bluuebunny/crossref_metadata_2025 huggingface dataset:
Learning trajectory for teaching number patterns using RME approach in junior high schools
Authors: Fauzan A , Diana F
Published: March 2020

This research aimed at developing a learning trajectory based on realistic mathematics education (RME) approach, for teaching number patterns to the students at grade eight junior high schools. The research employed design research approach proposed by Gravemeijer and Cobb. The activities of the research consisted of a cyclic process of preparing for the experiment, conducting the experiment, and retrospective analysis. The learning trajectory for teaching number patterns was designed during preparing for the experiment phase, and then it was validated by three math educators. It was tried out in a small group, followed by try out in a regular classroom during conducting the experiment phase. Retrospective analysis was conducted after each try out to improve the learning trajectory. 32 grade eight students of a junior high school in Padang were involved as the subjects of the research. Data were collected through observations, analyzing students’ works, videotaping, and test. Collected data were analyzed descriptively. Through this research we developed a RME-based learning trajectory for teaching number patterns. The learning trajectory reached the criteria of content and construct validity; reflected the state of the art RME, internally consistent, and potential to develop students’ reasoning. It also satisfied the criteria of practicality in which the learning trajectory worked as intended in the classrooms. The results of students’ works showed that the learning trajectory could also improve the students’ reasoning in learning number patterns.
The implementation of STEM approach in teaching electricity and statistics to a group of ix grade junior high school students in Yogyakarta
Authors: Novi Kurniati Yustina , Doris Sri Rejeki Cicilia , Sarkim Tarsisius
Published: March 2020

Youth Manual (2016) predicted the increase of Science, Technology, Engineering and Mathematics (STEM) -related jobs in the next five years. One of the characteristics of these jobs is it’s require capability to think and work interdisciplinary. STEM approach can be seen as a teaching approach that ask teachers to view Science, Technology, Engineering and Mathematics as an interrelated discipline and to teach the topics within the areas by using integrative and thematic approach and teach them based on a real phenomenon. This research was aiming at trying out the implementation of STEM approach to teach the topics of electricity in Science and Statistics in Mathematics to grade IX students by using real life phenomena and to measure students’ learning results. The research implemented Design Research method. Data were collected by observation and test on students’ understanding of the subjects. The data was analyzed quantitatively. The results demonstrate that the students’ mastery on the subjects was good and excellent. This research suggested that STEM approach has a potential to be implemented in Indonesian Junior
Learning the relation between quadrilateral using geometry’s puzzle for blind students
Authors: Andriyani  , Juniati D
Published: March 2020

Geometry is one of the fields in mathematics that deals with the shape, size, and properties of space that doesn’t require prior skills like basic arithmetic. Although the model of geometry’s object familiar and found in everyday life, it doesn’t mean that geometry is easily learned by students, especially to blind students who have limited visualization. A quadrilateral is a geometry matter which in its learning is often emphasized in the use of formulas and memorization so that students don’t understand the concept of each shape and its relation with the other ones. So, this underlies the researcher to design a learning trajectory of the relation between quadrilateral using geometry’s puzzle based on direct experience of blind students. The purpose of this research was determining the role of learning the relation between quadrilaterals using geometry’s puzzle to help students understand learning quadrilateral concepts. The method used is design research with Gravemeijer and Cobb’s model that through three stages, i.e. preliminary design, teaching experiments, and retrospective analysis. This research describes how geometry’s puzzle in learning the relation between quadrilaterals contribute to the understanding of quadrilateral concepts for blind students of MTs Yaketunis Yogyakarta. The result of this research shows that geometry’s puzzles can help increase students’ understand the concept of each quadrilateral shapes through the construction of knowledge about the relation between quadrilaterals so that students don’t need to memorize the definitions or properties of each quadrilateral shapes and achieve the defined minimum completeness criteria, that is 70.
Students’ ability to simplify the concept of function through realistic mathematics learning with the ethnomathematics approach
Authors: Herawaty Dewi , Widada Wahyu , Adhitya Alif , Sari Rosalia D W , Novianita Liza , Falaq Dwi Anggoro Abdurrobbil
Published: March 2020

The concept of function was a basic concept that students must understand in mathematics learning. This concept needs to be implicated through realistic mathematical learning with the ethnomathematics approach. The purpose of this study was to describe students’ ability to simplify the concept of function through realistic mathematical learning with the ethnomathematics approach. This was part of the research development. This stage was the prototype phase. We apply realistic mathematics learning with the ethnomathematics approach. The instrument of this research was the assignment sheet and the in-depth interview sheet by the researcher. Data was collected through task-based interviews. It was analyzed qualitatively. The results of this study were that students were able to simplify the concept of function through realistic problems based on “andun dance” culture. He simplifies the concept of mapping. For example, f was a function from set A to B, students were able to simplify the concept of function f with Df = A (domain function f was A). Also, being able to explain with various real examples and being able to show the position of the concept of function in a deductive structure of mathematics. The conclusion of this study was that realistic mathematics learning with ethnomathematics approach can be a vehicle for students to simplify the concept of function to be more meaningful.
Students’ thinking process in solving mathematical literacy problem with space and shape content
Authors: Lestariningsih  , Nurhayati E , Lutfianto M
Published: March 2020

Thinking process is one of the important activities in solving mathematical literacy problem. Thus, this paper aimed to identify two students’ thinking process in solving mathematical literacy problem with space and shape content. This study used descriptive research with a qualitative approach. Research subjects in this study were two tenth grade students of middle school. Data were collected by giving the mathematical literacy problem with space and shape contents and using think aloud. Next, data were analysed by studying the three types of thinking processes: conceptual, semi conceptual, and computational. The results of this study pointed out that the students’ thinking process were conceptual and computational. The activities carried out by students could be grouped into four categories, namely 1) stating what is known in the problem with their own language or changing in mathematical sentences, 2) stating what is asked in a problem with their own language or changing in mathematical sentences, 3) making a plan to solve problem completely, and 4) stating the steps taken in solving the problem using the concepts that have been studied. The type of thinking process of students influences the activities carried out by students in solving mathematical literacy problem so that teachers were supposed to consider this aspect when teaching mathematics especially topics that related to mathematical literacy.
Android application development of exploration career based on Multiple Intellegence: A model hypothetical
Authors: Bhakti C P , Rahman F A
Published: March 2020

The purpose of this study is to develop and design an android application of exploration career based on multiple intelligence that is used for high school students to provide information exploration career based on multiple intelligence. Data collection is done to find out the problems faced and to design solutions. The techniques for collecting data through literature studies. Exploration career based on multiple intelligence itself is a form of individual effort to find, obtain and manage various kinds of appropriate career information based on consideration of the intelligence possessed by each individual. Intelligence is the ability possessed by someone who includes knowledge, skills and expertise in solving problems. Basically, each individual is unique and has some intelligence such as linguistic, logical-mathematical, visual-spatial, kinaesthetic, interpersonal, intrapersonal, musical, and naturalist intelligence. By understanding that each individual is born and has different types of intelligence, here the author is interested in developing an android application about exploration of careers based on multiple intelligence-. This android application will provide an interesting description and design while at the same time helping individuals, especially high school students, in understanding the intelligence they have with the right career for their future, so it is expected that the development of this android application can provide a good understanding to each individual especially in understanding their career in accordance with their intelligence.
Application of “what-if” learning strategy to improve students’ mathematical critical thinking skills in statistical method I subject
Authors: Payadnya I P A A , Atmaja I M D
Published: March 2020

The aim of this study was to improve students’ mathematical critical thinking skills through the application of “What-If” learning strategies. This research was motivated by the lack of critical thinking skills of students in the Statistical Method I subject. Critical thinking skills are very important to bring someone to think and work carefully, sorting out relevant information, solving problems, and doing tasks on a bigger scale. This research is a classroom action research consisting of two cycles. The subjects of this study were class IIA students of Mathematics Education Study Program, Faculty of Teacher Training and Education, Mahasaraswati University Denpasar as many as 16 students in academic year 2018/2019. Data collection techniques used was observation, interviews, and tests. This study used 2 data analysis techniques namely qualitative analysis and quantitative analysis. Qualitative analysis uses models such as mathematical models and analyses that are carried out limited to data management techniques by performing descriptions. Quantitative data analysis measures the learning outcomes in the form of scores and percentages using a simple level of calculation such as average score and learning completeness percentage. The results of this study showed an improvement in students’ mathematical critical thinking skills from the first cycle to the second cycle. In the first cycle, the average score of students’ mathematical critical thinking skills was 71.125 with the learning completeness percentage only reached 62.5%. In the second cycle, the average score of students’ mathematical critical thinking skills increased significantly by 84.125 with the learning completeness percentage reached 87.5%. This study concluded that the application of “What-If” learning strategies can improve students’ mathematical critical thinking skills in the subject of Statistical Method I.
Contribution of teacher’s teaching skills and students’ intrapersonal intelligence toward metacognitive awareness of students in state vocational school in Blitar
Authors: Maryati T , Khasanah S U , Maf’ula V Y
Published: March 2020

Vocational High School graduates who can study independently will become lifelong learners who are responsive to change so they can compete in the workforce of the revolutionary era 4.0. But the learning process at Vocational High School is still not paying attention to the development of high-level thinking skills of students. This is in line with the opinion of Mukhadis that the implementation of learning in the field of technology is still less encouraging which has an impact on the lack of development of individual abilities to develop high-level thinking skills, namely metacognition. Metacognitive awareness of Vocational students is still not suspected because of several aspects, that is internal and external aspects. Internal aspects are factors that influence students from themselves, one of them is intrapersonal intelligence. Then the external aspect is a factor that influences from outside the student’s teaching skills. Given the importance of this metacognitive awareness, the authors conducted a study on the contribution of teacher teaching skills, intrapersonal intelligence to the metacognitive awareness of vocational students in computer network engineering study program in Blitar City. This study aims to determine how much the contribution of teacher teaching skills and intrapersonal intelligence of students to the metacognitive awareness of vocational students in computer engineering and network expertise packages in Blitar City. The type and analysis of data in this study are included in quantitative research. The number of samples used was 57 students in class X. Data collection techniques for variable teaching skills, intrapersonal intelligence and metacognitive awareness using questionnaires. Data analysis includes description and multiple regression.The results show as follows that, there is no significant contribution to partial teaching skills to the metacognitive consciousness; there is a significant contribution to the contribution of students’ intrapersonal intelligence partially towards the students’ metacognitive awareness of 44.22% and there is also a significant contributions to teacher teaching skills and intrapersonal intelligence of students to the students’ metacognitive awareness of 52.8%.
Design research on calculus: Students’ journey in learning definition of definite integral
Authors: Tasman F , Suherman  , Ahmad D
Published: March 2020

Some researchers report that students find difficulties in learning definition of definite integration. Therefore, classroom activities designed with design research method to help university students gain better understanding on this topic. In order to support students, realistic mathematics approach was chosen. Series of instructional activities had been designed to reach mathematical goal. Thirty of first year university students in Universitas Negeri Padang were chosen to implement the classroom activities that have been designed. This paper will report students’ journey in learning definition of definite integral in our local instructional theory (LIT). The research shows that students understanding about area, function, inscribed/circumscribed polygon, limit play important role to understand the definition of definite integral. Students need to see those concepts as a unit which cannot be separated to understand the definition of definite integral in a designed classroom activity.
Overcoming the difficulty of understanding systems of linear equations through learning ethnomathematics
Authors: Widada Wahyu , Herawaty Dewi , Rahman Mohammad H , Yustika Dita , Gusvarini Elsa P , Falaq Dwi Anggoro Abdurrobbil
Published: March 2020

Middle school students have difficulty in understanding the system of linear equations. Ethnomathematics learning was one alternative to overcome it. The purpose of this study was to describe ethnomathematics learning techniques to overcome students’ difficulties in understanding systems of linear equations. This research was part of development research. This is part of student analysis. The subjects of this study were 38 junior high school students in the Kota Bengkulu. The application of ethnomathematics learning was given to the subject. The instrument of this study was the researchers themselves with interview guides and observation sheets. It was an interview about the ability of students to understand systems of linear equations. Data were analyzed qualitatively with fixed comparison techniques. The results of this study are the difficulty of students understanding the system of linear equations can be overcome through learning ethnomathematics. The horizontal mathematization used the culture of the fishermen of Bengkulu people “bundled fish, rice as small, relaxed”. This culture makes it easy for students to recall prerequisite concepts, making it easier for students to do interconnection between concepts. This makes it easy for students to achieve the principles of elimination, substitution and mixtures. The conclusion of this study is that learning ethnomatematics about Bengkulu fisherman culture can overcome the difficulties of students in understanding the system of linear equations.
The genetic decomposition of students about infinite series through the ethnomathematics of Bengkulu, Indonesia
Authors: Widada W , Efendi S , Herawaty D , Nugroho K U Z , Putri F R
Published: March 2020

The cognitive theory views individuals as active information processors, so that individuals were able to represent each information according to the level of knowledge they have. Student representation can be seen as its genetic decomposition. Ethnomathematics was a vehicle for unlimited series learning. The purpose of this study was to describe the genetical decomposition of students about infinite series through the Bengkulu ethnomathematics. This was the initial research from a series of development research. This stage we interviewed in depth 10 high school students in Bengkulu, Indonesia. The research instrument was the researchers themselves who were guided by interview guides about understanding concepts and the principle of infinite series. Interviews were conducted during and after Bengkulu’s ethnomathematics learning. Data were analyzed through fixed comparison techniques. The results of this study were found that students can coordinate two or more actions about convergence of sequences, but not for convergence of infinite series. Conversely, there were students who can describe a particular object about converging an infinite series but not coordinated with the processes that were built for converging sequences. Also, there were students who can coordinate the action-process related objects so that a schema of converging sequence was formed, but for infinite series only in the form of separate actions or processes. The conclusion of this study was the genetic decomposition of students in understanding the infinite series through ethnomathematics learning at the intermediate level (inter level). The student before ethnomathematics learning was at the lower level (intra and pre-intra levels).
The development of student’s worksheet use integrated model with character load at lower grade class
Authors: Amini Risda , Rusdinal  , Usmeldi  , Helsa Yullys
Published: March 2020

The result of preliminary study show that student worksheet use in Elementary School has not been optimal in helping students improve students’ knowledge, skills, and attitudes. Student worksheet cannot activate the student in learning. Therefore, worksheet use integrated model with character load was developed. The development research use a 4-D model which consists of four stages, namely define, design, develop, and assess. The research subject was a student worksheet. The respondents were teachers and first grade students at Elementary School in Padang, Indonesia. The research instruments were observation sheet, questionnaire, and learning outcomes test. The results showed that the validity of student worksheet using integrated model was categorized as valid. The practicality of teaching materials was include practical categories, based on teacher and student responses. The student worksheet was included effective categories based on student activities and learning outcomes. Student activities in learning include very high categories. Learning outcomes most students achieve minimum completeness criteria.
How should the teacher provide feedback and its follow-up in assessing mathematics learning?
Authors: Fakhrunisa F , Herman T
Published: March 2020

Assessment is one of the important things that can affect the learning process and results. During the assessment phase, teachers are required to be able to provide effective feedback and its follow-up in order to get student learning goal. This study aims to present the facts that related to how forms of feedback and follow-up carried out by mathematics teachers in a one of public high school in Cimahi, West Java. Qualitative descriptive research method is equipped with observation, interview and questionnaire used to collect the research data. Through the data collection technique, it was found that the feedback that teacher presented from the entire learning process and the assessment process was still very insufficient. Students only get information about the scores obtained from the assessment in the form of a written test. There is no descriptive feedback and appropriate follow-up that makes students still feel difficulties in implementing mathematics learning. At the end of this article, it is also presented a recommendation for providing effective feedback based on theoretical studies of the results on previous studies.
Developing chemical equilibrium practicum module based on guided inquiry to explore students’ abilities in designing experiments
Authors: Pamenang F D N , Harta J , Listyarini R V , Wijayanti L W , Ratri M C , Hapsari N D , Asy’ari M , Lee W
Published: March 2020

In welcoming chemistry learning that emphasizes the quality of students, the teacher’s role is very important. As a prospective chemistry teacher, students must be prepared critically, both in terms of mastery of teaching materials and the development of learning models that are implemented. One of the alternatives offered is guided inquiry-based learning, which aims to develop students’ abilities so that exploration can continue. This study aims to develop valid dan practical product of chemical equilibrium practicum module based on guided inquiry to be used by chemistry education students in the experiment, so that students are able to think critically and reflectively. This research is a design thinking through the framework of Empathize, Define, Ideate, Prototype, and Test (EDIPT), with chemistry education students. Supporting instruments of this research include consultation sheets, observation sheets, and student response questionnaires. Data analysis was conducted in quantitative descriptive. The results of the study show that the practicum module developed can help developing the flow of students’ thinking carefully, analyse practical needs, design varied practicum topics, and reflect on experience during designing and implementing experiments. The average of students responds well to the development of the practicum module.
Rising methane emissions from boreal lakes due to increasing ice-free days
Authors: Guo Mingyang , Zhuang Qianlai , Tan Zeli , Shurpali Narasinha , Juutinen Sari , Kortelainen Pirkko , Martikainen Pertti J
Published: March 2020

Lakes account for about 10% of the boreal landscape and are responsible for approximately 30% of biogenic methane emissions that have been found to increase under changing climate. However, the quantification of this climate-sensitive methane source is fraught with large uncertainty under warming climate conditions. Only a few studies have addressed the mechanism of climate impact on the increase of northern lake methane emissions. This study uses a large observational dataset of lake methane concentrations in Finland to constrain methane emissions with an extant process-based lake biogeochemical model. We found that the total current diffusive emission from Finnish lakes is 0.12 ± 0.03 Tg CH4 yr−1 and will increase by 26%–59% by the end of this century depending on different warming scenarios. We discover that while warming lake water and sediment temperature plays an important role, the climate impact on ice-on periods is a key indicator of future emissions. We conclude that these boreal lakes remain a significant methane source under the warming climate within this century.
Functional relations for elliptic polylogarithms
Authors: Broedel Johannes , Kaderli André
Published: March 2020

Numerous examples of functional relations for multiple polylogarithms are known. For elliptic polylogarithms, however, tools for the exploration of functional relations are available, but only very few relations are identified. Starting from an approach of Zagier and Gangl, which in turn is based on considerations about an elliptic version of the Bloch group, we explore functional relations between elliptic polylogarithms and link them to the relations which can be derived using the elliptic symbol formalism. The elliptic symbol formalism in turn allows for an alternative proof of the validity of the elliptic Bloch relation. While the five-term identity is the prime example of a functional identity for multiple polylogarithms and implies many dilogarithm identities, the situation in the elliptic setup is more involved: there is no simple elliptic analogue, but rather a whole class of elliptic identities.
RBF Neural Network Adaptive Robust Sliding Mode Control Method of Artillery Ammunition Transfer Arm
Authors: Cai Hangjun , Chen Longmiao
Published: March 2020

This paper presents a robust adaptive sliding mode control strategy using radial basis function (RBF) neural network for a kind of value controlled asymmetric cylinder electro-hydraulic servo system of an ammunition transfer arm in the presence of uncertain nonlinearity and parameter uncertainty. On the premise of setting the expected trajectory, using RBF neural networks to approximate unknown parameters, by setting appropriate neural network parameters and adaptive terms, the change trend of position parameter was estimated. The stability of close loop system is verified by the Lyapounov theory. Compared with the simulation results of PID control method and expected trajectory, RBF Neural Net sliding mode control method has smaller system tracking error, faster response and better tracking performance.
Study on the Performance of a New Type of Anionic-nonionic Surfactant
Authors: Ning Mengmeng , Zeng Zhiguo , Han Mingzhe , Xu Zhengdong , Zhang Bin , Wang Peng , Kong Weizhong , Jia Jiangfen , Liu Qilun
Published: March 2020

A series of new anionic-nonionic surfactants, biophenol polyoxyethylene ether carboxylate (BPPC), were synthesized using biophenol as raw material. The chemical structure of anionic-nonionic surfactant was determined by Fourier transform infrared spectroscopy and elemental analysis. The effects of concentration and degree of polymerization on surface tension were investigated. These new surfactants have good surface activity. The critical micelle concentration (cmc) is 9.30 × 10−3 mol/L, 8.50 × 10−3 mol/L, 8.10 × 10−3 mol/L, and 7.71 × 10−3 mol/L. The corresponding surface tensions at CMC are 28.38. mN/m, 28.60 mN/m, 30.40 mN/m, and 30.00 mN/m. Then focus on the foaming properties of BPPC. The results showed that the concentration of surfactant and Ca2+/Mg2+ had certain effects on the foaming properties and foam stability of cashew nut-based surfactants. Due to the relatively good foam properties of BPPC, it has broad application prospects in detergents and petroleum recovery.
Effects of Biochar on Absorption of Iron, Sodium and Manganese in Peach Seedlings
Authors: Wu Caifang , Li Qinyuan , Shu Junjiang , Xiao Ling , Gao Xinyu , Lin Lijin
Published: March 2020

An experiment was conducted to study the effect of biochar on absorption of iron (Fe), sodium (Na) and manganese (Mn) in peach. The results showed that compared with the control (CK), the Fe content of roots in wheat straw biochar addition (WB), corn straw biochar addition (MB) and the Fe content of leaves in paddy straw biochar addition (PB) remarkably increased by 244.8%, 265.2% and 28.3% respectively, and other treatments had no pronounced differences or apparently decreased. Biochar treatments significantly reduced the Na content of roots and significantly increased the Na content of stems and leaves with the exception of rape straw biochar addition (RB). RB and PB caused a significant decrease of the Mn content of roots and stems, expect for the Mn content of stems in RB, RB and PB significantly increased the content of Mn in leaves. The Mn content of peach seedlings in WB and MB had opposite change with RB and PB. Stated thus, MB promoted the absorption of Fe by peach seedlings, and most Fe stored in roots. Biochar treatments promoted Na accumulation in stems and leaves. RB and PB promoted the accumulation of Mn in leaves, WB and MB promoted the accumulation of Mn in roots.
Study on the design of imitative-ecological fishway in Xinjiang low-head hub
Authors: Luo Shijiao
Published: March 2020

This paper first introduces in detail the design concepts and the structure of the imitative-ecological fishway in Xinjiang low-head hub. Then, combined with the operation of fishway in a water diversion project in Xinjiang, this paper summarizes the key points to be followed in the construction of low-head imitative-ecological fishway in order to achieve the expected effect, thereby providing relevant design basis and ideas for similar projects in the future.
Observed spatial pattern of summer extreme precipitation in China and its potential links to rapid urbanization
Authors: Feng Kong
Published: March 2020

The variation and evolving tendency of extreme precipitation have received extensive concern worldwide in recent years under the background of global warming and rapid urbanization, which hold a great deal of significance for management of the risk of urban flood and waterlogging and water resources. The importance of anthropogenic factors represented by urbanization is recognized in the research of extreme precipitation variation, but its underlying mechanism and potential contribution remain unclear. Hense, the academic circles have not yet achieved consensus on this. Here we use daily precipitation dataset with 544 meteorological stations’ records to study spatial pattern of summer extreme precipitation and its potential response to urbanization from 1961 to 2010 in China. Frist, we gets each station’s threshold of extreme precipitation by using ordinary percentile method and the developed method named spatial sliding percentile. Then we define the proportion of extreme precipitation with total precipitation as the indicator to reflect extreme precipitation intensity. Based on the DMSP/OLS night light index dataset, the urbanization level of 544 meteorological stations are divided into six levels. Then we use ordinary percentile method, spatial sliding percentile and the developed method named spatial sliding anomaly to quantify the possible impact of urbanization on extreme precipitation threshold and intensity by doing a comparative analysis to 544 meteorological stations with different urbanization level. The results show that: The spatial pattern of extreme precipitation intensities derived from spatial sliding percentile is more distinguishable. Effects of urbanization make the threshold increased by 1.68% and there is a significant linear correlation between the average of extreme precipitation intensity and urbanization level, namely the intensity of extreme precipitation will increase by 0.62%, when the urbanization level increases by one grade. Therefore, effects of urbanization increase the risk of summer extreme precipitation of China.
Optimization of domestic inter-regional virtual water trade of agriculture products in China
Authors: Cai Rong , Hu Mengting , Guo Huiting , Fang Fei , Liu Jing , Zhang Sinan , Bai Xue , Zhang Lijia
Published: March 2020

In the face of increasingly severe pressure on water resources, the theory of virtual water and virtual water trade provides feasible solutions for improving the efficiency of global water use for agricultural products and alleviating the pressure on water resources in water scarce countries or regions. Optimizing the domestic inter-regional trade of virtual water trade of agricultural products can provide information to help for the formulation of China’s water policy. In this study, we will establish scenarios from the two aspects of economy and water resources allocation and utilization, to study the impact of virtual water trade on water saving of agricultural products trade between regions in China. One scenario does not consider water conservation, only economic revenue - net social revenue maximization scenario. Another way to consider water saving is to maximize water saving. With the maximization of net social revenue, 9.6 billion m3 of virtual water had been exported to other regions in the severe drought regions, saving 18.6 billion m3 of water in China. The net social revenue is 9.1 billion RMB. In the scheme of water-saving maximization, virtual water is exported to water rich regions in severe, moderate and mild drought areas, and China had saved 21.5 billion m3 of water. China’s net social revenue is 4 billion RMB. The results show that the optimization of agriculture products domestic inter-regional trade can have a favorable impact on the allocation and utilization of water resources.
Influence of proppant embedment on fracture conductivity
Authors: Zhang Kui , Kang Yunwei , He Xiaodong , Guo Zixi , Tian Gang
Published: March 2020

Using the national invention patent equipment, the proppant embedment experiment was carried out on the formation coal seam. The effects of proppant embedment on the conductivity of cracks under different proppant types, different proppant particle sizes, different sanding concentrations and different closing pressures were investigated. The experimental results show that with the increase of the closing pressure, the conductivity of quartz sand and ceramsite decreases rapidly; the conductivity of ceramsite is generally higher than that of quartz sand; the higher the concentration of sand, the proppant filling The stronger the layer’s compressive capacity and crushing resistance, the higher the fracture conductivity. XY ceramsite has the best conductivity.
The effect of axis ratio on the vortex-induced vibration of an elliptical cylinder
Authors: Kushwaha Vijay , Bao Yan , Zhou Dai , Nepali Ramesh
Published: March 2020

A numerical investigation is conducted to study the vortex-induced vibration (VIV) of an elliptical body subjected to transverse oscillation with the non-dimensionless mass (mr
) fixed to be 10 and Reynolds number set to be 100. Three sets of axis ratio (Λ) are considered in the analysis where, Λ is defined as the ratio of the major and minor axis, with minor axis aligned parallel to the flow. Spectral/hp element-based software, Nektar++ is employed for the solution of incompressible flow equations. The computations are conducted for reduced velocity ranging from 2≤U*
≤9. The amplitude response is directly proportional to the increase in axis ratio in association with the pre-initiation of lock-in regime for higher axis ratio. It is also noticed that the initial branch gets widened, whereas the lower branch is constricted when the axis ratio of the cylinder is increased. However, the vortex shedding pattern in all the branches is observed to be 2S and its various modes.
Study on the influence of sand liquefaction caused by earthquake on the floating of underground structures
Authors: Wang Kaiping , Yang Lingqiang , Yao Jifei
Published: March 2020

The effective stress of the soil decreases and the pore water stress increases under the earthquake, which causes the sand to liquefy. The vertical deformation of the ground caused by the liquefaction of sand causes serious damage to the ground and the buried structure, which seriously threatens the safety of underground lifeline engineering. In order to study the impacts of sand liquefaction, the language FORTRAN was used to establish a finite element model under the earthquakes. The floating of various locations of the underground structure under different earthquakes was studied, and the factors affecting the floating were discussed. The results show that during the earthquake, the liquefaction of sand occurs, which causes the underground structure moves up due to buoyancy, and the soil mass from the structure collapses. The liquefied sand diffuses to the surrounding area after the earthquake, causing the sand beneath the underground structure to be lost, and the building will return to its original position or even collapse. The results provide references for the anti-floating research of underground structures.
Application of time-frequency image feature extraction method based on gray level co-occurrence matrix in coal mine pipeline leakage detection
Authors: Han Wenbei , Zhao Hongliang , Zhao Ziwei , Gu Fengshou , Zhen Dong
Published: March 2020

The underground mining environment of coal mine is complex. Once the water supply or gas supply pipes leak, the location and time of leakage are unpredictable. If the leakage can not be found in time, it will seriously threaten the life safety of underground workers. Therefore, it is very necessary to automatically detect the pipeline leakage. In order to solve the problem of automatic detection of coal mine pipeline leakage, this paper proposes an image processing method based on gray level co-occurrence matrix to extract the features of time-frequency image of vibration signal. Firstly, the data in a relatively short time is divided into one frame to reduce the amount of calculation. Secondly, each frame of signal is processed by SPWVD to get the time-frequency image. Then, the time-frequency image after time-frequency analysis is transformed into gray-scale image, and the gray-scale co-occurrence matrix (GLCM) of the image is extracted. Finally, the energy, contrast and correlation of the co-occurrence matrix are extracted and input to SVM for learning and training. Through the design and build of the experimental pipeline to test the algorithm proposed in this paper, the detection result of SVM is 96.67%, which shows that this method can effectively detect the pipeline leakage.
Decay estimate and global existence of a semilinear Mindlin-Timoshenko plate system with full frictional damping in the whole space
Authors: Li Kaiqiang , Xue Rui
Published: March 2020

In this paper, we are interested in a semilinear Mindlin-Timoshenko system with an irrotationality condition for the angle variables. Under the smallness assumption on the initial data, the decay rate of solutions is obtained by using both the multiplier method in the Fourier space and the fundamental solution method. Moreover, we also prove the global existence of solutions by the standard method.
The Impact of Delayed Switch to Second-Line Antiretroviral Therapy on Mortality, Depending on Definition of Failure Time and CD4 Count at Failure
Authors: Bell-Gorrod Helen , Fox Matthew P , Boulle Andrew , Prozesky Hans , Wood Robin , Tanser Frank , Davies Mary-Ann , Schomaker Michael
Published: March 2020

Little is known about the functional relationship of delaying second-line treatment initiation for human immunodeficiency virus–positive patients and mortality, given a patient’s immune status. We included 7,255 patients starting antiretroviral therapy during 2004–2017, from 9 South African cohorts, with virological failure and complete baseline data. We estimated the impact of switch time on the hazard of death using inverse probability of treatment weighting of marginal structural models. The nonlinear relationship between month of switch and the 5-year survival probability, stratified by CD4 count at failure, was estimated with targeted maximum likelihood estimation. We adjusted for measured time-varying confounding by CD4 count, viral load, and visit frequency. Five-year mortality was estimated to be 10.5% (95% CI: 2.2, 18.8) for immediate switch and to be 26.6% (95% CI: 20.9, 32.3) for no switch (51.1% if CD4 count was <100 cells/mm3). The hazard of death was estimated to be 0.37 (95% CI: 0.30, 0.46) times lower if everyone had been switched immediately compared with never. The shorter the delay in switching, the lower the hazard of death—delaying 30–59 days reduced the hazard by 0.53 (95% CI: 0.43, 0.65) times and 60–119 days by 0.58 (95% CI: 0.49, 0.69) times, compared with no switch. Early treatment switch is particularly important for patients with low CD4 counts at failure.
Myths of the Odyssey in the British Museum (and beyond): Jane Ellen Harrison’s museum talks and their audience
Authors: Baker Abigail
Published: March 2020

Jane Ellen Harrison’s early work giving tours and lectures in London’s museums offers an unusual window on visitor experience in the late nineteenth century. This article examines the composition and motivations of her audience, looking at how Harrison’s lectures addressed gendered and class-based anxieties about their access to education and ability to respond appropriately to prestigious objects. Harrison used Greek vases to tell stories from ancient Greek literature. She made the case for the value of Greek vases as a repository of stories that could be understood through comparisons with literature but which also stood as evidence in their own right, hinting at lost stories and the perspectives of ordinary people. Her museum talks demonstrate a belief that Greek vases offered an alternative to Classical literature, one which had been made by ordinary people in the past and could be ‘read’ by ordinary people in the present.
Are Patients with Inflammatory Bowel Disease at Increased Risk for Covid-19 Infection?
Authors: Monteleone Giovanni , Ardizzone Sandro
Published: March 2020

Crohn’s disease [CD] and ulcerative colitis [UC], the main inflammatory bowel diseases [IBD] in humans, are chronic, immune-inflammatory diseases, the pathogenesis of which suggests a complex interaction between environmental factors and genetic susceptibility. These disabling conditions affect millions of individuals and, together with the drugs used to treat them, can put patients at risk of developing complications and other conditions. This is particularly relevant today, as coronavirus disease [Covid-19] has rapidly spread from China to countries where IBD are more prevalent, and there is convincing evidence that Covid-19-mediated morbidity and mortality are higher in subjects with comorbidities. The primary objectives of this Viewpoint are to provide a focused overview of the factors and mechanisms by which the novel severe acute respiratory syndrome coronavirus 2 [SARS-CoV-2] infects cells and to illustrate the link between such determinants and intestinal inflammation. We also provide clues about the reasons why the overall IBD population might have no increased risk of developing SARS-CoV-2 infection and highlight the potential of cytokine blockers, used to treat IBD patients, to prevent Covid-driven pneumonia.
The effect of facemask in patients with unilateral cleft lip and palate: a systematic review and meta-analysis
Authors: Palikaraki Georgia , Makrygiannakis Miltiadis A , Zafeiriadis Anastasios A , Benetou Vassiliki , Sanoudos Mattheos , Bitsanis Ilias , Tsolakis Apostolos I
Published: March 2020

Background

Patients with cleft lip and palate usually present a Class III skeletal pattern. Facemask (FM) is one of the conventional orthodontic treatment modalities used to address the skeletal discrepancy in cleft patients.

Objective

To investigate the potential effectiveness of FM in unilateral cleft lip and palate (UCLP) patients.

Search methods

Search without restrictions except language in seven databases since inception and hand searching until January 2019 was conducted. Detailed search strategies were developed for each database which were based on the PubMed strategy and adapted accordingly.

Selection criteria

Controlled studies assessing the effect of FM in UCLP patients were to be included.

Data collection and analysis

After retrieval and selection of the studies, data extraction was performed. Both angular and linear cephalometric measurements were collected. Weighted mean differences (WMDs) and 95% confidence intervals (CΙs) between treated and untreated UCLP patients concerning the pre- and post-treatment angular measurements of each group were calculated using a random-effects meta-analysis model. The risk of bias in individual studies was assessed using the ROBINS-I tool.

Results

From nine eligible studies, five were included in the meta-analysis investigating the use of FM in patients and controls with UCLP (with and without maxillary expansion). Statistically significant differences were evident for SNA/S–N–ss, SNB/S–N–sm, ANB/ss–N–sm, and SN–MP. FM was found to induce an increase of SNA (WMD = 2.12 degrees, 95% CI: 1.58 to 2.66), ANB (WMD = 4.17 degrees, 95% CI: 3.60 to 4.74), and SN–MP angles (WMD = 2.60 degrees, 95% CI: 1.10 to 4.10) and a decrease of SNB angle (WMD = −1.94 degrees, 95% CI: −2.48 to −1.40) in UCLP patients. Low to moderate heterogeneity was observed.

Limitations

They emerge due to risk of bias, exclusion of non-English papers and methodological characteristics of the included papers.

Conclusions

According to the available data, FM seems to improve the sagittal skeletal relationships in UCLP patients, increasing the SNA and ANB angles and decreasing the SNB angle. Moreover, in the vertical dimension, FM increases the SN–MP angle. Regarding dental measurements, there are controversial results. More high-quality studies need to be conducted in order to further clarify the impact of FM on UCLP patients.

Registration number

PROSPERO: CRD42019131619.
Comparison of in-hospital outcomes and readmissions for valve-in-valve transcatheter aortic valve replacement vs. reoperative surgical aortic valve replacement: a contemporary assessment of real-world outcomes
Authors: Hirji Sameer A , Percy Edward D , Zogg Cheryl K , Malarczyk Alexandra , Harloff Morgan T , Yazdchi Farhang , Kaneko Tsuyoshi
Published: March 2020

Aims

We sought to perform a head-to-head comparison of contemporary 30-day outcomes and readmissions between valve-in-valve transcatheter aortic valve replacement (VIV-TAVR) patients and a matched cohort of high-risk reoperative surgical aortic valve replacement (re-SAVR) patients using a large, multicentre, national database.

Methods and results

We utilized the nationally weighted 2012–16 National Readmission Database claims to identify all US adult patients with degenerated bioprosthetic aortic valves who underwent either VIV-TAVR (n = 3443) or isolated re-SAVR (n = 3372). Thirty-day outcomes were compared using multivariate analysis and propensity score matching (1:1). Unadjusted, VIV-TAVR patients had significantly lower 30-day mortality (2.7% vs. 5.0%), 30-day morbidity (66.4% vs. 79%), and rates of major bleeding (35.8% vs. 50%). On multivariable analysis, re-SAVR was a significant risk factor for both 30-day mortality [adjusted odds ratio (aOR) of VIV-SAVR (vs. re-SAVR) 0.48, 95% confidence interval (CI) 0.28–0.81] and 30-day morbidity [aOR for VIV-TAVR (vs. re-SAVR) 0.54, 95% CI 0.43–0.68]. After matching (n = 2181 matched pairs), VIV-TAVR was associated with lower odds of 30-day mortality (OR 0.41, 95% CI 0.23–0.74), 30-day morbidity (OR 0.53, 95% CI 0.43–0.72), and major bleeding (OR 0.66, 95% CI 0.51–0.85). Valve-in-valve TAVR was also associated with shorter length of stay (median savings of 2 days, 95% CI 1.3–2.7) and higher odds of routine home discharges (OR 2.11, 95% CI 1.61–2.78) compared to re-SAVR.

Conclusion

In this large, nationwide study of matched high-risk patients with degenerated bioprosthetic aortic valves, VIV-TAVR appears to confer an advantage over re-SAVR in terms of 30-day mortality, morbidity, and bleeding complications. Further studies are warranted to benchmark in low- and intermediate-risk patients and to adequately assess longer-term efficacy.