Optimal deployment strategy of airships for near-space communication system using multiobjective advanced evolutionary algorithm

This paper presents a near-space communication system (NSCS) using advanced deployment strategies to gain high throughput. The airships are deployed according to the user's location, assuming robust backbone network characteristics such as signal path loss, fading factor, routing efficiency, and safety issues among bi-connected airships. Due to the independent flying nature of airships, it is very attractive to deploy them as aerial base stations and construct airborne networks to provide service for on-ground users. However, it is quite challenging to optimally deploy multiple airships for on-demand coverage while maintaining the connectivity among airships. A balance between the network parameters, i.e., capacity and coverage area, should be maintained for optimal deployment of the airships. We have derived the maximum throughput of NSCS, including system parameters, as a multiobjective optimization problem subjected to efficient routing protocol and safety constraints. A decomposition-based advanced multiobjective evolutionary algorithm (AMOEA/D) is adopted to solve the deployment optimization problem. The proposed algorithm is motivated by the non-dominated solutions that maintain population diversity over the variable space. Two designed test problems, that is, the L-shaped hotspot problem and nine hotspot problems, are also investigated. Numerical results show that the proposed method improves the system performance compared with benchmark external archive-guided MOEA/D (EGA-MOEA/D) and non-dominated sorted genetic algorithms (NSGA-II) by 10.46% and 3.84%, respectively.     

Automated Process Planning for the Manufacture of Lifters

This paper presents the methodology of a computer-aided process planning system IMOLD  FCAPP for the manufacture of injection moulded components, which will facilitate the standardisation of process planning and significantly reduce lead-time. The main components of the mould such as the slider, the lifter and the mould base are considered in this system. In this paper, the automated process planning for the manufacture of a lifter is described. A combination of the generative and variant approach (hybrid approach) is used for the development of the system. The input to the system is a 3D lifter model. First, the system classifies the lifter types and extracts the feature parameters from the model. Each lifter type refers to a standard process plan template, in which a set of processes is presented in sequence. Secondly, the system selects the machines, cutters, fixtures, and cutting parameters for each process in the plan template, based on the actual dimensions of the features and constraints and rules defined in the system and the available machining resources. The process plan execution is then simulated on the screen step by step.     

Simulation of semiconductor quantum well lasers

A new quantum well laser simulator that accounts for details of carrier transport, distribution of two-dimensional (2-D) carriers within the quantum well, optical gain spectra, and photon rate equations, is presented. The resulting set of complicated equations is solved using “slack variables”-a new algorithm that is both efficient and stable. Results are compared with experiments to verify the simulator     

Optimization of bending and shear rigidities of woven fabrics using desirability function

Abstract

Banding and shear properties influence the drape and handle characteristics of woven fabrics. As bending and shear rigidities of woven fabrics generally have high degree of association, it is difficult to design a woven fabric having low bending rigidity and high shear rigidity or vice versa. This paper deals with the optimization of bending and shear rigidities of woven fabrics using the desirability function approach. Low stress mechanical properties such as bending rigidity and shear rigidity have been combined to represent ‘the overall desirability’ which is varying from 0 to 1. The overall desirability has been maximized against the target values of shear and bending rigidities. It was possible to attain overall desirability of 0.684 resulting from individual desirability of 0.662 and 0.707 for banding and shear rigidities, respectively. Experimental validation confirms that the applied method can be effectively used to optimize the woven fabric mechanical properties at low stress region.     

8- and 16-channel all-fiber DFB laser WDM transmitters withintegrated pump redundancy

All-fiber DFB-laser-based 8-channel 100-GHz and 16-channel 50-GHz wavelength-division-multiplexing (WDM) transmitter arrays with integrated pump redundancy are demonstrated for the first time. Each fiber laser WDM channel in the modules remain in operation despite the drop out of several of the pump diodes and the maximum power drop to each channel in an 8×8 channel 100-GHz system for the drop of seven out of eight pump diodes is just 14 dB     

A field study evaluation for mitigating biofouling with chlorine dioxide or chlorine integrated with UV disinfection

The drinking water industry is continually seeking innovative disinfection strategies to control biofouling in transmission systems. This research, conducted in collaboration with the East Bay Municipal Utility District (EBMUD) in California, compared the efficacy of chlorine dioxide (ClO2) to free chlorine (Cl2) with and without pre-treatment with low-pressure ultraviolet (UV) light for biofilm control. An additional goal was to determine disinfection by-product (DBP) formation with each disinfection strategy. Annular reactors (ARs) containing polycarbonate coupons were used to simulate EBMUD's 90-mile aqueduct that transports surface water from a source reservoir to treatment facilities. ARs were dosed with chemical disinfectants to achieve a residual of 0.2 mg/L, which is a typical value mid-way in the aqueduct. The experiment matrix included four strategies of disinfection including UV/ClO2, ClO2, UV/Cl2 and Cl2. Two ARs acted as controls and received raw water (RW) or UV-treated water. The data presented show that the UV/ClO2 combination was most effective against suspended and attached heterotrophic (heterotrophic plate count, HPC) bacteria with 3.93 log and 2.05 log reductions, respectively. ClO2 was more effective than Cl2 at removing suspended HPC bacteria and similarly effective in biofilm bacterial removal. UV light alone was not effective in controlling suspended or biofilm bacteria compared to treatment with ClO2 or Cl2. Pre-treatment with UV was more effective overall for removal of HPC bacteria than treating with corresponding chemical disinfectants only; however, it did not lower required chemical dosages. Therefore, no significant differences were observed in DBP concentrations between ARs pre-treated with UV light and ARs not pre-treated. Disinfection with ClO2 produced fewer total trihalomethanes (TTHMs) and haloacetic acids (HAAs) than chlorination but did produce low levels of chlorite. These data indicate that replacing Cl2 with ClO2 would further control microbiological re-growth and minimize TTHM and HAA formation, but may introduce other DBPs.     

Binary Blends of Polytetrafluoroethylene and Liquid Crystalline Polymer

Blends of polytetrafluoroethylene (PTFE) and liquid crystalline polymer (LCP) were prepared by varying the amount of LCP when using a melt mixing technique. The rheological, morphological, thermal, and dynamic mechanical properties of the blends were investigated. The viscosity of the blends was decreased with the increasing LCP content in the blends up to 20% of LCP. With further loadings of LCP a slight improvement in viscosity was observed. This decrease in the viscosity was attributed to be the interlayer slip of the polymers due to formation of the elongated fibrils of LCP, whereas at higher amounts of LCP the fibril nature of LCP was not apparent, which is revealed by the scanning electron microscopic study. The differential scanning calorimetry (DSC) results showed a shift in the melting temperature (T_m) of PTFE with the addition of LCP. This shift in the T_m of PTFE is due to increasing crystallinity. This is further supported by the X-ray diffraction (XRD) and dynamic mechanical analysis (DMA) studies.     

Pro-Oxidant Effects of β-Carotene During Thermal Oxidation of Edible Oils

β-Carotene is one of the most important fat soluble pigments with well-known antioxidant and pro-vitamin A activity. It is used in industries as a food colorant and a source of vitamin A. The thermal induced degradation during processing of wide varieties of carotenoid-rich foods leads to color and properties losses. The thermal stability of edible oils is thus of great importance to food manufacturers. Corn oil, rapeseed, and sunflower oils were fortified with 50–300 μg/g of β-carotene and oxidized using a Rancimat apparatus (air flow rate 20 L/h) at 110 °C for 14 h. β-Carotene degradation was measured using high performance thin layer chromatography and confirmed by HPLC–DAD–MS. Triacylglycerols and polar compounds (PC) were determined using LC–ESI–MS. Results showed that most of the β-carotene was degraded during the first 5 h of the thermal oxidation. It was found that the addition of β-carotene produces significant effects (P < 0.05) on the peroxide index, free fatty acid values and radical scavenging activity of the three oils. Triacylglycerols containing high amounts of oleic acid show higher stability toward thermal oxidation and β-carotene treatment. Among the oils, rapeseed oil was the most stable oil in terms of the formation of polar compounds (PC), followed by corn oil, while sunflower oil was more prone to oxidation and thus higher amounts of PC were formed.     

Rearrangements of sp/sp hybridized bonding with phosphorus incorporation in pulsed laser deposited semiconducting carbon films by X-ray photoelectron spectroscopic analysis

The carbon films were grown on p-type silicon substrate at room temperature by pulsed (XeCl) laser deposition technique using camphoric carbon target containing 1%, 3%, 5% and 7% of phosphorus (P) by mass. The analysis of X-ray photoelectron spectroscopy spectra of the C1s region in these films shows the presence of sp² and sp³ hybridized carbon and a sp² satellite peak due to π–π shake up. The sp² content is seen to remain almost constant with P content. The FWHM of the sp² peak increases up to 5% P but decreases for 7% P probably due to clustering of sp² chains and this clustering in the sp² phase probably decreases the band gap for the 7% P film. With P incorporation, the tetrahedral bonding configurations of the carbon network do not change appreciably, therefore, suggesting the scope of phosphorus as a potential dopant in carbon films.