Particle filter based on iterated importance density function and parallel resampling

The design, analysis and parallel implementation of particle filter(PF) were investigated. Firstly, to tackle the particle degeneracy problem in the PF, an iterated importance density function(IIDF) was proposed, where a new term associating with the current measurement information(CMI) was introduced into the expression of the sampled particles. Through the repeated use of the least squares estimate, the CMI can be integrated into the sampling stage in an iterative manner, conducing to the greatly improved sampling quality. By running the IIDF, an iterated PF(IPF) can be obtained. Subsequently, a parallel resampling(PR) was proposed for the purpose of parallel implementation of IPF, whose main idea was the same as systematic resampling(SR) but performed differently. The PR directly used the integral part of the product of the particle weight and particle number as the number of times that a particle was replicated, and it simultaneously eliminated the particles with the smallest weights, which are the two key differences from the SR. The detailed implementation procedures on the graphics processing unit of IPF based on the PR were presented at last. The performance of the IPF, PR and their parallel implementations are illustrated via one-dimensional numerical simulation and practical application of passive radar target tracking.

Natural and modified food hydrocolloids as gluten replacement in baked foods:Functional benefits

Gluten,the protein responsible for the superior viscoelastic properties of refined wheat flour dough over glutenfree cereals,causes celiac disease in people susceptible to gluten-allergy.Moreover,the sustainability of using wheat flour in baked foods is threatened by its high cost,especially in countries that depend on imported wheat for their bakery industry.Research has shown that hydrocolloids serve as gluten replacements in baked foods,in response to these challenges.Food hydrocolloids are a class of high-molecular weight polysaccharides and proteins,which serve as functional ingredients in the food industry that modify the foods’rheological and textural properties.They function as stabilizers,viscosity modifiers,gelling agents,water binders,fibres,and inhibitors of ice crystal in foods.Further,food hydrocolloids have also been reported to possess health-promoting properties,such as lowering of postprandial blood glucose and plasma cholesterol concentrations,colon cancer prevention,and modulation of intestinal transit and satiety.They are obtained from plants,animals or microorganisms,and can be used in their natural or modified forms.The aim of this paper is to review the functional benefits of natural and modified hydrocolloids as gluten replacements in baked foods,emphasizing their physicochemical,nutraceutical,and sensorial importance.The application effects of food hydrocolloids as gluten substitutes in gluten-free baked products’quality were discussed.Also,some practical approaches to improve the quality of gluten-free baked products,in response to an increasing consumers’demand and the rising cost of refined wheat flour were highlighted.

Concepts of keystone species and species importance in ecology

This paper discussed the keystone species concept and introduced the typical characteristics of keystone species and their identification in communities or ecosystems. Based on the research of the keystone species, the concept of species importance (SI) was first advanced in this paper. The species importance can be simply understood as the important value of species in the ecosystem, which consists of three indexes: species structural important value (SIV), functional important value (FIV) and dynamical important value (DIV). With the indexes, the evaluation was also made on species importance of arbor trees in the Three-Hardwood forests (Fraxinus mandshurica, Juglans mandshurica, and Phellodendron amurense) ecosystem.

Simplified unscented particle filter for nonlinear/non-Gaussian Bayesian estimation

Particle filters have been widely used in nonlinear/non- Gaussian Bayesian state estimation problems. However, efficient distribution of the limited number of particles （n state space remains a critical issue in designing a particle filter. A simplified unscented particle filter （SUPF） is presented, where particles are drawn partly from the transition prior density （TPD） and partly from the Gaussian approximate posterior density （GAPD） obtained by a unscented Kalman filter. The ratio of the number of particles drawn from TPD to the number of particles drawn from GAPD is adaptively determined by the maximum likelihood ratio （MLR）. The MLR is defined to measure how well the particles, drawn from the TPD, match the likelihood model. It is shown that the particle set generated by this sampling strategy is more close to the significant region in state space and tends to yield more accurate results. Simulation results demonstrate that the versatility and es- timation accuracy of SUPF exceed that of standard particle filter, extended Kalman particle filter and unscented particle filter.

Quadrature Kalman particle fitler

In order to resolve the state estimation problem of nonlinear/non-Gaussian systems, a new kind of quadrature Kalman particle filter （QKPF） is proposed. In this new algorithm, quadrature Kalman filter （QKF） is used for generating the impor- tance density function. It linearizes the nonlinear functions using statistical linear regression method through a set of Gaussian- Hermite quadrature points. It need not compute the Jacobian matrix and is easy to be implemented. Moreover, the importantce density function integrates the latest measurements into system state transition density, so the approximation to the system poste- rior density is improved. The theoretical analysis and experimen- tal results show that, compared with the unscented partcle filter （UPF）, the estimation accuracy of the new particle filter is improved almost by 18%, and its calculation cost is decreased a little. So, QKPF is an effective nonlinear filtering algorithm.

Fuzzy metric based on the distance function of plane and its application in optimal scheduling problems

Measuring the difference between fuzzy numbers is often needed in many fuzzy optimization problems such as manufacturing system production line scheduling with uncertainty environments. In this paper, based on the distance function of plane R2 and the level importance function, we establish the UID-metric and LPID-metric of measuring the difference between fuzzy numbers, and discuss the basic properties of UID-metric and LPID-metric, and prove that fuzzy number spaces are metric spaces about UID-metric and LPID-metric if and only if the level importance function I(λ)≠0 almost everywhere on [0, 1]. Further, we discuss the convergence, separability and completeness of UID-metric and LPID-metric based on the norms of plane R2. Finally, we analyze the characteristics of UID-metric and LPID-metric by some application examples.

青藏高原生态系统功能稳定性演化特征及分区

The Qinghai-Tibet Plateau(QTP),also known as the Third Pole of the Earth,is a vital ecological security barrier for China.It is a tremendously sensitive region affected by the impacts of global climate change.The escalating intensity of climate change has presented profound challenges to its ecosystem functions and stability.This study first analyzes the spatiotemporal variations of the QTP ecosystem patterns and the key functions of the Plateau including water conservation,soil conservation,and windbreak and sand fixation from 2000 to 2020.It clarifies the regional differences in ecosystem functions and their importance,further evaluates the stability of ecosystem functions,and lays a scientific foundation for an ecological civilization on the Plateau by implementing conservation and restoration projects.The main results show that:(1)From 2000 to 2020,the wetland area in the QTP increased,while the grassland area significantly decreased.There were improvements in water conservation and windbreak and sand fixation capacities,with annual rates of change being 3.57m~3·ha^(-1)·a^(-1)and 0.23 t·ha^(-1)·a^(-1),respectively.However,the overall soil conservation trend declined during the same period,with an annual change rate of-0.16 t·ha^(-1)·a^(-1).(2)The core areas of water conservation,soil conservation,and windbreak and sand fixation on the QTP accounted for 12.7%,13.9%,and 14.2%of the total area,respectively.The core water conservation areas are mainly the southeastern QTP,Sanjiangyuan,and Naqu,while the core windbreak and sand fixation areas were concentrated in the central and western parts of the Plateau.The core soil conservation areas surrounded the entire interior of the Plateau.(3)From 2000 to 2020,the water conservation,soil conservation,and windbreak sand-fixation function on the QTP had higher stability in the southeastern and central parts,while stability was lower in the western region.Considering the stability assessment and ecological protection and restoration practices,the QTP can be divided into three major categories and 16 ecological functional zones.Differentiated ecological protection and restoration efforts can be implemented based on the different core ecosystem functions and zoning.

The Bo-Tai Line:Establishing the concepts of a balanced regional development line and a national development backbone

Promoting regional coordinated development strategy is one of the important strategies in the new period of China.Faced with the reality of unbalanced and insufficient regional development in China,it is objectively necessary to construct one or more main axes supporting the coordinated and balanced development of regions to become the identification line representing the pattern of coordinated regional development.The results show that the Bo-Tai line,the northwest-southeast axis connecting Bole of Xinjiang and Taipei of Taiwan,can be built into national development backbone line and regional balanced development line,just perpendicular to Hu Line.In 2016,the area of southwest half and northeast half of Bo-Tai Line accounts for 60%:40%,while the population accounts for 45%:55%,the economic aggregate accounts for 40%:60%,the per capita GDP ratio accounts for 44%:56%,the population density ratio accounts for 38%:62%,the economic density ratio accounts for 32%:68%,and the urbanization level ratio accounts for 48%:52%.The main average indicators are gradually tending to balanced development pattern.Further analysis shows that Bo-Tai Line is a strategic shoulder pole connecting two core zones of"the Belt and Road",and is the peaceful reunification line of China's national tranquility and Taiwan's return.Bo-Tai Line is also a solid line supported and connected by comprehensive transportation channels and a Pipa type symmetrical line for the development of cities and urban agglomerations.It is the backbone of the two-way opening up and the linkage development line between land and sea.It is also an important dividing line that promotes the coordinated development of the eastern,central and western regions,and addresses the imbalance and inadequacy of regional development.Bo-Tai Line plays an irreplaceable strategic role in promoting the coordinated and balanced regional development.It is suggested that the construction of Bo-Tai Line should be included in the national development strategy,and the development strategic plan of Bo-Tai Line should be formulated to fully release the multiple potential functions.We should build three strategic support points:the northwest endpoint,the central strategic node and the southeast endpoint;carry out a comprehensive scientific investigation of the Bo-Tai Line,and strengthen the scientific cognition and publicity;promote China's development in a higherlevel,higher-quality,more coordinated,safer and more civilized direction.Let Chinese know about the Bo-Tai Line,let the world know about the Bo-Tai Line,and let the Bo-Tai Line truly become the backbone of the great rejuvenation of the Chinese nation.

Regional moment-independent sensitivity analysis with its applications in engineering

Traditional Global Sensitivity Analysis（GSA） focuses on ranking inputs according to their contributions to the output uncertainty.However,information about how the specific regions inside an input affect the output is beyond the traditional GSA techniques.To fully address this issue,in this work,two regional moment-independent importance measures,Regional Importance Measure based on Probability Density Function（RIMPDF） and Regional Importance Measure based on Cumulative Distribution Function（RIMCDF）,are introduced to find out the contributions of specific regions of an input to the whole output distribution.The two regional importance measures prove to be reasonable supplements of the traditional GSA techniques.The ideas of RIMPDF and RIMCDF are applied in two engineering examples to demonstrate that the regional moment-independent importance analysis can add more information concerning the contributions of model inputs.

Improved Flight Conflict Detection Algorithm Based on Gauss-Hermite Particle Filter

In order to improve the accuracy of free flight conflict detection and reduce the false alarm rate, an improved flight conflict detection algorithm is proposed based on Gauss-Hermite particle filter（GHPF）. The algorithm improves the traditional flight conflict detection method in two aspects：（i） New observation data are integrated into system state transition probability, and Gauss-Hermite Filter（GHF） is used for generating the importance density function.（ii） GHPF is used for flight trajectory prediction and flight conflict probability calculation. The experimental results show that the accuracy of conflict detection and tracing with GHPF is better than that with standard particle filter. The detected conflict probability is more precise with GHPF, and GHPF is suitable for early free flight conflict detection.