Structure and morphological characteristics of polygonal salt crust, the West Juyan Lake, China

Guoming Zhang,Yuting Xiao,Mingzhu Xiang,Chang Hong,Bo-Tao Zhang,Lianyou Liu,Peijun Shi,Jifu Liu 한국지질과학협의회 2022 Geosciences Journal Vol.26 No.3

Polygonal salt crust patches (PSCPs) in modern playas have critical hydrologic implications for arid areas, but the morphology and origin of these polygonal features are under debate. This study investigated the structure and morphological characteristics of crustal landforms in a modern playa located in the West Juyan Lake, western Inner Mongolia of China, through an integrated analysis of high-resolution remote sensing images obtained from Google Earth, pedestrian field surveys, and unmanned aerial vehicle photography. The study area covers approximately 2,650 ha and the number of salt crust patches was 3,491. Across this area, the coverage and number of salt crust patches varied with elevation and sedimentary environment. The results show that the polygonal patch pattern of the salt crust landforms was fractal, and similar polygonal patch perimeter to area ratios and landscape index values prevail in the study area. The wind erosion of material on the surface of the Gobi Desert, a mountain torrent alluvial fan, and material carried by seasonal river water probably provided the provenance of the regional salt crust landforms. The structure and morphological characteristics of salt crust in typical playas of the arid and semiarid region are important for better understanding their composition and sedimentary environment. This study can help reveal relevant information regarding environmental change and provide a reference for saline dust emissions from playas in arid areas.

Strength of connection fixed by TOBs considering out-of-plane tube wall deformation-Part 1: Tests and numerical studies

Tuoya Wulan,Peijun Wang,Chengxin Xia,Xinyu Liu,Mei Liu,Fangzhou Liu,Ou Zhao,Lulu Zhang 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.42 No.1

This paper presents a study on the behavior of a bolted T-stub to square tube connection using Thread-fixed Oneside Bolts (TOBs) through tests and numerical simulations. It outlines a research work of four connections with focus on the failure modes and strengths of the connection under tensile load. It was observed that the thread anchor failure caused by shear failure of hole threads controlled the final failure of the connection in the tests. Meanwhile, the out-of-plane deformation of tube wall resulted in the contact separation between hole threads and bolt threads, which in turn reduced the shear strength of hole threads. Finite element models (FEMs) allowing for the configuration details of the TOBs fixed connection are then developed and compared with the test results. Subsequently, the failure mechanism of hole threads and stress distribution of each component are analyzed based on FEM results. It was concluded that the ultimate strength of connection was not only concerned with the shear strength of hole threads, but also was influenced by the plastic out-of-plane deformation of tube wall. These studies lay a foundation for the establishment of suitable design methods of this type of connection.

Simplified method for prediction of elastic-plastic buckling strength of web-post panels in castellated steel beams

Mei Liu,Kangrui Guo,Peijun Wang,Chao Lou,Yue Zhang 국제구조공학회 2017 Steel and Composite Structures, An International J Vol.25 No.6

Elastic-plastic shear buckling behaviors of the web-post in a Castellated Steel Beam (CSB) with hexagonal web openings under vertical shear force were investigated further using Finite Element Model (FEM) based on a sub-model, which took the upper part of the web-post under horizontal shear force to represent the whole web-post under vertical shear force. A simplified design method for the web-post elastic-plastic shear buckling strength was proposed based on simulation results of the sub-model. Proper boundary conditions were applied to the sub-model to assure that its behaviors were identical to those of the whole web-post. The equation to calculate the thin plate elastic shear buckling strength was adopted as the basic form to build the design equation for elastic-plastic buckling strength of the sub-model. Parameters that might affect the elastic-plastic shear buckling strength of the whole web-post were studied. After obtaining the vertical shear buckling strength of a sub-model through FEM, the shear buckling coefficient k can be obtained through the back analysis. A practical calculation method for k was proposed through curving fitting the parameter study results. The elastic-plastic shear buckling strength of the web-post calculated using the proposed shear buckling coefficient k agreed well with that obtained from the FEM and test results. And it was more precise than those obtained from EC3 based on the strut model.

Lab simulation of profile modification and enhanced oil recovery with a quaternary ammonium cationic polymer

Ru Qiao,Rui Zhang,Weiqun Zhu,Peijun Gong 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.1

Long-term water flooding in oilfield exploitation generally results in a marked increase of interlayer and/or inner-layer heterogeneity of oil reservoirs and premature polymer production in large quantities from flooding reservoirs. This paper presents a novel quaternary ammonium cationic polymer (NCP), which was prepared by using maize starch and (2,3-epoxypropyl)trimethylammonium chloride as raw materials. The effect of NCP on water plugging and profile modificaton after polymer HPAM (partially hydrolyzed polyacrylamide) flooding was evaluated by laboratory simulation tests of enhanced oil recovery. The experimental results indicate that crosslinking gel system formed after HPAM-NCP alternate injection could effectively seal off the high permeability zone to force the successive liquid to flow to mid-low permeability zones and get profile control in depth. In addition, the contact angle measurements reveal that the adsorption of NCP on the montmorillonite changed its surface wettability and enhanced its hydrophilicity, which promoted enhance oil recovery significantly.

Size-Controlled Self-Assembly of Superparamagnetic Polymersomes

Hickey, Robert J.,Koski, Jason,Meng, Xin,Riggleman, Robert A.,Zhang, Peijun,Park, So-Jung American Chemical Society 2014 ACS NANO Vol.8 No.1

<P>We report the size-controlled self-assembly of polymersomes through the cooperative self-assembly of nanoparticles and amphiphilic polymers. Polymersomes densely packed with magnetic nanoparticles in the polymersome membrane (magneto-polymersome) were fabricated with a series of different sized iron oxide nanoparticles. The distribution of nanoparticles in a polymersome membrane was size-dependent; while small nanoparticles were dispersed in a polymer bilayer, large particles formed a well-ordered superstructure at the interface between the inner and outer layer of a bilayer membrane. The yield of magneto-polymersomes increased with increasing the diameter of incorporated nanoparticles. Moreover, the size of the polymersomes was effectively controlled by varying the size of incorporated nanoparticles. This size-dependent self-assembly was attributed to the polymer chain entropy effect and the size-dependent localization of nanoparticles in polymersome bilayers. The transverse relaxation rates (<I>r</I><SUB>2</SUB>) of magneto-polymersomes increased with increasing the nanoparticle diameter and decreasing the size of polymersomes, reaching 555 ± 24 s<SUP>–1</SUP> mM<SUP>–1</SUP> for 241 ± 16 nm polymersomes, which is the highest value reported to date for superparamagnetic iron oxide nanoparticles.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2014/ancac3.2014.8.issue-1/nn405012h/production/images/medium/nn-2013-05012h_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn405012h'>ACS Electronic Supporting Info</A></P>

Determination of the energy contents and nutrient digestibility of corn, waxy corn and steam-flaked corn fed to growing pigs

Dongli Ma,Juntao Li,Chengfei Huang,Fengjuan Yang,Yi Wu,Ling Liu,Wei Jiang,Zhicheng Jia,Peijun Zhang,Xuezhen Liu,Shuai Zhang 아세아·태평양축산학회 2019 Animal Bioscience Vol.32 No.10

Objective: The research was conducted to determine the digestible (DE) and metabolizable energy (ME) contents as well as the apparent total tract digestibility (ATTD) of nutrients in corn, waxy corn and steam-flaked corn fed to growing pigs. Methods: Eighteen growing pigs with initial body weight of 15.42±1.41 kg were randomly allotted to three diets including a corn diet, a waxy corn diet and a steam-flaked corn diet in a completely randomized design. Each treatment contained six replicates. The experiment lasted for 12 days, which comprised 7-d adaptation to diets followed by a 5-d total collection of feces and urine. The energy contents and the nutrient digestibility in three ingredients were calculated using direct method. Results: Compared to normal corn, both the amylose and dietary fiber contents in waxy corn were numerically lower, but the starch gelatinization degree was numerically greater. Moreover, the DE and ME contents as well as the ATTD of neutral detergent fiber and acid detergent fiber (ADF) in waxy corn were significantly greater (p<0.05) than those in normal corn when fed to growing pigs. Furthermore, the steam-flaked corn had greater (p<0.05) DE and ME contents, and ATTD of ether extract and ADF compared to normal corn. Conclusion: Both variety and processing procedure have influence on chemical compositions, energy contents and nutrient digestibility of corn. The waxy corn and steam-flaked corn had greater degree of starch gelatinization and DE and ME contents compared to normal corn when fed to growing pigs.