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The effect of dynamic solar heat load on the greenhouse microclimate using CFD simulation
摘要： Indoor greenhouse temperature exceeds tolerable range for plants growth mostly during the summer in Ahvaz-Iran. Attempts for improving ventilation in summer was not adequate despite a huge energy consumption. Computational fluid dynamic models of a full scaled gable greenhouse covered by semitransparent materials among several adjacent greenhouses inside a greenhouse paradise for predicting the dynamics of its microclimate during a day as well as a year 2017-2018 were developed. The accuracy of the models was approved by comparing to the physical experiments and meteorological reports. The results approved the capability of the model for predicting variable solar heat load and higher indoor temperature than ambient in several hours of a day as well as surface heat transfer coefficient of the walls as affected by regional dominant wind profile. This study enhanced the understanding of required solar heat load removal during the hot months while the average temperature exceeds 40 °C for more than 11 hours a day. This finding also indicates the critical periods in which the fan assisted natural ventilation system can be applied to cool down the greenhouse from more than 40 °C to 25 to 35 °C.
关键词： Greenhouse,Temperature distribution,Modeling,Solar radiation,Dynamic microclimate,CFD
更新于2025-09-19 17:15:36
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Review—System-on-Chip SMO Gas Sensor Integration in Advanced CMOS Technology
摘要： The growing demand for the integration of functionalities on a single device is peaking with the rise of IoT. We are near to having multiple sensors in portable and wearable technologies, made possible through integration of sensor fabrication with mature CMOS manufacturing. In this paper we address semiconductor metal oxide sensors, which have the potential to become a universal sensor since they can be used in many emerging applications. This review concentrates on the gas sensing capabilities of the sensor and summarizes achievements in modeling relevant materials and processes for these emerging devices. Recent advances in sensor fabrication and the modeling thereof are further discussed, followed by a description of the essential electro-thermal-mechanical analyses, employed to estimate the devices’ mechanical reliability. We further address advances made in understanding the sensing layer, which can be modeled similar to a transistor, where instead of a gate contact, the ionosorped gas ions create a surface potential, changing the film’s conduction. Due to the intricate nature of the porous sensing films and the reception-transduction mechanism, many added complexities must be addressed. The importance of a thorough understanding of the electro-thermal-mechanical problem and how it links to the operation of the sensing film is thereby highlighted.
关键词： SMO gas sensors,CMOS integration,sensing mechanism,modeling,microheater design
更新于2025-09-19 17:15:36
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Theoretical and experimental studies on DC conductivity and temperature-dependent AC conductivity of poly(butyl methacrylate)/Nd-TiO <sub/>2</sub> nanocomposites
摘要： Electrically conductive nanocomposite system based on poly(butyl methacrylate) (PBMA) with different contents of neodymium-doped titanium dioxide (Nd-TiO2) was prepared by in situ free radical polymerization method. The effect of Nd-TiO2 on the morphology and structural properties of the composites was carried out by scanning electron microscope (SEM) and X-ray diffraction analysis (XRD). The temperature-dependent AC conductivity and DC electrical conductivity of PBMA/Nd-TiO2 nanocomposites were studied with respect to the different volume fraction of Nd-TiO2 nanoparticles. SEM and XRD patterns revealed the uniform dispersion and structural regularity of nanoparticles in the polymer matrix. The AC conductivity of PBMA and its composites were found to be increased with an increase in temperatures and frequencies. The activation energy and exponential factor were analyzed from AC conductivity and both results indicate the hopping conduction mechanism present in PBMA/Nd-TiO2 nanocomposite, which is responsible for the variation of conductivity with temperature also. The DC conductivity of nanocomposites was higher than pure PBMA and the conductivity increases with increase in the concentration of Nd-TiO2 nanoparticles. Experimental and theoretical investigations based on McCullough, Bueche, Scarisbrick, and Mamunya modeling were carried out to observe the DC conductivity differences induced by the addition of Nd-TiO2 nanoparticles in PBMA matrix. Among the various modeling studied here, Mamunya model shows better agreement with the experimental conductivity.
关键词： Poly(n-butyl methacrylate),DC conductivity,conductivity modeling,temperature-dependent AC conductivity
更新于2025-09-19 17:15:36
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Capability of Spaceborne Hyperspectral EnMAP Mission for Mapping Fractional Cover for Soil Erosion Modeling
摘要： Soil erosion can be linked to relative fractional cover of photosynthetic-active vegetation (PV), non-photosynthetic-active vegetation (NPV) and bare soil (BS), which can be integrated into erosion models as the cover-management C-factor. This study investigates the capability of EnMAP imagery to map fractional cover in a region near San Jose, Costa Rica, characterized by spatially extensive coffee plantations and grazing in a mountainous terrain. Simulated EnMAP imagery is based on airborne hyperspectral HyMap data. Fractional cover estimates are derived in an automated fashion by extracting image endmembers to be used with a Multiple End-member Spectral Mixture Analysis approach. The C-factor is calculated based on the fractional cover estimates determined independently for EnMAP and HyMap. Results demonstrate that with EnMAP imagery it is possible to extract quality endmember classes with important spectral features related to PV, NPV and soil, and be able to estimate relative cover fractions. This spectral information is critical to separate BS and NPV which greatly can impact the C-factor derivation. From a regional perspective, we can use EnMAP to provide good fractional cover estimates that can be integrated into soil erosion modeling.
关键词： EnMAP,Costa Rica,imaging spectroscopy,soil erosion modeling,spectral mixture analysis
更新于2025-09-19 17:15:36
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Metasurfaces for Advanced Sensing and Diagnostics
摘要： Interest in sensors and their applications is rapidly evolving, mainly driven by the huge demand of technologies whose ultimate purpose is to improve and enhance health and safety. Different electromagnetic technologies have been recently used and achieved good performances. Despite the plethora of literature, limitations are still present: limited response control, narrow bandwidth, and large dimensions. MetaSurfaces, artificial 2D materials with peculiar electromagnetic properties, can help to overcome such issues. In this paper, a generic tool to model, design, and manufacture MetaSurface sensors is developed. First, their properties are evaluated in terms of impedance and constitutive parameters. Then, they are linked to the structure physical dimensions. Finally, the proposed method is applied to realize devices for advanced sensing and medical diagnostic applications: glucose measurements, cancer stage detection, water content recognition, and blood oxygen level analysis. The proposed method paves a new way to realize sensors and control their properties at will. Most importantly, it has great potential to be used for many other practical applications, beyond sensing and diagnostics.
关键词： MetaSurface,sensors,cancer detection,modeling,medical diagnostics,glucose measurements,design
更新于2025-09-19 17:15:36
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Analysis of vulnerability propagation for the all-optical network based on Bio-PEPA
摘要： Aiming at the vulnerability propagation of all-optical networks, combining with the characteristics of the all-optical network, a formal modeling and analysis method for vulnerability propagation based on Bio-PEPA is proposed in this paper. First of all, the main characteristics that influence the vulnerability propagation are analyzed. Then, the optical fibers, optical amplifiers and optical switches are abstract into three different clusters, and the propagation behavior of vulnerability in intra-cluster and inter-cluster are described accurately. In addition, Ordinary Differential Equations is used for model parsing. Finally, through testing the main factors of vulnerability propagation, such as the number of nodes with potential vulnerability, system detection and repair rate, it is shown that the model constructed in this paper can reflect the vulnerability propagation trend of all-optical networks reasonably. At the same time, the proposed method can avoid the state space explosion problem of traditional modeling methods.
关键词： Bio-PEPA,Formal modeling,All-optical network,Vulnerability propagation
更新于2025-09-19 17:15:36
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High-resolution, parametric BIPV and electrical systems modeling and design
摘要： The design of building integrated photovoltaics (BIPV) often involves complex geometries, non-uniform irradiance conditions and partial shading. This can lead to high energy losses if not considered adequately. This paper presents a BIPV modeling and optimization method which uses a parametric 3D modeling tool, coupled to a high-resolution ray-tracing irradiance simulation and an electrical model based on the single diode model on a subcell level. With the use of a genetic algorithm, electrical interconnections of the modules are optimized for maximum yield. The presented approach allows the simulation and optimization of BIPV in urban environments where complex shading occurs and high electrical mismatch of photovoltaic cells and modules is to be expected. It allows specific geometric design and optimization of photovoltaic installations and their electrical layout. The electrical simulation is validated for both flat and curved thin-film CIGS modules, as well as for two connected thin-film CIGS modules under deferring irradiance and partial shading conditions. The presented method is further applied in a case study on a double-curved roof shell. The results show that by using genetic algorithms the layout can be optimized to minimize the string mismatch losses for BIPV networks with a variety of modules. The detailed electrical simulation allows to quantify effects of module designs and inverter concepts on the system performance. This is demonstrated for the case study, indicating that thin-film modules with longitudinal cell direction outperform modules with orthogonal cell direction by up to 8%. Furthermore, module-integrated bypass diodes show little benefits for the best performing module technologies. Post-processing the results allows the evaluation of annual, seasonal, daily and hourly losses on a highly disaggregated level.
关键词： BIPV,Parametric analysis,High-resolution modeling,Optimization
更新于2025-09-19 17:15:36
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Phase-field modeling of domain evolution in ferroelectric materials in the presence of defects
摘要： The properties of ferroelectric devices are strongly influenced, besides crystallographic features, by defects in the material. To study this effect, a fully coupled electromechanical phase-field model for 2D ferroelectric volume elements has been developed and implemented in a Finite Element code. Different kinds of defects were considered: holes, point charges and polarization pinning in single crystals, as well as grain boundaries in polycrystals, without and with additional dielectric interphase. The impact of the various types of defects on the domain configuration and the overall coercive field strength is discussed in detail. It can be seen that defects lead to nucleation of new domains. Compared to the energy barrier for switching in an ideal single crystal, the overall coercive field strength is significantly reduced towards realistic values as they are found in ferroelectric devices. Also the simulated hysteresis loops show a more realistic shape in the presence of defects.
关键词： polycrystalline ferroelectric,phase-field modeling,microstructural defects
更新于2025-09-19 17:15:36
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[IEEE 2019 International Seminar on Electron Devices Design and Production (SED) - Prague, Czech Republic (2019.4.23-2019.4.24)] 2019 International Seminar on Electron Devices Design and Production (SED) - Thermal model of Zeeman ring laser
摘要： This paper is concerned with modeling of networks with an extremely large number of components using partial differential equations (PDEs). This modeling method is based on the convergence of a sequence of underlying Markov chains of the network indexed by N, the number of components in the network. As N goes to in?nity, the sequence converges to a continuum limit, which is the solution of a certain PDE. We provide suf?cient conditions for the convergence and characterize the rate of convergence. As an application, we model large wireless sensor networks by PDEs. While traditional Monte Carlo simulation for extremely large networks is practically infeasible, PDEs can be solved with reasonable computation overhead using well-established mathematical tools.
关键词： Markov processes,network modeling,partial differential equations,Modeling
更新于2025-09-19 17:13:59
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[IEEE 2019 5th International Conference on Advances in Electrical Engineering (ICAEE) - Dhaka, Bangladesh (2019.9.26-2019.9.28)] 2019 5th International Conference on Advances in Electrical Engineering (ICAEE) - Analysis of Photovoltaic Characteristics of Carbon Nanotube Incorporated Perovskite Solar Cell with CNT Chirality Variation
摘要： In the advanced manufacturing industry, planar switched reluctance motors (PSRMs) have proved to be a promising candidate due to their advantages of high precision, low cost, low heat loss, and ease of manufacture. However, their inverse force function, which provides vital phase current command for precise motion, is highly nonlinear and hard to be accurately modeled. This paper proposes a novel inverse force function using sparse least squares support vector machines (LS-SVMs) to achieve nonlinear modeling for precise motion of a PSRM. The required training and testing sets of sparse LS-SVMs are ?rst obtained from experimental measurement. A sparse LS-SVMs regression is further developed using training set to accurately model the inverse force function. Accordingly, the function is tested via the testing set to assess its feasibility. Finally, the proposed approach is applied to the PSRM system with dSPACE controller for trajectory tracking, and its effectiveness and superior performance are veri?ed through experimental results.
关键词： Inverse force function,least squares support vector machines (LS-SVMs),phase current estimation,nonlinear modeling,planar switched reluctance motors (PSRMs)
更新于2025-09-19 17:13:59