Spelling suggestions: "subject:"monocolumn"" "subject:"longcolumn""
471 |
Experimental study of beam to concrete-filled elliptical steel tubular column connectionsYang, Jie, Sheehan, Therese, Dai, Xianghe, Lam, Dennis 25 June 2015 (has links)
Yes / This paper investigated the rotation behaviour of simply bolted I-beam to concrete-filled elliptical steel tubular (CFEST) column connections experimentally. Ten different joint assemblies were tested to failure, with a constant axial compressive load applied to the column and upwards concentrated loads at the beam ends. All of the steel tubes were hot-finished and had a cross-sectional aspect ratio of 2. The orientation of the column and the arrangement of the stiffening plates were taken into consideration. Moment versus rotation relationships and failure modes were compared for each joint, highlighting the benefits of using core concrete and stiffeners in these connections.
|
472 |
Low Cost Electronically Steered Phase Arrays for Weather ApplicationsSanchez-Barbetty, Mauricio 01 February 2011 (has links)
The Electronically Steered Phased Array is one of the most versatile antennas used in radars applications. Some of the advantages of electronic steering are faster scan, no moving parts and higher reliability. However, the cost of phased arrays has always been prohibitive - in the order of $1M per square meter. The cost of a phased array is largely impacted by the cost of the high frequency electronics at each element and the cost of packaging. Advances in IC integration will allow incorporating multiple elements such as low noise amplifier, power amplifier, phase shifters and up/down-conversion into one or two ICs. Even though the cost for large quantities of ICs (both Silicon and GaAs) has lowered, the high cost of IC packaging and the array backplane still make the use of phase arrays for radar applications costly. The focus of this research is on techniques that reduce the packaging and the backplane cost of large electronically steered arrays. These techniques are based on simplified signal distributions schemes, reduction of layers in the backplane and use of inexpensive materials. Two architectures designed based on these techniques, as well as a novel BGA active antenna package for dual polarized phased arrays are presented. The first architecture, called the series fed row-column architecture, focuses on the reduction of phase shifters and control signals used in the backplane of the array. The second architecture, called the parallel plate feed architecture, is based on a simplified scheme for distribution of the local oscillator signal. A prototype making use of each one of these architectures is presented. Analysis of advantages and disadvantages of each of these architectures is described. The necessity of cost reduction is a factor that can possibly impact the polarization performance of the antenna. This factor is a motivation to study and develop calibration techniques that reduce the cross-polarization of electronically steered phased arrays. Advances on Interleaving Sparse Arrays, a beam forming technique for polarization improvement/correction in phased arrays, are also presented.
|
473 |
Pharmaceutical analysis and in-vitro aerodynamic characterisation of inhaled theophylline formulations containing drug particles prepared by supercritical fluid processing. Chromatographic, spectroscopic, and thermal analysis of micron-sized theophylline particles prepared by supercritical fluid technology and in-vitro evaluation of their performance as inhaled dry powder formulations.Mohamed, Noha N.A. January 2009 (has links)
The aim of this work is to study the in-vitro aerodynamic performance of a new inhaled theophylline formulation prepared by supercritical fluids technique.
For the analysis of the output from the in-vitro tests (and further in-vivo tests) a new, fast, sensitive high performance liquid chromatographic (HPLC) method was developed and validated for the determination of theophylline and other related derivatives in aqueous and urine samples using new packing materials (monolithic columns). These columns achieve efficient separation under lower backpressure and shorter time comparing to other traditionally or newly introduced C18 columns.
Solution enhanced dispersion by supercritical fluid (SEDS) process has been applied for the production of anhydrous theophylline as pure crystals in the range 2-5 ¿m to be used as new inhaled dry powder formulation for asthma. Fifteen theophylline samples have been prepared under different experimental conditions.
The drug produced by this method has been subject to a number of solid-phase analytical procedures designed to establish the crystal structure [X-ray powder diffraction (XRPD)], the structure and conformation [(FTIR), Fourier-transform Raman spectroscopy (FT-Raman)], and the morphology and particle size [scanning electron microscope (SEM)]. While, thermal gravimetric analysis (TGA), and differential scanning calorimetry (DSC) have been used to monitor any phase transition or polymorphic changes after processing. All these analytical techniques gave a satisfactory indication of the solid-state chemistry of the processed particles and assess the development of new inhalation product.
The performance of inhaled SEDS theophylline with or without a carrier was evaluated using the developed HPLC method. Three samples having different particle sizes were selected out of the prepared powders by SEDS technique to be tested. The dose sampling unit and the Anderson Cascade Impactor were used to determine the in-vitro emitted dose and the deposition profiles of SEDS samples, respectively. The effect of different inhalation flows was studied using two different flows 28.3, and 60 L min-1 with 4 L inhalation volume. Different DPI devices were investigated in this study; Easyhaler® and Spinhaler®. The particle size has an important effect on the aerodynamic behaviour and deposition profile of inhaled drug, the smaller the particles the greater the total lung deposition. The presence of a carrier improves the respirable fraction for all the tested formulations. / Egyptian Ministry of Higher Education
|
474 |
Formoptimierung von Druckgliedern aus Beton und StahlbetonSchmidt, Angela 15 November 2022 (has links)
Heutzutage werden die allermeisten Beton- und Stahlbetonstützen mit einem rechteckigen oder kreisförmigen Querschnitt und einem konstanten Verlauf über die Stützenlänge ausgeführt. Entsprechend der konstruktiven Randbedingungen und der vorhandenen Belastung existieren jedoch häufig stärker und schwächer beanspruchte Bereiche innerhalb eines Druckglieds. In der vorliegenden Arbeit wird daher eine Formoptimierung von (Stahl-)Betonstützen vorgenommen und das resultierende Volumeneinsparungs- bzw. Laststeigerungspotenzial aufgezeigt und analysiert. Hierfür werden charakteristische Lastfälle eines typischen Stahlbetonskelettbaus herangezogen. Vorbetrachtungen führten dazu, dass sich die Untersuchungen vor allem auf planmäßig zentrisch gedrückte, knickgefährdete Stützen sowie auf exzentrisch gedrückte Stützen, bei denen die Biegebeanspruchung infolge einer Rahmenwirkung des Tragsystems resultiert, konzentrieren.
Für zentrisch belastete, knickgefährdete Stützen existieren in der Literatur bereits Ergebnisse zu einer Form- und Querschnittsoptimierung bei bruchsicherem und linear-elastischem Materialverhalten. Die Angaben wurden aufbereitet, überprüft und mit Untersuchungen zu den Auswirkungen einer elastischen Lagerung, einer Imperfektion sowie zum Einfluss eines nichtlinearen Materialverhaltens ergänzt. Die theoretischen Betrachtungen ergaben, dass die optimale Stützenform von der jeweiligen Knickfigur abhängt und somit entsprechend der Lagerungsbedingungen variiert. Für die Verifikation wurden zunächst Vorversuche an rechteckigen Stützen mit konstantem Verlauf und unterschiedlicher Bauteillänge durchgeführt. Diese dienten zu einer besseren Abschätzung des Stabilitätsverhaltens in Abhängigkeit der
Schlankheit, der vorhandenen Imperfektionsgröße sowie zur Bestimmung des erzielten Einspanngrades für den gewählten Versuchsstand. Aufbauend auf den Ergebnissen erfolgte die experimentelle Überprüfung des Form- und Querschnittseinflusses. Die in den Versuchen ermittelten Traglasten konnten in allen Fällen sehr gut mit den theoretischen Ansätzen der Elastizitätstheorie vorhergesagt und nachgerechnet werden.
Die Formoptimierung von exzentrisch gedrückten Stützen wurde für unterschiedliche Verhältnisse einer Momenten- und Normalkraftbeanspruchung durchgeführt. Um eine Abgrenzung zu den Betrachtungen des Stabilitätsversagens zu erzielen, beschränken sich die Untersuchungen auf ein eintretendes Materialversagen. Neben der Formfindung wird entsprechend der Beanspruchung auch eine geeignete Materialkombination gewählt, bei der sowohl der Stahl als auch der Beton möglichst ausgelastet werden. Die Optimierung erfolgt iterativ an einer über die Höhe segmentierten Stütze unter dem Kriterium, einen gleichmäßigen Spannungszustand im Bauteil zu erreichen. Die so gewonnenen optimierten Stützenformen orientieren sich an dem Biegemomentenverlauf. Für die Verifikation der Ergebnisse wurde ein Lastfall experimentell untersucht. Anhand dieser Versuchsreihe konnte das gewählte Berechnungs- und Optimierungsverfahren bestätigt werden.
|
475 |
An Optimization Study of an Intermittent-Flow Multistage Fluidized Ion Exchange Column with Fluid Diode DowncomersEgan, Stephen Martin 10 1900 (has links)
<p> An optimization study of an intermittent-flow multistage fluidized ion exchange column was performed using a stochastic approximation method. A new type of downcomer, a fluid diode, was designed and employed to alleviate liquid bypassing through the downcomer. The well known ion exchange system, H⁺/Na⁺ exchange on Dowex 50W resin, was used in this work. </p> <p> The volumetric efficiency of the system was optimized with regard to certain column and diode parameters. A maximum volumetric efficiency of 71.8 hr⁻¹ was obtained for the following conditions: </p> <p> average liquid flowrate = 3661 ml/min ; </p> <p> resin flowrate = 56.1 gm/min ; </p> <p> plate spacing 11.43 cm ; </p> <p> lateral diode displacement= 0.794 cm. </p> <p> Experiments have shown that a 78.2% increase in volumetric efficiency was achieved by use of the fluidic diode downcomers. </p> / Thesis / Master of Engineering (ME)
|
476 |
Purification of fuel grade Dimethyl Ether in a ready-to-assemble plantBallinger, Sarah January 2016 (has links)
Due to the remote and dispersed nature of Alberta’s oil wells, it is not economical for the energy industry to capture all of the solution gas produced and as a result, the gas is being flared and vented in significant amounts. The objective of this research is to aid in the conversion of solution gas into dimethyl ether (DME) in a remote location by designing a distillation column that purifies DME and its reaction by-products, carbon dioxide, methanol and water.
In order to develop an implementable solution, the distillation equipment must fit inside of a 40-foot shipping container to be transported to remote locations. Given the size constraint of the system, process intensification is the best strategy to efficiently separate the mixture. Several process intensification distillation techniques are explored, including semicontinuous distillation, the dividing wall column (DWC) and a novel semicontinuous dividing wall column (S-DWC).
The traditional semicontinuous distillation column purifies DME to fuel grade purity, however the other components are not separated to a high enough grade given the height constrain of the system. The DWC and S-DWC both purify DME to its desired purity along with producing high purity waste streams. The S-DWC purifies the reaction intermediate methanol to a grade slightly higher than the DWC and is pure enough to recycle back to the reactor.
An economic comparison is made between the three systems. While the DWC is a cheaper method of producing DME, the trade-off is the purity of the methanol produced.
Overall, this research shows that it is possible to purify DME and its reaction by-products in a 40-foot distillation column at a cost that is competitive with Diesel. / Thesis / Master of Applied Science (MASc)
|
477 |
Improvement Of Rotation Capacity Of Composite Beam-To-HSS Column Connections Using External Horizontal StiffenersAfshar Arjmand, Mahdi 01 December 2023 (has links) (PDF)
Improvement of Rotation Capacity of Composite Beam-to-HSS Column Connections Using External Horizontal Stiffeners
Mahdi Afshar Arjmand
This thesis focuses on the analysis of out-of-plane deformation (OOP) in column flange located in the panel zone of composite beam-to-column steel connection, as a critical aspect of steel structural engineering. This type of connection is an integral component of steel structures, and understanding their behavior is essential for ensuring safety and performance. The investigation involves examining the causes, factors influencing, and potential mitigation strategies for out-of-plane deformation of HSS flange column in these connections. Beam-to-column connections play a vital role in transferring loads and maintaining structural stability. Out-of-plane deformation, where the flange displaces from its primary plane, can compromise the connection's performance. This study aims to shed light on the mechanisms causing out-of-plane deformation and explore techniques to minimize its effects. Out-of-plane deformation of column flange connections can result from various factors, including eccentric loading, bending moments, torsion, and material properties. Understanding these causes is crucial for accurate analysis and design. Analytical methods and numerical simulations, such as finite element analysis (FEA), are employed to predict and quantify out-of-plane deformation. Models are created to represent real-world connections, enabling the exploration of their behavior under different loads and conditions. The study investigates strategies to mitigate out-of-plane deformation, such as adding horizontal stiffeners, or vertical stiffeners. These approaches aim to enhance the column flange’s resistance to out-of-plane displacements and improve overall structural performance. Real-world case studies of steel beam to-column connections are analyzed to demonstrate the effects of out-of-plane deformation and the efficacy of mitigation strategies. The results highlight the importance of accurate analysis and design to ensure connection integrity. Based on the findings, the study proposes design guidelines for flange-column connections to minimize out-of-plane deformation. These guidelines provide engineers with insights into optimizing connection design and ensuring stability under varying loads.
The unique characteristic of beam-to-HSS column connections is the out-of-plane deformation of the HSS column flange at the beam web-to-column flange interface which can reduce contribution of the connection web to the overall resistance of the connection. To explore effect of the column flange OOP deformation, performance of three connection types, namely composite beam-to-HSS column connection, composite beam-to-HSS column connection with slab-column gap, and bare beam-to-HSS column connections are evaluated using pre-validated 3D finite element (FE) simulations. FE models can simulate low-cycle fatigue and post-rupture behavior of the connection. Comprehensive global and local responses are presented and discussed. It is found that column compactness, i.e., column’s width-to-thickness ratio, has considerable effect on maximum moment capacity, rotation capacity, post rupture residual capacity and energy dissipation capability of the connection. On the other hand, external horizontal stiffeners can significantly increase the rotation capacity of the connection. External horizontal stiffeners in steel beam-to-column connections are crucial for boosting structural efficiency and load-bearing capacity. Carefully designed, accurately placed, and securely attached, they ensure a reliable and safe system capable of withstanding diverse loads and environmental conditions, contributing to the long-term safety and stability of the entire steel structure.
|
478 |
Screening of HETP test conditions and resin storage solutions for HICRonnerfors, Lise-Lotte January 2023 (has links)
Hydrophobic interaction chromatography (HIC) is a common purification method for biological drug substances. For continuous monitoring the quality of the purification, a column performance test is carried out to test the packing of the resin. The packing integrity is commonly tested between runs by measuring the Hight Equivalent to a Theoretical Plate (HETP) by injecting a small volume of a tracer solution (spike) that gives a change in conductivity. The column performance test provides useful information regarding the packing quality that could be used for troubleshooting before a purification is performed since a well packed gel is essential for an effective purification. During this thesis project a screening of suitable test conditions for a HETP test for a HIC column was performed. The developed HETP test were then investigated if it could be combined with the storage of the resin or if the packing is affected by the test conditions. Factors such as spike volume, flow rate and the concentration of the elute and spike solution, were considered. 0.1 M NaOH elute and 0.15 M NaCl as spike solution gave the best result based on HETP and the asymmetry of the conductivity peak. A test purification with the new HETP test conditions compared with the old method were then carried out to verify that the quality of the purification is not affected. The purification showed promising result and implementation of a more convenient storage solution and HETP test would be possible without changing the product quality.
|
479 |
Integrating dictionaries in a column-oriented database.Vestberg, Melinda January 2023 (has links)
In today's data-driven world, managing large volumes of data has become a common challenge. Data-driven businesses often face the task of effectively handling and analysing such extensive datasets when real-time analysis plays a crucial role to make informed decisions. Column-oriented databases have risen in popularity as a preferred storage and analytics solution. Elisa Polystar, for instance, uses ClickHouse, a column-oriented database to provide network and service assurance solutions in their Kalix product. One of the advantages of using column-oriented databases, including ClickHouse, is the availability of compression techniques. Dictionary is an in-memory key-value structure which can be stored completely or partially in RAM and can be used in queries. This thesis conducts a series of query-based experiments to evaluate the performance of Kalix when utilising dictionary. Results show that compared to the traditional left outer join, the dictionary version performed significantly better in five queries for both query duration and memory usage. At its best, the dictionary performs 26 times faster and consumes 1526 times less memory.
|
480 |
Structural and Lithological Controls on the Hydrologic Pathways in the Great Savannah Cave System, McClung Cave, Lewisburg, West Virginia, USAAl Salmi, Safa 05 June 2023 (has links)
No description available.
|
Page generated in 0.0413 seconds