Research on the rapid combustion process of butane under microwave discharge

To study the combustion process of fuel in the microwave plasma torch, we designed a butane microwave plasma device exploiting a tungsten rod as an electrode. Through analysis of the image record by high-speed camera, we found that the discharge of butane microwave plasma torch is a cyclic process at atmospheric pressure at a frequency of around 100 Hz. During the discharge, the active particles continuously diffuse from the electrode to the outside like the bloom of the flower. Then, the variation of plasma torch of jet height and temperature with microwave power is obtained. In addition, we studied the effects of different butane flow rates on the plasma torch. The results illustrate that excessive butane will lead to carbon deposition on the electrode. All in all, this work provides a new understanding of the combustion of the microwave plasma torch, which is conducive to the further development of microwave plasma in the fields of waste gas treatment, fuel combustion, and plasma engine.

Dislocation re-emission induced staged work hardening in graphene-nanotwin reinforced Cu: A molecular dynamics simulation study

Graphene and nanotwins are two effective reinforced microstructural features to achieve improved mechanical properties of metallic composites, while the two features are generally applied separately. In this study, graphene/nano-twinned Cu nanocomposites models with different arrangement of the graphene and twin boundaries were designed by using molecular dynamics (MD) simulations, and the dislocation processes and the interactions between dislocation and graphene/twin were simulated and investigated. The simulation results indicated the arrangement of graphene and nanotwin affects the work hardening behaviors in the graphene/nano-twinned Cu composites, i.e., two staged work hardening behavior corresponded to cyclic process of dislocation hindrance-absorption-reemission in the model with relatively small twin spacing and twin-graphene spacing, while the work hardening dominated by dislocation intersection and multiplication occurred in the model with large twin-spacing. The simulation provided herein demonstrated that the special arrangement of graphene and nanotwins led a way to tailoring the mechanical properties of metallic composites with various work hardening behaviors. Graphical abstract Highlights 1. Dislocation reactions between twins and graphene were simulated and analyzed. 2. Twin-graphene distance and the twin distance play key roles in the reaction. 3. The mechanism corresponding to work hardening changes in the limited two distances.

Investigation of Changes to Triaxial Shear Strength Parameters and Microstructure of Yili Loess with Drying–Wetting Cycles

This research examined the drying–wetting cycles induced changes in undrained triaxial shear strength parameters and microstructural changes of Yili loess. The drying–wetting cycles were selected as 0, 1, 3, 5, 10, 20 and 30. Then, we collected Yili loess samples and performed unconsolidated-undrained (U-U) triaxial shearing tests to ascertain the variation in shear strength parameters with drying–wetting cycles. Additionally, we investigated the microstructural changes of Yili loess samples under drying–wetting cycles simultaneously via nuclear magnetic resonance (NMR) and scanning electron electroscopy (SEM). Finally, we established a grey correlation model between shear strength and microstructural parameters. Under U-U conditions, the prime finding was that the loess’s shear strength parameters changed overall after drying–wetting cycles; in particular, the internal friction angle φ dropped significantly while the cohesion c changed only slightly during cycles. For all the cycles, the first cycle gave the highest change. Soil morphology deterioration was evident at the initial stage of cycles. During the entire drying–wetting cyclic process, pore size distribution showed progressive variance from two-peak to a single-peak pattern, while both porosity and the fractal dimension of pores increased gradually towards stability. Soil particle morphology became slowly simple and reached the equilibrium state after 20 drying–wetting cycles. Under cyclic drying–wetting stress, the shear strength parameter changes were significantly correlated to microstructural modifications. This investigation was related to loess in the westerly region. The findings were expected to provide new insight into establishment of the connection between microstructure and macro stress–strain state of loess. To some extent, it provided a theoretical basis for the prevention and control of loess engineering geological disasters in Yili, Xinjiang and other areas with similar climate and soil types.

STATE OF BOTTOM SEDIMENTS OF THE VORONEZH RESERVOIR IN THE PLACES OF WATER DISCHARGE FROM THE TREATMENT FACILITIES OF THE CITY OF VORONEZH

Рассмотрена проблема загрязнения Воронежского водохранилища в пределах Воронежской городской агломерации, в местах сброса вод с очистных сооружений предприятий левого берега. В работе использованы результаты количественного химического анализа донных отложений, выполненных на базе эколого-аналитической лаборатории факультета географии, геоэкологии и туризма Воронежского госуниверситета, а также данные мониторинга, предоставленных Федеральной службой по надзору в сфере природопользования и Департаментом природных ресурсов и экологии Воронежской области. База данных включает результаты наблюдений с 2000 по 2021 год. По составу осадков прослежена история аккумуляции загрязнителей, выделены проблемные зоны водоема в каждом исследуемом периоде. Выполнен пространственно-временной анализ содержаний загрязняющих веществ, рассчитаны «кларки концентрации» тяжелых металлов, по которым для каждой точки наблюдения в порядке возрастания значения признака построен ранжированный ряд. На основании лабораторных исследований и результатов их статистической обработки с применением корреляционного анализа сделаны выводы о перспективах существования и развития Воронежского водохранилища. Проверены корреляционные связи между «кларками концентрации» и суммой выпавших осадков за календарный и за гидрологический год. По содержаниям сероводорода в различные годы, сделаны выводы о диапазоне колебания концентраций и формировании цикличного процесса. Выделена зона устойчивой деградации водоема. Ее формирование происходит выше и ниже сброса с городских очистных сооружений левого берега города. Результаты многолетних наблюдений за качеством донных отложений указывают на значительную техногенную нагрузку со стороны Воронежской городской агломерации. Недостаточная очистка воды, медленная скорость течения и турбулентность природной воды ускоряет процесс естественного эвтрофирования водоема. The author considers the problem of pollution of the Voronezh water reservoir within the Voronezh urban agglomeration, in places of discharge of water from the treatment facilities of enterprises of the left bank. The paper uses the results of quantitative chemical analysis of bottom sediments performed on the basis of the ecological and analytical laboratory of the Faculty of Geography, Geoecology and Tourism of Voronezh State University, as well as monitoring data provided by the Federal Service for Supervision of Nature Management and the Department of Natural Resources and Ecology of the Voronezh Region. The database includes the results of monitoring from 2000 till 2021. On the basis of the composition of precipitation the author detected the history of accumulation of pollutants; as well she identified problem areas of the water reservoir in every study period. The author performed a spatio-temporal analysis of the contents of pollutants, calculated the "concentration clarkes" of heavy metals, according to which she created an ordered series for each observation point in ascending order of the attribute value. Based on laboratory studies and results of their statistical processing using correlation analysis the author draws some conclusions concerning the prospects for the Voronezh water reservoir existence and development. The correlations between the "concentration clarkes" and the amount of precipitation for the calendar and hydrological year have been verified. Based on the hydrogen sulfide content in different years, the author concludes about the range of concentration fluctuations and the formation of a cyclic process. She identified the zone of stable degradation of the water reservoir. Its formation occurs above and below the discharge from the municipal sewage treatment plants of the left bank of the city. The results of long-term observations of the quality of bottom sediments indicate a significant anthropogenic load on the part of the Voronezh urban agglomeration. Insufficient water purification, slow flow velocity and turbulence of natural water accelerate the process of natural eutrophication of the water reservoir.

The Influence of Long and Short Cycle Schemes of Self-Cycling Fermentation on the Growth of E. Coli and S. Cerevisiae

Self-cycling fermentation (SCF), a cyclic process in which cells divide once per cycle, has been shown to lead to improvements in productivity during bioconversion and, often, whole-culture synchronization. Previous studies have found that in some cases, the completion of synchronized cell replication occurred simultaneously with depletion of a limiting nutrient. However, exceptions were also observed when the end of cell doubling occurred before the exhaustion of the limiting nutrient. In order to better understand the underlying mechanisms and impacts of these growth patterns on bioprocessing, we investigated the growth of Escherichia coli and Saccharomyces cerevisiae in long- and short-cycle SCF strategies. Three characteristic events linked to SCF cycles were identified: (1) the completion of synchronized cell replication, (2) the depletion or a plateau of the limiting nutrient, and (3) characteristic points of control parameters (e.g., the minimum of dissolved oxygen and the maximum of carbon dioxide evolution rate). Three major trends stemming from this study and SCF literature were observed: (A) co-occurrence of the three key events in SCF cycles, (B) cycles for which cell replication ended prior to the co-occurrence of the other two events, and (C) cycles for which the time of depletion or a plateau of the limiting nutrient occurred later than the concurrence of the other two events. Based on these observations, a novel definition for SCF is proposed.

Enabling Continuous Commissioning through Building Management Systems

<p>The use and application of energy efficient technologies within new and existing buildings is a growing global trend. However, if they aren’t being commissioned, controlled and operated in an efficient way, are they really making a valid impact on the energy efficiency of our buildings? Building Management Systems (BMS) are installed within large scale non-residential buildings to control and govern the operation of Heating Ventilation and Air-Conditioning systems (HVAC). BMS monitor and process large amounts of data during their day-to-day operation, while the potential usefulness of BMS to implement energy optimising strategies is typically left un-utilised. There is a growing need to reduce building energy demand. Continuous Commissioning (CCx) may offer the potential to achieve this reduction through the ongoing or periodical assessment of building HVAC operation. As CCx is a cyclic process, and because BMS already monitor and process data in their day-to-day operations, they offer a potential, low overhead means of running CCx processes in buildings. This thesis reports a research project which explores this opportunity to assess and improve building operating efficiency by identifying what data and functional capabilities are required of a BMS to facilitate Continuous Commissioning. A systematic assessment of existing research and standards has highlighted a gap in industry knowledge on the specification of data required to implement CCx assessments to HVAC. There was also no definition of what BMS capabilities were important to the Continuous Commissioning process. These research gaps inspired five secondary research questions around which a mixed-method survey was developed and implemented to bridge the gap between BMS and CCx. The research methodology integrated a standard questionnaire and the Delphi method to explore user perceptions and develop a consensus of BMS requirements. Three survey rounds were distributed to New Zealand based industry experts. Each round informed the following round, with an element of feedback provided through the compilation of the previous round’s responses. This process enabled the industry experts to agree or disagree with the proposed consensus or provide an alternative insight to the questions asked. The results of the surveys were compiled to establish a definition of the top five CCx assessments applied to typical HVAC systems, data point trending requirements and BMS functions important to facilitating Continuous Commissioning. These findings were used to create a guideline for specifying BMS to facilitate Continuous Commissioning and create a soft landing for assessing HVAC during the operation phase of a building’s life. The outcome of this research bridges the gap between the specification of Building Management Systems and the requirements of the Continuous Commissioning process.</p>

Enabling Continuous Commissioning through Building Management Systems

<p>The use and application of energy efficient technologies within new and existing buildings is a growing global trend. However, if they aren’t being commissioned, controlled and operated in an efficient way, are they really making a valid impact on the energy efficiency of our buildings? Building Management Systems (BMS) are installed within large scale non-residential buildings to control and govern the operation of Heating Ventilation and Air-Conditioning systems (HVAC). BMS monitor and process large amounts of data during their day-to-day operation, while the potential usefulness of BMS to implement energy optimising strategies is typically left un-utilised. There is a growing need to reduce building energy demand. Continuous Commissioning (CCx) may offer the potential to achieve this reduction through the ongoing or periodical assessment of building HVAC operation. As CCx is a cyclic process, and because BMS already monitor and process data in their day-to-day operations, they offer a potential, low overhead means of running CCx processes in buildings. This thesis reports a research project which explores this opportunity to assess and improve building operating efficiency by identifying what data and functional capabilities are required of a BMS to facilitate Continuous Commissioning. A systematic assessment of existing research and standards has highlighted a gap in industry knowledge on the specification of data required to implement CCx assessments to HVAC. There was also no definition of what BMS capabilities were important to the Continuous Commissioning process. These research gaps inspired five secondary research questions around which a mixed-method survey was developed and implemented to bridge the gap between BMS and CCx. The research methodology integrated a standard questionnaire and the Delphi method to explore user perceptions and develop a consensus of BMS requirements. Three survey rounds were distributed to New Zealand based industry experts. Each round informed the following round, with an element of feedback provided through the compilation of the previous round’s responses. This process enabled the industry experts to agree or disagree with the proposed consensus or provide an alternative insight to the questions asked. The results of the surveys were compiled to establish a definition of the top five CCx assessments applied to typical HVAC systems, data point trending requirements and BMS functions important to facilitating Continuous Commissioning. These findings were used to create a guideline for specifying BMS to facilitate Continuous Commissioning and create a soft landing for assessing HVAC during the operation phase of a building’s life. The outcome of this research bridges the gap between the specification of Building Management Systems and the requirements of the Continuous Commissioning process.</p>

Family Caregiver Training During Medicare Home Health Care: Clinician Perspectives

During Medicare home health care, providers often rely on family caregivers to help meet patients’ care needs. Beginning in 2018, CMS requires home health agencies to provide training to family caregivers. This qualitative study is the first research to examine current patterns of family caregiver training, and related facilitators and barriers, during Medicare-funded home health care. We conducted semi-structured key informant interviews with home health nurses and physical therapists (n=19) from 4 diverse agencies, then performed thematic analysis of interview transcripts using a hybrid inductive and deductive coding approach. Clinicians described family caregiver education as a dynamic and cyclical process: simultaneously providing patient care, training family caregivers, and gathering additional information about patient needs and caregiver capabilities, then adjusting the care plan accordingly. We present a model of this cyclic process and describe its four major stages: Initial Assessment, Education, Reassessment, and Adjustment. Additionally, clinicians identified a range of structural, individual, and interpersonal factors which impact their ability to successfully train family caregivers. We define each factor and, using illustrative quotes from our interviews, elucidate its role as a facilitator and/or barrier to clinicians’ educational efforts. Findings provide the first model of caregiver training during home health care and highlight policy and practice changes to better support clinicians in these efforts; including greater visit flexibility, access to more experienced clinical mentors, and standardized caregiver assessment tools designed for this unique care setting.

Optimization of deep silicon etching process for microstructures fabrication

The paper presents the study of cyclic process of deep anisotropic silicon etching, called Oxi-Etch, in which the steps of etching and oxidation alternate, allowing deep etching of silicon with an anisotropic profile. This process forms typical for cyclic etching process sidewall profile called scalloping. Opportunities for modification and optimization of the process for specific application were investigated. The effects of optimization of the bias voltage and the duration of the etching step on the parameters of the resulting structures, such as the etching depth, wall roughness, and the accuracy of transferring the lithographic size, are considered. Balance between etch rate and scalloping was established.

Local Instructional Theory Topik Dua Tipe Kesalahan dalam Pengujian Hipotesis

Two types of errors are one of the important topics in hypothesis testing. Studying the two types of errors is not only studying how the procedure determines the probability of making an error, but it is very important to study the theoretical concepts of the two types of errors. To achieve this goal, a learning design is needed that can facilitate students to construct their own concepts of the two types of errors. The learning design developed is local instructional theory resulting from the cyclic process of hypothetical learning trajectory. The type of research used is design research using the model developed by Gravemeijer and Cobb. The test subjects used in this study were students of the Ma thematics Education Study Program, FMIPA UNP who took the Elementary Statistics Course in the July – December 2019 semester. This research resulted in a very practical local instructional theory used to facilitate students in carrying out horizontal and vertical mathematization processes, so that students are able to construct their own concepts of two types of errors in hypothesis testing.