Power Output Values Research Articles

Analisis Prestasi Penuai Tenaga Mikro Frekuensi Radio Berkuasa Rendah Menggunakan Antena MEMS Bagi Rangkaian Sensor Tanpa Wayar

Recently, there has been a growing tendency of interest from researchers to use ambient energy to power electronic equipment using various energy harvesting techniques. Micro energy harvesting is a potential technique to convert ambient energy from the environment to electrical energy. The wireless sensor network requires a constant source of electrical energy to activate it and the radio frequency (RF) ambient energy source that always exists in the environment is very suitable for use. Therefore, the designed and developed RF micro energy harvester consisting of an impedance matching circuit, a voltage multiplier and a rectifier circuit does not require an external energy source to activate it. This RF micro energy harvester circuit is constructed and simulated using PSPICE software by connecting a 1 MΩ load resistor. At an input power of -20 dBm or 10 μW captured by the MEMS antenna, the values of the output voltage and current produced in this energy harvester circuit are 2.36 V and 1.7 mA, respectively. Meanwhile, the maximum efficiency percentage of the entire RF micro energy harvester circuit is 55.7%. The output power value of 40.12 mW is higher than the input power value of 10 μW. This RF micro energy harvester is capable of activating a wireless sensor network with a minimum input current requirement of 1 mA. An integrated circuit layout using 180 nm CMOS technology for a multiplier circuit has been successfully developed with a very small size of 22.48 x 56.96 μm2 as proof that the circuit can be fabricated as an integrated circuit chip.

Design of Bi2Te3-based thermoelectric generator in a widely applicable system

A Bi2Te3-based thermoelectric generator (TEG) system cooled by heat radiation fin (HRF) applies to most scenarios of low-temperature power generation and waste heat recovery, while the high performance of the TEG system requires the precise design of the structure. Here we developed a theoretical model to simulate the thermal-electric coupling of the TEG system and analyzed the Bi2Te3-based TEG system with the aid of numerical and experimental methods. Results show that the increase in height of TEG not only improves the conversion efficiency but leads to a peak value of output power, which is much different from the traditional view that the output power solely decreases with the increase of height of TEG. Compared to the thickness of the fin, the height of the fin plays an essential role in optimizing the performance of TEG. By adding an electrical fan to improve the heat exchange coefficient, the net output power is doubled and the net conversion efficiency is improved by more than 80%. Besides, the structure of the TEG system is designed for different material parameters via the theoretical method. We anticipate that our results will guide the design and optimization of the TEG system.

Orthogonally Polarized Dual-Wavelength Gain-Switched Ho:LuLiF4 Pulse Laser

A compact, orthogonally polarized, gain-switched a-cut Ho:LuLiF4 laser with intra-cavity pumping by a self-Q-switched Tm:YAP laser is demonstrated here for the first time. The π-polarization laser at 2052 nm and σ-polarization laser at 2066 nm were experimentally observed with the maximum output power values of 299 mW and 126 mW, respectively, and the two polarization directions were always kept mutually orthogonal as the pump power increased. The ratio of the output power between the two orthogonal polarization lasers was nearly 1:1 at a pump power of 18.4 W. The minimum pulse width of the Ho:LLF laser was 326 ns, the maximum repetition rate was 24 kHz, and the maximum average energy was 28 μJ.

Highly efficient operation and uniform characteristics of curved mirror vertical-cavity surface-emitting lasers

This study obtained highly uniform and efficient GaN-based vertical-cavity surface-emitting lasers with curved mirrors from a single wafer. The average threshold current (I th) and the optical output power (P max) of 14 chips measured up to 7.0 mA were 0.64 mA and 4.5 mW, respectively. The standard deviations of I th and P max were 6.7% and 5.1%, respectively. Additionally, the best chip showed maximum values of wall plug efficiency and output power of 13.4% and 7.6 mW, respectively, at 5.2 mA and 12.8 mA operating currents.

About theory of hybride TWTO and an amplifire with a complex permittivity

The purpose of this work is to construct a nonlinear theory of a hybrid between travelling wave tube (TWT) and an amplifier with a complex permittivity. Methods. The following model is considered: an ion-compensated one-dimensional electron beam penetrates the input travelling wave tube section, then flies into a medium with a complex permittivity, and then enters the output travelling wave tube section. A linear theory of this hybrid is constructed, and its results are compared with the results of the well-known linear theory of travelling wave tube. A nonlinear theory of this hybrid was constructed by a modified wave method, and the results were compared with the nonlinear travelling wave tube theory obtained by the classical Ovcharov–Solntsev’s wave method. In addition, to test the limits of applicability of the obtained results, a stationary nonlinear theory of the hybrid was constructed, obtained using the large particle method. The results of this theory were also compared with the stationary nonlinear travelling wave tube theory constructed using the large particle method. Results and conclusion. Based on the results of the developed theories, it is shown that, under certain parameters, the linear theory and nonlinear theories (both by the modified Ovcharov–Solntsev’s wave method and by the large particle method) make it possible to obtain comparable results both in the case of a classical travelling wave tube and for the hybrid under study. It is shown that under certain parameters, due to the resistive instability, the bunching of electrons can be noticeably improved and, as a result, the gain of the hybrid can exceed the gain in a classical travelling wave tube with the same parameters and the same total length of the device in the linear mode of operation. In the nonlinear mode of operation, the specified hybrid, with optimal environmental parameters, can have significantly higher values of output power and efficiency than travelling wave tube with the same value of the space charge parameter and the Pierce parameter.

Wind power resources potential for energy supply of isolated regions of Kamchatska

The paper presents the potential of the wind resources for energy supply in the Kamchatka Territory. This region is isolated from the United Energy System of Russia and has a large number of remote settlements. The possibility of using wind energy resources in the region to replace diesel power plants and to reduce CO2 emissions are assessed. Estimates of the average power output values of the wind turbine Enercon E-53 810 kW, on the basis of hourly data on wind resources over a 10-year period (2011-2020) and the share of consumer load coverage for 11 settlements in the region are calculated. Territorial distribution of the specific power generation potential for this wind turbine model is presented with the use of GIS technologies. Daily and seasonal variations in productivity and share of load coverage, as well as the territorial distribution of these characteristics of the energy supply potential by the use of wind resources, are determined.

Laser system of cold atom optical clock in China Space Station

The world's first space optical clock (SOC) developed in China, which is composed of five subsystems, i.e. an optical unit, a physics unit, an electronic control unit, a space optical frequency comb, and an ultrastable laser, was successfully launched with the Mengtian space laboratory on October 31, 2022, and entered into the China Space Station (CSS). Compact and stable laser is a key element for the operation of the SOC. The optical unit consists of 5 lasers with wavelengths of 461, 679, 689, 707 and 813 nm, respectively. With a synchronous-tuning-like scheme, high-quality external cavity diode lasers (ECDLs) are developed as the seeds. The linewidths of the lasers are all reduced to approximately 100 kHz, and their tuning ranges, free from mode hopping, are capable of reaching 20 GHz, satisfying the requirements for the SOC. With careful mechanical and thermal design, the stability of the laser against vibration and temperature fluctuation is sufficiently promoted to confront the challenge of rocket launching. While the power from the ECDL is sufficient for 679-nm repump laser and 707-nm repump laser, additional injection lock is utilized for the 461-nm laser and 689-nm laser to amplify the power of the seeds to more than 600 mW, so that effective first and second stage Doppler cooling can be achieved. To generate an optical lattice with deep enough potential well, over 800-mW 813-nm lasers are required. Therefore, a semiconductor tapered amplifier is adopted to amplify the seed to more than 2 W, so as to cope with various losses of the coupling optics. The wavelengths and output power values of the 5 lasers are monitored and feedback is controlled by the electronic control unit. All the modules are designed and prepared as orbital replaceable units, which can be easily replaced by astronauts in case failure occurs. Now the lasers are all turned on and operate normally in CSS. More data of the SOC will be obtained in the near future. At present stage, according to our evaluation, the continuous operation time of the SOC is limited by the injection locked lasers, which are relatively vulnerable to mode hopping. Hopefully, this problem can be solved by improving the laser diode preparing technology, or developing fiber lasers with compact frequency conversion modules.

Modified Virtual Impedance Control to Improve Real and Reactive Power Output in Islanded Microgrid

In this paper, modified virtual impedance control technique is proposed to bring back the sum of real power and reactive power output of all the distributed generators (DGs) to the nominal value. The value of real and reactive power output falls down in the conventional virtual impedance control technique for reactive power sharing improvement in islanded microgrid. The proposed technique modifies the d-axis component of virtual impedance voltage which in turns brings back the sum of real and reactive power output of distributed generators to nominal value keeping achieved reactive power sharing and output voltage intact. The impact of modified virtual impedance technique on the stability of the system is also investigated using eigenvalue analysis. No communication link or optimization technique is required in this work which reduces the complexity of the system making it more reliable and easier to design. The proposed technique works satisfactory for local load as well as the loads which are connected distantly from the distributed generators. The feasibility of the proposed technique is validated in time domain simulation in MATLAB/Simulink. The MATLAB R2020b version 9.9 is used in this research work.

Development of Neural Network Prediction Models for the Energy Producibility of a Parabolic Dish: A Comparison with the Analytical Approach

Solar energy is one of the most widely exploited renewable/sustainable resources for electricity generation, with photovoltaic and concentrating solar power technologies at the forefront of research. This study focuses on the development of a neural network prediction model aimed at assessing the energy producibility of dish–Stirling systems, testing the methodology and offering a useful tool to support the design and sizing phases of the system at different installation sites. Employing the open-source platform TensorFlow, two different classes of feedforward neural networks were developed and validated (multilayer perceptron and radial basis function). The absolute novelty of this approach is the use of real data for the training phase and not predictions coming from another analytical/numerical model. Several neural networks were investigated by varying the level of depth, the number of neurons, and the computing resources involved for two different sets of input variables. The best of all the tested neural networks resulted in a coefficient of determination of 0.98 by comparing the predicted electrical output power values with those measured experimentally. The results confirmed the high reliability of the neural models, and the use of only open-source IT tools guarantees maximum transparency and replicability of the models.

Quantitative Analysis of Solar Photovoltaic Panel Performance with Size-Varied Dust Pollutants Deposition Using Different Machine Learning Approaches.

In this paper, the impact of dust deposition on solar photovoltaic (PV) panels was examined, using experimental and machine learning (ML) approaches for different sizes of dust pollutants. The experimental investigation was performed using five different sizes of dust pollutants with a deposition density of 33.48 g/m2 on the panel surface. It has been noted that the zero-resistance current of the PV panel is reduced by up to 49.01% due to the presence of small-size particles and 15.68% for large-size (ranging from 600 µ to 850 µ). In addition, a significant reduction of nearly 40% in sunlight penetration into the PV panel surface was observed due to the deposition of a smaller size of dust pollutants compared to the larger size. Subsequently, different ML regression models, namely support vector machine (SVMR), multiple linear (MLR) and Gaussian (GR), were considered and compared to predict the output power of solar PV panels under the varied size of dust deposition. The outcomes of the ML approach showed that the SVMR algorithms provide optimal performance with MAE, MSE and R2 values of 0.1589, 0.0328 and 0.9919, respectively; while GR had the worst performance. The predicted output power values are in good agreement with the experimental values, showing that the proposed ML approaches are suitable for predicting the output power in any harsh and dusty environment.

Theoretical modelling and experimental investigation on a frequency up-converted nonlinear piezoelectric energy harvester

Ambient vibration energy harvesting has attracted the great attention of numerous researchers to replace the battery power supply strategy of electronic devices. However, the high natural frequency and narrow broadband operation are still significant shortcomings of the conventional vibration energy harvesters to be widely deployed. This paper presents a novel piezoelectric energy harvester (PEH) based on the traditional impact frequency up-converted PEH to achieve lower and broader operating frequency. Nonlinear magnetic force is adopted to regulate the working frequency of PEH. Distributed-parameter modelling and magnetic force simplified modelling are applied in analyzing the piecewise linear dynamic characteristics of the low-frequency driving beam, and the piezoelectric effect is employed for calculating the output voltage of the high-frequency generating beams. Theoretical results comparison between the traditional impact PEH and the proposed novel PEH shows that the introduced nonlinear magnetic force offers a lower initial frequency and broader operating bandwidth. The comparison experimental study achieves a close match to the theoretical results. Under excitation conditions of 3 m/s 2 excitation acceleration, 3 mm impact distance, and 19 mm magnet distance, the initial frequency decreases by about 9.5 Hz, and the operating bandwidth increases from 9 Hz to 16.5 Hz. The maximum power output value of the proposed PEH is 0.491 mW. The novel proposed PEH in this paper provides promising guidance and understanding for energy harvesting in low and broadband environmental vibration. • A novel frequency up-converted nonlinear piezoelectric energy harvester (PEH) is proposed for lower and wider bandwidth energy harvesting. • Developed the theoretical model and analyzed the performance of the device based on averaging method. • The comparison experimental results achieve a close match to the theoretical research that the novel PEH has lower and wider operating frequency than the conventional impact PEH.

Design and Implementation MPPT-CPG for Constant Power Battery Charger

The power produced by photovoltaic is very dependent on irradiation conditions and temperature so that the power can be low or high. The load cannot work if the power is low, but it harms the load if the power is too high. Two modes are used for this system, they are MPPT and CPG mode. When PV power is less than limit power (Plimit), then it works on MPPT mode. The MPPT finds maximum power, then if PV power reaches Plimit or more, it works on CPG mode. During CPG mode, SEPIC converter output power is maintained constant at Plimit so the battery can be charged using the Constant Power Method. The Algorithm used for each mode is the variable Step Size Climbing. The Variable Step Size Hill-Climbing on MPPT performs maximum power according to irradiation conditions. Variables Step Size Hill-Climbing on CPG stabilizes the output power value of SEPIC being constant to charge the battery using the power constant method by keeping the power as constant as its limit power, voltage and current electricity bring into line with charge conditions. The results of the hardware integrated test for MPPT-CPG, the Variable Step Size Hill Climbing algorithm can search for the maximum power point (MPP) generated by PV and can produce an output power of 27.97 W in average.

Association of Gene Variants for Mechanical and Metabolic Muscle Quality with Cardiorespiratory and Muscular Variables Related to Performance in Skiing Athletes.

Background: Skiing is a popular outdoor sport posing different requirements on musculoskeletal and cardiorespiratory function to excel in competition. The extent to which genotypic features contribute to the development of performance with years of ski-specific training remains to be elucidated. We therefore tested whether prominent polymorphisms in genes for angiotensin converting enzyme (ACE-I/D, rs1799752), tenascin-C (TNC, rs2104772), actinin-3 (ACTN3, rs1815739) and PTK2 (rs7460 and rs7843014) are associated with the differentiation of cellular hallmarks of muscle metabolism and contraction in high level skiers. Material & Methods: Forty-three skiers of a world-leading national ski team performed exhaustive cardiopulmonary exercise testing as well as isokinetic strength testing for single contractions, whereby 230 cardiopulmonary measurements were performed in the period from 2015–2018. A total of 168 and 62 data measurements were from the Alpine and Nordic skiing squads, respectively. Ninety-five and one hundred thirty-five measurements, respectively, were from male and female athletes. The average (±SD) age was 21.5 ± 3.0 years, height 174.0 ± 8.7 cm, and weight 71.0 ± 10.9 kg for the analysed skiers. Furthermore, all skiers were analysed concerning their genotype ACE-I/D, Tenascin C, ACTN3, PTK2. Results: The genotype distribution deviated from Hardy–Weinberg equilibrium for the ACTN3 genotype, where rs1815739-TT genotypes (corresponding to the nonsense mutation) were overrepresented in world-class skiers, indicating a slow muscle fibre phenotype. Furthermore, the heterozygous rs2104772-AT genotypes of TNC also demonstrated the best scaled peak power output values during ramp exercise to exhaustion. The highest values under maximum performance for heart rate were associated with the rs1799752-II and rs1815739-CC genotypes. The lowest values for peak power of single contractions were achieved for rs1815739-CC, rs1799752-II and rs7843014-CT genotypes. The skiing discipline demonstrated a main influence on cardiorespiratory parameters but did not further interact with genotype-associated variability in performance. Discussion: Classically, it is pointed out that muscles of, for example, alpine skiers do not possess a distinct fibre type composition, but that skiers tend to have a preponderance of slow-twitch fibres. Consequently, our findings of an overrepresentation of ACTN3-TT genotypes in a highly selective sample of elite world class skiers support the potential superiority of a slow fibre type distribution. Conclusions: We suggest that one competitive advantage that results from a slow, typically fatigue-resistant fibre type distribution might be that performance during intense training days is better preserved, whereby simply a higher technical training volume can be performed, yielding to a competitive advantage.

Systematic error compensation for improving accuracy of the electrosurgical unit.

This paper presents an approach to systematic error correction for improving the accuracy of the electrosurgical unit (ESU), through a method that enables safer operation for both surgeons and patients. The equations for systematic errors encountered during the calibration of the eight ESUs were obtained using regression analysis. The ESU calibration was performed using a power analyzer and the reference power value was selected on the ESU panel; the power value indicated by the ESU was noted from the power analyzer and recorded. The fitted regression models were suitable for predicting systematic errors associated with ESU output power values, as a reduction of about 84 % was noted in cutting power (CuP) and about 74 % for coagulation power (CoP). After correction, systematic error values remained below 1.9 W and 0.4 W in cutting and coagulation power, respectively. The maximum error values obtained were less than those specified for the IEC 60601-2-2 standard for all evaluated ESUs.

Jumping mechanism in the marsh beetles (Coleoptera: Scirtidae)

The jumping mechanism with supporting morphology and kinematics is described in the marsh beetle Scirtes hemisphaericus (Coleoptera: Scirtidae). In marsh beetles, the jump is performed by the hind legs by the rapid extension of the hind tibia. The kinematic parameters of the jump are: 139–1536 m s−2 (acceleration), 0.4–1.9 m s−1 (velocity), 2.7–8.4 ms (time to take-off), 0.2–5.4 × 10–6 J (kinetic energy) and 14–156 (g-force). The power output of a jumping leg during the jumping movement is 3.5 × 103 to 9.6 × 103 W kg−1. A resilin-bearing elastic extensor ligament is considered to be the structure that accumulates the elastic strain energy. The functional model of the jumping involving an active latching mechanism is proposed. The latching mechanism is represented by the conical projection of the tibial flexor sclerite inserted into the corresponding socket of the tibial base. Unlocking is triggered by the contraction of flexor muscle pulling the tibial flexor sclerite backwards which in turn comes out of the socket. According to the kinematic parameters, the time of full extension of the hind tibia, and the value of the jumping leg power output, this jumping mechanism is supposed to be latch-mediated spring actuation using the contribution of elastically stored strain energy.

Experimental Investigation and Performance Characteristics of Francis Turbine with Different Guide Vane Openings in Hydro Distributed Generation Power Plants

This article presents a study on the performance characteristics of a Francis turbine operating with various guide vane openings to determine the best operating point based on unit quantities. The guide vane openings were specified based on the width between the vanes at their exit, i.e., 10 mm, 13 mm, 16 mm, and 19 mm. The performance characteristic curves of the Francis turbine—head versus speed, torque versus speed, discharge versus speed, and efficiency versus speed—were obtained at various input power and guide vane openings. From these data, unit curves were plotted and the corresponding best efficiency points were obtained. The highest efficiency of 50.25% was obtained at a guide vane opening of 19 mm. The values of head, discharge, speed, and output power at BEP were 7.84 m, 13.55 lps, 1250 rpm, and 524 W, respectively.

Induction Motor Torque Measurement using Prony Brake System and Close-loop Speed Control

Three-phase induction motors are the main drivers of the industrial world because of their low price and good reliability. However, this type of motor does not have built-in speed control. These problems can be overcome by utilizing the Variable Frequency Drive (VFD) inverter. This research investigates the induction motor's characteristics in every load condition and combines a VFD inverter with an external speed controller based on Arduino. The motor is mounted on a Prony brake testbed frame to measure the motor's torque and mechanical power. The test results show the highest torque value obtained is 0.57 Nm, and the highest output power value is 0.042 kW. The motor cannot maintain the setpoint speed after loading in the open-loop control system. Meanwhile, the closed-loop control system has been successfully implemented, and the motor can return the speed to the setpoint value after loading, with an average settling time of 14.67 seconds.

Improved Frequency Control Strategy for Offshore Wind Farm Integration via VSC-HVDC

Voltage source converter based high voltage DC system (VSC-HVDC) has become a very promising solution to integrate offshore wind farm. However, the equivalent inertia of the modern power system with large renewable energy integration becomes small, which will arouse some frequency stability problems. To tackle this problem, this paper proposes an improved frequency regulation strategy for VSC-HVDC integrated offshore wind farm. Firstly, in the frequency decrease stage, the rotor kinetic energy of wind turbines (WTs) is used to suppress the decrease of the frequency, and the control parameters are determined to make full use of the mechanical power and rotor kinetic energy of WTs, the frequency nadir is improved. Secondly, in the rotor speed recovery stage, the DC capacitors of VSC-HVDC are used to release power to compensate the deficiency value of wind farm output power and avoid the secondary frequency drop (SFD) problem. Lastly, the simulation is conducted in PSCAD/EMTDC to validate the effectiveness of the proposed coordinated frequency control strategy.

Two implementations of 120 GHz transformer cross‐coupled oscillator based on cascode structure in 55 nm CMOS technology

AbstractTwo oscillators are designed and fabricated, focusing on the output power and tuning range in the terahertz band. The first one is a transformer cross‐coupled oscillator based on the cascode structure, and the second one is a self‐mixing transformer cross‐coupled oscillator. Higher output power is obtained by using transformer coupling instead of direct or capacitive coupling. Using the frequency mixing principle, a wider tuning range is obtained. Both chips are processed by 55 nm CMOS technology. The measured frequency tuning range is 115.9–129.1 and 110.8–128.0 GHz, respectively. The measured peak value of output power is 3.2 and −14.3 dBm, respectively.

A novel probabilistic power curve model to predict the power production and its uncertainty for a wind farm over complex terrain

This study proposes a novel probabilistic power curve model for wind turbine and combines it with a hybrid wind farm model to quantify the accuracy and uncertainty of power prediction of wind farm over complex terrain with low computational cost. The proposed probabilistic power curve model for an active stall-regulated turbine is expressed by the beta distribution to estimate the uncertainty of power output at a certain wind speed. The predicted mean value and standard deviation of power output by the proposed model show favorable agreement with the measurement, while the conventional deterministic model cannot estimate the uncertainty of power output from wind turbines at all. The hybrid wind farm flow model is then presented, in which the effects of local terrain and surface roughness on the wind speed, wind direction and turbulence intensity are taken into account by the CFD simulation, and the wind turbine wakes are represented by an advanced wake model. The predicted wind speed and turbulence intensity show good agreement with those measured in a wind farm over complex terrain in the north of Japan. Finally, the proposed probabilistic power curve model is combined with the hybrid farm flow model to estimate the mean value and standard deviation of wind farm power production and is validated by the field measurement. The weighted mean absolute percentage error in mean value is reduced from 18.1% to 7.2% with consideration of wake effects and that in standard deviation is reduced from 100% to 15.6% by using the proposed probabilistic power curve model.