3,252 research outputs found

    Hazardous Waste Reduction Continuation

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    A silicone manufacturing process yields two-phase wastewater, of which the aqueous phase flashes at 2°C primarily due to hexamethyldisiloxane (HMDSO). To be classified as non-hazardous and immediately disposable, it must flash above 60°C. Project objectives entailed identifying a method and then designing a prototype for on-site aqueous phase treatment, removing enough HMDSO for non-hazardous disposal. The previous team’s proposal was gravity separation, NaCl extraction, and feeding through an activated carbon packed bed. Extraction proved ineffective, packed bed outlet samples flashed at 52°C, and HMDSO quantification methodology was incorrect. From titration, wastewater was determined to be 3.3 ± 0.2 wt.% aqueous ammonia. This ammonia concentration was used to spike water samples prepared with variable HMDSO concentrations with the target of determining HMDSO concentrations in the treated water that would flash above 60°C. Without ammonia, 36 ppm HMDSO passed the flash point test. Adding ammonia expanded the tolerance to \u3e50 ppm HMDSO. Waste was subjected to various treatment method combinations: adsorption on activated carbon, reaction with bleach, and semi-batch gas stripping with nitrogen in column packed with ceramic saddles. Flash point results are given below. The process very nearly satisfies the 60°C flash point goal, with some variation. To correctly quantify HMDSO, standard addition was used with GC. Consequently, the proposed treatment process is gravity phase separation, activated carbon packed bed treatment, and then semi-batch stripping with nitrogen. Recommendations for future work are to explore amendments to the proposed procedure, including time-dependent mass transfer analysis, counter-current gas stripping through a packed bed, and implementation of automated sample preparation and testing.https://scholarscompass.vcu.edu/capstone/1154/thumbnail.jp

    Moment method analysis of linearly tapered slot antennas: Low loss components for switched beam radiometers

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    A Moment Method Model for the radiation pattern characterization of single Linearly Tapered Slot Antennas (LTSA) in air or on a dielectric substrate is developed. This characterization consists of: (1) finding the radiated far-fields of the antenna; (2) determining the E-Plane and H-Plane beamwidths and sidelobe levels; and (3) determining the D-Plane beamwidth and cross polarization levels, as antenna parameters length, height, taper angle, substrate thickness, and the relative substrate permittivity vary. The LTSA geometry does not lend itself to analytical solution with the given parameter ranges. Therefore, a computer modeling scheme and a code are necessary to analyze the problem. This necessity imposes some further objectives or requirements on the solution method (modeling) and tool (computer code). These may be listed as follows: (1) a good approximation to the real antenna geometry; and (2) feasible computer storage and time requirements. According to these requirements, the work is concentrated on the development of efficient modeling schemes for these type of problems and on reducing the central processing unit (CPU) time required from the computer code. A Method of Moments (MoM) code is developed for the analysis of LTSA's within the parameter ranges given

    Bulk binding approach for PMIPv6 protocol to reduce handoff latency in IoT

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    Mobility management protocols are very essential in the new research area of Internet of Things (IoT) as the static attributes of nodes are no longer dominant in the current environment. Proxy MIPv6 (PMIPv6) protocol is a network-based mobility management protocol, where the mobility process is relied on the network entities, named, Mobile Access Gateways (MAGs) and Local Mobility Anchor (LMA). PMIPv6 is considered as the most suitable mobility protocol for WSN as it relieves the sensor nodes from participating in the mobility signaling. However, in PMIPv6, a separate signaling is required for each mobile node (MN) registration, which may increase the network signaling overhead and lead to increase the total handoff latency. The bulk binding approaches were used to enhance the mobility signaling for MNs which are moving together from one MAG to another by exchanging a single bulk binding update message. However, in some cases there might be several MNs move at the same time but among different MAGs. In this paper, a bulk registration scheme based on the clustered sensor PMIPv6 architecture is proposed to reduce the mobility signaling cost by creating a single bulk message for all MNs attached to the cluster. Our mathematical results show that the proposed bulk scheme enhances the PMIPv6 performance by reducing the total handoff latency

    Novel anisotropic continuum-discrete damage model capable of representing localized failure of massive structures. Part II: identification from tests under heterogeneous stress field

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    In Part I of this paper we have presented a simple model capable of describing the localized failure of a massive structure. In this part, we discuss the identification of the model parameters from two kinds of experiments: a uniaxial tensile test and a three-point bending test. The former is used only for illustration of material parameter response dependence, and we focus mostly upon the latter, discussing the inverse optimization problem for which the specimen is subjected to a heterogeneous stress field.Comment: 18 pages, 12 figures, 6 table

    Canonical transformations in three-dimensional phase space

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    Canonical transformation in a three-dimensional phase space endowed with Nambu bracket is discussed in a general framework. Definition of the canonical transformations is constructed as based on canonoid transformations. It is shown that generating functions, transformed Hamilton functions and the transformation itself for given generating functions can be determined by solving Pfaffian differential equations corresponding to that quantities. Types of the generating functions are introduced and all of them is listed. Infinitesimal canonical transformations are also discussed. Finally, we show that decomposition of canonical transformations is also possible in three-dimensional phase space as in the usual two-dimensional one.Comment: 19 pages, 1 table, no figures. Accepted for publication in Int. J. Mod. Phys.

    Developmental biology: an array of new possibilities

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    Microarrays offer biologists comprehensive and powerful tools to analyze the involvement of genes in developmental processes at an unprecedented scale. Microarrays that employ defined sequences will permit us to elucidate genetic relationships and responses, while those that employ undefined DNA sequences (ESTs, cDNA, or genomic libraries) will help us to discover new genes, relate them to documented gene networks, and examine the way in which genes (and the process that they themselves control) are regulated. With access to broad new avenues of research come strategic and logistical headaches, most of which are embodied in the reams of data that are created over the course of an experiment. The solutions to these problems have provided interesting computational tools, which will allow us to compile huge data sets and to construct a genome-wide view of development. We are on the threshold of a new vista of possibilities where we might consider in comprehensive and yet specific detail, for example, the degree to which diverse organisms utilize similar genetic networks to achieve similar ends. (C) 2002 Elsevier Science Inc. All rights reserved

    REFLECTION HOLOGRAM FOR PARTICLE SIZE MEASUREMENT

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    Reflection hologram was used to record the transparent dynamic particle. By this method there is high protection to the optical devices. Another information about particle size and particle distribution has been obtained. The major limitation of in-line Fraunhofer hologram has been solved
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