Output Line Research Articles

Research on MPPT control strategy based on CCAOA algorithm

ABSTRACT Photovoltaic arrays operating under partial shading conditions (PSCs) may exhibit multiple peaks in the power-voltage curve of the PV system output. The conventional maximum power point tracking (MPPT) algorithm cannot address the multipeak problem and demonstrates slow convergence speed, often falling into a local optimum. Consequently, this study proposes a collaborative and cosine arithmetic optimisation algorithm (CCAOA). First, a cosine factor is introduced into the mathematical optimisation. Circle chaotic mapping and cross-variance strategy were incorporated to boost the diversity and randomness within the algorithm population followed by a cooperative search strategy involving addition and subtraction to enhance the algorithm’s local search capability, thereby accelerating its convergence speed. We assessed the effectiveness of the CCAOA using six IEEE standard test functions. The CCAOA outperforms other algorithms in terms of convergence speed and accuracy. Furthermore, when applied to the MPPT control strategy, the CCAOA’s performance is validated through simulations and experiments. MPPT can be performed within approximately 0.3 to 0.4 s under static conditions, with 99.98% efficiency. Under dynamic conditions, only approximately 0.4 s is required for MPPT, thereby achieving a maximum efficiency of 99.99%. Conversely, the AOA, TSO, and PSO algorithms require over 0.4 s for MPPT and can be trapped in local optima under these two conditions. Experiments were conducted using a PV simulator and DC/DC converter, and the algorithm achieved efficiencies of 99.22%, 99.33%, and 99.54% under uniform irradiation and two PSCs, respectively.

Probing the effects of fiscal policy delays in macroeconomic IS–LM model

Probing the effects of fiscal policy delays in macroeconomic IS–LM model

Evaluation and Analysis of Cement Raw Meal Homogenization Characteristics Based on Simulated Equipment Models.

In recent years, the variability in the composition of cement raw materials has increasingly impacted the quality of cement products. However, there has been relatively little research on the homogenization effects of equipment in the cement production process. Existing studies mainly focus on the primary functions of equipment, such as the grinding efficiency of ball mills, the thermal decomposition in cyclone preheaters, and the thermal decomposition in rotary kilns. This study selected four typical pieces of equipment with significant homogenization functions for an in-depth investigation: ball mills, pneumatic homogenizing silos, cyclone preheaters, and rotary kilns. To assess the homogenization efficacy of each apparatus, scaled-down models of these devices were constructed and subjected to simulated experiments. To improve experimental efficiency and realistically simulate actual production conditions in a laboratory setting, this study used the uniformity of the electrical capacitance of mixed powders instead of compositional uniformity to analyze homogenization effects. The test material in the experiment consisted of a mixture of raw meal from a cement factory with a high dielectric constant and Fe3O4 powder. The parallel plate capacitance method was employed to ascertain the capacitance value of the mixed powder prior to and subsequent to treatment by each equipment model. The fluctuation of the input and output curves was analyzed, and the standard deviation (S), coefficient of variation (R), and homogenization multiplier (H) were calculated in order to evaluate the homogenization effect of each equipment model on the raw meal. The findings of the study indicated that the pneumatic homogenizer exhibited an exemplary homogenization effect, followed by the ball mill. For the ball mill, a higher proportion of small balls in the gradation can significantly enhance the homogenization effect without considering the grinding efficiency. The five-stage cyclone preheater also has a better homogenization effect, while the rotary kiln has a less significant homogenization effect on raw meal. Finally, the raw meal processed by each equipment model was used for clinker calcination and the preparation of cement mortar samples. After curing for three days, the compressive and flexural strengths of the samples were tested, thereby indirectly verifying the homogenization effect of each equipment model on the raw meal. This study helps to understand the homogenization process of raw materials by equipment in cement production and provides certain reference and data support for equipment selection, operation optimization, and quality control in the cement production process.

In‐plane ferroelectrics enabling reduced hysteresis in monolayer MoS2 transistors

AbstractTwo‐dimensional (2D) semiconductors, such as monolayer MoS2, has emerged as a profound material platform in the post‐Moore era due to their versatile applications for high‐performance transistors, memories, photodetectors, neuristors, and so on. Nevertheless, the inherent defects in these atomically thin materials have given rise to significant hysteresis in their field‐effect transistors (FETs), resulting in shifted threshold voltages and elevated power consumptions not only on single‐device levels but also at circuitry scales. We herein report that, by vertically integrating an in‐plane ferroelectric, NbOCl2, with monolayer MoS2 FETs, the hysteresis in both the output and transfer curves of the latter can be greatly suppressed, which we attribute to compensated electromigration currents by the polarization currents of the 2D ferroelectric. This work opens a new avenue to hysteresis‐free 2D transistors without necessitating defect‐free channels, thus allowing for their use in high driving‐voltage scenarios such as power electronics.

Reference equations for exhaled nitric oxide—what is needed?

Standardisation is the road to improvement! If we all measure exhaled nitric oxide (NO) the same way, we will be successful in having data to make reference questions. Many research groups have published their reference equation, but most differ considerably. About 25 years ago, using the flow of 50 ml s−1 was recommended and not using a nose clip. When collecting data worldwide, we still see publications that do not indicate what flow was used and that nose clip was utilised. Three things are needed: the analysing method, a flow recording and a filled-in nitric oxide questionnaire. The analysing method is because the techniques have different sensitivity, response times and calibration. The flow of 50 ml s−1 is on the steep part of the NO output curve; therefore, we need to record the flow to analyse repeated measurements or compare results. The NO questionnaire controls individual factors that may influence the NO measurements, i.e. food intake, smoking and upper airway infection. An important tool in following old and new disease treatments, at home or in health care, is exhaled biomarkers. If we follow the standardisation we have agreed upon, we will be able to have data to say what a high or a low exhaled NO value is.

Research on deep peaking cost allocation mechanism considering peaking demand subject and thermal power unit

The current peak-shaving auxiliary service cost allocation mechanism balances the revenue and expenditure of the power plant side, the peak-valley difference of the power grid is mainly caused by the peak-valley characteristics of the load and renewable energy. It is not reasonable that not reasonable the peak-shaving cost allocation mechanism does not consider user allocation. Therefore, this paper establishes a peak-shaving cost allocation mechanism that considers the peak-shaving demand subject, this article incorporates renewable energy power plants and loads into the peak-shaving demand subject. Firstly, this paper constructs an alternative scenario without peak-shaving demand through the mean line of load and available energy output and establishes an optimal scheduling model with deep peak-shaving and pumped storage power stations, this article takes the difference of system peak-shaving cost between two scenarios with and without peak-shaving demand as the marginal peak-shaving cost. Then, the Shapley value method in cooperative game is used to establish the peak-shaving cost allocation mechanism considering the main body of peak-shaving demand. In addition, It is used that the equal-kWh following load method constructed the equivalent output curve of renewable energy, following load method improves the existing allocation mechanism by comprehensive similarity. Finally, this paper analyzes and compares three different peaking cost allocation mechanisms. The example analysis shows that the peaking cost allocation mechanism considering peaking demand subjects. The example can reflect the peaking cost caused by different subjects and reduce the peaking pressure of thermal power units.

The Macroeconomic Policies of China and the United States in Dealing with Economic Shock Based on the IS-LM Model Taking the Financial Crisis in 2008 and the COVID-19 in 2020 as Examples

The Macroeconomic Policies of China and the United States in Dealing with Economic Shock Based on the IS-LM Model Taking the Financial Crisis in 2008 and the COVID-19 in 2020 as Examples

The effect of fragmentation risk on monetary conditions in the euro area

This paper measures the output effects of financial fragmentation in the euro area by estimating an extended IS curve. Using a panel approach, we find that two fragmentation measures are significantly related to the output gap: sovereign spreads and spreads in the long-term cost of borrowing of the private sector. We use these output effects to construct a Monetary Conditions Index (MCI) for euro area countries. This index summarizes the combined effect of the monetary policy stance and financial fragmentation. We show that the MCI approach is well-suited to capture cross-country differences in a fragmentation-enhanced measure of the monetary policy stance. Using this metric, we find that during the sovereign debt crisis, the cross-country dispersion of MCI's based on sovereign spreads was much larger than that based on the private cost of borrowing. We also show that convergence is slower for MCI's based on sovereign spreads. We conclude that the causes of fragmentation in monetary conditions may change over time, and that this has implications for the appropriate policy response.

Online modeling method for composite load model including EVs and battery storage based on measurement data

Load models have a significant influence on power system simulation. However, current load modeling approaches can hardly satisfy the diversity and time-varying characteristics of loads [including electric vehicles (EVs) and battery storage] in terms of model accuracy and computing efficiency. An online modeling method for composite load models based on measurement information is proposed in this paper. Firstly, the dominant factors in load model output are analyzed based on the active subspace of parameter space. Then the clustering algorithm is applied to cluster the large number of underlying loads based on the characteristics of load daily output curves. Finally, the underlying loads are equivalently aggregated from the low voltage levels to the high voltage levels to construct the composite load model. Simulation results obtained based on PSCAD/EMTDC demonstrate that the load model constructed by the proposed approach can accurately reflect the actual load characteristics of a power system.

Novel design of cryptographic architecture of nanorouter using quantum-dot cellular automata nanotechnology

The article introduces a revolutionary Nanorouter structure, which is a crucial component in the Nano communication regime. To complete the connection, many key properties of Nanorouters are investigated and merged. QCA circuits with better speed and reduced power dissipation aid in meeting internet standards. Cryptography based on QCA design methodologies is a novel concept in digital circuit design. Data security in nano-communication is crucial in data transmission and reception; hence, cryptographic approaches are necessary. The data entering the input line is encrypted by an encoder, and then sent to the designated output line, where it is decoded and transferred. The Nanorouter is offered as a data path selector, and the proposed study analyses the cell count of QCA and the circuit delay. In this manuscript, novel designs of (4:1)) Mux and (1:4) Demux designs are utilized to implement the proposed nanorouter design. The proposed (4:1) Mux design requires 3–5% fewer cell counts and 20–25% fewer area, and the propsoed (1:4) Demux designs require 75–80% fewer cell counts and 90–95% fewer area compared to their latest counterparts. The QCAPro utility is used to analyse the power consumption of several components that make up the router. QCADesigner 2.0.3 is used to validate the simulation results and output validity.

Multimode Emission in GaN Microdisk Lasers

AbstractQuantum well nanolasers usually show single‐mode lasing, as gain saturation suppresses emissions in other modes. In contrast, for whispering gallery mode microdisk lasers with GaN quantum wells as active material, above threshold multimode laser emission is observed. This intriguing emission feature is manifested in the fact that several modes simultaneously show the characteristic kink in the input–output curve at the onset of lasing. A quantum theory for nanolasers is used to support the experimental finding and to analyze this behavior in the presence of gain saturation. Coupling effects between neighboring modes are identified as the origin of multimode lasing, which initiate photon exchange between modes via population pulsations similar to classical wave‐mixing effects. A reduction of this type of mode coupling with increasing mode spacing is demonstrated. The results can pave the way for multimode application of nanolasers in integrated photonic circuits.

Allometric scaling of the parameters characterizing venous return surface in the generalized framework of circulatory equilibrium

Study objective: In the generalized framework of circulatory equilibrium (GCE), the integrated cardiac output (CO) curve characterizes the pumping abilities of the left and right hearts, whereas the venous return (VR) surface characterizes the preloading properties of the systemic and pulmonary circuits. Equilibrium CO (= VR), left (PLA) and right (PRA) atrial pressures are predicted from the intersection between the CO curve and VR surface. In VR surface, VR is theoretically related with stressed blood volume (V), PLA and PRA as: VR =V/W − Gs × PRA − Gp × PLA, where Gs and Gp is a ratio of systemic (Cs) and pulmonary (Cp) vascular compliance to W (time constant of the systemic and pulmonary circuits), respectively. However, there was a concern whether the standard parameters can be applicable to animals with different body size including human. The objective of this study is to experimentally investigate whether an allometric scaling of the parameters (Gs, Gp, W, Cs, Cp) of the VR surface is feasible. Hypothesis: Kleiber’s law indicates that an animal's metabolic rate scales to the 3⁄4 power of the animal's body weight (BW). Based on this, we hypothesize that Cs and Cp may be proportionate to BW, W may be proportionate to BW1/4. Hence, Gs and Gp may be proportionate to BW3/4. Methodology: Seven mongrel dogs (BW 26±2.8 kg) and 4 beagles (BW 9±0.5 kg) were anesthetized, and their left and right hearts were replaced by dual mechanical pumps. While V was kept constant, by controlling the speed of the fluid pumps, VR (ml/min), PLA and PRA (mmHg) were changed variably over a wide range to obtain six sets of VR, PLA and PRA. After the change of a known amount of V (4 mL/kg), six sets of VR, PLA and PRA were obtained in a similar manner. Using 12 sets of VR, PLA and PRA, we obtained Gs, Gp, W, Cs, and Cp using regression analysis in each animal. Finally, we analyzed relations between BW and all these parameters using regression analysis over the 11 animals. Data: Gs (r2=0.73, p value for independent variable piv<0.01; p value for intercept, pi=0.57) and Gp (r2=0.81, piv<0.01, pi=0.64) were proportionate to BW3/4. Cs (r2=0.37, piv=0.027, pi=0.40) and Cp (r2=0.61, piv<0.01, pi=0.48) were proportionate to BW. However, W (r2=-0.11, piv=0.90, pi=0.17) was not associated with BW1/4. Summary of results: All parameters characterizing VR surface except for W were significantly associated with BW. W did not show a significant association with BW, potentially due to the low variations of BW. Conclusions: Allometric scaling of VR surface may be feasible and effective in future clinical application of GCE. NTT Research, Inc. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Simulation of the 2E Technique on neutron multiplicity measurement as a function of fragment mass in spontaneous fission of 252Cf

A Monte Carlo simulation algorithm to investigate the measurement of the average prompt neutron multiplicity as a function of pre-neutron mass, ν(A), for fragments from the spontaneous fission of 252Cf is presented. The input data consist of experimental measurements of the kinetic energy and mass distributions obtained by Göök et al., and the values of ν(A) calculated using the FIFRELIN model by Piau et al., νth(A). We analyze the output curve, νsim(A), obtained by simulation of the 2E technique, which should ideally match νth(A). However, we find that νsim(A) exhibits a maximum value at A≈122, close to mass symmetry, while νth(A) has a maximum at A≈118. Additionally, we observe that νsim(A) > νth(A) for A< 90 and A> 169, respectively. We attribute this discrepancy to inaccuracies in the relationship between provisional mass and the pre-neutron mass used in the 2E technique for data processing in each fission event.

Reduced partial shading effect and enhancement of performance metrics using a Fibonacci based algorithm

AbstractPartial shading within arrays diminishes power output, induces hotspots, and compromises module integrity, thereby impacting system performance. The presence of bypass diodes further exacerbates these issues by introducing non‐convexities in power curves, leading to additional power losses. To solve this problem, a new reconfiguration technique named Fibonacci Random Number Generator is proposed in this work which minimizes the effects of shading on the panels. The proposed methodology swiftly reduces current discrepancies between PV array rows by reshuffles the panels in an array to disperse the shade better using a mathematical formula resulting in increased power output and smoother power curves during partial shading events. The effectiveness of the proposed method is measured in terms of GMPP, row current calculations, power loss (PL), mismatch losses (ML), execution ratio (ER), fill factor (FF), and capacity factor (CF) for four distinctive shading conditions. Validation of results in software and hardware platforms showcase the applicability of proposed approach in real‐time environments. Results indicate significant average power improvements of 25.49%, 15.47%, and 9.29% compared to existing popular reconfigurations like Skyscraper, Ken‐Ken, and Chaotic baker map. The proposed method stands out as a potent tool for optimizing PV arrays within real‐world systems grappling with partial shading issues.

Optimal configuration of distributed energy storage considering intending island recovery in faulty distribution networks

With the rapid development of distributed generation, represented by photovoltaic power, the access of a large number of distributed generation poses threats to the security and reliable operation of islanded distribution networks. However, relying on the distributed energy storage system can stabilize the island power supply, which can effectively improve the reliability of the island distribution network. To this end, under the premise of knowing photovoltaic output and load forecast curve, this paper proposes a distributed energy storage optimization configuration method in the active islanding operation mode of multi-source distribution network, which satisfies the “N-1″ safety criterion. First, this paper establishes an optimization configuration model for distributed energy storage with multiple objectives, including minimizing the load shedding in the non-fault loss of power zone, the initial investment cost of distributed energy storage, the node voltage deviation and the system frequency offset. Then, aiming at the islanded power flow calculation process mentioned above, an improved trust region algorithm is proposed, and integrating this method with the harmony search algorithm and ”N-1″ safety criterion solves the model. Finally, the IEEE 33-node distribution system is used to test the performance of the proposed algorithm. The results show that the proposed improved trust region algorithm has the advantages of fast convergence speed and short time-consumption compared with the traditional trust region algorithm. And the proposed optimization configuration scheme for distributed energy storage can satisfy the “N-1″ safety criterion of the distribution network under different fault scenarios.

Impedance spectroscopy analysis of thermoelectric modules under actual energy harvesting operating conditions and a small temperature difference

Thermoelectric (TE) devices can convert heat into electricity and have gained great interest as energy harvesters in many applications, such as self-powered sensors, solar TE generators and industrial waste heat recovery. Not many techniques are usually available for their characterization under operating conditions. Consequently, only current-voltage (power output) curves are typically reported to account for their performance, which provide limited information. Impedance spectroscopy, which has been mainly applied to the study of TE modules suspended in air or vacuum, has the advantage to be used under operating conditions. Here, we exploit this advantage and provide an in-depth analysis of the impedance response of standard TE devices when they operate under a small temperature difference. First, we derive the physical models (equivalent circuits) for the two most common operating conditions: (i) constant temperature difference and (ii) constant heat power input. Then, we use the obtained equivalent circuit to successfully fit experimental impedance measurements in both operating modes, which show significant differences. From the fittings, it is possible to obtain the thermal contact resistance between the TE device and the heat exchangers (heat source and heat sink) among other key parameters. In addition, we analyze the variations found in the impedance spectra for different current output levels. Moreover, we show how different electrical resistances, extracted from the impedance results, directly relate to the slope of the I-V curve (power output), and can provide very valuable information about the different processes that determine its value. All these results establish impedance spectroscopy as a very powerful tool to characterize TE devices under operating conditions and as a method that can provide highly valuable insights into their performance.

Design of a charge-sensitive amplifier for MEMS piezoelectric hydrophone

Hydrophone is an important part of sonar system and convert acoustic signal into electrical signal. However, the electrical signal generated by the hydrophone is relatively weak and cannot be directly used for underwater detection and communication. Therefore, it is necessary to preprocess the generated electrical signal. In this paper, a switched capacitor charge-sensitive amplifier for MEMS piezoelectric hydrophone is designed. In the structure, two single-channel charge amplifiers are used for time-division multiplexing. The noise sampling and charge amplification are performed separately in the same half cycle to achieve the effect of alternating output, thereby increasing the sampling rate and solving the problem of discontinuous output of the switched capacitor circuit. In the circuit design, virtual switch and two-phase non-overlapping clock are adopted to reduce the error caused by charge injection and clock feedthrough effect of CMOS switch. What’s more, the correlated double sampling technique is used to reduce the offset and low frequency noise of the circuit. The gain of the charge-sensitive amplifier designed in this study is 26 dB, the bandwidth is 0.8Hz∼17.6kHz, the equivalent input noise power spectral density is 115.6 nV/Hz at 0.1Hz, and the charge sensitivity is 2 mV / pC. The fitting line between the input charge and the amplitude of the output curve is similar to the theory. The simulation results show that the charge-sensitive amplifier proposed in this study meets the design requirements of the MEMS piezoelectric hydrophone readout circuit.

Magnetic Design and Electromagnetic Field Simulation of Downhole Turbine Generator

With the increasing difficulty of oil and gas resources exploration and the increase of drilling operations in complex geological environments, the challenges faced by oil drilling operations are also increasing. With the continuous improvement of the intelligence of MWD/LWD drilling technology and downhole instruments, the demand for electric energy is also increasing. In order to ensure the normal operation of the equipment and the accurate acquisition of data, this paper designs a new type of external rotor downhole turbine generator, and designs the structure and parameters of the turbine generator. Finally, Ansoft Maxwell software is used to simulate and analyze the electromagnetic field of the generator. The results show that the induced electromotive force and load current waveform obtained by electromagnetic field simulation analysis have good sinusoidality. At the rated speed of 2500rpm, the effective value of the output line voltage of the turbine generator is about 49.1V, the effective value of the line current is about 10.99A, and the output power is about 841.17W, which meets the design requirements. The research has certain guiding significance for practical engineering.

Research on Coordinated Optimization of Source-Load-Storage Considering Renewable Energy and Load Similarity

Currently, the global energy revolution in the direction of green and low-carbon technologies is flourishing. The large-scale integration of renewable energy into the grid has led to significant fluctuations in the net load of the power system. To meet the energy balance requirements of the power system, the pressure on conventional power generation units to adjust and regulate has increased. The efficient utilization of the regulation capability of controllable industrial loads and energy storage can achieve the similarity between renewable energy curves and load curves, thereby reducing the peak-to-valley difference and volatility of the net load. This approach also decreases the adjustment pressure on conventional generating units. Therefore, this paper proposes a two-stage optimization scheduling strategy considering the similarity between renewable energy and load, including energy storage and industrial load participation. The combination of the Euclidean distance, which measures the similarity between the magnitude of renewable energy–load curves, and the load tracking coefficient, which measures the similarity in curve shape, is used to measure the similarity between renewable energy and load profiles. This measurement method is introduced into the source-load-storage optimal scheduling to establish a two-stage optimization model. In the first stage, the model is set up to maximize the similarity between renewable energy and the load profile and minimize the cost of energy storage and industrial load regulation to obtain the desired load curve and new energy output curve. In the second stage, the model is set up to minimize the overall operation cost by considering the costs associated with abandoning the new energy sources and shedding loads to optimize the output of conventional generator sets. Through a case analysis, it is verified that the proposed scheduling strategy can achieve the tracking of the load curve to the new energy curve, reducing the peak-to-valley difference of the net load curve by 48.52% and the fluctuation by 67.54% compared to the original curve. These improvements effectively enhance the net load curve and reduce the difficulty in regulating conventional power generation units. Furthermore, the strategy achieves the full discard of renewable energy and reduces the system operating costs by 4.19%, effectively promoting the discard of renewable energy and reducing the system operating costs.

Feature Extraction Approach for Distributed Wind Power Generation Based on Power System Flexibility Planning Analysis

This study addresses the integral role of typical wind power generation curves in the analysis of power system flexibility planning. A novel method is introduced for extracting these curves, integrating an enhanced K-means clustering algorithm with advanced optimization techniques. The process commences with thorough data cleaning, filtering, and smoothing. Subsequently, the refined K-means algorithm, augmented by the Pearson correlation coefficient and a greedy algorithm, clusters the wind power curves. The optimal number of clusters is ascertained through the silhouette coefficient. The final stage employs particle swarm and whale optimization algorithms for the extraction of quintessential wind power output curves, essential for flexibility planning in power systems. This methodology is validated through a case study involving wind power output data from a new energy-rich provincial power grid in North China, spanning from 1 January 2019, to 31 December 2022. The resultant curves proficiently mirror wind power fluctuations, thereby laying a foundational framework for power system flexibility planning analysis.