Energy management of fuel cell/solar cell/supercapacitor hybrid power source

This study presents an original control algorithm for a hybrid energy system with a renewable energy source, namely, a polymer electrolyte membrane fuel cell (PEMFC) and a photovoltaic (PV) array. A single storage device, i.e., a supercapacitor (ultracapacitor) module, is in the proposed structure. The main weak point of fuel cells (FCs) is slow dynamics because the power slope is limited to prevent fuel starvation problems, improve performance and increase lifetime. The very fast power response and high specific power of a supercapacitor complements the slower power output of the main source to produce the compatibility and performance characteristics needed in a load. The energy in the system is balanced by d.c.-bus energy regulation (or indirect voltage regulation). A supercapacitor module functions by supplying energy to regulate the d.c.-bus energy. The fuel cell, as a slow dynamic source in this system, supplies energy to the supercapacitor module in order to keep it charged. The photovoltaic array assists the fuel cell during daytime. To verify the proposed principle, a hardware system is realized with analog circuits for the fuel cell, solar cell and supercapacitor current control loops, and with numerical calculation (dSPACE) for the energy control loops. Experimental results with small-scale devices, namely, a PEMFC (1200 W, 46 A) manufactured by the Ballard Power System Company, a photovoltaic array (800 W, 31 A) manufactured by the Ekarat Solar Company and a supercapacitor module (100 F, 32 V) manufactured by the Maxwell Technologies Company, illustrate the excellent energy-management scheme during load cycles.     

Photocatalytic performance of CdS nanomaterials for photodegradation of organic azo dyes under artificial visible light and natural solar light irradiation

The CdS semiconductors have been prepared at low temperature via catalyst-free chemical precipitation method without using any surfactant or capping agent. Either water or ethylene glycol, as a solvent, provides spherical CdS nanostructures with a comparable size of 117–121 nm. The molar ratio of Cd/S plays an important role in determining phase structure, morphology and photocatalytic performance of the prepared CdS nanostructures. Increasing molar ratio of S^2? results in not only mixed cubic-hexagonal phases but also low photocatalytic performance. CdS nanoparticles with good dispersibility prepared at Cd/S molar ratio of 1:1 shows high photocatytic efficiency of 95% toward photodegradation of reactive red azo dye (RR141) under visible light irradiation up to 240 min. The degradation efficiency of CdS nanoparticles also reaches 48% under natural solar light irradiation for 80 min. This work demonstrates the promising potential of CdS nanomaterials as photocatalysts for environmental remediation.     

The use of FEA and design of experiments to establish design guidelines for simple hydroformed parts

We present models to predict the protrusion height of “Tee-shaped” hydroformed parts, both because this information is of direct relevance to engineers attempting to build such parts and also to illustrate an advantageous process for developing design guidelines for tube hydroforming (THF) in general. A newly proposed design of experiments technique, Low Cost Response Surface Method (LCRSM), was utilized to facilitate the economical prediction and optimization of this height as a function of geometrical parameters subject to thinning of the wall thickness at the protrusion region. The same methodology is also proposed for the economical investigation of other geometries and conditions. As a result of this investigation, not only were known and expected trends of effect of parameters verified, but also numerical values within a practical range of parameters at certain conditions were obtained. In addition, interactions between factors were also revealed as predicted. Moreover, this information was gained from a substantially reduced number of finite element analysis (FEA) simulations via LCRSM compared to standard response surface method (RSM) or factorial techniques, avoiding costly physical experimentation.     

Performance Analysis for Asynchronous Requests in Wireless Networks with Multiple Packet Reception Capability

Wireless Personal Communications - Fifth generation (5G), the currently evolving communication standard, promises better performance in terms of capability, capacity, speed, latency, etc. than...     

Crack initiation and propagation of galvanized coatings hot-dipped at 450 °C under bending loads

Crack initiation and propagation behaviors in the intermetallic layers of galvanized coatings subjected to bending loads are characterized and numerically simulated. Coating structure of galvanized steel prepared by hot dipping at 450 °C is a laminate composite consisting of δ, ζ, and η phases, with an infinitesimal layer between the coating and steel article speculatively representing a Γ phase. The specimens were deformed in a four-point bending configuration, and the evolution of cracks was investigated as a function of bending angles. Through-cracks were found to develop in the δ layer of the coatings after thermal cooling due to thermal stresses and propagate toward the outer surface under increments of bending loads. Finite element simulations of galvanized steels were subsequently developed with an initial crack tip located in the δ layer to determine the controlling parameters of the crack propagation and to assess the coatings' fracture parameter, critical far field stress, and stress distributions. The analysis highlights the enhancement of fracture resistance of the galvanized coatings owing to the presence of the ζ layer.     

Influence of Pre-Deformation on Springback Effect of Advanced High Strength Steel

In sheet metal forming process of automotive components,the springback effect is significant,in particular for Advanced High Strength Steels (AHSS),for example the Dual Phase (DP) steel.Most of construction parts of modern vehicles have very complex shapes and therefore multi-step procedures are necessary to form such a part.Steel sheets,which firstly undergo pre-deformation,can show considerable change in mechanical behavior during the forming process.However,at present there are limited sufficient data concerning pre-deformation effect on the springback available.In this work,a study of influences of different pre-strain levels on the springback of steel sheet made of AHSS materials has been carried out.The sheet specimens were firstly pre-stretched on a tensile testing machine and the pre-strain values were calculated based on the engineering strain.Furthermore,the steel sheets prepared parallel,transverse,and 45° to the rolling direction have been investigated.A modified U-shape forming was used to evaluate the degree of springback of the steel sheets under various conditions.In parallel,FE simulation of the U-shape forming was performed.Both isotropic model using stress-strain responses from tensile test of specimens with different directions and anisotropic Hill’s 48 model have been applied.The experimental results are compared with the sheet metal forming FE simulations.The primarily aim is to basically understand the springback mechanism by means of the simple models.And finally,conclusions with regard to the springback modeling will be presented.     

Robust synchronization of fractional-order unified chaotic systems via linear control

A new scheme for accomplishing synchronization between two fractional-order unified chaotic systems is proposed in this paper. The scheme does not require that the nonlinear dynamics of the synchronization error system must be eliminated. Moreover, the parameter of the systems does not have to be known. A controller is a linear feedback controller, which is simple in implementation. It is designed based on an LMI condition. The LMI condition guarantees that the synchronization between the slave system and the master system is achieved. Numerical simulations are performed to demonstrate the effectiveness of the proposed scheme.     

Polyurethane foams from oligomers derived from waste tire crumbs and polycaprolactone diols

This work was an initial study on the synthesis of polyurethane foams (PUF) by using diols obtained from the controlled degradation of waste tire crumbs and from polycaprolactone (PCL) followed by examination of their biodegradability. Natural rubber (NR, cis?1,4 polyisoprene) and butadiene rubber (BR) chains contained in waste tire crumbs were chemically modified into carbonyl telechelic (CTWT) and successively into hydroxyl telechelic oligomers (HTWT). Four types of PUF were prepared with different molar ratios between the HTWT and the PCL diols. CTWT and HTWT were analyzed by ¹H‐NMR, SEC, and FT‐IR to confirm their chemical structure. Formation of the urethane bond was demonstrated by FT‐IR spectra. The addition of the PCL diol increased the thermal degradation temperature of the PUF based on thermogravimetric analysis. According to scanning electron microscopy, polyhedral closed cells were obtained. The molar ratio of HTWT/PCL diols strongly affected the kinetic rate of foam formation and foam morphology. A low kinetic rate provided PUF with a high density, small cell size, and a broad cell size distribution. In order to assess biodegradation of PUF, the modified Sturm test was carried out for 60 days at ambient temperature (27–30 °C). The biodegradation of PUF containing only HTWT was 31.2% and 51.3% at 28 days and 60 days of testing, respectively whereas the PUF containing 1/0.5 HTWT/PCL diols (by mole) showed a higher biodegradation: 39.1% and 64.3% at 28 days and 60 days of testing respectively. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44251.     

A third-order sliding mode controller for nonlinear multivariable systems

This paper proposes a third-order sliding mode controller for nonlinear multivariable systems with uncertain parameters and subject to external disturbances. The controller achieves fast convergence rate, high tracking accuracy, and a reduced level of chattering. The stability of the controller and its global ultimately uniform convergence is proved by the Lyapunov stability theory. Simulation results on a single inverted pendulum system are given to illustrate the effectiveness of the proposed control scheme by comparing it with methods such as a second-order supertwisting controller, a third-order supertwisting controller, and an integral terminal third-order sliding mode controller.     

Graphene-Based RFID Tag Antenna for Vehicular Smart Border Passings

Globalization has opened practically every country in the globe to tourism and commerce today. In every region, the volume of vehicles traveling through border crossings has increased significantly. Smartcards and radio frequency identification (RFID) have been proposed as a new method of identifying and authenticating passengers, products, and vehicles. However, the usage of smartcards and RFID tag cards for vehicular border crossings continues to suffer security and flexibility challenges. Providing a vehicle's driver a smartcard or RFID tag card may result in theft, loss, counterfeit, imitation, or vehicle transmutation. RFID sticker tags would replace RFID tags as vehicle border passes to solve the mentioned problem. The RFID sticker tag adheres to the windscreen, side screen, dash, hood, or door of the vehicle, or any other acceptable location. Any damage or stripping from the installed location may cause data corruption and cannot be reused. Overall, these sticker tags will make the border crossings more secure and efficient. This article focuses on designing a rectangular-shaped RFID sticker tag antenna made of graphene sheets as a possible solution for smart border crossings. The proposed antenna is mathematically designed and analyzed with CST software to determine the optimum parameters. The design parameters are then used to create an antenna on a prepared graphene sheet. The performance results are carried out with CST software and a network analyzer. The designed RFID antenna stick on a car windscreen offers approximately 900 MHz bandwidth over the frequency range from 1.8 GHz to 2.7 GHz with an average gain of 1.23 dBi at the frequency to be used of 2.4 GHz microwave RFID band. The radiation is an omnidirectional pattern. The proposed graphene-sheet rectangular-shape monopole antenna is compact, low-cost, and bendable to fit into the windscreen of a car while retaining excellent wave propagation capabilities. These findings illustrate the suggested antenna's potential as an RFID tag antenna in a vehicular smart border pass system.