Load Matching Research Articles

Using thermal load matching strategy to locate historical benchmark data for moving-window PCA based fault detection in air handling units

Principal component analysis (PCA) methods have been reported to successfully detect some faults. Unfortunately, for the actual systems, there are few literatures on how to retrieve the historical fault-free operating information as training data which is the benchmark to characterize system performance. This study proposes a dynamic thermal load matching strategy to locate historical candidate information based on mass and thermal balance. Seven parameters related to thermal load are deduced to replace some variables such as solar flux, heat gain, and heat dissipation which are usually unavailable in most real systems. Combining with the moving-window PCA fault detection method, the strategy is validated to detect the fault symptom in 52 fault-free and 54 fault days of air conditioning systems from ASHRAE 1312-RP. The data sizes of a time-series data window, moving speed, and historical candidate pool, are defined as 60, 10 and 900 data points, respectively. The detection results of fault symptom show that the proposed strategy exhibits higher percentages of fault symptom than those reported in the published literatures. On the other hand, the fault detection effects highly depend on the severity level of fault symptom, but present slightly tiny negative correlation with PCA similarity factors.

Techno-economic analysis of the transition towards the large-scale hybrid wind-tidal supported coastal zero-energy communities

In the current academic fields of zero-energy community, there is still limited knowledge on the integration of a coastal community with hybrid ocean-related energy systems. This study investigates the feasibility of a coastal community to reach zero-energy with the support of a hybrid offshore wind and tidal stream energy generation system, as well as an ocean and solar thermal energy supported district cooling and heating system. TRNSYS simulation was performed to demonstrate a proposed community that comprises 8 high-rise residential buildings and 2 mid-rise office buildings with a 9.86 MW community peak power demand. This study considered 21 hybrid renewable energy cases and investigated their performance in 2 scenarios – scenario 1 without battery and scenario 2 with battery. The system performance is assessed from the technical, economic, and emission perspectives by analysing the system load matching, net present value, discounted payback period, and equivalent CO2 emission. In scenario 1, the hybrid renewable energy case 5 with 6 offshore wind turbines (12 MW) and 117 tidal stream converters (29.25 MW) has the best annual load matching (56.68% “onsite energy matching” and 57.84% “onsite energy fraction”) mainly due to their complementary generation pattern during specific periods. In scenario 2, the community-scale electricity storage significantly increases the system technical performance by raising the “onsite energy matching” and “onsite energy fraction” of case 5 to 75.25% and 74.75%, respectively. In addition, the techno-economic analysis reveals the market competitiveness of the 21 RE cases and demonstrates the significant economic impact of the FiT policy. The comparison between scenario 1 and scenario 2 indicates that the community-scale battery diminishes the operation-cycle profits but reduces the equivalent CO2 emission. Furthermore, with the current price settings, tidal stream energy generation is considered less profitable than offshore wind energy generation. This study could provide important insights into the development of coastal zero-energy communities with hybrid offshore wind and tidal stream energy generation at other locations worldwide, especially densely populated coastal cities.

Variables of influence on the fluctuation of the mood profile among professional basketball players during a competitive period

ABSTRACT In the field of sports psychology and more specifically within elite sports, the influence that mood states have on performance is of great interest. This study investigated the relationship between professional basketball variables and mood profile throughout a competitive period. Twelve professional players were divided into two groups: starting players (SP) and rotation players (RP). The Profile of Mood States (POMS) questionnaire was administered weekly for 5 weeks. The individual training load and individual match performance were controlled. The results showed that mood, energy index and game performance remained stable. The training load varied in the assessment period but did not have an influence on the player's mood. Regarding the team role, the SP scored higher POMS results than RP. There was a positive relationship between the before-match assessment of mood and performance in competition (p = .019). No relationship was found between player’s performance and mood 48 h after the game (p = .93).

Investigating the Complementarity Characteristics of Wind and Solar Power for Load Matching Based on the Typical Load Demand in China

This study explores the potential of renewable power to meet the load demand in China. The complementarity for load matching (LM-complementarity) is defined firstly. Kendall's correlation is employed to quantify the LM-complementarity. Then the complementarity characteristics on the hourly and daily time scales are analyzed. Results reveal that increasing the distance between interconnected power plants has weak improvements on the LM-complementarity in most cases. The LM-complementarity between wind and solar power is superior to that between wind or solar power generated in different regions. The hourly load demand can be effectively met by the LM-complementarity between wind and solar power. The optimal LM-complementarity scenario effectively eliminates the anti-peak regulation feature of wind power and reduces the phase differences between load demand and renewable power generation during a day. However, it is hard to balance renewable power generation and load demand on the daily time scale by the LM-complementarity. Compared with the complementarity for power smoothing defined in previous studies, the instability and peak-to-valley differences of the net-load demand can be effectively reduced by LM-complementarity. Thus the needs for flexibility are effectively reduced when integrating large-scale renewable power into the power system.

Plus energy building: Operational definition and assessment

Considering the amount of existing buildings, decarbonizing the building stock requires new buildings designed to reach the highest performance. The nearly-Zero Energy Buildings (nZEB) standard needs to be overtaken by Plus Energy Buildings (PEB) that presents the potential to produce more energy than the consumption over a specific period. Several studies investigated the potential of a building to achieve a plus energy balance, however, there is still a lack of a comprehensive and shared framework for designing and assessing the performance of a PEB. To cope with this issue, the authors identified a series of key aspects that needs to be stated in a consistent framework for PEB, and in particular: i) the balance contributions, ii) the physical boundaries, iii) the time span for the balance assessment, iv) the metrics for evaluating PEBs, v) the approach for evaluating load matching and grid interaction, vi) Indoor Environmental Quality and user satisfaction as added values of a PEB. The authors performed a comprehensive review identifying 82 papers dealing with PEB and deducing how the key aspects have been addressed. The literature overview provides the background for proposing an approach for the PEB definition and to introduce an operational assessment focused on providing the main statements focusing on PEB performance evaluation both during the design and operative phase.

Assessing the Relationship Between External and Internal Match Loads in Elite Women's Rugby Sevens.

To assess the relationship between external and internal load during official women's rugby seven matches. Six backs (age = 24.2 [3.2]y; height = 161.5 [7.3]cm; body mass = 59.5 [5.0]kg; playing experience = 5.3 [1.5]y) and 8 forwards (age = 22.4 [2.7]y; height = 167.0 [4.8]cm; body mass = 70.6 [5.6]kg; playing experience = 5.0 [1.5]y) belonging to the women's rugby seven Brazilian national team were monitored across 3 international tournaments during the 2019-20 season, with 2 players excluded from the analysis sincethey did not participate in any investigated match. Total distance (TD), distance during high-intensity running 18.1 to 20.0km·h-1 and >20km·h-1 (sprinting), number of accelerations >1.8m·s-2 (ACC), and of decelerations <1.8m·s-2 were used as match load volume measures, while their relative values (TD per minute, high-intensity running per minute, sprinting per minute, ACC per minute, and decelerations per minute) were used as external load match intensity measures. Internal load intensity and volume were assessed using the session rating of perceived exertion (sRPE) and its value multiplied by match duration (sRPE-ML), respectively. Spearman correlations and linear mixed models were used to assess the relationships between internal and external load measures. A very large relationship (ρ = .830, P < .001) was found between sRPE-ML and TD, with linear mixed models showing that TD statistically affected sRPE-ML (P < .001). Linear mixed models analysis showed that ACC per minute was also affecting the sRPE-ML (P = .017), while sprinting (P = .007) and ACC per minute (P = .005) were the only 2 measures statistically affecting sRPE. However, weak relationships (trivial to large) were found for these and all other measures. These results highlight that TD is the main external load measure able to anticipate the internal load responses measured via sRPE-ML in elite women's rugby sevens.

Energy production features of rooftop hybrid photovoltaic–wind system and matching analysis with building energy use

Rooftop photovoltaic (PV)–wind hybrid systems serve as a promising energy supply source to mitigate environmental concerns and satisfy high energy demands. Most of energy matching studies focused on the matching capability of photovoltaic generation with building load, and the application of wind power to complement PV was rarely considered. In the context, this study explored the production aspects of PV–wind turbine (WT) hybrid systems and their potential to meet building energy use demands in densely built urban areas. Both solar and wind resources in 18 cities in eastern China were classified into three energy output levels, and Hangzhou was selected as a representative city for analysis of the complementarity of the two resources. Based on the modeling of hybrid PV–wind system generation, a PV/WT production feature curve was generated by k-means clustering. The matching between renewable energy production and building energy use and the influences of different wind resources and building heights were analyzed for rooftop hybrid systems in two typical residential buildings. The results reveal that the wind and solar resources in Hangzhou are partly complementary in terms of time sequence and power output. For the multi-story and high-rise residential building considered, a rooftop hybrid PV–WT system was concluded to be beneficial in improving energy generation, reliability, and load matching performance in a limited space. The technical performance for the high-rise case was inferior to that for the multi-story case considered. In the case of residential buildings, the matching between on-site supply and load is influenced by the local wind resources and building height. The richer the urban wind resource, the greater the load cover ratio and the self-sufficiency of the installed rooftop hybrid system. However, the load matching performance declines with increasing building height. The proposed general method for analyzing rooftop hybrid PV–WT systems can enable widespread and efficient solar and wind energy utilization in densely populated and built urban areas.

Application of Electrodynamic Catalytic Reactors for Intensification of Heat and Mass Exchange Processes of Heterophase Catalysis

This article discusses a model of an electrodynamic reactor. It is fundamentally different in the way of supplying energy to the reaction zone from the reactors currently in operation in industry. This significantly reduces energy consumption, simplifies process control and increases the efficiency of the reactor. The environmental advantage of the developed reactor is also of great importance. There are no emissions of gases into the atmosphere, which are formed in large quantities during fuel combustion in superheating furnaces, the consumption of water is reduced, which is used only in a closed cycle to cool the microwave generator and circulator as a matching load during its operation. The overall efficiency of the electrodynamic reactor is 1.2 times higher than that of existing industrial ones. A method for calculating thermodynamic processes in electrodynamic reactors is proposed. It allows you to determine the technological parameters of the process to ensure a given temperature distribution and provides the maximum yield of the target reaction products with the minimum possible energy consumption of electromagnetic radiation.

A waterwheel hybrid generator with disk triboelectric nanogenerator and electromagnetic generator as a power source for an electrocoagulation system

Electrocoagulation (EC) method has emerged as a state-of-the-art water purifying technology. Here, a self-powered EC system is proposed using a waterwheel hybrid generator (W-HG) based on disk-type triboelectric nanogenerator (D-TENG) and electromagnetic generator (EMG). D-TENG consists of a rotator and stator based on printed circuit board (PCB) technology. With electrospinning and sintering process for polytetrafluoroethylene (PTFE) as a dielectric layer of the D-TENG, the fabricated membrane exhibits superhydrophobic property with a water contact angle of 160.5°, which allows the device to show self-cleaning property and to operate at high relative humidity. Additionally, a fractal-design based switched-capacitor-converter (FSCC) is utilized with the high-frequency and high-output based D-TENG to operate commercial electronic devices. The hybridized W-HG exhibits 1.75 mW of the average power at the matching load resistance of 400 Ω. An energy conversion efficiency of the device between rotational input energy and electrical output energy marks at 8.75%. The D-TENG and EMG are combined with a rotating waterwheel to demonstrate their ability to power an EC purification system. A power management integrated circuit (PMIC) is utilized with the D-TENG for high current input to the EC module. Finally, the W-HG successfully purifies wastewater with a high removal ratio above 95% for 18 h.

Assessing Responsive Building Envelope Designs through Robustness-Based Multi-Criteria Decision Making in Zero-Emission Buildings

Responsive building envelopes (RBEs) are central to developing sustainability strategies for zero emission/energy buildings (ZEBs). RBEs are a large group of complex technologies and systems, which is why multi-criteria decision making (MCDM) methods are helpful to navigate sustainability assessments considering various performance indicators. This article first provides a literature review of assessment criteria and key performance indicators for RBEs and an analysis of existing robustness-based MCDM methods. Then, a methodological approach to assess RBE designs in ZEB projects is proposed as an extension of a novel robustness-based MCDM method that normalizes the objective functions according to defined targets and combines them into one comprehensive indicator (MT-KPI), thereby eliminating the need to weight objectives. The proposed methodological approach is finally tested on a case study of a Norwegian ZEB, where five competitive RBE designs (including building integrated photovoltaics, phase change material, and electrochromic windows) and eight occupancy and climate scenarios are investigated considering three main performance areas: energy use, thermal comfort, and load matching. The results in the case study show that with the proposed MCDM approach the different designs have MT-KPI values between 1.4 and 12.8, where a lower value is better. In this specific case, the most robust building RBE alternative was identified as the one with electrochromic windows and a control based on incident solar radiation and indoor air temperature.

HlaR: A rapid and reproducible tool to identify eplet mismatches between transplant donors and recipients

Eplet mismatch load, both overall and at the single molecule level, correlates with transplant recipient outcomes. However, precise eplet assessment requires high-resolution HLA typing of both the donor and recipient. Anything less than high-resolution typing requires imputation of HLA types. The currently available methods to identify eplet mismatch are both tedious and demanding. Therefore, we developed a software package and user-friendly web application (hlaR), that simplifies the workflow of eplet analysis, provides functions to impute high-resolution from low-resolution data and calculates both overall and single molecule eplet mismatch for single or multiple donor recipient pairs. Compared to manual assessments using currently available tools (namely, HLAMatchMaker), hlaR resulted in only minimal discrepancy in eplet mismatches (mean absolute difference of 0.56 for class I and 0.86 for class II for unique sum across loci). Additionally, output of the single molecule eplet function compared well to manual calculation, with an average single antigen count increase of 0.19. Importantly, the hlaR tool permits rapid and reproducible imputation and eplet mismatch including comparison between eplet reference tables (e.g. HLAMatchMaker version 2 or 3). Users can import data from a spreadsheet rather than relying on keystroke entry of individual donor and recipient data, thus reducing the risk of data entry errors. The resulting improved scalability of the hlaR tool is highlighted by plotting analysis time against the size of the input dataset. The new hlaR tool can provide eplet mismatch data with a streamlined workflow. With decreased effort from the end user, eplet matching and mismatch load data can be further incorporated into both research and clinical use.

Numerical analysis of single-phase liquid immersion cooling for lithium-ion battery thermal management using different dielectric fluids

Lithium-ion battery (LIB) cells are responsible for powering most electric vehicles. LIB is still a superior battery available in the market because of its high energy density, specific power, and long cycle life. However, LIB comes with the challenges like thermal management as it is highly sensitive to temperature. Amongst different cooling methods, direct liquid cooling, also known as immersion cooling, can deliver a high cooling rate mainly because of its complete contact with the heat source. The single-phase liquid immersion with dielectric fluids (DELC) offers safety and cooling performance with lower parasitic power consumption and space requirements. This research involves studying and comparing different DELC's for the direct cooling of lithium-ion batteries. A numerical analysis of the 4S1P arrangement of LIB cells with direct cooling is conducted with three different DELC's including deionised water, mineral oil, and an engineered fluid. The transient behaviour of the battery module for various mass flow rates of DELC and at 1C,2C,3C-discharge rates are examined. All DELC maintains an excellent temperature homogeneity within the individual cells and LIB cells. The DELC with higher specific heat and thermal conductivity is suitable for cooling the LIB cells during high discharge conditions. However, all the dielectric fluids studied here effectively limit the temperature rise below 5 °C at 2-C discharging operation when the mass flow rate is increased to 0.05 kg/s. This improvement in thermal performance comes at the expense of extra power consumption. Even though both DELC-2 and DELC -3 delivered almost similar temperature rise values of 6.1, 5.2 °C, respectively during 2C discharging operation, the latter consumed 76.43% less power at a mass flow rate of 0.05 kg/s. For this reason, engineered fluids with lower viscosity values can be preferred over mineral oils. The deionised water is more effective for limiting the temperature rise below 2.2 °C for 3C discharging with the least parasitic power consumption of 0.52 mW at a mass flow rate of 0.05 kg/s. A variable cyclic load matching HWFET-driving cycle has been applied to the battery pack with all three DELCs, and all three fluids limited temperature rise below 1 °C.

Theoretical analysis and general characteristics for nonlinear vibration energy harvesters

In this paper, we present a systematic theoretical and numerical study of the output performance of nonlinear energy harvesters. The general analytical expression of output power for systems with different combinations of nonlinear stiffness and nonlinear damping, as well as symmetrical and asymmetrical systems, have been derived based on harmonic balance method, observing compliance with numerical results. We theoretically prove that there is a limit power for all nonlinear systems which is determined exclusively by the vibrator mass, excitation acceleration, and mechanical damping. The results also indicate that for symmetrical stiffness systems, the asymmetrical damping components have no effect on the output performance. Additionally, we derived semi-analytical solutions of the matching loads and numerically investigated the influence of nonlinear coefficients on the output power with matched load. When the load matches device parameters and is much larger than the internal resistance, the equivalent time-average damping is equal to the mechanical damping. Although the matching load and output power vary with the nonlinear coefficients, the normalized power and matching resistance ratio follow a power function, named matching power line, which is independent of the structural parameters. With the improvement of the equivalent time-average short-circuit damping in the vibration range, the normalized power moves to the right end of the matching power line, and the output power approach to the limit power. These conclusions provide general characteristics of nonlinear energy harvesters, which can be used to guide the design and optimization of energy harvesters.

Criteria and quality assessment of the matching of loads in the band-pass of polynomial LC-filter

Criteria and quality assessment of the matching of loads in the band-pass of polynomial LC-filter

Compact Load Network Having a Controlled Electrical Length for Doherty Power Amplifier

The load network of the carrier amplifier for the conventional Doherty power amplifier (DPA) consists of an impedance matching circuit, an offset line, and a &#x03BB;/4 transmission line (TL), so that the overall electrical length of the network can easily exceed the minimum value of 90&#x00B0;. Then for appropriate impedance modulation, it should be 270&#x00B0; with an additional 180&#x00B0;. This excessive electrical length of the load matching network limits the bandwidth at either the low-power or peak-power level. In this paper, a compact quasi-lumped &#x03BB;/4 impedance transformer (ITF) having simultaneous multiple functions of impedance matching and load impedance modulation with a controlled electrical length of 90&#x00B0; is presented. The proposed load network includes the internal components of the transistor, the simplest high-pass network using a shunt inductor, and a low-pass L-C network. Using the optimized value of the shunt inductor, the electrical length of the load network can be adjusted to 90&#x00B0;, while other components are accordingly changed to match the optimum load impedance. To verify the proposed load network, a DPA was designed and implemented using 10 W GaN-HEMTs for both carrier and peaking amplifiers. Using a 5G New Radio (NR) signal with signal bandwidth of 100 MHz and peak-to-average power ratio (PAPR) of 7.8 dB, a drain efficiency (DE) of 47 - 54.2%, and adjacent channel leakage power ratio (ACLR) of &#x2013;27.9 - &#x2013;23 dBc were achieved at an average output power level of 35.8 - 36.3 dBm for the frequency band of 3.4 - 3.8 GHz.

Sensitivity Analysis of Data Size in Pca Fault Detection Method Combining with Thermal Load Matching and Data Window Strategy

Sensitivity Analysis of Data Size in Pca Fault Detection Method Combining with Thermal Load Matching and Data Window Strategy

Impact of time resolution averaging analysis on integrated photovoltaic with office buildings and grid interaction metrics: Case study

The matching of the photovoltaic (PV) power generation profile with that of the office building is very vital to improving the self-consumption index and the building’s self-sufficiency degree. This study focuses on grid interaction and load matching metrics of office building integrated PV systems. The test system in this study is an 8 kWp grid connected PV system located at the Electronics Research Institute (ERI), Giza, Egypt. Different data on the PV inverter output side and those between the load and the grid are measured at different time steps to investigate the effect of the different time steps on the performance and sizing of the utilized PV array, through estimating the maximum PV power and the load power, as well as the metrics that measure the proper match between the grid interaction and the load. The entire process is based on the application of time series clustering as a data-driven technique in order to examine the average PV and load power profiles. In addition, two technique, which are time series clustering and trailing moving average, are used to compare the resulted hourly average PV output powers for the considered different time steps. Finally, the results of the estimated capacity factor and self-consumption/sufficiency metrics of the considered PV system are indicated to significantly affect the optimal size of the utilized PV array by satisfying the desired requirements of the net zero energy buildings and enhancing the performance of the utilized PV system.

Maximum Electrical Power Extraction from Sources by Load Matching

This paper describes the matching of various loads to sources (including nonlinear ones). The purpose of matching is to extract the maximum available power from the source. This has particular importance for renewable sources and energy-harvesting devices, in which unused energy is just wasted. The main innovations in this paper include (and followed by examples) simplified calculation of the matching parameter for a controllable load and matching by means of a family of power-conservative two-port networks, denoted POPI (Pin = Pout), such as transformers, gyrators, loss-free resistors (LFRs) and series LFRs (SLFRs). An additional innovation described in this paper is a new, simplified model of an HF power amplifier based on the series LFR concept. This model predicts that the efficiency of the HF power amplifier operated under the matched-mode condition can significantly exceed the 50% efficiency limit that is predicted by the conventional model. As HF power amplifiers drive antennas in transmission and some wireless power transfer (which uses radiative techniques) systems, it is clear that the operation of such systems in the matched-mode condition is not restricted to a 50% efficiency limit.

Achieving smooth motion and high-speed for piezoelectric stick-slip actuator based on the two-stage lever principle.

With the development of the precision manufacturing industry, actuators' performance requirements are increasingly demanding. However, stick-slip actuators still have the problems of backward motion and low motion speed at low frequencies. In this paper, to decrease the backward motion and achieve high speed at low frequencies, a linear piezoelectric stick-slip actuator is designed based on the two-stage lever principle. Theoretical and numerical investigations are used to optimize the flexible hinge of the stick-slip actuator. Experimental results indicate that the motion slider can achieve a smooth motion. The backward rate can even drop to 0. The maximum motion speed was 124.83 mm/s at 1600 Hz. The motion speed of the designed actuator was higher than that of previous stick-slip actuators at the same frequency. In addition, the load capacity of the prototype is tested. Based on different loads, the load matching is achieved by an auxiliary piezoelectric-stack, where the maximum horizontal load was 2.3 N. According to the comparison with previous actuators, the designed prototype can achieve high speed at low frequencies. Furthermore, the displacement curves show good smoothness. These characteristics will be helpful for the practical application of stick-slip piezoelectric actuators.

Energy hub-based optimal planning framework for user-level integrated energy systems: Considering synergistic effects under multiple uncertainties

The design of user-level integrated energy systems is challenged by a variety of combinations of energy converters, complex cascade utilization of multiple energy flows, as well as sequential matching between stochastic energy resources and periodic energy demands. These issues can be addressed by an optimal energy-hub based planning framework considering the synergistic effects under multiple uncertainties. The energy hub model is extended to analyze energy-level matching and source–load balance with time-varying coupling factors representing part-load characteristics. The optimization problem is formulated as a bi-level planning model with uncertainties evaluated by a two-stage global sensitivity analysis. The bi-level planning model determines the system structure and component sizing at the upper level and identifies the optimal operation strategy at the lower level by employing piecewise linearization of part-load characteristics of components involved. The global sensitivity analysis reduces model size with the elementary effect method, identifies the most influential uncertain parameters with a variance-based method. A case study in Beijing is demonstrated for the proposed methodology. The results show that the proposed method can effectively plan the integrated energy system considering sequential source–load matching with the rational scheduling strategy of components. The demand-side response influences the system configuration and renewable energy penetration. Integrating the components’ part-load characteristics help avoid the mismatch between the component capacity and energy demand, reducing 6.8% cost compared to the scheme with constant energy efficiency. The three most influential factors identified among 551 uncertain parameters are natural gas price, valley electricity price and nominal efficiency of the gas turbine.