Adaptive crosshatch approach for the laminated object manufacturing (LOM) process

The waste material removal process of laminated object manufacturing (LOM), so-called 'decubing', is a labour-intensive and time-consuming work resulting from the commonly used uniform crosshatch setting. An adaptive crosshatch approach to improve working efficiency and alleviate the effort involved in the decubing process is developed. The working region is divided into two portions, the inner region and the outer region, by the proposed rectangle and original contour offset approaches. The fine crosshatch pattern is designated to the inner region based on the shape of the cross-section contour, and the rules to select crosshatches for different shapes are given. The outer region has a coarse crosshatch pattern, and it is an integer multiple of that of the inner region. The brick-layered effect in the overlap zone of the waste material is eliminated by the projection method. Experiments show that with the adaptive crosshatch approach there are four major advantages: saving laser power consumption, protecting the part from damage, improving machining efficiency and easier decubing.     

Adaptive autopilot design via model expansion method

Abstract

The concept of an equivalent time constant and model expansion method are introduced for the design of a synthetic stabilization acceleration autopilot. In the autopilot control loop, an extended Kalman filter is employed to estimate the time‐varying airframe parameters. The performance of the autopilot and the extended Kalman filter is investigated through computer simulations. Two main results are found: the model expansion method can efficiently specify the gains of the autopilot control loop, and good command following characteristics of the autopilot have been obtained in the computer simulations. The results also show an acceptable estimation error for the extended Kalman filter.     

Synthesis of porous micro-sized titania cages and their photocatalytic property

Micro-sized TiO₂ cage consisted of anatase nanoparticles on the edges of each cube, was synthesized using TTIP as the reagent and NaF submicrometer sized cubes as the template. When a salt of cube was adopted as the template, the reactants prefer to grow on the active sites, edges and corners of the cube, after removing the NaF template, the skeleton of the cube remain as the cage-shaped materials. The hierarchical structures with nano-sized anatase particles and micro scaled cage architecture markedly enlarge the surface area and enhance the light harvesting by light scattering of TiO₂ frame, resulting in great photo-catalytic performance, which leads to the photo-degradation of methylene blue by 40% higher than that was achieved by crushed nanoparticles.     

A decreasing inertia weight particle swarm optimizer

It has been over ten years since the pioneering work of particle swarm optimization (PSO) espoused by Kennedy and Eberhart. Since then, various modifications, well suited to particular application areas, have been reported widely in the literature. The evolutionary concept of PSO is clear-cut in nature, easy to implement in practice, and computationally efficient in comparison to other evolutionary algorithms. The above-mentioned merits are primarily the motivation of this article to investigate PSO when applied to continuous optimization problems. The performance of conventional PSO on the solution quality and convergence speed deteriorates when the function to be optimized is multimodal or with a large problem size. Toward that end, it is of great practical value to develop a modified particle swarm optimizer suitable for solving high-dimensional, multimodal optimization problems. In the first part of the article, the design of experiments (DOE) has been conducted comprehensively to examine the influences of each parameter in PSO. Based upon the DOE results, a modified PSO algorithm, termed Decreasing-Weight Particle Swarm Optimization (DW-PSO), is addressed. Two performance measures, the success rate and number of function evaluations, are used to evaluate the proposed method. The computational comparisons with the existing PSO algorithms show that DW-PSO exhibits a noticeable advantage, especially when it is performed to solve high-dimensional problems.     

In Situ ESEM Examination of Microstructural Changes of an Apple Tissue Sample Undergoing Low-Pressure Air-Drying Followed by Wetting

Low-pressure drying of apple tissue has been visualized in situ using an environmental scanning electron microscope (ESEM). Both freshly cut and pre-boiled sample tissues were tested for drying and followed by wetting processes and the differences between the two types of samples noted. Bubble formation was observed when drying the freshly cut sample and were found to form only around the intact cells (intracellular spaces or channels). Boiling produced a more uniform surface and no bubble formation could be observed. Air-drying of the two tissue samples was conducted as a complementary investigation so that the effect of boiling can be better ascertained.     

A coupled-inductor dual-mode switched voltage-controlled oscillator using GaN-on-Si HEMT technology

A coupled-inductors dual-mode switch cross-coupled pair voltage-controlled oscillator (VCO) was presented, adopting GaN-on-Si high-electron-mobility transistor technology. The coupled inductors create two resonant frequencies that cover a wide frequency range. The two continuous bands were achieved by using coupled inductors, and the fine-tuning is controlled by varactors. The low and high bands of the VCO were 2.77–3.11 GHz and 3–3.28 GHz, in the V_c range between 10 and 17 V, respectively, which corresponds to a 16.7% (510 MHz) tuning range. The lowest phase noise was ?123 dBc/Hz at an offset frequency of 1 MHz, and the highest output power was 17.7 dBm using a 7.5-V power supply.     

Comparison of Dynamic Differential Evolution and Genetic Algorithm for MIMO-WLAN Transmitter Antenna Location in Indoor Environment

A novel optimization procedure for the location of the transmitter in $3\times 3$ multiple input multiple output (MIMO) wireless local area network (WLAN) wireless communication systems is presented. The optimal antenna location for maximizing the channel capacity is searched by dynamic differential evolution (DDE) and genetic algorithm (GA). There are two different receiver locations considered in the simulation. The receivers are located with uniform intervals distribution either on the tables or in the whole indoor environment. Numerical results show that the performance for increasing channel capacity by DDE algorithm is better than that by GA.     

Biological properties of acidic cosmetic water from seawater

This current work was to investigate the biological effects of acidic cosmetic water (ACW) on various biological assays. ACW was isolated from seawater and demonstrated several bio-functions at various concentration ranges. ACW showed a satisfactory effect against Staphylococcus aureus, which reduced 90% of bacterial growth after a 5-second exposure. We used cultured human peripheral blood mononuclear cells (PBMCs) to test the properties of ACW in inflammatory cytokine release, and it did not induce inflammatory cytokine release from un-stimulated, normal PBMCs. However, ACW was able to inhibit bacterial lipopolysaccharide (LPS)-induced inflammatory cytokine TNF-α released from PBMCs, showing an anti-inflammation potential. Furthermore, ACW did not stimulate the rat basophilic leukemia cell (RBL-2H3) related allergy response on de-granulation. Our data presented ACW with a strong anti-oxidative ability in a superoxide anion radical scavenging assay. In mass spectrometry information, magnesium and zinc ions demonstrated bio-functional detections for anti-inflammation as well as other metal ions such as potassium and calcium were observed. ACW also had minor tyrosinase and melanin decreasing activities in human epidermal melanocytes (HEMn-MP) without apparent cytotoxicity. In addition, the cell proliferation assay illustrated anti-growth and anti-migration effects of ACW on human skin melanoma cells (A375.S2) indicating that it exerted the anti-cancer potential against skin cancer. The results obtained from biological assays showed that ACW possessed multiple bioactivities, including anti-microorganism, anti-inflammation, allergy-free, antioxidant, anti-melanin and anticancer properties. To our knowledge, this was the first report presenting these bioactivities on ACW.     

Reliability characteristics and conduction mechanisms in resistive switching memory devices using ZnO thin films

ABSTRACT: In this work, bipolar resistive switching characteristics were demonstrated in the Pt/ZnO/Pt structure. Reliability tests show that ac cycling endurance level above 106 can be achieved. However, significant window closure takes place after about 102 dc cycles. Data retention characteristic exhibits no observed degradation after 168 h. Read durability shows stable resistance states after 106 read times. The current transportation in ZnO films is dominated by the hopping conduction and the ohmic conduction in high-resistance and low-resistance states, respectively. Therefore, the electrical parameters of trap energy level, trap spacing, Fermi level, electron mobility, and effective density of states in conduction band in ZnO were identified.