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This paper presents an effective design of an array of coupling slots with reflection-canceling walls for uniform excitation of a parallel-plate slot array antenna panel. The coupling slot array is analyzed by Galerkin’s method of moments (MoM) for the fast design by simplifying to use only uniform current on the reflection-canceling walls. It takes only 20 seconds to analyze an array of 14 coupling slots by MoM by a laptop PC having a 16-core Intel Core i7 CPU with 2.60GHz base frequency and 16 GB RAM while it takes 4 hours by HFSS. The values of parameters of each coupling slot by MoM are replaced with those by HFSS having the equal scattering matrix components.

In this study, a post-treatment method was carried out to increase the tensile strength of poly ether ketone (PEEK) fibers, with a maximum increase of 69%. The effects of the post-treatment process parameters on the diameter shrinkage ratio, mechanical properties of PEEK fibers, and the aggregated state structure were also quantitatively investigated by optical measurements, uniaxial tensile tests, differential scanning calorimetry, and two-dimensional-wide angle X-ray diffraction. These studies revealed that the enhanced orientation of PEEK fibers with increasing post-treatment temperature and constant tensile force is the major reason for the significant increase in uniaxial tensile strength. The diameter shrinkage ratio can be used as an indicator of the degree of fiber orientation. More critically, this study also presented mathematical models that described the high linearity of the increase in diameter shrinkage ratio and uniaxial tensile strength of fibers with post-treatment temperature and constant tensile force, respectively. That also revealed the equivalence of temperature and constant tensile force in the post-treatment process and obtained the conversion factor. These in-depth understandings provided positive guidance for improving the strength of PEEK fibers and achieving controllable morphology and mechanical properties in PEEK fiber production.

The equivalent relationships between flood prevention storage of a cascade reservoir system provide useful information for real-time operation. However, those relationships are implicitly hinted at in the optimized operation rules of downstream reservoirs, which may add difficultly in providing feasible operation strategies for engineering practice. In this study, we investigate the equivalent relationship between cascade reservoirs using a flood regional composition-based framework coupled with reservoir inflow and river flow routing techniques. We select the cascade reservoirs in the downstream Jinsha River and Three Gorges Reservoir (TGR) as the case study. Results reveal that (1) the equivalent relationship between flood prevention storage of cascade reservoirs in the downstream Jinsha River and TGR is approximately linear-related; (2) the conversion coefficient of equivalent relationship depends on the flood type, and the intercept term of equivalent relationship is mainly influenced by the design flood frequency; and (3) the TGR flood prevention storage (or water level) can be dynamically adjusted according to the corresponding reserved flood prevention storage of cascade reservoirs in the downstream Jinsha River, which can generate 3.56 billion kW·h (+8.5%) extra hydropower during flood season without increasing flood control risks. [ABSTRACT FROM AUTHOR]

In order to achieve equivalent modulation of the multilevel current converter, based on the topology of three-phase multilevel current-source converters, this article presents a method to realize the output characteristic of space vector pulsewidth modulation (SVPWM) with carrier-based PWM, which can be applied in the topologies from five-level to n-level space vector modulation strategy. Different from the strategies of traditional unity theory, the proposed method analyzes the relationship directly according to the switching states of SVPWM in three-phase multilevel current-source converters. By constructing the equivalent relationship between the output level of each phase and switching states, the carriers can control the working status of the switches directly. In addition, this method is generalized to the topologies and modulation strategies under n-level, which fully reflects the correctness and universality of the proposed method. Finally, the results of simulation and experiment verify the correction of the method. [ABSTRACT FROM AUTHOR]

The weathering aging pattern is a time-consuming aging method although it is accessible to asphalt actual field aging conditions. The accelerated ultraviolet (UV) radiation aging in laboratory shows the same aging factors (such as heat, oxygen and UV radiation) as weathering aging, which can make the accelerated UV radiation aging in laboratory become a potential alternative to weathering aging. Therefore, it is necessary to build the equivalent relationship between these two aging patterns and then to shorten the required weathering aging durations by accelerated UV radiation aging simulation. Two types of base asphalt binder were selected as research objects and the evolution of their rheological properties including complex modulus (G*), phase angle (d) and zero shear viscosity (ZSV) with indoor accelerated UV radiation aging durations was investigated. Then, based on logarithmic zero shear viscosity (log (ZSV)) values, the relationship between accelerated UV radiation aging and weathering aging of asphalt binder was built by utilization of two-reaction kinetic aging model and extrapolation of accelerated aging result to weathering aging result. Furthermore, the equivalent relationship between the two aging patterns was further validated in terms of molecular weight distribution and carbonyl index results. The results indicate that with the increase in accelerated UV aging time, values of complex modulus and zero shear viscosity gradually increase whereas values of phase angle decrease for both two base asphalt binders. The changing trend of log (ZSV) value with UV aging time fits well with two-reaction kinetic aging model. The 18-month weathering aging is demonstrated to be almost equivalent to 16~18-day accelerated UV aging by analyzing rheological, molecular weight distribution and carbonyl index results. [ABSTRACT FROM AUTHOR]

In this paper, silicone rubber on composite insulators from three different manufacturers with an operating duration between 1 and 10 years were sampled. In order to investigate the law of diminishing performance of these samples in aging process, widely adopted aging process evaluation test methods such as Hydrophobicity test, Water absorption test were performed. Based on test results, parameters significantly correlated with operating time were obtained by means of correlation calculation. Finally, considering the differences of parameter values among three manufacturers, the relative decrease value (denoted as w) of parameters was proposed as a unified standard and the equivalent equations between w and operating time were established for predicting lifespan of composite insulators in high altitude area. Test results indicate that parameters including saturated water absorption ratio δs, the relative content of Si and O elements (XSi and XO) are significantly correlated with operating time, and these three parameters can be used to characterize aging degree of composite insulators. Besides, for the relative error σ1 between theoretical operating time calculated by the equivalent relationship obtained in this paper and actual operating time is less than 20%, within the allowable error range of engineering practice, this equation can be applied to predict the operating time of composite insulators from three manufacturers in future research.

In order to solve the problem that the equivalent relationship between space vector pulse width modulation ( SVPWM) and carrier-based pulse width modulation ( CBPWM) in the field of single phase multi-level inverters is still unclear， this paper drew on the equivalent realization method of three-phase multi-level inverters． And the equivalent relationship between the two modulation strategies of SVPWM and CBPWM was studied in depth according to the characteristics of the multilevel single phase diode clamped inverter． By injecting the deduced DC component into the CBPWM modulated wave ，the same modulation output sequence as SVPWM was obtained， and by further strictly derived ，the DC component formula realizing the equivalent of any number segment SVPWM sequences and CBPWM was obtained under single phase NPC n-level inverters． Finally， the experiment verifies correctness of the equivalent relationship． [ABSTRACT FROM AUTHOR]

Loading spectrum statistic acquired from proving ground has great effect on the component fatigue life prediction.a fatigue damage and life prediction method based on the acceleration signal was put forward,this method is applied to engine mount bolt whose loading spectrum can’t be directly acquired in working condition. First,by macrofracture observation and mechanical model analysis,the relationship between the main stress load and acceleration load of different condition was defined.Then according to the S-N curve of engine mount bolt,and applying the acceleration signal in different working condition,bending moment and tensile stress in time series was calculated. The engine mount bolt fatigue damage was figured out based on those time series. Finally,by compearing with the fatigue life of two measured roads,the equivalent relationship between the two roads is established.

Isooctane is often used as a substitute to investigate the heat release, chemical kinetic models and flame behaviors of the gasoline vapor explosion process. Such substitution always leads to some inevitable errors between the overpressures of theoretical calculation value and the experimental data of the gasoline vapor explosion. Based on the deduction of the relationship between the equivalence ratio (∅ ) and volume concentration of isooctane–air mixture, the constant volume adiabatic combustion temperature and overpressure of the isooctane explosion at different ∅ were calculated by using the first law of thermodynamics. Then, through the experiments of gasoline vapor explosion in a standard 20-L spherical explosive device, explosion overpressures at different gasoline vapor volume concentrations were obtained. By analyzing the overpressure error between the theoretical value of the isooctane explosion and the experimental data of the gasoline vapor explosion, an equivalent relationship in terms of isooctane equivalence ratio for gasoline vapor constant volume explosion overpressure is proposed. This relationship not only can be used to accurately predict gasoline vapor constant volume explosion overpressure by means of isooctane, but also can be used to modify the gasoline explosion overpressure calculation model and enable the errors between the model's calculation value and the actual experimental value to be significantly reduced. [ABSTRACT FROM AUTHOR]

The impulse voltage wave invading a transformer is not the double exponential impulse wave (DEIW) specified by the IEC but a non‐standard waveform with oscillation attenuation characteristics, and this fact leads to doubts about the scientificity and optimality of insulation coordination. A key solution for this issue is the establishment of an equivalent relationship between the measured non‐standard impulse voltage wave and the DEIW. In this study, a test platform of multiparameter impulse voltage was set up. Then, the authors obtained the 50% breakdown voltage (U50%) of the oil‐impregnated paper (OIP) for transformer under the bipolar oscillatory attenuated impulse wave (BOAIW) and the DEIW with different waveform parameters. The effects of waveform parameters on the breakdown characteristics of the OIP were finally revealed. On the basis of experimental data and several mathematical methods, the authors established the U50% prediction mathematical models for the OIP under the BOAIW and DEIW. Based on the prediction models and the microfluctuation characteristics of measured overvoltage's waveform parameters, the authors proposed a method for evaluating the waveform equivalence. The characteristics of voltage amplitude and change rate were regarded as the two key factors for the waveform equivalence of this method. [ABSTRACT FROM AUTHOR]

Rectangular concrete-filled steel tubes (CFSTs) have been widely employed as prominent structural members in modern constructions. During their life cycles, rectangular CFST members may suffer from impact loads, leading to a need for investigations into their dynamic performance. In this context, 23 rectangular CFSTs subjected to transverse impact loading were experimentally investigated using a drop weight testing system. The instantaneous impact force responses and motion states of the specimens were recorded at high frequencies. The aspect ratio, the steel ratio and the clear span of the specimen, as well as the impact energy conditions, were the key parameters in the test scheme, and their influence on the dynamic response of the rectangular CFST specimens was analyzed. A finite element (FE) model was developed to predict the impact response of rectangular CFSTs, in which the strain rate effects of steel and concrete were well considered, and good accuracy was achieved. Then, an equivalent relationship between rectangular and square CFSTs under transverse impact was proposed and verified, which achieves access for rectangular CFSTs to existing design methods. • The dynamic response of rectangular CFST columns under transverse impact was experimentally and numerically studied. • Coupling influence of the aspect ratio and the impact direction has been studied for rectangular CFSTs. • An equivalent relationship between rectangular and square CFSTs under transverse impact was proposed. [ABSTRACT FROM AUTHOR]

The traditional decision tree algorithms such as ID3 usually uses a single attribute as the basis of branching judgment.The scale of the tree generated by ID3 is very large and rules formed are difficult to understand.Aiming at the problems described above,an algorithm was proposed using multi-variable as the judging conditions of node attributes.By using the property of attribute dependency in rough set and choo-sing nuclear properties of condition attributes relative to decision attributes in the information system as multi-variable node attributes,the algorithm used the concept of relative generalization to aid the branching process and generated a multi-variable decision tree.Through the analysis of example and by comparing with the conventional ID3 algorithm,the high efficiency of the improved algorithm was verified. [ABSTRACT FROM AUTHOR]

Among algorithms for comparing the areas under two or more correlated receiver operating characteristic (ROC) curves, DeLong's algorithm is perhaps the most widely used one due to its simplicity of implementation in practice. Unfortunately, however, the time complexity of DeLong's algorithm is of quadratic order (the product of sample sizes), thus making it time-consuming and impractical when the sample sizes are large. Based on an equivalent relationship between the Heaviside function and mid-ranks of samples, we improve DeLong's algorithm by reducing the order of time complexity from quadratic down to linearithmic (the product of sample size and its logarithm). Monte Carlo simulations verify the computational efficiency of our algorithmic findings in this work. [ABSTRACT FROM AUTHOR]

The roller honeycomb feeding roller (RHFR) of forest harvester in logging was raised for reducing damage to logs. The equivalent relationship of roller double V-wings honeycomb (RDWH) were proposed and analytically derived in the mass, platform stress and elastic modulus. The finite element models of RDWH with various cell densities under the equivalent relation were established. The mechanical properties, energy absorption characteristics, impact response, structural stability, structure efficiency and improvement performance efficiency of RDWH under compression impact were investigated in comparison with roller hexagonal honeycomb (RHH). The RDWHs with equivalent relationship had approximate mechanical properties under unit compression displacement. The RDWH, benefiting from the NPR enhancement phenomenon in deformation, possessed about multiple times of mechanical properties and energy absorption efficiency than RHH. The performance efficiency of RDWH related to cell densities and cell layers in "PVP" and "Bunching Phase" trend. The RHFR exceeded that of the steel feeding roller (SFR) with about 2 times in maximum contact area under the corresponding contact force. The phenomenon of "sequential increment" and "uprush stage" appeared in contact area of RHFR for G i groups were recorded with relating of cell densities and cell layers, which provided significance on reducing damage to logs. [ABSTRACT FROM AUTHOR]