Operational Experience Research Articles

The FIRE-IN project: Tsunami-risk related practitioner challenges and 3rd cycle overall results.

This article summarizes the methodology for the identification of practitioners' challenges, in the context of the H2020 funded project FIRE-IN (Fire and Rescue Innovation Network) activities. The project consisted of five thematic areas or "Thematic Working Groups", as they are called, i.e., Search and Rescue Emergency Response, Structure Fires, Landscape Fires Crisis Mitigation, Natural Hazard Mitigation and Chemical Biological Radiological Nuclear and Explosives, and three iterations, each one including the identification of capability challenges, the screening for solutions, that can potentially address these challenges, and the request for ideas regarding future innovations that will complement already existing ones and will assist in covering capability gaps. This article focuses on the natural hazard mitigation working group and tsunamis in the Mediterranean region as a case study for the 3rd and last iteration of the project. The scenario of a tsunami occurrence in the Mediterranean is the basis for the FIRE-IN 3rd cycle workshop, as an indicative example of a high impact - low probability event, which aims to identify practitioners' Future Common Capability Challenges in Europe. The current status of the tsunami hazard in Europe, national and international tsunami risk mitigation measures and procedures and operational experience from recent events are also discussed. Focus is provided on the natural hazard mitigation and tsunami related practitioners' challenges, while results from the FIRE-IN request for ideas process and the interaction between practitioners, researchers and industry are also discussed. The aim is to present practitioners' current and future capability challenges , one of the main outcomes of the FIRE-IN project, and to provide further guidelines to stakeholders of disaster management towards a safer Europe, mainly, through preparedness and adaptation for stronger and resilient societies.

When citizen science meets radon building diagnosis: Synthesis of a French pilot project developed in the framework of the European RadoNorm research project.

As part of the European RadoNorm research project, citizen science pilot projects focusing on the management of radon risk in houses have been implemented in four countries. This article describes the methodological basis, the development and the results of the French pilot project. Building on an initial review of existing literature, the pilot project aims to frame a 'participatory approach' aligned with the standards and recognized practices of citizen science. Particular attention was given to the management of data and the inclusion of ethical considerations. The focal point of the project was the process of radon building diagnosis which is supposed to be carried out whenever (high) radon concentrations are measured and should be prerequisite to mitigation works. As experience shows, however, this diagnosis is hardly implemented in France. To help remedy this situation, the pilot project recruited citizens already aware about radon from Pays Vesoul Val-de-Saône (East of France) to test an existing online self-evaluation guide for radon diagnosis, report on their operational experience and meet with radon/building experts. This enabled citizens to contribute to improvements in form and content to the guide and to ensure that it would be better fit for purpose. Comparison of the guide with experts' practices offered additional perspectives on what building diagnosis should entail. The pilot project produced rich and high-quality data that will nurture the evolution of the guide. The project demonstrated both the viability and the utility of applying the citizen science approach to radon post-measurement phases, with measurable benefits in bridging knowledge gaps and in encouraging behavioural changes. The results of using a citizen science approach in the field of radon management and research are encouraging, and they far outweigh the challenges involved in the implementation.

Operational and engineering experiences of gas injection to JET for TT and DT operational campaigns

Following the first deuterium–tritium experiment (DTE1) at UKAEA, modifications were investigated to the Joint European Torus’ (JET) gas introduction (GI) systems to increase the gas feed capabilities of the JET facility to better support future campaigns. The GI systems comprise the GI and gas distribution system in the Active Gas Handling System (AGHS), and neutral beam injection and the tritium injection modules on the torus. During DTE1 about 100 g of tritium was supplied from AGHS to JET users. During the second deuterium–tritium experiment (DTE2) and the tritium–tritium experiment (TT) just over 373 g and 630 g of tritium respectively was supplied to JET users for the campaigns. The tritium and deuterium gas supply systems of the fuel cycle can be underestimated as having fewer technical or scientific challenges based on the mechanical simplicity of equipment that they consist of. However, operational experience has shown these systems have the potential to bottleneck a campaign programme. This publication outlines the upgrade requirements foreseen, following DTE1, for operations in the DTE2 and TT campaigns, how these changes impacted the gas supply operations, and where limitations were encountered. The areas discussed include—challenges of upgrading and maintaining equipment designed for a short operating life; the impact of having differences between user requirements and gas supply capabilities; the logistics of gas supply involving multiple control room locations; communication routes between gas supply systems and teams; and safely controlling and tracking tritium gas movements. The latest JET tritium campaigns highlighted a number of challenges for future facilities looking to operate in both batch and continuous gas injection operational modes. The recommendations from this publication intend to provide a starting point for how to address these challenges and optimise gas supply in support of future fusion programmes. This work has been carried out within the framework of the contract for the operation of the JET Facilities and has received funding from the European Union’s Horizon 2020 research and innovation programme. The views and opinions expressed herein do not necessarily reflect those of the European Commission.

Design of a new kind of chemical experiment container with virtual reality fusion

BackgroundAt present, the teaching of experiments in primary and secondary schools is affected by cost and security factors. Existing research on virtual experiment platforms has alleviated these problems. However, the lack of real experimental equipment and use of a single channel to understand user intentions weaken these platforms operationally and degrade the naturalness of interactions. MethodsTo solve these problems, we propose an intelligent experimental container structure and a situational awareness algorithm, both of which are verified and applied to a chemical experiment involving virtual-real fusion. First, the acquired images are denoised in the visual channel using the maximum diffuse reflection chroma to remove overexposure. Second, container situational awareness is realized by segmenting the image liquid level and establishing a relation-fitting model. Then, strategies for constructing complete behaviors and making priority comparisons among behaviors are adopted for information complementarity and independence, respectively. A multichannel intentional understanding model and an interactive paradigm that integrates vision, hearing, and touch are proposed. ResultsThe experimental results show that the accuracy of the intelligent container situation awareness proposed in this paper reaches 99%, and the accuracy of the proposed intention understanding algorithm reaches 94.7%. The test shows that the intelligent experimental system based on the new interaction paradigm also has better performance and a more realistic sense of operation experience in terms of experimental efficiency. ConclusionThe results indicate that the proposed experimental container and algorithm can achieve a natural level of human-computer interaction in a virtual chemical experiment platform, enhance the user′s sense of operation, and achieve high levels of user satisfaction.

Debris Management in Turkey Provinces Affected by the 6 February 2023 Earthquakes: Challenges during Recovery and Potential Health and Environmental Risks

On 6 February 2023, southeastern Turkey was struck by two major earthquakes that devastated 11 provinces. Tens of thousands of buildings collapsed and more were later demolished. During post-event field surveys conducted by the authors, several disposal sites set up in the most affected provinces were detected and checked for suitability. Based on field observations on the properties of sites and their surrounding areas as well as on the implemented debris management activities, it is concluded that all sites had characteristics that did not allow them to be classified as safe for earthquake debris management. This inadequacy is mainly attributed to their proximity to areas, where thousands of people reside. As regards the environmental impact, these sites were operating within or close to surface water bodies. This situation reveals a rush for rapid recovery resulting in serious errors in the preparation and implementation of disaster management plans. In this context, measures for effective debris management are proposed based on the existing scientific knowledge and operational experience. This paper aims to highlight challenges during earthquakes debris management and related threats posed to public health and the environment in order to be avoided in future destructive events.

Possibility of misleading readings of water level in VVER steam generator during severe accidents with account for the Fukushima lessons

The severe accident at Fukushima Daiichi in 2011 has emphasized the importance of keeping instrumentation reliable in the course of a severe accident, for successful diagnosis of current state of the reactor and adequate decision making. After the electrical current was partially restored several hours into the accident at Unit 1, the readings of the water level in the core have been for a long time misleading. Given the conditions at the Unit, they were clearly contradicting the analytical estimates of coolability and degradation level of the reactor core. In the post-accident investigations this contradiction was explained by TEPCO by the effect of water evaporation in the reference leg due to heat up of the drywell atmosphere around. The water level instrumentation in different vessels of the VVER NPPs like steam generator, pressurizer is very similar to that at Fukushima BWR. Although the VVER and BWR designs are different in many aspects, it is important to verify if the lessons learnt from the Fukushima accident are applicable in case of severe accidents at VVER.This paper presents the results of numerical study for the possibility of misleading readings of water level in VVER steam generator during hypothetical severe accidents. These results demonstrate the importance of learning the lessons from the accidents that have happened at structurally similar NPPs, and their consideration in safety analyses of NPP units in operation and under design process. Accumulation of lessons learnt from previous operation and emergency experience is a very important advantage of nuclear fission technology that allows enhancing the safety of new designs of nuclear reactors.

A Critical Review of the Proposed Hyperloop (Ultra-High-Speed Rail) Project between Mumbai and Pune and Its Broader Implications for Sustainable Mobility in Indian Cities

This review paper examines the appropriateness of a hyperloop line between Mumbai and Pune in India, examining, in particular, its potential economic implications and impact on people. This assessment builds on an earlier in-depth examination by the authors of the key urban and transport planning, technical, environmental, economic and human factors surrounding the hyperloop technology. The current detailed analysis of hyperloop’s expected implications in the Mumbai to Pune corridor is based upon use of a wide variety of existing indicative data from many sources, which are sufficient to provide a very broad “first-step” reality testing of hyperloop’s suitability to India. It could be argued that this is precisely the kind of analysis that should have been conducted, or at least made public, prior to committing to hyperloop in India. The paper highlights many negatives concerning hyperloop’s construction and operation, including a very high capital cost compared to other needed urban transport infrastructure projects in India, a potential lack of patronage due to a range of factors and its potentially exclusive upper income patronage cohort. It is concluded that rather than making a costly mistake, India should address current urban mobility challenges and needs such as bus rapid transit (BRT) and metros in its innumerable cities, whose construction costs are vastly lower than the expected cost of a single hyperloop line. Technology, such as the hyperloop, would need time to mature and gain operational experience. Should any corridor be found suitable, there would still need to be a thorough, detailed benefit–cost analysis together with a dedicated examination of the technology’s broader urban planning implications and less tangible factors. Setting aside the ultimate worthiness of hyperloops, India would need to at least achieve certain preconditions before proposing or pursuing such systems in the country.

Relationship between Multiplier, Employee Job Attitude, and Employee Engagement

Nowadays, with the rapid development of the business sector and increasing competition, the significance of effective leadership in managing business organizations has escalated significantly. In this fiercely competitive environment, it is imperative for leaders to recognize and respond to the emotions of their employees. Consequently, they need to place great emphasis on employee attitudes, satisfaction, loyalty, and engagement. This study aims to examine the correlation between the multipliers which is a new style of modern leadership, employee job attitudes, and employee engagement. The research encompassed a survey administered to employees of a well-established trade and services company with over two decades of operational experience. Quantitative data were processed using software tools such as SPSS 23.0 and Smart PLS 4.0, which are extensively employed in social science research. A total of 85 employees participated in the study, and for verification and testing the proposed hypothesis in the study, we conducted various statistical analyses inclusive of factor analysis, reliability analysis, correlation analysis, and structural equation models (SEMs). According to the results of the analysis, it was shown that a significant and positive influence of multiplier on both employee job attitude and employee engagement. Furthermore, employee job positive attitude leads to an increase in employee engagement. Additionally, the study's results indicate a noteworthy finding: it was observed that employee job attitude plays a mediating role in the relationship between the multiplier and employee engagement.

Operational experiences of chemical-looping combustion with 18 manganese ores in a 300W unit

Chemical-looping combustion is a novel combustion technology with inherent CO2 capture. The process uses oxygen carriers in the form of metal oxide particles to transfer oxygen from air to fuel. The particles make up the bed material in two fluidized-bed reactors, the air reactor and the fuel reactor, and circulate between the two reactors. Natural minerals of low cost are attractive as oxygen carriers in chemical-looping combustion (CLC), in particular when used for combustion of solid fuels. The presence of ash can restrict the effective lifetime of the oxygen carrier either by loss of bed material associated with the ash removal or by direct reactions between ash and oxygen carrier that impair its reactivity. Independent of the presence of ash, the oxygen carrier lifetime can be limited by attrition leading to loss of fines.Ores considered and used in chemical-looping combustion include ilmenite, iron ore and manganese ore. Manganese ore is the least tested of these, although several studies suggest manganese ores often have higher reactivity as compared to the other two. The present study compares data from operation of 18 different manganese ores in a 300 W chemical-looping combustor, involving 329 h of operation with fuel. Results for 10 of these, involving 148 h of operation, have previously not been published. Some of these manganese ores have also been used in larger pilots, as well as in a 10 MW circulating fluidized-bed boiler.Operational results indicate significant differences between the ores with respect to performance, with syngas conversion ranging between 80 and 100% and methane conversion ranging between 17 and 59% and attrition rates ranging from very high to as low as 0.05%/h. For a few ores formation of fines led to operational failure after only a short period with fuel and for one of the ores agglomeration led to failure.The correlation between performance data and oxygen-carrier characteristics, including elementary analysis, was assessed. Gas conversion for both syngas and methane were correlated to gas conversion in lab testing. However, neither jet cup attrition data nor crushing strength was correlated to attrition in 300 W. This suggests that the mechanisms causing attrition are different at hot conditions and with reactions taking place, which emphasizes the need for pilot testing in the screening of manganese ore oxygen carriers.Fortunately, the correlation between gas conversion and attrition was weak. Thus, high reactivity is not necessarily associated with low attrition assistance and vice versa and several ores show high reactivity in combination with low or moderate attrition. Consequently, screening of manganese ores is well worth while, in order to find materials that can give both high conversion and long life-time. The best four ores were the Chinese Guizhou, South-African UMK, Elwaleed B, and Sibelco´s Braunite having syngas conversion(%)/attrition rate(%/h) of 98.3/0.05, 100/0.33 100/0.5 and 96.7/0.12, respectively.

MILITARY GEOLOGY: AN AMERICAN TERM OF WORLD WAR I RE-DEFINED FOR THE BRITISH ARMY AT THE END OF WORLD WAR II

ABSTRACT The term ‘military geology’, translated from German after earlier use in French and Spanish publications, entered the English language via American publications from 1917 onwards, initially after the USA entered World War I. It was widely used in the USA and, in direct or indirect translation, in several European countries additional to Germany and Austria thereafter, but not in the United Kingdom—although military applications of geology had been perceived and utilized by the British Army for much of the previous century. However, the term was used and its scope defined on the basis of operational experience at a meeting in Brussels on 28 February to 1 March 1945 as World War II drew to an end, a meeting seemingly unique for the War in that it comprised five ‘British’ geologist officers of field rank: the South African Major Gordon Lyall Paver, English Major Frederick William Shotton, Australian-born but Canadian-educated English Major John Leonard Farrington, English Squadron Leader John Francis Kirkaldy, and Welsh Major David Ronald Arthur Ponsford. Their purpose was to review wartime use of ‘military geology’ in the British Army, and to make recommendations for a more efficient British military geological service in the future, especially in the Far East after the war in Europe entered its final phase. The meeting generated a four-page closely-typed unpublished ‘Memorandum: Military geology in the British services’ (now preserved in England in the Lapworth Museum at the University of Birmingham and in The National Archives, Kew, near London). This included a very brief summary of the British Army’s deployment of geologists within western Europe, East Africa, the Middle East, North Africa and the Mediterranean region, and India. Those present brought together long experience from all these campaign areas except India (and the Far East in general). That deficiency was made good later in the year, on 7 December 1945, when Eric J. Bradshaw, Superintending Geologist of the Strategic Branch of the Geological Survey of India, completed an 81-page typed unpublished ‘Military geology: Memorandum of post-war policy’ (accessible in England at Birmingham, at Kew, and at the British Geological Survey, Keyworth). This with its 23 pages of appendices records details of wartime work in India and discussions held by the author there and in the United Kingdom following the end of hostilities in Europe on 8 May 1945. It re-defines the scope of ‘military geology’ for British armed forces in terms of water (resources, floods and drainage), stone and miscellaneous mineral resources, soils, engineering projects (reconnaissance, stability and excavations), terrain, ‘photo-geology’ and several miscellaneous applications. The memorandum proposed a grandiose organization of 151 geologist officers plus ancillary staff for British military geology postwar. That organizational scheme was not adopted—but by 1945 the term ‘military geology’ had clearly extended from American to significant British use.

DIGITAL TRANSFORMATION OF BUSINESS

In the conditions of the digital economy, managers face new tasks, and their roles and principles of business management are changing. In particular, they face the question: what technologies and principles of the digital economy must be implemented? The article outlines the main problems of the management organization of the company that arise in the conditions of business digitalization. The paper analyzes international standards and research that are directly related to the organization of the management process in companies.In the course of the study, the main shortcomings associated with the implementation of digital technologies were identified, which include, in addition to possible risks of data security violations, and social issues associated with a possible reduction in the number of personnel. The article notes that all these problems can contribute to the loss of the company's reputation and trust in it.In today's conditions, the digitization of the organization's management processes requires the restructuring of its entire management system and the development of standards necessary for effective management, therefore, the use of existing own experience and knowledge necessary for the profitable operation of the company in the conditions of digitalization of the economy is relevant.

Comparative study of a glovebox dismantling facility for manual and remote glovebox dismantlement activities

A giant glovebox-type facility called the glovebox dismantling facility was developed at the Plutonium Fuel Production Facility, Japan Atomic Energy Agency, in 1995 to dismantle heavy hold-up gloveboxes and recover nuclear materials from them, which was a concerning international issue in the mid-1990s. The facility allowed conducting remote glovebox dismantlement using remote devices installed in the facility as well as the conventional manual glovebox dismantlement by workers wearing air-fed suits and manually operating hand tools. The facility was operated from 1996 to 2000 for dismantling heavily contaminated equipment gloveboxes and operated from 2001 to 2006 for the technological development of glovebox dismantlement, including work segment data recording and remote method testing. This study presents the features and brief history of the facility and the primary dismantlement results. Subsequently, we evaluate the novelties of the facility from operational experiences in manual and remote glovebox dismantlement methods and discuss their characteristics. Furthermore, we evaluate the worker exposure dose based on the obtained data and confirm that the remote method considerably reduced the worker exposure dose. Finally, we show how these experiences are effectively fed back to the technological dismantlement development for our old glovebox facility decommissioning project.

When citizen science meets radon building diagnosis: Synthesis of a French pilot project developed in the framework of the European RadoNorm research project

As part of the European RadoNorm research project, citizen science pilot projects focusing on the management of radon risk in houses have been implemented in four countries. This article describes the methodological basis, the development and the results of the French pilot project. Building on an initial review of existing literature, the pilot project aims to frame a ‘participatory approach’ aligned with the standards and recognized practices of citizen science. Particular attention was given to the management of data and the inclusion of ethical considerations. The focal point of the project was the process of radon building diagnosis which is supposed to be carried out whenever (high) radon concentrations are measured and should be prerequisite to mitigation works. As experience shows, however, this diagnosis is hardly implemented in France. To help remedy this situation, the pilot project recruited citizens already aware about radon from Pays Vesoul Val-de-Saône (East of France) to test an existing online self-evaluation guide for radon diagnosis, report on their operational experience and meet with radon/building experts. This enabled citizens to contribute to improvements in form and content to the guide and to ensure that it would be better fit for purpose. Comparison of the guide with experts’ practices offered additional perspectives on what building diagnosis should entail. The pilot project produced rich and high-quality data that will nurture the evolution of the guide. The project demonstrated both the viability and the utility of applying the citizen science approach to radon post-measurement phases, with measurable benefits in bridging knowledge gaps and in encouraging behavioural changes. The results of using a citizen science approach in the field of radon management and research are encouraging, and they far outweigh the challenges involved in the implementation.

Some Problems of Ultra-High-Speed Transportation Technologies

Purpose. The main purpose of the work is to identify some technical problems of high-speed transport that limit the effectiveness of relevant transport technologies in order to solve problems in the future and achieve progress in this area. Methodology. The theoretical analysis of scientific and technical publications, system analysis, numerical calculations, and exploratory forecasting were used. The features of the operation of high-speed transport of the 5th and 6th generation, based on the electrodynamic (electromagnetic) principle of movement and capable of reaching speeds from 200 to 60,000 km/s, are considered. Findings. The authors have established: 1) Maglev trains can become widespread in developed countries for passenger transportation and reach speeds of 600–700 km/h. They will be even cheaper, more comfortable and attractive due to new advances in high-temperature superconductivity, the use of nanoelectronics-based devices, and the solution of the issue of magnetic protection of passengers; 2) several Hyperloop lines are expected to be built for freight transportation. As operational experience is gained and safety issues of traveling in a vacuum pipeline are resolved, passenger lines may be launched. The Hyperloop will be able to reach speeds of up to 1,200 km/h; 3) Railgun transportation efficiency is expected to increase if new materials are developed and applied that would reduce ablation in extreme operating conditions. The Railgun will continue to be used in the scientific and technical sphere and in space technology; 4) it is possible to create an experimental Space Tram or its improved version if it is possible to develop the latest materials that can withstand ablation at high currents and speeds, and if there is a breakthrough in the field of high-temperature superconductivity. This development promises to significantly speed up the launch of payloads into orbit; 5) Breakthrough Starshot is unlikely to be created due to a number of technical difficulties that are far from being resolved. Originality. For the first time, the authors conducted a comprehensive analysis of technical problems in the field of ultra-high-speed transport technologies based on the electrodynamic (electromagnetic) principle of movement and proposed a forecast for the development of this transport in the next 20–30 years. Practical value. Based on the results obtained, it is possible to successfully solve the identified technical problems, which will increase the efficiency of ultra-high-speed transport technologies based on the electrodynamic (electromagnetic) principle of acceleration, movement and braking. In the near future, this will serve to speed up the introduction of freight transportation by Hyperloop-type transport and improve the acceleration devices for macrobodies such as Railgun.

Application of risk-based approach in switching operations preparation at Novovoronezh NPP

The article discusses one of the problematic issues of operating nuclear power plants - revenue losses caused by staff mistakes. Existing methods and approaches to reducing the number of such incidents are analyzed. Despite the efforts made, the problem remains relevant. One of the directions for reducing the number of equipment failures is the study and use of internal and external operational experience. A description is given of a system for preventing the recurrence of negative operating experience, developed at the Novovoronezh Nuclear Power Plant, which is used in preparation for switching equipment. The system is an information base, the information in which is structured by types of equipment used at the Novovoronezh Nuclear Power Plant, allowing only the information directly related to the upcoming switches to be communicated to the operational staff. Suggestions for its further improvement, taking into account the recommendations of the International Atomic Energy Agency, are considered. A forecast is given for the dynamics of reducing the number of violations after the introduction of this system into industrial operation.​

Features of applying safeguards to Optimized Floating Power Unit spent nuclear fuel handling

After the Floating Power Unit Akademik Lomonosov with the KLT-40S reactor plant had been successfully commissioned, the next step for ROSATOM was to develop optimized floating power units (OFPU). OFPUs powered by the RITM reactor plant are an export-oriented product, and they designed to operate on sites outside Russia. OFPU engineering solutions are based upon the practical design and operation experience in nuclear-powered icebreakers and upon problem solving to assure safety for operation of nuclear plants under severe northern conditions. At the nuclear fuel enrichment lower than 20%, the refueling interval for the OFPU may be up to 10 years depending on Loadings. The RITM reactor refueling process has a number of differences compared to the refueling process of other nuclear power plants fitted with water-cooled water-moderated power reactors. RITM plants have never been placed under the IAEA Safeguards, and capabilities and features of applying the IAEA Safeguards to such plants require an additional analysis. The developed operation model assumes that the OFPU be operated on a deployment site for a long period, and all fuel handling operations will be done at a specialized facility in the Russian Federation (RF). This paper is discussing the major fuel handling features in the life cycle of the OFPU fitted with RITM-200M—these are the critical features in terms of the IAEA Safeguards. Also, the paper is providing the designers’ perspective on solving the key non-proliferation problems through adapting the Safeguards approaches with account of the OFPU technical features.

Operationalising targeted next-generation sequencing for routine diagnosis of drug-resistant TB.

Phenotypic drug susceptibility testing (pDST) for Mycobacterium tuberculosis can take up to 8 weeks, while conventional molecular tests identify a limited set of resistance mutations. Targeted next-generation sequencing (tNGS) offers rapid results for predicting comprehensive drug resistance, and this study sought to explore its operational feasibility within a public health laboratory in Mumbai, India. Pulmonary samples from consenting patients testing Xpert MTB-positive were tested for drug resistance by conventional methods and using tNGS. Laboratory operational and logistical implementation experiences from study team members are shared below. Of the total number of patients tested, 70% (113/161) had no history of previous TB or treatment; however, 88.2% (n = 142) had rifampicin-resistant/multidrug-resistant TB (RR/MDR-TB). There was a high concordance between resistance predictions of tNGS and pDST for most drugs, with tNGS more accurately identifying resistance overall. tNGS was integrated and adapted into the laboratory workflow; however, batching samples caused significantly longer result turnaround time, fastest at 24 days. Manual DNA extraction caused inefficiencies; thus protocol optimisations were performed. Technical expertise was required for analysis of uncharacterised mutations and interpretation of report templates. tNGS cost per sample was US$230, while for pDST this was US$119. Implementation of tNGS is feasible in reference laboratories. It can rapidly identify drug resistance and should be considered as a potential alternative to pDST.

Development of a New Model for the Formation of Wax Deposits through the Passage of Crude Oil within the Well

Wax deposits related to flow assurance are a costly problem in oil production in many fields around the world. Modeling of this process is the main tool for creating and optimizing methods to deal with this problem. This paper considers a new empirical model for the formation of these deposits, based on the results of an array of laboratory studies, theoretical data and technological calculations are presented. The created technique takes into account the conditions of oil flow, data from laboratory studies, and the water cut of the product. The experience of the industrial operation of the technique showed a high convergence of the calculated and actual deposit profiles. Based on a comparison of the calculated and actual deposit profiles, it was concluded that the standard deviation of maximum wax thickness is 6.0%, and the depth with the greatest wax thickness is 3.5%, which is a fairly high result. The use of this technique makes it possible to optimize the depth of mechanical cleaning of the well, the installation of heating cables, as well as the parameters of hot flushing, which increases their efficiency and reduces the cost of combating the formation of wax deposition.

Experimental and numerical evacuation study in tall office building

The duration of the evacuation process in case of emergencies in tall buildings is a crucial issue. Various factors have significant impact on the evacuation time, e.g. stairwell geometry, speed, density, pre-evacuation delay, number of occupants and their familiarity with the building, behavior, age, gender, physical abilities, relationships between people, etc. Although there are many studies on the subject, research results from Bulgaria and comparison with those from other places in the world are not yet available. Also, studies performed by researchers who have professional operational firefighting experience are very limited. In this study, two evacuation experiments in a new 107 m tall office building in Bulgaria were designed under the supervision of professional firefighting personnel. The first experiment was conducted to estimate the free movement characteristics under “normal” conditions for determining the average duration of the evacuation and the range of the vertical speed. Thirteen participants were instructed to move down from 17F to outside the building, following their normal habits. Their evacuation times differed in the range from 192 s–328 s, while the vertical speed is highest at the upper floors 0.35 m/s and reduce to 0.20 m/s just before the exits. The second experiment was an evacuation drill of 177 people from the floors they work in the building. The evacuation duration of this experiment for all these people from the building was in the range of 2–6 min. The study is also enriched through Pathfinder software simulations for verification of the results, where a good match was observed (6:26 min total evacuation time). Another simulation at the maximum occupants’ capacity of the building with 2195 people was also run (24:48 min for the total evacuation time). We believe that the benefits achieved on the differences in the real experimental data from different parts of the world can be valuable for validation of tall building evacuation models. In addition, the link between the evacuation drill findings and the professional firefighting considerations, problems and decision-making operations in case of fire is discussed.

Stabilizing the Operation Modes of a Modern Multi-Machine Power System after Large Disturbances

Operational experience has shown that the tuning of stabilization channels of automatic excitation controllers (AEC) adopted in the UES of Russia improves steady-state stability in the power system both for long power lines and through weak connections, as well as in the event of small fluctuations in parameters. However, situations may occur in a multi-machine power system during transients after large disturbances and loss of synchronism between generators with large power fluctuations when the adopted (standard) tuning does not provide rapid suppression of these fluctuations. In an emergency situation, a prolonged transient with large power fluctuations can cause a local damage to evolve into a system accident. The article describes a method for stabilizing the operation modes in a multi-machine power system, according to which it is proposed to produce stabilizing AEC signals based on the difference of deviations between the shaft rotation frequency of each unit and the voltage frequency on the power plant busbars. Such signals will contribute to fast synchronization of generators with respect to one another and prevent power overflows between them during oscillations. In addition, with the stabilizing signals formed in this way, there will be no need for repeatedly retuning the AEC in the course of power system development and as changes are made in the electrical network structure; moreover, a widespread introduction of the proposed approach will significantly reduce the risk of torsional vibration of the turbine unit shaft. The results of the discussion of the proposed stabilization method by the UES Scientific and Technical Council are presented.