Preparation and properties of high-strength-high-modulus polyimide cords/natural rubber composites

High-strength-high-modulus polyimide (PI) cords reinforced natural rubber (NR) composites are prepared, and the PI cords are treated with resorcinol-formaldehyde-latex (RFL) adhesive to enhance the interfacial adhesion with NR matrix. The influence of RFL adhesive variables, such as the ratio of R/F and RF/L, on the adhesion between PI cords and NR is investigated. Furthermore, sorbitol glycidyl ether (SGE) and caprolactam blocked methylene diisocyanate (CBI) are adhered to the surface of the PI cords through a dip-coating procedure to introduce epoxy and NCO groups and graft with more RFL adhesive. The H pull-out force of SGE/CBI-RFL treated PI cords/NR composites reaches as high as 193.9 N, which is 580% higher than that of untreated PI ones. Additionally, the SGE/CBI-RFL treated PI cords/NR composites exhibit superior adhesion, aging, and fatigue resistance together with better mechanical properties as compared with SGE/CBI-RFL treated poly(para-phenylene terephtalamide) (PPTA) cords/NR composites.     

Exponential Set-Point Stabilization of Underactuated Vehicles Moving in Three-Dimensional Space

This paper investigates the stabilization of underactuated vehicles moving in a three-dimensional vector space. The vehicle’s model is established on the matrix Lie group SE(3), which describes the configuration of rigid bodies globally and uniquely. We focus on the kinematic model of the underactuated vehicle, which features an underactuation form that has no sway and heave velocity. To compensate for the lack of these two velocities, we construct additional rotation matrices to generate a motion of rotation coupled with translation. Then, the state feedback is designed with the help of the logarithmic map, and we prove that the proposed control law can exponentially stabilize the underactuated vehicle to the identity group element with an almost global domain of attraction. Later, the presented control strategy is extended to set-point stabilization in the sense that the underactuated vehicle can be stabilized to an arbitrary desired configuration specified in advance. Finally, simulation examples are provided to verify the effectiveness of the stabilization controller.      

A Hydro-Economic Model for Optimizing Management of Mine Water: A Case Study in the Suancigou Coal Mine,Northwestern China

Mine Water and the Environment - Comprehensive analysis of hydrogeological conditions at a typical coal mine in northwestern China allowed us to establish a groundwater numerical model, which we...     

Object matching between visible and infrared images using a Siamese network

Applied Intelligence - In this study, we propose a method for object matching between visible and infrared images. We consider object matching between visible and infrared images as a computational...     

基于云计算的煤矿信息数据管理系统

近年来,随着云计算技术的迅速发展,其在煤矿领域的应用需求也日益突出。该文从煤炭企业的信息数据入手,介绍了云计算的概念和特点,研究了其与传统企业信息化技术相比的功能优势,并深入探讨了云计算在现代化矿井中如何加以应用。     

建构主义理论指导下化工原理课程教学的思考及实践

建构主义理论是认知主义理论的深化及发展,其从认知结构上揭示了个体学习发生的内部机制,在教育教学中日益得到重视及应用。理工性质的化工原理课程的内容是应用数学、物理和化学等自然科学理论研究实际化学工程中的普遍规律,并解决化工过程设计和设备计算。我院在该课程的教学设计和教学实施过程中,以建构主义理论为指导,明确学生地位和教师地位,做好各级教学设计,在展现教学内容的方法和步骤等方面做了细致的思考及教学实践。     

Study on a new air-gap membrane distillation module for desalination

A new air-gap membrane distillation (AGMD) module for desalination with internal latent-heat-recovery which consisted of parallel hollow fiber membranes and heat exchange hollow fibers was successfully developed. The influences of feed flow rate, feed temperature and feed initial concentration on AGMD process were investigated. The vapor pressure polarization coefficient (η) was introduced to measure the reduction in the effective driving force for mass transfer with regard to the driving force imposed. Among all AGMD experiments, the maximum water vapor permeate flux (J_D) of 5.30 kg/m² h and the gained output ratio (GOR) of 5.70 were obtained. A theoretical model based on the mass and energy balances of the hot feed side was established to calculate the temperature and the local water vapor permeate flux distributions along the hollow fiber membrane, which showed that the temperature drop and local water vapor permeate flux drop were much larger at the upper part than those at the lower part of the membrane module in the hot feed side.     

Synthesis and characterization of advance PA6‐b‐PDMS multiblock copolymers

Advance polyamide‐6‐b‐polydimethylsiloxane (PA6‐b‐PDMS) multiblock copolymers were first synthesized via the polymerization in bulk. Binary carboxyl terminated PA6 was served as the hard segment and PDMS modified with hexamethylene diisocyanate (PDMS‐NCO) was the soft segment. A series of PA6‐b‐PDMS copolymers based on different content and length of soft segments were obtained. Interestingly, Differential scanning calorimetry (DSC) studies revealed no obvious change in melting temperature after introducing PDMS segments to copolymers. The high melting temperatures indicated these copolymers possess potential applications in automotive industry that require high continuous use temperatures. DSC and transmission electron microscopy studies both demonstrated increasing the length and the content of the soft segment contributed to increasing of the degree of microphase separation. However, the improvement of thermal stability resulting from PDMS segments was also observed by thermo gravimetric analysis. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41114.     

Evaluate the nonlinear viscoelasticity of polyolefin melts using the Larson model

Nonlinear rheological properties of polyolefins have long been studied and predicted by using the Larson model with the damping function generally obtained from the stress relaxation measurements. In this study, we investigate the nonlinear rheological properties of high density polyethylene (HDPE) and polypropylene (PP) using the Larson model with damping functions obtained from either the dynamic frequency sweep or the stress relaxation test. Experimental measurements and their corresponding model predictions for the rheological parameters were then compared to evaluate the applicability of the Larson model to the nonlinear rheology, and the following conclusions could be achieved. The steady shear viscosity could be satisfactorily described by the Larson model with the damping functions obtained from the two different methods, except at shear rates higher than 10³ s^?1. The predicted first normal stresses also account for the measured data, except for those using the stress relaxation data showing a little deviation for the PP sample. In addition, the predictions for elongation viscosity are also in good agreement with the experimental results within the short range of elongation rate achieved in this work. POLYM. ENG. SCI., 54:2354–2361, 2014. © 2013 Society of Plastics Engineers     

Hierarchical mullite structures and their heat-insulation and compression–resilience properties

Near-net-shaped hierarchical structure-adjustable short mullite fibers/mullite whiskers frameworks (MF/MW frameworks) were prepared by slurry-filtration and heat-treating method. The main structure of MF/MW framework was constituted by lap-jointed mullite fibers. Every single fiber in the framework was densely covered by mullite whiskers which formed through fluorine-catalyzed gas-phase reaction, and the fibers actually served as curved substrates for the mullite whiskers' growth. The lap-jointing points of the fibers were served by movable intersected mullite whiskers. Moreover, the microstructure of the frameworks could be adjusted by tailoring the raw materials mass ratio. The volume densities, the apparent porosities and the thermal conductivities of the MF/MW frameworks in different raw materials mass ratios were 0.459–0.487 g/cm³, 79.7–82.8% and 0.1356–0.1965 W/k m, respectively. The compression–resilience property of the samples was tested under 0.4 MPa at room temperature. The compression ratio and resilience ratio of the MF/MW frameworks in different raw materials mass ratios were 1.63–2.25% and 92.67–98.16%, respectively. The MF/MW frameworks with advanced thermal and mechanical properties were considered to be promising high-temperature heat-insulation material.