Optic-fiber gravity frequency transfer network

2021 ◽  
Author(s):  
Anh The Hoang ◽  
WenBin Shen
Keyword(s):  
Optical Fibers ◽  
Rapid Development ◽  
Space Station ◽  
Orthometric Height ◽  
Relativity Theory ◽  
Gravity Potential ◽  
General Relativity Theory ◽  
Long Time ◽  
High System ◽  
Frequency Transfer

<p>According to<strong> </strong>Einstein’s general relativity theory (GRT), a clock at a position with higher potential runs faster than a clock at a position with lower potential. Hence, inversely, one can determine the gravity potential (geopotential) and orthometric height based on precise clocks. If a clock with an accuracy of 10<sup>-18</sup> is used, the geopotential difference between two points can be determined with an accuracy of centimeters level.<strong> </strong>With the rapid development of science and technology, optical clocks achieve 10<sup>-18</sup> stability, which opens up opportunity for scientists to practically determine geopotential as well as orthometric height using optical clocks. One of the challenges of classical geodesic in the long time has been the unification of local hight systems. To complete this task is very difficult because each country has a regional high system. This problem can be solved if using a clock network, which overcomes the weaknesses of the spirit leveling method. Here we provide a formulation to establish a model of a network using optical clocks linked together by optical fibers for the purpose of determining the geopotential and establishing a unified world hight system at centimeter accuracy level. This study is supported by National Natural Science Foundation of China (NSFC) (grant Nos. 41721003, 42030105, 41631072, 41874023, 41804012), and Space Station Project (2020)228.</p><p><strong>Key words:</strong><strong> </strong>GRT, optical clocks network, frequency transfer, geopotential, orthometric height</p>

scholarly journals BIANCHI I SOLUTIONS OF EFFECTIVE QUADRATIC GRAVITY

2012 ◽  
Vol 21 (04) ◽  
pp. 1250037 ◽  
Author(s):  
DANIEL MÜLLER ◽  
JULIANO A. DE DEUS
Keyword(s):  
Numerical Solutions ◽  
Relativity Theory ◽  
De Sitter ◽  
General Relativity Theory ◽  
Spatial Metrics ◽  
Effective Gravity ◽  
Bianchi I ◽  
Quadratic Theory ◽  
Quadratic Gravity ◽  
Planck Time

It is believed that soon after the Planck time, Einstein's general relativity theory should be corrected to an effective quadratic theory. Numerical solutions for the anisotropic generalization of the Friedmann "flat" model E3 for this effective gravity are given. It must be emphasized that although numeric, these solutions are exact in the sense that they depend only on the precision of the machine. The solutions are identified asymptotically in a certain sense. It is found solutions which asymptote de Sitter space, Minkowski space and a singularity. This work is a generalization for nondiagonal spatial metrics of a previous result obtained by one of us and a collaborator for Bianchi I spaces.

scholarly journals Vaidya solutions in general covariant Hořava–Lifshitz gravity without projectability: Infrared limit

2014 ◽  
Vol 23 (08) ◽  
pp. 1450068 ◽  
Author(s):  
O. Goldoni ◽  
M. F. A. da Silva ◽  
G. Pinheiro ◽  
R. Chan
Keyword(s):  
General Relativity ◽  
Gauge Field ◽  
Radiation Field ◽  
Relativity Theory ◽  
Covariant Theory ◽  
Spherically Symmetric ◽  
Theory U ◽  
General Relativity Theory ◽  
Infrared Limit ◽  
Symmetric Spacetime

In this paper, we have studied nonstationary radiative spherically symmetric spacetime, in general covariant theory (U(1) extension) of Hořava–Lifshitz (HL) gravity without the projectability condition and in the infrared (IR) limit. The Newtonian prepotential φ was assumed null. We have shown that there is not the analogue of the Vaidya's solution in the Hořava–Lifshitz Theory (HLT), as we know in the General Relativity Theory (GRT). Therefore, we conclude that the gauge field A should interact with the null radiation field of the Vaidya's spacetime in the HLT.

scholarly journals Development of COVID-19 vaccines utilizing gene therapy technology

2021 ◽  
Author(s):  
Hironori Nakagami
Keyword(s):  
Viral Vectors ◽  
High Efficiency ◽  
Genetic Disorders ◽  
Rapid Development ◽  
Adenovirus Vector ◽  
Phase 3 ◽  
Double Blind ◽  
Time Period ◽  
Short Period ◽  
Long Time

Abstract There is currently an outbreak of respiratory disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Coronavirus disease 2019 (COVID-19) is caused by infection with SARS-CoV-2. Individuals with COVID-19 have symptoms that are usually asymptomatic or mild in most initial cases. However, in some cases, moderate and severe symptoms have been observed with pneumonia. Many companies are developing COVID-19 vaccine candidates using different technologies that are classified into four groups (intact target viruses, proteins, viral vectors and nucleic acids). For rapid development, RNA vaccines and adenovirus vector vaccines have been urgently approved, and their injection has already started across the world. These types of vaccine technologies have been developed over more than 20 years using translational research for use against cancer or diseases caused by genetic disorders but the COVID-19 vaccines are the first licensed drugs to prevent infectious diseases using RNA vaccine technology. Although these vaccines are highly effective in preventing COVID-19 for a short period, safety and efficiency evaluations should be continuously monitored over a long time period. As the time of writing, more than 10 projects are now in phase 3 to evaluate the prevention of infection in double-blind studies. Hopefully, several projects may be approved to ensure high-efficiency and safe vaccines.

Propagators and commutators in general relativity

1962 ◽  
Vol 270 (1342) ◽  
pp. 342-345 ◽  
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
General Relativity ◽  
Relativity Theory ◽  
Quantum Field ◽  
General Relativity Theory ◽  
Free Fields

In this contribution, my purpose is to study a new mathematical instrument introduced by me in 1958-9: the tensor and spinor propagators. These propagators are extensions of the scalar propagator of Jordan-Pauli which plays an important part in quantum-field theory. It is possible to construct, with these propagators, commutators and anticommutators for the various free fields, in the framework of general relativity theory (see Lichnerowicz 1959 a, b, c , 1960, 1961 a, b, c ; and for an independent introduction of propagators DeWitt & Brehme 1960).

scholarly journals Modeling and Simulation of Sky Survey

2021 ◽  
Vol 11 (16) ◽  
pp. 7584
Author(s):  
Kun Hu ◽  
Hongfei Wang ◽  
Wenzhao Zhang ◽  
Yuohua Xu ◽  
Shengmao He
Keyword(s):  
Modeling And Simulation ◽  
Scheduling Algorithm ◽  
Space Station ◽  
Scientific Output ◽  
Mission Planning ◽  
Design Algorithm ◽  
Sky Survey ◽  
Long Time ◽  
Time Periods ◽  
Design Ideas

Sky surveys with wide and deep field are the key direction of international astronomy research for the next decades. It is worthwhile to study how to design a sky survey algorithm to obtain the maximum scientific output in a limited period of observation. In this paper, the modeling and simulation of a wide and deep sky survey mission are presented using a Staged Design Algorithm (SDA), which takes into account the inefficient time periods and difficult-to-observe sky areas. In order to ensure the effective completion of the long-time survey observation tasks in large sky areas, a two-stage scheduling algorithm is designed. Firstly, the inefficient time periods and difficult observation areas are scheduled, and then the overall observation is carried out. The prearranged schedule is arranged when inefficient time periods or difficult areas are encountered during the overall arrangement. The simulation results are verified on the basic data of the China Space Station Telescope (CSST), and the obtained simulation result is three years ahead of the target of the telescope design to complete the wide and deep sky survey of 15,000 deg2. The design ideas in this paper not only have good results for sky survey observation but also can be extended to similar satellite Earth observation mission planning.

scholarly journals Advanced Thermally Drawn Multimaterial Fibers: Structure-Enabled Functionalities

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Zhe Wang ◽  
Mengxiao Chen ◽  
Yu Zheng ◽  
Jing Zhang ◽  
Zhixun Wang ◽  
...  
Keyword(s):  
Optical Fibers ◽  
Early Stage ◽  
Rapid Development ◽  
Wearable Devices ◽  
Surface Structures ◽  
The Past ◽  
High Scalability ◽  
Drawing Technique ◽  
Symmetric Structures ◽  
Thermal Drawing

Thermally drawn multimaterial fibers have experienced rapid development in the past two decades owing to the high scalability, uniformity, and material and structure compatibility of the thermal drawing technique. This article reviews various multimaterial fibers based on different functional structures and their applications in disparate fields. We start from the functional structures achieved in optical fibers developed in the early stage of thermally drawn fibers. Subsequently, we introduce both typical functional structures and unique structures created in multimaterial fibers for varying applications. Next, we present the early attempts in breaking the axial symmetric structures of thermally drawn fibers for extended functionalities. Additionally, we summarize the current progress on creating surface structures on thermally drawn fibers. Finally, we provide an outlook for this trending topic towards wearable devices and smart textiles.

scholarly journals A study on the use of disposable products in hotels based on low carbon consumption

2021 ◽  
Vol 275 ◽  
pp. 02015
Author(s):  
Kejiang Chen ◽  
Tairan Huang ◽  
Yichen Zhang ◽  
Zimu Zhu
Keyword(s):  
Rapid Development ◽  
Hotel Industry ◽  
Scientific Concept ◽  
Low Carbon ◽  
Carbon Consumption ◽  
Low Carbon Economy ◽  
Sustainable Resources ◽  
Long Time ◽  
Great Pressure ◽  
Carbon Economy

In recent years, the world has been committed to the development of environmental industries and sustainable resources, and continues to implement the strategic idea of the scientific concept of development to prevent environmental pollution and resource waste. However, the nation seems to be accustomed to the use of disposable items such as toothbrushes, toothpaste and slippers in hotels. With the rapid development of the hotel industry, a large number of disposable items have been used in the hotel industry for a long time, which has brought great pressure to the environment and does not meet the requirements of the concept of low-carbon economy and green development. Through the investigation and analysis of the use of disposable products in hotels, this paper explores the solution and feasibility of banning disposable products in hotels, aiming to contribute to the low carbon economy and low carbon consumption.

scholarly journals Analysis and Improvement Strategies of the Phenomenon that What Biology Teachers Teach is not What They Learned in Rural Middle Schools

2020 ◽  
Author(s):  
Richmond Sam Quarm ◽  
Richmond Sam-Quarm ◽  
Mohamed Osman Elamin Busharads ◽  
Juan Peng ◽  
Xuezhong Sun ◽  
...  
Keyword(s):  
Middle School ◽  
Middle Schools ◽  
School Leaders ◽  
Rapid Development ◽  
School Education ◽  
Middle School Education ◽  
Biology Teachers ◽  
Long Time ◽  
Rural Middle School ◽  
The Government

Rural education is a short board of China’s education. It is of great significance to strengthen the construction of the teacher team in rural middle schools for Rural Revitalization in the new era. The problem of structural shortage of teachers, reflected by the phenomenon of “what biology teachers teach is not what they learned” in rural middle schools, is a key issue that has been existing for a long time in the development of rural middle school education in our country. It is also a key problem that must be paid attention to and urgently solved in the face of the new situation, new tasks and new requirements. In response to this phenomenon that caused by the decline of students and the loss of biological teachers in rural middle schools, the government needs to play a supporting role and the school leaders of rural middle schools should innovate their systems and concepts. What’s more, biological teachers should reflect on their hearts and have the educational feelings of being willing to develop the countryside. Only when the government, middle school leaders and biology teachers have formed an educational synergy, can we better solve that harmful phenomenon and promote the healthy and rapid development of rural middle school education.

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