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Thailand's hospitals face overcrowding, particularly with non-communicable disease (NCD) patients, due to a doctor shortage and an aging population. Most literature showed implementation merely on web or mobile application to teleconsult with physicians. Instead, in this work, we developed and implemented a telemedicine health kiosk system embedded with non-invasive biosensors and time-series predictors to improve NCD indicators over an eight-month period. Two cohorts were randomly selected: a control group with usual care and a telemedicine-using group. The telemedicine-using group showed significant improvements in average fasting blood glucose (148 to 130 mg/dL) and systolic blood pressure (152 to 138 mmHg). Data mining with the Apriori algorithm revealed correlations between diseases, occupations, and environmental factors, informing public health policies. Communication between kiosks and servers used LoRa, 5G, and IEEE802.11, which are selected based on the distance and signal availability. The results support telemedicine kiosks as effective for NCD management, significantly improving key NCD indicators, average blood glucose, and blood pressure. [ABSTRACT FROM AUTHOR]

Installing a battery energy storage system (BESS) and renewable energy sources can significantly improve distribution network performance in several aspects, especially in electric vehicle (EV)-integrated systems because of high load demands. With the high costs of the BESS and PV, optimal placement and capacity of them must be carefully considered. This work proposes a solution for determining the optimal placement and capacity of a BESS and photovoltaic (PV) in a distribution system by considering EV penetrations. The objective function is to reduce system costs, comprising installation, replacement, and operation and maintenance costs of the BESS and PV. The replacement cost is considered over 20 years, and the maintenance and operation costs incurred in the distribution system include transmission line loss, voltage regulation, and peak demand costs. To solve the problem, two metaheuristic algorithms consisting of particle swarm optimization (PSO) and the African vulture optimization algorithm (AVOA) are utilized. The tenth feeder of Phitsanulok substation 1 (PLA10), Thailand, which is a 91-bus distribution network, is tested to evaluate the performance of the proposed approach. The results obtained from the considered algorithms are compared based on distribution system performance enhancement, payback period, and statistical analysis. It is found from the simulation results that the installation of the BESS and PV could significantly minimize system cost, improve the voltage profile, reduce transmission line loss, and decrease peak demand. The voltage deviation could be reduced by 86%, line loss was reduced by 0.78 MW, and peak demand could be decreased by 5.706 MW compared to the case without BESS and PV installations. [ABSTRACT FROM AUTHOR]

Sentiment analysis is becoming a very popular research technique. It can effectively identify hidden emotional trends in social networks to understand people's opinions and feelings. This research therefore focuses on analyzing the sentiments of the public on the social media platform, YouTube, about the Thailand-China high-speed train project and the Laos-China Railway, a mega-project that is important to the country and a huge investment to develop transportation infrastructure. It affects both the economic and social dimensions of Thai people and is also an important route to connect the rail systems of ASEAN countries as part of the Belt and Road Initiative. We gathered public Thai reviews from YouTube using the Data Application Program Interface. This dataset was used to train six sentiment classifiers using machine learning and deep learning algorithms. The performance of all six models by means of precision, recall, F1-score and accuracy are compared to find the most suitable model architecture for sentiment classification. The results show that the transformer model with the WangchanBERTa language model yields best accuracy, 94.57%. We found that the use of a Thai language-specific model that was trained from a large variety of data sources plays a major role in the model performance and significantly increases the accuracy of sentiment prediction. The promising performance of this sentiment classification model also suggests that it can be used as a tool for government agencies to plan, make strategic decisions, and improve communication with the public for better understanding of their projects. Furthermore, the model can be integrated with any online platform to monitor people's sentiments on other public matters. Regular monitoring of public opinions could help the policy makers in designing public policies to address the citizens' problems and concerns as well as planning development strategies for the country. [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerators (TENGs) are crucial for applications such as smart sensors and bio-electronics. In the current work, we aimed for improved performance of TENGs with incorporation of BaTiO3 powder, which is known for its strong ferroelectric properties, combining it with epoxy resin to improve the flexibility of our devices. We observed that our TENGs can operate for over 24 000 cycles with no degradation of function. Additionally, we improved the electrical performance of the TENGs by incorporating various aluminum concentrations that change the electronic properties in the form of mixed epoxy resin, BaTiO3, and Al nanopowders. To identify the optimum conditions for the best performance, we analyzed the electrical characteristics and material properties by employing scanning electron microscopy, energy dispersive x-ray spectroscopy, and x-ray diffractometry characterization techniques. Our findings suggest that this innovative combination of materials and optimization techniques can significantly improve the performance of TENGs, making them ideal for practical applications in various fields, such as low-power electronics, environmental monitoring and healthcare. Moreover, these enhanced TENGs can serve as sustainable and dependable energy sources for various applications. [ABSTRACT FROM AUTHOR]

Flux-switching permanent magnet (FSPM) machines have attracted significant research attention in the field of wind power generation. In this study, the utilization of a magnetic flux barrier to improve the performance of the nine-phase FSPM generator designed for low-speed wind power applications is conducted. The proposed approach involves introducing magnetic flux barriers of different topologies to the conventional FSPM generator and analyzing their performance using 2D finite element simulations. Results suggested that |-shaped magnetic flux barriers exhibited the highest performance among other topologies, making them the appropriate choice for this generator. The geometry of the |-shaped flux barriers was further optimized using response surface methodology to maximize the generator's performance. The proposed generator exhibits a significant decrease in cogging torque, achieving a remarkable reduction of up to 23.7%, while maintaining electromotive force. Moreover, it shows a significant decrease in permanent magnet eddy-current loss, with a noteworthy reduction of up to 51%. Additionally, significant improvements were demonstrated in terms of electromagnetic torque, torque ripple, output power, and efficiency. Details on the physical reasoning behind these improvements have been provided. Overall, the proposed FSPM generator with inserted flux barriers has the potential to meet the demands of low-speed wind power generation effectively. [ABSTRACT FROM AUTHOR]

Machine ratio adaptation of a dual-PM modular doubly salient permanent magnet machine (DPM-DSPM) was proposed to improve the torque characteristics. An optimization design process was examined. Essential machine indicators were investigated to obtain an optimal machine ratio. It was found that p = 4 and a 0.8 rotor pole width ratio of the DPM-DSPM produced the best essential machine indicator that provided the appropriate magnetic flux path and high flux regulation quality. Then, the DPM-DSPM with an optimal machine ratio was investigated based on open-circuit and on-load tests and then compared to a reviewed DPM-DSPM. The results, based on 2-D finite element analysis, verified that the optimal proposed DPM-DSPM had better torque characteristics. In particular, the optimal proposed structure produced 35.04% higher electromagnetic torque with 61.75% lower ripple torque than the review structure. Therefore, an optimal machine ratio for a DPM-DSPM can be beneficial in solving industrial machine problems, especially noise reduction from vibration. [ABSTRACT FROM AUTHOR]

Human activities have been limited by coronavirus disease 2019 (COVID-19), and the normal conditions of our lifestyles have changed, particularly in terms of electricity usage. The aim of this study was to investigate the impact of COVID-19 on the power sector in the Lao PDR in 2020, as well as the challenge of using solar energy to supply power to the network using an optimal approach. The returns on investment of network extension and the purchase of solar energy were also evaluated. Furthermore, load conditions caused by the country's lockdown policy were analyzed. We analyzed the optimal sizing and location of solar energy using a particle swarm optimization method based on the main objective functions, with the system's power loss decreasing and its reliability improved. The results demonstrated that the suddenly reduced load from industry and commercial business did not have a large impact on its operations; however, revenue was reduced. The optimal method for connecting solar energy to a network can reduce power loss and improve system reliability. In addition, we discovered that the location and capacity of solar generation can reduce the investment costs of extensions for new lines, with the surplus power being exported. [ABSTRACT FROM AUTHOR]

In this work, we report a low-cost and highly sensitive electrochemical sensor for detecting As(III) in water. The sensor uses a 3D microporous graphene electrode with nanoflowers, which enriches the reactive surface area and thus enhances its sensitivity. The detection range achieved was 1–50 ppb, meeting the US-EPA cutoff criteria of 10 ppb. The sensor works by trapping As(III) ions using the interlayer dipole between Ni and graphene, reducing As(III), and transferring electrons to the nanoflowers. The nanoflowers then exchange charges with the graphene layer, producing a measurable current. Interference by other ions, such as Pb(II) and Cd(II), was found to be negligible. The proposed method has potential for use as a portable field sensor for monitoring water quality to control hazardous As(III) in human life. [ABSTRACT FROM AUTHOR]

A hybrid-excited doubly salient dual-PM machine (HE-DSDPM) was presented by using the structural multi-tooth modification for an improvement of torque production. The multi-tooth structure modification of HE-DSDPM was clearly described. The PM and stator arcs were further examined for structural optimization. The electromagnetic performance including magnetic flux distribution, flux linkage, back-electromotive force (back-EMF), total harmonic distortion (THD), cogging torque and electromagnetic torque, was investigated with various field current under the same structural constraint. The simulation based on 2-D finite element analysis was used to validate all electromagnetic performance. The results showed that the proposed multi-tooth HE-DSDPM provides the best stator/rotor combination, the appropriate PM characteristics and the enlarged winding slot area. This proposed structure produces better overall electromagnetic performance because of its improved symmetrical magnetic flux path and greater flux regulation quality. In particular, it can generate a larger average torque of 26.18% with the lower ripple torque of about 4% compared to the conventional structure at no field current since the good back-EMF profile and low cogging torque. The largest variance of the torque percentage is occurred when excited by different field currents for the proposed multi-tooth HE-DSDPM. Hence, modification of multi-tooth structure could be beneficial in the electrical machine design of other types of doubly salient structures. [ABSTRACT FROM AUTHOR]

The fast development of electric vehicles (EVs) has resulted in several topics of research in this area, such as the development of a charging pricing strategy, charging control, location of the charging station, and the structure within the charging station. This paper proposes the optimal design of the structure of an EV fast-charging station (EVFCS) connected with a renewable energy source and battery energy storage systems (BESS) by using metaheuristic algorithms. The optimal design of this structure aims to find the number and power of chargers. Moreover, the renewable energy source and BESS can reduce the impact on the grid, so these energy sources are considered as ones of the optimally-designed structure of EVFCS in this work. Thus, it is necessary to determine the optimal sizing of the renewable energy source, BESS, and the grid power connected to EVFCS. This optimal structure can improve the profitability of the station. To solve the optimization problem, three metaheuristic algorithms, including particle swarm optimization (PSO), Salp swarm algorithm (SSA), and arithmetic optimization algorithm (AOA), are adopted. These algorithms aim to find the optimal structure which maximizes the profit of the EVFCS determined by its net present value (NPV), and the results obtained from these algorithms were compared. The results demonstrate that all considered algorithms could find the feasible solutions of the optimal design of the EVFCS structure where PSO provided the best NPV, followed by AOA and SSA. [ABSTRACT FROM AUTHOR]

Flux-switching permanent magnet (FSPM) machines have attracted wide attention in many rotating applications that require high-power density. In this research, we propose for the first time a novel six-phase FSPM generator with a stator featuring a V-shaped flux-focusing magnet arrangement. The design is targeted for low-speed wind power generation. To achieve the design objectives as a wind generator, the highly comprehensive structural parameters, including the number of rotor poles, split ratio, and rotor pole width, are designed and optimized using 2D finite-element analysis. From findings, the optimal stator/rotor pole combination is discovered to be 12/19 for the considered power and speed requirements. When compared to the initial structure, the optimized structure of the V-shaped FSPM generator is found to produce a significant improvement in EMF, cogging torque, electromagnetic torque, power, and efficiency. The power-generating performance of the proposed FSPM generator is found to be outstanding when compared to the radial-flux PM generators described in the literature. Therefore, the proposed V-shaped FSPM generator is capable of being used for low-speed wind power generation. The machine configuration adjustment approach presented in this work can also be utilized for the design of permanent magnet wind generators. [ABSTRACT FROM AUTHOR]

Since the increases in electricity demand, environmental awareness, and power reliability requirements, solutions of single-objective optimal power flow (OPF) and multi-objective OPF (MOOPF) (two or three objectives) problems are inadequate for modern power system management and operation. Solutions to the many-objective OPF (more than three objectives) problems are necessary to meet modern power-system requirements, and an efficient optimization algorithm is needed to solve the problems. This paper presents a many-objective marine predators algorithm (MaMPA) for solving single-objective OPF (SOOPF), multi-objective OPF (MOOPF), and many-objective OPF (MaOPF) problems as this algorithm has been widely used to solve other different problems with many successes, except for MaOPF problems. The marine predators algorithm (MPA) itself cannot solve multi- or many-objective optimization problems, so the non-dominated sorting, crowding mechanism, and leader mechanism are applied to the MPA in this work. The considered objective functions include cost, emission, transmission loss, and voltage stability index (VSI), and the IEEE 30- and 118-bus systems are tested to evaluate the algorithm performance. The results of the SOOPF problem provided by MaMPA are found to be better than various algorithms in the literature where the provided cost of MaMPA is more than that of the compared algorithms for more than 1000 USD/h in the IEEE 118-bus system. The statistical results of MaMPA are investigated and express very high consistency with a very low standard deviation. The Pareto fronts and best-compromised solutions generated by MaMPA for MOOPF and MaOPF problems are compared with various algorithms based on the hypervolume indicator and show superiority over the compared algorithms, especially in the large system. The best-compromised solution of MaMPA for the MaOPF problem is found to be greater than the compared algorithms around 4.30 to 85.23% for the considered objectives in the IEEE 118-bus system. [ABSTRACT FROM AUTHOR]

Indigo blue was discovered as a semiconductor material because of its organic semiconductor properties. This paper shows a primary study of the electrochemical properties of Sakon Nakhon-indigo strain used in the metal–semiconductor–metal (MSM) diode. The fermentation and extraction of our local indigo plant are explained. Indian indigo in the MSM diode is compared in the same conditions of preparation. The electrochemical properties, including the current–voltage (I–V) characteristic, static resistance, and rectification ratio, are discussed. The results show that the electron and hole characteristics and band gap energy of the indigo blue affects the electrochemical properties of the device. Our local MSM diode has a suitable operation between −1 and +3 VMSM with a knee voltage of 1.0 VMSM. Especially, it can produce the highest forward-bias current of about 3.19 mA at linear operation between +2 and +3 VMSM, whereas the review MSM diode is about 2–3 hundred times lower. This shows that this strain has more conductive properties because of its effective electron and hole characteristics obtained by an indigo yield concentration. Therefore, the MSM diode based on Sakon Nakhon-indigo strain is an important role in an electronic semiconductor device for low voltage consumption and high sensitivity. In the future, the molecular characteristics of local indigo may be deeply analyzed to be further developed into a thin-film form used as an organic semiconductor material in several electronic devices. [ABSTRACT FROM AUTHOR]

The rotor permanent magnet flux-switching (RPM-FS) machine is a promising candidate for electric vehicle (EV) and hybrid electric vehicle (HEV) applications. In this paper, we propose the magnetic flux barrier design to improve the torque capability of the RPM-FS machine. The response surface optimization method was used to design and optimize the topology of flux barriers. The 2D finite element analysis shows that the proposed RPM-FS machine has a higher electromotive force than the conventional structure, with only a slight increase in cogging torque. Notably, an insertion of flux barriers could yield a reduction of magnetic flux leakage, an improvement of magnetic saturation capability, and an enhancement of working harmonics of the air-gap flux density. As a result, a significant improvement in torque capability, eddy current losses, and efficiency was obtained. Hence, the RPM-FS machine proposed in this work is capable of being used in EV and HEV applications. [ABSTRACT FROM AUTHOR]

The complexity and uncertainty of power sources connected to transmission networks need to be considered. Planners need information on the sustainability and economics of transmission network expansion planning (TNEP). This work presents a newly proposed method for TNEP that considers high-penetration solar energy by using the particle swarm optimization (PSO) algorithm. The power sources, thermal and hydropower plants, and conditions of load were set in the account, including an uncertain power source and solar energy (PV). The optimal sizing and locating of the PV to be connected to the network were determined by the PSO. The PV grid code was set in the account. The new line's investment cost and equipment was analyzed. The PV cost was considered based on the power loss, and the system's reliability was improved. The IEEE 118 bus test system and Lao PDR's system were requested to test the proposed practice. The results demonstrate that the proposed TNEP method is robust and feasible. The simulation results will be applied to guide the power system planning of Lao PDR. [ABSTRACT FROM AUTHOR]

This work proposes an optimal location and sizing of battery energy storage system (BESS) installation for performance improvement of distribution systems with high distributed generation (DG) penetration level where the DGs comprise photovoltaics (PV) and wind turbines (WT). The installation of the BESS can reduce costs incurred in the systems, alleviate reverse power flow when the systems are in the high DG penetration level, and also achieve peak shaving during high demand. To find the optimal location and sizing of the BESS, three optimization algorithms, genetic algorithm (GA), particle swarm optimization (PSO), and salp swarm algorithm (SSA), are applied, and their performances are compared. The considered objective function is the system costs consisting of transmission loss cost, peak power cost, and voltage deviation cost. The system performance improvement is compared in terms of transmission loss, peak demand, and voltage regulation reductions. IEEE 33- and 69-bus distribution systems with high DG penetration are tested to investigate the performance improvement of the BESS installation. The results found that the installation of the BESS could successfully decrease system cost, improve voltage profile, reduce power losses, alleviate reverse power flow, and achieve peak shaving where PSO and SSA are found to be the best competitive algorithms. So, the proposed method can be further applied to find the optimal location and sizing of the BESS to improve the performance of practical systems in the future. [ABSTRACT FROM AUTHOR]

The doubly salient permanent magnet generator (DSPMG) is widely known as an efficient machine for electrical production from renewable energy. In this paper, we aim to improve the output power of the DSPMG using a structural modification, which is targeted for low-speed electrical generations. Structural parameters including the stator pole depth, thickness of permanent magnet, stator pole arc, and number of winding turns were adjusted, then an optimal value of those parameters was selected based on the characteristics of the generator tested during no-load and on-load conditions. Simulations were based on the finite element method. The generator was targeted to be used for the rated power of 200 W. It was found that the optimally designed generator had a higher electromotive force of 36.1%, a lower cogging torque of 20%, and a higher output power of 12.2% than the conventional structure. The leakage flux of the proposed structure was also improved from the conventional one. Thus, the generator designed in this work could be another capable choice for electrical generation from renewable energy. The proposedly modified technique can also be adapted for output profile improvement of the doubly salient permanent magnet machines which are extensively used for renewable energy production nowadays. [ABSTRACT FROM AUTHOR]

Power quality disturbance (PQD) is an influential situation that significantly declines the reliability of electrical distribution systems. Therefore, PQD classification is an important process for preventing system reliability degradation. This paper introduces a novel algorithm called "adaptive salp swarm algorithm (SSA)" as an optimal feature selection algorithm for PQD classification. Feature extraction and classifier of the proposed classification system were based on the discrete wavelet and the probabilistic neural network, respectively. The classification was focused on the 13 types of power quality signals. The optimal number of selected features for the proposed classification system was firstly determined. Then, it demonstrated that the optimally selected features resulted in the highest classification accuracy of 98.77%. High performance of the proposed classification system in the noisy environment, as well as based on the real dataset was also verified. Furthermore, the proposed SSA indicates a very high convergence rate compared to other well-known algorithms. A comparison of the proposed classification system's performance to existing works was also carried out, revealing that the proposed system's accuracy is on a high-range scale. Hence, the adaptive SSA becomes another efficient optimal feature selection algorithm for PQD classification. [ABSTRACT FROM AUTHOR]

In this work, optimal siting and sizing of a battery energy storage system (BESS) in a distribution network with renewable energy sources (RESs) of distribution network operators (DNO) are presented to reduce the effect of RES fluctuations for power generation reliability and quality. The optimal siting and sizing of the BESS are found by minimizing the costs caused by the voltage deviations, power losses, and peak demands in the distribution network for improving the performance of the distribution network. The simulation results of the BESS installation were evaluated in the IEEE 33-bus distribution network. Genetic algorithm (GA) and particle swarm optimization (PSO) were adopted to solve this optimization problem, and the results obtained from these two algorithms were compared. After the BESS installation in the distribution network, the voltage deviations, power losses, and peak demands were reduced when compared to those of the case without BESS installation. [ABSTRACT FROM AUTHOR]

Featured Application: This work demonstrates the utilization of CD/DVD pick-up heads for scratch inspection on magnetic disk. A non-destructive technique to inspect a scratch on all magnetic disks in the beginning process of hard disk drive (HDD) manufacturing by using CD and DVD pick-up heads as the detector is proposed. It requires a 100% disk inspection of micrometer-sized scratches in a quick measurement with low cost inventing. Most of the previous studies were in static state but this is the first time to be done in dynamic study using the microcontroller in order to promptly serve for industrial utilization. The size, position, and shape characteristic of scratches are examined using light reflection technique. The results show that, when the laser beam is targeted on a magnetic disk in a position, either scratch or non-scratch, the reflected light intensity differs. The DVD pick-up head can detect the width and the surface characteristic of the scratches, which is similar to the results from scanning electron microscope (SEM) for all scratches sizes less than 100 µm. It is also found that using a DVD pick-up head provides a better resolution of shape characteristic and roughness of scratches surface than a CD pick-up head. Hence, the scratch size of 10s µm scale on the magnetic disk can be accurately characterized by this proposed technique, which can be further utilized for magnetic disk inspection in the hard disk drive manufacturing process. [ABSTRACT FROM AUTHOR]

Although several studies have claimed that the current perpendicular-to-the-plane giant magnetoresistance (CPP-GMR) technology is the most attractive technology to achieve ultrahigh capacities of data storage applications, there are still recent studies indicating the inaccuracy of the reading head response caused by the electromagnetic interference (EMI). To improve the precision of the head response, we report a dependence of the physical dimension of CPP-GMR read head on the readback signal distortion due to the EMI. The simulations were based on micromagnetic modeling. The EMI impacts on the head response were analyzed as a function of structural parameters of the head, including the length of stripe height (SH) and read width (RW). Then, the readback characteristics of the head, including the spin-transfer induced noise, power spectral density, and bit-error-rate (BER), were discussed. It was found that an alternation of either SH or RW influences the noise profile. Adjusting the length of RW demonstrates a more influential impact on the noise than that of SH. The frequency spectrum of the head response was also carried out. The physical explanations regarding the results found in this article were given through the behavior of the demagnetization field. The effects of bias current on the head output were additionally investigated. Moreover, the BER of the head with varying the head dimensions was characterized. From findings, the appropriate sizing of the CPP-GMR sensors for an areal density of 1 Tb/in2 was predicted. The results can be utilized to design CPP-GMR read heads at ultrahigh areal densities. [ABSTRACT FROM AUTHOR]

A novel technique is described that has used an ascending and descending swept frequency method to determine a latent failure captured by quasistatic tester (QST) parameters. The parameter disturbances are not sufficient to cause visible damage, but since some of the parameters are over the manufacturing accepted QST values, they might cause a latently failed head.

Nowadays, the changes of economic, environment, and regulations are forcing the electric utilities to operate systems at maximum capacity. Therefore, the operation and control of power system to improve the system stability has been receiving a great deal of attention. This paper presents an approach for enhancing the static voltage stability margin and reducing the power losses of the system with voltage security-constrained optimal power flow (VSC-OPF) that is based on static line voltage stability indices. The control approaches incorporate the voltage stability criteria into the conventional OPF. The minimization of the summation of fast voltage stability index (FVSI), line stability index (Lmn), and line voltage stability index (LVSI) is used as the objective functions. The performance and effectiveness of the proposed control approaches are evaluated on the standard IEEE 30-bus, 57-bus, and 118-bus test systems under normal and contingency conditions. The comparison analysis is carried out with different cases including minimization of generation cost. The proposed control approaches indicate the promising results and offer efficient countermeasures against the voltage instability of the system. [ABSTRACT FROM AUTHOR]

Partitioned stator doubly salient permanent magnet generators (PS-DSPGs) have been extensively used for electrical generation mainly due to their high reliability, high electromotive force (EMF), and high-power output. Therefore, we aim to improve the output power of a PS-DSPG by designing the optimal configuration of generator pole structure. Electrical characteristics including the magnetic flux linkage distribution, phase EMF, cogging torque, voltage regulation, and power output profile were characterized by using the finite element method. After optimizing the generator pole structure including the angle of air gap arc width, it was found that the proposed PS-DSPG with 18/15 (stator/rotor) pole structure with optimized air gap arc width could produce higher EMF of about 23.24% than a conventional structure because this structure has the suitable number of pole structures. Also, an analysis of voltage regulation and power output profiles under the loaded condition were carried out, and it was indicated that the PS-DSPG based on the suitable 18/15-pole structure could provide the best machine performance where the output power is 11.63% higher than the conventional structure. Hence, the proposed PS-DSPG with 18/15-pole structure can appropriately be utilized for electrical generation, especially in low-speed operated generator applications. [ABSTRACT FROM AUTHOR]

Voltage stability is very important, as without it voltage collapse will occur. There is therefore a need to incorporate the consideration of voltage stability into the optimal power flow (OPF). This paper presents a comparison of the effectiveness of five voltage stability indices (VSIs) when incorporated in an OPF. The improved particle swarm optimization (IPSO) algorithm is used to solve the OPF problem. The five VSIs investigated are the L‐index, fast voltage stability index (FVSI), line stability index (Lmn), online voltage stability index (LVSI), and voltage collapse proximity indicator (VCPI). The effectiveness of each VSI is considered in the terms of the generation cost, emission, transmission loss, and voltage stability. The IEEE standard 14‐, 30‐, 57‐, and 118‐bus test systems are used for the comparison. It is found that considering each voltage stability index as part of the objective function for the OPF provided different values of generation cost, emission, transmission loss, and maximum loadability. The results suggest that FVSI and Lmn provide the minimum generation cost values for all test systems, while VCPI and LVSI provide lower emission values for most systems. VCPI gives the lowest transmission losses for all systems, and the L‐index provides the maximum loadability for most systems. Incorporation of these indices into the OPF can provide the optimal values in different terms, and the most suitable voltage stability index will depend on the situation and size of the system, which needs to be judiciously chosen. © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

Photovoltaic (PV) systems are one of the most popular technologies to produce electricity from renewable energy, which can efficiently accommodate electricity demand. However, there are some issues occurring at high PV penetration levels in the distribution system. In order to increase the PV penetration level, battery energy storage system (BESS) has been widely integrated with PV systems because it could overcome issues during high PV penetration level and greatly provide optimal energy management. Then, this paper aims to increase the PV penetration level in low voltage (LV) distribution system by installation of BESS. The 41-bus practical radial LV distribution system located in Ratchaburi province, Thailand was focused. The net present value (NPV) was used as an economic indicator indicating the profitability of installing BESS. The optimal sitting, sizing, and operation of BESS yielding the maximum total NPV were determined. Then, the maximum PV penetration level was predicted for 10 case studies. In addition, the method for flattening load profile was appropriately adapted to be used in the LV distribution system. The genetic algorithm (GA) was performed to solve the optimization problem. The results showed that total NPV was increased with increasing the PV penetration level. The PV penetration level of 130% was found to be a suitable value for this particular system, which could provide significant improvement in NPV compared to the conventional system. The optimal BESS sizing and siting including the optimal BESS operation were also demonstrated. [ABSTRACT FROM AUTHOR]

Design of a simple and compact dual frequency monopole antenna for applications in PCS (Personal Communication System) and Bluetooth system is presented. The first operating frequency is achieved from a traditional monopole antenna structure for the frequency of 1.9 GHz for PCS application while the second operating frequency is obtained from two spurline structures etched on the traditional monopole antenna structure for the frequency of 2.4 GHz for Bluetooth application. Both simulated and experimental results, such as reflection coefficients and VSWR (Voltage Standing Wave Ratio), are presented and discussed. The radiation pattern measurements are also performed. From the measured results, the first operating band covers between 1.851 and 1.98 GHz, and the second operating band covers between 2.28 and 2.53 GHz. The proposed antenna is compact and suitable to be used for applications in the PCS and Bluetooth system. [ABSTRACT FROM AUTHOR]

The spin transfer induced magnetization switching in current perpendicular-to-the-plane spin valve nanopillar based Co2FeAl0.5Si0.5 Heusler alloy with varying the initial angles of the magnetization of sensing layer, θ0, was investigated via macrospin simulations. The effects of an in-plane magnetic field, Hi, on the switching behavior were also evaluated. The magnetization switching was excited by spin polarized switching current, Is. The time varying magnetization was computed by the Landau-Lifshitz-Gilbert-Slonczewski equation, while the spin transfer induced noise was examined by using the power spectral density analysis. It was found that θ0 should be narrowly initialized since this configuration produces the small noise during the switching. Also, the negative Is produced more uniform switching than the positive Is due to existence of ferromagnetic exchange coupling. When Hi was presented, the noise generated at low frequencies could be suppressed, and then the switching behavior became more uniform. In addition, the results indicated that the noise configuration could be explained by the physical dynamic of magnetization behavior. Hence, the spin transfer induced noise needs to be minimized in order to improve the performance of spin transfer torque random access memory for high density recording. [ABSTRACT FROM AUTHOR]

Recently, the increase in high areal density of hard disk drive with the small bit cells affects the structural variation in the magnetic recording head. Therefore, the structural size effect on the altered temperature in the tunneling magetoresistance (TMR) head with the MgO-based magnetic tunnel junction structure was investigated. Results indicate that the temperature increment in the MgO layer and the antiferromagetic layer decreases significantly with decreasing the thickness of the MgO barrier. This is because the generated heat during the current flow is proportional to the TMR resistance which can be estimated by the resistance of the MgO barrier layer. The efficiency of the write/read process with the thermal effect in the magnetic recording head is the important parameter realized for development of the storage technology. [ABSTRACT FROM AUTHOR]

Exchange coupled composite bit patterned media (ECC-BPM) are one candidate to solve the trilemma issues, overcome superparamagnetic limitations, and obtain ultrahigh areal density. In this work, the ECC continuous media and ECC-BPM of Fe/L10-FePt/Fe trilayer schemes are proposed and investigated based on the Landau-Lifshitz-Gilbert equation. The switching field, Hsw, of the hard phase in the proposed continuous ECC trilayer media structure is reduced below the maximum write head field at interlayer exchange coupling between hard and soft phases, Aex, higher than 20 pJ/m and its value is lower than that for continuous L10-FePt single layer media and L10-FePt/Fe bilayer. Furthermore, the Hsw of the proposed ECC-BPM is lower than the maximum write head field with exchange coupling coefficient between neighboring dots of 5 pJ/m and Aex over 10 pJ/m. Therefore, the proposed ECC-BPM trilayer has the highest potential and is suitable for ultrahigh areal density magnetic recording technology at ultrahigh areal density. The results of this work may be gainful idea for nanopatterning in magnetic media nanotechnology. [ABSTRACT FROM AUTHOR]

ABSTRACT In this paper, we propose a modified high rate (3, L) quasi-cyclic low-density parity-check (QC-LDPC) code based on circulant permutation matrices for efficient encoder implementation. The structure of the code is modified from a (3, L) regular QC-LDPC code to be an approximate lower triangular matrix and a linear independent form. We present two novel efficient encoding techniques for generating redundant parity bits. The complexity of the encoder implementation depends on the number of redundant parity bits of the code for one-stage encoding and the length of the code for two-stage encoding. The advantage of both encoding techniques is that few XOR gates are used in encoder implementation. The simulation results show that the proposed codes at code rate 0.884 and 0.953 have good bit error rate performance compared with other LDPC codes over PR2 and EPR2 channels. European Transactions on Telecommunications. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

ABSTRACT As the areal density rapidly changes, the signal reflection increases. In order to avoid the reflection between a magnetic recording head and a read/write driver on hard disk drive interconnects (HDDIs), the windowing technique is used to keep low insertion loss and it causes the higher crosstalk between lines. In this work, the crosstalk on idealized HDDI with windowing is investigated. The crosstalk represented by the scattering parameters calculated by using the full wave simulation software based on finite integral technique. From the results, the improvement of insertion loss and transmission bandwidth (−3 dB bandwidth) can be found when the window percentage is increased. For the 90% windowed structure, these are improved as 4.27 dB at 1 GHz and 4.53 GHz comparing with the conventional structure, respectively. Besides, the crosstalk increases with the increasing of window percentage. However, it can be suppressed up to 5.68 dB in a range of 0.24-1 GHz when the window percentage is 90%. Furthermore, the 90% of windowed structure with 8 mm window pitch possess the lowest crosstalk about 30.22 dB in a range of 0.32-6.4 GHz. In addition, the placing position of windows in a reference plane with a half of the rest length at both ends should be avoided because it increases both crosstalk and insertion loss. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:217-222, 2014. [ABSTRACT FROM AUTHOR]

Scratch damage on magnetic disks is a major problem in the hard drive industry as it affects the reliability. To address this problem, it is therefore necessary to apply advanced detection techniques. To enhance micro-scratch detection, an infrared camera capturing technique based on heat radiation is proposed in this article. Nevertheless, the captured thermal images may be invisible due to the Narcissus effect as a dark region covering the interested areas. An approach of thermal image refinement is also presented by heating the magnetic disk at various angles of magnetic disk and CaF2external zoom lens. The thermal image and the emissivity ratio are used to indicate suitable angles and heating times at which the scratch can be clearly detected. It is found that the rotation of the CaF2external zoom lens can assist the detection of a micro-sized scratch and a heating time of 10 s is sufficient to clearly show scratches if the magnetic disk is set to be aligned in parallel with the CaF2external zoom lens. [ABSTRACT FROM AUTHOR]

Due to the increasing data transfer rates in hard disk drives, the crosstalk has become a source of operation failures during electrical and magnetic testing. In order to reduce this detrimental effect, the differential mode signal system of high-speed and high-density interconnects based on a new magnetic technique is proposed. The scattering parameters are evaluated in terms of the crosstalk and the transmission parameters, and then calculated using the 3D full wave simulation software. From the results, it is found that the proposed technique can suppress the near-end crosstalk and far-end crosstalk in a wide range of 1-20 GHz. In addition, the transmission signal levels from the proposed structure are still comparable to the conventional structure. Hence, the proposed technique provides an effective reduction of crosstalk, while maintaining the comparable transmission signal in a wide range of frequency. [ABSTRACT FROM AUTHOR]

Recently, there has been a growing interest in the effects of electrostatic discharge (ESD) failure on tunneling magnetoresistive (TMR) recording heads because it directly affects reliability in manufacturing of these heads. Therefore, we study the magnetic degradation in TMR junctions caused by the temperature increase using three different ESD models. A 3-D finite-element method is used for analyzing the spatial and temporal profiles of the temperature during the discharge. The results from the three models show that, although the highest temperature occurs in the MgO barrier layer, the initial magnetic modification likely arises in the IrMn antiferromagnetic layer due to its low Néel temperature. We also found that the increase in temperature is proportional to the square of the ESD voltage. The magnetic instability of the antiferromagnetic layer due to the ESD effect is the important parameter realized for development of the future TMR devices. [ABSTRACT FROM PUBLISHER]

Electrostatic Discharge (ESD) effects have been identified as one of the most dangerous causes of giant magnetoresistive (GMR) recording head damage. These phenomena have been studied at all levels of hard-disk drive manufacturing 1. The head gimbal assembly (HGA) is mainly studied because of its exposure to the environment. The standard models are typically based on the human body model (HBM), the machine model (MM) and the charged device model (CDM) where research and practical tests are incompatible. In production, one or more ESD models are normally effective while the other is undergone under a separate model. In addition, tests in the time domain are more accurate than those in the frequency domain. However, picosecond measurements are taken with difficulty where the frequency domain measurement provides non-real time results. Therefore, this is the first report of serial ESD detection using the new technique of wavelet transform. It has been found that the glitch occurs when the ESD level of HBM – MM and HBM – CDM serial ESD on GMR heads are in the ranges of 1.2-2.6 V and 12-15 V respectively. [ABSTRACT FROM AUTHOR]

Electrostatic discharge (ESD) effects on GMR recording heads have been reported as the major cause of head failure. Since the information density in hard-disk drives has dramatically increased, the GMR head will be no longer in use. The tunneling magnetoresistive (TMR) read heads are initially introduced for a 100 Gbit/in2 density or more. Though the failure mechanism of ESD in GMR recording heads has not been explicitly understood in detail, a study to protect from this effect has to be done. As the TMR head has been commercially started, the ESD effect must be considered. This is the first time that the TMR equivalent circuit has been reported in order to evaluate the ESD effect. A standard human body model (HBM) is discharged across R+ and R- where the capacitances of flex on suspension (FOS) are varied. It is intriguingly found that the electrical characteristics of the TMR head during the discharge period depend on the discharge position. This may be explained in terms of the asymmetry impedance of TMR by using adapted Thevenin's theory. The effect of FOS components on TMR recording heads is also discussed. [ABSTRACT FROM AUTHOR]

This article presents the effect of Radio Frequency Identification (RFID) at 125 kHz on GMR recording heads. The study is mainly concerned with the RFID effect on recording heads in terms of the distance (r) between the antenna reader of the RFID and the recording head, the coil radius (a) of the antenna reader, and the angle (θ) between antenna reader and recording head. The maximum error of the writing current is found in this experiment of about 2.5% (where r < a). An increase of angle affects the writing current error when the radius increases. It is found that the writing current error decreases when r > a. SEM result shows that radiated fields of RFID do not visibly degrade the writer part but only disturbance to recording heads in testing is found. [ABSTRACT FROM AUTHOR]

This works reports, for the first time, the thorough study and optimisation of Phase Change Memory (PCM) structure with thin metal inserted chalcogenide via electrical resistivity (ρ) using finite element modeling. PCM is one of the best candidates for next generation non-volatile memory. It has received much attention recently due to its fast write speed, non-destructive readout, superb scalability, and great compatibility with current silicon-based mass fabrication. The setback of PCM is a high reset current typically higher than 1mA based on 180nm lithography. To reduce the reset current and to solve the over-programming failure, PCM with thin metal inserted chalcogenide (bottom chalcogenide/metal inserted/top chalcogenide) structure has been proposed. Nevertheless, reports on optimisation of the electrical resistivity using the finite element method for this new PCM structure have never been published. This work aims to minimize the reset current of this PCM structure by optimizing the level of the electrical resistivity of the PCM profile using the finite element approach. This work clearly shows that PCM characteristics are strongly affected by the electrical resistivity. The 2-D simulation results reveal clearly that the best thermal transfer of and self-joule-heating at the bottom chalcogenide layer can be achieved under conditions; ρ_bottom chalcogenide > ρ_metal inserted > ρ_top chalcogenide More specifically, the optimized electrical resistivity of PCMTMI is attained with ρ_top chalcogenide: ρ_metal inserted: ρ_bottom chalcogenide ratio of 1:6:16 when ρ_top chalcogenide is 10-3 Ωm. In conclusion, high energy efficiency can be obtained with the reset current as low as 0.3mA and with high speed operation of less than 30ns. [ABSTRACT FROM AUTHOR]

In this work, we propose exchange-coupled-composite-bit-patterned media (ECC-BPM) with microwave-assisted magnetic recording (MAMR) to improve the writability of the magnetic media at a 4 Tb/in2 recording density. The suitable values of the applied microwave field's frequency and the exchange coupling between magnetic dots, Adot, of the proposed media were evaluated. It was found that the magnitude of the switching field, Hsw, of the bilayer ECC-BPM is significantly lower than that of a conventional BPM. Additionally, using the MAMR enables further reduction of Hsw of the ECC-BPM. The suitable frequency of the applied microwave field for the proposed media is 5 GHz. The dependence of Adot on the Hsw was additionally examined, showing that the Adot of 0.14 pJ/m is the most suitable value for the proposed bilayer ECC-BPM. The physical explanation of the Hsw of the media under a variation of MAMR and Adot was given. Hysteresis loops and the magnetic domain of the media were characterized to provide further details on the results. The lowest Hsw found in our proposed media is 12.2 kOe, achieved by the bilayer ECC-BPM with an Adot of 0.14 pJ/m using a 5 GHz MAMR. [ABSTRACT FROM AUTHOR]

Current-perpendicular-to-the-plane giant magnetoresistance (CPP-GMR) read sensors based on Heusler alloys are promising candidates for ultrahigh areal densities of magnetic data storage technology. In particular, the thickness of reader structures is one of the key factors for the development of practical CPP-GMR sensors. In this research, we studied the dependence of the free layer thickness on the stability of the Co2(Mn0.6Fe0.4)Ge Heusler-based CPP-GMR read head for an areal density of 1 Tb/in2, aiming to determine the appropriate layer thickness. The evaluations were done through simulations based on micromagnetic modelling. The reader stability indicators, including the magnetoresistance (MR) ratio, readback signal, dibit response asymmetry parameter, and power spectral density profile, were characterized and discussed. Our analysis demonstrates that the reader with a free layer thickness of 3 nm indicates the best stability performance for this particular head. A reasonably large MR ratio of 26% was obtained by the reader having this suitable layer thickness. The findings can be utilized to improve the design of the CPP-GMR reader for use in ultrahigh magnetic recording densities. [ABSTRACT FROM AUTHOR]

Solving the optimal power flow problems (OPF) is an important step in optimally dispatching the generation with the considered objective functions. A single-objective function is inadequate for modern power systems, required high-performance generation, so the problem becomes multi-objective optimal power flow (MOOPF). Although the MOOPF problem has been widely solved by many algorithms, new solutions are still required to obtain better performance of generation. Slime mould algorithm (SMA) is a recently proposed metaheuristic algorithm that has been applied to solve several optimization problems in different fields, except the MOOPF problem, while it outperforms various algorithms. Thus, this paper proposes solving MOOPF problems based on SMA considering cost, emission, and transmission line loss as part of the objective functions in a power system. The IEEE 30-, 57-, and 118-bus systems are used to investigate the performance of the SMA on solving MOOPF problems. The objective values generated by SMA are compared with those of other algorithms in the literature. The simulation results show that SMA provides better solutions than many other algorithms in the literature, and the Pareto fronts presenting multi-objective solutions can be efficiently obtained. [ABSTRACT FROM AUTHOR]

Power quality disturbance (PQD) is an important issue in electrical distribution systems that needs to be detected promptly and identified to prevent the degradation of system reliability. This work proposes a PQD classification using a novel algorithm, comprised of the artificial bee colony (ABC) and the particle swarm optimization (PSO) algorithms, called "adaptive ABC-PSO" as the feature selection algorithm. The proposed adaptive technique is applied to a combination of ABC and PSO algorithms, and then used as the feature selection algorithm. A discrete wavelet transform is used as the feature extraction method, and a probabilistic neural network is used as the classifier. We found that the highest classification accuracy (99.31%) could be achieved through nine optimally selected features out of all 72 extracted features. Moreover, the proposed PQD classification system demonstrated high performance in a noisy environment, as well as the real distribution system. When comparing the presented PQD classification system's performance to previous studies, PQD classification accuracy using adaptive ABC-PSO as the optimal feature selection algorithm is considered to be at a high-range scale; therefore, the adaptive ABC-PSO algorithm can be used to classify the PQD in a practical electrical distribution system. [ABSTRACT FROM AUTHOR]