Optical properties of Zitex in the infrared to submillimeter

The results of measurements of the refractive index and power attenuation coefficient of Zitex at 290, 77, and 4 K in the spectral region from 1 to 1000 microm are presented. Zitex is a porous Teflon sheet with a filling factor of approximately 50% and is manufactured in several varieties as a filter paper. Zitex is found to be an effective IR block, with thin (200-microm) sheets transmitting less than 1% in the 1-50-microm range while attenuating < or = 10% at wavelengths longer than 200 microm. Some variation in the cutoff wavelength is seen, tending to be a shorter-wavelength cutoff for a smaller pore size. In addition, the thermal conductivity of Zitex at cryogenic temperatures has been measured and is found to be roughly one half that of bulk Teflon. Finally, its dielectric constant has been measured in the submillimeter as n = 1.20, resulting in extremely low dielectric reflection losses. As a result, Zitex is particularly useful as an IR blocking filter in low-noise heterodyne receivers; in the millimeter-wave range (lambda > or = 850 microm or nu < or = 350 GHz) the attenuation of alpha < or = 0.01 cm(-1) for a 3.5-mm thickness filter of Zitex G125 would raise receiver noise temperatures by <1 K.     

Drinking Water Treatment Plant Design Incorporating Variability and Uncertainty

Both inherent natural variability and model parameter uncertainty must be considered in the development of robust and reliable designs for drinking water treatment. This study presents an optimization framework for investigating the effects of five variable influent parameters and three uncertain model parameters on the least-cost treatment plant configuration (contact, direct, or nonsweep conventional filtration) that reliably satisfies an effluent particulate matter concentration constraint. Incorporating variability and uncertainty within the decision-making framework generates information for investigating: (1) impacts on total cost and treatment reliability; (2) shifts on the least-cost treatment configuration for providing reliable treatment; and (3) the importance of the individual variable and uncertain parameter distributions for reliably satisfying an effluent water quality constraint. Increasing the magnitude of influent variability and model parameter uncertainty results in a greater expected design cost due, generally, to increases in process sizing required to reliably satisfy the effluent concentration constraint. The inclusion of variability and uncertainty can also produce a shift in the locations of the least-cost configuration regions, which are dependent on the expected influent water quality and the magnitude of variability and uncertainty. The additional information provided by incorporating the variable and uncertain parameters illustrates that parameter distributions related to the primary removal mechanism are critical, and that contact and direct filtration are more sensitive to variability and uncertainty than conventional filtration.     

基带SoC的系统解决方案

SoC设计的复杂度在不断增加,同时,市场的压力对产品的质量和交付时间都提出了更加苛刻的要求。本文将以TTPCom公司的CBEmacro3G调制解调器为例,介绍ARM公司在面对当今无线SoC芯片平台设计挑战时的解决方案。     

需求编写十佳经验

需求表述不善可带来毁灭性影响,其所引发的多米诺效应可导致耗时返工、延期交付及预算超支,严重的还可造成业务违规甚至人员伤亡。近年来,随着ISO9000、CMM/CMMI、六西格码等国际标准逐步引入中国,“需求管理”正成为中国当前工程应用和商业热域的热点。目前,有关需求管理的实践大量应用于软件开发工程等领域,软件开发团队在开始一个新的项目之前,会通过详细的用户     

Small is Smarter: Nano MRI Contrast Agents – Advantages and Recent Achievements

Many challenges for advanced sensitive and noninvasive clinical diagnostic imaging remain unmatched. In particular, the great potential of magnetic nano‐probes is intensively discussed to further improve the performance of magnetic resonance imaging (MRI), especially for cancer diagnosis. Based on recent achievements, here the concepts of magnetic nanoparticle‐based MRI contrast agents and tumor‐specific imaging probes are critically summarized. Advances in their synthesis, biocompatible chemical and biofunctional surface modifications, and current strategies for further developing them into multimodality imaging probes are discussed. In addition, how engineered versus unintended surface coatings such as protein coronas affect the biocompatibility and performance of MRI nano‐probes is also considered. To stimulate progress in the field, future strategies and relevant challenges that still need to be resolved in the field conclude this review.     

An automated composite table algorithm considering zero liquid discharge possibility in water regeneration–recycle network

In this study, a novel Automated Composite Table Algorithm (ACTA) is developed for targeting the water regeneration–recycle network of single contaminant problem. The ACTA is based on Pinch Analysis, but is automated by taking into consideration the possibility of zero liquid discharge (ZLD) for the water network. In the existing literature, the targeting procedure for ZLD network is based on the graphical tool of Limiting Composite Curve (LCC). However, identification of key parameters (i.e. freshwater, wastewater, regenerated water flowrates, along with pre-regeneration concentrations) is very tedious for highly integrated water network system. The magnification around the turning point of LCC is required to identify the correct pinch points and targeting procedure is done iteratively until the reliable network targets can be determined. These limitations are now overcome by the ACTA, which is an improved version of Composite Table Algorithm that is capable of identifying key parameters algebraically for a given post-regeneration concentration. The newly developed ACTA is capable of handling a wide range of problems including ZLD and non-ZLD network, for both fixed load and fixed flowrate problems.     

A hierarchical approach to simulate the packing density of particle mixtures on a computer

In many fields of materials science it is important to know how densely a particle mixture can be packed. The “packing density” is the ratio of the particle volume and the volume of the surrounding container needed for a random close packing of the particles. We present a method for estimating the packing density for spherical particles based on computer simulations only, i.e. without the need for additional experiments. Our method is particularly suited for particle mixtures with an extremely wide range of particle diameters as they occur e.g. in modern concrete mixtures. A single representative sample from such mixtures would be much larger than can be handled on present standard computers. In our hierarchical approach the diameter range is therefore divided into smaller intervals. Samples from these limited diameter intervals are drawn and their packing density is estimated from a simulated packing. The results are used to “fill” the interstices in the sample from the next larger particle interval. To account for the interaction between particles of different sizes we include larger particles into the sample of smaller ones. The larger ones act as part of the boundary during the packing. Thus we obtain more realistic estimates of how dense a fraction of particles can be packed within the whole mixture. The focus of this paper is on the divide-and-conquer approach and on how the simulation results from the fractions can be collected into an overall estimate of the packing density. We do not go into details of the simulation technique for the single packing. We compare our results to some experimental data to show that our method works at least as good as the classical analytical models like CPM without the need for any experiments.     

The effect of difference oriented communication on the subjective validity of an in-group norm: Doc can treat the group.

The subjective group dynamics model predicts that in-group deviants who violate in-group norms that differentiate between the in-group and the out-group threaten the in-group's public image and its sense of validity. Previous research has shown that, to reduce this threat, group members attempt to symbolically marginalize in-group deviants through negative evaluation. In the current study (N = 107), the effect of another form of symbolic marginalization (difference oriented communication) is investigated. The findings support the subjective group dynamics model by showing that group members whose communications to deviants highlighted differences experienced a subsequent increase in subjective validity of in-group norms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Surface Chemical Characterization of Ceramic Materials: Adsorption and Degradation of 3,6,9-Trioxadecanoic Acid on Nano-ZrO2

This paper deals with the specific interaction of the dispersant 3,6,9-trioxadecanoic acid (TODA) with nano-ZrO₂ surfaces. Special interest was directed towards degradation behavior of the adsorbates and its influence on dispersant capabilities of TODA regarding stabilization of ethanolic nano-ZrO₂ suspensions. ZrO₂ adsorption sites and the adsorbates formed are examined by diffuse reflectance infrared Fourier transform spectroscopy, thermal analysis, ¹H-, and ¹³C-cross polarization magic angle spinning solid-state nuclear magnetic resonance spectroscopy. ¹H as well as ¹³C-chemical shifts and the configurations of the corresponding adsorbed TODA species on zirconia sites are predicted by means of density functional theory quantum chemical calculations for supporting the interpretation of the experimental spectral data obtained. This work shows that combination of analytical and theoretical methods is an effective approach characterizing surface chemical properties of ceramic materials, determining sorption properties of organic process additives, investigating correspondent elementary and degradation reactions as well as clarifying cause-effect relationships in ceramic processes.