Collection efficiency of liquid‐based samplers for fungi in indoor air

This study assessed the collection efficiency (CE) of two popularly used sampling devices (BioSampler and Coriolis sampler) for fungal aerosols. Phosphate‐buffered saline (PBS) supplemented with or without surfactant (Tween‐20, Tween‐80, or Triton X‐100) and antifoam agent was prepared and used as collection liquids. The agar impactor (BioStage) was simultaneously operated with liquid‐based samplers to collect fungi from seven sites located at a university building, public library, and animal farming. Fungal concentrations determined by liquid samplers were divided by those by BioStage, and the ratio values represented CE. Results indicate that the CE of BioSampler was superior to that of Coriolis (P = 0.0001) and the PBS containing surfactant collected fungi better than that without surfactant (P < 0.0001), whereas antifoam agent showed no influence (P = 0.8). Moreover, fungal concentrations determined by BioSampler with surfactant‐added PBS were statistically indifferent from those by BioStage (P > 0.05) with a Spearman correlation coefficient of 0.81‐0.83 (P < 0.01). In addition to sampler and collection liquid, sampling location was also identified as a significant CE factor (P = 0.006), implying potential influences by fungal genera in the studied fields. Overall, BioSampler with surfactant‐supplemented PBS (eg, Triton X‐100) is recommended considering the great CE and compatibility with a variety of analytical assays.     

Sliding wear of Al2O3P/6061 Al composite

The mild sliding wear behaviour of a 15 vol % Al₂O_3P/6061 Al composite has been investigated by using a pin-on-disc reciprocating sliding machine. The composite has been shown to exhibit an excellent wear resistance as compared to the unreinforced matrix alloy. The wear rate of the composite under dry wear conditions with a 12N load is approximately one tenth of that in the 6061 aluminium alloy. The wear rate of the composite under lubrication with 15W/40 gear oil under a 100N load is only one thousandth ofthat in the 6061 aluminium alloy.The dry wear resistance of an over-aged sample is shown here to be better than a peak aged or under-aged sample when the composite was aged at 160°C. The coefficient of friction of the composite was approximately 0.5–0.6 under dry conditions and 0.07 in lubricated wear experiments.In the initial stage, the worn surface of the composite under dry conditions is primarily composed of ploughed grooves and ductile tear. The composite makes a conducting contact with the steel pin. The worn surface is composed of compacted powder and the contact potential gradually increases when the period of the wear experiment goes beyond 2 h.     

Efficiency improvement of near-ultraviolet InGaN LEDs using patterned sapphire substrates

The use of conventional and patterned sapphire substrates (PSSs) to fabricate InGaN-based near-ultraviolet (410 nm) light-emitting diodes (LEDs) was demonstrated. The PSS was prepared using a periodic hole pattern (diameter: 3 /spl mu/m; spacing: 3 /spl mu/m) on the (0001) sapphire with different etching depths. From transmission-electron-microscopy and etch-pit-density studies, the PSS with an optimum pattern depth (D/sub h/=1.5 /spl mu/m) was confirmed to be an efficient way to reduce the thread dislocations in the GaN microstructure. It was found that the output power increased from 8.6 to 10.4 mW, corresponding to about 29% increases in the external quantum efficiency. However, the internal quantum efficiency (@ 20 mA) was about 36% and 38% for the conventional and PSS LEDs, respectively. The achieved improvement of the output power is not only due to the improvement of the internal quantum efficiency upon decreasing the dislocation density, but also due to the enhancement of the extraction efficiency using the PSS. Finally, better long-time reliability of the PSS LED performance was observed.     

Enhanced output power of near-ultraviolet InGaN-GaN LEDs grown on patterned sapphire substrates

Near-ultraviolet nitride-based light-emitting diodes (LEDs) with peak emission wavelengths around 410 nm were fabricated onto c-face patterned sapphire substrates (PSS). It was found that the electroluminescence intensity of the PSS LED shown 63% larger than that of the conventional LED. For a typical lamp-form PSS LED operating at a forward current of 20 mA, the output power and external quantum efficiency were estimated to be 10.4 mW and 14.1%, respectively. The improvement in the light intensity could be attributed to the decrease of threading dislocations and the increase of light extraction efficiency in the horizontal direction using a PSS.     

Solving the bi-objective personnel assignment problem using particle swarm optimization

A particle swarm optimization (PSO) algorithm combined with the random-key (RK) encoding scheme (named as PSORK) for solving a bi-objective personnel assignment problem (BOPAP) is presented. The main contribution of this work is to improve the f₁_f₂ heuristic algorithm which was proposed by Huang et al. [3]. The objective of the f₁_f₂ heuristic algorithm is to get a satisfaction level (SL) value which is satisfied to the bi-objective values f₁, and f₂ for the personnel assignment problem. In this paper, PSORK algorithm searches the solution of BOPAP space thoroughly. The experimental results show that the solution quality of BOPAP based on the proposed method is far better than that of the f₁_f₂ heuristic algorithm.     

An adaptive watermarking scheme for e-government document images

This paper proposes an adaptive watermarking scheme for e-government document images. The adaptive scheme combines the discrete cosine transform (DCT) and the singular value decomposition (SVD) using luminance masking. As a core of masking model in the human visual system (HVS), luminance masking is implemented to improve noise sensitivity. Genetic algorithm (GA), subsequently, is employed for the optimization of the scaling factor of the masking. Involving a number of steps, the scheme proposed through this study begins by calculating the mask of the host image using luminance masking. It is then continued by transforming the mask on each area into all frequencies domain. The watermark image, following this, is embedded by modifying the singular values of DCT-transformed host image with singular values of mask coefficient of host image and the control parameter of DCT-transformed watermark image using Genetic Algorithm (GA). The use of both the singular values and the control parameter respectively, in this case, is not only to improve the sensitivity of the watermark performance but also to avoid the false positive problem. The watermark image, afterwards, is extracted from the distorted images. The experiment results show the improved adaptive performance of the proposed scheme is in resistant to several types of attacks in comparison with the previous schemes; the adaptive performance refers to the adaptive parameter of the luminance masking functioned to improve the performance or robustness of an image from any attacks.     

Aspectualization of code clones—an algorithmic approach

System Modularity has positive effects on software maintainability, reusability, and understandability. One factor that can affect system modularity is code tangling due to code clones. Code tangling can have serious cross-cutting effects on the source code and thereby affect maintainability and reusability of the code. In this research we have developed an algorithmic approach to convert code clones to aspects in order to improve modularity and aid maintainability. Firstly, we use an existing code-clone detection tool to identify code clones in a source code. Secondly, we design algorithms to convert the code clones into aspects and do aspect composition with the original source code. Thirdly, we implement a prototype based on the algorithms. Fourthly, we carry out a performance analysis on the aspects composed source code and our analysis shows that the aspect composed code performs as well as the original code and even better in terms of execution times.     

A flowchart‐based intelligent tutoring system for improving problem‐solving skills of novice programmers

Intelligent tutoring and personalization are considered as the two most important factors in the research of learning systems and environments. An effective tool that can be used to improve problem‐solving ability is an Intelligent Tutoring System which is capable of mimicking a human tutor's actions in implementing a one‐to‐one personalized and adaptive teaching. In this paper, a novel Flowchart‐based Intelligent Tutoring System (FITS) is proposed benefiting from Bayesian networks for the process of decision making so as to aid students in problem‐solving activities and learning computer programming. FITS not only takes full advantage of Bayesian networks, but also benefits from a multi‐agent system using an automatic text‐to‐flowchart conversion approach for engaging novice programmers in flowchart development with the aim of improving their problem‐solving skills. In the end, in order to investigate the efficacy of FITS in problem‐solving ability acquisition, a quasi‐experimental design was adopted by this research. According to the results, students in the FITS group experienced better improvement in their problem‐solving abilities than those in the control group. Moreover, with regard to the improvement of a user's problem‐solving ability, FITS has shown to be considerably effective for students with different levels of prior knowledge, especially for those with a lower level of prior knowledge.     

Simulation of solid thermal explosion and liquid thermal explosion of dicumyl peroxide using calorimetric technique

Dicumyl peroxide (DCPO), is produced by cumene hydroperoxide (CHP) process, is utilized as an initiator for polymerization, a prevailing source of free radicals, a hardener, and a linking agent. DCPO has caused several thermal explosion and runaway reaction accidents in reaction and storage zone in Taiwan because of its unstable reactive property. Differential scanning calorimetry (DSC) was used to determine thermokinetic parameters including 700 J g^–1 of heat of decomposition (ΔH_d), 110 °C of exothermic onset temperature (T₀), 130 kJ mol^–1 of activation energy (E_a), etc., and to analyze the runaway behavior of DCPO in a reaction and storage zone. To evaluate thermal explosion of DCPO with storage equipment, solid thermal explosion (STE) and liquid thermal explosion (LTE) of thermal safety software (TSS) were applied to simulate storage tank under various environmental temperatures (T_e). T_e exceeding the T₀ of DCPO can be discovered as a liquid thermal explosion situation. DCPO was stored under room temperature without sunshine and was prohibited exceeding 67 °C of self-accelerating decomposition temperature (SADT) for a tank (radius = 1 m and height = 2 m). SADT of DCPO in a box (width, length and height = 1 m, respectively) was determined to be 60 °C. The TSS was employed to simulate the fundamental thermal explosion behavior in a large tank or a drum. Results from curve fitting demonstrated that, even at the earlier stage of the reaction in the experiments, ambient temperature could elicit exothermic reactions of DCPO. To curtail the extent of the risk, relevant hazard information is quite significant and must be provided in the manufacturing process.     

MTPSO algorithm for solving planar graph coloring problem

In this paper, we proposed a modified turbulent particle swarm optimization (named MTPSO) model for solving planar graph coloring problem based on particle swarm optimization. The proposed model is consisting of the walking one strategy, assessment strategy and turbulent strategy. The proposed MTPSO model can solve the planar graph coloring problem using four-colors more efficiently and accurately. Compared to the results shown in Cui et al. (2008), not only the experimental results of the proposed model can get smaller average iterations but can get higher correction coloring rate when the number of nodes is greater than 30.