Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2013.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 107-109).
Air ...traffic growth in the U.S. has led to runway capacity constraints in the air transportation network. There has been limited new construction of runways due to land availability. One approach to increase capacity of existing runways is to reduce inter-arrival separations during the final approach phase of flight. This study evaluates two major elements influencing runway capacity; runway occupancy and wake vortex separation, and under what conditions each becomes a constraint to runway capacity. A detailed analysis of runway occupancy time measurements and wake vortex separation measurements is performed for Boston, Philadelphia, New York La Guardia, and Newark airports based on Airport Surface Detection Equipment Model-X (ASDE-X) aircraft surveillance data. The findings of this study indicate that runway occupancy does not necessary scale with aircraft size. Small aircraft often occupy the runway as long as large aircraft, which limits the potential for reduced separations behind small aircraft. The results also indicate that high-speed runway exits can make a significant difference in runway occupancy. Runways equipped with high-speed exits have lower runway occupancy times than runways equipped with standard 90-degree exits. Comparison of runway occupancy times in Visual Meteorological Conditions (VMC) and Instrument Meteorological Conditions (IMC) suggest no significant difference between the two weather conditions. Wake vortex separation measurements show that aircraft pairs with small lead aircraft receive longer separation buffers than other aircraft pairs, and airports with more runways implement longer separation buffers. The comparison of landing time intervals and runway occupancy illustrates that wake vortex separation requirements limit runway capacity when heavy or Boeing 757 is the lead aircraft. Lastly, this study evaluates the runway capacity benefits of reduced wake separation requirements for the aircraft re-categorization (RECAT) program. The results estimate an 8.2-8.3% increase in runway capacity at Philadelphia and at Newark, a 7.8% increase at Boston, and a 5.1% increase at La Guardia. The magnitude of benefits strongly depends on how the local traffic mix looks like.
by Tamas Kolos-Lakatos.
S.M.
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2017.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 172-178).
The ...air transportation industry continues to grow worldwide, but demand is often limited by available airspace and airport capacity. This thesis focuses on evaluating new air traffic procedures: specifically, new and emerging wake turbulence separation rules that could potentially increase runway capacity based on today's knowledge of wake vortex turbulence and technological capabilities. While legacy wake separation rules establish aircraft-classes based on weight of aircraft, these new separation rules can define separation standards by considering other aircraft parameters and dynamic wind conditions. A fast-time runway system model is developed for studying these wake separation rules, using Monte-Carlo simulations, to provide accurate and realistic runway capacity estimates based on the randomness of arrival and departure operations. A total of nine new proposed wake separation rules are analyzed in detail, which include both distance-based and time-based methods, as well as static and dynamic concepts. Seven of the busiest and most delayed U.S. airports are selected as case studies for the illustration of runway capacity benefits enabled by these new wake separation rules: Boston (BOS), New York J.F. Kennedy (JFK), New York LaGuardia (LGA), Newark (EWR), San Francisco (SFO), Los Angeles (LAX), and Chicago O'Hare (ORD). For a detailed capacity analysis, the new wake separation rules are tested under the most constraining runway configurations at each of these airports. The results indicate that increasing the number of aircraft wake categories can increase runway capacity, but the added benefits become smaller with each new category added. A five-or six-category wake separation system can capture most of the runway capacity that can be achieved with a static pair-wise system. Additionally, shifting wake category boundaries between airports as a function of local fleet mix can provide additional runway capacity benefits, meaning that airport specific wake separation rules can increase capacity over a universal separation rule system. Among the new wake separation rules, the results indicate that reducing wake separations further from current minimum separations (separation values of 2NM or less) can shift the operational bottleneck from the approach path to the runway, as runway occupancy time becomes the limiting factor for inter-arrival separations. The findings from the time-based separation rule demonstrate that switching from distance-based separations to time-based separations in strong headwind conditions can recover significant lost capacity. Time-based separation rules can be of great value to increase operational reliability and capacity predictability at airports in all weather conditions. Moreover, the results also indicate that a reduction in minimum separations enabled by dynamic wind and aircraft information can offer marginal runway capacity benefits over the capacity enabled by static pair-wise wake separations, as more and more aircraft pairs become limited by runway occupancy time. Therefore, a joint effort is needed for reducing both wake separations and runway occupancy in order to accommodate future air traffic demand.
by Tamas Kolos-Lakatos.
Ph. D.
A non-optical, pulsed reset technique for use in charge sensitive preamplifiers with Si(Li) X-ray semiconductor detectors of conventional polarity is described. The phenomenon of impact ionization in ...the field effect transistor is used for charge restoration. The process is controlled via the detector capacitance. The method needs no extra components in the input circuitry. No significant resolution degradation can be detected up to 600 kcps Mn K intensity if following the 5 μs resetting pulse the signal processor is inhibited for 50 μs.
Ramet distribution, leaf morphometry and elemental composition of Caltha palustris L. were studied along a hydrologic gradient in Nyárias marsh, N. E. Hungary, to identify patterns associated with ...water depth. Water-table height was linearly correlated with distance over most of the plant's distribution range. Caltha ramets were not dispersed uniformly but appeared in an aggregated pattern of a 12m scale. However, no clear relationship was found between water depth and the density of ramets, leaf number per ramet, aspects of plant performance (leaf blade and petiole dry weight), water status (water content of leaf parts), or leaf morphometry (lamina length and breadth, petiole length). Leaf size decreased towards both ends of the transect, and was highest at intermediate position. Contrastingly, foliar concentrations of several elements (e.g. Na, Mn, Cu) and especially the Fe: Mn ratio were strongly correlated with water-table height. Principal components analysis revealed two groups of elements: one discriminating between the lamina and the petiole but uncorrelated with the gradient (Ca, S, Fe, P, AI, K), and another not discriminating but positively correlated with the gradient (Na, Mn, Mg).
The complex patterns of Caltha population traits in Nyárias demonstrate the ecologic importance of small-scale spatial (i.e. microtopographic) differences in wetlands. Besides water depth and duration per se, biotic factors such as gradients of standing crop, species richness or competition intensity may have intricate effects on single populations. Foliar Fe: Mn ratios, however, seem to be directly determined by water-table height and associated soil chemistry, thus can be a subtile indicator of wetland water conditions.
AIM： To assess the combined effect of disease phenotype, smoking and medical therapy steroid, azathioprine （AZA）, AZA/biological therapy on the probability of disease behavior change in a Caucasian ...cohort of patients with Crohn＇s disease （CD）. METHODS： Three hundred and forty well-characterized, unrelated, consecutive CD patients were analyzed （M/F： 155/185, duration： 9.4 ± 7.5 years） with a complete clinical follow-up. Medical records including disease phenotype according to the Montreal classification, extraintestinal manifestations, use of medications and surgical events were analyzed retrospectively. Patients were interviewed on their smoking habits at the time of diagnosis and during the regular follow-up visits. RESULTS： A change in disease behavior was observed in 30.8% of patients with an initially non-stricturing, non-penetrating disease behavior after a mean disease duration of 9.0 ± 7.2 years. In a logistic regression analysis corrected for disease duration, perianal disease, smoking, steroid use, early AZA or AZA/ biological therapy use were independent predictors of disease behavior change. In a subsequent Kaplan-Meier survival analysis and a proportional Cox regression analysis, disease location （P = 0.001）, presence of perianal disease （P 〈 0.001）, prior steroid use （P = 0.006）, early AZA （P = 0.005） or AZA/biological therapy （P = 0.002）, or smoking （P = 0.032） were independent predictors of disease behavior change. CONCLUSION： Our data suggest that perianal disease, small bowel disease, smoking, prior steroid use, early AZA or AZA/biological therapy are all predictors of disease behavior change in CD patients.
AIM:To assess the endoscopic activity before and after a one-year period of biological therapy and to evaluate the frequency of relapses and need for retreatment after stopping the biologicals in ...patients with Crohn’s disease(CD)and ulcerative colitis(UC).METHODS:The data from 41 patients with CD and 22 patients with UC were assessed.Twenty-four CD patients received infliximab,and 17 received adalimumab.The endoscopic severity of CD was quantified with the simplified endoscopic activity score for Crohn’s disease in CD and with the Mayo endoscopic subscore in UC.RESULTS:Mucosal healing was achieved in 23 CD and7 UC patients.Biological therapy had to be restarted in78%of patients achieving complete mucosal healing with CD and in 100%of patients with UC.Neither clinical remission nor mucosal healing was associated with the time to restarting the biological therapy in either CD or UC.CONCLUSION:Mucosal healing did not predict sustained clinical remission in patients in whom the biological therapies had been stopped.
Charge pulse restorer for resistor feedback preamplifiers Hegyesi, Gyula; Lakatos, Tamas
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/1995, Letnik:
356, Številka:
2
Journal Article
Recenzirano
A simple circuit for cancelling the main pole of traditional resistor feedback preamplifier output signals has been designed. The resultant waveform is a series of step functions equivalent to the ...output of a pulsed feedback preamplifier. The advantage of such a preamplifier output signal is that its quantized samples can directly be processed by certain digital signal processors.
AIM： To determine the prevalence of a new set ot anti-glycan and anti-outer membrane protein （anti- OMP） antibodies in a Hungarian cohort of adult Celiac disease （CD） patients. METHODS： 190 ...consecutive CD patients M/F： 71/119, age：39.9 （SD：14.1） years, 100 healthy, and 48 gastrointestinal controls were tested for glycan anti-Saccharomyces cerevisiae （gASCA）, anti-laminaribioside （ALCA）, anti-chitobioside, anti-mannobioside, anti-OMP antibodies and major NOD2/CARD15 mutations. Thirty out of 82 CD patients enrolled at the time of diagnosis were re-evaluated for the same antibodies after longstanding gluten-free diet （GFD）. RESULTS： 65.9% of the CD patients were positive for at least one of the tested antibodies at the time of the diagnosis. Except anti-OMP and ALCA, antimicrobial antibodies were exclusively seen in untreated CD; however, the overall sensitivity was low. Any glycan positivity （LR＋： 3.13; 95% CI： 2.08-4.73） was associated with an increased likelihood ratio for diagnosing CD. Significant correlation was found between the levels of anti-glycan and anti-endomysial or anti-transglutaminase antibodies. Anti-glycan positivity was lost after longstanding GFD. Anti-glycan antibody titers were associated with symptoms at presentation, but not the presence of NOD2/CARD15 mutations. Patients with severe malabsorption more frequently had multiple antibodies at diagnosis （P = 0.019）. CONCLUSION： The presence of anti-glycan antibodies in CD seems to be secondary to the impaired small bowel mucosa which can lead to increased antigen presentation. Furthermore, anti-glycan positivity may be considered an additional marker of CD and dietary adherence.
The incidence and prevalence of ulcerative colitis (UC) varies geographically. The risk of colorectal cancer (CRC) and possibly some other malignancies is increased among patients with UC. It is ...still debated if patients with UC are at a greater risk of dying compared with the general population. Our aim was to describe the epidemiology and mortality of the Hungarian UC population from 2010 to 2016 and to analyze the associated malignancies with a special focus on CRC.
This is an observational, descriptive, epidemiological study based on the National Health Insurance Fund social security databases from 2010 to 2016. All adult patients who had at least two events in outpatient care or at least two medication prescriptions, or at least one inpatient event with UC diagnosis were analyzed. Malignancies and CRC were defined using ICD-10 codes. We also evaluated the survival of patients suffering from UC compared with the general population using a 3 to 1 matched random sample (age, gender, geography) from the full population of Hungary.
We found the annual prevalence of UC 0.24-0.34%. The incidence in 2015 was 21.7/100 000 inhabitants. Annual mortality rate was 0.019-0.023%. In this subpopulation, CRC was the most common cancer, followed by non-melanotic skin and prostate cancer. 8.5% of the UC incident subpopulation was diagnosed with CRC. 470 (33%) of the CRC patients died during the course of the study (25% of all deaths were due to CRC), the median survival was 9.6 years. UC patients had significantly worse survival than their matched controls (HR = 1.65, 95% CI: 1.56-1.75).
This is the first population-based study from Eastern Europe to estimate the different malignancies and mortality data amongst Hungarian ulcerative colitis patients. Our results revealed a significantly worse survival of patients suffering from UC compared to the general population.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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