Tri-Partition Alphabet-Based State Prediction for Multivariate Time-Series

Recently, predicting multivariate time-series (MTS) has attracted much attention to obtain richer semantics with similar or better performances. In this paper, we propose a tri-partition alphabet-based state (tri-state) prediction method for symbolic MTSs. First, for each variable, the set of all symbols, i.e., alphabets, is divided into strong, medium, and weak using two user-specified thresholds. With the tri-partitioned alphabet, the tri-state takes the form of a matrix. One order contains the whole variables. The other is a feature vector that includes the most likely occurring strong, medium, and weak symbols. Second, a tri-partition strategy based on the deviation degree is proposed. We introduce the piecewise and symbolic aggregate approximation techniques to polymerize and discretize the original MTS. This way, the symbol is stronger and has a bigger deviation. Moreover, most popular numerical or symbolic similarity or distance metrics can be combined. Third, we propose an along–across similarity model to obtain the k-nearest matrix neighbors. This model considers the associations among the time stamps and variables simultaneously. Fourth, we design two post-filling strategies to obtain a completed tri-state. The experimental results from the four-domain datasets show that (1) the tri-state has greater recall but lower precision; (2) the two post-filling strategies can slightly improve the recall; and (3) the along–across similarity model composed by the Triangle and Jaccard metrics are first recommended for new datasets.

Multivariate State Estimation Technique Combined with Modified Information Entropy Weight Method for Steam Turbine Energy Efficiency Monitoring Study

An energy efficiency monitoring method of the steam turbine system is studied in this paper. Multivariate state estimation technique (MSET) is utilized to compare the actual monitoring parameters and the healthy data of the equipment in normal working condition with a multi parameter estimation model. Due to the limitation of a single heat rate index in evaluating energy efficiency variation, the energy efficiency deviation degree combined with improved information entropy weight is proposed to judge the steam turbine’s operation condition levels. The index value in the modified weight method has been searched for more steady weight values calculated by information entropy values with small variation. Taking a 600 MW unit as an example, the energy efficiency levels of the unit under a 550 MW normal working condition are clustered into four groups, testifying the MSET model correctness and calculating the deviation degree value. Then, the energy efficiency status monitoring model is utilized to record residuals of actual data and estimated data during abnormal energy efficiency period. The residuals over deviation degree are then marked and judged as related with the abnormal data. The results show that the MSET model can timely and accurately judge the change of unit operation state, and the deviation degree calculated by the modified information entropy weight method can provide earlier warnings for the abnormal energy efficiency working conditions.

Measuring Synchronization between Spikes and Local Field Potential Based on the Kullback–Leibler Divergence

Neurophysiological studies have shown that there is a close relationship between spikes and local field potential (LFP), which reflects crucial neural coding information. In this paper, we used a new method to evaluate the synchronization between spikes and LFP. All possible phases of LFP from −π to π were first binned into a freely chosen number of bins; then, the probability of spikes falling in each bin was calculated, and the deviation degree from the uniform distribution based on the Kullback–Leibler divergence was calculated to define the synchronization between spikes and LFP. The simulation results demonstrate that the method is rapid, basically unaffected by the total number of spikes, and can adequately resist the noise of spike trains. We applied this method to the experimental data of patients with intractable epilepsy, and we observed the synchronization between spikes and LFP in the formation of memory. These results show that our proposed method is a powerful tool that can quantitatively measure the synchronization between spikes and LFP.

Effect of off-sized balls on contact stiffness and stress and analysis of the wear prediction model of linear rolling guideways

The characteristics between the rolling balls and raceways are the key to study a linear rolling guideway (LRG). In this paper, the contact stresses of an LRG with off-sized balls incorporating the variation of the contact angle are given by the established LRG joint model. Moreover, the effect of the location, number, and the deviation degree of the off-sized balls on the stress distribution are studied. In addition, the contact stress distribution between the balls and raceway for different arrangement cases of the off-sized balls are analyzed. The random arrangement case can improve the stiffness and service life of the LRG. Based on the Archard wear theory, the wear prediction model of the LRG is established and the displacements and angular displacements of the slider caused by wear in reciprocating motion are obtained. The effectiveness of the contact stiffness and wear prediction model of the LRG is verified by simulations and analysis.

Interaction between Land Financing Strategy and the Implementation Deviation of Local Governments’ Cultivated Land Protection Policy in China

The deviation of implementation of China’s cultivated land protection policy is the core problem urgently needing to be solved in the process of protecting the country’s cultivated land. This paper aims to explain the universality of this implementation deviation from the perspective of the spatial interaction of fiscal land strategies. Based on the data of 30 provinces in China from 2000 to 2015, the spatial Durbin model is used to validate the corresponding theoretical hypothesis. The results show that: (1) At the national or regional level, the given local government’s behavior with regard to land conveyance and land-orientation investment will aggravate implementation deviations of the cultivated land protection policy in the local area. (2) Land conveyance and land-orientation investment behaviors cause a spatial spillover effect. As a result, these behaviors not only exacerbate the implementation deviation of the cultivated land protection policy in the local area, but also exacerbate this deviation in adjacent areas. (3) The spatial spillover effects of land conveyance and land-orientation investment strategies in the eastern, central and western regions of China show marked differences. However, in general, compared with the land transfer strategy, the spatial interactions of the land-orientation investment strategy represent the more important factor that gives rise to the widespread deviation in the implementation of the cultivated land protection policy. (4) The transformation of the performance appraisal system can help to weaken the interactive behavior of the land financing strategy. This can, in turn, not only alleviate the deviation degree of the implementation of the local cultivated land protection policy, but also the deviation degree of the implementation of the latter in adjacent areas.

Ocular Motor Behavior Monitor in Intermittent Exotropia by Eye Tracker

Purpose: Eye movement in intermittent exotropia (IXT) patients is characterized by viability and uncertainty, however, conventional strabismus inspection methods cannot reflect these important qualities. Here, we sought to study the ocular motor behavior of IXT under different viewing conditions by eye tracker.Methods: Sixty-one IXT patients (33 males and 28 females) and 15 age-matched control participants were recruited for this study. An eye tracker equipped with a high-speed camera and MATLAB software was employed to monitor and record eye movement as well as eye position in included subjects with 3D shutter glasses at a normal reading distance (57 cm).Results: By using an eye tracker, our data showed that 90% of the included IXT patients lost their control and showed exotropia in 1.5±2.1s. The average deviation degree measured by the eye tracker was 32.9±11.5△, ranging from 6 to 50△, and reached its maximum deviation degree at 36.9±12.4△, with a mean time of 2±1.5s. Although a significant difference exists in the strabismus quantification between the prism test and the eye tracker, the test results obtained from these two methods were positively correlated. Moreover, by using the eye tracker, the fixation instability of IXT patients could be easily recorded and analyzed. In addition, the included IXT patients were divided into three types according to their ocular motor behavior as monitored by an eye tracker.Conclusion: Eye trackers could not only provide continuous, precise and effective strabismus assessments but also analyze ocular motor behavior over a period of time in IXT patients.

Joint Equivalence Design and Analysis of a Tensegrity Joint

We propose a method to design a tensegrity joint, making its elastic deformation an accurate joint-like motion, such as a rotation around the designed rotational center. The tensegrity joint can be a three rotational degree-of-freedom (DOF) joint through this method. Axis drift is presented as a design criterion to describe the rotational center's deviation degree concerning the compliance center since the rotational center is not fixed to one point for different positions of the tensegrity joint. The axis drift is designed to be in a prescribed range so that the tensegrity joint is approximately equivalent to a rigid joint. In other words, the tensegrity joint's elastic response under external torque and force becomes precise rigid-joint-like kinematics and can replace rigid joints to transfer motion, force, and energy. A large-size tensegrity joint is developed to verify the joint equivalence experimentally. The experimental results show that the tensegrity joint achieved maximum dimensionless axis drift less than 2%, and indicate an excellent joint equivalence. The tensegrity joints' ability to replace rigid joints as modular joints to construct a hyper redundant serial structure is demonstrated using a tensegrity robotic arm. The proposed tensegrity compliant joint has notable benefits of tensegrity structure such as high mechanical efficiency, modularity, and scalability, and can be extended to many robotic applications, such as large-size serial robotic arms and snake-like robots.

Trapezoidal Hesitant Intuitionistic Fuzzy Numbers and Their Applications to Multiple-Criteria Decision Making Problems

In this paper, we introduce an extension theory of the trapezoidal intuitionistic fuzzy numbers under intuitionistic hesitant fuzzy sets called trapezoidal hesitant intuitionistic fuzzy number (THIF-number). This new theory provides very effectively to model uncertainties of some events by several different trapezoidal intuitionistic fuzzy numbers based on the same support set in the set of real numbers R. Also, to demonstrate the application of this theory, a new multi-criteria decision-making(MCDM) method based on THIF-numbers is presented. To do this, we first propose operations of THIF-numbers with properties. We second give score, standard deviation degree, deviation degree of THIF-numbers to compare THIF-numbers. We third develop geometric operators and arithmetic operators of THIF-number. Finally, a numerical example is presented to illustrate the application of the developed method in THIF-numbers.

DEA Cross-Efficiency Aggregation with Deviation Degree Based on Standardized Euclidean Distance

Data envelopment analysis (DEA) has been extended to cross-efficiency to provide better discrimination and ranking of decision-making units (DMUs). Current researches about cross-efficiency mainly focus on the non-uniqueness of optimal solution of linear programming and information aggregation. As a common distance metric, standardized Euclidean distance is introduced to define the discrimination power between two vectors and the deviation degree for measuring the difference between the individual preference and group ideal preference. Based on above definitions, an alternative method is presented to compare multiple optimal solutions, and further, a universal weighted cross-efficiency model considering both dynamic adjustment of weights and preference formulation is constructed for evaluation and ranking. Two numerical examples are given to illustrate the effectiveness of the comparison method for multiple optimal solutions and weights determination method of DMUs, respectively. At last, a practical application aimed at evaluating environmental treatment efficiency in western area of China is given. Comparative analysis shows that our model could be more moderate, flexible, and general than some available models and methods, which can extend the theoretical research of cross-efficiency evaluation.