bluuebunny/crossref_metadata_2025 huggingface dataset:
Vertical autofocus for the phase screen in a turbulent ionosphere
Authors: Gilman Mikhail , Tsynkov Semyon
Published: February 2023

The performance of spaceborne synthetic aperture radars (SARs) is affected by the Earth’s ionosphere. In particular, the ionospheric turbulence causes phase perturbations of the SAR signals, which may lead to image distortions. A convenient way to model those phase perturbations is by means of a phase screen. The latter is an infinitesimally thin layer positioned at a certain elevation above the Earth’s surface. The radar signal acquires an instant perturbation once its trajectory intersects the screen. The trajectory is a ray between the antenna and the target, and the magnitude of the perturbation is equal to the screen density at the intersection point. The density is a bivariate function of the coordinates along the screen. The coordinates of a specific intersection point are determined by the ray itself, as well as the screen elevation. Thus, the magnitude of the phase perturbation explicitly depends on the screen elevation. Accordingly, to compensate for the resulting image distortions one should be able to determine the elevation of the screen. In the paper, we develop an algorithm of vertical autofocus that derives this elevation from the received SAR data, given a pair of point scatterers in the target area. The proposed algorithm exploits a modification of the coherent interferometric imaging that was previously employed to reduce the effect of phase errors due to the trajectory uncertainty. In our analysis, we highlight the differences between this case and transionospheric propagation.
An ultra-high figure of merit refractive index sensor with Mie lattice resonance of a toroidal dipole in an all-dielectric metasurface array in the near-infrared
Authors: Tu Shijuan , Liu Xinxin , Liang Kunlin , Fu Qin , Wang Yuanli , Du Qingguo , Li Zhengying
Published: February 2023

Recently, improvement of the sensing performance of refractive index sensors using the weak far-field radiation and strong local field enhancement properties of toroidal dipole resonances has been intensively studied. Transmission/reflection spectra with significant narrow linewidth resonance have a vital effect in improving the sensing performance. However, a narrower linewidth always leads to smaller modulation depth of the resonance, which hinders the sensing performance to be improved for experiments. In this paper, we design an ultrathin all-dielectric asymmetric X-type metasurface array, where an extremely narrow linewidth and high modulation depth of transmission resonance in the near-infrared have been demonstrated with Mie lattice resonance formed by the coupling of the toroidal dipole with Rayleigh anomalous diffraction. With optimized structure parameters, a transmission dip with a full width at half-maximum as narrow as 0.061 nm and a modulation depth as high as 99.24% are achieved at a wavelength of 943.33 nm with a corresponding Q factor of 15464. According to the analysis of the displacement current distributions and the scattered powers in the far field at the resonant and nonresonant wavelengths, it is confirmed that the narrow linewidth resonance originates from the coupling of the toroidal dipole with Rayleigh anomalous diffraction. A sensitivity and a figure of merit of 321 nm RIU−1 and 5262 RIU−1 are numerically demonstrated respectively for a refractive index sensor based on the all-dielectric asymmetric X-type metasurface array.
Evaluation of the frequency characteristics of cntTSP measurement for unsteady low-speed flow
Authors: Ikami Tsubasa , Konishi Yasufumi , Nagai Hiroki
Published: February 2023

Carbon nanotube temperature-sensitive paint (cntTSP) is a fluid measurement technology that utilizes temperature-sensitive paint (TSP). It works as an optical temperature sensor, with a thin layer of carbon nanotubes to heat the TSP layer. This study investigated the frequency characteristics of cntTSP measurements in low-speed flow. The flow field on the flat plate was periodically changed by introducing intermittent local disturbances to the flat plate in a low-speed wind tunnel test. cntTSP measurement was conducted behind the local disturbance to evaluate changes in the temperature associated with periodic changes in the flow. The amplitude of the temperature change decreased approximately linearly with the frequency in a double-logarithmic graph. Moreover, the temperature amplitude at 25 Hz was 0.008 K, and it was necessary to detect a very small temperature change to evaluate high-frequency phenomena.
Multiple scale asymptotics of map enumeration
Authors: Ercolani Nicholas , Lega Joceline , Tippings Brandon
Published: February 2023

We introduce a systematic approach to express generating functions for the enumeration of maps on surfaces of high genus in terms of a single generating function relevant to planar surfaces. Central to this work is the comparison of two asymptotic expansions obtained from two different fields of mathematics: the Riemann–Hilbert analysis of orthogonal polynomials and the theory of discrete dynamical systems. By equating the coefficients of these expansions in a common region of uniform validity in their parameters, we recover known results and provide new expressions for generating functions associated with graphical enumeration on surfaces of genera 0 through 7. Although the body of the article focuses on 4-valent maps, the methodology presented here extends to regular maps of arbitrary even valence and to some cases of odd valence, as detailed in the appendices.
Improved Parkinsonian tremor quantification based on automatic label modification and SVM with RBF kernel
Authors: Li Yumin , Wang Zengwei , Dai Houde
Published: February 2023

Objective. The quantitative assessment of Parkinsonian tremor, e.g. (0, 1, 2, 3, 4) according to the Movement Disorder Society-Unified Parkinson’s Disease Rating Scale, is crucial for treating Parkinson’s disease. However, the tremor amplitude constantly fluctuates due to environmental and psychological effects on the patient. In clinical practice, clinicians assess the tremor severity for a short duration, whereas manual tremor labeling relies on the clinician’s physician experience. Therefore, automatic tremor quantification based on wearable inertial sensors and machine learning algorithms is affected by the manual labels of clinicians. In this study, an automatic modification method for the labels judged by clinicians is presented to improve Parkinsonian tremor quantitation. Approach. For the severe overlapping of dynamic feature range between different severities, an outlier modification algorithm (PCA-IQR) based on the combination of principal component analysis and interquartile range statistic rule is proposed to learn the blurred borders between different severity scores, thereby optimizing the labels. Afterward, according to the modified feature vectors, a support vector machine (SVM) with a radial basis function (RBF) kernel is proposed to classify the tremor severity. The classifier models of SVM with RBF kernel, k-nearest neighbors, and SVM with the linear kernel are compared. Main results. Experimental results show that the proposed method has high classification performance and excellent model generalization ability for tremor quantitation (accuracy: 97.93%, precision: 97.96%, sensitivity: 97.93%, F1-score: 97.94%). Significance. The proposed method may not only provide valuable assistance for clinicians to assess the tremor severity accurately, but also provides self-monitoring for patients at home and improve the assessment skills of clinicians.
Microstructure and electrical properties of green electrospun PVDF-HFP nanofibers
Authors: Khao-iam J , Salea A , Chaipo S , Putson C
Published: February 2023

Currently, with the recent increase of concern on the environmental hazards, toxicity, chemical and toxic waste, there has been growing interest in “green solvents” as alternative solvents instead of toxicity solvents. Most of the research reported on the preparation of Poly (vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) by using N, N- dimethylformamide (DMF) as a solvent which is considered a cancerogenic substance. Alternatively, dimethyl sulfoxide (DMSO) will be selectively decided as a low toxicity solvent and not hazardous. In this research, the mixture solvents of acetone/DMSO which was used as a co-solvent for the excellent fabricated PVDF-HFP nanofibers by using the electrospinning technique. The PVDF-HFP nanofiber membranes with various solvent ratios of 60:40, 70:30 and 80:20, denoted as A6D4, A7D3, and A8D2, respectively. All nanofiber films were investigated and characterized on the morphology, dielectric properties, and percentage of crystallinity. As a result, the dielectric constant of nanofiber membranes increased with the acetone contents. The maximum dielectric constant is devoted to A6D4 at 10 Hz. The copolymers structure with a different solvent ratio was modified β-phase which significantly affected the bandwidth dielectric properties. These fabricated PVDF-HFP nanofibers with the difference in the solution mixture can tune the electrical properties and phase orientation, and those fabricated nanofibers can be promoted in terms of energy storage, energy conversion, sensors, and electrocaloric application.
UV germicidal rays working with timer and motion sensors
Authors: Kobkam C , Dangudom K
Published: February 2023

As a result of coronavirus (COVID-19) epidemic, the public has become actively involved in bodily sanitation. The “New Normal” lifestyle now focuses on cleanliness and disinfection to prevent the spread of germs. This research designed and programmed a microcontroller for a UVC disinfection system using an Arduino board as an open-source electronic platform operated with a motion sensor (PIR) and timer control module (RTC). The optical properties of an 8 Watt (W) UVC source were measured. The four UVC sources investigated had wavelengths ranging from 251 to 577 nm. A UVC wavelength of 251 nm eradicates germs but also destroys tissues and is harmful to humans. Experimental result showed that UVC intensity decreased with distance from the source according to the exponential decay function. A control system, installed inside a building to kill germs when there are no humans or pets, can control UVC light source operation with a maximum power of 2kW. Operational time can be adjusted by setting on the control case, while as an additional level of safety, the system can be turned off if a motion sensor detects movement. Movement detection distance at an angle of -90 to 90 degrees was recorded. Result gave 11 m detection distance at an angle of 0 degrees, with more than 3 m detection distance at -45 to 45 degrees, as suitable for installation above a door. This timer and motion sensor-operated UV germicidal ray system can be safely deployed to keep rooms germs free.
Assessment of annual effective dose due to inhalation and ingestion of radon from groundwater at Kantharawichai District, Maha Sarakham Province
Authors: Atyotha V , Boonkhuang A , Sola P , Somtua J
Published: February 2023

Assessment of annual effective dose due to inhalation (Dinh) and ingestion (Ding) of radon from 43 groundwater samples at Kantharawichai District, Maha Sarakham Province using Radon Gas Monitor ATMOS 12 DPX. The results were as follows: 1. radon concentrations ranged from 1.04 – 21.87 Bq/L with a mean of 8.26±3.77 Bq/L, 2. The Dinh ranged from 2.60 – 54.69 μSv/y with a mean of 20.70±9.40 μSv/y. The Ding ranged from 0.19 – 3.94 μSv/y with a mean of 1.50±0.70 μSv/y, 3. The annual effective dose on organs, namely the dose on lungs (Dlung) ranged from 6.26 – 131.24 μSv/y with a mean of 49.60±22.70 μSv/y, and the dose for stomach (Dstomach) is 0.45 – 9.45 μSv/y with a mean of 3.60±1.60 μSv/y, and 4. The mean of excess lifetime cancer risk (ELCR×10-4) in males was 0.90±0.40 and in females, it was 0.96±0.44. The results will be compared with the action levels of various organizations, including. The maximum allowable radon concentration in water is 11.1 Bq/L, according to US EPA, and the allowable annual effective dose is 100 μSv/y, in accordance with WHO. Analysis of results can signify the health safety of radon inhalation and ingestion of groundwater from the study area.
Colorimetric sensor for formaldehyde detection using thiol-functionalized polydiacetylene and zinc oxide nanocomposites
Authors: Siribunbandal P , Pudwat S , Osotchan T , Jaisutti R
Published: February 2023

Formaldehyde is a toxic pollutant that harmful effect on human health. This work focus on the development of a colorimetric sensor to detect formaldehyde solution using composites of polydiacetylene (PDA), thiol-functionalized polydiacetylene (PDA-SH) and zinc oxide (ZnO) nanosheets. The as-prepared PDA/PDA-SH/ZnO vesicles exhibit a blue color, and change to a red color in the presence of formaldehyde solution. With increasing formaldehyde concentrations, the optical absorption spectra show the decreasing of absorption intensity at 640 nm wavelength, and new absorption peak occurred at 540 nm wavelength with increasing its intensity. Additionally, the PDA/PDA-SH/ZnO sensor exhibit high selective to formaldehyde and its color transition is easily observed by the naked-eye. These results indicate a possibility to use PDA/PDA-SH/ZnO sensor for on-site monitoring formaldehyde in an environment.
The effects of hair-cell polarity on the dynamics of two coupled hair-cell bundles of the inner ear
Authors: Ngampattrapan T , Roongthumskul Y
Published: February 2023

Hair cells are the sensory receptors of the auditory and vestibular systems. A bundle of cilia situated atop each hair cell, termed the hair-cell bundle, is deflected upon an impinging of a mechanical force. This modulates the open probability of mechanically gated ion channels and subsequently alters the hair cell’s membrane potential. Owing to the asymmetry in the hair bundle’s geometry, individual hair cells are polarized and display the maximal response to a force applied toward a direction that opens the ion channels. The auditory organs of most vertebrates comprise primarily of hair cells with identical polarity, whereas hair cells of the vestibular organs are organized in two opposing polarities. To understand the advantages of the bi-polarity arrangement of vestibular hair cells, we employed the theoretical framework that describes each hair-cell bundle as an active nonlinear oscillator displaying a Hopf bifurcation. Our results from numerical simulations revealed that coupling of two hair-cell bundles with opposite polarities significantly altered the value of the critical control parameter at a Hopf bifurcation. When driven by a step force, coupled hair-cell bundles with identical polarities displayed a maximal displacement in the direction which closed the ion channels. On the other hand, reversing the polarity of a hair-cell bundle rendered the system sensitive to bi-directional step forces. Lastly, we showed that coupling hair-cell bundles with opposite polarities did not significantly alter the response to sinusoidal forces.
Flow dependence of handheld breath analyzer for body fuel utilization monitoring
Authors: Sricharoen C , Waritananta T , Wattanavicheana N , Jaisuthi R , Osotchan T
Published: February 2023

Home healthcare medical technologies have been gaining popularity and are more affordable in recent years. Exhaled breath analysis has potential in this field. The development of gas sensor technology has enabled us to build a small affable breath analysis device with the electronic nose concept. In this work, a handheld breath analyzer was developed for monitoring body fuel utilization. A hybrid gas sensor array, including electrochemical and photoacoustic gas sensors, was used to accurately measure oxygen and carbon dioxide in exhaled breath. The bypass configuration volume flow measurement method was developed to fit a small portable device. The experiment shows that both oxygen and carbon dioxide sensors are flow-dependent due to the slow response time of each sensor type. The response of the photoacoustic sensor is relatively slower than those of other sensor types. Thus, a mathematical model was developed to correct the individual sensor value to get a more accurate value of body fuel utilization. The comparison protocol of known concentrations of the oxygen and carbon gases with various flow conditions was conducted, and the mathematical model for reconstructing the original gas concentration was proposed. The result shows that the device is able to detect the RER change of humans after having a high carbohydrate content meal and after exercise
The effects of mechanically gated ion channels of the inner ear on thermal sensitivity of spontaneous otoacoustic emissions
Authors: Sawangwareesakul K , Ngampatrapan T , Roongthumskul Y
Published: February 2023

In quiet environments, the inner ears of vertebrates can produce low intensity sounds that are detectable in the ear canal, termed spontaneous otoacoustic emissions (SOAEs). This background activity of the inner ear has been regarded as an epiphenomenon of the active processes performed by hair cells – the sensory receptors of the auditory system. Experimental measurements of SOAEs from the ears of tokay geckos reveal a linear increase of SOAE frequency with body temperature, with the emission at higher frequencies displaying greater thermal sensitivity. In this work, we elucidated the cellular mechanism underlying the thermal sensitivity of SOAE frequency using a mathematical model of hair cell’s transduction process performed by mechanically gated ion channels. We employed the previously proposed gating-spring model which described an individual ion channel by a two-state system, whose activation energy associated with channel gating depended on the level of temperature. Our results from numerical simulations revealed that a rise in temperature elicited an increase in the frequency of spontaneous oscillations displayed by a single hair cell. The magnitude of the frequency shift increased with the oscillation frequency following a quadratic polynomial, a characteristic observed in the physiological recordings of SOAEs from tokay geckos. The model further suggested that the intrinsic energy difference between the open and closed state of the ion channels greatly controlled the temperature sensitivity of a hair bundle.
Coordinates transformation method for pointer gauge reading by machine vision
Authors: Jinuntuya P , Sudatham W , Jinuntuya N
Published: February 2023

In this report we present a machine vision algorithm for pointer gauge reading based on coordinates transformation. Since a pointer gauge is a polar representation of a linear scale, it is possible to transform its polar reading to the original linear counterpart. Once the picture of a pointer gauge is captured digitally, we can assign the polar positions to each pixel of the image. Those polar coordinates can be plotted on a rectangular frame to form a transformed image. The scale lines and the pointer are transformed to point vertically (or horizontally). Locations of the scale lines and pointer can be obtained from their pixel histograms maxima. The main advantage of our algorithm is its simplicity. We can read the pointer orientation and scale lines position of a pointer gauge directly from its geometrical structure. The complication of feature extraction process from the conventional algorithm, e.g., Hough transformation, can be avoided. We have tested the algorithm with the ideal and real image of pointer gauges. In the latter case, even though there are some noises on the transformed image, the locations of pointer and scale lines can still be easily found. Due to its simplicity, our algorithm is fast. We expect that our method can be useful in practice as an alternative machine vision algorithm when the real time pointer gauge reading system, e.g., the automatic dial gauge tester, is needed.
An estimation of net radiation from global solar radiation in the main regions of Thailand
Authors: Tohsing K , Phoemwong C , Uearsri C , Saiplang P
Published: February 2023

Net radiation can be used for different purposes, especially for studying the energy or radiation balance, which can be further analysed to investigate a global warming. In order to utilize these applications, it is necessary to know the amount of net radiation in that area. This can be done by installing a net radiometer for measuring the net radiation. However, there are few monitoring stations of net radiation compared to a global solar radiation in Thailand. Therefore, this research aims to analyse a statistical characteristic of the measured net radiation and to develop a model for estimating the net radiation from the global solar radiation at four solar monitoring stations in the main regions of Thailand, namely Chiang Mai, Ubon Ratchathani, Songkhla and Nakhon Pathom during the year of 2017 to 2021. The results showed that the most net radiation of these stations had a range of 8 to 14 MJ/m2. The relationship between daily and monthly average daily net radiation and global solar radiation was found to be a linear. After that, the developed model was validated by comparing the estimated and measured net radiation. The discrepancy between the calculated net radiation and that obtained from the measurements was presented in terms of root mean square difference (RMSD) and mean bias difference (MBD) ranged from 6.98% to 16.03% and -1.82% to 7.09%, respectively.
An application of autocollimator for strip surface profile measurement
Authors: Kaewpho S , Kerdkaew C , Samnasen K , Chomkokard S , Yaemglin T , Cheowanish I , Wongkokua W , Jinuntuya N
Published: February 2023

The autocollimator is a non-contact angle measuring instrument using the geometric light reflection principle. The instrument can be used in scientific research and industrial applications with high resolution. In this work, we propose an application of the autocollimator for surface profile measurement. We use an autocollimator to directly measure the tangent profile of a surface. The results can be interpreted as the first partial derivative of the surface along 2 reference axes. The higher derivatives can then be calculated. For second-order bi-quadratic approximation, the second derivatives are used to estimate the bending and twisting of a local surface for a strip material. We compare our results with that of the industrial, high-resolution interferogram. The results agree well with the RMSE ranging from 2 nm to 18 nm.
Application of ultrasonic sensor and Arduino in analysing motion of damped pendulum
Authors: Methet S , Chattrapiban N , Wattanakasiwich P
Published: February 2023

An easy-to-setup experiment designed to measure the period and air drag coefficients of a damped pendulum is reported. The setup is made up of a solid metal ball and cylindrical shells of various sizes to create air drag. An ultrasonic position sensor (HC-SR04) and an Arduino Uno board were located beneath the pendulum’s lowest position. The pendulum was released from a fixed height at a small initial angle. The periods of the oscillations involving different cylindrical shells were obtained from the time series plots of the pendulum’s position when the pendulum moves back and forth above the sensor. The drag coefficients were measured from five different values of string length. The coefficient was proportional to the size of the cylindrical shells and in agreement with the drag equation for a small Reynolds number.
Backscattering and transmission Raman spectroscopy systems in the quantitative analysis concentration of acetone solutions
Authors: Charoenrit T P , Wicharn S , Puttharugsa C , Limnonthakul P , Sassuvun W , Buranasiri P , Plaipichit S
Published: February 2023

Raman spectroscopy is a set of techniques based on Raman scattering properties, widely applied to analyze the composition of various substances. The techniques consist of 1) backscattering, which collects Raman signals scattered from the surface of a sample; and 2) transmission, which collects Raman signals transmitted by the surface of a sample in the opposite direction of a light source (which triggers less fluorescence than backscattering). In this paper, we will measure the Raman spectrum of acetone solution by the transmission Raman spectroscopy and the backscattering Raman spectroscopy systems that we set up. Those accessories we use are a 532-nanometer diode laser with 100 milliwatt power as the light source, a focusing lens, an objective lens used for amplifying the Raman signals scattered from the sample, and a long-pass filter used to block light with a wavelength shorter than 532 nanometers. For the experimental samples, there are acetone solutions each prepared at 1M, 3M, 5M, 7M, 9M, 11M, and 13M. In the results of this experiment, we found that the intensity of Raman peaks for each Raman shift of acetone and the molar concentrations of acetone measured by both systems have a linear function in the backscattering Raman system and have a quadratic function in the transmissions Raman system because in backscattering system have noise by fluorescence effect more than in transmission system and it might be the effect of the Beer-Lambert law.
Demonstration kits for locating an image formed by a concave mirror
Authors: Srijareon P , Emarat N , Arayathanitkul K
Published: February 2023

To improve student understanding about an image formed by a concave mirror, 2 demonstration kits were developed. One kit is used to view and locate images formed and find the image distances and sizes. The other uses a laser beam to show the incident and reflected light rays and relate to the ray diagram normally used to find the image location. The demonstration kits were applied to year-11 Thai high-school students for both online (N = 32) and on-site (N = 22) classes. The 4 diagnostic questions were used to investigate student understanding, covering the image visualization, the mirror equation, and the ray diagrams of a concave mirror. The mean scores of the pre- and post-test are 1.3 and 5.3 out of 13, respectively, and the averaged normalized gain is 0.34. Interestingly, the normalized gains of the two classes are not significantly different indicating that the demonstration kits can be applied to either an online or on-site class. The best improvement was found in the image visualization question. In addition, the demonstration kits make the physics content enjoyable. The students found it exciting and fun while much is being learned.
Experiment and simulation of heat treatment for disinfection in the chicken farm using IR irradiation
Authors: Kaewthong Jutarat , Satienpaisan Wuttipan , Krabuansang Kullapat , Artsri Jurarat , Chaisakul Papichaya , Chiangga Surasak , Chattham Nattaporn , Samipak Sompid
Published: February 2023

Chicken meat is widely consumed worldwide and in order to supply the growing demand, chickens are raised in large factory farms. To prevent contaminated chicken meat being released into the market, a good hygiene practice must be strictly followed. Materials utilized in chicken farming must be completely sanitized including the rice husks that are normally being used as a floor covering material. Aiming to improve rice husk disinfection protocol, infrared radiation (IR) was utilized as an effective, time-saving, and environmental friendly method. A proof-of-concept prototype of rice husk disinfection apparatus equipped with IR source and a rotating conveyor belt was developed. Finite element analysis using COMSOL Multiphysics to simulate heat transfer of IR irradiation to rice husk was performed. The effectiveness of IR irradiation method was analysed using the rice husks that were spiked with Salmonella typhimurium. The total aerobic bacteria plate count showed that the most effective IR rice husk treatment was at 120 ºC for 3 min of exposure time.
Surface treatment of PTAA hole transport layer for inverted perovskite solar cells
Authors: Butsriruk K , Passokorn P , Taychatanapat T , Chatraphorn S
Published: February 2023

Poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) was chosen as a hole transport layer for inverted perovskite solar cells (PSCs). It is the first layer deposited on the FTO substrate and thus directly affect the structure and performance of the PSCs. It was found that untreated PTAA surfaces yielded large distribution of photovoltaic parameters and low reproducibility. In this work, the PTAA powder was dissolved in chlorobenzene (CB) and spin-coated on the FTO substrates and baked at 105 °C for 10 mins as pristine samples. The surface treatment of PTAA was performed by washing the pristine samples with 200 µl dimethyl formamide (DMF) on a spin coater and followed by dynamic spin of 50-75 µl of CB or Toluene (TO). It was observed that the surface treatment affected the wettability of PTAA surface by the reduction of contact angle from 46° of pristine sample to 25° – 35° of treated samples that could lead to a better interface and formation of a MAPbI3 perovskite layer. On the contrary, the optical transmittance and surface morphology the treated samples were insignificantly affected. It was demonstrated that the surface treatment of PTAA using DMF and 50 µl of TO could significantly reduce the fluctuation of photovoltaic parameters and also improve the repeatability of the fabrication process. The maximum power conversion efficiency (PCE) of 15.4% was obtained for the optimal condition.
Characteristics of MSNs synthesized by structure directing method
Authors: Hutem A , Yuenyao C
Published: February 2023

The high specific surface area (SSA) mesoporous silica nanoparticles (MSNs) are synthesized and characterized in this work. The structure directing method combined with the co-condensation and bi-phasic processes are employed to fabricate the porous particles. Myristyltrimethylammonium bromide (MTAB) is utilized as the major structure directing agent. Triton X-100 and triethanolamine (TEA) are employed as the co-structure directing agents. In order to generate a bi-phasic environment and increase the reaction rate, cyclohexane (CHX) and L-Arginine (LAG) are used, respectively. To swelling of the structure directing agents, the solution of structure directing agents, solvent and catalyst is subjected to sonicate by ultrasonic wave with the frequency of 40 kHz. In the research, as synthesized sample of particles are characterized by different scientific techniques. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are utilized to analyze the morphology and pore formed on the obtained particles. The N2 adsorption-desorption isotherm testing integrated with the BET and BJH calculation techniques are employed to determine the SSA, mean pore diameter and total pore volume of the resultant particles at relative pressure of 0.99. Results from the tests as mentioned revealed that SSA of particles synthesized by using only MTAB as a structure directing agent, is about 672.30 m2/g while SSA of particles fabricated by using MTAB+TEA and MTAB+triton X-100 is 691.45 and 651.93 m2/g, respectively. A mean pore diameter and total pore volume of the obtained particles are 4.9, 7.5, 3.9 nm and 0.83, 1.30, 0.63 cm3/g when MTAB, MTAB+TEA and MTAB+X-100 are used as structure directing agents, respectively. Porous particles with uniform size distribution are successfully synthesized and confirmed by SEM and TEM micrographs, respectively. Finally, TEM-EDX confirmed that the synthesized particles are silica (SiO2) nanoparticles.
Influence of Cu-atomic ratio in the 3-stage deposition technique on the efficiency of CuIn1-xGaxSe2 solar cells
Authors: Namnuan B , Chatraphorn S
Published: February 2023

The 3-stage co-evaporation technique is one of the deposition processes used to fabricate photon absorber layer in high efficiency CuIn1-xGaxSe2 (CIGS) solar cells. For this technique, the [Cu]/[III] ratio (y), where [III] refers to group-III elements, evolves from Cu-poor (y < 1) to Cu-rich (y > 1) in the 2nd stage and finally ends with slightly Cu-poor (y ~ 0.9) in the 3rd stage of the 3-stage process. Here, the highest values of [Cu]/[III] in the 2nd stage are intentionally varied from 1.0 to 1.5 by setting the deposition time of the pre-calibrated Cu and Se fluxes in the 2nd stage. The [Ga]/[III] ratio (x) is set at 0.37 during the 1st and 3rd stages in all devices. The influences of the Cu-atomic ratio are examined for the crystal grain growth, elemental depth profiles of the CIGS absorbers as well as the photovoltaic parameters and external quantum efficiency (EQE) of the CIGS solar cells. The optimal value of y = 1.3 is found to provide the highest efficiency CIGS device. The double-grading depth profile in the [Ga]/[III] ratio has also been observed despite the constant fluxes of group-III elements set during the whole process. The performances of the CIGS solar cells are investigated under AM1.5 condition and found to have open-circuit voltage (V
OC) of 670 mV, short-circuit current density (J
SC) of 33.2 mA/cm2, fill factor (FF) of 75.5% and the power conversion efficiency of 16.8% for the best CIGS device. The J
SC of the device with y = 1.3 is relatively higher than other devices due to the increase of photo-generated currents in the short wavelength region as seen in the EQE spectrum.
First principles study on thermal conductivity of nitrogen substituted diamane
Authors: Khamkaeo Sakarn , Pakornchote Teerachote , Ektarawong Annop , Bovornratanaruks Thiti , Hongo Kenta
Published: February 2023

2D materials have been in the spotlight due to their impressive properties since graphene was successfully synthesized. A single-layered diamond or diamane, which has high thermal conductivity and high stiffness inherited from its bulk counterpart, is a candidate for heat dissipating applications in nanodevices. Unfortunately, non-passivated dangling bonds on the surface of pristine diamane can cause its structural instability. Recent theoretical studies have suggested that site-specific substitution of N for C could stabilize the diamane’s structure without surface termination. Beside its superhard properties inherited from bulk carbon nitrides, thermal properties of N-substituted diamane have not been revealed. In this work, we investigate thermal properties of N-substituted diamane through first principles study. Our results show that there is an emergence of flexural phonon branch, which is regularly seen in 2D materials, and it contributes large thermal conductivity to N-substituted diamane. The thermal conductivity of N-substituted diamane is decreasing as the temperature increasing. At room temperature, it is 33% lower than that of diamond and 15-35% higher than that of hydrogen passivated diamane (H-diamane).
Effect of annealing temperature on thermoelectric properties of YBa2Cu3O7-xceramic
Authors: Wannasut P , Yawirach S , Boonsong P , Watcharapasorn A
Published: February 2023

We have studied the effect of annealing temperature on oxygen content and thermoelectric properties of YBa2Cu3O7-x(YBCO) ceramics fabricated by hot-pressing method. The as-calcined powder was subjected to the applied pressure of 70 MPa at 800 °C for 1 h under Ar atmosphere. The YBCO ceramics were then annealed at 700 and 750 °C for 4 h in oxygen atmosphere. The XRD results showed that all samples possessed pure orthorhombic YBCO phase. The annealing process seemed to induce the reduction of the electrical conductivity and metallic-to-semiconducting transition when the annealing temperature was increased. The temperature dependence ofZTshowed a close relation to that of electrical conductivity, suggesting the dominant role of the charged carriers present in these samples.
Influence of glycine addition on formation and magnetic properties of MnBi prepared by vacuum sintering technique
Authors: Eknapakul T , Ngamsomrit S , Pinitsoontorn S , Songsiriritthigul P
Published: February 2023

An alternative way to increase a low-temperature phase MnBi (LTP-MnBi) content synthesized by low-temperature vacuum sintering is by using Mn powder with small particle sizes. To reduce the particle size by ball milling, glycine was added to prevent particle agglomeration and possible oxide formation. The ball-milled Mn and Bi powders were fixed at an atomic ratio of 1:1. The ball-milling time in glycine was between 1 and 3 hrs. The average particle size reduces from 400 µm (original) to 35-40 µm and 15-20 µm after grinding for 1 and 3 hr, respectively. Sintering of the mixtures was carried out at 275 °C for 12 hours at a vacuum pressure of less than 5×10−8 mbar. The LTP-MnBi samples sintered from 1 hr (MnG1Bi) and 3 hr (MnG3Bi) glycine-added Mn grinding times were investigated by XRD, SEM, XPS, and VSM. The coercivity values (H
c) are 3.95 ± 0.04 and 2.35 ± 0.03 kOe for MnG1Bi and MnG3Bi, respectively. The saturation magnetization (M
s) of MnG1Bi and MnG3Bi is relatively low (~0.18 emu/g) compared to the samples prepared by conventional ball-milling, i.e., without adding glycine in grinding. The XRD results show a few percentages of MnBi content in all samples, suggesting that glycine addition could prevent MnBi formation. The coverage of hydrocarbon (i.e., NH2-CH2-COOH) groups on Mn particles could prevent the diffusion mechanism during liquid-phase sintering. Moreover, it was found that the oxygen and carbon content in the MnGxBi were much higher than the conventional ball-milled MnBi.
Improvement in reproducibility of large-scale perovskite solar cells using automatic liquid injection in antisolvent method
Authors: Insri Watcharakiart , Kanlayapattamapong Thanawat , Homnan Saowalak , Wongratanaphisan Duangmanee , Gardchareon Atcharawon , Ruankham Pipat
Published: February 2023

Perovskite solar cells are the most promising technology for highly efficient and cost-effective light-to-electricity conversion devices. To achieve high-quality and reproducible perovskite photo-absorbers in these devices, a great variety of deposition methods has been introduced. The widely used antisolvent approach is an efficient way for producing a homogeneous and dense perovskite films. However, the reproducibility of the obtained perovskite films is low due to uncontrollable parameters during the antisolvent dripping. In this work, an automatic liquid injection machine was used for controlling the antisolvent dripping parameters and enhancing the reproducibility of large-scale (>1 cm2) perovskite solar cells. Additionally, when compared to a manual liquid dropping, the automatic liquid injection improved the precision and consistency of liquid droplets. Our proposed method could reduce manual production tolerances and improve the reproducibility and accuracy for fabricating large-scale perovskite solar cells. Finally, it enhances manufacturing capacity and reduces the amount of waste produced during production.
Effect of Ni-Co transition metal ratios on structure-function of Lithium Aluminium Borate Glasses for battery electrode
Authors: lomon J , Padchasri J , Siriroj S , Montreeuppathum A , Chanlek N , Songsiriritthigul P , Kidkhunthod P
Published: February 2023

The Lithium Aluminum Borate Glasses (Li2O-Al2O3-B2O3) doped with various concentrations of xNi: Co (where x = 1, 2, 3, and 4) effectively synthesized by melt-quench process. Glasses made of nickel-lithium borate have undergone rigorous study to determine the impact of nickel-cobalt content on the operation of electrochemical characteristics and battery performance. The phase structure of all samples was confirmed using TEM diffraction XRD patterns. Intriguingly, at a scan rate of 5 mV/s, the 1Ni: Co glass electrode displayed the highest specific capacitance of 76.6 F/g. By adjusting the Ni:Co ratio in the glass structure, produced (Li2O-Al2O3-B2O3) glasses exhibit improved electrochemical characteristics.
Coalescence of nematic liquid crystal droplets on freely suspended liquid crystal films
Authors: Kaewthong Jutarat , Satienpaisan Wuttipan , Hongkarnjanakul Natthawat , Tin Padetha , Chattham Nattaporn
Published: February 2023

Freely suspended smectic films of a few molecular layers thick is a model system that can be used to study two dimensional phenomena. In our study, we drew a smectic C film across a few millimeter hole and stabilized it with a strong surface tension capable of suspending 5CB nematic liquid crystal droplets sprayed onto it. Thermal fluctuation of liquid crystal molecules is observed across the smectic C film and can cause the droplets to be driven closer and coalesce. The coalescence in this environment has yet to be studied more extensively. When two droplets are touching each other, connecting bridge between them forms and rapidly grows while they merge. Coalescence between them was thoroughly studied through high-speed camera under the cross-polarized observation and different regimes during coalescence process were analysed. Scaling law for various regimes will be discussed and explained. To understand the experimental result further, we also perform the study of droplet coalescence through finite element software which include inertial force, interfacial force and viscous force in the model. Comparing and analyzing the experimental and simulation results.
Sensitivity of Gaussian energy broadening function of MCNP pulse height spectra on CLYC7 scintillation detector
Authors: Buakham S , Sangaroon S , Ogawa K , Isobe M
Published: February 2023

The Cs2LiYCl6:Ce crystal (CLYC) is an inorganic scintillator which has been developed for the γ-ray and neutron measurement with the high detection efficiency, high resolution, and no need unfolding technique. To enhance the measurement of the fast neutron, the CLYC with 7Li-enrichment (CLYC7) scintillator is developed. In this work, the response of the CLYC7 detector to γ-ray is obtained using 137Cs γ-ray calibration source and calculated using Monte Carlo N-Particle transport code (MCNP). A comparison of measured and calculated γ-rays spectra is complicated by the fact that physical radiation detectors have finite energy resolution. In this study, we treated detector energy resolution effect by Gaussian energy broadening (GEB) in MCNP pulse height spectra calculation. We observe the parameters in the GEB function which provides simulation spectrum matches the experiment spectrum, especially on the photopeak region. The detail sensitivity of GEB function on CLYC7 scintillation detector is presented in this work.
Development of a 6 MeV electron beam energy Linac for fruit sterilization
Authors: Chunjarean S , Manasatitpong K , Yachum N , Phacheerak W , Kokkrathoke S , Pongampai S , Kulthanasomboon P , Jummunt S , Klinkhieo S
Published: February 2023

Treatment of fresh fruits, meat, and food with ionizing radiation has been frequently chosen to destroy harmful pathogenic microorganisms and oriental fruit flies. Electron beam linear accelerator (Linac) is commonly used as the source of irradiation to produce photons and electrons in megavolt energy. A 6 MeV Linac designed for medical therapy has been developed for fresh fruit sterilization at Synchrotron Light Research Institute (SLRI). Some physical design and beam dynamic results of the electron gun and 6 MeV Linac will be presented in this paper. Testing of each subsystem and installation of the 6 MeV Linac with major auxiliary systems will be described in this paper. It is the first system designed, fabricates, and tested in-house for the fruit sterilization application at SLRI. Measurement results of the Linac properties are presented as a resonant frequency and coupling coefficient at low power called a cold test. The Linac system with all sub-systems and the auxiliary systems will be installed and tested before x-rays production. During commissioning some electron beam parameters out of the electron gun and the Linac exit will be measured.
Design, construction, and measurement of electromagnetic steering magnet for 25-MeV electron accelerator system
Authors: Kitisri P , Khangrang N , Kitisri T , Rimjaem S
Published: February 2023

Mid-infrared and terahertz free-electron laser (MIR/THz FEL) facility is under the construction at the PBP-CMU Electron Linac Laboratory (PCELL) in Chiang Mai University. For producing MIR-FEL, electron beams with an energy of 25 MeV accelerated by a radio-frequency linear accelerator (RF linac) are required. Transporting the 25-MeV electron beam from the linac to the MIR-FEL station requires small dipole magnets for steering the electron beams along the beamline. This work focuses on the design, construction, and measurement of an electromagnetic steering magnet for controlling the electron beam trajectory. A computer software, CST Studio Suite 2022 is used for the 3D magnetic field simulation of the magnet. The physical length of the magnet and the diameter of copper coil are decided based on the simulation and calculation results. After the construction, a hall probe with a measuring system controlled by a computer program is used to measure the magnetic field for comparison with the simulation results. From simulated and calculated results, the steering magnet with a length of 40 mm and the coil with a diameter of 1.06 mm was chosen. At an applied current of 1.8 A, this steering magnet can bend the 25-MeV electron beam with a bending angle of 13.7 mrad. The measured magnetic field is consistent with the simulated results. The advantage of this steering magnet is that it can be assembled on a square frame for steering the beam in both horizontal and vertical direction. It can also be used for the THz-FEL beamline, which requires the electron beam with an energy of 10-16 MeV.
Construction and tests of phosphor view screen station for monitoring transverse profile of electron beam at PCELL
Authors: Khangrang N , Kitisri P , Saisut J , Techakaew K , Rimjaem S
Published: February 2023

Development of an accelerator-based light source for generating coherent terahertz (THz) and mid-infrared (MIR) free-electron laser (FEL) is ongoing at the PBP-CMU Electron Linac Laboratory (PCELL). For producing high quality radiation, suitable electron beam property is necessary. In particle accelerator technology, transverse beam distribution and profile can be measured by using several techniques. The beam monitoring using view screen station is one of popular and effective methods. At PCELL, we use stations consisting of phosphor screen equipped with CCD camera to monitor, measure and record the beam image along the accelerator system and beamlines. The phosphor screen was chosen due to its high spatial resolution. The phosphor film is uniformly coated on a thin aluminium plate. Its green emission when electrons hitting the screen is matched well with the respond of the CCD camera. The screen can be moved in and out from the vacuum chamber using the air pressurized linear actuator. This paper presents about design, construction and tests of the screen stations at PCELL. The resolution of measurements for beam transverse profile and emittance is also be discussed.
Preliminary study of supersonic molecular beam injection in Thailand Tokamak-1 using 3D fluid model
Authors: Rongpuit Kitti , Wisitsorasak Apiwat , Promping Jiraporn
Published: February 2023

Successful operation of a tokamak relies on effective and appropriate methods of plasma fueling. The development plan of Thailand Tokamak-1 (TT-1) will employ the supersonic molecular beam injection (SMBI) which delivers the fueling gas more effectively and deeper than the gas puffing method. In this work, we study the effect of SMBI on the plasma transport of TT-1 plasma by using 3D fluid simulation. The model includes the continuity equation, energy balance equation, momentum equation, continuity of fuel equation, and momentum of fuel. BOUT++ is then used to solve these equations by a finite difference method with the field-aligned coordinates in the edge region. The simulation shows that when hydrogen fuel gas is by the SMBI method from the low-field side into the plasma with a speed of 1000 m/s, the electron density in the edge locally rises as a result of the dissociation and ionization. The ion and electron temperatures then drop. After that, the density spread over the whole plasma volume within about 10 ms. When the injection speed increases, it results in a deeper penetration length of the fuel deposition.