation density and gamma emission. Preclinically, 186RNL delivered via convection enhanced delivery (CED) achieves very high doses of targeted radiation with a wide therapeutic index. We report the results of ReSPECT, the first in man, dose escalation phase 1 trial of 186RNL in recurrent glioma. METHODS Following computer assisted treatment planning and placement of intracranial catheter(s), we performed a single administration of 186RNL by CED. We obtained whole body planar and SPECT/CT imaging on days 1-8 following treatment for dosimetry and distribution and followed patients for safety, progression and survival. RESULTS Twenty-one patients across 7 cohorts received 1.0-22.3mCi in a volume of 0.6-8.80mL. Mean tumor volume was 8.3mL (0.9-22.8mL). Patients had a mean of 1.7 recurrences, 5 received prior bevacizumab. Overall, 19/21 patients and all after cohort 4 had grade 4 glioma (glioblastoma). We used a CED rate of 5-20µl/min per catheter, with 1-4 catheters used per patient. Mean absorbed radiation dose to the tumor was 255Gy (8.9-740Gy) while exposure outside the brain was negligible. The mean percentage tumor in the treated volume (Tu/Tv) was 60.3% (19.8%-100%). Thus far, we have observed no dose limiting toxicities, one grade 3 treatment related adverse event (AEs), and the majority of AEs were mild in intensity. The incidence and severity of AEs did not correlate with increasing dose. Mean Tu/Tv in patients not receiving prior bevacizumab was 75% vs. 48% in those that had. Thus far, overall survival (OS) in 16 bevacizumab naïve patients is 49 weeks with 7 (44%) patients still alive and a positive correlation of OS to Tu/Tv. CONCLUSIONS 186RNL achieves high absorbed doses without significant toxicity with favorable overall survival.

Simulation of urban microclimate with uhiSolver: software validation using simplified material data

BackgroundIncreasing urbanization as well as global warming requires an investigation of the influence of different construction methods and ground surfaces on the urban heat island effect (UHI effect). The extent of the influence of the urban structure, the building materials used and their surfaces on the UHI effect can be significantly reduced already in the planning phase using a designated OpenFOAM-based solver “uhiSolver”.ResultsIn the first part of this research work, it is shown that inner building details and components can be neglected while still obtaining sufficiently accurate results. For this purpose, the building model was divided into two layers: a surface layer without mass, where the interaction with radiation takes place, and a component layer, which contains all relevant components and cavities of the building represented with mass-averaged material properties. It has become apparent that the three parameters—albedo, heat capacity and thermal resistance—which have a decisive influence on the interaction, have different effects on the component temperatures and the surface temperatures. In the second part of this research work, dynamic 3D computational fluid dynamics (CFD) simulations are performed with uhiSolver for a residential block in Vienna. Comparing the simulation results with measurement data collected on site, it is shown that the simplified assumption of homogeneous material data for building bodies provides very good results for the validation case investigated. However, the influence of the greening measures in the courtyard of the residential block on the air temperature is found to be negligible. Furthermore, it was observed that due to locally higher radiation density, lower air velocities and higher air humidity, the apparent temperature in the courtyard is sometimes perceived to be higher than in the adjacent streets, despite the lower air temperature.ConclusionsSimplifying the modeling process of the uhiSolver software by reducing the model complexity helps to reduce manual work for setting up appropriate boundary conditions of buildings. Compared to market competitors, good results are obtained for the validation case Kandlgasse presented in this research work, despite the simplifications proposed. Thus, uhiSolver can be used as a robust analytical tool for urban planning.

Up-Conversion Luminescence Processes in NaLaF4 Doped with Tm3+ and Yb3+ and Dependence on Tm3+ Concentration and Temperature.

In this work, luminescence processes in polycrystalline NaLaF4:Tm3+ and NaLaF4:Tm3+,Yb3+ materials were studied. Luminescence spectra and decay kinetics measurements were performed for NaLaF4 doped with various Tm3+ concentrations (0.01, 0.1, 0.5, 1, and 2 mol%) under direct excitation to 3P0, 1D2, 1G4, and 3H4 states. It was found that some of the Tm3+ excited states are more affected by Tm3+ concentration than other states. Under infrared excitation of Yb3+, energy transfer to Tm3+ occurred and intensive ultraviolet and blue up-conversion luminescence was observed. Possible up-conversion mechanisms are discussed. Spectroscopic measurements show that long-duration excitation radiation reduces ultraviolet up-conversion luminescence intensity, and this intensity reduction is related to sample heating due to high excitation radiation density and a poor heat sink from samples. It was found that sample configuration for spectroscopic measurements is crucial to correctly describe measured up-conversion luminescence spectra.

Peculiarities of the chemical composition of fungal bodies of the paranasal sinuses

Introduction: The significance of fungal microflora in the development of chronic rhinosinusitis tends to increase. The purpose of the study: We had studied the chemical composition of fungal bodies of odontogenic and nonodontogenic origin to determine the relationship between fungal sinusitis and previous endodontic treatment. Methods and materials: The 7 samples of the most common dental endodontic materials and 32 fungal ball removed from the paranasal sinuses in patients were examined by electron microscopy and masspectrometry: 22 of them were from the maxillary sinus in persons with a probable odontogenic cause of the disease (group 1), and 10 with the exception of odontogenic factor – 5 from the maxillary sinus - group 2 and 5 - from the sphenoid - group 3). The resultsand disscusion: In areas with high radiation density of fungal balls, its level in group 1 was 1173.6 ± 257.9 HU, groups 2 and 3 - 283.2 ± 21.8 HU and 262.6 ± 3 HU, and the radiation density from the samples with base it’s level in all groups did not differ among them and was from 50.1 to 55.0 HU. It was found that in all samples dental materials there was a content of Zn with a mass fraction from 0.71 ± 0.42% to 85.51 ± 0.05%. When analyzing the structure of fragments of fungal balls from areas with a base level of radiation density in patients of all three groups, its homogeneity and absence of crystalline inclusions were noted. In contrast, in fragments of fungal ball from areas of high radiation density there where a significant number of crystals in individuals with established odontogenic factor (group 1) and their absence in the material of groups 2 and 3. In the composition of samples of fungal balls from areas with high radiation density, it was found that in group №1 in 10 samples (45.45%) showed a significant content of Zinc (average mass fraction - 23.71 ± 4.45%), and Calcium was found in 40.9% of the samples at the level of 3.8 ± 1.33%. The chemical composition of areas of fungal bodies with high radiation density in individuals with excluded odontogenic factor (group 2 and group 3) was similar and was characterized by the presence of high level of Calcium from areas with increased radiation density of 24.38 ± 6.22%, and 22.04 ± 5,72%, while the background (group 2 - 1.26 ± 0.33%, group 3 –0.90 ± 0.34%). Zinc and other chemical elements - markers of dental materials in groups 2 and 3 were not detected. Conclusions: All dental materials we examined contain Zn and chemical elements are not characteristic of tissues of biological origin (Ba, Zr, W, Co and Ti), the content of which may cause increased radiological density of the tissue of the fungal ball. Elevated Zn and Ca content was detected in 45.45% and 40.9% of samples of fungal ball of odontogenic origin, and in almost all samples of fungal ball of neodontogenic origin, regardless of the location of the sinus (maxillary or sphenoidal), Ca was detected, which allows to predict the absorption of these chemicals. elements from the tissues surrounding the fungal body, as the main mechanism of their accumulation in concentrations that cause the formation of areas of high radiation density.

Microstructure Refinement Effect on EUROFER 97 Steel for Nuclear Fusion Application

In Europe EUROFER 97 has been recognised as reference steel for the nuclear costructions under high radiation density for first wall of a fast breeder reactors as well as in other high stressed primary structures such as the divertors, blanklet and vessels. Following to this a EUROFER 97 detailed knowledge of the microstructure evolution after thermo-mechanical processing is required, because the material mechanical properties are interesting also for innovative solar plants, i.e. NEXTOWER project. A detailed knowledge of process optimisation is mandatory because EUROFER 97 steel mechanical properties and microstruture are heavily influenced and improved (and easily affeted) by thermomechanical treatments. In this paper the effect of thermo-mechanical parameters on the grain refinement of EUROFER 97 has been investigated by cold rolling and heat treatment on pilot scale.

Features of diagnostics of fungal ball of paranasal sinuses of iatrogenic genesis

Introduction: There are various theories of the origin of areas with high radiation density in the fungal ball of the paranasal sinuses: X-ray contrast dentist filling material; accumulation of zinc due to enzymes of the metalloproteinase group; formation of osteophytes, etc. The purpose of the study: to study the chemical composition of areas of fungal balls that have high radiological density. Methods and materials: The results of research of 26 samples of fungal bodies by scanning electron microscopy and spectrometry removed from maxillary sinuses in patients with fungal sinusitis (4 – nonodontogenic, 22 – odontogenic origin) are presented. In addition, 5 types of material most commonly used for endodontic treatment were studied. The results: It was found that fungal bodies of odontogenic origin have a heterogeneous structure with the presence of crystalline inclusions, the elemental composition of which has the characteristics of materials for endodontic treatment (Ba, Zr, W, Co), or increased content in the fungal ball of trace elements (Ti, Al and Zn), in quantities that are not characteristic of organic compounds. Conclusions: Scanning electron microscopy in combination with spectrometry can be used to identify foreign bodies of the maxillary sinus of exogenous (iatrogenic) origin and determine their role in the development of the fungal ball.

Study of the radiation resistance of Ni nanotubes to irradiation with Xe22+ ions with an energy equal to fission fragments

The paper presents data on the radiation resistance of Ni nanotubes when irradiated with heavy Xe22+ ions with an energy of 230 MeV and fluences of 5 × 1010–5 × 1012 ion/cm2. The choice of fluences of 5 × 1010–5 × 1012 ion/cm2 is due to the possibility of simulating the effects of single ion collisions at low irradiation fluences, for which the probability of two ions entering one point is quite low, and by modeling the effects of overlapping defects from two or more ions at high radiation densities. The initial nanostructures are polycrystalline nanotubes with a face-centered nickel phase. According to the results of X-ray phase analysis, no oxide impurities or oxide phases are observed in the structure of nanotubes, which indicates the absence of oxidative processes in the synthesized nanostructures. Also, for the irradiated samples, there are no new diffraction peaks, which indicates the absence of phase transition processes as a result of irradiation. It was found that, at low irradiation fluences, a change in the orientation of crystallites occurs, which indicates a rearrangement of the crystal structure and partial ordering. However, an increase in the irradiation fluence above 1 × 1011 ion/cm2 leads to a sharp decrease in long-range intensities, as well as a shift of diffraction maxima to the region of small angles, which indicates a distortion of the crystal structure and its partial disordering as a result of irradiation. In the case of large irradiation fluences, which are characterized by the occurrence of areas of overlapping ion trajectories, the material exhibits disorientation of crystallites in the structure, as well as the absence of pronounced texture orientations.

КОМПЛЕКСНЕ МОДЕЛЮВАННЯ ІНФРАЧЕРВОНОГО ЖАРЕННЯ М’ЯСНИХ ПОРЦІЙНИХ НАПІВФАБРИКАТІВ

In this paper the system-dynamic technology using the Vensim software package, which implements simulation of the infrared frying process of meat semi-finished products, was investigated. The limitation of the intensification of infrared frying is due to the fact that, at a high radiation density, surface overheating and a deterioration in the quality of finished products appear. To solve this problem, a set of theoretical and experimental studies was carried out, the purpose of which is the analytical and physical basis of simulation, which will allow for high-quality and economical heat treatment with a uniform radiation flux density on the product surface and minimize heat loss. By analytical modeling, a differential equation of the kinetics of temperature is obtained, which at a known average temperature of readiness of the inner layers of the product indicates the necessary time for frying the steaks, whose normal section is close to a half-ellipse. Physical modeling using an apparatus with a radiation flux reflector proves the adequacy of analytical modeling. Simulation is based on analytical modeling, which describes the relationships of system variables, and physical modeling, which sets the values and limitations of system variables. The effect of the presence of a radiation flux reflector in the apparatus on the duration of infrared frying and the organoleptic characteristics of the obtained product was studied. The nature and values of the temperature of the inner layers of the product, as well as the frying time obtained by simulation, correspond to analytical modeling and real frying. Experimenting with simulation models of processes and apparatus for infrared frying provides a systematic basis for their intensification and optimization. Key words: modeling, infrared frying, semi-finished meat product, radiation flux reflector, system analysis.

Austenitization and Tempering Temperatures Effects on EUROFER 97 Steel

EUROFER 97 is considered as standard steel for the nuclear applications in the case of high radiation density for first wall of a fast breeder reactors. Based on such consideration the microstructural behaviour of EUROFER 97 after thermo-mechanical processing is fundamental, since such materials properties are interesting also for innovative solar plants. In this paper the effect of thermo-mechanical behavior on the mechanical properties of EUROFER 97 has been analyzed by hot rolling followed by heat treatment on laboratory scale.A strong effect of reheating conditions before rolling on the material strength, due to an increase of hardenability following the austenite grain growth is found. A limited effect of the hot reduction and of the following tempering behavior is found in the considered deformation-range investigated. A loss of impact toughness is detected together with the hardness improvement.Mechanical properties are depending on the tempering temperature and an improvement of tensile yield stress (YS) and ultimate stress (UTS) was determined in tensile test carried on at T=550°C and T=650°C, e.g.: YS increase from about 400 MPa for standard EUROFER 97 [1] to about 550 MPa in samples treated by a tempering temperature of 720°C instead of the standard 760°C for EUROFER 97. Same trend has been found for UTS results.

Effect of thermo-mechanical parameters on the mechanical properties of Eurofer97 steel for nuclear applications

AbstractEurofer97 steel has been recognised in Europe as the reference steel for nuclear application under high radiation density. Following to this a detailed knowledge of microstructure evolution is required for such steel after thermo-mechanical processing. In this paper the effect of thermo-mechanical parameters on the mechanical behavior of Eurofer97 was investigated by hot rolling and heat treatment on pilot scale. Results show a strong effect was found of reheating temperature before rolling on the material hardness, due to an increase of hardenability following the austenite grain growth. A minor effect was found of the hot reduction and the tempering temperature in the total investigated deformation range. A loss of impact energy was found coupled with the hardness increase.

Expected neutrino fluence from short Gamma-Ray Burst 170817A and off-axis angle constraints

We compute the expected neutrino fluence from SGRB 170817A, associated with the gravitational wave event GW 170817, directly based on Fermi observations in two scenarios: structured jet and off-axis (observed) top-hat jet. While the expected neutrino fluence for the structured jet case is very small, large off-axis angles imply high radiation densities in the jet, which can enhance the neutrino production efficiency. In the most optimistic allowed scenario, the neutrino fluence can reach only $10^{-4}$ of the sensitivity of the neutrino telescopes. We furthermore demonstrate that the fact that gamma-rays can escape limits the baryonic loading (energy in protons versus photons) and the off-axis angle for the internal shock scenario. In particular, for a baryonic loading of ten, the off-axis angle is more strongly constrained by the baryonic loading than by the time delay between the gravitational wave event and the onset of the gamma-ray emission.

GRB 980425 host: [C II], [O I], and CO lines reveal recent enhancement of star formation due to atomic gas inflow

We have recently suggested that gas accretion can be studied using host galaxies of gamma-ray bursts (GRBs). We obtained the first ever far-infrared (FIR) line observations of a GRB host, namely Herschel/PACS resolved [CII] 158 um and [OI] 63 um spectroscopy, as well as APEX CO(2-1) and ALMA CO(1-0) observations of the GRB 980425 host. It has elevated [CII]/FIR and [OI]/FIR ratios and higher values of star formation rate (SFR) derived from line ([CII], [OI], Ha) than from continuum (UV, IR, radio) indicators. [CII] emission exhibits a normal morphology, peaking at the galaxy center, whereas [OI] is concentrated close to the GRB position and the nearby Wolf-Rayet region. The high [OI] flux indicates high radiation field and gas density. The [CII]/CO luminosity ratio of the GRB 980425 host is close to the highest values found for local star-forming galaxies. Its CO-derived molecular gas mass is low given its SFR and metallicity, but the [CII]-derived molecular gas mass is close to the expected value. The [OI] and HI concentrations, and the high radiation field and density are consistent with the hypothesis of a very recent (at most a few tens of Myr ago) inflow of atomic gas triggering star formation. Dust has not had time to build up (explaining high line-to-continuum ratios). Such a recent enhancement of star-formation would indeed manifest itself in high SFR_line/SFR_continuum ratios, because the line indicators are sensitive only to recent (<10 Myr) activity, whereas the continuum indicators measure the SFR averaged over much longer periods (~100 Myr). Other GRB hosts exhibit a mean SFR_line/SFR_continuum of 1.74+-0.32. This is consistent with a very recent enhancement of star formation being common among GRB hosts, so galaxies which have recently experienced inflow of gas may preferentially host stars exploding as GRBs. Hence GRB hosts may be used to investigate recent gas accretion.

3D-FEM electrical–thermal–mechanical analysis and experiment of Si-based MEMS infrared emitters

Designs, simulations, and fabrications of silicon-based MEMS infrared (IR) emitters for gas sensing application are presented. A 3D finite element method (3D-FEM) was used to analyze the coupled electrical–thermal–mechanical properties of a bridge hotplate structure (BHS) IR emitter and closed hotplate structure (CHS) IR emitter using Joule heating and thermal expansion models of COMSOL™. The IR absorptions of n- and p-silicon were calculated for the design of self-heating structure. The BHS and CHS IR emitters were fabricated synchronously using micro-electromechanical systems technology for a direct performance comparison. Both types of IR emitters were characterized by electrical and optical measurements. The experimental results show that BHS IR emitters have higher radiation density, lower power consumption, and faster frequency-response than CHS IR emitters due to the use of a thermal isolation structure and self-heating structure. Meanwhile, the simulated results agree well with the corresponding measured results, which indicate that the 3D-FEM-model is effective and can be used in the optimal design of electro-thermal devices.

Experimental system for long term aging of highly irradiated tube type receivers

Tube type receivers are being designed with codes that underestimate the thermo-mechanical fatigue and do not consider the effect of ultraviolet radiation. The effect of those phenomena in the receiver durability must be estimated from long-term aging tests, which are best carried out in a solar concentration facility. For this purpose, a solar dish, which was initially coupled to a Stirling engine, has been transformed into a test laboratory capable of reproducing the severe solar radiation concentration and temperature conditions typical of solar central tower receivers. In this facility, the temperature and the solar radiation density are controlled as independent variables. On one hand, the solar radiation density can be adapted to the test required level moving the sample along the dish optical axis. On the other hand, the temperature is controlled by an air flow, which is used as the heat transfer fluid. A test bed, including all the required elements for controlling the temperature and the solar radiation density, has been built up to satisfy certain solar irradiance and temperature ranges. So far, the solar dish has shown to be a very versatile facility for testing materials aging under high solar radiation densities.

Transport analysis of high radiation and high density plasmas in the ASDEX Upgrade tokamak

Future fusion reactors, foreseen in the “European road map” such as DEMO, will operate under more demanding conditions compared to present devices. They will require high divertor and core radiation by impurity seeding to reduce heat loads on divertor target plates. In addition, DEMO will have to work at high core densities to reach adequate fusion performance. The performance of fusion reactors depends on three essential parameters: temperature, density and energy confinement time. The latter characterizes the loss rate due to both radiation and transport processes. The DEMO foreseen scenarios described above were not investigated so far, but are now addressed at the ASDEX Upgrade tokamak. In this work we present the transport analysis of such scenarios. Plasma with high radiation by impurity seeding: transport analysis taking into account the radiation distribution shows no change in transport during impurity seeding. The observed confinement improvement is an effect of higher pedestal temperatures which extend to the core via stiffness. A non coronal radiation model was developed and compared to the bolometric measurements in order to provide a reliable radiation profile for transport calculations. High density plasmas with pellets: the analysis of kinetic profiles reveals a transient phase at the start of the pellet fuelling due to a slower density build up compared to the temperature decrease. The low particle diffusion can explain the confinement behaviour.