878 research outputs found
Preliminary design of a multi-spacecraft mission to investigate solar system
No full textThis paper discusses a mission design concept that uses high-power solar electric propulsion (SEP) to re-direct one asteroid into the path of another, generating a low-velocity impact as a means of studying solar system evolution. In order to validate existing models and gain further insight in the processes involved, a multispacecraft approach is proposed. This concept involves stationing a spacecraft at each asteroid, using them to achieve precise orbits of both asteroids, and one of the spacecraft with high-power SEP to deflect its asteroid into a low-velocity collision with the other. This study will show that it is possible to achieve asteroid collisions with a relative velocity below 10 km/s, allowing direct observations to study solar system dynamics.AAS 15-765Astrodynamics & Space Mission
Endothelial Cell–Specific Deficiency of Ang II Type 1a Receptors Attenuates Ang II–Induced Ascending Aortic Aneurysms in LDL Receptor <sup>−/−</sup> Mice
No full text
Rationale:
Human studies and mouse models have provided evidence for angiotensin II (Ang II)–based mechanisms as an underlying cause of aneurysms localized to the ascending aorta. In agreement with this associative evidence, we have published recently that Ang II infusion induces aneurysmal pathology in the ascending aorta.
Objective:
The aim of this study was to define the role of angiotensin II type 1a (AT
1a
) receptors and their cellular location in Ang II–induced ascending aortic aneurysms (AAs).
Methods and Results:
Male LDL receptor
−/−
mice were fed a saturated fat–enriched diet for 1 week before osmotic mini-pump implantation and infused with either saline or Ang II (1000 ng/kg per minute) for 28 days. Intimal surface areas of ascending aortas were measured to quantify ascending AAs. Whole body AT
1a
receptor deficiency ablated Ang II–induced ascending AAs (
P
<0.001). To determine the role of AT
1a
receptors on leukocytes, LDL receptor
−/−
×AT
1a
receptor
+/+
or AT
1a
receptor
−/−
mice were irradiated and repopulated with bone marrow–derived cells isolated from either AT
1a
receptor
+/+
or AT
1a
receptor
−/−
mice. Deficiency of AT
1a
receptors in bone marrow–derived cells had no effect on Ang II–induced ascending AAs. To determine the role of AT
1a
receptors on vascular wall cells, we developed AT
1a
receptor floxed mice with depletion on either smooth muscle or endothelial cells using Cre driven by either SM22 or Tek, respectively. AT
1a
receptor deletion in smooth muscle cells had no effect on ascending AAs. In contrast, endothelial-specific depletion attenuated this pathology.
Conclusions:
Ang II infusion promotes aneurysms in the ascending aorta via stimulation of AT
1a
receptors that are expressed on endothelial cells.
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AAS „BALTA” property insurance rewards optimization
No full textBakalaura darbā „AAS „BALTA” mantiskās apdrošināšanas atlīdzību optimizācija” tiek apskatīta apdrošināšanas nozares vēsture, attīstība un tās produkts, apdrošināšanas nozares nozīme Latvijas ekonomikā, tai saistošā tiesiskā bāze un uzdevumi, analizēti galvenie apdrošināšanas tirgus dalībnieki un apdrošināšanas pakalpojumu veidi, sniegts ieskats AAS „BALTA” darbībā, raksturots mantiskās apdrošināšanas produkts un atlīdzību process. Kā arī veikts salīdzinājums starp Latvijas apdrošināšanas tirgus vadošajām apdrošināšanas sabiedrībām mantiskajā apdrošināšanā, sniegti secinājumi un priekšlikumi AAS „BALTA” mantiskās apdrošināšanas atlīdzību uzlabošanai.
Pētījuma periods ir 2009.-2011.gads.
Bakalaura darba apjoms ir 64 lapas. Tas sastāv no 4 nodaļām, kurās ietvertas 8 tabulas, 8 diagrammas, 5 shēmas.The theme of the paper is „AAS „BALTA” property insurance rewards optimization”. Author inspects and describes activities of AAS “BALTA”, history of insurance industry, development of it and its products, the importance of insurance industry for economy of Latvia, its compulsory legal regulations and objectives. Author has also analyzed main competitors of the insurance market and insurance products. Author has given insight of AAS “BALTA” activities, he has also described property insurance product and reward for this product. In the research part of the work author has made comparison of leading property insurance market competitors of Latvia’s insurance market and given his conclusion for it as well as proposals for making the processes of rewards for AAS “BALTA” property insurance better.
Period for the research is from year 2009 up to year 2011.
The content of the work is revealed in 64 pages. The paper consists of four parts, which includes 8 tables, 8 diagrams, 5 illustrations
AAS "Balta" analysis of operations
No full textLatvijas apdrošināšanas tirgū ir apdrošināšanas kompāniju pārblīvējums, kā rezultātā ir augsta konkurence un daļa no vadošajiem apdrošinātājiem strādā ar zaudējumiem.Bakalaura darba mērķis ir, pamatojoties uz AAS “BALTA” un vadošo Latvijas apdrošinātāju darbības datu analīzes pamata, identificēt AAS “BALTA” zaudējumu nesošos posmus un izstrādāt priekšlikumus to novēršanai. Lai sasniegtu darba mērķi, tiek pētīta Latvijas likumdošana, analizēta AAS “BALTA” struktūra, riska vadība un administratīvo izdevumu sadaļa. Autors secina, ka AAS “BALTA” pilnveidojot struktūru, investējot IT un pārskatot darbinieku darba uzdevumus var sasniegt peļņu, nemainot pakalpojuma izcenojumus.Insurance company clutter in the Latvian marketplace creates even more competitive environment and some part of insurers work with losses. Bachelor's work is based on the AAS "BALTA" and leading Latvian insurers business data analysis, which helpts to identify AAS "BALTA" loss-making stages and develop proposals for it’s elimination. In order to achieve the objective, author has looked deeper into Latvian legislation, analyzed AAS "BALTA" structure, risk management and administrative expenses section. The author concludes that AAS "BALTA" by improving the structure, investing in IT and reviewing employee work objectives can achieve profits without changing service pricing
New perspectives on the Italia tragedy and Umberto Nobile
No full textSeventy-seven years ago a tragedy took place in the Norwegian Arctic which shook the international community–especially Norwegians–and led to the public condemnation of the Italian explorer and airship builder Umberto Nobile. Steinar Aas, historian and author of a book on Nobile, has perused a trove of “new” material recently donated to the Norwegian Polar Institute and the Polar Museum in Tromsø, Norway. In this (unreviewed) piece, Aas explains why he finds the new collection a fascinating subject for further research
Applicability of evolutionary algorithms for orbit optimization in the strongly perturbed environment of the 2001 SN263 triple asteroid system
No full textThe ASTER mission under study by the Brazilian National Institute for Space Research would be the first to explore a triple asteroid system. To find orbits stable in such a perturbed environment, an orbit propagation and optimization programme has been written, which makes use of Evolutionary evolution algorithms. The programme written proves sufficient to identify suitable solutions for several use cases based on various mission phases and scenarios. The solar radiation pressure has been identified as a critical perturbation that prevents the existence of solutions in some scenarios, and often drives existing solutions towards terminator orbits.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Astrodynamics & Space Mission
ERGO Latvia AAS Brand Identification activities at 2007
No full textDarba “„ERGO Latvija” AAS zīmola atpazīstamību veicinošas aktivitātes (2007)”
teorētiskajā daĜā tika apskatīts: zīmols - tā rašanās, veidošana, mainīšana, uzlabošana un
vērtība, kā arī produkta un korporatīvais zīmols; integrēto mārketinga komunikāciju
veidošana – to būtība un mērėi, labdarība un sponsorēšana, uzĦēmuma tēla veidošanas
komunikācija, kā arī reklāma, tās mērėi, efektivitāte un veidi.
Darba ietvaros tika izvirzīta hipotēze – „ERGO Latvija” AAS 2007.gadā veiktās
aktivitātes nav veicinājušas zīmola atpazīstamību.
Lai gūtu apstiprinājumu vai arī apgāztu darbā izvirzīto hipotēzi, praktiskajā daĜā tika
apskatīts uzĦēmums "ERGO Latvija" AAS un tā 2007.gadā veiktās aktivitātes zīmola
atpazīstamības veicināšanai.
Kā pētniecības metodes, darba pētnieciskajā daĜā, tika izmantota tiešā anketēšana, ar
kuras palīdzību tika aptaujāti 200 respondenti un fokusa grupas diskusija, uz kuru autore
aicināja 8 cilvēkus, kuri atbilst „ERGO Latvija” AAS mērėauditorijai.
Apkopojot iegūto informāciju un ar pētniecības metodēm iegūtos datus, tika secināts,
ka „ERGO Latvija” AAS 2007.gadā veiktās aktivitātes ir bijušas nepietiekamas un to
izvietojums nepārdomāts, kā rezultātā sabiedrības zīmola atpazīstamību tās nav veicinājušas.
Tādējādi autore secina, ka darbā izvirzītā hipotēze ir apstiprinājusies.The work „The brand promotion activities of „ERGO Latvija” AAS (2007)”
describes: brand, its arise, building, changeing and worth; how to form integrated
marketing communications, their essence, aims as well as charity and sponsorship;
essence, aims, efectivity and variation of advertisment.
The hypothesis of the work is: „ERGO Latvija” AAS activities did not promote
its brand recognition.
Author choosed the direct mediatizing and focus group discussion as the most
suitable research methods. The 200 respondents were polled by mediatizing and 8
persons were invited to the focus group discussion.the results of poll showed that the
anwer to investigative question is positive.
Collecting the coughed information and results of the research methods, author
find that the hypothesis of the work corroborated
The reinforcement effects of PVA, PE, and steel fibers on AAS material
No full textThis paper employs PVA, PE, steel fibers, as well as the hybrids of two of the three fibers to reinforce alkali-activated slag (AAS) material, aiming to prepare strain-hardening and clinker-free composites. The flexural strength, compressive strength, uniaxial tensile performance of the composites and bond behavior between fibers and the matrix were tested to clarify the reinforcement effects of different fibers on the matrix. Strain-hardening AAS materials are obtained with compressive strengths of 116 MPa − 137 MPa (with fibers contributions of 17%−38%) and strain capacities over 0.8% at 60 d. The results indicate that there are several kinds of reinforcement effects of fibers on the matrix, namely bridging effect, lapping effect (for steel fibers), synergetic effect (for hybrid fibers) and static effect (for flexible fibers). Deterioration of PVA and PE fibers are found, indicating that these two fibers have poor adaptability in AAS material with a high alkalinity. This paper specially distinguishes the difference of the crack numbers during the strain-hardening stage only with the ones during the whole period including the following strain-softening stage. A new relationship is established between the crack numbers and the strain-stress curves, which provides a more reasonable way to characterize the strain-hardening property of fiber-reinforced composites.Materials and Environmen
AAS BALTA Physical property insurance product incriase of competitiveness
No full textBakalaura darba „AAS BALTA Fizisko personu īpašuma apdrošināšanas produkta konkurētspējas paaugstināšana” galvenais mērķis ir izstrādāt priekšlikumus AAS BALTA piedāvātā produkta pilnveidošanai, konkurētspējas paaugstināšanai.
Mērķa sasniegšanai autore ir izvirzījusi sekojošus uzdevumus – noteikt apdrošināšanas būtību, tās mērķus, funkcijas un pamatprincipus, apskatīt Latvijas apdrošināšanas nozari regulējošos normatīvos tiesību aktus, noskaidrot apdrošināšanas nozares vietu Latvijas ekonomikā, apkopot un analizēt informāciju par Latvijas nedzīvības apdrošināšanas tirgu un tā dalībniekiem, kā arī noteikt AAS BALTA produkta priekšrocības, trūkumus un konkurētspēju attiecībā pret trijām autores izvēlētajām apdrošināšanas akciju sabiedrībām.
Pētījuma periods ir 2005. – 2012.gads.
Bakalaura darba apjoms ir 61 lapas. Tas sastāv no 3 nodaļām, kurās ietvertas 15 tabulas, 3 attēli un 37 bibliogrāfiskie avoti.Main goal of bachelor thesis “AAS Balta Personal property insurance products increase of competitiveness’’ is to give proposals for AAS Balta products to improve the competitiveness.
Author has specified tasks to reach the goal – determine the insurance essence, its objectives, functions and principles, explore Latvian insurance industry regulatory laws, find out place of the insurance industry in the Latvian economy, compile and analyze information about Latvian non-life insurance market and it’s participants, as well as define AAS Balta products strengths, weakness and competitive against the three authors selected joint-stock insurance companies.
The study period is from 2005th to 2012th.
Bachelor thesis contains form 61 pages, that includes 15 tables, 3 illustrations and 37 bibliographic sources
Impact of Electric Taxi Systems on Airport Apron Operations and Gate Congestion at AAS
No full textGrowth in air traffic demand and increasing attention for environmental impact of the air travel industry and airports has spurred the innovation of the Electric Taxi System (ETS). The ETS incorporates an electric motor in the main or nose landing gear of an aircraft, powered by the auxiliary power unit (APU) of the aircraft. The system allows the aircraft to maneuver and taxi without the use of its main engines or a tow truck. Thereby, the ETS reduces fuel usage and the environmental impact during the taxi phase of flights. Additionally, the system aims to increase the gate pushback efficiency. The ETS eliminates the need for a tow truck during the pushback process as it allows for autonomous pushbacks. The studies performed on existing ETSs (the EGTS and theWheelTug systems) indicate that time can be saved with autonomous pushbacks using the ETS. KLM Royal Dutch Airlines and Amsterdam Airport Schiphol (AAS) have instigated research to investigate the impact and potential benefits of the implementation of the ETS. This Msc. thesis research work continues the exploration of the ETS’s impact at AAS by posing the following research question: What opportunities does the ETS offer for gate capacity and buffer utilization optimization, and what is the value of the impact of the ETS on apron operations at Amsterdam Airport Schiphol? Thus, the research attempts to draw light on the value of the ETS for operations in the apron environment. With increasing air traffic demand, the gate capacity at Schiphol Airport is nearing its maximum during the airport’s peak hours. Therefore, the potential gate capacity enhancement procedures enabled by the ETS are explored in detail in this research. Additionally, the value of the ETS for the overall apron environment is investigated. The reduction in the need for tow trucks due to the ETS implementation also provides benefits for the apron environment. The ETS presents the possibility for of two gate usage optimization concepts to be implemented more widely,namely; the dispatch towing concept and the pit stop concept. The gate planningmodels designed in this research explore the potential of the implementation of the pit stop and dispatch towing concepts at AAS. Initially, a gate planning model is designed to graphically present the narrow body gate and buffer plan in gantt chart format. In doing so the gate and buffer planning schedule for the busiest day at AAS in 2014 is visualized. The pit stop and dispatch towing concepts are then applied to the schedule where possible. From the visualization of the gate plans with and without the ETS enabled concepts, it can be concluded that the pit stop concept increases gate capacity at AAS by approximately six additionally aircraft on the busiest day at the airport in 2014. Furthermore, the dipatch towing concept increases gate planning efficiency and reduces ground arrival delays for six arriving aircraft on the busiest day at the airport in 2014. The gate planning model is subsequently expanded in order to explore the effect of increased traffic and delays on the gate planning at AAS, and the usage of pit stops and dispatch towing to help increase gate capacity and solve delay conflicts, respectively. From the extended model it becomes apparent that should the number of peak hour flights at AAS increase by 10%, and average of 25% of the additional flights can be scheduled at a gate using the pit stop concept. Should the number of peak hour flights double, an average of 8.8% of the additional peak hour flights (corresponding to 12 flights) can be scheduled using the pit stop concept. Furthermore, the model shows that, between 10% and 12% of the ground delays caused by delayed peak hour flights at the gates can be solved through the implementation of dispatch towing. This results in an average of 17.2minutes saved for nearly 50% of the arriving delayed flights. The gate planning models have indicated the potential of the pit stop and dispatch towing concepts enabled by the ETS for gate planning efficiency and capacity at AAS. However, the implementation of the ETS influences many key performance indicators (KPIs) of the apron area. In order to explore the value of the ETS on the apron area, a value model is developed. The value model is based on the value operations methodology (VOM). The value model qualitative assessment indicates that the ETS can enhance the safety, capacity, and efficiency of the airport apron environment, while reducing the costs and environmental impact of the apron area operations. The results of the models and the research performed can be further analyzed and developed by KLM and AAS in order to assist in the development of electric taxi systems and, eventually, enhance their competitive position within the aviation industry.Air Transport & Operations (ATO)Aerospace Engineerin
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