bluuebunny/crossref_metadata_2025 huggingface dataset:
Functionals in stochastic thermodynamics: how to interpret stochastic integrals
Authors: Bo Stefano , Lim Soon Hoe , Eichhorn Ralf
Published: August 2019

In stochastic thermodynamics standard concepts from macroscopic thermodynamics, such as heat, work, and entropy production, are generalized to small fluctuating systems by defining them on a trajectory-wise level. In Langevin systems with continuous state-space such definitions involve stochastic integrals along system trajectories, whose specific values depend on the discretization rule used to evaluate them (i.e. the ‘interpretation’ of the noise terms in the integral). Via a systematic mathematical investigation of this apparent dilemma, we corroborate the widely used standard interpretation of heat- and work-like functionals as Stratonovich integrals. We furthermore recapitulate the anomalies that are known to occur for entropy production in the presence of temperature gradients.
Pyrolysis-GC/MS study of fast growing wood Macaranga gigantea
Authors: N Subagyono RR D J , Qi Y , Sanjaya A S , Amirta R , Chaffee A L
Published: August 2019

Py-GC/MS study on fast growing wood Macaranga gigantea at different temperatures has been conducted. The pyrolysis yields and chemical compounds obtained based on the pyrograms of the biomass by Py-GC analyses were compared with those obtained from batch pyrolysis experiments under similar conditions. Results show that the pyrolysis yields of Macaranga gigantea from Py-GC/MS analyses and batch reactor experiments at 300-450 °C were generally similar, ranging from 35 to 65%. Pyrolysis of the woody biomass with both techniques produced compounds which are mostly derived from pyrolysis, thermal degradation, or volatilization of lignin and cellulose/hemicellulose.
A review on photocatalytic: Modification of material and the application to removal of dye in wastewater
Authors: Wahyuniati R E , Hindryawati N , Wirawan T , Subagyono D J N , Panggabean A S
Published: August 2019

Photocatalytic materials have become a field of expansion in research, as evidenced by the many publication in science. With the many variation of semiconductors being tested as photocatalytic, it is necessary it with other materials or different semiconductor materials. Dealing with such an amount of information requires updated and educated guidance to select the most significant realizations. The state of the art photocatalysis with regard to materials and systems, considering the well-established results, but also the emerging aspect, and the envisaged new directions of this technology in the near future. In simulation and optimization of the photocatalytic reaktor model offer the last design. In addition, the opportunity for light source to be increase durability, relatively low cost and increase flexibility in the design and operation of future photocatalytic reactors.
Potential sulfate reducing bacteria for decrease Fe and Mn determination agents on ex-coal mining soil in Samarinda
Authors: Kusumawati Eko , Tri Widodo Nanang
Published: August 2019

The aim of this study was to determine the potential of sulfate reducing bacteria (SRB) as reducing agents for decrease Fe and Mn in acid soils of coal mines using five isolates of isolated SRB from post-coal mining sediments in Samarinda. The SRB potential test in reducing Fe and Mn was carried out by growing SRB on liquid Postgate media with varying pH of 3, 4 and 5 with the addition of mine acid soil to each treatment. Each of the pure SRB isolates (1 ml) was inoculated into liquid Postgate media with different pH, namely pH 3, 4 and 5 which had previously been filled with 5 grams of acidic soil after coal mining which had been mashed and sterilized at 121°C for 15 minutes. The culture was incubated in a threaded tube of 10 ml volume to full. The results showed that five isolates of SRB from post-coal mine sediments in Samarinda were Desulfococcus sp., Desulfotomaculum sp., Desulfobacter sp., Desulfobulbus sp. and Desulfobacterium sp. have potential as reducing agents for decrease Fe and Mn in Postgate B liquid media which have been added with coal mine acid soils. The best efficiency of Fe reduction by Desulfobacterium sp. at pH 3 is 6% and the best Mn reduction by bacteria Desulfotomaculum sp. at pH 5 is 4%.
Quorum quenching of Bacillus cereus INT1c against Pseudomonas syringae
Authors: Ananda Meryany , Rusmana I , Akhdiya A
Published: August 2019

Quorum Quenching is a process to prevent AHL signal accumulation resulting in the virulence factors and pathogenicity genes. The aims of this study were to determine the ability of the AHL (Acil Hocerine Lactone)-lactonase produced by Bacillus cereus INT1c and its potential as a biocontrol agent against Pseudomonas syringae. The experiments were swarming motility inhibition of P. syringae and inhibition assay of P. syringae on snap beans, INT1c produced extracellular and intracellular AHL-lactonase which could inactivate quorum sensing process of C. violaceum. The crude enzymes of INT1c were precipitated optimally at 70% saturation of ammonium sulphate. The Bacillus could reduce rot symptom of snap beans caused by P. syringae and motility of the pathogen. Swarming motility distance of the pathogen on control plates were 12.25 mm while the pathogen was co-cultured with INT1c was 3.3 mm. The average length of rot symptoms on positive control was longer (6.4 cm) than the snap beans inoculated with INT1c (3.92 cm). The population of P. syringae on the snap beans was decreased. Due to nutrient competition between P. syringae and INT1c. These results indicated that INT1c was potentially developed as a biocontrol agent.
Characterization of Phytophthora nicotianae fungi from Sulawesi cacao
Authors: Suwastika I N , Rifka  , Aisyah N , Rahmansyah  , Muslimin  , Ishizaki Y , Cruz A F , Basri Z , Shiina T
Published: August 2019

A pod rot disease caused by Phytophthora is one of serious treat on cacao farming system. This infection was reduced annual bean production remarkably (up to 30%). So far, there are seven species of this fungi were identified from the cacao farm over the world. However, we still lack of information on phytophthora properties from Sulawesi farm, which supplied more than 60% Indonesian cacao bean production annually. Here we report our result on isolation, identification, and characterization of these fungi from Sigi-Biromaru area (one of main farming area in Central Sulawesi). We showed that P. nicotianae could isolate from local infected pot. Bioassay on it infection rate was shown depend on the recictency of cacao clones/cultivars. This data suggesting that various species of Phytophthora exist in Sulawesi cacao farm, and its pathogenity was depend on the susceptibility of its clone of cacao.
Antioxidant activity of flavonoid constituents from the leaves of Macaranga tanarius
Authors: Marliana E , Ruga R , Hairani R , Tjahjandarie T S , Tanjung M
Published: August 2019

The beneficial health effect of natural flavonoids in plants is mainly because of their antioxidant properties. In the present study, antioxidant activity of isolated compounds from the leaves of Macaranga tanarius including nymphaeol C (1), solophenol D (2), nymphaeol A (3) and nymphaeol B (4) was conducted using 2,2-diphenyl-1-picrylhidrazyl (DPPH) method. The result showed that compound 2 revealed potential antioxidant activity followed by 1 and 4 with IC50 values of 55.13, 62.14 and 72.83 µM, respectively. While compound 3 showed antioxidant activity with IC50 value of 102.12 µM.
Antibacterial activity of flavan-3-ol derivative compound from dichloromethane extract of Artocarpus dasyphylla tree bark
Authors: Indriani Indriani , Harso Wahyu , Sosidi Husain
Published: August 2019

Infectious disease is one of sources of high morbidity and mortality caused by bacteria. Artocarpus plant is biosource to discover compounds with interesting bioactivites. The objective of this study is to find antibacterial compound from nature by extraction, fractionation, identification, and antibacterial test of secondary metabolite from dichloromethane extract of Artocarpus dasyphylla tree bark. The dichloromethane extract was fractionated repeatedly using various chromatographic techniques. The secondary metabolite was identified of its molecular structure based on UV-Vis, IR, NMR spectral data and confirmed by comparation with the reference. The secondary metabolite was known as catechin or 5,7,3’,4’-tetrahydroxyflavan-3β-ol. Antibacterial testing of cathecin against Escherechia coli and Staphylococcus aureus showed a low antibacterial activity.
Oil palm fruit ripeness detection using K-Nearest neighbour
Authors: Astuti I F , Nuryanto F D , Widagdo P P , Cahyadi D
Published: August 2019

Palm oil plant (Elaeis guineensis jacq) is one of the most popular plants in Indonesian plantation and also a species of the palm family. Harvesting process should obtain fresh fruit bunches at optimal ripeness. Some farmers are lack of ripeness knowledge and do not understand which color that represents optimal ripeness of palm fruit to harvest. Another issue on the scarcity of such system provides ripeness identification also encourage a study to develop an image-processing-based expert system. The aim of this study is to provide a tool for examining oil palm fruit ripeness level. Identification system consists of several image processing phases, namely image edge detection and feature value of the image to be calculated such as mean value, standard deviation, skewness, entropy, energy, homogeneity, contrast and intensity. In the proposed work, K-Nearest Neighbor (KNN) is applied as a computation method which allows the system to classify data of ripeness level based on user-entered image. The output is the identification of the ripeness level of the oil palm fruit.
Environmental quality index modeling in Indonesia using ordinal probit regression approach for panel data with random effect
Authors: Suliyanto
Published: August 2019

Environmental issues are one of the important global issues and are of concern because they are considered to require a solution. The Ministry of Environment and Forestry has developed an Environment Quality Index (EQI) that provides rapid information of an environmental condition with river water quality, air quality, and forest as indicator. This study aims to model EQI in Indonesia using ordinal probit regression for panel data with random effects. Parameter estimation of ordinal probit regression model for panel data with random effect using the marginal likelihood function, and maximize that function using M-point Gauss-Hermite Quadrature method. The data that be used in this study is EQI from 33 Provinces in Indonesia during 2011 to 2016 which are categorized into three category i.e less good, good and very good. The result of modelling is gotten variable that influence to EQI is Human Development Index (HDI). EQI opportunities in DKI Jakarta province in the year 2016 in the category of less good is high enough, that is equal to 99.89%. This may be due to high population density and less balanced with awareness of the population to preserve the environment. The accuracy of classification of modeling result is 70.202%.
Parameter estimation of mixed geographically weighted weibull regression model
Authors: Suyitno  , Sari N W W
Published: August 2019

This study discusses a Mixed Geographically Weighted Weibull Regression (MGWWR) Model. MGWWR is a regression model developed from a Geographically Weighted Weibull Regression (GWWR) model. Parameter estimation of GWWR model is done locally at every observation location using geographical location weighting. Based on parameter identification result in GWWR model, the certain covariates influencing the GWWR model may be global (the same value) in nature, whist others are different. Based on consideration this situation, a MGWWR model is proposed, in which some parameters are assumed to be constant and the others are different for every local model in the study area. The aim of this study is to identify the constant and local parameters in GWWR model, and to estimate the MGWWR model parameters using maximum likelihood estimation (MLE) method. Identification of constant and local parameters in GWWR model is initial step to construct the MGWWR model. The results show that test statistic for hypothesis testing on the constant parameter identification is Wilk’s statistic derived from likelihood ratio test (LRT) method, and the maximum likelihood estimator of MGWWR model can be obtained by using the Newton-Raphson iterative method based on the back-fitting procedure.
Forecasting index and stock returns by considering the effect of Indonesia pre-presidential election 2019 using ARIMAX and VARX approches
Authors: Ulyah S M
Published: August 2019

Election is a national event that can create significant impact on many sectors in a country. One of the affected sectors is finance. The upcoming Presidential election in Indonesia has two strong candidates who are rival since the late presidential election in 2014. The effect of this election is expected to have a big influence in the capital market, especially for Indonesian Index (IDX composite). Moreover, the stock owned by the candidate or the candidate relative is also expected to behave unusual. Therefore, this study aims to predict the return of those stock and index with the influence of Indonesia Pre-Presidential Election 2019. The stock of interest is the stock of PT. Saratoga Investama Sedaya Tbk (SRTG). The method used in study is defined into two categories. The index and stock are analyzed individually by univariate method—Autoregressive Integrated Moving Average with Exogenous variable. Multivariate method is also conducted to examine the relation among these stock and index. The used approach is Vector Autoregressive with Exogenous variable. The exogenous variable in this study is the dummy variable of Indonesia pre-Presidential Election. The results show that pre-election vibe does not significantly affect the return of the index and stock.
The impact of teaching style and FCI gain on the performance in mechanics tests
Authors: Azzopardi C , Camilleri L , Bonello C
Published: August 2019

The purpose of this study is to identify the relationship, if any, between the gain in the force concept inventory (FCI) and study level, gender, repeaters/non-repeaters, teaching style and the end-of-year mechanics result. The study focussed on all students (N = 395) admitted to a post-secondary institution in Malta in October 2015 and who participated in the pretest and posttest FCI exercise, studying physics at advanced (N = 162) or intermediate level (N = 233). There were 36 students at advanced level and 44 students at intermediate level who did not participate in the posttest FCI. In this study a multiple-choice test was used comprising of 30 questions about mechanics concepts and a questionnaire (by Centre for Occupational Research and Development (CORD)) was given to the lecturers to identify the teaching goals and methods used. The pretest was given on the second week of the academic year, October 2015, so that their response was not influenced by mechanics teaching and the posttest (identical to pretest) was given in the end of the scholastic year, May 2016. The results of the study suggest that only 13.7% of the participants exceeded the average-expected gain of 24%. The gain is higher for males, for participants studying advanced level physics and for participants who were taught by particular lecturers with particular teaching goals and methods. There is a positive correlation between the gain in the FCI and the end-of-year score in mechanics questions about forces and Newton’s laws of motion.
Using students’ learning to improve teaching: the case of the cream rising to the top
Authors: Borg Marks Joan
Published: August 2019

Teachers go to class to teach their students. One may question how often teachers use students’ visualisation of a concept to probe students’ understanding and to improve their own teaching. This paper focuses on the link between analogical reasoning and mental modelling in the teaching of electric circuits. A study conducted with 17-year-old physics students of different ability is described. From the results of a pre-test, post-test and semi-structured interviews using an ‘analogy prompt’, it will be shown how, when learning is meaningful, analogy generation can be developed and modified easily by students to relate the analogue to the target in question, thus providing evidence of the existence of scientific models of concepts in the minds of the students. It will be argued that the teaching of abstract concepts may be improved by using analogies indicated by high ability/gifted students who manage to develop a scientific view of concepts in question.
3D-printable height models for dc circuits
Authors: Bodensiek O , Sonntag D A , Glawe I , Müller R
Published: August 2019

We present an approach to learn about electricity and dc electric circuits by using real representational models based on the gravitational analogy. The additively manufactured models are deployed in a small-scale teaching intervention on electric potential and voltage in simple electric circuits. From the preliminary results considerable learning gains can be inferred.
Learning how to teach experiments in the school physics laboratory
Authors: Gkioka O
Published: August 2019

The focus of this research is in the broader area of physics teacher education. The aim is to investigate physics teachers’ efforts to learn how to teach and assess experiments, and in particular, concepts related to scientific evidence in the school physics laboratory. The study has looked at the participants as both learners and prospective teachers. It has taken place within the context of the course “Secondary Science Lab Applications” within a pre-service teacher education program in a Department of Secondary Science and Mathematics Education. Twenty-four students participated. The participants: a) revised the main concepts related to scientific practices (in particular, experimental validity and reliability of measurement), b) developed lesson plans, teaching and assessment methods and, c) taught school physics experiments. Interviews were conducted with the participants during their preparation for teaching and after teaching. They were observed when teaching and all classes were videotaped. A qualitative and quantitative data analysis identified particular trends among the participants. Students’ difficulties while they designed, carried out experiments and wrote lab reports were identified, as well as the difficulties they experienced when teaching experiments.
Active-learning settings and physics lectures: a performance analysis
Authors: Schiltz G , Feldman G , Vaterlaus A
Published: August 2019

We have divided a non-physics undergraduate student cohort into two parallel teaching settings. We offered a highly interactive flipped class (SCALE-UP) to one group of 52 students and a reformed LECTURE to the remaining 318 students. We compared student performance in both settings, based on a common midterm exam. The SCALE-UP students performed significantly better on conceptual problems, but for numerical problems, SCALE-UP and LECTURE students showed similar results.
Magnetic phenomena and living systems in the bio area degrees
Authors: Caltun O , Michelini M , Stefanel A
Published: August 2019

An educational path was designed aiming to improve the comprehension of basic concepts of magnetism of students of the Bio areas and developing a functional understanding of these concepts applied in the specific context of study and their work profession. A pilot study at the University of Udine involved students of agro-food degrees to analyse how they considered magnetic concepts and their use in their own area of study. In the final examination, they were requested to exemplify and to discuss in which contexts of their own area of study magnetic phenomena are involved. The students identified a wide spectrum of contexts in which magnetic concepts can be actualized at four different scales: astronomical/planetary, human/animal, cellular and atomic/nuclear. In the majority of cases, they showed competencies in using concepts like magnetic field and interaction to discuss in context examples in their own areas of study. Some difficulties in distinguishing magnetic effects from electrostatic effects emerged, as well as the need to be conscious of the strength, complexity and role of magnetic phenomena involving different scale levels at the same time.
The knowledge of Hungarian students in the light of the Mechanics Baseline Test
Authors: Kádár C , Tasnádi P
Published: August 2019

In the introductory courses in physics at Loránd Eötvös University (ELTE) students with very different physics knowledge can be found. The core problem appears to be undeveloped thinking skills and deficiency in conceptual understanding. Investigation of conceptual understanding is not simple, however, there are some reliable instruments for it such as the Mechanics Baseline Test which was constructed by Hestenes and Wells. In this paper the results of this test obtained in Hungary (mainly at ELTE) are presented. The test is universal in the sense that it is limited to the concepts that should be addressed in introductory physics at any level from secondary schools to universities. In 2016 at the Faculty of Science of ELTE students enrolled in introductory physics courses were tested. The students’ majors were Biology, Earth Sciences, Physics and Physics Teaching. The same test was given as a post test for the students of Physics and Earth Sciences. The results were compared to those of obtained previously in Hungarian secondary schools, at ELTE courses and at the universities in the USA (Arizona State University, Harvard University). It can be stated that at ELTE the test scores of the students of physics major has decreased significantly in the last 20 years. (Maybe it is the consequence of the implementation of Bologna Process due to which the number of the students entering into the University highly increased.) It was also revealed that there are difficult topics in kinematics and dynamics the understanding of which shows serious deficiencies at any level. (For example the dynamics of the curvilinear motion.) Finally on the basis of the results a proposal for the improvement of the instruction strategy is presented.
Boat in the pool – lab work
Authors: Dvořáková I
Published: August 2019

This article describes a non-traditional lab focused on applying Archimedes’ principle in a situation that is, for students, new and unusual. Two main interconnected features of this lab are important. Firstly, it is not a “standard” lab experiment in which students are instructed to measure something and then to interpret results. Here, a very important element is prediction. Students have to predict the result first, calculate it using Archimedes’ principle, and only then do the measurement. Secondly, it is not the teacher who tells students whether their calculation is right or wrong, it is the experiment itself. This article presents the lab work itself (instructions and results), some methodological comments, and my experience in school.
Experiments and representations in quantum physics: teaching module on the photoelectric effect and the Franck-Hertz experiment
Authors: Ravaioli G
Published: August 2019

A teaching module, centered on the photoelectric effect and the Franck-Hertz experiment, was designed for upper secondary school students. The activities have been built upon three design principles, brought out from an analysis of the current research literature about laboratories, learning/teaching quantum physics and representations in physics education.
Meaningful student involvement. Students as “researchers”: a physics laboratory experience from space to microworld
Authors: Bertelli S , Centioni R , Scerbo F
Published: August 2019

Teaching physics and technology is a challenging, rewarding and exciting arena where teachers share the fascinating concepts of physics and technology evolution in a room full of young and inquisitive minds. Every day teaching experience confirms that Science learning motivation is correlated to real world applications. According to the last PISA-OECD survey, the performance of Italian students in STEM is below the OECD average. In the last years the Italian Ministry of Education, University and Research (MIUR) has been active in promoting a wide plan to improve STEM learning. These actions strongly supported the connections and collaborations between high schools, universities and research centers. In this framework, the Frascati National Laboratories (LNF) play a very important role in science dissemination through a rich program of physics education activities addressed to Italian teachers and students from all the world. The main idea is that meaningful involvement of students can take the form of engaging students as researchers. In this article the LNF activities for schools are presented with a focus on a case study of a work-related learning program attended by seventeen students of the high school “Liceo Siciliani” from Catanzaro (Italy) in February/March 2017. The students had the possibility to participate in two different experiences related to particle physics and nanotechnology. The project concerning particle physics will have a follow up, since the school “Liceo Siciliani” proposed an experiment on cosmic rays that will take place in the Calabria region, based on the experimental setup the students studied and used at LNF.
Using a large amplitude pendulum in a learning cycle strategy
Authors: González y Hernández A
Published: August 2019

Experiments with a damped simple pendulum were carried out and modelled for large amplitude motion with physics students in a mechanics laboratory course of the first year of the university. The equation of motion used for this pendulum was the equation of a damped pendulum where the simplification for small angles was avoided. In this investigation, the damping of this pendulum was assumed to be proportional and opposite to its velocity. This hypothesis was verified experimentally and the constant of damping was measured from the experimental data. This constant was introduced in the equation of motion of the pendulum to be solved by a numerical method. The comparison made between the numerical solution and experimental data was successful, giving students confidence in the strategy followed. With the support of the teacher students modelled empirically the period of the pendulum as a quadratic function of its amplitude and made good predictions of the behavior of the pendulum for other amplitudes by using the numerical solution. On completion of the course, in a revision of the students’ reports, it was possible to propose an empirical equation as an analytical solution for this pendulum, an important result of the learning cycle carried out in the study of the pendulum. In this process of teaching, students developed scientific skills that were evaluated and both students and teachers were able to build new knowledge about a pendulum with large amplitude.
Metaphors and analogies proposed by perspective primary teachers to support the exploration of magnetic phenomena.
Authors: Bozzo G , Daffara C , Michelini M , Monti F , Vercellati S
Published: August 2019

Analogies and Metaphors play an important role in primary science education to correlate abstract aspects and lived experiences, providing concrete meanings for pupils. They represent important educational tools that can help young pupils to approach towards abstract physics concepts like those related to magnetic phenomena. The significant presence of these phenomena in the world of 21th century allows pupils to explore and to familiarize with them starting from their childhood. These daily experiences offer pupils the opportunity to build spontaneously their own interpretative models about magnetic phenomena that influence also their future learning processes during the school careers. Recent educational researches have shown how pupils are able to master the interpretation of magnetic phenomena if those aspects are activated in the context of Conceptual Laboratories of Operative Exploration (CLOE). In order to improve the competencies of Prospective Primary Teacher (PPT) students related to the use of analogies and metaphors in education, a specific module of formative intervention was developed and proposed involving 92 PPT students enrolled at the University of Udine and 67 PPT students at the University of Verona. Initially, an overview of a well-experimented learning path was proposed to the involved PPT students and then they had the opportunity to try experimentally the proposed activities. After that, they discussed in small groups how to face magnetic phenomena with primary pupils with the use of analogies and metaphors. Finally, each PPT student was asked to produce an individual proposal that was shared within the small groups, commented and, finally, individually revised. In this paper, we present a preliminary analysis of the analogies and metaphors through which PPT students would introduce the magnetic phenomena observed in the GEI exhibition to primary school pupils.
Quebec children and elementary pre-service teacher’s conceptions of force and motion
Authors: Métioui A , Trudel L
Published: August 2019

The analysis of the data of the paper questionnaire that we distributed to fifty-eight (58) children and 85 pre-service teachers of elementary education from Quebec in Canada demonstrates that most of their conceptions of force and motion are incompatible with established scientific theory. They look like those developed in the setting of the pre-Newtonians Physics such as the Aristotelian view and the 14th-century Impetus theory by Buridan. Most of the misconceptions identified are: the movement requires the continuous application of force; in the absence of a force, the objects are to be at rest; if an object is not moving, there is no force acting on it. The results were analyzed in the light of previous research on students’ conceptions of motion and force.
The Augmented Laboratory – 3D, Multiple Object Tracking
Authors: Rosi T , Onorato P , Oss S
Published: August 2019

We discuss the three dimensional, multiple object tracking capabilities of the “Augmented Laboratory”, a custom hardware and software setup we created for this purpose. Overall it proves to be a powerful and useful educational tool, not only allowing to use tracking in many more experiments with respect to traditional video tracking, but also creating 3D visualizations of the experiments themselves and of the tracking results. The setup was also tested with a group of aspiring teachers and their comments were here discussed.
Three years evaluation of a teaching learning sequence on rolling motion based on a blended learning environment
Authors: Onorato P , Malgieri M , De Ambrosis A
Published: August 2019

As highlighted by research, students have difficulty in understanding the physics of rolling motion and the role that sliding friction forces have in it. Physics courses at high school and introductory university level do not usually handle the subject with the attention it deserves. Textbooks often only show particular rolling examples instead of providing a general treatment of the underlying physics. Therefore, students can develop misunderstandings that lead to errors when approaching general problems. In 2014 we have designed a teaching learning sequence (TLS) rooted in previous research about student conceptions, centred on the role of friction in different cases of rolling. A series of experiments based on video analysis integrated with interactive simulations were used to emphasize key concepts and to motivate students in their exploration of the subject. The activity sequence was designed for undergraduate students or advanced high school classes. In this paper we report novel results from three years of testing and refining the teaching sequence at both the Universities of Pavia and Trento.
The time in science: an interdisciplinary laboratorial approach
Authors: Montalbano V , Castellini A , Donati A , Marchini D , Mariotti E , Mariotti M A , Porri A , Rossi B , Severi A , Sirigu M , Veronesi S
Published: August 2019

In order to promote problem-based and active learning in the physics laboratory, we designed a flipped classroom focused on the Franck-Hertz experiment. The flipped classroom approach moves course content from the classroom to homework and uses class time for engaging activities and problem solving. This constructivist approach to teaching is an effective means of student-centred collaboration and it can promote active learning, enhance critical thinking and obtain the maximum use of student-faculty time together. We report preliminary results of the flipped classroom approach to a laboratory and how it worked in the context of a small group of students in a physics course.
Assessment of problem solving activity on wave physics in secondary school
Authors: Minozzi F , Marzoli I
Published: August 2019

Italian secondary school students struggle with understanding wave-like phenomena. Many research-based materials are available on the topic, but their applicability is often limited by the constraints of actual school settings. We developed a set of conceptual problems on wave phenomena and tested them in classroom within a design-based research framework. We present the preliminary results of an on-going work that aims at providing teachers with high-quality versatile materials, along with testing our hypotheses on the learning processes.
Training teachers to use playgrounds in physics teaching
Authors: Pendrill A-M
Published: August 2019

Climbing racks, carousels, swings and slides can be used for many experiments and demonstrations that offer suprising results, often challenging students’ understanding of motion. This paper describes activities used in professional development workshops for teachers on the use of playgrounds in physics teaching. Toys and other simple equipment complement the experience of the body. In addition, smartphones can be used both for documentation and measurements. The activities emphasize how playground experiments can connect very concrete experiences of acceleration and force to textbook examples and fundamental physical principles.
Wondering with physics: engage public and teachers in science communication
Authors: Montalbano V , D’Onghia A M , Giambolini M , Montorzi R , Rossi B , Sirigu M
Published: August 2019

The European Researchers’ Night takes place every year simultaneously in many cities all over Europe and beyond. Researchers and teachers designed and implemented together a series of inquiry-based activities to bring people closer to physics. The enthusiast answer from participants suggests that these activities can be easily utilized with students for enhance their motivation. Moreover, the close collaboration between university and secondary school teachers is an opportunity for promoting the professional development on topics, like resonance or birefringence, sometimes very far from teaching practice.
Research on Influence of Converter Transformer Grouping and Receiving End Power Grid Structure on Converter Transformer DC bias
Authors: Ma Chenglian , Sun Li , Zhao Shujian , Liu Lianguang
Published: August 2019

When ±800kV UHVDC project was put into operation, DC bias problem can not be ignored. In this paper, a calculation model for DC bias current is established based on Xiluodu-Zhexi UHVDC project data. Converter transformer grouping and receiving end power grid structure are considered. The converter transformer DC bias current is calculated by node voltage method. The influence of different converter transformer grouping modes, distance between grounding electrode and substation, and the feeder length and the number of feeder loop are analysed. The results show that, single-phase converter transformer bias current is maximum with full load and 6 converter transformers under 1/2 monopole earth mode. And bias current level of converter can be reduced in planning and designing.
Research on the Method of Reducing Transformer DCBC Considering Converter Transformer Grouping and Receiving End Power Grid Structure
Authors: Ma Chenglian , Sun Li , Zhao Shujian , Liu Lianguang
Published: August 2019

Based on the study of the influence of converter marshalling and receiving grid structure on the DC bias current (DCBC), DCBC levels of typical connection structures between converter station and its adjacent substations is analysed in this paper. Then DCBC levels of converter stations and AC substations under different connection modes of substations in AC power network are analysed. The measures to reduce DCBC of converter transformer and AC transformer considering various factors are put forward. A method to reduce DCBC of converter transformer and transformer considering converter transformer grouping and receiving end power grid structure is proposed. The measures of restraining DCBC are analysed from the aspects of operation mode selection, grounding pole location, power grid structure planning and design. Suggestions are put forward for the treatment of DCBC in the planning and design stage.
Analysis of Reactive Power Demand Based on Voltage-Reactive Power Correlation
Authors: Hu Zhen , Zuo Jian , Chen Daojun , Cui Ting , Wang Ding
Published: August 2019

The inaccuracy of reactive power demand analysis in practical power system often leads to the problem of low voltage stability margin. In this paper, the analysis method of voltage-reactive power correlation is proposed, which is used to solve the inaccuracy of reactive power demand analysis. The proposed method can quickly analyze the reactive power demand of each region only according to the voltage stability margin index. The local reactive power compensation and the input reactive power on the system side are considered in the derivation of the voltage stability margin. Therefore, the proposed method accords with the practice of power system. The effectiveness of the proposed method is proved by a simple system.
Bias-dependent Access Resistances Extraction in 0.15 µm GaAs pHEMTs
Authors: Dang Ruirui , Yang Lijie , Song Chunyi , Xu Zhi Wei
Published: August 2019

Devices’ performance analysis and successful circuit design strongly depend on accurate large signal models. This, in turn, requires accurate small signal models. However, the reliable parasitic parameter extraction of GaAs pHEMT greatly influences the accuracy of small signal models, which also greatly influences the extraction of intrinsic elements. The access parasitic source and drain resistances, Rs
and Rd
, are associated with gate bias due to the two-dimensional charge control. In this work, we directly extract Rs
and Rd
from S-parameter measurements of the device under test (DUT) under strong inversion operating biases. The proposed method has been validated by simulation and on-wafer measurements. It shows better accuracy than existing arts in a frequency range of 0.5–40 GHz (0.5 GHz step). Furthermore, a 10-15 GHz GaAs pHEMT power amplifier (PA) is employed to further validate the developed method. The test results also validate the developed method.
Optimal Charging and Discharging Control of Plug-in Hybrid Electric Vehicles in a System-level Power Distribution Network
Authors: Li W , Lin Z Y , Yan G F
Published: August 2019

With the increasing popularity of plug-in hybrid electric vehicles (PHEVs), coordinated charging and discharging of PHEVs has become an important issue in power distribution networks. To this end, we employ a multi-objective optimization model to formulate the problem of coordinated charging and discharging of PHEVs, in which the objectives of load shifting and total costs minimization are both investigated under system’s technical constraints. A hierarchical optimal algorithm combining the iterative water-filling-based algorithm and the consensus-based method is proposed to solve the multi-objective optimization problem. It shows that the proposed algorithm not only enhances stable performance for the power load but also guarantees low-cost satisfaction for the vehicle owners in the system-level power distribution network integrating physical power network with information network together. Numerical simulations are presented to demonstrate the effectiveness of the proposed algorithm.
Harnessing of Wave Energy using Axially Magnetized Linear Generator with Data Logger using Gizduino Microcontroller
Authors: Cruz K , Dator F , Ong J , Bumanlag N , Pacis M C
Published: August 2019

This study focused on the design and construction of wave energy generation system. Wave energy is produced once the electric generators is placed parallel on the ocean surface and rides in different height of waves along the length of the device. It follows the concept of Faraday’s law of induction in the linear generator which an alternating current is induced in the loops of copper wire whenever the magnet slides back and forth through it. Using Axially magnetic type linear generator that will utilized the horizontal forces brought by the waves and placed on a waterproof floating boat with a data logger using microcontroller. The wave converter is deployed in a controlled and uncontrolled environment to observe the behaviour of the prototype and compared the measured parameters such as voltage, current, power, and energy at different time and wave height.
Optimized Algorithm for Muscular Diseases Recognition Based On Temporal Parameters Analysis and Correlation Coefficients
Authors: Mejia-Gonzalez E.A. , Lopez-Leyva J.A. , Estrada-Lechuga J. , Ponce-Camacho M.A.
Published: August 2019

In this paper, an optimized algorithm based on temporal parameters analysis and correlation coefficients is presented in order to perform muscular diseases recognition. Statistical information was measured of three classes signals (Healthy, Myopathy and Neuropathy conditions). The temporal parameters that were initially proposed (14) were optimized based on the correlation coefficients. Thus, only 9 parameters were selected for optimized the algorithm, and the time required for training and recognition is ≈ 0.2s and ≈ 4ms, respectively.
On Active and Reactive Power Control of Synchronous Generators: A Port-Hamiltonian Approach
Authors: Tajik Elham , Runolfsson Thordur
Published: August 2019

In this paper a general port-Hamiltonian model of a synchronous generator is presented and the effects of deviations and disturbances of the terminal signals on generator control laws are discussed. We discuss how control laws should be designed to minimize the effect of small variations in the generators terminal conditions, i.e. local control that does not have access or knowledge to a model of the rest of the system. For analysis purpose we present a linearized generator model and apply a full state feedback control consisting of both regulation of the generator flux and rotational dynamics.
Applying Selected Lost Circulation Materials to Study Lost Circulation of Azkand Formation in Khabaz Oil Field
Authors: Shibeeb Mazin J. , Alwasiti Asawer A. , Al_Zubaidi Nada S.
Published: August 2019

Managing lost circulation during drilling is a great challenge issue in naturally fractured or vugy formations. This situation becomes further complicated if there are gas or oil returns at the same formation or at a formation above it. The lost circulation problem happens in some of the northern Iraqi oil fields such as Khabaz oil field. Particulate lost circulation materials (LCM) have been used for many years to control lost circulation. However, these traditional LCMs are not efficiently applicable to cure sever to total losses, such as highly fractured formations and formation with large vugs. In this work, an experimental attempt was done to solve such problem in Khabaz oil field. The experiments were carried out using a closed loop circulation system that simulates the drilling fluid loss into formations. Five core plugs from Azkand formation of Khabaz oil field from different depths were used. The experiments were grouped into three, the first was done with the fresh-water-based drilling fluid to measure the severity of losses. The second, fresh-water-based drilling fluid was treated with traditional LCM (cotton seeds) to investigate how the severity of losses is affected by these materials. Adding polymer lost circulation material were the last sets to modify the drilling fluid rheological properties which prepare a medium within the lost circulation zone that increases the friction inside the losses paths to increase the LCMs (the polymer itself) sealing efficiency.
Activation Iraqi bentonite for using as drilling mud
Authors: Ibrahim A S , Al-Bidry M A
Published: August 2019

Drilling fluid is very important in drilling a well because it plays a vital role in all drilling operations. Drilling fluid should have popular properties that simplify safe and easy completion of the well. Because of the big cost of transporting and imported clays that used as drilling fluid, Iraqi benronite must be enhanced to use as drilling fluids due to its poor rheological and filtration properties, and stability. Iraqi bentonite has a limited usage in oil field because it is Ca- bentonite. The research has studied the usage of bentonite and its activation by NaoH in drilling fluid. The results show that Iraqi Ca-bentonite reaches to API specifications while the indirect activation includes activated Ca-bentonite by NaOH with different concentrations, HCL then NaOH without temperature and HCL then NaOH with temperature. Then activated bentonite is used as drilling mud. The results show that the indirect activated bentonite does not reach API specification, where XRF analysis show that an ion exchange between Ca and Na is not enough to convert Ca- bentonite to Na- bentonite.
Better Hole Cleaning In Highly Deviated Wellbores
Authors: Allawi Raed H. , Almahdawi Faleh H. M.
Published: August 2019

Many drilling problems (lost circulation, hurdle in running casing, poor cement jobs, high torque and drag and the necessity of re-drilling and, mechanical stuck caused by cutting accumulation in the wellbore) can be avoided by good hole cleaning during drilling operation especially in directional wells.

In this experimental work, the cutting transport ratio (CTR) in hole inclined (60 degree) from vertical was estimated by using three values of drilling mud viscosities, three annular velocities, two types of cuttings size and two rotation speed of inner pipe (RPM). Note that the rig consisted from PVC outer casing 4 1/2 inch as OD diameter and inner drill pipe 2 inch as OD diameter.

The experimental results showed that the Cuttings Transport Ratio (CTR) increased with increasing the annular velocity and better hole cleaning which obtained from the third velocity (3.247 ft/sec) for all cases. Moreover, increasing the mud yield point (YP) helped to improve the cuttings transport ratio; however increasing the mud yield point slightly affected with increased the annular velocity. Furthermore, it was noticed that the rotation of drill pipe (RPM) is one of the most important parameter for cuttings removal especially in laminar flow and transition flow. The cuttings sizes 1.7 mm are also easier to transport than 3.35 mm cuttings sizes for all cases except low yield point (YP).