Heterogeneous information phase space reconstruction and stability prediction of filling body–surrounding rock combination

Traditional research believes that the filling body can effectively control stress concentration while ignoring the problems of unknown stability and the complex and changeable stress distribution of the filling body–surrounding rock combination under high-stress conditions.Current monitoring data processing methods cannot fully consider the complexity of monitoring objects,the diversity of monitoring methods,and the dynamics of monitoring data.To solve this problem,this paper proposes a phase space reconstruction and stability prediction method to process heterogeneous information of backfill–surrounding rock combinations.The three-dimensional monitoring system of a large-area filling body–surrounding rock combination in Longshou Mine was constructed by using drilling stress,multipoint displacement meter,and inclinometer.Varied information,such as the stress and displacement of the filling body–surrounding rock combination,was continuously obtained.Combined with the average mutual information method and the false nearest neighbor point method,the phase space of the heterogeneous information of the filling body–surrounding rock combination was then constructed.In this paper,the distance between the phase point and its nearest point was used as the index evaluation distance to evaluate the stability of the filling body–surrounding rock combination.The evaluated distances(ED)revealed a high sensitivity to the stability of the filling body–surrounding rock combination.The new method was then applied to calculate the time series of historically ED for 12 measuring points located at Longshou Mine.The moments of mutation in these time series were at least 3 months ahead of the roadway return dates.In the ED prediction experiments,the autoregressive integrated moving average model showed a higher prediction accuracy than the deep learning models(long short-term memory and Transformer).Furthermore,the root-mean-square error distribution of the prediction results peaked at 0.26,thus outperforming the no-prediction method in 70%of the cases.

Physics of Clocks in Absolute Space-Time

20th century physics experimentally established beyond doubt the fact that moving clocks read differently from “static” clocks. This fact is typically interpreted as support for special relativity. On the other hand, the same century produced proof that clocks at various locations in the gravitational field also read differently, and this fact is explained by general relativity, which is, in general, not Lorentz transformable. This paper establishes a common framework for the physics of clocks in these different situations.

A New Generalized Complex Orthogonal Space-Time Block Codes

Recent research challenges in the wireless communication include the usage of diversity and efficient coding to improve data transmission quality and spectral efficiency. Space diversity uses multiple transmitting and/or receiving antennas to create independent fading channels without penalty in bandwidth efficiency. Space-time block coding is an encoding scheme for communication over Rayleigh fading channels using multiple transmitting antennas. Space-time block codes from complex orthogonal designs exist only for two transmitting antennas. This paper generalizes a new complex orthogonal space-time block code for four transmitting antennas, whose decoding complexity is very low. Simulations show that the generalized complex orthogonal space-time block code has low bit error rate, full rate and possibly large diversity.

Gravitation in Flat Space-Time and General Relativity

A covariant theory of gravitation in flat space-time is stated and compared with general relativity. The results of the theory of gravitation in flat space-time and of general relativity agree for weak gravitational fields to low approximations. For strong fields the results of the two theories deviate from one another. Flat space-time theory of gravitation gives under some natural assumptions non-singular cosmological models with a flat space. The universe contracts to a positive minimum and then it expands for all times. Shortly, after the minimum is reached, the cosmological models of two theories approximately agree with one another if models in general relativity with zero curvature are considered. A flat space is proved by experiments.

A Novel Staggered Semi-implicit Space-Time Discontinuous Galerkin Method for the Incompressible Navier-Stokes Equations

A new high-order accurate staggered semi-implicit space-time discontinuous Galerkin(DG)method is presented for the simulation of viscous incompressible flows on unstructured triangular grids in two space dimensions.The staggered DG scheme defines the discrete pressure on the primal triangular mesh,while the discrete velocity is defined on a staggered edge-based dual quadrilateral mesh.In this paper,a new pair of equal-order-interpolation velocity-pressure finite elements is proposed.On the primary triangular mesh(the pressure elements),the basis functions are piecewise polynomials of degree N and are allowed to jump on the boundaries of each triangle.On the dual mesh instead(the velocity elements),the basis functions consist in the union of piecewise polynomials of degree N on the two subtriangles that compose each quadrilateral and are allowed to jump only on the dual element boundaries,while they are continuous inside.In other words,the basis functions on the dual mesh arc built by continuous finite elements on the subtriangles.This choice allows the construction of an efficient,quadrature-free and memory saving algorithm.In our coupled space-time pressure correction formulation for the incompressible Navier-Stokes equations,the arbitrary high order of accuracy in time is achieved through tire use of time-dependent test and basis functions,in combination with simple and efficient Picard iterations.Several numerical tests on classical benchmarks confirm that the proposed method outperforms existing staggered semi-implicit space-time DG schemes,not only from a computer memory point of view,but also concerning the computational time.

A Fractal Menger Sponge Space-Time Proposal to Reconcile Measurements and Theoretical Predictions of Cosmic Dark Energy

The 95.5 percent of discrepancy between theoretical prediction based on Einstein’s theory of relativity and the accurate cosmological measurement of WMAP and various supernova analyses is resolved classically using Newtonian mechanics in conjunction with a fractal Menger sponge space proposal. The new energy equation is thus based on the familiar kinetic energy of Newtonian mechanics scaled classically by a ratio relating our familiar three dimensional space homology to that of a Menger sponge. The remarkable final result is an energy equation identical to that of Einstein’s E=mc2 but divided by 22 so that our new equation reads as . Consequently the energy Lorentz-like reduction factor of percent is in astonishing agreement with cosmological measurements which put the hypothetical dark energy including dark matter at percent of the total theoretical value. In other words our analysis confirms the cosmological data putting the total value of measured ordinary matter and ordinary energy of the entire universe at 4.5 percent. Thus ordinary positive energy which can be measured using conventional methods is the energy of the quantum particle modeled by the Zero set in five dimensions. Dark energy on the other hand is the absolute value of the negative energy of the quantum Schrodinger wave modeled by the empty set also in five dimensions.

An accurate and efficient space-time Galerkin spectral method for the subdiffusion equation

In this paper, we design and analyze a space-time spectral method for the subdiffusion equation.Here, we are facing two difficulties. The first is that the solutions of this equation are usually singular near the initial time. Consequently, traditional high-order numerical methods in time are inefficient. The second obstacle is that the resulting system of the space-time spectral approach is usually large and time-consuming to solve. We aim at overcoming the first difficulty by proposing a novel approach in time, which is based on variable transformation techniques. Suitable ψ-fractional Sobolev spaces and a new variational framework are introduced to establish the well-posedness of the associated variational problem. This allows us to construct our space-time spectral method using a combination of temporal generalized Jacobi polynomials(GJPs) and spatial Legendre polynomials. For the second difficulty, we propose a fast algorithm to effectively solve the resulting linear system. The fast algorithm makes use of a matrix diagonalization in space and QZ decomposition in time. Our analysis and numerical experiments show that the proposed method is exponentially convergent with respect to the polynomial degrees in both space and time directions, even though the exact solution has very limited regularity.

Surplus Space Method: A New Numerical Model for Prediction of Shallow-seated Magmatic Bodies

Based on the data of field measurement and drilling in the Tongling area, a series of numerical simulations are carried out by using the 'Surplus Space Method' (SSM), which is first put forward in this paper and applied to predict the shallow-seated magmatic bodies. The results of the numerical simulations show the existence and the 3-D shape of a conical magmatic structure at a depth of-1000 m beneath the center of the area: its top offsets southwards and bifurcates to several branches, while its lower part stretches northeastwards and contracts rapidly to a point at about -1000 m depth. This point is reckoned to be a 'sink' of magma system, transferring ore materials and heat energy from the deep magma chamber to the sub-surface apophyses. The preliminary application of the SSM proves that it may be developed as a new detection means for determining the existence of shallow-seated magmatic bodies and analyzing their three-dimensional features.

Deer Body Adaptive Threshold Segmentation Algorithm Based on Color Space

In large-scale deer farming image analysis,K-means or maximum between-class variance(Otsu)algorithms can be used to distinguish the deer from the background.However,in an actual breeding environment,the barbed wire or chain-link fencing has a certain isolating effect on the deer which greatly interferes with the identification of the individual deer.Also,when the target and background grey values are similar,the multiple background targets cannot be completely separated.To better identify the posture and behaviour of deer in a deer shed,we used digital image processing to separate the deer from the background.To address the problems mentioned above,this paper proposes an adaptive threshold segmentation algorithm based on color space.First,the original image is pre-processed and optimized.On this basis,the data are enhanced and contrasted.Next,color space is used to extract the several backgrounds through various color channels,then the adaptive space segmentation of the extracted part of the color space is performed.Based on the segmentation effect of the traditional Otsu algorithm,we designed a comparative experiment that divided the four postures of turning,getting up,lying,and standing,and successfully separated multiple target deer from the background.Experimental results show that compared with K-means,Otsu and hue saturation value(HSV)+K-means,this method is better in performance and accuracy for adaptive segmentation of deer in artificial breeding scenes and can be used to separate artificially cultivated deer from their backgrounds.Both the subjective and objective aspects achieved good segmentation results.This article lays a foundation for the effective identification of abnormal behaviour in sika deer.

STUDY ON DYNAMICS, STABILITY AND CONTROL OF MULTI-BODY FLEXIBLE STRUCTURE SYSTEM IN FUNCTIONAL SPACE

The dynamics, stability and control problem of a kind of infinite dimensional system are studied in the functional space with the method of modern Mathematics. First, the dynamical control model of the distributed parameter system with multi-body flexible and multi-topological structure was established which has damping, gyroscopic parts and constrained damping. Secondly, the necessary and sufficient condition of controllability and observability, the stability theory and asymptotic property of the system were obtained. These results expand the theory of the field about the dynamics and control of the system with multi-body flexible structure, and have important engineering significance.

Silver nitrate mimicking a foreign body in the pharyngeal mucosal space

Silver nitrate is sometimes used as a means of chemicalcauterization for control of minor bleeding and management of hypergranulation tissue following bedside head and neck procedures. There are only few reports available on the imaging appearance of silver nitrate and its potential to mimic a foreign body. We report a case of a patient presenting with dysphagia, odynophagia, and fever following dental work who had a peritonsillar incision and drainage for treatment of a deep neck space infection. During the procedure, silver nitrate was applied to halt the bleeding. Patient was subsequently transferred to another institution. Since the patient was not showing significant clinical improvement on antibiotic therapy, a computed tomography(CT) scan was performed demonstrating a hyperdense structure lodged in the pharyngeal mucosal space in the oropharynx and soft palate that was mistaken for a foreign body such as bone. Silver nitrate can have density similar to bone but does not have the normal architecture of bone with cortex and marrow on CT. Familiarity with the appearance of silver nitrate on CT, lack of bone architecture, and proper documentation and communication of the use of silver nitrate to the consultant radiologist and medical personnel could help avoid misdiagnosis and potentially unnecessary surgical exploration.

中国风景园林理论体系建设回顾与展望

【目的】梳理20世纪80年代以来中国风景园林理论体系研究的内容及发展脉络,综合评析风景园林理论体系建设的发展水平,以期为进一步推动风景园林理论体系建设提供思路,从而促进学科理论、方法和技术的发展。【方法】从理论体系建构的不同视角或维度出发,归纳、比较和反思中国风景园林理论体系建设的途径、思路和方法,发掘看待风景园林理论与实践相关现象的不同方式。【结果】辨别和剖析了传统体系、设计体系、空间体系、知识体系、学科体系5种理论体系的异同与关联,以及对学科理论发展的影响和作用,并剖析了学科理论发展过程中存在的诸多问题。【结论】理论体系的建构能够促进对学科内在和外在关系的思考,可视为中国风景园林学科与专业理论发展的结晶,借此把握学科理论的发展动向,并以开放式的答案与认知面对当前的困境。

山水何以可游?——论山水画中的形而下之道及其超越性

山水画之所以“可居”“可游”,因其有道,山水之道既体现为形而上的哲思,也呈现为画面上的逶迤细路。它并非某种凸显于画面有形体、有细节的视觉对象,却常呈现为被山水树石等物装裱的虚空。五代北宋时期的全景山水和我们的身体图式相契合,为观者“步入”山水画之中开了方便之门,也奠定了中国山水画的空间知觉方式。画面路径多开始于画幅下端并向上方横斜蜿蜒,在观者的知觉中被解读为向画面深处延展,散点透视则营造了一个动态知觉过程,使得“游观”成为可能。山水画中的路形态多样,但其在视觉上多显现为深远山水意境中的“细路”。“三远”图式即意味着画面上的道路,需要被呈现为“窄”和“细”的形态,否则便无法凸显咫尺万里之势,与“细路”相对应的是“独往”,呼应着中国传统哲学与诗学中的“独往”,从而获得与天地精神相往来的超越。

基于对偶四元数的多体系统动力学建模和控制

空间机械臂的在轨作业是当前空间在轨服务中应用最为广泛的技术之一,然而,机械臂在操作过程中漂浮基座与臂体之间的位姿耦合效应极为显著,这给控制系统设计带来了新挑战.针对多刚体系统的位姿一体化建模与控制问题,文章改进了基于对偶四元数的位姿一体化建模和控制方法,使之可以应用于多刚体系统.该方法不仅能够精确描述复杂的力学关系,还能够在统一的数学框架中有效地处理位姿耦合问题,这为后续设计姿轨一体化的控制系统提供了极大的便利.首先,基于铰链模型建立了对偶四元数形式的铰链和臂体之间的速度和加速度递推关系,然后,利用铰链和臂体间力-力矩传递关系建立了递推形式的逆向动力学方程,为了便于控制系统设计与分析,随后推导建立了矩阵形式的位姿一体化的正向动力学方程.然后针对推进器和控制力矩陀螺讨论了具体的执行机构的动力学建模问题,并分别讨论了机械臂和漂浮基座的位姿一体化控制问题.最后,对一个6自由度机械臂和漂浮基座的组合体进行了动力学建模和控制仿真,动力学仿真的结果证明了所提动力学建模方法的正确性,控制仿真表明控制系统能较快地抵消机械臂运动对基座产生的干扰力和干扰力矩,证明了所提控制方法的有效性和可行性.

基于空间向量模长的青年女性腰腹臀部形态分类与判别

为实现女体三维曲面的分类与判别,提高裤装的合体性,提出一种基于空间向量模长表征腰腹臀部形态并进行体型分类的方法。获取323名18~25岁青年女性的三维点云数据,提取腰腹臀部10层横截面曲线,以臀围质心为原点重建点云坐标系,通过欧式距离计算130个特征点的空间向量模长,构建表征人体曲面形态的模长矩阵。引入拉普拉斯特征映射降维获取18个本征维度,采用K-means聚类,运用随机森林算法建立青年女性腰腹臀部形态的判别模型。结果表明,青年女性腰腹臀部可分为大众型、扁平型、腹凸型、臀凸型4类,分别占样本总数的58.82%、27.86%、8.36%和4.95%。分析获得4类体型对应的裤装样板差异,有效提高了裤装合体性,青年女性腰腹臀部形态判别准确率达96.92%。

并行时空处理模型下的快速N-body算法

图形处理器(graphic processing unit,GPU)的最新发展已经能够以低廉的成本提供高性能的通用计算。基于GPU的CUDA(compute unified device architecture)和OpenCL(open computing language)编程模型为程序员提供了充足的类似于C语言的应用程序接口(application programming interface,API),便于程序员发挥GPU的并行计算能力。采用图形硬件进行加速计算,通过一种新的GPU处理模型——并行时间空间模型,对现有GPU上的N-body实现进行了分析,从而提出了一种新的GPU上快速仿真N-body问题的算法,并在AMD的HD Radeon 5850上进行了实现。实验结果表明,相对于CPU上的实现,获得了400倍左右的加速;相对于已有GPU上的实现,也获得了2至5倍的加速。

地月历表误差对共线平动点周期轨道的误差影响分析

基于圆形限制性三体问题下地月平动点的3阶轨道解析解,分析不同初值条件下的轨道演化特性,并基于误差传播理论研究地月历表误差对地月共线平动点周期轨道在不同初值及初值误差时的影响。结果表明:1)轨道误差与地月历表误差在同一个量级,当地月历表误差均值不为0时,其峰值大约为地月历表误差的2.5倍,轨道误差随时间变化的无量纲周期约为轨道无量纲周期的0.5倍;2)在同一条轨道的不同位置,地月历表误差影响存在较大差异,平面Lyapunov轨道、Halo轨道和垂直Lyapunov轨道误差的峰值点分别位于或接近X向最大值与最小值处、Z向最大值与最小值处和z=0处。

晶状体周围解剖结构与临床的关系

由于晶状体高度透明,且周围结构比较复杂,再加上其特殊的生物力学特性,想要精确地观察到晶状体周围的解剖结构有较大的难度。但近些年随着显微集成术中相干光层析成像术(OCT)的问世,眼科医生得以细致准确地观察晶状体周围结构[1,2],也使得越来越多的人开始探寻晶状体周围结构在临床上的应用。本文将综述以往相关文献,就晶状体周围结构与眼科临床的关系予以阐述。

解构与重构:元宇宙空间中的虚拟身体

“身体转向”与“空间转向”是20世纪西方哲学的两大转向,元宇宙问题的出现,将身体理论与空间理论引入了技术领域。元宇宙场域的复杂性特征,促使虚拟身体、真实身体与元宇宙空间形态及其关系问题具有新意涵。三种形态被置于多维度的交互中,既可能导向抽象空间,重构二元对立的哲学传统,使虚拟身体和真实身体在离身化中分裂,也可能导向差异性空间,模糊空间与身体的界限,使虚拟身体和真实身体在具身化中聚合,生产出全新意涵。观察、阐释元宇宙空间中缠绕着的复杂辩证关系,正是将元宇宙问题上升到形而上学层面的重要途径。

深空探测器多智能体强化学习自主任务规划

针对深空探测器执行附着任务时各子系统协同规划自主性、快速性和自适应性的要求,提出一种基于近端策略优化方法的多智能体强化学习协同规划,将单智能体近端策略优化算法与多智能体混合式协作机制相融合,设计了一种多智能体自主任务规划模型,并引入噪声正则化优势值解决多智能体集中训练中协同策略过拟合的问题。仿真结果表明,多智能体强化学习自主任务规划方法能根据实时环境变化,对智能自主优化小天体附着任务的协作策略适时调整,与改进前的算法相比提高了任务规划成功率和规划解的质量,缩短了任务规划的时间。