Transient response of a polymer electrolyte membrane fuel cell subjected to modulating cell voltage

This paper presents a computational investigation of the effect of time‐varying modulating conditions on a polymer electrolyte membrane fuel cell. The focus is on developing a better understanding of the fuel cell's water balance under transient conditions, which is critical in improving the fuel cell design. The study employs a macroscopic single‐fuel cell‐based, one‐dimensional, isothermal model. The model does not rely on the non‐physical assumption of the uptake curve equilibrium between the pore vapor and ionomer water in the catalyst layers. Instead, the transition between the two phases is modeled as a finite‐rate equilibration process. The modulating conditions are simulated by forcing the temporal variations in fuel cell voltage. The results show that cell voltage modulations cause a departure in the cell behavior from its steady behavior, and the finite‐rate equilibration between the catalyst vapor and liquid water can be a factor in determining the cell response. The cell response is also affected by the modulating frequency and amplitude. The peak cell response is observed at low frequencies. Copyright © 2011 John Wiley & Sons, Ltd.     

Optimum packet size for data networks with random channel errors

The formula for the optimum packet size required for maximum utilisation of network lines can be derived in several different ways, under a usual assumption of error-free transmission lines/channels. An analysis based on the concept of minimisation of network overheads is used to derive the optimum packet size for lines having random-error characteristics. The messages are assumed to have a Poisson distribution, and the network uses a stop-and-wait strategy for error detection and correction.     

Dispersion-tolerant transmission using a duobinarypolarization-shift keying transmission scheme

We demonstrate a novel dispersion-tolerant transmission scheme based on a three-level duobinary-encoded polarization-shift keying (PoISK) transmission format. Simulations over standard single-mode fiber demonstrate an improvement in the chromatic dispersion-limited transmission distance from ~65 km, using conventional nonreturn to zero intensity modulation to ~195 km for duobinary PoISK     

Effect of temperature on wastewater treatment with natural and waste materials

The effect of temperature on the wastewater treatment with waste materials (refuse concrete and refuse waste) and natural material (shell) was investigated. The removal of suspended solid (SS), phosphate ion, nitrate ion, ammonium ion and chemical oxygen demand (COD) were evaluated for the temperature effect. Although the extensive improvement of removal efficiencies for nitrate ion and ammonium ion could not be achieved by increasing the temperature, the significant enhancement of the removal of SS and COD was observed. The present wastewater treatment system is simple, convenient and low-cost. Therefore, the developed methods can be applied to the small-scale plant for the wastewater treatment in the local and nonexclusive areas.     

Cloud-Assisted Mood Fatigue Detection System

This paper introduces basic concept of mood fatigue detection and existing solutions as well as some typical solutions, such as mobile sensing and cloud computing technology. In the first place, we sum up main challenges of mood fatigue detection and the direction of future study. Then one type of system implementation is put forward, such system consists of: 1) Wearable devices used to detect the users’ mood fatigue; 2) Clouds data center; 3) Application and service manager. We take overall consideration of many factors like the user’s physiological information, external environment conditions and user behavior, evaluate accurately through big data analytic technology the users’ state of mood fatigue and to what extent shall one keeps vigilant as well as what measures shall be adopted to improve the users’ working performance and alert the users to keep themselves away from the danger. Finally a real system is established in this paper, it is composed of the smart clothing, cloud platform and mobile terminal application.     

Experimental and theoretical investigation of micellization behavior of sodium dodecyl sulfate with cetyltrimethylammonium bromide in aqueous/urea solution at various temperatures

Mixed micelle formation behavior of cationic surfactant-cetyltrimethylammonium bromide (CTAB) and anionic surfactant sodium dodecyl sulfate (SDS) in aqueous as well as in urea medium from 303.15 K to 323.15 K at 5 K interval was carried out by conductometric method. The differences between the experimental values of critical micelle concentrations (cmc) and ideal critical micelle concentrations (cmc^id) illustrate the interaction between the amphiphiles studied. The values of micellar mole fraction (\(\text{X}_1^{Rub}\) (Rubingh), \(\text{X}_1^{M}\) (Motomura), \(\text{X}_1^{Rod}\)(Rodenas) and \(\text{X}_1^{id}\)(ideal) of surfactant CTAB determined by different proposed models and outcome indicate high involvement of CTAB in SDS-CTAB mixed micellization, which enhance by means of the augment of mole fraction of CTAB. The negative value of interaction parameter (β) showed an attractive interaction involving CTAB and SDS. Activity coefficients were less than unity in all case, which also reveals the presence of interaction between CTAB & SDS. The negative \(\Delta{\text{G}}_m^0\)values imply the spontaneous mixed micellization phenomenon. The attained values of \(\Delta{\text{H}}_m^0\)were positive at inferior temperature, while negative at superior temperature. The negative \(\Delta{\text{H}}_m^0\)values in urea (NH₂CONH₂) medium illustrate exothermic micellization process. The magnitudes of \(\Delta{\text{S}}_m^0\)were positive in almost all cases. The excess free energy of mixed micelle formation (ΔG_ex) was found to be negative, which indicates the stability of mixed micelle as compared to the individual’s components micelles.     

Cooperative game-based distributed resource allocation in horizontal dynamic cloud federation platform

Distributed resource allocation is a very important and complex problem in emerging horizontal dynamic cloud federation (HDCF) platforms, where different cloud providers (CPs) collaborate dynamically to gain economies of scale and enlargements of their virtual machine (VM) infrastructure capabilities in order to meet consumer requirements. HDCF platforms differ from the existing vertical supply chain federation (VSCF) models in terms of establishing federation and dynamic pricing. There is a need to develop algorithms that can capture this complexity and easily solve distributed VM resource allocation problem in a HDCF platform. In this paper, we propose a cooperative game-theoretic solution that is mutually beneficial to the CPs. It is shown that in non-cooperative environment, the optimal aggregated benefit received by the CPs is not guaranteed. We study two utility maximizing cooperative resource allocation games in a HDCF environment. We use price-based resource allocation strategy and present both centralized and distributed algorithms to find optimal solutions to these games. Various simulations were carried out to verify the proposed algorithms. The simulation results demonstrate that the algorithms are effective, showing robust performance for resource allocation and requiring minimal computation time.     

An end-to-end deep learning model for human activity recognition from highly sparse body sensor data in Internet of Medical Things environment

The Journal of Supercomputing - Recognizing human activity from highly sparse body sensor data is becoming an important problem in Internet of Medical Things (IoMT) industry. As IoMT currently uses...     

Enhancing lifetime of visual sensor networks with a preprocessing-based multi-face detection method

Recently, advances in hardware such as CMOS camera nodes have led to the development of Visual Sensor Networks (VSNs) that process sensed data and transmit the useful information to the base station for completing subsequent tasks. Today, object detection and sending useful information to the base station for object recognition is emerged as an important challenging issue in VSNs. Our investigations show that the face’s information is adequate for completing object recognition. According to literature, many approaches have been proposed for object detection and sending useful information to the base station to be completed subsequent tasks like object recognition. However, in most of them, lack of preprocessing methods in camera nodes causes network to be faced with large volume of data. For example when there is more than one object within the each camera node filed-of-view, conventional works deliver empty spaces among objects to the base station. Also, most of them send whole information about each object to the base station, while sending only face’s information of each object is adequate for completing object recognition. Therefore, in this paper, a preprocessing method in camera nodes named Preprocessing-based Multi-Face Detection (PMFD) is proposed. Our method works based on the extracting bounding box of each object’s face, using Boosting-based face detection algorithm, and sending only the faces’ information to the base station. The simulation results show that PMFD method has acceptable preprocessing time complexity and injects low volume of traffic into the network. Consequently, PMFD method prolongs the network lifetime in comparison with state-of-the-art algorithms.