Modeling Hybrid Hydro-Electro-Mechanical Power-Split Propulsion Systems

Hydrostatic and hydro-mechanical transmissions (HSTs and HMTs, respectively) are commonly used in off-highway vehicles. While both transmission technologies can provide continuously variable torque or speed ratios, they suffer from poor efficiencies and limited operating ranges. Electric variable transmissions (EVTs), in contrast, offer complementary strengths via higher efficiencies at low forward and reverse speeds, full torque from zero to full power, and increased control capabilities. While HST, HMT, and EVT powertrain architectures are not novel, the authors are not aware of work integrating these technologies into hydro-electro-mechanical (HEMT) transmission architectures. Thus, this research aimed to develop a physical modeling methodology to explore different power-split transmission technologies using hydraulic, electrical, and mechanical pathways to understand how the complementary nature of the technologies could be used for overall power transmission performance. Steady-state modeling was performed using the Modelica® (Modelica Association) modeling language in the Dymola (Dassault Systems®) integrated development environment. Overall efficiency vs. output speed was presented for HMT, EMT, and HEMT input-coupled architectures, including circulating power considerations. This research extends the state-of-the-art of off-road powertrain technologies by providing the literature an exemplar modeling of HEMT coupling techniques, system integration, and power flow architectures in Modelica® modeling language.

A Novel Single-Switch High Step-Up DC–DC Converter with Three-Winding Coupled Inductor

This paper introduces a single-switch, high step-up DC–DC converter for photovoltaic applications such as power optimizers and microinverters. The proposed converter employs two voltage multipliers cells with switched capacitor and magnetic coupling techniques to achieve high voltage gain. This feature, along with a passive clamp circuit, reduces the voltage stress across the switch, allowing for the employment of low RDSon MOSFET. This leads to low conduction loss of the switch. The diodes operate with zero-current switching at their turn-off transition, eliminating the reverse recovery losses. Additionally, the switch turns on with zero-current switching, leading to insignificant switching loss associated with its turn-on transition. The operation principle and steady-state analysis are presented and validated through experimental results obtained from a 140 W prototype of the proposed converter.

Presentation of Coupling Analysis Techniques of Maximum and Minimum Values Between N Sets of Data Using Matrix [µ][MKN]

This paper deals with the presentation and study of alternative coupling techniques for maximum and minimum values between data sets, namely the problem which is examined in this work is the possible appearance of maximum or minimum values between data sets in the same or neighboring time points. The data can be time-dependent (time series) or non-time-dependent. In this work, the analysis is focused on time series and novel indices are defined in order to measure whether the values of N sets of data display in terms of time, the maximum or minimum values at the same instances or at very close instances. For this purpose, two methods will be compared, one direct method and one indirect method. The indirect method is based on Matrices of dimensionless indicators which are denoted by [μ][MKN], and the direct method is based on a variance-type measure which is denoted by [V][MKN].

State-of-the-art numerical fluid–structure interaction methods for aortic and mitral heart valves simulations: A review

Numerical fluid–structure interaction (FSI) methods have been widely used to predict the cardiac mechanics and associated hemodynamics of native and artificial heart valves (AHVs). Offering a high degree of spatial and temporal resolution, these methods circumvent the need for cardiac surgery to assess the performance of heart valves. Assessment of these FSI methods in terms of accuracy, realistic modeling, and numerical stability is required, which is the objective of this paper. FSI methods could be classified based on how the computational domain is discretized, and on the coupling techniques employed between fluid and structure domains. The grid-based FSI methods could be further classified based on the kinematical description of the computational fluid (blood) grid, being either fixed grid, moving grid, or combined fixed–moving grid methods. The review reveals that fixed grid methods mostly cause imprecise calculations of flow parameters near the blood–leaflet interface. Moving grid methods are more accurate, however they require cumbersome remeshing and smoothing. The combined fixed–moving grid methods overcome the shortcomings of fixed and moving grid methods, but they are computationally expensive. The mesh-free methods have been able to encounter the problems faced by grid-based methods; however, they have been only limitedly applied to heart valve simulations. Among the coupling techniques, explicit partitioned coupling is mostly unstable, however the implicit partitioned coupling not only has the potential to be stable but is also comparatively cheaper. This in-depth review is expected to be helpful for the readers to evaluate the pros and cons of FSI methods for heart valve simulations.

Multi-band planar diplexers with sub-sets of frequency-contiguous transmission bands

A class of multi-band planar diplexer with sub-sets of frequency-contiguous transmission bands is reported. Such a radio frequency (RF) device is suitable for lightweight high-frequency receivers aimed at multi-band/multi-purpose mobile satellite communications systems. It consists of two channelizing filters, each of them being made up of the in-series cascade connection of replicas of a constituent multi-passband/multi-embedded-stopband filtering stage. This building filtering stage defines a multi-passband transfer function for each channel, in which each main transmission band is split into various sub-passbands by the multi-stopband part. In this manner, each split passband gives rise to several sub-passbands that are imbricated with their counterpart ones of the other channel. The theoretical RF operational principles of the proposed multi-band diplexer approach with sub-sets of imbricated passbands are detailed by means of a coupling–routing–diagram formalism. Besides, the generation of additional transmission zeros in each channelizing filter for higher-selectivity realizations by exploiting cross-coupling techniques into it is also detailed. Furthermore, for experimental demonstration purposes, a microstrip proof-of-concept prototype of second-order octo-band diplexer in the frequency range of 1.5–2.5 GHz that consists of two quad-band channelizing filters with pairs of imbricated passbands is developed and characterized.

Effects of Humic Acid-Irrigation Coupling Techniques on Temperature, Radiation and Rice Growth in Songnen Plain China

In the past decades, the application of organ fertilizer in agricultural soils has attracted wide attention. However, few studies have carefully explored the effects of humic acid on soil and canopy temperature, radiation, the physiological process of plant leaves, especially coupling with the different irrigation methods. To provide a better growing environment for crops and explore the best regulation mode of humic acid and irrigation coupling techniques in the farmland soil environment in the Songnen Plain Heilongjiang Province, through field experiment, we selected rice as the test crop and applied humic acid in the soil with different irrigation methods. The temperature conditions, radiation, agronomic and fluorescence characteristics were monitored by different stages. The effects of different humic acid and irrigation coupling techniques on the temperature and radiation changes during different growth stages were discussed, and the subtle differences of agronomic and fluorescence characteristics in different growth stages of rice plants were compared. The results showed that the humic acid application with different irrigation methods was not beneficial to the maintenance of soil temperature, the differences among the different treatments, were no found significant at 5% probability statistically. However, the differences of radiation interception was obvious, and the best value was CT5 treatment, there were also similarities to plant height. The fluorescence indexes and leaf chlorophyll relative content (SPAD) had the differences with the change of humic acid application rate and irrigation methods. Over all, under the humic acid application rate of 1500 kg·ha-1 with the control irrigation method, could bring the best humic acid and irrigation effects.