基于改进量子粒子群和主动PI模型的自适应无线传感器网络拥塞控制算法设计

针对无线传感器网络中路由节点需要转发大量数据导致网络拥塞,从而引起节点丢包率高和网络吞吐率过低的问题,提出了一种基于主动PI模型和改进量子粒子群优化算法的拥塞控制方法;首先定义了丢包率和队列长度计算方式;设计了改进的PI主动队列管理模型,然后,为了改进PI模型的控制效果,采用改进的量子粒子群算法对PI主动队列管理模型中的比例系数和积分系数kP和kI进行参数优化,从而得到能实现WSN自适应控制的主动PI控制模型;最后,对基于量子粒子群算法和PI主动队列模型的网络拥塞算法进行了描述和说明;仿真实验表明:文中提出的拥戴控制方法能有效实现WSN拥塞控制,是一种适用于WSN的有效拥塞控制方法,与其它方法相比,具有较短的平均队列长度和较大的网络吞吐率,具有很强的可行性。     

White-light-emitting diodes using GaN-excited CdSe/CdS/ZnS quantum dots

Fluorescence-based white-light-emitting diodes （WLEDs） were fabricated using blue GaN chips and green- and red-emitting CdSe/CdS/ZnS quantum dots （QDs）. The coordinate and color temperature of the WLEDs could be varied because of the size-tunable emission of CdSe QDs from 510 to 620 nm. Warm and cold white emissions were confirmed with the color temperature ranging from 4000 to 9000 K. Color coordinates were analyzed at different bias. The fast enhancement of blue emission resulted in the shift of color coordinates to the cold side. The stability of white emission during operation was analyzed; stable spectra were achieved within 90 min.     

Use of CT scans and treatment planning software for validation of the dose component of food irradiation protocols

The challenging problem of estimating the dose delivered to heterogeneous products by radiation modalities of limited penetration can be readily handled by using technologies developed for, and widely used in, radiation therapy applications. In particular, combining CT scanning with radiation treatment planning programs can simulate radiation processing with either photons or electrons, and can provide detailed, high resolution and accurate dose maps for any arbitrary product and package configuration. Such dose maps are an essential part of process validation. Comparison of the simulated dose distributions with measured dose maps verifies the soundness of this approach. The present communication presents results obtained with the simulation technique for a variety of common food items which are likely candidates for radiation processing.     

Batch gravitational sedimentation of slurries

We investigated the batch settling behavior of the kaolin slurry and the UK ball clay slurry at various initial solids fractions (phi(0)s) using a computerized axial tomography scanner (CATSCAN). The spatio-temporal evolutions of solids fractions in the consolidating sediments were continuously monitored. Since the interface between the sediment and the supernatant of the investigated slurries was blurred, an averaging procedure was employed to estimate their null-stress solids fractions (phi(g)s). Besides the rather slow settling for the high-phi(0) slurries, the basic settling characteristics resemble each other regardless of whether phi(0)>phi(g) or vice versa. The above-mentioned experimental data reveal that the investigated slurries are neither purely elastic nor purely plastic in rheological behavior. On contrary to most model works a blurred supernatant-sediment interface makes difficulty in the gel point determination. During initial settling the high-phi(0) slurries clearly exhibit a finite yield stress to resist deformation. That is, the slurries are plastic fluids. However, the network structure in the slurries deteriorates gradually in the subsequent settling stage while the final, equilibrated sediment reveals a continuous distribution in solids fraction. Restated, the final sediment possesses as a purely elastic characteristic. The model parameters of theory by Buscall and White were regressed by the dynamic consolidating sediment data, while those by Tiller and Leu were obtained using the final equilibrated sediment data. Calculations from both models reveal that ball clay slurry is more compressible than is the kaolin slurry. The high-phi(S0) slurry would yield the less compressible sediment.     

Outage probability analysis of FSO system with Airy beam as carrier

Optical Review - Based on the scintillation index of Airy beam and exponentiated Weibull channel model, analytical expressions of outage probability for free-space optical (FSO) communication links...     

Chemical composition, antioxidant and antimicrobial activity of the extracts of the flowers of the Chinese plant Chimonanthus praecox

This study investigated the antimicrobial and antioxidant activity of the extracts of the flowers, essential oil (EO) and semi-volatile fractions (SVF) of Chimonanthus praecox. The chemical composition of the EO was analysed by gas chromatography-mass spectroscopy (GC-MS) which revealed that the EO contained elemene, muurolene, caryophyllene, cadinol and spathulenol. The effective antibacterial activity of the EO suggested that its different responses on the microorganisms studied depended on the synergistic effects of the compounds contained in the EO. The effective antioxidant activity of the EO showed that the EO had a more marked antioxidant effect on scavenging O2(-)· and OH· than DPPH·, and SVF had a higher potential for scavenging DPPH· than the EO. Our data suggested that the flowers of Chimonanthus praecox had pharmaceutical benefits, and are also a potential source of natural antioxidants and biocides.     

Chemical composition and insecticidal activity of the essential oil of Amethystea caerulea L

The essential oil of the aerial parts of Amethystea caerulea L. was obtained from steam distillation and investigated by GC and GC-MS. The main components of the essential oil were morrilol (25.1%), 4-vinylguaiacol (14.3%) and acetoanisole (14.3%), followed by linalool (6.6%), eugenol (5.8%) and α-caryophyllene (5.2%). The essential oil showed pronounced contact toxicity against Drosophila melanogaster L. and maize weevil, Sitophilus zeamais (Motsch.), with LD(50) values of 5.18 and 50.45?μg per adult, respectively. The essential oil also possessed strong fumigant toxicity against the maize weevils with an LC(50) value of 25.39?μg?mL(-1).     

X-ray microscopy and tomography detect the accumulation of bare and PEG-coated gold nanoparticles in normal and tumor mouse tissues

We demonstrate that, with appropriate staining, high-resolution X-ray microscopy can image complicated tissue structures--cerebellum and liver--and resolve large or small amounts of Au nanoparticles in these tissues. Specifically, images of tumor tissue reveal high concentrations of accumulated Au nanoparticles. PEG (poly(ethylene glycol)) coating is quite effective in enhancing this accumulation and significantly modifies the mechanism of uptake by reticuloendothelial system (RES) organs.     

Preparation and synergetic catalytic effects of amino-functionalized MCM-41 catalysts

Four amine functionalized mesoporous catalysts were synthesized by grafting primary, dualistic and two secondary amines onto the channel walls of mesoporous silica, MCM-41. We examined the effects of organoamine loading amount on the acid-base synergism of the catalysts in the self-condensation reaction of n-butanal, a Knoevenagel condensation and a Henry reaction. We observed the balance of the amine and residual silanol amounts is crucial to the catalytic performances of the functionalized mesoporous catalysts. An optimum organoamine loading amount exists, which is dependent on the organoamine type. There is little difference in the optimum organoamine loading amount between different reactions. The secondary organoamine functionalized MCM-41 exhibits the best catalytic performance in the experimental range.