Radiation Load Research Articles

The influence of gyroscopic effects on dynamic responses of floating offshore wind turbines in idling and operational conditions

The present paper investigates the significance of gyroscopic effects on responses of floating offshore wind turbines (FOWTs). A 17-degree-of-freedom (DOF) FOWT model is rigorously developed using the Euler-Lagrange approach. Based on rational approximation of the radiation loads, an extended state-space formulation is then established for the coupled mechanical-hydrodynamic-controller system, enabling very efficient time-domain simulations. Different strategies for deriving linear system equations of motion (EOMs) within the Euler-Lagrange framework are evaluated, with the focus of highlighting the correct procedure for capturing the full gyroscopic couplings in linear EOMs. Monte Carlo simulations are performed on three scenarios, i.e. no aerodynamics, idling FOWTs and operational FOWTs. It is observed that gyroscopic couplings significantly influence the tower torsion (and possibly foundation yaw depending on the foundation type) of FOWTs without aerodynamic loads, and the spar-type FOWT is most sensitive to gyroscopic effects among the three concepts considered (although the TLP can be similarly sensitive). The aerodynamic loads are the dominating loads for both idling and operational FOWTs, and the gyroscopic effect becomes less significant although it still plays a more important role in operational FOWTs than idling FOWTs. Excluding the gyroscopic effect leads to non-negligible overestimation of the tower torsion of the operational FOWT. This study unfolds the correct derivation procedure, the mathematical formulas, the physical mechanism and the influence/significance regarding the gyroscopic effects in FOWTs, which also acts as a useful guideline for developing in-house reduced-order FOWT models.

Využití PET/ CT v diagnostice vzdálených metastáz a duplicitních nádorů v onkologii hlavy a krku PDF uzamčeno English info

Aim: Our goal was to assess our experience with accuracy of PET/ CT in the dia­gnostics of distant metastases and duplicity tumors in head and neck oncology. Methods: In total, 159 patients with a previously histologically verified malignant tumor of the head and neck underwent whole-body PET/ CT in our facility from 2016 to 2019. In 51 cases, we found out higher uptake of marked radiopharmaceutical (fluorodeoxyglucose) out of the head and neck region. In a retrospective study, we were evaluating the sensitivity and specificity of the method in the dia­gnostics of distant metastases and duplicities. Results: In our study, PET/ CT has sensitivity of 95.7% and specificity of 79.9% with positive and negative predictive values of 44.9% and 99.1% respectively. Conclusion: The method has a high sensitivity but lower specificity rate in the dia­gnostics of distant metastases (duplicity tumors) in head and neck oncology. Considering high radiation load and the price and availability of PET/ CT, it is necessary to consider the indication of this technique properly.

Generation of the current normal to the surface of antenna by electromagnetic waves and its application in the high responsive receiver

Generation of the initial current normal to the surface of antenna by electromagnetic waves has been considered. It has been shown that the angle of grazing (or sliding) for the wave with the electric vector in the plane normal to the surface varies the radiation resistance over a wide range. This property allows matching the radiation impedances and loads. Here, it has been proposed to use this property to create a highly- sensitive radiation detector. In relation with this task, a model of the radiation detection of the input radiation signal by a direct quadratic detector in the stationary mode with the diode included as the load has been considered. The obtained results prove that a diode with the high differential resistance can effectively operate with the antenna. The rise of the resistance increases the detector response voltage, its responsivity, and decreases the receiver noise equivalent power. Improvement of these characteristics by orders of magnitude is possible. The considered mechanism allows detectors to operate in the infrared spectral range, and the increase in the wavelength, in principle, does not limit its functioning.

Influence of the sag-to-span ratio on the dynamic response of a long-span bridge suspended from floating towers under wave and wind loads

ABSTRACT Long-span bridges suspended from floating towers are a promising design concept to cross the strait with deep water depth. This paper presents an alternative dynamic simulation framework for floating suspension bridge by integrating the calculations of wave, radiation and wind loads with common software and computing scripts, and verifies the numerical models, including structure, wave load, radiation and wind load. Bridge schemes with different sag-to-span ratios inspired by a prototype long-span floating bridge were proposed. Static, modal and dynamic analyses are conducted through the developed simulation framework to obtain the bridge response. The influence of the sag-to-span ratio on the dynamic response of a long-span bridge suspended from floating towers under wave and wind conditions was investigated. The results indicate that the natural period of the floating bridge decreases with the reduction in the sag-to-span ratio, and the sag-to-span ratio significantly affects the dynamic response of the example floating bridge.

Proton magnetic resonance spectroscopy as an alternative method for quantitative assessment of mineral bone density

Aims: 1) To evaluate an association between the fat fraction (FF) and bone mineral density (BMD) measured by localized proton magnetic resonance spectroscopy (1H-MRS) and quantitative computed tomography (QCT) densitometry, respectively, in healthy vertebrae of children after a compression fracture; 2) To compare the FF and BMD values with the severity of the compression vertebrae fractures.Materials and methods: Twenty (20) patients (aged 11.1±2.1 years) with a trauma-induced compression vertebral fractures participated in the study. The BMD of L3, L4 vertebrae (mg/cm3) was measured in by QCT (Philips Brilliance 16). FF in the same area was measured from 1H-MR-spectra (STEAM, echo time (TE)=12.8 ms, repetition time (TR)=3000 ms, voxel size=20×15×10 mm) using Philips Achieva TX 3.0T MRI scanner.Results: Correlation analysis revealed a significant inverse linear correlation (r=-0.55, p=0.0004) between FF and BMD of L3 и L4 vertebrae. In addition, in the patients with severe compression vertebral fracture (more than 2 fractured vertebrae) there was a significant increase in FF values and a BMD decrease, compared to the values in the patients with mild fractures (1–2 fractured vertebrae).Conclusion: The correlation suggests that the increase of FF in the bone marrow and the decrease of BMD in children go in parallel. Therefore, 1H-MRS could be an alternative to QCT and dual-energy X-ray absorptiometry. The absence of radiation load allows for recommendation to use 1Н-MRS for screening and follow-up, as well as for the control of BMD.

Do low dose CT-KUBs really expose patients to more radiation than plain abdominal radiographs?

Urolithiasis patients often require frequent urinary tract imaging, leading to high radiation exposure. CT Kidney-Ureter-Bladder (CT-KUB) is the gold standard in urolithiasis detection, however it is thought to harbour significant radiation load. Urologists have therefore utilised abdominal radiographs (XR-KUB) as an alternative, though with markedly lower sensitivity and specificity. We present the first contemporary UK study comparing the effective doses of XR-KUBs with low dose CT-KUBs. Fifty-three patients were retrospectively identified in a single centre who underwent both a XR-KUB and a CT-KUB in 2018. Effective-Dose was measured by converting the recorded 'Dose Area/Length Product' via the International Commission on Radiological Protection formula. The average effective dose of XR-KUBs and low dose CT-KUBs were 5.10 mSv and 5.31 mSv respectively. Thirty-four percent (18/53) of patients had a XR-KUBs with a higher effective dose than their low dose CT-KUB. Patients with higher Weight, BMI and AP diameter had higher effective doses for both their XR and low dose CT-KUBs. All patients in our study weighing over 92 kg or with a BMI greater than 32 had a XR-KUBs with a higher effective dose than their low dose CT-KUB. This data supports moving away from XR-KUBs for the investigation of urolithiasis, particularly in patients with a high BMI.

Thermal Radiant Cooling System Using Recycled Water from Swimming Pool

Global warming has an impact on the high room temperature, that can cause excessive use of air conditioning (energy). This directly give contribution not only on the high electricity usage but also energy consumption which is related to the decreasing environmental quality (greenhouse gases emission). In this study, the main concern is to see the potential in maximizing the role of recycled water as air conditioning elements for cooling system. The recycled water referred to this study is the used water originating from the swimming pool area, in which the pool itself acts as a part of the recirculating water system. The system consists of pipe grids in different lengths and widths in suspended ceilings or concealed has possibility to adjust the heat radiation from tempered walls directly to the room. The pipe grids itself serves as a cooling agent. This research was conducted adopting basic equations for radiant heat transfer, the equations makes it easier when application in the field so it can be used to determine the cooling effect produced. Calculation method conducts analysis to the surface of the panel which was exposed to the radiation load which would then be transfered by recycled water from swimming pool. The calculation method obtained through this study is expected to be used as a reference in recycled water for the cooling system to the room. An assumption calculation is done to see the potential of the radiant panels surface cooling efficiency, particularly by looking from the pipe type variable aspect that showed Copper with a surface cooling efficiency value of 3,080 should be used as pipe type for future research with purpose to achieve a higher surface cooling efficiency without cost limitation. This research was carried out by adopting various methods that can overcome ecological problems so that the results will not only provides comfort for the user of the room, but also as a reference for environmentally friendly building designs.

Experience and prospects of using robotics in the nuclear power industry

It is impossible to imagine the modern nuclear power industry without the use of robotics. Monitoring of equipment and structures conditions, elimination of accidents and catastrophes consequences are wide application areas of robots that allow to reduce the radiation load on personnel. In the near future, the global nuclear power industry will inevitably face the need to decommission nuclear power plants that were built in the 1970s-1980s, which currently form the core of nuclear generation. This determines the high relevance and importance of developing scientifically grounded methods and approaches to decontamination and dismantling of nuclear power plant radioactive structures with the preferential use of robotic technology. A review of domestic and international experience in the use of industrial and specialized robots in the field of nuclear energy allows us to assess the state and prospects of this direction, as well as to recognize the discrepancy between the existing technological level of robotic means and the promising tasks in the field of decommissioning of industrial nuclear reactors. In this case, it is considered appropriate and relevant to rapidly develop robotics as well as information simulation models that allow to provide various scenarios for dismantling of radioactive structures and equipment with the greatest involvement of modern robotic systems in this process.

Thermal Model for Timber Fire Exposure with Moving Boundary

Fire exposure of timber leads to charring, surface cracking and timber burnout, shifting the external thermal load deeper into the timber domain. This phenomenon plays its role mainly in situations of longer fire exposure. The majority of current approaches and models assume initial geometry during the whole analysis, leading generally to the overestimation of the insulation effect of the charred layer and to a limited burnout. This paper presents a heat transport model which is supplemented with a moving boundary condition, a criterion for the finite element deactivation and the internal heat source. Comparison with experiments using a constant radiative load testifies that the moving boundary condition becomes important after approximately 10 min of fire exposure and rather leads to a constant charring rate observed in several experiments.

APPLICATION OF SUPERMC3.2 TO PRELIMINARY NEUTRONICS ANALYSIS FOR EUROPEAN HCPB DEMO

In the D-T fueled tokamak, the neutrons not only carry the approximately 80% energy released in the per fusion reaction, but also are the source of radioactivity in the fusion system. Therefore, high-fidelity neutronics simulation is required to support such reactor design and safety analysis. In the present work, taking European HCPB DEMO (Helium Cooled Pebble Bed demonstration fusion plant) developed by KIT (Karlsruhe Institute of Technology) as an example, the preliminary neutronics analysis covering the assessments of NWL (neutron wall loading), TBR (tritium breeding ratio), nuclear power generation, radiation loads on PFCs (plasma-facing components) and TFCs (toroidal field coils) has been carried out by using SuperMC in the case of both unbiased and biased simulations. The preliminary results indicate that the blanket scheme could satisfy the design requirements in terms of TBR and shielding of inboard blankets. Specially, a speed-up by ~164 times in the calculation for thick shielding region (TFC region) is achieved by using global weight windows generated via GWWG in SuperMC. In addition, compared to MCNP, SuperMC shows advantages in accurate and efficient modeling of complex system, efficient calculation and 3D interactive visualization.

Algorithm for constructing an organizational and technological model for dismantling NPP buildings

In coming decade the practical implementation of work on the decommissioning of nuclear power plants will begin. Failure to take into account the decommissioning stage for NPPs of the first generations, the presence of a radiation component in the building structures of NPP buildings and structures, the need to destroy protective barriers are the main problems in the issue of dismantling works. The destruction of barriers and the specifics of dismantling technological processes can lead to the release of radioactivity into the environment, which will lead to an increase in the radiation load on personnel and the population. Radioactive contamination of structures leads to the formation of a large volume of radioactive waste, the amount of which can be significantly reduced due to the competent separation of waste into classes, taking into account the holding time. In this study the design of the reactor building for unit 1 of the Novovoronezh NPP was considered. Based on the analysis of the data of the comprehensive engineering and radiation surveys (CERS), which was completed in 2004, a classification of buildings into three groups was proposed. Based on the results of CERS, the dependences of the total activity of the main radionuclides and the cost of maintaining the block under observation from time are presented. As a result of the performed studies, an algorithm for constructing an organizational and technological model for dismantling buildings and structures of NPP that are being decommissioned is proposed.

Актуальные проблемы ядерной медицины в педиатрии (обзор)

On the basis of literature data and personal experience, the current state and prospects for the development of nuclear medicine in pediatrics are analyzed. The main directions of radionuclide diagnostics and radionuclide therapy in children are briefly considered. The importance of accu-rate determination of the optimal value of the activity of a specific radiopharmaceutical adminis-tered to a child, taking into account his body weight and the study protocol, was noted. A tendency for an increase in the radiation load on patients is shown due to the widespread introduction into clinical practice of hybrid installations for radionuclide studies, when using which the dose of in-ternal radiation from radiopharmaceuticals is supplemented by the dose of external radiation from X-ray CT. The need to take into account the risk of radiation-induced carcinogenesis in nu-clear medical procedures, the probability of which in children is significantly higher than in adults, is emphasized. The technological and psychological features of these procedures in children are discussed. The necessity of substantial revision of domestic normative documents regulating the use of means and methods of nuclear medicine in pediatrics has been substantiated.

Пригнічення післяімпульсних коливань в активних випромінюючих антенах типу Bow Tie

Subject and Purpose. This theoretical and experimental research is devoted to peculiarities of the ultra-wide bandwidth (UWB) pulse radiation from active bow-tie dipoles. The focus is on the relationship between the amplitude-time dependences of electromagnetic fields produced by active UWB pulsed antennas and the configuration of the conductive components for temporally short (less than 0.5 ns), ultra-wide-bandwidth pulse radiation. Methods and Methodology. Analysis of the radiator geometry action on the emitted pulse parameters is performed by numerical simulation with the use of the finite-difference time-domain (FDTD) method. The experiment involves specially made, variously shaped bow-tie radiators tested with different resistive loadings in radiation mode. The numerically simulated characteristic curves of the radiated field amplitude shape versus radiator geometry are confirmed by experiment. Radiation field parameters versus load resistance are experimentally studied, too. Results. Conditions for the effective pulse radiation with a largest-possible pulse amplitude have been determined, the post-pulse oscillation amplitude and duration reduced to a minimum. Conclusion. It has been shown that the resistive loading in the excitation area significantly reduces amplitudes and durations of post-pulse oscillations in signals radiated by active dipole antennas.

PV-STATCOM in Photovoltaic Systems under Variable Solar Radiation and Variable Unbalanced Nonlinear Loads

The paper focuses on an efficient method to compensate the harmonics and zero-sequence component caused by the variable unbalanced nonlinear loads. The studied compensator is based on the conventional Static Compensator (STATCOM) which is supplied by a photovoltaic generator rather than the storage passive components. That constitutes a Photovoltaic Static Compensator (PV-STATCOM). In addition to the active power production, this PV-STATCOM will improve the quality of the electric grid highly disturbed without any additional devices and costs. The used control strategy is based on the instantaneous power method and current control. The obtained results show the benefits of the photovoltaic active filter compensator to improve the energy quality. Specially, the Total Harmonic Distortion (THD) is decreased from 28.80 % to 2.03 %. The zero-sequence component of the load currents is reduced from 31.50 % to 4.26 %. The results prove also a high stabilization and limitation of the harmful repercussions of the compensator on the photovoltaic station and an automatic adapting to the solar variable radiation and to the unbalanced nonlinear load variations.

A New Online Learned Interval Type-3 Fuzzy Control System for Solar Energy Management Systems

In this article, a novel method based on interval type-3 fuzzy logic systems (IT3-FLSs) and an online learning approach is designed for power control and battery charge planing for photovoltaic (PV)/battery hybrid systems. Unlike the other methods, the dynamics of battery, PV and boost converters are considered to be fully unknown. Also, the effects of variation of temperature, radiation, and output load are taken into account. The robustness and the asymptotic stability of the proposed method is analyzed by the Lyapunov/LaSalle's invariant set theorems, and the tuning rules are extracted for IT3-FLS. Also, the upper bound of approximation error (AE) is approximated, and then a new compensator is designed to deal with the effects of dynamic AEs. The superiority of the proposed method is examined in several conditions and is compared with some other well-known methods. It is shown that the schemed method results in high performance under difficult conditions such as variation of temperature and radiation and abruptly changing in the output load.

Radiation damage modeling of austenitic steels for cyclic loading

Prediction of material behaviour under different loading situations involve a multifaceted concept of mechanics. To predict the material behaviour of the components operating under a radioactive environment such as that in nuclear power plant or in space applications, the effect of radiation should be accounted. Industrial steels components when exposed to radiation undergo radiation embrittlement, which is highly undesirable. The present work is aimed to predict the behaviour of industrial grade steel under monotonic and cyclic loading considering the effect of radiation load. The material behaviour under monotonic loading for non-irradiated and irradiated specimen is compared with the published experimental results. Further, the cyclic behaviour is predicted using the validated model to demonstrate the significance of incorporating the radiation hardening terms in the constitutive model to consider for the radiation hardening effect.

SKIN AND SUBCUTANEOUS ADIPOSE TISSUE DAMAGE AFTER RADIATION THERAPY IN BREAST CANCER PATIENTS.

The analysis of long-term researches of the pathological changes arising in soft tissues at patients with a breast cancer as a result of radical surgical treatment and adjuvant radiotherapy is carried out in work. The article shows that the standard approach to postoperative radiation therapy, which is based only on the prevalence of the primary tumor process is not always justified. Very often it leads to excessive radiation load on the patient's body and the development of local acute and chronic radiation reactions of the skin, subcutaneous tissue and other soft tissues.In this regard, the question of differentiated purpose of radiotherapy acquires special value first of all at patients with small primary prevalence of tumor process. The paper presents the results of studies to study changes in the anterior chest wall in patients with breast cancer. In relation to the conduct of adjuvant radiotherapy more often need to use the concept of personalized radiation therapy. Radical operation, post-radiation early and late pathological changes in soft tissues, disturbance of microcirculation of lymph and blood, disturbance of innervation of vessels of an upper extremity, peripheral nerves in system of a cervical and plexus plexus, leads to intensive degen-erative and dystrophic changes in soft tissues of the upper. and causes morphological changes in them and further progression of reflex neurovascular and neurodystrophic disorders. Based on the data of adverse effects of radio-therapy on the skin and surrounding tissues, as well as to reduce excessive radiation exposure to the patient's body, a differentiated approach to the appointment of adjuvant radiation therapy.

A new approach to the development of perspective compact frequency multipliers of the subterahertz and terahertz bands for on-board electronic equipment

Currently, the increasing interest of researchers is attracted by the theoretical and practical problems of mastering the sub-terahertz and terahertz frequency range. Electronic devices operating in these ranges find effective applications in various fields of science and technology: aerospace equipment, security systems, spectroscopy, medicine, biology and many others. The purpose of this work is to focus on a frequency multiplication device that allows using basic sources of relatively low frequency generation to enter the terahertz frequency range. The results of recent years obtained both on the basis of solid-state effects and with the help of vacuum electronics, in particular, magnetron-type devices, which are characterized by compactness, high resistance to radiation loads, mechanical influences, which is important for on-board equipment, are considered. It is known that at high frequencies, vacuum devices require super-precision manufacturing of decelerating systems. This is essentially the main difficulty. The article proposes a new approach based on the hypothesis of P.L. Kapitsa, which allows to significantly simplify the anode structure of a magnetron multiplier with an acceptable level of output parameters. The achievements of recent years in the field of creating sub-terahertz and terahertz frequency multipliers, mainly for on-board equipment of mobile platforms, taking into account the requirements of aerospace systems, first of all, are noted.

Inner radiation belt simulations of the proton flux response in the South Atlantic Anomaly during the Geomagnetic Storm of 15 May 2005

A test particle simulation code was developed to simulate the inner proton belt response during the intense geomagnetic storm of 15 May 2005. The guiding center model was implemented to compute the proton trajectories with an energy range of 70–180 MeV. The time-varying magnetic field model implemented in the simulations was computed by the Tsyganenko model TS05 with the associated inductive electric field. One of the most important features of the low-earth orbit (LEO) environment is the South Atlantic Anomaly, which imposes a dangerous radiation load on most LEO missions. This research aims to investigate the proton flux variations in the anomaly region with respect to space weather conditions. The results showed that during the main phase of the geomagnetic storm, the proton flux in the SAA decreased, whereas, throughout the initial and recovery phases, the proton flux was increased at most of the altitudes. Satellite measurements confirmed numerical results.

Understanding the Impacts of Land Cover Change on Water Quality in an Urbanized Stream

The heavily urbanized Johnson Creek watershed in the Portland, Oregon metropolitan region has experienced degraded water quality and historic mismanagement for decades. This paper reviews previous work on urbanized watersheds as well as studies that have explored Johnson Creek itself. Analysis of those previous studies is used to determine the present water quality within Johnson Creek and aims to predict how development and restoration will impact future water quality. While tracking water quality, stream temperature, total suspended solids (TSS), land cover metrics, extent of development, and canopy cover, this research expatiates on the effect of rising temperatures, the need for more responsive sediment transport, and increased spatial development within all portions of the watershed. Ultimately, this author has concluded that increased sunlight exposure through solar radiation loads on streams as a result of human-generated disturbances is a significant cause of stream temperature warming and the deterioration of water quality. Despite numerous and long-standing efforts for public-private cooperative stream restoration, the water quality in the Johnson Creek watershed continues to deteriorate.