Design and Operation of a Pressure-Controlled Inlet for Airborne Sampling with an Aerodynamic Aerosol Lens

Two pressure-controlled inlets (PCI) have been designed and integrated into the Aerodyne Aerosol Mass Spectrometer (AMS) inlet system containing an aerodynamic aerosol lens system for use in airborne measurements. Laboratory experiments show that size calibration and mass flow rate into the AMS are not affected by changes in upstream pressure (P ₀ ) of the PCI as long as the pressure within the PCI chamber (P _PCI ) is controlled to values lower than P ₀ . Numerous experiments were conducted at different P _PCI , P ₀ , and AMS lens pressures (P _Lens ) to determine particle transmission efficiency into the AMS. Based on the results, optimum operating conditions were selected which allow for constant pressure sampling with close to 100% transmission efficiency of particles in the size range of ～ 100–700 nm vacuum aerodynamic diameter (d _va ) at altitudes up to ～ 6.5 km. Data from an airborne field study are presented for illustration.     

A study of concept-based similarity approaches for recommending program examples

This paper investigates a range of concept-based example recommendation approaches that we developed to provide example-based problem-solving support in the domain of programming. The goal of these approaches is to offer students a set of most relevant remedial examples when they have trouble solving a code comprehension problem where students examine a program code to determine its output or the final value of a variable. In this paper, we use the ideas of semantic-level similarity-based linking developed in the area of intelligent hypertext to generate examples for the given problem. To determine the best-performing approach, we explored two groups of similarity approaches for selecting examples: non-structural approaches focusing on examples that are similar to the problem in terms of concept coverage and structural approaches focusing on examples that are similar to the problem by the structure of the content. We also explored the value of personalized example recommendation based on student's knowledge levels and learning goal of the exercise. The paper presents concept-based similarity approaches that we developed, explains the data collection studies and reports the result of comparative analysis. The results of our analysis showed better ranking performance of the personalized structural variant of cosine similarity approach.     

Study of Learning Fuzzy Controllers

This paper compares two types of learning fuzzy controllers, the self-organizing fuzzy (SOF) controller and the hybrid self-organizing fuzzy proportional–integral–derivative (SOF-PID) controller. The SOF is an extension of the rule-based fuzzy controller, with additional rule creation and rule modification mechanisms. The hybrid SOF-PID comprises the SOF as a learning supervisory controller readjusting the proportional gain of the PID controller at the actuator section, when the system is on line. The structures of the SOF controller and the hybrid SOF-PID controller are studied. The performances of the SOF controller and the hybrid SOF-PID controller are compared by applying them to a two-link non-linear revolute-joint robot arm. For the path tracking experiments, the hybrid SOF-PID controller followed the required path more closely and smoothly than the SOF controller. The results of the experiments for the SOF controller and the hybrid SOF-PID controller are also compared with those obtained with a conventional PID controller, using the same values supplied at the setpoint.     

A fuzzy approach to active usage parameter control in IEEE 802.11b wireless networks

Abstract: Usage parameter control (UPC) provides support for quality of service across heterogeneous networks. For the network operator UPC assists in limiting network usage through traffic shaping, to prevent unacceptable delay. Traditional methods to apply UPC involve the generic cell rate algorithm or ‘leaky bucket’ algorithm, now commonly implemented in asynchronous transmission mode networks. This paper proposes a novel form of UPC for 802.11b wireless networks. The method proposed measures the rate of individual network flows to actively manage link utilization using a fuzzy logic controller (FLC). The FLC monitors the flow rate and adjusts the sending transmissions to stabilize flows as close to the optimum desired rate as possible. Imposing UPC and using the FLC within a packet switched TCP network enforces cooperation between competing streams of traffic. After carrying out experiments within a wireless network, the results obtained significantly improve upon a ‘best effort’ service.     

Cationic metalloporphyrins for synthesis of conducting,water-soluble polyaniline

Catalytic oxidative polymerization of aniline was performed using the tetrapyridylporphyrin (TPyP) complexes of iron (III), manganese (III) and cobalt (III). It was found that the cationic metalloporphyrin catalyzed the polymerization of aniline more efficiently than the anionic metalloporphyrins, when using aqueous H₂O₂. The reaction was carried out in the presence of sulfonated polystyrene (SPS) as a template at different pHs, ranging from 1 to 5, and the best results were obtained at pH 2. Formation of water-soluble polyaniline (PANI) was characterized by UV–vis, FT-IR spectroscopy and cyclic voltammetry (CV). FT-IR and UV–vis spectra confirm the formation of the conducting form of PANI. Cyclic voltammetry measurements demonstrate that the polymer has convenient electroactivity.     

In situ synthesized chitosan–gelatin/ZnO nanocomposite scaffold with drug delivery properties: Higher antibacterial and lower cytotoxicity effects

In this work, chitosan–gelatin/zinc oxide nanocomposite hydrogel scaffolds (CS–GEL/nZnO) were prepared via in situ synthesis of ZnO nanoparticles (nZnO) to reach a scaffold with both inherent antibacterial and drug delivery properties. The prepared nanocomposite hydrogel scaffolds were characterized using scanning electron microscopy, transmission electron microscopy, atomic absorption spectrometer, Fourier transform infrared spectroscopy, and X-ray diffraction. In addition, swelling, biodegradation, antibacterial, cytocompatibility, and cell attachment of the scaffolds were evaluated. The results showed that the prepared scaffolds had high porosity with a pore size of 50–400 μm and nZnO were well distributed without any agglomeration on the CS–GEL matrix. In addition, the nanocomposite scaffolds showed enhanced swelling, biodegradation, and antibacterial properties. Moreover, the drug delivery studies using naproxen showed that nZnO could control naproxen release. Cytocompatibility of the samples was proved using normal human dermal fibroblast cells (HFF2). In comparison to the previous reports which nZnO were simply added to the matrix of the scaffold, in situ synthesis of nZnO was led to higher antibacterial and lower cytotoxicity effects as a result of well distribution of nZnO in this method. According to the findings, the in situ synthesized CS–GEL/nZnO is strongly recommended for biomedical applications especially skin tissue engineering. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47590.     

Conversion of high silicon fly ash to Na-P1 zeolite: Alkaline fusion followed by hydrothermal crystallization

In this research, we converted high silicon fly ash to a high ion-exchange capacity zeolite using a two stages conversion process. Alkaline fusion was applied to collapse the fly ash crystalline phases and release Si content. Then Si/Al ratio of the synthesis sol adjusted with appropriate amount of industrial grade materials. A synthesis solution with the molar ratio of 2.2 SiO₂:Al₂O₃:5.28 Na₂O:106 H₂O was hydrothermally crystallized to Na-P1 zeolite at 120 °C for 4 h. The as-synthesized zeolite characterized by means of X-ray diffraction, infrared spectroscopy, scanning electron microscopy and thermal analysis. Cation exchange capacity of the zeolite was determined using ammonium acetate method. The zeolitization remarkably improved the cation exchange capacity of the final product (e.g. 3.23 meq/g in comparison to the raw fly ash ～0.005–0.02 meq/g).Due to the high CEC and sufficient whiteness of the final product, we suggest that the as-synthesized zeolitic powder is a potential candidate as a detergent builder.     

Comparative study of a learning fuzzy PID controller and a self-tuning controller

The self-organising fuzzy controller is an extension of the rule-based fuzzy controller with an additional learning capability. The self-organising fuzzy (SOF) is used as a master controller to readjust conventional PID gains at the actuator level during the system operation, copying the experience of a human operator. The application of the self-organising fuzzy PID (SOF-PID) controller to a 2-link non-linear revolute-joint robot-arm is studied using path tracking trajectories at the setpoint. For the purpose of comparison, the same experiments are repeated by using the self-tuning controller subject to the same data supplied at the setpoint. For the path tracking experiments, the output trajectories of the SOF-PID controller followed the specified path closer and smoother than the self-tuning controller.     

Synthesis,characterization, and drug‐release behavior of novel PEGylated bovine serum albumin as a carrier for anticancer agents

To develop a novel pH‐sensitive PEGylated carrier for protein‐based anticancer agents, we modified bovine serum albumin (BSA) with poly(ethylene glycol) citrate ester (PEG–CA) through amidation with its amino groups. Increasing the mixing ratio of albumin from 3 to 6 with respect to PEG–CA resulted in a 2‐fold increase in the degree of albumin modification. Adriamycin (ADR)‐loaded PEG–CA–BSA hydrogels and microparticles were prepared, and the cumulative amounts of ADR released from the PEG–CA–BSA hydrogels (phosphate‐buffered saline, pH 7.4) showed that all the PEG‐CA‐BSA_(x) (x represents degree of substitution of PEG to amino group of albumin, i.e. 26%, 28%, 31% and 49%) hydrogels had lower ADR release rates with a slight initial burst release. During the first 24 h, the cumulative releases were 15.5% for PEG–CA–BSA₍₄₉₎, 24% for PEG–CA–BSA₍₃₁₎, 31% for PEG–CA–BSA₍₂₈₎, and 38% for PEG–CA–BSA₍₂₆₎. Afterward, all the release rates slowed, and they were almost in the following order: PEG–CA–BSA₍₂₆₎ > PEG–CA–BSA₍₂₈₎ > PEG–CA–BSA₍₃₁₎ > PEG–CA–BSA₍₄₉₎. The release rates of ADR from the microparticles were dependent on the amount of glutaraldehyde. According to our findings, a higher PEG–CA/BSA molar ratio led to a reduced cumulative amount of ADR released from the hydrogels, whereas higher release rates were observed for microparticles with a lower amount of BSA in the conjugates in a pH‐dependent manner. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011