• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 300
  • 234
  • 199
  • 26
  • 20
  • 14
  • 10
  • 9
  • 7
  • 6
  • 4
  • 4
  • 4
  • 3
  • 3
  • Tagged with
  • 981
  • 148
  • 106
  • 100
  • 93
  • 89
  • 74
  • 72
  • 56
  • 53
  • 45
  • 42
  • 42
  • 41
  • 40
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
421

A Global Preconditioning Method for the Euler Equations

Yildirim, B. Gazi 02 August 2003 (has links)
This study seeks to validate a recently introduced global preconditioning technique for the Euler equations. Energy and enthalpy equations are nondimensionalized by means of a reference enthalpy, resulting in increased numerical accuracy for low-speed flows. A cellbased, finite volume formulation is used, with Roe flux difference splitting and both explicit and implicit time integration schemes. A Newton-linearized iterative implicit algorithm is implemented, with Symmetric Gauss-Seidel (LU/SGS) nested sub-iterations. This choice allows one to retain time accuracy, and eliminates approximate factorization errors, which become dominant at low speed flows. The linearized flux Jacobians are evaluated by numerical differentiation. Higher-order discretization is constructed by means of the MUSCL approach. Locally one-dimensional characteristic variable boundary conditions are implemented at the farfield boundary. The preconditioned scheme is successfully applied to the following traditional test cases used as benchmarks for local preconditioning techniques: point disturbance, flow angle disturbance, and stagnation point arising from the impingement of two identical jets. The flow over a symmetric airfoil and a convergentdivergent nozzle are then simulated for arbitrary Mach numbers. The preconditioned scheme greatly enhances accuracy and convergence rate for low-speed flows (all the way down to M ≈ 10E − 4). Some preliminary tests of fully unsteady flows are also conducted.
422

Accuracy Study of a Free Particle Using Quantum Trajectory Method on Message Passing Architecture

Vadapalli, Ravi K 13 December 2002 (has links)
Bhom's hydrodynamic formulation (or quantum fluid dynamics) is an attractive approach since, it connects classical and quantum mechanical theories of matter through Hamilton-Jacobi (HJ) theory, and quantum potential. Lopreore and Wyatt derived and implemented one-dimensional quantum trajectory method (QTM), a new wave-packet approach, for solving hydrodynamic equations of motion on serial computing environment. Brook et al. parallelized the QTM on shared memory computing environment using a partially implicit method, and conducted accuracy study of a free particle. These studies exhibited a strange behavior of the relative error for the probability density referred to as the transient effect. In the present work, numerical experiments of Brook et al. were repeated with a view to identify the physical origin of the transient effect and its resolution. The present work used the QTM implemented on a distributed memory computing environment using MPI. The simulation is guided by an explicit scheme.
423

Dynamic Characterization and Active Modification of Viscoelastic Materials

Zhao, Sihong 04 May 2011 (has links)
No description available.
424

Optimal summer camp layout

Bonifonte, Anthony January 2011 (has links)
No description available.
425

On incorporating heterogeneity in linkage analysis

Biswas, Swati January 2003 (has links)
No description available.
426

Combined Study of a New Processing Technique and Formulation of a High Energy Protein Supplement to Contribute to the U. N. Millennium Task Force’s Global Developmental Goal

Basu Kaul, Lopamudra Sanjay 19 December 2011 (has links)
No description available.
427

Development of a novel gastro-retentive delivery system using alfuzosin HCl as a model drug

Liu, Quan. January 2010 (has links)
The objectives of this project encompass the design and development of a drug delivery system to continuously deliver therapeutic agents from the stomach to the proximal region of the intestine. The delivery system designed would have sufficient gastric residence time together with near zero-order release kinetics. The physicochemical properties pertaining to the formulation development of the model drug (alfuzosin HCl) were evaluated. Excipients were selected based on the studies of their physicochemical properties and compatibility with the active ingredient. Gastro-retentive dosage forms have been the topic of interest in recent years as a practical approach in drug deliveries to the upper GI tract or for release prolongation and absorption. These dosage forms are particularly suitable for drugs that have local effects on the gastric mucosa in the stomach. Other candidates include drugs that are likely to be absorbed in the upper small intestine, or drugs that are unstable in basic environment of distal intestine and colon or those with low solubility at elevated pH conditions (i.e. weak bases). To develop a gastro-retentive delivery system the following steps were taken. First, to investigate the possible incompatibility issues between the model drug and excipients to be used for the delivery system. Stability and physicochemical properties of the active agent and its mixture with excipients were studied using analytical techniques such as Raman spectroscopy and Differential scanning calorimetry (DSC). No incompatibility issues were detected. Second, Kollidon SR as a relatively new release-rate controlling polymer was incorporated in the final formulation. For solid dosage form the ability of the final powder mix to flow well during manufacturing and the intrinsic characteristics that make it compressible are critical. The in-depth compaction study of Kollidon SR was assessed with the help of a compaction simulator. The flowability, swelling and erosion behavior together with release-rate retarding properties of Kollidon SR were also assessed. The final oral delivery system was based on Kollidon SR and Polyethylene Oxide (PEO) 303 as a monolithic matrix system. The noneffervescent monolithic matrix was made by direct compression. In vitro evaluation of the designed system released the active content in a near zero manner. The dosage form was bouyant in pH 2.0 acidic buffer with no floatation lag time which minimizes the possibility of early gastric emptying. / Pharmaceutics
428

Coverage increase in a plant-based BB cream formulation with natural pigments / Ökad täckning med en växtbaserad BB-krämformulering med naturliga pigment

Billot, Leelou Zoé January 2024 (has links)
Kaffe Bueno, ett bioteknologiskt start-up-företag dedikerat till framsteg inom naturliga och gröna produkter, fokuserar på att utnyttja den outnyttjade potentialen hos kaffebiprodukter genom grön kemi och bioteknik. Då endast 1% av kaffet används för bryggning, extraherar företaget lösliga och olösliga produkter genom en uppdelning mellan ett oljeutvinning och ett efterföljande vattenuttag, vilket bidrar till att sänka CO2-utsläppen per värde och en cirkulär ekonomi. Inom hudvård har Kaffe Bueno tidigare utvecklat en BB-kräm med återvunnen kaffesump för pigmentering och hudvårdsfördelar, men stötte på utmaningar när det gäller täckning jämfört med syntetiska BB-krämer, vilket ledde till målet med detta examensarbete. Målet med denna studie är att formulera en helt växtbaserad BB-kräm med optimal täckning, överträffa standarden satt av syntetiska kemiska BB-krämer. Den centrala fråga som styr forskningen är: "Vilka är de optimala formuleringsrstrategierna och växtbaserade ingredienserna för att uppnå högsta täckning i en helt växtbaserad BB-kräm samtidigt som stabilitet säkerställs?". Denna forskning stämmer överens med den globala kosmetikindustrins växande efterfråga av hållbara, växtbaserade formuleringar, som svar på konsumenternas preferenser för miljövänliga produkter. Forskningen inkluderar utveckling av en växtbaserad vit baskräm utan titanoxid eller zinkoxid, och sedan användning av naturliga pigment som KAFFAGE® för att justera färgen, säkerställa hållbarhet, täckning och stabilitet över tid, vid ljusexponering och användning. Sammanfattningsvis formulerades under denna studie framgångsrikt en växtbaserad BB-kräm med täckning jämförbar med marknadsstandarder, undvikande av traditionella järnoxider och med användning av hållbara ingredienser som KAFFAGE-BD®-pigment, även om användning av titandioxid (TiO2) fortfarande krävs. Forskningen betonade vikten av texturoptimering, färgmatchning och sensorisk perception, vilket positionerar BB-krämen som en pålitlig och mångsidig kosmetisk lösning. Framtida forskning bör prioritera undersökning av alternativ till TiO2, såsom mikrokristallin cellulosa, för att förbättra hållbarheten i BB-krämens formulering. / Kaffe Bueno, a bioscience startup company dedicated to advancing natural and green products, focuses on harnessing the untapped potential of coffee by-products through green chemistry and biotechnology. With only 1% of coffee utilized for brewing, the company extracts soluble and insoluble products through a partion between an oil extraction and a subsequent water extraction, contributing to lowering the CO2 emissions per value from coffee consumption and a circular economy. In skincare, Kaffe Bueno previously developed a Beauty Balm cream using ingredients from upcycled spent coffee grounds for pigmentation and skincare benefits, but faced challenges in achieving coverage comparable to synthetic BB creams, prompting the goal of this master thesis. The objective of this study is to formulate an all plant-based BB cream with optimal coverage, surpassing the standard set by synthetic BB creams. The central question guiding the research is: "What are the optimal formulation strategies and plant-based ingredients for achieving the highest coverage in an all plant-based BB cream while ensuring stability?". This research aligns with the global cosmetic industry's growing demand for sustainable, plant-based formulations, responding to consumer preferences for eco-friendly products. The research includes developing a white plant-based base cream without titanium dioxide or zinc oxide, and then utilizing natural pigments like KAFFAGE® to adjust the tint, ensuring sustainability, up-to-standard coverage, stability over time, light exposition and use. Tests conducted to validate the product’s performance and quality include a stability test, a sensory panel evaluation, a sweat test, and other relevant assessments to ensure the cream's effectiveness, user satisfaction, and compliance with industry standards. In conclusion, this study successfully formulated a plant-based BB cream with coverage comparable to market benchmarks, circumventing traditional iron oxides and relying on sustainable ingredients like KAFFAGE-BD®, even though the use of titanium dioxide (TiO2) is still needed. The research emphasized the importance of texture optimization, color matching, and sensory perception, highlighting the essential attributes for BB creams in general and positioning this particular BB cream as a reliable and versatile cosmetic solution. Future research should prioritize exploring alternatives to TiO2, such as microcrystalline cellulose, to enhance sustainability in BB cream formulations.
429

Dynamics and Control of Flexible Aircraft

Tuzcu, Ilhan 08 January 2002 (has links)
This dissertation integrates in a single mathematical formulation the disciplines pertinent to the flight of flexible aircraft, namely, analytical dynamics, structural dynamics, aerodynamics and controls. The unified formulation is based on fundamental principles and incorporates in a natural manner both rigid body motions of the aircraft as a whole and elastic deformations of the flexible components (fuselage, wing and empennage), as well as the aerodynamic, propulsion, gravity and control forces. The aircraft motion is described in terms of three translations (forward motion, sideslip and plunge) and three rotations (roll, pitch and yaw) of a reference frame attached to the undeformed fuselage, and acting as aircraft body axes, and elastic displacements of each of the flexible components relative to corresponding body axes. The mathematical formulation consists of six ordinary differential equations for the rigid body motions and one set of ordinary differential equations for each elastic displacement. A perturbation approach permits division of the problem into a nonlinear "zero-order Problem" for the rigid body motions, corresponding to flight dynamics, and a linear "first-order problem" for the elastic deformations and perturbations in the rigid body translations and rotations, corresponding to "extended aeroelasticity." Due to computational speed advantages, the aerodynamic forces are derived by means of strip theory. The control forces for the flight dynamics problem are obtained by an "inverse" process. On the other hand, the feedback control forces for the extended aeroelasticity problem are derived by means of LQG theory. A numerical example corresponding to steady level flight and steady level turn maneuver is included. / Ph. D.
430

The use of SEC-UV in formulation optimization for a protein-peptide conjugate drug candidate

Imedashvili, Sumay January 2024 (has links)
Many companies, including Strike Pharma, are developing biologicals for individualized immunotherapeutic cancer treatments. The possibility to combine a bispecific antibody with a myriad of endogenous antigenic peptides opens the doors for highly personalized therapies. Setting up and using analytical assays is key to evaluate aggregation and overcome aggregation patterns of biologicals during CMC development. The aim of this project was to assess size exclusion chromatography (SEC) as an analytical method and subsequently evaluate several drug formulations that could be suitable for subcutaneous administration of a peptide and antibody conjugate mix. The formulations were based on a 25 mM histidine buffer pH 6.0, that had been optimized for the antibody alone, with different additives. By utilizing SEC coupled to UV-detection at 280 nm, aggregates were detected and quantified. The most effective excipients were dimethyl sulfoxide, polyethylene glycol 400 and arginine. Two different peptide-tags were compared and the pTag9mer-mut2 variant was more favorable than pTag9mer-mut1 in limiting aggregate formation with highest success rates at 1.5 mg/mL protein concentrations and the fulfillment of the high molecular weight ≤ 5% criterion. Combining antibody and peptide containing pTag9mer-mut1 in a pH 9.0 histidine buffer with added arginine engendered the least aggregates compared to any pH 6.0 formulation. However, the instability of the antibody in pH 9.0 and the risk of deamidation makes this less suitable. Future considerations include changing the administration method or using pump injection strategy, which allows higher injection volumes to limit aggregation by lowering protein concentrations.

Page generated in 0.0302 seconds