bluuebunny/crossref_metadata_2025 huggingface dataset:
Influencing factors of rotary table geometric error measurement using four-station laser tracers
Authors: Zha Jun
Published: December 2021

The laser tracer multi-station measurement method has outstanding performance in computerized numerical control (CNC) rotary table geometric error measurement and separation. However, external factors, such as layout, selected distance between the target mirror and measurement coordinate system, uncertainty of the length measurement, selection of measuring radii for the rotary table, and installation deviation from the target mirror center to the rotary table surface, have negative effects on the results. In this research, the position dilution of precision in the global positioning system measurement process is introduced to evaluate the influence of the laser tracers’ positions on measurement errors. The optimal measurement layout of the laser tracer is used to select the distance between the target mirror and XY plane of the laser tracer measurement coordinate system for the simulation. Then, the influence of the length measurement uncertainty on the laser tracer self-calibration and point measurement results used for calibration is examined based on the Monte Carlo simulation method. Different measurement radii in the rotary table are selected, and four-station laser tracers are used to perform the virtual measurement and evaluate the maximum uncertainty in the X, Y, and Z directions to further determine the best measurement radii of the CNC rotary table. Finally, the effects of the deviation of the target mirror installation center on the geometric error items of the CNC rotary table are quantitatively examined through a simulation. The analysis of the influencing factors in the geometric error measurement and separation process of the CNC rotary table can help further understand how the final results are formed, so as to control the influencing factors during the measurement process and finally optimize them in practice.
A blind deconvolution algorithm based on backward automatic differentiation and its application to rolling bearing fault diagnosis
Authors: Fang Bo , Hu Jianzhong , Yang Cheng , Cao Yudong , Jia Minping
Published: December 2021

Blind deconvolution (BD) is an effective algorithm for enhancing the impulsive signature of rolling bearings. As a convex optimization problem, the existing BDs have poor optimization performance and cannot effectively enhance the impulsive signature excited by weak faults. Moreover, the existing BDs require manual derivation of the calculation process, which brings great inconvenience to the researcher’s personalized design of the maximization criterion. A new BD algorithm based on backward automatic differentiation is proposed, which is named backward automatic differentiation blind deconvolution (BADBD). The calculation process does not require manual derivation so a general solution of BDs based on different maximization criteria is realized. BADBD constructs multiple cascaded filters to filter the raw vibration signal, which makes up for the deficiency of single filter performance. The filter coefficients are determined by Adam algorithm, which improves the optimization performance of the proposed BADBD. BADBD is compared with classic BDs by synthesized and real vibration signals. The results reveal superior capability of BADBD to enhance the impulsive signature and the fault diagnosis performance is significantly better than the classic BDs.
Defect control and Si/Ge core–shell heterojunction formation on silicon nanowire surfaces formed using the top-down method
Authors: Fukata Naoki , Jevasuwan Wipakorn , Sun Yong-Lie , Sugimoto Yoshimasa
Published: December 2021

Control of surface defects and impurity doping are important keys to realizing devices that use semiconductor nanowires (NWs). As a structure capable of suppressing impurity scattering, p-Si/i (intrinsic)-Ge core–shell NWs with radial heterojunctions inside the NWs were formed. When forming NWs using a top-down method, the positions of the NWs can be controlled, but their surface is damaged. When heat treatment for repairing surface damage is performed, the surface roughness of the NWs closely depends on the kind of atmospheric gas. Oxidation and chemical etching prior to shell formation removes the surface damaged layer on p-SiNWs and simultaneously achieves a reduction in the diameter of the NWs. Finally, hole gas accumulation, which is important for suppressing impurity scattering, can be observed in the i-Ge layers of p-Si/i-Ge core–shell NWs.
An all two-dimensional vertical heterostructure graphene/CuInP2S6/MoS2 for negative capacitance field effect transistor
Authors: Liaqat Adeel , Yin Yiheng , Hussain Sabir , Wen Wen , Wu Juanxia , Guo Yuzheng , Dang Chunhe , Ho Ching-Hwa , Liu Zheng , Yu Peng , Cheng Zhihai , Xie Liming
Published: December 2021

As scaling down the size of metal oxide semiconductor field-effect transistors (FETs), power dissipation has become a major challenge. Lowering down the sub-threshold swing (SS) is known as an effective technique to decrease the operating voltage of FETs and hence lower down the power consumption. However, the Boltzmann distribution of electrons (so-called ‘Boltzmann tyranny’) implements a physical limit to the SS value. Use of negative capacitance (NC) effect has enabled a new path to achieve a low SS below the Boltzmann limit (60 mV dec−1 at room temperature). In this work, we have demonstrated a NC-FET from an all two-dimensional (2D) metal ferroelectric semiconductor (MFS) vertical heterostructure: Graphene/CuInP2S6/MoS2. The negative capacitance from the ferroelectric CuInP2S6 has enabled the breaking of the ‘Boltzmann tyranny’. The heterostructure based device has shown steep slopes switching below 60 mV dec−1 (lowest to < 10 mV dec−1) over 3 orders of source-drain current, which provides an avenue for all 2D material based steep slope FETs.
Demonstrating the first postulate of relativity in a lift
Authors: Hughes Stephen , Croxford Tim
Published: December 2021

The first of the two postulates of relativity states that the laws of physics are the same in all inertial reference frames. Often it is assumed that the postulates are mainly concerned with objects moving at a significant fraction of the speed of light. However, the postulates are applicable at all speeds from a snail to a photon. To practically demonstrate the first postulate, the time for a ball to drop a known distance was measured in a stationary and moving lift. An accelerometer app on an iPhone 7 was used to measure the vertical acceleration while the lift travelled between floors and verified that the lift ascended and descended at a constant speed when the ball was dropped. The slow-motion feature of the iPhone 7 (240 fps) was used to capture videos of the falling ball. The number of frames for the ball to fall in a stationary, descending, and ascending lift was respectively

102.4
±
0.55
,
102.3
±
1.64
,
99.8
±
4.21.

A t-test revealed no significant difference between these values, confirming the validity of the first postulate. The accelerometer signal was integrated to estimate the average speed of the lift between the bottom and top floor, which was then used to estimate the height difference. An electronic balance placed on the floor of the lift was used to demonstrate the first postulate and the equivalence principle of General Relativity that states that gravitational and inertial mass are equivalent.
A Faraday’s law paradox
Authors: Cross Rod
Published: December 2021

The voltage drop or potential difference across a resistor is easily measured with a voltmeter. However, if the loop formed by the resistor, the connecting leads, and the voltmeter surrounds a changing magnetic field then the measured voltage drop will be different. This result can lead to a paradox when using Faraday’s law.
High-speed micro-LEDs for visible light communication: challenges and progresses
Authors: Yu Luming , Wang Lai , Hao Zhibiao , Luo Yi , Sun Changzheng , Xiong Bing , Han Yanjun , Wang Jian , Li Hongtao
Published: December 2021

Due to spectrum shortage, visible light communication (VLC) has gradually been regarded as an important alternative and reinforcement in wireless communication field. Micro-light-emitting diodes (micro-LEDs) are ideal high-speed light sources for VLC due to its significantly improved modulation bandwidth. In this review, the developments of high-speed micro-LEDs in VLC are discussed. While expounding the unique advantages of micro-LED, we also point out the existing problems and challenges. On this basis, we review the outstanding achievements in bandwidth improvement, and also look forward to some promising directions for future research.
On the design workflow of auxetic metamaterials for structural applications
Authors: Wallbanks Matthew , Khan Muhammad Farhan , Bodaghi Mahdi , Triantaphyllou Andrew , Serjouei Ahmad
Published: December 2021

Auxetic metamaterials exhibit an unexpected behaviour of a negative Poisson’s ratio (NPR), meaning they expand transversely when stretched longitudinally. This behaviour is generated predominantly due to the way individual elements of an auxetic lattice are structured. These structures are gaining interest in a wide variety of applications such as energy absorption, sensors, smart filters, vibration isolation and medical etc. Their potential could be further exploited by the use of additive manufacturing. Currently there is a lack of guidance on how to design these structures. This paper highlights state-of-the-art in auxetic metamaterials and its commonly used unit-cell types. It further explores the design approaches used in the literature on creating auxetic lattices for different applications and proposes, for the first time, a workflow comprising design, simulation and testing of auxetic structures. This workflow provides guidance on the design process for using auxetic metamaterials in structural applications.
A fast-response electroactive actuator based on TEMPO-oxidized cellulose nanofibers
Authors: Huang Yan , Wang Fang , Qian Liying , Cao Xiuhua , He Beihai , Li Junrong
Published: December 2021

Cellulose-based electroactive actuators are promising candidates for biomimetic robots and biomedical applications due to their lightweight, high mechanical strength, and natural abundance. However, cellulose-based electroactive actuators exhibit lower actuation performance than traditional conductive polymer actuators. This work reports a fast-response cellulose-based electroactive actuator based on 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) oxidized nanocellulose (TOCNF) film with layered structure fabricated by evaporation, and gold electrodes prepared by ion sputtering. The residual ions during the TEMPO oxidation process and the layered structure due to self-assembly accelerate the ion migration efficiency in actuators. The proposed actuator can reach a tip displacement of 32.1 mm at a voltage of 10 V and deflect 60° in 5 s. After applying a reverse 10 V voltage, the actuator can also be quickly deflected (42.5 mm). In addition, the actuator also shows high electrical actuation performance at low voltage (5 V). The excellent electroactive performance of as-prepared TOCNF/Au enables the feasibility to be applied to actuators.
Focusing phase imaging for Lamb wave phased array
Authors: Lang Yan-Feng , Tian Shao-Hua , Yang Zhi-Bo , Zhang Wei , Kong De-Tong , Xu Kai-Liang , Chen Xue-Feng
Published: December 2021

In Lamb wave-based structural health monitoring, amplitude damage imaging is commonly used because the defects feature can be easily amplified by summing all the response signals together. However, the grating and side lobes affect the imaging quality and blind areas further restrict the inspection area. Considering that the existing phase-based imaging algorithms are either unfit for dispersive Lamb wave or strict to many requirements to guarantee better performance, inspired by the absence of phase information in focusing phased array, a novel focusing phase imaging (FPI) method for Lamb wave phased array is developed. The main contribution of the paper is introducing the phase information to focusing phased array. By applying the inverse-dispersion effect to the excitation signals and the superposition operation, the energy can be focused at every inspection point. The phase damage index is constructed by directly measuring the degree of consistency and alignment of the instantaneous phases. The experiments for the circular and linear array under various excitation signals with multiple defects verify that the FPI is effective for both surface damage and through-hole damage. The proposed algorithm is superior for its ability in energy focusing for defects, the capability in suppression of grating and side lobes, strong anti-disturbance ability from boundary reflection, the nonexistence of imaging blind area, and its adaptability for various excitation parameters and array layout.
Switchable spiral Josephson junction: a superconducting spin-valve proposal
Authors: Pugach N G , Heim D M , Seleznev D V , Chernov A I , Menzel D
Published: December 2021

We propose a superconducting spin valve based on a Josephson junction with B20-family magnetic metal as a barrier material. Our analysis shows that the states of this element can be switched by reorienting the intrinsic non-collinear magnetization of the spiral magnet. This reorientation modifies long-range spin-triplet correlations and thereby strongly influences the critical Josephson current. Compared to superconducting spin valves proposed earlier, our device has the following advantages: (a) it contains only one barrier layer, which makes it easier to fabricate and control; (b) its ground state is stable, which prevents uncontrolled switching; (c) it is compatible with devices of low-T Josephson electronics. This device may switch between two logical states which exhibit two different values of critical current, or its positive and negative values. I.e. 0-π switch is achievable on a simple Josephson junction.
Detecting deformed commutators with exceptional points in optomechanical sensors
Authors: Cui Dianzhen , Li T , Li Jianning , Yi Xuexi
Published: December 2021

Models of quantum gravity imply a modification of the canonical position-momentum commutation relations. In this paper, working with a binary mechanical system, we examine the effect of quantum gravity on the exceptional points of the system. On the one side, we find that the exceedingly weak effect of quantum gravity can be sensed via pushing the system towards a second-order exceptional point, where the spectra of the non-Hermitian system exhibits non-analytic and even discontinuous behavior. On the other side, the gravity perturbation will affect the sensitivity of the system to deposition mass. In order to further enhance the sensitivity of the system to quantum gravity, we extend the system to the other one which has a third-order exceptional point. Our work provides a feasible way to use exceptional points as a new tool to explore the effect of quantum gravity.
Anti-parity-time topologically undefined state
Authors: Wang Haohao , Ji Kaiwen , Wang Yuandan , Liu Zhenjuan , Gao Yuanmei , Shen Yanlong , Bai Shi , Sugioka Koji , Qi Xinyuan
Published: December 2021

Researches on the topological edge state in the photonic lattice are attracting considerable attention. Here, we report the studies on a particular state for which the topological invariant is undefined. We constructed an anti-parity-time-symmetric photonic lattice by using the perturbation method. Light distributes only in the wide waveguides with equal magnitude for the state with undefined winding numbers. Further studies show that the equal intensity transmission is unaffected except for the defect site. Our work provides a new way to study the topological state and the equally divided light transmission and might be applicable in optical circuits and optical interconnect.
Origins of the hydrogen signal in atom probe tomography: case studies of alkali and noble metals
Authors: Yoo Su-Hyun , Kim Se-Ho , Woods Eric , Gault Baptiste , Todorova Mira , Neugebauer Jörg
Published: December 2021

Atom probe tomography (APT) analysis is being actively used to provide near-atomic-scale information on the composition of complex materials in three-dimensions. In recent years, there has been a surge of interest in the technique to investigate the distribution of hydrogen in metals. However, the presence of hydrogen in the analysis of almost all specimens from nearly all material systems has caused numerous debates as to its origins and impact on the quantitativeness of the measurement. It is often perceived that most H arises from residual gas ionization, therefore affecting primarily materials with a relatively low evaporation field. In this work, we perform systematic investigations to identify the origin of H residuals in APT experiments by combining density-functional theory (DFT) calculations and APT measurements on an alkali and a noble metal, namely Na and Pt, respectively. We report that no H residual is found in Na metal samples, but in Pt, which has a higher evaporation field, a relatively high signal of H is detected. These results contradict the hypothesis of the H signal being due to direct ionization of residual H2 without much interaction with the specimen’s surface. Based on DFT, we demonstrate that alkali metals are thermodynamically less likely to be subject to H contamination under APT-operating conditions compared to transition or noble metals. These insights indicate that the detected H-signal is not only from ionization of residual gaseous H2 alone, but is strongly influenced by material-specific physical properties. The origin of H residuals is elucidated by considering different conditions encountered during APT experiments, specifically, specimen-preparation, transportation, and APT-operating conditions by taking thermodynamic and kinetic aspects into account.
Improved alpha-beta power reduction via combined electrical and ultrasonic stimulation in a parkinsonian cortex-basal ganglia-thalamus computational model
Authors: Tarnaud Thomas , Joseph Wout , Schoeters Ruben , Martens Luc , Tanghe Emmeric
Published: December 2021

Objective. To investigate computationally the interaction of combined electrical and ultrasonic modulation of isolated neurons and of the parkinsonian cortex-basal ganglia-thalamus loop. Approach. Continuous-wave or pulsed electrical and ultrasonic neuromodulation is applied to isolated Otsuka plateau-potential generating subthalamic nucleus (STN) and Pospischil regular, fast and low-threshold spiking cortical cells in a temporally alternating or simultaneous manner. Similar combinations of electrical/ultrasonic waveforms are applied to a parkinsonian biophysical cortex-basal ganglia-thalamus neuronal network. Ultrasound-neuron interaction is modelled respectively for isolated neurons and the neuronal network with the NICE and SONIC implementations of the bilayer sonophore underlying mechanism. Reduction in

α
−
β

spectral energy is used as a proxy to express improvement in Parkinson’s disease by insonication and electrostimulation. Main results. Simultaneous electro-acoustic stimulation achieves a given level of neuronal activity at lower intensities compared to the separate stimulation modalities. Conversely, temporally alternating stimulation with

50
 

H
z

electrical and ultrasound pulses is capable of eliciting

100
 

H
z

STN firing rates. Furthermore, combination of ultrasound with hyperpolarizing currents can alter cortical cell relative spiking regimes. In the parkinsonian neuronal network, continuous-wave and pulsed ultrasound reduce pathological oscillations by different mechanisms. High-frequency pulsed separated electrical and ultrasonic deep brain stimulation (DBS) reduce pathological

α
−
β

power by entraining STN-neurons. In contrast, continuous-wave ultrasound reduces pathological oscillations by silencing the STN. Compared to the separated stimulation modalities, temporally simultaneous or alternating electro-acoustic stimulation can achieve higher reductions in

α
−
β

power for the same safety contraints on electrical/ultrasonic intensity. Significance. Focused ultrasound has the potential of becoming a non-invasive alternative of conventional DBS for the treatment of Parkinson’s disease. Here, we elaborate on proposed benefits of combined electro-acoustic stimulation in terms of improved dynamic range, efficiency, spatial resolution, and neuronal selectivity.
Non-invasive on-skin sensors for brain machine interfaces with epitaxial graphene
Authors: Faisal Shaikh Nayeem , Amjadipour Mojtaba , Izzo Kimi , Singer James Aaron , Bendavid Avi , Lin Chin-Teng , Iacopi Francesca
Published: December 2021

Objective. Brain–machine interfaces are key components for the development of hands-free, brain-controlled devices. Electroencephalogram (EEG) electrodes are particularly attractive for harvesting the neural signals in a non-invasive fashion. Approach. Here, we explore the use of epitaxial graphene (EG) grown on silicon carbide on silicon for detecting the EEG signals with high sensitivity. Main results and significance. This dry and non-invasive approach exhibits a markedly improved skin contact impedance when benchmarked to commercial dry electrodes, as well as superior robustness, allowing prolonged and repeated use also in a highly saline environment. In addition, we report the newly observed phenomenon of surface conditioning of the EG electrodes. The prolonged contact of the EG with the skin electrolytes functionalize the grain boundaries of the graphene, leading to the formation of a thin surface film of water through physisorption and consequently reducing its contact impedance more than three-fold. This effect is primed in highly saline environments, and could be also further tailored as pre-conditioning to enhance the performance and reliability of the EG sensors.
System-Scale Modeling of a Building-Integrated, Transparent Concentrating Photovoltaic and Thermal Collector
Authors: Novelli N E , Shultz J , Etman M Aly , Phillips K , Derby M M , Stark P R H S , Jensen M , Dyson A H
Published: December 2021

The buildings sector is a principal contributor to global greenhouse gas emissions, but consistently falls short of targets for harnessing on-site energy resources towards sustainable operation. Emerging integrated solar technologies could transform buildings and urban settings into resilient, self-sufficient, and healthy environments. But if effects of these technologies are not understood in the multiple contexts in which they operate (human-scale, building-scale, district-scale), their potential is difficult to project. To explore building-scale metabolization of solar energy, a previously-developed analytical model of a Building Envelope-Integrated, Transparent, Concentrating Photovoltaic and Thermal collector (BITCoPT) was run to project electrical and thermal energy and exergy production (cogeneration) in a range of orientations and operating temperatures. Simulated annual cogeneration efficiency was noted at 27% (exergy) at an operating temperature of 55°C, and up to 55% (energy) at 25°C. Exergetic efficiency remained nearly constant as operating temperatures increased through 75°C, indicating the thermal energy collected would be some heat-engine-based applications. Although the scope of this study excludes broader architectural benefits of daylighting (lighting load reduction), and reduction of solar gains (cooling loads), these results suggest BITCoPT merits further investigation for on-site net-zero and energy-positive commercial building design, and might contribute to expanding net-zero and energy-positive architecture opportunities.
Innovation Media Learning: Online Project-Based Learning (O-PBL) on Drawing Competence in Automotive Engineering Using Video on YouTube
Authors: Haryanto  , Kusuma Wahyu Mustafa , Mutohhari Farid , Nurtanto Muhammad , Suyitno Suyitno
Published: December 2021

This study aims to develop and analysis the feasibility of a video-assisted project-based learning model on YouTube in automotive engineering drawing subjects. Research development using ADDIE design which is simplified into 4 steps. The developed model was validated by material experts, media and learning practitioners as well as user perception tests. Data were collected through a questionnaire with a product feasibility questionnaire and a perception questionnaire using 5 Likert scales. The results of developing a project-based learning model assisted by YouTube videos contain planning procedures, syntax implementation, and assessment mechanisms that are packaged in a learning model guide book. The results of the validation test obtained a very high level of feasibility, both from material experts, media experts and learning practitioners. Likewise, the student response test showed a very good response to the developed model. The video-assisted project-based learning model on YouTube in automotive engineering drawing subjects is very feasible to be applied in learning.
Web-Based Recruitment Selection Application Development with Analytical Hierarchy Process (AHP) Method
Authors: Maruanaya G J T , Maruanaya R F , Hariyanto D
Published: December 2021

This research aimed to design and develop a support system to determine the selection of recruitment, especially assistant for the Integrated ICT Laboratory at Budi Luhur University according to predetermined criteria. The method used in developing the application was the Analytical Hierarchy Process (AHP) method, which was to rank decision alternatives and accept the excellence one for several criterion cases that mixes qualitative and quantitative components in the whole assessment of available alternatives. The results showed that there were 6 (six) criteria in the selection of the Integrated ICT Laboratory Assistant, including Attendance Value, Competency Value, Project Value, Hardware Value, Interview Value, and Psychological Test Value, which were in accordance with the criteria in the Integrated ICT Laboratory at Budi Luhur University. The system can speed up the process of accepting assistants, because the calculation process, as well as printing the final score are in one system, according to the terms and criteria specified, making it more effective and efficient.
Association of Population Density and Distance to the City with the Risks of COVID-19: A Bayesian Spatial Analysis
Authors: Tiro M A , Aswi A , Rais Z
Published: December 2021

The outbreak of Coronavirus disease-2019 (Covid-19) poses a severe threat around the world. Although several studies of modelling Covid-19 cases have been done, there appears to have been limited research into modelling Covid-19 using Bayesian hierarchical spatial models. This study aims to examine the most suitable Bayesian spatial CAR Leroux models in modelling the number of confirmed Covid-19 cases without and with covariates namely distance to the capital city and population density. Data on the number of confirmed positive cases of Covid-19 (March 20, 2020 - August 30, 2021) in 15 sub-districts in Makassar City, the number of populations, population density, and distance to the city are used. The best model selection is based on several criteria, namely Deviance Information Criteria (DIC), Watanabe Akaike Information Criteria (WAIC), residuals from Moran’s I Modification (MMI), and the 95% credible interval does not contain zero. The results showed that the best model in modelling Covid-19 is spatial CAR Leroux with hyperprior Inverse-Gamma (0.5, 0.05) model with the incorporation of distance to the capital city. It is found that there was a negative correlation between the distance to the capital city and Covid-19 risk, but the association between population density and the relative risk of Covid-19 was not statistically significant. Ujung Pandang district and Sangkarrang Island have the highest and the lowest relative risk respectively.
Logistics Regression Modelling on Student Career Path Choices at the Statistics Department, FMIPA UNM Makassar
Authors: Tiro M A , Poerwanto B , Fahmuddin M
Published: December 2021

Survey of career path that students plan after completing their undergraduate in statistics department was carried out through questionnaire on google form from May 6 to May 24, 2021. There were 114 students who filled out the questionnaire, consisting of 20 students from class 2018, 23 students from class 2019, and 71 students from class 2020. Dependent variable is career path plan (Y), while independent variables are tendency to choose career paradigm (CPC), gender (GDR), Grade Point Average (GPA), parental occupation (POC), number of siblings (NOS), place of birth (POB) and year of university entrance (YOE). The data are analysed by binary logistic model with logit transformation and the result is

g
(
Y
)
=
ln
[

π
(
Y
)

1
−
π
(
Y
)

]
=
−
13
,
525
+
2
,
332
(
CPC
)
−
1
,
036
(
GDR
)
+
4
,
466
(
GPA
)
+
2
,
421
(

POC

1

)
−
0
,
405
(

POC

2

)
+
2
,
390
(

POC

3

)
+
0
,
236
(
NOS
)
−
1
,
817
(
POB
)
+
0
,
448
(

YOE

1

)
−
2
,
660
(

YOE

2

)

Results of the analysis show that predictive power of the model to explain tendency of students to choose career according to statistics is around 34% to 56% based on variables in the model. Beside that tendency of career paradigm choice (CPC), Grade Point Average (GPA), parental occupation (POC1 civil servant), place of birth (POB), and year of entry (YOE2 2019) significantly affect chosen career goals by student.
Development of Learning Devices for the Method in The Bamboo Dancing Stage of Defining A 4-D Model on Triangle Material in Class VII
Authors: Arvyaty  , Arapu L , Jazuli L O A , Mursidin  , Lestari RV
Published: December 2021

This study aims to determine the process and results of defining the development of learning devices with the method bamboo dancing in the triangular material of class VII SMP. This research is a type of development research. The research procedure uses a 4-D model in the stage define. The research results obtained are: the need for the availability of learning tools in the classroom, the needs of students based on the background knowledge and level of cognitive development, the order of the material and the allocation of learning time, the combination of methods bamboo dancing and techniques scaffolding, and indicators of learning objectives. Based on the results of the study, it was concluded that: a) The use of methods bamboo dancing and techniques scaffolding can meet the needs of students in understanding triangle material with conceptual understanding, b) Presentation of triangle material based on basic competencies in the syllabus, indicators of competency achievement and specification of learning objectives, implementation of learning with sub material: understanding triangular flat shapes, types and properties of triangular flat shapes, perimeter and area of riangular flat shapes, special lines and points on triangles, and area of irregular flat shapes.
The Analysis of Mangrove Area as a Marine Eco-Fisherytourism Area in Luwu Regency South Sulawesi, Indonesia
Authors: Arfan A , Nyompa S , Rakib M , Juanda M F
Published: December 2021

Marine eco-fisherytourism is an approach to balancing the existing natural environments and conservation efforts to managing mangrove resources and exploring mangrove areas based on the adapting of silvofishery system support successfully the sustainable forest production. This study investigated the sustainability and profitability of mangrove areas by growing and expanding marine eco-fisherytourism areas. An observational study, intensive individual assessment using role-specific questions to the community around the mangrove area, local government, non-governmental organizations, and community leaders; and High-Resolution Satellite Imagery from Bing Maps, Google Maps, and Aerial Drone Photography has been collected. Strengths, Weaknesses, Opportunities, dan Threats (SWOT) analysis is suggested to determine how the productivity of mangrove forests development contributes to marine eco-fisherytourism. This analysis shows that the internal factors analysis strategy (IFAS) is approximately 1,09 while the external factors analysis strategy (EFAS) slightly drops to -1,38. Diversification strategy indicates innovation gains across internal factors to reduce external factors. Integrating mangrove forest areas like cultivation, silvofishery, ecotourism areas; involving local communities, community leaders, and stakeholders in planning, implementation, evaluation, and conservation for the development ecotourism; supporting infrastructure mangrove ecotourism visitors, and together with the community in conducting innovation/diversification of management based on the utilization and conservation of mangrove resources.
Mapping Analysis of Mangrove Areas using Unmanned Aerial Vehicle (UAV) Method in Maros District South Sulawesi
Authors: Arfan A , Nyompa S , Maru R , Nurdin S , Juanda M F
Published: December 2021

Unmanned Aerial Vehicle (UAV) technology can be used for remote sensing applications. The use of UAVs increases the efficiency of collecting land use information in mangrove forest areas. The purpose of the study was to analyze the mangrove forest area using an Unmanned Aerial Vehicle around Sabang Tambua Pier and Ampekale Village. The data analysis technique is remote sensing analysis and geographic information system using Pix4D, Agisoft Metashape 1.7 and ArcGIS ArcMap 1.4 applications. The results of the analysis show that mangroves appear green in color, rough texture, elongated shape following the coastline. Residential settlements are white or brown in color, rectangular in shape, rough in texture and the site sometimes follows the highway and follows the coastline. The clear green pond resembles a body of water with a rectangular shape. The road segment is in the form of black lines on asphalt roads and grayish-white on concrete roads. The area of land use for mangroves, settlements, ponds, bodies of water (sea) around the Sabang Tambua Pier is 4.67 ha, 1.20 ha, 26.73 ha and 3.85 ha, while in Ampekale Village 4.06 h2, 1.95 ha, 12.61 ha and 2.10 ha.
Analysis and Simulation of SIPA Model for HIV-AIDS Transmission
Authors: Sanusi Wahidah , Annas Suwardi , Pratama Muh. Isbar , Rifandi Muh. , Irwan
Published: December 2021

The aims of this study are: to build a SIPA model on the spread of HIV/AIDS; analyse and simulation of SIPA model and to predict the spread of HIV/AIDS. An applied mathematics for Analysis of the SIPA model in case of HIV/AIDS spreading using the Jacobi matrix method to obtain eigenvalues in two conditions, namely endemic and disease-free, while the simulation model uses Maple with initial value data in the form of assumptions represented in research. The research result are the mathematical SIPA model of HIV/AIDS spreading which is a system of differential equations. The analysis of the model gives the value of the disease-free equilibrium point and the asymptotically stable endemic equilibrium point. The results also found that the basic reproduction number was R0=0.0067 for disease-free conditions and R0=2.7944 for endemic conditions indicating the condition of HIV/AIDS spreading cases in the population. The simulation results found that there is a very significant difference between the numbers of AIDS populations when free from disease and during endemic conditions, so that attention is needed for the government to be able to tackle the spread of HIV/AIDS.
Integral Estimator with Kernel Approach for Estimating Nonparametric Regression Functions
Authors: Hidayat Rahmat , Ma’rufi  , Yuliani
Published: December 2021

Derivatives are measurements of how a function change as the input value changes, or in general a derivative shows how one quantity changes due to a change in another quantity. The concept of universal or comprehensive function derivatives is widely used in various scientific fields. For example, in economics, people are interested in studying the condition of the derivative of an objective function as the result of an optimization problem. In this study, nonparametric procedures are used to estimate a function where the form of the function does not lead to a particular function model. Suppose we are given a nonparametric regression model where f is an unknown function. The main problem of regression analysis is to determine the form of estimation f. To determine the estimation of f, one approach that can be used is the integral estimator with the Gaussian Kernel approach. Furthermore, as an application, the Labour Force Participation Rate (y) data is used with the predictor variable, namely the Average Length of Schooling (x). By using the GCV (Generalized Cross Validation) method, the optimal bandwidth is obtained at h = 80 with a GCV value of 0.243 with an MSE value of 32.1864.
Monte Carlo Simulation in Quantile Regression Parameter for Sparsity Estimate
Authors: Hapsery A , Tribhuwaneswari A B
Published: December 2021

Monte Carlo is a method used to generate data according to the distribution and resampling until the parameters of the method used became convergen. The purpose of this simulation is first to prove that quantile regression with the estimated sparsity function parameter can model the data according to the non-uniform distribution of the data. Secondly, it’s to prove that the quantile regression is a developed method from the linear regression. The pattern of data which is not uniform is generally referred to as heterogeneous data, while the pattern of uniform data distribution is called homogeneous data. Data in this study will be generated for small and large samples on homogeneous and heterogeneous data. Uniformity of variance will be carried out on both heterogeneous and homogeneous data types, namely 0.25,1 and 4. The parameter estimation process and data generation will be resampled 1000 times. Thus, in conclusion of the simulation studies was the parameter estimates in the classical regression will be the same as the parameter estimates in the quantile regression at quantile 0.5. In the simulation, it is decided that the quantile regression method can be used on heterogeneous and homogeneous data to the unconstrained number of samples and variances.
Count Regression Models for Analyzing Crime Rates in The East Java Province
Authors: Handayani Dian , Artari A F , Safitri W , Rahayu W , Santi V M
Published: December 2021

Crime rate is the number of reported crimes divided by total population. Several factors could contribute the variability of crime rates among areas. This study aims to model the relationship between crime rates among regencies and cities in the East Java Province (Indonesia) and some potentially explanatory variables based on Statistics Indonesia publication in 2020. The crime rate in the East Java Province was consistently at the top three after DKI Jakarta and North Sumatra during 2017 to 2019. Therefore, it is interesting for us to study further about the crime rate in the East Java. Our preliminary analysis indicates that there is an overdispersion in our sample data. To overcome the overdispersion, we fit Generalized Poisson and Negative Binomial regression. The ratio of deviance and degree of freedom based on Negative Binomial is slightly smaller (1.38) than Generalized Poisson (1.99). The results indicate that Negative Binomial and Generalized Poisson regression, compared to standard Poisson regression, are relatively fit to model our crime rate data. Some factors which contribute significantly (α=0.05) for the crime rate in the East Java Province under Negative Binomial as well as Generalized Poisson regression are percentage of poor people, number of households, unemployment rate, and percentage of expenditure.
Implementation of Reflective Thinking Process Approach to Students’ Mathematical Critical Thinking
Authors: Saputra Edy , Zulmaulida Rahmy
Published: December 2021

This study aims to measure students’ mathematical critical thinking skills after learning by using a reflective thinking process approach. An experimental research method with a quantitative approach was used in this research. The research design used was a One-Shot Case Study with a pre-test. The population in this study was students of Junior high school in central Aceh, meanwhile the sample was students of class VII2 of Junior high school in central Aceh with consideration of heterogeneous students’ abilities selected by purposive sampling. A mathematical critical thinking test instrument and a student’s attitude scale questionnaire were applied for the data collection of this study. The results of the research showed; (1) the improvement of students’ mathematical critical thinking skills who get learning using a reflective thinking process approach was better than learning without a reflective thinking approach; (2) the reflective thinking approach had an effect of 53.6% on increasing students’ critical thinking skills; (3) students showed a positive attitude towards learning mathematics, and also towards mathematical critical thinking questions.
Professional Teachers using Technological Pedagogical Mathematics Knowledge, are Mathematics Pre-Service Teachers Ready?
Authors: Wijaya Tommy Tanu , Ning Yimin , Salamah Umi , Hermita Neni
Published: December 2021

In today’s information age, the informatization of education requires teachers to become a new type of teacher with information capabilities. The subject teaching knowledge of integrated technology is the knowledge basis for the professionalization of teachers in the information age. This research aims to analyze Pre-service teachers’ perception of Technological, Pedagogical, and Mathematical knowledge. This research adopts the case study method, using Questionnaires for data collection tools. The sample of this research is 84 pre-service teachers from Guangxi Normal University, China. The respondents are undergraduate and master students that are chosen randomly. The instrument used is 20 questionnaire items on pre-service teachers’ perception of their TPMK ability. The data was processed by using SPSS and Microsoft Excel. The research result shows that pre-service teachers have a good Technological Pedagogical Mathematical Knowledge ability but their Technological knowledge is still lacking. Teacher education programs should provide pre-service teachers with opportunities to develop TPMK to integrate technology into teaching effectively.
Flow characterization in an axial micro-hydroturbine model
Authors: Suslov D A , Shtork S I , Litvinov I V , Gorelikov E U
Published: December 2021

The flow characteristics behind the runner of an air model of a propeller-type micro-hydroturbine were studied in detail by varying the operation conditions from part-load to high overload. The Reynolds number was varied from 3×104 to 9×104, and the swirl number from 0.7 to -0.4. An automated laser-Doppler anemometer (LDA) system for non-contact optical diagnostics was used to perform detailed measurements of the flow field distribution, including the profiles of two components of averaged velocities and pulsations and LDA signal spectra. Based on the results, a correlation was found between the identified features of the development of the flow structure under changing operating conditions of the hydroturbine and the nature of the evolution of the integral swirl number, which determines the state of the swirling flow. This can be used to develop recommendations for expanding the range of regulation of hydroturbine operation while maintaining high efficiency.
High-speed PIV investigation of the flow created by the model rotor in hover mode
Authors: Kopiev V F , Zaytsev M Yu , Kopiev V A
Published: December 2021

A study of the instantaneous and average velocity and vorticity fields in the flow created by the model helicopter rotor in the hover mode was carried out. The velocity fields of the flow generated by the model rotor were obtained by a two-dimensional TR PIV system, which provided two components of the velocity vector in the diagnostic light plane. The processing of the obtained raw images was carried out using a two-frame algorithm with adaptive interrogation windows. The experiments carried out have shown the possibility of using the PIV technique to visualize the tip vortex structure descending from the rotor blade. This possibility seems to be especially interesting as one of the means of validation of the numerical methods for calculating rotor aerodynamics and acoustics.
Optical diagnostics of hydrogen-air diffusion flame
Authors: Arbuzov V A , Arbuzov E V , Dubnishchev Yu N , Zolotukhina O S , Lukashov V V
Published: December 2021

Work motivation – adaptation of optical Hilbert diagnostic methods for visualization and study of optical density and phase temperature fields in the structure of an axisymmetric diffusion hydrogen-air flame. The diagnostic complex is implemented on the basis of the IAB-451 device with modified blocks of optical filtering, information source and processing. A laminar jet flame H2/N2
in still air is considered. The investigated torch is oriented vertically. Visualization of phase disturbances induced by the medium under study in a multi-wavelength probing (λ1 = 636 nm, λ2 = 537 nm and λ3 = 466 nm) light field is performed using polychromatic Hilbert and Foucault-Hilbert transformations in combination with registration and pixel-by-pixel processing of the dynamic RGB image structure. The dynamic phase structure of the diffusion flame is visualized. The initial temperature approximation, based on the assumption of an air mixture, is corrected so that the calculated hilbertogram matches the measured one as closely as possible. The data obtained are in good agreement with the results of thermocouple measurements. The temperature was recorded by thermocouples at reference points. The phase function is reconstructed in axisymmetric sections from RGB-hilbertograms. The reliability of the results is confirmed by comparing the experimentally obtained hilbertograms and hilbertograms reconstructed from phase structures using the Abel transform.
Comparison of experimental and theoretical results of airflow around two rough surfaces at different speeds
Authors: Thu Win , Ilin D V , Skornyakova N M
Published: December 2021

The aim of the work is to determine the effect of a rough surface on the airflow flowing around it, depending on the degree of roughness of this surface. Experimental visualization of the flow of air around samples with various rough surfaces is carried out. The experimental results are compared with the theoretical results obtained as a result of modeling this process based on the RANS system of equations.
Calculation of contrast for computer simulated resolution chart image
Authors: Kachurin Yu Yu , Kryukov A V , Kananykhin O A , Fedorinov A V
Published: December 2021

The work is devoted to the analysis of the resolution chart image created with the Image Simulation mode of ZEMAX software. The changes in image quality are simulated using the model of Helios-44M-4 photographic objective lens. The research is conducted for monochromatic light conditions and computer simulated resolution test chart as an object for the lens with different chart positions. An axial beam and an off-axis beam that corresponds to the maximum object space field angle are analyzed. The calculation of contrast of the simulated resolution chart images is made modeling different spatial frequencies of the chart lines. The contrast is calculated in three ways. The first way uses the maximum and minimum values of the image illumination, and the second and third ways are based on the integral values of the illumination of black and white lines, calculated with the method of rectangles and the method of trapeziums, respectively. Having been calculated the values of contrast are compared with the theoretical values of the diffraction modulation transfer function obtained with ZEMAX.