1,085 research outputs found
Original Poems by Horace L. Trim, Musician of Prescott Post No. 1 G.A.R. Providence, R.I.
No full textScanned from the collection of Ms. Linda Graf of Islesboro, Maine. Ms. Graf found the book in the attic of a home her family purchased in Islesboro that was originally owned by a family with the last name of Trim. The author is thought to be the same person who is credited for writing some of the original lyrics to Taps.https://digitalmaine.com/books/1054/thumbnail.jp
Trim17, novel E3 ubiquitin-ligase, initiates neuronal apoptosis
No full textAccumulating data indicate that the ubiquitin-proteasome system controls apoptosis by regulating the level and the function of key regulatory proteins. In this study, we identified Trim17, a member of the TRIM/RBCC protein family, as one of the critical E3 ubiquitin ligases involved in the control of neuronal apoptosis upstream of mitochondria. We show that expression of Trim17 is increased both at the mRNA and protein level in several in vitro models of transcription-dependent neuronal apoptosis. Expression of Trim17 is controlled by the PI3K/Akt/GSK3 pathway in cerebellar granule neurons (CGN). Moreover, the Trim17 protein is expressed in vivo, in apoptotic neurons that naturally die during post-natal cerebellar development. Overexpression of active Trim17 in primary CGN was sufficient to induce the intrinsic pathway of apoptosis in survival conditions. This pro-apoptotic effect was abolished in Bax(-/-) neurons and depended on the E3 activity of Trim17 conferred by its RING domain. Furthermore, knock-down of endogenous Trim17 and overexpression of dominant-negative mutants of Trim17 blocked trophic factor withdrawal-induced apoptosis both in CGN and in sympathetic neurons. Collectively, our data are the first to assign a cellular function to Trim17 by showing that its E3 activity is both necessary and sufficient for the initiation of neuronal apoptosis. Cell Death and Differentiation (2010) 17, 1928-1941; doi: 10.1038/cdd.2010.73; published online 18 June 201
Finding trim points of the ICE model using interval analysis
No full textIn this work interval analysis is applied to the thirteen control effector Innovative Control Effectors model to find its trim set. The method to find trim states is based on interval box consistency. At low speed the method is capable of finding interval enclosures of single trim points with a high accuracy if the minimum number of required control effectors is used. At higher speeds the found accelerations are larger. When looking for a full trim set the method finds continuous bounds on the control effectors for the entire input range in one run. This is a good demonstration of the advantages that interval analysis has over conventional methods that generally can only find one trim point at a time. The found bounds are a maximum of 1 deg wide for each control effector, but despite this the remaining accelerations can be up to 0.5 m/s^2 for linear accelerations and up to 10 deg/s^2 for rotational accelerations. Because of these large accelerations the found solutions are not acceptable as trim conditions. On the other hand the potential that interval analysis has as a trimming method is demonstrated, since continuous bounds on trim sets have been found in a single run. This is a feat that no other trimming method has yet accomplished. Further research is needed to exploit the full potential of interval trim methods so that the results can be used for other purposes such as flight envelope prediction.Aerospace Engineerin
Visualizing solutions of the circular restricted three-body problem
No full textThe stability of a satellite near the Lagrange points is studied in a Circular Restricted Three-Body Problem (CR3BP). The Runge Kutta method is used to trace out the orbital path of the satellite over a period of time. Various initial positions near the Lagrange points and velocities are used to produce various paths the satellite can take. The primary paths focused are on horseshoe paths.
Horseshoe orbits are shown to be sometimes stable and sometimes chaotic.M.S.Includes bibliographical references (p. 40)by Nkosi Nathan Tri
A Grey-box model approach using noon report data for trim optimization
No full textTrim optimization improves the energy efficiency of ships, thus reducing operational costs and emissions; however, trim tables are only available for a limited number of ships. There is thus a desire to develop additional, more accurate trim tables without the need for expensive model testing. The objective of this research was to develop a method to decrease fuel consumption by trim optimization, by a dynamic shaft power estimation model based on available operational data. A method that uses noon report data and a grey-box modelling approach is proposed. The grey box model consists of a multi-layer feedforward neural network to estimate the required shaft power, using operational parameters and an initial estimate of the required shaft power. A case study is presented for a modern chemical tanker and sea trials have been conducted to validate the results. The method provides correct trim advice for full load conditions; however, the magnitude of the effect is smaller compared to sea trial results. The model is able to estimate the required power with an average accuracy of over 6% for a random subset of the noon report data. Due to challenges inherent to noon reports as a data source, the actual effect of trim and speed have a bigger magnitude than the extracted trend. Ship Design, Production and Operation
An Independent, Generic, User-Commanded, Sequential Quadratic Programming Module for Solving the Aircraft Trim Problem
No full textThe Delft University of Technology (’TU Delft’) developed a real-time distributed system for scientific and educational purposes. Because of the high level of expertise required to learn from- and work in a real-time environment, TU Delft created a middleware layer, DUECA (Delft University Environment for Communication and Activation), and a simulation-specific addition framework: DUSIME (Delft University SIMulation Environment). A common practice is embedding the numerical optimization tool in an aircraft model and retrieving the starting conditions, referred to as the initial trim set. Setting up such an embedded tool for every aircraft model is very labor-intensive. For over 20 years, these issues have limited the overall user experience in DUECA. Hence, the research created an independent, generic, User-commanded, Sequential Quadratic Program (SQP) module capable of solving the aircraft trim problem in DUECA. The trim module works by a user selecting a desired steady-state aircraft trajectory through a Graphic User Interface (GUI) and then commands the trim module to search for the set of initial trim conditions. The advised flight trajectory found so far by minimizing the DASMAT trim problem are the straight-and-level descending, pull-up, and turning flight. The calculated initial trim sets allow the starting up of an aircraft simulation in a steady-state, stable enough such that a pilot can take over manual control.Aerospace Engineerin
Trim optimization for ships in service: A grey-box model approach using operational voyage data
No full textTrim optimization is an approach considered by the industry to improve the energy efficiency of ships, having a potential in both reducing operational costs and to decrease the emissions of the ship. Potential fuel consumption reduction by trim optimization is 0.5 to 3 % and to up to 7% in extreme cases. Stolt Tankers, a shipping company active in the chemical tanker market, wants to increase the energy efficiency of their ships in operation by trim optimization. For a limited number of ships, trim tables from model scale towing tests are available, but these are not used and the accuracy of these tables are unknown. The objective of this research was to develop a method to decrease fuel consumption by trim optimization, by a dynamic fuel consumption estimation model based on available operational data, that can be integrated in the voyage management system of Stolt Tankers. A dynamic fuel consumption estimation model has been developed, using mainly the noon report data of the C-38 ship class, consisting of six sister vessels of 38 000 DWT chemical tankers. Quality of noon report data is an issue: human error in observing and recording data causes noise and a mismatch exists between the snapshot of conditions on one hand, and the 24 hr averaged sailing speed and recorded shaft power or fuel consumption on the other hand. A data pre-processing framework has been developed and applied to integrate and transform the data, clean and filter the data. The model is able to extract the effects of speed through water, mean draft, trim, sea water temperature, wind force, sea state and swell state and their relative direction to the ship and days since last hull cleaning and propeller polishing. The model has shown to perform optimal using the regression model of Lutzen and Kristensen (2013), combined with a multiple layer feed-forward neural network, consisting of 1 hidden layer with 15 neurons. The model is able to estimate the shaft power with an average accuracy of 6.58 % for a random test set of the noon report data. It is able to extract the effect of trim on shaft power and to consider the effect of weather and fouling conditions. Model results show that about 1 to 2% of shaft power per 0.50 m can be saved, with trim by bow being the optimal trim. Based on sea trial results, it is concluded that the model performs most accurate for conditions that are represented by a high quantity of historical data. The model can be applied for speeds between 12 and 14 knots and for mean draft conditions of 9.5 m and more. Within this range, the effect of trim and weather conditions are followed with reasonable accuracy. It is confirmed by the sea trial that trim by bow is the optimal trim, with a much stronger magnitude of the effect of trim on shaft power. A difference of 6 to 8% in shaft power was found for a change in trim of 0.50 m.Marine Technology | Ship Design, Production and Operation
A trim problem formulation for maximum control authority using the Attainable Moment Set geometry
No full textThis paper presents a generic trim problem formulation, in the form of a constrained optimization problem, which employs forces and moments due to the aircraft control surfaces as decision variables. The geometry of the Attainable Moment Set (AMS), i.e. the set of all control forces and moments attainable by the control surfaces, is used to define linear equality and inequality constraints for the control forces decision variables. Trim control forces and moments are mapped to control surface deflections at every solver iteration through a linear programming formulation of the direct Control Allocation algorithm. The methodology is applied to an innovative box-wing aircraft configuration with redundant control surfaces, which can partially decouple lift and pitch control, and allow direct lift control. Novel trim applications are presented to maximize control authority about the lift and pitch axes, and a “balanced” control authority. The latter can be intended as equivalent to the classic concept of minimum control effort. Control authority is defined on the basis of control forces and moments, and interpreted geometrically as a distance within the AMS. Results show that the method is able to capitalize on the angle of attack or the throttle setting to obtain the control surfaces deflections which maximize control authority in the assigned direction. More conventional trim applications for minimum total drag and for assigned angle of elevation are also explored.Flight Performance and Propulsio
TRIM : – Method for identifying risks and estimating project time
No full textITT Flygt is a world leading company that mainly manufactures submersible pumps. A problem of ITT Flygt is that product development projects rarely manage to hold the estimated project time. It shows that something unexpected occurs in projects quite often, which results in delays. The delays can both be due to an optimistic time plan of projects and risks in product development projects which are not discovered at an early stage. This added with unforeseen delays makes it difficult for ITT Flygt to estimate the duration of their projects. The goal with the Master thesis is to examine a suitable method for simulation of project time. By doing probability calculation for a project schedule a risk analysis can be done. Another aim of the thesis is to create a method that enables the identification of risks in product development projects. To examine this, both an extensive literature study and empirical study was performed. The empirical studies include interviews with project managers at ITT Flygt and studies of other companies. MatLab were used to examine possible simulation methods to estimate the duration of a project. On the basis of ITT Flygt´s problem and prerequisites a method was made with the name The Risk Identification Method (TRIM). TRIM is a method which is described in a practical and standardized way of working, where a project’s different areas are analyzed to identify risks. The method contains a checklist where constantly recurring risks in product development projects can be found, and a way to identify unique risks through a project specification. Another part of TRIM is to do a project time simulation. The best suitable simulation method for ITT Flygt is the Monte Carlo simulation. By doing a simulation graphs over estimated project time can be accomplished as well as the critical path can be studied. To the simulations ITT Flygt is required to use the cost and schedule risk analysis program @Risk for Project. TRIM gives ITT Flygt the opportunity to work in a structured way when it comes to risk analysis of projects. The authors demand, as far as they are concerned, is that those who use the method should continuously do updates of the checklist and the input data which are used in the Monte Carlo simulation.Examensarbetets syfte är att få fram en lämplig metod för att simulera projekttider. Genom att ta fram sannolikhetskurvor för ett projekt kan en tidplans risknivå utvärderas. Ett annat syfte är att hitta en arbetsmetod för att fånga upp risker i produktutvecklingsprojekt. För att undersöka detta gjordes både en omfattande litteraturstudie och en empirisk studie som dels bestod av företagsbesök och dels av intervjuer av projektledare på ITT Flygt. För att undersöka lämplig simuleringsmetod av projekttid gjordes tester i Matlab. Utifrån ITT Flygts problem och förutsättningar togs ett förslag på metod fram vid namn Total Risk Identification Method (TRIM). TRIM är en metod som på ett praktiskt sätt beskriver ett standardiserat arbetssätt där ett projekts olika områden analyseras för att hitta tänkbara risker. Till stöd för riskidentifikationen används en checklista över återkommande risker och kravspecifikationen används för att hitta för projektet unika risker. Som en del av TRIM ingår även att en projekttidssimulering ska göras. Den typ av metod som anses mest lämpad för ITT Flygt är en Monte Carlo-simulering. Genom att göra en projekttidssimulering kan både en kurva över projektets sannolika tider tas fram likväl som den kritiska linjen kan studeras. Den kritiska linjen är den kedja av aktiviteter som bestämmer den totala projekttidens längd. För att göra Monte Carlo-simulationer rekommenderas ITT Flygt att använda ett program som heter @ Risk for Project. TRIM är en möjlighet för ITT Flygt att få ett mer strukturerat arbetssätt vid riskanalyser av projekt. Författarna anser dock att det kommer att ställas krav på att de som använder metoden dels håller checklistan uppdaterad och dels uppdaterar den indata som krävs för Monte Carlo-simuleringen
Ballast trim system for a modern SSK submarine: A research project on ballast trim systems for a modern SSK submarine based on the BB2 submarine hull by comparing and modelling different solutions
No full textKeeping a submarine stable underwater is important to be able to execute missions. Therefore, one of the main systems on board of submarines is therefore the ballast trim system. This system is able to maintain the submarine balanced. There must be equilibrium in weight and buoyancy as well as in the trimming moment. This makes the ballast trim system a vital system on board of submarines.The world around us changes, causing new mission specifications and requirements. This results in a different operational profile than before, which has consequences for the ballast trim system. For example, for a modern submarine hovering is desired, resulting in a faster and more accurate ballast trim system. Therefore, the existing systems must be reconsidered for modern SSK submarine applications. Next to the changed environment, new technologies are available, which might be applicable for a modern SSK submarine. The main goals of this research are: give insight in the ballast trim system and see which technologies are best to use in the ballast trim system. The technologies are tested on the 4000 and 2000 ton BB2 submarine.In this research different empirical models were set up in order to simulate the behaviour of the different ballast trim systems. The results of these models are compared to each other based on energy, noise and redundancy. As an input, different mission profiles were made, which are likely to be executed by a modern SSK submarine. The ballast trim system was divided into three separate systems for the comparison, namely: trim, compensation and hover. From the simulation made there was seen which modelled solutions were the best capable to use as a ballast trim system. In this research also the second order effects of waves were included. There is seen from the simulation that it is possible to compensate for the motions due to these second order wave effects. The simulations also showed that a new technique, the so called ‘variable buoyancy system’ is very promising.With the results from this research it can be seen which system can be best used as ballast trim system for the three different tasks on board of the BB2 submarine. To maintain longitudinal equilibrium, it is best to use a centrifugal pump to transfer ballast water between tanks. To maintain balance between the weight and buoyancy forces of the submarine, it is best to use a plunger pump. It is also seen that a centrifugal pump in a system with a very large static head compared to dynamic head, is hard to operate and can even become incapable of expelling water from the tank. For hovering, a special dedicated system is needed. For the 4000 ton BB2 submarine, it is best to use a pre-pressurised tank to lose weight very fast in case of a change in seawater density. The 2000 ton BB2 submarine can use its snorkel mast to maintain equilibrium. For low frequency forces such as the second order forces due to waves, both studied BB2 submarines can use their snorkel mast to keep the submarine at depth. Marine Technology | Marine Engineerin
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