Unmasking the reactants inhomogeneity in gas diffusion layer and the performances of PEMFC induced by assembly pressure.

The gas diffusion layer (GDL), as the bridge to reactants and electrons in PEMFC, is a carbon-based porous component and would be deformed under compression to induce changes in the distributions of reactants and the corresponding performances of PEMFC; therefore, unmasking the impacts of assembly pressure on the distribution of the reactants in GDL is significant to improve the performance of PEMFC. In the present article, the structural response of GDL to assembly pressure was first studied; the variations in transport properties of GDL and the reactant distributions induced by assembly pressure were then discussed; the impacts on the dynamic performances of PEMFC were finally investigated. From the results, assembly pressure was found to have different effects on the regions of GDL under the rib and channel, significant gaps in GDL porosity and/or GDL permeability existed near the rib/channel transition region to worsen the inhomogeneity of reactants.

Experimental analysis and safety assessment of thermal runaway behavior in lithium iron phosphate batteries under mechanical abuse.

Mechanical abuse can lead to internal short circuits and thermal runaway in lithium-ion batteries, causing severe harm. Therefore, this paper systematically investigates the thermal runaway behavior and safety assessment of lithium iron phosphate (LFP) batteries under mechanical abuse through experimental research. Mechanical abuse experiments are conducted under different conditions and battery state of charge (SOC), capturing force, voltage, and temperature responses during failure.

Effect of Mechanical Vibration on the Durability of Proton Exchange Membrane Fuel Cells.

To study the durability of proton exchange membrane fuel cells (PEMFCs), the experiments were performed by using a 300 h accelerated stress test under vibration and non-vibration conditions. Before and after chronic operation, the polarization curve, impedance spectra and cyclic voltammogram were measured at regular intervals. The voltage under vibration shows a small decline at the current density of 400 mA cm and decreases quickly along the time in high current density.

Co-Crystallization between Aliphatic Polyesters through Co-Inclusion Complexation with Small Molecule.

Crystalline/crystalline blends of polymer have shown advantages in the preparation of new polymeric materials. However, the regulation of co-crystallization in a blend is still full of challenges due to the preferential self-crystallization driven by thermodynamics. Here, an inclusion complex approach is proposed to facilitate the co-crystallization between crystalline polymers, because the crystallization process displays a prominent kinetics advantage when polymer chains are released from the inclusion complex.

Retrieval-Based Factorization Machines for Human Click Behavior Prediction.

Human click behavior prediction is crucial for recommendation scenarios such as online commodity or advertisement recommendation, as it is helpful to improve the quality and user satisfaction of services. In recommender systems, the concept of click-through rate (CTR) is used to estimate the probability that a user will click on a recommended candidate. Many methods have been proposed to predict CTR and achieved good results.

Viscoelastic Behavior and Constitutive Relation of Heavy Crude Oils.

Heavy crude oil exhibits very complex viscoelastic behaviors due to its complex composition of resins, asphaltenes, saturates, and aromatics. It has a great influence on oil production and transportation. In this work, the viscoelastic behaviors of three different heavy crude oils were measured using a rotational rheometer.

Understanding mechanisms of shape memory function deterioration for nitinol alloy during non-equilibrium solidification by electron beam.

Introduction: As an important advanced functional material, the memory effect of nitinol shape memory alloy (SMA) is the focus of research. According to the current research, the memory function of the alloy decreases after welding, and there is no sufficient explanation for the phenomenon.

Objectives: For the problem, this research is to explore the underlying causes of the decrease of shape memory function after welding by analyzing the microstructure and micro defects.

Microencapsulated Phase Change Material Suspension for Cold Start of PEMFC.

We added microencapsulated phase change materials (MPCMs) into the homemade antifreeze fluid to take advantage of the latent heat of phase change materials, and explored the possibility of solving the cold start problem of proton exchange membrane fuel cells (PEMFC) with variable specific heat capacity antifreeze. The physical and chemical properties of the MPCMs and their suspensions were tested, and a PEMFC platform for cold start with a thermal management system was established to compare the exothermic performance of MPCS and commercial antifreeze fluid. According to the output voltage, temperature and polarization curves before and after cold start, the MPCMs has a stronger heat transfer capacity than the commercial antifreeze fluid, and the addition of MPCMs can transform the latent heat generated during the phase transition into apparent specific heat capacity, leading to a better solution to the problem of PEMFC cold start.

Preliminary Investigations of an Opposed Rotary Piston Compressor for the Air Feeding of a Polymer Electrolyte Membrane Fuel Cell System.

Automotive polymer electrolyte membrane fuel cell systems are attracting much attention, driven by the requirements of low automotive exhaust emissions and energy consumption. A polymer electrolyte membrane fuel cell system provides opportunities for the developments in different types of air compressors. This paper proposed an opposed rotary piston compressor, which had the merits of more compact structures, less movement components, and a high pressure ratio, meeting the requirements of polymer electrolyte membrane fuel cell systems.

A Study on the Mechanical Characteristics and Self-Preservation Performance of a Deployment Mechanism with a Large Exhibition Ratio during Its Gathering Process.

In order to study the stress state and stability of a spiral tube and actuator for controlled extension and retraction (STACER) during the launching process of a satellite, finite element software was applied to establish a finite element model of STACER via the explicit dynamics analysis method. The influence of top rod's radius on the gathering or so called packaging process of STACER was analyzed. The effects of surface friction coefficient and acceleration on the stability were studied during the gathering process.

Optimization and testing of suspension system of electric mini off-road vehicles.

Mini vehicles with a small wheelbase are extremely sensitive to road roughness. The aim of this study is to explore the influence of road information on ride comfort and enhance the ride comfort of mini vehicles. According to the 5-degree-of-freedom vibration model of an electric mini off-road vehicle, the partial differential matrix equation of system motion is established using the Lagrange method, and the frequency response characteristic of the system is analyzed.

Differences in Dry Sliding Wear Behavior between Al-12Si-CuNiMg Alloy and Its Composite Reinforced with AlO Fibers.

The dry sliding wear behavior of the Al-12Si-CuNiMg matrix alloy and its composite reinforced with AlO fibers was investigated using a pin-on-disk wear-testing machine. The volume fraction of AlO fibers in the composite was 17 vol.%.

A novel guidance law using fast terminal sliding mode control with impact angle constraints.

This paper is concerned with the question of, for a missile interception with impact angle constraints, how to design a guidance law. Firstly, missile interception with impact angle constraints is modeled; secondly, a novel guidance law using fast terminal sliding mode control based on extended state observer is proposed to optimize the trajectory and time of interception; finally, for stationary targets, constant velocity targets and maneuvering targets, the guidance law and the stability of the closed loop system is analyzed and the stability of the closed loop system is analyzed, respectively. Simulation results show that when missile and target are on a collision course, the novel guidance law using fast terminal sliding mode control with extended state observer has more optimized trajectory and effectively reduces the time of interception which has a great significance in modern warfare.

Impact angle constrained three-dimensional integrated guidance and control for STT missile in the presence of input saturation.

Considering a class of skid-to-turn (STT) missile with fixed target and constrained terminal impact angles, a novel three-dimensional (3D) integrated guidance and control (IGC) scheme is proposed in this paper. Based on coriolis theorem, the fully nonlinear IGC model without the assumption that the missile flies heading to the target at initial time is established in the three-dimensional space. For this strict-feedback form of multi-variable system, dynamic surface control algorithm is implemented combining with extended observer (ESO) to complete the preliminary design.