bluuebunny/crossref_metadata_2025 huggingface dataset:
Teaching kinematics in two dimensions
Authors: Lawrence Ian
Published: August 2019

Kinematics has almost always been introduced in one dimension. This seems to have been more or less universally assumed to be the simplest way, with little explicit deliberation. This paper presents a suggested ‘teaching experiment’, as a contribution to the didactical debate, starting in two dimensions, arguing that this might well, provide a more fruitful route into the tautological complexities of kinematics. Some of the affordances exploited will be relatively recent, due to the current culture and availability of mapping and tracking technologies. Other suggested affordances will be conceptual and more evolutionary, as the barriers to thinking with vectors and about accumulations are now much lower if the potential for pedagogical support in representational and measurement technology is exploited fully. But perhaps the most significant reason to consider a change is that current practices and explanations could be improved. The spatialising of duration in Cartesian graphs may present further tripwires for learning. There are no guarantees here, and practice is rather resistant to change, but perhaps new thinking and new tools might make the topic more accessible: more children could then reason more fruitfully if given access to new tools for representing, reasoning and predicting.
Enacting planets to learn physics
Authors: Rollinde E , Decamp N
Published: August 2019

The Solar System motivates students to interest themselves in sciences, as a large number of concepts may be easily introduced through the observation and understanding of planet’s motion. Using a large representation of the Solar System at a human scale (“a human Orrery”), we intend to show how cognitive activities about kinematics and dynamics are activated and linked to the sensori-motors activities. In the last three years, we have conducted different activities with 10 to 16 years old children. In this contribution, we discuss the different scientific concepts covered by the Human Orrery, and the enaction theory that provides a theoretical background to those activities. We detail the enaction of velocity with a description of the gestures in relation with the abstract concepts involved in kinematics.
Role of graphs in the mathematization process in physics education
Authors: Pospiech G , Geyer M A , Ceuppens S , De Cock M , Deprez J , Dehaene W , Michelini M , Stefanel A
Published: August 2019

Using mathematical concepts to describe physical phenomena lies at the heart of physics. Literature however shows that combining physics and mathematics is challenging for students on all levels and therefore, the study of students’ ways to link both fields is a hot topic in Physics Education Research. In the process of mathematization graphs have a fundamental role not only in the context of scientific communication but also within the process of gaining knowledge. But there is evidence of serious difficulties of students in reading, understanding and constructing graphs. Therefore we bring together different approaches, employing mainly qualitative research methods, to understand how students deal with graphs related to the interplay of mathematics and physics, how the reasoning differs between mathematical and physical problems and how students connect graphical and algebraic representations to physical concepts. Especially we describe in detail - in different areas of physics - which difficulties with graphs students of secondary school experience and which strategies they employ. For this purpose we analyse the activities of 8th grade students in graphing, we study the learning of 9th grade students in an interdisciplinary teaching-learning sequence and we describe the development of physical-mathematical concepts through the use of graphs, generated with on-line sensors.
Student centered teaching activities in secondary schools and misconceptions evolution: basic mechanics
Authors: de Almeida M J , Martins D R , Sá M V , Pires A J , Tremoço J J
Published: August 2019

Based on constructivism and cognitivism we believe that learning physics in schools can be faced as a process of reshaping students’ mental models about Nature’s behavior. These can correlate with existing physics misconceptions. Aware of the negative consequences of basic cognitive misunderstandings and believing that their correction, implying active and motivated students, should start from first contacts with physics knowledge in lower secondary schools, we asked three schoolteachers to participate on a pilot study with 7th, 8th and 9th graders. This study is specifically designed to promote and coach teachers’ attitudinal changes towards stronger student centered teaching behaviors. We report results obtained during academic year 2017/2018, some qualitative (from teachers diaries and recorded interviews) and a quantitative quasi-experimental study (with pre- and post-tests and control groups) with 9th graders, searching for misconceptions evolution on basic mechanics. The results obtained with 15 out of the 30 questions of the Force Concept Inventory indicate a fairly high average normalized gain for the experimental group. However, this average gain was not uniformly distributed along every FCI question, evidencing some difficulties with Newton’s 3rd law understanding. A recommended approach for its teaching in 2018/2019 produced evidence of deep learning of every tested mechanics concept.
Teaching Physics in Primary School – Problematization as a basis for experimental activities
Authors: Railbolt B , Cruz-Hastenreiter R , Rodrigues F
Published: August 2019

This work presents preliminary results of an investigation about the use of experimental activities, from problematization, in physics classes to primary school students. It is proposed initially a reflection about how experimental activities based on solving problems can contribute to the teaching of sciences from a broader perspective. Based on this reflection, three experimental activities are proposed, starting from problem situations, where are presented concepts of Physics involved in the siphon effect, in the shadows formation and the rigid body equilibrium, directed to Elementary School. The proposal of the activities aims to explore conceptual, social interaction, epistemological and relationship with daily life dimensions present in didactic approaches based on inquiry-science teaching. In an empirical essay, we present some results of a didactic action. The construction of data from discursive interactions was used as a methodological reference, and content analysis was used as a data analysis tool. In the analysis of the results, recorded episodes were verified with the production of small texts and pictorial representations (drawings) made by the students.
University students’ causal reasoning dealing with RC circuits
Authors: Leniz A. , Zuza K. , Guisasola J.
Published: August 2019

This study examines university students causal reasoning when tackling electric current in transitory situations. A questionnaire with emphasis on explanations was used to analyse students’ reasoning. The results obtained show that a significant percentage of students cannot correctly interpret simple transitory state current phenomena. Their explanations fall into two general categories: one based on potential difference and one that excludes current flow in processes of transitory state. We look at a number of aspects that have been little mentioned in previous research, for example, the reasoning university students use when establishing macro-micro relationships and some difficulties with complex reasoning.
Experiments with Kundt’s tube
Authors: Macho-Stadler Erica , Elejalde-García Maria Jesús
Published: August 2019

We present some lab science experiments that are intended to be performed by undergraduate university students of scientific and technological disciplines. We come out with an experimental study of waves in Kundt’s tube by varying the absorption characteristics of its closed end. The measurement of the resonant frequencies permits to determine the speed of sound in the tube. The impedance tube-standing wave method (ISO-10534-1) is applied to study the normal absorption coefficient of acoustics insulators. The setup includes basic lab equipment available in the undergraduate laboratory: a tube, a speaker, a microphone, a digital function generator and an oscilloscope.
Addressing undergraduate students’ difficulty in learning the Generalized Work-Energy Principle in introductory Mechanic
Authors: Gutierres-Berraondo J. , Guisasola J. , Zuza K.
Published: August 2019

In this contribution, we report the implementation and evaluation of a interactive Teaching Learning Sequence (TLS) introducing the concepts of Work, energy and the relations between them. The sequence has been designed with the Design Based Research (DBR) methodology. In order to analyse the effectiveness of the Sequence for students to be able to achieve the set learning goals, a pre-post test was designed. We was given the questionnaires, over two academic years (14/15 and 16/17), to about 170 students who attended the introductory physics course for the first engineering degree. Our findings show that the majority of experimental students’ progress from particular cases of the relation between work and energy towards an explanatory general relation between work and energy. We discuss implications of our findings in relation to teaching work and energy in introductory physics courses
Promoting active learning in physics courses for the agro-food degrees1
Authors: Stefanel A
Published: August 2019

Teaching/learning physics in the bio area require a revision of contents, approaches, methods. In the last years at the University of Udine, an experimentation was carried out in the physics course for the agro-food degrees. The main choices will be discussed, highlighting the basic role of active learning proposals and continuous assessment
Physics for non-physicists - two bio-degrees reforms in Spanish universities: Health Biology and Biology
Authors: Herrera-Melle L , Cussó F , Lifante G , del Romero A , Sancho M
Published: August 2019

We present a review of two different innovative experiences of Physics education for Bio-Sciences in two Spanish Universities - the Health Biology degree of the Universidad de Alcalá de Henares (UAH) and the Biology degree of the Universidad Autónoma de Madrid (UAM). Both experiences took place simultaneously and coincident with the implementation of Bologna Plan. Although they were developed under different contextual constraints, set by the respective Faculties, they share a number of similar pedagogical strategies which are analyzed. In both cases the reforms allowed a substantial improvement in learning results compared to those obtained in the previous Physics courses in the respective degrees.
Using neuroscience evidence to train pre-service physics teachers on the concepts of heat and cold
Authors: Ezquerra A , Ezquerra-Romano I
Published: August 2019

Teachers must identify, manage and modify alternative conceptions in their students. However, research consistently highlights that future teachers prioritise disciplines’ requirements rather than the educational needs of children. Moreover, some researchers have proposed that the way our senses work shapes the development of children’s ideas. Neuroscientists have only recently started to understand how the senses transduce and transmit stimuli. In this study, we show an innovative initial training course of Didactics of Physics, which includes the latest understanding of the thermosensory system. We analysed the progression of the educational proposals written by future teachers. This analysis revealed the effect of integrating neuroscience contents in the initial training. We found that the neuroscience insights helped future teachers incorporating children’s misconceptions in their proposals. Additionally, they lowered their expectations and became less frustrated. They understood that it is not expected to quickly modify pupils’ alternative conceptions because they have a physiological component.
Lights and shadows in Physics teaching. Contributions of an action research experience
Authors: Lescano A J , Sánchez G H , Lorenzo M G
Published: August 2019

The aim of this paper is to find a teacher’s concerns, difficulties and knowledge construction when he begins to be part of the field of science education research. Pedagogical Content Knowledge (PCK) model and the Content Representation instrument (CoRe) offer a significant theoretical and methodological framework to carry out this kind of study using action-research perspective. Metacognitive knowledge, critical thinking and reflection were used to describe the process and changes of the teacher. Based on a particular experience carried out for the teaching of spectroscopy in secondary school level Physics lessons, a reflection is raised on the practice itself aimed at transforming the teaching task into an object of action - research for the teacher. The processes involved in the selection of the topic, the basis for the design and implementation of the practical activity and the observations of the teacher are described. The results have shown the influence of the teacher intentions and knowledge on his PCK development by means of searching for the best way to design the class for particular students in a particular context. These are a first step to lighten the shadows on the journey to become a Physics education researcher.
A guide on models and modelling
Authors: Heck A , Uylings P , van Weert C
Published: August 2019

A new curriculum and examination programme for upper secondary school physics was recently introduced in the Netherlands. Models and modelling play an important role herein. But teachers need help in developing their PCK in this area. To this end we developed a modelling guide, which introduces physics teachers to the role of modelling in science and science education, the scientific base of teaching and learning routes of modelling in pre-university education, and curriculum relevant computer models. We discuss the design and contents of this guide, and teachers’ first impressions when it was presented to them in workshops.
A transversal educational proposal for prospective primary teachers: the theme of Time
Authors: Michelini M , Bozzo G , Vidic E , Monti F
Published: August 2019

Time is a transversal topic that plays a fundamental role in our every-day experience and represents a natural conceptual bridge between common sense ideas and scientific knowledge. Two classes of Prospective Primary Teachers (PPTs) at the Universities of Udine and Verona were introduced to the theme of Time in a formative intervention organized into a) the discussion of various educational and multidisciplinary approaches aimed to deal with different aspects of Time and b) the exploration/experimentation of various instruments for time measurement. In this work, we study and compare the learning outcomes in terms of planning and implementation of educational projects built by PPTs following two different Rubrics.
A longitudinal study on the imaginary of future physics teachers about ‘learning assessment’
Authors: Nardi R , Belíssimo J R , Parma F W
Published: August 2019

We present here partial results of a broader study aimed to investigate details of the initial education of Physics teachers, seeking to analyse the representations of these future high school teachers, from admission until their graduation from university, in order to understand how research has been introduced in or affected their early training. In this sense, we sought to analyse the profile of these future teachers and their imaginaries about “scientific knowledge”, “science teaching” and the “constitution of teaching knowledge”, from the moment of joining university in 2014 until the completion of the programme in 2017. Data collection took place in accord with a qualitative approach, using questionnaires applied at the beginning of each academic year in the specific courses of the programme. The data were treated by Discourse Analysis, originated by Pêcheux and developed in Brazil by Orlandi and other researchers. In this paper, we highlight the meanings produced in the discourses of future teachers on the theme “learning assessment”. The discourses show that the conditions of discourse production were fundamental in the changes of the future teachers’ imaginaries about this theme, and the power and impact that the programme and the institution have on the future teachers.
Hands-on experiments in the interactive physics laboratory: A study of students’ intrinsic motivation
Authors: Snětinová M , Kácovský P
Published: August 2019

Experiments in different forms can be suitable tools how to increase students’ interest in physics. However, educators discuss which ways of experimenting are the most beneficial for these purposes. At our department, two different forms of physics experiments are offered to upper secondary students – students’ hands-on experimental work and physics demonstration shows where the students watch experiments conducted by a lecturer. Our research aims primarily at students’ feedback about their immediate attitudes towards the hands-on experimenting and differences in perception of this experimenting and watching the lecture demonstrations. For collecting data we used a questionnaire based on Intrinsic Motivation Inventory.
The educational role of a scientific museum: a case study
Authors: Rinaudo Marta , Leone Matteo , Marocchi Daniela , Amoroso Antonio
Published: August 2019

The purpose of this work is to present an ongoing physics education project based at the Museum of Physics of the University of Turin, whose goal is studying the educational significance of the history of physics. The major targets of this project are: compiling a census of the collections of instrument of historical-scientific interest preserved by a significant sample of schools in Piedmont, Italy; designing experimental activities rooted in the development of the physics instruments displayed in the Museum and in the school collections detected; finally, testing the efficacy of these activities.
High school students’ epistemological approaches to computer simulations of complex systems
Authors: Barelli Eleonora , Branchetti Laura , Ravaioli Giovanni
Published: August 2019

The science of complex systems can provide not only scientist, but also professionals, policy-makers and citizens, with thinking resources to interpret and understand most of the modern global challenges. In this field, the widespread use of computational simulations, that are neither theoretical instruments nor laboratory experiments, has been contributing to the widening of the scientific skill gap between experts and citizens. The pilot study we present in this contribution aims at investigating high school students’ approaches towards simulations of complex systems, by searching for the criteria they use to evaluate their explanatory power and the reliability of their results. Preliminary analysis of the paired interviews has shown that (1) rarely students are able to elaborate explanations of the simulated complex phenomena, and (2) their critical attitude and trust towards simulations are strongly affected by their epistemological background. We argue that these findings deserve to be furtherly investigated, to understand in more details the sources of students’ difficulties in recognizing the epistemological and methodological value of simulations for scientific research and practice.
Model-based simulation design for the students’ conceptual understanding of introductory thermodynamics
Authors: Meli Kalliopi , Koliopoulos Dimitrios
Published: August 2019

The present study refers to the design principles of an educational simulation for the introductory physics level and their application on a recently developed simulation (IGasES: Ideal Gas Educational Simulation) for classical thermodynamics and specifically for the First Law of Thermodynamics. These principles rely on three modeling aspects (physics teaching, learning and educational simulations) and their convergence for the construction of a model-based educational simulation. The study also reviews some of the issues that commonly used simulations encounter for the teaching and learning of this topic. For addressing these issues, we choose the energy chain model as a proper representation of a thermodynamic system for mediating between the phenomenology and the mathematical expression of the First Law. In conclusion, this study draws attention on the characteristics of the educational software rather than the way they are put in use and also to the modeling procedures than can facilitate the student’s conceptual understanding.
Towards a teacher dashboard design for interactive simulations
Authors: López Tavares D , Perkins K , Kauzmann M , Aguirre Velez C
Published: August 2019

The use of interactive simulations (sims) in physics education is increasing. Aside from direct observation, teachers currently lack options for gaining useful insights into how their students are using these sims. A teacher dashboard to analyze and visualize student interaction with sims holds promise for responding to teacher needs and providing opportunities for improved classroom implementation of such sims. In this work we present progress in the design and development of a teacher dashboard that analyzes and visualizes student interaction with sims. A survey of over 800 teachers was conducted to identify the types of information teachers’ perceive as useful and how they would use that information to guide instruction. Teacher report valuing information that helps them to review student performance, to improve the design of sim-centered activities, and to plan lessons. A prototype dashboard design informed by this survey is also presented, including data collected from student sim use during a college homework activity. Finally, we describe how this dashboard design can address teacher needs related to insights around sim-based activities. Future work will evaluate teacher opinions regarding their interpretation of the data visualizations and the dashboard design in general.
pml – a language for authoring and editing physics text
Authors: Lawrence Ian
Published: August 2019

Expressing physics on a web page with the fruitful precision required in order to best support learning tends to be a demanding technical task for authors and content curators. That is as a result of the need to adhere to various conventions, such as the spacing between numbers and units, and ensure that unhelpful distributions of words do not detract from meaning, such as splitting equations over lines, or placing number and unit on different lines, whatever the display device. In short, there is a lot to get right. Current standards in markup languages such as html do not lend much support to avoiding of these kinds of mis-steps. Some current techniques suggest a mixture of technologies, such as embedding LATeX via MathJax to represent equations, but this is inelegant, introduces dissipative friction into the authoring and editing systems, and results in extra difficulties in separating content from display technologies whilst ensuring representational consistency across the different technologies deployed. A system using this physics markup language can be implemented using standard web technologies (generating clean, standards-compliant and mobile-friendly html, with hooks for CSS, and relying only on JavaScript) and authoring can be in any text editor.
Learning Physics with Interactive Videos – Possibilities, Perception, and Challenges
Authors: Richtberg Stefan , Girwidz Raimund
Published: August 2019

Videos on YouTube are very popular among students and therefor the number of educational videos is growing. In general, such videos are a learning opportunity with unique features like visual highlighting or multiple representations and can be watched as often as you like. Moreover, videos can be used in many different ways: to repeat things, to learn something new, or for entertainment. Here the paper presents a study among n=260 German students to determine how often and why students are watching educational videos in Physics, Chemistry, and Biology. Furthermore, the study shows unfortunately that students often just watch learning videos passively; whereas, learning needs an active processing. So making already available online videos more interactive with tasks, questions, and quizzes can foster an active processing and students should perceive interactive videos as more helpful when learning online. To do so the paper presents the free and open source tool H5P, which can be easily used by every teacher to enrich learning videos with tasks, feedback, summaries, or additional information.
The Augmented Laboratory – a mixed reality setup for physics education
Authors: Rosi T , Onorato P , Oss S
Published: August 2019

We discuss an educational project, The Augmented Laboratory, aimed to bring innovation in educational physics laboratories in formal and informal contexts. It is based on the capability of obtaining 3D reconstructions of the physical world which can be visualized both live as the data is acquired and later on as interactive playbacks. The setup allows to obtain 3D tracking of multiple objects, to project data of interest directly on and around the objects used in a real experiment, and to introduce the new concept of “augmented experiments”. The setup was tested with a group of university students and as a scientific exhibit for hands-on activities.
Newton’s Law - A Theory of motion or force?
Authors: Goren Ehud , Galili Igal
Published: August 2019

Regular disciplinary instruction of introductory physics at high school often misses a holistic perspective of the subject matter, its structure and hierarchy. We have considered the domain of mechanics and provided such a perspective in a summative lecture by framing mechanics contents in discipline-culture framework. In the experimental teaching, we focused on Newton’s laws of motion as the nucleus of classical mechanics. Considering mechanics as a culture, that is, addressing the debate with periphery conceptions, caused students to appreciate the fact that mechanics is about theory of motion, while forces present only a certain conception to account for it.
Phenomenon-based learning and model-based teaching: Do they match?
Authors: Grusche Sascha
Published: August 2019

The goal of physics teaching is to guide students from their everyday conceptions and activities to scientific models and practices. In essence, there are two different ways toward that goal: Phenomenon-based instruction and model-based instruction. Phenomenon-based instruction has been characterised by subjectivity, affectivity, mediation, exploration, and restrained model use. By definition, model-based instruction must be described by diametrically opposed characteristics: objectivity, rationality, confrontation, hypothesis testing, and extensive model use. Thus, the physics teacher may think that the two methods of teaching and learning do not match. However, we will see that both methods can be combined to guide students stepwise from phenomena to models.
A Rapid 3D-Modeling Method for Impeller of Wind Turbine
Authors: Wu Weimin , Zhou Chuande , Liu Jingcheng , Wang Xiaomei , Yang Yonggang
Published: August 2019

It is a very important fundamental work that 3D-model of impeller for wind turbine can be achieved precisely, in order to enhance the credibility of CFD analysis in subsequent calculations. However, the current studies do not emphasize closely on the modeling with time-saving and high efficient. Therefore, one high efficient approach for geometric modeling of wind turbine impeller is proposed by this study, and the validity of logical framework and pseudo-code of each part correspondingly is confirmed through several applications upon modeling of impeller, with time-efficient to shape in the process-designed. Moreover, the validity concerning CFD solution is verified by CFD computations of wake of a wind turbine. Additionally, the high efficient approach is also suit for a wider spectrum in fluid machinery for the modeling of relevant entities, and especially for performing such optimal modeling associated with high efficiency, in terms of concise readjustment to grammar and related modeling operations in the logical framework proposed by this paper.
Study on Thermal Performance of Single-layer and Multi-layer Stone Aluminum Honeycomb Composite Panels
Authors: Wu Miaomiao , Liu Jiahao
Published: August 2019

The stone aluminum honeycomb composite panel is light in weight and large in ductility. It is a sustainable building thermal insulation material. It can be used as an insulation wall for ordinary buildings and prefabricated buildings, so that the exterior walls of the building can be light, high-strength and heat-insulated. However, the current application of stone aluminum honeycomb composite panels is still rare in practice, because the reasonable core size and number of layers with the best structural optimization, the least heat transfer, and the strongest applicability are difficult to determine. In this paper, the three basic heat transfer mechanisms of heat conduction, thermal convection and heat radiation of stone aluminum honeycomb composite panel structure are systematically analyzed. Under the premise of convective heat transfer of gas in honeycomb core cavity, the surface radiation exchange of honeycomb core cavity is established. The heat and the heat transfer of the cavity and the air in the cavity play a leading role in the heat transfer mechanism. The effects of parameters such as honeycomb core layer, core size, core height and core wall thickness on heat transfer performance under steady-state heat transfer conditions were studied by experimental methods. Stone aluminum honeycomb composite panels were tested under different temperature conditions. The equivalent thermal conductivity of the structure. Based on the ANSYS finite element analysis software, based on the experiment, the fluid-solid coupling heat transfer model of stone aluminum honeycomb composite board was established to simulate the steady-state heat transfer performance of composite sheets under single-layer and multi-layer honeycomb core materials, and to study the core body. The variation of the effective thermal conductivity under different boundary conditions and different geometric parameters, the simulation results are basically consistent with the experimental results, and the results of the empirical formula are also consistent. The results show that under the condition of satisfying the feasibility of the construction process within the fixed height, the height of the honeycomb core layer, the size of the core, and the height of the core can be appropriately reduced to reduce the thermal conductivity.
Numerical Simulation of Large Crude Oil Storage Tank Fire under Various Wind Speeds
Authors: Zhou Feng
Published: August 2019

In order to analyse the influence of the wind speed on the fire characteristics and hazards of large crude oil storage tanks, this paper used the fire dynamics simulation software FDS to simulate the fire of a large crude oil storage tank under various wind speeds. The fire characteristics such as flame, smoke and temperature distributions of the tank under different wind speeds were studied. The thermal effects on the adjacent tank and the way that the firefighters cool the hazardous area were discussed. The results show that with the increase of the wind speed, the flame, smoke and temperature distributions shift and spread downwind. When tank fire occurs, the firefighters should set up movable firefighting water gun near the dangerous area and lay fire water hose to the burning tank and its neighbours, which provides a good preparation for the subsequent firefighting operation near the burning tank.
Coupled CFD-DEM Simulation of Tea Particles in a Cylinder Fixation Equipment
Authors: Luo Jie , Liu Yunwen
Published: August 2019

This paper presents a coupled CFD-DEM approach to simulate the process of tea fixation in a cylinder fixation equipment. We have carried out quantitative assessments of process conditions, such as rotation speed, number and height of lifter and drum tilt. The temperature and movement charatertristic of particles in the drum are obtained and analyzed. We assess the performance of our framework by employing temperature rising rate, which presents the efficiency of heat transfer between hot air and particles. An orthogonal experiment with four factors and three levels was designed, and the results show that the rotation speed and drum tilt have great influence on the temperature rising rate of tea particles, and the number and the height of lifter had little influence on the temperature rising rate. Finally, we have identified a lifter of 14 pieces and 70 cm height, a rotation speed of 20 r/min and a drum tilt of 3 degrees as a set of optimal operating conditions.
Numerical Simulation of Erosion of Valve Sealing Surface by High Speed Water Flow Based on ALE Method
Authors: Wang Dongdong , Yu Xinhai
Published: August 2019

With the development of modern industry, more and more valves need to be serviced under severe working conditions. Due to the high-speed flushing of working media, the failure of valve sealing surfaces is not uncommon. Based on the ALE (Arbitrary Lagrange-Euler) algorithm, LS-DYNA is used to simulate the erosion of the valve sealing surface material Stellite21 by high-speed water flow, and the damage degree of grid unit is judged by the damage parameter D. At the same time, the parameters of Stellite21 in the Johnson-Cook material model were first calibrated. In this paper, the impact dynamics simulations of different impact angles and different impact velocities were carried out and the material behaviour under different operation parameters of water jet is studied. It is found that with the increase of impact velocity, the erosion rate of materials has a significant increase. As impact angle increases, the erosion damage rate increases first and then decreases, and material has the maximum erosion damage rate at the impact angle of about 40°.
Design optimization and analysis of a vaned diffuser based on the one-dimensional impeller-diffuser throat area model
Authors: Hong Enyu , Ban Haibo , Qi Mingxu
Published: August 2019

The paper presents a design optimization method for a type of centrifugal compressor’s vaned diffuser with using a one-dimensional (1D) mathematical model to determine the best throat area ratio of the impeller to the diffuser. The research aims to verify of the 1D throat area mathematical model and to study the influence of vaned diffuser structure on the impeller-diffuser matching and the stage performance. The results of CFD analysis and experiments have proved that 1D throat area model can predict the throat area ratio of the impeller to the vaned diffuser accurately for the same choking mass flow at the required rotating speed. After optimization, the compressor performances and the matching between impeller and vane diffuser are considerably improved as well. The results and conclusions indicate that quick geometry modification of vaned diffusers can achieve excellent performance optimization and provide the theoretical basis for the selection of variable vaned diffusers.
Motion response analysis of mining vessel based on ANSYS/AQWA
Authors: Xu Hailiang , Neng Peng , Yang Fangqiong
Published: August 2019

To analyse the motion response of mining vessel under complex sea conditions and provide theoretical support for the design of heave compensation system, the hydrodynamic analysis software AQWA of three-dimensional potential flow theory was used to analyse the time-frequency response characteristics of mining vessel under the coupling of wind, wave and flow. The response amplitude operator (RAO) of the hull at different wave angles and the six-degree-of-freedom motion response of the hull at different currents were obtained. The results show that the wave angle has an influence on the Rao in the six degrees of freedom, but the frequency corresponding to the Rao peak is relatively close; the time domain analysis results show that the hull roll motion response is larger than the pitch; the maximum response angle of the roll is up to 4°; the effect of sea current velocity on swing, sway, and heave direction is different; the statistical average of wave force in different degrees of freedom is also affected by the wave angle. The simulation results in this paper can provide theoretical guidance for the design of multi-dimensional wave compensation system in mining system. Therefore, when designing wave compensation system, it is necessary to consider the influence of different situations.
Comparative Analysis of Hydrodynamic Performance of Propeller Under Different Turbulence Models
Authors: Zhou Xiaoming , Pan Huachen , Tian Xiaoqing , Zhu Zefei
Published: August 2019

In order to study the applicability of different turbulence models in the prediction of propeller hydrodynamic performance, computational fluid dynamics software CFX was used to simulate the thrust coefficient, torque coefficient and efficiency of VP1304 propeller under specific viscous flow field conditions by using k - ε models, k - ω models, SST models and RSM models respectively. The prediction results from the four turbulence models are compared with the experimental data of controlled pitch propeller VP1304 published by SVA Potsdam. It is concluded that the simulation prediction of performance due to the RSM model is the most accurate, Merits and demerits of RSM model is analyzed.
Analysis on Mechanical Properties of Single Conductor Considering Flexural Stiffness under Wind Load
Authors: Wang Xinxin , Zhao Jianpin , Zhao Puzhi , Zheng Yi , Yu Guoqing
Published: August 2019

In order to study the effect of flexural stiffness on the mechanical properties of single conductor under wind load, a configuration function of the conductor considering stiffness is established in this paper. Based on the configuration function, the finite element model is established, and the effects of suspension point angle, span on the mechanical properties of down lead conductor under wind load are studied. The results show that, compared with the catenary model, the model in this paper is more consistent with the experimental fitting formula. The angle of the suspension point has obvious influence on the tension of down lead conductor. With the increase of the angle of the suspension point from 0°to 80°, the tension decreases by nearly one third. The bending moment is affected by the alignment, and the reverse sign appears with the increase of suspension point angle. When the redundancy rate is the same, the span increases from 2 m to 4 m, and the tension of the conductor decreases by 18%.
Prediction of hydrodynamic characteristics of combined propellers based on CFD method
Authors: Su Shichuan , Wang Shengsen , Cao Jiabin , Feng Desheng
Published: August 2019

In recent years, with the concept of “green ship” put forward, it has been a major task for ship workers to improve ship propulsion efficiency and save fuel consumption. Combined propellers show higher propulsion efficiency and better energy saving effect, so they are favored by ship workers. This article using the computational fluid dynamics (CFD) software to the single propeller, tandem propellers and contra-rotating propellers was simulated in different speed coefficient, and forecast the propeller hydrodynamic performance, comparing single propeller, tandem propellers and contra-rotating propellers open water efficiency shows: the contra-rotating propellers and tandem propellers rear blade absorbing front blade axial velocity and trailing vortex energy, increase propeller thrust, to improve the efficiency of the propeller propulsion, energy conservation and emission reduction has important significance, also conforms to the concept of “green design” of the ship.
Temperature field modeling of the plate during hot rolling based on inverse heat conduction problem
Authors: Liu Wenhong , Guo Siying , Zhang Siyu
Published: August 2019

In the established temperature field model of plate hot rolling process, the heat transfer coefficients of each stage are solved by empirical formula, but due to the complexity of the production environment, temperature field models tend to be less accurate. In order to solve this problem, this paper designs a rolling experiment, collects the actual temperature data, and combines with genetic algorithm, simulated annealing algorithm and particle swarm optimization algorithm to correct the heat transfer coefficients of air-cooling zone, and the three algorithms are compared. Finally, the particle swarm algorithm is selected to establish the temperature field model of the hot rolling process. The average error of the final temperature field model calculation is within 14°C.
Vortex Shedding Mechanism of Post Cyclone-Bluff Body Stabilized Combustion
Authors: Wu Yunke , Li Zhiqiang , Zhang Zhihong , Liu Lifang , Wang Yuruo
Published: August 2019

V-gutter is one of the typical bluff bodies that often used for flame stabilization in the afterburning chamber of present turbine engine. For its small range of lean/rich fuel limits, weak anti disturbance capability and low combustion efficiency which may cause the flame in combustion chamber easily to be extinguished, the V-gutter still needs to improve performance. In this paper, a new method that adding a cyclone behind the bluff body to enhance the flame stabilization by the interaction of shedding vortex of bluffs body and this cyclone is proposed. Vortex shedding mechanism of the flow around V-gutter with post cyclone is studied. The numerical result shows that the post cyclone has an important impact on the vortex shedding mechanism of the flow around V-gutter. The flow resistance and fluctuation are reduced and the length of the recirculation zone is increased, which can lead to the improvement of the flame stabilization. On the contrary, the flow resistance and fluctuation increase, and the recirculation zone become shorter when the post cyclone source is outside, which is negative to the flame stabilization. The influence of the post cyclone diameter cannot be ignored either. The flow resistance is increased, the fluctuating characteristic is strengthened, the recirculation zone is shortened and the vortex shedding frequency is decreased when the cyclone diameter is increased.
Flume Experiments on the Oscillating Wall Jet Induced by the Swing Oblique Impingement Jet
Authors: Zhao Peng , Zhang Minxi , Yu Guoliang
Published: August 2019

The flow characteristics of oscillating wall jets induced by swinging an oblique impingement jet in a rectangular flume is experimentally investigated. By using ultrasonic Doppler velocity profiler (UDVP), the phase-dependent velocity profiles, the phase-varying turbulence fluctuations, and the decay of the velocity along the downstream surface of the oscillating wall jets are observed in a two-dimensional plane. Results show that the mean velocity profile of the oscillating wall jet in the near-bed region generally follows the Weibull distribution, similar to the steady wall jet. Greater fluctuation magnitudes are produced by the oscillating wall jet at the low-speed provocation and high-speed suppression phases than that at the accelerating and decelerating phases. The velocity fluctuations increase with the increasing oscillating frequency. Both the oscillation offset and amplitude of the oscillating wall jet decay continuously with the spreading distance. The decay rate of oscillation offset along the downstream wall of the oscillating wall jet is higher than the velocity decay rate of steady wall jet, and slightly increases with the increment of the oscillating frequency. The oscillating amplitude decays exponentially with the downstream distance.
High Temperature Operation Clothing Design Based on Heat Conduction Equation
Authors: Pan Wenwen , Wang Ying , Shang Yushen , Zhang Liqin
Published: August 2019

Based on the knowledge of heat and mechanics, the relationship between density, specific heat, thermal conductivity and thickness is analyzed by means of heat conduction equation. Under the condition of the change of working time and temperature, the optimal two-dimensional spline interpolation method is used to construct the corresponding functional relation of the temperature distribution field, and based on the numerical model of multi-zone and multi-layer heat transfer of the dummy in the equipment. The thermal physical parameters of each region are determined by experiments, and the equations of thermal equilibrium are established. Under the condition of the problem, the temperature change outside the human body is obtained, and then the temperature distribution outside the human body is obtained. Based on the above model, the experimental results show that the heat absorbed by the outside is consumed layer by layer in the process of heat transfer at high temperature. The following known temperature distribution, at a specific ambient temperature and working time length, the thickness of layer II to layer IV is obtained. By using multi-objective programming and genetic algorithm, the optimal solution is obtained by iterative approximation of the optimal solution for many times, and the final data is obtained by using the method of multi-objective programming and genetic algorithm.
The influence of the guide vane angle of the turbocharger on the turbine mechanical properties and flow field characteristics
Authors: Zhang Shiqiang , Li Chunshu , Fan Liwei
Published: August 2019

Turbocharged gasoline engines produce less exhaust gas when running at a low speed, which is not enough to make the turbine rotor run at a high speed and press in enough air. By changing the cross-section area of the exhaust gas inlet and controlling the gas flow velocity, the turbine can achieve a larger rotation speed with less exhaust gas. Croe2.0 3D software was used to build the 3D model of the adjustable turbine device. ANSYS software is used to analyze the stress of turbocharger turbine. By adjusting the gas flow rate, the adjustable turbine device can significantly change the numerical value of the turbine force, which improves the problems faced by turbocharging engine at low speed and provides theoretical basis for the adjustable turbocharging technology.
Research on optimization of dust measurement pipeline based on Bernoulli Effect
Authors: Liu Dandan , Jing Mingming , Li Dewen , Wang Jie , Tang Chunrui , Ma Wu
Published: August 2019

According to the principle of Bernoulli Effect in fluid mechanics, a dust measurement pipeline with Bernoulli Effect is designed. According to the previous research of the projec, this paper simulates by CFD software, obtains the particle motion velocity and electrostatic induction under different pipe diameter ratio, and finds out the maximum electrostatic induction under the better tube diameter ratio. The annular electrostatic sensor is used to find a better diameter ratio for Bernoulli Effect tube. The improved device model with different pipe diameter ratio was established in Gambit2.4, and 2D stereo model was used for experimental simulation. The velocity cloud map of particle motion is obtained by using FLUENT6.3 to solve the problem, and the corresponding velocity value is obtained according to the cloud image. The electrostatic induction calculation by MATLAB shows that when the diameter ratio d / D is 0.4 and the velocity is 9.76m/s, the electrostatic induced charge of dust particles is the largest at this time. It has certain guiding significance for the design of dust measurement pipeline.