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This paper aims to propose and demonstrate a simple fiber optic sensor using a tapered plastic multimode fiber as a probe for measurement of calcium nitrate concentrations in de-ionized water.

The working mechanism is based on the observed increment in the transmission of the sensor that is immersed in calcium nitrate solution of higher concentration. The tapering of the plastic fiber is carried out by etching method using acetone, sand paper and de-ionized water.

Tapered fiber with diameter 0.45 mm gives the highest sensitivity of 0.028 mV/% due to better interaction between the evanescent field and the calcium nitrate solution with a good slope linearity of more than 98 per cent for a 1.07 per cent limit of detection in a straight probe arrangement. The use of calcium and nitrate ions within the sensing medium demonstrates the strong dependency of the sensor output trend on the electrolytic nature of the chemical solutions.

Demonstration of tapered plastic multimode fiber sensor probe for measurement electrolytic chemical solutions.

The purpose of this paper is to investigate, theoretically and experimentally, a concave mirror‐based fiber optic displacement sensor performance for three‐axes directional measurements.

Mathematical model is constructed based on spherical mirror properties of the concave mirror and the simulated result is found to be in good agreement with the experimental results.

Both theoretical and experimental results show that the focal length and radius of the concave mirror make significant influence to the displacement response. In the x‐axes measurement, six linear slopes are obtained with four of them are located in the vicinity of the position, two times of the focal length. The maximum measurement range of about 20 mm is obtained using a focal length of 10 mm. In the y‐ and z‐axes displacement measurements, the linear range increases as the diameter of concave mirror increases. The longest linear range of 8 mm is achieved at mirror radius of 10 mm.

This is the first demonstration of three axes directional displacement measurements using a concave mirror as a target

The purpose of this paper is to investigate, theoretically and experimentally the performance of liquid refractive index sensor (LRIS).

The proposed LRIS is based on the intensity modulation and a bundle fiber. The mathematical model is used to study the effect of inclination angle on performance of the sensor.

The theoretical result shows that the highest sensitivity can be achieved by using a probe inclined with angle 20° which is almost 13 times higher than that of 0° inclination. In the experiment, three different liquids: isopropyl alcohol, water and methanol are used to investigate the sensor response. Both theoretical and experimental results show that the peak power and the location of the displacement curve changes with refractive index. The sensitivities are obtained at 0.11/mm and 0.04/mm for the sensors with 10° and 0° inclination angles, respectively.

In this paper, a simple LRIS is proposed using a bundle fiber as a probe at various inclination angles.

The purpose of this paper is to demonstrate a simple design of a fiber optic displacement sensor using a multimode plastic fiber coupler based on reflective intensity modulation technique.

The performances of this sensor are investigated by correlating the detector output with different light sources, coupling ratios and various real objects with different reflectivity properties namely aluminum, brass and copper. In contrast to the output profile produced by probes with multiple fibers placed adjacently together, this sensor uses only one fiber for sending and receiving the light and therefore only the back slope exists.

Aluminum exhibit the highest performance among the real objects when coupled with a red He‐Ne laser and a coupling ratio of 50:50 with a sensitivity, linear range, resolution and dynamic range of 1.7 mV/mm, 1.5 mm, 16 μm, and 5.0 mm, respectively.

This is the first demonstration of a fiber optic displacement sensor using fiber coupler probe with successful examination of the correlation between the detector output, variation in coupling ratios and reflectivity properties of the tested real objects.

The purpose of this paper is to propose and demonstrate a simple yet accurate optical fibre based sensor capable of performing micron and sub‐micron thickness measurement.

The proposed sensor consists of a multimode plastic probe, three He‐Ne lasers and translation stages along with a silicon photodiode and a lock‐in amplifier to measure the output voltage as the displacement of the sensor is increased.

The system operating with a source wavelength of 633 nm can provide measurements of up to 3 μm with a sensitivity of 0.0054 mV/μm.

The thickness of the sample can be obtained from a linear equation correlating the thickness of the sample to the displacement of the sensor at which the peak output voltage is obtained, or by correlating the thickness of the sample directly to the peak output voltage measured.

A simple tapered plastic optical fiber (POF) sensor is proposed and demonstrated for measurement of uric acid concentrations in de-ionized water. The paper aims to discuss these issues.

The sensor operates based on intensity modulation technique as the tapered POF probe which was coated by a single walled carbon nonotubes polyethylene oxide (SWCNT-PEO) composite is immersed into the uric acid solution. The probe was fabricated using an etching method and has a waist diameter of 0.46 mm and tapering length of 10 mm.

As the concentration varies from 0 to 500 ppm, the output voltage of the sensor increases linearly from 6.13 to 7.35 mV with a sensitivity of 0.0023 mV/% and a linearity of more than 97.20 percent. The SWCNT-PEO composite coating increases the sensitivity of the proposed sensor due to the effective cladding refractive index, which increases with the coating and thus allows more light to be transmitted from the tapered fiber.

This is the first demonstration of the tapered POF sensor for measurement of uric acid concentrations in de-ionized water.

Although many researchers have widely studied additive manufacturing (AM) as one of the most important industrial revolutions, few have presented a bibliometric analysis of the published studies in this area. This paper aims to evaluate AM research trends based on 4607 publications most cited from year 2010 to 2020.

The research methodology is bibliometric indicators and network analysis, including analysis based on keywords, citation analysis, productive journal, related published papers and authors indicators. Two free available software were employed VOSviewer and Bibexcel.

Keywords analysis results indicate that among the AM processes, Selective Laser Melting and Fused Deposition Modeling techniques, are the two processes ranked on top of the techniques employed and studied with 35.76% and 20.09% respectively. The citation analysis by VOSviewer software, reveals that the medical applications field and the fabrication of metal parts are the areas that interest researchers greatly. Different new research niches, as pharmaceutical industry, digital construction and food fabrication are growing topics in AM scientific works. This study reveals that journals “Materials & design”, “Advanced materials”, “Acs applied materials & interfaces”, “Additive manufacturing”, “Advanced functional materials” and “Biofabrication” are the most productive and influential in AM scientific research.

The results and conclusions of this work can be used as indicators of trends in AM research and/or as prospects for future studies in this area.

This study aims to propose and study a refractive index sensor based on measuring variations of the internal diffuse reflectance from a glass interface in a functional design. The device is uncomplicated to assemble with simple optical elements and it can be built as a robust and stable sensor.

This study presents a simplified theoretical model of the signal obtained with the proposed device and perform a detailed analysis of its potential resolution and merits.

The authors report proof-of-principle experiments with a home-made device to evaluate its performance as a refractometer and index of refraction sensor.

The main novelty of the device is the use of a diffusing surface to couple light into a glass plate with a wide range of angles of refraction, including angles larger than the critical angle with the external medium, and using the same diffusing surface to couple reflected light out of the glass plate, including light that suffered total internal reflection.

Selective laser melting and electron beam melting processes are well-known for the additive manufacturing of metal parts. Metal powder bed fusion (MPBF) is a common term for them. The MPBF process can empower the manufacturing of intricate shapes by reducing the use of special tools, shortening the supply chain and allowing small batches. However, the MPBF process suffers from many quality issues. In literature, several works are recorded for qualification of the MPBF part. The purpose of this study is to recollect those works done for quality control and report their helpful findings for further research and development.

A systematic literature review was conducted to highlight the major quality issues in the MPBF process and its root causes. Further, the works reported in the literature for mitigation of these issues are classified and discussed in five categories: experimental investigation, finite element method-based numerical models, physics-based analytical models, in-situ control using artificial intelligence (AI) and machine learning (ML) methods and statistical approaches. A comparison is also prepared among these strategies based on their suitability and limitations. Additionally, improvements in MPBF printers are pointed out to enhance the part quality.

Analytical models require less computational time to simulate the MPBF process and need a smaller number of experiments to confirm the results. They can be used as an efficient process parameter planning tool to print metal parts for noncritical applications. The AI-ML based quality control is also suitable for MPBF processes as it can control many processing parameters that may affect the quality of the MPBF part. Moreover, capabilities of MPBF printers like thinner layer thickness, smaller beam diameter, multiple lasers and high build temperature range can help in quality control.

This study converts the piecemeal data on MPBF part qualification methods into interesting information and presents it in tabular form under each strategy. This tabular information provides the basis for further quality improvement efforts in the MPBF process.

This study references researchers and practitioners on recent quality control efforts and their significant findings for a better quality of MPBF part.

This paper aims to study multiobjective genetic algorithm ability in determining the process parameter and postprocess condition that leads to maximum relative density (RD) and minimum surface roughness (Ra) simultaneously in the case of a Ti6Al4V sample process by laser beam powder bed fusion.

In this research, the nondominated sorting genetic algorithm II is used to achieve situations that correspond to the highest RD and the lowest Ra together.

The results show that several situations cause achieving the best RD and optimum Ra. According to the Pareto frontal diagram, there are several choices in a close neighborhood, so that the best setup conditions found to be 102–105 watt for laser power followed by scanning speed of 623–630 mm/s, hatch space of 76–73 µm, scanning patter angle of 35°–45° and heat treatment temperature of 638–640°C.

Suitable selection of process parameters and postprocessing treatments lead to a significant reduction in time and cost.