地理学:计量运动的失败与分形研究的崛起

论述地理学计量运动盛衰的前因后果和地理分形研究发展的来龙去脉，说明只有借助分形几何学，地理学的计量化才能成功。文章指出，未来地理学的主流将是分形地理学。

Fast global motion estimation and moving object extraction algorithm in image sequences

A novel and effective approach to global motion estimation and moving object extraction is proposed. First, the translational motion model is used because of the fact that complex motion can be decomposed as a sum of translational components. Then in this application, the edge gray horizontal and vertical projections are used as the block matching feature for the motion vectors estimation. The proposed algorithm reduces the motion estimation computations by calculating the onedimensional vectors rather than the two-dimensional ones. Once the global motion is robustly estimated, relatively stationary background can be almost completely eliminated through the inter-frame difference method. To achieve an accurate object extraction result, the higher-order statistics （HOS） algorithm is used to discriminate backgrounds and moving objects. Experimental results validate that the proposed method is an effective way for global motion estimation and object extraction.

现代地理学基本理论及可持续发展研究

地理学是一门古老的科学,同时也是一门年轻的科学,本文通过对古、近代及现代地理学基本理论思想的研究,提出可持续发展是未来地理学研究的新生面。

基于STM32的“智能可穿戴设备”课程实验教学平台设计

针对生物医学工程专业"智能可穿戴设备技术"课程,设计了一款能够二次开发的人体生理参数实验教学平台。该文分析了平台架构,对光电容积法测血氧脉搏原理和加速度传感器计步原理进行介绍,并对开发平台步态及心率准确性进行测试,准确率均达到95%以上,实现了预期功能。

Study of virtual reality for mild cognitive impairment:A bibliometric analysis using CiteSpace

Objectives Non-invasive and low-cost virtual reality(VR)technology is important for early evaluation and intervention in mild cognitive impairment(MCI).This study aimed to demonstrate the current status of overseas and domestic research as well as the focus and frontier of VR technology among individuals with MCI through a bibliometric analysis.Methods Studies from the core collection of Web of Science™between 1995 and 2020 were used;furthermore,CiteSpace 5.7 R3 was utilized to analyse information on authors/cited authors,keywords,burst words,and cited references.Results In total,230 publications were identified.Most studies were published in the USA(45 publications)and Italy(41 publications),where Guiseppe Riva ranks first(14 publications),and Tarnanas I is the author with the highest centrality(0.44).The hot topics in VR applications in the MCI population are‘physical activity,’‘people,’‘single-blind,’‘disease,’‘walking,’‘technology,’‘working memory,’and‘risk’in recent years.The keyword‘mild cognitive impairment’has attracted extensive attention since 2012,showing the strongest citation outbreak(8.28).The clustering results of the literature show the research types and emerging trends,including‘exergame,’‘serious games,’‘spatial navigation,’‘activities of daily living,’‘exercise,’‘enriched environment’and‘wayfinding.‘Conclusions Cognitive assessment and nonpharmacological intervention research on patients with MCI have become the focus of dementia prevention in recent years.Virtual technology,combined with traditional methods such as exercise therapy,provides new ideas for innovative cognitive evaluation and cognitive intervention.

Probability modeling for robustness of multivariate LQG designing based on ship lateral motion

The robustness of LQG designing for latitudinal movement of ship is mainly discussed, when its hydrodynamic parameters fluctuate around criterion value at random on the proportional distributing. When a given ship state at the speed of 18 kn and the course of 45° under Rank 5 state of sea, and the hydrodynamic parameters of the ship fluctuate at random on the proportional distributing with a range of ± 10% , ± 20% , ± 30% , the robustness of muhivariate LQG designing for ship is analyzed with applying the probability modeling of relative controlling effect, The result of simulating shows that when the hydrodynamic parameters of ship fluctuates the relative controlling effect of the LQG designing submit to normal distribution and the mean value of relative controlling effect has no remarkable changes comparing to that without perturbation of hydrodynamic parameter,

A framework for quantifying properties of 3-dimensional movement-based signals

Understanding how signal properties are optimized for the reliable transmission of information requires accurate de- scription of the signal in time and space. For movement-based signals where movement is restricted to a single plane, measure- ments from a single viewpoint can be used to consider a range of viewing positions based on simple geometric calculations. However, considerations of signal properties from a range of viewing positions for movements extending into three-dimensions （3D） are more problematic. We present here a new framework that overcomes this limitation, and enables us to quantify the extent to which movement-based signals are view-specific. To illustrate its application, a Jacky lizard tail flick signal was filmed with synchronized cameras and the position of the tail tip digitized for both recordings. Camera aligmnent enabled tl^e construction of a 3D display action pattern profile. We analyzed the profile directly and used it to create a detailed 3D animation. In the virtual environment, we were able to film the same signal from multiple viewing positions and using a computational motion analysis algorithm （gradient detector model） to measure local image velocity in order to predict view dependent differences in signal properties. This approach will enable consideration of a range of questions concerning movement-based signal design and evolu- tion that were previously out of reach [Current Zoology 56 （3）： 327-336, 2010].

Designing Socially Sound Poultry FarmingmMatching Hen Ethology, Farm Management and Landscape Quality

In order to receive a licence to produce, poultry farmers have to take into account societal demands, among others： animal welfare, healthy working conditions for the workers and landscape quality. A way to reach a combination of these goals is to create a design for the poultry house and outdoor run. We propose a methodology based on five steps, which enables us to create a design that takes into consideration societal demands and that can be tested on its effects. These five steps are： 1. Giving a theoretical background on the societal demands （hen ethology, farm management and landscape quality） and based on this; 2. Giving a set of design criteria. 3. Describing the cttrrent state of the farm, in order to know its current qualities, 4. Making a design of the farm using the sets of criteria as guiding principle. 5. Reflecting on the design, to show whether the different criteria can be combined and where compromises are needed. A case study on an organic farm in the centre of the Netherlands showed that hen welfare, farm management and landscape quality can be improved together, although some measures do not add to all design criteria. Especially the effect on landscape quality and farm management is variable： the latter is also depending on the personal motivation of the farmer.

A complexity-scalable software-based MPEG-2 video encoder

With the development of general-purpose processors (GPP) and video signal processing algorithms, it is possible to implement a software-based real-time video encoder on GPP, and its low cost and easy upgrade attract developers' interests to transfer video encoding from specialized hardware to more flexible software. In this paper, the encoding structure is set up first to support complexity scalability; then a lot of high performance algorithms are used on the key time-consuming modules in coding process; finally, at programming level, processor characteristics are considered to improve data access efficiency and processing parallelism. Other programming methods such as lookup table are adopted to reduce the computational complexity. Simulation results showed that these ideas could not only improve the global performance of video coding, but also provide great flexibility in complexity regulation.

Influence of age in estimating maximal oxygen uptake

Objective To assess the influence of age on the error of estimate （EE） of maximal oxygen uptake （VO2max） using sex and population specific-equations in cycle ergometer exercise testing, since estimated VO2 max is associated with a substantial EE, often exceeding 20%, possibly due to intrinsic variability of mechanical efficiency. Methods 1850 adults （68% men）, aged 18 to 91 years, underwent maximal cycle ergometer cardiopulmonary exercise testing. Cardiorespiratory fitness （CRF） was assessed relative to sex and age [younger （18 to 35 years）, middle-aged （36 to 60 years） and older （〉 60 years）]. VO2max [mL.（kg.min）-1] was directly measured by assessment of gas exchange and estimated using sex and population specific-equations. Measured and estimated values of VO2max and related EE were compared among the three age- and sex-specific groups. Results Directly measured VO2max of men and women were 29.5 ± 10.5 mL.（kg.min）-1 and 24.2 ± 9.0 mL.（kg·min） -1 （P 〈 0.01）. EE [mL·（kg·min）-1] and percent errors （%E） for men and women had similar values, 0.5 ± 3.2 and 0.4 ± 2.9 mL·（kg·min）-1, and -0.8 ± 13.1% and -1.7 ± 15.4% （P 〉 0.05）, respectively. EE and %E for each age-group were, respectively, for men： younger = 1.9 ± 4.1 mL·（kg·min）-1 and 3.8 ± 10.5%, middle-aged = 0.6 ± 3.1 mL.（kg·min）-1 and 0.4 ± 10.3%, older = -0.2 ± 2.7 mL·（kg·min） -1 and -4.2 ± 16.6% （P 〈 0.01）; and for women： younger = 1.2 ± 3.1 mL.（kg.min）-1 and 2.7 ±10.0%, middle-aged = 0.7 ± 2.8 mL·（kg·min）-1 and 0.5 ± 11.1%, older = -0.8 ± 2.3 mL-（kg·min）-1 and -9.5 ± 22.4% （P 〈 0.01）. Conclusion VO2max were underestimated in younger age-groups and were overestimated in older age groups. Age significantly influences the magnitude of the EE of VO2max in both men and women and should be considered when CRF is estimated using population specific equations, rather than directly measured.

Video Image Block-matching Motion Estimation Algorithm Based on Two-step Search

Aiming at the shortcoming that certain existing blockingmatching algorithrns, such as full search, three-step search, and dia- mond search algorithms, usually can not keep a good balance between high acoaracy and low computational complexity, a block-maching motion estimation algorithm based on two-step search is proposed in this paper. According to the fact that the gray values of adjacent pixels will not vary fast, the algorithm employs an interlaced search pattem in the search window to estimate the motion vector of the objectblock. Simulation and actual experiments demanstrate that the proposed algmithm greatly outperforms the well-known three-step search and dianond search algoritlam, no matter the motion vector is large or small. Comparedc with the full search algorithm, the proposed one achieves similar peffomance but requires much less computation, therefore, the algorithm is well qualified for real-time video image processing.

Unsupervised Spatio-Temporal Segmentation for Extracting Moving Objects in Video Sequences

Extraction of moving objects is an important and fundamental research topic for many video applications. This paper addresses an unsupervised spatio-temporal segmentation scheme to extract moving objects from video sequences.The temporal segmentation localizes moving objects by comparing the motion vector of each block in each frame with the corresponding global motion vector estimated by an outlier rejection(OR) based method.Furthermore,the temporal compensation utilizing the temporal coherence of moving objects is considered in the temporal segmentation to solve the temporarily stopping problem.The detected moving regions usually have discontinuous boundaries and some holes.These regions are then compensated in the spatial domain. In the spatial segmentation,the watershed algorithm considering the global information improves the accuracy of segmentation in the spatial domain.The modified mean filter is presented to suppress some minima.By using a fusion module,moving objects are extracted.Experiments on various sequences have successfully demonstrated the validity of the proposed scheme.

Extremes of Shepp statistics for fractional Brownian motion

Define the incremental fractional Brownian field with parameter H ∈ （0, 1） by ZH（τ, s） = BH（s-＋τ） - BH（S）, where BH（s） is a fractional Brownian motion with Hurst parameter H ∈ （0, 1）. We firstly derive the exact tail asymptoties for the maximum MH＊（T） = max（τ,s）∈[a,b]×[0,T] ZH（τ, s）/τH of the standardised fractional Brownian motion field, with any fixed 0 〈 a 〈 b 〈 ∞ and T 〉 0; and we, furthermore, extend the obtained result to the ease that T is a positive random variable independent of {BH（s）, s ≥ 0}. As a by-product, we obtain the Gumbel limit law for MH＊r（T） as T →∞.

保持健康

你喜欢和小伙伴在公园里玩猫捉老鼠的游戏吗？你们追啊、躲啊、喊啊、笑啊，不一会儿呼吸就变快了，身上也觉得暖烘烘的。运动就是这么有趣，它能让你感到快乐，还能帮你保持健康。

Optimal design and experimental measurement of the subharmonic characterizations of encapsulated microbubble

Based on a theoretical motion equation of encapsulated microbubbles within an ultrasound field, the subharmonic characterizations of microbubbles are optimally designed and analyzed by a computer aided design system. The effects of size, shell elasticity and acoustic pressure on subharmonic response of microbubbles are calculated theoretically to obtain the optimal parameters for nondestructive subharmonic imaging. In addition, microbubbles with different shell elasticity are prepared, and their subharmonic responses are measured in vitro. The results of theoretical calculation and acoustic measurement show that good subharmonic enhancement can be obtained by using the encapsulated microbubbles with the mean size of 3 μm, which were prepared from the surfactant solution with the proper ratio of shell material. It is also shown that the best operating acoustic pressure is 200 to 400 kPa for nondestructive subharmonic imaging based on such kind of microbubbles.