Engineered cementitious composites (ECC) have attracted significant attention, in the civil engineering domain, due to their appealing characteristics. A main factor governing ECC’s performance is ...the steel-to-concrete bond behavior. However, there is yet dire need to mend the knowledge gap in this venue. This study aims to investigate the influence of the ECC associated traits onto the aforementioned bond behavior: compressive strength, bonded length-to-rebar ratio, rebar diameter, ECC cover thickness (and confinement level around steel rebar at bonded length region). To fulfill this purpose, eight beam-end specimens were prepared and tested. Results showed that (i) ECC compressive strength had the greatest impact on the ultimate bond stress; followed by (ii) the bonded length-to-diameter ratio, and (iii) the cover thickness (whilst adding steel stirrups). The latter’s performance was marginal. In descending order, the influence amounted to 16.5 %, 12 % and 3.5 %, respectively, for a variant range of input-parameter change. As regards the failure mode: the superior tensile properties of ECC led to the occurrence of a pull-out scheme rather than the anticipated splitting mode of failure. This diminished the role of cover thickness and stirrups, in this regards. Finally, new models are developed to predict the bond-slip behavior for ECC-to-steel rebar. The developed models demonstrated adequate agreement with experimental results.
•ECC is a novel material that attains superior behavior.•Bond behavior between ECC and RFT is main factor that affects element behavior.•The proposed models provide good prediction for bond strength.
Nowadays, wireless power transfer (WPT) has attracted great attention from researchers because it is a safe, convenient, and reliable way to recharge electric vehicles. Square and circular coils are ...most commonly used in WPT systems. However, there are few analyses of comparing these two geometry windings in detail. In this paper, two analytical models of both square and circular planar spiral coils between two semi-infinite substrates are developed based on Fourier-Bessel transformation and dual Fourier transformation. An analytical calculation of the selfand mutual inductance can be carried out with respect to the main parameters of the WPT systems such as the line spacing, the number of turns of the coils and the properties of the substrate. The analytical models can be used to investigate the different tendencies of selfand mutual inductance of square and circular coils, which is helpful for speeding up the design process. Finally, to compare the lateral misalignment tolerance between square and circular coils, a 600 mm × 600 mm with a nominal 200-mm-gap prototype has been built and tested.
Wireless power transfer (WPT) has attracted much attention in recent years. In an underwater WPT system, the eddy current loss tends to be non-negligible as the frequency or the coil current ...increases. Thus, it is crucial to analyze the eddy current loss in an underwater WPT system. The analytical model of the eddy current loss of a coreless WPT system in the seawater is established with Maxwell's equations. The expressions of the electric field intensity and the eddy current loss are derived. The eddy current loss is analyzed in different circumstances to illustrate the impacts of related factors. For a WPT system in the air, there is an optimum resonant frequency, for a higher frequency leads to a larger induced voltage, but will result in larger coil losses simultaneously. However, the optimum resonant frequency will be shifted because of the eddy current loss in the seawater. Then, the optimum operating frequency is obtained based on the analytical model. It is found that the optimum operating frequency is supposed to be larger than the resonant frequency to achieve the maximum dc-dc efficiency in the seawater. An underwater WPT prototype was built and the experimental results verified the theoretical analysis.
Cyber-physical system (CPS) is a new trend in the Internet-of-Things related research works, where physical systems act as the sensors to collect real-world information and communicate them to the ...computation modules (i.e. cyber layer), which further analyze and notify the findings to the corresponding physical systems through a feedback loop. Contemporary researchers recommend integrating cloud technologies in the CPS cyber layer to ensure the scalability of storage, computation, and cross domain communication capabilities. Though there exist a few descriptive models of the cloud-based CPS architecture, it is important to analytically describe the key CPS properties: computation, control, and communication. In this paper, we present a digital twin architecture reference model for the cloud-based CPS, C2PS, where we analytically describe the key properties of the C2PS. The model helps in identifying various degrees of basic and hybrid computation-interaction modes in this paradigm. We have designed C2PS smart interaction controller using a Bayesian belief network, so that the system dynamically considers current contexts. The composition of fuzzy rule base with the Bayes network further enables the system with reconfiguration capability. We also describe analytically, how C2PS subsystem communications can generate even more complex system-of-systems. Later, we present a telematics-based prototype driving assistance application for the vehicular domain of C2PS, VCPS, to demonstrate the efficacy of the architecture reference model.
Building efficient embedded deep learning systems requires a tight co-design between DNN algorithms, hardware, and algorithm-to-hardware mapping, a.k.a. dataflow. However, owing to the large joint ...design space, finding an optimal solution through physical implementation becomes infeasible. To tackle this problem, several design space exploration (DSE) frameworks have emerged recently, yet they either suffer from long runtimes or a limited exploration space. This article introduces ZigZag, a rapid DSE framework for DNN accelerator architecture and mapping. ZigZag extends the common DSE with uneven mapping opportunities and smart mapping search strategies. Uneven mapping decouples operands (W/I/O), memory hierarchy, and mappings (temporal/spatial), opening up a whole new space for DSE, and thus better design points are found by ZigZag compared to other SotAs. For this, ZigZag uses an enhanced nested-for-loop format as a uniform representation to integrate algorithm, accelerator, and algorithm-to-accelerator mapping. ZigZag consists of three key components: 1) an analytical energy-performance-area Hardware Cost Estimator, 2) two Mapping Search Engines that support spatial and temporal even/uneven mapping search, and 3) an Architecture Generator that auto-explores the wide memory hierarchy design space. Benchmarking experiments against published works, in-house accelerator, and existing DSE frameworks, together with three case studies, show the reliability and capability of ZigZag. Up to 64 percent more energy-efficient solutions are found compared to other SotAs, due to ZigZag's uneven mapping capabilities.
With high reliability and good cost-performance ratio, Si SJMOS and SiC SBD pair is often preferred in commercial single-phase PFC applications. Switching dynamics of Si SJMOS is different compared ...to 650<inline-formula><tex-math notation="LaTeX">\,</tex-math></inline-formula>V wide bandgap devices due to differences in device characteristics. This paper presents an improved analytical model to study the switching dynamics of Si SJMOS and SiC SBD pair. Unlike the existing literature on high-voltage Si MOSFETs, this paper considers the nonlinearities in channel current and internal capacitances of Si SJMOS, the nonlinear reverse-biased capacitance of SiC SBD, along with parasitic gate-drain capacitance arising due to PCB layout. As a result, the proposed analytical model presents a significant improvement over the existing models of high-voltage Si MOSFET in predicting switching loss, time, <inline-formula><tex-math notation="LaTeX">(dv/dt</tex-math></inline-formula>), <inline-formula><tex-math notation="LaTeX">(di/dt)</tex-math></inline-formula>, etc. Experimental and simulation results for three 650V Si SJMOS and SiC SBD pairs with different current ratings provide validation of the proposed analytical model.
•Global Interception Model (GIM) is a modified version of the sparse Gash model.•We developed linear regression models for global estimates of c and Sv parameters.•The new c and Sv models used remote ...sensing data and exhibited high performance.•GIM outperforms existing global products (PMLv2 and GLEAMv3.7a)
Accurate estimates of rainfall interception loss are crucial for modeling the water balance of forested areas. However, considerable regional variability exists in the interception process, and much uncertainty remains. This study enhances the estimation of rainfall interception loss at the global scale by integrating remote sensing products into the parameterization of Gash’s analytical model. We refer to this enhanced configuration as the Global Interception Model (GIM). High-resolution satellite imagery was used to derive vegetation indices and spectral reflectance, which were then employed in linear regression models to estimate canopy cover fraction (c) and vegetation water storage capacity (Sv). Their importance in ecological processes, and land and water resource management, makes the modeling of these parameters of particular interest. The other two parameters required to run the Gash model, namely the mean rainfall and evaporation rates under saturated canopy conditions, were obtained via the integration of MWSEP and ERA5-Land meteorological products. Modeling performance was evaluated using in situ measurements and gridded datasets. GIM estimates exhibited a superior performance statistic when compared to PMLv2 and GLEAMv3.7a. Our results demonstrate the high potential of this approach for improving the accuracy of rainfall interception loss estimates from local to global scales.
Integrating more accurate models for battery aging into dispatch optimization can help enhance the economic performance of battery systems. To this end, this paper proposes an analytical ...Rainflow-based cyclic aging model that accounts for the cycle depth and average state of charge (SoC) stress factors, particularly crucial for batteries that experience irregular cycling patterns under complex market conditions. As a function of the battery SoC time series, the aging model is compatible with a mixed integer linear programming (MILP) formulation, enabling the dispatch problem to be solvable by commercial solvers. The flexibility of the model enables decision-makers to fine-tune its specific expressions, creating variants that balance model accuracy with solution efficiency. A lightweight dispatch optimization framework and a convex variant of the aging model are developed for batteries participating in a pay-for-performance frequency regulation market to reduce problem-solving time significantly. Validated on two batteries with different aging characteristics, the proposed model shows high prediction accuracy, with an average error of less than 5%. Case studies employing full-year historical market data from ISO New England (ISO-NE) and PJM validate the effectiveness and reliability of the proposed methods in enhancing battery economics for price arbitrage and frequency regulation tasks.
In this paper, a 2-D analytical electromagnetic model based on separation of variables method (SVM) is proposed for spoke type interior permanent magnet slotless machines. The novelties and ...contributions consist of: 1) considering the finite permeability of inter-pole irons of the rotor and 2) considering the rotor as a single composite subdomain. In addition, the structure is reduced to 1/ p or 0.5/ p where p is the number of poles, because of the possibility of anti-periodic and symmetric field distribution. The proposed model is effective both in terms of preprocessing formulation and computational burden. It is shown that the motor quantity calculations will solely require the magnetic vector potential which is directly obtained from SVM formulation. The results of the proposed analytical model are compared with those of the finite element method showing the accuracy and effectiveness of the proposed model.
In this paper, the end forces caused by the longitude end effects in linear permanent magnet synchronous machines (LPMSMs) are analyzed and minimized. First, the left/right-end forces are calculated ...based on an analytical model and the Maxwell stress tensor, in which the optimal integration surfaces are investigated. Then, based on the spectrum analysis of the left/right-end forces, two different methods are adopted to minimize the fundamental and high-order harmonics, respectively. The optimal length of the primary iron is obtained from the phase difference of the fundamental and a two-step iteration instead of the trial-and-error with the finite element method. Furthermore, step-skewed auxiliary irons are added to the primary end to eliminate the high-order harmonics. Third, to reduce the secondary end effect when the primary moves to the secondary end, a compensation method of adding mirror permanent magnet is proposed and good results are obtained. Finally, an LPMSM prototype is manufactured and experiments are conducted. The experimental results verify the theoretical study.
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