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Passenger ships are likely to be inclined during and after accidents, which is a vital factor that affects pedestrian behaviors and crowd dynamics in the evacuation process. On a significantly inclined ship, pedestrian fall behavior becomes more complex, increasing the risk of stampedes. Nevertheless, this type of evacuation has rarely been investigated. In this study, an extended cellular automata (CA) model that meets the inherent characteristics of passenger ship evacuations is constructed. The inclination force and self-adjusting force are incorporated into the model to evaluate the balance mechanism of pedestrians, while a method to calculate the probability of pedestrians falling down is established by considering the ship heeling angle and pedestrian heterogeneity. Further, the state of the pedestrians after falling to the ground is analyzed. A hazard field is introduced to describe the interaction between normal pedestrians and fallen pedestrians. The simulation results show that deaths occur when the ship heeling angle is greater than 20° and the crowd is evacuated successfully and fastest at the ship heeling angle of 5°, even better than on the flat ground. The greater the ship heeling angle, the more likely pedestrians are to fall over, and the earlier the first death occurs, thereby resulting in longer evacuation time and increased fatalities. The heterogeneity of passengers has considerable effects on the effectiveness of the ship evacuation, with a greater proportion of strong-resistance pedestrians reducing the crowd death and fall risks, even though the influence of crowd constitution on crowd evacuation time is insignificant. The death toll and evacuation time increased with the initial number of pedestrians aboard the ship. This study is beneficial in terms of understanding the evolution mechanism of evacuation dynamics and developing effective strategies for crowd emergency management on large passenger vessels. • An improved CA model for ship evacuation is constructed considering ship inclination and pedestrian fall behavior. • A method to describe balancing mechanism of pedestrians and to calculate the probability of pedestrian falling over is proposed. • Influences of ship inclination angles, crowd-constitute and initial pedestrian numbers on pedestrian fall numbers, pedestrian fatality and evacuation efficiency are discussed based on the improved model. • This study provides useful insights for emergency decision-making and risk management for large crowd in passenger vessels. [ABSTRACT FROM AUTHOR]

The low-resolution characteristic of Gravity Recovery and Climate Experiment (GRACE) satellite data greatly limits their application in many fields at regional or local scales. Aiming to overcome this limitation, the partial least squares regression (PLSR) model is firstly utilized to assess the importance of some independent variables that are commonly employed in GRACE downscaling research. Three kinds of downscaling models are chosen to improve the resolution of GRACE-based water storage estimates from 1 to 0.25°, namely: multivariable linear regression, random forest (RF), and NoahV2.1. Results indicate that terrestrial water storage anomalies are more closely related to four independent variables in the Haihe River Basin, China: these variables are evapotranspiration, land surface temperature, air temperature, and soil moisture. With respect to the spatial distribution, the downscaled results based on the NoahV2.1 and RF models can effectively capture the subgrid heterogeneity while preserving the water storage characteristics at the original scale. By verifying the downscaled results with measured groundwater levels, it can be observed that the correlation coefficient between the RF-based downscaled groundwater storage anomalies (GWSA) and in-situ measurements is increased by 20.55% (Beijing), 9.13% (Tianjin), and 10.48% (Hebei) relative to the downscaled results based on the NoahV2.1 model. The cross wavelet transform illustrates that the meteorological factors have a strong influence on the GWSA series in the Haihe River Basin with an approximately 12-month signal during 2003–2016. This study can provide high-resolution GWSA datasets for water resources management and also provide a reference for the selection of dominant independent variables. [ABSTRACT FROM AUTHOR]

An information system (IS) is an important model in rough set theory. In practice applications, we often encounter an IS with different structures of information values. A three heterogeneous information system (3HIS) means an IS whose information values contain three types of data (i.e., scaled types, ordered types and normal types). This paper studies uncertainty measurement for a 3HIS and its application in feature selection. A 3HIS is first put forward. Then, the fuzzy relation on the object set with respect to each subsystem is defined. Next, four measure tools are used to assess the uncertainty of a 3HIS according to the fuzzy information granules induced by the defined fuzzy relation. Combining with the proposed measures, an application for feature selection in a 3HIS is given, and the corresponding algorithms based on the uncertainty measures are presented. Finally, numerical experiments are carried out and effectiveness analysis from the statistics perspective is done as so to evaluate the performance of the presented algorithms. The experimental results indicate that the proposed algorithm is more effective than some existing algorithms. These results will contribute to understanding the essence of uncertainty in a 3HIS. [ABSTRACT FROM AUTHOR]

An information system as a database that stands for relationships between objects and attributes is an important mathematical model. An image information system is an information system where each of its information values is an image and its information structures embody internal features of this type of information system. Uncertainty measurement is an effective tool for evaluation. This paper explores measures of uncertainty for an information system by using the proposed information structures. The distance between two objects in an image information system is first given. After that, the fuzzy Tcos-equivalence relation, induced by this system by using Gaussian kernel method, is obtained, where Gaussian kernel is based on this distance. Next, information structures of this system are described by set vectors, dependence between information structures is studied and properties of information structures are given by using inclusion degree, and application for information structures and uncertainty measures of an image information system are investigated by the information structures. Moreover, effectiveness analysis is done to show the feasibility of the proposed measures from the angle of statistics. Finally, an application of the proposed measurement for attribute reduction is given. These results will be helpful for understanding the essence of uncertainty in an image information system. [ABSTRACT FROM AUTHOR]

Ti 6Al 4V alloy is promising material as biomedical micro/nano–electromechanical systems. However, its poor microtribological properties have a negative impact on the micromachine stability. In this study, enhancements in anticorrosion and microtribological performances under dry and SBF lubrication are realized by grafting graphene oxide (GO) on the alloy surface. We further demonstrate that based on a 3-aminopropyltriethoxysilane (APTES) transition layer, the GO-coated sample with dopamine (DA) adhesive layer (APTES-DA-GO) exhibits better properties than those of the APTES-GO. Moreover, the anticorrosion and tribological mechanisms of the GO-coated samples were discussed. Analyses of worn surfaces show that the relative slip of GO sheets and entrapment of wear particles of the surface topography are the main factors contributing to the improved tribological behaviour. Image 1 • Multilayer graphene oxide (GO) coatings are assembled on the Ti 6Al 4V alloys. • Dopamine is selected as the adhesive layer in the self-assembly technology. • Ti 6Al 4V coated GOs have better anti-corrosion and micro-tribological properties. • The anti-corrosion and micro-tribological mechanisms were both discussed. • Other novel materials will be prepared using the self-assembly method in future. [ABSTRACT FROM AUTHOR]

Attribute reduction is an important issue in knowledge discovery and data mining. Applying rough set theory, information systems based on crisp (or explicit) features can be easily done attribute reductions, but there exists rarely deeper discussion about attribute reduction in fuzzy information systems (i.e. information systems based on vague or undefinable features). A fully fuzzy information system is an information system where each of its attributes determines a fuzzy set on the object set, this paper investigates cc-reduction in this information system. The concept of class-consistent is first introduced. Then, the class-consistent relation cc(P) induced by the given attribute subset P in a fully fuzzy information system is proposed. Next, the class-consistent reduction (for short, cc-reduction) in a fully fuzzy information system is proposed and studied along with its corresponding algorithm. Moreover, considering that homomorphism is a kind of tools to study relationships between two fully fuzzy information systems, invariant characterizations of fully fuzzy information systems under homomorphisms are obtained. Finally, a numerical experiment is employed to illustrate the practical significance and possible applications of cc-reduction in a fully fuzzy information system. [ABSTRACT FROM AUTHOR]

Purpose The purpose of this paper is to investigate the tribological performance of graphene oxide (GO) sheets as water-based lubricant additive when ultra-high molecular weight polyethylene (UHMWPE) plates slid against 316L stainless steel ball using a reciprocating tribometre.Design/methodology/approach The factors influencing the tribological performance were considered, including the viscosity of the GO dispersion, normal load, sliding velocity and the roughness of UHMWPE. The surface microstructure and properties of UHMWPE were studied by means of scanning electron microscopy, laser confocal microscopy, Raman spectroscopy and contact angle measurements.Findings The results revealed that the GO dispersion reduced friction and sliding-wear. The surface images of the wear UHMWPE plates indicated that GO sheets were prone to adsorption on the surface and form a thin physical tribofilms at the substrate.Originality/value Based on the experimental findings for the evolution of the microstructure morphology and the development of subsurface cracks, less debris and cracking can be observed in the UHMWPE plates lubricated by GO dispersion. [ABSTRACT FROM AUTHOR]

The lubricant additives could be added into vegetable oil to improve the tribological. Two lubricant additives (GO-D and GO-T) were synthesized and characterized by the reaction between the carboxyl of graphene oxide (GO) and 1-dodecanethiol and tert -dodecyl mercaptan, respectively. The dispersion stability and tribological properties of GO-D and GO-T in rapeseed oil were investigated. The results show that the dispersion stability and tribological properties of GO-D in rapeseed oil are superior to that of GO-T, and both of them are better than that of GO. In addition, the surface morphology and chemical analysis of steel ball show that GO-D and GO-T sheets form absorption and tribochemical film on the rubbing surface. [ABSTRACT FROM AUTHOR]

Surgical sutures have different sizes, structures, whereas they are being used for various surgeries. The high friction performance of surgical sutures in the suturing process may cause inflammation and pain, leading to a longer recovery time. This paper presents an understanding of the tribological behavior of surgical suture with monofilament and multifilament structures, by means of a penetration friction apparatus (PFA). The results indicated that structure and surface topography of the surgical suture had a pronounced effect on the tribological interactions. It was found that the friction force and abrasion area of skin substitute with the penetration of polyglycolic acid (PGA) multifilament surgical suture were larger than that of Nylon monofilament surgical suture. Meanwhile, more abrasion at the pull-in boundary of skin substitute was observed compared with that at the pull-out boundary. [ABSTRACT FROM AUTHOR]

Two kinds of novel water-soluble ILs were synthesized and applied as lubricant additives in water-glycol. ILs, as the multifunctional and high efficiency additive, could drastically improve antiwear, friction-reducing and extreme pressure properties of water-glycol. SEM and EDS results indicated that the sample lubricated by PEG600MO phosphate-ammonium IL (P1) acquires higher active element content in the area with heavy wear, while that lubricated by PEG600MO phosphite-ammonium IL (P2) is relatively homogeneous on the worn surface with heavy and mild wear. L-edge XANES results showed that the tribofilm is composed of polyphosphate, and the increase of the polyphosphate chain length could improve the tribological properties. Additionally, the additive concentration, the rubbing time and the load could change the chain length of polyphosphate. [ABSTRACT FROM AUTHOR]

Rough set theory is concerned with the lower and upper approximations through a binary relation on the universe. Binary relations play an important role in this theory. This paper investigates similarity of binary relations based on complete Boolean lattices. First, rough approximations based on complete Boolean lattices are proposed through the predecessor neighborhood. Second, L-fuzzy topologies induced by binary relations are researched where L is a complete Boolean lattice. Thirdly, similarity of binary relations is introduced by using L-fuzzy topology and the fact that every binary relation is solely similar to some preorder relation is showed. Finally, as its theoretical expansion, a topological problem 'when can the given L-fuzzy topology be coincided with the L-fuzzy topology induced by some binary relation where L is a complete Boolean lattice?' is considered and this problem is answered by introducing L-fuzzy approximating spaces. [ABSTRACT FROM AUTHOR]

Increasing attention had been paid to the antibacterial and safety properties of membrane materials. The cellulose carbamate membrane (RCCM) without antibacterial properties would limit its applications in the food packaging industry. Herein, the antibacterial N-halamine regenerated cellulose carbamate membrane (RCCM-Cl) was manufactured by sodium hypochlorite solution treating the inherent amide of RCCM. The chemistry and mechanics properties of RCCM and RCCM-Cl were investigated. The antibacterial properties, cell compatibility, rechargeability and durability stability of RCCM-Cl were evaluated. Results demonstrated that the functional RCCM-Cl exhibits remarkable antibacterial activity which could sterilize Escherichia coli and Staphylococcus aureus within 1 min in the first contact period. The breaking strength, elongation at breaking, and transparency of RCCM-Cl retained 148.6 MPa, 8.1%, and 94%, respectively. In addition, antibacterial RCCM-Cl with active chlorine content exhibits excellent cell compatibility, regenerability, storage stability and stability in water. [Display omitted] • Novel antibacterial N-halamine cellulose membrane (RCCM-Cl) have been manufactured. • Functional RCCM-Cl exhibited remarkable antibacterial activity. • RCCM-Cl displayed superior storage stability and excellent biocompatibility. [ABSTRACT FROM AUTHOR]

• The resolution of GRACE-based water storage estimates is improved from 0.5° to 0.05° within the Haihe River Basin. • A comprehensive comparison is conducted between the pixel-scale and regional-scale downscaling schemes. • The accuracy of downscaled results is validated against high-resolution hydrological simulations and in-situ measurements. • The CC metrics of RF-based downscaling models are improved by 36.95% and 23.25% relative to original and simulated GWSA. The applications of the Gravity Recovery and Climate Experiment (GRACE) on local scales are obstructed owing to the coarser spatial resolution of GRACE observations. Much attempts recently have been taken to improve the resolution of GRACE-based water storage estimates based on machine learning algorithms, focusing on new algorithm development. However, there are still two deficiencies in previous GRACE downscaling research, namely the selection of input variables and the scale of model construction. In this study, the partial least squares regression (PLSR) model firstly is employed to identify the representative predictors associated with GRACE observations. Then, the performance of two different downscaling schemes (namely pixel-scale and regional-scale models) are comprehensively investigated, based on a machine learning algorithm known as random forest, to enhance the resolution of GRACE-based water storage estimates to the grid resolution as small as 5 km. The downscaled results are validated against hydrological model simulations and a number of in-situ groundwater level measurements within one of most rapidly urbanized basin in China, Haihe River Basin. The PLSR model recognizes four variables (namely evapotranspiration, temperature, land surface temperature, and soil moisture) as the predominant factors, acting as the predictors of downscaling models. Starting with the GRACE observations, two kinds of pixel and regional downscaling schemes are developed. The downscaled results were consistent each other and with the original GRACE data at a broad scale with the correlation up to 0.98. It was found that there was 3.20 times deviation of the results from the model simulation in computation of groundwater depletion rates within plain areas. In-situ water level measurements highlight that the downscaling models are improved by 36.95 % and 23.25 % in correlation relative to the original GRACE data and the simulated groundwater storage anomalies, respectively. Generally, the pixel-scale model is slightly better than the regional-scale model with 69 % (171 out of 249 observation wells) of higher correlation and 53 % (131 out of 249 observation wells) of smaller root mean squared error. The high-resolution results presented in this study can lead to better understanding on regional water resources and provide quantitative information to water management considering irrigation water use and groundwater consumption. [ABSTRACT FROM AUTHOR]

Latent heat flux (LE) plays an essential role in the hydrological cycle, surface energy balance, and climate change, but the spatial resolution of site-scale LE extremely limits its application potential over a regional scale. To overcome the limitation, five transfer learning models were constructed based on artificial neural networks (ANNs), random forests (RFs), extreme gradient boosting (XGBoost), support vector machine (SVM), and light gradient boosting machine (LightGBM) to upscale LE from site scale to regional scale in Heihe River basin (HRB). The instance-transfer approach that utilizes data samples outside of HRB was used in the transfer learning models. Moreover, the Bayesian-based three-cornered hat (BTCH) method was used to fuse the best three upscaling results from ANN, RF, and XGBoost models to improve the accuracy of the results. The results indicated that the transfer learning models perform best when the transfer ratio (the data samples ratio between external and HRB dataset) was 0.6. Specifically, the coefficient of determination (R2) and root mean squared errors (RMSE) of LE upscaled by ANN model was improved or reduced by 6% or 17% than the model without external data. Furthermore, the BTCH method can effectively improve the performance of single transfer learning model with the highest accuracy (R2 = 0.83, RMSE = 18.84 W/m2). Finally, the LE upscaling model based on transfer learning model demonstrated great potential in HRB, which may be applicable to similar research in other regions. [ABSTRACT FROM AUTHOR]

In the real world, there may exist manifold data (e.g., Boolean, categorical, real-valued, set-valued, interval-valued, image, decision and missing data or attributes) in an information system which is referred to as a hybrid information system with images (HISI). Handling an HISI is conducive to generalize applications of rough set theory. This paper studies entropy measurement for a hybrid information system with images and considers an application for attribute reduction. We first give the distance between information values on each attribute in an HISI. Then, we present tolerance relations on the object set of an HISI based on this distance. Next, we define the rough approximations in an HISI by means of the presented tolerance relations. Furthermore, we study entropy measurement for an HISI by using θ -information entropy, θ -conditional information entropy and θ -joint information entropy. Based on Kryszkiewicz's ideal, we introduce the concepts of θ -generalized decision and θ -consistent in an HISI. Finally, we apply entropy measurement to perform attribute reduction in a θ -consistent HISI. It is worth mentioning that attribute reduction based on generalized decision and common attribute reduction in a θ -consistent HISI are the same. [ABSTRACT FROM AUTHOR]

The launch of GRACE satellites has provided a new avenue for studying the terrestrial water storage anomalies (TWSA) with unprecedented accuracy. However, the coarse spatial resolution greatly limits its application in hydrology researches on local scales. To overcome this limitation, this study develops a machine learning-based fusion model to obtain high-resolution (0.25°) groundwater level anomalies (GWLA) by integrating GRACE observations in the North China Plain. Specifically, the fusion model consists of three modules, namely the downscaling module, the data fusion module, and the prediction module, respectively. In terms of the downscaling module, the GRACE-Noah model outperforms traditional data-driven models (multiple linear regression and gradient boosting decision tree (GBDT)) with the correlation coefficient (CC) values from 0.24 to 0.78. With respect to the data fusion module, the groundwater level from 12 monitoring wells is incorporated with climate variables (precipitation, runoff, and evapotranspiration) using the GBDT algorithm, achieving satisfactory performance (mean values: CC: 0.97, RMSE: 1.10 m, and MAE: 0.87 m). By merging the downscaled TWSA and fused groundwater level based on the GBDT algorithm, the prediction module can predict the water level in specified pixels. The predicted groundwater level is validated against 6 in-situ groundwater level data sets in the study area. Compare to the downscaling module, there is a significant improvement in terms of CC metrics, on average, from 0.43 to 0.71. This study provides a feasible and accurate fusion model for downscaling GRACE observations and predicting groundwater level with improved accuracy. [ABSTRACT FROM AUTHOR]

With the development of fine surgery and desire for low-injury methods, the frictional properties of surgical sutures are one of the crucial factors that can cause damage to tissue, especially for some fragile and sensitive human tissues such as the eyeball. In this study, dopamine hydrochloride and graphene oxide were used as external application agents to prepare a biological coating for the surface of multifilament surgical sutures. The effects of this biocoating on the surface morphology, chemical properties, mechanical properties, and tribological properties of surgical sutures were studied. The friction force and the coefficient of friction of surgical sutures penetrating through a skin substitute were evaluated using a penetration friction apparatus and a linear elastic model. The tribological mechanism of the coating on the multifilament surgical sutures was investigated according to the results of the tribological test. The results showed that there were uniform dopamine and graphene oxide films on the surface of the surgical sutures, and that the fracture strength and yield stress of the coated sutures both increased. The surface wettability of the surgical sutures was improved after the coating treatment. The friction force and the coefficient of friction of the multifilament surgical sutures with the dopamine hydrochloride and graphene oxide coating changed little compared to those of the untreated multifilament surgical sutures. [ABSTRACT FROM AUTHOR]

A fuzzy probability approximation space (FPA-space) is a approximation space (A-space) where three types of uncertainty (probability, fuzziness and roughness) are combined, which is obtained by putting probability distribution into a fuzzy approximation space (FA-space). This paper studies relationships between FPA-spaces and and their entropy measurement. Two types of fuzzy relation matrices are first defined by introducing the probability into a given fuzzy relation matrix in two ways, and on this basis, they are extended to two FA-spaces. Then, equality, dependence and independence between FPA-spaces are studied. Next, the distance between FPA-spaces is discussed. Moreover, the uncertainty for an FPA-space is measured by means of information entropy. Finally, the proposed information entropy is applied in the selection of classifier systems. Since fuzzy set theory, probability theory and rough set theory are aggregated together in an FPA-space, the obtained results of this paper may be helpful for dealing with practice problems with a sort of uncertainty. [ABSTRACT FROM AUTHOR]

Attribute selection in an information system is one of the important applications of rough set theory. This paper studies attribute selection for heterogeneous data based on information entropy. We first define information entropy in an information system with heterogeneous data and then put forward the notions of joint information entropy, conditional information entropy and mutual information entropy in a decision information system with heterogeneous data. We apply information entropy to perform attribute selection in a decision information system with heterogeneous data. We propose two attribute selection algorithms based on information entropy. Finally, we make experimental analysis and comparisons to illustrate the feasibility and efficiency of the proposed algorithms. [ABSTRACT FROM AUTHOR]

As an important model in the field of artificial intelligence, an information system is a database that stands for relationships between objects and attributes. A distributed fully fuzzy information system is an information system with distributed fully fuzzy data. This paper investigates measures of uncertainty for a distributed fully fuzzy information system. The fuzzy -equivalence relation, induced by a fully fuzzy information system by using Gaussian kernel method, is first obtained. Then, fuzzy information structures in a distributed fully fuzzy information system is introduced. Next, Dependency between fuzzy information structures is depicted from three aspects, information distance for calculating the difference between fuzzy information structures is proposed in the same distributed fully fuzzy information system. Moreover, properties of fuzzy information structures in a distributed fully fuzzy information system are given by means of the inclusion degree. Finally, granulation measure and entropy measure of a given distributed fully fuzzy information system is proposed by means of its fuzzy information structures. These results will be very helpful for establishing a framework of granular computing and understanding the essence of uncertainty in distributed fully fuzzy information systems. [ABSTRACT FROM AUTHOR]

Abstract Biomimetic texture could widen the application of titanium alloys materials in biological fields. In this work, the electrochemical corrosion and unidirectional tribological properties of Ti-6Al-4V substrate textured with three types of bionic hierarchical morphologies in the modified simulated body fluids (m -SBF) have been evaluated. The experimental results reveal that the corrosion resistance of textured surfaces is improved by reducing the β phase /α phase volume ratio on the substrate and increasing the texture density. Moreover, the effect of friction-reducing of 79% and friction-increasing of 47% in unidirectional sliding can be easily tuned with laser processing parameters. Interestingly, the textured surface displays anisotropic tribological behaviour in m -SBF solution, with reducing friction along the stacked ring direction and increasing friction in other directions. Graphical abstract Image 1 Highlights ● Three types of bionic hierarchical morphologies on the Ti-6Al-4V alloy substrates were fabricated using laser surface texturing. ● The effect of friction-reducing and friction-increasing in unidirectional sliding is easily achieved by tuning the laser processing parameters. ● The corrosion resistance of textured surfaces is improved by reducing the β phase /α phase volume ratio of the grain and increasing the texturing density. ● The mechanism of anisotropic tribological behaviour on textured Ti-6Al-4V surface is proposed. [ABSTRACT FROM AUTHOR]

Water shortages and groundwater depletion are critical issues in the world, leading to unsustainable agricultural production and adverse ecological impacts. Here, the new Multifactor-Quantitative joint Prediction Model (MQPM) is developed to quantitatively predict the Groundwater Storage Anomalies (GWSA), which includes an annual multifactor module and a monthly quantitative module. The correlative coefficients from two modules between simulated GWSA and observed GWSA reach up to 0.98 and 0.87, respectively. Taking Beijing as an example, results show that GWSA trends before South-to-North Water Diversion (SNWD) (2005–2014) and after SNWD (2015–2018) are at a rate of −3.00 × 108 m3/yr and 1.95 × 108 m3/yr, respectively, which reflects the effectiveness of water diversion. Additionally, the predicted results show that GWSA from the multifactor module will increase to 45.97 × 108 m3 by 2028. The quantitative module designs four scenarios under different climate changes and policies, from which the predicted GWSA with values ranging from 28.49 × 108 m3 to 63.06 × 108 m3. For the latter module, the groundwater level will recover to ∼8.9 m up to 2028, combining multiple favorable conditions. Finally, factors consisting of water diversion, climate change, and water-saving policies have a vital influence on groundwater variations, and contributions of these factors to the GWSA account for 46%, 27%, and 27%, respectively. [ABSTRACT FROM AUTHOR]

This paper focuses on surface analysis of tribofilm formed by a P-N type ionic liquid (trade name VANLUBE 672, abbreviated it as T672) in synthetic ester (pentaerythritol tetraoleate known as PETO) and water-based emulsion. PETO blended with T672 shows better anti-wear, anti-friction and anti-seizure properties than water-based emulsion blended with T672, which could originate from the tribofilm formed on the surface by characterization of SEM-EDS, CLSM and XANES. Tribofilm is composed of oligomeric phosphate and the polymerization and content of oligomeric phosphate could be affected by the medium and friction conditions under different test depths. The improvement of tribological properties is determined by oligomeric phosphate. And the change of oligomeric phosphate content on near surface of PETO (bulk surface for emulsion) is consistent with the change of tribological properties. [ABSTRACT FROM AUTHOR]

The stability of a titanium alloy screw implant in a spinal internal fixation system is primarily influenced by its tribological properties. We integrated laser texturing and anodic oxidation technology to fabricate surface micro/nanostructures on titanium alloys. The tribological properties of titanium alloys against bone were investigated by mimicking the progress of screw implantation. The results demonstrated that surface structure reduced the dynamic friction of the titanium alloy under dry conditions and increased the static friction under wet conditions. The low sliding friction in the dry state facilitated the initial implantation of the titanium alloy screws. Conversely, the high static friction in the wet state prevents post-implantation loosening of the titanium alloy screw and enhances its stability within bone tissue. [Display omitted] • Contact normal load between screw and bone was determined utilizing the classical model proposed by Hagiwara and Ohashi. • Laser texturing and anodic oxidation technology to fabricate surface micro/nanostructures on titanium alloys. • Tribological properties of titanium alloys against bone were investigated by mimicking the progress of screw implantation. [ABSTRACT FROM AUTHOR]

Clustering is a widely used technique in data mining applications and various pattern recognition applications, in which data objects are divided into groups. K-means algorithm is one of the most classical clustering algorithms. In this algorithm, the initial clustering centers are randomly selected, this results in unstable clustering results. To solve this problem, an optimized algorithm to select the initial centers is proposed. In the proposed algorithm, dispersion degree is defined, which is based on entropy. In the algorithm, all the objects are firstly grouped into a big cluster, and the object that has the maximum dispersion degree and the object that has the minimum dispersion degree are selected as the initial clustering centers from the initial big cluster. And then other objects in the biggest cluster are partitioned to the initial clusters to which the objects are nearest. The partition process will be repeated until the cluster number is equal to the specified value k. Finally, the partitioned k clusters and their cluster centers are applied to k-means algorithm as initial clusters and centers. Several experiments are conducted on real data sets to evaluate the proposed algorithm. The proposed algorithm is compared with traditional k-means algorithm and max-min distance clustering algorithm, and experimental results show that the improved k-means algorithm is stable in selecting initial clustering, because it can select unique initial clustering centers. The optimized algorithm's effectiveness and feasibility are also verified by experiments, and the algorithm can reduce the times of iterations and has more stable clustering results and higher accuracy. [ABSTRACT FROM AUTHOR]

• Nanosheets towards electrocatalytic sensors. • Nanosheets towards the gas sensors. • Nanosheets towards the epidermal sensors. Due to the extremely high area-to-thickness, nanosheets have become one of the rising research fields with vast applications. In comparison with other bulk materials, the 2D structure reveals unique physical (e.g., ultra-thin thickness, high flexibility and stretchability, excellent adhesion, etc.), electrochemical properties (e.g., superior electrical, catalytic properties, etc.) and expected to have immense potential for high-performance sensors. In this review, the state-of-the-art research in nanosheet-based sensing applications are discussed into three subtopics of the electrocatalytic sensor, gas sensor and epidermal sensor. [ABSTRACT FROM AUTHOR]

A covering information system as the generalization of an information system is an important model in the field of artificial intelligence. Uncertainty measurement is a critical evaluating tool. This paper investigates uncertainty measurement for a covering information system. The concept of information structures in a covering information system is first described by using set vectors. Then, dependence between information structures in a covering information system is introduced. Next, the axiom definition of granularity measure of uncertainty for covering information systems is proposed by means of its information structures, and based on this axiom definition, information granulation and rough entropy in a covering information system are proposed. Moreover, information entropy and information amount in a covering information system are also considered. Finally, we conduct a numerical experiment on the congressional voting records data set that comes from UCI Repository of machine learning databases, and based on this numerical experiment, effectiveness analysis from the angle of statistics is given to evaluate the performance of uncertainty measurement for a covering information system. These results will be helpful for understanding the essence of uncertainty in a covering information system. [ABSTRACT FROM AUTHOR]

Gravity Recovery and Climate Experiment (GRACE) satellites can effectively monitor terrestrial water storage (TWS) changes in large-scale areas. However, due to the coarse resolution of GRACE products, there is still a large number of deficiencies that need to be considered when investigating TWS changes in small-scale areas. Hence, it is necessary to downscale the GRACE products with a coarse resolution. First, in order to solve this problem, the present study employs modeling windows of different sizes (Window Size, WS) combined with multiple machine learning algorithms to develop a new machine learning spatial downscaling method (MLSDM) in the spatial dimension. Second, The MLSDM is used to improve the spatial resolution of GRACE observations from 0.5° to 0.25°, which is applied to Guantao County. The present study has verified the downscaling accuracy of the model developed through the combination of WS3, WS5, WS7, and WS9 and jointed with Random Forest (RF), Extra Tree Regressor (ETR), Adaptive Boosting Regressor (ABR), and Gradient Boosting Regressor (GBR) algorithms. The analysis shows that the accuracy of each combined model is improved after adding the residuals to the high-resolution downscaled results. In each modeling window, the accuracy of RF is better than that of ETR, ABR, and GBR. Additionally, compared to the changes in the TWS time series that are derived by the model before and after downscaling, the results indicate that the downscaling accuracy of WS5 is slightly more superior compared to that of WS3, WS7, and WS9. Third, the spatial resolution of the GRACE data was increased from 0.5° to 0.05° by integrating the WS5 and RF algorithm. The results are as follows: (1) The TWS (GWS) changes before and after downscaling are consistent, decreasing at −20.86 mm/yr and −21.79 mm/yr (−14.53 mm/yr and −15.46 mm/yr), respectively, and the Nash–Sutcliffe efficiency coefficient (NSE) and correlation coefficient (CC) values of both are above 0.99 (0.98). (2) The CC between the 80% deep groundwater well data and the downscaled GWS changes are above 0.70. Overall, the MLSDM can not only effectively improve the spatial resolution of GRACE products but also can preserve the spatial distribution of the original signal, which can provide a reference scheme for research focusing on the downscaling of GRACE products. [ABSTRACT FROM AUTHOR]

The Gravity Recovery and Climate Experiment (GRACE) satellite solutions have been considerably applied to assess the reliability of hydrological models on a global scale. However, no single hydrological model can be suitable for all regions. Here, a New Statistical Correction Hydrological Model Weighting (NSCHMW) method is developed based on the root mean square error and correlation coefficient between hydrological models and GRACE mass concentration (mascon) data. The NSCHMW method can highlight the advantages of good models compared with the previous average method. Additionally, to verify the effect of the NSCHMW method, taking the Haihe River Basin (HRB) as an example, the spatiotemporal patterns of Terrestrial Water Storage Anomalies (TWSA) in HRB are analyzed through a comprehensive comparison of decadal trends (2003–2014) from GRACE and different hydrological models (Noah from GLDAS-2.1, VIC from GLDAS-2.1, CLSM from GLDAS-2.1, CLSM from GLDAS-2.0, WGHM, PCR-GLOBWB, and CLM-4.5). Besides, the NSCHMW method is applied to estimate TWSA trends in the HRB. Results demonstrate that (1) the NSCHMW method can improve the accuracy of TWSA estimation by hydrological models; (2) the TWSA trends continue to decrease through the study period at a rate of 15.7 mm/year; (3) the WGHM and PCR-GLOBWB have positive reliability with respect to GRACE with r > 0.9, while all the other models underestimate TWSA trends; (4) the NSCHMW method can effectively improve RMSE, NES, and r with 3–96%, 35–282%, 1–255%, respectively, by weighting the WGHM and PCR-GLOBWB. Indeed, groundwater depletion in HRB also proves the necessity of the South-North Water Diversion Project, which has already contributed to groundwater recovery. [ABSTRACT FROM AUTHOR]

The surface porous ultrahigh molecular weight polyethylene (UHMWPE) composites were successfully fabricated with NaCl and graphene oxide (GO) in the hot-pressing procedure. The GO sheets were evenly dispersed in UHMWPE with the sedimentation method of GO in saturated NaCl. The morphologies, chemical compositions, mechanical, and tribological properties of GO and surface porous GO/NaCl/UHMWPE were investigated. The results show that GO sheet and NaCl could be evenly dispersed in UHMWPE. The regular pores are present on the surface of UHMWPE after NaCl dissolution in distilled water. The wear resistance properties are improved significantly, and the friction properties increased slightly with the addition of GO and NaCl. [ABSTRACT FROM AUTHOR]

The poor antiwear properties of Ti–6Al–4V have restricted its applications as biomedical materials. In this work, microgrooves with different groove width and graphene oxide (GO) coating were constructed on the surface of Ti–6Al–4V by laser processing and chemical assembly, respectively. The effects of microgroove width on the anticorrosion and biotribological properties of GOs-coated Ti–6Al–4V alloys were systematically investigated. The results indicate that the GOs-coated sample with 45 μm groove width (Ti-45-GO) can effectively improve the anticorrosion of Ti–6Al–4V, due to the surface microstructure homogenization from Ti−45 substrate and the shielding effect of GO coatings. Furthermore, the Ti-45-GO sample exhibits excellent antiwear properties, owing to the capture of wear debris of microgrooves and the high strength and resilience from GO coatings. Image 1 • GOs-coated laser microgrooved Ti–6Al–4V with different groove width are prepared. • The effects of groove width on anticorrosion and antiwear of Ti–6Al–4V are studied. • Groove width of 45 μm can better enhance anticorrosion and antiwear of Ti–6Al–4V. • The anticorrosion and biotribological mechanisms were both discussed. • The treatment can be used to improve anticorrosion and antiwear of other materials. [ABSTRACT FROM AUTHOR]

Three-way decisions are effective and heuristic methods in information processing, moreover, it provides a trisecting-and-acting framework for complex problem solving. In this paper, combining with the practical application scenario, we propose a novel three-way decisions approach and apply it to medical diagnosis. First, we build an information system which is called a hybrid information system with images by considering the characteristics of the examination items of nephritis, including urinary color, urinary tuberculosis, pH, red blood cell count, urinary irritation, computed tomography, white blood cell count and so on. Second, to describe two objects of the conditional attribute set in a hybrid information system with images, we propose the hybrid distance based on Euclidean distance. Then, the tolerance relation induced by this system is constructed. In addition, considering that missing values exist in a hybrid information system with images, interval-valued numbers are used to obtain the loss function. Given different types of parameters can respond the level of the tolerance relation and the risk preference of decision makers, and the decision rules are shown in tabular forms. Finally, an illustration is showed to verify the feasibility and reasonability of the proposed method. [ABSTRACT FROM AUTHOR]

A novel Eu-MOF sensor, named as [Eu 5 (DBA) 3 n (1), has been prepared based on 3,5-di(2′,4′-dicarboxylphenyl) benozoic acid (H 5 DBA) and europium nitrate under solvothermal condition. Structural analysis shows that the binuclear and polynuclear inorganic building untis to form stable microporous structure based on the wholly deprotonated DBA ligands. The microporous structure of 1 has been verified by the gas adsorption experiment of N 2. Fluorescence studies show that Eu-MOF can detect acetone molecules, Cu2+ ion and Cr 2 O 7 2− anion with high sensitivity and selectivity, and can also be used for electrochemical detection of exposed 2,4,6-trinitrophenol (TNP) in water. The high selective and sensitive detection ability of complex 1 might make it a potential multifunctional sensor in the future. One novel Eu-MOF sensor has been prepared based on 3,5-di(2′,4′-dicarboxylphenyl) benozoic acid and europium nitrate under solvothermal condition.Fluorescence studies show that Eu-MOF can detect acetone, Cu2+ ion and Cr 2 O 7 2− anion with high sensitivity and selectivity, and can also be used for electrochemical detection of explosive 2,4,6-trinitrophenol (TNP) in water. Image 1 [ABSTRACT FROM AUTHOR]

• Metal-alginate fibers were prepared by the metal-calcium coagulation bath. • Metal-alginate fibers improved flame retardancy and mechanical properties. • The valence states of metal ions were not related to the properties of fibers. • FT-IR and 13C CP/MAS NMR were employed to analysis the structure of fibers. In order to improve the mechanical properties of alginate fiber and enrich its application properties, the metal-alginate fibers were produced with wet spinning in the coagulation bath of Zn2+, Ba2+, Cu2+, Al3+ ions blended with Ca2+ ions. FT-IR and 13C NMR were used to characterize the binding mode of alginic acid with metal ions and the arrangement of G and M groups in the molecular chain. The flame retardancy, mechanical and antibacterial properties of metal-alginate fiber were improved, while its water absorption was decreased. The results of Thermogravimetric (TG) and Limiting oxygen index (LOI) showed that the flame retardancy of metal-alginate fibers was better than that of calcium alginate fibers. The combination of metal ions and alginic acid has different improvement effect of mechanical strength and antimicrobial activity against Escherichia coli and Staphylococcus aureus. The multi-functional fiber is expected to be used in medical textiles and new textile fibers. [ABSTRACT FROM AUTHOR]