Time-spreading wavelength-hopping optical CDMA system using EWO and TCM

In this paper, time-spreading wavelength-hopping optical CDMA system using trellis coded modulation scheme is investigated. The carrier hopping prime code and its shifted version are employed as signature sequences. Since the carrier hopping prime code is a symmetric code, the out of phase autocorrelation is zero. Applying the orthogonality of the signature sequences, the ternary transmission mechanism can be achieved. The proposed coding scheme is simple in both transmitter and receiver. As the multiple access interference and beat noise are the major deterioration of system performance, using coding scheme is an effective way to reduce the error floor. The numerical results reveal that the proposed coding scheme can significantly improve the system performance.     

Effect of heating temperature on the sintering characteristics of sewage sludge ash

This study investigated and analyzed the effects of the heating temperature on the properties of the sintered sewage sludge ash. The results indicated that the water absorption rate of the sintered sewage sludge ash samples decreased when the firing temperature was increased from 800 to 900 degrees C. When the heating temperature reached 1000 degrees C, the absorption rate decreased significantly. The bulk density of the sewage sludge ash samples increased by 2.3g/cm3 when the heating temperature was increased from 900 to 1000 degrees C, indicating that the densification was affected by heating. The porosity of the sintered sewage sludge ash samples ranged from 36% to 39% when the heating temperature ranged from 600 to 900 degrees C. The least porosity occurred at 1000 degrees C; the sintered samples were well densified. When the temperature was between 900 and 1000 degrees C, the strength appeared to increase significantly, reaching 2040 kgf/cm2, implying an advance in densification due to sintering. The SEM observations were in general agreement with the trends shown by the density data.     

Degradation of di-n-butyl phthalate using photoreactor packed with TiO2 immobilized on glass beads

This study evaluated the performance of a photoreactor packed with TiO2/glass, TiO2 immobilized on glass beads, initiated by UV irradiation, denoted as UV/TiO2/glass, to decompose di-n-butyl phthalate (DBP) in an aqueous solution. The photodegradation rate of DBP by this UV/TiO2/glass process was found to obey pseudo first-order kinetics represented by the Langmuir-Hinshelwood model. The experimental results of this study show that the influence of pH value of an aqueous solution to reaction rate was negligible at the pH values 4.5-9. The effect of cations on the photodegradation rate of DBP reveals that the larger the charge and size of cations contained, the more the inhibition of reaction rate increased. The UV/TiO2/glass process yielded a 75% degradation efficiency of DBP with initial concentration of 5 mg L(-1) at 80 min reaction time.     

Feasibility study of using brick made from municipal solid waste incinerator fly ash slag

This study deals with the effect of MSWI slag on fired clay bricks. Brick samples were heated to temperatures which varied from 800 to 1,000 degrees C for 6h, with a heating rate of 10 degrees C/min. The material properties of the resultant material then determined, including speciation variation, loss on ignition, shrinkage, bulk density, 24-h absorption rate and compressive strength. Toxicity Characteristic Leaching Procedure tests were also conducted. The results indicate that the heavy metal concentrations in the leachates met the current regulatory thresholds. Increasing the amount of MSWI slag resulted in a decrease in the water absorption rate and an increase in the compressive strength of the MSWI-slag bricks. The 24-h absorption rate and compressive strength of the MSWI-slag brick made from samples containing slag sintered at 1,000 degrees C all met the Chinese National Standard (CNS) building requirements for second-class brick. The addition of MSWI slag to the mixture reduced the degree of firing shrinkage. This indicates that MSWI slag is indeed suitable for the partial replacement of clay in bricks.     

AgMgAl metallic glassy and intermetallic thin films for electric contact applications

The AgMgAl thin films, in an attempt in replacing the expensive pure Au contact films, are prepared by co-sputtering. The surface morphology, roughness, amorphous or crystalline atomic structure, grain size, and electric resistivity are systematically examined. Depending on the film compositions, the films can be fully amorphous or fully nanocrystalline, or a composite with the mixture of nanocrystalline phases dispersed in the amorphous matrix. Under the as-sputtered condition, the crystalline group has the lowest resistivity, ranging from 27 to 37 μΩ·cm, the composite group lies in the middle, 31–70 μΩ·cm, and the fully amorphous group possesses the highest resistivity, 87–122 μΩ·cm. Appropriate short thermal annealing for the amorphous films can drastically lower the resistivity down to as low as 9 μΩ·cm, already compatible to pure Au (3–7 μΩ·cm). This study demonstrates the feasibility of the AgMgAl films in replacing the pure Au.     

Effect of electrode spacing on the performance of microbial fuel cells with a honeycomb flow straightener

Microbial fuel cells (MFCs) are bioelectrochemical transducers that can be used to produce electrical power under the activity of microbes during the wastewater treatment processes. In the present study, the electrode spacing was considered as a parameter to investigate the influence on the performance of MFCs. The electrode spacing was defined as the distance of the anode electrode plate to the polymer exchange membrane in the MFCs. Three values were set at 0.0, 3.0, and 6.0 cm, respectively. In addition, a flow device, like a honeycomb type flow straightener, was introduced and implemented in the anode chamber for creating a uniform flow. The inner diameter of the honeycomb was 0.7 cm. Results showed that a higher limiting current density with 4108.7 mA/m² and a lower resistance with 2.51 Ω can be found in the case of the 0.0 cm electrode spacing. These results also indicated that the shorter electrode spacing with flow straightener devices would improve the performance of MFCs, leading to lower internal resistance and higher power density. In addition, the scanning electron microscopy was employed to analyze the biofilm thickness for MFCs with different electrode spacing. It was also found that the biofilm thickness with 0 cm electrode spacing was larger than the other two cases, leading to a lower internal resistance in the MFCs.     

Prediction of the cutting temperatures of stainless steel with chamfered main cutting edge tools

The main purpose of this report is to predict the temperature of carbide tip's surface and study the cutting forces of turning stainless steel with sharp chamfered main cutting tools. The friction forces and frictional heat generated on elementary cutting tools are calculated by using the measured cutting forces and the oblique cutting analysis. The heat partition factors between the tip and chip are solved by using the inverse heat transfer analysis, which utilizes temperature on the carbide tip's surface measured by infrared as the input. The temperature of the carbide tip's surface is solved by finite element analysis (FEA) and compared with those obtained from experimental measurements. A good agreement demonstrates the accuracy of the proposed model.     

Investigation on the polyamide 6/organoclay nanocomposites with or without a maleated polyolefin elastomer as a toughener

Polyamide 6 (PA 6)-based nanocomposites were prepared using a melt-mixing technique in this study. One commercial organoclay (denoted 30B) and one maleated polyolefin elastomer (denoted POEMA) served as the reinforcing filler and toughener, respectively. The X-ray diffraction (XRD), scanning electron microscopy combined with energy dispersive spectroscopy (SEM/EDS) and transmission electron microscopy (TEM) results confirmed the nano-scaled dispersion of 30B in the composites. Different mixing sequences presented similar phase morphology for the same formulated nanocomposites. XRD results also revealed that both 30B and POEMA would induce the formation of γ form PA 6 crystal, with 30B exhibiting a higher efficiency. Differential scanning calorimetry (DSC) results indicated that the addition of 30B altered the crystallization kinetics of PA 6, which was mainly attributed to the prevailing formation of γ form crystal. Complex melting behaviors were observed for neat PA 6 and the nanocomposites. These complex behaviors are associated with different polymorphs and the ‘melting-recrystallization-remelting’ phenomenon. Moderate thermal stability enhancement of PA 6 after adding 30B and/or POEMA was confirmed using thermogravimetric analysis (TGA). The storage modulus, Young's modulus and tensile strength of PA 6 were increased after adding 30B. However, these properties declined after further incorporation of POEMA. The different-processed PA 6/30B/POEMA nanocomposites displayed balanced tensile properties and toughness between those of neat PA 6 and PA 6/30B nanocomposite.     

Backup routing firewall mechanism in P2P environment

This paper will discuss the most important source in the peer-to-peer networking. The backup routing mechanism is used in the peer-to-peer networking to avoid the discontinue downloading file. Each node uses the single nose and the single connection as the downloading source in the peer-to-peer networking in current model. Any source disconnected would be replaced by others when there are multiple sources for requirement. One loses the connection and fails the downloading files one need. The new backup routing would improve the above condition.     

Miscibility and toughness improvement of poly(lactic acid)/poly(3-Hydroxybutyrate) blends using a melt-induced degradation approach

Biodegradable polymer blends of high-molecular-weight poly(3-hydroxybutyrate) (PHB) and poly(lactic acid) (PLA) are not miscible in general. Yet, by decreasing the molecular weight of PHB, the low-molecular-weight PHB could have improved miscibility with the PLA. In this study, a melt-induced degradation process of PLA/PHB blends was therefore implemented, termed the in-situ self-compatibilization approach, to produce low-molecular-weight PHB during melt blending process. The solution blends of PLA and oligomer PHB (PLA/OPHB) were also prepared as a basis to understand the role of low-molecular-weight PHB to improve its miscibility with PLA in PLA/PHB blends. Only one single glass transition temperature (T_g) was found for the resulting PLA/PHB blends at compositions of 95/05 to 80/20, proving that the miscibility was greatly improved by decreasing molecular weight of PHB. Because the degraded PHB had a relatively lower T_g, it thus provided plasticization effect to the PLA and resulted in the decreased crystallization temperature. Moreover, with increasing PHB content to 20% in the blend, the elongation at break increased significantly from 7.2% to 227%, more than 30-fold. The extensive shear yielding and necking behavior were observed during tensile testing for the blend of 80/20. The localized plasticization within PLA/PHB matrix with the reduction of local yield stress and the well-dispersed PHB crystallites were the major contributing factors to trigger shear yielding phenomenon. Moreover, initial modulus decreased only 20%, from 1.68 to 1.35 GPa. A common problem of severely reduced stiffness from the added plasticizer encountered in the plasticized PLA blends was therefore not perceived here.