Multi-dimensional scattering properties diagnosis system of scale aircraft model in an anechoic chamber

Aiming at the concept of ＂diagnosis＂, a simple and effective broadband radar cross section （RCS） measurement system is constructed, and some multi-dimensional scattering properties diagnosis techniques are presented based on the system. Firstly, a stepped-frequency signal is employed to achieve high range resolution, combining with a variety of signal processing tech- niques. Secondly, cross-range resolution is gained with a rotating table, and the high-resolution two-dimensional （2-D） imaging of the scale model is obtained by the microwave imaging theory. Finally, two receiving antennas with a small distance in altitude are used, and the three-dimensional （3-D） height distribution of scattering points on the scale model is extracted from the phase of images. Some typical bodies and a scale aircraft model are diagnosed in an anechoic chamber. The experimental results show that, after scaling with a metal sphere, the accurate one- dimensional （l-D） RCS pattern of the model is obtained, and it has a large dynamic range. When the bandwidth of the transmitting signal is 4 GHz, the resolution of the 2-D image can reach to 0.037 5 m. The 3-D height distribution of scattering points is given by interferometric measurement. This paper provides a feasible way to obtain high-precision scattering properties parameters of the scale aircraft model in a conventional rectangular anechoic chamber.

ON MULTI-DIMENSIONAL SONIC-SUBSONIC FLOW

In this paper, a compensated compactness framework is established for sonicsubsonic approximate solutions to the n-dimensional （n ≥ 2） Euler equations for steady irrotational flow that may contain stagnation points. This compactness framework holds provided that the approximate solutions are uniformly bounded and satisfy Hloc^-1（Ω） compactness conditions. As illustration, we show the existence of sonic-subsonic weak solution to n-dimensional （n ≥ 2） Euler equations for steady irrotational flow past obstacles or through an infinitely long nozzle. This is the first result concerning the sonic-subsonic limit for n-dimension （n ≥ 3）.

Multi-Dimensional Thoughts on English Classroom Teaching Techniques

English Language teaching involves various English teaching techniques in terms of listening,speaking,reading,writ ing and the like skills.Traditional teaching ways are mostly discussed from that standpoint.Here,some new English classroom teaching techniques are introduced and evaluated in a dimensional perspective,which relate to such elements as the students,the teacher,classroom organization and management,and instructional strategies,etc.It makes English classroom teaching more effec tive,thus improve English classroom teaching results.So,it’s advisable for English teachers to reconsider and reevaluate their teaching strategy and result in language classroom from a new multi-dimensional angle in order to improve English teaching effi ciency.

Multi-Dimensional Pedestrian System on the New Campus of University of Macao

The Multi-dimensional Pedestrian System( MPS) is an integral part of the new campus of University of Macao. It observes the principle of "pedestrian first " and features a pedestrian-vehicle dividing system.Based on a comprehensive analysis of the location,climate,ecology and other factors of the project site,the conception of the idea of MPS and the related researches are illustrated. The transportation features of the MPS,as summarized,include multi-dimensions,short-distance and weather-resistance. Its features for the sake of livability include integration of nature, respect for the environment and sharing of landscape. Upon the completion of the project, the effects on its users were tested. Finally, some constructive rules for the construction of similar campus pedestrian systems were proposed.

Multi-index analysis of the melting process of laterite metallized pellet

Herein, a multi-index analysis of the nickel content of an alloy, output rate of the alloy, nickel recovery rate, and iron recovery rate during the melting of laterite metallized pellets was performed. The thermodynamic reduction behavior of oxides such as NiO, FeO, Fe_3 O_4, and Cr_2 O_3 was studied using the FactSage software, which revealed that SiO_2 is not conducive to the reduction of iron oxides, whereas the addition of basic oxides such as CaO and MgO is beneficial for the reduction of iron oxides. On the basis of a comprehensive analysis to achieve greater nickel recovery and lower iron recovery rates, the optimum experimental parameters in the orthogonal experiment were A3 B1 C3(t = 30 min, C/O = 0.4, R = 1.2); the indicators wNi, φalloy, ηNi, and ηFe had values of 15.0 wt%, 12.1%, 44.9%, and 96.4%, respectively. In single-factor experiments, increasing basicity(R) substantially improved the separation effect in the low-basicity range 0.5 ≤ R ≤ 0.8 but not in the high-basicity range 0.8 ≤ R ≤ 1.2. Similar results were obtained for the effect of the C/O ratio. Moreover, the recovery rate of nickel increased with increasing recovery rate of iron.

Urban flood risk assessment under rapid urbanization in Zhengzhou City,China

With accelerated urbanization and climate change,urban flooding is becoming more and more serious.Flood risk assessment is an important task for flood management,so it is crucial to map the spatial and temporal distribution of flood risk.This paper proposed an urban flood risk assessment method that takes into account the influences of hazard,vulnerability,and exposure,by constructing a multi-index urban flood risk assessment framework based on Geographic Information System(GIS).To determine the weight values of urban flood risk index factors,we used the analytic hierarchy process(AHP).Also,we plotted the temporal and spatial distribution maps of flood risk in Zhengzhou City in 2000,2005,2010,2015,and 2020.The analysis results showed that,the proportion of very high and high flood risk zone in Zhengzhou City was 1.362%,5.270%,4.936%,12.151%,and 24.236%in 2000,2005,2010,2015,and 2020,respectively.It is observed that the area of high flood risk zones in Zhengzhou City showed a trend of increasing and expanding,of which Dengfeng City,Xinzheng City,Xinmi City,and Zhongmu County had the fastest growth rate and the most obvious increase.The flood risk of Zhengzhou City has been expanding with the development of urbanization.The method is adapted to Zhengzhou City and will have good adaptability in other research areas,and its risk assessment results can provide a scientific reference for urban flood management personnel.In the future,the accuracy of flood risk assessment can be further improved by promoting the accuracy of basic data and reasonably determining the weight values of index factors.The risk zoning map can better reflect the risk distribution and provide a scientific basis for early warning of flood prevention and drainage.

The multi-dimension RSA and its low exponent security

Using a well-known result of polynomial over the finite field , we show that the Euler-Fermat theorem holds in N[ x]. We present a multi-dimension RSA cryptosystem and point out that low exponent algorithm of attacking RSA is not suitable for the multi-dimension RSA. Therefore, it is believed that the security of the new cryptosystem is mainly based on the factorization of large integers.

POINTWISE ESTIMATE OF SOLUTIONS OF ISENTROPIC NMIER-STOKES EQUATIONS IN EVEN SPACE-DIMENSION

This paper is concerned with the dissipation of solutions of the isentropic Navier-Stokes equations in even and bigger than two multi-dimensions. Pointwise estimates of the time-asymptotic shape of the solutions are obtained and the generalized Huygan's principle is exhibited. The approch of the paper is based on the detailed analysis of the Green function of Iinearized system. This is used to study the coupling of nonlinear diffesion waves.

ATMP中冲正缓存设计及实现

针对ATMP系统中日益增长的业务规模和需求而导致的性能瓶颈问题,提出了基于multi-index的缓存机制。该机制提供快速的内存数据关联和存储。相比共享缓存加消息队列的方式,该缓存提高了业务扩充的灵活度和效率。经过仿真和压力测试,该缓存运行鲁棒性高,在并发业务下性能良好。

Comprehensive Assessment of Urbanization Coordination:A Case Study of Jiangxi Province, China

In order to make assessment on urbanization coordination, we developed a comprehensive model by integrating entropy weight method(EWM), coupling degree model(CDM), coupling coordination degree model(CCDM), multi-index grading method(MIGM) and Remote Sensing & Geographic Information System(RS & GIS) technology. Then we applied this integrated model to a case study in Jiangxi Province, China. Our study finds that: 1) EWM, CDM and CCDM can evaluate the temporal dynamic of urbanization. Urbanization process of Jiangxi Province can be divided into three periods, the stable development period(1990–2001), the accelerated development period(2002–2009) and the rapid development period(2010–2015). Coordinated development of urbanization in Jiangxi Province can be divided into two phases, an increasingly coordinated phase(1990–2003) and an increasingly incongruous phase(2003–2015). The state transition was due to low development rate of population urbanization. 2) RS & GIS technology is an effective tool for detecting urban growth. Urban construction land area of Jiangxi Province increased from 615.8 km^2 in 1990 to 2896.8 km^2 in2015, and the per capita urban construction land area(PCUCLA) reached 122.9 m^2, with the maximum value of 343 m^2 in Gongqingcheng City. 3) MIGM and RS & GIS technology can analyze spatial difference of urbanization. There is a significant spatial difference in socioeconomic development at county scale, with the maximum value six times the minimum value for both PCUCLA and per capita GDP in 2015. Population urbanization lag and excessive land use are the main reasons for uncoordinated urbanization. There were 15 counties with a lag in demographic urbanization and 33 counties where PCUCLA exceeded the national standard in 2015, among which 20 exceeded the national standard of PCUCLA by 50%(≥165 m^2). Since there are significant spatio-temporal differences in urbanization, it is necessary to carry out a comprehensive assessment to facilitate differential urbanization strategy making.

Switching mechanism and optimisation research on a pressure-attitude adaptive adjusting coal seam water jet slotter

To investigate the attitude-switching mechanisms of existing jet slotters,which integrate drilling,punching and slotting operations,and to improve its fracture ability,we used the power bond diagram theory to analyse the dynamic flow pressure,and force of slotters.A mathematical model was developed for the dynamic characteristics of slotter systems.Furthermore,to study the effect of the main characteristic parameters on the ability of the nozzle to erode sandstone,multi-orthogonal experiments were carried out.And the optimised slots were applied in later practical operations.The research results show that the inlet fluid passed through the time-varying orifice to generate pressure differential thrust,which overcame the spring force,pushed the valve core to open the side nozzle,and closed the rear cavity channel thereby realising the switch of the slotter attitude.An optimal plan was established to balance the diameter,depth,and volume of punching,and a rock-breaking plan was developed for the slotter.Subsequently,the optimised water jet slotter was practically used in coal seam gas drainage.Compared with conventional dense drilling,water jet slotting technology significantly improves the ability,efficiency,and effect of increasing the permeability of the coal seam.

Optics System Design of Microwave Imaging Reflectometry for the EAST Tokamak

A front-end optics system has been developed for the EAST microwave imaging reflectometry for 2D density fluctuation measurement.Via the transmitter optics system,a combination of eight transmitter beams with independent frequencies is employed to illuminate wide poloidal regions on eight distinct cutoff layers.The receiver optics collect the reflected wavefront and project them onto the vertical detector array with 12 antennas.Utilizing optimized Field Curvature adjustment lenses in the receiver optics,the front-end optics system provides a flexible and perfect matching between the image plane and a specified cutoff layer in the plasma,which ensures the correct data interpretation of density fluctuation measurement.

基于动态综合评价模型的街区型住区开放对城市交通拥堵影响的研究（英文）

The growing use of vehicles with the development of China brings greater pressure on the existing road traffic network. Based on the domestic and international research experiences and the domestic congestion situations, this paper selected six indicators that affect the traffic conditions. As each single indicator cannot reflect the detailed traffic quality separately, the dynamic comprehensive evaluation principle is adopted.Then we used the principle of "Variation Driven" to determine the weight vector of each sub-indicator, and established a multi-indicator comprehensive evaluation system through the dynamic weight of each sub-indicator. Finally, the rationality and feasibility of the system is demonstrated by case analysis. This provides a strong theoretical foundation and basis to mitigate traffic congestion.

Forming limits under multi-index constraints in NC bending of aluminum alloy thin-walled tubes with large diameters

With increasing diameters of aluminum alloy thin-walled tubes (AATTs), the tube forming limits, i.e. the minimum bending factors, and their predictions under multi-index constraints including wrinkling, thinning and flattening have been being a key problem to be urgently solved for improving tube forming potential in numerical control (NC) bending processes of AATTs with large diameters. Thus in this paper, a search algorithm of the forming limits is put forward based on a 3D elastic-plastic finite element (FE) model and a wrinkling energy prediction model for the bending processes under axial compression loading (ACL) or not. This algorithm enables to be considered the effects of process parameter combinations including die, friction parameters on the multi-indices. Based on this algorithm, the forming limits of the different size tubes are obtained, and the roles of the process parameter combinations in enabling the limit bending processes are also revealed. The followings are found: the first, within the appropriate ranges of friction and clearances between the different dies and the tubes enabling the bending processes with smaller bending factors, the ACL enables the tube limit bending processes after a decrease of the mandrel ball thickness and diameters; then, without considering the effects of the tube geometry sizes on the tube constitutive equations, the forming limits will be decided by the limit thinning values for the tubes with diameters smaller than 80 mm, while the wrinkling for the tubes with diameters no less than 80 mm. The forming limits obtained from this algorithm are smaller than the analytical results, and reduced by 57.39%; the last, the roles of the process parameter combinations in enabling the limit bending processes are verified by experimental results.

MIX-RS:A Multi-Indexing System Based on HDFS for Remote Sensing Data Storage

A large volume of Remote Sensing(RS)data has been generated with the deployment of satellite technologies.The data facilitate research in ecological monitoring,land management and desertification,etc.The characteristics of RS data(e.g.,enormous volume,large single-file size,and demanding requirement of fault tolerance)make the Hadoop Distributed File System(HDFS)an ideal choice for RS data storage as it is efficient,scalable,and equipped with a data replication mechanism for failure resilience.To use RS data,one of the most important techniques is geospatial indexing.However,the large data volume makes it time-consuming to efficiently construct and leverage.Considering that most modern geospatial data centres are equipped with HDFS-based big data processing infrastructures,deploying multiple geospatial indices becomes natural to optimise the efficacy.Moreover,because of the reliability introduced by high-quality hardware and the infrequently modified property of the RS data,the use of multi-indexing will not cause large overhead.Therefore,we design a framework called Multi-IndeXing-RS(MIX-RS)that unifies the multi-indexing mechanism on top of the HDFS with data replication enabled for both fault tolerance and geospatial indexing efficiency.Given the fault tolerance provided by the HDFS,RS data are structurally stored inside for faster geospatial indexing.Additionally,multi-indexing enhances efficiency.The proposed technique naturally sits on top of the HDFS to form a holistic framework without incurring severe overhead or sophisticated system implementation efforts.The MIX-RS framework is implemented and evaluated using real remote sensing data provided by the Chinese Academy of Sciences,demonstrating excellent geospatial indexing performance.

ANALYSIS OF MULTI-INDEX MONTE CARLO ESTIMATORS FOR A ZAKAI SPDE

In this article, we propose a space-time Multi-Index Monte Carlo （MIMC） estimator for a one-dimensional parabolic stochastic partial differential equation （SPDE） of Zakai type. We compare the complexity with the Multilevel Monte Carlo （MLMC） method of Giles and Reisinger （2012）, and find, by means of Fourier analysis, that the MIMC method： （i） has suboptimal complexity of 0（ε^-21 ｜ogε｜） for a root mean square error （RMSE） z if the same spatial discretisation as in the MLMC method is used; （ii） has a better complexity of 0（ε^-21 ｜ogε｜） if a carefully adapted discretisation is used; （iii） has to be adapted for non-smooth functionals. Numerical tests confirm these findings empirically.

A bioinspired path planning approach for mobile robots based on improved sparrow search algorithm

In this paper,a bioinspired path planning approach for mobile robots is proposed.The approach is based on the sparrow search algorithm,which is an intelligent optimization algorithm inspired by the group wisdom,foraging,and anti-predation behaviors of sparrows.To obtain high-quality paths and fast convergence,an improved sparrow search algorithm is proposed with three new strategies.First,a linear path strategy is proposed,which can transform the polyline in the corner of the path into a smooth line,to enable the robot to reach the goal faster.Then,a new neighborhood search strategy is used to improve the fitness value of the global optimal individual,and a new position update function is used to speed up the convergence.Finally,a new multi-index comprehensive evaluation method is designed to evaluate these algorithms.Experimental results show that the proposed algorithm has a shorter path and faster convergence than other state-ofthe-art studies.

Research on Next-Generation Internet Architecture

The primary problem during the evolvement of next-generation Internet is the contradiction between growing requirements for Internet and the insufficient development of network theory and technology. As the fundamental principles to guide the developing direction of Internet, the study of Internet architecture is always a focus in the research community. To address the core issue of network scalability, we propose multi-dimension scalable architecture of next-generation Internet, the main idea of which is to extend the single-dimension scalability of traditional Internet on interconnection to multi-dimension scalability of next-generation Internet. The multi-dimension scalability is composed of scale-scalability, performance-scalability, security-scalability, function-scalability, and service-scalability. We suggest five elements, namely, IPv6, authentic IPv6 addressing, scalable processing capacity of routers, end-to-end connectionless Quality-of-Service control, and 4over6 mechanism to realize the multi-dimension scalability. The current research results show that the multi-dimension scalable architecture composed of these five elements will bring great influence on next-generation Internet.

Improved HHO algorithm based on good point set and nonlinear convergence formula

Harris hawks optimization(HHO)algorithm is an efficient method of solving function optimization problems.However,it is still confronted with some limitations in terms of low precision,low convergence speed and stagnation to local optimum.To this end,an improved HHO(IHHO)algorithm based on good point set and nonlinear convergence formula is proposed.First,a good point set is used to initialize the positions of the population uniformly and randomly in the whole search area.Second,a nonlinear exponential convergence formula is designed to balance exploration stage and exploitation stage of IHHO algorithm,aiming to find all the areas containing the solutions more comprehensively and accurately.The proposed IHHO algorithm tests 17 functions and uses Wilcoxon test to verify the effectiveness.The results indicate that IHHO algorithm not only has faster convergence speed than other comparative algorithms,but also improves the accuracy of solution effectively and enhances its robustness under low dimensional and high dimensional conditions.

Theoretical research progress in new-generation Internet architecture

Internet has become the most important information infrastructure supporting modern socio-economic development, social progress and technological Innovation. Invented 30 years ago, today Internet is facing increasingly severe technical challenges. This paper introduces the progress of the major international newgeneration Internet research plans; analyzes its basic characteristics and the principal contradictions during the development; detsiledly introduces the research carried out by 973 Project ＂Research of Future Internet Architecture＂ on the key scientific issues of new-generation Internet architecture and its latest research results; and looks to the future of the research-focus faced with the new situations of the basic research of new-generation Internet architecture as well as the new demands of innovative applications on Internet architecture.