A biophysically based and objective satellite seasonality observation method for applications over the Arctic

Despite wide applications of remote-sensing data with high temporal resolution for monitoring phenology, two persistent problems have prevented the realization of their full potential. The first is the subjectivity in defining thresholds for a phenological event (e.g. the start or end of growing season ? SOS or EOS). The second is the use of various arbitrarily selected filtering and smoothing algorithms for constructing vegetation index seasonal profiles in order to reduce the noise caused by residue cloud contamination and aerosol variations. In this study, we addressed both problems by developing a biophysically based and objective satellite seasonality observation method (BLOSSOM) for application over Canada’s Arctic. Application of the BLOSSOM method to three northern Canadian national parks (Ivvavik, Wapusk, and Sirmilik) proved that the method is operational. Using the uncertainties in the vegetation index and its threshold, we estimated the overall mean uncertainties as being ?5.3 to 3.4 days, ?4.2 to 5.2 days, and ?6.2 to 8.4 days, respectively, for SOS, EOS, and growing season length (GSL). Further independent tests against SOS, determined using records of snow cover at nearby climate stations (as ‘truth’), indicate that the mean absolute error is less than 3.6 ± 0.2 days.     

Multiple thermosetting of semicrystalline polymers: Polyamide 66 and poly(ethylene terephthalate) fibers

Polyamide 66 fibers were thermoset in a torsion-bending deformation at various temperatures up to 240 °C. Some of the fibers were heat-set at constant length prior to the deformation at presetting temperatures of 150 °C and 200 °C to vary the structural state of the starting material. Fractional recovery was measured after various combinations of temperature and time. It was found that heat setting of PA66 is dominated by time-dependent stress relaxation exhibiting time-temperature equivalence. Increased crystallinity, and/or other molecular rearrangements occurring during presetting, impose additional constraints on molecular mobility, which delay onset of the flow regime and increase the time constant of relaxation at a given temperature. The thermosetting characteristics of PA66 fibers are very similar to those of poly(ethylene terephthalate) fibers. For both polymers, superposing the curves of fractional recovery vs. setting time at different temperatures produce satisfactory master curves, without the need for vertical shifting of the data. Arrhenius plots yield approximate activation energies for the thermosetting flow process of 35-65 kcal/mol in PA66 and 95-115 kcal/mol in PET.     

Structure characterization of heat set and drawn polyamide 66 fibers by FTIR spectroscopy

Structural changes that occur during thermally induced and strain induced crystallization of polyamide 66 fibers were studied by infrared spectroscopy, density measurement and optical microscopy. Two bands at 924 and 1136 cm^–1 were shown to arise from the amorphous phase and assignment of the bands at 936 and 1200 cm^–1 to the crystalline phase were confirmed. We demonstrated that two different infrared spectroscopic methods could be used to determine the total crystallinity of polyamide 66 fibers. One is a calibration method in which the band ratio of 1200 and 1630 cm^–1 is plotted against the crystallinity measured by density measurements. The other one is an independent infrared method. Crystallinity obtained by the independent infrared spectroscopic method showed good agreement with crystallinity observed by density measurement. Infrared dichroism was used to obtain the crystalline orientation using the band at 936 cm^–1. The transition moment angle of 48° was found for the band at 936 cm^–1 with respect to chain axis. Amorphous orientation was obtained using Stein’s equation. Received: 18 September 2000 / Reviewed and accepted: 20 September 2000     

Cognitive deficits in docosahexaenoic acid-deficient rats.

This study investigated the influence of brain docosahexaenoic acid (DHA) deficiency on simple and complex olfactory-based learning and memory in 2nd generation (F2) adult male rats. Rats raised and maintained on either an n-3-adequate or an n-3-deficient diet were tested for acquisition of an olfactory learning set and an olfactory memory task, and for motivation to obtain a water reward. Despite a 76% decrease in brain DHA, n-3-deficient rats were able to acquire most simple 2-odor discrimination tasks but were deficient in the acquisition of a 20-problem olfactory learning set. This deficit could not be attributed to changes in sensory capacity but, instead, appeared to represent a deficit in higher order learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

云环境驱动全新安全方法

当今时代,私人邮件、照片、音乐日益增多,企业与政府部门的金融系统及客户记录也变得日益复杂,这些均表明信息无时无刻不在飞速增长,而同时管理信息也就变得日益艰难了。当然,信息已经不仅存在于你桌上的文件夹里,而是在你的手机、电脑或者上网本里。因为,人们希望无论是在办公室里、在家里或是在路上,都能随时随地接触到这些信息。     

Thermal and flow effects during adsorption in conventional,diluted and annular packed beds

Previous investigations have shown a complex combination of thermal and flow effects during adsorption in highly loaded, narrow packed beds. Respective conditions were realized by packing relatively large zeolite particles in a narrow tube (which causes wall channelling) and adsorbing water vapour from air on the particles (which is highly exothermic). The present work extends the investigation to novel column configurations with purposely altered conditions of heat generation and flow—namely to diluted beds, annular beds and beds consisting of coated particles. Experimental results obtained by near infrared tomography are compared with the results of breakthrough experiments in conventional columns and with numerical calculations. The latter are conducted with a non-isothermal, two-dimensional model that not only considers the increase of porosity and flow velocity near the tube wall, but also expresses the effective transport coefficients as functions of the radial coordinate. The model provides reasonable accuracy under conditions for which the usual plug-flow assumption is questionable.     

1200V、550A碳化硅DMOSFET对偶模块的特性

碳化硅[SiC]优越的材料性质为电力电子器件提供了比传统的硅基器件更优越的性能。最近开发了一种1200V、50A的SiC DMOSFET已用于开关电路。在此基础上,又研制了一种1200V,550A完全用SiC的对偶模块。本文阐述其中每个开关用11个SiC DMOSFET和11个SiC JBS*组成的先进对偶模块的实验特性。     

Efficient recursive least squares parameter estimation algorithm for accurate nanoCMOS variable gain amplifier performances

ABSTRACT

With the aggressive scaling of integrated circuit technology, parametric estimation is a critical task for designers who looked for solutions to the challenges of some Nanoscale CMOS parameters. This paper presented the prediction of primary parameters of CMOS transistor for 16 nm to 10 nm process nodes using both of Bisquare Weights (BW) method and a novel recursive least squares (RLS) parameter estimation algorithm. The proposed RLS algorithm consists of the minimisation of a quadratic criterion relating to the prediction error in order to attain the best estimated parameters of the developed mathematical model. The obtained results thanks to the proposed RLS algorithm were better than those reached using the BW method. Comparisons between Predictive Technology Model (PTM) data and parameters estimated with RLS algorithm were made to check the validity and the consistency of the proposed algorithm. These predicted primary parameters were helpful to estimate and to optimise the performances of the Variable Gain Amplifier (VGA) which was a basic circuit element with a key role in the design of new upcoming receivers.