Wireless Positioning Algorithm Based on RSS in Limited Space

Yongxing Wang,Gang Hua,Yonggang Xu,Hongsheng Yin 보안공학연구지원센터 2016 International Journal of Signal Processing, Image Vol.9 No.1

Optimization Approach for a Catamaran Hull Using CAESES and STAR-CCM+

Zhang Yongxing,김동준 한국해양공학회 2020 韓國海洋工學會誌 Vol.34 No.4

This paper presents an optimization process for a catamaran hull form. The entire optimization process was managed using the CAD-CFD integration platform CAESES. The resistance of the demi-hull was simulated in calm water using the CFD solver STAR-CCM+, and an inviscid fluid model was used to reduce the computing time. The Free-Form Deformation (FFD) method was used to make local changes in the bulbous bow. For the optimization of the bulbous bow, the Non-dominated Sorting Genetic Algorithm (NSGA)-II was applied, and the optimization variables were the length, breadth, and angle between the bulbous bow and the base line. The Lackenby method was used for global variation of the bow of the hull. Nine hull forms were generated by moving the center of buoyancy while keeping the displacement constant. The optimum bow part was selected by comparing the resistance of the forms. After obtaining the optimum demi-hull, the distance between two demi-hulls was optimized. The results show that the proposed optimization sequence can be used to reduce the resistance of a catamaran in calm water.

Characterization of Hot-Extruded Mg–Gd–Y–Zn–Zr Alloy Containing a Novel Lamellar Structure and Related High Elevated-Temperature Mechanical Properties

Xu Wang,Yongxing Zhao,Yuanchun Huang 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.9

Hot extrusion was introduced to the Mg–10Gd–3Y–1.5Zn–0.5Zr alloy and microstructure evolution, texture configurationand elevated-temperature mechanical properties were investigated. The results show that the LPSO phase network-distributedalong grain boundaries in the as-cast and homogenized alloys is broken and elongated after extrusion, and is streamlined alongthe extrusion direction (ED). After extrusion, a completely recrystallized microstructure with equiaxed grains of ~ 10 μmis formed. The most notable feature in as-extruded alloy is numerous fine lamellar structures in DRXed grains, which wereidentified as basal stacking faults (SFs) with nano-spaced by TEM analysis. The < 0001 > //TD texture results in the hardorientation of most grains along ED. The extruded alloy exhibits excellent elevated-temperature mechanical properties(UTS/287 MPa and YS/218 MPa at 300 °C; UTS > 200 MPa at 350 °C) along ED, which is significantly higher than alloyswith similar composition or even higher rare earth content. The high elevated-temperature strength is mainly related to thefiber strengthening effect of streamline-distributed LPSO, the skeleton support effect of numerous SFs with nano spacing,and the texture strengthening effect of hard grain orientation.

Fracture behaviors of tunnel lining caused by multi-factors: A case study

Zhao, Yiding,Zhang, Yongxing,Yang, Junsheng Techno-Press 2019 Advances in concrete construction Vol.8 No.4

The cracking and spalling caused by fracture of concrete lining have adverse impacts on serviceability and durability of the tunnel, and the subsequent maintenance work for damaged structure needs to be specific to the damaging causes. In this paper, a particular case study of an operational tunnel structure is presented for the serious cracking and spalling behaviours of concrete lining, focusing on the multi-factors inducing lining failure. An integrated field investigation is implemented to characterize the spatial distribution of damages and detailed site situations. According to results of nondestructive inspection, insufficient lining thickness and cavity behind lining are the coupled-inducement of lining failure bahaviors. To further understanding of the lining structure performance influenced by these multiple construction deficiencies, a reliable numerical simulation based on extended finite element method (XFEM) is performed by using the finite element software. The numerical model with 112 m longitudinal calculation, 100 m vertical calculation and 43 m vertical depth, and the concrete lining with 1450 solid elements are set enrichment shape function for the aim of simulating cracking behavior. The numerical simulation responses are essentially in accordance with the actual lining damaging forms, especially including a complete evolutionary process of lining spalling. This work demonstrates that the serious lining damaging behaviors are directly caused by a combination of insufficient thickness lining and cavity around the surrounding rocks. Ultimately, specific maintenance work is design based on the construction deficiencies, and that is confirmed as an efficient, time-saving and safe maintenance method in the operational railway tunnel.

Magnetic Assembly of Nonmagnetic Particles into Photonic Crystal Structures

He, Le,Hu, Yongxing,Kim, Hyoki,Ge, Jianping,Kwon, Sunghoon,Yin, Yadong American Chemical Society 2010 NANO LETTERS Vol.10 No.11

<P>We report the rapid formation of photonic crystal structures by assembly of uniform nonmagnetic colloidal particles in ferrofluids using external magnetic fields. Magnetic manipulation of nonmagnetic particles with size down to a few hundred nanometers, suitable building blocks for producing photonic crystals with band gaps located in the visible regime, has been difficult due to their weak magnetic dipole moment. Increasing the dipole moment of magnetic holes has been limited by the instability of ferrofluids toward aggregation at high concentration or under strong magnetic field. By taking advantage of the superior stability of highly surface-charged magnetite nanocrystal-based ferrofluids, in this paper we have been able to successfully assemble 185 nm nonmagnetic polymer beads into photonic crystal structures, from 1D chains to 3D assemblies as determined by the interplay of magnetic dipole force and packing force. In a strong magnetic field with large field gradient, 3D photonic crystals with high reflectance (83%) in the visible range can be rapidly produced within several minutes, making this general strategy promising for fast creation of large-area photonic crystals using nonmagnetic particles as building blocks.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2010/nalefd.2010.10.issue-11/nl103008v/production/images/medium/nl-2010-03008v_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl103008v'>ACS Electronic Supporting Info</A></P>

Online Hot Topic Detection Based on Segmented Timeline and Aging Theory

Ruiguo Yu,Xiaodong Xie,Yongxing Li,Mankun Zhao,Xuyuan Dong,Muwen He,Peng Chang,Zan Wang 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.2

With a great deal of digitized textual information now available on the internet, it is almost impossible for people to assimilate all the information timely. Therefore, the technologies of topic detection and tracking are used for constructing news topics from news stories in order to bring convenience to people. However, traditional topic detection methods are not always so effective in detecting emerging hot news topics in a short period of time, and most topic detection methods use single-pass clustering algorithm which is with low accuracy and very sensitive to the input sequence of news documents. In order to improve clustering accuracy, we utilize a temporal distance factor to segment timeline into equal parts and propose a novel two-times single-pass clustering algorithm to deal with news stories in each part of timeline separately. Moreover, the aging theory is combined with our approach to build life-span model of topics from which we can obtain variation trend of hotness value of topics. The results of experiments show that our approach is effective and the life circle model of topics established by our method can conform to reality well.

Structural monitoring and analyses on the stability and health of a damaged railway tunnel

Zhao, Yiding,Yang, Junsheng,Zhang, Yongxing,Yi, Zhou Techno-Press 2021 Advances in concrete construction Vol.11 No.5

In this paper, a study of stability and health of a newly-built railway tunnel is presented. The field test was implemented to monitor the secondary lining due to the significant cracking behaviors influenced the stability and health of the tunnel structure. Surface strain gauges were installed for monitoring the status of crack openings, and the monitoring outputs demonstrated that the cracks were still in the developing stage. Additionally, adjacent tunnel and poor condition of surrounding rock were identified as the causes of the lining cracking by systematically characterizing the crack spatial distribution, tunnel site and surrounding rock conditions. Reconstruction of partial lining and reconstruction of the whole secondary lining were designed as the maintenance projects for different cracking regions based on the construction feasibility. For assessing the health conditions of the reinforced lining, embedded strain gauges were set up to continuously measure the strain and the internal force of the reconstructed structures. For the partially reconstructed lining, the outputs show the maximum tensile elongation is 0.018 mm during 227 days, which means the structure has no obvious deformation after maintenance. The one-year monitoring of full-section was implemented in the other two completely reconstructed cross-sections by embedded strain gauge. The outputs show the reconstructed secondary lining has undertaken the pressure of surrounding rock with the time passing. According to the calculated compressive and tensile safety factors, the completely reconstructed lining has been in reliable and safe condition during the past year after reinforcement. It can conclude that the aforementioned maintenance projects can effectively ensure the stability and health of this tunnel.

Preparation and Characterization of Carrageenase Immobilized onto Polyethyleneimine-Modified Pomelo Peel

Yin Qin,Batbatan Christopher G.,Li Yongxing,Zhang Yonghui,Yang Qiuming,Xiao Anfeng 한국미생물·생명공학회 2024 Journal of microbiology and biotechnology Vol.34 No.1

In this study, carrageenase immobilization was evaluated with a concise and efficient strategy. Pomelo peel cellulose (PPC) modified by polyethyleneimine (PEI) using the physical absorption method was used as a carrier to immobilize carrageenase and achieved repeated batch catalysis. In addition, various immobilization and reaction parameters were scrutinized to enhance the immobilization efficiency. Under the optimized conditions, the enzyme activity recovery rate was more than 50% and 4.1 times higher than immobilization with non-modified pomelo peels. The optimum temperature and pH of carrageenase after immobilization by PEI-modified pomelo peel, at 60°C and 7.5 respectively, were in line with the free enzyme. The temperature resistance was reduced, inconsistent with free enzyme, and pH resistance was increased. A significant loss of activity (46.8%) was observed after reusing it thrice under optimal reaction conditions. In terms of stability, the immobilized enzyme conserved 76.0% of the initial enzyme activity after 98 days of storage. Furthermore, a modest decrease in the kinetic constant (Km) value was observed, indicating the improved substrate affinity of the immobilized enzyme. Therefore, modified pomelo peel is a verified and promising enzyme immobilization system for the synthesis of inorganic solvents.

Recovery of zinc and iron from high iron-bearing zinc calcine by selective reduction roasting

Junwei Han,Wei Liu,Wenqing Qin,Bing Peng,Kang Yang,Yongxing Zheng 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.22 No.-

A novel method to recover zinc and iron from high iron-bearing zinc calcine by reduction roasting-lowacid leaching-magnetic separation was proposed. The effects of roasting and leaching conditions wereinvestigated and their optimum conditions were established. Meanwhile, the mineralogical changesduring the processes were characterized by XRD, VSM, SEM and LPSA. The results show the ZnFe2O4 inthe calcine was decomposed into ZnO and Fe3O4, and about 92.6% Zn was extracted from the roastedcalcine with reporting most of iron as magnetite into the residue. Finally, more than 90% Fe wasrecovered from the residue by magnetic separation method.

An Iterative Computing Method for Load Effect of Bidirectional Reinforced Embankment

Weizheng Liu,Kang Sun,Weihua Lu,Junhui Zhang,Yongxing Zhang,Bo Yang 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.5

Bidirectional reinforced embankment (BRE) technology, pile supporting in vertical and geosynthetic reinforcement in horizontal, has been widely adopted in engineering practice to control total and/or differential settlement. In design, the load distribution of BRE is essential for determining pile size (i.e., diameter and length), pile spacing, pile cap details (if any), and properties of geosynthetic reinforcement, et al. Several methods have been proposed in previous studies to investigate the load bearing mechanism in the BRE platform. However, resistance of foundation soil is typically neglected, which implies that the load on piles would be overestimated if the resistance of foundation soil is neglected or over weakened. The reason for this overestimation is that larger geosynthetic deflection would be expected without the reaction of foundation soil, which would cause a more significant soil arching and thus more load would be transferred to piles. To minimize this overestimation, a method for analyzing load transfer mechanism in the BRE was proposed, considering the subsoil resistance as well as the existence of neutral plane (i.e., zero skin friction). An equal settlement was assumed for soils at the embankment bottom and the foundation top. The iteration process was adopted to solve equations to determine the load shared by piles and soils. In derivation, the soil arch height in the embankment was calculated instead of being assumed in existing methods. A flow chart was developed to solve equations of the proposed method and two case histories from literatures were used to compose the rationality verification. Compared with the field measurement and numerical calculation, this study can be more effective in calculating loads shared by piles and soils in the BRE for the working condition with better pile end bearing stratum.