Comprehensive Evaluation Parameters Research Articles

Correlation between the initial aging of epoxy coatings and the typical marine atmospheric environmental factors

PurposeThe anticorrosion coatings used in marine and atmospheric environment are subjected to many environmental factors. And the aging failure has been puzzling researchers. The purpose of this study is to find the correlation between the initial aging of epoxy coatings and the typical marine atmospheric environmental factors.Design/methodology/approachThe epoxy coatings were subjected to a one-year exposure in three typical marine atmospheres. Meanwhile, principal component analysis, linear regression and Spearman and gray correlation analysis were applied to quantify the environmental characteristics and establish correlations with the coating aging.FindingsThe results indicate that the coating will undergo macroscopic fading and chalking upon exposure to the marine atmosphere, while microscopic examination reveals holes, cracks and partial peeling. The adhesion performance and electrochemical properties of the coating deteriorated with prolonged exposure, coating aging mainly occurs with the generation of O-H bonds and the breakage of molecular chains such as C-N and C-O-C. The coating was most deeply aged after exposure to the Xisha, followed by Zhoushan and finally Qingdao. Environmental factors affect the photooxidative aging and hydrolytic degradation processes of coatings and thus coating aging. To further demonstrate the correlation between environmental factors and coating aging, principal component analysis was used. The correlation model between environmental factors and coating aging was subsequently obtained. The correlation model between the rate of coating adhesion loss (E) and the comprehensive evaluation parameter of environmental factors (Z) is expressed as E = 0.142 + 0.028Z. Meanwhile, the Spearman correlation analysis and gray correlation method were used to investigate the impact of each environmental factor on coating aging. Solar irradiation, relative humidity and wetting time have the highest correlation with coating aging, which are all above 0.8 and have the greatest influence on coating aging; wind speed and temperature have the smallest correlation with coating aging, which are about 0.6 and have the least influence on coating aging.Originality/valueThis paper establishes a correlation between typical marine environmental factors and coating aging performance, which is crucial for predicting the service life of other coatings in diverse environments.

A High-Sensitivity Bimetallic Grating-Coupled Surface Plasmon Resonance Sensor Based on Two-Dimensional Materials

Optical biosensors based on grating-coupled surface plasmon resonance (GCSPR) technology are an important research topic in the field of bio-photonics. This paper presents a high-performance and high-sensitivity nanostructured bimetallic GCSPR sensor based on two-dimensional materials. When designing the sensor, the sensitivity, full width at half peak (FWHM) and dip strength of the absorption peak (DS) were considered comprehensively, and the comprehensive evaluation parameter FOM+ is defined by making improvements on the basis of figure of merit (FOM). The performance of the sensor can be judged more comprehensively. The performance of the sensor was further improved by optimizing the structure of the sensor. An ultra-thin gold layer was added on the surface of the silver-based GCSPR sensor, which solves the problem of the easy oxidation of silver metal. We tried to coat graphene oxide two-dimensional nanomaterials on the surface of the bimetallic sensor, and the sensitivity and FOM+ of the sensor reached 350 deg/RIU and 473.23, respectively. This is a great improvement compared with the GCSPR sensor in a previous study, and it can be improved at least 74.7%. This sensor can measure a variety of biological molecules and biological cells with high sensitivity and performance by detecting the change in the refractive index of the solution to be measured.

A Comprehensive Evaluation Method for Sensing Characteristics of Multi-Peak Terahertz Metamaterials Sensor in Polarization Mode

In this study, the multi-peak terahertz metamaterials sensors are designed and fabricated, whose structures are the asymmetrical single split ring (SSR) and three split rings (TSR). The resonant formation and sensing mechanism of the two structures are investigated by using the finite-difference time-domain (FDTD) method. Vitamin B6 (VB6) and its reactants with bovine serum protein (BSA) are tested as the medium, and the sensing experiments of the SSR and TSR are carried out. The experimental and simulation results indicate the consistent law, which is the sensitivity of the resonance in the transverse magnetic (TM) mode is much greater than that in the transverse electric (TE) mode. According to the weighted average method and the law for unequal precision measuring, the quality factor of the resonance is used as the weighting coefficient to calculate the comprehensive evaluation parameter (CEP) of the multi-peak metamaterials sensors in the TE and TM modes based on the experimental data. When the CEP and frequency shifts are as the evaluation parameter in experiments, the law’s variation of the CEP is consistent with that of the frequency shift, indicating that it is feasible to characterize the sensing characteristics of metamaterials with the CEP, which presents simplified characteristics of multi-peak metamaterials at different polarization modes. The method implies that the different influencing factors may be integrated into the CEP with the idea of weight, which promotes the practical application of the metamaterials sensor. The revelation of the sensing law also provides a method for the design of the terahertz metamaterials sensor with the high sensitivity.

P‐12.7: Front Light Guide Plates for Reflective LCDs

Reflective liquid crystal display has the advantages of energy saving and environmental protection. When the ambient light is low, the front light source is required to provide illumination rays. The front light guide plate has a great influence on display luminance, contrast, etc. Based on Comprehensive considerations on luminance, uniformity, stray light, an analysis and evaluation method for front light guide source is proposed. Taking spherical dots as an example, the influence of dot radius and height on the comprehensive performance of the front light source is analyzed. The simulation results show that when the R:H is 3:1, the comprehensive evaluation parameters of the spherical structure are high, and the signal‐to‐noise ratio is increased by 240%, which can greatly improve the display performance. The analysis and evaluation method proposed in this paper can effectively guide the development of front light guide plates, shorten the development time and reduce the development cost.

Theoretical framework, indicator system and practical application of key biodiversity areas.

With the continuous decline of global biodiversity, biodiversity conservation has attracted more and more attention from the international society. In order to slow down the trend of biodiversity decline, it is particularly important to identify key areas for biodiversity conservation. However, most of current methods for identifying important areas have different assessment criteria and focus on different biological assemblages (species or communities) and ecosystem types. Key biodiversity areas (KBAs) are sites that contribute significantly to global biodiversity persistence. Unlike traditional research and identification methods, KBAs identification is based on a unified global standard to explore habitats that are critical to endangered plants and animals in terrestrial, freshwater, and marine ecosystems. Based on the theoretical and technical framework of KBAs, we summarized the system of identification criteria and assessment parameters for KBAs. The five high-level criteria are separated into eleven sub-level criteria. Among the eleven evaluation parameters, there is one evaluation parameter for the ecosystem level, eight evaluation parameters for the species level, one evaluation parameter for the gene level, and one comprehensive evaluation parameter. In addition, we analyzed the application of KBAs identification in biodiversity research and conservation combined with relevant domestic and foreign research cases. Furthermore, we discussed the future development direction and application prospect of KBAs identification method in China. This method could provide a new perspective for the formulation of ecological protection policies and the planning of naturally protected areas in China.

Principle and performance optimization analysis of a frost-free control for electric vehicle heat pumps

To avoid the attenuation of the electric vehicle driving range caused by the performance degradation of the heat pump during frost, a frost-free control strategy was developed which enables frost-free operation without adding any additional dehumidifying and drying components. Simulation analyses of the frost-free control principle and performance characteristics are carried out. Thermodynamic and response characteristics of evaporation temperature to valve openings of different heat pumps are compared. The results show that excessive pressure drops in evaporators severely hinder the realization of frost-free operation. Then, the effect of evaporator designs on frost-free operation is further investigated. A new comprehensive evaluation parameter (η) that can unify pressure drop and heat transfer is proposed. When η is between 0 and −2, the heat exchanger meets the requirements of frost-free control. In addition, the upper humidity range for frost-free operation at different temperatures is calibrated. When the ambient temperature is 0/-5/-10/-15/-25 °C, the corresponding maximum humidity that can achieve frost-free operation is 87/86/85/84/82 %, respectively. In low temperature and high humidity regions, the frost-free operation can be guaranteed by increasing the evaporator airflow volume rate and reducing the supply air temperature.

Aging State of Stator Bar Insulation Based on the Entropy Weight and Dielectric Response Methods

This article describes a novel research method for evaluating the aging state of the primary insulation material of large generator stator bars based on combining dielectric response methods with the entropy weight method. Vacuum pressure impregnation (VPI) epoxy-mica insulation specimens subjected to different electrical aging time periods were characterized via frequency domain spectroscopy (FDS), polarization and depolarization current (PDC), and thermal stimulated depolarization current (TSDC) tests. The comprehensive characteristic (VPI) parameters obtained by calculating the characteristic dielectric response parameters using the entropy weight method were used to describe the aging state of the VPI epoxy-mica insulation. The results show that during electrical aging, microcosmic structural variations within the insulation directly manifested as changes in the characteristic dielectric response parameters and indirectly affected the comprehensive evaluation parameters of the entropy weight method.

Analysis of the Influence of Waste Seashell as Modified Materials on Asphalt Pavement Performance.

An increasing amount of waste seashells in China has caused serious environmental pollution and resource waste. This paper aims to solve these problems by using waste seashells as modified materials to prepare high-performance modified asphalt. In this study, seashell powder (SP) and stratum corneum-exfoliated seashell powder (SCESP) were adopted to prepare 10%, 20% and 30% of seashell powder-modified asphalt (SPMA) and stratum corneum-exfoliated seashell powder-modified asphalt (SCESPMA) by the high-speed shear apparatus, respectively. The appearance and composition of two kinds of SPs were observed and determined by the scanning electron microscope (SEM). The types of functional groups, temperature frequency characteristics, low temperature performance and adhesion of SPMA were tested by the Fourier-transform infrared (FTIR) spectrometer, dynamic shear rheometer (DSR), bending beam rheometer (BBR) and contact angle meter. The results show that the SP and SCESP are rough and porous, and their main component is CaCO3, which is physically miscible to asphalt. When the loading frequency ranges from 0.1 Hz to 10 Hz, the complex shear modulus (G*) and phase angle (δ) of SPMA and SCESPMA increase and decrease, respectively. At the same load frequency, SCESPMA has a larger G* and a smaller δ than SPMA. At the same temperature, SCESPMA has a larger rutting factor (G*/sin δ) and better high-temperature deformation resistance than SPMA. SP and SCESP reduce the low-temperature cracking resistance of asphalt, of which SCESP has a more adverse effect on the low-temperature performance of asphalt than SP. When SP and SCESP are mixed with asphalt, the cohesion work (Waa), adhesion work (Was) and comprehensive evaluation parameters of water stability (ER1, ER2 and ER3) of asphalt are improved. It is shown that both SP and SCESP have good water damage resistance, of which SCESP has better water damage resistance than SP. These research results have important reference value for the application of waste biological materials in asphalt pavement.

Vibration and damping performance of carbon fiber-reinforced polymer 3D double-arrow-head auxetic metamaterials

The vibration and damping performances of carbon fiber-reinforced polymer (CFRP) three-dimensional double-arrow-head (3D DAH) auxetic metamaterials are investigated in this paper. The negative Poisson’s ratio effects of the CFRP 3D DAH auxetic metamaterials are analytically studied by the energy method. 3D finite element models based on Modal Strain Energy approach are developed to analyze their vibration and damping characteristics. To validate the numerical models in the present study, the CFRP 3D DAH auxetic metamaterials are designed and manufactured. The sine-sweep response tests are conducted to investigate their vibration performances. The influence of different inclined corrugated angles, and fiber orientations on the natural frequencies, loss factors and the nominal Young’s modulus are plotted and discussed using validated numerical models. Meanwhile, the effect of Poisson’s ratio on the nominal Young’s modulus, natural frequencies and loss factors is also revealed explicitly. Furthermore, the comprehensive evaluation parameter that simultaneously characterizes the structural bearing capacity and vibration damping performance is further improved through parameter optimization.

A new method for evaluating the effectiveness of hydraulic fracturing in tight reservoirs

The effectiveness of hydraulic fracturing in tight reservoirs is considered to be influenced by three main factors, namely, stimulated reservoir volume (SRV), fracture density, and fracture conductivity. No conclusive method is available to predict the effectiveness of hydraulic fracturing; there is often a failure to determine whether production differences among wells are caused by the effectiveness of the hydraulic fracturing or by the geological conditions, fluid properties, and other factors. Based on the principles of energy conservation and material balance, a mathematical model for calculating the average length of fractures and hypothetical number of fractures was established by the calculus of variations to obtain the key parameters for describing fracture density and conductivity. The degree of influence of the individual parameters on the effectiveness of hydraulic fracturing is obtained from Grey correlation analysis, and two calculation models for the comprehensive evaluation parameter are proposed. The comprehensive evaluation parameters produced from the two models have a preferable correlation with the well production. This paper presents a rigorous method for evaluating the effectiveness of hydraulic fracturing, which can explain the reasons for the production differences between wells.

Heat Transfer Properties of a Latent Thermal Storage Unit with Flat Microheat Pipe Arrays

AbstractA thermal storage unit (TSU) with flat microheat pipe arrays (FMHPAs) as heat transfer core is experimentally investigated in this study. A comprehensive evaluation parameter of the TSU def...

Experimental research on intermittent heat pump drying with constant and time-variant intermittency ratio

ABSTRACTThe aim of this article was to estimate the effectiveness of intermittent drying with constant and time-variant intermittency ratio, compared with continuous drying. Intermittent drying was accomplished by periodically changing the heat input and air velocity. To achieve accurate control of drying temperature, a new parallel conversion controller was used. Based on the well-controlled heat pump drying system, the drying kinetics of green soybean were analyzed using seven intermittent drying profiles. The increase of intermittency ratio caused decrease of effective drying time and increase of specific moisture extraction rate (SMER). SMERs of intermittent drying were 1.21–4.94 and 0.93–5.40 times more than the continuous drying for different initial moisture content (23 and 28%), respectively. Changes of drying rate (DR) and SMER became relatively moderate when intermittent drying with time-variant intermittency ratio was used. A comprehensive evaluation parameter, based on DR and SMER, was proposed and calculated. Experimental results indicated that intermittent drying (α = 5/6) and intermittency drying with time-variant ratio gave the best two comprehensive performances.

Geochemical and eco-toxicological characteristics of stream water and its sediments affected by acid mine drainage

In assessing the adverse effects of acid mine drainage (AMD), the chemistry of AMD and stream water (i.e., pH and toxic metal concentrations) has been accounted as important monitoring parameters and its characteristics are regulated in many countries. Yet for the precise evaluation of eco-toxicological effect on AMD receiving streams, a more comprehensive evaluation parameter has to be recognized as a mandatory parameter. In this study, eco-toxicological correlations between chemical properties of water and sediments collected from an AMD receiving stream were investigated at an abandoned mine site in Korea. The stream water in the AMD watercourse near the mine adit that is highly acidic and contains high concentrations of heavy metals, has been neutralized as the AMD became diluted with nearby natural stream water. The toxicity of stream water showed a relatively strong correlation with the pH and dissolved metal concentrations of water implying the toxic effects of stream water on its stream biota. In contrast, the toxicity results obtained from stream sediments hardly showed close correlation with the composition of toxic elements, particularly with enriched arsenic.

Comprehensive Evaluation for Putaohua Reservoir in Sanzhao Depression

With complicated geological background, Putaohua reservoir in Sanzhao depression has lots of blocks. Based on its distribution characteristics and evaluation unit division as well as combined with detailed geological characteristics, parameters of developed and undeveloped blocks were optimized and the comprehensive evaluation parameters were determined. In order to make a correct evaluation for oil content, oil distribution, reservoir physical properties and productivity, this paper has adopted comprehensive quantitative evaluation method to do the comprehensive classification and evaluation for developed and undeveloped blocks. It can not only further improve oil recovery of developed blocks but also provide scientific basis for selecting favorable blocks for productivity construction of undeveloped blocks. According to the classification standard, the developed and undeveloped blocks of Putaohua reservoir in Sanzhao depression were separately divided into three types including Class Ⅰ, Ⅱand Ⅲ. In view of the geology and development factors, undeveloped blocks of Class Ⅰ are equivalent to developed blocks of Class Ⅱ; undeveloped blocks of Class Ⅱ are equivalent to developed blocks of Class Ⅲ; undeveloped blocks of Class Ⅲ are the poorest of all.