process complexity
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Energies ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 621
Author(s):  
Fugang Zhai ◽  
Liu Yang ◽  
Wenqi Fu ◽  
Haisheng Tong ◽  
Tianyu Zhao

This paper investigates the electromagnetic torque by considering back electromagnetic force (back-EMF) trapezoidal degrees of ironless brushless DC (BLDC) motors through the two-dimensional finite element method (2-D FEM). First, the change percentages of the electromagnetic torque with back-EMF trapezoidal degrees, relative to those of PMs without segments, are investigated on the premise of the same back-EMF amplitude. It is found that both PM symmetrically and asymmetrically segmented types influence back-EMF trapezoidal degrees. Second, the corresponding electromagnetic torque, relative to that of PMs without segments, is studied in detail. The results show that the electromagnetic torque can be improved or deteriorated depending on whether the back-EMF trapezoidal degree is lower or higher than that of PMs without segments. Additionally, the electromagnetic torque can easily be improved by increasing the number of PMs’ symmetrical segments. In addition, the electromagnetic torque in PMs with asymmetrical segments is always higher than that of PMs without segments. Finally, two ironless PM BLDC motors with PMs symmetrically segmented into three segments and without segments are manufactured and tested. The experimental results show good agreement with those of the 2-D FEM method. This approach provides significant guidelines to electromagnetic torque improvement without much increase in manufacturing costs and process complexity.


Author(s):  
Patrick Schmidt

AbstractResearch into human uniqueness is gaining increasing importance in prehistoric archaeology. The most striking behaviour unique to early and modern humans among other primates is perhaps that they used fire to transform the properties of materials. In Archaeology, these processes are sometimes termed “engineering” or “transformative techniques” because they aim at producing materials with altered properties. Were such transformative techniques cognitively more demanding than other tool making processes? Were they the key factors that separated early humans, such as Neanderthals and early Homo sapiens, from other hominins? Many approaches to investigating these techniques rely on their complexity. The rationale behind this is that some techniques required more steps than others, thus revealing the underlying mechanisms of human uniqueness (e.g., unique human culture). However, it has been argued that the interpretation of process complexity may be prone to arbitrariness (i.e., different researchers have different notions of what is complex). Here I propose an alternative framework for interpreting transformative techniques. Three hypotheses are derived from an analogy with well-understood processes in modern-day cuisine. The hypotheses are about i) the requirement in time and/or raw materials of transformative techniques, ii) the difficulty to succeed in conducting transformative techniques and iii) the necessity to purposefully invent transformative techniques, as opposed to discovering them randomly. All three hypotheses make testable predictions.


2021 ◽  
Vol 2070 (1) ◽  
pp. 012013
Author(s):  
H Adil ◽  
A A Koser ◽  
M S Qureshi ◽  
A Gupta

Abstract Sleep quality measurement is a complex process requires large number of parameters to monitor sleep and sleep cycles. The Gold Standard Polysomnography (PSG) parameters are considered as standard parameters for sleep quality measurement. In the PSG process, number of monitoring parameters are involved for that large number of sensors are used which makes this process complex, expensive and obtrusive. There is need to find optimize parameters which are directly involve in providing accurate information about sleep and reduce the process complexity. Our Parameter Optimization method is based on parameter reduction by finding key parameters and their inter dependent parameters. Sleep monitoring by these optimize parameter is different from both, clinical complex (PSG) used in hospitals and commercially available devices which work on dependent and dynamic parameter sensing. Optimized parameters obtained from PSG parameters are Electrocardiogram (ECG), Electrooculogram (EOG), Electroencephalography (EEG) and Cerebral blood flow (CBF). These key parameters show close correlation with sleep and hence reduce complexity in sleep monitoring by providing simultaneous measurement of appropriate signals for sleep analysis.


2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Patrick Schmidt ◽  
Matthias A. Blessing ◽  
Tabea J. Koch ◽  
Klaus G. Nickel

AbstractBirch tar is one of the oldest adhesives known in human history. Its production has been discussed in the framework of early complex behaviours and sophisticated cognitive capacities. The precise production method used in the Palaeolithic remains unknown today. Arguments for or against specific production pathways have been based on efficiency or process complexity. No studies have addressed the question whether birch tar made with different techniques is more or less performant in terms of its properties. We therefore investigate the adhesive performance of birch tar made with three distinct methods: the open-air condensation method and two variations of underground structures that approximate the double-pot method in aceramic conditions. We use lap-shear testing, a standard mechanical test used for testing the strength of industrial adhesives. Tar made in 1 h with the condensation method has a shear strength similar to, although slightly higher than, tar made underground if the underground process lasts for 20 h. However, tars from shorter underground procedures (5 h) are significantly less strong (by a factor of about 3). These findings have important implications for our understanding of the relationship between the investment required for Palaeolithic birch tar production and the benefits that birch tar represented for early technology. In this regard, the simple and low-investment open-air condensation method provides the best ratio.


Author(s):  
Jaroslav Janáček ◽  
Michal Koháni ◽  
Dobroslav Grygar ◽  
René Fabricius

The public service system serves population spread over a geographical area from a given number of service centers. One of the possible approaches to the problem with two or more simultaneously applied contradicting objectives is determination of the so-called Pareto front, i.e. set of all the feasible non-dominated solutions. The Pareto front determination represents a crucial computational deal, when a large public service system is designed using an exact method. This process complexity evoked an idea to use an evolutionary metaheuristic, which can build up a set of non-dominated solution continuously in the form of an elite set. Nevertheless, the latter approach does not assure that the resulting set of solutions represents the true Pareto front of the multi-objective problem solutions. Within this paper, authors deal with both approaches to evaluate the difference between the exact and heuristic approaches.


2021 ◽  
Author(s):  
Amilcare Porporato

Abstract. By rigorously accounting for dimensional homogeneity in physical laws, the Pi theorem and the related self-similarity hypotheses allow us to achieve a dimensionless reformulation of scientific hypotheses in a lower dimensional context. This paper presents applications of these concepts to the partitioning of water and soil on terrestrial landscapes, for which the process complexity and lack of first principle formulation make dimensional analysis an excellent tool to formulate theories that are amenable to empirical testing and analytical developments. The resulting scaling laws help reveal the dominant environmental controls for these partitionings. In particular, we discuss how the dryness index and the storage index affect the long term rainfall partitioning, the key nonlinear control of the dryness index in global datasets of weathering rates, and the existence of new macroscopic relations among average variables in landscape evolution statistics. The scaling laws for the partitioning of sediments, the elevation profile, and the spectral scaling of self-similar topographies also unveil tantalizing analogies with turbulent fluctuations.


2021 ◽  
Vol 11 (16) ◽  
pp. 7743
Author(s):  
Panagiotis Stavropoulos ◽  
Panagis Foteinopoulos ◽  
Alexios Papapacharalampopoulos

The interest in additive manufacturing (AM) processes is constantly increasing due to the many advantages they offer. To this end, a variety of modelling techniques for the plethora of the AM mechanisms has been proposed. However, the process modelling complexity, a term that can be used in order to define the level of detail of the simulations, has not been clearly addressed so far. In particular, one important aspect that is common in all the AM processes is the movement of the head, which directly affects part quality and build time. The knowledge of the entire progression of the phenomenon is a key aspect for the optimization of the path as well as the speed evolution in time of the head. In this study, a metamodeling framework for AM is presented, aiming to increase the practicality of simulations that investigate the effect of the movement of the head on part quality. The existing AM process groups have been classified based on three parameters/axes: temperature of the process, complexity, and part size, where the complexity has been modelled using a dedicated heuristic metric, based on entropy. To achieve this, a discretized version of the processes implicated variables has been developed, introducing three types of variable: process parameters, key modeling variables and performance indicators. This can lead to an enhanced roadmap for the significance of the variables and the interpretation and use of the various models. The utilized spectrum of AM processes is discussed with respect to the modelling types, namely theoretical/computational and experimental/empirical.


2021 ◽  
Vol 17 (1) ◽  
pp. 404-407
Author(s):  
Laurenţiu GRIGORE

Abstract: Education is generally considered only a social process. Complexity, importance, flexibility and social security are strong arguments in defining education as a critical infrastructure. The educational system as a formal part of education is the one analyzed and the result fully gives education the status of critical infrastructure.


JOM ◽  
2021 ◽  
Author(s):  
Manuel Sparta ◽  
Vetle Kjær Risinggård ◽  
Kristian Etienne Einarsrud ◽  
Svenn Anton Halvorsen

AbstractControlling and optimizing smelting processes in submerged-arc furnaces are complicated by the limited amount of information available regarding the internal conditions. Computer models can help to bridge this knowledge gap. Due to the process complexity, computer models are commonly restricted to electrical conditions, thermal conditions, or chemical reactions, for instance. We have developed an overall model for a pilot-scale silicomanganese furnace that simultaneously considers electrical and thermal conditions, process chemistry, and flow of solid and liquid substances. To the best of our knowledge, this is the first comprehensive silicomanganese furnace model. The model has been compared to experimental data. Using information about the inner state of the furnace provided by the model, we are able to predict and explain an increase in temperature during over-coking as well as changes in the product compositions.


2021 ◽  
Author(s):  
Elena Lengthorn ◽  
Megan Asbury

Abstract Our urgent state of “Climate Emergency,” as declared by the UK Government on 1st May 2019, has done little to change our secondary education system or educational leadership. As we collectively begin to move into acceptance of the irreversible nature of a portion of the environmental damage and its long-term consequences, we need to explore the purpose and practice of education and educational leadership in climate emergency. How should we prepare teachers and educators to lead and develop young people in a time of climate crisis and who should be involved in making the decisions? This article reports on the findings of a Green Impact project, an online Educator Climate Assembly that took place on World Environment Day 2021, with West Midlands education stakeholder participants. The following themes are explored: responsibility, process complexity, confidence, sense of scale and communities of practice, with an invitation to readers to adapt this process and use it in their own education settings. Suggested further research includes trialing the process in a range of settings and a longitudinal approach to measuring the impacts.


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