scholarly journals Predicting the durability of ship's machine parts and mechanisms on the criterion of material fatigue

2020 ◽  
pp. 127-133
Author(s):  
В.К. Румб
Keyword(s):  
Fatigue Cracks ◽  
Experimental Studies ◽  
Fatigue Curve ◽  
Second Phase ◽  
Critical Dimensions ◽  
Material Fatigue ◽  
The Difference ◽  
Two Phases ◽  
The Moment

На основе теории о кристаллическом строении металлов рассмотрена физика усталостного разрушения. Показано, что зарождение и развитие усталостных трещин является случайным процессом, состоящим из двух фаз: первая – образование макроскопической (видимой) трещины; вторая – рост трещины до критических размеров, после которых наступает поломка детали. Приведены критерии работоспособности деталей по критерию усталости материала. Особое внимание уделено методическим положениям, позволяющим расчетным путем прогнозировать долговечность деталей для первой фазы усталости материала. Предлагаемая методика базируется на кривой усталости материала и корректированной гипотезе линейного суммирования повреждений. Отличительной особенностью методики является ее применимость для различных видов нагружения, в частности, показано как с ее помощью можно определять усталостную долговечность для режимного и блочного нагружений деталей. Отмечено, что для повышения точности прогнозирования долговечности необходимы дополнительные экспериментальные исследования прочности материала при циклическом нагружении, равном 1010 ÷ 1012циклов. В перспективе разработанная методика позволяет рассчитывать остаточную долговечность деталей как разность между расчетной долговечностью новой детали и ее наработкой до момента нового использования. Based on the theory about the crystalline structure of metals, the physics of fatigue destruction is considered. It is shown that the origin and development of fatigue cracks is a random process consisting of two phases: the first - the formation of a macroscopic (visible) crack; The second phase is the growth of the crack to critical dimensions, after which the part breaks. The criteria for the health of the parts are given on the criterion of material fatigue. Particular attention is paid to the methodical provisions, allowing the calculated way to predict the durability of parts for the first phase of material fatigue. The proposed technique is based on the material fatigue curve and the corrected hypothesis of linear summation of damage. A distinctive feature of the technique is its applicability for different types of loading, in particular, it shows how it can determine fatigue durability for the mode and block loading of parts. It is noted that additional experimental studies of the strength of the material in the cyclical load equal to 1010 ÷ 1012 cycles are needed to improve the accuracy of longevity prediction. In the long term, the developed technique allows to calculate the residual durability of parts as the difference between the calculated durability of the new part and its development until the moment of new use.

scholarly journals Biphasic pattern in the effect of severe measles infection; the difference between additive and multiplicative scale

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Nhat Thanh Hoang Le ◽  
Nhan Thi Ho ◽  
Bryan Grenfell ◽  
Stephen Baker ◽  
Ronald B. Geskus
Keyword(s):  
Infectious Diseases ◽  
Hospital Admission ◽  
Measles Virus ◽  
Hospital Admissions ◽  
Admission Rate ◽  
Second Phase ◽  
Before And After ◽  
The Difference ◽  
Two Phases ◽  
Additive Scale

Abstract Background Infection with measles virus (MeV) causes immunosuppression and increased susceptibility to other infectious diseases. Only few studies reported a duration of immunosuppression, with varying results. We investigated the effect of immunosuppression on the incidence of hospital admissions for infectious diseases in Vietnamese children. Methods We used retrospective data (2005 to 2015; N = 4419) from the two pediatric hospitals in Ho Chi Minh City, Vietnam. We compared the age-specific incidence of hospital admission for infectious diseases before and after hospitalization for measles. We fitted a Poisson regression model that included gender, current age, and time since measles to obtain a multiplicative effect measure. Estimates were transformed to the additive scale. Results We observed two phases in the incidence of hospital admission after measles. The first phase started with a fourfold increased rate of admissions during the first month after measles, dropping to a level quite comparable to children of the same age before measles. In the second phase, lasting until at least 6 years after measles, the admission rate decreased further, with values up to 20 times lower than in children of the same age before measles. However, on the additive scale the effect size in the second phase was much smaller than in the first phase. Conclusion The first phase highlights the public health benefits of measles vaccination by preventing measles and immune amnesia. The beneficial second phase is interesting, but its strength strongly depends on the scale. It suggests a complicated interaction between MeV infection and the host immunity.

scholarly journals Patterns of spatial methane distribution in the upper layers of permafrost in Central Yakutia

2017 ◽  
pp. 105-112
Author(s):  
M. Yu. Cherbunina ◽  
D. G. Shmelev ◽  
A. V. Brouchkov ◽  
V. S. Kazantsev ◽  
R. N. Argunov
Keyword(s):  
Field Studies ◽  
Methane Content ◽  
Central Yakutia ◽  
The Difference ◽  
The Moment ◽  
Methane Distribution ◽  
The Right ◽  
Ice Complex

The article presents the results of long-term field studies of methane in the upper part of permafrost for the different geomorphological levels of Central Yakutia. Patterns of spatial distribution of methane content across different landscapes were found. The highest concentrations of methane are found in alas deposits, the major role of methane in the conservation there goes to the moment of freezing the thermokarst lake draining. The difference in methane content in the sediments of the Late Pleistocene Ice Complex on the left and the right bank of the river Lena was identified. That is likely caused by the conditions of ice complex formation.

scholarly journals POPULATION SIZE AND SELECTION INTENSITY EFFECTS ON LONG-TERM SELECTION RESPONSE IN MICE

Genetics ◽  
1975 ◽  
Vol 79 (2) ◽  
pp. 305-323
Author(s):  
E J Eisen
Keyword(s):  
Inbreeding Depression ◽  
Genetic Correlations ◽  
Selection Response ◽  
Second Phase ◽  
Selection Intensity ◽  
Total Response ◽  
Family Selection ◽  
Effective Population ◽  
The Difference

ABSTRACT Long-term response to within full-sib family selection for increased postweaning gain was evaluated in lines having different effective population sizes (Ne) and selection intensities (i). Line designations were I4(4), I8(2), I16(2), M4(4), M8(2) and M16(2), where I and M indicate selection of the top 50% and 25%, respectively; 4, 8 and 16 represent the number of parental pairs per replicate and number of replicates is given in parentheses. Realized within full-sib family heritabilities (hR  2) in the first phase of selection (0-14 generations) were larger in 16-pair lines than in 4- and 8-pair lines. In the second phase of selection (>14 generations), hR  2 declined significantly (P<.01) in all lines, and only the I16 and M16 lines had hR  2 values significantly (P<.01) greater than zero. Realized genetic correlations involving number born, 12-day litter weight, weaning weight and six-week weight tended to decline in the second phase of selection. The I16, M16 and control (C16) replicates were crossed in all combinations at generation 14. Crosses were then selected within litters for high postweaning gain. The hR  2 values in the crossbred lines were all larger than those in the second selection phase for M16-1, M16-2 and I16-1, but not for I16-2. Within each Ne level, total response was significantly (P<.01) less for I lines compared with M lines. Total response increased as Ne increased, within each level of i. Relatively small differences in realized i values among Ne lines could not account for this result. The difference in total response among the Ne lines at a given selection intensity may be due to inbreeding depression and a combination of interactions involving "drift" and selection. By crossing replicates of the M lines with the C16 control, the effects of inbreeding depression were removed. Inbreeding depression and genetic drift, as defined herein, were equally important in accounting for differences among Ne lines in total response.

scholarly journals TWO PHASES IN THE DEVELOPMENT OF HEDWIG CONRAD-MARTIUS’ ONTOLOGICAL INVESTIGATION ON HUMAN BEING AND LIVING THINGS

2021 ◽  
Vol 10 (2) ◽  
pp. 398-424
Author(s):  
SIMONA BERTOLINI ◽  
Keyword(s):  
Structure Change ◽  
Second Phase ◽  
Human Being ◽  
Human Knowledge ◽  
Living Things ◽  
Ontological Categories ◽  
Biological Ontology ◽  
The Difference ◽  
Two Phases ◽  
Theoretical Results

Interest in the ontological constitution of living beings (with particular reference to the human being) characterizes the whole development of Hedwig Conrad-Martius’ philosophy. Several works written by the philosopher over the years deal with both the phenomenological description and the ontological foundation of the difference between plants, animals, and humans. Specifically, the ontological structure of the human being is investigated as a layered structure which presupposes those of plants and animals while overcoming them in a more complex and spiritual unity, on which human freedom and human knowledge depend. Although this topic maintains a crucial role in Conrad-Martius’ thought, the way the philosopher addresses it and the theoretical results of her phenomenological-ontological inquiry about it do not remain unchanged. Indeed, the ontological structure at the basis of phenomenal differences as well as the metaphysical foundations of this structure change over the decades. This paper aims at distinguishing between two phases, characterized by different ontological categories, through which Conrad-Martius’ anthropology and biological ontology develop. In the first phase, at the beginning of the twenties (precisely in her work Metaphysical Dialogues), the essential differences between plants, animals, and humans are explained with reference to a vital origin preceding the constitution of reality; to describe it Conrad-Martius employs terms such as “abyss” and “under-earthly realm.” In the second phase, exemplified by some writings published in the forties and the fifties, the reference to such a dimension disappears and the eidetic variety within the living world, including human specificity, is exclusively traced back to the finalistic substantiation of essences in the natural beings.

Differences of energy expenditure while sitting versus standing: A systematic review and meta-analysis

2018 ◽  
Vol 25 (5) ◽  
pp. 522-538 ◽  
Author(s):  
Farzane Saeidifard ◽  
Jose R Medina-Inojosa ◽  
Marta Supervia ◽  
Thomas P Olson ◽  
Virend K Somers ◽  
...  
Keyword(s):  
Systematic Review ◽  
Energy Expenditure ◽  
Energy Content ◽  
Meta Analysis ◽  
Experimental Studies ◽  
Final Analysis ◽  
Ovid Medline ◽  
The Difference ◽  
Mean Differences

Background Replacing sitting with standing is one of several recommendations to decrease sedentary time and increase the daily energy expenditure, but the difference in energy expenditure between standing versus sitting has been controversial. This systematic review and meta-analysis aimed to determine this difference. Designs and methods We searched Ovid MEDLINE, Ovid Embase Scopus, Web of Science and Google Scholar for observational and experimental studies that compared the energy expenditure of standing versus sitting. We calculated mean differences and 95% confidence intervals using a random effects model. We conducted different predefined subgroup analyses based on characteristics of participants and study design. Results We identified 658 studies and included 46 studies with 1184 participants for the final analysis. The mean difference in energy expenditure between sitting and standing was 0.15 kcal/min (95% confidence interval (CI) 0.12–0.17). The difference among women was 0.1 kcal/min (95% CI 0.0–0.21), and was 0.19 kcal/min (95% CI 0.05–0.33) in men. Observational studies had a lower difference in energy expenditure (0.11 kcal/min, 95% CI 0.08–0.14) compared to randomised trials (0.2 kcal/min, 95% CI 0.12–0.28). By substituting sitting with standing for 6 hours/day, a 65 kg person will expend an additional 54 kcal/day. Assuming no increase in energy intake, this difference in energy expenditure would be translated into the energy content of about 2.5 kg of body fat mass in 1 year. Conclusions The substitution of sitting with standing could be a potential solution for a sedentary lifestyle to prevent weight gain in the long term. Future studies should aim to assess the effectiveness and feasibility of this strategy.

Accuracy assessment of surgical planning and three-dimensional-printed patient-specific guides for orthopaedic osteotomies

2017 ◽  
Vol 231 (6) ◽  
pp. 499-508 ◽  
Author(s):  
Gwen Sys ◽  
Hannelore Eykens ◽  
Gerlinde Lenaerts ◽  
Felix Shumelinsky ◽  
Cedric Robbrecht ◽  
...  
Keyword(s):  
Accuracy Assessment ◽  
Average Distance ◽  
Three Dimensional ◽  
Patient Specific ◽  
Second Phase ◽  
Experimental Setup ◽  
Operative Planning ◽  
The Difference ◽  
Two Phases ◽  
Improved Accuracy

This study analyses the accuracy of three-dimensional pre-operative planning and patient-specific guides for orthopaedic osteotomies. To this end, patient-specific guides were compared to the classical freehand method in an experimental setup with saw bones in two phases. In the first phase, the effect of guide design and oscillating versus reciprocating saws was analysed. The difference between target and performed cuts was quantified by the average distance deviation and average angular deviations in the sagittal and coronal planes for the different osteotomies. The results indicated that for one model osteotomy, the use of guides resulted in a more accurate cut when compared to the freehand technique. Reciprocating saws and slot guides improved accuracy in all planes, while oscillating saws and open guides lead to larger deviations from the planned cut. In the second phase, the accuracy of transfer of the planning to the surgical field with slot guides and a reciprocating saw was assessed and compared to the classical planning and freehand cutting method. The pre-operative plan was transferred with high accuracy. Three-dimensional-printed patient-specific guides improve the accuracy of osteotomies and bony resections in an experimental setup compared to conventional freehand methods. The improved accuracy is related to (1) a detailed and qualitative pre-operative plan and (2) an accurate transfer of the planning to the operation room with patient-specific guides by an accurate guidance of the surgical tools to perform the desired cuts.

Audience development: a cross-national comparison

2017 ◽  
Vol 30 (2) ◽  
pp. 156-172 ◽  
Author(s):  
Macarena Cuenca-Amigo ◽  
Amaia Makua
Keyword(s):  
Qualitative Methodology ◽  
Second Phase ◽  
Content Type ◽  
Cultural Aspects ◽  
National Comparison ◽  
Two Phases ◽  
Audience Development ◽  
Definition Of ◽  
The Uk

Purpose The purpose of this paper is to review the concept of audience development, analysing differences between a number of countries and identifying common elements that underlie the concept regardless of the context. Design/methodology/approach In addition to the literature review, fieldwork has been conducted in the UK, Denmark, Italy, and Spain applying qualitative methodology. The study has been structured in two phases. The first phase comprised 26 in-depth interviews with European experts in audience development while the second phase consisted of six focus groups with European experts. Findings The paper reveals differences between countries, ranging from the definition of the term audience development to the approach undertaken. Despite this, a number of aspects, independent of the context and considered key to a successful audience development, are identified. These aspects are related to the consideration of the development of audiences as a transversal long-term strategy supported by the top management of the organisation. Originality/value The value provided is twofold. First, thanks to the empirical data used, the paper analyses the socio-cultural aspects that affect the emergence of country-specific approaches to audience development and it individuates general features and ideas that contribute to the better understanding of the concept itself. Second, it is one of the few academic works carried out in Spain on this issue.

scholarly journals Dynamic changes in anxiety level before and after reading and watching different types of online articles and videos respectively: A Pilot Study

2021 ◽  
Author(s):  
Sizhe Zhou ◽  
Keying Liu
Keyword(s):  
High School Students ◽  
Dynamic Effect ◽  
Anxiety Level ◽  
Second Phase ◽  
School Students ◽  
Before And After ◽  
Anxiety Levels ◽  
Two Phases ◽  
Ecological Momentary

In recent years, researchers studying anxiety in high school students have determined that therapeutic videos and articles are effective as auxiliary intervention methods, but the specific types of videos or articles that are most effective still remain unclear. Current research has focused on the dynamic effect of various types of videos or articles on adolescents' anxiety levels, with the aim of finding suitable types of videos or articles to be used as materials during interventions. The study is divided into two phases. In the first phase of the study, a questionnaire was distributed to a total of 2120 participants from China regarding their anxiety level and their preferred materials during online surfing, The results indicate that five types of materials were related to adolescents’ anxiety levels. In the second phase of the study, Ecological Momentary Assessment was used to continuously measure 30 participants’ anxiety levels over the course of ten days. The results show that while scenic video, online fiction, classic literature, and literature criticism affected an individual’s emotions positively. There was no significant effect when entertainment videos were used. In addition, only scenic videos were able to alleviate anxiety in the long-term.

Business-cycle fluctuations in economic activity

2021 ◽  
pp. 105-125
Author(s):  
Jesper Rangvid
Keyword(s):  
Business Cycles ◽  
Business Cycle ◽  
Empirical Evidence ◽  
Economic Activity ◽  
Second Phase ◽  
Growth Trend ◽  
Business Cycle Fluctuations ◽  
The Business Cycle ◽  
Two Phases

This chapter explains what the business cycle is and what causes business-cycle fluctuations. We call fluctuations in economic activity around the long-term growth trend ‘the business cycle’. The business cycle consists of two phases. The first is a period of strong economic activity. The second, following the first, is a period of weak economic activity. We call the first phase of the business cycle an ‘expansion’ and the second phase a ‘contraction’ or ‘recession’. The chapter explains what causes business cycles, and examines the empirical evidence on the lengths and strengths of the typical business cycle. It finds that expansions typically last longer than recessions. The chapter also shows that the length of expansions has increased during recent decades.

Visual Processing of Contour Patterns under Conditions of Inattentional Blindness

2012 ◽  
Vol 24 (2) ◽  
pp. 287-303 ◽  
Author(s):  
Michael A. Pitts ◽  
Antígona Martínez ◽  
Steven A. Hillyard
Keyword(s):  
Visual Processing ◽  
Visual Awareness ◽  
Inattentional Blindness ◽  
Second Phase ◽  
Third Phase ◽  
Random Arrays ◽  
Visual Contour ◽  
The Difference ◽  
Two Phases ◽  
Task Irrelevant

An inattentional blindness paradigm was adapted to measure ERPs elicited by visual contour patterns that were or were not consciously perceived. In the first phase of the experiment, subjects performed an attentionally demanding task while task-irrelevant line segments formed square-shaped patterns or random configurations. After the square patterns had been presented 240 times, subjects' awareness of these patterns was assessed. More than half of all subjects, when queried, failed to notice the square patterns and were thus considered inattentionally blind during this first phase. In the second phase of the experiment, the task and stimuli were the same, but following this phase, all of the subjects reported having seen the patterns. ERPs recorded over the occipital pole differed in amplitude from 220 to 260 msec for the pattern stimuli compared with the random arrays regardless of whether subjects were aware of the patterns. At subsequent latencies (300–340 msec) however, ERPs over bilateral occipital-parietal areas differed between patterns and random arrays only when subjects were aware of the patterns. Finally, in a third phase of the experiment, subjects viewed the same stimuli, but the task was altered so that the patterns became task relevant. Here, the same two difference components were evident but were followed by a series of additional components that were absent in the first two phases of the experiment. We hypothesize that the ERP difference at 220–260 msec reflects neural activity associated with automatic contour integration whereas the difference at 300–340 msec reflects visual awareness, both of which are dissociable from task-related postperceptual processing.

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