Miracle-dz/UniFAR-FTUs huggingface dataset:
Thermoacoustic instability in a solid rocket motor: non-normality and nonlinear instabilities

An analytical framework is developed to understand and predict the thermoacoustic instability in solid rocket motors, taking into account the non-orthogonality of the eigenmodes of the unsteady coupled system. The coupled system comprises the dynamics of the acoustic field and the propellant burn rate. In general, thermoacoustic systems are non-normal leading to non-orthogonality of the eigenmodes. For such systems, the classical linear stability predicted from the eigenvalue analysis is valid in the asymptotic (large time) limit. However, the short-term dynamics can be completely different and a generalized stability theory is needed to predict the linear stability for all times. Non-normal systems show an initial transient growth for suitable initial perturbations even when the system is stable according to the classical linear stability theory. The terms contributing to the non-normality in the acoustic field and unsteady burn rate equations are identified. These terms, which were neglected in the earlier analyses, are incorporated in this analysis. Furthermore, the short-term dynamics are analysed using a system of differential equations that couples the acoustic field and the burn rate, rather than using ad hoc response functions which were used in earlier analyses. In this paper, a solid rocket motor with homogeneous propellant grain has been analysed. Modelling the evolution of the unsteady burn rate using a differential equation increases the degrees of freedom of the thermoacoustic system. Hence, a new generalized disturbance energy is defined which measures the growth and decay of the oscillations. This disturbance energy includes both acoustic energy and unsteady energy in the propellant and is used to quantify the transient growth in the system. Nonlinearities in the system are incorporated by including second-order acoustics and a physics-based nonlinear unsteady burn rate model. Nonlinear instabilities are analysed with special attention given to ‘pulsed instability’. Pulsed instability is shown to occur with pressure coupling for burn rate response. Transient growth is shown to play an important role in pulsed instability.
A risk based approach for trading renewable electricity

Growing energy demand and climate change due to increasing CO2 emissions are two major global issues. The development of Supergrids, which involves connecting national energy supply grids together via interconnections, has been proposed as a measure to overcome these challenges. Supergrids arguably aid the implementation of other measures such as managing demand and development of renewable sources of energy, whilst it has its own benefits, perhaps, the most important one being its economic efficiency in comparison with generating electricity. A key challenge for developing Supergrids is finding the most suitable countries with which to make an interconnection. This doctoral research aims to develop a risk-based theoretical framework for selecting the most appropriate country (ies) with which to make grid interconnections and trade renewable electricity. Quantitative risk analysis technique is used to compare candidate countries by taking into the account the various risks associated with the construction and maintenance of interconnections. The risks include: social, technical, economic, environment and political aspects. The framework is demonstrated using the UK as a case study.
Flow field analysis for double stream nozzle: application to jet noise

The present paper deals with jet flow and noise comparisons between experimental data and numerical simulation results. ONERA took part of EU CoJeN (Coaxial Jet Noise) project which permitted to acquire a large experimental database at the end of the project. Firstly, a summary of experimental and numerical results is presented together with a complete list of available data. Experimental set-up and methods are briefly recalled; then, a synthesis of data is made in view of comparisons. Finally, comparisons between experimental and numerical results are presented. The comparisons are based on mean values, two-point velocity correlations and near field pressure levels and spectra. The objectives of these comparisons are to qualify the simulation and to understand physical phenomena in coaxial jet. This work permitted to document the discrepancies observed in the LES simulations. In particular it is shown that a higher level of turbulence a few diameters downstream of the nozzle exit maybe responsible for an over-estimation of far-field noise levels. This overpredicted energy transfer to turbulent flow is also responsible of a too short potential core. Although the overall content of the simulation seems satisfactory, except the exaggerated turbulence growth, it is proposed to improve the numerical simulations by somewhat reducing the grid coarsening in the first diameters downstream of the nozzle exit. This should permit to improve noise prediction of jet flows.
Benchmark for evaluation and validation of reactor simulations (BEAVRS)

Advances in parallel computing have made possible the development of high-fidelity tools for the design and analysis of nuclear reactor cores, and such tools require extensive verification and validation. This paper introduces BEAVRS, a new multi-cycle full-core Pressurized Water Reactor (PWR) depletion benchmark based on two operational cycles of a commercial nuclear power plant that provides a detailed description of fuel assemblies, burnable absorbers, in-core fission detectors, core loading patterns, and numerous in-vessel components. This benchmark enables analysts to develop extremely detailed reactor core models that can be used for testing and validation of coupled neutron transport, thermal-hydraulics, and fuel isotopic depletion. The benchmark also provides measured reactor data for Hot Zero Power (HZP) physics tests, boron letdown curves, and three-dimensional in-core flux maps from fifty-eight instrumented assemblies. Initial comparisons between calculations performed with MIT's OpenMC Monte Carlo neutron transport code and measured cycle 1 HZP test data are presented, and these results display an average deviation of approximately 100 pcm for the various critical configurations and control rod worth measurements. Computed HZP radial fission detector flux maps also agree reasonably well with the available measured data. All results indicate that this benchmark will be extremely useful in validation ofmore » coupled-physics codes and uncertainty quantification of in-core physics computational predictions. The detailed BEAVRS specification and its associated data package is hosted online at the MIT Computational Reactor Physics Group web site (http://crpg.mit.edu/), where future revisions and refinements to the benchmark specification will be made publicly available. (authors)« less
Anti-termite Performance of Japanese and Foreign Timber Species under Different Degradation Environments

日本産および外国産の15樹種の心材を用い，ヤマトシロアリおよびイエシロアリを対象とした室内試験により耐蟻性を評価した。 さらに，各樹種試験体を全国9カ所の野外に非接地・非暴露状態で設置し，加害シロアリ種および気象条件と食害指数との関係を検討した。 室内試験の結果，イエシロアリ，ヤマトシロアリに対して，耐候操作を経ないレッドウッド，スギ，カリーが，耐蟻性の指標に設定した耐蟻インデックス値80％を下回った。 一方，耐候操作により，ヤマトシロアリではヒバ，レッドウッド，スギで耐蟻インデックス値が顕著に減少したのに対して，イエシロアリでは耐候操作前後における耐蟻性の相違は，ヤマトシロアリの場合ほど顕著には認められなかった。 野外試験では，高比重の広葉樹材の中ではカリーが高い食害指数を示し，耐蟻性が低いと評価された。 また試験地の違いによって，同期間の暴露であっても，供試樹種の食害指数が異なることが明らかとなった。
Numerical Modeling of Seismic Soil-Structure Interaction for the Cut-and-Cover Structure BART Warm Spring Extension

This paper presents the technical approach and the results of site response and seismic soil-structure interaction (SSI) analyses performed to develop free-field and SSI racking deformation that the reinforced concrete box structure subway will experience during the design seismic event. The study compared results computed from different computer programs (SHAKE, FLUSH, and FLAC) using equivalent linear and nonlinear soil models. In addition, the effects of soil stratigraphy and the construction methods are evaluated and presented in this paper. Results of the analyses were compiled as racking curves to be used for final design of the reinforced concrete box structure.
Transfer of resistance alleles from herbicide-resistant to susceptible grass weeds via pollen-mediated gene flow

Abstract The objective of this paper was to review the reproductive biology, herbicide-resistant (HR) biotypes, pollen-mediated gene flow (PMGF), and potential for transfer of alleles from HR to herbicide-susceptible grass weeds including barnyardgrass, creeping bentgrass, Italian ryegrass, johnsongrass, rigid (annual) ryegrass, and wild oats. The widespread occurrence of HR grass weeds is at least partly due to PMGF, particularly in obligate outcrossing species such as rigid ryegrass. Creeping bentgrass, a wind-pollinated turfgrass species, can efficiently disseminate herbicide resistance alleles via PMGF and movement of seeds and stolons. The genus Agrostis contains about 200 species, many of which are sexually compatible and produce naturally occurring hybrids and hybrids with species in the genus Polypogon. The self-incompatibility, extremely high outcrossing rate, and wind pollination in Italian ryegrass clearly point to PMGF as a major mechanism by which herbicide resistance alleles can spread across agricultural landscapes, resulting in abundant genetic variation within populations and low genetic differentiation among populations. Italian ryegrass can readily hybridize with perennial ryegrass and rigid ryegrass due to their similarity in chromosome numbers (2n = 14), resulting in interspecific gene exchange. Johnsongrass, barnyardgrass, and wild oats are self-pollinated species, so the potential for PMGF is relatively low and limited to short distances; however, seeds can easily shatter upon maturity before crop harvest, leading to wider dispersal. The occurrence of PMGF in reviewed grass weed species, even at a low rate, is greater than that of spontaneous mutations conferring herbicide resistance in weeds and thus can contribute to the spread of herbicide resistance alleles. This review indicates that the transfer of herbicide resistance alleles occurs under field conditions at varying levels depending on the grass weed species. Nomenclature: Barnyardgrass; Echinochloa crus-galli (L.) Beauv. ; creeping bentgrass; Agrostis stolonifera L. ; Italian ryegrass; Lolium perenne ssp. multiflorum (Lam.) Husnot; johnsongrass; Sorghum halepense (L.) Pers. ; perennial ryegrass; Lolium perenne L. ; rigid (annual) ryegrass; Lolium rigidum Geud. ; sterile oat; Avena sterilis L. ; wild oat; Avena fatua L.
Sediment Transport Dynamism in the Confluence Area of Two Rivers Transporting Mainly Suspended Sediment Based on Sentinel-2 Satellite Images

Downstream of the confluence of rivers, complex hydrological and morphological processes control the flow and sediment transport. This study aimed to analyze the spatio-temporal dynamics of suspended sediment in the confluence area of the Tisza and its main tributary Maros River using Sentinel-2 images and to reveal the correlation between the hydrological parameters and the mixing process through a relatively long period (2015–2021). The surficial suspended sediment dynamism was analyzed by applying K-means unsupervised classification algorithm on 143 images. The percentages of the Tisza (TW) and Maros (MW) waters and their mixture (MIX) were calculated and compared with the hydrological parameters in both rivers. The main results revealed that the areal, lateral, and longitudinal extensions of TW and MIX have a better correlation with the hydrological parameters than the MW. The Pearson correlation matrix revealed that the discharge ratio between the rivers controls the mixing process significantly. Altogether, 11 mixing patterns were identified in the confluence area throughout the studied period. The TW usually dominates the confluence in November and January, MW in June and July, and MIX in August and September. Predictive equations for the areal distribution of the three classes were derived to support future water sampling in the confluence area.
Comparison of academic stress between government and private school higher secondary students

Background: Academic stress is the feeling of anxiety or apprehension on the academic activities. It can leads to negative impact on learning capacity, academic performance, education and employment attainment. Objective: The objective of the study was to assess and compare the level of academic stress between the government and private school higher secondary school students. Methods: Non-experimental cross sectional research design was adopted with 100 participants who selected by cluster sampling technique at selected schools. The tool used for the study was demographic variables and perceived stress scale to assess the level of stress. Results: Out of 50 participants from government school, 14(28%) had low level of stress, 23 (46%) had moderate level and 13 (26%) had high level of stress whereas in out of 50 private school students four (8%) had low level of stress, 19(38%) had moderate level and 17(54%) had high level of stress. Conclusion: The study findings concluded that there is high level of stress found among students studying in both the schools and high percentage was observed in private school students. Periodical student counseling including career guidance, stress management strategies can be incorporated in the curriculum to cope up with stressful events.
The acoustic characteristics of the Çarşı Mosque in Trabzon, Turkey

This study aimed to investigate the objective parameters of sound in relation to the types of materials on wall surfaces and the density of people attending the main prayer hall of the Çarşı Mosque that was built in 19th century in the city of Trabzon (Turkey). The numerical values of objective parameters of sound in the prayer hall were simulated using Odeon version 10 computer software. The prayer hall was modelled for two different scenarios. In the first scenario, the materials on all surfaces of the prayer hall were assigned as in their current state. In the second scenario, wood was used as the simulation material on the surfaces of the side wall and rear wall facing qiblahh. In addition, the numerical values of the objective parameters of sound were estimated for three different scenarios: a full, semi-full and empty prayer hall. The results showed that the fullness of the prayer hall in the mosque and types of materials on surfaces could affect the objective parameter values of sound especially at low frequencies. The finding of this study would provide useful objective parameters of sound for different types of materials for construction of wall and ceiling surfaces of prayer halls in mosques.
A RESEARCH STUDY ON EDUCATION EFFECT ON FAMILY PLANNING AMONG MARRIED COUPLES

: Introduction: Family size is an important population, socio-economic and reproductive health issue. Number of children preferred in a society generally influences the population of society and population growth rate. Education of both the parents play a significant role in determining the family size. The study aims towards finding the effect of education of parents on the family size, so that using local data, attention can be drawn on this major demographic determinant to improve the quality of life of people. The study was conducted in Khyber Teaching Hospital MTI Peshawar. The duration of our study was from July 2020 to August 2020.Our sample was of 100 married couples. Methodology: After taking informed consent from the respondents, data was collected through a preformed questionnaire having two separate sections. Section 1 included the demographic details of the respondents while section 2 was based on a total of 14 close ended questions regarding the number of children, educational status, family values and their personal awareness about contraceptives and education. Results: According to our research study conducted on a 100 people, in which age distribution of male respondents showed that 29% of them are in the age of 40-49 years (period of reproductive potential). 63% of them were qualified up to graduate and post-graduate level. Age distribution of female respondents showed that most of them were between ages of 30-39 years (period of high reproductive potential). 66% of them were qualified up to graduate and post graduate level. Chi-square valued showed that association between the education level of parents and number of children with the p-value of <0.001 for males and <0.005 for females.63% of highly educated families have less children while less educated have more children showing a negative relation between parent education and family size. Conclusions: Level of education has direct relationship with the use of contraceptives and inverse relationship with the number of children. Education process helps parents by raising awareness and decision making about the use of contraceptives and ultimately family size.
Numerical Simulation of Thermofluid Characteristics of Two-Phase Slug Flow in Microchannels

A fundamental study of heat transfer characteristics of two-phase slug flow in microchannels is carried out employing the Volume-of-Fluid (VOF) method. Despite of the fact that numerical simulations of two-phase flows in microchannels have been attempted by many investigators, most efforts seem to have failed in correctly capturing the flow physics, especially those pertaining to the slug flow regime characteristics. The presence of a thin liquid film in the order of 10 μm around the bubble is a contributing factor to the above difficulty. Typically, liquid films have a significant effect on the flow field and heat transfer characteristics. In the simulations reported in this paper, the film is successfully captured and a very high local convective heat transfer coefficient is observed in the film region. A strong coupling between the conductive heat transfer in the solid wall and the convective heat transfer in the flow field is observed and characterized. Results showed that unsteady heat transfer through the solid wall in the axial direction is comparable to that in the radial direction. Results also showed that a fully developed condition could be achieved fairly quickly compared to single-phase flows. The fully developed condition is defined based on the Peclet number (Pe) and a dimensionless length of the liquid slug. Local and time-averaged Nusselt numbers for slug flows are reported for the first time. It was found that significant improvements in the heat transfer coefficient could be achieved by short slugs where the Nu number was found to be 610% higher than in single-phase flows. The study revealed new findings related to slug flow heat transfer in microchannels with constant wall heat flux. © 2010 ASME
Adversarial Design

In Adversarial Design, Carl DiSalvo examines the ways that technology design can provoke and engage the political. He describes a practice, which he terms "adversarial design," that uses the means and forms of design to challenge beliefs, values, and what is taken to be fact. It is not simply applying design to politics--attempting to improve governance, for example, by redesigning ballots and polling places; it is implicitly contestational and strives to question conventional approaches to political issues. DiSalvo explores the political qualities and potentials of design by examining a series of projects that span design and art, engineering and computer science, agitprop and consumer products. He views these projects-- which include computational visualizations of networks of power and influence, therapy robots that shape sociability, and everyday objects embedded with microchips that enable users to circumvent surveillance--through the lens of agonism, a political theory that emphasizes contention as foundational to democracy. Each of these projects engages one of three categories as a medium--information, robots, and ubiquitous computing--and in each of them certain distinctive qualities of computation are used for political ends or to bring forth political issues. DiSalvo's illuminating analysis aims to provide design criticism with a new approach for thinking about the relationship between forms of political expression, computation as a medium, and the processes and products of design.
The effect of parenting styles on children’s risk perception on roads

Although there is evidence of a significant impact of the family on children's safety and risky behaviors, few studies have examined this issue in detail. Children under the age of 10, although they rarely participate in traffic completely independently, are a vulnerable population from a traffic safety perspective. In addition to the number of children who die in incidents, some of them suffer from lifelong disabilities. Besides various educational methods and making safe school zones, there is a need to pay attention to the impact of parents on children's understanding of traffic safety. In this study, the effect of parent on children's perception of safety and danger on roads is investigated. For this purpose, through an interview, children aged 6-9 years were asked to identify 11 unsafe traffic behaviors. Parenting styles and demographic information were collected from their parents through a questionnaire. The results showed that children's risk perception is related to age, gender, and socio-economic status. In addition, children's ability to perceive risk is associated with negative parenting styles (corporal punishment and poor monitoring). The results of this study highlight the effects of parents' education on children's awareness of road safety. The importance of parenting styles and other factors affecting children's understanding of traffic risks should be informed to families. It is also important to establish the necessary infrastructure to increase children's safety by promoting parenting skills through beneficial policies and holding training workshops for parents.
The pre-foundation evolution of proactiveness in born global and non-born global USOs

ABSTRACT This article adds to existing work on the drivers of early internationalization by exploring how born globals’ proactiveness evolves during their pre-foundation period and influences their internationalization timing post-foundation. We perform a comparative, qualitative field study of born globals and non-born globals based on 22 university spin-out companies. The findings reveal that proactiveness during pre-foundation, which emerged as an evolutionary nonlinear process in both categories of firms, was critical in facilitating or inhibiting early internationalization. It emerged that born globals behaved reactively during the earliest phases of pre-foundation, and gradually became more proactive as the firm approached formal foundation. Conversely, non-born globals first behaved proactively and, as the firm moved toward formal foundation, became more reactive. The findings bear important theoretical implications for international entrepreneurship, as well as for literature on university spin-outs and new venture behavior, by generating new context-specific, processual evidence on the role of pre-foundation proactiveness as an antecedent of USO early internationalization.