41 research outputs found
Case study on deformation control of upper-soft and lower-hard large span tunnel station using combined control technology and monitoring demonstration
A large number of shallow buried tunnels are built in the city nowadays and the special strata such as large upper-soft and lower-hard ground often encountered. Deformation control of strata is the focus issue related to the construction safety. Based on Dalian metro Hing Street station with the classical geological condition of upper-soft and lower-hard ground, this paper fully used a combined control method including six different support measures to control the deformation of surrounding rock. 3D finite element model was setup to analyze the construction effect of combined control measures and the monitoring in-site was carried out to verify the deformation control effect of combined control method. It shows that the maximum surface subsidence value is gradually reduced with the support measures gradually increasing. In the case of various supports the maximum sedimentation value is 2.67 cm, which is 42. 1% lower than that of not using control method and the control effect is obvious. In addition, it can be seen that the two-layer initial support and additional large arch foot have the best effect on controlling the ground surface settlement with reduction of 11.7% and 20.2%, respectively. The research results can provide practical experience for the construction of such tunnels, and guide the design and construction of the tunnel in the future
High-Performance and Flexible Thermoelectric Films by Screen Printing Solution-Processed Nanoplate Crystals
Screen printing allows for direct conversion of thermoelectric nanocrystals into flexible energy harvesters and coolers. However, obtaining flexible thermoelectric materials with high figure of merit ZT through printing is an exacting challenge due to the difficulties to synthesize high-performance thermoelectric inks and the poor density and electrical conductivity of the printed films. Here, we demonstrate high-performance flexible films and devices by screen printing bismuth telluride based nanocrystal inks synthesized using a microwave-stimulated wet-chemical method. Thermoelectric films of several tens of microns thickness were screen printed onto a flexible polyimide substrate followed by cold compaction and sintering. The n-type films demonstrate a peak ZT of 0.43 along with superior flexibility, which is among the highest reported ZT values in flexible thermoelectric materials. A flexible thermoelectric device fabricated using the printed films produces a high power density of 4.1 mW/cm2 with 60°C temperature difference between the hot side and cold side. The highly scalable and low cost process to fabricate flexible thermoelectric materials and devices demonstrated here opens up many opportunities to transform thermoelectric energy harvesting and cooling applications
Study on the relation between mineral compositions of rock and construction characteristics of tunnel in cold regions: a case
Mineral composition of rock has a very important influence on the physical and mechanical properties of tunnel surrounding rock. Take Dangjianshan tunnel in cold regions for example, the rock specimens in different parts of tunnel were taken to carry out the detection test of mineral composition. By the detail qualitative and quantitative analysis, the relationship between mineral composition and surrounding rock engineering properties was explored. First of all, the composition and content of minerals contained in in the rock specimens were detected by X ray fluorescence spectrometer and X ray powder diffraction. The detection results show that rock of tunnel contains high hardness minerals such as quartz and feldspar which were proven by initial engineering geological investigation report, in addition, it also contains several kinds of low hardness minerals including inclined chlorite and illite which may exhibit large deformation characteristic of soft rock after the tunnel excavation in case of meeting water and weathering conditions. The total content of inclined chlorite and illite accounted for a considerable component in main tunnel, inclined shaft and parallel pilot respectively and the influence on surrounding rock engineering properties cannot be ignored. Therefore, mineral composition detection must be paid attention to after tunnel excavation. Secondly, the effects of mineral composition on surrounding rock were analyzed in aspects of rock strength, weathering resistance, water softening property and excavation deformation through comparing the rock samples in different parts of tunnel. The comparative results showed that when the mineral contents is high with high hardness and poor hydrophilicity, tunnel surrounding rock plays a better performance of physical and mechanical properties, vice versa. Finally, according to the specific geological and construction parameters of the tunnel, the correlation analysis was studied about the vault settlement after tunnel excavation and the hydrophilicity mineral content in main cave. The logarithmic relationship between them was found and the correlation coefficient was 0.98. It can provide a useful reference for the settlement prediction of Dangjinshan tunnel construction
A Path Optimization Algorithm for Multiple Unmanned Tractors in Peach Orchard Management
In order to improve the management efficiency of peach orchards, this paper considers the cooperative operation scheme of multiple unmanned tractors. According to the actual situation, this paper constructs the path planning model of multiple unmanned tractors in a standard peach orchard, designs the objective function to optimize the total turning time and total operating time according to the tractor driving parameters, and solves it by improving the differential evolution algorithm. Aiming at the premature convergence problem, the permutation matrix is introduced to represent the driving paths of multiple unmanned tractors. Then, the dynamic parameters are adopted to make the parameters change with the number of iterations, and the elite selection strategy is used to eliminate the redundant feasible solutions. An Adaptive Elite Differential Evolution (AEDE) algorithm suitable for multi-tractor path optimization is proposed. The results show that, compared with the traditional Differential Evolution algorithm (Differential Evolution, DE), the total turning time and total operating time in the rectangular peach orchard optimized by AEDE are reduced by 3.34% and 0.87%, respectively. Compared with the block operation, the total turning time and total operating time of the AEDE-optimized rectangular peach orchard operation path were reduced by 37.37% and 9.47%, respectively. Experiments show that AEDE, which optimizes the operating path of multi-tractors in standard peach orchards, is able to improve the efficiency and reduce the operating time
Beam-Based Alignment for the Rebaselining of CLIC RTML
The first stage of the CLIC is proposed to be at 380 GeV. So the Ring To Main Linac (RTML), which transport the beams from the damping ring to main linac with minimal emittance growth, should be restudied due to the new beam properties. In this paper the two bunch compressors in the RTML are redesigned. Then a complete study of the static beam-based alignment techniques along RTML is presented. The beam-based correction includes one-to-one and dispersion-free steering, then a global correction using tuning bumps is applied to reduce the final emittance and mitigate the effects of coupling. The results showed that the emittance growth budgets can be met both in the horizontal and vertical planes
First Start-to-End BBA Results in the CLIC RTML
CLIC is a design study for a 3 TeV linear collider designed for the high-energy frontier in the post-LHC era. The Ring To Main Linac (RTML) part of CLIC is a long section that must transport the electron and the positron bunches through more than 20 km of beamlines, with minimal emittance growth. A sequence of three beam-based alignment (BBA) techniques must be used to transport the beam: one-to-one correction (OTO), dispersion-free steering (DFS), and sextupole correction (SCS). The performance of the whole correction procedure is tested under several realistic imperfections: magnets position offsets, magnets rotation errors, magnets strength errors and emittance measurement errors. The results show that the emittance growth budgets can be met both in the horizontal and vertical planes
BBA and Coupling Correction at CLIC RTML
The CLIC Ring To Main Linac (RTML) must transport the electron and the positron bunches through more than 20 km of beamlines with minimal emittance growth. The turnaround loops (TAL) are one of the most critical sections, featuring a lattice designed to minimize emittance growth due to synchrotron radiation emission and chromaticity, while being isochronous to avoid bunch lengthening. With such a design, the impact of static imperfections like element misalignment is particularly critical. In this paper a study of the Beam-Based Alignment (BBA) techniques in the TAL of the CLIC RTML is presented. In order to reduce the emittance growth, the one-to-one and dispersion-free corrections have been tested. The results showed that the emittance growth budgets can be met both in the horizontal and vertical planes. The impact of coupling errors due to magnets rolls on the emittance has also been studied and a coupling correction section has been designed and inserted in the lattice
A Chinese Face Dataset with Dynamic Expressions and Diverse Ages Synthesized by Deep Learning
Abstract Facial stimuli have gained increasing popularity in research. However, the existing Chinese facial datasets primarily consist of static facial expressions and lack variations in terms of facial aging. Additionally, these datasets are limited to stimuli from a small number of individuals, in that it is difficult and time-consuming to recruit a diverse range of volunteers across different age groups to capture their facial expressions. In this paper, a deep-learning based face editing approach, StyleGAN, is used to synthesize a Chinese face dataset, namely SZU-EmoDage, where faces with different expressions and ages are synthesized. Leverage on the interpolations of latent vectors, continuously dynamic expressions with different intensities, are also available. Participants assessed emotional categories and dimensions (valence, arousal and dominance) of the synthesized faces. The results show that the face database has good reliability and validity, and can be used in relevant psychological experiments. The availability of SZU-EmoDage opens up avenues for further research in psychology and related fields, allowing for a deeper understanding of facial perception
Update of the CLIC Positron Source
The baseline positron source of CLIC has been optimised for the 3 TeV c.o.m. energy. Now the first stage of the CLIC is proposed to be at 380 GeV. Recently, the positron transmission efficiency from the tungsten target to the damping rings injection has been improved by 2.5 times. This opened the possibility for an optimisation of the whole positron source, comprising the injector linacs, aimed at improving its performance and its overall power efficiency. In this paper the key parameters of the positron source, which include the current and the energy of the primary electron beam, the thickness of the crystal and amorphous tungsten targets, the distance between the two targets, the adiabatic matching device (AMD) and pre-injector linacs, are optimized to improve the overall power efficiency