90 research outputs found
"Simha Rotem (1924-2018): Ad memoriam. The broom and the resilience"
No full textSimha Rotem was born in Warsaw in 1924. He was one of the most important member of the Warsaw
Ghetto uprising in April 1943. Under the cover name of Kazik. He was a leader of the young Jews who were one of the
first in Europe to rebel against the Nazi occupation. His original name is Symon Rathajzer, who upon his arrival in
Israel he changed in Simha Rotem to symbolize a new beginning. His heroic and history is full of anecdotes that
encroach of the unbelievable. Rotem came in and out of the ghetto, through the city’s sewers, besieged and burned, to
bringing news and organizing the escape of the few survivors. Thanks to him the last fighters of the ghetto succeeded in
acriding the “Aryan” area of the city, finding refuge from not Jewish people connected with the Polish resistance. In
1944 Rotem fighted in the Warsaw uprising against the Nazi occupation. He was one of the leader of the Jewish exodus
from Poland to Israel. He contributed to save thousands of people. The author died in Jerusalem in 2018
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Yemeni Jewish identity in the works of Simha Zaramati Asta
No full texttextIn this paper, I consider the collection of short stories and photographs Neighborhood Album A by Yemeni Israeli author Simha Zaramati Asta. I argue that Asta contributes to a distinctively Yemeni Jewish literature and identity in Israel. While Asta could be considered a Mizrahi author, I claim that a study of Asta’s text as Mizrahi in fact erases the distinctive Yemeni elements of Asta’s writing. Instead, Asta is purposeful about her inclusion of Yemeni culture and her establishment of Yemeni identity in her text. This Yemeni culture is evident in Asta’s inclusion of the songs of Yemeni Jewish women which constitute an oral tradition of memory within Yemen and Israel. Asta further creates a distinctive Yemeni identity through a sense of place in the Yemeni Quarter of Tel Aviv in both her stories and photographs. Through descriptions of the sights, smells, and traditions of the Yemeni Quarter of Tel Aviv, Asta elevates the neighborhood, claiming it as a place where the divine spirit can be found. While Asta is purposeful in her creation of a distinctively Yemeni Jewish literature and identity, she demonstrates the hybridization of this Yemeni Jewish literature and identity with Israeli literature and identity. By noting the importance of Yemeni Jews to the creation of Israel and the influence of Israel on these Yemeni Jews, Asta claims Israeli identity for Yemeni Jews. She demonstrates the hybridization of the Yemeni Jewish identity and Israeli identity through intertextual references to canonical Israeli poets and authors. Yet while Asta values this hybridization, she uses the characters in her stories to question whether the hybridization of Yemeni Jews in Israel can in fact succeed.Middle Eastern Studie
Computational Modeling and Analysis of Heavy Fuel Feasibility in Direct Injection Spark Ignition Engine
No full textDirect Injection spark ignition (DISI) technology is helpful for the present day engine to increase the fuel efficiency. Power output and the choice of fuel as the demand and scarcity for fossil fuels are increasing. As a new technology DISI engines are employed in some commercial cars like the Pontiac Solstice using gasoline fuel. The advantages of DISI engines like use of different fuels, reduced compression ratio, reduced injection pressure and reduced operating pressures in DISI engines has not been widely tested. As a new technology DISI engines lack experimental results and combustion co-relations that can be directly used as in the case of conventional engines. The experimental analysis of this technique is very expensive as it involves large number of parameters to be changed each and every time the experiment is done. This makes the experimental analysis of DISI engine a costly and time consuming task. Computational fluid dynamics on the other hand can simulate the combustion process and let researches visualize the process of combustion inside the cylinder.
The ability of DISI engine to work on different fuels in the engine is successfully tested. Two engines, reciprocating and rotary, equipped with DISI technology is simulated in FLUENT. The engines are selected in such a way that they represent the major part of engine family to show that DISI technology is feasible in any type of IC engines. Because of unavailable experimental data on DISI diesel engines, the models used in the thesis are validated with a gasoline DISI reciprocating engine. The validated model is used for parametric study of diesel fuel in DISI engine. It was found that the engine parameters need to be tuned to avoid the undesired effects of diesel fuel. After several parametric changes, combustion and power output which is identical to the experimental validated case are obtained. Hence it has been proved that the diesel fuel can be successfully utilized in DISI engine. This technology is then applied to the rotary engine. Because of the change in geometry and many other specifications, the parameters used for reciprocating engine are not feasible for rotary engine. Therefore a parametric study on rotary engine is carried out to obtain a good combustion and power output.
It is proven successfully in this thesis that DISI technology can be applied to any engine and can use any kind of fuel. However, each and every engine needs to be tuned according to its specifications and geometrical constrains to obtain the maximum fuel to air mixture and therefore the maximum power output. The thesis explains the influence of parameters on the power output considering the important properties of fuel such as cold start ability, flash point detonation, volatility and density. The behavior of fuel and flow physics inside the cylinder is visually explained. The fuel air interaction, which is very important to have a good air fuel mixture formation, is extensively studied and the methods are developed to time the injector depending on the air turbulence inside the cylinder. The conclusions in this thesis demand the importance of further studies of this technology. The results of the thesis show that this technology can be used as a more energy efficient and echo friendly technology. However, further studies on this technology are essential to build a flawless more efficient technology in the field of IC engines
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Probing the Cosmic Web with Fast Radio Bursts
No full textFast Radio Bursts (FRBs) are enigmatic, millisecond-duration extragalactic transients discovered only in the late 2000s. Though the exact nature of their origin is unknown, their extremely short-duration emission endows several unique qualities that make them uniquely useful as probes of foreground matter. Chief among such properties is their dispersion. As FRB light propagates through plasma, their radio frequencies are dispersed, resulting in higher frequencies arriving before lower frequencies at Earth. The dispersion is directly proportional to the line-of-sight integral of the electron density weighted by the cosmological scale factor, i.e., the Dispersion Measure (DM). The DM of each FRB can be measured extremely precisely (~1%) by radio telescopes during detection. Thus, FRB DMs precisely probe foreground ionized matter, especially the warm, hot intergalactic medium (WHIM), a previously difficult-to-detect phase of matter. In this manuscript, I first describe the detection of the so-called "missing" baryons, a long-standing cosmological conundrum with FRBs. Then, I present work I have led that establishes the technique of foreground mapping, i.e., leveraging optical observations of foreground galaxies to constrain DM contributions from intervening foreground structures such as halos and cosmic-web filaments. Finally, I present the results of the FLIMFLAM survey, a statistical treatment of the foreground observation of several FRB sightlines to produce novel constraints on gas fractions within halos and filaments. I conclude with prospects for a FLIMFLAM-like analysis with a significantly larger sample of FRB sightlines expected to be detected within the next three years
Switched Control Strategy for Robust Formation Flight with HIL and In-Flight Validation
No full textIn recent times, Unmanned Aerial Vehicles (UAVs) have been intensively studied for a wide range of military and civil applications such as surveillance and reconnaissance missions, agriculture, traffic monitoring, pollution control, meteorological data collection, pipeline survey, early fire detection, rescue missions, wildlife population monitoring, etc. The above tasks can be carried out faster and more efficiently by a group of UAVs flying in formation. This paper presents the application of two stage switching controller in autonomous formation flight of UAVs based on the leader follower configuration. The constructed UAV airframe, as well as the autopilot, formation flight control unit and wireless communication link for data sharing between UAVs were presented and described. The advantages of the switched control were demonstrated in terms of a significantly larger region of stability in maintaining formation, as opposed to the standard, one stage control laws with classical compensators. Hardware In The Loop (HIL) tests of proposed formation flight control were performed, during which the inertial states and flight parameters were logged. The HIL test rig enabled us to verify the formation flight control performance which was further substantiated by actual flight tests.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.Embedded System
Evaluating different localization methods for robotic swarming
No full textLocalization is an important element for a moving swarm of robots. A swarm contains many individuals, and it is essential that the swarm members do not collide. Expensive and complex implementations to localize others is undesirable. Hence, a localization system designed using the available resources is desired. The available techniques that have been analysed are Received Signal Strength Indicator (RSSI), Time difference of arrival (TDOA) using the ESP-NOW protocol and a spinning time of flight (TOF) sensor. The spinning TOF sensor showed to be the most promising, with close range distance detection only containing a maximum errors of 5cm. The sensor is implemented as a cheap LiDAR system by mounting it to the front of the robot, which spins around its own axis. An IMU is responsible for keeping track of the orientation of the TOF sensor. Furthermore, two small algorithms were designed and compared in order to process the TOF data.Electrical Engineerin
Two dimensional swarming: Neighbour detection
No full textRobot swarming has been done for quite some years now. However, creating a very large swarm can become very difficult, since the networking becomes complex. With small swarms, a robot can broadcast information, or a central node can coordinate the robots. However, when a swarm becomes very large, these techniques fall short. Broadcasting all information is too much to be evaluated by every single robot, and a central node can't control it as well.In this research, we have looked at how nature works and tried to find a solution by mimicking its behaviour. In nature, animals stay in a swarm, based on their instinct combined with following their neighbours' behaviour.This document is part of a bigger research which implements a bird-flocking algorithm with cars. For bird-flocking, the speed and heading of neighbours need to be known. Detection of neighbours with robots is technically challenging.We have researched a way to detect neighbours based on a hardware filter based on RSSI, in combination with a software filter.Electrical Engineerin
Extended Observer Forms for Submersive Discrete-time Systems
No full text—This technical note addresses the problem of transforming a single-input–single-output discrete-time system into the extended observer form, which comprise a linear time-invariant observable component, and a nonlinear injection term, which depends on the input, output, and their forward shifts up to a finite order. Intrinsic necessary and sufficient conditions are provided for obtaining the extended observer form via a parametrized state transformation. The conditions are formulated directly in terms of the state equations and do not rely on input–output equations as in the earlier papers. Further, an algorithm for obtaining the required transformation is presented. Unlike the existing results on observer forms, the results are not restricted to reversible systems but to more general submersive systems, i.e., to systems, which are reversible via static state feedback.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.Networked System
Swarming: A Control Algorithm for Swarming Autonomous Robots
No full textA swarm at its most basic description consists of multiple individuals all performing actions based on their immediate surroundings. The challenge for robotics is creating a control algorithm that processes these surroundings and takes appropriate actions as a consequence. The focus of this document is the bird flocking algorithm. For this reason, the main focus points for the control algorithm will be heading alignment, neighbor distance maintenance \& collision avoidance.Electrical Engineerin
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