Automotive carbon fiber: Opportunities and challenges

The carbon fiber industry is growing, with steadily increasing demand from the aerospace and defense markets as well as smaller markets such as sporting goods and construction materials. Infiltration of the automotive market remains a challenge, however, and so the U.S. Department of Energy's (DOE) FreedomCAR program has made the development of low-cost automotivegrade carbon fiber its highest priority for materials research. The DOE effort is currently focused on three objectives: developing low-cost carbon fiber precursors, low-cost conversion methods, and high-throughput fabrication processes.     

New dye-sensitized solar cells obtained from extracted bracts of bougainvillea glabra and spectabilis betalain pigments by different purification processes

The performance of a new dye-sensitized solar cell (DSSC) based in a natural dye extracted from the Bougainvillea spectabilis' bracts, is reported. The performance of this solar cell was compared with cells prepared using extract of the Bougainvillea glabra and mixture of both extracts; in both cases the pigments were betalains, obtained from Reddish-purple extract. These dyes were purified to different extents and used for the construction of solar cells that were electrically characterized. The materials were characterized using FTIR and UV-Vis. Solar cells were assembled using TiO(2) thin film on indium tin oxide (ITO)-coated glass; a mesoporous film was sensitized with the Bougainvillea extracts. The obtained solar energy conversion efficiency was of 0.48% with a current density J(SC) of 2.29 mA/cm(2) using an irradiation of 100 mW/cm(2) at 25 °C.     

Robustness of a methodology for estimating hourly energy consumption of buildings using monthly utility bills

The evaluation of building energy consumption under typical meteorological conditions requires building energy profiles on an hourly basis. Computer simulations can be used to obtain this information, but generating simulations requires a significant amount of experience, time, and effort to enter detailed building parameters. This paper considers a simple methodology for using existing EnergyPlus benchmark building energy profiles to estimate the energy profiles of buildings with similar characteristics to a given benchmark model. The method utilizes the building monthly energy bills to scale a given benchmark building energy profile to approximate the real building energy profile. In particular, this study examines the robustness of the methodology considered with respect to the parameter discrepancies between a given building and the corresponding EnergyPlus benchmark model used to estimate its profile. Test buildings are defined by perturbing several combinations of the parameters defined in the benchmark building model. The test buildings examined are similar to the EnergyPlus, medium sized office, benchmark building in Baltimore, MD, and a total of 72 distinct test building configurations are examined. The analysis reveals that the methodology can significantly reduce the errors introduced by discrepancies from the EnergyPlus benchmark model.     

Effects of High-Intensity Pulsed Electric Fields Processing Parameters on the Chlorophyll Content and Its Degradation Compounds in Broccoli Juice

The influence of high-intensity pulsed electric fields (HIPEF) parameters including electric field strength (15–35 kV/cm), treatment time (500–2,000 μs), and polarity (monopolar or bipolar mode) on the content of chlorophylls (Chls), pheophytin (Phe), chlorophyllide (Chlide), and pheophorbide (Phb) and chlorophyllase activity (Chlase) in broccoli juice were assessed. A significant effect of HIPEF parameters on Chlase, Chls, and Chls degradation compounds was observed through a response surface methodology design. However, polarity did not exert influence neither on Chl a nor on Chl b. The optimum HIPEF treatment was found to be 35 kV/cm for 1,980 μs in bipolar mode, where the highest content of Chls was kept, the lowest Chlase residual activity was reached, and the minimal quantities of Chls degradation compounds content were formed. Additionally, at these HIPEF conditions, broccoli juice exhibited greater content of Chls than thermally treated or untreated juice. These outcomes demonstrated that HIPEF processing could be a suitable technology to maintain the Chls content in broccoli juice.     

BATCH VIBRATING FLUID BED DRYER FOR SAWDUST PARTICLES: EXPERIMENTAL RESULTS

ABSTRACT

In a batch experimental equipment, the behavior of a sawdust dryer in a vibrating fluidized bed is analyzed. Empirical data concerning fluidization velocities, pressure drops and drying kinetics was obtained, and advantages of using vibration in the drying chamber, relative to a conventional fluidized bed, are shown. This technique is presented as an alternative to solve problems of solid agglomeration and bed defluidization. Results show that it is possible to dry sawdust with more than 2 kg/kg moisture, in a vibrating bed keeping a high degree of bed homogeneity and high quality of fluidized state.     

Sizing analysis of a combined cooling,heating, and power system for a small office building using a wood waste biomass‐fired Stirling engine

When wood chips are available and used to fuel a combined cooling, heating, and power (CCHP) waste heat recovery system, they can represent an economically viable source of biomass energy that can meet a facility's electric and thermal demands. Using a Stirling engine as the CCHP prime mover provides several important advantages over conventional internal combustion engines including no additional processing of the waste wood chips, a potentially higher thermal efficiency, flexibility of fuel sources, and low maintenance. This study shows how the operational characteristics of a constant output, biomass‐fired, Stirling engine‐based CCHP system are affected by the performance of the individual components, including the prime mover, heat recovery system, auxiliary boiler, absorption chiller, and heating coil unit The results are assessed by examining the primary energy consumption and operational cost compared with a reference case. The analysis provides insight on the prime mover sizing and selection of each component to properly implement the system. In addition to examining the effects of each component, the effect of excess electricity production and buyback are considered. Copyright © 2010 John Wiley & Sons, Ltd.     

A Clustered-Based Categorization of Millennials in their Technology Behavior

There is an increasing interest for millennials; however, to date, millennials’ segmentations regarding their technology behavior are scarce. This study addresses the following questions: “Are there segments within this generation group regarding their digital technology behavior?”. And if so: “Are there variances in the way that millennial segments use digital technology?”; and further: “What are the main differences among millennial segments regarding their technology behavior?”.

Data from a sample of 707 millennials were analyzed through principal components and cluster analysis. Then, millennials’ segments were profiled using a multivariate analysis of variance (MANOVA) analysis. Findings revealed that not every millennial has the same technology use and behavior. Moreover, there are five clustered-based segments of millennials regarding their technology behavior: technology devotees, technology spectators, circumspects, technology adverse users, and productivity enhancers. This study contributes with a detailed perspective of how different millennial segments use digital technology.     

Mini Rotorcraft Flight Formation Control Using Bounded Inputs

In this paper, the flight formation control and trajectory tracking control design of multiple mini rotorcraft systems are discussed. The dynamic model of a mini rotorcraft is presented using the Newton-Euler formalism. Our approach is based on a leader/follower structure of multiple robot systems. The centroid of the coordinated control subsystem is used for trajectory tracking purposes. A nonlinear controller based on separated saturations and a multi-agent consensus algorithm is developed. The analytic results are supported by simulation tests. Experimental results include yaw coordination and tracking only.     

Experimental Pulmonary Tuberculosis in the Absence of Detectable Brain Infection Induces Neuroinflammation and Behavioural Abnormalities in Male BALB/c Mice

Tuberculosis (TB) is a chronic infectious disease in which prolonged, non-resolutive inflammation of the lung may lead to metabolic and neuroendocrine dysfunction. Previous studies have reported that individuals coursing pulmonary TB experience cognitive or behavioural changes; however, the pathogenic substrate of such manifestations have remained unknown. Here, using a mouse model of progressive pulmonary TB, we report that, even in the absence of brain infection, TB is associated with marked increased synthesis of both inflammatory and anti-inflammatory cytokines in discrete brain areas such as the hypothalamus, the hippocampal formation and cerebellum accompanied by substantial changes in the synthesis of neurotransmitters. Moreover, histopathological findings of neurodegeneration and neuronal death were found as infection progressed with activation of p38, JNK and reduction in the BDNF levels. Finally, we perform behavioural analysis in infected mice throughout the infection, and our data show that the cytokine and neurochemical changes were associated with a marked onset of cognitive impairment as well as depressive- and anxiety-like behaviour. Altogether, our results suggest that besides pulmonary damage, TB is accompanied by an extensive neuroinflammatory and neurodegenerative state which explains some of the behavioural abnormalities found in TB patients.     

Influence of monomeric concentration on mechanical and electrical properties of poly(styrene-co-acrylonitrile) and poly(styrene-co-acrylonitrile/acrylic acid) yarns electrospun

Two series of copolymers were synthesized by emulsion polymerization: poly(styrene-co-acrylonitrile) P(S:AN) and P(S:AN-acrylic acid) P(S:AN-AA). The monomeric concentrations in both series were: 0:100, 20:80, 40:60, 50:50 (wt%:wt%), and 1 wt% of AA. The copolymers were dissolved in N,N-dimethylformamide (4–10 wt%) and were electrospun. Polymeric yarns were collected using a blade collector. The synthesized and fabricated materials were characterized by known techniques. Mechanical and electrical properties of polymeric yarns indicated a dependence of monomeric concentration. Elastic modulus increases as acrylonitrile concentration increases (up to 30 MPa). Yarns were submitted to degradation process into saline solution, where the acrylic acid content kept a constant elastic modulus at long times. The electrical current into yarns was higher when the concentration is 50:50 wt%:wt% (1.2 mA). The cytotoxicity results showed a cell viability close to 100% for yarns without AA.