Smart scientific instruments based on smartphones: a brief review

Smartphone has gone beyond a communication hub to be a measurement device itself, thanks to various built-in sensors. This article reviewed achievements in transforming ubiquitous smartphones into cost-effective scientific instruments for educational laboratories, environmental studies, point-of-care diagnostics, home-based health monitoring, and rehabilitation. Magnetic fields were precisely measured by built-in magnetometers, leading to demonstrations for engineering and medical applications. The smartphone-based joint-angle measurement was a viable alternative to traditional goniometers. Characterizations of optical signals captured by cameras led to portable spectrophotometers and colorimeters for both educational and practical uses. Interestingly, smartphones became a platform for high-resolution microscopes and fluorescence microscopes were developed with add-on components. These smart instruments become even more attractive options in the pandemic period with limited facility and laboratory access

Modernizing Batik Clothes for Community Enterprises Using Creative Design and Colorimetry

The objective of this study was to modernize batik clothes, a cultural heritage of Southeast Asia, through creative design, color characterization, and collection presentation. Three community enterprises from the southern regions of Thailand participated in designing batik motifs based on their local identities. The pattern of the first manufacturer group was influenced by stones and ancient beads of vivid orange and blue shades. The second community was inspired by the nearby sea, resulting in ocean blue, white, and emerald green colors on batik fabrics. Floras in the south of Thailand dominated the design of the final manufacturer group. Smartphone colorimetry was then used to characterize the batik fabrics. It was demonstrated that this proposed color quantification was not confined to the laboratory, and could easily be carried out by vendors or customers. The collaboration encouraged local batik artisans to use a variety of inspirations, new tools, as well as professional design and production methods. To introduce modernized batik to the public, collections of these newly designed clothes were displayed in a fashion show staged under the theme “Southern Chic.” The presentation of Thai batik clothes in seasonal collections highlighted the transformations of local manufacturers and products with increasing appeal to younger people. In addition to conservation and commercial advantages, the modernized approach is accessible and attractive for education purposes, engaging students in cultural heritage. Doi: 10.28991/esj-2021-01319 Full Text: PD

Comparison of closed-form solutions to experimental magnetic force between two cylindrical magnets

The force between permanent magnets implemented in many engineering devices remains an intriguing problem in basic physics. The variation of magnetic force with the distance x between a pair of magnets cannot usually be approximated as x-4 because of the dipole nature and geometry of magnets. In this work, the force between two identical cylindrical magnets is accurately described by a closed-form solution. The analytical model assumes that the magnets are uniformly magnetized along their length. The calculation, based on the magnetic field exerted by one magnet on the other along the direction of their orientation, shows a reduction in the magnetic force with the distance x and a dependence on the size parameters of magnets. To verify the equation, the experiment was set up by placing two cylindrical neodymium iron boron type magnets in a vertical tube. The repulsive force between the identical upper and lower magnets of 2.5 cm in diameter and 7.5 cm in length was measured from the weight on the top of the upper magnet. The resulting separation between the magnets was recorded as x. The forces measured at x=0.004-0.037 m differ from the values calculated using the analytic solution by -0.55 % to -13.60 %. The calculation also gives rise to a practical remnant magnetic field of 1.206 T. When x is much large than the equation of force is approximated as a simple form proportional to 1/x-4. The finding can be directly used in magnetic levitation as well as applied in calculating magnetic fields and forces in other systems incorporating permanent magnets

Comparative analysis of Tesseract and Google Cloud Vision for Thai vehicle registration certificate

Optical character recognition (OCR) is a technology to digitize a paper-based document to digital form. This research studies the extraction of the characters from a Thai vehicle registration certificate via a Google Cloud Vision API and a Tesseract OCR. The recognition performance of both OCR APIs is also examined. The 84 color image files comprised three image sizes/resolutions and five image characteristics. For suitable image type comparison, the greyscale and binary image are converted from color images. Furthermore, the three pre-processing techniques, sharpening, contrast adjustment, and brightness adjustment, are also applied to enhance the quality of image before applying the two OCR APIs. The recognition performance was evaluated in terms of accuracy and readability. The results showed that the Google Cloud Vision API works well for the Thai vehicle registration certificate with an accuracy of 84.43%, whereas the Tesseract OCR showed an accuracy of 47.02%. The highest accuracy came from the color image with 1024×768 px, 300dpi, and using sharpening and brightness adjustment as pre-processing techniques. In terms of readability, the Google Cloud Vision API has more readability than the Tesseract. The proposed conditions facilitate the possibility of the implementation for Thai vehicle registration certificate recognition system

Automated Data Digitization System for Vehicle Registration Certificates Using Google Cloud Vision API

This study aims to develop an automated data digitization system for the Thai vehicle registration certificate. It is the first system developed as a web service Application Programming Interface (API), which is essential for any enterprise to increase its business value. Currently, this system is available on “www.carjaidee.com”. The system involves four steps: 1) an embedded frame aligns a document to be correctly recognised in the image acquisition step; 2) sharpening and brightness filtering techniques to enhance image quality are applied in the pre-processing step; 3) the Google Cloud Vision API receives a prompt to proceed in the recognition step; 4) a specific domain dictionary to improve accuracy rate is developed for the post-processing step. This study defines 92 images for the experiment by counting the correct words and terms from the output. The findings suggest that the proposed method, which had an average accuracy of 93.28%, was significantly more accurate than the original method using only the Google Cloud Vision API. However, the system is limited because the dictionaries cannot automatically recognise a new word. In the future, we will explore solutions to this problem using natural language processing techniques. Doi: 10.28991/CEJ-2022-08-07-09 Full Text: PD

Fast Color Quantization Using Weighted Sort-Means Clustering

Color quantization is an important operation with numerous applications in graphics and image processing. Most quantization methods are essentially based on data clustering algorithms. However, despite its popularity as a general purpose clustering algorithm, k-means has not received much respect in the color quantization literature because of its high computational requirements and sensitivity to initialization. In this paper, a fast color quantization method based on k-means is presented. The method involves several modifications to the conventional (batch) k-means algorithm including data reduction, sample weighting, and the use of triangle inequality to speed up the nearest neighbor search. Experiments on a diverse set of images demonstrate that, with the proposed modifications, k-means becomes very competitive with state-of-the-art color quantization methods in terms of both effectiveness and efficiency.Comment: 30 pages, 2 figures, 4 table

In vitro bioactivity and stem cells attachment of three-dimensionally ordered macroporous bioactive glass incorporating iron oxides

Three-dimensionally ordered macroporous bioactive SiO2-CaO-Na2O-P2O5 glass (3DOM-BG) is synthesized by using the sol-gel method. After an in vitro test in simulated body fluid (SBF), the hydroxyapatite (HAp) crystalline phase is clearly formed on its surface as confirmed by X-ray diffractometry (XRD) and Raman spectroscopy. Magnetic 3DOM-BG/Fe samples are synthesized by partial substitution of SiO2 with iron oxide. Whilst the HAp layer is not confirmed, energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and XRD analysis reveal calcium phosphate layer on the surface of 3DOM-BG/Fe samples after the SBF soaking. The growth of HAp-like layer is slower with increasing iron oxides. The initial mechanism that thought to induce bone formation is reduced due to the replacement of Ca2+ with Fe ions in the glass network. The formation of HAp-like layer is modified by the sedimentation of Ca and P while the nonmagnetic 3DOM-BG forms the calcium phosphate by the ionic exchange following the Hench mechanism. The adult human adipose tissue-derived stem cells (hADSCs) can be closely attached and well spread on the flat-plate of all 3DOM-BG/Fe and 3DOM-BG. Without detectable cytotoxicity possibly induced by iron oxides, the osteoblast can be grown and proliferated. In addition to these bioactivity and biocompatibility, porous structures can allow their possible use in targeted drug delivery and magnetic properties of 3DOM-BG/Fe can essentially be implemented in hyperthermia therapy

Improving the Performance of K-Means for Color Quantization

Color quantization is an important operation with many applications in graphics and image processing. Most quantization methods are essentially based on data clustering algorithms. However, despite its popularity as a general purpose clustering algorithm, k-means has not received much respect in the color quantization literature because of its high computational requirements and sensitivity to initialization. In this paper, we investigate the performance of k-means as a color quantizer. We implement fast and exact variants of k-means with several initialization schemes and then compare the resulting quantizers to some of the most popular quantizers in the literature. Experiments on a diverse set of images demonstrate that an efficient implementation of k-means with an appropriate initialization strategy can in fact serve as a very effective color quantizer.Comment: 26 pages, 4 figures, 13 table

Using a smartphone acceleration sensor to study uniform and uniformly accelerated circular motions

The acceleration sensor of a smartphone is used for the study of the uniform and uniformly accelerated circular motions in two experiments. Data collected from both experiments are used for obtaining the angular velocity and the angular acceleration, respectively. Results obtained with the acceleration sensor are shown to be in good agreement with alternative methods, like using video recordings of both experiments and a physical model of the second experiment.Castro-Palacio, JC.; Velazquez, L.; Gómez-Tejedor, JA.; Manjón Herrera, FJ.; Monsoriu Serra, JA. (2014). Using a smartphone acceleration sensor to study uniform and uniformly accelerated circular motions. Revista Brasileira de Ensino de Fisica. 36(2):2315-2315. doi:10.1590/S1806-11172014000200015S2315231536

Recent Developments in 3D Printing of Rare-Earth-Free Permanent Magnets

This article reviews the advances in additive manufacturing of magnetic ceramics and alloys without rare-earth elements. Near-net-shaped permanent magnets with varying shapes and dimensions overcome traditional limitations of the cast, sintered, and bonded magnets. The published articles are categorized based on material types and 3D printing techniques. Selective laser melting and electron beam melting were predominantly used to produce alnico magnets. In addition to the electron beam melting, manganese aluminium-based alloys were successfully printed by fuse filament fabrication. By incorporating magnetic powders in polymers and then printing via extrusion, the fuse filament fabrication was also used to produce strontium ferrite magnets. Moreover, hard ferrites were printed by stereolithography and extrusion free-forming, without drawing composites into filaments. Magnetic properties in some cases are comparable to those of conventional magnets with the same compositions. Currently, available software packages can simulate magnetic fields for designing magnets and optimize the integration in electrical machines. These developments open up opportunities for next-generation permanent magnet applications