998 resultados para solution accuracy


Relevância:

20.00% 20.00%

Publicador:

Resumo:

The aim of our study was to provide an innovative HS-GC/MS method applicable to the routine determination of butane concentration in forensic toxicology laboratories. The main drawback of the GC/MS methods discussed in literature concerning butane measurement was the absence of a specific butane internal standard necessary to perform quantification. Because no stable isotope of butane is commercially available, it is essential to develop a new approach by an in situ generation of standards. To avoid the manipulation of a stable isotope-labelled gas, we have chosen to generate in situ an internal labelled standard gas (C(4)H(9)D) following the basis of the stoichiometric formation of butane by the reaction of deuterated water (D(2)O) with Grignard reagent butylmagnesium chloride (C(4)H(9)MgCl). This method allows a precise measurement of butane concentration and therefore, a full validation by accuracy profile was presented.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

PURPOSE: To use measurement by cycling power meters (Pmes) to evaluate the accuracy of commonly used models for estimating uphill cycling power (Pest). Experiments were designed to explore the influence of wind speed and steepness of climb on accuracy of Pest. The authors hypothesized that the random error in Pest would be largely influenced by the windy conditions, the bias would be diminished in steeper climbs, and windy conditions would induce larger bias in Pest. METHODS: Sixteen well-trained cyclists performed 15 uphill-cycling trials (range: length 1.3-6.3 km, slope 4.4-10.7%) in a random order. Trials included different riding position in a group (lead or follow) and different wind speeds. Pmes was quantified using a power meter, and Pest was calculated with a methodology used by journalists reporting on the Tour de France. RESULTS: Overall, the difference between Pmes and Pest was -0.95% (95%CI: -10.4%, +8.5%) for all trials and 0.24% (-6.1%, +6.6%) in conditions without wind (<2 m/s). The relationship between percent slope and the error between Pest and Pmes were considered trivial. CONCLUSIONS: Aerodynamic drag (affected by wind velocity and orientation, frontal area, drafting, and speed) is the most confounding factor. The mean estimated values are close to the power-output values measured by power meters, but the random error is between ±6% and ±10%. Moreover, at the power outputs (>400 W) produced by professional riders, this error is likely to be higher. This observation calls into question the validity of releasing individual values without reporting the range of random errors.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Softcatalà is a non-profit associationcreated more than 10 years ago to fightthe marginalisation of the Catalan languagein information and communicationtechnologies. It has led the localisationof many applications and thecreation of a website which allows itsusers to translate texts between Spanishand Catalan using an external closed-sourcetranslation engine. Recently,the closed-source translation back-endhas been replaced by a free/open-sourcesolution completely managed by Softcatalà: the Apertium machine translationplatform and the ScaleMT web serviceframework. Thanks to the opennessof the new solution, it is possibleto take advantage of the huge amount ofusers of the Softcatalà translation serviceto improve it, using a series ofmethods presented in this paper. In addition,a study of the translations requestedby the users has been carriedout, and it shows that the translationback-end change has not affected theusage patterns.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The continuous wavelet transform is obtained as a maximumentropy solution of the corresponding inverse problem. It is well knownthat although a signal can be reconstructed from its wavelet transform,the expansion is not unique due to the redundancy of continuous wavelets.Hence, the inverse problem has no unique solution. If we want to recognizeone solution as "optimal", then an appropriate decision criterion hasto be adopted. We show here that the continuous wavelet transform is an"optimal" solution in a maximum entropy sense.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Tässä diplomityössä tutkitaan paalutuskoneen stabiliteetti- elivakavuuslaskennan toteuttamista yleisesti käytetyn monikappaledynamiikan ohjelmiston avulla. Vakavuuslaskenta kuuluu olennaisena osana paalutuskoneen suunnitteluun ja siitä saadut tulokset asettavat rajat massoille, joita paalutuskone pystyy turvallisesti käsittelemään. Tutkittavana kohteena oli uudentyyppinen poraavapaalutuskone, josta saatiin myös todellista mittaustietoa työssä laaditun simulointimallin toimivuuden arvioimiseksi. Työssä kokeiltiin erityisesti ohjelmiston tarjoamia keinoja laskentaprosessin yksinkertaistamiseksi jasimulointimallin käytön helpottamiseksi. Koska simulointimalli haluttiin säilyttää mahdollisimman yksinkertaisena, porakoneen komponentit mallinnettiin jäykkinä. Mallin ratkaisussa käytettiin staattista ja kvasistaattista analyysia. Dynaamisten voimien vaikutus porakoneeseen otettiin mallissa huomioon lisäämällä massakeskipisteisiin vastaavat pistevoimat.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

PURPOSE: To prospectively evaluate the accuracy and reliability of "freehand" posttraumatic orbital wall reconstruction with AO (Arbeitsgemeinschaft Osteosynthese) titanium mesh plates by using computer-aided volumetric measurement of the bony orbits. METHODS: Bony orbital volume was measured in 12 patients from coronal CT scan slices using OsiriX Medical Image software. After defining the volumetric limits of the orbit, the segmentation of the bony orbital region of interest of each single slice was performed. At the end of the segmentation process, all regions of interest were grouped and the volume was computed. The same procedure was performed on both orbits, and thereafter the volume of the contralateral uninjured orbit was used as a control for comparison. RESULTS: In all patients, the volume data of the reconstructed orbit fitted that of the contralateral uninjured orbit with accuracy to within 1.85 cm3 (7%). CONCLUSIONS: This preliminary study has demonstrated that posttraumatic orbital wall reconstruction using "freehand" bending and placement of AO titanium mesh plates results in a high success rate in re-establishing preoperative bony volume, which closely approximates that of the contralateral uninjured orbit.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Introduction: The pharmaceutical aspects of drug administration in clinical trials receive poor consideration compared with the important attention devoted to the analytical and mathematical aspects of biological sample exploitation. During PK calculations, many researchers merely use for dose the nominal amount declared, overlooking the noticeable biases that may result in the assessment of PK parameters. The aim of this work was to evaluate the biases related to doses injected of a biosimilar drug in 2 Phase I clinical trials. Patients (or Materials) and Methods: In trial A, 12 healthy volunteers received different doses of a biosimilar of interferon beta-1a by either subcutaneous (SC) or intravenous (IV) injection. The doses were prepared by partially emptying 0.5-mL syringes supplied by the manufacturer (drop count procedure). In trial B, 12 healthy volunteers received 3 different formulations of the drug by IV injection (biosimilar without albumin [HSA], biosimilar with HSA and original brand [Rebif®]) and 2 different formulations as multiple SC injections (biosimilar HSA-free and original brand). In both trials, the actual dose administered was calculated as: D = C·V - losses. The product titer C was assessed by ELISA. The volume administered IV was assessed by weighting. Losses were evaluated by in vitro experiments. Finally, the binding of 125I-interferon to HSA was evaluated by counting the free and HSA complexed molecule fractions separated by gel filtration. Results: Interferon was not significantly adsorbed onto the lines used for its IV administration. In trial A, the titer was very close to the one declared (96 ± 7%). In trial B, it differed significantly (156 ± 10% for biosimilar with/without HSA and 123 ± 5% for original formulation). In trial A, the dose actually administered showed a large variability. The real injected volume could be biased up to 75% compared with the theoretical volume (for the lower dose administered [ie, 0.03 mL]). This was mainly attributed to a partial re-aspiration of the drug solution before withdrawing the syringe needle. A strict procedure was therefore applied in trial B to avoid these inaccuracies. Finally, in trial B, 125I-Interferon beta-1a binding to HSA appeared time dependent and slow, reaching 50% after 16-hour incubation, which is close to steady state reported for the comparator Rebif®. Conclusion: These practical examples (especially biases on actual titer and volume injected) illustrate that actual dose assessment deserves attention to ensure accuracy for estimates of clearance and distribution volume in the scientific literature and for registration purposes, especially for bioequivalence studies.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Verkkoon kytkettävien laitteiden määrä on lisääntynyt viime vuosina, joka luo tarpeen reitittimille ja niiden ominaisuuksille. On muodostunut uusi tarve laitteille, jotka voivat yhdistää erilaisia verkkoja toisiinsa. Tällaisen reitittimen rakentamiseen tarvitaan vakaa alusta. Tällaisella alustalla luodaan mahdollisuus kuormittaa järjestelmää ilman suuria ongelmia. Tällainen alusta on Open Platform, joka on suunniteltu tällaisille toiminnoille ja yhdessä oikeanlaisen verkkoratkaisun kanssa sitä voidaan käyttää sille suunnitellussa ympäristössä. Tämän diplomityön tarkoituksena on arvioida neljää eri reititysohjelmistoa ja kahta eri IP pinoa. Työssä käytetyt testit on suunniteltu arviointia varten ja niiden tarkoituksena on tuoda esille ohjelmistoissa esiintyvät viat ja ongelmat. Kaikki testit ovat samoja kaikille ohjelmille ja tehdään samassa ympäristössä. Testit analysoidaan niiden ajon jälkeen ja niiden tulosten avulla tehdään päätös mitä näistä ohjelmistoista tullaan käyttämään seuraavan sukupolven avoimella alustalla, joka tulee toimimaan Nokian Intelligent Service Nodessa. Tämä verkon laite toimii yhdyskäytävänäerilaisten verkkojen välillä.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Diplomityön ensimmäisessä vaiheessa tutkittiin hydraulisen kuristimen ominaisuuksia ja esiteltiin numeerisesti tehokas kuristinmalli käyttäenpolynomifunktiota virtauksen laminaarisen ja transitioalueen kuvaukseen. Puoliempiirisen mallin paremmuus tulee esille siinä, että kuristimen geometriatietoja ei tarvita laskettaessa virtausta paine-eron perusteella. Reaaliaikasimuloinnissa esiintyy kompromisseja tarkkuuden ja laskentanopeuden välillä. Tätä asiaa tutkittiin kahden virtausalueen kuristinmallilla. Transition paine-eron ja integrointiaika-askelen valinnan vaikutus tarkkuuteen ja laskentanopeuteen tutkittiin. Toisessa vaiheessa tutkittiin mahdollisimman hyvän liiketuntuman tuottamista liikealustalla ohjaussignaalia kehittämällä. Liikealustan liikeradan rajallisuudesta johtuen ohjauksessa on perinteisesti käytetty washout-suodatusta, joka erottelee simuloitavan järjestelmän kiihtyvyyssignaalista vain nopeatkiihtyvyydet. Tässä työssä tutkittiin hitaiden kiihtyvyyksien ottamista mukaan liikealustan ohjaukseen liikealustan liikeradan puitteissa. Tämä toteutettiin kuvaamalla hitaat kiihtyvyydet kallistamalla liikealustaa, jolloin käyttäjään kohdistuva voima saatiin kuvattua gravitaatiota hyväksi käyttäen.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Uusia keinoja kullan erottamiseksi malmista on etsitty viimeaikoina taloudellisista ja ympäristöllisistä syistä kautta maailman. Syanidointimenetelmä on hallinnut kullan talteenottoayli sata vuotta. Menetelmässä kulta liuotetaan laimeaan syanidiliuokseen, jostase otetaan talteen aktiivihiilen avulla. Syanidin käyttöä pyritään kuitenkin vähentämään sen myrkyllisyyden takia. Lisäksi nykyään louhitaan enenemässä määrin malmia, josta on hankala rikastaa kulta kustannustehokkaasti syanidia käyttäen. Kullan talteenottoa syanidi- ja kloridiliuoksesta on selvitetty kirjallisuuden avulla. Kullan kemiaan liuotuksen aikana on perehdytty ennen kullan talteenottoa aktiivihiilellä. Aktiivihiilen elinkaari kullan adsorbenttinaon käsitelty valmistuksesta hylkäämiseen mukaan lukien hiilen myrkyttyminen prosessissa ja regenerointi. Aktiivi-hiilen käyttäytyminen syanidi- ja kloridiliuoksessa on selvitetty erikseen. Kullan talteenottoa kuparipitoisista malmeista on käsitelty. Kullan talteenottoa kloridiliuoksesta aktiivihiiltä käyttäen on tutkittu kokeellisesti. Pääasialliset tutkimuskohteet ovat adsorption kinetiikka, kuparin vaikutus adsorptioon, aktiivihiilen vaikutus adsorptioonja adsorboituneiden metallien strippaus hiilestä selektiivisesti. Hapettavan stippauksen vaikutus kullan desorptioon hiilestä on tutkittu yksityiskohtaisesti. Kullan erotusmenetelmät kuparimalmista aktiivihiiltä käyttäen on selvitetty diplomityön tulosten pohjalta. Diplomityön keskeisten tulosten perusteella kulta ei välttämättä saostu aktiivihiilen pinnalle kloridiliuoksesta. Havainto varmistettiin ladattujen hiilipartikkelien pyyhkäisyelektronimikroskooppikuvista ja partikkeleille tehdyistä mikroanalyyseistä. Kullan pelkistyminen metalliseksi kullaksi aktiivihiilessä voitaneen välttää käyttämällä erittäin hapettavia olosuhteita. Aktiivihiili ilmeisesti hapettuu näissä olosuhteissa, mikä mahdollistaa kultakloridin adsorboitumisen hiileen.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Objective: to assess the diagnostic accuracy of different anthropometric markers in defining low aerobic fitness among adolescents. Methods: cross-sectional study on 2,331 boys and 2,366 girls aged 10 - 18 years. Body mass index (BMI) was measured using standardized methods; body fat (BF) was assessed by bioelectrical impedance. Low aerobic fitness was assessed by the 20-meter shuttle run using the FITNESSGRAMR criteria. Waist was measured in a subsample of 1,933 boys and 1,897 girls. Overweight, obesity and excess fat were defined according to the International Obesity Task Force (IOTF) or FITNESSGRAMR criteria. Results: 38.5% of boys and 46.5% of girls were considered as unfit according to the FITNESSGRAMR criteria. In boys, the area under the ROC curve (AUC) and 95% confidence interval were 66.7 (64.1 - 69.3), 67.1 (64.5 - 69.6) and 64.6 (61.9 - 67.2) for BMI, BF and waist, respectively (P<0.02). In girls, the values were 68.3 (65.9 - 70.8), 63.8 (61.3 - 66.3) and 65.9 (63.4 - 68.4), respectively (P<0.001). In boys, the sensitivity and specificity to diagnose low fitness were 13% and 99% for obesity (IOTF); 38% and 86% for overweight + obesity (IOTF); 28% and 94% for obesity (FITNESSGRAMR) and 42% and 81% for excess fat (FITNESSGRAMR). For girls, the values were 9% and 99% for obesity (IOTF); 33% and 82% for overweight + obesity (IOTF); 22% and 94% for obesity (FITNESSGRAMR) and 26% and 90% for excess fat (FITNESSGRAMR). Conclusions: BMI, not body fat or waist, should be used to define low aerobic fitness. The IOTF BMI cut-points to define obesity have a very low screening capacity and should not be used.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

OBJECTIVES: Resuscitation in severe head injury may be detrimental when given with hypotonic fluids. We evaluated the effects of lactated Ringer's solution (sodium 131 mmol/L, 277 mOsm/L) compared with hypertonic saline (sodium 268 mmol/L, 598 mOsm/L) in severely head-injured children over the first 3 days after injury. DESIGN: An open, randomized, and prospective study. SETTING: A 16-bed pediatric intensive care unit (ICU) (level III) at a university children's hospital. PATIENTS: A total of 35 consecutive children with head injury. INTERVENTIONS: Thirty-two children with Glasgow Coma Scores of <8 were randomly assigned to receive either lactated Ringer's solution (group 1) or hypertonic saline (group 2). Routine care was standardized, and included the following: head positioning at 30 degrees; normothermia (96.8 degrees to 98.6 degrees F [36 degrees to 37 degrees C]); analgesia and sedation with morphine (10 to 30 microg/kg/hr), midazolam (0.2 to 0.3 mg/kg/hr), and phenobarbital; volume-controlled ventilation (PaCO2 of 26.3 to 30 torr [3.5 to 4 kPa]); and optimal oxygenation (PaO2 of 90 to 105 torr [12 to 14 kPa], oxygen saturation of >92%, and hematocrit of >0.30). MEASUREMENTS AND MAIN RESULTS: Mean arterial pressure and intracranial pressure (ICP) were monitored continuously and documented hourly and at every intervention. The means of every 4-hr period were calculated and serum sodium concentrations were measured at the same time. An ICP of 15 mm Hg was treated with a predefined sequence of interventions, and complications were documented. There was no difference with respect to age, male/female ratio, or initial Glasgow Coma Score. In both groups, there was an inverse correlation between serum sodium concentration and ICP (group 1: r = -.13, r2 = .02, p < .03; group 2: r = -.29, r2 = .08, p < .001) that disappeared in group 1 and increased in group 2 (group 1: r = -.08, r2 = .01, NS; group 2: r = -.35, r2 =.12, p < .001). Correlation between serum sodium concentration and cerebral perfusion pressure (CPP) became significant in group 2 after 8 hrs of treatment (r = .2, r2 = .04, p = .002). Over time, ICP and CPP did not significantly differ between the groups. However, to keep ICP at <15 mm Hg, group 2 patients required significantly fewer interventions (p < .02). Group 1 patients received less sodium (8.0 +/- 4.5 vs. 11.5 +/- 5.0 mmol/kg/day, p = .05) and more fluid on day 1 (2850 +/- 1480 vs. 2180 +/- 770 mL/m2, p = .05). They also had a higher frequency of acute respiratory distress syndrome (four vs. 0 patients, p = .1) and more than two complications (six vs. 1 patient, p = .09). Group 2 patients had significantly shorter ICU stay times (11.6 +/- 6.1 vs. 8.0 +/- 2.4 days; p = .04) and shorter mechanical ventilation times (9.5 +/- 6.0 vs. 6.9 +/- 2.2 days; p = .1). The survival rate and duration of hospital stay were similar in both groups. CONCLUSIONS: Treatment of severe head injury with hypertonic saline is superior to that treatment with lactated Ringer's solution. An increase in serum sodium concentrations significantly correlates with lower ICP and higher CPP. Children treated with hypertonic saline require fewer interventions, have fewer complications, and stay a shorter time in the ICU.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Convective transport, both pure and combined with diffusion and reaction, can be observed in a wide range of physical and industrial applications, such as heat and mass transfer, crystal growth or biomechanics. The numerical approximation of this class of problemscan present substantial difficulties clue to regions of high gradients (steep fronts) of the solution, where generation of spurious oscillations or smearing should be precluded. This work is devoted to the development of an efficient numerical technique to deal with pure linear convection and convection-dominated problems in the frame-work of convection-diffusion-reaction systems. The particle transport method, developed in this study, is based on using rneshless numerical particles which carry out the solution along the characteristics defining the convective transport. The resolution of steep fronts of the solution is controlled by a special spacial adaptivity procedure. The serni-Lagrangian particle transport method uses an Eulerian fixed grid to represent the solution. In the case of convection-diffusion-reaction problems, the method is combined with diffusion and reaction solvers within an operator splitting approach. To transfer the solution from the particle set onto the grid, a fast monotone projection technique is designed. Our numerical results confirm that the method has a spacial accuracy of the second order and can be faster than typical grid-based methods of the same order; for pure linear convection problems the method demonstrates optimal linear complexity. The method works on structured and unstructured meshes, demonstrating a high-resolution property in the regions of steep fronts of the solution. Moreover, the particle transport method can be successfully used for the numerical simulation of the real-life problems in, for example, chemical engineering.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Crystal growth is an essential phase in crystallization kinetics. The rate of crystal growth provides significant information for the design and control of crystallization processes; nevertheless, obtaining accurate growth rate data is still challenging due to a number of factors that prevail in crystal growth. In industrial crystallization, crystals are generally grown from multi-componentand multi-particle solutions under complicated hydrodynamic conditions; thus, it is crucial to increase the general understanding of the growth kinetics in these systems. The aim of this work is to develop a model of the crystal growth rate from solution. An extensive literature review of crystal growth focuses on themodelling of growth kinetics and thermodynamics, and new measuring techniques that have been introduced in the field of crystallization. The growth of a singlecrystal is investigated in binary and ternary systems. The binary system consists of potassium dihydrogen phosphate (KDP, crystallizing solute) and water (solvent), and the ternary system includes KDP, water and an organic admixture. The studied admixtures, urea, ethanol and 1-propanol, are employed at relatively highconcentrations (of up to 5.0 molal). The influence of the admixtures on the solution thermodynamics is studied using the Pitzer activity coefficient model. Theprediction method of the ternary solubility in the studied systems is introduced and verified. The growth rate of the KDP (101) face in the studied systems aremeasured in the growth cell as a function of supersaturation, the admixture concentration, the solution velocity over a crystal and temperature. In addition, the surface morphology of the KDP (101) face is studied using ex situ atomic force microscopy (AFM). The crystal growth rate in the ternary systems is modelled on the basis of the two-step growth model that contains the Maxwell-Stefan (MS) equations and a surface-reaction model. This model is used together with measuredcrystal growth rate data to develop a new method for the evaluation of the model parameters. The validation of the model is justified with experiments. The crystal growth rate in an imperfectly mixed suspension crystallizer is investigatedusing computational fluid dynamics (CFD). A solid-liquid suspension flow that includes multi-sized particles is described by the multi-fluid model as well as by a standard k-epsilon turbulence model and an interface momentum transfer model. The local crystal growth rate is determined from calculated flow information in a diffusion-controlled crystal growth regime. The calculated results are evaluated experimentally.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Software engineering is criticized as not being engineering or 'well-developed' science at all. Software engineers seem not to know exactly how long their projects will last, what they will cost, and will the software work properly after release. Measurements have to be taken in software projects to improve this situation. It is of limited use to only collect metrics afterwards. The values of the relevant metrics have to be predicted, too. The predictions (i.e. estimates) form the basis for proper project management. One of the most painful problems in software projects is effort estimation. It has a clear and central effect on other project attributes like cost and schedule, and to product attributes like size and quality. Effort estimation can be used for several purposes. In this thesis only the effort estimation in software projects for project management purposes is discussed. There is a short introduction to the measurement issues, and some metrics relevantin estimation context are presented. Effort estimation methods are covered quite broadly. The main new contribution in this thesis is the new estimation model that has been created. It takes use of the basic concepts of Function Point Analysis, but avoids the problems and pitfalls found in the method. It is relativelyeasy to use and learn. Effort estimation accuracy has significantly improved after taking this model into use. A major innovation related to the new estimationmodel is the identified need for hierarchical software size measurement. The author of this thesis has developed a three level solution for the estimation model. All currently used size metrics are static in nature, but this new proposed metric is dynamic. It takes use of the increased understanding of the nature of the work as specification and design work proceeds. It thus 'grows up' along with software projects. The effort estimation model development is not possible without gathering and analyzing history data. However, there are many problems with data in software engineering. A major roadblock is the amount and quality of data available. This thesis shows some useful techniques that have been successful in gathering and analyzing the data needed. An estimation process is needed to ensure that methods are used in a proper way, estimates are stored, reported and analyzed properly, and they are used for project management activities. A higher mechanism called measurement framework is also introduced shortly. The purpose of the framework is to define and maintain a measurement or estimationprocess. Without a proper framework, the estimation capability of an organization declines. It requires effort even to maintain an achieved level of estimationaccuracy. Estimation results in several successive releases are analyzed. It isclearly seen that the new estimation model works and the estimation improvementactions have been successful. The calibration of the hierarchical model is a critical activity. An example is shown to shed more light on the calibration and the model itself. There are also remarks about the sensitivity of the model. Finally, an example of usage is shown.