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Number of results: 14
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Abstract

Abstract The purpose of this paper is to present a multichannel ultrasonic range finder which was designed for the navigation system for blind people. A substantial number of consultations with blind people in the Blind People Centre in Krakow have shown that the navigation and obstacle detection with a help of a white stick only, is not sufficient enough to assure a high safety level. Electronic aids which are being designed for blind people should be mobile, comfortable and low-powered. That is why the MOBIAN© (a mobile safety system for the blind) project is being carried out by the authors to create a highly reliable safety navigation system for blind people. It could not only improve blind people quality of life but also their safety, especially when they are walking in unknown areas. As a part of this project, the multichannel ultrasonic range finder was designed, produced and tested. The tests have proven the device is capable of detecting objects from different directions in a range over 4 m. The device interface is easy to manage and can be controlled by almost any microcontroller or FPGA chip. The designed range finder is to be implemented in the electronic assistant project for blind people. Other systems, including the industrial ones, for instance, mobile robots or gates that count people entries, could benefit from this multichannel range finder. Usually, some low-cost ultrasonic range finders use two transducers for each channel (a transmitter and a receiver). The designed device employs only one transducer per channel which minimizes the end-device size and cost and at the same time provides with the main functionality. Novelty of this device is its multichannel design and the emplacement of the ultrasonic transducers, which can be used due to the application of the multichannel analog multiplexer. Thus, it is possible to detect obstacles, even the inclined ones, with higher reliability and increase the safety of blind people while walking. Also, this design and the transducers’ placement allow to detect obstacles much quicker, when the blind user suddenly turns.
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Authors and Affiliations

W. Gelmuda
A. Kos
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Abstract

In this article, the authors present a model and a method of determining thermal parameters of a single point of the thermal touch screen for the blind and thermal parameters of selected parts of a human hand. Blind people, by using this device can “see” a pattern of dots by feeling hot spots. The thermal touch screen for the blind was used as a calorimeter and enables to calculate the amount of heat provided to a finger at a temperature ranging from 8°C to 52°C, that is the full range of temperature detected by humans. The authors designated thermal conductivity and heat capacity of both Peltier micromodule and parts of the user's hand. Results of the presented research allow optimizing the construction of the thermal touch screen for the blind and may be helpful for thermal modelling of the human body.

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Authors and Affiliations

Krzysztof Boroń
Andrzej Kos
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Abstract

The paper analyzes the phenomenon of heat transfer and its inertia in solids. The influence of this effect on the operation of an integrated circuit is described. The phenomenon is explained using thermal analogy implemented in the Spice environment by an R-C thermal model. Results from the model are verified by some measurements with a chip designed in CMOS 0.7 μm (5 V) technology. The microcontroller-based measurement system structure and experiment results are described.

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Authors and Affiliations

Maciej Frankiewicz
Adam Gołda
Andrzej Kos
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Abstract

The compactness of dimension stone blocks was previously controlled through various methods that were partially based on personal experiences, acoustic and visual observance of materials. With the development of technology, the ultrasonic pulse method is frequently used for the examination of stone test pieces and with an analysis of acquired data through the tomography method, the compactness is determined. The monolith stone blocks that are found at a site contain hidden discontinuities. The technique of data acquisition and the use of various instruments enable a good overview of the block interior. With an increased number of measurements, a suitable classification is prepared that helps reduce modification costs and increases the quality of stone blocks. The control methodology of compactness is based on the passage of longitudinal waves through the stone block without damaging the block during control. High differences in speed show irregularities in the material. With the observation system, we can prepare a tomography of the measured profiles that show us the locations of irregularities that should be observed more closely. During in situ measurements, the data for comparison with measured results are acquired. Determination of critical locations is of extreme importance before the processing of the block into smaller stone products or during the reconstruction of older stone elements or sculptures. The purpose of “in situ” measurements is to prepare a simple and fast method for the evaluation of materials compactness and for production work.

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Authors and Affiliations

Andrej Kos
Jože Kortnik
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Abstract

This article presents a system of precise navigation for a visually impaired person which uses GPS navigation and an infrared sensor in the form of an infrared matrix. The presented system allows determining the orientation and distance of a blind person relative to a selected object, e.g. a wall or road edge. The application of the above solution facilitates a significant increase in the accuracy of determining the position of a blind person compared to the accuracy offered by commonly used ground satellite devices. The system uses thermal energy accumulated in the environment without the need to generate additional signals. The main parts of the system are a simple infrared matrix, data processing system and vibrating wristband. Messages and navigation warnings are sent to a blind person in the form of a vibration code. The article describes the method of determining the path of a specified width and distance from the wall of a building, curb, etc., along which a blind person should move. The article additionally describes the method of determining the orientation of a blind person depending on the selected object. Such a method facilitates verifying whether the visually impaired person is moving according to the indicated direction. The method can also be used to navigate mobile robots. Due to the use of natural energy for data registration and processing, the mobile navigation system can be operated for a long time without the need to recharge the battery.

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Bibliography

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  8.  P. Barański, M. Polańczyk, and P. Strumiłło, “A remote guidance system for the blind”, in Proceedings of the 12th International Conference on e-Health Networking, Application & Services (Healthcom2010), Lyon, France, 2010, pp. 386–390.
  9.  W. Gelmuda and A. Kos, “Multichannel ultrasonic range finder for blind people navigation”, Bull. Pol. Ac.: Tech. 61(3), 633‒637 (2013).
  10.  P. Marzec and A. Kos, “Low energy precise navigation system for the blind with infrared sensors”, in 2019 MIXDES – 26th International Conference “Mixed Design of Integrated Circuits and Systems”, Rzeszów, 2019.
  11.  Kiruthika and Sheela, “Developing mobile application to navigate blind people using sensors”, 2016 International Conference on Computation of Power, Energy Information and Commuincation (ICCPEIC), Chennai, 2016, pp. 080‒084, doi: 10.1109/ICCPEIC.2016.7557228.
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  14.  A. Kos, K. Boroń, and I. Brzozowski, “Thermal tablet for the blind”, Microelectron. Int. 33(1), 1‒8 (2016), doi: 10.1108/MI-02-2015- 0016.
  15.  R. Sarkar, S. Das, and D. Rudrapal, “A low cost microelectromechanical Braille for blind people to communicate with blind or deaf blind people through SMS subsystem”, 2013 3rd IEEE International Advance Computing Conference (IACC), Ghaziabad, 2013, pp. 1529‒1532, doi: 10.1109/IAdCC.2013.6514454.
  16.  R. Uzun, G.K. Yaman, A. Tekkanat, and Y. İşler, “Wristband design to support blind people”, 2017 Medical Technologies National Congress (TIPTEKNO), Trabzon, 2017, pp. 1‒4, doi: 10.1109/TIPTEKNO.2017.8238038.
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Authors and Affiliations

Paweł Marzec
1
Andrzej Kos
1

  1. AGH University of Science and Technology, Faculty of Computer Science, Electronics and Telecommunications, al. Mickiewicza 30, 30-059 Krakow, Poland
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Abstract

Robots that can comprehend and navigate their surroundings independently on their own are considered intelligent mobile robots (MR). Using a sophisticated set of controllers, artificial intelligence (AI), deep learning (DL), machine learning (ML), sensors, and computation for navigation, MR's can understand and navigate around their environments without even being connected to a cabled source of power. Mobility and intelligence are fundamental drivers of autonomous robots that are intended for their planned operations. They are becoming popular in a variety of fields, including business, industry, healthcare, education, government, agriculture, military operations, and even domestic settings, to optimize everyday activities. We describe different controllers, including proportional integral derivative (PID) controllers, model predictive controllers (MPCs), fuzzy logic controllers (FLCs), and reinforcement learning controllers used in robotics science. The main objective of this article is to demonstrate a comprehensive idea and basic working principle of controllers utilized by mobile robots (MR) for navigation. This work thoroughly investigates several available books and literature to provide a better understanding of the navigation strategies taken by MR. Future research trends and possible challenges to optimizing the MR navigation system are also discussed.
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Authors and Affiliations

Ravi Raj
1
ORCID: ORCID
Andrzej Kos
1

  1. Faculty of Computer Science, Electronics, and Telecommunications, AGH University of Science and Technology, Krakow, Poland
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Abstract

This study investigates the effects of grain boundary structures on mechanical properties of nanocrystalline Al-0.7Mg-1.0Cu alloy using nanoindentation system. Grain boundary structure transforms to high angle grain boundaries from low angle ones with increase of heat treatment temperature and the transformation temperature is about 400℃. Young’s modulus and hardness are higher in sample with low angle grain boundaries, while creep length is larger in sample with high angle ones. These results indicate that progress of plastic deformation at room temperature is more difficult in sample with low angle ones. During compression test at 200℃, strain softening occurs in all samples. However, yield strength in sample with low angle grain boundaries is higher twice than that with high angle ones due to higher activation energy for grain boundary sliding.
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Bibliography

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Authors and Affiliations

Jin Man Jang
1 2
ORCID: ORCID
Wonsik Lee
1
ORCID: ORCID
Se-Hyun Ko
1
ORCID: ORCID

  1. Korea Institute of Industrial Technology, Incheon, 21999, Republic of Korea
  2. Inha University, Department of Materials Science and Engineering, Incheon, 22212, Republic of Korea
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Abstract

A356 Al composites reinforced by short carbon fiber were prepared through the 2-step process: fabrication of a composite precursor and ultrasonication of the precursor melt. The short carbon fibers were coated with 0.15~1.5 μm thick SiC layer by a carbothermal reaction, and an amount of the carbon fiber reinforcement was determined to be 1.5 vol.% and 4.0 vol.%, respectively. The addition of the carbon fiber increased the hardness of A356 alloy. However, tensile strength did not increase in the as-cast composites regardless of the SiC coating and volume fraction of the carbon fiber, due to the debonding which reduced load transfer efficiency from matrix to fiber at the interface. After T6-treatment of the composites, a significant increase in strength occurred only in the composite reinforced by the SiC-coated short carbon fiber, which was considered to result from the formation of a precipitate improving the Al/SiC interfacial strength
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Authors and Affiliations

Jin Man Jang
1
ORCID: ORCID
Se-Hyun Ko
1
ORCID: ORCID
Wonsik Lee
1
ORCID: ORCID

  1. Advanced Materials and Process R&D Department, Korea Institute of Industrial Technology, Incheon 21999, Republic of Korea
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Abstract

The present research deals with the effect of pre-strain on the hydrogen embrittlement behavior of intercritically annealed medium-Mn steels. A slow strain-rate tensile test was conducted after hydrogen charging by an electrochemical permeation method. Based on EBSD and XRD analysis results, the microstructure was composed of martensite and retained austenite of which fraction increased with an increase in the intercritical annealing temperature. The tensile test results showed that the steel with a higher fraction of retained austenite had relatively high hydrogen embrittlement resistance because the retained austenite acts as an irreversible hydrogen trap site. As the amount of pre-strain was increased, the hydrogen embrittlement resistance decreased notably due to an increase in the dislocation density and strain-induced martensite transformation.
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Authors and Affiliations

Sang-Gyu Kim
1
ORCID: ORCID
Young-Chul Yoon
1
ORCID: ORCID
Seok-Woo Ko
1
ORCID: ORCID
Byoungchul Hwang
1
ORCID: ORCID

  1. Seoul National University of Science and Technology, Department of Materials Science and Engineering, Seoul, 01811, Republic of Korea
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Abstract

Dual-band infrared detector, which acquires more image information than single-band detectors, has excellent detection, recognition, and identification capabilities. The dual-band detector can have two bumps to connect with each absorber layer, but it is difficult to implement small pitch focal plane arrays and its fabrication process is complicated. Therefore, the most effective way for a dual-band detector is to acquire each band by bias-selectable with one bump. To aim this, a dual-band MWIR/LWIR detector based on an InAs/GaSb type-II superlattice nBn structure was designed and its performance was evaluated in this work. Since two absorber layers were separated by the barrier layer, each band can be detected by bias-selectable with one bump. The fabricated dual-band device exhibited the dark current and spectral response characteristics of MWIR and LWIR bands under negative and positive bias, respectively. Spectral crosstalk that is a major issue in dual-band detectors was also improved. Finally, a 20 μm pitch 640 × 512 dual-band detector was fabricated, and both MWIR and LWIR images exhibited an average noise equivalent temperature difference of 30 mK or less at 80 K.
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Authors and Affiliations

Hyun-Jin Lee
1
ORCID: ORCID
Jun Ho Eom
1
Hyun Chul Jung
1
Ko-Ku Kang
1
Seong Min Ryu
1
Ahreum Jang
1
Jong Gi Kim
1
Young Ho Kim
1
Han Jung
1
Sun Ho Kim
2
Jong Hwa Choi
2

  1.  i3system, Inc., 26-32, Gajeongbuk-ro, Yuseong-gu, Daejeon, 34113, Republic of Korea
  2. Agency of Defense Development, 34186 P.O.Box 35, Yuseong-gu, Daejeon, Republic of Korea
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Abstract

In-situ study on the high-temperature fracture behaviour of 347 stainless steel was carried out by using a confocal laser scanning microscope (CLSM). The welding microstructures of the 347 stainless steel were simulated by subjecting the steel specimen to solution and aging treatments. Undissolved NbC carbides were present within grains after solution treatment, and M23C6 carbides were preferentially formed at grain boundaries after subsequent aging treatment. The M23C6 carbides formed at grain boundaries worked as stress concentration sites and thus generated larger cracks during high-temperature tensile testing. In addition, grain boundary embrittlement was found to be a dominant mechanism for the high-temperature fracture of the 347 stainless steel because vacancy diffusion in the Cr-depleted zones enhances intergranular fracture due to the precipitation of M23C6 carbides at grain boundaries.
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Authors and Affiliations

Seok-Woo Ko
1
ORCID: ORCID
Hyeonwoo Park
2
ORCID: ORCID
Il Yoo
3
ORCID: ORCID
Hansoo Kim
2
ORCID: ORCID
Joonho Lee
2
ORCID: ORCID
Byoungchul Hwang
1
ORCID: ORCID

  1. Seoul National University of Science and Technology, Department of Materials Science and Engineering, 232 Gongneung-ro, Nowon-gu, Seoul 01811, Republic of Korea
  2. Korea University, Department of Materials Science and Engineering, Seoul 02841, Republic of Korea
  3. ADNOC LNG, Abu Dhabi, United Arab Emirates
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Abstract

In this study, we demonstrated a method of controllably synthesizing one-dimensional nanostructures having a dense or a hollow structure using fibrous sacrificial templates with tunable crystallinity. The fibrous Ga2O3 templates were prepared by calcining the polymer/gallium precursor nanofiber synthesized by an electrospinning process, and their crystallinity was varied by controlling the calcination temperature from 500oC to 900oC. GaN nanostructures were transformed by nitriding the Ga2O3 nanofibers using NH3 gas. All of the transformed GaN nanostructures maintained a one-dimensional structure well and exhibited a diameter of about 50 nm, but their morphology was clearly distinguished according to the crystallinity of the templates. When the templates having a relatively low crystallinity were used, the transformed GaN showed a hollow nanostructure, and as the crystallinity increased, GaN was converted into a denser nanostructure. This morphological difference can be explained as being caused by the difference in the diffusion rate of Ga depending on the crystallinity of Ga2O3 during the conversion from Ga2O3 to GaN. It is expected that this technique will make possible the tubular nanostructure synthesis of nitride functional nanomaterials.
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Authors and Affiliations

Yun Taek Ko
1
ORCID: ORCID
Mijeong Park
2
ORCID: ORCID
Jingyeong Park
1
ORCID: ORCID
Jaeyun Moon
3
ORCID: ORCID
Yong-Ho Choa
1
ORCID: ORCID
Young-In Lee
2
ORCID: ORCID

  1. Hanyang University, Dept. of Advanced Materials Science and Engineering, Ansan 15588, Republic of Korea
  2. Seoul National University of Science and Technology, Dept. of Materials Science and Engineering, Seoul 01811, Republic of Korea
  3. University of Nevada , Dept. of Mechanical Engineering, Las Vegas, 4505 S. Maryland PKWY Las Vegas, Nv 89154, United States

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