Подавление синхронной помехи в ЯКР с модуляцией Зеемана

Рассмотрены принципы частотной модуляции и модуляции Зеемана в ядерном квадрупольном резонансе и показаны преимущества последней. Предложен метод устранения синхронной помехи, вызываемой переключением магнитного поля. Приведены результаты наблюдения резонансной линии ¹⁴N с достоверной формой в образце гексаметилентетрамине массой 2 г.Розглянуто принципи частотної модуляції та модуляції Зеемана в ядерному квадрупольному резонансі та показано переваги останньої. Запропоновано метод усунення синхронної завади, спричиненої перемиканням магнітного поля. Наведено результат спостереження резонансної лінії ¹⁴N з достовірною формою у зразку гексаметилентетраміну масою 2 г.The principles of frequency and Zeeman modulation in nuclear quadrupole resonance were considered, and the advantages of the latter were shown. The authors propose a method to eliminate the synchronous noise caused by switching of the magnetic field. Results of observations of the resonance line with ¹⁴N in the hexamethylenetetramine sample weighing 2 g were given

A review of the ecological effects of radiofrequency electromagnetic fields (RF-EMF)

Industrial EcologyEnvironmental Biolog

Estimation of focusing operators using the Common Focal Point method

The objective of this PhD project is to present a data-driven method to determine one-way focusing operators. Focusing operators are the input for imaging a subsurface structure from measurements at the surface. They can be used in imaging the earth's interior, and also in non-destructive imaging of e.g. wings of aeroplanes or in medical imaging for detection of uterus cancer. This thesis focuses on methods for the exploration seismology. Focusing operators are one-way propagation operators for acoustic wavefields describing the propagation from one subsurface point, the focal point, to the surface locations. They are often parameterised as traveltime operators and amplitude (weight) operators. The traveltime and the amplitude operators are estimated in a data-driven manner. No a priori information such as a velocity model is used. Using the Common Focal Point method a data-driven estimation strategy is found with implementations for different geologies. Mainly, the traveltime operator can be estimated by an iterative method based on the Principle of Equal Traveltime and the Data Matching Principle. Once the traveltime operator is found, the confocal reflection amplitudes for one single focal point for each source-receiver pair can be extracted from the shot records. These are displayed in a CFP matrix. The amplitude function can be represented as an eigenvector of the CFP matrix. The obtained operators are non-smooth containing all measured propagation effects, and therefore are capable of producing improved images and provide optimal input to tomographic methods.Applied Science

A framework for deciding on the inclusion of emerging impacts in life cycle impact assessment

As technology progresses, so does the concern about the potential health impacts on humans and biodiversity that go in hand with technological development. Emerging new impacts that are characteristic of the anthropocene require more attention in current life cycle assessment (LCA), a framework in which many relevant impact assessment models are still missing. More attention, more data and more concern require the LCA community to intervene and to start or increase the modelling efforts to accommodate new impacts in LCA. To date the process of inclusion of new impacts in LCA has not yet been formalised. To deal with this process, a framework is here proposed and tested through the analysis of three emerging impact categories, noise, ecological light pollution (ELP) and radio-frequency electromagnetic fields (RF-EMF). We show that any development must start from a careful study of the theories and investigations from other specialist fields of science than the field of LCA. The gathering of such information is fundamental to assess the maturity of the impacts, their importance and the quality of the evidence that is available. In addition, this information has to be bridged to the computational structure of LCA, to check whether the physical properties of new impacts may be adjusted to the basics of LCA. We discuss the three new potential impact categories as a paradigm for action for any new development in LCA. © 2014 Elsevier Ltd. All rights reserved

Electromagnetic field exposure in power plants: A qualitative assessment of work safety perceptions among employees

Electromagnetic fields, or EMF, are ubiquitous in our daily life. Extremely low frequency magnetic fields (ELF MF) are generated by any device using electric current. Especially in workplace situations involving MRI scanners, welding equipment, induction heaters, and power plants, they are known for potentially high field strengths. These high field strengths may lead to adverse health effects if insufficient preventive measures are in place. This study investigates employees’ perceptions on work safety regarding EMF exposure. We held 15 semi-structured interviews in three different (non-nuclear) power plants in the Netherlands. We found that power plants in this study made ample use of fences and warning signs where needed, creating a safe working environment. Nevertheless, some workers perceive that there are vague regulations, organizational issues and lack of clarity on the properties of EMF. Participants also indicated that there is some room for improvement with respect to work safety meetings on EMF. Employees want to be informed about EMF and its potential health effects and mitigation methods, but their information need is limited and straightforward. A simple warning system, along with safety information on paper, may be sufficient. https://doi.org/10.1080/13669877.2020.1750459 LinkedIn: https://www.linkedin.com/in/john-bolte-0856134

Particulate matter exposure in roadwork companies: A mental models study on work safety

Particulate matter (PM) exposure, amongst others caused by emissions and industrial processes, is an important source of respiratory and cardiovascular diseases. There are situations in which blue-collar workers in roadwork companies are at risk. This study investigated perceptions of risk and mitigation of employees in roadwork (construction and maintenance) companies concerning PM, as well as their views on methods to empower safety behavior, by means of a mental models approach. We held semi-structured interviews with twenty-two employees (three safety specialists, seven site managers and twelve blue-collar workers) in three different roadwork companies. We found that most workers are aware of the existence of PM and reduction methods, but that their knowledge about PM itself appears to be fragmented and incomplete. Moreover, road workers do not protect themselves consistently against PM. To improve safety instructions, we recommend focusing on health effects, reduction methods and the rationale behind them, and keeping workers’ mental models into account. We also recommend a healthy dialogue about work-related risk within the company hierarchy, to alleviate both information-related and motivation-related safety issues. https://doi.org/10.1016/j.ssci.2019.06.043 LinkedIn: https://www.linkedin.com/in/john-bolte-0856134

Ecological momentary assessment study of exposure to radiofrequency electromagnetic fields and non-specific physical symptoms with self-declared electrosensitives

The main objective of the study is to determine if non-specific physical symptoms (NSPS) in people with self-declared sensitivity to radiofrequency electromagnetic fields (RF EMF) can be explained (across subjects) by exposure to RF EMF. Furthermore, we pioneered whether analysis at the individual level or at the group level may lead to different conclusions. By our knowledge, this is the first longitudinal study exploring the data at the individual level. A group of 57 participants was equipped with a measurement set for five consecutive days. The measurement set consisted of a body worn exposimeter measuring the radiofrequency electromagnetic field in twelve frequency bands used for communication, a GPS logger, and an electronic diary giving cues at random intervals within a two to three hour interval. At every cue, a questionnaire on the most important health complaint and nine NSPS had to be filled out. We analysed the (time-lagged) associations between RF-EMF exposure in the included frequency bands and the total number of NSPS and self-rated severity of the most important health complaint. The manifestation of NSPS was studied during two different time lags - 0–1 h, and 1–4 h - after exposure and for different exposure metrics of RF EMF. The exposure was characterised by exposure metrics describing the central tendency and the intermittency of the signal, i.e. the time-weighted average exposure, the time above an exposure level or the rate of change metric. At group level, there was no statistically significant and relevant (fixed effect) association between the measured personal exposure to RF EMF and NSPS. At individual level, after correction for multiple testing and confounding, we found significant within-person associations between WiFi (the self-declared most important source) exposure metrics and the total NSPS score and severity of the most important complaint in one participant. However, it cannot be ruled out that this association is explained by residual confounding due to imperfect control for location or activities. Therefore, the outcomes have to be regarded very prudently. The significant associations were found for the short and the long time lag, but not always concurrently, so both provide complementary information. We also conclude that analyses at the individual level can lead to different findings when compared to an analysis at group level. https://doi.org/10.1016/j.envint.2019.104948 LinkedIn: https://www.linkedin.com/in/john-bolte-0856134

Prima vera: Synergising predictive maintenance

The full potential of predictive maintenance has not yet been utilised. Current solutions focus on individual steps of the predictive maintenance cycle and only work for very specific settings. The overarching challenge of predictive maintenance is to leverage these individual building blocks to obtain a framework that supports optimal maintenance and asset management. The PrimaVera project has identified four obstacles to tackle in order to utilise predictive maintenance at its full potential: lack of orchestration and automation of the predictive maintenance workflow, inaccurate or incomplete data and the role of human and organisational factors in data-driven decision support tools. Furthermore, an intuitive generic applicable predictive maintenance process model is presented in this paper to provide a structured way of deploying predictive maintenance solutions

Electrochemical Characterization of Low Temperature Thermal Aging Embrittlement of Stainless Steel 304L Weld

Abstract. Thermal aging embrittlement of type 304L stainless steel weld is investigated on the basis of changes in microstructure, microhardness and electrochemical behavior after aging up to 20,000 h at 335, 365 and 400 °C. Spinodal decomposition and G-phase precipitation in the ferrite was observed after thermal aging. Aging led to increase in the hardness of ferrite phase while there was no change in the hardness of austenite. The changes in electrochemical behavior due to aging were studied using double loop electrochemical potentiokinetic reactivation (DL-EPR) test. Aging led to increase in the DL-EPR value which is attributed to Cr depletion in the ferrite phase