The wind turbine power curve (WTPC) is a mathematical model built to capture the input-output relationship between the generated electrical power and the wind speed. An adequately fitted WTPC aids in ...wind energy assessment and prediction since the actual power curve will differ from that provided by the manufacturer due to a variety of reasons, such as the topography of the wind farm, equipment aging, and multiple system faults. As such, this paper introduces a novel approach for WTPC modeling that combines Gaussian process (GP) regression, a class of probabilistic kernel-based machine learning models, and standard logistic functions. This semi-parametric approach follows a Bayesian reasoning, in the sense of maximizing the marginal likelihood to learn the parameters and hyperparameters through a variational sparse approximation to the GP model. Using real-world operational data, the proposed approach is compared with the state-of-the-art in WTPC modeling and with an alternative probabilistic approach based on generalized linear models and logistic functions. Finally, we evaluate the proposed model in its extrapolation ability for unmodelled data.
•Logistic function parametrization derived from Wind Turbine operational ranges.•Analytical procedure of parameter initialization in logistic function models.•Novel Semi-Parametric model capable of adaptation to training data and extrapolation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Earlier sowing date increased carrying capacity of intercropped maize, enhancing its resilience towards size-asymmetric competition.•Intercropped maize sown earlier increased the grain yield by ...21–42%, closing its gap with sole maize yield.•A rational sowing date raised the crop’s aggressivity whilst without costing the yield of the coexisting crop.
Intercropping is becoming an attractive and profitable agricultural practice, and a growing body of literature investigate on the plant–plant interaction between intercrops. However, little is known on how sowing date alters interspecific interaction causing a yield difference between the intercropped and sole crop. A two-year field experiment was undertaken to investigate the impacts of varying competitive interaction on plant growth and grain yield of a maize/watermelon intercropping system. Both intercropped and sole maize were sown 28 days, 33 days and 38 days after a consistent transplanting date for watermelon to generate varying intensities of asymmetric competition between species in the maize/watermelon intercropping system. Growth patterns were monitored over two years and described with logistic growth curves. Compared with conventional sowing date, changes in maize sowing date significantly enhanced the intercropped maize grain yield by 21%–42%, but barely affected the sole maize yield, consequently reducing the yield difference between intercropped and sole maize. An earlier sowing date empowered the intercropped maize to reach the maximum absolute growth rate 11 days earlier, producing greater aboveground biomass and larger growth rate over its growing period, and thereby enhanced the maize resilience towards size-asymmetric competition derived from the presence of watermelon. Changes in the maize sowing date did not alter the fruit yield of intercropped watermelon in the most cases, but overmuch improvement in the aggressivity and growth rate of the maize sown on 13 June in 2014 caused a 16% reduction in fruit yield. We concluded that the yield difference can be reduced by adjusting the sowing date to manipulate plant–plant interaction between intercrops, and an optimal sowing date not only enhances crop growth but also brings on no penalty on companion crop yield.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The logistic function is shown to be solution of the Riccati equation, some second-order nonlinear ordinary differential equations and many third-order nonlinear ordinary differential equations. The ...list of the differential equations having solution in the form of the logistic function is presented. The simple method of finding exact solutions of nonlinear partial differential equations (PDEs) is introduced. The essence of the method is based on comparison of nonlinear differential equations obtained from PDEs with standard differential equations having solution in the form of the logistic function. The wide application of the logistic function for finding exact solutions of nonlinear differential equations is demonstrated.
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•Detection method and driving strategy of shape memory alloy wires are discussed.•An improved phase transformation equation with the Logistic function is proposed.•SMA wires electric ...resistance and its rate are studied in theory and experiment.•Phase transformation start/end points are detected by electric resistance method.•Optimized driving strategy is proposed to reduce power consumption of SMA wires.
To propose a novel driving strategy for power consumption reduction, this paper studies the electric resistance behaviors of shape memory alloy (SMA) wires, which are heated by the short-time large current. With a concern for the relationship between electric resistance and shape memory effect, an improved phase transformation equation with the Logistic function is proposed. Moreover, based upon electric resistance and its rate, a new detection method for the driving strategy of SMA wires is proposed. The proposed method is compared with the traditional deformation detection method. The results show that the method effectively resists the interference of system noise and captures the start and end points of phase transformation. To assess the deformation response of SMA wires by the proposed method, constant load tests are conducted, which are applied with the periodic excitation signals of triangular wave, sine wave, and square wave, respectively. The experimental results show the square wave is more suitable for driving the SMA wire actuator. The heating and cooling cycle experiment verifies the effectiveness of the proposed method. Compared with the method using pulse width modulation signals, the proposed method reduces power consumption obviously, and does not need external sensors or material parameters. Based on the proposed method, the power consumption can be reduced by the optimized driving strategy, which improves the lightweight and reliability of SMA actuators.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•WEEE generated in Vietnam during the period 2015–2050 was estimated.•Three scenarios in terms of lifespan were analyzed.•The relationship between lifespan and GDP per capita was considered.•The ...uncertainties related to the lifespan were covered to some extent.
During recent decades, rapid urbanization, an increase in population, and a change in lifestyle have generated a significant amount of waste electrical and electronic equipment (WEEE). To develop sustainable and efficient WEEE management policies, particularly in developing countries such as Vietnam, it is of paramount importance to forecast the amount of WEEE generation expected in the future. In the input-output approach as one of the WEEE estimation models, the determination of EEE lifespan is a major concern because it can be dynamic with time and vary with socioeconomic situations. Therefore, three scenarios were considered on the basis of the association of lifespan with gross domestic product per capita. By considering the lifespan transition, this study estimated the potential amount of WEEE, particularly large home appliances including refrigerators, washing machines, air conditioners, and televisions generated in Vietnam and the relative volume of obsolete metals contained in the WEEE during the period 2015–2050. For this, it employed a population balance model, logistic function, and Weibull distribution. It was found that the estimated weight of WEEE discarded in Vietnam during 2050 is mitigated 50% under the case where the lifespan transition is considered, compared to the case where the lifespan transition is not considered. By considering the relationship between lifespan and GDP per capita in estimating potential WEEE, this study to some extent covered the uncertainties related to the lifespan and can consequently contribute to the enhancement of e-waste estimation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Clothing adjustment is an essential way for people to adapt to the weather changes and maintain thermal comfort in an outdoor environment. In this study, it was assumed that outdoor clothing ...adjustment was influenced by the local past temperatures. With temperature changes, clothing adjustment could be divided into “free adjustment phase” and “restricted adjustment phase”. Two consecutive years of outdoor field investigation experiments were conducted in 6 typical outdoor spaces in Changsha, China, which was hot in summer and cold in winter. During the field experiment, outdoor thermal environment parameters were measured in real-time, meanwhile, clothing and thermal comfort of participants were documented. The analysis results of field experiment data verified the assumption. 7876 effective samples were collected to build a creative outdoor clothing model (OCM) considering the weather characteristics of Changsha based on running mean temperature and four-parameter logistic function. The determination coefficient (R2) of the OCM was 0.954, which was higher than the existing models. Moreover, prediction deviations were within 20% for 86% samples. According to the OCM, the range of running mean temperature corresponding to the free adjustment phase was 4 °C–24 °C for the Changsha residents. The free changes of clothing insulation during this phase enabled people to maintain thermal comfort in the outdoor environment. The OCM proposed in this study can provide a theoretical basis for evaluating outdoor thermal comfort and wearing appropriately according to the temperature.
●Clothing adjustment is the most essential means of thermal adaptation outdoors●Outdoor clothing adjustment is influenced by the local past temperatures●Clothing adjustment was divided into free and restricted adjustment phases●A logistic function clothing model was proposed based on running mean temperature●Clothing adjustment has a feedback effect on thermal comfort in outdoor environment
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We study a genetic model (including gene regulatory networks) consisting of a system of several ordinary differential equations. This system contains a number of parameters and depends on the ...regulatory matrix that describes the interactions in this multicomponent network. The question of the attracting sets of this system, which depending on the parameters and elements of the regulatory matrix, isconsidered. The consideration is mainly geometric, which makes it possible to identify and classify possible network interactions. The system of differential equations contains a sigmoidal function, which allows taking into account the peculiarities of the network response to external influences. As a sigmoidal function, a logistic function is chosen, which is convenient for computer analysis. The question of constructing attractors in a system of arbitrary dimension is considered by constructing a block regulatory matrix, the blocks of which correspond to systems of lower dimension and have been studied earlier. The method is demonstrated with an example of a three-dimensional system, which is used to construct a system of dimensions twice as large. The presentation is provided with illustrations obtained as a result of computer calculations, and allowing, without going into details, to understand the formulation of the issue and ways to solve the problems that arise in this case.
In the evaluation of magnetic field data, edge enhancement and detection techniques are important treatments for the interpretation of geological structures. In general geological sense, contiguity ...of deep and shallow magnetic sources leads to weak and intense anomalies that complicates the interpretation to disclose adjacent anomalous sources. Many of the existing filters for edge detection in magnetics mostly have the disadvantage that they require a reduction to pole transformation as the pre-process of the data or they cannot balance weak and intense anomalies and therefore fail in detecting edges of deep and shallow sources simultaneously. This study presents an improved edge detection filter LAS (logistic function of the analytical signal), based on the generalised logistic function configured by the ratio of derivatives of the analytical signal. This novel approach has the capability of reducing the dependence on the direction of the magnetization and also balancing anomalies of sources at different levels of depth. The feasibility of the method is examined on both theoretical and real data cases comparatively with some other methods that utilize the analytical signal in their basis. In comparison, the results demonstrate that the LAS method provides more accurate estimation of edge localization.
A three-part series presents the development of models for predicting the local thermal sensation (Part I) and local comfort (Part II) of different parts of the human body, and also the whole-body ...sensation and comfort responses (Part III). The models predict these subjective responses to the environment from thermophysiological measurements or predictions (skin and core temperatures). The models apply to a range of environments: uniform and non-uniform, transient and stable. They are based on diverse results from the literature and from body part-specific human subject tests in a climate chamber. They were validated against a test of passengers in automobiles. This series is intended to present the rationale, structure, and coefficients for these models so that others can test and develop them further as additional empirical data becomes available. The experimental methods and some measured results from the climate chamber tests have been published previously.
Part I describes thermal sensation models representing 19 individual local body parts. The models' structure and coefficients were derived by regression of skin and core temperatures against thermal sensation votes obtained in the chamber experiments. The sensation for each local body part is predicted by a logistic function with four inputs: local skin temperature, mean-skin temperature presenting the whole-body thermal state, and the time derivatives of skin and core temperatures representing the response to transients. These inputs can be obtained from thermophysiological computer programs that treat the body as multiple segments.
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This paper introduces a spatial queueing model for a single bottleneck during morning peak hours. Utilizing the logistic function and after appropriate calibration, it articulates the arrival and ...departure flows in continuous, differentiable terms. By validating the model across different peak periods and locations, the demand model’s robustness is superior to other commonly used functions. This model also incorporates constant or varying capacity scenarios. It effectively captures key aspects of morning peak traffic, including the emergence of hysteresis loops in fundamental diagrams (FDs) of density and flow. The model’s multi-stage approach recognizes three distinct phases in traffic flow: freeflow, transition, and queued segments, ensuring spatial consistency in flow and density across these stages. It accounts for the growth of the queued segment and vehicle spillback under various bottleneck intensities, with the resulting FDs for speed and density also displaying hysteresis loops. The calibration of model parameters utilizes time-series data of traffic flow and density space–time maps derived from real-world data. The validation results accurately reflect real traffic scenarios, emulating the counterclockwise hysteresis loops observed in density and its heterogeneity, and provide both planar and three-dimensional FDs at different points along the traffic link, each mirroring real-life traffic patterns. Additionally, a comparison with the cell transmission model (CTM) reveals that the proposed model exhibits superior generalization and robustness.
•Accurate capture of peak traffic patterns with logistic model.•Spatially continuous multi-stage queueing approach.•Precise replication of hysteresis loops.•Concise model with superior performance to benchmarks.
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