Analysis of Geotechnical Engineering Safety Technology in Urban Underground Space Construction

With the accelerating pace of urbanization, the development and application of urban underground space has attracted much attention. In the construction of urban underground space, geotechnical engineering safety is the key point for construction. Based on this, this paper analyzes the application of geotechnical engineering safety technology in urban underground space construction, in hope that this analysis can provide a scientific reference for the rational application of geotechnical engineering safety technology as well as the construction and development of urban underground space.

An Analysis of the Construction of the Multiple Spaces in The Scarlet Letter

Nathaniel Hawthorne, one of the classic writers of American romanticism, wrote many classic works throughout his life, including The Scarlet Letter, the representative of romantic novels and his outstanding masterpiece. Extensive attention has paid on it since it was published. Many literary critics use different theories to explain this work, many of which explore the theme including good and evil, love and hate, and culture under the influence of Puritanism. However, previous researches have paid less attention on the space feature of The Scarlet Letter, and in the traditional narratological research, the space factor has also been ignored for a long time. In this thesis, the author will take space as the starting point based on the relevant spatial theory and spatial narrative research results, and interpret the multiple space construction in The Scarlet Letter in detail, further analyzing the narrative strategy adopted by Hawthorne in order to explore the cultural connotation of the multiple spaces constructed in his works.

Generalized Lieb-Schultz-Mattis theorem on bosonic symmetry protected topological phases

We propose and prove a family of generalized Lieb-Schultz-Mattis~(LSM) theorems for symmetry protected topological~(SPT) phases on boson/spin models in any dimensions. The ``conventional'' LSM theorem, applicable to e.g. any translation invariant system with an odd number of spin-1/2 particles per unit cell, forbids a symmetric short-range-entangled ground state in such a system. Here we focus on systems with no LSM anomaly, where global/crystalline symmetries and fractional spins within the unit cell ensure that any symmetric SRE ground state must be a non-trivial SPT phase with anomalous boundary excitations. Depending on models, they can be either strong or ``higher-order'' crystalline SPT phases, characterized by non-trivial surface/hinge/corner states. Furthermore, given the symmetry group and the spatial assignment of fractional spins, we are able to determine all possible SPT phases for a symmetric ground state, using the real space construction for SPT phases based on the spectral sequence of cohomology theory. We provide examples in one, two and three spatial dimensions, and discuss possible physical realization of these SPT phases based on condensation of topological excitations in fractionalized phases.

State-space Construction of Hybrid Petri Nets with Multiple Stochastic Firings

Hybrid Petri nets have been extended to include general transitions that fire after a randomly distributed amount of time. With a single general one-shot transition the state space and evolution over time can be represented either as a Parametric Location Tree or as a Stochastic Time Diagram . Recent work has shown that both representations can be combined and then allow multiple stochastic firings. This work presents an algorithm for building the Parametric Location Tree with multiple general transition firings and shows how its transient probability distribution can be computed using multi-dimensional integration. We discuss the (dis-)advantages of an interval arithmetic and a geometric approach to compute the areas of integration. Furthermore, we provide details on how to perform a Monte Carlo integration either directly on these intervals or convex polytopes, or after transformation to standard simplices. A case study on a battery-backup system shows the feasibility of the approach and discusses the performance of the different integration approaches.

The Mass Driver Project: A Preliminary Design of a Material Transfer System for Space Construction Projects Using Open Source Design Principles

This project attempts to adapt open source software development principles to the evaluation and design of a mass driver system capable of transporting construction material from the Earth's surface to orbit as a stream of inline, discrete material packages following one after another. The design process does not identify any "show stopper" physical effects. The final design of the system proposes using a novel launch rail concept to send a stream of 10 kg. material packages to a 10 000 km apogee altitude, where a rocket motor fires to place the material package into a highly elliptical orbit. A satellite, in a similar orbit, collects the material packages and distributes than to a space construction project. Further work is required to evaluate the aerodynamic issues related to the material package stream. Open source collaboration on the design did not occur; however seven potential collaborators were identified.

The Mass Driver Project: A Preliminary Design of a Material Transfer System for Space Construction Projects Using Open Source Design Principles

This project attempts to adapt open source software development principles to the evaluation and design of a mass driver system capable of transporting construction material from the Earth's surface to orbit as a stream of inline, discrete material packages following one after another. The design process does not identify any "show stopper" physical effects. The final design of the system proposes using a novel launch rail concept to send a stream of 10 kg. material packages to a 10 000 km apogee altitude, where a rocket motor fires to place the material package into a highly elliptical orbit. A satellite, in a similar orbit, collects the material packages and distributes than to a space construction project. Further work is required to evaluate the aerodynamic issues related to the material package stream. Open source collaboration on the design did not occur; however seven potential collaborators were identified.

Underground space optimization of smart city based on information processing technology

This study explores the underground space optimization method of smart city based on information processing technology to save space optimization operation time. Taking coordinate of intersection point, radius of intersection point, mileage of vertical slope change point and elevation of slope change point as design variables, taking total cost of underground space construction of smart city as objective function and taking plane, vertical section, horizontal and vertical combination and environmental impact as constraint conditions, a multi-objective optimization mathematical model of underground space of smart city was constructed. Parete genetic algorithm in information processing technology was used to solve the multi-objective optimization mathematical model of the underground space of smart city, realize the automatic search for the optimal scheme of the underground space of smart city, and complete the intelligent optimization process of the underground space construction scheme of smart city. The results show that the method obtained from this study can effectively optimize the underground space of smart city and obtain the optimal subway laying line, save space and optimize operation time and improve the convergence of the method.

Haynes 242 Alloy for Lares 2 Satellite

The satellite LARES 2 is designed to test dragging of inertial frames, or frame-dragging, predicted by Einstein’s theory of General Relativity, with accuracy of a few parts in a thousand. For this purpose, besides the typical requirements for a space construction, a high density alloy must be used. In this paper are reported the studies performed on a nickel alloy, the Haynes 242, that is considered a possible candidate for manufacturing all the metallic parts of LARES 2 and other passive geodetic satellites. Haynes 242 density and mechanical properties are compliant with the requirements of the mission. Three different casting with the nominal composition of the alloy have been prepared and tested along with a commercial bar of Haynes 242. The results of tensile and hardness tests on several specimens with different aging time are reported, along with the relevant metallographic analysis. Furthermore, a test on the machinability, performed on a screw, which is the most demanding item from the manufacturing point of view, is reported.