A fluid–structure interaction model of insect flight with flexible wings

We present a fluid–structure interactions (FSI) model of insect flapping flight with flexible wings. This FSI-based model is established by loosely coupling a finite element method (FEM)-based computational structural dynamic (CSD) model and a computational fluid dynamic (CFD)-based insect dynamic flight simulator. The CSD model is developed specifically for insect flapping flight, which is capable to model thin shell structures of insect flexible wings by taking into account the distribution and anisotropy in both wing morphology involving veins, membranes, fibers and density, and in wing material properties of Young’s modulus and Poisson’s ratios. The insect dynamic flight simulator that is based on a multi-block, overset grid, fortified Navier–Stokes solver is capable to integrate modeling of realistic wing-body morphology, realistic flapping-wing and body kinematics, and unsteady aerodynamics in flapping-wing flights. Validation of the FSI-based aerodynamics and structural dynamics in flexible wings is achieved through a set of benchmark tests and comparisons with measurements, which contain a heaving spanwise flexible wing, a heaving chordwise-flexible wing with a rigid teardrop element, and a realistic hawkmoth wing rotating in air. A FSI analysis of hawkmoth hovering with flapping flexible wings is then carried out and discussed with a specific focus on the in-flight deformation of the hawkmoth wings and hovering aerodynamic performances with the flexible and rigid wings. Our results demonstrate the feasibility of the present FSI model in accurately modeling and quantitatively evaluating flexible-wing aerodynamics of insect flapping flight in terms of the aerodynamic forces, the power consumption and the efficiency.     

Preparation of meander thin-film microsensor and investigation the influence of structural parameters on the giant magnetoimpedance effect

A novel GMI-based microsensor with symmetrical meander structure has been fabricated by MEMS technology and mutual perpendicularity between longitudinal external field and easy axis was established by electroplating process for reaching a higher GMI. The GMI effects of the 3 and 6 turns sample with different Cu line width has been investigated systematically. The longitudinal frequency dependence has been given and a new frequency characteristic was observed in this paper. The experimental results show the increasing of Cu line width in appropriate range and more turns can respectively lead to greater GMI effect, the positive GMI ratio peak in 6 turns sample is nearly 4.5 times over the 3 turns sample, the peak frequency is greatly increased with the increasing of turn number, and the GMI ratio in 3 and 6 turns sample both exhibits negative maximum value when H _L>50 Oe. In this work, the GMI ratio peak appears at f _AC=4.8 MHz in 6 turns sample with the Cu line width of 140 μm, almost reaches 183.7 % under H _L=17 Oe.     

The resource constrained project scheduling problem with multiple crashable modes: A heuristic procedure

We present a heuristic procedure for a nonpreemptive resource constrained project scheduling problem in which the duration/cost of an activity is determined by the mode selection and the duration reduction (crashing) applied within the selected mode. This problem is a natural combination of the time/cost trade-off problem and the resource constrained project scheduling problem. The objective is to determine each activity's start (finish) time, mode and duration so that the total project cost is minimized. Total project cost is the sum of all activity costs and the penalty cost for completing the project beyond its due date. We introduce a multi-pass algorithm. We report computational results with a set of 100 test problems and demonstrate the efficacy of the proposed heuristic procedure.     

Mathematic modelling of vapour compression refrigerating systems circuits for computer-aided functional design: A system approach

A system approach to mathematic modelling of vapour compression refrigerating system circuits for computer-aided functional design in its most common form is considered. Replacing circuits by graphs and replacing graphs by an incidence matrix is shown.     

Intersubband optical absorption of holes in quantum wells

The problem of hole energy spectrum and interlevel optical absorption in p -type quantum wells is considered theoretically. To obtain analytical results, terms in the Luttinger Hamiltonian containing in-plane momentum are treated as a perturbation. In this approximation energy spectrum, wave functions, hole statistics and interlevel optical matrix elements can be found for an arbitrary shape of quantum well. Finally, optical absorption spectra are calculated for different interlevel transitions.     

Spectroscopic diagnostics of a strongly inhomogeneous optically thick plasma. Part 1. The formation of asymmetric self-reversed emission and absorption lines: determination of electron impact half-width and electron concentration

An analysis has been carried out of the profiles of asymmetrically self-reversed emission lines and of absorption lines using various models for inhomogeneous optically thick plasmas. Conditions of impulsing discharge, exploding wires, sparks, plasma jets, laser ablation of a target, etc. were considered. The possibility of determining electron impact half-width and electron concentration from the wings of asymmetrically self-reversed lines is considered.     

Application of novel activated carbon fiber solid-phase, microextraction to the analysis of chlorinated hydrocarbons in water by gas chromatography-mass spectrometry

This paper presents a study on the performance of activated carbon fiber (ACF) used as extraction fiber for solid-phase microextraction (SPME) and its application for analysis of chlorinated hydrocarbons in water. By means of evaluating scanning electron microscope (SEM) images, specific surface area, pore volume, pore distribution, and properties of adsorption and desorption, the optimal active concentration of phosphoric acid has been determined. Coupled with gas chromatograph-mass spectrometry (GC-MS), ACF-SPME is suitable for determination chlorinated hydrocarbons in water with headspace. Experimental parameters such as adsorption and desorption conditions were studied. The optimized method has an acceptable linearity, good precision, with R.S.D. values <10% for each compound. Compared with commercial fibers, ACF has many advantages such as better resistance to organic solvents, better endurance to high temperature and longer lifetime.     

Asymmetric Construction of α,α-Disubstituted Piperazinones Enabled by Benzilic Amide Rearrangement

An unprecedent asymmetric catalytic benzilic amide rearrangement for the synthesis of α,α-disubstituted piperazinones is reported. The reaction proceeds via a domino [4+1] imidazolidination/formal 1,2-nitrogen shift/1,2-aryl or alkyl migration sequence, employing readily available vicinal tricarbonyl compounds and 1,2-diamines as starting materials. This approach provides an efficient access to chiral C3-disubsituted piperazin-2-ones with high enantiocontrol, which are exceedingly difficult to access from the existing synthetic methodologies. The observed enantioselectivity was proposed to be controlled by dynamic kinetic resolution in the 1,2-aryl/alkyl migration step. The resulting densely functionalized products are versatile building blocks to bioactive natural products, drug molecules and their analogues.     

Multiple approaches to characterize and visualize the chemical composition of Sijunzi Decoction comprehensively

Sijunzi Decoction is composed of Ginseng Radix et Rhizoma, Atractylodes Macrocephalae Rhizoma, Poria, and Glycyrrhizae Radix Et Rhizoma Praeparata Cum Melle, and it is a classic formula for treating spleen deficiency syndrome in Chinese medicine. Clarifying the active substances is an effective way to develop Traditional Chinese medicine and innovative medicines. Carbohydrates, proteins, amino acids, saponins, flavonoids, phenolic acids, and inorganic elements in the decoction were analyzed by multiple approaches. A molecular network was also used for visualizing the ingredients in Sijunzi Decoction, and representative components were also quantified. The detected components accounted for 74.544% of the Sijunzi Decoction freeze-dried powder, including 41.751% crude polysaccharides, 17.826% sugars (degree of polymerization 1–2), 8.181% total saponins, 2.427% insoluble precipitates, 2.154% free amino acids, 1.177% total flavonoids, 0.546% total phenolic acids, and 0.483% inorganic elements. Molecular network and quantitative analysis used to characterize the chemical composition of Sijunzi Decoction. The present study systematically characterized the constituents of Sijunzi Decoction, revealed the composition ratio of each type of constituent, and provided a reference for study on the substance basis of other Chinese medicine.     

Separation and determination of abused drugs clenbuterol and salbutamol from complex extractants in swine feed by capillary zone electrophoresis with simple pretreatment

A simple but efficient capillary zone electrophoresis (CZE) method was developed for the fast separation and determination of two misused beta2-agonists clenbuterol (CLB) and salbutamol (SAL) from complex background extractants existing in swine feed samples. The proper experimental conditions were achieved as 20.0 mmol/l pH 10.5 Na(2)HPO(4)-NaOH buffer, 20 kV applied voltage, fused-silica capillary of 60.5 cm x 75 microm i.d. (50 cm to detector). Under the proper conditions, the two abused drugs can be online isolated from the complex extractants and the separation between CLB and SAL is good, all of the target analytes can be detected within 4.5 min. The linear response of CLB and SAL concentration ranges from 2.0 to 100.0 microg/ml with high correlation coefficient (R(2)=0.9990) and (R(2)=0.9986), respectively. Limit of detection (LOD) and limit of quantification (LOQ) was calculated to be 0.95 and 3.17 microg/ml for CLB, 1.07 and 3.57 microg/ml for SAL. The precision values (expressed as R.S.D.) of intra- and inter-day were 1.24-2.36% and 0.90-3.85% for CLB, 0.47-1.64% and 0.91-3.46% for SAL. Recoveries spiked at levels 5.0, 25.0, 80.0 microg/ml ranged between 93.30% and 104.33% with R.S.D. less than 5%. Finally, the developed method has been applied to the analysis of real swine feed samples and has achieved satisfactory results.