Physical Space Is Finite

Metrological analysis shows that any clock in inertial motion in infinite space shall not have time dilation, due to relativity of such motion in such space. On the other hand, atomic clock in inertial motion in finite space shall exhibit time dilation, due to alteration of momentum of clock-defining particle caused by nonzero curvature of trajectory of such motion in such space. Therefore, time dilation experiment of atomic clock in inertial motion in physical space provides a direct and decisive way of determining geometry of physical space in real-time. Phenomenon of time dilation of atomic clock in inertial motion in physical space has long been observed and confirmed experimentally. Therefore, extent of physical space has to be finite, consistent with result of high precision experiment of free particle in high-speed motion conducted a decade ago.Keywords Geometry of Physical Space, Time Dilation, Atomic Clock, Special Relativity Theory.

Physical Space Was Not Expanding

Plurality of characteristic peaks observed in number density distribution of galaxy redshift reveals that extent of physical space has been finite. Significant portion of observed celestial objects is found pair-wise associated, i.e., the observed lights were emitted from one and same luminescent source but seen at different sky directions of observer, which is a unique phenomenon that can occur but only in finite space. Cosmic microwave radiation has always been interpreted as afterglow of Big Bang event. However, such radiation is shown unobservable to current observer if Hubble-Lemaître Correlation is interpreted as caused by receding motion of celestial objects. On the other hand, cosmic radiation can be understood as a common and ordinary phenomenon due to space lens, a unique property only of finite space. From Sloan Digital Sky Survey data, internal diameter of physical space is measured as 2.0 billion light years. If celestial objects were receding, hence physical space was expanding, then characteristic peaks of finite physical space should not appear evenly in number density distribution of redshift of the objects but more sparsely with respect to redshift increase. However, as revealed by the data, locations of the characteristic peaks in the distributions are rather even that do not match the locations as required by receding motion of object. Therefore, as evidenced by the data, physical space was not expanding, at least during the recent 18 billion years. In addition, considerable portion of observed quasars is found sharing a common factor of ~1/2 for their respective gravitation redshifts.

Study and application of an improved four-dimensional variational assimilation system based on the physical-space statistical analysis for the South China Sea

The four-dimensional variational assimilation(4D-Var)has been widely used in meteorological and oceanographic data assimilation.This method is usually implemented in the model space,known as primal approach(P4D-Var).Alternatively,physical space analysis system(4D-PSAS)is proposed to reduce the computation cost,in which the 4D-Var problem is solved in physical space(i.e.,observation space).In this study,the conjugate gradient(CG)algorithm,implemented in the 4D-PSAS system is evaluated and it is found that the non-monotonic change of the gradient norm of 4D-PSAS cost function causes artificial oscillations of cost function in the iteration process.The reason of non-monotonic variation of gradient norm in 4D-PSAS is then analyzed.In order to overcome the non-monotonic variation of gradient norm,a new algorithm,Minimum Residual(MINRES)algorithm,is implemented in the process of assimilation iteration in this study.Our experimental results show that the improved 4D-PSAS with the MINRES algorithm guarantees the monotonic reduction of gradient norm of cost function,greatly improves the convergence properties of 4D-PSAS as well,and significantly restrains the numerical noises associated with the traditional 4D-PSAS system.

Take Tradition as Bronze Mirror——Some Points of Physical Space in our Modern Cities contrary to the Traditionally Spatial Concept and Means

Take bronze mirror, one can be properly dressed. Take tradition asbronze mirror, we can know some problems of urban planning and designin modern cities. This article is intended to relatively analyse theinadequate space in modern cities on the basis of the traditional ideas andmeans recaardincf space in 9 aspects in order to seek the ways of reform.

Definition and expression of non-symmetric physical properties in space for uniaxial crystals

The anisotropic physical property is the most noteworthy feature of crystals.In this paper,the subscript change method is used to analyze the sign changes of different tensors describing physical properties in uniaxial crystals.The distribution of some physical properties in special point groups exhibits non-symmetry in eight quadrants,which should attract the attention of crystal research.The difference between the crystallographic and physical coordinate systems and the lack of crystal symmetry operations are considered to be the origins of the non-symmetry.To avoid ambiguities and difficulties in characterizing and applying crystal physical properties,eight quadrants in space should be clarified.Hence,we proposed the use of piezoelectric properties to define the positive direction of the optical coordinate axis prior to the research and applications of optical properties.

Investigating the Effect of Sidewalk Flooring on the Behavioral Pattern (Walking) of Citizens in Urban Spaces (Case Study: Vali asr St., Tehran)

The present study has evaluated the effect of architectural forms on the walking activity of citizens as a behavioral model in urban physical spaces.The research hypothesis claims that by designing purposeful and appropriate architectural forms,the behavior and actions of users in urban physical spaces can be to some extent,it designed or controlled,and that the pattern and domains of human behavior in urban streets are the result of the components of environmental quality that are included in the design of that street.The present theoretical proposition has been tested in two sequences from Valiasr Street in Tehran.At the theoretical level,the research method is descriptive-analytical and at the experimental level,it is a survey that has been done using the behavioral research method.The results show that the floor form and street form are the most influential architectural forms in urban physical spaces on the activity of users walking from space in the study sample.Also,some environmental factors have a direct effect on human reactions;The research findings show that people’s speed is directly related to the dimensions of sidewalk carpets and a person tries to take a step according to the senses he receives from the sidewalk flooring form and as a result his speed changes according to those forms.

A Study of Survival Predicaments in Graham Swift’s Waterland from the Perspective of Spatial Theory

In Waterland,contemporary British writer Graham Swift tells the protagonist Tom,using a mix of reality and history recreates the ecological devastation of the Fens Marsh,the fall of the Atkinson family and the spiritual collapse of the people.This paper attempts to explore the dilemma of human existence by starting from Henry’s spatial theory and dividing it into physical space,social space and mental space.

Digital Twin-Driven Intelligent Construction:Features and Trends

Digital twin(DT)can achieve real-time information fusion and interactive feedback between virtual space and physical space.This technology involves a digital model,real-time information management,comprehensive intelligent perception networks,etc.,and it can drive the rapid conceptual development of intelligent construction(IC)such as smart factories,smart cities,and smart medical care.Nevertheless,the actual use of DT in IC is partially pending,with numerous scientific factors still not clarified.An overall survey on pending issues and unsolved scientific factors is needed for the development of DT-driven IC.To this end,this study aims to provide a comprehensive review of the state of the art and state of the use of DT-driven IC.The use of DT in planning,design,manufacturing,operation,and maintenance management of IC is demonstrated and analyzed,following which the driving functions of DT in IC are detailed from four aspects:information perception and analysis,data mining and modeling,state assessment and prediction,intelligent optimization and decision-making.Furthermore,the future direction of research,using DT in IC,is presented with some comments and suggestions.This work will help researchers gain in-depth and systematic understanding of the use of DT,and help practitioners to better promote its implementation in IC.

Achieving highly uniform two-dimensional PbI2 flakes for photodetectors via space confined physical vapor deposition

Two-dimensional(2D) PbI_2 flakes have been attracting intensive attention as one potential candidate for the modern optoelectronics. However, suffered from the instability of kinetics-driven growth, the fabricated 2D PbI_2 flakes have a wide dimensional distribution even under the same conditions. Herein, a novel facile space confined physical vapor deposition(PVD) process is provided to synthesize uniform triangle PbI_2 flakes with high quality. The confined space provides a relatively stable growth environment that renders more control on the growth kinetics, leading to highly uniform triangle PbI_2 flakes with the average size of 5 mm and thickness of 17 nm. Moreover, as-fabricated PbI_2-based photodetectors show promising stable and flexible optoelectronic performances to 470 nm light, including high responsivity(0.72 AW^(-1)), large on/off ratio up to 900, fast photoresponse speed(rise time of 13.5 ms and decay time of 20 ms) and high detectivity(1.04×10^(10) Jones). The well-controllable growth of the uniform triangle PbI_2 flakes and the detailed exploration of their optoelectronic properties are particularly valuable for their further practical applications.

Stability and local bifurcation of parameter-excited vibration of pipes conveying pulsating fluid under thermal loading

The parametric excited vibration of a pipe under thermal loading may occur because the fluid is often transported heatedly. The effects of thermal loading on the pipe stability and local bifurcations have rarely been studied. The stability and the local bifurcations of the lateral parametric resonance of the pipe induced by the pulsating fluid velocity and the thermal loading are studied. A mathematical model for a simply supported pipe is developed according to the Hamilton principle. Two partial differential equations describing the lateral and longitudinal vibration are obtained. The singularity theory is utilized to analyze the stability and the bifurcation of the system solutions. The transition sets and the bifurcation diagrams are obtained both in the unfolding parameter space and the physical parameter space, which can reveal the relationship between the thermal field parameter and the dynamic behaviors of the pipe. The frequency response and the relationship between the critical thermal rate and the pulsating fluid velocity are obtained. The numerical results demonstrate the accuracy of the single-mode expansion of the solution and the stability and local bifurcation analyses. It also confirms the existence of the chaos. The presented work can provide valuable information for the design of the pipeline and the controllers to prevent the structural instability.

Numerical Analysis of Artificial Electron Heating Effects on Polar Mesospheric Winter Echoes

In this paper,an analytical model is used to analyze the modulated polar mesospheric winter echoes(PMWE).The winter parameters were introduced to simulate the effects of different parameters during the artificial electron heating of PMWE.The important role of the charged dust particle in the creation of PMWE is confirmed again.It is found that during the heating of PMWE,the increases of the dust size,dust charge,electron temperature,initial electron density,and ion-neutral collision frequency cause the increase of the electron density irregularity,and hence the PMWE strength.However,with increasing the dust density,the electron density irregularity and the PMWE strength decrease.

Research Advances of the Chinese Meridian Project in 2020-2021

The Chinese Meridian Project(CMP)is a major national science and technology infrastructure invested and constructed by the Chinese government.The project builds space environment observation stations,focusing on the monitoring of the space environment over China,so as to provide a monitoring basis for clarifying the regional characteristics of the space environment over China and its relationship with global change,and making important innovative scientific achievements.The first phase of the CMP passed the national acceptance in 2012.It has been running for nearly ten years and has accumulated more than 8 TB monitoring data.These data are all available to all data users through the data center of the project.From 2020 to 2021,users of CMP data have completed a series of original works,which have solved current scientific problems in the field of space physics research.On the other hand,they also make us look forward to the completion of the second phase of CMP and its application benefits in national major strategic needs and cutting-edge scientific research.

Recent Progress of Microgravity Science Research in China

Microgravity science is an important branch of space science.Its major objective is to study the laws of materials movement in microgravity,as well as to reveal the influence of gravity on the movement of materials in different gravity environments.Application researches relevant to these basic studies are also important contents of microgravity science.The advanced subjects,to some extent,reflect the ability of human beings to understand nature and the R&D level in this field in various countries.In this paper,the recent progress and the latest achievements of microgravity science and application researches in China aboard space platforms such as the Core Capsule Tianhe of the China Space Station(CSS)and satellites,as well as utilizing ground-based short-term microgravity facilities such as the Drop Tower Beijing and TUFF,are summarized,which cover the following sub-disciplines:microgravity fluid physics,microgravity combustion science,space materials science,space fundamental physics,space bio-technology,and relevant space technology applications.

Micro-Newton scale variable thrust control technique and its noise problem for drag-free satellite platforms:a review

High-precision detection in fundamental space physics,such as space gravitational wave detection,high-precision earth gravity field measurement,and reference frame drag effect measurement,is the key to achieving important breakthroughs in the scientific study of fundamental space physics.Acquiring high-precision measurements requires high-performance satellite platforms to achieve“drag-free control”in a near“pure gravity”flight environment.The critical technology for drag-free control is variable thrust control at the micro-Newton scale.Thrust noise is the most important technical indicator for achieving drag-free flight.However,there is no literature about the current status and future prospects of variable thrust control based on thrust noise.Therefore,the micro-Newton variable thrust control technology and the thrust noise of the drag-free satellite platform are reviewed in this work.Firstly,the research status of micro-Newton scale variable thrust control technology and its applications to drag-free satellite platforms are introduced.Then,the noise problem is analyzed in detail and its solution is theoretically investigated in three aspects:“cross-basin flow problem,”“control problem,”and“system instability and multiple-coupled problem.”Finally,a systematic overview is presented and the corresponding suggested directions of research are discussed.This work provides detailed understanding and support for realizing low-noise variable thrust control in the next generation of drag-free satellites.

Big plants--do they limit species coexistence?

Aims According to conventional theory,larger plant species are likely to inflict more intense competition on other(smaller)species.We tested a deducible prediction from this:that a larger species should generally be expected to impose greater limits on the number of species that can coexist with it.Methods Species richness was sampled under plant canopies for a selection of woody species(‘host’species)that display a wide range of adult sizes(from small shrubs to large trees),growing within natural vegetation of the Interior Douglas-fir zone of southern British Columbia,Canada.These data were compared with species richness levels sampled within randomly placed plots within the host species habitat.Important Findings A prominent host species size effect on species richness was detected but only narrowly at the small end of the species size range.Across most(90%)of the increasing size range of host species,the number of species residing under the host canopy showed no significant decrease relative to the number expected by random assembly,based on species richness within randomly defined equivalent areas within the habitat of the host species.This apparent‘null effect’,we suggest,is explained not because these larger species have no effect on community assembly.We postulate that larger species are indeed likely to be more effective in causing competitive exclusion of some smaller species(as expected from conventional theory),but that any potential limitation effect of this on resident species richness is offset for two reasons:(i)larger species also generate niche spaces that they cannot exploit under their own canopies and so have minimal impact(as competitors)on smaller species that can occupy these niches and(ii)certain other small species—despite small size—have effective competitive abilities under the severe competition that occurs within host neighbourhoods of larger species.These and other recent studies call for re-evaluation of traditional views on the role of plant size in affecting competitive ability and community assembly.

Notes and correspondence on ensemble-based three-dimensional variational filters

Several ensemble-based three-dimensional variational (3D-Var) filters are compared. These schemes replace the static background error covariance of the traditional 3D-Var with the ensemble forecast error covariance, but generate analysis ensemble anomalies (perturbations) in different ways. However, it is demonstrated in this paper that they are all theoretically equivalent to the ensemble transformation Kalman filter (ETKF). Furthermore, a new method named EnPSAS is presented. The analysis shows that EnPSAS has a small condition number and can apply covariance localization more easily than other ensemble-based 3D-Var methods.