Extra Power Research Articles

Evaluation of the amount of residual monomer released from different flowable composite resins

Today, resin materials are used in the restoration of permanent and deciduous teeth or as fissure sealants. The materials can contain different types of monomers (Bis-GMA, UDMA, TEGDMA). These monomers can be released into the oral cavity after polymerization. Residual monomers released from resin-containing restorative materials after polymerization have been reported to have negative effects on mechanical properties. The aim of our study is to evaluate the amount of residual monomers released after polymerization of different flowable composite resin materials using two different modes of LED light source. Composite disc samples (8 mm diameter/2 mm depth) prepared for each material group were polymerized using two different modes of the LED light device (Standard mode and extra power mode). HPLC (High Performance Liquid Chromatography) device was used to measure the amount of residual monomer release at 1 h, 1 day, 3 days and 7 days periods. Pairwise comparison of the differences between the materials was performed by Post-hoc test. For each residual monomer, the Kruskal Wallis test was used to analyze the difference between the materials in standard mode and the difference between the materials in extra power mode. According to the results of the study; Grandio flow flowable composite showed the highest release of TEGDMA and Bis-GMA while SDR® Flow flowable composite showed the lowest release of TEGDMA, Bis-GMA and UDMA. For all materials, the extra power mode resulted in more residual monomer release. TEGDMA and Bis-GMA release was detected in all tested flowable composites at all time periods.

Construction and remote demonstration of an inexpensive but efficient experimental setup for studying self-inductance and mutual-inductance between two coils

Measurement of self-inductance and mutual-inductance has been demonstrated as a laboratory experiment with great simplicity. The novelty of this demonstration lies in its straightforward circuitry and methodology, enabling the experiment accessible to students with minimal prerequisite knowledge. A coil-pair setup was constructed using discarded common household articles, costing very low but provides high quality throughput in teaching-learning experience. The demonstration can be easily conducted online using a laptop without the need of extra power supply. The experiment suits for high school and pre-university students, as evident by twenty first-semester undergraduate physics and electronics students who found it both satisfying and enjoyable with a relatively flat learning curve.

Infrastructure Barriers to Islamic Political Parties: Dynamics of PKB in the 2004-2019 Presidential Election Contestation

This research was intended to determine the infrastructural barriers of the PKB political party in encouraging its cadres to become contestants in the presidential and vice-presidential elections from 2004 to 2019. During the four presidential and vice-presidential elections, PKB, one of Indonesia's largest Islamic parties, was absent from sending its cadres as contestants. This failure is suspected to result from infrastructural obstacles that intersect with PBNU's political interests. This research used a qualitative approach by combining interviews with documentation data and direct observations in the field. Interview data findings were used as a guide for finding online or offline documentation data. Both findings confirmed each other and were combined with observational data as a data validation method. Data presentation was carried out in three main stages. Namely, data findings were reduced according to research needs and elaborated using Anthony Giddens' structuration thinking. The data findings in this research reveal that there are infrastructural obstacles in the form of organizational patrons that disrupt the independence of PKB. There is also extra organizational power from the NU autonomous division, which is suspected to have sectoral interests. Apart from that, external intervention makes PKB's political steps less flexible.

On the coupling effect in the RF-biased inductively coupled plasma with the synchronous control

The coupling effects between the bias power and the inductive power in the RF-biased inductively coupled plasma with synchronous control are investigated by measuring electron energy distribution function using a compensated Langmuir probe. With synchronous control, the inductive power and the bias power are driven at an identical phase and frequency. The experimental results show that the inductive power lowers the self-bias voltage, while the bias power changes the plasma density by introducing extra power absorption and dissipation. The bias power also enhances the electron beam confinement, leading to an increase in electron density at a low pressure. Furthermore, in the E and H mode transition, with the bias power increasing, the hysteresis power reduces, and the electron density jump decreases.

Observation of GRB 221009A Early Afterglow in X-Ray/Gamma-Ray Energy Bands

The early afterglow of a gamma-ray burst (GRB) can provide critical information on the jet and progenitor of the GRB. The extreme brightness of GRB 221009A allows us to probe its early afterglow in unprecedented detail. In this Letter, we report comprehensive observation results of the early afterglow of GRB 221009A (from T 0+660 s to T 0+1860 s, where T 0 is the Insight-HXMT/HE trigger time) in X-ray/gamma-ray energy band (from 20 keV to 20 MeV) by Insight-HXMT High Energy X-ray Telescope, GECAM-C, and Fermi/Gamma-ray Burst Monitor. We find that the spectrum of the early afterglow in 20 keV–20 MeV can be well described by a cutoff power law with an extra power law that dominates the low- and high-energy bands, respectively. The cutoff power law E peak is ∼30 keV, and the power-law photon index is ∼1.8 throughout the early afterglow phase. By fitting the light curves in different energy bands, we find that a significant achromatic break (from keV to TeV) is required at T 0 + 1246−26+27 s (i.e., 1021 s since the afterglow starting time T AG = T 0+225 s), providing compelling evidence of a jet break. Interestingly, both the pre-break and post-break decay slopes vary with energy, and these two slopes become closer in the lower energy band, making the break less identifiable. Intriguingly, the spectrum of the early afterglow experienced a slight hardening before the break and a softening after the break. These results provide new insights into the physics of this remarkable GRB.

A real-time energy flow management of a grid-connected renewable energy sources-based EV charging station

ABSTRACT As the sales of electric vehicles (EVs) increase in India, there will be an increase in the number of charging stations in the future. Meanwhile, the demand for extra power from the grid and intermittent power from renewable energy presents significant challenges for charging infrastructure. This paper presents a real-time energy flow management strategy (EFMS) designed for an EV charging station (EVCS) that utilises power from renewable energy sources (RES), an energy storage battery unit (ESBU), and the grid. The primary objective is to increase the utilisation of renewable energy and minimise the quantity of electricity bought during the peak period of the grid by implementing direct electric vehicle load control. EVCS has been designed to charge up to 80 EVs using five DC chargers. The EFMS aims to enhance the scheduling of EV charging by considering grid time-of-use (ToU) pricing and efficient usage of ESBU in terms of battery degradation effect and maximising the use of RES. A multi-objective optimisation algorithm has been developed for EV scheduling. The baseline uncoordinated charge method is contrasted with the proposed approach. The EFMS effectiveness is tested in MATLAB, and the subsequent analysis and results are drawn and discussed.

A Chaos-FFH Based Approach Against Illegal Intelligent Reflecting Surface (IIRS) Based Jamming Attacks

Illegal intelligent reflecting surfaces (I- IRSs), i.e., the illegal deployment and utilization of IRSs, impose serious harmful impacts on wireless networks. The existing I-IRS-based illegal jammer (IJ) requires channel state information (CSI) or extra power or both, and therefore, the I-IRS- based IJ seems to be difficult to implement in practical wireless networks. Due to continued sharing of resources, wireless networks often come under security attacks, most common of which are eavesdropping attacks. In the case of eavesdropping attacks, deliberately designed random eavesdropping data is added to the channel. These eavesdropping along with noise result in packet losses and low throughput, degrading the overall performance of the cognitive network. In this work, a security aware jamming and eavesdropping rejection mechanism is proposed which detects suspicious signals in the channel frequency response and employs discrete equalization to recover transmitted data. The proposed approach uses a chaos based FFH protocol for possible adversarial eavesdropping attacks. The error rate and average sum rate show that the proposed system outperforms the exiting systems in terms of the performance metrics. Keywords:- Illegal Intelligent Reflecting Surface (IIRS), Jamming Attack, Packet Intercept. Error Rate, Sum Rate

A precision current sensing circuit with chopper amplifier of symmetric topology

Precision current detection is essential in smart power switches. In this paper, a current-sensing amplifier with symmetric topology is presented, which adopts the chopping technique to improve sensing accuracy. This design offers four advantages at the same time. Firstly, the rail-to-rail complementary differential pairs are achieved to obtain a full input voltage swing, and the Class AB output stage is incorporated to increase the slew rate. Secondly, symmetric topology with the current shunt source provides moderate gain enhancement without extra power consumption and further increases the gain bandwidth product. Thirdly, the chopping technique is applied to achieve a significant reduction in the amplifier's input offset without an extra low pass filter. Fourthly, the constant GM-C biasing circuit is introduced to improve the robustness of system response and current sensing accuracy under process variations. The four advantages can be substantiated through the application of a 0.5-μm BCD technology process, with multiple simulation results, including frequency responses and current sensing accuracy in process corners and temperature variations. The mismatch Monte-Carlo and noise analyses are also conducted with the chopper on or off. Chip experimental results show that the current sensing error is within ±1.6 % from 0.01 A to 3 A load current. Furthermore, multiple tests have been conducted to determine the absolute values of the input offset voltages, ranging between 20 μV and 50 μV, which is a relatively small amount to vastly improve the sensing accuracy.

An Efficient Hybrid Energy Smart System Using Lithium Ion Batteries Integrated with Battery Management System

The use of rechargeable batteries to store and distribute extra energy from photovoltaics (PV) improves the efficiency of solar energy generation. This study constructs a solar power plant system that is linked to the grid network and includes battery energy storage. The efficiency of a hybrid solar power plant with integrated batteries and grid energy storage is demonstrated and evaluated in this study. This study is based on real-time testing to determine battery utilization when different electrical loads for office use are combined. The workload profile during peak hours of use, which correspond to the peak time of sunshine, is used to evaluate the system. The collected findings show that the degree of effectiveness of this hybrid power plant fulfills the power simulation. During the peak irradiation time, the maximum power is 2100 watts, whereas the needed power simulation, which is 1900 watts in this case, so the power efficiency percentage is 110.52%. It means that PV can satisfy the charged power while also supplying extra power to the battery for usage at low periods. During the 8-hour test, the calculation of cost savings revealed a savings in electricity expenditure of Rp. 14,373. The energy storage system's real operational needs were met by battery storage and PV.

Disco Intelligent Reflecting Surfaces: Active Channel Aging for Fully-Passive Jamming Attack

Due to the open communications environment in wireless channels, wireless networks are vulnerable to jamming attacks. However, existing approaches for jamming rely on knowledge of the legitimate users’ (LUs’) channels, extra jamming power, or both. To raise concerns about the potential threats posed by illegitimate intelligent reflecting surfaces (IRSs), we propose an alternative method to launch jamming attacks on LUs without either LU channel state information (CSI) or jamming power. The proposed approach employs an adversarial IRS with random phase shifts, referred to as a “disco” IRS (DIRS), that acts like a “disco ball” to actively age the LUs’ channels. Such active channel aging (ACA) interference can be used to launch jamming attacks on multi-user multiple-input single-output (MU-MISO) systems. The proposed DIRS-based fully-passive jammer (FPJ) can jam LUs with no additional jamming power or knowledge of the LU CSI, and it can not be mitigated by classical anti-jamming approaches. A theoretical analysis of the proposed DIRS-based FPJ that provides an evaluation of the DIRS-based jamming attacks is derived. Based on this detailed theoretical analysis, some unique properties of the proposed DIRS-based FPJ can be obtained. Furthermore, a design example of the proposed DIRS-based FPJ based on one-bit quantization of the IRS phases is demonstrated to be sufficient for implementing the jamming attack. In addition, numerical results are provided to show the effectiveness of the derived theoretical analysis and the jamming impact of the proposed DIRS-based FPJ.

Joint Design of Long-Term Base Station Activation and Short-Term Beamforming for Green Wireless Networks

Base station (BS) activation is a widely-used approach to alleviate the system power cost for device maintenance. However, frequently switching on/off BSs may also introduce extra power and signaling costs, which motivates us to limit the BS switching frequency when performing BS activation. To address this, we study a problem of joint long-term BS activation and short-term beamforming (J-LTBA-STBF) in a network where multiple multi-antenna BSs cooperatively serve multiple single-antenna users. LTBA means that each BS’s active/inactive switching frequency is properly controlled to yield relatively stable BS-user association and limited switching power, while STBF lies in that due to the low cost of refreshing beamformers, the transmit beamformers are allowed to be updated frequently to maximally lower the transmit power. Following the idea, two efficient algorithms are designed, according to the data amount they request to start running, to optimize the active BSs and the BS transmit beamformers in multiple adjacent time slices. Consequently, the transmit, maintenance and switching powers can be well balanced to facilitate power-efficient communications. Numerical results validate the efficacies of the algorithms.

A New Framework of RIS-Aided User-Centric Cell-Free Massive MIMO System for IoT Networks

With its merit of inter-cell interference elimination and enhanced throughput, cell-free (CF) massive multiple-input multiple-output (MIMO) system, has attracted considerable interests in evolution of 6G Internet-of-Things (IoT) networks. Meanwhile, reconfigurable intelligent surface (RIS) has shown its potential benefit in enhancing both capacity and energy efficiency (EE). In this paper, a new framework of RIS-aided CF massive MIMO system is proposed for IoT networks, in which extra active APs are deployed closely to the passive RISs, in that way, the RIS-user channels can be approximately obtained by parameters estimated at those extra APs with acceptable loss. To avoid extra power consumption, user-centric AP selection strategy in CF system is suggested, on the basis of which, an optimization problem related to power control, precoding and RIS phase shift is formulated to maximize the sum rate. To deal with this tough three-variable optimization, a Lagrangian dual transformation and fractional programming based algorithm is proposed. In particular, the proposed algorithm can extend to optimize EE and well adapt to other RIS-aided CF systems. Simulation results reveal that the proposed algorithm can achieve superior performance in terms of both sum rate (SR) and EE.

Decentralized control strategies for resilient power systems using multi-agent systems

The study examines the use of Multi-Agent Systems (MAS) in decentralized control mechanisms to improve the resilience of power systems. The analysis included simulations, agent interactions, and system dynamics. The results demonstrate the durability of Generator 001 in City A, as it constantly maintains an average power production of 46.5 MW. On the other hand, Generator 002 in City B regularly generates around 29 MW. Storage Unit 003 efficiently fulfills requests by distributing 15 MW upon receiving a prompt from Generator 001. The system is notably influenced by consumer behavior, as seen by Consumer 004 in City C consistently demanding 31 MW. Significantly, when Consumer 005 is activated, it increases demand to 27.5 MW. An examination of percentage variations indicates little swings in generator outputs at peak times, underscoring their stability. Nevertheless, consumer engagement during periods of high demand results in significant surges in the need for resources. The agents demonstrate effective communication by swiftly acknowledging and fulfilling requests for extra power. The results emphasize the potential of MAS as a viable framework for effectively distributing resources and coordinating various agents. This research provides useful insights into adaptive solutions for effectively managing changing power system circumstances. It highlights the crucial role of Multi-Agent Systems (MAS) in maintaining stability, maximizing the use of resources, and meeting the developing energy needs.

Line Congestion Management in Modern Power Systems: A Case Study of Pakistan

The surging electricity demand in Pakistan has led to frequent blackouts, prompting government initiatives to expand power plant capacities and improve the national grid. The government prioritizes integrating large‐scale renewable energy sources, such as wind and solar power, to reduce dependence on conventional power plants. However, the intermittency of renewables leads to forecasting errors, requiring extra power reserves from conventional units, thereby escalating operational costs and CO2 emissions. The country currently utilizes a manual mechanism for power balancing operations, overlooking critical grid constraints of the transmission line loadings. In such conditions, injecting large‐scale power from renewables can lead to significant fluctuations in line power flows, risking transmission line loadings and compromising the system’s secure operation. Hence, this paper has developed an automatic generation control (AGC) model for the highly wind‐integrated power system to alleviate line congestions in the network and enhance the economic operation of the system. The study utilizes the Pakistan power system as a case study to simulate the proposed model. The developed real‐time power dispatch strategy for the AGC system considers the constraints of the transmission line to avoid congestion. It integrates wind energy as operating reserves to enhance the economic operation of the system. When managing line congestion, it identifies overloaded bus lines and adjusts power regulation accordingly while compensating for shortfalls by augmenting transmitted power from regional grid stations. However, it maintains a constant dispatch ratio without line overloads, aligned with generation capacities. Additionally, the strategy integrates reserve power from the wind power plant and traditional generating units to further improve economic operations. Simulations have been conducted using PowerFactory software, employing the eight‐bus and five‐machine models to replicate the characteristics of the Pakistan power system. The results demonstrate the effectiveness of the proposed AGC design in mitigating transmission line congestion of power systems that are heavily integrated with wind energy sources while simultaneously ensuring the economic operation of generating units.

The Comparison of the Sunscreen Activity of Ethanol Extracts and Fractions from Robusta Coffee (Coffea canephora) Leaves using UV Spectrophotometer Method

Background: The development of sunscreen preparations has led to the use of natural ingredients as active substances. Robusta coffee leaves (Coffea canephora) contain alkaloids, flavonoids, saponins, tannins and steroids. From previous research the SPF value of its ethanol extract at 150 ppm was 12,989 (Maximum protection). The sunscreen activity of its fractions need to be determined, to find out which one has the highest potential sunscreen activities
 Method: Sunscreen activity examination was carried out in vitro using a UV spectrophotometer. The concetntration of each fraction used was 150 ppm.
 Results: The N-hexane, ethyl acetate and butanol fractions have sunscreen activity with extra protective power, SPF values respectively were 6.006, 7.609, and 8.046. This activities arises from the content of flavonoids, phenolics and tannins. While the remaining water fraction has the lowest protective activity, with SPF value 3.985 and only contain tannin. Compared to Its ethanol extract, the ethanol extract has better sunscreen activit, because at a 150 ppm it has SPF value 12.989 (Maximum sunscreen activity)
 Conclusion: the sunscreen activity of this fraction is lower than its ethanol extract. The ethanol extract of robusta coffee leaves has more potential to be developed into a sunscreen preparation.
 Keywords: ; Robusta coffee leaves ; Fraction ; SPF Value

Extraction of Fringing-Effect Power Loss from Total Dissipation in Magnetic Component

Power magnetics in the energy storage configuration are not able to handle a significant amount of power without the introduction of a physical discontinuity in their magnetic path. This frequently takes the form of a discrete air gap giving rise to certain consequences such as extra power dissipation in the coils mounted on gapped cores. The ascertainment of the impact of the fringing magnetic field at the air gap on the efficiency of power conversion is highly problematic due to the complex nature of the phenomenon. The fringing-effect power loss typically coexists and is combined with all the other power-dissipation mechanisms, which greatly complicates the extraction of losses brought about solely by the fringing flux at the air gap from the total amount of dissipation in a given magnetic component. Magnetic cores of composite materials do not require a discrete air gap, as the air gap in them is distributed throughout the entire material, thus preventing the fringing magnetic flux from forming. However, there is a downside to this approach, as power loss in the material is comparably greater and so are the manufacturing costs. As shown here, distributed-gap-type core materials, due to the absence of physical discontinuity, and hence the lack of registerable fringing-effect power loss, can be utilized to comparatively ascertain and extract the extra power dissipation due to the fringing effect phenomenon in gapped magnetic components.

Consolidation of LVFRT capabilities of microgrids using energy storage devices

The performance and dependability of distribution networks may be enhanced by the incorporation of microgrids (MGs). However, it is necessary to enhance low voltage fault-ride-through (LVFRT), which has the capacity to prevent abrupt grid disconnections during LV occurrences under problematic circumstances. In this study, a control strategy for energy storage elements (ESDs) which includes batteries and supercapacitors is proposed to enhance LVFRT under balanced and unbalanced faults. The MG comprises wind farms and/or photovoltaic arrays. Based on the dynamic simulations using MATLAB/SIMULINK, the ESDs can enhance LVFRT capability. A comparison of the conventional crowbar scheme and ESDs is realized, and the latter has a better performance than the former in retaining the DC-link voltage within satisfactory bounds. For the purpose of maintaining the DC-link voltage at a reference level, the battery stores extra power in the DC-bus of three systems. LVFRT is improved by the crowbar circuit, however the resistance consumes the extra power. Super capacitors (SCs) prevent DC voltage fluctuations, reduce active power oscillations, and hasten system stabilization when present. At an advanced stage of this effort, the coot bird optimizer (CBO) is applied to generate the best gains of bi-directional converter PI-controller and the ESDs ratings to have minimum ripples in the DC-bus voltage and to boost the LVFRT capability of the MGs. The viability of the proposed method based on the CBO’s results is indicated with further validations under different operating scenarios.

Beam displacement tolerances on a segmented mirror for higher-order Hermite–Gauss modes

Odd-indexed higher-order Hermite–Gauss (HG) modes are compatible with four-quadrant segmented mirrors due to their intensity nulls along the principal axes, which guarantees minimum beam intensity illuminating the bond lines between the segments thus leading to low power loss. However, a misplaced HG beam can cause extra power loss due to the bright intensity spots probing the bond lines. This paper analytically and numerically studies the beam displacement tolerances on a segmented mirror for the mode. We conclude that for ‘effective’ bond lines with 6 µm width, and the beam size chosen to guarantee 1 ppm clipping loss when centered, the beam can be rotated by roughly 1∘ or laterally displaced by 4% of its beam size while keeping the total power on the bond lines under 1 ppm. We also demonstrate that the constrained beam displacement parameter region that guarantees a given power loss limit, or the beam displacement tolerance, is inversely proportional to the bond line thickness.

Validating the association of Oxford classification and renal function deterioration among Taiwanese individuals with Immunoglobulin A nephropathy

Validation of the Oxford classification (MEST and MEST-C) for Immunoglobulin A nephropathy (IgAN) in the Taiwanese population is lacking. Our study aimed to validate this classification and assess individual lesion impact. We conducted a retrospective cohort study at Taichung Veterans General Hospital, Taiwan (Jan 2011–Jul 2023). Composite renal outcomes were evaluated using clinical conditions and estimated glomerular filtration rate (eGFR). We used Kaplan–Meier, univariable/multivariable logistic regression and ROC curves. Subgroup analysis considered eGFR < or ≥ 30.0 ml/min/1.73 m2. In 366 renal biopsies, serum creatinine was 1.34 mg/dl, eGFR 53.8 ml/min/1.73 m2, urine protein–creatinine ratio 1159 mg/g. T1/T2 lesions had lowest baseline eGFR (39.6/11.5 ml/min/1.73 m2), correlating with poorest renal survival (median survival 54.7/34.4 months). Univariable analysis linked all individual variables to worse renal outcomes. Multivariable analysis (MEST/MEST-C) showed only T1/T2 linked to worse outcomes. T score had highest predictive power (AUC 0.728, sensitivity 60.2%, specificity 83.6%), with MEST having high AUC (0.758). No extra predictive power was seen transitioning MEST to MEST-C. Subgroup analysis (eGFR < 30.0 ml/min/1.73 m2) associated C1 with improved renal outcomes (odds ratio 0.14, 95% CI 0.03–0.65). T lesion correlated with worse outcomes across subgroups. The T lesion consistently correlated with worse renal outcomes across all groups and baseline statuses. Integrating the C lesion into the transition from MEST to MEST-C did not enhance predictive power. Importantly, the C1 lesion was linked to improved renal outcomes in the eGFR < 30.0 ml/min/1.73 m2 subgroup, likely due to treatment effects.

Hybrid Energy Sources for Innovative Grid-Tied EV Charging Applications

Global power consumption is rising, making it vital to look for other sources of energy to solve the impending power crisis. Using grid-synchronized electric vehicles (EVs) is likely to be one way to do this. The whole power system is impacted when several EVs are paired with the grid, leading to imbalances in supply and demand as well as voltage and frequency. We have integrated solar and wind energy in this integration to reduce these concerns. One of the developments in smart grid technology that permits energy exchange between the EV and the grid is vehicle to grid (V2G) technology. The hybrid energy source proposed by this project is used to charge EVs. Here, power from the PV panel, wind turbine, and AC generator is used to charge the EV battery. Any excess energy is then used to fuel the linear and non-linear demands of the subsequent home. A proportional-integral (PI) controller, which is recognized for its dependability and independence from the real system model, is used to maximize the DC voltage extracted from the photovoltaic (PV) panel. The DC voltage is improved overall by the Boost converter’s improved DC output. Concurrently, the system incorporates an AC generator to supply extra power to the grid. A three-phase Voltage Source Inverter (VSI) converts an improved output of the Boost conversion process used to convert the electricity from the PV panel into AC power. In order to assure safe current injection into the grid, harmonic components detected in the VSI output are rectified using an LC filter to ensure grid compatibility. In this research, the voltage for the EV battery is adjusted using a bidirectional converter. Electricity from EVs that are not in use may be sent back into the grid for additional purposes. Simulink and MATLAB 2021a are used to simulate and evaluate the proposed method.