Iterative Concept Research Articles

Chirp-coefficient bisection iteration method for phase-intensity reconstruction of chirped pulses

A new method is proposed to systematically measure the phase-intensity information of chirped pulses that is based on the chirp-coefficient bisection iteration (CBI) concept. Through the CBI procedure with measured spectrum and temporal intensity profiles (or intensity autocorrelations), spectral and temporal amplitude–phase information can be rapidly retrieved. We experimentally verified that our method has high precision for nanosecond- and picosecond-level pulses and low precision for femtosecond-level pulses. Our proposed method does not require a sophisticated setup and has the advantage of accurate determination of temporal and spectral chirp coefficients with various orders. It also has lower cost, simple operation, in particular covers a wider measurement range than the main current methods. Moreover, the retrieved waveforms can reveal both the pulse shape and the actual intensity with spectral and temporal chirped coefficients of various orders, which can be directly used in various pulse propagation analyses such as chirped pulse amplification.

Proof-of-concept of a questionnaire to understand occupants' comfort and energy behaviours: First results on home occupant archetypes

BackgroundThis paper demonstrates the effectiveness of the TwoStep cluster analysis and the development and first results of a new questionnaire for measuring comfort, health, and energy habits. The justification for the questionnaire is to consolidate into one instrument questions of six specific domains about occupants' energy consumption patterns, from the behavioural and psychological perspectives. MethodsThe questionnaire was developed from a literature review, iterative conceptualization, and testing. The resulting instrument was administered to a sample of home occupants, comprising of bachelor students of Architecture of the Delft University of Technology. The objective of the study was to examine the effectiveness of the TwoStep cluster analysis to produce occupant profiles. 316 emails were sent out inviting participants to complete the questionnaire. ResultsWith the TwoStep cluster analysis, it was possible to distinguish six different archetypes of occupants based on their behavioural characteristics. These were the Relaxed Optimists, Unconcerned Indifferents, Restrained Sensitives, Positive Absolutists, Incautious Negativistics, and Resigned Savers. ConclusionThe results provide promising evidence of the questionnaire's potential to distinguish different occupant energy consumption profiles based on distinct psychosocial domains in a single and concise instrument, while also showing that the analysis method is appropriate for the type of variables gathered. The value of recognizing these profiles allows for a better understanding of occupants' differing energy consumption patterns in their homes and tailoring interventions to their specific needs.

반복적 집합 개념과 그 문제들

반복적 집합 개념과 그 문제들

Why is the universe of sets not a set?

According to the iterative conception of sets, standardly formalized by ZFC, there is no set of all sets. But why is there no set of all sets? A simple-minded, though unpopular, “minimal” explanation for why there is no set of all sets is that the supposition that there is contradicts some axioms of ZFC. In this paper, I first explain the core complaint against the minimal explanation, and then argue against the two main alternative answers to the guiding question. I conclude the paper by outlining a close alternative to the minimal explanation, the conception-based explanation, that avoids the core complaint against the minimal explanation.

Experimental characterization of the gas injection nozzle for the ITER Neutral Beam Test Facility neutralizer

The gas supply for the neutralizer of the Heating Neutral Beam is designed to guarantee the establishment of the gas cloud needed to neutralize the negative ion beam, generated in the beam source, before it can be injected into the tokamak for plasma heating. To guarantee the proper function for optimal beam properties, an experimental validation of the analytical predictions of the gas flow behavior under the conditions of the test facility MITICA (Megavolt ITER Injector and Concept Advancement) was needed. Herewith the throughput properties of the designed gas injection nozzles had to be investigated as well as the behavior of the system in case of a sudden shutdown of the supply. These experiments have been performed at the modified TransFlow facility at KIT. Additionally, the experimental results have been compared with simulations and some effort was spent in order to find proper material and mounting options for the nozzles.

Maximality and ontology: how axiom content varies across philosophical frameworks

Discussion of new axioms for set theory has often focused on conceptions of maximality, and how these might relate to the iterative conception of set. This paper provides critical appraisal of how certain maximality axioms behave on different conceptions of ontology concerning the iterative conception. In particular, we argue that forms of multiversism (the view that any universe of a certain kind can be extended) and actualism (the view that there are universes that cannot be extended in particular ways) face complementary problems. The latter view is unable to use maximality axioms that make use of extensions, where the former has to contend with the existence of extensions violating maximality axioms. An analysis of two kinds of multiversism, a Zermelian form and Skolemite form, leads to the conclusion that the kind of maximality captured by an axiom differs substantially according to background ontology.

Automatic Facial Feature Extraction for Predicting Designers' Comfort With Engineering Equipment During Prototype Creation

Designers frequently utilize engineering equipment to create physical prototypes during the iterative concept generation and prototyping phases of design. Currently, evaluating designers' efficiency during prototype creation is a manual process that either involves observational or survey based approaches. Real-time feedback when using engineering equipment has the potential to enhance designers' efficiency or mitigate potential injuries that may result from incorrect use of equipment. Toward an automated approach to addressing these challenges, the authors of this work test the hypotheses that (i) there exists a difference in designers' comfort levels before and after they use a piece of engineering prototyping equipment and (ii) a machine learning model predicts the level of comfort a designer has while using engineering prototyping equipment with accuracies greater than random chance. It has been shown that the level of comfort that an individual has while completing a task impacts their performance. The authors investigate whether automatic tracking of designers' facial expressions during prototype creation predicts their level of comfort. A study, involving 37 participants using various engineering equipment, is used to validate the approach. The support vector machine (SVM) regression model yielded a range of R squared values from 0.82 to 0.86 for an equipment-specific model. A general model built to predict comfort level across all engineering equipment yielded an R squared value of 0.68. This work has the potential to transform the manner in which design teams utilize engineering equipment toward more efficient concept generation and prototype creation processes.

OUP accepted manuscript

This paper examines Quine’s set theory, New Foundations (NF), in the context of contemporary philosophy of set theory. Almost unanimously, philosophers of set theory now take the iterative conception, embodied in the axioms of Zermelo-Fraenkel set theory, to be the correct account of set. NF represents a more pragmatic methodology, where set theory is developed in response to the needs of mathematics rather than in accord with some prior philosophical conception of set theory. Quine’s approach provides a critique of the more metaphysical ones that have won out in the philosophy of set theory over roughly the last fifty years.

In-vacuum sensors for the beamline components of the ITER neutral beam test facility.

Embedded sensors have been designed for installation on the components of the MITICA beamline, the prototype ITER neutral beam injector (Megavolt ITER Injector and Concept Advancement), to derive characteristics of the particle beam and to monitor the component conditions during operation for protection and thermal control. Along the beamline, the components interacting with the particle beam are the neutralizer, the residual ion dump, and the calorimeter. The design and the positioning of sensors on each component have been developed considering the expected beam-surface interaction including non-ideal and off-normal conditions. The arrangement of the following instrumentation is presented: thermal sensors, strain gages, electrostatic probes including secondary emission detectors, grounding shunt for electrical currents, and accelerometers.

Cooperative MIMO precoding for the LTE-A D2D communications

In the current deployed 4G long term evolution-advanced (LTE-A) system, it adopts the precoding matrix to reduce the effect of the channel fading and improve the system capacity. Besides, a new technique of the device to device (D2D) communication enables the mobile devices using the LTE radio spectrum directly to communicate with each other. In this paper, two precoding selection methods are proposed for the multiple input multiple output (MIMO) D2D communications. The proposed methods adopt the subset and iterative concept to complete the precoding selection. Besides, a resource selection method is also provided for the D2D transmitter to select an appropriate spectrum resource among the nearby users served by the base station. Combined the resource selection with the proposed D2D precoding selection methods, both simulations and experiments demonstrate the excellent performance of the proposed methods.

Researchers Apply Lesson Study: A Cycle of Lesson Planning, Implementation, and Revision

Scripted lesson plans and/or professional development alone may not be sufficient to encourage teachers to reflect on the quality of their teaching and improve their teaching. One learning tool that teachers may use to improve their teaching is Lesson Study (LS). LS is a collaborative process involving educators, based on concepts of iteration and revision, to improve instruction. The initial use of an adapted version of LS referred to as a microteaching lesson study (MLS) is described in this article. Our purpose is to illustrate the process of MLS used by a group of researchers when developing lesson plans for teaching students with learning disabilities. We describe MLS, and then (1) share an application of MLS used by a research team in developing a writing intervention, and (2) discuss how the MLS format was mirrored with K‐12 teachers during professional development training.

Two key improvements to enhance the thermo-mechanic performances of accelerator grids for neutral beam injectors

The MITICA experiment (Megavolt ITER Injector & Concept Advancement) is the prototype and the test bed of the Heating and Current Drive Neutral Beam Injectors, which will be necessary for the full-performance exploitation of ITER. MITICA injector experiments shall demonstrate the reliable and accurate emission of a 17 MW beam of neutral particles for duration up to 1 hour, fulfilling ITER specific requirements.The accelerator grids are among the most critical parts of this experiment, because they must fulfill several operational requirements and at the same time satisfy the fatigue verifications according to the ITER Structural Design Criteria for In-vessel Components (SDC-IC). After about two years of continuous development, two design improvements were found to effectively increase the fatigue life of the grids up to the requested values. The first method was to adopt a novel shape of the cooling channels inside the grids, called Nozzle Island Cooling Enhancement (NICE) and able to provide a high performance cooling without exceeding the limits on the pressure drop through the grids. The second, called Stress Relieving Slits (SRS), was to introduce suitable slits in the grids, whose design was iteratively optimized until they were able to significantly reduce the stress/strain peaks due to thermal gradients.The NICE and SRS design solutions, here described in detail, were found to be key improvements in order to obtain a design of the grids able to satisfy all the operating requirements and all the structural verifications according to the ITER criteria.

An action research approach to early concept iteration in a design consultancy

This paper investigates early stage concept iteration within a design consultancy environment. The aim of this research was to outline and explore the importance of early phase concept iteration within the consultancy environment whilst highlighting the main influencing factors that lead to the iterative development stages of the design process. A literature review helped develop a theoretical framework for research into the concept of design iterations within the consultancy environment. An action research approach to concept iteration in product form design and development at the early stage of the design process was employed. It was found that budgetary constraints, time management and client expectations were determining factors in driving early concept iteration. Moreover, such findings may be of benefit and use to design researchers, consultants and design managers.

Preliminary design of electrostatic sensors for MITICA beam line components.

Megavolt ITER Injector and Concept Advancement, the full-scale prototype of ITER neutral beam injector, is under construction in Italy. The device will generate deuterium negative ions, then accelerated and neutralized. The emerging beam, after removal of residual ions, will be dumped onto a calorimeter. The presence of plasma and its parameters will be monitored in the components of the beam-line, by means of specific electrostatic probes. Double probes, with the possibility to be configured as Langmuir probes and provide local ion density and electron temperature measurements, will be employed in the neutralizer and in the residual ion dump. Biased electrodes collecting secondary emission electrons will be installed in the calorimeter with the aim to provide a horizontal profile of the beam.

Development and tests of molybdenum armored copper components for MITICA ion source

In order to prevent detrimental material erosion of components impinged by back-streaming positive D or H ions in the megavolt ITER injector and concept advancement beam source, a solution based on explosion bonding technique has been identified for producing a 1 mm thick molybdenum armour layer on copper substrate, compatible with ITER requirements. Prototypes have been recently manufactured and tested in the high heat flux test facility Garching Large Divertor Sample Test Facility (GLADIS) to check the capability of the molybdenum-copper interface to withstand several thermal shock cycles at high power density. This paper presents both the numerical fluid-dynamic analyses of the prototypes simulating the test conditions in GLADIS as well as the experimental results.

Design optimization of RF lines in vacuum environment for the MITICA experiment.

This contribution regards the Radio Frequency (RF) transmission line of the Megavolt ITER Injector and Concept Advancement (MITICA) experiment. The original design considered copper coaxial lines of 1″ 5/8, but thermal simulations under operating conditions showed maximum temperatures of the lines at regime not compatible with the prescription of the component manufacturer. Hence, an optimization of the design was necessary. Enhancing thermal radiation and increasing the conductor size were considered for design optimization: thermal analyses were carried out to calculate the temperature of MITICA RF lines during operation, as a function of the emissivity value and of other geometrical parameters. Five coating products to increase the conductor surface emissivity were tested, measuring the outgassing behavior of the selected products and the obtained emissivity values.

Final design of the beam source for the MITICA injector.

The megavolt ITER injector and concept advancement experiment is the prototype and the test bed of the ITER heating and current drive neutral beam injectors, currently in the final design phase, in view of the installation in Padova Research on Injector Megavolt Accelerated facility in Padova, Italy. The beam source is the key component of the system, as its goal is the generation of the 1 MeV accelerated beam of deuterium or hydrogen negative ions. This paper presents the highlights of the latest developments for the finalization of the MITICA beam source design, together with a description of the most recent analyses and R&D activities carried out in support of the design.

How children "add" or "restrict" entities and temporal spans in narrations: evidence from Italian and English native children

This work focuses on the acquisition of restrictive and (temporal and non temporal) additive means by Italian and English native children, especially including scope particles, together with children's progressing ability to build textual cohesion in a narrative text. In particular, the author tries to identify the age at which additive and restrictive means appear and the functions they carry out in discourse organization of very young subjects, as well as the cognitive operations the latter can use. Thanks to the consideration of two different languages, this work also explores the possible language-specific strategies exploited by the two groups of children. Part of the results can be read as age cognitive restrictions independent of the L1 of the child. Additive means appear from the age of four on but with some differences according to the types of quantification solicited, namely the quantification of entities and that of time spans: the 4-year-olds clearly have less problems in quantifying entities rather than time spans. In comparison with adult reference groups, Italian and English L1 children of any group exploit additive temporal means less frequently than means quantifying entities; the quantification of entities involving a negation shows up from the age of seven. From a cognitive viewpoint, the precocious emergence of entity contrasts by additive means is in agreement with what Givón (1995) maintains with respect to nominal referents (they are perceptually and cognitively more salient, they are acquired early in ontogeny and evolve early in phylogeny, they are culturally central entities etc.). Concerning negative particles, their later appearance is in agreement with some studies about negation showing the more problematic processing of negative structures by children with respect to the positive ones (cf. Giuliano 2004). Some other strategies identified in children's retellings are, conversely, to be interpreted as language-specific. The more frequent problems that Italian children have with the concept of iteration with respect to English L1 children could be due to the polyfunctional semantics of the Italian particles ancora ('more, again, still') and sempre ('always, again, still'); the late appearance of also in English L2 children's data, an internal positioning particle, is probably caused by the fact that English has an external, perceptually more salient particle, namely too, whose semantics is equal to that of also.

An enriched FEM technique for modeling hydraulically driven cohesive fracture propagation in impermeable media with frictional natural faults: Numerical and experimental investigations

SummaryIn this paper, an enriched finite element technique is presented to simulate the mechanism of interaction between the hydraulic fracturing and frictional natural fault in impermeable media. The technique allows modeling the discontinuities independent of the finite element mesh by introducing additional DOFs. The coupled equilibrium and flow continuity equations are solved using a staggered Newton solution strategy, and an algorithm is proposed on the basis of fixed‐point iteration concept to impose the flow condition at the hydro‐fracture mouth. The cohesive crack model is employed to introduce the nonlinear fracturing process occurring ahead of the hydro‐fracture tip. Frictional contact is modeled along the natural fault using the penalty method within the framework of plasticity theory of friction. Moreover, an experimental investigation is carried out to perform the hydraulic fracturing experimental test in fractured media under plane strain condition. The results of several numerical and experimental simulations are presented to verify the accuracy and robustness of the proposed computational algorithm as well as to investigate the mechanisms of interaction between the hydraulically driven fracture and frictional natural fault. Copyright © 2015 John Wiley & Sons, Ltd.

Bringing ecosystem services indicators into spatial planning practice: Lessons from collaborative development of a web-based visualization platform

Considerable efforts are made to integrate ecosystem services (ES) indicators into spatial planning practice. Although a lot of decision support systems already provide helpful functionalities, they are not yet integrated into everyday decision-making, mainly because they do not readily fit into planning processes in practice. There is an increasing awareness that the development should foster collaboration between interdisciplinary researchers and the end users of the tools to secure their suitability for such planning processes. Hence, user-oriented research and experimenting is seen as the appropriate approach for getting the tools ready for practice. Guidelines for conducting such processes are yet missing. Here, we contribute to the development of such guidelines by means of a practical case study. The focus is placed on how transdisciplinary (TD) research on spatial decision support systems should be designed for the integration of ES indicators into planning practice. In a TD project, a web-based visualization platform with indicators of relevant ES was developed to support municipalities of the Canton of Zurich, Switzerland, in assigning adequate watercourse corridors according to the revised Swiss Waters Protection Act. A preliminary as well as an enhanced version of the platform prototype were demonstrated to different actors for evaluating the platform's readiness for practice. We assessed the process design and the quality of the product in a discursive manner. Thereby, we implemented a set of assessment criteria derived from literature and adapted them to the case study at hand for the analysis of empirical material (participant lists, project schedule, meeting minutes and observation protocols). Finally, we discussed the lessons learned on developing significant ES indicators and their visualization and the conclusions drawn with respect to ensuring the quality of the platform development process. The results show that conceptualizing the ES indicators in strong collaboration with practice representatives increased their relevance to the actors’ needs and therefore their legitimacy. Providing interfaces for collaboratively translating practical approaches into scientific models is, thus, crucial for the development of significant indicators. Furthermore, specifying the purpose of the visualization platform in planning processes requires prototyping and iterative conceptualization, because practice actors need concrete examples to express their specific demands. This also requires that the concept of developing the ES indicators and the spatial decision support systems should be treated rather as an open working paper than as a final document agreed on in the first collaboration phase. Hence, time scheduling and occupying skilled project managers for this iterative process should be taken seriously.